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Minireview
Selected AbstractsMINIREVIEW: On the use of metaphor to understand, explain, or rationalize redundant genes in yeastFEMS YEAST RESEARCH, Issue 3 2008Stephen Cooper Abstract The proposal that yeast, and cells in general, contains redundant genes that enable cells to survive mutational change has been supported by experiments and a strong metaphor. The redundant gene proposal is analyzed, and it is noted that there are many problems with the redundant gene model. An alternative metaphor is suggested to explain the genetic composition of a yeast culture. [source] Adherence factors of Lactobacillus in the human gastrointestinal tractFEMS MICROBIOLOGY LETTERS, Issue 2 2007Mónica Perea Vélez Abstract Despite the increasing number of scientific reports describing adhesion of Lactobacillus to components of the human intestinal mucosa, information on the surface molecules mediating this adhesion and their corresponding receptors is fragmentary. This MiniReview compiles present knowledge of the genetically and functionally characterized Lactobacillus factors responsible for mediating adhesion to different components of the human gastrointestinal tract. In addition, for the proteins among these factors, the domain structure is discussed, and where appropriate the results of in silico analyses are reported. [source] ,-Synuclein, oxidative stress and apoptosis from the perspective of a yeast model of Parkinson's diseaseFEMS YEAST RESEARCH, Issue 8 2006Stephan N. Witt Abstract The neuronal protein ,-synuclein (,-syn) has been suggested to be one of the factors linked to Parkinson's disease (PD). Several organisms, including the rat, mouse, worm, and fruit fly, are being used to study ,-syn pathobiology. A new model organism was recently added to this armamentarium: the budding yeast Saccharomyces cerevisiae. The yeast system recapitulates many of the findings made with higher eukaryotes. For example, yeast cells expressing ,-syn accumulate lipid droplets, have vacuolar/lysosomal defects, and exhibit markers of apoptosis, including the externalization of phosphatidylserine, the release of cytochrome c, and the accumulation of reactive oxygen species. This MiniReview focuses on the mechanisms by which ,-syn induces oxidative stress and the mechanisms by which yeast cells respond to this stress. Three classes of therapeutics are discussed. [source] Mechanisms of cytochrome P450 substrate oxidation: MiniReviewJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 4 2007F. Peter Guengerich Abstract Cytochrome P450 (P450) enzymes catalyze a variety of oxidation and some reduction reactions, collectively involving thousands of substrates. A general chemical mechanism can be used to rationalize most of the oxidations and involves a perfenyl intermediate (FeO3+) and odd-electron chemistry, i.e. abstraction of a hydrogen atom or electron followed by oxygen rebound and sometimes rearrangement. This general mechanism can explain carbon hydroxylation, heteroatom oxygenation and dealkylation, epoxidation, desaturation, heme destruction, and other reactions. Another approach to understanding catalysis involves analysis of the more general catalytic cycle, including substrate specificity, because complex patterns of cooperativity are observed with several P450s. Some of the complexity is due to slow conformational changes in the proteins that occur on the same timescale as other steps. © 2007 Wiley Periodicals, Inc. J Biochem Mol Toxicol 21:163,168, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20174 [source] Amelioration of Oxaliplatin Neurotoxicity by Drugs in Humans and Experimental Animals: A MiniReview of Recent LiteratureBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 4 2010Badreldin H. Ali The drug is particularly useful alone and in combination with flurouracil and leucovorin in colorectal cancer, but it is also used for other cancers such as those of the ovary, lung, breast and liver, as well as non-Hodgkin's lymphoma. The drug is known to cause neurological, gastrointestinal and haematological toxicities. Neurotoxicity occurs in most of the treated patients and is considered to be a serious limitation for the use of the drug. The mechanism of the neurotoxicity is not known with certainty but may involve prolongation of sodium channels opening. Strategies to ameliorate oxaliplatin neurotoxicity include the use of several ,neuroprotective' drugs. This MiniReview attempts to list and comment on the action and use of some of these agents, which include carbamazepine, gabapentin, calcium and magnesium salts, reduced glutathione, N -acetylcysteine and a few others. None of these drugs have been proven to be effective in large, controlled, clinical trials. [source] The Effect of Aromatase Inhibitors on Bone MetabolismBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 1 2009Lars Folkestad Aromatase is a cytochrome P450 enzyme complex catalysing the conversion of androgens to oestrogens. These properties cause a significant increase in bone loss. In this MiniReview, we present data from the aromatase inhibitor studies and the studies designed to investigate aromatase inhibitor effect on bone metabolism. At the cellular level, oestrogen has profound effects on both osteoblasts and osteoclasts. Oestrogen decreases the osteoblastic production of resorptive cytokines and simultaneously increases the production of antireceptive cytokines, which leads to increased osteoclastic apoptosis and increased osteoblastic activity. Aromatase inhibitors inhibit the endogenous production of oestrogen by 50,90%. Studies designed to look at the effect of aromatase inhibitors on bone mineral density have shown a significant decrease in bone mineral density of the femoral neck in the aromatase inhibitor groups compared to placebo groups. Placebo-controlled studies lack statistical power to detect changes in fracture incidence; however, aromatase inhibitors increase the incidence of fractures in comparison with tamoxifen. We conclude that treatment with aromatase inhibitors leads to an increased bone loss and thus an increase in the risk of fractures in women with breast cancer. [source] Is Metformin Therapy for Polycystic Ovary Syndrome Safe During Pregnancy?BASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 6 2005Birgitte Brock Due to its positive effects on polycystic ovary syndrome-induced infertility metformin has become one of the most common drugs used in this group of patients. The efficacy of the drug as well as the first reports on metformin used in pregnancy has encouraged the continued use of the drug after conception. This MiniReview reviews the current pros and cons of metformin use in pregnancy while awaiting the results of ongoing randomised, controlled clinical trials addressing the subject. [source] Minireview: On the homology of the protocoel in Cephalochordata and ,lower' DeuterostomiaACTA ZOOLOGICA, Issue 1 2002Thomas Stach Abstract Hypotheses regarding the homology of the protocoel in planktonic deuterostome larvae and mesodermal structures in ontogenetic stages of cephalochordates are evaluated. The prevalent ,classical' hypothesis describes the protocoel as being homologous with the diverticula of Hatschek, which, on the left side, develop into the preoral pit, subsequently into Hatschek's pit and groove (in part). This hypothesis is based mainly on the position of Hatschek's diverticula anterior to the rest of the mesoderm during their enterocoelic origin. It is shown here that during development the mesodermal segment that develops into Hatschek's nephridium is the most anterior one prior to formation of Hatschek's diverticula, and this segment assumes an anteriormost position after differentiation of Hatschek's diverticula. Additional similarities between this segment and protocoels are: (i) presence of endomesodermal cells with podocytic extensions, (ii) excretory function, (iii) relatively early ontogenetic origin, (iv) probable lack of association with nervous structures, (v) probable ectodermal origin of a portion of the canal, and (vi) position relative to the mouth opening. Therefore, homology between the protocoel and the segment that becomes Hatschek's nephridium is proposed. It is concluded that a glandular structure homologous to the diverticula of Hatschek and anterior to the protocoel/Hatschek's nephridium is a synapomorphy of notochordates or chordates. [source] Listeria monocytogenes: epidemiology, human disease, and mechanisms of brain invasionFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 2 2008Douglas A. Drevets Abstract Listeria monocytogenes is a facultative intracellular bacterium that has predilection for causing central nervous systemic infections in humans and domesticated animals. This pathogen can be found worldwide in the food supply and most L. monocytogenes infections are acquired through ingestion of contaminated food. The main clinical syndromes caused by L. monocytogenes include febrile gastroenteritis, perinatal infection, and systemic infections marked by central nervous system infections with or without bacteremia. Experimental infection of mice has been used for over 50 years as a model system to study the pathogenesis of this organism including the mechanisms by which it invades the brain. Data from this model indicate that a specific subset of monocytes, distinguished in part by high expression of the Ly-6C antigen, become parasitized in the bone marrow and have a key role in transporting intracellular bacteria across the blood-brain barriers and into the central nervous system. This Minireview will summarize recent epidemiologic and clinical information regarding L. monocytogenes as a human pathogen and will discuss current in vitro and in vivo data relevant to the role of parasitized monocytes and the pathogenetic mechanisms that underlie its formidable ability to invade the central nervous system. [source] Minireview: does in-vitro testing of oximes help predict their in-vivo action after paraoxon exposure?JOURNAL OF APPLIED TOXICOLOGY, Issue 6 2009D. E. Lorke Abstract K-oximes have recently been developed in the search for efficacious broad-band reactivators of acetylcholinesterase (AChE) inhibited by organophosphorus compounds (OPC). Before clinical use, their toxicity and efficacy need to be assessed, and there is clear demand for simple in vitro tests that can predict in vivo performance. This article summarizes our in vitro data obtained for conventional and experimental oximes in human and rat blood exposed to the OPC paraoxon and correlates them with our in vivo results. The intrinsic AChE inhibitory activity of oximes, as reflected by their in vitro IC50, is strongly correlated with their LD50 (rat): oximes with a high IC50 (K-27, K-48, pralidoxime and obidoxime) also show a high LD50 and are thus relatively non-toxic, whereas oximes K-105, K-108 and K-113 have a low IC50, a low LD50 and are far more toxic. The IC50 is also correlated with the in vivo capacity to protect from paraoxon-induced mortality: oximes with a higher IC50 reduce the relative risk of death more. In contrast, the protective ability as assessed in vitro by the slope of the IC50 shift (tan,), is not correlated with in vivo protection from paraoxon-induced mortality: the best in vivo protectors (K-27 and K-48) show a much lower tan, value (around 2) than K-110 and K-113 (tan, around 10), which hardly reduce the relative risk of death after paraoxon exposure. The partition coefficient logP of the individual oximes is inversely correlated with their IC50 and with their LD50 and is therefore an indicator of toxicity: strongly hydrophilic oximes tend to be less toxic than less hydrophilic ones. These data highlight the good predictive value of in vitro IC50 testing for in vivo toxicity and the limited practical significance of in vitro assessment of protective potency. Copyright © 2009 John Wiley & Sons, Ltd. [source] General pharmaceutics,The new physical pharmacyJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 7 2003E. F. "Gene" Fiese Abstract General Pharmaceutics is proposed as the broad study of the biopharmaceutical and physical chemical properties of each potential drug substance. When the first quality bulk lot is delivered, usually the first GMP bulk lot, an extensive profiling of the potential drug substance should commence. This profile should include solid-state characterization as well as thorough analyses of solubility, stability, and absorption properties of the drug substance that could affect the development of a viable medicine. As a result of these studies, a number of initial specifications could be developed: the preferred polymorphic or crystalline form identified, the preferred particle size to optimize absorption/development, and an initial biopharmaceutics classification with a dose limit to identify those cases in which the formulation can be expected to improve absorption and exposure. The broad topic of General Pharmaceutics is discussed in this Minireview including many advances in technology in this field as well as the rationale behind the proposed initial specifications. © 2003 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 92:1331,1342, 2003 [source] Minireview: Malassezia infections in immunocompromised patientsMYCOSES, Issue 3 2010Athanasios Tragiannidis Summary Malassezia spp. form part of the normal human cutaneous flora and are implicated in several mild, but recurrent cutaneous diseases, such as pityriasis versicolor, Malassezia folliculitis, seborrhoeic dermatitis, and, with lesser frequency, a range of other dermatological disorders. Malassezia spp. have also been associated with cutaneous and systemic diseases in immunocompromised patients including folliculitis, seborrhoeic dermatitis, catheter-related fungaemia and a variety of deeply invasive infections. In this review, we provide an overview of the epidemiology, risk factors, pathogenesis, clinical manifestations, diagnosis, treatment and outcome of cutaneous and invasive Malassezia infections in immunocompromised patients. [source] The Enteric Nervous System II: Gastrointestinal FunctionsBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 6 2003Mark Berner Hansen This Minireview is part two of three and describes the role of the enteric nervous system in gastrointestinal functions (motility, exocrine and endocrine secretions, blood flow, and immune processes) in health and some disease states. In this context, the functional importance of the enteric nervous system for food intake, the gall bladder, and pancreas will be addressed. In specific, dysmotility, diarrhoea, constipation, non-occlusive intestinal ischaemia (intestinal angina), inflammation, cholelithiasis, cholecystitis, postcholecystectomy syndrome, and pancreatitis can be treated with neuroactive pharmacological agents. For example, serotonin receptor type four agonists can be used for the treatment of constipation, while nitric oxide synthesis inhibitors can be employed for the treatment of intestinal angina. [source] Damage Detection and Base Flipping in Direct DNA Alkylation RepairCHEMBIOCHEM, Issue 3 2009Cai-Guang Yang Prof. Abstract The foreign lesion: The mechanistic questions for DNA base damage detection by repair proteins are discussed in this Minireview. Repair proteins could either probe and locate a weakened base pair that results from base damage, or passively capture an extrahelical base lesion in the first step of damage searching on double-stranded DNA. How some repair proteins, such as AGT (see figure), locate base lesions in DNA is still not fully understood. To remove a few damaged bases efficiently from the context of the entire genome, the DNA base repair proteins rely on remarkably specific detection mechanisms to locate base lesions. This efficient molecular recognition event inside cells has been extensively studied with various structural and biochemical tools. These studies suggest that DNA base damage can be located by repair proteins by using two mechanisms: a repair protein can probe and detect a weakened base pair that results from mutagenic or cytotoxic base damage; alternatively, a protein can passively capture and stabilize an extrahelical base lesion. Our chemical and structural studies on the direct DNA repair proteins hAGT, C-Ada and ABH2 suggest that these proteins search for weakened base pairs in their first step of damage searching. We have also discovered a very unique base-flipping mechanism used by the DNA repair protein AlkB. This protein distorts DNA and favors single stranded DNA (ssDNA) substrates over double-stranded (dsDNA) ones. Potentially, it locates base lesions in dsDNA by imposing a constraint that targets less rigid regions of the duplex DNA. The exact mechanism of how AlkB and related proteins search for damage in ssDNA and dsDNA still awaits further studies. [source] Design of Gold Nanoparticle-Based Colorimetric Biosensing AssaysCHEMBIOCHEM, Issue 15 2008Weian Zhao Abstract Gold nanoparticle (AuNP)-based colorimetric biosensing assays have recently attracted considerable attention in diagnostic applications due to their simplicity and versatility. This Minireview summarizes recent advances in this field and attempts to provide general guidance on how to design such assays. The key to the AuNP-based colorimetric sensing platform is the control of colloidal AuNP dispersion and aggregation stages by using biological processes (or analytes) of interest. The ability to balance interparticle attractive and repulsive forces, which determine whether AuNPs are stabilized or aggregated and, consequently, the color of the solution, is central in the design of such systems. AuNP aggregation in these assays can be induced by an "interparticle-crosslinking" mechanism in which the enthalpic benefits of interparticle bonding formation overcome interparticle repulsive forces. Alternatively, AuNP aggregation can be guided by the controlled loss of colloidal stability in a "noncrosslinking-aggregation" mechanism. In this case, as a consequence of changes in surface properties, the van der Waals attractive forces overcome interparticle repulsive forces. Using representative examples we illustrate the general strategies that are commonly used to control AuNP aggregation and dispersion in AuNP-based colorimetric assays. Understanding the factors that play important roles in such systems will not only provide guidance in designing AuNP-based colorimetric assays, but also facilitate research that exploits these principles in such areas as nanoassembly, biosciences and colloid and polymer sciences. [source] Recent Advances in Asymmetric Gold CatalysisCHEMCATCHEM, Issue 6 2010Sujata Sengupta Au revoir: Recent years have seen explosive growth in the use of homogeneous gold catalysts, owing to their excellent chemoselectivity, high efficiency, and applicability under mild conditions. In this Minireview, recent progress regarding asymmetric gold catalysis is summarized with discussion focused on homogeneous Au catalysts promoting CC multiple bond activation toward the synthesis of enantiomerically enriched products. [source] Electrochemically Assisted Fabrication of Metal Atomic Wires and Molecular Junctions by MCBJ and STM-BJ Methods,CHEMPHYSCHEM, Issue 13 2010Dr. Jing-Hua Tian Abstract Atomic wires (point contacts) and molecular junctions are two fundamental units in the fields of nanoelectronics and devices. This Minireview introduces our recent approaches aiming to develop versatile methods to fabricate and characterize these unique metallic and molecular structures reliably. Electrochemical methods are coupled with mechanically controllable break junction (EC-MCBJ) or scanning tunneling microscopy (STM) break junction (EC-STMBJ) methods to fabricate metallic point contacts and metal/molecule/metal junctions. With the designed electrodeposition method, the metal of interest (e.g. Au, Cu, Fe or Pd) is deposited in a controlled way on the original electrode pair, on a chip for MCBJ or on the STM tip, to make the metallic contact. Then, various metal atomic wires and molecular junctions can be fabricated and characterized systematically. Herein, we measured the quantized conductance through the construction of histograms of these metal atomic point contacts and of single molecules including benzene-1,4-dithiol (BDT), ferrocene-bisvinylphenylmethyl dithiol (Fc-VPM), 4,4,-bipyridine (BPY), 1,2-di(pyridin-4-yl)ethene (BPY-EE), and 1,2-di(pyridin-4-yl)ethane (BPY-EA). Finally, we briefly discussed the future of EC-MCBJ and EC-STM for nanoelectronics and devices, for example, for the formation of heterogeneous metal-based atomic point contacts and molecular junctions. [source] Primary Photophysical Processes in Photosystem II: Bridging the Gap between Crystal Structure and Optical SpectraCHEMPHYSCHEM, Issue 6 2010Thomas Renger Prof. Dr. Abstract This Minireview summarizes our current knowledge of the optical properties of photosystem II (PS-II) and how these properties are related to the photosynthetic function, that is, excitation energy transfer from the antenna complexes to the reaction center (RC) and the subsequent transmembrane charge separation in the latter. Interpretation of the optical spectra of PS-II is much more difficult than for the RC of purple bacteria, due to the "spectral congestion" problem, namely, the strong spectral overlap of optical bands in PS-II. Recent developments in deciphering the optical properties of the pigments in PS-II, the identification of functional states, and the kinetic details of the primary excitation energy and charge-transfer reactions are summarized. The spectroscopic term P680 that is generally used in the literature no longer indicates the same entity in its cationic and singlet excited form but different subsets of the six innermost pigments of the RC. The accessory chlorophyll ChlD1 forms a sink for singlet excitation and triplet energy and most likely represents the primary electron donor in PS-II. In this respect, a special chlorophyll monomer in PS-II plays the role of the special pair in purple bacteria. Evidence that exciton transfer between the core antenna complexes CP43 and CP47 and the RC is the bottleneck for the overall photochemical trapping of excitation energy in PS-II is discussed. A short summary is provided of PS-II of Acaryochloris marina, which mainly contains chlorophyll d instead of the usual chlorophyll a. This system does not suffer from the spectral congestion problem and, therefore, represents an interesting model system. The final part of this Minireview provides a discussion of challenging problems to be solved in the future. [source] Deforming DNA: From Physics to BiologyCHEMPHYSCHEM, Issue 9-10 2009Chantal Prévost Dr. Abstract DNA molecules do the twist: The DNA double helix is a remarkably adaptable molecule that can undergo major conformational rearrangements without being irreversibly damaged. Indeed, DNA deformation is an intrinsic feature of many biological processes. In this Minireview, the authors summarize recent advances in the study of DNA deformation. The picture shows five different conformations of the double helix of DNA. The DNA double helix has become a modern icon which symbolizes our understanding of the molecular basis of life. It is less widely recognized that the double helix proposed by Watson and Crick more than half a century ago is a remarkably adaptable molecule that can undergo major conformational rearrangements without being irreversibly damaged. Indeed, DNA deformation is an intrinsic feature of many of the biological processes in which it is involved. Over the last two decades, single-molecule experiments coupled with molecular modeling have transformed our understanding of DNA flexibility, while the accumulation of high-resolution structures of DNA,protein complexes have demonstrated how organisms can exploit this property as a useful feature for preserving, reading, replicating, and packaging the genetic message. In this Minireview we summarize the information now available on the extreme,and the less extreme,deformations of the double helix. [source] Mechanical Properties of Carbon NanomaterialsCHEMPHYSCHEM, Issue 7 2007Takuya Hayashi Prof. Abstract Carbon nanomaterials show a variety of interesting chemical and physical properties. In this Minireview we focus on the mechanical properties of carbon nanomaterilas with emphasis on carbon nanotubes and their composite materials. We introduce some recently developed components made of carbon nanotube composite materials and outline their importance for applications in everyday life. [source] Electrochemical Microstructuring with Short Voltage PulsesCHEMPHYSCHEM, Issue 1 2007Rolf Schuster Prof. Dr. Abstract The application of short (nanosecond) voltage pulses between a tool electrode and a workpiece immersed in an electrolyte solution allows the three-dimensional machining of electrochemically active materials with submicrometer resolution. The method is based on the finite charging time constant of the double-layer capacitance, which varies approximately linearly with the local separation between the electrode surfaces. Hence, the polarization of the electrodes during short pulses and subsequent electrochemical reactions are confined to regions where the electrodes are in sufficiently close proximity. This Minireview describes the principles behind electrochemical microstructuring with short voltage pulses, and its current achievements and limitations. [source] The Use of Natural Materials in Nanocarbon SynthesisCHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 11 2009Dang Sheng Su Dr. Abstract Nanomaterials are shifting from laboratory-scale preparation to industrial production. The energy costs and starting materials (feedstock, catalyst, and support) consumed or used in the mass production of nanomaterials are issues that limit their broad application. Natural materials, such as sand, rock, and lava, contain small or trace amounts of metals or metal oxides of nanometer-scale sizes and have been recently used as catalysts for the production of carbon nanotubes (CNTs), providing an interesting way to lower the production cost of CNTs. However, the sustainability of the whole production process still needs to be explored. Layered minerals (e.g., clays) are used to produce CNT,clay hybrids, which can be further used to synthesize polymer,CNT,clay nanocomposites. Natural materials and some byproducts of industrial production processes have been explored as carbon sources for nanocarbon synthesis. This Minireview highlights some recent promising work and prospects for the use of natural materials in the synthesis of CNTs, carbon nanofibers (CNFs), and nanocomposites, and their applications in catalysis and in materials science. [source] Water Splitting on Semiconductor Catalysts under Visible-Light IrradiationCHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 6 2009Rufino Abstract Splitting image: Sustainable hydrogen production is a key target for the development of alternative, future energy systems that will provide a clean and affordable energy supply. This Minireview focuses on the development of semiconductor catalysts that enable hydrogen production via water splitting upon visible-light irradiation. Sustainable hydrogen production is a key target for the development of alternative, future energy systems that will provide a clean and affordable energy supply. The Sun is a source of silent and precious energy that is distributed fairly all over the Earth daily. However, its tremendous potential as a clean, safe, and economical energy source cannot be exploited unless the energy is accumulated or converted into more useful forms. The conversion of solar energy into hydrogen via the water-splitting process, assisted by photo-semiconductor catalysts, is one of the most promising technologies for the future because large quantities of hydrogen can potentially be generated in a clean and sustainable manner. This Minireview provides an overview of the principles, approaches, and research progress on solar hydrogen production via the water-splitting reaction on photo-semiconductor catalysts. It presents a survey of the advances made over the last decades in the development of catalysts for photochemical water splitting under visible-light irradiation. The Minireview also analyzes the energy requirements and main factors that determine the activity of photocatalysts in the conversion of water into hydrogen and oxygen using sunlight. Remarkable progress has been made since the pioneering work by Fujishima and Honda in 1972, but he development of photocatalysts with improved efficiencies for hydrogen production from water using solar energy still faces major challenges. Research strategies and approaches adopted in the search for active and efficient photocatalysts, for example through new materials and synthesis methods, are presented and analyzed. [source] Environmentally Benign Production of Biodiesel Using Heterogeneous CatalystsCHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 2 2009Michikazu Hara, Prof. Abstract Fuelling the future: The production of esters of higher fatty acids from plant materials is of great interest for the manufacture of biodiesel. Heterogeneous catalysts can provide new routes for the environmentally benign production of biodiesel. Particulate heterogeneous catalysts can be readily separated from products following reaction allowing the catalyst to be reused, generating less waste, and consuming less energy. Diesel engines are simple and powerful, and exhibit many advantages in energy efficiency and cost. Therefore, the production of higher fatty acid esters from plant materials has become of interest in recent years for the manufacture of biodiesel, a clean-burning alternative fuel. The industrial production of biodiesel mostly proceeds in the presence of "soluble" catalysts such as alkali hydroxides and liquid acids. A considerable amount of energy is required for the purification of products and catalyst separation, and furthermore these catalysts are not reusable. This process results in substantial energy wastage and the production of large amounts of chemical waste. Particulate heterogeneous catalysts can be readily separated from products following reaction, allowing the catalyst to be reused and consuming less energy. This Minireview describes the environmentally benign production of biodiesel using heterogeneous catalysts such as solid bases, acid catalysts, and immobilized enzymes. [source] Recent Advances in CO2 Capture and UtilizationCHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 11 2008Kerry Yu Dr. Abstract Energy and the environment are two of the most important issues this century. More than 80,% of our energy comes from the combustion of fossil fuels, which will still remain the dominant energy source for years to come. It is agreed that carbon dioxide produced from the combustion process to be the most important anthropogenic greenhouse gas leading to global warming. Atmospheric CO2 concentrations have indeed increased by almost 100,ppm since their pre-industrial level, reaching 384,ppm in 2007 with a total annual emission of over 35,Gt. Prompt global action to resolve the CO2 crisis is therefore needed. To pursue such an action, we are urged to save energy without the unnecessary production of carbon emissions and to use energy in more efficient ways, but alternative methods to mitigate the greenhouse gas have to be considered. This Minireview highlights some recent promising research activities and their prospects in the areas of carbon capture and storage and chemical fixation of CO2 in constructing a future low-carbon global economy with reference to energy source, thermodynamic considerations, net carbon emissions and availability of reagents. [source] Incorporating multiple criteria into the design of conservation area networks: a minireview with recommendationsDIVERSITY AND DISTRIBUTIONS, Issue 2 2006Alexander Moffett ABSTRACT We provide a review of multicriteria decision-making (MCDM) methods that may potentially be used during systematic conservation planning for the design of conservation area networks (CANs). We review 26 methods and present the core ideas of 19 of them. We suggest that the computation of the non-dominated set (NDS) be the first stage of any such analysis. This process requires only that alternatives be qualitatively ordered by each criterion. If the criteria can also be similarly ordered, at the next stage, Regime is the most appropriate method to refine the NDS. If the alternatives can also be given quantitative values by the criteria, Goal Programming will prove useful in many contexts. If both the alternatives and the criteria can be quantitatively evaluated, and the criteria are independent of each other but may be compounded, then multi-attribute value theory (MAVT) should be used (with preferences conveniently elicited by a modified Analytic Hierarchy Process (mAHP) provided that the number of criteria is not large). [source] Application of Nanoparticles in Electrochemical Sensors and BiosensorsELECTROANALYSIS, Issue 4 2006Xiliang Luo Abstract The unique chemical and physical properties of nanoparticles make them extremely suitable for designing new and improved sensing devices, especially electrochemical sensors and biosensors. Many kinds of nanoparticles, such as metal, oxide and semiconductor nanoparticles have been used for constructing electrochemical sensors and biosensors, and these nanoparticles play different roles in different sensing systems. The important functions provided by nanoparticles include the immobilization of biomolecules, the catalysis of electrochemical reactions, the enhancement of electron transfer between electrode surfaces and proteins, labeling of biomolecules and even acting as reactant. This minireview addresses recent advances in nanoparticle-based electrochemical sensors and biosensors, and summarizes the main functions of nanoparticles in these sensor systems. [source] Applications of the rep-PCR DNA fingerprinting technique to study microbial diversity, ecology and evolutionENVIRONMENTAL MICROBIOLOGY, Issue 4 2009Satoshi Ishii Summary A large number of repetitive DNA sequences are found in multiple sites in the genomes of numerous bacteria, archaea and eukarya. While the functions of many of these repetitive sequence elements are unknown, they have proven to be useful as the basis of several powerful tools for use in molecular diagnostics, medical microbiology, epidemiological analyses and environmental microbiology. The repetitive sequence-based PCR or rep-PCR DNA fingerprint technique uses primers targeting several of these repetitive elements and PCR to generate unique DNA profiles or ,fingerprints' of individual microbial strains. Although this technique has been extensively used to examine diversity among variety of prokaryotic microorganisms, rep-PCR DNA fingerprinting can also be applied to microbial ecology and microbial evolution studies since it has the power to distinguish microbes at the strain or isolate level. Recent advancement in rep-PCR methodology has resulted in increased accuracy, reproducibility and throughput. In this minireview, we summarize recent improvements in rep-PCR DNA fingerprinting methodology, and discuss its applications to address fundamentally important questions in microbial ecology and evolution. [source] Human telomeric G-quadruplex: structures of DNA and RNA sequencesFEBS JOURNAL, Issue 5 2010Anh Tuân Phan Telomeres play an important role in cellular aging and cancer. Human telomeric DNA and RNA G-rich sequences are capable of forming a four-stranded structure, known as the G-quadruplex. Such a structure might be important for telomere biology and a good target for drug design. This minireview describes the structural diversity or conservation of DNA and RNA human telomeric G-quadruplexes, discusses structural views on targeting these G-quadruplexes and presents some future challenges for structural studies. [source] Human telomeric G-quadruplex: The current status of telomeric G-quadruplexes as therapeutic targets in human cancerFEBS JOURNAL, Issue 5 2010Stephen Neidle The 3,-ends of human chromosomal DNA terminate in short single-stranded guanine-rich tandem-repeat sequences. In cancer cells, these are associated with the telomere-maintenance enzyme telomerase together with the end-binding protein hPOT1. Small molecules that can compete with these proteins and induce the single-stranded DNA to form quadruplex,ligand complexes are, in effect, able to expose these 3,-ends, which results in the activation of a DNA damage response and selective inhibition of cell growth. Several of these G-quadruplex binding molecules have shown promising anticancer activity in tumour xenograft models, which indicate that the approach may be applicable to the treatment of a wide range of human cancers. This minireview summarizes the available data on these compounds and the challenges posed for drug discovery. [source] | ||||||||||||||||