bluuebunny/crossref_metadata_2025_split huggingface dataset:
In‐situ One‐Step Preparation of Nickel‐Tipped N‐doped Carbon Nanotubes for Oxygen Reduction
Authors: Huai Jie , Ma Kongshuo , Lu Yizhong , Chen Tao , Zhao Zhenlu 
Published: August 2019

AbstractHere, we successfully synthesized N‐doped carbon nanotubes embedded with nickel‐based nanoparticles on the top (N‐CNTs/E‐NNPs) by directly procedural calcination of melamine and nickel foam at 520 °C, 540 °C and 700 °C in Ar. When applied for oxygen reduction reaction (ORR), the onset potential and half‐wave potential are 0.96 V and 0.86 V in 0.1 M KOH, comparable to that of the commercial 10 wt% Pt/C. Moreover, the hybrids possess higher stability and better methanol tolerance. Additionally, the Tafel slope of N‐CNTs/E‐NNPs is 76 mV dec−1 in 0.1 M KOH, lower than 83 mV dec−1 of the commercial 10 wt% Pt/C, demonstrating a good kinetic process. The remarkable features are mainly ascribed to synergistic enhancement effect from N‐rich doped carbon nanotubes (N‐CNTs) and embedded Ni‐based nanoparticles on the top, promoting mass and electrons transport, enhancing the activity of active sites and making it a promising highly efficient non‐precious metal ORR catalyst.
Biochemical Conversion of Microalgae Biomass into Biofuel
Authors: Hossain S. M. Zakir 
Published: August 2019

AbstractBiofuel production via microalgae is a promising and sustainable alternative to replace the typical fossil fuel that is the main contributor to the global warming. However, for a cost‐effective biofuel production, further advanced research is still needed for large‐scale operation. This article is a tutorial review on conversion processes of microalgae into biofuel, with emphasis on biochemical conversion. The following topics are discussed: (i) microalgae biomass and its composition, (ii) thermochemical conversion, (iii) chemical conversion, and (iv) biochemical conversion. In addition, various aspects of anaerobic digestion, digester designs, and effects of operating conditions on the production of methane, bioethanol, and biohydrogen are discussed. The general kinetics of biomass conversion into biofuel is presented. This study suggests, if that biomass contains less than 50 % moisture, then it is recommended to use the direct combustion method; otherwise, biochemical conversion is the most suitable process to biofuel production.
Preparative Protein Crystallization
Authors: Hubbuch Jürgen , Kind Matthias , Nirschl Hermann 
Published: August 2019

AbstractPreparative protein crystallization can possibly replace one or more chromatographic steps in downstream processing. The development of such crystallization processes is demanding: first, promising principal crystallization conditions must be identified; second, details about the process must be defined; and third, the crystals have to be separated from the mother liquor without putting harm of their crystalline integrity. State‐of‐the‐art about these three steps is developing fast by (i) employing new screening methods which are based on fundamental understanding of the interaction of the protein molecules, (ii) application of existing concepts of technical bulk crystallization of small molecules to preparative protein crystallization, and (iii) making available specific gentle separation machinery.
Low‐Temperature Fast Production of Carbon and Acetic Acid Dual‐Promoted Pd/C Catalysts
Authors: Yao Xiuchao , Ni Lin , Yu Chang , Zhang Mengdi , Wei Qianbing , Huang Huawei , Guo Wei , Huang Hongling , Chang Jiangwei , Qiu Jieshan 
Published: August 2019

AbstractThe Pd/C catalysts are widely used in synthesis of fine chemicals in industry, but their production suffers from a complicated two‐step process involving impregnation and reduction, and requires large amounts of solvents and reductant, which would lead to a series of issues such as time consumption, resource waste and environmental pollution. Herein, ultra‐small Pd nanoparticles uniformly anchored on carbon nanotubes (Pd/CNTs) were synthesized by using a one‐pot and low‐temperature reduction strategy. The present process/technology is very sensitive to and controlled by the supports and solvents, and the carbon support and acetic acid synergistically play crucial and decisive roles in the fast production of Pd/C catalysts. Also, the used solvents can be recycled and reutilized, which meets the requirements of sustainable chemistry and green economy. When the as‐obtained Pd/CNTs catalyst was used to catalyze the oxidation of benzyl alcohol to benzaldehyde, it achieved a conversion efficiency as high as 99.3 % and a high selectivity up to >99.9 %. The simple, scalable and environmentally friendly strategy can be extended to anchor Pd nanoparticles on various carbon substrates, which sheds a new light on the synthesis of Pd/C catalysts.
Transient Phosphenium and Arsenium Ions versus Stable Stibenium and Bismuthenium Ions
Authors: Olaru Marian , Duvinage Daniel , Lork Enno , Mebs Stefan , Beckmann Jens 
Published: August 2019

AbstractFluoride abstraction from bis‐m‐terphenylelement fluorides (2,6‐Mes2C6H3)2EF (E=P, As) generated the highly reactive phosphenium ion [(2,6‐Mes2C6H3)2P]+ and the arsenium ion [(2,6‐Mes2C6H3)2As]+, which immediately underwent intramolecular electrophilic substitution and formation of an 1,2,4‐trimethyl‐6‐mesityl‐5‐m‐terphenyl‐benzo[b]phospholium ion and an 1,2,4‐trimethyl‐6‐mesityl‐5‐m‐terphenyl‐benzo[b]arsolium ion, respectively. The formation of the latter involved a methyl group migration from the ortho‐position of a flanking mesityl group to the meta‐position. This reactivity of [(2,6‐Mes2C6H3)2E]+ (E=P, As) is in sharp contrast to the related stibenium ion [(2,6‐Mes2C6H3)2Sb]+ and bismuthenium ion [(2,6‐Mes2C6H3)2Bi]+, which have been recently isolated and fully characterized (Angew. Chem. Int. Ed. 2018, 57, 10080–10084). On the basis of DFT calculations, a mechanism for the rearrangement of the phosphenium and arsenium ions into the phospholium and arsolium ions is proposed, which is not feasible for the stibenium and bismuthenium ions.
The Plasticity of the Carbohydrate Recognition Domain Dictates the Exquisite Mechanism of Binding of Human Macrophage Galactose‐Type Lectin
Authors: Diniz Ana , Coelho Helena , Dias Jorge S. , van Vliet Sandra J. , Jiménez‐Barbero Jesús , Corzana Francisco , Cabrita Eurico J. , Marcelo Filipa 
Published: August 2019

AbstractThe human macrophage galactose‐type lectin (MGL), expressed on macrophages and dendritic cells (DCs), modulates distinct immune cell responses by recognizing N‐acetylgalactosamine (GalNAc) containing structures present on pathogens, self‐glycoproteins, and tumor cells. Herein, NMR spectroscopy and molecular dynamics (MD) simulations were used to investigate the structural preferences of MGL against different GalNAc‐containing structures derived from the blood group A antigen, the Forssman antigen, and the GM2 glycolipid. NMR spectroscopic analysis of the MGL carbohydrate recognition domain (MGL‐CRD, C181‐H316) in the absence and presence of methyl α‐GalNAc (α‐MeGalNAc), a simple monosaccharide, shows that the MGL‐CRD is highly dynamic and its structure is strongly altered upon ligand binding. This plasticity of the MGL‐CRD structure explains the ability of MGL to accommodate different GalNAc‐containing molecules. However, key differences are observed in the recognition process depending on whether the GalNAc is part of the blood group A antigen, the Forssman antigen, or GM2‐derived structures. These results are in accordance with molecular dynamics simulations that suggest the existence of a distinct MGL binding mechanism depending on the context of GalNAc moiety presentation. These results afford new perspectives for the rational design of GalNAc modifications that fine tune MGL immune responses in distinct biological contexts, especially in malignancy.
Insights into the Electrochemical Polymerization of [Mo3S13]2− Generating Amorphous Molybdenum Sulfide
Authors: Duong Tuan M. , Nguyen Phuc D. , Nguyen Anh D. , Le Ly T. , Nguyen Loan T. , Pham Hai V. , Tran Phong D. 
Published: August 2019

AbstractAmorphous molybdenum sulfide is an attractive electrode material for Li/Mg batteries and an efficient Pt‐free catalyst for the hydrogen evolution reaction in water. By using the electrochemical quartz crystal microbalance (EQCM) analysis, new insights were gained into the electrochemical polymerization of the [Mo3S13]2− cluster, which generates amorphous molybdenum sulfide thin films. In this work, it is shown that, at the anodic potential, a two‐electron oxidative elimination of the terminal disulfide ligand within the [Mo3S13]2− cluster induces the polymerization. A reductive elimination of the terminal disulfide ligand also occurs at the cathodic potential, inducing the polymerization. However, in sharp contrast to the anodic polymerization, according to which the film growth is rapid, the cathodic polymerization competes with the electrochemical reductive corrosion of the readily grown film, therefore occurring at a significant lower growth rate.
Structural and Mechanistic Insights into CO2 Activation by Nitrogenase Iron Protein
Authors: Rettberg Lee A. , Stiebritz Martin T. , Kang Wonchull , Lee Chi Chung , Ribbe Markus W. , Hu Yilin 
Published: August 2019

AbstractThe Fe protein of nitrogenase catalyzes the ambient reduction of CO2 when its cluster is present in the all‐ferrous, [Fe4S4]0 oxidation state. Here, we report a combined structural and theoretical study that probes the unique reactivity of the all‐ferrous Fe protein toward CO2. Structural comparisons of the Azotobacter vinelandii Fe protein in the [Fe4S4]0 and [Fe4S4]+ states point to a possible asymmetric functionality of a highly conserved Arg pair in CO2 binding and reduction. Density functional theory (DFT) calculations provide further support for the asymmetric coordination of O by the “proximal” Arg and binding of C to a unique Fe atom of the all‐ferrous cluster, followed by donation of protons by the proximate guanidinium group of Arg that eventually results in the scission of a C−O bond. These results provide important mechanistic and structural insights into CO2 activation by a surface‐exposed, scaffold‐held [Fe4S4] cluster.
A Tetra‐Porphyrin Host Exhibiting Interannular Cooperativity
Authors: Murphy Rhys B. , Pham Duc‐Truc , Johnston Martin R. 
Published: August 2019

AbstractRecently identified as another form of cooperativity, interannular cooperativity is rarely observed in supramolecular chemistry. A tetra‐porphyrin molecular tweezer with two bis‐porphyrin binding sites is reported that exhibits archetypal interannular cooperativity when complexing 1,4‐diazabicyclo[2.2.2]octane (DABCO). The UV/Vis titration data best supported a 1:2 plus 2:2 plus 1:4 complexation model (host:guest), giving K12=6.32×1013 m−2, K22=3.04×1020 m−3, and K14=1.92×1016 m−4 in CHCl3. The NMR titration data supported the formation of two sandwich species, including tetra‐porphyrin⋅(DABCO)2 as the major species, although there are speciation differences between UV/Vis and NMR concentrations. Using statistical analysis, interannular cooperativity (γ) for tetra‐porphyrin⋅(DABCO)2 was determined to be negative (γ=2.41×10−3), which may be explained by DABCO being too small to be optimally bound simultaneously at both bis‐porphyrin binding sites.
Vinyl Triflate–Aldehyde Reductive Coupling–Redox Isomerization Mediated by Formate: Rhodium‐Catalyzed Ketone Synthesis in the Absence of Stoichiometric Metals
Authors: Shuler William G. , Swyka Robert A. , Schempp Tabitha T. , Spinello Brian J. , Krische Michael J. 
Published: August 2019

AbstractDirect conversion of aldehydes to ketones is achieved via rhodium‐catalyzed vinyl triflate‐aldehyde reductive coupling‐redox isomerization mediated by potassium formate. This method circumvents premetalated C‐nucleophiles and discrete redox manipulations typically required to form ketones from aldehydes.
Phosphinoboration of Diazobenzene: Intramolecular FLP Synthon for PN2B‐Derived Heterocycles
Authors: LaFortune James H. W. , Trofimova Alina , Cummings Haley , Westcott Stephen A. , Stephan Douglas W. 
Published: August 2019

AbstractPhosphinoboration of diazobenzene with Ph2PBR′2 cleanly affords products of the form Ph2P(PhNNPh)BR′2 (2: R′2=catechol, cat; 4: R′2=phenanthrenediol, quin) and shows evidence of Ph2P(PhNNPh)Bpin 7 (pin: pinacol). The mechanism of these reactions was probed computationally and shown to proceed via intermediates involving a diazobenzene‐adduct of the boron center of the PB reagent. The resulting PNNB species 2 and 4 are shown to be frustrated Lewis pairs (FLPs). Despite the presence of weakly Lewis acidic boron centers, these species react with diazobenzene. Additionally, the FLP reactivity of 2 was further probed with 4‐phenyl‐1,2,4‐triazole‐3,5‐dione, 1,10‐phenanthroline‐5,6‐dione, and benzyl azide to give unique five‐, six‐, and eight‐membered heterocyclic rings. Thus, phosphinoboration provides a new avenue to FLPs in which donor and acceptor sites are linked by nitrogen atoms.
Color effect of light sources on peridot based on CIE1976 L*a*b* color system and round RGB diagram system
Authors: Tang Jun , Guo Ying , Xu Chang 
Published: August 2019

AbstractPrevious research indicated that the peridot's color is dominated by the selective absorption of visible light caused by ferrous ion, the hue angle of which is in an inverse ratio of the concentration of Fe2+. This article focuses on the color effect of peridot under different standard light sources based on the CIE1976 L*a*b* color space system and round RGB diagram system and tries to find the best one for its grading and display. Based on the results of a series of experiments, including electron microprobe analysis, spectrophotometer, UV‐Vis spectrum, standard illumination box, and Munsell neutral color chips, it was suggested that the spectral power distribution and color temperature of a standard light source significantly influence the color of peridot in terms of lightness and chroma, particularly in the hue of peridot. As for color grading and displaying of peridot, standard light source A fails to fit in, and the color of peridot under a fluorescent light source has a higher chroma but a lower hue angle than that under daylight light source. The best choice for grading and displaying peridot is the standard light source D65. It is better to distinguish the hue of peridot when it is calculated by the round RGB diagram system.
Identification of the Polaron Measure I: Fixed Coupling Regime and the Central Limit Theorem for Large Times
Authors: Mukherjee Chiranjib , Varadhan S. R. S. 
Published: August 2019

AbstractWe consider the Fröhlich model of the polaron, whose path integral formulation leads to the transformed path measureurn:x-wiley:15347710:media:cpa21858:cpa21858-math-0001with respect to ℙ that governs the law of the increments of the three‐dimensional Brownian motion on a finite interval [−T, T], and Zα, T is the partition function or the normalizing constant and α > 0 is a constant, or the coupling parameter. The polaron measure reflects a self‐attractive interaction. According to a conjecture of Pekar that was proved in [9],
urn:x-wiley:15347710:media:cpa21858:cpa21858-math-0002
exists and has a variational formula. In this article we show that when α > 0 is either sufficiently small or sufficiently large, the limit exists, which is also identified explicitly. As a corollary, we deduce the central limit theorem for
urn:x-wiley:15347710:media:cpa21858:cpa21858-math-0003
under and obtain an expression for the limiting variance. © 2019 the Authors. Communications on Pure and Applied Mathematics is published by the Courant Institute of Mathematical Sciences and Wiley Periodicals, LLC.
Naproxen and Its Phototransformation Products: Persistence and Ecotoxicity to Toad Tadpoles (Anaxyrus terrestris), Individually and in Mixtures
Authors: Cory Wendy  C. , Welch Allison M. , Ramirez Jessica N. , Rein Luke C. 
Published: August 2019

Abstract
Although pharmaceutical pollution is a global environmental concern, much remains unknown about the transformation of pharmaceuticals in the wild and their effects on wildlife. In the environment, pharmaceuticals typically transform to some extent into different, structurally related compounds. Pharmaceutical transformation products resulting from exposure to sunlight (i.e., ultraviolet radiation) in surface waters are of particular concern; these products can be more hydrophobic, persistent, and toxic than their parent compounds. In the present study, naproxen, a widely used nonsteroidal anti-inflammatory drug, and its phototransformation products were studied to assess the overall persistence and photochemical fate of naproxen. Southern toad (Anaxyrus terrestris) larvae were used as model aquatic vertebrates to evaluate the acute toxicity of naproxen and its phototransformation products singly and in mixtures. The phototransformation products were observed to be more persistent and more toxic than naproxen itself. The slower phototransformation of the phototransformation products relative to naproxen suggests a greater potential to accumulate in the environment, particularly when naproxen is continually released. Mixtures of naproxen and its phototransformation products, in ratios observed during phototransformation, were more toxic than naproxen alone, as predicted by the model of concentration addition and the greater toxicity of the phototransformation products. Together, these results indicate that the ecological risk of naproxen may be underestimated by considering environmental levels of naproxen alone. Environ Toxicol Chem 2019;38:2008–2019. © 2019 SETAC.
Abstract
Phototransformation of naproxen generates transformation products of higher persistence and greater ecotoxicity to amphibian tadpoles. NAP-PT1 = 1-(6-methoxy-2-naphthyl)ethanol; NAP-PT2 = 2-acetyl-6-methoxynaphthalene.
The Toxicity of Nonaged and Aged Coated Silver Nanoparticles to Freshwater Alga Raphidocelis subcapitata
Authors: Lekamge Sam , Miranda Ana F. , Trestrail Charlene , Pham Ben , Ball Andrew S. , Shukla Ravi , Nugegoda Dayanthi 
Published: August 2019

Abstract
The transformation of coated silver nanoparticles (AgNPs) and their impacts on aquatic organisms require further study. The present study investigated the role of aging on the transformation of differently coated AgNPs and their sublethal effects on the freshwater alga Raphidocelis subcapitata. The stability of AgNPs was evaluated over 32 d, and the results indicated that transformation of AgNPs occurred during the incubation; however, coating-specific effects were observed. Fresh AgNPs increased reactive oxygen species (ROS) formation, whereas aged AgNPs induced excessive ROS generation compared with their fresh counterparts. Increased ROS levels caused increased lipid peroxidation (LPO) in treatment groups exposed to both fresh and aged NPs, although LPO was comparatively higher in algae exposed to aged AgNPs. The observed increase in catalase (CAT) activity of algal cells was attributed to early stress responses induced by excessive intracellular ROS generation, and CAT levels were higher in the aged NP treatment groups. In conclusion, AgNPs increased ROS levels and LPO in algae and caused the activation of antioxidant enzymes such as CAT. Overall, the results suggest that aging and coating of AgNPs have major impacts on AgNP transformation in media and their effects on algae. Environ Toxicol Chem 2019;38:2371–2382. © 2019 SETAC
Effects of grape pomace and seed polyphenol extracts on the recovery of gut microbiota after antibiotic treatment in high‐fat diet‐fed mice
Authors: Lu Feng , Liu Fengjiao , Zhou Qian , Hu Xiaosong , Zhang Yan 
Published: August 2019

AbstractThe widespread use of antibiotics all over the world increases the risk of many metabolic diseases by altering the gut microbiota. Grape by‐products are of particular interest in the prevention of metabolic diseases, while only minimum amounts of these wastes are up‐graded or recycled at present. The study investigated the effect of grape pomace (GPE) and seed (GSE) polyphenol extracts on the recovery of gut microbiota after antibiotic cocktail treatment in high‐fat diet‐fed (HFD) mice. C57BL/6J mice were fed HFD together with antibiotic treatment by drinking water for 3 weeks. Then, GPE and GSE were supplemented for 7 days after withdrawal of antibiotics. The gut microbiota was characterized by a significant loss of diversity and certain important taxon after a 3‐week antibiotic cocktail treatment. The GPE and GSE supplementation during the restore period of gut microbiota had some positive effects. The relative abundance of gut microbiota was improved by GPE and GSE compared to the spontaneous recovery group. And gut microbiota diversity was also greatly changed by GPE and GSE, being indicated by the changes of Verrucomicrobia and Akkermansia in feces. These findings suggested that grape polyphenol extracts have a great influence on the recovery of gut microbiota after antibiotics and high‐fat diet treatment.
Volatile components and nutritional qualities of Viscum articulatum Burm.f. parasitic on ancient tea trees
Authors: Wang Qiushuang , Chen Dong , Zhang Qianwen , Qin Dandan , Jiang Xiaohui , Li Hongjian , Fang Kaixing , Cao Junxi , Wu Hualing 
Published: August 2019

AbstractVolatile flavor compounds (VFCs) and nutrients in Viscum articulatum Burm.f. parasitic on ancient tea trees (named TM) were studied in this research by headspace solid‐phase microextraction (HS‐SPME)/gas chromatography–mass spectrometry (GC–MS) and conventional methods. Sixty‐six volatile compounds belonging to different classes were identified by GC–MS. The ketones, alcohols, and aldehydes were the principal aroma groups in TM according to principle component analysis (PCA). The most abundant aroma components in TM included benzaldehyde (9.64%), geranylacetone (7.92%), epoxy‐β‐ionone (7.71%), β‐linalool (7.35%), methyl salicylate (6.96%), and hotrienol (6.14%), significantly higher than CKs (p < .05). The positive PC1 and PC2 in TM were correlated with benzaldehyde, hotrienol, methyl salicylate, and geranylacetone. The mistletoes could be differentiated from CKs due to the difference in aroma compounds. Clean and fresh, woody and nutty odor with minor floral scent was the characteristics of TM. Analysis of the nutritional components showed that contents of polyphenols and catechins in TM were at trace levels, significantly lower than CKs (p < .05). The total contents of polyphenols, amino acids, carbohydrates, and caffeine in TM were significantly lower from the total soluble solids (p < .05), indicating that there were still lots of compounds undetected in TM. The sensory test showed that the taste and aroma in TM can be accepted, which indicates TM could be developed into alternative tea drinks in the future.