bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pulsradiolytische Untersuchung schneller Reaktionen von hydratisierten Elektronen, freien Radikalen und Ionen mit Tetranitromethan in wäßriger Lösung
Authors: Asmus K.‐D. , Henglein A. , Ebert M. , Keene J. P. 
Published: April 2015

AbstractDie absoluten bimolekularen Geschwindigkeitskonstanten der Reaktionen des Tetranitromethans mit hydratisierten Elektronen, Wasserstoffatomen, verschiedenen Alkoholradikalen und mit den Ionen O2−, CH3COCH3− und Cu+ wurden bestimmt. Ferner wird ein Verfahren beschrieben, um Tetranitromethan als „Indikator”︁ für freie Radikale, die keine starke Lichtabsorption besitzen, zu verwenden. Auf diese Weise wurde die Reaktion OH + CH3OH → H2O + CH2OH untersucht.Alle Reaktionen des Tetranitromethans sind sehr schnell und werden im wesentlichen durch die Diffusion der Reaktanden kontrolliert. Die Bildung des aci‐Nitroforms bei diesen Reaktionen wird auf die Übertragung eines Elektrons von dem Reaktionspartner auf das Tetranitromethan mit sofortiger Dissoziation des negativen Molekelions zurückgeführt. Freie neutrale Radikale übertragen etwa gleich schnell wie negative Radikalionen, während die Übertragung vom Cu+‐Ion langsamer geschieht.Für die Reaktion des OH‐Radikals mit Methanol wurde eine überraschend hohe Geschwindigkeitskonstante von mehr als 3 · 109 Mol−1 1 sec−1 gefunden; auch dieser Prozeß scheint demnach weitgehend durch die Diffusion der Reaktionspartner bestimmt zu sein.
Über magnetische Kernresonanzspektren wäßriger Brenztraubensäurelösungen
Authors: Becker M. 
Published: April 2015

AbstractZur Aufklärung der Keto‐Enol‐Tautometrie der Brenztraubensäure, über welche in der Literatur wider‐sprechende Angaben zu finden sind, werden Kernresonanzspektren von der Brenztraubensäure und von Brenztraubensäure‐Wasser‐Mischungen aufgenommen, wobei als Eichsubstanz für die Linienintensität 1,4‐Dioxan verwendet wird. Die wasserfreie Brenztraubensäure besteht aus der Ketoform; ein etwaiger Enolgehalt liegt unter 2%. In wäßriger Lösung existiert ein ringförmiges Gleichgewicht zwischen der Ketoform, der durch Wasseraufnahme daraus entstehenden 2,2‐Dihydroxypropionsäure und den Anionen dieser Säuren. Die Dissoziationskonstante der Ketoform beträgt 0,86 · 10−2 mol · l−1, die der 2,2‐Dihydroxypropionsäure 2,5 · 10−4 mol · l−1. Aus der Temperaturabhängigkeit des Gleichgewichtes wird die Reaktions‐enthalpie und ‐entropie der Reaktion CH2COCOOH + H2O → CH3C(OH)2COOH ermittelt. Diese Reaktion wird durch Hydroniumionen katalysiert. In stark saurer Lösung läßt sich aus der Linienverbreiterung die Zerfallsgeschwindigkeitskonstante der 2,2‐Dihydroxypropionsäure bestimmen.
Die chemische Grundlage der Vererbung, der genetische Code
Authors: Ochoa Severo 
Published: April 2015

AbstractIn the cell the genetic information contained in a molecule of DNA is transferred to messenger RNA, which in turn acts as a template in the synthesis of protein. The nucleotide sequence in DNA is mirrored as a corresponding nucleotide sequence in the messenger RNA, the latter then determining the primary structure of the proteins (i.e. their amino acid sequence). In this way the language of the nucleic acids, which comprises four letters (the four nucleotide bases), is translated into that of the proteins, which comprises 20 letters (the 20 amino acids). It is supposed that each group of three consecutive nucleotide bases in the template RNA determines an amino acid. Hence the genetic code is a “triplet” code.Polyribonucleotides, which can be synthesized readily from the ribonucleoside‐5′‐diphosphates with the help of the enzyme polynucleotide phosphorylase, can replace natural template RNA in a cell‐free system similar to that used in protein synthesis in which the amino acids are polymerised into polypeptide chains. Since the nature of the amino acids incorporated into the polypeptide chains depends on the base composition of the synthetic polynucleotide, it has been possible to discover the base compositions of a number of the triplets corresponding to the various amino acids. In the Escherichia coli system homopolynucleotides such as polyadenylic acid, polycytidylic acid and polyuridylic acid lead to the incorporation of lysine, proline and phenylalanine. Under these conditions polysine, polyproline and polyphenylalanine, respectively, are formed. Copolynucleotides, which contain two or more different nucleotide bases, direct several different amino acids into the polypeptide chain; for example, polypeptides made in the presence of polyadenylocytidylic acid contain lysine, isoleucine, asparagine, leucine, tyrosine and phenylalanine.A correlation has been made between the base compositions of the individual synthetic polynucleotides which were added to the cell‐free E. coli system and the nature and quantity of the amino acids incorporated into the polypeptide chain. In this way the base compositions of 46 of the 68 possible triplets of template RNA, corresponding to the 20 amino acids, have so far been established. Probably all the “meaningful” triplets are not yet known. In some instances it is found that a certain amino acid is coded for by several different triplets; a code with such a property is termed a “degenerate” code. With few exceptions, the actual sequence of bases within a given triplet is not at present known; only the base composition has been determined. There are indications that the genetic code is universal or, in other words, that there is only one code for all forms of life.
Über die Codierung der Proteinstruktur in Gegenwart von Proflavin
Authors: Braunitzer G. 
Published: April 2015

AbstractEs wird die Vermehrung eines einsträngigen DNS‐Phagens (fd) ohne und nach Zusatz von Proflavin untersucht. Verglichen werden die Kurven der Verteilung der biologischen Aktivität in der trägerfreien Elektrophorese der entsprechenden Ansätze, wodurch polare Änderungen im Hüllprotein erfaßt werden. Die Versuche wurden in zwei Serien, im Dunkel und in Gegenwart von Licht durchgeführt.
Hydration of Haemoglobin and its Reversible Oxygenation
Authors: Maričić S. , Pifat Greta , Pravdić V. 
Published: April 2015

AbstractElectrical conductivity measurements were done on samples of solid bovine methaemoglobin of various hydration states. The energies of activation calculated from these data, are discussed with regard to Rosenberg's theory. The lowest value of the activation energy (observed at 35% hydration) corresponds to that of pure water.Using spectrophotometric techniques the interaction of “chromohaemoglobin” (“anhydrohaemoglobin” after Haurowitz) with oxygen was followed in situ. The importance of the shell of hydration for the reversible oxygenation is discussed and a new hypothesis advanced.
Elektrophoretische Untersuchungen an Nukleohistonen
Authors: Olivera Baldomero M. , Huang Ru Chih , Davidson Norman 
Published: April 2015

AbstractEs wird über elektrophoretische Untersuchungen an rekonstituierten Nukleohistonen, nativen Nukleohistonen und Chromatin in homogener wäßriger Lösung berichtet. Die Messungen wurden unter den folgenden Bedingungen ausgeführt: 0,01 M NaCl, 0,001 M Trispuffer, pH = 7,5, 0°C. Diese Nukleoproteine sind negativ geladen, aber ihre elektrophoretischen Beweglichkeiten sind geringer als die der nativen DNS. Die Beweglichkeiten rekonstituierter Nukleohistone nehmen mit steigendem Histon‐zu‐DNS‐Verhältnis ab. Für vollständig komplexgebundenes Nukleohiston (Molzahl DNS Phosphat ist gleich Molzahl basischer Aminosäuren im Histon) erhält man die folgenden Beweglichkeitswerte für Nukleohiston Ib, IIb, III und IV: 1,30,1,50,1,97, und 197 · 10−4 cm2 Volt−1 sec−1 (DNS = 2,17 · 10−4). Es wird nur eine teilweise Übereinstimmung der änderung der Beweglichkeiten mit der Anderung des sauren Aminosäuregehalts der Histone festgestellt. In einer Mischung von Nukleohiston IIb und DNS bewegen sich die beiden Komponenten unabhängig voneinander; in einer Mischung von Nukleohiston Ib und DNS findet man elektrophoretisch nur eine Komponente, deren Beweglichkeit zwischen denen der Ausgangskomponenten liegt. Aus verschiedenen Geweben der Erbse gewonnene Chromatine besitzen unterschiedliche Beweglichkeiten. Dieser Befund hängt möglicherweise mit ihrer biologischen Aktivität zusammen. Jedes einzelne Chromatin ist elektrophoretisch hinreichend homogen. Damit ist gezeigt, daß seine verschiedenen Komponenten alle zu einer elektrophoretischen Einheit zusammengebunden sind.
Biophysical probing of the binding properties of a Cu(II) complex with G‐quadruplex DNA: an experimental and computational study
Authors: Housaindokht Mohammad Reza , Verdian‐Doghaei Asma 
Published: April 2015

AbstractTelomerase inhibition through G‐quadruplex stabilization by small molecules is of great interest as a novel anticancer therapeutic strategy. Here, we show that newly synthesized Cu‐complex binds to G‐quadruplex DNA and induces changes in its stability. This biophysical interaction was investigated in vitro using spectroscopic, voltammetric and computational techniques. The binding constant for this complex to G‐quadruplex using spectroscopic and electrochemical methods is in the order of 105. The binding stoichiometry was investigated using spectroscopic techniques and corresponded to a ratio of 1: 1. Fluorescence titration results reveal that Cu‐complex is quenched in the presence of G‐quadruplex DNA. Analysis of the fluorescence emission at different temperatures shows that ΔH° > 0, ΔS° > 0 and ΔG° < 0, and indicates that hydrophobic interactions played a major role in the binding processes. MD simulation results suggested that this ligand could stabilize the G‐quadruplex structure. An optimized docked model of the G‐quadruplex–ligand mixture confirmed the experimental results. Based on the results, we conclude that Cu‐complex as an anticancer candidate can bind and stabilize the G‐quadruplex DNA structure. Copyright © 2015 John Wiley & Sons, Ltd.
GreedExCol, A CSCL tool for experimenting with greedy algorithms
Authors: Debdi Ouafae , Paredes‐Velasco Maximiliano , Velázquez‐Iturbide J.Ángel 
Published: April 2015

ABSTRACTCosts and benefits are recurrent issues that concern all the computing areas, including computer and software engineering. Mastery of optimization algorithms is essential in these fields, but their didactics hardly has received any attention. To fill this gap, the interactive system GreedEx was designed to support the active learning of greedy algorithms by means of experimentation. In this article we describe GreedExCol, a collaborative extension of GreedEx that complements its experimental phase with a discussion phase held by the students in each team. The contributions of the article are threefold. Firstly, we present GreedExCol, a CSCL system aimed at supporting collaborative discussion on experimental results of optimality for greedy algorithms. Secondly, GreedExCol was evaluated with respect to educational effectiveness, obtaining statistically significant improvements of the collaborative, experimental approach over an individual, experimental approach without the support of GreedExCol. Thirdly, GreedExCol was evaluated in the same two groups with respect to motivation, obtaining a statistically significant increase of implicit motivation for students in the experimental group. Overall, we present a medium‐term effort for developing an innovative learning system and a comprehensive evaluation of its impact over the students. © 2015 Wiley Periodicals, Inc. Comput. Appl. Eng. Educ. Comput Appl Eng Educ 23:790–804, 2015; View this article online at wileyonlinelibrary.com/journal/cae; DOI 10.1002/cae.21655
Comparative methylome analysis in solid tumors reveals aberrant methylation at chromosome 6p in nasopharyngeal carcinoma
Authors: Dai Wei , Cheung Arthur Kwok Leung , Ko Josephine Mun Yee , Cheng Yue , Zheng Hong , Ngan Roger Kai Cheong , Ng Wai Tong , Lee Anne Wing Mui , Yau Chun Chung , Lee Victor Ho Fu , Lung Maria Li 
Published: April 2015

AbstractAltered patterns of DNA methylation are key features of cancer. Nasopharyngeal carcinoma (NPC) has the highest incidence in Southern China. Aberrant methylation at the promoter region of tumor suppressors is frequently reported in NPC; however, genome‐wide methylation changes have not been comprehensively investigated. Therefore, we systematically analyzed methylome data in 25 primary NPC tumors and nontumor counterparts using a high‐throughput approach with the Illumina HumanMethylation450 BeadChip. Comparatively, we examined the methylome data of 11 types of solid tumors collected by The Cancer Genome Atlas (TCGA). In NPC, the hypermethylation pattern was more dominant than hypomethylation and the majority of de novo methylated loci were within or close to CpG islands in tumors. The comparative methylome analysis reveals hypermethylation at chromosome 6p21.3 frequently occurred in NPC (false discovery rate; FDR=1.33 × 10−9), but was less obvious in other types of solid tumors except for prostate and Epstein–Barr virus (EBV)‐positive gastric cancer (FDR<10−3). Bisulfite pyrosequencing results further confirmed the aberrant methylation at 6p in an additional patient cohort. Evident enrichment of the repressive mark H3K27me3 and active mark H3K4me3 derived from human embryonic stem cells were found at these regions, indicating both DNA methylation and histone modification function together, leading to epigenetic deregulation in NPC. Our study highlights the importance of epigenetic deregulation in NPC. Polycomb Complex 2 (PRC2), responsible for H3K27 trimethylation, is a promising therapeutic target. A key genomic region on 6p with aberrant methylation was identified. This region contains several important genes having potential use as biomarkers for NPC detection.
Efficient Biosynthesis of Ethyl (R)‐3‐Hydroxyglutarate through a One‐Pot Bienzymatic Cascade of Halohydrin Dehalogenase and Nitrilase
Authors: Yao Peiyuan , Wang Lei , Yuan Jing , Cheng Lihua , Jia Rongrong , Xie Meixian , Feng Jinhui , Wang Min , Wu Qiaqing , Zhu Dunming 
Published: April 2015

AbstractThe front cover artwork for Issue 09/2015 is provided by the Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences (P.R. China), the Tianjin University of Science & Technology (P.R. China), and Hebei Chengxin Co., Ltd (P.R. China). The image shows two one‐pot processes for the bienzymatic synthesis of ethyl (R)‐3‐hydroxyglutarate (EHG), a key intermediate for the synthesis of rosuvastatin, from ethyl (S)‐4‐chloro‐3‐hydroxybutyrate (ECHB). See the Full Paper itself at http://dx.doi.org/10.1002/cctc.201500061.
Anforderungen der zukunftsorientierten Spezialchemie an die angewandte Reaktionstechnik
Authors: Wachsen Olaf , Bacher Vanessa , Geisbauer Andreas , Appel Jörg , Niebuhr Verena , Lade Oliver 
Published: April 2015

AbstractDie Menschheit steht gegenwärtig vor enormen ökonomischen, ökologischen und sozialen Herausforderungen. Die Spezialchemie leistet mit ihren bereits langjährig etablierten und mit innovativen Produkten einen entscheidenden Beitrag zur Bewältigung dieser Megatrends. Daraus abgeleitet ergeben sich die zukünftigen Anforderungen an die angewandte chemische Reaktionstechnik. Sowohl bewährte als auch neue Methoden werden benötigt, um im interdisziplinären Umfeld zwischen Chemie, Physik, Biologie und Ingenieurwissenschaften erfolgreiche Beiträge liefern zu können.
Input variable selection for an inferential predictor using the retrospective Taguchi method
Authors: Rahman M. Musfiqur , Imtiaz Syed Ahmad , Hawboldt Kelly , Zhang Yan 
Published: April 2015

AbstractA systematic method based on Taguchi's experimental design approach is proposed for selecting input variables for an inferential predictor. Several implementation difficulties arising from dynamic variation and correlation among process variables are addressed. The predictor is developed using support vector regression (SVR) in order to capture the nonlinearity in the process. The prediction performance of the proposed Taguchi‐SVR is compared with the existing variable importance in projection (VIP)'SVR method. The industrial case study clearly indicates that the proposed methodology can be a valuable tool for process variable selection and it can improve the prediction performance of the inferential predictor.
5‐year follow‐up of a randomized controlled trial of immediate versus delayed zoledronic acid for the prevention of bone loss in postmenopausal women with breast cancer starting letrozole after tamoxifen: N03CC (Alliance) trial
Authors: Wagner‐Johnston Nina D. , Sloan Jeff A. , Liu Heshan , Kearns Ann E. , Hines Stephanie L. , Puttabasavaiah Suneetha , Dakhil Shaker R. , Lafky Jacqueline M. , Perez Edith A. , Loprinzi Charles L. 
Published: April 2015

BACKGROUNDPostmenopausal women with breast cancer receiving aromatase inhibitors are at an increased risk of bone loss. The current study was undertaken to determine whether upfront versus delayed treatment with zoledronic acid (ZA) impacted bone loss. This report described the 5‐year follow‐up results.METHODSA total of 551 postmenopausal women with breast cancer who completed tamoxifen treatment and were undergoing daily letrozole treatment were randomized to either upfront (274 patients) or delayed (277 patients) ZA at a dose of 4 mg intravenously every 6 months. In the patients on the delayed treatment arm, ZA was initiated for a postbaseline bone mineral density T‐score of <‐2.0 or fracture.RESULTSThe incidence of a 5% decrease in the total lumbar spine bone mineral density at 5 years was 10.2% in the upfront treatment arm versus 41.2% in the delayed treatment arm (P<.0001). A total of 41 patients in the delayed treatment arm were eventually started on ZA. With the exception of increased NCI Common Toxicity Criteria (CTC) grade 1/2 elevated creatinine and fever in the patients treated on the upfront arm and cerebrovascular ischemia among those in the delayed treatment arm, there were no significant differences observed between arms with respect to the most common adverse events of arthralgia and back pain. Osteoporosis occurred less frequently in the upfront treatment arm (2 vs 8 cumulative cases), although this difference was not found to be statistically significant. Bone fractures occurred in 24 patients in the upfront treatment arm versus 25 patients in the delayed treatment arm.CONCLUSIONSImmediate treatment with ZA prevented bone loss compared with delayed treatment in postmenopausal women receiving letrozole and these differences were maintained at 5 years. The incidence of osteoporosis or fractures was not found to be significantly different between treatment arms. Cancer 2015;121:2537–2543. © 2015 American Cancer Society.
Vacancy‐Free Prussian Blue Nanocrystals with High Capacity and Superior Cyclability for Aqueous Sodium‐Ion Batteries
Authors: Wu Xianyong , Sun Mengying , Guo Simin , Qian Jiangfeng , Liu Yong , Cao Yuliang , Ai Xinping , Yang Hanxi 
Published: April 2015

AbstractAqueous Na‐ion batteries have the competitive advantages of being low costing and possessing inherent safety, and they are particularly suitable for large‐scale energy‐storage applications. However, the development of this new battery system is hindered by the lack of suitable Na hosts with sufficiently high capacity and cycle life. Herein, we report vacancy‐free Na2CoFe(CN)6 nanocubes synthesized by a controlled crystallization reaction and reveal their use as a new aqueous cathode with reversible Na‐storage behavior. Owing to its perfect lattice framework with two redox‐active sites, this material exhibits a high reversible capacity of 130 mA h g−1, a strong rate capability at 20 C, and superior cyclability with 90 % capacity retention over 800 cycles, all of which indicate that this material may possibly serve as a high‐performance and long‐life cathode for aqueous Na‐ion batteries. Also, the synthetic strategy described in this work may be extended to a wide range of Prussian blue compounds for the fabrication of well‐shaped nanocubes with few defects for energy storage, catalysis, and other applications.
Kitchen‐Inspired Nanochemistry: Dispersion, Exfoliation, and Hybridization of Functional MoS2 Nanosheets Using Culinary Hydrocolloids
Authors: Ravula Sudhir , Essner Jeremy B. , Baker Gary A. 
Published: April 2015

AbstractAs a two‐dimensional material, molybdenum disulfide (MoS2) has drawn wide attention due to its fascinating properties and exciting application prospects. However, in order to access these properties, which lie within single‐ or few‐layer nanosheets, the inter‐sheet van der Waals interactions within the bulk material must be adequately disrupted to exfoliate MoS2 to atomic thicknesses. The hitch with most current exfoliation methods, though, is that they employ expensive, exotic, or environmentally incompatible methods that suffer poor scalability and poor reproducibility, producing weakly stabilized sheets that retro‐aggregate. These pitfalls render many current approaches unsuitable for the development of large‐scale devices and nanocomposites, thereby making cheaper, more benign alternatives highly sought after. Herein, we present the sonication‐assisted aqueous phase exfoliation of bulk MoS2 into dispersed single‐ or few‐layer nanosheets using popular culinary hydrocolloids, including guar gum (GG), tannic acid (TA), and xanthan gum (XG). These green agents are commercially available, inexpensive, and environmentally friendly substances and act as good dispersing and exfoliating agents. Under optimized exfoliation conditions, dispersed solution concentrations of 0.24, 0.15, and 0.06 mg mL−1 were achieved for MoS2‐GG, MoS2‐TA, and MoS2‐XG, respectively. In addition, the sterically stabilized nanosheets were successfully decorated with gold nanoparticles via an in situ reduction by the hydrocolloids to yield plasmonic nanocomposites exhibiting excellent catalytic activity in 4‐nitrophenol reduction.
Towards Shape Control of Metal Oxide Nanocrystals in Confined Molten Media
Authors: Chen Dennis P. , Fu Jie , Skrabalak Sara E. 
Published: April 2015

AbstractSpray synthesis is a robust route to compositionally complex materials as fine powders; however, the solid‐state synthetic conditions in most cases limit access to discrete nanoparticles with defined structural features. Yet, by maintaining a dynamic droplet phase through integration of molten salt chemistry, product formation can proceed in manners similar to lower temperature solution routes to nanomaterials. This Focus Review connects concepts from classical nucleation theory and molten salt chemistry to provide a framework for nanocrystal formation via aerosol‐assisted molten salt synthesis (AMSS). Examples of metal oxide nanocrystal formation by AMSS are surveyed and highlight how the spatial and temporal confinement of aerosol droplets limits crystal growth in molten media. Ultimately, we strive to provide practical guidelines, not limited to AMSS, towards the synthesis of compositionally complex materials as shape‐defined nanocrystals.
Minimal Graphic Functions on Manifolds of Nonnegative Ricci Curvature
Authors: Ding Qi , Jost Jürgen , Xin Yuanlong 
Published: April 2015

AbstractWe study minimal graphic functions on complete Riemannian manifolds ∑ with nonnegative Ricci curvature, euclidean volume growth, and quadratic curvature decay. We derive global bounds for the gradients for minimal graphic functions of linear growth only on one side. Then we can obtain a Liouville‐type theorem with such growth via splitting for tangent cones of ∑ at infinity. When, in contrast, we do not impose any growth restrictions for minimal graphic functions, we also obtain a Liouville‐type theorem under a certain nonradial Ricci curvature decay condition on ∑. In particular, the borderline for the Ricci curvature decay is sharp by our example in the last section. © 2015 Wiley Periodicals, Inc.