bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular characterization of clonal lineage and staphylococcal toxin genes fromS. aureusin Southern Nigeria
Authors: Ayeni Funmilola A. , Ruppitsch Werner , Allerberger Franz
Published: July 2018

Background

Staphylococcus aureusis a human colonizer with high potential for virulence, and the spread of the virulent strains from the colonized hosts to non-carriers in the community is on the increase. However, there are few reports on comprehensive analysis of staphylococcal enterotoxin (SE) genes with clonal lineage inS. aureusin Africa. This is essential because of diversity of cultures and habits of the people. This study analyzed spa types and enterotoxin genes inS. aureusstrains previously isolated from the human nostrils, poultry and clinical samples in Southern Nigeria.

Methods

Forty-sevenS. aureusisolates were obtained from humans nostrils (n = 13), clinical strains (n = 21) and poultry (n = 13) from previous studies in Southern Nigeria. The strains were analyzed formecAgene, selected toxins genes (sea, seb, sec, sed, see, seg, seh, sei, sej, sek, sel, sem, sen, seo, sep, seq, ser, seu)and Panton-Valentine leukocidin (PVL) gene(lukS-PV/lukF-PV)by PCR. Population structures of the strains were detected by Staphylococcal protein A (spa) typing.

Results

Twenty different spa types were obtained with the highest percentages, 17% observed inspatype t091 from clinical, nasal and poultry samples while t069 was the most prevalent spa type in poultry. Two MRSA were only detected in human strains. The poultry strains had the highest occurrence of SE genes (18%) followed by nasal strains (15%) and clinical strains (10%). Eighty-nine percent of all tested isolates harbored at least one SE gene;seowas the most prevalent (34%) followed byseg(30%) andsea(21%), whilesec, seeandsejwere absent in all strains. Spa type t355 was associated withlukS-PV/lukF-PVgene and complete absence of all studied SE.Sea, seq, seb, sekwere associated with spa type t069;seawas associated with t127 whilesepwas associated with spa type t091. There were coexistences ofseo/segandsei/seg.

Conclusions

The higher carriage of staphylococci enterotoxin genes by the nasal and poultryS. aureusstrains suggests a high potential of spread of staphylococcal food poisoning through poultry and healthy carriers in the community. This is the first report of high occurrence of staphylococcal enterotoxins genes in poultry from Nigeria.
Associação entre esclerose múltipla e alelos hla-drb1* em uma população miscigenada de Salvador, Ba, Brasil
Authors: Sacramento Thaiana De Oliveira , Lemaire Denise Carneiro
Published: July 2018

Introdução: a esclerose múltipla é uma doença que afeta preferencialmente o sistema nervoso central de mulheres jovens, causando-lhes graus variáveis de incapacidades física e cognitiva. Etiologicamente associa fatores ambientais, biológicos, sócio-econômicos e genéticos, como por exemplo genes do MHC classe II, especialmente os alelos HLA-DRB1*. Objetivo: determinar a frequência dos alelos HLA DRB1* em portadores de esclerose múltipla atendidos no centro de referência do C.H.U.P.E.S, UFBA, no período de outubro de 2014 a abril de 2015 e associá-las a variáveis clínico-demográficas. Metodologia: estudo do tipo caso-controle, aprovado pelo comitê de ética da Faculdade de medicina da Universidade Federal da Bahia (CAAE: 3517134.0.0000.5577), que envolveu uma amostra de conveniência composta por 97 indivíduos, cujos dados clínico-demográficos foram coletados através de questionário desenvolvido para a pesquisa. A genotipagem dos alelos HLA-DRB1* foi realizada através da técnica “HLA-DR SSO GenotypingTest”. Resultados: a análise quantitativa revelou perfil genotípico do tipo HLA-DRB1*15 (20,5%), em mulheres (83,0%), das raças/etnias negra ou parda (75,0%), com faixa etária entre 30 e 39 anos (28,0%). Houve predomínio da forma clínica surtoremissiva da doença (76,0%), dentre os doentes com idade mais avançada (55,0%), sem permanência de sequela clínica (70,0%) e que usavam algum tipo de Interferon (58,0%). A análise qualitativa indicou maiores frequências, na forma progressiva de esclerose múltipla dos grupos alélicos HLA-DRB1*12 (22,0%), e dos alelos HLA-DRB1*13 (12,6%)e HLA-DRB1*15 (22,0%) naqueles indivíduos com a forma surtoremissiva. Negros e pardos demonstraram maior prevalência do alelo HLA-DRB1*15 (24,0%), enquanto que nos brancos houve maior prevalência do alelo HLA-DRB1*07 (20,0%). Conclusão: forte associação entre as frequências alélicas, esclerose múltipla e as variáveis raça/etnia e forma clínica da doença.
Fostering learning from instructional video in a second language
Authors: Lee Hyunjeong , Mayer Richard E.
Published: July 2018

This study investigated the most effective way to present an instructional video that contains words in the students' second language. Korean‐speaking university students received a 16‐min video lesson on Antarctica that included English narration (video + narration group), English text subtitles (video + text group), or English narration with simultaneous text subtitles (video + narration + text group). On a comprehension test, the video + text group scored higher than each of the other two groups, in contrast to the modality effect; and the video + narration + text group outscored the video + narration group, in contrast to the redundancy effect. Each of the lessons that included text was rated as less difficult than the lesson with narration only. The narration + text group reported lower effort than each of the other groups. Results highlight boundary conditions for two principles of multimedia instructional design that apply for college students who are learning in a second language. Theoretical implications are discussed.
The Effect of Solid Solute and Precipitate Phase on Young's Modulus of Binary Mg–RE Alloys
Authors: Xu Yu‐Ling , Wang Li , Huang Meng , Gensch Felix , Kainer Karl Ulrich , Hort Norbert
Published: July 2018

The Young's modulus for a series of binary Mg–Gd and Mg–Nd alloys are studied in the present work. Fine and homogeneous grain structures are prepared by using hot extrusion. The results demonstrate that the Young's modulus of Mg–Gd alloys increase linearly by the increase of Gd in solid solution. Aging treatments are applied to the Mg–0.79–2.43 at% Gd alloys. A needle‐like orthorhombic structureβ′ phase is formed in Mg matrix. Due to a higher Young's modulus of the intermetallicβ′ phase which is estimated to be 80 GPa, the Young's modulus of Mg–Gd alloys are enhanced by aging. The results for Mg–Nd alloys indicate that Young's modulus firstly decreases and reaches 42.53 GPa for Mg–0.18 at% Nd which is attributed to the solid solution of Nd in Mg. The Mg41Nd5particles appear in Mg matrix when Nd content is higher than 0.18 at%, and Young's modulus of the particles is tested as 57.0 GPa. Thus, the Young's modulus increases to 43.42 GPa for Mg–0.63 at% Nd. The Young's modulus of Mg alloys are affected by altering the crystal cell parameters with solid solutes, and/or the formation of precipitate phases with varying amounts.
The Influence of Sintering Parameters in the Microstructure and Mechanical Properties of a Cu–Al–Ni–Mn–Zr Shape Memory Alloy
Authors: Gera Dennis B. , Soyama Juliano , Cava Régis D. , Spinelli José E. , Kiminami Claudio S.
Published: July 2018

Shape memory alloys from the Cu–Al–Ni system arouse interest for industrial applications due to their high thermal stability and low cost. In this study, the Cu–11.8Al–3.2Ni–3Mn–0.5Zr alloy is prepared through a powder metallurgy processing technique. Specimens are produced by a conventional uniaxial press followed by sintering procedure under argon atmosphere. The sintering temperature is varied in the range from 950 to 1060 °C, whereas sintering time is varied from 0.5 to 2 h. The results denote that a temperature close to the alloy's solidus temperature is necessary to achieve higher densities. Moreover, martensite‐type microstructures are observed, despite the slow cooling rate applied after sintering. The compression strengths are in the order of 500 MPa with the exception of the specimens sintered for 1.5 h, which reaches an average of 700 MPa. This is explained by the lower porosity resulting from liquid phase sintering. The forward and reverse martensitic transformation temperatures, however, are quite similar for all examined conditions.
Plasmonic Au/TiO2‐Dumbbell‐On‐Film Nanocavities for High‐Efficiency Hot‐Carrier Generation and Extraction
Authors: Ho Kwun Hei Willis , Shang Aixue , Shi Fenghua , Lo Tsz Wing , Yeung Pui Hong , Yu Yat Sing , Zhang Xuming , Wong Kwok‐yin , Lei Dang Yuan
Published: July 2018

Plasmon‐induced hot carriers have vast potential for light‐triggered high‐efficiency carrier generation and extraction, which can overcome the optical band gap limit of conventional semiconductor‐based optoelectronic devices. Here, it is demonstrated that Au/TiO2 dumbbell nanostructures assembled on a thin Au film serve as an efficient optical absorber and a hot‐carrier generator in the visible region. Upon excitation of localized surface plasmons in such coupled particle‐on‐film nanocavities, the energetic conduction electrons in Au can be injected over the Au/TiO2 Schottky barrier and migrated to TiO2, participating in the chemical reaction occurring at the TiO2 surface. Compared with the same dumbbell nanostructures on an indium tin oxide (ITO) film, such nanocavities exhibit remarkable enhancement in both photocurrent amplitude and reaction rate that arise from increased light absorption and near‐field amplification in the presence of the Au film. The incident‐wavelength‐dependent photocurrent and reaction rate measurements jointly reveal that Au‐film‐mediated near‐field localization facilitates more efficient electron–hole separation and transport in the dumbbells and also promotes strong d‐band optical transitions in the Au film for generation of extra hot electrons. Such nanocavities provide a new plasmonic platform for effective photoexcitation and extraction of hot carriers and also better understanding of their fundamental science and technological implications in solar energy harvesting.
Magnetically Recyclable Catalytic Carbon Nanoreactors
Authors: Aygün Mehtap , Chamberlain Thomas W. , Gimenez‐Lopez Maria del Carmen , Khlobystov Andrei N.
Published: July 2018

Multifunctional nanoreactors are assembled using hollow graphitized carbon nanofibers (GNFs) combined with nanocatalysts (Pd or Pt) and magnetic nanoparticles. The latter are introduced in the form of carbon‐coated cobalt nanomagnets (Co@Cn) adsorbed on GNF, or formed directly on GNF from ferrocene yielding carbon‐coated iron nanomagnets (Fe@Cn). High‐resolution transmission electron microscopy demonstrates that Co@Cn and Fe@Cn are attached effectively to the GNFs, and the loading of nanomagnets required for separation of the nanoreactors from the solution with an external magnetic field is determined using UV–vis spectroscopy. Magnetically functionalized GNFs combined with palladium or platinum nanoparticles result in catalytically active magnetically separable nanoreactors. Applied to the reduction of nitrobenzene the multifunctional nanoreactors demonstrate high activity and excellent durability, while their magnetic recovery enables significant improvement in the reuse of the nanocatalyst over five reaction cycles (catalyst loss < 0.5 wt%) as compared to the catalyst recovery by filtration (catalyst loss <10 wt%).
Dirac Semimetal Heterostructures: 3D Cd3As2 on 2D Graphene
Authors: Wu Yan‐Fei , Zhang Liang , Li Cai‐Zhen , Zhang Zhen‐Sheng , Liu Song , Liao Zhi‐Min , Yu Dapeng
Published: July 2018

Dirac semimetal is an emerging class of quantum matters, ranging from 2D category, such as, graphene and surface states of topological insulator to 3D category, for instance, Cd3As2 and Na3Bi. As 3D Dirac semimetals typically possess Fermi‐arc surface states, the 2D–3D Dirac van der Waals heterostructures should be promising for future electronics. Here, graphene–Cd3As2 heterostructures are fabricated through direct layer‐by‐layer stacking. The electronic coupling results in a notable interlayer charge transfer, which enables us to modulate the Fermi level of graphene through Cd3As2. A planar graphene p–n–p junction is achieved by selective modification, which demonstrates quantized conductance plateaus. Moreover, compared with the bare graphene device, the graphene–Cd3As2 hybrid device presents large nonlocal signals near the Dirac point due to the charge transfer from the spin‐polarized surface states in the adjacent Cd3As2. The results enrich the family of van der Waals heterostructure and should inspire more studies on the application of Dirac/Weyl semimetals in spintronics.
Boron Embedded in Metal Iron Matrix as a Novel Anode Material of Excellent Performance
Authors: Dong Wujie , Zhao Yantao , Wang Xin , Yuan Xiaotao , Bu Kejun , Dong Chenlong , Wang Ruiqi , Huang Fuqiang
Published: July 2018

Boron, the most ideal lithium‐ion battery anode material, demonstrates highest theoretical capacity up to 12 395 mA h g−1 when forming Li5B. Furthermore, it also exhibits promising features such as light weight, considerable reserves, low cost, and nontoxicity. However, boron‐based materials are not in the hotspot list because Li5B may only exist when B is in atomically isolated/dispersed form, while the aggregate material can barely be activated to store/release Li. At this time, an ingenious design is demonstrated to activate the inert B to a high specific capacity anode material by dispersing it in a Fe matrix. The above material can be obtained after an electrochemical activation of the precursors Fe2B/Fe and B2O3/Fe. The latter harvests the admirable capacity, ultrahigh tap density of 2.12 g cm−3, excellent cycling stability of 3180 mA h cm−3 at 0.1 A g−1 (1500 mA h g−1) after 250 cycles, and superlative rate capability of 2650 mA h cm−3 at 0.5 A g−1, 2544 mA h cm−3 at 1.0 A g−1, and 1696 mA h cm−3 at 2.0 A g−1. Highly conductive matrix promoted reversible Li storage of boron‐based materials might open a new gate for advanced anode materials.
Ultrasound Promoted Step‐Growth Polymerization and Polymer Crosslinking Via Copper Catalyzed Azide–Alkyne “Click” Reaction
Authors: Mohapatra Hemakesh , Ayarza Jorge , Sanders Emily C. , Scheuermann Angelique M. , Griffin Philip J. , Esser‐Kahn Aaron P.
Published: July 2018

Mechano‐activated chemistry is a powerful tool for remodeling of synthetic polymeric materials, however, few reactions are currently available. Here we show that using piezochemical reduction of a CuII‐based pre‐catalyst, a step‐growth polymerization occurs via the copper catalyzed azide–alkyne cycloaddition (CuAAC) reaction to form a linear polytriazole. Furthermore, we show that a linear polymer can be crosslinked mechanochemically using the same chemistry to form a solid organogel. We envision that this chemistry can be used to harness mechanical energy for constructive purposes in polymeric materials.
Regiodivergent Copper Catalyzed Borocyanation of 1,3‐Dienes
Authors: Jia Tao , He Qiong , Ruscoe Rebecca E. , Pulis Alexander P. , Procter David J.
Published: July 2018

Copper catalyzed multi‐functionalization of unsaturated carbon‐carbon bonds is a powerful tool for the generation of complex molecules. We report a regiodivergent process that allows a switch between 1,4‐borocupration and 4,1‐borocupration of 1,3‐dienes upon a simple change in ligand. The subsequently generated allyl coppers are trapped in an electrophilic cyanation to selectively generate densely functionalized and synthetically versatile 1,2‐ or 4,3‐borocyanation products.
Metal‐Free Direct C−H Cyanation of Alkenes
Authors: Wang Xi , Studer Armido
Published: July 2018

A metal‐free and direct alkene C−H cyanation is described. Directing groups are not required and the mechanism involves electrophilic activation of the alkene by a cyano iodine(III) species generated in situ from a [bis(trifluoroacetoxy)iodo]arene and trimethylsilyl cyanide as the cyanide source. This C−H functionalization can be conducted on gram scale, and for noncyclic 1,1‐ and 1,2‐disubstuted alkenes high stereoselectivity is achieved, thus rendering the method highly valuable.
A Fully Automated Continuous‐Flow Platform for Fluorescence Quenching Studies and Stern–Volmer Analysis
Authors: Kuijpers Koen P. L. , Bottecchia Cecilia , Cambié Dario , Drummen Koen , König Niels J. , Noël Timothy
Published: July 2018

Herein, we report the first fully automated continuous‐flow platform for fluorescence quenching studies and Stern–Volmer analysis. All the components of the platform were automated and controlled by a self‐written Python script. A user‐friendly software allows even inexperienced operators to perform automated screening of novel quenchers or Stern–Volmer analysis, thus accelerating and facilitating both reaction discovery and mechanistic studies. The operational simplicity of our system affords a time and labor reduction over batch methods while increasing the accuracy and reproducibility of the data produced. Finally, the applicability of our platform is elucidated through relevant case studies.
Surprising Antibacterial Activity and Selectivity of Hydrophilic Polyphosphoniums Featuring Sugar and Hydroxy Substituents
Authors: Cuthbert Tyler J. , Hisey Benjamin , Harrison Tristan D. , Trant John F. , Gillies Elizabeth R. , Ragogna Paul J.
Published: July 2018

There is currently an urgent need for the development of new antibacterial agents to combat the spread of antibiotic‐resistant bacteria. We explored the synthesis and antibacterial activities of novel, sugar‐functionalized phosphonium polymers. While these compounds exhibited antibacterial activity, we unexpectedly found that the control polymer poly(tris(hydroxypropyl)vinylbenzylphosphonium chloride) showed very high activity against both Gram‐negative Escherichia coli and Gram‐positive Staphylococcus aureus and very low haemolytic activity against red blood cells. These results challenge the conventional wisdom in the field that lipophilic alkyl substituents are required for high antibacterial activity and opens prospects for new classes of antibacterial polymers.
Randomized clinical trial of stapler hepatectomy versus LigaSure™ transection in elective hepatic resection
Authors: Fritzmann J , Kirchberg J , Sturm D , Ulrich A B , Knebel P , Mehrabi A , Büchler M W , Weitz J , Reissfelder C , Rahbari N N
Published: July 2018

Background

Previous studies have demonstrated stapler hepatectomy and use of various energy devices to be safe alternatives to the clamp-crushing technique in elective hepatic resection. In this randomized trial, the effectiveness and safety of stapler hepatectomy were compared with those of parenchymal transection with the LigaSure™ vessel sealing system.

Method

Patients scheduled for elective liver resection at two tertiary-care centres were randomized during surgery to stapler hepatectomy or transection with the LigaSure™ device. Total intraoperative blood loss was the primary efficacy endpoint. Transection time, duration of operation, perioperative complications and length of hospital stay were recorded as secondary endpoints.

Results

A total of 138 patients were analysed, 69 in the LigaSure™ and 69 in the stapler hepatectomy group. Baseline characteristics were well balanced between the groups. Mean intraoperative blood loss was significantly higher in the LigaSure™ group than the stapler hepatectomy group: 1101 (95 per cent c.i. 915 to 1287) versus 961 (752 to 1170) ml (P = 0·028). The parenchymal transection time was significantly shorter in the stapler group (P = 0·005), as was the total duration of operation (P = 0·027). Surgical morbidity did not differ between the groups, nor did the grade of complications.

Conclusion

Stapler hepatectomy was associated with reduced blood loss and a shorter duration of operation than the LigaSure™ device for parenchymal transection in elective partial hepatectomy. Registration number: NCT01858987 (http://www.clinicaltrials.gov).
How do integrated quality and environmental management practices affect firm performance? Mediating roles of quality performance and environmental proactivity
Authors: Arda Ozlem Ayaz , Bayraktar Erkan , Tatoglu Ekrem
Published: July 2018

Based on a sample of 208 Turkish firms, this paper investigates the integration of two management systems, quality management and environmental management, and explores the effect of this integration on firm performance. First, a conceptual framework was developed, relying on the premises of the resource‐based view. Second, mediating roles of quality performance and environmental proactivity were examined on the association between integrated quality and environmental management systems and firm performance. Among the underlying trends, both quality performance and environmental proactivity were found to fully mediate the relationship between integrated quality and environmental management and firm performance.
Examining the drivers and outcomes of corporate commitment to climate change action in European high emitting industry
Authors: Littlewood David , Decelis Rachel , Hillenbrand Carola , Holt Diane
Published: July 2018

Climate change is a major strategic issue for firms that also has global environmental, social and economic implications. This paper draws upon quantitative survey research to examine the drivers and outcomes of corporate commitment to climate change action in European high emitting industry. More specifically, this research examines the significance of business drivers, sustainability drivers, and stakeholder pressure, in motivating corporate commitment to climate change action in such industry. It furthermore assesses relationships between commitment and actual corporate greenhouse gas (GHG) performance. It is found that in European high emitting industry, business drivers and stakeholder pressure, but not sustainability drivers, enhance corporate commitment to climate change action, and that higher commitment leads to improved GHG performance. This paper contributes to hitherto limited empirical work on the drivers and outcomes of corporate commitment to climate change action, particularly in European industry contexts. It also contributes to advancing methodology in the field.
RadioEarth: An educational software tool based on Google Earth for radioelectric coverage analysis
Authors: Juan‐Llacer Leandro , Rodriguez José‐Víctor , Molina‐Garcia‐Pardo José‐María , Pascual‐García Juan , Martínez‐Inglés Mayte
Published: July 2018

The expansion of wireless communication systems (GSM, UMTS, LTE, Wi‐Fi, Digital Television, etc.) has meant the inclusion of subjects in technical career studies in which the theoretical and practical aspects are studied and analyzed for planning these systems from a radioelectric point of view. However, the study of these systems is carried out, mainly, through software tools based on Geographic Information Systems (GIS) which implies the need to have prior knowledge of them by the students. In this sense, the majority of students are familiar with Google Earth because it has been used previously by them. This paper presents RadioEarth, a tool developed in JAVA, which interacts with Google Earth and allows simulations and analysis of radio coverage of wireless systems from an educational perspective.
Soploon: A virtual assistant to help teachers to detect object‐oriented errors in students’ source codes
Authors: Vallejos Sebastián , Berdun Luis S. , Armentano Marcelo G. , Soria Álvaro , Teyseyre Alfredo R.
Published: July 2018

When checking students’ source codes, teachers tend to overlook some errors. This work introduces Soploon, a tool that automatically detects novice programmer errors. By using this tool, teachers can reduce the number of overlooked errors. Thus, students receive a more complete and exhaustive feedback about their errors and misconceptions.
Eu3+‐Activated Gd8V2O17: Energy Transfer, Luminescence, and Temperature‐Dependence Characteristics
Authors: Deng Bin , Liu Shihua , Zhou Chong‐song , Liu Hui , Chen Jun , Yu Ruijin
Published: July 2018

A new phosphor of the type Gd8(1−x)Eu8 xV2O17 (x=0–1.0) was synthesized through the solid‐state reaction ceramics method. A pure phase formation was verified by using X‐ray powder diffraction measurements. The luminescence of Gd8V2O17:Eu3+ was investigated through optical and laser excitation spectroscopy. The luminescence curves were investigated in the temperature region 10 to 300 K. Gd8V2O17 shows a self‐activated luminescence under excitation with UV‐ and near‐UV light. The spectra, the decay lifetimes, and the thermal stability of Gd8(1−x)Eu8 xV2O17 (x=0.005–1.0) strongly depend on both the Eu3+ concentration and the temperature. The tunable luminescence is realized by controlling the Eu3+‐doping level to adjust the host energy‐transfer efficiency from the VO43− groups to the Eu3+ activators. At low Eu3+ concentrations (<30 mol %), the intensity and lifetime show an unusual change with an increase of the temperature from 10–300 K, that is, the luminescence experiences a straightforward enhancement. The energy transfer from the VO43− group to the Eu3+ ions could be accelerated with an increase of the temperature resulting in an unusual enhancement of the Eu3+ luminescence and lifetime. However, the emission of the Eu3+ ions decreased for highly Eu‐doped samples (>30 mol %) with an increase of the temperature. The luminescence mechanism was discussed on the basis of the charge‐transfer band of the Eu3+ ions, the doping concentration, and the proposed microstructures in the lattices.
Graphenide Solutions: A Chemical Platform for Nanoparticle–Nanocarbon Composites
Authors: Hof Ferdinand , Pénicaud Alain
Published: July 2018

Graphenide solutions, comprising charged graphene layers in aprotic organic solutions, are exploited as a chemical platform to graft transition‐metal oxide nanoparticles, namely nickel, manganese, copper, and cobalt oxide, onto the carbon framework. The reduction process is driven and controlled by the graphenide solution yielding nanoparticles with comparable sizes for all studied metal salts, well below 10 nm. The synthesis is generic and is not limited by the type of metal salt, because the reduced graphene layers serve simultaneously as both substrates and reducing agents. This reaction is reliable, reproducible, and versatile, generating materials for catalytic purposes without requiring any kind of stabilization or capping agents.
Boosting Lithium Storage Properties of MOF Derivatives through a Wet‐Spinning Assembled Fiber Strategy
Authors: Zhang Lin , Liu Wenxian , Shi Wenhui , Xu Xilian , Mao Jing , Li Peng , Ye Chenzeng , Yin Ruilian , Ye Shaofeng , Liu Xiaoyue , Cao Xiehong , Gao Chao
Published: July 2018

Graphene composite fibers are of great importance in constructing electrode materials with high flexibility and conductivity for energy storage and electronic devices. Integration of multifunctional metal–organic frameworks (MOFs) into graphene fiber scaffolds enables novel functions and enhanced physical/chemical properties. The close‐packed and aligned graphene sheets along with the porous MOF‐derived structures can achieve excellent lithium storage performance through synergetic effects. In this work, a facile and general strategy is demonstrated for the preparation of MOF/graphene oxide (GO) fibers, which serve as precursors for the subsequent preparation of porous metal oxide/reduced graphene oxide (rGO) composite fibers. The obtained composites, for example, porous Fe2O3/rGO and Co3O4/rGO fibers, possess unique features of MOF‐derived porous structures and excellent electrical conductivity. When tested as anode materials for lithium‐ion batteries in coin cells, the MOF/GO fiber‐derived porous metal oxide/rGO composite fibers exhibited high specific capacity, excellent rate capability and cycling performance. Moreover, a flexible fiber battery was fabricated based on the Fe2O3/rGO composite fiber, which demonstrates its potential application for flexible electronic devices.
Magnesium Stung by Nonclassical Scorpionate Ligands: Synthesis and Cone‐Angle Calculations
Authors: Stuhl Christoph , Maichle‐Mössmer Cäcilia , Anwander Reiner
Published: July 2018

A series of tris(pyrazolyl)alkane (RCTp) scorpionate ligands of the type RCTp3‐R′ (R=Me, nBu, SiMe3; R′=H, Me, Ph, iPr, tBu) were synthesized and their ability to coordinate methylmagnesium moieties was examined. The reaction of Mg(AlMe4)2 with neutral proligands HCTp3‐Ph or Me3SiCTp3‐Me, containing a non‐innocent backbone methine moiety, led to deprotonation/rearrangement and SiMe3/AlMe3 exchange to afford [(Me3AlCTp3‐Ph)2Mg] and [(Me3AlCTp3‐Me)Mg(AlMe4)], respectively, with monoanionic tripodal ligands. Treatment of sterically less demanding RCTp3‐R′ with Mg(AlMe4)2 produced isostructural dicationic “metal‐in‐a‐box” complexes of the type [(RCTp3‐R′)2Mg][AlMe4]2 (R=Me, nBu; R′=H, Me). Utilization of the superbulky ligands MeCTp3‐Ph and MeCTp3‐tBu gave monocationic complexes [(MeCTp3‐Ph)MgMe][AlMe4] and [(MeCTp3‐tBu)MgMe][Al2Me7] as separated ion pairs. The reaction of Mg(AlMe4)2 with nBuCTp3‐Ph led to the formation of the dimagnesium complex [{(nBuCTp3‐Ph)Mg(AlMe4)}2(μ‐CH3)], which features a bridging methyl moiety and terminal η1‐coordinated tetramethylaluminato ligands. Isopropyl‐substituted ligand MeCTp3‐iPr emerged from further fine‐tuning of the steric and electronic parameters and, upon reaction with Mg(AlMe4)2, gave (MeCTp3‐iPr)Mg(AlMe4)2; this represents the first example of a magnesium bis(alkyl) complex with an intact RCTp3‐R′ ligand. The exact ligand cone angles Θ° of all magnesium complexes were determined according to the mathematical analysis developed by Allen et al. [J. Comput. Chem. 2013, 34, 1189–1197].
Carbon2Polymer – Conceptual Design of a CO2‐Based Process for the Production of Isocyanates
Authors: Kaiser Teresa , Rathgeb Andrea , Gertig Christoph , Bardow André , Leonhard Kai , Jupke Andreas
Published: July 2018

The capture of carbon dioxide and its utilization as a building block in chemical synthesis aim at reducing the depletion of fossil resources and the emission of greenhouse gases. The project Carbon2Chem®‐L5 is dedicated to the development of processes using CO2 for the production of polymer building blocks for polyurethanes. In this work, a process concept is presented for the CO2‐based synthesis of diisocyanates, the main starting material in polyurethane manufacture. Key parameters for process performance are discussed.
Fabrication of GaN(1−x)Asx, Zinc‐Blende, or Wurtzite GaN Depending on GaAs Nitridation Temperature in a CVD System
Authors: Ramírez‐González Francisco Sebastian , García‐Salgado Godofredo , Morales Crisóforo , Díaz Tomás , Rosendo Enrique , Nieto‐Caballero Fabiola Gabriela , Luna José Alberto , Coyopol Antonio , Romano Román , Galeazzi Reina
Published: July 2018

The study of GaN morphology and structure modification due to the variation of the nitridation temperature are reported. GaN is obtained by nitridation of GaAs (1 1 1) using the flow of a mixture of hydrogen and ammonia into a horizontal CVD system. The experiments are carried out at atmospheric pressures of 800, 900, and 1000 °C for 1 h. XRD results together with the pole figure indicate that GaN(1‐x)Asx is obtained at 800 °C, that zinc‐blende GaN structure is obtained at 900 °C, and that wurtzite GaN structure is obtained at 900 °C. The photoluminescence emission peak (obtained at room temperature) shifts to 420, 384, and 372 nm with the nitridation temperature change, in agreement with the XRD and pole figure results. SEM images show the morphology change, where GaN(1−x)Asx and GaN layers are obtained at 800 and 900 °C, respectively, while GaN columns are obtained at 1000 °C. The morphology and structure change due the nitridation temperature variation are also discussed based on the results.
Optimizing Mass Transfer Control Using a Stirring Paddle for the Rapid Growth of KDP Crystals
Authors: Hu Kaiwei , Zheng Lili , Zhang Hui , Chen Duanyang , Qi Hongji
Published: July 2018

Numerical simulations are performed to study the rapid growth of potassium dihydrogen phosphate crystals with a designed stirring paddle. The paddle is expected to produce a downward flow and enhance mass transfer near the crystal surface. The effects of rotation rate and crystal size on downward flow speed are investigated. As the rotation rate and crystal size increase, the downward flow speed increases linearly. The mass transport in the turbulent boundary layer is analyzed, and the surface supersaturation is calculated theoretically. The solute supply can be guaranteed by controlling the rotation speed of the stirring paddle during crystal growth.
Dichloro‐Substituted 1,2‐Diazabuta‐1,3‐dienes as Highly Reactive Electrophiles in the Reaction with Amines and Diamines: Efficient Synthesis of α‐Hydrazo Amidinium Salts
Authors: Shastin Alexey V. , Sergeev Pavel G. , Lukianova Anna I. , Muzalevskiy Vasiliy M. , Khrustalev Victor N. , Dorovatovskii Pavel V. , Nenajdenko Valentine G.
Published: July 2018

The reaction of 4,4‐dichloro‐1,2‐diazabuta‐1,3‐dienes with various amines and diamines was studied. We found that in this reaction, the starting diazabutadienes behave as highly reactive electrophiles to open up a straightforward route to the corresponding amidinium salts with a hydrazone functionality in the adjacent position. The reaction was found to be very general; as a rule, all the products could be prepared in almost quantitative yields. We also demonstrated that the prepared amidinium salts could be used as versatile building blocks for the synthesis of polyfunctional molecules.
Technical comment—Ten fundamental principles on defining and expressing thermal exposure as boundary conditions in fire safety engineering
Authors: Wickström Ulf , Hunt Sean , Lattimer Brian , Barnett Jonathan , Beyler Craig
Published: July 2018

Predicting the temperature of an exposed object or even a person is one of the most common tasks of fire safety engineering. However, the nonlinear nature of heat transfer and the challenge of changing material properties with temperature have plagued precise predictions. In addition, as methodologies are developed, one of the biggest challenges is to apply them to known scenarios where temperatures and heat fluxes have been measured. The interpretations of such measurements are, however, often clouded by the lack of common understanding of the reported values and how they shall be translated into boundary conditions to be used for calculations. This technical comment summarizes the Fundamental Principles that are crucial to properly identifying the fire exposure so that appropriate temperature predictions can be made.
Characterizing the heterogeneity of karst critical zone and its hydrological function: An integrated approach
Authors: Chen Xi , Zhang Zhicai , Soulsby Chris , Cheng Qinbo , Binley Andrew , Jiang Rui , Tao Min
Published: July 2018

Spatial heterogeneity in the subsurface of karst environments is high, as evidenced by the multiphase porosity of carbonate rocks and complex landform features that result in marked variability of hydrological processes in space and time. This includes complex exchange of various flows (e.g., fast conduit flows and slow fracture flows) in different locations. Here, we integrate various “state‐of‐the‐art” methods to understand the structure and function of this poorly constrained critical zone environment. Geophysical, hydrometric, and tracer tools are used to characterize the hydrological functions of the cockpit karst critical zone in the small catchment of Chenqi, Guizhou Province, China. Geophysical surveys, using electrical resistivity tomography (ERT), inferred the spatial heterogeneity of permeability in the epikarst and underlying aquifer. Water tables in depression wells in valley bottom areas, as well as discharge from springs on steeper hillslopes and at the catchment outlet, showed different hydrodynamic responses to storm event rainwater recharge and hillslope flows. Tracer studies using water temperatures and stable water isotopes (δD and δ18O) could be used alongside insights into aquifer permeability from ERT surveys to explain site‐ and depth‐dependent variability in the groundwater response in terms of the degree to which “new” water from storm rainfall recharges and mixes with “old” pre‐event water in karst aquifers. This integrated approach reveals spatial structure in the karst critical zone and provides a conceptual framework of hydrological functions across spatial and temporal scales.
Assessment of alternative adsorption models and global sensitivity analysis to characterize hexavalent chromium loss from soil to surface runoff
Authors: Xia Chuan‐An , Tong Juxiu , Hu Bill X. , Wu Xiujie , Guadagnini Alberto
Published: July 2018

We investigate our ability to assess transfer of hexavalent chromium, Cr(VI), from the soil to surface runoff by considering the effect of coupling diverse adsorption models with a two‐layer solute transfer model. Our analyses are grounded on a set of two experiments associated with soils characterized by diverse particle size distributions. Our study is motivated by the observation that Cr(VI) is receiving much attention for the assessment of environmental risks due to its high solubility, mobility, and toxicological significance. Adsorption of Cr(VI) is considered to be at equilibrium in the mixing layer under our experimental conditions. Four adsorption models, that is, the Langmuir, Freundlich, Temkin, and linear models, constitute our set of alternative (competing) mathematical formulations. Experimental results reveal that the soil samples characterized by the finest grain sizes are associated with the highest release of Cr(VI) to runoff. We compare the relative abilities of the four models to interpret experimental results through maximum likelihood model calibration and four model identification criteria (i.e., the Akaike information criteria [AIC and AICC] and the Bayesian and Kashyap information criteria). Our study results enable us to rank the tested models on the basis of a set of posterior weights assigned to each of them. A classical variance‐based global sensitivity analysis is then performed to assess the relative importance of the uncertain parameters associated with each of the models considered, within subregions of the parameter space. In this context, the modelling strategy resulting from coupling the Langmuir isotherm with a two‐layer solute transfer model is then evaluated as the most skilful for the overall interpretation of both sets of experiments. Our results document that (a) the depth of the mixing layer is the most influential factor for all models tested, with the exception of the Freundlich isotherm, and (b) the total sensitivity of the adsorption parameters varies in time, with a trend to increase as time progresses for all of the models. These results suggest that adsorption has a significant effect on the uncertainty associated with the release of Cr(VI) from the soil to the surface runoff component.
The metastatic microenvironment: Melanoma–microglia cross‐talk promotes the malignant phenotype of melanoma cells
Authors: Izraely Sivan , Ben‐Menachem Shlomit , Sagi‐Assif Orit , Telerman Alona , Zubrilov Inna , Ashkenazi Ofir , Meshel Tsipi , Maman Shelly , Orozco Javier I.J. , Salomon Matthew P. , Marzese Diego M. , Pasmanik‐Chor Metsada , Pikarski Eli , Ehrlich Marcelo , Hoon Dave S.B. , Witz Isaac P.
Published: July 2018

Melanoma has the highest propensity to metastasize to the brain compared to other cancers, as brain metastases are found frequently high in patients who have prolonged survival with visceral metastasis. Once disseminated in the brain, melanoma cells communicate with brain resident cells that include astrocytes and microglia. Microglia cells are the resident macrophages of the brain and are the main immunological cells in the CNS involved in neuroinflammation. Data on the interactions between brain metastatic melanoma cells and microglia and on the role of microglia‐mediated neuroinflammation in facilitating melanoma brain metastasis are lacking. To elucidate the role of microglia in melanoma brain metastasis progression, we examined the bidirectional interactions between microglia and melanoma cells in the tumor microenvironment. We identified the molecular and functional modifications occurring in brain‐metastasizing melanoma cells and microglia cells after the treatment of each cell type with supernatants of the counter cell type. Both cells induced alteration in gene expression programs, cell signaling, and cytokine secretion in the counter cell type. Moreover, melanoma cells exerted significant morphological changes on microglia cells, enhanced proliferation, induced matrix metalloproteinase‐2 (MMP‐2) activation, and cell migration. Microglia cells induced phenotypic changes in melanoma cells increasing their malignant phenotype: increased melanoma proliferation, MMP‐2 activity, cell migration, brain endothelial penetration, and tumor cells ability to grow as spheroids in 3D cultures. Our work provides a novel insight into the bidirectional interactions between melanoma and micoglia cells, suggesting the contribution of microglia to melanoma brain metastasis formation.
Novel amides of 1,1‐bis‐(carboxymethylthio)‐1‐arylethanes: Synthesis, characterization, acetylcholinesterase, butyrylcholinesterase, and carbonic anhydrase inhibitory properties
Authors: Taslimi Parham , Osmanova Sabiya , Caglayan Cuneyt , Turkan Fikret , Sardarova Sabira , Farzaliyev Vagif , Sujayev Afsun , Sadeghian Nastaran , Gulçin İlhami
Published: July 2018

The thiolation reaction was carried out in a benzene solution at 80°C and p‐substituted ketones and mercaptoacetic acid in a molar ratio (1:4) of in the presence of a catalytic amount of toluene sulfonic acids. The enzyme inhibition activities of the novel amides of 1,1‐bis‐(carboxymethylthio)‐1‐arylethanes derivatives were investigated. These novel amides of 1,1‐bis‐(carboxymethylthio)‐1‐arylethanes derivatives showed good inhibitory action against acetylcholinesterase (AChE) butyrylcholinesterase (BChE), and human carbonic anhydrase I and II isoforms (hCA I and II). AChE inhibitors, interacting with the enzyme as their primary target, are applied as relevant drugs and toxins. Many clinically established drugs are carbonic anhydrase inhibitors, and it is highly anticipated that many more will eventually find their way into the market. The novel synthesized compounds inhibited AChE and BChE with Ki values in the range of 0.64–1.47 nM and 9.11–48.12 nM, respectively. On the other hand, hCA I and II were effectively inhibited by these compounds, with Ki values between 63.27–132.34 and of 29.63–127.31 nM, respectively.
The synthesis of N‐benzoylindoles as inhibitors of rat erythrocyte glucose‐6‐phosphate dehydrogenase and 6‐phosphogluconate dehydrogenase
Authors: Bayindir Sinan , Temel Yusuf , Ayna Adnan , Ciftci Mehmet
Published: July 2018

Glucose‐6‐phosphate dehydrogenase (G6PD) and 6‐phosphogluconate dehydrogenase (6PGD) play an important function in various biochemical processes as they generate reducing power of the cell. Thus, metabolic reprogramming of reduced nicotinamide adenine dinucleotide phosphate (NADPH) homeostasis is reported to be a vital step in cancer progression as well as in combinational therapeutic approaches. In this study, N‐benzoylindoles 9a‐‐9d, which form the main framework of many natural indole derivatives such as indomethacin and N‐benzoylindoylbarbituric acid, were synthesized through three easy and effective steps as an in vitro inhibitor effect of G6PD and 6PGD. The N‐benzoylindoles inhibited the enzymatic activity with IC50 in the range of 3.391505 μM for G6PD and 2.19–990 μM for 6PGD.
Association of CD28 and CTLA4 haplotypes with susceptibility to primary Sjögren′s syndrome in Mexican population
Authors: López‐Villalobos Erika Fabiola , Carrillo‐Ballesteros Francisco Josué , Muñoz‐Valle José Francisco , Palafox‐Sánchez Claudia Azucena , Valle Yeminia , Orozco‐Barocio Gerardo , Oregon‐Romero Edith
Published: July 2018

Background

Primary Sjögren's syndrome (pSS) is an autoimmune disease characterized by destruction of exocrine glands as a result of T and B cells infiltrated in glandular tissue. CD28 and CTLA‐4 play a crucial role in T cell activation and inhibition. The aim of this study was to associate CD28 and CTLA4 haplotypes with susceptibility to pSS in patients from western Mexico.

Methods

Polymerase chain reaction and restriction fragment length polymorphism were performed to identify CD28 and CTLA4 genotypes in 111 patients with pSS and 138 control subjects (CS). Haplotype analysis was carried out by SHEsis program. Soluble serum levels of CD28 (sCD28) and CTLA‐4 (sCTLA‐4) were quantified by ELISA kit.

Results

The CD28 GC haplotype was associated with low risk to pSS (2.5‐folds, P < 0.001). CTLA4 CAG and CGA were identified as genetic risk factor (P < 0.001;OR = 3.82[CI95%:2.022‐7.296] and P < 0.001; OR = 11.38[CI95%:3.282‐37.69] respectively). No difference in sCD28 and sCTLA‐4 were found between patients and CS. However, pSS patients carriers of CD28 IVS3 + 17TC genotype showed high sCD28 (P = 0.039 vs TT carriers in CS). In regard to sCTLA‐4, patient who carry CTLA4‐319C>T, +49 A>G, and +6230 G>A, or their haplotypes did not show any difference.

Conclusion

Our findings suggest that CD28 GC, CTLA4 CAG, and CGA haplotypes are associated with susceptibility to pSS in patients from western Mexico. It seems that genetic control of CD28 and CTLA4 as well as local immune response in glandular tissue may regulate the impact of the gene expression in pSS. It is necessary to confirm this hypothesis in an integrative study.
An optimized culture system for notochordal cell expansion with retention of phenotype
Authors: Humphreys Matthew D. , Ward Lizzy , Richardson Stephen M. , Hoyland Judith A.
Published: July 2018

Background

Notochordal (NC) cells display therapeutic potential in treating degeneration of the intervertebral disc. However, research on their phenotype and function is limited by low‐cell yields and a lack of appropriate methodology for cell expansion. Utilizing porcine cells, this study aimed to develop an optimized culture system which allows expansion of NC cell populations with retention of phenotype.

Methods

Post‐natal porcine and foetal human nucleus pulposus tissue was compared histologically and expression of known NC cell marker genes by porcine NC cells was analyzed. Porcine NC cells were isolated from six‐week post‐natal discs and cultured in vitro under varied conditions: (1) DMEM vs αMEM; (2) laminin‐521, fibronectin, gelatin and uncoated tissue culture‐treated polystyrene (TCP); (3) 2% O2 vs normoxia; (4) αMEM (300 mOsm/L) vs αMEM (400 mOsm/L); (5) surface stiffness of 0.5 and 4 kPa and standard TCP. Adherence, proliferation, morphology and expression of NC cell markers were assessed over a 14‐day culture period.

Results

Native porcine nucleus pulposus tissue demonstrated similar morphology to human foetal tissue and porcine NC cells expressed known notochordal markers (CD24, KRT8, KRT18, KRT19, and T). Use of αMEM media and laminin‐521‐coated surfaces showed the greatest cell adherence, proliferation and retention of NC cell morphology and phenotype. Proliferation of NC cell populations was further enhanced in hypoxia (2%) and phenotypic retention was improved on 0.5 kPa culture surfaces.

Discussion

Our model has demonstrated an optimized system in which NC cell populations may be expanded while retaining a notochordal phenotype. Application of this optimized culture system will enable NC cell expansion for detailed phenotypic and functional study, a major advantage over current culture methods described in the literature. Furthermore, the similarities identified between porcine and human NC cells suggest this system will be applicable in human NC cell culture for investigation of their therapeutic potential.