bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role of Hydrogen‐Bonding Acceptors in Organo‐Enamine Catalysis
Authors: Han Junbin , Lu Zhichao , Flach Andrew L. , Paton Robert S. , Hammond Gerald B. , Xu Bo 
Published: July 2015

AbstractA hydrogen bond acceptor plays an important role in the catalytic cycle of organo‐enamine catalysis. It can effectively influence the rate of reaction through hydrogen bonding interaction with enammonium (N‐protonated enamine intermediate). Our findings are supported by both kinetic experiments and quantum chemical calculations.
Chiroptical Studies on Supramolecular Chirality of Molecular Aggregates
Authors: Sato Hisako , Yajima Tomoko , Yamagishi Akihiko 
Published: July 2015

AbstractThe attempts of applying chiroptical spectroscopy to supramolecular chirality are reviewed with a focus on vibrational circular dichroism (VCD). Examples were taken from gels, solids, and monolayers formed by low‐molecular mass weight chiral gelators. Particular attention was paid to a group of gelators with perfluoroalkyl chains. The effects of the helical conformation of the perfluoroalkyl chains on the formation of chiral architectures are reported. It is described how the conformation of a chiral gelator was determined by comparing the experimental and theoretical VCD spectra together with a model proposed for the molecular aggregation in fibrils. The results demonstrate the potential utility of the chiroptical method in analyzing organized chiral aggregates. Chirality 27:659–666, 2015. © 2015 Wiley Periodicals, Inc.
Kurt Gottlob – ein Leben für den Kautschuk
Authors: Röker Klaus‐Dieter 
Published: July 2015

AbstractDer Chemiker Kurt Gottlob (1881–1925) war einer der bekanntesten Kautschuk‐Technologen des frühen 20. Jahrhunderts. Gottlobs Arbeiten deckten nahezu die gesamte Kautschukchemie ab. Kurt Gottlob war eines der wichtigsten und kreativsten Mitglieder im Arbeitskreis um Fritz Hofmann (1866–1956) bei den Farbenfabriken, vorm. Friedr. Bayer, welcher den Methylkautschuk, den weltweit ersten synthetischen Kautschuk, entwickelte. Zusammen mit Fritz Hofmann entdeckte er die organischen Beschleuniger, die den Vulkanisationsprozess des Kautschuks revolutionierten. Mit der Polymerisation von Isopren in Gegenwart von flüssigen kolloidalen Lösungen von Albumin wendete er erstmals das Prinzip der Emulsionspolymerisation an.
Development of Small‐Molecule Cryptochrome Stabilizer Derivatives as Modulators of the Circadian Clock
Authors: Lee Jae Wook , Hirota Tsuyoshi , Kumar Anupriya , Kim Nam‐Jung , Irle Stephan , Kay Steve A. 
Published: July 2015

AbstractSmall‐molecule probes have been playing prominent roles in furthering our understanding of the molecular underpinnings of the circadian clock. We previously discovered a carbazole derivative, KL001 (N‐(3‐(9H‐carbazol‐9‐yl)‐2‐hydroxypropyl)‐N‐(furan‐2‐ylmethyl)methanesulfonamide), as a stabilizer of the clock protein cryptochrome (CRY). Herein we describe an extensive structure–activity relationship analysis of KL001 derivatives leading to the development of a highly active derivative: 2‐(9H‐carbazol‐9‐yl)‐N‐(2‐chloro‐6‐cyanophenyl)acetamide (KL044). Subsequent 3D‐QSAR analysis identified critical features of KL001 derivatives and provided a molecular‐level understanding of their interaction with CRY. The electron‐rich carbazole, amide/hydroxy linker, sulfonyl group, and electron‐withdrawing nitrile moieties contribute to greater biological activity. The hydrogen bonding interactions with Ser394 and His357 as well as stronger CH–π interactions with Trp290 make KL044 a better binder than KL001. KL044 lengthened the circadian period, repressed Per2 activity, and stabilized CRY in reporter assays with roughly tenfold higher potency than KL001. Altogether, KL044 is a powerful chemical tool to control the function of the circadian clock through its action on CRY.
Impact of long‐term tenofovir disoproxil fumarate on incidence of hepatocellular carcinoma in patients with chronic hepatitis B
Authors: Kim W. Ray , Loomba Rohit , Berg Thomas , Aguilar Schall Raul E. , Yee Leland J. , Dinh Phillip V. , Flaherty John F. , Martins Eduardo B. , Therneau Terry M. , Jacobson Ira , Fung Scott , Gurel Selim , Buti Maria , Marcellin Patrick 
Published: July 2015

BACKGROUNDEfficacy trials have shown that antiviral therapy improves the outcomes of patients with chronic hepatitis B virus (HBV) infection. However, prospective data regarding the effect of antiviral therapy on the incidence of hepatocellular carcinoma (HCC), especially among patients without cirrhosis, are limited. The authors examined the impact of tenofovir disoproxil fumarate (TDF) on the incidence of HCC using a validated prediction model.METHODSThe incidence of HCC in patients treated with TDF was obtained in the pivotal TDF registration studies after 384 weeks of follow‐up. The predicted risk of HCC in individual patients was calculated using the Risk Estimation for Hepatocellular Carcinoma in Chronic Hepatitis B (REACH‐B) model, which estimates HCC incidence for up to 10 years based on age, sex, alanine aminotransferase level, hepatitis B e antigen status, and HBV‐DNA. Standardized incidence ratios (SIRs) were calculated comparing the observed and predicted numbers of HCC cases in the study cohort.RESULTSAmong 634 patients with evaluable baseline biopsies, 152 had cirrhosis (Ishak fibrosis score of 5 or 6) and 482 did not. During the 384 weeks of study, 14 cases of HCC were reported, with 4 occurring within the first year. The incidence of HCC was 0.37% per year in the study as a whole (0.28% among patients without cirrhosis and 0.65% among patients with cirrhosis). Among patients without cirrhosis, the observed incidence of HCC was significantly lower than predicted (SIR, 0.40; 95% confidence interval, 0.199‐0.795). The last HCC case in a patient with cirrhosis occurred around week 192 with an SIR of 0.51 (95% confidence interval, 0.231‐1.144) reported at week 384.CONCLUSIONSBased on the REACH‐B risk calculator, long‐term therapy with TDF was associated with a reduced incidence of HCC among patients without cirrhosis who met treatment criteria. Cancer 2015;121:3631–3638. © 2015 American Cancer Society.
Prediction of future hepatocellular carcinoma incidence in moderate to heavy alcohol drinkers with the FIB‐4 liver fibrosis index
Authors: Suh Beomseok , Yun Jae Moon , Park Sehhoon , Shin Dong Wook , Lee Tae Hoon , Yang Hyung‐Kook , Ahn Eunmi , Lee Hyejin , Park Jin Ho , Cho BeLong 
Published: July 2015

BACKGROUNDAlthough heavy alcoholics are at heightened risk for hepatocellular carcinoma (HCC), there are no guidelines that recommend HCC screening for heavy alcoholics. This study investigated FIB‐4, a noninvasive and easily applicable liver fibrosis index, as a risk factor for HCC incidence among alcohol drinkers without viral hepatitis.METHODSThis retrospective cohort study included 6661 generally healthy adults who were 30 years old or older, did not have chronic viral hepatitis, and visited Seoul National University Hospital for a general, routine health evaluation. The future HCC incidence was determined from National Health Insurance medical service claims data (median follow‐up, 6.2 years).RESULTSWith adjustments for age, sex, body mass index, smoking, and alcohol, compared with subjects with FIB‐4 values less 1.00, subjects with FIB‐4 values greater than or equal to 1.75 and less than 2.10 and subjects with FIB‐4 values greater than or equal to 2.10 had adjusted hazard ratios (aHRs) of 5.18 (95% confidence interval [CI], 1.12‐24.00) and 13.63 (95% CI, 3.77‐49.33), respectively, for HCC incidence. This was heightened in subjects who drank more 30 g of alcohol per day: the aHRs were 8.39 (95% CI, 1.28‐54.87) and 16.58 (95% CI, 3.87‐71.04), respectively. FIB‐4 was shown to have a higher predictive value for HCC incidence than ultrasonographically detected liver cirrhosis (C‐index, 0.665 vs 0.527; P = .044).CONCLUSIONSHigh FIB‐4 is a risk factor with a high predictive value for HCC incidence, especially among moderate to heavy alcoholics (>30 g/d). FIB‐4 is a readily available and probably cost‐effective clinical tool with potential value for identifying subpopulations of alcoholics at particularly high risk who would benefit from regular HCC screening. Further investigations are warranted to validate our results; nonetheless, our study suggests that FIB‐4 may be useful in HCC screening among alcoholics. Cancer 2015;121:3818–3825. © 2015 American Cancer Society.
Asymptotic Behavior of the Nonlinear Schrödinger Equation with Harmonic Trapping
Authors: Hani Zaher , Thomann Laurent 
Published: July 2015

AbstractWe consider the cubic nonlinear Schrödinger equation with harmonic trapping on ℝD (1 ≤ D ≤ 5). In the case when all directions but one are trapped (aka “cigar‐shaped trap”), we prove modified scattering and construct modified wave operators for small initial and final data, respectively. The asymptotic behavior turns out to be a rather vigorous departure from linear scattering and is dictated by the resonant system of the NLS equation with full trapping on ℝD−1. In the physical dimension D = 3, this system turns out to be exactly the (CR) equation derived by Faou, Germain, and the first author as the large box limit of the resonant NLS equation in the homogeneous (zero potential) setting. The special dynamics of the latter equation, combined with the above modified scattering results, allow us to justify and extend some physical approximations in the theory of Bose‐Einstein condensates in cigar‐shaped traps.© 2016 Wiley Periodicals, Inc.
Dynamics of Fluorescent Dyes Attached to G‐Quadruplex DNA and their Effect on FRET Experiments
Authors: Søndergaard Siri , Aznauryan Mikayel , Haustrup Emil K. , Schiøtt Birgit , Birkedal Victoria , Corry Ben 
Published: July 2015

AbstractFRET spectroscopy is a promising approach for investigating the dynamics of G‐quadruplex DNA folds and improving the targeting of G‐quadruplexes by potential anticancer compounds. To better interpret such experiments, classical and replica‐exchange molecular dynamics simulations and fluorescence‐lifetime measurements are used to understand the behavior of a range of Cy3‐based dyes attached to the 3′ end of G‐quadruplex DNA. The simulations revealed that the dyes interact extensively with the G‐quadruplex. Identification of preferred dye positions relative to the G‐quadruplex in the simulations allows the impact of dye–DNA interactions on FRET results to be determined. All the dyes show significant deviations from the common approximation of being freely rotating and not interacting with the host, but one of the Cy3 dye analogues is slightly closer to this case.
Predominant Information Quality Scheme for the Essential Amino Acids: An Information‐Theoretical Analysis
Authors: Esquivel Rodolfo O. , Molina‐Espíritu Moyocoyani , López‐Rosa Sheila , Soriano‐Correa Catalina , Barrientos‐Salcedo Carolina , Kohout Miroslav , Dehesa Jesús S. 
Published: July 2015

AbstractIn this work we undertake a pioneer information‐theoretical analysis of 18 selected amino acids extracted from a natural protein, bacteriorhodopsin (1C3W). The conformational structures of each amino acid are analyzed by use of various quantum chemistry methodologies at high levels of theory: HF, M062X and CISD(Full). The Shannon entropy, Fisher information and disequilibrium are determined to grasp the spatial spreading features of delocalizability, order and uniformity of the optimized structures. These three entropic measures uniquely characterize all amino acids through a predominant information‐theoretic quality scheme (PIQS), which gathers all chemical families by means of three major spreading features: delocalization, narrowness and uniformity. This scheme recognizes four major chemical families: aliphatic (delocalized), aromatic (delocalized), electro‐attractive (narrowed) and tiny (uniform). All chemical families recognized by the existing energy‐based classifications are embraced by this entropic scheme. Finally, novel chemical patterns are shown in the information planes associated with the PIQS entropic measures.
The effects of forest conversion to oil palm on ground‐foraging ant communities depend on beta diversity and sampling grain
Authors: Wang Wendy Y. , Foster William A. 
Published: July 2015

AbstractBeta diversity – the variation in species composition among spatially discrete communities – and sampling grain – the size of samples being compared – may alter our perspectives of diversity within and between landscapes before and after agricultural conversion. Such assumptions are usually based on point comparisons, which do not accurately capture actual differences in total diversity. Beta diversity is often not rigorously examined. We investigated the beta diversity of ground‐foraging ant communities in fragmented oil palm and forest landscapes in Sabah, Malaysia, using diversity metrics transformed from Hill number equivalents to remove dependences on alpha diversity. We compared the beta diversities of oil palm and forest, across three hierarchically nested sampling grains. We found that oil palm and forest communities had a greater percentage of total shared species when larger samples were compared. Across all grains and disregarding relative abundances, there was higher beta diversity of all species among forest communities. However, there were higher beta diversities of common and very abundant (dominant) species in oil palm as compared to forests. Differences in beta diversities between oil palm and forest were greatest at the largest sampling grain. Larger sampling grains in oil palm may generate bigger species pools, increasing the probability of shared species with forest samples. Greater beta diversity of all species in forest may be attributed to rare species. Oil palm communities may be more heterogeneous in common and dominant species because of variable community assembly events. Rare and also common species are better captured at larger grains, boosting differences in beta diversity between larger samples of forest and oil palm communities. Although agricultural landscapes support a lower total diversity than natural forests, diversity especially of abundant species is still important for maintaining ecosystem stability. Diversity in agricultural landscapes may be greater than expected when beta diversity is accounted for at large spatial scales.
Electrografting of 4‐tert‐Butylcatechol on GC Electrode. Selective Electrochemical Determination of Homocysteine
Authors: Salehzadeh Hamid , Nematollahi Davood , Alizadeh Saber 
Published: July 2015

AbstractA new sensor based on the grafting of 4‐tert‐butylcatechol on the surface of a glassy carbon electrode (GC) was developed for the catalytic oxidation of homocysteine (Hcy). The GC‐modified electrode exhibited a reversible redox response at neutral pH. Under the optimum conditions cyclic voltammetric results indicated the excellent electrocatalytic activity of modified electrode toward the oxidation of Hcy at reduced over‐potential about 350 mV. A linear dynamic range of 0.01–3.0 mM and a detection limit of 1.0 µM were obtained for Hcy. The modified electrode was used as an electrochemical sensor for selective determination of Hcy in human blood.
Ultrasensitive Electrochemical Immunosensor for Detection of Tumor Necrosis Factor‐α Based on Functionalized MWCNT‐Gold Nanoparticle/Ionic Liquid Nanocomposite
Authors: Mazloum‐Ardakani Mohammad , Hosseinzadeh Laleh , Khoshroo Alireza 
Published: July 2015

AbstractA novel and highly sensitive electrochemical immunosensor was developed for the detection of protein biomarker tumor necrosis factor‐alpha (TNF‐α) based on immobilization of TNF‐α‐antibody (anti‐TNF‐α) onto robust nanocomposite containing gold nanoparticles (AuNP), multiwalled carbon nanotubes (MWCNTs) and ionic liquid (1‐buthyl‐3‐methylimidazolium bis (trifluoromethyl sulfonyl)imide). Functionalized MWCNT‐gold nanoparticle was produced by one‐step synthesis based on the direct redox reaction. The electrochemical properties of nanocomposite were characterized by electrochemical impedance spectroscopy and cyclic voltammetry. The anti‐TNF‐α was immobilized or entrapped in the nanocomposite and used in a sandwich type complex immunoassay with anti‐TNF‐α labeled with horseradish peroxidase as secondary antibody. Under optimum conditions, the immunosensor could detect TNF‐α in a linear range from 6.0 to 100 pg mL−1 with a low detection limit of 2.0 pg mL−1. The simple fabrication method, high sensitivity, good reproducibility, stability, as well as acceptable accuracy for TNF‐α detection in human serum samples are the main advantages of this immunosensor, which might have broad applications in protein diagnostics and bioassay.
Reduced Graphene Oxide/Carbon Nanotube/Gold Nanoparticles Nanocomposite Functionalized Screen‐Printed Electrode for Sensitive Electrochemical Detection of Endocrine Disruptor Bisphenol A
Authors: Wang Yi‐Cheng , Cokeliler Dilek , Gunasekaran Sundaram 
Published: July 2015

AbstractWe fabricated a highly sensitive electrochemical sensor for the determination of bisphenol A (BPA) in aqueous solution by using reduced graphene oxide (RGO), carbon nanotubes (CNT), and gold nanoparticles (AuNPs)‐modified screen‐printed electrode (SPE). GO/CNT nanocomposite was directly reduced to RGO/CNT on SPE at room temperature. AuNPs were then electrochemically deposited in situ on RGO/CNT‐modified SPE. Under optimized conditions, differential pulse voltammetry (DPV) produced linear current responses for BPA concentrations of 1.45 to 20 and 20 to 1,490 nM, with a calculated detection limit of an ultralow 800 pM. The sensor response was unaffected by the presence of interferents such as phenol, p‐nitrophenol, pyrocatechol, 2,4‐dinitrophenol, and hydroquinone.
Novel Reagentless Label‐Free Detection Principle for Affinity Interactions Resulted in Conductivity Increase of Conducting Polymer
Authors: Komkova Maria A. , Andreyev Egor A. , Nikitina Vita N. , Krupenin Vladimir A. , Presnov Denis E. , Karyakina Elena E. , Yatsimirsky Anatoly K. , Karyakin Arkady A. 
Published: July 2015

AbstractWe report on the novel reagentless and label‐free detection principle allowing discrimination of specific binding over non‐specific interactions. Unlike majority of impedimetric and conductometric (bio)sensors, which specific and unspecific signals are directed in the same way (resistance increase), making doubtful their real applications, the response of the reported system results in resistance decrease, which is directed oppositely to the background. The mechanism of the resistance decrease is the polyaniline self‐doping, i.e. as an alternative to proton doping, an appearance of the negatively charged aromatic ring substituents in polymer chain. Negative charge at boronic ring substituent appears as a result of complex formation with di‐ and triols, i.e. specific binding. Thermodynamic data on interaction of the electropolymerized aminophenylboronic acids with saccharides and hydroxy acids indicate that the observed resistance decrease is due to polymer interaction with polyols. A possibility to detect microorganisms (Penicillum chrysogenum) on the basis of interdigitated electrodes modified with boronate substituted polyaniline is also shown. The first reported conductivity increase as a specific signal opens new horizons for reagentless affinity sensors.
Metal Nanoparticle‐Loaded Mesoporous Carbon Nanoparticles: Electrical Contacting of Redox Proteins and Electrochemical Sensing Applications
Authors: Trifonov Alexander , Tel‐Vered Ran , Fadeev Michael , Cecconello Alessandro , Willner Itamar 
Published: July 2015

AbstractA new method to incorporate metal nanoparticles, NPs, into pores of mesoporous carbon nanoparticles, MPC NPs, is presented. MPC NPs loaded with metal ion solutions are capped with protein units. The electrochemical reduction of the pore‐entrapped ions, followed by digestion of the protein caps, yields metal NPs‐loaded MPC NPs electrodes. Pt NPs/MPC NPs electrodes are used for the electrocatalyzed reduction of O2 or H2O2. Furthermore, the metal NPs electrically contact enzymes with the bulk electrodes, as demonstrated for glucose oxidase‐capped Pt NPs/MPC NPs electrodes that electrocatalyze glucose oxidation, and for horseradish peroxidase‐capped Au NPs/MPC NPs electrodes, which electrocatalyze H2O2 reduction.
A Zinc Oxide Carbon Nanotube Based Sensor for In Situ Monitoring of Hydrogen Peroxide in Swimming Pools
Authors: Wayu Mulugeta B. , King Julie E. , Johnson Jacqueline A. , Chusuei Charles C. 
Published: July 2015

AbstractZinc oxide nanoparticles were tethered to carbon nanotubes to form an electrochemical sensing composite, which was characterized using transmission electron microscopy, and X‐ray photoelectron and attenuated total reflectance infrared spectroscopies. The sensor′s electrocatalytic response for measuring hydrogen peroxide was investigated using cyclic voltammetry and chronoamperometry in a dynamic, well defined swimming pool environment. A wide, linear response in the concentration range of 0.025–7.0 mM at a potential of −0.360 V was shown, with rapid response time (<5 s). The sensor had excellent reproducibility, exhibited stability and selectivity, and was able to measure concentrations in a dynamic environment as they varied.
Exploring Redox Behavior of Neutral pH Active Poly(melamine) and its Electrocatalytic Origination towards NADH Detection
Authors: Baskar Selvaraj , Thiyagarajan Natarajan , Chang Jen‐Lin , Zen Jyh‐Myng 
Published: July 2015

AbstractWe report here in detail the redox properties and catalytic origination of poly(melamine). Gradual change in redox behavior of the monomer from polymer is explained by grafting monomer and different amounts of polymer on screen printed carbon electrode. The redox peak of the poly(melamine) is pH‐dependent with a slope of −60 mV/pH, representing a Nernstian type proton‐coupled electron‐transfer process. Catalytic origination from the NH‐NH bond formed in polymer is proved using NADH as a probe. This polymer is effective to catalyze NADH oxidation with a wide linear range of 1 μM–10 mM and a detection limit (S/N=3) of 0.67 μM. Most importantly, unlike most neutral pH active polymer dyes, it shows high stability even after 15 days.
Electrochemistry Investigation on the Graphene/Electrolyte Interface
Authors: Du Xiaowei , Guo Hui , Jin Yan , Jin Qinghui , Zhao Jianlong 
Published: July 2015

AbstractIn this study, the graphene/electrolyte interface was investigated in detail by the electrochemical method. The total interface capacitance was calculated from the electrochemical impedance spectroscopy (EIS) results, and its responses to different concentrations and pHs were also investigated. The minimum point of the capacitance was found to shift to right (vs. Ag/AgCl) as the concentration increased, and to left with increasing pH. As a comparison, gold/electrolyte interface was investigated in the same way, but didn’t show the similar behavior. To further explore the interface capacitance, proper models were proposed to fit the EIS results. Two constant‐phase elements (CPE) were used in the graphene‐electrolyte interface model to represent the double‐layer capacitance (CPEdl) and the quantum capacitance (CPEq), respectively. The CPEq exhibited its sensitivity to concentration and pH, while CPEdl did not. This study gives a new aspect to detect concentration and pH, and may provide a reference for the graphene‐based supercapacitor research.