Home About us Contact
|
Home About us Contact | ||
|
|
||
Irregular Shape (irregular + shape)
Selected AbstractsQuasi-two-dimensional electrodeposition growth of Pb0.5Sn0.5 alloyCRYSTAL RESEARCH AND TECHNOLOGY, Issue 5 2006Bin Sun Abstract Electrodeposition of Pb0.5Sn0.5 alloy is carried out in a quasi-2D electrochemical cell. As the growth proceeds the morphologies of the deposits transit from cake-like to branched and finally to the compact morphology. We show that these morphological transitions arise from the changes in the transport mechanisms of the ions in the electrolyte cell. In addition, it is found that the current density on the growth interface can vary spontaneously due to the irregular shape of the deposit and the generation of hydrogen gas. It causes the formation of the complex microstructure with non-uniform composition. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Regression of Atypical Nevus: An Anecdotal Dermoscopic ObservationDERMATOLOGIC SURGERY, Issue 10 2006MARIA A PIZZICHETTA MD BACKGROUND Clark nevi (atypical melanocytic nevi) can be considered as risk markers and potential precursors of melanoma. The authors report on the morphologic changes of an atypical nevus by dermoscopic follow-up examination over a 7-year period. CASE REPORT A 43-year-old man had a brown macule on his back, sized 5 mm, with an irregular shape, clinically and dermoscopically diagnosed as an equivocal melanocytic lesion. Dermoscopically during the initial examination, a predominant reticular pattern with peripheral eccentric hyperpigmentation in the lower portion of the lesion could be seen. After 7 months, the area of peripheral eccentric hyperpigmentation had regressed, and after 4.5 years the atypical pigment network had almost disappeared. After 7 years of follow-up, a diffuse area of hypopigmentation and a residual light brown pigmentation were detectable. The histopathologic diagnosis was consistent with an atypical junctional nevus with regression with features of a Clark nevus. CONCLUSION Based on our observation, even a dermoscopically atypical nevus may undergo regression as documented by long-term dermoscopic follow-up. [source] Channels, wetlands and islands in the Okavango Delta, Botswana, and their relation to hydrological and sedimentological processesEARTH SURFACE PROCESSES AND LANDFORMS, Issue 1 2004T. Gumbricht Abstract The Okavango wetland in northern Botswana is one of the world's largest inland deltas. The delta is a dynamic environment with shifting channel routes, causing growth and decay of ,anking wetlands, and giving birth to islands. Primary island nuclei are formed by ,uvial processes and bioengineering, and subsequently grow into secondary larger islands of irregular shape by clastic and chemical sedimentation, and later by coalescence. This article presents classi,cations and quantitative estimations of channels, wetlands and islands of the Okavango Delta. Islands were classi,ed dependent on composition, pattern of composition, shape and juxtaposition. 90 per cent of all islands in the entire wetland were identi,ed, with a classi,cation accuracy of 60 to 85 per cent. Smaller islands of the nucleus types dominate the upper parts of the delta, whereas larger secondary islands are more common in the distal part, a re,ection of the age of the islands. Islands in the entry valley of the delta, the Panhandle, are larger in the top end , the primary region of recent clastic sedimentation. The overall size distribution of islands in the delta, however, shows no clumps, indicating that island growth is a uniform process over time and space. The total area ,ooded at least every decade is approximately 14 000 km2, of which 9000 km2 is classi,ed as actual wetland. Channel meandering decreases from the Panhandle to the distal part of the delta, with the abandoned Thaoge channel as an exception. Occurrence of ,uvially formed islands in the distal delta indicates that the water ,ow and area of inundation must once have been much larger. Copyright © 2004 John Wiley & Sons, Ltd. [source] AMP-activated protein kinase deficiency exacerbates aging-induced myocardial contractile dysfunctionAGING CELL, Issue 4 2010Subat Turdi Summary Aging is associated with myocardial dysfunction although the underlying mechanism is unclear. AMPK, a key cellular fuel sensor for energy metabolism, is compromised with aging. This study examined the role of AMPK deficiency in aging-associated myocardial dysfunction. Young or old wild-type (WT) and transgenic mice with overexpression of a mutant AMPK ,2 subunit (kinase dead, KD) were used. AMPK , isoform activity, myocardial function and morphology were examined. DCF and JC-1 fluorescence probes were employed to quantify reactive oxygen species (ROS) and mitochondrial membrane potential (,,m), respectively. KD mice displayed significantly reduced ,2 but not ,1 AMPK isoform activity at both ages with a greater effect at old age. Aging itself decreased ,1 isoform activity. Cardiomyocyte contractile function, intracellular Ca2+ handling, and SERCA2a levels were compromised with aging, the effects of which were exacerbated by AMPK deficiency. H&E staining revealed cardiomyocyte hypertrophy with aging, which was more pronounced in KD mice. TEM micrographs displayed severe disruption of mitochondrial ultrastructure characterized by swollen, irregular shape and disrupted cristae in aged KD compared with WT mice. Aging enhanced ROS production and reduced ,,m, the effects of which were accentuated by AMPK deficiency. Immunoblotting data depicted unchanged Akt phosphorylation and a significant decrease in mitochondrial biogenesis cofactor PGC-1, in aged groups. AMPK deficiency but not aging decreased the phosphorylation of ACC and eNOS. Expression of membrane Glut4 and HSP90 was decreased in aged KD mice. Moreover, treatment of the AMPK activator metformin attenuated aging-induced cardiomyocyte contractile defects. Collectively, our data suggest a role for AMPK deficiency in aging-induced cardiac dysfunction possibly through disrupted mitochondrial function and ROS production. [source] Extending point pattern analysis for objects of finite size and irregular shapeJOURNAL OF ECOLOGY, Issue 4 2006THORSTEN WIEGAND Summary 1We use a grid- and simulation-based approach to extend point pattern analysis to deal with plants of finite size and irregular shape, and compare the results of our approach with that of the conventional point approximation. The plants are approximated by using an underlying grid and may occupy several adjacent grid cells depending on their size and shape. Null models correspond to that of point pattern analysis but need to be modified to account for the finite size and irregular shape of plants. 2We use a mapped area of a grass-shrub steppe in semi-arid Patagonia, Argentina, to show that the shrub community is essentially randomly structured, but that shrubs facilitate grasses in their immediate neighbourhood. 3The occurrence of this random spatial structure provides important new information on the biology of shrub populations. In general, previous data from semi-arid and arid ecosystems have shown that adult shrubs tend to show over-dispersed patterns, whereas juveniles are clumped. 4We find that the point approximation may produce misleading results (i) if plant size varies greatly, (ii) if the scale of interest is of the same order of magnitude as the size of the plants, and (iii) if the plants of a given pattern are constrained through competition for space by the presence of other plants. The point approximation worked well in all other cases, but usually depicted weaker significant effects than when the size and shape of plants were taken into account. 5Our approach to quantifying small-scale spatial patterns in plant communities has broad applications, including the study of facilitation and competition. Ecologists will be able to use the software available to take advantage of these methods. [source] Wet granulation as innovative and fast method to prepare controlled release granules based on an ion-exchange resinJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 3 2008Beatrice Albertini Abstract The goal of this work was to evaluate the suitability of wet granulation as an innovative and fast method for the preparation of granules containing a drug,resin complex (resinate), having cholestyramine as resin and potassium diclofenac (KD) as drug. Resinate and granules were prepared directly by steam granulation in high shear mixer (method A), using two different amount of resin (granules 1 and 2). For comparison granules 1 were also prepared by conventional batch method followed by steam granulation (method B). All granules showed quite irregular shape, main size fractions between 75 and 500 µm, good flowability and uniform KD distribution. Granules 1A exhibited controlled release profiles at pH 7.4, while granules 2A showed a burst effect due to KD free crystals. FT-IR studies confirmed the complete complexation between resin and KD during the granulation process with method A for granules 1. Finally, the dissolution test of granules 1A in different media revealed a controlled drug release in 12 h, providing the utility of this system for enteric drug delivery. Granules 1B evidenced similar characteristics to those of granules 1A; the drawback of the multistep procedure was related to the long processing time. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:1313,1324, 2008 [source] The effect of water to ethanol feed ratio on physical properties and aerosolization behavior of spray dried cromolyn sodium particlesJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 5 2005Kambiz Gilani Abstract Cromolyn sodium (CS) was spray dried under constant operation conditions from different water to ethanol feed ratios (50:50,0:100). The spray dried CS samples were characterized for their physicochemical properties including crystallinity, particle size distribution, morphology, density, and water/ethanol content. To determine quantitatively the crystallinity of the powders, an X-ray diffraction (XRD) method was developed using samples with different crystallinity prepared by physical mixing of 100% amorphous and 100% crystalline CS materials. The aerodynamic behavior of the CS samples was determined using an Andersen Cascade Impactor (ACI) with a Spinhaler® at an air flow of 60 L/min. Binary mixtures of each spray dried CS powder and Pharmatose® 325, a commercial ,-lactose monohydrate available for DPI formulations, were prepared and in vitro aerosol deposition of the drug from the mixtures was analyzed using ACI to evaluate the effect of carrier on deposition profiles of the spray dried samples. CS spray dried from absolute ethanol exhibited XRD pattern characteristic for crystalline materials and different from patterns of the other samples. The crystallinity of spray dried CS obtained in the presence of water varied from 0% to 28.37%, depending on the ratio of water to ethanol in the feed suspensions. All samples presented different particle size, water/ethanol content, and bulk density values. CS particles spray dried from absolute ethanol presented uniform elongated shape whereas the other samples consisted mainly of particles with irregular shape. Overall, fine particle fraction increased significantly (p,<,0.01) with decreasing d50% and water and ethanol content of spray dried CS samples. Significant difference (p,<,0.01) in deposition profiles of the drug were observed between corresponding carrier free and carrier blended formulations. The difference in deposition profiles of CS aerosolized from various spray dried samples were described according to the particle size, shape, and water/ethanol contents of the powders. The results of this study indicate that enhanced aerosol performance of CS can be obtained by spray drying of the drug from suspensions containing ,87.5% v/v ethanol. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:1048,1059, 2005 [source] Hybrid Dirichlet mixture models for functional dataJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES B (STATISTICAL METHODOLOGY), Issue 4 2009Sonia Petrone Summary., In functional data analysis, curves or surfaces are observed, up to measurement error, at a finite set of locations, for, say, a sample of n individuals. Often, the curves are homogeneous, except perhaps for individual-specific regions that provide heterogeneous behaviour (e.g. ,damaged' areas of irregular shape on an otherwise smooth surface). Motivated by applications with functional data of this nature, we propose a Bayesian mixture model, with the aim of dimension reduction, by representing the sample of n curves through a smaller set of canonical curves. We propose a novel prior on the space of probability measures for a random curve which extends the popular Dirichlet priors by allowing local clustering: non-homogeneous portions of a curve can be allocated to different clusters and the n individual curves can be represented as recombinations (hybrids) of a few canonical curves. More precisely, the prior proposed envisions a conceptual hidden factor with k -levels that acts locally on each curve. We discuss several models incorporating this prior and illustrate its performance with simulated and real data sets. We examine theoretical properties of the proposed finite hybrid Dirichlet mixtures, specifically, their behaviour as the number of the mixture components goes to , and their connection with Dirichlet process mixtures. [source] MRT Letter: Spatial distribution of vancomycin-induced damage in Staphylococcus epidermidis biofilm: An electron microscopic studyMICROSCOPY RESEARCH AND TECHNIQUE, Issue 7 2010Rachna Singh Abstract This study was planned to elucidate the efficacy of antibiotics on Staphylococcus epidermidis and Staphylococcus aureus biofilms by scanning electron microscopy (SEM). Biofilms of S. epidermidis ATCC 35984 and S. aureus ATCC 29213 were grown on black, polycarbonate membranes placed on tryptic soy agar plates for 48 h at 37°C, and then exposed to vancomycin or amikacin or ciprofloxacin at clinically achievable levels for 24 h at 37°C. The morphology of antibiotic-treated and untreated biofilms was elucidated by SEM. SEM analysis indicated a differential affection of S. epidermidis ATCC 35984 in the center and periphery of biofilm upon treatment with vancomycin. The center of biofilm revealed damaged cells with sparse distribution, smaller size, and irregular shape, whereas cells in the periphery were unaffected. This differential distribution of susceptibility within S. epidermidis ATCC 35984 biofilms was specific for vancomycin only and was not observed on exposure to amikacin or ciprofloxacin. No such response was found in S.aureus ATCC 29213 biofilms. Thus, our study suggests a spatial distribution of vancomycin-induced damage in S. epidermidis biofilms. To our knowledge, this is the first report that indicates a differential affection of S. epidermidis in the center and periphery of biofilm upon treatment with vancomycin. Studies on the factors controlling this differential distribution could provide valuable insights into the mechanisms of antimicrobial resistance in S. epidermidis biofilms. Microsc. Res. Tech., 2010. © 2010 Wiley-Liss, Inc. [source] Relative viscosity models and their application to capillary flow data of highly filled hard-metal carbide powder compoundsPOLYMER COMPOSITES, Issue 1 2005Tomas Honek The rheological behavior of highly filled polymer systems used in powder injection molding (PIM) technology strongly influences the final properties of the products. In this study, the capillary flow data of multi-component polymer binders,based on polyethylene, paraffin, ethylene-based copolymers, and polyethylene glycol,compounded with three various hard-metal carbide powders were employed. The rheology of such highly filled (up to 50 vol%) multiphase systems is necessarily a complex phenomenon characterized by strain dependent, non-Newtonian properties complicated by flow instabilities and yield. Over 15 mathematical models proposed for highly filled systems were tested, some of them calculating the maximum filler loading. Due to the complex structure of the filler (irregular shape, particle size distribution) and a multi-component character of the binder, the applicability of these models varied with the powder-binder systems studied. However, the particular values of maximum loadings are in good accordance with the predictions based on powder characteristics. Simple modification of Frankel-Acrivos model to the systems containing unimodal hard-metal carbide powders with particles of an irregular shape and broad particle size distribution gave precise agreement between experimental data and model prediction. POLYM. COMPOS., 26:29,36, 2005. © 2004 Society of Plastics Engineers. [source] Morphology development of PC/PE blends during compounding in a twin-screw extruderPOLYMER ENGINEERING & SCIENCE, Issue 1 2007Bo Yin The morphological development of a polycarbonate/polyethylene (PC/PE) blend in a twin-screw extruder was studied using a scanning electron microscope (SEM). The effects of extrusion temperature, viscosity ratio (the ratio of the viscosity of the dispersed phase to that of the matrix), and the screw configuration on the morphology of the PC/PE blend during the extrusion were discussed in detail. It was found that the morphology of the dispersed particles and the interfacial adhesion between the dispersed phase and matrix were both influenced by the extrusion temperature. The dispersed phase had a spheroidal shape and a small size during the high temperature processing, and an irregular shape and a large size when it was processed at low temperature. The PC phase with a lower viscosity was easier to disperse and also to coalesce. Therefore, the deformation of the low-viscosity dispersed phase during the processing was more intense than that of the high-viscosity dispersed phase. By comparing the effects of the different screw configurations on the morphology development of the PC/PE blend, it was found that the melting and breaking up of the dispersed phase were mainly affected in the initial blending stages by the number of the kneading blocks. While a kneading block with a 90 degree staggering angle was used, the size of the dispersed particles decreased and the long fibers were shortened, the large particles were drawn by the additional kneading zone. Finally, all of these structures were completely changed to the short fibers. POLYM. ENG. SCI., 47:14,25, 2007. © 2006 Society of Plastics Engineers [source] Investigation of mechanism of Al(OH)3 crystal growthTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2009I. Nikoli Abstract Crystallization of Al(OH)3 that occurs during the decomposition of caustic soda solutions is an important part of Bayer process for alumina production. Several phenomena, which influence the physicochemical characteristics of precipitated Al(OH)3, occur simultaneously during this process. They are nucleation, agglomeration, and crystal growth of Al(OH)3. In this article, we have investigated the mechanism of Al(OH)3 crystal growth from pure caustic soda solutions and in the presence of oxalic acid. The results have shown that the growth of Al(OH)3 crystals from caustic soda solutions follow the B,+,S model (birth and spread). New Al(OH)3 particles, formed during the decomposition process of pure caustic soda solutions, are characterized by regular hexagonal shape. The nuclei have the same geometry as the contact face. However, microstructural investigations of Al(OH)3 samples, obtained by crystallization from caustic soda solutions in the presence of oxalic acid, have shown the presence of nuclei of irregular shape in addition to regular ones. So, the presence of oxalic acid in the caustic soda solutions leads to a change in crystal habit. Besides, the results obtained by kinetic investigation confirmed the mentioned mechanism of Al(OH)3 crystal growth. La cristallisation de l'Al(OH)3 qui accompagne la décomposition de solutions de soude caustique est une caractéristique importante du procédé Bayer de production d'alumine. Plusieurs phénomènes influant sur les caractéristiques physicochimiques de l'Al(OH)3 précipité, se produisent simultanément lors de ce procédé. Ce sont la nucléation, l'agglomération et la croissance des cristaux de l'Al(OH)3. Dans cet article, nous avons étudié le mécanisme de croissance des cristaux de l'Al(OH)3 à partir de solutions de soude caustique pures et en présence d'acide oxalique. Les résultats montrent que la croissance des cristaux d'Al(OH)3 à partir des solutions de soude caustique suit le modèle B,+,S (naissance (birth),+,dispersion (spread)). Les nouvelles particules d'Al(OH)3, formées lors du procédé de décomposition des solutions de soude caustique, se caractérisent par une forme hexagonale régulière. Les nuclei ont la même géométrie que la face de contact. Cependant, des recherches sur la microstructure des échantillons d'Al(OH)3 obtenus par cristallisation à partir des solutions de soude caustique en présence d'acide oxalique, montrent la présence de nuclei de forme irrégulière en plus de ceux de forme régulière. Ainsi, la présence d'acide oxalique dans les solutions de soude caustique mène à un changement dans le comportement des cristaux. En outre, les résultats obtenus dans l'étude cinétique confirment ce mécanisme de croissance des cristaux d'Al(OH)3. [source] Performance of Dual-Media Expanded Bed BioreactorASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5-6 2005R. Abdul-Rahman Abstract Adsorption and biological treatment are two possible approaches to remove chloro-organic and organic compounds. Granular activated carbon (GAC) biofilm reactors combine these two features, the adsorptive capacity and irregular shape of GAC particles providing niches for bacterial colonisation protected from high fluid forces, while the variety of functional groups on the surface enhance the attachment of microorganisms. The biofilm process is compact and offers reactions in both aerobic and anoxic states. Studies on removal of nitrogen constituents by a biofilm process were carried out using a dual-media expanded bed bioreactor, with GAC and plastic media as support media. The plastic media also acts as a filter for the effluent. Experiments were carried out at F:M of about 0.45 and hydraulic residence times (HRT) of 48, 24 and 12 hours. Bed expansion was maintained at 20,30% by recirculation flow. Aerobic condition was maintained at dissolved oxygen (DO) of about 2 mg/l throughout the bed. Chemical oxygen in demand (COD) in feed was 1000 mg/L while the total-N was 100 mg/L. Analysis showed that the process is able to maintain very stable conditions, achieving substantial COD removal of about 85% and total-N removal of about 80%. Biofilm biomass measurements showed an increase from 400 mg/l at HRT of 48 hours to 10,100 mg/l at HRT 12 hours, showing that much higher biomass concentrations may be contained in a biofilm process as compared to a conventional suspended biomass process. Bioreactors contain their own ecosystems, the nature of the community and the state of microorganisms define the kinetics and determine reactor performance. Growth kinetic parameters obtained are YH = 0.3421 mg/mg, m,H = 0.2252 day,1, KH = 319.364 mg/l and bH = 0.046 day,1. The denitrification kinetic parameters obtained are YHD = 0.9409 mg/mg, m,HD = 0.1612 day,1, KHD = 24.6253 mg/l and bHD = 0.0248 day,1. These parameters enable prediction of required reactor sizes and operational parameters. The plastic media has greatly improved effluent clarification by 98% as compared to single-media (GAC) only reactor. [source] Forest landscape pattern in the KwaZulu,Natal midlands, South Africa: 50 years of change or stasis?AUSTRAL ECOLOGY, Issue 6 2004MICHAEL J. LAWES Abstract Understanding patterns and processes of habitat change is essential for managing and conserving forest fragments in anthropogenically altered landscapes. Digitized aerial photographs from 1944 and 1996 were examined for changes to the indigenous forest landscape in the Karkloof-Balgowan archipelago in KwaZulu,Natal, South Africa. Attributes relating to proximate land-use, patch shape, isolation and position in the landscape were used to determine putative causes of forest change. The total change in forest area was ,5.7% (forest covered 6739 ha in 1996). This is contrasted with previous reports for the period 1880,1940 that estimated change in total forest area of up to ,80%. Attrition was the predominant process of forest transformation between 1944 and 1996. Despite little overall change in forest area, 786 mostly small (<0.5 ha) forest patches were lost from the landscape, leaving 1277 forest patches in 1996. An increase in patch isolation, but no change in patch cohesion accompanied the changes in forest area. Ignoring patches that were eliminated, 514 patches decreased in area. This was partly a function of patch size, but the conversion of natural grassland to commercial plantation forestry in the matrix also influenced forest decline. Their small size and irregular shape caused forest patches in the region to be vulnerable to edge effects. Core area declined in a negative exponential way with increasing edge width and the total area of edge habitat exceeded that of core habitat at an edge width of only 50 m. Nevertheless, total core area decreased by only 2% (65 ha) between 1944 and 1996 because most of the eliminated patches were small and contained no core area. The large Karkloof forest (1649 ha) is a conservation priority for forest interior species, but the ecological role and biodiversity value of small forest patches should not be overlooked. [source] Eye shape and peripheral visual field recording in high myopia at approximately 54 years of age, as based on ultrasonography and Goldmann kinetic perimetryACTA OPHTHALMOLOGICA, Issue 5 2010Hans C. Fledelius Abstract. Purpose:, This study describes the posterior pole contour and visual field (VF) findings in an unselected series of adults (aged approximately 54 years) with high myopia. Methods:, In 1962, 39 14-year-old teenagers with myopia of , 6 D, in one or both eyes, were identified in a 1948 Copenhagen birth cohort (n = 9243). At a follow-up in 2002, 61 eyes (52 with high myopia and nine fellow eyes; n = 31 subjects) were examined by ultrasound B-scan, to allow: (a) measurement of the axial vitreous length supplementary to the customary axial A-scan, and (b) assessment of the posterior pole contour of the eye. Further, the large-object (V, 4e) kinetic Goldmann perimetry isoptre was recorded to outline the ambulatory VF. Results:, An irregular posterior pole contour was observed in 15 eyes, unilaterally in 11 eyes and bilaterally in four (two subjects). Nasal fundus ectasia was suggested in six and other deviations from the sphere in seven subjects. Kinetic Goldmann perimetry showed marginal restriction in 14 eyes (12 subjects). Larger defects were found in four eyes (three subjects); the corresponding axial lengths exceeded 32 mm in the two subjects with unilateral defects, and symmetrical inferior binasal defects, probably unrelated to the myopia, were found in the bilateral subject. Conclusions:, Unselected adult-age high myopia mainly presented with a regular eye shape that was close to spherical. An irregular shape suggesting posterior staphyloma was seen in 13 of the 32 subjects under study, mainly unilaterally. No subjects were restricted in everyday activities by VF defects. Marginal Goldmann perimetry restrictions were described in 12 and significant defects in three subjects. Generally, longer eyes more often tended to show irregular posterior eye contours and/or VF defects. [source] Effect of Interparticle Potential on Forming Solid, Spherical Agglomerates during DryingJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2004Geoff E. Fair The effect of the interparticle potential on the shapes of the agglomerates obtained by drying slurry droplets has been investigated using aqueous alumina slurries formulated in the dispersed and weakly attractive (dispersed + added salt) states. For the dispersed slurry, the droplets dried to irregular shapes with hollow centers. When just the right amount of salt was added to produce an attractive, but nontouching, particle network, the droplets dried as solid spheres. These results are discussed by relating both the nature of the particle network (repulsive or weakly attractive), the slurry rheology, and the consolidation mechanics of the networks to the requirements for maintaining a spherical geometry and uniform density during droplet drying. [source] Highly Efficient Visible Light Plasmonic Photocatalyst Ag@Ag(Br,I)CHEMISTRY - A EUROPEAN JOURNAL, Issue 33 2010Peng Wang Abstract The new plasmonic photocatalyst Ag@Ag(Br,I) was synthesized by the ion-exchange process between the silver bromide and potassium iodide, then by reducing some Ag+ ions in the surface region of Ag(Br,I) particles to Ag0 species. Ag nanoparticles are formed from Ag(Br,I) by the light-induced chemical reduction reaction. The Ag@Ag(Br,I) particles have irregular shapes with their sizes varying from 83,nm to 1,,m. The as-grown plasmonic photocatalyst shows strong absorption in the visible light region because of the plasmon resonance of Ag nanoparticles. The ability of this compound to reduce CrVI under visible light was compared with those of other reference photocatalyst. The plasmonic photocatalyst is shown to be highly efficient under visible light. The stability of the photocatalyst was examined by X-ray diffraction and X-ray photoelectron spectroscopy. The XRD pattern and XPS spectra prove the stability of the plasmonic photocatalyst Ag@Ag(Br,I). [source] | |||||||||||||||||||