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1.
Room temperature sterilization of surfaces and fabrics with a One Atmosphere Uniform Glow Discharge Plasma 总被引:8,自引:0,他引:8
K Kelly-Wintenberg T C Montie C Brickman J R Roth A K Carr K Sorge L C Wadsworth P P Y Tsai 《Journal of industrial microbiology & biotechnology》1998,20(1):69-74
We report the results of an interdisciplinary collaboration formed to assess the sterilizing capabilities of the One Atmosphere
Uniform Glow Discharge Plasma (OAUGDP). This newly-invented source of glow discharge plasma (the fourth state of matter) is
capable of operating at atmospheric pressure in air and other gases, and of providing antimicrobial active species to surfaces
and workpieces at room temperature as judged by viable plate counts. OAUGDP exposures have reduced log numbers of bacteria,
Staphylococcus aureus and Escherichia coli, and endospores from Bacillus stearothermophilus and Bacillus subtilis on seeded solid surfaces, fabrics, filter paper, and powdered culture media at room temperature. Initial experimental data
showed a two-log10 CFU reduction of bacteria when 2 × 102 cells were seeded on filter paper. Results showed ≥3 log10 CFU reduction when polypropylene samples seeded with E. coli (5 × 104) were exposed, while a 30 s exposure time was required for similar killing with S. aureus-seeded polypropylene samples. The exposure times required to effect ≥6 log10 CFU reduction of E. coli and S. aureus on polypropylene samples were no longer than 30 s. Experiments with seeded samples in sealed commercial sterilization bags
showed little or no differences in exposure times compared to unwrapped samples. Plasma exposure times of less than 5 min
generated ≥5 log10 CFU reduction of commercially prepared Bacillus subtilis spores (1 × 106); 7 min OAUGDP exposures were required to generate a ≥3 log10 CFU reduction for Bacillus stearothermophilus spores. For all microorganisms tested, a biphasic curve was generated when the number of survivors vs time was plotted in dose-response cures. Several proposed mechanisms of killing at room temperature by the OAUGDP are discussed.
Received 06 June 1997/ Accepted in revised form 01 November 1997 相似文献
2.
Wind‐mediated horseweed (Conyza canadensis) gene flow: pollen emission,dispersion, and deposition
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Haiyan Huang Rongjian Ye Meilan Qi Xiangzhen Li David R. Miller Charles Neal Stewart David W. DuBois Junming Wang 《Ecology and evolution》2015,5(13):2646-2658
Horseweed (Conyza canadensis) is a problem weed in crop production because of its evolved resistance to glyphosate and other herbicides. Although horseweed is mainly self-pollinating, glyphosate-resistant (GR) horseweed can pollinate glyphosate-susceptible (GS) horseweed. To the best of our knowledge, however, there are no available data on horseweed pollen production, dispersion, and deposition relative to gene flow and the evolution of resistance. To help fill this knowledge gap, a 43-day field study was performed in Champaign, Illinois, USA in 2013 to characterize horseweed atmospheric pollen emission, dispersion, and deposition. Pollen concentration and deposition, coupled with atmospheric data, were measured in a source field (180 m by 46 m) and its surrounding areas up to 1 km downwind horizontally and up to 100 m vertically. The source strength (emission rate) ranged from 0 to 140 pollen grains per plant per second (1170 to 2.1×106 per plant per day). For the life of the study, the estimated number of pollen grains generated from this source field was 10.5×1010 (2.3×106 per plant). The release of horseweed pollen was not strongly correlated to meteorological data and may be mainly determined by horseweed physiology. Horseweed pollen reached heights of 80 to100 m, making long-distance transport possible. Normalized (by source data) pollen deposition with distance followed a negative-power exponential curve. Normalized pollen deposition was 2.5% even at 480 m downwind from the source edge. Correlation analysis showed that close to or inside the source field at lower heights (≤3 m) vertical transport was related to vertical wind speed, while horizontal pollen transport was related to horizontal wind speed. High relative humidity prevented pollen transport at greater heights (3–100 m) and longer distances (0–1000 m) from the source. This study can contribute to the understanding of how herbicide-resistance weeds or invasive plants affect ecology through wind-mediated pollination and invasion. 相似文献
3.
Potential canopy influences on the isotopic composition of nitrogen and sulphur in atmospheric deposition 总被引:7,自引:0,他引:7
Isotopic studies of nitrogen and sulphur inputs to plant/soil systems commonly rely on limited published data for the 15N/14N and 34S/32S ratios of nitrate, ammonium and sulphate in rainfall. For systems with well-developed plant canopies, however, inputs of
these ions from dry deposition or particulates may be more important than rainfall. The manner in which isotopic fractionation
between ions and gases may lead to dry deposition and particulates having 15N/14N or 34S/32S ratios different from those of rainfall is considered. Data for rainfall and throughfall in coniferous plantations are then
discussed, and suggest that: (1) in line with expectations, nitrate washed from the canopy has 15N/14N ratios higher than those in rainfall; (2) the 15N/14N ratios of ammonium washed from the canopy are variable, with high ratios being found for canopies of higher pH in conditions
of elevated ambient ammonia gas concentrations; and (3) in accord with expectations and previous work, 34S/32S ratios of sulphate washed from the canopy are not substantially different from those in rainfall. The study suggests that
if atmospheric inputs are relevant to isotopic studies of the sources of nitrogen for canopied systems, then confident interpretation
will require analysis of these inputs.
Received: 3 March 1996 / Accepted: 28 September 1996 相似文献
4.
Iwajlo M. Kandjov 《International journal of biometeorology》1997,40(2):91-94
The thermal properties of atmospheric air surrounding the human body at various altitudes are characterized with a system
of parameters. This system comprises resistance of the air to convective heat transfer h
c
–1, °C (W/m2)−1 and to water vapour transfer h
D
–1, s/m. The concept of ’evaporative resistance’h
e
–1, hPa (W/m2)−1) following the similarity of the processes is introduced. In obtaining the altitude dependencies of investigated paramters,
a respective heat transfer equation expressing the rate of heat exchange at the boundary body surface – ambient air is applied.
The use of the body thermal state of the established altitude dependencies is discussed. The concept of ’thermal stability’
related to the evaporative resistance parameter h
e
–1 is introduced. This parameter is assumed as: (1) an indicator of the human body thermal stability and (2) distributor and
predictor of environmental influence on the body thermal state.
Received: 5 January 1996 / Accepted 5 November 1996 相似文献
5.
The behaviour of boron (B) and its fate in the environment remains in many respects obscure. The major B sources and fluxes
seem to have been identified, although there are many uncertainties about the magnitude and importance of each; published
evaluations vary greatly. Little is known about B speciation of living matter-bearing formations, i.e. soils, natural waters,
and sediments. Many authors suppose that B in nature occurs only as oxo-compounds, although, natural inorganic and organic
B compounds and complexes have been described. Moreover, the most common approach to B biogeochemistry in terms of inorganic
B compounds (as boric acid and borates) seems to oversimplify the matter. Data on the physiological functions of B are fragmentary
and often contradictory. Some data exists on endemic symptoms and diseases among humans and grazing cattle that are supposedly
triggered by B abundance in the natural environment. Unfortunately, the published data are scarce and vague. In this paper,
we review the up-to date references on B sources, turnover, and speciation in the environment and the element potential impact
on health. 相似文献
6.
The sulfur content in different parts of the twig the same year is different, i.e. leaf bark wood. Variation exists in different tree species in seasons and appears to be in positive retation with atmospheric SO2 concentration. The bark of hibernal twig of the deciduous leaves possesses significant capacity of sulfur absorption which is interrelated with the total opening of lenticelle and is also influenced by the surface structure of stems as well. This paper presents a regression equation and a calculation chart for monitoring SO2 pollution by sulfur content detected in the bark in winter at some regions in Shenyang. The results are in concert with those determinated by the physical-chemical methods. 相似文献
7.
Numerous studies focus on the measurement of conductances for CO2 transfer in plants and especially on their regulatory effects on photosynthesis. Measurement accuracy is strongly dependent on the model used and on the knowledge of the flow of photochemical energy generated by light in chloroplasts. The only accurate and precise method to quantify the linear electron flux (responsible for the production of reductive energy) is the direct measurement of O2 evolution, by 18O2 labelling and mass spectrometry. The sharing of this energy between the carboxylation (P) and the oxygenation of photorespiration (PR) depends on the plant specificity factor (Sp) and on the corresponding atmospheric concentrations of CO2 and O2 ( André, 2013). The concept of plant specificity factor simplifies the equations of the model. It gives a new expression of the effect of the conductance (g) between atmosphere and chloroplasts. Its quantitative effect on photosynthesis is easy to understand because it intervenes in the ratio of the plant specificity factor (Sp) to the specificity of Rubisco (Sr). Using this ‘simple’ model with the data of 18O2 experiments, the calculation of conductance variations in response to CO2 and light was carried out. 相似文献
8.
Fengxue Gu Yuandong Zhang Mei Huang Bo Tao Rui Guo Changrong Yan 《Ecology and evolution》2017,7(17):6736-6746
The response of ecosystems to different magnitudes of climate warming and corresponding precipitation changes during the last few decades may provide an important reference for predicting the magnitude and trajectory of net primary productivity (NPP) in the future. In this study, a process‐based ecosystem model, Carbon Exchange between Vegetation, Soil and Atmosphere (CEVSA), was used to investigate the response of NPP to warming at both national and subregional scales during 1961–2010. The results suggest that a 1.3°C increase in temperature stimulated the positive changing trend in NPP at national scale during the past 50 years. Regardless of the magnitude of temperature increase, warming enhanced the increase in NPP; however, the positive trend of NPP decreased when warming exceeded 2°C. The largest increase in NPP was found in regions where temperature increased by 1–2°C, and this rate of increase also contributed the most to the total increase in NPP in China's terrestrial ecosystems. Decreasing precipitation depressed the positive trend in NPP that was stimulated by warming. In northern China, warming depressed the increasing trend of NPP and warming that was accompanied by decreasing precipitation led to negative changing trends in NPP in large parts of northern China, especially when warming exceeded 2°C. However, warming stimulated the increase in NPP until warming was greater than 2°C, and decreased precipitation helped to increase the NPP in southern China. 相似文献
9.
Study of bioaerosols and site influence in the La Plata area (Argentina) using conventional and DNA (fingerprint) based methods 总被引:1,自引:0,他引:1
The present study approaches the characterization of seasonal samples of bioaerosols taken during 2005–2006 in rural, urban,
industrial, coastal and residential sites within La Plata area, Buenos Aires, Argentina. Culturable airborne fungal and bacterial
communities were collected on DG18 agar and R2 Agar plates respectively, using a single-stage SKC sampling device. Fungal
genera were identified based on their micro- and macro-morphological characteristics. Bacterial populations were analyzed
by denaturing gradient gel electrophoresis (DGGE) of PCR 16SrDNA bacterial amplification. Geometric mean concentration of
bacteria and fungi ranged from 10 to 103 CFU m−3 and were comparable with those from other reports. No differences were observed among sites for fungi and Cladosporium sp. was predominant, with 85.7% of total concentration counts; secondary genera that contributed were Alternaria (6.7%), Penicillium (1.8%), Aspergillus (1.3%), Epicoccum (1.0%) and the group of yeasts (1.9%). The dominance of Cladosporium in all sites suggests that the most abundant fungal aerosol was neither significantly affected nor primarily generated by
any anthropogenic area source more than the natural ambience present in the La Plata area. With regard to bacteria, the results
showed on several occasions differences in concentration among sites during sampling events, but these differences were not
observed when the community structure was analyzed by means of DGGE. Bacterial DGGE banding profiles from all sites revealed
the existence of a relatively diversified, culture-based airborne community. Construction of similarity dendrograms exposed
a distribution of site samples in which replicates intra-site equalled those encountered among sites, rendering substantial
inference of site distinction unfeasible. 相似文献
10.
Donald W. Thayer Glenn Boyd Wayne S. Muller Carol A. Lipson Walter C. Hayne Steven H. Baer 《Journal of industrial microbiology & biotechnology》1990,5(6):383-390
Summary The ionizing radiation resistances of sixSalmonella species were examined. The experimental variables were the suspending medium, the presence or absence of air, and the temperature during the irradiation process.S. typhimurium ATCC 14028,S. enteritidis ATCC 9186,S. newport ATCC 6962,S. dublin ATCC 15480,S. anatum ATCC 9270, andS. arizonae ATCC 29933 were suspended in phosphate buffer (0.1 M, pH 7.0), brain heart infusion broth (BHI) or mechanically deboned chicken and exposed to gamma radiation from cesium-137 at 0.12 kGy per min. The radiation resistance of theSalmonella increased approximately two-fold when assayed in sterile mechanically deboned chicken rather than in buffer or BHI. The average radiation (0.30 to 1.20 kGy) D-value for all sixSalmonella strains was 0.56 kGy in mechanically deboned chicken.S. enteritidis was significantly more resistant to ionizing radiation than the other five strains ofSalmonella tested on mechanically deboned chicken. The temperature of irradiation but not the presence or absence of air significantly influenced the survival ofS. typhimurium andS. enteritidis in mechanically deboned chicken. Treatment of chicken meat with ionizing radiation would be an effective means for control ofSalmonella contamination. 相似文献