Converts

Distribution by Scientific Domains
Distribution within Chemistry


Selected Abstracts


Interstitial Fibrosis Quantification in Renal Transplant Recipients Randomized to Continue Cyclosporine or Convert to Sirolimus

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 11 2009
A. Servais
Conversion from cyclosporine (CsA) to sirolimus at week 12 after kidney transplantation is associated with a significant improvement in renal function. The aim of this analysis was to investigate the effect of this conversion on interstitial fibrosis (IF), a hallmark of chronic allograft injury, in patients taking part in the CONCEPT trial. This multicenter, prospective, trial included 193 renal recipients randomized at week 12 to switch from CsA to sirolimus or to continue CsA, with mycophenolate mofetil. Routine biopsy with automated, quantified assessment of IF by a program of color segmentation was performed at 1 year in 121 patients. At 1 year, renal function was significantly improved in the conversion group as assessed by estimated GFR (MDRD) and measured GFR. Biopsy results, however, showed no between-group difference in percentage of IF. Calculated GFR at 1 year was significantly associated with the percentage of IF (p = 0.004, R2= 0.07). By multivariate analysis diabetic patients had more fibrosis than non-diabetic patients. In conclusion, although kidney transplant patients converted from CsA to sirolimus showed significant improvement in renal function, we found no difference of IF on 1-year biopsies. [source]


ChemInform Abstract: Triisobutylaluminum (TIBA) as a Reagent to Convert 2,2-Dimethoxyalkanes to 2-Methoxy-1-alkenes.

CHEMINFORM, Issue 48 2001
Gustavo Cabrera
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]


Glutamine Nitrogen and Ammonium Nitrogen Supplied as a Nitrogen Source Is Not Converted into Nitrate Nitrogen of Plant Tissues of Hydroponically Grown Pak-Choi (Brassica chinensis L.)

JOURNAL OF FOOD SCIENCE, Issue 2 2009
H.-J. Wang
ABSTRACT:, Many vegetables, especially leafy vegetables, accumulate NO,3 -N in their edible portions. High nitrate levels in vegetables constitute a health hazard, such as cancers and blue baby syndrome. The aim of this study was to determine if (1) ammonium nitrogen (NH+4 -N) and glutamine-nitrogen (Gln-N) absorbed by plant roots is converted into nitrate-nitrogen of pak-choi (Brassica chinensis L.) tissues, and (2) if nitrate-nitrogen (NO,3 -N) accumulation and concentration of pak-choi tissues linearly increase with increasing NO,3 -N supply when grown in nutrient solution. In experiment 1, 4 different nitrogen treatments (no nitrogen, NH+4 -N, Gln-N, and NO,3 -N) with equal total N concentrations in treatments with added N were applied under sterile nutrient medium culture conditions. In experiment 2, 5 concentrations of N (from 0 to 48 mM), supplied as NO,3 -N in the nutrient solution, were tested. The results showed that Gln-N and NH+4 -N added to the nutrient media were not converted into nitrate-nitrogen of plant tissues. Also, NO,3 -N accumulation in the pak-choi tissues was the highest when plants were supplied 24 mM NO,3 -N in the media. The NO,3 -N concentration in plant tissues was quadratically correlated to the NO,3 -N concentration supplied in the nutrient solution. [source]


Titelbild: Design and Folding of [GluA4(O,ThrB30)]Insulin ("Ester Insulin"): A Minimal Proinsulin Surrogate that Can Be Chemically Converted into Human Insulin (Angew. Chem.

ANGEWANDTE CHEMIE, Issue 32 2010
32/2010)
Die effiziente chemische Totalsynthese von Insulin war über 40,Jahre lang eine Herausforderung. In ihrer Zuschrift auf S.,5621,ff. zeigen Y. Sohma, S.,B.,H. Kent und Mitarbeiter, dass eine Ester-verknüpfte "Nulllängen"-Vorstufe genauso effizient faltet wie Volllängen-Proinsulin und leicht durch Verseifung in das vollständig aktive Insulin überführt werden kann. (Titelbild: D. Kent nach einem Entwurf von Y. Sohma.) [source]


Design and Folding of [GluA4(O,ThrB30)]Insulin ("Ester Insulin"): A Minimal Proinsulin Surrogate that Can Be Chemically Converted into Human Insulin,

ANGEWANDTE CHEMIE, Issue 32 2010
Youhei Sohma Prof.
Insulinfaltung: Ein esterverknüpftes Polypeptid-Proinsulinsurrogat faltet effizient unter Disulfidbindungsbildung und lässt sich zum nativen Insulin mit voller biologischer Aktivität verseifen. Diese Strategie vermeidet die mäßig erfolgreiche Kombination der individellen Insulin-A- und -B-Ketten und bietet einen einfachen und effektiven Ansatz zur chemischen Totalsynthese von Humaninsulin und dessen Analoga. [source]


From the Pursuit of Converts to the Relief of Refugees: The Maryknoll Sisters in Twentieth,Century Hong Kong

THE HISTORIAN, Issue 2 2002
Cindy Yik, yi Chu
[source]


Pre-Islamic Arab Converts to Christianity in Mecca and Medina: An Investigation into the Arabic Sources

THE MUSLIM WORLD, Issue 1 2005
Ghada Osman
First page of article [source]


Could chronic pain and spread of pain sensation be induced and maintained by glial activation?

ACTA PHYSIOLOGICA, Issue 1-2 2006
E. Hansson
Abstract An injury often starts with acute physiological pain, which becomes inflammatory or neuropathic, and may sometimes become chronic. It has been proposed recently that activated glial cells, astrocytes and microglia within the central nervous system could maintain the pain sensation even after the original injury or inflammation has healed, and convert it into chronic by altering neuronal excitability. Glial cell activation has also been proposed to be involved in the phenomenon of spread of pain sensation ipsilaterally or to the contralateral side (i.e. mirror image pain). Substance P and calcitonin gene-related peptide, released due to an inflammatory process, interact with the endothelial cells of the blood,spinal cord and blood,brain barriers. The barriers open partially and substances may influence adjacent glial cells. Such substances are also released from neurones carrying the ,pain message' all the way from the injury to the cerebral cortex. Pro-inflammatory cytokines may be released from the microglial cells, and astroglial Ca2+ -transients or oscillations may spread within the astroglial networks. One theory is that Ca2+ -oscillations could facilitate the formation of new synapses. These new synapses could establish neuronal contacts for maintaining and spreading the pain sensation. If this theory holds true, it is possible that Ca2+ waves, production of cytokines and growth factors could be modified by selective anti-inflammatory drugs to achieve a balance in the activities of the different intercellular and intracellular processes. This paper reviews current knowledge about glial mechanisms underlying the phenomena of chronic pain and spread of the pain sensation. [source]


The apical ectodermal ridge in the pectoral fin of the Australian Lungfish (Neoceratodus forsteri): keeping the fin to limb transition in the fold

ACTA ZOOLOGICA, Issue 2009
Verity S. Hodgkinson
Abstract The apical ectodermal ridge (AER) in Neoceratodus develops after an initial period of mesenchymal proliferation and outgrowth of the fin bud and persists until chondrogenesis of the stylopod and zeugopod is initiated. At this time, the lateral margins of the AER convert to the fin fold leading to subsequent development of the dermal fin skeleton. Thorogood's (1991) fin fold model predicts that the AER should persist longer in Neoceratodus than it does in actinopterygians because of the comparatively extensive endochondral skeleton in lungfish. While the AER does persist into early chondrogenesis and is extended compared to actinopterygians (lost before fin radial chondrogenesis) it does not persist into further stages of chondrogenesis, providing partial support for Thorogood's model. Fgf8 appears in the lungfish fin epithelium during the initial period of fin outgrowth before a physical AER forms, when Fgf8 is restricted to the AER plus the preaxial and postaxial epithelium immediately adjacent to the AER. Fgf8 is no longer detected after the AER is replaced by a fin fold. Neoceratodus appears to provide a halfway point between ray fins and limbs during very early development as Thorogood proposed, but not precisely for the reasons his model suggests. [source]


Role of Transthoracic Echocardiography in Atrial Fibrillation

ECHOCARDIOGRAPHY, Issue 4 2000
RICHARD W. ASINGER M.D.
Atrial fibrillation is a major clinical problem that is predicted to be encountered more frequently as the population ages. The clinical management of atrial fibrillation has become increasingly complex as new therapies and strategies have become available for ventricular rate control, conversion to sinus rhythm, maintenance of sinus rhythm, and prevention of thromboembolism. Clinical and transthoracic echocardiographic features are important in determining etiology and directing therapy for atrial fibrillation. Left atrial size, left ventricular wall thickness, and left ventricular function have independent predictive value for determining the risk of developing atrial fibrillation. Left atrial size may have predictive value in determining the success of cardioversion and maintaining sinus rhythm in selected clinical settings but has less value in the most frequently encountered group, patients with nonvalvular atrial fibrillation, in whom the duration of atrial fibrillation is the most important feature. When selecting pharmacological agents to control ventricular rate, convert to sinus rhythm, and maintain normal sinus rhythm, transthoracic echocardiography (TTE) allows noninvasive evaluation of left ventricular function and hence guides management. The combination of clinical and transthoracic echocardiographic features also allows risk stratification for thromboembolism and hemorrhagic complications in atrial fibrillation. High-risk clinical features for thromboembolism supported by epidemiological observations, results of randomized clinical trials, and meta-analyses include rheumatic valvular heart disease, prior thromboembolism, congestive heart failure, hypertension, older (> 75 years old) women, and diabetes. Small series of cases also suggest those with hyperthyroidism and hypertrophic cardiomyopathy are at high risk. TTE plays a unique role in confirming or discovering high-risk features such as rheumatic valvular disease, hypertrophic cardiomyopathy, and decreased left ventricular function. Validation of the risk stratification scheme used in the Stroke Prevention in Atrial Fibrillation-III trial is welcomed by clinicians who are faced daily with balancing the benefit and risks of anticoagulation to prevent thromboembolism inpatients with atrial fibrillation. [source]


Mössbauer Investigation of Peroxo Species in the Iron(III),EDTA,H2O2 System

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 21 2005
Virender K. Sharma
Abstract The reaction of a diiron(III),EDTA complex with H2O2 in alkaline medium is studied by Mössbauer spectroscopy in conjunction with the rapid-freeze/quench technique in order to identify possible intermediate species during the formation and decomposition of the purple (EDTA)FeIII(,2 -O2)3, complex ion. Starting from the six-coordinate [FeIIIEDTA], species at acidic pH, it is demonstrated that mononuclear complexes formed at a pH of about 1 are convert into the diiron(III),EDTA complex [(EDTA)FeIII -O-FeIII(EDTA)]4, upon raising the pH to around 10.4. H2O2 reacts with the diiron(III) complex to give peroxide/hydroperoxide related adducts. Initially, the reaction tears apart the dimers to form a peroxo adduct, namely the seven-coordinate mononuclear [(EDTA)FeIII(,2 -O2)]3,, which is stable only at very high pH. The decomposition of this peroxo adduct gives two new species, which are reported for the first time. The Mössbauer parameters of these species suggest a six-coordinate ,-peroxodiiron(III) complex [(EDTA)FeIII -(OO)-FeIII(EDTA)]4, and a seven-coordinate ,-hydroxo-,-peroxodiiron(III) complex [(EDTA)FeIII -(OO)(OH)-FeIII(EDTA)]5,. A badly resolved, extremely broad component is observed in the Mössbauer spectra during the conversion of the monomer to dimeric peroxo species, which may be attributed to the short-lived [(EDTA)FeIII -OO]3, or [(EDTA)FeIII -OOH]2, intermediate species. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]


Generation of Monodisperse Inorganic,Organic Janus Microspheres in a Microfluidic Device

ADVANCED FUNCTIONAL MATERIALS, Issue 10 2009
Naveen Prasad
Abstract This study presents a simple synthetic approach for the in situ preparation of monodisperse hybrid Janus microspheres (HJM) having organic and inorganic parts in a PDMS-based microfluidic device. Based on the mechanism of shear-force-driven break-off, merged droplets of two photocurable oligomer solutions having distinctive properties are generated into an immiscible continuous phase. Functionalized perfluoropolyether (PFPE) as the organic phase and hydrolytic allylhydridopolycarbosilane (AHPCS) as the inorganic phase are used for the generation in aqueous medium of HJM with well-defined morphology and high monodispersity (average diameter of 162,µm and a 3.5% coefficient of variation). The size and shape of the HJM is controlled by varying the flow rate of the disperse and continuous phases. The HJM have two distinctive regions: a hydrophobic hemisphere (PFPE) having a smooth surface and a relatively hydrophilic region (AHPCS) with a rough, porous surface. In addition, pyrolysis and subsequent oxidation of these HJM convert them into SiC-based ceramic hemispheres through the removal of the organic portion and etching off the silica shell. The selective incorporation of magnetic nanoparticles into the inorganic part shows the feasibility of the forced assembly of HJM in an applied magnetic field. [source]


Specific thermal ablation of tumor cells using single-walled carbon nanotubes targeted by covalently-coupled monoclonal antibodies

INTERNATIONAL JOURNAL OF CANCER, Issue 12 2009
Radu Marches
Abstract CD22 is broadly expressed on human B cell lymphomas. Monoclonal anti-CD22 antibodies alone, or coupled to toxins, have been used to selectively target these tumors both in SCID mice with xenografted human lymphoma cell lines and in patients with B cell lymphomas. Single-walled carbon nanotubes (CNTs) attached to antibodies or peptides represent another approach to targeting cancer cells. CNTs convert absorbed near-infrared (NIR) light to heat, which can thermally ablate cells that have bound the CNTs. We have previously demonstrated that monoclonal antibodies (MAbs) noncovalently coupled to CNTs can specifically target and kill cells in vitro. Here, we describe the preparation of conjugates in which the MAbs are covalently conjugated to the CNTs. The specificity of both the binding and NIR-mediated killing of the tumor cells by the MAb-CNTs is demonstrated by using CD22+CD25, Daudi cells, CD22,CD25+ phytohemagglutinin-activated normal human peripheral blood mononuclear cells, and CNTs covalently modified with either anti-CD22 or anti-CD25. We further demonstrate that the stability and specificity of the MAb-CNT conjugates are preserved following incubation in either sodium dodecyl sulfate or mouse serum, indicating that they should be stable for in vivo use. © 2009 UICC [source]


Adaptive/robust time-varying stabilization of second-order non-holonomic chained form with input uncertainties

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 15 2002
B. L. Ma
Abstract Adaptive and robust time-varying control schemes are constructed to stabilize second-order non-holonomic chained form in the presence of input uncertainties. The proposed control schemes guarantee that all the state variables converge to zero asymptotically in spite of input uncertainties, and are applied to the stabilization of a planar rigid body driven by active force and torque with unknown inertia and geometric parameters. The basic idea of the proposed stabilization schemes is to first convert the non-holonomic system into a linear time-varying form by time-varying co-ordinate transformation, and then design control laws to stabilize the converted linear time-varying system. Copyright © 2002 John Wiley & Sons, Ltd. [source]


The Squam Lake Report: Fixing the Financial System,

JOURNAL OF APPLIED CORPORATE FINANCE, Issue 3 2010
Kenneth French
In these excerpts from The Squam Lake Report, fifteen distinguished economists analyze where the global financial system failed, and how such failures might be prevented (or at least their damage better contained) in the future. Although there were many contributing factors to the crisis,including "agency" problems throughout the financial system and a bankruptcy code poorly suited for reorganizing financial firms,at the core of the problem is a potential conflict between the risk-taking proclivity of financial institutions and the interests of the economy at large that must be managed at least in part through more effective regulation. The Squam Lake Report provides a nonpartisan plan to transform the regulation of financial markets in ways designed to limit systemic risk while preserving,to the extent possible and prudent,the economies of scale and scope that justify the existence of today's large financial institutions. To reduce the risks that large banks will fail, the authors call for higher capital requirements based on more effective assessments of the risks of bank assets and liabilities, as well as a new systemic regulator that should be part of the central bank. To reduce the costs of failure when it occurs, the authors propose that banks be required to create "living wills" laying out their plan to sell assets or shut down operations in the event of financial trouble. As part of that plan, regulators are urged to "aggressively encourage" banks to issue "contingent" debt capital securities that convert into equity. [source]


A low voltage highly linear 24-GHz down conversion mixer in 0.18-,m CMOS

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 10 2007
Masum Hossain
Abstract A K-band low voltage, highly linear folded Gilbert cell mixer in 0.18-,m CMOS is presented. An optimization technique been introduced which is particularly applicable to Gilbert cell type mixers. This technique has been experimentally verified with a down conversion mixer fabricated in a 0.18-,m CMOS process. Utilizing PMOS devices in the transconductance stage and using a 2-V supply voltage, the mixer can down convert from 24 GHz to 10 MHz with an input referred third order intercept of +20 dBm and a conversion gain of 2 dB. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2547,2552, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22759 [source]


convert: A user-friendly program to reformat diploid genotypic data for commonly used population genetic software packages

MOLECULAR ECOLOGY RESOURCES, Issue 2 2004
Jeffrey C. Glaubitz
Abstract convert is a user-friendly, 32-bit Windows program that facilitates ready transfer of codominant, diploid genotypic data amongst commonly used population genetic software packages. convert reads input files in its own ,standard' data format, easily produced from an excel file of diploid, codominant marker data, and can convert these to the input formats of the following programs: gda, genepop, arlequin, popgene, microsat, phylip, and structure. convert can also read input files in genepop format. In addition, convert can produce a summary table of allele frequencies in which private alleles and the sample sizes at each locus are indicated. [source]


Structural characterization of unphosphorylated STAT5a oligomerization equilibrium in solution by small-angle X-ray scattering

PROTEIN SCIENCE, Issue 4 2009
Pau Bernadó
Abstract Signal transducer and activator of transcription (STAT) proteins play a crucial role in the activation of gene transcription in response to extracellular stimuli. The regulation and activity of these proteins require a complex rearrangement of the domains. According to the established models, based on crystallographic data, STATs convert from a basal antiparallel inactive dimer into a parallel active one following phosphorylation. The simultaneous analysis of small-angle X-ray scattering data measured at different concentrations of unphosphorylated human STAT5a core domain unambiguously identifies the simultaneous presence of a monomer and a dimer. The dimer is the minor species but could be structurally characterized by SAXS in the presence of the monomer using appropriate computational tools and shown to correspond to the antiparallel assembly. The equilibrium is governed by a moderate dissociation constant of Kd , 90 ,M. Integration of these results with previous knowledge of the N-terminal domain structure and dissociation constants allows the modeling of the full-length protein. A complex network of intermolecular interactions of low or medium affinity is suggested. These contacts can be eventually formed or broken to trigger the dramatic modifications in the dimeric arrangement needed for STAT regulation and activity. [source]


Biochemical characterization of rab proteins from Bombyx mori,

ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 2 2009
Tomohide Uno
Abstract The small GTPases known as Rab proteins are key regulators of membrane trafficking. We used RT-PCR to isolate cDNA clones of insect-specific Rab proteins (BRabN1 and BRabN2) showing low homology with known Rab proteins from other animals, from mRNA of Bombyx mori. These 2 Rabs were produced in Escherichia coli and purified. BRabN1 bound [3H]-GDP and [35S]-GTP,S with dissociation constants of 0.087 × 10,6,M and 1.02 × 10,6,M, respectively, whereas those of BRabN2 were 0.546 × 10,6,M and 1.02 × 10,6,M, respectively. Binding of [35S]-GTP,S to BRabN1 and N2 was inhibited by GDP and GTP. The GTP-hydrolysis activities of BRabN1 and N2 were 154 and 35.5,mmol/min/mole, respectively, and bound [35S]-GTP,S was exchanged efficiently with GTP. BRabN1 also showed ATPase activity and exchange of [35S]-GTP,S with ATP. Monoclonal antibodies against BRabN1 and N2 did not recognize any other Rab proteins, and Western blotting using the anti-BRabN1 antibody revealed a single band in the testis of B. mori. These results suggest that BRabN1 and N2 of B. mori bind GTP, convert from the GTP-bound state to the GDP-bound state by intrinsic GTP hydrolysis activity, and return to the GTP-bound state with the exchange, and that BRabN1 is specifically expressed in testis. Arch. Insect Biochem. Physiol. 2008. © 2008 Wiley-Liss, Inc. [source]


Structure of the d -alanylgriseoluteic acid biosynthetic protein EhpF, an atypical member of the ANL superfamily of adenylating enzymes

ACTA CRYSTALLOGRAPHICA SECTION D, Issue 6 2010
Asim K. Bera
The structure of EhpF, a 41,kDa protein that functions in the biosynthetic pathway leading to the broad-spectrum antimicrobial compound d -alanylgriseoluteic acid (AGA), is reported. A cluster of approximately 16 genes, including ehpF, located on a 200,kbp plasmid native to certain strains of Pantoea agglomerans encodes the proteins that are required for the conversion of chorismic acid to AGA. Phenazine-1,6-dicarboxylate has been identified as an intermediate in AGA biosynthesis and deletion of ehpF results in accumulation of this compound in vivo. The crystallographic data presented here reveal that EhpF is an atypical member of the acyl-CoA synthase or ANL superfamily of adenylating enzymes. These enzymes typically catalyze two-step reactions involving adenylation of a carboxylate substrate followed by transfer of the substrate from AMP to coenzyme A or another phosphopantetheine. EhpF is distinguished by the absence of the C-terminal domain that is characteristic of enzymes from this family and is involved in phosphopantetheine binding and in the second half of the canonical two-step reaction that is typically observed. Based on the structure of EhpF and a bioinformatic analysis, it is proposed that EhpF and EhpG convert phenazine-1,6-dicarboxylate to 6-formylphenazine-1-carboxylate via an adenylyl intermediate. [source]


Serum HER-2/neu conversion to positive at the time of disease progression in patients with breast carcinoma on hormone therapy

CANCER, Issue 2 2005
Allan Lipton M.D.
Abstract BACKGROUND Prolonged exposure of breast carcinoma cells in vitro to tamoxifen results in tamoxifen resistance. Tamoxifen-resistant cells express increased HER-2/neu mRNA and protein. The objective of this study was to determine whether patients with metastatic or locally advanced breast carcinoma who have negative serum HER-2/neu status at the initiation of first-line hormone therapy with letrozole or tamoxifen convert to positive serum HER-2/neu status at the time of disease progression and to determine whether serum HER-2/neu conversion to positive status is associated with response to therapy and overall survival. METHODS Serum samples were obtained at baseline and at the time of disease progression from 240 patients who initially had negative serum HER-2/neu status (< 15 ng/mL). A manual microtiter, enzyme-linked immunosorbent assay that was specific for the extracellular domain of the HER-2/neu (c- erbB-2) oncoprotein product was used to quantitate serum levels. RESULTS Among 240 patients, 61 patients (26%) converted from serum HER-2/neu negative to positive (> 15 ng/mL) at the time of disease progression. Thirty-two of 129 patients (25%) who were treated with tamoxifen and 29 of 111 patients (26%) who were treated with letrozole became converted to positive serum HER-2/neu status at the time of disease progression. The response rate and the time to disease progression on first-line hormone therapy were not affected by serum HER-2/neu conversion. The survival of patients who converted to positive serum HER-2/neu status was significantly shorter compared with the survival of patients who remained negative for serum HER-2/neu. A multivariate analysis revealed that conversion to positive serum HER-2/neu status was an independent prognostic variable for survival. CONCLUSIONS Conversion to positive serum HER-2/neu status occurred in approximately 25% of patients who received first-line hormone therapy. Conversion to serum HER-2/neu -positive status occurred with equal frequency in antiestrogen and aromatase-inhibitor therapy. The current results showed that serum conversion to HER-2/neu -positive status was an independent risk factor for decreased survival in patients with breast carcinoma. Cancer 2005. © 2005 American Cancer Society. [source]


Three Polymorphic Forms of the Co-Crystal 4,4,-Bipyridine/Pimelic Acid and their Structural, Thermal, and Spectroscopic Characterization

CHEMISTRY - A EUROPEAN JOURNAL, Issue 32 2008
Dario Braga Prof.
Abstract Three crystal forms of the co-crystal 4,4,-bipy/pimelic acid (bipy: bipyridine), [NH4C5 -C5H4N],[HOOC(CH2)5COOH], have been prepared and their relationship investigated by single-crystal X-ray diffraction, variable-temperature X-ray powder diffraction, differential scanning calorimetry and solid-state NMR spectroscopy. Both X-ray and NMR spectroscopic results indicate that no proton transfer takes place, that is, the three crystal forms are true co-crystals of neutral molecules. Forms,I and II both convert into Form,III at high temperature, Forms,II and III being the thermodynamically stable forms at room and high temperature, respectively. [source]


CO2 Fixation and Transformation by a Dinuclear Copper Cryptate under Acidic Conditions

CHEMISTRY - AN ASIAN JOURNAL, Issue 6 2007
Jia-Mei Chen
Abstract CO2 fixation and transformation by metal complexes continuously receive attention from the viewpoint of carbon resources and environmental concerns. We found that the dinuclear copper(II) cryptate [Cu2L1](ClO4)4 (1; L1=N[(CH2)2NHCH2(m -C6H4)CH2NH-(CH2)2]3N) can easily take up atmospheric CO2 even under weakly acidic conditions at room temperature and convert it from bicarbonate into carbonate monoesters in alcohol solution. The compounds [Cu2L1(, - O2COH)](ClO4)3 (2), [Cu2L1(,-O2COR)](ClO4)3 (3: R=CH3; 4: R=C2H5; 5: R=C3H7; 6: R=C4H9; 7: R=C5H11; 8: R=CH2CH2OH), [Cu2L1(, - O2CCH3)](ClO4)3 (9), and [Cu2L1(OH2)(NO3)](NO3)3 (10) were characterized by IR spectroscopy and ESI-MS. The crystal structures of 2,6 and 10 were studied by single-crystal X-ray diffraction analysis. On the basis of the crystal structures, solution studies, and DFT calculations, a possible mechanism for CO2 fixation and transformation is given. [source]


Places of Privileged Consumption Practices: Spatial Capital, the Dot-Com Habitus, and San Francisco's Internet Boom

CITY & COMMUNITY, Issue 3 2008
Ryan Centner
Drawing from interviews and fieldwork with former dot-com workers in San Francisco, this article examines how their spatialized consumption practices formed exclusionary places of privilege during the city's millennial boom of internet companies. I focus especially on the personalized deployment of uneven social power in situations where space is at stake. After considering how this group differed from a history of other urban newcomers, I develop a framework for addressing their spatial effects as gentrification involving privileged consumption practices that surpass residential encroachments. I argue there is an exertion of spatial capital that represents the misrecognition of territorial claims, enabling this cohort to literally take place. I show this through several consumption practices that convert to and from economic, cultural, and social capital. A concluding discussion reflects on the usefulness of this case and framework for reinvigorating key urban-sociological analytics while confronting influential but unsociological characterizations of contemporary city life. [source]


Confirmation Ministry in the Batak Church

DIALOG, Issue 3 2002
Binsar Nainggolan
Historically, confirmation ministry among Batak's took the form of missionaries presenting the Christian religion in an apologetic and persuasive tone, in an effort to ready Batak converts for Baptism. Today, confirmation ministry among Batak Christians is understood as a fleshing out of what it means to be baptized into the church community. This article explores the method and aims of the confirmation rite and ministry among Batak Christians. [source]


The Autocracy of Love and the Legitimacy of Empire: Intimacy, Power and Scandal in Nineteenth-Century Metlakahtlah

GENDER & HISTORY, Issue 2 2004
Adele Perry
This paper examines the politics of intimacy, power, and scandal at Metlakahtlah, a Church of England mission village in northern British Columbia, Canada, from 1862 to 1885, in order to cast light on settler colonialism and its aftermath. It particularly examines Metlakahtlah's main missionary, William Duncan, his relationships with young female converts and missionary women, and, perhaps more importantly, the stories that were told about them. Stories of Duncan's relationships with young Tsimshian women that circulated throughout settler society reveal the central place of sexuality to both critiques and defences of imperialism, and cast new light on contemporary politics around the historical experience of Indigenous children in settler colonies like Australia and Canada. [source]


Thiofenchone s -methylide and its spiro-1,3,4-thiadiazoline precursor

HETEROATOM CHEMISTRY, Issue 3 2001
Rolf Huisgen
Spiro[fenchane-2,2,-(1,3,4)-thiadiazoline] (6), prepared from thiofenchone and diazomethane, extrudes N2 (t1/2 22 min, 46°C, toluene) and furnishes the S-methylide 7 which, in turn, closes the thiirane ring or else is intercepted by 1,3-cycloadditions to dipolarophiles (tetracyanoethylene, maleic anhydride, N-methyl-1,2,4-triazoline-3,5-dione, aromatic thioketones). When thiocarbonyl S-methylide 7 is set free in methanol, fenchone S,O-dimethylacetal is formed as an HX adduct. Catalysis by acetic acid converts 7 to 1-(methylthio)-,-fenchene (25) by way of a Wagner-Meerwein rearrangement. The addition of diazomethane to thiocampher leads, via thiadiazoline 12, to thiocamphor S-methylide; the latter undergoes a 1,4-H shift, thus affording 2-methylthio-2-bornene (11). © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:136,145, 2001 [source]


Functional and structural analysis of five mutations identified in methylmalonic aciduria cbIB type,

HUMAN MUTATION, Issue 9 2010
Ana Jorge-Finnigan
Abstract ATP:cob(I)alamin adenosyltransferase (ATR, E.C.2.5.1.17) converts reduced cob(I)alamin to the adenosylcobalamin cofactor. Mutations in the MMAB gene encoding ATR are responsible for the cblB type methylmalonic aciduria. Here we report the functional analysis of five cblB mutations to determine the underlying molecular basis of the dysfunction. The transcriptional profile along with minigenes analysis revealed that c.584G>A, c.349-1G>C, and c.290G>A affect the splicing process. Wild-type ATR and the p.I96T (c.287T>C) and p.R191W (c.571C>T) mutant proteins were expressed in a prokaryote and a eukaryotic expression systems. The p.I96T protein was enzymatically active with a KM for ATP and KD for cob(I)alamin similar to wild-type enzyme, but exhibited a 40% reduction in specific activity. Both p.I96T and p.R191W mutant proteins are less stable than the wild-type protein, with increased stability when expressed under permissive folding conditions. Analysis of the oligomeric state of both mutants showed a structural defect for p.I96T and also a significant impact on the amount of recovered mutant protein that was more pronounced for p.R191W that, along with the structural analysis, suggest they might be misfolded. These results could serve as a basis for the implementation of pharmacological therapies aimed at increasing the residual activity of this type of mutations. Hum Mutat 31:1033,1042, 2010. © 2010 Wiley-Liss, Inc. [source]


Desorption kinetics of model polar stratospheric cloud films measured using Fourier Transform Infrared Spectroscopy and Temperature-Programmed Desorption

INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 5 2001
Birgit G. Koehler
This study combines Fourier transform infrared (FTIR) spectroscopy and temperature-programmed desorption to examine the evaporation kinetics of thin films of crystalline nitric acid hydrates, solid amorphous H2O/HNO3 mixtures, H2O,ice, ice coated with HCl, and solid HNO3. IR spectroscopy measured the thickness of each film as it evaporated, either at constant temperature or during a linear temperature ramp (temperature-programmed infrared, TPIR). Simultaneously, a mass spectrometer measured the rate of evaporation directly by monitoring the evolution of the molecules into the gas phase (temperature-programmed desorption, TPD). Both TPIR and TPD data provide a measurement of the desorption rate and yield the activation energy and preexponential factor for desorption. TPD measurements have the advantage of producing many data points but are subject to interference from experimental difficulties such as uneven heating from the edge of a sample and sample-support as well as pumping-speed limitations. TPIR experiments give clean but fewer data points. Evaporation occurred between 170 and 215 K for the various films. Ice evaporates with an activation energy of 12.9 ± 1 kcal/mol and a preexponential factor of 1 × 1032±1.5 molec/cm2 s, in good agreement with the literature. The beta form of nitric acid trihydrate, ,,NAT, has an Edes of 15.6 ± 2 kcal/mol with log A = 34.3 ± 2.3; the alpha form of nitric acid trihydrate, ,,NAT, is around 17.7 ± 3 kcal/mol with log A = 37.2 ± 4. For nitric acid dihydrate, NAD, Edes is 17.3 ± 2 kcal/mol with log A = 35.9 ± 2.6; for nitric acid monohydrate, NAM, Edes is 13 ± 3 kcal/mol with log A = 31.4 ± 3. The ,,NAT converts to ,,NAT during evaporation, and the amorphous solid H2O/HNO3 mixtures crystallize during evaporation. The barrier to evaporation for pure nitric acid is 14.6 ± 3 kcal/mol with log A = 34.4 ± 3. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 295,309, 2001 [source]


Raman spectroscopy for spinline crystallinity measurements.

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008

Abstract The original Doufas,McHugh two-phase microstructural/constitutive model for stress-induced crystallization is expanded to polyolefin systems and validated for its predictive capability of online Raman crystallinity and spinline tension data for two Dow homopolymer polypropylene resins. The material parameters,inputs to the model,are obtained from laboratory-scale material characterization data, that is, oscillatory dynamic shear, rheotens (melt extensional rheology), and differential scanning calorimetry data. The same set of two stress-induced crystallization material/molecular parameters are capable of predicting the crystallinity profiles along the spinline and fiber tension very well overall for a variety of industrial fabrication conditions. The model is capable of predicting the freeze point, which is shown, for the first time, to correlate very well with the measured stick point (i.e., the point in the spinline at which the fiber bundle converts from a solid-like state to a liquid-like state and sticks to a solid object such as a glass rod). The model quantitatively captures the effects of the take-up speed, throughput, and melt flow rate on the crystallization rate of polypropylene due to stress-induced crystallization effects. This validated modeling approach has been used to guide fiber spinning for rapid product development. The original Doufas,McHugh stress-induced crystallization model is shown to be numerically robust for the simulation of steady polypropylene melt spinning over a wide range of processing conditions without issues of discontinuities due to the onset of the two-phase constitutive formulation downstream of the die face, at which crystallization more realistically begins. Because of the capturing of the physics of polypropylene fiber spinning and the very good model predictive power, the approximations of the original Doufas,McHugh model are asserted to be reasonable. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]