bluuebunny/crossref_metadata_2025 huggingface dataset:
A dialética entre o capital e o Estado no desenvolvimento da rede de transporte aéreo regular no Brasil
Authors: Barros Roberto Hudson
Published: July 2019

O objetivo do presente artigo foi o de analisar alguns aspectos da gestão do ambiente regulatório da aviação civil brasileira, contemplando a transição ocorrida na regulação estatal, que estava a cargo do Departamento de Aviação Civil – DAC, para a Agência Nacional de Aviação Civil – Anac, em 2006, considerada a principal alteração sucedida no setor. O estudo nos levou ainda a identificar um traço marcante da condução dos rumos da aviação civil do país, que foi a presença de uma relação dialética entre o capital e o Estado (com variações de intensidade), durante o período no qual a aviação comercial esteve submetida à autoridade da Aeronáutica, via DAC (entre 1941 e 2006). Com apoio nessa constatação, chegamos à conclusão de que a forma de atuação do Estado brasileiro no âmbito da aviação civil no referido período foi o reflexo do que podemos chamar de um “etos institucional de caráter tutelar”, lastreado num arcabouço regulatório específico que resultou num modelo peculiar de intervenção estatal no setor.

Abstract

THE DIALECTIC BETWEEN CAPITAL AND THE STATE IN THE DEVELOPMENT OF THE REGULAR AIR TRANSPORT NETWORK IN BRAZIL

The purpose of this article was to analyze some aspects of the management of the Brazilian civil aviation regulatory environment, considering the transition occurred in the state regulation, from the Civil Aviation Department - DAC, to the National Civil Aviation Agency - ANAC in 2006, which was considered the main change in the sector. The study also led us to identify a striking feature of the conduction of the civil aviation sector in the country, which was the presence of a dialectic relation between capital and the State (with variations of intensity) during the period in which comercial aviation was ruled by the Air Force authority via DAC (between 1941 and 2006). In support of this finding, we came to the conclusion that the Brazilian State’s role regarding the civil aviation sector in that period was a reflection of what we can call an “institutional ethos of tutelary character”, based on a specific regulatory framework that resulted in a peculiar model of State intervention in the sector.
Classificação do relevo com base nos elementos de Geomorphons e sua relação com a vegetação florestal nativa na Serra do Caverá - Sudoeste do RS, Brasil
Authors: Guadagnin Paula Mirela Almeida , Trentin Romario
Published: July 2019

As formas e a composição do relevo são fatores que contribuem na determinação da ocorrência e dos tipos de vegetação de determinado local. A associação da vegetação com determinados ambientes, em função da insolação recebida, da disponibilidade hídrica, entre outros fatores, está diretamente relacionada à configuração do relevo de uma área. Este trabalho busca demonstrar a relação existente entre a configuração do relevo e a distribuição da vegetação florestal nativa na Serra do Caverá, na região sudoeste do Rio Grande do Sul. A classificação do relevo da área de estudo foi realizada com base nos Geomorphons, a partir do MDE oriundo dos dados SRTM, obtendo-se dez elementos de relevo. Após o mapeamento da vegetação, realizado com base na interpretação de imagens do satélite LANDSAT 8 OLI, foi realizado o cruzamento das informações em ambiente SIG, com o software ArcGis 10.3, ferramenta ArcMap, e também através do cálculo da razão de frequência (Fr). A maior correlação observada foi com os elementos vales e áreas planas (42,52%), seguida da vegetação ocorrente em encostas, bases de encostas e relevos escavados, que juntos somaram 40,85% do total da vegetação florestal da área de estudo.

Abstract

RELIEF CLASSIFICATION BASED ON THE ELEMENTS OF GEOMORPHONS AND THEIR RELATIONS WITH NATIVE FOREST VEGETATION IN THE SERRA DO CAVERÁ - SOUTHWEST OF RS, BRAZIL

The composition and the forms of the relief are factors that contribute in the determination of the occurrence and the types of vegetation of a certain place. The association of vegetation with certain environments due to the sunshine received, water availability, among others, are directly related to the configuration of the relief of an area. The objective of this work is to demonstrate the relations between the configuration of the relief and the distribution of the native forest vegetation in the Serra do Caverá, in the southwest region of Rio Grande do Sul. The relief classification of the study area was based on the Geomorphons, from the DEM generated through the SRTM data, obtaining ten elements. After the vegetation mapping was carried out based on the interpretation of images of the satellite LANDSAT 8 OLI, the information was cross-referenced in a GIS environment, with ArcGis 10.3 software, ArcMap tool, also by calculating the frequency ratio (Fr). The highest correlation observed was with the valleys and flat areas (42.52%), followed by vegetation on hillsides, slope bases and excavated reliefs, which together added up to 40.85% of the total forest vegetation in the study area.
O Uso de Controles Internos: Um Estudo em Empresas Hoteleiras
Authors: Lunkes Rogério João
Published: July 2019

O aumento da competitividade está levando os hotéis a aperfeiçoar seus sistemas de gestão, principalmente, os relacionados à controles internos. É neste sentido que se desenvolve o tema do trabalho: apresentar resultados da utilização de controles internos em empresas hoteleiras. Para tanto, faz-se uma breve revisão sobre os principais conceitos, elementos dos controles internos e uma breve descrição sobre fraudes. Quanto ao delineamento, o trabalho conforma-se como descritivo, sendo conduzido através de instrumento de levantamento (survey) e amostra por acessibilidade. Os resultados obtidos indicam que os hotéis, em geral, utilizam uma quantidade reduzida de controles internos em seu processo de gestão.
Directed in vitro evolution of bacterial expansin BsEXLX1 for higher cellulose binding and its consequences for plant cell wall‐loosening activities
Authors: Hepler Nathan K. , Cosgrove Daniel J.
Published: July 2019

Expansins are cell wall‐loosening proteins found in all land plants and many microbial species. Despite homologous structures, bacterial expansins have much weaker cellulose binding and wall‐loosening activity than plant expansins. We hypothesized stronger cellulose binding would result in greater wall‐loosening activity and used in vitro evolution of Bacillus subtilis BsEXLX1 to test this hypothesis. Mutants with stronger binding generally had greater wall‐loosening activity, but the relationship was nonlinear and plateaued at ~ 40% higher than wild‐type. Mutant E191K exhibited stronger cellulose binding but failed to induce creep, evidently due to protein mistargeting. These results reveal the complexity of interactions between plant cell walls and wall‐modifying proteins, an important consideration when engineering proteins for applications in biofuel production and plant pathogen resistance.
Adaptive control for switched uncertain nonlinear systems with time‐varying output constraint and input saturation
Authors: Chen Aiqing , Tang Li , Liu Yan‐Jun , Gao Ying
Published: July 2019

This paper is concerned with adaptive tracking control for switched uncertain nonlinear systems, which contain the time‐varying output constraint (TVOC) and input asymmetric saturation characteristic. In response to the unknown functions, the fuzzy logic systems are adopted. The controller is constructed by the backstepping technique. Based on the Tangent Barrier Lyapunov Function (BLF‐Tan), an adaptive switched control scheme is designed. It is demonstrated that all signals in the resulted system are semiglobally uniformly ultimately bounded with TVOC under arbitrary switchings. Furthermore, the effectiveness of presented control method is validated via the simulation example.
Cytotoxicity and Corrosion Behavior of Magnesium and Magnesium Alloys in Hank's Solution after Processing by High‐Pressure Torsion
Authors: Lopes Debora R. , Silva Claudio L.P. , Soares Renata B. , Pereira Pedro Henrique R. , Oliveira Ana Celeste , Figueiredo Roberto B. , Langdon Terence G. , Lins Vanessa F.C.
Published: July 2019

It is well‐known that processing by severe plastic deformation using high‐pressure torsion (HPT) promotes grain refinement and increases the strength of magnesium and its alloys. The present research is conducted to evaluate the effect of such processing on cytotoxicity and corrosion behavior in Hank's solution by using samples of commercial purity magnesium and AZ31, AZ91, and ZK60 magnesium alloys. All samples are subjected to electrochemical testing and hydrogen evolution testing before and after processing by HPT and the results show that this processing improves the corrosion resistance of pure magnesium, has no significant effect on the AZ31 and AZ91 alloys but reduces the corrosion resistance of the ZK60 alloy. The observations support the conclusion that grain refinement improves the corrosion resistance of metals with a tendency for passivation but impedes the resistance of metals without passivation. In addition, in vitro cytotoxicity tests are performed on the processed materials and show cell viability in all samples. The results demonstrate that HPT processing may be used to improve the performance of magnesium and its alloys as biodegradable implants.
CoFe–Cl Layered Double Hydroxide: A New Cathode Material for High‐Performance Chloride Ion Batteries
Authors: Yin Qing , Rao Deming , Zhang Guanjun , Zhao Yajun , Han Jingbin , Lin Kun , Zheng Lirong , Zhang Jian , Zhou Jisheng , Wei Min
Published: July 2019

Chloride ion batteries (CIBs) are regarded as promising energy storage systems due to their large theoretical volumetric energy density, high abundance, and low cost of chloride resources. Herein, the synthesis of CoFe layered double hydroxide in the chloride form (CoFe–Cl LDH), for use as a new cathode material for CIBs, is demonstrated for the first time. The CoFe–Cl LDH exhibits a maximum capacity of 239.3 mAh g−1 and a high reversible capacity of ≈160 mAh g−1 over 100 cycles. The superb Cl− ion storage of CoFe–Cl LDH is attributed to its unique topochemical transformation property during the charge/discharge process: a reversible intercalation/deintercalation of Cl− ions in cathode with slight expansion/contraction of basal spacing, accompanied by chemical state changes in Co2+/Co3+ and Fe2+/Fe3+ couples. First‐principles calculations reveal that CoFe–Cl LDH is an excellent Cl− ion conductor, with extremely low energy barriers (0.12−0.25 eV) for Cl− diffusion. This work opens a new avenue for LDH materials as promising cathodes for anion‐type rechargeable batteries, which are regarded as formidable competitors to traditional metal ion‐shuttling batteries.
Experimental Evidence of Large Bandgap Energy in Atomically Thin AlN
Authors: Wang Ping , Wang Tao , Wang Hui , Sun Xiaoxiao , Huang Pu , Sheng Bowen , Rong Xin , Zheng Xiantong , Chen Zhaoying , Wang Yixin , Wang Ding , Liu Huapeng , Liu Fang , Yang Liuyun , Li Duo , Chen Ling , Yang Xuelin , Xu Fujun , Qin Zhixin , Shi Junjie , Yu Tongjun , Ge Weikun , Shen Bo , Wang Xinqiang
Published: July 2019

Ultrathin III‐nitrides beyond BN, such as GaN and AlN, have attracted much research interest due to their potential applications in 2D optoelectronic devices. Taking advantage of the atomic thickness, the bandgap is expected to be widened in these thin films due to quantum confinement. As a promising intrinsic dielectric and tunneling layer for optoelectronic devices, ultrathin freestanding AlN structures have not been systematically studied, and the band structure still remains in the theoretical description. In this work, atomically thin hexagonal AlN nanotubes with controllable wall thickness have been fabricated via selective thermal evaporating the GaN/AlN core/shell nanowires, where the GaN cores entirely decomposed and are removed from the bottom open end while the robust AlN shells remain and form tubular structures. The bandgap energy of 9.2±0.1 eV is confirmed through spectrally resolved X‐ray photoelectron spectroscopy and spatially resolved electron energy loss spectroscopy measurements on AlN nanotubes with the wall thickness of two monolayers.
Semiconductor Quantum Dots: An Emerging Candidate for CO2 Photoreduction
Authors: Wu Hao‐Lin , Li Xu‐Bing , Tung Chen‐Ho , Wu Li‐Zhu
Published: July 2019

As one of the most critical approaches to resolve the energy crisis and environmental concerns, carbon dioxide (CO2) photoreduction into value‐added chemicals and solar fuels (for example, CO, HCOOH, CH3OH, CH4) has attracted more and more attention. In nature, photosynthetic organisms effectively convert CO2 and H2O to carbohydrates and oxygen (O2) using sunlight, which has inspired the development of low‐cost, stable, and effective artificial photocatalysts for CO2 photoreduction. Due to their low cost, facile synthesis, excellent light harvesting, multiple exciton generation, feasible charge‐carrier regulation, and abundant surface sites, semiconductor quantum dots (QDs) have recently been identified as one of the most promising materials for establishing highly efficient artificial photosystems. Recent advances in CO2 photoreduction using semiconductor QDs are highlighted. First, the unique photophysical and structural properties of semiconductor QDs, which enable their versatile applications in solar energy conversion, are analyzed. Recent applications of QDs in photocatalytic CO2 reduction are then introduced in three categories: binary II–VI semiconductor QDs (e.g., CdSe, CdS, and ZnSe), ternary I–III–VI semiconductor QDs (e.g., CuInS2 and CuAlS2), and perovskite‐type QDs (e.g., CsPbBr3, CH3NH3PbBr3, and Cs2AgBiBr6). Finally, the challenges and prospects in solar CO2 reduction with QDs in the future are discussed.
Biohybrid Design Gets Personal: New Materials for Patient‐Specific Therapy
Authors: Raman Ritu , Langer Robert
Published: July 2019

Precision medicine requires materials and devices that can sense and adapt to dynamic physiological and pathological conditions. This motivates the design and manufacture of biohybrid materials that mimic the responsive behaviors demonstrated by natural biological systems. Two parallel approaches to biohybrid design are presented—biomimetics and biointegration. Biohybrid hydrogels that mimic the form and function of natural materials, or that integrate living cells or bioactive moieties, can respond to a range of environmental stimuli in parallel, including heat, light, pH, hydration, enzymes, and electric, mechanical, and magnetic forces. A range of examples that illustrate the tremendous potential of this nascent discipline are presented, and ongoing technical challenges related to manufacturing, storage, transport, and external noninvasive control of these materials that will need to be overcome in the coming years are outlined. The ethical, educational, and regulatory challenges that will govern translation of biohybrid design into medical applications are also discussed. Personalized medical therapies that target the precise needs of patients are a critically needed and expanding market. Biohybrid design offers the unique ability to manufacture materials and devices that match the dynamic and patient‐specific in vivo environment, promising to generate more effective and safe therapies that enable personalized care.
Tandem Reactions of Ynones: via Conjugate Addition of Nitrogen‐, Carbon‐, Oxygen‐, Boron‐, Silicon‐, Phosphorus‐, and Sulfur‐Containing Nucleophiles
Authors: Li Yang , Yu Jian , Bi Yicheng , Yan Guobing , Huang Dayun
Published: July 2019

Ynones are widely used in organic synthesis. Their great success is rooted in their multiple functional groups. This review focus on advance of ynones in published in the decade 2009–2019. Reactions triggered by the conjugate addition of nitrogen‐, carbon‐, oxygen‐, boron‐, silicon‐, phosphorus‐, and sulfur‐containing nucleophiles are thoroughly discussed and summarized herein. Multicomponent reactions, rearrangements, cycloadditions, regio‐ and stereoselective synthesis, oxidations, coupling, green chemistry et al. are depicted in detail. We hope that this review will promote future research in this area.

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Boosting Oxygen Evolution Kinetics by Mn–N–C Motifs with Tunable Spin State for Highly Efficient Solar‐Driven Water Splitting
Authors: Sun Shangcong , Shen Guoqiang , Jiang Jiawei , Mi Wenbo , Liu Xianlong , Pan Lun , Zhang Xiangwen , Zou Ji‐Jun
Published: July 2019

Solar‐driven water splitting is in urgent need for sustainable energy research, for which accelerating oxygen evolution kinetics along with charge migration is the key issue. Herein, Mn3+ within π‐conjugated carbon nitride (C3N4) in form of Mn–N–C motifs is coordinated. The spin state (eg orbital filling) of Mn centers is regulated by controlling the bond strength of Mn–N. It is demonstrated that Mn serves as intrinsic oxygen evolution reaction (OER) site and the kinetics is dependent on its spin state with an optimized eg occupancy of ≈0.95. Specifically, the governing role of eg occupancy originates from the varied binding strength between Mn and OER intermediates. Benefiting from the rapid spin state‐mediated OER kinetics, as well as extended optical absorption (to 600 nm) and accelerated charge separation by intercalated metal‐to‐ligand state, Mn–C3N4 stoichiometrically splits pure water with H2 production rate up to 695.1 µmol g−1 h−1 under simulated sunlight irradiation (AM1.5), and achieves an apparent quantum efficiency of 4.0% at 420 nm, superior to most solid‐state based photocatalysts to date. This work for the first time correlates photocatalytic redox kinetics with the spin state of active sites, and suggests a nexus between photocatalysis and spin theory.
Classification of arthrogryposis
Authors: Hall Judith G. , Kimber Eva , Dieterich Klaus
Published: July 2019

There is a need for a system to classify various forms of arthrogryposis. None is satisfactory or complete. Nevertheless, several have been developed to meet the needs of clinicians, prenatal diagnosticians, researchers, and basic scientists. They all await more insight into basic mechanisms.
Visible Light Mediated External Oxidant Free Selective C5 Bromination of 8‐Aminoquinoline Amides under Ambient Conditions
Authors: Ma Bin , Lu Fangling , Yang Hongmei , Gu Xin , Li Zhen , Li Ru , Pei Hongqiao , Luo Dan , Zhang Heng , Lei Aiwen
Published: July 2019

Selective functionalization of quinolines is the hot topic of organic synthesis due to its wide application in natural products, medicine, etc. In this research, C5 bromination of 8‐aminoquinoline amides have been achieved using the strategy of photoredox catalysis under mild conditions. Easily available 10‐phenylphenothiazine is employed as the organophotoredox catalyst and CBr4 is used as the bromine source. No external oxidant or transition metal catalyst is needed in this transformation. Both the alkyl and aryl substituted carboxamides are compatible with this method.
Ancient DNA and bioarchaeological perspectives on European and African diversity and relationships on the colonial Delaware frontier
Authors: Fleskes Raquel E. , Bruwelheide Karin S. , West Frankie L. , Owsley Douglas W. , Griffith Daniel R. , Barca Kathryn G. , Cabana Graciela S. , Schurr Theodore G.
Published: July 2019

Objectives

Ancient DNA (aDNA) and standard osteological analyses applied to 11 skeletons at a late 17th to early 18th century farmstead site in Delaware to investigate the biological and social factors of settlement and slavery in colonial America.

Materials and methods

Osteological analysis and mitochondrial DNA (mtDNA) sequencing were conducted for all individuals and the resulting data contextualized with archaeological and documentary evidence.

Results

Individuals of European and African descent were spatially separated in this colonial cemetery. The skeletal remains exhibited differences in osteological features and maternal genetic ancestry. A specific mtDNA haplotype appeared in a subset of the European‐descended individuals suggesting they were maternally related. Individuals of African descent were not maternally related, and instead showed a diversity of haplotypes affiliated with present‐day Western, Central, and Eastern regions of Africa.

Discussion

Along with the bioarchaeological and documentary evidence, the aDNA findings contribute to our understanding of life on the colonial Delaware frontier. Evidence of maternal relatedness among European‐descended individuals at the site demonstrates kin‐based settlements in 17th century Delaware and provides preliminary identifications of individuals. The maternal genetic diversity of the individuals with African descent aligns with the routes of the trans‐Atlantic slave trade but broadens our understanding of the ancestries of persons involved in it. Burial positioning, osteological pathology, and lack of maternal kinship among individuals of African descent provide tangible evidence for the emergence of racialized labor and society in Delaware during the late 17th century.
Revision komplexer supramolekularer Polymerisation unter kinetischer und thermodynamischer Kontrolle
Authors: Matern Jonas , Dorca Yeray , Sánchez Luis , Fernández Gustavo
Published: July 2019

Pathway‐Complexity, hierarchische Organisation, Außer‐Equilibrium‐ und metastabile oder kinetisch gefangene Spezies sind Begriffe die in jüngsten, hochqualitativen Publikationen im Feld der supramolekularen Polymere häufig verwendet werden. Oftmals sind die Terminologien, die die verschiedenen Selbstassemblierungspfade, die beteiligten Spezies und deren Beziehung sowie relativen Stabilitäten zueinander beschreiben, nicht trivial. In der Literatur sind häufig verschiedene Begriffe und Klassifizierungen zu finden, in vielen Fällen jedoch ohne klare Definitionen oder Richtlinien wie sie zu benutzen sind oder wie sie experimentell unterschieden werden können. Ziel dieses Kurzaufsatzes ist es, die existierenden Konzepte mithilfe jüngster Literatur zu klassifizieren, differenzieren und zu korrelieren. Dadurch soll der Leser eine generelle Einsicht in thermodynamische und kinetische Aspekte komplexer supramolekularer Polymerisationsprozesse erhalten. Ein gutes Verständnis dieser Begriffe und Konzepte sollte dazu beitragen, neue, komplexe, funktionale Materialien zu erschaffen.
Quantifying the Interdependence of Metal–Ligand Covalency and Bond Distance Using Ligand K‐edge XAS
Authors: Lee Kyounghoon , Blake Anastasia V. , Donahue Courtney M. , Spielvogel Kyle D. , Bellott Brian J. , Daly Scott R.
Published: July 2019

Bond distance is a common structural metric used to assess changes in metal–ligand bonds, but it is not clear how sensitive changes in bond distances are with respect to changes in metal–ligand covalency. Here we report ligand K‐edge XAS studies on Ni and Pd complexes containing different phosphorus(III) ligands. Despite the large number of electronic and structural permutations, P K‐edge pre‐edge peak intensities reveal a remarkable correlation that spectroscopically quantifies the linear interdependence of covalent M−P σ bonding and bond distance. Cl K‐edge studies conducted on many of the same Ni and Pd compounds revealed a poor correlation between M−Cl bond distance and covalency, but a strong correlation was established by analyzing Cl K‐edge data for Ti complexes with a wider range of Ti−Cl bond distances. Together these results establish a quantitative framework to begin making more accurate assessments of metal–ligand covalency using bond distances from readily‐available crystallographic data.
Synergistic effect of CaO and MgO addition on coal ash fusibility in a reducing atmosphere
Authors: Wu Chengli , Xin Yu , Liu Xiang , Li Hanxu , Jiao Facun
Published: July 2019

During coal gasification in entrained‐flow slagging gasifiers, the addition of additives is a promising method to improve coal ash fusibility. In some cases, mixed additives are more effective in decreasing ash fusibility than single additive addition with the same content added. However, mechanisms of mixed additive addition for improving ash melting are scarce. In this study, the effect of CaO, MgO, and their mixtures on the ash flow temperature (FT) of Chinese bituminous coal was investigated. The results show that the single addition of CaO or MgO influenced the ash FT of the test coal sample. The addition of CaO and MgO mixture synergistically decreased the ash FT relative to their single addition. When the ratio of CaO to MgO was 5:5 (mass ratio) in the mixture, the FT decreased to 1297°C, which is 69°C and 110°C lower than that of the single addition of CaO and MgO, respectively. The formation of a low‐temperature eutectic from the interactions between anorthite and olivine caused such synergistic effects.
Thermal and mechanical enhancement of styrene–butadiene rubber by filling with modified anthracite coal
Authors: Tan Jinlong , Cheng Hongzhi , Wei Lubin , Gui Xiahui
Published: July 2019

Anthracite is the highest rank of coal with a layered structure similar to that of graphite. Here, styrene–butadiene rubber/modified anthracite (MA) composites were prepared and analyzed. The microstructure and dispersion of the anthracite were improved by ball milling with the modifier bis‐(γ‐triethoxysilylpropyl)‐tetrasulfide (KH‐Si69). The particle size of the modified coal was decreased significantly to ~3 μm, while surface interactions with the modifier yielded enhanced lamellar morphology and hydrophobic surfaces. The anthracite lamellae were well dispersed in the rubber matrix, providing good reinforcement; the tensile strength of the composite exceeded that of a composite with carbon black (CB) N660 filler (16.65 vs. 14.68 MPa). Moreover, low‐level CB or silica compositing further promoted the dispersion of coal particles in the rubber, effectively enhancing the mechanical reinforcement behavior of the coal particles as well as the thermal stability of the rubber composite. Notably, it led to a 10.63% improvement in tensile strength and a 9.96 °C increase in the 5% mass loss temperature compared to the composite with a single MA filler. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48203.
Two Stable Heterometal‐MOFs as Highly Efficient and Recyclable Catalysts in the CO2 Coupling Reaction with Aziridines
Authors: Kang Xiao‐Min , Yao Lin‐Hong , Jiao Zhuo‐Hao , Zhao Bin
Published: July 2019

Two stable heterometal‐organic frameworks, {Na[LnCo(DATP)2(Ac)(H2O)](NO3)⋅DMA⋅11 H2O}n (Ln=Er(1) and Yb(2)), have been prepared with H2DATP (4′‐(3,5‐dicarboxyphenyl)‐2,2′:6′,2′′′‐terpyridine) as organic building block. These two isostructural compounds featuring two‐dimensional layer architectures possess outstanding thermal stabilities and excellent chemical stabilities in common organic solvents and different acid/base solutions with pH range changing from 1 to 13. Moreover, compounds 1 and 2 serving as heterogeneous catalysts can efficiently catalyse the CO2 fixation reaction with various aziridines to result in corresponding oxazolidinones at 70 °C. Importantly, a good recyclable performance of 1 for at least 10 cycles is observed based on the experimental results, which are further confirmed by PXRD, TGA and ICP analyses.
Impact of El Niño and Southern Oscillation on the summer precipitation over Northwest China
Authors: Lu Bo , Li Haiyan , Wu Jie , Zhang Taixi , Liu Jing , Liu Bao , Chen Ying , Baishan Jiazila
Published: July 2019

Using the reanalysis data and local weather station data, the relationship between El Niño and Southern Oscillation (ENSO) and the summer precipitation over Northwest China (SPNWC) is investigated. A pronounced rainfall response is observed in post‐ENSO summer, especially over North Xinjiang and Yili River valley. A possible mechanism is proposed for such a seasonal lagged impact. El Niño could induce Indian Ocean warming that persists into boreal spring and summer although El Niño itself has dissipated. The warmer Indian Ocean sea surface temperature (SST) would heat the tropospheric atmosphere and elevate the tropical geopotential height at the upper level. As a result, the South Asian High (SAH) exhibits a southward extension due to the increasing geopotential height in its southern flank. A southward displacement of subtropical jet is evident associated with such SAH shift, which further induces a barotropic low pressure anomaly over central Asia. Meanwhile, associated with the southward displacement of subtropical jet, the water vapor from tropical Indian Ocean tends to transport across Iranian Plateau and bring wet and warm air into central Asia. The resultant convergence of water vapor with cold and dry air from high latitude leads to the observed rainfall anomaly to the south and east of Balkhash Lake, explaining the lagged relationship between ENSO and SPNWC. Our results have potential applications on the seasonal prediction of SPNWC.
Lactate: A Novel Signaling Molecule in Synaptic Plasticity and Drug Addiction
Authors: Wang Qiuting , Hu Ying , Wan Jiale , Dong Bo , Sun Jinhao
Published: July 2019

l‐Lactate is emerging as a crucial regulatory nexus for energy metabolism in the brain and signaling transduction in synaptic plasticity, memory processes, and drug addiction instead of being merely a waste by‐product of anaerobic glycolysis. In this review, the role of lactate in various memory processes, synapse plasticity and drug addiction on the basis of recent studies is summarized and discussed. To this end, three main parts are presented: first, lactate as an energy substrate in energy metabolism of the brain is described; second, lactate as a novel signaling molecule in synaptic plasticity, neural circuits, memory, and drug addiction is described; and third, in light of the above descriptions, it is plausible to speculate that lactate is predominantly a signaling molecule in specific memory processes and partly acts as an energy substrate. The future perspective in lactate signaling involving microglia and associated precise signaling pathways in the brain is highlighted.
The Impact of pH on Catalytically Critical Protein Conformational Changes: The Case of the Urease, a Nickel Enzyme
Authors: Mazzei Luca , Cianci Michele , Benini Stefano , Ciurli Stefano
Published: July 2019

Urease uses a cluster of two NiII ions to activate a water molecule for urea hydrolysis. The key to this unsurpassed enzyme is a change in the conformation of a flexible structural motif, the mobile flap, which must be able to move from an open to a closed conformation to stabilize the chelating interaction of urea with the NiII cluster. This conformational change brings the imidazole side chain functionality of a critical histidine residue, αHis323, in close proximity to the site that holds the transition state structure of the reaction, facilitating its evolution to the products. Herein, we describe the influence of the solution pH in modulating the conformation of the mobile flap. High‐resolution crystal structures of urease inhibited in the presence of N‐(n‐butyl)phosphoric triamide (NBPTO) at pH 6.5 and pH 7.5 are described and compared to the analogous structure obtained at pH 7.0. The kinetics of urease in the absence and presence of NBPTO are investigated by a calorimetric assay in the pH 6.0–8.0 range. The results indicate that pH modulates the protonation state of αHis323, which was revealed to have pKa=6.6, and consequently the conformation of the mobile flap. Two additional residues (αAsp224 and αArg339) are shown to be key factors for the conformational change. The role of pH in modulating the catalysis of urea hydrolysis is clarified through the molecular and structural details of the interplay between protein conformation and solution acidity in the paradigmatic case of a metalloenzyme.
Microtubule nucleation in the cytoplasm of developing cortical neurons and its regulation by brain‐derived neurotrophic factor
Authors: Yamada Mimori , Hayashi Kensuke
Published: July 2019

The centrosomes of neurons do not nucleate microtubules (MTs). It is not well known where MTs are nucleated in neurons. We performed MT regrowth experiments in primary cultured cortical neurons from mice. After cold‐nocodazole depolymerization of MTs in neurons at 3 days in vitro (DIV), we observed numerous short MTs that regenerated in the cytoplasm; they were roughly equal in length and randomly oriented. Gamma‐tubulin and MZT2 were detected at one end of these MTs, indicating that the short MTs were nucleated by γ‐tubulin‐ring complexes; the Golgi apparatus was not the origin site of their nucleation. The ratio of MT‐regenerating cells, the density of regenerated MTs, and their lengths decreased at 7 DIV. Pretreatment of neurons with protein‐kinase inhibitors, K‐252a, staurosporine, or H7 diminished the length of the regenerated MTs, while pretreatment of neurons with brain‐derived neurotrophic factor increased the length of regenerated MTs. These results support the idea that short MTs with mixed orientations are transiently generated in the cytoplasm of differentiating neurons, and that they are possibly transported into dendrites to provide seeds for MTs with mixed polarity.
Chemical Bonding from the Statistics of the Electron Distribution
Authors: Pendás Ángel Martín , Francisco Evelio
Published: July 2019

An introduction to the theory of chemical bonding from the point of view of the statistics of the electron distribution is presented. When atoms bind to form a molecule, their originally fixed number of electrons ceases to be a well‐defined observable, and this implies that their in‐the‐molecule electron populations fluctuate. If a chemically meaningful definition of an atom in a molecule is assumed, the probabilities of finding a given number of electrons in each of the atoms comprising the molecule can be computed. We show in this review how the complete electron distribution function (EDF) can be used to reconstruct the basic concepts and quantities used in chemical bonding without recourse to the orbital paradigm. From the statistical point of view, which inherits Born's probabilistic interpretation of quantum mechanics, a set of atoms are bonded when their electron populations are mutually dependent. We quantify this statistical dependence by the cumulant moments of the EDF, which provide a consistent description of both two‐ and multi‐center bonding. Particular attention is paid to building EDFs from model wavefunctions. With this, a simple bridge with orbital thinking is built. The statistical interpretation allows to easily classify all possible bonds of a given kind. We show that there are vast unexplored territories that should receive due consideration. Although building EDFs from models is easy and very instructive, the contrary is considerably more difficult. Recipes to extract chemical information from computed EDFs are also reviewed and, in all the cases, simple toy systems are used to show how the methodology works, allowing non‐experts to follow easily the presentation.
Iron–PNP‐Pincer‐Catalyzed Transfer Dehydrogenation of Secondary Alcohols
Authors: Budweg Svenja , Wei Zhihong , Jiao Haijun , Junge Kathrin , Beller Matthias
Published: July 2019

Invited for this month's cover is the group of Matthias Beller at the Leibniz‐Institute for Catalysis in Rostock. The image illustrates the catalytic dehydrogenation of secondary alcohols to the corresponding ketones using iron‐based pincer complexes. The Communication itself is available at 10.1002/cssc.201900308.
The environmental and genetic determinants of chick telomere length in Tree Swallows (Tachycineta bicolor)
Authors: Belmaker Amos , Hallinger Kelly K. , Glynn Rebbeca A. , Winkler David W. , Haussmann Mark F.
Published: July 2019

Conditions during early life can have dramatic effects on adult characteristics and fitness. However, we still know little about the mechanisms that mediate these relationships. Telomere shortening is one possibility. Telomeres are long sequences of DNA that protect the ends of chromosomes. They shorten naturally throughout an individual's life, and individuals with short telomeres tend to have poorer health and reduced survival. Given this connection between telomere length (TL) and fitness, natural selection should favor individuals that are able to retain longer telomeres for a greater portion of their lives. However, the ability of natural selection to act on TL depends on the extent to which genetic and environmental factors influence TL. In this study, we experimentally enlarged broods of Tree Swallows (Tachycineta bicolor) to test the effects of demanding early‐life conditions on TL, while simultaneously cross‐fostering chicks to estimate heritable genetic influences on TL. In addition, we estimated the effects of parental age and chick sex on chick TL. We found that TL is highly heritable in Tree Swallow chicks, and that the maternal genetic basis for TL is stronger than is the paternal genetic basis. In contrast, the experimental manipulation of brood size had only a weak effect on chick TL, suggesting that the role of environmental factors in influencing TL early in life is limited. There was no effect of chick sex or parental age on chick TL. While these results are consistent with those reported in some studies, they are in conflict with others. These disparate conclusions might be attributable to the inherent complexity of telomere dynamics playing out differently in different populations or to study‐specific variation in the age at which subjects were measured.
Filling the “data gap”: Using paleoecology to investigate the decline of Najas flexilis (a rare aquatic plant)
Authors: Bishop Isabel J. , Bennion Helen , Sayer Carl D. , Patmore Ian R. , Yang Handong
Published: July 2019

In the absence of long‐term monitoring records, paleoecology can be used to extend knowledge of species and community ecology into the past. The rare and declining aquatic plant Najas flexilis is a priority species for conservation across Europe, and is an ideal candidate for paleoecological study; not only are historical records of the plant sparse, but its seeds are commonly found and well preserved in lake sediment cores. In this study, we investigate the timing and causes of decline at two UK sites at which N. flexilis has recently become extinct: Esthwaite Water (England) and Loch of Craiglush (Scotland). For both sites, multiple paleoecological indicators and available historical biological records and monitoring data are compared to numbers of N. flexilis seeds enumerated in dated sediment cores representing the last 150 years. At Esthwaite Water, N. flexilis seeds were found in abundance in association with indicators of a clear, oligo‐mesotrophic, mildly alkaline lake. Eutrophication led to the disappearance of N. flexilis in the 1980s. By contrast, far fewer N. flexilis seeds were found in a core from Loch of Craiglush, and the current period of N. flexilis absence was found to be one of several over the last 100 years. Species represented in cores taken from Loch of Craiglush were indicative of slightly more acidic conditions than Esthwaite Water. Given that N. flexilis favours circumneutral to alkaline conditions, it is possible that Loch of Craiglush has not always been favourable for the plant. These findings have important implications for future conservation efforts, particularly at Esthwaite Water where they suggest that recent failed attempts to reintroduce the species may have been premature. More generally, this study demonstrates the value of paleoecological techniques as a means to provide the long‐term context that is often missing from conservation planning and management.
Noninvasive Tests Accurately Identify Advanced Fibrosis due to NASH: Baseline Data From the STELLAR Trials
Authors: Anstee Quentin M. , Lawitz Eric J. , Alkhouri Naim , Wong Vincent Wai‐Sun , Romero‐Gomez Manuel , Okanoue Takeshi , Trauner Michael , Kersey Kathryn , Li Georgia , Han Ling , Jia Catherine , Wang Lulu , Chen Guang , Subramanian G. Mani , Myers Robert P. , Djedjos C. Stephen , Kohli Anita , Bzowej Natalie , Younes Ziad , Sarin Shiv , Shiffman Mitchell L. , Harrison Stephen A. , Afdhal Nezam H. , Goodman Zachary , Younossi Zobair M.
Published: July 2019

Accurate noninvasive tests (NITs) are needed to replace liver biopsy for identifying advanced fibrosis caused by nonalcoholic steatohepatitis (NASH). We analyzed screening data from two phase 3 trials of selonsertib to assess the ability of NITs to discriminate advanced fibrosis. Centrally read biopsies from the STELLAR studies, which enrolled patients with bridging fibrosis and compensated cirrhosis, were staged according to the NASH Clinical Research Network classification. We explored associations between fibrosis stage and NITs, including the nonalcoholic fatty liver disease fibrosis score (NFS), fibrosis‐4 (FIB‐4) index, Enhanced Liver Fibrosis (ELF) test, and liver stiffness by vibration‐controlled transient elastography (LS by VCTE). The performance of these tests to discriminate advanced fibrosis, either alone or in combinations, was evaluated using areas under the receiver operating characteristic curve (AUROCs) with 5‐fold cross‐validation repeated 100 times. Of the 4,404 patients screened for these trials, 3,202 had evaluable biopsy data: 940 with F0‐F2 fibrosis and 2,262 with F3‐F4 fibrosis. Significant differences between median values of NITs for patients with F0‐F2 versus F3‐F4 fibrosis were observed: −0.972 versus 0.318 for NFS, 1.18 versus 2.20 for FIB‐4, 9.22 versus 10.39 for ELF, and 8.8 versus 16.5 kPa for LS by VCTE (all P < 0.001). AUROCs ranged from 0.75 to 0.80 to discriminate advanced fibrosis. FIB‐4 followed by an LS by VCTE or ELF test in those with indeterminate values (FIB‐4 between 1.3 and 2.67) maintained an acceptable performance while reducing the rate of indeterminate results. Conclusion: Among patients being considered for enrollment into clinical trials, NITs alone or in combination can reduce the need for liver biopsy to discriminate advanced fibrosis caused by NASH. The predictive value of these tests for general screening will require confirmation in a real‐world population.
Analyzing inappropriate magnetic resonance imaging (MRI) prescriptions and resulting economic burden on patients suffering from back pain
Authors: Jahanmehr Nader , Bigdeli Atieh Sadat , Salari Hedayat , Mokarami Hussein , KhodaKarim Soheila , Damiri Soheila
Published: July 2019

Introduction

Back pain is a common global disorder and magnetic resonance imaging (MRI) is one method of assessing its cause. The lack of official and general clinical guidelines is the cause of inadequate supervision of lumbar MRI prescriptions. The goal of this research was to analyze inappropriate lumbar MRI prescriptions and the resulting economic burden on individuals.

Method

This is a descriptive‐analytical study carried out on a sample of 614 patients who visited four hospitals in Tehran. The appropriateness or inappropriateness of the MRI prescriptions was determined using clinical guidelines and a questionnaire based on previous studies. The economic burden created by inappropriate prescriptions for MRIs was determined after calculating the total direct and indirect costs.

Findings

The total MRI prescription cost paid by the study sample was $26 071, and the cost of inappropriate prescriptions was $10 310. The MRI prescription rate had a significant relationship with gender, age, education, employment, primary insurance type, and supplemental health insurance.

Conclusion

The research findings revealed relatively high rates of inappropriate MRI prescriptions in the private and public sectors. Hence, policymakers should design, create, and develop clinical guidelines and enforce the policies and rules to decrease inappropriate MRI prescriptions.
Adverse events in Malaysia: Associations with nurse's ethnicity and experience, hospital size, accreditation, and teaching status
Authors: Jarrar Mu'taman , Al‐Bsheish Mohammad , Dardas Latefa Ali , Meri Ahmed , Sobri Minai Mohd
Published: July 2019

Purpose

In Malaysia, private healthcare sector has become a major player in delivering healthcare services alongside the government healthcare sector. However, wide disparities in health outcomes have been recorded, and adverse events in these contexts have yet to be explored. The purpose of this study was to explore associations between nurse's ethnicity and experience, hospital size, accreditation, and teaching status with adverse events in Malaysian private hospitals.

Methods

A cross‐sectional survey was conducted in 12 private hospitals in Malaysia. A total of 652 (response rate = 61.8%) nurses participated in the study. Data were collected using self‐administered questionnaire on nurses' characteristic, adverse events and events reporting, and perceived patient safety.

Results

Patient and family complaints events were the most common adverse events in Malaysian private hospitals as result of increased cost of care (3.24 ± 0.95) and verbal miscommunication (3.52 ± 0.87).

Conclusion

Hospital size, accreditation status, teaching status, and nurse ethnicity had a mixed effect on patient safety, perceived adverse events, and events reporting. Policy makers can benefit that errors are related to several human and system related factors. Several system reforms and multidisciplinary efforts were recommended for optimizing health, healthcare and preventing patient harm.
Patients' choice and preference for common disease diagnosis and diabetes care: A discrete choice experiment
Authors: Zhu Jingrong , Li Jinlin , Zhang Zengbo , Li Hao
Published: July 2019

Objective

To examine the impact of policy incentives on patient's choice of health‐care providers for primary care and to capture the preferences for general practitioner (GP) care.

Study design

Discrete choice experiment.

Methods

A random sample of 704 adults and of 181 diabetics were independently surveyed to elicit patients' preferences for common disease diagnosis and diabetes care. Mixed logit regression was used for the analysis.

Results

On average, the most valued attribute in GP care are the organizational factors related to whether the provider has sufficient medicine and equipment to provide capable primary care service. Policy incentives, such as reducing waiting time, providing prior expert access, and increasing Medicare reimbursement, can facilitate the utilization of the GP system. Significant preference heterogeneity was identified; specifically, patient preferences significantly differ with regard to demand for common disease diagnosis and diabetes care.

Conclusion

The identification of the preferences of specific groups in regard to GP care is an organizational and political imperative. Policy incentives are useful tools to guide patients' health care seeking behavior. To change the perceptions of Chinese patients with regard to health care, policy makers should consider the heterogeneous responses of residents to policy incentives and focus their efforts on key cohorts.