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Versatility
Kinds of Versatility Selected AbstractsVersatility of Laser Pyrolysis Applied to the Synthesis of TiO2 Nanoparticles , Application to UV AttenuationEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 6 2008Bruno Pignon Abstract TiO2 nanoparticles show interesting catalytic and optical properties and are therefore highly demanded for several applications. In this paper, we show that pure and N-doped TiO2 powders with an average diameter as low as 8 nm can be synthesized by laser pyrolysis, with the use of an aerosol of TTIP (titanium tetraisopropoxide) as the main precursor sensitized by C2H4. We demonstrate the possibility to control the anatase/rutile phase ratio over a large range, which was not achieved before, by tuning the experimental parameters. N-doped particles have also been produced for the first time by this method by using a one-step process through addition of NH3. First results illustrating the consequences in terms of UV absorption properties are also presented and correlated with the structural evolution and the presence of a doping element.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Utilization of the Versatility of Sulfur in C,C Bond Formation and Cleavage: Synthesis of ABC Taxoid SkeletonsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2007Subhash P. Chavan Abstract A practical and convenient five-step protocol is described to access the ABC ring system of Taxol by utilizing the versatility of the sulfur atom in its various oxidation states viz., condensation/Pummerer cyclization/coupling/annulation/fragmentation. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] On the design of ultrafast shutters for time-resolved synchrotron experimentsJOURNAL OF SYNCHROTRON RADIATION, Issue 1 2007Milan Gembicky A comprehensive treatment of the limitations and possibilities for single-pulse selection in synchrotron operating modes with ,150,ns bunch separation, as occurs in the standard operating mode at the Advanced Photon Source, is presented. It is shown that the strength of available materials and allowable kinetic energy build-up limit single-bunch selection for this separation to sample sizes of ,100,µm, and that for minimization of kinetic energy build-up it is preferable to increase the r.p.m. within physically acceptable limits rather than increase the disc radius to obtain a desirable peripheral speed. A slight modification of the equal-bunch spacing standard fill patterns is proposed that allows use of samples as large as 500,µm. The corresponding peripheral speed of the chopper wheel is ,600,m,s,1, which is within the limits of high-strength titanium alloys. For smaller samples, peripheral speeds are proportionally lower. Versatility can be achieved with interchangeable chopper wheels and the use of different orientations of the rotation axis relative to the X-ray beam, which opens the possibility of larger, rather than one-of-a-kind, production runs. [source] Versatility of vertical rectus abdominis musculocutaneous flapsMICROSURGERY, Issue 5 2006Markus V. Küntscher M.D., Ph.D. The purpose of the study was to demonstrate a variety of indications for the vertical rectus abdominis musculocutaneous (VRAM) flap with respect to donor-site morbidity and alternative procedures. Fifteen VRAM flaps were performed in 15 patients during a 4-year period. The average age of patients was 58 years (range, 34,76 years). Inferiorly based VRAM flaps were used for defect coverage after tumor resection and for penile reconstruction in 7 cases. Superiorly based VRAM flaps were performed in 7 cases for reconstruction of osteocutaneous defects following sternal osteomyelitis and tumor resection. Arterial and venous "supercharging" was necessary in one case. One free VRAM flap was performed in a patient suffering from an osteocutaneous defect after resection of a malignant melanoma metastasis with infiltration of the brain and skull. The reconstructive goals were achieved in all cases using VRAM flap procedures. No total flap loss occurred. Minor complications as well as abdominal wall bulging and hernias were observed in four cases. The pedicled VRAM flap provides a reliable tool for coverage of large soft-tissue defects of the chest wall, groin, hip, and perineum even in a high-risk population, in which a safe and fast forward flap procedure is the primary reconstructive goal. Arterial and/or venous supercharging may be necessary, particularly in superiorly based VRAM flaps. An inferiorly based VRAM flap is a reliable tool for phalloplasty under special circumstances. The indication for free VRAM flaps is given in rare clinical situations. Stabilization of the donor site using artificial mesh is highly recommended. © 2006 Wiley-Liss, Inc. Microsurgery, 2006. [source] Versatility and commitment in muscleTHE JOURNAL OF PHYSIOLOGY, Issue 3 2005Terence Partridge No abstract is available for this article. [source] Designing Morpho-Ecologies: Versatility and Vicissitude of Heterogeneous SpaceARCHITECTURAL DESIGN, Issue 2 2008Michael Hensel Abstract ,Morpho-Ecology' is a concept and design approach that combines the notion of ,morphology', and thus intrinsically ,morphogenesis', with the notion of ,ecology'. In the early 19th century, in the context of his studies in botany, the poet and writer Goethe defined morphology as the study of forms; he combined the study of ,Gestalt', or structured form, with the process of ,Bildung', or formation, which acts continuously upon form.1 Later on in the century, the term ,ecology' was coined by the German physician and zoologist Ernst Haeckel, who defined it as the science of relationships between organisms and their environment.2 Here Michael Hensel and Achim Menges outline their theoretical and methodological framework for ,morpho-ecological design' in architecture, illustrating it further with two projects that combine research and design. Copyright © 2008 John Wiley & Sons, Ltd. [source] ChemInform Abstract: Unique Versatility of Ionic Liquids as Clean Decarboxylation Catalyst Cum Solvent: A Metal- and Quinoline-Free Paradigm Towards Synthesis of Indoles, Styrenes, Stilbenes and Arene Derivatives under Microwave Irradiation in Aqueous Conditions.CHEMINFORM, Issue 19 2009Abhishek Sharma 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] Tandem Nucleophilic Addition/Fragmentation Reactions and Synthetic Versatility of Vinylogous Acyl Triflates.CHEMINFORM, Issue 39 2006Shin Kamijo 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] The Influence of Phosphane Ligands on the Versatility of Ruthenium,Indenylidene Complexes in MetathesisCHEMISTRY - A EUROPEAN JOURNAL, Issue 30 2010Julie Broggi Dr. Abstract The aim of the present study is to develop readily available and stable pre-catalysts that could be easily prepared on large scale from simple starting materials. Based on the hypothesis that substitution of classical PCy3 with phosphanes of varying electron-donating properties could be a straightforward manner to improve catalytic activity, a methodical study dealing with the effect of phosphane fine-tuning in ruthenium,indenylidene catalysts was performed. Challenged to establish how the electronic properties of para -substituted phosphane ligands translate into catalyst activity, the versatile behaviour of these new ruthenium,indenylidene complexes was investigated for a number of metathesis reactions. [source] Metal-Complex Assemblies Constructed from the Flexible Hinge-Like Ligand H2bhnq: Structural Versatility and Dynamic Behavior in the Solid StateCHEMISTRY - A EUROPEAN JOURNAL, Issue 11 2004Koichi Yamada Dr. Abstract Novel metal-complex assemblies constructed from the flexible hinge-like ligand H2bhnq (H2bhnq=2,2,-bi(3-hydroxy-1,4-naphthoquinone)) have been synthesized. The X-ray crystal structures of these compounds reveal that four types of architectures are accessible by variation of the metal ions. In copper(II) compounds 1,3, the chelating bhnq2, ions bridge copper(II) centers to form one-dimensional zigzag chains. The chains of 1,3 are arranged by hydrogen-bonding interactions and stacking interactions to produce porous structures. Cobalt(II) and zinc(II) compounds 4 and 5 form one-dimensional helical chains. In 4 and 5, the crystal packing induces spontaneous resolution of the helical chains with chiral cavities formed perpendicular to the helices. Nickel(II) compounds 6 and 7 form cyclic tetramers. The fourth architecture, a dimer (compound 8), is obtained by the reaction of zinc(II) and bhnq2, in MeOH. In these compounds, changes of the dihedral angles and the metal-coordination mode of the bhnq2, ion induce the structural versatility. The assemblies of the zigzag chains of the copper(II) compounds exhibit reversible vapochromic behavior. UV/Vis, powder X-ray diffraction, EPR, and adsorption isotherm measurements indicate that this vapochromic behavior is based on the hinge-like flexibility of the bhnq2, ion. [source] Deformation Transfer to Multi-Component ObjectsCOMPUTER GRAPHICS FORUM, Issue 2 2010Kun Zhou Abstract We present a simple and effective algorithm to transfer deformation between surface meshes with multiple components. The algorithm automatically computes spatial relationships between components of the target object, builds correspondences between source and target, and finally transfers deformation of the source onto the target while preserving cohesion between the target's components. We demonstrate the versatility of our approach on various complex models. [source] Sequence alignment on the Cray MTA-2,CONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 9 2004Shahid H. Bokhari Abstract Several variants of standard algorithms for DNA sequence alignment have been implemented on the Cray Multithreaded Architecture-2 (MTA-2). We describe the architecture of the MTA-2 and discuss how its hardware and software enable efficient implementation of parallel algorithms with little or no regard for issues of partitioning, mapping or scheduling. We describe how we ported variants of the naive algorithm for exact alignment and the dynamic programming algorithm for approximate alignment to the MTA-2 and provide detailed performance measurements. It is shown that, for the dynamic programming algorithm, the use of the MTA's ,Full/Empty' synchronization bits leads to almost perfect speedup for large problems on one to eight processors. These results illustrate the versatility of the MTA's architecture and demonstrate its potential for providing a high-productivity platform for parallel processing. Copyright © 2004 John Wiley & Sons, Ltd. [source] Delinquency and the profile of offences among depressed and non-depressed adolescentsCRIMINAL BEHAVIOUR AND MENTAL HEALTH, Issue 2 2006MINNA RITAKALLIO Background,Depression has previously been found to be closely connected to adolescent delinquency, but little is known about how depression is related to different types of delinquency. Aim,To investigate patterns of criminal behaviour according to depression among repeatedly delinquent adolescents. Method,The sample was 14- to 16-year-old repeatedly delinquent adolescents (n 3679) taking part in the Finnish School Health Promotion Study, surveyed for versatility and specialization of delinquency in relation to depression. Results,Patterns of criminal behaviour differed between depressed and non-depressed delinquent adolescents. The delinquent behaviour of depressed adolescents was more versatile than that of non-depressed adolescents who mainly specialized in one offence type. Non-depressed delinquent boys had most often specialized in violence. Most depressed delinquent boys had committed a variety of offences, but among those who did specialize the specialist category was violent offences. Non-depressed delinquent girls had specialized in shoplifting. Among depressed delinquent girls vandalism was the most typical offence. Conclusion,Differences in the delinquent behaviour of depressed and non-depressed delinquent adolescents suggest the value of including clinical assessment, and treatment for some, in an appropriately comprehensive pattern of management. Copyright © 2006 John Wiley & Sons, Ltd. [source] The Versatility of the Nasolabial Flap Enhanced by the Delay ProcedureDERMATOLOGIC SURGERY, Issue 2 2001Isaac Zilinsky MD Background. The nasolabial flap is a versatile and effective option for the closure of nasal defects of the cheek and nasal sidewall following Mohs surgery. However, both extirpation of a tumor in the region of the base of the flap or previous use of the flap often destroy the proximal axial blood supply to the flap, excluding its immediate utilization. We describe a different use of the nasolabial flap and a technique for preserving its capacity in the case of reutilization Objective. To describe the versatility of the nasolabial flap and a delay procedure that enables its exploitation despite prior disruption of the proximal blood supply. Methods. Three different uses of the same nasolabial flap are demonstrated in one patient. The surgical techniques are discussed in detail. Results. The reconstructive results were excellent. There were no postoperative complications. Conclusion. The nasolabial flap is a versatile and effective option for the closure of nasal defects of the cheek and nasal sidewall. When the nasolabial flap has been used before, or its blood supply compromised, the delay procedure can reestablish its applicability. [source] Manipulating gene activity in Wnt1-expressing precursors of neural epithelial and neural crest cellsDEVELOPMENTAL DYNAMICS, Issue 1 2010Wei Hsu Abstract Targeted gene disruption or expression often encounters lethality. Conditional approaches, permitting manipulation at desired stages, are required to overcome this problem in order to analyze gene function in later developmental processes. Wnt1 has been shown to be expressed in neural crest precursors at the dorsal midline region. However, its expression was not detected in emigrated neural crest cells, the descendants of Wnt1-expressing precursors. We have developed mouse transgenic systems to manipulate gene activity in the Wnt1-expressing precursors and their derivatives by integrating the tetracycline-dependent activation and Cre-mediated recombination methods. A new Wnt1-rtTA strain, carrying rtTA under control of Wnt1 regulatory elements, has been created for gene manipulation in a spatiotemporal-specific fashion. Together with our previously developed Wnt1-Cre;R26STOPrtTA model, these systems permit conditional gene expression and ablation in pre-migratory and/or post-migratory neural crest cells. This study demonstrated the versatility of our mouse models to achieve gene manipulation in early neural development. Developmental Dynamics 239:338,345, 2010. © 2009 Wiley-Liss, Inc. [source] Lost zooplanktivorous cichlid from Lake Victoria reappears with a new tradeECOLOGY OF FRESHWATER FISH, Issue 4 2003E. F. B. Katunzi Abstract,,, The zooplanktivorous cichlid Haplochromis pyrrhocephalus, which was one of the most common haplochromine species in the Mwanza Gulf of Lake Victoria, had almost completely disappeared after the Nile perch upsurge in the 1980s. In the second half of the 1990s, this species suddenly reappeared in the strongly changed ecosystem. Gut content investigation revealed a change in diet. Currently, H. pyrrhocephalus eats large prey more frequently than in the past. These large prey comprise fish, shrimps and molluscs. The latter two were never encountered in specimens from the past. Particularly feeding on molluscs was unexpected, as it had been suggested that, because of anatomical constraints, molluscivory and zooplanktivory are incompatible in cichlid fish. Our observations provide a new example of the extreme versatility in feeding behaviour in haplochromine cichlids. [source] Amperometric Detection of 4-Chlorophenol on Two Types of Expanded Graphite Based Composite ElectrodesELECTROANALYSIS, Issue 22 2008Aniela Pop Abstract The assessment of an expanded graphite-Ag-zeolite-epoxy composite (EG-Z-Ag-Epoxy) electrode for the determination of 4-chlorophenol (4-CP) is described and compared to the corresponding expanded graphite-epoxy composite (EG-Epoxy) electrode. Cyclic voltammetry was used to characterize the electrochemical behavior and determination of 4-CP at both electrodes in 0.1,M Na2SO4 and 0.1,M NaOH supporting electrolytes. A substantial enhancement of sensitivity for the determination of 4-CP at the EG-Z-Ag-Epoxy electrode was reached by applying a chemical preconcentration step prior to voltammetric quantification. Also, under these last conditions the lowest limit of detection of 1,,M illustrates the analytical versatility of this electrode in a concentration range where aquatic 4-chlorophenol pollution is known to occur. [source] Electroanalytical Approach to Evaluate Antioxidant Capacity in Honeys: Proposal of an Antioxidant IndexELECTROANALYSIS, Issue 18 2006Mónica Ávila Abstract A novel electrochemical route to estimate the antioxidant capacity in honey samples is proposed just using flow injection analysis. The analytical strategy involved the selective oxidation of polyphenolic compounds using two different target potentials, +0.8 and +0.5,V, at two different pHs. An oxidation current obtained at the fixed potential was used as an analytical guide of the antioxidant activity of the target honeys. Chemometrics (correlation and principal component analysis, PCA) demonstrated the significance of the electrochemical protocol versus the traditional spectrophotometric ones in the evaluation of antioxidant capacity and revealed the role of detection potential as a screening variable. The proposed protocol is very simple and fast. However, the most relevant merit of the electrochemical procedure is its inherent versatility which allows the evaluation of the antioxidant activity under predesigned controlled oxidation conditions. In addition, since intercept was statistically zero, its corresponding antioxidant content using just a calibration factor is proposed thus simplifying the calibration-analysis process. As a result, an electrochemical antioxidant index (EAI) is proposed. [source] Electrochemical Approach to the Radical Anion Formation from 2,-Hydroxy Chalcone DerivativesELECTROANALYSIS, Issue 5 2006P. Quintana-Espinoza Abstract Three 2,-hydroxy chalcone derivatives were electrochemically reduced to the radical anion by a reversible one-electron transfer followed by a chemical dimerization reaction. Under suitable conditions of the medium, the one-electron reduction produces very well resolved cyclic voltammograms due to the formation of the radical anion. By using appropriately the wide versatility of the cyclic voltammetric technique, was possible to study the generation of the radical anion and its stability. [source] Coupling Capillary Electrophoresis and Pulsed Electrochemical DetectionELECTROANALYSIS, Issue 13 2005Carlos Abstract Pulsed electrochemical detection (PED) is an excellent method for detection of analytes that normally foul electrodes. In PED, the detection electrode is first cleaned at a high positive potential, then reactivated at a negative potential dissolving the surface oxide, and finally used to oxidize the analyte at a moderate positive potential. Due to the advantages and versatility of PED, many different variations of the detection waveform can be found in literature. This review focuses on application of PED to CE and in particular, the most commonly used modes: pulsed amperometric detection (PAD) and integrated pulsed amperometric detection (iPAD). [source] Achiral and chiral separations using MEKC, polyelectrolyte multilayer coatings, and mixed mode separation techniques with molecular micellesELECTROPHORESIS, Issue 6 2010Candace A. Luces Abstract Mixed mode (MM) separation using a combination of MEKC and polyelectrolyte multilayer (PEM) coatings is herein reported for the separation of achiral and chiral analytes. Many analytes are difficult to separate by MEKC and PEM coatings alone. Therefore, the implementation of a MM separation provides several advantages for overcoming the limitations of these well-established methods. In this study, it was observed that achiral separations using MEKC and PEM coatings individually resulted in partial resolution of eight very similar aryl ketones when the molecular micelle (sodium poly(N -undecanoyl- L -glycinate)) concentration was varied from 0.25 to 1.00%,w/v and the bilayer number varied from 2 to 4. However, when MM separation was introduced, baseline resolution was achieved for all eight analytes. In the case of chiral separations, temazepam, aminoglutethimide, benzoin, benzoin methyl ether, and coumachlor were separated using the three separation techniques. For chiral separations, the chiral molecular micelle, sodium poly(N -undecanoyl- L -leucylvalinate), was employed at concentrations of 0.25,1.50%,w/v for both MEKC and PEM coatings. Overall, the results revealed partial separation with MEKC and PEM coatings individually. However, MM separation enabled baseline separation of each chiral mixture. The separation of achiral and chiral compounds from different compound classes demonstrates the versatility of this MM approach. [source] Integrated microdevice for preconcentration and separation of a wide variety of compounds by electrochromatographyELECTROPHORESIS, Issue 3 2009Gaelle Proczek Abstract An integrated microdevice was developed to couple on-chip SPE to separation by channel electrochromatography. An acrylate-based monolith was synthesized within a glass microdevice by photoinitiated polymerization. It was used for both separation and preconcentration by direct injection on the head of the stationary phase or by confining the preconcentration step in a given zone of the stationary phase. The composition of the polymerization mixture was chosen to achieve a monolithic material containing both hydrophobic and charged moieties to ensure an electroosmotic flow for separation. As a consequence the extraction procedure occurs via hydrophobic and ionic interactions. Neutral, ionizable and charged compounds were successfully preconcentrated and separated within the microdevice through electrochromatographic mechanisms, highlighting the versatility of this device. The performance of the integrated microdevice was demonstrated with the preconcentration and separation of a mixture of PAHs for which a signal enhancement factor (SEF) of 270 was achieved within 120,s of preconcentration. In the case of charged and ionizable compounds, according to the electrolyte composition, contributions of both reverse-phase and ion-exchange mechanisms were used to perform effective electrochromatographic preconcentration. A SEF of 250 was obtained for the model-charged compound within 20,s of preconcentration. Finally, the potentials of on-chip preconcentrate and separate both neutral and ionized compounds have been demonstrated using a mixture of model compounds. [source] Recent advances in enhancing the sensitivity of electrophoresis and electrochromatography in capillaries and microchips (2006,2008)ELECTROPHORESIS, Issue 1 2009Michael C. Breadmore Abstract Poor sensitivity is still considered to be one of the major limitations of electrophoresis, which is surprising given the power, flexibility and versatility of many of the approaches to on-line concentration that have developed over the last 20 years. This is still a very active area of interest and this review will cover developments in the field over the last two years since the last review (Electrophoresis 2007, 28, 254,281) through to June 2008. It includes developments in the fields of stacking, covering all methods from field-amplified sample stacking and large volume sample stacking, through to ITP, dynamic pH junction and sweeping. Attention is also given to on-line or in-line extraction methods that have been used for electrophoresis. [source] CE frontal analysis based on simultaneous UV and contactless conductivity detection: A general setup for studying noncovalent interactionsELECTROPHORESIS, Issue 3 2007Henrik Jensen Dr. Abstract CE frontal analysis (CE-FA) has been established as a powerful tool to study noncovalent interactions between macromolecules and small molecules such as drug substances or pharmaceutical excipients. However, when using traditional commercial CE instrumentation, a serious drawback is related to the fact that only UV-active compounds can be studied. In recent years, contactless conductivity detection has become an attractive alternative to UV detection in CE due to its high versatility. In this study, we combine contactless conductivity detection and UV detection in a highly versatile setup for profiling noncovalent interactions between low-molecular-weight molecules and macromolecules. In the case of molecules having a chromophore the setup allows determination of binding constants using two independent detectors. The new contactless conductivity detection cell is compatible with commercial CE instrumentation and is therefore easily implemented in any analysis laboratory with CE expertise. [source] Micro freef-low IEF enhanced by active cooling and functionalized gelsELECTROPHORESIS, Issue 24 2006Jacob W. Albrecht Abstract Rapid free-flow IEF is achieved in a microfluidic device by separating the electrodes from the focusing region with porous buffer regions. Moving the electrodes outside enables the use of large electric fields without the detrimental effects of bubble formation in the active region. The anode and cathode porous buffer regions, which are formed by acrylamide functionalized with immobilized pH groups, allow ion transport while providing buffering capacity. Thermoelectric cooling mitigates the effects of Joule heating on sample focusing at high field strengths (,500,V/cm). This localized cooling was observed to increase device performance. Rapid focusing of low-molecular-weight pI markers and Protein G,mouse IgG complexes demonstrate the versatility of the technique. Simulations provide insight into and predict device performance based on a well-defined sample composition. [source] Electrophoretically mediated microanalysis with partial filling technique and indirect or direct detection as a tool for inhibition studies of enzymatic reactionELECTROPHORESIS, Issue 7-8 2004Magdaléna Telnarová Abstract The inhibition of the model enzyme, haloalkane dehalogenase from Sphingomonas paucimobilis, was investigated by a combination of electrophoretically mediated microanalysis with a partial filling technique, followed by indirect or direct detection. In this setup, part of the capillary is filled with a buffer suitable for the enzymatic reaction (20 mM glycine buffer, pH 8.6) whereas the rest of the capillary is filled with the background electrolyte optimal for separation of substrates and products. Two different background electrolytes and corresponding detection approaches were used to show the versatility of the developed method. The inhibition effect of 1,2-dichloroethane on the dehalogenation of brominated substrate 1-bromobutane was studied by means of 10 mM chromate , 0.1 mM cetyltrimethylammonium bromide (pH 9.2) in combination with indirect detection or 20 mM ,-alanine , hydrochloric acid (pH 3.5) in combination with direct detection. The method was used to estimate the inhibition constant KI (0.44 mM by indirect detection and 0.63 mM by of direct detection) and to determine the inhibition type. Compared to spectrophotometric and other discontinuous assays, the method is rapid, can be automated, and requires only small amount of reagents that is especially important in the case of enzymes and inhibitors. [source] Molecular characterization of sulfate-reducing bacteria in a New England salt marshENVIRONMENTAL MICROBIOLOGY, Issue 8 2005Michele Bahr Summary Sulfate reduction, mediated by sulfate-reducing bacteria (SRB), is the dominant remineralization pathway in sediments of New England salt marshes. High sulfate reduction rates are associated with the rhizosphere of Spartina alterniflora when plants elongate aboveground. The growth process concurrently produces significant amounts of new rhizome material belowground and the plants leak dissolved organic compounds. This study investigated the diversity of SRB in a salt marsh over an annual growth cycle of S. alterniflora by exploring the diversity of a functional gene, dissimilatory sulfite reductase (dsrAB). Because the dsrAB gene is a key gene in the anaerobic sulfate-respiration pathway, it allows the identification of microorganisms responsible for sulfate reduction. Conserved dsrAB primers in polymerase chain reaction (PCR) generated full-length dsrAB amplicons for cloning and DNA sequence analysis. Nearly 80% of 380 clone sequences were similar to genes from Desulfosarcina and Desulfobacterium species within Desulfobacteraceae. This reinforces the hypothesis that complete oxidizers with high substrate versatility dominate the marsh. However, the phylotypes formed several clades that were distinct from cultured representatives, indicating a greater diversity of SRB than previously appreciated. Several dsrAB sequences were related to homologues from Gram-positive, thermophilic and non-thermophilic Desulfotomaculum species. One dsrAB lineage formed a sister group to cultured members of the delta-proteobacterial group Syntrophobacteraceae. A deeply branching dsrAB lineage was not affiliated with genes from any cultured SRB. The sequence data from this study will allow for the design of probes or primers that can quantitatively assess the diverse range of sulfate reducers present in the environment. [source] Quorum sensing: the power of cooperation in the world of PseudomonasENVIRONMENTAL MICROBIOLOGY, Issue 4 2005Mario Juhas Summary Work over the past few years has provided evidence that quorum sensing is a generic regulatory mechanism that allows bacteria to launch a unified, coordinated response in a population density-dependent manner to accomplish tasks which would be difficult, if not impossible, to achieve for a single bacterial cell. Quorum sensing systems are widespread among pseudomonads and the one of the human opportunistic pathogen Pseudomonas aeruginosa belongs to the most extensively studied cell-to-cell communication systems. In this organism, quorum sensing is highly complex and is made up of two interlinked N- acyl homoserine lactone (AHL)-dependent regulatory circuits, which are further modulated by a non-AHL-related signal molecule and numerous regulators acting both at the transcriptional and post-transcriptional level. This genetic complexity may be one of the key elements responsible for the tremendous environmental versatility of P. aeruginosa. Work of the past few years showed that quorum sensing is essential for the expression of a battery of virulence factors as well as for biofilm formation in P. aeruginosa and thus represents an attractive target for the design of novel drugs for the treatment of P. aeruginosa infections. Furthermore, the cell-to-cell communication ability was also demonstrated in a number of additional pseudomonads. [source] Novel Synthetic Strategy towards the Efficient Synthesis of Substituted Bis(pyrazolyl)(2-pyridyl)methane Ligands,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 21 2010Alexander Hoffmann Abstract A general one-pot synthesis of new substituted heteroscorpionate ligands is presented. These mixed-functionality ligands were obtained in a catalyzed Peterson rearrangement starting from the substituted pyrazole, thionyl chloride, and an aldehyde. Thus, the synthesis of polyfunctional tridentate ligands is enabled, and they contain, besides the two pyrazole groups, other functionalities relevant for coordination chemistry. Additionally, the steric hindrance is easily defined in the ligands by the substitution of the pyrazole rings. By combination of the versatility in donor function and steric demand, a systematic tuning of the properties of the bis(pyrazolyl)methane ligands is possible. The synthesis and full characterization of 11 bis(pyrazolyl)methane ligands are reported. Two of these were structurally characterized as well. [source] Cobalt-Catalyzed C,N Bond-Forming Reaction between N-Aromatic 2-Chlorides and Secondary AminesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 27 2009Gabriel Toma Abstract Secondary amines react with N-aromatic 2-chlorides in the presence of a catalytic amount of cobalt chloride. When DPPP was added as ligand, the yield was further improved. The N-aromatic-containing tertiary amines formed are interesting due to their potential biological activity. This work represents the first cobalt-catalyzed approach to C,N bond formation involving N-aromatic 2-chlorides and secondary amines having a certain amount of versatility and functional group tolerance.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] | |||||||||||||||||||||||||||||||||||||||||||||||||