scholarly journals Laboratory study of bioaerosols: Traditional test systems, modern approaches, and environmental control

2019 ◽  
Vol 54 (5) ◽  
pp. 585-600
Author(s):  
Joshua L. Santarpia ◽  
Shanna Ratnesar-Shumate ◽  
Allen Haddrell
Author(s):  
K.C. Newton

Thermal effects in lens regulator systems have become a major problem with the extension of electron microscope resolution capabilities below 5 Angstrom units. Larger columns with immersion lenses and increased accelerating potentials have made solutions more difficult by increasing the power being handled. Environmental control, component choice, and wiring design provide answers, however. Figure 1 indicates with broken lines where thermal problems develop in regulator systemsExtensive environmental control is required in the sampling and reference networks. In each case, stability better than I ppm/min. is required. Components with thermal coefficients satisfactory for these applications without environmental control are either not available or priced prohibitively.


Author(s):  
D.E. Brownlee ◽  
A.L. Albee

Comets are primitive, kilometer-sized bodies that formed in the outer regions of the solar system. Composed of ice and dust, comets are generally believed to be relic building blocks of the outer solar system that have been preserved at cryogenic temperatures since the formation of the Sun and planets. The analysis of cometary material is particularly important because the properties of cometary material provide direct information on the processes and environments that formed and influenced solid matter both in the early solar system and in the interstellar environments that preceded it.The first direct analyses of proven comet dust were made during the Soviet and European spacecraft encounters with Comet Halley in 1986. These missions carried time-of-flight mass spectrometers that measured mass spectra of individual micron and smaller particles. The Halley measurements were semi-quantitative but they showed that comet dust is a complex fine-grained mixture of silicates and organic material. A full understanding of comet dust will require detailed morphological, mineralogical, elemental and isotopic analysis at the finest possible scale. Electron microscopy and related microbeam techniques will play key roles in the analysis. The present and future of electron microscopy of comet samples involves laboratory study of micrometeorites collected in the stratosphere, in-situ SEM analysis of particles collected at a comet and laboratory study of samples collected from a comet and returned to the Earth for detailed study.


2008 ◽  
Vol 13 (4) ◽  
pp. 239-247 ◽  
Author(s):  
David De Cremer ◽  
Barbara C. Schouten

The present research examined the idea that the effectiveness of apologies on promoting fairness perceptions depends on how meaningful and sincere the apology is experienced. More precisely, it was predicted that apologies are more effective when they are communicated by an authority being respectful to others. A study using a cross-sectional organizational survey showed that an apology (relative to giving no apology) revealed higher fairness perceptions, but only so when the authority was respectful rather than disrespectful. In a subsequent experimental laboratory study the same interaction effect (as in Study 1) on fairness perceptions was found. In addition, a similar interaction effect also emerged on participants’ self-evaluations in terms of relational appreciation (i.e., feeling valued and likeable). Finally, these self-evaluations accounted (at least partly) for the interactive effect on fairness perceptions.


2009 ◽  
Author(s):  
Jing Guo ◽  
Louis Tay ◽  
Fritz Drasgow
Keyword(s):  

1979 ◽  
Author(s):  
Ronald M. Robertson ◽  
James W. Greene ◽  
Donald W. Maxwell ◽  
Carl E. Williams
Keyword(s):  

2019 ◽  
Author(s):  
Marko J. Spasojevic ◽  
Sören Weber1

Stable carbon (C) and nitrogen (N) isotopes in plants are important indicators of plant water use efficiency and N acquisition strategies. While often regarded as being under environmental control, there is growing evidence that evolutionary history may also shape variation in stable isotope ratios (δ13C and δ15N) among plant species. Here we examined patterns of foliar δ13C and δ15N in alpine tundra for 59 species in 20 plant families. To assess the importance of environmental controls and evolutionary history, we examined if average δ13C and δ15N predictably differed among habitat types, if individual species exhibited intraspecific trait variation (ITV) in δ13C and δ15N, and if there were a significant phylogenetic signal in δ13C and δ15N. We found that variation among habitat types in both δ13C and δ15N mirrored well-known patterns of water and nitrogen limitation. Conversely, we also found that 40% of species exhibited no ITV in δ13C and 35% of species exhibited no ITV in δ15N, suggesting that some species are under stronger evolutionary control. However, we only found a modest signal of phylogenetic conservatism in δ13C and no phylogenetic signal in δ15N suggesting that shared ancestry is a weaker driver of tundra wide variation in stable isotopes. Together, our results suggest that both evolutionary history and local environmental conditions play a role in determining variation in δ13C and δ15N and that considering both factors can help with interpreting isotope patterns in nature and with predicting which species may be able to respond to rapidly changing environmental conditions.


1969 ◽  
Vol 62 (1_Suppl) ◽  
pp. S95-S112 ◽  
Author(s):  
A. H. W. M. Schuurs

ABSTRACT Various techniques for sensitising erythrocytes and latex particles with gonadotrophins, particularly with HCG, are described. The haemagglutination inhibition reactions are generally interpreted by means of »erythrocyte settling patterns«. By a new method of evaluating these patterns a relatively precise quantitative determination is possible. Latex agglutination inhibition reactions on slides are particularly suitable as rapid qualitative tests. In cases where the maximum attainable sensitivity of the agglutination inhibition tests is insufficient, e. g. for determining LH concentrations in urine, the hormone in the test fluid has to be concentrated or extracted. An alternative method is a modified haemagglutination inhibition test for large volumes which is applicable to unconcentrated urine. Due to non-specific inhibitions the above-mentioned tests cannot be applied to unprocessed serum. Agglutination inhibition tests with HCG are already well advanced, pregnancy diagnosis being their main application. Now that highly purified HCG is available, a satisfactory specificity for these tests can be attained. If the immune system for HCG is used for estimating LH, it has to meet additional specificity requirements. Furthermore, the measure of cross-reaction and the choice of standard merit special attention. Finally, a literature survey is given of test systems in which LH and FSH were used as antigens.


2016 ◽  
Vol 3 (1) ◽  
pp. 43-48 ◽  
Author(s):  
V. Patyka ◽  
L. Butsenko ◽  
L. Pasichnyk

Aim. To validate the suitability of commercial API 20E test-system (bioMerieux) for the identifi cation and characterization of facultative gram-negative phytopathogenic bacterial isolates. Methods. Conventional mi- crobiological methods, API 20E test-system (bioMerieux) according to the manufacturer’s instructions. Re- sults. The identifi cation results for Erwinia amylovora, Pectobacterium carotovorum and Pantoea agglome- rans isolates were derived from the conventional and API 20E test systems, which, were in line with the literature data for these species. The API 20E test-system showed high suitability for P. agglomerans isolates identifi cation. Although not all the species of facultatively anaerobic phytopathogenic bacteria may be identi- fi ed using API 20E test-system, its application will surely allow obtaining reliable data about their physiologi- cal and biochemical properties, valuable for identifi cation of bacteria, in the course of 24 h. Conclusions. The results of tests, obtained for investigated species while using API 20E test-system, and those of conventional microbiological methods coincided. The application of API 20E test-system (bioMerieux) ensures fast obtain- ing of important data, which may be used to identify phytopathogenic bacteria of Erwinia, Pectobacterium, Pantoea genera.


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