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Potential Route (potential + route)
Selected AbstractsTin(II) Doped Anatase (TiO2) Nanoparticles: A Potential Route to "Greener" Yellow PigmentsCHEMISTRY - AN ASIAN JOURNAL, Issue 6 2009Moumita Ghosh Dr. Abstract Benign by design: Tin(II) doped anatase TiO2 nanoparticles, a potential candidate as environmentally benign yellow pigments, have been synthesized. The presence of Sn2+ in anatase structure has been confirmed by various analytical techniques including optical and 119Sn Mössbauer spectroscopy. During our exploration of compounds in the SnII -TiIV -O system, we discovered that hydrolysis of titanium alkoxide solution in the presence of SnII salts resulted in stable deep-yellow colored anatase nanoparticles. The samples were characterized by X-ray powder diffraction, electron microprobe, thermal analysis, transmission electron microscopy, and 119Sn Mössbauer spectroscopy. Mössbauer data of the yellow colored samples showed the presence of both SnII and SnIV in a distorted environment as expected in the anatase structure. It is suggested that the cationic charge imbalance is compensated by oxygen vacancies and/or hydroxyl groups as evidenced by Mössbauer data which show two types of SnII environments. When heated in air to 300,°C the samples changed color to completely white and 119Sn Mössbauer data of these samples showed only the presence of SnIV. These observations indicate that the origin of the yellow color in our Sn doped anatase nanoparticles arises from filled Sn 5s states just above the O 2p band, thus decreasing the band gap. The SnII doped anatase TiO2 nanoparticles reported here can potentially lead to environmentally benign yellow pigments. The simplistic nature of the synthetic procedure could easily be adapted to large-scale industrial manufacture. [source] Optimization of process parameters by Taguchi method in the recovery of lactose from whey using sonocrystallizationCRYSTAL RESEARCH AND TECHNOLOGY, Issue 7 2010S. R. Patel Abstract Anti-solvent crystallization of lactose in the presence of ultrasound will reduce crystal size and the level of agglomeration as compared to the commercial cooling crystallization. It offers a potential route to enhance the physical properties as well as the rapid recovery of lactose. Since lactose recovery itself can reduce biological oxygen demand of whey by more then 80%, recovery of lactose from dairy waste stream (whey) solves the problems of dairy industries by improving economics of whey utilization and pollution reduction. In the present study, recovery of lactose from partially deproteinated whey using an anti-solvent (acetone) by sonocrystallization was optimized for finding the most influencing operating parameters; such as sonication time, anti-solvent concentration, initial lactose concentration in the whey and initial pH of sample mixture at three levels using L9 -orthogonal method. The responses were analyzed for recovery of lactose from whey. The anti-solvent concentration and the sonication time were found to be most influencing parameters for the recovery of lactose and the recovery of lactose was found to be 89.03% at the identified optimized level. The crystal size distribution of recovered lactose was found to be narrower (2.5 , 6.5 ,m) as compared to the commercial lactose crystals (3.5 , 9.5 ,m). (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Remobilization of Polychlorinated Biphenyl from Baltic Sea Sediment: Comparing the Roles of Bioturbation and Physical ResuspensionENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2009Jenny E. Hedman Abstract The release of a 14C-labeled trichlorobiphenyl compound ([14C]PCB 32) from sediment to water was quantified weekly in a 30-d microcosm experiment with recirculating water. Two modes of bioturbation-driven polychlorinated biphenyl (PCB) release,bioturbation by the amphipod Monoporeia affinis (a particle biodiffuser) and bioturbation by the polychaete Marenzelleria sp. (a bioirrigator),were compared to the PCB release caused by physical resuspension of the sediment generated by a motor-driven paddle used twice a week. Bioturbation by the amphipod M. affinis caused a significantly higher remobilization of both particle-associated PCB (PCBpart) and dissolved PCB (PCBdiss) than the other treatments. Bioturbation by Marenzelleria sp. and physical resuspension caused a similar release of PCBdiss despite a significantly higher amount of total suspended solids in the water column after physical resuspension. In all treatments, the release of PCBdiss was more than one order of magnitude higher than that of PCBpart, indicating a significant potential route of exposure for pelagic organisms, such as fish, to the most bioavailable PCB form. Calculated mass-transfer coefficients (0.3,1.3 cm/d) correspond to previously reported values for trichlorinated PCBs. The present results indicate that biological reworking of sediments can be just as, or even more, important than physical resuspension for the remobilization of sediment-bound contaminants. [source] Recruiting new neurons from the subventricular zone to the rat postnatal cortex: an organotypic slice culture modelEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2008A. G. Dayer Abstract The neurogenic subventricular zone (SVZ) of the lateral ventricle is a potential source for neuronal replacement in the postnatal or adult neocortex after injury. Here we present a novel model system to directly explore the cellular mechanisms of this process. In order to visualize directed migration from the SVZ towards the cortex, we transplanted green fluorescent protein-labeled progenitor/stem cells into the SVZ of newborn rats. At 2 days after transplantation, we generated organotypic slice cultures and applied fluorescent time-lapse imaging to explore directly the migration and integration of donor cells into the host tissue for up to 2 weeks. Our studies revealed that subventricular grafts provide a significant number of immature neurons to neocortical regions. In the cortex, immature neurons first migrate radially towards the pial surface and then differentiate into GABAergic interneurons. We conclude that our model system presents a novel and effective experimental paradigm to evaluate the recruitment of SVZ-derived neurons into the postnatal cortex, a phenomenon that may represent a potential route for cortical repair. [source] Biomimetic Silica Formation: Effect of Block Copolypeptide Chemistry and Solution Conditions on Silica Nanostructure,ADVANCED MATERIALS, Issue 19 2007J.-S. Jan Biomimetic syntheses of silicas using block copolypeptides containing a hydrophilic lysine block are reported. Porous silica platelets or spheres can be made using block copolypeptides as templates. The results show that biomimetic synthesis under benign conditions may be a potential route for assembling nanostructured materials. [source] Role of atypical protein kinase C isozymes and NF-,B in IL-1,-induced expression of cyclooxygenase-2 in human myometrial smooth muscle cellsJOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2007Sara V. Duggan Increased myometrial expression of cyclooxygenase-2 (Cox-2) at term results from elevated local levels of inflammatory cytokines, and its inhibition provides a potential route for intervention in human pre-term labor. We have identified a role for atypical protein kinase C (PKC) isozymes in IL-1,-induced Cox-2 expression in human myometrial smooth muscle cells (HMSMC). The PKC inhibitor GF109203X (10 µM) inhibited IL-1,-induced Cox-2 protein and RNA expression, which were also reduced by MAPK and nuclear factor ,B (NF-,B) inhibitors. GF109203X did not affect MAPK activities, and neither did it replicate the effect of p38 MAPK inhibition on Cox-2 mRNA stability, suggesting that PKC operates through an independent mechanism. The effect of GF109203X remained intact after depletion of conventional and novel PKC isozymes by phorbol ester pre-treatment. In contrast LY379196 (10 µM), which at micromolar concentrations inhibits all but atypical PKCs, did not affect Cox-2 expression. A peptide corresponding to the pseudosubstrate sequence of atypical PKCs blocked Cox-2 protein expression, whereas the sequence from conventional PKCs was ineffective. GF109203X did not affect NF-,B binding to nuclear proteins, but strongly reduced NF-,B-dependent transcription in luciferase reporter assays. Our findings indicate that IL-1,-induced Cox-2 expression in HMSMC in culture requires p38-MAPK-mediated mRNA stabilization and an independent activation of Cox-2 transcription which is dependent on the action of atypical PKCs, probably through direct stimulation of the transactivating activity of NF-,B. J. Cell. Physiol. 210: 637,643, 2007. © 2006 Wiley-Liss, Inc. [source] Multiple functions of the paranodal junction of myelinated nerve fibers,JOURNAL OF NEUROSCIENCE RESEARCH, Issue 15 2009Jack Rosenbluth Abstract Myelin sheaths include an extraordinary structure, the "paranodal axoglial junction" (PNJ), which attaches the sheath to the axon at each end of each myelin segment. Its size is enormous and its structure unique. Here we review past and current studies showing that this junction can serve multiple functions in maintaining reliable saltatory conduction. The present evidence points to three functions in particular. 1) It seals the myelin sheath to the axon to prevent major shunting of nodal action currents beneath the myelin sheath while still leaving a narrow channel interconnecting the internodal periaxonal space with the perinodal space. This pathway represents a potential route through which juxtaparanodal and internodal channels can influence nodal activity and through which nutrients, such as glucose, and other metabolites can diffuse to and from the internodal periaxonal space. 2) It serves as a mechanism for maintaining discrete, differentiated axolemmal domains at and around the node of Ranvier by acting as a barrier to the lateral movement of ion channel complexes within the axolemma, thus concentrating voltage-gated sodium channels at the node and segregating fast voltage-gated potassium channels to the juxtaparanode under the myelin sheath. 3) It attaches the myelin sheath to the axon on either side of the node and can thus maintain nodal dimensions in the face of mechanical stresses associated with stretch or other local factors that might cause disjunction. It is therefore the likely means for maintaining constancy of nodal surface area and electrical parameters essential for consistency in conduction. © 2009 Wiley-Liss, Inc. [source] Science education in urban settings: Seeking new ways of praxis through critical ethnographyJOURNAL OF RESEARCH IN SCIENCE TEACHING, Issue 8 2001Angela Calabrese Barton The challenges faced in urban science education are deeply rooted in the ongoing struggle for racial, class and gender equity. Part of this struggle is tied to huge differences in class and involves making more equitable the distribution of resources. Another part of this struggle is tied to the rich diversity of children who attend urban schools and involves generating new ways of understanding, valuing, and genuinely incorporating into school-based practices the culture, language, beliefs, and experiences that these children bring to school. Thus, this article argues that to address these two challenges,and indeed to achieve a more just science education for all urban students, explicitly political research methodologies must be considered and incorporated into urban education. One potential route for this is critical ethnography, for this kind of methodology emerges collaboratively from the lives of the researcher and the researched and is centrally about praxis and a political commitment to the struggle for liberation and in defense of human rights. In making this argument, I have drawn from stories from my own research with homeless children. © 2001 John Wiley & Sons, Inc. J Res Sci Teach 38: 899,917, 2001 [source] Synthesis and Mechanism of Ferroelectric Potassium Tantalate Niobate Nanoparticles by the Solvothermal and Hydrothermal ProcessesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 5 2007Nian Wei High-purity KTa0.3Nb0.7O3 nanoparticles have been successfully synthesized by hydrothermal and solvothermal methods. The KOH concentration and the solvent composition have significant effects on the final products. The synthesis mechanism was discussed. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy investigations show that the typical samples solvothermally synthesized are nanosized, well crystallized, and single crystalline. The KTa0.3Nb0.7O3 shows a pseudo-cubic to tetragonal transition with increasing crystallite size. It is believed that supercritical isopropanol plays an important role in synthesizing KTa0.3Nb0.7O3 nanoparticles under milder conditions than the hydrothermal route. The present solvothermal method provides a new potential route for synthesizing ferroelectric potassium tantalate niobate material. [source] Ways of seeing environmental change: Participatory research engagement in Yunnan, China, with ethnic minority Hani participantsASIA PACIFIC VIEWPOINT, Issue 2 2010John McKinnon Abstract In this article, I reflect on a participatory learning and action (PLA) and participatory geographic information system (PGIS) project undertaken in two adjacent Hani villages in southern Yunnan, China. After a lengthy process to gain research authorisations, Hani villagers worked with a group of visiting researchers (Hani, Han Chinese and New Zealanders) to articulate local visions of land-use change and environmental challenges. PLA exercises produced a diverse range of hand-made and PGIS products over a 10-week period. As villagers became more accustomed to the ,outsider team', methods , both designed and spontaneous , diversified. Afterwards, based on the results and acting on their own initiative, local leaders backed by popular support moved quickly to reassert traditional and ritually prescribed Hani conservation measures. Nevertheless, these endogenously driven solutions were not necessarily universally beneficial. In describing the complexities encountered in implementing a participatory framework and the ambiguities of the outcomes engendered, I argue that privileging local coherence and celebrating such participatory approaches should not be done at the expense of ignoring the intricacies of on-going contradictory behaviours in a rapidly changing arena. Yet, in China, where authorities often remain suspicious of those seeking to undertake long-term fieldwork, especially among ethnic minorities, PLA offers a potential route forward. [source] Sacral distribution of prostatic lymph nodes visualized on spiral computed tomography with three-dimensional reconstructionBJU INTERNATIONAL, Issue 1 2002C. Brössner Objective To evaluate the involvement of sacral lymph nodes in prostatic lymphatic drainage, using contemporary radiological imaging techniques. Patients and methods The study included six patients (mean age 61.8 years, range 51,75) with suspected prostate cancer. First, an oil-based contrast medium was injected into the prostate under transrectal ultrasonographic and fluoroscopic guidance, after which a standard ultrasound-guided sextant biopsy was taken. Before injecting the contrast medium, and 20 min and 24 h thereafter, the patients underwent spiral computed tomography of the pelvic region with three-dimensional reconstruction. Results In all patients the prostate drained via the sacral lymphatic region. Compared with the iliac lymphatic drainage system, there were fewer and narrower sacral lymph nodes. Prostatic sacral lymph nodes were located at S2 to S5, with an emphasis on S3,4. Lymph nodes were detected as presacral and in the sacral foramen, suggesting a direct lymphatic connection to the bony pelvis. Conclusion These results suggest that sacral prostatic lymphatics are a potential route of spread of prostate cancer cells. [source] The role of spatial scale and the perception of large-scale species-richness patternsECOLOGY LETTERS, Issue 2 2005Carsten Rahbek Abstract Despite two centuries of exploration, our understanding of factors determining the distribution of life on Earth is in many ways still in its infancy. Much of the disagreement about governing processes of variation in species richness may be the result of differences in our perception of species-richness patterns. Until recently, most studies of large-scale species-richness patterns assumed implicitly that patterns and mechanisms were scale invariant. Illustrated with examples and a quantitative analysis of published data on altitudinal gradients of species richness (n = 204), this review discusses how scale effects (extent and grain size) can influence our perception of patterns and processes. For example, a hump-shaped altitudinal species-richness pattern is the most typical (c. 50%), with a monotonic decreasing pattern (c. 25%) also frequently reported, but the relative distribution of patterns changes readily with spatial grain and extent. If we are to attribute relative impact to various factors influencing species richness and distribution and to decide at which point along a spatial and temporal continuum they act, we should not ask only how results vary as a function of scale but also search for consistent patterns in these scale effects. The review concludes with suggestions of potential routes for future analytical exploration of species-richness patterns. [source] The ,oestrogen hypothesis', where do we stand now?,INTERNATIONAL JOURNAL OF ANDROLOGY, Issue 1 2003Richard M. Sharpe Summary The original ,oestrogen hypothesis' postulated that the apparent increase in human male reproductive developmental disorders (testis cancer, cryptorchidism, hypospadias, low sperm counts) might have occurred because of increased oestrogen exposure of the human foetus/neonate; five potential routes of exposure were considered. This review revisits this hypothesis in the light of the data to have emerged since 1993. It addresses whether there is a secular increasing trend in the listed disorders and highlights the limitations of available data and how these are being addressed. It considers whether new data has emerged to support the suggestion that increased oestrogen exposure could cause these abnormalities and reviews new data on potential routes via which such increased exposure could have occurred. Secular trends: The disorders listed above are now considered to represent a syndrome of disorders (testicular dysgenesis syndrome, TDS) with a common origin in foetal life. Testicular cancer has increased in incidence in Caucasian men worldwide and lifetime risk is 0.3,0.8%. Secular trends in cryptorchidism are unclear but it is by far the commonest (2,4% at birth) congenital abnormality in either sex. Secular trends for hypospadias are not robust, although most studies suggest a progressive increase; registry data probably under-estimates incidence, but based on this data hypospadias is the second most common (0.3,0.7% at birth) congenital malformation. Retrospective analyses of sperm count data show a global downward trend but this is inconclusive , prospective studies using standardized methodology show significant differences between countries and very low sperm counts in the youngest cohort of men. For all disorders, other then testis cancer, standardized prospective studies are the best way forward and are in progress across Europe. Oestrogen effects: Evidence that foetal exposure to oestrogens can induce the above disorders has strengthened. New pathways via which such changes could be induced have been identified, including suppression of testosterone production by the foetal testis, suppression of androgen receptor expression and suppression of insulin-like factor-3 (InsL3) production by foetal Leydig cells. Other evidence suggests that the balance between androgen and oestrogen action may be important in induction of reproductive tract abnormalities. Oestrogen exposure: Although many new environmental oestrogens have been identified, their uniformly weak oestrogenicity excludes the possibility that they could induce the above disorders. However, emerging data implicates various environmental chemicals in being able to alter endogenous levels of androgens (certain phthalates) and oestrogens (polychlorinated biphenyls, polyhalogenated hydrocarbons), and the former have been shown to induce a similar collection of disorders to TDS. Other mechanisms via which increased fetal exposure to pregnancy oestrogens might occur (increasing trend in obesity, dietary changes) are also discussed. [source] Experiencing Globalization: Active Teaching and Learning in International Political EconomyINTERNATIONAL STUDIES PERSPECTIVES, Issue 1 2001Louise Amoore This article explores the teaching and learning challenges for the discipline of international studies (IS) that arise from the contemporary social, economic, and political changes usually labeled "globalization." The focus is upon the challenge posed to IS by a transformation in the nature of the relationship of teachers and students to the subject matter that they study: that is, teachers and students increasingly experience and contribute to globalization in the course of their daily lives as they simultaneously teach and learn about it. Significantly for the study of globalization in IS, pedagogical debates surrounding active teaching and learning highlight the potential for strategies that actively engage students' interests and everyday experiences with the subject itself. On this basis, the article outlines some potential routes into the active teaching and learning of globalization in the field of international political economy, illustrating these with examples from classroom activities and exercises. [source] The feasibility of developing a risk assessment for the impact of climate change on the emergence of Crimean-Congo haemorrhagic fever in livestock in Europe: a ReviewJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2010P. Gale Summary Crimean-Congo haemorrhagic fever virus (CCHFV) is one of the most widespread of all medically important arboviruses with ticks of the Hyalomma spp. serving as the main vectors. Infection of livestock by CCHFV serves as a route of exposure to humans, as a reservoir of disease and as a route of importation. This study discusses the pathways and data requirements for a qualitative risk assessment for the emergence of CCHFV in livestock in Europe. A risk map approach is proposed based on layers that include the potential routes of release (e.g. by migrating birds carrying infected ticks) together with the main components for exposure, namely the distributions of the tick vectors, the small vertebrate host reservoirs and the livestock. A layer on landscape fragmentation serves as a surrogate for proximity of livestock to the tick cycle. Although the impact of climate change on the emergence of CCHF is not clear, comparing the distribution of risk factors in each layer currently with those predicted in the 2080s with climate change can be used to speculate how potential high-risk areas may shift. According to the risk pathway, transstadial and/or transovarial transmission in the tick vector are crucial for CCHFV spread. Vector competence and tick vector switching, however, remain critical factors for CCHFV colonization of new regions in Europe. The species of migratory bird is also an important consideration in the release assessment with greater abundance and biodiversity of ground-dwelling birds in southern Europe than in northern Europe. [source] Can improvement in photosynthesis increase crop yields?PLANT CELL & ENVIRONMENT, Issue 3 2006STEPHEN P. LONG ABSTRACT The yield potential (Yp) of a grain crop is the seed mass per unit ground area obtained under optimum growing conditions without weeds, pests and diseases. It is determined by the product of the available light energy and by the genetically determined properties: efficiency of light capture (,i), the efficiency of conversion of the intercepted light into biomass (,c) and the proportion of biomass partitioned into grain (,). Plant breeding brings , and ,i close to their theoretical maxima, leaving ,c, primarily determined by photosynthesis, as the only remaining major prospect for improving Yp. Leaf photosynthetic rate, however, is poorly correlated with yield when different genotypes of a crop species are compared. This led to the viewpoint that improvement of leaf photosynthesis has little value for improving Yp. By contrast, the many recent experiments that compare the growth of a genotype in current and future projected elevated [CO2] environments show that increase in leaf photosynthesis is closely associated with similar increases in yield. Are there opportunities to achieve similar increases by genetic manipulation? Six potential routes of increasing ,c by improving photosynthetic efficiency were explored, ranging from altered canopy architecture to improved regeneration of the acceptor molecule for CO2. Collectively, these changes could improve ,c and, therefore, Yp by c. 50%. Because some changes could be achieved by transgenic technology, the time of the development of commercial cultivars could be considerably less than by conventional breeding and potentially, within 10,15 years. [source] | |||||||||||||||||||