Examination of ultraviolet germicidal radiation for inactivating microorganisms in melted snow and ice samples

2021 ◽  
Author(s):  
Fumio Nakazawa ◽  
Kumiko Goto-Azuma
Keyword(s):  
Size Distribution ◽  
Water Samples ◽  
Microbial Growth ◽  
Particle Concentration ◽  
Ice Cores ◽  
Antimicrobial Effect ◽  
Uv Treatment ◽  
Melted Snow ◽  
Size Distribution Of Particles

<p>The storage of melted snow and/or ice samples from snow pits and ice cores in a refrigerator for long durations may be limited by an increase in particle concentration caused by microbial growth after approximately 1–2 weeks. In this study, we examined an ultraviolet (UV) disinfection method for the storage of melted snow and/or ice samples. Surface snow obtained from Glacier No. 31 in the Suntar-Khayata Range, eastern Siberia, Russia was divided into two portions for UV treatment and untreated controls. Particle concentrations in the samples were measured using a Coulter counter (Multisizer 4e; Beckman Coulter, USA). Whereas the particle concentration in untreated samples increased, no obvious increase was observed over 53 days in the samples subjected to UV treatment. In addition, the original particle concentrations were unaffected by UV treatment. These findings indicate that the antimicrobial effect of UV radiation is effective for long-term sample storage of melted water samples. A detailed analysis of the particle size distribution for untreated samples indicated that particles of 0.7–1.2 µm appeared within the first 7–14 days. Measurements using a viable particle counter (XL-10BT2 and XL-28A1; RION Co. Ltd., Japan) confirmed that these were biological particles, suggesting that microbial growth occurs during this period. Subsequently, the particles shifted to a smaller size and a higher concentration, suggesting that the decomposition of microorganisms occurred in the water samples. Therefore, the size distribution of particles in untreated samples reflected the growth and decomposition of microorganisms over time.</p>

scholarly journals Ultraviolet germicidal irradiation of melted snow and ice samples: inactivation of microorganisms and effects on insoluble microparticles

2021 ◽  
pp. 1-8
Author(s):  
Fumio Nakazawa ◽  
Kumiko Goto-Azuma
Keyword(s):  
Microbial Growth ◽  
Particle Concentration ◽  
Uv Disinfection ◽  
Size Distributions ◽  
Uv Treatment ◽  
Long Term Storage ◽  
Melted Snow ◽  
Term Storage ◽  
Biological Particle

Abstract The long-term refrigerated storage of melted snow and/or ice samples for analyses of insoluble microparticles (hereafter, microparticles) may be limited by increases in the biological particle concentration caused by microbial growth after ~1–2 weeks. In this study, we examined an ultraviolet (UV) disinfection method for the storage of melted snow and/or ice samples and determined the effects of this method on microparticles. Surface snow obtained from Glacier No. 31 in the Suntar-Khayata Range, eastern Siberia, Russia was divided into two portions for UV treatment and untreated controls. Microparticle concentrations and size distributions (in the range of 0.52–12.0 μm) in the samples were measured using a Coulter counter. Whereas the microparticle concentration in untreated samples increased, no obvious increase was observed over 53 d in the samples subjected to UV treatment. Microbial growth was detected in only untreated samples using a viable particle counter. In addition, the original microparticle concentrations and size distributions were unaffected by UV treatment. Our results demonstrated that the microparticle size distribution in untreated melted water samples reflects the growth, decomposition and succession of microorganisms over time and further indicate that UV irradiation is effective for long-term storage for microparticle analysis.

scholarly journals Long-term evolution of the heliospheric magnetic field inferred from cosmogenic 44Ti activity in meteorites

2018 ◽  
Vol 610 ◽  
pp. A28 ◽  
Author(s):  
S. Mancuso ◽  
C. Taricco ◽  
P. Colombetti ◽  
S. Rubinetti ◽  
N. Sinha ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Ice Cores ◽  
Long Term Evolution ◽  
Galactic Cosmic Rays ◽  
Sunspot Activity ◽  
Cosmogenic Isotopes ◽  
Heliospheric Magnetic Field ◽  
The Past ◽  
Term Evolution

Typical reconstructions of historic heliospheric magnetic field (HMF) BHMF are based on the analysis of the sunspot activity, geomagnetic data or on measurement of cosmogenic isotopes stored in terrestrial reservoirs like trees (14C) and ice cores (10Be). The various reconstructions of BHMF are however discordant both in strength and trend. Cosmogenic isotopes, which are produced by galactic cosmic rays impacting on meteoroids and whose production rate is modulated by the varying HMF convected outward by the solar wind, may offer an alternative tool for the investigation of the HMF in the past centuries. In this work, we aim to evaluate the long-term evolution of BHMF over a period covering the past twenty-two solar cycles by using measurements of the cosmogenic 44Ti activity (τ1∕2 = 59.2 ± 0.6 yr) measured in 20 meteorites which fell between 1766 and 2001. Within the given uncertainties, our result is compatible with a HMF increase from 4.87-0.30+0.24 nT in 1766 to 6.83-0.11+0.13 nT in 2001, thus implying an overall average increment of 1.96-0.35+0.43 nT over 235 years since 1766 reflecting the modern Grand maximum. The BHMF trend thus obtained is then compared with the most recent reconstructions of the near-Earth HMF strength based on geomagnetic, sunspot number, and cosmogenic isotope data.

scholarly journals In VitroEvaluation of the Antimicrobial Efficacy of Four Endodontic Biomaterials againstEnterococcus faecalis,Candida albicans, andStaphylococcus aureus

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Duddi Narendra Nirupama ◽  
Mohan Thomas Nainan ◽  
Rajendran Ramaswamy ◽  
Sethumadhavan Muralidharan ◽  
Hulimangala Hosakote Lingareddy Usha ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Direct Contact ◽  
Microbial Growth ◽  
Antimicrobial Property ◽  
Recurrent Infection ◽  
Antimicrobial Effect ◽  
Ah Plus ◽  
Endodontic Sealers ◽  
Root Canal Sealers ◽  
Direct Contact Test

Root canal sealers that possess good antimicrobial property can prevent residual and recurrent infection and contribute to successful endodontic therapy. This study evaluated the antimicrobial activity of four endodontic sealers, AH Plus, Tubliseal EWT, EndoRez, and iRoot SP, against three different microorganisms,E. faecalis, C. albicans, andS. aureus, by direct contact test. 10 μL microbial suspensions were allowed to directly contact the four endodontic sealers for 1 hr at 37°C. Subsequently microbial growth was measured spectrophotometrically every 30 min for 18 hours. The microbial suspensions were simultaneously tested to determine the antimicrobial effect of components which are capable of diffusing into the medium. The results revealed that AH Plus and iRootSP had significantly higher antimicrobial activity againstE. faecalis. AH Plus and Tubliseal EWT showed significantly higher antimicrobial activity againstC. albicansandS. aureuscompared to iRoot SP and EndoRez. EndoRez showed the least antimicrobial activity against all the three microorganisms. Inhibition of microbial growth is related to the direct contact of microorganisms with the sealers. In conclusion AH Plus had significantly higher antimicrobial activity againstE. faecalis, C. albicans, andS. aureus.

scholarly journals Multi-periodic climate dynamics: spectral analysis of long-term instrumental and proxy temperature records

2013 ◽  
Vol 9 (1) ◽  
pp. 447-452 ◽  
Author(s):  
H.-J. Lüdecke ◽  
A. Hempelmann ◽  
C. O. Weiss
Keyword(s):  
Pearson Correlation ◽  
Temperature Drop ◽  
Ice Cores ◽  
Climate Dynamics ◽  
Fluctuation Analysis ◽  
Harmonic Decomposition ◽  
The Mean ◽  
Temperature Records ◽  
Instrumental Records

Abstract. The longest six instrumental temperature records of monthly means reach back maximally to 1757 AD and were recorded in Europe. All six show a V-shape, with temperature drop in the 19th and rise in the 20th century. Proxy temperature time series of Antarctic ice cores show this same characteristic shape, indicating this pattern as a global phenomenon. We used the mean of the six instrumental records for analysis by discrete Fourier transform (DFT), wavelets, and the detrended fluctuation analysis (DFA). For comparison, a stalagmite record was also analyzed by DFT. The harmonic decomposition of the abovementioned mean shows only six significant frequencies above periods over 30 yr. The Pearson correlation between the mean, smoothed by a 15-yr running average (boxcar) and the reconstruction using the six significant frequencies, yields r = 0.961. This good agreement has a > 99.9% confidence level confirmed by Monte Carlo simulations. It shows that the climate dynamics is governed at present by periodic oscillations. We find indications that observed periodicities result from intrinsic dynamics.

scholarly journals Amplified bioproductivity during Transition IV (332 000–342 000 yr ago): evidence from the geochemical record of Lake El'gygytgyn

2013 ◽  
Vol 9 (2) ◽  
pp. 679-686 ◽  
Author(s):  
L. Cunningham ◽  
H. Vogel ◽  
V. Wennrich ◽  
O. Juschus ◽  
N. Nowaczyk ◽  
...  
Keyword(s):  
Sharp Increase ◽  
Biogenic Silica ◽  
Ice Cores ◽  
Climatic Conditions ◽  
The Arctic ◽  
Significant Shift ◽  
Geochemical Parameters ◽  
Lake El’Gygytgyn ◽  
Arctic Russia

Abstract. To date, terrestrial archives of long-term climatic change within the Arctic have widely been restricted to ice cores from Greenland and, more recently, sediments from Lake El'gygytgyn in northeast Arctic Russia. Sediments from this lake contain a paleoclimate record of glacial-interglacial cycles during the last three million years. Low-resolution studies at this lake have suggested that changes observed during Transition IV (the transition from marine isotope stage (MIS) 10 to MIS 9) are of greater amplitude than any observed since. In this study, geochemical parameters are used to infer past climatic conditions thus providing the first high-resolution analyses of Transition IV from a terrestrial Arctic setting. These results demonstrate that a significant shift in climate was subsequently followed by a rapid increase in biogenic silica (BSi) production. Following this sharp increase, bioproductivity remained high, but variable, for over a thousand years. This study reveals differences in the timing and magnitude of change within the ratio of silica to titanium (Si/Ti) and BSi records that would not be apparent in lower resolution studies. This has significant implications for the increasingly common use of Si/Ti data as an alternative to traditional BSi measurements.

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