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Chemical evolution

Juanita Rodriguez, Tappey H Jones, Petra Sierwald, Paul E Marek, William A Shear, Michael S Brewer, Kevin M Kocot, Jason E Bond
With fossil representatives from the Silurian capable of respiring atmospheric oxygen, millipedes are among the oldest terrestrial animals, and likely the first to acquire diverse and complex chemical defenses against predators. Exploring the origin of complex adaptive traits is critical for understanding the evolution of Earth's biological complexity, and chemical defense evolution serves as an ideal study system. The classic explanation for the evolution of complexity is by gradual increase from simple to complex, passing through intermediate "stepping stone" states...
February 16, 2018: Scientific Reports
Madeline R Luth, Purva Gupta, Sabine Ottilie, Elizabeth A Winzeler
Although many new anti-infectives have been discovered and developed solely using phenotypic cellular screening and assay optimization, most researchers recognize that structure-guided drug design is more practical and less costly. In addition, a greater chemical space can be interrogated with structure-guided drug design. The practicality of structure-guided drug design has launched a search for the targets of compounds discovered in phenotypic screens. One method that has been used extensively in malaria parasites for target discovery and chemical validation is in vitro evolution and whole genome analysis (IVIEWGA)...
February 16, 2018: ACS Infectious Diseases
Rahim Bahariqushchi, Rosario Raciti, Ahmet Emre Kasapoğlu, Emre Gür, Meltem Sezen, Eren Kalay, Salvatore Salvatore Mirabella, Atilla Aydınlı
Germanium nanocrystals (Ge NCs) embedded in single and multilayer silicon oxide and silicon nitride matrices have been synthesized using plasma enhanced chemical vapor deposition (PECVD) followed by conventional furnace annealing (CFA) or rapid thermal processing (RTP) in N2 ambient. Compositions of the films were determined by Rutherford backscattering spectrometry (RBS) and X-ray photoelectron spectroscopy (XPS). Formation of nanocrystals under suitable process conditions were observed with high resolution transmission electron microscope (HRTEM) micrographs and Raman spectroscopy...
February 16, 2018: Nanotechnology
Hamed Akbarzadeh, Mohsen Abbaspour, Esmat Mehrjouei, Samira Ramezanzadeh
Recently, it has been reported that small Pt/Co bimetallic nanoclusters into hollow carbon spheres (HCS) show outstanding catalytic performances in deriving biomass fuels due to the small particle size and the homogeneous alloying. Thus, the knowledge about the thermal evolution and stability of the nanoclusters into the HCS has a great importance. We have simulated the heating process beyond the melting point for the bare and encapsulated Pt/Co clusters into the HCS with the different sizes of 55, 147, and 309...
February 15, 2018: Journal of Computational Chemistry
Remi Labetoulle, Stephane Paul, Xavier Roblin
Inflammatory Bowel Diseases, such as Crohn's disease (CD) and Ulcerative Colitis (UC), are widespread diseases (with an estimated 2.2 million Europeans affected), and even populations previously considered 'low risk' (such as Japan and India) are witnessing an increasing incidence. CD is a chronic, progressive immunologically driven disease, with an evolution characterized by succession of periods of progression and remission. New physiopathological pathways are continuously being discovered, the more we understand about how the disease appears and progresses, the more targets become available for the development of novel therapies...
February 15, 2018: Expert Opinion on Investigational Drugs
Alessandro Ceccato, Diego Frezzato
The chemical Langevin equation and the associated chemical Fokker-Planck equation are well-known continuous approximations of the discrete stochastic evolution of reaction networks. In this work, we show that these approximations suffer from a physical inconsistency, namely, the presence of nonphysical probability currents at the thermal equilibrium even for closed and fully detailed-balanced kinetic schemes. An illustration is given for a model case.
February 14, 2018: Journal of Chemical Physics
Bin-Bin Zhang, Cong Wang, Song-Tao Dong, Yang-Yang Lv, Lunyong Zhang, Yadong Xu, Y B Chen, Jian Zhou, Shu-Hua Yao, Yan-Feng Chen
The triangular lattice Na x RhO 2 contains a 4d Rh element with large spin-orbit coupling, and the electron-electron correlation effect is expected to have some novel physical properties. Here we report NaRhO 2 crystal growth by Na 2 CO 3 vapor growth and a series of Na x RhO 2 (0.25 ≤ x ≤ 1) crystals prepared using the chemical desodiation method. Na x RhO 2 reveals a layer structure with the space group R3̅m, and the lattice parameter a evolves from 3.09 to 3.03 Å and c from 15.54 to 15.62 Å when x decreases from 1...
February 15, 2018: Inorganic Chemistry
Sylvin Benjamin Ateba, Sadrine Tchoukouegno Ngeu, Marie Alfrede Mvondo, Job Tchoumtchoua, Charline Florence Awounfack, Liselotte Krenn, Dieudonne Njamen
BACKGROUND: The approval of Taxol® in 1993 marked the great entrance of terpenoids in the anti-cancer area and this drug is still highly important in the treatment of refractory ovarian, breast and other cancers. Over decades, other prominent natural terpenoids have become indispensable for the modern pharmacotherapy of breast cancer. However, given the rapid evolution of drug resistance, effective treatments for advanced breast cancers requiring cytotoxic chemotherapy represent a major unmet clinical need...
February 13, 2018: Current Medicinal Chemistry
Bowei Zhang, Yu Hui Lui, Anand P S Gaur, Bolin Chen, Xiaohui Tang, Zhiyuan Qi, Shan Hu
Efficiency of hydrogen evolution via water electrolysis is mainly impeded by the kinetically sluggish oxygen evolution reaction (OER). Thus, it is of great significance to develop highly active and stable OER catalyst for alkaline water electrolysis or to substitute the more kinetically demanding acidic OER with a facile electron-donating reaction, such that OER is no longer the bottleneck half reaction for either acidic or alkaline water electrolysis. Herein, the hierarchical Fe-Ni phosphide shelled with ultrathin carbon networks on Ni foam (FeNiP@C) is reported and shows exceptional OER activity and enhanced chemical stability in 1M KOH...
February 15, 2018: ACS Applied Materials & Interfaces
Xinyue Wang, Tianbang Li, Makiko Kashio, Yijuan Xu, Makoto Tominaga, Tatsuhiko Kadowaki
Solenopsis invicta , the red imported fire ant, represents one of the most devastating invasive species. To understand their sensory physiology, we identified and characterized their Hymenoptera-specific (Hs) TRPA channel, SiHsTRPA. Consistent with the sensory functions of SiHsTRPA, it is activated by heat, an electrophile, and an insect repellent. Nevertheless, SiHsTRPA does not respond to most of the honey bee ortholog (AmHsTRPA)-activating compounds. The jewel wasp ortholog (NvHsTRPA) is activated by these compounds even though it outgroups both AmHsTRPA and SiHsTRPA...
January 2018: ENeuro
Liu Yuhang, Zeng Jie, Han Di, Wu Kai, Yu Bowen, Chai Songgang, Chen Feng, Qiang Fu
The preparation of graphene oxide (GO) via Hummers method is usually divided into two steps: low temperature oxidation at 35 °C (Step I oxidation) and high temperature oxidation at 98 °C (Step II oxidation). However, the effect of these two steps on the exfoliation capability and chemical structure of graphite oxide (GrO) remains unclear. In this study, both the functional group content of GrO and the entire evolution of interlayer spacing were investigated during the two steps. Step I oxidation is a slowly inhomogeneous oxidation step to remove unoxidized graphite flakes...
February 14, 2018: Nanotechnology
Piyaporn Jaimeewong, Piyalak Ngernchuklin, Napatporn Promsawat, Soodkhet Pojprapai, Sukanda Jiansirisomboon, Methee Promsawat, Anucha Watcharapasorn
This work aims to study the effect of sintering temperature on properties of barium calcium zirconate titanate (BCZT) ceramics. The BCZT is a Pb-free material that shows excellent piezoelectric properties. In this study, BCZT ceramics were prepared from BCZT powders synthesized from barium nitrate, calcium nitrate, zirconium (IV) oxynitrate hydrate, titanium (IV) butoxide and citric acid precursors by the sol-gel auto-combustion method. The BCZT powder was calcined at the temperature ranging from 700 to 1000 °C...
June 1, 2018: Journal of Nanoscience and Nanotechnology
Abdullah M Al-Enizi, Robert M Brooks, M M Ahmad, M M El-Halwany, Mohamed H El-Newehy, Ayman Yousef
Co0 nanoparticles supported on TiO2 nanofibers (nanocomposite) were prepared using a simple electrospinning technique and In-Situ chemical reduction. The synthesized nanocomposite was used to generate hydrogen from ammonia borane (AB). Standard characterization techniques revealed dense distribution of Co0 nanoparticles (Co NPs) onto the TiO2 nanofibers (TiO2 NFs) in the prepared nanocomposite. The introduced nanocomposite has been showed a good catalytic activity as compared to those unsupported Co NPs. As, the hydrogen evolutions for the nanocomposite and Co NPs were 3 mol in 23 min and 47 min, respectively...
July 1, 2018: Journal of Nanoscience and Nanotechnology
Shu-Hong Yu, Chao Gu, Shaojin Hu, Xusheng Zheng, Min-Rui Gao, Ya-Rong Zheng, Lei Shi, Qiang Gao, Xiao Zheng, Wangsheng Chu, Hong-Bin Yao, Junfa Zhu
Ultrathin nanostructures are attractive for diverse applications owing to their unique properties compared to their bulks. Transition metal chalcogenides are promising electrocatalysts, yet there remains difficult to make ultrathin structures (sub-2 nm), and the realization of their chemical doping is even more challenging. Here we describe a soft template mediated colloidal synthesis of Fe-doped NiSe2 ultrathin nanowires (UNWs) with diameter down to 1.7 nm. The synergistic interplay between oleylamine and 1-dodecanethiol is crucial to yield these UNWs...
February 14, 2018: Angewandte Chemie
J Beerwerth, M Storek, D Greim, J Lueg, R Siegel, B Cetinkaya, W Hiller, H Zimmermann, J Senker, R Böhmer
Polycrystalline dimethyl sulfone is studied using central-transition oxygen-17 exchange NMR. The quadrupolar and chemical shift tensors are determined by combining quantum chemical calculations with line shape analyses of rigid-lattice spectra measured for stationary and rotating samples at several external magnetic fields. Quantum chemical computations predict that the largest principal axes of the chemical shift anisotropy and electrical field gradient tensors enclose an angle of about 73°. This prediction is successfully tested by comparison with absorption spectra recorded at three different external magnetic fields...
January 31, 2018: Journal of Magnetic Resonance
Helen L Hicks, David Comont, Shaun R Coutts, Laura Crook, Richard Hull, Ken Norris, Paul Neve, Dylan Z Childs, Robert P Freckleton
Repeated use of xenobiotic chemicals has selected for the rapid evolution of resistance, threatening health and food security at a global scale. Strategies for preventing the evolution of resistance include cycling and mixtures of chemicals and diversification of management. We currently lack large-scale studies that evaluate the efficacy of these different strategies for minimizing the evolution of resistance. Here we use a national-scale data set of occurrence of the weed Alopecurus myosuroides (black-grass) in the United Kingdom to address this...
February 12, 2018: Nature Ecology & Evolution
Xiaoming Song, Yujuan Wen, Yuanyuan Wang, Muhammad Adeel, Yuesuo Yang
The emerging endocrine disrupting chemicals posed high risk and much uncertainty to eco-environment and human health. An analytical method, developed for the simultaneous determination of five steroid estrogens in groundwater and soil based upon solid phase extraction and gas chromatography-mass spectrometry, was applied to investigate the distribution of estrone and 17β-estradiol around Shenyang City with particular focus on penetrating from surface to groundwater in this study. Mean concentrations of the estrone and 17β-estradiol were 55...
January 19, 2018: Chemosphere
Guanglei Liu, Zhanyu Wang, Lianhai Zu, Yan Zhang, Yutong Feng, Shihe Yang, Yu Jia, Songyou Wang, Chi Zhang, Jinhu Yang
The interfacial interactions between nanostructured electrode materials and electrodes play an important part in the performance enhancement of electrochemical energy devices. However, the mechanism of interfacial interactions, as well as its influence on device performance, still remains unclear and is rarely studied. In this work, a CoS2 nanobelt catalyst assembled on Ti foil (CoS2 nanobelts/Ti) is prepared through in situ chemical conversions and chosen as an example to probe the interfacial interactions between the CoS2 catalyst and the Ti electrode, and the correlation between the interfacial interaction and the hydrogen evolution reaction (HER) performance...
February 12, 2018: Nanoscale
Jyoti Bala, Srinivasan Chinnapaiyan, Rajib Kumar Dutta, Hoshang Unwalla
Aptamers are high affinity single-stranded nucleic acid or protein ligands which exhibit specificity and avidity comparable to, or exceeding that of antibodies and can be generated against most targets. The functionality of aptamers is based on their unique tertiary structure, complexity and their ability to attain unique binding pockets by folding. Aptamers are selected in vitro by a process called Systematic Evolution of Ligands by Exponential enrichment (SELEX). The Kd values for the selected aptamer are often in the picomolar to low nanomolar range...
February 12, 2018: RNA Biology
Kaouther Kerboua, Oualid Hamdaoui
The mechanical disturbance created by an ultrasonic wave travelling through a liquid medium induces the formation of cavitation that oscillates due to rarefaction and compression of the wave. The duration and the magnitude of the pressure applied by the ultrasonic wave at each instant would generate a specific impact on the variation of the bubble radius, the temperature, the pressure and the mass inside it. In this paper, a numerical study is conducted to simulate four waveforms (sinusoidal, square, triangular and sawtooth) travelling an aqueous media saturated with oxygen with an amplitude of 1...
April 2018: Ultrasonics Sonochemistry
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