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Physical Chemistry

Alanna Schepartz, Robert Bergman, Robert H Grubbs
Ronald Breslow, Samuel Latham Mitchill Professor of Chemistry at Columbia University, passed away on October 25, 2017, at the age of 86. Breslow made remarkable contributions to the fields of physical-organic and bioorganic chemistry, including biological and biomimetic transformations, and the use of molecular recognition to control reaction selectivity.
December 13, 2017: Angewandte Chemie
Yaoxin Li, Tadeusz L Ogorzalek, Shuai Wei, Xiaoxian Zhang, Pei Yang, Joshua Jasensky, Charles L Brooks, E Neil G Marsh, Zhan Chen
Tethering peptides and proteins to abiotic surfaces has the potential to create biomolecule-functionalized surfaces with useful properties. Commonly used methods of immobilization lack control over the orientation in which biological molecules are covalently or physically bound to the surface, leading to sub-optimal materials. Here we use an engineered beta-galactosidase that can be chemically immobilized on a surface with a well-defined orientation through unique surface-accessible cysteine residues. A combined study using sum frequency generation (SFG) vibrational spectroscopy and coarse grained molecular dynamics (MD) simulations was performed to determine the effects of enzyme immobilization site and abiotic surface chemistry on enzyme surface orientation, surface coverage, and catalytic activity...
December 13, 2017: Physical Chemistry Chemical Physics: PCCP
Vivian F Crum, Shaelyn R Casey, Justin R Sparks
Light-matter strong coupling is a promising route toward the modification of chemical and physical properties of molecules without formally changing their constituent atoms, bonds, or geometry. The photon-mediated hybridization of vibrational modes of two different molecules simultaneously dissolved in solution is demonstrated in a solution of hexacyanocobaltate(iii) and hexacyanoferrate(ii) ions. The formation of polaritons with tunable contributions from the bonds of each molecule is shown to be feasible within practical concentration ranges for cavity controlled chemistry...
December 13, 2017: Physical Chemistry Chemical Physics: PCCP
Steven T Bramwell
Many liquid or liquid-like states remain stable down to temperatures well below the interaction energy scale, where mean-field theory predicts an ordering transition. In magnetism, correlated states such as spin ice and the spin liquid have been described as Coulomb phases, governed by an emergent gauge principle. In the physical chemistry of polar liquids, systems that evade mean field order have, in contrast, been described by Onsager's theory of the reaction field. Here we observe that in the low-temperature limit, Onsager's theory may be cast as a prototypical theory of the Coulomb phase...
December 12, 2017: Nature Communications
Leah C Frenette, Todd D Krauss
Studies of the fundamental physics and chemistry of colloidal semiconductor nanocrystal quantum dots (QDs) have been central to the field for over 30 years. Although the photophysics of QDs has been intensely studied, much less is understood about the underlying chemical reaction mechanism leading to monomer formation and subsequent QD growth. Here we investigate the reaction mechanism behind CdSe QD synthesis, the most widely studied QD system. Remarkably, we find that it is not necessary for chemical precursors used in the most common synthetic methods to directly react to form QD monomers, but rather they can generate in situ the same highly reactive Cd and Se precursors that were used in some of the original II-VI QD syntheses decades ago, i...
December 12, 2017: Nature Communications
Luigi Santacroce, Lucrezia Bottalico, Ioannis Alexandros Charitos
Background: In the pre-Hellenistic period, the concept of medicine was not well-defined. Usually, a disease was considered as a divine punishment and its treatment was devolved to the priests who asked for healing from the divinities. The only job that could be compared to medical practice was a kind of itinerant medicine, derived from the Egyptian therapeutic tradition based only on practical experience and performed by people that knew a number of remedies, mostly vegetable, but without any theoretical bases about the possible mechanisms of action...
December 12, 2017: Medicines (Basel, Switzerland)
Vincenzo De Filippis, Laura Acquasaliente, Giulia Pontarollo, Daniele Peterle
The advent of recombinant DNA technology allowed to site-specifically insert, delete or mutate almost any amino acid in a given protein, significantly improving our knowledge of protein structure, stability and function. Nevertheless, a quantitative description of the physical and chemical basis that makes a polypeptide chain to efficiently fold into a stable and functionally active conformation is still elusive. This mainly originates from the fact that nature combined, in a yet unknown manner, different properties (i...
December 12, 2017: Biotechnology and Applied Biochemistry
Herbert Jäckle, Carmen Rotte, Peter Gruss
Manfred Eigen turned 90 on May 9th, 2017. He celebrated with a small group of colleagues and friends on behalf of the many inspired by him over his lifetime-whether scientists, artists, or philosophers. A small group of friends, because many-who by their breakthroughs have changed the face of science in different research areas-have already died. But it was a special day, devoted to the many genius facets of Manfred Eigen's oeuvre, and a day to highlight the way in which he continues to exude a great, vital and unbroken passion for science as well as an insatiable curiosity beyond his own scientific interests...
December 11, 2017: European Biophysics Journal: EBJ
Lucas R Parent, Evangelos Bakalis, Maria Proetto, Yiwen Li, Chiwoo Park, Francesco Zerbetto, Nathan C Gianneschi
Revolutions in science and engineering frequently result from the development, and wide adoption, of a new, powerful characterization or imaging technique. Beginning with the first glass lenses and telescopes in astronomy, to the development of visual-light microscopy, staining techniques, confocal microscopy, and fluorescence super-resolution microscopy in biology, and most recently aberration-corrected, cryogenic, and ultrafast (4D) electron microscopy, X-ray microscopy, and scanning probe microscopy in nanoscience...
December 11, 2017: Accounts of Chemical Research
Zhisen Liang, Shudi Zhang, Xiaoping Li, Tongtong Wang, Yaping Huang, Wei Hang, Zhilin Yang, Jianfeng Li, Zhongqun Tian
Spectroscopic methods with nanoscale lateral resolution are becoming essential in the fields of physics, chemistry, geology, biology, and materials science. However, the lateral resolution of laser-based mass spectrometry imaging (MSI) techniques has so far been limited to the microscale. This report presents the development of tip-enhanced ablation and ionization time-of-flight mass spectrometry (TEAI-TOFMS), using a shell-isolated apertureless silver tip. The TEAI-TOFMS results indicate the capability and reproducibility of the system for generating nanosized craters and for acquiring the corresponding mass spectral signals...
December 2017: Science Advances
Hatice Genç, Banu Barutca, A Tansu Koparal, Uğurcan Özöğüt, Yücel Şahin, Ender Suvacı
Recently, designed platelet shaped micron particles that are composed of nano primary particles, called MicNo (=Micron+naNo) particles, have been developed to exploit the benefits of nano size, while removing the adverse effects of nanoparticles. It has been shown that MicNo-ZnO particles exhibit both micron and nanosized particle characteristics. Although physical and chemical properties of MicNo-ZnO particles have been studied, their biocompatibility has not yet been evaluated. Accordingly, the research objective of this study was to evaluate in vitro cytotoxicity, genotoxicity and phototoxicity behaviors of designed MicNo-ZnO particles over human epidermal keratinocyte (HaCaT) cells...
December 6, 2017: Toxicology in Vitro: An International Journal Published in Association with BIBRA
Ja-Young Jang, Young June Hong, Junsup Lim, Jin Sung Choi, Eun Ha Choi, Seongman Kang, Hyangshuk Rhim
Plasma, formed by ionization of gas molecules or atoms, is the most abundant form of matter and consists of highly reactive physicochemical species. In the physics and chemistry fields, plasma has been extensively studied; however, the exact action mechanisms of plasma on biological systems, including cells and humans, are not well known. Recent evidence suggests that cold atmospheric plasma (CAP), which refers to plasma used in the biomedical field, may regulate diverse cellular processes, including neural differentiation...
November 30, 2017: Biomaterials
Klaas Wynne
Structuring caused by the mixing of liquids or the addition of solutes to a solvent causes the viscosity to increase. The classical example is mayonnaise: a mixture of two low viscosity liquids, water and oil, is structured through the addition of a surfactant creating a dispersed phase, causing the viscosity to increase a thousandfold. The dramatic increase in viscosity in highly concentrated solutions is a long-standing unsolved problem in physical chemistry. Here we will show that this viscosity increase can be understood in terms of the solute-induced structuring of the first solvation shell leading to a jamming transition at a critical concentration...
December 8, 2017: Journal of Physical Chemistry Letters
Dinh Loc Duong, Seok Joon Yun, Young Hee Lee
Since graphene became available by a scotch tape, a vast class of two-dimensional (2D) van der Waals (vdW) layered materials has been researched intensively. What is more intriguing is that the well-known physics and chemistry of three-dimensional bulk materials are often irrelevant, revealing exotic phenomena in 2D vdW materials. By further constructing heterostructures of these materials in the planar and vertical directions, which can be easily achieved via simple exfoliation techniques, numerous quantum mechanical devices have been demonstrated for fundamental research and technological applications...
December 8, 2017: ACS Nano
Reid A Peterson, Edgar C Buck, Jaehun Chun, Richard C Daniel, Daniel L Herting, Eugene S Ilton, Gregg J Lumetta, Sue B Clark
This paper reviews the origin and chemical and rheological complexity of radioactive waste at the U.S. Department of Energy Hanford Site. The waste, stored in underground tanks, was generated via three distinct processes over decades of plutonium extraction operations. Although close records were kept of original waste disposition, tank-to-tank transfers and conditions that impede equilibrium complicate our understanding of the chemistry, phase composition, and rheology of the waste. Tank waste slurries comprise particles and aggregates from nano to micron scales, with varying densities, morphologies, heterogeneous compositions, and complicated responses to flow regimes and process conditions...
December 7, 2017: Environmental Science & Technology
Ruzhen Xie, Yan Jin, Yao Chen, Wenju Jiang
In this study, activated carbon (AC) was prepared from walnut shell using chemical activation. The surface chemistry of the prepared AC was modified by introducing or blocking certain functional groups, and the role of the different functional groups involved in the copper uptake was investigated. The structural and chemical heterogeneity of the produced carbons are characterized by Fourier transform infrared spectrometry, X-ray photoelectron spectroscopy, Boehm titration method and N2/77 K adsorption isotherm analysis...
December 2017: Water Science and Technology: a Journal of the International Association on Water Pollution Research
Claude Piguet, Lucille Babel, Karine Baudet, Thi Nu Y Hoang, Homayoun Nozary
Since its identification as an independent topic after the first world war, the chemistry of (bio)polymers and macromolecules rapidly benefited from intense synthetic activities driven by contributors focussing on formulation and structural aspects. Satisfying rationalization and predictions concerning polymer organization, stability and reactivity were however delayed until the late fifties, when physical chemists set the basis of an adapted thermodynamic modelling. The recent emergence of metal-containing (bio)organic polymers (i...
December 6, 2017: Chemistry: a European Journal
Toshiaki Tanigaki, Tetsuya Akashi, Akira Sugawara, Katsuya Miura, Jun Hayakawa, Kodai Niitsu, Takeshi Sato, Xiuzhen Yu, Yasuhide Tomioka, Ken Harada, Daisuke Shindo, Yoshinori Tokura, Hiroyuki Shinada
Nanometre-scale magnetic field distributions in materials such as those at oxide interfaces, in thin layers of spintronics devices, and at boundaries in magnets have become important research targets in materials science and applied physics. Electron holography has advantages in nanometric magnetic field observations, and the realization of aberration correctors has improved its spatial resolution. Here we show the subnanometre magnetic field observations inside a sample at 0.67-nm resolution achieved by an aberration-corrected 1...
December 5, 2017: Scientific Reports
Caroline S Fortunato, Benjamin Larson, David A Butterfield, Julie A Huber
At deep-sea hydrothermal vents, microbial communities thrive across geochemical gradients above, at, and below the seafloor. In this study, we determined the gene content and transcription patterns of microbial communities and specific populations to understand the taxonomy and metabolism both spatially and temporally across geochemically different diffuse fluid hydrothermal vents. Vent fluids were examined via metagenomic, metatranscriptomic, genomic binning, and geochemical analyses from Axial Seamount, an active submarine volcano on the Juan de Fuca Ridge in the NE Pacific Ocean, from 2013-2015 at three different vents: Anemone, Marker 33, and Marker 113...
December 4, 2017: Environmental Microbiology
Graeme M Day, Andrew I Cooper
Some of the most successful approaches to structural design in materials chemistry have exploited strong directional bonds, whose geometric reliability lends predictability to solid-state assembly. For example, metal-organic frameworks are an important design platform in materials chemistry. By contrast, the structure of molecular crystals is defined by a balance of weaker intermolecular forces, and small changes to the molecular building blocks can lead to large changes in crystal packing. Hence, empirical rules are inherently less reliable for engineering the structures of molecular solids...
December 4, 2017: Advanced Materials
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