ALBERT

Description: The exchange bias (EB) effect is observed in Bi 2 Fe 3 AlO 9 polycrystalline ceramics. The EB field ( H EB ), vertical magnetization shift, and coercive field show a strong dependence on the cooling fields. When a larger applied field is used to measure the hysteresis loop, the EB effect is suppressed. The induced spin-glass-like phase via Al 3+ doping is responsible for the EB effect below the spin-glass temperature ( T SG ) of ∼25 K. Moreover, the H EB varies nonmonotonically with temperature above T SG , which is interpreted using a random field model with the exchange coupling between ferromagnetic clusters and an antiferromagnetic phase.

Description: Sulphur is an essential element for life and is ubiquitous in living systems. Yet how the sulphur atom is incorporated into many sulphur-containing secondary metabolites is poorly understood. For bond formation between carbon and sulphur in primary metabolites, the major ionic sulphur sources are the persulphide and thiocarboxylate groups on sulphur-carrier (donor) proteins. Each group is post-translationally generated through the action of a specific activating enzyme. In all reported bacterial cases, the gene encoding the enzyme that catalyses the carbon-sulphur bond formation reaction and that encoding the cognate sulphur-carrier protein exist in the same gene cluster. To study the production of the 2-thiosugar moiety in BE-7585A, an antibiotic from Amycolatopsis orientalis, we identified a putative 2-thioglucose synthase, BexX, whose protein sequence and mode of action seem similar to those of ThiG, the enzyme that catalyses thiazole formation in thiamine biosynthesis. However, no gene encoding a sulphur-carrier protein could be located in the BE-7585A cluster. Subsequent genome sequencing uncovered a few genes encoding sulphur-carrier proteins that are probably involved in the biosynthesis of primary metabolites but only one activating enzyme gene in the A. orientalis genome. Further experiments showed that this activating enzyme can adenylate each of these sulphur-carrier proteins and probably also catalyses the subsequent thiolation, through its rhodanese domain. A proper combination of these sulphur-delivery systems is effective for BexX-catalysed 2-thioglucose production. The ability of BexX to selectively distinguish sulphur-carrier proteins is given a structural basis using X-ray crystallography. This study is, to our knowledge, the first complete characterization of thiosugar formation in nature and also demonstrates the receptor promiscuity of the A. orientalis sulphur-delivery system. Our results also show that co-opting the sulphur-delivery machinery of primary metabolism for the biosynthesis of sulphur-containing natural products is probably a general strategy found in nature.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4082789/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4082789/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sasaki, Eita -- Zhang, Xuan -- Sun, He G -- Lu, Mei-yeh Jade -- Liu, Tsung-lin -- Ou, Albert -- Li, Jeng-yi -- Chen, Yu-hsiang -- Ealick, Steven E -- Liu, Hung-wen -- DK67081/DK/NIDDK NIH HHS/ -- GM035906/GM/NIGMS NIH HHS/ -- GM103403/GM/NIGMS NIH HHS/ -- GM103485/GM/NIGMS NIH HHS/ -- P41 GM103403/GM/NIGMS NIH HHS/ -- P41 GM103485/GM/NIGMS NIH HHS/ -- R01 DK067081/DK/NIDDK NIH HHS/ -- R01 GM035906/GM/NIGMS NIH HHS/ -- England -- Nature. 2014 Jun 19;510(7505):427-31. doi: 10.1038/nature13256. Epub 2014 May 11.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA. ; Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA. ; Division of Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, Texas 78712, USA. ; 1] Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan [2] Genomics Research Center, Academia Sinica, Taipei 115, Taiwan. ; 1] Genomics Research Center, Academia Sinica, Taipei 115, Taiwan [2] Institute of Bioinformatics and Biosignal Transduction, National Cheng-Kung University, Tainan 701, Taiwan. ; Genomics Research Center, Academia Sinica, Taipei 115, Taiwan. ; Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan. ; 1] Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA [2] Division of Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, Texas 78712, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24814342" target="_blank"〉PubMed〈/a〉

Description: Author(s): F. Amiri, G. Sun, H.-J. Mikeska, and T. Vekua The ground-state phase diagram of a Heisenberg spin − 1 2 system on a two-leg ladder with rung alternation is studied by combining analytical approaches with numerical simulations. For the case of ferromagnetic leg exchanges a unique ferrimagnetic ground state emerges, whereas for the case of antiferro… [Phys. Rev. B 92, 184421] Published Fri Nov 20, 2015

Description: Water availability is one of the key environmental factors that control ecosystem functions in temperate forests. Changing climate is likely to alter the ecohydrology and other ecosystem processes that affect forest structures and functions. We constructed a multi-year water budget (2004–2010) and quantified environmental controls on an evapotranspiration (ET) in a 70-year-old mixed-oak woodland forest in northwest Ohio, USA. ET was measured using the eddy-covariance (EC) technique along with precipitation (P), soil volumetric water content (VWC), and shallow groundwater table fluctuation. Three biophysical models were constructed and validated to calculate potential ET (PET) for developing predictive monthly ET models. We found that the annual variability in ET was relatively stable and ranged from 578 mm in 2009 to 670 mm in 2010. In contrast, ET/P was more variable and ranged from 0.60 in 2006 to 0.96 in 2010. Mean annual ET/PET_FAO was 0.64 while mean annual PET_FAO/P was 1.15. Annual ET/PET_FAO was relatively stable, varying from 0.60 in 2005 to 0.72 in 2004. Soil water storage and shallow groundwater recharge during the non-growing season were essential in supplying ET during the growing season when ET exceeded P. Spring leaf area index (LAI), summer photosynthetically active radiation (PAR), and autumn and winter air temperatures (T a ) were the most significant controls of monthly ET. Moreover, LAI regulated ET during the whole growing season and higher temperatures increased ET even during dry periods. Our empirical modeling showed that the interaction of LAI and PET explained 〉90% of the variability in measured ET. Altogether we found that increases in T a and shifts in P distribution are likely to impact forest hydrology by altering shallow groundwater fluctuations, soil water storage, and ET and, consequently, alter the ecosystem functions of temperate forests. This article is protected by copyright. All rights reserved.

Description: The emergence of human infection with a novel H7N9 influenza virus in China raises a pandemic concern. Chicken H9N2 viruses provided all six of the novel reassortant’s internal genes. However, it is not fully understood how the prevalence and evolution of these H9N2 chicken viruses facilitated the genesis of the...

Description: Hydraulic and structural performances are two main subjects in the optimization design of hydraulic machines. This article gives consideration to both hydraulic and structural performances during the optimization process of hydraulic turbine with main and splitter blades on the basis of Multidisciplinary Design Optimization (MDO). The aim is to improve the optimization methods of hydraulic turbine, shorten the development cycle time and ensure stable and efficient operation of the unit. Computational fluid dynamics(CFD) and finite element method(FEM) analysis are combined to improve the overall performance of the runner in the multidisciplinary optimization process. The optimization considers the whole runner including the crown and band to get more accurate results of stress distribution. Open Grip program was used to parameterize runner blade and Bezier curve was used to match the bone line and it changed the blades through transforming the bone lines of different profile. NSG...

Description: Conventional theory predicts that ultrahigh lattice thermal conductivity can only occur in crystals composed of strongly bonded light elements, and that it is limited by anharmonic three-phonon processes. We report experimental evidence that departs from these long-held criteria. We measured a local room-temperature thermal conductivity exceeding 1000 watts per meter-kelvin and an average bulk value reaching 900 watts per meter-kelvin in bulk boron arsenide (BAs) crystals, where boron and arsenic are light and heavy elements, respectively. The high values are consistent with a proposal for phonon-band engineering and can only be explained by higher-order phonon processes. These findings yield insight into the physics of heat conduction in solids and show BAs to be the only known semiconductor with ultrahigh thermal conductivity.

Description: Exsolution lamellae in pyroxene occurring in mantle lherzolite xenoliths in Cenozoic basalts from the Mingxi area, Fujian Province, China, have been investigated by electron backscattered diffraction (EBSD) to determine epitaxial relationships between host and lamellae. Clinopyroxene (diopside) hosts developed two sets of lamellae: one of orthopyroxene (pigeonite-enstatite) lamellae and the other of clinopyroxene (augite) lamellae. Orthopyroxene (enstatite) hosts developed a single set of clinopyroxene (augite) lamellae. A zone crossing method has been used to determine Miller indices of lamellae, which appear as linear traces on thin sections tested by EBSD. In clinopyroxene hosts, the index of orthopyroxene lamellae is (100) and that of clinopyroxene lamellae is ~(401) at 22° to the c -axis. In orthopyroxene hosts, the index of clinopyroxene lamellae is (100). Published high-pressure crystallographic data for compositions approximating those of the lamellae and host are used to compare cell parameters of lamellae and hosts at different pressures. Exact phase boundary theory is applied to estimate the exsolution pressure, and the data uncertainty of composition, cell parameters and orientation of the lamellae have been analyzed. Uncertainties of composition and cell parameters give rise to only small uncertainties in the exsolution pressure, but that of the orientation of the lamellae generates large uncertainty. Independent high accuracy measurement of the angle between lamellae and c -axis by TEM or other techniques combined with exact phase boundary theory would give more reliable estimates of exsolution pressure.