bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solvent Effect and Reactivity Trend in the Aerobic Oxidation of 1,3‐Propanediols over Gold Supported on Titania: NMR Diffusion and Relaxation Studies
Authors: D'Agostino Carmine , Kotionova Tatyana , Mitchell Jonathan , Miedziak Peter J. , Knight David W. , Taylor Stuart H. , Hutchings Graham J. , Gladden Lynn F. , Mantle Mick D. 
Published: July 2013

AbstractIn recent work, it was reported that changes in solvent composition, precisely the addition of water, significantly inhibits the catalytic activity of Au/TiO2 catalyst in the aerobic oxidation of 1,4‐butanediol in methanol due to changes in diffusion and adsorption properties of the reactant. In order to understand whether the inhibition mechanism of water on diol oxidation in methanol is generally valid, the solvent effect on the aerobic catalytic oxidation of 1,3‐propanediol and its two methyl‐substituted homologues, 2‐methyl‐1,3‐propanediol and 2,2‐dimethyl‐1,3‐propanediol, over a Au/TiO2 catalyst has been studied here using conventional catalytic reaction monitoring in combination with pulsed‐field gradient nuclear magnetic resonance (PFG‐NMR) diffusion and NMR relaxation time measurements. Diol conversion is significantly lower when water is present in the initial diol/methanol mixture. A reactivity trend within the group of diols was also observed. Combined NMR diffusion and relaxation time measurements suggest that molecular diffusion and, in particular, the relative strength of diol adsorption, are important factors in determining the conversion. These results highlight NMR diffusion and relaxation techniques as novel, non‐invasive characterisation tools for catalytic materials, which complement conventional reaction data.
Reactivity of Dialumane and “Dialumene” Compounds toward Alkenes
Authors: Zhao Yanxia , Lei Yibo , Dong Qingsong , Wu Biao , Yang Xiao‐Juan 
Published: July 2013

AbstractThe reactions of dialumane [L(thf)AlAl(thf)L] (1, L=[{(2,6‐iPr2C6H3)NC(Me)}2]2−) with stilbene and styrene afforded the oxidation/insertion products [L(thf)Al(CH(Ph)CH(Ph))AlL] (2) and [L(thf)Al(CH(Ph)CH2)Al(thf)L] (3), respectively. In the presence of Na metal, precursor 1 reacted with butadienes, possibly through the reduced “dialumene” or the “carbene‐like” :AlL species, to yield aluminacyclopentenes [LAl(CH2C(Me)C(Me)CH2)Na]n (4 a) and [Na(dme)3][LAl(CH2C(Me)CHCH2)] (4 b, dme=dimethoxyethane) as [1+4] cycloaddition products, as well as the [2+4] cycloaddition product 1,6‐dialumina‐3,8‐cyclodecadiene, [{Na(dme)}2][LAl(CH2C(Me)C(Me)CH2)2AlL] (5). The possible mechanisms of the cycloaddition reactions were studied by using DFT computations.
Aryl‐Phosphonate Lanthanide Complexes and Their Fluorinated Derivatives: Investigation of Their Unusual Relaxometric Behavior and Potential Application as Dual Frequency 1H/19F MRI Probes
Authors: Placidi Matteo P. , Botta Mauro , Kálmán Ferenc K. , Hagberg Gisela E. , Baranyai Zsolt , Krenzer Andreas , Rogerson Alexandria K. , Tóth Imre , Logothetis Nikos K. , Angelovski Goran 
Published: July 2013

AbstractA series of low molecular weight lanthanide complexes were developed that have high 1H longitudinal relaxivities (r1) and the potential to be used as dual frequency 1H and 19F MR probes. Their behavior was investigated in more detail through relaxometry, pH‐potentiometry, luminescence, and multinuclear NMR spectroscopy. Fitting of the 1H NMRD and 17O NMR profiles demonstrated a very short water residence lifetime (<10 ns) and an appreciable second sphere effect. At lower field strengths (20 MHz), two of the complexes displayed a peak in r1 (21.7 and 16.3 mM−1 s−1) caused by an agglomeration, that can be disrupted through the addition of phosphate anions. NMR spectroscopy revealed that at least two species are present in solution interconverting through an intramolecular binding process. Two complexes provided a suitable signal in 19F NMR spectroscopy and through the selection of optimized imaging parameters, phantom images were obtained in a MRI scanner at concentrations as low as 1 mM. The developed probes could be visualized through both 1H and 19F MRI, showing their capability to function as dual frequency MRI contrast agents.
Spontaneous Translocation of Antitumor Oxaliplatin, its Enantiomeric Analogue, and Cisplatin from One Strand to Another in Double‐Helical DNA
Authors: Malina Jaroslav , Natile Giovanni , Brabec Viktor 
Published: July 2013

AbstractOxaliplatin and cisplatin belong to the class of platinum‐based anticancer agents. Formation of DNA adducts by these complexes and the consequences for its structure and function, is the mechanistic paradigm by which these drugs exert their antitumor activity. We show that employing short oligonucleotide duplexes containing single, site‐specific 1,3‐intrastrand cross‐links of oxaliplatin, its enantiomeric analogue, or cisplatin and by using gel electrophoresis that under physiological conditions the coordination bonds between platinum and the N7 position of guanine residues involved in the cross‐links of the PtII complexes can be cleaved. This cleavage may lead to linkage isomerization reactions between these metallodrugs and double‐helical DNA. For instance, approximately 25 % 1,3‐intrastrand cross‐links of the platinum complexes isomerized after 192 h (at 310 K in 200 mM NaClO4). Differential scanning calorimetry of duplexes containing single, site‐specific cross‐links of oxaliplatin, its enantiomeric analogue, and cisplatin reveals that one of the driving forces that leads to the lability of DNA cross‐links of these metallodrugs is a difference between the thermodynamic destabilization induced by the cross‐link and by the adduct into which it could isomerize. The rearrangements may proceed in the way that cross‐links originally formed in one strand of the DNA can spontaneously translocate from one DNA strand to its complementary counterpart, which may evoke walking of the platinum complex on DNA molecule. In addition, the differences in the kinetics of the rearrangement reactions and the thermodynamic destabilization of DNA observed for adducts of oxaliplatin and its enantiomeric analogue confirm that the chirality at the carrier 1,2‐diaminocyclohexane ligand can considerably affect structural and other physical properties of DNA adducts and consequently their biological effects. In aggregate, interesting generalization of the results described in this work might be that the migration of oxaliplatin, its enantiomeric analogue, or cisplatin from one strand to another in double‐helical DNA controlled by energetic signatures of these agents might contribute to a better understanding of their cytotoxic and mutagenic potential.
Staphylococcus aureus Penicillin‐Binding Protein 2 Can Use Depsi‐Lipid II Derived from Vancomycin‐Resistant Strains for Cell Wall Synthesis
Authors: Nakamura Jun , Yamashiro Hidenori , Miya Hiroto , Nishiguchi Kenzo , Maki Hideki , Arimoto Hirokazu 
Published: July 2013

AbstractVancomycin‐resistant Staphylococcus aureus (S. aureus) (VRSA) uses depsipeptide‐containing modified cell‐wall precursors for the biosynthesis of peptidoglycan. Transglycosylase is responsible for the polymerization of the peptidoglycan, and the penicillin‐binding protein 2 (PBP2) plays a major role in the polymerization among several transglycosylases of wild‐type S. aureus. However, it is unclear whether VRSA processes the depsipeptide‐containing peptidoglycan precursor by using PBP2. Here, we describe the total synthesis of depsi‐lipid I, a cell‐wall precursor of VRSA. By using this chemistry, we prepared a depsi‐lipid II analogue as substrate for a cell‐free transglycosylation system. The reconstituted system revealed that the PBP2 of S. aureus is able to process a depsi‐lipid II intermediate as efficiently as its normal substrate. Moreover, the system was successfully used to demonstrate the difference in the mode of action of the two antibiotics moenomycin and vancomycin.
Cascade‐ and Orthoamide‐Type Overman Rearrangements of Allylic Vicinal Diols
Authors: Nakayama Yasuaki , Sekiya Ruriko , Oishi Hiroki , Hama Naoto , Yamazaki Miki , Sato Takaaki , Chida Noritaka 
Published: July 2013

AbstractThis article describes the details of two new types of Overman rearrangement from allylic vicinal diols. Starting from identical diols, both bis(imidate)s and cyclic orthoamides were selectively synthesized by simply changing the reaction conditions. Whilst exposure of the bis(imidate)s to thermal conditions initiated the double Overman rearrangement to introduce two identical nitrogen groups in a single operation (the cascade‐type Overman rearrangement), the reaction of cyclic orthoamides resulted in a single rearrangement (the orthoamide‐type Overman rearrangement). The newly generated allylic alcohols from the orthoamide‐type reaction can potentially undergo a variety of further transformations. For instance, we demonstrated an Overman/Claisen sequence in one pot. The most conspicuous feature of this method is that it offers precise control over the number of Overman rearrangements from the same allylic vicinal diols. This method also excludes the tedious protecting‐group manipulations of the homoallylic alcohols, which are necessary in conventional Overman rearrangements. All of the performed rearrangements proceeded in a completely diastereoselective fashion through a chair‐like transition state.
Size‐Dependent Enhancement of Electrocatalytic Oxygen‐Reduction and Hydrogen‐Evolution Performance of MoS2 Particles
Authors: Wang Tanyuan , Gao Dongliang , Zhuo Junqiao , Zhu Zhiwei , Papakonstantinou Pagona , Li Yan , Li Meixian 
Published: July 2013

AbstractMoS2 particles with different size distributions were prepared by simple ultrasonication of bulk MoS2 followed by gradient centrifugation. Relative to the inert microscale MoS2, nanoscale MoS2 showed significantly improved catalytic activity toward the oxygen‐reduction reaction (ORR) and hydrogen‐evolution reaction (HER). The decrease in particle size was accompanied by an increase in catalytic activity. Particles with a size of around 2 nm exhibited the best dual ORR and HER performance with a four‐electron ORR process and an HER onset potential of −0.16 V versus the standard hydrogen electrode (SHE). This is the first investigation on the size‐dependent effect of the ORR activity of MoS2, and a four‐electron transfer route was found. The exposed abundant Mo edges of the MoS2 nanoparticles were proven to be responsible for the high ORR catalytic activity, whereas the origin of the improved HER activity of the nanoparticles was attributed to the plentiful exposed S edges. This newly discovered process provides a simple protocol to produce inexpensive highly active MoS2 catalysts that could easily be scaled up. Hence, it opens up possibilities for wide applications of MoS2 nanoparticles in the fields of energy conversion and storage.
Re‐examination of the C6Li6 Structure: To Be, or not To Be Symmetric
Authors: Moreno Diego , Martínez‐Guajardo Gerardo , Díaz‐Celaya Andrés , Mercero José M. , de Coss Romeo , Perez‐Peralta Nancy , Merino Gabriel 
Published: July 2013

AbstractThe potential energy surface of C6Li6 was re‐examined and a new non‐symmetric global minimum was found. The new structure can be described as three C22− fragments strongly aggregated through lithium bridges. At high temperatures, fluxionality is perceived instead of dissociation. At 600 and 900 K, the BOMD simulations show that the lithium mobility is high, indicating that the cluster behaves in a liquid‐like manner (BOMD=Born–Oppenheimer molecular dynamics).
Propagation of Biochirality: Crossovers and Nonclassical Crystallization Kinetics of Aspartic Acid in Water
Authors: Lee Tu , Lin Yu Kun , Tsai Ya Chung , Lee Hung Lin 
Published: July 2013

ABSTRACTAll experimental procedures discussed could be treated as a screening tool for probing the existence of molecular association among the chiral molecules and the solvent system. The molecular association phases of a racemic conglomerate solution (CS) and a racemic compound solution (RCS), and the templating effect of aspartic acid solid surface were observed to minimize the chance of redissolving racemic conglomerate and racemic compound aspartic acid in water and reforming an RCS in crossovers experiments. Only 1 %wt% of l‐aspartic acid was adequate enough to induce a transformation from a racemic compound aspartic acid to a racemic conglomerate aspartic acid. This would make the propagation of biochirality more feasible and sound. However, tetrapeptide, (l‐aspartic acid)4, failed to induce enantioseparation as templates purely by crystallization. Nonclassical crystallization theory was needed to take into account the existence of a CS. Fundamental parameters of the crystallization kinetics such as the induction time, interfacial energy, Gibbs energetic barrier, nucleation rate, and critical size of stable nuclei of: (i) racemic compound aspartic acid, (ii) racemic compound aspartic acid seeded with 1 %wt% l‐aspartic acid, (iii) racemic conglomerate aspartic acid, and (iv) l‐aspartic acid were evaluated and compared with different initial supersaturation ratios. Morphological studies of crystals grown from the crystallization kinetics were also carried out.Chirality 25:768–779, 2013. © 2013 Wiley Periodicals, Inc.
Elutriation in inverse fluidisation using non‐Newtonian pseudoplastic liquids
Authors: Das Bimal , Ganguly Uma Prasad , Das Sudip Kumar 
Published: July 2013

AbstractExperiments have been carried out to determine the minimum elutriation velocity for inverse fluidisation system using single and binary systems of four different solids of polymeric materials of different sizes and shapes, and four different non‐Newtonian pseudoplastic liquids in two different Perspex columns. The effects of different operating parameters on elutriation velocity have been investigated. Empirical correlations have been developed to predict the minimum elutriation velocity as a function of physical and dynamic variables of the system. Statistical analysis of the correlation suggests that is of acceptable accuracy.
Phase Evolution of CuS System in Ethylene Glycol Solution: the Effect of Anion and PVP on the Transformation of Thiourea
Authors: Fang Zhen , Wang Chenyan , Fan Fan , Hao Shenghua , Long Liuyang , Song Yixuan , Qiang Tingting 
Published: July 2013

AbstractThe transformation mechanisms of thiourea in ethylene glycol solution was systematically investigated in this report, which shows the transformation process is influenced by the anion (NO3−, Cl−, Br−) and polyvinylpyrrolidone (PVP). Thiourea (tu) isomerizes into ammonium thiocyanate when NO3− is present, regardless of the existence of PVP. For Cl−, thiourea coordinates with copper anion to form [Cu(tu)]Cl·1/2H2O complex whether PVP is present. When it comes to Br−, thiourea hydrolyzes in the cooperation of PVP or coordinates with copper anion to form [Cu(tu)Br]·1/2H2O complex without PVP. The different transformation routes will lead to different phase evolution of the CuS system. This work may provide a new understanding of the transformation of thiourea in ethylene glycol solution. The optical properties of the as‐prepared copper sulfides exhibit signi?cant stoichiometry‐dependent features which may have potential applications in semiconductor photovoltaic devices.
Fluorocarbon and Hydrocarbon Benzodioxocycloalkane (C8–C10) End Groups: Effects on Mesomorphism
Authors: Cao Wanwan , Liu Peilian , Chen Hongren , Zhu Yaohang , Chen Rihao , Zhou Qifang , Zeng Zhuo 
Published: July 2013

AbstractA new class of benzodioxocycloalkane‐based (C8–C10) liquid crystals were prepared. The impact of ring (C8–C10) as end group was investigated. The 8–9 membered ring derivatives, 3a–3b, exhibited the nematic phases (N). The mesomorphic behaviors were weakened with increasing the size of the ring. For the ?uorinated medium ring (C8–C10) 3d–3f, it was found only the fluorinated ten membered ring 3f showed the LC phases behaviours. Modification of the ring size with different length alkyl groups and variation of the alkyl to polyfluoroalkyl markedly influenced the properties of these compounds.
Radical Addition of Perfluoroalkyl Iodides to Alkenes and Alkynes Initiated by Sodium Dithionite in an Aqueous Solution in the Presence of a Novel Fluorosurfactant
Authors: Xiao Zhiwei , Hu Huawei , Ma Jiaoli , Chen Qingyun , Guo Yong 
Published: July 2013

AbstractA new fluorinated anionic surfactant Cl(CF2)6O(CF2)2SO3N(C2H5)4 was prepared and characterized. The application of the fluorosurfactant allowed the fluoroalkylation to occur in the water without adding organic solvent. The addition of perfluoroalkyl iodides with olefins and alkynes under the initiation of Na2S2O4 in water in the presence of the fluorosurfactant gave the corresponding adducts in good to excellent yields. The fluorosurfactant was suitable for a radical addition process.
Triazole and Benzotriazole Derivatives as Novel Inhibitors for p90 Ribosomal S6 Protein Kinase 2: Synthesis, Molecular Docking and SAR Analysis
Authors: Yuan Jun , Zhong Ye , Li Shiliang , Zhao Xue , Luan Guoqin , Zhao Zhenjiang , Huang Jin , Li Honglin , Xu Yufang 
Published: July 2013

AbstractA series of triazole and benzotriazole derivatives as novel p90 ribosomal S6 protein kinase 2 (RSK2) inhibitors were designed and synthesized. The in vitro activities against RSK2 were evaluated, and among 14 compounds, compounds 5, 6, 11, 12, 13 and 14 exhibited enzyme IC50 values of 8.91, 2.86, 3.19, 3.05, 4.49 and 2.09 µmol/L respectively. The proposed binding modes were simulated using molecular docking method, and the docking results coupled with the structure‐activity relationship (SAR) analysis indicated that all these active compounds bound to the RSK2 ATP binding site at NTKD, and the electron‐donating groups on the 4‐position of phenyl were the determinant point for the inhibitory activity.
A new replicate variance estimator for unequal probability sampling without replacement
Authors: Escobar Emilio L. , Berger Yves G. 
Published: July 2013

AbstractWe propose a new replicate variance estimator suitable for differentiable functions of estimated totals. The proposed variance estimator is defined for any unequal‐probability without‐replacement sampling design, it naturally includes finite population corrections and it allows two‐stage sampling. We show its design‐consistency and its close relationship with linearization variance estimators. When estimating a total, the proposed estimator reduces to the Horvitz–Thompson variance estimator. Simulations suggest that the proposed variance estimator is more stable than its replicate competitors.The Canadian Journal of Statistics41: 508–524; 2013 © 2013 Statistical Society of Canada
Baseflow and Runoff Event Metal Concentrations, Partition and Its Relation with Physicochemical Variables in an Agroforestry Catchment
Authors: Palleiro Laura , Rodríguez‐Blanco María Luz , Taboada‐Castro María Mercedes , Taboada‐Castro María Teresa 
Published: July 2013

AbstractPartitioning to suspended sediments plays an important role in controlling metal speciation in natural waters. In order to model both dissolved and particulate forms of metals, it is essential to determine possible relationships between partition coefficient (KD) and various water quality variables. This paper examines temporal variability in particulate and dissolved metals (Al, Fe, Mn, Cu, and Zn) collected from a rural stream (NW Spain) during three years under baseflow and runoff events conditions, and investigates the role of pH, suspended sediments (SS) and dissolved organic carbon (DOC) on KD of these metals. The mean concentrations of metals during events were much higher than those in baseflow (except MnD and CuD), but particulate metals were always predominant. Metal concentrations did not exhibit a seasonal pattern. Generally, a similar pattern of metals to discharge was seen for both hydrological conditions, although different metal‐discharge relationships were observed depending on the type and form of the metal: negative for FeD and MnD, no relation for AlD, CuD, and ZnD, and positive correlation for all particulate metals (except for CuP and ZnP in baseflow). Partitioning results showed that SS and DOC were the main factors in controlling KD of all metals during events (except for Fe) as well as KD of Al under baseflow. SS play the most important role on KD of Cu and Zn in baseflow, and DOC on KD of Fe (regardless of the discharge regime). For all the above‐mentioned findings, this study demonstrates the need to consider hydrological changes when we analyze geochemical factors affecting metal concentrations, even in relatively unpolluted environments.
Synthesis and in vitro Evaluation of West Nile Virus Protease Inhibitors Based on the 1,3,4,5‐Tetrasubstituted 1H‐Pyrrol‐2(5H)‐one Scaffold
Authors: Gao Yaojun , Samanta Sanjay , Cui Taian , Lam Yulin 
Published: July 2013

AbstractWest Nile virus (WNV), a member of the Flaviviridae family, is a mosquito‐borne pathogen that causes a large number of human infections each year. There are currently no vaccines or antiviral therapies available for human use against WNV. Therefore, efforts to develop new chemotherapeutics against this virus are highly desired. In this study, a WNV NS2B–NS3 protease inhibitor with a 1,3,4,5‐tetrasubstituted 1H‐pyrrol‐2(5H)‐one scaffold was identified by screening a small library of nonpeptidic compounds. Optimization of this initial hit by the synthesis and screening of a focused library of compounds with this scaffold led to the identification of a novel uncompetitive inhibitor ((−)‐1a16, IC50=2.2±0.7 μM) of the WNV NS2B–NS3 protease. Molecular docking of the chiral compound onto the WNV protease indicates that the R enantiomer of 1a16 interferes with the productive interactions between the NS2B cofactor and the NS3 protease domain and is thus the preferred isomer for inhibition of the WNV NS2B–NS3 protease.
Thalamic Input to Representations of the Teeth, Tongue, and Face in Somatosensory Area 3b of Macaque Monkeys
Authors: Cerkevich Christina M. , Qi Hui‐Xin , Kaas Jon H. 
Published: July 2013

ABSTRACTRepresentations of the parts of the oral cavity and face in somatosensory area 3b of macaque monkeys were identified with microelectrode recordings and injected with different neuroanatomical tracers to reveal patterns of thalamic projections to tongue, teeth, and other representations in primary somatosensory cortex. The locations of injection sites and resulting labeled neurons were further determined by relating sections processed to reveal tracers to those processed for myeloarchitecture in the cortex and multiple architectural stains in the thalamus. The ventroposterior medial subnucleus (VPM) for touch was identified as separate from the ventroposterior medial parvicellular nucleus (VPMpc) for taste by differential expression of several types of proteins. Our results revealed somatotopically matched projections from VPM to the part of 3b representing intra‐oral structures and the face. Retrogradely labeled cells resulting from injections in area 3b were also found in other thalamic nuclei including: anterior pulvinar (Pa), ventroposterior inferior (VPI), ventroposterior superior (VPS), ventroposterior lateral (VPL), ventral lateral (VL), center median (CM), central lateral (CL), and medial dorsal (MD). None of our injections, including those into the representation of the tongue, labeled neurons in VPMpc, the thalamic taste nucleus. Thus, area 3b does not appear to be involved in processing taste information from the thalamus. This result stands in contrast to those reported for New World monkeys. J. Comp. Neurol. 521:3954–3971, 2013. © 2013 Wiley Periodicals, Inc.