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Chemical evolution

Barbara Noziere, David R Hanson
Organic peroxy radicals ("RO2", with R organic) are key intermediates in most oxygen-rich systems where organic compounds are oxidized (natural environment, flames, combustion engines, living organisms…). But, until recently, techniques able to monitor simultaneously and distinguish between RO2 species ("speciated" detection) have been scarce, which has limited the understanding of complex systems containing these radicals. Mass Spectrometry using proton transfer ionization has been shown previously to detect individual gas-phase RO2 separately...
October 16, 2017: Journal of Physical Chemistry. A
Cole Mathis, Sanjay N Ramprasad, Sara Imari Walker, Niles Lehman
Cooperation is essential for evolution of biological complexity. Recent work has shown game theoretic arguments, commonly used to model biological cooperation, can also illuminate the dynamics of chemical systems. Here we investigate the types of cooperation possible in a real RNA system based on the Azoarcus ribozyme, by constructing a taxonomy of possible cooperative groups. We construct a computational model of this system to investigate the features of the real system promoting cooperation. We find triplet interactions among genotypes are intrinsically biased towards cooperation due to the particular distribution of catalytic rate constants measured empirically in the real system...
October 16, 2017: Life
Daorui Han, Martin Wiesmeier, Richard T Conant, Anna Kühnel, Zhigang Sun, Ingrid Kögel-Knabner, Ruixing Hou, Peifei Cong, Rubiao Liang, Zhu Ouyang
Agricultural soils are widely recognized to be capable of carbon sequestration that contributes to mitigating CO2 emissions. To better understand soil organic carbon (SOC) stock dynamics and its driving and controlling factors corresponding with a period of rapid agronomic evolution from the 1980s to the 2010s in the North China Plain (NCP), we collected data from two region-wide soil sampling campaigns (in the 1980s and 2010s) and conducted an analysis of the controlling factors using the random forest model...
September 7, 2017: Global Change Biology
Kirtiman Deo Malviya, Chandan Srivastava, Kamanio Chattopadhyay
The present work reports the nature of the evolution of an array of nanoparticles during the synthesis of alloy nanoparticles of Ag-60 at%Cu by the co-reduction of metal salt precursors using NaBH4 in an aqueous medium. This was achieved by studying samples extracted at different intervals of time from the reaction bath. The microstructural characterization reveals that at the initial stage of synthesis, a single-phase solid solution of alloy nanoparticles of very small sizes was formed; however, as the reaction time increases, a network of chains of nanoparticles evolves containing particles rich in either Ag or Cu...
October 16, 2017: Physical Chemistry Chemical Physics: PCCP
Piero Barbanti, Patrizia Ferroni
Discovered by serendipity, onabotulinum toxin A (BoNT-A) is the only US Food and Drug Administration-approved treatment for the prevention of chronic migraine (CM), one of the most disabling and burdensome human conditions. Its efficacy, safety and tolerability, proved by the largest and longest migraine therapeutic trial (the Phase III Research Evaluating Migraine Prophylaxis Therapy program [PREEMPT]), have been replicated by various real-life studies also in the presence of medication overuse. The benefit of BoNT-A prophylaxis is likely due to its ability to counteract peripheral and central nociceptive sensitization through reversible chemical denervation of pericranial sensitive afferents...
2017: Journal of Pain Research
Wolf Haberer, Thomas Schmitt, Peter Schreier, Anne-Katrin Eggert, Josef K Müller
In burying beetles, Nicrophorus spp. (Coleoptera: Silphidae: Nicrophorinae) mate finding is mediated by male produced volatile compounds. To date, pheromone components of only two species have been identified. In an attempt to better understand the evolution of male pheromone signaling in burying beetles, we investigated the male released volatiles of ten Nicrophorus species and one closely related nicrophorine species, Ptomascopus mori. Volatiles emitted by calling males were collected in the laboratory by means of solid phase micro extraction and analyzed using gas chromatography coupled with mass spectrometry...
October 14, 2017: Journal of Chemical Ecology
Marie-Agnès Coutellec
Mollusc shells, beyond the treasure of information inherently conveyed through their morphology and chemical composition also have the capacity to preserve DNA sequences over the long term in their inner structure. This has been clearly demonstrated for the first time in the study published in this issue of Molecular Ecology Resources by Der Sarkissian et al. (). With a methodology specifically dedicated to ancient DNA and solid matrices, the authors were able to successfully extract and amplify DNA from marine shells spanning the last 7,000 years...
September 2017: Molecular Ecology Resources
Dennis M Krüger, Adrian Glas, David Bier, Nicole Pospiech, Kerstin Wallraven, Laura Dietrich, Christian Ottmann, Oliver Koch, Sven Hennig, Tom N Grossmann
Macrocyclic peptides can interfere with challenging biomolecular targets including protein‒protein interactions. Whereas there are various approaches that facilitate the identification of peptide-derived ligands, their evolution into higher affinity binders remains a major hurdle. We report a virtual screen based on molecular docking that allows the affinity maturation of macrocyclic peptides taking non-natural amino acids into consideration. These macrocycles bear large and flexible substituents which usually complicate the use of docking approaches...
October 13, 2017: Journal of Medicinal Chemistry
Subramanian Natarajan, S Anantharaj, Rajesh J Tayade, Hari C Bajaj, Subrata Kundu
A facile way of recovering 3d transition metals of industrial importance from spent lithium-ion batteries (LIBs) without using any surfactants has been developed. Mn- and Co-rich spent LIBs were chosen as sustainable sources for recovering the oxides of the respective elements. The physical dismantling of Li-ion batteries, chemical leaching with 2 M acetic acid, precipitation with ammonium carbonate, hydrothermal conditioning and calcination at 650 °C led to the facile formation of spherical spinel MnCo2O4 with very high morphological selectivity...
October 13, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Fu-Ying Lee, Zong-Zhe Wu, Li-Chi Kao, Feng-Mei Chang, Sheng-Wen Chen, Shiu-Ko JangJian, Hui-Yu Cheng, Wei-Liang Chen, Yu-Ming Chang, Kuang Yao Lo
Further scale down the dimension of silicon-based integrated circuit is a crucial trend in semiconductor fabrication. One of the most critical issues in the nano-device fabrication is to confirm the atomic structure evolution of the ultrathin shallow junction. In this report, UV Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge structure (XANES) and reflective second harmonic generation (RSHG) are utilized to monitor the pulse laser induced atomic structure evolution of ultralow-energy high-dose Boron implanted Si(110) at room and cold substrate temperature...
October 12, 2017: Scientific Reports
Jennifer R Lamb, Jason P Holland
The advent of hybrid cameras that combine magnetic resonance imaging with either single-photon emission computed tomography (SPECT/MRI) or positron-emission tomography (PET/MRI) has stimulated growing interest in developing multi-modality imaging probes. Countless options are available for fusing magnetically active species with positron- or gamma-ray emitting radionuclides. The initial problem is one of choice: which chemical systems are a suitable basis for developing hybrid imaging agents? Any attempt to answer this question must also address how the physical, chemical, and biological properties of a unified imaging agent can be tailored to ensure that optimum specificity and contrast is achieved simultaneously for both imaging modalities...
October 12, 2017: Journal of Nuclear Medicine: Official Publication, Society of Nuclear Medicine
Wenhai Wang, Long Kuai, Wei Cao, Marko Huttula, Sami Ollikkala, Taru Ahopelto, Ari-Pekka Honkanen, Simo Huotari, Mengkang Yu, Baoyou Geng
A mesoporous MnCo2O4 electrode materials is successfully fabricated for bifunctional oxygen electrocatalysis. The MnCo2O4 exhibits both Co3O4-like activity for oxygen evolution reaction (OER) and Mn2O3-approaching performance for oxygen reduction reaction (ORR). The potential difference between ORR metric and OER metric of MnCo2O4 is as low as 0.84 V. By XANES and XPS investigation, the notable activity is resulted from the preferred MnIV- and CoII-rich surface. Valuably, the products can be obtained in large-scale with the precise chemical components at relatively low temperature...
October 11, 2017: Angewandte Chemie
Yen-Chang Chen, Ang-Yu Lu, Ping Lu, Xiulin Yang, Chang-Ming Jiang, Marina Mariano, Brian Kaehr, Oliver Lin, André Taylor, Ian D Sharp, Lain-Jong Li, Stanley S Chou, Vincent Tung
The emerging molybdenum disulfide (MoS2 ) offers intriguing possibilities for realizing a transformative new catalyst for driving the hydrogen evolution reaction (HER). However, the trade-off between catalytic activity and long-term stability represents a formidable challenge and has not been extensively addressed. This study reports that metastable and temperature-sensitive chemically exfoliated MoS2 (ce-MoS2 ) can be made into electrochemically stable (5000 cycles), and thermally robust (300 °C) while maintaining synthetic scalability and excellent catalytic activity through physical-transformation into 3D structurally deformed nanostructures...
October 12, 2017: Advanced Materials
Tarek Trabelsi, Manoj Kumar, Joseph S Francisco
Complete active space self-consistent field (CASSCF) and multi-reference configuration interaction (MRCI)-based multi-reference calculations have been performed to better understand the ground state properties and the photodis-sociation mechanism of SiH2OO, a silicon analogue of the parent Criegee intermediate, CH2OO. The CASSCF/aug-cc-pV(Q+d)Z results suggest that the ground state of SiH2OO is severely multi-reference in nature, implying that mon-oreference methods such as density functional theory or coupled cluster are incapable of accurately describing this sys-tem...
October 12, 2017: Journal of the American Chemical Society
Anna Wróblewska, Anna Duzynska, Jarosław Judek, Leszek Stobinski, Klaudia Zeranska, Arkadiusz Gertych, Mariusz Zdrojek
We propose a method for monitoring the large-scale homogeneity of the reduction process of graphene oxide. For this purpose, a Raman mapping technique is employed to probe the evolution of the phonon properties of two different graphene oxide (GO) thin films upon controllable thermal reduction. The reduction of GO is reflected by the upshift of the statistical distribution of the relative intensity ratio of the G and D peaks (ID/IG) of the Raman spectra and is consistent with the ratio obtained for chemically reduced GO...
October 12, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Tanmay Banerjee, Frederik Haase, Gökcen Savasci, Kerstin Gottschling, Christian Ochsenfeld, Bettina V Lotsch
We demonstrate photocatalytic hydrogen evolution using COF photosensitizers, with molecular proton reduction catalysts for the first time. With azine linked N2-COF photosensitizer, chloro(pyridine)cobaloxime co-catalyst and TEOA donor, H2 evolution rate of 782 μmol/h/g and TON of 54.4 has been obtained in a water/acetonitrile mixture. PXRD, solid state spectroscopy, EM analysis and quantum-chemical calculations suggest an outer sphere electron transfer from the COF to the co-catalyst which subsequently follows a monometallic pathway of H2 generation from the Co(III)-hydride/Co(II)-hydride species...
October 12, 2017: Journal of the American Chemical Society
Ke Sun, Chonghang Zhao, Cheng-Hung Lin, Eli Stavitski, Garth J Williams, Jianming Bai, Eric Dooryhee, Klaus Attenkofer, Juergen Thieme, Yu-Chen Karen Chen-Wiegart, Hong Gan
Conductive metal sulfides are promising multi-functional additives for future lithium-sulfur (Li-S) batteries. These can increase the sulfur cathode's electrical conductivity to improve the battery's power capability, as well as contribute to the overall cell-discharge capacity. This multi-functional electrode design showed initial promise; however, complicated interactions at the system level are accompanied by some detrimental side effects. The metal sulfide additives with a chemical conversion as the reaction mechanism, e...
October 11, 2017: Scientific Reports
Samy Fenniche, Houda Hammami, Anissa Zaouak
Alopecia areata (AA) is an autoimmune inflammatory disorder of hair, characterized by non-scarring hair loss. 308-nm Excimer lamp (EL) has been reported as one effective modality in the treatment of AA. Khellin is a furanochromone photosensitizer whose chemical structure is close to psoralens and has previously proven its efficacy in vitiligo in association with UVA. We evaluated the efficacy and safety of a combination of topical khellin and 308-nm EL in the treatment of a refractory ophiasic AA (OAA), of 1-year evolution, in a 5-year-old boy...
October 11, 2017: Journal of Cosmetic and Laser Therapy: Official Publication of the European Society for Laser Dermatology
Brandon Wilbanks, Donovan Layton, Sergio Garcia, Cong Trinh
When aiming to produce a target chemical at high yield, titer, and productivity, various combinations of genetic parts available to build the target pathway can generate a large number of strains for characterization. This engineering approach will become increasingly laborious and expensive when seeking to develop desirable strains for optimal production of a large space of biochemicals due to extensive screening. Our recent theoretical development of modular cell (MODCELL) design principles can offer a promising solution for rapid generation of optimal strains by coupling a modular cell and exchangeable production modules in a plug-and-play fashion...
October 10, 2017: ACS Synthetic Biology
Ben J Mans, Jonathan Featherston, Minique H de Castro, Ronel Pienaar
Ticks modulate their hosts' defense responses by secreting a biopharmacopiea of hundreds to thousands of proteins and bioactive chemicals into the feeding site (tick-host interface). These molecules and their functions evolved over millions of years as ticks adapted to blood-feeding, tick lineages diverged, and host-shifts occurred. The evolution of new proteins with new functions is mainly dependent on gene duplication events. Central questions around this are the rates of gene duplication, when they occurred and how new functions evolve after gene duplication...
2017: Frontiers in Cellular and Infection Microbiology
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