bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural and genetic analysis of START superfamily protein MSMEG_0129 from Mycobacterium smegmatis
Authors: Zheng Shuping , Zhou Ying , Fleming Joy , Zhou Yafeng , Zhang Mengting , Li Shiliang , Li Honglin , Sun Bingqi , Liu Wei , Bi Lijun 
Published: March 2018

Mycobacterium tuberculosis is a notorious pathogen that continues to threaten human health. Rv0164, an antigen of both T‐ and B cells conserved across mycobacteria, and MSMEG_0129, its close homolog in Mycobacterium smegmatis, are predicted members of the START domain superfamily, but their molecular function is unknown. Here, gene knockout studies demonstrate MSMEG_0129 is essential for bacterial growth, suggesting Rv0164 may be a potential drug target. The MSMEG_0129 crystal structure determined at 1.95 Å reveals a fold similar to that in polyketide aromatase/cyclases ZhuI and TcmN from Streptomyces sp. Structural comparisons and docking simulations, however, infer that MSMEG_0129 and Rv0164 are unlikely to catalyze polyketide aromatization/cyclization, but probably play an irreplaceable role during mycobacterial growth, for example, in lipid transfer during cell envelope synthesis.
Intrusion Pattern of the Offshore Kuroshio Branch Current and Its Effects on Nutrient Contributions in the East China Sea
Authors: Wang Wentao , Yu Zhiming , Song Xiuxian , Yuan Yongquan , Wu Zaixing , Zhou Peng , Cao Xihua 
Published: March 2018

AbstractDuring the autumn season of 2014 (October–November), nutrient samples and nitrogen and oxygen isotope samples from the East China Sea (ECS) were collected and analyzed, and auxiliary physical parameters were determined. Distinctive high‐salinity water column conditions with significant haloclines and pycnoclines similar to those observed during the spring were detected at the bottom of the ECS during the autumn. These water column conditions were attributed to the intrusion of the Kuroshio Subsurface Water (KSSW), which then separated into two currents, including the Offshore Kuroshio Branch Current (OKBC). Compared with spring, this intrusion transported higher phosphorus (P) concentrations onto the ECS continental shelf in autumn. However, according to multiple analyses, biogeochemical nitrogen processes are unable to explain the variations in the P concentrations (increase) while assuming that each distinctive water column is consistent. Identifying the water columns by their salinities and P concentrations revealed that the northern ECS water column was similar to the deep KSSW while the southern ECS water column was similar to the shallow KSSW. Therefore, we speculate that the distinctions among the seasonal variations of P‐enriched water masses were attributable to the different intrusion positions of the Kuroshio. The shift of the KSSW intrusion location moved toward the northeast during the autumn relative to the spring. This shift, which was proved by the oceanic vortex data, caused the deeper KSSW water upwelled to the ECS and formed the OKBC, thereby supplying additional P during the autumn.
A Mechanism for the Southward Propagation of Mesoscale Convective Systems Over the Bay of Bengal
Authors: Jain Deepeshkumar , Chakraborty Arindam , Nanjundaiah Ravi S. 
Published: March 2018

AbstractEquatorward propagating precipitation episodes over the Bay of Bengal have been documented in many previous observational studies. Proposed propagation mechanisms include mean surface to midtropospheric wind shear driving the convection orthogonal to the lower tropospheric winds and the gravity currents generated by outflow from convection initiated by the diurnally varying land‐ocean circulations dispersing south. In this study, we perform high‐resolution simulations using the Weather Research and Forecast model capable of resolving mesoscale convective systems during the South Asian summer monsoon season. This mesoscale system is shown to have squall line‐like structure with leading line/trailing stratiform. The rear inflow due to saturated downdraft and jump updraft indicates a gravity current‐like structure. The rear inflow jet produces horizontal momentum tendencies in the direction of propagation. The center of convection is shown to move faster than the midtropospheric winds and at the same speed as that of the rear inflow jet near the surface. These systems are also shown to be tightly coupled to the diurnal land surface heating cycle. We perform additional model simulations with varying horizontal resolution and with the inclusion of cumulus parameterization. A model with cumulus parameterization is unable to simulate the updraft‐downdraft pair and the gravity current structure of this southward propagating mesoscale system. We find that high model resolution is needed to resolve the updraft‐downdraft pair and cumulus parameterization assumptions break down at such high resolutions. Using cloud microphysics exclusively becomes essential in simulating these mesoscale systems.
Unrealized Global Temperature Increase: Implications of Current Uncertainties
Authors: Schwartz Stephen E. 
Published: March 2018

AbstractUnrealized increase in global mean surface air temperature (GMST) may result from the climate system not being in steady state with forcings and/or from cessation of negative aerosol forcing that would result from decreases in emissions. An observation‐constrained method is applied to infer the dependence of Earth's climate sensitivity on forcing by anthropogenic aerosols within the uncertainty on that forcing given by the Fifth (2013) Assessment Report of the Intergovernmental Panel on Climate Change. Within these uncertainty ranges the increase in GMST due to temperature lag for future forcings held constant is slight (0.09–0.19 K over 20 years; 0.12–0.26 K over 100 years). However, the incremental increase in GMST that would result from a hypothetical abrupt cessation of sources of aerosols could be quite large but is highly uncertain, 0.1–1.3 K over 20 years. Decrease in CO2 abundance and forcing following abrupt cessation of emissions would offset these increases in GMST over 100 years by as little as 0.09 K to as much as 0.8 K. The uncertainties quantified here greatly limit confidence in projections of change in GMST that would result from any strategy for future reduction of emissions.
Relations Between Semidiurnal Tidal Variants Through Diagnosing the Zonal Wavenumber Using a Phase Differencing Technique Based on Two Ground‐Based Detectors
Authors: He Maosheng , Chau Jorge L. , Stober Gunter , Li Guozhu , Ning Baiqi , Hoffmann Peter 
Published: March 2018

AbstractThe winter upper atmosphere is associated with semidiurnal tidal variants, referring collectively to enhancements of near‐12 h periodicities, including the lunar tide‐like (M2) periodicity, solar semidiurnal (S2) spectral sidebands, and the quasi‐semidiurnal westward propagating modes with zonal wavenumbers m = 1 and 3 (qSW1 and qSW3). Here we formulate a multipoint technique and implement the technique for a configuration of two midlatitude meteor radars, from Germany and China, to investigate the tidal variants. Statistical results illustrate that the 12 h periodicity is dominated consistently by the expected migrating mode (m = 2) between 2012 and 2016, consistent with the tidal climatology and in turn validating the technique. Our case study of 2013 sudden stratospheric warming reveals that the 11.6 h periodicity is characterized by m = 3, whereas the 12.4 h periodicity is dominated by m = 2 mode with a maximum amplitude 7.5 m/s and also comprises an additional mode m = 1 with a maximum amplitude 3.3 m/s. These observational evidences demonstrate, explicitly and for the first time, that (1) two independently reported categories of the variants, namely, the sidebands and the qSW1/qSW3 enhancements, are two different perspectives of identical phenomena, namely, the secondary waves of nonlinear interactions between SW2 and planetary waves, and (2) while M2 and the qSW1‐associated secondary wave are entangled in the 12.4 h periodicity, M2 is superior to the sideband.
Controlling Interfacial Properties of Lithium‐Ion Battery Cathodes with Alkylphosphonate Self‐Assembled Monolayers
Authors: Nicolau Bruno G. , Petronico Aaron , Letchworth‐Weaver Kendra , Ghadar Yasaman , Haasch Richard T. , Soares Julio A. N. T. , Rooney Ryan T. , Chan Maria K. Y. , Gewirth Andrew A. , Nuzzo Ralph G. 
Published: March 2018

AbstractIn this work, the preparation and characterization of modified LiMn2O4 (LMO) cathodes utilizing chemisorbed alkylphosphonic acids to chemically modify their surfaces are reported. Electrochemical methods to study ionic and molecular mobility through the alkylphosphonate self‐assembled monolayers (SAMs) for different alkyl chain compositions, in order to better understand their impact on the lithium‐ion electrochemistry, are utilized. Electrochemical trends for different chains correlate to trends observed in contact angle measurements and solvation energies obtained from computational methods, indicating that attributes of the microscopic wettability of these interfaces with the battery electrolyte have an important impact on ionic mobility. The effects of surface modification on Mn dissolution are also reported. The alkylphosphonate layer provides an important mode of chemical stabilization to the LMO, suppressing Mn dissolution by 90% during extended immersion in electrolytes. A more modest reduction in dissolution is found upon galvanostatic cycling, in comparison to pristine LMO cathodes. Taken together, the data suggest that alkylphosphonates provide a versatile means for the surface modification of lithium‐ion battery cathode materials allowing the design of specific interfaces through modification of organic chain functionalities.
Nanostructured Unsubstituted Polythiophene Films Deposited Using Oxidative Chemical Vapor Deposition: Hopping Conduction and Thermal Stability
Authors: Lee Sunghwan , Borrelli David C. , Jo Won Jun , Reed Austin S. , Gleason Karen K. 
Published: March 2018

AbstractUnsubstituted polythiophene (PT), a promising material that is challenging to process into thin films due to its intrinsic insolubility, can be synthesized and deposited using unique oxidative chemical vapor deposition (oCVD) at room temperature. The conduction mechanism of nanostructured oCVD PT thin films is illuminated through the investigation of in situ conductivity measurements. It is identified that the 3D variable range hopping process governs the transport of charge carriers in oCVD PT thin films with an activation energy of ≈48 meV regardless of doping concentrations. It is also reported that the thermal stability of oCVD PT largely relies on the doping concentration of the material; oCVD PT demonstrates excellent thermal stability at temperatures up to 160 °C with carrier density values lower than ≈1 × 1017 cm−3, while higher doping leads to a reduction in conductivity at T >≈ 100 °C due to electron–hole recombination. X‐ray photoelectron spectroscopy analyses on the change in the concentrations of dopant anions (Cl− and FeCl4−) support the suggested mechanisms.
Doped, Defect‐Enriched Carbon Nanotubes as an Efficient Oxygen Reduction Catalyst for Anion Exchange Membrane Fuel Cells
Authors: Pham Chuyen Van , Britton Benjamin , Böhm Thomas , Holdcroft Steven , Thiele Simon 
Published: March 2018

AbstractBond polarization of doped atoms and carbon and lattice defects are considered important aspects in the catalytic mechanisms of oxygen reduction reaction (ORR) on heteroatom‐doped carbon catalysts. Previous work on metal‐free catalysts has focused either on bond polarization or lattice defects. Here multi‐heteroatom doped defect‐enriched carbon nanotubes (MH‐DCNTs) that combine both effects to enhance ORR activity are designed. Lattice defects in MH‐DCNTs are enriched by unzipping and length‐shortening of carbon nanotubes, and also by creating carbon vacancies via decomposition of doped F atoms. Electrochemical analysis using rotating disc electrode voltammetry shows that the ORR kinetic current density of MH‐DCNT increases with lattice‐defect density, the latter of which is verified by Raman spectroscopy, while the onset potential increases with annealing temperatures. An optimized MH‐DCNT ORR catalyst exhibits a half‐wave potential of 0.81 V versus reversible hydrogen electrode and limiting current density of 5.0 mA cm−2 at an electrode rotation speed of 1600 rpm in 0.1 m KOH. Further, it is demonstrated that MH‐DCNT, as a cathode catalyst layer in an anion exchange membrane fuel cell (AEMFC), delivers a peak power density of 250 mW cm−2, which is ≈70% the performance of an AEMFC using a conventional Pt/C catalyst.
Spatial Light Patterning of Full Color Quantum Dot Displays Enabled by Locally Controlled Surface Tailoring
Authors: Kang Han‐Lim , Kang Jingu , Won Jong Kook , Jung Su‐Min , Kim Jaehyun , Park Chan Hyuk , Ju Byung‐Kwon , Kim Myung‐Gil , Park Sung Kyu 
Published: March 2018

AbstractQuantum dot (QD) light‐emitting diodes have been intensively investigated as a future display technology owing to their outstanding optoelectronic properties such as narrow spectral bandwidths and high quantum efficiencies. Significant efforts have been made to achieve full color QD light‐emitting diodes (QLEDs) by applying various fine‐patterning technologies to active QD layers. However, the reported patterning methods generally require high processing cost and complex facilities which have limited their wide adoption in industrial‐scale display applications. In this study, a fine patterning method is presented by employing spatial light‐assisted and locally controlled surface tailoring. The chemical functionality of an interfacial polyethyleneimine (PEI) layer between ZnO and the QD layers is locally controlled by spatial light patterning (SLP), which is simultaneously used as a charge transfer layer and an anchoring agent for the selected QD nanoparticles. The versatility of this approach is demonstrated by patterning crossed stripes and multicolor QLED devices on selectively patterned PEI layers with a maximum luminescence of 1950 cd m−2 and a current efficiency of 2.9 cd A−1. The SLP process described herein is a general approach for fabricating full color QLEDs with marginal toxicity. This process is compatible with the standard complementary metal‐oxide semiconductor (CMOS) processing technology.
Chemoselective Synthesis of N‐arylbenzamides and Benzoyloxyacetanilides from Aryl Isocyanides: Styrene as Aryl and Arylcarboxymethylene Source
Authors: Sharma Poonam , Jain Nidhi 
Published: March 2018

AbstractStyrenes serve as unique aryl or arylcarboxymethylene source towards aryl isocyanides in the presence of Cu(II)/TBHP, and yield N‐arylbenzamides or benzoyloxyacetanilides respectively. The chemoselectivity of the reaction is controlled by the nature of the substituents present on styrene ring. Whereas styrenes substituted with electron‐releasing alkyl and alkoxy groups yield N‐arylbenzamides, unsubstituted styrene and those with electron‐withdrawing substituents furnish benzoyloxyacetanilides as the major product. With benzylamines as the substrate, N‐arylbenzamides are formed exclusively as they act only as an aryl donor. TBHP serves as a promoter and oxygen source. Both the pathways are believed to proceed through an initial oxidative C−C bond cleavage of styrene.magnified image
Palladium‐Catalyzed Enantioselective C−H Olefination of Diaryl Sulfoxides through Parallel Kinetic Resolution and Desymmetrization
Authors: Zhu Yu‐Chao , Li Yan , Zhang Bo‐Chao , Zhang Feng‐Xu , Yang Yi‐Nuo , Wang Xi‐Sheng 
Published: March 2018

AbstractThe first example of PdII‐catalyzed enantioselective C−H olefination with non‐chiral or racemic sulfoxides as directing groups was developed. A variety of chiral diaryl sulfoxides were synthesized with high enantioselectivity (up to 99 %) through both desymmetrization and parallel kinetic resolution (PKR). This is the first report of PdII‐catalyzed enantioselective C(sp2)−H functionalization through PKR, and it represents a novel strategy to construct sulfur chiral centers.
Characterization of an Anthracene Intermediate in Dynemicin Biosynthesis
Authors: Cohen Douglas R. , Townsend Craig A. 
Published: March 2018

AbstractDespite the identification of a β‐hydroxyhexaene produced by the enediyne polyketide synthases (PKSs), the post‐PKS biosynthetic steps to the individual members of this antitumor and antibiotic family remain largely unknown. The massive biosynthetic gene clusters (BGCs) that direct the formation of each product caution that many steps could be required. It was recently demonstrated that the enediyne PKS in the dynemicin A BGC from Micromonospora chersina gives rise to both the anthraquinone and enediyne halves of the molecule. We now present the first evidence for a mid‐pathway intermediate in dynemicin A biosynthesis, an iodoanthracene bearing a fused thiolactone, which was shown to be incorporated selectively into the final product. This unusual precursor reflects just how little is understood about these biosynthetic pathways, yet constrains the mechanisms that can act to achieve the key heterodimerization to the anthraquinone‐containing subclass of enediynes.
Allopurinol Dose Escalation and Mortality Among Patients With Gout
Authors: Coburn Brian W. , Michaud Kaleb , Bergman Debra A. , Mikuls Ted R. 
Published: March 2018

ObjectiveObservational data suggest that hyperuricemia and gout are associated with increased mortality, while allopurinol use is associated with reduced mortality. In addition, the protective effect of allopurinol may be dose dependent. The aim of the current study was to determine whether allopurinol dose escalation is associated with cause‐specific mortality in patients with gout.MethodsIn this 10‐year observational, active‐comparator study of US Veterans with gout who initiated treatment with allopurinol, propensity score matching, Cox proportional hazards models, and competing risks regression analyses were used to assess differences in cause‐specific mortality between patients whose allopurinol dose was escalated (dose escalators) and those whose allopurinol dose was not escalated or was reduced (non‐escalators) over a 2‐year period.ResultsAmong the 6,428 dose escalators and 6,428 matched non‐escalators, there were 2,867 deaths during the observation period (40.4 deaths per 1,000 person‐years). Dose escalators experienced an increase in all‐cause mortality (hazard ratio [HR] 1.08, 95% confidence interval [95% CI] 1.01–1.17), with the effect sizes being similar for incidence of cardiovascular‐related deaths (HR 1.08, 95% CI 0.97–1.21) and cancer‐related deaths (HR 1.06, 95% CI 0.88–1.27), although neither reached statistical significance. Dose escalation to achieve the goal of lowering the serum urate (SU) level to <6.0 mg/dl was infrequent. At 2 years, 10% of dose escalators were receiving a final daily dose of >300 mg and 31% had achieved the SU goal. In a sensitivity analysis limited to dose escalators achieving the SU goal, there was a nonsignificant reduction of 7% in the hazard of cardiovascular‐related mortality (HR 0.93, 95% CI 0.76–1.14).ConclusionThis is the largest study to date to investigate the effects of allopurinol use on mortality and is the first to use a rigorous active‐comparator design. Dose escalation was associated with a small (<10%) increase in all‐cause mortality, thus showing that a strategy of allopurinol dose escalation, which in current real‐life practice is characterized by limited dose increases, is unlikely to improve the survival of patients with gout.
From gene to structure: Lactobacillus bulgaricus D‐lactate dehydrogenase from yogurt as an integrated curriculum model for undergraduate molecular biology and biochemistry laboratory courses
Authors: Lawton Jeffrey A. , Prescott Noelle A. , Lawton Ping X. 
Published: March 2018

AbstractWe have developed an integrated, project‐oriented curriculum for undergraduate molecular biology and biochemistry laboratory courses spanning two semesters that is organized around the ldhA gene from the yogurt‐fermenting bacterium Lactobacillus bulgaricus, which encodes the enzyme d‐lactate dehydrogenase. The molecular biology module, which consists of nine experiments carried out over eleven sessions, begins with the isolation of genomic DNA from L. bulgaricus in yogurt and guides students through the process of cloning the ldhA gene into a prokaryotic expression vector, followed by mRNA isolation and characterization of recombinant gene expression levels using RT‐PCR. The biochemistry module, which consists of nine experiments carried out over eight sessions, begins with overexpression of the cloned ldhA gene and guides students through the process of affinity purification, biochemical characterization of the purified LdhA protein, and analysis of enzyme kinetics using various substrates and an inhibitor, concluding with a guided inquiry investigation of structure‐function relationships in the three‐dimensional structure of LdhA using molecular visualization software. Students conclude by writing a paper describing their work on the project, formatted as a manuscript to be submitted for publication in a scientific journal. Overall, this curriculum, with its emphasis on experiential learning, provides hands‐on training with a variety of common laboratory techniques in molecular biology and biochemistry and builds experience with the process of scientific reasoning, along with reinforcement of essential transferrable skills such as critical thinking, information literacy, and written communication, all within the framework of an extended project having the look and feel of a research experience. © 2018 by The International Union of Biochemistry and Molecular Biology, 46(3):270–278, 2018.
Down‐regulation of the non‐coding RNA H19 and its derived miR‐675 is concomitant with up‐regulation of insulin‐like growth factor receptor type 1 during neural‐like differentiation of human bone marrow mesenchymal stem cells
Authors: Farzi‐Molan Asghar , Babashah Sadegh , Bakhshinejad Babak , Atashi Amir , Fakhr Taha Masoumeh 
Published: March 2018

AbstractThe differentiation of human bone marrow mesenchymal stem cells (BMSCs) into specific lineages offers new opportunities to use the therapeutic efficiency of these pluripotent cells in regenerative medicine. Multiple lines of evidence have revealed that non‐coding RNAs play major roles in the differentiation of BMSCs into neural cells. Here, we applied a cocktail of neural inducing factors (NIFs) to differentiate BMSCs into neural‐like cells. Our data demonstrated that during neurogenic induction, BMSCs obtained a neuron‐like morphology. Also, the results of gene expression analysis by qRT‐PCR showed progressively increasing expression levels of neuron‐specific enolase (NSE) as well as microtubule‐associated protein 2 (MAP‐2) and immunocytochemical staining detected the expression of these neuron‐specific markers along differentiated BMSC bodies and cytoplasmic processes, confirming the differentiation of BMSCs into neuronal lineages. We also compared differences in the expression levels of the long non‐coding RNA (lncRNA) H19 and H19‐derived miR‐675 between undifferentiated and neurally differentiated BMSCs and found that during neural differentiation down‐regulation of the lncRNA H19/miR‐675 axis is concomitant with up‐regulation of insulin‐like growth factor type‐1 (IGF‐1R), a well‐established target of miR‐675 involved in neurogenesis. The findings of the current study provide support for the hypothesis that miR‐675 may confer functionality to H19, suggesting a key role for this miRNA in the neural differentiation of BSMCs. However, further investigation is required to gain deeper insights into the biological roles of this miRNA in the complex process of neurogenesis.