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Widespread Application (widespread + application)
Selected AbstractsQuantitative X-ray projection microscopy: phase-contrast and multi-spectral imagingJOURNAL OF MICROSCOPY, Issue 2 2002S. C. Mayo Summary We outline a new approach to X-ray projection microscopy in a scanning electron microscope (SEM), which exploits phase contrast to boost the quality and information content of images. These developments have been made possible by the combination of a high-brightness field-emission gun (FEG)-based SEM, direct detection CCD technology and new phase retrieval algorithms. Using this approach we have been able to obtain spatial resolution of < 0.2 µm and have demonstrated novel features such as: (i) phase-contrast enhanced visibility of high spatial frequency image features (e.g. edges and boundaries) over a wide energy range; (ii) energy-resolved imaging to simultaneously produce multiple quasi-monochromatic images using broad-band polychromatic illumination; (iii) easy implementation of microtomography; (iv) rapid and robust phase/amplitude-retrieval algorithms to enable new real-time and quantitative modes of microscopic imaging. These algorithms can also be applied successfully to recover object,plane information from intermediate-field images, unlocking the potentially greater contrast and resolution of the intermediate-field regime. Widespread applications are envisaged for fields such as materials science, biological and biomedical research and microelectronics device inspection. Some illustrative examples are presented. The quantitative methods described here are also very relevant to projection microscopy using other sources of radiation, such as visible light and electrons. [source] A MASTER CLASS IN UNDERSTANDING VARIATIONS IN HEALTHCARECYTOPATHOLOGY, Issue 2006M. Mohammed That there is wide-spread variation in healthcare outcomes cannot be denied. The question is what does the variation mean and what can we do about it? Using a series of well-known case-studies, which include data from the Bristol and Shipman Inquiries, fundamental limitations of traditional methods of understanding variation will be highlighted. These methods, which include comparison with standards, league tables and statistical testing, have flaws and they offer little or no guidance on how to re-act to the variation. Fortunately, there is a theory of variation that overcomes these limitations and provides useful guidance on re-acting to variation, which was developed by Walter Shewhart in the 1920s in an industrial setting. Shewhart's theory of variation found widespread application and won him the accolade ,Father of modern quality control'. His work is central to philosophies of continual improvement. Application of Shewhart's theory of variation, also known as Statistical Process Control (SPC), to case-studies from healthcare will be demonstrated, whilst highlighting the implications and challenges for performance management/monitoring and continual improvement in the healthcare. References:, 1. M A Mohammed, KK Cheng, A Rouse, T Marshall. "Bristol, Shipman and clinical governance: Shewhart's forgotten lessons" The Lancet 2001; 357: 463,7. 2. P Adab, A Rouse, M A Mohammed, T Marshall. "Performance league tables: the NHS deserves better" British Medical Journal 2002; 324: 95,98 [source] The application of transcranial magnetic stimulation in psychiatry and neurosciences researchACTA PSYCHIATRICA SCANDINAVICA, Issue 5 2002P. B. Fitzgerald Objective:,Over recent years transcranial magnetic stimulation (TMS) has become widely applied in the study of neuropsychiatric disorders. The aim of this article is to review the application of TMS as an investigative tool and as a potential therapeutic modality in psychiatric disorders. Method:,A comprehensive literature review. Results:,When applied as an investigative tool, TMS provides innovative ways to directly study the excitability of the cortex, cortical regional connectivity, the plasticity of brain responses and cognitive functioning in illness and disease states. A number of studies suggest the potential of treatment with TMS in disease states, especially in patients with depression, although difficulties exist with the interpretation of the published literature. Conclusion:,TMS has a considerable role in neuropsychiatric research. It appears to have considerable potential as a therapeutic tool in depression, and perhaps a role in several other disorders, although widespread application requires larger trials and establishment of sustained response. [source] Uses and abuses of fractal methodology in ecologyECOLOGY LETTERS, Issue 3 2004J. M. Halley Abstract Fractals have found widespread application in a range of scientific fields, including ecology. This rapid growth has produced substantial new insights, but has also spawned confusion and a host of methodological problems. In this paper, we review the value of fractal methods, in particular for applications to spatial ecology, and outline potential pitfalls. Methods for measuring fractals in nature and generating fractal patterns for use in modelling are surveyed. We stress the limitations and the strengths of fractal models. Strictly speaking, no ecological pattern can be truly fractal, but fractal methods may nonetheless provide the most efficient tool available for describing and predicting ecological patterns at multiple scales. [source] Impedance Spectroscopy: A Powerful Tool for Rapid Biomolecular Screening and Cell Culture MonitoringELECTROANALYSIS, Issue 23 2005Isaac Abstract Dielectric spectroscopy or Electrochemical impedance spectroscopy (EIS) is traditionally used in corrosion monitoring, coatings evaluation, batteries, and electrodeposition and semiconductor characterization. However, in recent years, it is gaining widespread application in biotechnology, tissue engineering, and characterization of biological cells, disease diagnosis and cell culture monitoring. This article discusses the principles and implementation of dielectric spectroscopy in these bioanalytical applications. It provides examples of EIS as label-free, mediator-free strategies for rapid screening of biocompatible surfaces, monitoring pathogenic bacteria, as well as the analysis of heterogeneous systems, especially biological cells and tissues. Descriptions are given of the application of nanoparticles to improve the analytical sensitivities in EIS. Specific examples are given of the detection of base pair mismatches in the DNA sequence of Hepatitis B disease, TaySach's disease and Microcystis spp. Others include the EIS detection of viable pathogenic bacteria and the influence of nanomaterials in enhancing biosensor performance. Expanding applications in tissue engineering such as adsorption of proteins onto thiolated hexa(ethylene glycol)-terminated (EG6) self-assembled monolayer (SAM) are discussed. [source] Nanoparticle Electroluminescence: Controlling Emission Color Through Förster Resonance Energy Transfer in Hybrid ParticlesADVANCED FUNCTIONAL MATERIALS, Issue 22 2009Christopher F. Huebner Abstract Electroluminescent (EL) polymers are attractive for developing all-organic light-emitting devices (OLEDs) due to the potential advantages that polymeric systems may offer in the large-scale manufacturing of electronics. Nonetheless, many of these EL , -conjugated polymers are inherently insoluble in the solvents employed in the intended solution-based manufacturing processes. One such polymer is poly(2,5-dioctyl-1,4-phenylenevinylene) (POPPV), where the inherent lack of solubility of POPPV in organic solvents has frustrated its widespread application in devices and no OLEDs have been presented that exploit its electroluminescence characteristics. In this effort, a unique strategy is presented for the preparation of hybrid nanoparticles composed of POPPV, a green emitter (,em,=,505,nm) and poly(9,9-di- n -octylfluorenyl-2,7-diyl) (PFO), a blue emitter (,em,=,417,nm). The aqueous-based nanoparticle dispersion composed of these hybrid particles is stable to aggregate and can be employed in the construction of OLEDs. The color characteristics of the electroluminescence for the devices can be tuned by exploiting the Förster resonance energy transfer between the polymers within a particle, while suppressing energy transfer between the particles. These aqueous-based nanoparticle dispersions are amenable to being printed into devices through high-throughput manufacturing techniques, for example, roll-to-roll printing. [source] Development of 3-D equivalent-circuit modelling with decoupled L-ILU factorization in semiconductor-device simulationINTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 3 2007Szu-Ju Li Abstract In this paper, we develop a three-dimensional (3-D) device simulator, which combines a simplified, decoupled Gummel-like method equivalent-circuit model (DM) with levelized incomplete LU (L-ILU) factorization. These complementary techniques are successfully combined to yield an efficient and robust method for semiconductor-device simulation. The memory requirements are reduced significantly compared to the conventionally used Newton-like method. Furthermore, the complex voltage-controlled current source (VCCS) is simplified as a nonlinear resistor. Hence, the programming and debugging for the nonlinear resistor model is much easier than that for the VCCS model. Further, we create a connection-table to arrange the scattered non-zero fill-ins in sparse matrix to increase the efficiency of L-ILU factorization. Low memory requirements may pave the way for the widespread application in 3-D semiconductor-device simulation. We use the body-tied silicon-on-insulator MOSFET structure to illustrate the capability and the efficiency of the 3-D DM equivalent-circuit model with L-ILU factorization. Copyright © 2007 John Wiley & Sons, Ltd. [source] The ecological research needs of businessJOURNAL OF APPLIED ECOLOGY, Issue 2 2010Paul R. Armsworth Summary 1.,Businesses have an unrivalled ability to mobilize human, physical and financial capital, often manage large land holdings, and draw on resources and supply products that impact a wide array of ecosystems. Businesses therefore have the potential to make a substantial contribution to arresting declines in biodiversity and ecosystem services. To realize this potential, businesses require support from researchers in applied ecology to inform how they measure and manage their impacts on, and opportunities presented to them by, biodiversity and ecosystem services. 2.,We reviewed papers in leading applied ecology journals to assess the research contribution from existing collaborations involving businesses. We reviewed applications to, and grants funded by, the UK's Natural Environment Research Council for evidence of public investment in such collaborations. To scope opportunities for expanding collaborations with businesses, we conducted workshops with three sectors (mining and quarrying, insurance and manufacturing) in which participants identified exemplar ecological research questions of interest to their sector. 3.,Ten to fifteen per cent of primary research papers in Journal of Applied Ecology and Ecological Applications evidenced business involvement, mostly focusing on traditional rural industries (farming, fisheries and forestry). The review of UK research council funding found that 35% of applications mentioned business engagement, while only 1% of awarded grants met stricter criteria of direct business involvement. 4.,Some questions identified in the workshops aim to reduce costs from businesses' impacts on the environment and others to allow businesses to exploit new opportunities. Some questions are designed to inform long-term planning undertaken by businesses, but others would have more immediate commercial applications. Finally, some research questions are designed to streamline and make more effective those environmental policies that affect businesses. 5.,Business participants were forward-looking regarding ecological questions and research. For example, representatives from mining and quarrying companies emphasized the need to move beyond biodiversity to consider how ecosystems function, while those from the insurance sector stressed the importance of ecology researchers entering into new types of interdisciplinary collaboration. 6.,Synthesis and applications. Businesses from a variety of sectors demonstrated a clear interest in managing their impacts on, and exploiting opportunities created by, ecosystem services and biodiversity. To achieve this, businesses are asking diverse ecological research questions, but publications in leading applied ecology journals and research council funding reveal limited evidence of direct engagement with businesses. This represents a missed opportunity for ecological research findings to see more widespread application. [source] A review of pervaporation for product recovery from biomass fermentation processes,JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2005Leland M Vane Abstract Although several separation technologies are technically capable of removing volatile products from fermentation broths, distillation remains the dominant technology. This is especially true for the recovery of biofuels such as ethanol. In this paper, the status of an emerging membrane-based technology, called pervaporation, for this application is reviewed. Several issues and research priorities which will impact the ability of pervaporation to be competitive for biofuel recovery from fermentation systems are identified and discussed. They include: increased energy efficiency; reduction of capital cost for pervaporation systems; longer term trials with actual fermentation broths; optimized integration of pervaporation with fermentor; synergy of performing both alcohol recovery and solvent dehydration by pervaporation with dephlegmation fractional condensation technology; and updated economic analyses of pervaporation at various biofuel production scales. Pervaporation is currently viable for biofuel recovery in a number of situations, but more widespread application will be possible when progress has been made on these issues. Published in 2005 for SCI by John Wiley & Sons, Ltd. [source] Efficacy of chitosan microspheres for controlled intra-articular delivery of celecoxib in inflamed jointsJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 9 2004Hetal Thakkar The use of polymeric carriers in formulations of therapeutic drug delivery systems has gained widespread application, due to their advantage of being biodegradable and biocompatible. In this study, we aimed to prepare celecoxib-loaded chitosan microspheres for intra-articular administration and to compare the retention of the celecoxib solution and chitosan microspheres in the joint cavity. The microspheres were characterized for entrapment efficiency, particle size and surface morphology by scanning electron microscopy. In-vitro drug release studies of microspheres revealed that the microspheres are able to control the release of celecoxib over a period of 96 h. Biodistribution studies of celecoxib and chitosan microspheres were performed by radiolabelling with 99mTc and injecting intra-articularly in rats. The study indicated that following intra-articular administration the distribution of the drug to the organs, like liver and spleen, is very rapid compared with that of the microspheres. Compared with the drug solution, a 10-fold increase in the concentration of the drug in the joint was observed 24 h post intra-articular injection (P < 0.005) when drug was encapsulated in microspheres. [source] NLPIR: A theoretical framework for applying natural language processing to information retrievalJOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 2 2003Lina Zhou The role of information retrieval (IR) in support of decision making and knowledge management has become increasingly significant. Confronted by various problems in traditional keyword-based IR, many researchers have been investigating the potential of natural language processing (NLP) technologies. Despite widespread application of NLP in IR and high expectations that NLP can address the problems of traditional IR, research and development of an NLP component for an IR system still lacks support and guidance from a cohesive framework. In this paper, we propose a theoretical framework called NLPIR that aims at integrating NLP into IR and at generalizing broad application of NLP in IR. Some existing NLP techniques are described to validate the framework, which not only can be applied to current research, but is also envisioned to support future research and development in IR that involve NLP. [source] Extreme breeding: Leveraging genomics for crop improvementJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 6 2007Siobhan M Brady Abstract The genomic revolution has led to dramatic increases in our understanding of plant biology in the past 10 years, especially in model plant species such as Arabidopsis. The technologies associated with this revolution, such as tilling, array mapping, and association mapping, will see widespread application to crop improvement in the near future. The genes for desirable traits identified through such efforts may be introgressed at an accelerated rate into elite germplasm by marker-assisted breeding. Copyright © 2007 Society of Chemical Industry [source] Nutritional value of African yambean (Sphenostylis stenocarpa L): improvement by lactic acid fermentationJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 6 2005Marshall A Azeke Abstract Tropical African yambean (Sphenostylis stenocarpa L) is an under-utilised hardy, protein-rich legume. Antinutrients and the excessively long cooking time (4,6 h), among other factors, limit the food use of African yambean seeds. To reduce these limitations, non-traditional, less energy-consuming processing methods are required. Seeds of different varieties were (i) examined for ingredients and (ii) fermented with Lactobacillus plantarum. Comparisons with traditionally cooked beans were made. Protein content and in vitro protein digestibility were increased slightly by fermentation or cooking. Reductions in trypsin and ,-amylase inhibitor activity and tannin ranged from significant to complete. The contents of potentially very toxic cyanogenic glycosides and flatulence-causing ,-galactosides were high in raw beans. Reduction by fermentation (by 85%) was clearly more effective than by traditional cooking (10,20%). The results demonstrate (i) that fermentation can substantially improve the nutritional quality and (ii) that the energy requirement to produce a basic consumable fermented food from African yambean is only 10% of that of traditional cooking. On these grounds, widespread application of lactic acid fermentation by individuals or small-scale industries would be advantageous in the context of small-household economy, environmental protection, health and long-term sustainable agriculture in Nigeria. Copyright © 2005 Society of Chemical Industry [source] BOLD contrast sensitivity enhancement and artifact reduction with multiecho EPI: Parallel-acquired inhomogeneity-desensitized fMRIMAGNETIC RESONANCE IN MEDICINE, Issue 6 2006Benedikt A. Poser Abstract Functional MRI (fMRI) generally employs gradient-echo echo-planar imaging (GE-EPI) to measure blood oxygen level-dependent (BOLD) signal changes that result from changes in tissue relaxation time T between activation and rest. Since T strongly varies across the brain and BOLD contrast is maximal only where the echo time (TE) equals the local T, imaging at a single TE is a compromise in terms of overall sensitivity. Furthermore, the long echo train makes EPI very sensitive to main field inhomogeneities, causing strong image distortion. A method is presented that uses accelerated parallel imaging to reduce image artifacts and acquire images at multiple TEs following a single excitation, with no need to increase TR. Sensitivity gains from the broadened T coverage are optimized by pixelwise weighted echo summation based on local T or contrast-to-noise ratio (CNR) measurements. The method was evaluated using an approach that allows differential BOLD CNR to be calculated without stimulation, as well as with a Stroop experiment. Results obtained at 3 T showed that BOLD sensitivity improved by 11% or more in all brain regions, with larger gains in areas typically affected by strong susceptibility artifacts. The use of parallel imaging markedly reduces image distortion, and hence the method should find widespread application in functional brain imaging. Magn Reson Med, 2006. © 2006 Wiley-Liss, Inc. [source] Short-Term Antiandrogen Flutamide Treatment Causes Structural Alterations in Somatic Cells Associated with Premature Detachment of Spermatids in the Testis of Pubertal and Adult Guinea PigsREPRODUCTION IN DOMESTIC ANIMALS, Issue 3 2010LR Maschio Contents In spite of widespread application of flutamide in the endocrine therapies of young and adult patients, the side effects of this antiandrogen on spermatogenesis and germ-cell morphology remain unclear. This study evaluates the short-term androgen blockage effect induced by the administration of flutamide to the testes of pubertal (30-day old) and adult (65- and 135-day old) guinea pigs, with an emphasis on ultrastructural alterations of main cell types. The testes removed after 10 days of treatment with either a non-steroidal antiandrogen, flutamide (10 mg/kg of body weight) or a pharmacological vehicle alone were processed for histological, quantitative and ultrastructural analysis. In pubertal animals, flutamide androgenic blockage induces spermatogonial differentiation and accelerates testes maturation, causing degeneration and detachment of primary spermatocytes and round spermatids, which are subsequently found in great quantities in the epididymis caput. In post-pubertal and adult guinea pigs, in addition to causing germ-cell degeneration, especially in primary spermatocytes, and leading to the premature detachment of spherical spermatids, the antiandrogen treatment increased the relative volume of Leydig cells. In addition, ultrastructural evaluation indicated that irrespective of age antiandrogen treatment causes an increase in frequency of organelles involved with steroid hormone synthesis in the Leydig cells and a dramatic accumulation of myelin figures in their cytoplasm and, to a larger degree, in Sertoli cells. In conclusion, the transient exposition of the guinea pigs to flutamide, at all postnatal ages causes some degenerative lesions including severe premature detachment of spermatids and accumulation of myelin bodies in Leydig and Sertoli cells, compromising, at least temporarily, the spermatogenesis. [source] Predictors of Candidate Maturation Among Potential Living DonorsAMERICAN JOURNAL OF TRANSPLANTATION, Issue 10 2005Elizabeth C. Verna The shortage of deceased donor allografts and improved outcomes in partial organ transplantation have led to widespread application of adult-to-adult living donor liver transplantation. Donor selection limits overall utilization of this technique and predictors of candidate maturation have been inadequately studied to date. We therefore collected data on 237 consecutive potential donors including their age, sex, ethnicity, relationship to the recipient, education, employment and religious beliefs and practices. Of these 237 candidates, 91 (38%) were excluded for medical and psychosocial reasons, 53 (22%) withdrew from the process predonation and 93 (39%) underwent partial liver donation. In multivariate analyses, the relationship between the donor and the recipient was highly predictive of successful donation. For pediatric recipients, no parents voluntarily withdrew from the evaluation process. For adult recipients, spouses are the most likely to donate, followed by parents, children and siblings. Additional predictors for donation included self-description as religious but not regularly practicing, part-time employment and higher education. Race, ethnicity, gender and age did not predict donation in multivariate analysis. Further understanding of the complex decision to donate may improve donation rates as well as permit more efficient and cost-effective donor evaluation strategies. [source] Split-Liver Transplantation: A ReviewAMERICAN JOURNAL OF TRANSPLANTATION, Issue 11 2003John F. Renz Split-liver transplantation (SLT), a procedure where one cadaver liver is divided to provide for two recipients, offers immediate expansion of the existing cadaver donor pool. To date, the principal beneficiaries of SLT have been adult/pediatric recipient pairs with excellent outcomes reported; however, the current scarcity of cadaver organs has renewed interest in expanding these techniques to include two adult recipients from one adult cadaver donor. Significant obstacles to the widespread application of SLT exist and must be resolved by the transplant community before greater utilization can be realized. This manuscript reviews the historic background, surgical techniques, current results, and obstacles impeding further application of SLT. [source] Identifying the origins of fishing gear ingested by seabirds: a novel multivariate approachAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 6 2010Cindy Ridley Abstract 1.The global decline of albatrosses (Diomedidae: Procellariiformes) is thought to have occurred largely as a direct result of fishery-related mortality. Albatrosses and other large petrels interact with fisheries in several ways, including scavenging used bait and discarded offal, which may contain hooks. 2.Hooks that are ingested by breeding birds are often fed to chicks which subsequently regurgitate them shortly before fledging. 3.In this study a series of mathematical (cladistic, cluster and principal components) analyses are applied to a sample of 241 items of fishing gear (hook, snood and hook/snood unit) collected from seabird nest sites on Bird Island, South Georgia, and 44 reference gear items provided by four South Atlantic regional fisheries. 4.The five separate analyses failed to assign most gear to a particular fishery or to identify any consistent annual trends. The homogeneous nature of the material, which was largely derived from the same manufacturers, meant that gear origin could not be determined. This suggests that hooks found at seabird colonies in this, and potentially other regions, will be of limited use in identifying offending fisheries, unless operators are obliged to deploy gear with unique marks in the future. 5.Nevertheless, it is suggested that this approach should work effectively where birds interact with a range of fisheries targeting different species using variable gear. This study therefore represents an innovative approach to the characterization of lost fishing gear with potentially widespread application. Copyright © 2010 John Wiley & Sons, Ltd. [source] P/Pd Types Of Override Control SystemsASIAN JOURNAL OF CONTROL, Issue 4 2002Yaw-Ying Tsai ABSTRACT The override control provides protective action against abnormal operation and/or incipient process failure. In terms of control theory, it is a logic-based switching system and, in terms of operation, it is usually activated between the soft constraint and the hard constraint. It is used in all process industries, and most PID control loops are patched with some type of override system. Despite widespread application, little research has been done to analyze override control systems. In this work, the properties of the override control are explored. The stability of the override control is also studied. Counter to intuition, many well-known override systems may exhibit instability and lead to oscillatory responses as the process approaches constraints. Approaches are proposed for the design of override control systems to ensure inherent safe operation. [source] Sources and bioavailability of phosphorus fractions in freshwaters: a British perspectiveBIOLOGICAL REVIEWS, Issue 1 2001C. S. REYNOLDS ABSTRACT This paper seeks a perspective on the forms of phosphorus which promote aquatic eutrophication, with the particular quest of establishing their sources. A short background traces the development of understanding of nutrient enrichment and the suppositions about the relative contributions of agriculture, sewage and detergent residues. Most aquatic systems, and their primary producers, are naturally deficient in biologically-available phosphorus. Aquatic plants have evolved very efficient phosphorus uptake mechanisms. The biomass responses to an increase in the supply of phosphorus are stoichiometrically predictable. The most bioavailable forms of phosphorus are in solution, as orthophosphate ions, or are readily soluble or elutable from loose combinations. Ready bioavailability coincides well with what is measurable as molybdate-reactive (MRP) or soluble-reactive phosphorus (SRP). Most other forms, including phosphates of the alkaline earth metals, aluminium and iron are scarcely available at all. Orthophosphate ions sorbed to metal oxides and hydroxides are normally not biologically available either, except through weak dissociation (,desorption'). The production of alkaline phosphatase provides organisms with an additional mechanism for accelerating the sequestration of phosphate from organic compounds. Bioavailable phosphate is liberated when redox- or alkali-sensitive metal hydroxides dissolve but these processes are minor contributors to the biological responses to nutrient enrichment. Most of the familiar eutrophication is attributable to the widespread application of secondary sewage treatment methods to the wastes emanating from a burgeoning and increasingly urbanised human population. The use of polyphosphate-based detergents, now in decline, has contributed to the problem. In aquatic systems, the additional phosphorus raises the biological supportive capacity, sometimes to the capacity of the next limiting factor (carbon, light, hydraulic retention or of another nutrient). At high orthophosphate loadings, the straight stoichiometric yield relationship between biomass yield and phosphorus availability is lost. Movements of phosphorus and its recycling within aquatic systems do not prevent the slow gravitation of phosphorus to the bottom substrata. The phosphorus retentivity of sediments depends upon their chemical composition. While oxide-hydroxide binding capacity in the surface sediments persists, they act as a sink for phosphorus and a control on further cycling. Iron-rich and clay-rich sediments perform best in these conditions; calcareous sediments least so. Eutrophication may lead to the exhaustion of sediment P-binding capacity. Non-sorbed phosphate is readily recyclable if primary producers have access to it. Recycling is most rapid in shallow waters (where sediment disturbance, by flow, by wind action and through bioturbation, is frequent) and least in deep ventilated sediments. The contributions of phosphorus from catchments are assessed. The slow rate of weathering of (mostly apatitic) minerals, the role of chemical binding in soils and the incorporation and retentivity by forested terrestrial ecosystems each contribute to the minimisation of phosphorus leakage to drainage waters. Palaeolimnological and experimental evidence confirms that clearance of land and ploughing its surface weakens the phosphorus retentivity of catchments. The phosphorus transferred from arable land to drainage remains dominated by sorbed fractions which are scarcely bioavailable. Some forms of intensive market gardening or concentrated stock rearing may mobilise phosphates to drainage but it is deduced that drainage from agricultural land is not commonly a major source of readily bioavailable phosphorus in water. Careful budgeting of the phosphates in run-off from over-fertilised soils may nevertheless show that a proportionately small loss of bioavailable phosphorus can still be highly significant in promoting aquatic plant production. The bioavailable-phosphorus (BAP) load achieving the OECD threshold of lake eutrophy (35 mg P m,3) is calculated to be equivalent to a terrestrial loss rate of approximately 17.5 kg BAP km,2 year,1), or only 1,2% of a typical fertiliser application. The output is shown to be comparable with the P yield from secondary treatment of the sewage produced by a resident population of 30,44 persons km,2. With tertiary treatment, the equivalence is with approximately 200 persons km,2. [source] Microreactor Technology: A Revolution for the Fine Chemical and Pharmaceutical Industries?CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 3 2005D. M. Roberge Abstract 50,% of reactions in the fine chemical/pharmaceutical industry could benefit from a continuous process based mainly on microreactor technology. However, the frequent presence of a solid phase still hinders the widespread application of such a technology as a multi-purpose solution. For small scale and pilot productions, speed in process R&D, as well as the avoidance of scale-up issues, are the main drivers. On the other hand, for large scale productions, a gain in yield and safety are the main motivations for the use of micoreactor technology. The gain in yield must be significant in order to cope with the increase in capital expenditure associated with the development of a new technology. [source] A Time-Resolved Spectroscopic Study of the Bichromophoric Phototrigger 3,,5,-Dimethoxybenzoin Diethyl Phosphate: Interaction Between the Two Chromophores Determines the Reaction PathwayCHEMISTRY - A EUROPEAN JOURNAL, Issue 17 2010Chensheng Ma Dr. Abstract 3,,5,-Dimethoxybenzoin (DMB) is a bichromophoric system that has widespread application as a highly efficient photoremovable protecting group (PRPG) for the release of diverse functional groups. The photodeprotection of DMB phototriggers is remarkably clean, and is accompanied by the formation of a biologically benign cyclization product, 3,,5,-dimethoxybenzofuran (DMBF). The underlying mechanism of the DMB deprotection and cyclization has, however, until now remained unclear. Femtosecond transient absorption (fs-TA) spectroscopy and nanosecond time-resolved resonance Raman (ns-TR3) spectroscopy were employed to detect the transient species directly, and examine the dynamic transformations involved in the primary photoreactions for DMB diethyl phosphate (DMBDP) in acetonitrile (CH3CN). To assess the electronic character and the role played by the individual sub-chromophore, that is, the benzoyl, and the di- meta -methoxybenzylic moieties, for the DMBDP deprotection, comparative fs-TA measurements were also carried out for the reference compounds diethyl phosphate acetophenone (DPAP), and 3,,5,-dimethoxybenzylic diethyl phosphate (DMBnDP) in the same solvent. Comparison of the fs-TA spectra reveals that the photoexcited DMBDP exhibits distinctly different spectral character and dynamic evolution from those of the reference compounds. This fact, combined with the related steady-state spectral and density functional theoretical results, strongly suggests the presence in DMBDP of a significant interaction between the two sub-chromophores, and that this interaction plays a governing role in determining the nature of the photoexcitation and the reaction channel of the subsequent photophysical and photochemical transformations. The ns-TR3 results and their correlation with the fs-TA spectra and dynamics provide evidence for a novel concerted deprotection,cyclization mechanism for DMBDP in CH3CN. By monitoring the direct generation of the transient DMBF product, the cyclization time constant was determined unequivocally to be ,1,ns. This indicates that there is little relevance for the long-lived intermediates (>10,ns) in giving the DMBF product, and excludes the stepwise mechanism proposed in the literature as the major pathway for the DMB cyclization reaction. This work provides important new insights into the origin of the 3,,5,-dimethoxy substitution effect for the DMB photodeprotection. It also helps to clarify the many different views presented in previous mechanistic studies of the DMB PRPGs. In addition to this, our fs-TA results on the reference compound DMBnDP in CH3CN provide the first direct observation (to the best of our knowledge) showing the predominance of a prompt (,2,ps) heterolytic bond cleavage after photoexcitation of meta -methoxybenzylic compounds. This provides insight into the long-term controversies about the photoinitiated dissociation mode of related substituted benzylic compounds. [source] Laparoscopic colonic surgery , mission accomplished or work in progress?COLORECTAL DISEASE, Issue 6 2006H. Kehlet Abstract Laparoscopic colonic resection may facilitate early postoperative recovery due to reduced surgical stress, pain and ileus. However, large randomised studies have only shown marginal improvements in outcome compared with open surgery, reporting a median hospital stay of about 5,7 days. Concomitant with these developments multimodal rehabilitation, which involves a revision of general postoperative care principles, improved pain relief with epidural analgesia and early oral nutrition and mobilization, has demonstrated greater improvements in recovery after open surgery, resulting in a median hospital stay of about 2,4 days. Recent single centre, randomised studies where laparoscopic and open colonic resection are combined with multimodal rehabilitation have not resolved the debate regarding which is the optimal operative technique. Therefore, new strategies are required to integrate laparoscopy with multimodal rehabilitation in order to establish its advantages, cost effectiveness and indications in specific groups of patients or colorectal procedures, thus justifying widespread application of the laparoscopic technique. [source] Efficacy of magnifying chromoendoscopy for the differential diagnosis of colorectal lesions,DIGESTIVE ENDOSCOPY, Issue 2 2005Yasushi Sano Magnifying chromoendoscopy is an exciting new tool and offers detailed analysis of the morphological architecture of mucosal crypt orifices. In this review, we principally show the efficacy of magnifying chromoendoscopy for the differential diagnosis of colorectal lesions such as prediction between non-neoplastic lesions and neoplastic ones, and distinction between endoscopically treatable early invasive cancers and untreatable cancers based on a review of the literature and our experience at two National Cancer Centers in Japan. Overall diagnostic accuracy by conventional view, chromoendoscopy and chromoendoscopy with magnification ranged from 68% to 83%, 82% to 92%, and 80% to 96%, respectively, and diagnostic accuracy of accessing the stage of early colorectal cancer using magnifying colonoscopy was over 85%. Although the reliability depends on the skill in magnifying observation, widespread applications of the magnification technique could influence the indications for biopsy sampling during colonoscopy and the indication for mucosectomy. Moreover, the new detailed images seen with magnifying chromoendoscopy are the beginning of a new period in which new optical developments, such as narrow band imaging system, endocytoscopy system, and laser-scanning confocal microscopy, will allow a unique look at glandular and cellular structures. [source] Status and development of PEM fuel cell technologyINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 5 2008F. Barbir Abstract Fuel cells are an emerging technology with applications in transportation, stationary and portable power generation, with outputs ranging from mW to MW. The most promising and most widely researched, developed and demonstrated type of fuel cells is proton exchange membrane (PEM) fuel cell. State of the art in PEM fuel cell technology and challenges in their development and widespread applications are discussed. Copyright © 2007 John Wiley & Sons, Ltd. [source] Electronic structure and physicochemical properties of selected penicillinsINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 3 2007Catalina Soriano-Correa Abstract Traditionally, penicillins have been used as antibacterial agents due to their characteristics and widespread applications with few collateral effects, which have motivated several theoretical and experimental studies. Despite the latter, their mechanism of biological action has not been completely elucidated. We present a theoretical study at the Hartree,Fock and density functional theory (DFT) levels of theory of a selected group of penicillins such as the penicillin-G, amoxicillin, ampicillin, dicloxacillin, and carbenicillin molecules, to systematically determine the electron structure of full ,-lactam antibiotics. Our results allow us to analyze the electronic properties of the pharmacophore group, the aminoacyl side-chain, and the influence of the substituents (R and X) attached to the aminoacyl side-chain at 6, (in contrast with previous studies focused at the 3, substituents), and to corroborate the results of previous studies performed at the semiempirical level, solely on the ,-lactam ring of penicillins. Besides, several density descriptors are determined with the purpose of analyzing their link to the antibacterial activity of these penicillin compounds. Our results for the atomic charges (fitted to the electrostatic potential), the bond orders, and several global reactivity descriptors, such as the dipole moments, ionization potential, hardness, and the electrophilicity index, led us to characterize: the active sites, the effect of the electron-attracting substituent properties and their physicochemical features, which altogether, might be important to understand the biological activity of these type of molecules. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 [source] Sensing of toxic metals through pH changes using a hybrid sorbent material: Concept and experimental validationAICHE JOURNAL, Issue 11 2009Prasun K. Chatterjee Abstract This article reports a new hybrid sorbent material that is capable of detecting trace concentration of toxic metals, such as zinc, lead, copper, nickel, etc., through pH changes only. The material is essentially a composite granular material synthesized through rapid fusion of a mixture of amorphous hydrated ferric oxide (HFO) and akermanite or calcium magnesium silicate (Ca2MgSi2O7). When a water sample is rapidly passed through a mini-column containing this hybrid material, effluent pH at the exit always remains alkaline (,9.0) because of slow hydrolysis of akermanite and steady release of hydroxyl (OH,) ions. This exit solution turns pink through the addition of a phenolphthalein indicator. Commonly encountered electrolytes containing sodium, calcium, chloride, and sulfate have no impact on the exit pH from the mini-column. However, when trace concentration of a heavy metal (say lead) is present in the sample water, a considerable drop in pH (>2 units) is observed for the exiting solution. At this point, the solution turns colorless through the addition of a phenolphthalein indicator. Moreover, the change in the slope of pH, i.e., ,dpH/dBV, provides a sharp, noticeable peak for each toxic metal where BV is the bed volumes of solution fed. The technique allowed detection of zinc and lead through pH swings in synthesized samples, spiked Bethlehem City water, and also in Lehigh River water in the presence of phosphate and natural organic matter (NOM). Using a simple preconcentration technique, lower than 10 ,g/l of lead was detected with a significant peak. From a mechanistic viewpoint, high sorption affinity of HFO surface sites toward toxic metal cations, ability of akermanite to maintain near-constant alkaline pH for a prolonged period through slow hydrolysis and labile metal-hydroxy complex formation causing dissipation of OH, ions from the aqueous phase provide a synergy that allows detection of toxic metals at concentrations well below 100 ,g/l through pH changes. Nearly all previous investigations pertaining to toxic metals sensing use metal-selective enzymes or organic chromophores. This simple-to-operate technique using an inexpensive hybrid material may find widespread applications in the developing world for rapid detection of toxic metals through pH changes. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Highly efficient square wave distant dipolar field and its application for in vivo MRIMAGNETIC RESONANCE IN MEDICINE, Issue 4 2010Congbo Cai Abstract Intermolecular multiple quantum coherences generated by distant dipolar field (DDF) have some attractive properties, but the intrinsic weak signal intensity prevents their widespread applications. Recently, Branca et al. (J Chem Phys 2008;129:054502) suggested that square wave DDF was more efficient than conventional sinusoidal DDF because it could simultaneously produce intermolecular multiple quantum coherences signal with various major orders. In this article, instead of a series of adiabatic inversion pulses proposed previously, a more efficient composite adiabatic inversion pulse was applied to create square wave DDF. The square wave DDF was applied to in vivo MRI for the first time, and the corresponding simulations were performed. Both experimental and simulated results show that square wave DDF with composite adiabatic inversion pulse improves over the original Z-modulation enhanced to binary for self-refocused acquisition implementation and can enhance the signal intensity to about 2-fold of that from conventional correlation spectroscopy (COSY) revamped with asymmetric Z-gradient echo detection sequence for in vivo MRI, close to the theoretical prediction. Magn Reson Med, 2010. © 2010 Wiley-Liss, Inc. [source] On the solution of an initial-boundary value problem that combines Neumann and integral condition for the wave equation,NUMERICAL METHODS FOR PARTIAL DIFFERENTIAL EQUATIONS, Issue 1 2005Mehdi Dehghan Abstract Numerical solution of hyperbolic partial differential equation with an integral condition continues to be a major research area with widespread applications in modern physics and technology. Many physical phenomena are modeled by nonclassical hyperbolic boundary value problems with nonlocal boundary conditions. In place of the classical specification of boundary data, we impose a nonlocal boundary condition. Partial differential equations with nonlocal boundary specifications have received much attention in last 20 years. However, most of the articles were directed to the second-order parabolic equation, particularly to heat conduction equation. We will deal here with new type of nonlocal boundary value problem that is the solution of hyperbolic partial differential equations with nonlocal boundary specifications. These nonlocal conditions arise mainly when the data on the boundary can not be measured directly. Several finite difference methods have been proposed for the numerical solution of this one-dimensional nonclassic boundary value problem. These computational techniques are compared using the largest error terms in the resulting modified equivalent partial differential equation. Numerical results supporting theoretical expectations are given. Restrictions on using higher order computational techniques for the studied problem are discussed. Suitable references on various physical applications and the theoretical aspects of solutions are introduced at the end of this article. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2005 [source] Global Model of He/O2 and Ar/O2 Atmospheric Pressure Glow DischargesPLASMA PROCESSES AND POLYMERS, Issue 6 2008Ganyoung Park Abstract Atmospheric pressure glow discharges (APGDs) have widespread applications, including sterilization, cancer cell treatment, deposition, and surface modification due to their rather simple configurations, thanks to no need for vacuum system and their great capability to generate reactive species such as radical oxygen species. Helium and argon are widely used as feeding gases, achieving stable operations for wide ranges of parameters in atmospheric pressure, and oxygen is added into these gases to generate more reactive oxygen species (ROS), which play a significant role in sterilization. As the measurements of species densities and electron temperature in APGDs are difficult, we have developed the zero-dimensional global model of He/O2 and Ar/O2 APGDs to calculate the densities of several kinds of species and electron temperature. It was shown that even though small fraction of oxygen less than 1% was added to helium or argon, electrons dissipated most of their energy through collisions with oxygen molecules rather than helium or argon atoms. The densities of electron, atomic oxygen, and ozone of Ar/O2 were higher than those of He/O2; however, the electron temperature of He/O2 was higher than that of Ar/O2. When the pulsed power is applied, the time-averaged electron temperature for the shorter pulse period and the larger duty ratio increased, and the electron density decreased as the duty ratio increased. [source] | |||||||||||||||||||||||||