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https://www.readbyqxmd.com/read/28226223/progress-toward-a-molecular-mechanism-of-water-oxidation-in-photosystem-ii
#1
David J Vinyard, Gary W Brudvig
The active site of photosynthetic water oxidation is the oxygen-evolving complex (OEC) in the photosystem II (PSII) reaction center. The OEC is a Mn4CaO5 cluster embedded in the PSII protein matrix, and it cycles through redox intermediates known as Si states (i = 0-4). Significant progress has been made in understanding the inorganic and physical chemistry of states S0-S3 through experiment and theory. The chemical steps from S3 to S0 are more poorly understood, however, because the identity of the substrate water molecules and the mechanism of O-O bond formation are not well established...
February 2, 2017: Annual Review of Physical Chemistry
https://www.readbyqxmd.com/read/28226222/computer-simulations-of-intrinsically-disordered-proteins
#2
Song-Ho Chong, Prathit Chatterjee, Sihyun Ham
The investigation of intrinsically disordered proteins (IDPs) is a new frontier in structural and molecular biology that requires a new paradigm to connect structural disorder to function. Molecular dynamics simulations and statistical thermodynamics potentially offer ideal tools for atomic-level characterizations and thermodynamic descriptions of this fascinating class of proteins that will complement experimental studies. However, IDPs display sensitivity to inaccuracies in the underlying molecular mechanics force fields...
February 6, 2017: Annual Review of Physical Chemistry
https://www.readbyqxmd.com/read/28226221/development-of-new-density-functional-approximations
#3
Neil Qiang Su, Xin Xu
Kohn-Sham density functional theory has become the leading electronic structure method for atoms, molecules, and extended systems. It is in principle exact, but any practical application must rely on density functional approximations (DFAs) for the exchange-correlation energy. Here we emphasize four aspects of the subject: (a) philosophies and strategies for developing DFAs; (b) classification of DFAs; (c) major sources of error in existing DFAs; and (d) some recent developments and future directions. Expected final online publication date for the Annual Review of Physical Chemistry Volume 68 is April 20, 2017...
February 22, 2017: Annual Review of Physical Chemistry
https://www.readbyqxmd.com/read/28226220/water-oxidation-mechanisms-of-metal-oxide-catalysts-by-vibrational-spectroscopy-of-transient-intermediates
#4
Miao Zhang, Heinz Frei
Water oxidation is an essential reaction of an artificial photosystem for solar fuel generation because it provides electrons needed to reduce carbon dioxide or protons to a fuel. Earth-abundant metal oxides are among the most attractive catalytic materials for this reaction because of their robustness and scalability, but their efficiency poses a challenge. Knowledge of catalytic surface intermediates gained by vibrational spectroscopy under reaction conditions plays a key role in uncovering kinetic bottlenecks and provides a basis for catalyst design improvements...
February 22, 2017: Annual Review of Physical Chemistry
https://www.readbyqxmd.com/read/28220995/development-of-hydrogels-for-regenerative-engineering
#5
REVIEW
Xiaofei Guan, Meltem Avci-Adali, Emine Alarçin, Hao Cheng, Sara Saheb Kashaf, Yuxiao Li, Aditya Chawla, Hae Lin Jang, Ali Khademhosseini
The aim of regenerative engineering is to restore complex tissues and biological systems through convergence in the fields of advanced biomaterials, stem cell science, and developmental biology. Hydrogels are one of the most attractive biomaterials for regenerative engineering, since they can be engineered into tissue mimetic 3D scaffolds to support cell growth due to their similarity to native extracellular matrix. Advanced nano- and micro-technologies have dramatically increased the ability to control properties and functionalities of hydrogel materials by facilitating biomimetic fabrication of more sophisticated compositions and architectures, thus extending our understanding of cell-matrix interactions at the nanoscale...
February 21, 2017: Biotechnology Journal
https://www.readbyqxmd.com/read/28218538/electrochemical-control-of-copper-intercalation-into-nanoscale-bi2se3
#6
Jinsong Zhang, Jie Sun, Yanbin Li, Feifei Shi, Yi Cui
Intercalation of exotic atoms or molecules into the layered materials remains an extensively investigated subject in current physics and chemistry. However, traditionally melt-growth and chemical interaction strategies are either limited by insufficiency of intercalant concentrations or destitute of accurate controllability. Here, we have developed a general electrochemical intercalation method to efficaciously regulate the concentration of zero-valent copper atoms into layered Bi2Se3, followed by a comprehensive experimental characterization and analyses...
February 20, 2017: Nano Letters
https://www.readbyqxmd.com/read/28218318/metal-borohydrides-and-derivatives-synthesis-structure-and-properties
#7
REVIEW
Mark Paskevicius, Lars H Jepsen, Pascal Schouwink, Radovan Černý, Dorthe B Ravnsbæk, Yaroslav Filinchuk, Martin Dornheim, Flemming Besenbacher, Torben R Jensen
A wide variety of metal borohydrides, MBH4, have been discovered and characterized during the past decade, revealing an extremely rich chemistry including fascinating structural flexibility and a wide range of compositions and physical properties. Metal borohydrides receive increasing interest within the energy storage field due to their extremely high hydrogen density and possible uses in batteries as solid state ion conductors. Recently, new types of physical properties have been explored in lanthanide-bearing borohydrides related to solid state phosphors and magnetic refrigeration...
February 20, 2017: Chemical Society Reviews
https://www.readbyqxmd.com/read/28216636/room-temperature-organic-magnets-derived-from-sp-3-functionalized-graphene
#8
Jiří Tuček, Kateřina Holá, Athanasios B Bourlinos, Piotr Błoński, Aristides Bakandritsos, Juri Ugolotti, Matúš Dubecký, František Karlický, Václav Ranc, Klára Čépe, Michal Otyepka, Radek Zbořil
Materials based on metallic elements that have d orbitals and exhibit room temperature magnetism have been known for centuries and applied in a huge range of technologies. Development of room temperature carbon magnets containing exclusively sp orbitals is viewed as great challenge in chemistry, physics, spintronics and materials science. Here we describe a series of room temperature organic magnets prepared by a simple and controllable route based on the substitution of fluorine atoms in fluorographene with hydroxyl groups...
February 20, 2017: Nature Communications
https://www.readbyqxmd.com/read/28214195/first-clinical-case-of-canine-granulocytic-anaplasmosis-in-korea-and-genotypic-analyses-of-anaplasma-phagocytophilum
#9
Seung-Hun Lee, Nara Kim, Dongmi Kwak
A 2-year-old male Jindo dog was presented to a local veterinary clinic for anorexia, lethargy, edema around neck, and vomiting. Based on the clinical history, physical examination, hematology, blood chemistry, serology, and PCR, the dog was diagnosed with canine granulocytic anaplasmosis (CGA). PCR and phylogenetic analyses targeting the 16S rRNA, groEL, and msp2 genes of Anaplasma phagocytophilum revealed that the A. phagocytophilum identified in this study subgrouped into alanine and USA groups according to the groEL and msp2 gene sequences, respectively...
February 3, 2017: Ticks and Tick-borne Diseases
https://www.readbyqxmd.com/read/28211065/the-synthesis-of-weak-acidic-type-hybrid-monolith-via-thiol-ene-click-chemistry-and-its-application-in-hydrophilic-interaction-chromatography
#10
Jiao Zeng, Shengquan Liu, Menglin Wang, Shouzhuo Yao, Yingzhuang Chen
In this work, a porous structure and good permeability monolithic column was polymerized in UV transparent fused-silica capillaries via photo-initiated thiol-ene click polymerization of 2, 4, 6, 8-tetravinyl-2, 4, 6, 8- tetramethylcyclotetrasiloxane (TMTVS), pentaerythritol tetra(3-mercaptopropionate) (PETMP), itaconic acid, respectively, in the presence of porogenic solvents (tetrahydrofuran and methanol) and a initiator (2, 2-dimethoxy-2-phenylacetophenone) (DMPA) within 30 min. The physical properties of this monolith were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy and nitrogen adsorption/desorption measurements...
February 17, 2017: Electrophoresis
https://www.readbyqxmd.com/read/28210931/serotonin-syndrome-from-5-hydroxytryptophan-supplement-ingestion-in-a-9-month-old-labrador-retriever
#11
Hopkins Jennifer, Pardo Mariana, Bischoff Karyn
INTRODUCTION: 5-Hydroxytryptophan (5-HTP) supplements are available over the counter and labeled as sleeping aids and anxiolytics for human use. 5-HTP is a serotonin precursor and overdose can lead to serotonin syndrome. CASE REPORT: A 9-month-old female Labrador retriever was evaluated after ingestion of a 5-HTP supplement. Signs of agitation developed within 1 h of ingestion, and emesis was attempted by the owner with  3% hydrogen peroxide (H2O2) orally. On presentation, the dog was obtunded, bilaterally mydriatic and salivating...
February 16, 2017: Journal of Medical Toxicology: Official Journal of the American College of Medical Toxicology
https://www.readbyqxmd.com/read/28199894/height-and-blood-chemistry-in-adults-with-a-history-of-developmental-arsenic-poisoning-from-contaminated-milk-powder
#12
Takashi Yorifuji, Kenichi Matsuoka, Philippe Grandjean
BACKGROUND: Arsenic poisoning interferes with bone metabolism in laboratory animal studies, and human studies suggest lowered bone mass density at elevated exposures. As the long-term consequences of developmental arsenic toxicity are poorly known, we carried out a clinical pilot study of survivors of the mass arsenic poisoning of bottle-fed infants in Japan in 1955. OBJECTIVES: The purpose was to evaluate the association between developmental arsenic exposure and physical stature and routine blood chemistry reflecting major organ functions more than 50 years later...
February 11, 2017: Environmental Research
https://www.readbyqxmd.com/read/28195722/effects-of-relative-humidity-and-particle-phase-water-on-the-heterogeneous-oh-oxidation-of-2-methylglutaric-acid-aqueous-droplets
#13
Man Mei Chim, Chun Yin Chow, James F Davies, ManNin Chan
Organic aerosols can exist as aqueous droplets, with variable water content depending on their composition and environmental conditions (e.g. relative humidity (RH)). Recent laboratory studies have revealed that oxidation kinetics in highly concentrated droplets can be much slower from those in dilute solutions. However, it remains unclear whether particle phase water affects the formation of reaction products physically and/or chemically. In this work, we investigate the role of particle phase water on the heterogeneous chemistry of aqueous organic droplets consisting of 2-methylglutaric acid (2-MGA), measuring the reaction kinetics and the reaction products upon heterogeneous OH oxidation over a range of RH...
February 14, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28195394/methods-for-evaluating-leaf-surface-free-energy-and-polarity-having-accounted-for-surface-roughness
#14
Justin J Nairn, W Alison Forster
BACKGROUND: Leaf surfaces can have similar wettability, while their roughness and polarity may be very different. This may affect agrochemical bioefficacy, hence there is a need to characterise leaf surface polarity and roughness separately. This paper reviews established surface evaluation techniques and then uses a comprehensive dataset of static contact angles (12 chemical solutions on 15 different species) to compare and contrast them for their ability to characterise leaf surface polarity in isolation from roughness...
February 13, 2017: Pest Management Science
https://www.readbyqxmd.com/read/28192909/local-rank-deficiency-caused-problems-in-analyzing-chemical-data
#15
Mahsa Akbari Lakeh, Róbert Rajkó, Hamid Abdollahi
Multivariate curve resolution (MCR) is a powerful methodology for analyzing chemical data in different application fields such as pharmaceutical analysis, agriculture, food chemistry, environment, and industrial and clinical chemistry. However, MCR results are often complicated by rotational ambiguity, meaning that there is a range of feasible solutions that fulfill the constraints and explain equally well the observed experimental data. Constraints determine the properties of resolved profiles in MCR methods by enforcing different assumptions on data...
February 3, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28192471/the-abundance-and-diversity-of-arbuscular-mycorrhizal-fungi-are-linked-to-the-soil-chemistry-of-screes-and-to-slope-in-the-alpic-paleo-endemic-berardia-subacaulis
#16
Gabriele Casazza, Erica Lumini, Enrico Ercole, Francesco Dovana, Maria Guerrina, Annamaria Arnulfo, Luigi Minuto, Anna Fusconi, Marco Mucciarelli
Berardia subacaulis Vill. is a monospecific genus that is endemic to the South-western Alps, where it grows on alpine screes, which are extreme habitats characterized by soil disturbance and limiting growth conditions. Root colonization by arbuscular mycorrhizal fungi (AMF) is presumably of great importance in these environments, because of its positive effect on plant nutrition and stress tolerance, as well as on structuring the soil. However, there is currently a lack of information on this topic. In this paper, we tested which soil characteristics and biotic factors could contribute to determining the abundance and community composition of AMF in the roots of B...
2017: PloS One
https://www.readbyqxmd.com/read/28186408/functional-microgels-and-microgel-systems
#17
Felix A Plamper, Walter Richtering
Microgels are macromolecular networks swollen by the solvent in which they are dissolved. They are unique systems that are distinctly different from common colloids, such as, e.g., rigid nanoparticles, flexible macromolecules, micelles, or vesicles. The size of the microgel networks is in the range of several micrometers down to nanometers (then sometimes called "nanogels"). In a collapsed state, they might resemble hard colloids but they can still contain significant amounts of solvent. When swollen, they are soft and have a fuzzy surface with dangling chains...
February 10, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28185450/ch3nh3pbi3-xclx-under-different-fabrication-strategies-electronic-structures-and-energy-level-alignment-with-an-organic-hole-transport-material
#18
Rongbin Wang, Chen Wu, Yun Hu, Jitao Li, Pengfei Shen, Qi Wang, Liangsheng Liao, Lijia Liu, Steffen Duhm
We report a photoelectron spectroscopy study on the electronic structure of CH3NH3PbI3-xClx thin films fabricated by physical evaporation from CH3NH3I and PbCl2 precursors, including (1) simultaneously evaporation and (2) sequential evaporation. The results are compared with CH3NH3PbI3-xClx made using conventional solution chemistry (i.e., spin-coating). Depending on the fabrication method, CH3NH3PbI3-xClx films show different chemical constituents in the near-surface region, leading to disparities in their energetic levels...
February 20, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28185188/hapten-anti-hapten-technique-for-two-color-ihc-detection-of-phosphorylated-egfr-and-h2ax-using-primary-antibodies-raised-in-the-same-host-species
#19
Jodi Hagen, David Schwartz, Alexander E Kalyuzhny
Multiplex staining of cell and tissue sections with antibodies raised in the same host species is a serious challenge because of unwanted but inevitable cross-reactivity of secondary antibodies with irrelevant primary antibodies. Several techniques can be used to overcome this obstacle including direct labeling of primary antibodies with fluorescent tags and using tyramide signal amplification. Unfortunately these techniques either lack sensitivity, or require a long multistep protocol which can cause physical damage of specimens...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28183655/differential-cytotoxicity-and-internalization-of-graphene-family-nanomaterials-in-myocardial-cells
#20
Flavio F Contreras-Torres, Andrés Rodríguez-Galván, Carlos E Guerrero-Beltrán, Erick Martínez-Lorán, Eduardo Vázquez-Garza, Nancy Ornelas-Soto, Gerardo García-Rivas
Given the well-known physical properties of graphene oxide (GO), numerous applications for this novel nanomaterial have been recently envisioned to improve the performance of biomedical devices. However, the toxicological assessment of GO, which strongly depends on the used material and the studied cell line, is a fundamental task that needs to be performed prior to its use in biomedical applications. Therefore, the toxicological characterization of GO is still ongoing. This study contributes to this, aiming to synthesize and characterize GO particles and thus investigate their toxic effects in myocardial cells...
April 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
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