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https://www.readbyqxmd.com/read/28926258/matrix-isolation-studies-of-novel-intermediates-in-the-reaction-of-trimethylaluminum-with-ozone
#1
H Dushanee M Sriyarathne, Bruce S Ault
The thermal reaction of ozone with trimethyl aluminum has been explored using twin jet, concentric jet and merged jet deposition into cryogenic matrixes. Infrared spectroscopy and density functional theory calculations have been employed to identify and characterize the products formed in each case. Together, these deposition techniques provide information over the essentially full course of the gas phase reaction. At short times with twin jet deposition, the primary product is the O atom insertion product (CH3)2AlOCH3...
September 19, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28915484/spontaneous-vesicle-formation-and-vesicle-to-micelle-transition-of-sodium-2-ketooctanate-in-water
#2
Huifang Xu, Na Du, Yawen Song, Shue Song, Wanguo Hou
Single-tailed short-chain alkyl keto-acids/salts, a class of fatty acid/salt derivatives, such as sodium 2-ketooctanate (KOCOONa), are a kind of weakly acid/salt type amphiphiles and plausible prebiotic molecules, and the current understanding of their aggregation behavior in aqueous solutions is still limited. Herein, the aggregation behavior of KOCOONa in aqueous solution was studied by changing its concentration (C), using equilibrium surface tension, conductivity, and fluorescence measurements. The aggregates formed were characterized using freeze-fracture and cryogenic transmission electron microscopy, dynamic light scattering, atomic force microscopy, and confocal laser scanning microscopy...
September 7, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28913527/electron-induced-reactions-in-condensed-mixtures-of-methane-and-ammonia
#3
Sramana Kundu, Vaibhav S Prabhudesai, E Krishnakumar
We demonstrate the efficient formation of carbon-nitrogen bonds starting from CH4 and NH3 on a metal surface at cryogenic temperatures. Electrons in the energy range of 1-90 eV are used to initiate chemical reactions in mixed molecular films of CH4 and NH3 at ∼15 K, and the products are detected by performing temperature programmed desorption (TPD). Extensive dehydrogenation occurs at all energies giving the products CH2NH and HCN in preference to CH3NH2. This is likely to do with the energetics of the reactions and the subsequent stability of these species in the condensed film...
September 15, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28904837/nanotribological-behavior-of-deep-cryogenically-treated-martensitic-stainless-steel
#4
Germán Prieto, Konstantinos D Bakoglidis, Walter R Tuckart, Esteban Broitman
Cryogenic treatments are increasingly used to improve the wear resistance of various steel alloys by means of transformation of retained austenite, deformation of virgin martensite and carbide refinement. In this work the nanotribological behavior and mechanical properties at the nano-scale of cryogenically and conventionally treated AISI 420 martensitic stainless steel were evaluated. Conventionally treated specimens were subjected to quenching and annealing, while the deep cryogenically treated samples were quenched, soaked in liquid nitrogen for 2 h and annealed...
2017: Beilstein Journal of Nanotechnology
https://www.readbyqxmd.com/read/28900717/monitoring-of-oxidative-status-in-three-native-australian-species-during-cold-acclimation-and-cryopreservation
#5
Bryn Funnekotter, Louise Colville, Anja Kaczmarczyk, Shane R Turner, Eric Bunn, Ricardo L Mancera
Three wild species exhibited a significant reduction in antioxidants throughout the cryopreservation protocol, whilst the half-cell reduction potential became more oxidised. Antioxidant content recuperated in recovering shoot tips. Cryopreservation is the most efficient and cost-effective long-term storage solution for the conservation of a wide range of plant species and material. Changes in the levels of antioxidants during the process of cryopreservation are known to reduce post-cryogenic survival due to oxidative stress...
September 12, 2017: Plant Cell Reports
https://www.readbyqxmd.com/read/28898733/manipulation-of-pickering-emulsion-rheology-using-hydrophilically-modified-silica-nanoparticles-in-brine
#6
Christopher Griffith, Hugh Daigle
HYPOTHESIS: Previous work on Pickering emulsions has shown that bromohexadecane-in-water emulsions (50% oil) stabilized with fumed and spherical particles modified with hexadecyl groups develop a noticeable zero shear elastic storage modulus (G'0) of 200Pa and 9Pa, respectively, while in just 50mM NaCl. This high G'0 can be problematic for subsurface applications where brine salinities are higher and on the order of 600mM NaCl. High reservoir salinity coupled with low formation pressure drops could prevent an emulsion with a high G'0 from propagating deep into formation...
September 1, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28898581/trapping-and-structural-characterization-of-the-xno2%C3%A2-no3-x-cl-br-i-exit-channel-complexes-in-the-water-mediated-x-n2o5-reactions-with-cryogenic-vibrational-spectroscopy
#7
Patrick J Kelleher, Fabian S Menges, Joseph W DePalma, Joanna K Denton, Mark A Johnson, Gary H Weddle, Barak Hirshberg, Robert Benny Gerber
The heterogeneous reaction of N2O5 with sea spray aerosols yields the ClNO2 molecule, which is postulated to occur through water-mediated charge separation into NO3- and NO2(+) followed by association with Cl-. Here we address an alternative mechanism where the attack by a halide ion can yield XNO2 by direct insertion in the presence of water. This was accomplished by reacting X-(D2O)n (X=Cl, Br, I) cluster ions with N2O5 to produce ions with stoichiometry [XN2O5]-. These species were cooled in a 20 K ion trap and structurally characterized by vibrational spectroscopy obtained using the D2 messenger tagging technique...
September 12, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28895249/salt-responsive-morphologies-of-ssdna-based-triblock-polyelectrolytes-in-semi-dilute-regime-effect-of-volume-fractions-and-polyelectrolyte-length
#8
Nan K Li, Huihui Kuang, William H Fuss, Stefan Zauscher, Efrosini Kokkoli, Yaroslava G Yingling
A comprehensive study is reported on the effect of salt concentration, polyelectrolyte block length, and polymer concentration on the morphology and structural properties of nanoaggregates self-assembled from BAB single-strand DNA (ssDNA) triblock polynucleotides in which A represents polyelectrolyte blocks and B represents hydrophobic neutral blocks. A morphological phase diagram above the gelation point is developed as a function of solvent ionic strength and polyelectrolyte block length utilizing an implicit solvent ionic strength method for dissipative particle dynamics simulations...
September 12, 2017: Macromolecular Rapid Communications
https://www.readbyqxmd.com/read/28894099/statistical-modelling-predicts-almost-complete-loss-of-major-periglacial-processes-in-northern-europe-by-2100
#9
Juha Aalto, Stephan Harrison, Miska Luoto
The periglacial realm is a major part of the cryosphere, covering a quarter of Earth's land surface. Cryogenic land surface processes (LSPs) control landscape development, ecosystem functioning and climate through biogeochemical feedbacks, but their response to contemporary climate change is unclear. Here, by statistically modelling the current and future distributions of four major LSPs unique to periglacial regions at fine scale, we show fundamental changes in the periglacial climate realm are inevitable with future climate change...
September 11, 2017: Nature Communications
https://www.readbyqxmd.com/read/28893583/facile-formation-of-co-amorphous-atenolol-and-hydrochlorothiazide-mixtures-via-cryogenic-milling-enhanced-physical-stability-dissolution-and-pharmacokinetic-profile
#10
Sakib M Moinuddin, Sida Ruan, Yuting Huang, Qin Gao, Qin Shi, Baochang Cai, Ting Cai
The development of poorly water-soluble drugs faces the risk of low bioavailability and therapeutic efficacy. The co-amorphous drug delivery system has recently gained considerable interest because it offers an alternative approach to modify properties of poorly water-soluble drugs. Herein, we developed a co-amorphous system of atenolol (ATE) and poorly water-soluble hydrochlorothiazide (HCT) by means of cryogenic milling. The co-administration of ATE and HCT has been reported to show therapeutic advantages for patients with uncomplicated hypertension...
September 8, 2017: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/28891955/single-wall-carbon-nanotubes-based-cryogenic-temperature-sensor-platforms
#11
Bogdan Florian Monea, Eusebiu Ilarian Ionete, Stefan Ionut Spiridon, Aurel Leca, Anda Stanciu, Emil Petre, Ashok Vaseashta
We present an investigation consisting of single walled carbon nanotubes (SWCNTs) based cryogenic temperature sensors, capable of measuring temperatures in the range of 2-77 K. Carbon nanotubes (CNTs) due to their extremely small size, superior thermal and electrical properties have suggested that it is possible to create devices that will meet necessary requirements for miniaturization and better performance, by comparison to temperature sensors currently available on the market. Starting from SWCNTs, as starting material, a resistive structure was designed...
September 10, 2017: Sensors
https://www.readbyqxmd.com/read/28890894/risk-of-contamination-of-gametes-and-embryos-during-cryopreservation-and-measures-to-prevent-cross-contamination
#12
REVIEW
Daniel C Joaquim, Eduardo D Borges, Iara G R Viana, Paula A Navarro, Alessandra A Vireque
The introduction and widespread application of vitrification are one of the most important achievements in human assisted reproduction techniques (ART) of the past decade despite controversy and unclarified issues, mostly related to concerns about disease transmission. Guidance documents published by US Food and Drug Administration, which focused on the safety of tissue/organ donations during Zika virus spread in 2016, as well as some reports of virus, bacteria, and fungi survival to cryogenic temperatures, highlighted the need for a review of the way how potentially infectious material is handled and stored in ART-related procedures...
2017: BioMed Research International
https://www.readbyqxmd.com/read/28890267/analysis-of-underivatised-low-volatility-compounds-by-comprehensive-two-dimensional-gas-chromatography-with-a-short-primary-column
#13
Fábio Junior Moreira Novaes, Chadin Kulsing, Humberto Ribeiro Bizzo, Francisco Radler de Aquino Neto, Claudia Moraes Rezende, Philip John Marriott
Comprehensive two-dimensional gas chromatography (GC×GC) approaches with cryogenic modulation were developed for the qualitative analysis of selected low volatility compounds in raw coffee bean extracts, without derivatisation. The approaches employed short first ((1)D) and second ((2)D) dimension columns, specifically a (1)D 65% phenyl methyl siloxane column (11m) and a (2)D 5% phenyl methyl siloxane column (1m), which allowed elution of high molar mass compounds (e.g.>600Da). Solutes included hydrocarbons, fatty acids, diterpenes, tocopherols, sterols, diterpene esters, and di- and triacylglycerides...
August 30, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28888182/instrumentation-for-cryogenic-magic-angle-spinning-dynamic-nuclear-polarization-using-90l-of-liquid-nitrogen-per-day
#14
Brice J Albert, Seong Ho Pahng, Nicholas Alaniva, Erika L Sesti, Peter W Rand, Edward P Saliba, Faith J Scott, Eric J Choi, Alexander B Barnes
Cryogenic sample temperatures can enhance NMR sensitivity by extending spin relaxation times to improve dynamic nuclear polarization (DNP) and by increasing Boltzmann spin polarization. We have developed an efficient heat exchanger with a liquid nitrogen consumption rate of only 90L per day to perform magic-angle spinning (MAS) DNP experiments below 85K. In this heat exchanger implementation, cold exhaust gas from the NMR probe is returned to the outer portion of a counterflow coil within an intermediate cooling stage to improve cooling efficiency of the spinning and variable temperature gases...
September 1, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28886660/a-multi-plate-velocity-map-imaging-design-for-high-resolution-photoelectron-spectroscopy
#15
Steven J Kregel, Glen K Thurston, Jia Zhou, Etienne Garand
A velocity map imaging (VMI) setup consisting of multiple electrodes with three adjustable voltage parameters, designed for slow electron velocity map imaging applications, is presented. The motivations for this design are discussed in terms of parameters that influence the VMI resolution and functionality. Particularly, this VMI has two tunable potentials used to adjust for optimal focus, yielding good VMI focus across a relatively large energy range. It also allows for larger interaction volumes without significant sacrifice to the resolution via a smaller electric gradient at the interaction region...
September 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28886639/internal-energy-dependence-of-the-photodissociation-dynamics-of-o3-using-cryogenic-photoelectron-photofragment-coincidence-spectroscopy
#16
Ben B Shen, Yanice Benitez, Katharine G Lunny, Robert E Continetti
Photoelectron-photofragment coincidence (PPC) spectra of ozonide, O3(-), were measured at 388 nm (Ehν = 3.20 eV) using a newly constructed cryogenic octopole accumulation trap coupled to a PPC spectrometer. The photoelectron spectra reveal three processes consisting of a stable photodetachment channel, and two distinct photodissociation pathways yielding (1) O2 + O(-) or (2) O + O2(-). The first photodissociation pathway is observed in the PPC spectra by photodetachment of the O(-) product by a second photon, and produces electronically excited O2((1)Δg)...
September 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28886623/near-ir-photoluminescence-of-c60
#17
Dmitry V Strelnikov, Bastian Kern, Manfred M Kappes
We have observed that C60+ ions isolated in cryogenic matrixes show distinct near-IR photoluminescence upon excitation in the near-IR range. By contrast UV photoexcitation does not lead to measurable luminescence. The near-IR C60+ photoluminescence is a one-photon process. The emission is mainly concentrated in one band and corresponds to 2A1u<- 2E1g relaxation. We present experimental data for the Stokes shift, power and temperature dependencies as well as the quantum efficiency of the photoluminescence...
September 8, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28881895/balloon-based-esophageal-cryoablation-with-a-novel-focal-ablation-device-dose-finding-and-safety-in-porcine-and-human-models
#18
D W Schölvinck, S Friedland, G Triadafilopoulos, T Valli, M I van Berge Henegouwen, J J G H M Bergman, Bas L A M Weusten
The new Cryoballoon Focal Ablation System (CbFAS), a through-the-scope catheter with battery-powered handle that delivers cryogenic fluid into an inflated balloon, differs from current cryotherapy methods used for treatment of Barrett's epithelium. In this dose-finding study, short- and long-term histopathological effects and safety of the CbFAS were evaluated. Cryoablations with (supra)therapeutic durations (4-24 seconds) were performed in pigs that survived for 12 or 48 hours or 4 or 28 days. Next, cryoablations (durations based on animal data) were performed in normal mucosa of esophageal cancer patients scheduled to undergo esophagectomy...
November 1, 2017: Diseases of the Esophagus: Official Journal of the International Society for Diseases of the Esophagus
https://www.readbyqxmd.com/read/28878240/electron-paramagnetic-resonance-microscopy-using-spins-in-diamond-under-ambient-conditions
#19
David A Simpson, Robert G Ryan, Liam T Hall, Evgeniy Panchenko, Simon C Drew, Steven Petrou, Paul S Donnelly, Paul Mulvaney, Lloyd C L Hollenberg
Magnetic resonance spectroscopy is one of the most important tools in chemical and bio-medical research. However, sensitivity limitations typically restrict imaging resolution to ~ 10 µm. Here we bring quantum control to the detection of chemical systems to demonstrate high-resolution electron spin imaging using the quantum properties of an array of nitrogen-vacancy centres in diamond. Our electron paramagnetic resonance microscope selectively images electronic spin species by precisely tuning a magnetic field to bring the quantum probes into resonance with the external target spins...
September 6, 2017: Nature Communications
https://www.readbyqxmd.com/read/28877649/the-effect-of-hypothermic-and-cryogenic-preservation-on-engineered-neural-tissue
#20
Adam George Edward Day, Kulraj Singh Bhangra, Celia Murray-Dunning, Lara Stevanato, James Phillips
This study explored different approaches to preserve Engineered Neural Tissue (EngNT), a stabilised cellular collagen hydrogel containing columns of aligned Schwann cells for nervous system repair. The ability to preserve EngNT without disrupting cellular and extracellular components and structures is important for clinical translation and commercialisation. Stabilised cellular gels and EngNT constructs were preserved under various conditions and cell survival assessed using live/dead microscopy and metabolic assay...
September 6, 2017: Tissue Engineering. Part C, Methods
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