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  • American Institute of Physics (AIP)  (46,193)
  • Annual Reviews  (5,896)
  • Munksgaard International Publishers  (320)
  • 1990-1994  (49,008)
  • 1970-1974  (1,509)
  • 1965-1969  (1,170)
  • 1955-1959  (722)
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  • 1
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: This investigation was performed to assess the bone-to-implant surface contact at fixtures of titanium that either had a standard machine prepared or a TiO2-blasted surface. Five beagle dogs were used in the experiment. Extractions of the premolars were performed in the maxilla. After 4 months of healing, 5 standard machine-prepared fixtures and 5 prepared according to the TioBlast technique were inserted. Two months later another 5 “standard” and 5 TiO Blast-prepared implants were inserted. Four months after the first fixture installation, the animals were killed and ground sections prepared from each implant site. Of the 20 implants installed, 19 were successfully incorporated. The mean bone-to-implant surface for “standard” fixtures was about 40% both at the 2 and 4 months observation interval. The corresponding figures for the TiO Blast-prepared fixtures were similar during the first 2 months of observation, while subsequently the TioBlast-prepared fixture surface seemed to stimulate to a more close bone-to-implant contact (65%) than the “standard” one.
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  • 2
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A photogrammetric technique was tested to measure the topography of the mucosa around implants, placed in edentulous upper jaws. Photographs were taken of casts from 6 patients, who all had used a removable overdenture for one year. Another series of photographs was taken on new casts after the use of a fixed prosthesis for a second year. The 6 pairs of photographs were measured and compared in an analytical stereo plotter for surface contour and implant positions. The results from the measurements indicated a trend of general recession of the mucosa after one year with fixed prosthesis. both on the buccal as well as on the palatal side. The mean volume of recession was 222.4 mm3, corresponding to an average of 0.4 mm3/mm2 of mucosa. More recession was generally observed on the palatal side, but obvious variations between the patients were present. In conclusion, the photogrammetric technique was considered to be well suited for analysing tissue contours in various dental situations.
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  • 3
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The aim of this study was to explore the possibility of creating bone tuberosities on the mandibular ramus in rats, using a rigid, occlusive. Teflon capsule. The experiment was carried out in 30 rats. The mandibular ramus was exposed bilaterally. On the test side, the periosteum was left covering the lateral surface of the ramus. On the contralateral side (control). the periosteum was elevated from the lateral surface together with the flap. A hemispherical, Teflon capsule was then placed to face the periosteum or the bone surface with its open part before closure of the wound. The healing periods comprised 7–120 days. Histological analysis demonstrated increasing bone fill in the test specimens from 7 to 60 days, and a limited further increase was observed from 60 to 120 days. In the control specimens, limited bone fill was seen within the first month after surgery, but substantial amounts of new bone were produced from 30–120 days. At 120 days, the mean amount of bone obtained in the test specimens was 56%(range 39%-71%) of the total space created by the capsules, and it was 52%(range 32%-85%) in the controls. The amount of newly formed bone was equivalent to a 5–6 times increase of the original width of the mandibular ramus. These findings indicate that a secluded space created by an occlusive barrier adjacent to existing bone or periosteum may be filled out with bone tissue. This may have a great clinical impact in cranial and maxillofacial surgery.
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  • 4
    Electronic Resource
    Electronic Resource
    Copenhagen : Munksgaard International Publishers
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Seventy-six patients were consecutively treated with fixed prostheses supported by osseointegrated implants in the edentulous maxilla and followed up for 5 years. The mean bone quality and resorption indices were 3.1 and 2.7 at the time of implant placement, respectively. Altogether, 449 standard Brånemark implants were placed. Two patients resumed to complete dentures, and the cumulative implant and prosthesis survival rates were 92.1% and 95.9% for 5 years, respectively. The mean marginal bone level was 0.6 mm below the reference point at the time of placement and 1.2 mm below the same point 5 years later. Speech problems was the most frequent complaint during the first year of function, while resin fractures caused most adjustments during the follow-up period. No implant, abutment or gold alloy screws were found to be fractured, and only 4 patients had their prostheses re-tightened due to loose gold alloy screws.
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  • 5
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: There is increasing interest in how pathways of tissue destruction around dental implants are similar as for teeth and how these pathways can be modulated to slow loss of supporting bone. The purposes of this study were to develop a short-term animal model to study the effect of the nonsteroidal anti-inflammatory drug flurbiprofen, on slowing the rate of induced peri-implant bone resorption. A total of 20 cylindrical titanium implants were placed in 2 beagle dogs using a low-trauma surgical technique. During the 3-month healing period without functional loading of the implants, daily oral hygiene was performed to maintain a Gingival Index of 0 to 0.5. At completion of the healing period, a baseline evaluation was performed which included the uptake of the bone-seeking radiopharmaceutical (BSRU)99mtechnetium-tin-diphosphonate (99mTc-Sn-MDP) in peri-implant bone and standardized radiographs. Peri-implantitis was induced with 4-O silk ligatures, cessation of oral hygiene and soft diet. One beagle was given 0.02 mgikg of flurbiprofen by mouth; the other received a placebo. BSRU and radiographic height of bone were remeasured to calculate the rate of bone loss during the 60-day treatment period. The percent rate of bone loss during the study period was calculated from the radiographs using a computer-assisted method. The radiopharmaceutical uptake for the flurbiprofen-treated implants remained unchanged. However, BSRU for placebo-treated implants was significantly increased from baseline. Radiographic measurements of bone height revealed that the mean rate of bone loss around implants in the flurbiprofen-treated dog (0.066±0.351%/month) was significantly lower than the rate around implants in the placebo-treated dogs (5.729±0.384%/month) over the 60-day treatment period. These data indicate that peri-implant bone loss can be rapidly induced and measured in the beagle and that flurbiprofen. administered orally, can significantly decrease the rate of induced peri-implant bone loss.
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  • 6
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: This report presents 4 cases with 6 implant exposures after the installation of Bråemark System® implants which called for treatment applying the guided bone regeneration technique. A bioresorbable barrier (GUIDOR® Matrix Barrier) was used to cover the defects, 4 defects with and 2 without the support of autologous bone chips. Complete bone filling was found in 4 (2 without and 2 with bone chips) and partial filling in 2 (with bone chips) of the treated defects, as registered at the abutment connection 6–7 months after surgery. Besides its ability to serve as a barrier for guided bone regeneration, it was found that the matrix barrier had the following properties; biocompatibility observed as uneventful tissue healing, malleability facilitating the clinical handling and ability to be resorbed within 6 to 7 months, as evaluated by clinical inspection. The observations of the present case reports indicate that the tested barrier may be used for guided bone regeneration in connection with implant installation. It is advisable, however, to use a supporting material to prevent barrier collapse, although bone regeneration can be achieved in certain situations without such material if the defect morphology is favourable.
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  • 7
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: This study details the structural and ultrastructural features of the interfaces between titanium implants and their surrounding tissues. The material stemmed from an experiment in dogs in which guided tissue regeneration with Gore-Text membranes was used to treat peri-implant, ligature-induced tissue breakdown around submerged and nonsubmerged com-mercially pure titanium implants. Specimens from the nonsubmerged group were evaluated under light microscopy and scanning and transmission electron microscopy. A healthy gingiva and a gingival sulcus were formed around the implant necks. A regenerated junctional epithelium provided the epithelial union between implant and gingiva. The supracrestal connective tissue was characterized by a 3-dimensional network of collagen fibers, fibroblasts and blood vessels. Near the implant surface the collagen fibers ran parallel to the titanium surface or were orientated perpendicular to the implant. The connective tissue-implant interface was characterized by a fine fibrillar material interposed between the implant surface and the connective tissue. An unidentified material was also observed between the endings of functionally orientated collagen fibrils and the metallic surface. The apical portions of the implants were anchored in compact bone. At the bone-implant interface, either mineralized bone matrix was intimately adapted to the titanium surface without any intervening space or a 0.5 μm wide unmineralized layer was interposed. These findings indicate that a perimucosal seal was formed around the implants consisting of a junctional epithelium-implant union coronally and supported by the connective tissue-implant junction apically. The implants were integrated in connective tissue, but only tightly adapted to bone.
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  • 8
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The principle of guided tissue regeneration has been successfully applied for the regeneration of bone in various jaw defects in human. The purpose of this study was to assess the bone volume regenerated using nonresorbable membrane barriers. Nineteen patients with jaw bone defects of various sizes and configurations were included in the study. Combined split-thickness/full-thickness mucosal flaps were elevated in the area of missing bone. The size of the defects was assessed by measuring the distance from a reference line between 2 adjacent teeth (cementoenamel junctions) to the alveolar crest (a) every 2 or 3 mm. In addition, the crestal width was measured. Consequently, the surface of the triangle formed by a and the width of the crest as well as the volume between all triangles were calculated geometrically. Following the placement of Gore-Tex® augmentation material as a barrier, the distance (b) to the top of the membrane from the reference line was assessed, and the maximum possible volume for bone regeneration based on (a-b) and the width of the crest was calculated. At the time of membrane removal (3–8 months later). the same measurements were performed and the percentages of regenerated bone in relation to the possible volume for regeneration determined. In 6 patients in whom the membranes had to be removed early due to an increased risk for infection between 3 and 5 months, bone regeneration varied between 0 and 60%. In 13 patients in whom membranes were left for 6–8 months, regenerated bone filled 90–100% of the possible volume. It was concluded that successful bone regeneration consistently occurred with an undisturbed healing period of at least 6 months.
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  • 9
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A photogrammetric technique was designed to measure the position of dental implants in 3 dimensions to enable assessment of the tit of superstructures placed on the implants. A relatively simple camera setup was developed and tested. Calibration of the camera was performed in a high-precision analytical plotter and revealed a film measurement accuracy of 0.005 mm. The achieved measuring accuracy for clear and well defined points on clinical components was found to be around 0.02 mm. To find the center points of the implants, points on the circumference were measured. These points are not well defined, which resulted in an estimation of the center point of the implant with a precision of 0.05 mm. Independent measurements of a prosthesis with 5 implants were also within the precision of 0.05 mm. The angular orientation of the top surface of the implant cylinder (abutment, brass replica of gold alloy cylinder of the framework) was measured with a precision of 0.01 radians, which corresponded to an error with a peripheral gap of about 0.03 mm. This value was about 5-10 times lower than the clinical fit between frameworks and abutments, measured in 3 randomly selected clinical cases.
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  • 10
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Background. In the Danish Town Hall Study" it has previously been shown that the sick building syndrome is a widespread phenomenon. This has given rise to speculations as to whether biologically active components in dust or whether absorbed organic gases and vapours in the indoor climate may be partly responsible for the sick building syndrome. Therefore, we wished to study whether qualitative conditions in dust, of a physical, chemical, and biological nature, are related to the prevalence of symptoms of the sick building syndrome. Material and methods. The study included 12 town halls in the Copenhagen area. A total of 870 persons participated, 584 women and 286 men. All the participants filled out a questionnaire regarding health and working conditions, and dust samples were collected with a special vacuum cleaner in the working environment of the participants, after which the contents of inorganic and organic particles as well as of human source fragments the (hair, nails, skin) and various fibres were determined. Results. There was a significant correlation (P〈0.05) between the prevalence of gram-negative bacteria in the indoor climate dust, and general symptoms (fatigue, heavy-headedness, headache, dizziness, concentration problems) (corr.coeff.=0.73), as well as symptoms from the mucous membranes of the upper respiratory tract (corr.coeff.=0.76). Also, there was a significant relation between the prevalence of particles in the dust and the prevalence of symptoms from the mucous membranes (corr.coeff.=0.81). There was a strong and significant correlation between the total amount of volatile organic components (TVOC) and lack of concentration (corr.coeff. =0.85) and feeling heavy-headed (corr.coeff.=0.72). Macromolecular dust (potentially allergenetic material) was significantly correlated to the prevalence of headache and general malaise/dizziness (corr.coeff.=0.66), while the ability of the dust to liberate histamine was significantly related to the prevalence of general malaise, dizziness (corr.coeff.=0.65) and lack of concentration (corr.coeff. =0.58). Further analyses including a number of potential confounders did not change the results of the above analyses. Conclusion. The results of this study support the hypothesis that qualitative properties of dust are important to the sick building syndrome. The study was based on relatively few buildings, but nevertheless strong correlations were found. In perspective, epidemiological intervention studies should be carried out to investigate whether minimizing the amount of both dust and bacteria in the indoor climate affect the prevalence of sick building syndrome.
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  • 11
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 4 (1994), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
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  • 12
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 4 (1994), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
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  • 13
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 4 (1994), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: We tested nasal detection thresholds for airborne chemicals in a group of anosmics (i.e., subjects lacking a functional sense of smell) and in a group of age-, gender-, and smoking-status-matched normosmics (i.e., subjects with normal olfaction). Anosmics provided odor unbiased nasal pungency (irritation) thresholds. Normosmics provided odor thresholds. Homologous series of alcohols, acetates, and ketones served as stimuli. Eye irritation thresholds were also measured for selected acetates. Most substances evoked pungency (i.e., were detected by the anosmics). All sensory thresholds decreased systematically with carbon chain length. The gap between pungency and odor grew larger with increasing carbon chain length. Pungency thresholds-but not odor thresholds-showed a uniform linear relationship of slope close to unity with saturated vapor concentration, irrespective of chemical functionality or carbon chain length. This suggests that pungency from nonreactive airborne chemicals rests heavily on a relatively unspecific physical interaction with a susceptible biophase. Of relevance to indoor environments, such an interaction opens the possibility for a high degree of sensory addition of pungency from individual components of complex mixtures resulting in noticeable irritation even when each component is at a level well below threshold value.
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  • 14
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 4 (1994), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: The filtration efficiency of ventilation air cleaners is highly particle-size dependent over the 0.01 to 3 μm diameter size range. Current standardized test methods, which determine only overall efficiencies for ambient aerosol or other test aerosols, provide data of limited utility. Because particles in this range are respirable and can remain airborne for prolonged time periods, measurement of air cleaner fractional efficiency is required for application to indoor air quality issues. The objectives of this work have been to 1) develop a test apparatus and procedure to quantify the fractional filtration efficiency of air cleaners over the 0.01 to 3 μm diameter size range and 2) quantify the fractional efficiency of several induct air cleaners typical of those used in residential and office ventilation systems.Results show that efficiency is highly dependent on particle size, flow rate, and dust load present on the air cleaner. A minimum in efficiency was often observed in the 0.1 to 0.5 μm diameter size range. The presence of a dust load frequently increased an air cleaner's efficiency; however, some air cleaners showed little change or a decrease in efficiency with dust loading. The common furnace filter had fractional efficiency values of less than 10% over much of the measurement size range.
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  • 15
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 4 (1994), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: The indoor concentrations of contaminants originating from outdoor sources have been measured and calculated under transient conditions. The results show that contaminants that are supplied to an office building via the ventilation system can reach considerably high concentration levels. The indoor/outdoor concentration ratio and time lag are dependent on the air change rate. In buildings with low air change rates the indoor concentration variations are smoothed out compared to buildings with high air change rates. The results from the theoretical model are compared to the results from both laboratory and field measurements and the model is verified for well mixed conditions in a 20 m3 test chamber. The model can be used to simulate different control strategies for reduction of indoor contaminant concentrations related to outdoor sources. One such control strategy is based on reduction of the outdoor air change rate during periods with peak outdoor contaminant concentrations.
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  • 16
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: To test the reproducibility of a questionnaire previously used to study the association between respiratory symptoms and home dampness/mold, it was sent to the parents of 1,596 children twice, with an interval of one month between distributions. A total of 770 respondents completed the questionnaire both times and were entered into an analysis. For exposure variables, percentages of agreement between the two administrations ranged from 87% for visible mold growth in the home to 95% for basement flooding. Respective kappa scores ranged from 73% to 82%. Percentage agreements for the adults' symptoms variables ranged from 80% for upper respiratory symptoms, to 99% for physician-diagnosed asthma. Percentage agreements for children's symptoms ranged from 81% for upper respiratory symptoms to 97% for current asthma. For all symptoms kappas ranged from 59% to 90% indicating moderate to high reproducibility. Future research should now concentrate on validating the questionnaire as an indicator of mold growth.
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  • 17
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: There are few data sets appropriate for characterizing the indoor concentrations of air pollutants over the long term. An understanding of the variability in indoor pollutant levels is particulurly relevant to the design of epidemiologic investigations: misclassifiation of exposure due to the inaccuracy of exposure estimates tends to weaken the association of exposure with health outcome. This paper uses a series of indoor NO2 measurements collected at two-week intervals over 18-month periods between 1988 and 1991 to describe the seasonal and year-to-year variability in indoor NO2,. The data show that there can be large year-to-year differences in both the sample distribution of indoor NO2 as well as the household average. For homes with gas ranges with continuously-burning pilot lights, the average bedroom NO2 concentration was 25% higher in the winter of 1990-1991 than in the winter of 1989-1990 but only 4% higher during the winter of 1988-1989 than during the winter of 1989-1990. The winter-to-winter correlations within homes ranged from a low of 0.53 to a high of 0.88. The year-to-year differences in mean indoor concentrations were not related to temperature patterns. Occupant behaviors that influence air exchange rate and/or source use are hypothesized to be the major determinant of the observed pattern. Exposure data collected during a single year should be cautiously extrapolated to other years. However, in Albuquerque homes, the data suggest that the year-to-year variability in household NO2 levels will not have a strong impact on classifying exposure into broad categories.
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  • 18
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 4 (1994), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
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  • 19
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Microbial content in dusts such as bacteria, endotoxins and fungal spores are thought to be important causative agents for the symptoms in organic dust-related diseases. Micro-organism-induced mediator release was therefore examined in human cells. Bacteria were found to trigger the release of histamine and leurotriene B4 from bronchoalveolar cells, and in suspensions of dispersed lung and tonsillar cells they induce the release of histamine and prostaglandin D2. Basophil histamine release was triggered by both bacteria and their endotxins. Furthermore, histamine release caused by allergic as well as non-allergic reactions was enhanced by bacteria, endotoxins and fungal spores of mould. These effects of dust components may be crucial for the symptoms in q a n i c dust-related diseases, since the mediators are of key importance to the broncho-obstructive and inflammatory events in these disorders.
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  • 20
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: The development of standardized non-culture-based approaches capable of assessing microbial contarnination of airborne dust is sorely needed. Direct chemical analysis has previously been successfully used for measuring components unique to Gram-negative bacteria. In the present study, dust from primary filters of hospital air-conditioning intake systems (which filter incoming outdoor and recirculated air) and dust from secondary room filters (filtering primarily indoor air) were analyzed. Dust from home air-condition-ing filters (which also filter outdoor air, with recirculation) were also analyzed. Muramic acid is an aminosugar present in Gram-positive and Gram-negative bacterial cell walls and can serve as a measure of bacterial contamination in dust. Samples were analyzed by gas chromatography-mass spectrometry after hydrolysis and conversion of released sugars (including muramic acid) to alditol acetates. Primary hospital filters contained 26.3 ± 10.0 ng of muramic acid/mg dust while secondary filters contained 5.3 ± 5.4 ng/mg. The level of inuramic acid in home air-conditioner dust was 31.7 ± 13.4 ng/mg. This study of dust collected from air-conditioners demonstrates the feasibility of chemical assessment of the microbial contamination of indoor air.
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  • 21
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 4 (1994), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
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  • 22
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 4 (1994), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: A numerical study has been carried out to predict the indoor air quality in a newly painted partitioned office and to assess the effect of ventilation rate and partition layout on the pre-ventilation time required to allow the contaminant concentration level to drop to an acceptable level. The air-flow pattern, the time history of the average contaminant concentration level in the occupied zone, and the pre-ventilation time were computed by a CFD code with a K-ε turbulence model.A displacement ventilation system, with different operating conditions, was used to remove contaminants in the office. The VB emission model, developed by Guo and Tichenor (1992), has been improved to include the influence of non-uniform concentration distribution on contaminant emission rate from the paints. The average contaminant (VOC) concentration levels in the occupied zone and in each chamber were recorded hourly until the average concentrations in the office were less then 0.0005 g/m3.It has been found that the non-uniform concentration distri- bution greatly influences the decay rate of VOC emissions. The time required for the average concentration in each chamber to reach the threshold level is different, since they are non-uniform. The time differences between the chambers having the highest and lowest concentrations were 3 to 8 hours. The results also show that the time required to reduce the concentration in the occupied zone to the threshold level is dependent on the partition layout. For the same ventilation rate, the required time is approximately 4-8 hours longer when using a side layout than when using a central layout.
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  • 23
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 4 (1994), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
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  • 24
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 4 (1994), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: A WHO/EURO working group met in Eilat, Israel, from 28 March to 4 April 1993, to assess the significance of risks to health associated with indoor radon, to develop a unified approach to control radon exposure, and to advise on the communication of associated health risks. A summary of the deliberations of this working group and its conclusions and recommendations are presented in this paper.
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  • 25
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 4 (1994), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Deciding between the different policy approaches available for reducing human exposures to indoor pollutants is an exceptionally complex task. These options can range from waiting until more definitive information is available to enacting regulatory standards, with many variations in between. This paper presents some of the factors policy-makers must consider in establishing indoor air quality policies, and the role researchers should play in ensuring that indoor air policies are based on the best available scientific information.
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  • 26
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: The development of odor emission rates from EU6 classified glass fiber bag filters was studied in four air-handling units (AHU), and emissions from the same kind of filters with EU3 classified polyester prefilters were studied in two units. The filters were loaded in six AHU in downtown Helsinki. The pressure drop was measured, and the odors of the filters were evaluated by a trained panel under laboratory conditions (T = 20°C, face velocity 1.0 m/s) every sixth week. The odor emissions of simultaneous atmospheric dust samples were also studied. The odor emissions of the filters rose during the first three months to a level where every third person would be dissatisfied. The emissions from coarse prefilters were similar to those from the more efficient filters without prefilters, and the emissions of the main filters were significantly lower if used with prefilters. This result indicates that the prefilters effectively protected the fine filters from odor-causing particles. The results of tests made with atmospheric samples agree with this result. Relative odor emissions were the highest in coarse fractions (〉 10.0 μm). The pressure drop increased with the particle mass collected on the ventilation filter, but it did not correlate well with the odor emission of the filter. Thus, pressure drop alone is not an adequate criterion for changing supply air filters when hygienic aspects are a concern.
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  • 27
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 4 (1994), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Full-scale residential house tests were conducted to evaluate the effects of organic emissions from a wood finishing product – wood stain – on indoor air quality (IAQ). The test house concentrations of three alkane species, nonane, decane, and undecane, were measured as a function of time after the application of the wood stain. It was found that the test house concentrations can be simulated by an integrated IAQ model which takes into consideration source, sink and ventilation effects. The alkane emissions were controlled by an evaporation-like process. Data analysis indicated that there were significant sink effects in the test house. Different sink strengths were estimated by the model for the three alkane species. An inverse relationship between the test house sink strength and the alkane volatility was found.
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  • 28
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 4 (1994), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Settled household dust samples were collected from twelve dwellings in urban areas during an annual winter heating period. Emission of compounds from settled household dust was analyzed under simulated hot surface conditions with a temperature range of 50–300°C. The compounds were analyzed and identified by thermal desorption—gas chromatographic-mass spectrometric technique. The organic emission from household dust was relatively low at temperatures below 70° C, increased appreciably above 100°C, and gained in strength at temperatures above 200°C. Desorption of adsorbed compounds is the main contribution to emissions, but at higher temperatures the thermal degradation seems to affect also the quantity and the quality of the emissions. The organic composition of household dust was found to be equal in quality at different sampling sites; the emissions consist of mainly aliphatic aldehydes (C6—C13), aliphatic carboxylic acids and their esters (C8 C18, C6–C30) and phthalates. Phosphate esters, branched alkanes, n-alkenes, n-alkanones, monoterpenes, aromatic hydrocarbons, and aromatic and aliphatic alcohols were also well represented groups in household dust samples. The potential sources of identified compounds are discussed.
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  • 29
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: The performance of sub-slab-ventilation (SSV) systems has been parametrically studied with a numerical model that was earlier compared successfully with experiment (Bonnefous et al., 1992). The model distinguishes between the sub-slab gravel and the underlying soil. It is used w examine system performance for the following system parameters: the permeability of the soil and of the sub-slab gravel, the magnitude of pressurization (or depressurization) applied by the SSV system, and the mode of SSV application (i.e. pressurization (SSP) or depressurization (SSD)). The mechanisms contributing to the successful performance of SSP and SSD systems are identified. For SSD systems, the mechanisms are (1) the inversion of the pressure gradient across the basement slab, and (2) the reduction of the radon concentration in the soil. For SSP systems, the mechanisms are (1) the elimination of convective flow of soil-gas from the soil into the sub-slab gravel by pressurization of the sub-slab region, (2) the reduction of the radon concentration in the soil, and (3) the suppression of diffusion of soil-gas from the soil into the sub-slab gravel by advective flow of air from the gravel bed into the subgravel soil. Numerical modeling demonstrates that placement of a sub-slab gravel layer substantially improves the SSV system performance. Except in the case of highly permeable soils, SSD systems are predicted to perform better than SSP systems. This prediction is consistent with reported field experience. The numerical model is used to elucidate the reasons for this difference in performance.
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  • 30
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 4 (1994), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
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  • 31
    Electronic Resource
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    Oxford, UK : Munksgaard International Publishers
    Indoor air 4 (1994), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
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  • 32
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: A procedure is developed for assessing the health effects of the emissions from building products. The procedure is based on:〈list xml:id="l1" style="custom"〉•emission rates measured in environment test chambers•a fixed standard room with fixed standard conditions•a maximum acceptable concentration in the indoor air of each of the chemical compounds emitted, Iv a maximum permissible contribution to Iv from building products.The procedure has two elements: evaluation of the emitted compound alone and evaluation of the compound together with other compounds and indoor air factors. The evaluation includes odour and health effects of the compounds.The procedure has been applied to the emission test results for two building products: a rubber floor covering, and a water-borne acrylic watt paint.Maximum acceptable indoor air concentrations are listed fin-selected chemical compounds emitted by these two materials.
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  • 33
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 4 (1994), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Heat, mass and momentum transfer takes place simultaneously in ventilated rooms. For accurate predictions of the indoor environment, all the environmental parameters that influence these transport phenomena should be taken into consideration. This paper introduces a method for a full assessment of indoor thermal comfort using computational fluid dynamics in conjunction with comfort models. A computer program has been developed which can be used for predicting thermal comfort indices such as thermal sensation and draught risk. The sensitivity of predicted comfort indices to environmental parameters is analysed for a mechanically ventilated office. It was found that when the mean radiant temperature was considered uniform in the office, the error in the predicted percentage of dissatisfied (PPD) could be as high as 7.5%. The prediction became worse when the mean radiant temperature was taken to be the same as air temperature point by point in the space. Moreover, disregarding the variation of vapour pressure in the space resulted in an error in PPD of abour 4% near the source of moisture generation.The importance of evaluating both thermal sensation and draught risk is also examined. It is concluded that in spaces with little air movement only the thermal sensation is needed for evaluation of indoor thermal comfort whereas in spaces with air movement induced by mechanical vantilation or air-conditioning systems both thermal sensation and draught risk should be evaluated.
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  • 34
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    Oxford, UK : Munksgaard International Publishers
    Indoor air 4 (1994), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: The objective of this study was to test the effectiveness of individual commercially available portable indoor air cleaning units in removing dust particulates, tobacco smoke particulate and vapor phase constituents (nicotine and vinyl pyridine), viable and total fungal spores, pollen, and gaseous contaminants (carbon monoxide[CO], nitrogen dioxide[NO2], and formaldehyde[HCHO]), in a clean air test chamber. The air cleaner chamber results presented here represent initial-use results. In general, High Efficiency Particulate Air (HEPA) and electrostatic precipitator systems demonstrated the highest efficiencies with respect to particulate, contaminants, followed closely by electret filter systems. Ionizers and ozone generators were least effective in particulate removal. Systems which included sufficient sorbent material (i.e. activated carbon or potassium permanganate) were marginally effective at gaseous contaminant removal. None of the systems tested were effective at carbon monoxide removal.Sensory testing was conducted to discern potential correlation between human perceptive response and measured air cleaner performance (with respect to tobacco smoke removal). An electret filter (EF) loaded with carbon sorbent received the best ratings with respect to odor strength, nasal irritation, eye irritation, and overall air acceptability.
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  • 35
    Electronic Resource
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    Oxford, UK : Munksgaard International Publishers
    Indoor air 4 (1994), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
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  • 36
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    Oxford, UK : Munksgaard International Publishers
    Indoor air 4 (1994), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
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  • 37
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    Oxford, UK : Munksgaard International Publishers
    Indoor air 4 (1994), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: A health and housing questionnaire was administered to children, ages 9-11, living in 24 communities in the United States and Canada. Logistic regression analysis examined the relationship between respiratory health symptoms (bronchitic, asthmatic and lower respiratory) and housing factors. The health risks (expressed as relative odds) were controlled for gender, parental asthma, parental chronic obstructive pulmonary disease and parental education, as well as between-city differences. Lower respiratory symptoms had significantly higher odds ratios reported in older homes (1.12), homes with smokers (1.24), air conditioners (1.14), air cleaners (1.37), and humidifiers (1.47). Home dampness (1.48) and the individual mold and water variables were all significantly associated with increased symptoms. Similar results were reported for bronchitic and asthmatic symptoms. While air conditioners and air cleaners were confounded with symptoms, humidifiers remained significant after controlling for childhood atopy.
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  • 38
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: In two case-referent studies the associations between questionnaire symptom reports, expressed as SBS (Sick Building Syndrome) in office workers or facial skin symptoms among VDT-workers, and physical data from offices in 160 buildings were investigated. The results show that low outdoor airflow rate and presence of certain pollution sources, such as copying machines, tended to be associated with an elevated prevalence of SBS. Buildings built or remodeled between 1977 and 1986, low-rise buildings with a horizontal roof and a foundation of the type “concrete slab on the ground”, as well as rooms with flourescent tube lighting with metal shields were also associated with higher SBS risks. A number of factors were associated with an overrepresentation of skin symptoms among VDT-workers such as type of foundation (concrete slab on the ground and crawlspace), the frequency of floor cleaning and type of lighting (fluorescent tubes with glass/plastic shields). It has not been possible to establish conclusive explanations for these associations. The difference in associations between building factors and S B S, and between building factors and skin symptoms among VD Tworkers points to different etiologies.
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  • 39
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    Oxford, UK : Munksgaard International Publishers
    Indoor air 4 (1994), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Ozone concentrations were measured in indoor and outdoor residential air during the summer of 1992. Six homes located in a New Jersey suburban area were chosen for analysis, and each home was monitored for 6 days under different ventilation and indoor combustion conditions. The 5-hour average ozone concentration outdoors over the monitoring period was 95 ± 36 ppbv. One third of the days exceeded the National Ambient Air Quality Standard (NAAQS), one-hour maximum concentration of 120 ppb. The mean indoor to outdoor (I/O) ratios of ozone concentration ranged from 0.22 ± 0.09 to 0.62 ± 0.11, depending upon ventilation rate and indoor gas combustion. The presence of indoor gas combustion can significantly decrease the I/O ratio. Because of the great amount of time that people spend indoors, the indoor residential exposures were estimated to account for 57% of the total residential exposures. One type of the possible gas-phase reactions for indoor ozone, the reaction of ozone with a volatile organic compound containing unsaturated carbon-carbon bonds, is discussed with some supporting evidence provided in the study.
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  • 40
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    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 4 (1994), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Indoor air quality models are commonly based on the assumption of instantaneous and complete air mixing within a zone. Such an assumption is not appropriate for all circumstances, such as investigating the utility of segregating smokers to reduce nonsmoker exposure to environmental tobacco smoke. This experimental study characterizes quantitatively the rate at which smoke from a cigarette disperses within an unoccupied, 31-m3, low air-exchange rate room under natural convection flow conditions. Sidestream smoke from a smoldering cigarette was simulated with a pulsed release of a tracer gas – a neutrally buoyant mixture of sulfur hexafluoride (SF6) in helium – above an electrically heated coil. During each experimental run, sequential air samples were collected remotely, using gas-tight syringes, from 41 locations within the room. After each run, these samples were analyzed for SF6 content using a gas chromatograph with an electron-capture detector. Duplicate runs were conducted under three conditions: nearly isothermal surfaces; convection from a 500–watt heater; and convection from incoming solar radiation. Characteristic mixing times ranged from 7–10 minutes for the solar radiation case to 80–100 minutes for the nearly isothermal case.
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  • 41
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    Oxford, UK : Munksgaard International Publishers
    Indoor air 4 (1994), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
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  • 42
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    Oxford, UK : Munksgaard International Publishers
    Indoor air 4 (1994), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
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  • 43
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A lateral sample modulation technique is presented to measure simultaneously lateral friction forces and topological features with an atomic force microscope (AFM). The employed technique allows one to use an AFM without any additional displacement sensor. This dynamic detection scheme is well suited for AFMs equipped with a fiber-optic displacement sensor. The technique and the mechanism of the contrast formation are discussed. The performance of the microscope is demonstrated by imaging flat surfaces and large corrugated films as well as low friction samples.
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  • 44
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A computer-controlled rotating polarizer ellipsometer, operating in the infrared spectral region between 3.00 and 3.75 μm, has been developed for in situ characterization of amorphous hydrocarbon (a-C:H) thin films, deposited from methane in a rf plasma-enhanced chemical vapor deposition reactor. Spectroscopic IR ellipsometry permits insight into the chemical bonding structure of a-C:H coatings by the nondestructive detection of infrared stimulated C:H stretch vibrations. It is shown that the sp2CHx/sp3 CHx ratio, the content of bonded hydrogen, the infrared linewidth, and the real refractive index of the films depend on the negative self-bias voltage, which is formed at the samples during the deposition process. A transition from a-C:H films with polymerlike properties to hard a-C:H films was attained at a self-bias voltage of approximately −75 V.
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  • 45
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We present a new method for measuring time-resolved photoluminescence on a time scale of microseconds and milliseconds using correlational analysis, and we demonstrate it to work on porous silicon and GaP:Fe. We modulate the pumping laser with a pseudorandom binary sequence which yields correlational properties similar to white noise. The photoluminescence decay is computed via cross correlation of the detector signal with the pumping sequence. The presented method is highly sensitive, simple in application, and inexpensive.
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  • 46
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    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2896-2900 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We present a methodology to retrieve the thermal diffusivity of bulk homogeneous samples based on a set of simple linear relations that exist between two measurable magnitudes in modulated photothermal experiments. The influence of the photothermal parameters involved (exciting beam radius and height and radius of the probe beam) is evaluated to assert the validity of the linear relations. Specifically, we discuss the thermoreflectance and mirage techniques and their more convenient use and method, depending on the kind of sample to analyze (solid, liquid, gas), to obtain the thermal diffusivity.
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  • 47
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A commercially available flat flame burner with a sintered porous bronze disk was used to stabilize premixed H2/air flames at atmospheric pressure. Temperatures for various stoichiometries, flow rates, and heights above the burner disk have been measured by coherent anti-Stokes Raman scattering with an accuracy of ≈2.5%. The corresponding exhaust gas compositions have been derived from equilibrium calculations. This burner together with the data presented in this article can be used for the verification or calibration of a variety of measuring techniques in combustion research.
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  • 48
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have developed a high-resolution ac susceptometer that uses a rf superconducting quantum interference device to directly measure the flux coupled into a superconducting detection coil from a sample's changing magnetic moment in an applied ac field. The system operates in a frequency range from 0.01 to 1500 Hz and an applied ac field range of 0.1–400 μT with a sensitivity of about 5×10−12 A m2 for magnetic moment measurement, and at a reduced sensitivity down to 0.001 Hz. The instrument is based on an existing dc magnetometer system and uses that system's temperature control and dc superconducting magnet to allow operation over a temperature range from 2 to 400 K and in applied dc fields of ±5.0 T. During a measurement all operations are controlled automatically by computer from a menu-driven software system, with user input required only on initiation of a measurement sequence. Both real and imaginary components of the ac susceptibility can be determined.
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  • 49
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    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2653-2657 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A microwave impedance bridge covering from 8.2 to 12.4 GHz used for measuring complex dielectric constants over a wide temperature range is described. This apparatus is suited for materials formed into solid posts having different cross sections. The effective diameters for use in the analysis of circular, elliptical, or rectangular cross-section posts are presented. The effective diameters are applied to determine the complex dielectric constant of rectangular-shaped conducting polymer film. The frequency and temperature dependence of the dielectric constant and conductivity are presented, and compared with those obtained using a microwave cavity perturbation technique at 6.5 GHz. The bridge results are well suited for independent determination of the depolarization factor of a rectangular post for use in analysis of results of the cavity perturbation method.
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  • 50
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    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2667-2671 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Problems concerning the response of microwave radiometers to the polarization of incident radiation are examined. Particular attention is given to their consequences in experiments measuring the intensity anisotropy of the cosmic background radiation. Considered in detail are instrumental configurations in which metal reflectors are used to redirect the antenna beam. Some effects introduced by such reflectors are calculated and modelled for different values of some relevant parameters, in order to evaluate their contribution to instrumental errors. The analysis of a real experiment is then considered. It is shown that such mechanisms, if ignored, can seriously affect the measurements.
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  • 51
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    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2953-2956 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A method of preparing ion beams of known mass and charge for time-of-flight scattering and recoiling spectrometry (TOF-SARS) using sequential deflection pulses (SDP) has been developed. A double-pulsing sequence is described in which the first pulse is used to create ion pulses and the second pulse, triggered after a suitable delay, allows only the species of interest to be transmitted to the target. A mass resolution of m/Δm=3–5 was achieved with the present system, eliminating the need for conventional mass resolution devices when high mass resolution is not required. Examples of the direct separation of Ar+ and Ar2+ ions from an ion beam and separation of Ar+ and Ar2+ scattering and recoiling spectra from an indium phosphide (InP) surface are provided.
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  • 52
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    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2947-2952 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The mean plasma potential was measured on the LBL advanced electron cyclotron resonance (AECR) ion source for a variety of conditions. The mean potentials for plasmas of oxygen, argon, and argon mixed with oxygen in the AECR were determined. These plasma potentials are positive with respect to the plasma chamber wall and are on the order of tens of volts. Electrons injected into the plasma by an electron gun or from an aluminum oxide wall coating with a very high secondary electron emission reduce the plasma potential as does gas mixing. A lower plasma potential in the AECR source coincides with enhanced production of high charged state ions indicating longer ion confinement times. The effect of the extra electrons from external injection or wall coatings is to lower the average plasma potential and to increase the neτi of the ECR plasma. With sufficient extra electrons, the need for gas mixing can be eliminated or reduced to a lower level, so the source can operate at lower neutral pressures. A reduction of the neutral pressure decreases charge exchange between ions and neutrals and enhances the production of high charge state ions. An aluminum oxide coating results in the lowest plasma potential among the three methods discussed and the best source performance.
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  • 53
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    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2019-2022 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A fast and low cost pressure monitor is presented that can easily be mounted on pulsed molecular beam sources and allows one to measure the pressure pulse in the source during operation. The pressure monitor has a time resolution of 10 μs and is especially suited for the control of gas dynamics and nucleation in pulsed laser vaporization cluster sources.
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  • 54
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The Holifield Radioactive Ion Beam Facility now under construction at the Oak Ridge National Laboratory will use the 25 MV tandem accelerator for the acceleration of radioactive ion beams to energies appropriate for research in nuclear physics; negative ion beams are, therefore, required for injection into the tandem accelerator. Because charge exchange is an efficient means for converting initially positive ion beams to negative ion beams, both positive and negative ion sources are viable options for use at the facility. The choice of the type of ion source will depend on the overall efficiency for generating the radioactive species of interest. Although direct-extraction negative ion sources are clearly desirable, the ion formation efficiencies are often too low for practical consideration; for this situation, positive ion sources, in combination with charge exchange, are the logical choice. The high-temperature version of the CERN-ISOLDE positive ion source has been selected and a modified version of the source designed and fabricated for initial use at the facility because of its low emittance, relatively high ionization efficiencies, and species versatility, and because it has been engineered for remote installation, removal, and servicing as required for safe handling in a high-radiation-level ISOL facility. The source will be primarily used to generate ion beams from elements with intermediate to low electron affinities. Prototype plasma-sputter negative ion sources and negative surface-ionization sources are under design consideration for generating radioactive ion beams from high-electron-affinity elements. The design features of these sources and expected efficiencies and beam qualities (emittances) will be described in this report.
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  • 55
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    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2023-2027 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe the design, construction, and implementation of a low-pass energy filter for use with a liquid metal ion source (LMIS) cluster deposition system. When combined with deceleration of cluster ions to a surface for landing, this filter provides bandpass energy selectivity for high resolution mass separation of clusters produced by the LMIS. We also present results of our initial testing, which shows the filter has an experimental relative energy resolution of less than 0.3%.
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  • 56
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    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2028-2033 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have measured atomic hydrogen velocity distributions in an effusive beam coming out of a rf discharge dissociator by using a magnetic deflection technique. Dissociator pressures varied between 0.028 and 0.340 Torr. At low dissociator pressures the measured atomic velocity distributions were narrower than the expected beam Maxwellians; at higher pressures they were indistinguishable from beam Maxwellians at the dissociator wall temperature, indicating full thermalization of the atoms prior to exiting the dissociator. Monte Carlo simulations of the thermalization process within the dissociator reproduce these results, and point out the important role of vibrational excitation of the background hydrogen molecules as an energy loss mechanism. Our results are significant when designing magnetic state selectors for spin- or hyperfine-polarized atomic hydrogen beams.
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  • 57
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A novel type of source for excited species of cesium is described. It employs an effusive flux to the back of a metal foil, with the excited-state emission from the other side of the covered foil. The foil is kept at a temperature of 1000–1900 K by direct heating with an electric current. From the foil, various excited species of ions and atoms, some of which are rather short lived, are emitted at large densities. Only the species observed at a distance of at least 40 mm from the source emitter are of interest here. Excited species are observed by both steady-state and pulsed field ionization, at current densities up to 10−4 A cm−2, which is several percent of the total beam flux. Positive and negative excited ions can also be observed in the flux from the source, by their ability to emit electrons with energy-independent efficiency at impact on surfaces. The corresponding flux densities are up to 10−5 and 10−4 A cm−2, respectively. Doubly excited atoms can be observed as Cs2+ after field ionization in a mass spectrometer. They also produce ions after energy transfer to small molecules.
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  • 58
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Measurements of electron temperature using electron cyclotron emission (ECE) may be contaminated by density effects in plasmas with low optical depth. ECE intensity fluctuations in these plasmas will include a component dependent on density fluctuations as well. Correlation measurements, which will extract the temperature fluctuations from the dominant radiometer thermal noise, will include correlated density fluctuations in the result. In tokamak core plasmas, where normalized density fluctuations have been measured to be about 1%, this effect can be considerable (∼100%) at low levels of temperature fluctuations. However, at "relevant'' levels, defined by the amount of anomalous heat transport, these effects are reduced, at least in TEXT-U. While exact interpretation of temperature fluctuation amplitudes is compromised, statements regarding the relevance of the inferred temperature fluctuation amplitudes can be made relatively unambiguously.
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  • 59
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    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2049-2055 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Stigmatic spectroscopic observations of laser produced plasma have been performed in the 50–200 A(ring) spectral interval. The purpose was to demonstrate the good instrumental performances of an intensified bidimensional detector installed on a stigmatic soft x-ray spectrometer. The latter is the combination of a grating spectrograph in Rowland circle mount and a toroidal mirror, both working at grazing incidence. The detector is composed of a scintillator on the spectrograph focal circle, an image intensifier, and a charge coupled device. The resulting spatial and spectral resolution are of 60 μm and 1000, respectively. The observations show a marked improvement in term of dynamic range, sensitivity, ease of operation, and real-time data presentation in comparison to both traditional photographic film and photodiode array detection technique.
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  • 60
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    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3028-3029 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The beam-bending method is very useful for the viscosity determination of glasses, but the time spent to run the measurement is usually very long. The present note describes the performance of an improved beam-bending viscosimeter at the support stand and loading rod to get the faster measurements of high viscosity glasses with better reliability and precision. The testing time was reduced from 8 to less than 4 hours to run one measurement at three different temperatures (1100, 1200, and 1300 °C), with the precision of almost one order of magnitude better (±0.01 for 1g η in poise).
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  • 61
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    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3030-3031 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Two simple three-electrode spark gaps have been constructed to operate at high voltages up to 30 kV for use in a gas laser triggering system. The performance of each spark gap has been tested in a nitrogen laser system designed for this purpose, and the results are described in this report. The pressure-controlled spark gap has shown better results in terms of stability and lifetime, and it is highly reliable for high repetition rate switching.
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  • 62
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3032-3033 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An analog instrumentation for estimating dimensions of chaotic dynamical systems has been developed. The technique employs time series of the Poincaré points successively displayed on the screen of an oscilloscope. It provides a rapid way to estimate the pointwise dimension from a single variable directly in an experiment. The instrumentation is easy to build and is convenient to employ. We have tested it by applying to periodic and quasiperiodic oscillators, and have verified by means of the fractal two-dimensional Poincaré map, simulated from the Duffing–Holmes differential equation. The measured values well agree with the computer calculated ones.
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  • 63
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3034-3035 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In time resolved measurements of neutron emission, the most common practice is to use a plastic scintillator coupled to a fast photomultiplier. There are different ways of coupling the light emitted by the scintillator to the photomultiplier (PM), according to the size and the shape of the scintillator. Some of the more usual coupling geometries are light pipes, Plexiglas cones with silvered walls or mirror "huts'' facing the PM window.
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  • 64
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    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3038-3039 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This paper describes a simple portable mechanical structure to support a medium size cryostat. The structure can provide adequate support for an helium-3 cryostat with an 8 T magnet while the Dewar can be stored between experiment in a pit hole area below the temporary structure.
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  • 65
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3036-3037 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A simple technique is demonstrated for preventing microchannel plate (MCP) response to scattered laser light in a multiphoton ionization experiment. The MCP is gated on after the laser pulse, with a turn-on time of less than 1 μs, by switching its cathode from 0 to −1900 V. The high-voltage pulse circuit uses power MOSFETs and was designed according to the procedure of Baker and Johnson [Electron. Lett. 29, 56 (1993)].
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  • 66
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    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 1017-1018 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A semi-analytic form for the axial buckling force of a multistage vibration-isolation stack for gravitational radiation detectors is deduced. This is another version of Euler's formula for simple pillars and gives a reference value both in design of isolation stacks and in numerical analysis for more complicated situations.
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  • 67
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 1019-1020 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Described is the design for a new electrochemical cell for in situ studies with the atomic force microscope. Improvements over presently used cells include an axially symmetric electrode geometry, large counter electrode, and the ability to incorporate a standard reference electrode close to the working electrode.
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  • 68
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3044-3045 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The frequency dependence of the complex ac susceptibility of a magnetic conducting sphere is derived. The resultant formulas can be used to determine electrical conductivity from ac susceptibility measurements, to calculate ac susceptibilities of standard samples for the calibration of ac susceptometers, and to analyze ac losses in materials research.
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  • 69
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2433-2459 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe here several types of mass spectrometry in which the mass selectivity is combined with a highly selective laser ionization method to achieve both high sensitivity and very high selectivity. These methods combine the most sensitive and highly selective laser ionization methods with mass selectivity in order to improve on both the sensitivity and the Z and A selectivity previously achievable in detecting atomic species. Applications of these methods include the dating of geophysical specimens, the on line analysis of rare short-lived isotopes produced in high-energy collisions, the detection of low levels of heavy metals or radioactive isotopes in biological samples, the detection of impurities in ultrapure materials, and a host of other applications. Because some versions of this method offer sensitivity to a hundred atoms of a particular isotope of an element in a macroscopic sample, there are new possibilities for fundamental studies of rare events. Several types of facilities for elemental and isotopic analysis will be described.
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  • 70
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2460-2463 
    ISSN: 1089-7623
    Source: AIP Digital Archive