bluuebunny/crossref_metadata_2025 huggingface dataset:
3D X‐ray Microtomography Volume Correlation to Study Fatigue Crack Growth
Authors: Limodin Nathalie , Réthoré Julien , Buffière Jean‐Yves , Hild François , Ludwig Wolfgang , Rannou Johann , Roux Stéphane
Published: November 2010

Global digital volume correlation is used to analyze a series of computed tomography images of a nodular graphite cast iron specimen subjected in situ to a fatigue test. From the obtained displacement field, a specific procedure is implemented to extract stress intensity factors all along the crack front. The proposed methodology allows one to measure key parameters in fatigue crack propagation directly from 3D images.
Mechanical Properties of Friction Stir Welded Mg/Mg‐ and Mg/Al‐Joints
Authors: Klag Otmar , Wagner Guntram , Eifler Dietmar
Published: November 2010

In a mobile world weight reduction is a predominant target of innovative products. In this context appropriate joining techniques are necessary for the integration of lightweight metals in complex mechanical components. Friction stir welding (FSW) is a newly established well suited process to realize high‐quality lightweight metal joints in solid state. In a research project of WKK the friction stir weldability of similar joints using die casted AZ91‐Mg‐alloy and MRI‐Mg‐alloys was investigated. Additionally the joining of hybrid joints between AZ91 and AA5454 aluminum alloy was performed. To describe and optimize the FSW‐process the welding temperatures and welding forces were recorded online during the process. The investigations of the monotonic properties of AZ91/AZ91‐joints and MRI/MRI‐joints yielded in tensile strength values at the level of the parent materials. For dissimilar joints an extreme increase of the nugget hardness was measured. By SEM investigations and EDX element mappings it could be proved that this is caused by intermetallic phases positioned as thin interlayers in the contact area between the Mg‐ and the Al‐alloy. As a consequence, in hybrid joints failures occur predominantly along these interlayers. Finally, for similar and dissimilar welds corrosion experiments in 5 mass% NaCl solution were carried out. The investigations showed that the nugget area was more susceptible to corrosion then the base material. To understand the corrosion behavior the affected areas were analyzed using SEM and EDX.
Genotype–phenotype correlation in DTDST dysplasias: Atelosteogenesis type II and diastrophic dysplasia variant in one family
Authors: Dwyer Ellen , Hyland James , Modaff Peggy , Pauli Richard M.
Published: November 2010

Mutations in diastrophic dysplasia sulfate transporter (DTDST) cause a spectrum of autosomal recessive chondrodysplasias. In decreasing order of severity, they include processes designated as achondrogenesis type IB (ACG‐1B), atelosteogenesis type II (AO2), diastrophic dysplasia (DTD), diastrophic dysplasia variant (DTDv), and recessively inherited multiple epiphyseal dysplasia (rMED). This is the first report of an extended family with unequivocally distinct phenotypes on the DTDST spectrum. Two siblings have DTDv and their first cousin had AO2. They all share the common Finnish mutation (IVS1 + 2C>T). The two patients with DTDv have the previously reported R279W extracellular domain missense mutation. The second mutation in the patient with AO2 is c.172delA, a deletion of one nucleotide causing a previously unreported frameshift mutation. This is the first published case of an individual with a frameshift mutation combined with the Finnish mutation. These three patients provide an opportunity, in concert with a review of previous literature, to further examine the genotype–phenotype correlation of DTDST. Analysis suggests that, while the DTDST family of disorders contains at least seven different conditions, mutations in the DTDST gene, in fact, appear to cause a phenotypic continuum. Furthermore, DTDST genotype alone is an imperfect predictor of clinical severity along this continuum. © 2010 Wiley‐Liss, Inc.
Screening of human LPHN3 for variants with a potential impact on ADHD susceptibility
Authors: Domené Sabina , Stanescu Horia , Wallis Deeann , Tinloy Bradford , Pineda Daniel E. , Kleta Robert , Arcos‐Burgos Mauricio , Roessler Erich , Muenke Maximilian
Published: November 2010

Attention deficit hyperactivity disorder (ADHD) is the most common behavioral disorder in childhood, and often has effects detectable into adulthood. Advances in genetic linkage and association analysis have begun to elucidate some of the genetic factors underlying this complex disorder. Recently, we identified LPHN3, a novel ADHD susceptibility gene harbored in 4q, and showed that a LPHN3 common haplotype confers susceptibility to ADHD and predicts effectiveness of stimulant medication. Here we present the mutational analysis of the entire coding region of LPHN3 in a cohort of 139 ADHD subjects and 52 controls from across the USA. We identified 21 variants, of which 14 have been reported and 7 are novel. These include 5 missense, 8 synonymous, and 8 intronic changes. Interestingly, neither susceptibility nor protective haplotype alleles are associated with obviously significant coding region changes, or canonical splice site alterations, suggesting that non‐coding variations determining the quantity and/or quality of LPHN3 isoforms are the likely contributors to this common behavioral disorder. © 2010 Wiley‐Liss, Inc.
Untersuchung der Biologie von Naturstoffen: systematische Strukturvariation durch umgelenkte Totalsynthese
Authors: Szpilman Alex M. , Carreira Erick M.
Published: November 2010

Die systematische Modifizierung von Naturstoffen durch umgelenkte Totalsynthese ist ein leistungsfähiges Konzept mit dem Ziel, mechanistische Aspekte biologischer Aktivität zu studieren. Dieses Konzept öffnet die Tür für weitreichende Entdeckungen im Grenzbereich zwischen Biologie und Chemie. Es gründet auf der Leistungsstärke der chemischen Synthese, die sich durch die Fähigkeit auszeichnet, chemische Strukturen nahezu nach Belieben zu modifizieren. In Kombination mit innovativem Design ermöglicht seine Anwendung, einzigartige mechanistische Untersuchungen auszuführen, die entscheidend bei der Differenzierung und Validierung biologischer Hypothesen auf molekularer Ebene sein können. Dieser Aufsatz stellt klassische und aktuelle Fälle zusammen, die die vielversprechenden Perspektiven für den Synthetiker aufzeigen.
Interaction of ethyltrichlorostannane withN,N‐dimethylamides ofO‐ trimethylsilyl‐α‐hydroxyacids
Authors: Gruener Sergey V. , Airapetyan David V. , Korlyukov Alexander A. , Shipov Alexander G. , Baukov Yuri I. , Petrosyan Valery S.
Published: November 2010

Reactions of ethyltrichlorostannane withN,N‐dimethylamides of 2‐(trimethylsilyl)glycolic (2a), 2(S)‐lactic [(S)‐2b] and mandelic (2c) acids led to the first representatives of tin(IV)O,O‐monochelates containing the five‐membered SnOCC(O) monoanionic chelate cycles as a result of the substitution of one halogen atom. According to the X‐ray data, in the case of the derivatives of glycolic and mandelic acids, the isolated complexes have dimeric structures {EtCl2Sn[OCH(R)C(O)NMe2]}2[R = H (3a), Ph (3c)] with the bridge oxygen atoms and hexacoordinated tin atoms. By contrast, in the case of the derivative of lactic acid (S)‐2b, the product of the reaction is the cationic–anionic complex 2EtCl2Sn[OCH(Me)C(O)NMe2]·HCl (4), which is the adduct of two molecules of the respective monomeric complex with HCl. In addition,N,N‐dimethylamide ofO‐triethylstannylglycolic acid (5) with tetracoordinated tin is described. To analyze the stability of complex 4, the experimental charge density study and the quantum chemical calculations [PBE0/6‐311G(d,p)] were carried out. Topological analysis of the experimental and calculated electron density distribution functions allowed us to conclude that the strong OH···O bond with pronounced covalent contribution stabilizes the dimeric structure of 4 to a greater extent than the bridged SnCl bonds. Copyright © 2010 John Wiley & Sons, Ltd.
A Method to Calculate the Volume of Palatine Tonsils
Authors: Prim M.P. , De Diego J.I. , García‐Bermúdez C. , Pérez‐Fernández E. , Hardisson D.
Published: November 2010

The purpose of this study was to obtain a mathematical formula to calculate the tonsillar volume out of its measurements assessed on surgical specimens. Thirty consecutive surgical specimens of pediatric tonsils were studied. The maximum lengths (“a”), widths (“b”), and depths (“c”) of the dissected specimens were measured in millimeters, and the volume of each tonsil was measured in milliliters. One‐sample Kolmogorov–Smirnov test was used to check the normality of the sample. To calculate the reproducibility of the quantitative variables, intraclass correlation coefficients were used. Two formulas with high reproducibility (coefficient R between 0.75 and 1) were obtained: 1) [a*b*c* 0.5236] with R = 0.8688; and 2) [a*b*b* 0.3428] with R = 0.9073. It is possible to calculate the volume of the palatine tonsils in surgical specimens precisely enough based on their three measures, or their two main measures (length and width). Anat Rec, 2010. © 2010 Wiley‐Liss, Inc.
The Tail of Tyrannosaurus: Reassessing the Size and Locomotive Importance of the M. caudofemoralis in Non‐Avian Theropods
Authors: Persons W. Scott , Currie Philip J.
Published: November 2010

Unlike extant birds and mammals, most non‐avian theropods had large muscular tails, with muscle arrangements similar to those of modern reptiles. Examination of ornithomimid and tyrannosaurid tails revealed sequential diagonal scarring on the lateral faces of four or more hemal spines that consistently correlates with the zone of the tail just anterior to the disappearance of the vertebral transverse processes. This sequential scarring is interpreted as the tapering boundary between the insertions of the M. caudofemoralis and the M. ilioischiocaudalis. Digital muscle reconstructions based on measurements of fossil specimens and dissections of modern reptiles showed that the M. caudofemoralis of many non‐avian theropods was exceptionally large. These high caudofemoral mass estimates are consistent with the elevation of the transverse processes of the caudal vertebra above the centrum, which creates an enlarged hypaxial region. Dorsally elevated transverse processes are characteristic of even primitive theropods and suggest that a large M. caudofemoralis is a basal characteristic of the group. In the genus Tyrannosaurus, the mass of the M. caudofemoralis was further increased by dorsoventrally lengthening the hemal arches. The expanded M. caudofemoralis of Tyrannosaurus may have evolved as compensation for the animal's immense size. Because the M. caudofemoralis is the primary hind limb retractor, large M. caudofemoralis masses and the resulting contractile force and torque estimates presented here indicate a sizable investment in locomotive muscle among theropods with a range of body sizes and give new evidence in favor of greater athleticism, in terms of overall cursoriality, balance, and turning agility. Anat Rec,, 2010. © 2010 Wiley‐Liss, Inc.
Regioselective Ring‐Opening of Amino Acid‐Derived Chiral Aziridines: an Easy Access tocis‐2,5‐Disubstituted Chiral Piperazines
Authors: Samanta Krishnananda , Panda Gautam
Published: November 2010

An efficient four‐step synthetic strategy forcis‐2,5‐disubstituted chiral piperazines derived from amino‐acid‐based aziridines is described. The key steps in this strategy are the highly regioselective boron trifluoride diethyl etherate (BF3⋅OEt2)‐mediated ring‐opening of less‐reactiveN‐Ts chiral aziridines by α‐amino acid methyl ester hydrochloride followed by Mitsunobu cyclization. This protocol has been used in an attempt to construct the piperazine core framework of natural product (+)‐piperazinomycin.
Self‐Assembled Gels for Biomedical Applications
Authors: Truong Warren Ty , Su Yingying , Meijer Joris T. , Thordarson Pall , Braet Filip
Published: November 2010

Natural and synthetic gel‐like materials have featured heavily in the development of biomaterials for wound healing and other tissue‐engineering purposes. More recently, molecular gels have been designed and tailored for the same purpose. When mixed with, or conjugated to therapeutic drugs or bioactive molecules, these materials hold great promise for treating/curing life‐threatening and degenerative diseases, such as cancer, osteoarthritis, and neural injuries. This focus review explores the latest advances in this field and concentrates on self‐assembled gels formed under aqueous conditions (i.e., self‐assembled hydrogels), and critically compares their performance within different biomedical applications, including three‐dimensional cell‐culture studies, drug delivery, and tissue engineering. Although stability and toxicity issues still need to be addressed in more detail, it is clear from the work reviewed here that self‐assembled gels have a bright future as novel biomaterials.
Analysis of an artificially selected GS‐NS0 variant with increased resistance to apoptosis
Authors: Browne Susan M. , Al‐Rubeai Mohamed
Published: November 2010

Heterogeneity in gene expression and phenotypic traits is an inherent feature within the “clonal” cell lines used for biopharmaceutical production. This feature can allow the selection of cell lines with improved phenotypes and adaptation to growth under preferential conditions to improve productivity or provide a platform to study the molecular basis of improved characteristics. A repeated process of extended batch culture of a recombinant antibody producing GS‐NS0 myeloma cell line generated a stable variant cell line displaying increased resistance to both environmental stresses and chemical apoptosis inducers, and resulted in extended culture viability and increased antibody production. An interesting feature of the variant cell line was an altered metabolic state with consumption of lactate as the culture progressed. The variant cell line also showed altered expression of proteins associated with autophagy suggesting a role for this process in extending cell survival in culture. Targeted transcriptomic analysis was carried out on the parental and variant cell lines using a qRT‐PCR array containing a panel of apoptosis‐associated genes to elucidate both the predominant apoptotic pathways in the NS0 cell line with batch culture progression, and the altered gene expression contributing to increased survival in the variant line. Results indicated a balance between pro‐ and anti‐apoptotic signaling is triggered with the onset of cell death in the NS0 cell line. Pro‐survival pathways such as NFκB signaling and the unfolded protein response were implicated along with death receptor, endoplasmic reticulum stress and p53 mediated apoptotic pathways. The identification of altered gene expression in the variant cell line also provides several potential targets for cell engineering strategies to create improved cell lines for production. Biotechnol. Bioeng. 2011; 108:880–892. © 2010 Wiley Periodicals, Inc.
Evaluating Factors That Influence Microbial Synthesis Yields by Linear Regression with Numerical and Ordinal Variables
Authors: Colletti Peter F. , Goyal Yogesh , Varman Arul M. , Feng Xueyang , Wu Bing , Tang Yinjie J.
Published: November 2010

In the production of chemicals via microbial fermentation, achieving a high yield is one of the most important objectives. We developed a statistical model to analyze influential factors that determine product yield by compiling data obtained from engineered Escherichia coli developed within last 10 years. Using both numerical and ordinal variables (e.g., enzymatic steps, cultivation conditions, and genetic modifications) as input parameters, our model revealed that cultivation modes, nutrient supplementation, and oxygen conditions were the three significant factors for improving product yield. Generally, the model showed that product yield decreases as the number of enzymatic steps in the biosynthesis pathway increases (7–9% loss of yield per enzymatic step). Moreover, overexpression of enzymes or removal of competitive pathways (e.g., knockout) does not necessarily result in an amplification of product yield (P‐value >0.1), possibly because of limited capacity in the biosynthesis pathway to accommodate an increase in flux. The model not only provides general guidelines for metabolic engineering and fermentation processes, but also allows a priori estimation and comparison of product yields under designed cultivation conditions. Biotechnol. Bioeng. 2011; 108:893–901. © 2010 Wiley Periodicals, Inc.
Enzyme identification and development of a whole‐cell biotransformation for asymmetric reduction ofo‐chloroacetophenone
Authors: Kratzer Regina , Pukl Matej , Egger Sigrid , Vogl Michael , Brecker Lothar , Nidetzky Bernd
Published: November 2010

Chiral 1‐(o‐chlorophenyl)‐ethanols are key intermediates in the synthesis of chemotherapeutic substances. Enantioselective reduction ofo‐chloroacetophenone is a preferred method of production but well investigated chemo‐ and biocatalysts for this transformation are currently lacking. Based on the discovery thatCandida tenuisxylose reductase convertso‐chloroacetophenone with useful specificity (kcat/Km = 340 M−1 s−1) and perfectS‐stereoselectivity, we developed whole‐cell catalysts fromEscherichia coliandSaccharomyces cerevisiaeco‐expressing recombinant reductase and a suitable system for recycling of NADH.E. colisurpassedS. cerevisiaesixfold concerning catalytic productivity (3 mmol/g dry cells/h) and total turnover number (1.5 mmol substrate/g dry cells).o‐Chloroacetophenone was unexpectedly “toxic,” and catalyst half‐life times of only 20 min (E. coli) and 30 min (S. cerevisiae) in the presence of 100 mM substrate restricted the time of batch processing to maximally ∼5 h. Systematic reaction optimization was used to enhance the product yield (≤60%) ofE. colicatalyzed conversion of 100 mMo‐chloroacetophenone which was clearly limited by catalyst instability. Supplementation of external NAD+(0.5 mM) to cells permeabilized with polymyxin B sulfate (0.14 mM) resulted in complete conversion providing 98 mMS‐1‐(o‐chlorophenyl)‐ethanol. The strategies considered for optimization of reduction rate should be generally useful, however, especially under process conditions that promote fast loss of catalyst activity. Biotechnol. Bioeng. 2011; 108:797–803. © 2010 Wiley Periodicals, Inc.
Characterization of the proteases involved in the N‐terminal clipping of glucagon‐like‐peptide‐1‐antibody fusion proteins
Authors: Dorai Haimanti , Santiago Aleixo , Campbell Marguerite , Tang Q. Mike , Lewis Michael J. , Wang Yonghui , Lu Qiao‐Zhen , Wu Shiaw‐Lin , Hancock William
Published: November 2010

In an attempt to develop high producing mammalian cell lines expressing glucagon‐like‐peptide‐1‐antibody fusion proteins (GLP‐1), we have noted that the N‐terminal GLP‐1 portion of the fusion protein was susceptible to proteolytic degradation during cell culture, which resulted in an inactive product. The majority of the N‐terminal clipped product appeared to be due to the removal of the entire biologically active peptide (30 amino acids) from the intact molecule. A number of parameters that influenced the degradative process were investigated. Additionally, protease inhibitors specific for each class of protease were tested. Results suggested that one or more serine‐threonine class of protease(s) were involved in this process and inhibitors that are specific for this class of protease, including benzamidine hydrochloride could significantly inhibit the proteolytic degradation of the fusion proteins. Identification of the specific proteases involved in this process by shotgun proteomics methodology will pave the way for engineering the CHOK1SV cell line which will serve as a superior host for the production of future fusion protein products. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011
High‐density microcarrier cell cultures for influenza virus production
Authors: Bock A. , Schulze‐Horsel J. , Schwarzer J. , Rapp E. , Genzel Y. , Reichl U.
Published: November 2010

Influenza virus A/PR/8/34 virus propagation in adherent Madin–Darby canine kidney cells in high‐density microcarrier cultures is described. To improve virus yields, perfusion and repeated fed‐batch modes were applied using cell‐specific feed rates. Cell densities up to 1.1 × 107cells/mL were achieved. Cell‐specific virus yields in high‐density cultures were at similar levels compared with standard, low‐density cultivations. In the average 2,400 and 3,300 virions per cell were obtained for two variants of the virus strain A/PR/8/34, PR8‐National Institute for Biological Standards and Control (NIBSC) and PR8‐Robert Koch Institute, respectively. Maximum virus titer (HA activity = 1,778 HAU/100 μL) for virus variant PR8‐NIBSC was obtained for a cultivation infected before maximum cell concentration was reached. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011
Offline glucose biomonitoring in yeast culture by polyamidoamine/ cysteamine‐modified gold electrodes
Authors: Yuksel Merve , Akin Mehriban , Geyik Caner , Demirkol Dilek Odaci , Ozdemir Caglar , Bluma Arne , Höpfner Tim , Beutel Sascha , Timur Suna , Scheper Thomas
Published: November 2010

This article deals with the use of pyranose oxidase (PyOx) and glucose oxidase (GOx) enzymes in amperometric biosensor design and their application in monitoring fermentation processes with the combination of flow injection analysis (FIA). The amperometric studies were carried out at −0.7 V by following the oxygen consumption due to the enzymatic reactions for both batch and FIA modes. Optimization studies (enzyme amounts and pH) and analytical parameters such as linearity, repeatability, effect of interference, storage, and operational stabilities have been studied. Under optimized conditions, for the PyOx‐based biosensor, linear graph was obtained from 0.025 to 0.5 mM glucose in phosphate buffer (50 mM) at pH 7.0 with the equation of y = 3.358x + 0.028 and R2 = 0.998. Linearity was found to be 0.01–1.0 mM in citrate buffer (50 mM and pH 4.0) with the equation of y = 1.539x + 0.181 and R2 = 0.992 for the GOx biosensor. Finally, these biosensor configurations were further evaluated in a conventional flow injection system. Results from batch experiments provide a guide to design sensitive, stable, and interference‐free biosensors for FIA mode. Biosensor stability, dynamic range, and repeatability were also studied in FIA conditions, and the applicability for the determination of glucose in fermentation medium could be successfully demonstrated. The FIA‐combined glucose biosensor was used for the offline monitoring of yeast fermentation. The obtained results correlated well with HPLC measurements. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011
Virtual radiation detection and measurement laboratory
Authors: Tiftikci Ali , Kocar Cemil
Published: November 2010

Simulation of alpha, beta and gamma radiation detection and measurement experiments which are part of nuclear physics laboratory courses was realized with Monte‐Carlo method and JAVA Programming Language. As it is well known, establishing this type of laboratory is very expensive. At the same time, highly radioactive sources used in some experiments carry risks for students and also for experimentalists. By taking into consideration these problems, the aim of this study is to setup a virtual radiation laboratory with minimum cost and to speed up the training in radiation physics for students. Bearing in mind the training capabilities of the software is coded to allow the users creating their own experimental setup and searching for experimental setup suitable for a specific type of experiment. As an example, mixed source isotope identification with high purity germanium, bismuth germanate, and sodium iodine detectors is studied in this paper and the importance of energy resolution of a detector in such an experiment is discussed. Software shows the nature of radiation and radiation transport with the help of Monte‐Carlo method. In this software, experimental parameters can be changed manually by the user and experimental results can be followed in an multi channel analyzer (MCA) or an single channel analyzer (SCA). Results obtained in experiments can be analyzed by these MCA or SCA panels. Virtual radiation laboratory which is developed in this study with reliable results and unlimited experimentation capability seems a useful educational tool. © 2010 Wiley Periodicals, Inc. Comput Appl Eng Educ 21: 550–560, 2013
Cytotoxic Sesquiterpenes from Magnolia kachirachirai
Authors: Chang Hsun‐Shuo , Lee Shiow‐Ju , Yang Cheng‐Wei , Chen Ih‐Sheng
Published: November 2010

Bioassay‐guided fractionation of the root wood of Magnolia kachirachirai (Kanehira & Yamamoto) Dandy (Magnoliaceae) led to the isolation of three new compounds, kachiraterpenol (1), (E)‐2,3‐bis(4‐hydroxy‐3‐methoxyphenyl)prop‐2‐enal (15), and kachiranol (19), together with 27 known compounds, of which 4,4′‐dihydroxy‐3,3′‐dimethoxybenzophenone (16) was isolated for the first time from a natural source. Their structures were elucidated by spectroscopic analysis. Two of these isolates, costunolide (2) and dehydrosaussurea lactone (4), showed cytotoxic properties against MCF‐7, NCI‐H460, and SF‐268 cancer cell lines in vitro.
Linking Chemical and Microbial Diversity in Marine Sponges: Possible Role for Poribacteria as Producers of Methyl‐Branched Fatty Acids
Authors: Hochmuth Thomas , Niederkrüger Holger , Gernert Christine , Siegl Alexander , Taudien Stefan , Platzer Matthias , Crews Phillip , Hentschel Ute , Piel Jörn
Published: November 2010

Many marine sponges contain massive numbers of largely uncultivated, phylogenetically diverse bacteria that seem to be important contributors to the chemistry of these animals. Insights into the diversity, origin, distribution, and function of their metabolic gene communities are crucial to dissect the chemical ecology and biotechnological potential of sponge symbionts. This study reveals a sharp dichotomy between high and low microbial abundance sponges with respect to polyketide synthase (PKS) gene content, the presence of methyl‐branched fatty acids, and the presence of members of the symbiotic candidate phylum “Poribacteria”. For the symbiont‐rich sponge Cacospongia mycofijiensis, a source of the tubulin‐inhibiting fijianolides (=laulimalides), near‐exhaustive large‐scale sequencing of PKS gene‐derived PCR amplicons was conducted. Although these amplicons exhibit high diversity at the sequence level, almost all of them belong to a single, architecturally unique group of PKSs present in “Poribacteria” and are proposed to synthesize methyl‐branched fatty acids. Three components of this PKS were studied in vitro, providing initial insight into its biochemistry.
Structural Characteristics, Stability, and Activity of (VO)2P2O7 and VO(PO3)2 Catalysts in p‐Cymene Liquid‐Phase Oxidation
Authors: Makgwane Peter R. , Ferg Ernst E. , Zeelie Ben
Published: November 2010

The post‐reaction structural characteristics of VO(PO3)2 and (VO)2P2O7 catalysts and their reusability in liquid‐phase oxidation of p‐cymene to tertiary cymene hydroperoxide (TCHP) are investigated and characterized. The VO(PO3)2 structure remains unchanged after being used for extended reaction times, whereas (VO)2P2O7 undergoes structural changes back to its precursor phase, VOHPO4⋅0.5 H2O, that affect its catalytic properties. The structure of the (VO)2P2O7 that has undergone phase changes is successfully restored by calcination under N2 flow at 750 °C for 2 h. Fresh and used catalysts show different particle morphologies, indicating that the reaction medium influences the microstructure. Both catalysts show considerable reusability with (VO)2P2O7 showing slight gradual deactivation. Taking into account the characterization and catalytic results obtained, the slight (VO)2P2O7 deactivation can probably be ascribed to the adsorption of organic compounds on the catalyst surface, which appears to initiate structural transformation of the (VO)2P2O7 catalyst under oxidation reaction conditions for extended reaction times. The VO(PO3)2 and (VO)2P2O7 catalysts showed to be effective for synthesis of the industrially important intermediate TCHP, a precursor to p‐cresol in liquid‐phase oxidation reactions.
Luminescent Porous Silica Fibers as Drug Carriers
Authors: Hou Zhiyao , Zhang Cuimiao , Li Chunxia , Xu Zhenhe , Cheng Ziyong , Li Guogang , Wang Wenxin , Peng Chong , Lin Jun
Published: November 2010

Luminescent and porous silica fibers have been successfully prepared by using the electrospinning process. The obtained multifunctional silica fibers, which possess a porous structure and display blue luminescence, can serve as a drug delivery host carrier, using ibuprofen (IBU) as a model drug, allowing the investigation of storage/release properties. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier‐transform infrared spectroscopy (FT‐IR), N2 adsorption/desorption, photoluminescence (PL) spectra, and kinetic decay were used to characterize the structural, morphological, and optical properties of the as‐obtained samples. The results reveal that the multifunctional silica materials exhibit an irregular porous structure, and display a fiberlike morphology with dimensions of several hundred nanometers in width and several millimeters in length. The obtained silica fibers exhibit an intense broad bluish emission, which might be attributed to impurities and/or defects in the silica fibers. The IBU‐loaded silica fiber system shows blue luminescence under UV irradiation and controlled release behavior for IBU. In addition, the emission intensities of silica fibers in the drug carrier system vary with the released amount of IBU, thus allowing the drug release to be easily tracked and monitored by the change of the luminescence intensity.
Magnetic Electrochemiluminescent Fe3O4/CdSe–CdS Nanoparticle/Polyelectrolyte Nanocomposite for Highly Efficient Immunosensing of a Cancer Biomarker
Authors: Jie Guifen , Wang Lei , Zhang Shusheng
Published: November 2010

Magnetic electrochemiluminescent Fe3O4/CdSe–CdS nanoparticle/polyelectrolyte nanostructures have been synthesized and used to fabricate an electrochemiluminescence (ECL) immunosensor for the detection of carcinoembryonic antigen (CEA). CEA is a protein used as a biomarker for several cancers; particularly, to monitor response to treatment in colon and rectal cancer patients. The nanocomposites can be easily separated and firmly attached to an electrode owing to their excellent magnetic properties. This represents a promising advantage for bioassay applications. More importantly, the nanostructures exhibit intense and stable ECL emissions in neutral solution, which makes them ideal for ECL immunosensing. The 3‐aminopropyltriethoxysilane (APS) polyelectrolyte shell on the nanostructure surface not only enhances the intensity and stability of the ECL signal, but also acts as a crosslinker for immunosensor fabrication. A CEA antibody immobilized onto a nanocomposite/APS/electrode with gold nanoparticles comprises the ECL immunosensor. The principle of ECL detection for CEA is based on a change in steric hindrance after immunoreaction, which leads to a decrease in ECL intensity. A wide detection range (0.064 pg ml−1–10 ng ml−1) and low detection limit (0.032 pg ml−1) are achieved. The immunosensor is highly sensitive and selective, and exhibits excellent stability and good reproducibility. It thus has great potential for clinical protein detection. In particular, this approach uses a novel class of bifunctional nanocomposites that display both intense ECL and excellent magnetism, which renders them suitable for a large range of bioassay applications.
Mechanistic Insight into the Reactivity of Oxotransferases by Novel Asymmetric Dioxomolybdenum(VI) Model Complexes
Authors: Mayilmurugan Ramasamy , Harum Bastian N. , Volpe Manuel , Sax Alexander F. , Palaniandavar Mallayan , Mösch‐Zanetti Nadia C.
Published: November 2010

The asymmetric molybdenum(VI) dioxo complexes of the bis(phenolate) ligands 1,4‐bis(2‐hydroxybenzyl)‐1,4‐diazepane, 1,4‐bis(2‐hydroxy‐4‐methylbenzyl)‐1,4‐diazepane, 1,4‐bis(2‐hydroxy‐3,5‐dimethylbenzyl)‐1,4‐diazepane, 1,4‐bis(2‐hydroxy‐3,5‐di‐tert‐butylbenzyl)‐1,4‐diazepane, 1,4‐bis(2‐hydroxy‐4‐flurobenzyl)‐1,4‐diazepane, and 1,4‐bis(2‐hydroxy‐4‐chlorobenzyl)‐1,4‐diazepane (H2(L1)–H2(L6), respectively) have been isolated and studied as functional models for molybdenum oxotransferase enzymes. These complexes have been characterized as asymmetric complexes of type [MoO2(L)] 1–6 by using NMR spectroscopy, mass spectrometry, elemental analysis, and electrochemical methods. The molecular structures of [MoO2(L)] 1–4 have been successfully determined by single‐crystal X‐ray diffraction analyses, which show them to exhibit a distorted octahedral coordination geometry around molybdenum(VI) in an asymmetrical cis‐β configuration. The MoOoxo bond lengths differ only by ≈0.01 Å. Complexes 1, 2, 5, and 6 exhibit two successive MoVI/MoV (E1/2, −1.141 to −1.848 V) and MoV/MoIV (E1/2, −1.531 to −2.114 V) redox processes. However, only the MoVI/MoV redox couple was observed for 3 and 4, suggesting that the subsequent reduction of the molybdenum(V) species is difficult. Complexes 1, 2, 5, and 6 elicit efficient catalytic oxygen‐atom transfer (OAT) from dimethylsulfoxide (DMSO) to PMe3 at 65 °C at a significantly faster rate than the symmetric molybdenum(VI) complexes of the analogous linear bis(phenolate) ligands known so far to exhibit OAT reactions at a higher temperature (130 °C). However, complexes 3 and 4 fail to perform the OAT reaction from DMSO to PMe3 at 65 °C. DFT/B3LYP calculations on the OAT mechanism reveal a strong trans effect.
Photocontrolled Manipulation of a Microscale Object: A Rotational or Translational Mechanism
Authors: Kausar Abu , Nagano Hiroto , Kuwahara Yutaka , Ogata Tomonari , Kurihara Seiji
Published: November 2010

In this paper the photocontrolled manipulation of solid materials on the surface of a liquid crystalline thin film is described. Three different types of films namely cholesteric liquid crystal (ChLC), compensated nematic liquid crystal (NLC) and nematic LC were used. The rotational and translational manipulation of the microscale solid object was induced by irradiation of light and mode of manipulation (either translational or rotational) was changed by changing the isomer of the azobenzene compound used to make the film. Rotational motion of the object was observed on the ChLC and compensated NLC films containing chirally pure azobenzene compound. The direction of rotational motion was controlled either by changing the optical isomer of the chiral azobenzene or by changing the irradiating light (from ultraviolet to visible). When racemic mixture of the chiral azobenzene compound was used, a translational motion of the object was observed. Even though the direction of the translational motion can be controlled by controlling irradiation position, more facile and precise manipulation of the objects was possible by spatially controlled irradiation of Ar+laser and diode UV laser.
Solvent‐ and Temperature‐Dependent Functionalisation of Enantioenriched Aziridines
Authors: de Ceglie Maria Carolina , Musio Biagia , Affortunato Francesco , Moliterni Anna , Altomare Angela , Florio Saverio , Luisi Renzo
Published: November 2010

A highly stereo‐ and regioselective functionalisation of chiral non‐racemic aziridines is reported. By starting from a parent enantioenriched aziridine and finely tuning the reaction conditions, it is possible to address the regio‐ and stereoselectivity of the lithiation/electrophile trapping sequence, thereby allowing the preparation of highly enantioenriched functionalised aziridines. From chiral N‐alkyl trans‐2,3‐diphenylaziridines (S,S)‐1 a,b, two differently configured chiral aziridinyllithiums could be generated (trans‐1 a,b‐Li in toluene and cis‐1 a,b‐Li in THF), thus disclosing a solvent‐dependent reactivity that is useful for the synthesis of chiral tri‐substituted aziridines with different stereochemistry. In contrast, chiral aziridine (S,S)‐1 c showed a temperature‐dependent reactivity to give chiral ortho‐lithiated aziridine 1 c‐ortho‐Li at −78 °C and α‐lithiated aziridine 1 c‐α‐Li at 0 °C. Both lithiated intermediates react with electrophiles to give enantioenriched ortho‐ and α‐functionalised aziridines. The reaction of all the lithiated aziridines with carbonyl compounds furnished useful chiral hydroxyalkylated derivatives, the stereochemistry of which was ascertained by X‐ray and NMR spectroscopic analysis. The usefulness of chiral non‐racemic functionalised aziridines has been demonstrated by reductive ring‐opening reactions furnishing chiral amines that bear quaternary stereogenic centres and chiral 1,2‐, 1,3‐ and 1,5‐aminoalcohols. It is remarkable that the solvent‐dependent reactivity observed with (S,S)‐1 a,b permits the preparation of both the enantiomers of amines (11 and ent‐11) and 1,2‐aminoalcohols (13 and ent‐13) starting from the same parent aziridine. Interestingly, for the first time, a configurationally stable chiral α‐lithiated aziridine (1 c‐α‐Li) has been generated at 0 °C. In addition, ortho‐hydroxyalkylated aziridines have been easily converted into chiral aminoalkyl phthalans, which are useful building blocks in medicinal chemistry.
Color and women hitchhikers' attractiveness: Gentlemen drivers prefer red
Authors: Guéguen* Nicolas
Published: November 2010

Research has shown that with some nonhuman primates, red is associated with greater sexual attractiveness of females. Five female confederates in their early 20s posed as hitchhikers wearing T‐shirts of different colors (black, white, red, blue, green, or yellow). It was found that the women wearing red solicited a higher response in the number of male drivers who stopped to offer a ride. No color effect was found when considering the behavior of female drivers. © 2010 Wiley Periodicals, Inc. Col Res Appl, 2012
Mechanism of Proton Relaxation for Enzyme‐Manipulated, Multicomponent Gold–Magnetic Nanoparticle Chains
Authors: Jaganathan Hamsa , Gieseck Richard L. , Hudson Katherine , Kellogg Michael , Ramaswamy Aneesh K. , Raver Kimberly E. , Smith Tyler , Vacchiano Ashley N. , Wager Andrew , Ivanisevic Albena
Published: November 2010

Longitudinal and transverse relaxation times of multicomponent nanoparticle (NP) chains are investigated for their potential use as multifunctional imaging agents in magnetic resonance imaging (MRI). Gold NPs (ca. 5 nm) are arranged linearly along double‐stranded DNA, creating gold NP chains. After cutting gold NP chains with restriction enzymes (EcoRI or BamHI), multicomponent NP chains are formed through a ligation reaction with enzyme‐cut, superparamagnetic NP chains. We evaluate the changes in relaxation times for different constructs of gold–iron oxide NP chains and gold–cobalt iron oxide NP chains using 300 MHz 1H NMR. In addition, the mechanism of proton relaxation for multicomponent NP chains is examined. The results indicate that relaxation times are dependent on the one‐dimensional structure and the amount of superparamagnetic NP chains present in the multicomponent constructs. Multicomponent NP chains arranged on double‐stranded DNA provide a feasible method for fabrication of multifunctional imaging agents that improve relaxation times effectively for MRI applications.
Synthesis and photoluminescence properties of bundle‐like CdS nanostructures assembled by high‐quality nanorods
Authors: Xuan Zongwei , Chao Kun , Lu Lude , Li Guicun
Published: November 2010

Bundle‐like cadmium sulfide (CdS) nanostructures assembled by high‐quality nanorods have been successfully synthesized on a large scale via a facile solvothermal route in a mixed solvent of ethylenediamine and dodecanethiol. The typical lengths of bundle‐like CdS nanostructures are several tens of micrometers, and the diameters and lengths of CdS nanorods are about 50–70 nm and several micrometers, respectively. The influence of the concentration of dodecanethiol on the morphologies of CdS nanostructures has been investigated carefully. Photoluminescence spectra (PL) of CdS nanostructures reveal that the bundle‐like CdS nanostructures exhibited two fluorescence emission peaks centered at 495nm (2.51 eV) and 522 nm (2.38 eV) as the excitation wavelength is 405 nm. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Catalytic Fast Pyrolysis of Cellulose to Prepare Levoglucosenone Using Sulfated Zirconia
Authors: Wang Zhi , Lu Qiang , Zhu Xi‐Feng , Zhang Ying
Published: November 2010

Sulfated zirconia was employed as catalyst for fast pyrolysis of cellulose to prepare levoglucosenone (LGO), a very important anhydrosugar for organic synthesis. The yield and the selectivity of LGO were studied in a fixed‐bed reactor at different temperatures and cellulose/catalyst mass ratios. The experiments of catalyst recycling were also carried out. The results displayed that from 290 to 400 °C, the liquid and solid accounted for more than 95 wt % of products, and the higher temperature led to more liquid and less solid products. The introduction of SO42−/ZrO2 could promote cellulose conversion and LGO production. The temperature had a similar effect on the yield and selectivity of LGO at different cellulose/catalyst mass ratios. The maximum yield was obtained at 335 °C. Although the structure of the parent ZrO2 was retained after recycles, which was confirmed by X‐ray diffraction and N2 adsorption–desorption measurements, the activity of SO42−/ZrO2 could only be partially recovered by simply calcination. The catalytic activity decrease could be mainly attributed to SO42− leaching, and the activity could be restored by further impregnation of H2SO4.
Flowerlike PbS Microcrystals: Citric Acid Assisted Synthesis, Shape Evolution, and Electrical Conductivities
Authors: Jin Rencheng , Chen Gang , Wang Qun , Pei Jian , Wang Gang , Wang Lin
Published: November 2010

Lead sulfide (PbS) with various morphologies including flowerlike, microsphere, multipod, six‐armed star, and truncated octahedron has been synthesized selectively under hydrothermal conditions. The synthesis procedure variables such as concentration of the citric acid (CA), kinds of surfactant, reaction temperature, and reaction time were observed to influence the resultant shape of PbS microstructures. The structure and morphology of the obtained products were characterized by means of X‐ray diffraction (XRD), field‐emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy‐dispersive X‐ray spectroscopy (EDS), and Fourier transform infrared spectroscopy (FTIR) analysis. On the basis of the time‐dependent experimental data, the possible formation mechanism related to facet‐selective growth and dissolution–recrystallization was presented. Furthermore, the electrical conductivities for different morphologies of PbS were measured to investigate the possible effect of morphology on the electrical conductivity.
Di(2‐pyridyl) Ketone Complexes of CuI‐ and CuII‐Containing Iodide and Thiocyanate Ligands: An Unusual Case of a Mixed‐Aldol Condensation
Authors: Szpakolski Katherine B. , Latham Kay , Rix Colin J. , White Jonathan M.
Published: November 2010

Complexes containing di(2‐pyridyl) ketone (dpk) as a bi‐ (N,N) and tridentate (N,N,O) ligand have been synthesised1,2 and characterized by spectral and structural studies. Products 1 and 2 are polymorphs of the polymeric copper(I) complex [Cu(dpk)(NCS)]n containing dpk with thiocyanate anions which bridge to form a one‐dimensional continuous polymer chain. The novel dinuclear copper(II) complex [Cu2(dpk·acetone)2(NCS)2] (3) was formed when 1 and 2 were allowed to stand in the supernatant. In this instance it appears that a transition‐metal‐promoted aldol condensation has occurred between the solvent acetone and the ketone carbonyl of dpk to produce the novel ligand, dpk·acetone. Product 3 contains two five‐coordinate copper(II) ions, both with trigonal bipyramidal coordination, bridged through deprotonated hydroxy groups on each dpk·acetone. A chemical rationalisation for the formation of 3 is proposed. The dinuclear copper(I) complex [Cu2(dpk)2I2] (4) is also reported, which contains two four‐coordinate copper(I) ions that are bridged together through iodide ions.
Applying Biocatalysis to the Synthesis of Diastereomerically Enriched Cyanohydrin Mannosides
Authors: Hietanen Ari , Ekholm Filip S. , Leino Reko , Kanerva Liisa T.
Published: November 2010

Fully acetylated D‐ and L‐α‐mannosylacetaldehydes have been prepared and used as substrates to produce the corresponding cyanohydrins or cyanohydrin acetates with (2S) or (2R) configuration, respectively, at the cyanohydrin moiety. The (R)‐oxynitrilase‐catalysed synthesis and lipase‐catalysed diastereomeric kinetic and dynamic kinetic resolutions were investigated. Sequential catalysis with almond meal [an economic source of (R)‐oxynitrilase] and Burkholderia cepacia lipase was shown to be a straightforward method that yielded the four diastereomeric target cyanohydrins, the absolute configurations of which were confirmed by 1H NMR analysis.
P‐Stereogenic Ferrocene‐Based (Trifluoromethyl)phosphanes: Synthesis, Structure, Coordination Properties and Catalysis
Authors: Sondenecker Aline , Cvengroš Ján , Aardoom Raphael , Togni Antonio
Published: November 2010

Diastereoselective ortho‐hydroxymethylation of (R)‐(1‐ferrocenylethyl)dimethylamine and Brønsted‐acid‐mediatednucleophilic substitution with phenyl(trifluoromethyl)phosphane affords an epimeric mixture of P‐stereogenic amine–phosphanes 4a and 4b, which are readily separated by crystallization from methanol. Subsequent substitution of the dimethylamino group with diphenylphosphane occurs without epimerization, yielding novel bis(phosphanes) 1a and 1b. These bis(phosphanes) combine three elements of chirality (C‐central, P‐central and planar) and bear a trifluoromethyl group at a stereogenic phosphorus atom. Their complexes with transition metals (Pd, Rh, Ir) were studied and characterized by means of NMR techniques and X‐ray crystallographic analyses, and the bidentate ligands proved efficient in stereoselective catalysis.
Sn/Li Exchange Reactions in 1,ω‐Distannylated Conjugated Trienes and Tetraenes: An Enabling Step for Polyene Synthesis
Authors: Burghart Jochen , Brückner Reinhard
Published: November 2010

Successive treatments of (1E,3E,5E)‐ or (1E,3Z,5E)‐1,6‐bis(tributylstannyl)hexa‐1,3,5‐triene with nBuLi and butanal rendered polyenyl alcohols resulting from one Sn/Li exchange reaction and exhibiting complete retention of the configuration of all C=C bonds. Mono‐ or dimethylated all‐E‐configured 1,6‐distannylated conjugated trienes as well as all‐E‐1,8‐bis(tributylstannyl)octa‐1,3,5,7‐tetraene and dimethylated congeners thereof reacted similarly. The respective Sn/Li exchange reactions affected the substructure Bu3Sn–CH=CH with a 93–94:7–6 preference over Bu3Sn–CMe=CH and with a 90:10 preference over Bu3Sn–CH=CMe. all‐E‐1‐Lithio‐6‐(tributylstannyl)hexa‐1,3,5‐triene was incorporated into navenone B after Negishi coupling and into (–)‐cicutoxin after acylation. NMR spectroscopy of our navenone B specimen revealed that certain resonances were misassigned previously.
An activated catalyst RhH(PPh3)4‐dppe‐ Me2S2 for α‐methylthiolaton of α‐phenyl ketones
Authors: Arisawa Mieko , Toriyama Fumihiko , Yamaguchi Masahiko
Published: November 2010

In the presence of catalytic amounts of RhH(PPh3)4, 1,2‐bis(diphenylphosphino)ethane (dppe), and dimethyl disulfide, cyclic and acyclic α‐phenyl ketones reacted with p‐cyano‐α‐methylthioa‐ cetophenone giving α‐methylthio‐α‐phenylketones. The activated catalyst containing dimethyl disulfide was effective for the α‐methylthiolation reaction of these less reactive substrates. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 22:18–23, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20650