scholarly journals The Dynamics of SARS-CoV-2 Infectivity with Changes in Aerosol Microenvironment

2022 ◽  
Author(s):  
Henry Oswin ◽  
Allen Haddrell ◽  
Mara Otero-Fernandez ◽  
Jamie Mann ◽  
Tristan Cogan ◽  
...  
Keyword(s):  
Initial Rate ◽  
Physicochemical Analysis ◽  
Small Population ◽  
Mitigation Strategies ◽  
Similar Degree ◽  
Bicarbonate Buffer ◽  
Physical Transformation ◽  
The Stability

Understanding the factors that influence the airborne survival of viruses such as SARSCoV2 in aerosols is important for identifying routes of transmission and the value of various mitigation strategies for preventing transmission. We present measurements of the stability of SARSCoV2 in aerosol droplets (5 to 10 micrometres equilibrated radius) over timescales spanning from 5 seconds to 20 minutes using a novel instrument to probe survival in a small population of droplets (typically 5-10) containing ~1 virus/droplet. Measurements of airborne infectivity change are coupled with a detailed physicochemical analysis of the airborne droplets containing the virus. A decrease in infectivity to 10 % of the starting value was observable for SARS-CoV-2 over 20 minutes, with a large proportion of the loss occurring within the first 5 minutes after aerosolisation. The initial rate of infectivity loss was found to correlate with physical transformation of the equilibrating droplet; salts within the droplets crystallise at RHs below 50% leading to a near instant loss of infectivity in 50 to 60% of the virus. However, at 90% RH the droplet remains homogenous and aqueous, and the viral stability is sustained for the first 2 minutes, beyond which it decays to only 10% remaining infectious after 10 minutes. The loss of infectivity at high RH is consistent with an elevation in the pH of the droplets, caused by volatilisation of CO2 from bicarbonate buffer within the droplet. Three different variants of SARS-CoV-2 were compared and found to have a similar degree of airborne stability at both high and low RH.

scholarly journals Stabilizing electrodeposition in elastic solid electrolytes containing immobilized anions

2016 ◽  
Vol 2 (7) ◽  
pp. e1600320 ◽  
Author(s):  
Mukul D. Tikekar ◽  
Lynden A. Archer ◽  
Donald L. Koch
Keyword(s):  
Elastic Solid ◽  
Present Theory ◽  
Metal Electrode ◽  
Mitigation Strategies ◽  
Factors Affecting ◽  
Wide Range ◽  
Current Densities ◽  
Morphological Instabilities ◽  
The Stability

Ion transport–driven instabilities in electrodeposition of metals that lead to morphological instabilities and dendrites are receiving renewed attention because mitigation strategies are needed for improving rechargeability and safety of lithium batteries. The growth rate of these morphological instabilities can be slowed by immobilizing a fraction of anions within the electrolyte to reduce the electric field at the metal electrode. We analyze the role of elastic deformation of the solid electrolyte with immobilized anions and present theory combining the roles of separator elasticity and modified transport to evaluate the factors affecting the stability of planar deposition over a wide range of current densities. We find that stable electrodeposition can be easily achieved even at relatively high current densities in electrolytes/separators with moderate polymer-like mechanical moduli, provided a small fraction of anions are immobilized in the separator.

scholarly journals Failure Mechanism and Mitigation Measures of the G1002 Electricity Pylon Landslide at the Jinping I Hydropower Station

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Gang Luo ◽  
Yutian Zhong ◽  
Yuanxiang Yang
Keyword(s):  
Failure Mechanism ◽  
Power Transmission ◽  
Heavy Precipitation ◽  
Mitigation Strategies ◽  
Mitigation Measures ◽  
Hydropower Station ◽  
Residual Soil ◽  
Valley Slope ◽  
Jinping I Hydropower Station ◽  
The Stability

On August 29 and 30, 2012, local extreme rainfalls struck the construction area of the Jinping I Hydropower Station, Xichang, China, and triggered many geohazards. The upper region of the left valley slope 200 m downstream of the dam failed and slid, exposing the D-pile of the G1002 electricity pylon and threatening the entire power transmission line. Therefore, guaranteeing the stability of the residual soil masses in the rear area of the main scarp and the safety of the G1002 electricity pylon became a primary emergency task. Geological field surveys, topographical mapping, study of the failure mechanisms, and stability evaluations were carried out from October 12, 2012, to November 7, 2013. It is revealed that the failure mechanism of the G1002 electricity pylon landslide is flood-induced tractive sliding along the interlayer between the colluvium and the bedrock, significantly influenced by heavy precipitation and frequent blasting activities during the dam construction. The residual soil masses around the G1002 electricity pylon foundation are unstable under rainfall conditions. In order to ensure the stability of the residual soil masses and pylon foundation, a mitigation measure of the anchor cables combined with lattice frame beams was proposed and applied in practice. This paper provides insights into the problems associated with the selection of the locations of electricity pylons in ravine regions as well as mitigation strategies for similar landslides.

scholarly journals Increasing Temperature and Relative Humidity Accelerates Inactivation of SARS-CoV-2 on Surfaces

mSphere ◽  
2020 ◽  
Vol 5 (4) ◽  
Author(s):  
Jennifer Biryukov ◽  
Jeremy A. Boydston ◽  
Rebecca A. Dunning ◽  
John J. Yeager ◽  
Stewart Wood ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Culture Media ◽  
Mitigation Strategies ◽  
Accurate Estimation ◽  
Clinical Settings ◽  
Indoor Environments ◽  
Type Stainless Steel ◽  
Contact Transmission ◽  
The Stability ◽  
Increasing Temperature

ABSTRACT Coronavirus disease 2019 (COVID-19) was first identified in China in late 2019 and is caused by newly identified severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Previous studies had reported the stability of SARS-CoV-2 in cell culture media and deposited onto surfaces under a limited set of environmental conditions. Here, we broadly investigated the effects of relative humidity, temperature, and droplet size on the stability of SARS-CoV-2 in a simulated clinically relevant matrix dried on nonporous surfaces. The results show that SARS-CoV-2 decayed more rapidly when either humidity or temperature was increased but that droplet volume (1 to 50 μl) and surface type (stainless steel, plastic, or nitrile glove) did not significantly impact decay rate. At room temperature (24°C), virus half-life ranged from 6.3 to 18.6 h depending on the relative humidity but was reduced to 1.0 to 8.9 h when the temperature was increased to 35°C. These findings suggest that a potential for fomite transmission may persist for hours to days in indoor environments and have implications for assessment of the risk posed by surface contamination in indoor environments. IMPORTANCE Mitigating the transmission of SARS-CoV-2 in clinical settings and public spaces is critically important to reduce the number of COVID-19 cases while effective vaccines and therapeutics are under development. SARS-CoV-2 transmission is thought to primarily occur through direct person-to-person transfer of infectious respiratory droplets or through aerosol-generating medical procedures. However, contact with contaminated surfaces may also play a significant role. In this context, understanding the factors contributing to SARS-CoV-2 persistence on surfaces will enable a more accurate estimation of the risk of contact transmission and inform mitigation strategies. To this end, we have developed a simple mathematical model that can be used to estimate virus decay on nonporous surfaces under a range of conditions and which may be utilized operationally to identify indoor environments in which the virus is most persistent.

scholarly journals MOISTURE AND ACIDITY AS INDICATORS OF THE QUALITY OF HONEY ORIGINATING FROM VOJVODINA REGION

2015 ◽  
Vol 7 (2) ◽  
pp. 99-109 ◽  
Author(s):  
Nadežda Prica ◽  
Milica Živkov Baloš ◽  
Sandra Jakšić ◽  
Željko Mihaljev ◽  
Brankica Kartalović ◽  
...  
Keyword(s):  
Moisture Content ◽  
Storage Conditions ◽  
Physicochemical Analysis ◽  
Yeast Fermentation ◽  
The Stability ◽  
Processing And Storage ◽  
And Storage ◽  
Alcohol Formation ◽  
Positive Quality

The color, aroma and fl avor are major sensory characteristics of honey, which are mainly determined by the botanical origin of honey as well as by processing and storage conditions. Increased moisture content above the maximum permitted level could result in honey spoilage, which aff ects its sensory properties. The higher water-in-honey content, the greater possibility of yeast fermentation and thus the change of the fl avor and color ofhoney. Fermentation process results in alcohol formation and, in the presence of oxygen, the alcohol will break down to acetic acid and water, which causes honey to have sour taste. Thus, moisture content of honey is a critical parameter for its quality as it aff ects the stability of honey and its resistance to microbial spoilage during storage. Physicochemical analysis of moisture content and acidity of honey play an important role in determining the overall characteristic of honey and final assessment of its quality. In this study, the investigation of aforementioned parameters resulted in positive quality assessment for 48 of 50 examined honey samples produced in 2013 in the territory of Vojvodina.

The stability of uric acid in ammonium hydroxide.

1988 ◽  
Vol 34 (11) ◽  
pp. 2280-2282 ◽  
Author(s):  
P Ellerbe ◽  
A Cohen ◽  
M J Welch ◽  
E White
Keyword(s):  
Mass Spectrometry ◽  
Uric Acid ◽  
Initial Rate ◽  
Ammonium Hydroxide ◽  
Ammonium Hydroxide Solution ◽  
Hydroxide Solution ◽  
The Stability ◽  
Decomposition Curve

Abstract We examined the stability of uric acid in dilute aqueous ammonium hydroxide solution by mass spectrometry. Uric acid decomposes in ammonium hydroxide even as dilute as 15 mmol/L when the mole ratio of ammonium hydroxide to uric acid is 50:1. There are at least four products of the decomposition, two of which have been identified as allantoin and urea. The slope of the decomposition curve indicates that uric acid is destroyed at an initial rate of 2-3% per hour. In ammonium hydroxide at a concentration of 1 mmol/L and a mole ratio of ammonium hydroxide to uric acid of less than or equal to 3.4, uric acid is not detectably decomposed. Evidently, any method for determination of uric acid that involves treating the analyte with ammonium hydroxide before analysis may destroy it. Therefore, a published method described as being "definitive" for uric acid (J Clin Chem Clin Biochem 1985; 23:129-35) could produce incorrect results because it involves storing the uric acid in 15 mmol/L ammonium hydroxide at a mole ratio of ammonium hydroxide to uric acid of greater than 120:1.

scholarly journals Mechanistic theory predicts the effects of temperature and humidity on inactivation of SARS-CoV-2 and other enveloped viruses

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Dylan H Morris ◽  
Kwe Claude Yinda ◽  
Amandine Gamble ◽  
Fernando W Rossine ◽  
Qishen Huang ◽  
...  
Keyword(s):  
Mechanistic Model ◽  
Virus Transmission ◽  
Mitigation Strategies ◽  
Transmission Risk ◽  
Mechanistic Study ◽  
Enveloped Viruses ◽  
Temperature And Humidity ◽  
Inert Surface ◽  
Human Coronaviruses ◽  
The Stability

Ambient temperature and humidity strongly affect inactivation rates of enveloped viruses, but a mechanistic, quantitative theory of these effects has been elusive. We measure the stability of SARS-CoV-2 on an inert surface at nine temperature and humidity conditions and develop a mechanistic model to explain and predict how temperature and humidity alter virus inactivation. We find SARS-CoV-2 survives longest at low temperatures and extreme relative humidities (RH); median estimated virus half-life is >24 hours at 10C and 40% RH, but ~1.5 hours at 27C and 65% RH. Our mechanistic model uses fundamental chemistry to explain why inactivation rate increases with increased temperature and shows a U-shaped dependence on RH. The model accurately predicts existing measurements of five different human coronaviruses, suggesting that shared mechanisms may affect stability for many viruses. The results indicate scenarios of high transmission risk, point to mitigation strategies, and advance the mechanistic study of virus transmission.

Gain and loss of resistance in the fungus Penicillium roqueforti Thom

1959 ◽  
Vol 150 (938) ◽  
pp. 120-130 ◽  
Keyword(s):  
Sodium Azide ◽  
Acquired Resistance ◽  
Small Population ◽  
Similar Process ◽  
Penicillium Roqueforti ◽  
Phenylmercuric Acetate ◽  
Loss Of Resistance ◽  
Stability Of Resistance ◽  
High Concentrations ◽  
The Stability

Penicillium roqueforti Thom. readily acquires resistance to high concentrations of phenylmercuric acetate, proflavine, brilliant green, and sodium azide. Resistance is acquired gradually, and no evidence of mutation associated with this resistance could be detected. The stability of resistance to most drugs studied is low, and the organism rapidly returns to the sensitive state when grown in drug-free medium. In the case of resistance to phenylmercuric acetate, this loss of resistance occurred more or less simultaneously in all spores of a small population. Loss of resistance to other drugs seemed to occur simultaneously in at least a high proportion of spores. Strains which had been subcultured for a number of times on high concentrations of phenylmercuric acetate retained the resistance rather longer. Loss of resistance to proflavine was not complete, but the level of acquired resistance dropped slowly to a new intermediate level, well above the level of sensitive strains. Strains which had acquired resistance to sodium azide showed slight reluctance in giving up this resistance, but eventually returned to the sensitive state. The general parallelism between the phenomena of resistance in this fungus and in bacteria and yeasts leads to the conclusion that a similar process is operative in the three forms of micro-organisms. The low stability of acquired resistance would, according to a mutation theory, demand a mutation rate which seems improbably high.

scholarly journals Solvates and polymorphs of rebamipide: preparation, characterization, and physicochemical analysis

RSC Advances ◽  
2017 ◽  
Vol 7 (38) ◽  
pp. 23279-23286 ◽  
Author(s):  
Xinnuo Xiong ◽  
Qiaohong Du ◽  
Xia Zeng ◽  
Jiawei He ◽  
Hongqin Yang ◽  
...  
Keyword(s):  
Dissolution Rate ◽  
Physicochemical Analysis ◽  
The Stability

Preparation and characterization of four solvates and three novel polymorphs of rebamipide, and investigations on the stability, solubility, and dissolution rate of the stable solid forms.

scholarly journals The degradation of semisynthetic tritiated insulin by perfused mouse livers

1976 ◽  
Vol 160 (2) ◽  
pp. 409-412 ◽  
Author(s):  
P A Halban ◽  
C Karakash ◽  
J G Davies ◽  
R E Offord
Keyword(s):  
Linear Function ◽  
Initial Rate ◽  
Degradation Products ◽  
Native Insulin ◽  
The Stability

Semisynthetic [3H]insulin was stored under various conditions for up to 180 days and the stability of the insulin under these conditions was assessed. A sample that had been stored for 180 days was repurified and shown to be degraded at the same rate as native insulin by perfused mouse livers, even at low physiological concentrations. After perfusion, intact insulin could be separated from degradation products, and the radioactivity associated with the insulin fraction could be used to determine the percentage degradation. The initial rate of degradation of insulin was a linear function of concentration over the range 360pM-1.9nM.

scholarly journals Extraction and Physicochemical Characterization of Oil from Unripe Plantain (Musa Paradisiaca) Peels

2020 ◽  
pp. 151-155
Author(s):  
Orodu Victor Enearepuadoh ◽  
Igara Evawere Abigail
Keyword(s):  
Physicochemical Properties ◽  
Physicochemical Characterization ◽  
Iodine Content ◽  
Acid Value ◽  
Physicochemical Analysis ◽  
Human Consumption ◽  
Musa Paradisiaca ◽  
The Mean ◽  
The Stability

Extraction and physicochemical analysis of oil from unripe plantain (Musa paradisiaca) peels was carried out using cold extraction method. The peels were washed with distilled water, sun dried for 3 hours and oven dried for 6 hours at 85oC. It was then ground thoroughly. 700g of the sample was weighed and 1.20 liter of n-hexane was added for 72 hours. It was placed in a water bath for the evaporation of the solvent. The physicochemical properties determined were Saponification Value (SV), Iodine Value (IV), Free Fatty Acid Value (FFA), Peroxide Value (PV), Acid Value (AV) the mean results obtained SV 335.18mg/KOH/g, IV 7.16gI2/100g, FFA 338.76mg/KOH/g, AV 696.35mg/KOH/g and PV 328.46meq/kg. In comparing these physicochemical properties with the standard given by WHO/FAO, it was observed that IV and PV were below the range, SV, AV and FFA was above the range. Hence, the oil obtained from unripe plantain (Musa paradisiaca) peels is not fit for human consumption because AV, SV and FFA are higher than the standard given by WHO/FAO rather it can be used for making of soap and shampoos, PV showed the stability of the oil and IV indicates it’s nondrying quality which will not be suitable for ink and paint making due to its low iodine content.

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