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Surface Area (surface + area)
Kinds of Surface Area Terms modified by Surface Area Selected AbstractsThiobarbiturates as Sirtuin Inhibitors: Virtual Screening, Free-Energy Calculations, and Biological TestingCHEMMEDCHEM, Issue 12 2008Urszula Uciechowska Abstract NAD+ -dependent histone deacetylases (sirtuins) are enzymes that cleave acetyl groups from lysine residues in histones and other proteins. Potent selective sirtuin inhibitors are interesting tools for the investigation of the biological functions of these enzymes and may be future drugs for the treatment of cancer or neurodegenerative diseases. Herein we present the results from a protein-based virtual screen of a commercial database with subsequent biological testing of the most promising compounds. The combination of docking and in,vitro experimental testing resulted in the identification of novel sirtuin inhibitors with thiobarbiturate structure. To rationalize the experimental results, free-energy calculations were carried out by molecular mechanics Poisson,Boltzmann/surface area (MM-PBSA) calculations. A significant correlation between calculated binding free energies and measured Sirt2 inhibitory activities was observed. The analyses suggested a molecular basis for the interaction of the identified thiobarbiturate derivatives with human Sirt2. Based on the docking and MM-PBSA calculations we synthesized and tested five further thiobarbiturates. The MM-PBSA method correctly predicted the activity of the novel thiobarbiturates. The identified compounds will be used to further explore the therapeutic potential of sirtuin inhibitors. [source] METABOLIC AND ECOLOGICAL CONSTRAINTS IMPOSED BY SIMILAR RATES OF AMMONIUM AND NITRATE UPTAKE PER UNIT SURFACE AREA AT LOW SUBSTRATE CONCENTRATIONS IN MARINE PHYTOPLANKTON AND MACROALGAE,JOURNAL OF PHYCOLOGY, Issue 2 2007T. Alwyn Marine phytoplankton and macroalgae acquire important resources, such as inorganic nitrogen, from the surrounding seawater by uptake across their entire surface area. Rates of ammonium and nitrate uptake per unit surface area were remarkably similar for both marine phytoplankton and macroalgae at low external concentrations. At an external concentration of 1 ,M, the mean rate of nitrogen uptake was 10±2 nmol·cm,2·h,1 (n=36). There was a strong negative relationship between log surface area:volume (SA:V) quotient and log nitrogen content per cm2 of surface (slope=,0.77), but a positive relationship between log SA:V and log maximum specific growth rate (,max; slope=0.46). There was a strong negative relationship between log SA:V and log measured rate of ammonium assimilation per cm2 of surface, but the slope (,0.49) was steeper than that required to sustain ,max (,0.31). Calculated rates of ammonium assimilation required to sustain growth rates measured in natural populations were similar for both marine phytoplankton and macroalgae with an overall mean of 6.2±1.4 nmol·cm,2·h,1 (n=15). These values were similar to maximum rates of ammonium assimilation in phytoplankton with high SA:V, but the values for algae with low SA:V were substantially less than the maximum rate of ammonium assimilation. This suggests that the growth rates of both marine phytoplankton and macroalgae in nature are often constrained by rates of uptake and assimilation of nutrients per cm2 surface area. [source] Proximal Isovelocity Surface Area (PISA) in the Evaluation of Fixed Membranous Subaortic StenosisECHOCARDIOGRAPHY, Issue 2 2002Gregory M. Goodkin M.D. The evaluation of the severity of subaortic stenosis is usually expressed by the magnitude of the subvalvular gradient. Calculation of the membrane orifice area noninvasively is difficult by the standard means. We present a patient in whom the area was calculated using the proximal isovelocity surface area (PISA) method. This method should have clinical applicability because it is not flow dependent and can be used in patients with normal, reduced, or increased stroke volume. [source] In Vitro Validation of a New Approach for Quantitating Regurgitations Using Proximal Isovelocity Surface AreaECHOCARDIOGRAPHY, Issue 7 2000A. Delouche The present work has been designed to validate the calculation of the effective regurgitant orifice (ERO) area with the use of a new formula that takes into account the velocity profile (Vr vs r) and that is insensitive to errors in the determination of the position of the orifice. Assuming a hemispheric model, ERO = 2,r2· Vr/Vo (with Vo= velocity at the orifice) and (Vo/Vr)0.5= (2,/ERO)0.5r. Thus, the slope of the corresponding linear regression allows ERO to be calculated as: ERO = 2,/slope2. This approach was tested in vitro in pulsatile conditions on circular, conical, and slit-like orifices. The calculated ERO was compared with the actual jet cross sectional area derived from the transverse velocity profile at the jet origin. For the purpose of comparison, the "classical" ERO was calculated for all the configurations, angulations, and threshold velocities. The relationship between (Vo/Vr)0.5 was linear (r > 0.98) over a wide range of velocities. The nonhemispheric components were found to modify the constant and not the slope. The mean variation of the calculated ERO was 6.5%. The correlation between the calculated and the actual ERO was very close (>0.97) with slope equal to 0.96. By comparison with the new method, the classical formula gave an underestimation of the ERO that dramatically increased when studying the flow closer to the orifice or in the case of error on the measurement of r. In conclusion, a method using velocity profiles instead of isolated values improves the accuracy of the proximal isovelocity surface area (PISA) method for measuring the ERO. [source] The Effect of Surface Area and Crystal Structure on the Catalytic Efficiency of Iron(III) Oxide Nanoparticles in Hydrogen Peroxide DecompositionEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 16 2010Cenek Gregor Abstract Iron(II) oxalate dihydrate has been used as a readily decomposable substance for the controlled synthesis of nanosized iron(III) oxides. The polymorphous composition, particle size and surface area of these iron oxide nanoparticles were controlled by varying the reaction temperature between 185 and 500 °C. As-prepared samples were characterized by XRD, low-temperature and in-field Mössbauer spectroscopy, BET surface area and the TEM technique. They were also tested as heterogeneous catalysts in hydrogen peroxide decomposition. At the selected temperatures, the formed nanomaterials did not contain any traces of amorphous phase, which is known to considerably reduce the catalytic efficiency of iron(III) oxide catalysts. As the thickness of the sample (, 2 mm) was above the critical value, a temporary temperature increase ("exo effect") was observed during all quasi-isothermal decompositions studied, irrespective of the reaction temperature. Increasing the reaction temperature resulted in a shift of the exo effect towards shorter times and an increased content of maghemite phase. The maghemite content decreases above 350 °C as a result of a thermally induced polymorphous transition into hematite. The catalytic data demonstrate that the crystal structure of iron(III) oxide (i.e. the relative contents of maghemite and hematite) does not influence the rate of hydrogen peroxide decomposition. However, the rate constant increases monotonously with increasing sample surface area (and decreasing thermolysis temperature), reaching a maximum of 27,×,10,3 min,1(g/L),1 for the sample with a surface area of 285 m2,g,1. This rate constant is currently the highest reported value of all known iron oxide catalytic systems and is even slightly higher than that observed for the most efficient catalyst reported to date, which has a significantly larger surface area of 337 m2,g,1. This surprisingly high catalytic activity at relatively low surface area can be ascribed to the absence of a amorphous phase in the samples prepared in this study. Taking into account these new findings, the contributions of the key factors highlighted above (surface area, particle size, crystal structure, crystallinity) to the overall activity of iron oxides forhydrogen peroxide decomposition are discussed. [source] Compact and Light Supercapacitor Electrodes from a Surface-Only Solid by Opened Carbon Nanotubes with 2,200 m2 g,1 Surface AreaADVANCED FUNCTIONAL MATERIALS, Issue 3 2010Tatsuki Hiraoka Abstract An approach is presented to make a "surface-only solid" with a surface area of 2,240,m2 g,1 (1,310,m2,cm,3), corresponding to 85% of the atoms constituting a surface, by opening single-walled carbon nanotube forests and solids via controlled oxidation. The controllability of the approach is demonstrated by tailoring the hole size to match the guest molecule, for example, nitrogen, fullerene, or solvated ions. These features make the surface-only solid an ideal vessel for material and energy storage, as demonstrated by its use for electrodes to realize a light and compact supercapacitor with high energy (24.7,W h kg,1) and power (98.9,kW kg,1) densities, exceeding those of activated carbon (16.9,W h kg,1 and 35.7,kW kg,1). [source] The parameterization and validation of generalized born models using the pairwise descreening approximationJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 14 2004Julien Michel Abstract Generalized Born Surface Area (GBSA) models for water using the Pairwise Descreening Approximation (PDA) have been parameterized by two different methods. The first method, similar to that used in previously reported parameterizations, optimizes all parameters against the experimental free energies of hydration of organic molecules. The second method optimizes the PDA parameters to compensate only for systematic errors of the PDA. The best models are compared to Poisson,Boltzmann calculations and applied to the computation of potentials of mean force (PMFs) for the association of various molecules. PMFs present a more rigorous test of the ability of a solvation model to correctly reproduce the screening of intermolecular interactions by the solvent, than its accuracy at predicting free energies of hydration of small molecules. Models derived with the first method are sometimes shown to fail to compute accurate potentials of mean force because of large errors in the computation of Born radii, while no such difficulties are observed with the second method. Furthermore, accurate computation of the Born radii appears to be more important than good agreement with experimental free energies of solvation. We discuss the source of errors in the potentials of mean force and suggest means to reduce them. Our findings suggest that Generalized Born models that use the Pairwise Descreening Approximation and that are derived solely by unconstrained optimization of parameters against free energies of hydration should be applied to the modeling of intermolecular interactions with caution. © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 1760,1770, 2004 [source] Novel Method for Obtaining Corundum Layers of High Surface Area on Ceramic Supports for High-Temperature CatalysisJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2002Alejandro Souto The surface of an aluminosilicate ceramic was transformed to a corundum layer of high specific surface area by heating at 1300°,1450°C in a controlled reducing atmosphere. This procedure selectively reduced and volatilized the silica of the glass and mullite, and the alumina of the mullite formed a layer of corundum crystals with a thickness of ,20 ,m and a specific surface area of ,16 m2/g. Specific surface area remained stable at 10.5 m2/g after prolonged heating at 1300°C in air, and at 8.5 m2/g at 1450°C. These materials are well suited for use as catalyst supports in applications such as catalytic combustion at temperatures in this range. [source] Valganciclovir Dosing According to Body Surface Area and Renal Function in Pediatric Solid Organ Transplant RecipientsAMERICAN JOURNAL OF TRANSPLANTATION, Issue 3 2009W. Vaudry Oral valganciclovir is effective prophylaxis for cytomegalovirus (CMV) disease in adults receiving solid organ transplantation (SOT). However, data in pediatrics are limited. This study evaluated the pharmacokinetics and safety of valganciclovir oral solution or tablets in 63 pediatric SOT recipients at risk of CMV disease, including 17 recipients ,2 years old. Patients received up to 100 days' valganciclovir prophylaxis; dosage was calculated using the algorithm: dose (mg) = 7 × body surface area × creatinine clearance (Schwartz method; CrCLS). Ganciclovir pharmacokinetics were described using a population pharmacokinetic approach. Safety endpoints were measured up to week 26. Mean estimated ganciclovir exposures showed no clear relationship to either body size or renal function, indicating that the dosing algorithm adequately accounted for both these variables. Mean ganciclovir exposures, across age groups and organ recipient groups were: kidney 51.8 ± 11.9 ,g * h/mL; liver 61.7 ± 29.5 ,g * h/mL; heart 58.0 ± 21.8 ,g * h/mL. Treatment was well tolerated, with a safety profile similar to that in adults. Seven serious treatment-related adverse events (AEs) occurred in five patients. Two patients had CMV viremia during treatment but none experienced CMV disease. In conclusion, a valganciclovir-dosing algorithm that adjusted for body surface area and renal function provides ganciclovir exposures similar to those established as safe and effective in adults [source] Targeted Synthesis of a Porous Aromatic Framework with High Stability and Exceptionally High Surface Area,ANGEWANDTE CHEMIE, Issue 50 2009Teng Ben Diamantenfieber: Ein Diamantgerüst, in dem C-C-Bindungen gegen Benzolringe ausgetauscht sind (siehe Bild), ist einerseits stabil und hat andererseits eine große innere Oberfläche. Das poröse aromatische Gerüst PAF-1 (Oberfläche 7100,m2,g,1) kann große Mengen an Wasserstoff und Kohlendioxid, Benzol- und Toluoldampf aufnehmen. [source] Nondestructive, Stereological Estimation of Canopy Surface AreaBIOMETRICS, Issue 1 2010Dvoralai Wulfsohn Summary We describe a stereological procedure to estimate the total leaf surface area of a plant canopy in vivo, and address the problem of how to predict the variance of the corresponding estimator. The procedure involves three nested systematic uniform random sampling stages: (i) selection of plants from a canopy using the,smooth fractionator, (ii) sampling of leaves from the selected plants using the,fractionator, and (iii) area estimation of the sampled leaves using,point counting. We apply this procedure to estimate the total area of a chrysanthemum (Chrysanthemum morifolium L.) canopy and evaluate both the time required and the precision of the estimator. Furthermore, we compare the precision of point counting for three different grid intensities with that of several standard leaf area measurement techniques. Results showed that the precision of the plant leaf area estimator based on point counting is high. Using a grid intensity of 1.76 cm2/point we estimated plant and canopy surface areas with accuracies similar to or better than those obtained using image analysis and a commercial leaf area meter. For canopy surface areas of approximately 1 m2 (10 plants), the fractionator leaf approach with sampling fraction equal to 1/9 followed by point counting using a 4.3 cm2/point grid produced a coefficient of error of less than 7%. The,smooth fractionator,can be used to ensure that the additional contribution to the estimator variance due to between-plant variability is small. [source] Calculation of the Evolution of Surface Area and Free Volume During the Infiltration of Fiber Felts,CHEMICAL VAPOR DEPOSITION, Issue 12 2007A. Pfrang Abstract The evolution of surface area and free volume during the infiltration of fiber felts is calculated quantitatively and compared with experimental data. For overlapping fibers the evolution is approximated by a Boolean model, where the ratio of surface area to free volume increases linearly with the radius of the fibers. For randomly distributed fibers which do not overlap in the initial state, the evolution of surface area and free volume is calculated numerically. The surface area/free volume ratio increases nearly linearly for all initial filling factors and for all degrees of orientation anisotropy of the fibers. [source] High Surface Area, Mesoporous, Glassy Alumina with a Controllable Pore Size by Nanocasting from Carbon AerogelsCHEMISTRY - A EUROPEAN JOURNAL, Issue 5 2005Wen-Cui Li Dr. Abstract A strategy to synthesize amorphous, mesoporous alumina by nanocasting has been developed, involving carbon aerogel as a hard template and aluminum nitrate solution as an alumina precursor. The alumina generated exhibits small, transparent granules with a 3,6 mm diameter and has inherited the three-dimensional network structure of the carbon template. The mesopore surface area of the alumina can be as high as 365 m2,g,1, and the pore volume reaches 1.55 cm3,g,1 after calcination at 600,°C in air for 8 h. The pore parameters can be varied within a certain range by variation of the carbon aerogel template and the loading amount of the alumina precursor. At high loadings, the obtained glassy alumina clearly has a bimodal pore size distribution in the mesopore range. [source] Direct Measurement of Size, Three-Dimensional Shape, and Specific Surface Area of Anatase NanocrystalsCHEMPHYSCHEM, Issue 6 2007Armin Feldhoff Dr. Little is different: The specific surface areas of individual crystal facets on anatase nanocrystals (see picture) are estimated quantitatively by the combination of transmission electron microscope measurements with a Wulff-type construction of the three-dimensional shape. The results demonstrate that the crystal facets that are most abundant for macroscopic crystals are not necessarily those that predominate in nanocrystals. [source] Mesoporous Anatase TiO2 Beads with High Surface Areas and Controllable Pore Sizes: A Superior Candidate for High-Performance Dye-Sensitized Solar CellsADVANCED MATERIALS, Issue 21 2009Dehong Chen Mesoporous anatase TiO2 beads with high surface areas and controllable pore sizes are prepared by using a combined sol,gel and solvothermal process. Dye-sensitized solar cells made from these mesoporous beads gave a total power conversion efficiency of 7.20% under AM 1.5 sunlight, higher than that obtained using Degussa P25 films of similar thickness (5.66%). [source] ChemInform Abstract: Facile Method to Synthesize Mesoporous Multimetal Oxides (ATiO3, A: Sr, Ba) with Large Specific Surface Areas and Crystalline Pore Walls.CHEMINFORM, Issue 32 2010Xiaoxing Fan Abstract Mesoporous SrTiO3 and BaTiO3 are prepared based on the evaporation-induced self-assembly approach using in-situ inorganic pore-makers (carbonate). [source] Local,regional boundary shifts in oribatid mite (Acari: Oribatida) communities: species,area relationships in arboreal habitat islands of a coastal temperate rain forest, Vancouver Island, CanadaJOURNAL OF BIOGEOGRAPHY, Issue 9 2007Zoë Lindo Abstract Aim, This study investigates the species,area relationship (SAR) for oribatid mite communities of isolated suspended soil habitats, and compares the shape and slope of the SAR with a nested data set collected over three spatial scales (core, patch and tree level). We investigate whether scale dependence is exhibited in the nested sampling design, use multivariate regression models to elucidate factors affecting richness and abundance patterns, and ask whether the community composition of oribatid mites changes in suspended soil patches of different sizes. Location, Walbran Valley, Vancouver Island, Canada. Methods, A total of 216 core samples were collected from 72 small, medium and large isolated suspended soil habitats in six western redcedar trees in June 2005. The relationship between oribatid species richness and habitat volume was modelled for suspended soil habitat isolates (type 3) and a nested sampling design (type 1) over multiple spatial scales. Nonlinear estimation parameterized linear, power and Weibull function regression models for both SAR designs, and these were assessed for best fit using R2 and Akaike's information criteria (,AIC) values. Factors affecting oribatid mite species richness and standardized abundance (number per g dry weight) were analysed by anova and linear regression models. Results, Sixty-seven species of oribatid mites were identified from 9064 adult specimens. Surface area and moisture content of suspended soils contributed to the variation in species richness, while overall oribatid mite abundance was explained by moisture and depth. A power-law function best described the isolate SAR (S = 3.97 × A0.12, R2 = 0.247, F1,70 = 22.450, P < 0.001), although linear and Weibull functions were also valid models. Oribatid mite species richness in nested samples closely fitted a power-law model (S = 1.96 × A0.39, R2 = 0.854, F1,18 = 2693.6, P < 0.001). The nested SAR constructed over spatial scales of core, patch and tree levels proved to be scale-independent. Main conclusions, Unique microhabitats provided by well developed suspended soil accumulations are a habitat template responsible for the diversity of canopy oribatid mites. Species,area relationships of isolate vs. nested species richness data differed in the rate of accumulation of species with increased area. We suggest that colonization history, stability of suspended soil environments, and structural habitat complexity at local and regional scales are major determinants of arboreal oribatid mite species richness. [source] Gravimetric method to find internal surface of macroporous silicon membranesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2007A. A. Nechitailov Abstract A simple method to evaluate the internal surface area, porosity, pore diameter and pore density of macroporous silicon membranes has been proposed and tested. The porosity p is obtained from the mass loss under anodizing, and the surface area per unit volume Sv is determined from the mass of SiO2 formed on the pore surface as a result of thermal oxidation. The average pore diameter d and pore density N can be easily calculated from the obtained Sv and p. Experimental verification of d and N was performed by means of SEM and optical microscope images; Sv was checked by BET technique. Surface area and porosity on the resistivity of initial n-Si in the range , = 3,25 Ohm · cm have been studied for the samples with regular and self-organized macropore "lattices". The obtained values are within the limits p = 27,50%, Sv = 2800,6000 cm2/cm3, d = 1.9,6.5 ,m, N = 1.4,10 × 106 cm,2, and in a good agreement with the data of microscopic characterization. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Thermal processing of biomass natural fibre wastes by pyrolysisINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 2 2004Anton R. Reed Abstract Waste biomass material in the form of natural fibres used in the production of textile products were examined for their potential to produce activated carbon by physical activation. The five biomass types were hemp, flax, jute, coir and abaca. Each biomass was pyrolysed in a fixed bed reactor and the char characterized. The char was subsequently, activated with steam in a char activation reactor. The surface area and porosity of the derived activated carbon was determined. Surface areas of between 770 and 879 m2 g,1 were achieved. The yield of activated carbon was mostly less than 20 wt% of the original biomass. The five biomass samples were also pyrolysed in a thermogravimetric analyser. The thermal degradation of the biomas samples were discussed in terms of the thermal degradation of the main components of the biomass, cellulose, hemicellulose and lignin. Copyright © 2004 John Wiley & Sons, Ltd. [source] Cell-specific elevation of NRF2 and sulfiredoxin-1 as markers of oxidative stress in the lungs of idiopathic pulmonary fibrosis and non-specific interstitial pneumoniaAPMIS, Issue 9 2010WITOLD MAZUR Mazur W, Lindholm P, Vuorinen K, Myllärniemi M, Salmenkivi K, Kinnula VL. Cell-specific elevation of NRF2 and sulfiredoxin-1 as markers of oxidative stress in the lungs of idiopathic pulmonary fibrosis and non-specific interstitial pneumonia. APMIS 2010; 118: 703,12. Human idiopathic pulmonary fibrosis (IPF) and non-specific interstitial pneumonia (NSIP) have been proposed to be attributable to oxidative stress. The nuclear factor, erythroid derived 2, like protein (NRF2),sulfiredoxin-1 (SRX1) pathway was hypothesized to be associated with the pathogenesis of human pulmonary fibrosis. Several methods including digital morphometry were used in the assessment of the cell-specific localization and expression of NRF2 and SRX1 and selected proteins linked to their activation/stability in human IPF/usual interstitial pneumonia (UIP) and NSIP lung. The proteins of the NRF2 pathway were localized in the hyperplastic alveolar epithelium and inflammatory cells in IPF and NSIP, but were absent in the fibroblastic foci characteristic of IPF. Morphometric evaluation revealed NRF2 and KEAP1 to be significantly elevated in the hyperplastic alveolar epithelium compared with the normal alveolar epithelium, and NRF2 was remarkably expressed in the nuclear compartment of the hyperplastic cells. SRX1 was expressed mainly in alveolar macrophages, and the number of SRX1-positive macrophages/surface area was elevated in NSIP, a disease which contains more marked inflammatory reaction compared with the IPF/UIP lung. The expression of the NRF2 pathway in human IPF and NSIP is further evidence that the pathogenesis of human fibrotic lung diseases is oxidant-mediated and originates from the alveolar epithelium. [source] Lazy Solid Texture SynthesisCOMPUTER GRAPHICS FORUM, Issue 4 2008Yue Dong Abstract Existing solid texture synthesis algorithms generate a full volume of color content from a set of 2D example images. We introduce a new algorithm with the unique ability to restrict synthesis to a subset of the voxels, while enforcing spatial determinism. This is especially useful when texturing objects, since only a thick layer around the surface needs to be synthesized. A major difficulty lies in reducing the dependency chain of neighborhood matching, so that each voxel only depends on a small number of other voxels. Our key idea is to synthesize a volume from a set of pre-computed 3D candidates, each being a triple of interleaved 2D neighborhoods. We present an efficient algorithm to carefully select in a pre-process only those candidates forming consistent triples. This significantly reduces the search space during subsequent synthesis. The result is a new parallel, spatially deterministic solid texture synthesis algorithm which runs efficiently on the GPU. Our approach generates high resolution solid textures on surfaces within seconds. Memory usage and synthesis time only depend on the output textured surface area. The GPU implementation of our method rapidly synthesizes new textures for the surfaces appearing when interactively breaking or cutting objects. [source] Application for regenerative medicine of epithelial cell culture-vistas of cultured epitheliumCONGENITAL ANOMALIES, Issue 3 2006Hajime Inoue ABSTRACT This review describes culture techniques for the epithelial system as well as trends in the clinical application of cultured keratinocytes in our department and the possibility of applying the techniques to other organs. Cultured epithelium and cultured dermis in particular have considerably preceded regeneration of other organs in the field of regenerative medicine. Since 1988 we have grafted cultured keratinocytes by the Rheinwald-Green modified method in at least 500 patients with large skin defects. As a result of the establishment of a culture technique for individual patients, it is now possible to prepare enough regenerated epithelium to cover the body surface area of as many as 10 adult patients in approximately three weeks after collecting 1 cm2 of skin, and then remaining cultured keratinocytes can be cryo-preserved for two-stage dermatoplasty at another site. This procedure makes it possible to avoid frequent skin collection from the same patient and thereby improves patients' quality of life and activities of daily living. On the other hand, to solve the problem of regenerated epithelium shrinking and problems with graft efficiency on dermis defect lesion, we have developed a proteinase-resistant regenerated dermis by mixing a certain protein with a fibrin scaffold. Recently we also took the initiative in grafting hybrid-type regenerated trachea in an animal experiment by using the epithelial and dermal cell culture technique, and some results of the graft were obtained. [source] Synthesis of highly-ordered hierarchical ZnO nanostructures and their application in dye-sensitized solar cellsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2010Y. F. Zhu Abstract In order to improve the performance of ZnO-based solar cells, highly-ordered hierarchical ZnO nanostructures were design and fabricated. The hierarchical nanostructures were grown on FTO (fluorine doped tin oxide, SnO2:F) glass substrates via a facile, low-temperature, and low-cost chemical route. The morphology and structure of the obtained products has been confirmed by field-emission scanning electron microscopy and X-ray diffraction measurements. The performance investigation of the prepared dye-sensitized solar cells (DSSCs) demonstrates that the hierarchical ZnO nanostructure-based solar cell shows a higher short-circuit current density compared with the ZnO nanowire counterpart. The enhanced current density may be due to the fact that the surface area of the hierarchical nanostructures is increased. These results indicate that hierarchical ZnO nanostructures are more suitable for the application as photoelectrode of DSSCs. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Bulk growth of gallium nitride: challenges and difficultiesCRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2007M. Bockowski Abstract The present status of the GaN bulk growth by High Pressure Solution (HPS) method and combination of HPS and Hydride Vapor Phase Epitaxy (HVPE) methods is reviewed. Up to now the spontaneous high pressure solution growth of GaN results in crystals having habit of hexagonal platelets of surface area of 3 cm2 or needles with length up to 1 cm. Recently, the platelets and needles have been used as seeds for the HVPE growth. On the other hand, the LPE technique under pressure with pressure-grown GaN (hp-GaN), GaN/sapphire template, patterned GaN/sapphire template and free standing HVPE GaN as seeds has been examined and developed. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A CRITICAL LOOK AT PAP ADEQUECY: ARE OUR CRITERIA SATISFACTORY?CYTOPATHOLOGY, Issue 2006D.R. Bolick Liquid based Pap (LBP) specimen adequacy is a highly documented, yet poorly understood cornerstone of our GYN cytology practice. Each day, as cytology professionals, we make adequacy assessments and seldom wonder how the criteria we use were established. Are the criteria appropriate? Are they safe? What is the scientific data that support them? Were they clinically and statistically tested or refined to achieve optimal patient care? In this presentation, we will take a fresh look at what we know about Pap specimen adequacy and challenge some of the core assumptions of our daily practice. LBP tests have a consistent, well-defined surface area for screening, facilitating the quantitative estimates of slide cellularity. This provides an unprecedented opportunity to establish reproducible adequacy standards that can be subjected to scientific scrutiny and rigorous statistical analysis. Capitalizing on this opportunity, the TBS2001 took the landmark step to define specimen adequacy quantitatively, and set the threshold for a satisfactory LBP at greater than 5,000 well visualized squamous epithelial cells. To date, few published studies have attempted to evaluate the validity or receiver operator characteristics for this threshold, define an optimal threshold for clinical utility or assess risks of detection failure in ,satisfactory' but relatively hypocellular Pap specimens. Five years of cumulative adequacy and cellularity data of prospectively collected Pap samples from the author's laboratory will be presented, which will serve as a foundation for a discussion on ,Pap failure'. A relationship between cellularity and detection of HSIL will be presented. Risk levels for Pap failure will be presented for Pap samples of different cellularities. The effect of different cellularity criterion on unsatisfactory Pap rates and Pap failure rates will be demonstrated. Results from this data set raise serious questions as to the safety of current TBS2001 adequacy guidelines and suggest that the risk of Pap failure in specimens with 5,000 to 20 000 squamous cells on the slide is significantly higher than those assumed by the current criteria. TBS2001 designated all LBP to have the same adequacy criterion. Up to this point, it has been assumed that ThinPrep, SurePath, or any other LBP would be sufficiently similar that they should have the same adequacy criteria. Data for squamous cellularity and other performance characteristics of ThinPrep and SurePath from the author's laboratory will be compared. Intriguing data involving the recently approved MonoPrep Pap Test will be reviewed. MonoPrep clinical trial data show the unexpected finding of a strong correlation between abundance of endocervical component and the detection of high-grade lesions, provoking an inquiry of a potential new role for a quantitative assessment of the transition zone component. The current science of LBP adequacy criteria is underdeveloped and does not appear to be founded on statistically valid methods. This condition calls us forward as a body of practitioners and scientists to rigorously explore, clarify and define the fundamental nature of cytology adequacy. As we forge this emerging science, we will improve diagnostic performance, guide the development of future technologies, and better serve the patients who give us their trust. Reference:, Birdsong GG: Pap smear adequacy: Is our understanding satisfactory? Diagn Cytopathol. 2001 Feb; 24(2): 79,81. [source] Anisotropic contraction in forisomes: Simple models won't fitCYTOSKELETON, Issue 5 2008Winfried S. Peters Abstract Forisomes are ATP-independent, Ca2+ -driven contractile protein bodies acting as reversible valves in the phloem of plants of the legume family. Forisome contraction is anisotropic, as shrinkage in length is associated with radial expansion and vice versa. To test the hypothesis that changes in length and width are causally related, we monitored Ca2+ - and pH-dependent deformations in the exceptionally large forisomes of Canavalia gladiata by high-speed photography, and computed time-courses of derived geometric parameters (including volume and surface area). Soybean forisomes, which in the resting state resemble those of Canavalia geometrically but have less than 2% of the volume, were also studied to identify size effects. Calcium induced sixfold volume increases in forisomes of both species; in soybean, responses were completed in 0.15 s, compared to about 0.5 s required for a rapid response in Canavalia followed by slow swelling for several minutes. This size-dependent behavior supports the idea that forisome contractility might rest on similar mechanisms as those of polyelectrolyte gels, a class of artificial "smart" materials. In both species, time-courses of forisome length and diameter were variable and lacked correlation, arguing against a simple causal relationship between changes in length and width. Moreover, changes in the geometry of soybean forisomes differed qualitatively between Ca2+ - and pH-responses, suggesting that divalent cations and protons target different sites on the forisome proteins. Cell Motil. Cytoskeleton 2008. © 2008 Wiley-Liss, Inc. [source] The effect of combined simulated microgravity and microgrooved surface topography on fibroblastsCYTOSKELETON, Issue 3 2007W. A. Loesberg Abstract This study evaluated in vitro the differences in morphological behaviour between fibroblast cultured on smooth and microgrooved substrata (groove depth: 0.5 ,m, width: 1, 2, 5, and 10 ,m), which were subjected to simulated microgravity. The aim of the study was to clarify which of these parameters was more dominant to determine cell behaviour. Morphological characteristics were investigated using scanning electron microscopy and fluorescence microscopy in order to obtain qualitative information on cell alignment and area. Confocal laser scanning microscopy visualised distribution of actin filaments and focal adhesion points. Finally, expression of collagen type I, fibronectin, and ,1- and ,1-integrin were investigated by PCR. Microscopy and image analysis showed that the fibroblasts aligned along the groove direction on all textured surfaces. On the smooth substrata, cells had spread out in a random fashion. The alignment of cells cultured on grooved surfaces decreased under simulated microgravity, especially after 24 h of culturing. Cell surface area on grooved substrata were significantly smaller than on smooth substrata, but simulated microgravity on the grooved groups resulted in an enlargement of cell area. ANOVA was performed on all main parameters: topography, gravity force, and time. In this analysis, all parameters proved significant. In addition, gene levels were reduced by microgravity particularly those of ,1-integrin and fibronectin. From our data it is concluded that the fibroblasts primarily adjust their shape according to morphological environmental cues like substratum surface whilst a secondary, but significant, role is played by microgravity conditions. Cell Motil. Cytoskeleton 2007. © 2007 Wiley-Liss, Inc. [source] Changes in capillary luminal diameter in rat soleus muscle after hind-limb suspensionACTA PHYSIOLOGICA, Issue 4 2000Kano This study examined the time course change of the capillary luminal diameter and the number of capillaries in the rat soleus muscle during hind-limb suspension. Male Wistar rats were divided into 1 and 3 weeks of hind-limb suspension (HS) groups (HS-1 and HS-3). The HS groups were compared with age-matched control groups. All morphometric parameters with respect to capillary and muscle fibre cross-sectional area were determined in perfusion-fixed soleus muscles. After 1 and 3 weeks of hind-limb suspension, the mean muscle fibre cross-sectional area was significantly decreased in HS-1 (,32.0%) and HS-3 (,59.3%) compared with age-matched control groups. Despite a lower capillary-to-fibre ratio (HS-1, ,19.3%; HS-3, ,21.2%), the capillary density was unchanged in HS-1 and significantly increased in HS-3 compared with age-matched control groups. The mean capillary luminal diameter was significantly smaller in HS-1 (,19.9%) and HS-3 (,21.9%) than in the age-matched control groups. The capillary-to-fibre perimeter ratio which indicates the capillary surface area available for gas exchange between blood and tissue did not significantly differ between control groups and HS groups. In conclusion, the morphometrical adaptations in rat soleus with the suspension involved changes in both the capillary luminal diameter and number of capillaries, and the change in capillary surface area was proportional to the degree of muscle atrophy in HS groups. [source] Change in supporting tissue following loss of a permanent maxillary incisor in childrenDENTAL TRAUMATOLOGY, Issue 6 2007Helen D. Rodd Abstract,,, Alveolar bone resorption is an inevitable consequence of tooth loss and may be detrimental to long-term dental aesthetics and function. The aim of the present study was to quantify the degree of tissue resorption following the loss of a permanent incisor in a young population. The study group comprised 11 boys and five girls who all required the extraction of a permanent maxillary central incisor due to trauma-related sequelae. Mean age at tooth loss was 10.8 years. Upper alginate impressions were taken at regular intervals following tooth loss and were cast in yellow dental stone. Study models were sectioned longitudinally through the mid-point of both the maxillary incisor socket and the contra-lateral incisor to provide a thin plaster section. Digital photographs were acquired of the edentulous (A1) and dentate (A2) surfaces of this section and image analysis software was employed to quantify the surface area of both A1 and A2. At 3 months postextraction, mean A1 was 15.7% less than mean A2. By 6 months mean A1 had further reduced and was 25.3% less than that of the corresponding dentate alveolus. However, at subsequent time intervals following tooth extraction (>6 months), tissue loss appeared to stabilise with an overall reduction in tissue area remaining at 22%. This reduction in supporting tissue area was found to be highly statistically significant (P = 0.002, anova). Furthermore, girls appeared to have an overall greater degree of tissue loss than boys (P = 0.015). Further research is indicated to explore factors influencing the degree of tissue loss following incisor extraction and the benefit of therapeutic interventions in limiting this resorption. [source] Longitudinal Diminution of Tumor Size for Basal Cell Carcinoma Suggests Shifting Referral Patterns for Mohs SurgeryDERMATOLOGIC SURGERY, Issue 1 2008ANDREW L. KAPLAN MD BACKGROUND The Mohs technique for removal of cutaneous malignancies offers tissue-sparing benefits compared with other treatment methods. With wider acceptance and availability of Mohs surgery, referral patterns may be shifting toward the treatment of smaller, lower-risk tumors. OBJECTIVE The objective was to examine whether referral patterns for basal cell carcinoma (BCC) at an academic Mohs surgery practice have shifted over recent years toward referral for smaller, lower risk tumors. METHODS A retrospective longitudinal comparison of tumor characteristics was performed for BCCs treated at our institution from a recent year (2004) and a past year (1996). Statistical analyses were used to identify differences in tumor size, distribution by anatomic site, and primary versus recurrent status. RESULTS Complete data were available for 603 BCCs treated in 1996 and 1,514 BCCs treated in 2004. A 24% decrease in preoperative tumor surface area was observed from 1996 (1.25 cm2) to 2004 (0.95 cm2). Tumors were twice as likely to be recurrent in 1996 (15.1%) than in 2004 (7.4%). There were no significant differences in the anatomic distribution of lesions in the years compared. CONCLUSIONS Findings at our institution suggest that in recent years, referral patterns have shifted toward a preference for Mohs surgery for the treatment of smaller, primary BCCs. This may be a result of increased awareness by the dermatologic and medical community of the numerous advantages of Mohs surgery and a greater appreciation of its tissue-sparing properties, which may result in less complex and more successful aesthetic reconstructions. [source] | ||||||||||||||||||||||||||||||||||||||||||||||