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Chemical evolution

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https://www.readbyqxmd.com/read/28339253/distinct-evolutions-of-weyl-fermion-quasiparticles-and-fermi-arcs-with-bulk-band-topology-in-weyl-semimetals
#1
N Xu, G Autès, C E Matt, B Q Lv, M Y Yao, F Bisti, V N Strocov, D Gawryluk, E Pomjakushina, K Conder, N C Plumb, M Radovic, T Qian, O V Yazyev, J Mesot, H Ding, M Shi
The Weyl semimetal phase is a recently discovered topological quantum state of matter characterized by the presence of topologically protected degeneracies near the Fermi level. These degeneracies are the source of exotic phenomena, including the realization of chiral Weyl fermions as quasiparticles in the bulk and the formation of Fermi arc states on the surfaces. Here, we demonstrate that these two key signatures show distinct evolutions with the bulk band topology by performing angle-resolved photoemission spectroscopy, supported by first-principles calculations, on transition-metal monophosphides...
March 10, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28338679/entomopathogenic-bacteria-use-multiple-mechanisms-for-bioactive-peptide-library-design
#2
Xiaofeng Cai, Sarah Nowak, Frank Wesche, Iris Bischoff, Marcel Kaiser, Robert Fürst, Helge B Bode
The production of natural product compound libraries has been observed in nature for different organisms such as bacteria, fungi and plants; however, little is known about the mechanisms generating such chemically diverse libraries. Here we report mechanisms leading to the biosynthesis of the chemically diverse rhabdopeptide/xenortide peptides (RXPs). They are exclusively present in entomopathogenic bacteria of the genera Photorhabdus and Xenorhabdus that live in symbiosis with nematodes delivering them to insect prey, which is killed and utilized for nutrition by both nematodes and bacteria...
April 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28338264/engineering-high-energy-interfacial-structures-for-high-performance-oxygen-involving-electrocatalysis
#3
Chunxian Guo, Yao Zheng, Jingrun Ran, Fangxi Xie, Mietek Jaroniec, Shi-Zhang Qiao
Engineering high-energy interfacial structures for high-performance electrocatalysis is achieved by chemical coupling of active CoO nanoclusters and high-index facet Mn3 O4 nano-octahedrons (hi-Mn3 O4 ). A thorough characterization, including synchrotron-based near edge X-ray absorption fine structure, reveals that strong interactions between both components promote the formation of high-energy interfacial Mn-O-Co species and high oxidation state CoO, from which electrons are drawn by Mn(III) -O present in hi-Mn3 O4 ...
March 24, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28336064/novel-fluorescence-based-biosensors-incorporating-unnatural-amino-acids
#4
Wei Niu, Jiantao Guo
Fluorescent proteins of different colors are useful probes to study protein structure and function, and to investigate cellular events and conditions. Large efforts have focused on engineering new properties into fluorescent proteins via rational design and directed evolution. In addition to applications in imaging of protein expression level and subcellular localization, fluorescent proteins have been increasingly engineered to act as biosensors to track concentrations of small-molecule metabolites, enzyme activities, and protein conformational changes in living cells...
2017: Methods in Enzymology
https://www.readbyqxmd.com/read/28335274/metallic-nanostructures-based-on-dna-nanoshapes
#5
REVIEW
Boxuan Shen, Kosti Tapio, Veikko Linko, Mauri A Kostiainen, Jari Jussi Toppari
Metallic nanostructures have inspired extensive research over several decades, particularly within the field of nanoelectronics and increasingly in plasmonics. Due to the limitations of conventional lithography methods, the development of bottom-up fabricated metallic nanostructures has become more and more in demand. The remarkable development of DNA-based nanostructures has provided many successful methods and realizations for these needs, such as chemical DNA metallization via seeding or ionization, as well as DNA-guided lithography and casting of metallic nanoparticles by DNA molds...
August 10, 2016: Nanomaterials
https://www.readbyqxmd.com/read/28335236/complex-morphology-metal-based-nanostructures-fabrication-characterization-and-applications
#6
REVIEW
Antonella Gentile, Francesco Ruffino, Maria Grazia Grimaldi
Due to their peculiar qualities, metal-based nanostructures have been extensively used in applications such as catalysis, electronics, photography, and information storage, among others. New applications for metals in areas such as photonics, sensing, imaging, and medicine are also being developed. Significantly, most of these applications require the use of metals in the form of nanostructures with specific controlled properties. The properties of nanoscale metals are determined by a set of physical parameters that include size, shape, composition, and structure...
June 6, 2016: Nanomaterials
https://www.readbyqxmd.com/read/28334677/centralized-management-of-sewage-sludge-and-agro-industrial-waste-through-co-composting
#7
M C Gutiérrez, A Serrano, J A Siles, A F Chica, M A Martín
In this research study, the co-composting process of a waste mixture containing strawberry extrudate, fish waste, sewage sludge and bulking agent (SEFW, 190:1:22:90 ratio) was carried out in a dynamic-solid respirometer at pilot scale. The aerobic biodegradability of the mixture was previously ensured in a static-liquid respirometer. The advantages and drawbacks of the SEFW co-composting process were subsequently identified through the determination of respirometric activity and the physical-chemical characterization of the waste, as well as the monitoring of odor emissions...
March 20, 2017: Journal of Environmental Management
https://www.readbyqxmd.com/read/28333437/a-tio2-femnp-core-shell-nanorod-array-photoanode-for-efficient-photoelectrochemical-oxygen-evolution
#8
Desmond E Schipper, Zhenhuan Zhao, Andrew P Leitner, Lixin Xie, Fan Qin, Md Kamrul Alam, Shuo Chen, Dezhi Wang, Zhifeng Ren, Zhiming Wang, Jiming Bao, Kenton H Whitmire
A variety of catalysts have been developed for electrocatalytic oxygen evolution, but very few of them can be readily integrated with semiconducting light absorbers for photoelectrochemical or photocatalytic water splitting. Here, we demonstrate an efficient core/shell photoanode with a highly active oxygen evolution electrocatalyst shell (FeMnP) and semiconductor core (rutile TiO2) for photoelectrochemical oxygen evolution reaction (PEC-OER). Metal-organic chemical vapor deposition (MOCVD) from a single-source precursor was used to ensure good contact between the FeMnP and the TiO2...
March 23, 2017: ACS Nano
https://www.readbyqxmd.com/read/28333371/structure-dependent-behaviours-of-skin-layers-studied-by-atomic-force-microscopy
#9
A C Chang, B H Liu, P L Shao, J D Liao
The multilayer skin provides the physical resistance and strength against the environmental attacks, and consequently plays a significant role in maintaining the mammalian health. Currently, optical microscopy (OM) is the most common method for the research related to skin tissues while with the drawbacks including the possibility of changing the native morphology of the sample with the addition of the chemical or immunological staining and the restricted resolution of images for the direct observation of the tissue structures...
March 23, 2017: Journal of Microscopy
https://www.readbyqxmd.com/read/28332817/basal-plane-ligand-functionalization-on-semiconducting-2h-mos2-monolayers
#10
Qi Ding, Kyle J Czech, Yuzhou Zhao, Jianyuan Zhai, Robert J Hamers, John C Wright, Song Jin
Molybdenum disulfide (MoS2) is a two-dimensional material promising for electronic, optical, and catalytic applications. To fully harness its potential, functionalization is essential to control its properties. However, MoS2 functionalization has been mostly limited to either 1T-phase MoS2 or the edges of 2H-phase MoS2, and the chemistry of covalent functionalization on the basal plane of 2H-MoS2 is poorly understood. Here we report a facile approach to covalently functionalize chemical vapor deposition (CVD) grown 2H-MoS2 monolayers (MLs), as well as mechanically exfoliated MoS2, via thiol conjugation at sulfur vacancies on the basal plane...
March 23, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28331543/experimental-recreation-of-the-evolution-of-lignin-degrading-enzymes-from-the-jurassic-to-date
#11
Iván Ayuso-Fernández, Angel T Martínez, Francisco J Ruiz-Dueñas
BACKGROUND: Floudas et al. (Science 336: 1715) established that lignin-degrading fungi appeared at the end of Carboniferous period associated with the production of the first ligninolytic peroxidases. Here, the subsequent evolution of these enzymes in Polyporales, where most wood-rotting fungi are included, is experimentally recreated using genomic information. RESULTS: With this purpose, we analyzed the evolutionary pathway leading to the most efficient lignin-degrading peroxidases characterizing Polyporales species...
2017: Biotechnology for Biofuels
https://www.readbyqxmd.com/read/28327642/surface-chemistry-of-rare-earth-oxide-surfaces-at-ambient-conditions-reactions-with-water-and-hydrocarbons
#12
Elçin Külah, Laurent Marot, Roland Steiner, Andriy Romanyuk, Thomas A Jung, Aneliia Wäckerlin, Ernst Meyer
Rare-earth (RE) oxide surfaces are of significant importance for catalysis and were recently reported to possess intrinsic hydrophobicity. The surface chemistry of these oxides in the low temperature regime, however, remains to a large extent unexplored. The reactions occurring at RE surfaces at room temperature (RT) in real air environment, in particular, in presence of polycyclic aromatic hydrocarbons (PAHs), were not addressed until now. Discovering these reactions would shed light onto intermediate steps occurring in automotive exhaust catalysts before reaching the final high operational temperature and full conversion of organics...
March 22, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28327586/cellular-preservation-of-musculoskeletal-specializations-in-the-cretaceous-bird-confuciusornis
#13
Baoyu Jiang, Tao Zhao, Sophie Regnault, Nicholas P Edwards, Simon C Kohn, Zhiheng Li, Roy A Wogelius, Michael J Benton, John R Hutchinson
The hindlimb of theropod dinosaurs changed appreciably in the lineage leading to extant birds, becoming more 'crouched' in association with changes to body shape and gait dynamics. This postural evolution included anatomical changes of the foot and ankle, altering the moment arms and control of the muscles that manipulated the tarsometatarsus and digits, but the timing of these changes is unknown. Here, we report cellular-level preservation of tendon- and cartilage-like tissues from the lower hindlimb of Early Cretaceous Confuciusornis...
March 22, 2017: Nature Communications
https://www.readbyqxmd.com/read/28322493/trimetallic-oxyhydroxide-coralloids-for-efficient-oxygen-evolution-electrocatalysis
#14
Yecan Pi, Qi Shao, Pengtang Wang, Fan Lv, Shaojun Guo, Jun Guo, Xiaoqing Huang
Trimetallic oxyhydroxides are one of the most effective materials for oxygen evolution reaction (OER) catalysis, a key process for water splitting. Herein, we describe a facile wet-chemical method to directly grow a series of coralloid trimetallic oxyhydroxides on arbitrary substrates such as nickel foam (NF) and carbon nanotubes (CNTs). The amount of iron in these oxyhydroxide sponges on NF and CNTs was precisely controlled, revealing that the electrocatalytic activity of the WCoFe trimetallic oxyhydroxides depends on the Fe amount in a volcano-like fashion...
March 21, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28320490/effect-of-cu-on-nanoscale-precipitation-evolution-and-mechanical-properties-of-a-fe-nial-alloy
#15
Qin Shen, Hao Chen, Wenqing Liu
The microstructural evolution of precipitation in two model alloys, Fe-NiAl and Fe-NiAl-Cu, was investigated during aging at 500°C for different times using atom probe tomography (APT). The APT results reveal that the addition of Cu effectively increases the number density of NiAl precipitates. This is attributed to Cu promoting the nucleation of NiAl particles by increasing the chemical driving force and decreasing the interfacial energy. The NiAl precipitates of the Fe-NiAl-Cu alloy grow and coarsen at a slower rate than that of the Fe-NiAl alloy, mainly due to the slower diffusion rate of the Cu atoms...
March 21, 2017: Microscopy and Microanalysis
https://www.readbyqxmd.com/read/28319856/systems-biology-solutions-for-biochemical-production-challenges
#16
REVIEW
Anne Sofie Lærke Hansen, Rebecca M Lennen, Nikolaus Sonnenschein, Markus J Herrgård
There is an urgent need to significantly accelerate the development of microbial cell factories to produce fuels and chemicals from renewable feedstocks in order to facilitate the transition to a biobased society. Methods commonly used within the field of systems biology including omics characterization, genome-scale metabolic modeling, and adaptive laboratory evolution can be readily deployed in metabolic engineering projects. However, high performance strains usually carry tens of genetic modifications and need to operate in challenging environmental conditions...
March 16, 2017: Current Opinion in Biotechnology
https://www.readbyqxmd.com/read/28316606/a-comprehensive-phenotypic-investigation-of-the-pod-shattering-syndrome-in-common-bean
#17
Maria L Murgia, Giovanna Attene, Monica Rodriguez, Elena Bitocchi, Elisa Bellucci, Davide Fois, Laura Nanni, Tania Gioia, Diego M Albani, Roberto Papa, Domenico Rau
Seed shattering in crops is a key domestication trait due to its relevance for seed dispersal, yield, and fundamental questions in evolution (e.g., convergent evolution). Here, we focused on pod shattering in common bean (Phaseolus vulgaris L.), the most important legume crop for human consuption in the world. With this main aim, we developed a methodological pipeline that comprises a thorough characterization under field conditions, including also the chemical composition and histological analysis of the pod valves...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28316369/understanding-the-electrochemical-formation-and-decomposition-of-li2o2-and-lioh-with-operando-x-ray-diffraction
#18
Zhaolong Li, Swapna Ganapathy, Yaolin Xu, Jouke R Heringa, Quanyao Zhu, Wen Chen, Marnix Wagemaker
The lithium air, or Li-O2, battery system is a promising electrochemical energy storage system because of its very high theoretical specific energy, as required by automotive applications. Fundamental research has resulted in much progress in mitigating detrimental (electro)chemical processes; however, the detailed structural evolution of the crystalline Li2O2 and LiOH discharge products, held at least partially responsible for the limited reversibility and poor rate performance, is hard to measure operando under realistic electrochemical conditions...
February 28, 2017: Chemistry of Materials: a Publication of the American Chemical Society
https://www.readbyqxmd.com/read/28314937/phylogenetic-analysis-of-idd-gene-family-and-characterization-of-its-expression-in-response-to-flower-induction-in-malus
#19
Sheng Fan, Dong Zhang, Libo Xing, Siyan Qi, Lisha Du, Haiqin Wu, Hongxia Shao, Youmei Li, Juanjuan Ma, Mingyu Han
Although INDETERMINATE DOMAIN (IDD) genes encoding specific plant transcription factors have important roles in plant growth and development, little is known about apple IDD (MdIDD) genes and their potential functions in the flower induction. In this study, we identified 20 putative IDD genes in apple and named them according to their chromosomal locations. All identified MdIDD genes shared a conserved IDD domain. A phylogenetic analysis separated MdIDDs and other plant IDD genes into four groups. Bioinformatic analysis of chemical characteristics, gene structure, and prediction of protein-protein interactions demonstrated the functional and structural diversity of MdIDD genes...
March 17, 2017: Molecular Genetics and Genomics: MGG
https://www.readbyqxmd.com/read/28306551/master-equations-and-the-theory-of-stochastic-path-integrals
#20
Markus F Weber, Erwin Frey
This review provides a pedagogic and self-contained introduction to master equations and to their representation by path integrals. Since the 1930s, master equations have served as a fundamental tool to understand the role of fluctuations in complex biological, chemical, and physical systems. Despite their simple appearance, analyses of master equations most often rely on low-noise approximations such as the Kramers-Moyal or the system size expansion, or require ad-hoc closure schemes for the derivation of low-order moment equations...
April 2017: Reports on Progress in Physics
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