scholarly journals Sarin and Air Permeation Through a Nanoporous Graphene

MRS Advances ◽  
2020 ◽  
Vol 5 (27-28) ◽  
pp. 1475-1482
Author(s):  
Marco A. Maria ◽  
Alexandre F. Fonseca
Keyword(s):  
Room Temperature ◽  
Initial Pressure ◽  
Chemical Warfare Agent ◽  
The Other ◽  
Graphene Nanosheet ◽  
Different Temperatures ◽  
Nanoporous Graphene ◽  
Dynamics Simulations ◽  
And Storage ◽  
Air Permeation

ABSTRACTSarin gas is a dangerous chemical warfare agent (CWA). It is a nerve agent capable of bringing a person to death in about 15 minutes. A lethal concentration of sarin molecules in air is about 30 mg/m3. Experimental research on this gas requires very careful safety protocols for handling and storage. Therefore, theoretical and computational studies on sarin gas are very welcome and might provide important safe guides towards the management of this lethal substance. In this work, we investigated the interactions between sarin, air and nanoporous graphene, using tools of classical molecular dynamics simulations. Aiming to cast some light in the possible sarin selective filtration by graphene, we designed a bipartite simulation box with a porous graphene nanosheet placed at the middle. Sarin and air molecules were initially placed only on one side of the box so as to create an initial pressure towards the passage of both to the other side. The box dimensions were chosen so that the hole in the graphene was the only possible way through which sarin and air molecules can get to the other side of the box. The number of molecules that passed through the hole in graphene was monitored during 10 ns of simulation and the results for different temperatures were compared. The results show that, as far as the size of the holes are small, van der Waals forces between graphene and the molecules play a significant role on keeping sarin near graphene, at room temperature.

scholarly journals Effects of Different Temperatures and Storage Time on the Degree of Conversion and Microhardness of Resin-based Composites

2016 ◽  
Vol 17 (3) ◽  
pp. 217-223 ◽  
Author(s):  
Maan M AlShaafi
Keyword(s):  
Room Temperature ◽  
Storage Time ◽  
Light Emitting Diode ◽  
Dental Materials ◽  
Degree Of Conversion ◽  
Curing Temperature ◽  
Significant Difference ◽  
Different Temperatures ◽  
And Storage ◽  
Made In

ABSTRACT Objective Dental materials are often made at room temperature, whereas clinically they are made in the mouth. This study evaluated the effects of temperature on the degree of conversion (DC) and Knoop microhardness (KHN). Materials and methods Two types of resin-based composites (RBCs) were light-cured using a light-emitting diode (LED) lightcuring unit. The resin specimens were centered on an Attenuated Total Reflectance Fourier transform infrared (FT-IR) plate heated to 23°C or 33°C. The DC of the resin was calculated after 120 seconds, the specimens were removed, and the KHN was tested at the bottom of the specimens both immediately, after 24 hours, and after 7 days storage in distilled water in complete darkness at 37°C. The effects of different temperatures on the DC and KHN with their storage time were compared by analysis of variance and Fisher's protected least significant difference post hoc multiple comparison tests (p < 0.05). Results Increasing the temperature had a significant and positive effect on the DC and KHN for immediate values of the RBCs. Greater conversion and hardness occurred when the curing temperature was increased from 23°C to 33°C. The KHN increased significantly after 24 hours of storage. There was a linear relationship between DC and KHN (R2 = 0.86) within the range of DC and KHN studied. Conclusion The physical properties of dental materials can be expected to be better when made in the mouth than when they are made in a laboratory at room temperature. How to cite this article AlShaafi MM. Effects of Different Temperatures and Storage Time on the Degree of Conversion and Microhardness of Resin-based Composites. J Contemp Dent Pract 2016;17(3):217-223.

MOLECULAR DYNAMICS STUDY OF THE COALESCENCE OF EQUAL AND UNEQUAL SIZED Cu NANOPARTICLES

2009 ◽  
Vol 20 (02) ◽  
pp. 179-196 ◽  
Author(s):  
H. H. KART ◽  
G. WANG ◽  
I. KARAMAN ◽  
T. ÇAĞIN
Keyword(s):  
Molecular Dynamics ◽  
Theoretical Calculations ◽  
The Other ◽  
Model Systems ◽  
Heat Of Fusion ◽  
Sintering Process ◽  
Melting Temperatures ◽  
Different Temperatures ◽  
Dynamics Simulations ◽  
Good Agreement

Molecular dynamics simulations technique is used to study the consolidation of two nanoparticles of Cu element. We have studied sintering processes of two nanoparticles at different temperatures. Two model systems with 4 and 10 nm diameter of particles are selected to study the sintering process of the two nanoparticles. Orientation effects on the physical properties of consolidation of two nanoparticles with respect to each other are investigated. Temperature effects on the consolidation of two nanoparticles are also studied. The order of the values obtained in the simulation for the constant volume heat capacity and latent heat of fusion is good agreement with the bulk results. Moreover, we have investigated the size effects on the consolidation of two different sizes of nanoparticles, that is, one particle of diameter with 10 nm is fixed while the other one is changing from 1 to 10 nm. Melting temperatures of the copper nanoparticles are found to be decreased as the size of the particle decreases. It is found that simulation results are compatible with the other theoretical calculations.

PD Fluids Contain High Concentrations of Cytotoxic GDPs Directly after Sterilization

2004 ◽  
Vol 24 (4) ◽  
pp. 392-398 ◽  
Author(s):  
Martin Erixon ◽  
Torbjörn Lindén ◽  
Per Kjellstrand ◽  
Ola Carlsson ◽  
Malin Ernebrant ◽  
...  
Keyword(s):  
Peritoneal Dialysis ◽  
Main Part ◽  
Room Temperature ◽  
Degradation Products ◽  
The Other ◽  
Dependent Manner ◽  
Peritoneal Membrane ◽  
Temperature Dependent ◽  
Different Temperatures ◽  
High Concentrations

Objective Glucose degradation products (GDPs) in peritoneal dialysis (PD) fluids are cytotoxic and affect the survival of the peritoneal membrane. One of the most reactive GDPs in PD fluids is 3,4-dideoxyglucosone-3-ene (3,4-DGE). 3,4-DGE has been reported as an intermediate between 3-deoxyglucosone (3-DG) and 5-hydroxymethyl furaldehyde (5-HMF) during degradation of glucose. In PD fluids, 3,4-DGE exists in a temperature-dependent equilibrium with a pool of unidentified substances. The aim of this study was to explore this equilibrium and its temperature dependence during the first months of storage after the sterilization procedure. Methods GDPs and inhibition of cell growth (ICG) were measured directly after sterilization of the PD fluid and during storage at different temperatures for 60 days. The following GDPs were analyzed: 3-DG, 3,4-DGE, 5-HMF, formaldehyde, acetaldehyde, glyoxal, and methylglyoxal. Results Immediately after sterilization, the concentration of 3,4-DGE was 125 μmol/L. During the first weeks of storage, it decreased by about 80%. At the same time, the 3-DG concentration increased. None of the other GDPs were significantly affected. Cytotoxicity correlated well with the concentration of 3,4-DGE. When pure 3,4-DGE was substituted for the lost amount of 3,4-DGE after 30 days of storage, the initial ICG was almost completely regained. Conclusions Heat sterilization of PD fluids promotes the formation of large quantities of 3,4-DGE, rendering the fluid highly cytotoxic. During storage, the main part of 3,4-DGE is reversibly converted in a temperature-dependent manner to a less cytotoxic pool, consisting mainly of 3-DG. Cytotoxicity seems to be dependent exclusively on 3,4-DGE. In order to avoid higher levels of 3,4-DGE concentrations, PD fluids should not be used too soon after sterilization and should not be stored at temperatures above room temperature.

scholarly journals Evaluation of sample preservation and storage methods for metaproteomics analysis of intestinal microbiomes

2021 ◽  
Author(s):  
Angie Mordant ◽  
Manuel Kleiner
Keyword(s):  
Gene Expression ◽  
Liquid Nitrogen ◽  
Room Temperature ◽  
The Other ◽  
Intestinal Microbiome ◽  
Protein Abundance ◽  
Fecal Microbiome ◽  
Storage Methods ◽  
And Storage ◽  
Measure Gene Expression

A critical step in studies of the intestinal microbiome using meta-omics approaches is the preservation of samples before analysis. Preservation is essential for approaches that measure gene expression, such as metaproteomics, which is used to identify and quantify proteins in microbiomes. Intestinal microbiome samples are typically stored by flash freezing and storage at -80 oC, but some experimental set-ups do not allow for immediate freezing of samples. In this study, we evaluated methods to preserve fecal microbiome samples for metaproteomics analyses when flash freezing is not possible. We collected fecal samples from C57BL/6 mice and stored them for 1 and 4 weeks using the following methods: flash-freezing in liquid nitrogen, immersion in RNAlater™, immersion in 95% ethanol, immersion in a RNAlater-like buffer, and combinations of these methods. After storage we extracted protein and prepared peptides for LC-MS/MS analysis to identify and quantify peptides and proteins. All samples produced highly similar metaproteomes, except for ethanol-preserved samples that were distinct from all other samples in terms of protein identifications and protein abundance profiles. Flash-freezing and RNAlater™ (or RNAlater-like treatments) produced metaproteomes that differed only slightly, with less than 0.7% of identified proteins differing in abundance. In contrast, ethanol preservation resulted in an average of 9.5% of the identified proteins differing in abundance between ethanol and the other treatments. Our results suggest that preservation at room temperature in RNAlater™,or an RNAlater-like solution, performs as well as freezing for the preservation of intestinal microbiome samples before metaproteomics analyses.

scholarly journals Stability of lactoferrin and lysozyme in human milk at various temperatures and duration of storage

2021 ◽  
Vol 27 (2) ◽  
Author(s):  
◽  
Sumirah Budi Pertami ◽  
Agus Setyo Utomo ◽  
Siti Nur Arifah ◽  
◽  
...  
Keyword(s):  
Human Milk ◽  
Room Temperature ◽  
Storage Time ◽  
Enzyme Linked Immunosorbent Assay ◽  
Milk Samples ◽  
Duration Of Storage ◽  
Different Temperatures ◽  
Bioactive Content ◽  
The Stability ◽  
And Storage

Introduction: Exclusive breastfeeding, especially in the first six months, is essential for infants as it provides nutrition and protection against various diseases. Colostrum, which is found in the first breast milk produced, contains various protective factors, such as lactoferrin and lysozyme. Human milk can be stored at room temperature, refrigerated, or kept frozen. Several factors affect the stability of the bioactive content in human milk, such as temperature and storage time. The aim of this study was to measure the stability of lactoferrin and lysozyme levels in human milk during the first six hours (h) at different temperatures and compare it with that of frozen human milk. Methods: Human milk samples were obtained from 11 breastfeeding mothers using certain criteria. The human milk was stored at room temperature and 4°C for 1, 3, and 6 h and classified as never frozen, while frozen human milk was stored at -20°C for 1, 3, and 6 days. Measurement of the lactoferrin and lysozyme levels was performed using enzyme-linked immunosorbent assay. Results: The results showed that storage at room temperature significantly reduced lactoferrin and lysozyme levels. Lactoferrin levels in frozen human milk did not significantly decrease during the first six days. Meanwhile, the lysozyme levels in frozen human milk decreased significantly. Conclusion: The levels of lactoferrin and lysozyme in frozen human milk stored for the first six days were more stable than those stored at room temperature and 4°C in the first 6 h.

The Influence of Texture and Firing on Thermal and Elastic Properties of Illite-Based Ceramics

2015 ◽  
Vol 1126 ◽  
pp. 53-58 ◽  
Author(s):  
Daniel Antal ◽  
Tomáš Húlan ◽  
Anton Trník ◽  
Igor Štubňa ◽  
Ján Ondruška
Keyword(s):  
Thermal Diffusivity ◽  
Heating Rate ◽  
Elastic Properties ◽  
Room Temperature ◽  
Young Modulus ◽  
Thin Layers ◽  
The Other ◽  
Relative Dimension ◽  
Plastic Mass ◽  
Different Temperatures

The texture in illite-based ceramics was introduced by spreading a large number of thin layers of a wet plastic mass one on top of the other. The basal planes of the plate-like illite crystals are predominantly oriented parallely with the direction of spreading. The samples were fired at different temperatures ranging from room temperature up to 1100 °C with a heating rate of 5 °C/min, then freely cooled and measured at room temperature. We determined Young modulus (E), thermal diffusivity (a) and relative dimension changes (Δl/l0) in two directions: parallely to the basal planes (a subscript ||) of the illite crystals and perpendicularly to these planes (a subscript ⊥). It was found that the ratio E|| / E⊥ ≈ 2.9 and a|| / a⊥ ≈ 2.0 up to 900 °C. Above 900 °C, the values of E and a increase due to sintering, and the differences between the values measured in the two directions decrease. In the case of the thermal diffusivity these differences do not disappear even after firing at the temperature of 1200 °C.

scholarly journals Effects of Pretreatments on the Shelf Life and Quality of Carrots (Daucus carota Subspecies Sativus) Stored at Different Temperatures

2019 ◽  
pp. 1-8
Author(s):  
Omolara Ojuolape Adeoye ◽  
Tinuola Tokunbo Adebolu ◽  
Muftau Kolawole Oladunmoye ◽  
Anthony O. Ojokoh
Keyword(s):  
Shelf Life ◽  
Aqueous Extract ◽  
Room Temperature ◽  
Potable Water ◽  
Soft Rot ◽  
The Other ◽  
The World ◽  
Different Temperatures ◽  
Ondo State

Carrot is one of the top ten most important vegetables in the world due to its nutritional contents however, it is highly perishable. One major way to extend its shelf life is to store in the refrigerator but these can only prolong the shelf life for only a few weeks. Therefore, there is the need to research how the shelf life can be extended further. Fresh matured carrots bought from Shasha market in Akure, Ondo State, Nigeria were washed with potable water and grouped into 7; each group was subjected to different pretreatment except the 7th group that was left untreated. All the carrot groups were dried in sun for five hours and then packed aseptically into different sterile air tight polyethylene food bags. Each group was replicated and one batch was stored in the refrigerator (4 ± 2°C) while the other batch was stored at room temperature (30 ± 2°C).  At intervals of one week, the samples were monitored for presence of soft rot, wrinkle, weight loss etc.  All carrots stored at 30 ± 2°C got spoiled after first week of storage irrespective of the type of pretreatment they were subjected to. However, pretreated carrots stored at 4 ± 2°C had their shelf life extended with those treated with moringa seed aqueous extract having the best result at 24th week. This work shows that moringa seed aqueous extract can be used to extend the shelf life of carrots stored in the refrigerator.

Electron microscope studies of the plastic deformation of ternary alloys based on GaAs

1990 ◽  
Vol 48 (4) ◽  
pp. 1120-1120
Author(s):  
R. Haswell ◽  
U. Bangert ◽  
P. Charsley
Keyword(s):  
Plastic Deformation ◽  
Electron Microscope ◽  
Room Temperature ◽  
Stacking Faults ◽  
The Other ◽  
Ternary Alloys ◽  
Dislocation Mobility ◽  
Semiconducting Materials ◽  
Micro Indentation

A knowledge of the behaviour of dislocations in semiconducting materials is essential to the understanding of devices which use them . This work is concerned with dislocations in alloys related to the semiconductor GaAs . Previous work on GaAs has shown that microtwinning occurs on one of the <110> rosette arms after indentation in preference to the other . We have shown that the effect of replacing some of the Ga atoms by Al results in microtwinning in both of the rosette arms.In the work to be reported dislocations in specimens of different compositions of Gax Al(1-x) As and Gax In(1-x) As have been studied by using micro indentation on a (001) face at room temperature . A range of electron microscope techniques have been used to investigate the type of dislocations and stacking faults/microtwins in the rosette arms , which are parallel to the [110] and [10] , as a function of composition for both alloys . Under certain conditions microtwinning occurs in both directions . This will be discussed in terms of the dislocation mobility.

Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

1977 ◽  
Vol 16 (01) ◽  
pp. 30-35 ◽  
Author(s):  
N. Agha ◽  
R. B. R. Persson
Keyword(s):  
Complex Formation ◽  
Significant Influence ◽  
Room Temperature ◽  
Ph Value ◽  
Maximum Activity ◽  
Reduction Step ◽  
Labelling Yield ◽  
Different Temperatures ◽  
Kinetics Of

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).

Investigations on the Nature of Hemophilia A

1963 ◽  
Vol 09 (01) ◽  
pp. 030-052 ◽  
Author(s):  
Eberhard Mammen
Keyword(s):  
Factor Viii ◽  
Human Plasma ◽  
Barium Sulfate ◽  
Freeze Drying ◽  
Room Temperature ◽  
Hemophilia A ◽  
Normal Human Plasma ◽  
Normal Human ◽  
And Storage ◽  
Prothrombin Activation

SummaryIn this paper an inhibitor is described that is found in hemophilic plasma and serum different from any till now described inhibitor. The inhibitor only inhibits prothrombin activation in the “intrinsic clotting systems”. This inhibitor is probably not present in normal human plasma or serum. It is destroyed by ether and freeze drying, is labile to acid and storage at room temperature. It is stable upon dialysis and has not been adsorbed on barium sulfate, aluminum hydroxide or kaolin. It precipitates at 50% v/v saturation with alcohol. The nature of this inhibitor seems to be a protein or lipoprotein.Factor VIII was isolated from hemophilic plasma. The amount isolated was the same as from normal plasma and the activity properties were not different. Hemophiliacs have normal amounts of factor VIII.

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