bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intermediate‐Dependent Unusual [4+3], [3+2] and Cascade Reactions of 3‐Indolylmethanols: Controllable Chemodivergent and Stereoselective Synthesis of Diverse Indole Derivatives
Authors: Zhang Hong‐Hao , Zhu Zi‐Qi , Fan Tao , Liang Jing , Shi Feng 
Published: March 2016

AbstractChemodivergent and stereoselective construction of indole‐containing scaffolds, as well as synthesis of diverse indole derivatives, has long been a goal in the chemistry community. In this work, we reveal key intermediate‐dependent unusual [4+3], [3+2] and cascade reactions of 3‐indolylmethanols with Nazarov reagents, leading to controllable chemodivergent and stereoselective synthesis of diverse indole derivatives. (i) In the presence of hydrobromic acid in acetonitrile, 3‐indolylmethanols performed an electronically reversed [4+3] cyclization with Nazarov reagents, thus constructing a cyclohepta[b]indole framework with the concomitant creation of an all‐carbon seven‐membered ring bearing a quaternary stereocenter in a highly diastereoselective fashion. (ii) Under the promotion of hydrobromic acid in fluorobenzene, methyl‐protected 3‐indolylmethanols underwent site‐selective [3+2] cyclization with Nazarov reagents, which built up a cyclopenta[b]indole skeleton bearing a spiro‐quaternary stereocenter in high chemical yields. (iii) By changing the acid to trifluoromethanesulfonic acid in acetonitrile, the same reactants carried out a cascade reaction to afford the corresponding indole derivatives by generating multiple new CC bonds in an (E/Z)‐selective mode. Based on control experiments, these reactions were found to be dependent on the formation of a key type of intermediate, which underwent a variety of unusual transformations including CC bond cleavage and reassembly under different reaction conditions to afford diverse indole derivatives. These unusual reactions not only for the first time establish several challenging new transformations of 3‐indolylmethanols with precise control of chemo‐, diastereo‐ and (E/Z)‐selectivity, but also provide efficient methods for constructing indole‐containing scaffolds in a stereoselective and chemodivergent manner.magnified image
But‐2‐ene‐1,4‐diamine and But‐2‐ene‐1,4‐diol as Donors for Thermodynamically Favored Transaminase‐ and Alcohol Dehydrogenase‐Catalyzed Processes
Authors: Martínez‐Montero Lía , Gotor Vicente , Gotor‐Fernández Vicente , Lavandera Iván 
Published: March 2016

AbstractBoth cis‐ and trans‐but‐2‐ene‐1,4‐diamines have been prepared and efficiently applied as sacrificial cosubstrates in enzymatic transamination reactions. The best results were obtained with the cis‐diamine. The thermodynamic equilibrium of the stereoselective transamination process is shifted to the amine formation due to tautomerization of 5H‐pyrrole into 1H‐pyrrole, achieving high conversions (78–99%) and enantiomeric excess (up to >99%) by using a small excess of the amine donor. Furthermore, when the reaction proceeded, a strong coloration was observed due to polymerization of 1H‐pyrrole. A structurally related compound, cis‐but‐2‐ene‐1,4‐diol, has been utilized as cosubstrate in different alcohol dehydrogenase (ADH)‐mediated bioreductions. In this case, high conversions (91–99%) were observed due to a lactonization process. Both strategies are convenient from both synthetic and atom economy points of view in the production of valuable optically active products.magnified image
A bioarchaeological analysis of oral and physiological health on the south coast of New Guinea
Authors: Kinaston Rebecca L. , Roberts Georgia L. , Buckley Hallie R. , Oxenham Marc 
Published: March 2016

ABSTRACTObjectivesThe south coast of New Guinea has a complex prehistory known for its exchange systems that linked distinct cultural groups living along the coast, inland, and on offshore islands. Here we compare the palaeohealth of two relatively contemporaneous skeletal samples from the south coast of New Guinea (850–200 BP) that were from two ecologically different sites (one inland and one offshore island) and likely represent distinct cultural groups. We aim to elucidate health patterns that may provide information about the specific lifeways and quality of life of each community.Materials and MethodsOral conditions (caries, calculus, alveolar lesions, and antemortem tooth loss [AMTL]) were analyzed macroscopically to assess possible intra‐ and inter‐population variation in oral and physiological health. The frequency of linear enamel hypoplasia (LEH) was also used as a nonspecific indicator of stress to assess childhood health at each site.ResultsThe inhabitants from the small offshore island of Motupore, thought to be associated with Austronesian‐speaking Motu tribes, displayed different patterns of oral pathological conditions (more carious lesions on the tooth crown and calculus) and LEH (lower frequencies) compared with inland people residing at the site of Nebira.DiscussionIt is suggested that the causes for the variation in oral and physiological health were likely multifactorial and potentially associated with variables such as the ecological and geographical settings of the sites, cultural differences, infectious disease, differential fertility and, potentially, diet. This research provides previously unknown information about possible culturally‐moderated practices that affected health in the past. Am J Phys Anthropol 160:414–426, 2016. © 2016 Wiley Periodicals, Inc.
Microfluidic Synthesis Enables Dense and Uniform Loading of Surfactant‐Free PtSn Nanocrystals on Carbon Supports for Enhanced Ethanol Oxidation
Authors: Wu Fuxiang , Zhang Dongtang , Peng Manhua , Yu Zhihui , Wang Xiayan , Guo Guangsheng , Sun Yugang 
Published: March 2016

AbstractDeveloping new synthetic methods for carbon supported catalysts with improved performance is of fundamental importance in advancing proton exchange membrane fuel cell (PEMFC) technology. Continuous‐flow, microfluidic reactions in capillary tube reactors are described, which are capable of synthesizing surfactant‐free, ultrafine PtSn alloyed nanoparticles (NPs) on various carbon supports (for example, commercial carbon black particles, carbon nanotubes, and graphene sheets). The PtSn NPs are highly crystalline with sizes smaller than 2 nm, and they are highly dispersed on the carbon supports with high loadings up to 33 wt %. These characteristics make the as‐synthesized carbon‐supported PtSn NPs more efficient than state of the art commercial Pt/C catalysts applied to the ethanol oxidation reaction (EOR). Significantly enhanced mass catalytic activity (two‐times that of Pt/C) and improved stability are obtained.
Übergangsmetallcarbodiimide als molekulare negative Elektroden‐ materialien für Li‐ und Na‐Ionenbatterien mit hervorragendem Zyklisierungsverhalten
Authors: Sougrati Moulay T. , Darwiche Ali , Liu Xiaohiu , Mahmoud Abdelfattah , Hermann Raphael P. , Jouen Samuel , Monconduit Laure , Dronskowski Richard , Stievano Lorenzo 
Published: March 2016

AbstractWir weisen die elektrochemische Aktivität von Übergangsmetallcarbodiimiden gegenüber Lithium und Natrium nach. Insbesondere das Eisencarbodiimid FeNCN läßt sich effektiv als negatives Elektrodenmaterial für Alkalimetallionenbatterien verwenden, ähnlich dem Oxidanalogon FeO. Auf der Basis von 57Fe‐Mößbauer‐ und infrarotspektroskopischen (IR) Daten kann der elektrochemische Reaktionsmechanismus bei Entladung und Beladung durch die reversible Umwandlung von Fe‐NCN‐ in Li/Na‐NCN‐Bindungen erklärt werden. Diese neuen Elektrodenmaterialien weisen höhere Kapazitäten als die etablierten negativen Referenzelektroden wie Graphit oder Hartkohlenstoff auf. Im Gegensatz zu seinem Oxidanalogon benötigt Eisencarbodiimid keine aufwendige Vorbehandlung (Nanopräparation, spezielle Texturen, Beschichtung usw.), um eine lange Lebensdauer bei Stromdichten bis zu 9 A g−1 für hunderte von Lade‐/Entladezyklen zu erreichen. Ähnlich zur Eisenverbindung können einige andere Übergangsmetallcarbodiimide Mx(NCN)y mit M=Mn, Cr, Zn ebenso erfolgreich gegen Lithium und Natrium zyklisieren. Ihre elektrochemische Aktivität und Leistung öffnet den Weg zum Design einer neuartigen Klasse von Anodenmaterialien.
Single‐Face/All‐cis Arene Hydrogenation by a Supported Single‐Site d0 Organozirconium Catalyst
Authors: Stalzer Madelyn Marie , Nicholas Christopher P. , Bhattacharyya Alak , Motta Alessandro , Delferro Massimiliano , Marks Tobin J. 
Published: March 2016

AbstractThe single‐site supported organozirconium catalyst Cp*ZrBz2/ZrS (Cp*=Me5C5, Bz=benzyl, ZrS=sulfated zirconia) catalyzes the single‐face/all‐cis hydrogenation of a large series of alkylated and fused arene derivatives to the corresponding all‐cis‐cyclohexanes. Kinetic/mechanistic and DFT analysis argue that stereoselection involves rapid, sequential H2 delivery to a single catalyst‐bound arene face, versus any competing intramolecular arene π‐face interchange.
Plasma‐Engraved Co3O4 Nanosheets with Oxygen Vacancies and High Surface Area for the Oxygen Evolution Reaction
Authors: Xu Lei , Jiang Qianqian , Xiao Zhaohui , Li Xingyue , Huo Jia , Wang Shuangyin , Dai Liming 
Published: March 2016

AbstractCo3O4, which is of mixed valences Co2+ and Co3+, has been extensively investigated as an efficient electrocatalyst for the oxygen evolution reaction (OER). The proper control of Co2+/Co3+ ratio in Co3O4 could lead to modifications on its electronic and thus catalytic properties. Herein, we designed an efficient Co3O4‐based OER electrocatalyst by a plasma‐engraving strategy, which not only produced higher surface area, but also generated oxygen vacancies on Co3O4 surface with more Co2+ formed. The increased surface area ensures the Co3O4 has more sites for OER, and generated oxygen vacancies on Co3O4 surface improve the electronic conductivity and create more active defects for OER. Compared to pristine Co3O4, the engraved Co3O4 exhibits a much higher current density and a lower onset potential. The specific activity of the plasma‐engraved Co3O4 nanosheets (0.055 mA cm−2BET at 1.6 V) is 10 times higher than that of pristine Co3O4, which is contributed by the surface oxygen vacancies.
A Drug‐Free Tumor Therapy Strategy: Cancer‐Cell‐Targeting Calcification
Authors: Zhao Ruibo , Wang Ben , Yang Xinyan , Xiao Yun , Wang Xiaoyu , Shao Changyu , Tang Ruikang 
Published: March 2016

AbstractHerein, we propose a drug‐free approach to cancer therapy that involves cancer cell targeting calcification (CCTC). Several types of cancer cells, such as HeLa cells, characterized by folate receptor (FR) overexpression, can selectively adsorb folate (FA) molecules and then concentrate Ca2+ locally to induce specific cell calcification. The resultant calcium mineral encapsulates the cancer cells, inducing their death, and in vivo assessments confirm that CCTC treatment can efficiently inhibit tumor growth and metastasis without damaging normal cells compared with conventional chemotherapy. Accordingly, CCTC remarkably improve the survival rate of tumor mice. Notably, both FA and calcium ions are essential ingredients in human metabolism, which means that CCTC is a successful drug‐free method for tumor therapy. This achievement may further represent an alternative cancer therapy characterized by selective calcification‐based substitution of sclerosis for tumor disease.
Facile Recoding of Selenocysteine in Nature
Authors: Mukai Takahito , Englert Markus , Tripp H. James , Miller Corwin , Ivanova Natalia N. , Rubin Edward M. , Kyrpides Nikos C. , Söll Dieter 
Published: March 2016

AbstractSelenocysteine (Sec or U) is encoded by UGA, a stop codon reassigned by a Sec‐specific elongation factor and a distinctive RNA structure. To discover possible code variations in extant organisms we analyzed 6.4 trillion base pairs of metagenomic sequences and 24 903 microbial genomes for tRNASec species. As expected, UGA is the predominant Sec codon in use. We also found tRNASec species that recognize the stop codons UAG and UAA, and ten sense codons. Selenoprotein synthesis programmed by UAG in Geodermatophilus and Blastococcus, and by the Cys codon UGU in Aeromonas salmonicida was confirmed by metabolic labeling with 75Se or mass spectrometry. Other tRNASec species with different anticodons enabled E. coli to synthesize active formate dehydrogenase H, a selenoenzyme. This illustrates the ease by which the genetic code may evolve new coding schemes, possibly aiding organisms to adapt to changing environments, and show the genetic code is much more flexible than previously thought.
Synthesis of Chiral 1,4‐Benzodioxanes and Chromans by Enantioselective Palladium‐Catalyzed Alkene Aryloxyarylation Reactions
Authors: Hu Naifu , Li Ke , Wang Zheng , Tang Wenjun 
Published: March 2016

AbstractA highly enantioselective alkene aryloxyarylation led to the high‐yielding formation of a series of 1,4‐benzodioxanes, 1,4‐benzooxazines, and chromans containing quaternary stereocenters with excellent enantioselectivity. The sterically bulky and conformationally well defined chiral monophosphorus ligand L4 or L5 was responsible for the high reactivity and enantioselectivity of these transformations. The application of this method to the synthesis of the chiral chroman backbone of α‐tocopherol was demonstrated.
H2‐Fueled ATP Synthesis on an Electrode: Mimicking Cellular Respiration
Authors: Gutiérrez‐Sanz Óscar , Natale Paolo , Márquez Ileana , Marques Marta C. , Zacarias Sonia , Pita Marcos , Pereira Inês A. C. , López‐Montero Iván , De Lacey Antonio L. , Vélez Marisela 
Published: March 2016

AbstractATP, the molecule used by living organisms to supply energy to many different metabolic processes, is synthesized mostly by the ATPase synthase using a proton or sodium gradient generated across a lipid membrane. We present evidence that a modified electrode surface integrating a NiFeSe hydrogenase and a F1F0‐ATPase in a lipid membrane can couple the electrochemical oxidation of H2 to the synthesis of ATP. This electrode‐assisted conversion of H2 gas into ATP could serve to generate this biochemical fuel locally when required in biomedical devices or enzymatic synthesis of valuable products.
Kinetically Controlled Sequential Growth of Surface‐Grafted Chiral Supramolecular Copolymers
Authors: Frisch Hendrik , Fritz Eva‐Corinna , Stricker Friedrich , Schmüser Lars , Spitzer Daniel , Weidner Tobias , Ravoo Bart Jan , Besenius Pol 
Published: March 2016

AbstractWe report a facile strategy to grow supramolecular copolymers on Au surfaces by successively exposing a surface‐anchored monomer to solutions of oppositely charged peptide comonomers. Charge regulation on the active chain end of the polymer sufficiently slows down the kinetics of the self‐assembly process to produce kinetically trapped copolymers at near‐neutral pH. We thereby achieve architectural control at three levels: The β‐sheet sequences direct the polymerization away from the surface, the height of the supramolecular copolymer brushes is well‐controlled by the stepwise nature of the alternating copolymer growth, and 2D spatial resolution is realized by using micropatterned initiating monomers. The programmable nature of the resulting architectures renders this concept attractive for the development of customized biomaterials or chiral interfaces for optoelectronics and sensor applications.
Synthesis of a melamine‐cyclotriphosphazene derivative and its application as flame retardant on cotton gauze
Authors: Lv Meixiang , Yao Chunfeng , Yang Dingqiao , Zeng Heping 
Published: March 2016

ABSTRACTThe halogen‐free flame retardance of natural fiber is an everlasting challenge due to the well‐known poor solubility of phosphazene in water. In this case, a new cyclotriphosphazene derivative (MCP) was synthesized. It was etherized hexamethylolmelamine (HMMM) and hexachloro‐cyclotriphosphazene (HCCP) by one pot reaction. It was characterized by1H NMR,13C NMR,31P NMR, FT‐IR, TGA, SEM, limited oxygen index (LOI) and vertical flame testing. The MCP has good solubility in water and thermosetting MCP has compact structure which can expand several times after burning. Cotton gauze was soaked in six different concentration of aqueous solutions of MCP (0 wt %, 5 wt %, 10 wt %, 15 wt %, 20 wt % and 25 wt %, respectively) to obtain the flame retardant cloth. The cloth was soaked in 20 wt % MCP solution had higher char yield and LOI. They had no any afterflame and afterglow, and gauze 2‐ gauze 5 cannot be burned out in 12s ignition time. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2016,133, 43555.
The behavior of natural rubber–epoxidized natural rubber–silica composites based on wet masterbatch technique
Authors: Wang Yueqiong , Liao Lusheng , Zhong Jieping , He Dongning , Xu Kui , Yang Changjin , Luo Yongyue , Peng Zheng 
Published: March 2016

ABSTRACTNatural rubber–epoxidized natural rubber–silica composites were prepared by the wet masterbatch technique and the traditional dry mixing method. Performances of the composites based on different preparation methods were investigated with a moving die rheometer, an electronic universal testing machine, a dynamic mechanical analyzer, a nuclear magnetic resonance crosslink density analyzer, a rubber processing analyzer (RPA), a scanning electron microscope (SEM), and a transmission electron microscope (TEM). The RPA, SEM, and TEM analyses indicated that silica has better dispersion, lower filler–filler interaction, and better filler–rubber interaction in compounds based on the wet masterbatch technique, leading to improvements in mechanical strength and the dynamic mechanical and compression properties of the composites. It also indicates that composites prepared by the wet masterbatch technique have shorter scorch time, faster curing velocity, and higher crosslink density. The composites prepared by the wet materbatch technique also have lower rolling resistance, which is an important property for their use as a green material for the tire industry. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43571.
Relationship between microstructure of lamellar graphene sheets and properties of polyimide/graphene nanocomposites film under different imidization stages
Authors: Ding Xin , Zhang Xian , Bao Chao , Tan Su , Zheng Kang , Chen Lin , Zhang Hui , Tian Xingyou 
Published: March 2016

ABSTRACTHerein, polyimide/graphene sheets (PI/GS) nanocomposite films with different GS distribution structures have been successfully obtained by controlling the imidization degrees, and the effect of the lamellar structure on the properties of PI film has been investigated. The results show that GS are gradually parallel to the surface of PI nanocomposite film with the increase of the imidization temperature, and 150 °C is the critical temperature, where the imidization rate is the fastest and the lamellar structure begins to form. Furthermore, with the drying temperature increasing, the corresponding thermal, electrical and mechanical properties of PI/GS nanocomposite films are significantly improved compared with that of pure PI films, which are ascribed to both the higher imidization degree and the lamellar GS structure. It is noteworthy that the formation process of the lamellar structure at different imidization stages can be directly observed by scanning electron microscope. Based on these results, a model has been proposed to explain the relationship between the lamellar structure and properties of PI composite film under different imidization stages, and the confinement of the thickness may be the most important factor for the formation of lamellar GS structure. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43575.
Risk of Herpes Zoster in Autoimmune and Inflammatory Diseases: Implications for Vaccination
Authors: Yun Huifeng , Yang Shuo , Chen Lang , Xie Fenglong , Winthrop Kevin , Baddley John W. , Saag Kenneth G. , Singh Jasvinder , Curtis Jeffrey R. 
Published: March 2016

ObjectiveThe herpes zoster (HZ) vaccine is recommended for adults in the US ages ≥60 years who do not have weakened immune systems. It is unclear how the risk of HZ varies according to age and disease conditions in younger patients with autoimmune or inflammatory (AI) diseases. This study was undertaken to evaluate the age‐stratified incidence of HZ in patients with AI diseases as compared to older adults for whom the HZ vaccine is currently recommended by the US Centers for Disease Control and Prevention.MethodsUsing linked data obtained from patients who were insured by US commercial and government health care plans during the period 2007–2010, 7 cohorts of patients with AI diseases were assembled: systemic lupus erythematosus (SLE), inflammatory bowel disease (IBD), rheumatoid arthritis (RA), psoriatic arthritis (PsA), psoriasis (PsO), ankylosing spondylitis (AS), and gout. Two comparator cohorts were also assembled as controls: adult patients with diabetes and adult subjects without AI diseases or diabetic conditions. HZ was identified using diagnostic codes. Age‐specific incidence rates (IRs) of HZ were calculated and compared to the IRs of HZ in control subjects ages 61–70 years who were without AI diseases or diabetic conditions.ResultsAfter review of the linked data, the following number of enrollment periods were identified: 8,395 for patients with SLE, 7,916 for patients with IBD, 50,646 for patients with RA, 2,629 for patients with PsA, 4,299 for patients with PsO, 1,019 for patients with AS, 58,934 for patients with gout, 214,631 for control patients with diabetes, and 330,727 for control subjects without AI diseases and diabetic conditions. The respective highest and lowest IRs of HZ during the study were 19.9 per 1,000 person‐years in the SLE cohort and 6.8 per 1,000 person‐years in the gout cohort, as compared to an IR of 5.3 per 1,000 person‐years in control subjects without AI diseases or diabetic conditions. The age‐specific IRs of HZ in patients with RA and those with SLE ages ≥40 years were 1.5–2 times greater than those observed in older healthy adults (IR 8.5 per 1,000 person‐years), for whom the vaccine is currently recommended.ConclusionSLE, IBD, and RA are AI diseases associated with a higher risk of HZ compared to that in older adults for whom vaccination is currently recommended, suggesting that individuals with these conditions who are as young as age 40 years could potentially benefit from the HZ vaccine.