bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular Engineering of Boryl Oxasmaragdyrins through Peripheral Modification: Structure–Efficiency Relationship
Authors: Mane Sandeep B. , Hung Chen‐Hsiung 
Published: February 2015

AbstractExpanded porphyrins with the absorption profile down to the infrared region through increased π‐conjugation are suitable candidates for a low energy sensitizer. Oxasmaragdyrin boron complexes, a class of aromatic‐core‐modified expanded porphyrin with 22 π‐electrons, have been recently utilized as an efficient low energy sensitizer in dye‐sensitized solar cells. In this paper, we have prepared a series of eight novel boryl oxasmaragdyrins through molecular engineering on the periphery and their overall photovoltaic performances in dye‐sensitized solar cells are evaluated. With the help of photophysical, electrochemical, and photovoltaic studies, it is revealed that molecular structure, especially the number and position of the donor–acceptor groups play a pivotal role in their photovoltaic performance. Presence of the two well‐separated split Soret bands in the 400–500 nm region of UV/Vis spectrum ensures broader coverage of absorption wavelengths. Even though the two‐anchoring‐group dyes (SM5–SM8) bind strongly to TiO2 compared to one‐anchoring‐group dyes (SM1–SM4), the latter have superior photovoltaic performance than the former. Dye SM1, with two hexyloxyphenyl donors and one carboxylic acid anchor showed the best overall conversion efficiency of 4.36 % (JSC=10.91 mA cm−2; VOC=0.59 V; FF=0.68). This effective modulation of photovoltaic performance through structural engineering of the dyes will serve as a guideline for the future design of efficient low energy light‐harvesting sensitizers.
CaO as Drop‐In Colloidal Catalysts for the Synthesis of Higher Polyglycerols
Authors: Kirby Fiona , Nieuwelink Anne‐Eva , Kuipers Bonny W. M. , Kaiser Anton , Bruijnincx Pieter C. A. , Weckhuysen Bert M. 
Published: February 2015

AbstractGlycerol is an attractive renewable building block for the synthesis of polyglycerols, which find application in the cosmetic and pharmaceutical industries. The selective etherification of glycerol to higher oligomers was studied in the presence of CaO colloids and the data are compared with those obtained from NaOH and CaO. The materials were prepared by dispersing CaO, CaCO3, or Ca(OH)2 onto a carbon nanofiber (CNF) support. Colloidal nanoparticles were subsequently dispensed from the CNF into the reaction mixture to give CaO colloids that have a higher activity than equimolar amounts of bulk CaO and NaOH. Optimization of the reaction conditions allowed us to obtain a product with Gardner color number <2, containing no acrolein and minimal cyclic byproducts. The differences in the CaO colloids originating from CNF and bulk CaO were probed using light scattering and conductivity measurements. The results confirmed that the higher activity of the colloids originating from CaO/CNF was due to their more rapid formation and smaller size compared with colloids from bulk CaO. We thus have developed a practical method for the synthesis of polyglycerols containing low amounts of Ca.
Direct Spectroscopic Evidence of the Mechanism behind the Phase Transition of [2,2]‐Paracyclophane
Authors: Wolf Hilke , Lock Nina , Parker Stewart F. , Stalke Dietmar 
Published: February 2015

Abstract[2,2]‐Paracyclophane undergoes phase transitions at 45 and 60 K. Based on simultaneous Raman spectroscopy and inelastic neutron scattering experiments (12–70 K), it was shown that a twisting motion of the ethylene bridge perpendicular to the plane of the aromatic rings drives the phase transition. The low‐temperature (<45 K) and high‐temperature (>60 K) conformers only differ by this twisting motion, which freezes out below 45 K and is thermally averaged above 60 K. Between 45 and 60 K, the system gains energy until the phase transition is complete.
Reactivity and Operational Stability of N‐Tailed TAMLs through Kinetic Studies of the Catalyzed Oxidation of Orange II by H2O2: Synthesis and X‐ray Structure of an N‐Phenyl TAML
Authors: Warner Genoa R. , Mills Matthew R. , Enslin Clarissa , Pattanayak Shantanu , Panda Chakadola , Panda Tamas Kumar , Gupta Sayam Sen , Ryabov Alexander D. , Collins Terrence J. 
Published: February 2015

AbstractThe catalytic activity of the N‐tailed (“biuret”) TAML (tetraamido macrocyclic ligand) activators [Fe{4‐XC6H3‐1,2‐(NCOCMe2NCO)2NR}Cl]2− (3; N atoms in boldface are coordinated to the central iron atom; the same nomenclature is used in for compounds 1 and 2 below), [X, R=H, Me (a); NO2, Me (b); H, Ph (c)] in the oxidative bleaching of Orange II dye by H2O2 in aqueous solution is mechanistically compared with the previously investigated activator [Fe{4‐XC6H3‐1,2‐(NCOCMe2NCO)2CMe2}OH2]− (1) and the more aggressive analogue [Fe(Me2C{CON(1,2‐C6H3‐4‐X)NCO}2)OH2]− (2). Catalysis by 3 of the reaction between H2O2 and Orange II (S) occurs according to the rate law found generally for TAML activators (v=kIkII[FeIII][S][H2O2]/(kI[H2O2]+kII[S]) and the rate constants kI and kII at pH 7 both decrease within the series 3 b>3 a>3 c. The pH dependency of kI and kII was investigated for 3 a. As with all TAML activators studied to‐date, bell‐shaped profiles were found for both rate constants. For kI, the maximal activity was found at pH 10.7 marking it as having similar reactivity to 1 a. For kII, the broad bell pH profile exhibits a maximum at pH about 10.5. The condition kI≪kII holds across the entire pH range studied. Activator 3 b exhibits pronounced activity in neutral to slightly basic aqueous solutions making it worthy of consideration on a technical performance basis for water treatment. The rate constants ki for suicidal inactivation of the active forms of complexes 3 a–c were calculated using the general formula ln([S0]/[S∞])=(kII/ki)[FeIII]; here [FeIII], [S0], and [S∞] are the total catalyst concentration and substrate concentration at time zero and infinity, respectively. The synthesis and X‐ray characterization of 3 c are also described.
Oxygen‐Atom Transfer Chemistry and Thermolytic Properties of a Di‐tert‐Butylphosphate‐Ligated Mn4O4 Cubane
Authors: Van Allsburg Kurt M. , Anzenberg Eitan , Drisdell Walter S. , Yano Junko , Tilley T. Don 
Published: February 2015

Abstract[Mn4O4{O2P(OtBu)2}6] (1), an Mn4O4 cubane complex combining the structural inspiration of the photosystem II oxygen‐evolving complex with thermolytic precursor ligands, was synthesized and fully characterized. Core oxygen atoms within complex 1 are transferred upon reaction with an oxygen‐atom acceptor (PEt3), to give the butterfly complex [Mn4O2{O2P(OtBu)2}6(OPEt3)2]. The cubane structure is restored by reaction of the latter complex with the O‐atom donor PhIO. Complex 1 was investigated as a precursor to inorganic Mn metaphosphate/pyrophosphate materials, which were studied by X‐ray absorption spectroscopy to determine the fate of the Mn4O4 unit. Under the conditions employed, thermolyses of 1 result in reduction of the manganese to MnII species. Finally, the related butterfly complex [Mn4O2{O2P(pin)}6(bpy)2] (pin=pinacolate) is described.
Pd0‐Catalyzed Intramolecular α‐Arylation of Sulfones: Domino Reactions in the Synthesis of Functionalized Tetrahydroisoquinolines
Authors: Solé Daniel , Pérez‐Janer Ferran , Mancuso Raffaella 
Published: February 2015

AbstractA new strategy for the synthesis of tetrahydroisoquinolines based on the Pd0‐catalyzed intramolecular α‐arylation of sulfones is reported. The combination of this Pd‐catalyzed reaction with intermolecular Michael and aza‐Michael reactions allows the development of two‐ and three‐step domino processes to synthesize diversely functionalized scaffolds from readily available starting materials.
A Surprising Substituent Effect Provides a Superior Boronic Acid Catalyst for Mild and Metal‐Free Direct Friedel–Crafts Alkylations and Prenylations of Neutral Arenes
Authors: Ricardo Carolynne L. , Mo Xiaobin , McCubbin J. Adam , Hall Dennis G. 
Published: February 2015

AbstractThe development of more general and efficient catalytic processes for Friedel–Crafts alkylations is an important objective of interest toward the production of pharmaceuticals and commodity chemicals. Herein, 2,3,4,5‐tetrafluorophenylboronic acid was identified as a potent air‐ and moisture‐tolerant metal‐free catalyst that significantly improves the scope of direct Friedel–Crafts alkylations of a variety of slightly activated and neutral arenes, including polyarenes, with allylic and benzylic alcohols. This method also provides a simple alternative for the direct installation of prenyl units commonly found in naturally occurring arenes. Alkylations with benzylic alcohols occur under exceptionally mild conditions.
Simultaneous Induction of Axial and Planar Chirality in Arene–Chromium Complexes by Molybdenum‐Catalyzed Enantioselective Ring‐Closing Metathesis
Authors: Kamikawa Ken , Arae Sachie , Wu Wei‐Yi , Nakamura Chihiro , Takahashi Tamotsu , Ogasawara Masamichi 
Published: February 2015

AbstractThe molybdenum‐catalyzed asymmetric ring‐closing metathesis of the various Cs‐symmetric (π‐arene)chromium substrates provides the corresponding bridged planar‐chiral (π‐arene)chromium complexes in excellent yields with up to >99 % ee. With a bulky and unsymmetrical substituent, such as N‐indolyl or 1‐naphthyl, at the 2‐positions of the η6‐1,3‐diisopropenylbenzene ligands, both biaryl‐based axial chirality and π‐arene‐based planar chirality are simultaneously induced in the products. The axial chirality is retained even after the removal of the dicarbonylchromium fragment, and the chiral biaryl/heterobiaryl compounds are obtained with complete retention of the enantiopurity.
Eine Geschichte von Pech und Schwefel
Authors: Hübner Karl 
Published: February 2015

AbstractAutoreifen, Taucheranzüge, Einmalhandschuhe, Dichtungen und vieles, vieles mehr. Ein Leben ohne Gummi ist heute schwer vorstellbar. Doch es war ein schwieriger Weg, ehe man solche Elastomere herstellen konnte. Denn der Ausgangsstoff, Naturkautschuk, ist heikel – und die aus ihm hergestellten Produkte alles andere als form‐ und temperaturstabil. Es war Charles Goodyear, dem es 1839 gelang, die langen Polymerketten im Naturkautschuk miteinander zu vernetzen.
Chemie, die uns guttut
Authors: Harrer Roswitha 
Published: February 2015

AbstractNeben Nähen und Klammern kann verletztes Gewebe auch geklebt werden. Nach wie vor werden aber Klebstoffe gesucht, die ungiftig und nicht auswaschbar sind und auch dynamisches Gewebe wie den Herzmuskel nach Verletzung schnell und zuverlässig verschließen können.
Macrolidantibiotika gegen Methicillin‐resistente Staphylokokken
Authors: Hille‐Rehfeld Annette 
Published: February 2015

AbstractSekundärmetabolite von Bakterien, z. B. Polyketide, sind potentielle Leitstrukturen für die Entwicklung neuer Wirkstoffe. Die Modulbauweise der Synthesemaschinerie dieser Substanzen bzw. die Anordnung der zugrundeliegenden Gene in Syntheseclustern ermöglicht die gezielte Suche nach potentiellen Wirkstoffproduzenten durch Genome Mining (Prospektion des Genoms).
Analysis of 4‐Component Borehole Strain Observation Based on Strain Invariant
Authors: Xu‐Yan LIU , Zi‐Yan WANG , Ying‐Feng JI 
Published: February 2015

AbstractWe offered 5 groups of formulae to compute strain invariant of 4‐component borehole strain stations in China and the United States with Mohr's circle model in this paper. 5 groups of the principal strain and its directions of 25 stations are computed and analyzed with the methods of correlation and regression. The result shows that strain invariant changes smoothly in 1–2 years after installation; the principal strain and the principal direction are becoming more and more equal to each other; the correlation coefficient and regression coefficient between 5 groups of maximum and minimum principal strain is close to 1. These showed that borehole strain gauge data objectively record the nominal strain. However, 5 groups of principal directions are very different, the reason for this phenomenon is that the maximum root mean square errors of principal strain obtained by error propagation law are limited, but maximum root mean square errors of principal strain directions are unlimited. Finally, some factors that affect the borehole strain invariant consistency are given. The result shows that the borehole strain observation technology has made important progress after half a century of practice, but there are still some technical problems to be solved because of its special difficulties.
A Differential Effective Medium Model of Multiple‐Porosity Rock and Its Analytical Approximations for Dry Rock
Authors: Hong‐Bing LI , Jia‐Jia ZHANG 
Published: February 2015

AbstractThe classic differential effective medium (DEM) theory can be used to determine the elastic properties of the porous medium, but the final elastic properties of multiple‐porosity rock depend on the order of adding the different pore‐type inclusions due to the lack of DEM equations for multiple‐porosity rock. This paper first derives the differential equations of both Zimmermann's and Norris's versions for multiple‐porosity rock from the Kuster‐Toksöz theory. The elastic moduli predicted by the DEM equations of Norris's version never violate Hashin‐Shtrikman bounds while those predicted by the DEM equations of Zimmermann's version violate bounds in some cases. Then, we derive analytical solutions of the bulk and shear moduli for dry rock from the differential equations of Norris's version by applying an analytical approximation for dry‐rock modulus ratio, in order to decouple these equations. The validity of these analytical approximations is tested by integrating the full DEM equation numerically. The analytical formulae give good estimates of the numerical results over the whole porosity range. The analytical formulae have been used to predict the elastic moduli for the sandstone experimental data by assuming that the porous rock contains dual‐porosity of both cracks and pores. The results show that they can accurately predict the variations of elastic moduli with porosity for dry sandstones. We also apply nonlinear global optimization algorithm to find the best estimate for the pore volume percentage of both cracks and pores by minimizing the error between theoretical predictions and experimental measurements based on the dual‐porosity DEM analytical model. The inversion results of the sandstone experimental data show that there is no direct correlation between the crack volume percentage and clay volume.
Preparation of the Free‐Air Gravity Anomaly Map in the Land and Seas of China and Adjacent Areas Using Multi‐Source Gravity Data and Interpretation of the Gravity Field
Authors: Jin‐Yu YANG , Xun‐Hua ZHANG , Fei‐Fei ZHANG , Bo HAN , Zhen‐Xing TIAN 
Published: February 2015

AbstractMulti‐source gravity data including measurements on land, shipboard surveys, satellite altimetry, Bouguer gravity anomalies and EGM2008 global gravity model data were collected and analyzed for compiling the free‐air gravity anomaly map on a scale of 1:5000000 in the land and seas of China and adjacent areas. The data merging and integration method was established based on analysis of the accuracy and resolution of different sources of gravity data. Evenly distributed land gravity data was gridded in flat land areas. A synthetic method using Bouguer gravity and high precision topographic data to calculate the free‐air gravity data was proposed to fill the land areas where the gravity measurement is hardly or impossible to implement due to complex terrain. Data comparison between the synthetic free‐air gravity data, measured data and EGM2008 data proves that using the synthetic data is a better choice for filling the areas lacking real data. This method was also applied to the continental and island areas outside mainland China where there are no real data collected. The STD analysis method was applied to the northern part of the South China Sea to compare the accuracy of three independent gravity data, the shipboard gravity data and two kinds of satellite altimetry derived gravity data, the SS series from Scripps, US and DNSC08GRA from DTU, Denmark. SSV18.1 and DNSC08GRA data, which show very good consistence in terms of accuracy and resolution. The standard deviation of the latest two satellite gravity data in the SCS is less than 2 mGal, which is a major improvement compared with the previous SS16.1. With the rectification of shipboard gravity data, the wide coverage of satellite gravity data could be used for small‐scale free‐air gravity mapping. In the coastal zone, the EGM2008 global potential model was used as a reference field providing a seamless gravity transition from land to ocean. Wavelet transform and multiscale analyses were applied to decompose the free‐air gravity field in China and its adjacent areas to help gravity field interpretation. Eight anomaly areas were demarcated by three horizontal and four vertical first‐order gravity gradient belts. Anomaly subareas and the second‐order gravity gradient belts were delineated in the gravity field to provide evidence for establishing the tectonic framework in the block tectonic scheme.
Variable selection for inhomogeneous spatial point process models
Authors: Yue Yu (Ryan) , Loh Ji Meng 
Published: February 2015

AbstractIn this work, we consider variable selection when modelling the intensity and clustering of inhomogeneous spatial point processes, integrating well‐known procedures in the respective fields of variable selection and spatial point process modelling to introduce a simple procedure for variable selection in spatial point process modelling. Specifically, we consider modelling spatial point data with Poisson, pairwise interaction and Neyman–Scott cluster models, and incorporate LASSO, adaptive LASSO, and elastic net regularization methods into the generalized linear model framework for fitting these point models. We perform simulation studies to explore the effectiveness of using each of the three‐regularization methods in our procedure. We then use the procedure in two applications, modelling the intensity and clustering of rainforest trees with soil and geographical covariates using a Neyman–Scott model, and of fast food restaurant locations in New York City with Census variables and school locations using a pairwise interaction model.The Canadian Journal of Statistics43: 288–305; 2015 © 2015 Statistical Society of Canada
Premature Ventricular Contraction–Induced Cardiomyopathy
Authors: Saurav Alok , Smer Aiman , Abuzaid Ahmed , Bansal Ojas , Abuissa Hussam 
Published: February 2015

AbstractPremature ventricular contractions are of common occurrence in routine clinical practice. Though generally perceived as of benign consequence in healthy people in the absence of heart disease, their presence can be a harbinger of fatal ventricular tachyarrhythmia in individuals with structural heart disease. With some of the latest insights into the treatment of ventricular tachyarrhythmia, especially with the advent of catheter ablation, there has been renewed interest in premature ventricular contractions, not only as a predictor of arrhythmia, but also for their potential etiological association with cardiomyopathy.
Sentinel lymph node biopsy is indicated for patients with thick clinically lymph node‐negative melanoma
Authors: Yamamoto Maki , Fisher Kate J. , Wong Joyce Y. , Koscso Jonathan M. , Konstantinovic Monique A. , Govsyeyev Nicholas , Messina Jane L. , Sarnaik Amod A. , Cruse C. Wayne , Gonzalez Ricardo J. , Sondak Vernon K. , Zager Jonathan S. 
Published: February 2015

BACKGROUNDSentinel lymph node biopsy (SLNB) is indicated for the staging of clinically lymph node‐negative melanoma of intermediate thickness, but its use is controversial in patients with thick melanoma.METHODSFrom 2002 to 2012, patients with melanoma measuring ≥4 mm in thickness were evaluated at a single institution. Associations between survival and clinicopathologic characteristics were explored.RESULTSOf 571 patients with melanomas measuring ≥4 mm in thickness and no distant metastases, the median age was 66 years and 401 patients (70.2%) were male. The median Breslow thickness was 6.2 mm; the predominant subtype was nodular (45.4%). SLNB was performed in 412 patients (72%) whereas 46 patients (8.1%) presented with clinically lymph node‐positive disease and 113 patients (20%) did not undergo SLNB. A positive SLN was found in 161 of 412 patients (39.1%). For SLNB performed at the study institution, 14 patients with a negative SLNB developed disease recurrence in the mapped lymph node basin (false‐negative rate, 12.3%). The median disease‐specific survival (DSS), overall survival (OS), and recurrence‐free survival (RFS) for the entire cohort were 62.1 months, 42.5 months, and 21.2 months, respectively. The DSS and OS for patients with a negative SLNB were 82.4 months and 53.4 months, respectively; 41.2 months and 34.7 months, respectively, for patients with positive SLNB; and 26.8 months and 22 months, respectively, for patients with clinically lymph node‐positive disease (P<.0001). The median RFS was 32.4 months for patients who were SLNB negative, 14.3 months for patients who were SLNB positive, and 6.8 months for patients with clinically lymph node‐positive disease (P<.0001).CONCLUSIONSWith an acceptably low false‐negative rate, patients with thick melanoma and a negative SLNB appear to have significantly prolonged RFS, DSS, and OS compared with those with a positive SLNB. Therefore, SLNB should be considered as indicated for patients with thick, clinically lymph node‐negative melanoma. Cancer 2015;121:1628–1636. © 2015 American Cancer Society.
Predicting early mortality in resectable pancreatic adenocarcinoma: A cohort study
Authors: Sohal Davendra P.S. , Shrotriya Shiva , Glass Kate Tullio , Pelley Robert J. , McNamara Michael J. , Estfan Bassam , Shapiro Marc , Wey Jane , Chalikonda Sricharan , Morris‐Stiff Gareth , Walsh R. Matthew , Khorana Alok A. 
Published: February 2015

BACKGROUNDSurvival after surgical resection for pancreatic cancer remains poor. A subgroup of patients die early (<6 months), and understanding factors associated with early mortality may help to identify high‐risk patients. The Khorana score has been shown to be associated with early mortality for patients with solid tumors. In the current study, the authors evaluated the role of this score and other prognostic variables in this setting.METHODSThe current study was a cohort study of patients who underwent surgical resection for pancreatic cancer from January 2006 through June 2013. Baseline (diagnosis ±30 days) parameters were used to define patients as high risk (Khorana score ≥3). Statistically significant univariable associations and a priori prognostic variables were tested in multivariable models; adjusted hazard ratios (HR) were calculated.RESULTSThe study population comprised 334 patients. The median age was 67 years, 50% of the study population was female, and 86% of the patients were white. The pancreatic head was the primary tumor site for 73% of patients; 67% of tumors were T3 and 63% were N1. The median Khorana score was 2; 152 patients (47%) were determined to be high risk. Adjunctive treatment included chemotherapy (70%) and radiotherapy (40%). The postoperative (30‐day) mortality rate was 0.9%. The 6‐month mortality rate for the entire cohort was 9.4%, with significantly higher rates observed for high‐risk patients (13.4% vs 5.6%; P = .02). On multivariable analyses (examining a total of 326 patients), the Khorana score (HR for high risk, 2.31; P = .039) and elevated blood urea nitrogen (HR, 4.34; P<.001) were associated with early mortality.CONCLUSIONSPatients at high risk of early mortality after surgical resection of pancreatic adenocarcinoma can be identified using simple baseline clinical and laboratory parameters. Future studies should address preoperative interventions in these patients at high risk of early mortality. Cancer 2015;121:1779–1784. © 2015 American Cancer Society.