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https://www.readbyqxmd.com/read/28230871/an-in-situ-tem-study-of-the-surface-oxidation-of-palladium-nanocrystals-assisted-by-electron-irradiation
#1
Dejiong Zhang, Chuanhong Jin, He Tian, Yalin Xiong, Hui Zhang, Peisheng Qiao, Jie Fan, Ze Zhang, Z Y Li, Jixue Li
The surface oxidation of palladium nanocrystals plays an important role in changing the active sites and subsequently influencing the catalytic reactivity. Such a microscopy study on surface oxidation, down to the atomic scale, is essential for understanding the structure-property correlations of palladium nanocrystal based catalysts. Herein, we present an in situ atomic scale study on the surface oxidation behavior of palladium nanocrystals, which is induced by electron beam irradiation under low oxygen partial pressure and at room temperature inside an environmental transmission electron microscope...
February 23, 2017: Nanoscale
https://www.readbyqxmd.com/read/28228321/immunization-of-bighorn-sheep-against-mannheimia-haemolytica-with-a-bovine-herpesvirus-1-vectored-vaccine
#2
Sai A Batra, Sudarvili Shanthalingam, Gaetano Donofrio, Gary J Haldorson, Shafiqul Chowdhury, Stephen N White, Subramaniam Srikumaran
Mannheimia haemolytica is an important pathogen of pneumonia in bighorn sheep (BHS), consistently causing 100% mortality under experimental conditions. Leukotoxin is the critical virulence factor of M. haemolytica. In a 'proof of concept' study, a vaccine containing leukotoxin and surface antigens of M. haemolytica induced 100% protection in BHS, but required multiple booster doses. Vaccination of wildlife is difficult. BHS, however, can be vaccinated at the time of transplantation, but administration of booster doses is impossible...
February 19, 2017: Vaccine
https://www.readbyqxmd.com/read/28228018/the-dissociative-chemisorption-of-co2-on-ni-100-a-quantum-dynamics-study
#3
Azar Farjamnia, Bret Jackson
A quantum approach based on an expansion in vibrationally adiabatic eigenstates is used to explore the dissociative chemisorption of CO2 on Ni(100). The largest barrier to reaction corresponds to the formation of a bent anionic molecular precursor, bound to the surface by about 0.24 eV. The barrier to dissociation from this state is small. Our computed dissociative sticking probabilities on Ni(100) for molecules in the ground state are in very good agreement with available experimental data, reasonably reproducing the variation in reactivity with collision energy...
February 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28225151/cytopathologic-differential-diagnosis-of-low-grade-urothelial-carcinoma-and-reactive-urothelial-proliferation-in-bladder-washings-a-logistic-regression-analysis
#4
Ebru Cakir, Ulku Kucuk, Emel Ebru Pala, Ozlem Sezer, Rahmi Gokhan Ekin, Ozgur Cakmak
Conventional cytomorphologic assessment is the first step to establish an accurate diagnosis in urinary cytology. In cytologic preparations, the separation of low-grade urothelial carcinoma (LGUC) from reactive urothelial proliferation (RUP) can be exceedingly difficult. The bladder washing cytologies of 32 LGUC and 29 RUP were reviewed. The cytologic slides were examined for the presence or absence of the 28 cytologic features. The cytologic criteria showing statistical significance in LGUC were increased numbers of monotonous single (non-umbrella) cells, three-dimensional cellular papillary clusters without fibrovascular cores, irregular bordered clusters, atypical single cells, irregular nuclear overlap, cytoplasmic homogeneity, increased N/C ratio, pleomorphism, nuclear border irregularity, nuclear eccentricity, elongated nuclei, and hyperchromasia (p ˂ 0...
February 22, 2017: APMIS: Acta Pathologica, Microbiologica, et Immunologica Scandinavica
https://www.readbyqxmd.com/read/28224146/cooperativity-of-axial-and-centre-chirality-in-the-biaryl-disulfoxide-rh-i-catalysed-asymmetric-1-4-addition-of-arylboronic-aids-to-2-cyclohexenone-a-dft-study
#5
Gao-Feng Zha, Hua-Li Qin, Eric Assen B Kantchev
Atropisomeric biaryl disulfoxides contain two independent chiral elements. Previously, the (M,S,S)-diastereomer showed very high catalytic activity and selectivity in the Rh-catalyzed asymmetric 1,4-addition of arylboronic acids to α,β-enones whereas the (M,R,R) counterpart - none. Herein, DFT computations on the key transmetallation (turnover-determining) and carborhodation (enantioselectivity-determining) steps of the catalytic cycle show that the (M,S,S)-ligand gives rise to lower reaction barriers for these elementary steps...
February 22, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28222263/reaction-mechanism-of-covalent-modification-of-phosphatidylethanolamine-lipids-by-reactive-aldehydes-4-hydroxy-2-nonenal-and-4-oxo-2-nonenal
#6
Katarina Vazdar, Danijela Vojta, Davor Margetić, Mario Vazdar
4-hydroxy-2-nonenal (HNE) and 4-oxo-2-nonenal (ONE) are biologically important reactive aldehydes formed during oxidative stress in phospholipid bilayers. They are highly reactive species due to presence of several reaction centers and can react with amino acids in peptides and proteins, as well as phosphoethanolamine (PE) lipids, thus modifying their biological activity. The aim of this work is to study in a molecular detail the reactivity of HNE and ONE towards PE lipids in a simplified system containing only lipids and reactive aldehydes in dichloromethane as an inert solvent...
February 21, 2017: Chemical Research in Toxicology
https://www.readbyqxmd.com/read/28222257/an-iron-ii-ylide-complex-as-a-masked-open-shell-iron-alkylidene-species-in-its-alkylidene-transfer-reactions-with-alkenes
#7
Jian Liu, Lianrui Hu, Lei Wang, Hui Chen, Liang Deng
Transition-metal alkylidenes are important reactive organometallic intermediates, and our current knowledge on them has been mainly restricted to those with closed-shell electronic configurations. In this study, we present the exploration on open-shell iron alkylidenes with a weak-field tripodal amido-phosphine-amido ligand. We found that a high-spin (amido-phosphine-amido)iron(II) complex can react with (p-tolyl)2CN2 to afford a high-spin (amido-ylide-amido)iron(II) complex, 2, which could transfer its alkylidene moiety to a variety of alkenes, either the electron-rich or electron-deficient ones, to form cyclopropane derivatives...
February 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28222056/physical-activity-sedentary-behavior-and-inflammatory-and-hemostatic-markers-in-men
#8
Tessa J Parsons, Claudio Sartini, Paul Welsh, Naveed Sattar, Sarah Ash, Lucy T Lennon, S Goya Wannamethee, I-Min Lee, Peter H Whincup, Barbara J Jefferis
PURPOSE: This study aimed to determine whether higher levels of physical activity (PA) and less sedentary behavior (SB) are associated with less inflammation, indicated by inflammatory and hemostatic biomarkers, in older men. METHODS: A cross-sectional study of 1139 men, from the British Regional Heart Study (mean ± SD age = 78 ± 5 yr), and longitudinal analyses of 490 men with two PA measures 1 yr apart were used in this study. Single fasting venous blood samples were analyzed for several biomarkers...
March 2017: Medicine and Science in Sports and Exercise
https://www.readbyqxmd.com/read/28221765/design-of-macroscopically-ordered-liquid-crystalline-hydrogel-columns-knitted-with-nanosilver-for-topical-applications
#9
Sudha Janardhanan Devaki, Reshma Lali Raveendran, Nishanth Kumar Sasidharan
Design of liquid crystalline hydrogels knitted with silver nanoparticles in macroscopic ordering are becoming subject of research interest due to their promising multifunctional applications in biomedical and opto-electronic applications. The present work describes the development of liquid crystalline Schiff-based hydrogel decorated with silver nanoparticles and demonstration of its antifungal applications. Schiff base was prepared from polyglucanaldehyde and chitosan and the former was prepared by the oxidation of amylose (polyglucopyranose) isolated from abundantly available unutilised jackfruit seed starch...
February 21, 2017: Bioconjugate Chemistry
https://www.readbyqxmd.com/read/28220997/highly-stable-sr-free-cobaltite-based-perovskite-cathodes-directly-assembled-on-a-barrier-layer-free-y2-o3-zro2-electrolyte-of-solid-oxide-fuel-cells
#10
Na Ai, Na Li, William D A Rickard, Yi Cheng, Kongfa Chen, San Ping Jiang
Direct assembly is a newly developed technique in which a cobaltite-based perovskite (CBP) cathode can be directly applied to a barrier-layer-free Y2 O3 -ZrO2 (YSZ) electrolyte with no high-temperature pre-sintering steps. Solid oxide fuel cells (SOFCs) based on directly assembled CBPs such as La0.6 Sr0.4 Co0.2 Fe0.8 O3-δ show high performance initially but degrade rapidly under SOFC operation conditions at 750 °C owing to Sr segregation and accumulation at the electrode/electrolyte interface. Herein, the performance and interface of Sr-free CBPs such as LaCoO3-δ (LC) and Sm0...
February 21, 2017: ChemSusChem
https://www.readbyqxmd.com/read/28220699/quantum-mechanical-study-on-the-catalytic-mechanism-of-alkaline-phosphatases
#11
Gabriela L Borosky
Alkaline phosphatases (APs) catalyze the hydrolysis and transphosphorylation of phosphate monoesters. The catalytic mechanism was examined by quantum-mechanical calculations using an active-site model based on the X-ray crystal structure of the human placental AP. Free energies of activation and of reaction for the catalytic steps were evaluated for a series of aryl and alkyl phosphate esters, and the computational results were compared with experimental values available in the literature. Mechanistic observations previously reported in experimental works were rationalized by the present theoretical study, particularly regarding the difference in the rate-determining step between aryl and alkyl phosphates...
February 21, 2017: Journal of Chemical Information and Modeling
https://www.readbyqxmd.com/read/28214747/immunorecognition-magnetic-supports-for-the-development-of-an-electrochemical-immunoassay-for-azaspiracid-detection-in-mussels
#12
Sandra Leonardo, Maria Rambla-Alegre, Ingunn A Samdal, Christopher O Miles, Jane Kilcoyne, Jorge Diogène, Ciara K O'Sullivan, Mònica Campàs
As azaspiracids (AZAs) are being reported from the coastal waters of an increasing number of countries on a global scale, the need for rapid, simple and cost-effective methods to detect these marine toxins and protect seafood consumers' health is becoming evident. A magnetic bead (MB)-based direct immunoassay for the detection of AZAs, using protein G-coated MBs as supports for antibody immobilisation and peroxidase-labelled AZA as a tracer is detailed. A colorimetric approach was first developed to optimise the experimental parameters and establish the cross-reactivity factors for AZA-1-10...
February 10, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28212898/low-serum-iron-is-associated-with-high-serum-intact-fgf23-in-elderly-men-the-swedish-mros-study
#13
Catharina Lewerin, Östen Ljunggren, Herman Nilsson-Ehle, Magnus K Karlsson, Hans Herlitz, Mattias Lorentzon, Claes Ohlsson, Dan Mellström
BACKGROUND: Fibroblast growth factor (FGF23) is a protein that is produced by osteoblasts and osteocytes. Increased serum levels of FGF23 have been associated with increased risks of osteoporotic fractures and cardiovascular disease, particularly in participants with poor renal function. Serum iron (Fe) has been suggested as a regulator of FGF23 homeostasis. OBJECTIVE: To determine whether Fe and iron status are determinants of the levels of intact FGF23 (iFGF23) in elderly men...
February 14, 2017: Bone
https://www.readbyqxmd.com/read/28212797/ca-2-calmodulin-dependent-protein-kinase-ii-in-vascular-smooth-muscle
#14
F Z Saddouk, R Ginnan, H A Singer
Ca(2+)-dependent signaling pathways are central regulators of differentiated vascular smooth muscle (VSM) contractile function. In addition, Ca(2+) signals regulate VSM gene transcription, proliferation, and migration of dedifferentiated or "synthetic" phenotype VSM cells. Synthetic phenotype VSM growth and hyperplasia are hallmarks of pervasive vascular diseases including hypertension, atherosclerosis, postangioplasty/in-stent restenosis, and vein graft failure. The serine/threonine protein kinase Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is a ubiquitous mediator of intracellular Ca(2+) signals...
2017: Advances in Pharmacology
https://www.readbyqxmd.com/read/28212031/bond-activation-and-hydrogen-evolution-from-water-through-reactions-with-m3s4-m-mo-w-and-w3s3-anionic-clusters
#15
Corrine A Kumar, Arjun Saha, Krishnan Raghavachari
Transition metal sulfides (TMS) are being investigated with increased frequency because of their ability to efficiently catalyze the hydrogen evolution reaction. We have studied the trimetallic TMS cluster ions, Mo3S4(-), W3S4(-), and W3S3(-), and probed their efficiency for bond activation and hydrogen evolution from water. These clusters have geometries that are related to the edge sites on bulk MoS2 surfaces that are known to play a role in hydrogen evolution. Using density functional theory, the electronic structures of these clusters and their chemical reactivity with water have been investigated...
February 17, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28212007/catalytic-enantioselective-transformations-involving-c-h-bond-cleavage-by-transition-metal-complexes
#16
Christopher G Newton, Shou-Guo Wang, Caio C Oliveira, Nicolai Cramer
The development of new methods for the direct functionalization of unactivated C-H bonds is ushering in a paradigm shift in the field of retrosynthetic analysis. In particular, the catalytic enantioselective functionalization of C-H bonds represents a highly atom- and step-economic approach toward the generation of structural complexity. However, as a result of their ubiquity and low reactivity, controlling both the chemo- and stereoselectivity of such processes constitutes a significant challenge. Herein we comprehensively review all asymmetric transition-metal-catalyzed methodologies that are believed to proceed via an inner-sphere-type mechanism, with an emphasis on the nature of stereochemistry generation...
February 17, 2017: Chemical Reviews
https://www.readbyqxmd.com/read/28211966/formation-of-organometallic-intermediate-states-in-on-surface-ullmann-couplings
#17
Dennis Barton, Hong-Ying Gao, Philipp Alexander Held, Armido Studer, Harald Fuchs, Nikos L Doltsinis, Johannes Neugebauer
Possible origins of the formation of organometallic intermediates in on-surface Ullmann couplings have been investigated by surface tunneling microscopy (STM) and density functional theory (DFT) calculations. We consider the case of iodobenzenes on the coinage metals Au, Ag and Cu. We found experimental evidence for the formation of surface vacancies and the presence of metal adatoms in these coupling reactions, which are taken as a hint for the reactive extraction of surface atoms by adsorbates. In a second step, we demonstrate by ab initio molecular dynamics calculations for aryl-iodides on copper that metal atoms can be pulled out of the surface to form metalorganic species...
February 17, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28209543/hpa-axis-and-inflammatory-reactivity-to-acute-stress-is-related-with-basal-hpa-axis-activity
#18
Xuejie Chen, Danielle Gianferante, Luke Hanlin, Alexander Fiksdal, Juliana G Breines, Myriam V Thoma, Nicolas Rohleder
INTRODUCTION: Inflammation is drawing attention as pathway between psychosocial stress and health, and basal HPA axis activity has been suggested to exert a consistent regulatory influence on peripheral inflammation. Here we studied the relationship between basal HPA axis activity and inflammatory and HPA axis acute stress reactivity. METHODS: We recruited 48 healthy individuals and collected saliva for diurnal cortisol sampling at 6 points. Participants were previously exposed to the Trier Social Stress Test (TSST) on two consecutive days...
February 6, 2017: Psychoneuroendocrinology
https://www.readbyqxmd.com/read/28209538/new-insight-into-the-catalytic-cycle-about-epoxidation-of-alkenes-by-n2o-over-a-mn-substituted-keggin-type-polyoxometalate
#19
Meng-Xu Jiang, Chun-Guang Liu
Although epoxidation of alkenes by N2O catalyzed by Mn-substituted polyoxometalates (POMs) has been studied both experimental and theoretical methods, a complete catalytic cycle has not been established currently. In the present paper, density functional theory (DFT) calculations were employed to explore possible reaction mechanism about this catalytic cycle. Our DFT studies reveal that the reaction pathway starts from a low-valent Keggin-type POM aquametal derivative [PW11O39Mn(III)H2O](4-). In the presence of N2O pressure, the formation of the active catalytic species [PW11O39Mn(V)O](4-) involves a ligand-substituted reaction about replacement of the aqua ligand with N2O to generation of POM/N2O adduct [PW11O39Mn(III)ON2](4-) and dissociation of N2 from this adduct...
December 21, 2016: Journal of Molecular Graphics & Modelling
https://www.readbyqxmd.com/read/28208109/stability-against-backward-balance-loss-age-related-modifications-following-slip-like-perturbations-of-multiple-amplitudes
#20
Dario Martelli, Federica Aprigliano, Peppino Tropea, Guido Pasquini, Silvestro Micera, Vito Monaco
Falls are one of the most serious problems in the elderly. Although previous studies clearly link the increased risk of falls with ageing, the mechanisms responsible for the modifications of reactive motor behaviours in response to external perturbations are not yet fully understood. This study investigated how the stability against backward balance loss is affected by aging and intensity of perturbations. The Margin of Stability (MoS) was estimated while eight young and eight elderly adults managed three slip-like perturbations of different intensities while walking at the same normalized speed...
February 9, 2017: Gait & Posture
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