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https://www.readbyqxmd.com/read/28328022/modifications-to-the-azide-method-for-nitrate-isotope-analysis
#1
Ying Tu, Yunting Fang, Dongwei Liu, Yuepeng Pan
RATIONALE: The azide method for measuring the stable isotope ratios of nitrate (NO3(-) ) is easy to set up. However, the method requires spongy cadmium (Cd) or activated Cd powder which are not easy to prepare, and a toxic azide buffer is used. We aimed to use Cd powder directly to simplify preparation and to substantially reduce the azide dose. METHODS: The reaction conditions were optimized in order to maximize the NO3(-) reduction yield. The original azide buffer was diluted by 10- to 10000-fold with or without addition of sodium acetate to reduce O-exchange between nitrite (NO2(-) ) and H2 O...
May 30, 2016: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/28326759/a-practical-cryogen-free-co2-purification-and-freezing-technique-for-stable-isotope-analysis
#2
Saburo Sakai, Shinichi Matsuda
 Since isotopic analysis by mass spectrometer began in the early 1900s, sample gas for light-element isotopic measurement has been purified by the use of cryogens and vacuum-line systems. However, this conventional purification technique can achieve only certain temperatures, which depend on the cryogens, and can be sustained only as long as there is a continuous cryogen supply. Here, we demonstrate a practical cryogen-free CO2 purification technique using an electrical operated cryocooler for stable isotope analysis...
March 22, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28326729/-study-of-human-leucine-rich-amelogenin-peptide-and-its-regulation-of-mineralization-by-cryogenic-transmission-electron-microscopy
#3
Tian Kun, Feng Xiaoyun, Du Qin, Liao Chuhang, Ren Xiaohua
OBJECTIVE: Recombinant human leucine-rich amelogenin peptide (LRAP) was studied by cryogenic transmission electron microscopy (TEM); evaluation focused on its self-assembly and crystal growth in vitro. METHODS: Human LRAP was recombined through prokaryotic expression vector pCold-SUMO and transformed into Escherichia coli BL21plys to acquire purified proteins. Cryogen TEM recorded assembly and self-assembling of LRAP from pH 3.5 to pH 8.0, and the hydroxyapatite crystal growth in the mixture of LRAP protein solution and artificial saliva was observed using TEM and selected area electron diffraction...
February 1, 2017: Hua Xi Kou Qiang Yi Xue za Zhi, Huaxi Kouqiang Yixue Zazhi, West China Journal of Stomatology
https://www.readbyqxmd.com/read/28322324/high-temperature-near-field-nanothermomechanical-rectification
#4
Mahmoud Elzouka, Sidy Ndao
Limited performance and reliability of electronic devices at extreme temperatures, intensive electromagnetic fields, and radiation found in space exploration missions (i.e., Venus &Jupiter planetary exploration, and heliophysics missions) and earth-based applications requires the development of alternative computing technologies. In the pursuit of alternative technologies, research efforts have looked into developing thermal memory and logic devices that use heat instead of electricity to perform computations...
March 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28317332/high-throughput-gas-chromatography-for-volatile-compounds-analysis-by-fast-temperature-programming-and-adsorption-chromatography
#5
Ronda Gras, Yujuan Hua, Jim Luong
The synergy of combining fast temperature programming capability and adsorption chromatography using fused silica based porous layer open tubular columns to achieve high throughput chromatography for the separation of volatile compounds is presented.A gas chromatograph with built-in fast temperature programming capability and having a fast cool down rate was used as a platform. When these performance features were combined with the high degree of selectivity and strong retention characteristic of porous layer open tubular column technology, volatile compounds such as light hydrocarbons of up to C7 , primary alcohols, and mercaptans can be well separated and analyzed in a matter of minutes...
March 20, 2017: Journal of Separation Science
https://www.readbyqxmd.com/read/28314413/recent-progress-in-the-discovery-and-development-of-trpa1-modulators
#6
S Skerratt
TRPA1 is a well-validated therapeutic target in areas of high unmet medical need that include pain and respiratory disorders. The human genetic rationale for TRPA1 as a pain target is provided by a study describing a rare gain-of-function mutation in TRPA1, causing familial episodic pain syndrome. There is a growing interest in the TRPA1 field, with many pharmaceutical companies reporting the discovery of TRPA1 chemical matter; however, GRC 17536 remains to date the only TRPA1 antagonist to have completed Phase IIa studies...
2017: Progress in Medicinal Chemistry
https://www.readbyqxmd.com/read/28306316/first-measurements-of-deuterium-tritium-and-deuterium-deuterium-fusion-reaction-yields-in-ignition-scalable-direct-drive-implosions
#7
C J Forrest, P B Radha, J P Knauer, V Yu Glebov, V N Goncharov, S P Regan, M J Rosenberg, T C Sangster, W T Shmayda, C Stoeckl, M Gatu Johnson
The deuterium-tritium (D-T) and deuterium-deuterium neutron yield ratio in cryogenic inertial confinement fusion (ICF) experiments is used to examine multifluid effects, traditionally not included in ICF modeling. This ratio has been measured for ignition-scalable direct-drive cryogenic DT implosions at the Omega Laser Facility [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)OPCOB80030-401810.1016/S0030-4018(96)00325-2] using a high-dynamic-range neutron time-of-flight spectrometer. The experimentally inferred yield ratio is consistent with both the calculated values of the nuclear reaction rates and the measured preshot target-fuel composition...
March 3, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28303107/localization-and-ordering-of-lipids-around-aquaporin-0-protein-and-lipid-mobility-effects
#8
Rodolfo Briones, Camilo Aponte-Santamaría, Bert L de Groot
Hydrophobic matching, lipid sorting, and protein oligomerization are key principles by which lipids and proteins organize in biological membranes. The Aquaporin-0 channel (AQP0), solved by electron crystallography (EC) at cryogenic temperatures, is one of the few protein-lipid complexes of which the structure is available in atomic detail. EC and room-temperature molecular dynamics (MD) of dimyristoylglycerophosphocholine (DMPC) annular lipids around AQP0 show similarities, however, crystal-packing and temperature might affect the protein surface or the lipids distribution...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28302855/direct-observation-of-individual-hydrogen-atoms-at-trapping-sites-in-a-ferritic-steel
#9
Y-S Chen, D Haley, S S A Gerstl, A J London, F Sweeney, R A Wepf, W M Rainforth, P A J Bagot, M P Moody
The design of atomic-scale microstructural traps to limit the diffusion of hydrogen is one key strategy in the development of hydrogen-embrittlement-resistant materials. In the case of bearing steels, an effective trapping mechanism may be the incorporation of finely dispersed V-Mo-Nb carbides in a ferrite matrix. First, we charged a ferritic steel with deuterium by means of electrolytic loading to achieve a high hydrogen concentration. We then immobilized it in the microstructure with a cryogenic transfer protocol before atom probe tomography (APT) analysis...
March 17, 2017: Science
https://www.readbyqxmd.com/read/28299942/temperature-dependent-electric-field-poling-effects-in-ch3nh3pbi3-optoelectronic-devices
#10
Chuang Zhang, Dali Sun, Xiaojie Liu, Chuanxiang Sheng, Zeev Valy Vardeny
Organo-lead halide perovskites show excellent optoelectronic properties; however, the unexpected inconsistency in forward/backward I-V characteristics remains a problem for fabricating solar panels. Here we have investigated the reasons behind this "hysteresis" by following the changes in photocurrent/photoluminescence under electric field poling in transverse CH3NH3PbI3-based devices from 300 K to 10 K. We found that the hysteresis disappears at cryogenic temperatures, indicating the "freeze-out" of ionic diffusion contribution...
March 16, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28298120/spontaneous-polarization-of-vapor-deposited-1-butanol-films-and-its-dependence-on-temperature
#11
Irini K Gavra, Alexandra N Pilidi, Athanassios A Tsekouras
Films of 1-butanol were vapor deposited under vacuum conditions at cryogenic temperatures on a polycrystalline platinum foil. Kelvin probe measurements showed the generation of a large negative voltage on the vacuum side of the film relative to its back side in contact with the platinum foil. Voltages across vapor deposited films, which are known to require molecules with an electric dipole moment, were confirmed to be proportional to the amount of gas deposited at a given temperature. Voltages of several hundreds of volts were recorded for films that were a few thousand monolayers thick...
March 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28298101/acetonitrile-cluster-solvation-in-a-cryogenic-ethane-methane-propane-liquid-implications-for-titan-lake-chemistry
#12
L René Corrales, Thomas D Yi, Samantha K Trumbo, David Shalloway, Jonathan I Lunine, David A Usher
The atmosphere of Titan, Saturn's largest moon, exhibits interesting UV- and radiation-driven chemistry between nitrogen and methane, resulting in dipolar, nitrile-containing molecules. The assembly and subsequent solvation of such molecules in the alkane lakes and seas found on the moon's surface are of particular interest for investigating the possibility of prebiotic chemistry in Titan's hydrophobic seas. Here we characterize the solvation of acetonitrile, a product of Titan's atmospheric radiation chemistry tentatively detected on Titan's surface [H...
March 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28288849/whole-blood-selenium-determination-by-inductively-coupled-plasma-mass-spectrometry
#13
Dustin R Bunch, Wendy Cieslak, Sihe Wang
OBJECTIVE: To develop a sensitive method for accurately measuring whole blood selenium and determining an appropriate reference interval for the local Cleveland population. DESIGN AND METHODS: The assay was developed and validated on an inductively coupled plasma mass spectrometry (ICP-MS) with a collision cell. Whole blood trace element free EDTA tubes were used to collect samples for the reference interval study (n=50). Samples were collected after at least 8h fast from healthy adults (76% females) with ages between 19 and 64yr...
March 10, 2017: Clinical Biochemistry
https://www.readbyqxmd.com/read/28288120/0-%C3%AF-phase-controllable-thermal-josephson-junction
#14
Antonio Fornieri, Giuliano Timossi, Pauli Virtanen, Paolo Solinas, Francesco Giazotto
Two superconductors coupled by a weak link support an equilibrium Josephson electrical current that depends on the phase difference ϕ between the superconducting condensates. Yet, when a temperature gradient is imposed across the junction, the Josephson effect manifests itself through a coherent component of the heat current that flows opposite to the thermal gradient for |ϕ| < π/2 (refs 2-4). The direction of both the Josephson charge and heat currents can be inverted by adding a π shift to ϕ...
March 13, 2017: Nature Nanotechnology
https://www.readbyqxmd.com/read/28287218/temperature-dependence-of-metal-enhanced-fluorescence-of-photosystem-i-from-thermosynechococcus-elongatus
#15
Imran Ashraf, Alexander Konrad, Heiko Lokstein, Sepideh Skandary, Michael Metzger, Joseph M Djouda, Thomas Maurer, Pierre M Adam, Alfred J Meixner, Marc Brecht
We report the temperature dependence of metal-enhanced fluorescence (MEF) of individual photosystem I (PSI) complexes from Thermosynechococcus elongatus (T. elongatus) coupled to gold nanoparticles (AuNPs). A strong temperature dependence of shape and intensity of the emission spectra is observed when PSI is coupled to AuNPs. For each temperature, the enhancement factor (EF) is calculated by comparing the intensity of individual AuNP-coupled PSI to the mean intensity of 'uncoupled' PSI. At cryogenic temperature (1...
March 13, 2017: Nanoscale
https://www.readbyqxmd.com/read/28285062/self-assembled-stable-sponge-type-nanocarries-for-brucea-javanica-oil-delivery
#16
Aihua Zou, Yawen Li, Yiyin Chen, Angelina Angelova, Vasil M Garamus, Na Li, Markus Drechsler, Borislav Angelov, Yabin Gong
Sponge-type nanocarriers (spongosomes) are produced upon dispersion of a liquid crystalline sponge phase formed by self-assembly of an amphiphilic lipid in excess aqueous phase. The inner organization of the spongosomes is built-up by randomly ordered bicontinuous lipid membranes and their surfaces are stabilized by alginate chains providing stealth properties and colloidal stability. The present study elaborates spongosomes for improved encapsulation of Brucea javanica oil (BJO), a traditional Chinese medicine that may strongly inhibit proliferation and metastasis of various cancers...
February 27, 2017: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/28284665/cryopreservation-and-multipotential-characteristics-evaluation-of-a-novel-type-of-mesenchymal-stem-cells-derived-from-small-tailed-han-sheep-fetal-lung-tissue
#17
Caiyun Ma, Changqing Liu, Xiangchen Li, Taofeng Lu, Chunyu Bai, Yanan Fan, Weijun Guan, Yu Guo
Lung mesenchymal stem cells (L-MSCs) characterized by plasticity, reduced relative immune privilege and high anti-fibrosis characteristics play the crucial role in lung tissue regenerative processes. However, up to date, the multi-differentiation potentials and application values of L-MSCs are still uncertain. In the current study, the Small Tailed Han Sheep embryo L-MSCs line from 12 samples, stocking 124 cryogenically-preserved vials, was successfully established by using primary culture and cell cryopreservation techniques...
March 8, 2017: Cryobiology
https://www.readbyqxmd.com/read/28284113/impacts-of-one-century-of-wastewater-discharge-on-soil-transformation-through-ferrolysis-and-related-metal-pollutant-distributions
#18
Folkert van Oort, Médard Thiry, Eddy Foy, Kenji Fujisaki, Ghislaine Delarue, Romain Dairon, Toine Jongmans
Discharge of wastewater leading to notable soil surface contamination is widely reported. But few works highlight the fast dynamics of soils and their morphological transformations that may result from such anthropogenic activities. Near Paris (France), sandy Luvisols were irrigated with urban wastewater since the 1890s. Within and outside the discharge area, the soil cover presents decameter-sized cryogenic structures. We studied macro morphological soil characteristics, soil chemistry and clay mineralogy on selected bulk samples, as well as contemporary pedofeatures and related metal pollutant distribution patterns in soil thin sections from subsurface horizons...
March 8, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28282985/hydrogen-tunneling-above-room-temperature-evidenced-by-infrared-ion-spectroscopy
#19
Mathias Schäfer, Katrin Peckelsen, Mathias Paul, Jonathan Martens, Jos Oomens, Giel Berden, Albrecht Berkessel, Anthony J H M Meijer
While hydrogen tunneling at elevated temperatures has, for instance, often been postulated in biochemical processes, spectroscopic proof is thus far limited to cryogenic conditions, under which thermal reactivity is negligible. We report spectroscopic evidence for H-tunneling in the gas phase at temperatures around 320-350K observed in the isomerization reaction of a hydroxycarbene into an aldehyde. The charge-tagged carbene was generated in situ in a tandem mass spectrometer by decarboxylation of oxo[4-(trimethylammonio)phenyl]acetic acid upon collision induced dissociation...
March 10, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28282493/molecular-and-vibrational-dynamics-in-a-cholesterol-lowering-agent-lovastatin-solid-state-nmr-inelastic-neutron-scattering-and-periodic-dft-study
#20
Pawel Bilski, Kacper Drużbicki, Jacek Jenczyk, Jadwiga Mielcarek, Jan Wasicki
Molecular and vibrational dynamics of a widely used cholesterol-lowering agent, lovastatin, have been studied by combining nuclear magnetic resonance relaxation experiments (1H NMR) with inelastic neutron scattering (INS) and periodic density functional theory modeling (Plane-Wave DFT). According to the complementary experimental study, lovastatin shows no phase transitions down to the cryogenic conditions, while a progressive, stepwise activation of several molecular motions is observed below the room temperature...
March 10, 2017: Journal of Physical Chemistry. B
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