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Chemistry Approach (chemistry + approach)
Kinds of Chemistry Approach Selected AbstractsClick Chemistry Approach to Rhodamine B-Capped Polyrotaxanes and their Unique Fluorescence PropertiesMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 20 2009Jiayan Wu Abstract A fluorescent polyrotaxane (PR) made from the diazido-poly(ethylene glycol) (N3 -PEG-N3) axis, , -cyclodextrins, and alkyne-functionalized rhodamine B (RhB-alk) stoppers via Cu(I)-catalyzed azide,alkyne click chemistry is reported. A nanowire-like morphology of the prepared fluorescent PRs was visualized by atomic force microscopy. The fluorescence emission intensities of RhB-capped PEG (RhB-PEG-RhB) and the PR were much higher than that of neat RhB or RhB-alk with the same concentration of RhB fluorophore in both dimethylsulfoxide and alkaline aqueous solutions. Fluorescence lifetimes were detected as 3.59, 3.31, 2.99, and 2.99,ns for neat RhB, RhB-alk, RhB-PEG-RhB, and the PR, respectively. The PRs with unique fluorescence properties might have further applications in the fields of biomedicine and bionanotechnology. [source] ChemInform Abstract: Novel Anthraquinone Derivatives: Synthesis via Click Chemistry Approach and Their Induction of Apoptosis in BGC Gastric Cancer Cells via Reactive Oxygen Species(ROS)-Dependent Mitochondrial Pathway.CHEMINFORM, Issue 17 2009Shaoru Wang Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 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] A Green Chemistry Approach to the Synthesis of Isatoic Anhydrides from Anthranilic Acid Derivatives.CHEMINFORM, Issue 8 2007Rajyashree Chakravorty Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] A Simplified Green Chemistry Approach to the Biginelli Reaction Using "Grindstone Chemistry".CHEMINFORM, Issue 7 2005Ajay K. Bose Abstract For Abstract see ChemInform Abstract in Full Text. [source] CaF2 As a Quasilinear Molecule: The Vibrational,Rotational Energy Levels Predicted by ab initio Quantum Chemistry Approach.CHEMINFORM, Issue 52 2004Jacek Koput No abstract is available for this article. [source] Molecular determinants of ligand specificity in family 11 carbohydrate binding modules , an NMR, X-ray crystallography and computational chemistry approachFEBS JOURNAL, Issue 10 2008Aldino Viegas The direct conversion of plant cell wall polysaccharides into soluble sugars is one of the most important reactions on earth, and is performed by certain microorganisms such as Clostridium thermocellum (Ct). These organisms produce extracellular multi-subunit complexes (i.e. cellulosomes) comprising a consortium of enzymes, which contain noncatalytic carbohydrate-binding modules (CBM) that increase the activity of the catalytic module. In the present study, we describe a combined approach by X-ray crystallography, NMR and computational chemistry that aimed to gain further insight into the binding mode of different carbohydrates (cellobiose, cellotetraose and cellohexaose) to the binding pocket of the family 11 CBM. The crystal structure of C. thermocellum CBM11 has been resolved to 1.98 Å in the apo form. Since the structure with a bound substrate could not be obtained, computational studies with cellobiose, cellotetraose and cellohexaose were carried out to determine the molecular recognition of glucose polymers by CtCBM11. These studies revealed a specificity area at the CtCBM11 binding cleft, which is lined with several aspartate residues. In addition, a cluster of aromatic residues was found to be important for guiding and packing of the polysaccharide. The binding cleft of CtCBM11 interacts more strongly with the central glucose units of cellotetraose and cellohexaose, mainly through interactions with the sugar units at positions 2 and 6. This model of binding is supported by saturation transfer difference NMR experiments and linebroadening NMR studies. [source] Unified QSAR & network-based computational chemistry approach to antimicrobials.JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 1 2010Abstract In the previous work, we reported a multitarget Quantitative Structure-Activity Relationship (mt-QSAR) model to predict drug activity against different fungal species. This mt-QSAR allowed us to construct a drug,drug multispecies Complex Network (msCN) to investigate drug,drug similarity (González-Díaz and Prado-Prado, J Comput Chem 2008, 29, 656). However, important methodological points remained unclear, such as follows: (1) the accuracy of the methods when applied to other problems; (2) the effect of the distance type used to construct the msCN; (3) how to perform the inverse procedure to study species,species similarity with multidrug resistance CNs (mdrCN); and (4) the implications and necessary steps to perform a substructural Triadic Census Analysis (TCA) of the msCN. To continue the present series with other important problem, we developed here a mt-QSAR model for more than 700 drugs tested in the literature against different parasites (predicting antiparasitic drugs). The data were processed by Linear Discriminate Analysis (LDA) and the model classifies correctly 93.62% (1160 out of 1239 cases) in training. The model validation was carried out by means of external predicting series; the model classified 573 out of 607, that is, 94.4% of cases. Next, we carried out the first comparative study of the topology of six different drug,drug msCNs based on six different distances such as Euclidean, Chebychev, Manhattan, etc. Furthermore, we compared the selected drug,drug msCN and species,species mdsCN with random networks. We also introduced here the inverse methodology to construct species,species msCN based on a mt-QSAR model. Last, we reported the first substructural analysis of drug,drug msCN using Triadic Census Analysis (TCA) algorithm. © 2009 Wiley Periodicals, Inc. J Comput Chem 2010 [source] ROMP-NMP-ATRP combination for the preparation of 3-miktoarm star terpolymer via click chemistryJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 2 2009Aziz Gozgen Abstract A combination of ring opening metathesis polymerization (ROMP) and click chemistry approach is first time utilized in the preparation of 3-miktoarm star terpolymer. The bromide end-functionality of monotelechelic poly(N -butyl oxanorbornene imide) (PNBONI-Br) is first transformed to azide and then reacted with polystyrene- b -poly(methyl methacrylate) copolymer with alkyne at the junction point (PS- b -PMMA-alkyne) via click chemistry strategy, producing PS-PMMA-PNBONI 3-miktoarm star terpolymer. PNBONI-Br was prepared by ROMP of N -butyl oxanorbornene imide (NBONI) 1 in the presence of (Z)-but-2-ene-1,4-diyl bis(2-bromopropanoate) 2 as terminating agent. PS- b -PMMA-alkyne copolymer was prepared successively via nitroxide-mediated radical polymerization (NMP) of St and atom transfer radical polymerization (ATRP) of MMA. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 497,504, 2009 [source] Control synthesis of iron oxide nanospheres using solution chemistryPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2007M. Z. Wu Abstract A facile solution chemistry approach to the batch synthesis of magnetite nanocrystals is developed. By using different starting materials, the control of particle size and size distribution can be achieved. Detailed investigations into the morphology and size distribution of the final products were carried out with the aid of field emission scanning electronic microscopy (FESEM). The crystal structure was studied by powder X ray diffraction (XRD). Vibrating sample magnetometer (VSM) was used to study the magnetic properties of these sphere-like products. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Highly efficient and selective enrichment of peptide subsets combining fluorous chemistry with reversed-phase chromatographyRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 24 2009Wantao Ying The selective capture of target peptides poses a great challenge to modern chemists and biologists, especially when enriching them from proteome samples possessing extremes in concentration dynamic range and sequence diversity. While approaches based on traditional techniques such as biotin-avidin pairing offer versatile tools to design strategies for selective enrichment, problems are still encountered due to sample loss or poor selectivity of enrichment. Here we show that the recently introduced fluorous chemistry approach has attractive properties as an alternative method for selective enrichment. Through appending a perfluorine group to the target peptide, it is possible to dramatically increase the peptide's hydrophobicity and thus enable facile separation of labeled from non-labeled peptides. Use of reversed-phase chromatography allowed for improved peptide recovery in comparison with results obtained using the formerly reported fluorous bonded phase methods. Furthermore, this approach also allowed for on-line separation and identification of both labeled and unlabeled peptides in a single experiment. The net result is an increase in the confidence of protein identification by tandem mass spectrometry (MS2) as all peptides and subsequent information are retained. Successful off-line and on-line enrichment of cysteine-containing peptides was obtained, and high quality MS2 spectra were obtained by tandem mass spectrometry due to the stability of the tag, allowing for facile identification via standard database searching. We believe that this strategy holds great promise for selective enrichment and identification of low abundance target proteins or peptides. Copyright © 2009 John Wiley & Sons, Ltd. [source] The Formation of Large-Area Conducting Graphene-Like PlateletsCHEMISTRY - A EUROPEAN JOURNAL, Issue 33 2009Riccardo Salvio Abstract The treatment of a suspension of graphite oxide (GO) with sodium azide leads to a material that, after reduction, features amino groups at the top and bottom of the sheets. These groups react through microcontact printing with an isothiocyanate monolayer on a silicon oxide substrate to form covalent bonds that strongly attach to the particles on the surface. With ultrasonication it is possible to obtain exfoliation of the sheets that are not covalently bound to the surface leaving single-layer platelets attached to the substrate. The azido derivative can be also used to functionalize the graphene oxide with long alkylic chains through a click chemistry approach. This functionalization results in the exfoliation of this material in dimethylformamide. The novel materials were fully characterized by different techniques including IR spectroscopy, thermogravimetric analysis (TGA), scanning and transmission electron microscopy (SEM and TEM), X-Ray photoelectron spectroscopy (XPS), and solid state NMR spectroscopy. The material with amino groups, after the reduction step, is conductive with a resistivity only approximately seven times larger than that of unprocessed graphite. This implies that after reduction of the GO, the conjugated sp2 network is largely restored. We consider this to be an important step towards a chemical approach for forming conducting large-area platelet films of single-layer graphene. [source] Provenance of sandstones from the Wakino Subgroup of the Lower Cretaceous Kanmon Group, northern Kyushu, JapanISLAND ARC, Issue 1 2000Daniel K. Asiedu Abstract The Wakino Subgroup is a lower stratigraphic unit of the Lower Cretaceous Kanmon Group. Previous studies on provenance of Wakino sediments have mainly concentrated on either petrography of major framework grains or bulk rock geochemistry of shales. This study addresses the provenance of the Wakino sandstones by integrating the petrographic, bulk rock geochemistry, and mineral chemistry approaches. The proportions of framework grains of the Wakino sandstones suggest derivation from either a single geologically heterogeneous source terrane or multiple source areas. Major source lithologies are granitic rocks and high-grade metamorphic rocks but notable amounts of detritus were also derived from felsic, intermediate and mafic volcanic rocks, older sedimentary rocks, and ophiolitic rocks. The heavy mineral assemblage include, in order of decreasing abundance: opaque minerals (ilmenite and magnetite with minor rutile), zircon, garnet, chromian spinel, aluminum silicate mineral (probably andalusite), rutile, epidote, tourmaline and pyroxene. Zircon morphology suggests its derivation from granitic rocks. Chemistry of chromian spinel indicates that the chromian spinel grains were derived from the ultramafic cumulate member of an ophiolite suite. Garnet and ilmenite chemistry suggests their derivation from metamorphic rocks of the epidote-amphibolite to upper amphibolite facies though other source rocks cannot be discounted entirely. Major and trace element data for the Wakino sediments suggest their derivation from igneous and/or metamorphic rocks of felsic composition. The major element compositions suggest that the type of tectonic environment was of an active continental margin. The trace element data indicate that the sediments were derived from crustal rocks with a minor contribution from mantle-derived rocks. The trace element data further suggest that recycled sedimentary rocks are not major contributors of detritus. It appears that the granitic and metamorphic rocks of the Precambrian Ryongnam Massif in South Korea were the major contributors of detritus to the Wakino basin. A minor but significant amount of detritus was derived from the basement rocks of the Akiyoshi and Sangun Terrane. The chromian spinel appears to have been derived from a missing terrane though the ultramafic rocks in the Ogcheon Belt cannot be discounted. [source] Medicinal chemistry approaches for the treatment and prevention of Alzheimer's diseaseMEDICINAL RESEARCH REVIEWS, Issue 1 2003S.O. Bachurin Abstract Alzheimer's disease (AD) is the most common form of dementia, which is characterised by progressive deterioration of memory and higher cortical functions that ultimately result in total degradation of intellectual and mental activities. Modern strategies in the search of new therapeutic approaches are based on the morphological and biochemical characteristics of AD, and focused on following directions: agents that compensate the hypofunction of cholinergic system, agents that interfere with the metabolism of beta-amyloid peptide, agents that protect nerve cells from toxic metabolites formed in neurodegenerative processes, agents that activate other neurotransmitter systems that indirectly compensate for the deficit of cholinergic functions, agents that affect the process of the formation of neurofibrillary tangles, anti-inflammatory agents that prevent the negative response of nerve cells to the pathological process. The goal of the present review is the validation and an analysis from the point of view of medicinal chemistry of the principles of the directed search of drugs for the treatment and prevention of AD and related neurodegenerative disorders. It is based on systematization of the data on biochemical and structural similarities in the interaction between physiologically active compounds and their biological targets related to the development of such pathologies. The main emphasis is on cholinomimetic, anti-amyloid and anti-metabolic agents, using the data that were published during the last 3 to 4 years, as well as the results of clinical trials presented on corresponding websites. © 2002 Wiley Periodicals, Inc. Med Res Rev, 23, No. 1, 48,88, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/med.10026 [source] Chemically Directed Assembling of Functionalized Luminescent Nanocrystals onto Plasma Modified Substrates Towards Sensing and Optoelectronic ApplicationsPLASMA PROCESSES AND POLYMERS, Issue S1 2009Eloisa Sardella Abstract In this work semiconductor nanocrystals (NCs) were assembled by means of a layer-by-layer procedure, by properly combining RF (13.56,MHz) glow discharge-assisted processes with wet chemistry approaches. Colloidal core shell type NCs formed by CdSe coated with an epitaxial layer of ZnS (CdSe@ZnS) were then assembled, from aqueous solution, onto the plasma modified materials. The obtained results show that spatially resolved NC assembling can be successfully achieved on micro-structured domains obtained by means of plasma assisted processes. Layers of functionalized NCs are thus demonstrated to be materials that can be effectively integrated into devices for application in photovoltaics, electronic nano-devices and biological sensors. [source] Expression, purification, and analysis of unknown translation factors from Escherichia coli: A synthesis approachBIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION, Issue 1 2010Justin D. Walter Abstract New approaches are currently being developed to expose biochemistry and molecular biology undergraduates to a more interactive learning environment. Here, we propose a unique project-based laboratory module, which incorporates exposure to biophysical chemistry approaches to address problems in protein chemistry. Each of the experiments described herein contributes to the stepwise process of isolating, identifying, and analyzing a protein involved in a central biological process, prokaryotic translation. Students are provided with expression plasmids that harbor an unknown translation factor, and it is their charge to complete a series of experiments that will allow them to develop hypotheses for discovering the identity of their unknown (from a list of potential candidates). Subsequent to the identification of their unknown translation factor, a series of protein unfolding exercises are performed employing circular dichroism and fluorescence spectroscopies, allowing students to directly calculate thermodynamic parameters centered around determining the equilibrium constant for unfolding as a function of denaturant (temperature or chemical). The conclusion of this multi-part laboratory exercise consists of both oral and written presentations, emphasizing synthesis of the roles of each translation factor during the stepwise process of translation. [source] | |||||||||||||