bluuebunny/crossref_metadata_2025 huggingface dataset:
Regioselective Synthesis of Indoles via Rhodium‐Catalyzed CH Activation Directed by an In‐Situ Generated Redox‐Neutral Group
Authors: Muralirajan Krishnamoorthy , Cheng Chien‐Hong
Published: May 2014

A regioselective synthesis of indoles from arylhydrazine hydrochlorides with alkynes and diethyl ketone catalyzed by a rhodium complex is described. A possible mechanism involving an in‐situ generated oxidizing directing group NNCR1R2 assisted ortho‐CH activation and reductive elimination are proposed. The catalytic reaction is highly compatible with a wide range of functional arylhydrazines and alkynes. The reaction proceeds under mild reaction conditions and is atom‐step economical.

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Optimum Carrier Concentration in n‐Type PbTe Thermoelectrics
Authors: Pei Yanzhong , Gibbs Zachary M. , Gloskovskii Andrei , Balke Benjamin , Zeier Wolfgang G. , Snyder G. Jeffrey
Published: May 2014

Taking La‐ and I‐doped PbTe as an example, the current work shows the effects of optimizing the thermoelectric figure of merit, zT, by controlling the doping level. The high doping effectiveness allows the carrier concentration to be precisely designed and prepared to control the Fermi level. In addition to the Fermi energy tuning, La‐doping modifies the conduction band, leading to an increase in the density of states effective mass that is confirmed by transport, infrared reflectance and hard X‐ray photoelectron spectroscopy measurements. Taking such a band structure modification effect into account, the electrical transport properties can then be well‐described by a self‐consistent single non‐parabolic Kane band model that yields an approximate (m*T)1.5 dependence of the optimal carrier concentration for a peak power factor in both doping cases. Such a simple temperature dependence also provides an effective approximation of carrier concentration for a peak zT and helps to explain, the effects of other strategies such as lowering the lattice thermal conductivity by nanostructuring or alloying in n‐PbTe, which demonstrates a practical guide for fully optimizing thermoelectric materials in the entire temperature range. The principles used here should be equally applicable to other thermoelectric materials.
Synthese, Struktur und Anwendungen von Pyridiniumphosphanen
Authors: Tinnermann Hendrik , Wille Christian , Alcarazo Manuel
Published: May 2014

Neue kationische Liganden, die N‐Alkyl/Aryl‐Pyridiniumphosphane, wurden über eine kurze und skalierbare Syntheseroute hergestellt. Die Auswertung der elektronischen Eigenschaften dieser Phosphane zeigte schwaches σ‐Donor‐ und starkes π‐Akzeptorverhalten. Als Hilfsliganden eingesetzt, steigern diese Phosphane die π‐Azidität der entsprechenden PtII‐ und AuI‐Komplexe. Durch die erhöhte π‐Azidität sind die Metallkomplexe dieser Liganden in der Lage, die Aktivität von Alkinen gegenüber nukleophilen Angriffen wesentlich zu erhöhen. Die durch das Ligandendesign erhöhte Reaktivität wird anhand einiger mechanistisch verschiedener Platin(II)‐ und Gold(I)‐katalysierter Reaktionen aufgezeigt.
Synthesis, Structure, and Applications of Pyridiniophosphines
Authors: Tinnermann Hendrik , Wille Christian , Alcarazo Manuel
Published: May 2014

A new family of cationic ligands, N‐alkyl/aryl pyridiniophosphines, has been synthesized through a short, scalable, and highly modular route. Evaluation of their electronic properties evidenced weak σ‐donor and quite strong π‐acceptor character when used as ancillary ligands. These attributes confer a substantially enhanced π‐acidity to the PtII and AuI complexes thereof derived and, as result, they depict an improved ability to activate alkynes towards nucleophilic attack. This superior performance has been demonstrated along several mechanistically diverse PtII‐ and AuI‐catalyzed transformations.
Economic pre‐feasibility study for physical conversion of polyethylene terephthalate wastes to activated carbon
Authors: Torrik Ebrahim , Nejati Ehsan , Soleimani Mansooreh
Published: May 2014

Beneficial use of waste polymers is an important issue for environmental protection researchers. In this study, a brief summary has been presented for recycling methods of polyethylene terephthalate (PET) wastes. An economic pre‐feasibility study has been performed for the production of activated carbon from PET wastes. The proposed plant was used the physical activation process for the production of 10 000 t of activated carbon per year. The mass and energy balances and equipment designs of the process were performed using Aspen Plus 7.2 software. Asian countries have been selected as the location of this plant. The economic analysis of this plant for 2013 indicated that total capital investment and total production cost of plant were about $13 004 232 and $12 819 125, respectively. Using the economic criteria, the feasibility study of the project was conducted, and it was revealed that for a sale price of $1.7 per kg, minimum values of net present value ($418 486) and internal rate of return (15.33%) and the maximum value for payout period (25.44 years) have been reached. As it was expected, both net present value and internal rate of return increase by increasing sale price, while payout period decreases. This sensitivity analysis indicated that interest rate is the most effective parameter on net present value in each of the sale prices. © 2014 Curtin University of Technology and John Wiley & Sons, Ltd.
Aging behavior and mechanism of bio‐based engineering polyester elastomer nanocomposites
Authors: Fang Bowen , Kang Hailan , Wang Runguo , Wang Zhao , Wang Wencai , Zhang Liqun
Published: May 2014

Bio‐based elastomers used in industry have attracted much attention. We prepared bio‐based engineering polyester elastomer (BEE) nanocomposites by mixing bio‐based engineering polyester elastomers with carbon (CB). The CB/BEE nanocomposites were exposed to an artificial weathering environment for different time periods. Both its aging behavior changes and aging mechanism were investigated in this article. The tensile strength retention rates were each above 90% after aging at 100°C and 125°C for 72 h. CB/BEE nanocomposites exhibited good anti‐aging properties. Furthermore, the chemical changes were detected by Fourier transform infrared spectroscopy and differential scanning calorimetry. The crosslink density changes during aging of BEE were determined as well. A plausible aging mechanism of BEE was proposed. It can be concluded that the thermal oxidation process gives priority to further crosslinking in the initial period of aging. As the aging time increases, chain scission becomes the dominant element in the subsequent thermal oxidation process. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40862.
Surface selectivity competition of newly synthesized polyarylidene(keto amine) polymers toward different metal ions
Authors: Hussein Mahmoud A. , Marwani Hadi M. , Alamry Khalid A. , Asiri Abdullah M. , El‐Daly Samy A.
Published: May 2014

A new series of polyarylidene(keto amine)s (PAKAs) 3a−3e based on thiophene moieties in polymer main chains were synthesized with the solution polycondensation technique. The polymers were synthesized by the reaction of the new monomer 1,1′‐(1E,1′E)‐(2‐oxocyclohexane‐1,3‐diylidene)bis(methanylylidene)bis(thiophene‐5,2‐diyl)bis(2‐chloroethanone) (2) with different diamines. The new monomer was first synthesized under the normal conditions of the Friedel–Crafts reaction. The results obtained from both elemental and spectral analyses were consistent with the chemical structure of the new monomers and the polymers. Moreover, the identification of the polymers was carried out with different characterization techniques. The analytical competition of the newly synthesized PAKA polymers as selected examples (3d and 3e) was also evaluated for a selective extraction of metal ions, including Cd(II), Co(II), Cu(II), Cr(III), Fe(III), Ni(II), and Zn(II), before their determination by inductively coupled plasma–optical emission spectrometry. The results of the selectivity study demonstrated that the 3d and 3e polymers was the most selective toward Co(II) and Fe(III), respectively. However, the adsorption capacity of 3d for Co(II) was improved by 10.10% in comparison to that of 3e for Fe(III) after only 1 h of contact time. Moreover, the adsorption isotherm data also showed that the adsorption process was mainly monolayer on the homogeneous adsorbent surfaces of both polymers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40873.
Developing toughened aromatic polybenzoxazines using thermoplastic oligomers and telechelics, part 1: Preparation and characterization of the functionalized oligomers
Authors: Hamerton Ian , McNamara Lisa T. , Howlin Brendan J. , Smith Paul A. , Cross Paul , Ward Steven
Published: May 2014

The preparation and characterization of three families of thermoplastic oligomers (Mn = 2918–13263 g mol−1) based on polyarylsulfone (PSU) differing in both molecular weight and terminal functionality and one series of polyarylethersulfone (PES) of different molecular weights is reported. Infrared and nuclear magnetic resonance spectroscopy data support the formation of both the hydroxyl terminated oligomers and conversion (67–89% depending on molecular weight) to the telechelic PSU oligomer bearing reactive benzoxazine groups. Differential scanning calorimetry reveals that the onset of homopolymerization in the telechelic PSU oligomer occurs at around 100°C (peak maximum 125°C at 10 K/min) and rescans show values of the glass transition (for the homopolymers) ranging from 124 to 167°C depending on molecular weight. The influence on the oligomer backbone and terminal functionality is examined using thermal analysis. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40875.
Enhancing rheological properties of hydrophobically associative polyacrylamide aqueous solutions by hybriding with silica nanoparticles
Authors: Zhu Dingwei , Han Yugui , Zhang Jichao , Li Xiaolan , Feng Yujun
Published: May 2014

Organic/inorganic hybrid aqueous solutions were prepared by mixing silica nanoparticle suspension and hydrophobically associating polyacrylamide (HAPAM) solution, and their rheological behaviors were examined in both pure water and brine in comparison with HAPAM. It was found that HAPAM/silica hybrid exhibits viscosity enhancement in aqueous solution and better heat‐ and salt‐ tolerances than HAPAM. Meanwhile, their long‐term thermal stability is also improved. Cryo‐TEM observation reveals that a reinforced three‐dimensional network structure of HAPAM/silica hybrid is formed. These improved properties are attributed to the formed hydrogen bond between carbonyl groups in HAPAM skeleton and silanol functionalities in silica nanoparticles in the hybrid system, and the silica nanoparticles in the hybrid act as physical crosslinkers between macromolecules. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40876.
Morphological and local mechanical surface characterization of ballistic fibers via AFM
Authors: Strawhecker Kenneth E. , Cole Daniel P.
Published: May 2014

As‐received morphologies, defect structures, and contact moduli of Kevlar KM2 Plus and three other ballistic fibers varying in chemistry and processing, were observed and compared using atomic force microscopy (AFM) and instrumented nanoindentation (NI) techniques. Surface features and defects were defined and measured for each fiber chemistry: p‐phenylene terephthalamides (PPTA including KM2 Plus and Twaron), co‐polymer aramid (AuTx), and ultra high molecular weight polyethylene (UHMWPE including Dyneema). Although a multitude of surface defects were observed in each fiber, the types of defects were similar from one fiber type to another. It was found that surface defects generally map to a more compliant local modulus value. Contact modulus values were compared with NI elastic modulus values to demonstrate validity for the AFM technique. Challenges and limitations of the AFM technique for cataloging defects are discussed. This study is the first which attempts to outline the various morphologies found on several fiber surfaces. These local property studies will enable future comparisons with single filament and bulk fiber properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40880.
Adhesion between polymer surface modified by graft polymerization and tissue during surgery using an ultrasonically activated scalpel device
Authors: Nam Kwangwoo , Iwata Takuya , Kimura Tsuyoshi , Ikake Hiroki , Shimizu Shigeru , Masuzawa Toru , Kishida Akio
Published: May 2014

In the field of surgery, achieving adhesion between a polymer implant and tissue poses a challenge considering that suturing is not appropriate for the stability of such implants. An ultrasonically activated scalpel that generates heat by mechanical vibration and promotes adhesion between a polymer implant and native tissue by pressing the two materials together has very good potential for application in the field. To determine the type of polymer that is suitable for the purpose, we investigated polyethylene (PE) and polystyrene (PS) films, the surfaces of which were activated by corona discharge. Graft polymerization was then performed on the corona‐treated surfaces to vary their properties. The corona‐treated PE and PS films grafted with poly(acrylic acid), poly(methacrylic acid), poly(vinyl benzylacrylic acid), and poly(hydroxylethyl acrylate), respectively, adhered to the tissue when the ultrasonically activated scalpel was applied. The heat generated by the mechanical vibration and the applied pressure enabled the carboxyl or hydroxyl groups to bond with the proteins in the extracellular matrix. We therefore concluded that it was possible to integrate this technique in the development of new types of polymer devices that could be stably implanted in a living body. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40885.
A life cycle model of XML documents
Authors: Salminen Airi , Jauhiainen Eliisa , Nurmeksela Reija
Published: May 2014

Electronic documents produced in business processes are valuable information resources for organizations. In many cases they have to be accessible long after the life of the business processes or information systems in connection with which they were created. To improve the management and preservation of documents, organizations are deploying Extensible Markup Language (XML) as a standardized format for documents. The goal of this paper is to increase understanding of XML document management and provide a framework to enable the analysis and description of the management of XML documents throughout their life. We followed the design science approach. We introduce a document life cycle model consisting of five phases. For each of the phases we describe the typical activities related to the management of XML documents. Furthermore, we also identify the typical actors, systems, and types of content items associated with the activities of the phases. We demonstrate the use of the model in two case studies: one concerning the State Budget Proposal of the Finnish government and the other concerning a faculty council meeting agenda at a university.
Engaging and maintaining a sense of being informed: Understanding the tasks motivating twitter search
Authors: Elsweiler David , Harvey Morgan
Published: May 2014

Micro‐blogging services such as Twitter represent constantly evolving, user‐generated sources of information. Previous studies show that users search such content regularly but are often dissatisfied with current search facilities. We argue that an enhanced understanding of the motivations for search would aid the design of improved search systems, better reflecting what people need. Building on previous research, we present qualitative analyses of two sources of data regarding how and why people search Twitter. The first, a diary study (p = 68), provides descriptions of Twitter information needs (n = 117) and important meta‐data from active study participants. The second data set was established by collecting first‐person descriptions of search behavior (n = 388) tweeted by twitter users themselves (p = 381) and complements the first data set by providing similar descriptions from a more plentiful source. The results of our analyses reveal numerous characteristics of Twitter search that differentiate it from more commonly studied search domains, such as web search. The findings also shed light on some of the difficulties users encounter. By highlighting examples that go beyond those previously published, this article adds to the understanding of how and why people search such content. Based on these new insights, we conclude with a discussion of possible design implications for search systems that index micro‐blogging content.
Target‐Triggered NIR Emission with a Large Stokes Shift for the Detection and Imaging of Cysteine in Living Cells
Authors: Zhao Chunchang , Li Xiuai , Wang Feiyi
Published: May 2014

Background autofluorescence from biological systems generally reduces the sensitivity of a fluorescent probe for imaging biological targets. Addressing this challenge requires the development of fluorescent probes that produce emission in the near‐infrared region. Herein, we report the design and synthesis of a fluorescent probe that generates an NIR emission with a large Stokes shift upon the selective response to Cys over Hcy and GSH. The probe is designed to consist of two Cys‐sensing sites, an acrylate ester and an aldehyde installed ortho to each other. The reaction of the probe with Cys triggers an excited state intramolecular proton transfer process upon photo‐excitation, thereby producing an NIR emission with a large Stokes shift. Accordingly, this probe hold great promise for the selective detection of Cys in biological systems. We further demonstrate the capacity of this probe for Cys imaging in living cells.
On‐line Parameter Estimation via Algebraic Method: An Experimental Illustration
Authors: Delpoux R. , Floquet T.
Published: May 2014

This article presents an algebraic online parameters estimation method for linear time invariant (LTI) systems, subject to polynomial perturbations. Particular attention is given to practical implementation. The estimator may be expressed as a simple finite impluse response (FIR) filter, which is advantageous for online application, since the coefficients may be computed offline. The robustification against possible singularities is shown, the approach has the advantage to eliminate singularities that may occur in the experimental identification. This algorithm is illustrated experimentally on a permanent magnet stepper motor (PMSM) and a magnetic bearing for which parametric estimation is known to be a difficult task. The parameters to be estimated are sometimes measurable with difficulty and may vary slightly over time.
Flow injection determination of diclofenac sodium based on its sensitizing effect on the chemiluminescent reaction of acidic potassium permanganate–formaldehyde
Authors: Song Jingjing , Sun Pulv , Ji Zhongling , Li Jianguo
Published: May 2014

A sensitive and simple chemiluminescent (CL) method for the determination of diclofenac sodium has been developed by combining the flow injection technique and its sensitizing effect on the weak CL reaction between formaldehyde and acidic potassium permanganate. A calibration curve is constructed for diclofenac sodium under optimized experimental parameters over the range 0.040–5.0 µg/mL and the limit of detection is 0.020 µg/mL (3σ). The inter‐assay relative standard deviation for 0.040 µg/mL diclofenac sodium (n = 11) is 2.0%. This method is rapid, sensitive, simple, and shows good selectivity and reproducibility. The proposed method has been successfully applied to the determination of the studied diclofenac sodium in pharmaceutical preparations with satisfactory results. Furthermore, the possible mechanism for the CL reaction has been discussed in detail on the basis of UV and CL spectra. Copyright © 2014 John Wiley & Sons, Ltd.
Development of new antiatherosclerotic and antithrombotic drugs utilizing F11 receptor (F11R/JAM‐A) peptides
Authors: Babinska A. , Clement C. C. , Swiatkowska M. , Szymanski J. , Shon A. , Ehrlich Y. H. , Kornecki E. , Salifu M. O.
Published: May 2014

Peptides with enhanced resistance to proteolysis, based on the amino acid sequence of the F11 receptor molecule (F11R, aka JAM‐A/Junctional adhesion molecule‐A), were designed, prepared, and examined as potential candidates for the development of anti‐atherosclerotic and anti‐thrombotic therapeutic drugs. A sequence at the N‐terminal of F11R together with another sequence located in the first Ig‐loop of this protein, were identified to form a steric active‐site operating in the F11R‐dependent adhesion between cells that express F11R molecules on their external surface. In silico modeling of the complex between two polypeptide chains with the sequences positioned in the active‐site was used to generate peptide‐candidates designed to inhibit homophilic interactions between surface‐located F11R molecules. The two lead F11R peptides were modified with D‐Arg and D‐Lys at selective sites, for attaining higher stability to proteolysis in vivo. Using molecular docking experiments we tested different conformational states and the putative binding affinity between two selected D‐Arg and D‐Lys‐modified F11R peptides and the proposed binding pocket. The inhibitory effects of the F11R peptide 2HN‐(dK)‐SVT‐(dR)‐EDTGTYTC‐CONH2 on antibody‐induced platelet aggregation and on the adhesion of platelets to cytokine‐inflammed endothelial cells are reported in detail, and the results point out the significant potential utilization of F11R peptides for the prevention and treatment of atherosclerotic plaques and associated thrombotic events. © 2014 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 102: 322–334, 2014.
Highly sensitive LC‐MS/MS method for determination of galantamine in rat plasma: application to pharmacokinetic studies in rats
Authors: Suresh P. S. , Mullangi Ramesh , Sukumaran Sathesh Kumar
Published: May 2014

A rapid and highly sensitive assay method has been developed and validated for the estimation of galantamine (GLM) in rat plasma using liquid chromatography coupled to tandem mass spectrometry with electrospray ionization in the positive‐ion mode. The assay procedure involves a simple liquid–liquid extraction of GLM and phenacetin (internal standard, IS) from rat plasma using acetonitrile. Chromatographic separation was achieved with 0.2% formic acid:acetonitrile (50:50, v/v) at a flow rate of 0.60 mL/min on an Atlantis dC18 column with a total run time 2.5 min. The MS/MS ion transitions monitored were 288.10 → 213.10 for GLM and 180.10 → 110.10 for IS. Method validation was performed as per United States Food and Drug Administration guidelines and the results met the acceptance criteria. The lower limit of quantitation achieved was 0.12 ng/mL and linearity was observed from 0.12 to 525 ng/mL. The intra‐ and inter‐day precision were in the ranges of 4.73–11.7 and 5.83–8.64%, respectively. This novel method has been applied to a pharmacokinetic study in rats. Copyright © 2014 John Wiley & Sons, Ltd.
Distribution study of tryptanthrin in rat tissues by HPLC and its relationship with meridian tropism of indigo naturalis in traditional Chinese medicine
Authors: Zhang Ning , Hua Ying , Wang Cuiling , Sun Yanni , Wang Zheng , Liu Zhulan , Liu Jianli
Published: May 2014

The aim of the present study is to characterize the distribution of tryptanthrin (TRYP) in rat tissues following oral administration at a dose of 100 mg/kg and its relationship with meridian tropism (MT) of indigo naturalis (IN) in traditional Chinese medicine (TCM). For quantitative analysis in biological samples, a sensitive, inexpensive and accurate high‐performance liquid chromatographic method was developed and validated with 2‐hydroxy acetophenone as internal standard, a Shimadzu C18 column and water–acetonitrile (55:45, v/v) as mobile phase. Acceptable intra‐day and inter‐day precision at high, medium and low concentration was acquired with RSD ranging from 0.87 to 5.22% and from 1.25 to 6.47%, respectively. Good assay and extraction recoveries were obtained with a single and relatively fast step to precipitate protein. The extraction recovery of TRYP ranged from 87.5 to 94.5 %. TRYP concentration was highest in the liver and remained for a much longer time than in other tissues. It could also be detected in kidney, lung, heart and spleen, but not in brain under the experimental conditions. The results confirmed the traditional knowledge of TCM that MT of IN belongs to the liver meridians and demonstrated that TRYP is one of the active constituents of the MT of IN. Copyright © 2014 John Wiley & Sons, Ltd.
Microbial lipid production from pretreated and hydrolyzed corn fiber
Authors: Liang Yanna , Perez Ivan , Goetzelmann Kyle , Trupia Sabrina
Published: May 2014

With its high content of carbohydrates and low percentage of lignin, corn fiber represents a renewable feedstock that can be processed to produce biofuels. Through a combination of pretreatment by lime and enzymatic hydrolysis, total reducing sugars of 700 mg/g corn fiber were released. This amount is equivalent to 92.7% of theoretically available sugars in corn fiber. The resulting hydrolysate itself did not support any growth of Cryptococcus curvatus. But with addition of minerals, C. curvatus grew to a cell density of 6.6 g/L in 6 days. Using the adapted cells, rapid sugar consumption and cell growth were observed. This study demonstrated that it is feasible to produce microbial lipids from corn fiber through pretreatment, enzymatic hydrolysis, and fermentation. In addition, C. curvatus is an excellent candidate for this application since it can utilize all major sugars, glucose, xylose, and arabinose with yield of cells and lipids as 0.55 and 0.27 g/g sugars, respectively. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:945–951, 2014
High CD49f expression is associated with osteosarcoma tumor progression: a study using patient‐derived primary cell cultures
Authors: Penfornis Patrice , Cai David Z. , Harris Michael R. , Walker Ryan , Licini David , Fernandes Joseph D. A. , Orr Griffin , Koganti Tejaswi , Hicks Chindo , Induru Spandana , Meyer Mark S. , Khokha Rama , Barr Jennifer , Pochampally Radhika R.
Published: May 2014

Overall prognosis for osteosarcoma (OS) is poor despite aggressive treatment options. Limited access to primary tumors, technical challenges in processing OS tissues, and the lack of well‐characterized primary cell cultures has hindered our ability to fully understand the properties of OS tumor initiation and progression. In this study, we have isolated and characterized cell cultures derived from four central high‐grade human OS samples. Furthermore, we used the cell cultures to study the role of CD49f in OS progression. Recent studies have implicated CD49f in stemness and multipotency of both cancer stem cells and mesenchymal stem cells. Therefore, we investigated the role of CD49f in osteosarcomagenesis. First, single cell suspensions of tumor biopsies were subcultured and characterized for cell surface marker expression. Next, we characterized the growth and differentiation properties, sensitivity to chemotherapy drugs, and anchorage‐independent growth. Xenograft assays showed that cell populations expressing CD49fhi/CD90lo cell phenotype produced an aggressive tumor. Multiple lines of evidence demonstrated that inhibiting CD49f decreased the tumor‐forming ability. Furthermore, the CD49fhi/CD90lo cell population is generating more aggressive OS tumor growth and indicating this cell surface marker could be a potential candidate for the isolation of an aggressive cell type in OSs.
Tumor necrosis factor‐α regulates matrix metalloproteinase‐2 expression and cell migration via ERK pathway in rat glomerular mesangial cells
Authors: Wang Yuebing , Li Ming , Xu Yang , He Ningning , Leng Liang , Li Zongjin
Published: May 2014

Mesangial cells (MCs), vascular smooth muscle‐derived cells, contribute to glomerular injury by generating a number of cytokines such as tumor necrosis factor‐α (TNF‐α). Matrix metalloproteinases (MMPs), regulated by various stimuli, are important in remodeling of glomerular ECM, which leads to a number of renal diseases. We investigated whether TNF‐α participated in the regulation of MMPs and explored signal pathways involved in TNF‐α‐induced MMPs expression in rat glomerular MCs. Western blot and RT‐qPCR results showed that treatment with TNF‐α significantly increased the expression of MMP‐2, but not MMP‐9 at both protein and mRNA levels in rat glomerular MCs. The extracellular signal‐regulated kinase (ERK) and nuclear factor‐kappaB (NF‐κB) signal pathways were activated by TNF‐α. Moreover, the activation of NF‐κB pathway in rat MCs was effectively inhibited by PD98059, specific inhibitor of ERK, suggesting a role for ERK in regulating NF‐κB function. PD98059 or NF‐κB signal pathway selective inhibitor Bay 11‐7082 effectively blocked TNF‐α‐induced expression of MMP‐2 in rat MCs, as determined by gene and protein expression. C‐jun N‐terminal kinase (JNK) signal pathway had no effect on TNF‐α‐induced expression of MMP‐2, even though it was also activated by TNF‐α in rat MCs. Furthermore, TNF‐α could induce the cell migration of rat MCs, whereas ERK signal pathway specific inhibitor PD98059 compromised the cell migration triggered by TNF‐α. Thus, TNF‐α upregulates the expression of MMP‐2 via activation of ERK‐dependent NF‐κB pathway in rat MCs, which may contribute to the cell migration of rat MCs.
Comparative study of directional differentiation of human and mouse embryonic stem cells into cardiomyocytes
Authors: Mu Junsheng , Li Xianshuai , Yuan Shumin , Zhang Jianqun , Bo Ping
Published: May 2014

This comparative study investigates the method, efficiency, and anti‐hypoxic ability of cardiomyocytes, directionally induced from human (h) and mouse (m) embryonic stem cells (ESCs). hESCs were induced into cardiomyocytes by suspension culture, without inducers, or adherent culture using the inducers activin A and BMP4. mESCs were induced into cardiomyocytes by hanging‐drop method, without inducers or induced with vitamin C. All four methods successfully induced ESCs to differentiate into cardiomyocytes. There was a significant difference between groups with and without inducers. A significant difference was found between mESC and hESC groups with inducers. The average beating frequency of cardiomyocytes differentiated from hESC was lower than cardiomyocytes differentiated from mESC, while the average beating frequency of cardiomyocytes differentiated from the same cell line, despite different culture methods, did not differ. Beating cardiomyocytes of each group were positive for cTnT staining. Spontaneous action potentials of beating cardiomyocytes were detected by patch‐clamp experiments in each group. Different apoptotic ratios were detected in beating cardiomyocytes in each group and the difference between cardiomyocytes induced from mESCs and hESCs was statistically significant. The differentiation efficiencies in the groups without inducers were significantly higher than those without inducers. The induction of mESCs was more simple and efficient compared with hESCs. Without the presence of other protective factors, the anti‐hypoxic ability of cardiomyocytes induced from hESCs was stronger and the beating times were longer in vitro compared with mESCs.
Measuring mechanical properties in cells: three easy methods for biologists
Authors: Bonakdar Navid , Schilling Achim , Lennert Pablo , Spörrer Marina , Gerum Richard C. , Alonso José Luis , Goldmann Wolfgang H.
Published: May 2014

The mechanism by which cells sense stresses and transmit them throughout the cytoplasm and the cytoskeleton (CSK) and by which these mechanical signals are converted into biochemical signaling responses is not clear. Specifically, there is little direct experimental evidence on how intracellular CSK structural elements in living cells deform and transmit stresses in response to external mechanical forces. Existing theories have invoked various biophysical and biochemical mechanisms to explain how cells spread, deform, divide, move, and change shape in response to mechanical inputs, but rigorous tests in cells are lacking. The lack of data and understanding is preventing the identification of mechanisms and sites of mechano‐regulation in cells. Here, we introduce and describe three unique and easy methods for biologists to determine mechanical properties and signaling events in cells.
Stimulatory effect of HGF‐overexpressing adipose tissue‐derived mesenchymal stem cells on thymus regeneration in a rat thymus involution model
Authors: Jung Woo‐Sung , Han Sei‐Myoung , Kim Sung‐Min , Kim Mi‐Eun , Lee Jun‐Sik , Seo Kyoung‐Won , Youn Hwa‐Young , Lee Hee‐Woo
Published: May 2014

The thymus is the central lymphoid organ providing a unique and essential microenvironment for T‐cell precursor development into mature functionally competent T‐lymphocytes. Thus, it is important to develop the strategies for enhancing thymic regeneration from involution induced by a variety of clinical treatments and conditions. Hepatocyte growth factor (HGF) promotes proliferation in a variety of cell types. We have used stem cell‐based HGF gene therapy to enhance regeneration from acute thymic involution. HGF‐overexpressing human adipose tissue‐derived mesenchymal stem cells (HGF‐hATMSCs) were generated by liposomal transfection with the pMEX expression vector, constructed by inserting the HGF gene. Significantly increased HGF expression in these cells was confirmed by reverse transcription‐polymerase chain reaction and an enzyme‐linked immunosorbent assay. HGF produced by HGF‐hATMSCs enhanced the proliferation of a mouse thymic epithelial cell line and the expression of interleukin‐7 in vitro. We also examined the effect of HGF‐hATMSCs on thymic regeneration in rats with acute thymic involution. Significant increases in thymus size and weight, as well as the number of thymocytes (especially, early thymocyte progenitors), were seen in the HGF‐hATMSCs‐treated rats compared to saline‐treated control animals. A stimulatory effect of HGF‐hATMSCs on thymic regeneration has therefore been shown, highlighting the clinical value of HGF‐hATMSCs for treating thymic involution.
Tight and Selective Caging of Chloride Ions by a Pseudopeptidic Host
Authors: Martí Inés , Bolte Michael , Burguete M. Isabel , Vicent Cristian , Alfonso Ignacio , Luis Santiago V.
Published: May 2014

The selective molecular recognition of chloride versus similar anions is a continuous challenge in supramolecular chemistry. We have designed and prepared a simple pseudopeptidic cage (1 a) that defines a cavity suitable for the tight encapsulation of chloride. The interaction of the protonated form of 1 a with different inorganic anions was studied in solution by 1H NMR spectroscopy and ESI‐MS, and in the solid state by X‐ray diffraction. The solution binding data showed that the association constants of 1 a to chloride are more than two orders of magnitude higher than to any other tested inorganic anion. Remarkably, 1 a displayed a high selectivity for chloride over other closely related halides such as bromide (selectivity=111), iodide (selectivity=719), and fluoride (selectivity >1000). Binding experiments (1H NMR spectroscopy and ESI‐MS) suggested that 1 a has a high‐affinity (inner) binding site and an additional low‐affinity (external) binding site. The supramolecular complexes with F−, Cl−, and Br− have been also characterized by the X‐ray diffraction of the corresponding [1 a⋅nHX] crystalline salts. The structural data show that the chloride anion is tightly encapsulated within the host, in a binding site defined by a very symmetric array of electrostatic H‐bonds. For the fluoride salt, the size of the cage cavity is too large and is occupied by a water molecule, which fits inside the cage efficiently competing with F−. In the case of the bigger bromide, the mismatch of the anion inside the cage caused a geometrical distortion of the host and thus a large energetic penalty for the interaction. This minimalistic pseudopeptidic host represents a unique example of the construction of a simple well‐defined binding pocket that allows the highly selective molecular recognition of a challenging substrate.
New Polydentate Trimethylsilyl Chalcogenide Reagents for the Assembly of Polyferrocenyl Architectures
Authors: Fard Mahmood Azizpoor , Khalili Najafabadi Bahareh , Hesari Mahdi , Workentin Mark S. , Corrigan John F.
Published: May 2014

A series of polychalcogenotrimethylsilane complexes Ar(CH2ESiMe3)n, (Ar=aryl; E=S, Se; n=2, 3, and 4) can be prepared from the corresponding polyorganobromide and M[ESiMe3] (M=Na, Li). These represent the first examples of the incorporation of such a large number of reactive ESiMe3 moieties onto an organic molecular framework. They are shown to be convenient reagents for the preparation of the polyferrocenylseleno‐ and thioesters from ferrocenoyl chloride. The synthesis, structures, and spectroscopic properties of the new silyl chalcogen complexes 1,4‐(Me3SiECH2)2(C6Me4) (E=S, 1; E=Se, 2), 1,3,5‐(Me3SiECH2)3(C6Me3) (E=S, 3; E=Se, 4) and 1,2,4,5‐(Me3SiECH2)4(C6H2) (E=S, 5; E=Se, 6) and the polyferrocenyl chalcogenoesters [1,4‐{FcC(O)ECH2}2(C6Me4)] (E=S, 7; E=Se, 8), [1,3,5‐{FcC(O)ECH2}3(C6Me3)] (E=S, 9; E=Se, 10) and [1,2,4,5‐{FcC(O)ECH2}4(C6H2)] (E=S, 11 illustrated; E=Se, 12) are reported. The new polysilylated reagents and polyferrocenyl chalcogenoesters have been characterized by multinuclear NMR spectroscopy (1H, 13C, 77Se), electrospray ionization mass spectrometry and, for complexes 1, 2, 3, 4, 7, 8, and 11, single‐crystal X‐ray diffraction. The cyclic voltammograms of complexes 7–11 are presented.
An Investigation of Photo‐ and Pressure‐Induced Effects in a Pair of Isostructural Two‐Dimensional Spin‐Crossover Framework Materials
Authors: Sciortino Natasha F. , Neville Suzanne M. , Desplanches Cédric , Létard Jean‐François , Martinez Victor , Real José Antonio , Moubaraki Boujemaa , Murray Keith S. , Kepert Cameron J.
Published: May 2014

Two new isostructural iron(II) spin‐crossover (SCO) framework (SCOF) materials of the type [Fe(dpms)2(NCX)2] (dpms=4,4′‐dipyridylmethyl sulfide; X=S (SCOF‐6(S)), X=Se (SCOF‐6(Se))) have been synthesized. The 2D framework materials consist of undulating and interpenetrated rhomboid (4,4) nets. SCOF‐6(S) displays an incomplete SCO transition with only approximately 30 % conversion of high‐spin (HS) to low‐spin iron(II) sites over the temperature range 300–4 K (T1/2=75 K). In contrast, the NCSe− analogue, SCOF‐6(Se), displays a complete SCO transition (T1/2=135 K). Photomagnetic characterizations reveal quantitative light‐ induced excited spin‐state trapping (LIESST) of metastable HS iron(II) sites at 10 K. The temperature at which the photoinduced stored information is erased is 58 and 50 K for SCOF‐6(S) and SCOF‐6(Se), respectively. Variable‐pressure magnetic measurements were performed on SCOF‐6(S), revealing that with increasing pressure both the T1/2 value and the extent of spin conversion are increased; with pressures exceeding 5.2 kbar a complete thermal transition is achieved. This study confirms that kinetic trapping effects are responsible for hindering a complete thermally induced spin transition in SCOF‐6(S) at ambient pressure due to an interplay between close T1/2 and T(LIESST) values.
Facile Preparation of Core–Shell Magnetic Metal–Organic Framework Nanospheres for the Selective Enrichment of Endogenous Peptides
Authors: Xiong Zhichao , Ji Yongsheng , Fang Chunli , Zhang Quanqing , Zhang Lingyi , Ye Mingliang , Zhang Weibing , Zou Hanfa
Published: May 2014

Facile preparation of core–shell magnetic metal–organic framework nanospheres by a layer‐by‐layer approach is presented. The nanospheres have high surface area (285.89 cm2 g−1), large pore volume (0.18 cm3 g−1), two kinds of mesopores (2.50 and 4.72 nm), excellent magnetic responsivity (55.65 emu g−1), structural stability, and good dispersibility. The combination of porosity, hydrophobicity, and uniform magnetism was exploited for effective enrichment of peptides with simultaneous exclusion of high molecular weight proteins. The nanospheres were successfully applied in the selective enrichment of endogenous peptides in human serum.
A SIM‐MOF: Three‐Dimensional Organisation of Single‐Ion Magnets with Anion‐Exchange Capabilities
Authors: Baldoví José J. , Coronado Eugenio , Gaita‐Ariño Alejandro , Gamer Christoph , Giménez‐Marqués Mónica , Mínguez Espallargas Guillermo
Published: May 2014

The formation of a metal–organic framework (MOF) with nodes that have single‐molecule magnet (SMM) behaviour has been achieved by using mononuclear lanthanoid analogues, also known as single‐ion magnets (SIMs), which enormously simplifies the challenging issue of making SMM‐MOFs. Here we present a rational design of a family of MOFs, [Ln(bipyNO)4](TfO)3⋅x solvent (Ln=Tb (1); Dy (2); Ho (3); Er (4); TfO=triflate), in which the lanthanoid centres have an square‐antiprismatic coordination environment suitable for SIM behaviour. Magnetic measurements confirm the existence of slow magnetic relaxation typical of SMMs, which has been rationalised by means of a radial effective charge model. In addition, we have explored the incorporation of bulky polyoxometalates (POMs) into the cavities of the SIM‐MOF by anion exchange, finding that they do not interfere with the slow magnetic relaxation. This demonstrates the robustness of the frameworks and opens the possibility of incorporating non‐innocent anions.
Facile Synthesis of Dibenzopentalene Dianions and Their Application as New π‐Extended Ligands
Authors: Kuwabara Takuya , Ishimura Kazuya , Sasamori Takahiro , Tokitoh Norihiro , Saito Masaichi
Published: May 2014

Reduction of phenyl(silyl)ethynes with potassium followed by quenching with iodine gave dibenzopentalenes in moderate yields. The intermediates of the reactions, dipotassium dibenzopentalenides, were isolated. The first dibenzopentalene–transition‐metal complex was successfully synthesized. The ruthenium atoms are located above the six‐membered rings. However, X‐ray diffraction analysis and theoretical calculations revealed that the aromatic nature of the five‐membered rings was retained. The cyclic voltammetry of the Ru complex revealed two oxidation waves with relatively large separation.
Counterions Control Whether Self‐Assembly Leads to Formation of Stable and Well‐Defined Unilamellar Nanotubes or Nanoribbons and Nanorods
Authors: Shi Dong , Schwall Christian , Sfintes George , Thyrhaug Erling , Hammershøj Peter , Cárdenas Marite , Simonsen Jens B. , Laursen Bo W.
Published: May 2014

Self‐assembly of the amphiphilic π‐conjugated carbenium ion ATOTA‐1+ in aqueous solution selectively leads to discrete and highly stable nanotubes or nanoribbons and nanorods, depending on the nature of the counterion (Cl− vs. PF6−, respectively). The nanotubes formed by the Cl− salt illustrate an exceptional example of a structural well‐defined (29±2 nm in outer diameter) unilamellar tubular morphology featuring π‐conjugated functionality and high stability and flexibility, in aqueous solution.
Association Between N‐Terminal Pro‐Brain Natriuretic Peptide Levels and Contrast‐Induced Nephropathy in Patients Undergoing Percutaneous Coronary Intervention for Acute Coronary Syndrome
Authors: Kurtul Alparslan , Duran Mustafa , Yarlioglues Mikail , Murat Sani Namik , Demircelik Muhammed Bora , Ergun Gokhan , Acikgoz Sadik Kadri , Sensoy Baris , Cetin Mustafa , Ornek Ender
Published: May 2014

Background

Contrast‐induced nephropathy (CIN) is associated with significantly increased morbidity and mortality after percutaneous coronary intervention (PCI). Patients with acute coronary syndrome (ACS) are at higher risk for CIN. N‐terminal pro‐brain natriuretic peptide (NT‐proBNP) is closely linked to the prognosis as a strong predictor of both short‐ and long‐term mortality in patients with ACS.

Hypothesis

We hypothesized that NT‐proBNP levels on admission can predict the development of CIN after PCI for ACS.

Methods

A total of 436 patients (age 62.27 ± 13.01 years; 64.2% male) with ACS undergoing PCI enrolled in this study. Admission NT‐proBNP levels were measured before PCI. Serum creatinine values were measured before and within 72 hours after the administration of contrast agents. Patients were divided into 2 groups: CIN group and no‐CIN group. CIN was defined as an increase in serum creatinine level of ≥0.5 mg/dL or ≥25% above baseline within 72 hours after contrast administration.

Results

CIN developed in 63 patients (14.4%). Baseline NT‐proBNP levels were significantly higher in patients who developed CIN compared to those who did not develop CIN (median 774 pg/mL, interquartile range 177.4–2184 vs median 5159 pg/mL, interquartile range 2282–9677, respectively; P < 0.001). Multivariate analysis found that NT‐proBNP (odds ratio [OR]: 3.448, 95% confidence interval [CI]: 1.394‐8.474, P = 0.007) and baseline creatinine (OR: 6.052, 95% CI: 1.860‐19.686, P = 0.003) were independent predictors of CIN.

Conclusions

Admission NT‐proBNP level is an independent predictor of the development of CIN after PCI in ACS.
The Growth and Establishment of Floating Turions of Potamogeton crispus Are Not Favored by Summer Climate
Authors: Xie Dong , Zhou Hengjie , Ji Haiting , An Shuqing
Published: May 2014

The dispersion of asexual propagules is an important determinant for the spread and establishment of many aquatic plant species. In order to improve the understanding of the expansion of the Potamogeton crispus population, an in situ growth experiment with P. crispus turions was performed in a 30 days period. The sinking turions produced longer seedlings and more leaves than that of floating turions during the experimental period. A lower dark respiration rate and higher activities of superoxide dismutase and peroxidase were detected in the floating turions than those in the sinking turions, indicating that the self‐protection process of the floating turions and stress condition (high sunlight exposure and temperature) in summer may influence the primary metabolites of these floating turions. Moreover, we also found that the scale leaf porosities of the floating turions would determine the buoyancy of turions. These results indicated that the sinking and floating of P. crispus turions are determined by the anatomical structures and in situ summer climatic condition is unfavorable for the establishment of P. crispus floating turions.
Effects of Ammonia Nitrogen and Sediment Nutrient on Growth of the Submerged Plant Vallisneria natans
Authors: Zhu Zhengjie , Yuan Hezhong , Wei Ying , Li Pengshan , Zhang Peihua , Xie Dong
Published: May 2014

In order to investigate the impacts of ammonia nitrogen concentration and the necessity of dredging, five levels of ammonia nitrogen including 0, 2, 4, 8, and 16 mg L−1 and two levels of sediments nutriments (high and low) were treated. The total biomass, leaf, root, and flower biomasses were selected as the growth indicators, while total chlorophyll (i.e., chl‐a and ‐b), malondialdehyde (MDA), and free proline as subsidiary physiological index. When ammonia‐N contents of the water column were 8–16 mg L−1, the total biomass of Vallisneria natans in the first harvest is higher than those in the second harvest, and the total chlorophyll concentration, MDA and free proline of the plants became significantly low. It indicates that high ammonia nitrogen (>8 mg L−1) of the water column inhibit the growth of V. natans. The total biomass, the total chlorophyll concentration of plants in the high nutrient sediment is higher than those in the low nutrient sediment, suggesting that high sediments nutrient promote the growth of V. natans. Therefore, using V. natans for water ecological restoration, the water should meet the ammonia nitrogen content of <8 mg L−1. Moreover, dredging eutrophication sediment is probably not necessary.