bluuebunny/crossref_metadata_2025 huggingface dataset:
Different β nucleants and the resultant microstructural, fracture, and tensile properties for filled and unfilled ISO polypropylene
Authors: Varley Russell J. , Dell'Olio Mel , Yuan Qiang , Khor Sarah , Leong K. H. , Bateman Stuart
Published: July 2012

This article explores the use of two β nucleants to improve the fracture behavior of filled and unfilled homo‐polypropylene (PP). The first was based upon an organic quinacridone, whereas the second was based upon the inorganic calcium pimelate. Formulations containing various concentrations of nucleant were prepared using single screw extrusion and then characterized by X‐ray diffraction, differential scanning calorimetry (DSC), Izod impact strength, and tensile testing. The quinacridone nucleating agent produced higher levels of β crystallinity and better improvement in strain to failure, whereas the calcium pimelate imparted greater improvement in impact strength regardless of whether the PP was filled or unfilled. No direct relationship between β crystallinity and fracture properties was observed though synergistic enhancement in impact strength was evident. By varying the concentration of calcium carbonate in the calcium pimelate from 10 : 1, 5 : 1, 2 : 1, and 1 : 1 weight composition of calcium carbonate to pimelic acid, similar property enhancements were achieved regardless of composition although the 10 : 1 sample did produce superior elongation to break. The importance of cooling rate on microstructure within each sample was explored via a through the thickness study using DSC and nano‐indenting methods. Variations in the β content through the thickness were related to cooling and found to be independent of sample composition and processing. Elastic properties varied inversely with β content. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Dendronized polyamides supports for Mo catalysts
Authors: Qin Mulan , Liu Meihua , Zhang Qing , Li Cheng , Liang Shuquan
Published: July 2012

Dendronized polyamides of generations 1 and 2 were grafted with ethylenediamine (en) ligands at their peripheries by the condensation of chloromethyl groups and en molecules. The obtained dendronized complexes were further equipped with MoO2acac2 to form the catalysts PGn‐en‐Mo. The results of FT‐IR and thiocyanate photometric analysis confirmed the successful immobilization of Mo catalysts on dendronized polyamides. The catalytic properties of PGn‐en‐Mo were first studied in the epoxidation of cyclohexene with tert‐butyl hydroperoxide and exhibited high catalytic activity and selectivity. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Vulcanization of ethylene‐propylene–terpolymer‐based rubber mixtures by radiation processing
Authors: Stelescu Maria Daniela , Manaila Elena , Craciun Gabriela
Published: July 2012

Elastomers are materials used in a large range of industrial and household applications. A common physical‐chemical treatment is curing (crosslinking), imparting the rubber mechanical and thermal stability. Elastomers show low thermal conductivity values, and therefore, require complex and high‐cost heating methods; thus, the ionizing (accelerated electrons) method shows high interest for the grafting and crosslinking processes. In addition to the lack of environmental impact, reliability, flexibility, and low costs render the radiation technologies especially attractive. The article presents the results concerning trimethylolpropane‐trimethacrylate coagent concentration effect, on the mechanical properties of the ethylene‐propylene–terpolymer (EPDM) rubber vulcanized by electron beam (EB). Mechanical properties of EB irradiated samples were compared with the dibenzoyl peroxide cured samples. Dependence of mechanical properties on irradiation dose was determined from a dose range of 0 kGy to 200 kGy. Dibenzoyl peroxide vulcanization at 160°C was carried out on the EPDM samples as well. Two types of blends have been analyzed: fillers and nonfillers. The results showed an increase in mechanical properties as a function of increasing polyfunctional monomer level. Also, based on the comparison between EB and dibenzoyl peroxide vulcanization efficiency, the results show that EB irradiation gave the best results. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Molecular modeling of physical aging in epoxy polymers
Authors: Bandyopadhyay Ananyo , Odegard Gregory M.
Published: July 2012

Epoxy resins are often exposed to prolonged periods of sub‐Tg temperatures which cause physical aging to occur. Because physical aging can compromise the performance of epoxies and their composites and because experimental techniques cannot provide all of the necessary physical insight that is needed to fully understand physical aging, efficient computational approaches to predict the effects of physical aging on thermomechanical properties are needed. In the current study, a new method is developed to efficiently establish molecular models of epoxy resins that represent the corresponding molecular structure at specific aging times. Although this approach does not simulate the physical aging process directly, it is useful in establishing molecular models that resemble physically aged states of epoxies. Such models are useful for predicting the thermomechanical properties of aged epoxy resins to facilitate the design of durable engineering structures. For demonstration purposes, the developed method is applied to an EPON 862/diethylene toluene diamine epoxy system for three different crosslink densities. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Macromolecular sorbent materials for urea capture
Authors: Wilson Lee D. , Xue Chen
Published: July 2012

Three types of chitosan–glutaraldehyde (Chi–Glu) crosslinked copolymer materials were prepared at various Chi–Glu weight ratios (i.e., 1 : 0.0835, 1 : 0.334, and 1 : 0.585) and variable reaction times. The corresponding Chi–Glu copolymer materials were imbibed in CuSO4 solution to yield impregnated materials in the form of copolymer/Cu(II) complexes. The copolymer materials were characterized using FTIR spectroscopy and thermogravimetry analysis. Urea sorption isotherms were obtained in aqueous solution at 295 K and pH 7 with pristine chitosan, Chi–Glu copolymers (i.e., 1 : 0.0835 and 1 : 0.585), and the corresponding Chi–Glu/Cu(II) complexes. The concentration of unbound urea was monitored indirectly using a colorimetric method with p‐dimethylaminobenzaldehyde. The equilibrium adsorption data were analyzed using the Sips isotherm model. The uptake of urea with pristine chitosan was 4.7% w/w, whereas Chi–Glu copolymers display increased sorption (Qm = 10.6–17.1% w/w) with increasing glutaraldehyde content. Urea sorption is further enhanced (Qm = 16.3–26.4% w/w) for copolymer Chi–Glu/Cu(II) complexes. The preparation of Chi–Glu copolymers at various conditions illustrates that the sorption capacity and molecular recognition of urea can be systematically tuned via crosslinking and the formation of copolymer/Cu(II) complexes, and these results are related to a previously reported study (Shimizu and Fujishige, J. Biomed. Mater. Res. 1983, 17, 597). © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Option pricing when asset returns jump interruptedly
Authors: Miao Daniel Wei‐Chung , Yu Steve Hsin‐Ting
Published: July 2012

This paper proposes an extension of Merton's jump‐diffusion model to reflect the time inhomogeneity caused by changes of market states. The benefit is that it simultaneously captures two salient features in asset returns: heavy tailness and volatility clustering. On the basis of an empirical analysis where jumps are found to happen much more frequently in risky periods than in normal periods, we assume that the Poisson process for driving jumps is governed by a two‐state on‐off Markov chain. This makes jumps happen interruptedly and helps to generate different dynamics under these two states. We provide a full analysis for the proposed model and derive the recursive formulas for the conditional state probabilities of the underlying Markov chain. These analytical results lead to an algorithm that can be implemented to determine the prices of European options under normal and risky states. Numerical examples are given to demonstrate how time inhomogeneity influences return distributions, option prices, and volatility smiles. The contrasting patterns seen in different states indicate the insufficiency of using time‐homogeneous models and justify the use of the proposed model. Copyright © 2012 John Wiley & Sons, Ltd.
Diffusion Tensor Imaging in Autism Spectrum Disorder: A Review
Authors: Travers Brittany G. , Adluru Nagesh , Ennis Chad , Tromp Do P. M. , Destiche Dan , Doran Sam , Bigler Erin D. , Lange Nicholas , Lainhart Janet E. , Alexander Andrew L.
Published: July 2012

White matter tracts of the brain allow neurons and neuronal networks to communicate and function with high efficiency. The aim of this review is to briefly introduce diffusion tensor imaging methods that examine white matter tracts and then to give an overview of the studies that have investigated white matter integrity in the brains of individuals with autism spectrum disorder (ASD). From the 48 studies we reviewed, persons with ASD tended to have decreased fractional anisotropy and increased mean diffusivity in white matter tracts spanning many regions of the brain but most consistently in regions such as the corpus callosum, cingulum, and aspects of the temporal lobe. This decrease in fractional anisotropy was often accompanied by increased radial diffusivity. Additionally, the review suggests possible atypical lateralization in some white matter tracts of the brain and a possible atypical developmental trajectory of white matter microstructure in persons with ASD. Clinical implications and future research directions are discussed. Autism Res 2012, 5: 289–313. © 2012 International Society for Autism Research, Wiley Periodicals, Inc.
Pharmacokinetics of salsalate and salicylic acid in normal and diabetic rats
Authors: Cao Yanguang , DuBois Debra C. , Almon Richard R. , Jusko William J.
Published: July 2012

The pharmacokinetics (PK) of salsalate (SS) and salicylic acid (SA) was assessed in normal Wistar and diabetic Goto‐Kakizaki rats. Three PK studies were conducted: (1) PK of SA in normal rats after intravenous dosing of SA at 20, 40, 80 mg/kg. (2) PK of SS and SA in normal rats after oral dosing of SS at 28, 56, 112 mg/kg. (3) PK during 4 months feeding of SS‐containing diet in both normal and diabetic rats. The disposition of SS and SA were evaluated simultaneously using a pharmacokinetic model comprising several transit absorption steps and linear and nonlinear dual elimination pathways for SA. The results indicated that the nonlinear elimination pathway of SA only accounted for a small fraction of the total clearance (< 12%) at therapeutic concentrations. A flat profile of SA was observed after oral dosing of SS, particularly at a high dose. The possible reasons for this flat profile were posed. During the SS‐diet feeding, the diabetic rats achieved lower blood concentrations of SA than normal rats with a higher apparent clearance (CL/F), possibly due to incomplete (47%) bioavailability. Such CL/F decreased with age in both diabetic and normal rats. The effect of diabetes on SA pharmacokinetics may necessitate increased dosing in the future usage of SS in diabetes. Copyright © 2012 John Wiley & Sons, Ltd.
Responses of the embryonic epigenome to maternal diabetes
Authors: Salbaum J. Michael , Kappen Claudia
Published: July 2012

Maternal diabetes and obesity are independent risk factors for neural tube defects, although it is unclear whether the effects are mediated by common pathogenic mechanisms. In this manuscript, we report a genome‐wide survey of histone acetylation in neurulation stage embryos from mouse pregnancies with different metabolic conditions: maternal diabetes, and maternal consumption of a high fat content diet. We find that maternal diabetes, and independently, exposure to high‐fat diet, are associated with increases and decreases of H3 and H4 histone acetylation in the embryo. Intriguingly, changes of H3K27 acetylation marks are significantly enriched near genes known to cause neural tube defects in mouse mutants. These data suggest that epigenetic changes in response to diet and metabolic condition may contribute to increased risk for neural tube defects in diabetic and obese pregnancies. Importantly, the responses to high‐fat diet and maternal diabetes were distinct, suggesting that perturbed embryonic development under these conditions is mediated by different molecular pathways. This conclusion is supported by morphometric analyses that reveal a trend for maternal diabetes to delay embryonic development in the C57BL/6 strain, while high‐fat diet appears to be associated with accelerated development. Taken together, our results link changes in histone acetylation to metabolic conditions during pregnancy, and implicate distinct epigenetic mechanisms in susceptibility to neural tube defects under conditions of maternal diabetes and obesity. Birth Defects Research (Part A) 2012. © 2012 Wiley Periodicals, Inc.
Isolation and Neuroprotective Activities of Acylated Iridoids from Valeriana jatamansi
Authors: Xu Jing , Guo Yuanqiang , Xie Chunfeng , Jin Da‐Qing , Gao Jie , Gui Liping
Published: July 2012

Three new iridoids, jatairidoids A–C (1–3, resp.), have been isolated from the roots of Valeriana jatamansi (V. wallichii). Their structures were elucidated by spectroscopic methods (IR, ESI‐MS, HR‐ESI‐MS, 1D‐ and 2D‐NMR). Compounds 1 and 2 are C(3)‐epimers. The three compounds were evaluated for their neuroprotective effects against MPP+‐induced neuronal cell death in human dopaminergic neuroblastoma SH‐SY5Y cells. All the isolates exhibited moderate neuroprotective effects.
Jiangxienone, a New Compound with Potent Cytotoxicity against Tumor Cells from Traditional Chinese Medicinal Mushroom Cordyceps jiangxiensis
Authors: Xiao Jian‐Hui , Sun Zhong‐Hua , Pan Wei‐Dong , Lü Yu‐Hong , Chen Dai‐Xiong , Zhong Jian‐Jiang
Published: July 2012

A new compound, named jiangxienone, has been isolated from a culture of the traditional Chinese medicinal mushroom Cordyceps jiangxiensis, and its chemical structure was established on the basis of spectroscopic and chemical techniques. Jiangxienone showed potent cytotoxic effects against human gastric adenocarcinoma SGC‐7901 cell and human lung carcinoma A549 cell with IC50 values ranging from 1.38 to 2.93 μM, i.e., with at least approximately six‐fold stronger cytotoxicity than cisplatin, a first‐line chemotherapy drug for cancer patients.
Volatile Secondary Metabolites of Micromeria dalmaticaBenth. (Lamiaceae): Biosynthetical and Chemotaxonomical Aspects
Authors: Radulović Niko S. , Blagojević Polina D.
Published: July 2012

Analysis by GC and GC/MS of the essential oil obtained from above‐ground parts of Micromeria dalmatica Benth. allowed the identification of 116 components, comprising 93.6% of the total oil composition. The major compounds are 3‐oxygenated p‐menthane monoterpenes and were identified as pulegone (29.6%), menthone (11.7%), and piperitenone (10.8%). The chemical composition of this and additional 30 oils obtained from selected Micromeria Benth. taxa were compared by using multivariate statistical analysis (agglomerative hierarchical cluster analysis and principal component analysis (PCA)). The results of statistical analyses, as well as the domination of different concurrent p‐menthane‐skeleton‐type monoterpene biosynthetical sub‐branches in the compared M. dalmatica samples, implied the occurrence of at least two different chemotypes of the mentioned species.
Carbohydrate Chelation in Neutral Aqueous Solution: The threo‐Tetritolato‐Pd4 Butterfly Motif
Authors: Allscher Thorsten , Klüfers Peter
Published: July 2012

Alditols (“sugar alcohols”, “glycitols”) form palladium(II) complexes in neutral aqueous solution if they can provide the threitol partial structure. This requirement excludes erythritol, ribitol, and allitol when applied to the common tetritols, pentitols, and hexitols. The remaining alditols are able to arrange their threo‐tetraol‐O4 pattern to an almost planar rhomb, to which four PdIIN2 (N2=bidentate nitrogen ligand) centres bind in a butterfly‐shaped Pd4 motif. Bridging is the exclusive bonding mode of the four alkoxido donors. In contrast to the butterfly complexes, all alditols are able to form a species at a pH intermediate between neutrality and the stronger alkaline conditions of non‐bridging diolato‐palladium(II) binding, namely, the μ‐triolato bonding mode. A Pd2(μ‐triolato) unit shows the middle O atom of a propanetriolato fragment as a bridging ligator, with the lateral O atoms binding in the terminal mode.
Organocatalytic Kinetic Resolution Cascade Reactions: New Mechanistic and Stereochemical Manifold in Diphenyl Prolinol Silyl Ether Catalysis
Authors: McGarraugh Patrick G. , Johnston Ryne C. , Martínez‐Muñoz Aurora , Cheong Paul Ha‐Yeon , Brenner‐Moyer Stacey E.
Published: July 2012

A new cascade reaction involving an iminium‐catalyzed intramolecular oxa‐Michael addition followed by an enamine‐catalyzed intermolecular Michael addition is reported herein. This cascade reaction generates enantiopure, highly functionalized tetrahydropyrans and tetrahydrofurans in a one‐pot reaction and in up to 89 % combined yield and up to 99 % ee. This cascade reaction is catalyzed by diaryl prolinol silyl ethers, which are a privileged class of catalysts. The stereochemical outcome of these cascade reactions is unprecedented. Computational studies indicate that this stereochemical outcome arises from nonclassical hydrogen‐bonding interactions between the electrophile and the substrate, and from entropic considerations of preorganization. The unprecedented configurations of the cascade products, combined with the computational models, reveal for the first time that asymmetric induction by diaryl prolinol silyl ether catalysts is not always exclusively reagent controlled. The stereochemical outcome also arises from a kinetic resolution or dynamic kinetic resolution of the β‐stereocenter through an enamine‐catalyzed intermolecular reaction. This unprecedented organocascade reaction mechanism may be adaptable to diaryl prolinol silyl ether‐catalyzed cascade reactions, in which both the iminium‐ and enamine‐catalyzed steps are intermolecular, an underdeveloped type of cascade reaction.
The Role of the Alcohol and Carboxylic Acid in Directed Ruthenium‐Catalyzed C(sp3)H α‐Alkylation of Cyclic Amines
Authors: Bergman Sheba D. , Storr Thomas E. , Prokopcová Hana , Aelvoet Karel , Diels Gaston , Meerpoel Lieven , Maes Bert U. W.
Published: July 2012

A general directed Ru‐catalyzed C(sp3)H α‐alkylation protocol for piperidines (less‐reactive substrates than the corresponding five‐membered cyclic amines) has been developed. The use of a hindered alcohol (2,4‐dimethyl‐3‐pentanol) as the solvent and catalyst activator, and a catalytic amount of trans‐1,2‐cyclohexanedicarboxylic acid is necessary to achieve a high conversion to product. This protocol was used to effectively synthesize a number of 2‐hexyl‐ and 2,6‐dihexyl piperidines, as well as the alkaloid (±)‐solenopsin A. Kinetic studies have revealed that the carboxylic acid additive has a significant effect on catalyst initiation, catalyst longevity, and reverses the reaction selectivity compared with the acid‐free reaction (promotes alkylation versus competing alkene reduction).
Highly Strained Heterometallacycles of Group 4 Metallocenes with Bis(diphenylphosphino)amide Ligands
Authors: Haehnel Martin , Hansen Sven , Spannenberg Anke , Arndt Perdita , Beweries Torsten , Rosenthal Uwe
Published: July 2012

A study regarding coordination chemistry of the bis(diphenylphosphino)amide ligand Ph2P‐N‐PPh2 at Group 4 metallocenes is presented herein. Coordination of N,N‐bis(diphenylphosphino)amine (1) to [(Cp2TiCl)2] (Cp=η5‐cyclopentadienyl) generated [Cp2Ti(Cl)P(Ph2)N(H)PPh2] (2). The heterometallacyclic complex [Cp2Ti(κ2‐P,P‐Ph2P‐N‐PPh2)] (3 Ti) can be prepared by reaction of 2 with n‐butyllithium as well as from the reaction of the known titanocene–alkyne complex [Cp2Ti(η2‐Me3SiC2SiMe3)] with the amine 1. Reactions of the lithium amide [(thf)3Li{N(PPh2)2}] with [Cp2MCl2] (M=Zr, Hf) yielded the corresponding zirconocene and hafnocene complexes [Cp2M(Cl){κ2‐N,P‐N(PPh2)2}] (4 Zr and 4 Hf). Reduction of 4 Zr with magnesium gave the highly strained heterometallacycle [Cp2Zr(κ2‐P,P‐Ph2P‐N‐PPh2)] (3 Zr). Complexes 2, 3 Ti, 4 Hf, and 3 Zr were characterized by X‐ray crystallography. The structures and bondings of all complexes were investigated by DFT calculations.
Combined Light‐ and Radio Wave Emission during Cracking of Particles
Authors: Aman Sergej , Tomas Jürgen
Published: July 2012

Der Zusammenhang zwischen den Licht‐ und Radioimpulsen, die während der Beanspruchung von Glaspartikeln entstehen, wurde untersucht. Dazu wurden die einzelnen Partikel und Partikelschichten zwischen zwei metallischen Platten, die unter angelegter Hochspannung stehen, mechanisch beansprucht. Die Lichtemission beginnt während der Entstehung der ersten Risse in den Glaspartikeln. Danach, mit einer Verzögerung von wenigen Mikrosekunden, wird die Radiowellenemission aus der neu entstandenen Schicht des zerkleinerten Glases registriert. Die Verzögerung zwischen dem Beginn der Lichtemission und die Entstehung der Radioimpulse stellt eine charakteristische Zerkleinerungszeit dar.
Construction of a Miniplant for the Catalytic Aerobic Cleavage of Methyl 9,10‐Dihydroxystearate
Authors: Behr Arno , Tenhumberg Nils
Published: July 2012

Die Entwicklung neuer Katalysatoren zur Oxidation chemischer Verbindungen unter Verwendung von Sauerstoff als kostengünstiges und umweltfreundliches Oxidationsmittel ist eine wichtige Aufgabe der aktuellen Forschung. Aufgrund der Gefahr der Bildung explosionsfähiger Gasgemische müssen bei diesen Oxidationen wirksame Maßnahmen zum Explosionsschutz getroffen werden. Es wird ein Sicherheitskonzept für den Explosionsschutz aerober Oxidationsreaktionen und der Aufbau einer Versuchsanlage vorgestellt. Als Modellreaktion wurde die oxidative Spaltung des 9,10‐Dihydroxystearinsäuremethylesters zum Azelainsäuremethylester und zur Nonansäure untersucht.
A Novel Method for One‐pot Synthesis of Furo[3,2‐c]coumarin Derivatives from 4‐Hydroxycoumarin and Arylglyoxal under Microwave Irradiation
Authors: Chen Zhiwei , Bi Jianhao , Su Weike
Published: July 2012

A novel one‐pot synthesis of furo[3,2‐c]coumarins has been developed from readily available starting materials 4‐hydroxycoumarin and arylglyoxal. This method is simple, rapid and good yielding.
Synthesis and Properties of Novel Aromatic Azo Compounds from Hydroxyazobenzene and Cyanuric Chloride
Authors: Li Weiwei , Xu Dongmei , Zhang Zhilan , Xu Ying
Published: July 2012

A new series of aromatic azo compounds with one, two, three and five azobenzene units were facilely constructed by dehydrochlorination reaction between p‐hydroxyazobenzene, 4,4′‐dihydroxyazobenzene and cyanuric chloride under very mild conditions. Their solubility, crystallinity, thermostability, UV‐vis absorption properties and photoisomerization behaviors were carefully examined. When the number of azobenzene unit grew, the solubility of the synthesized compounds basically decreased, the crystallinity of the synthesized compounds firstly rose then dropped, while the thermostability and UV‐vis absorption ability of the synthesized compounds greatly improved. All the aromatic azo compounds exhibited typical reversible photoisomerization behaviors and were expected to be applied in photosensitive material areas.
Aqueous‐mediated Michael Addition of Active Methylene Compounds with Nitroalkenes
Authors: Dong Wenkai , Xu Dongcheng , Xie Jianwu
Published: July 2012

A simple, atom economical and highly efficient green protocol has been developed for the synthesis of Michael adducts of nitroalkenes and 2‐amino‐2‐chromene derivatives by Michael addition of active methylene compounds (such as malononitrile and ethyl cyanoacetate) to nitroalkenes under aqueous‐mediated conditions. This green approach provided the desired products in high yields and the reaction scope proved to be quite broad.
Efficient Synthesis of 3‐Methyl‐Flavanones and Evaluation of Their Anti‐Bacterial Activity
Authors: Nawghare Beena , Funde Sharad , Raheem Abdul , Lokhande Pradeep
Published: July 2012

A series of 2‐phenyl‐2,3‐dihydrochromon‐4‐one derivatives (flavanone derivatives) were synthesized by silica gel assisted isomerization of several α‐methyl‐2′‐hydroxy chalcones in 74%–88% yield. These flavanones were further oxidized to 3‐methyl flavones by using iodine in dimethyl sulphoxide at 60°C in presence of acid. The newly synthesized derivatives were evaluated for in vitro study against Staphylococcus aureus, Micrococcus luteus and Staphylococcus epidermis.
A Highly Copper‐Selective Ratiometric Fluorescent Sensor Based on BODIPY
Authors: Huang Jinlong , Wang Bo , Ye Jianguo , Liu Bin , Qiu Huayu , Yin Shouchun
Published: July 2012

A new ratiometric fluorescent sensor (1) for Cu2+ based on 4,4‐difluoro‐4‐bora‐3a,4a‐diaza‐s‐indacene (BODIPY) with di(2‐picolyl)amine (DPA) as ion recognition subunit has been synthesized and investigated in this work. The binding abilities of 1 towards different metal ions such as alkali and alkaline earth metal ions (Na+, K+, Mg2+, Ca2+) and other metal ions ( Ba2+, Zn2+, Cd2+, Fe2+, Fe3+, Pb2+, Ni2+, Co2+, Hg2+, Ag+) have been examined by UV‐vis and fluorescence spectroscopies. 1 displays high selectivity for Cu2+ among all test metal ions and a ∼10‐fold fluorescence enhancement in I582/I558 upon excitation at visible excitation wavelength. The binding mode of 1 and Cu2+ is a 1:1 stoichiometry determined via studies of Job plot, the nonlinear fitting of the fluorometric titration and ESI mass.
Mechanism of Imidazole‐Promoted Ligation of Peptide Phenyl Esters
Authors: Wang Chen , Liu Lei
Published: July 2012

Imidazole‐promoted ligation of peptide phenyl esters was recently found to be a complementary method for protein chemical synthesis. Theoretical calculations have been carried out to understand the detailed mechanism of this particular ligation process. It is found that both the reaction of the phenyl ester with imidazole and the reaction of the acyl imidazole intermediate with cysteine proceed through an addition‐elimination mechanism. The cleavage of the CO bond in the reaction between the phenyl ester and imidazole is the rate‐limiting step of the overall ligation process. Interestingly, although the imidazole‐promoted phenyl ester ligation has a higher free energy barrier than the conventional thiophenol‐promoted native chemical ligation for a sterically less hindered C‐terminal amino acid (e.g. gylcine), for a sterically hindered C‐terminal amino acid (e.g. proline) the imidazole‐promoted phenyl ester ligation is calculated to be more favorable than the conventional thiophenol‐promoted native chemical ligation.
A Facile Method to Form a Densely Grafted PEO‐b‐P4VP Brush on Gold Surface
Authors: Yang Qian , Zhou Changming , Chen Wang , Fang Jiajie , Chen Daoyong
Published: July 2012

Here we report a facile method for the preparation of a PEO113‐b‐P4VP93 brush on gold surface with a grafting density as high as 1.32 chains/nm2; the P4VP blocks were physically adsorbed on gold surface forming an inner layer while the PEO blocks stretched towards the solution forming PEO brush. PEO113‐b‐P4VP93 micelles with P4VP core and PEO shell formed in methanol/water mixed solvents were used as the precursor. By adsorbing PEO113‐b‐P4VP93 micelles from pure water, in which the density of the micelles is the largest, maximum amount of the micelles was adsorbed onto gold surface, and the adsorbed micelles existed as individual domains on the surface. To prepare the polymer brush with a density as high as possible, we annealed the adsorbed micelles by methanol/water mixed solvent at the volume fraction of methanol (VF) of 20%, which was the proper proportion at which the core‐forming P4VP chains began to be flexible but the integrity of the micelles was remained. At this volume fraction, almost all the adsorbed micelles originally existing as individual domains were transformed into a dense polymer brush.
Growth, interaction, and positioning of microtubule asters in extremely large vertebrate embryo cells
Authors: Mitchison Timothy , Wühr Martin , Nguyen Phuong , Ishihara Keisuke , Groen Aaron , Field Christine M.
Published: July 2012

Ray Rappaport spent many years studying microtubule asters, and how they induce cleavage furrows. Here, we review recent progress on aster structure and dynamics in zygotes and early blastomeres of Xenopus laevis and Zebrafish, where cells are extremely large. Mitotic and interphase asters differ markedly in size, and only interphase asters span the cell. Growth of interphase asters occurs by a mechanism that allows microtubule density at the aster periphery to remain approximately constant as radius increases. We discuss models for aster growth, and favor a branching nucleation process. Neighboring asters that grow into each other interact to block further growth at the shared boundary. We compare the morphology of interaction zones formed between pairs of asters that grow out from the poles of the same mitotic spindle (sister asters) and between pairs not related by mitosis (non‐sister asters) that meet following polyspermic fertilization. We argue growing asters recognize each other by interaction between antiparallel microtubules at the mutual boundary, and discuss models for molecular organization of interaction zones. Finally, we discuss models for how asters, and the centrosomes within them, are positioned by dynein‐mediated pulling forces so as to generate stereotyped cleavage patterns. Studying these problems in extremely large cells is starting to reveal how general principles of cell organization scale with cell size. © 2012 Wiley Periodicals, Inc
In vitro Percutaneous Absorption of 14C‐Labeled β‐Lactone Promises Topical Delivery of New Bacterial Virulence Inhibitors
Authors: Lorenz‐Baath Katrin , Korotkov Vadim S. , Lierse von Gostomski Christoph , Sieber Stephan A.
Published: July 2012

Bacterial infections of skin and soft tissue represent a major health threat, especially if they are caused by multidrug‐resistant strains such as MRSA. Novel treatment options for topical application are urgently needed, and even if new drug candidates are identified, their properties must match the specific physical requirements of the skin in order to penetrate and reach the site of bacterial infection. β‐Lactones have been shown to eliminate bacterial virulence, but knowledge about their potential in topical treatments had thus far been lacking. Herein we present the synthesis and in‐depth investigations of skin permeation and skin distribution of a radioactive 14C‐labeled tool compound that was formulated with various basic ointments and applied to pig skin samples. Our results show that skin penetration depends highly on the nature of the formulation base. Vaseline is the most efficient ointment and is best suited for effecting maximal drug delivery within and through the stratum corneum, an important entrance barrier, and meets the required quantities for eliciting anti‐virulence effects. We are confident that the nature of these new β‐lactone virulence inhibitors confers applicability and potency for topical treatment, and will translate into a new formulation of this highly potent drug candidate for the treatment of skin and soft tissue infections.
An Efficient Synthesis of a Hydroxyethylamine (HEA) Isostere and Its α‐Aminophosphonate and Phosphoramidate Derivatives as Potential Anti‐HIV Agents
Authors: Bhattacharya Asish K. , Rana Kalpeshkumar C. , Pannecouque Christophe , De Clercq Eric
Published: July 2012

HIV protease is a promising drug target for AIDS therapy, and several potent HIV‐1 protease inhibitors have been reported to date. Although existing inhibitors exhibit high selectivity, they have also been associated with severe side effects and the possible emergence of therapeutic resistance. As HIV protease cleaves the peptide bond via a tetrahedral intermediate, various transition‐state models such as hydroxyethylamine (HEA) have been designed. We therefore pursued an efficient synthesis of an HEA isostere; this was performed with a novel one‐pot reduction–transimination–reduction reaction sequence as a key step. α‐Aminophosphonate and phosphoramidate derivatives of the HEA isostere were designed and synthesized, and all of the synthesized derivatives were assayed for their anti‐HIV activities against wild‐type and mutant HIV strains. Phosphoramidate derivative 15 a was found to be the most active of all synthesized compounds against the IIIB and RES056 strains. As phosphonates are known to exhibit physiological stability, good cell permeability, and other promising pharmacokinetic characteristics, our newly synthesized compounds have the potential as alternatives to existing therapeutics and diagnostics.
Preferences for outcomes associated with decisions to undergo or forgo genetic testing for Lynch syndrome
Authors: Kuppermann Miriam , Wang Grace , Wong Shirley , Blanco Amie , Conrad Peggy , Nakagawa Sanae , Terdiman Jonathan , Ladabaum Uri
Published: July 2012

BACKGROUND:

Current guidelines recommend offering genetic testing for Lynch syndrome to individuals whose tumors suggest this condition and to relatives of affected individuals. Little is known, however, regarding how patients view the prospect of such testing. In addition, data on preferences (utilities) for the potential outcomes of testing decisions for use in cost‐effectiveness analyses are lacking.

METHODS:

Time tradeoff utilities were elicited for 10 potential outcomes of Lynch syndrome testing decisions and 3 associated cancers from 70 participants, representing a range of knowledge about and experiences with Lynch syndrome.

RESULTS:

Highest mean utilities were assigned to scenarios in which only the assessor's sibling had Lynch‐associated colorectal cancer (ranging from 0.669 ± 0.231 to 0.760 ± 0.220). Utilities assigned to scenarios in which the assessor had Lynch‐associated colorectal cancer ranged from 0.605 ± 0.252 to 0.682 ± 0.246, whereas the lowest mean utilities were assigned to 2 of the general cancer states (0.601 ± 0.238 and 0.593 ± 0.272 for colorectal and ovarian cancer respectively). Only 43% of the sample assigned higher values to undergoing Lynch testing and receiving negative results versus forgoing Lynch testing, whereas 50% assigned higher values to undergoing rather than forgoing surgery to prevent a subsequent cancer.

CONCLUSIONS:

Genetic testing for Lynch syndrome, regardless of results, can have profound effects on quality of life; the utilities we collected can be used to incorporate these effects into cost‐effectiveness analyses. Importantly, preferences for the potential outcomes of testing vary substantially, calling into question the extent to which patients would avail themselves of such testing if it were offered to them. Cancer 2013. © 2012 American Cancer Society
Prognostic factors associated with progression of smoldering multiple myeloma to symptomatic form
Authors: Rago Angela , Grammatico Sara , Za Tommaso , Levi Anna , Mecarocci Sergio , Siniscalchi Agostina , De Rosa Luca , Felici Stefano , Bongarzoni Velia , Piccioni Anna Lina , La Verde Giacinto , Pisani Francesco , Franceschini Luca , Paviglianiti Anna Lisa , Caravita Tommaso , Petrucci Maria Teresa , De Stefano Valerio , Cimino Giuseppe ,   on behalf of the Multiple Myeloma GIMEMA‐Latium Region Working Group
Published: July 2012

BACKGROUND:

Smoldering multiple myeloma (SMM) presents a high risk of progression to symptomatic MM (sy‐MM). Herein, we analyzed some predictors of development of sy‐MM. In 144 patients with SMM, we also compared the risk of progression predicted by bone marrow plasma cell (BMPC) involvement on the bone marrow biopsy (BMB) versus bone marrow aspirates (BMA).

METHODS:

From January 1980 to July 2010, 397 patients with SMM observed in 12 centers of the Multiple Myeloma GIMEMA (Gruppo Italiano Malattie EMatologiche dell'Adulto) Latium Working Group have been analyzed. At progression to sy‐MM, the severity of clinical presentation was graded according to the need of intensive supportive care.

RESULTS:

After a median follow‐up of 135 months, the cumulative incidence of progression rates to sy‐MM were 45%, 55%, and 75% at 10, 15, and 20 years, respectively. Hemoglobin ≤12.5 g/dL, monoclonal component ≥2.5 g/dL, and BMPC ≥60% were the only parameters negatively affecting the cumulative incidence of progression. In particular, 10 of 397 (2.5%) patients with BMPC ≥60% had a 5.6‐fold increased risk of fast progression (within 2 years), which occurred with severe clinical manifestations in 62% of cases. BMB was more sensitive for the detection of BMPC involvement, even though BMA was a more reliable indicator of a rapid progression to sy‐MM.

CONCLUSIONS:

The highest risk of rapid evolution to sy‐MM and the severity of clinical manifestation at the progression suggest that SMM patients with a BMPC ≥60% should be treated soon after diagnosis. Moreover, BMPC is a more reliable index for progression to sy‐MM if assessed by BMA. Cancer 2012. © 2012 American Cancer Society.
Carbohydrate antigen 19‐9 is a prognostic and predictive biomarker in patients with advanced pancreatic cancer who receive gemcitabine‐containing chemotherapy
Authors: Bauer Todd M. , El‐Rayes Bassel F. , Li Xiaobai , Hammad Nazik , Philip Philip A. , Shields Anthony F. , Zalupski Mark M. , Bekaii‐Saab Tanios
Published: July 2012

BACKGROUND:

Carbohydrate antigen 19‐9 (CA19‐9) is a widely used biomarker in pancreatic cancer. There is no consensus on the interpretation of the change in CA19‐9 serum levels and its role in the clinical management of patients with pancreatic cancer.

METHODS:

Individual patient data from 6 prospective trials evaluating gemcitabine‐containing regimens from 3 different institutions were pooled. CA19‐9 values were obtained at baseline and after successive cycles of treatment. The objective of this study was to correlate a decline in CA19‐9 with outcomes while undergoing treatment.

RESULTS:

A total of 212 patients with locally advanced (n = 50) or metastatic (n = 162) adenocarcinoma of the pancreas were included. Median baseline CA19‐9 level was 1077 ng/mL (range, 15‐492,241 ng/mL). Groups were divided into those levels below (low) or above (high) the median. Median overall survival (mOS) was 8.7 versus 5.2 months (P = .0018) and median time to progression (mTTP) was 5.8 versus 3.7 months (P = .082) in the low versus high groups, respectively. After 2 cycles of chemotherapy, up to a 5% increase versus ≥ 5% increase in CA19‐9 levels conferred an improved mOS (10.3 vs 5.1 months, P = .0022) and mTTP (7.5 vs 3.5 months, P = 0.0005).

CONCLUSIONS:

In patients who have advanced pancreatic cancer treated with gemcitabine‐containing regimens baseline CA19‐9 is prognostic for outcome. A decline in CA19‐9 after the second cycle of chemotherapy is not predictive of improved mOS or mTTP; thus, CA19‐9 decline is not a useful surrogate endpoint in clinical trials. Clinically, a ≥ 5% rise in CA19‐9 after 2 cycles of chemotherapy serves as a negative predictive marker. Cancer 2013. © 2012 American Cancer Society.
Who makes the decision regarding the treatment of clinically localized prostate cancer–the patient or physician?
Authors: Song Lixin , Chen Ronald C. , Bensen Jeannette T. , Knafl George J. , Nielsen Matthew E. , Farnan Laura , Wallen Eric M. , Mishel Merle , Pruthi Raj S. , Mohler James L. , Godley Paul A.
Published: July 2012

BACKGROUND:

The current study examined how patients' sociodemographic, cancer‐related, and subjective affective factors impacted their role in treatment decision‐making.

METHODS:

The patient sample (N = 788) was taken from a prospective follow‐up study of a population‐based cohort. Participants included 343 African American and 445 Caucasian‐American patients with clinically localized prostate cancer. Multinomial logistic regression was used to investigate relations between the explanatory variables and the nominal 3‐level decision‐making variable: patient‐only, patient‐physician shared, and physician‐only.

RESULTS:

Approximately 41% of patients reported patient‐only decision‐making, 45% reported shared decision‐making, and 13% reported physician‐only decision‐making. The odds of patient‐only over physician‐only decision‐making were greater for younger men (vs those aged ≥ 65 years) (odds ratio [OR], 1.68; 95% confidence interval [95% CI], 1.03‐2.74), and were less for men with high (vs low) cancer aggressiveness (OR,0.29; 95% CI, 0.15‐0.55). The odds of shared over physician‐only decision‐making were less for men with high (vs low) cancer aggressiveness (OR, 0.40; 95% CI, 0.22‐0.73). Greater odds of patient‐only and shared decision‐making also were found to be associated with greater concerns about the physical impact of treatment and having enough time for decision‐making and lower scores of receiving advice from others.

CONCLUSIONS:

The findings of the current study indicate that, to facilitate a more patient‐oriented decision‐making process regarding treatment in those with clinically localized prostate cancer, clinicians need to tailor their interventions according to patient age and cancer aggressiveness, help reduce patient concerns and misconceptions regarding the physical impact of treatments, allow sufficient time for patients to consider treatment options, and assist patients in balancing advice and information received from different sources. Cancer 2013. © 2012 American Cancer Society.
Ancillary techniques on direct‐smear aspirate slides
Authors: Knoepp Stewart M. , Roh Michael H.
Published: July 2012

Numerous cytologic techniques aimed at effectively acquiring patient material for molecular testing have been proposed. Such techniques are becoming ever more important in an age of personalized medicine. In this commentary, the authors explored some more commonly proposed techniques to aid in the molecular testing of cytologic specimens. These techniques include the use of cell blocks, direct cytologic smears, filter paper storage, frozen samples, and enriched cellular techniques such as ThinPrep and cytospin preparations. Direct‐smeared slides demonstrate excellent preservation of DNA, are easy to prepare, and are amenable to immediate adequacy at the time of the fine‐needle aspiration (FNA) procedure as well as effective subsequent tumor purity estimation. Cell block methods cannot be assessed at the time of FNA and often demonstrate insufficiency, whereas filter paper and frozen techniques do not allow for the direct assessment of the presence and purity of tumor cells in the sample. Direct‐smeared slides are emerging as the most effective preparation and storage medium of cytologic material to be used for molecular testing. Their cost‐effectiveness, ease of use, and reliability have cemented them as the optimal solution for cytopathologists to fulfill the role of providing advanced molecular testing on patient samples. Cancer (Cancer Cytopathol) 2013. © 2012 American Cancer Society.
A queuing model‐based approach for the analysis of transactional memory systems
Authors: Yu Xiao , He Zhengyu , Hong Bo
Published: July 2012

In this paper, we develop an analytical model of the execution efficiency of transactional memory (TM) systems. This model employs queuing theory to analyze the impact of an essential set of TM design parameters including the conflict rate, number of conflict detection/resolution points, and implementation overhead. The model is validated via extensive experiments. To demonstrate the effectiveness of the model, we further study the performance impact of two factors. Our study shows that, for a given TM‐based program, the frequency of performing conflict detection can be carefully chosen to minimize the mean transaction completion time. Our study also demonstrated the importance of reducing implementation overhead. We expect our study to be useful for designing TM systems and applications. Copyright © 2012 John Wiley & Sons, Ltd.
ISABELA for effective in situ compression of scientific data
Authors: Lakshminarasimhan Sriram , Shah Neil , Ethier Stephane , Ku Seung‐Hoe , Chang C. S. , Klasky Scott , Latham Rob , Ross Rob , Samatova Nagiza F.
Published: July 2012

Exploding dataset sizes from extreme‐scale scientific simulations necessitates efficient data management and reduction schemes to mitigate I/O costs. With the discrepancy between I/O bandwidth and computational power, scientists are forced to capture data infrequently, thereby making data collection an inherently lossy process. Although data compression can be an effective solution, the random nature of real‐valued scientific datasets renders lossless compression routines ineffective. These techniques also impose significant overhead during decompression, making them unsuitable for data analysis and visualization, which require repeated data access.

To address this problem, we propose an effective method for In situ Sort‐And‐B‐spline Error‐bounded Lossy Abatement (ISABELA) of scientific data that is widely regarded as effectively incompressible. With ISABELA, we apply a pre‐conditioner to seemingly random and noisy data along spatial resolution to achieve an accurate fitting model that guarantees a ⩾0.99 correlation with the original data. We further take advantage of temporal patterns in scientific data to compress data by ≈ 85%, while introducing only a negligible overhead on simulations in terms of runtime. ISABELA significantly outperforms existing lossy compression methods, such as wavelet compression, in terms of data reduction and accuracy.

We extend upon our previous paper by additionally building a communication‐free, scalable parallel storage framework on top of ISABELA‐compressed data that is ideally suited for extreme‐scale analytical processing. The basis for our storage framework is an inherently local decompression method (it need not decode the entire data), which allows for random access decompression and low‐overhead task division that can be exploited over heterogeneous architectures. Furthermore, analytical operations such as correlation and query processing run quickly and accurately over data in the compressed space. Copyright © 2012 John Wiley & Sons, Ltd.
Using Time‐Resolved Electrochemical Patterning to Gain Fundamental Insight into Aryl‐Radical Surface Modification
Authors: Torbensen Kristian , Malmos Kristoffer , Kanoufi Frederic , Combellas Catherine , Pedersen Steen U. , Daasbjerg Kim
Published: July 2012

Scanning electrochemical microscopy is used to carry out local free‐radical grafting at a gold surface through mild oxidation of an aryl hydrazine. The process can be deliberately controlled by creation of a local pH gradient at the tip. Comparison of the experimental results with simulations shows that the radial expansion of the pH profile in which successful grafting can be accomplished increases with increasing generation time of OH− and with decreasing initial concentration of the grafting precursor. Furthermore, the radial expansion is faster than the nucleation of the grafting process.
Utility‐based probabilistic call admission control for complete fairness in wireless networks
Authors: Tsiropoulos G.I. , Stratogiannis D.G. , Chen Hsiao‐Hwa , Cottis P.G.
Published: July 2012

Resource reservation or the other prioritization strategies adopted by Call Admission Control (CAC) schemes in wireless networks lead to unfair resource allocation to users belonging to different service classes (SCs) due to high divergence among the respective call blocking probabilities (CBPs). In this paper, we propose dynamic optimization of probabilistic CAC (P‐CAC) schemes to assure CAC fairness among users of different SCs in wireless networks. The approach is based on users utility combined with fairness optimization, aiming at dynamically determining the probability value in the P‐CAC scheme. This optimal probability is adjusted to network ongoing traffic, CBPs of each SC, prioritization levels characterizing the SCs supported, and the users risk aversion, which reflects their behavior toward the perceived QoS. The existence and uniqueness of the optimal probability that leads to absolute fairness among the users of a wireless network are proven. Copyright © 2012 John Wiley & Sons, Ltd.