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Sample records for prepared rapid gradient

  1. Preparation of gradient polyacrylate brushes in microchannels.

    Science.gov (United States)

    Lee, Seongyeol; Youm, Sang Gil; Song, Yeari; Yi, Whikum; Sohn, Daewon

    2012-05-01

    Gradient poly(2-hydroxyethyl methacrylate) brushes were synthesized by surface-initiated atom transfer radical polymerization (ATRP) confined within a microfluidic system on a silicon wafer. For ATRP, surface initiator, 11-((2-bromo, 2-methyl) propionyloxy) undecyltrichlorosilane (BUC), was synthesized, and allowed to self-assemble in a monolayer on the Si wafer, as analyzed by XPS to confirm the presence of an ester group of BUC. A solution containing 2-hydroxyethylmethacrylate, Cu catalyst, and bipyridin was allowed to flow in a microchannel and polymerize, resulting in the brushes with a gradient of thickness on the Si wafer. Using ellipsometry and ATR-IR, we verified the gradients of well established brushes on the Si wafer. AFM and contact angle data showed that wettability of the brushes did not exhibit a linear relationship with hydrophilicity.

  2. Rapid cortical dynamics associated with auditory spatial attention gradients

    Directory of Open Access Journals (Sweden)

    Jeffrey Ryan Mock

    2015-06-01

    Full Text Available Behavioral and EEG studies suggest spatial attention is allocated as a gradient in which processing benefits decrease away from an attended location. Yet the spatiotemporal dynamics of cortical processes that contribute to attentional gradients are unclear. We measured EEG while participants (n=35 performed an auditory spatial attention task that required button press to sounds at one target location on either the left or right. Distractor sounds were randomly presented at four non-target locations evenly spaced up to 180° from the target location. Attentional gradients were quantified by regressing ERP amplitudes elicited by distractors against their spatial location relative to the target. Independent component analysis was applied to each subject’s scalp channel data, allowing isolation of distinct cortical sources. Results from scalp ERPs showed a tri-phasic response with gradient slope peaks at ~300 ms (frontal, positive, ~430 ms (posterior, negative, and a plateau starting at ~550 ms (frontal, positive. Corresponding to the first slope peak, a positive gradient was found within a central component when attending to both target locations and for two lateral frontal components when contralateral to the target location. Similarly, a central posterior component had a negative gradient that corresponded to the second slope peak regardless of target location. A right posterior component had both an ipsilateral followed by a contralateral gradient. Lateral posterior clusters also had decreases in α and β oscillatory power with a negative slope and contralateral tuning. Only the left posterior component (120-200 ms corresponded to absolute sound location. Results characterize a rapid, temporally-organized sequence of gradients thought to reflect interplay between frontal and parietal regions. We conclude these gradients support a target-based saliency map exhibiting aspects of both right-hemisphere dominance and opponent process models.

  3. Rapid cortical dynamics associated with auditory spatial attention gradients.

    Science.gov (United States)

    Mock, Jeffrey R; Seay, Michael J; Charney, Danielle R; Holmes, John L; Golob, Edward J

    2015-01-01

    Behavioral and EEG studies suggest spatial attention is allocated as a gradient in which processing benefits decrease away from an attended location. Yet the spatiotemporal dynamics of cortical processes that contribute to attentional gradients are unclear. We measured EEG while participants (n = 35) performed an auditory spatial attention task that required a button press to sounds at one target location on either the left or right. Distractor sounds were randomly presented at four non-target locations evenly spaced up to 180° from the target location. Attentional gradients were quantified by regressing ERP amplitudes elicited by distractors against their spatial location relative to the target. Independent component analysis was applied to each subject's scalp channel data, allowing isolation of distinct cortical sources. Results from scalp ERPs showed a tri-phasic response with gradient slope peaks at ~300 ms (frontal, positive), ~430 ms (posterior, negative), and a plateau starting at ~550 ms (frontal, positive). Corresponding to the first slope peak, a positive gradient was found within a central component when attending to both target locations and for two lateral frontal components when contralateral to the target location. Similarly, a central posterior component had a negative gradient that corresponded to the second slope peak regardless of target location. A right posterior component had both an ipsilateral followed by a contralateral gradient. Lateral posterior clusters also had decreases in α and β oscillatory power with a negative slope and contralateral tuning. Only the left posterior component (120-200 ms) corresponded to absolute sound location. The findings indicate a rapid, temporally-organized sequence of gradients thought to reflect interplay between frontal and parietal regions. We conclude these gradients support a target-based saliency map exhibiting aspects of both right-hemisphere dominance and opponent process models.

  4. Rapid (ten-minute) pore-gradient electrophoresis of proteins and peptides in Micrograd gels.

    Science.gov (United States)

    Wrigley, C W; Margolis, J

    1992-01-01

    Precast gradient gels of short migration length (25 mm) have been developed to provide rapid electrophoretic separation without loss of resolution. These Micrograd gels have been prepared in gel ranges (conventional and unique) to match pore-gradient electrophoresis conditions to proteins/peptides ranging in size from several hundreds to millions. The Hylinx Micrograd gel combines an extreme gel range (6 to 48% polyacrylamide) with a novel crosslinker to provide sieving of polypeptides, and pore-limit electrophoresis of the smallest proteins (e.g. insulin monomer). All gel ranges (such as 3 to 30%) provide zone sharpening in routine analysis of conventional protein mixtures (e.g. serum) within 10 min electrophoresis at 200 to 300 volts. The gels are thin (1 mm) and thus stain quickly, but the gel cassette is of conventional overall width (83 mm), thus fitting many apparatus designs and accommodating 12 samples. The gels are finding valuable use in screening applications, requiring the electrophoretic analysis of many samples, and in cases where a rapid answer is needed, such as monitoring protein purification. The gels have proved particularly useful, in-house, for the latter application in developing Gradipore's new large-scale preparative electrophoresis system, the Gradiflow.

  5. Magnetization transfer prepared gradient echo MRI for CEST imaging.

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    Zhuozhi Dai

    Full Text Available Chemical exchange saturation transfer (CEST is an emerging MRI contrast mechanism that is capable of noninvasively imaging dilute CEST agents and local properties such as pH and temperature, augmenting the routine MRI methods. However, the routine CEST MRI includes a long RF saturation pulse followed by fast image readout, which is associated with high specific absorption rate and limited spatial resolution. In addition, echo planar imaging (EPI-based fast image readout is prone to image distortion, particularly severe at high field. To address these limitations, we evaluated magnetization transfer (MT prepared gradient echo (GRE MRI for CEST imaging. We proved the feasibility using numerical simulations and experiments in vitro and in vivo. Then we optimized the sequence by serially evaluating the effects of the number of saturation steps, MT saturation power (B1, GRE readout flip angle (FA, and repetition time (TR upon the CEST MRI, and further demonstrated the endogenous amide proton CEST imaging in rats brains (n = 5 that underwent permanent middle cerebral artery occlusion. The CEST images can identify ischemic lesions in the first 3 hours after occlusion. In summary, our study demonstrated that the readily available MT-prepared GRE MRI, if optimized, is CEST-sensitive and remains promising for translational CEST imaging.

  6. Gradient ascent pulse engineering for rapid exchange saturation transfer

    Science.gov (United States)

    Rancan, G.; Nguyen, T. T.; Glaser, S. J.

    2015-03-01

    Efforts in the clinical translation of the paraCEST contrast agent Yb-HPDO3A have prompted an investigation into saturation pulse optimality under energy constraints. The GRAPE algorithm has been adapted and implemented for saturation pulse optimization with chemical exchange. The flexibility of the methodology, both in extracting the microscopical parameter ensemble for the algorithm as well as in determining the characteristics of this new class of rising amplitude waveforms allows rapid testing and implementation. Optimal pulses achieve higher saturation efficiencies than the continuous wave gold standard for rapid and especially for variable exchange rates, as brought about by pH-catalysis. Gains of at least 5-15% without any tradeoff have been confirmed both on a spectrometer and on a clinical imager. Pool specific solutions, with pulses optimized for a specific exchange rate value, additionally increase the flexibility of the CEST ratiometric analysis. A simple experimental approach to determine close to optimal triangular pulses is presented.

  7. Gradient Elution Moving Boundary Electrophoresis Enables Rapid Analysis of Acids in Complex Biomass-Derived Streams

    Energy Technology Data Exchange (ETDEWEB)

    Munson, Matthew S.; Karp, Eric M.; Nimlos, Claire T.; Salit, Marc; Beckham, Gregg T.

    2016-12-05

    Biomass conversion processes such as pretreatment, liquefaction, and pyrolysis often produce complex mixtures of intermediates that are a substantial challenge to analyze rapidly and reliably. To characterize these streams more comprehensively and efficiently, new techniques are needed to track species through biomass deconstruction and conversion processes. Here, we present the application of an emerging analytical method, gradient elution moving boundary electrophoresis (GEMBE), to quantify a suite of acids in a complex, biomass-derived streams from alkaline pretreatment of corn stover. GEMBE offers distinct advantages over common chromatography-spectrometry analytical approaches in terms of analysis time, sample preparation requirements, and cost of equipment. As demonstrated here, GEMBE is able to track 17 distinct compounds (oxalate, formate, succinate, malate, acetate, glycolate, protocatechuate, 3-hydroxypropanoate, lactate, glycerate, 2-hydroxybutanoate, 4-hydroxybenzoate, vanillate, p-coumarate, ferulate, sinapate, and acetovanillone). The lower limit of detection was compound dependent and ranged between 0.9 and 3.5 umol/L. Results from GEMBE were similar to recent results from an orthogonal method based on GCxGC-TOF/MS. Overall, GEMBE offers a rapid, robust approach to analyze complex biomass-derived samples, and given the ease and convenience of deployment, may offer an analytical solution for online tracking of multiple types of biomass streams.

  8. Protein adsorption on gradient surfaces on polyethylene prepared in a shielded gas plasma

    NARCIS (Netherlands)

    Spijker, Hendrikje; Bos, Roelof; van Oeveren, Willem; de Vries, Jacob; Busscher, Hendrik

    1999-01-01

    In this study, a new and simple method is described to prepare wettability gradients on polymers by means of glow discharge in a partly shielded argon plasma. The surface characteristics of thus prepared gradients on low density polyethylene were determined by contact angle measurements and electron

  9. A rapid and scalable density gradient purification method for Plasmodium sporozoites

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    Kennedy Mark

    2012-12-01

    Full Text Available Abstract Background Malaria remains a major human health problem, with no licensed vaccine currently available. Malaria infections initiate when infectious Plasmodium sporozoites are transmitted by Anopheline mosquitoes during their blood meal. Investigations of the malaria sporozoite are, therefore, of clear medical importance. However, sporozoites can only be produced in and isolated from mosquitoes, and their isolation results in large amounts of accompanying mosquito debris and contaminating microbes. Methods Here is described a discontinuous density gradient purification method for Plasmodium sporozoites that maintains parasite infectivity in vitro and in vivo and greatly reduces mosquito and microbial contaminants. Results This method provides clear advantages over previous approaches: it is rapid, requires no serum components, and can be scaled to purify >107 sporozoites with minimal operator involvement. Moreover, it can be effectively applied to both human (Plasmodium falciparum, Plasmodium vivax and rodent (Plasmodium yoelii infective species with excellent recovery rates. Conclusions This novel method effectively purifies viable malaria sporozoites by greatly reducing contaminating mosquito debris and microbial burdens associated with parasite isolation. Large-scale preparations of purified sporozoites will allow for enhanced in vitro infections, proteomics, and biochemical characterizations. In conjunction with aseptic mosquito rearing techniques, this purification technique will also support production of live attenuated sporozoites for vaccination.

  10. Quantum state preparation in semiconductor dots by adiabatic rapid passage

    OpenAIRE

    Wu, Yanwen; Piper, I.M.; Ediger, M.; Brereton, P.; Schmidgall, E. R.; Hugues, M.; Hopkinson, M.; Phillips, R.T.

    2010-01-01

    Preparation of a specific quantum state is a required step for a variety of proposed practical uses of quantum dynamics. We report an experimental demonstration of optical quantum state preparation in a semiconductor quantum dot with electrical readout, which contrasts with earlier work based on Rabi flopping in that the method is robust with respect to variation in the optical coupling. We use adiabatic rapid passage, which is capable of inverting single dots to a specified upper level. We d...

  11. Preparation of biocompatible structural gradient coatings on pure titanium

    Institute of Scientific and Technical Information of China (English)

    TANG Guang-xin; ZHANG Ren-ji; YAN Yong-nian

    2004-01-01

    In order to overcome the poor osteo-inductive properties of titanium implant, some methods have been used. The efforts to improve implant biocompatibility and durability by applying a hybrid technique of composite oxidation (pre-anodic and micro-arc oxidation) and hydrothermal treatment were described. Pure titanium was used as the substrate material. An oxalic acid was used as the electrolyte for the pre-anodic oxidation. A calcium and phosphate salt solution was acted as the electrolyte of micro-arc oxidation and the common pure water was used for hydrothermal treatment. X-ray diffraction (XRD), and scanning electron microscopy (SEM) have been used to investigate the microstructure and morphology of the coatings. The results show that a compact TiO2 film can be made by pre-anodic oxidation, which is effective as chemical barriers against the in-vivo release of metal ions from the implants. A porous TiO2 coating can be produced by micro-arc oxidation on titanium plate, which is beneficial to bone tissue growth and enhancing anchorage of implant to bone. De-calcium HA can be formed on the coating using hydrothermal treatment, which is similar with the primary component of bone and has a very good osteo-inductivity.The porous gradient titania coating made by the hybrid oxidation and hydrothermal treatment should show good biocompatibility in the environment of the human body.

  12. Study of preparation of BG/HA gradient coating on titanium alloy by electrophoretic deposition method

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiao-ming; HAN Qing-rong; LI Shi-pu; XU Chuan-bo

    2001-01-01

    In this paper, a gradient bioactive coating made from modified bioglass (BG) and hydroxyapatite (HA) was prepared by electrophoretic deposition method(EPD)on the surface of titanium alloy. Strong bonding between the matrix and BG/HA gradient coating was got by sintering. Crystal composition of the coating was analyzed by XRD. The characteristics of surface and cross section of the coating were observed by SEM. Adhesive strength of the coating was tested by pull method. The optimizing technological parameters were determined.

  13. Preparation and characterization of chemical gradient surfaces and their application for the study of cellular interaction phenomena

    NARCIS (Netherlands)

    Ruardy, TG; Schakenraad, JM; vanderMei, HC; Busscher, HJ

    1997-01-01

    Chemical gradient surfaces are surfaces with a gradually changing chemistry along their length which is responsible for a position bound variation in physical properties, most notably, the wettability. In this review, methods to prepare (palladium deposition, diffusion technique, density gradient

  14. Preparing silica aerogel monoliths via a rapid supercritical extraction method.

    Science.gov (United States)

    Carroll, Mary K; Anderson, Ann M; Gorka, Caroline A

    2014-02-28

    A procedure for the fabrication of monolithic silica aerogels in eight hours or less via a rapid supercritical extraction process is described. The procedure requires 15-20 min of preparation time, during which a liquid precursor mixture is prepared and poured into wells of a metal mold that is placed between the platens of a hydraulic hot press, followed by several hours of processing within the hot press. The precursor solution consists of a 1.0:12.0:3.6:3.5 x 10(-3) molar ratio of tetramethylorthosilicate (TMOS):methanol:water:ammonia. In each well of the mold, a porous silica sol-gel matrix forms. As the temperature of the mold and its contents is increased, the pressure within the mold rises. After the temperature/pressure conditions surpass the supercritical point for the solvent within the pores of the matrix (in this case, a methanol/water mixture), the supercritical fluid is released, and monolithic aerogel remains within the wells of the mold. With the mold used in this procedure, cylindrical monoliths of 2.2 cm diameter and 1.9 cm height are produced. Aerogels formed by this rapid method have comparable properties (low bulk and skeletal density, high surface area, mesoporous morphology) to those prepared by other methods that involve either additional reaction steps or solvent extractions (lengthier processes that generate more chemical waste).The rapid supercritical extraction method can also be applied to the fabrication of aerogels based on other precursor recipes.

  15. Rapid evolution of drug resistance of multiple myeloma in the microenvironment with drug gradients

    Science.gov (United States)

    Wu, Amy; Zhang, Qiucen; Lambert, Guillaume; Khin, Zayar; Silva, Ariosto; Gatenby, Robert; Kim, John; Pourmand, Nader; Austin, Robert; Sturm, James

    2013-03-01

    Drug resistance in cancer is usually caused by the spatial drug gradients in tumor environment. Here, we culture multiple myeloma in a gradient from 0 to 20 nM of doxorubicin (genotoxic drug) across 2 mm wide region for 12 days. The myeloma cells grew rapidly and formed 3D colonies in the regions with less drug concentration. However, we have seen emergent colonies forming in regions with drug concentration above the minimal inhibitory concentration in less than one week. Once the cells have occupied the regions with less drug concentration, they tend to migrate toward the regions with higher drug concentration in a collective behavior. To characterize their resistance, we collect them from this microfluidic system, for further analysis of the dose response. We find that the IC50 (drug concentration that inhibits 50% of controlled population) of the cells, undergone a drug gradient, increase 16-fold of the wildtype cells. We further discover that these resistant cells express more Multidrug Resistance (mdr) protein, which pumps out the drugs and causes drug resistance, than the wildtype. Our current works on RNA-sequencing analysis may discover other biomolecular mechanisms that may confer the drug resistance.

  16. Comparative study on density gradients and swim-up preparation techniques utilizing neat and cryopreserved spermatozoa

    Institute of Scientific and Technical Information of China (English)

    Shyam S.R. Allamaneni; Ashok Agarwal; Sreedhar Rama; Pavithra Ranganathan; Rakesh K. Sharma

    2005-01-01

    Aim: To 1) compare post-wash and post-thaw parameters of sperm processed with PureSperm density gradient technique and swim-up method; and 2) test the efficacy of two commonly available density gradient media PureSperm and Isolate. Methods: This prospective study used semen specimens from 22 patients. Specimens from nine patients were processed by both PureSperm density gradient and swim-up method. These specimens were then cryopreserved.Thirteen specimens were processed by both PureSperm (40 % and 80 %) and Isolate (50 % and 90 %) double density gradient techniques. The two fractions processed by both PureSperm and swim-up were analyzed for post-wash sperm characteristics. Post-thaw analysis was done after 24 hours. Sperm fractions obtained after processing with PureSperm and Isolate were compared for post-wash sperm characteristics and ROS levels. Results: Specimens prepared with PureSperm had significantly higher median total motile sperm counts (TMSC) (32.2 × 106 vs.17.6 × 106), recovery rates (69.2 % vs. 50.0 %), and longevity at 4 hours (83.0 % vs. 55.0 %) compared to specimen prepared by swim-up. Post-thaw specimens also had a higher recovery and longevity at 4 hours with PureSperm as compared to the swim-up. Semen specimens processed by PureSperm had significantly higher total sperm count,TMSC, and percentage recovery rates (30.0 % vs. 19.7 %) than Isolate. Conclusion: Semen quality is better preserved in fresh and cryopreserved semen prepared with PureSperm density gradient compared to swim-up. A significant enrichment of sperm is observed with PureSperm compared to Isolate. Higher recovery rates of mature motile sperm obtained after PureSperm sperm preparation may be beneficial for successful ART.

  17. Preparation of polyacrylamide gel-filled capillaries with step gradients and low UV-detection background

    Institute of Scientific and Technical Information of China (English)

    陈义

    1997-01-01

    Polyacrylamide- filled capillaries with step gradients were designed and prepared with a newly established method,which is also suitable for producing other sorts of capillaries.The resulting capillaries allow the use of any UV light to approach the most sensitive detection and have the features of fast running speed and high separation efficiency In addition,the capillaries can he used continuously for more than two weeks.

  18. Miniaturized Antimicrobial Susceptibility Test by Combining Concentration Gradient Generation and Rapid Cell Culturing

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    Samuel C. Kim

    2015-10-01

    Full Text Available Effective treatment of bacterial infection relies on timely diagnosis and proper prescription of antibiotic drugs. The antimicrobial susceptibility test (AST is one of the most crucial experimental procedures, providing the baseline information for choosing effective antibiotic agents and their dosages. Conventional methods, however, require long incubation times or significant instrumentation costs to obtain test results. We propose a lab-on-a-chip approach to perform AST in a simple, economic, and rapid manner. Our assay platform miniaturizes the standard broth microdilution method on a microfluidic device (20 × 20 mm that generates an antibiotic concentration gradient and delivers antibiotic-containing culture media to eight 30-nL chambers for cell culture. When tested with 20 μL samples of a model bacterial strain (E. coli ATCC 25922 treated with ampicillin or streptomycin, our method allows for the determination of minimum inhibitory concentrations consistent with the microdilution test in three hours, which is almost a factor of ten more rapid than the standard method.

  19. Preparation of Avocado Mitochondria Using Self-Generated Percoll Density Gradients and Changes in Buoyant Density during Ripening.

    Science.gov (United States)

    Moreau, F; Romani, R

    1982-11-01

    Mitochondria from avocado (Persea americana Mill, var. Fuerte and Hass) can be rapidly prepared at every stage of ripening using differential centrifugation and self-generated Percoll gradients. The procedure results in improved oxidative and phosphorylative properties, especially for mitochondria isolated from preclimacteric fruits.A gradual change in the buoyant density of avocado mitochondria takes place during ripening. Climacteric and postclimacteric avocado mitochondria have the same buoyant density as other plant mitochondria (potato, cauliflower), whereas mitochondria from preclimacteric fruit have a lower density. The transition in buoyant density occurs during the climacteric rise, and two populations of intact mitochondria (p = 1.060 and p = 1.075) can be separated at this stage. Evidence indicates that the difference in mitochondrial buoyant density between preclimacteric and postclimacteric mitochondria is likely due to interactions with soluble cytosolic components.

  20. Preparation and evaluation of a biomimetic scaffold with porosity gradients in vitro

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    Qianbin Wang

    2012-03-01

    Full Text Available A novel biodegradable scaffold based on mimetic a natural bone tissue morphology with a porosity gradient structure was prepared in this paper. The result of surface morphology indicated that a graded porous structure was formed in the fabricated scaffold, where the dense layer (0% was connected with the most porous layer (60% by a middling porous layer (30%. To evaluate the degradability, graded porous scaffolds compared with homogeneous scaffolds were placed into a Tris-HCl buffer solution (pH = 7.4 for 28 days. It was found that both scaffolds presented the same degradation trend, and the graded porous structure did not change the original degradability of the scaffold. Moreover, the compressive strength of the graded porous scaffold was better than that of conventional homogeneous scaffold with the increase of degradation time, and the graded porous structure can enhanced the mechanical property of the scaffold. These findings suggest that this biodegradable and porosity-graded scaffold may be a new promising scaffold for loaded bone implant.Um novo esqueleto mimetizando a morfologia de tecido ósseo e com uma estrutura de porosidade gradiente foi preparado e é descrito neste artigo. O resultado da avaliação da morfologia da superfície indicou que uma estrutura porosa gradiente se formou no esqueleto fabricado no qual uma camada densa (0% foi conectada com a camada mais porosa (60% por uma camada porosa média (30%. Para avaliar a degradabilidade, esqueletos de porosidade gradiente e esqueletos homogêneos foram colocados em uma solução tampão Tris-HCL (pH = 7,4 durante 28 dias. Observou-se que ambos os esqueletos apresentaram a mesma tendência de degradação e a estrutura de porosidade gradiente não modificou a degradabilidade original do esqueleto. Além disso, a força compressiva do esqueleto de porosidade gradiente foi melhor do que aquela do esqueleto homogêneo convencional, com aumento do tempo de degradação, e que a

  1. Preparation and characterization of chemical gradient surfaces and their application for the study of cellular interaction phenomena

    NARCIS (Netherlands)

    Ruardy, TG; Schakenraad, JM; vanderMei, HC; Busscher, HJ

    1997-01-01

    Chemical gradient surfaces are surfaces with a gradually changing chemistry along their length which is responsible for a position bound variation in physical properties, most notably, the wettability. In this review, methods to prepare (palladium deposition, diffusion technique, density gradient me

  2. Preparation and characterization of chemical gradient surfaces and their application for the study of cellular interaction phenomena

    NARCIS (Netherlands)

    Ruardy, TG; Schakenraad, JM; vanderMei, HC; Busscher, HJ

    1997-01-01

    Chemical gradient surfaces are surfaces with a gradually changing chemistry along their length which is responsible for a position bound variation in physical properties, most notably, the wettability. In this review, methods to prepare (palladium deposition, diffusion technique, density gradient me

  3. Microstructure and properties of SiC gradiently coated Cf/C composites prepared by a RCLD method

    Institute of Scientific and Technical Information of China (English)

    Jun-hua Chen; Cuang-li Chen; Hao-ran Geng; Yan Wang

    2009-01-01

    The SiC gradiently coated carbon fiber/carbon (Cf/C) composites were prepared by a two-step rapid chemical liquid depo-sition (RCLD) method. The microstructure and properties of the composites were investigated using X-ray diffraction, scanning elec-tron microscopy together with energy dispersive X-ray analysis, bending tests, and oxidation tests. The experimental results show that the surface layer of the composites is composed of SiC, pyrocarbon, and carbon fibers. Their inner area consists of pyrocarbon and carbon fibers. The SiC content gradiently decreases with increasing distance from the outer surface to the center of the compos-ites. Furthermore, the thickness of the SiC layer increases with increasing tetraethylorthosilicate content and deposition time. SiC coatings have no significant influence on the bending strength of the composites. However, the oxidation resistance of the compos-ites increases with increasing thickness of the SiC layer.

  4. Rapid 3-D forward modeling of gravity and gravity gradient tensor fields

    Science.gov (United States)

    Longwei, C.; Dai, S.; Zhang, Q.

    2014-12-01

    Three-dimensional inversion are the key process in gravity exploration. In the commonly used scheme of inversion, the subsurface of the earth is usually divided into many small prism blocks (or grids) with variable density values. A key task in gravity inversion is to calculate the composite fields (gravity and gravity gradient tensor) generated by all these grids, this is known as forward modeling. In general forward modeling is memory-demanding and time-consuming. One scheme to rapidly calculate the fields is to implement it in Fourier domain and use fast Fourier transform algorithm. The advantage of the Fourier domain method is, obviously, much faster. However, the intrinsic edge effect of the Fourier domain method degrades the precision of the calculated fields. We have developed an innovative scheme to directly calculate the fields in spatial domain. There are two key points in this scheme. One key point is spatial discretization. Spatial convolution formula is discretized using an approach similar to normal difference method. A key idea during discretization is to use the analytical formula of a cubic prism, and this makes the resultant discrete formula have clear physical meaning: it embodies the superposition principle of the fields and is the exact formula to calculate the fields generated by all grids. The discretization only requires the grids have the same dimension in horizontal directions, and grids in different layers may have different dimension in vertical direction, and this offers more flexibility for inversion. Another key point is discrete convolution calculation. We invoke a high efficient two-dimensional discrete convolution algorithm, and it guarantees both time-saving and memory-saving. Its memory cost has the same order as the number of grids. Numerical test result shows that for a model with a dimension of 1000x1000x201 grids, it takes about 300s to calculate the fields on 1000x1000 field points in a personal computer with 3.4-GHz CPU

  5. Autoclave method for rapid preparation of bacterial PCR-template DNA.

    Science.gov (United States)

    Simmon, Keith E; Steadman, Dewey D; Durkin, Sarah; Baldwin, Amy; Jeffrey, Wade H; Sheridan, Peter; Horton, Rene; Shields, Malcolm S

    2004-02-01

    An autoclave method for preparing bacterial DNA for PCR template is presented, it eliminates the use of detergents, organic solvents, and mechanical cellular disruption approaches, thereby significantly reducing processing time and costs while increasing reproducibility. Bacteria are lysed by rapid heating and depressurization in an autoclave. The lysate, cleared by microcentrifugation, was either used directly in the PCR reaction, or concentrated by ultrafiltration. This approach was compared with seven established methods of DNA template preparation from four bacterial sources which included boiling Triton X-100 and SDS, bead beating, lysozyme/proteinase K, and CTAB lysis method components. Bacteria examined were Enterococcus and Escherichia coli, a natural marine bacterial community and an Antarctic cyanobacterial-mat. DNAs were tested for their suitability as PCR templates by repetitive element random amplified polymorphic DNA (RAPD) and denaturing gradient gel electrophoresis (DGGE) analysis. The autoclave method produced PCR amplifiable template comparable or superior to the other methods, with greater reproducibility, much shorter processing time, and at a significantly lower cost.

  6. Temperature Gradient Approach for Rapidly Assessing Sensor Binding Kinetics and Thermodynamics.

    Science.gov (United States)

    Wagner, Caleb E; Macedo, Lucyano J A; Opdahl, Aric

    2015-08-01

    We report a highly resolved approach for quantitatively measuring the temperature dependence of molecular binding in a sensor format. The method is based on surface plasmon resonance (SPR) imaging measurements made across a spatial temperature gradient. Simultaneous recording of sensor response over the range of temperatures spanned by the gradient avoids many of the complications that arise in the analysis of SPR measurements where temperature is varied. In addition to simplifying quantitative analysis of binding interactions, the method allows the temperature dependence of binding to be monitored as a function of time, and provides a straightforward route for calibrating how temperature varies across the gradient. Using DNA hybridization as an example, we show how the gradient approach can be used to measure the temperature dependence of binding kinetics and thermodynamics (e.g., melt/denaturation profile) in a single experiment.

  7. SU-E-T-78: A Study of Dose Falloff Gradient in RapidArc Planning of Lung SBRT

    Energy Technology Data Exchange (ETDEWEB)

    Desai, D; Srinivasan, S; Elasmar, H [Memorial Health Care System, Chattanooga, TN (United States); Johnson, E [Univ Kentucky Medical Ctr, Lexington, KY (United States)

    2015-06-15

    Purpose: Rapid dose falloff beyond PTV is an important criterion for normal tissue sparing in SBRT. RTOG protocols use D2cm and R50% for plan quality evaluation. This study is aimed at analyzing the dose falloff gradient beyond the PTV extending into normal tissue structures and to ascertain the impact of PTV geometry and location on the dose falloff gradient in RapidArc planning of lung SBRT Methods: In this retrospective study, we analyzed 39 clinical RapidArc lung SBRT treatment plans that met RTOG-0915 criteria. Planning was done on Eclipse 8.9 for delivery on either Novalis NTx or TrueBeam STx equipped with HD MLCs. PTV volumes ranged between 5.3 and 113 cc (2.2 to 6 cm sphere equivalent diameter respectively) and their geographic locations were distributed in both lungs. 6X, 6X-FFF, 10X, and 10X-FFF energies were used for planning. All of these SBRT plans were planned using either 2 or 3 full or hemi arcs, with moderate couch kicks. Dose falloff gradients were obtained by generating 7 concentric 5 mm rings beyond PTV surface. Mean dose in each ring is used to evaluate percentage dose falloff gradient as a function of distance from the PTV surface. Results: The mean percentage dose falloff beyond PTV surface in all plans followed an exponential decay and the data was modeled with double exponential decay fit. Photon energy selection in the plan had a minimal impact on the mean percentage dose fall off beyond PTV surface. Conclusion: Dose falloff beyond PTV surface as a function of distance can be ascertained by the use of the double exponential decay fit coefficients in RapidArc planning of lung SBRT. This will help also in plan quality evaluation in addition to D2cm and R50% defined by RTOG.

  8. Rapid separation of Arabidopsis male gametophyte developmental stages using a Percoll gradient.

    Science.gov (United States)

    Dupl'áková, Nikoleta; Dobrev, Petre I; Reňák, David; Honys, David

    2016-10-01

    Research investigating the dynamics of male gametophyte (MG) development has proven to be challenging for the plant science community. Here we describe our protocol for separating Arabidopsis MG developmental stages, which is based on the centrifugation of pollen through a discontinuous Percoll concentration gradient. This Percoll gradient can be formed using a pipette, and it does not require a gradient maker. The purity of the isolated developing spores is as high as 70%, and in most separations it is well above 80%. Using this protocol, we can separate four different stages of pollen development-uninucleate microspore (UNM), bicellular pollen (BCP), tricellular immature pollen (TCP) and mature pollen grain (MPG). The duration of the separation procedure, excluding the cutting of flower inflorescences, is 6 h. This is reduced to 4 h when using a vacuum cleaning method to remove the MPGs before the Percoll density separation.

  9. A Magnetic Resonance Measurement Technique for Rapidly Switched Gradient Magnetic Fields in a Magnetic Resonance Tomograph

    Directory of Open Access Journals (Sweden)

    K. Bartušek

    2003-01-01

    Full Text Available This paper describes a method for measuring of the gradient magnetic field in Nuclear Magnetic Resonance (NMR tomography, which is one of the modern medical diagnostic methods. A very important prerequisite for high quality imaging is a gradient magnetic field in the instrument with exactly defined properties. Nuclear magnetic resonance enables us to measure the pulse gradient magnetic field characteristics with high accuracy. These interesting precise methods were designed, realised, and tested at the Institute of Scientific Instruments (ISI of the Academy of Sciences of the Czech Republic. The first of them was the Instantaneous Frequency (IF method, which was developed into the Instantaneous Frequency of Spin Echo (IFSE and the Instantaneous Frequency of Spin Echo Series (IFSES methods. The above named methods are described in this paper and their a comparison is also presented.

  10. Inducing magnetic anisotropy and optimized microstructure in rapidly solidified Nd-Fe-B based magnets by thermal gradient, magnetic field and hot deformation

    Science.gov (United States)

    Zhao, L. Z.; Li, W.; Wu, X. H.; Hussain, M.; Liu, Z. W.; Zhang, G. Q.; Greneche, J. M.

    2016-10-01

    Direct preparation of Nd-Fe-B alloys by rapid solidification of copper mold casting is a very simple and low cost process for mini-magnets, but these magnets are generally magnetically isotropic. In this work, high coercivity Nd24Co20Fe41B11Al4 rods were produced by injection casting. To induce magnetic anisotropy, temperature gradient, assisted magnetic field, and hot deformation (HD) procedures were employed. As-cast samples showed non-uniform microstructure due to the melt convection. The thermal gradient during solidification led to the formation of radially distributed acicular hard magnetic grains, which gives the magnetic anisotropy. The growth of the oriented grains was confirmed by phase field simulation. A magnetic field up to 1 T applied along the casting direction could not induce significant magnetic anisotropy, but it improved the magnetic properties by reducing the non-uniformity and forming a uniform microstructure. The annealed alloys exhibited high intrinsic coercivity but disappeared anisotropy. HD was demonstrated to be a good approach for inducing magnetic anisotropy and enhanced coercivity by deforming and refining the grains. This work provides an alternative approach for preparing fully dense Nd-rich anisotropic bulk Nd-Fe-B magnets.

  11. Template preparation for rapid PCR in Colletotrichum lindemuthianum

    Directory of Open Access Journals (Sweden)

    Roca M. Gabriela

    2003-01-01

    Full Text Available Isolation of DNA for PCR is time-consuming and involves many reagents. The aim of this work was to optimise a rapid and easy PCR methodology without previous DNA isolation. Different strains of the phytopathogenic fungus Colletotrichum lindemuthianum were used. Protoplasts were generated using lytic enzymes under high incubation temperatures using different methodologies to obtain the template. A rapid (10 minute methodology was successful for smaller amplicons (<750 bp.

  12. Rapid porcelain veneers: smile design, preparation, and cementation.

    Science.gov (United States)

    Javaheri, D S

    2001-11-01

    A technique for replacing existing porcelain veneers has been presented. Technique for smile design, tooth preparation, and cementation were described. The objective was to meet the patient's aesthetic expectations while also meeting functional requirements.

  13. Spatial gradients in Clovis-age radiocarbon dates across North America suggest rapid colonization from the north.

    Science.gov (United States)

    Hamilton, Marcus J; Buchanan, Briggs

    2007-10-02

    A key issue in the debate over the initial colonization of North America is whether there are spatial gradients in the distribution of the Clovis-age occupations across the continent. Such gradients would help indicate the timing, speed, and direction of the colonization process. In their recent reanalysis of Clovis-age radiocarbon dates, Waters and Stafford [Waters MR, Stafford TW, Jr (2007) Science 315:1122-1126] report that they find no spatial patterning. Furthermore, they suggest that the brevity of the Clovis time period indicates that the Clovis culture represents the diffusion of a technology across a preexisting pre-Clovis population rather than a population expansion. In this article, we focus on two questions. First, we ask whether there is spatial patterning to the timing of Clovis-age occupations and, second, whether the observed speed of colonization is consistent with demic processes. With time-delayed wave-of-advance models, we use the radiocarbon record to test several alternative colonization hypotheses. We find clear spatial gradients in the distribution of these dates across North America, which indicate a rapid wave of advance originating from the north. We show that the high velocity of this wave can be accounted for by a combination of demographic processes, habitat preferences, and mobility biases across complex landscapes. Our results suggest that the Clovis-age archaeological record represents a rapid demic colonization event originating from the north.

  14. Rapid Preparation of Monolithic Columns for Capillary Electrochromatography Separation

    Institute of Scientific and Technical Information of China (English)

    Wen Jun GONG; Yi Jun ZHANG; Yu Ping ZHANG; Seong Ho CHOI

    2006-01-01

    Fritless packed silica gel columns were prepared using sol-gel technology. The part of a75 μm i.d. capillary was filled with a mixture of methacryloxypropyltrimethoxysilane, toluene and hydrochloric acid. Four different photoinitiators such as benzoin methyl ether, Irgacure 819,Irgacure 1700 and irgacure 1800 were added in the presence or absence of sodium dodecyl sulfate during the polymerization process. The above eight solutions were irradiated at 365 nm about5-10 min to prepare the porous monolithic sol-gel columns by a one-step process.

  15. Rapid quantitative method for the detection of phenylalanine and tyrosine in human plasma using pillar array columns and gradient elution.

    Science.gov (United States)

    Song, Yanting; Takatsuki, Katsuya; Sekiguchi, Tetsushi; Funatsu, Takashi; Shoji, Shuichi; Tsunoda, Makoto

    2016-07-01

    This study reports a fast and quantitative determination method for phenylalanine (Phe) and tyrosine (Tyr) in human plasma using on-chip pressure-driven liquid chromatography. A pillar array column with low-dispersion turns and a gradient elution system was used. The separation of fluorescent derivatives of Phe, Tyr, and other hydrophobic amino acids was successfully performed within 140 s. Under the optimized conditions, Phe and Tyr in human plasma were quantified. The developed method is promising for rapid diagnosis in the clinical field.

  16. Simple, rapid method for the preparation of isotopically labeled formaldehyde

    Energy Technology Data Exchange (ETDEWEB)

    Hooker, Jacob Matthew [Port Jefferson, NY; Schonberger, Matthias [Mains, DE; Schieferstein, Hanno [Aabergen, DE; Fowler, Joanna S [Bellport, NY

    2011-10-04

    Isotopically labeled formaldehyde (*C.sup..sctn.H.sub.2O) is prepared from labeled methyl iodide (*C.sup..sctn.H.sub.3I) by reaction with an oxygen nucleophile having a pendant leaving group. The mild and efficient reaction conditions result in good yields of *C.sup..sctn.H.sub.2O with little or no *C isotopic dilution. The simple, efficient production of .sup.11CH.sub.2O is described. The use of the .sup.11CH.sub.2O for the formation of positron emission tomography tracer compounds is described. The reaction can be incorporated into automated equipment available to radiochemistry laboratories. The isotopically labeled formaldehyde can be used in a variety of reactions to provide radiotracer compounds for imaging studies as well as for scintillation counting and autoradiography.

  17. Preparation and Properties of Plasma Spraying Cu-Al2O3 Gradient Coatings

    Institute of Scientific and Technical Information of China (English)

    Ali LEI; Nan DONG; Lajun FENG

    2007-01-01

    In order to overcome the limitations of low adhesion strength and poor thermal-shock resistance of pure ceramic coatings, Cu-Al2O3 gradient coatings were fabricated by plasma spraying. The microstructure and distribution of Cu-Al2O3 gradient coatings were analyzed. The adhesion strength, thermal-shock resistance and porosity of the coatings were tested. The results show that the composition of the gradient coatings has a gradient distribution along the thickness of coatings. As copper has a relatively low melting point and the molten copper has good wettability on the surface of Al2O3, it can be melted sufficiently and could fill the interstices and pores among the spraying particles effectively, thus improves the adhesion strength, thermal shock resistance and reduces the porosity. The adhesion strength of the gradient coating is 15.2 MPa which is two times of that of the double-layer structure coating.

  18. A facile strategy for rapid preparation of graphene spongy balls

    Science.gov (United States)

    Wan, Shu; Bi, Hengchang; Xie, Xiao; Su, Shi; Du, Kai; Jia, Haiyang; Xu, Tao; He, Longbing; Yin, Kuibo; Sun, Litao

    2016-09-01

    Porous three dimensional (3D) graphene macrostructures have demonstrated the potential in versatile applications in recent years, including energy storage, sensors, and environment protection, etc. However, great research attention has been focused on the optimization of the structure and properties of graphene-based materials. Comparatively, there are less reports on how to shape 3D graphene macrostructures rapidly and effortlessly, which is critical for mass production in industry. Here, we introduce a facile and efficient method, low temperature frying to form graphene-based spongy balls in liquid nitrogen with a yield of ~400 balls min‑1. Moreover, the fabrication process can be easily accelerated by using multi pipettes working at the same time. The graphene spongy balls show energy storage with a specific capacitance of 124 F g‑1 and oil adsorbing with a capacity of 105.4 times its own weight. This strategy can be a feasible approach to overcome the low efficiency in production and speed up the development of porous 3D graphene-based macrostructures in industrial applications.

  19. Combination of direct swim-up technique and discontinuous Percoll gradient centrifugation for sperm preparation of oligoasthenozoospermic samples.

    Science.gov (United States)

    Chen, S U; Ho, H N; Chen, H F; Chao, K H; Wu, M Y; Chen, C D; Huang, S C; Lee, T Y; Yang, Y S

    1996-01-01

    Sperm recovery for assisted reproduction in oligoasthenozoospermic patients is not satisfying either by the swim-up technique or by Percoll gradient centrifugation, and no single technique is constantly preferred. The design of this study was to evaluate the effects of combining the two methods on improving the efficacy of sperm preparation in these poor samples. For each semen sample, 1 mL was treated with a combination method, which used direct swim-up technique to recover motile sperm swimming to the supernatant, and then the residual semen was subjected to two-layer discontinuous Percoll gradient procedure for further recovery of motile sperm. Another 1 mL was prepared with two-layer discontinuous Percoll gradient centrifugation alone for comparison. Parameters measured included sperm concentration, number of progressively motile sperm, percentage of progressive motility, percentage of motile sperm recovery, amount of debris, percentage of normal forms according to Kruger's strict criteria, and motion characteristics of sperm using computer-aided motility analysis. The results of 30 oligoasthenozoospermic samples demonstrated that the combination method achieved a significantly greater recovery of motile sperm than the two-layer discontinuous Percoll gradient centrifugation did (43.2 +/- 19.7% vs. 32.2 +/- 14.3%, p method than in those of Percoll gradient centrifugation alone, but the difference was not significant (63.7 +/- 21.8% vs. 58.7 +/- 20.1%). The debris of semen was removed equally well by both methods. The percentage of normal forms as well as motion characteristics, including curvilinear velocity, straight-line velocity, mean amplitude of lateral head displacement, and linearity, were similar in the samples treated by these two procedures. The combination of the direct swim-up technique and discontinuous Percoll gradient centrifugation combines the advantages of each procedure and results in greater recovery of motile sperm in oligoasthenozoospermic

  20. Preparation and properties of gradient Al2O3-ZrO2 ceramic foam by centrifugal slip casting method

    Directory of Open Access Journals (Sweden)

    Li Qiang

    2012-11-01

    Full Text Available The aim of the present research is to provide a novel technique for preparing gradient Al2O3-ZrO2 ceramic foams. This technique used epispastic polystyrene spheres to array templates and centrifugal slip casting to obtain cell struts with gradient distribution of Al2O3 and ZrO2 particles and high packing density. Aqueous Al2O3-20vol.% ZrO2 slurries with 20vol.% solid contents were prepared and the dispersion and rheological characteristics of the slurries were investigated. The settling velocity and mass segregation of Al2O3 and ZrO2 particles at different centrifugal accelerations were calculated and studied. The drying behavior, macrostructure, microstructure, compressive property and resistance to thermal shock of the sintered products were also investigated. The results show that the difference of settling velocity of Al2O3 and ZrO2 particles increases and mass segregation becomes acute with an increase in centrifugal acceleration. The cell struts prepared at a centrifugal acceleration of 1,690 g have high sintered density (99.0% TD and continuous gradient distribution of Al2O3 and ZrO2 particles. When sintered at 1,550 oC for 2 h, the cell size of gradient Al2O3-ZrO2 foam is approximately uniform, about 1.1 mm. With the porosity of gradient Al2O3-ZrO2 ceramic foams increasing from 75.3% to 83.0%, the compressive strength decreases from 4.4 to 2.4 MPa, and the ceramic foams can resist 8-11 repeated thermal shock from 1,100 oC to room temperature.

  1. Preparation of polyacrylamide based monolith with immobilized pH gradient and its application for protein analysis

    Institute of Scientific and Technical Information of China (English)

    ZHU GuiJie; ZHANG WeiBing; ZHANG LiHua; LIANG Zhen; ZHANG YuKui

    2007-01-01

    Monolithic materials were prepared in capillaries by in situ polymerization of acrylamide, glycidyl methacrylate and N,N'-memylenebisacrylamid in the presence of trinary porogens, including 1,4-butanediol, dodecanol and dimethyl sulphoxide. With Ampholine immobilized on the monolith by chemical bonding according to their pIs, the monolithic immobilized pH gradient (M-IPG) was prepared, and applied to the separation of four standard proteins. Compared with polyacrylate based M-IPG, the hydrophilicity of the new material was improved. It could not only avoid the adsorption of proteins, but also make the synthesized procedure simple, which showed great potential in the analysis of proteins.

  2. Preparation of polyacrylamide based monolith with immobilized pH gradient and its application for protein analysis

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Monolithic materials were prepared in capillaries by in situ polymerization of acrylamide, glycidyl methacrylate and N,N′-memylenebisacrylamid in the presence of trinary porogens, including 1,4-butanediol, dodecanol and dimethyl sulphoxide. With Ampholine immobilized on the monolith by chemical bonding according to their pIs, the monolithic immobilized pH gradient (M-IPG) was prepared, and applied to the separation of four standard proteins. Compared with polyacrylate based M-IPG, the hydrophilicity of the new material was improved. It could not only avoid the adsorption of proteins, but also make the synthesized procedure simple, which showed great potential in the analysis of proteins.

  3. Rapid processing of carbon-carbon composites by forced flow-thermal gradient chemical vapor infiltration (FCVI)

    Energy Technology Data Exchange (ETDEWEB)

    Vaidyaraman, S.; Lackey, W.J.; Agrawal, P.K.; Freeman, G.B.; Langman, M.D. [Georgia Inst. of Tech., Atlanta, GA (United States)

    1995-10-01

    Carbon fiber-carbon matrix composites were fabricated using the forced flow-thermal gradient chemical vapor infiltration (FCVI) process. Preforms were prepared by stacking 40 layers of plain weave carbon cloth in a graphite holder. The preforms were infiltrated using propylene, propane, and methane. The present work showed that the FCVI process is well suited for fabricating carbon-carbon composites; without optimization of the process, the authors have achieved uniform and thorough densification. Composites with porosities as low as 7% were fabricated in 8--12 h. The highest deposition rate obtained in the present study was {approximately}3 {micro}m/h which is more than an order of magnitude faster than the typical value of 0.1--0.25 {micro}m/h for the isothermal process. It was also found that the use of propylene and propane as reagents resulted in faster infiltration compared to methane.

  4. An experimental study of pyroxene crystallization during rapid cooling in a thermal gradient; applications to komatiites and chondrites

    Directory of Open Access Journals (Sweden)

    S. Bouquain

    2013-03-01

    Full Text Available To investigate the crystallization of pyroxene in spinifex-textured komatiites and in chondrites we undertook a series of experiments in which compositions in the CMAS system were cooling rapidly in a thermal gradient. Cooling rates were generally between 5 to 10 °C h−1 but some runs were made at 100–200 °C h−1; thermal gradients were between 10 and 20 °C cm−1. These conditions reproduced those at various levels in the crust of komatiitic lava flow. The starting composition was chosen to have pigeonite on the liquidus and a majority of the experiments crystallized zoned pigeonite-diopside crystals like those in komatiite lavas. A~conspicuous aspect of the experimental results was their lack of reproduceability. Some experiments crystallized forsterite whereas others that were run under similar conditions crystallized two pyroxenes and no forsterite; some experiments were totally glassy but others totally crystallized to pyroxene. The degree of supercooling at the onset of pyroxene crystallization was variable, from less than 25 °C to more than 110 °C. We attribute these results to the difficulty of nucleation of pyroxene. In some cases forsterite crystallized metastably and modified the liquid composition to inhibit pyroxene crystallization; in others no nucleation took place until a large degree of supercooling was achieved, then pyroxene crystallized rapidly. Pigeonite crystallized under a wide range of conditions, at cooling rates from 3 to 100 °C h−1. The notion that this mineral only forms at low cooling rates is not correct.

  5. Rapid Directional Solidification with Ultra-High Temperature Gradient and Cellular Spacing Selection of Cu-Mn Alloy

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The detailed laser surface remelting experiments of Cu-31.4 wt pct Mn and Cu-26.6 wt pct Mn alloys on a 5 kW CO2laser were carried out to study the effects of processing parameters (scanning velocity, output power of laser) on the growthdirection of microstructure in the molten pool and cellular spacing selection under the condition of ultra-high temperaturegradient and rapid directional solidification. The experimental results show that the growth direction of microstructure isstrongly affected by laser processing parameters. The ultra-high temperature gradient directional solidification can be realizedon the surface of samples during laser surface remelting by controlling laser processing parameters, the temperature gradientand growth velocity can reach 106 K/m and 24.1 mm/s, respectively, and the solidification microstructure in the center ofthe molten pool grows along the laser beam scanning direction. There exists a distribution range of cellular spacings underthe laser rapid solidification conditions, and the average spacing decreases with increasing of growth rate. The maximum,λ minimum, λmin, and average primary spacing,λ, as functions of growth rate, Vb, can be given by, λ =12.54V b-0.61,λmin=4.47 Vb-0.52, λ=9.09Vb-0.62, respectively. The experimental results are compared with the current Hunt-Lu model forrapid cellular/dendritic growth, and a good agreement is found.

  6. Platelet adhesion and activation on a shielded plasma gradient prepared on polyethylene

    NARCIS (Netherlands)

    Spijker, HT; Busscher, HJ; van Kooten, TG; van Oeveren, W; Bos, R.R.M.

    2002-01-01

    Contact of blood with foreign materials evokes thrombogenic effects to an extent determined partly by the wettability of the biomaterials Surface. Tools to study blood response towards a variation in materials wettability with minimal variation in chemistry are "gradient surfaces". However, most gra

  7. BREATHING FIRE: HOW STELLAR FEEDBACK DRIVES RADIAL MIGRATION, RAPID SIZE FLUCTUATIONS, AND POPULATION GRADIENTS IN LOW-MASS GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    El-Badry, Kareem; Geha, Marla [Department of Astronomy, Yale University, New Haven, CT (United States); Wetzel, Andrew; Hopkins, Philip F. [TAPIR, California Institute of Technology, Pasadena, CA USA (United States); Kereš, Dusan; Chan, T. K. [Department of Physics, Center for Astrophysics and Space Sciences, University of California at San Diego, La Jolla (United States); Faucher-Giguère, Claude-André, E-mail: kareem.el-badry@yale.edu [Department of Physics and Astronomy and CIERA, Northwestern University, Evanston, IL (United States)

    2016-04-01

    We examine the effects of stellar feedback and bursty star formation on low-mass galaxies (M{sub star} = 2 × 10{sup 6} − 5 × 10{sup 10} M{sub ⊙}) using the Feedback in Realistic Environments (FIRE) simulations. While previous studies emphasized the impact of feedback on dark matter profiles, we investigate the impact on the stellar component: kinematics, radial migration, size evolution, and population gradients. Feedback-driven outflows/inflows drive significant radial stellar migration over both short and long timescales via two processes: (1) outflowing/infalling gas can remain star-forming, producing young stars that migrate ∼1 kpc within their first 100 Myr, and (2) gas outflows/inflows drive strong fluctuations in the global potential, transferring energy to all stars. These processes produce several dramatic effects. First, galaxies’ effective radii can fluctuate by factors of >2 over ∼200 Myr, and these rapid size fluctuations can account for much of the observed scatter in the radius at fixed M{sub star}. Second, the cumulative effects of many outflow/infall episodes steadily heat stellar orbits, causing old stars to migrate outward most strongly. This age-dependent radial migration mixes—and even inverts—intrinsic age and metallicity gradients. Thus, the galactic-archaeology approach of calculating radial star formation histories from stellar populations at z = 0 can be severely biased. These effects are strongest at M{sub star} ≈ 10{sup 7–9.6} M{sub ⊙}, the same regime where feedback most efficiently cores galaxies. Thus, detailed measurements of stellar kinematics in low-mass galaxies can strongly constrain feedback models and test baryonic solutions to small-scale problems in ΛCDM.

  8. High throughput analysis at microscale: performance of ionKey/MS with Xevo G2-XS QTof under rapid gradient conditions

    Directory of Open Access Journals (Sweden)

    Yun Wang Alelyunas

    2015-10-01

    Full Text Available In this paper, high throughput analysis with 3 minute, rapid gradient conditions is described using the ionKey/MS™ System with an integrated ACQUITY UPLC® M-Class System and the Xevo® G2-XS QTof Mass Spectrometer. Extensive testing of representative small molecules and a peptide shows that the system is well-tolerated and exhibits excellent reproducibility and linear response. The iKey™ HSS T3 Separation Device used is robust, withstanding ~2200 injections of prepared human plasma with excellent peak shape and system pressure profile. A 99% solvent savings was realized when compared with an analytical system using a 2.1 mm column with flow rate ranging from 0.6 mL/min to 1.5 mL/min. These data, coupled with examples from the literature, illustrate that the ionKey/MS System with Xevo G2-XS QTof can be used as a full service platform for high throughput analysis and high sensitivity analysis to support all phases of drug discovery and development.

  9. Preparation and analysis of chemically gradient functional bioceramic coating formed by pulsed laser deposition.

    Science.gov (United States)

    Rajesh, P; Muraleedharan, C V; Sureshbabu, S; Komath, Manoj; Varma, Harikrishna

    2012-02-01

    Bioactive ceramic coatings based on calcium phosphates yield better functionality in the human body for a variety of metallic implant devices including orthopaedic and dental prostheses. In the present study chemically and hence functionally gradient bioceramic coating was obtained by pulsed laser deposition method. Calcium phosphate bioactive ceramic coatings based on hydroxyapatite (HA) and tricalcium phosphate (TCP) were deposited over titanium substrate to produce gradation in physico-chemical characteristics and in vitro dissolution behaviour. Sintered targets of HA and α-TCP were deposited in a multi target laser deposition system. The obtained deposits were characterized by X-ray diffraction, fourier transform infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray analysis. Inductively coupled plasma spectroscopy was used to estimate the in vitro dissolution behaviour of coatings. The variation in mechanical property of the gradient layer was evaluated through scratch test and micro-indentation hardness. The bioactivity was examined in vitro with respect to the ability of HA layer to form on the surface as a result of contact with simulated body fluid. It could be inferred that chemically gradient functional bioceramic coating can be produced by laser deposition of multiple sintered targets with variable chemical composition.

  10. Breathing FIRE: How Stellar Feedback Drives Radial Migration, Rapid Size Fluctuations, and Population Gradients in Low-Mass Galaxies

    CERN Document Server

    El-Badry, Kareem; Geha, Marla; Hopkins, Philip F; Kereš, Dušan; Chan, T K; Faucher-Giguère, Claude-André

    2015-01-01

    We examine the effects of stellar feedback and bursty star formation on low-mass galaxies ($M_{\\rm star}=2\\times10^6-5\\times10^{10}{\\rm M_{\\odot}}$) using the FIRE (Feedback in Realistic Environments) simulations. While previous studies emphasized the impact of feedback on dark matter profiles, we investigate the impact on the stellar component: kinematics, radial migration, size evolution, and population gradients. Feedback-driven outflows/inflows drive significant radial stellar migration over both short and long timescales via two processes: (1) outflowing/infalling gas can remain star-forming, producing young stars that migrate $\\sim1{\\rm\\,kpc}$ within their first $100 {\\rm\\,Myr}$, and (2) gas outflows/inflows drive strong fluctuations in the global potential, transferring energy to all stars. These processes produce several dramatic effects. First, galaxies' effective radii can fluctuate by factors of $>2$ over $\\sim200 {\\rm\\,Myr}$, and these rapid size fluctuations can account for much of the observed s...

  11. Gradient Structure of Ti-Al-C Ternary Carbide Prepared by Hot-pressing Sintering

    Institute of Scientific and Technical Information of China (English)

    MEI Bingchu; HONG Xiaolin; ZHU Jiaoqun; ZHOU Weibing

    2005-01-01

    X-ray diffraction (XRD) analysis on different polished surfaces normal to the hot pressing direction reveals that the phase compositions of the polished surfaces from the outside to the inside are pure TiC, Ti3AlC2+TiC, pure Ti3AlC2 and Ti2AlC+Ti3AlC2, no matter elemental powder or TiC is used as raw materials. It is found that ternary-layered carbide Ti2AlC samples synthesized at 1500 ℃ by hot-pressing sintering are inhomogeneous and have a gradient structure.Electron probe X-ray micro-analysis (EPMA) indicates that the Al content along the hot pressing axis is parabolic, it is the highest in the center and the lowest at the both ends, while the Ti content is constant along the axis. The experimental result reveals that the evaporation of Al in samples in an open system during hot pressing sintering results in a gradient structure.

  12. Oxidation and Hot Corrosion of Gradient Thermal Barrier Coatings Prepared by EB-PVD

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The performances of gradient thermal barrier coatings (GTBCs) produced by EB-PVD were evaluated by isothermaloxidation and cyclic hot corrosion (HTHC) tests. Compared with conventional two-layered TBCs, the GTBCs exhibitebetter resistance to not only oxidation but also hot-corrosion. A dense Al2O3 layer in the GTBCs effectively prohibitesinward diffusion of O and S and outward diffusion of Al and Cr during the tests. On the other hand, an "inlaid"interface, resulting from oxidation of the Al along the columnar grains of the bond coat, enhances the adherence ofAl2O3 layer. Failure of the GTBC finally occurred by cracking at the interface between the bond coat and Al2O3layer, due to the combined effect of sulfidation of the bond coat and thermal cycling.

  13. Electromembrane extraction as a rapid and selective miniaturized sample preparation technique for biological fluids

    DEFF Research Database (Denmark)

    Gjelstad, Astrid; Pedersen-Bjergaard, Stig; Seip, Knut Fredrik

    2015-01-01

    This special report discusses the sample preparation method electromembrane extraction, which was introduced in 2006 as a rapid and selective miniaturized extraction method. The extraction principle is based on isolation of charged analytes extracted from an aqueous sample, across a thin film....... Technical aspects of electromembrane extraction, important extraction parameters as well as a handful of examples of applications from different biological samples and bioanalytical areas are discussed in the paper....

  14. Preparation and Rapid Analysis of Antibacterial Silver, Copper and Zinc Doped Sol–gel Surfaces

    OpenAIRE

    Jaiswal, Swarna; Duffy, Brendan; McHale, Patrick

    2012-01-01

    The colonisation of clinical and industrial surfaces with microorganisms, including antibiotic-resistant strains, has promoted increased research into the development of effective antibacterial and antifouling coatings. This study describes the preparation of metal nitrate (Ag, Cu, Zn) doped methyltriethoxysilane (MTEOS) coatings and the rapid assessment of their antibacterial activity using polyproylene microtitre plates. Microtitre plate wells were coated with different volumes of liquid so...

  15. Iron Oxide Films Prepared by Rapid Thermal Processing for Solar Energy Conversion

    DEFF Research Database (Denmark)

    Wickman, B.; da Silva Fanta, Alice Bastos; Burrows, Andrew

    2017-01-01

    considerably. Herein, we present hematite thin films fabricated via one-step oxidation of Fe by rapid thermal processing (RTP). In particular, we investigate the effect of oxidation temperature on the PEC properties of hematite. Films prepared at 750 °C show the highest activity towards water oxidation......, potentially also on nanostructured electrodes, where retaining high surface area is crucial to maximize performance....

  16. Extreme Rapid Weight Loss and Rapid Weight Gain Observed in UK Mixed Martial Arts Athletes Preparing for Competition.

    Science.gov (United States)

    Matthews, Joseph John; Nicholas, Ceri

    2016-10-06

    There is a lack of research documenting the weight-making practices of mixed-martial-arts (MMA) competitors. The purpose of the investigation was to quantify the magnitude and identify the methods of rapid weight loss (RWL) and rapid weight gain (RWG) in MMA athletes preparing for competition. Seven athletes (mean ± SD, age 24.6 ± 3.5 yrs, body mass 69.9 ± 5.7 kg, competitive experience 3.1 ± 2.2 yrs) participated in a repeated-measures design. Measures of dietary intake, urinary hydration status, and body mass were recorded in the week preceding competition. Body mass decreased significantly (p<0.0005) from baseline by 5.6 ± 1.4 kg (8 ± 1.8%). During the RWG period (32 ± 1 hours) body mass increased significantly (p<0.001) by 7.4 ± 2.8 kg (11.7 ± 4.7%), exceeding RWL. Mean energy and carbohydrate intake were 3176 ± 482 kcal·day(-1) and 471 ± 124 g·day(-1), respectively. At the official weigh-in 57% of athletes were dehydrated (1033 ± 19 mOsmol·kg(-1)) and the remaining 43% were severely dehydrated (1267 ± 47 mOsmol·kg(-1)). Athletes reported using harmful dehydration-based RWL strategies, including sauna (43%) and training in plastic suits (43%). Results demonstrated RWG greater than RWL, this is a novel finding and may be attributable to the 32 hour duration from weigh-in till competition. The observed magnitude of RWL and strategies used are comparable to those which have previously resulted in fatalities. Rule changes which make RWL impractical should be implemented with immediate effect to ensure the health, safety and wellbeing of competitors.

  17. Preparation of a blood culture pellet for rapid bacterial identification and antibiotic susceptibility testing.

    Science.gov (United States)

    Croxatto, Antony; Prod'hom, Guy; Durussel, Christian; Greub, Gilbert

    2014-10-15

    Bloodstream infections and sepsis are a major cause of morbidity and mortality. The successful outcome of patients suffering from bacteremia depends on a rapid identification of the infectious agent to guide optimal antibiotic treatment. The analysis of Gram stains from positive blood culture can be rapidly conducted and already significantly impact the antibiotic regimen. However, the accurate identification of the infectious agent is still required to establish the optimal targeted treatment. We present here a simple and fast bacterial pellet preparation from a positive blood culture that can be used as a sample for several essential downstream applications such as identification by MALDI-TOF MS, antibiotic susceptibility testing (AST) by disc diffusion assay or automated AST systems and by automated PCR-based diagnostic testing. The performance of these different identification and AST systems applied directly on the blood culture bacterial pellets is very similar to the performance normally obtained from isolated colonies grown on agar plates. Compared to conventional approaches, the rapid acquisition of a bacterial pellet significantly reduces the time to report both identification and AST. Thus, following blood culture positivity, identification by MALDI-TOF can be reported within less than 1 hr whereas results of AST by automated AST systems or disc diffusion assays within 8 to 18 hr, respectively. Similarly, the results of a rapid PCR-based assay can be communicated to the clinicians less than 2 hr following the report of a bacteremia. Together, these results demonstrate that the rapid preparation of a blood culture bacterial pellet has a significant impact on the identification and AST turnaround time and thus on the successful outcome of patients suffering from bloodstream infections.

  18. 超声波焊接制备功能梯度材料%Study on the functional gradient materials prepared by ultrasonic welding

    Institute of Scientific and Technical Information of China (English)

    朱政强; 吴宗辉; 曾纯; 王倩

    2011-01-01

    采用超声波焊接的方法成功制备了功能梯度材料,它具有简便、环保、快速成型的特点.实验以铝合金6061、3003、纯钛、钛合金Ti-6Al-4V和纯镍为材料,利用超声波焊接方法制备Al/Ti/Ni功能梯度材料.通过金相显微分析、显微硬度分析、EDS分析对其焊接界面的微观结构、显微硬度、焊缝原子扩散程度进行测试和表征.结果表明:接头的结合形式常伴有机械嵌合,结合程度趋于金属间的键合,接头总体硬度值增大,在焊缝处达到峰值,界面两侧金属元素能在不到0.2 s的焊接时间下实现界面间的元素相互扩散和渗透,达到梯度材料的设计要求.%This article takes the lead in using ultrasonic welding method successfully to prepare Ti/Al/Ni functional gradient materials with 6061 aluminum alloy,pure titanium,titanium alloy,3003Ti-6Al-4V and pure nickel.This method is simple,environment-friendly and forming rapid,its welding interface microstructure, microhardness,weld atomic diffusion degree was investigated by metallographic micro-structure,micro-hardness and EDS analysis. The results showed that the combining form of the joint is often accompanied by mechanical tabling and combining degree tends to the bonding between metals. The total hardness value of joint increases and the maximum hardness value is the one of weld seams, the metal elements on both sides of the interface can diffuse and penetrate through the interface in less than 0.2 seconds welding time. This gradient materials can achieve the design requirements of gradient materials.

  19. A Simple Device to Rapidly Prepare Whole Mounts of the Mouse Intestine.

    Science.gov (United States)

    Yoneda, Mitsuhiro; Molinolo, Alfredo A; Ward, Jerrold M; Kimura, Shioko; Goodlad, Robert A

    2015-10-27

    Preparing whole mounts of the mouse small intestine and colon for subsequent analysis or quantification can be time consuming and difficult. We describe the use of a simple device to cut and 'roll' mouse intestines to rapidly prepare whole mount preparations of superior and uniform quality to that which can be achieved by hand. The device comprises a base that holds 4 stainless steel rods and a top, which acts a cutting guide. The rods are inserted into the lumen of the small intestine [divided into thirds] and the colon. The rods and samples are then placed over a piece of filter paper or card into the holding slots in the base of the device. The top of the device is then positioned and serves as a cutting guide. The two angled sections in the center of the top piece are used to guide a knife or scalpel and cut the intestines longitudinally on the top of the rods. Once the intestinal sections have been cut, the top is removed and the card, tissue and rods gently removed from the device and placed on the bench. The rods are then gently rolled sideways to flatten and stick the intestinal segments onto the underlying piece of filter paper or card. The final preparation can then be examined or fixed and stored for later analysis. The preparations are invaluable for the study of intestinal changes in normal or genetically modified mouse models. The preparations have been used for the study and quantification of the effects of inflammation (colitis), damage, pre-cancerous lesions (aberrant crypt foci (ACFs) and mucin depleted foci (MDFs)) and polyps or tumors.

  20. Magnetic measurements of superconducting glass-ceramic fine rods in Bi sub 1 Ca sub 1 Sr sub 1 Cu sub 2 Al sub 0. 5 O sub x prepared under a temperature gradient

    Energy Technology Data Exchange (ETDEWEB)

    Higashida, Y.; Yokoyama, H.; Michishita, K.; Kubo, Y.; Yoshida, H. (R D Laboratory, Japan Fine Ceramics Center, Mutuno-cho, Atsuta-ku, Nagoya 456, Japan (JP)); Abe, Y.; Hosono, H. (Department of Materials Science and Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466, Japan)

    1989-10-09

    It is shown that the crystallization of the glass precursor under a temperature gradient is very effective for preparing the superconducting glass ceramics in the Bi-Ca-Sr-Cu-O system. The magnetization measurements show that the specimen prepared under a temperature gradient has a magnetization hysteresis several times larger at 4.2 K than that prepared under no temperature gradient; the coupling between superconducting grains of the former is stronger than that of the latter.

  1. Magnetic measurements of superconducting glass-ceramic fine rods in Bi1Ca1Sr1Cu2Al(0.5)O(x) prepared under a temperature gradient

    Science.gov (United States)

    Higashida, Yutaka; Yokoyama, Hisanori; Michishita, Kazuo; Kubo, Yukio; Yoshida, Hiroshi

    1989-10-01

    It is shown that the crystallization of the glass precursor under a temperature gradient is very effective for preparing the superconducting glass ceramics in the Bi-Ca-Sr-Cu-O system. The magnetization measurements show that the specimen prepared under a temperature gradient has a magnetization hysteresis several times larger at 4.2 K than that prepared under no temperature gradient; the coupling between superconducting grains of the former is stronger than that of the latter.

  2. A Simple and Rapid Method for Preparing a Cell-Free Bacterial Lysate for Protein Synthesis

    Science.gov (United States)

    Kaduri, Maya; Shainsky-Roitman, Janna; Goldfeder, Mor; Ivanir, Eran; Benhar, Itai; Shoham, Yuval; Schroeder, Avi

    2016-01-01

    Cell-free protein synthesis (CFPS) systems are important laboratory tools that are used for various synthetic biology applications. Here, we present a simple and inexpensive laboratory-scale method for preparing a CFPS system from E. coli. The procedure uses basic lab equipment, a minimal set of reagents, and requires less than one hour to process the bacterial cell mass into a functional S30-T7 extract. BL21(DE3) and MRE600 E. coli strains were used to prepare the S30-T7 extract. The CFPS system was used to produce a set of fluorescent and therapeutic proteins of different molecular weights (up to 66 kDa). This system was able to produce 40–150 μg-protein/ml, with variations depending on the plasmid type, expressed protein and E. coli strain. Interestingly, the BL21-based CFPS exhibited stability and increased activity at 40 and 45°C. To the best of our knowledge, this is the most rapid and affordable lab-scale protocol for preparing a cell-free protein synthesis system, with high thermal stability and efficacy in producing therapeutic proteins. PMID:27768741

  3. Preparative SDS-PAGE Electroelution for Rapid Purification of Alkyl Hydroperoxide Reductase from Helicobacter pylori

    Directory of Open Access Journals (Sweden)

    T Mohammadian

    2010-03-01

    Full Text Available "nBackground: Alkyl hydroperoxide reductase (AhpC of Helicobacter pylori is considered as a diagnostic antigen. There­fore, this antigen can be used to detect H. pylori infection by stool immunoassays such as ELISA. The aim of this study was to simplify the AhpC protein purification procedures."nMethods: For whole cell protein extraction, the bacterial cells were ruptured by octly-β-D glucopyranoside. The isolation and purification of  AhpC protein were attempted by various techniques including ammonium sulfate precipitation, dialysis, preparative sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE and electroelution."nResults:A simple method was used for protein purification AhpC protein. One-dimensional preparative gel electrophoresis allows a single and short purification step; the high resolution capacity of this technique leads to a high level of purity of the protein. Moreover, it avoids contamination by other non-specific proteins which often appear during protein purification by column chromatography."nConclusion: The present method is simple, rapid and makes it possible to preparate AhpC from H. pylori

  4. Preparation and in vitro evaluation of ethosomal total alkaloids of Sophora alopecuroides loaded by a transmembrane pH-gradient method.

    Science.gov (United States)

    Zhou, Yan; Wei, Yuhui; Liu, Huanxiang; Zhang, Guoqiang; Wu, Xin'an

    2010-09-01

    A novel transmembrane pH gradient active loading method to prepare alkaloids binary ethosomes was developed in this work. Using this novel method, binary ethosomes containing total alkaloids extracted from Sophora alopecuroides (TASA) were prepared successfully at the temperature below the phase transition temperature (Tc) of the phosphatidyl choline (PC). Several factors affecting this method were investigated. The qualities of the TASA binary ethosomes were characterized by the shape, particle size, and encapsulation efficiency (EE). The percutaneous absorption study of TASA binary ethosomes was performed using confocal laser scanning microscopy and Franz diffusion cells. The results showed that more than 90% sophoridine, 47% matrine, 35% sophocarpine, and 32% lemannine in TASA were entrapped within 1 h at 40°C, with an efficiency improvement of 8.87, 8.10, 7.63, and 7.78-fold than those observed in passive loading method. Transdermal experiments showed that the penetration depth and fluorescence intensity of Rhodamine B from binary ethosome prepared by pH gradient active loading method were much greater than that from binary ethosome prepared by passive loading method or hydroalcoholic solution. These results suggested transmembrane pH gradient active loading method may be an effective method to prepare alkaloids ethosomal systems at the temperatures below the Tc of PC.

  5. Structure of nanocomposites of Al–Fe alloys prepared by mechanical alloying and rapid solidification processing

    Indian Academy of Sciences (India)

    S S Nayak; B S Murty; S K Pabi

    2008-06-01

    Structures of Al-based nanocomposites of Al–Fe alloys prepared by mechanical alloying (MA) and subsequent annealing are compared with those obtained by rapid solidification processing (RSP). MA produced only supersaturated solid solution of Fe in Al up to 10 at.% Fe, while for higher Fe content up to 20 at.% the nonequilibrium intermetallic Al5Fe2 appeared. Subsequent annealing at 673 K resulted in more Al5Fe2 formation with very little coarsening. The equilibrium intermetallics, Al3Fe (Al13Fe4), was not observed even at this temperature. In contrast, ribbons of similar composition produced by RSP formed fine cellular or dendritic structure with nanosized dispersoids of possibly a nano-quasicrystalline phase and amorphous phase along with -Al depending on the Fe content in the alloys. This difference in the product structure can be attributed to the difference in alloying mechanisms in MA and RSP.

  6. Quantum state specific reactant preparation in a molecular beam by rapid adiabatic passage

    Energy Technology Data Exchange (ETDEWEB)

    Chadwick, Helen, E-mail: helen.chadwick@epfl.ch; Hundt, P. Morten; Reijzen, Maarten E. van; Yoder, Bruce L.; Beck, Rainer D. [Laboratoire de Chimie Physique Moléculaire, Ecole Polytechnique Fédérale de Lausanne, Lausanne (Switzerland)

    2014-01-21

    Highly efficient preparation of molecules in a specific rovibrationally excited state for gas/surface reactivity measurements is achieved in a molecular beam using tunable infrared (IR) radiation from a single mode continuous wave optical parametric oscillator (cw-OPO). We demonstrate that with appropriate focusing of the IR radiation, molecules in the molecular beam crossing the fixed frequency IR field experience a Doppler tuning that can be adjusted to achieve complete population inversion of a two-level system by rapid adiabatic passage (RAP). A room temperature pyroelectric detector is used to monitor the excited fraction in the molecular beam and the population inversion is detected and quantified using IR bleaching by a second IR-OPO. The second OPO is also used for complete population transfer to an overtone or combination vibration via double resonance excitation using two spatially separated RAP processes.

  7. Iron Oxide Films Prepared by Rapid Thermal Processing for Solar Energy Conversion

    Science.gov (United States)

    Wickman, B.; Bastos Fanta, A.; Burrows, A.; Hellman, A.; Wagner, J. B.; Iandolo, B.

    2017-01-01

    Hematite is a promising and extensively investigated material for various photoelectrochemical (PEC) processes for energy conversion and storage, in particular for oxidation reactions. Thermal treatments during synthesis of hematite are found to affect the performance of hematite electrodes considerably. Herein, we present hematite thin films fabricated via one-step oxidation of Fe by rapid thermal processing (RTP). In particular, we investigate the effect of oxidation temperature on the PEC properties of hematite. Films prepared at 750 °C show the highest activity towards water oxidation. These films show the largest average grain size and the highest charge carrier density, as determined from electron microscopy and impedance spectroscopy analysis. We believe that the fast processing enabled by RTP makes this technique a preferred method for investigation of novel materials and architectures, potentially also on nanostructured electrodes, where retaining high surface area is crucial to maximize performance. PMID:28091573

  8. Cellulose acetate fibers prepared from different raw materials with rapid synthesis method.

    Science.gov (United States)

    Chen, Jinghuan; Xu, Jikun; Wang, Kun; Cao, Xuefei; Sun, Runcang

    2016-02-10

    Transesterification is a mild process to prepare cellulose acetate (CA) as compared with the traditional method. In this study, CA fibers were produced from six cellulose raw materials based on a simple and rapid transesterification method. The properties of the CA solutions and the obtained CA fibers were investigated in detail. Results showed that all of the cellulose raw materials were esterified within 15 min, and spinning dopes could be obtained by concentrating the CA solutions via vacuum distillation. The XRD, FT-IR, (1)H, (13)C and HSQC NMR analysis confirmed the successful synthesis of CA. The degree of substitution (DS) of the obtained CA was significantly affected by the degree of polymerization (DP) of cellulose raw materials, which further influenced the viscosity of CA solutions as well as the structural, thermal and mechanical properties of the CA fibers.

  9. Preparation and microstructure of Al-Ni-Y powder by rapid solidification

    Institute of Scientific and Technical Information of China (English)

    黄劲松; 刘咏; 陈仕奇; 刘祖铭

    2004-01-01

    The Al-Ni Y alloy powder was prepared by rapid solidification technology of inert gas atomization. The diameter of amorphous powder is less than 12 μm. The effects of atomization gas on cooling velocity, morphology,microstructure and microhardness of powder and fine powder ratio were investigated. The results show that the mor-phology, microstructure and microhardness of powder and fine powder ratio are affected by cooling velocity changed through atomization gas. The cooling velocity of inert gas atomization is more than 1 × 104 K/s. The larger the cool-ing velocity, the finer the powder, and the smoother the surface of powder; the smaller the diameter of powder, the larger the microhardness of powder.

  10. Iron Oxide Films Prepared by Rapid Thermal Processing for Solar Energy Conversion

    Science.gov (United States)

    Wickman, B.; Bastos Fanta, A.; Burrows, A.; Hellman, A.; Wagner, J. B.; Iandolo, B.

    2017-01-01

    Hematite is a promising and extensively investigated material for various photoelectrochemical (PEC) processes for energy conversion and storage, in particular for oxidation reactions. Thermal treatments during synthesis of hematite are found to affect the performance of hematite electrodes considerably. Herein, we present hematite thin films fabricated via one-step oxidation of Fe by rapid thermal processing (RTP). In particular, we investigate the effect of oxidation temperature on the PEC properties of hematite. Films prepared at 750 °C show the highest activity towards water oxidation. These films show the largest average grain size and the highest charge carrier density, as determined from electron microscopy and impedance spectroscopy analysis. We believe that the fast processing enabled by RTP makes this technique a preferred method for investigation of novel materials and architectures, potentially also on nanostructured electrodes, where retaining high surface area is crucial to maximize performance.

  11. Preparation and Swelling Behaviors of Rapid Responsive Semi-IPN NaCMC/PNIPAm Hydrogels

    Institute of Scientific and Technical Information of China (English)

    YI Guobin; HUANG Yunwei; XIONG Fuhua; LIAO Bing; YANG Jin; CHEN Xudong

    2011-01-01

    Semi-interpenetrating network(semi-IPN) hydrogels composed of sodium carboxylmethyl cellulose(NaCMC) and poly N-isopropylacrylamide(PNIPAm) were prepared by free radical polymerization of N-isopropyl acrylamide(NIPAm) in dimethylsulfoxide(DMSO) in the presence of NaCMC.The structures of hydrogels were characterized by Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy(SEM) and differential scanning calorimetry(DSC).SEM images show that the hydrogels present porous network structures.Most water in the hydrogels were free water and freezing water.The equilibrium swelling ratio(ESR) and swelling rate(SR) were quite different at various swelling temperature.ESR of the hydrogels ranged abruptly from 15.2 g/g to 1.56 g/g and the hydrogels changed from transparent into opaque with swelling temperature changing from 33 ℃ to 34 ℃,that is to say,the hydrogels exhibited the good temperature sensitivity at about 33 C similar to low critical solution temperature(LCST) of pure PNIPAm,swelling rate were very different at below and above LCST due to hydrogel swelling with different swelling mechanism.Moreover,the semi-IPN hydrogels swelled much rapidly than pure PNIPAm hydrogels did at room temperature,the equillibrium swelling ratio(ESR) and swelling rate of the hydrogels increased with increasing of NaCMC content,i e.It is suggested that NaCMC could be potential for preparation of porous and rapid swelling hydrogels

  12. Rapid separation of desloratadine and related compounds in solid pharmaceutical formulation using gradient ion-pair chromatography.

    Science.gov (United States)

    Zheng, Jinjian; Rustum, Abu M

    2010-01-01

    We reported the development of an ion-pair chromatographic method to separate desloratadine and all known related compounds in Clarinex Tablets, which use desloratadine as active pharmaceutical ingredient (API). For the first time, baseline separation for desloratadine and all known related compounds was achieved by utilizing a YMC-Pack Pro C(18) column (150 mm x 4.6 mm I.D., 3 microm particle size, 120A pore size) and a gradient elution method. The mobile phase A contains 3 mM sodium dodecylsulfate (SDS), 15 mM sodium citrate buffer at pH 6.2, and 40 mM sodium sulfate, while the mobile phase B is acetonitrile. Chromsword, an artificial intelligence method development tool, was used to optimize several key chromatographic parameters simultaneously including buffer pH/solvent strength, and temperature/gradient profile. The resolution of desloratadine and desloratadine 3,4-dehydropiperidine derivative, one of the critical pairs was improved by adding 40 mM sodium sulfate. Ultraviolet detection at 267 nm was used to achieve the detection for desloratadine and all compounds. This method has been successfully validated according to ICH guidelines in terms of linearity, accuracy, quantitation limit/detection limit, precision, specificity and robustness. It could be used as a stability indicating method for desloratadine drug substances or drug products that use desloratadine as active pharmaceutical ingredient.

  13. Microstructures of FeSi2 based thermoelectric materials prepared by rapid solidification and hot pressing

    Institute of Scientific and Technical Information of China (English)

    Haiyan Chen; Xinbing Zhao; Eckhard Mueller; Yufeng Lu; Cestmir Drasar; Antje Mrotzek

    2004-01-01

    FeSi2 based thermoelectric materials have been prepared by melt spinning and vacuum hot pressing. Most of the rapidly solidified (melt spinning) powders are thin flakes with a thickness less than 0.1 mm. Scanning electron microscope (SEM) surface profiles show there are further finer grain structures with the characteristic size of about 100 nm in a flake. The samples obtained by hot uniaxial pressing (HUP) in vacuum have densities higher than 90% the theoretical density of the materials. It was found by SEM observations that the microstructures are very different for vertical and parallel sections of the HUP samples. X-ray diffraction (XRD)analyses show there are some texture features in the samples. It is considered that the textures of the samples are originated from the orientation of the flakes that tended to align perpendicular to the hot press axis. WSi2 was introduced into the powders unexpectedly during melting process before the rapid solidification, but it makes the microstructures more easily to be explained.

  14. Application of a chromatography model with linear gradient elution experimental data to the rapid scale-up in ion-exchange process chromatography of proteins.

    Science.gov (United States)

    Ishihara, Takashi; Kadoya, Toshihiko; Yamamoto, Shuichi

    2007-08-24

    We applied the model described in our previous paper to the rapid scale-up in the ion exchange chromatography of proteins, in which linear flow velocity, column length and gradient slope were changed. We carried out linear gradient elution experiments, and obtained data for the peak salt concentration and peak width. From these data, the plate height (HETP) was calculated as a function of the mobile phase velocity and iso-resolution curve (the separation time and elution volume relationship for the same resolution) was calculated. The scale-up chromatography conditions were determined by the iso-resolution curve. The scale-up of the linear gradient elution from 5 to 100mL and 2.5L column sizes was performed both by the separation of beta-lactoglobulin A and beta-lactoglobulin B with anion-exchange chromatography and by the purification of a recombinant protein with cation-exchange chromatography. Resolution, recovery and purity were examined in order to verify the proposed method.

  15. Preparation of nanoparticles of Magnolia bark extract by rapid expansion from supercritical solution into aqueous solutions.

    Science.gov (United States)

    He, Shuai; Zhou, Benjie; Zhang, Shouyao; Lei, Zhengjie; Zhang, Zhongyi

    2011-01-01

    A rapid expansion from supercritical solution into aqueous solution (RESSAS) technology was presented for the micronization of Chinese medicinal material. Magnolia bark extract (MBE) obtained by supercritical carbon dioxide (scCO₂) extraction technology was chosen as the experimental material. RESSAS process produced 303.0 nm nanoparticles (size distribution, 243.6-320.5 nm), which was significantly smaller than the 55.3 µm particles (size distribution, 8.3-102.4 µm) prepared by conventional mechanical milling. The effect of process parameters, including extraction temperature (30 °C, 40 °C, 50 °C), extraction pressure (200, 250, 300 bar) and nozzle size (50, 100, 200 µm), on the size distribution of nanoparticles was investigated. The characteristics of nanoparticles and materials were also studied by scanning electron microscopy (SEM) and laser light scattering (LLS). This study demonstrates that RESSAS is applicable for preparing nanoparticles of MBE at low operating temperature; the process is simple without any residual solvent.

  16. Preparation of ZnO Photocatalyst for the Efficient and Rapid Photocatalytic Degradation of Azo Dyes

    Science.gov (United States)

    Chen, Xiaoqing; Wu, Zhansheng; Liu, Dandan; Gao, Zhenzhen

    2017-02-01

    Zinc oxide (ZnO) photocatalysts were synthesized by sol-gel method using zinc acetate as precursor for degradation of azo dyes under UV irradiation. The resultant samples were characterized by different techniques, such as XRD, SEM, and EDX. The influence of preparation conditions such as calcination temperature and composite ratio on the degradation of methyl orange (MO) was investigated. ZnO prepared with a composite ratio of 4:1 and calcination temperature of 400 °C exhibited 99.70% removal rate for MO. The effect of operation parameters on the degradation was also studied. Results showed that the removal rate of azo dyes increased with the increased dosage of catalyst and decreased initial concentration of azo dyes and the acidic condition is favorable for degradation. Furthermore, the kinetics and scavengers of the reactive species during the degradation were also investigated. It was found that the degradation of azo dyes fitted the first-order kinetics and superoxide ions were the main species. The proposed photocatalyst can efficiently and rapidly degrade azo dyes; thus, this economical and environment-friendly photocatalyst can be applied to the treatment of wastewater contaminated with synthetic dyes.

  17. Rapid preparation of polonium counting sources for alpha spectrometry using copper sulfide microprecipitation.

    Science.gov (United States)

    Guérin, Nicolas; Dai, Xiongxin

    2013-07-02

    Thin-layer polonium (Po) sources for alpha spectrometry counting can be rapidly prepared using copper sulfide (CuS) microprecipitation. Polonium was coprecipitated with CuS, filtered onto Eichrom Resolve filters, and counted. This simple procedure is faster, cheaper, and more convenient than traditional spontaneous plating on metallic discs, and similar yields were obtained (80-90%). The experimental conditions for the microprecipitation technique were optimized (0.05 mg of Cu(2+) in 10 mL of 1 M HCl); these compare advantageously with conventional preparation and purification procedures for polonium samples (0.1 to 1 M HCl). The results showed that the most likely potential radionuclide interferences (Ra, Th, U, Np, Pu, and Am) for long-lived polonium isotopes ((208)Po, (209)Po, (210)Po) are effectively removed during processing. The effects of several transition metals (Cu(2+), Ag(+), Fe(3+), Fe(2+), Pb(2+), and Ni(2+)) on the yield and the resolution of the alpha peaks obtained were also assessed. Little interference was found, demonstrating the versatility of the present microprecipitation technique for environmental and biological matrices. The procedure has been successfully applied to different amounts of (210)Po using (209)Po as a yield tracer.

  18. Expression and purification of human ARP1 protein and rapid preparation of polyclonal antibody.

    Science.gov (United States)

    Sun, Mingjuan; Zou, Rongjiang; Dong, Xiaoyi; Zong, Ying; Gao, Yun; Wang, Lianghua; Jiao, Binghua

    2013-01-01

    Angiopoietin-related protein 1 (ARP1) is one of the antiangiogenic factors and plays an important role in endothelial cell proliferation, migration, and blood vessel network formation. Here a rapid method to prepare ARP1 polyclonal antibody in 1 month was developed. The gene of fibrinogen homology domain (FD) for ARP1 was cloned and the protein was expressed in a soluble form of MBP-FD fused protein. The MBP-FD protein was purified using amylose affinity chromatography of maltose-binding protein. Polyclonal antibodies against MBP-FD were obtained through immunization in BALB/c mice. The titer was determined by indirect enzyme-linked immunosorbent assay (ELISA), and the antibody specificity was assessed by Western blot. The full-length ARP1 protein in stable form expressed in transfected human large lung cancer cell lines NCI-H460 was detected by immunocytochemistry (ICC) analysis using ARP1 polyclonal antibodies. The result shows that the antibody possesses good specificity and sensitivity. This work provides a substantial base for the further studies of ARP1 function and associated mechanisms. Supplemental materials are available for this article. Go to the publisher's online edition of Preparative Biochemistry and Biotechnology to view the supplemental file.

  19. Rapid Measurement of Food Adulteration with Minimal Sample Preparation and No Chromatography Using Ambient Ionization Mass Spectrometry.

    Science.gov (United States)

    Dalmia, Avinash

    2017-03-01

    A rapid method, with minimal sample preparation and no chromatography, was developed for analyzing food samples such as olive oil and pomegranate juice to measure adulteration with cheaper ingredients using the novel Direct Sample Analysis™ (DSA) ion source in conjunction with a time-of-flight (TOF)-MS. In less than 30 s, with minimal sample preparation and method development, adulteration of olive oil and pomegranate juice with cheaper seed oils and fruit juices, respectively, was measured with DSA/TOF-MS.

  20. Preparation and rapid analysis of antibacterial silver, copper and zinc doped sol-gel surfaces.

    Science.gov (United States)

    Jaiswal, Swarna; McHale, Patrick; Duffy, Brendan

    2012-06-01

    The colonisation of clinical and industrial surfaces with microorganisms, including antibiotic-resistant strains, has promoted increased research into the development of effective antibacterial and antifouling coatings. This study describes the preparation of metal nitrate (Ag, Cu, Zn) doped methyltriethoxysilane (MTEOS) coatings and the rapid assessment of their antibacterial activity using polyproylene microtitre plates. Microtitre plate wells were coated with different volumes of liquid sol-gel and cured under various conditions. Curing parameters were analysed by thermogravimetric analysis (TGA) and visual examination. The optimum curing conditions were determined to be 50-70°C using a volume of 200 μl. The coated wells were challenged with Gram-positive and Gram-negative bacterial cultures, including biofilm-forming and antibiotic-resistant strains. The antibacterial activities of the metal doped sol-gel, at equivalent concentrations, were found to have the following order: silver>zinc>copper. The order is due to several factors, including the increased presence of silver nanoparticles at the sol-gel coating surface, as determined by X-ray photoelectron spectroscopy, leading to higher elution rates as measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The use of microtitre plates enabled a variety of sol-gel coatings to be screened for their antibacterial activity against a wide range of bacteria in a relatively short time. The broad-spectrum antibacterial activity of the silver doped sol-gel showed its potential for use as a coating for biomaterials.

  1. Facile preparation of a DNA sensor for rapid herpes virus detection

    Energy Technology Data Exchange (ETDEWEB)

    Tam, Phuong Dinh, E-mail: tampd-hast@mail.hut.edu.vn [Hanoi Advanced School of Science and Technology, Hanoi University of Technology (Viet Nam); Tuan, Mai Anh, E-mail: tuanma-itims@mail.hut.edu.vn [International Training Institute for Materials Science, Hanoi University of Technology (Viet Nam); Huy, Tran Quang [National Institute of Hygiene and Epidemiology (NIHE), 01 Yersin, Hai Ba Trung District, Hanoi (Viet Nam); Le, Anh-Tuan [Hanoi Advanced School of Science and Technology, Hanoi University of Technology (Viet Nam); Hieu, Nguyen Van, E-mail: hieu@itims.edu.vn [International Training Institute for Materials Science, Hanoi University of Technology (Viet Nam)

    2010-10-12

    In this paper, a simple DNA sensor platform was developed for rapid herpes virus detection in real samples. The deoxyribonucleic acid (DNA) sequences of the herpes simplex virus (DNA probe) were directly immobilized on the surface of interdigitated electrodes by electrochemical polymerization along with pyrrole monomers. The potential was scanned from - 0.7 to + 0.6 V, and the scanning rate was 100 mV/s. Fourier transform infrared spectroscopy was employed to verify specific DNA sequence binding and the conducting polymer. The morphology of the conducting polymer doped with DNA strands was characterized using a field emission scanning electron microscope. As-obtained DNA sensor was used to detect the herpes virus DNA in the real samples. The results show that the current DNA sensors detected the lowest DNA concentration of 2 nM. This sensitivity appears to be better than that of the DNA sensors prepared by immobilization of the DNA probe on the 3-aminopropyl-triethoxy-silance (APTS) membrane.

  2. Synthesis of Giant Unilamellar Vesicles (GUV) from Liposomes Prepared by the Rapid Solvent Exchange (RSE) Method

    Science.gov (United States)

    Baykal-Caglar, Eda

    2010-10-01

    Lipid bilayers, which is an important constituent of cell membranes, has been extensively studied by biophysicists. Cell membranes perform many vital cell functions such as signal transduction and transportation of materials needed for the functioning of the cell organelles. Understanding the organization and dynamics of lipid bilayers is important for understanding the processes taking place in cell membranes. Giant Unilamellar Vesicles (GUVs) are cell-sized model systems that allow direct visualization of membrane-related phenomena using fluorescence microscopy. In this study, we investigated the synthesis of GUVs from much smaller liposomes (less than 0.5 microns) produced by the Rapid Solvent Exchange (RSE) method in aqueous solutions of high and low ionic strength. The GUVs synthesized using RSE liposomes are more uniform in lipid composition than that synthesized by other methods. We made a number of modifications to the original electroformation method, and we are able to prepare GUVs from RSE liposomes both in high ionic strength and low ionic strength buffers. Using our optimized procedure, we are also able to produce high quality multi-component GUVs to study the dynamics of lipid domains.

  3. Preparation of the New-type Gradient Nuclear Radiation Shielding Material%一种新型梯度防核辐射材料的制备

    Institute of Scientific and Technical Information of China (English)

    马涛; 刘宇艳; 刘振国; 刘少柱; 贾默; 尹松年

    2012-01-01

    A new-type gradient nuclear radiation shielding material was prepared for utilizing Lu203 ,tungsten and polyethylene as main raw materials by mechanical blending method handled with coupling agent, acid and alkali reaction method and in-situ reaction. Afterwards hot-press processing and layered hot-pressing superimposition was used to process materials and then gradient materials were obtained. At last,monolayer and gradient materials were characterized and tested. The results indicated that: the new gradient material had good tensile properties. Meanwhile, beta and gamma rays could be shielded well, it oneself had lead-free poison, the lasting shielding effectiveness, the good comprehensive shielding performance,and it could flexibly adjust the types and the order of monolayer materials for getting corresponding gradient materials according to the specific radiation environment. The gradient materials had a good application future.%以氧化镥、钨、聚乙烯为主要原料,运用偶联剂处理的机械共混法、酸碱反应法、原位反应法制备出一种新型梯度防核辐射材料,测试结果表明:制得的新型梯度防核辐射材料,具有良好的拉伸性能,对口射线、7射线均有很好的屏蔽效果,无铅毒、屏蔽效能持久,综合性能良好。这种梯度材料能根据具体辐射环境灵活调整组成材料的种类与顺序,具有良好的应用价值与使用前景。

  4. Rapid preparation of nuclei-depleted detergent-resistant membrane fractions suitable for proteomics analysis

    Directory of Open Access Journals (Sweden)

    Mukhopadhyay Nishit K

    2008-06-01

    Full Text Available Abstract Background Cholesterol-rich membrane microdomains known as lipid rafts have been implicated in diverse physiologic processes including lipid transport and signal transduction. Lipid rafts were originally defined as detergent-resistant membranes (DRMs due to their relative insolubility in cold non-ionic detergents. Recent findings suggest that, although DRMs are not equivalent to lipid rafts, the presence of a given protein within DRMs strongly suggests its potential for raft association in vivo. Therefore, isolation of DRMs represents a useful starting point for biochemical analysis of lipid rafts. The physicochemical properties of DRMs present unique challenges to analysis of their protein composition. Existing methods of isolating DRM-enriched fractions involve flotation of cell extracts in a sucrose density gradient, which, although successful, can be labor intensive, time consuming and results in dilute sucrose-containing fractions with limited utility for direct proteomic analysis. In addition, several studies describing the proteomic characterization of DRMs using this and other approaches have reported the presence of nuclear proteins in such fractions. It is unclear whether these results reflect trafficking of nuclear proteins to DRMs or whether they arise from nuclear contamination during isolation. To address these issues, we have modified a published differential detergent extraction method to enable rapid DRM isolation that minimizes nuclear contamination and yields fractions compatible with mass spectrometry. Results DRM-enriched fractions isolated using the conventional or modified extraction methods displayed comparable profiles of known DRM-associated proteins, including flotillins, GPI-anchored proteins and heterotrimeric G-protein subunits. Thus, the modified procedure yielded fractions consistent with those isolated by existing methods. However, we observed a marked reduction in the percentage of nuclear proteins

  5. Preparation and laser modulation investigation of quadratic electro-optical crystal Cu:KTN with gradient refractivity effect

    Science.gov (United States)

    Wang, Xuping; Liu, Bing; Yang, Yuguo; Zhang, Yuanyuan; Lv, Xianshun; Wei, Lei; Xu, Jianhua; Ma, Ling; Wang, Jiyang

    2017-06-01

    Copper doped KTN crystals with different doping concentrations were grown by the Czochralski method. The XRD patterns show that all of the crystals are in cubic phase at room temperature. The influences of the CuO doping concentrations on dielectric properties of the crystals were measured. Cu: KTN crystals exhibited color changes depending on the doping concentrations. It was found that the inhomogeneous composition property can be used to form gradient refractivity effect in the case of ion doping. The refractive index gradient reaches 33×10-3/mm for the grown Cu: KTNN crystals. Base on the interaction between the quadratic electro-optic effect and the gradient refractivity effect, the deflection and the intensity of a Cu: KTa0.62Nb0.38O3 sample were modulated in different orientations of the crystal. The deflection efficiency and the half-wave voltage of the modulation are 45 mrad/kV and 75 V, respectively.

  6. Texture control and growth mechanism of WSe2 film prepared by rapid selenization of W film

    Science.gov (United States)

    Li, Hongchao; Gao, Di; Li, Kun; Pang, Mengde; Xie, Senlin; Liu, Rutie; Zou, Jianpeng

    2017-02-01

    The tungsten diselenide (WSe2) films with different orientation present unique properties suitable for specific applications, such as WSe2 with a C-axis⊥substrate for optoelectronics and WSe2 with a C-axis // substrate for electrocatalysts. Orientation control of WSe2 is essential for realizing the practical applications. In this letter, a WSe2 film has been prepared via rapid selenization of a magnetron-sputtered tungsten (W) film. The influence of the magnetron-sputtered W film on WSe2 film growth was studied systematically. Scanning electron microscopy, X-ray diffractometry and high-resolution transmission electron microscopy were used to evaluate the morphology, microstructure and phase composition of the W and WSe2 films. The substrate temperature has a significant effect on the W film phase composition, but little effect on the WSe2 film orientation. The WSe2 orientation can be controlled by changing the W film microstructure. A dense W film that is deposited at low pressure is conducive to the formation of WSe2 with a C-axis⊥substrate, whereas a porous W film deposited at high pressure favors the formation of WSe2 with a C-axis // substrate. A growth model for the WSe2 film with different texture has been proposed based on the experimental results. The direction of selenium (Se) vapor diffusion differs at the top and side surfaces. This is a key factor for the preparation of anisotropic WSe2 films. Highly oriented WSe2 films with a C-axis⊥substrate grow from the dense W film deposited at low pressure because Se vapor can only diffuse into the W film from the top surface where it is converted into selenide. Highly oriented WSe2 with a C-axis // substrate can be achieved for the porous W film that is deposited at high pressure because the nanopores provide a fast transmission tunnel for Se vapor diffusion. These findings will contribute to the controlled fabrication of WSe2 film and provide a theoretical basis for its application.

  7. Preparation and Characterization of Micronized Artemisinin via a Rapid Expansion of Supercritical Solutions (RESS Method

    Directory of Open Access Journals (Sweden)

    Xiaonan Zhang

    2012-04-01

    Full Text Available The particle sizes of pharmaceutical substances are important for their bioavailability. Bioavailability can be improved by reducing the particle size of the drug. In this study, artemisinin was micronized by the rapid expansion of supercritical solutions (RESS. The particle size of the unprocessed white needle-like artemisinin particles was 30 to 1200 µm. The optimum micronization conditions are determined as follows: extraction temperature of 62 °C, extraction pressure of 25 MPa, precipitation temperature 45 °C and nozzle diameter of 1000 μm. Under the optimum conditions, micronized artemisinin with a (mean particle size MPS of 550 nm is obtained. By analysis of variance (ANOVA, extraction temperature and pressure have significant effects on the MPS of the micronized artemisinin. The particle size of micronized artemisinin decreased with increasing extraction temperature and pressure. Moreover, the SEM, LC-MS, FTIR, DSC and XRD allowed the comparison between the crystalline initial state and the micronization particles obtained after the RESS process. The results showed that RESS process has not induced degradation of artemisinin and that processed artemisinin particles have lower crystallinity and melting point. The bulk density of artemisinin was determined before and after RESS process and the obtained results showed that it passes from an initial density of 0.554 to 0.128 g·cm−3 after the processing. The decrease in bulk density of the micronized powder can increase the liquidity of drug particles when they are applied for medicinal preparations. These results suggest micronized powder of artemisinin can be of great potential in drug delivery systems.

  8. A simple and rapid method for the preparation of homologous DNA oligonucleotide hybridization probes from heterologous gene sequences and probes.

    Science.gov (United States)

    Maxwell, E S; Sarge, K D

    1988-11-30

    We describe a simple and rapid method for the preparation of homologous DNA oligonucleotide probes for hybridization analysis and/or cDNA/genomic library screening. With this method, a synthetic DNA oligonucleotide derived from a known heterologous DNA/RNA/protein sequence is annealed to an RNA preparation containing the gene transcript of interest. Any unpaired 3'-terminal oligonucleotides of the heterologous DNA primer are then removed using the 3' exonuclease activity of the DNA Polymerase I Klenow fragment before primer extension/dideoxynucleotide sequencing of the annealed RNA species with AMV reverse transcriptase. From the determined RNA sequence, a completely homologous DNA oligonucleotide probe is then prepared. This approach has been used to prepare a homologous DNA oligonucleotide probe for the successful library screening of the yeast hybRNA gene starting with a heterologous mouse hybRNA DNA oligonucleotide probe.

  9. Rapid Microwave Preparation of Thermoelectric TiNiSn and TiCoSb Half-Heusler Compounds

    Energy Technology Data Exchange (ETDEWEB)

    Birkel, Christina S.; Zeier, Wolfgang G.; Douglas, Jason E.; Lettiere, Bethany R.; Mills, Carolyn E.; Seward, Gareth; Birkel, Alexander; Snedaker, Matthew L.; Zhang, Yichi; Snyder, G. Jeffrey; Pollock, Tresa M.; Seshadri, Ram; Stucky, Galen D. (CIT); (UCSB)

    2012-10-25

    The 18-electron ternary intermetallic systems TiNiSn and TiCoSb are promising for applications as high-temperature thermoelectrics and comprise earth-abundant, and relatively nontoxic elements. Heusler and half-Heusler compounds are usually prepared by conventional solid state methods involving arc-melting and annealing at high temperatures for an extended period of time. Here, we report an energy-saving preparation route using a domestic microwave oven, reducing the reaction time significantly from more than a week to one minute. A microwave susceptor material rapidly heats the elemental starting materials inside an evacuated quartz tube resulting in near single phase compounds. The initial preparation is followed by a densification step involving hot-pressing, which reduces the amount of secondary phases, as verified by synchrotron X-ray diffraction, leading to the desired half-Heusler compounds, demonstrating that hot-pressing should be treated as part of the preparative process. For TiNiSn, high thermoelectric power factors of 2 mW/mK{sup 2} at temperatures in the 700 to 800 K range, and zT values of around 0.4 are found, with the microwave-prepared sample displaying somewhat superior properties to conventionally prepared half-Heuslers due to lower thermal conductivity. The TiCoSb sample shows a lower thermoelectric figure of merit when prepared using microwave methods because of a metallic second phase.

  10. A Rapid Synthetic Method for the Preparation of Two Tris-Cobalt(III) Compounds.

    Science.gov (United States)

    Jackman, Donald C.; Rillema, D. Paul

    1989-01-01

    Reports a method of preparation for tris(ethylenediamine)cobalt(III) and tris(2,2'-bipyridine)cobalt(III) that will shorten the preparation time by approximately 3 hours. Notes the time for synthesis and isolation of compound one was 1 hour (yield 38 percent) while compound two took 50 minutes (yield 71%). (MVL)

  11. A Development of Rapid, Practical and Selective Process for Preparation of Z-Oximes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Bo Ram; Sung, Gi Hyeon; Yoon, Yongjin [Gyeongsang National Univ., Jinju (Korea, Republic of); Kim, Jeumjong [Electronic and Telecommunications Research Institute, Daejeon (Korea, Republic of)

    2013-04-15

    Oximes are important functional groups in organic chemistry due to their synthetic utility as protecting groups for carbonyl groups and their ability to form other functionalities, and their biological activity. Oximes are commonly prepared by condensing aldehydes and ketones with hydroxylamines. These reactions do not always go to completion and reaction times can be long, and therefore there has been interest in more convenient and efficient methods. To avoid the typical disadvantage, conversion of aldehydes and ketones to the corresponding oximes was accomplished by using various catalysts such as organic acid/bases, AcONa, alumina, TiO{sub 2}/SO{sub 4} silica gel, Oxone, NaOH, basic ionic liquid 1-butyl-3-methylimidazolium hydroxide, polyoxometalates, Na{sub 2}SO{sub 4}, and CuSO{sub 4}/K{sub 2}CO{sub 3} under the solvent, the solvent-free or the microwave conditions. These are one and more drowbacks such as long reaction time, use of catalysts, inconvenients due to solid-sate reaction, low yields and limitaion of some carbonyl compounds. On the other hand, H. Sharghi, et al.,14 reported the catalysis of the stereoselectivity of CuSO{sub 4} and K{sub 2}CO{sub 3} in the oximation of aldehydes and ketones under solvent-free conditions. Although this method show high selectivity, it is inconvenient for the large scale experiments and the industrial process due to the solvent-free condition. Therefore, we attempted to develop a more convenient and efficient solution method. According to the literatures, treatment of potassium carbonate with methanol generates slightly the potassium methoxide, which may be useful for forming the free NH{sub 2}OH from its salts. We describe the oximation of aldehyde and ketone using NH{sub 2}OH·HCl/K{sub 2}CO{sub 3} in methanol solvent. We selected oximation of acetophenone (1a) with hydroxylamine hydrochloride as a model and its behavior was investigated in seven solvents involving methanol (Table 1). As shown in the Entry 2 in

  12. Development of a Gradient HPLC Method for the Simultaneous Determination of Sotalol and Sorbate in Oral Liquid Preparations Using Solid Core Stationary Phase

    Directory of Open Access Journals (Sweden)

    Ludmila Matysova

    2015-01-01

    Full Text Available A selective and sensitive gradient HPLC-UV method for quantification of sotalol hydrochloride and potassium sorbate in five types of oral liquid preparations was developed and fully validated. The separation of an active substance sotalol hydrochloride, potassium sorbate (antimicrobial agent, and other substances (for taste and smell correction, etc. was performed using an Ascentis Express C18 (100 × 4.6 mm, particles 2.7 μm solid core HPLC column. Linear gradient elution mode with a flow rate of 1.3 mL min−1 was used, and the injection volume was 5 µL. The UV/Vis absorbance detector was set to a wavelength of 237 nm, and the column oven was conditioned at 25°C. A sodium dihydrogen phosphate dihydrate solution (pH 2.5; 17.7 mM was used as the mobile phase buffer. The total analysis time was 4.5 min (+2.5 min for reequilibration. The method was successfully employed in a stability evaluation of the developed formulations, which are now already being used in the therapy of arrhythmias in pediatric patients; the method is also suitable for general quality control, that is, not only just for extemporaneous preparations containing the mentioned substances.

  13. Short communication: rapid preparation of preventive and therapeutic whole-killed retroviral vaccines using the microbicide taurine chloramine.

    Science.gov (United States)

    Dudani, A K; Martyres, A; Fliss, H

    2008-04-01

    A current urgent priority is to develop microbicides and vaccines to combat retroviruses like human immunodeficiency virus (HIV). We show that the cysteine-selective natural compound, taurine chloramine (T-NCl), can be effective in this task. A number of proteins in all retroviruses contain highly conserved cysteine-rich regions that are essential for infection and replication. Our data show that by targeting these essential cysteine residues, T-NCl (2 or 5 mM) acts as a highly effective and safe microbicide that fully blocks the infectivity of high HIV-1 titers (10(6) TCID(50) units/ml) but is not injurious to eukaryotic cells. We also demonstrate that T-NCl can be used to prepare a highly effective whole-killed vaccine against murine AIDS (MAIDS) that shows both preventive and therapeutic efficacy. The vaccine consists of a T-NCl-inactivated retrovirus suspension in host cell lysate. The novelty of our approach lies in the ease and speed of vaccine preparation and its avoidance of harsh inactivation or purification steps that can alter native viral conformation. Our approach is therefore likely to overcome a number of intractable obstacles to the preparation of an effective whole-killed HIV vaccine, such as surviving infective viral particles, rapid viral mutation rates, numerous viral strains, and harsh purification steps. Our approach may also permit the rapid preparation of autologous, or custom-made, vaccines for individual patients.

  14. A rapid and efficient preparation of [{sup 123}I]radiopharmaceuticals using a small HPLC Rocket[reg] column

    Energy Technology Data Exchange (ETDEWEB)

    Katsifis, Andrew [Radiopharmaceuticals Division R and D, Australian Nuclear Science and Technology, Organisation, Menai, NSW 2234, Sydney (Australia)]. E-mail: akx@ansto.gov.au; Papazian, Vahan [Radiopharmaceuticals Division R and D, Australian Nuclear Science and Technology, Organisation, Menai, NSW 2234, Sydney (Australia); Jackson, Timothy [Radiopharmaceuticals Division R and D, Australian Nuclear Science and Technology, Organisation, Menai, NSW 2234, Sydney (Australia); Loc' h, Christian [Radiopharmaceuticals Division R and D, Australian Nuclear Science and Technology, Organisation, Menai, NSW 2234, Sydney (Australia)

    2006-01-01

    A simplified method for the rapid and efficient preparation of [{sup 123}I]radiopharmaceuticals is described. Three radiopharmaceuticals, [{sup 123}I]{beta}-CIT, [{sup 123}I]MIBG and [{sup 123}I]clioquinol, were synthesised and purified as model compounds. The radiotracers were labelled with iodine-123 using electrophilic oxidative conditions and purified by a compact semi-preparative reverse phase column (C-18, 3 {mu}m, 7x53 mm, Alltima Rocket[reg, Alltech] using aqueous-ethanol as HPLC solvents that were directly used for radiopharmaceutical formulation. The radiochemical purity of the radioiodinated tracers as assessed by analytical HPLC was higher than 99% with specific activity higher than 3 GBq/nmol. The total preparation time of a radiotracer ranged from 40 to 60 min and, starting from 3.7 GBq of iodine-123, more than 2.5 GBq of formulated radiopharmaceuticals were available for clinical investigations.

  15. A Rapid and Simple Approach to Preparation of Monoclonal Antibody Based on DNA Immunization

    Institute of Scientific and Technical Information of China (English)

    YiNi; KeMa; JingNi; XiujuanZheng; YingWang; SidongXiong

    2004-01-01

    Inoculation with purified specific protein is usually the first step for preparation of monoclonal antibody (mAb). But it is quite difficult to obtain pure proteins especially with natural structures. Here we attempt to replace the protein inoculation with DNA immunization in the preparation of mAb. The eukaryotic expression vectors pcDNA3-PreS2/S and pVAX-PreS2/S encoding the HBV M protein were constructed and prepared for DNA immunization. Female BALB/c mice developed a well antibody response to the target antigen after muscle injection with corresponding plasmids. The mice with effective antibodies induced were used for preparation of mAb. We found the mice immunized with three administrations of pcDNA3-PreS2/S and boosted by intrasplenic injection with the same plasmid could be exploited for preparation of mAb. And positive hybridoma cell 2D3 that can secrete specific mAb was cloned and analyzed. Our studies demonstrate that gene immunization may provide a convenient and efficient way to prepare mAbs. Cellular & Molecular Immunology.

  16. A Rapid and Simple Approach to Preparation of Monoclonal Antibody Based on DNA Immunization

    Institute of Scientific and Technical Information of China (English)

    Yi Ni; Ke Ma; Jing Ni; Xiujuan Zheng; Ying Wang; Sidong Xiong

    2004-01-01

    Inoculation with purified specific protein is usually the first step for preparation of monoclonal antibody (mAb).But it is quite difficult to obtain pure proteins especially with natural structures. Here we attempt to replace the protein inoculation with DNA immunization in the preparation of mAb. The eukaryotic expression vectors pcDNA3-PreS2/S and pVAX-PreS2/S encoding the HBV M protein were constructed and prepared for DNA immunization. Female BALB/c mice developed a well antibody response to the target antigen after muscle injection with corresponding plasmids. The mice with effective antibodies induced were used for preparation of mAb. We found the mice immunized with three administrations of pcDNA3-PreS2/S and boosted by intrasplenic injection with the same plasmid could be exploited for preparation of mAb. And positive hybridoma cell 2D3 that can secrete specific mAb was cloned and analyzed. Our studies demonstrate that gene immunization may provide a convenient and efficient way to prepare mAbs.

  17. Preparation of Ultrahigh Potential Gradient of ZnO Varistors by Rare-Earth Doping and Low-Temperature Sintering

    Directory of Open Access Journals (Sweden)

    Lei Ke

    2013-01-01

    Full Text Available The effects of rare-earth doping and low-temperature sintering on electrical properties of ZnO varistors were investigated. The potential gradient (E1mA of the ZnO varistors increased significantly to 2247.2 V/mm after doping 0.08 mol% of Y2O3 and sintering at 800°C for 2 h. The notable decrease of the grain size with the given experimental conditions was the origin for the increase in E1mA. During the process of high-temperature sintering, both the oxygen at the grain boundary interface and the neutralisation of the ions on the depletion layer were directly reduced, which caused the weight loss and the internal derangement of double Schottky barriers.

  18. A simple improved desolvation method for the rapid preparation of albumin nanoparticles.

    Science.gov (United States)

    Jahanban-Esfahlan, Ali; Dastmalchi, Siavoush; Davaran, Soodabeh

    2016-10-01

    The current study tried to establish a simple and fast method for the preparation of BSA and HSA nanoparticles, based on an improved desolvation procedure under the aspect of a controllable particle size around 100nm for drug delivery applications. The Procedure used for the nanoparticles preparation was simplified by using a designed apparatus for controlling the addition of ethanol and it was used instead of conventional tubing pump which enabled the preparation of nanoparticles under defined conditions. By using EDC as cross-linker instead of glutharaldehyde, the time of nanoparticles preparation procedure was reduced to 3h. Several factors of the preparation process, such as the volume of the albumin solution, desolvating agent volume, the amount of cross-linker, the presence of salts and protein concentration were evaluated. Nanoparticles with smaller size were obtained under experimental conditions without the presence of salts or the use of buffers, 250mg of protein/4ml water, 5mg cross-linker, the addition of 4 and 8ml ethanol by using the designed apparatus to the HSA and BSA solution, respectively. By using this improved method, BSA and HSA nanoparticles of the size around 100nm and polydispersity below 0.2 were obtained.

  19. A Simple and Rapid Method for Standard Preparation of Gas Phase Extract of Cigarette Smoke

    Science.gov (United States)

    Higashi, Tsunehito; Mai, Yosuke; Noya, Yoichi; Horinouchi, Takahiro; Terada, Koji; Hoshi, Akimasa; Nepal, Prabha; Harada, Takuya; Horiguchi, Mika; Hatate, Chizuru; Kuge, Yuji; Miwa, Soichi

    2014-01-01

    Cigarette smoke consists of tar and gas phase: the latter is toxicologically important because it can pass through lung alveolar epithelium to enter the circulation. Here we attempt to establish a standard method for preparation of gas phase extract of cigarette smoke (CSE). CSE was prepared by continuously sucking cigarette smoke through a Cambridge filter to remove tar, followed by bubbling it into phosphate-buffered saline (PBS). An increase in dry weight of the filter was defined as tar weight. Characteristically, concentrations of CSEs were represented as virtual tar concentrations, assuming that tar on the filter was dissolved in PBS. CSEs prepared from smaller numbers of cigarettes (original tar concentrations ≤15 mg/ml) showed similar concentration-response curves for cytotoxicity versus virtual tar concentrations, but with CSEs from larger numbers (tar ≥20 mg/ml), the curves were shifted rightward. Accordingly, the cytotoxic activity was detected in PBS of the second reservoir downstream of the first one with larger numbers of cigarettes. CSEs prepared from various cigarette brands showed comparable concentration-response curves for cytotoxicity. Two types of CSEs prepared by continuous and puff smoking protocols were similar regarding concentration-response curves for cytotoxicity, pharmacology of their cytotoxicity, and concentrations of cytotoxic compounds. These data show that concentrations of CSEs expressed by virtual tar concentrations can be a reference value to normalize their cytotoxicity, irrespective of numbers of combusted cigarettes, cigarette brands and smoking protocols, if original tar concentrations are ≤15 mg/ml. PMID:25229830

  20. Rapid preparation of ceramic moulds for medium-sized superalloy castings with magnesia-phosphate-bonded bauxite-mullite investments

    Directory of Open Access Journals (Sweden)

    Li Tingzhong

    2010-11-01

    Full Text Available Phosphate-bonded investments have already been widely utilized in dental restoration and micro-casting of artistic products for its outstanding rapid setting and high strength. However, the rapid setting rate of investment slurry has up to now been a barrier to extend the use of such slurry in preparation of medium-sized ceramic moulds. This paper proposes a new process of rapid fabrication of magnesia-phosphate-bonded investment ceramic moulds for medium-sized superalloy castings utilizing bauxite and mullite as refractory aggregates. In order to determine the properties of magnesia-phosphate-bonded bauxite-mullite investments (MPBBMI, a series of experiments were conducted, including modification of the workable time of slurry by liquid(mL/powder(g(L/P ratio and addition of boric acid as retard agent and sodium tri-polyphosphate (STP as strengthening agent, and adjustment of bauxite (g/mullite(g(B/M ratio for mechanical strength. Mechanical vibration was applied to improve initial setting time and fluidity when pouring investment slurry; then an intermediate size ceramic mould for superalloy castings was manufactured by means of this rapid preparing process with MPBBMI material. The results showed that the MPBBMI slurry exhibits proper initial setting time and excellent fluidity when the L/P ratio is 0.64 and the boric acid content is 0.88wt.%. The fired specimens made from the MPBBMI material demonstrated adequate compression strength to withstand impact force of molten metal when the B/M ratio is 0.89 and the STP content is 0.92wt.%. The experimental results confirmed the feasibility of the proposed rapid fabricating process for medium-sized ceramic moulds with MPBBMI material by appropriate measures.

  1. A homogeneous, high-throughput assay for phosphatidylinositol 5-phosphate 4-kinase with a novel, rapid substrate preparation.

    Directory of Open Access Journals (Sweden)

    Mindy I Davis

    Full Text Available Phosphoinositide kinases regulate diverse cellular functions and are important targets for therapeutic development for diseases, such as diabetes and cancer. Preparation of the lipid substrate is crucial for the development of a robust and miniaturizable lipid kinase assay. Enzymatic assays for phosphoinositide kinases often use lipid substrates prepared from lyophilized lipid preparations by sonication, which result in variability in the liposome size from preparation to preparation. Herein, we report a homogeneous 1536-well luciferase-coupled bioluminescence assay for PI5P4Kα. The substrate preparation is novel and allows the rapid production of a DMSO-containing substrate solution without the need for lengthy liposome preparation protocols, thus enabling the scale-up of this traditionally difficult type of assay. The Z'-factor value was greater than 0.7 for the PI5P4Kα assay, indicating its suitability for high-throughput screening applications. Tyrphostin AG-82 had been identified as an inhibitor of PI5P4Kα by assessing the degree of phospho transfer of γ-(32P-ATP to PI5P; its inhibitory activity against PI5P4Kα was confirmed in the present miniaturized assay. From a pilot screen of a library of bioactive compounds, another tyrphostin, I-OMe tyrphostin AG-538 (I-OMe-AG-538, was identified as an ATP-competitive inhibitor of PI5P4Kα with an IC(50 of 1 µM, affirming the suitability of the assay for inhibitor discovery campaigns. This homogeneous assay may apply to other lipid kinases and should help in the identification of leads for this class of enzymes by enabling high-throughput screening efforts.

  2. Preparing a paper for publication: an action plan for rapid composition and completion

    NARCIS (Netherlands)

    Harvey, J.A.

    2009-01-01

    An important challenge for scientists, especially those early in their careers, is preparing an effective article for submission to a peer-reviewed journal. Here, I present a number of suggestions on how it could be accomplished. This action plan addresses (1) how to approach a topic by developing a

  3. Repair of the radial defect of rabbit with polyester/tricalcium phosphate scaffolds prepared by rapid prototyping technology

    Institute of Scientific and Technical Information of China (English)

    SUN Liang; HU Yun-yu; XIONG Zhuo; WANG Wan-ming; PAN Yu

    2006-01-01

    Objective: To evaluate the effects of repairing rabbit radial defects with polyester/tricalcium phosphate scaffolds prepared by rapid prototyping technology loaded with bovine bone morphogenetic protein (bBMP), and find new carriers for growth factors.Methods: Polyester/tricalcium phosphate scaffolds prepared by rapid prototyping technology loaded with and without bovine BMP were used to repair the 15 mm radial defect in rabbit. Then the results of radiography,histology, scaffolds degrade rates and bone mineral density(BMD) were appraised to examine the effects at the 12th week.Results: At the 12th week postoperatively, all defects treated with bBMP were radiographically repaired. No radius implanted polyester/tricalcium phosphate scaffolds without bBMP showed radiographic and histological union.At experimental groups, longitudinal alignment of lamellar structure was observed histologically at the 12th week,indicating that remodeling of regenerated bone was complete in different degree. Of the three experimental groups, the bony regeneration and remodeling of callus in poly lactide-co-glycolide/tricalcium phosphate (PLGA/TCP) group was the best. The BMD values were beyond 70% of normal value at the 12th week while the PLGA/TCP scaffolds group was the highest, and no abnormalities were observed in the surrounding soft tissue in all groups.Conclusions : Polyester/tricalciumphosphatescaffolds prepared by rapid prototyping technology loaded with bovine BMP can repair a 15 mm radial defect of rabbit. As for the results, the PLGA/TCP scaffold is ideal and better than poly L-lactide-co-D, L-lactide (PDLLA/TCP)scaffold, but the ploy L-lactic acid (PLLA/TCP) is not so good for its low degradation rates.

  4. Rapid molecular diagnostic test for Zika virus with low demands on sample preparation and instrumentation.

    Science.gov (United States)

    Eboigbodin, Kevin E; Brummer, Mirko; Ojalehto, Tuomas; Hoser, Mark

    2016-12-01

    Zika virus has only recently gained attention due to recent large outbreaks worldwide. An easy to use nucleic acid amplification test could play an important role in the early detection of the infection and patient management. Here, we report a rapid and robust isothermal nucleic acid amplification assay for the detection of Zika virus. The method is cost-effective and compatible with portable instrumentation, enabling near patient testing and field use.

  5. Multiband Transport in CoSb3 Prepared by Rapid Solidification.

    Science.gov (United States)

    Ikeda, Matthias; Tomeš, Petr; Prochaska, Lukas; Eilertsen, James; Populoh, Sascha; Löffler, Stefan; Svagera, Robert; Waas, Monika; Sassik, Herbert; Weidenkaff, Anke; Paschen, Silke

    2015-09-01

    Nano-grained CoSb3 was prepared by melt-spinning and subsequent spark plasma sintering. The phonon thermal conductivity of skutterudites is known to be sensitive to the kind and the amount of guest atoms. Thus, unfilled CoSb3 can serve as model compound to study the impact of a nanostructure on the thermoelectric properties, especially the phonon thermal conductivity. Therefore, a series of materials was prepared differing only by the cooling speed during the quenching procedure. In contrast to clathrates, the microstructure of meltspun CoSb3 was found to be sensitive to the cooling speed. Although the phonon thermal conductivity, studied by means of Flash and 3ω measurements, was found to be correlated with the grain size, the bulk density of the sintered materials had an even stronger impact. Interestingly, the reduced bulk density did not result in an increased electrical resistivity. The influence of Sb and CoSb2 as foreign phase on the electronic properties of CoSb3 was revealed by a multi-band Hall effect analysis. While CoSb2 increases the charge carrier density, the influence of the highly mobile charge carriers introduced by elemental Sb on the thermoelectric properties of the composite offer an interesting perspective for the preparation of efficient thermoelectric composite materials.

  6. A Plasma-Assisted Route to the Rapid Preparation of Transition-Metal Phosphides for Energy Conversion and Storage

    KAUST Repository

    Liang, Hanfeng

    2017-06-06

    Transition-metal phosphides (TMPs) are important materials that have been widely used in catalysis, supercapacitors, batteries, sensors, light-emitting diodes, and magnets. The physical and chemical structure of a metal phosphide varies with the method of preparation as the electronic, catalytic, and magnetic properties of the metal phosphides strongly depend on their synthesis routes. Commonly practiced processes such as solid-state synthesis and ball milling have proven to be reliable routes to prepare TMPs but they generally require high temperature and long reaction time. Here, a recently developed plasma-assisted conversion route for the preparation of TMPs is reviewed, along with their applications in energy conversion and storage, including water oxidation electrocatalysis, sodium-ion batteries, and supercapacitors. The plasma-assisted synthetic route should open up a new avenue to prepare TMPs with tailored structure and morphology for various applications. In fact, the process may be further extended to the synthesis of a wide range of transition-metal compounds such as borides and fluorides at low temperature and in a rapid manner.

  7. Preparation of a novel magnetic powder resin for the rapid removal of tetracyclinein the aquatic environment

    Institute of Scientific and Technical Information of China (English)

    Qing Zhou; Man Cheng Zhang; Chen Dong Shuang; Zhe Qin Li; Ai Min Li

    2012-01-01

    Magnetic powder resin Q150 with high specific surface area of 1074 m2/g was prepared by the membrane emulsificationsuspension polymerization technique.Adsoption of tetracycline on the obtained sorbent Q150 was evaluted by using the granule resin (GR) XAD-4,the powder activated carbon (PAC) 1240AC and the granule activated carbon (GAC) HD4000 for comparison.It was found that Q150 had a larger adsorption capacity,faster kinetic and easier regeneration under alkaline condition.The results suggested that the powder resin (PR) Q150 would be a promising sorbent for removing antibiotics and even other organic micropollutants from the aquatic environment.

  8. Preparation and in vitro evaluation of liposomal chloroquine diphosphate loaded by a transmembrane pH-gradient method.

    Science.gov (United States)

    Qiu, Liyan; Jing, Na; Jin, Yi

    2008-09-01

    This study developed an active loading method for encapsulating chloroquine diphosphate (CQ) into liposomes. The effects of different formulation factors on the encapsulation efficiency (EE) and the size of CQ liposomes were investigated. These factors included the internal phase of liposomes, the external phase of liposomes, the ratio of drug to soybean phosphatidylcholine (drug/SPC), the ratio of cholesterol to soybean phosphatidylcholine (Chol/SPC), and the incubation temperature and time. The EE (93%) was obtained when using drug/SPC (1:50 mass ratio), SPC/Chol (1:5 mass ratio) at 0.10 M citrate-sodium citrate buffer (pH 3.6). As 5 mol% methoxypoly(ethylene glycol)(2,000) cholesteryl succinate (CHS-PEG(2000)) or distearoyl phosphatidylethanolamine-poly (ethylene glycol)(2,000) (DSPE-PEG(2000)) was added, the size of particle was reduced and the EE was improved. Freeze-drying with 5% trehalose as a cryoprotectant was carried out to achieve long-term stability. The drug release studies were performed in vitro simulating the desired application conditions, such as physiological fluids (pH 7.4), tumor tissues (pH 6.5) and endosomal compartments (pH 5.5). The release of CQ from the liposomes prepared via remote loading showed the significant pH-sensitivity and retention properties, which favored the application of liposomal CQ at tumor tissues and endosomal compartments.

  9. Extraction and preparation of high-aroma and low-caffeine instant green teas by the novel column chromatographic extraction method with gradient elution.

    Science.gov (United States)

    Li, Qing-Rong; Wu, Min; Huang, Rui-Jie; Chen, Ya-Fei; Chen, Chan-Jian; Li, Hui; Ni, He; Li, Hai-Hang

    2017-06-01

    The lack of aroma and natural taste is a critical problem in production and consumption of instant green teas. A method to prepare instant green teas high in-natural-aroma and low-caffeine by the novel column chromatographic extraction with gradient elution is reported. This method simultaneously extracted aroma (or volatile) and non-aroma compounds from green tea. Green tea was loaded into columns with 2.0-fold of petroleum ether (PE): ethanol (8:2). After standing for 3 h until the aroma compounds dissolved, the column was sequentially eluted with 3.0-fold 40% ethanol and 3.5-fold water. The eluant was collected together and automatically separated into PE and ethanol aqueous phases. The aroma extracts was obtained by vacuum-evaporation of PE phase at 45 °C. The ethanol aqueous phase was vacuum-concentrated to aqueous and partially or fully decaffeinated with 4% or 9% charcoal at 70 °C. A regular instant green tea with epigallocatechin-3-gallate: caffeine of 3.5:1 and a low-caffeine instant green tea (less than 1% caffeine) with excellent aroma and taste were prepared, by combining the aroma and non-aroma extracts at a 1:10 ratio. This work provides a practical approach to solve the low-aroma and low-taste problems in the production of high quality instant green teas.

  10. Charge storage characteristics of hydrogenated nanocrystalline silicon film prepared by rapid thermal annealing

    Institute of Scientific and Technical Information of China (English)

    Li Zhi-Gang; Long Shi-Bing; Liu Ming; Wang Cong-Shun; Jia Rui; Lv Jin; Shi Yi

    2007-01-01

    The early stages of hydrogenated nanocrystalline silicon (nc-Si:H) films deposited by plasma-enhanced chemical vapour deposition were characterized by atomic force microscopy.To increase the density of nanocrystals in the nc-Si:H films,the films were annealed by rapid thermal annealing (RTA) at different temperatures and then analysed by Raman spectroscopy.It Was found that the recrystallization process of the film Was optimal at around 1000℃.The effects of different RTA conditions on charge storage were characterized by capacitance-voltage measurement.Experimental results show that nc-Si:H films obtained by RTA have good charge storage characteristics for nonvolatile memory.

  11. Preparation and Evaluation of Oxaliplatin Thermosensitive Liposomes with Rapid Release and High Stability.

    Directory of Open Access Journals (Sweden)

    Chunying Zeng

    Full Text Available Oxaliplatin (OXP was reported to show low anti-tumor activity when used alone and to display side effects; this low activity was attributed to high partitioning to erythrocytes and low accumulation in tumors. Thermosensitive liposomes (TSL were considered able to specifically deliver drugs to heated tumors and to resolve the OXP distribution problem. Regretfully, TSL encapsulating doxorubicin did not demonstrate significant improvement in progression-free survival. Drug release below 41°C and significant leakage were considered major reasons for the failure. The purpose of this study was to acquire OXP TSL with rapid release at the triggered temperature and high stability at body temperature and at storage temperatures. A small quantity of poloxamer 188 was introduced into the TSL formulation to stabilize the encapsulated drug. It was shown that the addition of poloxamer 188 had no influence on the TSL characteristics. More than 90% of OXP was released within 10 min at 42°C, and less than 15% was released within 60 min at temperatures below 39°C. TSL were stable at 37°C for 96 h and at 4°C for 6 months. The anti-tumor activity of TSL at the dose of 2.5 mg/kg was certified to be equal to those of OXP injection and non-thermosensitive liposomes (NTSL at the dose of 5 mg/kg, and significant improvement of tumor inhibition was observed in TSL compared with injection and NTSL at the same dose. It was also shown from the histological transmutation of tumors that TSL had stronger anti-tumor activity. Therefore, it could be concluded that TSL composed of a proper amount of poloxamer had rapid release and high stability, and OXP TSL would be anticipated to exert prominent anti-tumor activity in the clinic.

  12. Rapid cellular internalization of multifunctional star polymers prepared by atom transfer radical polymerization.

    Science.gov (United States)

    Cho, Hong Y; Gao, Haifeng; Srinivasan, Abiraman; Hong, Joanna; Bencherif, Sidi A; Siegwart, Daniel J; Paik, Hyun-Jong; Hollinger, Jeffrey O; Matyjaszewski, Krzysztof

    2010-09-13

    Poly(ethylene glycol) (PEG) star polymers containing GRGDS (Gly-Arg-Gly-Asp-Ser) peptide sequences on the star periphery were synthesized by atom transfer radical polymerization (ATRP) of poly(ethylene glycol) methyl ether methacrylate (PEGMA), GRGDS modified poly(ethylene glycol) acrylate (GRGDS-PEG-Acryl), fluorescein o-methacrylate (FMA), and ethylene glycol dimethacrylate (EGDMA) via an "arm-first" method. Star polymers were approximately 20 nm in diameter, as measured by dynamic light scattering and atomic force microscopy. Conjugation of FMA to the stars was confirmed by fluorescence microscopy, and successful attachment of GRGDS segments to the star periphery was confirmed by (1)H NMR spectroscopy. Both fluorescent PEG star polymers with and without peripheral GRGDS peptide segments were cultured with MC3T3-E1.4 cells. These star polymers were biocompatible with ≥ 90% cell viability after 24 h of incubation. Cellular uptake of PEG star polymers in MC3T3-E1.4 cells was observed by confocal microscopy. Rapid uptake of PEG star polymers with GRGDS peptides (∼ 100% of FITC-positive cells in 15 min measured by flow cytometry) was observed, suggesting enhanced delivery potential of these functional star polymers.

  13. Analysis of niflumic acid prepared by rapid microwave-assisted evaporation.

    Science.gov (United States)

    Radacsi, Norbert; Stefanidis, Georgios D; Szabó-Révész, Piroska; Ambrus, Rita

    2014-09-01

    Evaporative crystallization is widely applied in several industrial processes, including the pharmaceutical industry. Microwave irradiation can significantly speed up solvent evaporation in these crystallization processes, resulting in reduced particle size due to rapid crystallization. A single-mode microwave setup was used for evaporative crystallization of the model active pharmaceutical ingredient, niflumic acid, and the polymer, polyvinylpirrolidone (PVP). Production of crystals by microwave irradiation offers a modern way for drug formulation, and by reducing the particle size the dissolution rate and bioavailability of the active pharmaceutical ingredient can be enhanced. In this study, a 2.5-fold increase in the dissolution rate of the produced niflumic acid crystals was observed compared to the dissolution rate of the original drug in 120min. When niflumic acid was produced together with the PVP in the microwave system, an amorphous solid dispersion was created with particles in the nano-size range, which showed a 5-fold increase in dissolution rate in 120min compared to the dissolution of the crystalline niflumic acid samples created by the microwave irradiation in the absence of PVP.

  14. Rapid preparation of ultrafine BaSO{sub 3} by SO{sub 2} storage material

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Fei; Sha, Feng; Qiao, Xian Shu; Zhao, Tian Xiang; Guo, Bo; Zhang, Jian Bin [College of Chemical Engineering, Inner Mongolia University of Technology, Huhhot (Korea, Republic of)

    2017-01-15

    In this work, a green and efficient process was developed for the preparation of ultrafine BaSO{sub 3} with layered nanostructure surface via the reaction of BaCl{sub 2} with a SO{sub 2} storage material (SO{sub 2}SM) at room temperature. The absorption of SO{sub 2} with equimolar ethylenediamine (EDA) and ethylene glycol (EG) afforded SO{sub 2}SM, which not only offered alkyl sulfite but also released EDA and EG that served as efficient surfactants to promote the formation of BaSO{sub 3} with spherical morphology and porous structure in the process of synthesis of ultrafine BaSO{sub 3}. The factors affecting the morphology and size of BaSO{sub 3} particle were assessed by investigating the effects of SO{sub 2}SM concentration, BaCl{sub 2} concentration, stirring time and speed. It was found that a higher SO{sub 2}SM concentration led to a higher degree of supersaturation, and the particle size of BaSO{sub 3} could be reduced by increasing SO{sub 2}SM concentration. Moreover, under the identified optimal reaction conditions, ultrafine BaSO{sub 3} was obtained with an average diameter of 450 nm. In addition, a plausible formation process of BaSO{sub 3} was proposed to explain the observed reaction results. Overall, the developed process in this work provides an efficient method for the capture, utilization, and conversion of SO{sub 2} into a valuable chemical.

  15. P-doped TiO2 with superior visible-light activity prepared by rapid microwave hydrothermal method

    Science.gov (United States)

    Niu, Jinfen; Lu, Pan; Kang, Mei; Deng, Kunfa; Yao, Binghua; Yu, Xiaojiao; Zhang, Qian

    2014-11-01

    Phosphorous-doped anatase TiO2 powders (P-TiO2) were prepared by rapid microwave hydrothermal method. The resulting materials were characterized by XRD, SEM, XPS, DRS and N2 adsorption. P-doping decreased the band gap and enlarged the surface area of P-doped samples than that of undoped TiO2 samples. Therefore, the photocatalytic degradation of methyl blue (MB) and tetracycline hydrochloride (Tc) experiments showed that the P-TiO2 catalysts, especially the two-steps-controlling products P-TiO2-2, exhibited higher degradation efficiency than the undoped TiO2 and commercial P25 under visible-light irradiation. Hydroxyl radicals (rad OH) have been confirmed to be the active species during the photocatalytic oxidation reaction. The microwave hydrothermal method confirms to be very suitable for the synthesis of superior visible-light activity P-doped samples.

  16. Preparation of molecularly imprinted polymer with double templates for rapid simultaneous determination of melamine and dicyandiamide in dairy products.

    Science.gov (United States)

    Liu, Jiang; Song, Han; Liu, Jie; Liu, Yuan; Li, Le; Tang, Hui; Li, Yingchun

    2015-03-01

    In this study, a rapid and accurate determination strategy was established for simultaneous measurement of melamine (MLM) and dicyandiamide (DCD) directly in powdered milk by coupling molecularly imprinted solid-phase extraction (MISPE) with high performance liquid chromatography (HPLC). A novel double-template technique was adopted for preparing SPE packing agent and the obtained double-templated (MLM and DCD) molecularly imprinted polymers (MD-MIPs) was characterized by Fourier-transform infrared spectroscopy and scanning electron microscope (SEM). The molecular recognition ability and the binding capability of the as-prepared polymers towards MLM and DCD were evaluated via static and dynamic binding tests, and it was found that the MD-MIPs showed better affinity and selectivity for both templates compared with single-templated MIPs and non-imprinted polymers (NIPs). An approach based on MISPE and HPLC was then developed and optimized to detect MLM and DCD in powdered milk. The detection limit of the method (S/N=3) were 0.13 μg/g for MLM and 0.07 μg/g for DCD, and the relative standard deviation (RSD) of intra-day and inter-day determination for MLM was 3.3% and 4.7%, and 3.5% and 5.9% for DCD. The recoveries in MLM and DCD analysis at three spiked levels were 93.1-100.1% and 75.7-82.5%, respectively, with all RSD less than 5.2%.

  17. Rapid screening and analysis of alpha- and gamma-emitting radionuclides in liquids using a single sample preparation procedure.

    Science.gov (United States)

    Parsa, Bahman; Henitz, James B; Carter, Jennifer A

    2011-02-01

    A multifaceted radiochemical testing procedure has been developed to analyze a large number of liquid samples and measure a wide range of radionuclides in a short period of time. This method involves a single, unique and fast sample preparation procedure and allows sequential/concurrent determination of analytes with accuracy and precision. The same prepared sample can be selectively analyzed by gross alpha counting, gamma-ray spectroscopy, and alpha spectroscopy. This method is especially attractive in radiological emergency events where analytical data will be needed urgently as a basis for protective action. Given the simplicity and rapidity of the method, it may be suitable for field portable laboratories, which could save time and the cost associated with the transit of samples to a fixed laboratory. A 100 mL aliquot of sample was spiked with ¹³³Ba and ⁵⁹Fe tracers and subjected to a chemical separation procedure using a combined BaSO4 and Fe(OH)3 co-precipitation scheme. Then, the gross alpha-particle activity of the prepared sample was measured with a low-background gas-proportional counter, followed by the analysis of its photon-emitters using a gamma-ray spectroscopy system with high-purity intrinsic Ge detectors. Gamma-ray determination of ¹³³Ba and ⁵⁹Fe tracers was used to assess the chemical recoveries of BaSO4 and Fe(OH)3 fractions, respectively. Selectivity of the radionuclides for co-precipitation with either BaSO4 or Fe(OH)3 components was also investigated. Alpha mass-efficiency curves were derived using ²³⁰Th and ²⁴¹Am standards as alpha-calibration sources. Various mixtures of radionuclides, including ⁵⁴Mn, ⁵⁷Co, ⁶⁰Co, ⁸⁵Sr, ⁸⁸Y, ¹⁰⁹Cd, ¹¹³Sn, ¹³⁷Cs, ¹³⁹Ce, ²⁰³Hg, ²⁰⁹Po, ²²⁶Ra, ²²⁸Ra, ²³⁰Th, ²⁴¹Am, and natural uranium were used in this study. Most were quantitatively assayed with high chemical recoveries. Alpha-isotope identification and assessment of the prepared

  18. High energy X-ray diffraction study of a dental ceramics–titanium functional gradient material prepared by field assisted sintering technique

    Energy Technology Data Exchange (ETDEWEB)

    Witte, K., E-mail: kerstin.witte@uni-rostock.de [Institute of Physics, University of Rostock, August-Bebel-Str. 55, 18055 Rostock (Germany); Bodnar, W. [Institute of Physics, University of Rostock, August-Bebel-Str. 55, 18055 Rostock (Germany); Schell, N. [Institute of Materials Research, Helmholtz-Center Geesthacht, Max-Planck-Str. 1, 21502 Geesthacht (Germany); Lang, H. [Department of Operative Dentistry and Periodontology, University of Rostock, Strempelstr. 13, 18057 Rostock (Germany); Burkel, E. [Institute of Physics, University of Rostock, August-Bebel-Str. 55, 18055 Rostock (Germany)

    2014-09-15

    A functional gradient material with eleven layers composed of a dental ceramics and titanium was successfully consolidated using field assisted sintering technique in a two-step sintering process. High energy X-ray diffraction studies on the gradient were performed at High Energy Material Science beamline at Desy in Hamburg. Phase composition, crystal unit edges and lattice mismatch along the gradient were determined applying Rietveld refinement procedure. Phase analysis revealed that the main crystalline phase present in the gradient is α-Ti. Crystallinity increases stepwisely along the gradient with a decreasing increment between every next layer, following rather the weight fraction of titanium. The crystal unit edge a of titanium remains approximately constant with a value of 2.9686(1) Å, while c is reduced with increasing amount of titanium. In the layer with pure titanium the crystal unit edge c is constant with a value of 4.7174(2) Å. The lattice mismatch leading to an internal stress was calculated over the whole gradient. It was found that the maximal internal stress in titanium embedded in the studied gradient is significantly smaller than its yield strength, which implies that the structure of titanium along the whole gradient is mechanically stable. - Highlights: • High energy XRD studies of dental ceramics–Ti gradient material consolidated by FAST. • Phase composition, crystallinity and lattice parameters are determined. • Crystallinity increases stepwisely along the gradient following weight fraction of Ti. • Lattice mismatch leading to internal stress is calculated over the whole gradient. • Internal stress in α-Ti embedded in the gradient is smaller than its yield strength.

  19. Preparation

    Directory of Open Access Journals (Sweden)

    M.M. Dardir

    2014-03-01

    Full Text Available Some hexanamide-mono and di-linoleniate esters were prepared by the reaction of linolenic acid and hexanamide (derived from the reaction of hexanoic acid and diethanolamine. The chemical structure for the newly prepared hexanamide-mono and di-linoleniate esters were elucidated using elemental analysis, (FTIR, H 1NMR and chemical ionization mass spectra (CI/Ms spectroscopic techniques. The results of the spectroscopic analysis indicated that they were prepared through the right method and they have high purity. The new prepared esters have high biodegradability and lower toxicity (environmentally friendly so they were evaluated as a synthetic-based mud (ester-based mud for oil-well drilling fluids. The evaluation included study of the rheological properties, filtration and thermal properties of the ester based-muds formulated with the newly prepared esters compared to the reference commercial synthetic-based mud.

  20. Microstructure, corrosion behavior and cytotoxicity of biodegradable Mg–Sn implant alloys prepared by sub-rapid solidification

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Chaoyong [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); Pan, Fusheng, E-mail: fspan@cqu.edu.cn [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Chongqing Academy of Science and Technology, Chongqing 401123 (China); Zhao, Shuang; Pan, Hucheng; Song, Kai [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); Tang, Aitao [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China)

    2015-09-01

    In this study, biodegradable Mg–Sn alloys were fabricated by sub-rapid solidification, and their microstructure, corrosion behavior and cytotoxicity were investigated by using optical microscopy, scanning electron microscopy equipped with an energy dispersive X-ray spectroscopy, X-ray diffraction, immersion test, potentiodynamic polarization test and cytotoxicity test. The results showed that the microstructure of Mg–1Sn alloy was almost equiaxed grain, while the Mg–Sn alloys with higher Sn content (Sn ≥ 3 wt.%) displayed α-Mg dendrites, and the secondary dendrite arm spacing of the primary α-Mg decreased significantly with increasing Sn content. The Mg–Sn alloys consisted of primary α-Mg matrix, Sn-rich segregation and Mg{sub 2}Sn phase, and the amount of Mg{sub 2}Sn phases increased with increasing Sn content. Potentiodynamic polarization and immersion tests revealed that the corrosion rates of Mg–Sn alloys increased with increasing Sn content. Cytotoxicity test showed that Mg–1Sn and Mg–3Sn alloys were harmless to MG63 cells. These results of the present study indicated that Mg–1Sn and Mg–3Sn alloys were promising to be used as biodegradable implants. - Highlights: • Biodegradable Mg–Sn implant alloys were prepared by sub-rapid solidification. • Secondary dendrite arm spacing of alloys decreased with increasing Sn content. • Corrosion rates of alloys increased significantly with increasing Sn content. • Mg–1Sn and Mg–3Sn alloys were harmless to MG63 cells.

  1. Preparing for and Executing a Randomised Controlled Trial of Podoconiosis Treatment in Northern Ethiopia: The Utility of Rapid Ethical Assessment.

    Directory of Open Access Journals (Sweden)

    Henok Negussie

    2016-03-01

    Full Text Available Community-based randomized controlled trials are often complex pieces of research with significant challenges around the approach to the community, information provision, and decision-making, all of which are fundamental to the informed consent process. We conducted a rapid ethical assessment to guide the preparation for and conduct of a randomized controlled trial of podoconiosis treatment in northern Ethiopia.A qualitative study was carried out in Aneded woreda, East Gojjam Zone, Amhara Regional State from August to September, 2013. A total of 14 In-depth Interviews (IDIs with researchers, experts, and leaders, and 8 Focus Group Discussions (FGDs involving 80 participants (people of both gender, with and without podoconiosis, were conducted. Interviews were carried out in Amharic. Data analysis was started alongside collection. Final data analysis used a thematic approach based on themes identified a priori and those that emerged during the analysis.Respondents made a range of specific suggestions, including that sensitisation meetings were called by woreda or kebele leaders or the police; that Health Extension Workers were asked to accompany the research team to patients' houses; that detailed trial information was explained by someone with deep local knowledge; that analogies from agriculture and local social organisations be used to explain randomisation; that participants in the 'delayed' intervention arm be given small incentives to continue in the trial; and that key community members be asked to quell rumours arising in the course of the trial.Many of these recommendations were incorporated into the preparatory phases of the trial, or were used during the course of the trial itself. This demonstrates the utility of rapid ethical assessment preceding a complex piece of research in a relatively research-naive setting.

  2. Desorption electrospray ionisation mass spectrometry: A rapid screening tool for veterinary drug preparations and forensic samples from hormone crime investigations

    Energy Technology Data Exchange (ETDEWEB)

    Nielen, M.W.F. [RIKILT Institute of Food Safety, P.O. Box 230, 6700 AE Wageningen (Netherlands); Wageningen University, Laboratory of Organic Chemistry, Dreijenplein 8, 6703 HB Wageningen (Netherlands)], E-mail: michel.nielen@wur.nl; Hooijerink, H. [RIKILT Institute of Food Safety, P.O. Box 230, 6700 AE Wageningen (Netherlands); Claassen, F.C. [Wageningen University, Laboratory of Organic Chemistry, Dreijenplein 8, 6703 HB Wageningen (Netherlands); Engelen, M.C. van [RIKILT Institute of Food Safety, P.O. Box 230, 6700 AE Wageningen (Netherlands); Beek, T.A. van [Wageningen University, Laboratory of Organic Chemistry, Dreijenplein 8, 6703 HB Wageningen (Netherlands)

    2009-04-01

    Hormone and veterinary drug screening and forensics can benefit from the recent developments in desorption electrospray ionisation (DESI) mass spectrometry (MS). In this work the feasibility of DESI application has been studied. Using a linear ion trap or quadrupole time-of-flight (TOF) MS instrument both full-scan and data-dependent collision-induced dissociation MS{sup n} spectra were acquired in seconds without sample preparation. Preliminary data are presented for the rapid screening of (pro)hormone supplement samples, an illegal steroid cocktail and forensic samples from veterinary drug investigations. The potential of this DESI approach is clearly demonstrated since compounds observed could be independently confirmed by liquid chromatography/TOFMS with accurate mass measurement, and/or proton nuclear magnetic resonance spectroscopy. Specific concerns related to false-positive and false-negative findings due to limitations in quantification and memory-effects are briefly discussed. It is envisaged that DESI will achieve a prominent role in hormone and veterinary drug analysis in the near future.

  3. Amorphization and thermal stability of aluminum-based nanoparticles prepared from the rapid cooling of nanodroplets: effect of iron addition.

    Science.gov (United States)

    Xiao, Shifang; Li, Xiaofan; Deng, Huiqiu; Deng, Lei; Hu, Wangyu

    2015-03-07

    Despite an intensive investigation on bimetallic nanoparticles, little attention has been paid to their amorphization in the past few decades. The study of amorphization on a nanoscale is of considerable significance for the preparation of amorphous nanoparticles and bulk metallic glass. Herein, we pursue the amorphization process of Al-based nanoparticles with classic molecular dynamics simulations and local structural analysis techniques. By a comparative study of the amorphization of pure Al and Fe-doped Al-based nanodroplets in the course of rapid cooling, we find that Fe addition plays a very important role in the vitrification of Al-based nanodroplets. Owing to the subsurface segregated Fe atoms with their nearest neighbors tending to form relatively stable icosahedral (ICO) clusters, the Fe-centred cluster network near the surface effectively suppresses the crystallization of droplets from surface nucleation and growth as the concentration of Fe attains a certain value. The glass formation ability of nanodroplets is suggested to be enhanced by the high intrinsic inner pressure as a result of small size and surface tension, combined with the dopant-inhibited surface nucleation. In addition, the effect of the size and the added concentration of nanoparticles on amorphization and the thermal stability of the amorphous nanoparticles are discussed. Our findings reveal the amorphization mechanism in Fe-doped Al-based nanoparticles and provide a theoretical guidance for the design of amorphous materials.

  4. A lab-on-a-chip system with integrated sample preparation and loop-mediated isothermal amplification for rapid and quantitative detection of Salmonella spp. in food samples

    DEFF Research Database (Denmark)

    Sun, Yi; Than Linh, Quyen; Hung, Tran Quang

    2015-01-01

    and usually take a few hours to days to complete. In response to the demand for rapid on line or at site detection of pathogens, in this study, we describe for the first time an eight-chamber lab-on-a-chip (LOC) system with integrated magnetic beads-based sample preparation and loop-mediated isothermal...

  5. Gradient networks

    Science.gov (United States)

    Toroczkai, Zoltán; Kozma, Balázs; Bassler, Kevin E.; Hengartner, N. W.; Korniss, G.

    2008-04-01

    Gradient networks are defined (Toroczkai and Bassler 2004 Nature 428 716) as directed graphs formed by local gradients of a scalar field distributed on the nodes of a substrate network G. We present the derivation for some of the general properties of gradient graphs and give an exact expression for the in-degree distribution R(l) of the gradient network when the substrate is a binomial (Erd{\\;\\kern -0.10em \\raise -0.35ex \\{{^{^{\\prime\\prime}}}}\\kern -0.57em \\o} s-Rényi) random graph, G_{N,p} , and the scalars are independent identically distributed (i.i.d.) random variables. We show that in the limit N \\to \\infty, p \\to 0, z = pN = \\mbox{const} \\gg 1, R(l)\\propto l^{-1} for l Bassler (2004 Nature 428 716).

  6. Rapid Registration Algorithm of Large-Scale Images Based on Normalized Gradient Phase Correlation%基于归一化梯度相位相关的大尺度图像快速配准算法

    Institute of Scientific and Technical Information of China (English)

    陈怀玉; 杨旸

    2015-01-01

    To solve the real﹣time registration problem of large﹣scale images with rotations, scalings, translations simultaneously, an image registration algorithm based on normalized gradient phase correlation is proposed in this paper. The complicated multilayer computation, interpolation and iteration is avoided in this algorithm. Plural gradient images are disposed by normalized gradient phase correlation. Giving consideration to robustness and rapidity of parameters estimation at the same time, this algorithm can efficiently expand the estimation range of transformation parameters. By means of parameter﹣adjustable window function, it can suppress the influence of the edge effect of the different kinds of images. Experimental results illustrate the rapidity and effectiveness of the proposed algorithm.%针对具有旋转、缩放、平移的大尺度变换图像的实时配准问题,提出基于归一化梯度相位相关的图像配准算法。该算法避免复杂的多层插值计算和迭代处理过程,利用归一化梯度相位相关法处理复数梯度图像,能在兼顾参数估计的鲁棒性和快速性的同时,扩大图像变换参数的估计范围。并通过一种参数可调整的窗函数有效抑制不同种类图像的边缘效应的影响。实验证明该算法的快速性和有效性。

  7. How prepared are UK medical graduates for practice? A rapid review of the literature 2009–2014

    Science.gov (United States)

    Grundy, Lisa; Mann, Mala; John, Zoe; Panagoulas, Eleni; Bullock, Alison; Mattick, Karen

    2017-01-01

    Objective To understand how prepared UK medical graduates are for practice and the effectiveness of workplace transition interventions. Design A rapid review of the literature (registration #CRD42013005305). Data sources Nine major databases (and key websites) were searched in two timeframes (July–September 2013; updated May–June 2014): CINAHL, Embase, Educational Resources Information Centre, Health Management Information Consortium, MEDLINE, MEDLINE in Process, PsycINFO, Scopus and Web of Knowledge. Eligibility criteria for selecting studies Primary research or studies reporting UK medical graduates' preparedness between 2009 and 2014: manuscripts in English; all study types; participants who are final-year medical students, medical graduates, clinical educators, patients or NHS employers and all outcome measures. Data extraction At time 1, three researchers screened manuscripts (for duplicates, exclusion/inclusion criteria and quality). Remaining 81 manuscripts were coded. At time 2, one researcher repeated the process for 2013–2014 (adding six manuscripts). Data were analysed using a narrative synthesis and mapped against Tomorrow's Doctors (2009) graduate outcomes. Results Most studies comprised junior doctors' self-reports (65/87, 75%), few defined preparedness and a programmatic approach was lacking. Six themes were highlighted: individual skills/knowledge, interactional competence, systemic/technological competence, personal preparedness, demographic factors and transitional interventions. Graduates appear prepared for history taking, physical examinations and some clinical skills, but unprepared for other aspects, including prescribing, clinical reasoning/diagnoses, emergency management, multidisciplinary team-working, handover, error/safety incidents, understanding ethical/legal issues and ward environment familiarity. Shadowing and induction smooth transition into practice, but there is a paucity of evidence around assistantship efficacy

  8. How prepared are UK medical graduates for practice? A rapid review of the literature 2009-2014.

    Science.gov (United States)

    Monrouxe, Lynn V; Grundy, Lisa; Mann, Mala; John, Zoe; Panagoulas, Eleni; Bullock, Alison; Mattick, Karen

    2017-01-13

    To understand how prepared UK medical graduates are for practice and the effectiveness of workplace transition interventions. A rapid review of the literature (registration #CRD42013005305). Nine major databases (and key websites) were searched in two timeframes (July-September 2013; updated May-June 2014): CINAHL, Embase, Educational Resources Information Centre, Health Management Information Consortium, MEDLINE, MEDLINE in Process, PsycINFO, Scopus and Web of Knowledge. Primary research or studies reporting UK medical graduates' preparedness between 2009 and 2014: manuscripts in English; all study types; participants who are final-year medical students, medical graduates, clinical educators, patients or NHS employers and all outcome measures. At time 1, three researchers screened manuscripts (for duplicates, exclusion/inclusion criteria and quality). Remaining 81 manuscripts were coded. At time 2, one researcher repeated the process for 2013-2014 (adding six manuscripts). Data were analysed using a narrative synthesis and mapped against Tomorrow's Doctors (2009) graduate outcomes. Most studies comprised junior doctors' self-reports (65/87, 75%), few defined preparedness and a programmatic approach was lacking. Six themes were highlighted: individual skills/knowledge, interactional competence, systemic/technological competence, personal preparedness, demographic factors and transitional interventions. Graduates appear prepared for history taking, physical examinations and some clinical skills, but unprepared for other aspects, including prescribing, clinical reasoning/diagnoses, emergency management, multidisciplinary team-working, handover, error/safety incidents, understanding ethical/legal issues and ward environment familiarity. Shadowing and induction smooth transition into practice, but there is a paucity of evidence around assistantship efficacy. Educational interventions are needed to address areas of unpreparedness (eg, multidisciplinary team

  9. Dung beetle community and functions along a habitat-disturbance gradient in the Amazon: a rapid assessment of ecological functions associated to biodiversity.

    Science.gov (United States)

    Braga, Rodrigo F; Korasaki, Vanesca; Andresen, Ellen; Louzada, Julio

    2013-01-01

    Although there is increasing interest in the effects of habitat disturbance on community attributes and the potential consequences for ecosystem functioning, objective approaches linking biodiversity loss to functional loss are uncommon. The objectives of this study were to implement simultaneous assessment of community attributes (richness, abundance and biomass, each calculated for total-beetle assemblages as well as small- and large-beetle assemblages) and three ecological functions of dung beetles (dung removal, soil perturbation and secondary seed dispersal), to compare the effects of habitat disturbance on both sets of response variables, and their relations. We studied dung beetle community attributes and functions in five land-use systems representing a disturbance gradient in the Brazilian Amazon: primary forest, secondary forest, agroforestry, agriculture and pasture. All response variables were affected negatively by the intensification of habitat disturbance regimes, but community attributes and ecological functions did not follow the same pattern of decline. A hierarchical partitioning analysis showed that, although all community attributes had a significant effect on the three ecological functions (except the abundance of small beetles on all three ecological functions and the biomass of small beetles on secondary dispersal of large seed mimics), species richness and abundance of large beetles were the community attributes with the highest explanatory value. Our results show the importance of measuring ecological function empirically instead of deducing it from community metrics.

  10. Dung beetle community and functions along a habitat-disturbance gradient in the Amazon: a rapid assessment of ecological functions associated to biodiversity.

    Directory of Open Access Journals (Sweden)

    Rodrigo F Braga

    Full Text Available Although there is increasing interest in the effects of habitat disturbance on community attributes and the potential consequences for ecosystem functioning, objective approaches linking biodiversity loss to functional loss are uncommon. The objectives of this study were to implement simultaneous assessment of community attributes (richness, abundance and biomass, each calculated for total-beetle assemblages as well as small- and large-beetle assemblages and three ecological functions of dung beetles (dung removal, soil perturbation and secondary seed dispersal, to compare the effects of habitat disturbance on both sets of response variables, and their relations. We studied dung beetle community attributes and functions in five land-use systems representing a disturbance gradient in the Brazilian Amazon: primary forest, secondary forest, agroforestry, agriculture and pasture. All response variables were affected negatively by the intensification of habitat disturbance regimes, but community attributes and ecological functions did not follow the same pattern of decline. A hierarchical partitioning analysis showed that, although all community attributes had a significant effect on the three ecological functions (except the abundance of small beetles on all three ecological functions and the biomass of small beetles on secondary dispersal of large seed mimics, species richness and abundance of large beetles were the community attributes with the highest explanatory value. Our results show the importance of measuring ecological function empirically instead of deducing it from community metrics.

  11. 一种利用梯度光掩模制备梯度表面的简便方法%A FACILE METHOD FOR PREPARING POLYMER GRADIENT SURFACES WITH A PRINTED GRADATION PHOTOMASK

    Institute of Scientific and Technical Information of China (English)

    汪炉林; 马育红; 周昊; 杨万泰

    2011-01-01

    A novel and facile method using a printed gradation photomask combined with photoreactions for preparing polymer surfaces with gradient distribution of surface energy, grafting layer thickness and grafting chain density was developed. The gradation photomask with gradient change of photo transmittance intensity,almost in the range of 0 ~ 100% at both 254 nm and 365 nm, has been successfully prepared by direct printing black ink onto the biaxially oriented polypropylene and silica (BOPP/SiOx) hybrid film. The applications of the gradient photomask in photo-induced reactions, such as confined photo-catalytic oxidation (CPO) and photografting polymerizations, have been exploited. In CPO reaction with a printed gradient photomask, the static water contact angles (CAs) of modified surfaces of BOPP and PET films exhibited the surface energy gradient properties, for example, the CAs of BOPP decreased almost linearly from about 103° (unmodified) to about 39° and PET film from about 78° (unmodified) to less than 10° respectively. In UV induced surface grafting polymerization of scrylic acid (AA), the dry thickness of PAA brushes showed a gradient change from about several nanometers to bout 750 nm on the BOPP film substrate. While in precipitation-photografting polymerization of acrylamide ( AM), ATR-FTIR, X-ray photoelectron spectroscopy ( XPS), fluorescence microscopy and scanning electron microscopy (SEM) demonstrated the existence of the gradient grafting chain density on the polymer surfaces, i. e, the content of Nitrogen determined by XPS increased from about 0 wt% of pristine BOPP film to about 11.28%. So far, this is one of the most convenient methods reported for preparation of polymer gradient surfaces, and it is a versatile facile method in preparation of a gradient surface controlled by the gradation photomask.%以自制杂化双向拉伸聚丙烯/氧化硅(BOPP/SiOx)有机/无机杂化膜为基材,由喷墨打印机直接在杂化膜表面打印色

  12. A rapid HPLC column switching method for sample preparation and determination of β-carotene in food supplements.

    Science.gov (United States)

    Brabcová, Ivana; Hlaváčková, Markéta; Satínský, Dalibor; Solich, Petr

    2013-11-15

    A simple and automated HPLC column-switching method with rapid sample pretreatment has been developed for quantitative determination of β-carotene in food supplements. Commercially samples of food supplements were dissolved in chloroform with help of saponification with 1M solution of sodium hydroxide in ultrasound bath. A 20-min sample dissolution/extraction step was necessary before chromatography analysis to transfer β-carotene from solid state of food supplements preparations (capsules,tablets) to chloroform solution. Sample volume - 3μL of chloroform phase was directly injected into the HPLC system. Next on-line sample clean-up was achieved on the pretreatment precolumn Chromolith Guard Cartridge RP-18e (Merck), 10×4.6mm, with a washing mobile phase (methanol:water, 92:8, (v/v)) at a flow rate of 1.5mL/min. Valve switch to analytical column was set at 2.5min in a back-flush mode. After column switching to the analytical column Ascentis Express C-18, 30×4.6mm, particle size 2.7μm (Sigma Aldrich), the separation and determination of β-carotene in food supplements was performed using a mobile phase consisting of 100% methanol, column temperature at 60°C and flow rate 1.5mL/min. The detector was set at 450nm. Under the optimum chromatographic conditions standard calibration curve was measured with good linearity - correlation coefficient for β-carotene (r(2)=0.999014; n=6) between the peak areas and concentration of β-carotene 20-200μg/mL. Accuracy of the method defined as a mean recovery was in the range 96.66-102.40%. The intraday method precision was satisfactory at three concentration levels 20, 125 and 200μg/mL and relative standard deviations were in the range 0.90-1.02%. The chromatography method has shown high sample throughput during column-switching pretreatment process and analysis in one step in short time (6min) of the whole chromatographic analysis.

  13. State-of-the-art technologies for rapid and high-throughput sample preparation and analysis of N-glycans from antibodies.

    Science.gov (United States)

    Aich, Udayanath; Lakbub, Jude; Liu, Aston

    2016-06-01

    Glycosylation is a PTM that occurs during production of many protein-based biologic drugs and can have a profound impact on their biological, clinical, and pharmacological properties. Quality by design, process optimization, and advance in manufacturing technology create a demand for robust, sensitive, and accurate profiling and quantification of antibody glycosylation. Potential drawbacks in antibody glycosylation profiling include the high hands-on time required for sample preparation and several hours for data acquisition and analysis. Rapid and high-throughput (HTP) N-glycan profiling and characterization along with automation for sample preparation and analysis are essential for extensive antibody glycosylation analysis due to the substantial improvement of turnaround time. The first part of this review article will focus on the recent progress in rapid and HTP sample preparation and analysis of antibody glycosylation. Subsequently, the article will cover a brief overview of various separation and mass spectrometric methods for the rapid and HTP analysis of N-glycans in antibodies. Finally, we will discuss the recent developments in process analytical technologies for the screening and quantification of N-glycans in antibodies.

  14. Thermoelectric performance of CuFeS2+2x composites prepared by rapid thermal explosion

    National Research Council Canada - National Science Library

    Hongyao Xie; Xianli Su; Yonggao Yan; Wei Liu; Liangjun Chen; Jiefei Fu; Jihui Yang; Ctirad Uher; Xinfeng Tang

    2017-01-01

    .... All these factors limit commercial applications of the thermoelectric materials. Therefore, it is imperative to develop efficient, inexpensive and non-toxic materials and explore rapid and low-cost synthesis methods...

  15. Combustion Synthesis of TiB2-TiC/42CrMo4 Composites with Gradient Joint Prepared in Different High-Gravity Fields

    Science.gov (United States)

    Huang, Xuegang; Huang, Jie; Zhao, Zhongmin; Yin, Chun; Zhang, Long; Wu, Junyan

    2015-12-01

    The novel TiB2-TiC/42CrMo4-laminated composite materials were successfully fabricated by combustion synthesis in different high-gravity fields. This ceramic/metal composite material possesses continuously graded composition, and multilevel gradient microstructure, which is composed of TiB2-TiC ceramic substrate, ceramic-based intermediate layer, metal-based intermediate layer, and 42CrMo4 substrate. The ceramic-based intermediate layer is the main gradient transition region in the joint which shows that the TiB2 and TiC grains decrease gradually in size and volume fraction from the ceramic substrate to metal substrate. The experiment reveals that the increased high-gravity field not only leads to the higher combustion temperature and the remarkable thermal explosion mode, but also attributes to the enhanced interdiffusion and convection between the molten steel surface and liquid TiB2-based ceramic. So, the reliable fusion bonding of TiB2-TiC/42CrMo4 composite materials is achieved. Moreover, the phase separation and forced filling effect of high-gravity field is the key to improve the densification and bond performance of the joint. The ceramic/metal joint in the continuous gradient composition and microstructure represents not only the transitional change of Vickers hardness, but also the high shear bond strength of 420 ± 25 MPa.

  16. Rapid Biochemical Analysis on the International Space Station (ISS): Preparing for Human Exploration of the Moon and Mars

    Science.gov (United States)

    Maule, J.; Morris, Heather; Monaco, L.; Steele, A.; Wainwright, N.

    2008-01-01

    The Lab-on-a-Chip Application Development - Portable Test System, known as LOCAD-PTS, was launched to the International Space Station (ISS) aboard Space Shuttle Discovery (STS-116) on December 9th,2006. Since that time, it has remained onboard ISS and has been operated by the crew on 10 separate occasions LOCAD-PTS is a handheld device for rapid biochemical analysis; it consists of a spectrophotometer, a series of interchangeable cartridges, a pipette and several clean/sterilized swabbing kits to obtain samples from ISS surfaces. Sampling, quantitative analysis and data retrieval is performed onboard, therefore reducing the need to return samples to Earth. Less than 20 minutes are required from sampling to data, significantly faster than existing culture-based methods on ISS, which require 3-5 days. Different cartridges are available for the detection of different target molecules (simply by changing the formulation within each cartridge), thereby maximizing the benefit and applications addressed by a single instrument. Initial tests on ISS have focused on the detection of the bact.erial macromolecule endotoxin, a component of bacterial cell walls. LOCAD-PTS detects endotoxin with a cartridge that contains a formulation known as Limulus Amebocyte Lysate (LAL) assay. LAL is derived from blood of the horseshoe crab, Limulus polyphemus, and detects enodotoxin with an enzyme cascade that triggers generation Of a yellow colored dye, p-nitroanaline. The more p-nitroanaline product, the more endotoxin is in the original sample. To enable quantitative analysis, the absorbance of this color is measured by LOCAD-PTS through a 395 nm filter and compared with an internal calibration curve, to provide a reading on the LED display that ranges from 0.05 Endotoxin Units (EU)/ml to 5 EU/ml. Several surface sites were analyzed within ISS between March 2007 and February 2008, including multiple locations in the US Laboratory Destiny, Node 1 Unity, AMock, and Service Module Zvezda

  17. Rapid Biochemical Analysis on the International Space Station (ISS): Preparing for Human Exploration of the Moon and Mars

    Science.gov (United States)

    Maule, J.; Morris, Heather; Monaco, L.; Steele, A.; Wainwright, N.

    2008-01-01

    The Lab-on-a-Chip Application Development - Portable Test System, known as LOCAD-PTS, was launched to the International Space Station (ISS) aboard Space Shuttle Discovery (STS-116) on December 9th,2006. Since that time, it has remained onboard ISS and has been operated by the crew on 10 separate occasions LOCAD-PTS is a handheld device for rapid biochemical analysis; it consists of a spectrophotometer, a series of interchangeable cartridges, a pipette and several clean/sterilized swabbing kits to obtain samples from ISS surfaces. Sampling, quantitative analysis and data retrieval is performed onboard, therefore reducing the need to return samples to Earth. Less than 20 minutes are required from sampling to data, significantly faster than existing culture-based methods on ISS, which require 3-5 days. Different cartridges are available for the detection of different target molecules (simply by changing the formulation within each cartridge), thereby maximizing the benefit and applications addressed by a single instrument. Initial tests on ISS have focused on the detection of the bact.erial macromolecule endotoxin, a component of bacterial cell walls. LOCAD-PTS detects endotoxin with a cartridge that contains a formulation known as Limulus Amebocyte Lysate (LAL) assay. LAL is derived from blood of the horseshoe crab, Limulus polyphemus, and detects enodotoxin with an enzyme cascade that triggers generation Of a yellow colored dye, p-nitroanaline. The more p-nitroanaline product, the more endotoxin is in the original sample. To enable quantitative analysis, the absorbance of this color is measured by LOCAD-PTS through a 395 nm filter and compared with an internal calibration curve, to provide a reading on the LED display that ranges from 0.05 Endotoxin Units (EU)/ml to 5 EU/ml. Several surface sites were analyzed within ISS between March 2007 and February 2008, including multiple locations in the US Laboratory Destiny, Node 1 Unity, AMock, and Service Module Zvezda

  18. Improved mass spectrometric analysis of membrane proteins based on rapid and versatile sample preparation on nanodiamond particles.

    Science.gov (United States)

    Pham, Minh D; Yu, Steve S-F; Han, Chau-Chung; Chan, Sunney I

    2013-07-16

    We have developed a novel streamlined sample preparation procedure for mass spectrometric (MS) analysis of membrane proteins using surface-oxidized nanodiamond particles. The platform consists of solid-phase extraction and elution of the membrane proteins on nanodiamonds, concentrating the membrane proteins on the nanodiamonds and separating out detergents, chaotropic agents, and salts, and other impurities that are often present at high concentrations in solubilized membrane preparations. In this manner, membrane-protein extracts are transformed into MS-ready samples in minutes. The protocol is not only fast, but also widely adaptable and highly effective for preparing generic membrane protein samples for both MALDI-MS studies of membrane-protein complexes and shotgun membrane proteomics studies. As proof of concept, we have demonstrated substantial improvements in the MALDI-MS analysis of the particulate methane monooxygenase (pMMO) complex, a three-subunit transmembrane protein solubilized in various detergent buffers. Enzymatic digestions of membrane proteins are also greatly facilitated since the proteins extracted on to the nanodiamonds are exposed on the surface of the nanoparticles rather than in SDS gels or in detergent solutions. We illustrate the effectiveness of nanodiamonds for SDS removal in the preparation of membrane proteins for MS analysis on the proteome level by examining the quality of the tryptic peptides prepared by on-surface nanodiamond digestion of an E. coli membrane fraction for shotgun proteomics.

  19. Effect of preparation and test variables on the dissolution kinetics in saline solutions of rapidly solidified and standard magnesium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, D.S. [School of Materials, Univ. of Sheffield (United Kingdom); Edyvean, R.G.J. [School of Materials, Univ. of Sheffield (United Kingdom); Jones, H. [School of Materials, Univ. of Sheffield (United Kingdom); Sellars, C.M. [School of Materials, Univ. of Sheffield (United Kingdom)

    1992-12-31

    Renewed interest in the factors that determine the corrosion characteristics of magnesium alloys has been stimulated of late by the opportunity to provide high strength, corrosion resistant magnesium alloys as ultralight castings and wrought products for automobile and aerospace applications. The present contribution forms part of continuing work at Sheffield to develop improved magnesium alloys by rapid solidification routes. It was motivated by the need to assess the usefulness of dissolution rate, measured during short-term immersion in 3% NaCl solution of rapidly solidified samples, such as splats or ribbons, as a screening parameter to select alloys for full evaluation in scale-up quantities. (orig.)

  20. Porous Ti6Al4V scaffold directly fabricating by rapid prototyping: preparation and in vitro experiment

    NARCIS (Netherlands)

    Li, Jia Ping; Wijn, de Joost R.; Blitterswijk, van Clemens A.; Groot, de Klaas

    2006-01-01

    Three-dimensional (3D) fiber deposition (3DF), a rapid prototyping technology, was successfully directly applied to produce novel 3D porous Ti6Al4V scaffolds with fully interconnected porous networks and highly controllable porosity and pore size. A key feature of this technology is the 3D computer-

  1. A rapid sonication based method for preparation of stromal vascular fraction and mesenchymal stem cells from fat tissue

    Directory of Open Access Journals (Sweden)

    Mohammad Amir Amirkhani

    2016-06-01

    Conclusion: The current protocol based on the sonication-mediated cavitation is a rapid, safe and cost-effective method, which is proposed for isolation of SVF and of course ADSCs cultures in a large scale for the clinical trials or therapeutic purposes.

  2. Mechanical properties of amorphous alloys ribbons prepared by rapid quenching of the melt after different thermal treatments before quenching

    NARCIS (Netherlands)

    Tabachnikova, ED; Bengus, VZ; Egorov, D V; Tsepelev, VS; Ocelik, Vaclav

    1997-01-01

    The mechanical properties of amorphous alloy are greatly influenced by the thermal treatment of its melt before rapid quenching. The strength and the fracture toughness of some amorphous alloys obtained after melt beating above the melt critical temperature T-CR are essentially higher than those obt

  3. Rapid Biochemical Analysis on the International Space Station (ISS): Preparing for Human Exploration of the Moon and Mars

    Science.gov (United States)

    Maule, J.; Morris, Heather; Monaco, L.; Steele, A.; Wainwright, N.

    2008-01-01

    The Lab-on-a-Chip Application Development - Portable Test System, known as LOCAD-PTS, was launched to the International Space Station (ISS) aboard Space Shuttle Discovery (STS-116) on December 9th,2006. Since that time, it has remained onboard ISS and has been operated by the crew on 10 separate occasions LOCAD-PTS is a handheld device for rapid biochemical analysis; it consists of a spectrophotometer, a series of interchangeable cartridges, a pipette and several clean/sterilized swabbing kits to obtain samples from ISS surfaces. Sampling, quantitative analysis and data retrieval is performed onboard, therefore reducing the need to return samples to Earth. Less than 20 minutes are required from sampling to data, significantly faster than existing culture-based methods on ISS, which require 3-5 days. Different cartridges are available for the detection of different target molecules (simply by changing the formulation within each cartridge), thereby maximizing the benefit and applications addressed by a single instrument. Initial tests on ISS have focused on the detection of the bact.erial macromolecule endotoxin, a component of bacterial cell walls. LOCAD-PTS detects endotoxin with a cartridge that contains a formulation known as Limulus Amebocyte Lysate (LAL) assay. LAL is derived from blood of the horseshoe crab, Limulus polyphemus, and detects enodotoxin with an enzyme cascade that triggers generation Of a yellow colored dye, p-nitroanaline. The more p-nitroanaline product, the more endotoxin is in the original sample. To enable quantitative analysis, the absorbance of this color is measured by LOCAD-PTS through a 395 nm filter and compared with an internal calibration curve, to provide a reading on the LED display that ranges from 0.05 Endotoxin Units (EU)/ml to 5 EU/ml. Several surface sites were analyzed within ISS between March 2007 and February 2008, including multiple locations in the US Laboratory Destiny, Node 1 Unity, AMock, and Service Module Zvezda

  4. Rapid Feedback Assessment Methods: Can We Improve Engagement and Preparation for Exams in Large-Enrollment Courses?

    Science.gov (United States)

    Cotner, Sehoya H.; Fall, Bruce A.; Wick, Susan M.; Walker, J. D.; Baepler, Paul M.

    2008-01-01

    Scratch-off immediate feedback assessment technique (IF-AT) forms and classroom response systems (clickers) can increase student engagement and interaction and help students prepare for exams by indicating the type and level of questions they will encounter. We used the IF-AT throughout the semester in three sections of a lower-division biology…

  5. Preparation of recombinant firefly luciferase by a simple and rapid expression and purification method and its application in bacterial detection

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A simple and rapid expression and purification method of recombinant firefly luciferase was developed for bacteria detection. A modified luciferase gene from North American firefly Photinus pyralis was cloned into pET28a expression vector and the recombinant protein was produced in Escherichia coli BL21. The recombinant luciferase,equipped with a polyhistidine affinity tag,was purified by immobilized metal ion affinity chromatography (IMAC). The approach generated an abundant expression and an efficient pur...

  6. 密度梯度碳/碳复合材料的制备及性能%Preparation and Properties of Density Gradient Carbon/Carbon Composites

    Institute of Scientific and Technical Information of China (English)

    陈强; 张守阳

    2011-01-01

    采用强制流动热梯度化学气相渗透法在1000~1250℃制备了密度梯度碳/碳复合材料;借助三点弯曲试验和激光闪烁法测定了复合材料的弯曲性能与导热系数,用偏光显微镜及扫描电子显微镜观察了基体热解碳的组织结构及断口形貌。结果表明:该复合材料上层的最大密度为1.65g·cm^-3,下层的最小密度为1.10g·cm^-3,具有明显的密度梯度;复合材料的密度越大,抗弯强度越高;其导热系数也随密度的增加而增大;沉积温度是影响基体热解碳组织的主要因素,高温有利于粗糙层热解碳的生成,而低温有利于光滑层热解碳的生成。%Density gradient carbon/carbon composites were infiltrated using forced flow thermal gradient chemical vapor infiltration in the range of 1 000- 1 250℃. Flexural strength and thermal conductivity were determined by 3 point bending test and laser flashing method. Mierostructure of deposited pyrolytic carbon and morphology of fracture surface were observed by polarized light microscopy and scanning electron microscopy. The results show that maximal density of upper part of the composites was 1.65 g · cm^-3 , while miniumum density of bottom part was 1. 10 g ·em^-3 , and obvions density gradient was found. Flexural strength and coefficient of thermal conductivity increased with the increase of density of the composites. The deposition temperature had a great impact on the mierostrueture of the pyolytic carbon. A higher temperature was favourable for the formation of rough layer hydrocarbon, while a lower temperature was favourable for the formation of smooth layer hydrocarbon.

  7. Rapid Preparation Methods of Biological Samples for Ionic Compounds Using Ion Exchange Type Monolithic Silica Spin Column

    OpenAIRE

    宮崎, 将太; 山田, 智子; 太田, 茂徳; 斉藤, 剛; 奈女良, 昭; 大平, 真義

    2010-01-01

    We developed a device comprising a spin column packed with ion exchange type (SCX and SAX) monolithic silica for extracting ionic compounds from biological samples. The methods involving the use of these spin column are not useful for the extraction of ionic analytes, but are highly reproducible for the analysis in serum and urine. This spin column enabled sample preparation in less than 10 min. Handling such as sample loading, washing, and elution of analytes, was exhibited by the centrifuga...

  8. Structural, optical and magnetic properties of porous alpha-Fe2O3 nanostructures prepared by rapid combustion method.

    Science.gov (United States)

    Manikandan, A; Vijaya, J Judith; Kennedy, L John

    2013-04-01

    Porous iron oxide (alpha-Fe2O3) nanoparticles were synthesized by the microwave combustion method (MCM) using urea as the fuel. For the purpose of comparison, it was also prepared using the conventional combustion method (CCM). The as-synthesized porous alpha-Fe2O3 nanoparticles were characterized by X-ray powder diffraction (XRD), high resolution scanning electron microscopy (HR-SEM), high resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray analysis (EDX), diffuse reflectance spectroscopy (DRS), Brunauer-Emmett-Teller (BET) analysis and vibrating sample magnetometer (VSM) analysis. The XRD results confirmed the formation of rhombohedral alpha-Fe2O3 phase. The formation of alpha-Fe2O3 nanoparticles was confirmed by HR-SEM and HR-TEM, and their possible formation mechanisms were also proposed. The optical absorption and the band gap were determined by DRS spectra. The surface area was derived from the nitrogen adsorption-desorption isotherms using BET analysis. The magnetic properties of the synthesized alpha-Fe2O3 were investigated with vibrating sample magnetometer (VSM) and their hysteresis loops were obtained. Both the prepared samples show ferromagnetic behavior with hysteresis curve at room temperature. The relatively high saturation magnetization (65.23 emu/g) of alpha-Fe2O3-MCM suggests that this method is suitable for preparing high-quality nanocrystalline magnetic alpha-Fe2O3 for practical applications.

  9. Rapid freezing cryo-polymerization and microchannel liquid-flow focusing for cryogel beads: adsorbent preparation and characterization of supermacroporous bead-packed bed.

    Science.gov (United States)

    Yun, Junxian; Dafoe, Julian T; Peterson, Eric; Xu, Linhong; Yao, Shan-Jing; Daugulis, Andrew J

    2013-04-05

    Cryogel beads, fabricated by the microchannel liquid-flow focusing and cryo-polymerization method, have micron-scale supermacropores allowing the passage of crude feedstocks, and could be of interest as chromatographic adsorbents in bioseparation applications. In this work, we provide a rapid freezing and continuous formation method for cryogel beads by cryo-polymerization using dry ice particles as the freezing source and microchannel liquid-flow focusing using peristaltic pumps for the fluid supply. Polyacrylamide (pAAm)-based supermacroporous cryogel beads were prepared and grafted with N,N-dimethylaminoethyl methacrylate (DMAEMA), which provided the anion-exchange cryogel beads with tertiary amine functional groups suitable for binding proteins. Properties of the supermacroporous cryogel-bead packed bed, i.e., permeability, bed voidage, protein breakthrough as well as protein adsorption performance by using bovine γ-globulin as model protein, were experimentally investigated. A capillary-based model was employed to characterize the supermacroporous bed performance, and gave a reasonable description of the microstructure and thus an insight into the flow, dispersion and mass transfer behaviors within the cryogel bead-packed bed. The results also showed that by using dry ice as the freezing source, it is easy to reduce the temperature below -55 to -61°C in the bulk solution, causing the rapid formation of ice crystals within the monomer drops, and finally effective cryo-polymerization to form supermacropores within the cryogel beads. By using peristaltic pumps, continuous preparation was achieved and the obtained cryogel beads had favorable properties similar to those prepared using syringe pumps in the microchannel liquid-flow focusing process. This method is thus expected to be interesting in the liter- or even larger-scale preparation of cryogel adsorbents.

  10. Preparation of {sup 183,184}Re samples for modelling a rapid gas phase chemistry of Nielsbohrium (Ns), element 107

    Energy Technology Data Exchange (ETDEWEB)

    Eichler, R.; Gaeggeler, H.W.; Eichler, B.; Tuerler, A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-09-01

    Chemical gas phase reactions of the heavier group 7 elements in the system O{sub 2}/H{sub 2}O are presumably best suited for a separation of Nielsbohrium from the lighter transactinides. We expect a higher reaction velocity using the more reactive gas system O{sub 3}/H{sub 2}O{sub 2}. For the experimental verification of this idea we prepared {sup 183}Re/{sup 184}Re samples for thermochromatography experiments with both gas systems. (author) 8 refs.

  11. Ambient Filtration Method To Rapidly Prepare Highly Conductive, Paper-Based Porous Gold Films for Electrochemical Biosensing.

    Science.gov (United States)

    Guntupalli, Bhargav; Liang, Pingping; Lee, Jung-Hoon; Yang, Yuehai; Yu, Haixiang; Canoura, Juan; He, Jin; Li, Wenzhi; Weizmann, Yossi; Xiao, Yi

    2015-12-16

    Thin gold films offer intriguing material properties for potential applications including fuel cells, supercapacitors, and electronic and photonic devices. We describe here an ambient filtration method that provides a simple and novel way to generate rapidly porous and thin gold films without the need for sophisticated instruments, clean-room environments, and any postgrowth process or sintering steps. Using this approach, we can fabricate highly conductive gold films composed of gold nanoparticles layered atop a matrix of metallic single-walled carbon nanotubes on mixed cellulose ester filter paper within 20 min. These hybrid films (thickness ∼40 nm) exhibit fast electron transfer and excellent electrocatalytic properties that are similar to purchased gold films, but with a larger electroactive surface that lends itself to more sensitive analyte detection. We used the neurotransmitters dopamine and serotonin as benchmark analytes to demonstrate that our hybrid gold films can clearly discriminate the presence of both molecules in a mixture with resolution that greatly exceeds that of either purchased gold slides or electrodeposited gold films. Importantly, we postulate that this new approach could readily be generalized for the rapid fabrication of films from various other metals under ambient conditions, and could also be used as a prelude to transferring the resulting films onto glass or other flexible substrates.

  12. A rapid, one step preparation for measuring selected free plus SO2-bound wine carbonyls by HPLC-DAD/MS.

    Science.gov (United States)

    Han, Guomin; Wang, Hua; Webb, Michael R; Waterhouse, Andrew L

    2015-03-01

    Carbonyl compounds are produced during fermentation and chemical oxidation during wine making and aging, and they are important to wine flavor and color stability. Since wine also contains these compounds as α-hydroxysulfonates as a result of their reaction with sulfur dioxide, an alkaline pre-treatment requiring oxygen exclusion has been used to release these bound carbonyls for analysis. By modifying the method to hydrolyze the hydroxysulfonates with heating and acid in the presence of 2,4-dinitrophenylhydrazine (DNPH), the carbonyl compounds are simultaneously and quickly released and derivatized, resulting in a simpler and more rapid method. In addition, the method avoids air exclusion complications during hydrolysis by the addition of sulfur dioxide. The method was optimized for temperature, reaction time, and the concentrations of DNPH, sulfur dioxide and acid. The hydrazones were shown to be stable for 10 h, adequate time for chromatographic analysis by HPLC-DAD/MS. This method is demonstrated for 2-ketoglutaric acid, pyruvic acid, acetoin and acetaldehyde, wine carbonyls of very different reactivities, and it offers good specificity, high recovery and low limits of detection. This new rapid, simple method is demonstrated for the measurement of carbonyl compounds in a range of wines of different ages and grape varieties. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Technical Note: An improved guideline for rapid and precise sample preparation of tree-ring stable isotope analysis

    Science.gov (United States)

    Schollaen, K.; Baschek, H.; Heinrich, I.; Helle, G.

    2015-07-01

    The procedure of wood sample preparation, including tree-ring dissection, cellulose extraction, homogenization and finally weighing and packing for stable isotope analysis is labour intensive and time consuming. We present an elaborated methodical guideline from pre-analyses considerations, wood sample preparation through semi-automated chemical extraction of cellulose directly from tree-ring cross-sections to tree-ring dissection for high-precision isotope ratio mass spectrometry. This guideline reduces time and maximizes the tree-ring stable isotope data throughput significantly. The method was applied to ten different tree species (coniferous and angiosperm wood) with different wood growth rates and differently shaped tree-ring boundaries. The tree-ring structures of the cellulose cross-sections largely remained well identifiable. FTIR (Fourier transform infrared) spectrometry and the comparison of stable isotope values with classical method confirm chemical purity of the resultant cellulose. Sample homogenization is no longer necessary. Cellulose extraction is now faster, cheaper and more user friendly allowing (i) the simultaneous treatment of wood cross-sections of a total length of 180 cm (equivalent to 6 increment cores of 30 cm length) and thickness of 0.5 to 2 mm, and (ii) precise tree-ring separation at annual to high-resolution scale utilizing manual devices or UV-laser microdissection microscopes.

  14. Technical Note: An improved guideline for rapid and precise sample preparation of tree-ring stable isotope analysis

    Directory of Open Access Journals (Sweden)

    K. Schollaen

    2015-07-01

    Full Text Available The procedure of wood sample preparation, including tree-ring dissection, cellulose extraction, homogenization and finally weighing and packing for stable isotope analysis is labour intensive and time consuming. We present an elaborated methodical guideline from pre-analyses considerations, wood sample preparation through semi-automated chemical extraction of cellulose directly from tree-ring cross-sections to tree-ring dissection for high-precision isotope ratio mass spectrometry. This guideline reduces time and maximizes the tree-ring stable isotope data throughput significantly. The method was applied to ten different tree species (coniferous and angiosperm wood with different wood growth rates and differently shaped tree-ring boundaries. The tree-ring structures of the cellulose cross-sections largely remained well identifiable. FTIR (Fourier transform infrared spectrometry and the comparison of stable isotope values with classical method confirm chemical purity of the resultant cellulose. Sample homogenization is no longer necessary. Cellulose extraction is now faster, cheaper and more user friendly allowing (i the simultaneous treatment of wood cross-sections of a total length of 180 cm (equivalent to 6 increment cores of 30 cm length and thickness of 0.5 to 2 mm, and (ii precise tree-ring separation at annual to high-resolution scale utilizing manual devices or UV-laser microdissection microscopes.

  15. Fourier transform mid-infrared (MIR) and near-infrared (NIR) spectroscopy for rapid quality assessment of Chinese medicine preparation Honghua Oil.

    Science.gov (United States)

    Wu, Yan-Wen; Sun, Su-Qin; Zhou, Qun; Leung, Hei-Wun

    2008-02-13

    Honghua Oil (HHO), a traditional Chinese medicine (TCM) oil preparation, is a mixture of several plant essential oils. In this text, the extended ranges of Fourier transform mid-infrared (FT-MIR) and near infrared (FT-NIR) were recorded for 48 commercially available HHOs of different batches from nine manufacturers. The qualitative and quantitative analysis of three marker components, alpha-pinene, methyl salicylate and eugenol, in different HHO products were performed rapidly by the two vibrational spectroscopic methods, i.e. MIR with horizontal attenuated total reflection (HATR) accessory and NIR with direct sampling technique, followed by partial least squares (PLS) regression treatment of the set of spectra obtained. The results indicated that it was successful to identify alpha-pinene, methyl salicylate and eugenol in all of the samples by simple inspection of the MIR-HATR spectra. Both PLS models established with MIR-HATR and NIR spectral data using gas chromatography (GC) peak areas as calibration reference showed a good linear correlation for each of all three target substances in HHO samples. The above spectroscopic techniques may be the promising methods for the rapid quality assessment/quality control (QA/QC) of TCM oil preparations.

  16. Antibacterial performance of Ag nanoparticles and AgGO nanocomposites prepared via rapid microwave-assisted synthesis method

    Science.gov (United States)

    Chook, Soon Wei; Chia, Chin Hua; Zakaria, Sarani; Ayob, Mohd Khan; Chee, Kah Leong; Huang, Nay Ming; Neoh, Hui Min; Lim, Hong Ngee; Jamal, Rahman; Rahman, Raha Mohd Fadhil Raja Abdul

    2012-09-01

    Silver nanoparticles and silver-graphene oxide nanocomposites were fabricated using a rapid and green microwave irradiation synthesis method. Silver nanoparticles with narrow size distribution were formed under microwave irradiation for both samples. The silver nanoparticles were distributed randomly on the surface of graphene oxide. The Fourier transform infrared and thermogravimetry analysis results showed that the graphene oxide for the AgNP-graphene oxide (AgGO) sample was partially reduced during the in situ synthesis of silver nanoparticles. Both silver nanoparticles and AgGO nanocomposites exhibited stronger antibacterial properties against Gram-negative bacteria ( Salmonella typhi and Escherichia coli) than against Gram-positive bacteria ( Staphyloccocus aureus and Staphyloccocus epidermidis). The AgGO nanocomposites consisting of approximately 40 wt.% silver can achieve antibacterial performance comparable to that of neat silver nanoparticles.

  17. Rapid mass spectrometric analysis of 15N-Leu incorporation fidelity during preparation of specifically labeled NMR samples

    DEFF Research Database (Denmark)

    Truhlar, Stephanie M E; Cervantes, Carla F; Torpey, Justin W

    2008-01-01

    Advances in NMR spectroscopy have enabled the study of larger proteins that typically have significant overlap in their spectra. Specific (15)N-amino acid incorporation is a powerful tool for reducing spectral overlap and attaining reliable sequential assignments. However, scrambling of the label...... during protein expression is a common problem. We describe a rapid method to evaluate the fidelity of specific (15)N-amino acid incorporation. The selectively labeled protein is proteolyzed, and the resulting peptides are analyzed using MALDI mass spectrometry. The (15)N incorporation is determined...... by analyzing the isotopic abundance of the peptides in the mass spectra using the program DEX. This analysis determined that expression with a 10-fold excess of unlabeled amino acids relative to the (15)N-amino acid prevents the scrambling of the (15)N label that is observed when equimolar amounts are used...

  18. A lab-on-a-chip system with integrated sample preparation and loop-mediated isothermal amplification for rapid and quantitative detection of Salmonella spp. in food samples.

    Science.gov (United States)

    Sun, Yi; Quyen, Than Linh; Hung, Tran Quang; Chin, Wai Hoe; Wolff, Anders; Bang, Dang Duong

    2015-04-21

    Foodborne disease is a major public health threat worldwide. Salmonellosis, an infectious disease caused by Salmonella spp., is one of the most common foodborne diseases. Isolation and identification of Salmonella by conventional bacterial culture or molecular-based methods are time consuming and usually take a few hours to days to complete. In response to the demand for rapid on line or on site detection of pathogens, in this study, we describe for the first time an eight-chamber lab-on-a-chip (LOC) system with integrated magnetic bead-based sample preparation and loop-mediated isothermal amplification (LAMP) for rapid and quantitative detection of Salmonella spp. in food samples. The whole diagnostic procedures including DNA isolation, isothermal amplification, and real-time detection were accomplished in a single chamber. Up to eight samples could be handled simultaneously and the system was capable to detect Salmonella at concentration of 50 cells per test within 40 min. The simple design, together with high level of integration, isothermal amplification, and quantitative analysis of multiple samples in short time, will greatly enhance the practical applicability of the LOC system for rapid on-site screening of Salmonella for applications in food safety control, environmental surveillance, and clinical diagnostics.

  19. Mn3O4 nano-sized crystals: Rapid synthesis and extension to preparation of nanosized LiMn2O4 materials

    Indian Academy of Sciences (India)

    Xiao-Ling Cui; Yong-Li Li; Shi-You Li; Guo-Cun Sun; Jin-Xia Ma; Lu Zhang; Tian-Ming Li; Rong-Bo Ma

    2014-05-01

    With a novel gas-liquid reaction, a facile and rapid method has been successfully developed for the synthesis of nano-sized Mn3O4 crystals. Coupled with complementary experiments, preparation mechanisms of Mn(II) and Mn(III)Mn(III)Mn(II) coordination complexes as well as nano-sized Mn3O4 crystals are studied. Besides, as the extension of synthesis of nano-sized Mn3O4 crystals, the intermediate ammonia alkaline solution containing Mn(III)Mn(III)Mn(II) coordination complexes, which tend to decompose into nano-sized Mn3O4 crystals spontaneously, are used to prepare nanosized LiMn2O4 materials. Although any physical treatment has been done to disperse powders, the as-synthesized LiMn2O4 nanoparticles are still existence with homogeneous size distribution (about 24.2 nm) without any obvious agglomeration. That is to say, the novel method is constructive not only to accelerate reaction rates for the elevated oxidation state of manganese ions, but also to prepare dispersed nanosized LiMn2O4 materials with good electrochemical properties.

  20. Investigation of stacked elemental layers for Cu(In,Ga)Se{sub 2} thin film preparation by rapid thermal selenization

    Energy Technology Data Exchange (ETDEWEB)

    Stroth, Christiane; Ohland, Joerg; Mikolajczak, Ulf; Madena, Thomas; Keller, Jan; Parisi, Juergen; Hammer, Maria; Riedel, Ingo [Energy and Semiconductor Research Laboratory, Department of Physics, University of Oldenburg, 26111 Oldenburg (Germany)

    2013-07-01

    Rapid thermal selenization of pure metallic (Cu-In-Ga) or selenium-containing (Cu-In-Ga-Se) precursors is a favorable method to fabricate Cu(In,Ga)Se{sub 2} absorber films for application in thin film solar cells. Because of its upscaling potential and the short process time it is a promising approach for the fabrication of CIGSe photovoltaic modules on industrial scale. As a preliminary work for prospective plasma-enhanced selenization of stacked elemental layers (SEL) the elements copper, indium and gallium were sequentially deposited on molybdenum coated soda-lime glass by thermal evaporation. The stacking order was varied and the precursors were annealed with different heating rates. Morphology, elemental depth distribution and phases of the layers were investigated before and after annealing using scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. Furthermore the influence of different heating rates on phase transitions during annealing was studied by in-situ X-ray diffraction.

  1. Nanostructured Hypoeutectic Fe-B Alloy Prepared by a Self-propagating High Temperature Synthesis Combining a Rapid Cooling Technique

    Directory of Open Access Journals (Sweden)

    Fu Licai

    2008-01-01

    Full Text Available Abstract We have successfully synthesized bulk nanostructured Fe94.3B5.7 alloy using the one-step approach of a self-propagating high temperature synthesis (SHS combining a rapid cooling technique. This method is convenient, low in cost, and capable of being scaled up for processing the bulk nanostructured materials. The solidification microstructure is composed of a relatively coarse, uniformly distributed dendriteto a nanostructured eutectic matrix with α-Fe(B and t-Fe2B phases. The fine eutectic structure is disorganized, and the precipitation Fe2B is found in the α-Fe(B phase of the eutectic. The dendrite phase has the t-Fe2B structure rather than α-Fe(B in the Fe94.3B5.7 alloy, because the growth velocity of t-Fe2B is faster than that of the α-Fe with the deeply super-cooling degree. The coercivity (Hc and saturation magnetization (Ms values of the Fe94.3B5.7 alloy are 11 A/m and 1.74T, respectively. Moreover, the Fe94.3B5.7 alloy yields at 1430 MPa and fractures at 1710 MPa with a large ductility of 19.8% at compressive test.

  2. Simple and rapid preparation of red fluorescence and red color S. aureus derived nanobioparticles for pathogen detection.

    Science.gov (United States)

    Hu, Wei; Zhang, Yun; Yang, Hang; Yu, Junping; Wei, Hongping

    2015-08-01

    In this study, a simple and rapid method was developed to transform protein A producing Staphylococcus aureus cells into red color and red fluorescent nanobioparticles, which were homogeneous, dispersive and relatively stable with a uniform size of 800 nm. The method consists of reaction with a monotetrazolium redox dye at 25°C for 15 min and heat inactivation at 65°C for 30 min. This method provided the first S. aureus nanobioparticles with the dual property of red color and red fluorescence. Attributed to the IgG binding site known as protein A on their surface, the nanobioparticles could be used as vectors for immunoassays of many bacteria and viruses. Coagglutination test of Escherichia coli O157:H7 observed by naked eyes showed that the detection limitation of the nanobioprobes was 1∗10(6) CFU/ml, which was about 100 times more sensitive than the natural uncolored S. aureus bioprobes. Red fluorescence detection and analysis of the coagglutination product by a microplate reader lowered the detection limit to 2.5∗10(4) CFU/ml. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Sample preparation and direct electrospray ionization on a tip column for rapid mass spectrometry analysis of complex samples.

    Science.gov (United States)

    Huang, Yun-Qing; You, Jin-Qing; Yuan, Bi-Feng; Feng, Yu-Qi

    2012-10-07

    A handheld pipette tip column electrospray ionization source (PTC-ESI source) was developed for rapid mass spectrometry analysis at ambient pressure. The PTC-ESI source was made up of three main component parts including a micro DC high voltage (HV) power supply, a micropipette and a disposable micropipette tip filled with a plug of adsorbent. A DC high voltage was applied to the sharp point of the micropipette tip column to induce electrospray ionization. The PTC-ESI source was successfully used for direct analysis of basic organic compounds, organic acids and peptides in a simple matrix. In the case of complex samples, micro-extraction based on the adsorbent phase filled in the pipette tip was used to remove impurities and concentrate target analytes prior to ionization. The eluting solution was not pipetted out, but directly dispersed in the form of electrospray from the pipette tip for ionization. The effectiveness of the PTC-ESI source has been further demonstrated by fast analysis of therapeutic compounds and endogenous bioactive chemicals in complex biological samples.

  4. Rapid "one-pot" preparation of polymeric monolith via photo-initiated thiol-acrylate polymerization for capillary liquid chromatography.

    Science.gov (United States)

    Bai, Jingyao; Wang, Hongwei; Ou, Junjie; Liu, Zhongshan; Shen, Yehua; Zou, Hanfa

    2016-06-21

    A facile approach was exploited for fast preparation of polymer-based monoliths in UV-transparent fused-silica capillaries via "one-pot" photo-initiated thiol-acrylate polymerization reaction of dipentaerythritolpenta-/hexaacrylate (DPEPA) and 1-octadecanethiol (ODT) in the presence of porogenic solvents (1-butanol and ethylene glycol). Due to relative insensitivity of oxygen inhibition in thiol-ene free-radical polymerization, the polymerization could be performed within 5 min. The effects of composition of prepolymerization solution on the morphology and permeability of poly(ODT-co-DPEPA) monoliths were investigated in detail by adjusting the content of monomer and binary porogen ratio. The physical properties of poly(ODT-co-DPEPA) monoliths were characterized by Fourier transform infrared spectroscopy (FT-IR), mercury intrusion porosimetry (MIP) and nitrogen adsorption/desorption measurement. The evaluation of chromatographic performance was carried out by capillary liquid chromatography (cLC). The results indicated that the poly(ODT-co-DPEPA) monolith was homogeneous and permeable, and also possessed a typical reversed-phase retention mechanism in cLC with high efficiency (∼75,000 N m(-1)) for separation of alkylbenzenes. Eventually, the further separation of tryptic digest of proteins by cLC tandem mass spectrometry (cLC-MS/MS) demonstrated its potential in the analysis of biological samples.

  5. Thermal Stability of P-Type BiSbTe Alloys Prepared by Melt Spinning and Rapid Sintering

    Directory of Open Access Journals (Sweden)

    Yun Zheng

    2017-06-01

    Full Text Available P-type BiSbTe alloys have been widely implemented in waste heat recovery from low-grade heat sources below 600 K, which may involve assorted environments and conditions, such as long-term service, high-temperature exposure (generally 473–573 K and mechanical forces. It is important to evaluate the service performance of these materials in order to prevent possible failures in advance and extend the life cycle. In this study, p-type Bi0.5Sb1.5Te3 commercial zone-melting (ZM ingots were processed by melt spinning and subsequent plasma-activated sintering (MS-PAS, and were then subjected to vacuum-annealing at 473 and 573 K, respectively, for one week. The results show that MS-PAS samples exhibit excellent thermal stability when annealed at 473 K. However, thermal annealing at 573 K for MS-PAS specimens leads to the distinct sublimation of the element Te, which degrades the hole concentration remarkably and results in inferior thermoelectric performance. Furthermore, MS-PAS samples annealed at 473 K demonstrate a slight enhancement in flexural and compressive strengths, probably due to the reduction of residual stress induced during the sintering process. The current work guides the reliable application of p-type Bi0.5Sb1.5Te3 compounds prepared by the MS-PAS technique.

  6. Rapid sample preparation method for LC-MS/MS or GC-MS analysis of acrylamide in various food matrices.

    Science.gov (United States)

    Mastovska, Katerina; Lehotay, Steven J

    2006-09-20

    A fast and easy sample preparation procedure for analysis of acrylamide in various food matrices was developed and optimized. In its first step, deuterated acrylamide internal standard is added to 1 g of homogenized sample together with 5 mL of hexane, 10 mL of water, 10 mL of acetonitrile, 4 g of MgSO4, and 0.5 g of NaCl. Water facilitates the extraction of acrylamide; hexane serves for sample defatting; and the salt combination induces separation of water and acetonitrile layers and forces the majority of acrylamide into the acetonitrile layer. After vigorous shaking of the extraction mixture for 1 min and centrifugation, the upper hexane layer is discarded and a 1 mL aliquot of the acetonitrile extract is cleaned up by dispersive solid-phase extraction using 50 mg of primary secondary amine sorbent and 150 mg of anhydrous MgSO4. The final extract is analyzed either by liquid chromatography-tandem mass spectrometry or by gas chromatography-mass spectrometry (in positive chemical ionization mode) using the direct sample introduction technique for rugged large-volume injection.

  7. Thermal Stability of P-Type BiSbTe Alloys Prepared by Melt Spinning and Rapid Sintering.

    Science.gov (United States)

    Zheng, Yun; Tan, Gangjian; Luo, Yubo; Su, Xianli; Yan, Yonggao; Tang, Xinfeng

    2017-06-06

    P-type BiSbTe alloys have been widely implemented in waste heat recovery from low-grade heat sources below 600 K, which may involve assorted environments and conditions, such as long-term service, high-temperature exposure (generally 473-573 K) and mechanical forces. It is important to evaluate the service performance of these materials in order to prevent possible failures in advance and extend the life cycle. In this study, p-type Bi0.5Sb1.5Te₃ commercial zone-melting (ZM) ingots were processed by melt spinning and subsequent plasma-activated sintering (MS-PAS), and were then subjected to vacuum-annealing at 473 and 573 K, respectively, for one week. The results show that MS-PAS samples exhibit excellent thermal stability when annealed at 473 K. However, thermal annealing at 573 K for MS-PAS specimens leads to the distinct sublimation of the element Te, which degrades the hole concentration remarkably and results in inferior thermoelectric performance. Furthermore, MS-PAS samples annealed at 473 K demonstrate a slight enhancement in flexural and compressive strengths, probably due to the reduction of residual stress induced during the sintering process. The current work guides the reliable application of p-type Bi0.5Sb1.5Te₃ compounds prepared by the MS-PAS technique.

  8. Simple and rapid preparation of [{sup 11}C]DASB with high quality and reliability for routine applications

    Energy Technology Data Exchange (ETDEWEB)

    Haeusler, D.; Mien, L.-K. [Department of Nuclear Medicine, PET, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria); Department of Pharmaceutical Technology and Biopharmaceutics, University of Vienna, A-1090 Vienna (Austria); Nics, L. [Department of Nuclear Medicine, PET, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria); Department of Nutritional Sciences, University of Vienna, A-1090 Vienna (Austria); Ungersboeck, J. [Department of Nuclear Medicine, PET, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria); Department of Inorganic Chemistry, University of Vienna, A-1090 Vienna (Austria); Philippe, C. [Department of Nuclear Medicine, PET, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria); Department of Pharmaceutical Technology and Biopharmaceutics, University of Vienna, A-1090 Vienna (Austria); Lanzenberger, R.R. [Department of Psychiatry and Psychotherapy, Medical University of Vienna, A-1090 Vienna (Austria); Kletter, K.; Dudczak, R. [Department of Nuclear Medicine, PET, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria); Mitterhauser, M. [Department of Nuclear Medicine, PET, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria); Department of Pharmaceutical Technology and Biopharmaceutics, University of Vienna, A-1090 Vienna (Austria); Hospital Pharmacy of the General Hospital of Vienna, A-1090 Vienna (Austria); Wadsak, W. [Department of Nuclear Medicine, PET, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria); Department of Inorganic Chemistry, University of Vienna, A-1090 Vienna (Austria)], E-mail: wolfgang.wadsak@meduniwien.ac.at

    2009-09-15

    [{sup 11}C]DASB combines all major prerequisites for a successful SERT-ligand, providing excellent biological properties and in-vivo behaviour. Thus, we aimed to establish a fully automated procedure for the synthesis and purification of [{sup 11}C]DASB with a high degree of reliability reducing the overall synthesis time while conserving high yields and purity. The optimized [{sup 11}C]DASB synthesis was applied in more than 60 applications with a very low failure rate (3.2%). We obtained yields up to 8.9 GBq (average 5.3{+-}1.6 GBq). Radiochemical yields based on [{sup 11}C]CH{sub 3}I, (corrected for decay) were 66.3{+-}6.9% with a specific radioactivity (A{sub s}) of 86.8{+-}24.3 GBq/{mu}mol (both at the end of synthesis, EOS). Time consumption was kept to a minimum, resulting in 43 min from end of bombardment to release of the product after quality control. Form our data, it is evident that the presented method can be implemented for routine preparations of [{sup 11}C]DASB with high reliability.

  9. Rapid Preparation of Biosorbents with High Ion Exchange Capacity from Rice Straw and Bagasse for Removal of Heavy Metals

    Directory of Open Access Journals (Sweden)

    Supitcha Rungrodnimitchai

    2014-01-01

    Full Text Available This work describes the preparation of the cellulose phosphate with high ion exchange capacity from rice straw and bagasse for removal of heavy metals. In this study, rice straw and bagasse were modified by the reaction with phosphoric acid in the presence of urea. The introduced phosphoric group is an ion exchangeable site for heavy metal ions. The reaction by microwave heating yielded modified rice straw and modified bagasse with greater ion exchange capacities (∼3.62 meq/g and shorter reaction time (1.5–5.0 min than the phosphorylation by oil bath heating. Adsorption experiments towards Pb2+, Cd2+, and Cr3+ ions of the modified rice straw and the modified bagasse were performed at room temperature (heavy metal concentration 40 ppm, adsorbent 2.0 g/L. The kinetics of adsorption agreed with the pseudo-second-order model. It was shown that the modified rice straw and the modified bagasse could adsorb heavy metal ions faster than the commercial ion exchange resin (Dowax. As a result of Pb2+ sorption test, the modified rice straw (RH-NaOH 450W removed Pb2+ much faster in the initial step and reached 92% removal after 20 min, while Dowax (commercial ion exchange resin took 90 min for the same removal efficiency.

  10. In vitro degradation and cytocompatibility of dicalcium phosphate dihydrate cements prepared using the monocalcium phosphate monohydrate/hydroxyapatite system reveals rapid conversion to HA as a key mechanism.

    Science.gov (United States)

    Alge, Daniel L; Goebel, W Scott; Chu, Tien-Min Gabriel

    2012-04-01

    We previously showed that dicalcium phosphate dihydrate (DCPD) cements can be prepared using monocalcium phosphate monohydrate (MCPM) and hydroxyapatite (HA). In this study, we have characterized the degradation properties and biocompatibility of these novel cements. To study the degradation properties, cements were prepared using MCPM:HA molar ratios of 4:1, 2:1, 2:3, and 2:5. Degradation was evaluated in vitro by static soaking in PBS, and changes in pH, mass, compressive strength, and composition were monitored. Conversion of DCPD to HA was noted in the 4:1 group, which initially consisted of pure DCPD. However, the 2:1 group, which initially consisted of DCPD and an intermediate amount of unreacted HA, underwent rapid conversion to HA associated with significantly greater pH drop and mass loss as well as a complete loss of mechanical integrity. On the basis of these results, we directly compared the cytocompatibility of 2:1 MCPM:HA cements to DCPD cements prepared with an equivalent percent molar excess of β-tricalcium phosphate (β-TCP) using an in vitro cell viability assay. Viability of cells co-cultured with 2:1 MCPM:HA cements was significantly reduced after just 48 h, while viability of cells cultured with the β-TCP-based cements was no different from control cells. In conclusion, this study demonstrates that conversion to HA plays an important role in the degradation of DCPD cements prepared with the MCPM/HA system, affecting both physical properties and cytocompatibility. These results could have important clinical implications for MCPM/HA cements.

  11. Growth of fibroblasts and endothelial cells on wettability gradient surfaces

    NARCIS (Netherlands)

    Ruardy, TG; Moorlag, HE; Schakenraad, JM; VanderMei, HC; Busscher, HJ

    1997-01-01

    The growth, spreading, and shape of human skin fibroblasts (PK 84) and human umbilical cord endothelial cells on dichlorodimethylsilane (DDS) and dimethyloctadecylchlorosilane (DOGS) gradient surfaces were investigated in the presence of serum proteins. Gradient surfaces were prepared on glass using

  12. THE EFFECT OF PREPARATION CONDITIONS OF RAPIDLY SOLIDIFIED IRON BASED GRANULES ON PROPERTIES OF COMPOSITE MATERIAL FORMED BY CASTING TECHNOLOGY

    Directory of Open Access Journals (Sweden)

    A. S. Kalinichenko

    2017-01-01

    Full Text Available The variety of requirements for friction pairs requires the development of different technologies for the production of tribological materials with reference to the operation modes. Composite materials obtained by the casting technology have been successfully applied for the normalization of the thermomechanical state of the steam turbines. These composites consist of the matrix based on copper alloys reinforced with cast iron granules. Because the structure and properties of cast iron are determined by the conditions of their production studies have been conducted on determination of preparation conditions on grain structure and properties of the synthesized composite material. Using an upgraded unit for production of granules technological regimes were determined providing narrow fractional composition. It has been found that granules formed are characterized with typical microstructure of white cast iron containing perlite and ledeburite. Microhardness of pilot cast iron granules is characterized by high values (from 7450 up to 9450 MPa and depends on the size of the fraction. Composite materials obtained using experimental granules had a microhardness of the reinforcing cast iron granules about 3500 MPa, and a bronze matrix – 1220 MPa, which is higher than the hardness of the composite material obtained by using the annealed DCL-1granules (2250 MPa. Metal base of experimental granules in the composite material has the structure of perlitic ductile iron with inclusions of ferrite not exceeding 10–15% and set around a flocculent graphite. As a result, the increase of physical-mechanical properties of finished products made of composite material is observed. 

  13. Photocatalytic reduction of CO2 over Ag/TiO2 nanocomposites prepared with a simple and rapid silver mirror method

    Science.gov (United States)

    Yu, Bingcheng; Zhou, Yong; Li, Peng; Tu, Wenguang; Li, Ping; Tang, Lanqin; Ye, Jinhua; Zou, Zhigang

    2016-06-01

    The photocatalytic reduction of CO2 over Ag/TiO2 composites prepared with a simple silver mirror reaction method was investigated under UV-visible irradiation in both gas-phase (CO2 + water vapor) and aqueous solution (CO2-saturated NaHCO3 solution) systems. The as-prepared Ag/TiO2 nanocomposite exhibits efficient photocatalytic activity due to the surface plasmonic resonance and electron sink effect of the Ag component, which was found to be closely related to the size and loading amount of Ag. The rapid silver method is effective at curbing the size of Ag, so photocatalytic activity can be improved. Diverse organic chemical products were detected, including mainly methane and methanol as well as a small amount of C2 and C3 species such as acetaldehyde and acetone. Possible photocatalytic mechanisms were proposed. This artificial photosynthesis process may give a prosperous route to the removal of CO2 while simultaneously converting CO2 to valuable fuels based on highly efficient photocatalysts.The photocatalytic reduction of CO2 over Ag/TiO2 composites prepared with a simple silver mirror reaction method was investigated under UV-visible irradiation in both gas-phase (CO2 + water vapor) and aqueous solution (CO2-saturated NaHCO3 solution) systems. The as-prepared Ag/TiO2 nanocomposite exhibits efficient photocatalytic activity due to the surface plasmonic resonance and electron sink effect of the Ag component, which was found to be closely related to the size and loading amount of Ag. The rapid silver method is effective at curbing the size of Ag, so photocatalytic activity can be improved. Diverse organic chemical products were detected, including mainly methane and methanol as well as a small amount of C2 and C3 species such as acetaldehyde and acetone. Possible photocatalytic mechanisms were proposed. This artificial photosynthesis process may give a prosperous route to the removal of CO2 while simultaneously converting CO2 to valuable fuels based on highly

  14. What and how should we teach so as to prepare the next generation of hydrologists for a rapidly changing world?

    Science.gov (United States)

    Savenije, Hubert

    2010-05-01

    In principle, we can learn from history and from historical data how a hydrological system behaved in the past. But what can we learn about new situations? Can we predict with confidence how our natural systems will function under changing boundary conditions? If the answer to this question is negative, then how can we prepare future generation to deal with these issues? I think that we have to focus on understanding physical processes at scales where they demonstrate organised behaviour, or - to put it in other words - at scales were patterns emerge. In recent years we have seen how the reductionist approach is incapable of predicting uncertain situations. Instead, we will have to focus on recognising dominant behaviour and on modelling this behaviour in the simplest terms possible. This brings us to the question how we can identify and conceptualise dominant and secondary behaviour in connection to a changing environment and subject to changed forcing. What does this mean for education? I think we have to teach basic physics and basic physical principles and processes at plot scale, but also at the scale of hill slopes, watersheds and river basins. This has to be strongly intertwined with field work. Only in the field can students recognise the processes and the thresholds that need to be passed for certain processes to become active. Next, students should learn how to conceptualise the hydrological world within a rejectionist framework of hypothesis testing; how to develop and use diagnostics to test hypothesis; and, more importantly, how to develop and use creativity to generate new hypotheses, in dialogue with the experimentalist and field hydrologist. Finally there are issues related to process. Learning should consist largely of learning by doing: literature studies, field work, experiments, colloquia, exercises, presentations, paper writing, discussion groups. Lecturing should not be more than 50% of the contact time and should be interactive and meant to

  15. Rapid mixing chemical oxidative polymerization: an easy route to prepare PANI coated small-diameter CNTs/PANI nanofibres composite thin film

    Indian Academy of Sciences (India)

    G Venkata Ramana; Balaji Padya; Vadali V S S Srikanth; P K Jain

    2014-05-01

    Composite thin film containing polyaniline (PANI) coated small diameter carbon nanotubes (SDCNTs)/PANI nanofibres (NFs) has been prepared using an easy in situ rapid mixing chemical oxidative polymerization method. SDCNTs thin film was obtained using thermal chemical vapour deposition method in a separate experiment, whilst PANI NFs are formed in situ during the synthesis of composite. In the composite, PANI coated SDCNTs are uniformly distributed among PANI NFs. The presence of SDCNTs during the composite synthesis does not influence the nucleation and growth of PANI NFs. Raman analysis shows a good interaction between PANI and SDCNTs. Room temperature d.c. electrical sheet resistance of SDCNTs/PANI NFs composite thin film surface is three orders lesser than that of PANI NFs thin film (PANI NFs have the same morphology as in the composite) synthesized using the same method but without the presence of SDCNTs.

  16. Rapid specimen preparation to improve the throughput of electron microscopic volume imaging for three-dimensional analyses of subcellular ultrastructures with serial block-face scanning electron microscopy.

    Science.gov (United States)

    Thai, Truc Quynh; Nguyen, Huy Bang; Saitoh, Sei; Wu, Bao; Saitoh, Yurika; Shimo, Satoshi; Elewa, Yaser Hosny Ali; Ichii, Osamu; Kon, Yasuhiro; Takaki, Takashi; Joh, Kensuke; Ohno, Nobuhiko

    2016-09-01

    Serial block-face imaging using scanning electron microscopy enables rapid observations of three-dimensional ultrastructures in a large volume of biological specimens. However, such imaging usually requires days for sample preparation to reduce charging and increase image contrast. In this study, we report a rapid procedure to acquire serial electron microscopic images within 1 day for three-dimensional analyses of subcellular ultrastructures. This procedure is based on serial block-face with two major modifications, including a new sample treatment device and direct polymerization on the rivets, to reduce the time and workload needed. The modified procedure without uranyl acetate can produce tens of embedded samples observable under serial block-face scanning electron microscopy within 1 day. The serial images obtained are similar to the block-face images acquired by common procedures, and are applicable to three-dimensional reconstructions at a subcellular resolution. Using this approach, regional immune deposits and the double contour or heterogeneous thinning of basement membranes were observed in the glomerular capillary loops of an autoimmune nephropathy model. These modifications provide options to improve the throughput of three-dimensional electron microscopic examinations, and will ultimately be beneficial for the wider application of volume imaging in life science and clinical medicine.

  17. Rapid microwave-assisted sol-gel preparation of Pd-substituted LnFeO3 (Ln = Y, La): phase formation and catalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Misch, Lauren M.; Birkel, Alexander; Figg, C. Adrian; Fors, Brett P.; Hawker, Craig J.; Stucky, Galen D.; Seshadri, Ram [UCSB

    2014-02-13

    We present a rapid microwave-assisted sol–gel approach to Pd-substituted LnFeO3 (Ln = Y, La) for applications in C–C coupling reactions. These materials could be prepared in household microwave ovens in less than 15 minutes of reaction time with the final materials displaying well-defined structure and morphology. Phase evolution was studied using time-dependent microwave heatings and then compared with the results obtained from thermogravimetric analyses. Materials were confirmed to be phase pure by laboratory and synchrotron X-ray diffraction. Substituted Pd is ionic as shown by the binding energy shift from X-ray photoelectron spectroscopy. The short heating periods required for phase purity allow these materials less time for sintering as compared to conventional solid state preparation methods, making relatively high surface areas achievable. These materials have been successfully used as catalyst precursor materials for C–C coupling reactions in which the active species is Pd0. Pd-substituted LnFeO3 (Ln = Y, La) provides Pd0 in solution which can be complexed by the ligand SPhos, allowing for aryl chloride coupling.

  18. A Rapid Method of Preparing DNA Template of Filamentous Fungi for PCR Amplification%丝状真菌PCR模板DNA的快速制备方法

    Institute of Scientific and Technical Information of China (English)

    罗中钦; 程琳; 张茜; 陈国华

    2015-01-01

    以尖孢镰刀菌(Fusarium oxysporum)为材料,旨为建立沸水浴获得PCR模板DNA的新方法。取少量真菌菌丝置于一定体积50 mmol/L NaOH溶液中沸水浴10 min,再加入1/10体积1 mol/L Tris-HCl(pH8.0)缓冲液,12000 r/min离心后,上清用作PCR的DNA模板。结果显示,该方法扩增效率高,扩增条带清晰,且Taq酶适应性强,适合快速制备丝状真菌的模板DNA。该方法经济、简单、快速、安全高效,可用于丝状真菌转化子的高通量筛选和菌株的快速鉴定。%This work aims to establish a novel method of extracting DNA template of filamentous fungi for PCR amplification with boiling-water bath and Fusarium oxysporum as raw material. The procedures of this method are as the following:exposing the fungal mycelia in certain volume of 50 mmol/L NaOH solution under boiling water bath, adding 1/10 volume of 1mol/L Tris-HCl(pH8.0)buffer, centrifuging it at 12 000 r/min for 10 min, and using the supernatant as the DNA template for PCR amplification. Results demonstrated that the efficiency of PCR amplification with the DNA template prepared by the method was high, the amplified bands were clear, and adaptability to various Taq DNA polymerases was strong;This indicated that the method was suitable for the preparation of DNA template of filamentous fungi. Conclusively, this method is economic, simple, rapid, safe and high-efficient, and can be utilized for high-throughput screening of filamentous fungal transformants and rapid identification of isolated strains.

  19. Preparation of molecularly imprinted polymers on the surface of magnetic carbon nanotubes with a pseudo template for rapid simultaneous extraction of four fluoroquinolones in egg samples.

    Science.gov (United States)

    Xiao, Deli; Dramou, Pierre; Xiong, Nanqian; He, Hua; Yuan, Danhua; Dai, Hao; Li, Hui; He, Xiaomei; Peng, Jun; Li, Nan

    2013-06-07

    Fluoroquinolones (FQs) have emerged as one of the most important class of antibiotics. Due to their low concentration in bio-matrix samples which contain a lot of interfering substances, the efficient solid phase extraction and accurate determination of FQs remain a challenge. In this paper, a new strategy for the isolation and enrichment of FQs from egg samples was obtained by molecularly imprinted polymers on the surface of magnetic carbon nanotubes (MCNTs@MIP), which not only can be collected and separated rapidly by an external magnetic field, but also have a high specific surface area, outstanding mechanical properties and specific recognition for FQs. MCNTs@MIP were prepared using ofloxacin as a pseudo template, methacrylic acid as a functional monomer, and ethylene glycol dimethacrylate as a cross-linker. The characteristics of the MCNTs@MIP were assessed by transmission electron microscopy (TEM), multipoint Brunauer-Emmett-Teller (BET) analysis, vibrating sample magnetometry (VSM), X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. The results of the adsorption experiments not only demonstrated rapid dynamic adsorption but also showed a high selectivity toward FQs. An extraction method using MCNTs@MIP coupled with high performance liquid chromatography (HPLC) was developed for the determination of four FQs in egg samples. The recovery of four FQs ranged from 95.2% ± 3.2% to 100.7% ± 3.1% and the detection limits ranged from 0.25-0.40 ng g(-1). The results demonstrate that the proposed method based on pseudo template MCNTs@MIP is a promising approach for the preconcentration, purification, and simultaneous analysis of four FQs in bio-matrix samples.

  20. 取向结构和梯度分布医用材料的制备及应用%Preparation and Applications of Ordered and Gradient Scaffolds in Regenerative Medicine

    Institute of Scientific and Technical Information of China (English)

    邢东明; 马列; 高长有

    2011-01-01

    The tissue loss or organ failure,resulting from trauma or diseases,is a major concern in human healthcare.The recent development of regenerative medicine by combing the cells and degradable scaffolds offers a unique pathway to recreate tissues and organs with high bioactivity and biomimetic structures.This article reviews the state-of-art of the ordered and gradient scaffolds in terms of their preparation methods and biological performance.In contrast with the homogeneous counterpart,the ordered scaffolds facilitate delivery of nutrients and metabolites,and can guide cell growth,distribution and new tissue formation in vitro,leading to construction of 3D-engineered tissues with ordered cells and extracellular matrix.On the other hand,the gradient cues(e.g.physical,chemical and biological properties) incorporated into the 3D scaffolds can create a microenvironment governing the cell behaviors such as migration rate and direction as well as differentiation,and thereby guiding the tissue regeneration.The methods of phase separation,electrospinning,injection and centrifugation are usually employed to prepare the ordered and gradient 2D substrate and 3D scaffolds.The biological performance of these scaffolds is discussed.Wish such a structure mimicking the native tissue-like environment,the scaffolds are expected to show exceptional advantages in regeneration of tissues and organs of better functions and structures.%组织器官缺损或功能损失是人类健康所面临的重大危害,具有特定结构和组成的再生医学材料是实现组织再生与修复的关键和物质基础。本文对具有取向结构和梯度分布的再生医学材料的制备方法及其生物学性能进行了综述。与传统的再生医学材料相比,取向结构使得细胞在支架中呈取向分布和生长,有利于营养物质及代谢产物的传递,可用于构建具有取向结构的三维组织。具有物理性能、化学组成、生物因子梯度分布的再生

  1. Rapid preparative separation of six bioactive compounds from Gentiana crassicaulis Duthie ex Burk. using microwave-assisted extraction coupled with high-speed counter-current chromatography.

    Science.gov (United States)

    Liang, Jinru; Ito, Yoichiro; Zhang, Xinxin; He, Jiao; Sun, Wenji

    2013-12-01

    A rapid method combining microwave-assisted extraction (MAE) and high-speed counter-current chromatography (HSCCC) was applied for preparative separation of six bioactive compounds including loganic acid (I), isoorientin-4'-O-glucoside (II), 6'-O-β-d-glucopyranosyl gentiopicroside (III), swertiamarin (IV), gentiopicroside (V), sweroside (VI) from traditional Tibetan medicine Gentiana crassicaulis Duthie ex Burk. MAE parameters were predicted by central composite design response surface methodology. That is, 5.0 g dried roots of G. crassicaulis were extracted with 50 mL 57.5% aqueous ethanol under 630 W for 3.39 min. The extract (gentian total glycosides) was separated by HSCCC with n-butanol/ethyl acetate/methanol/1% acetic acid water (7.5:0.5:0.5:3.5, v/v/v/v) using upper phase mobile in tail-to-head elution mode. 16.3, 8.8, 12., 25.1, 40.7, and 21.8 mg of compounds I-VI were obtained with high purities in one run from 500 mg of original sample. The purities and identities of separated components were confirmed using HPLC with photo diode array detection and quadrupole TOF-MS and NMR spectroscopy. The study reveals that response surface methodology is convenient and highly predictive for optimizing extraction process, MAE coupled with HSCCC could be an expeditious method for extraction and separation of phytochemicals from ethnomedicine.

  2. Preparation of multilocation reduction-sensitive core crosslinked folate-PEG-coated micelles for rapid release of doxorubicin and tariquidar to overcome drug resistance

    Science.gov (United States)

    Yi, Xiaoqing; Zhao, Dan; Zhang, Quan; Xu, Jiaqi; Yuan, Gongdao; Zhuo, Renxi; Li, Feng

    2017-02-01

    Herein, we prepared folate-targeting core crosslinked polymeric micelles (CCL/FA) containing multiple disulfide bonds located at the interface and core of the micelles to co-deliver doxorubicin (DOX) and the P-glycoprotein (P-gp) inhibitor tariquidar (TQR) for reversing drug resistance. The stability and redox-responsive behavior of the CCL/FA micelles was evaluated through the changes in morphology, molecular weight and hydrodynamic size. On the one hand, the micelles possessed good stability, which led to the suppression of drug release from the CCL micelles in the physiological environment. On the other hand, under reductive conditions, the CCL micelles collapsed rapidly and accelerated drug release markedly. In vitro cytotoxicity measurements, combined with confocal laser scanning microscopy (CLSM) and flow cytometry, confirmed that the dual-drug-loaded micelles exhibited obviously higher cytotoxicity to MCF-7/ADR-resistant cells than free DOX · HCl, single-drug loaded CCL micelles and nontargeted CCL micelles. The results imply that co-delivering DOX and TQR by CCL/FA micelles may be a promising way of overcoming multidrug resistance in tumor treatments.

  3. Honeycomb-like NiCo2S4 nanosheets prepared by rapid electrodeposition as a counter electrode for dye-sensitized solar cells

    Science.gov (United States)

    Yin, Jie; Wang, Yuqiao; Meng, Wenfei; Zhou, Tianyue; Li, Baosong; Wei, Tao; Sun, Yueming

    2017-08-01

    Honeycomb-like nickel cobalt sulfide (NiCo2S4) nanosheets were directly deposited on fluorine-doped tin oxide substrate by a rapid voltammetric deposition method. The method was also controllable and feasible for preparing NiCo2S4 on flexible Ti foil without any heating processes. Compared with Pt, CoS and NiS, NiCo2S4 exhibited low charge-transfer resistances and excellent electrocatalytic activity for {{{{I}}}3}- reduction, acting as a counter electrode for a dye-sensitized solar cell. The NiCo2S4-based solar cell showed higher power conversion efficiency (7.44%) than that of Pt-based solar cell (7.09%) under simulated illumination (AM 1.5 G, 100 mW cm-2). The device based on the flexible NiCo2S4/Ti foil achieved a power conversion efficiency of 5.28% under the above illumination conditions. This work can be extended to flexible and wearable technologies due to its facile technique.

  4. Electrical Characteristics and Preparation of (Ba0.5Sr0.5)TiO3 Films by Spray Pyrolysis and Rapid Thermal Annealing

    Science.gov (United States)

    Koo, Horng-Show; Chen, Mi; Ku, Hong-Kou; Kawai, Tomoji

    2007-04-01

    Functional films of (Ba0.5Sr0.5)TiO3 on Pt (1000 Å)/Ti (100 Å)/SiO2 (2000 Å)/Si substrates are prepared by spray pyrolysis and subsequently rapid thermal annealing. Barium nitrate, strontium nitrate and titanium isopropoxide are used as starting materials with ethylene glycol as solvent. For (Ba0.5Sr0.5)TiO3 functional thin film, thermal characteristics of the precursor powder scratched from as-sprayed films show a remarkable peak around 300-400 °C and 57.7% weight loss up to 1000 °C. The as-sprayed precursor film with coffee-like color and amorphous-like phase is transformed into the resultant film with white, crystalline perovskite phase and characteristic peaks (110) and (100). The resultant films show correspondent increases of dielectric constant, leakage current and dissipation factor with increasing annealing temperatures. The dielectric constant is 264 and tangent loss is 0.21 in the resultant films annealed at 750 °C for 5 min while leakage current density is 1.5× 10-6 A/cm2 in the film annealed at 550 °C for 5 min.

  5. A conveniently prepared and hypersensitized small molecular fluorescent probe: Rapidly detecting free zinc ion in HepG2 cells and Arabidopsis.

    Science.gov (United States)

    Gan, Xiaoping; Sun, Ping; Li, Hong; Tian, Xiaohe; Zhang, Baowei; Wu, Jieying; Tian, Yupeng; Zhou, Hongping

    2016-12-15

    In this paper, we reported a conveniently prepared fluorescent probe for zinc ions detection, which constructed by the condensation reaction between p-(benzothiazolyl)aniline with 4, 4- diethylaminesalicylaldehyde. The sensing ability of the probe toward zinc ions in vitro was tested by a series of UV-Vis and fluorescence spectroscopy studies, which showed that the probe possessed high sensitivity with a detection limit of 5.8nM and a rapid response time of 10s. We also carried out fluorescent bio-imaging of the probe for zinc ions in human liver hepatocellular carcinoma cells (HepG2), which showed that the probe could be utilized to detect the intracellular endogenous zinc ions visually without introducing external zinc sources. Meanwhile, co-staining experiment with organelle selective trackers was performed to illustrate that the probe could locate at endoplasmic reticulum. Finally, we successfully used it as a zinc ion developer in plant tissue, which clearly demonstrated the distribution of zinc ions in the growth stage of plant tissue. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Submarine navigation based on gravity gradient-terrain matching

    Science.gov (United States)

    Xiong, Ling; Ma, Jie; Zhang, Li; Tian, Jin-Wen; Liu, Jian

    2007-11-01

    Based on the geophysics technology, a gravity gradient-terrain matching submarine navigation approach is proposed in this paper. The submarine's current position obtained by matching the measured gravity gradient data to the prepared gravity gradient reference map is used to correct the inertial navigation system's accumulated error. Although the precision gradiometer is in use, there is no world-wide gravity gradient map. The ocean's gravity gradient data is even scarce. Therefore, a gravity gradient matching navigation system directly utilizing the gravity gradient reference map can't be realized. With the sensitivity of gravity gradient to terrain, the gravity gradient reference map can be computed from the local terrain elevation data and the preparing approach of the gravity gradient map is proposed in detail in the paper. Since the seabed terrain elevation map, especially highly accurate offing terrain elevation map has been pre-surveyed, the location can be actualized through matching the real-time measured gravity gradient data to the prepared gravity gradient reference map. Simulations show that the submarine navigation approach on gravity gradient-terrain matching is feasible and can be put into practice.

  7. STUDY ON A HYDROPHOBIC-HYDROPHILIC GRADIENT ROD

    Institute of Scientific and Technical Information of China (English)

    Jun Ma; Bai-yu Li; Hai-yun Liu; Zhi-min Zheng; Jian Xu

    2004-01-01

    A hydrophobic-hydrophilic gradient rod with a length of 40 mm and a diameter of 3 mm was prepared by heating a polymethylsilsesquioxane rod in a cylindrical stove with temperature gradient. The rod was thus pyrolyzed under a temperature gradient condition. The organic end of the gradient rod appears hydrophobic with a contact angle of 109.9° while the other end is hydrophilic with a contact angle of 62.4°. The gradient chemical structure and the gradient microstructure along the rod were characterized by FTIR and SEM, respectively.

  8. Rapid Preparation Process of Silver Nanoparticles by Bioreduction and Their Characterizations%生物还原快速制备纳米银颗粒及其表征

    Institute of Scientific and Technical Information of China (English)

    傅谋兴; 李清彪; 孙道华; 卢英华; 何宁; 邓旭; 王惠璇; 黄加乐

    2006-01-01

    Bioreduction as a novel nanoparticle synthesizing technology attracts increasing attention. Dried cells of the bacterium Aeromonas sp. SH10 rapidly reduced [Ag(NH3)2]+ to Ag0 in the solution into which some amount of OH- was introduced. The surface plasmon resonance centered at 425 nm on the UV-vis spectra and five broad Bragg reflections on the XRD pattern showed that stable silver nanoparticles were formed during the bioreduction process. TEM and SEM observations suggested that the silver nanoparticles were uniform in size and well dispersed on the cells and in the solution. Therefore, silver nanoparticles could be prepared rapidly by this bioreduction technology.

  9. Application of an efficient strategy based on liquid-liquid extraction, high-speed counter-current chromatography, and preparative HPLC for the rapid enrichment, separation, and purification of four anthraquinones from Rheum tanguticum.

    Science.gov (United States)

    Chen, Tao; Liu, Yongling; Zou, Denglang; Chen, Chen; You, Jinmao; Zhou, Guoying; Sun, Jing; Li, Yulin

    2014-01-01

    This study presents an efficient strategy based on liquid-liquid extraction, high-speed counter-current chromatography, and preparative HPLC for the rapid enrichment, separation, and purification of four anthraquinones from Rheum tanguticum. A new solvent system composed of petroleum ether/ethyl acetate/water (4:2:1, v/v/v) was developed for the liquid-liquid extraction of the crude extract from R. tanguticum. As a result, emodin, aloe-emodin, physcion, and chrysophanol were greatly enriched in the organic layer. In addition, an efficient method was successfully established to separate and purify the above anthraquinones by high-speed counter-current chromatography and preparative HPLC. This study supplies a new alternative method for the rapid enrichment, separation, and purification of emodin, aloe-emodin, physcione, and chrysophanol. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Gradients are shaping up.

    Science.gov (United States)

    Bollenbach, Tobias; Heisenberg, Carl-Philipp

    2015-04-23

    In animal embryos, morphogen gradients determine tissue patterning and morphogenesis. Shyer et al. provide evidence that, during vertebrate gut formation, tissue folding generates graded activity of signals required for subsequent steps of gut growth and differentiation, thereby revealing an intriguing link between tissue morphogenesis and morphogen gradient formation.

  11. Fast Distributed Gradient Methods

    CERN Document Server

    Jakovetic, Dusan; Moura, Jose M F

    2011-01-01

    The paper proposes new fast distributed optimization gradient methods and proves convergence to the exact solution at rate O(\\log k/k), much faster than existing distributed optimization (sub)gradient methods with convergence O(1/\\sqrt{k}), while incurring practically no additional communication nor computation cost overhead per iteration. We achieve this for convex (with at least one strongly convex,) coercive, three times differentiable and with Lipschitz continuous first derivative (private) cost functions. Our work recovers for distributed optimization similar convergence rate gains obtained by centralized Nesterov gradient and fast iterative shrinkage-thresholding algorithm (FISTA) methods over ordinary centralized gradient methods. We also present a constant step size distributed fast gradient algorithm for composite non-differentiable costs. A simulation illustrates the effectiveness of our distributed methods.

  12. Detection of Rifampin Resistance in Mycobacterium tuberculosis by Double Gradient-Denaturing Gradient Gel Electrophoresis

    Science.gov (United States)

    Scarpellini, Paolo; Braglia, Sergio; Carrera, Paola; Cedri, Maura; Cichero, Paola; Colombo, Alessia; Crucianelli, Rosella; Gori, Andrea; Ferrari, Maurizio; Lazzarin, Adriano

    1999-01-01

    We applied double gradient-denaturing gradient gel electrophoresis (DG-DGGE) for the rapid detection of rifampin (RMP) resistance from rpoB PCR products of Mycobacterium tuberculosis isolates and clinical samples. The results of this method were fully concordant with those of DNA sequencing and susceptibility testing analyses. DG-DGGE is a valid alternative to the other methods of detecting mutations for predicting RMP resistance. PMID:10508043

  13. Preparation of vinorelbine bitartrate long-circulating liposomes by ionophore A23187-mediated pH gradient method%离子载体A23187介导pH梯度法制备重酒石酸长春瑞滨长循环脂质体

    Institute of Scientific and Technical Information of China (English)

    杨光丽; 张冰; 赵利刚; 张勇; 王栋海; 尹青; 杨清敏

    2012-01-01

    目的:采用A23187制备重酒石酸长春瑞滨长循环脂质体,优化了处方工艺,并考察了含量、包封率、药脂比和体外释放等检测指标.方法:采用A23187介导的pH梯度法制备了重酒石酸长春瑞滨脂质体;用HPLC法检测了脂质体中重酒石酸长春瑞滨的含量和脂质(HSPC)的含量,考察了药脂比;采用阳离子交换树脂分离脂质体和游离药物,HPLC法检测包封率;以4 mmol· L- NH4Cl-PBS(pH 7.4)为体外释放介质考察了脂质体的体外释放行为.结果:重酒石酸长春瑞滨脂质体包封率为96.1%,药脂比为1:5(w/w);高药脂比有利于延长药物体外释放的时间.结论:采用A23187介导的pH梯度法制备重酒石酸长春瑞滨脂质体工艺可行、载药量大、包封率高;所建立体外释放的检测方法快速、准确.%Objective: To prepare vinorelbine bitartrate long-circulating liposomes and optimize the formulation and process parameters, and to investigate vinorelbine contents, entrapment efficiency, drug-to-lipid ratio, in vitro release rate of the liposomal vinorelbine. Methods: Vinorelbine bitartrate liposomes were prepared in response to a transmembrane pH gradient that was generated by the use of ionophore A23187. Drug-to-lipid ratio was calculated by vinorelbine bitartrate content and HSPC content that were determined by HPLC. Free vinorelbine and liposomal vinorelbine were separated by cation exchange resin ultraviolet, and the encapsulation efficiency was determined by HPLC. The in vitro release behavior was investigated in 4 mmol·L-1 NH4C1-PBS ( pH 7.4). Results: The encapsulation efficiency and drug-to-lipid ratio of the vinorelbine liposomes were 96. 1% and 1:5 (mass ratio) , respectively. The higher drug-to-lipid ratio reduced the in vitro release rate of vinorelbine from liposomes. Conclusion: The ionophore A23187-loading technique is feasible for preparing vinorelbine bitartrate long-circulating liposomes. The drug loading and

  14. A lab-on-a-chip system with integrated sample preparation and loop-mediated isothermal amplification for rapid and quantitative detection of Salmonella spp. in food samples

    DEFF Research Database (Denmark)

    Sun, Yi; Than Linh, Quyen; Hung, Tran Quang;

    2015-01-01

    amplification (LAMP) for rapid and quantitative detection of Salmonella spp. in food samples. The whole diagnostic procedures including DNA isolation, isothermal amplification, and real-time detection were accomplished in a single chamber. Up to eight samples could be handled simultaneously and the system...... was capable to detect Salmonella at concentration of 50 cells per test within 40 min. The simple design, together with high level of integration, isothermal amplification, and quantitative analysis of multiple samples in short time will greatly enhance the practical applicability of the LOC system for rapid...

  15. Preparation of a Rapidly Forming Poly(ferrocenylsilane)-Poly(ethylene glycol)-based Hydrogel by a Thiol–Michael Addition Click Reaction

    NARCIS (Netherlands)

    Sui, Xiaofeng; van Ingen, Lennard; Hempenius, Mark A.; Vancso, Gyula J.

    2010-01-01

    The synthesis of a rapidly forming redox responsive poly(ferrocenylsilane)-poly(ethylene glycol) (PFS-PEG)-based hydrogel is described, achieved by a thiol-Michael addition click reaction. PFS bearing acrylate side groups (PFS-acryl) was synthesized by side group modification of

  16. Assessment of Preparation of Samples Under the Field Conditions and a Portable Real-Time RT-PCR Assay for the Rapid On-Site Detection of Newcastle Disease Virus.

    Science.gov (United States)

    Liu, L; Benyeda, Z; Zohari, S; Yacoub, A; Isaksson, M; Leijon, M; LeBlanc, N; Benyeda, J; Belák, S

    2016-04-01

    Newcastle disease virus (NDV), also known as virulent forms of avian paramyxovirus serotype 1 (AMPV-1), is the causative agent of Newcastle disease affecting many species of birds and causing heavy losses to the poultry industry worldwide. Early, rapid and sensitive detection of the viruses or the viral nucleic acids is very important for disease diagnosis and control. This study aimed to evaluate sample preparation under field conditions and the application of a real-time RT-PCR method in the portable T-COR4 platform for the rapid, on-site detection of NDV on a farm. In the laboratory setting, the portable real-time RT-PCR assay had a similar performance compared with that obtained with a larger, stationary Rotor Gene real-time thermocycler. In the field conditions, viral nucleic acids were manually extracted just outside of animal units with minimal equipment and real-time RT-PCR detection was performed with the portable thermocycler T-COR4 placed in a nearby room. The portable assay at the farm detected viral RNA in 15 samples and reached an agreement of 83% (39/47) when the same RNA preparations were tested in the Rotor Gene thermocycler under the laboratory setting. The results demonstrated the feasibility of performing field detection but also the need to improve and further simplify sample preparation procedures.

  17. Laser textured surface gradients

    Science.gov (United States)

    Ta, Van Duong; Dunn, Andrew; Wasley, Thomas J.; Li, Ji; Kay, Robert W.; Stringer, Jonathan; Smith, Patrick J.; Esenturk, Emre; Connaughton, Colm; Shephard, Jonathan D.

    2016-05-01

    This work demonstrates a novel technique for fabricating surfaces with roughness and wettability gradients and their subsequent applications for chemical sensors. Surface roughness gradients on brass sheets are obtained directly by nanosecond laser texturing. When these structured surfaces are exposed to air, their wettability decreases with time (up to 20 days) achieving both spatial and temporal wettability gradients. The surfaces are responsive to organic solvents. Contact angles of a series of dilute isopropanol solutions decay exponentially with concentration. In particular, a fall of 132° in contact angle is observed on a surface gradient, one order of magnitude higher than the 14° observed for the unprocessed surface, when the isopropanol concentration increased from 0 to 15.6 wt%. As the wettability changes gradually over the surface, contact angle also changes correspondingly. This effect offers multi-sensitivity at different zones on the surface and is useful for accurate measurement of chemical concentration.

  18. Second gradient poromechanics

    CERN Document Server

    Sciarra, Giulio; Coussy, Olivier

    2010-01-01

    Second gradient theories have been developed in mechanics for treating different phenomena as capillarity in fluids, plasticity and friction in granular materials or shear band deformations. Here, there is an attempt of formulating a second gradient Biot like model for porous materials. In particular the interest is focused in describing the local dilatant behaviour of a porous material induced by pore opening elastic and capillary interaction phenomena among neighbouring pores and related micro-filtration phenomena by means of a continuum microstructured model. The main idea is to extend the classical macroscopic Biot model by including in the description second gradient effects. This is done by assuming that the surface contribution to the external work rate functional depends on the normal derivative of the velocity or equivalently assuming that the strain work rate functional depends on the porosity and strain gradients. According to classical thermodynamics suitable restrictions for stresses and second g...

  19. Synthesis and characterization of erbium-doped SiO{sub 2}-TiO{sub 2} thin films prepared by sol-gel and dip-coating techniques onto commercial glass substrates as a route for obtaining active GRadient-INdex materials

    Energy Technology Data Exchange (ETDEWEB)

    Gómez-Varela, Ana I. [Microoptics and GRIN Optics Group, Department of Applied Physics, Faculty of Optics and Optometry and Faculty of Physics, Universidade de Santiago de Compostela, Campus Vida s/n, Santiago de Compostela E-15782 (Spain); Castro, Yolanda, E-mail: castro@icv.csic.es [Instituto de Cerámica y Vidrio (CSIC), Kelsen 5, Campus de Cantoblanco, Madrid 28049 (Spain); Durán, Alicia [Instituto de Cerámica y Vidrio (CSIC), Kelsen 5, Campus de Cantoblanco, Madrid 28049 (Spain); De Beule, Pieter A.A. [Applied Nano-Optics Laboratory, International Iberian Nanotechnology Laboratory, Braga 4715-330 (Portugal); Flores-Arias, María T. [Microoptics and GRIN Optics Group, Department of Applied Physics, Faculty of Optics and Optometry and Faculty of Physics, Universidade de Santiago de Compostela, Campus Vida s/n, Santiago de Compostela E-15782 (Spain); Bao-Varela, Carmen, E-mail: carmen.bao@usc.es [Microoptics and GRIN Optics Group, Department of Applied Physics, Faculty of Optics and Optometry and Faculty of Physics, Universidade de Santiago de Compostela, Campus Vida s/n, Santiago de Compostela E-15782 (Spain)

    2015-05-29

    In this work, SiO{sub 2}-TiO{sub 2} films doped with erbium were prepared by dip-coating sol-gel process onto commercial glass substrates. The surface morphology of the films was characterized using atomic force microscopy, while thickness, refractive index, extinction coefficient and porosity of the films were determined by ellipsometric measurements in a wavelength region of 400-1000 nm. Optical constants and porosity were found to vary with erbium concentration. The proof of principle presented in this paper is applicable to systems of different nature by tailoring the sol-gel precursors in such a way that active GRadient-INdex media described by a complex, parabolic-like refractive index distribution for beam shaping purposes is obtained. - Highlights: • Sol-gel route for preparation of active GRadient-INdex materials is proposed. • SiO{sub 2}-TiO{sub 2} films doped with erbium were prepared by dipping onto commercial glasses. • Morphological and optical characterization of the samples was performed. • Optical constants and porosity were found to vary with erbium concentration. • Refractive index diminishes with dopant content; the contrary occurs for porosity.

  20. Allogeneic Platelet Releasate Preparations Derived via a Novel Rapid Thrombin Activation Process Promote Rapid Growth and Increased BMP-2 and BMP-4 Expression in Human Adipose-Derived Stem Cells.

    Science.gov (United States)

    McLaughlin, Michael; Gagnet, Paul; Cunningham, Elizabeth; Yeager, Randi; D'Amico, Michael; Guski, Katie; Scarpone, Michael; Kuebler, Daniel

    2016-01-01

    The administration of human adipose-derived stem cells (ASCs) represents a promising regenerative therapy for the treatment of orthopedic injuries. While ASCs can be easily isolated from liposuction-derived adipose tissue, most clinical applications will likely require in vitro culture expansion of these cells using nonxenogeneic components. In this study, platelet releasate was generated using a novel rapid thrombin activation method (tPR). ASCs grown in media supplemented with tPR proliferated much faster than ASCs grown in media supplemented with 10% fetal bovine serum. The cells also retained the ability to differentiate along chondrogenic, adipogenic, and osteogenic lineages. The tPR cultured ASCs displayed elevated expression of BMP-4 (5.7 ± 0.97-fold increase) and BMP-2 (4.7 ± 1.3-fold increase) and decreased expression of PDGF-B (4.0 ± 1.4-fold decrease) and FGF-2 (33 ± 9.0-fold decrease). No significant changes in expression were seen with TGF-β and VEGF. This pattern of gene expression was consistent across different allogeneic tPR samples and different ASC lines. The use of allogeneic rapidly activated tPR to culture ASCs is associated with both an increased cell yield and a defined gene expression profile making it an attractive option for cell expansion prior to cell-based therapy for orthopedic applications.

  1. Allogeneic Platelet Releasate Preparations Derived via a Novel Rapid Thrombin Activation Process Promote Rapid Growth and Increased BMP-2 and BMP-4 Expression in Human Adipose-Derived Stem Cells

    Directory of Open Access Journals (Sweden)

    Michael McLaughlin

    2016-01-01

    Full Text Available The administration of human adipose-derived stem cells (ASCs represents a promising regenerative therapy for the treatment of orthopedic injuries. While ASCs can be easily isolated from liposuction-derived adipose tissue, most clinical applications will likely require in vitro culture expansion of these cells using nonxenogeneic components. In this study, platelet releasate was generated using a novel rapid thrombin activation method (tPR. ASCs grown in media supplemented with tPR proliferated much faster than ASCs grown in media supplemented with 10% fetal bovine serum. The cells also retained the ability to differentiate along chondrogenic, adipogenic, and osteogenic lineages. The tPR cultured ASCs displayed elevated expression of BMP-4 (5.7 ± 0.97-fold increase and BMP-2 (4.7 ± 1.3-fold increase and decreased expression of PDGF-B (4.0 ± 1.4-fold decrease and FGF-2 (33 ± 9.0-fold decrease. No significant changes in expression were seen with TGF-β and VEGF. This pattern of gene expression was consistent across different allogeneic tPR samples and different ASC lines. The use of allogeneic rapidly activated tPR to culture ASCs is associated with both an increased cell yield and a defined gene expression profile making it an attractive option for cell expansion prior to cell-based therapy for orthopedic applications.

  2. Rapid preparation of (3R,4S,5R) polyhydroxylated pyrrolidine-based libraries to discover a pharmacological chaperone for treatment of Fabry disease.

    Science.gov (United States)

    Cheng, Wei-Chieh; Wang, Jen-Hon; Yun, Wen-Yi; Li, Huang-Yi; Hu, Jia-Ming

    2017-01-27

    The rapid discovery of a pharmacological chaperone toward human α-Gal A for the treatment of Fabry disease is described. Two polyhydroxylated pyrrolidines with the (3R,4S,5R) configuration pattern underwent rapid substituent diversity by conjugating the primary aminomethyl moiety of each with a variety of carboxylic acids to generate two libraries (2 × 60 members). Our bioevaluation results showed one member with the (2R,3R,4S,5R) configuration pattern and bearing a 5-cyclohexylpentanoyl group as a substituent moiety possessed sufficient chaperoning capability to rescue α-Gal A activity in the lymphocyte of the N215S Fabry patient-derived cell line and other α-Gal A mutants in COS7 cells.

  3. PREPARATION AND ACTIVATION OF RAPIDLY SOLIDIFIED Ni-Zr-Al AMORPHOUS ALLOY FOR CATALYTIC PURPOSE%快速凝固Ni-Zr-Al非晶态催化合金的制备与活化处理

    Institute of Scientific and Technical Information of China (English)

    张国胜; 张海峰; 沈宁福

    1999-01-01

    @@ As new catalytic materials, amorphous alloys have attracted much attention since 1980s. Rapid solidification is one of the main techniques to prepare amorphous alloys.However, as-cast rapidly solidified alloys usually can not be directly used as the catalyst for their poor surface area, oxide film on their surface, etc. Therefore, activation pretreatment must be carried out. Recently, leaching aluminum has been attempted to activate rapidly solidified amorphous catalytic alloys containing aluminum. In order to carry out such an activation pretreatment, the Al-rich amorphous precursor alloys must be obtained first, in which the content of active component must be sufficiently high so that the catalytic activity of the activated catalyst can be attained. On the other hand, the chemical composition of the precursor must approach eutectic point or contribute to the range of low liquidus temperature so that the glass transition can be easily achieved according to the solidification theory[1]. So far Al-based alloys which meet the dual confinement have not been found yet. For Ni-Al and Cu-Al systems,only the microcrystalline alloys can be obtained through rapid solidification[2,3].In the present study, glass formation was achieved by introducing promotion elements in Ni-Al system precursor alloys.

  4. High Gradient Accelerator Research

    Energy Technology Data Exchange (ETDEWEB)

    Temkin, Richard [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Physics. Plasma Science and Fusion Center

    2016-07-12

    The goal of the MIT program of research on high gradient acceleration is the development of advanced acceleration concepts that lead to a practical and affordable next generation linear collider at the TeV energy level. Other applications, which are more near-term, include accelerators for materials processing; medicine; defense; mining; security; and inspection. The specific goals of the MIT program are: • Pioneering theoretical research on advanced structures for high gradient acceleration, including photonic structures and metamaterial structures; evaluation of the wakefields in these advanced structures • Experimental research to demonstrate the properties of advanced structures both in low-power microwave cold test and high-power, high-gradient test at megawatt power levels • Experimental research on microwave breakdown at high gradient including studies of breakdown phenomena induced by RF electric fields and RF magnetic fields; development of new diagnostics of the breakdown process • Theoretical research on the physics and engineering features of RF vacuum breakdown • Maintaining and improving the Haimson / MIT 17 GHz accelerator, the highest frequency operational accelerator in the world, a unique facility for accelerator research • Providing the Haimson / MIT 17 GHz accelerator facility as a facility for outside users • Active participation in the US DOE program of High Gradient Collaboration, including joint work with SLAC and with Los Alamos National Laboratory; participation of MIT students in research at the national laboratories • Training the next generation of Ph. D. students in the field of accelerator physics.

  5. Rapid Preparation of a Plasma Membrane Fraction: Western Blot Detection of Translocated Glucose Transporter 4 from Plasma Membrane of Muscle and Adipose Cells and Tissues.

    Science.gov (United States)

    Yamamoto, Norio; Yamashita, Yoko; Yoshioka, Yasukiyo; Nishiumi, Shin; Ashida, Hitoshi

    2016-08-01

    Membrane proteins account for 70% to 80% of all pharmaceutical targets, indicating their clinical relevance and underscoring the importance of identifying differentially expressed membrane proteins that reflect distinct disease properties. The translocation of proteins from the bulk of the cytosol to the plasma membrane is a critical step in the transfer of information from membrane-embedded receptors or transporters to the cell interior. To understand how membrane proteins work, it is important to separate the membrane fraction of cells. This unit provides a protocol for rapidly obtaining plasma membrane fractions for western blot analysis. © 2016 by John Wiley & Sons, Inc. Copyright © 2016 John Wiley & Sons, Inc.

  6. Ferromagnetic particles as a rapid and robust sample preparation for the absolute quantification of seven eicosanoids in human plasma by UHPLC-MS/MS.

    Science.gov (United States)

    Suhr, Anna Catharina; Bruegel, Mathias; Maier, Barbara; Holdt, Lesca Miriam; Kleinhempel, Alisa; Teupser, Daniel; Grimm, Stefanie H; Vogeser, Michael

    2016-06-01

    We used ferromagnetic particles as a novel technique to deproteinize plasma samples prior to quantitative UHPLC-MS/MS analysis of seven eicosanoids [thromboxane B2 (TXB2), prostaglandin E2 (PGE2), PGD2, 5-hydroxyeicosatetraenoic acid (5-HETE), 11-HETE, 12-HETE, arachidonic acid (AA)]. A combination of ferromagnetic particle enhanced deproteination and subsequent on-line solid phase extraction (on-line SPE) realized quick and convenient semi-automated sample preparation-in contrast to widely used manual SPE techniques which are rather laborious and therefore impede the investigation of AA metabolism in larger patient cohorts. Method evaluation was performed according to a protocol based on the EMA guideline for bioanalytical method validation, modified for endogenous compounds. Calibrators were prepared in ethanol. The calibration curves were found to be linear in a range of 0.1-80ngmL(-1) (TXB2, PGE2, PGD2), 0.05-40ngmL(-1) (5-HETE, 11-HETE), 0.5-400ngmL(-1) (12-HETE) and 25-9800ngmL(-1) (AA). Regarding all analytes and all quality controls, the resulting precision data (inter-assay 2.6 %-15.5 %; intra-assay 2.5 %-15.1 %, expressed as variation coefficient) as well as the accuracy results (inter-assay 93.3 %-125 %; intra-assay 91.7 %-114 %) were adequate. Further experiments addressing matrix effect, recovery and robustness, yielded also very satisfying results. As a proof of principle, the newly developed LC-MS/MS assay was employed to determine the capacity of AA metabolite release after whole blood stimulation in healthy blood donors. For this purpose, whole blood specimens of 5 healthy blood donors were analyzed at baseline and after a lipopolysaccharide (LPS) induced blood cell activation. In several baseline samples some eicosanoids levels were below the Lower Limit of Quantification. However, in the stimulated samples all chosen eicosanoids (except PGD2) could be quantified. These results, in context with those obtained in validation, demonstrate the

  7. Structural and mechanical characterization of rapidly solidified Al{sub 95}Ni{sub 5} and Al{sub 93}Ni{sub 5}Mm{sub 2} alloys prepared by centrifugal atomization

    Energy Technology Data Exchange (ETDEWEB)

    Vojtech, D., E-mail: Dalibor.Vojtech@vscht.c [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technicka 5, 166 28 Prague 6 (Czech Republic); Prusa, F.; Michalcova, A. [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technicka 5, 166 28 Prague 6 (Czech Republic)

    2010-09-17

    Research highlights: {yields} Structure and properties of a rapidly solidified Al-Ni-Mm alloy with a relatively low Mm content. {yields} Comparison of slowly and rapidly solidified state. {yields} High hardness of the RS Al-Ni-Mm alloy, but low thermal stability. {yields} Chemical compositions of metastable primary phases in the RS Al-Ni-Mm alloy. - Abstract: Al{sub 95}Ni{sub 5} and Al{sub 93}Ni{sub 5}Mm{sub 2} (at.%) alloys were prepared by induction melting and centrifugal atomization. Both as-cast and rapidly solidified (RS) alloys were studied by various techniques, including light, scanning and transmission electron microscopy, energy dispersion spectrometry, differential scanning calorimetry and X-ray diffraction analysis. Room temperature hardness was measured for the rapidly solidified alloys, as well as after their long-term annealing at 400 {sup o}C. It is observed that the RS alloys are crystalline. The binary Al-Ni alloy consists of Al and Al{sub 3}Ni phases, while in the ternary Al-Ni-Mm alloy, there are Al dendrites supersaturated with Ni, Al{sub 3}Ni and non-equilibrium {alpha}Al{sub 11}(Mm,Ni){sub 3} phases. Average Al dendrite arm thickness is about 100 nm. Both supersaturated Al and {alpha}Al{sub 11}(Mm,Ni){sub 3} decompose upon heating at 300-450 {sup o}C. Room temperature hardness of the RS Al{sub 95}Ni{sub 5} and Al{sub 93}Ni{sub 5}Mm{sub 2} alloys are 150 and 300 HV, respectively. These values are discussed in relation to various hardening mechanisms. Thermal stability of both alloys is low, due a rapid structural coarsening and hardness reduction during annealing at 400 {sup o}C.

  8. Uniform gradient expansions

    Directory of Open Access Journals (Sweden)

    Massimo Giovannini

    2015-06-01

    Full Text Available Cosmological singularities are often discussed by means of a gradient expansion that can also describe, during a quasi-de Sitter phase, the progressive suppression of curvature inhomogeneities. While the inflationary event horizon is being formed the two mentioned regimes coexist and a uniform expansion can be conceived and applied to the evolution of spatial gradients across the protoinflationary boundary. It is argued that conventional arguments addressing the preinflationary initial conditions are necessary but generally not sufficient to guarantee a homogeneous onset of the conventional inflationary stage.

  9. Uniform gradient expansions

    Energy Technology Data Exchange (ETDEWEB)

    Giovannini, Massimo, E-mail: massimo.giovannini@cern.ch [Department of Physics, Theory Division, CERN, 1211 Geneva 23 (Switzerland); INFN, Section of Milan-Bicocca, 20126 Milan (Italy)

    2015-06-30

    Cosmological singularities are often discussed by means of a gradient expansion that can also describe, during a quasi-de Sitter phase, the progressive suppression of curvature inhomogeneities. While the inflationary event horizon is being formed the two mentioned regimes coexist and a uniform expansion can be conceived and applied to the evolution of spatial gradients across the protoinflationary boundary. It is argued that conventional arguments addressing the preinflationary initial conditions are necessary but generally not sufficient to guarantee a homogeneous onset of the conventional inflationary stage.

  10. Gradient systems and mechanical systems

    Institute of Scientific and Technical Information of China (English)

    Fengxiang Mei; Huibin Wu

    2016-01-01

    All types of gradient systems and their properties are discussed. Two problems connected with gradient sys-tems and mechanical systems are studied. One is the direct problem of transforming a mechanical system into a gradi-ent system, and the other is the inverse problem, which is transforming a gradient system into a mechanical system.

  11. Interfacial reaction and electrical properties of HfO2 film gate dielectric prepared by pulsed laser deposition in nitrogen: role of rapid thermal annealing and gate electrode.

    Science.gov (United States)

    Wang, Yi; Wang, Hao; Ye, Cong; Zhang, Jun; Wang, Hanbin; Jiang, Yong

    2011-10-01

    The high-k dielectric HfO(2) thin films were deposited by pulsed laser deposition in nitrogen atmosphere. Rapid thermal annealing effect on film surface roughness, structure and electrical properties of HfO(2) film was investigated. The mechanism of interfacial reaction and the annealing atmosphere effect on the interfacial layer thickness were discussed. The sample annealed in nitrogen shows an amorphous dominated structure and the lowest leakage current density. Capacitors with high-k HfO(2) film as gate dielectric were fabricated, using Pt, Au, and Ti as the top gate electrode whereas Pt constitutes the bottom side electrode. At the gate injection case, the Pt- and Au-gated metal oxide semiconductor devices present a lower leakage current than that of the Ti-gated device, as well as similar leakage current conduction mechanism and interfacial properties at the metal/HfO(2) interface, because of their close work function and chemical properties.

  12. Preparation of novel curcumin-imprinted polymers based on magnetic multi-walled carbon nanotubes for the rapid extraction of curcumin from ginger powder and kiwi fruit root.

    Science.gov (United States)

    Zhang, Zhaohui; Chen, Xing; Rao, Wei; Long, Fang; Yan, Liang; Yin, Yuli

    2015-01-01

    A novel molecularly imprinted polymer based on magnetic phenyl-modified multi-walled carbon nanotubes was synthesized using curcumin as the template molecule, methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross-linker. The phenyl groups contained in the magnetic imprinted polymers acted as the assisting functional monomer. The magnetic imprinted polymers were characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy and vibrating sample magnetometry. Adsorption studies demonstrated that the magnetic imprinted polymers possessed excellent selectivity toward curcumin with a maximum capacity of 16.80 mg/g. Combining magnetic extraction and high-performance liquid chromatography technology, the magnetic imprinted polymer based on magnetic phenyl-modified multi-walled carbon nanotubes was applied for the rapid separation and enrichment of curcumin from ginger powder and kiwi fruit root successfully.

  13. Rapid determination of {sup 90}Sr impurities in freshly 'generator eluted'{sup 90}Y for radiopharmaceutical preparation

    Energy Technology Data Exchange (ETDEWEB)

    Bonardi, Mauro L. [LASA, Universita degli Studi di Milano and INFN-Milano, via F.lli Cervi 201, I-20090 Segrate, Milano (Italy); Martano, Luigi [Division of Nuclear Medicine, European Institute of Oncology, via G. Ripamonti 435, I-20141 Milano (Italy); Groppi, Flavia [LASA, Universita degli Studi di Milano and INFN-Milano, via F.lli Cervi 201, I-20090 Segrate, Milano (Italy); Chinol, Marco [Division of Nuclear Medicine, European Institute of Oncology, via G. Ripamonti 435, I-20141 Milano (Italy)], E-mail: marco.chinol@ieo.it

    2009-10-15

    {sup 90}Y is one of the most useful radionuclides for radioimmunotherapeutic applications and has a half-life (t{sub 1/2}=64.14 h) suitable for most therapeutic applications, beta particles of high energy and decays to a stable daughter. It is significant that {sup 90}Y is available conveniently and inexpensively from a radionuclide 'generator' by decay of its parent, {sup 90}Sr. Nevertheless, current and planned clinical applications with [{sup 90}Y] labelled compounds employ activity levels that cannot be readily obtained from an in-house generator, but from commercial sources. We have evaluated Eichrom's Sr-resin, either as an 'in-house' generator or as a fast QC method for analysis of {sup 90}Y solutions. In particular, for the development as a generator, we investigated the percentage of the radio-Sr in the first 8 M HNO{sub 3} eluate: in this fraction the concentration of {sup 90}Sr must be smaller than 10{sup -5}% (recommendations of the International Commission on Radiological Protection). For evaluation as a rapid QC method, we analyzed the concentration of {sup 90}Y in all the fractions containing 'only' radio-Sr: {sup 90}Y should not be present in these eluates. After the collection of {beta}{sup -} and {gamma} spectra and analysis of them, we concluded that commercial Sr-resin minicolumn cannot give us the results expected; we developed an in-house system loaded with 4 mL of Sr-resin which gave better results as a generator and a rapid QC method.

  14. Improved sample preparation and rapid UHPLC analysis of SO2 binding carbonyls in wine by derivatisation to 2,4-dinitrophenylhydrazine.

    Science.gov (United States)

    Jackowetz, J N; Mira de Orduña, R

    2013-08-15

    Sulphur dioxide (SO2) is essential for the preservation of wines. The presence of SO2 binding compounds in musts and wines may limit sulphite efficacy leading to higher total SO2 additions, which may exceed SO2 limits permitted by law and pose health risks for sensitive individuals. An improved method for the quantification of significant wine SO2 binding compounds is presented that applies a novel sample treatment approach and rapid UHPLC separation. Glucose, galacturonic acid, alpha-ketoglutarate, pyruvate, acetoin and acetaldehyde were derivatised with 2,4-dinitrophenylhydrazine and separated using a solid core C18 phase by ultra high performance liquid chromatography. Addition of EDTA to samples prevented de novo acetaldehyde formation from ethanol oxidation. Optimised derivatisation duration enhanced reproducibility and allowed for glucose and galacturonic acid quantification. High glucose residues were found to interfere with the recovery of other SO2 binders, but practical SO2 concentrations and red wine pigments did not affect derivatisation efficiency. The calibration range, method accuracy, precision and limits of detection were found to be satisfactory for routine analysis of SO2 binders in wines. The current method represents a significant improvement in the comprehensive analysis of SO2 binding wine carbonyls. It allows for the quantification of major SO2 binders at practical analyte concentrations, and uses a simple sample treatment method that prevents treatment artifacts. Equipment utilisation could be reduced by rapid LC separation while maintaining analytical performance parameters. The improved method will be a valuable addition for the analysis of total SO2 binder pools in oenological samples. Published by Elsevier Ltd.

  15. Preparation of immunomagnetic iron-dextran nanoparticles and application in rapid isolation of E.coli O157:H7 from foods

    Institute of Scientific and Technical Information of China (English)

    Hui-Li Duan; Zhi-Qiang Shen; Xin-Wei Wang; Fu-Huan Chao; Jun-Wen Li

    2005-01-01

    AIM: To prepare a kind of magnetic iron-dextran nanopartidesthat was coated with anti-E.coli O157:H7 IgG, analyze its application conditions, and try to use it to isolate E.coli O157:H7 from foods.METHODS: Magnetic iron-dextran nanoparticles were prepared by the reaction of a mixture of ferric and ferrous ions with dextran polymers under alkaline conditions. The particles were coated with antiserum against E. coli O157:H7 by the periodate oxidation-borohydride reduction procedure. The oxidation time, amount of antibody coating the particles, amount of nanoparticles, incubation time and isolation time were varied to determine their effects on recovery of the organisms. Finally, the optimumconditions for isolating E. coli O157:H7 from food samples were established.RESULTS: E.coli O157:H7 can be isolated from samples within 15 min with the sensitivity of 101 CFU/mL or even less. In the presence of 108 CFU/mL of other organisms,the sensitivity is 101-102 CFU/mL. Nonspecific binding of other bacteria to the particles was not observed. Two and a half hours of enrichment is enough for the particles to detect the target from the food samples inoculated with 1 CFU/g.CONCLUSION: Isolation of target bacteria by immunomagnetic nanoparticles is an efficient method with high sensitivity and specificity. The technique is so simple that it can be operated in lab and field even by untrained personnel.

  16. Gravity gradient-terrain aided navigation based on particle filter

    Science.gov (United States)

    Xiong, Ling; Ma, Jie; Tian, Jin-Wen

    2009-10-01

    Based on Particle Filter, Gravity Gradient-Terrain aided position technology is proposed in this paper. With the sensitivity of gravity gradient to terrain, the gravity gradient reference map can be computed from the local terrain elevation data. The position can be actualized through matching the real-time measured gravity gradient data to the prepared gravity gradient reference map. The most widely used approximate filtering method is the extended Kaman filter (EKF). EKF is computationally simple but, the convergence of the state estimation for the position is not guaranteed. Particle filter (PF) makes use of the non-linear state and measurement functions, no linearization technology is needed. PF can assure the convergence of the state estimation which follows from the classical results on convergence of Bayesian estimators. Simulations have been done and Particle filter has been shown to be a superior alternative to the EKF in the gravity gradient-terrain matching navigation systems.

  17. Rapid and facile preparation of zinc ferrite (ZnFe{sub 2}O{sub 4}) oxide by microwave-solvothermal technique and its catalytic activity in heterogeneous photo-Fenton reaction

    Energy Technology Data Exchange (ETDEWEB)

    Anchieta, Chayene G.; Severo, Eric C.; Rigo, Caroline; Mazutti, Marcio A. [Department of Chemical Engineering, Federal University of Santa Maria, 97105-900, Santa Maria (Brazil); Kuhn, Raquel C., E-mail: raquelckuhn@yahoo.com.br [Department of Chemical Engineering, Federal University of Santa Maria, 97105-900, Santa Maria (Brazil); Muller, Edson I.; Flores, Erico M.M. [Department of Chemistry, Federal University of Santa Maria, 97105-900, Santa Maria (Brazil); Moreira, Regina F.P.M. [Department of Chemical Engineering and Food Engineering, Federal University of Santa Catarina, 88040-970, Florianópolis (Brazil); Foletto, Edson L. [Department of Chemical Engineering, Federal University of Santa Maria, 97105-900, Santa Maria (Brazil)

    2015-06-15

    In this work zinc ferrite (ZnFe{sub 2}O{sub 4}) oxide was rapidly and easily prepared by microwave-solvothermal route and its catalytic property in photo-Fenton reaction was evaluated. The effects of microwave heating time and power on the properties of produced particles were investigated. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and nitrogen adsorption–desorption isotherms were the techniques used for characterizing the solid products. The synthesized material was tested as a catalyst in the degradation of the textile dye molecule by the heterogeneous photo-Fenton process. Characterization results showed that the microwave heating time and power have significant influences on the formation of the phase spinel as well as on its physical properties. The reaction results showed that the ZnFe{sub 2}O{sub 4} oxide has good photocatalytic activity, which can be attributed to high surface area and pore volume, and large pore size. The ZnFe{sub 2}O{sub 4} oxide produced by the microwave irradiation exhibited promising photocatalytic activity for the removal of textile dye, reaching nearly 100% of decolorization at 40 min and 60% of mineralization at 240 min. Therefore, ZnFe{sub 2}O{sub 4} particles rapidly prepared by the microwave route have the potential for use in treatment of textile wastewater by the heterogeneous photo-Fenton process. - Highlights: • ZnFe{sub 2}O{sub 4} was synthesized by microwave-solvothermal method. • ZnFe{sub 2}O{sub 4} was prepared by different microwave heating times and powers. • ZnFe{sub 2}O{sub 4} was used as heterogeneous photo-Fenton catalyst. • Degradation of Procion red dye using heterogeneous photo-Fenton process. • ZnFe{sub 2}O{sub 4} was highly efficient to degrade textile dye under visible light.

  18. Optimization of Sample Preparation and Instrumental Parameters for the Rapid Analysis of Drugs of Abuse in Hair samples by MALDI-MS/MS Imaging

    Science.gov (United States)

    Flinders, Bryn; Beasley, Emma; Verlaan, Ricky M.; Cuypers, Eva; Francese, Simona; Bassindale, Tom; Clench, Malcolm R.; Heeren, Ron M. A.

    2017-08-01

    Matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) has been employed to rapidly screen longitudinally sectioned drug user hair samples for cocaine and its metabolites using continuous raster imaging. Optimization of the spatial resolution and raster speed were performed on intact cocaine contaminated hair samples. The optimized settings (100 × 150 μm at 0.24 mm/s) were subsequently used to examine longitudinally sectioned drug user hair samples. The MALDI-MS/MS images showed the distribution of the most abundant cocaine product ion at m/z 182. Using the optimized settings, multiple hair samples obtained from two users were analyzed in approximately 3 h: six times faster than the standard spot-to-spot acquisition method. Quantitation was achieved using longitudinally sectioned control hair samples sprayed with a cocaine dilution series. A multiple reaction monitoring (MRM) experiment was also performed using the `dynamic pixel' imaging method to screen for cocaine and a range of its metabolites, in order to differentiate between contaminated hairs and drug users. Cocaine, benzoylecgonine, and cocaethylene were detectable, in agreement with analyses carried out using the standard LC-MS/MS method. [Figure not available: see fulltext.

  19. Preparation of hybrid molecularly imprinted polymer with double-templates for rapid simultaneous purification of theophylline and chlorogenic acid in green tea.

    Science.gov (United States)

    Tang, Weiyang; Li, Guizhen; Row, Kyung Ho; Zhu, Tao

    2016-05-15

    A novel double-templates technique was adopted for solid-phase extraction packing agent, and the obtained hybrid molecularly imprinted polymers with double-templates (theophylline and chlorogenic acid) were characterized by fourier transform infrared and field emission scanning electron microscope. The molecular recognition ability and binding capability for theophylline and chlorogenic acid of polymers was evaluated by static absorption and dynamic adsorption curves. A rapid and accurate approach was established for simultaneous purification of theophylline and chlorogenic acid in green tea by coupling hybrid molecularly imprinted solid-phase extraction with high performance liquid chromatography. With optimization of SPE procedure, a reliable analytical method was developed for highly recognition towards theophylline and chlorogenic acid in green tea with satisfactory extraction recoveries (theophylline: 96.7% and chlorogenic acid: 95.8%). The limit of detection and limit of quantity of the method were 0.01 μg/mL and 0.03 μg/mL for theophylline, 0.05 μg/mL and 0.17 μg/mL for chlorogenic acid, respectively. The recoveries of proposed method at three spiked levels analysis were 98.7-100.8% and 98.3-100.2%, respectively, with the relative standard deviation less than 1.9%. Hybrid molecularly imprinted polymers with double-templates showed good performance for two kinds of targets, and the proposed approach with high affinity of hybrid molecularly imprinted polymers might offer a novel method for the purification of complex samples.

  20. Bigravity from gradient expansion

    Energy Technology Data Exchange (ETDEWEB)

    Yamashita, Yasuho [Yukawa Institute for Theoretical Physics, Kyoto University,606-8502, Kyoto (Japan); Tanaka, Takahiro [Yukawa Institute for Theoretical Physics, Kyoto University,606-8502, Kyoto (Japan); Department of Physics, Kyoto University,606-8502, Kyoto (Japan)

    2016-05-04

    We discuss how the ghost-free bigravity coupled with a single scalar field can be derived from a braneworld setup. We consider DGP two-brane model without radion stabilization. The bulk configuration is solved for given boundary metrics, and it is substituted back into the action to obtain the effective four-dimensional action. In order to obtain the ghost-free bigravity, we consider the gradient expansion in which the brane separation is supposed to be sufficiently small so that two boundary metrics are almost identical. The obtained effective theory is shown to be ghost free as expected, however, the interaction between two gravitons takes the Fierz-Pauli form at the leading order of the gradient expansion, even though we do not use the approximation of linear perturbation. We also find that the radion remains as a scalar field in the four-dimensional effective theory, but its coupling to the metrics is non-trivial.

  1. Rapid preparative isolation of erythrocentaurin from Enicostemma littorale by medium-pressure liquid chromatography, its estimation by high-pressure thin-layer chromatography, and its α-amylase inhibitory activity.

    Science.gov (United States)

    Hassan, Naila; Ahamad, Javed; Amin, Saima; Mujeeb, Mohd; Mir, Showkat R

    2015-02-01

    Erythrocentaurin is a relatively simple natural product present among the members of Gentianaceae. A preparative method for the isolation of erythrocentaurin from the ethyl acetate fraction of Enicostemma littorale using medium-pressure liquid chromatography has been reported. The method consisted of a simple step gradient from 10 to 20% ethyl acetate in n-hexane. Using a 70 × 460 mm Si60 column, this method is capable of processing 20 g of material in thin-layer chromatography was carried out on silica gel 60 F(254) plates with toluene/ethyl acetate/formic acid (80:18:2 v/v/v) as the mobile phase. The densitometric analysis was performed at 230 nm. A well-separated compact band of erythrocentaurin appeared at R(f )0.54 ± 0.04. The analytical method showed good linearity in the concentration range of 200-1500 ng/band with a correlation coefficient of 0.99417. The limits of detection and quantification were found to be ≈60 and ≈180 ng/band, respectively. Erythrocentaurin exhibited a concentration-dependent α-amylase inhibition (IC(50) 1.67 ± 0.28 mg/mL). The outcome of the study should be considered for pharmacokinetic and biotransformation studies involving E. littorale. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Intrinsic advantages of packed capillaries over narrow-bore columns in very high-pressure gradient liquid chromatography.

    Science.gov (United States)

    Gritti, Fabrice; McDonald, Thomas; Gilar, Martin

    2016-06-17

    250μm×100mm fused silica glass capillaries were packed with 1.8μm high-strength silica (HSS) fully porous particles. They were prepared without bulky stainless steel endfittings and metal frits, which both generate significant sample dispersion. The isocratic efficiencies and gradient peak capacities of these prototype capillary columns were measured for small molecules (n-alkanophenones) using a home-made ultra-low dispersive micro-HPLC instrument. Their resolution power was compared to that of standard 2.1mm×100mm very high-pressure liquid chromatography (vHPLC) narrow-bore columns packed with the same particles. The results show that, for the same column efficiency (25000 plates) and gradient steepness (0.04min(-1)), the peak capacity of the 250μm i.d. capillary columns is systematically 15-20% higher than that of the 2.1mm i.d. narrow-bore columns. A validated model of gradient chromatography enabled one to predict accurately the observed peak capacities of the capillary columns for non-linear solvation strength retention behavior and under isothermal conditions. Thermodynamics applied to the eluent quantified the temperature difference for the thermal gradients in both capillary and narrow-bore columns. Experimental data revealed that the gradient peak capacity is more affected by viscous heating than the column efficiency. Unlike across 2.1mm i.d. columns, the changes in eluent composition across the 250μm i.d. columns during the gradient is rapidly relaxed by transverse dispersion. The combination of (1) the absence of viscous heating and (2) the high uniformity of the eluent composition across the diameter of capillary columns explains the intrinsic advantage of capillary over narrow-bore columns in gradient vHPLC.

  3. Increasing SLEDed Linac Gradient

    Energy Technology Data Exchange (ETDEWEB)

    Farkas, Zoltan D

    2001-11-08

    This note will show how to increase the SLED [1] gradient by varying Q{sub e}, the external Q of the SLED cavity, by increasing its Q{sub 0} and by increasing the compression ratio. If varying the external Q is to be effective, then the copper losses should be small so that Q{sub 0} >> Q{sub e}. Methods of varying Q{sub e} will be indicated but no experimental data will be presented. If we increase the klystron pulse width from 3.5 to 5 {micro}S and increase Q{sub 0} from the present 100000 to 300000, then the gradient increases by 19% and the beam energy increases from 50 to 60 GeV. This note will also discuss SLED operation at 11424 MHz, the NLC frequency. Without Q{sub e} switching, using SLED at 11424 MHz increases the SLAC gradient from 21 MV/m to 34 MV/m, and at the same repetition rate, uses about 1/5 of rf average power. If we also double the compression ratio, we reach 47 MV/m and over 100 GeV beam energy.

  4. Evaluation in an emergency department of rapid separator tubes containing thrombin for serum preparation prior to hs-cTnT and CK-MB analyses.

    Science.gov (United States)

    Budak, Yasemin U; Huysal, Kagan; Bulut, Mehtap; Polat, Murat

    2013-01-01

    In our emergency department, we collect blood in Rapid Serum Tubes (RSTs; Becton Dickinson, Franklin Lakes, NJ), in which clotting times are reduced. We investigated the influence of RST use on cardiac troponin T (hs-cTnT) and creatine kinase-MB (CK-MB) test results, in comparison with the use of tubes featuring a separator gel containing a clotting activator (SSTs; Green-vac, Yongin, Korea). Samples from 60 patients were divided into equal aliquots and placed into RSTs and SSTs; hs-cTnT and CK-MB concentrations were determined using an autoanalyzer (Elecsys 2010) running commercial assays (Roche Diagnostics, Penzberg, Germany). Between-tube differences in CK-MB and hs-cTnT values were compared using the paired t-test, and correlations among variables were evaluated by calculation of Spearman correlation coefficients (r values). Deming regression analysis was performed and Bland-Altman plots were constructed. The hs-cTnT and CK-MB test results obtained from samples placed into RSTs and SSTs did not differ (p > 0.1). The correlations between the concentrations of hs-cTnT and CK-MB in samples placed into RSTs and SSTs were good; both r values were unity (p MB] = 0.95 SST [CK-MB]-0.09 ng/ml. The biases of 1.4 pg/ml (95% CI: minus 8.1-10.7 pg/ml) for hs-cTnT levels and 0.249 ng/ml (95% CI: minus 0.682-1.681 ng/ml) for CK-MB levels assayed using either tube was acceptable. The hs-cTnT and CK-MB test results did not significantly differ when either tube was used. RST tube use was associated with a short clotting time; this was an advantage in an emergency laboratory setting.

  5. Preparation of a test kit for rapid and on site determination of fluoride in water%水中氟化物现场快速测试盒的研制

    Institute of Scientific and Technical Information of China (English)

    秦惠; 邓金花; 傅妍芳; 陈维

    2011-01-01

    基于氟试剂分光光度法的显色原理,采用目视比色法和试剂定量包装技术构建氟化物现场快速测试盒.该测试盒具有便于携带、操作简便、快速、测试结果准确等特点,测试范围为0.05 ~1.20 mg,/L.%Based on the principle of the color reaction of fluoride-reagent spectrophotometric method,the visual colorimetric method and reagent quantitative packing technique are used to prepare an on-site flouride test kit. This test kit is easy to carry and use with rapid and accurate determination. The determination range of the kit is 0.05 -1. 2 mg/L.

  6. Preparation of tissue engineering scaffolds using rapid prototyping%快速成型方法制备组织工程支架的研究与应用**

    Institute of Scientific and Technical Information of China (English)

    张建明; 刘璐; 张西正; 李瑞欣; 任婷婷; 李昊; 王贺燕; 郝庆新; 万宗明; 李建宇

    2013-01-01

    BACKGROUND: Rapid Prototyping is a high-tech manufacturing technique based on material accumulation to be combined with computer, numerical control, laser and material technologies. OBJECTIVE: To review the application of rapid prototyping in the preparation of tissue engineering scaffolds. METHODS: The first author retrieved Wanfang, CNKI, and Elsevier Science Direct Online for articles about biomechanical ability and developmental prospect of scaffold materials, as wel as the application of rapid prototyping in the preparation of scaffold materials.RESULTS AND CONCLUSION: Rapid prototyping has become mature gradual y in the preparation of tissue engineering scaffolds. This technology can not only overcome the difficulty in shaping and internal microstructural control, but also optimize the scaffold structure via the finite element analysis, achieving some special requirements such as the improvement of mechanical strength. However, due to the particularity of tissue organ, and xenophobic sex and cel adhesion conditions, it is pre-requisite to combine rapid prototyping technology with biodegradable materials with histocompatibility in order to make the cells proliferation and differentiation better, promote tissue regeneration, and repair tissue defects.%  背景:快速成型是基于材料堆积法,结合计算机、数控、激光和材料技术于一体的高新制造技术。目的:综述快速成型技术在组织工程支架制备中的应用。方法:由第一作者检索万方数据库、中国知网数据库和 Elsevier Science Direct Online 有关支架材料的生物力学性能、支架材料发展前景及快速成型技术在支架材料制备领域中应用研究等方面的文献。结果与结论:快速成型技术应用于组织工程支架的制备已经越来越成熟,快速成型技术不但克服了传统制造方法中存在的支架复杂外形制造困难和内部微结构无法控制的缺陷,而且还可以通过有限

  7. Reinforcement Learning by Value Gradients

    CERN Document Server

    Fairbank, Michael

    2008-01-01

    The concept of the value-gradient is introduced and developed in the context of reinforcement learning. It is shown that by learning the value-gradients exploration or stochastic behaviour is no longer needed to find locally optimal trajectories. This is the main motivation for using value-gradients, and it is argued that learning value-gradients is the actual objective of any value-function learning algorithm for control problems. It is also argued that learning value-gradients is significantly more efficient than learning just the values, and this argument is supported in experiments by efficiency gains of several orders of magnitude, in several problem domains. Once value-gradients are introduced into learning, several analyses become possible. For example, a surprising equivalence between a value-gradient learning algorithm and a policy-gradient learning algorithm is proven, and this provides a robust convergence proof for control problems using a value function with a general function approximator.

  8. FFAGS for rapid acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Carol J. Johnstone and Shane Koscielniak

    2002-09-30

    When large transverse and longitudinal emittances are to be transported through a circular machine, extremely rapid acceleration holds the advantage that the beam becomes immune to nonlinear resonances because there is insufficient time for amplitudes to build up. Uncooled muon beams exhibit large emittances and require fast acceleration to avoid decay losses and would benefit from this style of acceleration. The approach here employs a fixed-field alternating gradient or FFAG magnet structure and a fixed frequency acceleration system. Acceptance is enhanced by the use only of linear lattice elements, and fixed-frequency rf enables the use of cavities with large shunt resistance and quality factor.

  9. Variable-Temperature-Gradient Device for Solidification Research

    Science.gov (United States)

    Kaukler, W. F.

    1985-01-01

    Device for research in solidification and crystal growth allows crystallization of melt observed as occurs. Temperature gradient across melt specimen increased or decreased rapidly while solidification front proceeds at constant speed across sample. Device moves sample at same speed, thereby holding position of liquid/solid interface stationary within field of optical microscope. Device, variabletemperature-gradient microscope stage, used to study crystal growth at constant rate while thermal driving force is varied.

  10. Composition Gradient Hard Coatings by Arc Ion Plating

    Institute of Scientific and Technical Information of China (English)

    CHEN Jun; LIN Guo-qiang; WANG Fu-gang

    2004-01-01

    Arc Ion Plating can be used to synthesize multi-component composition gradient hard coatings by adjusting arc currents of metal targets. The present work aims at a comprehensive description of such a technique. The examples of TiAl multi-layer alloy coatings and (Ti, M) N composition-gradient films were taken (M representing Zr, Nb etc.) for the purpose of explaining the working process and evaluating practical effects. The results show that this technique has the advantages of easy manipulation, rapid deposition, and wide composition range.Key Words: Arc Ion plating, hard coating, composition gradient coatings

  11. Energy in density gradient

    CERN Document Server

    Vranjes, J

    2015-01-01

    Inhomogeneous plasmas and fluids contain energy stored in inhomogeneity and they naturally tend to relax into lower energy states by developing instabilities or by diffusion. But the actual amount of energy in such inhomogeneities has remained unknown. In the present work the amount of energy stored in a density gradient is calculated for several specific density profiles in a cylindric configuration. This is of practical importance for drift wave instability in various plasmas, and in particular in its application in models dealing with the heating of solar corona because the instability is accompanied with stochastic heating, so the energy contained in inhomogeneity is effectively transformed into heat. It is shown that even for a rather moderate increase of the density at the axis in magnetic structures in the corona by a factor 1.5 or 3, the amount of excess energy per unit volume stored in such a density gradient becomes several orders of magnitude greater than the amount of total energy losses per unit ...

  12. Energy in density gradient

    Energy Technology Data Exchange (ETDEWEB)

    Vranjes, J., E-mail: jvranjes@yahoo.com [Instituto de Astrofísica de Canarias, 38205 La Laguna, Tenerife (Spain); Departamento de Astrofísica, Universidad de La Laguna, 38205 La Laguna, Tenerife (Spain); Kono, M., E-mail: kono@fps.chuo-u.ac.jp [Faculty of Policy Studies, Chuo University, Tokyo (Japan)

    2015-01-15

    Inhomogeneous plasmas and fluids contain energy stored in inhomogeneity and they naturally tend to relax into lower energy states by developing instabilities or by diffusion. But the actual amount of energy in such inhomogeneities has remained unknown. In the present work, the amount of energy stored in a density gradient is calculated for several specific density profiles in a cylindrical configuration. This is of practical importance for drift wave instability in various plasmas, and, in particular, in its application in models dealing with the heating of solar corona because the instability is accompanied with stochastic heating, so the energy contained in inhomogeneity is effectively transformed into heat. It is shown that even for a rather moderate increase of the density at the axis in magnetic structures in the corona by a factor 1.5 or 3, the amount of excess energy per unit volume stored in such a density gradient becomes several orders of magnitude greater than the amount of total energy losses per unit volume (per second) in quiet regions in the corona. Consequently, within the life-time of a magnetic structure such energy losses can easily be compensated by the stochastic drift wave heating.

  13. 孔梯度陶瓷纤维复合膜管的制备及特性%Preparation and Characterization of Filtering Tube of Ceramic Composite with Pore-gradient Structure

    Institute of Scientific and Technical Information of China (English)

    王耀明; 薛友祥; 孟宪谦; 张联盟

    2007-01-01

    Ceramic filters have a great potential for applications in high temperature dust collection due to their high erosion resistance and mechanical strength at elevated temperatures. In this work, a filtering tube of cordierite ceramic composite with pore-gradient structure was fabricated and studied, which is made up of a porous cordierite ceramic support, a transition layer and a separation layer of fiber-reinforced composite, having a porosity of 35%-40%, 50%-60% and 60%-70%, respectively. The thermal shock resistance test against the temperature difference of ca. 1000℃ and room temperature simulation on dust gas filtration were mainly carried out. The results show that the total filtration efficiency of the dust particulates larger than 0. 1μm is 98.5% and maximum value reaches to 99.9%.%陶瓷过滤管具有孔隙率高、耐腐蚀、耐高温、机械强度高、便于清洗、使用寿命长等优点,是高温烟尘处理用的高效过滤元件.本文研制了一种具有梯度孔结构堇青石陶瓷纤维复合膜过滤元件,该过滤元件是由多孔支撑体、过渡层和分离膜层组成.其中支撑体、过渡层和分离层的气孔率分别为35~40%、50~60%和60~70%.文中主要分析了孔梯度陶瓷纤维复合膜管的材料结构和抗热震性能,同时对复合膜管进行含尘气体过滤的冷态模拟试验.对于烟气中粒径大于或等于0.1μm的颗粒,复合膜管的截留率达到99.8%以上.

  14. Colloidal attraction induced by a temperature gradient.

    Science.gov (United States)

    Di Leonardo, R; Ianni, F; Ruocco, G

    2009-04-21

    Colloidal crystals are of extreme importance for applied research and for fundamental studies in statistical mechanics. Long-range attractive interactions, such as capillary forces, can drive the spontaneous assembly of such mesoscopic ordered structures. However, long-range attractive forces are very rare in the colloidal realm. Here we report a novel strong, long-ranged attraction induced by a thermal gradient in the presence of a wall. By switching the thermal gradient on and off, we can rapidly and reversibly form stable hexagonal 2D crystals. We show that the observed attraction is hydrodynamic in nature and arises from thermally induced slip flow on particle surfaces. We used optical tweezers to measure the force law directly and compare it to an analytical prediction based on Stokes flow driven by Marangoni-like forces.

  15. Preparation and Photoinduced Hydrophilic Properties of (TiO2-ZnO)/TiO2 Gradient Thin Films by Magnetron Sputtering%磁控溅射(TiO2-ZnO)/TiO2梯度复合薄膜的制备及光致亲水性研究

    Institute of Scientific and Technical Information of China (English)

    寇钢; 白力静; 龚振瑶; 赵志明

    2012-01-01

    (TiO2-ZnO)/TiO2 gradient composite thin films were prepared by ion plating magnetron sputtering technique. The structure, morphology and surface hydroxy group of composite thin films were investigated by TEM, AFM, Raman and XPS. The differences of photocatalytic activity and hydrophilic property were analyzed between (TiO2-ZnO)/TiO2 gradient composite thin films and ordinary TiO2-ZnO, TiO2 thin films. The results show that the (TiO2-ZnO)/TiO2 composite gradient films were constituent of TiO2-ZnO composite key body and TiO2 top layer, the surface morphology of (TiO2-ZnO)/TiO2 film was compact and uniform, and the grain size was about 10-14 run. The photocatalysis and hydrophilic properties of (TiO2-ZnO)/TiO2 gradient composite films were better than ordinary TiO2-ZnO composite thin films and TiO2 thin films, and its light response region was extended to the visible region(450 nm). The XPS indicates that the surface hydroxy group of (TiO2-ZnO)/TiO2 gradient composite thin films were 12.53%. At the same time,The gradient composite thin films show excellent resistance to anti-photo corrosion and well stability of contact angle.%采用磁控溅射离子镀设备制备了(TiO2-ZnO)/TiO2梯度复合薄膜,通过TEM、AFM、Raman、XPS分析了复合薄膜的结构、形貌和表面羟基含量,以甲基橙作为有机降解物,研究了( TiO2 -ZnO )/TiO2梯度复合薄膜与普通TiO2-ZnO复合薄膜和TiO2薄膜在光催化性能和光致亲水性能上的差异.结果表明:(TiO2 -ZnO )/TiO2梯度复合薄膜具有以主体为TiO2 -ZnO层、顶层为TiO2的梯度结构,且薄膜表面致密、粒径均匀(10~14nm),光催化性和亲水性均优于普通TiO2 -ZnO复合薄膜和TiO2薄膜,且其光波响应范围红移至450nm、表面羟基含量高达12.53%,同时梯度复合薄膜的抗光腐蚀性能良好,4h以后其润湿角仍保持不变.

  16. Generalized conjugate gradient squared

    Energy Technology Data Exchange (ETDEWEB)

    Fokkema, D.R.; Sleijpen, G.L.G. [Utrecht Univ. (Netherlands)

    1994-12-31

    In order to solve non-symmetric linear systems of equations, the Conjugate Gradient Squared (CGS) is a well-known and widely used iterative method. In practice the method converges fast, often twice as fast as the Bi-Conjugate Gradient method. This is what you may expect, since CGS uses the square of the BiCG polynomial. However, CGS may suffer from its erratic convergence behavior. The method may diverge or the approximate solution may be inaccurate. BiCGSTAB uses the BiCG polynomial and a product of linear factors in an attempt to smoothen the convergence. In many cases, this has proven to be very effective. Unfortunately, the convergence of BiCGSTAB may stall when a linear factor (nearly) degenerates. BiCGstab({ell}) is designed to overcome this degeneration of linear factors. It generalizes BiCGSTAB and uses both the BiCG polynomial and a product of higher order factors. Still, CGS may converge faster than BiCGSTAB or BiCGstab({ell}). So instead of using a product of linear or higher order factors, it may be worthwhile to look for other polynomials. Since the BiCG polynomial is based on a three term recursion, a natural choice would be a polynomial based on another three term recursion. Possibly, a suitable choice of recursion coefficients would result in method that converges faster or as fast as CGS, but less erratic. It turns out that an algorithm for such a method can easily be formulated. One particular choice for the recursion coefficients leads to CGS. Therefore one could call this algorithm generalized CGS. Another choice for the recursion coefficients leads to BiCGSTAB. It is therefore possible to mix linear factors and some polynomial based on a three term recursion. This way one may get the best of both worlds. The authors will report on their findings.

  17. A facile strategy for the preparation of ZnS nanoparticles deposited on montmorillonite and their higher catalytic activity for rapidly colorimetric detection of H{sub 2}O{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Yanyuan; Sun, Lifang; Jiang, Yanling; Liu, Shunxiang; Chen, Mingxing; Chen, Miaomiao; Ding, Yanan; Liu, Qingyun, E-mail: qyliu@sdust.edu.cn

    2016-10-01

    In this paper, ZnS nanoparticles deposited on montmorillonite (ZnS-MMT) were prepared by a facile method at room temperature and characterized by powder X-ray diffraction (XRD), Energy-dispersive X-ray Detector (EDX) and transmission electron microscope (TEM), respectively. Significantly, the as-prepared ZnS-MMT nanocomposites have been proven to possess intrinsic peroxidase-like activity that can rapidly catalyze the reaction of peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H{sub 2}O{sub 2} and produce a blue color product in less than 30 seconds, which provides a sensitive colorimetric sensor to detect H{sub 2}O{sub 2}. Due to the synergistic effects between montmorillonite and ZnS nanoparticles, the obtained ZnS-MMT nanocomposites exhibit higher catalytic activity than that of MMT or ZnS alone. The catalytic behaviors of the ZnS-MMT nanocomposites showed a typical Michaelis–Menten kinetics. The catalytic activity and the catalytic mechanism were investigated using the procedures of steady-state kinetics and hydroxyl radical detection. ESR data revealed that the peroxidase-like activity of ZnS-MMT originated from the generation of ·OH radicals. - Highlights: • ZnS nanocomposites deposited on MMT was synthesized by a facile one step method. • MMT-ZnS nanocomposites possess excellent intrinsic peroxidase-like activity and show highly catalytic activity. • A sensitive colorimetric sensor for H{sub 2}O{sub 2} is provided based on MMT-ZnS nanocomposites. • The catalytic mechanism is from the generation of hydroxyl radical (·OH) decomposed from H{sub 2}O{sub 2}.

  18. The effect of water uptake gradient in membrane electrode assembly on fuel cell performance

    Energy Technology Data Exchange (ETDEWEB)

    Fujita, H., E-mail: hajime.phy@gmail.co [Research Institute for Science Engineering, Waseda University, 103, R.J.Shillman Hall, 3-14-9, Okubo, Shinjuku, Tokyo 169-0072 (Japan); Shiraki, F.; Oshima, Y.; Tatsumi, T.; Yoshikawa, T.; Sasaki, T. [Research Institute for Science Engineering, Waseda University, 103, R.J.Shillman Hall, 3-14-9, Okubo, Shinjuku, Tokyo 169-0072 (Japan); Oshima, A. [Institute for Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Washio, M. [Research Institute for Science Engineering, Waseda University, 103, R.J.Shillman Hall, 3-14-9, Okubo, Shinjuku, Tokyo 169-0072 (Japan)

    2011-02-15

    Novel proton exchange membranes (PEMs) with functionally gradient ionic sites were fabricated utilizing low energy electron beam (EB) irradiations. The low energy electron beam irradiation to polymer membranes possessed the property of gradient energy deposition in the membrane thickness direction. In the process of EB grafting of styrene onto base films, selective ranges of the gradient energy deposition were used. Micro FT-IR spectra showed that the simulated energy deposition of EB irradiation to base polymer membranes in the thickness direction corresponded to the amount of styrene grafted onto EB-irradiated films. After sulfonation, a functionally gradient ionic site PEM (gradient-PEM) was prepared, corresponding to EB depth-dose profile. The functionally gradients of ionic sites in the gradient-PEM and flat-PEM were evaluated with XPS and SEM-EDX. The results of XPS and SEM-EDX suggest that the prepared gradient-PEM had a gradient sulfonated acid groups. In addition, the polarization performance of MEA based on gradient-PEM was improved in high current density. It was thought that water uptake gradient could have a function to prevent flooding in the MEA during FC operation. Thus, the functionally gradient-PEMs could be a promising solution to manage the water behavior in MEA.

  19. Evaluation of the MicroSEQ™ Salmonella spp. Detection Kit with the PrepSEQ™ Rapid Spin Sample Preparation Kit for Detection of Salmonella spp. in Dry Pet Food.

    Science.gov (United States)

    Cloke, Jonathan; Flannery, Jonathan; Bastin, Benjamin; Bird, Patrick; Crowley, Erin Sutphin; Benzinger, M Joseph; Agin, James R; Goins, David; Chen, Yi

    2016-01-01

    A method modification validation study was conducted to validate the Applied Biosystems MicroSEQ™ Salmonella spp. Detection Kit for the detection of Salmonella spp. in 375 g samples of dried pet food. The MicroSEQ assay protocol, using the Applied Biosystems PrepSEQ™ Rapid Spin DNA Sample Preparation Kit, was compared to the reference method detailed in the U.S Food and Drug Administration (FDA) Bacteriological Analytical Manual (BAM; Chapter 5, Salmonella) for detection of Salmonella spp. For each method, 20 replicates were analyzed at a low contamination level of 0.2-2 CFU/test portion, five replicates were analyzed at a high level of contamination of 2-5 CFU/test portion, and five control replicates were also analyzed at 0 CFU/test portion (uninoculated). Statistical analysis was conducted using the Probability of Detection statistical test to determine the ability of the MicroSEQ Salmonella spp. Detection Kit to detect Salmonella from 375 g samples of dried pet food in comparison to the FDA-BAM reference method. The results demonstrated that the MicroSEQ Salmonella spp. Detection Kit was able to accurately detect Salmonella spp. present in dry pet food after an enrichment time of 20 h.

  20. Preparation and soldering test for rapid solidification Sn-Ag-Cu solder alloy%快速凝固型Sn-Ag-Cu系钎料合金制备及钎焊工艺试验

    Institute of Scientific and Technical Information of China (English)

    李攀; 张鑫; 刘治军; 高广东; 熊毅

    2012-01-01

    采用单辊法制备了快速凝固型Sn2.5Ag0.7Cu钎料合金,在对其进行XRD检测、熔化特性测定和钎焊工艺试验后,对一定钎焊工艺条件下钎焊接头的力学性能和显微组织进行了测试分析,结果表明:所制备的钎料合金的熔化特性和钎焊接头力学性能满足要求,钎缝-母材界面上金属间化合物呈不均匀分布,且朝向钎焊缝中心生长.%Rapid solidification Sn2.5Ag0.7Cu solder alloy was prepared by using single-roller method, after XRD-test and testing the melting property and soldering procedure, the mechanical properties and microstructure of the joints under given soldering conditions were tested and analyzed. The results showed that the melting property of the solder alloy and mechanical properties of the joint were satisfactory. The IMC located at the solder-parent metal interface had an uneven distribution, and they grew toward the center of the solder seam.

  1. Preparation of Micro-scale Particulates of Pioglitazone Hydrochloride by Rapid Precipitation without Surfactants%无表面活性剂快速沉淀法制备盐酸吡格列酮微粉

    Institute of Scientific and Technical Information of China (English)

    于世华; 陈萍; 程振玉; 连丽丽

    2014-01-01

    本研究在不加入表面活性剂条件下采用快速沉淀法制备盐酸吡格列微粉,分别利用扫描电镜( SEM )、X射线衍射( XRD)、红外光谱分析( FT-IR)等分析方法对原药及产品的性质进行了表征。SEM分析表明,使用快速沉淀法制备的盐酸吡格列酮超微粉尺寸降低,粒度分布均匀,FT-IR、XRD分析表明,微粉化前后药物的化学结构并未发生改变,粒度明显减小,结晶度明显降低。%The microsized pioglitazone hydrochloride(PH) was prepared via the rapid precipitation proces without surfactant. The microsized pioglitazone hydrochloride and the raw drug were well characterized by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), fourier transform infrared spectrometry (FT-IR). The study indicated that after micronization, the particle size decreased, the range of particle size distribution became well through SEM. FT-IR and XRD analysis indicated the particle size decreased and ccrystallinity decreased during the process and no change in chemical group structure.

  2. Rapid Concentration of Nanoparticles with DC Dielectrophoresis in Focused Electric Fields

    Directory of Open Access Journals (Sweden)

    Chen Dafeng

    2009-01-01

    Full Text Available Abstract We report a microfluidic device for rapid and efficient concentration of micro/nanoparticles with direct current dielectrophoresis (DC DEP. The concentrator is composed of a series of microchannels constructed with PDMS-insulating microstructures for efficiently focusing the electric field in the flow direction to provide high field strength and gradient. The location of the trapped and concentrated particles depends on the strength of the electric field applied. Both ‘streaming DEP’ and ‘trapping DEP’ simultaneously take place within the concentrator at different regions. The former occurs upstream and is responsible for continuous transport of the particles, whereas the latter occurs downstream and rapidly traps the particles delivered from upstream. The performance of the device is demonstrated by successfully concentrating fluorescent nanoparticles. The described microfluidic concentrator can be implemented in applications where rapid concentration of targets is needed such as concentrating cells for sample preparation and concentrating molecular biomarkers for detection.

  3. Toxoplasma gondii: a rapid method for the isolation of pure tachyzoites: preliminary characterization of its genome

    Directory of Open Access Journals (Sweden)

    Juan Carlos Garberi

    1990-12-01

    Full Text Available A rapid and simple technique for the purification of Toxoplasma gondii tachyzoites was developed. Highly purified parasites were obtained from the peritoneal exudates of infected mice by means of two consecutive discontinous sucrose gradients run at low speed (10,000xg, 30 min. Parasites obtained by this method conserved its biological activity. Hybridizations tudies with DNA from healthy mice and from purified tachyzoites preparations demonstrated that Toxoplasma gondii tachyzoites DNA could be obtained with better than 90 per cents purity. Preliminary studies with DNA endonucleases showed the presence in the tachyzoites genome of highly repetitives sequences.

  4. Sobolev gradients and differential equations

    CERN Document Server

    Neuberger, J W

    2010-01-01

    A Sobolev gradient of a real-valued functional on a Hilbert space is a gradient of that functional taken relative to an underlying Sobolev norm. This book shows how descent methods using such gradients allow a unified treatment of a wide variety of problems in differential equations. For discrete versions of partial differential equations, corresponding Sobolev gradients are seen to be vastly more efficient than ordinary gradients. In fact, descent methods with these gradients generally scale linearly with the number of grid points, in sharp contrast with the use of ordinary gradients. Aside from the first edition of this work, this is the only known account of Sobolev gradients in book form. Most of the applications in this book have emerged since the first edition was published some twelve years ago. What remains of the first edition has been extensively revised. There are a number of plots of results from calculations and a sample MatLab code is included for a simple problem. Those working through a fair p...

  5. Around the laboratories: Dubna: Physics results and progress on bubble chamber techniques; Stanford (SLAC): Operation of a very rapid cycling bubble chamber; Daresbury: Photographs of visitors to the Laboratory; Argonne: Charge exchange injection tests into the ZGS in preparation for a proposed Booster

    CERN Multimedia

    1969-01-01

    Around the laboratories: Dubna: Physics results and progress on bubble chamber techniques; Stanford (SLAC): Operation of a very rapid cycling bubble chamber; Daresbury: Photographs of visitors to the Laboratory; Argonne: Charge exchange injection tests into the ZGS in preparation for a proposed Booster

  6. Gradient zone boundary control in salt gradient solar ponds

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R. (Downers Grove, IL)

    1984-01-01

    A method and apparatus for suppressing zone boundary migration in a salt gradient solar pond includes extending perforated membranes across the pond at the boundaries, between the convective and non-convective zones, the perforations being small enough in size to prevent individual turbulence disturbances from penetrating the hole, but being large enough to allow easy molecular diffusion of salt thereby preventing the formation of convective zones in the gradient layer. The total area of the perforations is a sizable fraction of the membrane area to allow sufficient salt diffusion while preventing turbulent entrainment into the gradient zone.

  7. Rapid collection and identification of a novel component from Clausena lansium Skeels leaves by means of three-dimensional preparative gas chromatography and nuclear magnetic resonance/infrared/mass spectrometric analysis

    Energy Technology Data Exchange (ETDEWEB)

    Sciarrone, Danilo [Dipartimento di Scienze del Farmaco e dei Prodotti per la Salute, University of Messina, Viale Annunziata, 98168, Messina (Italy); Chromaleont s.r.l. A start-up of the University of Messina, c/o University of Messina, Viale Annunziata, 98168 Messina (Italy); Pantò, Sebastiano [Dipartimento di Scienze del Farmaco e dei Prodotti per la Salute, University of Messina, Viale Annunziata, 98168, Messina (Italy); Rotondo, Archimede [Dipartimento di Scienze Chimiche, Università di Messina, Via D’Alcontres 31, 98166 Messina (Italy); Tedone, Laura; Tranchida, Peter Quinto [Dipartimento di Scienze del Farmaco e dei Prodotti per la Salute, University of Messina, Viale Annunziata, 98168, Messina (Italy); Dugo, Paola [Dipartimento di Scienze del Farmaco e dei Prodotti per la Salute, University of Messina, Viale Annunziata, 98168, Messina (Italy); Centro Integrato di Ricerca (C.I.R.), Università Campus Bio-Medico, Via Álvaro del Portillo, 21 - 00128 Roma (Italy); Mondello, Luigi, E-mail: lmondello@unime.it [Dipartimento di Scienze del Farmaco e dei Prodotti per la Salute, University of Messina, Viale Annunziata, 98168, Messina (Italy); Centro Integrato di Ricerca (C.I.R.), Università Campus Bio-Medico, Via Álvaro del Portillo, 21 - 00128 Roma (Italy)

    2013-06-27

    Graphical abstract: -- Highlights: •A recently-developed three-dimensional prep-GC system has been applied to wampee essential oil. •The prep GC system enables the rapid collection of pure compounds from complex samples. •An isolated unknown solute was identified through NMR, IR and MS data. •The structure of an oxygenated sesquiterpene is here reported for the first time. -- Abstract: The present research reports the use of a three-dimensional preparative gas chromatography (prep GC) system, equipped with three Deans-switch devices and 5%diphenyl/wax/mid-polarity ionic liquid stationary phases, for the isolation of volatile components from a complex natural source, namely wampee essential oil (derived from Clausena lansium Skeels leaves). Collection was performed by using a simple and effective lab-constructed trapping device. Initially, an unknown (and abundant) wampee oil constituent was erroneously identified as α-sinensal, through an MS database search (a low similarity match was attained), performed after a GC-quadMS experiment., The unknown compound was then the isolated by using the novel prep GC system, in a highly pure form (at the mg level), and was correctly identified by using nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR) and mass spectrometry (MS). Both FTIR and MS data were used to confirm the NMR information. The name given to the molecule was (2E,6E)-2-methyl-6-(4-methylcyclohex-3-enylidene)hept-2-enal. The results herein described will demonstrate the need for a high-resolution GC step, prior to analyte collection, in the prep GC analysis of complex samples.

  8. Application of microfluidic chip to realize controllable pH gradient

    Institute of Scientific and Technical Information of China (English)

    LUO Chunxiong; SUN Manhui; XU Luping; ZHANG Zhiling; C. Crozatier; CHEN Yong; JI Hang

    2005-01-01

    A kind of PH gradient microfluidic chips through soft-lithography microfabrication for isoelectric focusing (IEF) and high performance liquid chromatography (HPLC) is introduced here. These pH gradient chips have the advantages such as easy fabrication, controllable pH range and precision, isoelectric focusing and separation at the same time, low voltage for isoelectric focusing, and time stable pH gradient. This method has potential application to sample preparation, separation and analysis of microfluidic chips.

  9. Systematics in Metallicity Gradient Measurements I : Angular Resolution, Signal-to-Noise and Annuli Binning

    CERN Document Server

    Yuan, T -T; Rich, J

    2013-01-01

    With the rapid progress in metallicity gradient studies at high-redshift, it is imperative that we thoroughly understand the systematics in these measurements. This work investigates how the [NII]/Halpha ratio based metallicity gradients change with angular resolution, signal-to-noise (S/N), and annular binning parameters. Two approaches are used: 1. We downgrade the high angular resolution integral-field data of a gravitationally lensed galaxy and re-derive the metallicity gradients at different angular resolution; 2. We simulate high-redshift integral field spectroscopy (IFS) observations under different angular resolution and S/N conditions using a local galaxy with a known gradient. We find that the measured metallicity gradient changes systematically with angular resolution and annular binning. Seeing-limited observations produce significantly flatter gradients than higher angular resolution observations. There is a critical angular resolution limit beyond which the measured metallicity gradient is subst...

  10. Sobolev gradients and differential equations

    CERN Document Server

    Neuberger, John William

    1997-01-01

    A Sobolev gradient of a real-valued functional is a gradient of that functional taken relative to the underlying Sobolev norm. This book shows how descent methods using such gradients allow a unified treatment of a wide variety of problems in differential equations. Equal emphasis is placed on numerical and theoretical matters. Several concrete applications are made to illustrate the method. These applications include (1) Ginzburg-Landau functionals of superconductivity, (2) problems of transonic flow in which type depends locally on nonlinearities, and (3) minimal surface problems. Sobolev gradient constructions rely on a study of orthogonal projections onto graphs of closed densely defined linear transformations from one Hilbert space to another. These developments use work of Weyl, von Neumann and Beurling.

  11. Conjugate Gradient with Subspace Optimization

    CERN Document Server

    Karimi, Sahar

    2012-01-01

    In this paper we present a variant of the conjugate gradient (CG) algorithm in which we invoke a subspace minimization subproblem on each iteration. We call this algorithm CGSO for "conjugate gradient with subspace optimization". It is related to earlier work by Nemirovsky and Yudin. We apply the algorithm to solve unconstrained strictly convex problems. As with other CG algorithms, the update step on each iteration is a linear combination of the last gradient and last update. Unlike some other conjugate gradient methods, our algorithm attains a theoretical complexity bound of $O(\\sqrt{L/l} \\log(1/\\epsilon))$, where the ratio $L/l$ characterizes the strong convexity of the objective function. In practice, CGSO competes with other CG-type algorithms by incorporating some second order information in each iteration.

  12. Flame Propagation Through Concentration Gradient

    Institute of Scientific and Technical Information of China (English)

    JunyaIINO; MitsuakiTANABE; 等

    2000-01-01

    The experiment was carried out in homogeneous propane-air mixture and in several concentration gradient of mixture.Igniter is put on the upper side of the combustion chamber,In concentration gradient experiment.ixture was ignited from lean side.An experimental study was conducted in a combustion chamber.The combustion chamber has glass windows for optical measurements at any side.For the measurement of distribution of fuel concentration,infraed absorption method using 3.39μm He-Ne laser was used,and for the observation of proagating flams,Schlieren method was employed.As a measurment result of flame propagation velocity and flammable limit,for a mixture of an identical local equivalence ratio.flame propagation velocity in concentration gradient is faster than that in homogeneous mixture,and rich flammable limit in concentration gradient shows a tendency to be higher than that in homogeneous mixture.

  13. ADHESION AND SPREADING OF HUMAN SKIN FIBROBLASTS ON PHYSICOCHEMICALLY CHARACTERIZED GRADIENT SURFACES

    NARCIS (Netherlands)

    RUARDY, TG; SCHAKENRAAD, JM; VANDERMEI, HC; BUSSCHER, HJ

    1995-01-01

    In this study, adhesion and spreading of human skin fibroblasts on gradient surfaces of dichlorodimethylsilane (DDS) coupled to glass was investigated. Gradient surfaces were prepared by the diffusion technique and characterized by the Wilhelmy plate technique for their wettability and by scanning x

  14. Long pendulums in gravitational gradients

    Energy Technology Data Exchange (ETDEWEB)

    Suits, B H [Physics Department, Michigan Technological University, Houghton, MI 49931 (United States)

    2006-03-01

    Previous results for long pendulums above a spherical Earth are generalized for arbitrary non-uniform gravitational fields in the limit of small oscillation. As is the case for the previous results, gravitational gradients are multiplied by the length of the string even though the string is assumed massless. The effect is shown to arise from the constraint on the motion imposed by the string. The significance of these results for real gradients is discussed. (letters and comments)

  15. Low-gradient aortic stenosis.

    Science.gov (United States)

    Clavel, Marie-Annick; Magne, Julien; Pibarot, Philippe

    2016-09-07

    An important proportion of patients with aortic stenosis (AS) have a 'low-gradient' AS, i.e. a small aortic valve area (AVA <1.0 cm(2)) consistent with severe AS but a low mean transvalvular gradient (<40 mmHg) consistent with non-severe AS. The management of this subset of patients is particularly challenging because the AVA-gradient discrepancy raises uncertainty about the actual stenosis severity and thus about the indication for aortic valve replacement (AVR) if the patient has symptoms and/or left ventricular (LV) systolic dysfunction. The most frequent cause of low-gradient (LG) AS is the presence of a low LV outflow state, which may occur with reduced left ventricular ejection fraction (LVEF), i.e. classical low-flow, low-gradient (LF-LG), or preserved LVEF, i.e. paradoxical LF-LG. Furthermore, a substantial proportion of patients with AS may have a normal-flow, low-gradient (NF-LG) AS: i.e. a small AVA-low-gradient combination but with a normal flow. One of the most important clinical challenges in these three categories of patients with LG AS (classical LF-LG, paradoxical LF-LG, and NF-LG) is to differentiate a true-severe AS that generally benefits from AVR vs. a pseudo-severe AS that should be managed conservatively. A low-dose dobutamine stress echocardiography may be used for this purpose in patients with classical LF-LG AS, whereas aortic valve calcium scoring by multi-detector computed tomography is the preferred modality in those with paradoxical LF-LG or NF-LG AS. Although patients with LF-LG severe AS have worse outcomes than those with high-gradient AS following AVR, they nonetheless display an important survival benefit with this intervention. Some studies suggest that transcatheter AVR may be superior to surgical AVR in patients with LF-LG AS.

  16. Graded/Gradient Porous Biomaterials

    Directory of Open Access Journals (Sweden)

    Xigeng Miao

    2009-12-01

    Full Text Available Biomaterials include bioceramics, biometals, biopolymers and biocomposites and they play important roles in the replacement and regeneration of human tissues. However, dense bioceramics and dense biometals pose the problem of stress shielding due to their high Young’s moduli compared to those of bones. On the other hand, porous biomaterials exhibit the potential of bone ingrowth, which will depend on porous parameters such as pore size, pore interconnectivity, and porosity. Unfortunately, a highly porous biomaterial results in poor mechanical properties. To optimise the mechanical and the biological properties, porous biomaterials with graded/gradient porosity, pores size, and/or composition have been developed. Graded/gradient porous biomaterials have many advantages over graded/gradient dense biomaterials and uniform or homogenous porous biomaterials. The internal pore surfaces of graded/gradient porous biomaterials can be modified with organic, inorganic, or biological coatings and the internal pores themselves can also be filled with biocompatible and biodegradable materials or living cells. However, graded/gradient porous biomaterials are generally more difficult to fabricate than uniform or homogenous porous biomaterials. With the development of cost-effective processing techniques, graded/gradient porous biomaterials can find wide applications in bone defect filling, implant fixation, bone replacement, drug delivery, and tissue engineering.

  17. Prostate treatments, 1MRT o RapidArc; Tratamiento de prostata, IMART o RapidArc?

    Energy Technology Data Exchange (ETDEWEB)

    Castro novais, J.; Ruiz Maqueda, S.; Pardo Perez, E.; Molina Lopez, M. Y.; Cerro Penalver, E.

    2015-07-01

    Techniques that modulate the dose (as IMRT or RapidArcTM) improve dose homogeneity within the target volume decreasing the dose in healthy organs. The aim of this work is to study the dosimetric differences in prostate radiotherapy treatments with IMRT and RapidArcTM. The results of the 109 patients studied show that plans to RapidArcTM have better coverage, compliance and dose gradient outside the target volume. (Author)

  18. Composition Gradient Hard Coatings by Arc Ion Plating

    Institute of Scientific and Technical Information of China (English)

    CHENJun; LINGuo-qiang; WANGFu-gang

    2004-01-01

    Arc Ion Plating can be used to synthesize multi-component composition gradient hard coatings by adjusting arc currents of metal targets. The present work aims at a comprehensive description of such a technique. The examples of TiAl multi-layer alloy coatings and (Ti,M) N composition-gradient films were taken (M representing Zr, Nb etc.) for the purpose of explaining the working process and evaluating practical effects. The results show that this technique has the advantages of easy manipulation, rapid deposition, and wide composition range.

  19. Gradient distribution of radial structure of PAN-based carbon fiber treated by high temperature

    Institute of Scientific and Technical Information of China (English)

    Haitao Wang; Yu Wang; Ting Li; Shuai Wu; Lianghua Xu

    2014-01-01

    High-performance graphite fibers were prepared and analyzed. The gradient distribution of radial structure of PAN-based carbon fibers was characterized by two different Raman test methods (incident laser beam perpendicular to and parallel to the fiber axis) and studied by the distribution of graphitization degree. Meanwhile difference between the two Raman test methods was used to describe the orientation of the graphite crystallite along the fiber axis. The results showed that the radial structure of PAN-based carbon fiber presented different gradient distribution states at different heat treatment temperatures, and the graphitization degree in the skin region changed more rapidly compared with the core region since the skin region was more affected by temperature which resulted in the obvious difference between skin and core structures. The difference of graphitization degree (Δg) characterized by two different Raman test methods increased with heat treatment temperature, indicating that the high temperature treatment (HTT) promoted further stacking of graphite crystallite, and the orientation degree of the graphite crystallite along the fiber axis was continuously increased.

  20. Amine-phenyl multi-component gradient stationary phases.

    Science.gov (United States)

    Dewoolkar, Veeren C; Kannan, Balamurali; Ashraf, Kayesh M; Higgins, Daniel A; Collinson, Maryanne M

    2015-09-04

    Continuous multi-component gradients in amine and phenyl groups were fabricated using controlled rate infusion (CRI). Solutions prepared from either 3-aminopropyltriethoxysilane (APTEOS) or phenyltrimethoxysilane (PTMOS) were infused, in a sequential fashion, at a controlled rate into an empty graduated cylinder housing a vertically aligned thin layer chromatography (TLC) plate. The hydrolyzed precursors reacted with an abundance of silanol (SiOH) groups on the TLC plates, covalently attaching the functionalized silane to its surface. The extent of modification by phenyl and amine was determined by the kinetics of each reaction and the exposure time at each point along the TLC plate. The local concentrations of phenyl and amine were measured using diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy, respectively. The profile of the multi-component gradients strongly depended on the order of infusion, the direction of the gradient and the presence of available surface silanol groups. A slightly higher amount of phenyl can be deposited on the TLC plate by first modifying its surface with amine groups as they serve as a catalyst, enhancing condensation. Separation of water- and fat-soluble vitamins and the control of retention factors were demonstrated on the multi-component gradient TLC plates. Uniformly modified and single-component TLC plates gave different separations compared to the multi-component gradient plates. The retention factors of the individual vitamins depended on the order of surface modification, the spotting end, and whether the multi-component gradients align or oppose each other.

  1. 快速成型技术制备仿生主动脉弓模型的研究%Preliminary study on rapid prototyping to prepare biomimetic model of aortic arch

    Institute of Scientific and Technical Information of China (English)

    陈鹏飞; 严中亚; 申运华; 陈向东; 邓克学

    2015-01-01

    目的 创建与人体解剖结构一致的仿真主动脉弓三维快速成型模型,探讨其对促进规划和执行主动脉弓外科手术的帮助,为构建个体化人工血管支架及3D打印生物组织或器官进行前期准备.方法 对正常成年男性进行胸部CT扫描,获得该男子主动脉弓原始CT数据(DICOM),通过Mimics 10.01软件对DICOM数据处理,分割出主动脉弓的区域,计算主动脉弓三维立体模型,导出三维模型数据文件(STL文件),最后通过3D打印机打印出主动脉弓三维模型.结果 基于CT获得的胸部解剖结构的数据,通过MIMICS 10.01软件进行处理并导出STL格式文件后,可直接用3D打印机打印出与人体主动脉弓解剖结构基本一致的主动脉弓模型(比例1∶1).结论 快速成型技术制备的主动脉弓模型对手术规划有临床意义,有助于构建个体化人工血管支架及3D打印生物组织或器官.%Objective To create an anatomical correct 3D rapid prototyping (RP) model for a volunteer' s aortic arch and investigate the significance of aortic arch model for surgical planning.To make the early preparations for the mannufacture of individualize artificial vascular stents and 3D printing with biological tissue or organ.Methods Based on the extracted 3D contour image from volunteer' s chest CT data,the custom-made artificial aortic arch was designed with mimics 10.01 software and form 3D printing STL file.And then a aortic arch model was printed out by 3D printer.Results The data acquired by CT scanner can be rapidly prototyped after being edited with Mimics 10.01 software and directly used by 3D printing system to construct a aortic arch model (1∶1).Conclusion The artificial 3D aortic arch model has significance in surgical planning and great help for the mannufacture of individualize artificial vascular stents and 3D printing with biological tissue or organ.

  2. Reproducible isolation of type II pneumocytes from fetal and adult rat lung using nycodenz density gradients.

    Science.gov (United States)

    Viscardi, R M; Ullsperger, S; Resau, J H

    1992-01-01

    Isolating fresh, relatively pure type II pneumocytes from the lung, particularly of fetal origin, is a difficult process. Separation by buoyant density gradient centrifugation has been used successfully to isolate adult type II cells. There is concern, however, that Percoll, a gradient medium that is commonly used for type II cell isolation, may be toxic to cells. We evaluated a new gradient medium, Nycodenz, that is (1) a true solution, (2) transparent, (3) not metabolized by cells, and (4) nontoxic to cells. Type II pneumocytes were isolated from 19- and 21-day gestation fetal and adult rat lung by elastase digestion and separated on preformed isotonic Nycodenz gradients (2 mL each of 27.6, 20.7, 13.8, and 4.6 (w/v) solutions). Type II pneumocytes were recovered from the density range 1.057-1.061 and identified by binding of FITC-conjugated and gold-complexed Maclura pomifera lectin. Cells derived from 19-day fetal lung contained abundant glycogen and reacted with a monoclonal antibody to the cytokeratins 8 and 18, which are markers of the fetal type II cell. Adult type II cells reacted with antibodies to cytokeratins 8, 18, and 19. Type II cell purity was 79.7 +/- 2.4%, 83.8 +/- 2.8%, and 82.6 +/- 1.8% (means +/- SEM) for 19- and 21-day gestation fetal and adult lung preparations, respectively. Cell viability was greater than 95%. The final cell yield for adult preparations was 17.8 +/- 2.7 x 10(6)/rat (means +/- SEM). To determine if the freshly isolated type II pneumocytes were functionally active, the incorporation of [3H]choline into phosphatidylcholine was measured. The percent saturation of phosphatidylcholine was high for both populations of freshly isolated cells. However, adult type II pneumocytes incorporated [3H]choline into phosphatidylcholine more rapidly than 21-day gestation fetal cells (5.97 x 10(-3) dpm/10(6) cells/h vs. 0.32 x 10(-3) dpm/10(6) cells/h, P less than .005). We have demonstrated that, using the Nycodenz isolation method, it is

  3. Monolithic polymer layer with gradient of hydrophobicity for separation of peptides using two-dimensional thin layer chromatography and MALDI-TOF-MS detection.

    Science.gov (United States)

    Urbanova, Iva; Svec, Frantisek

    2011-08-01

    Superhydrophobic monolithic porous polymer layers supported onto glass plates with a gradient of hydrophobicity have been prepared and used for 2-D thin layer chromatography of peptides. The 50 μm-thin poly(glycidyl methacrylate-co-ethylene dimethacrylate) layers prepared using UV-initiated polymerization in a simple mold were first hydrolyzed using dilute sulfuric acid and then hydrophilized via two-step grafting of poly(ethylene glycol) methacrylate to obtain superhydrophilic plates. The hydrophobicity was then formed by photografting of lauryl methacrylate. The exposure to UV light that initiates photografting was spatially controlled using moving shutter that enabled forming of the diagonal gradient of hydrophobicity. This new concept enables the solutes to encounter the gradient for each of the two sequential developments. Practical application of our novel plates was demonstrated with a rapid 2-D separation of a mixture of model peptides gly-tyr, val-tyr-val, leucine enkephalin, and oxytocin in dual reversed-phase mode using different mobile phases in each direction. Detection of fluorescent-labeled peptides was achieved through UV light visualization while separation of native leucine enkephalin and oxytocin was monitored directly using MALDI mass spectrometry. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Radiation emitted by transverse-gradient undulators

    Science.gov (United States)

    Bernhard, Axel; Braun, Nils; Rodríguez, Verónica Afonso; Peiffer, Peter; Rossmanith, Robert; Widmann, Christina; Scheer, Michael

    2016-09-01

    Conventional undulators are used in synchrotron light sources to produce radiation with a narrow relative spectral width as compared to bending magnets or wigglers. The spectral width of the radiation produced by conventional undulators is determined by the number of undulator periods and by the energy spread and emittance of the electron beam. In more compact electron sources like for instance laser plasma accelerators the energy spread becomes the dominating factor. Due to this effect these electron sources cannot in general be used for high-gain free electron lasers (FELs). In order to overcome this limitation, modified undulator schemes, so-called transverse gradient undulators (TGUs), were proposed and a first superconducting TGU was built at Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany. In this paper simulations of the expected synchrotron radiation spectral distribution are presented. An experimental test with that device is under preparation at the laser wakefield accelerator at the JETI laser at the University of Jena, Germany.

  5. Gradient expansion for anisotropic hydrodynamics

    Science.gov (United States)

    Florkowski, Wojciech; Ryblewski, Radoslaw; Spaliński, Michał

    2016-12-01

    We compute the gradient expansion for anisotropic hydrodynamics. The results are compared with the corresponding expansion of the underlying kinetic-theory model with the collision term treated in the relaxation time approximation. We find that a recent formulation of anisotropic hydrodynamics based on an anisotropic matching principle yields the first three terms of the gradient expansion in agreement with those obtained for the kinetic theory. This gives further support for this particular hydrodynamic model as a good approximation of the kinetic-theory approach. We further find that the gradient expansion of anisotropic hydrodynamics is an asymptotic series, and the singularities of the analytic continuation of its Borel transform indicate the presence of nonhydrodynamic modes.

  6. Gradient expansion for anisotropic hydrodynamics

    CERN Document Server

    Florkowski, Wojciech; Spaliński, Michał

    2016-01-01

    We compute the gradient expansion for anisotropic hydrodynamics. The results are compared with the corresponding expansion of the underlying kinetic-theory model with the collision term treated in the relaxation time approximation. We find that a recent formulation of anisotropic hydrodynamics based on an anisotropic matching principle yields the first three terms of the gradient expansion in agreement with those obtained for the kinetic theory. This gives further support for this particular hydrodynamic model as a good approximation of the kinetic-theory approach. We further find that the gradient expansion of anisotropic hydrodynamics is an asymptotic series, and the singularities of the analytic continuation of its Borel transform indicate the presence of non-hydrodynamic modes.

  7. Bond Growth under Temperature Gradient.

    Directory of Open Access Journals (Sweden)

    P.K. Satyawali

    1999-12-01

    Full Text Available Grain and bond growth for dry snow are determined by the distribution of temperature andtemperature gradient in the snow matrix. From the standpoint of particle approach and based oncubic packing structure, a bond growth model has been developed for TG metamorphism. The paper.highlights the importance of bond formation and its effect on snow viscosity and finally on the rateof settlement. This is very important for developing a numerical snow pack model if microstructureis considered to be a basic parameter. A few experiments have been carried out to validate bond formation under temperature gradient.

  8. Probing the kinetic performance limits for ion chromatography. II. Gradient conditions for small ions.

    Science.gov (United States)

    Causon, Tim J; Hilder, Emily F; Shellie, Robert A; Haddad, Paul R

    2010-07-30

    A gradient kinetic plot method is used for theoretical characterisation of the performance of polymeric particulate anion exchange columns for gradient separations of small inorganic anions. The method employed requires only information obtained from a series of isocratic column performance measurements and in silico predictions of retention time and peak width under gradient conditions. Results obtained under practically constrained conditions provide parameters for the generation of high peak capacities and rapid peak production for fast analysis to be determined. Using this prediction method, a maximum theoretical peak capacity of 84 could be used to achieve separation of 26 components using a 120min gradient (R(s)>1). This approach provides a highly convenient tool for development of both mono- and multidimensional ion chromatography (IC) methodologies as it yields comprehensive understanding of the influence of gradient slope, analysis time, column length and temperature upon kinetically optimised gradient performance.

  9. The geomagnetic field gradient tensor

    DEFF Research Database (Denmark)

    Kotsiaros, Stavros; Olsen, Nils

    2012-01-01

    We develop the general mathematical basis for space magnetic gradiometry in spherical coordinates. The magnetic gradient tensor is a second rank tensor consisting of 3 × 3 = 9 spatial derivatives. Since the geomagnetic field vector B is always solenoidal (∇ · B = 0) there are only eight independe...... of the small-scale structure of the Earth’s lithospheric field....

  10. Surface gradients under electrochemical control

    NARCIS (Netherlands)

    Krabbenborg, Sven Olle

    2014-01-01

    Gradients are systems in which the physicochemical properties of a solution and/or surface change gradually in space and/or time. They are used for a myriad of technological and biological applications, for example for high-throughput screening, or for the investigation of biological systems. The de

  11. Compositional gradients in Gramineae genes

    DEFF Research Database (Denmark)

    Wong, Gane Ka-Shu; Wang, Jun; Tao, Lin

    2002-01-01

    In this study, we describe a property of Gramineae genes, and perhaps all monocot genes, that is not observed in eudicot genes. Along the direction of transcription, beginning at the junction of the 5'-UTR and the coding region, there are gradients in GC content, codon usage, and amino-acid usage...

  12. GOCE level 2 gravity gradients

    NARCIS (Netherlands)

    Bouman, J.; Fiorot, S.; Fuchs, M.; Gruber, T.; Schrama, E.J.O.; Tscherning, C.C.; Veicherts, M.; Visser, P.N.A.M.

    2011-01-01

    Two of the GOCE Level 2 products are the gravity gradients (GGs) in the Gradiometer Reference Frame (GRF) and the GGs in the Local North-Oriented Frame (LNOF). The GRF is an instrument frame and the GGs are derived from the L1b GGs. The L1b to L2 GG processing involves corrections for temporal gravi

  13. Reinforcement Learning Through Gradient Descent

    Science.gov (United States)

    1999-05-14

    Reinforcement learning is often done using parameterized function approximators to store value functions. Algorithms are typically developed for...practice of existing types of algorithms, the gradient descent approach makes it possible to create entirely new classes of reinforcement learning algorithms

  14. Sample Preparation for Bioanalytical and Pharmaceutical Analysis.

    Science.gov (United States)

    Clark, Kevin D; Zhang, Cheng; Anderson, Jared L

    2016-12-06

    Biological and pharmaceutical samples represent formidable challenges in sample preparation that hold important consequences for bioanalysis and genotoxic impurity quantification. This Feature will emphasize significant advances toward the development of rapid, sensitive, and selective sample preparation methods.

  15. Preparation and characterization of antigenic properties of ...

    African Journals Online (AJOL)

    PRECIOUS

    2009-12-15

    Dec 15, 2009 ... A rapid, simple and low cost procedure for preparing hapten-protein conjugates was developed using .... using a GS-800 Calibrated Densitometer (Bio-rad, USA). .... is to develop a method to prepare effective immunogens.

  16. Variation of hydraulic gradient in nonlinear finite strain consolidation

    Institute of Scientific and Technical Information of China (English)

    谢新宇; 黄杰卿; 王文军; 李金柱

    2014-01-01

    In the research field of ground water, hydraulic gradient is studied for decades. In the consolidation field, hydraulic gradient is yet to be investigated as an important hydraulic variable. So, the variation of hydraulic gradient in nonlinear finite strain consolidation was focused on in this work. Based on lab tests, the nonlinear compressibility and nonlinear permeability of Ningbo soft clay were obtained. Then, a strongly nonlinear governing equation was derived and it was solved with the finite element method. Afterwards, the numerical analysis was performed and it was verified with the existing experiment for Hong Kong marine clay. It can be found that the variation of hydraulic gradient is closely related to the magnitude of external load and the depth in soils. It is interesting that the absolute value of hydraulic gradient (AVHG) increases rapidly first and then decreases gradually after reaching the maximum at different depths of soils. Furthermore, the changing curves of AVHG can be roughly divided into five phases. This five-phase model can be employed to study the migration of pore water during consolidation.

  17. Rapid Detection of Pathogens

    Energy Technology Data Exchange (ETDEWEB)

    David Perlin

    2005-08-14

    Pathogen identification is a crucial first defense against bioterrorism. A major emphasis of our national biodefense strategy is to establish fast, accurate and sensitive assays for diagnosis of infectious diseases agents. Such assays will ensure early and appropriate treatment of infected patients. Rapid diagnostics can also support infection control measures, which monitor and limit the spread of infectious diseases agents. Many select agents are highly transmissible in the early stages of disease, and it is critical to identify infected patients and limit the risk to the remainder of the population and to stem potential panic in the general population. Nucleic acid-based molecular approaches for identification overcome many of the deficiencies associated with conventional culture methods by exploiting both large- and small-scale genomic differences between organisms. PCR-based amplification of highly conserved ribosomal RNA (rRNA) genes, intergenic sequences, and specific toxin genes is currently the most reliable approach for bacterial, fungal and many viral pathogenic agents. When combined with fluorescence-based oligonucleotide detection systems, this approach provides real-time, quantitative, high fidelity analysis capable of single nucleotide allelic discrimination (4). These probe systems offer rapid turn around time (<2 h) and are suitable for high throughput, automated multiplex operations that are critical for clinical diagnostic laboratories. In this pilot program, we have used molecular beacon technology invented at the Public health Research Institute to develop a new generation of molecular probes to rapidly detect important agents of infectious diseases. We have also developed protocols to rapidly extract nucleic acids from a variety of clinical specimen including and blood and tissue to for detection in the molecular assays. This work represented a cooperative research development program between the Kramer-Tyagi/Perlin labs on probe development

  18. Bacterial accumulation in viscosity gradients

    Science.gov (United States)

    Waisbord, Nicolas; Guasto, Jeffrey

    2016-11-01

    Cell motility is greatly modified by fluid rheology. In particular, the physical environments in which cells function, are often characterized by gradients of viscous biopolymers, such as mucus and extracellular matrix, which impact processes ranging from reproduction to digestion to biofilm formation. To understand how spatial heterogeneity of fluid rheology affects the motility and transport of swimming cells, we use hydrogel microfluidic devices to generate viscosity gradients in a simple, polymeric, Newtonian fluid. Using video microscopy, we characterize the random walk motility patterns of model bacteria (Bacillus subtilis), showing that both wild-type ('run-and-tumble') cells and smooth-swimming mutants accumulate in the viscous region of the fluid. Through statistical analysis of individual cell trajectories and body kinematics in both homogeneous and heterogeneous viscous environments, we discriminate passive, physical effects from active sensing processes to explain the observed cell accumulation at the ensemble level.

  19. Vertebrate pressure-gradient receivers

    DEFF Research Database (Denmark)

    Christensen-Dalsgaard, Jakob

    2011-01-01

    The eardrums of all terrestrial vertebrates (tetrapods) are connected through Eustachian tubes or interaural canals. In some of the animals, these connections create pressure-gradient directionality, an enhanced directionality by interaction of sound arriving at both sides of the eardrum and stro......The eardrums of all terrestrial vertebrates (tetrapods) are connected through Eustachian tubes or interaural canals. In some of the animals, these connections create pressure-gradient directionality, an enhanced directionality by interaction of sound arriving at both sides of the eardrum....... Recent vertebrates form a continuum from perfect interaural transmission (0 dB in a certain frequency band) and pronounced eardrum directionality (30-40 dB) in the lizards, over somewhat attenuated transmission and limited directionality in birds and frogs, to the strongly attenuated interaural...

  20. Computational Strain Gradient Crystal Plasticity

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Kysar, Jeffrey W.

    2011-01-01

    A model for strain gradient crystal visco-plasticity is formulated along the lines proposed by Fleck andWillis (2009) for isotropic plasticity. Size-effects are included in the model due to the addition of gradient terms in both the free energy as well as through a dissipation potential. A finite...... element solution method is presented, which delivers the slip-rate field and the velocity-field based on two minimum principles. Some plane deformation problems relevant for certain specific orientations of a face centered cubic crystal under plane loading conditions are studied, and effective in......-plane parameters are developed based on the crystallographic properties of the material. The problem of cyclic shear of a single crystal between rigid platens is studied as well as void growth of a cylindrical void....

  1. Biomimetic Gradient Index (GRIN) Lenses

    Science.gov (United States)

    2006-01-01

    optics include single lenses inspired by cephalopod (octopus) eyes and a three-lens, wide field of view, optical system for a surveillance sensor...camera. Details are easily resolv- able with the polymer lens. This lens system was installed on an Evolution unmanned aerial vehicle (UAV) with a...lens system was installed in an NRL Evolution UAV and used to record video images at a height of up to 1000 ft. The index gradients in the polymer

  2. Multilayer coating for high gradients

    CERN Document Server

    Kubo, Takayuki

    2016-01-01

    The multilayer coating for high gradients is reviewed. Not only the S-I-S structure, but also the S-S bilayer structure are also treated. This is an incomplete manuscript of an invited article which will be submitted to a journal. I have uploaded this version in order to help the understanding on my talk at the TESLA Technology Collaboration meeting at Saclay, France.

  3. Future of gradient index optics

    Science.gov (United States)

    Hashizume, Hideki; Hamanaka, Kenjiro; Graham, Alan C., III; Zhu, X. Frank

    2001-11-01

    First developed over 30 years ago, gradient index lenses play an important role not only in telecommunications technology, but also in applications such as information interface and biomedical technology. Traditional manufacturing consists of doping a certain ion, A+ into the mother glass, drawing the glass into rods and then immersing the rods into s molten salt bath containing another certain ion B+. During a thermal ion exchange process, the original ion migrates out of the mother glass, and is replaced by the alternate ion, creating a refractive index variation. Current research is being conducted to improve the thermal ion exchange technology, and open new applications. This research includes extending working distances to greater than 100mm, decreasing the lens diameter, increasing the effective radius, and combining the technology with other technologies such as photolithographically etched masks to produce arrays of gradient index lenses. As a result of this ongoing research, the gradient index lens is expected to continue to be the enabling optical technology in the first decade of the new millennium and beyond.

  4. Primordial vorticity and gradient expansion

    Science.gov (United States)

    Giovannini, Massimo; Rezaei, Zahra

    2012-02-01

    The evolution equations of the vorticities of the electrons, ions and photons in a pre-decoupling plasma are derived, in a fully inhomogeneous geometry, by combining the general relativistic gradient expansion and the drift approximation within the Adler-Misner-Deser decomposition. The vorticity transfer between the different species is discussed in this novel framework and a set of general conservation laws, connecting the vorticities of the three-component plasma with the magnetic field intensity, is derived. After demonstrating that a source of large-scale vorticity resides in the spatial gradients of the geometry and of the electromagnetic sources, the total vorticity is estimated to lowest order in the spatial gradients and by enforcing the validity of the momentum constraint. By acknowledging the current bounds on the tensor to scalar ratio in the (minimal) tensor extension of the ΛCDM paradigm, the maximal comoving magnetic field induced by the total vorticity turns out to be, at most, of the order of 10-37 G over the typical comoving scales ranging between 1 and 10 Mpc. While the obtained results seem to be irrelevant for seeding a reasonable galactic dynamo action, they demonstrate how the proposed fully inhomogeneous treatment can be used for the systematic scrutiny of pre-decoupling plasmas beyond the conventional perturbative expansions.

  5. Primordial vorticity and gradient expansion

    CERN Document Server

    Giovannini, Massimo

    2012-01-01

    The evolution equations of the vorticities of the electrons, ions and photons in a pre-decoupling plasma are derived, in a fully inhomogeneous geometry, by combining the general relativistic gradient expansion and the drift approximation within the Adler-Misner-Deser decomposition. The vorticity transfer between the different species is discussed in this novel framework and a set of general conservation laws, connecting the vorticities of the three-component plasma with the magnetic field intensity, is derived. After demonstrating that a source of large-scale vorticity resides in the spatial gradients of the geometry and of the electromagnetic sources, the total vorticity is estimated to lowest order in the spatial gradients and by enforcing the validity of the momentum constraint. By acknowledging the current bounds on the tensor to scalar ratio in the (minimal) tensor extension of the $\\Lambda$CDM paradigm the maximal comoving magnetic field induced by the total vorticity turns out to be, at most, of the or...

  6. Rapid Scan Humidified Growth Cloud Condensation Nuclei Counter

    Energy Technology Data Exchange (ETDEWEB)

    Gregory L. Kok; Athanasios Nenes

    2013-03-13

    This research focused on enhancements to the streamwise thermal gradient cloud condensation nuclei counter to support the rapid scan mode and to enhance the capability for aerosol humidified growth measurements. The research identified the needs for flow system modifications and range of capability for operating the conventional instrument in the rapid scan and humidified growth modes.

  7. On the structure of gradient Yamabe solitons

    CERN Document Server

    Cao, Huai-Dong; Zhang, Yingying

    2011-01-01

    We show that every complete nontrivial gradient Yamabe soliton admits a special global warped product structure with a one-dimensional base. Based on this, we prove a general classification theorem for complete nontrivial locally conformally flat gradient Yamabe solitons.

  8. Community and ecosystem responses to elevational gradients

    DEFF Research Database (Denmark)

    Sundqvist, Maja K.; Sanders, Nate; Wardle, David A.

    2013-01-01

    Community structure and ecosystem processes often vary along elevational gradients. Their responses to elevation are commonly driven by changes in temperature, and many community- and ecosystem-level variables therefore frequently respond similarly to elevation across contrasting gradients. There...

  9. Gradient Flow Convolutive Blind Source Separation

    DEFF Research Database (Denmark)

    Pedersen, Michael Syskind; Nielsen, Chinton Møller

    2004-01-01

    Experiments have shown that the performance of instantaneous gradient flow beamforming by Cauwenberghs et al. is reduced significantly in reverberant conditions. By expanding the gradient flow principle to convolutive mixtures, separation in a reverberant environment is possible. By use of a circ......Experiments have shown that the performance of instantaneous gradient flow beamforming by Cauwenberghs et al. is reduced significantly in reverberant conditions. By expanding the gradient flow principle to convolutive mixtures, separation in a reverberant environment is possible. By use...

  10. Microecology: Using Fast-Growing Filamentous Fungi to Study the Effects of Environmental Gradients on the Growth Patterns of Hyphae

    Science.gov (United States)

    Delpech, Roger

    2004-01-01

    This paper describes some simple and rapid techniques for examining the growth responses of fungal hyphae cultivated on environmental gradients. The creation of such gradients using agar-based growth media in petri dishes is explained, along with recommendations for quantitative macroscopic and microscopic measurements. The intention is to provide…

  11. An education gradient in health, a health gradient in education, or a confounded gradient in both?

    Science.gov (United States)

    Lynch, Jamie L; von Hippel, Paul T

    2016-04-01

    There is a positive gradient associating educational attainment with health, yet the explanation for this gradient is not clear. Does higher education improve health (causation)? Do the healthy become highly educated (selection)? Or do good health and high educational attainment both result from advantages established early in the life course (confounding)? This study evaluates these competing explanations by tracking changes in educational attainment and Self-rated Health (SRH) from age 15 to age 31 in the National Longitudinal Study of Youth, 1997 cohort. Ordinal logistic regression confirms that high-SRH adolescents are more likely to become highly educated. This is partly because adolescent SRH is associated with early advantages including adolescents' academic performance, college plans, and family background (confounding); however, net of these confounders adolescent SRH still predicts adult educational attainment (selection). Fixed-effects longitudinal regression shows that educational attainment has little causal effect on SRH at age 31. Completion of a high school diploma or associate's degree has no effect on SRH, while completion of a bachelor's or graduate degree have effects that, though significant, are quite small (less than 0.1 points on a 5-point scale). While it is possible that educational attainment would have greater effect on health at older ages, at age 31 what we see is a health gradient in education, shaped primarily by selection and confounding rather than by a causal effect of education on health.

  12. Nonlinear cross Gramians and gradient systems

    NARCIS (Netherlands)

    Ionescu, T. C.; Scherpen, J. M. A.

    2007-01-01

    We study the notion of cross Gramians for nonlinear gradient systems, using the characterization in terms of prolongation and gradient extension associated to the system. The cross Gramian is given for the variational system associated to the original nonlinear gradient system. We obtain

  13. 40 CFR 230.25 - Salinity gradients.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Salinity gradients. 230.25 Section 230... Physical and Chemical Characteristics of the Aquatic Ecosystem § 230.25 Salinity gradients. (a) Salinity... fresh or salt water may change existing salinity gradients. For example, partial blocking of...

  14. Rapid Identification of Bacteria Directly from Positive Blood Cultures by Use of a Serum Separator Tube, Smudge Plate Preparation, and Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry.

    Science.gov (United States)

    Chen, Yan; Porter, Vanessa; Mubareka, Samira; Kotowich, Leona; Simor, Andrew E

    2015-10-01

    We analyzed the matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) of smudge plate growth for bacterial identification from 400 blood cultures. Ninety-seven percent of Gram-negative bacilli and 85% of Gram-positive organisms were correctly identified within 4 h; only eight isolates (2.0%) were misidentified. This method provided rapid and accurate microbial identification from positive blood cultures.

  15. Stringy bounces and gradient instabilities

    CERN Document Server

    Giovannini, Massimo

    2017-01-01

    Bouncing solutions are obtained from a generally covariant action characterized by a potential which is a nonlocal functional of the dilaton field at two separated space-time points. Gradient instabilities are shown to arise in this context but they are argued to be nongeneric. After performing a gauge-invariant and frame-invariant derivation of the evolution equations of the fluctuations, a heuristic criterium for the avoidance of pathological instabilities is proposed and corroborated by a number of explicit examples that turn out to be compatible with a quasi-flat spectrum of curvature inhomogeneities for typical wavelengths larger than the Hubble radius.

  16. Temperature Gradient in Hall Thrusters

    Energy Technology Data Exchange (ETDEWEB)

    D. Staack; Y. Raitses; N.J. Fisch

    2003-11-24

    Plasma potentials and electron temperatures were deduced from emissive and cold floating probe measurements in a 2 kW Hall thruster, operated in the discharge voltage range of 200-400 V. An almost linear dependence of the electron temperature on the plasma potential was observed in the acceleration region of the thruster both inside and outside the thruster. This result calls into question whether secondary electron emission from the ceramic channel walls plays a significant role in electron energy balance. The proportionality factor between the axial electron temperature gradient and the electric field is significantly smaller than might be expected by models employing Ohmic heating of electrons.

  17. Learning from nature: synthesis and characterization of longitudinal polymer gradient materials inspired by mussel byssus threads.

    Science.gov (United States)

    Claussen, Kai U; Giesa, Reiner; Scheibel, Thomas; Schmidt, Hans-Werner

    2012-02-13

    Marine mussels use their threads for attachment to any substratum and these biopolymer gradient fibers show an excellent combination of stiff and soft mechanical properties. A straightforward approach for the preparation of macroscopic longitudinal polymer gradient materials on the centimeter scale based on a poly(dimethyl siloxane) system is presented. Compositional gradients are realized by using three syringe pumps feeding different prepolymers capable to undergo thermal cross-linking. Within the gradient samples, the stiffness between the hard and soft part can be varied up to a factor of four. The gradients are analyzed by UV-Vis spectroscopy as well as compressive and tensile modulus testing. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Engineering functionality gradients by dip coating process in acceleration mode.

    Science.gov (United States)

    Faustini, Marco; Ceratti, Davide R; Louis, Benjamin; Boudot, Mickael; Albouy, Pierre-Antoine; Boissière, Cédric; Grosso, David

    2014-10-08

    In this work, unique functional devices exhibiting controlled gradients of properties are fabricated by dip-coating process in acceleration mode. Through this new approach, thin films with "on-demand" thickness graded profiles at the submillimeter scale are prepared in an easy and versatile way, compatible for large-scale production. The technique is adapted to several relevant materials, including sol-gel dense and mesoporous metal oxides, block copolymers, metal-organic framework colloids, and commercial photoresists. In the first part of the Article, an investigation on the effect of the dip coating speed variation on the thickness profiles is reported together with the critical roles played by the evaporation rate and by the viscosity on the fluid draining-induced film formation. In the second part, dip-coating in acceleration mode is used to induce controlled variation of functionalities by playing on structural, chemical, or dimensional variations in nano- and microsystems. In order to demonstrate the full potentiality and versatility of the technique, original graded functional devices are made including optical interferometry mirrors with bidirectional gradients, one-dimensional photonic crystals with a stop-band gradient, graded microfluidic channels, and wetting gradient to induce droplet motion.

  19. Fabrication of Janus hydrogels with stiffness gradient using drop coalescence

    Science.gov (United States)

    Lee, Donghee; Golden, Kale; Ryu, Sangjin

    2016-11-01

    The stiffness of the extracellular matrix (ECM) regulates cellular behaviors, and polyacrylamide (PAAM) gels with stiffness gradient have been used to simulate inhomogeneous ECM and to study the effects of the ECM stiffness on cells. Such hydrogel substrates with stiffness gradient can be fabricated with relatively complicated methods using microfluidics and moving masks. In our study, we develop a simpler method for fabricating Janus hydrogel which has a gradient of stiffness. Two prepolymer solutions were prepared for soft and stiff gel compositions, respectively, and one drop of each solution was placed on a hydrophobic patterned glass. Then, these two drops were gently squeezed by another glass being slowly lowered until coalescence, and gel polymerization was initiated after a certain time period for mixing. The motion of the drops was guided by the hydrophobic pattern. AFM nano-indentation showed that the fabricated Janus PAAM gels have a stiffness gradient which could be controlled by increasing mixing time. This study was supported by Bioengineering for Human Health Grant from UNL and UNMC.

  20. Mechanisms of FGF gradient formation during embryogenesis.

    Science.gov (United States)

    Balasubramanian, Revathi; Zhang, Xin

    2016-05-01

    Fibroblast growth factors (FGFs) have long been attributed to influence morphogenesis in embryonic development. Signaling by FGF morphogen encodes positional identity of tissues by creating a concentration gradient over the developing embryo. Various mechanisms that influence the development of such gradient have been elucidated in the recent past. These mechanisms of FGF gradient formation present either as an extracellular control over FGF ligand diffusion or as a subcellular control of FGF propagation and signaling. In this review, we describe our current understanding of FGF as a morphogen, the extracellular control of FGF gradient formation by heparan sulfate proteoglycans (HSPGs) and mechanisms of intracellular regulation of FGF signaling that influence gradient formation.

  1. Fluvial signatures of modern and paleo orographic rainfall gradients

    Science.gov (United States)

    Schildgen, Taylor; Strecker, Manfred

    2016-04-01

    arid precipitation regimes. Indeed, despite uniform lithology and uplift history, we see patterns in river steepness values and in chi plots that are consistest a rainfall gradient on the (former) windward side of the range and asymmetric precipitation across the range. We suggest that morphological aspects of the river networks in such regions are dominated by their history of changing climate. These morphologic signatures appear to persist for millions of years in NW Argentina, most likely because the transition from a wetter to a drier climate has prevented a rapid readjustment to new forcing conditions. Reference: Han, J., Gasparini, N.M., and Johnson, J.P., 2015, Measuring the imprint of orographic rainfall gradients on the morphology of steady-state numerical fluvial landscapes. Earth Surf. Process. Landforms, 40(10), 1334-1350.

  2. NIF optics phase gradient specfication

    Energy Technology Data Exchange (ETDEWEB)

    Williams, W.; Auerbach, J.; Hunt, J.; Lawson, L.; Manes, K.; Orth, C.; Sacks, R.; Trenholme, J.; Wegner, P.

    1997-05-02

    A root-mean-square (rms) phase gradient specification seems to allow a good connection between the NIP optics quality and focal spot requirements. Measurements on Beamlet optics individually, and as a chain, indicate they meet the assumptions necessary to use this specification, and that they have a typical rms phase gradient of {approximately}80 {angstrom}/cm. This may be sufficient for NIP to meet the proposed Stockpile Stewardship Management Program (SSMP) requirements of 80% of a high- power beam within a 200-250 micron diameter spot. Uncertainties include, especially, the scale length of the optics phase noise, the ability of the adaptive optic to correct against pump-induced distortions and optics noise, and the possibility of finding mitigation techniques against whole-beam self-focusing (e.g. a pre- correction optic). Further work is needed in these areas to better determine the NIF specifications. This memo is a written summary of a presentation on this topic given by W. Williams 24 April 1997 to NIP and LS&T personnel.

  3. Theory of the Alternating-Gradient Synchrotron

    Science.gov (United States)

    Courant, E. D.; Snyder, H. S.

    2000-04-01

    The equations of motion of the particles in a synchrotron in which the field gradient indexn=-(r/B) ∂B/∂rvaries along the equilibrium orbit are examined on the basis of the linear approximation. It is shown that if n alternates rapidly between large positive and large negative values, the stability of both radial and vertical oscillations can be greatly increased compared to conventional accelerators in which n is azimuthally constant and must lie between 0 and 1. Thus aperture requirements are reduced. For practical designs, the improvement is limited by the effects of constructional errors; these lead to resonance excitation of oscillations and consequent instability if 2νx or 2νz or νx+νz is integral, where νx and νz are the frequencies of horizontal and vertical betatron oscillations, measured in units of the frequency of revolution. The mechanism of phase stability is essentially the same as in a conventional synchrotron, but the radial amplitude of synchrotron oscillations is reduced substantially. Furthermore, at a "transition energy" E1≈νxMc2 the stable and unstable equilibrium phases exchange roles, necessitating a jump in the phase of the radiofrequency accelerating voltage. Calculations indicate that the manner in which this jump is performed is not very critical.

  4. Surface composition gradients of immobilized cell signaling molecules. Epidermal growth factor on gold

    Energy Technology Data Exchange (ETDEWEB)

    Wang Qian [Department of Chemistry and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, IL 61801 (United States); Bohn, Paul W. [Department of Chemistry and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, IL 61801 (United States)]. E-mail: bohn@scs.uiuc.edu

    2006-08-14

    Surface composition gradients of the signaling molecule, epidermal growth factor (EGF), have been prepared by an adaptation of the electrochemical gradient technique. EGF is covalently bound to the reactive component, 11-amino-l-undecanethiol (AUT), in a counterpropagating two-component gradient composed of AUT and poly(ethylene glycol) thiol (PEG) using carbodiimide coupling chemistry. Areas of the surface presenting -NH{sub 2} termination react with succinimidyl esters of solvent-accessible acidic amino acids in EGF, while non-specific protein adsorption is resisted in the PEG regions. The maximum surface coverage of EGF prepared in this manner was determined by surface plasmon resonance reflectometry (SPR) on spatially uniform films to be 20% < {gamma} {sub EGF} < 70% depending on the concentration of the EGF derivatization solution. EGF retains its biological activity with this immobilization process, as verified by culturing human umbilical vein endothelial cell (HUVEC) on an EGF-terminated surface for 24 h. PEG shows good resistance to EGF physical adsorption as demonstrated by both SPR and X-ray photoelectron spectroscopy (XPS). The N / C ratio of EGF gradients, which is characteristic of EGF adsorption, because only the protein contains N, while both protein and PEG contain C, was spatially mapped with XPS. The gradient composition distributions are sigmoidal with lateral distance, with the position of the gradient transition region being readily controlled by adjusting the applied potential window. EGF gradients with variable quantitative surface coverage profiles were generated by varying EGF and AUT concentrations.

  5. Radiation emitted by transverse-gradient undulators

    Directory of Open Access Journals (Sweden)

    Axel Bernhard

    2016-09-01

    Full Text Available Conventional undulators are used in synchrotron light sources to produce radiation with a narrow relative spectral width as compared to bending magnets or wigglers. The spectral width of the radiation produced by conventional undulators is determined by the number of undulator periods and by the energy spread and emittance of the electron beam. In more compact electron sources like for instance laser plasma accelerators the energy spread becomes the dominating factor. Due to this effect these electron sources cannot in general be used for high-gain free electron lasers (FELs. In order to overcome this limitation, modified undulator schemes, so-called transverse gradient undulators (TGUs, were proposed and a first superconducting TGU was built at Karlsruhe Institute of Technology (KIT, Karlsruhe, Germany. In this paper simulations of the expected synchrotron radiation spectral distribution are presented. An experimental test with that device is under preparation at the laser wakefield accelerator at the JETI laser at the University of Jena, Germany.

  6. Manipulating particles with light: radiation and gradient forces

    Science.gov (United States)

    Bradshaw, David S.; Andrews, David L.

    2017-05-01

    The manipulation of matter with electromagnetic radiation is a capacity that has been known for over a century. However, the prominence of such optical effects only grew rapidly following the invention of optical tweezers in the 1980s. While both the original theory and the early trapping techniques are based on the radiation force, optical tweezing uses the gradient force. This paper aims to differentiate between these two clearly distinct types of optical forces, which are sometimes confused in the literature. We also discuss three completely separate forms of optical torque that can be applied to a particle, also due to an electromagnetic field. These involve the transfer of either spin or orbital angular momentum from the beam to the particle, depending on the character of the light, or the often overlooked alignment effect that can act on a cylindrical particle due to a gradient force.

  7. Nonchaotic stagnant motion in a marginal quasiperiodic gradient system.

    Science.gov (United States)

    Mitsui, Takahito

    2008-08-01

    A one-dimensional dynamical system with a marginal quasiperiodic gradient is presented as a mathematical extension of a nonuniform oscillator. The system exhibits a nonchaotic stagnant motion, which is reminiscent of intermittent chaos. In fact, the density function of residence times near stagnation points obeys an inverse-square law, due to a mechanism similar to type-I intermittency. However, unlike intermittent chaos, in which the alternation between long stagnant phases and rapid moving phases occurs in a random manner, here the alternation occurs in a quasiperiodic manner. In particular, in the case of a gradient with the golden ratio, the renewal of the largest residence time occurs at positions corresponding to the Fibonacci sequence. Finally, the asymptotic long-time behavior, in the form of a nested logarithm, is theoretically derived. Compared with the Pomeau-Manneville intermittency, a significant difference in the relaxation property of the long-time average of the dynamical variable is found.

  8. Fitting magnetic field gradient with Heisenberg-scaling accuracy.

    Science.gov (United States)

    Zhang, Yong-Liang; Wang, Huan; Jing, Li; Mu, Liang-Zhu; Fan, Heng

    2014-12-09

    The linear function is possibly the simplest and the most used relation appearing in various areas of our world. A linear relation can be generally determined by the least square linear fitting (LSLF) method using several measured quantities depending on variables. This happens for such as detecting the gradient of a magnetic field. Here, we propose a quantum fitting scheme to estimate the magnetic field gradient with N-atom spins preparing in W state. Our scheme combines the quantum multi-parameter estimation and the least square linear fitting method to achieve the quantum Cramér-Rao bound (QCRB). We show that the estimated quantity achieves the Heisenberg-scaling accuracy. Our scheme of quantum metrology combined with data fitting provides a new method in fast high precision measurements.

  9. Dependence of bacterial chemotaxis on gradient shape and adaptation rate.

    Directory of Open Access Journals (Sweden)

    Nikita Vladimirov

    2008-12-01

    Full Text Available Simulation of cellular behavior on multiple scales requires models that are sufficiently detailed to capture central intracellular processes but at the same time enable the simulation of entire cell populations in a computationally cheap way. In this paper we present RapidCell, a hybrid model of chemotactic Escherichia coli that combines the Monod-Wyman-Changeux signal processing by mixed chemoreceptor clusters, the adaptation dynamics described by ordinary differential equations, and a detailed model of cell tumbling. Our model dramatically reduces computational costs and allows the highly efficient simulation of E. coli chemotaxis. We use the model to investigate chemotaxis in different gradients, and suggest a new, constant-activity type of gradient to systematically study chemotactic behavior of virtual bacteria. Using the unique properties of this gradient, we show that optimal chemotaxis is observed in a narrow range of CheA kinase activity, where concentration of the response regulator CheY-P falls into the operating range of flagellar motors. Our simulations also confirm that the CheB phosphorylation feedback improves chemotactic efficiency by shifting the average CheY-P concentration to fit the motor operating range. Our results suggest that in liquid media the variability in adaptation times among cells may be evolutionary favorable to ensure coexistence of subpopulations that will be optimally tactic in different gradients. However, in a porous medium (agar such variability appears to be less important, because agar structure poses mainly negative selection against subpopulations with low levels of adaptation enzymes. RapidCell is available from the authors upon request.

  10. A STUDY OF RAPID CAVITY TUNING.

    Energy Technology Data Exchange (ETDEWEB)

    ZHAO, Y.

    2001-07-12

    An FFAG moot likely requires rapid cavity tuning. The cavity must also have a very high gradient. To satisfy both the high power and rapid tuning requirements is a big challenge. Detailed investigation of the possibility is addressed. Included are general thoughts, dual-loop and simple loop analyses, and a study of using ferrite or PIN diodes. Also proposed is a phase control scheme, which may be a better solution if the needed components can be developed. Finally, an energy analysis reveals the difficult of high power tuning.

  11. Rapid shallow breathing

    Science.gov (United States)

    Tachypnea; Breathing - rapid and shallow; Fast shallow breathing; Respiratory rate - rapid and shallow ... Shallow, rapid breathing has many possible medical causes, including: Asthma Blood clot in an artery in the lung Choking Chronic obstructive ...

  12. Wnt Secretion and Gradient Formation

    Directory of Open Access Journals (Sweden)

    Vladimir L. Katanaev

    2013-03-01

    Full Text Available Concentration gradients formed by the lipid-modified morphogens of the Wnt family are known for their pivotal roles during embryogenesis and adult tissue homeostasis. Wnt morphogens are also implicated in a variety of human diseases, especially cancer. Therefore, the signaling cascades triggered by Wnts have received considerable attention during recent decades. However, how Wnts are secreted and how concentration gradients are formed remains poorly understood. The use of model organisms such as Drosophila melanogaster has provided important advances in this area. For instance, we have previously shown that the lipid raft-associated reggie/flotillin proteins influence Wnt secretion and spreading in Drosophila. Our work supports the notion that producing cells secrete Wnt molecules in at least two pools: a poorly diffusible one and a reggie/flotillin-dependent highly diffusible pool which allows morphogen spreading over long distances away from its source of production. Here we revise the current views of Wnt secretion and spreading, and propose two models for the role of the reggie/flotillin proteins in these processes: (i reggies/flotillins regulate the basolateral endocytosis of the poorly diffusible, membrane-bound Wnt pool, which is then sorted and secreted to apical compartments for long-range diffusion, and (ii lipid rafts organized by reggies/flotillins serve as “dating points” where extracellular Wnt transiently interacts with lipoprotein receptors to allow its capture and further spreading via lipoprotein particles. We further discuss these processes in the context of human breast cancer. A better understanding of these phenomena may be relevant for identification of novel drug targets and therapeutic strategies.

  13. 番茄叶片基因组DNA快速制备技术及其在基于实时荧光定量PCR的转基因检测中的应用%Techniques for rapid preparation of tomato leaf DNA and its application in real-time quantitative PCR-based transgene detection

    Institute of Scientific and Technical Information of China (English)

    王伟伟; 朱长青; 刘小花; 陈昆松; 徐昌杰

    2011-01-01

    Using tomato (Solanum lycopersicum L. Cv. Micro-Tom) leaf as material, a simple and rapid DNA preparation protocol was established. This method required only 2-20 mm2 leaf with only one extraction solution and involved one pipetation and one centrifugation each. No precipitation was required. The suitable volume of prepared DNA solution, as PCR template, for real-time quantitative PCR was determined to be 0.1-0.2 μL in 12.5 μL final reaction volume. The excessive template DNA solution was confirmed to reduce PCR efficiency and even can result in PCR failure. This technique for rapid preparation of DNA and a compatible real-time quantitative PCR were successfully applied in transgene detection of tomato plants.%以番茄(Solanum lycopersicumL.cv.Micro-Tom)叶片为试材,建立了一种简便快速制备叶片基因组DNA的方法.2~20 mm2的叶片即可满足制备要求,制备过程只需一种提取试剂、只涉及1次移液和1次离心操作,不涉及沉淀.确定了所制备的DNA用于实时荧光定量PCR的合适用量为0.1~0.2 μL(反应总体积为12.5 μL),发现过量模板的使用可降低PCR效率且可导致扩增失败.该项DNA快速制备及相适应的实时荧光定量PCR技术已成功应用于番茄转基因植株检测.

  14. Biomimetic Gradient Polymers with Enhanced Damping Capacities.

    Science.gov (United States)

    Wang, Dong; Zhang, Huan; Guo, Jing; Cheng, Beichen; Cao, Yuan; Lu, Shengjun; Zhao, Ning; Xu, Jian

    2016-04-01

    Designing gradient structures, mimicking biological materials, such as pummelo peels and tendon, is a promising strategy for developing advanced materials with superior energy damping capacities. Here a facile and effective approach for fabricating polymers with composition gradients at millimeter length scale is presented. The gradient thiol-ene polymers (TEPs) are created by the use of density difference of ternary thiol-ene-ene precursors and the subsequent photo-crosslinking via thiol-ene reaction. The compositional gradients are analyzed via differential scanning calorimeter (DSC), compressive modulus testing, atomic force microscopy (AFM) indentation, and swelling measurements. In contrast to homogeneous TEPs networks, the resultant gradient polymer shows a broader effective damping temperature range combining with good mechanical properties. The present result provides an effective route toward high damping materials by the fabrication of gradient structures.

  15. Strain gradient effects on cyclic plasticity

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Legarth, Brian Nyvang

    2010-01-01

    hardening materials it is quantified how dissipative and energetic gradient effects promote hardening above that of conventional predictions. Usually, increased hardening is attributed to energetic gradient effects, but here it is found that also dissipative gradient effects lead to additional hardening...... in the presence of conventional material hardening. Furthermore, it is shown that dissipative gradient effects can lead to both an increase and a decrease in the dissipation per load cycle depending on the magnitude of the dissipative length parameter, whereas energetic gradient effects lead to decreasing...... dissipation for increasing energetic length parameter. For dissipative gradient effects it is found that dissipation has a maximum value for some none zero value of the material length parameter, which depends on the magnitude of the deformation cycles....

  16. Mathematics of Experimentally Generated Chemoattractant Gradients.

    Science.gov (United States)

    Postma, Marten; van Haastert, Peter J M

    2016-01-01

    Many eukaryotic cells move in the direction of a chemical gradient. Several assays have been developed to measure this chemotactic response, but no complete mathematical models of the spatial and temporal gradients are available to describe the fundamental principles of chemotaxis. Here we provide analytical solutions for the gradients formed by release of chemoattractant from a point source by passive diffusion or forced flow (micropipettes) and gradients formed by laminar diffusion in a Zigmond chamber. The results show that gradients delivered with a micropipette are formed nearly instantaneously, are very steep close to the pipette, and have a steepness that is strongly dependent on the distance from the pipette. In contrast, gradients in a Zigmond chamber are formed more slowly, are nearly independent of the distance from the source, and resemble the temporal and spatial properties of the natural cAMP wave that Dictyostelium cells experience during cell aggregation.

  17. Dynamic nucleotide mutation gradients and control region usage in squamate reptile mitochondrial genomes.

    Science.gov (United States)

    Castoe, T A; Gu, W; de Koning, A P J; Daza, J M; Jiang, Z J; Parkinson, C L; Pollock, D D

    2009-01-01

    Gradients of nucleotide bias and substitution rates occur in vertebrate mitochondrial genomes due to the asymmetric nature of the replication process. The evolution of these gradients has previously been studied in detail in primates, but not in other vertebrate groups. From the primate study, the strengths of these gradients are known to evolve in ways that can substantially alter the substitution process, but it is unclear how rapidly they evolve over evolutionary time or how different they may be in different lineages or groups of vertebrates. Given the importance of mitochondrial genomes in phylogenetics and molecular evolutionary research, a better understanding of how asymmetric mitochondrial substitution gradients evolve would contribute key insights into how this gradient evolution may mislead evolutionary inferences, and how it may also be incorporated into new evolutionary models. Most snake mitochondrial genomes have an additional interesting feature, 2 nearly identical control regions, which vary among different species in the extent that they are used as origins of replication. Given the expanded sampling of complete snake genomes currently available, together with 2 additional snakes sequenced in this study, we reexamined gradient strength and CR usage in alethinophidian snakes as well as several lizards that possess dual CRs. Our results suggest that nucleotide substitution gradients (and corresponding nucleotide bias) and CR usage is highly labile over the approximately 200 m.y. of squamate evolution, and demonstrates greater overall variability than previously shown in primates. The evidence for the existence of such gradients, and their ability to evolve rapidly and converge among unrelated species suggests that gradient dynamics could easily mislead phylogenetic and molecular evolutionary inferences, and argues strongly that these dynamics should be incorporated into phylogenetic models.

  18. DNA purification from crude samples for human identification using gradient elution isotachophoresis.

    Science.gov (United States)

    Strychalski, Elizabeth A; Konek, Christopher; Butts, Erica L R; Vallone, Peter M; Henry, Alyssa C; Ross, David

    2013-09-01

    Gradient elution isotachophoresis (GEITP) was demonstrated for DNA purification, concentration, and quantification from crude samples, represented here by soiled buccal swabs, with minimal sample preparation prior to human identification using STR analysis. During GEITP, an electric field applied across leading and trailing electrolyte solutions resulted in isotachophoretic focusing of DNA at the interface between these solutions, while a pressure-driven counterflow controlled the movement of the interface from the sample reservoir into a microfluidic capillary. This counterflow also prevented particulates from fouling or clogging the capillary and reduced or eliminated contamination of the delivered DNA by PCR inhibitors. On-line DNA quantification using laser-induced fluorescence compared favorably with quantitative PCR measurements and potentially eliminates the need for quantitative PCR prior to STR analysis. GEITP promises to address the need for a rapid and robust method to deliver DNA from crude samples to aid the forensic community in human identification. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Nonlinear cross Gramians and gradient systems

    OpenAIRE

    Ionescu, T. C.; Scherpen, J.M.A.

    2007-01-01

    We study the notion of cross Gramians for nonlinear gradient systems, using the characterization in terms of prolongation and gradient extension associated to the system. The cross Gramian is given for the variational system associated to the original nonlinear gradient system. We obtain linearization results that precisely correspond to the notion of a cross Gramian for symmetric linear systems. Furthermore, first steps towards relations with the singular value functions of the nonlinear Han...

  20. Wireless SAW Based Temperature Gradient Sensor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Prime Photonics proposes design and development of a surface acoustic wave (SAW) based temperature gradient sensor for instrumentation of thermal protection systems...

  1. On lower order strain gradient plasticity theories

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Hutchinson, J. W.

    2003-01-01

    the tangent moduli governing increments of stress and strain. It is shown that the modification is far from benign from a mathematical standpoint, changing the qualitative character of solutions and leading to a new type of localization that is at odds with what is expected from a strain gradient theory......By way of numerical examples, this paper explores the nature of solutions to a class of strain gradient plasticity theories that employ conventional stresses, equilibrium equations and boundary conditions. Strain gradients come into play in these modified conventional theories only to alter....... The findings raise questions about the physical acceptability of this class of strain gradient theories....

  2. INFLUENCES OF SLOPE GRADIENT ON SOIL EROSION

    Institute of Scientific and Technical Information of China (English)

    刘青泉; 陈力; 李家春

    2001-01-01

    The main factors influencing soil erosion include the net rain excess, the water depth, the velocity, the shear stress of overland flows , and the erosion-resisting capacity of soil. The laws of these factors varying with the slope gradient were investigated by using the kinematic wave theory. Furthermore, the critical slope gradient of erosion was driven. The analysis shows that the critical slope gradient of soil erosion is dependent on grain size , soil bulk density , surface roughness, runoff length, net rain excess, and the friction coefficient of soil, etc. The critical slope gradient has been estimated theoretically with its range between 41. 5 °~ 50°.

  3. 双缩脲法检测奶粉中总蛋白质快速检测试纸的研制%Preparation of rapid detecting paper for total protein in milk powder by biuret method

    Institute of Scientific and Technical Information of China (English)

    马丽华; 田雨; 姜瞻梅; 田波

    2012-01-01

    研制了能够快速测定奶粉中总蛋白质含量的双缩脲检测试纸。将试纸于1.5倍标准双缩脲试剂浓度的溶液中浸泡10min,60℃干燥15min,滴加样品反应10min,放入光电检测仪,在波长560nm下检测。结果表明,本法线性范围为0~20.0mg/mL,检出限为0.85mg/mL,加标回收率为96.84%~99.23%,测定相对误差为1.01%~1.91%。用本法和凯氏定氮法同时对奶粉样品进行检测,经检验二者测定结果之间差异无统计学意义。该法操作简单、检测迅速、准确度和灵敏度高,适合奶粉中总蛋白质的现场快速检测。%A kind of testing paper which can rapidly detect the content of protein in milk powder was developed. Putting the test paper in the lipid of 1.5 times standard biuret soaks for 10min and dry for 15min in 60℃ conditions,then dropping the sample make the reaction last 10min,detected the test paper at 560nm wavelength by photoelectric detector, The results showed that this method's linear range was 0-20.0mg/mL. The detection limit reached 0.85mg/mL. The recovery of standard addition was 96.84%-99.23% and relative error was 1.01%-1.91%. Comparing the method and Kjeldahl in detecting of milk powder found that there was no statistic difference between the results. So this method can be applied to the quick determination of protein in milk powder with the advantages of simple operation, rapid detection, high accuracy and precision,

  4. Dynamic in-plane potential gradients for actively controlling electrochemical reactions: Part I. Characterization of 1- and 2-component alkanethiol monolayer gradients on thin gold films. Part II. Applications of in-plane potential gradients

    Science.gov (United States)

    Balss, Karin Maria

    The research contained in this thesis is focused on the formation and characterization of surface composition gradients on thin gold films that are formed by applications of in-plane potential gradients. Injecting milliamp currents into thin Au films yields significant in-plane voltage drops so that, rather than assuming a single value of potential, an in-plane potential gradient is imposed on the film which depends on the resistivity of the film, the cross sectional area and the magnitude of the potential drop. Furthermore, the in-plane electric potential gradient means that, relative to a solution reference couple, electrochemical reactions occurs at defined spatial positions corresponding to the local potential, V(x) ˜ E0. The spatial gradient in electrochemical potential can then produce spatially dependent electrochemistry. Surface-chemical potential gradients can be prepared by arranging the spread of potentials to span an electrochemical wave mediating redox-associated adsorption or desorption. Examples of reactions that can be spatially patterned include the electrosorption of alkanethiols and over-potential metal deposition. The unique advantage of this method for patterning spatial compositions is the control of surface coverage in both space and time. The thesis is organized into two parts. In Part I, formation and characterization of 1- and 2-component alkanethiol monolayer gradients is investigated. Numerous surface science tools are employed to examine the distribution in coverage obtained by application of in-plane potential gradients. Macroscopic characterization was obtained by sessile water drop contact angle measurements and surface plasmon resonance imaging. Gradients were also imaged on micron length scales with pulsed-force mode atomic force microscopy. Direct chemical evidence of surface compositions in aromatic thiol surface coverage was obtained by surface-enhanced Raman spectroscopy. In Part II, the applications of in-plane potential

  5. Rapid quantification of piroxicam in piroxicam preparations by using LC-MS/MS%LC-MS/MS法快速测定吡罗昔康制剂中吡罗昔康含量

    Institute of Scientific and Technical Information of China (English)

    张军民; 傅思武; 赵晋; 郭裕临; 石晓峰

    2012-01-01

    An improved method was developed for the quantification of piroxicam in piroxicam preparation by ultra fast liquid chromatography/tandem mass spectrometry ( LC/MS/MS) . METHOD Sample preparation consisted of extraction by adding 0.1 mol/L hydrochloric acid in methanol, filtration with microporous membrane and centrifugation of the sample subsequently. LC/MS/MS detection was performed by using a triple-stage quadrupole mass spectrometer working in multiple reaction monitoring mode ( MRM) with positive eleclrospray ionization(ESI) , using the transitions of m/z 332. 2→94. 8 of piroxicam. Chromatographic separation was achieved using a 3. 0mm x 75mm, 2. 0 μm Shim-pack XR-ODS column with isocratic flow and elution with acetonitrile-water-formic acid (60;40:0.1, V/V/V) and a flow-rate of 0.4 mL/min. The analyte was quantified in a single run within 3 min. RESULTS Linearity was demonstrated over the expected concentration range of 2.5 ~ 1000. 0 ng/mL. The lower limit of quantification (LLOQ) was 2.5 ng/μmL. Intra-day precision expressed as RSD was less than 3.2%, while inter-day result was less than 3.8% for piroxicam. CONCLUSION The method has good repeatability, high sensitivity and more convenient, and can be successfully applied to the determination of piroxicam in piroxicam preparations. The described method is also suitable to for analysies of serum samples with very small volumes and for pharmacokinetic studies.%建立了快速液相色谱-质谱/质谱联用法测定吡罗昔康制剂中吡罗昔康含量的方法.样品以0.1 moL/L盐酸甲醇溶液提取、微孔滤膜过滤、离心后,通过电喷雾离子化(ESI),采用多反应检测(MRM)方式进行正离子检测,用于定量分析的检测离子为m/z 332.2→94.8.采用Shim-pack XR-ODS (3.0 mm×75mm,2.0μm)柱分离,以乙腈-水-甲酸(60:40:0.1,V/V/V)为流动相,流速为0.40 mL/min,在3 min内完成吡罗昔康定量分析.线性范围为2.5~1000.0ng/mL,最低检测限为2.5 ng/mL;日内测

  6. Rapid Polymer Sequencer

    Science.gov (United States)

    Stolc, Viktor (Inventor); Brock, Matthew W (Inventor)

    2013-01-01

    Method and system for rapid and accurate determination of each of a sequence of unknown polymer components, such as nucleic acid components. A self-assembling monolayer of a selected substance is optionally provided on an interior surface of a pipette tip, and the interior surface is immersed in a selected liquid. A selected electrical field is impressed in a longitudinal direction, or in a transverse direction, in the tip region, a polymer sequence is passed through the tip region, and a change in an electrical current signal is measured as each polymer component passes through the tip region. Each of the measured changes in electrical current signals is compared with a database of reference electrical change signals, with each reference signal corresponding to an identified polymer component, to identify the unknown polymer component with a reference polymer component. The nanopore preferably has a pore inner diameter of no more than about 40 nm and is prepared by heating and pulling a very small section of a glass tubing.

  7. Rapid Separation of Lactobacillus and Streptococcus in Yogurt and Preparation of Fermentation Agent%酸奶中杆菌和球菌的快速分离及发酵剂的制备

    Institute of Scientific and Technical Information of China (English)

    付鸿; 李靖靖; 岳春

    2013-01-01

    Because of symbiosis relation between Lactobacillus bulgaricus and Streptococcus thermothillus,it is difficult to separate them.According tothe different demand on pH value,Lactobacillus bulgaricus and Streptococcus thermothillus were separated by different media,and then a excellent yogurt fermentation agent was prepared by mixed Lactobacillus bulgaricus and Streptococcus thermothillus with ratio of (1~2) ∶ 1.%保加利亚乳杆菌和嗜热链球菌有共生关系,较难分离.根据保加利亚乳杆菌和嗜热链球菌对培养基pH值的不同需求,分别配制不同的培养基,将其分离开来;然后将保加利亚乳杆菌和嗜热链球菌活化菌悬液以(1~2)∶1的比例混合,制得一种优良的酸奶发酵剂.

  8. Preparation of highly (001)-oriented photoactive tungsten diselenide (WSe{sub 2}) films by an amorphous solid-liquid-crystalline solid (aSLcS) rapid-crystallization process

    Energy Technology Data Exchange (ETDEWEB)

    Bozheyev, Farabi; Friedrich, Dennis; Nie, Man; Rengachari, Mythili; Ellmer, Klaus [Helmholtz-Zentrum Berlin fuer Materialien und Energie, Institute for Solar Fuels, Hahn-Meitner-Platz 1, 14109, Berlin (Germany)

    2014-09-15

    Highly (001)-textured tungsten diselenide WSe{sub 2} thin films have been prepared by a two-step process on quartz glass and TiN metallic back contacts, respectively. At first, X-ray amorphous, selenium-rich WSe{sub 2+x} films were deposited by reactive magnetron sputtering at room temperature onto a thin metal promoter film (Ni or Pd) and afterwards annealed in an H{sub 2}Se/Ar atmosphere. X-ray diffraction and scanning electron microscopy show that highly (001)-oriented WSe{sub 2} films can be grown, which is caused by the formation of liquid promoter-metal selenide droplets which dissolve tungsten or tungsten selenide at temperatures, higher than the eutectic temperature in the promoter metal-selenium system, followed by oversaturation and eventually crystallization of WSe{sub 2} platelets. Time-resolved microwave conductivity measurements show that the films are photoactive. The sum of the carrier mobilities of the best films μ{sub e} + μ{sub h} is in the range of 1-7 cm{sup 2} V{sup -1} s{sup -1}. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Vertebrate pressure-gradient receivers.

    Science.gov (United States)

    Christensen-Dalsgaard, Jakob

    2011-03-01

    The eardrums of all terrestrial vertebrates (tetrapods) are connected through Eustachian tubes or interaural canals. In some of the animals, these connections create pressure-gradient directionality, an enhanced directionality by interaction of sound arriving at both sides of the eardrum and strongly dependent on interaural transmission attenuation. Even though the tympanic middle ear has originated independently in the major tetrapod groups, in each group the ancestral condition probably was that the two middle ears were exposed in the mouth cavity with relatively high interaural transmission. Recent vertebrates form a continuum from perfect interaural transmission (0 dB in a certain frequency band) and pronounced eardrum directionality (30-40 dB) in the lizards, over somewhat attenuated transmission and limited directionality in birds and frogs, to the strongly attenuated interaural transmission and functionally isolated pressure receiver ears in the mammals. Since some of the binaural interaction already takes place at the eardrum in animals with strongly coupled ears, producing enhanced interaural time and level differences, the subsequent neural processing may be simpler. In robotic simulations of lizards, simple binaural subtraction (EI cells, found in brainstem nuclei of both frogs and lizards) produces strongly lateralized responses that are sufficient for steering the animal robustly to sound sources.

  10. Alpha and beta dose gradients in tooth enamel

    Energy Technology Data Exchange (ETDEWEB)

    Brennan, B.J. E-mail: b.brennan@auckland.ac.nz; Prestwich, W.V.; Rink, W.J.; Marsh, R.E.; Schwarcz, H.P

    2000-12-15

    New results describing gradients in effective alpha and beta doses within a layer of tooth enamel in planar geometry are presented. The alpha (track) dose to an enamel layer is calculated using an algorithm similar to that of Aitken (Aitken, M.J., 1987. Alpha dose to a thin layer. Ancient TL 5, 1-3.). The code for ROSY version 1.4 incorporates this algorithm. The approach allows for variation of the alpha track dose near the edges of the enamel, and we describe the gradient of the alpha track dose within 40 {mu}m of each edge of the enamel for natural sources. In ESR or luminescence dating of naturally thin layers, for which stripping of the surface layer containing the alpha dose gradients may not be feasible, age estimates may change by as much as 5-10% when the detailed alpha dose calculation is included. Modern Monte Carlo-based results for the variation of beta dose for depths up to 2 mm are compared with ROSY results. For external irradiation by different sources, the attenuation of the ROSY dose estimate with depth is usually less rapid than that of the Monte Carlo-based estimate. The ROSY estimate of average beta dose to a layer in this case is between 5 and 18% higher than the Monte Carlo estimate.

  11. Gradient-driven diffusion and pattern formation in crowded mixtures

    Science.gov (United States)

    Nandigrami, Prithviraj; Grove, Brandy; Konya, Andrew; Selinger, Robin L. B.

    2017-02-01

    Gradient-driven diffusion in crowded, multicomponent mixtures is a topic of high interest because of its role in biological processes such as transport in cell membranes. In partially phase-separated solutions, gradient-driven diffusion affects microstructure, which in turn affects diffusivity; a key question is how this complex coupling controls both transport and pattern formation. To examine these mechanisms, we study a two-dimensional multicomponent lattice gas model, where "tracer" molecules diffuse between a source and a sink separated by a solution of sticky "crowder" molecules that cluster to form dynamically evolving obstacles. In the high-temperature limit, crowders and tracers are miscible, and transport may be predicted analytically. At intermediate temperatures, crowders phase separate into clusters that drift toward the tracer sink. As a result, steady-state tracer diffusivity depends nonmonotonically on both temperature and crowder density, and we observe a variety of complex microstructures. In the low-temperature limit, crowders rapidly aggregate to form obstacles that are kinetically arrested; if crowder density is near the percolation threshold, resulting tracer diffusivity shows scaling behavior with the same scaling exponent as the random resistor network model. Though highly idealized, this simple model reveals fundamental mechanisms governing coupled gradient-driven diffusion, phase separation, and microstructural evolution in crowded mixtures.

  12. Preparation of low flow-resistant methacrylate-based monolithic stationary phases of different hydrophobicity and the application to rapid reversed-phase liquid chromatographic separation of alkylbenzenes at high flow rate and elevated temperature.

    Science.gov (United States)

    Ueki, Yuji; Umemura, Tomonari; Iwashita, Yoshikazu; Odake, Tamao; Haraguchi, Hiroki; Tsunoda, Kin-ichi

    2006-02-17

    Low flow-resistant alkyl methacrylate-based monolithic stationary phases of different hydrophobicity were constructed for reversed-phase capillary liquid chromatography by thermally initiated radical polymerization of respective methacrylate ester monomer with different alkyl chain (C2, C4, C6, C12, C18) and ethylene glycol dimethacrylate (EDMA) in a 250 microm i.d. fused silica capillary. The hydrophobicity was basically controlled by changing the length and/or the density of the alkyl-chain, while the composition and the ratio of porogenic solvent were adjusted to obtain highly permeable rigid monoliths with adequate column efficiency. Among the prepared monolithic stationary phases, C18-methacrylate monoliths polymerized from a binary porogenic solvent of isoamyl alcohol and 1,4-buthandiol exhibited the most promising performance in terms of hydraulic resistance and column efficiency. The pressure drops of 20-cm long monolithic columns were below approximately 0.4 MPa at a normal linear velocity of 1mm/s (a flow rate of 3 microL/min), and the numbers of theoretical plates for alkylbenzenes mostly exceeded 3000 plates/20 cm. The produced monolithic columns had good mechanical strength for high pressure and temperature, and could be properly operated even at a temperature of 80 degrees C and at a pressure of at least 33 MPa. At 80 degrees C, the theoretical plate numbers reached 6000 plates/20 cm because of the enhanced mass transfer. Due to the novel hydraulic resistance and mechanical strength, the separation time could be reduced 120-fold simply by raising the flow rate and column temperature.

  13. Preparation of magnetic graphene/mesoporous silica composites with phenyl-functionalized pore-walls as the restricted access matrix solid phase extraction adsorbent for the rapid extraction of parabens from water-based skin toners.

    Science.gov (United States)

    Feng, Jianan; He, Xinying; Liu, Xiaodan; Sun, Xueni; Li, Yan

    2016-09-23

    In this work, phenyl-functionalized magnetic graphene/mesoporous silica composites (MG-mSiO2-Ph) were prepared and applied as restricted access matrix solid phase extraction (RAM-SPE) adsorbents to determine the parabens in commercially available retail cosmetics. MG-mSiO2-Ph composites were synthesized by a surfactant-mediated co-condensation reaction in which mesoporous silica with phenyl-functionalized pore-walls was coated on a magnetic graphene sheet. The obtained nano-composites were proven to be of sufficient quality for an ideal RAM-SPE adsorbent with a large specific surface area of 369m(2)g(-1), uniform mesopores of 2.8nm, and special phenyl-functionalized pore-walls. Parabens, such as methyl paraben, ethyl paraben and propyl paraben, were extracted from water-based skin toners using one step of the RAM-SPE and were then analysed by a HPLC-DAD system. The SPE conditions were optimized by studying the parameters, such as the adsorbent amount, elution solvent type, adsorption time and desorption time, that influence the extraction efficiency. For each analyte, there were good linearities of approximately 0.10-120μgmL(-1) with determination coefficients (R(2))>0.995. The sensitivity was as low as 0.01-0.025μgmL(-1) for the LOD, and the percent recoveries were 98.37-105.84%. The intra-day and inter-day RSDs were 1.44-6.11% (n=6) and 3.12-11.70% (n=6), respectively. The results indicated that this method with novel RAM-SPE adsorbents is sensitive and convenient. The results also offered an attractive alternative for the extraction and determination of paraben preservatives in a complex matrix, such as cosmetics. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Improving the gradient in least-squares reverse time migration

    Science.gov (United States)

    Liu, Qiancheng

    2016-04-01

    Least-squares reverse time migration (LSRTM) is a linearized inversion technique used for estimating high-wavenumber reflectivity. However, due to the redundant overlay of the band-limited source wavelet, the gradient based on the cross-correlated imaging principle suffers from a loss of wavenumber information. We first prepare the residuals between observed and demigrated data by deconvolving with the amplitude spectrum of the source wavelet, and then migrate the preprocessed residuals by using the cross-correlation imaging principle. In this way, a gradient that preserves the spectral signature of data residuals is obtained. The computational cost of source-wavelet removal is negligible compared to that of wavefield simulation. The two-dimensional Marmousi model containing complex geology structures is considered to test our scheme. Numerical examples show that our improved gradient in LSRTM has a better convergence behavior and promises inverted results of higher resolution. Finally, we attempt to update the background velocity with our inverted velocity perturbations to approach the true velocity.

  15. Newton's method in the context of gradients

    Directory of Open Access Journals (Sweden)

    John W. Neuberger

    2007-09-01

    Full Text Available This paper gives a common theoretical treatment for gradient and Newton type methods for general classes of problems. First, for Euler-Lagrange equations Newton's method is characterized as an (asymptotically optimal variable steepest descent method. Second, Sobolev gradient type minimization is developed for general problems using a continuous Newton method which takes into account a "boundary condition" operator.

  16. An Inexpensive Digital Gradient Controller for HPLC.

    Science.gov (United States)

    Brady, James E.; Carr, Peter W.

    1983-01-01

    Use of gradient elution techniques in high performance liquid chromatography (HPLC) is often essential for direct separation of complex mixtures. Since most commercial controllers have features that are of marginal value for instructional purposes, a low-cost controller capable of illustrating essential features of gradient elution was developed.…

  17. NUMERICAL METHODS IN MARINE ECOLOGY 2. GRADIENT ...

    African Journals Online (AJOL)

    GRADIENT ANALYSIS OF ROCKY SHORE SAMPL~S FROM FALSE BAY ... could be applied to marine studies and it showed quantitatively that the fauna varied with changes ... tigator and the computational facilities at his disposal. ... the major environmental gradients affecting distribution in a more complex situation with.

  18. An Inexpensive Digital Gradient Controller for HPLC.

    Science.gov (United States)

    Brady, James E.; Carr, Peter W.

    1983-01-01

    Use of gradient elution techniques in high performance liquid chromatography (HPLC) is often essential for direct separation of complex mixtures. Since most commercial controllers have features that are of marginal value for instructional purposes, a low-cost controller capable of illustrating essential features of gradient elution was developed.…

  19. A numerical study of scalar gradients in Kelvin-Helmholtz billows

    Science.gov (United States)

    Parker, J. W.; Bowhill, S. A.

    1989-01-01

    A high resolution numerical technique is used to model the development of a periodically perturbed shear layer imbedded in an initially vertical gradient of a passive scalar. The technique follows the development of the vorticity through an initial linear growth state and well into the nonlinear development of Kelvin-Helmholtz billows, in the zero-viscosity, zero-diffusion limit. The resulting scalar distribution rapidly develops regions of extremely sharp scalar gradients, which wind around the periodically spaced vortical low gradient cores. Vertical cross sections through different parts of the billow structure are presented and compared with rocket measurements of electron density fine structure in the mesosphere. Gradient limits imposed by finite diffusion are calculated, and implications for atmospheric radar observations are discussed.

  20. Density Gradient Stabilization of Electron Temperature Gradient Driven Turbulence in a Spherical Tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Y; Mazzucato, E; Guttenfelder, W; Bell, R E; Domier, C W; LeBlanc, B P; Lee, K C; Luhmann Jr, N C; Smith, D R

    2011-03-21

    In this letter we report the first clear experimental observation of density gradient stabilization of electron temperature gradient driven turbulence in a fusion plasma. It is observed that longer wavelength modes, k⊥ρs ≤10, are most stabilized by density gradient, and the stabilization is accompanied by about a factor of two decrease in the plasma effective thermal diffusivity.

  1. Solution preparation

    Energy Technology Data Exchange (ETDEWEB)

    Seitz, M.G.

    1982-01-01

    Reviewed in this statement are methods of preparing solutions to be used in laboratory experiments to examine technical issues related to the safe disposal of nuclear waste from power generation. Each approach currently used to prepare solutions has advantages and any one approach may be preferred over the others in particular situations, depending upon the goals of the experimental program. These advantages are highlighted herein for three approaches to solution preparation that are currently used most in studies of nuclear waste disposal. Discussion of the disadvantages of each approach is presented to help a user select a preparation method for his particular studies. Also presented in this statement are general observations regarding solution preparation. These observations are used as examples of the types of concerns that need to be addressed regarding solution preparation. As shown by these examples, prior to experimentation or chemical analyses, laboratory techniques based on scientific knowledge of solutions can be applied to solutions, often resulting in great improvement in the usefulness of results.

  2. High order compact schemes for gradient approximation

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In this paper, we propose three gradient recovery schemes of higher order for the linear interpolation. The first one is a weighted averaging method based on the gradients of the linear interpolation on the uniform mesh, the second is a geometric averaging method constructed from the gradients of two cubic interpolation on macro element, and the last one is a local least square method on the nodal patch with cubic polynomials. We prove that these schemes can approximate the gradient of the exact solution on the symmetry points with fourth order. In particular, for the uniform mesh, we show that these three schemes are the same on the considered points. The last scheme is more robust in general meshes. Consequently, we obtain the superconvergence results of the recovered gradient by using the aforementioned results and the supercloseness between the finite element solution and the linear interpolation of the exact solution. Finally, we provide several numerical experiments to illustrate the theoretical results.

  3. Dual fuel gradients in uranium silicide plates

    Energy Technology Data Exchange (ETDEWEB)

    Pace, B.W. [Babock and Wilcox, Lynchburg, VA (United States)

    1997-08-01

    Babcock & Wilcox has been able to achieve dual gradient plates with good repeatability in small lots of U{sub 3}Si{sub 2} plates. Improvements in homogeneity and other processing parameters and techniques have allowed the development of contoured fuel within the cladding. The most difficult obstacles to overcome have been the ability to evaluate the bidirectional fuel loadings in comparison to the perfect loading model and the different methods of instilling the gradients in the early compact stage. The overriding conclusion is that to control the contour of the fuel, a known relationship between the compact, the frames and final core gradient must exist. Therefore, further development in the creation and control of dual gradients in fuel plates will involve arriving at a plausible gradient requirement and building the correct model between the compact configuration and the final contoured loading requirements.

  4. A new family of conjugate gradient methods

    Science.gov (United States)

    Shi, Zhen-Jun; Guo, Jinhua

    2009-02-01

    In this paper we develop a new class of conjugate gradient methods for unconstrained optimization problems. A new nonmonotone line search technique is proposed to guarantee the global convergence of these conjugate gradient methods under some mild conditions. In particular, Polak-Ribiére-Polyak and Liu-Storey conjugate gradient methods are special cases of the new class of conjugate gradient methods. By estimating the local Lipschitz constant of the derivative of objective functions, we can find an adequate step size and substantially decrease the function evaluations at each iteration. Numerical results show that these new conjugate gradient methods are effective in minimizing large-scale non-convex non-quadratic functions.

  5. pH gradients induced by urea metabolism in 'artificial mouth' microcosm plaques.

    Science.gov (United States)

    Sissons, C H; Wong, L; Hancock, E M; Cutress, T W

    1994-06-01

    Evidence was sought for urea-induced pH gradients in dental plaque microcosm biofilms cultured from the mixed salivary bacteria in a multi plaque 'artificial mouth'. Application of 500 mmol/l urea for short periods (6 min) to 5-8 mm maximum-thickness plaques induced intraplaque pH gradients of up to 0.7 pH units with the surface alkaline relative to the inner plaque. These pH gradients persisted for more than 5 h in the absence of a flow of fluid. With 30-min urea applications and a flow of a basal medium containing mucin (BMM, pH 7.0), the pH of the inner (deeper) plaque regions also increased. Although the pH gradient initially formed was alkaline at the plaque surface, the BMM flow lowered the surface pH to neutrality whilst the inner layers were still alkaline, thereby reversing the pH gradient. In thick microcosm dental plaques, urea-induced pH gradients can therefore form and last many hours. They probably result from the significant time taken for urea to penetrate to the inner layers of plaque, its rapid metabolism by the outer plaque layers, and a rate-limiting clearance of ammonia. Even a slow BMM flow over the plaque greatly increased the rate of return to the resting pH, causing the gradients to change polarity.

  6. Computer-assisted multi-segment gradient optimization in ion chromatography.

    Science.gov (United States)

    Tyteca, Eva; Park, Soo Hyun; Shellie, Robert A; Haddad, Paul R; Desmet, Gert

    2015-02-13

    This study reports simulation and optimization of ion chromatography separations using multi-segment gradient elution. First, an analytical expression for the gradient retention factor under these complex elution profiles was derived. This allows a rapid retention time prediction calculations under different gradient conditions, during computer-assisted method development. Next, these analytical expressions were implemented in an in-house written Matlab(®) routine that searches for the optimal (multi-segment) gradient conditions, either via a four-segment grid search or via the recently proposed one-segment-per-component search, in which the slope is adjusted after the elution of each individual component. Evaluation of the retention time simulation and optimization approaches was performed on a mixture of 18 inorganic anions and different subsets with varying number of compounds. The two considered multi-segment gradient optimization searches resulted in similar proposed gradient profiles, and corresponding chromatograms. Moreover, the resultant chromatograms were clearly superior to the chromatograms obtained from the best simple linear gradient profiles, found via a fine grid search. The proposed approach is useful for automated method development in ion chromatography in which complex elution profiles are often used to increase the separation power.

  7. Effect of modulator sorption on gradient shape in ion-exchange chromatography

    Science.gov (United States)

    Velayudhan, A.; Ladisch, M. R.; Mitchell, C. A. (Principal Investigator)

    1995-01-01

    Mobile phase additives, or modulators, are used in gradient elution chromatography to facilitate separation and reduce separation time. The modulators are usually assumed to be linearly adsorbed or unadsorbed. Here, the consequences of nonlinear modulator adsorption are examined for ion-exchange gradient elution through a series of simulations. Even when the buffer salt is identical to the modulator salt, gradient deformation is observed; the extent of deformation increases as the volume of the feed is increased. When the modulator salt is different from the buffer salt, unusual effects are observed, and the chromatograms are quite different from those predicted by classical gradient elution theory. In particular, local increases in the buffer concentration are found between feed bands, and serve to improve the separation. These effects become more pronounced as the feed volume increases, and could therefore prove valuable in preparative applications.

  8. Microstructure and phase transformation behavior of Mo-MoSi2 gradient material

    Institute of Scientific and Technical Information of China (English)

    Ying-Yi Zhang; Yun-Gang Li; Yong-Hong Qi; Xue-Feng Shi

    2015-01-01

    Mo-MoSi2 gradient coating on Mo substrate was prepared by siliconizing process,using the polysilicon as silicon atoms.The gradient layer was analyzed by the experimental results,theoretical analysis,and thermodynamic calculation.The silicon,molybdenum content of gradient coating shows a gradual change regulation.The reaction between silicon and molybdenum is most likely to generate Mo5Si3,then MoSi2,finally Mo3Si,but when the silicon content is excessive,the Mo5Si3 and Mo3Si will react with silicon and generate MoSi2.The gradient layer is mainly constituted by Si and MoSi2,only about 1/10 gradient layer is constituted by Mo5Si3 and Mo3Si,and the stable existences of Mo5Si3 and Mo3Si are mainly determined by the silicon content.Along the Mo substrate to the surface of the coating,the phase compo sition of gradient coating changes as follows:Mo → transition layer,Mo (main phase) + Mo3Si + Mo5Si3 →intermediate layer,and MoSi2 (main phase)+ Mo5Si3 + Si → surface layer MoSi2 (main phase)+ Si,and the experimental temperature has no effect on phase composition of gradient coating.

  9. Cell Growth on ("Janus") Density Gradients of Bifunctional Zeolite L Crystals.

    Science.gov (United States)

    Kehr, Nermin Seda; Motealleh, Andisheh; Schäfer, Andreas H

    2016-12-28

    Nanoparticle density gradients on surfaces have attracted interest as two-dimensional material surfaces that can mimic the complex nano-/microstructure of the native extracellular matrix, including its chemical and physical gradients, and can therefore be used to systematically study cell-material interactions. In this respect, we report the preparation of density gradients made of bifunctional zeolite L crystals on glass surfaces and the effects of the density gradient and biopolymer functionalization of zeolite L crystals on cell adhesion. We also describe how we created "Janus" density gradient surfaces by gradually depositing two different types of zeolite L crystals that were functionalized and loaded with different chemical groups and guest molecules onto the two distinct sides of the same glass substrate. Our results show that more cells adhered on the density gradient of biopolymer-coated zeolites than on uncoated ones. The number of adhered cells increased up to a certain surface coverage of the glass by the zeolite L crystals, but then it decreased beyond the zeolite density at which a higher surface coverage decreased fibroblast cell adhesion and spreading. Additionally, cell experiments showed that cells gradually internalized the guest-molecule-loaded zeolite L crystals from the underlying density gradient containing bifunctional zeolite L crystals.

  10. Bending efficiency through property gradients in bamboo, palm, and wood-based composites.

    Science.gov (United States)

    Wegst, Ulrike G K

    2011-07-01

    Nature, to a greater extent than engineering, takes advantage of hierarchical structures. These allow for optimization at each structural level to achieve mechanical efficiency, meaning mechanical performance per unit mass. Palms and bamboos do this exceptionally well; both are fibre-reinforced cellular materials in which the fibres are aligned parallel to the stem or culm, respectively. The distribution of these fibres is, however, not uniform: there is a density and modulus gradient across the section. This property gradient increases the flexural rigidity of the plants per unit mass, mass being a measure of metabolic investment made into an organism's construction. An analytical model is presented with which a 'gradient shape factor' can be calculated that describes by how much a plant's bending efficiency is increased through gradient structures. Combining the 'gradient shape factor' with a 'microstructural shape factor' that captures the efficiency gained through the cellular nature of the fibre composite's matrix, and a 'macroscopical shape factor' with which the tubular shape of bamboo can be described, for example, it is possible to explore how much each of these three structural levels of the hierarchy contributes to the overall bending performance of the stem or culm. In analogy, the bending efficiency of the commonly used wood-based composite medium-density fibreboard can be analysed; its property gradient is due to its manufacture by hot pressing. A few other engineered materials exist that emulate property gradients; new manufacturing routes to prepare them are currently being explored. It appears worthwhile to pursue these further.

  11. In vitro comparison of Doppler and catheter-measured pressure gradients in 3D models of mitral valve calcification.

    Science.gov (United States)

    Herrmann, Tarrah A; Siefert, Andrew W; Pressman, Gregg S; Gollin, Hannah R; Touchton, Steven A; Saikrishnan, Neelakantan; Yoganathan, Ajit P

    2013-09-01

    Mitral annular calcification (MAC) involves calcium deposition in the fibrous annulus supporting the mitral valve (MV). When calcification extends onto the leaflets, valve opening can be restricted. The influence of MAC MV geometry on Doppler gradients is unknown. This study describes a novel methodology to rapid-prototype subject-specific MAC MVs. Replicated valves were used to assess the effects of distorted annular-leaflet geometry on Doppler-derived, transmitral gradients in comparison to direct pressure measurements and to determine if transmitral gradients vary according to measurement location. Three-dimensional echocardiography data sets were selected for two MAC MVs and one healthy MV. These MVs were segmented and rapid prototyped in their middiastolic configuration for in vitro testing. The effects of MV geometry, measurement modality, and measurement location on transmitral pressure gradient were assessed by Doppler and catheter at three locations along the MV's intercommissural axis. When comparing dimensions of the rapid-prototyped valves to the subject echocardiography data sets, mean relative errors ranged from 6.2% to 35%. For the evaluated MVs, Doppler pressure gradients exhibited good agreement with catheter-measured gradients at a variety of flow rates, though with slight systematic overestimation in the recreated MAC valves. For all of the tested MVs, measuring the transmitral pressure gradient at differing valve orifice positions had minimal impact on observed gradients. Upon the testing of additional normal and calcific MVs, these data may contribute to an improved clinical understanding of MAC-related mitral stenosis. Moreover, they provide the ability to statistically evaluate between measurement locations, flow rates, and valve geometries for Doppler-derived pressure gradients. Determining these end points will contribute to greater clinical understanding for the diagnosis MAC patients and understanding the use and application of Doppler

  12. Platelet adhesion onto wettability gradient surfaces in the absence and presence of plasma proteins.

    Science.gov (United States)

    Lee, J H; Lee, H B

    1998-08-01

    A wettability gradient was prepared on lowdensity polyethylene (PE) sheets by treating them in air with a corona from a knife-type electrode the power of which increased gradually along the sample length. The PE surfaces oxidized gradually with the increasing corona power and a wettability gradient was created on the surfaces, as evidenced by the measurement of water contact angles, Fourier transform infrared spectroscopy in the attenuated total reflectance mode, and electron spectroscopy for chemical analysis. The wettability gradient surfaces prepared were used to investigate the adhesion behavior of platelets in the absence and presence of plasma proteins in terms of the surface hydrophilicity/hydrophobicity of polymeric materials. The platelets adhered to the wettability gradient surfaces along the sample length were counted and examined by scanning electron microscopy (SEM). It was observed that the platelet adhesion in the absence of plasma proteins increased gradually as the surface wettability increased along the sample length. The platelets adhered to the hydrophilic positions of the gradient surface also were more activated (possessed more pseudo pods as examined by SEM) than on the more hydrophobic ones. However, platelet adhesion in the presence of plasma proteins decreased gradually with the increasing surface wettability; the platelets adhered to the surface also were more activated on the hydrophobic positions of the gradient surface. This result is closely related to plasma protein adsorption on the surface. Plasma protein adsorption on the wettability gradient surface increased with the increasing surface wettability. More plasma protein adsorption on the hydrophilic positions of the gradient surface caused less platelet adhesion, probably due to platelet adhesion inhibiting proteins, such as high-molecular-weight kininogen, which preferably adsorbs onto the surface by the so-called Vroman effect. It seems that both the presence of plasma proteins

  13. Rapid Formation of Cerebral Microbleeds after Carotid Artery Stenting

    OpenAIRE

    Kousuke Kakumoto; Shoji Matsumoto; Ichiro Nakahara; Yoshihiko Watanabe; Yutaka Fukushima; Urabe Yoshikiyo; Ryota Ishibashi; Masanori Gomi; Keiichi Tsuji; Yoshinori Sanbongi; Tetsuya Hashimoto; Yujiro Tanaka; Takeshi Yamada; Jun-ichi Kira

    2012-01-01

    Background: Recent studies reported that cerebral microbleeds (CMBs), i.e. small areas of signal loss on T2*-weighted gradient-echo (GE) imaging, could develop rapidly after acute ischemic stroke. We hypothesized that CMBs rapidly emerge after carotid artery stenting (CAS). Objective: We investigated the frequency of and predisposing factors for CMBs after CAS. Methods: We retrospectively examined MRI before and after CAS in 88 consecutive patients (average age: 71.7 ± 7.2 years, average rate...

  14. Rapid response systems update.

    Science.gov (United States)

    Winterbottom, Fiona; Castex, Julie; Campbell, Anita

    2013-06-01

    Rapid response is a mature concept that is undergoing metamorphosis. The ideal structure and function of these safety teams has not yet been realized but new developments in the field of rapid response systems are evolving.

  15. Intracellular chemical gradients: morphing principle in bacteria

    Directory of Open Access Journals (Sweden)

    Endres Robert G

    2012-09-01

    Full Text Available Abstract Advances in computational biology allow systematic investigations to ascertain whether internal chemical gradients can be maintained in bacteria – an open question at the resolution limit of fluorescence microscopy. While it was previously believed that the small bacterial cell size and fast diffusion in the cytoplasm effectively remove any such gradient, a new computational study published in BMC Biophysics supports the emerging view that gradients can exist. The study arose from the recent observation that phosphorylated CtrA forms a gradient prior to cell division in Caulobacter crescentus, a bacterium known for its complicated cell cycle. Tropini et al. (2012 postulate that such gradients can provide an internal chemical compass, directing protein localization, cell division and cell development. More specifically, they describe biochemical and physical constraints on the formation of such gradients and explore a number of existing bacterial cell morphologies. These chemical gradients may limit in vitro analyses, and may ensure timing control and robustness to fluctuations during critical stages in cell development.

  16. Satellite gravity gradient grids for geophysics.

    Science.gov (United States)

    Bouman, Johannes; Ebbing, Jörg; Fuchs, Martin; Sebera, Josef; Lieb, Verena; Szwillus, Wolfgang; Haagmans, Roger; Novak, Pavel

    2016-02-11

    The Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite aimed at determining the Earth's mean gravity field. GOCE delivered gravity gradients containing directional information, which are complicated to use because of their error characteristics and because they are given in a rotating instrument frame indirectly related to the Earth. We compute gravity gradients in grids at 225 km and 255 km altitude above the reference ellipsoid corresponding to the GOCE nominal and lower orbit phases respectively, and find that the grids may contain additional high-frequency content compared with GOCE-based global models. We discuss the gradient sensitivity for crustal depth slices using a 3D lithospheric model of the North-East Atlantic region, which shows that the depth sensitivity differs from gradient to gradient. In addition, the relative signal power for the individual gradient component changes comparing the 225 km and 255 km grids, implying that using all components at different heights reduces parameter uncertainties in geophysical modelling. Furthermore, since gravity gradients contain complementary information to gravity, we foresee the use of the grids in a wide range of applications from lithospheric modelling to studies on dynamic topography, and glacial isostatic adjustment, to bedrock geometry determination under ice sheets.

  17. Rapid Reading, Yes

    Science.gov (United States)

    Frommer, Harvey

    1971-01-01

    Recommends instruction in rapid reading fo high school and college students and asserts that flexibility of speed and reasoning provide the foundation for effective rapid reading. Describes the components of rapid reading as orientation, selection, clarification, arrangement, review, and study. (RW)

  18. A Resistivity Gradient Piezoelectric FGM Actuator

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A resistivity gradient actuator based on lead zirconate titanate ceramics was successfully developed and the bending deflections up to 140 μm were obtained. The actuator material was a matrix of PZT ceramic into which smooth gradient of piezoelectric activity was introduced. The application of an electric field then causes the actuator to bend due to differential strains induced by the piezoelectric effect. The resistivity gradient of the actuator was achieved by doping PZT with suitable donor and acceptor dopants. PZT powder was modified and synthesized by using two stage powder fabrication method. The actuator was fabricated by uniaxial pressing followed by isostatic pressing with two layers of different resistivities.

  19. Discussion of liquid threshold pressure gradient

    Directory of Open Access Journals (Sweden)

    Xiukun Wang

    2017-06-01

    The correct interpretation is that there are two flow regimes: nonlinear flow regime (non-Darcy flow regime when the pressure gradients are low, and linear flow regime (Darcy flow regime when the pressure gradient is intermediate or high. The nonlinear flow regime starts from the origin point. As the pressure gradient is increased, the curve becomes a straight line demonstrating the linear flow regime. We have verified our views by first analyzing the causes of non-Darcy flow, and then systematically analyzed typical experimental data and correlations in the literature. We conclude that TPG does not exist. We also use several counter examples to support our conclusion.

  20. GRADIENT ENERGY DETECTION OF LSB STEGANOGRAPHY

    Institute of Scientific and Technical Information of China (English)

    Li Zhi; Sui Aifen; Niu Xinxin; Yang Yixian

    2005-01-01

    The spatial Least Significant Bit (LSB) steganography results in the alteration of the smooth characteristics between adjoining pixels of the raw image. The relation between the length of embedded message and the gradient energy is theoretically analyzed, and then a steganalysis and detection method, named Gradient Energy-Flipping Rate (GEFR) detection is proposed. Based on the analysis of the variation of the gradient energy, which results from the LSB steganography in color and grayscale image, the secret message embedded in the target image is detected, and the length of the embedded message is estimated. The method is proved effective and accurate by simulation (detection rate reaches 0.01bit per pixel).

  1. Colour and stellar population gradients in galaxies

    CERN Document Server

    Tortora, C; Cardone, V F; Capaccioli, M; Jetzer, P; Molinaro, R

    2010-01-01

    We discuss the colour, age and metallicity gradients in a wide sample of local SDSS early- and late-type galaxies. From the fitting of stellar population models we find that metallicity is the main driver of colour gradients and the age in the central regions is a dominant parameter which rules the scatter in both metallicity and age gradients. We find a consistency with independent observations and a set of simulations. From the comparison with simulations and theoretical considerations we are able to depict a general picture of a formation scenario.

  2. Strain gradient effects in surface roughening

    DEFF Research Database (Denmark)

    Borg, Ulrik; Fleck, N.A.

    2007-01-01

    A thin aluminium sheet comprising of large polycrystals is pulled in uniaxial tension and the resulting surface profile is measured in a scanning electron microscope. The surface profile near the grain boundaries reveals a local deformation pattern of width of a few micrometres and is strong...... evidence for strain gradient effects. Numerical analyses of a bicrystal undergoing in-plane tensile deformation are also studied using a strain gradient crystal plasticity theory and also by using a strain gradient plasticity theory for an isotropic solid. Both theories include an internal material length...

  3. Speciation gradients and the distribution of biodiversity.

    Science.gov (United States)

    Schluter, Dolph; Pennell, Matthew W

    2017-05-31

    Global patterns of biodiversity are influenced by spatial and environmental variations in the rate at which new species form. We relate variations in speciation rates to six key patterns of biodiversity worldwide, including the species-area relationship, latitudinal gradients in species and genetic diversity, and between-habitat differences in species richness. Although they sometimes mirror biodiversity patterns, recent rates of speciation, at the tip of the tree of life, are often highest where species richness is low. Speciation gradients therefore shape, but are also shaped by, biodiversity gradients and are often more useful for predicting future patterns of biodiversity than for interpreting the past.

  4. Colour and stellar population gradients in galaxies

    Science.gov (United States)

    Tortora, C.; Napolitano, N. R.; Cardone, V. F.; Capaccioli, M.; Jetzer, P.; Molinaro, R.

    We discuss the colour, age and metallicity gradients in a wide sample of local SDSS early- and late-type galaxies. From the fitting of stellar population models we find that metallicity is the main driver of colour gradients and the age in the central regions is a dominant parameter which rules the scatter in both metallicity and age gradients. We find a consistency with independent observations and a set of simulations. From the comparison with simulations and theoretical considerations we are able to depict a general picture of a formation scenario.

  5. Droplet Motion on a Shape Gradient Surface.

    Science.gov (United States)

    Zheng, Yanfen; Cheng, Jiang; Zhou, Cailong; Xing, Haiting; Wen, Xiufang; Pi, Pihui; Xu, Shouping

    2017-05-02

    We demonstrate a facile method to induce water droplet motion on an wedge-shaped superhydrophobic copper surface combining with a poly(dimethylsiloxane) (PDMS) oil layer on it. The unbalanced interfacial tension from the shape gradient offers the actuating force. The superhydrophobicity critically eliminates the droplet contact line pinning and the slippery PDMS oil layer lubricates the droplet motion, which makes the droplet move easily. The maximum velocity and furthest position of droplet motion were recorded and found to be influenced by the gradient angle. The mechanism of droplet motion on the shape gradient surface is systematically discussed, and the theoretical model analysis is well matched with the experimental results.

  6. Preparation of tungsten oxide

    Science.gov (United States)

    Bulian, Christopher J.; Dye, Robert C.; Son, Steven F.; Jorgensen, Betty S.; Perry, W. Lee

    2009-09-22

    Tungsten trioxide hydrate (WO.sub.3.H.sub.2O) was prepared from a precursor solution of ammonium paratungstate in concentrated aqueous hydrochloric acid. The precursor solution was rapidly added to water, resulting in the crash precipitation of a yellow white powder identified as WO.sub.3.H.sub.2O nanosized platelets by x-ray diffraction and scanning electron microscopy. Annealing of the powder at 200.degree. C. provided cubic phase WO.sub.3 nanopowder, and at 400.degree. C. provided WO.sub.3 nanopowder as a mixture of monoclinic and orthorhombic phases.

  7. Difluoromethane preparation

    NARCIS (Netherlands)

    Wiersma, A.; Sandt, E.J.A.; Van Bekkum, H.; Makkee, M.; Moulijn, J.A.

    1996-01-01

    Abstract of NL 9401574 (A) The invention relates to a method for preparing difluoromethane, wherein dichlorodifluoromethane or monochlorodifluoromethane is brought into contact with hydrogen in the presence of palladium on activated carbon, wherein the loading of the palladium on the activated c

  8. Vegetation patterns and environmental gradients in Benin

    NARCIS (Netherlands)

    Adomou, A.

    2005-01-01

    Key words: West Africa, Benin, vegetation patterns, floristic areas, phytogeography, chorology, floristic gradients, climatic factors, water availability, Dahomey Gap, threatened plants, biodiversity, conservation.Understanding plant species distribution patterns and the underlying factors is a cruc

  9. Unimodal and crossmodal gradients of spatial attention

    DEFF Research Database (Denmark)

    Föcker, J.; Hötting, K.; Gondan, Matthias

    2010-01-01

    Behavioral and event-related potential (ERP) studies have shown that spatial attention is gradually distributed around the center of the attentional focus. The present study compared uni- and crossmodal gradients of spatial attention to investigate whether the orienting of auditory and visual...... spatial attention is based on modality specific or supramodal representations of space. Auditory and visual stimuli were presented from five speaker locations positioned in the right hemifield. Participants had to attend to the innermost or outmost right position in order to detect either visual...... or auditory deviant stimuli. Detection rates and event-related potentials (ERPs) indicated that spatial attention is distributed as a gradient. Unimodal spatial ERP gradients correlated with the spatial resolution of the modality. Crossmodal spatial gradients were always broader than the corresponding...

  10. Full Gradient Solution to Adaptive Hybrid Control

    Science.gov (United States)

    Bean, Jacob; Schiller, Noah H.; Fuller, Chris

    2017-01-01

    This paper focuses on the adaptation mechanisms in adaptive hybrid controllers. Most adaptive hybrid controllers update two filters individually according to the filtered reference least mean squares (FxLMS) algorithm. Because this algorithm was derived for feedforward control, it does not take into account the presence of a feedback loop in the gradient calculation. This paper provides a derivation of the proper weight vector gradient for hybrid (or feedback) controllers that takes into account the presence of feedback. In this formulation, a single weight vector is updated rather than two individually. An internal model structure is assumed for the feedback part of the controller. The full gradient is equivalent to that used in the standard FxLMS algorithm with the addition of a recursive term that is a function of the modeling error. Some simulations are provided to highlight the advantages of using the full gradient in the weight vector update rather than the approximation.

  11. On lower order strain gradient plasticity theories

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Hutchinson, J. W.

    2002-01-01

    By way of numerical examples, this paper explores the nature of solutions to a class of strain gradient plasticity theories that employ conventional stresses, equilibrium equations and boundary conditions. Strain gradients come into play in these modified conventional theories only to alter the t...... the tangential moduli governing increments of stress and strain. It is shown that the modification is far from benign from a mathematical standpoint, changing the qualitative character of solutions and leading to a new type of localization that appears to be unphysical.......By way of numerical examples, this paper explores the nature of solutions to a class of strain gradient plasticity theories that employ conventional stresses, equilibrium equations and boundary conditions. Strain gradients come into play in these modified conventional theories only to alter...

  12. Improving GOCE cross-track gravity gradients

    Science.gov (United States)

    Siemes, Christian

    2017-07-01

    The GOCE gravity gradiometer measured highly accurate gravity gradients along the orbit during GOCE's mission lifetime from March 17, 2009, to November 11, 2013. These measurements contain unique information on the gravity field at a spatial resolution of 80 km half wavelength, which is not provided to the same accuracy level by any other satellite mission now and in the foreseeable future. Unfortunately, the gravity gradient in cross-track direction is heavily perturbed in the regions around the geomagnetic poles. We show in this paper that the perturbing effect can be modeled accurately as a quadratic function of the non-gravitational acceleration of the satellite in cross-track direction. Most importantly, we can remove the perturbation from the cross-track gravity gradient to a great extent, which significantly improves the accuracy of the latter and offers opportunities for better scientific exploitation of the GOCE gravity gradient data set.

  13. Optimizing sampling approaches along ecological gradients

    DEFF Research Database (Denmark)

    Schweiger, Andreas; Irl, Severin D. H.; Steinbauer, Manuel

    2016-01-01

    1. Natural scientists and especially ecologists use manipulative experiments or field observations along gradients to differentiate patterns driven by processes from those caused by random noise. A well-conceived sampling design is essential for identifying, analysing and reporting underlying...

  14. Integral Field Spectroscopy Surveys: Oxygen Abundance Gradients

    Science.gov (United States)

    Sánchez, S. F.; Sánchez-Menguiano, L.

    2017-07-01

    We present here the recent results on our understanding of oxygen abundance gradients derived using Integral Field Spectroscopic surveys. In particular we analyzed more than 2124 datacubes corresponding to individual objects observed by the CALIFA (˜ 734 objects) and the public data by MaNGA (˜ 1390 objects), deriving the oxygen abundance gradient for each galaxy. We confirm previous results that indicate that the shape of this gradient is very similar for all galaxies with masses above 109.5M⊙, presenting in average a very similar slope of ˜ -0.04 dex within 0.5-2.0 re, with a possible drop in the inner regions (r109.5M⊙) the gradient seems to be flatter than for more massive ones. All these results agree with an inside-out growth of massive galaxies and indicate that low mass ones may still be growing in an outside in phase.

  15. Artificial photosynthesis: Light-activated calcium gradients

    Science.gov (United States)

    Thompson, David H.

    2002-12-01

    Photosynthetic organisms use light to create chemical gradients across bilayer membranes that drive energetically unfavourable reactions. Synthetic systems that accomplish the same feat may find uses in a variety of biological and non-biological applications.

  16. CMB Anisotropies from a Gradient Mode

    CERN Document Server

    Mirbabayi, Mehrdad

    2014-01-01

    A pure gradient mode must have no observable dynamical effect at linear level. We confirm this by showing that its contribution to the dipolar power asymmetry of CMB anisotropies vanishes, if Maldacena's consistency condition is satisfied. To this end, the existing second order Sachs-Wolfe formula in the squeezed limit is extended to include a gradient in the long mode and to account for the change in the location of the last scattering surface induced by this mode. At second order, a gradient mode generated in Single-field inflation is shown to induce a quadrupole moment. For instance in a matter-dominated model it is equal to 5/18 times the square of the linear gradient part. This quadrupole can be cancelled by superposing a quadratic perturbation. The result is shown to be a non-linear extension of Weinberg's adiabatic modes: a long-wavelength physical mode which looks locally like a coordinate transformation.

  17. Pressure Gradient Evolution and Substorm Onset

    Science.gov (United States)

    Zhonghua, Y.; Pu, Z.; Cao, X.; Nishimura, T.; Zhang, H.; Fu, S.; Xie, L.; Guo, R.

    2011-12-01

    Near-Earth current disruption (NECD) and substorm current wedge (SCW) formation are two related key phenomena for substorm onset. They are believed to be in close association with evolution of pressure gradient near the inner edge of plasma sheet. In the past, a few attempts have been made to investigate the pressure gradient in the late growth phase based on one- or two-spacecraft observations (e.g. , Korth et al., 1991; Pu et al., 1992; Shiokawa et al., 1998; Xing et al., 2010, 2011,etc). In this paper, with linearization assumption in the inner-probe region, we use THEMIS three-probe measurements to estimate the pressure gradient near the inner edge of the equatorward and duskward (dawnward) plasma sheet where pressure gradient in the Z-direction is almost vanished. We therefore can roughly get the two-dimensional pressure gradient in the X- and Y-direction simultaneously. Our observations indicate that the pressure gradients in both the X- and Y-direction enhance right after (within one minute) substorm onset. The enhanced pressure gradient in the Y-direction is duskward (dawnward) when the probes are in the duskside (dawnside) of the enhanced earthward flow in the growth phase. The enhanced dawn-dusk pressure gradients can drive downward field-aligned current (FAC) on the dawnside and upward FAC on the duskside, thus make contributions to the NECD and formation of SCW. THEMIS in situ data and all-sky auroral images for two events are presented, followed by a brief discussion.

  18. Thermal gradient analysis of solidifying casting

    Directory of Open Access Journals (Sweden)

    J. Suchoń

    2008-08-01

    Full Text Available For description of casting solidification and crystallization process the thermal derivative analysis (TDA is commonly used. Besides the process kinetics considered in TDA method to describe the solidification process, the thermal gradient analysis can be also used for this purpose [1, 2]. In conducted studies analysis of thermal gradient distribution inside the solidifying wedge casting was shown which enabled determination of heat flow intensity on casting section.

  19. The local power of the gradient test

    CERN Document Server

    Lemonte, Artur

    2010-01-01

    The asymptotic expansion of the distribution of the gradient test statistic is derived for a composite hypothesis under a sequence of Pitman alternative hypotheses converging to the null hypothesis at rate $n^{-1/2}$, $n$ being the sample size. Comparisons of the local powers of the gradient, likelihood ratio, Wald and score tests reveal no uniform superiority property. The power performance of all four criteria in one-parameter exponential family is examined.

  20. NEW STRAIN GRADIENT THEORY AND ANALYSIS

    Institute of Scientific and Technical Information of China (English)

    Dake Yi; Tzu Chiang Wang; Shaohua Chen

    2009-01-01

    A new strain gradient theory which is based on energy nonlocal model is proposed in this paper, and the theory is applied to investigate the size effects in thin metallic wire torsion, ultra-thin beam bending and micro-indentation of polycrystalline copper. First, an energy nonlocal model is suggested. Second, based on the model, a new strain gradient theory is derived. Third, the new theory is applied to analyze three representative experiments.

  1. The gradient flow in a twisted box

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, Alberto [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC

    2013-08-15

    We study the perturbative behavior of the gradient flow in a twisted box. We apply this information to define a running coupling using the energy density of the flow field. We study the step-scaling function and the size of cutoff effects in SU(2) pure gauge theory. We conclude that the twisted gradient flow running coupling scheme is a valid strategy for step-scaling purposes due to the relatively mild cutoff effects and high precision.

  2. Comparation sensory characteristic, non-volatile compounds, volatile compounds and antioxidant activity of MRPs by novel gradient temperature-elevating and traditional isothermal methods

    National Research Council Canada - National Science Library

    Huang, Meigui; Zhang, Xiaoming; Karangwa, Eric

    2015-01-01

    .... The main purpose of the present study was to compare the color, taste characteristic, non-volatile compounds, volatile compounds and antioxidant activity of MRPs prepared by the novel gradient...

  3. A novel method to load topotecan into liposomes driven by a transmembrane NH₄EDTA gradient.

    Science.gov (United States)

    Yang, Yuehui; Ma, Yanling; Wang, Shaoning

    2012-02-01

    Antitumor drugs not only cause cytocidal effect on cancer cells, but also damage on normal healthy tissues, resulting in side effects. Liposome encapsulation can result in reduced systematic distribution due to the enhanced permeability and retention (EPR) effect, accompanied by drug accumulation in liver, spleen, and other immune organs, which can cause damage to those organs. It has been demonstrated that EDTA, frequently used as a chelator, possesses a synergistic antitumor effect. Indeed, our previous study showed that EDTA could reduce the toxicity of anthracyclines to the heart and immune organs. In this study, we intended to encapsulate topotecan within liposome adopting transmembrane NH(4)EDTA gradient in order to increase the antitumor activity and decrease the toxicity against normal immune organs. Regarding the encapsulation efficiency of topotecan liposomes, both the pH value of the buffer and the cholesterol content showed significant effects on encapsulation and drug retention. Liposome encapsulation dramatically increased the antitumor activity of topotecan compared to free drug (pgradient or a (NH(4))(2)SO(4) gradient (tumor inhibition ratios were 85.6% and 84.1%, respectively). However, a significant decrease in toxicity against the immune organs was found in liposomes prepared by a NH(4)EDTA gradient compared to those prepared by a (NH(4))(2)SO(4) gradient. These results suggest the superiority of the proposed gradient for topotecan encapsulation in decreasing its toxicity on immune systems.

  4. Modified TB rapid test by proteinase K for rapid diagnosis of pleural tuberculosis.

    Science.gov (United States)

    Yari, Shamsi; Hadizadeh Tasbiti, Alireza; Ghanei, Mostafa; Shokrgozar, Mohammad Ali; Fateh, Abolfazl; Yari, Fatemeh; Bahrmand, Ahmadreza

    2016-03-01

    The diagnosis of pleural tuberculosis continues to be a challenge due to the low sensitivity of traditional diagnostic methods. Better and more rapid tests are needed for diagnosis of pleural TB. In this study, pleural fluids were tested with rapid test to determine Mycobacterium tuberculosis (MTB antigen). Affinity chromatography was used to purify specific polyclonal antibodies against MTB antigen. Pleural samples after decontamination were treated with proteinase K. Rapid test for pleural fluids was prepared by specific antibody. Rapid test was performed on 85 pleural fluid patients. The patients had a mean age of 46.55 ± 15.96 years and 38 were men. The performance of rapid test, using proteinase K, was found to be the most impressive: sensitivity 93%, specificity 94%, PPV 90%, and NPV 96% compared with adenosine deaminase test (ADA), PCR, smear, and culture. The present study did demonstrate that modified TB rapid test can substantially improve the diagnosis of extrapulmonary TB.

  5. 数据立方梯度挖掘的研究%The Research of the Cube Gradient Mining

    Institute of Scientific and Technical Information of China (English)

    刘玉葆; 冯玉才; 王元珍; 冯剑琳

    2003-01-01

    With the rapid development of data warehouse and OLAP techniques, the researchers begin to pay atten-tion to the data mining in the data cube. Recently, Dr. T. Imielinski etc. firstly presented the problem of the cubegradient mining that is a generalization of association rule in data cube. In this paper, we firstly introduce the relatedconcepts of data cube and condensed cube with an emphasis. Then we introduce some interesting problems related tothe cube gradient mining including: constrained cube gradient mining and the query language of cube gradient. Final-ly, we introduce several issues on the combination of cube gradient and the condensed cube, that is, the cube gradientmining in the materialized data cube and the integration of cube gradient mining and cube browse.

  6. Interplay between transport barriers and density gradient

    Science.gov (United States)

    Sarazin, Y.; Grandgirard, V.; Dif-Pradalier, G.; Garbet, X.; Ghendrih, Ph.

    2006-09-01

    The present paper addresses two critical issues of zonal flows: the evidence of control parameters of their driving term, namely the Reynolds stress, and how they back-react on turbulence and transport. Kinetic nonlinear simulations are performed with the GYSELA code [V. Grandgirard et al., J. Comput. Phys. (to be published)], which models the slab branch of the ion temperature gradient driven instability in the four-dimensional drift-kinetic regime. First, the numerical results show that the gradient of the guiding center density, related to the general potential vorticity, is stabilizing both linearly, by increasing the instability threshold, and nonlinearly, by activating zonal flows. Accordingly, the Reynolds stress is found to scale like LΩ-2 in the quasilinear regime, LΩ being the gradient length of the guiding center density. Second, the local temperature gradient appears to increase linearly with the curvature of the zonal flows, regardless of its sign. Such behavior agrees qualitatively with a perturbative theory. Indeed, while linear eigenmodes are localized at the maximum of the temperature gradient in the absence of zonal flows, they tend to be expelled if both exhibit a maximum at the same location. In this case, the reduction mechanism of the turbulent transport results from the ability of large zonal flow curvatures to render strong temperature gradients stable with respect to perturbations.

  7. Gradient-based compressive image fusion

    Institute of Scientific and Technical Information of China (English)

    Yang CHEN‡; Zheng QIN

    2015-01-01

    We present a novel image fusion scheme based on gradient and scrambled block Hadamard ensemble (SBHE) sam-pling for compressive sensing imaging. First, source images are compressed by compressive sensing, to facilitate the transmission of the sensor. In the fusion phase, the image gradient is calculated to reflect the abundance of its contour information. By com-positing the gradient of each image, gradient-based weights are obtained, with which compressive sensing coefficients are achieved. Finally, inverse transformation is applied to the coefficients derived from fusion, and the fused image is obtained. Information entropy (IE), Xydeas’s and Piella’s metrics are applied as non-reference objective metrics to evaluate the fusion quality in line with different fusion schemes. In addition, different image fusion application scenarios are applied to explore the scenario adaptability of the proposed scheme. Simulation results demonstrate that the gradient-based scheme has the best per-formance, in terms of both subjective judgment and objective metrics. Furthermore, the gradient-based fusion scheme proposed in this paper can be applied in different fusion scenarios.

  8. Melanoma cells break down LPA to establish local gradients that drive chemotactic dispersal.

    Directory of Open Access Journals (Sweden)

    Andrew J Muinonen-Martin

    2014-10-01

    Full Text Available The high mortality of melanoma is caused by rapid spread of cancer cells, which occurs unusually early in tumour evolution. Unlike most solid tumours, thickness rather than cytological markers or differentiation is the best guide to metastatic potential. Multiple stimuli that drive melanoma cell migration have been described, but it is not clear which are responsible for invasion, nor if chemotactic gradients exist in real tumours. In a chamber-based assay for melanoma dispersal, we find that cells migrate efficiently away from one another, even in initially homogeneous medium. This dispersal is driven by positive chemotaxis rather than chemorepulsion or contact inhibition. The principal chemoattractant, unexpectedly active across all tumour stages, is the lipid agonist lysophosphatidic acid (LPA acting through the LPA receptor LPAR1. LPA induces chemotaxis of remarkable accuracy, and is both necessary and sufficient for chemotaxis and invasion in 2-D and 3-D assays. Growth factors, often described as tumour attractants, cause negligible chemotaxis themselves, but potentiate chemotaxis to LPA. Cells rapidly break down LPA present at substantial levels in culture medium and normal skin to generate outward-facing gradients. We measure LPA gradients across the margins of melanomas in vivo, confirming the physiological importance of our results. We conclude that LPA chemotaxis provides a strong drive for melanoma cells to invade outwards. Cells create their own gradients by acting as a sink, breaking down locally present LPA, and thus forming a gradient that is low in the tumour and high in the surrounding areas. The key step is not acquisition of sensitivity to the chemoattractant, but rather the tumour growing to break down enough LPA to form a gradient. Thus the stimulus that drives cell dispersal is not the presence of LPA itself, but the self-generated, outward-directed gradient.

  9. Superparamagnetic cation-exchange adsorbents for bioproduct recovery from crude process liquors by high-gradient magnetic fishing

    DEFF Research Database (Denmark)

    Heebøll-Nielsen, Anders; Justesen, S.F.L; Hobley, Timothy John;

    2004-01-01

    Different routes were screened for the preparation of superparamagnetic cation-exchange adsorbents for the capture of proteins using high-gradient magnetic fishing. Starting from a polyglutaraldehyde-coated base particle, the most successful of these involved attachment of sulphite to oligomers...... from sweet bovine whey. Subsequently, a high-gradient magnetic fishing process was constructed for the fractionation of whey, in which lactoperoxidase was purified 36-fold and concentrated 4.7-fold...

  10. Semiautomated pH gradient ion-exchange chromatography of monoclonal antibody charge variants.

    Science.gov (United States)

    Talebi, Mohammad; Shellie, Robert A; Hilder, Emily F; Lacher, Nathan A; Haddad, Paul R

    2014-10-07

    A new approach using a chromatography system equipped with isocratic pumps and an electrolytic eluent generator (EG) is introduced, replacing external pH gradient delivery using conventional gradient systems, in which bottled buffers with preadjusted pH are mixed using a gradient pump. The EG is capable of generating high purity base or acid required for online preparation of the buffer at the point of use, utilizing deionized water as the only carrier stream. Typically, the buffer was generated from online titration of a reagent composed of low molecular weight amines. The reagent was delivered isocratically into a static mixing tee, where it was titrated to the required pH with electrolytically generated base or acid. The required pH gradient was thus conveniently generated by electrically controlling the concentration of titrant. Also, since the pH was adjusted at the point of use, this approach offered enhanced throughput in terms of eluent preparation time and labor, and with a more reproducible pH profile. The performance of the system was demonstrated by running pH gradients ranging from pH 8.2 to 10.9 on a polymer monolith cation-exchange column for high throughput profiling of charge heterogeneity of intact, basic therapeutic monoclonal antibodies. A high degree of flexibility in modulating the key parameters of the pH gradient, including the buffer concentration, the pH gradient slope and the operating pH range was demonstrated. This enabled fine-tuning of the separation conditions for each individual antibody in order to enhance the chromatographic resolution.

  11. The application of EDTA in drug delivery systems: doxorubicin liposomes loaded via NH4EDTA gradient

    Directory of Open Access Journals (Sweden)

    Song YZ

    2014-08-01

    Full Text Available Yanzhi Song,1 Zhenjun Huang,1 Yang Song,2 Qingjing Tian,1 Xinrong Liu,1 Zhennan She,1 Jiao Jiao,1 Eliza Lu,3 Yihui Deng11College of Pharmacy, Shenyang Pharmaceutical University, Shenyang, People’s Republic of China; 2Jiangsu Hansoh Pharmaceutical Co., Ltd., Lianyungang, People’s Republic of China; 3Livzon Mabpharm Inc., Zhuhai, People’s Republic of ChinaAbstract: The applications of ethylenediaminetetraacetic acid (EDTA have been expanded from the treatment of heavy metal poisoning to chelation therapies for atherosclerosis, heart disease, and cancers, in which EDTA reduces morbidity and mortality by chelating toxic metal ions. In this study, EDTA was used in a drug delivery system by adopting an NH4EDTA gradient method to load doxorubicin into liposomes with the goal of increasing therapeutic effects and decreasing drug-related cytotoxicity. The particle size of the optimum NH4EDTA gradient liposomes was 79.4±1.87 nm, and the entrapment efficiency was 95.54%±0.59%. In vitro studies revealed that liposomes prepared using an NH4EDTA gradient possessed long-term stability and delayed drug release. The in vivo studies also showed the superiority of the new doxorubicin formulation. Compared with an equivalent drug dose (5 mg/kg prepared by (NH42SO4 gradient, NH4EDTA gradient liposomes showed no significant differences in tumor inhibition ratio, but cardiotoxicity and liposome-related immune organ damage were lower, and no drug-related deaths were observed. These results show that use of the NH4EDTA gradient method to load doxorubicin into liposomes could significantly reduce drug toxicity without influencing antitumor activity.Keywords: NH4EDTA, liposome, doxorubicin, ion gradient, antitumor activity, toxicity

  12. Membrane growth can generate a transmembrane pH gradient in fatty acid vesicles.

    Science.gov (United States)

    Chen, Irene A; Szostak, Jack W

    2004-05-25

    Electrochemical proton gradients are the basis of energy transduction in modern cells, and may have played important roles in even the earliest cell-like structures. We have investigated the conditions under which pH gradients are maintained across the membranes of fatty acid vesicles, a model of early cell membranes. We show that pH gradients across such membranes decay rapidly in the presence of alkali-metal cations, but can be maintained in the absence of permeable cations. Under such conditions, when fatty acid vesicles grow through the incorporation of additional fatty acid, a transmembrane pH gradient is spontaneously generated. The formation of this pH gradient captures some of the energy released during membrane growth, but also opposes and limits further membrane area increase. The coupling of membrane growth to energy storage could have provided a growth advantage to early cells, once the membrane composition had evolved to allow the maintenance of stable pH gradients.

  13. Phytoplankton Diversity Effects on Community Biomass and Stability along Nutrient Gradients in a Eutrophic Lake.

    Science.gov (United States)

    Tian, Wang; Zhang, Huayong; Zhao, Lei; Zhang, Feifan; Huang, Hai

    2017-01-20

    The relationship between biodiversity and ecosystem functioning is a central issue in ecology, but how this relationship is affected by nutrient stress is still unknown. In this study, we analyzed the phytoplankton diversity effects on community biomass and stability along nutrient gradients in an artificial eutrophic lake. Four nutrient gradients, varying from slightly eutrophic to highly eutrophic states, were designed by adjusting the amount of polluted water that flowed into the lake. Mean phytoplankton biomass, species richness, and Shannon diversity index all showed significant differences among the four nutrient gradients. Phytoplankton community biomass was correlated with diversity (both species richness and Shannon diversity index), varying from positive to negative along the nutrient gradients. The influence of phytoplankton species richness on resource use efficiency (RUE) also changed from positive to negative along the nutrient gradients. However, the influence of phytoplankton Shannon diversity on RUE was not significant. Both phytoplankton species richness and Shannon diversity had a negative influence on community turnover (measured as community dissimilarity), i.e., a positive diversity-stability relationship. Furthermore, phytoplankton spatial stability decreased along the nutrient gradients in the lake. With increasing nutrient concentrations, the variability (standard deviation) of phytoplankton community biomass increased more rapidly than the average total biomass. Results in this study will be helpful in understanding the phytoplankton diversity effects on ecosystem functioning and how these effects are influenced by nutrient conditions in aquatic ecosystems.

  14. Phytoplankton Diversity Effects on Community Biomass and Stability along Nutrient Gradients in a Eutrophic Lake

    Science.gov (United States)

    Tian, Wang; Zhang, Huayong; Zhao, Lei; Zhang, Feifan; Huang, Hai

    2017-01-01

    The relationship between biodiversity and ecosystem functioning is a central issue in ecology, but how this relationship is affected by nutrient stress is still unknown. In this study, we analyzed the phytoplankton diversity effects on community biomass and stability along nutrient gradients in an artificial eutrophic lake. Four nutrient gradients, varying from slightly eutrophic to highly eutrophic states, were designed by adjusting the amount of polluted water that flowed into the lake. Mean phytoplankton biomass, species richness, and Shannon diversity index all showed significant differences among the four nutrient gradients. Phytoplankton community biomass was correlated with diversity (both species richness and Shannon diversity index), varying from positive to negative along the nutrient gradients. The influence of phytoplankton species richness on resource use efficiency (RUE) also changed from positive to negative along the nutrient gradients. However, the influence of phytoplankton Shannon diversity on RUE was not significant. Both phytoplankton species richness and Shannon diversity had a negative influence on community turnover (measured as community dissimilarity), i.e., a positive diversity–stability relationship. Furthermore, phytoplankton spatial stability decreased along the nutrient gradients in the lake. With increasing nutrient concentrations, the variability (standard deviation) of phytoplankton community biomass increased more rapidly than the average total biomass. Results in this study will be helpful in understanding the phytoplankton diversity effects on ecosystem functioning and how these effects are influenced by nutrient conditions in aquatic ecosystems. PMID:28117684

  15. The Effect of Pallet Component Geometry on Temperature Gradient During Cooling

    Directory of Open Access Journals (Sweden)

    Bajwoluk A.

    2015-03-01

    Full Text Available The paper discusses the impact of the geometry of foundry pallet components on the value of temperature gradient on the wall crosssection during heat treatment. The gradient is one of the most important factors determining the distribution of thermal stresses in these items. Analysis of quantitative simulation was carried out to detect possible effect of the type of connection between pallet walls and thickness of these walls (ribs on the interior temperature distribution during rapid cooling. The analysis was performed for five basic designs of wall connections used in pallets. Basing on the results obtained, the conclusions were drawn on the best connection between the ribs in foundry pallets.

  16. Ordered Micro/Nanostructures with Geometric Gradient: From Integrated Wettability "Library" to Anisotropic Wetting Surface.

    Science.gov (United States)

    Xue, Peihong; Nan, Jingjie; Wang, Tieqiang; Wang, Shuli; Ye, Shunsheng; Zhang, Junhu; Cui, Zhanchen; Yang, Bai

    2017-01-01

    Geometric gradients within ordered micro/nanostructures exhibit unique wetting properties. Well-defined and ordered microsphere arrays with geometric gradient (OMAGG) are successfully fabricated through combining colloidal lithography and inclined reactive ion etching (RIE). During the inclined RIE, the graded etching rates in vertical direction of etcher chamber are the key to generating a geometric gradient. The OMAGG can be used as an effective mask for the preparation of micro/nanostructure arrays with geometric gradient by selective RIE. Through this strategy, a well-defined wettability "library" with graded silicon cone arrays is fabricated, and the possibility of screening one desired "book" from the designated wettability "library" is demonstrated. Meanwhile, the silicon cone arrays with geometric gradient (SCAGG) can be applied to control the wetting behavior of water after being modified by hydrophilic or hydrophobic chemical groups. Based on this result, a temperature-responsive wetting substrate is fabricated by modifying poly n-isopropyl acrylamide (PNIPAM) on the SCAGG. These wettability gradients have great potential in tissue engineering, microfluidic devices, and integrated sensors. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Irreducible decomposition of strain gradient tensor in isotropic strain gradient elasticity

    CERN Document Server

    Lazar, Markus

    2016-01-01

    In isotropic strain gradient elasticity, we decompose the strain gradient tensor into its irreducible pieces under the n-dimensional orthogonal group O(n). Using the Young tableau method for traceless tensors, four irreducible pieces (n>2), which are canonical, are obtained. In three dimensions, the strain gradient tensor can be decomposed into four irreducible pieces with 7+5+3+3 independent components whereas in two dimensions, the strain gradient tensor can be decomposed into three irreducible pieces with 2+2+2 independent components. The knowledge of these irreducible pieces is extremely useful when setting up constitutive relations and strain energy.

  18. Improving the accuracy of pulsed field gradient NMR diffusion experiments: Correction for gradient non-uniformity

    Science.gov (United States)

    Connell, Mark A.; Bowyer, Paul J.; Adam Bone, P.; Davis, Adrian L.; Swanson, Alistair G.; Nilsson, Mathias; Morris, Gareth A.

    2009-05-01

    Pulsed field gradient NMR is a well-established technique for the determination of self-diffusion coefficients. However, a significant source of systematic error exists in the spatial variation of the applied pulsed field gradient. Non-uniform pulsed field gradients cause the decay of peak amplitudes to deviate from the expected exponential dependence on gradient squared. This has two undesirable effects: the apparent diffusion coefficient will deviate from the true value to an extent determined by the choice of experimental parameters, and the error estimated by the nonlinear least squares fitting will contain a significant systematic contribution. In particular, the apparent diffusion coefficient determined by exponential fitting of the diffusional attenuation of NMR signals will depend both on the exact pulse widths used and on the range of gradient amplitudes chosen. These problems can be partially compensated for if experimental attenuation data are fitted to a function corrected for the measured spatial dependence of the gradient and signal strength. This study describes a general alternative to existing methods for the calibration of NMR diffusion measurements. The dominant longitudinal variation of the pulsed field gradient amplitude and the signal strength are mapped by measuring pulsed field gradient echoes in the presence of a weak read gradient. These data are then used to construct a predicted signal decay function for the whole sample, which is parameterised as the exponential of a power series. Results are presented which compare diffusion coefficients obtained using the new calibration method with previous literature values.

  19. Arrays of quasi-hexagonally ordered silica nanopillars with independently controlled areal density, diameter and height gradients

    Science.gov (United States)

    Özdemir, Burcin; Huang, Wenting; Plettl, Alfred; Ziemann, Paul

    2015-03-01

    A consecutive fabrication approach of independently tailored gradients of the topographical parameters distance, diameter and height in arrays of well-ordered nanopillars on smooth SiO2-Si-wafers is presented. For this purpose, previously reported preparation techniques are further developed and combined. First, self-assembly of Au-salt loaded micelles by dip-coating with computer-controlled pulling-out velocities and subsequent hydrogen plasma treatment produce quasi-hexagonally ordered, 2-dimensional arrays of Au nanoparticles (NPs) with unidirectional variations of the interparticle distances along the pulling direction between 50-120 nm. Second, the distance (or areal density) gradient profile received in this way is superimposed with a diameter-controlled gradient profile of the NPs applying a selective photochemical growth technique. For demonstration, a 1D shutter is used for locally defined UV exposure times to prepare Au NP size gradients varying between 12 and 30 nm. Third, these double-gradient NP arrangements serve as etching masks in a following reactive ion etching step delivering arrays of nanopillars. For height gradient generation, the etching time is locally controlled by applying a shutter made from Si wafer piece. Due to the high flexibility of the etching process, the preparation route works on various materials such as cover slips, silicon, silicon oxide, silicon nitride and silicon carbide.

  20. Electrochemical Deposition of Ni-W Gradient Deposit and Its Structural Characterization

    Institute of Scientific and Technical Information of China (English)

    王宏智; 姚素薇; 张卫国

    2003-01-01

    The Ni-W gradient deposit with nano-structure was prepared by an electrochemical deposition method.X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDXA) indicate that the crystallite size of the deposit decreases from 10.3nm to 1.5nm and the crystal grating aberrance increases with the increase of W content in the growing direction of the deposit. The structure of deposit changes from crystalline to amorphous stepwise with associated increase of crystal grating aberrance, and presents gradient distribution. These show that the deposit isgradient with nano-structure.

  1. Evaluation of centrifugation parameters for density gradient experiments by means of a programmable pocket calculator.

    Science.gov (United States)

    Kreutzfeldt, C

    1980-10-01

    A calculation program is proposed suitable for programmable pocket calculators (e.g. HP series) to estimate s20,w f omega2 dt values from density gradient centrifugation data. The program can be applied to linear or exponential density gradients prepared from sucrose or glycerol solutions spun in zonal rotors or swinging bucket rotors. A wide solute concentration range and temperature range is accounted for. Constants for empirical density calculation of glycerol and sucrose solutions concentrated in % (w/v) are estimated. Experimental verification of the program was carried out.

  2. Rapid Prototyping Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The ARDEC Rapid Prototyping (RP) Laboratory was established in December 1992 to provide low cost RP capabilities to the ARDEC engineering community. The Stratasys,...

  3. [Methods for the rapid preparation of paraffin blocks].

    Science.gov (United States)

    Shmurun, R I

    1992-01-01

    Two accelerated chloroform-paraffin processings of materials with the use of ultrasound (US) and microwave (MW) irradiation in the stove "Electronica" as well as a combined method with US- and MW-irradiation are proposed to shorten drastically the duration of the prehistologic processing.

  4. A simple and rapid nucleic acid preparation method for reverse ...

    African Journals Online (AJOL)

    USER

    2010-03-29

    Mar 29, 2010 ... detergent (0.5% Triton XL-80 N) buffers, vortexed for 3 min and then 2.5 µl of this aliquots was used in. RT-PCR. ... 2003). However, successful application of these methods .... used non-ionic detergents, and have involved a multitude .... potato S carlavirus (PVS) revealed by analysis of RT-PCR-amplified.

  5. 原位制备纳米功能化金电极快速检测牛奶中的微生物%Rapid Detection of Microorganisms in Milk Using an In-situ Prepared Nano-functionalized Gold Electrode

    Institute of Scientific and Technical Information of China (English)

    汪学英; 顾锋; 尹凡; 屠一锋

    2012-01-01

    An in-situ, facile and rapid method was developed to prepare a nano-functionalized gold electrode. By the electrolysis under applied potential of +2 V in PBS of pH 7. 0 for 10 min, a rough nano-porous film formed on the surface of a polished gold plate electrode. This novel nano-functionalized gold electrode could be applied for rapid detection of bacteria quantity in milk. The detection was based on the catalysis of lipid peroxidation on cell membrane of bacteria by the nano-porous Au film. The response of the current in chronoamperometry would linearly respond the bacterial content in milk which was calibrated by the national standard method (Standard plate count method). Therefore the accurate quantity of bacteria was attained from the current response on prepared electrode. The results showed that the target bacteria could be detected at a content range from 1. 1×103 cfu/mL to 2. 5×107 cfu/mL. The whole process of the detection could be completed within 1 h.%在0.1 mol/L磷酸盐缓冲溶液(PBS,pH 7.0)中,于2.0V恒电位电解10 min,即可在金电极表面原位、快速制备纳米功能化修饰膜.经原子力显微镜表征,此修饰膜具有纳米尺度的蓬松结构.此纳米金膜对细胞膜上脂质过氧化反应具有显著的催化作用,因而对细菌产生电流响应.采用传统的标准平板计数法对试样进行细菌培养计数作为校正,以计时电流法电流响应作为输出信号进行细菌的测定,响应电流和细菌数量呈线性关系,据此可对牛奶样品中细菌浓度进行快速测定.本方法的测定范围为1.1×103~2.5×107 cfu/mL,检测时间缩短至1h以内,较平板计数法有显著改善.

  6. Poly(lactic-co-glycolic acid)/tricalcium phosphate scaffolds prepared by rapid prototyping technology for the repair of radial defects in rabbits%快速成型聚乳酸-聚羟乙酸/磷酸三钙支架修复兔桡骨缺损

    Institute of Scientific and Technical Information of China (English)

    孙梁; 熊卓

    2011-01-01

    背景:理想的骨修复材料除必须具有生物相容性、可吸收性、利于血管化及迅速被新生组织替代的孔隙率,还需要有与骨组织相似三维结构.目的:检验快速成型工艺制作的聚乳酸-聚羟乙酸/磷酸三钙支架复合骨形态发生蛋白修复兔桡骨缺损的效果.方法:将乳酸乙醇酸共聚物溶于1,4-二氧六环中并混合粉末状磷酸三钙制备成液态的浆料,放入生物材料快速成形机TissFormTM制备出直径5 mm,长15 mm的圆柱形人工骨载体材料.按每个材料15 mg的标准,采用预湿、负压复合骨形态发生蛋白、冻干3步处理,制备出活性人工骨材料.健康新西兰大白兔20只,制备右前肢桡骨中上段15 mm骨缺损模型,实验组和对照组分别植入复合骨形态发生蛋白的活性人工骨和未复合骨形态发生蛋白的单纯支架.通过影像学、组织学、材料降解及骨密度评价修复兔桡骨缺损的效果.结果与结论:12周时实验组骨缺损愈合,新生骨痂连接缺损断端并塑形,支架材料近于完全降解,各检测指标与对照组比较差异均有显著性意义,对照组骨缺损内未见新骨形成.结果表明复合骨形态发生蛋白的聚乳酸-聚羟乙酸/磷酸三钙支架可以很好的修复兔15 mm骨缺损,且降解速度与成骨速度匹配良好.%BACKGROUND:The ideal bone repair materials must be biocompatible and absorbable, have the porosity that is conducive to the vascularization and rapidly replaced by new tissue, as well as a three-dimensional structu re similar to bone tissue.OBJECTIVE:To test the effect of poly(lactic-co-glycolic acid )/tricalcium phosphate (PLGA/TCP) scaffolds prepared by rapid prototyping technology loaded with bone morphogenetic protein in the repair of radial defect in rabbits.METHODS:The lactic acid/glycolic acid copolymer dissolved in 1,4-dioxane and mixed with calcium phosphate powder to prepare a liquid slurry, then placing into a biomaterial rapid

  7. How Prepared is Prepared Enough?

    Science.gov (United States)

    Porter-Levy; Macleod; Rickert

    1996-10-01

    A 17-year-old female was in the final stage in treatment of right unilateral cleft lip and palate. She had undergone a number of previous surgeries. Hearing and speech were good on evaluation, and her social and family situation were deemed excellent. After preparatory orthodontics she underwent a Lefort I maxillary advancement. Surgery was successful and she was admitted into postoperative recovery. However, the lack of adequate preoperative preparation caused traumatic reaction from the patient and her parents: anxiety over appearance, crying, refusal of oral fluids and oral care, refusal of analgesia, and refusal to mobilize. The patience and persistence of hospital staff slowly overcame all adversities and the patient moved on to full and successful recovery, but this case prompted changes in preoperative procedures and involvement of patients and their families in postoperative meal selection, planing, and preparation.

  8. Low temperature rapid preparation of nano-selenium with water bath in the presence of sodium alginate as soft template & characterization%海藻酸钠模板法低温水浴制备纳米硒与表征

    Institute of Scientific and Technical Information of China (English)

    吴永军; 倪永红

    2012-01-01

    Food-grade sodium alginate was used as soft template to preparate different morphologies of nanoselenium rapidly by the redaction of NH2OH·HCl and H2SeO3 in water bath at low temperature.Some important factors which influencing the generation and morphology of products had been studied and discussed o Such as: the amounts of soft template, the reaction temperature and the reaction time.The structure of product was characterized by SEM, XRD.The results showed that external causes had a potent effect on the morphology of nano-selenium.The Selenium nanowires prepared under the optimal reaction condition are uniform and well- dispersed,with the. average diameter was approximately 20-30nm, length was up to several micron, lengthdiameter ratio was more than 50.%以食品级海藻酸钠为软模板,在水浴中用盐酸羟胺还原亚硒酸低温快速制备纳米硒。探讨了模板用量、反应温度、反应时间对纳米硒生长和产物形貌的影响,并借以扫描电子显微镜、X射线衍射对产物进行了表征。结果表明,外因极大影响着纳米硒的形貌,最优反应条件下制备出的纳米硒线形貌均匀、分散性好,平均直径20~30nm,长度可达数微米,长径比大于50。

  9. Ceramic microfabrication by rapid prototyping process chains

    Indian Academy of Sciences (India)

    R Knitter; W Bauer

    2003-02-01

    Fabrication of micropatterned ceramics or ceramic microparts make high demands on the precision and resolution of the moulding process. As finishing of miniaturised or micropatterned ceramic components is nearly impossible, shaping has to be done by a replication step in the green, unfired state. To avoid high tooling costs in product development, a rapid prototyping process chain has been established that enables rapid manufacturing of ceramic microcomponents from functional models to small lot series within a short time. This process chain combines the fast and inexpensive supply of master models by rapid prototyping with accurate and flexible ceramic manufacturing by low-pressure injection moulding. Besides proper feedstock preparation and sufficient small grain size, the quality of the final components is mainly influenced by the quality of the master model. Hence, the rapid prototyping method must be carefully selected to meet the requirements of the component to be fabricated.

  10. Constrained length minimum inductance gradient coil design.

    Science.gov (United States)

    Chronik, B A; Rutt, B K

    1998-02-01

    A gradient coil design algorithm capable of controlling the position of the homogeneous region of interest (ROI) with respect to the current-carrying wires is required for many advanced imaging and spectroscopy applications. A modified minimum inductance target field method that allows the placement of a set of constraints on the final current density is presented. This constrained current minimum inductance method is derived in the context of previous target field methods. Complete details are shown and all equations required for implementation of the algorithm are given. The method has been implemented on computer and applied to the design of both a 1:1 aspect ratio (length:diameter) central ROI and a 2:1 aspect ratio edge ROI gradient coil. The 1:1 design demonstrates that a general analytic method can be used to easily obtain very short gradient coil designs for use with specialized magnet systems. The edge gradient design demonstrates that designs that allow imaging of the neck region with a head sized gradient coil can be obtained, as well as other applications requiring edge-of-cylinder regions of uniformity.

  11. On fracture in finite strain gradient plasticity

    DEFF Research Database (Denmark)

    Martínez Pañeda, Emilio; Niordson, Christian Frithiof

    2016-01-01

    In this work a general framework for damage and fracture assessment including the effect of strain gradients is provided. Both mechanism-based and phenomenological strain gradient plasticity (SGP) theories are implemented numerically using finite deformation theory and crack tip fields are invest......In this work a general framework for damage and fracture assessment including the effect of strain gradients is provided. Both mechanism-based and phenomenological strain gradient plasticity (SGP) theories are implemented numerically using finite deformation theory and crack tip fields...... are investigated. Differences and similarities between the two approaches within continuum SGP modeling are highlighted and discussed. Local strain hardening promoted by geometrically necessary dislocations (GNDs) in the vicinity of the crack leads to much higher stresses, relative to classical plasticity...... predictions. These differences increase significantly when large strains are taken into account, as a consequence of the contribution of strain gradients to the work hardening of the material. The magnitude of stress elevation at the crack tip and the distance ahead of the crack where GNDs significantly alter...

  12. Polarization Gradient Cooling by Zeeman-Effect-Assisted Saturated Absorption

    Institute of Scientific and Technical Information of China (English)

    HAN Shun-Li; CHENG Bing; ZHANG Jiag-Fang; XU Yun-Fei; WANG Zhao-Ying; LIN Qiang

    2009-01-01

    A novel and simple method to realize polarization gradient cooling(PGC)is reported.The stabilizing,shifting and rapid tuning of the frequency of the external cavity diode laser is realized by using the Zeeman-effect-assisted Doppler-free saturated absorption technique.Based on this convenient technique,~(87)Rb cold atoms are captured from room-temperature background vapor in the magneto-optical trap(MOT).Meanwhile,the steady-state number,the density and the lifetime of atoms in the MOT are measured.Subsequently,a frequency-fast-varying circuit is designed to realize PGC,which is demonstrated effectively and reliably in experiments.The temperature of the cold atom cloud is measured by two different methods,which coincide with each other.

  13. Charged particle beam scanning using deformed high gradient insulator

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yu -Jiuan

    2015-10-06

    Devices and methods are provided to allow rapid deflection of a charged particle beam. The disclosed devices can, for example, be used as part of a hadron therapy system to allow scanning of a target area within a patient's body. The disclosed charged particle beam deflectors include a dielectric wall accelerator (DWA) with a hollow center and a dielectric wall that is substantially parallel to a z-axis that runs through the hollow center. The dielectric wall includes one or more deformed high gradient insulators (HGIs) that are configured to produce an electric field with an component in a direction perpendicular to the z-axis. A control component is also provided to establish the electric field component in the direction perpendicular to the z-axis and to control deflection of a charged particle beam in the direction perpendicular to the z-axis as the charged particle beam travels through the hollow center of the DWA.

  14. Fabrication of CTP/HAp novel gradient composite bioceramics

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Calcium-titanium-phosphate(CaTi4(PO4)6, CTP)/hydroxyapatite(HAp) is a kind of novel gradient composite bioceramics,which has excellent biocompatibility and bioactivity. CTP ceramic film was synthesized one-step on the surface of titanium using micro-arc oxidation(MAO). The CTP/HAp composite bioceramics were prepared by soaking CTP film in HAp inducing solution for several days. XRD, SEM and EDX were used to characterize the bio-ceramic films phase and composition, morphology and component. The influence of electrolyte molar ratio of Ca to P and the current density to the synthesis of film was studied, and the optimized value of parameters above were 1/6 and 15A/dm2. The parameters of HAp inducing solution, such as component and pH value were also studied and the best pH value which is adjusted by NaOH is 6.4.

  15. Comparison of the conditioning of High Gradient Accelerating Structures

    CERN Document Server

    Degiovanni, Alberto; Giner Navarro, Jorge

    2016-01-01

    Accelerating gradients in excess of 100 MV/m, at very low breakdown rates, have been successfully achieved in numerous CLIC prototype accelerating structures. The conditioning and operational histories of several structures, tested at KEK and CERN, have been compared and there is clear evidence that the conditioning progresses with the number of RF pulses and not the number of breakdowns. This observation opens the possibility that the optimum conditioning strategy, which minimizes the total number of breakdowns the structure is subject to without increasing conditioning time, may be to never exceed the breakdown rate target for operation. The result is also likely to have a strong impact on efforts to understand the physical mechanism underlying conditioning and may lead to preparation procedures which reduce conditioning time.

  16. Evidence of counter-gradient growth in western pond turtles (Actinemys marmorata) across thermal gradients

    Science.gov (United States)

    Snover, Melissa; Adams, Michael J.; Ashton, Donald T.; Bettaso, Jamie B.; Welsh, Hartwell H.

    2015-01-01

    Counter-gradient growth, where growth per unit temperature increases as temperature decreases, can reduce the variation in ectothermic growth rates across environmental gradients. Understanding how ectothermic species respond to changing temperatures is essential to their conservation and management due to human-altered habitats and changing climates.

  17. Collective chemotaxis through noisy multicellular gradient sensing

    CERN Document Server

    Varennes, Julien; Mugler, Andrew

    2016-01-01

    Collective cell migration in response to a chemical cue occurs in many biological processes such as morphogenesis and cancer metastasis. Clusters of migratory cells in these systems are capable of responding to gradients of less than 1% difference in chemical concentration across a cell length. Multicellular systems are extremely sensitive to their environment and while the limits to multicellular sensing are becoming known, how this information leads to coherent migration remains poorly understood. We develop a computational model of multicellular sensing and migration in which groups of cells collectively measure noisy chemical gradients. The output of the sensing process is coupled to individual cells polarization to model migratory behavior. Through the use of numerical simulations, we find that larger clusters of cells detect the gradient direction with higher precision and thus achieve stronger polarization bias, but larger clusters also induce more drag on collective motion. The trade-off between these...

  18. Time Rate Gradient Effects and Negative Mass

    Science.gov (United States)

    Miksch, Edmond

    2008-03-01

    The Harvard tower Experiment and tests with accurate atomic clocks show that a clock at a high elevation indicates more elapsed time than a clock at a low elevation, both clocks properly measuring time at their locations. This fact mandates that Newton's first law of motion be rewritten to cite impulse balance rather than force balance. Time rate gradient effects explain how the weight of a precisely vertical and precisely uniform electric field or a precisely vertical and precisely uniform magnetic field is supported in a precisely unidirectional gravitational field. Time rate gradient effects also explain how the weight of a unidirectional gravitational field is reacted. It is confirmed that the mass density of the gravitational field is negative. http://www.TimeRateGradient.com; http://www.Negative-Mass.com; http://www.EinsteinsElevator.com

  19. Dynamics of gradient formation by intracellular shuttling

    Energy Technology Data Exchange (ETDEWEB)

    Berezhkovskii, Alexander M. [Mathematical and Statistical Computing Laboratory, Division of Computational Bioscience, Center for Information Technology, National Institutes of Health, Bethesda, Maryland 20892 (United States); Shvartsman, Stanislav Y. [Department of Chemical and Biological Engineering and Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544 (United States)

    2015-08-21

    A number of important cellular functions rely on the formation of intracellular protein concentration gradients. Experimental studies discovered a number of mechanisms for the formation of such gradients. One of the mechanisms relies on the intracellular shuttling of a protein that interconverts between the two states with different diffusivities, under the action of two enzymes, one of which is localized to the plasma membrane, whereas the second is uniformly distributed in the cytoplasm. Recent work reported an analytical solution for the steady state gradient in this mechanism, obtained in the framework of a one-dimensional reaction-diffusion model. Here, we study the dynamics in this model and derive analytical expressions for the Laplace transforms of the time-dependent concentration profiles in terms of elementary transcendental functions. Inverting these transforms numerically, one can obtain time-dependent concentration profiles of the two forms of the protein.

  20. Conjugate gradient algorithms using multiple recursions

    Energy Technology Data Exchange (ETDEWEB)

    Barth, T.; Manteuffel, T.

    1996-12-31

    Much is already known about when a conjugate gradient method can be implemented with short recursions for the direction vectors. The work done in 1984 by Faber and Manteuffel gave necessary and sufficient conditions on the iteration matrix A, in order for a conjugate gradient method to be implemented with a single recursion of a certain form. However, this form does not take into account all possible recursions. This became evident when Jagels and Reichel used an algorithm of Gragg for unitary matrices to demonstrate that the class of matrices for which a practical conjugate gradient algorithm exists can be extended to include unitary and shifted unitary matrices. The implementation uses short double recursions for the direction vectors. This motivates the study of multiple recursion algorithms.

  1. Dynamics of gradient formation by intracellular shuttling

    Science.gov (United States)

    Berezhkovskii, Alexander M.; Shvartsman, Stanislav Y.

    2015-08-01

    A number of important cellular functions rely on the formation of intracellular protein concentration gradients. Experimental studies discovered a number of mechanisms for the formation of such gradients. One of the mechanisms relies on the intracellular shuttling of a protein that interconverts between the two states with different diffusivities, under the action of two enzymes, one of which is localized to the plasma membrane, whereas the second is uniformly distributed in the cytoplasm. Recent work reported an analytical solution for the steady state gradient in this mechanism, obtained in the framework of a one-dimensional reaction-diffusion model. Here, we study the dynamics in this model and derive analytical expressions for the Laplace transforms of the time-dependent concentration profiles in terms of elementary transcendental functions. Inverting these transforms numerically, one can obtain time-dependent concentration profiles of the two forms of the protein.

  2. Adaptive Thermostats for Noisy Gradient Systems

    CERN Document Server

    Leimkuhler, Benedict

    2015-01-01

    We study numerical methods for sampling probability measures in high dimensions where the underlying model is only approximately identified with a gradient system. Extended stochastic dynamical methods are discussed which have application to multiscale models, nonequilibrium molecular dynamics and Bayesian sampling techniques arising in emerging machine learning applications. In addition to providing a more comprehensive discussion of the foundations of these methods, we propose a new numerical method for the Adaptive Langevin/stochastic gradient Nos\\'e-Hoover thermostat that achieves a dramatic improvement in numerical efficiency over the most popular stochastic gradient methods reported in the literature. We also demonstrate that the newly-established method inherits a superconvergence property (fourth order convergence to the invariant measure for configurational quantities) recently demonstrated in the setting of Langevin dynamics. Our findings are verified by numerical experiments.

  3. Subduction zones seen by GOCE gravity gradients

    DEFF Research Database (Denmark)

    Švarc, Mario; Herceg, Matija; Cammarano, Fabio

    and used as starting point for analysis based on image processing. On obtained maps, locations of known subduction zones were represented with characteristic elongated patterns and cross-sections. Cross sections of well-known subduction zones were used as input patterns for pattern recognition method....... Few pattern recognition methods were tested on all 6 gravity gradient tensor components represented as global scale maps with resolution of 100km (corresponds to the resolution of the GOCE satellite data). By adjusting pattern recognition methods’ features and optimizing various input patterns......, the best method was applied. That is a combination of methods based on SURF (Speeded Up Robust Features) and MSER (Maximally Stable Extremal Regions) algorithms provided in MATLAB’s Computer Vision System Toolbox. Based on 6 gravity gradient components, the global gradient anomaly maps were produced...

  4. Transverse gradient in Apple-type undulators

    Science.gov (United States)

    Calvi, M.; Camenzuli, C.; Prat, E.; Schmidt, Th.

    2017-01-01

    Apple-type undulators are globally recognized as the most flexible devices for the production of variable polarized light in the soft X-ray regime, both at synchrotron and free-electron laser facilities. Recently, the implementation of transverse gradient undulators has been proposed to enhance the performance of new generation light sources. In this paper it is demonstrated that Apple undulators do not only generate linear and elliptical polarized light but also variable transverse gradient under certain conditions. A general theoretical framework is introduced to evaluate the K-value and its transverse gradient for an Apple undulator, and formulas for all regular operational modes and different Apple types (including the most recent Delta type and Apple X) are calculated and critically discussed. PMID:28452751

  5. Inversion gradients for acoustic VTI wavefield tomography

    KAUST Repository

    Li, Vladimir

    2017-03-21

    Wavefield tomography can handle complex subsurface geology better than ray-based techniques and, ultimately, provide a higher resolution. Here, we implement forward and adjoint wavefield extrapolation for VTI (transversely isotropic with a vertical symmetry axis) media using a generalized pseudospectral operator based on a separable approximation for the P-wave dispersion relation. This operator is employed to derive the gradients of the differential semblance optimization (DSO) and modified image-power objective functions. We also obtain the gradient expressions for a data-domain objective function that can more easily incorporate borehole information necessary for stable VTI velocity analysis. These gradients are similar to the ones obtained with a space-time finite-difference (FD) scheme for a system of coupled wave equations but the pseudospectral method is not hampered by the imprint of the shear-wave artifact. Numerical examples also show the potential advantages of the modified image-power objective function in estimating the anellipticity parameter η.

  6. Wavelength tuning by means of a temperature gradient in periodically poled lithium niobate

    Science.gov (United States)

    Kramb, Jason

    2005-04-01

    Nonlinear frequency conversion in periodically poled lithium niobate (PPLN) is controlled by the periodicity of the poled structure and by the crystal temperature. Crystals with multiple poled regions and crystals with a continuous periodicity change (fan-out design) can achieve rapid tuning. Changing the crystal temperature also results in tuning, however this is relatively slow for large temperature changes. Another approach, which has not yet been demonstrated, is tuning by means of a temperature gradient. This talk will show the results of such a temperature-gradient tuned PPLN device. In particular we will discuss the change in efficiency of the PPLN device and changes in the output beam profile when a temperature gradient is applied to the crystal.

  7. Solidification characterization of a new rapidly solidified Ni-Cr-Co based superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Kai, E-mail: wk-ustb@163.com [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Liu, Guoquan [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Hu, Benfu [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Li, Feng [Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ (United Kingdom); Zhang, Yiwen [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); High Temperature Materials Research Institution, CISRI, Beijing 100081 (China); Tao, Yu; Liu, Jiantao [High Temperature Materials Research Institution, CISRI, Beijing 100081 (China)

    2012-11-15

    The solidification characterization of a new rapidly solidified Ni-Cr-Co based superalloy prepared by plasma rotating electrode process was investigated by means of optical microscope, scanning electron microscope, and transmission electron microscope. The results show that the solidification microstructure changes from dendrites to cellular and microcrystal structures with decreasing powder size. The elements of Co, Cr, W and Ni are enriched in the dendrites, while Mo, Nb and Ti are higher in the interdendritic regions. The relationships between powder size with the average solid-liquid interface moving rate, the average interface temperature gradient and the average cooling rate are established. Microsegregation is increased with larger powder size. The geometric integrity of MC Prime type carbides in the powders changes from regular to diverse with decreasing powder size. The morphology and quantity of carbides depend on the thermal parameters and non-equilibrium solute partition coefficients during rapid solidification. - Highlights: Black-Right-Pointing-Pointer The relations of solidification thermal parameters with powder size are established. Black-Right-Pointing-Pointer The relation of non-equilibrium solute partition with powder size is investigated. Black-Right-Pointing-Pointer The solidification microstructure is related to thermal parameters. Black-Right-Pointing-Pointer The segregation behavior is linked to non-equilibrium partition coefficients. Black-Right-Pointing-Pointer The morphology and quantity of carbides depend on the above combined factors.

  8. On determining characteristic length scales in pressure-gradient turbulent boundary layers

    Science.gov (United States)

    Vinuesa, R.; Bobke, A.; Örlü, R.; Schlatter, P.

    2016-05-01

    In the present work, we analyze three commonly used methods to determine the edge of pressure gradient turbulent boundary layers: two based on composite profiles, the one by Chauhan et al. ["Criteria for assessing experiments in zero pressure gradient boundary layers," Fluid Dyn. Res. 41, 021404 (2009)] and the one by Nickels ["Inner scaling for wall-bounded flows subject to large pressure gradients," J. Fluid Mech. 521, 217-239 (2004)], and the other one based on the condition of vanishing mean velocity gradient. Additionally, a new method is introduced based on the diagnostic plot concept by Alfredsson et al. ["A new scaling for the streamwise turbulence intensity in wall-bounded turbulent flows and what it tells us about the `outer' peak," Phys. Fluids 23, 041702 (2011)]. The boundary layers developing over the suction and pressure sides of a NACA4412 wing section, extracted from a direct numerical simulation at chord Reynolds number Rec = 400 000, are used as the test case, besides other numerical and experimental data from favorable, zero, and adverse pressure-gradient flat-plate turbulent boundary layers. We find that all the methods produce robust results with mild or moderate pressure gradients, although the composite-profile techniques require data preparation, including initial estimations of fitting parameters and data truncation. Stronger pressure gradients (with a Rotta-Clauser pressure-gradient parameter β larger than around 7) lead to inconsistent results in all the techniques except the diagnostic plot. This method also has the advantage of providing an objective way of defining the point where the mean streamwise velocity is 99% of the edge velocity and shows consistent results in a wide range of pressure gradient conditions, as well as flow histories. Collapse of intermittency factors obtained from a wide range of pressure-gradient and Re conditions on the wing further highlights the robustness of the diagnostic plot method to determine the

  9. Critical gradient response of the Weiland model

    Science.gov (United States)

    Asp, E.; Weiland, J.; Garbet, X.; Parail, V.; Strand, P.; JET EFDA contributors, the

    2007-08-01

    The success the Weiland model has had in reproducing modulation experiments prompted this in-depth investigation into its behaviour as a critical gradient model (CGM). The critical gradient properties of the Weiland model is examined analytically and numerically and compared with the empirical CGM commonly used in experiment. A simplified Weiland CGM is derived in which the height-above-threshold dependence is not necessarily linear. Simultaneously, the validity of the empirical CGM was examined. It is shown that an effective threshold, which is higher than the instability threshold, can be obtained if pinches influence the diffusivity.

  10. Gradient Learning Algorithms for Ontology Computing

    Science.gov (United States)

    Gao, Wei; Zhu, Linli

    2014-01-01

    The gradient learning model has been raising great attention in view of its promising perspectives for applications in statistics, data dimensionality reducing, and other specific fields. In this paper, we raise a new gradient learning model for ontology similarity measuring and ontology mapping in multidividing setting. The sample error in this setting is given by virtue of the hypothesis space and the trick of ontology dividing operator. Finally, two experiments presented on plant and humanoid robotics field verify the efficiency of the new computation model for ontology similarity measure and ontology mapping applications in multidividing setting. PMID:25530752

  11. Design of spherical symmetric gradient index lenses

    Science.gov (United States)

    Miñano, Juan C.; Grabovičkić, Dejan; Benítez, Pablo; González, Juan C.; Santamaría, Asunción

    2012-10-01

    Spherical symmetric refractive index distributions also known as Gradient Index lenses such as the Maxwell-Fish-Eye (MFE), the Luneburg or the Eaton lenses have always played an important role in Optics. The recent development of the technique called Transformation Optics has renewed the interest in these gradient index lenses. For instance, Perfect Imaging within the Wave Optics framework has recently been proved using the MFE distribution. We review here the design problem of these lenses, classify them in two groups (Luneburg moveable-limits and fixed-limits type), and establish a new design techniques for each type of problem.

  12. Electric field gradients in Hg compounds

    DEFF Research Database (Denmark)

    Arcisauskaité, Vaida; Knecht, Stefan; Sauer, Stephan P. A.

    2012-01-01

    We examine the performance of Density Functional Theory (DFT) approaches based on the Zeroth-Order Regular Approximation (ZORA) Hamiltonian (with and without inclusion of spinorbit coupling) for predictions of electric ¿eld gradients (EFGs) at the heavy atom Hg nucleus. This is achieved by compar......We examine the performance of Density Functional Theory (DFT) approaches based on the Zeroth-Order Regular Approximation (ZORA) Hamiltonian (with and without inclusion of spinorbit coupling) for predictions of electric ¿eld gradients (EFGs) at the heavy atom Hg nucleus. This is achieved...

  13. Natural Gradient Approach to Multichannel Blind Deconvolution

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this paper we study the geometrical structures of FIR filters and their application to multichannel blind deconvolution.First we introduce a Lie group structure and a Riemannian structure on the manifolds of the FIR filters.Then we derive the natural gradients on the manifolds using the isometry of the Riemannian metric.Using the natural gradient,we present a novel learning algorithm for blind deconvolution based on the minimization of mutual information.Some properties of the learning algorithm,such as equivariance and stability are also studied.Finally,the simulations are given to illustrate the effectiveness and validity of the proposed algorithm.

  14. Multiplicative Noise Removal using Gradient and Laplacian

    Institute of Scientific and Technical Information of China (English)

    He Lei Pan Zhen-kuan

    2009-01-01

    The variational methods for nmltiplicative noise removal have been received considerable attention in recent years.The traditional models based only on gradient result in staircase effect usually.So a hybrid high-order model based on gradient and Laphcian is proposed for mulfiplicative denoising.In order to avoid the shortcomings of explicit scheme in stability,the Gauss-seidel semi-implicit scheme is adopted.Experiments show that the proposed model can avoid staircase effect during removing multiplicative noise while preserving or enhancing edges.

  15. Gradient Elasticity Formulations for Micro/Nanoshells

    Directory of Open Access Journals (Sweden)

    Bohua Sun

    2014-01-01

    Full Text Available The focus of this paper is on illustrating how to extend the second author’s gradient theory of elasticity to shells. Three formulations are presented based on the implicit gradient elasticity constitutive relation 1 -ld2∇2σij=Cijkl(1-ls2∇2εkl and its two approximations 1+ls2∇2-ld2∇2σij=Cijklεkl and σij=Cijkl(1+ld2∇2-ls2∇2εkl.

  16. Effects of Density Gradients on Braneworld Stars

    Science.gov (United States)

    Ovalle, Jorge

    During the last few years the braneworld consequences on general relativity have been studied with great interest. The implications in both, cosmological and astrophysics scenarios, have been considered for many authors. However there are some aspects of braneworld consequences which have not been clearly elucidated yet. For instance, the role played for density gradients in the astrophysics scenario is not clear so far, leaving thus the study of braneworld stars as one of the most difficult scenarios. Here it is shown an approach which allows the study of density gradients and their consequences through the Weyl fluid produced inside a stellar distributions. Some general aspects are discussed in detail.

  17. Gradient Learning Algorithms for Ontology Computing

    Directory of Open Access Journals (Sweden)

    Wei Gao

    2014-01-01

    Full Text Available The gradient learning model has been raising great attention in view of its promising perspectives for applications in statistics, data dimensionality reducing, and other specific fields. In this paper, we raise a new gradient learning model for ontology similarity measuring and ontology mapping in multidividing setting. The sample error in this setting is given by virtue of the hypothesis space and the trick of ontology dividing operator. Finally, two experiments presented on plant and humanoid robotics field verify the efficiency of the new computation model for ontology similarity measure and ontology mapping applications in multidividing setting.

  18. Reactivity mapping with electrochemical gradients for monitoring reactivity at surfaces in space and time.

    Science.gov (United States)

    Krabbenborg, Sven O; Nicosia, Carlo; Chen, Pengkun; Huskens, Jurriaan

    2013-01-01

    Studying and controlling reactions at surfaces is of great fundamental and applied interest in, among others, biology, electronics and catalysis. Because reaction kinetics is different at surfaces compared with solution, frequently, solution-characterization techniques cannot be used. Here we report solution gradients, prepared by electrochemical means, for controlling and monitoring reactivity at surfaces in space and time. As a proof of principle, electrochemically derived gradients of a reaction parameter (pH) and of a catalyst (Cu(I)) have been employed to make surface gradients on the micron scale and to study the kinetics of the (surface-confined) imine hydrolysis and the copper(I)-catalysed azide-alkyne 1,3-dipolar cycloaddition, respectively. For both systems, the kinetic data were spatially visualized in a two-dimensional reactivity map. In the case of the copper(I)-catalysed azide-alkyne 1,3-dipolar cycloaddition, the reaction order (2) was deduced from it.

  19. Stress Field Analyses of Functionally Gradient Ceramic Tool by FEM

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The cutting properties of the functionally gradient ceramic cutting tools relate closely to the gradient distribution. A cutting model of the functionally gradient ceramic tool is firstly designed in the present paper. The optimum of gradient distribution is obtained by way of the FEM analyses.

  20. Rapid solidification of immiscible alloys

    Energy Technology Data Exchange (ETDEWEB)

    Bosco, Enrica; Rizzi, Paola; Baricco, Marcello E-mail: marcello.baricco@unito.it

    2003-05-01

    Immiscible alloys have been rapidly solidified for the preparation of granular materials with giant magnetoresistance properties. Au-based (Au-Co and Au-Fe) and Cu-based (Cu-Co and Cu-Fe) systems have been investigated. Single supersaturated solid solution has been obtained for Au-Fe, whereas three FCC solid solutions with different Co content have been found for Au-Co. For Cu-Co and Cu-Fe a limit of solubility in Cu has been observed. Ni additions to Cu-Fe strongly enhance solid solubility. A thermodynamic analysis has been used to describe the competition between partition-less solidification and phase separation in undercooled liquid.

  1. Measurement and Analysis of Bath-Side Interfacial Concentration Gradients during Membrane Quenching by Phase Inversion.

    Science.gov (United States)

    Gaides, Gary Edward

    in the film as determined by light transmission) for both rapid and delayed precipitating systems with appropriate changes in a given processing variable was consistent with qualitative mass transfer suggestions and existing model predictions for all conditions examined in this study. In addition, the experimental gradient data for all rapid precipitation cases were universally quantified through a non-dimensionalization procedure using a 2-parameter phenomenological model.

  2. Rapid Airplane Parametric Input Design (RAPID)

    Science.gov (United States)

    Smith, Robert E.

    1995-01-01

    RAPID is a methodology and software system to define a class of airplane configurations and directly evaluate surface grids, volume grids, and grid sensitivity on and about the configurations. A distinguishing characteristic which separates RAPID from other airplane surface modellers is that the output grids and grid sensitivity are directly applicable in CFD analysis. A small set of design parameters and grid control parameters govern the process which is incorporated into interactive software for 'real time' visual analysis and into batch software for the application of optimization technology. The computed surface grids and volume grids are suitable for a wide range of Computational Fluid Dynamics (CFD) simulation. The general airplane configuration has wing, fuselage, horizontal tail, and vertical tail components. The double-delta wing and tail components are manifested by solving a fourth order partial differential equation (PDE) subject to Dirichlet and Neumann boundary conditions. The design parameters are incorporated into the boundary conditions and therefore govern the shapes of the surfaces. The PDE solution yields a smooth transition between boundaries. Surface grids suitable for CFD calculation are created by establishing an H-type topology about the configuration and incorporating grid spacing functions in the PDE equation for the lifting components and the fuselage definition equations. User specified grid parameters govern the location and degree of grid concentration. A two-block volume grid about a configuration is calculated using the Control Point Form (CPF) technique. The interactive software, which runs on Silicon Graphics IRIS workstations, allows design parameters to be continuously varied and the resulting surface grid to be observed in real time. The batch software computes both the surface and volume grids and also computes the sensitivity of the output grid with respect to the input design parameters by applying the precompiler tool

  3. Rapidly progressive Alzheimer disease.

    Science.gov (United States)

    Schmidt, Christian; Wolff, Martin; Weitz, Michael; Bartlau, Thomas; Korth, Carsten; Zerr, Inga

    2011-09-01

    Different rates of progression have been observed among patients with Alzheimer disease. Risk factors that accelerate deterioration have been identified and some are being discussed, such as genetics, comorbidity, and the early appearance of Alzheimer disease motor signs. Progressive forms of Alzheimer disease have been reported with rapid cognitive decline and disease duration of only a few years. This short review aims to provide an overview of the current knowledge of rapidly progressive Alzheimer disease. Furthermore, we suggest that rapid, in this context, should be defined as a Mini-Mental State Examination score decrease of 6 points per year.

  4. Operationele Oceanografie en Rapid Environmental Assessment (Operational Oceanography and Rapid Environmental Assessment)

    Science.gov (United States)

    2008-11-01

    gebruikt worden voor het verkrijgen van een Rapid Enviromental Picture (REP), of worden gebruikt als input voor modellen van de drie-dimensionale (3D...Preparation 2007. J. Mar. systems, REA Special issue , 2009, accepted for publication. [11] Sherman, J., R. Davis, W. B. Owens en J. Valdes (2001), The

  5. ROBUSTNESS OF MORPHOGEN GRADIENTS WITH "BUCKET BRIGADE" TRANSPORT THROUGH MEMBRANE-ASSOCIATED NON-RECEPTORS.

    Science.gov (United States)

    Lei, Jinzhi; Wang, Dongyong; Song, You; Nie, Qing; Wan, Frederic Y M

    2013-05-01

    Robust multiple-fate morphogen gradients are essential for embryo development. Here, we analyze mathematically a model of morphogen gradient (such as Dpp in Drosophila wing imaginal disc) formation in the presence of non-receptors with both diffusion of free morphogens and the movement of morphogens bound to non-receptors. Under the assumption of rapid degradation of unbound morphogen, we introduce a method of functional boundary value problem and prove the existence, uniqueness and linear stability of a biologically acceptable steady-state solution. Next, we investigate the robustness of this steady-state solution with respect to significant changes in the morphogen synthesis rate. We prove that the model is able to produce robust biological morphogen gradients when production and degradation rates of morphogens are large enough and non-receptors are abundant. Our results provide mathematical and biological insight to a mechanism of achieving stable robust long distance morphogen gradients. Key elements of this mechanism are rapid turnover of morphogen to non-receptors of neighoring cells resulting in significant degradation and transport of non-receptor-morphogen complexes, the latter moving downstream through a "bucket brigade" process.

  6. Changes of amino acid gradients in brain tissues induced by microwave irradiation and other means

    Energy Technology Data Exchange (ETDEWEB)

    Baxter, C.F.; Parsons, J.E.; Oh, C.C.; Wasterlain, C.G.; Baldwin, R.A. (Neurochem. Labs, V.A. Med. Ctr. Sepulveda, CA (USA))

    1989-09-01

    Focused microwave irradiation to the head (FMI) has been used extensively by neurochemists for rapid inactivation of enzymatic activity in brain tissues and the preservation, for in vitro analysis, of in vivo substrate concentrations. Periodically the suitability of this technique for regional studies has been questioned. Evidence has now been obtained, on the basis of altered concentration gradients for GABA and taurine from the Substantia Nigra (SN) to an Adjacent Dorsal Area (ADJ), that FMI not only inactivates enzymes, but also facilitates rapid diffusion of small molecules from areas of high concentrations to adjacent areas of lower concentration. To a lesser extent, the implantation of plastic injection cannulas also decreased these concentration gradients. These results offer clear evidence that FMI is ill suited and unreliable for studies designed to map and compare the in vivo regional concentrations of diffusible organic molecules (such as amino acids) in brain tissues. Any invasive technique that compromises membrane barriers is likely to produce smaller similar effects.

  7. Up-gradient transport in a probabilistic transport model

    DEFF Research Database (Denmark)

    Gavnholt, J.; Juul Rasmussen, J.; Garcia, O.E.

    2005-01-01

    The transport of particles or heat against the driving gradient is studied by employing a probabilistic transport model with a characteristic particle step length that depends on the local concentration or heat gradient. When this gradient is larger than a prescribed critical value, the standard....... These results supplement recent works by van Milligen [Phys. Plasmas 11, 3787 (2004)], which applied Levy distributed step sizes in the case of supercritical gradients to obtain the up-gradient transport. (c) 2005 American Institute of Physics....

  8. Annular beam with segmented phase gradients

    Directory of Open Access Journals (Sweden)

    Shubo Cheng

    2016-08-01

    Full Text Available An annular beam with a single uniform-intensity ring and multiple segments of phase gradients is proposed in this paper. Different from the conventional superposed vortices, such as the modulated optical vortices and the collinear superposition of multiple orbital angular momentum modes, the designed annular beam has a doughnut intensity distribution whose radius is independent of the phase distribution of the beam in the imaging plane. The phase distribution along the circumference of the doughnut beam can be segmented with different phase gradients. Similar to a vortex beam, the annular beam can also exert torques and rotate a trapped particle owing to the orbital angular momentum of the beam. As the beam possesses different phase gradients, the rotation velocity of the trapped particle can be varied along the circumference. The simulation and experimental results show that an annular beam with three segments of different phase gradients can rotate particles with controlled velocities. The beam has potential applications in optical trapping and optical information processing.

  9. Marine submicron aerosol gradients, sources and sinks

    Science.gov (United States)

    Ceburnis, Darius; Rinaldi, Matteo; Ovadnevaite, Jurgita; Martucci, Giovanni; Giulianelli, Lara; O'Dowd, Colin D.

    2016-10-01

    Aerosol principal sources and sinks over eastern North Atlantic waters were studied through the deployment of an aerosol chemistry gradient sampling system. The chemical gradients of primary and secondary aerosol components - specifically, sea salt (SS), water-insoluble organic matter (WIOM), water-soluble organic matter (WSOM), nitrate, ammonium, oxalate, amines, methanesulfonic acid (MSA) and water-soluble organic nitrogen (WSON) - were examined in great detail. Sea salt fluxes were estimated by the boundary layer box model and ranged from 0.3 to 3.5 ng m-2 s-1 over the wind speed range of 5-12 m s-1 and compared well with the derived fluxes from existing sea salt source parameterisations. The observed seasonal pattern of sea salt gradients was mainly driven by wind stress in addition to the yet unquantified effect of marine OM modifying fractional contributions of SS and OM in sea spray. WIOM gradients were a complex combination of rising and waning biological activity, especially in the flux footprint area, and wind-driven primary sea spray production supporting the coupling of recently developed sea spray and marine OM parameterisations.

  10. Gradient dynamics and entropy production maximization

    CERN Document Server

    Janečka, Adam

    2016-01-01

    Gradient dynamics describes irreversible evolution by means of a dissipation potential, which leads to several advantageous features like Maxwell--Onsager relations, distinguishing between thermodynamic forces and fluxes or geometrical interpretation of the dynamics. Entropy production maximization is a powerful tool for predicting constitutive relations in engineering. In this paper, both approaches are compared and their shortcomings and advantages are discussed.

  11. Gradient realization of nonlinear control systems

    NARCIS (Netherlands)

    Cortes monforte, J.; Cortés, J.; Crouch, P.E.; Astolfi, A.; van der Schaft, Arjan; Gordillo, F.

    2003-01-01

    We investigate necessary and su?cient conditions under which a nonlinear afine control system with outputs can be written as a gradient control system corresponding to some pseudo-Riemannian metric defined on the state space. The results rely on a suitable notion of compatibility of the system with

  12. Convergence of approximations of monotone gradient systems

    OpenAIRE

    Zambotti, Lorenzo

    2006-01-01

    We consider stochastic differential equations in a Hilbert space, perturbed by the gradient of a convex potential. We investigate the problem of convergence of a sequence of such processes. We propose applications of this method to reflecting O.U. processes in infinite dimension, to stochastic partial differential equations with reflection of Cahn-Hilliard type and to interface models.

  13. Velocity gradients and microturbulence in Cepheids.

    Science.gov (United States)

    Karp, A. H.

    1973-01-01

    Variations of the microturbulent velocity with phase and height in the atmosphere have been reported in classical Cepheids. It is shown that these effects can be understood in terms of variations of the velocity gradient in the atmospheres of these stars.

  14. On the Vertical Gradient in CO2

    Science.gov (United States)

    Stine, A. R.; Fung, I. Y.

    2008-12-01

    Attempts to constrain surface fluxes of carbon from atmospheric measurements of carbon dioxide have primarily focused on surface boundary layer measurements, because information about surface fluxes is least diluted close to the locations where the fluxes occur. However, errors in model ventilation of air in the vertical can be misinterpreted as local surface fluxes. Satellites which measure column integrated CO2 are expected to represent a major advance in part because they observe the entire atmospheric column. Recent work has highlighted the fact that vertical gradients in carbon concentrations can give us information about where vertical mixing errors are likely to be misinterpreted as local surface fluxes, but passive tracer evidence suggests that models that capture vertical profiles on the ocean do poorly on the land (and vice versa), suggesting that the problem of correctly treating vertical mixing in inverse studies is more fundamental than picking the "best" model. We consider observations of the vertical gradient in CO2 from aircrafts and from a comparison of satellites that observe in the near infrared (which observe the column integrated CO2 field) and the thermal infrared (which observe the upper troposphere). We evaluate the feasibility of using these satellites for determining the vertical gradient in CO2. We examine how observations of the vertical gradient of CO2 allow us to differentiate the imprint of vertical mixing and the imprint in surface fluxes on the observed field of atmospheric CO2.

  15. Gradient based filtering of digital elevation models

    DEFF Research Database (Denmark)

    Knudsen, Thomas; Andersen, Rune Carbuhn

    We present a filtering method for digital terrain models (DTMs). The method is based on mathematical morphological filtering within gradient (slope) defined domains. The intention with the filtering procedure is to improbé the cartographic quality of height contours generated from a DTM based on ...... in the landscape are washed out and misrepresented....

  16. Instabilities in power law gradient hardening materials

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Tvergaard, Viggo

    2005-01-01

    Tension and compression instabilities are investigated for specimens with dimensions in the micron range. A finite strain generalization of a higher order strain gradient plasticity theory is implemented in a finite element scheme capable of modeling power law hardening materials. Effects...

  17. Gradient computation for VTI acoustic wavefield tomography

    KAUST Repository

    Li, Vladimir

    2016-09-06

    Wavefield tomography can handle complex subsurface geology better than ray-based techniques and, ultimately, provide a higher resolution. Here, we implement forward and adjoint wavefield extrapolation for VTI (transversely isotropic with a vertical symmetry axis) media using a pseudospectral operator that employes a separable approximation of the P-wave dispersion relation. This operator is employed to derive the gradients of the differential semblance optimization (DSO) and modified stack-power objective functions. We also obtain the gradient expressions for the data-domain objective function, which can incorporate borehole information necessary for stable VTI velocity analysis. These gradients are compared to the ones obtained with a space-time finite-difference (FD) scheme for a system of coupled wave equations. Whereas the kernels computed with the two wave-equation operators are similar, the pseudospectral method is not hampered by the imprint of the shear-wave artifact. Numerical examples also show that the modified stack-power objective function produces cleaner gradients than the more conventional DSO operator.

  18. A latitudinal phylogeographic diversity gradient in birds.

    Science.gov (United States)

    Smith, Brian Tilston; Seeholzer, Glenn F; Harvey, Michael G; Cuervo, Andrés M; Brumfield, Robb T

    2017-04-01

    High tropical species diversity is often attributed to evolutionary dynamics over long timescales. It is possible, however, that latitudinal variation in diversification begins when divergence occurs within species. Phylogeographic data capture this initial stage of diversification in which populations become geographically isolated and begin to differentiate genetically. There is limited understanding of the broader implications of intraspecific diversification because comparative analyses have focused on species inhabiting and evolving in restricted regions and environments. Here, we scale comparative phylogeography up to the hemisphere level and examine whether the processes driving latitudinal differences in species diversity are also evident within species. We collected genetic data for 210 New World bird species distributed across a broad latitudinal gradient and estimated a suite of metrics characterizing phylogeographic history. We found that lower latitude species had, on average, greater phylogeographic diversity than higher latitude species and that intraspecific diversity showed evidence of greater persistence in the tropics. Factors associated with species ecologies, life histories, and habitats explained little of the variation in phylogeographic structure across the latitudinal gradient. Our results suggest that the latitudinal gradient in species richness originates, at least partly, from population-level processes within species and are consistent with hypotheses implicating age and environmental stability in the formation of diversity gradients. Comparative phylogeographic analyses scaled up to large geographic regions and hundreds of species can show connections between population-level processes and broad-scale species-richness patterns.

  19. Annular beam with segmented phase gradients

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Shubo; Wu, Liang [School of Physics and Electronics, Central South University, Changsha, Hunan 410083 (China); Tao, Shaohua, E-mail: eshtao@csu.edu.cn [School of Physics and Electronics, Central South University, Changsha, Hunan 410083 (China); Hunan Key Laboratory for Super-microstructure and Ultrafast Process, School of Physics and Electronics, Central South University, Changsha, Hunan 410083 (China)

    2016-08-15

    An annular beam with a single uniform-intensity ring and multiple segments of phase gradients is proposed in this paper. Different from the conventional superposed vortices, such as the modulated optical vortices and the collinear superposition of multiple orbital angular momentum modes, the designed annular beam has a doughnut intensity distribution whose radius is independent of the phase distribution of the beam in the imaging plane. The phase distribution along the circumference of the doughnut beam can be segmented with different phase gradients. Similar to a vortex beam, the annular beam can also exert torques and rotate a trapped particle owing to the orbital angular momentum of the beam. As the beam possesses different phase gradients, the rotation velocity of the trapped particle can be varied along the circumference. The simulation and experimental results show that an annular beam with three segments of different phase gradients can rotate particles with controlled velocities. The beam has potential applications in optical trapping and optical information processing.

  20. Gradient based filtering of digital elevation models

    DEFF Research Database (Denmark)

    Knudsen, Thomas; Andersen, Rune Carbuhn

    We present a filtering method for digital terrain models (DTMs). The method is based on mathematical morphological filtering within gradient (slope) defined domains. The intention with the filtering procedure is to improbé the cartographic quality of height contours generated from a DTM based...

  1. Subspace learning from image gradient orientations

    NARCIS (Netherlands)

    Tzimiropoulos, Georgios; Zafeiriou, Stefanos; Pantic, Maja

    2012-01-01

    We introduce the notion of subspace learning from image gradient orientations for appearance-based object recognition. As image data is typically noisy and noise is substantially different from Gaussian, traditional subspace learning from pixel intensities fails very often to estimate reliably the l

  2. Lactate uptake against a concentration gradient

    DEFF Research Database (Denmark)

    Nordström, Carl-Henrik; Nielsen, Troels Halfeld; Nielsen, Hans Boye

    2014-01-01

    ]) concludes that lactate may be transported across the blood brain barrier into the brain against a concentration gradient. Unfortunately the authors have misinterpreted the concept of analytical imprecision and their conclusion is based on analytical artifact. As the topic of lactate transport into the brain...

  3. Proton gradients at the origin of life.

    Science.gov (United States)

    Lane, Nick

    2017-06-01

    Chemiosmotic coupling - the harnessing of electrochemical ion gradients across membranes to drive metabolism - is as universally conserved as the genetic code. As argued previously in these pages, such deep conservation suggests that ion gradients arose early in evolution, and might have played a role in the origin of life. Alkaline hydrothermal vents harbour pH gradients of similar polarity and magnitude to those employed by modern cells, one of many properties that make them attractive models for life's origin. Their congruence with the physiology of anaerobic autotrophs that use the acetyl CoA pathway to fix CO2 gives the alkaline vent model broad appeal to biologists. Recently, however, a paper by Baz Jackson criticized the hypothesis, concluding that natural pH gradients were unlikely to have played any role in the origin of life. Unfortunately, Jackson mainly criticized his own interpretations of the theory, not what the literature says. This counterpoint is intended to set the record straight. © 2017 WILEY Periodicals, Inc.

  4. Analysis of magnetic gradients to study gravitropism.

    Science.gov (United States)

    Hasenstein, Karl H; John, Susan; Scherp, Peter; Povinelli, Daniel; Mopper, Susan

    2013-01-01

    Gravitropism typically is generated by dense particles that respond to gravity. Experimental stimulation by high-gradient magnetic fields provides a new approach to selectively manipulate the gravisensing system. The movement of corn, wheat, and potato starch grains in suspension was examined with videomicroscopy during parabolic flights that generated 20 to 25 s of weightlessness. During weightlessness, a magnetic gradient was generated by inserting a wedge into a uniform, external magnetic field that caused repulsion of starch grains. The resultant velocity of movement was compared with the velocity of sedimentation under 1 g conditions. The high-gradient magnetic fields repelled the starch grains and generated a force of at least 0.6 g. Different wedge shapes significantly affected starch velocity and directionality of movement. Magnetic gradients are able to move diamagnetic compounds under weightless or microgravity conditions and serve as directional stimulus during seed germination in low-gravity environments. Further work can determine whether gravity sensing is based on force or contact between amyloplasts and statocyte membrane system.

  5. CMB anisotropies from a gradient mode

    Science.gov (United States)

    Mirbabayi, Mehrdad; Zaldarriaga, Matias

    2015-03-01

    A linear gradient mode must have no observable dynamical effect on short distance physics. We confirm this by showing that if there was such a gradient mode extending across the whole observable Universe, it would not cause any hemispherical asymmetry in the power of CMB anisotropies, as long as Maldacena's consistency condition is satisfied. To study the effect of the long wavelength mode on short wavelength modes, we generalize the existing second order Sachs-Wolfe formula in the squeezed limit to include a gradient in the long mode and to account for the change in the location of the last scattering surface induced by this mode. Next, we consider effects that are of second order in the long mode. A gradient mode Φ = qṡx generated in Single-field inflation is shown to induce an observable quadrupole moment. For instance, in a matter-dominated model it is equal to Q = 5(qṡx)2/18. This quadrupole can be canceled by superposition of a quadratic perturbation. The result is shown to be a nonlinear extension of Weinberg's adiabatic modes: a long-wavelength physical mode which looks locally like a coordinate transformation.

  6. Hydropower RAPID Toolkit

    Energy Technology Data Exchange (ETDEWEB)

    2016-12-01

    This fact sheet provides a brief overview of the U.S. Department of Energy (DOE) Hydropower Regulatory and Permitting Information Desktop (RAPID) Toolkit including its capabilities, features, and benefits.

  7. SAP Sector Develops Rapidly

    Institute of Scientific and Technical Information of China (English)

    Zheng Chengwang

    2007-01-01

    @@ Stable demand growth internationally Super absorbent polymers (SAP) feature high water absorption, high water retention, rapid water absorption, great expanding power,strong thickening, strong anchoring and excellent elasticity.

  8. Rapid Lead Screening Test

    Science.gov (United States)

    ... Vitro Diagnostics Tests Used In Clinical Care Rapid Lead Screening Test Share Tweet Linkedin Pin it More ... reducing the need for a follow-up visit. Lead Risk Links Centers for Disease Control and Prevention ( ...

  9. Geothermal gradients map of Hokkaido; Hokkaido no chion kobaizu ni tsuite

    Energy Technology Data Exchange (ETDEWEB)

    Akita, F.; Matsunami, T.; Wakahama, H. [Hokkaido Geological Survey, Sapporo (Japan)

    1997-06-15

    This paper outlines the newly prepared geothermal gradient map (GGM) of Hokkaido which is important for survey on geothermal and hot spring resources. The temperature data of 687 wells were compiled by data collection and field survey. The geothermal gradient was calculated from the ratio of the temperature difference between the bottom (deepest well log) and the ground surface (10degC) to a bottom depth. GGM was prepared using data of 85 wells which show real geothermal temperatures through conductive temperature profiles, or SBHT (static bottom hole temperature) calculation is possible. Geological profiles were classified into three types based on base rocks. The thermal structure of GGM was clearly divided into a high geothermal gradient over 10degC/100m, and a low one within 3degC/100m. The former showed active volcano and high geothermal areas, while the latter showed a volcanic front arc area. This underground temperature structure relates to the formation process of volcanos and the origin of magma, and is also similar to the trend of a crust thermal flow rate. The geothermal gradient increases with a decrease in Curie point depth. 26 refs., 10 figs., 2 tabs.

  10. Effect of semen extender and density gradient centrifugation on the motility and fertility of turkey spermatozoa.

    Science.gov (United States)

    Morrell, J M; Persson, B; Tjellström, H; Laessker, A; Nilsson, H; Danilova, M; Holmes, P V

    2005-12-01

    In the absence of commercially viable methods for cryopreserving turkey spermatozoa, new processing methods are required to extend the functional life of stored turkey spermatozoa for artificial insemination. The present study evaluates the efficacy of a new extender (Turkey Semen Extend) and investigates the use of density gradient centrifugation in processing turkey spermatozoa for artificial insemination. The new extender is compared with two commercially available turkey semen extenders, Beltsville Poultry Semen Extender and Ovodyl. Turkey spermatozoa in Turkey Semen Extend were still motile 20 h after collection, representing a considerable improvement over the other semen extenders (40%, 0% and 8% for Turkey Semen Extend, Beltsville Poultry Semen Extender and Ovodyl, respectively). A field trial on a commercial turkey farm showed improved fertilization rates following insemination of turkey hens with semen extended in Turkey Semen Extend (89.7%) compared with Beltsville Poultry Semen Extender (86.9%). This difference is statistically significant (p < 0.05). Processing on a density gradient, optimized for turkey spermatozoa, also increased sperm survival (50% gradient-prepared spermatozoa still motile after 18 h compared with <10% non-processed spermatozoa). Preliminary studies indicate that gradient preparation of spermatozoa may aid survival during cryopreservation.

  11. Development of High-Gradient Dielectric Laser-Driven Particle Accelerator Structures

    Energy Technology Data Exchange (ETDEWEB)

    Byer, Robert L.

    2013-11-07

    The thrust of Stanford's program is to conduct research on high-gradient dielectric accelerator structures driven with high repetition-rate, tabletop infrared lasers. The close collaboration between Stanford and SLAC (Stanford Linear Accelerator Center) is critical to the success of this project, because it provides a unique environment where prototype dielectric accelerator structures can be rapidly fabricated and tested with a relativistic electron beam.

  12. GPS, GNSS, and Ionospheric Density Gradients

    Science.gov (United States)

    Kintner, P. M.; O'Hanlon, B.; Humphreys, T. E.

    2009-12-01

    Ionospheric density and density gradients affect GNSS signals in two ways. They can introduce ranging errors or irregularities that form on the density gradients producing scintillation. Here we focus on the issue of ranging errors. There are two approaches to mitigating ranging errors produced by ionospheric density gradients which can be 20-30 m during major magnetic storms. The first approach is to use a reference receiver(s) to determine the ionospheric contribution to ranging errors. The ranging error is then transmitted to the user for correction within the mobile receiver. This approach is frequently referred to as differential GPS and, when multiple reference receivers are used, the system is referred to as an augmentation system. This approach is vulnerable to ionospheric gradients depending on the reference receiver spacing(s) and latency in applying the correction within the mobile receiver. The second approach is to transmit navigation signals at two frequencies and then use the relative delay between the two signals to both estimate the ranging error and calculate the correct range. Currently the dual frequency technique is used by US military receivers with an encryption key and some civilian receivers which must be stationary and average over times long compared to those required for navigation. However, the technology of space based radio navigation is changing. GPS will soon be a system with three frequencies and multiple codes. Furthermore Europe, Russia, and China are developing independent systems to complement and compete with GPS while India and Japan are developing local systems to enhance GPS performance in their regions. In this talk we address two questions. How do density gradients affect augmentation systems including the social consequences and will the new GPS/GNSS systems with multiple civilian frequencies be able to remove ionospheric errors. The answers are not at all clear.

  13. Miniaturization of speckle interferometry for rapid strain analysis

    Science.gov (United States)

    Wegner, Ronny; Ettemeyer, Andreas

    1999-09-01

    Today's industry demands high-performance components meeting toughest mechanical features and ultimate safety standards. Especially in automotive and aircraft industry the development focuses on tailor-made design and solutions according to customer specifications. To reconcile economy, light-weight construction has become a key issue. Many companies are looking for new advanced strain/stress analysis techniques to improve cost efficiency and the limitations of classical methods. Detection of weak points and fatigue tests are carried out mainly with strain gauges which need careful application and experience. ESPI (electronic speckle pattern interferometry) allows a rapid, full field and 3D-measurement without contact. This paper presents the principle and application of a new miniaturized laser optical sensor combining contour and deformation measurement. In its basic employment ESPI is an interferometric method measuring deformations at modern working materials with high accuracy. Here also a module for contouring was developed and integrated into a single interferometer. Therefore even at complex components it is possible to measure and display strain-fields and -gradients with respect to the underlying contour. The new sensor is a unique device for flexible strain-analysis at welded-materials, extrusions, engines, car-bodies, etc. Without preparation and due to the full field and 3D- measurement 'hot spots' are shown, reducing the testing procedure and increasing the reliability of the complex component testing significantly. In this paper the recent development of a miniaturized ESPI-interferometer for strain and stress measurement is described. Advanced features according to classical techniques are specified and new applications in material and component testing are presented.

  14. Remote loading of diclofenac, insulin and fluorescein isothiocyanate labeled insulin into liposomes by pH and acetate gradient methods.

    Science.gov (United States)

    Hwang, S H; Maitani, Y; Qi, X R; Takayama, K; Nagai, T

    1999-03-01

    Remote loading of the model drugs diclofenac, insulin and fluorescein isothiocyanate labeled insulin (FITC-insulin) into liposomes by formation of transmembrane gradients were examined. A trapping efficiency of almost 100% was obtained for liposomal diclofenac, by the calcium acetate gradient method, whereas liposomes prepared by the conventional reverse-phase evaporation vesicle method had 1-8% trapping efficiencies. Soybean-derived sterol was a better stabilizer of the dipalmitoylphosphatidylcholine bilayer membrane than cholesterol, as shown from trapping efficiencies and drug release. The pH gradient method resulted in a 5-50% of FITC-insulin liposomal trapping efficiency, while insulin could not be loaded by this method. Liposomes released calcein in response to insulin, showing insulin interacts with the liposomal membrane in the presence of a transmembrane gradient. The present work has demonstrated a remote loading method for weak acids such as diclofenac into liposomes by the acetate gradient method. From the result of remote loading of FITC-insulin into liposomes by the pH gradient method, this method may be available for the preparation of liposomal peptides.

  15. Rapid Separation of Fission Product 141La

    Institute of Scientific and Technical Information of China (English)

    XIA; Wen; YE; Hong-sheng; LIN; Min; CHEN; Ke-sheng; XU; Li-jun; ZHANG; Wei-dong; CHEN; Yi-zhen

    2013-01-01

    141La was separated and purified from fission products in this work for physical measurements aimed at improving the accuracy of its decay parameters.As the impact of 142La and other fission products,cesium(141Cs,142Cs included)was rapid separated from the fission products,141Cs and 142Ba separation was prepared after a cooling time about 25 s when 142Cs decays to daughter 142Ba,141La purification then

  16. Death Valley Lower Carbonate Aquifer Monitoring Program Wells Down Gradient of the Proposed Yucca Mountain Nuclear Waste Repository, U. S. Department of Energy Grant DE-RW0000233 2010 Project Report, prepared by The Hydrodynamics Group, LLC for Inyo County Yucca Mountain Repository Assessment Office

    Energy Technology Data Exchange (ETDEWEB)

    King, Michael J; Bredehoeft, John D., Dr.

    2010-09-03

    Inyo County completed the first year of the U.S. Department of Energy Grant Agreement No. DE-RW0000233. This report presents the results of research conducted within this Grant agreement in the context of Inyo County's Yucca Mountain oversight program goals and objectives. The Hydrodynamics Group, LLC prepared this report for Inyo County Yucca Mountain Repository Assessment Office. The overall goal of Inyo County's Yucca Mountain research program is the evaluation of far-field issues related to potential transport, by ground water, of radionuclide into Inyo County, including Death Valley, and the evaluation of a connection between the Lower Carbonate Aquifer (LCA) and the biosphere. Data collected within the Grant is included in interpretive illustrations and discussions of the results of our analysis. The centeral elements of this Grant prgoram was the drilling of exploratory wells, geophysical surveys, geological mapping of the Southern Funeral Mountain Range. The cullimination of this research was 1) a numerical ground water model of the Southern Funeral Mountain Range demonstrating the potential of a hydraulic connection between the LCA and the major springs in the Furnace Creek area of Death Valley, and 2) a numerical ground water model of the Amargosa Valley to evaluate the potential for radionuclide transport from Yucca Mountain to Inyo County, California. The report provides a description of research and activities performed by The Hydrodynamics Group, LLC on behalf of Inyo County, and copies of key work products in attachments to this report.

  17. Study of a Liquid Plug-Flow Thermal Cycling Technique Using a Temperature Gradient-Based Actuator

    Directory of Open Access Journals (Sweden)

    Yusuke Fuchiwaki

    2014-10-01

    Full Text Available Easy-to-use thermal cycling for performing rapid and small-volume DNA amplification on a single chip has attracted great interest in the area of rapid field detection of biological agents. For this purpose, as a more practical alternative to conventional continuous flow thermal cycling, liquid plug-flow thermal cycling utilizes a thermal gradient generated in a serpentine rectangular flow microchannel as an actuator. The transit time and flow speed of the plug flow varied drastically in each temperature zone due to the difference in the tension at the interface between temperature gradients. According to thermal distribution analyses in microfluidics, the plug flow allowed for a slow heating process, but a fast cooling process. The thermal cycle of the microfluid was consistent with the recommended temperature gradient for PCR. Indeed, amplification efficiency of the plug flow was superior to continuous flow PCR, and provided an impressive improvement over previously-reported flow microchannel thermal cycling techniques.

  18. Thermal Gradient During Vacuum-Deposition Dramatically Enhances Charge Transport in Organic Semiconductors: Toward High-Performance N-Type Organic Field-Effect Transistors.

    Science.gov (United States)

    Kim, Joo-Hyun; Han, Singu; Jeong, Heejeong; Jang, Hayeong; Baek, Seolhee; Hu, Junbeom; Lee, Myungkyun; Choi, Byungwoo; Lee, Hwa Sung

    2017-03-09

    A thermal gradient distribution was applied to a substrate during the growth of a vacuum-deposited n-type organic semiconductor (OSC) film prepared from N,N'-bis(2-ethylhexyl)-1,7-dicyanoperylene-3,4:9,10-bis(dicarboxyimide) (PDI-CN2), and the electrical performances of the films deployed in organic field-effect transistors (OFETs) were characterized. The temperature gradient at the surface was controlled by tilting the substrate, which varied the temperature one-dimensionally between the heated bottom substrate and the cooled upper substrate. The vacuum-deposited OSC molecules diffused and rearranged on the surface according to the substrate temperature gradient, producing directional crystalline and grain structures in the PDI-CN2 film. The morphological and crystalline structures of the PDI-CN2 thin films grown under a vertical temperature gradient were dramatically enhanced, comparing with the structures obtained from either uniformly heated films or films prepared under a horizontally applied temperature gradient. The field effect mobilities of the PDI-CN2-FETs prepared using the vertically applied temperature gradient were as high as 0.59 cm(2) V(-1) s(-1), more than a factor of 2 higher than the mobility of 0.25 cm(2) V(-1) s(-1) submitted to conventional thermal annealing and the mobility of 0.29 cm(2) V(-1) s(-1) from the horizontally applied temperature gradient.

  19. Effect of pressure gradients on Gortler instability

    Science.gov (United States)

    Ragab, S. A.; Nayfeh, A. H.

    1980-01-01

    Gortler instability for boundary-layer flows over generally curved walls is considered. The full linearized disturbance equations are obtained in an orthogonal curvilinear coordinate system. A perturbation procedure to account for second-order effects is used to determine the effects of the displacement thickness and the variation of the streamline curvature on the neutral stability of the Blasius flow. The pressure gradient in the mean flow is accounted for by solving the nonsimilar boundary-layer equations. Growth rates are obtained for the actual mean flow and the Falkner-Skan flows. The results demonstrate the strong influence of the pressure gradient and the nonsimilarity of the basic flow on the stability characteristics.

  20. Hybrid high gradient permanent magnet quadrupole

    Science.gov (United States)

    N'gotta, P.; Le Bec, G.; Chavanne, J.

    2016-12-01

    This paper presents an innovative compact permanent magnet quadrupole with a strong gradient for potential use in future light source lattices. Its magnetic structure includes simple mechanical parts, rectangular permanent magnet blocks and soft iron poles. It has a wide aperture in the horizontal plane to accommodate an x-ray beam port, a common constraint in storage ring-based light sources. This specificity introduces field quality deterioration because of the resulting truncation of the poles; a suitable field quality can be restored with an optimized pole shape. A 82 T /m prototype with a bore radius of 12 mm and a 10 mm vertical gap between poles has been constructed and magnetically characterized. Gradient inhomogeneities better than 10-3 in the good field region were obtained after the installation of special shims.

  1. Gradient evolution for potential vorticity flows

    Directory of Open Access Journals (Sweden)

    S. Balasuriya

    2001-01-01

    Full Text Available Two-dimensional unsteady incompressible flows in which the potential vorticity (PV plays a key role are examined in this study, through the development of the evolution equation for the PV gradient. For the case where the PV is conserved, precise statements concerning topology-conservation are presented. While establishing some intuitively well-known results (the numbers of eddies and saddles is conserved, other less obvious consequences (PV patches cannot be generated, some types of Lagrangian and Eulerian entities are equivalent are obtained. This approach enables an improvement on an integrability result for PV conserving flows (if there were no PV patches at time zero, the flow would be integrable. The evolution of the PV gradient is also determined for the nonconservative case, and a plausible experiment for estimating eddy diffusivity is suggested. The theory is applied to an analytical diffusive Rossby wave example.

  2. Sequential pattern formation governed by signaling gradients

    CERN Document Server

    Jörg, David J; Jülicher, Frank

    2016-01-01

    Rhythmic and sequential segmentation of the embryonic body plan is a vital developmental patterning process in all vertebrate species. However, a theoretical framework capturing the emergence of dynamic patterns of gene expression from the interplay of cell oscillations with tissue elongation and shortening and with signaling gradients, is still missing. Here we show that a set of coupled genetic oscillators in an elongating tissue that is regulated by diffusing and advected signaling molecules can account for segmentation as a self-organized patterning process. This system can form a finite number of segments and the dynamics of segmentation and the total number of segments formed depend strongly on kinetic parameters describing tissue elongation and signaling molecules. The model accounts for existing experimental perturbations to signaling gradients, and makes testable predictions about novel perturbations. The variety of different patterns formed in our model can account for the variability of segmentatio...

  3. Sequential pattern formation governed by signaling gradients

    Science.gov (United States)

    Jörg, David J.; Oates, Andrew C.; Jülicher, Frank

    2016-10-01

    Rhythmic and sequential segmentation of the embryonic body plan is a vital developmental patterning process in all vertebrate species. However, a theoretical framework capturing the emergence of dynamic patterns of gene expression from the interplay of cell oscillations with tissue elongation and shortening and with signaling gradients, is still missing. Here we show that a set of coupled genetic oscillators in an elongating tissue that is regulated by diffusing and advected signaling molecules can account for segmentation as a self-organized patterning process. This system can form a finite number of segments and the dynamics of segmentation and the total number of segments formed depend strongly on kinetic parameters describing tissue elongation and signaling molecules. The model accounts for existing experimental perturbations to signaling gradients, and makes testable predictions about novel perturbations. The variety of different patterns formed in our model can account for the variability of segmentation between different animal species.

  4. Temperature gradient driven lasing and stimulated cooling

    CERN Document Server

    Sandner, K

    2012-01-01

    A laser can be understood as thermodynamic engine converting heat to a coherent single mode field close to Carnot efficiency. From this perspective spectral shaping of the excitation light generates a higher effective temperature on the pump than on the gain transition. Here, using a toy model of a quantum well structure with two suitably designed tunnel-coupled wells kept at different temperature, we study a laser operated on an actual spatial temperature gradient between pump and gain region. We predict gain and narrow band laser emission for a sufficient temperature gradient and resonator quality. Lasing appears concurrent with amplified heat flow and points to a new form of stimulated solid state cooling. Such a mechanism could raise the operating temperature limit of quantum cascade lasers by substituting phonon emission driven injection, which generates intrinsic heat, by an extended model with phonon absorption steps.

  5. Electron profile stiffness and critical gradient studies

    Science.gov (United States)

    DeBoo, J. C.; Petty, C. C.; White, A. E.; Burrell, K. H.; Doyle, E. J.; Hillesheim, J. C.; Holland, C.; McKee, G. R.; Rhodes, T. L.; Schmitz, L.; Smith, S. P.; Wang, G.; Zeng, L.

    2012-08-01

    Electron profile stiffness was studied in DIII-D L-mode discharges by systematically varying the heat flux in a narrow region with electron cyclotron heating and measuring the local change produced in ∇Te. Electron stiffness was found to slowly increase with toroidal rotation velocity. A critical inverse temperature gradient scale length 1/LC ˜ 3 m-1 was identified at ρ =0.6 and found to be independent of rotation. Both the heat pulse diffusivity and the power balance diffusivity, the latter determined by integrating the measured dependence of the heat pulse diffusivity on -∇Te, were fit reasonably well by a model containing a critical inverse temperature gradient scale length and varying linearly with 1/LT above the threshold.

  6. Opinion formation models on a gradient.

    Directory of Open Access Journals (Sweden)

    Michael T Gastner

    Full Text Available Statistical physicists have become interested in models of collective social behavior such as opinion formation, where individuals change their inherently preferred opinion if their friends disagree. Real preferences often depend on regional cultural differences, which we model here as a spatial gradient g in the initial opinion. The gradient does not only add reality to the model. It can also reveal that opinion clusters in two dimensions are typically in the standard (i.e., independent percolation universality class, thus settling a recent controversy about a non-consensus model. However, using analytical and numerical tools, we also present a model where the width of the transition between opinions scales proportional g(-1/4, not proportional g(-4/7 as in independent percolation, and the cluster size distribution is consistent with first-order percolation.

  7. Stochastic gradient descent on Riemannian manifolds

    CERN Document Server

    Bonnabel, Silvere

    2011-01-01

    Stochastic gradient descent is a simple appproach to find the local minima of a function whose evaluations are corrupted by noise. In this paper, mostly motivated by machine learning applications, we develop a procedure extending stochastic gradient descent algorithms to the case where the function is defined on a Riemannian manifold. We prove that, as in the Euclidian case, the descent algorithm converges to a critical point of the cost function. The algorithm has numerous potential applications, and we show several well-known algorithms can be cast in our versatile geometric framework. We also address the gain tuning issue in connection with the tools of the recent theory of symmetry-preserving observers.

  8. Optimizing sampling approaches along ecological gradients

    DEFF Research Database (Denmark)

    Schweiger, Andreas; Irl, Severin D. H.; Steinbauer, Manuel

    2016-01-01

    1. Natural scientists and especially ecologists use manipulative experiments or field observations along gradients to differentiate patterns driven by processes from those caused by random noise. A well-conceived sampling design is essential for identifying, analysing and reporting underlying...... patterns in a statistically solid and reproducible manner, given the normal restrictions in labour, time and money. However, a technical guideline about an adequate sampling design to maximize prediction success under restricted resources is lacking. This study aims at developing such a solid...... and reproducible guideline for sampling along gradients in all fields of ecology and science in general. 2. We conducted simulations with artificial data for five common response types known in ecology, each represented by a simple function (no response, linear, exponential, symmetric unimodal and asymmetric...

  9. Rapid, simple and stability-indicating determination of polyhexamethylene biguanide in liquid and gel-like dosage forms by liquid chromatography with diode-array detection

    Institute of Scientific and Technical Information of China (English)

    Markus Küsters; Sören Beyer; Stephan Kutscher; Harald Schlesinger; Michael Gerhartz

    2013-01-01

    A rapid and simple method for the determination of polyhexamethylene biguanide (polyhexanide, PHMB) in liquid and gel-like pharmaceutical formulations by means of high performance liquid chromatography coupled to diode-array detection (HPLC-DAD) was developed. Best separation was achieved using a cyanopropyl bonded phase (Agilent Zorbax Eclipse XDB-CN column 4.6 mm75 mm with particle size of 3.5 mm) as well as gradient elution consisting of acetonitrile/deionized water at a flow rate of 1.0 mL/min. The optimized and applied chromatographic conditions permitted separation of polyhexanide from interacting matrix with subsequent detection at a wavelength of 235 nm with good sensitivity. The method validation was carried out with regard to the guidelines for analytical procedures demanded by the International Conference on Harmonisation (ICH). Mean recoveries of 102% and 101% for gel-like as well as liquid preparations were obtained. Suitable repeatability as well as intermediate precision could be achieved with limits of detection r0.004 mg/mL for both formulations, equivalent to r0.004% PHMB concerning sample preparation. Determination of PHMB was accomplished without tedious sample preparation. Interacting matrix could be eliminated by the chromatographic procedure with excellent performance of system suitability. All analytical requirements were fulfilled permitting a reliable and precise determination of PHMB in pharmaceuticals. Furthermore, the developed method was applied to stability testing of pharmaceutical preparations containing PHMB.

  10. Fluorescence correlation spectroscopy in laser gradient field

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Fluorescence correlation spectroscopy (FCS) is capable of probing dynamic processes in living biological systems. From photon fluctuation of fluorescing particles which diffuse through a small detection volume, FCS reveals information on the concentration and the structure of the particles, as well as information on microscopic environment.In this note, we study the radiation forces experienced by Rayleigh particles in a laser field in details, and analyze the effects of gradient field on FCS measurements.

  11. Broadband mode conversion via gradient index metamaterials.

    Science.gov (United States)

    Wang, HaiXiao; Xu, YaDong; Genevet, Patrice; Jiang, Jian-Hua; Chen, HuanYang

    2016-04-21

    We propose a design for broadband waveguide mode conversion based on gradient index metamaterials (GIMs). Numerical simulations demonstrate that the zeroth order of transverse magnetic mode or the first order of transverse electric mode (TM0/TE1) can be converted into the first order of transverse magnetic mode or the second order of transverse electric mode (TM1/TE2) for a broadband of frequencies. As an application, an asymmetric propagation is achieved by integrating zero index metamaterials inside the GIM waveguide.

  12. Fracture driven by a Thermal Gradient

    CERN Document Server

    Pla, O

    1995-01-01

    Motivated by recent experiments by Yuse and Sano (Nature, 362, 329 (1993)), we propose a discrete model of linear springs for studying fracture in thin and elastically isotropic brittle films. The method enables us to draw a map of the stresses in the material. Cracks generated by the model, imposing a moving thermal gradient in the material, can branch or wiggle depending on the driving parameters. The results may be used to compare with other recent theoretical work, or to design future experiments.

  13. Dual gradient drilling - simulations during connection operations

    OpenAIRE

    Time, André

    2014-01-01

    As oilfields are ageing and depleting, operators are forced to start searching for oil in more hostile environments. These new environments can introduce new drilling challenges. Prospects like ultra deep water reservoirs and depleted offshore reservoirs are difficult to drill with conventional drilling. This has lead the industry to developing the Dual Gradient Drilling (DGD) system. DGD is an unconventional drilling method and it is classified as a Managed Pressure Drilling ...

  14. Curvature Gradient Driving Droplets in Fast Motion

    CERN Document Server

    Lv, Cunjing; Yin, Yajun; Tseng, Fan-gang; Zheng, Quanshui

    2011-01-01

    Earlier works found out spontaneous directional motion of liquid droplets on hydrophilic conical surfaces, however, not hydrophobic case. Here we show that droplets on any surface may take place spontaneous directional motion without considering contact angle property. The driving force is found to be proportional to the curvature gradient of the surface. Fast motion can be lead at surfaces with small curvature radii. The above discovery can help to create more effective transportation technology of droplets, and better understand some observed natural phenomena.

  15. Aberrations of Gradient-Index Lenses.

    Science.gov (United States)

    Matthews, A. L.

    Available from UMI in association with The British Library. In this thesis, the primary aberrations of lenses with a radial focussing gradient-of-index are analysed. Such a lens has a refractive index profile which decreases continuously and radially outward from the optical axis, so that the surfaces of constant refractive index are circular cylinders which are coaxial with the optical axis. Current applications of these lenses include photocopiers, medical endoscopes, telecommunications systems and compact disc systems. Closed formulae for the primary wavefront aberrations for a gradient-index lens with curved or plane entry and exit faces are obtained from the differential equations of such a lens to assess the primary transverse ray aberrations that it introduces. Identical expressions are then obtained by using the difference in optical path length produced between two rays by the lens. This duplication of the derivations of the primary wavefront aberrations acts as a confirmation of the validity of the expressions. One advantage of these equations is that the contributions due to the primary spherical aberration, coma, astigmatism, field curvature and distortion can be assessed individually. A Fortran 77 program has been written to calculate each of these individual contributions, the total primary wavefront aberrations and the primary transverse ray aberrations. Further confirmation of the validity of the expressions is obtained by using this program to show that the coma and distortion were both zero for fully symmetric systems working at unit magnification. The program is then used to assess the primary wavefront aberrations for a gradient-index lens which is currently of interest to the telecommunications industry. These results are compared with values obtained using a finite ray-tracing program for the total wavefront aberrations. This shows that the primary wavefront aberrations are the completely dominant contribution to the total wavefront

  16. Broadband mode conversion via gradient index metamaterials

    CERN Document Server

    Wang, HaiXiao; Genevet, Patrice; Jiang, Jian-Hua; Chen, HuanYang

    2015-01-01

    We propose a design for broadband waveguide mode conversion based on gradient index metamaterials (GIMs). Numerical simulations demonstrate that the zeroth order of transverse magnetic mode or the first order of transverse electric mode (TM0/TE1) can be converted into the first order of transverse magnetic mode or the second order of transverse electric mode (TM1/TE2) for a broadband of frequencies. As an application, an asymmetric propagation is achieved by integrating zero index metamaterials inside the GIM waveguide.

  17. Magnetoresponsive Photonic Microspheres with Structural Color Gradient.

    Science.gov (United States)

    Lee, Seung Yeol; Choi, Jongkook; Jeong, Jong-Ryul; Shin, Jung H; Kim, Shin-Hyun

    2017-02-06

    Photonic Janus particles are created by alternately sputtering silica and titania on microspheres in order to obtain a structural color gradient. In addition, the microspheres are rendered magnetoresponsive. The Janus microspheres with optical and magnetic anisotropy enable on-demand control over orientation and structural color through manipulation of an external magnetic field, thereby being useful as active color pigments for reflection-mode displays.

  18. Fixed-Field Alternating-Gradient Accelerators

    CERN Document Server

    Sheehy, S L

    2016-01-01

    These notes provide an overview of Fixed-Field Alternating-Gradient (FFAG) accelerators for medical applications. We begin with a review of the basic principles of this type of accelerator, including the scaling and non-scaling types, highlighting beam dynamics issues that are of relevance to hadron ac- celerators. The potential of FFAG accelerators in the field of hadron therapy is discussed in detail, including an overview of existing medical FFAG designs. The options for FFAG treatment gantries are also considered.

  19. Discontinuous gradient constraints and the infinity Laplacian

    CERN Document Server

    Juutinen, Petri; Rossi, Julio D

    2012-01-01

    Motivated by tug-of-war games and asymptotic analysis of certain variational problems, we consider a gradient constraint problem involving the infinity Laplace operator. We prove that this problem always has a solution that is unique if a certain regularity condition on the constraint is satisfied. If this regularity condition fails, then solutions obtained from game theory and $L^p$-approximation need not coincide.

  20. Gradient Domain Mesh Deformation - A Survey

    Institute of Scientific and Technical Information of China (English)

    Wei-Wei Xu; Kun Zhou

    2009-01-01

    This survey reviews the recent development of gradient domain mesh deformation method. Different to other deformation methods, the gradient domain deformation method is a surface-based, variational optimization method. It directly encodes the geometric details in differential coordinates, which are also called Laplacian coordinates in literature. By preserving the Laplacian coordinates, the mesh details can be well preserved during deformation. Due to the locality of the Laplacian coordinates, the variational optimization problem can be casted into a sparse linear system. Fast sparse linear solver can be adopted to generate deformation result interactively, or even in real-time. The nonlinear nature of gradient domain mesh deformation leads to the development of two categories of deformation methods: linearization methods and nonlinear optimization methods. Basically, the linearization methods only need to solve the linear least-squares system once. They are fast, easy to understand and control, while the deformation result might be suboptimal. Nonlinear optimization methods can reach optimal solution of deformation energy function by iterative updating. Since the computation of nonlinear methods is expensive, reduced deformable models should be adopted to achieve interactive performance. The nonlinear optimization methods avoid the user burden to input transformation at deformation handles, and they can be extended to incorporate various nonlinear constraints, like volume constraint, skeleton constraint, and so on. We review representative methods and related approaches of each category comparatively and hope to help the user understand the motivation behind the algorithms. Finally, we discuss the relation between physical simulation and gradient domain mesh deformation to reveal why it can achieve physically plausible deformation result.