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Sample records for two-step lipase catalysis

  1. Beauveria bassiana Lipase A expressed in Komagataella (Pichia pastoris with potential for biodiesel catalysis

    Directory of Open Access Journals (Sweden)

    Ana Claudia Vici

    2015-10-01

    Full Text Available Lipases (EC 3.1.1.3 comprise a biotechnologically important group of enzymes because they are able to catalyze both hydrolysis and synthesis reactions, depending on the amount of water in the system. One of the most interesting application of lipase is in the biofuel industry for biodiesel production by oil and ethanol (or methanol transesterification. Entomopathogenic fungi, which are potential source of lipases, are still poorly explored in biotechnological processes. The present work reports the heterologous expression and biochemical characterization of a novel Beauveria bassiana lipase with potential for biodiesel production. The His-tagged B. bassiana lipase A (BbLA was produced in Komagataella pastoris in Buffered Methanol Medium (BMM induced with 1% methanol at 30 °C. Purified BbLA was activated with 0.05% Triton X-100 and presented optimum activity at pH 6.0 and 50°C. N-glycosylation of the recombinant BbLA accounts for 31.5% of its molecular weight. Circular dichroism and molecular modeling confirmed a structure composed of α-helix and β-sheet, similar to α/β hydrolases. Immobilized BbLA was able to promote transesterification reactions in fish oil, demonstrating potential for biodiesel production. BbLA was successfully produced in Komagataella pastoris and shows potential use for biodiesel production by the ethanolysis reaction.

  2. Beauveria bassiana Lipase A expressed in Komagataella (Pichia) pastoris with potential for biodiesel catalysis.

    Science.gov (United States)

    Vici, Ana C; da Cruz, Andrezza F; Facchini, Fernanda D A; de Carvalho, Caio C; Pereira, Marita G; Fonseca-Maldonado, Raquel; Ward, Richard J; Pessela, Benevides C; Fernandez-Lorente, Gloria; Torres, Fernando A G; Jorge, João A; Polizeli, Maria L T M

    2015-01-01

    Lipases (EC 3.1.1.3) comprise a biotechnologically important group of enzymes because they are able to catalyze both hydrolysis and synthesis reactions, depending on the amount of water in the system. One of the most interesting applications of lipase is in the biofuel industry for biodiesel production by oil and ethanol (or methanol) transesterification. Entomopathogenic fungi, which are potential source of lipases, are still poorly explored in biotechnological processes. The present work reports the heterologous expression and biochemical characterization of a novel Beauveria bassiana lipase with potential for biodiesel production. The His-tagged B. bassiana lipase A (BbLA) was produced in Komagataella pastoris in buffered methanol medium (BMM) induced with 1% methanol at 30°C. Purified BbLA was activated with 0.05% Triton X-100 and presented optimum activity at pH 6.0 and 50°C. N-glycosylation of the recombinant BbLA accounts for 31.5% of its molecular weight. Circular dichroism and molecular modeling confirmed a structure composed of α-helix and β-sheet, similar to α/β hydrolases. Immobilized BbLA was able to promote transesterification reactions in fish oil, demonstrating potential for biodiesel production. BbLA was successfully produced in K. pastoris and shows potential use for biodiesel production by the ethanolysis reaction.

  3. From Structure to Catalysis: Recent Developments in the Biotechnological Applications of Lipases

    Directory of Open Access Journals (Sweden)

    Cristiane D. Anobom

    2014-01-01

    Full Text Available Microbial lipases are highly appreciated as biocatalysts due to their peculiar characteristics such as the ability to utilize a wide range of substrates, high activity and stability in organic solvents, and regio- and/or enantioselectivity. These enzymes are currently being applied in a variety of biotechnological processes, including detergent preparation, cosmetics and paper production, food processing, biodiesel and biopolymer synthesis, and the biocatalytic resolution of pharmaceutical derivatives, esters, and amino acids. However, in certain segments of industry, the use of lipases is still limited by their high cost. Thus, there is a great interest in obtaining low-cost, highly active, and stable lipases that can be applied in several different industrial branches. Currently, the design of specific enzymes for each type of process has been used as an important tool to address the limitations of natural enzymes. Nowadays, it is possible to “order” a “customized” enzyme that has ideal properties for the development of the desired bioprocess. This review aims to compile recent advances in the biotechnological application of lipases focusing on various methods of enzyme improvement, such as protein engineering (directed evolution and rational design, as well as the use of structural data for rational modification of lipases in order to create higher active and selective biocatalysts.

  4. Cyclic resolution of racemic ibuprofen via coupled efficient lipase and acid-base catalysis.

    Science.gov (United States)

    Liu, Ying; Wang, Fang; Tan, Tianwei

    2009-03-01

    Extracellular lipase LIP prepared in our lab from the yeast Yarrowia lipolytica was used for the resolution of racemic ibuprofen. The (S)-enantiomer was preferred by lipase LIP, and the unreacted (R)-enantiomer was extracted and racemized in basic solvent-water medium to be re-resolved. Solvent, content of solvent, base concentration, and temperature have a strong effect on racemization. The (S)-ester was separated and hydrolyzed to (S)-ibuprofen in acidic dimethyl sulfoxide-water mixture containing 70% dimethyl sulfoxide. The high purity (S)-ibuprofen (ee = 0.98) was obtained using lipase LIP to catalyze hydrolysis of (S)-ester in 0.1 M phosphate buffer (pH = 8). (c) 2008 Wiley-Liss, Inc.

  5. Synthesis of enantiopure drugs and drug intermediates by immobilized lipase-catalysis

    Czech Academy of Sciences Publication Activity Database

    Brabcová, Jana; Filice, M.; Gutarra, M.; Palomo, J. M.

    2013-01-01

    Roč. 9, č. 2 (2013), s. 113-136 ISSN 1573-4072 Grant - others:AV ČR(CZ) M200551203 Institutional support: RVO:61388963 Keywords : lipases * kinetic resolution * asymmetric transformation * chemical modification * immobilization * pharmaceuticals * carbohydrates Subject RIV: CC - Organic Chemistry

  6. Suppression of water as a nucleophile in Candida antarctica lipase B catalysis

    DEFF Research Database (Denmark)

    Larsen, Marianne Wittrup; Zielinska, Dorota F; Martinelle, Mats

    2010-01-01

    A water tunnel in Candida antarctica lipase B that provides the active site with substrate water is hypothesized. A small, focused library created in order to prevent water from entering the active site through the tunnel was screened for increased transacylation over hydrolysis activity. A single...

  7. Preparation of detergent-lipase complexes utilizing water-soluble amphiphiles in single aqueous phase and catalysis of transesterifications in homogeneous organic solvents.

    Science.gov (United States)

    Mine, Y; Fukunaga, K; Maruoka, N; Nakao, K; Sugimura, Y

    2000-01-01

    A novel method of preparing detergent-enzyme complexes that can be employed in organic media was developed utilizing newly synthesized water-soluble nonionic gemini-type detergents, N,N-bis(3-D-gluconamidopropyl)-3-(dialkyl-L-glutamatecarbonyl)propanamides (BIG2CnCA: n = 10,12,14,16,18) and N,N-bis(3-D-lactonamidopropyl)-3-(dialkyl-L-glutamatecarbonyl)propanamides (BIL2CnCA: n = 16,18), and nonionic twin-headed detergents, N,N-bis(3-D-gluconamidopropyl)alkanamides (BIG1Cn: n = 12,14,16,18,delta9). This method simply entails mixing a selected enzyme with an appropriate detergent in an aqueous solution followed by lyophilization, and it offers the advantages of enhanced enzymatic activity in organic solvents and eliminates both enzyme loss and the necessity for an organic solvent in the preparation stage. Using various modified lipases originating from Aspergillus niger (Lipase A), Candida rugosa (Lipase C), Pseudomonas cepacia (Lipase P), and porcine pancreas (PPL), prepared using the novel method and detergents, including conventional synthesized nonionic detergents such as dialkyl N-D-glucona-L-glutamates (2CnGE: n = 12,18delta9) and octanoyl-N-methylglucamide (MEGA-8), enantioselective transesterifications of 6-methyl-5-hepten-2-ol (sulcatol) and 2,2-dimethyl-1,3-dioxolane-4-methanol (solketal) with a vinyl or isopropenyl carboxylate were carried out in an organic solvent. The modified lipase activity was influenced by both the lipases and the structure of the detergents. The value for the hydrophile-lipophile balance (HLB) of the detergent provided a means of correlating the structure and the obtained modified lipase activity. For detergents of the same class with a HLB value of approximately 9 and 12, the highest activity was obtained for Lipase A and Lipase P, and Lipase C and PPL, respectively. Among detergents of the same HLB value tested, the gemini-type detergents possessing the most bulky head and tail were most effective as a modifier for lipases of all

  8. Enhanced catalysis and enantioselective resolution of racemic naproxen methyl ester by lipase encapsulated within iron oxide nanoparticles coated with calix[8]arene valeric acid complexes.

    Science.gov (United States)

    Sayin, Serkan; Akoz, Enise; Yilmaz, Mustafa

    2014-09-14

    In this study, two types of nanoparticles have been used as additives for the encapsulation of Candida rugosa lipase via the sol-gel method. In one case, the nanoparticles were covalently linked with a new synthesized calix[8]arene octa valeric acid derivative (C[8]-C4-COOH) to produce new calix[8]arene-adorned magnetite nanoparticles (NP-C[8]-C4-COOH), and then NP-C[8]-C4-COOH was used as an additive in the sol-gel encapsulation process. In the other case, iron oxide nanoparticles were directly added into the sol-gel encapsulation process in order to interact electrostatically with both C[8]-C4-COOH and Candida rugosa lipase. The catalytic activities and enantioselectivities of two novel encapsulated lipases (Enc-NP-C[8]-C4-COOH and Enc-C[8]-C4-COOH@Fe3O4) in the hydrolysis reaction of racemic naproxen methyl ester were evaluated. The results showed that the activity and enantioselectivity of the lipase were improved when the lipase was encapsulated in the presence of calixarene-based additives. Indeed, the encapsulated lipases have an excellent rate of enantioselectivity, with E = 371 and 265, respectively, as compared to the free enzyme (E = 137). The lipases encapsulated with C[8]-C4-COOH and iron oxide nanoparticles (Enc-C[8]-C4-COOH@Fe3O4) retained more than 86% of their initial activities after 5 repeated uses and 92% with NP-C[8]-C4-COOH.

  9. Two-step chemical decontamination technology

    International Nuclear Information System (INIS)

    Rankin, W.N.

    1992-01-01

    An improved two-step chemical decontamination technique was recently developed at INEL. This memorandum documents the addition of this technology to the SRTC arsenal of decontamination technology. A two-step process using NAOH, KMnO 4 followed by HNO 3 was used for cleaning doorstops (small casks) in the SRTC High Level Caves in 1967. Subsequently, more aggressive chemical techniques have been found to be much more effective for our applications. No further work on two-step technology is planned

  10. Production of Biodiesel from Acid Oil via a Two-Step Enzymatic Transesterification.

    Science.gov (United States)

    Choi, Nakyung; Lee, Jeom-Sig; Kwak, Jieun; Lee, Junsoo; Kim, In-Hwan

    2016-11-01

    A two-step enzymatic transesterification process in a solvent-free system has been developed as a novel approach to the production of biodiesel using acid oil from rice bran oil soapstock. The acid oil consisted of 53.7 wt% fatty acids, 2.4 wt% monoacylglycerols, 9.1 wt% diacylglycerols, 28.8 wt% triacylglycerols, and 6.0 wt% others. Three immobilized lipases were evaluated as potential biocatalysts, including Novozym 435 from Candida antarctica, Lipozyme RM IM from Rhizomucor miehei, and Lipozyme TL IM from Thermomyces lanuginosus. The effects of molar ratio of acid oil to ethanol, temperature, and enzyme loading were investigated to determine the optimum conditions for the transesterification with the three immobilized lipases. The optimum conditions of the three immobilized lipases were a molar ratio of 1:5 (acid oil to ethanol), the temperature range of 30-40°C, and the enzyme loading range of 5-10%. The two-step transesterification was then conducted under the optimum conditions of each lipase. The stepwise use of Novozym 435 and Lipozyme TL IM or Lipozyme RM IM and Lipozyme TL IM resulted in similar or higher levels of yield to the individual lipases. The maximum yields obtained in both stepwise uses were ca. 92%.

  11. Two steps sintering alumina doped with niobia

    International Nuclear Information System (INIS)

    Gomes, L.B.; Hatzfeld, J.; Heck, M.; Pokorny, A.; Bergmann, C.P.

    2014-01-01

    In this work, high surface area commercial alumina was doped with niobia and sintered in two steps in order to obtain dense materials with lower processing temperatures. The powders were milled and uniaxially pressed (200 MPa). The first step of sintering took place at 1100°C for 3, 6, 9 and 12 hours, followed by the second step at 1350°C for 3 hours. The relative density, porosity and water absorption of the samples were determined by the Archimedes method. The crystalline phases were analyzed by X-ray Diffraction (XRD) and the morphology of the samples after sintering, evaluated by Scanning Electron Microscopy (SEM). The results indicate that the use of niobia combined with the two steps sintering promotes an increase in the density of the material, even at lower sintering temperatures. (author)

  12. Railgun-type two step accelerator

    International Nuclear Information System (INIS)

    Kasai, Satoshi; Maeda, Hikosuke; Onozuka, Masanori; Oda, Yasutsugu; Azuma, Kingo.

    1995-01-01

    In the two step-type railgun accelerator used in an experimental nuclear fusion device of the present invention, energy of laser beams to be irradiated in an acceleration gas behind a flying object can be reduced, and the voltage applied between the rails can be lowered. Charged particles are generated and supplied to the acceleration gas behind the flying object by a charged particle generating and supplying device so as to promote generation of plasmas caused by irradiation of laser beams. As a result, dielectric break down is caused between the rails by a Paschen's law by application of voltage lower than dielectric breakdown voltage, thereby enabling to generate plasmas easily. Accordingly, the energy of laser beams can be suppressed and the voltage applied between the rails can be lowered. (I.S.)

  13. Railgun-type two step accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Kasai, Satoshi; Maeda, Hikosuke [Japan Atomic Energy Research Inst., Tokyo (Japan); Onozuka, Masanori; Oda, Yasutsugu; Azuma, Kingo

    1995-10-13

    In the two step-type railgun accelerator used in an experimental nuclear fusion device of the present invention, energy of laser beams to be irradiated in an acceleration gas behind a flying object can be reduced, and the voltage applied between the rails can be lowered. Charged particles are generated and supplied to the acceleration gas behind the flying object by a charged particle generating and supplying device so as to promote generation of plasmas caused by irradiation of laser beams. As a result, dielectric break down is caused between the rails by a Paschen`s law by application of voltage lower than dielectric breakdown voltage, thereby enabling to generate plasmas easily. Accordingly, the energy of laser beams can be suppressed and the voltage applied between the rails can be lowered. (I.S.).

  14. Bacterial lipases

    NARCIS (Netherlands)

    Jaeger, Karl-Erich; Ransac, Stéphane; Dijkstra, Bauke W.; Colson, Charles; Heuvel, Margreet van; Misset, Onno

    Many different bacterial species produce lipases which hydrolyze esters of glycerol with preferably long-chain fatty acids. They act at the interface generated by a hydrophobic lipid substrate in a hydrophilic aqueous medium. A characteristic property of lipases is called interfacial activation,

  15. Uncertainty Principles on Two Step Nilpotent Lie Groups

    Indian Academy of Sciences (India)

    Abstract. We extend an uncertainty principle due to Cowling and Price to two step nilpotent Lie groups, which generalizes a classical theorem of Hardy. We also prove an analogue of Heisenberg inequality on two step nilpotent Lie groups.

  16. Novel Lipases: Expression and Improvement for Applied Biocatalysis = Nuevas lipasas: expresión y mejoras para biocatálisis aplicada

    OpenAIRE

    Infanzón Ramos, Belén

    2017-01-01

    This thesis is focused in the identification and improvement of lipases for biotechnological application. The importance of lipases is increasing in several industries. However, the commercial use of lipases is still a drawback in the economics of the lipase-based industrial applications. There are many tools for improving and adapting the enzyme properties to the desired requirements of a process that could lead lipase catalysis through a cost-effective process. In this context, the main obj...

  17. Novel Lipases: Expression and Improvement for Applied Biocatalysis = Nuevas lipasas: expresión y mejoras para biocatálisis aplicadatalysi Novel Lipases: Expression and Improvement for Applied Biocatalysis = Nuevas lipasas: expresión y mejoras para biocatálisis aplicada

    OpenAIRE

    Infanzón Ramos, Belén

    2017-01-01

    [eng] This thesis is focused in the identification and improvement of lipases for biotechnological application. The importance of lipases is increasing in several industries. However, the commercial use of lipases is still a drawback in the economics of the lipase-based industrial applications. There are many tools for improving and adapting the enzyme properties to the desired requirements of a process that could lead lipase catalysis through a cost-effective process. In this context, the m...

  18. Reduction of NOx in synthetic diesel exhaust via two-step plasma-catalysis treatment

    International Nuclear Information System (INIS)

    Tonkyn, R.G.; Barlow, S.E.; Hoard, John W.

    2003-01-01

    Significant reduction of NO x in synthetic light duty diesel exhaust has been achieved over a broad temperature window by combining atmospheric plasma with appropriate catalysts. The technique relies on the addition of hydrocarbon reductant prior to passing the simulated exhaust through a non-thermal plasma and a catalyst bed. The observed chemistry in the plasma includes conversion of NO to NO 2 as well as the partial oxidation of the hydrocarbon. The overall NO x reduction has a maximum of less than 80%, with this maximum obtained only at high-energy input into the plasma, high concentration of hydrocarbon reductant and low space velocity. We present data in this paper illustrating that a multiple-step treatment strategy, whereby two or more plasma-catalyst reactors are utilized in series, can increase the maximum NO x conversion obtainable. Alternatively, this technique can reduce the energy and/or hydrocarbon requirements for a fixed conversion efficiency. When propene is used as the reductant, the limiting reagent for the overall process is most likely acetaldehyde. The data suggest that acetaldehyde is formed in concert with NO oxidation to NO 2 in the plasma stage. The limited NO x reduction efficiency attained in a single step, even with excess energy, oxygen content and/or hydrocarbon-to-NO x ratio is well explained by this hypothesis, as is the effectiveness of the multiple-step treatment strategy. We present the data here illustrating the advantage of this approach under a wide variety of conditions

  19. Two naturally occurring mutations at the first and second bases of codon aspartic acid 156 in the proposed catalytic triad of human lipoprotein lipase. In vivo evidence that aspartic acid 156 is essential for catalysis

    NARCIS (Netherlands)

    Ma, Y. H.; Bruin, T.; Tuzgol, S.; Wilson, B. I.; Roederer, G.; Liu, M. S.; Davignon, J.; Kastelein, J. J.; Brunzell, J. D.; Hayden, M. R.

    1992-01-01

    We are studying naturally occurring mutations in the gene for lipoprotein lipase (LPL) to advance our knowledge about the structure/function relationships for this enzyme. We and others have previously described 11 mutations in human LPL gene and until now none of these directly involves any of the

  20. Two-Step Plasma Process for Cleaning Indium Bonding Bumps

    Science.gov (United States)

    Greer, Harold F.; Vasquez, Richard P.; Jones, Todd J.; Hoenk, Michael E.; Dickie, Matthew R.; Nikzad, Shouleh

    2009-01-01

    A two-step plasma process has been developed as a means of removing surface oxide layers from indium bumps used in flip-chip hybridization (bump bonding) of integrated circuits. The two-step plasma process makes it possible to remove surface indium oxide, without incurring the adverse effects of the acid etching process.

  1. Two Step Wittig/Dihydroxylation Synthetic Route to Higher Sugars

    DEFF Research Database (Denmark)

    Jørgensen, Morten; Madsen, Robert

    1999-01-01

    Higher carbon sugars are obtained by a two carbon, two step chain elongation of aldoses involving first a Wittig reaction and then an osmium tetroxide catalyzed dihydroxylation......Higher carbon sugars are obtained by a two carbon, two step chain elongation of aldoses involving first a Wittig reaction and then an osmium tetroxide catalyzed dihydroxylation...

  2. Chemical catalysis in biodiesel production (I): enzymatic catalysis processes

    International Nuclear Information System (INIS)

    Jachmarian, I.; Dobroyan, M.; Veira, J.; Vieitez, I.; Mottini, M.; Segura, N.; Grompone, M.

    2009-01-01

    There are some well known advantages related with the substitution of chemical catalysis by enzymatic catalysis processes.Some commercial immobilized lipases are useful for the catalysis of bio diesel reaction, which permits the achievement of high conversions and the recovery of high purity products, like a high quality glycerine. The main disadvantage of this alternative method is related with the last inactivation of the enzyme (by both the effect of the alcohol and the absorption of glycerol on catalyst surface), which added to the high cost of the catalyst, produces an unfavourable economical balance of the entire process. In the work the efficiency of two commercial immobilized lipases (Lipozyme TL IM y Novozyme 435 NNovozymes-Dinamarca) in the catalysis of the continuous transesterification of sunflower oil with different alcohols was studied. The intersolubility of the different mixturesinvolving reactans (S oil/alkyl esters/alcohol) and products (P mixtures with a higher content of 1% of glycerol,while for ethanol homogeneous mixtures were obtained at 12% of glycerol (44.44 12).Using and ethanolic substrate at the proportion S=19:75:6 and Lipozyme TL IM, it was possible to achieve a 98% of convertion to the corresponding biodiesel.When Novozymes 435 catalyzed the process it was possible to increase the oil concentration in the substrateaccording to proportion S=35:30:35, and a 78% conversion was obtained. The productivity shown by the firt enzyme was 70mg biodiesel g enzime-1, hora-1 while with the second one the productivity increased to 230. Results suggested that the convenient adjustement of substrate composition with the addition of biodiesel to reactants offers an efficient method for maximizing the enzyme productivity, hence improving the profitability of the enzymatic catalyzed process. (author)

  3. MIDPOINT TWO- STEPS RULE FOR THE SQUARE ROOT METHOD

    African Journals Online (AJOL)

    DR S.E UWAMUSI

    Aberth third order method for finding zeros of a polynomial in interval ... KEY WORDS: Square root iteration, midpoint two steps Method, ...... A New set of Methods for the simultaneous determination of zeros of polynomial equation and iterative ...

  4. High regioselective acetylation of vitamin A precursors using lipase ...

    African Journals Online (AJOL)

    The effect of different reaction parameters was explored on the acylation of primary hydroxyl group of 1,6-diol by lipase B from Candida antarctica catalysis in organic solvent. First, the effect of the organic solvents was investigated, and the highest conversion rate was obtained in n-hexane. Then, the effect of the acyl donor ...

  5. Environmental catalysis

    International Nuclear Information System (INIS)

    Montes Consuelo; Villa, Aida Luz

    1996-01-01

    The term environmental catalysis has been used lately to refer to a variety of applications of the catalysis, those which, they have grouped in the following categories: a) Control of emissions (chimney Gases and gases of the vehicles, Compound Organic Volatile (VOC), Scents, Chlorofluorocarbons) b) Conversion of having undone solids or liquids. C) Selective obtaining of alternating products that replace polluting compounds. d)replacement of catalysis environmentally dangerous And e)Development of catalysts for the obtaining of valuable chemical products without the formation of polluting by-products. In the group of Environmental Catalysis comes working in the first category, Particularly, in the exploration of active catalysts in the decrease of the emissions coming from combustion systems, carbon monoxide, hydrocarbons, nitrogen oxides (NOx), N20 and sulfur (SOx). Our fundamental premise is that the molecular meshes are catalytic potential for the development of a technology environmentally clean. These materials understand a class of inorganic compound with unique properties and intimately related with the structure. The net of the molecular meshes consists on tetrahedral configuration atoms (Al,Si, P, etc.) united to each other by oxygen atoms. As a result they are not formed three-dimensional structures alone with channels and cavities but also, with openings bounded by rings that consist of a certain number of tetrahedral atoms

  6. Two-Step Incision for Periarterial Sympathectomy of the Hand

    Directory of Open Access Journals (Sweden)

    Seung Bae Jeon

    2015-11-01

    Full Text Available BackgroundSurgical scars on the palmar surface of the hand may lead to functional and also aesthetic and psychological consequences. The objective of this study was to introduce a new incision technique for periarterial sympathectomy of the hand and to compare the results of the new two-step incision technique with those of a Koman incision by using an objective questionnaire.MethodsA total of 40 patients (17 men and 23 women with intractable Raynaud's disease or syndrome underwent surgery in our hospital, conducted by a single surgeon, between January 2008 and January 2013. Patients who had undergone extended sympathectomy or vessel graft were excluded. Clinical evaluation of postoperative scars was performed in both groups one year after surgery using the patient and observer scar assessment scale (POSAS and the Wake Forest University rating scale.ResultsThe total patient score was 8.59 (range, 6-15 in the two-step incision group and 9.62 (range, 7-18 in the Koman incision group. A significant difference was found between the groups in the total PS score (P-value=0.034 but not in the total observer score. Our analysis found no significant difference in preoperative and postoperative Wake Forest University rating scale scores between the two-step and Koman incision groups. The time required for recovery prior to returning to work after surgery was shorter in the two-step incision group, with a mean of 29.48 days in the two-step incision group and 34.15 days in the Koman incision group (P=0.03.ConclusionsCompared to the Koman incision, the new two-step incision technique provides better aesthetic results, similar symptom improvement, and a reduction in the recovery time required before returning to work. Furthermore, this incision allows the surgeon to access a wide surgical field and a sufficient exposure of anatomical structures.

  7. Acid Lipase Disease

    Science.gov (United States)

    ... of Neurological Disorders and Stroke conducts and supports research to understand lipid storage diseases such as acid lipase deficiency and ... of Neurological Disorders and Stroke conducts and supports research to understand lipid storage diseases such as acid lipase deficiency and ...

  8. Two-step rocket engine bipropellant valve concept

    Science.gov (United States)

    Capps, J. E.; Ferguson, R. E.; Pohl, H. O.

    1969-01-01

    Initiating combustion of altitude control rocket engines in a precombustion chamber of ductile material reduces high pressure surges generated by hypergolic propellants. Two-step bipropellant valve concepts control initial propellant flow into precombustion chamber and subsequent full flow into main chamber.

  9. A Two-Step Approach to Analyze Satisfaction Data

    Science.gov (United States)

    Ferrari, Pier Alda; Pagani, Laura; Fiorio, Carlo V.

    2011-01-01

    In this paper a two-step procedure based on Nonlinear Principal Component Analysis (NLPCA) and Multilevel models (MLM) for the analysis of satisfaction data is proposed. The basic hypothesis is that observed ordinal variables describe different aspects of a latent continuous variable, which depends on covariates connected with individual and…

  10. Two-step rapid sulfur capture. Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-04-01

    The primary goal of this program was to test the technical and economic feasibility of a novel dry sorbent injection process called the Two-Step Rapid Sulfur Capture process for several advanced coal utilization systems. The Two-Step Rapid Sulfur Capture process consists of limestone activation in a high temperature auxiliary burner for short times followed by sorbent quenching in a lower temperature sulfur containing coal combustion gas. The Two-Step Rapid Sulfur Capture process is based on the Non-Equilibrium Sulfur Capture process developed by the Energy Technology Office of Textron Defense Systems (ETO/TDS). Based on the Non-Equilibrium Sulfur Capture studies the range of conditions for optimum sorbent activation were thought to be: activation temperature > 2,200 K for activation times in the range of 10--30 ms. Therefore, the aim of the Two-Step process is to create a very active sorbent (under conditions similar to the bomb reactor) and complete the sulfur reaction under thermodynamically favorable conditions. A flow facility was designed and assembled to simulate the temperature, time, stoichiometry, and sulfur gas concentration prevalent in the advanced coal utilization systems such as gasifiers, fluidized bed combustors, mixed-metal oxide desulfurization systems, diesel engines, and gas turbines.

  11. Two-Step Macrocycle Synthesis by Classical Ugi Reaction

    NARCIS (Netherlands)

    Abdelraheem, Eman M M; Khaksar, Samad; Kurpiewska, Katarzyna; Kalinowska-Tłuścik, Justyna; Shaabani, Shabnam; Dömling, Alexander

    2018-01-01

    The direct nonpeptidic macrocycle synthesis of α-isocyano-ω-amines via the classical Ugi four-component reaction (U-4CR) is introduced. Herein an efficient and flexible two-step procedure to complex macrocycles is reported. In the first step, the reaction between unprotected diamines and

  12. Two step culture for production of recombinant herpes simplex virus ...

    African Journals Online (AJOL)

    Herpes simplex virus type 2 (HSV-2) was the major cause of genital herpes in humans. The HSV-2 glycoprotein D (gD2) had been proved to be a potentially effective vaccine for treatment of genital herpes. The present study was to develop a two step culture to express the recombinant gD2 protein using the immobilized ...

  13. Catalysis studies

    International Nuclear Information System (INIS)

    Taylor, T.N.; Ellis, W.P.

    1977-11-01

    The New Research Initiatives Program (NRIP) project on catalysis in Los Alamos Scientific Laboratory (LASL) Group CMB-8 has made significant progress towards performing the first basic in situ experimental studies of heterogeneous catalysis on solid compound surfaces in a LEED-Auger system. To further understand the surface crystallography of a possible catalyst compound, LEED-Auger measurements were made on UO 2 (approximately 100) vicinal surfaces. These (approximately 100) vicinal surfaces were shown to decompose irreversibly into lower index facets, including prominent (100) facets, at temperatures below those needed for creation of lowest index faceting on (approximately 111) vicinal surfaces. LEED examination of fully faceted surfaces from both types of UO 2 vicinal cuts did not show evidence of cyclopropane or propene chemisorption. The existing LEED-Auger system was modified to allow catalytic reactions at approximately less than 10 -3 torr. A sample holder, specifically designed for catalysis measurements in the modified system, was tested while examining single crystals of CoO and Cr 2 O 3 . Extensive LEED-Auger measurements were made on CoO in vacuo and in the presence of light hydrocarbons and alcohols plus H 2 O, NO, and NH 3 . No chemisorptive behavior was observed except with H 2 O in the presence of the electron beam. Although only examined briefly, the Cr 2 O 3 was remarkable for the sharp LEED features obtained prior to any surface treatment in the vacuum system

  14. Two-step two-stage fission gas release model

    International Nuclear Information System (INIS)

    Kim, Yong-soo; Lee, Chan-bock

    2006-01-01

    Based on the recent theoretical model, two-step two-stage model is developed which incorporates two stage diffusion processes, grain lattice and grain boundary diffusion, coupled with the two step burn-up factor in the low and high burn-up regime. FRAPCON-3 code and its in-pile data sets have been used for the benchmarking and validation of this model. Results reveals that its prediction is in better agreement with the experimental measurements than that by any model contained in the FRAPCON-3 code such as ANS 5.4, modified ANS5.4, and Forsberg-Massih model over whole burn-up range up to 70,000 MWd/MTU. (author)

  15. Two Step Synthesis of a Non-symmetric Acetylcholinesterase Reactivator

    Directory of Open Access Journals (Sweden)

    Vit Koleckar

    2007-08-01

    Full Text Available The newly developed and very promising acetylcholinesterase reactivator (E-1- (2-hydroxyiminomethylpyridinium-4-(4-hydroxyiminomethylpyridinium-but-2-ene dibromide was prepared using two different pathways via a two-step synthesis involving the appropriate (E-1-(4-bromobut-2-enyl-2- or 4-hydroxyiminomethyl-pyridinium bromides. Afterwards, purities and yields of the desired product prepared by both routes were compared. Finally, its potency to reactivate several nerve agent-inhibited acetylcholinesterases was tested.

  16. Two-step Raman spectroscopy method for tumor diagnosis

    Science.gov (United States)

    Zakharov, V. P.; Bratchenko, I. A.; Kozlov, S. V.; Moryatov, A. A.; Myakinin, O. O.; Artemyev, D. N.

    2014-05-01

    Two-step Raman spectroscopy phase method was proposed for differential diagnosis of malignant tumor in skin and lung tissue. It includes detection of malignant tumor in healthy tissue on first step with identification of concrete cancer type on the second step. Proposed phase method analyze spectral intensity alteration in 1300-1340 and 1640-1680 cm-1 Raman bands in relation to the intensity of the 1450 cm-1 band on first step, and relative differences between RS intensities for tumor area and healthy skin closely adjacent to the lesion on the second step. It was tested more than 40 ex vivo samples of lung tissue and more than 50 in vivo skin tumors. Linear Discriminant Analysis, Quadratic Discriminant Analysis and Support Vector Machine were used for tumors type classification on phase planes. It is shown that two-step phase method allows to reach 88.9% sensitivity and 87.8% specificity for malignant melanoma diagnosis (skin cancer); 100% sensitivity and 81.5% specificity for adenocarcinoma diagnosis (lung cancer); 90.9% sensitivity and 77.8% specificity for squamous cell carcinoma diagnosis (lung cancer).

  17. Lipase-catalyzed ring-opening polymerization of lactones to polyesters and its mechanistic aspects.

    Science.gov (United States)

    Namekawa, S; Suda, S; Uyama, H; Kobayashi, S

    1999-01-01

    Lipase catalysis induced a ring-opening polymerization of lactones with different ring-sizes. Small-size (four-membered) and medium-size lactones (six- and seven-membered) as well as macrolides (12-, 13-, 16-, and 17-membered) were subjected to lipase-catalyzed polymerization. The polymerization behaviors depended primarily on the lipase origin and the monomer structure. The macrolides showing much lower anionic polymerizability were enzymatically polymerized faster than epsilon-caprolactone. The granular immobilized lipase derived from Candida antartica showed extremely efficient catalysis in the polymerization of epsilon-caprolactone. Single-step terminal functionalization of the polyester was achieved by initiator and terminator methods. The enzymatic polymerizability of lactones was quantitatively evaluated by Michaelis-Menten kinetics.

  18. Environmental catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Janssen, F.J.J.G.; Santen, R.A. van (eds.)

    1999-04-01

    Catalysts play key roles in the production of clean fuels, the conversion of waste and green raw materials into energy, clean combustion engines including control of NOx and soot production and reduction of greenhouse gases, production of clean water and polymers, as well as reduction from polymers to monometers. This book contains 15 chapters by experts in the field, on the theme of catalysts used to create a sustainable society. Chapters include: catalysts for renewable energy and chemicals, fuel cells, catalytic processes for high-quality transportation fuels; oxidative coupling of methane, methane utilisation via synthesis gas generation, catalytic combustion, catalytical removal of nitrate from water, contribution of catalysis towards the reduction of atmospheric air pollution (CO{sub 2}, CFCs, N{sub 2}O), ozone), emission control from mobile sources and from stationary sources, and deactivation, regeneration and recycling of hydroprocessing catalysts.

  19. Two-step photoionization of hydrogen atoms in interplanetary space

    International Nuclear Information System (INIS)

    Gruntman, M.A.

    1990-01-01

    Photoionization is one of the key processes which determine the properties of fluxes of neutral atoms in interplanetary space. A new two-step channel (called indirect) of photoionization of hydrogen atoms is proposed. Hydrogen atoms are at first excited to states with principal quantum number n > 2, then decay to metastable H(2S) states, where they can be photoionized. Competing processes due to the interaction with solar wind plasma and solar radiation are considered and the photoionization rate through the proposed indirect channel is calculated. This rate depends on distance from the Sun as ∝ 1/R 4 at large distances (R > 1-2 a.u.) and as ∝ 1/R 2 at close approaches, where it is higher than the rate of direct photoionization. (author)

  20. Strong Stability Preserving Two-step Runge–Kutta Methods

    KAUST Repository

    Ketcheson, David I.; Gottlieb, Sigal; Macdonald, Colin B.

    2011-01-01

    We investigate the strong stability preserving (SSP) property of two-step Runge–Kutta (TSRK) methods. We prove that all SSP TSRK methods belong to a particularly simple subclass of TSRK methods, in which stages from the previous step are not used. We derive simple order conditions for this subclass. Whereas explicit SSP Runge–Kutta methods have order at most four, we prove that explicit SSP TSRK methods have order at most eight. We present explicit TSRK methods of up to eighth order that were found by numerical search. These methods have larger SSP coefficients than any known methods of the same order of accuracy and may be implemented in a form with relatively modest storage requirements. The usefulness of the TSRK methods is demonstrated through numerical examples, including integration of very high order weighted essentially non-oscillatory discretizations.

  1. Two-step variable selection in quantile regression models

    Directory of Open Access Journals (Sweden)

    FAN Yali

    2015-06-01

    Full Text Available We propose a two-step variable selection procedure for high dimensional quantile regressions, in which the dimension of the covariates, pn is much larger than the sample size n. In the first step, we perform ℓ1 penalty, and we demonstrate that the first step penalized estimator with the LASSO penalty can reduce the model from an ultra-high dimensional to a model whose size has the same order as that of the true model, and the selected model can cover the true model. The second step excludes the remained irrelevant covariates by applying the adaptive LASSO penalty to the reduced model obtained from the first step. Under some regularity conditions, we show that our procedure enjoys the model selection consistency. We conduct a simulation study and a real data analysis to evaluate the finite sample performance of the proposed approach.

  2. Adiabatic tapered optical fiber fabrication in two step etching

    Science.gov (United States)

    Chenari, Z.; Latifi, H.; Ghamari, S.; Hashemi, R. S.; Doroodmand, F.

    2016-01-01

    A two-step etching method using HF acid and Buffered HF is proposed to fabricate adiabatic biconical optical fiber tapers. Due to the fact that the etching rate in second step is almost 3 times slower than the previous droplet etching method, terminating the fabrication process is controllable enough to achieve a desirable fiber diameter. By monitoring transmitted spectrum, final diameter and adiabaticity of tapers are deduced. Tapers with losses about 0.3 dB in air and 4.2 dB in water are produced. The biconical fiber taper fabricated using this method is used to excite whispering gallery modes (WGMs) on a microsphere surface in an aquatic environment. So that they are suitable to be used in applications like WGM biosensors.

  3. Strong Stability Preserving Two-step Runge–Kutta Methods

    KAUST Repository

    Ketcheson, David I.

    2011-12-22

    We investigate the strong stability preserving (SSP) property of two-step Runge–Kutta (TSRK) methods. We prove that all SSP TSRK methods belong to a particularly simple subclass of TSRK methods, in which stages from the previous step are not used. We derive simple order conditions for this subclass. Whereas explicit SSP Runge–Kutta methods have order at most four, we prove that explicit SSP TSRK methods have order at most eight. We present explicit TSRK methods of up to eighth order that were found by numerical search. These methods have larger SSP coefficients than any known methods of the same order of accuracy and may be implemented in a form with relatively modest storage requirements. The usefulness of the TSRK methods is demonstrated through numerical examples, including integration of very high order weighted essentially non-oscillatory discretizations.

  4. Maximization of Intracellular Lipase Production in a Lipase-Overproducing Mutant Derivative of Rhizopus oligosporus DGM 31: A Kinetic Study

    Directory of Open Access Journals (Sweden)

    Tehreema Iftikhar

    2008-01-01

    Full Text Available Regulation and maximization of lipase production in a mutant derivative of R. oligosporus has been investigated using different substrates, inoculum sizes, pH of the medium, temperature, and nitrogen sources in shake flask experiments and batch fermentation in a fermentor. The production of intracellular lipase was improved 3 times following medium optimization involving one-at-a-time approach and aeration in the fermentor. Interestingly, intracellular lipase was poorly induced by oils, instead its production was induced by sugars, mainly starch, lactose, sucrose, xylose, glucose and glycerol. Dependent variables studied were cell mass, lipase activity, lipase yield, lipase specific and volumetric rate of formation. It was confirmed that lipase production in the derepressed mutant is sufficiently uncoupled from catabolite repression. The results of average specific productivities at various temperatures worked out according to the Arrhenius equation revealed that mutation decreased the magnitude of enthalpy and entropy demand in the inactivation equilibrium during product formation, suggesting that mutation made the metabolic network of the organism thermally more stable. The highest magnitudes of volumetric productivity (QP=490 IU/(L·h and other product attributes of lipase formation occurring on optimized medium in the fermentor are greater than the values reported by other workers. The purified enzyme is monomeric in nature and exhibits stability up to 80 °C and pH=6.0–8.0. Activation energy, enthalpy and entropy of catalysis at 50 °C, and magnitudes of Gibbs free energy for substrate binding, transition state stabilization and melting point indicated that this lipase is highly thermostable.

  5. Familial lipoprotein lipase deficiency

    Science.gov (United States)

    ... lack an enzyme called lipoprotein lipase. Without this enzyme, the body cannot break down fat from digested food. Fat particles called chylomicrons build up in the blood. Risk factors include a family history of lipoprotein lipase deficiency. The condition is usually ...

  6. Dynamics Of Innovation Diffusion With Two Step Decision Process

    Directory of Open Access Journals (Sweden)

    Szymczyk Michał

    2014-02-01

    Full Text Available The paper discusses the dynamics of innovation diffusion among heterogeneous consumers. We assume that customers’ decision making process is divided into two steps: testing the innovation and later potential adopting. Such a model setup is designed to imitate the mobile applications market. An innovation provider, to some extent, can control the innovation diffusion by two parameters: product quality and marketing activity. Using the multi-agent approach we identify factors influencing the saturation level and the speed of innovation adaptation in the artificial population. The results show that the expected level of innovation adoption among customer’s friends and relative product quality and marketing campaign intensity are crucial factors explaining them. It has to be stressed that the product quality is more important for innovation saturation level and marketing campaign has bigger influence on the speed of diffusion. The topology of social network between customers is found important, but within investigated parameter range it has lover impact on innovation diffusion dynamics than the above mentioned factors

  7. Conventional and two step sintering of PZT-PCN ceramics

    Science.gov (United States)

    Keshavarzi, Mostafa; Rahmani, Hooman; Nemati, Ali; Hashemi, Mahdieh

    2018-02-01

    In this study, PZT-PCN ceramic was made via sol-gel seeding method and effects of conventional sintering (CS) as well as two-step sintering (TSS) were investigated on microstructure, phase formation, density, dielectric and piezoelectric properties. First, high quality powder was achieved by seeding method in which the mixture of Co3O4 and Nb2O5 powder was added to the prepared PZT sol to form PZT-PCN gel. After drying and calcination, pyrochlore free PZT-PCN powder was synthesized. Second, CS and TSS were applied to achieve dense ceramic. The optimum temperature used for 2 h of conventional sintering was obtained at 1150 °C; finally, undesired ZrO2 phase formed in CS procedure was removed successfully with TSS procedure and dielectric and piezoelectric properties were improved compared to the CS procedure. The best electrical properties obtained for the sample sintered by TSS in the initial temperature of T 1 = 1200 °C and secondary temperature of T 2 = 1000 °C for 12 h.

  8. Two-Step Amyloid Aggregation: Sequential Lag Phase Intermediates

    Science.gov (United States)

    Castello, Fabio; Paredes, Jose M.; Ruedas-Rama, Maria J.; Martin, Miguel; Roldan, Mar; Casares, Salvador; Orte, Angel

    2017-01-01

    The self-assembly of proteins into fibrillar structures called amyloid fibrils underlies the onset and symptoms of neurodegenerative diseases, such as Alzheimer’s and Parkinson’s. However, the molecular basis and mechanism of amyloid aggregation are not completely understood. For many amyloidogenic proteins, certain oligomeric intermediates that form in the early aggregation phase appear to be the principal cause of cellular toxicity. Recent computational studies have suggested the importance of nonspecific interactions for the initiation of the oligomerization process prior to the structural conversion steps and template seeding, particularly at low protein concentrations. Here, using advanced single-molecule fluorescence spectroscopy and imaging of a model SH3 domain, we obtained direct evidence that nonspecific aggregates are required in a two-step nucleation mechanism of amyloid aggregation. We identified three different oligomeric types according to their sizes and compactness and performed a full mechanistic study that revealed a mandatory rate-limiting conformational conversion step. We also identified the most cytotoxic species, which may be possible targets for inhibiting and preventing amyloid aggregation.

  9. Tardily accelerated neurologic deterioration in two-step thallium intoxication.

    Science.gov (United States)

    Kuroda, Hiroshi; Mukai, Yoshiyuki; Nishiyama, Shuhei; Takeshita, Takayuki; Tateyama, Maki; Takeda, Atsushi; Aoki, Masashi

    2016-12-01

    Thallium intoxication was reported in cases with accidental ingestion, suicide attempt, and criminal adulteration. Reported cases were mostly one-time ingestion, therefore, the clinical course of divisional ingestion has not been fully known. Here, we report a case with two-step thallium intoxication manifesting as tardily accelerated neurologic deterioration. A 16-year-old adolescent was cryptically poisoned with thallium sulfate twice at an interval of 52days. After the first ingestion, neurologic symptoms including visual loss, myalgia, and weakness in legs developed about 40days after the development of acute gastrointestinal symptoms and alopecia. After the second ingestion, neurologic symptoms deteriorated rapidly and severely without gastrointestinal or cutaneous symptoms. Brain magnetic resonance imaging exhibited bilateral optic nerve atrophy. Nerve conduction studies revealed severe peripheral neuropathies in legs. Thallium intoxication was confirmed by an increase in urine thallium egestion. Most of the neurologic manifestations ameliorated in two years, but the visual loss persisted. The source of thallium ingestion was unraveled afterward because a murder suspect in another homicidal assault confessed the forepast adulteration. This discriminating clinical course may be attributable to the cumulative neurotoxicity due to the longer washout-time of thallium in the nervous system than other organs. It is noteworthy that the divisional thallium intoxication may manifest as progressive optic and peripheral neuropathy without gastrointestinal or cutaneous symptoms. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Two step continuous method to synthesize colloidal spheroid gold nanorods.

    Science.gov (United States)

    Chandra, S; Doran, J; McCormack, S J

    2015-12-01

    This research investigated a two-step continuous process to synthesize colloidal suspension of spheroid gold nanorods. In the first step; gold precursor was reduced to seed-like particles in the presence of polyvinylpyrrolidone and ascorbic acid. In continuous second step; silver nitrate and alkaline sodium hydroxide produced various shape and size Au nanoparticles. The shape was manipulated through weight ratio of ascorbic acid to silver nitrate by varying silver nitrate concentration. The specific weight ratio of 1.35-1.75 grew spheroid gold nanorods of aspect ratio ∼1.85 to ∼2.2. Lower weight ratio of 0.5-1.1 formed spherical nanoparticle. The alkaline medium increased the yield of gold nanorods and reduced reaction time at room temperature. The synthesized gold nanorods retained their shape and size in ethanol. The surface plasmon resonance was red shifted by ∼5 nm due to higher refractive index of ethanol than water. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. A Two-Step Resume Information Extraction Algorithm

    Directory of Open Access Journals (Sweden)

    Jie Chen

    2018-01-01

    Full Text Available With the rapid growth of Internet-based recruiting, there are a great number of personal resumes among recruiting systems. To gain more attention from the recruiters, most resumes are written in diverse formats, including varying font size, font colour, and table cells. However, the diversity of format is harmful to data mining, such as resume information extraction, automatic job matching, and candidates ranking. Supervised methods and rule-based methods have been proposed to extract facts from resumes, but they strongly rely on hierarchical structure information and large amounts of labelled data, which are hard to collect in reality. In this paper, we propose a two-step resume information extraction approach. In the first step, raw text of resume is identified as different resume blocks. To achieve the goal, we design a novel feature, Writing Style, to model sentence syntax information. Besides word index and punctuation index, word lexical attribute and prediction results of classifiers are included in Writing Style. In the second step, multiple classifiers are employed to identify different attributes of fact information in resumes. Experimental results on a real-world dataset show that the algorithm is feasible and effective.

  12. Bacterial lipases for biotechnological applications

    NARCIS (Netherlands)

    Jaeger, Karl-Erich; Schneidinger, Bernd; Rosenau, Frank; Werner, Michael; Lang, Dietmar; Dijkstra, Bauke W.; Schimossek, Klaus; Zonta, Albin; Reetz, Manfred T.

    1997-01-01

    Lipase genes originating from the Gram-negative bacteria Serrutiu marcescens and Pseudomonus urruginosa were cloned. S. marcescens lipase was overexpressed in Escherichia coli yielding inclusion bodies which were purified and finally refolded to give enzymatically active lipase. The lipase operon of

  13. Two-step evolution of endosymbiosis between hydra and algae.

    Science.gov (United States)

    Ishikawa, Masakazu; Shimizu, Hiroshi; Nozawa, Masafumi; Ikeo, Kazuho; Gojobori, Takashi

    2016-10-01

    In the Hydra vulgaris group, only 2 of the 25 strains in the collection of the National Institute of Genetics in Japan currently show endosymbiosis with green algae. However, whether the other non-symbiotic strains also have the potential to harbor algae remains unknown. The endosymbiotic potential of non-symbiotic strains that can harbor algae may have been acquired before or during divergence of the strains. With the aim of understanding the evolutionary process of endosymbiosis in the H. vulgaris group, we examined the endosymbiotic potential of non-symbiotic strains of the H. vulgaris group by artificially introducing endosymbiotic algae. We found that 12 of the 23 non-symbiotic strains were able to harbor the algae until reaching the grand-offspring through the asexual reproduction by budding. Moreover, a phylogenetic analysis of mitochondrial genome sequences showed that all the strains with endosymbiotic potential grouped into a single cluster (cluster γ). This cluster contained two strains (J7 and J10) that currently harbor algae; however, these strains were not the closest relatives. These results suggest that evolution of endosymbiosis occurred in two steps; first, endosymbiotic potential was gained once in the ancestor of the cluster γ lineage; second, strains J7 and J10 obtained algae independently after the divergence of the strains. By demonstrating the evolution of the endosymbiotic potential in non-symbiotic H. vulgaris group strains, we have clearly distinguished two evolutionary steps. The step-by-step evolutionary process provides significant insight into the evolution of endosymbiosis in cnidarians. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Two-Step Evolution of Endosymbiosis between Hydra and Algae

    KAUST Repository

    Ishikawa, Masakazu

    2016-07-09

    In the Hydra vulgaris group, only 2 of the 25 strains in the collection of the National Institute of Genetics in Japan currently show endosymbiosis with green algae. However, whether the other non-symbiotic strains also have the potential to harbor algae remains unknown. The endosymbiotic potential of non-symbiotic strains that can harbor algae may have been acquired before or during divergence of the strains. With the aim of understanding the evolutionary process of endosymbiosis in the H. vulgaris group, we examined the endosymbiotic potential of non-symbiotic strains of the H. vulgaris group by artificially introducing endosymbiotic algae. We found that 12 of the 23 non-symbiotic strains were able to harbor the algae until reaching the grand-offspring through the asexual reproduction by budding. Moreover, a phylogenetic analysis of mitochondrial genome sequences showed that all the strains with endosymbiotic potential grouped into a single cluster (cluster γ). This cluster contained two strains (J7 and J10) that currently harbor algae; however, these strains were not the closest relatives. These results suggest that evolution of endosymbiosis occurred in two steps; first, endosymbiotic potential was gained once in the ancestor of the cluster γ lineage; second, strains J7 and J10 obtained algae independently after the divergence of the strains. By demonstrating the evolution of the endosymbiotic potential in non-symbiotic H. vulgaris group strains, we have clearly distinguished two evolutionary steps. The step-by-step evolutionary process provides significant insight into the evolution of endosymbiosis in cnidarians.

  15. Lipase polystyrene giant amphiphiles.

    Science.gov (United States)

    Velonia, Kelly; Rowan, Alan E; Nolte, Roeland J M

    2002-04-24

    A new type of giant amphiphilic molecule has been synthesized by covalently connecting a lipase enzyme headgroup to a maleimide-functionalized polystyrene tail (40 repeat units). The resulting biohybrid forms catalytic micellar rods in water.

  16. Advances in catalysis

    CERN Document Server

    Gates, Bruce C

    2012-01-01

    Advances in Catalysis fills the gap between the journal papers and the textbooks across the diverse areas of catalysis research. For more than 60 years Advances in Catalysis has been dedicated to recording progress in the field of catalysis and providing the scientific community with comprehensive and authoritative reviews. This series in invaluable to chemical engineers, physical chemists, biochemists, researchers and industrial chemists working in the fields of catalysis and materials chemistry. * In-depth, critical, state-of-the-art reviews * Comprehensive, covers of all as

  17. Synthesis of polyurea from 1,6-hexanediamine with CO2 through a two-step polymerization

    Directory of Open Access Journals (Sweden)

    Shan Jiang

    2017-10-01

    Full Text Available Activation and transformation of CO2 is one of the important issues in the field of green and sustainable chemistry. Herein, CO2 as a carbon-oxygen resource was converted to CO2-polyurea with 1,6-hexanediamine through a two-step polymerization. The reaction parameters such as temperature, pressure and reaction time were examined; and several kinds of catalysts were screened in the absence and presence of NMP solvent. The formed oligomer and the final polyurea were characterized by FT-IR, VT-DRIFTS, NMR, XRD, AFM and their thermal properties were examined by TGA and DSC. It was confirmed that the final polyurea has a high thermal stability; the melting temperature is 269 °C and the decomposition temperature is above 300 °C. It is a brittle polymer with a tensile strength of 18.35 MPa at break length of 1.64%. The polyurea has a stronger solvent resistance due to the ordered hydrogen bond in structure. The average molecular weight should be enhanced in the post-polymerization as the appearance, hydrogen bond intensity, crystallinity, melting point and the thermal stability changed largely compared to the oligomer. The present work provides a new kind of polyurea, it is expected to have a wide application in the field of polymer materials. Keywords: CO2, Polyurea, Two-step polymerization, Catalysis

  18. Challenges and perspectives for catalysis in production of diesel from biomass

    DEFF Research Database (Denmark)

    Madsen, Anders Theilgaard; Søndergaard, Helle; Fehrmann, Rasmus

    2011-01-01

    oils or waste fats with methanol is the most prominent and has been applied industrially for a decade. Homogeneous acid and base catalysis is normally used, but solid acids, solid bases, ionic liquids and lipases are being developed as replacements. Hydrodeoxygenation of vegetable oils has likewise...

  19. Multicatalyst system in asymmetric catalysis

    CERN Document Server

    Zhou, Jian

    2014-01-01

    This book introduces multi-catalyst systems by describing their mechanism and advantages in asymmetric catalysis.  Helps organic chemists perform more efficient catalysis with step-by-step methods  Overviews new concepts and progress for greener and economic catalytic reactions  Covers topics of interest in asymmetric catalysis including bifunctional catalysis, cooperative catalysis, multimetallic catalysis, and novel tandem reactions   Has applications for pharmaceuticals, agrochemicals, materials, and flavour and fragrance

  20. Catalysis seen in action

    NARCIS (Netherlands)

    Tromp, M.

    2015-01-01

    Synchrotron radiation techniques are widely applied in materials research and heterogeneous catalysis. In homogeneous catalysis, its use so far is rather limited despite its high potential. Here, insights in the strengths and limitations of X-ray spectroscopy technique in the field of homogeneous

  1. Monopole catalysis: an overview

    International Nuclear Information System (INIS)

    Dawson, S.

    1983-11-01

    A summary of the talks presented in the topological workshop on monopole catalysis at this conference is given. We place special emphasis on the conservation laws which determine the allowed monopole-fermion interactions and on catalysis as a probe of the structure of a grand unified theory. 11 references

  2. Catalysis of Supramolecular Hydrogelation

    NARCIS (Netherlands)

    Trausel, F.; Versluis, F.; Maity, C.; Poolman, J.M.; Lovrak, M.; van Esch, J.H.; Eelkema, R.

    2016-01-01

    ConspectusOne often thinks of catalysts as chemical tools to accelerate a reaction or to have a reaction run under more benign conditions. As such, catalysis has a role to play in the chemical industry and in lab scale synthesis that is not to be underestimated. Still, the role of catalysis in

  3. A simple and accurate two-step long DNA sequences synthesis strategy to improve heterologous gene expression in pichia.

    Directory of Open Access Journals (Sweden)

    Jiang-Ke Yang

    Full Text Available In vitro gene chemical synthesis is a powerful tool to improve the expression of gene in heterologous system. In this study, a two-step gene synthesis strategy that combines an assembly PCR and an overlap extension PCR (AOE was developed. In this strategy, the chemically synthesized oligonucleotides were assembled into several 200-500 bp fragments with 20-25 bp overlap at each end by assembly PCR, and then an overlap extension PCR was conducted to assemble all these fragments into a full length DNA sequence. Using this method, we de novo designed and optimized the codon of Rhizopus oryzae lipase gene ROL (810 bp and Aspergillus niger phytase gene phyA (1404 bp. Compared with the original ROL gene and phyA gene, the codon-optimized genes expressed at a significantly higher level in yeasts after methanol induction. We believe this AOE method to be of special interest as it is simple, accurate and has no limitation with respect to the size of the gene to be synthesized. Combined with de novo design, this method allows the rapid synthesis of a gene optimized for expression in the system of choice and production of sufficient biological material for molecular characterization and biotechnological application.

  4. Calculation of the MSD two-step process with the sudden approximation

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Shiro [Tohoku Univ., Sendai (Japan). Dept. of Physics; Kawano, Toshihiko [Kyushu Univ., Advanced Energy Engineering Science, Kasuga, Fukuoka (Japan)

    2000-03-01

    A calculation of the two-step process with the sudden approximation is described. The Green's function which connects the one-step matrix element to the two-step one is represented in {gamma}-space to avoid the on-energy-shell approximation. Microscopically calculated two-step cross sections are averaged together with an appropriate level density to give a two-step cross section. The calculated cross sections are compared with the experimental data, however the calculation still contains several simplifications at this moment. (author)

  5. Horizons in catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Idol, J D

    1979-04-21

    A discussion covers a brief historical review of industrial catalysis; a survey of major present-day catalytic processes in the petroleum and petrochemical industries; the outlook for the industrial catalyst applications in coal liquefaction, conversion of coal liquids, shale oil, and other synthetic crude sources for transportation fuels, and synthesis gas-based processes; some important directions for future developments, including phase transfer catalysis, photocatalysis, and advanced techniques for catalyst studies; and the need for closer industry-university and industry-government cooperation in the field of catalysis.

  6. Surface and nanomolecular catalysis

    CERN Document Server

    Richards, Ryan

    2006-01-01

    Using new instrumentation and experimental techniques that allow scientists to observe chemical reactions and molecular properties at the nanoscale, the authors of Surface and Nanomolecular Catalysis reveal new insights into the surface chemistry of catalysts and the reaction mechanisms that actually occur at a molecular level during catalysis. While each chapter contains the necessary background and explanations to stand alone, the diverse collection of chapters shows how developments from various fields each contributed to our current understanding of nanomolecular catalysis as a whole. The

  7. Molecular water oxidation catalysis

    CERN Document Server

    Llobet, Antoni

    2014-01-01

    Photocatalytic water splitting is a promising strategy for capturing energy from the sun by coupling light harvesting and the oxidation of water, in order to create clean hydrogen fuel. Thus a deep knowledge of the water oxidation catalysis field is essential to be able to come up with useful energy conversion devices based on sunlight and water splitting. Molecular Water Oxidation Catalysis: A Key Topic for New Sustainable Energy Conversion Schemes presents a comprehensive and state-of-the-art overview of water oxidation catalysis in homogeneous phase, describing in detail the most importan

  8. Ehrenfest's theorem and the validity of the two-step model for strong-field ionization

    DEFF Research Database (Denmark)

    Shvetsov-Shilovskiy, Nikolay; Dimitrovski, Darko; Madsen, Lars Bojer

    By comparison with the solution of the time-dependent Schrodinger equation we explore the validity of the two-step semiclassical model for strong-field ionization in elliptically polarized laser pulses. We find that the discrepancy between the two-step model and the quantum theory correlates...

  9. Process Technology for Immobilized LipaseProcess Technology for Immobilized Lipase-catalyzed

    DEFF Research Database (Denmark)

    Xu, Yuan

    Biocatalysis has attracted significant attention recently, mainly due to its high selectivity and potential benefits for sustainability. Applications can be found in biorefineries, turning biomass into energy and chemicals, and also for products in the food and pharmaceutical industries. However......, most applications remain in the production of high-value fine chemicals, primarily because of the expense of introducing new technology. In particular lipasecatalyzed synthesis has already achieved efficient operations for high-value products and more interesting now is to establish opportunities......-down experimental work is described in this thesis. The methodology uses economic targets to test options characterized via a set of tools. In order to validate the methodology, two processes based on immobilized lipase-catalysis have been studied: transesterification and esterification of vegetable oils...

  10. Application of alkaline thermo-stable lipase(s) enzyme produced from irradiated microbial isolate in the field of detergent technology

    International Nuclear Information System (INIS)

    Ahmed, O.E.A.M.S

    2010-01-01

    . - B. brevis B 2 lipase(s) inhibited by ethylene diamine tetra-acetate indicating the participation of a metal cation in enzyme catalysis. This is supported by the finding that the enzyme was stimulated by Ca 2+ . All other tested metals have high inhibitory effect. - The enzyme was unstable in presence of chlorine and loss its activity after few minutes, while the presence of some surfactants and oxidizing agents enhanced the enzyme activity which reached 3-fold in presence of H 2 O 2 .- The addition of partially purified lipase(s) to commercial detergents resulted in increasing the percentage of detergent catalytic activities. - The wash performing analysis, of crude and purified enzyme used separately or combined with Egyptian detergent (Fol), revealed that the crude and purified enzyme could effectively removed variety of stains such as blood, chocolate, mango, tomato sauce and oil. It is clear from the overall previous results that the possibility of B. brevis B 2 to produce thermoalkalo-stable lipase(s) who cultivated on the cheapest substrates (fish-wastes which cause pollution of the surrounding environment) and use the enzyme as an additive in detergent for a potential application not only in heavy-duty detergents for fabrics but also in bleaches and detergents for automatic dishwashing machines instead of chemical agents.

  11. Performance enhancement of a heterojunction bipolar transistor (HBT) by two-step passivation

    International Nuclear Information System (INIS)

    Fu, S.-I.; Lai, P.-H.; Tsai, Y.-Y.; Hung, C.-W.; Yen, C.-H.; Cheng, S.-Y.; Liu, W.-C.

    2006-01-01

    An interesting two-step passivation (with ledge structure and sulphide based chemical treatment) on base surface, for the first time, is demonstrated to study the temperature-dependent DC characteristics and noise performance of an InGaP/GaAs heterojunction bipolar transistor (HBT). Improved transistor behaviors on maximum current gain β max , offset voltage ΔV CE , and emitter size effect are obtained by using the two-step passivation. Moreover, the device with the two-step passivation exhibits relatively temperature-independent and improved thermal stable performances as the temperature is increased. Therefore, the two-step passivationed device can be used for high-temperature and low-power electronics applications

  12. Investigation to biodiesel production by the two-step homogeneous base-catalyzed transesterification.

    Science.gov (United States)

    Ye, Jianchu; Tu, Song; Sha, Yong

    2010-10-01

    For the two-step transesterification biodiesel production made from the sunflower oil, based on the kinetics model of the homogeneous base-catalyzed transesterification and the liquid-liquid phase equilibrium of the transesterification product, the total methanol/oil mole ratio, the total reaction time, and the split ratios of methanol and reaction time between the two reactors in the stage of the two-step reaction are determined quantitatively. In consideration of the transesterification intermediate product, both the traditional distillation separation process and the improved separation process of the two-step reaction product are investigated in detail by means of the rigorous process simulation. In comparison with the traditional distillation process, the improved separation process of the two-step reaction product has distinct advantage in the energy duty and equipment requirement due to replacement of the costly methanol-biodiesel distillation column. Copyright 2010 Elsevier Ltd. All rights reserved.

  13. Two-step sintering of ultrafine-grained barium cerate proton conducting ceramics

    International Nuclear Information System (INIS)

    Wang, Siwei; Zhang, Lei; Zhang, Lingling; Brinkman, Kyle; Chen, Fanglin

    2013-01-01

    Ultra-fine grained dense BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3−δ (BZCYYb) ceramics have been successfully prepared via a two-step sintering method. Co-precipitation method has been adopted to prepare nano-sized BZCYYb precursors with an average particle size of 30 nm. By controlling the sintering profile, an average grain size of 184 nm was obtained for dense BZCYYb ceramics via the two-step sintering method, compared to 445 nm for the conventional sintered samples. The two-step sintered BZCYYb samples showed less impurity and an enhanced electrical conductivity compared with the conventional sintered ones. Further, the two-step sintering method was applied to fabricate anode supported solid oxide fuel cells (SOFCs) using BZCYYb as the electrolyte, resulting in dense ultrafine-grained electrolyte membranes and porous anode substrates with fine particles. Due to the reduced ohmic as well as polarization resistances, the maximum power output of the cells fabricated from the two-step sintering method reached 349 mW m −2 at 700 °C, significantly improved from 172 mW cm −2 for the conventional sintered cells, suggesting that two-step sintering method is very promising for optimizing the microstructure and thus enhancing the electrochemical performances for barium cerate based proton-conducting SOFCs.

  14. Catalysis seen in action.

    Science.gov (United States)

    Tromp, Moniek

    2015-03-06

    Synchrotron radiation techniques are widely applied in materials research and heterogeneous catalysis. In homogeneous catalysis, its use so far is rather limited despite its high potential. Here, insights in the strengths and limitations of X-ray spectroscopy technique in the field of homogeneous catalysis are given, including new technique developments. A relevant homogeneous catalyst, used in the industrially important selective oligomerization of ethene, is taken as a worked-out example. Emphasis is placed on time-resolved operando X-ray absorption spectroscopy with outlooks to novel high energy resolution and emission techniques. All experiments described have been or can be done at the Diamond Light Source Ltd (Didcot, UK). © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  15. Concepts in catalysis

    International Nuclear Information System (INIS)

    Boudart, M.

    1992-01-01

    This paper reports on concept in catalysis which are very important in heterogeneous catalysis, even today, when in spite of surface science, the complexity of events at a real catalytic surface is still evading the understanding necessary for design. In this paper the authors will attempt to give an update on evolving concepts in heterogeneous catalysis. The topics include: counting active centers on metal surfaces; the notion of turnover frequency for a catalytic cycle; the concept of structure (in) sensitive reactions; the ensemble (geometric) vs. The ligand (electronic) effect following Sachtler's school; the idea of a rate determining step and of a most abundant reactive intermediate; the effect of surface non-uniformity on catalytic kinetics; what makes catalytic cycles turnover

  16. Catalysis induced by radiations

    International Nuclear Information System (INIS)

    Jimenez B, J.; Gonzalez J, J. C.

    2010-01-01

    In Mexico is generated a great quantity of residuals considered as dangerous, for its capacity of corrosion, reactivity, toxicity to the environment, inflammability and biological-infectious potential. It is important to mention that the toxic compounds cannot be discharged to the sewerage systems and much less to the receiving bodies of water. The usual treatment that receives the dangerous residuals is the incineration and the bordering. The incineration is an efficient form of treating the residuals, but it can be dioxins source and benzofurans, being the phenol and chloro phenol the precursors of these compounds. At the present time the radiolytic degradation of organic compounds has been broadly studied, especially the 4-chloro phenol and of same form the photo catalysis of organic compounds. However the combination of both processes, called radio catalysis is barely reported. In this work the results of the experiments realized for to degrade the 4-chloro phenol by means of radio catalysis are reported. (Author)

  17. Catalysis for alternative energy generation

    CERN Document Server

    2012-01-01

    Summarizes recent problems in using catalysts in alternative energy generation and proposes novel solutions  Reconsiders the role of catalysis in alternative energy generation  Contributors include catalysis and alternative energy experts from across the globe

  18. Editorial: Nanoscience makes catalysis greener

    KAUST Repository

    Polshettiwar, Vivek; Basset, Jean-Marie; Astruc, Didier

    2012-01-01

    Green chemistry by nanocatalysis: Catalysis is a strategic field of science because it involves new ways of meeting energy and sustainability challenges. The concept of green chemistry, which makes the science of catalysis even more creative, has

  19. Isotopes in heterogeneous catalysis

    CERN Document Server

    Hargreaves, Justin SJ

    2006-01-01

    The purpose of this book is to review the current, state-of-the-art application of isotopic methods to the field of heterogeneous catalysis. Isotopic studies are arguably the ultimate technique in in situ methods for heterogeneous catalysis. In this review volume, chapters have been contributed by experts in the field and the coverage includes both the application of specific isotopes - Deuterium, Tritium, Carbon-14, Sulfur-35 and Oxygen-18 - as well as isotopic techniques - determination of surface mobility, steady state transient isotope kinetic analysis, and positron emission profiling.

  20. Coupling of Spinosad Fermentation and Separation Process via Two-Step Macroporous Resin Adsorption Method.

    Science.gov (United States)

    Zhao, Fanglong; Zhang, Chuanbo; Yin, Jing; Shen, Yueqi; Lu, Wenyu

    2015-08-01

    In this paper, a two-step resin adsorption technology was investigated for spinosad production and separation as follows: the first step resin addition into the fermentor at early cultivation period to decrease the timely product concentration in the broth; the second step of resin addition was used after fermentation to adsorb and extract the spinosad. Based on this, a two-step macroporous resin adsorption-membrane separation process for spinosad fermentation, separation, and purification was established. Spinosad concentration in 5-L fermentor increased by 14.45 % after adding 50 g/L macroporous at the beginning of fermentation. The established two-step macroporous resin adsorption-membrane separation process got the 95.43 % purity and 87 % yield for spinosad, which were both higher than that of the conventional crystallization of spinosad from aqueous phase that were 93.23 and 79.15 % separately. The two-step macroporous resin adsorption method has not only carried out the coupling of spinosad fermentation and separation but also increased spinosad productivity. In addition, the two-step macroporous resin adsorption-membrane separation process performs better in spinosad yield and purity.

  1. Pollution Control by Catalysis

    DEFF Research Database (Denmark)

    Eriksen, Kim Michael; Fehrmann, Rasmus

    1998-01-01

    The report summarises the results of two years of collaboration supported by INTAS between Department of Chemistry,DTU,DK , IUSTI,Universite de Provence,FR, ICE/HT University 6of Patras,GR, and Boreskov Institute of Catalysis,RU.The project has been concerned with mechanistic studies of deNOx and...

  2. Preface: Catalysis Today

    DEFF Research Database (Denmark)

    Li, Yongdan

    2016-01-01

    This special issue of Catalysis Today with the theme “Sustain-able Energy” results from a great success of the session “Catalytic Technologies Accelerating the Establishment of Sustainable and Clean Energy”, one of the two sessions of the 1st International Symposium on Catalytic Science and Techn...

  3. Smoke regions extraction based on two steps segmentation and motion detection in early fire

    Science.gov (United States)

    Jian, Wenlin; Wu, Kaizhi; Yu, Zirong; Chen, Lijuan

    2018-03-01

    Aiming at the early problems of video-based smoke detection in fire video, this paper proposes a method to extract smoke suspected regions by combining two steps segmentation and motion characteristics. Early smoldering smoke can be seen as gray or gray-white regions. In the first stage, regions of interests (ROIs) with smoke are obtained by using two step segmentation methods. Then, suspected smoke regions are detected by combining the two step segmentation and motion detection. Finally, morphological processing is used for smoke regions extracting. The Otsu algorithm is used as segmentation method and the ViBe algorithm is used to detect the motion of smoke. The proposed method was tested on 6 test videos with smoke. The experimental results show the effectiveness of our proposed method over visual observation.

  4. Preparation of three-dimensional shaped aluminum alloy foam by two-step foaming

    International Nuclear Information System (INIS)

    Shang, J.T.; Xuming, Chu; Deping, He

    2008-01-01

    A novel method, named two-step foaming, was investigated to prepare three-dimensional shaped aluminum alloy foam used in car industry, spaceflight, packaging and related areas. Calculations of thermal decomposition kinetics of titanium hydride showed that there is a considerable amount of hydrogen releasing when the titanium hydride is heated at a relatively high temperature after heated at a lower temperature. The hydrogen mass to sustain aluminum alloy foam, having a high porosity, was also estimated by calculations. Calculations indicated that as-received titanium hydride without any pre-treatment can be used as foaming agents in two-step foaming. The processes of two-step foaming, including preparing precursors and baking, were also studied by experiments. Results showed that, low titanium hydride dispersion temperature, long titanium hydride dispersion time and low precursors porosity are beneficial to prepare three-dimensional shaped aluminum alloy foams with uniform pores

  5. Numerical calculation on a two-step subdiffusion behavior of lateral protein movement in plasma membranes

    Science.gov (United States)

    Sumi, Tomonari; Okumoto, Atsushi; Goto, Hitoshi; Sekino, Hideo

    2017-10-01

    A two-step subdiffusion behavior of lateral movement of transmembrane proteins in plasma membranes has been observed by using single-molecule experiments. A nested double-compartment model where large compartments are divided into several smaller ones has been proposed in order to explain this observation. These compartments are considered to be delimited by membrane-skeleton "fences" and membrane-protein "pickets" bound to the fences. We perform numerical simulations of a master equation using a simple two-dimensional lattice model to investigate the heterogeneous diffusion dynamics behavior of transmembrane proteins within plasma membranes. We show that the experimentally observed two-step subdiffusion process can be described using fence and picket models combined with decreased local diffusivity of transmembrane proteins in the vicinity of the pickets. This allows us to explain the two-step subdiffusion behavior without explicitly introducing nested double compartments.

  6. Association between the gait pattern characteristics of older people and their two-step test scores.

    Science.gov (United States)

    Kobayashi, Yoshiyuki; Ogata, Toru

    2018-04-27

    The Two-Step test is one of three official tests authorized by the Japanese Orthopedic Association to evaluate the risk of locomotive syndrome (a condition of reduced mobility caused by an impairment of the locomotive organs). It has been reported that the Two-Step test score has a good correlation with one's walking ability; however, its association with the gait pattern of older people during normal walking is still unknown. Therefore, this study aims to clarify the associations between the gait patterns of older people observed during normal walking and their Two-Step test scores. We analyzed the whole waveforms obtained from the lower-extremity joint angles and joint moments of 26 older people in various stages of locomotive syndrome using principal component analysis (PCA). The PCA was conducted using a 260 × 2424 input matrix constructed from the participants' time-normalized pelvic and right-lower-limb-joint angles along three axes (ten trials of 26 participants, 101 time points, 4 angles, 3 axes, and 2 variable types per trial). The Pearson product-moment correlation coefficient between the scores of the principal component vectors (PCVs) and the scores of the Two-Step test revealed that only one PCV (PCV 2) among the 61 obtained relevant PCVs is significantly related to the score of the Two-Step test. We therefore concluded that the joint angles and joint moments related to PCV 2-ankle plantar-flexion, ankle plantar-flexor moments during the late stance phase, ranges of motion and moments on the hip, knee, and ankle joints in the sagittal plane during the entire stance phase-are the motions associated with the Two-Step test.

  7. Biodiesel production with immobilized lipase: A review.

    Science.gov (United States)

    Tan, Tianwei; Lu, Jike; Nie, Kaili; Deng, Li; Wang, Fang

    2010-01-01

    Fatty acid alkyl esters, also called biodiesel, are environmentally friendly and show great potential as an alternative liquid fuel. Biodiesel is produced by transesterification of oils or fats with chemical catalysts or lipase. Immobilized lipase as the biocatalyst draws high attention because that process is "greener". This article reviews the current status of biodiesel production with immobilized lipase, including various lipases, immobilization methods, various feedstocks, lipase inactivation caused by short chain alcohols and large scale industrialization. Adsorption is still the most widely employed method for lipase immobilization. There are two kinds of lipase used most frequently especially for large scale industrialization. One is Candida antartica lipase immobilized on acrylic resin, and the other is Candida sp. 99-125 lipase immobilized on inexpensive textile membranes. However, to further reduce the cost of biodiesel production, new immobilization techniques with higher activity and stability still need to be explored. Copyright 2010 Elsevier Inc. All rights reserved.

  8. Study of CdTe quantum dots grown using a two-step annealing method

    Science.gov (United States)

    Sharma, Kriti; Pandey, Praveen K.; Nagpal, Swati; Bhatnagar, P. K.; Mathur, P. C.

    2006-02-01

    High size dispersion, large average radius of quantum dot and low-volume ratio has been a major hurdle in the development of quantum dot based devices. In the present paper, we have grown CdTe quantum dots in a borosilicate glass matrix using a two-step annealing method. Results of optical characterization and the theoretical model of absorption spectra have shown that quantum dots grown using two-step annealing have lower average radius, lesser size dispersion, higher volume ratio and higher decrease in bulk free energy as compared to quantum dots grown conventionally.

  9. The Microwave-assisted Synthesis of Polyethersulfone (PES as A Matrix in Immobilization of Candida antarctica Lipase B (Cal-B

    Directory of Open Access Journals (Sweden)

    Khusna Widhyahrini

    2017-10-01

    How to Cite: Widhyahrini, K., Handayani, N., Wahyuningrum, D., Nurbaiti, S., Radiman, C.L. (2017. The Microwave-assisted Synthesis of Polyethersulfone (PES as A Matrix in Immobilization of Candida antarctica Lipase B (Cal-B. Bulletin of Chemical Reaction Engineering & Catalysis, 12(3: 343-350 (doi:10.9767/bcrec.12.3.774.343-350

  10. Comparative analyses of lipoprotein lipase, hepatic lipase, and endothelial lipase, and their binding properties with known inhibitors.

    Directory of Open Access Journals (Sweden)

    Ziyun Wang

    Full Text Available The triglyceride lipase gene subfamily plays a central role in lipid and lipoprotein metabolism. There are three members of this subfamily: lipoprotein lipase, hepatic lipase, and endothelial lipase. Although these lipases are implicated in the pathophysiology of hyperlipidemia and atherosclerosis, their structures have not been fully solved. In the current study, we established homology models of these three lipases, and carried out analysis of their activity sites. In addition, we investigated the kinetic characteristics for the catalytic residues using a molecular dynamics simulation strategy. To elucidate the molecular interactions and determine potential key residues involved in the binding to lipase inhibitors, we analyzed the binding pockets and binding poses of known inhibitors of the three lipases. We identified the spatial consensus catalytic triad "Ser-Asp-His", a characteristic motif in all three lipases. Furthermore, we found that the spatial characteristics of the binding pockets of the lipase molecules play a key role in ligand recognition, binding poses, and affinities. To the best of our knowledge, this is the first report that systematically builds homology models of all the triglyceride lipase gene subfamily members. Our data provide novel insights into the molecular structures of lipases and their structure-function relationship, and thus provides groundwork for functional probe design towards lipase-based therapeutic inhibitors for the treatment of hyperlipidemia and atherosclerosis.

  11. Xylose Isomerization with Zeolites in a Two-Step Alcohol–Water Process

    DEFF Research Database (Denmark)

    Paniagua, Marta; Shunmugavel, Saravanamurugan; Melián Rodriguez, Mayra

    2015-01-01

    Isomerization of xylose to xylulose was efficiently catalyzed by large-pore zeolites in a two-step methanol–water process that enhanced the product yield significantly. The reaction pathway involves xylose isomerization to xylulose, which, in part, subsequently reacts with methanol to form methyl...

  12. A Two-Step Model for Assessing Relative Interest in E-Books Compared to Print

    Science.gov (United States)

    Knowlton, Steven A.

    2016-01-01

    Librarians often wish to know whether readers in a particular discipline favor e-books or print books. Because print circulation and e-book usage statistics are not directly comparable, it can be hard to determine the relative interest of readers in the two types of books. This study demonstrates a two-step method by which librarians can assess…

  13. Finite cluster renormalization and new two step renormalization group for Ising model

    International Nuclear Information System (INIS)

    Benyoussef, A.; El Kenz, A.

    1989-09-01

    New types of renormalization group theory using the generalized Callen identities are exploited in the study of the Ising model. Another type of two-step renormalization is proposed. Critical couplings and critical exponents y T and y H are calculated by these methods for square and simple cubic lattices, using different size clusters. (author). 17 refs, 2 tabs

  14. The cc-bar and bb-bar spectroscopy in the two-step potential model

    International Nuclear Information System (INIS)

    Kulshreshtha, D.S.; Kaiserslautern Univ.

    1984-07-01

    We investigate the spectroscopy of the charmonium (cc-bar) and bottonium (bb-bar) bound states in a static flavour independent nonrelativistic quark-antiquark (qq-bar) two-step potential model proposed earlier. Our predictions are in good agreement with experimental data and with other theoretical predictions. (author)

  15. Game Theory and Technical Communication: Interpreting the Texas Two-Step through Harsanyi Transformation

    Science.gov (United States)

    Williams, Miriam F.

    2012-01-01

    The author uses game theoretical models to identify technical communication breakdowns encountered during the notoriously confusing Texas Two-Step voting and caucusing process. Specifically, the author uses narrative theory and game theory to highlight areas where caucus participants needed instructions to better understand the rules of the game…

  16. some generalized two-step block hybrid numerov method for solving ...

    African Journals Online (AJOL)

    Nwokem et al.

    ABSTRACT. This paper proposes a class of generalized two-step Numerov methods, a block hybrid type for the direct solution of general second order ordinary differential equations. Both the main method and additional methods were derived via interpolation and collocation procedures. The basic properties of zero ...

  17. Modified Two-Step Dimethyl Ether (DME Synthesis Simulation from Indonesian Brown Coal

    Directory of Open Access Journals (Sweden)

    Dwiwahju Sasongko

    2016-08-01

    Full Text Available A theoretical study was conducted to investigate the performance of dimethyl ether (DME synthesis from coal. This paper presents a model for two-step DME synthesis from brown coal represented by the following processes: drying, gasification, water-gas reaction, acid gas removal, and DME synthesis reactions. The results of the simulation suggest that a feedstock ratio of coal : oxygen : steam of 1 : 0.13 : 0.821 produces the highest DME concentration. The water-gas reactor simulation at a temperature of 400°C and a pressure of 20 bar gave the ratio of H2/CO closest to 2, the optimal value for two-step DME synthesis. As for the DME synthesis reactor simulation, high pressure and low temperature promote a high DME concentration. It is predicted that a temperature of 300°C and a pressure of 140 bar are the optimum conditions for the DME synthesis reaction. This study also showed that the DME concentration produced by the two-step route is higher than that produced by one-step DME synthesis, implying that further improvement and research are needed to apply two-step DME synthesis to production of this liquid fuel.

  18. Liquid-phase reforming and hydrodeoxygenation as a two-step route to aromatics from lignin

    NARCIS (Netherlands)

    Jongerius, A.L.; Bruijnincx, P.C.A.; Weckhuysen, B.M.

    2013-01-01

    A two-step approach to the conversion of organosolv, kraft and sugarcane bagasse lignin to monoaromatic compounds of low oxygen content is presented. The first step consists of lignin depolymerization in a liquid phase reforming (LPR) reaction over a 1 wt% Pt/γ-Al2O3 catalyst at 225 °C in alkaline

  19. A novel two-step method for screening shade tolerant mutant plants via dwarfism

    Science.gov (United States)

    When subjected to shade, plants undergo rapid shoot elongation, which often makes them more prone to disease and mechanical damage. It has been reported that, in turfgrass, induced dwarfism can enhance shade tolerance. Here, we describe a two-step procedure for isolating shade tolerant mutants of ...

  20. Two-step estimation procedures for inhomogeneous shot-noise Cox processes

    DEFF Research Database (Denmark)

    Prokesová, Michaela; Dvorák, Jirí; Jensen, Eva B. Vedel

    In the present paper we develop several two-step estimation procedures for inhomogeneous shot-noise Cox processes. The intensity function is parametrized by the inhomogeneity parameters while the pair-correlation function is parametrized by the interaction parameters. The suggested procedures...

  1. Development of a two-step “green” synthesis for (-)-ambafuran production

    CSIR Research Space (South Africa)

    Steenkamp, Lucia H

    2010-09-01

    Full Text Available The main objective of the development of a two-step “green” synthesis for (-)-ambafuran production is to find an alternative synthesis of (-) Ambrox from sclareol, to use a bioconversion or biocatalysis route, and that it results in a natural...

  2. Photon strength function in the Hf-181 nucleus by method of two-step cascade

    International Nuclear Information System (INIS)

    Le Hong Khiem

    2003-01-01

    The applicability of sum-coincidence measurements of two-step cascade gamma ray spectra determining Photon Strength Function (PSF) of Hf-181 induced from Hf-180 (n,2γ) Hf-181 reaction is presented. Up to 80% intensity of the primary gamma ray transitions in a wide energy range have been deduced and compared to model calculation. (author)

  3. A two-step annealing process for enhancing the ferroelectric properties of poly(vinylidene fluoride) (PVDF) devices

    KAUST Repository

    Park, Jihoon; Kurra, Narendra; AlMadhoun, M. N.; Odeh, Ihab N.; Alshareef, Husam N.

    2015-01-01

    We report a simple two-step annealing scheme for the fabrication of stable non-volatile memory devices employing poly(vinylidene fluoride) (PVDF) polymer thin-films. The proposed two-step annealing scheme comprises the crystallization

  4. State of the art and prospective of lipase-catalyzed transesterification reaction for biodiesel production

    International Nuclear Information System (INIS)

    Amini, Zeynab; Ilham, Zul; Ong, Hwai Chyuan; Mazaheri, Hoora; Chen, Wei-Hsin

    2017-01-01

    Highlights: • Enzymatic transesterification process is less energy intensive and robust. • Nano-materials are promising immobilization supports for lipase. • Packed-bed reactors are appropriate for scale-up use. • Potential recombinant, whole cell and recombinant whole cell lipases were enlisted. • Genetic engineering is a promising prospect in biodiesel area. - Abstract: The world demand for fuel as energy sources have arisen the need for generating alternatives such as biofuel. Biodiesel is a renewable fuel used particularly in diesel engines. Currently, biodiesel is mainly produced through transesterification reactions catalyzed by chemical catalysts, which produces higher fatty acid alkyl esters in shorter reaction time. Although extensive investigations on enzymatic transesterification by downstream processing were carried out, enzymatic transesterification has yet to be used in scale-up since commercial lipases are chiefly limited to the cost as well as long reaction time. While numerous lipases were studied and proven to have the high catalytic capacity, still enzymatic reaction requires more investigation. To fill this gap, finding optimal conditions for the reaction such as alcohol and oil choice, water content, reaction time and temperature through proper reaction modelling and simulations as well as the appropriate design and use of reactors for large scale production are crucial issues that need to be accurately addressed. Furthermore, lipase concentration, alternative lipase resources through whole cell technology and genetic engineering, recent immobilizing materials including nanoparticles, and the capacity of enzyme to be reused are important criteria to be neatly investigated. The present work reviews the current biodiesel feedstock, catalysis, general and novel immobilizing materials, bioreactors for enzymatic transesterification, potential lipase resources, intensification technics, and process modelling for enzymatic

  5. Comparison of two-step versus four-step composite finishing/polishing disc systems: evaluation of a new two-step composite polishing disc system.

    Science.gov (United States)

    da Costa, Juliana B; Goncalves, Flavia; Ferracane, Jack L

    2011-01-01

    The purpose of this study was to evaluate surface finish and gloss of a two-step composite finishing/polishing (F/P) disc system compared with two multistep systems on five composites. Seventy-five disc-shaped composite specimens (D=10.0 mm, 2 mm thick, n=15 per composite) were made of microfill (Durafill-D), nanofill (Filtek Supreme-FS), nanohybrid (Premise-PR), and microhybrids (Filtek Z250-FZ, Esthet-EX). One side of each specimen was initially finished with a carbide bur. Five specimens of each resin composite were randomly assigned to receive full F/P by each of the disc systems: two-step (Enhance Flex NST-EF) and four-step (Sof-Lex-SL, Super-Snap-SS). Surface gloss was measured with a glossmeter and surface roughness was measured with a profilometer. Results were analyzed by two-way analysis of variance (ANOVA)/Tukey's (αgloss was noted among the three F/P systems when used with D and EX; no difference between SL and EF when used with any composite, except for FS; and no difference between SL and SS when used with any composite. SL and EF showed similar surface roughness when used on all composites, except for EX. EF and SS showed similar surface roughness on PR. SL and SS showed similar surface roughness values on every composite, except for FZ. EF was capable of providing similar gloss and surface roughness to SL on four composites evaluated but was not able to produce as glossy or as smooth a surface as SS for three of the five composites.

  6. Two-step flash light sintering of copper nanoparticle ink to remove substrate warping

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Chung-Hyeon; Joo, Sung-Jun [Department of Mechanical Convergence Engineering, Hanyang University, Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Kim, Hak-Sung, E-mail: kima@hanyang.ac.kr [Department of Mechanical Convergence Engineering, Hanyang University, Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Institute of Nano Science and Technology, Hanyang University, Seoul, 133-791 (Korea, Republic of)

    2016-10-30

    Highlights: • We performed the two-step flash light sintering for copper nanoparticle ink to remove substrate warping. • 12 J/cm{sup 2} of preheating and 7 J/cm{sup 2} of main sintering energies were determined as optimum conditions to sinter the copper nanoparticle ink. • The resistivity of two-step sintered copper nanoparticle ink was 3.81 μΩ cm with 5B adhesion level, 2.3 times greater than that of bulk copper. • The two-step sintered case showed a high conductivity without any substrate warping. - Abstract: A two-step flash light sintering process was devised to reduce the warping of polymer substrates during the sintering of copper nanoparticle ink. To determine the optimum sintering conditions of the copper nanoparticle ink, the flash light irradiation conditions (pulse power, pulse number, on-time, and off-time) were varied and optimized. In order to monitor the flash light sintering process, in situ resistance and temperature monitoring of copper nanoink were conducted during the flash light sintering process. Also, a transient heat transfer analysis was performed by using the finite-element program ABAQUS to predict the temperature changes of copper nanoink and polymer substrate. The microstructures of the sintered copper nanoink films were analyzed by scanning electron microscopy. Additionally, an X-ray diffraction and Fourier transform infrared spectroscopy were used to characterize the crystal phase change of the sintered copper nanoparticles. The resulting two-step flash light sintered copper nanoink films exhibited a low resistivity (3.81 μΩ cm, 2.3 times of that of bulk copper) and 5B level of adhesion strength without warping of the polymer substrate.

  7. Effectiveness of en masse versus two-step retraction: a systematic review and meta-analysis

    Directory of Open Access Journals (Sweden)

    Mumen Z. Rizk

    2018-01-01

    Full Text Available Abstract Background This review aims to compare the effectiveness of en masse and two-step retraction methods during orthodontic space closure regarding anchorage preservation and anterior segment retraction and to assess their effect on the duration of treatment and root resorption. Methods An electronic search for potentially eligible randomized controlled trials and prospective controlled trials was performed in five electronic databases up to July 2017. The process of study selection, data extraction, and quality assessment was performed by two reviewers independently. A narrative review is presented in addition to a quantitative synthesis of the pooled results where possible. The Cochrane risk of bias tool and the Newcastle-Ottawa Scale were used for the methodological quality assessment of the included studies. Results Eight studies were included in the qualitative synthesis in this review. Four studies were included in the quantitative synthesis. En masse/miniscrew combination showed a statistically significant standard mean difference regarding anchorage preservation − 2.55 mm (95% CI − 2.99 to − 2.11 and the amount of upper incisor retraction − 0.38 mm (95% CI − 0.70 to − 0.06 when compared to a two-step/conventional anchorage combination. Qualitative synthesis suggested that en masse retraction requires less time than two-step retraction with no difference in the amount of root resorption. Conclusions Both en masse and two-step retraction methods are effective during the space closure phase. The en masse/miniscrew combination is superior to the two-step/conventional anchorage combination with regard to anchorage preservation and amount of retraction. Limited evidence suggests that anchorage reinforcement with a headgear produces similar results with both retraction methods. Limited evidence also suggests that en masse retraction may require less time and that no significant differences exist in the amount of root

  8. 48 CFR 52.214-23 - Late submissions, modifications, revisions, and withdrawals of technical proposals under two-step...

    Science.gov (United States)

    2010-10-01

    ..., modifications, revisions, and withdrawals of technical proposals under two-step sealed bidding. 52.214-23... Late submissions, modifications, revisions, and withdrawals of technical proposals under two-step..., Modifications, Revisions, and Withdrawals of Technical Proposals Under Two-Step Sealed Bidding (NOV 1999) (a...

  9. Advances in catalysis

    International Nuclear Information System (INIS)

    Eley, D.D.; Pine, H.; Weisz, P.B.

    1989-01-01

    This book reports on the current state of knowledge concerning structure and catalysis of metals and metal oxide particles, old and new. It addresses the basic and broad problems of what the catalytically relevant surface structures of metals are, where we stand in techniques capable of attacking this problem, and what the current state of knowledge is. The focus is on long-standing, important, and central problem of general investigative methodology and strategy: the pressure gap is created by the fact that the best techniques of surface analysis require high-vacuum conditions, while useful catalysis is confined to conditions of near ambient or higher pressures. The authors review the basic question of the influence of particle size on catalytic behavior of metal particles which involves questions of the basic sciences as much as practical considerations of catalyst design and use. They discuss preparatory techniques, analytical technology, and methods of characterization of these materials

  10. Solid Base Catalysis

    CERN Document Server

    Ono, Yoshio

    2011-01-01

    The importance of solid base catalysts has come to be recognized for their environmentally benign qualities, and much significant progress has been made over the past two decades in catalytic materials and solid base-catalyzed reactions. The book is focused on the solid base. Because of the advantages over liquid bases, the use of solid base catalysts in organic synthesis is expanding. Solid bases are easier to dispose than liquid bases, separation and recovery of products, catalysts and solvents are less difficult, and they are non-corrosive. Furthermore, base-catalyzed reactions can be performed without using solvents and even in the gas phase, opening up more possibilities for discovering novel reaction systems. Using numerous examples, the present volume describes the remarkable role solid base catalysis can play, given the ever increasing worldwide importance of "green" chemistry. The reader will obtain an overall view of solid base catalysis and gain insight into the versatility of the reactions to whic...

  11. Biodegradable products by lipase biocatalysis.

    Science.gov (United States)

    Linko, Y Y; Lämsä, M; Wu, X; Uosukainen, E; Seppälä, J; Linko, P

    1998-11-18

    The interest in the applications of biocatalysis in organic syntheses has rapidly increased. In this context, lipases have recently become one of the most studied groups of enzymes. We have demonstrated that lipases can be used as biocatalyst in the production of useful biodegradable compounds. A number of examples are given. 1-Butyl oleate was produced by direct esterification of butanol and oleic acid to decrease the viscosity of biodiesel in winter use. Enzymic alcoholysis of vegetable oils without additional organic solvent has been little investigated. We have shown that a mixture of 2-ethyl-1-hexyl esters can be obtained in a good yield by enzymic transesterification from rapeseed oil fatty acids for use as a solvent. Trimethylolpropane esters were also similarly synthesized as lubricants. Finally, the discovery that lipases can also catalyze ester syntheses and transesterification reactions in organic solvent systems has opened up the possibility of enzyme catalyzed production of biodegradable polyesters. In direct polyesterification of 1,4-butanediol and sebacic acid, polyesters with a mass average molar mass of the order of 56,000 g mol-1 or higher, and a maximum molar mass of about 130,000 g mol-1 were also obtained by using lipase as biocatalyst. Finally, we have demonstrated that also aromatic polyesters can be synthesized by lipase biocatalysis, a higher than 50,000 g mol-1 mass average molar mass of poly(1,6-hexanediyl isophthalate) as an example.

  12. 21 CFR 184.1415 - Animal lipase.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Animal lipase. 184.1415 Section 184.1415 Food and... Substances Affirmed as GRAS § 184.1415 Animal lipase. (a) Animal lipase (CAS Reg. No. 9001-62-1) is an enzyme preparation obtained from edible forestomach tissue of calves, kids, or lambs, or from animal pancreatic...

  13. Stress corrosion cracking resistance of aluminum alloy 7000 series after two-step aging

    Directory of Open Access Journals (Sweden)

    Jegdić Bore V.

    2015-01-01

    Full Text Available The effect of one step-and a new (short two-step aging on the resistance to stress corrosion cracking of an aluminum alloy 7000 series was investigated, using slow strain rate test and fracture mechanics method. Aging level in the tested alloy was evaluated by means of scanning electron microscopy and measurements of electrical resistivity. It was shown that the alloy after the new two-step aging is significantly more resistant to stress corrosion cracking. Values of tensile properties and fracture toughness are similar for both thermal states. Processes that take place at the crack tip have been considered. The effect of the testing solution temperature on the crack growth rate on the plateau was determined. Two values of the apparent activation energy were obtained. These values correspond to different processes that control crack growth rate on the plateau at higher and lower temperatures. [Projekat Ministarstva nauke Republike Srbije, br. TR 34028 i br. TR 34016

  14. Two-step impression/ injection, an alternative putty/ wash impression technique: case report.

    Science.gov (United States)

    Caputi, S; Murmura, G; Sinjari, B; Varvara, G

    2012-01-01

    We here describe a new technique for making a definitive impression that we refer to as the two-step impression/injection technique. This technique initially follows the classical one-step putty/ light-body impression technique with the polymerization of the putty and the light-body compound. This is then followed by the second step: injection of extra-light-body compound into the preparation through a hole in the metal stock tray. The aim of this additional step is to control the wash bulk and minimize the changes that can produce unfavorable impression results. This new two-step impression/injection technique allows displacement of soft tissues, such as the tongue, during the first seating of the putty and wash materials, while in the second step, the extra-light-body compound records all of the finer details without being compressed.

  15. Kalman Filtering for Discrete Stochastic Systems with Multiplicative Noises and Random Two-Step Sensor Delays

    Directory of Open Access Journals (Sweden)

    Dongyan Chen

    2015-01-01

    Full Text Available This paper is concerned with the optimal Kalman filtering problem for a class of discrete stochastic systems with multiplicative noises and random two-step sensor delays. Three Bernoulli distributed random variables with known conditional probabilities are introduced to characterize the phenomena of the random two-step sensor delays which may happen during the data transmission. By using the state augmentation approach and innovation analysis technique, an optimal Kalman filter is constructed for the augmented system in the sense of the minimum mean square error (MMSE. Subsequently, the optimal Kalman filtering is derived for corresponding augmented system in initial instants. Finally, a simulation example is provided to demonstrate the feasibility and effectiveness of the proposed filtering method.

  16. Time dependent theory of two-step absorption of two pulses

    Energy Technology Data Exchange (ETDEWEB)

    Rebane, Inna, E-mail: inna.rebane@ut.ee

    2015-09-25

    The time dependent theory of two step-absorption of two different light pulses with arbitrary duration in the electronic three-level model is proposed. The probability that the third level is excited at the moment t is found in depending on the time delay between pulses, the spectral widths of the pulses and the energy relaxation constants of the excited electronic levels. The time dependent perturbation theory is applied without using “doorway–window” approach. The time and spectral behavior of the spectrum using in calculations as simple as possible model is analyzed. - Highlights: • Time dependent theory of two-step absorption in the three-level model is proposed. • Two different light pulses with arbitrary duration is observed. • The time dependent perturbation theory is applied without “door–window” approach. • The time and spectral behavior of the spectra is analyzed for several cases.

  17. Two-step approach to the dynamics of coupled anharmonic oscillators

    International Nuclear Information System (INIS)

    Chung, N. N.; Chew, L. Y.

    2009-01-01

    We have further extended the two-step approach developed by Chung and Chew [N. N. Chung and L. Y. Chew, Phys. Rev. A 76, 032113 (2007)] to the solution of the quantum dynamics of general systems of N-coupled anharmonic oscillators. The idea is to employ an optimized basis set to represent the dynamical quantum states of these oscillator systems. The set is generated via the action of the optimized Bogoliubov transformed bosonic operators on the optimal squeezed vacuum product state. The procedure requires (i) applying the two-step approach to the eigendecomposition of the time evolution operator and (ii) transforming the representation of the initial state from the original to the optimal bases. We have applied the formalism to examine the dynamics of squeezing and entanglement of several anharmonic oscillator systems.

  18. Effectiveness of a two-step population-based osteoporosis screening program using FRAX

    DEFF Research Database (Denmark)

    Rubin, K H; Rothmann, M J; Holmberg, T

    2018-01-01

    The Risk-stratified Osteoporosis Strategy Evaluation (ROSE) study investigated the effectiveness of a two-step screening program for osteoporosis in women. We found no overall reduction in fractures from systematic screening compared to the current case-finding strategy. The group of moderate......- to high-risk women, who accepted the invitation to DXA, seemed to benefit from the program. INTRODUCTION: The purpose of the ROSE study was to investigate the effectiveness of a two-step population-based osteoporosis screening program using the Fracture Risk Assessment Tool (FRAX) derived from a self......-administered questionnaire to select women for DXA scan. After the scanning, standard osteoporosis management according to Danish national guidelines was followed. METHODS: Participants were randomized to either screening or control group, and randomization was stratified according to age and area of residence. Inclusion...

  19. A two-step Hilbert transform method for 2D image reconstruction

    International Nuclear Information System (INIS)

    Noo, Frederic; Clackdoyle, Rolf; Pack, Jed D

    2004-01-01

    The paper describes a new accurate two-dimensional (2D) image reconstruction method consisting of two steps. In the first step, the backprojected image is formed after taking the derivative of the parallel projection data. In the second step, a Hilbert filtering is applied along certain lines in the differentiated backprojection (DBP) image. Formulae for performing the DBP step in fan-beam geometry are also presented. The advantage of this two-step Hilbert transform approach is that in certain situations, regions of interest (ROIs) can be reconstructed from truncated projection data. Simulation results are presented that illustrate very similar reconstructed image quality using the new method compared to standard filtered backprojection, and that show the capability to correctly handle truncated projections. In particular, a simulation is presented of a wide patient whose projections are truncated laterally yet for which highly accurate ROI reconstruction is obtained

  20. A two-step quantum secure direct communication protocol with hyperentanglement

    International Nuclear Information System (INIS)

    Gu Bin; Zhang Cheng-Yi; Huang Yu-Gai; Fang Xia

    2011-01-01

    We propose a two-step quantum secure direct communication (QSDC) protocol with hyperentanglement in both the spatial-mode and the polarization degrees of freedom of photon pairs which can in principle be produced with a beta barium borate crystal. The secret message can be encoded on the photon pairs with unitary operations in these two degrees of freedom independently. This QSDC protocol has a higher capacity than the original two-step QSDC protocol as each photon pair can carry 4 bits of information. Compared with the QSDC protocol based on hyperdense coding, this QSDC protocol has the immunity to Trojan horse attack strategies with the process for determining the number of the photons in each quantum signal as it is a one-way quantum communication protocol. (general)

  1. Core-shell polymer nanorods by a two-step template wetting process

    International Nuclear Information System (INIS)

    Dougherty, S; Liang, J

    2009-01-01

    One-dimensional core-shell polymer nanowires offer many advantages and great potential for many different applications. In this paper we introduce a highly versatile two-step template wetting process to fabricate two-component core-shell polymer nanowires with controllable shell thickness. PLLA and PMMA were chosen as model polymers to demonstrate the feasibility of this process. Solution wetting with different concentrations of polymer solutions was used to fabricate the shell layer and melt wetting was used to fill the shell with the core polymer. The shell thickness was analyzed as a function of the polymer solution concentration and viscosity, and the core-shell morphology was observed with TEM. This paper demonstrates the feasibility of fabricating polymer core-shell nanostructures using our two-step template wetting process and opens the arena for optimization and future experiments with polymers that are desirable for specific applications.

  2. ONE-STEP AND TWO-STEP CALIBRATION OF A PORTABLE PANORAMIC IMAGE MAPPING SYSTEM

    Directory of Open Access Journals (Sweden)

    P.-C. Wang

    2012-07-01

    Full Text Available A Portable Panoramic Image Mapping System (PPIMS is proposed for rapid acquisition of three-dimensional spatial information. By considering the convenience of use, cost, weight of equipment, precision, and power supply, the designed PPIMS is equipped with 6 circularly arranged cameras to capture panoramic images and a GPS receiver for positioning. The motivation for this design is to develop a hand-held Mobile Mapping System (MMS for some difficult accessing areas by vehicle MMS, such as rugged terrains, forest areas, heavily damaged disaster areas, and crowed places etc. This PPIMS is in fact a GPS assisted close-range photogrammetric system. Compared with the traditional close-range photogrammetry, PPIMS can reduce the need of ground control points significantly. Under the condition of knowing the relative geometric relationships of the equipped sensors, the elements of exterior orientation of each captured image can be solved. However, the procedure of a system calibration should be done accurately to determine the relative geometric relationships of multi-cameras and the GPS antenna center, before the PPIMS can be applied for geo-referenced mapping. In this paper, both of one-step and two-step calibration procedures for PPIMS are performed to determine the lever-arm offsets and boresight angles among cameras and GPS. The performance of the one-step and two-step calibration is evaluated through the analysis of the experimental results. The comparison between these two calibration procedures was also conducted. The two-step calibration method outperforms the one-step calibration method in terms of calibration accuracy and operation convenience. We expect that the proposed two-step calibration procedure can also be applied to other platform-based MMSs.

  3. ORDERED POROUS ANODIC ALUMINUM OXIDE FILMS MADE BY TWO-STEP ANODIZATION

    OpenAIRE

    HANSONG XUE; HUAJI LI; YU YI; HUIFANG HU

    2007-01-01

    Porous Anodic Aluminum Oxide (AAO) films were prepared by two-step anodizing in sulfuric and oxalic acid solutions and observed by transmission electron microscope (TEM) and X-ray diffraction. The results show that the form of AAO film is affected by the varieties and concentrations of electrolyte, anodizing voltage, and the anodizing time; the formation and evolution processes of the AAO film are relative with the anodizing voltage severely, and the appropriate voltage is helpful to the orde...

  4. Two-Step Classification of Unemployed People in the Czech Republic

    OpenAIRE

    Zdeněk Šulc; Marina Stecenková; Jiří Vild

    2015-01-01

    The paper analyzes structure and behavior of unemployed people in the Czech Republic by means of latent class analysis (LCA) and CHAID analysis where the output of LCA serves as the input for CHAID. The unemployed are classified in two steps; for each step different characteristics are used. In the first step, respondents are split into latent classes according to their answers to questions concerning ways of searching for a new job. In the second step, CHAID analysis is performed with result...

  5. Two-step resonance ionization spectroscopy of Na atomic beam using cw and pulsed lasers

    International Nuclear Information System (INIS)

    Katsuragawa, H.; Minowa, T.; Shimazu, M.

    1988-01-01

    Two-step photoionization of sodium atomic beam has been carried out using a cw and a pulsed dye lasers. Sodium ions have been detected by a time of flight method in order to reduce background noise. With a proper power of the pulsed dye laser the sodium atomic beam has been irradiated by a resonant cw dye laser. The density of the sodium atomic beam is estimated to be 10 3 cm -3 at the ionization area. (author)

  6. Tranfusion risk: is "two-step" vaginal delivery a risk for postpartum hemorrhage?

    Science.gov (United States)

    Straface, Gianluca; Bassi, Emma; De Santis, Marco; Scambia, Giovanni; Zanardo, Vincenzo

    2015-01-01

    In the active management strategy of third stage of labor, the optimal timing for clamping the umbilical cord after birth has been a subject of controversy. We want to evaluate if "two-step" delivery is a risk factor for postpartum hemorrhage (PPH), defined as need of transfusion, comparing to operative delivery, elective caesarean delivery and emergency caesarean delivery. This is a retrospective cohort study conducted in division of Perinatal Medicine, Policlinico Abano Terme. We evaluated the need of transfusion in all cases of PPH verified in all single deliveries between January 2011 and December 2012. The main outcome measure was blood loss and red blood cell transfusion. We found 17 cases of PPH (0.88%). The distribution of PPH in relation to mode of delivery was 0.71%, 2.46% and 1.98% respectively for two-step vaginal delivery (RR = 0.81 (0.56-1.22)), emergency cesarean section (RR = 2.88 (1.27-7.77)) and operative vaginal delivery (RR = 2.88 (0.59-5.66)). In labor induction there is a stronger relative risk association between PPH and as emergency cesarean delivery (p < 0.05) as operative vaginal delivery (p < 0.05). "Two-step" delivery approach did not increase the risk of PPH with respect to operative delivery, elective caesarean section and emergency caesarean section.

  7. Ultrasonic transesterification of Jatrophacurcas L. oil to biodiesel by a two-step process

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Xin; Fang, Zhen; Liu, Yun-hu [Biomass Group, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, 88 Xuefulu, Kunming, Yunnan Province 650223 (China)

    2010-12-15

    Transesterification of high free fatty acid content Jatropha oil with methanol to biodiesel catalyzed directly by NaOH and high-concentrated H{sub 2}SO{sub 4} or by two-step process were studied in an ultrasonic reactor at 60 C. If NaOH was used as catalyst, biodiesel yield was only 47.2% with saponification problem. With H{sub 2}SO{sub 4} as catalyst, biodiesel yield was increased to 92.8%. However, longer reaction time (4 h) was needed and the biodiesel was not stable. A two-step, acid-esterification and base-transesterification process was further used for biodiesel production. It was found that after the first-step pretreatment with H{sub 2}SO{sub 4} for 1 h, the acid value of Jatropha oil was reduced from 10.45 to 1.2 mg KOH/g, and subsequently, NaOH was used for the second-step transesterification. Stable and clear yellowish biodiesel was obtained with 96.4% yield after reaction for 0.5 h. The total production time was only 1.5 h that is just half of the previous reported. The two-step process with ultrasonic radiation is effective and time-saving for biodiesel production from Jatropha oil. (author)

  8. Ultrasonic transesterification of Jatrophacurcas L. oil to biodiesel by a two-step process

    Energy Technology Data Exchange (ETDEWEB)

    Deng Xin [Biomass Group, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, 88 Xuefulu, Kunming, Yunnan Province 650223 (China); Fang Zhen, E-mail: zhenfang@xtbg.ac.c [Biomass Group, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, 88 Xuefulu, Kunming, Yunnan Province 650223 (China); Liu Yunhu [Biomass Group, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, 88 Xuefulu, Kunming, Yunnan Province 650223 (China)

    2010-12-15

    Transesterification of high free fatty acid content Jatropha oil with methanol to biodiesel catalyzed directly by NaOH and high-concentrated H{sub 2}SO{sub 4} or by two-step process were studied in an ultrasonic reactor at 60 deg. C. If NaOH was used as catalyst, biodiesel yield was only 47.2% with saponification problem. With H{sub 2}SO{sub 4} as catalyst, biodiesel yield was increased to 92.8%. However, longer reaction time (4 h) was needed and the biodiesel was not stable. A two-step, acid-esterification and base-transesterification process was further used for biodiesel production. It was found that after the first-step pretreatment with H{sub 2}SO{sub 4} for 1 h, the acid value of Jatropha oil was reduced from 10.45 to 1.2 mg KOH/g, and subsequently, NaOH was used for the second-step transesterification. Stable and clear yellowish biodiesel was obtained with 96.4% yield after reaction for 0.5 h. The total production time was only 1.5 h that is just half of the previous reported. The two-step process with ultrasonic radiation is effective and time-saving for biodiesel production from Jatropha oil.

  9. Effect of two-step aging on the mechanical properties of AA2219 DC cast alloy

    Energy Technology Data Exchange (ETDEWEB)

    Elgallad, E.M., E-mail: eelgalla@uqac.ca; Zhang, Z.; Chen, X.-G.

    2015-02-11

    With its combination of high specific strength, good machinability and excellent weldability, AA2219 direct chill (DC) cast alloy has become a new category of materials for manufacturing large molds for the plastics and automotive industries. The effect of two-step aging on the microstructural evolution and mechanical properties of AA2219 DC cast alloy was investigated. The precipitate microstructure was characterized under different heat treatment conditions using differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). The poor mechanical properties of the air-quenched alloy were attributed to the presence of quench-induced coarse θ′ and θ precipitates, which had very limited contribution to the precipitation hardening during the aging treatment. The two-step aging treatment of the air-quenched AA2219 alloy involved the precipitation of GP zones in the first step followed by their transformation into fine θ″ strengthening precipitates in the second step, which considerably improved the mechanical properties. After undergoing 120 °C/36 h+190 °C/8 h two-step aging, the hardness, YS and UTS of the air-quenched alloy were increased by 27%, 46% and 15%, respectively, compared with 190 °C/8 h one-step aging.

  10. Ultrasonic transesterification of Jatrophacurcas L. oil to biodiesel by a two-step process

    International Nuclear Information System (INIS)

    Deng Xin; Fang Zhen; Liu Yunhu

    2010-01-01

    Transesterification of high free fatty acid content Jatropha oil with methanol to biodiesel catalyzed directly by NaOH and high-concentrated H 2 SO 4 or by two-step process were studied in an ultrasonic reactor at 60 deg. C. If NaOH was used as catalyst, biodiesel yield was only 47.2% with saponification problem. With H 2 SO 4 as catalyst, biodiesel yield was increased to 92.8%. However, longer reaction time (4 h) was needed and the biodiesel was not stable. A two-step, acid-esterification and base-transesterification process was further used for biodiesel production. It was found that after the first-step pretreatment with H 2 SO 4 for 1 h, the acid value of Jatropha oil was reduced from 10.45 to 1.2 mg KOH/g, and subsequently, NaOH was used for the second-step transesterification. Stable and clear yellowish biodiesel was obtained with 96.4% yield after reaction for 0.5 h. The total production time was only 1.5 h that is just half of the previous reported. The two-step process with ultrasonic radiation is effective and time-saving for biodiesel production from Jatropha oil.

  11. A two-step method for rapid characterization of electroosmotic flows in capillary electrophoresis.

    Science.gov (United States)

    Zhang, Wenjing; He, Muyi; Yuan, Tao; Xu, Wei

    2017-12-01

    The measurement of electroosmotic flow (EOF) is important in a capillary electrophoresis (CE) experiment in terms of performance optimization and stability improvement. Although several methods exist, there are demanding needs to accurately characterize ultra-low electroosmotic flow rates (EOF rates), such as in coated capillaries used in protein separations. In this work, a new method, called the two-step method, was developed to accurately and rapidly measure EOF rates in a capillary, especially for measuring the ultra-low EOF rates in coated capillaries. In this two-step method, the EOF rates were calculated by measuring the migration time difference of a neutral marker in two consecutive experiments, in which a pressure driven was introduced to accelerate the migration and the DC voltage was reversed to switch the EOF direction. Uncoated capillaries were first characterized by both this two-step method and a conventional method to confirm the validity of this new method. Then this new method was applied in the study of coated capillaries. Results show that this new method is not only fast in speed, but also better in accuracy. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Metallic nanosystems in catalysis

    International Nuclear Information System (INIS)

    Bukhtiyarov, Valerii I; Slin'ko, Mikhail G

    2001-01-01

    The reactivities of metallic nanosystems in catalytic processes are considered. The activities of nanoparticles in catalysis are due to their unique microstructures, electronic properties and high specific surfaces of the active centres. The problems of increasing the selectivities of catalytic processes are discussed using several nanosystems as examples. The mutual effects of components of bimetallic nanoparticles are discussed. The prospects for theoretical and experimental investigations into catalytic nanosystems and the construction of industrial catalysts based on them are evaluated. The bibliography includes 207 references.

  13. Eukaryotic expression system Pichia pastoris affects the lipase catalytic properties: a monolayer study.

    Directory of Open Access Journals (Sweden)

    Madiha Bou Ali

    Full Text Available Recombinant DNA methods are being widely used to express proteins in both prokaryotic and eukaryotic cells for both fundamental and applied research purposes. Expressed protein must be well characterized to be sure that it retains the same properties as the native one, especially when expressed protein will be used in the pharmaceutical field. In this aim, interfacial and kinetic properties of native, untagged recombinant and tagged recombinant forms of a pancreatic lipase were compared using the monomolecular film technique. Turkey pancreatic lipase (TPL was chosen as model. A kinetic study on the dependence of the stereoselectivity of these three forms on the surface pressure was performed using three dicaprin isomers spread in the form of monomolecular films at the air-water interface. The heterologous expression and the N-His-tag extension were found to modify the pressure preference and decrease the catalytic hydrolysis rate of three dicaprin isomers. Besides, the heterologous expression was found to change the TPL regioselectivity without affecting its stereospecificity contrary to the N-tag extension which retained that regioselectivity and changed the stereospecificity at high surface pressures. The study of parameters, termed Recombinant expression Effects on Catalysis (REC, N-Tag Effects on Catalysis (TEC, and N-Tag and Recombinant expression Effects on Catalysis (TREC showed that the heterologous expression effects on the catalytic properties of the TPL were more deleterious than the presence of an N-terminal tag extension.

  14. CATALYSIS OF CHEMICAL PROCESSES: PARTICULAR ...

    African Journals Online (AJOL)

    IICBA01

    secondary/high schools and universities, the inhibition of the chemical reactions is frequently ... As a result, the lesson catalysis is frequently included in chemistry education curricula at ... Misinterpretations in teaching and perception of catalysis ... profile is shown as a dependence of energy on reaction progress, without ...

  15. Spectroscopy in catalysis : an introduction

    NARCIS (Netherlands)

    Niemantsverdriet, J.W.

    2007-01-01

    Spectroscopy in Catalysis is an introduction to the most important analytical techniques that are nowadays used in catalysis and in catalytic surface chemistry. The aim of the book is to give the reader a feeling for the type of information that characterization techniques provide about questions

  16. Type 1 Does The Two-Step: Type 1 Secretion Substrates With A Functional Periplasmic Intermediate.

    Science.gov (United States)

    Smith, Timothy J; Sondermann, Holger; O'Toole, George A

    2018-06-04

    Bacteria have evolved several secretion strategies for polling and responding to environmental flux and insult. Of these, the type 1 secretion system (T1SS) is known to secrete an array of biologically diverse proteins - from small < 10 kDa bacteriocins to gigantic adhesins with a mass over 1 MDa. For the last several decades T1SS have been characterized as a one-step translocation strategy whereby the secreted substrate is transported directly into the extracellular environment from the cytoplasm with no periplasmic intermediate. Recent phylogenetic, biochemical, and genetic evidence point to a distinct sub-group of T1SS machinery linked with a bacterial transglutaminase-like cysteine proteinase (BTLCP), which uses a two-step secretion mechanism. BTLCP-linked T1SS transport a class of repeats-in-toxin (RTX) adhesins that are critical for biofilm formation. The prototype of this RTX adhesin group, LapA of Pseudomonas fluorescens Pf0-1, uses a novel N-terminal retention module to anchor the adhesin at the cell surface as a secretion intermediate threaded through the outer membrane-localized, TolC-like protein LapE. This secretion intermediate is post-translationally cleaved by the BTLCP family LapG protein to release LapA from its cognate T1SS pore. Thus, secretion of LapA and related RTX adhesins into the extracellular environment appears to be a T1SS-mediated, two-step process that involves a periplasmic intermediate. In this review, we contrast the T1SS machinery and substrates of the BLTCP-linked two-step secretion process with those of the classical one-step T1SS to better understand the newly recognized and expanded role of this secretion machinery. Copyright © 2018 American Society for Microbiology.

  17. Two-Step Oxidation of Refractory Gold Concentrates with Different Microbial Communities.

    Science.gov (United States)

    Wang, Guo-Hua; Xie, Jian-Ping; Li, Shou-Peng; Guo, Yu-Jie; Pan, Ying; Wu, Haiyan; Liu, Xin-Xing

    2016-11-28

    Bio-oxidation is an effective technology for treatment of refractory gold concentrates. However, the unsatisfactory oxidation rate and long residence time, which cause a lower cyanide leaching rate and gold recovery, are key factors that restrict the application of traditional bio-oxidation technology. In this study, the oxidation rate of refractory gold concentrates and the adaption of microorganisms were analyzed to evaluate a newly developed two-step pretreatment process, which includes a high temperature chemical oxidation step and a subsequent bio-oxidation step. The oxidation rate and recovery rate of gold were improved significantly after the two-step process. The results showed that the highest oxidation rate of sulfide sulfur could reach to 99.01 % with an extreme thermophile microbial community when the pulp density was 5%. Accordingly, the recovery rate of gold was elevated to 92.51%. Meanwhile, the results revealed that moderate thermophiles performed better than acidophilic mesophiles and extreme thermophiles, whose oxidation rates declined drastically when the pulp density was increased to 10% and 15%. The oxidation rates of sulfide sulfur with moderate thermophiles were 93.94% and 65.73% when the pulp density was increased to 10% and 15%, respectively. All these results indicated that the two-step pretreatment increased the oxidation rate of refractory gold concentrates and is a potential technology to pretreat the refractory sample. Meanwhile, owing to the sensitivity of the microbial community under different pulp density levels, the optimization of microbial community in bio-oxidation is necessary in industry.

  18. A novel two-step method for screening shade tolerant mutant plants via dwarfism

    Directory of Open Access Journals (Sweden)

    Wei Li

    2016-10-01

    Full Text Available When subjected to shade, plants undergo rapid shoot elongation, which often makes them more prone to disease and mechanical damage. Shade-tolerant plants can be difficult to breed; however, they offer a substantial benefit over other varieties in low-light areas. Although perennial ryegrass (Lolium perenne L. is a popular species of turf grasses because of their good appearance and fast establishment, the plant normally does not perform well under shade conditions. It has been reported that, in turfgrass, induced dwarfism can enhance shade tolerance. Here we describe a two-step procedure for isolating shade tolerant mutants of perennial ryegrass by first screening for dominant dwarf mutants, and then screening dwarf plants for shade tolerance. The two-step screening process to isolate shade tolerant mutants can be done efficiently with limited space at early seedling stages, which enables quick and efficient isolation of shade tolerant mutants, and thus facilitates development of shade tolerant new cultivars of turfgrasses. Using the method, we isolated 136 dwarf mutants from 300,000 mutagenized seeds, with 65 being shade tolerant (0.022%. When screened directly for shade tolerance, we recovered only four mutants from a population of 150,000 (0.003% mutagenized seeds. One shade tolerant mutant, shadow-1, was characterized in detail. In addition to dwarfism, shadow-1 and its sexual progeny displayed high degrees of tolerance to both natural and artificial shade. We showed that endogenous gibberellin (GA content in shadow-1 was higher than wild-type controls, and shadow-1 was also partially GA insensitive. Our novel, simple and effective two-step screening method should be applicable to breeding shade tolerant cultivars of turfgrasses, ground covers, and other economically important crop plants that can be used under canopies of existing vegetation to increase productivity per unit area of land.

  19. Structural studies on lipoprotein lipase

    International Nuclear Information System (INIS)

    Socorro, L.

    1985-01-01

    The structure of lipoprotein lipase is not known. The lack of information on its primary sequence has been due to the inability of preparing it in homogeneous and stable form. This research has focused on the structural characterization of lipoprotein lipase. The first approach taken was to develop a purification method using bovine milk and affinity chromatography on heparin-Sepharose. The protein obtained was a heterogeneous peak with the activity shifted towards the trailing edge fractions. These fractions only presented a 55 Kdalton band on polyacrylamide gel electrophoresis. Monoclonal antibodies against this band detected an endogenous, phenyl methane sulfonyl fluoride-sensitive protease responsible for the presence of lower molecular weight fragments. The second approach was to label the lipoprotein lipase with a radioactive, active site, directed probe. After incubation and affinity chromatography a complex [ 3 H]inhibitor enzyme was isolated with a stoichiometry of 1.00 +/- 0.2. The complex was digested with CNBr and the insoluble peptides at low ionic strength (>90% [ 3 H]dpm) were used for further purification. Differential extraction of the [ 3 H]-peptide, digestion with S. aureus V8 protease, and high performance liquid chromatography yielded a hexapeptide with a composition consistent with the consensus sequence of the active site peptides of many serine-esterase. This and the kinetic data imply this being the mechanism of action for lipoprotein lipase

  20. Two-Step Fair Scheduling of Continuous Media Streams over Error-Prone Wireless Channels

    Science.gov (United States)

    Oh, Soohyun; Lee, Jin Wook; Park, Taejoon; Jo, Tae-Chang

    In wireless cellular networks, streaming of continuous media (with strict QoS requirements) over wireless links is challenging due to their inherent unreliability characterized by location-dependent, bursty errors. To address this challenge, we present a two-step scheduling algorithm for a base station to provide streaming of continuous media to wireless clients over the error-prone wireless links. The proposed algorithm is capable of minimizing the packet loss rate of individual clients in the presence of error bursts, by transmitting packets in the round-robin manner and also adopting a mechanism for channel prediction and swapping.

  1. Maximizing Efficiency in Two-step Solar-thermochemical Fuel Production

    Energy Technology Data Exchange (ETDEWEB)

    Ermanoski, I. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-05-01

    Widespread solar fuel production depends on its economic viability, largely driven by the solar-to-fuel conversion efficiency. In this paper, the material and energy requirements in two-step solar-thermochemical cycles are considered.The need for advanced redox active materials is demonstrated, by considering the oxide mass flow requirements at a large scale. Two approaches are also identified for maximizing the efficiency: optimizing reaction temperatures, and minimizing the pressure in the thermal reduction step by staged thermal reduction. The results show that each approach individually, and especially the two in conjunction, result in significant efficiency gains.

  2. Forward-backward rapidity correlations in a two-step scenario

    International Nuclear Information System (INIS)

    Brogueira, P.; Dias de Deus, J.

    2007-01-01

    We argue that two-step models, like String and Glasma models, with creation first of sources extended in rapidity that after locally decay into particles, lead to long range forward-backward correlations due to fluctuations in the number or the colour of the sources, and to a similar expression for the F-B correlation parameter b. In the simplest String percolation scenario, b increases with centrality or the number of participating nucleons. However, asymptotically it decreases with energy. This is different from the Glasma model where b increases with both, centrality and energy

  3. Two-Step Condensation of the Ideal Bose Gas in Highly Anisotropic Traps

    International Nuclear Information System (INIS)

    van Druten, N.J.; Ketterle, W.

    1997-01-01

    The ideal Bose gas in a highly anisotropic harmonic potential is studied. It is found that Bose-Einstein condensation occurs in two distinct steps as the temperature is lowered. In the first step the specific heat shows a sharp feature, but the system still occupies many one-dimensional quantum states. In the second step, at a significantly lower temperature, the ground state becomes macroscopically occupied. It should be possible to verify these predictions using present-day atom traps. The two-step behavior can occur in a rather general class of anisotropic traps, including the box potential. copyright 1997 The American Physical Society

  4. Development of F2 two-step fluorination process for non-aqueous reprocessing

    International Nuclear Information System (INIS)

    1976-02-01

    To establish the F 2 two-step fluorination for stable and high recoveries of plutonium, the fluorination process has been studied with the simulated fuel to a FBR containing UO 2 - PuO 2 and non-radioactive fission products in the 2''phi fluid-bed. The process principle was demonstrated and the effect of FPs on fluorination of U and Pu and the possibility of reducing the Pu loss could be clarified. The feasibility of separating PuF 6 from UF 6 onto UO 2 F 2 by adsorption, was also indicated. (auth.)

  5. Safety of the two-step tuberculin skin test in Indian health care workers.

    Science.gov (United States)

    Christopher, Devasahayam J; Shankar, Deepa; Datey, Ashima; Zwerling, Alice; Pai, Madhukar

    2014-12-01

    Health care workers (HCW) in low and middle income countries are at high risk of nosocomial tuberculosis infection. Periodic screening of health workers for both TB disease and infection can play a critical role in TB infection control. Occupational health programs that implement serial tuberculin skin testing (TST) are advised to use a two-step baseline TST. This helps to ensure that boosting of waned immune response is not mistaken as new TB infection (i.e. conversion). However, there are no data on safety of the two-step TST in the Indian context where HCWs are repeatedly exposed. Nursing students were recruited from 2007 to 2009 at the Christian Medical College and Hospital, Vellore, India. Consenting nursing students were screened with a baseline two-step TST at the time of recruitment. From 2007 to 2008 adverse events were recorded when reported during the TST reading (Cohort A). Nurses recruited in the final study year (2009) answered an investigator administered questionnaire assessing all likely side-effects Cohort B). This information was extracted from the case report forms and analysed. Between 2007 and 09, 800 trainees consented to participate in the annual TB screening study and 779 did not have a past history of TB or recall a positive TST and were selected to administer TST. Of these, 755 returned for reading the result and had complete data and were included for the final analysis - 623 subjects in (cohort A) and 132 in (cohort B). These were included for the final analysis. In cohort A only 1.3% reported adverse events. In cohort B, as per the investigator administered questionnaire; 25% reported minor side effects. Itching and local pain were the most common side effects encountered. There were no major adverse events reported. In particular, the adverse events were similar in the second step of the test and not more severe. Screening of HCWs with two-step TST for LTBI is simple and safe, and hence suitable for wide scale implementation in high

  6. Two-Step Proximal Gradient Algorithm for Low-Rank Matrix Completion

    Directory of Open Access Journals (Sweden)

    Qiuyu Wang

    2016-06-01

    Full Text Available In this paper, we  propose a two-step proximal gradient algorithm to solve nuclear norm regularized least squares for the purpose of recovering low-rank data matrix from sampling of its entries. Each iteration generated by the proposed algorithm is a combination of the latest three points, namely, the previous point, the current iterate, and its proximal gradient point. This algorithm preserves the computational simplicity of classical proximal gradient algorithm where a singular value decomposition in proximal operator is involved. Global convergence is followed directly in the literature. Numerical results are reported to show the efficiency of the algorithm.

  7. Normal Range of Head-to-body Delivery Interval by Two-step Delivery

    Directory of Open Access Journals (Sweden)

    Hong-Yu Zhang

    2016-01-01

    Conclusions: The average time of head-to-body delivery interval was longer than 60 s by two-step delivery. Majority shoulders were delivered at the first contraction. Majority shoulders emerged from perineum rather from under pubic arch. The routine one-step method of shoulder delivery where the downward force applied is not necessary and is not the right direction. Baby's breath, making faces, sucking, bubble from noses and mouth, and the light blue color of the faces, all those signs during shoulder delivery indicated a normal live birth.

  8. Extended Kalman filter (EKF) application in vitamin C two-step fermentation process.

    Science.gov (United States)

    Wei, D; Yuan, W; Yuan, Z; Yin, G; Chen, M

    1993-01-01

    Based on kinetic model study of vitamin C two-step fermentation, the extended Kalman filter (EKF) theory is conducted for studying the process which is disturbed by white noise to some extent caused by the model, the fermentation system and operation fluctuation. EKF shows that calculated results from estimated process parameters agree with the experimental results considerably better than model prediction without using estimated parameters. Parameter analysis gives a better understanding of the kinetics and provides a basis for state estimation and state prediction.

  9. 'Synthetic lipase' production from a newly isolated Sporidiobolus pararoseus strain by submerged fermentation

    Directory of Open Access Journals (Sweden)

    Alessandra Smaniotto

    2012-12-01

    Full Text Available The lipase produced by a newly isolate Sporidiobolus pararoseus strain has potential catalysis ability for esterification reactions. In order to improve its synthetic activity, this work aimed at optimizing 'synthetic lipase' production by submerged fermentation of a conventional media based on peptone, yeast extract, NaCl and olive oil using experimental design technique. According to the results obtained in the first experimental design (2(4-1, yeast extract and NaCl concentrations were tested to further optimization by response surface methodology. The maximum 'synthetic lipase' activity obtained was 26.9 U/mL in the optimized media (5.0, 6.8, 7.0 and 1.0% (wt/v of peptone, yeast extract, NaCl and olive oil, respectively, representing a 6.36-fold increase compared to the initial medium. The time course of 'synthetic lipase' production in the optimized condition was evaluated in terms of synthetic activity, protease activity, biomass and total carbon and the maximum synthetic activity was observed during the stationary phase of growth.

  10. Modelling substrate specificity and enantioselectivity for lipases and esterases by substrate-imprinted docking

    Directory of Open Access Journals (Sweden)

    Tyagi Sadhna

    2009-06-01

    Full Text Available Abstract Background Previously, ways to adapt docking programs that were developed for modelling inhibitor-receptor interaction have been explored. Two main issues were discussed. First, when trying to model catalysis a reaction intermediate of the substrate is expected to provide more valid information than the ground state of the substrate. Second, the incorporation of protein flexibility is essential for reliable predictions. Results Here we present a predictive and robust method to model substrate specificity and enantioselectivity of lipases and esterases that uses reaction intermediates and incorporates protein flexibility. Substrate-imprinted docking starts with covalent docking of reaction intermediates, followed by geometry optimisation of the resulting enzyme-substrate complex. After a second round of docking the same substrate into the geometry-optimised structures, productive poses are identified by geometric filter criteria and ranked by their docking scores. Substrate-imprinted docking was applied in order to model (i enantioselectivity of Candida antarctica lipase B and a W104A mutant, (ii enantioselectivity and substrate specificity of Candida rugosa lipase and Burkholderia cepacia lipase, and (iii substrate specificity of an acetyl- and a butyrylcholine esterase toward the substrates acetyl- and butyrylcholine. Conclusion The experimentally observed differences in selectivity and specificity of the enzymes were reproduced with an accuracy of 81%. The method was robust toward small differences in initial structures (different crystallisation conditions or a co-crystallised ligand, although large displacements of catalytic residues often resulted in substrate poses that did not pass the geometric filter criteria.

  11. Role of active site rigidity in activity: MD simulation and fluorescence study on a lipase mutant.

    Directory of Open Access Journals (Sweden)

    Md Zahid Kamal

    Full Text Available Relationship between stability and activity of enzymes is maintained by underlying conformational flexibility. In thermophilic enzymes, a decrease in flexibility causes low enzyme activity while in less stable proteins such as mesophiles and psychrophiles, an increase in flexibility is associated with enhanced enzyme activity. Recently, we identified a mutant of a lipase whose stability and activity were enhanced simultaneously. In this work, we probed the conformational dynamics of the mutant and the wild type lipase, particularly flexibility of their active site using molecular dynamic simulations and time-resolved fluorescence techniques. In contrast to the earlier observations, our data show that active site of the mutant is more rigid than wild type enzyme. Further investigation suggests that this lipase needs minimal reorganization/flexibility of active site residues during its catalytic cycle. Molecular dynamic simulations suggest that catalytically competent active site geometry of the mutant is relatively more preserved than wild type lipase, which might have led to its higher enzyme activity. Our study implies that widely accepted positive correlation between conformation flexibility and enzyme activity need not be stringent and draws attention to the possibility that high enzyme activity can still be accomplished in a rigid active site and stable protein structures. This finding has a significant implication towards better understanding of involvement of dynamic motions in enzyme catalysis and enzyme engineering through mutations in active site.

  12. Fabrication of conductive copper patterns using reactive inkjet printing followed by two-step electroless plating

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jin-Ju; Lin, Guo-Qiang; Wang, Yan [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054 (China); Sowade, Enrico; Baumann, Reinhard R. [Digital Printing and Imaging Technology, Technische Universität Chemnitz, Chemnitz, 09126 (Germany); Feng, Zhe-Sheng, E-mail: fzs@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054 (China)

    2017-02-28

    Highlights: • Copper patterns were fabricated by reactive inkjet printing and two-step electroless plating. • Cu particles produced via reactive inkjet printing act as catalyst for copper electroless plating. • High conductivity can be obtained without many printing passes and high temperature sintering. • This approach can largely avoid nozzle-clogging problems. • This approach presents a potential way in the flexible printed electronics with simple process. - Abstract: A simple and low-cost process for fabricating conductive copper patterns on flexible polyimide substrates was demonstrated. Copper catalyst patterns were first produced on polyimide substrates using reactive inkjet printing of Cu (II)-bearing ink and reducing ink, and then the conductive copper patterns were generated after a two-step electroless plating procedure. The copper layers were characterized by optical microscope, SEM, XRD and EDS. Homogeneously distributed copper nanoclusters were found in the catalyst patterns. A thin copper layer with uniform particle size was formed after first-step electroless plating, and a thick copper layer of about 14.3 μm with closely packed structure and fine crystallinity was produced after second-step electroless plating. This resulting copper layer had good solderability, reliable adhesion strength and a low resistivity of 5.68 μΩ cm without any sintering process.

  13. A simple two-step method to fabricate highly transparent ITO/polymer nanocomposite films

    International Nuclear Information System (INIS)

    Liu, Haitao; Zeng, Xiaofei; Kong, Xiangrong; Bian, Shuguang; Chen, Jianfeng

    2012-01-01

    Highlights: ► A simple two-step method without further surface modification step was employed. ► ITO nanoparticles were easily to be uniformly dispersed in polymer matrix. ► ITO/polymer nanocomposite film had high transparency and UV/IR blocking properties. - Abstract: Transparent functional indium tin oxide (ITO)/polymer nanocomposite films were fabricated via a simple approach with two steps. Firstly, the functional monodisperse ITO nanoparticles were synthesized via a facile nonaqueous solvothermal method using bifunctional chemical agent (N-methyl-pyrrolidone, NMP) as the reaction solvent and surface modifier. Secondly, the ITO/acrylics polyurethane (PUA) nanocomposite films were fabricated by a simple sol-solution mixing method without any further surface modification step as often employed traditionally. Flower-like ITO nanoclusters with about 45 nm in diameter were mono-dispersed in ethyl acetate and each nanocluster was assembled by nearly spherical nanoparticles with primary size of 7–9 nm in diameter. The ITO nanoclusters exhibited an excellent dispersibility in polymer matrix of PUA, remaining their original size without any further agglomeration. When the loading content of ITO nanoclusters reached to 5 wt%, the transparent functional nanocomposite film featured a high transparency more than 85% in the visible light region (at 550 nm), meanwhile cutting off near-infrared radiation about 50% at 1500 nm and blocking UV ray about 45% at 350 nm. It could be potential for transparent functional coating materials applications.

  14. Assessment of assembly homogenized two-steps core dynamic calculations using direct whole core transport solutions

    International Nuclear Information System (INIS)

    Hursin, Mathieu; Downar, Thomas J.; Yoon, Joo Il; Joo, Han Gyu

    2016-01-01

    Highlights: • Reactivity initiated accident analysis with direct whole core transient transport code. • Comparison with usual “two steps” procedure. • Effect of effective delayed neutron fraction definition on energy deposition in the fuel. • Effect of homogenized few-group cross sections generation at the assembly level on energy deposition in the fuel. • Effect of effective fuel temperature definition on energy deposition in the fuel. - Abstract: The impact of the approximations in the “two-steps” procedure used in the current generation of nodal simulators for core transient calculations is assessed by using a higher order solution obtained from a direct, whole core, transient transport calculation. A control rod ejection accident in an idealized minicore is analyzed with PARCS, which uses the two-steps procedure and DeCART which provides the higher order solution. DeCART is used as lattice code to provide the homogenized cross sections and kinetics parameters to PARCS. The approximations made by using (1) the homogenized few-group cross sections and kinetic parameters generated at the assembly level, (2) an effective delayed neutrons fraction, (3) an effective fuel temperature and (4) the few-group formulation are investigated in terms of global and local core power behavior. The results presented in the paper show that the current two-steps procedure produces sufficiently accurate transient results with respect to the direct whole core calculation solution, provided that its parameters are carefully generated using the prescriptions described in the present article.

  15. Magnetic properties of nickel nanowires decorated with cobalt nanoparticles fabricated by two step electrochemical deposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Maaz, K., E-mail: maaz@impcas.ac.cn [Materials Research Center, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China); Nanomaterials Research Group, Physics Division, PINSTECH, Nilore, 45650, Islamabad (Pakistan); Duan, J.L. [Materials Research Center, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China); Karim, S. [Nanomaterials Research Group, Physics Division, PINSTECH, Nilore, 45650, Islamabad (Pakistan); Chen, Y.H.; Yao, H.J.; Mo, D.; Sun, Y.M. [Materials Research Center, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China); Liu, J., E-mail: j.liu@impcas.ac.cn [Materials Research Center, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China)

    2016-10-01

    We demonstrate fabrication and magnetic characterization of novel nanostructures composed of Ni nanowires decorated with Co nanoparticles by two step etching and electrochemical deposition in polycarbonate template. Structural analysis confirmed the formation of nickel nanowires with diameter of 62 nm which are surrounded by cobalt nanoparticles of about 15 nm in diameter. By electron microscopy analyses it is evident that the nanoparticles are distributed on the surface of the nanowires. Analysis of magnetization data indicates that ferromagnetic Ni nanowires exhibit an easy axis of magnetization parallel to the wire long-axis while the angular dependence of coercivity indicates that magnetization reversal occurs through the curling process in these nanowires. An exchange bias accompanied by vertical shift in magnetization was observed below ∼20 K, measured under a cooling field of 1 kOe, which is attributed to the spin interactions between the spin-glass like surface layer and ferromagnetic core of the nanowires and nanoparticles. - Highlights: • Co-decorated Ni nanowires were fabricated by two-step electrodeposition technique. • The nanoparticles are distributed on the surface of nanowires. • Magnetization reversal occurs through the curling process in the nanowires. • Temperature dependent coercivity follows thermal activation model.

  16. A Two-Step Approach to Uncertainty Quantification of Core Simulators

    Directory of Open Access Journals (Sweden)

    Artem Yankov

    2012-01-01

    Full Text Available For the multiple sources of error introduced into the standard computational regime for simulating reactor cores, rigorous uncertainty analysis methods are available primarily to quantify the effects of cross section uncertainties. Two methods for propagating cross section uncertainties through core simulators are the XSUSA statistical approach and the “two-step” method. The XSUSA approach, which is based on the SUSA code package, is fundamentally a stochastic sampling method. Alternatively, the two-step method utilizes generalized perturbation theory in the first step and stochastic sampling in the second step. The consistency of these two methods in quantifying uncertainties in the multiplication factor and in the core power distribution was examined in the framework of phase I-3 of the OECD Uncertainty Analysis in Modeling benchmark. With the Three Mile Island Unit 1 core as a base model for analysis, the XSUSA and two-step methods were applied with certain limitations, and the results were compared to those produced by other stochastic sampling-based codes. Based on the uncertainty analysis results, conclusions were drawn as to the method that is currently more viable for computing uncertainties in burnup and transient calculations.

  17. Design of a Two-Step Calibration Method of Kinematic Parameters for Serial Robots

    Science.gov (United States)

    WANG, Wei; WANG, Lei; YUN, Chao

    2017-03-01

    Serial robots are used to handle workpieces with large dimensions, and calibrating kinematic parameters is one of the most efficient ways to upgrade their accuracy. Many models are set up to investigate how many kinematic parameters can be identified to meet the minimal principle, but the base frame and the kinematic parameter are indistinctly calibrated in a one-step way. A two-step method of calibrating kinematic parameters is proposed to improve the accuracy of the robot's base frame and kinematic parameters. The forward kinematics described with respect to the measuring coordinate frame are established based on the product-of-exponential (POE) formula. In the first step the robot's base coordinate frame is calibrated by the unit quaternion form. The errors of both the robot's reference configuration and the base coordinate frame's pose are equivalently transformed to the zero-position errors of the robot's joints. The simplified model of the robot's positioning error is established in second-power explicit expressions. Then the identification model is finished by the least square method, requiring measuring position coordinates only. The complete subtasks of calibrating the robot's 39 kinematic parameters are finished in the second step. It's proved by a group of calibration experiments that by the proposed two-step calibration method the average absolute accuracy of industrial robots is updated to 0.23 mm. This paper presents that the robot's base frame should be calibrated before its kinematic parameters in order to upgrade its absolute positioning accuracy.

  18. Two-step bioleaching of copper and gold from discarded printed circuit boards (PCB).

    Science.gov (United States)

    Işıldar, Arda; van de Vossenberg, Jack; Rene, Eldon R; van Hullebusch, Eric D; Lens, Piet N L

    2016-11-01

    An effective strategy for environmentally sound biological recovery of copper and gold from discarded printed circuit boards (PCB) in a two-step bioleaching process was experimented. In the first step, chemolithotrophic acidophilic Acidithiobacillus ferrivorans and Acidithiobacillus thiooxidans were used. In the second step, cyanide-producing heterotrophic Pseudomonas fluorescens and Pseudomonas putida were used. Results showed that at a 1% pulp density (10g/L PCB concentration), 98.4% of the copper was bioleached by a mixture of A. ferrivorans and A. thiooxidans at pH 1.0-1.6 and ambient temperature (23±2°C) in 7days. A pure culture of P. putida (strain WCS361) produced 21.5 (±1.5)mg/L cyanide with 10g/L glycine as the substrate. This gold complexing agent was used in the subsequent bioleaching step using the Cu-leached (by A. ferrivorans and A. thiooxidans) PCB material, 44.0% of the gold was mobilized in alkaline conditions at pH 7.3-8.6, and 30°C in 2days. This study provided a proof-of-concept of a two-step approach in metal bioleaching from PCB, by bacterially produced lixiviants. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Preparation of biodiesel from waste cooking oil via two-step catalyzed process

    International Nuclear Information System (INIS)

    Wang Yong; Liu Pengzhan; Ou Shiyi; Zhang Zhisen

    2007-01-01

    Waste cooking oils (WCO), which contain large amounts of free fatty acids produced in restaurants, are collected by the environmental protection agency in the main cities of China and should be disposed in a suitable way. In this research, a two step catalyzed process was adopted to prepare biodiesel from waste cooking oil whose acid value was 75.92 ± 0.036 mgKOH/g. The free fatty acids of WCO were esterified with methanol catalyzed by ferric sulfate in the first step, and the triglycerides (TGs) in WCO were transesterified with methanol catalyzed by potassium hydroxide in the second step. The results showed that ferric sulfate had high activity to catalyze the esterification of free fatty acids (FFA) with methanol, The conversion rate of FFA reached 97.22% when 2 wt% of ferric sulfate was added to the reaction system containing methanol to TG in10:1 (mole ratio) composition and reacted at 95 deg. C for 4 h. The methanol was vacuum evaporated, and transesterification of the remained triglycerides was performed at 65 deg. C for 1 h in a reaction system containing 1 wt% of potassium hydroxide and 6:1 mole ratio of methanol to TG. The final product with 97.02% of biodiesel, obtained after the two step catalyzed process, was analyzed by gas chromatography. This new process has many advantages compared with the old processes, such as no acidic waste water, high efficiency, low equipment cost and easy recovery of the catalyst

  20. Fabrication of conductive copper patterns using reactive inkjet printing followed by two-step electroless plating

    International Nuclear Information System (INIS)

    Chen, Jin-Ju; Lin, Guo-Qiang; Wang, Yan; Sowade, Enrico; Baumann, Reinhard R.; Feng, Zhe-Sheng

    2017-01-01

    Highlights: • Copper patterns were fabricated by reactive inkjet printing and two-step electroless plating. • Cu particles produced via reactive inkjet printing act as catalyst for copper electroless plating. • High conductivity can be obtained without many printing passes and high temperature sintering. • This approach can largely avoid nozzle-clogging problems. • This approach presents a potential way in the flexible printed electronics with simple process. - Abstract: A simple and low-cost process for fabricating conductive copper patterns on flexible polyimide substrates was demonstrated. Copper catalyst patterns were first produced on polyimide substrates using reactive inkjet printing of Cu (II)-bearing ink and reducing ink, and then the conductive copper patterns were generated after a two-step electroless plating procedure. The copper layers were characterized by optical microscope, SEM, XRD and EDS. Homogeneously distributed copper nanoclusters were found in the catalyst patterns. A thin copper layer with uniform particle size was formed after first-step electroless plating, and a thick copper layer of about 14.3 μm with closely packed structure and fine crystallinity was produced after second-step electroless plating. This resulting copper layer had good solderability, reliable adhesion strength and a low resistivity of 5.68 μΩ cm without any sintering process.

  1. Simple Plans or Sophisticated Habits? State, Transition and Learning Interactions in the Two-Step Task.

    Science.gov (United States)

    Akam, Thomas; Costa, Rui; Dayan, Peter

    2015-12-01

    The recently developed 'two-step' behavioural task promises to differentiate model-based from model-free reinforcement learning, while generating neurophysiologically-friendly decision datasets with parametric variation of decision variables. These desirable features have prompted its widespread adoption. Here, we analyse the interactions between a range of different strategies and the structure of transitions and outcomes in order to examine constraints on what can be learned from behavioural performance. The task involves a trade-off between the need for stochasticity, to allow strategies to be discriminated, and a need for determinism, so that it is worth subjects' investment of effort to exploit the contingencies optimally. We show through simulation that under certain conditions model-free strategies can masquerade as being model-based. We first show that seemingly innocuous modifications to the task structure can induce correlations between action values at the start of the trial and the subsequent trial events in such a way that analysis based on comparing successive trials can lead to erroneous conclusions. We confirm the power of a suggested correction to the analysis that can alleviate this problem. We then consider model-free reinforcement learning strategies that exploit correlations between where rewards are obtained and which actions have high expected value. These generate behaviour that appears model-based under these, and also more sophisticated, analyses. Exploiting the full potential of the two-step task as a tool for behavioural neuroscience requires an understanding of these issues.

  2. a Two-Step Classification Approach to Distinguishing Similar Objects in Mobile LIDAR Point Clouds

    Science.gov (United States)

    He, H.; Khoshelham, K.; Fraser, C.

    2017-09-01

    Nowadays, lidar is widely used in cultural heritage documentation, urban modeling, and driverless car technology for its fast and accurate 3D scanning ability. However, full exploitation of the potential of point cloud data for efficient and automatic object recognition remains elusive. Recently, feature-based methods have become very popular in object recognition on account of their good performance in capturing object details. Compared with global features describing the whole shape of the object, local features recording the fractional details are more discriminative and are applicable for object classes with considerable similarity. In this paper, we propose a two-step classification approach based on point feature histograms and the bag-of-features method for automatic recognition of similar objects in mobile lidar point clouds. Lamp post, street light and traffic sign are grouped as one category in the first-step classification for their inter similarity compared with tree and vehicle. A finer classification of the lamp post, street light and traffic sign based on the result of the first-step classification is implemented in the second step. The proposed two-step classification approach is shown to yield a considerable improvement over the conventional one-step classification approach.

  3. Two-step flash light sintering process for crack-free inkjet-printed Ag films

    International Nuclear Information System (INIS)

    Park, Sung-Hyeon; Kim, Hak-Sung; Jang, Shin; Lee, Dong-Jun; Oh, Jehoon

    2013-01-01

    In this paper, a two-step flash light sintering process for inkjet-printed Ag films is investigated with the aim of improving the quality of sintered Ag films. The flash light sintering process is divided into two steps: a preheating step and a main sintering step. The preheating step is used to remove the organic binder without abrupt vaporization. The main sintering step is used to complete the necking connections among the silver nanoparticles and achieve high electrical conductivity. The process minimizes the damage on the polymer substrate and the interface between the sintered Ag film and polymer substrate. The electrical conductivity is calculated by measuring the resistance and cross-sectional area with an LCR meter and 3D optical profiler, respectively. It is found that the resistivity of the optimal flash light-sintered Ag films (36.32 nΩ m), which is 228.86% of that of bulk silver, is lower than that of thermally sintered ones (40.84 nΩ m). Additionally, the polyimide film used as the substrate is preserved with the inkjet-printed pattern shape during the flash light sintering process without delamination or defects. (paper)

  4. Efficient Hydrolysis of Rice Straw into Xylose and Glucose by a Two-step Process

    Directory of Open Access Journals (Sweden)

    YAN Lu-lu

    2016-07-01

    Full Text Available The hydrolysis of rice straw into xylose and glucose in dilute sulfuric acid aqueous solution was studied with a two-step process in batch autoclave reactor. The results showed that compared with the traditional one-step acid hydrolysis, both xylose and glucose could be produced in high yields from rice straw by using the two-step acid hydrolysis process. The effects of reaction temperature, reaction time, the amount of rice straw and acid concentration on the hydrolysis of rice straw were systematically studied, and showed that except initial rice straw loading amount, the other parameters had remarkable influence on the products distribution and yields. In the first-step of the hydrolysis process, a high xylose yield of 162.6 g·kg-1 was obtained at 140℃ after 120 min reaction time. When the solid residues from the first step were subjected to a second-step hydrolysis, a glucose yield as high as 216.5 g·kg-1 could be achieved at 180℃ after 120 min. This work provides a promising strategy for the efficient and value-added utilization of agricultural wastes such as rice straw.

  5. Two steps hydrothermal growth and characterisations of BaTiO3 films composed of nanowires

    Science.gov (United States)

    Zawawi, Che Zaheerah Najeehah Che Mohd; Salleh, Shahril; Oon Jew, Lee; Tufail Chaudhary, Kashif; Helmi, Mohamad; Safwan Aziz, Muhammad; Haider, Zuhaib; Ali, Jalil

    2018-05-01

    Barium titanate (BaTiO3) films composed of nanowires have gained considerable research interest due to their lead-free composition and strong energy conversion efficiency. BaTiO3 films can be developed with a simple two steps hydrothermal reactions, which are low cost effective. In this research, BaTiO3 films were fabricated on titanium foil through two steps hydrothermal method namely, the growth of TiO2 and followed by BaTiO3 films. The structural evolutions and the dielectric properties of the films were investigated as well. The structural evolutions of titanium dioxide (TiO2) and BaTiO3 nanowires were characterized using X-ray diffraction and scanning electron microscopy. First step of hydrothermal reaction, TiO2 nanowires were prepared in varied temperatures of 160 °C, 200 °C and 250 °C respectively. Second step of hydrothermal reaction was performed to produce a layer of BaTiO3 films.

  6. Preparation and photocatalytic degradation performance of Ag_3PO_4 with a two-step approach

    International Nuclear Information System (INIS)

    Li, Jiwen; Ji, Xiaojing; Li, Xian; Hu, Xianghua; Sun, Yanfang; Ma, Jingjun; Qiao, Gaowei

    2016-01-01

    Highlights: • Ag_3PO_4 photocatalysts were synthesized via one-step and two-step ion-exchange reaction. • Photocatalytic properties of Ag_3PO_4 photocatalysts was investigated, the result indicated the Ag_3PO_4 (2) was higher than that of Ag_3PO_4 (1) under the same experimental condition. • Ag_3PO_4 (2) particles were larger than Ag_3PO_4 (1) particles and many polygonal-shaped surfaces could be clearly observed in the Ag_3PO_4 (2) particles. - Abstract: Ag_3PO_4 photocatalysts were prepared via two and one-step through a facile ion-exchange route. The photocatalysts were then characterized through powder X-ray diffraction, scanning electron microscopy and UV–vis diffuse reflectance spectroscopy. The photocatalytic activity of the samples was evaluated on the basis of the photocatalytic degradation of methyl orange (MO) and methylene blue (MB) under solar irradiation. The MO degradation rate of the Photocatalyst synthesized by the two-step ion-exchange route was 89.18% in 60 min. This value was four times that of the Photocatalyst synthesized by the one-step approach.The MB degradation rate was 97% in 40 min. After six cycling runs were completed, the MO degradation rate was 73%

  7. Two-step tunneling technique of deep brain stimulation extension wires-a description.

    Science.gov (United States)

    Fontaine, Denys; Vandersteen, Clair; Saleh, Christian; von Langsdorff, Daniel; Poissonnet, Gilles

    2013-12-01

    While a significant body of literature exists on the intracranial part of deep brain stimulation surgery, the equally important second part of the intervention related to the subcutaneous tunneling of deep brain stimulation extension wires is rarely described. The tunneling strategy can consist of a single passage of the extension wires from the frontal incision site to the subclavicular area, or of a two-step approach that adds a retro-auricular counter-incision. Each technique harbors the risk of intraoperative and postoperative complications. At our center, we perform a two-step tunneling procedure that we developed based on a cadaveric study. In 125 consecutive patients operated since 2002, we did not encounter any complication related to our tunneling method. Insufficient data exist to fully evaluate the advantages and disadvantages of each tunneling technique. It is of critical importance that authors detail their tunneling modus operandi and report the presence or absence of complications. This gathered data pool may help to formulate a definitive conclusions on the safest method for subcutaneous tunneling of extension wires in deep brain stimulation.

  8. Simple Plans or Sophisticated Habits? State, Transition and Learning Interactions in the Two-Step Task.

    Directory of Open Access Journals (Sweden)

    Thomas Akam

    2015-12-01

    Full Text Available The recently developed 'two-step' behavioural task promises to differentiate model-based from model-free reinforcement learning, while generating neurophysiologically-friendly decision datasets with parametric variation of decision variables. These desirable features have prompted its widespread adoption. Here, we analyse the interactions between a range of different strategies and the structure of transitions and outcomes in order to examine constraints on what can be learned from behavioural performance. The task involves a trade-off between the need for stochasticity, to allow strategies to be discriminated, and a need for determinism, so that it is worth subjects' investment of effort to exploit the contingencies optimally. We show through simulation that under certain conditions model-free strategies can masquerade as being model-based. We first show that seemingly innocuous modifications to the task structure can induce correlations between action values at the start of the trial and the subsequent trial events in such a way that analysis based on comparing successive trials can lead to erroneous conclusions. We confirm the power of a suggested correction to the analysis that can alleviate this problem. We then consider model-free reinforcement learning strategies that exploit correlations between where rewards are obtained and which actions have high expected value. These generate behaviour that appears model-based under these, and also more sophisticated, analyses. Exploiting the full potential of the two-step task as a tool for behavioural neuroscience requires an understanding of these issues.

  9. A TWO-STEP CLASSIFICATION APPROACH TO DISTINGUISHING SIMILAR OBJECTS IN MOBILE LIDAR POINT CLOUDS

    Directory of Open Access Journals (Sweden)

    H. He

    2017-09-01

    Full Text Available Nowadays, lidar is widely used in cultural heritage documentation, urban modeling, and driverless car technology for its fast and accurate 3D scanning ability. However, full exploitation of the potential of point cloud data for efficient and automatic object recognition remains elusive. Recently, feature-based methods have become very popular in object recognition on account of their good performance in capturing object details. Compared with global features describing the whole shape of the object, local features recording the fractional details are more discriminative and are applicable for object classes with considerable similarity. In this paper, we propose a two-step classification approach based on point feature histograms and the bag-of-features method for automatic recognition of similar objects in mobile lidar point clouds. Lamp post, street light and traffic sign are grouped as one category in the first-step classification for their inter similarity compared with tree and vehicle. A finer classification of the lamp post, street light and traffic sign based on the result of the first-step classification is implemented in the second step. The proposed two-step classification approach is shown to yield a considerable improvement over the conventional one-step classification approach.

  10. A two-step method for developing a control rod program for boiling water reactors

    International Nuclear Information System (INIS)

    Taner, M.S.; Levine, S.H.; Hsiao, M.Y.

    1992-01-01

    This paper reports on a two-step method that is established for the generation of a long-term control rod program for boiling water reactors (BWRs). The new method assumes a time-variant target power distribution in core depletion. In the new method, the BWR control rod programming is divided into two steps. In step 1, a sequence of optimal, exposure-dependent Haling power distribution profiles is generated, utilizing the spectral shift concept. In step 2, a set of exposure-dependent control rod patterns is developed by using the Haling profiles generated at step 1 as a target. The new method is implemented in a computer program named OCTOPUS. The optimization procedure of OCTOPUS is based on the method of approximation programming, in which the SIMULATE-E code is used to determine the nucleonics characteristics of the reactor core state. In a test in cycle length over a time-invariant, target Haling power distribution case because of a moderate application of spectral shift. No thermal limits of the core were violated. The gain in cycle length could be increased further by broadening the extent of the spetral shift

  11. Two-level image authentication by two-step phase-shifting interferometry and compressive sensing

    Science.gov (United States)

    Zhang, Xue; Meng, Xiangfeng; Yin, Yongkai; Yang, Xiulun; Wang, Yurong; Li, Xianye; Peng, Xiang; He, Wenqi; Dong, Guoyan; Chen, Hongyi

    2018-01-01

    A two-level image authentication method is proposed; the method is based on two-step phase-shifting interferometry, double random phase encoding, and compressive sensing (CS) theory, by which the certification image can be encoded into two interferograms. Through discrete wavelet transform (DWT), sparseness processing, Arnold transform, and data compression, two compressed signals can be generated and delivered to two different participants of the authentication system. Only the participant who possesses the first compressed signal attempts to pass the low-level authentication. The application of Orthogonal Match Pursuit CS algorithm reconstruction, inverse Arnold transform, inverse DWT, two-step phase-shifting wavefront reconstruction, and inverse Fresnel transform can result in the output of a remarkable peak in the central location of the nonlinear correlation coefficient distributions of the recovered image and the standard certification image. Then, the other participant, who possesses the second compressed signal, is authorized to carry out the high-level authentication. Therefore, both compressed signals are collected to reconstruct the original meaningful certification image with a high correlation coefficient. Theoretical analysis and numerical simulations verify the feasibility of the proposed method.

  12. Two-Step Single Slope/SAR ADC with Error Correction for CMOS Image Sensor

    Directory of Open Access Journals (Sweden)

    Fang Tang

    2014-01-01

    Full Text Available Conventional two-step ADC for CMOS image sensor requires full resolution noise performance in the first stage single slope ADC, leading to high power consumption and large chip area. This paper presents an 11-bit two-step single slope/successive approximation register (SAR ADC scheme for CMOS image sensor applications. The first stage single slope ADC generates a 3-bit data and 1 redundant bit. The redundant bit is combined with the following 8-bit SAR ADC output code using a proposed error correction algorithm. Instead of requiring full resolution noise performance, the first stage single slope circuit of the proposed ADC can tolerate up to 3.125% quantization noise. With the proposed error correction mechanism, the power consumption and chip area of the single slope ADC are significantly reduced. The prototype ADC is fabricated using 0.18 μm CMOS technology. The chip area of the proposed ADC is 7 μm × 500 μm. The measurement results show that the energy efficiency figure-of-merit (FOM of the proposed ADC core is only 125 pJ/sample under 1.4 V power supply and the chip area efficiency is 84 k μm2·cycles/sample.

  13. Novel two-step method to form silk fibroin fibrous hydrogel

    International Nuclear Information System (INIS)

    Ming, Jinfa; Li, Mengmeng; Han, Yuhui; Chen, Ying; Li, Han; Zuo, Baoqi; Pan, Fukui

    2016-01-01

    Hydrogels prepared by silk fibroin solution have been studied. However, mimicking the nanofibrous structures of extracellular matrix for fabricating biomaterials remains a challenge. Here, a novel two-step method was applied to prepare fibrous hydrogels using regenerated silk fibroin solution containing nanofibrils in a range of tens to hundreds of nanometers. When the gelation process of silk solution occurred, it showed a top-down type gel within 30 min. After gelation, silk fibroin fibrous hydrogels exhibited nanofiber network morphology with β-sheet structure. Moreover, the compressive stress and modulus of fibrous hydrogels were 31.9 ± 2.6 and 2.8 ± 0.8 kPa, respectively, which was formed using 2.0 wt.% concentration solutions. In addition, fibrous hydrogels supported BMSCs attachment and proliferation over 12 days. This study provides important insight in the in vitro processing of silk fibroin into useful new materials. - Highlights: • SF fibrous hydrogel was prepared by a novel two-step method. • SF solution containing nanofibrils in a range of tens to hundreds of nanometers was prepared. • Gelation process was top-down type gel with several minutes. • SF fibrous hydrogels exhibited nanofiber network morphology with β-sheet structure. • Fibrous hydrogels had higher compressive stresses superior to porous hydrogels.

  14. Two-step single slope/SAR ADC with error correction for CMOS image sensor.

    Science.gov (United States)

    Tang, Fang; Bermak, Amine; Amira, Abbes; Amor Benammar, Mohieddine; He, Debiao; Zhao, Xiaojin

    2014-01-01

    Conventional two-step ADC for CMOS image sensor requires full resolution noise performance in the first stage single slope ADC, leading to high power consumption and large chip area. This paper presents an 11-bit two-step single slope/successive approximation register (SAR) ADC scheme for CMOS image sensor applications. The first stage single slope ADC generates a 3-bit data and 1 redundant bit. The redundant bit is combined with the following 8-bit SAR ADC output code using a proposed error correction algorithm. Instead of requiring full resolution noise performance, the first stage single slope circuit of the proposed ADC can tolerate up to 3.125% quantization noise. With the proposed error correction mechanism, the power consumption and chip area of the single slope ADC are significantly reduced. The prototype ADC is fabricated using 0.18 μ m CMOS technology. The chip area of the proposed ADC is 7 μ m × 500 μ m. The measurement results show that the energy efficiency figure-of-merit (FOM) of the proposed ADC core is only 125 pJ/sample under 1.4 V power supply and the chip area efficiency is 84 k  μ m(2) · cycles/sample.

  15. Advanced Laser Architecture for Two-Step Laser Tandem Mass Spectrometer

    Science.gov (United States)

    Fahey, Molly E.; Li, Steven X.; Yu, Anthony W.; Getty, Stephanie A.

    2016-01-01

    Future astrobiology missions will focus on planets with significant astrochemical or potential astrobiological features, such as small, primitive bodies and the icy moons of the outer planets that may host diverse organic compounds. These missions require advanced instrument techniques to fully and unambiguously characterize the composition of surface and dust materials. Laser desorptionionization mass spectrometry (LDMS) is an emerging instrument technology for in situ mass analysis of non-volatile sample composition. A recent Goddard LDMS advancement is the two-step laser tandem mass spectrometer (L2MS) instrument to address the need for future flight instrumentation to deconvolve complex organic signatures. The L2MS prototype uses a resonance enhanced multi-photon laser ionization mechanism to selectively detect aromatic species from a more complex sample. By neglecting the aliphatic and inorganic mineral signatures in the two-step mass spectrum, the L2MS approach can provide both mass assignments and clues to structural information for an in situ investigation of non-volatile sample composition. In this paper we will describe our development effort on a new laser architecture that is based on the previously flown Lunar Orbiter Laser Altimeter (LOLA) laser transmitter for the L2MS instrument. The laser provides two discrete midinfrared wavelengths (2.8 m and 3.4 m) using monolithic optical parametric oscillators and ultraviolet (UV) wavelength (266 nm) on a single laser bench with a straightforward development path toward flight readiness.

  16. Two-Step Electrochemical Intercalation and Oxidation of Graphite for the Mass Production of Graphene Oxide.

    Science.gov (United States)

    Cao, Jianyun; He, Pei; Mohammed, Mahdi A; Zhao, Xin; Young, Robert J; Derby, Brian; Kinloch, Ian A; Dryfe, Robert A W

    2017-12-06

    Conventional chemical oxidation routes for the production of graphene oxide (GO), such as the Hummers' method, suffer from environmental and safety issues due to their use of hazardous and explosive chemicals. These issues are addressed by electrochemical oxidation methods, but such approaches typically have a low yield due to inhomogeneous oxidation. Herein we report a two-step electrochemical intercalation and oxidation approach to produce GO on the large laboratory scale (tens of grams) comprising (1) forming a stage 1 graphite intercalation compound (GIC) in concentrated sulfuric acid and (2) oxidizing and exfoliating the stage 1 GIC in an aqueous solution of 0.1 M ammonium sulfate. This two-step approach leads to GO with a high yield (>70 wt %), good quality (>90%, monolayer), and reasonable oxygen content (17.7 at. %). Moreover, the as-produced GO can be subsequently deeply reduced (3.2 at. % oxygen; C/O ratio 30.2) to yield highly conductive (54 600 S m -1 ) reduced GO. Electrochemical capacitors based on the reduced GO showed an ultrahigh rate capability of up to 10 V s -1 due to this high conductivity.

  17. Practical Engineering Aspects of Catalysis in Microreactors

    Czech Academy of Sciences Publication Activity Database

    Křišťál, Jiří; Stavárek, Petr; Vajglová, Zuzana; Vondráčková, Magdalena; Pavlorková, Jana; Jiřičný, Vladimír

    2015-01-01

    Roč. 41, č. 12 (2015), s. 9357-9371 ISSN 0922-6168. [Pannonian Symposium on Catalysis /12./. Castle Trest, 16.09.2014-20.09.2014] Institutional support: RVO:67985858 Keywords : heterogeneous catalysis * homogeneous catalysis * photo catalysis Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.833, year: 2015

  18. Magnetic catalysis and inverse magnetic catalysis in QCD

    International Nuclear Information System (INIS)

    Mueller, N.

    2015-01-01

    We investigate the effects of strong magnetic fields on the QCD phase structure at vanishing density by solving the gluon and quark gap equations. The chiral crossover temperature as well as the chiral condensate is computed. For asymptotically large magnetic fields we find magnetic catalysis, while we find inverse magnetic catalysis for intermediate magnetic fields. Moreover, for large magnetic fields the chiral phase transition for massless quarks turns into a crossover. The underlying mechanisms are then investigated analytically within a few simplifications of the full numerical analysis. We find that a combination of gluon screening effects and the weakening of the strong coupling is responsible for the phenomenon of inverse catalysis seen in lattice studies. In turn, the magnetic catalysis at large magnetic field is already indicated by simple arguments based on dimensionality. (author)

  19. Thermomyces lanuginosus lipase-catalyzed synthesis of natural flavor esters in a continuous flow microreactor

    OpenAIRE

    Gumel, Ahmad Mohammed; Annuar, M. S. M.

    2016-01-01

    Enzymatic catalysis is considered to be among the most environmental friendly processes for the synthesis of fine chemicals. In this study, lipase from Thermomyces lanuginosus (Lecitase Ultra?) was used to catalyze the synthesis of flavor esters, i.e., methyl butanoate and methyl benzoate by esterification of the acids with methanol in a microfluidic system. Maximum reaction rates of 195 and 115?mM?min?1 corresponding to catalytic efficiencies (k cat/K M) of 0.30 and 0.24?min?1?mM?1 as well a...

  20. Preparation of Layered Double Hydroxide-Immobilized Lipase for High Yield and Optically Active (-)-Menthyl butyrate

    Institute of Scientific and Technical Information of China (English)

    Siti; Salhah; Othman; Mahiran; Basri; Mohd.Zobir; Hussein; Mohd; Basyaruddin; Abdul; Rahman; Raja; Noor; Zaliha; Raja; Abdul; Rahman; Abu; Bakar; Salleh; Salina; Mat; Radzi; Azwani; Sofia; Ahmad; Khiar

    2007-01-01

    1 Results Layered Double Hydroxide (LDH) finds extensive usage in the areas of pharmaceutical sciences and catalysis. In this study, a member of the LDH family, Mg/Al-hydrotalcite (HT), or the so-called anionic clay, was prepared at ratio 4 (HT) by co-precipitating through continuous agitation. X-ray diffraction pattern and thermogravimetric analysis of the material indicated that a pure HT had been successfully synthesized. This matrix was then used as support in the immobilization of lipase from Cand...

  1. Comparison of single-entry and double-entry two-step couple screening for cystic fibrosis carriers

    NARCIS (Netherlands)

    tenKate, LP; Verheij, JBGM; Wildhagen, MF; Hilderink, HBM; Kooij, L; Verzijl, JG; Habbema, JDF

    1996-01-01

    Both single-entry two-step (SETS) couple screening and double-entry two-step (DETS) couple screening have been recommended as methods to screen for cystic fibrosis gene carriers. In this paper we compare the expected results from both types of screening. In general, DETS results in a higher

  2. Two-step calibration method for multi-algorithm score-based face recognition systems by minimizing discrimination loss

    NARCIS (Netherlands)

    Susyanto, N.; Veldhuis, R.N.J.; Spreeuwers, L.J.; Klaassen, C.A.J.; Fierrez, J.; Li, S.Z.; Ross, A.; Veldhuis, R.; Alonso-Fernandez, F.; Bigun, J.

    2016-01-01

    We propose a new method for combining multi-algorithm score-based face recognition systems, which we call the two-step calibration method. Typically, algorithms for face recognition systems produce dependent scores. The two-step method is based on parametric copulas to handle this dependence. Its

  3. Lipase Test: MedlinePlus Lab Test Information

    Science.gov (United States)

    ... page: https://medlineplus.gov/labtests/lipasetest.html Lipase Test To use the sharing features on this page, please enable JavaScript. What is a lipase test? Lipase is a type of protein made by ...

  4. Design, fabrication and characterization of a two-step released silicon dioxide piezoresistive microcantilever immunosensor

    International Nuclear Information System (INIS)

    Zhou, Youzheng; Wang, Zheyao; Wang, Chaonan; Ruan, Wenzhou; Liu, Litian

    2009-01-01

    This paper presents the design, fabrication and characterization of a silicon dioxide piezoresistive microcantilever immunosensor fabricated on silicon-on-insulator (SOI) wafers. The microcantilever consists of two strips of single crystalline silicon piezoresistors sandwiched in between two silicon dioxide layers. A theoretical model for the laminated microcantilever with a discontinuous layer is deduced using classic laminated beam theory. A two-step release method combining anisotropic and isotropic etching is developed to suspend the microcantilever, and the fabrication results show an excellent yield. The residual stress-induced free bending of the microcantilever and the stress caused by self-heating of the piezoresistors are discussed. The microcantilever sensor is characterized as an immunosensor using specific binding of antigen and antibody. These methods and some conclusions are also applicable to the development of other piezoresistive sensors that use laminated structures

  5. Fabrication of porous anodic alumina films by using two-step anodization process

    International Nuclear Information System (INIS)

    Xu Zhan; Zhou Bin; Xu Xiang; Wang Xiaoli; Wu Di; Shen Jun

    2006-01-01

    This article introduces the fabrication of the porous anodic alumina films which have ordered pore arrangement by using a two-step anodization process. The films have a parallel channel structure which nanopore diameter can be 20-100 nm, and depth can reach 50 μm. The change of pore structure in the first and second anodization, moving the alumina layer, widening process was analysed. The effect of the parameters such as different electrolytes, anodization temperature and the voltage on the nanopore structure was studied. The surface and profile structure through FE-SEM (field emission scanning electron microscope), the element composition in tiny area of the anodic aluminum oxide (AAO) surface were studied. The result indicates the pore diameter of AAO which is anodized in oxalic acid solution is larger than which anodized in sulfuric acid solution. The anodization temperature and voltage can enlarge the nanopore diameter of AAO in a range. (authors)

  6. Distribution of photon strength in nuclei by a method of two-step cascades

    International Nuclear Information System (INIS)

    Becvar, F.; Cejnar, P.; Kopecky, J.

    1990-01-01

    The applicability of sum-coincidence measurements of two-step cascade γ-ray spectra to the determination of photon strength functions at intermediate γ-ray energies (3 or 4 MeV) is discussed. An experiment based on thermal neutron capture in Nd was undertaken at the Brookhaven National Laboratory High Flux Beam Reactor to test this model. To understand the role of various uncertainties in similar experiments a series of model calculations was performed. We present an analysis of our experimental data which demonstrates the high sensitivity of the method to E1 and M1 photon strength functions. Our experimental data are in sharp contradiction to those expected from an E1 photon strength distributed according to the classical Lorentzian form with an energy invariant damping width. An alternative distribution of Kadmenskij et al., which violates Brink's Hypothesis, is strongly preferred. 13 refs., 5 figs

  7. Two-step superconducting transition in Cu-V-Si alloys

    International Nuclear Information System (INIS)

    Sharma, R.G.; Krishna, M.M.; Narlikar, A.V.

    1980-01-01

    Copper ternary alloys containing small amounts of vanadium and silicon exhibit a two-step superconducting resistive transition. The first transition occurs around 17 K, the transition temperature of β-W V 3 Si, followed by a plateau and a second transition around 10 K. The resistivity, however, does not drop to zero down to 2.5 K. Reduction of the wire diameter causes the two transitions to shift to lower temperatures. Complete superconductivity in these specimens is absent for two reasons. Firstly, the superconducting volume fraction present in these alloy-wires is below the threshold given by either the effective-medium theory or the site percolation theory. Secondly, the superconducting phase V 3 Si does not precipitate in copper matrix in a fine structure and the proximity effect does not operate strongly. Annealing causes the superconducting particles to coalesce and grow in size and suppresses the proximity effect and superconductivity further in these alloy wires. (author)

  8. Reconstituted NALP1 inflammasome reveals two-step mechanism of caspase-1 activation.

    Science.gov (United States)

    Faustin, Benjamin; Lartigue, Lydia; Bruey, Jean-Marie; Luciano, Frederic; Sergienko, Eduard; Bailly-Maitre, Beatrice; Volkmann, Niels; Hanein, Dorit; Rouiller, Isabelle; Reed, John C

    2007-03-09

    Interleukin (IL)-1beta maturation is accomplished by caspase-1-mediated proteolysis, an essential element of innate immunity. NLRs constitute a recently recognized family of caspase-1-activating proteins, which contain a nucleotide-binding oligomerization domain and leucine-rich repeat (LRR) domains and which assemble into multiprotein complexes to create caspase-1-activating platforms called "inflammasomes." Using purified recombinant proteins, we have reconstituted the NALP1 inflammasome and have characterized the requirements for inflammasome assembly and caspase-1 activation. Oligomerization of NALP1 and activation of caspase-1 occur via a two-step mechanism, requiring microbial product, muramyl-dipeptide, a component of peptidoglycan, followed by ribonucleoside triphosphates. Caspase-1 activation by NALP1 does not require but is enhanced by adaptor protein ASC. The findings provide the biochemical basis for understanding how inflammasome assembly and function are regulated, and shed light on NALP1 as a direct sensor of bacterial components in host defense against pathogens.

  9. A two-step superplastic forging forming of semi-continuously cast AZ70 magnesium alloy

    Directory of Open Access Journals (Sweden)

    Pan Wang

    2015-03-01

    Full Text Available A two-step technology combined forging with superplastic forming has been developed to enhance the forgeability of semi-continuously cast AZ70 magnesium alloy and realize the application of the as-cast magnesium alloy in large deformation bullet shell. In the first step, fine-grained microstructure preforms that are suitable for superplastic forming were obtained by reasonably designing the size of the initial blanks with the specific height-to-diameter ratio, upsetting the blanks and subsequent annealing. In the second step, the heat treated preforms were forged into the end products at the superplastic conditions. The end products exhibit high quality surface and satisfied microstructure. Consequently, this forming technology that not only avoids complicating the material preparation but also utilizes higher strain rate superplastic provides a near net-shaped novel method on magnesium forging forming technology using as-cast billet.

  10. Two-step freezing of hybridoma cells in 96-well microculture plates.

    Science.gov (United States)

    Pĕknicová, J; Kristofová, H

    1985-01-01

    Stabile hybridoma cells, colonies of hybridoma cells 14 days after fusion of immune spleen and myeloma cells, myeloma cells and fibroblasts cultured in 96-well microculture plates were frozen by the method of two-step freezing. The culture medium was aspirated, and 50 microliter of the medium containing a cryoprotectant (5% dimethyl sulphoxide) was added for 10 min at room temperature. The plates were put into microtene bags, placed at -25 degrees C in a freezer for 30 min and then stored at -100 degrees C in liquid nitrogen vapour. Plates with cells were thawed rapidly in a 50 degree C water bath. After thawing the hybrid cells were viable and continued to produce the specific antibody.

  11. Process Mining: A Two-Step Approach to Balance Between Underfitting and Overfitting

    DEFF Research Database (Denmark)

    van der Aalst, W.M.P.; Rubin, V.; Verbeek, H.M.W.

    behavior. At best, one has seen a representative subset. Therefore, classical synthesis techniques are not suitable as they aim at finding a model that is able to exactly reproduce the log. Existing process mining techniques try to avoid such "overfitting" by generalizing the model to allow for more...... behavior. This generalization is often driven by the representation language and very crude assumptions about completeness. As a result, parts of the model are "overfitting" (allow only what has actually been observed) while other parts may be "underfitting" (allow for much more behavior without strong...... support for it). None of the existing techniques enables the user to control the balance between "overfitting" and "underfitting". To address this, we propose a two-step approach. First, using a configurable approach, a transition system is constructed. Then, using the "theory of regions", the model...

  12. Two-step optimization of pressure and recovery of reverse osmosis desalination process.

    Science.gov (United States)

    Liang, Shuang; Liu, Cui; Song, Lianfa

    2009-05-01

    Driving pressure and recovery are two primary design variables of a reverse osmosis process that largely determine the total cost of seawater and brackish water desalination. A two-step optimization procedure was developed in this paper to determine the values of driving pressure and recovery that minimize the total cost of RO desalination. It was demonstrated that the optimal net driving pressure is solely determined by the electricity price and the membrane price index, which is a lumped parameter to collectively reflect membrane price, resistance, and service time. On the other hand, the optimal recovery is determined by the electricity price, initial osmotic pressure, and costs for pretreatment of raw water and handling of retentate. Concise equations were derived for the optimal net driving pressure and recovery. The dependences of the optimal net driving pressure and recovery on the electricity price, membrane price, and costs for raw water pretreatment and retentate handling were discussed.

  13. Smart Wireless Power Transfer Operated by Time-Modulated Arrays via a Two-Step Procedure

    Directory of Open Access Journals (Sweden)

    Diego Masotti

    2015-01-01

    Full Text Available The paper introduces a novel method for agile and precise wireless power transmission operated by a time-modulated array. The unique, almost real-time reconfiguration capability of these arrays is fully exploited by a two-step procedure: first, a two-element time-modulated subarray is used for localization of tagged sensors to be energized; the entire 16-element TMA then provides the power to the detected tags, by exploiting the fundamental and first-sideband harmonic radiation. An investigation on the best array architecture is carried out, showing the importance of the adopted nonlinear/full-wave computer-aided-design platform. Very promising simulated energy transfer performance of the entire nonlinear radiating system is demonstrated.

  14. Two-step frequency conversion for connecting distant quantum memories by transmission through an optical fiber

    Science.gov (United States)

    Tamura, Shuhei; Ikeda, Kohei; Okamura, Kotaro; Yoshii, Kazumichi; Hong, Feng-Lei; Horikiri, Tomoyuki; Kosaka, Hideo

    2018-06-01

    Long-distance quantum communication requires entanglement between distant quantum memories. For this purpose, photon transmission is necessary to connect the distant memories. Here, for the first time, we develop a two-step frequency conversion process (from a visible wavelength to a telecommunication wavelength and back) involving the use of independent two-frequency conversion media where the target quantum memories are nitrogen-vacancy centers in diamonds (with an emission/absorption wavelength of 637.2 nm), and experimentally characterize the performance of this process acting on light from an attenuated CW laser. A total conversion efficiency of approximately 7% is achieved. The noise generated in the frequency conversion processes is measured, and the signal-to-noise ratio is estimated for a single photon signal emitted by a nitrogen-vacancy (NV) center. The developed frequency conversion system has future applications via transmission through a long optical fiber channel at a telecommunication wavelength for a quantum repeater network.

  15. A two-step obtainment of quantum confinement in ZnO nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Mofor, A C; El-Shaer, A; Suleiman, M; Bakin, A; Waag, A [Institute of Semiconductor Technology, Technical University Braunschweig, Hans-Sommer-Strasse 66, D-38106 Braunschweig (Germany)

    2006-10-14

    ZnO nanorod-based single quantum well heterostructures were fabricated in a two-step process. Nanorods were first grown using vapour transport. Subsequently, high-quality ZnO/Zn{sub 0.85}Mg{sub 0.15}O heterostructures were grown on the nanorods using molecular beam epitaxy. The nanorods are well aligned along the c-axis of ZnO, as indicated by a very narrow rocking curve full width at half maximum. Quantum confinement was clearly observed within the ZnO well for different well widths. The quantum wells show photoluminescence peaks with a full width at half maximum as small as 15 meV.

  16. A new two-step tuning procedure for a photocathode gun

    International Nuclear Information System (INIS)

    Lal, Shankar; Pant, K.K.; Krishnagopal, S.

    2008-01-01

    An important aspect of the development of multi-cell RF accelerating structures is tuning the resonant frequency f of the operating mode, field balance e b , and waveguide to cavity coupling coefficient β to the desired values. Earlier theoretical analyses have not been able to predict all three parameters simultaneously for a coupled-cavity system. We have developed a generalized circuit analysis to predict f, e b , and β of a coupled structure, based on the RF properties of the individual, uncoupled, cells. This has been used to develop a simplified two-step tuning procedure to tune a BNL/SLAC/UCLA type 1.6 cell S-band photocathode gun by varying RF properties of individual half and full cells, which are easily measurable. This procedure has been validated by tuning two true-to-scale prototypes made of aluminum and ETP copper to the desired values of the RF parameters

  17. Synthesis of highly ordered nanopores on alumina by two-step anodization process

    Energy Technology Data Exchange (ETDEWEB)

    Bwana, Nicholas N. [University of Oxford, Department of Engineering Science (United Kingdom)], E-mail: Nicholas.Bwana@eng.ox.ac.uk

    2008-02-15

    Highly ordered anodic alumina was produced, on RF sputtered aluminium on a conductive glass substrate, by two step anodizing process in 0.4 M sulphuric acid at constant cell potentials of between 5 and 25 V and at a constant current density of 20 mA cm{sup -2}. The temperature was kept constant at 15 deg. C during both anodization processes. The effects of the anodizing potential, current density, and time on the pore diameters were established. Longer anodization periods result in wider irregular pores with reduced porosity for both constant potential and constant current density anodization processes. The current density increases with increasing constant anodizing potential and generally remains constant with time after a sharp rise. Potential drop during constant current density anodization behaves in a similar manner. We confirm that sulphuric acid has a self-ordering potential of 25 V above which burning occurs.

  18. A Two-Step Theory of the Evolution of Human Thinking

    Directory of Open Access Journals (Sweden)

    Satne Glenda

    2016-03-01

    Full Text Available Social accounts of objective content, like the one advanced by Tomasello (2014, are traditionally challenged by an ‘essential tension’ (Hutto and Satne 2015. The tension is the following: while sociality is deemed to be at the basis of thinking, in order to explain sociality, some form of thinking seems to be necessarily presupposed. In this contribution I analyse Tomasello’s two-step theory of the evolution of human thinking vis-à-vis this challenge. While his theory is in principle suited to address it, I claim that the specifics of the first step and the notion of perspective that infuse it are problematic in this regard. I end by briefly sketching an alternative.

  19. Two-Step Classification of Unemployed People in the Czech Republic

    Directory of Open Access Journals (Sweden)

    Zdeněk Šulc

    2015-03-01

    Full Text Available The paper analyzes structure and behavior of unemployed people in the Czech Republic by means of latent class analysis (LCA and CHAID analysis where the output of LCA serves as the input for CHAID. The unemployed are classified in two steps; for each step different characteristics are used. In the first step, respondents are split into latent classes according to their answers to questions concerning ways of searching for a new job. In the second step, CHAID analysis is performed with results obtained from LCA as a dependent variable. In the paper, data from periodical Labor Force Survey conducted in Czech Republic in spring 2011 are used. The results indicate that unemployed people in the Czech Republic can be divided into four segments: Active, Passive, Typical and Specific. A special attention is paid to extreme segments Active and Passive.

  20. Microstructural and electrical properties of cordierite-based ceramics obtained after two-step sintering technique

    Directory of Open Access Journals (Sweden)

    Obradović Nina

    2016-01-01

    Full Text Available Cordierite-based ceramic materials are attracting much interest for their various applications in industry, for manufacturing multilayer circuit boards, catalytic converters, filters, thermal insulation, kiln furniture, components of portable electronic devices, etc. In order to reduce production costs and modify cordierite-based materials, mechanical activation can be used. In this study, microstructural and electrical properties of mechanically activated MgO-Al2O3-SiO2 system have been analyzed. The mixtures of MgO-Al2O3-SiO2 powders were mechanically activated in a planetary ball mill for the time periods from 0 to 160 min. Morphological investigations have been performed on the obtained powders. The effects of activation and two-step sintering process on microstructure were investigated by scanning electron microscopy (SEM. Electrical measurements showed variations of the dielectric constant (εr and loss tangent (tan δ as a function of time of mechanical treatment.

  1. Novel two-step synthesis of gold nanoparticles capped with bile acid conjugates

    International Nuclear Information System (INIS)

    Noponen, Virpi; Bhat, Shreedhar; Sievaenen, Elina; Kolehmainen, Erkki

    2008-01-01

    Bile acids and their conjugates are physiologically important molecules. Syntheses and structure elucidation combined with investigation of properties and applications of bile acids and their derivatives are of academic interest. The concept of using bile acids and their conjugates in nanoscience is a novel idea, which opens up fascinating prospects. In this article, an easy and simple route for obtaining N-lithocholyl-L-(cysteine ethyl ester) (3), capable of effectively capping and stabilizing metal nanoparticles, is described. The whole synthetic route needs only two steps giving a moderate to good yield. The gold NPs are characterized by elemental analysis, UV spectroscopy, and TEM. Additionally, 13 C CP/MAS NMR studies for different ligand/Au ratios have been performed

  2. A re-examination of two-step lateral stress history in silicon carbide

    International Nuclear Information System (INIS)

    Dandekar, Dattatraya P.

    2004-01-01

    The observed two-step lateral stress history in silicon carbide, SiC-B under plane shock wave propagation [N. K. Bourne, J. Millett, and I. Pickup, J. Appl. Phys. 81, 6019 (1997)] is attributed to a delayed failure in SiC-B due to propagation of a slow moving front traveling behind the main shock wave. According to this attribution, the first lower magnitude, step corresponds to the lateral stress in intact shock compressed silicon carbide as a result of the fast moving plane shock wave. The second step of higher magnitude, observed after a few hundred nanoseconds, corresponds to the lateral stress in failed silicon carbide due to propagation of the slower moving front. The current analysis, takes into account additional relevant existing results dealing with shock response of SiC-B, and shows that the suggested explanation for the observed phenomenon remains in doubt

  3. Two-centre interference effects on the Thomas two-step scattering mechanisms

    International Nuclear Information System (INIS)

    Adivi, E Ghanbari

    2010-01-01

    The charge transfer process in the collision of fast protons with hydrogen molecules is theoretically investigated using the second-order Born approximation with correct boundary conditions. In addition to two first-order terms, the present calculations include the three second-order terms which correspond to the Thomas two-step scattering mechanisms. The interference effects, due to the scattering of the particles from two atomic centres, on the electron capture differential cross sections vary significantly with the orientation of the molecule and with the impact energy. After the averaging over all molecular orientations the interference patterns disappear but the Thomas peak becomes more pronounced. These patterns are also apparent in the differential cross sections as a function of the angle between the molecular axis and the incident beam direction. The integrated cross sections are calculated and the results are compared with available experimental data.

  4. Characteristic analysis of laser isotope separation process by two-step photodissociation method

    International Nuclear Information System (INIS)

    Okamoto, Tsuyoshi; Suzuki, Atsuyuki; Kiyose, Ryohei

    1981-01-01

    A large number of laser isotope separation experiments have been performed actively in many countries. In this paper, the selective two-step photodissociation method is chosen and simultaneous nonlinear differential equations that express the separation process are solved directly by using computer. Predicted separation factors are investigated in relation to the incident pulse energy and the concentration of desired molecules. Furthermore, the concept of separative work is used to evaluate the results of separation for this method. It is shown from an example of numerical calculation that a very large separation factor can be obtained if the concentration of desired molecules is lowered and two laser pulses to be closely synchronized are not always required in operation for the photodissociation of molecules. (author)

  5. Unusual inferior dislocation of shoulder: reduction by two-step maneuver: a case report

    Directory of Open Access Journals (Sweden)

    Patro Dilip K

    2009-11-01

    Full Text Available Abstract Dislocation of the shoulder is the commonest of all large joint dislocations. Inferior dislocation constitutes 0.5% of all shoulder dislocations. It characteristically presents with overhead abduction of the arm, the humerus being parallel to the spine of scapula. We present an unusual case of recurrent luxatio erecta in which the arm transformed later into an adducted position resembling the more common anterior shoulder dislocation. Such a case has not been described before in English literature. Closed reduction by the two-step maneuver was successful with a single attempt. MRI revealed posterior labral tear and a Hill-Sachs variant lesion on the superolateral aspect of humeral head. Immobilisation in a chest-arm bandage followed by physiotherapy yielded excellent results. The case is first of its kind; the unusual mechanism, unique radiological findings and alternate method of treatment are discussed.

  6. SiO2 sol-gel films after ammonia and heat two-step treatments

    International Nuclear Information System (INIS)

    Zhang Chunlai; Wang Biyi; Tian Dongbin; Yin Wei; Jiang Xiaodong; Yuan Xiaodong; Yan Lianghong; Zhang Hongliang; Zhao Songnan; Lv Haibing

    2008-01-01

    SiO 2 thin films were deposited using tetraethoxylsilane as precursor, ammonia as catalyst on K9 glass by sol-gel method. These films were post-treated by ammonia and heat. The properties of the coatings were characterized by ellipsometer, UV-vis spectrophotometry, FTIR-spectroscopy, scanning probe microscope and contact angle measurement apparatus. The resuits indicate that the thickness of the films with ammonia and heat treatment tend to decrease. Both the refractive index and water contact angle increase after ammonia treatment. However, they both decrease after heat treatment. The former increases by 0.236 for the first step, then decreases by 0.202 for the second. The latter increases to 58.92 degree, then decreases to 38.07 degree. The transmittance of the coatings turn to be better and continuously shift to short wave by UV-vis spectrophotometry. The surface becomes smoother by AFM after the two-step treatment. (authors)

  7. Two-step controllable electrochemical etching of tungsten scanning probe microscopy tips

    KAUST Repository

    Khan, Yasser; Al-Falih, Hisham; Ng, Tien Khee; Ooi, Boon S.; Zhang, Yaping

    2012-01-01

    Dynamic electrochemical etching technique is optimized to produce tungsten tips with controllable shape and radius of curvature of less than 10 nm. Nascent features such as dynamic electrochemical etching and reverse biasing after drop-off are utilized, and two-step dynamic electrochemical etching is introduced to produce extremely sharp tips with controllable aspect ratio. Electronic current shut-off time for conventional dc drop-off technique is reduced to ?36 ns using high speed analog electronics. Undesirable variability in tip shape, which is innate to static dc electrochemical etching, is mitigated with novel dynamic electrochemical etching. Overall, we present a facile and robust approach, whereby using a novel etchant level adjustment mechanism, 30° variability in cone angle and 1.5 mm controllability in cone length were achieved, while routinely producing ultra-sharp probes. © 2012 American Institute of Physics.

  8. Low temperature synthesis of nano alpha-alumina powder by two-step hydrolysis

    International Nuclear Information System (INIS)

    Yan, Ting; Guo, Xiaode; Zhang, Xiang; Wang, Zhixiang; Shi, Jinqiu

    2016-01-01

    Highlights: • The nano α-Al 2 O 3 with good dispersion was prepared by two-step hydrolysis. • α-Al 2 O 3 powders were added as seed particles in the hydrolysis. • This article indicated that the glucose could impel the γ-Al 2 O 3 transformed to α-Al 2 O 3 directly. • This article indicated that the addictive of α-Al 2 O 3 seed could improve the phase transformation rate of γ-Al 2 O 3 to α-Al 2 O 3 . • In this article, the pure α-Al 2 O 3 could be obtained by calcining at 1000 °C for 1.5 h. - Abstract: The ultral fine alpha-alumina powder has been successfully synthesized via two-step hydrolysis of aluminum isopropoxide. Glucose and polyvinyl pyrrolidone were used as surfactants during the appropriate processing step. The alpha-alumina powder was used as seed particles. Several synthesis parameters, such as the amount of seeds, surfactants, and calcination temperature, were studied by X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), Thermogravimetry-differential scanning calorimetry (TG-DSC), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The experimental results showed that glucose greatly lower the phase transformation temperature of alpha-alumina by impelling the gamma-alumina transformed to alpha-alumina directly, and the seed could improve the phase transformation rate of alpha-alumina, the polyvinylpyrrolidone have an effect on preventing excessive grain growth and agglomeration of alpha-alumina powder. Comparatively well dispersed alpha-alumina powder with particle size less than 50 nm can be synthesized through this method after calcinations at 1000 °C for 2 h.

  9. FAN-SPINE TOPOLOGY FORMATION THROUGH TWO-STEP RECONNECTION DRIVEN BY TWISTED FLUX EMERGENCE

    International Nuclear Information System (INIS)

    Toeroek, T.; Aulanier, G.; Schmieder, B.; Reeves, K. K.; Golub, L.

    2009-01-01

    We address the formation of three-dimensional nullpoint topologies in the solar corona by combining Hinode/X-ray Telescope (XRT) observations of a small dynamic limb event, which occurred beside a non-erupting prominence cavity, with a three-dimensional (3D) zero-β magnetohydrodynamics (MHD) simulation. To this end, we model the boundary-driven 'kinematic' emergence of a compact, intense, and uniformly twisted flux tube into a potential field arcade that overlies a weakly twisted coronal flux rope. The expansion of the emerging flux in the corona gives rise to the formation of a nullpoint at the interface of the emerging and the pre-existing fields. We unveil a two-step reconnection process at the nullpoint that eventually yields the formation of a broad 3D fan-spine configuration above the emerging bipole. The first reconnection involves emerging fields and a set of large-scale arcade field lines. It results in the launch of a torsional MHD wave that propagates along the arcades, and in the formation of a sheared loop system on one side of the emerging flux. The second reconnection occurs between these newly formed loops and remote arcade fields, and yields the formation of a second loop system on the opposite side of the emerging flux. The two loop systems collectively display an anenome pattern that is located below the fan surface. The flux that surrounds the inner spine field line of the nullpoint retains a fraction of the emerged twist, while the remaining twist is evacuated along the reconnected arcades. The nature and timing of the features which occur in the simulation do qualititatively reproduce those observed by XRT in the particular event studied in this paper. Moreover, the two-step reconnection process suggests a new consistent and generic model for the formation of anemone regions in the solar corona.

  10. [Deep alkali burns: Evaluation of a two-step surgical strategy].

    Science.gov (United States)

    Devinck, F; Deveaux, C; Bennis, Y; Deken-Delannoy, V; Jeanne, M; Martinot-Duquennoy, V; Guerreschi, P; Pasquesoone, L

    2018-04-10

    Chemical burns are rare but often lead to deep cutaneous lesions. Alkali agents have a deep and long lasting penetrating power, causing burns that evolve over several days. The local treatment for these patients is excision of the wound and split thickness skin graft. Early excision and immediate skin grafting of alkali burns are more likely to be complicated by graft failure and delayed wound healing. We propose a two-step method that delays skin grafting until two-three days after burn wound excision. Our population included 25 controls and 16 cases. Men were predominant with a mean age of 41.9 years. In 78% of cases, burns were located on the lower limbs. The mean delay between the burn and excision was 16.5 days. In cases, the skin graft was performed at a mean of 11.3 days after the initial excision. We did not unveil any significant difference between both groups for the total skin surface affected, topography of the burns and the causal agent. Wound healing was significantly shorter in cases vs controls (37.5 days vs 50.3 days; P<0.025). Furthermore, we observed a decreased number of graft failures in cases vs controls (13.3% vs 46.7%; P=0.059). Our study shows the relevance of a two-step surgical strategy in patients with alkali chemical burns. Early excision followed by interval skin grafting is associated with quicker wound healing and decreased rate of graft failure. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

  11. Lipase H, a new member of the triglyceride lipase family synthesized by the intestine

    NARCIS (Netherlands)

    Jin, Weijun; Broedl, Uli C.; Monajemi, Houshang; Glick, Jane M.; Rader, Daniel J.

    2002-01-01

    We report here the molecular cloning of a novel member of the triglyceride lipase family, a 2.4-kb cDNA encoding human lipase H (LIPH) and the mouse ortholog (Liph). The human LIPH cDNA encodes a 451-amino-acid protein with a lipase domain. Mouse Liph shows 85% amino acid identity and 75% nucleotide

  12. Structure and Function of Lipase

    DEFF Research Database (Denmark)

    Skjold-Jørgensen, Jakob

    .e. the waterlipidinterface. For Thermomyces lanuginosus lipase (TlL) and related lipases, activation of the enzymeinvolves a rearrangement of a structural domain, called the “lid”, which covers the active site inhomogenous aqueous solution. At the water-lipid interface, the lid is displaced from the active site andmoves...... the water-lipid interface, structural movements occurring during activation have been difficult to probeexperimentally. In this work, novel variants of TlL were constructed based on rational design with amutated lid-region in order to elucidate the impact of the lid-residue composition and characteristics...... onthe activation mechanism. From characterization studies of these variants we have shown (Paper I) thatthe lid-region plays a crucial role in governing interfacial activation and enzymatic activity. Specifically,using a combination of spectroscopic and enzymatic activity-based methods we have...

  13. Spectroscopy in catalysis : an introduction

    NARCIS (Netherlands)

    Niemantsverdriet, J.W.

    2000-01-01

    Spectroscopy in Catalysis describes the most important modern analytical techniques used to investigate catalytic surfaces. These include electron spectroscopy (XPS, UPS, AES, EELS), ion spectroscopy (SIMS, SNMS, RBS, LEIS), vibrational spectroscopy (infrared, Raman, EELS), temperature-programmed

  14. Editorial: Nanoscience makes catalysis greener

    KAUST Repository

    Polshettiwar, Vivek

    2012-01-09

    Green chemistry by nanocatalysis: Catalysis is a strategic field of science because it involves new ways of meeting energy and sustainability challenges. The concept of green chemistry, which makes the science of catalysis even more creative, has become an integral part of sustainability. This special issue is at the interface of green chemistry and nanocatalysis, and features excellent background articles as well as the latest research results. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. A Nanopore-Structured Nitrogen-Doped Biocarbon Electrocatalyst for Oxygen Reduction from Two-Step Carbonization of Lemna minor Biomass

    Science.gov (United States)

    Guo, Chaozhong; Li, Zhongbin; Niu, Lidan; Liao, Wenli; Sun, Lingtao; Wen, Bixia; Nie, Yunqing; Cheng, Jing; Chen, Changguo

    2016-05-01

    So far, the development of highly active and stable carbon-based electrocatalysts for oxygen reduction reaction (ORR) to replace commercial Pt/C catalyst is a hot topic. In this study, a new nanoporous nitrogen-doped carbon material was facilely designed by two-step pyrolysis of the renewable Lemna minor enriched in crude protein under a nitrogen atmosphere. Electrochemical measurements show that the onset potential for ORR on this carbon material is around 0.93 V (versus reversible hydrogen electrode), slightly lower than that on the Pt/C catalyst, but its cycling stability is higher compared to the Pt/C catalyst in an alkaline medium. Besides, the ORR at this catalyst approaches to a four-electron transfer pathway. The obtained ORR performance can be basically attributed to the formation of high contents of pyridinic and graphitic nitrogen atoms inside this catalyst. Thus, this work opens up the path in the ORR catalysis for the design of nitrogen-doped carbon materials utilizing aquatic plants as starting precursors.

  16. Molecular ingredients of heterogeneous catalysis

    International Nuclear Information System (INIS)

    Somorjai, G.A.

    1982-06-01

    The purpose of this paper is to present a review and status report to those in theoretical chemistry of the rapidly developing surface science of heterogeneous catalysis. The art of catalysis is developing into science. This profound change provides one with opportunities not only to understand the molecular ingredients of important catalytic systems but also to develop new and improved catalyst. The participation of theorists to find answers to important questions is sorely needed for the sound development of the field. It is the authors hope that some of the outstanding problems of heterogeneous catalysis that are identified in this paper will be investigated. For this purpose the paper is divided into several sections. The brief Introduction to the methodology and recent results of the surface science of heterogeneous catalysis is followed by a review of the concepts of heterogeneous catalysis. Then, the experimental results that identified the three molecular ingredients of catalysis, structure, carbonaceous deposit and the oxidation state of surface atoms are described. Each section is closed with a summary and a list of problems that require theoretical and experimental scrutiny. Finally attempts to build new catalyst systems and the theoretical and experimental problems that appeared in the course of this research are described

  17. Molecular ingredients of heterogeneous catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Somorjai, G.A.

    1982-06-01

    The purpose of this paper is to present a review and status report to those in theoretical chemistry of the rapidly developing surface science of heterogeneous catalysis. The art of catalysis is developing into science. This profound change provides one with opportunities not only to understand the molecular ingredients of important catalytic systems but also to develop new and improved catalyst. The participation of theorists to find answers to important questions is sorely needed for the sound development of the field. It is the authors hope that some of the outstanding problems of heterogeneous catalysis that are identified in this paper will be investigated. For this purpose the paper is divided into several sections. The brief Introduction to the methodology and recent results of the surface science of heterogeneous catalysis is followed by a review of the concepts of heterogeneous catalysis. Then, the experimental results that identified the three molecular ingredients of catalysis, structure, carbonaceous deposit and the oxidation state of surface atoms are described. Each section is closed with a summary and a list of problems that require theoretical and experimental scrutiny. Finally attempts to build new catalyst systems and the theoretical and experimental problems that appeared in the course of this research are described.

  18. Enhanced Micellar Catalysis LDRD.

    Energy Technology Data Exchange (ETDEWEB)

    Betty, Rita G.; Tucker, Mark D; Taggart, Gretchen; Kinnan, Mark K.; Glen, Crystal Chanea; Rivera, Danielle; Sanchez, Andres; Alam, Todd Michael

    2012-12-01

    The primary goals of the Enhanced Micellar Catalysis project were to gain an understanding of the micellar environment of DF-200, or similar liquid CBW surfactant-based decontaminants, as well as characterize the aerosolized DF-200 droplet distribution and droplet chemistry under baseline ITW rotary atomization conditions. Micellar characterization of limited surfactant solutions was performed externally through the collection and measurement of Small Angle X-Ray Scattering (SAXS) images and Cryo-Transmission Electron Microscopy (cryo-TEM) images. Micellar characterization was performed externally at the University of Minnesotas Characterization Facility Center, and at the Argonne National Laboratory Advanced Photon Source facility. A micellar diffusion study was conducted internally at Sandia to measure diffusion constants of surfactants over a concentration range, to estimate the effective micelle diameter, to determine the impact of individual components to the micellar environment in solution, and the impact of combined components to surfactant phase behavior. Aerosolized DF-200 sprays were characterized for particle size and distribution and limited chemical composition. Evaporation rates of aerosolized DF-200 sprays were estimated under a set of baseline ITW nozzle test system parameters.

  19. Two-step milling on the carbonyl iron particles and optimizing on the composite absorption

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yonggang, E-mail: xuyonggang221@163.com [Science and Technology on Electromagnetic Scattering Laboratory, Shanghai 200438 (China); Yuan, Liming; Wang, Xiaobing [Science and Technology on Electromagnetic Scattering Laboratory, Shanghai 200438 (China); Zhang, Deyuan [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China)

    2016-08-15

    The flaky carbonyl iron particles (CIPs) were prepared using a two-step milling process. The surface morphology was characterized by the scanning electron microscopy, the static magnetic property was evaluated on a vibrating sample magnetometer and X-ray diffraction (XRD) patterns were done to analyze the particle crystal grain structure. The complex permittivity and permeability were measured using a vector network analyzer in the frequency range of 2–18 GHz. Then Hermite interpolation based on the calculated scattering parameters of the tested composite was used to derive the permittivity and permeability of the composite with random volume content. The results showed that the saturation magnetization value of the flaky CIPs decreased as the CIPs was changed to the flakes by high and low speeding milling. The diffraction peaks of the single α-Fe existed in the XRD pattern of CIPs, and the characteristic peaks was broad and the intensity of the diffraction pattern was lower as the high-speeding milling time increased. The sample H2L20 had the largest particle size, the average diameter was 8.64 μm, the thickness was 0.59 μm according to the fitted aspect ratio 14.65. The derived permittivity and permeability using the Hermite interpolation was accurate compared with the tested result, the deviation was about 0.39 + j0.45 and 2.5 + j0.51. Finally, the genetic algorithm was used to optimize the thickness of the CIPs composite of a wide absorbing band of 8–18 GHz. The optimized reflection loss (RL) result showed that the absorbing composites with thickness 1.47 mm had an excellent absorbing property (RL < −10 dB) in 8–18 GHz. - Graphical abstract: The property of absorber added two speeding milling CIPs could be enhanced using the genetic algorithm. - Highlights: • Flaky CIPs were prepared using a two-step milling process. • The permeability increased during the low speeding milling. • The aspect ratio of flaky CIPs increased in the optimized process

  20. A permeation theory for single-file ion channels: one- and two-step models.

    Science.gov (United States)

    Nelson, Peter Hugo

    2011-04-28

    How many steps are required to model permeation through ion channels? This question is investigated by comparing one- and two-step models of permeation with experiment and MD simulation for the first time. In recent MD simulations, the observed permeation mechanism was identified as resembling a Hodgkin and Keynes knock-on mechanism with one voltage-dependent rate-determining step [Jensen et al., PNAS 107, 5833 (2010)]. These previously published simulation data are fitted to a one-step knock-on model that successfully explains the highly non-Ohmic current-voltage curve observed in the simulation. However, these predictions (and the simulations upon which they are based) are not representative of real channel behavior, which is typically Ohmic at low voltages. A two-step association/dissociation (A/D) model is then compared with experiment for the first time. This two-parameter model is shown to be remarkably consistent with previously published permeation experiments through the MaxiK potassium channel over a wide range of concentrations and positive voltages. The A/D model also provides a first-order explanation of permeation through the Shaker potassium channel, but it does not explain the asymmetry observed experimentally. To address this, a new asymmetric variant of the A/D model is developed using the present theoretical framework. It includes a third parameter that represents the value of the "permeation coordinate" (fractional electric potential energy) corresponding to the triply occupied state n of the channel. This asymmetric A/D model is fitted to published permeation data through the Shaker potassium channel at physiological concentrations, and it successfully predicts qualitative changes in the negative current-voltage data (including a transition to super-Ohmic behavior) based solely on a fit to positive-voltage data (that appear linear). The A/D model appears to be qualitatively consistent with a large group of published MD simulations, but no

  1. Two-Step Forecast of Geomagnetic Storm Using Coronal Mass Ejection and Solar Wind Condition

    Science.gov (United States)

    Kim, R.-S.; Moon, Y.-J.; Gopalswamy, N.; Park, Y.-D.; Kim, Y.-H.

    2014-01-01

    To forecast geomagnetic storms, we had examined initially observed parameters of coronal mass ejections (CMEs) and introduced an empirical storm forecast model in a previous study. Now we suggest a two-step forecast considering not only CME parameters observed in the solar vicinity but also solar wind conditions near Earth to improve the forecast capability. We consider the empirical solar wind criteria derived in this study (Bz = -5 nT or Ey = 3 mV/m for t = 2 h for moderate storms with minimum Dst less than -50 nT) (i.e. Magnetic Field Magnitude, B (sub z) less than or equal to -5 nanoTeslas or duskward Electrical Field, E (sub y) greater than or equal to 3 millivolts per meter for time greater than or equal to 2 hours for moderate storms with Minimum Disturbance Storm Time, Dst less than -50 nanoTeslas) and a Dst model developed by Temerin and Li (2002, 2006) (TL [i.e. Temerin Li] model). Using 55 CME-Dst pairs during 1997 to 2003, our solar wind criteria produce slightly better forecasts for 31 storm events (90 percent) than the forecasts based on the TL model (87 percent). However, the latter produces better forecasts for 24 nonstorm events (88 percent), while the former correctly forecasts only 71 percent of them. We then performed the two-step forecast. The results are as follows: (i) for 15 events that are incorrectly forecasted using CME parameters, 12 cases (80 percent) can be properly predicted based on solar wind conditions; (ii) if we forecast a storm when both CME and solar wind conditions are satisfied (n, i.e. cap operator - the intersection set that is comprised of all the elements that are common to both), the critical success index becomes higher than that from the forecast using CME parameters alone, however, only 25 storm events (81 percent) are correctly forecasted; and (iii) if we forecast a storm when either set of these conditions is satisfied (?, i.e. cup operator - the union set that is comprised of all the elements of either or both

  2. Label-free measurement of the yeast short chain TAG lipase activity by ESI-MS after one-step esterification.

    Science.gov (United States)

    Ham, Hye Jin; Seo, Jongcheol; Yoon, Hye-Joo; Shin, Seung Koo

    2017-03-01

    Triacylglycerol (TAG) lipases hydrolyze ester bonds in TAG and release diacylglycerol (DAG), monoacylglycerol (MAG), and FA. We present a one-step chemical derivatization method for label-free quantification of a mixture of TAG, DAG, and MAG following lipase assay by ESI-MS. Because the ionization efficiencies of TAG, DAG, and MAG are not identical, lipase reaction products, DAG and MAG, are derivatized to TAG species by esterifying their hydroxyl groups using acyl chloride, whose acyl chain contains one less (or one more) -CH 2 group than that of substrate TAG. This resulted in three TAG species that were separated by 14 Da from one another and exhibited similar ion responses representing their molar amounts in the mass spectra. A good linear correlation was observed between peak intensity ratios and molar ratios in calibration curve. This method enables simultaneous quantification of TAG, DAG, and MAG in lipase assay and, in turn, allows stoichiometric determination of the concentrations of FAs released from TAG and DAG separately. By applying this strategy to measure both TAG and DAG lipolytic activities of the yeast Tgl2 lipase, we demonstrated its usefulness in studying enzymatic catalysis, as lipase enzymes often show dissimilar activities toward these lipids. Copyright © 2017 by the American Society for Biochemistry and Molecular Biology, Inc.

  3. Photocatalytically active Au/TiO2 films deposited by two-step spray pyrolysis

    International Nuclear Information System (INIS)

    Balashev, Konstantin; Georgiev, Petar; Simeonova, Sylvia; Stambolova, Irina; Blaskov, Vladimir; Vassilev, Sasho; Eliyas, Alexander

    2016-01-01

    Nanocrystalline TiO 2 and surface gold-modified films (Au/TiO 2 ) are obtained by two step spray pyrolysis process. Titanium tetrachloride (TiCl 4 ) was used as inorganic titanium precursor. The Au nanoparticles were deposited on the surface of sprayed TiO 2 films, obtained by the classical Turkevich method. The AFM analyses have revealed that the roughness of Au/TiO 2 is twice lower than that of the reference titania film. Some globular species are visible on the surface, which could be either individual Au nanoparticles or Au nanoparticles’ agglomerates embedded into the TiO 2 film. The photocatalytic activity in the oxidative degradation of Reactive Black 5 dye under visible light of the Au/TiO 2 films was estimated in a semi-batch reactor. Surface gold modified TiO 2 films revealed higher photocatalytic efficiency than the reference sample. Key words: Au nanoparticles, photocatalysis, azo dye, titania, nanosized

  4. Mother Vocal Recognition in Antarctic Fur Seal Arctocephalus gazella Pups: A Two-Step Process.

    Directory of Open Access Journals (Sweden)

    Thierry Aubin

    Full Text Available In otariids, mother's recognition by pups is essential to their survival since females nurse exclusively their own young and can be very aggressive towards non-kin. Antarctic fur seal, Arctocephalus gazella, come ashore to breed and form dense colonies. During the 4-month lactation period, females alternate foraging trips at sea with suckling period ashore. On each return to the colony, females and pups first use vocalizations to find each other among several hundred conspecifics and olfaction is used as a final check. Such vocal identification has to be highly efficient. In this present study, we investigated the components of the individual vocal signature used by pups to identify their mothers by performing playback experiments on pups with synthetic signals. We thus tested the efficiency of this individual vocal signature by performing propagation tests and by testing pups at different playback distances. Pups use both amplitude and frequency modulations to identify their mother's voice, as well as the energy spectrum. Propagation tests showed that frequency modulations propagated reliably up to 64m, whereas amplitude modulations and spectral content greatly were highly degraded for distances over 8m. Playback on pups at different distances suggested that the individual identification is a two-step process: at long range, pups identified first the frequency modulation pattern of their mother's calls, and other components of the vocal signature at closer range. The individual vocal recognition system developed by Antarctic fur seals is well adapted to face the main constraint of finding kin in a crowd.

  5. Electrohydraulic linear actuator with two stepping motors controlled by overshoot-free algorithm

    Science.gov (United States)

    Milecki, Andrzej; Ortmann, Jarosław

    2017-11-01

    The paper describes electrohydraulic spool valves with stepping motors used as electromechanical transducers. A new concept of a proportional valve in which two stepping motors are working differentially is introduced. Such valve changes the fluid flow proportionally to the sum or difference of the motors' steps numbers. The valve design and principle of its operation is described. Theoretical equations and simulation models are proposed for all elements of the drive, i.e., the stepping motor units, hydraulic valve and cylinder. The main features of the valve and drive operation are described; some specific problem areas covering the nature of stepping motors and their differential work in the valve are also considered. The whole servo drive non-linear model is proposed and used further for simulation investigations. The initial simulation investigations of the drive with a new valve have shown that there is a significant overshoot in the drive step response, which is not allowed in positioning process. Therefore additional effort is spent to reduce the overshoot and in consequence reduce the settling time. A special predictive algorithm is proposed to this end. Then the proposed control method is tested and further improved in simulations. Further on, the model is implemented in reality and the whole servo drive system is tested. The investigation results presented in this paper, are showing an overshoot-free positioning process which enables high positioning accuracy.

  6. A two-step recognition of signal sequences determines the translocation efficiency of proteins.

    Science.gov (United States)

    Belin, D; Bost, S; Vassalli, J D; Strub, K

    1996-02-01

    The cytosolic and secreted, N-glycosylated, forms of plasminogen activator inhibitor-2 (PAI-2) are generated by facultative translocation. To study the molecular events that result in the bi-topological distribution of proteins, we determined in vitro the capacities of several signal sequences to bind the signal recognition particle (SRP) during targeting, and to promote vectorial transport of murine PAI-2 (mPAI-2). Interestingly, the six signal sequences we compared (mPAI-2 and three mutated derivatives thereof, ovalbumin and preprolactin) were found to have the differential activities in the two events. For example, the mPAI-2 signal sequence first binds SRP with moderate efficiency and secondly promotes the vectorial transport of only a fraction of the SRP-bound nascent chains. Our results provide evidence that the translocation efficiency of proteins can be controlled by the recognition of their signal sequences at two steps: during SRP-mediated targeting and during formation of a committed translocation complex. This second recognition may occur at several time points during the insertion/translocation step. In conclusion, signal sequences have a more complex structure than previously anticipated, allowing for multiple and independent interactions with the translocation machinery.

  7. Temporary Stabilization with External Fixator in 'Tripolar' Configuration in Two Steps Treatment of Tibial Pilon Fractures.

    Science.gov (United States)

    Daghino, Walter; Messina, Marco; Filipponi, Marco; Alessandro, Massè

    2016-01-01

    The tibial pilon fractures represent a complex therapeutic problem for the orthopedic surgeon, given the frequent complications and outcomes disabling. The recent medical literature indicates that the best strategy to reduce amount of complications in tibial pilon fractures is two-stages procedure. We describe our experience in the primary stabilization of these fractures. We treated 36 cases with temporary external fixation in a simple configuration, called "tripolar": this is an essential structure (only three screws and three rods), that is possible to perform even without the availability of X-rays and with simple anesthesia or sedation. We found a sufficient mechanical stability for the nursing post-operative, in absence of intraoperative and postoperative problems. The time between trauma and temporary stabilization ranged between 3 and 144 hours; surgical average time was 8.4 minutes. Definitive treatment was carried out with a delay of a minimum of 4 and a maximum of 15 days from the temporary stabilization, always without problems, both in case of ORIF (open reduction, internal fixation) or circular external fixation. Temporary stabilization with external fixator in 'tripolar' configuration seems to be the most effective strategy in two steps treatment of tibial pilon fractures. These preliminary encouraging results must be confirmed by further studies with more cases.

  8. Two-steps microwave-assisted treatment on acid hydrolysis of sago pith for bioethanol production

    Science.gov (United States)

    Sunarti, T. C.; Yanti, S. D.; Ruriani, E.

    2017-05-01

    Sago is a genus of palm that can be utilized to produce fermentable sugars as substrate for bioethanol. Sago pith is a heterogeneous substrate consists of starch and fiber. Acid hydrolysis by microwave heating radiation can break down starch and fibers together in a very short time, so it is considered to be very efficient process. The use of microwave energy (as power level) and variation of heating time can produce fermentable sugar with certain characteristics. This study included the preparation and analysis of sago pith flour; process of acid hydrolysis (0.3 M and 0.5 M H2SO4) using two steps microwave heating, first with power level 30% (1, 2 and 3 min) and second with power level 70% (3 min); and ethanol production. The conventional treatment (autoclaving at 121°C for 15 min) was carried for the comparison. The highest fermentable sugar (105.7 g/l) was resulted from microwave heating with power level 30% for 2 min followed by the power level 70% for 3 min. This hydrolyzate then used as substrate for bioethanol fermentation and partially neutralized (pH 3, 4, 5) by using yeast Issatchenkia orientalis, and the highest ethanol (2.8 g/l) was produced in pH 5.

  9. A Two-Step Hybrid Approach for Modeling the Nonlinear Dynamic Response of Piezoelectric Energy Harvesters

    Directory of Open Access Journals (Sweden)

    Claudio Maruccio

    2018-01-01

    Full Text Available An effective hybrid computational framework is described here in order to assess the nonlinear dynamic response of piezoelectric energy harvesting devices. The proposed strategy basically consists of two steps. First, fully coupled multiphysics finite element (FE analyses are performed to evaluate the nonlinear static response of the device. An enhanced reduced-order model is then derived, where the global dynamic response is formulated in the state-space using lumped coefficients enriched with the information derived from the FE simulations. The electromechanical response of piezoelectric beams under forced vibrations is studied by means of the proposed approach, which is also validated by comparing numerical predictions with some experimental results. Such numerical and experimental investigations have been carried out with the main aim of studying the influence of material and geometrical parameters on the global nonlinear response. The advantage of the presented approach is that the overall computational and experimental efforts are significantly reduced while preserving a satisfactory accuracy in the assessment of the global behavior.

  10. Simple Plans or Sophisticated Habits? State, Transition and Learning Interactions in the Two-Step Task

    Science.gov (United States)

    Akam, Thomas; Costa, Rui; Dayan, Peter

    2015-01-01

    The recently developed ‘two-step’ behavioural task promises to differentiate model-based from model-free reinforcement learning, while generating neurophysiologically-friendly decision datasets with parametric variation of decision variables. These desirable features have prompted its widespread adoption. Here, we analyse the interactions between a range of different strategies and the structure of transitions and outcomes in order to examine constraints on what can be learned from behavioural performance. The task involves a trade-off between the need for stochasticity, to allow strategies to be discriminated, and a need for determinism, so that it is worth subjects’ investment of effort to exploit the contingencies optimally. We show through simulation that under certain conditions model-free strategies can masquerade as being model-based. We first show that seemingly innocuous modifications to the task structure can induce correlations between action values at the start of the trial and the subsequent trial events in such a way that analysis based on comparing successive trials can lead to erroneous conclusions. We confirm the power of a suggested correction to the analysis that can alleviate this problem. We then consider model-free reinforcement learning strategies that exploit correlations between where rewards are obtained and which actions have high expected value. These generate behaviour that appears model-based under these, and also more sophisticated, analyses. Exploiting the full potential of the two-step task as a tool for behavioural neuroscience requires an understanding of these issues. PMID:26657806

  11. Two-Step Mechanism of Membrane Disruption by Aβ through Membrane Fragmentation and Pore Formation

    Science.gov (United States)

    Sciacca, Michele F.M.; Kotler, Samuel A.; Brender, Jeffrey R.; Chen, Jennifer; Lee, Dong-kuk; Ramamoorthy, Ayyalusamy

    2012-01-01

    Disruption of cell membranes by Aβ is believed to be one of the key components of Aβ toxicity. However, the mechanism by which this occurs is not fully understood. Here, we demonstrate that membrane disruption by Aβ occurs by a two-step process, with the initial formation of ion-selective pores followed by nonspecific fragmentation of the lipid membrane during amyloid fiber formation. Immediately after the addition of freshly dissolved Aβ1–40, defects form on the membrane that share many of the properties of Aβ channels originally reported from single-channel electrical recording, such as cation selectivity and the ability to be blockaded by zinc. By contrast, subsequent amyloid fiber formation on the surface of the membrane fragments the membrane in a way that is not cation selective and cannot be stopped by zinc ions. Moreover, we observed that the presence of ganglioside enhances both the initial pore formation and the fiber-dependent membrane fragmentation process. Whereas pore formation by freshly dissolved Aβ1–40 is weakly observed in the absence of gangliosides, fiber-dependent membrane fragmentation can only be observed in their presence. These results provide insights into the toxicity of Aβ and may aid in the design of specific compounds to alleviate the neurodegeneration of Alzheimer’s disease. PMID:22947931

  12. Two-step fabrication of ZnO-PVP composites with tunable visible emissions

    Science.gov (United States)

    Agulto, Verdad C.; Empizo, Melvin John F.; Kawano, Keisuke; Minami, Yuki; Yamanoi, Kohei; Sarukura, Nobuhiko; Yago, Allan Christopher C.; Sarmago, Roland V.

    2018-02-01

    We report a two-step fabrication of zinc oxide-polyvinylpyrrolidone (ZnO-PVP) composites for potential phosphor-based applications. The composites are fabricated by initially preparing ZnO microrods using hydrothermal growth method and then dip-coating the microrods into aqueous PVP solutions with varying molar concentrations. The as-prepared ZnO microrods exhibit smooth surfaces and broad visible emissions, while the ZnO-PVP composites have pitted surfaces with shifted and reduced visible emissions. These changes in the structural and optical properties, which are found to depend on the PVP concentration, are attributed to the adsorption of PVP on the microrod surface. Although the surface morphology and visible emission are modified by PVP, the composites still maintain a hexagonal wurtzite crystal structure and near-band-edge ultraviolet (UV) emission similar with the as-prepared microrods. Our results therefore suggest that the ZnO-PVP composites can be used as phosphors that offer not only properties found in both ZnO and PVP but also tunable visible emissions which can be controlled during material fabrication.

  13. From representing to modelling knowledge: Proposing a two-step training for excellence in concept mapping

    Directory of Open Access Journals (Sweden)

    Joana G. Aguiar

    2017-09-01

    Full Text Available Training users in the concept mapping technique is critical for ensuring a high-quality concept map in terms of graphical structure and content accuracy. However, assessing excellence in concept mapping through structural and content features is a complex task. This paper proposes a two-step sequential training in concept mapping. The first step requires the fulfilment of low-order cognitive objectives (remember, understand and apply to facilitate novices’ development into good Cmappers by honing their knowledge representation skills. The second step requires the fulfilment of high-order cognitive objectives (analyse, evaluate and create to grow good Cmappers into excellent ones through the development of knowledge modelling skills. Based on Bloom’s revised taxonomy and cognitive load theory, this paper presents theoretical accounts to (1 identify the criteria distinguishing good and excellent concept maps, (2 inform instructional tasks for concept map elaboration and (3 propose a prototype for training users on concept mapping combining online and face-to-face activities. The proposed training application and the institutional certification are the next steps for the mature use of concept maps for educational as well as business purposes.

  14. Reverse pattern duplication utilizing a two-step metal lift-off process via nanoimprint lithography

    International Nuclear Information System (INIS)

    Song, Sun-Sik; Kim, Eun-Uk; Jung, Hee-Soo; Kim, Ki-Seok; Jung, Gun-Young

    2009-01-01

    A two-step metal lift-off process using a selective etching recipe was demonstrated as a new technique for the reverse pattern fabrication of the features of a master stamp via a UV-based nanoimprint lithography technique. A transparent master stamp with repeated pillars (150 nm diameter at 300 nm pitch) was fabricated by using laser interference lithography and the subsequent dry-etching process. After nanoimprint lithography and the following gold (Au) lift-off process, the corresponding gold dots (20 nm height) were generated. A thin chromium layer (Cr, 5 nm) was then deposited and subjected to the aqua regia solution, which dissolved only Au dots. By using a selective wet etching recipe between gold (Au) and chromium (Cr) materials, a Cr layer with holes was reliably generated, which was used as an etching mask to transfer holes into the silicon substrate in the subsequent dry-etching process. Hole patterns with a diameter of 146 nm were inversely replicated faithfully from the master stamp with the corresponding pillars without a notable feature size distortion

  15. Time ordering of two-step processes in energetic ion-atom collisions: Basic formalism

    International Nuclear Information System (INIS)

    Stolterfoht, N.

    1993-01-01

    The semiclassical approximation is applied in second order to describe time ordering of two-step processes in energetic ion-atom collisions. Emphasis is given to the conditions for interferences between first- and second-order terms. In systems with two active electrons, time ordering gives rise to a pair of associated paths involving a second-order process and its time-inverted process. Combining these paths within the independent-particle frozen orbital model, time ordering is lost. It is shown that the loss of time ordering modifies the second-order amplitude so that its ability to interfere with the first-order amplitude is essentially reduced. Time ordering and the capability for interference is regained, as one path is blocked by means of the Pauli exclusion principle. The time-ordering formalism is prepared for papers dealing with collision experiments of single excitation [Stolterfoht et al., following paper, Phys. Rev. A 48, 2986 (1993)] and double excitation [Stolterfoht et al. (unpublished)

  16. Two-step technique for posterior optic buttonholing of intraocular lens.

    Science.gov (United States)

    Agarwal, Tushar; Jhanji, Vishal; Singh, Digvijay; Khokhar, Sudarshan

    2014-04-01

    This study aims to describe a two-step surgical technique for placement of a posterior chamber intraocular lens (IOL) in cases with crystalline lens subluxation resulting from non-progressive zonular dialysis. The first stage entails a phacoemulsification with creation of a 4-mm posterior capsular opening using an automated vitrector. The second stage performed 6 weeks later includes an anterior vitrectomy and injection of a foldable three-piece IOL in the sulcus. The haptics of IOL are positioned in the sulcus while the optic is pushed behind the posterior capsular opening therefore "buttonholing" the IOL. Seven eyes of seven patients with posttraumatic zonular dialysis were operated using this technique. Follow-up of all cases revealed a well-centered IOL with good postoperative visual acuity (20/20 to 20/80). Our two-stage surgical technique precludes the insertion of capsular tension ring in cases with non-progressive zonular dialysis. The technique is recommended in the presence of less than or equal to 6 clock hours of zonular dialysis with preexisting posterior capsular tear or herniation of vitreous in the anterior chamber.

  17. Two-Step Injection Method for Collecting Digital Evidence in Digital Forensics

    Directory of Open Access Journals (Sweden)

    Nana Rachmana Syambas

    2015-01-01

    Full Text Available In digital forensic investigations, the investigators take digital evidence from computers, laptops or other electronic goods. There are many complications when a suspect or related person does not want to cooperate or has removed digital evidence. A lot of research has been done with the goal of retrieving data from flash memory or other digital storage media from which the content has been deleted. Unfortunately, such methods cannot guarantee that all data will be recovered. Most data can only be recovered partially and sometimes not perfectly, so that some or all files cannot be opened. This paper proposes the development of a new method for the retrieval of digital evidence called the Two-Step Injection method (TSI. It focuses on the prevention of the loss of digital evidence through the deletion of data by suspects or other parties. The advantage of this method is that the system works in secret and can be combined with other digital evidence applications that already exist, so that the accuracy and completeness of the resulting digital evidence can be improved. An experiment to test the effectiveness of the method was set up. The developed TSI system worked properly and had a 100% success rate.

  18. Two-step synthesis of silver selenide semiconductor with a linear magnetoresistance effect

    International Nuclear Information System (INIS)

    Yang, Fengxia; Xiong, Shuangtao; Liu, Fengxian; Han, Chong; Zhang, Duanming; Xia, Zhengcai

    2012-01-01

    A two-step synthesis method for polycrystalline β-silver selenide (β-Ag 2 Se) was developed. In the first step, nanopowder was prepared using a chemical conversion method at room temperature. In the second step, the nanopowder was compressed and then the bulk Ag 2 Se was fabricated by the solid-state sintering process. The crystalline phase and morphology were examined. The results showed that β-Ag 2 Se was fast fabricated at room temperature. The dense polycrystalline Ag-rich Ag 2 Se was synthesized successfully at 450 °C for 0.5 h under Argon flow. For the polycrystalline, the electronic properties and transverse magnetoresistance (TMR) in a pulsed magnetic field were investigated. The samples displayed n-type semiconducting behaviors and a critical temperature with a broaden temperature range of 140–150 K. Also, it presented a positive and nearly linear dependence on magnetic field H at H ≥ H c (crossover field) ranging from 2 to 20 T. Moreover, the linear dependence of TMR at strong field was non-saturating up to 35 T. Combining with the observation of morphology, it is thought that this unusual TMR effect was caused by slightly excess Ag. This new synthesis method provided a potential route to synthesize nonstoichiometric silver selenide. (paper)

  19. Assessment of PDF Micromixing Models Using DNS Data for a Two-Step Reaction

    Science.gov (United States)

    Tsai, Kuochen; Chakrabarti, Mitali; Fox, Rodney O.; Hill, James C.

    1996-11-01

    Although the probability density function (PDF) method is known to treat the chemical reaction terms exactly, its application to turbulent reacting flows have been overshadowed by the ability to model the molecular mixing terms satisfactorily. In this study, two PDF molecular mixing models, the linear-mean-square-estimation (LMSE or IEM) model and the generalized interaction-by-exchange-with-the-mean (GIEM) model, are compared with the DNS data in decaying turbulence with a two-step parallel-consecutive reaction and two segregated initial conditions: ``slabs" and ``blobs". Since the molecular mixing model is expected to have a strong effect on the mean values of chemical species under such initial conditions, the model evaluation is intended to answer the following questions: Can the PDF models predict the mean values of chemical species correctly with completely segregated initial conditions? (2) Is a single molecular mixing timescale sufficient for the PDF models to predict the mean values with different initial conditions? (3) Will the chemical reactions change the molecular mixing timescales of the reacting species enough to affect the accuracy of the model's prediction for the mean values of chemical species?

  20. Two-Step Time of Arrival Estimation for Pulse-Based Ultra-Wideband Systems

    Directory of Open Access Journals (Sweden)

    H. Vincent Poor

    2008-05-01

    Full Text Available In cooperative localization systems, wireless nodes need to exchange accurate position-related information such as time-of-arrival (TOA and angle-of-arrival (AOA, in order to obtain accurate location information. One alternative for providing accurate position-related information is to use ultra-wideband (UWB signals. The high time resolution of UWB signals presents a potential for very accurate positioning based on TOA estimation. However, it is challenging to realize very accurate positioning systems in practical scenarios, due to both complexity/cost constraints and adverse channel conditions such as multipath propagation. In this paper, a two-step TOA estimation algorithm is proposed for UWB systems in order to provide accurate TOA estimation under practical constraints. In order to speed up the estimation process, the first step estimates a coarse TOA of the received signal based on received signal energy. Then, in the second step, the arrival time of the first signal path is estimated by considering a hypothesis testing approach. The proposed scheme uses low-rate correlation outputs and is able to perform accurate TOA estimation in reasonable time intervals. The simulation results are presented to analyze the performance of the estimator.

  1. A two-step FEM-SEM approach for wave propagation analysis in cable structures

    Science.gov (United States)

    Zhang, Songhan; Shen, Ruili; Wang, Tao; De Roeck, Guido; Lombaert, Geert

    2018-02-01

    Vibration-based methods are among the most widely studied in structural health monitoring (SHM). It is well known, however, that the low-order modes, characterizing the global dynamic behaviour of structures, are relatively insensitive to local damage. Such local damage may be easier to detect by methods based on wave propagation which involve local high frequency behaviour. The present work considers the numerical analysis of wave propagation in cables. A two-step approach is proposed which allows taking into account the cable sag and the distribution of the axial forces in the wave propagation analysis. In the first step, the static deformation and internal forces are obtained by the finite element method (FEM), taking into account geometric nonlinear effects. In the second step, the results from the static analysis are used to define the initial state of the dynamic analysis which is performed by means of the spectral element method (SEM). The use of the SEM in the second step of the analysis allows for a significant reduction in computational costs as compared to a FE analysis. This methodology is first verified by means of a full FE analysis for a single stretched cable. Next, simulations are made to study the effects of damage in a single stretched cable and a cable-supported truss. The results of the simulations show how damage significantly affects the high frequency response, confirming the potential of wave propagation based methods for SHM.

  2. Double ionization of atoms by ion impact: two-step models

    Energy Technology Data Exchange (ETDEWEB)

    Fiori, Marcelo [Departamento de Fisica, Universidad Nacional de Salta, Salta (Argentina); Rocha, A B [Instituto de Quimica, Departamento de FIsico-Quimica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, 21949-900, RJ (Brazil); Bielschowsky, C E [Instituto de Quimica, Departamento de FIsico-Quimica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, 21949-900, RJ (Brazil); Jalbert, Ginette [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, Rio de Janeiro, 21941-972, RJ (Brazil); Garibotti, C R [CONICET and Centro Atomico Bariloche, 8400 S. C. Bariloche, RIo Negro (Argentina)

    2006-04-14

    Total cross sections for the double ionization of He and Li atoms by the impact of H{sup +}, He{sup 2+} and Li{sup 3+} are calculated at intermediate and high energies within two-step models. The double ionization of He by the impact of other bare projectiles at a fixed energy is obtained as well. Single ionization probabilities are calculated within the continuum distorted wave -eikonal-initial-state (CDW-EIS) approximation. The required atomic bound and continuum wave functions are evaluated by numerically solving the atomic wave equation with an optimized potential model (OPM). Correlation between events is introduced by considering ion relaxation. The final state electronic correlation is considered by means of the so-called Gamow factor. We compare the transition probabilities resulting from our approach with those resulting from the use of a Rootham-Hartree-Fock initial state and a Coulomb continuum state with an effective charge. We find that the use of OPM waves gives a better agreement with the experimental results than with Coulomb waves.

  3. Theory of two-step two-proton decays of nuclei

    International Nuclear Information System (INIS)

    Kadmensky, S. G.; Ivankov, Yu. V.

    2014-01-01

    A general theory of many-body diagonal and nondiagonal one-proton decays of spherical and deformed nuclei is developed on the basis of an approach not employing R-matrix theory in describing deep-subbarrier alpha and one-proton decays of nuclei but relying on integral formulas for the widths with respect to these decays. With the aid of this theory and by means of a diagram technique, a formalism is developed for describing two-step two-proton decays of a (Z, A) parent nucleus, which proceed as two successive time-separated one-proton decays of the parent and intermediate [(Z − 1, A − 1)] nuclei, these decays being related by the Green’s function for the intermediate nucleus, G(Z − 1, A − 1). It is shown that, upon taking into account, in this Green’s function, intermediate-nucleus states that are on- and off-shell states for the decaying system, there arise, respectively, sequential and virtual two-proton decays of parent nuclei. Expressions for the widths with respect to sequential and virtual two-proton decays from the ground and excited states of spherical and deformed nuclei and for the angular and energy distributions of emitted protons are obtained

  4. Seismic data two-step recovery approach combining sparsity-promoting and hyperbolic Radon transform methods

    International Nuclear Information System (INIS)

    Wang, Hanchuang; Chen, Shengchang; Ren, Haoran; Liang, Donghui; Zhou, Huamin; She, Deping

    2015-01-01

    In current research of seismic data recovery problems, the sparsity-promoting method usually produces an insufficient recovery result at the locations of null traces. The HRT (hyperbolic Radon transform) method can be applied to problems of seismic data recovery with approximately hyperbolic events. Influenced by deviations of hyperbolic characteristics between real and ideal travel-time curves, some spurious events are usually introduced and the recovery effect of intermediate and far-offset traces is worse than that of near-offset traces. Sparsity-promoting recovery is primarily dependent on the sparsity of seismic data in the sparse transform domain (i.e. on the local waveform characteristics), whereas HRT recovery is severely affected by the global characteristics of the seismic events. Inspired by the above conclusion, a two-step recovery approach combining sparsity-promoting and time-invariant HRT methods is proposed, which is based on both local and global characteristics of the seismic data. Two implementation strategies are presented in detail, and the selection criteria of the relevant strategies is also discussed. Numerical examples of synthetic and real data verify that the new approach can achieve a better recovery effect by simultaneously overcoming the shortcomings of sparsity-promoting recovery and HRT recovery. (paper)

  5. Biodiesel production from microalgae Spirulina maxima by two step process: Optimization of process variable

    Directory of Open Access Journals (Sweden)

    M.A. Rahman

    2017-04-01

    Full Text Available Biodiesel from green energy source is gaining tremendous attention for ecofriendly and economically aspect. In this investigation, a two-step process was developed for the production of biodiesel from microalgae Spirulina maxima and determined best operating conditions for the steps. In the first stage, acid esterification was conducted to lessen acid value (AV from 10.66 to 0.51 mgKOH/g of the feedstock and optimal conditions for maximum esterified oil yielding were found at molar ratio 12:1, temperature 60°C, 1% (wt% H2SO4, and mixing intensity 400 rpm for a reaction time of 90 min. The second stage alkali transesterification was carried out for maximum biodiesel yielding (86.1% and optimal conditions were found at molar ratio 9:1, temperature 65°C, mixing intensity 600 rpm, catalyst concentration 0.75% (wt% KOH for a reaction time of 20 min. Biodiesel were analyzed according to ASTM standards and results were within standards limit. Results will helpful to produce third generation algal biodiesel from microalgae Spirulina maxima in an efficient manner.

  6. Two step esterification-transesterification process of wet greasy sewage sludge for biodiesel production.

    Science.gov (United States)

    Urrutia, C; Sangaletti-Gerhard, N; Cea, M; Suazo, A; Aliberti, A; Navia, R

    2016-01-01

    Sewage sludge generated in municipal wastewater treatment plants was used as a feedstock for biodiesel production via esterification/transesterification in a two-step process. In the first esterification step, greasy and secondary sludge were tested using acid and enzymatic catalysts. The results indicate that both catalysts performed the esterification of free fatty acids (FFA) simultaneously with the transesterification of triacylglycerols (TAG). Acid catalyst demonstrated better performance in FFA esterification compared to TAG transesterification, while enzymatic catalyst showed the ability to first hydrolyze TAG in FFA, which were esterified to methyl esters. In addition, FAME concentration using greasy sludge were higher (63.9% and 58.7%), compared with those of secondary sludge (11% and 16%), using acid and enzymatic catalysts, respectively. Therefore, only greasy sludge was used in the second step of alkaline transesterification. The alkaline transesterification of the previously esterified greasy sludge reached a maximum FAME concentration of 65.4% when using acid catalyst. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Mutation induced enhanced biosynthesis of lipase | Bapiraju ...

    African Journals Online (AJOL)

    The purpose of the present investigation is to enhance production of biomedically important enzyme lipase by subjecting the indigenous lipase producing strain Rhizopus sp. BTS-24 to improvement by natural selection and random mutagenesis (UV and N-methyl-N'-nitro-N-nitroso guanidine, NTG). The isolation of mutants ...

  8. Genetics Home Reference: lysosomal acid lipase deficiency

    Science.gov (United States)

    ... lipase deficiency develop multi-organ failure and severe malnutrition and generally do not survive past 1 year. In the later-onset form of lysosomal acid lipase deficiency , signs and symptoms vary and usually begin in mid-childhood, although they can appear anytime up to late ...

  9. Lipase in milk, curd and cheese

    NARCIS (Netherlands)

    Geurts, T.J.; Lettink, F.J.; Wouters, J.T.M.

    2003-01-01

    Presence of lipase in milk, curd, whey and cheese was studied. A small amount of the product was added to a large volume of lipase-free whole milk that had been made sensitive to lipolysis by homogenization. Increase of the acidity of the fat in the mixture, determined after incubation, was

  10. Organic Solvent Tolerant Lipases and Applications

    Directory of Open Access Journals (Sweden)

    Shivika Sharma

    2014-01-01

    Full Text Available Lipases are a group of enzymes naturally endowed with the property of performing reactions in aqueous as well as organic solvents. The esterification reactions using lipase(s could be performed in water-restricted organic media as organic solvent(s not only improve(s the solubility of substrate and reactant in reaction mixture but also permit(s the reaction in the reverse direction, and often it is easy to recover the product in organic phase in two-phase equilibrium systems. The use of organic solvent tolerant lipase in organic media has exhibited many advantages: increased activity and stability, regiospecificity and stereoselectivity, higher solubility of substrate, ease of products recovery, and ability to shift the reaction equilibrium toward synthetic direction. Therefore the search for organic solvent tolerant enzymes has been an extensive area of research. A variety of fatty acid esters are now being produced commercially using immobilized lipase in nonaqueous solvents. This review describes the organic tolerance and industrial application of lipases. The main emphasis is to study the nature of organic solvent tolerant lipases. Also, the potential industrial applications that make lipases the biocatalysts of choice for the present and future have been presented.

  11. Cyclic deformation behaviour of quenched and tempered AISI 4140 at two-step tensile-compressive-loading

    Energy Technology Data Exchange (ETDEWEB)

    Schulze, V.; Lang, K.-H.; Voehringer, O.; Macherauch, E. [Karlsruhe Univ. (T.H.) (Germany). Inst. fuer Werkstoffkunde 1

    1997-08-30

    The cyclic deformation behaviour in stress-controlled two-step experiments with one or more changes between two blocks of certain lengths and amplitudes was investigated at the technically important steel AISI 4140 (German grade 42 CrMo 4). In all two-step experiments cyclic worksoftening behaviour is found. The degree of work softening is discussed in comparison to single-step experiments. In several cases effects of static strain-ageing can be found. (orig.) 10 refs.

  12. PPARγ regulates exocrine pancreas lipase.

    Science.gov (United States)

    Danino, Hila; Naor, Ronny Peri-; Fogel, Chen; Ben-Harosh, Yael; Kadir, Rotem; Salem, Hagit; Birk, Ruth

    2016-12-01

    Pancreatic lipase (triacylglycerol lipase EC 3.1.1.3) is an essential enzyme in hydrolysis of dietary fat. Dietary fat, especially polyunsaturated fatty acids (PUFA), regulate pancreatic lipase (PNLIP); however, the molecular mechanism underlying this regulation is mostly unknown. As PUFA are known to regulate expression of proliferator-activated receptor gamma (PPARγ), and as we identified in-silico putative PPARγ binding sites within the putative PNLIP promoter sequence, we hypothesized that PUFA regulation of PNLIP might be mediated by PPARγ. We used in silico bioinformatics tools, reporter luciferase assay, PPARγ agonists and antagonists, PPARγ overexpression in exocrine pancreas AR42J and primary cells to study PPARγ regulation of PNLIP. Using in silico bioinformatics tools we mapped PPARγ binding sites (PPRE) to the putative promoter region of PNLIP. Reporter luciferase assay in AR42J rat exocrine pancreas acinar cells transfected with various constructs of the putative PNLIP promoter showed that PNLIP transcription is significantly enhanced by PPARγ dose-dependently, reaching maximal levels with multi PPRE sites. This effect was significantly augmented in the presence of PPARγ agonists and reduced by PPARγ antagonists or mutagenesis abrogating PPRE sites. Over-expression of PPARγ significantly elevated PNLIP transcript and protein levels in AR42J cells and in primary pancreas cells. Moreover, PNLIP expression was up-regulated by PPARγ agonists (pioglitazone and 15dPGJ2) and significantly down-regulated by PPARγ antagonists in non-transfected rat exocrine pancreas AR42J cell line cells. PPARγ transcriptionally regulates PNLIP gene expression. This transcript regulation resolves part of the missing link between dietary PUFA direct regulation of PNLIP. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. A Two-Step Approach for Analytical Optimal Hedging with Two Triggers

    Directory of Open Access Journals (Sweden)

    Tiesong Hu

    2016-02-01

    Full Text Available Hedging is widely used to mitigate severe water shortages in the operation of reservoirs during droughts. Rationing is usually instituted with one hedging policy, which is based only on one trigger, i.e., initial storage level or current water availability. It may perform poorly in balancing the benefits of a release during the current period versus those of carryover storage during future droughts. This study proposes a novel hedging rule to improve the efficiency of a reservoir operated to supply water, in which, based on two triggers, hedging is initiated with three different hedging sub-rules through a two-step approach. In the first step, the sub-rule is triggered based on the relationship between the initial reservoir storage level and the level of the target rule curve or the firm rule curve at the end of the current period. This step is mainly concerned with increasing the water level or not in the current period. Hedging is then triggered under the sub-rule based on current water availability in the second step, in which the trigger implicitly considers both initial and ending reservoir storage levels in the current period. Moreover, the amount of hedging is analytically derived based on the Karush–Kuhn–Tucker (KKT conditions. In addition, the hedging parameters are optimized using the improved particle swarm optimization (IPSO algorithm coupled with a rule-based simulation. A single water-supply reservoir located in Hubei Province in central China is selected as a case study. The operation results show that the proposed rule is reasonable and significantly improves the reservoir operation performance for both long-term and critical periods relative to other operation policies, such as the standard operating policy (SOP and the most commonly used hedging rules.

  14. Two step growth mechanism of Cu2ZnSnS4 thin films

    Science.gov (United States)

    Thota, Narayana; Venkata Subbaiah, Y. P.; Prathap, P.; Reddy, Y. B. K.; Hema Chandra, G.

    2014-09-01

    Cu2ZnSnS4 (CZTS) semiconductor is rapidly emerging as the best absorber layer for next generation solar photovoltaics. Its cost effectiveness, environment-friendly nature, wide presence of chemical constituents in nature and high absorption coefficient with suitable energy band gap for effective utilization of solar spectrum makes it a viable alternative. The present work summarizes the preparation of CZTS films through a two-step process consisting of co-sputtered metallic precursors on glass substrates kept at 230 °C followed by sulfurization for 2 h in the ambience of elemental sulfur vapor at different temperatures ranging from 300 to 550 °C. The X-ray diffraction (XRD) and Raman analysis make it explicit that the sulfurization temperature has significant impact on reaction mechanism resulting in various bi-metallic, mono and binary metal sulfides. The diffraction pattern noticed at 500 °C corresponding to (112), (220) and (312) planes confirms the single phase CZTS as evidenced by weak and strong Raman modes at 285, 337 and 352 cm-1. The transmittance and reflectance measurements of optimized CZTS films revealed that the films have an energy band gap of ~1.56 eV. The optimized films were characterized by scanning electron microscopy (SEM) attached with EDS to know the morphological features and elemental quantification. The single phase CZTS films have exhibited p-type conductivity with sheet resistance ~6.8×103 Ω/sq., carrier concentration ~9.1×1017 cm-3 and hole mobility ~16.6 cm2V-1 s-1.

  15. A two-step method for fast and reliable EUV mask metrology

    Science.gov (United States)

    Helfenstein, Patrick; Mochi, Iacopo; Rajendran, Rajeev; Yoshitake, Shusuke; Ekinci, Yasin

    2017-03-01

    One of the major obstacles towards the implementation of extreme ultraviolet lithography for upcoming technology nodes in semiconductor industry remains the realization of a fast and reliable detection methods patterned mask defects. We are developing a reflective EUV mask-scanning lensless imaging tool (RESCAN), installed at the Swiss Light Source synchrotron at the Paul Scherrer Institut. Our system is based on a two-step defect inspection method. In the first step, a low-resolution defect map is generated by die to die comparison of the diffraction patterns from areas with programmed defects, to those from areas that are known to be defect-free on our test sample. In a later stage, a die to database comparison will be implemented in which the measured diffraction patterns will be compared to those calculated directly from the mask layout. This Scattering Scanning Contrast Microscopy technique operates purely in the Fourier domain without the need to obtain the aerial image and, given a sufficient signal to noise ratio, defects are found in a fast and reliable way, albeit with a location accuracy limited by the spot size of the incident illumination. Having thus identified rough locations for the defects, a fine scan is carried out in the vicinity of these locations. Since our source delivers coherent illumination, we can use an iterative phase-retrieval method to reconstruct the aerial image of the scanned area with - in principle - diffraction-limited resolution without the need of an objective lens. Here, we will focus on the aerial image reconstruction technique and give a few examples to illustrate the capability of the method.

  16. Novel Two-Step Classifier for Torsades de Pointes Risk Stratification from Direct Features

    Directory of Open Access Journals (Sweden)

    Jaimit Parikh

    2017-11-01

    Full Text Available While pre-clinical Torsades de Pointes (TdP risk classifiers had initially been based on drug-induced block of hERG potassium channels, it is now well established that improved risk prediction can be achieved by considering block of non-hERG ion channels. The current multi-channel TdP classifiers can be categorized into two classes. First, the classifiers that take as input the values of drug-induced block of ion channels (direct features. Second, the classifiers that are built on features extracted from output of the drug-induced multi-channel blockage simulations in the in-silico models (derived features. The classifiers built on derived features have thus far not consistently provided increased prediction accuracies, and hence casts doubt on the value of such approaches given the cost of including biophysical detail. Here, we propose a new two-step method for TdP risk classification, referred to as Multi-Channel Blockage at Early After Depolarization (MCB@EAD. In the first step, we classified the compound that produced insufficient hERG block as non-torsadogenic. In the second step, the role of non-hERG channels to modulate TdP risk are considered by constructing classifiers based on direct or derived features at critical hERG block concentrations that generates EADs in the computational cardiac cell models. MCB@EAD provides comparable or superior TdP risk classification of the drugs from the direct features in tests against published methods. TdP risk for the drugs highly correlated to the propensity to generate EADs in the model. However, the derived features of the biophysical models did not improve the predictive capability for TdP risk assessment.

  17. Porous plasmonic nanocomposites for SERS substrates fabricated by two-step laser method

    Energy Technology Data Exchange (ETDEWEB)

    Koleva, M.E., E-mail: mihaela_ek@yahoo.com [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee blvd., Sofia 1784 (Bulgaria); International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044 (Japan); Nedyalkov, N.N.; Atanasov, P.A. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee blvd., Sofia 1784 (Bulgaria); Gerlach, J.W.; Hirsch, D.; Prager, A.; Rauschenbach, B. [Leibniz Institute of Surface Modification (IOM), Permoserstrasse 15, D-04318 Leipzig (Germany); Fukata, N.; Jevasuwan, W. [International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044 (Japan)

    2016-04-25

    This research is focused on investigation of coupled plasmonic/metal-semiconductor nanomaterials. A two-step laser-assisted method is demonstrated for formation of plasmonic Ag nanoparticles (NPs) distributed into porous metal–oxide semiconductors. The mosaic Ag-ZnO target is used for laser ablation and, subsequently, laser annealing of the deposited layer is applied. The plasmon resonance properties of the nanostructures produced are confirmed by optical transmission spectroscopy. The wurtzite structure of ZnO is formed with tilted c-axis orientation and, respectively, a mixed Raman mode appears at 580 cm{sup −1}. The oxygen pressure applied during a deposition process has impact on the morphology and thickness of the porous nanostructures, but not on the size and size distribution of AgNPs. The porous nanocomposites exhibited potential for SERS applications, most pronounced for the oxygen deficient sample, grown at lower oxygen pressure. The observed considerable SERS enhancement of R6G molecules on AgNP/ZnO can be attributed to the ZnO-to-molecule charge transfer contribution, enhanced by the additional electrons from the local surface plasmon resonance (LSPR) of AgNPs to the ZnO through the conduction band. - Highlights: • Porous AgNPs/ZnO composites are obtained by laser deposition and laser annealing. • Morphology and properties depend on growth oxygen pressure. • The emergence of mixed-symmetry Raman mode at 580 cm{sup −1} is registered. • The AgNPs/ZnO porous nanocomposites are suitable for SERS-active substrates. • The charge transfer enhanced by LSPR has a contribution to SERS effect.

  18. An Umeclidinium membrane sensor; Two-step optimization strategy for improved responses.

    Science.gov (United States)

    Yehia, Ali M; Monir, Hany H

    2017-09-01

    In the scientific context of membrane sensors and improved experimentation, we devised an experimentally designed protocol for sensor optimization. Two-step strategy was implemented for Umeclidinium bromide (UMEC) analysis which is a novel quinuclidine-based muscarinic antagonist used for maintenance treatment of symptoms accompanied with chronic obstructive pulmonary disease. In the first place, membrane components were screened for ideal ion exchanger, ionophore and plasticizer using three categorical factors at three levels in Taguchi design. Secondly, experimentally designed optimization was followed in order to tune the sensor up for finest responses. Twelve experiments were randomly carried out in a continuous factor design. Nernstian response, detection limit and selectivity were assigned as responses in these designs. The optimized membrane sensor contained tetrakis-[3,5-bis(trifluoro- methyl)phenyl] borate (0.44wt%) and calix[6]arene (0.43wt%) in 50.00% PVC plasticized with 49.13wt% 2-ni-tro-phenyl octylether. This sensor, along with an optimum concentration of inner filling solution (2×10 -4 molL -1 UMEC) and 2h of soaking time, attained the design objectives. Nernstian response approached 59.7mV/decade and detection limit decreased by about two order of magnitude (8×10 -8 mol L -1 ) through this optimization protocol. The proposed sensor was validated for UMEC determination in its linear range (3.16×10 -7 -1×10 -3 mol L -1 ) and challenged for selective discrimination of other congeners and inorganic cations. Results of INCRUSE ELLIPTA ® inhalation powder analyses obtained from the proposed sensor and manufacturer's UPLC were statistically compared. Moreover the proposed sensor was successfully used for the determination of UMEC in plasma samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. A two-step chemical scheme for kerosene-air premixed flames

    Energy Technology Data Exchange (ETDEWEB)

    Franzelli, B.; Riber, E.; Sanjose, M. [CERFACS, CFD Team, 42 Avenue G. Coriolis, 31057 Toulouse Cedex 01 (France); Poinsot, T. [IMFT-UMR 5502, allee du Professeur Camille Soula, 31400 Toulouse (France)

    2010-07-15

    A reduced two-step scheme (called 2S-KERO-BFER) for kerosene-air premixed flames is presented in the context of Large Eddy Simulation of reacting turbulent flows in industrial applications. The chemical mechanism is composed of two reactions corresponding to the fuel oxidation into CO and H{sub 2}O, and the CO - CO{sub 2} equilibrium. To ensure the validity of the scheme for rich combustion, the pre-exponential constants of the two reactions are tabulated versus the local equivalence ratio. The fuel and oxidizer exponents are chosen to guarantee the correct dependence of laminar flame speed with pressure. Due to a lack of experimental results, the detailed mechanism of Dagaut composed of 209 species and 1673 reactions, and the skeletal mechanism of Luche composed of 91 species and 991 reactions have been used to validate the reduced scheme. Computations of one-dimensional laminar flames have been performed with the 2S{sub K}ERO{sub B}FER scheme using the CANTERA and COSILAB softwares for a wide range of pressure ([1; 12] atm), fresh gas temperature ([300; 700] K), and equivalence ratio ([0.6; 2.0]). Results show that the flame speed is correctly predicted for the whole range of parameters, showing a maximum for stoichiometric flames, a decrease for rich combustion and a satisfactory pressure dependence. The burnt gas temperature and the dilution by Exhaust Gas Recirculation are also well reproduced. Moreover, the results for ignition delay time are in good agreement with the experiments. (author)

  20. Analyzing angular distributions for two-step dissociation mechanisms in velocity map imaging.

    Science.gov (United States)

    Straus, Daniel B; Butler, Lynne M; Alligood, Bridget W; Butler, Laurie J

    2013-08-15

    Increasingly, velocity map imaging is becoming the method of choice to study photoinduced molecular dissociation processes. This paper introduces an algorithm to analyze the measured net speed, P(vnet), and angular, β(vnet), distributions of the products from a two-step dissociation mechanism, where the first step but not the second is induced by absorption of linearly polarized laser light. Typically, this might be the photodissociation of a C-X bond (X = halogen or other atom) to produce an atom and a momentum-matched radical that has enough internal energy to subsequently dissociate (without the absorption of an additional photon). It is this second step, the dissociation of the unstable radicals, that one wishes to study, but the measured net velocity of the final products is the vector sum of the velocity imparted to the radical in the primary photodissociation (which is determined by taking data on the momentum-matched atomic cophotofragment) and the additional velocity vector imparted in the subsequent dissociation of the unstable radical. The algorithm allows one to determine, from the forward-convolution fitting of the net velocity distribution, the distribution of velocity vectors imparted in the second step of the mechanism. One can thus deduce the secondary velocity distribution, characterized by a speed distribution P(v1,2°) and an angular distribution I(θ2°), where θ2° is the angle between the dissociating radical's velocity vector and the additional velocity vector imparted to the product detected from the subsequent dissociation of the radical.

  1. Operando research in heterogeneous catalysis

    CERN Document Server

    Groot, Irene

    2017-01-01

    This book is devoted to the emerging field of techniques for visualizing atomic-scale properties of active catalysts under actual working conditions, i.e. high gas pressures and high temperatures. It explains how to understand these observations in terms of the surface structures and dynamics and their detailed interplay with the gas phase. This provides an important new link between fundamental surface physics and chemistry, and applied catalysis. The book explains the motivation and the necessity of operando studies, and positions these with respect to the more traditional low-pressure investigations on the one hand and the reality of industrial catalysis on the other. The last decade has witnessed a rapid development of new experimental and theoretical tools for operando studies of heterogeneous catalysis. The book has a strong emphasis on the new techniques and illustrates how the challenges introduced by the harsh, operando conditions are faced for each of these new tools. Therefore, one can also read th...

  2. Green chemistry by nano-catalysis

    KAUST Repository

    Polshettiwar, Vivek; Varma, Rajender S.

    2010-01-01

    the homogeneous catalysts. This review focuses on the use of nano-catalysis for green chemistry development including the strategy of using microwave heating with nano-catalysis in benign aqueous reaction media which offers an extraordinary synergistic effect

  3. Bacillus sp. PS35 Lipase-Immobilization on Styrene-Divinyl Benzene Resin and Application in Fatty Acid Methyl Ester Synthesis.

    Science.gov (United States)

    Palanisamy, Kanmani; Kuppamuthu, Kumaresan; Jeyaseelan, Aravind

    2015-09-01

    Lipase is an enzyme with immense application potential. Ester synthesis by lipase catalysis in organic media is an area of key industrial relevance. Enzymatic preparations with traits that cater to the needs of this function are hence being intensely researched. The objectives of the study were to immobilize the lipase from Bacillus sp. PS35 by cross-linking and adsorption onto styrene-divinyl benzene (Sty-Dvb) hydrophobic resin and to comparatively characterize the free and immobilized lipase preparations. The work also aimed to apply the immobilized lipase for catalysing the fatty acid methyl ester (FAME) synthesis from palm oil and optimize the process parameters for maximizing the yield. In this study, the purified lipase from Bacillus sp. PS35 was immobilized by adsorption onto styrene-divinyl benzene hydrophobic resin with gluteraldehyde cross-linking. The immobilized enzyme showed better pH and temperature stabilities than the free lipase. Organic solvent stability was also enhanced, with the relative activity in the presence of methanol being shifted from 53% to 81%, thereby facilitating the enzyme's application in fatty acid methyl ester synthesis. It exhibited remarkable storage stability over a 30-day period and after 20 repetitive uses. Cross-linking also reduced enzyme leakage by 49%. The immobilized lipase was then applied for biodiesel production from palm oil. Methanol and oil molar ratio of 5:1, three step methanol additions, and an incubation temperature of 50°C were established to be the ideal conditions favoring the transesterification reaction, resulting in 97% methyl ester yield. These promising results offer scope for further investigation and process scale up, permitting the enzyme's commercial application in a practically feasible and economically agreeable manner.

  4. Studies on reaction parameters influence on ethanolic production of coconut oil biodiesel using immobilized lipase as a catalyst

    International Nuclear Information System (INIS)

    Ribeiro, Livia M.O.; Santos, Bruno C. da S.; Almeida, Renata M.R.G.

    2012-01-01

    Biodiesel production by enzymatic catalysis has been the subject of much research for developing processes that can potentially compete with other types of catalysis. The objective of this paper was to study the variables that affect the transesterification of coconut oil in biodiesel production using immobilized enzymes as catalysts and ethanol. The transesterification reactions were carried out in closed glass reactors kept under agitation at 200 rpm and catalyzed by the commercial immobilized lipase Novozym 435. An experimental design with the variables: temperature (40–60 °C), enzyme concentration (3–7%) and oil:ethanol ratio (1:6–1:10) was carried out. The best result – 80.5% conversion – was achieved with the highest temperature, molar ratio and enzyme concentration. -- Highlights: ► Coconut oil was used to produce biodiesel by enzymatic catalysis. ► Variables that interfere in the ethanolic transesterification were studied. ► An experimental design studied: temperature; lipase concentration; oil:ethanol ratio. ► The best result was 80.5% of biodiesel under 60 °C, 7% enzyme and 1:10 of oil:ethanol.

  5. Positron studies in catalysis research

    International Nuclear Information System (INIS)

    1994-01-01

    During the past eight months, the authors have made progress in several areas relevant to the eventual use of positron techniques in catalysis research. They have come closer to the completion of their positron microscope, and at the same time have performed several studies in their non-microscopic positron spectrometer which should ultimately be applicable to catalysis. The current status of the efforts in each of these areas is summarized in the following sections: Construction of the positron microscope (optical element construction, data collection software, and electronic sub-assemblies); Doppler broadening spectroscopy of metal silicide; Positron lifetime spectroscopy of glassy polymers; and Positron lifetime measurements of pore-sizes in zeolites

  6. Catalysis and sustainable (green) chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Centi, Gabriele; Perathoner, Siglinda [Dipartimento di Chimica Industriale ed Ingegneria dei Materiali, University of Messina, Salita Sperone 31, 98166 Messina (Italy)

    2003-01-15

    Catalysis is a key technology to achieve the objectives of sustainable (green) chemistry. After introducing the concepts of sustainable (green) chemistry and a brief assessment of new sustainable chemical technologies, the relationship between catalysis and sustainable (green) chemistry is discussed and illustrated via an analysis of some selected and relevant examples. Emphasis is also given to the concept of catalytic technologies for scaling-down chemical processes, in order to develop sustainable production processes which reduce the impact on the environment to an acceptable level that allows self-depuration processes of the living environment.

  7. Prostate ultrasound imaging: evaluation of a two-step scoring system in the diagnosis of prostate cancer.

    Science.gov (United States)

    Gao, Yong; Liao, Xin-Hong; Ma, Yan; Lu, Lu; Wei, Li-Yan; Yan, Xue

    2017-12-01

    This study aims to investigate the feasibility and performance of a two-step scoring system of ultrasound imaging in the diagnosis of prostate cancer. 75 patients with 888 consecutive histopathologically verified lesions were included in this study. Step 1, an initial 5-point scoring system was developed based on conventional transrectal ultrasound (TRUS). Step 2, a final scoring system was evaluated according to contrast-enhanced transrectal ultrasound (CE-TRUS). Each lesion was evaluated using the two-step scoring system (step 1 + step 2) and compared with only using conventional TRUS (step 1). 888 lesions were histologically verified: 315 of them were prostate cancer from 46 patients and 573 were benign prostatic hypertrophy (BPH) from 29 patients. According to the two-step scoring system, 284 lesions were upgraded and 130 lesions were downgraded from step 1 to step 2 (this means using step 2 to assess the results by step 1). However, 96 cases were improperly upgraded after step 2 and 48 malignant lesions were still missed after step 2 as score-1. For the two-step scoring system, the sensitivity, specificity, and accuracy were 84.7%, 83.2%, and 83.7%, respectively, versus 22.8%, 96.6%, and 70.4%, respectively, for conventional TRUS. The area under the ROC curve (AUC) for lesion diagnosis was 0.799-0.952 for the two-step scoring system, versus 0.479-0.712 for conventional TRUS. The difference in the diagnostic accuracy of the two-step scoring system and conventional TRUS was statistically significant (Pstep scoring system was straightforward to use and achieved a considerably accurate diagnostic performance for prostate cancer. The application of the two-step scoring system for prostate cancer is promising.

  8. EMSL and Institute for Integrated Catalysis (IIC) Catalysis Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, Charles T.; Datye, Abhaya K.; Henkelman, Graeme A.; Lobo, Raul F.; Schneider, William F.; Spicer, Leonard D.; Tysoe, Wilfred T.; Vohs, John M.; Baer, Donald R.; Hoyt, David W.; Thevuthasan, Suntharampillai; Mueller, Karl T.; Wang, Chong M.; Washton, Nancy M.; Lyubinetsky, Igor; Teller, Raymond G.; Andersen, Amity; Govind, Niranjan; Kowalski, Karol; Kabius, Bernd C.; Wang, Hongfei; Campbell, Allison A.; Shelton, William A.; Bylaska, Eric J.; Peden, Charles HF; Wang, Yong; King, David L.; Henderson, Michael A.; Rousseau, Roger J.; Szanyi, Janos; Dohnalek, Zdenek; Mei, Donghai; Garrett, Bruce C.; Ray, Douglas; Futrell, Jean H.; Laskin, Julia; DuBois, Daniel L.; Kuprat, Laura R.; Plata, Charity

    2011-05-24

    Within the context of significantly accelerating scientific progress in research areas that address important societal problems, a workshop was held in November 2010 at EMSL to identify specific and topically important areas of research and capability needs in catalysis-related science.

  9. Hemolysis research of implantable axial flow pump for two -step heart transplantation in children

    Directory of Open Access Journals (Sweden)

    O. Yu. Dmitrieva

    2017-01-01

    Full Text Available Introduction. One of the main indicators characterizing mechanical circulatory support devices (artificial valve, implantable pumps, etc. is trauma of blood cells. Therefore, while developing new pumps, one of the key studies in vitro is to evaluate blood hemolysis. For an objective hemolysis analysis of pump it is required to create a standardized methodology of hemolysis studies. The object of the study in this paper is implantable axial pump DON for two-step heart transplantation in children.The aim of study is to develop a standardized methodology of hemolysis studies of blood pumps and to conduct research of pediatric axial pump DON.Materials and methods. To conduct hemolysis research we created a mock circulatory system consisting of a reservoir placed in water bath maintaining a constant working fluid (blood temperature, hydrodynamic resistance, connecting tubes, ports for blood sampling and pressure and flow measurement systems, and research pump. Test method is to estimate levels of free hemoglobin pHb obtained by blood samples during pump working in operating mode (for pediatric pump: blood flow 2.5 l/min, pressure difference 80 mmHg. Using the data obtained the standardized indices of hemolysis NIH and MIH are calculated based on pHb values, hematocrit, total hemoglobin, blood flow and working pump time.Results. We developed and realized a standardized methodology of hemolysis research by which we evaluated hemolysis of pediatric axial pump. The results of hemolysis tests allowed us to optimize the design of DON. Obtained values of hemolysis of the latest version of pediatric pump DON-3 have shown that they do conform to the requirements of minimum blood injury and it allows us to proceed to the next step of pediatric pump research – animal experiments.Conclusion. Developed methods and evaluation tools of hemolysis allow us to provide objective information on one of the most important indicators of developing

  10. Two-step deoxygenation at the end of the Paleoproterozoic Lomagundi Event

    Science.gov (United States)

    Ossa Ossa, Frantz; Eickmann, Benjamin; Hofmann, Axel; Planavsky, Noah J.; Asael, Dan; Pambo, Florent; Bekker, Andrey

    2018-03-01

    shallow (above storm wave base) marine environments. The presence of a shallow-water redoxcline points to a generally low-oxygen atmosphere-ocean system. Further, the negative co-variation between δ34 S and δ13 C values in sediments of the Francevillian Group and other sedimentary successions of similar age worldwide suggests that the inferred two-step deoxygenation corresponding to the end of the LE reflects global rather than local events that likely occurred between ∼2.1 and 2.05 Ga ago.

  11. Evaluation of cellulose-binding domain fused to a lipase for the lipase immobilization.

    Science.gov (United States)

    Hwang, Sangpill; Ahn, Jungoh; Lee, Sumin; Lee, Tai Gyu; Haam, Seungjoo; Lee, Kangtaek; Ahn, Ik-Sung; Jung, Joon-Ki

    2004-04-01

    A cellulose-binding domain (CBD) fragment of a cellulase gene of Trichoderma hazianum was fused to a lipase gene of Bacillus stearothermophilus L1 to make a gene cluster for CBD-BSL lipase. The specific activity of CBD-BSL lipase for oil hydrolysis increased by 33% after being immobilized on Avicel (microcrystalline cellulose), whereas those of CBD-BSL lipase and BSL lipase decreased by 16% and 54%, respectively, after being immobilized on silica gel. Although the loss of activity of an enzyme immobilized by adsorption has been reported previously, the loss of activity of the CBD-BSL lipase immobilized on Avicel was less than 3% after 12 h due to the irreversible binding of CBD to Avicel.

  12. Adipose cell differentiation: evidence for a two-step process in the polyamine-dependent Ob1754 clonal line.

    Science.gov (United States)

    Amri, E Z; Dani, C; Doglio, A; Etienne, J; Grimaldi, P; Ailhaud, G

    1986-01-01

    A subclone of preadipocyte Ob17 cells has been isolated (Ob1754 clonal line). Confluent Ob1754 cells treated with an inhibitor of spermidine and spermine synthesis, methylglyoxal bis(guanylhydrazone), were totally dependent upon putrescine addition for the expression of glycerol-3-phosphate dehydrogenase which behaved as a late marker of adipose conversion. Under these conditions, the early expression of lipoprotein lipase during growth arrest remained unchanged. Studies at the mRNA level showed that the expression of unidentified pOb24 and pGH3 mRNAs, which was parallel to that of lipoprotein lipase, is independent of polyamine addition whereas the late emergence of glycerol-3-phosphate dehydrogenase mRNA was putrescine-dependent and co-ordinated with the expression of pAL422 mRNA encoding for a myelin-P2 homologue [Bernlohr, Angus, Lane, Bolanowski & Kelly (1984) Proc. Natl. Acad. Sci. U.S.A. 81, 5468-5472]. The appearance of lipoprotein lipase preceded DNA synthesis and post-confluent mitoses which were both putrescine-dependent and which took place before the appearance of glycerol-3-phosphate dehydrogenase. Thus the adipose conversion of Ob1754 cells involves the expression of at least two separate sets of markers which are differently regulated. Images Fig. 3. Fig. 6. PMID:3800927

  13. Activity and stability of immobilized lipases in lipase-catalyzed modification of peanut oil

    OpenAIRE

    Soumanou Mohamed M.; Edorh Aleodjrodo P.; Bornscheuer Uwe T.

    2004-01-01

    Fatty acid release during lipolysis of peanut oil using microbial free and immobilized lipases in aqueous media was developed. Immobilized lipase from Rhizomucor miehei (RML) gave the best result from its ability to clive different fatty acids from peanut oil in such media. In organic solvent, interesterification of peanut oil with tricaprylin using immobilized lipases from RML, Chromobacterium viscosum (CVL) and Candida rugosa (CRL) was performed. The best substrate molar ratio of tricapryli...

  14. Cyclopalladated complexes in enantioselective catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Dunina, Valeria V; Gorunova, Olga N; Zykov, P A; Kochetkov, Konstantin A

    2011-01-31

    The results of the use of optically active palladacycles in enantioselective catalysis of [3,3]-sigmatropic rearrangements, aldol condensation, the Michael reaction and cross-coupling are analyzed. Reactions with allylic substrates or reagents and some other transformations are considered.

  15. Catalysis in Molten Ionic Media

    DEFF Research Database (Denmark)

    Boghosian, Soghomon; Fehrmann, Rasmus

    2013-01-01

    This chapter deals with catalysis in molten salts and ionic liquids, which are introduced and reviewed briefly, while an in-depth review of the oxidation catalyst used for the manufacturing of sulfuric acid and cleaning of flue gas from electrical power plants is the main topic of the chapter...

  16. Nonlinear Stability and Convergence of Two-Step Runge-Kutta Methods for Volterra Delay Integro-Differential Equations

    Directory of Open Access Journals (Sweden)

    Haiyan Yuan

    2013-01-01

    Full Text Available This paper introduces the stability and convergence of two-step Runge-Kutta methods with compound quadrature formula for solving nonlinear Volterra delay integro-differential equations. First, the definitions of (k,l-algebraically stable and asymptotically stable are introduced; then the asymptotical stability of a (k,l-algebraically stable two-step Runge-Kutta method with 0two-step Runge-Kutta method is algebraically stable and diagonally stable and its generalized stage order is p, then the method with compound quadrature formula is D-convergent of order at least min{p,ν}, where ν depends on the compound quadrature formula.

  17. Comparison of single-step and two-step purified coagulants from Moringa oleifera seed for turbidity and DOC removal.

    Science.gov (United States)

    Sánchez-Martín, J; Ghebremichael, K; Beltrán-Heredia, J

    2010-08-01

    The coagulant proteins from Moringa oleifera purified with single-step and two-step ion-exchange processes were used for the coagulation of surface water from Meuse river in The Netherlands. The performances of the two purified coagulants and the crude extract were assessed in terms of turbidity and DOC removal. The results indicated that the optimum dosage of the single-step purified coagulant was more than two times higher compared to the two-step purified coagulant in terms of turbidity removal. And the residual DOC in the two-step purified coagulant was lower than in single-step purified coagulant or crude extract. (c) 2010 Elsevier Ltd. All rights reserved.

  18. Arsenic removal by discontinuous ZVI two steps system for drinking water production at household scale.

    Science.gov (United States)

    Casentini, Barbara; Falcione, Fabiano Teo; Amalfitano, Stefano; Fazi, Stefano; Rossetti, Simona

    2016-12-01

    Different countries in Europe still suffer of elevated arsenic (As) concentration in groundwaters used for human consumption. In the case of households not connected to the distribution system, decentralized water supply systems, such as Point of Use (POU) and Point of Entry (POE), offer a direct benefit for the consumers. Field scale ex-situ treatment systems based on metallic iron (ZVI) are already available for the production of reduced volumes of drinking water in remote areas (village scale). To address drinking water needs at larger scale, we designed a pilot unit able to produce an elevated daily volume of water for human consumption. We tested the long-term As removal efficiency of a two steps ZVI treatment unit for the production of 400 L/day clean water based on the combination of ZVI corrosion process with sedimentation and retention of freshly formed Fe precipitates. The system treated 100 μg/L As(V)-contaminated oxic groundwater in a discontinuous operation mode at a flow rate of 1 L/min for 31 days. Final removal was 77-96% and the most performing step was aeration/sedimentation (A/S) tank with a 60-94% efficiency. Arsenic in the outflow slightly exceeded the drinking water limit of 10 μg/L only after 6000 L treated and Fe concentration was always below 0.2 mg/L. Under proposed operating conditions ZVI passivation readily occurred and, as a consequence, Fe production sharply decreased. Arsenic mobility attached to particulate was 13-60% after ZVI column and 37-100% after A/S tank. Uniform amorphous cluster of Fe nanoparticles (100 nm) formed during aeration drove As removal process with an adsorption capacity corresponding to 20.5 mg As /g Fe . Research studies often focus only on chemico-physical aspects disregarding the importance of biological processes that may co-occur and interfere with ZVI corrosion, As removal and safe water production. We explored the microbial transport dynamics by flow cytometry, proved as a suitable tool to

  19. A two-step patterning process increases the robustness of periodic patterning in the fly eye.

    Science.gov (United States)

    Gavish, Avishai; Barkai, Naama

    2016-06-01

    Complex periodic patterns can self-organize through dynamic interactions between diffusible activators and inhibitors. In the biological context, self-organized patterning is challenged by spatial heterogeneities ('noise') inherent to biological systems. How spatial variability impacts the periodic patterning mechanism and how it can be buffered to ensure precise patterning is not well understood. We examine the effect of spatial heterogeneity on the periodic patterning of the fruit fly eye, an organ composed of ∼800 miniature eye units (ommatidia) whose periodic arrangement along a hexagonal lattice self-organizes during early stages of fly development. The patterning follows a two-step process, with an initial formation of evenly spaced clusters of ∼10 cells followed by a subsequent refinement of each cluster into a single selected cell. Using a probabilistic approach, we calculate the rate of patterning errors resulting from spatial heterogeneities in cell size, position and biosynthetic capacity. Notably, error rates were largely independent of the desired cluster size but followed the distributions of signaling speeds. Pre-formation of large clusters therefore greatly increases the reproducibility of the overall periodic arrangement, suggesting that the two-stage patterning process functions to guard the pattern against errors caused by spatial heterogeneities. Our results emphasize the constraints imposed on self-organized patterning mechanisms by the need to buffer stochastic effects. Author summary Complex periodic patterns are common in nature and are observed in physical, chemical and biological systems. Understanding how these patterns are generated in a precise manner is a key challenge. Biological patterns are especially intriguing, as they are generated in a noisy environment; cell position and cell size, for example, are subject to stochastic variations, as are the strengths of the chemical signals mediating cell-to-cell communication. The need

  20. One step versus two step approach for gestational diabetes screening: systematic review and meta-analysis of the randomized trials.

    Science.gov (United States)

    Saccone, Gabriele; Caissutti, Claudia; Khalifeh, Adeeb; Meltzer, Sara; Scifres, Christina; Simhan, Hyagriv N; Kelekci, Sefa; Sevket, Osman; Berghella, Vincenzo

    2017-12-03

    To compare both the prevalence of gestational diabetes mellitus (GDM) as well as maternal and neonatal outcomes by either the one-step or the two-step approaches. Electronic databases were searched from their inception until June 2017. We included all randomized controlled trials (RCTs) comparing the one-step with the two-step approaches for the screening and diagnosis of GDM. The primary outcome was the incidence of GDM. Three RCTs (n = 2333 participants) were included in the meta-analysis. 910 were randomized to the one step approach (75 g, 2 hrs), and 1423 to the two step approach. No significant difference in the incidence of GDM was found comparing the one step versus the two step approaches (8.4 versus 4.3%; relative risk (RR) 1.64, 95%CI 0.77-3.48). Women screened with the one step approach had a significantly lower risk of preterm birth (PTB) (3.7 versus 7.6%; RR 0.49, 95%CI 0.27-0.88), cesarean delivery (16.3 versus 22.0%; RR 0.74, 95%CI 0.56-0.99), macrosomia (2.9 versus 6.9%; RR 0.43, 95%CI 0.22-0.82), neonatal hypoglycemia (1.7 versus 4.5%; RR 0.38, 95%CI 0.16-0.90), and admission to neonatal intensive care unit (NICU) (4.4 versus 9.0%; RR 0.49, 95%CI 0.29-0.84), compared to those randomized to screening with the two step approach. The one and the two step approaches were not associated with a significant difference in the incidence of GDM. However, the one step approach was associated with better maternal and perinatal outcomes.

  1. Comparative analysis of single-step and two-step biodiesel production using supercritical methanol on laboratory-scale

    International Nuclear Information System (INIS)

    Micic, Radoslav D.; Tomić, Milan D.; Kiss, Ferenc E.; Martinovic, Ferenc L.; Simikić, Mirko Ð.; Molnar, Tibor T.

    2016-01-01

    Highlights: • Single-step supercritical transesterification compared to the two-step process. • Two-step process: oil hydrolysis and subsequent supercritical methyl esterification. • Experiments were conducted in a laboratory-scale batch reactor. • Higher biodiesel yields in two-step process at milder reaction conditions. • Two-step process has potential to be cost-competitive with the single-step process. - Abstract: Single-step supercritical transesterification and two-step biodiesel production process consisting of oil hydrolysis and subsequent supercritical methyl esterification were studied and compared. For this purpose, comparative experiments were conducted in a laboratory-scale batch reactor and optimal reaction conditions (temperature, pressure, molar ratio and time) were determined. Results indicate that in comparison to a single-step transesterification, methyl esterification (second step of the two-step process) produces higher biodiesel yields (95 wt% vs. 91 wt%) at lower temperatures (270 °C vs. 350 °C), pressures (8 MPa vs. 12 MPa) and methanol to oil molar ratios (1:20 vs. 1:42). This can be explained by the fact that the reaction system consisting of free fatty acid (FFA) and methanol achieves supercritical condition at milder reaction conditions. Furthermore, the dissolved FFA increases the acidity of supercritical methanol and acts as an acid catalyst that increases the reaction rate. There is a direct correlation between FFA content of the product obtained in hydrolysis and biodiesel yields in methyl esterification. Therefore, the reaction parameters of hydrolysis were optimized to yield the highest FFA content at 12 MPa, 250 °C and 1:20 oil to water molar ratio. Results of direct material and energy costs comparison suggest that the process based on the two-step reaction has the potential to be cost-competitive with the process based on single-step supercritical transesterification. Higher biodiesel yields, similar or lower energy

  2. Ultralow-density SiO2 aerogels prepared by a two-step sol-gel process

    International Nuclear Information System (INIS)

    Wang Jue; Li Qing; Shen Jun; Zhou Bin; Chen Lingyan; Jiang; Weiyang

    1996-01-01

    Low density SiO 2 gels are prepared by a two-step sol-gel process from TEOS. The influence of various solution ratios on the gelation process is investigated. The comparative characterization of gels using different solvent, such as ethanol, acetone and methyl cyanide, is also given. The ultralow-density SiO 2 aerogels with density less than 10 kg/m 3 are prepared by CO 2 supercritical drying technique. The structure difference between SiO 2 aerogels prepared by conventional single-step process and the two-step process is also presented

  3. Molecular catalysis science: Perspective on unifying the fields of catalysis.

    Science.gov (United States)

    Ye, Rong; Hurlburt, Tyler J; Sabyrov, Kairat; Alayoglu, Selim; Somorjai, Gabor A

    2016-05-10

    Colloidal chemistry is used to control the size, shape, morphology, and composition of metal nanoparticles. Model catalysts as such are applied to catalytic transformations in the three types of catalysts: heterogeneous, homogeneous, and enzymatic. Real-time dynamics of oxidation state, coordination, and bonding of nanoparticle catalysts are put under the microscope using surface techniques such as sum-frequency generation vibrational spectroscopy and ambient pressure X-ray photoelectron spectroscopy under catalytically relevant conditions. It was demonstrated that catalytic behavior and trends are strongly tied to oxidation state, the coordination number and crystallographic orientation of metal sites, and bonding and orientation of surface adsorbates. It was also found that catalytic performance can be tuned by carefully designing and fabricating catalysts from the bottom up. Homogeneous and heterogeneous catalysts, and likely enzymes, behave similarly at the molecular level. Unifying the fields of catalysis is the key to achieving the goal of 100% selectivity in catalysis.

  4. New and future developments in catalysis catalysis by nanoparticles

    CERN Document Server

    Suib, Steven L

    2013-01-01

    New and Future Developments in Catalysis is a package of seven books that compile the latest ideas concerning alternate and renewable energy sources and the role that catalysis plays in converting new renewable feedstock into biofuels and biochemicals. Both homogeneous and heterogeneous catalysts and catalytic processes will be discussed in a unified and comprehensive approach. There will be extensive cross-referencing within all volumes. The use of catalysts in the nanoscale offers various advantages (increased efficiency and less byproducts), and these are discussed in this volume along with the various catalytic processes using nanoparticles. However, this is not without any risks and the safety aspects and effects on humans and the environment are still unknown. The present data as well as future needs are all part of this volume along with the economics involved. Offers in-depth coverage of all catalytic topics of current interest and outlines future challenges and research areas A clear and visual descr...

  5. Structural characterization of MAPLE deposited lipase biofilm

    Energy Technology Data Exchange (ETDEWEB)

    Aronne, Antonio [Department of Chemical Engineering, Materials and Industrial Production, Università degli Studi di Napoli Federico II, Piazzale V. Tecchio 80, 80125 Napoli (Italy); Ausanio, Giovanni; Bloisi, Francesco [CNR-SPIN and Department of Physics, Università degli Studi di Napoli Federico II, Piazzale V. Tecchio 80, 80125 Napoli (Italy); Calabria, Raffaela [Istituto Motori-CNR, via G. Marconi 8, 80125 Napoli (Italy); Califano, Valeria, E-mail: v.califano@im.cnr.it [Istituto Motori-CNR, via G. Marconi 8, 80125 Napoli (Italy); Fanelli, Esther [Department of Chemical Engineering, Materials and Industrial Production, Università degli Studi di Napoli Federico II, Piazzale V. Tecchio 80, 80125 Napoli (Italy); Massoli, Patrizio [Istituto Motori-CNR, via G. Marconi 8, 80125 Napoli (Italy); Vicari, Luciano R.M. [CNR-SPIN and Department of Physics, Università degli Studi di Napoli Federico II, Piazzale V. Tecchio 80, 80125 Napoli (Italy)

    2014-11-30

    Highlights: • Lipase from Candida Rugosa was deposited by Matrix Assisted Pulsed Laser Evaporation (MAPLE) on KBr pellets, mica and glass substrate. • The deposited film was characterized morphologically and structurally by optical microscopy, SEM and FTIR analysis. • Results of characterization underlined a phenomenon of aggregation taking place. • The aggregation phenomenon was reversible since lipase showed activity in the transesterification reaction between soybean oil and isopropyl alcohol once detached from the substrate. - Abstract: Lipases (triacylglycerol ester hydrolases) are enzymes used in several industrial applications. Enzymes immobilization can be used to address key issues limiting widespread application at industrial level. Immobilization efficiency is related to the ability to preserve the native conformation of the enzyme. MAPLE (Matrix Assisted Pulsed Laser Evaporation) technique, a laser deposition procedure for treating organic/polymeric/biomaterials, was applied for the deposition of lipase enzyme in an ice matrix, using near infrared laser radiation. Microscopy analysis showed that the deposition occurred in micrometric and submicrometric clusters with a wide size distribution. AFM imaging showed that inter-cluster regions are uniformly covered with smaller aggregates of nanometric size. Fourier transform infrared spectroscopy was used for both recognizing the deposited material and analyzing its secondary structure. Results showed that the protein underwent reversible self-association during the deposition process. Actually, preliminary tests of MAPLE deposited lipase used for soybean oil transesterification with isopropyl alcohol followed by gas chromatography–mass spectrometry gave results consistent with undamaged deposition of lipase.

  6. A simple two-step purification procedure for the iC3b binding collectin conglutinin

    DEFF Research Database (Denmark)

    Krogh-Meibom, Thomas; Ingvartsen, Klaus Lønne; Tornoe, Ida

    2010-01-01

    Bovine conglutinin is a serum protein involved in innate immunity. It binds calcium dependently to iC3b, a product of the complement component C3 deposited on cell surfaces, immune complexes or artificial surfaces after complement activation. We here present a simple and efficient two-step proced...

  7. Analysis of Approximations and Aperture Distortion for 3D Migration of Bistatic Radar Data with the Two-Step Approach

    Directory of Open Access Journals (Sweden)

    Zanzi Luigi

    2010-01-01

    Full Text Available The two-step approach is a fast algorithm for 3D migration originally introduced to process zero-offset seismic data. Its application to monostatic GPR (Ground Penetrating Radar data is straightforward. A direct extension of the algorithm for the application to bistatic radar data is possible provided that the TX-RX azimuth is constant. As for the zero-offset case, the two-step operator is exactly equivalent to the one-step 3D operator for a constant velocity medium and is an approximation of the one-step 3D operator for a medium where the velocity varies vertically. Two methods are explored for handling a heterogeneous medium; both are suitable for the application of the two-step approach, and they are compared in terms of accuracy of the final 3D operator. The aperture of the two-step operator is discussed, and a solution is proposed to optimize its shape. The analysis is of interest for any NDT application where the medium is expected to be heterogeneous, or where the antenna is not in direct contact with the medium (e.g., NDT of artworks, humanitarian demining, radar with air-launched antennas.

  8. A two-step process of nitrous oxide before carbon dioxide for humanely euthanizing piglets: on-farm trials

    Science.gov (United States)

    The current methods of euthanizing neonatal piglets are raising concerns from the public and scientists. Our experiment tests the use of a two-step euthanasia method using nitrous oxide (N2O) for six minutes and then carbon dioxide (CO2) as a more humane way to euthanize piglets compared to just usi...

  9. Study of the highly ordered TiO2 nanotubes physical properties prepared with two-step anodization

    Science.gov (United States)

    Pishkar, Negin; Ghoranneviss, Mahmood; Ghorannevis, Zohreh; Akbari, Hossein

    2018-06-01

    Highly ordered hexagonal closely packed titanium dioxide nanotubes (TiO2 NTs) were successfully grown by a two-step anodization process. The TiO2 NTs were synthesized by electrochemical anodization of titanium foils in an ethylene glycol based electrolyte solution containing 0.3 wt% NH4F and 2 vol% deionized (DI) water at constant potential (50 V) for 1 h at room temperature. Physical properties of the TiO2 NTs, which were prepared via one and two-step anodization, were investigated. Atomic Force Microscopy (AFM) analysis revealed that anodization and subsequently peeled off the TiO2 NTs caused to the periodic pattern on the Ti surface. In order To study the nanotubes morphology, Field Emission Scanning Electron Microscopy (FESEM) was used, which was revealed that the two-step anodization resulted highly ordered hexagonal TiO2 NTs. Crystal structures of the TiO2 NTs were mainly anatase, determined by X-ray diffraction analysis. Optical studies were performed by Diffuse Reflection Spectra (DRS) and Photoluminescence (PL) analysis showed that the band gap of TiO2 NTs prepared via two-step anodization was lower than the band gap of samples prepared by one-step anodization process.

  10. Improving the two-step remediation process for CCA-treated wood. Part I, Evaluating oxalic acid extraction

    Science.gov (United States)

    Carol Clausen

    2004-01-01

    In this study, three possible improvements to a remediation process for chromated-copper-arsenate (CCA) treated wood were evaluated. The process involves two steps: oxalic acid extraction of wood fiber followed by bacterial culture with Bacillus licheniformis CC01. The three potential improvements to the oxalic acid extraction step were (1) reusing oxalic acid for...

  11. High efficiency two-step evaporator in a cooling system; Hocheffiziente zweistufige Verdampfung in einer Kaelteanlage - Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Meister, R.; Haenni, E. [BMS-Energieanlagen AG, Wilderswil (Switzerland)

    2005-07-01

    A two-step evaporator was installed in parallel in an existing refrigeration plant with an operating capacity Q{sub o} of 130 kW. This ensured the possibility of a practical comparison between conventional evaporation and our high-efficiency two-step evaporator, without having to resort only to theoretical data. The result of this virtually one-on-one comparison in identical ambient conditions (which is not normally possible, as two systems cannot generally be installed in parallel) has confirmed what the advance calculations demonstrated, i.e. a 10% improvement in performance provided by the high-efficiency two-step evaporator. Thanks to the changeover from semi-floated to overflow operation (only tested in winter) it was possible, again as shown in previous calculations, to achieve an additional increase in performance of 5%. A basic objective was to use the high-efficiency two-step evaporator to provide stable performance in any operating situation - i.e. even after defrosting. This objective was achieved in both operating modes: semi-floated and overflow. Summer operation in overflow mode remains to be tested however, as the system has only been running in this mode since November 2004. (author)

  12. Velocity-space observation regions of high-resolution two-step reaction gamma-ray spectroscopy

    DEFF Research Database (Denmark)

    Salewski, Mirko; Nocente, M.; Gorini, G.

    2015-01-01

    High-resolution γ-ray spectroscopy (GRS) measurements resolve spectral shapes of Dopplerbroadened γ-rays. We calculate weight functions describing velocity-space sensitivities of any two-step reaction GRS measurements in magnetized plasmas using the resonant nuclear reaction 9Be(α, nγ)12C...

  13. Immobilization of Aspergillus niger F7-02 Lipase in Polysaccharide Hydrogel Beads of Irvingia gabonensis Matrix

    Directory of Open Access Journals (Sweden)

    Safaradeen Olateju Kareem

    2014-01-01

    Full Text Available The potential of polysaccharide Irvingia gabonensis matrix as enzyme immobilization support was investigated. Lipase of Aspergillus niger F7-02 was immobilized by entrapment using glutaraldehyde as the cross-linking agent and stabilized in ethanolic-formaldehyde solution. The pH and temperature stability and activity yield of the immobilized enzyme were determined. Such parameters as enzyme load, bead size, number of beads, and bead reusability were also optimized. Adequate gel strength to form stabilized beads was achieved at 15.52% (w/v Irvingia gabonensis powder, 15% (v/v partially purified lipase, 2.5% (v/v glutaraldehyde, and 3 : 1 (v/v ethanolic-formaldehyde solution. There was 3.93-fold purification when the crude enzyme was partially purified in two-step purification using Imarsil and activated charcoal. Optimum lipase activity 75.3 Ug−1 was achieved in 50 mL test solution containing 15 beads of 7 mm bead size. Relative activity 80% was retained at eight repeated cycles. The immobilization process gave activity yield of 59.1% with specific activity of 12.3 Umg−1 and stabilized at optimum pH 4.5 and temperature 55°C. Thus the effectiveness and cost-efficiency of I. gabonensis as a polymer matrix for lipase immobilization have been established.

  14. Catalysis in the Primordial World

    Directory of Open Access Journals (Sweden)

    Nenad Raos

    2017-11-01

    Full Text Available Catalysis provides orderly prebiotic synthesis and eventually its evolution into autocatalytic (self-reproduction systems. Research on homogeneous catalysis is concerned mostly with random peptide synthesis and the chances to produce catalytic peptide oligomers. Synthesis of ribose via formose reaction was found to be catalysed by B(OH4−, presumably released by weathering of borate minerals. Oxide and clay mineral surfaces provide catalytic sites for the synthesis of oligopeptides and oligonucleotides. Chemoautotrophic or iron-sulphur-world theory assumes that the first (pioneer organisms developed by catalytic processes on (Fe/NiS particles formed near/close hydrothermal vents. The review provides an overlay of possible catalytic reactions in prebiotic environment, discussing their selectivity (regioselectivity, stereoselectivity as well as geological availability of catalytic minerals and geochemical conditions enabling catalytic reactions on early Earth.

  15. Asymmetric cation-binding catalysis

    DEFF Research Database (Denmark)

    Oliveira, Maria Teresa; Lee, Jiwoong

    2017-01-01

    The employment of metal salts is quite limited in asymmetric catalysis, although it would provide an additional arsenal of safe and inexpensive reagents to create molecular functions with high optical purity. Cation chelation by polyethers increases the salts' solubility in conventional organic...... solvents, thus increasing their applicability in synthesis. The expansion of this concept to chiral polyethers led to the emergence of asymmetric cation-binding catalysis, where chiral counter anions are generated from metal salts, particularly using BINOL-based polyethers. Alkali metal salts, namely KF...... highly enantioselective silylation reactions in polyether-generated chiral environments, and leading to a record-high turnover in asymmetric organocatalysis. This can lead to further applications by the asymmetric use of other inorganic salts in various organic transformations....

  16. Thermodynamic approach and comparison of two-step and single step DME (dimethyl ether) syntheses with carbon dioxide utilization

    International Nuclear Information System (INIS)

    Chen, Wei-Hsin; Hsu, Chih-Liang; Wang, Xiao-Dong

    2016-01-01

    DME (Dimethyl ether) synthesis from syngas with CO_2 utilization through two-step and single step processes is analyzed thermodynamically. The influences of reaction temperature, H_2/CO molar ratio, and CO_2/CO molar ratio on CO and CO_2 conversions, DME selectivity and yield, and thermal behavior are evaluated. Particular attention is paid to the comparison of the performance of DME synthesis between the two different methods. In the two-step method, the addition of CO_2 suppresses the CO conversion during methanol synthesis. An increase in CO_2/CO ratio decreases the CO_2 conversion (negative effect), but increases the total consumption amount of CO_2 (positive effect). At a given reaction temperature with H_2/CO = 4, the maximum DME yield develops at CO_2/CO = 1. In the single step method, over 98% of CO can be converted and the DME yield can be as high as 0.52 mol (mol CO)"−"1 at CO_2/CO = 2. The comparison of the single step and two-step processes indicates that the maximum CO conversion, DME selectivity, and DME yield in the former are higher than those in the latter, whereas an opposite result in the maximum CO_2 conversion is observed. These results reveal that the single step process has lower thermodynamic limitation and is a better option for DME synthesis. From CO_2 utilization point of view, the operation with low temperature, high H_2/CO ratio, and low CO_2/CO ratio results in higher CO_2 conversion, irrespective of two-step or single step DME synthesis. - Highlights: • DME (Dimethyl ether) synthesis with CO_2 utilization is analyzed thermodynamically. • Single step and two-step DME syntheses are studied and compared with each other. • CO_2 addition suppresses CO conversion in MeOH synthesis but increases MeOH yield. • The performance of the single step DME synthesis is better than that of the two-step one. • Increase CO_2/CO ratio decreases CO_2 conversion but increases CO_2 consumption amount.

  17. Cosmic strings and baryon decay catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Gregory, R.; Perkins, W.B.; Davis, A.C.; Brandenberger, R.H. (Fermi National Accelerator Lab., Batavia, IL (USA); Cambridge Univ. (UK); Brown Univ., Providence, RI (USA). Dept. of Physics)

    1989-09-01

    Cosmic strings, like monopoles, can catalyze proton decay. For integer charged fermions, the cross section for catalysis is not amplified, unlike in the case of monopoles. We review the catalysis processes both in the free quark and skyrmion pictures and discuss the implications for baryogenesis. We present a computation of the cross section for monopole catalyzed skyrmion decay using classical physics. We also discuss some effects which can screen catalysis processes. 32 refs., 1 fig.

  18. Magnetic monopole catalysis of proton decay

    International Nuclear Information System (INIS)

    Marciano, W.J.; Salvino, D.

    1986-09-01

    Catalysis of proton decay by GUT magnetic monopoles (the Rubakov-Callan effect) is discussed. Combining a short-distance cross section calculation by Bernreuther and Craigie with the long-distance velocity dependent distortion factors of Arafune and Fukugita, catalysis rate predictions which can be compared with experiment are obtained. At present, hydrogen rich detectors such as water (H 2 O) and methane (CH 4 ) appear to be particularly well suited for observing catalysis by very slow monopoles. 17 refs., 1 fig

  19. Cosmic strings and baryon decay catalysis

    International Nuclear Information System (INIS)

    Gregory, R.; Perkins, W.B.; Davis, A.C.; Brandenberger, R.H.; Cambridge Univ.; Brown Univ., Providence, RI

    1989-09-01

    Cosmic strings, like monopoles, can catalyze proton decay. For integer charged fermions, the cross section for catalysis is not amplified, unlike in the case of monopoles. We review the catalysis processes both in the free quark and skyrmion pictures and discuss the implications for baryogenesis. We present a computation of the cross section for monopole catalyzed skyrmion decay using classical physics. We also discuss some effects which can screen catalysis processes. 32 refs., 1 fig

  20. Optimization of lipase production by Staphylococcus sp. Lp12

    African Journals Online (AJOL)

    USER

    2010-02-08

    Feb 8, 2010 ... an enormous attention because of their biotechnological applications. Lipases remain ... selective transformations. The exponential increase in .... mass) lipase production and pH at regular intervals of time 24, 48 and 72 h on ...

  1. Immobilization of Isolated Lipase From Moldy Copra (Aspergillus Oryzae

    Directory of Open Access Journals (Sweden)

    Seniwati Dali

    2011-01-01

    Full Text Available Enzyme immobilization is a recovery technique that has been studied in several years, using support as a media to help enzyme dissolutions to the reaction substrate. Immobilization method used in this study was adsorption method, using specific lipase from Aspergillus oryzae. Lipase was partially purified from the culture supernatant of Aspergillus oryzae. Enzyme was immobilized by adsorbed on silica gel. Studies on free and immobilized lipase systems for determination of optimum pH, optimum temperature, thermal stability and reusability were carried out. The results showed that free lipase had optimum pH 8,2 and optimum temperature 35 °C while the immobilized lipase had optimum 8,2 and optimum temperature 45 °C. The thermal stability of the immobilized lipase, relative to that of the free lipase, was markedly increased. The immobilized lipase can be reused for at least six times.

  2. FATTY ACID ETHYL ESTERS FROM MICROALGAE OF Scenedesmus ecornis BY ENZYMATIC AND ACID CATALYSIS

    Directory of Open Access Journals (Sweden)

    Gabryelle F. de Almeida

    Full Text Available Microalgae are an indispensable food source for the various growth stages of mollusks, crustaceans, and several fish species. Using a microalgae biomass present in the Amazonian ecosystem (Macapá-AP, we study extraction methods for fatty acid such as solvent extraction (magnetic stirring and/or Soxhlet and/or hydrolysis (acid and/or enzymatic catalysis followed by esterification and/or direct transesterification. Extraction of crude triacylglycerides by mechanical stirring at room temperature was more efficient than continuous reflux (Soxhlet. Subsequently, the lipid extract was subject to transesterification with ethanol and CAL-B as a biocatalyst, leading to production of fatty acid ethyl esters (FAEE. Additionally, FAEEs were prepared by hydrolysis of crude triacylglycerides followed by acid-mediated esterification or enzymatic catalysis (lipase. In this case, the type of catalyst did not significantly influence FAEE yields. In the lipid extract, we identified palmitic, linoleic, oleic, and stearic acids with palmitic acid being the most abundant. Our results suggest that enzymatic catalysis is a viable method for the extraction of lipids in the microalga, Scenedesmus ecornis.

  3. Monoacylglycerol Lipase Regulates Fever Response.

    Directory of Open Access Journals (Sweden)

    Manuel Sanchez-Alavez

    Full Text Available Cyclooxygenase inhibitors such as ibuprofen have been used for decades to control fever through reducing the levels of the pyrogenic lipid transmitter prostaglandin E2 (PGE2. Historically, phospholipases have been considered to be the primary generator of the arachidonic acid (AA precursor pool for generating PGE2 and other eicosanoids. However, recent studies have demonstrated that monoacyglycerol lipase (MAGL, through hydrolysis of the endocannabinoid 2-arachidonoylglycerol, provides a major source of AA for PGE2 synthesis in the mammalian brain under basal and neuroinflammatory states. We show here that either genetic or pharmacological ablation of MAGL leads to significantly reduced fever responses in both centrally or peripherally-administered lipopolysaccharide or interleukin-1β-induced fever models in mice. We also show that a cannabinoid CB1 receptor antagonist does not attenuate these anti-pyrogenic effects of MAGL inhibitors. Thus, much like traditional nonsteroidal anti-inflammatory drugs, MAGL inhibitors can control fever, but appear to do so through restricted control over prostaglandin production in the nervous system.

  4. Cooperative catalysis designing efficient catalysts for synthesis

    CERN Document Server

    Peters, René

    2015-01-01

    Written by experts in the field, this is a much-needed overview of the rapidly emerging field of cooperative catalysis. The authors focus on the design and development of novel high-performance catalysts for applications in organic synthesis (particularly asymmetric synthesis), covering a broad range of topics, from the latest progress in Lewis acid / Br?nsted base catalysis to e.g. metal-assisted organocatalysis, cooperative metal/enzyme catalysis, and cooperative catalysis in polymerization reactions and on solid surfaces. The chapters are classified according to the type of cooperating acti

  5. Solid acid catalysis from fundamentals to applications

    CERN Document Server

    Hattori, Hideshi

    2014-01-01

    IntroductionTypes of solid acid catalystsAdvantages of solid acid catalysts Historical overviews of solid acid catalystsFuture outlookSolid Acids CatalysisDefinition of acid and base -Brnsted acid and Lewis acid-Acid sites on surfacesAcid strengthRole of acid sites in catalysisBifunctional catalysisPore size effect on catalysis -shape selectivity-Characterization of Solid Acid Catalysts Indicator methodTemperature programmed desorption (TPD) of ammoniaCalorimetry of adsorption of basic moleculesInfrare

  6. Dynamic expression reveals a two-step patterning of WUS and CLV3 during axillary shoot meristem formation in Arabidopsis.

    Science.gov (United States)

    Xin, Wei; Wang, Zhicai; Liang, Yan; Wang, Yonghong; Hu, Yuxin

    2017-07-01

    Seed plants have a remarkable capability to produce axillary meristems (AM) in the leaf axils, however, the dynamic establishment of a stem cell niche in AM is largely uncharacterized. We comprehensively examined the dynamic patterning of WUSCHEL (WUS) and CLAVATA3 (CLV3), the two key marker genes defining the shoot stem cell niches, during AM formation in Arabidopsis, and we found that a two-step patterning of WUS and CLV3 occurred during AM stem cell niche establishment. Our further work on the wus and clv3 mutants implicates that such two-step patterning is likely critical for the maintenance of AM progenitor cells and the specification of AM stem cell niche. These data provide a cytological frame for how a stem cell niche is established during AM formation. Copyright © 2017 Elsevier GmbH. All rights reserved.

  7. Two-step purification of scutellarin from Erigeron breviscapus (vant.) Hand. Mazz. by high-speed counter-current chromatography.

    Science.gov (United States)

    Gao, Min; Gu, Ming; Liu, Chun-Zhao

    2006-07-11

    Scutellarin, a flavone glycoside, popularly applied for the treatment of cardiopathy, has been purified in two-step purification by high-speed counter-current chromatography (HSCCC) from Erigeron breviscapus (vant.) Hand. Mazz. (Deng-zhan-hua in Chinese), a well-known traditional Chinese medicinal plant for heart disease. Two solvent systems, n-hexane-ethyl acetate-methanol-acetic acid-water (1:6:1.5:1:4, v/v/v/v/v) and ethyl acetate-n-butanol-acetonitrile-0.1% HCl (5:2:5:10, v/v/v/v) were used for the two-step purification. The purity of the collected fraction of scutellarin was 95.6%. This study supplies a new alternative method for purification of scutellarin.

  8. Controllable two-step growth and photoluminescence of waterweed-like SnO{sub 2} nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Li-Wei, E-mail: liwei0509@gmail.com [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Huang, Meng-Wen [Department of Materials Science and Engineering, National Chung Hsing University, Taichung 402, Taiwan (China); Li, Chung-Tien [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Shih, Han C., E-mail: hcshih@mx.nthu.edu.tw [Department of Materials Science and Engineering, National Chung Hsing University, Taichung 402, Taiwan (China); Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Department of Chemical and Materials Engineering, Chinese Culture University, Taipei 111, Taiwan (China)

    2013-08-15

    Waterweed-like SnO{sub 2} nanowires (NWs) were synthesized via a two-step thermal chemical vapor deposition (TVCD) process. Nanowhiskers with enlarged surface-to-volume ratio can be grown on NWs accurately, because of the product synthesized via the two-step process. These NWs and nanowhiskers with unusual [1 0 1] and [121{sup ¯}] growth directions have very straight and uniform diameters and lengths. Photoluminescence shows that waterweed-like SnO{sub 2} NWs have three prominent emission bands at 540, 612, and 668 nm. The waterweed-like SnO{sub 2} can be applied in optoelectronic devices and potential applications to lithium-ion batteries, because of its high surface-to-volume ratio and high electric capacity properties.

  9. Two-step deposition of Al-doped ZnO on p-GaN to form ohmic contacts

    Science.gov (United States)

    Su, Xi; Zhang, Guozhen; Wang, Xiao; Chen, Chao; Wu, Hao; Liu, Chang

    2017-07-01

    Al-doped ZnO (AZO) thin films were deposited directly on p-GaN substrates by using a two-step deposition consisting of polymer assisted deposition (PAD) and atomic layer deposition (ALD) methods. Ohmic contacts of the AZO on p-GaN have been formed. The lowest sheet resistance of the two-step prepared AZO films reached to 145 Ω/sq, and the specific contact resistance reduced to 1.47 × 10-2 Ω·cm2. Transmittance of the AZO films remained above 80% in the visible region. The combination of PAD and ALD technique can be used to prepare p-type ohmic contacts for optoelectronics.

  10. Willingness-to-pay for steelhead trout fishing: Implications of two-step consumer decisions with short-run endowments

    Science.gov (United States)

    McKean, John R.; Johnson, Donn; Taylor, R. Garth

    2010-09-01

    Choice of the appropriate model of economic behavior is important for the measurement of nonmarket demand and benefits. Several travel cost demand model specifications are currently in use. Uncertainty exists over the efficacy of these approaches, and more theoretical and empirical study is warranted. Thus travel cost models with differing assumptions about labor markets and consumer behavior were applied to estimate the demand for steelhead trout sportfishing on an unimpounded reach of the Snake River near Lewiston, Idaho. We introduce a modified two-step decision model that incorporates endogenous time value using a latent index variable approach. The focus is on the importance of distinguishing between short-run and long-run consumer decision variables in a consistent manner. A modified Barnett two-step decision model was found superior to other models tested.

  11. A two-step annealing process for enhancing the ferroelectric properties of poly(vinylidene fluoride) (PVDF) devices

    KAUST Repository

    Park, Jihoon

    2015-01-01

    We report a simple two-step annealing scheme for the fabrication of stable non-volatile memory devices employing poly(vinylidene fluoride) (PVDF) polymer thin-films. The proposed two-step annealing scheme comprises the crystallization of the ferroelectric gamma-phase during the first step and enhancement of the PVDF film dense morphology during the second step. Moreover, when we extended the processing time of the second step, we obtained good hysteresis curves down to 1 Hz, the first such report for ferroelectric PVDF films. The PVDF films also exhibit a coercive field of 113 MV m-1 and a ferroelectric polarization of 5.4 μC cm-2. © The Royal Society of Chemistry 2015.

  12. Two step novel hydrogen system using additives to enhance hydrogen release from the hydrolysis of alane and activated aluminum

    Science.gov (United States)

    Zidan, Ragaiy; Teprovich, Joseph A.; Motyka, Theodore

    2015-12-01

    A system for the generation of hydrogen for use in portable power systems is set forth utilizing a two-step process that involves the thermal decomposition of AlH.sub.3 (10 wt % H.sub.2) followed by the hydrolysis of the activated aluminum (Al*) byproduct to release additional H.sub.2. Additionally, a process in which water is added directly without prior history to the AlH.sub.3:PA composite is also disclosed.

  13. Molecular Dynamics of Flexible Polar Cations in a Variable Confined Space: Toward Exceptional Two-Step Nonlinear Optical Switches.

    Science.gov (United States)

    Xu, Wei-Jian; He, Chun-Ting; Ji, Cheng-Min; Chen, Shao-Li; Huang, Rui-Kang; Lin, Rui-Biao; Xue, Wei; Luo, Jun-Hua; Zhang, Wei-Xiong; Chen, Xiao-Ming

    2016-07-01

    The changeable molecular dynamics of flexible polar cations in the variable confined space between inorganic chains brings about a new type of two-step nonlinear optical (NLO) switch with genuine "off-on-off" second harmonic generation (SHG) conversion between one NLO-active state and two NLO-inactive states. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Two-step laser ionization schemes for in-gas laser ionization and spectroscopy of radioactive isotopesa

    OpenAIRE

    Kudryavtsev, Yuri; Ferrer, Rafael; Huyse, Mark; Van den Bergh, Paul; Van Duppen, Piet; Vermeeren, L.

    2014-01-01

    The in-gas laser ionization and spectroscopy technique has been developed at the Leuven isotope separator on-line facility for the production and in-source laser spectroscopy studies of short-lived radioactive isotopes. In this article, results from a study to identify efficient optical schemes for the two-step resonance laser ionization of 18 elements are presented. © 2013 AIP Publishing LLC.

  15. Network diversity through decoration of trigonal-prismatic nodes: Two-step crystal engineering of cationic metal-organic materials

    KAUST Repository

    Schoedel, Alexander

    2011-10-05

    MOMs the word! In a two-step process, first a trigonal-prismatic Primary Molecular Building Block ([Cr3O(isonic)6]+, tp-PMBB-1) was formed and then it was connected to linear linkers or square-planar nodes to afford three novel highly charged cationic metal-organic materials (MOMs) with snx, snw, and stp topologies. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Enhanced age-strengthening by two-step progressive solution treatment in an Mg–Zn–Al–Re alloy

    International Nuclear Information System (INIS)

    Zhang, Jing; Yuan, Fuqing; Du, Yong

    2013-01-01

    Highlights: • A two-step progressive solution treatment schedule was proposed. • The treatment enhanced dissolution of ternary eutectic phases in Mg–Zn–Al alloy. • Solution temperature could break the limit of the ternary eutectic temperature. • There was no microstructural over-heating defect during the progressive heating. • The τ precipitates have a remarkable dispersion strengthening effect. - Abstract: A two-step progressive solution treatment was designed and performed on an as-extruded Mg–7Zn–3Al–0.7Er alloy. The resultant microstructure and mechanical properties were examined by means of scanning electron microscopy, X-ray diffractometer, differential scanning calorimetry and hardness testing. The results showed that the two-step progressive solution treatment could enhance the dissolution of the ternary eutectic phases in the Mg–Zn–Al system without the formation of microstructure over-heating defects. After homogenization for 50 h at 325 °C, the volume fraction of the undissolved particles in the Mg–7Zn–3Al–0.7Er alloy ingot was ∼4.1%. Two-step progressive solution treatment performed on the as-extruded alloy could further dissolve the particles. Only 1.5% undissolved particles remained after the treatment. The supersaturated degree of both the dissolved solute atoms and vacancies in the α-Mg matrix was expected to be increased, resulting in an enhanced age-strengthening, compared with normal solution and aging treatments. Moreover, the processed alloy exhibited a homogenous and stable fine grain structure. Remarkable dispersion strengthening effect of ternary τ (Mg 32 (Al,Zn) 49 ) precipitates occurred in Mg–Zn–Al alloy was also identified

  17. Improving the Elevated-Temperature Properties by Two-Step Heat Treatments in Al-Mn-Mg 3004 Alloys

    Science.gov (United States)

    Liu, K.; Ma, H.; Chen, X. Grant

    2018-05-01

    In the present work, two-step heat treatments with preheating at different temperatures (175 °C, 250 °C, and 330 °C) as the first step followed by the peak precipitation treatment (375 °C/48 h) as the second step were performed in Al-Mn-Mg 3004 alloys to study their effects on the formation of dispersoids and the evolution of the elevated-temperature strength and creep resistance. During the two-step heat treatments, the microhardness is gradually increased with increasing time to a plateau after 24 hours when first treated at 250 °C and 330 °C, while there is a minor decrease with time when first treated at 175 °C. Results show that both the yield strength (YS) and creep resistance at 300 °C reach the peak values after the two-step treatment of 250 °C/24 h + 375 °C/48 h. The formation of dispersoids is greatly related to the type and size of pre-existing Mg2Si precipitated during the preheating treatments. It was found that coarse rodlike β ' -Mg2Si strongly promotes the nucleation of dispersoids, while fine needle like β ″-Mg2Si has less influence. Under optimized two-step heat treatment and modified alloying elements, the YS at 300 °C can reach as high as 97 MPa with the minimum creep rate of 2.2 × 10-9 s-1 at 300 °C in Al-Mn-Mg 3004 alloys, enabling them as one of the most promising candidates in lightweight aluminum alloys for elevated-temperature applications.

  18. Realm of Thermoalkaline Lipases in Bioprocess Commodities.

    Science.gov (United States)

    Lajis, Ahmad Firdaus B

    2018-01-01

    For decades, microbial lipases are notably used as biocatalysts and efficiently catalyze various processes in many important industries. Biocatalysts are less corrosive to industrial equipment and due to their substrate specificity and regioselectivity they produced less harmful waste which promotes environmental sustainability. At present, thermostable and alkaline tolerant lipases have gained enormous interest as biocatalyst due to their stability and robustness under high temperature and alkaline environment operation. Several characteristics of the thermostable and alkaline tolerant lipases are discussed. Their molecular weight and resistance towards a range of temperature, pH, metal, and surfactants are compared. Their industrial applications in biodiesel, biodetergents, biodegreasing, and other types of bioconversions are also described. This review also discusses the advance of fermentation process for thermostable and alkaline tolerant lipases production focusing on the process development in microorganism selection and strain improvement, culture medium optimization via several optimization techniques (i.e., one-factor-at-a-time, surface response methodology, and artificial neural network), and other fermentation parameters (i.e., inoculums size, temperature, pH, agitation rate, dissolved oxygen tension (DOT), and aeration rate). Two common fermentation techniques for thermostable and alkaline tolerant lipases production which are solid-state and submerged fermentation methods are compared and discussed. Recent optimization approaches using evolutionary algorithms (i.e., Genetic Algorithm, Differential Evolution, and Particle Swarm Optimization) are also highlighted in this article.

  19. Realm of Thermoalkaline Lipases in Bioprocess Commodities

    Directory of Open Access Journals (Sweden)

    Ahmad Firdaus B. Lajis

    2018-01-01

    Full Text Available For decades, microbial lipases are notably used as biocatalysts and efficiently catalyze various processes in many important industries. Biocatalysts are less corrosive to industrial equipment and due to their substrate specificity and regioselectivity they produced less harmful waste which promotes environmental sustainability. At present, thermostable and alkaline tolerant lipases have gained enormous interest as biocatalyst due to their stability and robustness under high temperature and alkaline environment operation. Several characteristics of the thermostable and alkaline tolerant lipases are discussed. Their molecular weight and resistance towards a range of temperature, pH, metal, and surfactants are compared. Their industrial applications in biodiesel, biodetergents, biodegreasing, and other types of bioconversions are also described. This review also discusses the advance of fermentation process for thermostable and alkaline tolerant lipases production focusing on the process development in microorganism selection and strain improvement, culture medium optimization via several optimization techniques (i.e., one-factor-at-a-time, surface response methodology, and artificial neural network, and other fermentation parameters (i.e., inoculums size, temperature, pH, agitation rate, dissolved oxygen tension (DOT, and aeration rate. Two common fermentation techniques for thermostable and alkaline tolerant lipases production which are solid-state and submerged fermentation methods are compared and discussed. Recent optimization approaches using evolutionary algorithms (i.e., Genetic Algorithm, Differential Evolution, and Particle Swarm Optimization are also highlighted in this article.

  20. Two-step excitation structure changes of luminescence centers and strong tunable blue emission on surface of silica nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Lei, E-mail: nanoyang@qq.com; Jiang, Zhongcheng; Dong, Jiazhang; Zhang, Liuqian [Hunan University, College of Materials Science and Engineering (China); Pan, Anlian, E-mail: anlian.pan@gmail.com; Zhuang, Xiujuan [Hunan University, Key Laboratory for Micro-Nano Physics and Technology of Hunan Province (China)

    2015-10-15

    We report a scheme for investigating two-step stimulated structure change of luminescence centers. Amorphous silica nanospheres with uniform diameter of 9–15 nm have been synthesized by Stöber method. Strong hydroxyl-related infrared-absorption band is observed in infrared spectrum. The surface hydroxyl groups exert great influence on the luminescent behavior of silica. They provide stable and intermediate energy states to accommodate excitation electrons. The existence of these surface states reduces the energy barrier of photochemical reactions, creating conditions for two-step excitation process. By carefully examining excitation and emission process, the nearest excitation band is absent in both optical absorption spectrum and excitation spectrum. This later generated state confirms the generation of new luminescence centers as well as the existence of photochemical reactions. Stimulated by different energies, two-step excitation process impels different photochemical reactions, prompting generation of different lattice defects on surface area of silica. Thereby, tunable luminescence is achieved. After thermal treatment, strong gap excitation band appears with the disappearance of strong surface excitation band. Strong blue luminescence also disappears. The research is significance to precise introducing structural defects and controlling position of luminescence peaks.

  1. Bainitic transformation during the two-step quenching and partitioning process in a medium carbon steel containing silicon

    Energy Technology Data Exchange (ETDEWEB)

    Li, H.Y.; Lu, X.W. [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Wu, X.C.; Min, Y.A. [School of Materials Science and Engineering, Shanghai University, Shanghai 200240 (China); Jin, X.J., E-mail: jin@sjtu.edu.cn [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2010-09-15

    Research highlights: In this paper, SEM and TEM were used to characterize microstructure of Q and P steels with different partitioning time at 300 deg. C. The interesting phenomena were discovered and discussed: 1.Lower bainite (bainitic ferrite plus {epsilon}-carbide) rather than carbide-free bainite was observed during partitioning process. 2.The mechanical properties of Q and P steels can be tailored and adjusted through balance volume fraction of retained austenite and lower bainite during partitioning process. 3.The final amount of austenite was influenced by the transformation kinetics of lower bainite during partitioning process. According to the analysis, it can be concluded that associated with carbon partitioning from martensite to austenite, lower bainite transformation inevitably occurred. More importantly, lower bainite transformation seriously affected the mechanical properties of Q and P steels and final amount of austenite. - Abstract: A study of 40SiMnNiCr steel subjected to a two-step quenching and partitioning process (Q and P) is presented. The result suggests that strength variation of Q and P steels during the two-step Q and P process was a cumulative effect of increase of retained austenite fraction, decrease of carbon supersaturation of virgin martensite, and particularly much of lower bainite formation. A trade-off between high strength and good ductility of two-step Q and P steels can be tailored and adjusted by controlling lower bainite fraction. The final amount of austenite was influenced by the transformation kinetics of lower bainite during the partitioning process.

  2. Bainitic transformation during the two-step quenching and partitioning process in a medium carbon steel containing silicon

    International Nuclear Information System (INIS)

    Li, H.Y.; Lu, X.W.; Wu, X.C.; Min, Y.A.; Jin, X.J.

    2010-01-01

    Research highlights: In this paper, SEM and TEM were used to characterize microstructure of Q and P steels with different partitioning time at 300 deg. C. The interesting phenomena were discovered and discussed: 1.Lower bainite (bainitic ferrite plus ε-carbide) rather than carbide-free bainite was observed during partitioning process. 2.The mechanical properties of Q and P steels can be tailored and adjusted through balance volume fraction of retained austenite and lower bainite during partitioning process. 3.The final amount of austenite was influenced by the transformation kinetics of lower bainite during partitioning process. According to the analysis, it can be concluded that associated with carbon partitioning from martensite to austenite, lower bainite transformation inevitably occurred. More importantly, lower bainite transformation seriously affected the mechanical properties of Q and P steels and final amount of austenite. - Abstract: A study of 40SiMnNiCr steel subjected to a two-step quenching and partitioning process (Q and P) is presented. The result suggests that strength variation of Q and P steels during the two-step Q and P process was a cumulative effect of increase of retained austenite fraction, decrease of carbon supersaturation of virgin martensite, and particularly much of lower bainite formation. A trade-off between high strength and good ductility of two-step Q and P steels can be tailored and adjusted by controlling lower bainite fraction. The final amount of austenite was influenced by the transformation kinetics of lower bainite during the partitioning process.

  3. Two-step method for creating a gastric tube during laparoscopic-thoracoscopic Ivor-Lewis esophagectomy.

    Science.gov (United States)

    Liu, Yu; Li, Ji-Jia; Zu, Peng; Liu, Hong-Xu; Yu, Zhan-Wu; Ren, Yi

    2017-12-07

    To introduce a two-step method for creating a gastric tube during laparoscopic-thoracoscopic Ivor-Lewis esophagectomy and assess its clinical application. One hundred and twenty-two patients with middle or lower esophageal cancer who underwent laparoscopic-thoracoscopic Ivor-Lewis esophagectomy at Liaoning Cancer Hospital and Institute from March 2014 to March 2016 were included in this study, and divided into two groups based on the procedure used for creating a gastric tube. One group used a two-step method for creating a gastric tube, and the other group used the conventional method. The two groups were compared regarding the operating time, surgical complications, and number of stapler cartridges used. The mean operating time was significantly shorter in the two-step method group than in the conventional method group [238 (179-293) min vs 272 (189-347) min, P creating a gastric tube during laparoscopic-thoracoscopic Ivor-Lewis esophagectomy has the advantages of simple operation, minimal damage to the tubular stomach, and reduced use of stapler cartridges.

  4. The importance of a two-step impression procedure for complete denture fabrication: a systematic review of the literature.

    Science.gov (United States)

    Regis, R R; Alves, C C S; Rocha, S S M; Negreiros, W A; Freitas-Pontes, K M

    2016-10-01

    The literature has questioned the real need for some clinical and laboratory procedures considered essential for achieving better results for complete denture fabrication. The aim of this study was to review the current literature concerning the relevance of a two-step impression procedure to achieve better clinical results in fabricating conventional complete dentures. Through an electronic search strategy of the PubMed/MEDLINE database, randomised controlled clinical trials which compared complete denture fabrication in adults in which one or two steps of impressions occurred were identified. The selections were made by three independent reviewers. Among the 540 titles initially identified, four studies (seven published papers) reporting on 257 patients evaluating aspects such as oral health-related quality of life, patient satisfaction with dentures in use, masticatory performance and chewing ability, denture quality, direct and indirect costs were considered eligible. The quality of included studies was assessed according to the Cochrane guidelines. The clinical studies considered for this review suggest that a two-step impression procedure may not be mandatory for the success of conventional complete denture fabrication regarding a variety of clinical aspects of denture quality and patients' perceptions of the treatment. © 2016 John Wiley & Sons Ltd.

  5. Sliding wear and corrosion behaviour of alloyed austempered ductile iron subjected to novel two step austempering treatment

    Science.gov (United States)

    Sethuram, D.; Srisailam, Shravani; Rao Ponangi, Babu

    2018-04-01

    Austempered Ductile Iron(ADI) is an exciting alloy of iron which offers the design engineers the best combination high strength-to-weight ratio, low cost design flexibility, good toughness, wear resistance along with fatigue strength. The two step austempering procedure helps in simultaneously improving the tensile strength as-well as the ductility to more than that of the conventional austempering process. Extensive literature survey reveals that it’s mechanical and wear behaviour are dependent on heat treatment and alloy additions. Current work focuses on characterizing the two-step ADI samples (TSADI) developed by novel heat treatment process for resistance to corrosion and wear. The samples of Ductile Iron were austempered by the two-Step Austempering process at temperatures 300°C to 450°C in the steps of 50°C.Temperaturesare gradually increased at the rate of 14°C/Hour. In acidic medium (H2SO4), the austempered samples showed better corrosive resistance compared to conventional ductile iron. It has been observed from the wear studies that TSADI sample at 350°C is showing better wear resistance compared to ductile iron. The results are discussed in terms of fractographs, process variables and microstructural features of TSADI samples.

  6. Two-Step Optimization for Spatial Accessibility Improvement: A Case Study of Health Care Planning in Rural China

    Directory of Open Access Journals (Sweden)

    Jing Luo

    2017-01-01

    Full Text Available A recent advancement in location-allocation modeling formulates a two-step approach to a new problem of minimizing disparity of spatial accessibility. Our field work in a health care planning project in a rural county in China indicated that residents valued distance or travel time from the nearest hospital foremost and then considered quality of care including less waiting time as a secondary desirability. Based on the case study, this paper further clarifies the sequential decision-making approach, termed “two-step optimization for spatial accessibility improvement (2SO4SAI.” The first step is to find the best locations to site new facilities by emphasizing accessibility as proximity to the nearest facilities with several alternative objectives under consideration. The second step adjusts the capacities of facilities for minimal inequality in accessibility, where the measure of accessibility accounts for the match ratio of supply and demand and complex spatial interaction between them. The case study illustrates how the two-step optimization method improves both aspects of spatial accessibility for health care access in rural China.

  7. The Effect of Tallow As Lipase Inducer on Total of Aspergillus Niger, Lipolitic Activity and Lipase Yield

    Directory of Open Access Journals (Sweden)

    Manik Eirry Sawitri

    2012-02-01

    Full Text Available The objectives of this research was to determined of tallow addition with different concentration as lipase Aspergillus niger inducer to total of A. niger, lipolitic activity and lipase yield. The result showed that tallow addition as inducer in the lipase A. niger production gave no significant effect on total of A. niger (5.3 x 107 – 1.7 x 108 cfu/gram in the medium. Tallow addition gave a highly significant effect on lipolytic activity and yield of lipase A. niger. Lipolytic activity ranged between 32.0354 – 53.1197 U/mg protein, while the yield of lipase was 6.6418–7.8941 µg/ml. The conclusion of this research was the addition of tallow for 8% as the lipase inducer of A. niger on lipase production was  more effective to obtain the optimal result. Keywords : Tallow, lipase, inducer, Aspergillus niger

  8. Role of Hepatic Lipase and Endothelial Lipase in High-Density Lipoprotein-Mediated Reverse Cholesterol Transport

    NARCIS (Netherlands)

    Annema, Wijtske; Tietge, Uwe J. F.

    Reverse cholesterol transport (RCT) constitutes a key part of the atheroprotective properties of high-density lipoproteins (HDL). Hepatic lipase (HL) and endothelial lipase (EL) are negative regulators of plasma HDL cholesterol levels. Although overexpression of EL decreases overall

  9. Hydrogen Production by Homogeneous Catalysis: Alcohol Acceptorless Dehydrogenation

    DEFF Research Database (Denmark)

    Nielsen, Martin

    2015-01-01

    in hydrogen production from biomass using homogeneous catalysis. Homogeneous catalysis has the advance of generally performing transformations at much milder conditions than traditional heterogeneous catalysis, and hence it constitutes a promising tool for future applications for a sustainable energy sector...

  10. Biochemical Characterization of Lipases Obtained from Acinetobacter psychrotolerans Strains

    Directory of Open Access Journals (Sweden)

    Şule SEREN

    2017-12-01

    Full Text Available In this study, extracellular lipases obtained from Acinetobacter psychrotolerans strains (Xg1 and Xg2 were characterized. The effects of varying pH values (3.0-10.0 and various temperatures (10-90 °C on lipase activities were examined. Also the effects of different metal ions, organic solvents and detergents on lipases were studied. The extracellular crude lipases were concentrated using ultrafiltration. Zymogram analysis of these lipases was performed. Lipases exhibited maximum activity at pH 8 and 30 °C.  While lipase obtained from the Xg1 strain exhibited the highest stability in the presence of various organic solvents, including hexane, ethyl acetate, chloroform and N,N dietil formamide, lipase obtained from the Xg2 strain was sensitive in the presence of isopropanol, acetonitrile, and butan-1-ol. The lipases of the Xg1 and Xg2 strains were inhibited in the presence of Cu2+ and Zn2+. Also, the lipase of the Xg1 strain was inhibited in the presence of Fe3+. In the presence of EDTA, the lipase activities of the Xg1 and Xg2 strains were partially inhibited. In presence of SDS, they were exactly inhibited. According to the zymogram results, the molecular weights of the lipases obtained from the Acinetobacter psychrotolerans Xg1 and Xg2 strains have been found approximately 37 and 30 kDa, respectively.

  11. Dependency of water concentration on ethanolysis of trioleoylglycerol by lipases

    DEFF Research Database (Denmark)

    Piyatheerawong, W.; Iwasaki, Y; Xu, Xuebing

    2004-01-01

    tested (Rhizomucor miehei lipase, Burkholderia cepacia lipase and Thermomyces lanuginosus lipase) required larger amounts of free water (ca. 7-9 wt.%) for their best performance and exhibited no ethanolysis reaction at low free water concentrations. The CALB's anomalous behavior was also observed...

  12. A Quantitative Fluorescence-Based Lipase Assay

    Directory of Open Access Journals (Sweden)

    Giovanna Lomolino

    2012-01-01

    Full Text Available An easy and fast gel diffusion assay for detecting and monitoring lipase activity by quantification of fluorescein is described. By measuring the intensity of fluorescein, it is possible to obtain a calibration curve with a regression coefficient better than by using the radius of fluorescent haloes. Through the quantification of fluorescence intensity of fluorescein released after the hydrolysis of a fluorescent ester, fluorescein dibutyrate, used as substrate in agar plates, commercial and skimmed milk lipase activity were studied. Moreover, with this method, lipase activity can be monitored in reaction medium that contains compounds which are affected by turbidity or cause measurement interference for UV-spectrophotometer and fluorimeter. In this experiment, boiled skimmed milk was dispersed in the agar gel with fluorescein dibutyrate, and it was used as a reaction medium to mimic natural conditions. The development of such an assay has a potential for applications in industries ranging from pharmaceuticals to food production and monitoring.

  13. Fundamental concepts in heterogeneous catalysis

    CERN Document Server

    Norskov, Jens K; Abild-Pedersen, Frank; Bligaard, Thomas

    2014-01-01

    This book is based on a graduate course and suitable as a primer for any newcomer to the field, this book is a detailed introduction to the experimental and computational methods that are used to study how solid surfaces act as catalysts.   Features include:First comprehensive description of modern theory of heterogeneous catalysisBasis for understanding and designing experiments in the field   Allows reader to understand catalyst design principlesIntroduction to important elements of energy transformation technologyTest driven at Stanford University over several semesters

  14. Lipase kinetics: hydrolysis of triacetin by lipase from Candida cylindracea in a hollow-fiber membrane reactor

    NARCIS (Netherlands)

    Guit, R.P.M.; Kloosterman, M.; Meindersma, G.W.; Mayer, M.; Meijer, E.M.

    1991-01-01

    The aptitude of a hollow-fiber membrane reactor to det. lipase kinetics was investigated using the hydrolysis of triacetin catalyzed by lipase from C. cylindracea as a model system. The binding of the lipase to the membrane appears not to be very specific (surface adsorption), and probably its

  15. Lipase biocatalysis for useful biodegradable products

    Energy Technology Data Exchange (ETDEWEB)

    Linko, Y.Y.; Wang, Zhuo Lin; Uosukainen, E.; Seppaelae, J. [Helsinki Univ. of Technology, Espoo (Finland); Laemsae, M. [Raisio Group Oil Milling Industry, Raisio (Finland)

    1996-12-31

    It was shown that lipases can be used as biocatalysts in the production of useful biodegradable compounds such as 1-butyl oleate by direct esterification of butanol and oleic acid to decrease viscosity of biodiesel in winter use. By enzymic transesterification, a mixture of 2-ethyl-1-hexyl esters from rapeseed oil fatty acids can be obtained in good yields for use as a solvent, and of trimethylolpropane esters for use as a lubricant. Finally, it was demonstrated that polyesters with a mass average molar mass in excess of 75,000 g mol{sup -}1 can be obtained by esterification or transesterification by using lipase as biocatalyst. (author) (3 refs.)

  16. Lipase biocatalysis for useful biodegradable products

    Energy Technology Data Exchange (ETDEWEB)

    Linko, Y Y; Wang, Zhuo Lin; Uosukainen, E; Seppaelae, J [Helsinki Univ. of Technology, Espoo (Finland); Laemsae, M [Raisio Group Oil Milling Industry, Raisio (Finland)

    1997-12-31

    It was shown that lipases can be used as biocatalysts in the production of useful biodegradable compounds such as 1-butyl oleate by direct esterification of butanol and oleic acid to decrease viscosity of biodiesel in winter use. By enzymic transesterification, a mixture of 2-ethyl-1-hexyl esters from rapeseed oil fatty acids can be obtained in good yields for use as a solvent, and of trimethylolpropane esters for use as a lubricant. Finally, it was demonstrated that polyesters with a mass average molar mass in excess of 75,000 g mol{sup -}1 can be obtained by esterification or transesterification by using lipase as biocatalyst. (author) (3 refs.)

  17. DOE Laboratory Catalysis Research Symposium - Abstracts

    Energy Technology Data Exchange (ETDEWEB)

    Dunham, T.

    1999-02-01

    The conference consisted of two sessions with the following subtopics: (1) Heterogeneous Session: Novel Catalytic Materials; Photocatalysis; Novel Processing Conditions; Metals and Sulfides; Nuclear Magnetic Resonance; Metal Oxides and Partial Oxidation; Electrocatalysis; and Automotive Catalysis. (2) Homogeneous Catalysis: H-Transfer and Alkane Functionalization; Biocatalysis; Oxidation and Photocatalysis; and Novel Medical, Methods, and Catalyzed Reactions.

  18. Computational Design of Clusters for Catalysis

    Science.gov (United States)

    Jimenez-Izal, Elisa; Alexandrova, Anastassia N.

    2018-04-01

    When small clusters are studied in chemical physics or physical chemistry, one perhaps thinks of the fundamental aspects of cluster electronic structure, or precision spectroscopy in ultracold molecular beams. However, small clusters are also of interest in catalysis, where the cold ground state or an isolated cluster may not even be the right starting point. Instead, the big question is: What happens to cluster-based catalysts under real conditions of catalysis, such as high temperature and coverage with reagents? Myriads of metastable cluster states become accessible, the entire system is dynamic, and catalysis may be driven by rare sites present only under those conditions. Activity, selectivity, and stability are highly dependent on size, composition, shape, support, and environment. To probe and master cluster catalysis, sophisticated tools are being developed for precision synthesis, operando measurements, and multiscale modeling. This review intends to tell the messy story of clusters in catalysis.

  19. "Nanocrystal bilayer for tandem catalysis"

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Yusuke; Tsung, Chia Kuang; Huang, Wenyu; Huo, Ziyang; E.Habas, Susan E; Soejima, Tetsuro; Aliaga, Cesar E; Samorjai, Gabor A; Yang, Peidong

    2011-01-24

    Supported catalysts are widely used in industry and can be optimized by tuning the composition and interface of the metal nanoparticles and oxide supports. Rational design of metal-metal oxide interfaces in nanostructured catalysts is critical to achieve better reaction activities and selectivities. We introduce here a new class of nanocrystal tandem catalysts that have multiple metal-metal oxide interfaces for the catalysis of sequential reactions. We utilized a nanocrystal bilayer structure formed by assembling platinum and cerium oxide nanocube monolayers of less than 10 nm on a silica substrate. The two distinct metal-metal oxide interfaces, CeO2-Pt and Pt-SiO2, can be used to catalyse two distinct sequential reactions. The CeO2-Pt interface catalysed methanol decomposition to produce CO and H2, which were subsequently used for ethylene hydroformylation catalysed by the nearby Pt-SiO2 interface. Consequently, propanal was produced selectively from methanol and ethylene on the nanocrystal bilayer tandem catalyst. This new concept of nanocrystal tandem catalysis represents a powerful approach towards designing high-performance, multifunctional nanostructured catalysts

  20. Curvature bound from gravitational catalysis

    Science.gov (United States)

    Gies, Holger; Martini, Riccardo

    2018-04-01

    We determine bounds on the curvature of local patches of spacetime from the requirement of intact long-range chiral symmetry. The bounds arise from a scale-dependent analysis of gravitational catalysis and its influence on the effective potential for the chiral order parameter, as induced by fermionic fluctuations on a curved spacetime with local hyperbolic properties. The bound is expressed in terms of the local curvature scalar measured in units of a gauge-invariant coarse-graining scale. We argue that any effective field theory of quantum gravity obeying this curvature bound is safe from chiral symmetry breaking through gravitational catalysis and thus compatible with the simultaneous existence of chiral fermions in the low-energy spectrum. With increasing number of dimensions, the curvature bound in terms of the hyperbolic scale parameter becomes stronger. Applying the curvature bound to the asymptotic safety scenario for quantum gravity in four spacetime dimensions translates into bounds on the matter content of particle physics models.

  1. A Two-Step Approach for Analysis of Nonignorable Missing Outcomes in Longitudinal Regression: an Application to Upstate KIDS Study.

    Science.gov (United States)

    Liu, Danping; Yeung, Edwina H; McLain, Alexander C; Xie, Yunlong; Buck Louis, Germaine M; Sundaram, Rajeshwari

    2017-09-01

    Imperfect follow-up in longitudinal studies commonly leads to missing outcome data that can potentially bias the inference when the missingness is nonignorable; that is, the propensity of missingness depends on missing values in the data. In the Upstate KIDS Study, we seek to determine if the missingness of child development outcomes is nonignorable, and how a simple model assuming ignorable missingness would compare with more complicated models for a nonignorable mechanism. To correct for nonignorable missingness, the shared random effects model (SREM) jointly models the outcome and the missing mechanism. However, the computational complexity and lack of software packages has limited its practical applications. This paper proposes a novel two-step approach to handle nonignorable missing outcomes in generalized linear mixed models. We first analyse the missing mechanism with a generalized linear mixed model and predict values of the random effects; then, the outcome model is fitted adjusting for the predicted random effects to account for heterogeneity in the missingness propensity. Extensive simulation studies suggest that the proposed method is a reliable approximation to SREM, with a much faster computation. The nonignorability of missing data in the Upstate KIDS Study is estimated to be mild to moderate, and the analyses using the two-step approach or SREM are similar to the model assuming ignorable missingness. The two-step approach is a computationally straightforward method that can be conducted as sensitivity analyses in longitudinal studies to examine violations to the ignorable missingness assumption and the implications relative to health outcomes. © 2017 John Wiley & Sons Ltd.

  2. Using a Two-Step Method to Measure Transgender Identity in Latin America/the Caribbean, Portugal, and Spain

    Science.gov (United States)

    Reisner, Sari L.; Biello, Katie; Rosenberger, Joshua G.; Austin, S. Bryn; Haneuse, Sebastien; Perez-Brumer, Amaya; Novak, David S.; Mimiaga, Matthew J.

    2014-01-01

    Few comparative data are available internationally to examine health differences by transgender identity. A barrier to monitoring the health and well-being of transgender people is the lack of inclusion of measures to assess natal sex/gender identity status in surveys. Data were from a cross-sectional anonymous online survey of members (n > 36,000) of a sexual networking website targeting men who have sex with men in Spanish- and Portuguese-speaking countries/ territories in Latin America/the Caribbean, Portugal, and Spain. Natal sex/gender identity status was assessed using a two-step method (Step 1: assigned birth sex, Step 2: current gender identity). Male-to-female (MTF) and female-to-male (FTM) participants were compared to non-transgender males in age-adjusted regression models on socioeconomic status (SES) (education, income, sex work), masculine gender conformity, psychological health and well-being (lifetime suicidality, past-week depressive distress, positive self-worth, general self-rated health, gender related stressors), and sexual health (HIV-infection, past-year STIs, past-3 month unprotected anal or vaginal sex). The two-step method identified 190 transgender participants (0.54%; 158 MTF, 32 FTM). Of the 12 health-related variables, six showed significant differences between the three groups: SES, masculine gender conformity, lifetime suicidality, depressive distress, positive self-worth, and past-year genital herpes. A two-step approach is recommended for health surveillance efforts to assess natal sex/gender identity status. Cognitive testing to formally validate assigned birth sex and current gender identity survey items in Spanish and Portuguese is encouraged. PMID:25030120

  3. Minimizing cows' stress when calves were early weaned using the two-step method with nose flaps.

    Science.gov (United States)

    Ungerfeld, R; Quintans, G; Hötzel, M J

    2016-11-01

    Early weaning may be used in beef cattle production to improve reproduction rates in range conditions. However, weaning causes a stress response in cows, which may be especially strong in early weaning management, as the bond between the cow and the calf is still strong. We hypothesized that weaning calves in two steps, with the aid of anti-sucking devices (nose flaps) would reduce the behavioural stress response in the cows separated from their calves 2 months after parturition. We compared the behaviour frequency and weight change in cows that were weaned abruptly, by separation of the calf on day 0 of the study, or in two steps, consisting of the use of anti-sucking nose flaps for 5 days before permanent separation; a third group was not weaned to serve as control. Thirty-six crossbred multiparous Aberdeen Angus×Hereford cows and their calves (n=12/treatment) were managed in three paddocks with similar pasture availability, with four dyads from each treatment per paddock. Cows' behaviour was observed by direct visual instantaneous sampling, at 10 min intervals from days -3 to 11. Weaning the calves in two steps clearly attenuated the behavioural stress response observed in abruptly weaned cows, which included reductions in grazing and lying, and increases in pacing, walking and vocalizing. Our results corroborate those previously shown for cows nursing older calves, and indicate that step weaning can reduce the behavioural stress response of cows at weaning, even when the calf is weaned shortly after birth, when the bond between the cow and calf is still very strong.

  4. Thermomyces lanuginosus lipase-catalyzed synthesis of natural flavor esters in a continuous flow microreactor.

    Science.gov (United States)

    Gumel, Ahmad Mohammed; Annuar, M S M

    2016-06-01

    Enzymatic catalysis is considered to be among the most environmental friendly processes for the synthesis of fine chemicals. In this study, lipase from Thermomyces lanuginosus (Lecitase Ultra™) was used to catalyze the synthesis of flavor esters, i.e., methyl butanoate and methyl benzoate by esterification of the acids with methanol in a microfluidic system. Maximum reaction rates of 195 and 115 mM min -1 corresponding to catalytic efficiencies (k cat /K M ) of 0.30 and 0.24 min -1  mM -1 as well as yield conversion of 54 and 41 % were observed in methyl butanoate and methyl benzoate synthesis, respectively. Catalytic turnover (k cat ) was higher for methyl butanoate synthesis. Rate of synthesis and yield decreased with increasing flow rates. For both esters, increase in microfluidic flow rate resulted in increased advective transport over molecular diffusion and reaction rate, thus lower conversion. In microfluidic synthesis using T. lanuginosus lipase, the following reaction conditions were 40 °C, flow rate 0.1 mL min -1 , and 123 U g -1 enzyme loading found to be the optimum operating limits. The work demonstrated the application of enzyme(s) in a microreactor system for the synthesis of industrially important esters.

  5. Efficient One-Step Fusion PCR Based on Dual-Asymmetric Primers and Two-Step Annealing

    DEFF Research Database (Denmark)

    Liu, Yilan; Chen, Jinjin; Thygesen, Anders

    2018-01-01

    Gene splicing by fusion PCR is a versatile and widely used methodology, especially in synthetic biology. We here describe a rapid method for splicing two fragments by one-round fusion PCR with a dual-asymmetric primers and two-step annealing (ODT) method. During the process, the asymmetric...... intermediate fragments were generated in the early stage. Thereafter, they were hybridized in the subsequent cycles to serve as template for the target full-length product. The process parameters such as primer ratio, elongation temperature and cycle numbers were optimized. In addition, the fusion products...

  6. Reconstructing Genetic Regulatory Networks Using Two-Step Algorithms with the Differential Equation Models of Neural Networks.

    Science.gov (United States)

    Chen, Chi-Kan

    2017-07-26

    The identification of genetic regulatory networks (GRNs) provides insights into complex cellular processes. A class of recurrent neural networks (RNNs) captures the dynamics of GRN. Algorithms combining the RNN and machine learning schemes were proposed to reconstruct small-scale GRNs using gene expression time series. We present new GRN reconstruction methods with neural networks. The RNN is extended to a class of recurrent multilayer perceptrons (RMLPs) with latent nodes. Our methods contain two steps: the edge rank assignment step and the network construction step. The former assigns ranks to all possible edges by a recursive procedure based on the estimated weights of wires of RNN/RMLP (RE RNN /RE RMLP ), and the latter constructs a network consisting of top-ranked edges under which the optimized RNN simulates the gene expression time series. The particle swarm optimization (PSO) is applied to optimize the parameters of RNNs and RMLPs in a two-step algorithm. The proposed RE RNN -RNN and RE RMLP -RNN algorithms are tested on synthetic and experimental gene expression time series of small GRNs of about 10 genes. The experimental time series are from the studies of yeast cell cycle regulated genes and E. coli DNA repair genes. The unstable estimation of RNN using experimental time series having limited data points can lead to fairly arbitrary predicted GRNs. Our methods incorporate RNN and RMLP into a two-step structure learning procedure. Results show that the RE RMLP using the RMLP with a suitable number of latent nodes to reduce the parameter dimension often result in more accurate edge ranks than the RE RNN using the regularized RNN on short simulated time series. Combining by a weighted majority voting rule the networks derived by the RE RMLP -RNN using different numbers of latent nodes in step one to infer the GRN, the method performs consistently and outperforms published algorithms for GRN reconstruction on most benchmark time series. The framework of two-step

  7. Two-step photoconductivity in LiY x Lu1 - x F4:Ce,Yb crystals

    Science.gov (United States)

    Nurtdinova, L. A.; Korableva, S. L.; Leontiev, A. V.

    2016-10-01

    Photoconductivity of LiY x Lu1- x F4:Ce,Yb ( x = 0-1) crystals is measured under one- and two-step excitation. It is established that the photoconductivity is due to intra-center transitions from excited states of Ce3+ ions. The position of the ground 4 f-state of Ce3+ ion relative to the bottom of the conduction band is determined. The choice of pumping conditions to obtain the lasing on the 5 d-4 f transitions of trivalent cerium in these active media is substantiated.

  8. First results on photon strength functions of 78Se from the two-step γ Cascades measurement

    Science.gov (United States)

    Valenta, Stanislav; Bečvář, František; Krtička, Milan; Tomandl, Ivo

    2017-09-01

    Two-step gamma cascades (TSCs) following the radiative capture of thermal neutrons in 77Se were measured at the research reactor at Řež near Prague. Results on photon strength functions (PSFs) of 78Se, obtained from comparison of experimental TSC spectra with outcomes of simulations under different assumptions about level density and PSFs using the DICEBOX algorithm, are presented. The main attention is paid to possible manifestation of the pygmy resonance observed recently in this nucleus in the nuclear resonance fluorescence measurement and low-energy PSF enhancement observed in Oslo-type experiments for all A ≲ 100 nuclei.

  9. A two-step approach to estimating selectivity and fishing power of research gill nets used in Greenland waters

    DEFF Research Database (Denmark)

    Hovgård, Holger

    1996-01-01

    by normal distributions and could be related to mesh size in accordance with the principle of geometrical similarity. In the second step the selection parameters were estimated by a nonlinear least squares fit. The model also estimated the relative efficiency of the two capture processes and the fishing......Catches of Atlantic cod (Gadus morhua) from Greenland gill-net surveys were analyzed by a two-step approach. In the initial step the form of the selection curve was identified as binormal, which was caused by fish being gilled or caught by the maxillae. Both capture processes could be described...

  10. Low-temperature wafer direct bonding of silicon and quartz glass by a two-step wet chemical surface cleaning

    Science.gov (United States)

    Wang, Chenxi; Xu, Jikai; Zeng, Xiaorun; Tian, Yanhong; Wang, Chunqing; Suga, Tadatomo

    2018-02-01

    We demonstrate a facile bonding process for combining silicon and quartz glass wafers by a two-step wet chemical surface cleaning. After a post-annealing at 200 °C, strong bonding interfaces with no defects or microcracks were obtained. On the basis of the detailed surface and bonding interface characterizations, the bonding mechanism was explored and discussed. The amino groups terminated on the cleaned surfaces might contribute to the bonding strength enhancement during the annealing. This cost-effective bonding process has great potentials for silicon- and glass-based heterogeneous integrations without requiring a vacuum system.

  11. On correctness of some processing operations for two-step cascade intensities data from the (nth, 2γ) reaction

    International Nuclear Information System (INIS)

    Sukhovoj, A.M.; Khitrov, V.A.; Chol, Li

    2004-01-01

    An influence of some incorrectness of analysis on the level densities and radiative strength functions derived from the experimental γ spectra is considered. It was shown that the obtaining of reliable data from the reaction (n, 2γ) requires deriving dependence of the two-step cascade intensities on their primary transition energy. The influence of some conditions of an analysis of the experimental γ-spectra from the reaction ( 3 He, α) on the expected value of both level density and radiative strength functions was estimated. The ways to decrease these uncertainties are suggested

  12. A stereospecific carboxyl esterase from Bacillus coagulans hosting nonlipase activity within a lipase-like fold.

    Science.gov (United States)

    De Vitis, Valerio; Nakhnoukh, Cristina; Pinto, Andrea; Contente, Martina L; Barbiroli, Alberto; Milani, Mario; Bolognesi, Martino; Molinari, Francesco; Gourlay, Louise J; Romano, Diego

    2018-03-01

    Microbial carboxylesterases are important biocatalysts that selectively hydrolyze an extensive range of esters. Here, we report the biochemical and structural characterization of an atypical carboxylesterase from Bacillus coagulans (BCE), endowed with high enantioselectivity toward different 1,2-O-isopropylideneglycerol (IPG or solketal) esters. BCE efficiently catalyzes the production of enantiopure (S)-IPG, a chiral building block for the synthesis of β-blockers, glycerophospholipids, and prostaglandins; efficient hydrolysis was observed up to 65 °C. To gain insight into the mechanistic bases of such enantioselectivity, we solved the crystal structures of BCE in apo- and glycerol-bound forms at resolutions of 1.9 and 1.8 Å, respectively. In silico docking studies on the BCE structure confirmed that IPG esters with small acyl chains (≤ C6) were easily accommodated in the active site pocket, indicating that small conformational changes are necessary to accept longer substrates. Furthermore, docking studies suggested that enantioselectivity may be due to an improved stabilization of the tetrahedral reaction intermediate for the S-enantiomer. Contrary to the above functional data implying nonlipolytic functions, BCE displays a lipase-like 3D structure that hosts a "lid" domain capping the main entrance to the active site. In lipases the lid mediates catalysis through interfacial activation, a process that we did not observe for BCE. Overall, we present the functional-structural properties of an atypical carboxyl esterase that has nonlipase-like functions, yet possesses a lipase-like 3D fold. Our data provide original enzymatic information in view of BCE applications as an inexpensive, efficient biocatalyst for the production of enantiopure (S)-IPG. Coordinates and structure factors have been deposited in the Protein Data Bank (www.rcsb.org) under accession numbers 5O7G (apo-BCE) and 5OLU (glycerol-bound BCE). © 2017 Federation of European Biochemical

  13. Frozen Microemulsions for MAPLE Immobilization of Lipase

    Directory of Open Access Journals (Sweden)

    Valeria Califano

    2017-12-01

    Full Text Available Candida rugosa lipase (CRL was deposited by matrix assisted pulsed laser evaporation (MAPLE in order to immobilize the enzyme with a preserved native conformation, which ensures its catalytic functionality. For this purpose, the composition of the MAPLE target was optimized by adding the oil phase pentane to a water solution of the amino acid 3-(3,4-dihydroxyphenyl-2-methyl-l-alanine (m-DOPA, giving a target formed by a frozen water-lipase-pentane microemulsion. Fourier transform infrared (FTIR spectroscopy and atomic force microscopy (AFM were used to investigate the structure of MAPLE deposited lipase films. FTIR deconvolution of amide I band indicated a reduction of unfolding and aggregation, i.e., a better preserved lipase secondary structure in the sample deposited from the frozen microemulsion target. AFM images highlighted the absence of big aggregates on the surface of the sample. The functionality of the immobilized enzyme to promote transesterification was determined by thin layer chromatography, resulting in a modified specificity.

  14. Lipase and phospholipase activities of Hymenoptera venoms ...

    African Journals Online (AJOL)

    native gel), Polistes flavis venom has four major protein bands, one of which has lipase activity; with sodium dodecyl sulfate (SDS-PAGE), the venom had eighteen bands with molecular weights ranging from a maximum of 94 kD and a minimum of ...

  15. Biotechnological applications of halophilic lipases and thioesterases.

    Science.gov (United States)

    Schreck, Steven D; Grunden, Amy M

    2014-02-01

    Lipases and esterases are enzymes which hydrolyze ester bonds between a fatty acid moiety and an esterified conjugate, such as a glycerol or phosphate. These enzymes have a wide spectrum of use in industrial applications where their high activity, broad substrate specificity, and stability under harsh conditions have made them integral in biofuel production, textile processing, waste treatment, and as detergent additives. To date, these industrial applications have mainly leveraged enzymes from mesophilic and thermophilic organisms. However, increasingly, attention has turned to halophilic enzymes as catalysts in environments where high salt stability is desired. This review provides a brief overview of lipases and esterases and examines specific structural motifs and evolutionary adaptations of halophilic lipases. Finally, we examine the state of research involving these enzymes and provide an in-depth look at an exciting algal-based biofuel production system. This system uses a recombinant halophilic lipase to increase oil production efficiency by cleaving algal fatty acids from the acyl carrier protein, which eliminates feedback inhibition of fatty acid synthesis.

  16. Production and characterization of lipase from Bacillus ...

    African Journals Online (AJOL)

    Jane

    2011-10-10

    Oct 10, 2011 ... properties of fats at high temperature and increased ..... Effect of growth medium pH on lipase activity, protein concentration and B. stearothermophilus growth. .... inactivation after 30 min of incubation in 10 mM Cu+2 ions.

  17. Lipase and protease extraction from activated sludge

    DEFF Research Database (Denmark)

    Gessesse, Amare; Dueholm, Thomas; Petersen, Steffen B.

    2003-01-01

    of gentle and efficient enzyme extraction methods from environmental samples is very important. In this study we present a method for the extraction of lipases and proteases from activated sludge using the non-ionic detergent Triton X-100, EDTA, and cation exchange resin (CER), alone or in combination...

  18. Enantioselective properties of induced lipases from Geotrichum

    Czech Academy of Sciences Publication Activity Database

    Zarevúcka, Marie; Kejík, Z.; Šaman, David; Wimmer, Zdeněk; Demnerová, K.

    2005-01-01

    Roč. 37, - (2005), s. 481-486 ISSN 0141-0229 R&D Projects: GA MŠk(CZ) OC D30.001; GA MŠk(CZ) OC D13.10 Institutional research plan: CEZ:AV0Z40550506 Keywords : Geotrichum * lipase * enantioselectivity Subject RIV: CC - Organic Chemistry Impact factor: 1.705, year: 2005

  19. Clinical Features of Lysosomal Acid Lipase Deficiency

    NARCIS (Netherlands)

    Burton, Barbara K.; Deegan, Patrick B.; Enns, Gregory M.; Guardamagna, Ornella; Horslen, Simon; Hovingh, Gerard K.; Lobritto, Steve J.; Malinova, Vera; McLin, Valerie A.; Raiman, Julian; Di Rocco, Maja; Santra, Saikat; Sharma, Reena; Sykut-Cegielska, Jolanta; Whitley, Chester B.; Eckert, Stephen; Valayannopoulos, Vassili; Quinn, Anthony G.

    2015-01-01

    The aim of this study was to characterize key clinical manifestations of lysosomal acid lipase deficiency (LAL D) in children and adults. Investigators reviewed medical records of LAL D patients ages ≥5 years, extracted historical data, and obtained prospective laboratory and imaging data on living

  20. Microbial lipases: Production, properties and biotechnological applications

    Directory of Open Access Journals (Sweden)

    Josana Maria Messias

    2011-09-01

    Full Text Available Lipases belong to the group of hydrolases that catalyze the hydrolysis of triacylglycerol lipids to free fatty acids and glycerol. They have significant potential biotechnological applications in catalyzing organic synthesis reactions in non-aqueous solvents using simplified procedures resulting in conversions of high yields. Lipase production has conventionally been performed by submerged fermentation; however, solid-state fermentation processes have been prominent when residues are used as substrates because they serve as low-cost nutrient sources. Microbial lipases can be used as additives in foods to modify and enhance organoleptic properties, as well as in detergents to hydrolyse fats in the treatment of oily effluents, and also have value for pharmaceutical, cosmetic, agrochemical, and oil chemical industries. More recently, they are used in transesterification reactions to convert plant seed oils into biodiesel. The objective of this work was to review the published literature on the production, properties and applications of microbial lipases, and its biotechnological role in producing biodiesel.

  1. Biocatalyst including porous enzyme cluster composite immobilized by two-step crosslinking and its utilization as enzymatic biofuel cell

    Science.gov (United States)

    Chung, Yongjin; Christwardana, Marcelinus; Tannia, Daniel Chris; Kim, Ki Jae; Kwon, Yongchai

    2017-08-01

    An enzyme cluster composite (TPA/GOx) formed from glucose oxidase (GOx) and terephthalaldehyde (TPA) that is coated onto polyethyleneimine (PEI) and carbon nanotubes (CNTs) is suggested as a new catalyst ([(TPA/GOx)/PEI]/CNT). In this catalyst, TPA promotes inter-GOx links by crosslinking to form a large and porous structure, and the TPA/GOx composite is again crosslinked with PEI/CNT to increase the amount of immobilized GOx. Such a two-step crosslinking (i) increases electron transfer because of electron delocalization by π conjugation and (ii) reduces GOx denaturation because of the formation of strong chemical bonds while its porosity facilitates mass transfer. With these features, an enzymatic biofuel cell (EBC) employing the new catalyst is fabricated and induces an excellent maximum power density (1.62 ± 0.08 mW cm-2), while the catalytic activity of the [(TPA/GOx)/PEI]/CNT catalyst is outstanding. This is clear evidence that the two-step crosslinking and porous structure caused by adoption of the TPA/GOx composite affect the performance enhancement of EBC.

  2. Two-step membrane binding by the bacterial SRP receptor enable efficient and accurate Co-translational protein targeting.

    Science.gov (United States)

    Hwang Fu, Yu-Hsien; Huang, William Y C; Shen, Kuang; Groves, Jay T; Miller, Thomas; Shan, Shu-Ou

    2017-07-28

    The signal recognition particle (SRP) delivers ~30% of the proteome to the eukaryotic endoplasmic reticulum, or the bacterial plasma membrane. The precise mechanism by which the bacterial SRP receptor, FtsY, interacts with and is regulated at the target membrane remain unclear. Here, quantitative analysis of FtsY-lipid interactions at single-molecule resolution revealed a two-step mechanism in which FtsY initially contacts membrane via a Dynamic mode, followed by an SRP-induced conformational transition to a Stable mode that activates FtsY for downstream steps. Importantly, mutational analyses revealed extensive auto-inhibitory mechanisms that prevent free FtsY from engaging membrane in the Stable mode; an engineered FtsY pre-organized into the Stable mode led to indiscriminate targeting in vitro and disrupted FtsY function in vivo. Our results show that the two-step lipid-binding mechanism uncouples the membrane association of FtsY from its conformational activation, thus optimizing the balance between the efficiency and fidelity of co-translational protein targeting.

  3. A two-step acid-catalyzed process for the production of biodiesel from rice bran oil

    Energy Technology Data Exchange (ETDEWEB)

    Zullaikah, S.; Lai, Chao Chin; Vali, S.R.; Ju, Yi Hsu [National Taiwan Univ. of Science and Technology, Taipei (China). Dept. of Chemical Engineering

    2005-11-15

    A study was undertaken to examine the effect of temperature, moisture and storage time on the accumulation of free fatty acid in the rice bran. Rice bran stored at room temperature showed that most triacylglyceride was hydrolyzed and free fatty acid (FFA) content was raised up to 76% in six months. A two-step acid-catalyzed methanolysis process was employed for the efficient conversion of rice bran oil into fatty acid methyl ester (FAME). The first step was carried out at 60 {sup o}C. Depending on the initial FFA content of oil, 55-90% FAME content in the reaction product was obtained. More than 98% FFA and less than 35% of TG were reacted in 2 h. The organic phase of the first step reaction product was used as the substrate for a second acid-catalyzed methanolysis at 100 {sup o}C. By this two-step methanolysis reaction, more than 98% FAME in the product can be obtained in less than 8 h. Distillation of reaction product gave 99.8% FAME (biodiesel) with recovery of more than 96%. The residue contains enriched nutraceuticals such as {gamma}-oryzanol (16-18%), mixture of phytosterol, tocol and steryl ester (19-21%). (author)

  4. The effect of fish oil on two-step tuberculin test in hospitalized patients: A randomized controlled trial

    Directory of Open Access Journals (Sweden)

    N. Arfa

    2018-02-01

    Full Text Available Background: According to national tuberculosis control guide, two-step tuberculin skin test (TST should be done in the elderly, if the initial test is negative. However, it raises questions about the usefulness of this approach. Objective: This study aimed to explore the effects of fish oil supplements on the two-step tuberculin test in hospitalized patients. Methods: In this randomized controlled clinical trial, 128 patients randomly allocated to control group (receiving placebo, n=64 and treatment group (receiving fish oil supplements, n=64 during 2016. Fish oil supplement group was treated with 2 g daily for 4 consecutive days. The outcome was considered a change in 2 sequential TST induration sizes. Significant increase in the size of the secondary induration compared to primary was considered 6 mm or more. Findings: There was significant difference between primary and secondary indurations of two groups (higher in treatment group (P=0.04. According to the results of analysis of variance and correlation tests, two effective factors were identified: initial induration and residence location (P=0.014 and P=0.002, respectively. In both groups, no clinically significant increase in the size of induration was observed. Conclusion: It seems that the number of cases considered as infected with tuberculosis does not increase with two- rather than one-step tuberculin skin test. Also, the short-term administration of fish oil supplements does not change this result.

  5. Microstructure and superconducting properties of Bi-2223/Ag tapes fabricated in the two-step sintering process

    International Nuclear Information System (INIS)

    Lu, X.Y.; Nagata, A.; Sugawara, K.

    2008-01-01

    The microstructure and superconducting properties of Bi-2223/Ag tapes fabricated in the two-step sintering process were investigated. The tapes were then subjected to two heat treatments with an intermediate rolling. All the tapes were sintered at 835 deg. C for 24 h at initial sintering stage. A two-step sintering procedure was then used in the final sintering stage. In the first step, the tapes are sintered at 840-865 deg. C for 1 h. In the second step, they were sintered at 835 deg. C for 120 h. The results show that the first step sintering temperature has significant influence on the microstructure and the critical current density J c . The observed microstructures are consistent well with the different J c performances of the tapes first-step-sintered at different temperatures. The tape first-step-sintered at 850 deg. C, which has small secondary phases, stronger c-axis grain alignment, higher proportion of Bi-2223 phase, and no cracks, exhibits the highest J c value

  6. Two-step carbon coating of lithium vanadium phosphate as high-rate cathode for lithium-ion batteries

    Science.gov (United States)

    Kuang, Quan; Zhao, Yanming

    2012-10-01

    Carbon-coated Li3V2(PO4)3 was firstly prepared at 850 °C via two-step reaction method combined sol-gel and conventional solid-state synthesis by using VPO4/carbon as an intermediate. Two different carbon sources, citric acid and glucose as carbon additives in sequence, ultimately deduced double carbon-coated Li3V2(PO4)3 as a high-rate cathode material. The Li3V2(PO4)3/carbon with 4.39% residual carbon has a splendid electronic conductivity of 4.76×10-2 S cm-1. Even in the voltage window of 2.5-4.8 V, the Li3V2(PO4)3/carbon cathode can retain outstanding rate ability (170.4 mAh g-1 at 1.2 C, 101.9 mAh g-1 at 17 C), and no degradation is found after 120 C current rate. These phenomena show that the two-step carbon-coated Li3V2(PO4)3 can act as a fast charge-discharge cathode material for high-power Li-ion batteries. Furthermore, it's believed that this synthesize method can be easily transplanted to prepare other lithiated vanadium-based phosphates.

  7. Two-Step Hot-Compressed Water Treatment of Douglas Fir for Efficient Total Sugar Recovery by Enzymatic Hydrolysis

    Directory of Open Access Journals (Sweden)

    Hiroyuki Inoue

    2016-04-01

    Full Text Available The non-catalytic hydrothermal pretreatment of softwood is generally less effective for subsequent enzymatic hydrolysis. In this study, the efficacy of hot-compressed water (HCW treatment of Douglas fir was investigated between 180 °C and 260 °C, allowing solubilization of the cellulose components. The enzymatic digestibility of cellulosic residues increased significantly under HCW conditions > 250 °C, and the enhanced glucan digestibility was closely related to the decomposition of the cellulose component. Combination of the first-stage HCW treatment (220 °C, 5 min to recover hemicellulosic sugars with the second-stage HCW treatment (260 °C, 5 min to improve cellulose digestibility gave a total sugar recovery of 56.2% based on the dried raw materials. This yield was 1.4 times higher than that from the one-step HCW-treated sample (260 °C, 5 min. Additionally, an enzymatic hydrolysate from the two-step HCW-treated sample exceeded 90% of the ethanol fermentation yield based on the total sugars present in the hydrolysates. These results suggest the potential of the two-step HCW treatment of softwood as a pretreatment technology for efficient total sugar recovery and ethanol production.

  8. Web based health surveys: Using a Two Step Heckman model to examine their potential for population health analysis.

    Science.gov (United States)

    Morrissey, Karyn; Kinderman, Peter; Pontin, Eleanor; Tai, Sara; Schwannauer, Mathias

    2016-08-01

    In June 2011 the BBC Lab UK carried out a web-based survey on the causes of mental distress. The 'Stress Test' was launched on 'All in the Mind' a BBC Radio 4 programme and the test's URL was publicised on radio and TV broadcasts, and made available via BBC web pages and social media. Given the large amount of data created, over 32,800 participants, with corresponding diagnosis, demographic and socioeconomic characteristics; the dataset are potentially an important source of data for population based research on depression and anxiety. However, as respondents self-selected to participate in the online survey, the survey may comprise a non-random sample. It may be only individuals that listen to BBC Radio 4 and/or use their website that participated in the survey. In this instance using the Stress Test data for wider population based research may create sample selection bias. Focusing on the depression component of the Stress Test, this paper presents an easy-to-use method, the Two Step Probit Selection Model, to detect and statistically correct selection bias in the Stress Test. Using a Two Step Probit Selection Model; this paper did not find a statistically significant selection on unobserved factors for participants of the Stress Test. That is, survey participants who accessed and completed an online survey are not systematically different from non-participants on the variables of substantive interest. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. A Dynamic Range Enhanced Readout Technique with a Two-Step TDC for High Speed Linear CMOS Image Sensors

    Directory of Open Access Journals (Sweden)

    Zhiyuan Gao

    2015-11-01

    Full Text Available This paper presents a dynamic range (DR enhanced readout technique with a two-step time-to-digital converter (TDC for high speed linear CMOS image sensors. A multi-capacitor and self-regulated capacitive trans-impedance amplifier (CTIA structure is employed to extend the dynamic range. The gain of the CTIA is auto adjusted by switching different capacitors to the integration node asynchronously according to the output voltage. A column-parallel ADC based on a two-step TDC is utilized to improve the conversion rate. The conversion is divided into coarse phase and fine phase. An error calibration scheme is also proposed to correct quantization errors caused by propagation delay skew within −Tclk~+Tclk. A linear CMOS image sensor pixel array is designed in the 0.13 μm CMOS process to verify this DR-enhanced high speed readout technique. The post simulation results indicate that the dynamic range of readout circuit is 99.02 dB and the ADC achieves 60.22 dB SNDR and 9.71 bit ENOB at a conversion rate of 2 MS/s after calibration, with 14.04 dB and 2.4 bit improvement, compared with SNDR and ENOB of that without calibration.

  10. Modified two-step emulsion solvent evaporation technique for fabricating biodegradable rod-shaped particles in the submicron size range.

    Science.gov (United States)

    Safari, Hanieh; Adili, Reheman; Holinstat, Michael; Eniola-Adefeso, Omolola

    2018-05-15

    Though the emulsion solvent evaporation (ESE) technique has been previously modified to produce rod-shaped particles, it cannot generate small-sized rods for drug delivery applications due to the inherent coupling and contradicting requirements for the formation versus stretching of droplets. The separation of the droplet formation from the stretching step should enable the creation of submicron droplets that are then stretched in the second stage by manipulation of the system viscosity along with the surface-active molecule and oil-phase solvent. A two-step ESE protocol is evaluated where oil droplets are formed at low viscosity followed by a step increase in the aqueous phase viscosity to stretch droplets. Different surface-active molecules and oil phase solvents were evaluated to optimize the yield of biodegradable PLGA rods. Rods were assessed for drug loading via an imaging agent and vascular-targeted delivery application via blood flow adhesion assays. The two-step ESE method generated PLGA rods with major and minor axis down to 3.2 µm and 700 nm, respectively. Chloroform and sodium metaphosphate was the optimal solvent and surface-active molecule, respectively, for submicron rod fabrication. Rods demonstrated faster release of Nile Red compared to spheres and successfully targeted an inflamed endothelium under shear flow in vitro and in vivo. Copyright © 2018 Elsevier Inc. All rights reserved.

  11. Surface Activity of Sulfactin Recovered and Purified from Fermentation Broth Using a Two-Step Ultrafiltration (UF) Process

    International Nuclear Information System (INIS)

    Mohd Hafez Mohd Isa; Frazier, A.R.; Jauregi, P.

    2011-01-01

    B. subtilis under certain types of media and fermentation conditions can produce surfactant, a bio surfactant which belongs to the lipo peptide class. Surfactant has exceptional surfactant activity, and exhibits some interesting biological characteristics such as antibacterial activity, anti tumoral activity against ascites carcinoma cells, and a hypercholesterolaemia activity that inhibits cAMP phosphodiesterase, as well as having anti-HIV properties. A cost effective recovery and purification of surfactant from fermentation broth using a two-step ultrafiltration (UF) process has been developed in order to reduce the cost of surfactant production. In this study, competitive adsorption of surfactant and proteins at the air-water interface was studied using surface pressure measurements. Small volumes of bovine serum albumin (BSA) and β-casein solutions were added to the air-water interface on a Langmuir trough and allowed to stabilise before the addition of surfactant to the sub phase. Contrasting interfacial behaviour of proteins was observed with β-casein showing faster initial adsorption compared to BSA. On introduction of surfactant both proteins were displaced but a longer time were taken to displace β-casein. Overall the results showed surfactant were highly surface-active by forming a β-sheet structure at the air-water interface after reaching its critical micelle concentration (CMC) and were effective in removing both protein films, which can be explained following the orogenic mechanism. Results showed that the two-step UF process was effective to achieve high purity and fully functional surfactant. (author)

  12. Two Step Procedure Using a 1-D Slab Spectral Geometry in a Pebble Bed Reactor Core Analysis

    International Nuclear Information System (INIS)

    Lee, Hyun Chul; Kim, Kang Seog; Noh, Jae Man; Joo, Hyung Kook

    2005-01-01

    A strong spectral interaction between the core and the reflector has been one of the main concerns in the analysis of pebble bed reactor cores. To resolve this problem, VSOP adopted iteration between the spectrum calculation in a spectral zone and the global core calculation. In VSOP, the whole problem domain is divided into many spectral zones in which the fine group spectrum is calculated using bucklings for fast groups and albedos for thermal groups from the global core calculation. The resulting spectrum in each spectral zone is used to generate broad group cross sections of the spectral zone for the global core calculation. In this paper, we demonstrate a two step procedure in a pebble bed reactor core analysis. In the first step, we generate equivalent cross sections from a 1-D slab spectral geometry model with the help of the equivalence theory. The equivalent cross sections generated in this way include the effect of the spectral interaction between the core and the reflector. In the second step, we perform a diffusion calculation using the equivalent cross sections generated in the first step. A simple benchmark problem derived from the PMBR-400 Reactor was introduced to verify this approach. We compared the two step solutions with the Monte Carlo (MC) solutions for the problem

  13. Lateral stability of the spring-mass hopper suggests a two-step control strategy for running.

    Science.gov (United States)

    Carver, Sean G; Cowan, Noah J; Guckenheimer, John M

    2009-06-01

    This paper investigates the control of running gaits in the context of a spring loaded inverted pendulum model in three dimensions. Specifically, it determines the minimal number of steps required for an animal to recover from a perturbation to a specified gait. The model has four control inputs per step: two touchdown angles (azimuth and elevation) and two spring constants (compression and decompression). By representing the locomotor movement as a discrete-time return map and using the implicit function theorem we show that the number of recovery steps needed following a perturbation depends upon the goals of the control mechanism. When the goal is to follow a straight line, two steps are necessary and sufficient for small lateral perturbations. Multistep control laws have a larger number of control inputs than outputs, so solutions of the control problem are not unique. Additional constraints, referred to here as synergies, are imposed to determine unique control inputs for perturbations. For some choices of synergies, two-step control can be expressed as two iterations of its first step policy and designed so that recovery occurs in just one step for all perturbations for which one-step recovery is possible.

  14. Two-step reconstruction method using global optimization and conjugate gradient for ultrasound-guided diffuse optical tomography.

    Science.gov (United States)

    Tavakoli, Behnoosh; Zhu, Quing

    2013-01-01

    Ultrasound-guided diffuse optical tomography (DOT) is a promising method for characterizing malignant and benign lesions in the female breast. We introduce a new two-step algorithm for DOT inversion in which the optical parameters are estimated with the global optimization method, genetic algorithm. The estimation result is applied as an initial guess to the conjugate gradient (CG) optimization method to obtain the absorption and scattering distributions simultaneously. Simulations and phantom experiments have shown that the maximum absorption and reduced scattering coefficients are reconstructed with less than 10% and 25% errors, respectively. This is in contrast with the CG method alone, which generates about 20% error for the absorption coefficient and does not accurately recover the scattering distribution. A new measure of scattering contrast has been introduced to characterize benign and malignant breast lesions. The results of 16 clinical cases reconstructed with the two-step method demonstrates that, on average, the absorption coefficient and scattering contrast of malignant lesions are about 1.8 and 3.32 times higher than the benign cases, respectively.

  15. Use of a two-step ultrafiltration procedure to concentrate viral hemorrhagic septicemia virus (VHSV) in seawater.

    Science.gov (United States)

    Kim, Soo-Jin; Kim, Jong-Oh; Kim, Wi-Sik; Oh, Myung-Joo

    2015-11-01

    Viral hemorrhagic septicemia virus (VHSV) has been reported to be stable in both fresh as well as seawater, suggesting that VHSV exists in natural aquatic environments and might have an effect on the wild and cultured fish. However, VHSV is below the detectable limits of laboratory tests in natural seawater. In this study, a two-step ultrafiltration (UF) procedure was used to concentration of VHSV in seawater, providing samples that were tested for infectivity by cell culture and the presence of VHSV by quantitative reverse transcriptase PCR (qRT-PCR) methods. Overall, VHSV was approximately concentrated 100-1000 times in 1, 5 and 10 L, seawater volumes respectively: from 2.81×10(6) to 6.53×10(7)/mL and 10(3.3) to 10(3.8)TCID50/mL prior to the UF procedure, to 3.78×10(8), 1.16 × 10(11), and 9.12 × 10(10)/mL after the procedure. This is the first report of concentrating VHSV using an UF method that was specifically designed for seawater samples. In addition, the two-step UF procedure appears to be compatible with viral cell culture and qRT-PCR methods. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Homogeneous ZnO nanostructure arrays on GaAs substrates by two-step chemical bath synthesis

    International Nuclear Information System (INIS)

    Huang, Chun-Yuan; Wu, Tzung-Han; Cheng, Chiao-Yang; Su, Yan-Kuin

    2012-01-01

    ZnO nanostructures, including nanowires, nanorods, and nanoneedles, have been deposited on GaAs substrates by the two-step chemical bath synthesis. It was demonstrated that the O 2 -plasma treatment of GaAs substrates prior to the sol–gel deposition of seed layers was essential to conformally grow the nanostructures instead of 2D ZnO bunches and grains on the seed layers. Via adjusting the growth time and concentration of precursors, nanostructures with different average diameter (26–225 nm), length (0.98–2.29 μm), and density (1.9–15.3 × 10 9 cm −2 ) can be obtained. To the best of our knowledge, this is the first demonstration of ZnO nanostructure arrays grown on GaAs substrates by the two-step chemical bath synthesis. As an anti-reflection layer on GaAs-based solar cells, the array of ZnO nanoneedles with an average diameter of 125 nm, a moderate length of 2.29 μm, and the distribution density of 9.8 × 10 9 cm −2 has increased the power conversion efficiency from 7.3 to 12.2 %, corresponding to a 67 % improvement.

  17. Two-Step Multi-Physics Analysis of an Annular Linear Induction Pump for Fission Power Systems

    Science.gov (United States)

    Geng, Steven M.; Reid, Terry V.

    2016-01-01

    One of the key technologies associated with fission power systems (FPS) is the annular linear induction pump (ALIP). ALIPs are used to circulate liquid-metal fluid for transporting thermal energy from the nuclear reactor to the power conversion device. ALIPs designed and built to date for FPS project applications have not performed up to expectations. A unique, two-step approach was taken toward the multi-physics examination of an ALIP using ANSYS Maxwell 3D and Fluent. This multi-physics approach was developed so that engineers could investigate design variations that might improve pump performance. Of interest was to determine if simple geometric modifications could be made to the ALIP components with the goal of increasing the Lorentz forces acting on the liquid-metal fluid, which in turn would increase pumping capacity. The multi-physics model first calculates the Lorentz forces acting on the liquid metal fluid in the ALIP annulus. These forces are then used in a computational fluid dynamics simulation as (a) internal boundary conditions and (b) source functions in the momentum equations within the Navier-Stokes equations. The end result of the two-step analysis is a predicted pump pressure rise that can be compared with experimental data.

  18. Catalysis. Innovative applications in petrochemistry and refining. Preprints

    Energy Technology Data Exchange (ETDEWEB)

    Ernst, S.; Balfanz, U.; Jess, A.; Lercher, J.A.; Lichtscheidl, J.; Marchionna, M.; Nees, F.; Santacesaria, E. (eds.)

    2011-07-01

    Within the DGMK conference at 4th to 6th October, 2011 in Dresden (Federal Republic of Germany) the following lectures were held: (1) Developing linear-alpha-olefins technology - From laboratory to a commercial plant (A. Meiswinkel); (2) New developments in oxidation catalysis (F. Rosowski); (3) Study of the performance of vanadium based catalysts prepared by grafting in the oxidative dehydrogenation of propane (E. Santacesaria); (4) Hydrocracking for oriented conversion of heavy oils: recent trends for catalyst development (F. Bertoncini); (5) Acidic ionic liquids for n-alkane isomerization in a liquid-liquid or slurry-phase reaction mode (C. Meyer); (6) Dual catalyst system for the hydrocracking of heavy oils and residues (G. Bellussi); (7) Understanding hydrodenitrogenation on novel unsupported sulphide Mo-W-Ni catalysts (J. Hein); (8) Hydrocracking of ethyllaurate on bifunctional micro-/mesoporous composite materials (M. Adam); (9) Catalytic dehydration of ethanol to ethylene (Ying Zhu); (10) The Evonik-Uhde HPPO process for propylene oxide production (B. Jaeger); (11) A green two-step process for adipic acid production from cyclohexene: A study on parameters affecting selectivity (F. Cavani); (12) DISY: The direct synthesis of hydrogen peroxide, a bridge for innovative applications (R, Buzzoni); (13) Solid catalyst with ionic liquid layer (SCILL) - A concept to improve the selectivity of selective hydrogenations (A. Jess); (14) Co-Zn-Al based hydrotalcites as catalysts for Fischer-Tropsch process (C.L. Bianchi); (15) Honeycomb supports with high thermal conductivity for the Fischer-Tropsch synthesis (C.G. Visconti); (16) How to make Fischer-Tropsch catalyst scale-up fully reliable (L. Fischer); (17) New developments in FCC catalysis (C.P. Kelkar); (18) The potential of medium-pore zeolites for improved propene yields from catalytic cracking (F. Bager).

  19. In situ synthesis carbonated hydroxyapatite layers on enamel slices with acidic amino acids by a novel two-step method

    International Nuclear Information System (INIS)

    Wu, Xiaoguang; Zhao, Xu; Li, Yi; Yang, Tao; Yan, Xiujuan; Wang, Ke

    2015-01-01

    In situ fabrication of carbonated hydroxyapatite (CHA) remineralization layer on an enamel slice was completed in a novel, biomimetic two-step method. First, a CaCO 3 layer was synthesized on the surface of demineralized enamel using an acidic amino acid (aspartic acid or glutamate acid) as a soft template. Second, at the same concentration of the acidic amino acid, rod-like carbonated hydroxyapatite was produced with the CaCO 3 layer as a sacrificial template and a reactant. The morphology, crystallinity and other physicochemical properties of the crystals were characterized using field emission scanning electron microscopy (FESEM), Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD) and energy-dispersive X-ray analysis (EDAX), respectively. Acidic amino acid could promote the uniform deposition of hydroxyapatite with rod-like crystals via absorption of phosphate and carbonate ions from the reaction solution. Moreover, compared with hydroxyapatite crystals coated on the enamel when synthesized by a one-step method, the CaCO 3 coating that was synthesized in the first step acted as an active bridge layer and sacrificial template. It played a vital role in orienting the artificial coating layer through the template effect. The results show that the rod-like carbonated hydroxyapatite crystals grow into bundles, which are similar in size and appearance to prisms in human enamel, when using the two-step method with either aspartic acid or acidic glutamate (20.00 mmol/L). - Graphical abstract: FESEM images of enamel slices etched for 60 s and repaired by the two-step method with Glu concentration of 20.00 mmol/L. (A) The boundary (dotted line) of the repaired areas (b) and unrepaired areas (a). (Some selected areas of etched enamel slices were coated with a nail polish before the reaction, which was removed by acetone after the reaction); (B) high magnification image of Ga, (C) high magnification image of Gb. In situ fabrication of carbonated

  20. In situ synthesis carbonated hydroxyapatite layers on enamel slices with acidic amino acids by a novel two-step method

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Xiaoguang [Department of Pediatric Dentistry, The Hospital of Stomatology, Jilin University, Changchun 130021 (China); Zhao, Xu [College of Chemistry, Jilin University, Changchun 130021 (China); Li, Yi, E-mail: lyi99@jlu.edu.cn [Department of Pediatric Dentistry, The Hospital of Stomatology, Jilin University, Changchun 130021 (China); Yang, Tao [Department of Stomatology, Children' s Hospital of Changchun, 130051 (China); Yan, Xiujuan; Wang, Ke [Department of Pediatric Dentistry, The Hospital of Stomatology, Jilin University, Changchun 130021 (China)

    2015-09-01

    In situ fabrication of carbonated hydroxyapatite (CHA) remineralization layer on an enamel slice was completed in a novel, biomimetic two-step method. First, a CaCO{sub 3} layer was synthesized on the surface of demineralized enamel using an acidic amino acid (aspartic acid or glutamate acid) as a soft template. Second, at the same concentration of the acidic amino acid, rod-like carbonated hydroxyapatite was produced with the CaCO{sub 3} layer as a sacrificial template and a reactant. The morphology, crystallinity and other physicochemical properties of the crystals were characterized using field emission scanning electron microscopy (FESEM), Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD) and energy-dispersive X-ray analysis (EDAX), respectively. Acidic amino acid could promote the uniform deposition of hydroxyapatite with rod-like crystals via absorption of phosphate and carbonate ions from the reaction solution. Moreover, compared with hydroxyapatite crystals coated on the enamel when synthesized by a one-step method, the CaCO{sub 3} coating that was synthesized in the first step acted as an active bridge layer and sacrificial template. It played a vital role in orienting the artificial coating layer through the template effect. The results show that the rod-like carbonated hydroxyapatite crystals grow into bundles, which are similar in size and appearance to prisms in human enamel, when using the two-step method with either aspartic acid or acidic glutamate (20.00 mmol/L). - Graphical abstract: FESEM images of enamel slices etched for 60 s and repaired by the two-step method with Glu concentration of 20.00 mmol/L. (A) The boundary (dotted line) of the repaired areas (b) and unrepaired areas (a). (Some selected areas of etched enamel slices were coated with a nail polish before the reaction, which was removed by acetone after the reaction); (B) high magnification image of Ga, (C) high magnification image of Gb. In situ fabrication of

  1. Surface science and heterogeneous catalysis

    International Nuclear Information System (INIS)

    Somorjai, G.A.

    1980-05-01

    The catalytic reactions studied include hydrocarbon conversion over platinum, the transition metal-catalyzed hydrogenation of carbon monoxide, and the photocatalyzed dissociation of water over oxide surfaces. The method of combined surface science and catalytic studies is similar to those used in synthetic organic chemistry. The single-crystal models for the working catalyst are compared with real catalysts by comparing the rates of cyclopropane ring opening on platinum and the hydrogenation of carbon monoxide on rhodium single crystal surface with those on practical commercial catalyst systems. Excellent agreement was obtained for these reactions. This document reviews what was learned about heterogeneous catalysis from these surface science approaches over the past 15 years and present models of the active catalyst surface

  2. Enzymatic modification of natural and synthetic polymers using lipases and proteases

    Science.gov (United States)

    Chakraborty, Soma

    Enzymatic modification of natural/synthetic polymers [starch nanoparticles, poly (n-alkyl acrylates) and poly(vinyl formamide)] was studied. Enzymes used for catalysis were lipases and proteases. Starch nanoparticles (40nm diameter) were incorporated into AOT-coated reverse micelles. Reactions performed with the acylating agents vinyl stearate, epsilon-caprolactone and maleic anhydride in toluene in presence of Novozyme-435 at 40°C for 36h gave products with degrees of substitution of 0.8, 0.6 and 0.4 respectively. DEPT-135 NMR spectra revealed that the modification occurred regioselectively at the C-6 position of the glucose units. Infrared microspectroscopy showed that the surfactant coated starch nanoparticles diffuse into pores of Novozyme-435 beads, coming in close proximity with CALB to promote modification. The modified products retained nanoscale dimensions. Catalysis of amide bond formation between a low molar mass amine and ester side groups of poly(n-alkyl acrylates)[poly(ethyl acrylate), poly(methyl acrylate) and poly(butyl acrylate)] was also examined. The nucleophiles were mono and diamines. Among the poly(n-alkyl acrylates) and the lipases studied, poly(ethyl acrylate) was the preferred substrate and Novozyme-435 the most active lipase. Poly(ethyl acrylate) in 80% by-volume toluene was reacted with 1 equivalent per repeat unit of hexyl amine at 70°C in presence of Novozyme-435. The product contained 10.6 mol% amide groups. Attempts to increase the amidation beyond 10--11 mol% by increasing the reaction time or use of fresh enzyme were unsuccessful, showing that poly(ethylacrylate-co-10mol%hexylacrylamide) is a poor substrate for further acylation. When chiral amines ([R,S]-alpha-methyl benzylamine, [R,S]-beta-methyl phenyl amine) were used as nucleophiles, Novozyme-435 enantioselectively catalyzed amidation of poly(ethyl acrylate). Poly(vinyl formamide), P(VfAm) by acid or base-catalyzed hydrolysis leads to poly(vinylamine), P(VAm), and

  3. Tandem catalysis: a new approach to polymers.

    Science.gov (United States)

    Robert, Carine; Thomas, Christophe M

    2013-12-21

    The creation of polymers by tandem catalysis represents an exciting frontier in materials science. Tandem catalysis is one of the strategies used by Nature for building macromolecules. Living organisms generally synthesize macromolecules by in vivo enzyme-catalyzed chain growth polymerization reactions using activated monomers that have been formed within cells during complex metabolic processes. However, these biological processes rely on highly complex biocatalysts, thus limiting their industrial applications. In order to obtain polymers by tandem catalysis, homogeneous and enzyme catalysts have played a leading role in the last two decades. In the following feature article, we will describe selected published efforts to achieve these research goals.

  4. Supported Ionic Liquid Phase (SILP) catalysis

    DEFF Research Database (Denmark)

    Riisager, Anders; Fehrmann, Rasmus; Haumann, Marco

    2006-01-01

    Applications of ionic liquids to replace conventional solvents in homogeneous transition-metal catalysis have increased significantly during the last decade. Biphasic ionic liquid/organic liquid systems offer advantages with regard to product separation, catalyst stability, and recycling...... but utilise in the case of fast chemical reactions only a small amount of expensive ionic liquid and catalyst. The novel Supported Ionic Liquid Phase (SILP) catalysis concept overcomes these drawbacks and allows the use of fixed-bed reactors for continuous reactions. In this Microreview the SILP catalysis...

  5. A two-step crushed lava rock filter unit for grey water treatment at household level in an urban slum.

    Science.gov (United States)

    Katukiza, A Y; Ronteltap, M; Niwagaba, C B; Kansiime, F; Lens, P N L

    2014-01-15

    Decentralised grey water treatment in urban slums using low-cost and robust technologies offers opportunities to minimise public health risks and to reduce environmental pollution caused by the highly polluted grey water i.e. with a COD and N concentration of 3000-6000 mg L(-1) and 30-40 mg L(-1), respectively. However, there has been very limited action research to reduce the pollution load from uncontrolled grey water discharge by households in urban slums. This study was therefore carried out to investigate the potential of a two-step filtration process to reduce the grey water pollution load in an urban slum using a crushed lava rock filter, to determine the main filter design and operation parameters and the effect of intermittent flow on the grey water effluent quality. A two-step crushed lava rock filter unit was designed and implemented for use by a household in the Bwaise III slum in Kampala city (Uganda). It was monitored at a varying hydraulic loading rate (HLR) of 0.5-1.1 m d(-1) as well as at a constant HLR of 0.39 m d(-1). The removal efficiencies of COD, TP and TKN were, respectively, 85.9%, 58% and 65.5% under a varying HLR and 90.5%, 59.5% and 69%, when operating at a constant HLR regime. In addition, the log removal of Escherichia coli, Salmonella spp. and total coliforms was, respectively, 3.8, 3.2 and 3.9 under the varying HLR and 3.9, 3.5 and 3.9 at a constant HLR. The results show that the use of a two-step filtration process as well as a lower constant HLR increased the pollutant removal efficiencies. Further research is needed to investigate the feasibility of adding a tertiary treatment step to increase the nutrients and microorganisms removal from grey water. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Modification of oligo-Ricinoleic Acid and Its Derivatives with 10-Undecenoic Acid via Lipase-Catalyzed Esterification

    Directory of Open Access Journals (Sweden)

    M. Claudia Montiel

    2012-04-01

    Full Text Available Lipases were employed under solvent-free conditions to conjugate oligo-ricinoleic acid derivatives with 10-undecenoic acid, to incorporate a reactive terminal double bond into the resultant product. First, undecenoic acid was covalently attached to oligo-ricinoleic acid using immobilized Candida antarctica lipase (CAL at a 30% yield. Thirty percent conversion also occurred for CAL-catalyzed esterification between undecenoic acid and biocatalytically-prepared polyglycerol polyricinoleate (PGPR, with attachment of undecenoic acid occurring primarily at free hydroxyls of the polyglycerol moiety. The synthesis of oligo-ricinoleyl-, undecenoyl- structured triacylglycerols comprised two steps. The first step, the 1,3-selective lipase-catalyzed interesterification of castor oil with undecenoic acid, occurred successfully. The second step, the CAL-catalyzed reaction between ricinoleyl-, undecenoyl structured TAG and ricinoleic acid, yielded approximately 10% of the desired structured triacylglycerols (TAG; however, a significant portion of the ricinoleic acid underwent self-polymerization as a side-reaction. The employment of gel permeation chromatography, normal phase HPLC, NMR, and acid value measurements was effective for characterizing the reaction pathways and products that formed.

  7. Role of the NC-loop in catalytic activity and stability in lipase from Fervidobacterium changbaicum.

    Directory of Open Access Journals (Sweden)

    Binchun Li

    Full Text Available Flexible NC-loops between the catalytic domain and the cap domain of the α/β hydrolase fold enzymes show remarkable diversity in length, sequence, and configuration. Recent investigations have suggested that the NC-loop might be involved in catalysis and substrate recognition in many enzymes from the α/β hydrolase fold superfamily. To foster a deep understanding of its role in catalysis, stability, and divergent evolution, we here systemically investigated the function of the NC-loop (residues 131-151 in a lipase (FClip1 from thermophilic bacterium Fervidobacterium changbaicum by loop deletion, alanine-scanning mutagenesis and site-directed mutagenesis. We found that the upper part of the NC-loop (residues 131-138 was of great importance to enzyme catalysis. Single substitutions in this region could fine-tune the activity of FClip1 as much as 41-fold, and any deletions from this region rendered the enzyme completely inactive. The lower part of the NC-loop (residues 139-151 was capable of enduring extensive deletions without loss of activity. The shortened mutants in this region were found to show both improved activity and increased stability simultaneously. We therefore speculated that the NC-loop, especially the lower part, would be a perfect target for enzyme engineering to optimize the enzymatic properties, and might present a hot zone for the divergent evolution of α/β hydrolases. Our findings may provide an opportunity for better understanding of the mechanism of divergent evolution in the α/β hydrolase fold superfamily, and may also guide the design of novel biocatalysts for industrial applications.

  8. Tailoring structures through two-step annealing process in nanostructured aluminum produced by accumulative roll-bonding

    DEFF Research Database (Denmark)

    Kamikawa, Naoya; Huang, Xiaoxu; Hansen, Niels

    2008-01-01

    temperature before annealing at high temperature. By this two-step process, the structure is homogenized and the stored energy is reduced significantly during the first annealing step. As an example, high-purity aluminum has been deformed to a total reduction of 98.4% (equivalent strain of 4.......8) by accumulative roll-bonding at room temperature. Isochronal annealing for 0.5 h of the deformed samples shows the occurrence of recrystallization at 200 °C and above. However, when introducing an annealing step for 6 h at 175 °C, no significant recrystallization is observed and relatively homogeneous structures...... are obtained when the samples afterwards are annealed at higher temperatures up to 300 °C. To underpin these observations, the structural evolution has been characterized by transmission electron microscopy, showing that significant annihilation of high-angle boundaries, low-angle dislocation boundaries...

  9. Hybrid pseudomonads engineered by two-step homologous recombination acquire novel degradation abilities toward aromatics and polychlorinated biphenyls

    Energy Technology Data Exchange (ETDEWEB)

    Suenaga, Hikaru [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba (Japan). Bioproduction Research Inst.; Nonaka, Kazuhiko; Goto, Masatoshi [Kyushu Univ., Fukuoka (Japan). Dept. of Bioscience and Biotechnology; Fujihara, Hidehiko; Furukawa, Kensuke [Beppu Univ. (Japan). Dept. of Fermentation and Food Science

    2010-10-15

    Pseudomonas pseudoalcaligenes KF707 possesses a chromosomally encoded bph gene cluster responsible for the catabolism of biphenyl and polychlorinated biphenyls. Previously, we constructed chimeric versions of the bphA1 gene, which encodes a large subunit of biphenyl dioxygenase, by using DNA shuffling between bphA1 genes from P. pseudoalcaligenes KF707 and Burkholderia xenovorans LB400. In this study, we demonstrate replacement of the bphA1 gene with chimeric bphA1 sequence within the chromosomal bph gene cluster by two-step homologous recombination. Notably, some of the hybrid strains acquired enhanced and/or expanded degradation capabilities for specific aromatic compounds, including single aromatic hydrocarbons and polychlorinated biphenyls. (orig.)

  10. Phase gradient algorithm based on co-axis two-step phase-shifting interferometry and its application

    Science.gov (United States)

    Wang, Yawei; Zhu, Qiong; Xu, Yuanyuan; Xin, Zhiduo; Liu, Jingye

    2017-12-01

    A phase gradient method based on co-axis two-step phase-shifting interferometry, is used to reveal the detailed information of a specimen. In this method, the phase gradient distribution can only be obtained by calculating both the first-order derivative and the radial Hilbert transformation of the intensity difference between two phase-shifted interferograms. The feasibility and accuracy of this method were fully verified by the simulation results for a polystyrene sphere and a red blood cell. The empirical results demonstrated that phase gradient is sensitive to changes in the refractive index and morphology. Because phase retrieval and tedious phase unwrapping are not required, the calculation speed is faster. In addition, co-axis interferometry has high spatial resolution.

  11. Separation of uranium and rare earth elements from Rirang ore leach solution by two-step precipitation

    International Nuclear Information System (INIS)

    Sradjono; Erni Rifandriyah, A.; Zahardi

    1995-01-01

    Separation of uranium and rare-earth elements from Rirang ore leach solution was carried out through a two-step precipitation. Several condition affecting the separation processes were examined including solution pH, reagent concentration, and reaction prepitation time. Optimum conditions for the first and second precipitation steps include adjustment of precipitation pH to 1.3 and 2.3, respectively by the addition of 7.3% of NH 4 OH solution and allowing 60 minutes precipitation/reaction time. Based on the conditions, about 6% of Th, 3% of U, 0.9% of PO 4 3- , and none of RE were recovered in the first precipitation step meanwhile, about 99% of RE, 55% of U, 76% of PO 4 3- , and of the Th were recovered in the second step. (author). 3 refs. 4 tabs. 4 figs

  12. Cryptosystem based on two-step phase-shifting interferometry and the RSA public-key encryption algorithm

    Science.gov (United States)

    Meng, X. F.; Peng, X.; Cai, L. Z.; Li, A. M.; Gao, Z.; Wang, Y. R.

    2009-08-01

    A hybrid cryptosystem is proposed, in which one image is encrypted to two interferograms with the aid of double random-phase encoding (DRPE) and two-step phase-shifting interferometry (2-PSI), then three pairs of public-private keys are utilized to encode and decode the session keys (geometrical parameters, the second random-phase mask) and interferograms. In the stage of decryption, the ciphered image can be decrypted by wavefront reconstruction, inverse Fresnel diffraction, and real amplitude normalization. This approach can successfully solve the problem of key management and dispatch, resulting in increased security strength. The feasibility of the proposed cryptosystem and its robustness against some types of attack are verified and analyzed by computer simulations.

  13. Study the effect of striping in two-step anodizing process on pore arrangement of nano-porous alumina

    International Nuclear Information System (INIS)

    Rahimi, M.H.; Saramad, S.; Tabaian, S.H.; Marashi, S.P.; Zolfaghari, A.; Mohammadalinezhad, M.

    2009-01-01

    Two-step anodic oxidation of aluminum is generally employed to produce the ordered porous anodized alumina (PAA). Dissolving away (striping) the oxide film after the first anodizing step plays a key role in the final arrangement of nano-pores. In this work, different striping durations between 1 and 6 h were applied to the sample that was initially anodized at a constant voltage of 40 V at 17 deg. C for 15 h. The striping duration of 3 h was realized as the optimum time for achieving the best ordering degree for the pores. Scanning electron microscopy (SEM) was used during and at the end of the process to examine the cross section and finishing surface of the specimens. Linear-angular fast Fourier transform (LA-FFT), an in-house technique based on MATLAB software, was employed to assess the ordering degree of the anodized samples.

  14. Study the effect of striping in two-step anodizing process on pore arrangement of nano-porous alumina

    Energy Technology Data Exchange (ETDEWEB)

    Rahimi, M.H. [Department of Mining and Metallurgical Engineering, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Saramad, S., E-mail: ssaramad@aut.ac.ir [Department of Physics, Amirkabir University of Technology, Hafez Avenue, Tehran (Iran, Islamic Republic of); Tabaian, S.H.; Marashi, S.P. [Department of Mining and Metallurgical Engineering, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Zolfaghari, A. [Chemistry and Chemical Engineering Research Centre of Iran, Tehran (Iran, Islamic Republic of); Mohammadalinezhad, M. [Department of Mining and Metallurgical Engineering, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of)

    2009-10-15

    Two-step anodic oxidation of aluminum is generally employed to produce the ordered porous anodized alumina (PAA). Dissolving away (striping) the oxide film after the first anodizing step plays a key role in the final arrangement of nano-pores. In this work, different striping durations between 1 and 6 h were applied to the sample that was initially anodized at a constant voltage of 40 V at 17 deg. C for 15 h. The striping duration of 3 h was realized as the optimum time for achieving the best ordering degree for the pores. Scanning electron microscopy (SEM) was used during and at the end of the process to examine the cross section and finishing surface of the specimens. Linear-angular fast Fourier transform (LA-FFT), an in-house technique based on MATLAB software, was employed to assess the ordering degree of the anodized samples.

  15. Superthermostability of nanoscale TIC-reinforced copper alloys manufactured by a two-step ball-milling process

    Science.gov (United States)

    Wang, Fenglin; Li, Yunping; Xu, Xiandong; Koizumi, Yuichiro; Yamanaka, Kenta; Bian, Huakang; Chiba, Akihiko

    2015-12-01

    A Cu-TiC alloy, with nanoscale TiC particles highly dispersed in the submicron-grained Cu matrix, was manufactured by a self-developed two-step ball-milling process on Cu, Ti and C powders. The thermostability of the composite was evaluated by high-temperature isothermal annealing treatments, with temperatures ranging from 727 to 1273 K. The semicoherent nanoscale TiC particles with Cu matrix, mainly located along the grain boundaries, were found to exhibit the promising trait of blocking grain boundary migrations, which leads to a super-stabilized microstructures up to approximately the melting point of copper (1223 K). Furthermore, the Cu-TiC alloys after annealing at 1323 K showed a slight decrease in Vickers hardness as well as the duplex microstructure due to selective grain growth, which were discussed in terms of hardness contributions from various mechanisms.

  16. Climatic change on the Gulf of Fonseca (Central America) using two-step statistical downscaling of CMIP5 model outputs

    Science.gov (United States)

    Ribalaygua, Jaime; Gaitán, Emma; Pórtoles, Javier; Monjo, Robert

    2018-05-01

    A two-step statistical downscaling method has been reviewed and adapted to simulate twenty-first-century climate projections for the Gulf of Fonseca (Central America, Pacific Coast) using Coupled Model Intercomparison Project (CMIP5) climate models. The downscaling methodology is adjusted after looking for good predictor fields for this area (where the geostrophic approximation fails and the real wind fields are the most applicable). The method's performance for daily precipitation and maximum and minimum temperature is analysed and revealed suitable results for all variables. For instance, the method is able to simulate the characteristic cycle of the wet season for this area, which includes a mid-summer drought between two peaks. Future projections show a gradual temperature increase throughout the twenty-first century and a change in the features of the wet season (the first peak and mid-summer rainfall being reduced relative to the second peak, earlier onset of the wet season and a broader second peak).

  17. Effects of a modular two-step ozone-water and annealing process on silicon carbide graphene

    Energy Technology Data Exchange (ETDEWEB)

    Webb, Matthew J., E-mail: matthew.webb@cantab.net; Lundstedt, Anna; Grennberg, Helena [Department of Chemistry—BMC, Uppsala University, Box 576, SE-751 23 Uppsala (Sweden); Polley, Craig; Niu, Yuran; Zakharov, Alexei A.; Balasubramanian, Thiagarajan [MAX IV Laboratory, Lund University, 22100 Lund (Sweden); Dirscherl, Kai [DFM—Danish Fundamental Metrology, Matematiktorvet 307, DK-2800 Lyngby (Denmark); Burwell, Gregory; Guy, Owen J. [College of Engineering, Faraday Tower, Singleton Park, Swansea University, Swansea SA2 8PP (United Kingdom); Palmgren, Pål [VG Scienta Scientific AB, Box 15120, Vallongatan 1, SE-750 15 Uppsala (Sweden); Yakimova, Rositsa [Department of Physics, Chemistry, and Biology, Linköping University, SE-581 83 Linköping (Sweden)

    2014-08-25

    By combining ozone and water, the effect of exposing epitaxial graphene on silicon carbide to an aggressive wet-chemical process has been evaluated after high temperature annealing in ultra high vacuum. The decomposition of ozone in water produces a number of oxidizing species, however, despite long exposure times to the aqueous-ozone environment, no graphene oxide was observed after the two-step process. The systems were comprehensively characterized before and after processing using Raman spectroscopy, core level photoemission spectroscopy, and angle resolved photoemission spectroscopy together with low energy electron diffraction, low energy electron microscopy, and atomic force microscopy. In spite of the chemical potential of the aqueous-ozone reaction environment, the graphene domains were largely unaffected raising the prospect of employing such simple chemical and annealing protocols to clean or prepare epitaxial graphene surfaces.

  18. A cascaded two-step Kalman filter for estimation of human body segment orientation using MEMS-IMU.

    Science.gov (United States)

    Zihajehzadeh, S; Loh, D; Lee, M; Hoskinson, R; Park, E J

    2014-01-01

    Orientation of human body segments is an important quantity in many biomechanical analyses. To get robust and drift-free 3-D orientation, raw data from miniature body worn MEMS-based inertial measurement units (IMU) should be blended in a Kalman filter. Aiming at less computational cost, this work presents a novel cascaded two-step Kalman filter orientation estimation algorithm. Tilt angles are estimated in the first step of the proposed cascaded Kalman filter. The estimated tilt angles are passed to the second step of the filter for yaw angle calculation. The orientation results are benchmarked against the ones from a highly accurate tactical grade IMU. Experimental results reveal that the proposed algorithm provides robust orientation estimation in both kinematically and magnetically disturbed conditions.

  19. Two-step infiltration of aluminum melts into Al-Ti-B4C-CuO powder mixture pellets

    Science.gov (United States)

    Zhang, Jingjing; Lee, Jung-Moo; Cho, Young-Hee; Kim, Su-Hyeon; Yu, Huashun

    2016-03-01

    Aluminum matrix composites with a high volume fraction of B4C and TiB2 were fabricated by a novel processing technique - a quick spontaneous infiltration process. The process combines a pressureless infiltration with the combustion reaction of Al-Ti-B4C-CuO in molten aluminum. The process is realized in a simple and economical way in which the whole process is performed in air in a few minutes. To verify the rapidity of the process, the infiltration kinetics was calculated based on the Washburn equation in which melt flows into a porous skeleton. However, there was a noticeable deviation from the calculated results with the experimental results. Considering the cross-sections of the samples at different processing times, a new infiltration model (two step infiltration) consisting of macro-infiltration and micro-infiltration is suggested. The calculated kinetics results in light of the proposed model agree well with the experimental results.

  20. Study the effect of striping in two-step anodizing process on pore arrangement of nano-porous alumina

    Science.gov (United States)

    Rahimi, M. H.; Saramad, S.; Tabaian, S. H.; Marashi, S. P.; Zolfaghari, A.; Mohammadalinezhad, M.

    2009-10-01

    Two-step anodic oxidation of aluminum is generally employed to produce the ordered porous anodized alumina (PAA). Dissolving away (striping) the oxide film after the first anodizing step plays a key role in the final arrangement of nano-pores. In this work, different striping durations between 1 and 6 h were applied to the sample that was initially anodized at a constant voltage of 40 V at 17 °C for 15 h. The striping duration of 3 h was realized as the optimum time for achieving the best ordering degree for the pores. Scanning electron microscopy (SEM) was used during and at the end of the process to examine the cross section and finishing surface of the specimens. Linear-angular fast Fourier transform (LA-FFT), an in-house technique based on MATLAB software, was employed to assess the ordering degree of the anodized samples.

  1. Two-step production of monoamines in monoenzymatic cells in the spinal cord: a different control strategy of neurotransmitter supply?

    DEFF Research Database (Denmark)

    Zhang, Mengliang

    2016-01-01

    Monoamine neurotransmitters play an important role in the modulation of sensory, motor and autonomic functions in the spinal cord. Although traditionally it is believed that in mammalian spinal cord, monoamine neurotransmitters mainly originate from the brain, accumulating evidence indicates...... that especially when the spinal cord is injured, they can also be produced in the spinal cord. In this review, I will present evidence for a possible pathway for two-step synthesis of dopamine and serotonin in the spinal cord. Published data from different sources and unpublished data from my own ongoing projects...... that dopamine and serotonin could be synthesized sequentially in two monoenzymatic cells in the spinal cord via a TH-AADC and a TPH-AADC cascade respectively. The monoamines synthesized through this pathway may compensate for lost neurotransmitters following spinal cord injury and also may play specific roles...

  2. Two-step simulation of velocity and passive scalar mixing at high Schmidt number in turbulent jets

    Science.gov (United States)

    Rah, K. Jeff; Blanquart, Guillaume

    2016-11-01

    Simulation of passive scalar in the high Schmidt number turbulent mixing process requires higher computational cost than that of velocity fields, because the scalar is associated with smaller length scales than velocity. Thus, full simulation of both velocity and passive scalar with high Sc for a practical configuration is difficult to perform. In this work, a new approach to simulate velocity and passive scalar mixing at high Sc is suggested to reduce the computational cost. First, the velocity fields are resolved by Large Eddy Simulation (LES). Then, by extracting the velocity information from LES, the scalar inside a moving fluid blob is simulated by Direct Numerical Simulation (DNS). This two-step simulation method is applied to a turbulent jet and provides a new way to examine a scalar mixing process in a practical application with smaller computational cost. NSF, Samsung Scholarship.

  3. Two-Step Cycle for Producing Multiple Anodic Aluminum Oxide (AAO) Films with Increasing Long-Range Order.

    Science.gov (United States)

    Choudhary, Eric; Szalai, Veronika

    2016-01-01

    Nanoporous anodic aluminum oxide (AAO) membranes are being used for an increasing number of applications. However, the original two-step anodization method in which the first anodization is sacrificial to pre-pattern the second is still widely used to produce them. This method provides relatively low throughput and material utilization as half of the films are discarded. An alternative scheme that relies on alternating anodization and cathodic delamination is demonstrated that allows for the fabrication of several AAO films with only one sacrificial layer thus greatly improving total aluminum to alumina yield. The thickness for which the cathodic delamination performs best to yield full, unbroken AAO sheets is around 85 μm. Additionally, an image analysis method is used to quantify the degree of long-range ordering of the unit cells in the AAO films which was found to increase with each successive iteration of the fabrication cycle.

  4. Two-step digit-set-restricted modified signed-digit addition-subtraction algorithm and its optoelectronic implementation.

    Science.gov (United States)

    Qian, F; Li, G; Ruan, H; Jing, H; Liu, L

    1999-09-10

    A novel, to our knowledge, two-step digit-set-restricted modified signed-digit (MSD) addition-subtraction algorithm is proposed. With the introduction of the reference digits, the operand words are mapped into an intermediate carry word with all digits restricted to the set {1, 0} and an intermediate sum word with all digits restricted to the set {0, 1}, which can be summed to form the final result without carry generation. The operation can be performed in parallel by use of binary logic. An optical system that utilizes an electron-trapping device is suggested for accomplishing the required binary logic operations. By programming of the illumination of data arrays, any complex logic operations of multiple variables can be realized without additional temporal latency of the intermediate results. This technique has a high space-bandwidth product and signal-to-noise ratio. The main structure can be stacked to construct a compact optoelectronic MSD adder-subtracter.

  5. Flexible fabrication of biomimetic compound eye array via two-step thermal reflow of simply pre-modeled hierarchic microstructures

    Science.gov (United States)

    Huang, Shengzhou; Li, Mujun; Shen, Lianguan; Qiu, Jinfeng; Zhou, Youquan

    2017-06-01

    A flexible fabrication method for the biomimetic compound eye (BCE) array is proposed. In this method, a triple-layer sandwich-like coating configuration was introduced, and the required hierarchic microstructures are formed with a simple single-scan exposure in maskless digital lithography. Taking advantage of the difference of glass transition point (Tg) between photoresists of each layer, the pre-formed hierarchic microstructures are in turn reflowed to the curved substrate and the BCE ommatidia in a two-step thermal reflow process. To avoid affecting the spherical substrate formed in the first thermal reflow, a non-contact strategy was proposed in the second reflow process. The measurement results were in good agreement with the designed BCE profiles. Results also showed that the fabricated BCE had good performances in optical test. The presented method is flexible, convenient, low-cost and can easily adapt to the fabrications of other optical elements with hierarchic microstructures.

  6. Internal friction behaviors of Ni-Mn-In magnetic shape memory alloy with two-step structural transformation

    Directory of Open Access Journals (Sweden)

    Zhen-ni Zhou

    2017-06-01

    Full Text Available The internal friction (IF behaviors of dual-phase Ni52Mn32In16 alloy with two-step structural transformation were investigated by dynamic mechanical analyzer. The IF peak for the martensite transformation (MT is an asymmetric shoulder rather than those sharp peaks for other shape memory alloys. The intermartensitic transformation (IMT peak has the maximum IF value. As the heating rate increases, the height of the IMT peak increases and its position is shifted to higher temperatures. In comparison with the IMT peak, the MT peak is independent on the heating rate. The starting temperatures of the IMT peak are strongly dependent on frequency, while the MT peak is weakly dependent. Meanwhile, the heights of both the MT and IMT peak rapidly decrease with increasing the frequency. This work also throws new light on their structural transformation mechanisms.

  7. 4,6-connected fsb topology networks obtained through two-step crystal engineering of decorated trigonal prismatic nodes

    KAUST Repository

    Schoedel, Alexander

    2014-05-07

    A two-step crystal engineering strategy has been utilized to synthesize a new and versatile class of metal-organic materials, the first to exhibit 4,6-connected fsb topology. The new fsb networks are constructed from simple and inexpensive nodes (4-connected Zn(CO2)(py)2 tetrahedra; 6-connected Cr(μ3-O)(RCO2)6 trigonal prisms) and linker ligands (isonicotinate and various dicarboxylates). Further, since interpenetration is precluded, they can exhibit extra-large void volumes. These fsb nets are prototypal for what should ultimately become a large family of related structures given the ready availability of functionalized and/or expanded variants of both linker ligands. The fsb nets described herein therefore represent platforms or blueprints for a new family of ultrahigh surface area porous materials. © 2014 American Chemical Society.

  8. FRAKSINASI ENZIM LIPASE DARI ENDOSPERM KELAPA DENGAN METODE SALTING OUT (Lipase fractionation of Coconut Endosperm by Salting out Method

    Directory of Open Access Journals (Sweden)

    Moh. Su'i

    2014-02-01

    Full Text Available This research learns about fractionation of lipases activity from coconut endosperm by using ammonium sulphate of 0–15%; 15-30 %, 30–45 %, 45–60 %, 60–75 % and 75–90 %. The results showed that the fractions of 0–15% ; 30–45 %, 45–60 % and 60–75 % have lipase activity. Meanwhile, the highest activity was fractions of 60-75%. fractions of 15-30% and 75-90%  have no lipase enzym activity. Molecule weigh of lipase enzyme was 72 kDa. Keywords: Lipases, endosperm, coconut, fractionation, ammonium sulphate   ABSTRAK Penelitian ini mempelajari fraksinasi enzim lipase dari endosperm kelapa menggunakan ammonium sulfat. fraksinasi dilakukan dengan variasi konsentrasi ammonium sulfat 0–15% ; 15-30%; 30–45 %, 45–60 %, 60–75 % dan 75–90 %. Hasil penelitian menunjukkan bahwa enzim lipase terdapat pada fraksi 0–15% ; 30–45 %, 45–60 % dan fraksi 60–75 % dengan aktivitas enzim tertinggi pada fraksi 60-75%. Sedangkan fraksi 15-30% dan 75-90% tidak ada enzim lipase. Berat molekul enzim lipase pada semua fraksi 72 kDa. Kata kunci: Lipase, endosperm, fraksinasi, ammonium sulfat

  9. Studying Hospitalizations and Mortality in the Netherlands: Feasible and Valid Using Two-Step Medical Record Linkage with Nationwide Registers.

    Directory of Open Access Journals (Sweden)

    Elske Sieswerda

    Full Text Available In the Netherlands, the postal code is needed to study hospitalizations of individuals in the nationwide hospitalization register. Studying hospitalizations longitudinally becomes troublesome if individuals change address. We aimed to report on the feasibility and validity of a two-step medical record linkage approach to examine longitudinal trends in hospitalizations and mortality in a study cohort. First, we linked a study cohort of 1564 survivors of childhood cancer with the Municipal Personal Records Database (GBA which has postal code history and mortality data available. Within GBA, we sampled a reference population matched on year of birth, gender and calendar year. Second, we extracted hospitalizations from the Hospital Discharge Register (LMR with a date of discharge during unique follow-up (based on date of birth, gender and postal code in GBA. We calculated the agreement of death and being hospitalized in survivors according to the registers and to available cohort data. We retrieved 1477 (94% survivors from GBA. Median percentages of unique/potential follow-up were 87% (survivors and 83% (reference persons. Characteristics of survivors and reference persons contributing to unique follow-up were comparable. Agreement of hospitalization during unique follow-up was 94% and agreement of death was 98%. In absence of unique identifiers in the Dutch hospitalization register, it is feasible and valid to study hospitalizations and mortality of individuals longitudinally using a two-step medical record linkage approach. Cohort studies in the Netherlands have the opportunity to study mortality and hospitalization rates over time. These outcomes provide insight into the burden of clinical events and healthcare use in studies on patients at risk of long-term morbidities.

  10. In situ synthesis carbonated hydroxyapatite layers on enamel slices with acidic amino acids by a novel two-step method.

    Science.gov (United States)

    Wu, Xiaoguang; Zhao, Xu; Li, Yi; Yang, Tao; Yan, Xiujuan; Wang, Ke

    2015-09-01

    In situ fabrication of carbonated hydroxyapatite (CHA) remineralization layer on an enamel slice was completed in a novel, biomimetic two-step method. First, a CaCO3 layer was synthesized on the surface of demineralized enamel using an acidic amino acid (aspartic acid or glutamate acid) as a soft template. Second, at the same concentration of the acidic amino acid, rod-like carbonated hydroxyapatite was produced with the CaCO3 layer as a sacrificial template and a reactant. The morphology, crystallinity and other physicochemical properties of the crystals were characterized using field emission scanning electron microscopy (FESEM), Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD) and energy-dispersive X-ray analysis (EDAX), respectively. Acidic amino acid could promote the uniform deposition of hydroxyapatite with rod-like crystals via absorption of phosphate and carbonate ions from the reaction solution. Moreover, compared with hydroxyapatite crystals coated on the enamel when synthesized by a one-step method, the CaCO3 coating that was synthesized in the first step acted as an active bridge layer and sacrificial template. It played a vital role in orienting the artificial coating layer through the template effect. The results show that the rod-like carbonated hydroxyapatite crystals grow into bundles, which are similar in size and appearance to prisms in human enamel, when using the two-step method with either aspartic acid or acidic glutamate (20.00 mmol/L). Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Semi-Automated Hydrophobic Interaction Chromatography Column Scouting Used in the Two-Step Purification of Recombinant Green Fluorescent Protein

    Science.gov (United States)

    Murphy, Patrick J. M.

    2014-01-01

    Background Hydrophobic interaction chromatography (HIC) most commonly requires experimental determination (i.e., scouting) in order to select an optimal chromatographic medium for purifying a given target protein. Neither a two-step purification of untagged green fluorescent protein (GFP) from crude bacterial lysate using sequential HIC and size exclusion chromatography (SEC), nor HIC column scouting elution profiles of GFP, have been previously reported. Methods and Results Bacterial lysate expressing recombinant GFP was sequentially adsorbed to commercially available HIC columns containing butyl, octyl, and phenyl-based HIC ligands coupled to matrices of varying bead size. The lysate was fractionated using a linear ammonium phosphate salt gradient at constant pH. Collected HIC eluate fractions containing retained GFP were then pooled and further purified using high-resolution preparative SEC. Significant differences in presumptive GFP elution profiles were observed using in-line absorption spectrophotometry (A395) and post-run fluorimetry. SDS-PAGE and western blot demonstrated that fluorometric detection was the more accurate indicator of GFP elution in both HIC and SEC purification steps. Comparison of composite HIC column scouting data indicated that a phenyl ligand coupled to a 34 µm matrix produced the highest degree of target protein capture and separation. Conclusions Conducting two-step protein purification using the preferred HIC medium followed by SEC resulted in a final, concentrated product with >98% protein purity. In-line absorbance spectrophotometry was not as precise of an indicator of GFP elution as post-run fluorimetry. These findings demonstrate the importance of utilizing a combination of detection methods when evaluating purification strategies. GFP is a well-characterized model protein, used heavily in educational settings and by researchers with limited protein purification experience, and the data and strategies presented here may aid in

  12. "Two-step" technique with OsiriXTM to evaluate feasibility of C2 pedicle for surgical fixation

    Directory of Open Access Journals (Sweden)

    Luis Miguel Sousa Marques

    2016-01-01

    Full Text Available Background: Surgical treatment of craniovertebral junction pathology has evolved considerably in recent decades with the implementation of short atlanto-axial fixation techniques, notwhithstanding increasing neurovascular risks. Also, there is strong evidence that fixation of C2 anatomical pedicle has the best biomechanical profile of the entire cervical spine. However, it is often difficult and misleading, to evaluate anatomical bony and vascular anomalies using the three orthogonal planes (axial, coronal, and sagittal of CT. Objectives: The authors describe an innovative and simple technique to evaluate the feasibility of C2 pedicle for surgical screw fixation using preoperative planning with the free DICOM (Digital Imaging and Communications in Medicine software OsiriX TM . Materials and Methods: The authors report the applicatin of this novel technique in 5 cases (3 traumatic, 1 Os Odontoideum, and 1 complex congenital malformation collected from our general case series of the Department in the last 5 years. Results: In this "proof of concept" study, the pre-operative analysis with the "two-step" tecnique was detrimental for choosing the surgical tecnique. Detailed post-operative analysis confirmed correct position of C2 screws without cortical breach. There were no complications or mortality reported. Conclusion: This "two-step" technique is an easy and reliable way to determine the feasibility of C2 pedicle for surgical fixation. The detailed tridimensional radiological preoperative evaluation of craniovertebral junction anatomy is critical to the sucess and safety of this surgeries, and can avoid, to certain degree, expensive intra-operative tridimensional imaging facilities.

  13. A new continuous two-step molecular precursor route to rare-earth oxysulfides Ln2O2S

    International Nuclear Information System (INIS)

    De Crom, N.; Devillers, M.

    2012-01-01

    A continuous two-step molecular precursor pathway is designed for the preparation of rare-earth oxysulfides Ln 2 O 2 S (Ln=Y, La, Pr, Nd, Sm–Lu). This new route involves a first oxidation step leading to the rare-earth oxysulfate Ln 2 O 2 SO 4 which is subsequently reduced to the rare-earth oxysulfide Ln 2 O 2 S by switching to a H 2 –Ar atmosphere. The whole process occurs at a temperature significantly lower than usual solid state synthesis (T≤650 °C) and avoids the use of dangerous sulfur-based gases, providing a convenient route to the synthesis of the entire series of Ln 2 O 2 S. The molecular precursors consist in heteroleptic dithiocarbamate complexes [Ln(Et 2 dtc) 3 (phen)] and [Ln(Et 2 dtc) 3 (bipy)] (Et 2 dtc=N,N-diethyldithiocarbamate; phen=1,10-phenanthroline; bipy=2,2′-bipyridine) and were synthesized by a new high yield and high purity synthesis route. The nature of the molecular precursor determines the minimum synthesis temperature and influences therefore the purity of the final Ln 2 O 2 S crystalline phase. - Graphical abstract: A continuous two-step molecular precursor pathway was designed for the preparation of rare-earth oxysulfides Ln 2 O 2 S (Ln=Y, La, Pr, Nd, Sm–Lu), starting from heteroleptic dithiocarbamate complexes. The influence of the nature of the molecular precursor on the minimum synthesis temperature and on the purity of the final Ln 2 O 2 S crystalline phase is discussed. Highlights: ► A new high yield and high purity synthesis route of rare earth dithiocarbamates is described. ► These compounds are used as precursors in a continuous process leading to rare-earth oxysulfides. ► The oxysulfides are obtained under much more moderate conditions than previously described.

  14. A dynamic dual role of IL-2 signaling in the two-step differentiation process of adaptive regulatory T cells.

    Science.gov (United States)

    Guo, Zhiyong; Khattar, Mithun; Schroder, Paul M; Miyahara, Yoshihiro; Wang, Guohua; He, Xiaoshung; Chen, Wenhao; Stepkowski, Stanislaw M

    2013-04-01

    The molecular mechanism of the extrathymic generation of adaptive, or inducible, CD4(+)Foxp3(+) regulatory T cells (iTregs) remains incompletely defined. We show that exposure of splenic CD4(+)CD25(+)Foxp3(-) cells to IL-2, but not other common γ-chain cytokines, resulted in Stat5 phosphorylation and induced Foxp3 expression in ∼10% of the cells. Thus, IL-2/Stat5 signaling may be critical for Foxp3 induction in peripheral CD4(+)CD25(+)Foxp3(-) iTreg precursors. In this study, to further define the role of IL-2 in the formation of iTreg precursors as well as their subsequent Foxp3 expression, we designed a two-step iTreg differentiation model. During the initial "conditioning" step, CD4(+)CD25(-)Foxp3(-) naive T cells were activated by TCR stimulation. Inhibition of IL-2 signaling via Jak3-Stat5 was required during this step to generate CD4(+)CD25(+)Foxp3(-) cells containing iTreg precursors. During the subsequent Foxp3-induction step driven by cytokines, IL-2 was the most potent cytokine to induce Foxp3 expression in these iTreg precursors. This two-step method generated a large number of iTregs with relatively stable expression of Foxp3, which were able to prevent CD4(+)CD45RB(high) cell-mediated colitis in Rag1(-/-) mice. In consideration of this information, whereas initial inhibition of IL-2 signaling upon T cell priming generates iTreg precursors, subsequent activation of IL-2 signaling in these precursors induces the expression of Foxp3. These findings advance the understanding of iTreg differentiation and may facilitate the therapeutic use of iTregs in immune disorders.

  15. Clinical feasibility of two-step streptavidin/111In-biotin scintigraphy in patients with suspected vertebral osteomyelitis

    International Nuclear Information System (INIS)

    Lazzeri, Elena; Erba, Paola A.; Volterrani, Duccio; Bottoni, Antonio; Mariani, Giuliano; Pauwels, Ernest K.J.; Manca, Mario; Bodei, Lisa; Trippi, Donatella; Cristofani, Renza; Consoli, Vincenzo; Palestro, Christopher J.

    2004-01-01

    Streptavidin accumulates at sites of inflammation and infection as a result of increased capillary permeability. In addition to being utilised by bacteria for their own growth, biotin forms a stable, high-affinity non-covalent complex with avidin. The objective of this investigation was to determine the diagnostic performance of two-step streptavidin/ 111 In-biotin imaging for evaluating patients with suspected vertebral osteomyelitis. We evaluated 55 consecutive patients with suspected vertebral osteomyelitis (34 women and 21 men aged 27-86 years), within 2 weeks after the onset of clinical symptoms. Thirty-two of the patients underwent magnetic resonance imaging (MRI) and 24, computed tomography (CT). DTPA-conjugated biotin was radiolabelled by incubating 500 μg of DTPA-biotin with 111 MBq of 111 In-chloride. Two-step scintigraphy was performed by first infusing 3 mg streptavidin intravenously, followed 4 h later by 111 In-biotin. Imaging was begun 60 min later. Streptavidin/ 111 In-biotin scintigraphy was positive in 32/34 patients with spinal infection (94.12% sensitivity). The study was negative in 19/21 patients without infection (95.24% specificity). The corresponding results for MRI and CT were 54.17% and 35.29% (sensitivity), and 75% and 57.14% (specificity), respectively. All statistical parameters of diagnostic performance (Youden's J index, kappa measure of agreement with correct classification, accuracy, sensitivity, specificity, positive likelihood and negative likelihood) were clearly better for streptavidin/ 111 In-biotin scintigraphy than for either MRI or CT. Streptavidin/ 111 In-biotin scintigraphy is highly sensitive and specific for detecting vertebral osteomyelitis in the first 2 weeks after the onset of clinical symptoms, and is potentially very useful for guiding clinical decisions on instituting appropriate therapy. (orig.)

  16. Microleakage assessment of one- and two-step self-etch adhesive systems with ‎the low shrinkage composites

    Directory of Open Access Journals (Sweden)

    Razieh Hoseinifar

    2015-07-01

    Full Text Available BACKGROUND AND AIM: Different studies evaluating one-step self-etch (SE adhesive systems show contradictory findings, so the aim of this study was to compare the microleakage of one-step SE adhesive systems and CLEARFIL SE BOND (that serves as the “gold-standard” SE adhesive with low shrinkage composites. METHODS: In this in vitro study, Class V cavities with the occlusal margin in enamel and cervical margin in cementum were prepared on the buccal and lingual surfaces of 36 human premolars and molars (72 cavities. The enamel surfaces of the cavities were etched with 37% phosphoric acid and then the specimens were divided into six groups of 6 (12 cavities and the cavities were restored according bellow: Group 1 (Kalore-GC + G-Bond, Group 2 (Grandio + Futurabond NR, Group 3 (Aelite LS Posterior + All Bond SE, Group 4 (Kalore-GC + CLEARFIL SE BOND, Group 5 (Grandio + CLEARFIL SE BOND, and Group 6 (Aelite LS Posterior + CLEARFIL SE BOND. All the specimens were thermocycled for 2000 cycles (5-55 °C and then placed in 0.5% basic fuchsine dye for 24 hours at 37 °C and finally sectioned and observed under the stereomicroscope. Data were analyzed using Kruskal-Wallis, Mann-Whitney, and Wilcoxon tests at a P 0.050. There were no significant differences in microleakage among two-step and one-step SE adhesive systems on both the occlusal and gingival margins. CONCLUSION: According to this study, two-step SE adhesive system (CLEARFIL SE BOND did not provide better marginal seal than the one-step SE adhesive systems.

  17. Two step synthesis, electromagnetic and microwave absorbing properties of FeCo@C core–shell nanostructure

    Energy Technology Data Exchange (ETDEWEB)

    Afghahi, S.S.S., E-mail: salmanafghahi@gmail.com [Materials Science and Engineering Imam Hossein University, Department of Engineering, Babaei Highway, P.O. Box: 15816-18711, Tehran (Iran, Islamic Republic of); Shokuhfar, A. [Advanced Materials and Nanotechnology Research Laboratory, Department of Materials Science and Engineering K.N. Toosi University of Technology, P.O. Box: 19395-1999, Tehran (Iran, Islamic Republic of)

    2014-12-15

    In this research synthesis of FeCo@C core–shell nanoparticles was done using a novel two step process including the microemulsion technique and alcohol catalytic chemical vapor deposition. X-ray diffraction, transmission electron microscopy, electron beam diffraction and energy dispersive spectroscopy confirm the formation of FeCo@graphite core–shell nanostructure. Compared with FeCo nanoparticles with an oxide shell, the graphite shell restricts the growth of the FeCo nanoparticles, leading to lower saturation magnetization and higher natural-resonance frequency. The electromagnetic characteristics including permittivity, permeability and loss tangents of FeCo nanoparticles/nanoencapsulates were determined in the frequency range of 2–18 GHz. Results show that the graphite coating dramatically improves electromagnetic wave absorption of FeCo nanoparticles due to several dielectric/magnetic loss mechanisms. The main mechanism enhancing the dielectric loss tangent is Deby's dual relaxation phenomenon and for magnetic loss is the ferromagnetic resonance. The maximum reflection loss of −40 dB at 2.5 mm thickness and the maximum effective absorption bandwidth (RL<−20 dB) of 5.6 GHz at 3 mm thickness were obtained for FeCo nanoencapsulates. - Highlights: • FeCo@C core–shell nanoparticles were synthesized using a novel two step process. • Graphite coating dramatically improves the EM wave absorption of FeCo NPs. • FeCo@C nanoparticles represent high values of both magnetic and dielectric losses. • Maximum RL of −40 dB was obtained at 2.5 mm thickness. • Maximum effective bandwidth (RL<−20 dB) of 5.6 GHz was obtained at 3 mm thickness.

  18. Relation between Hydrogen Evolution and Hydrodesulfurization Catalysis

    DEFF Research Database (Denmark)

    Šaric, Manuel; Moses, Poul Georg; Rossmeisl, Jan

    2016-01-01

    A relation between hydrogen evolution and hydrodesulfurization catalysis was found by density functional theory calculations. The hydrogen evolution reaction and the hydrogenation reaction in hydrodesulfurization share hydrogen as a surface intermediate and, thus, have a common elementary step...

  19. Special section on Nano-Catalysis

    CSIR Research Space (South Africa)

    Makgwane, PR

    2013-01-01

    Full Text Available to achieve sustainable and green catalytic processes. The special issue contains 40 peer reviewed scientific papers that include four comprehensive review articles contributions from the invited experts in the respective catalysis fields....

  20. Current trends of surface science and catalysis

    CERN Document Server

    Park, Jeong Young

    2014-01-01

    Including detail on applying surface science in renewable energy conversion, this book covers the latest results on model catalysts including single crystals, bridging "materials and pressure gaps", and hot electron flows in heterogeneous catalysis.

  1. Faraday Discussions meeting Catalysis for Fuels.

    Science.gov (United States)

    Fischer, Nico; Kondrat, Simon A; Shozi, Mzamo

    2017-05-02

    Welcome to Africa was the motto when after more than 100 years the flag ship conference series of the Royal Society of Chemistry, the Faraday Discussions was hosted for the first time on the African Continent. Under the fitting topic 'Catalysis for Fuels' over 120 delegates followed the invitation by the conference chair Prof. Graham Hutchings FRS (Cardiff Catalysis Institute), his organizing committee and the co-organizing DST-NRF Centre of Excellence in Catalysis c*change (). In the presentations of 21 invited speakers and 59 posters, cutting edge research in the field of catalysis for fuels, designing new catalysts for synthetic fuels, hydrocarbon conversion in the production of synthetic fuels and novel photocatalysis was presented over the two-day meeting. The scene was set by the opening lecture of Prof. Enrique Iglesias (UC Berkeley) and wrapped-up with the concluding remarks by Philip Gibson (SASOL).

  2. Differential effect of combined lipase deficiency (cld/cld) on human hepatic lipase and lipoprotein lipase secretion.

    Science.gov (United States)

    Boedeker, J C; Doolittle, M H; White, A L

    2001-11-01

    Combined lipase deficiency (cld) is a recessively inherited disorder in mice associated with a deficiency of LPL and hepatic lipase (HL) activity. LPL is synthesized in cld tissues but is retained in the endoplasmic reticulum (ER), whereas mouse HL (mHL) is secreted but inactive. In this study we investigated the effect of cld on the secretion of human HL (hHL) protein mass and activity. Differentiated liver cell lines were derived from cld mice and their normal heterozygous (het) littermates by transformation of hepatocytes with SV40 large T antigen. After transient transfection with lipase expression constructs, secretion of hLPL activity from cld cells was only 12% of that from het cells. In contrast, the rate of secretion of hHL activity and protein mass per unit of expressed hHL mRNA was identical for the two cell lines. An intermediate effect was observed for mHL, with a 46% reduction in secretion of activity from cld cells. The ER glucosidase inhibitor, castanospermine, decreased secretion of both hLPL and hHL from het cells by approximately 70%, but by only approximately 45% from cld cells. This is consistent with data suggesting that cld may result from a reduced concentration of the ER chaperone calnexin. In conclusion, our results demonstrate a differential effect of cld on hLPL, mHL, and hHL secretion, suggesting differential requirements for activation and exit of the enzymes from the ER.

  3. Gastric lipase: localization of the enzyme in the stomach

    International Nuclear Information System (INIS)

    DeNigris, S.J.; Hamosh, M.; Hamosh, P.; Kasbekar, D.K.

    1986-01-01

    Isolated gastric glands prepared from human and rabbit stomach secrete lipase in response to secretagogues. They have investigated the localization of this enzyme in three species (rabbit, baboon, guinea pig). Gastric mucosa was sampled from the cardia (C), fundus-smooth (FS), fundus-ruggae (FR) and the antral area (A). Lipase activity was measured in mucosal homogenates using 3 H-triolein as substrate and is expressed in units (U) = nmols free fatty acid released/min/mg wet weight. The localization of lipase is compared with that of pepsin (measured by hydrolysis of 2% hemoglobin at pH 1.8 and expressed in I.U.). Lipase is localized in a well defined area in the rabbit and is diffusely distributed in both guinea pig and baboon. The distribution of lipase and pepsin containing cells differs in all three species. The cellular origin of gastric lipase remains to be determined

  4. Engineering Lipases: walking the fine line between activity and stability

    Science.gov (United States)

    Dasetty, Siva; Blenner, Mark A.; Sarupria, Sapna

    2017-11-01

    Lipases are enzymes that hydrolyze lipids and have several industrial applications. There is a tremendous effort in engineering the activity, specificity and stability of lipases to render them functional in a variety of environmental conditions. In this review, we discuss the recent experimental and simulation studies focused on engineering lipases. Experimentally, mutagenesis studies have demonstrated that the activity, stability, and specificity of lipases can be modulated by mutations. It has been particularly challenging however, to elucidate the underlying mechanisms through which these mutations affect the lipase properties. We summarize results from experiments and molecular simulations highlighting the emerging picture to this end. We end the review with suggestions for future research which underscores the delicate balance of various facets in the lipase that affect their activity and stability necessitating the consideration of the enzyme as a network of interactions.

  5. Advancing Sustainable Catalysis with Magnetite Surface ...

    Science.gov (United States)

    This article surveys the recent developments in the synthesis, surface modification, and synthetic applications of magnetitenanoparticles. The emergence of iron(II,III) oxide (triiron tetraoxide or magnetite; Fe3O4, or FeO•Fe2O3) nanoparticles as a sustainable support in heterogeneous catalysis is highlighted. Use of an oxide of earth-abundant iron for various applications in catalysis and environmental remediation.

  6. New developments in oxidation catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Rosowski, F. [BASF SE, Ludwigshafen (Germany)

    2011-07-01

    The impact of heterogeneous catalysis on the economy can be depicted by the global revenue of the chemical industry in 2006, which accounted for 2200 billion Euros with a share of all chemical products produced applying heterogeneous catalysis of about two thirds. [1] The range of products is enormous and they contribute greatly to the quality of our lifes. The advancement in the development of basic and intermediate chemical products is crucially dependent on either the further development of existing catalyst systems or the development of new catalysts and key to success for the chemical industry. Within the context of oxidation catalysis, the following driving forces are guiding research activities: There is a continuous desire to increase the selectivity of a given process in response to both economic as well as ecological needs and taking advantage of higher efficiencies in terms of cost savings and a better utilization of raw materials. A second motivation focuses on raw material change to all abundant and competitive feedstocks requiring both new developments in catalyst design as well as process technology. A more recent motivation refers to the use of metal oxide redox systems which are key to success for the development of novel technologies allowing for the separation of carbon dioxide and the use of carbon dioxide as a feedstock molecule as well as storing renewable energy in a chemical. To date, general ab initio approaches are known for the design of novel catalytic materials only for a few chemical reactions, whereas most industrial catalytic processes have been developed by empirical methods. [2] The development of catalytic materials are either based on the targeted synthesis of catalytic lead structures as well as high throughput methods that allow for the screening of a large range of parameters. [3 - 5] The successful development of catalysts together with reactor technology has led to both significant savings in raw materials and emissions. The

  7. Immobilization of Isolated Lipase From Moldy Copra (Aspergillus Oryzae)

    OpenAIRE

    Dali, Seniwati; Patong, A. B. D. Rauf; Jalaluddin, M. Noor; Pirman; Hamzah, Baharuddin

    2011-01-01

    Enzyme immobilization is a recovery technique that has been studied in several years, using support as a media to help enzyme dissolutions to the reaction substrate. Immobilization method used in this study was adsorption method, using specific lipase from Aspergillus oryzae. Lipase was partially purified from the culture supernatant of Aspergillus oryzae. Enzyme was immobilized by adsorbed on silica gel. Studies on free and immobilized lipase systems for determination of optimum pH, optimum ...

  8. Biosensor Applications of MAPLE Deposited Lipase

    Directory of Open Access Journals (Sweden)

    Valeria Califano

    2014-10-01

    Full Text Available Matrix Assisted Pulsed Laser Evaporation (MAPLE is a thin film deposition technique derived from Pulsed Laser Deposition (PLD for deposition of delicate (polymers, complex biological molecules, etc. materials in undamaged form. The main difference of MAPLE technique with respect to PLD is the target: it is a frozen solution or suspension of the (guest molecules to be deposited in a volatile substance (matrix. Since laser beam energy is mainly absorbed by the matrix, damages to the delicate guest molecules are avoided, or at least reduced. Lipase, an enzyme catalyzing reactions borne by triglycerides, has been used in biosensors for detection of β-hydroxyacid esters and triglycerides in blood serum. Enzymes immobilization on a substrate is therefore required. In this paper we show that it is possible, using MAPLE technique, to deposit lipase on a substrate, as shown by AFM observation, preserving its conformational structure, as shown by FTIR analysis.

  9. Immobilised lipases in the cosmetics industry.

    Science.gov (United States)

    Ansorge-Schumacher, Marion B; Thum, Oliver

    2013-08-07

    Commercial products for personal care, generally perceived as cosmetics, have an important impact on everyday life worldwide. Accordingly, the market for both consumer products and specialty chemicals comprising their ingredients is considerable. Lipases have started to play a minor role as active ingredients in so-called 'functional cosmetics' as well as a major role as catalysts for the industrial production of various specialty esters, aroma compounds and active agents. Interestingly, both applications almost always require preparation by appropriate immobilisation techniques. In addition, for catalytic use special reactor concepts often have to be employed due to the mostly limited stability of these preparations. Nevertheless, these processes show distinct advantages based on process simplification, product quality and environmental footprint and are therefore apt to more and more replace traditional chemical processes. Here, for the first time a review on the various aspects of using immobilised lipases in the cosmetics industry is given.

  10. Lipoprotein lipase deficiency with visceral xanthomas

    Energy Technology Data Exchange (ETDEWEB)

    Servaes, Sabah; Bellah, Richard [Department of Radiology, Philadelphia, PA (United States); Verma, Ritu [Department of Gastroenterology, Philadelphia, PA (United States); Pawel, Bruce [Department of Pathology, Philadelphia, PA (United States)

    2010-08-15

    Lipoprotein lipase deficiency (LLD) is a rare metabolic disorder that typically presents with skin xanthomas and pancreatitis in childhood. We report a case of LLD in an infant who presented with jaundice caused by a pancreatic head mass. Abdominal imaging also incidentally revealed hyperechoic renal masses caused by renal xanthomas. This appearance of the multiple abdominal masses makes this a unique infantile presentation of LLD. (orig.)

  11. Lipoprotein lipase: genetics, lipid uptake, and regulation.

    Science.gov (United States)

    Merkel, Martin; Eckel, Robert H; Goldberg, Ira J

    2002-12-01

    Lipoprotein lipase (LPL) regulates the plasma levels of triglyceride and HDL. Three aspects are reviewed. 1) Clinical implications of human LPL gene variations: common mutations and their effects on plasma lipids and coronary heart disease are discussed. 2) LPL actions in the nervous system, liver, and heart: the discussion focuses on LPL and tissue lipid uptake. 3) LPL gene regulation: the LPL promoter and its regulatory elements are described.

  12. Efficient utilization of xylanase and lipase producing thermophilic ...

    African Journals Online (AJOL)

    Efficient utilization of xylanase and lipase producing thermophilic marine actinomycetes ( Streptomyces albus and Streptomyces hygroscopicus ) in the production of ecofriendly alternative energy from waste.

  13. Applications of immobilized Thermomyces lanuginosa lipase in interesterification

    DEFF Research Database (Denmark)

    Yang, Tiankui; Fruekilde, Maj-Britt; Xu, Xuebing

    2003-01-01

    (RSM). Thermomyces lanuginosa lipase had an activity similar to that of immobilized Rhizomucor miehei lipase (Lipozyme RM IM) in the glycerolysis of sunflower oil, but the former had higher activity at a low reaction temperature (5degreesC). Thermomyces lanuginosa lipase was found to have much lower...... catalytic activity than Lipozyme RM IM in the acidolysis of sunflower oil with caprylic acid. However, the activity of T. lanuginosa lipase was only slightly lower than that of Lipozyme RM IM in the ester-ester exchange between tripalmitin (PPP) and the ethyl esters of EPA and DHA (EE). For this reason...

  14. Seed lipases: sources, applications and properties - a review

    Directory of Open Access Journals (Sweden)

    M. Barros

    2010-03-01

    Full Text Available This paper provides an overview regarding the main aspects of seed lipases, such as the reactions catalyzed, physiological functions, specificities, sources and applications. Lipases are ubiquitous in nature and are produced by several plants, animals and microorganisms. These enzymes exhibit several very interesting features, such as low cost and easy purification, which make their commercial exploitation as industrial enzymes a potentially attractive alternative. The applications of lipases in food, detergents, oils and fats, medicines and fine chemistry, effluent treatment, biodiesel production and in the cellulose pulp industry, as well as the main sources of oilseed and cereal seed lipases, are reviewed.

  15. Endothelial lipase is a major determinant of HDL level

    Energy Technology Data Exchange (ETDEWEB)

    Ishida, Tatsuro; Choi, Sungshin; Kundu, Ramendra K.; Hirata, Ken-Ichi; Rubin, Edward M.; Cooper, Allen D.; Quertermous, Thomas

    2003-01-30

    For the past three decades, epidemiologic studies have consistently demonstrated an inverse relationship between plasma HDL cholesterol (HDL-C) concentrations and coronary heart disease (CHD). Population-based studies have provided compelling evidence that low HDL-C levels are a risk factor for CHD, and several clinical interventions that increased plasma levels of HDL-C were associated with a reduction in CHD risk. These findings have stimulated extensive investigation into the determinants of plasma HDL-C levels. Turnover studies using radiolabeled apolipoprotein A-I, the major protein component of HDL, suggest that plasma HDL-C concentrations are highly correlated with the rate of clearance of apolipoprotein AI. However, the metabolic mechanisms by which HDL are catabolized have not been fully defined. Previous studies in humans with genetic deficiency of cholesteryl ester transfer protein, and in mice lacking the scavenger receptor BI (SR-BI), have demonstrated that these proteins participate in the removal of cholesterol from HDL, while observations in individuals with mutations in hepatic lipase indicate that this enzyme hydrolyzes HDL triglycerides. In this issue of the JCI, reports from laboratories of Tom Quertermous and Dan Rader now indicate that endothelial lipase (LIPG), a newly identified member of the lipase family, catalyzes the hydrolysis of HDL phospholipids and facilitates the clearance of HDL from the circulation. Endothelial lipase was initially cloned by both of these laboratories using entirely different strategies. Quertermous and his colleagues identified endothelial lipase as a transcript that was upregulated in cultured human umbilical vein endothelial cells undergoing tube formation, whereas the Rader group cloned endothelial lipase as a transcript that was upregulated in the human macrophage-like cell line THP-1 exposed to oxidized LDL. Database searches revealed that endothelial lipase shows strong sequence similarity to lipoprotein

  16. Study of enzymatic reactors with microencapsulated lipase. Doctoral thesis. Estudo de reactores enzimaticos com lipase microencapsulada

    Energy Technology Data Exchange (ETDEWEB)

    de Franca Teixeira dos Prazeres, D.M.

    1992-10-01

    The work reports the development of a membrane reactor for the hydrolysis of triglycerides catalyzed by lipase B from Chromobacterium viscosum in AOT/isooctane reversed miceller system. In a preliminary phase the potential of the organic system was evaluated with comparative studies on the activity and stability of lipase B in aqueous media (emulsion) and in the alternative miceller media. A tubular ceramic membrane reactor with recirculation was selected for the olive oil hydrolysis in a reversed miceller system. The influence of the hydration degree, recirculation rate, AOT, olive oil and lipase concentration in the operation of the reactor were investigated in a batch mode. The hydration degree was identified as a critical parameter due to its influence in the separation process and in the kinetics of the reaction.

  17. Biodiesel production by transesterification using immobilized lipase.

    Science.gov (United States)

    Narwal, Sunil Kumar; Gupta, Reena

    2013-04-01

    Biodiesel can be produced by transesterification of vegetable or waste oil catalysed by lipases. Biodiesel is an alternative energy source to conventional fuel. It combines environmental friendliness with biodegradability, low toxicity and renewability. Biodiesel transesterification reactions can be broadly classified into two categories: chemical and enzymatic. The production of biodiesel using the enzymatic route eliminates the reactions catalysed under acid or alkali conditions by yielding product of very high purity. The modification of lipases can improve their stability, activity and tolerance to alcohol. The cost of lipases and the relatively slower reaction rate remain the major obstacles for enzymatic production of biodiesel. However, this problem can be solved by immobilizing the enzyme on a suitable matrix or support, which increases the chances of re-usability. The main factors affecting biodiesel production are composition of fatty acids, catalyst, solvents, molar ratio of alcohol and oil, temperature, water content, type of alcohol and reactor configuration. Optimization of these parameters is necessary to reduce the cost of biodiesel production.

  18. ISOTOPE METHODS IN HOMOGENEOUS CATALYSIS.

    Energy Technology Data Exchange (ETDEWEB)

    BULLOCK,R.M.; BENDER,B.R.

    2000-12-01

    The use of isotope labels has had a fundamentally important role in the determination of mechanisms of homogeneously catalyzed reactions. Mechanistic data is valuable since it can assist in the design and rational improvement of homogeneous catalysts. There are several ways to use isotopes in mechanistic chemistry. Isotopes can be introduced into controlled experiments and followed where they go or don't go; in this way, Libby, Calvin, Taube and others used isotopes to elucidate mechanistic pathways for very different, yet important chemistries. Another important isotope method is the study of kinetic isotope effects (KIEs) and equilibrium isotope effect (EIEs). Here the mere observation of where a label winds up is no longer enough - what matters is how much slower (or faster) a labeled molecule reacts than the unlabeled material. The most careti studies essentially involve the measurement of isotope fractionation between a reference ground state and the transition state. Thus kinetic isotope effects provide unique data unavailable from other methods, since information about the transition state of a reaction is obtained. Because getting an experimental glimpse of transition states is really tantamount to understanding catalysis, kinetic isotope effects are very powerful.

  19. Lipase immobilization and production of fatty acid methyl esters from canola oil using immobilized lipase

    International Nuclear Information System (INIS)

    Yuecel, Yasin; Demir, Cevdet; Dizge, Nadir; Keskinler, Buelent

    2011-01-01

    Lipase enzyme from Aspergillus oryzae (EC 3.1.1.3) was immobilized onto a micro porous polymeric matrix which contains aldehyde functional groups and methyl esters of long chain fatty acids (biodiesel) were synthesized by transesterification of crude canola oil using immobilized lipase. Micro porous polymeric matrix was synthesized from styrene-divinylbenzene (STY-DVB) copolymers by using high internal phase emulsion technique and two different lipases, Lipozyme TL-100L ® and Novozym 388 ® , were used for immobilization by both physical adsorption and covalent attachment. Biodiesel production was carried out with semi-continuous operation. Methanol was added into the reactor by three successive additions of 1:4 M equivalent of methanol to avoid enzyme inhibition. The transesterification reaction conditions were as follows: oil/alcohol molar ratio 1:4; temperature 40 o C and total reaction time 6 h. Lipozyme TL-100L ® lipase provided the highest yield of fatty acid methyl esters as 92%. Operational stability was determined with immobilized lipase and it indicated that a small enzyme deactivation occurred after used repeatedly for 10 consecutive batches with each of 24 h. Since the process is yet effective and enzyme does not leak out from the polymer, the method can be proposed for industrial applications. -- Research highlights: → Lipozyme TL-100L and Novozym 388 were immobilized onto micro porous polymeric matrix by both physical adsorption and covalent linking. → Immobilized enzymes were used for synthesis of fatty acid methyl esters by transesterification of canola oil and methanol using semi-continuous operation system. → According to chromatographic analysis, Lipase Lipozyme TL-100L resulted in the highest yield of methyl ester as 92%.

  20. Lipase production by recombinant strains of Aspergillus niger expressing a lipase-encoding gene from Thermomyces lanuginosus

    DEFF Research Database (Denmark)

    Prathumpai, Wai; Flitter, S.J.; Mcintyre, Mhairi

    2004-01-01

    Two recombinant strains of Aspergillus niger (NW 297-14 and NW297-24) producing a heterologous lipase from Thermomyces lanuginosus were constructed. The heterologous lipase was expressed using the TAKA amylase promoter from Aspergillus oryzae. The production kinetics of the two strains on different...... shows that it is possible to obtain high productivities of heterologous fungal enzymes in A. niger. However, SDS-PAGE analysis showed that most of the produced lipase was bound to the cell wall....

  1. Two-Step Resonance-Enhanced Desorption Laser Mass Spectrometry for In Situ Analysis of Organic-Rich Environments

    Science.gov (United States)

    Getty, S. A.; Grubisic, A.; Uckert, K.; Li, X.; Cornish, T.; Cook, J. E.; Brinckerhoff, W. B.

    2016-01-01

    A wide diversity of planetary surfaces in the solar system represent high priority targets for in situ compositional and contextual analysis as part of future missions. The planned mission portfolio will inform our knowledge of the chemistry at play on Mars, icy moons, comets, and primitive asteroids, which can lead to advances in our understanding of the interplay between inorganic and organic building blocks that led to the evolution of habitable environments on Earth and beyond. In many of these environments, the presence of water or aqueously altered mineralogy is an important indicator of habitable environments that are present or may have been present in the past. As a result, the search for complex organic chemistry that may imply the presence of a feedstock, if not an inventory of biosignatures, is naturally aligned with targeted analyses of water-rich surface materials. Here we describe the two-step laser mass spectrometry (L2MS) analytical technique that has seen broad application in the study of organics in meteoritic samples, now demonstrated to be compatible with an in situ investigation with technique improvements to target high priority planetary environments as part of a future scientific payload. An ultraviolet (UV) pulsed laser is used in previous and current embodiments of laser desorption/ionization mass spectrometry (LDMS) to produce ionized species traceable to the mineral and organic composition of a planetary surface sample. L2MS, an advanced technique in laser mass spectrometry, is selective to the aromatic organic fraction of a complex sample, which can provide additional sensitivity and confidence in the detection of specific compound structures. Use of a compact two-step laser mass spectrometer prototype has been previously reported to provide specificity to key aromatic species, such as PAHs, nucleobases, and certain amino acids. Recent improvements in this technique have focused on the interaction between the mineral matrix and the

  2. The formation of FHA coating on biodegradable Mg-Zn-Zr alloy using a two-step chemical treatment method

    International Nuclear Information System (INIS)

    Jiang, S.T.; Zhang, J.; Shun, S.Z.; Chen, M.F.

    2016-01-01

    Highlights: • Use a two-step chemical treatment method for formation of FHA coating on biodegradable Mg-Zn-Zr alloy;. • We reported the formation mechanism of FHA coating on Mg-Zn-Zr alloy and achieved optimum properties;. • The MgF_2 coating and FHA coating provide effective protection for the Mg alloy substrate and the FHA coating showed better corrosion resistance. - Abstract: To improve the corrosion resistance of the biomedical magnesium alloy, a two-step chemical treatment method has been employed to prepare an FHA coating on the alloy surface. Prior to forming an FHA layer, the samples of Mg-3 wt% Zn-0.5 wt% Zr alloy were soaked in HF with concentration of 20% (v/v) at 37 °C temperature for 2 h, and were then placed into an aqueous solution with 0.1 mol/L Ca(NO_3).4H_2O and 0.06 mol/L NH_4H_2PO_4 at 90 °C to prepare the Ca-P coating. The concentrations of Mg"2"+, F"− ions, and pH variation with immersing time in the solution were investigated to explore the growth mechanism of FHA. The surface morphologies and compositions of the coatings were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. The results showed that the alloy surface treated with acid formed a layer of MgF_2 nanoparticles with a thickness of 0.7 μm. The corrosion resistance of coatings in SBF solution was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The results showed that the substrate with FHA coating had good corrosion resistance. After immersing into the calcium phosphate solution, some small spherical particles were first formed on the surface; these then cover the surface completely after 20 min. Some clusters consisting of needle-like crystal were observed in the spherical particles covering the surface, and the Ca/P ratio of the needle-like crystal was 1.46, clearly growing along the c axis preferred orientation growth. After immersion for 60 min, the FHA coating with

  3. Highly effective, regiospecific reduction of chalcone by cyanobacteria leads to the formation of dihydrochalcone: two steps towards natural sweetness.

    Science.gov (United States)

    Żyszka, Beata; Anioł, Mirosław; Lipok, Jacek

    2017-08-04

    Chalcones are the biogenetic precursors of all known flavonoids, which play an essential role in various metabolic processes in photosynthesizing organisms. The use of whole cyanobacteria cells in a two-step, light-catalysed regioselective bio-reduction of chalcone, leading to the formation of the corresponding dihydrochalcone, is reported. The prokaryotic microalgae cyanobacteria are known to produce phenolic compounds, including flavonoids, as natural components of cells. It seems logical that organisms producing such compounds possess a suitable "enzymatic apparatus" to carry out their biotransformation. Therefore, determination of the ability of whole cells of selected cyanobacteria to carry out biocatalytic transformations of chalcone, the biogenetic precursor of all known flavonoids, was the aim of our study. Chalcone was found to be converted to dihydrochalcone by all examined cyanobacterial strains; however, the effectiveness of this process depends on the strain with biotransformation yields ranging from 3% to >99%. The most effective biocatalysts are Anabaena laxa, Aphanizomenon klebahnii, Nodularia moravica, Synechocystis aquatilis (>99% yield) and Merismopedia glauca (92% yield). The strains Anabaena sp. and Chroococcus minutus transformed chalcone in more than one way, forming a few products; however, dihydrochalcone was the dominant product. The course of biotransformation shed light on the pathway of chalcone conversion, indicating that the process proceeds through the intermediate cis-chalcone. The scaled-up process, conducted on a preparative scale and by using a mini-pilot photobioreactor, fully confirmed the high effectiveness of this bioconversion. Moreover, in the case of the mini-pilot photobioreactor batch cultures, the optimization of culturing conditions allowed the shortening of the process conducted by A. klebahnii by 50% (from 8 to 4 days), maintaining its >99% yield. This is the first report related to the use of whole cells of

  4. The formation of FHA coating on biodegradable Mg-Zn-Zr alloy using a two-step chemical treatment method

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, S.T.; Zhang, J.; Shun, S.Z. [School of Materials Science and Engineering, Tianjin University of Technology, Tianjin (China); Chen, M.F., E-mail: mfchentj@126.com [School of Materials Science and Engineering, Tianjin University of Technology, Tianjin (China); Tianjin Key Laboratory of Display Materials and Photoelectric Device, Tianjin University of Technology , Tianjin (China)

    2016-12-01

    Highlights: • Use a two-step chemical treatment method for formation of FHA coating on biodegradable Mg-Zn-Zr alloy;. • We reported the formation mechanism of FHA coating on Mg-Zn-Zr alloy and achieved optimum properties;. • The MgF{sub 2} coating and FHA coating provide effective protection for the Mg alloy substrate and the FHA coating showed better corrosion resistance. - Abstract: To improve the corrosion resistance of the biomedical magnesium alloy, a two-step chemical treatment method has been employed to prepare an FHA coating on the alloy surface. Prior to forming an FHA layer, the samples of Mg-3 wt% Zn-0.5 wt% Zr alloy were soaked in HF with concentration of 20% (v/v) at 37 °C temperature for 2 h, and were then placed into an aqueous solution with 0.1 mol/L Ca(NO{sub 3}).4H{sub 2}O and 0.06 mol/L NH{sub 4}H{sub 2}PO{sub 4} at 90 °C to prepare the Ca-P coating. The concentrations of Mg{sup 2+}, F{sup −} ions, and pH variation with immersing time in the solution were investigated to explore the growth mechanism of FHA. The surface morphologies and compositions of the coatings were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. The results showed that the alloy surface treated with acid formed a layer of MgF{sub 2} nanoparticles with a thickness of 0.7 μm. The corrosion resistance of coatings in SBF solution was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The results showed that the substrate with FHA coating had good corrosion resistance. After immersing into the calcium phosphate solution, some small spherical particles were first formed on the surface; these then cover the surface completely after 20 min. Some clusters consisting of needle-like crystal were observed in the spherical particles covering the surface, and the Ca/P ratio of the needle-like crystal was 1.46, clearly growing along the c axis preferred orientation growth. After

  5. Specific acid catalysis and Lewis acid catalysis of Diels–Alder reactions in aqueous media

    NARCIS (Netherlands)

    Mubofu, Egid B.; Engberts, Jan B.F.N.

    2004-01-01

    A comparative study of specific acid catalysis and Lewis acid catalysis of Diels–Alder reactions between dienophiles (1, 4 and 6) and cyclopentadiene (2) in water and mixed aqueous media is reported. The reactions were performed in water with copper(II) nitrate as the Lewis acid catalyst whereas

  6. Specific acid catalysis and Lewis acid catalysis of Diels-Alder reactions in aqueous media

    NARCIS (Netherlands)

    Mubofu, E.B.; Engberts, J.B.F.N.

    A comparative study of specific acid catalysis and Lewis acid catalysis of Diells-Alder reactions between dienophiles (1, 4 and 6) and cyclopentadiene (2) in water and mixed aqueous media is reported. The reactions were performed in water with copper(II) nitrate as the Lewis acid catalyst whereas

  7. Heliostat-field gain-scheduling control applied to a two-step solar hydrogen production plant

    International Nuclear Information System (INIS)

    Roca, Lidia; Calle, Alberto de la; Yebra, Luis J.

    2013-01-01

    Highlights: ► A control system is proposed for a solar reactor system which produces hydrogen. ► The controller chooses which heliostats from the solar field must be focused. ► A gain scheduling scheme is included to deal with different system dynamics. ► The scheme is tested and tunned in simulation. ► Real experiments show the promising results of this work. -- Abstract: This article describes a temperature control structure designed for the interior of a solar hydrogen reactor based on a two-step ferrite-redox technology. Until now, this temperature has been controlled by manual selection of the heliostats to be focused on the receiver targets. However, the strong system dependency on operating conditions suggests that the procedure be automated in order to ensure the desired setpoint change response. The aims are to maintain the desired temperatures and to make the setpoint switch as fast as possible, keeping plant conditions within the margins of safety. The scheme proposed includes a procedure for selecting the heliostats to be focused on the reactor by using a simple model of the solar field and a gain scheduling control system which changes the control tuning parameters to deal with the varying dynamics observed during the process. Real experiments show the promising results of this work.

  8. The Effect of Two-Step Heat Treatment Parameters on Microstructure and Mechanical Properties of 42SiMn Steel

    Directory of Open Access Journals (Sweden)

    Ludmila Kučerová

    2017-12-01

    Full Text Available Medium-carbon steel 42SiMn (0.4C-0.6Mn-2Si-0.03Nb was used for a two-step heat treatment consisting of a soaking hold and an annealing hold at bainite transformation temperature. Various heating temperatures, cooling rates, and bainitic hold temperatures were applied to the steel to obtain microstructures typical for TRIP (Transformation Induced Plasticity steels. TRIP steels utilize the positive effects of a multiphase microstructure with retained austenite, creating a good combination of strength and total elongation and an excellent deep-drawing ability. Typical microstructures consist of ferrite, bainite, and 10–15% of retained austenite. In this work, tensile strengths in the region of 887–1063 MPa were achieved with total elongation A5mm of 26–47%, and the final microstructures contained 4–16% of retained austenite. The most suitable microstructure and the best combination of high strength and total elongation were achieved for the processing with intercritical heating temperature of 850 °C and cooling at 30 °C/s to the bainitic hold of 400 °C. Very fine pearlite persisted in the microstructures, even after applying a cooling rate of 50 °C/s, however these small areas with extremely fine laths did not prevent the retention of up to 16% of retained austenite, and high total elongation A5mm above 40% was still reached for these microstructures.

  9. The Security Analysis of Two-Step Quantum Direct Communication Protocol in Collective-Rotation Noise Channel

    International Nuclear Information System (INIS)

    Li Jian; Sun Feng-Qi; Pan Ze-Shi; Nie Jin-Rui; Chen Yan-Hua; Yuan Kai-Guo

    2015-01-01

    To analyze the security of two-step quantum direct communication protocol (QDCP) by using Einstein–Podolsky–Rosen pair proposed by Deng et al. [Phys. Rev. A 68 (2003) 042317] in collective-rotation noise channel, an excellent model of noise analysis is proposed. In the security analysis, the method of the entropy theory is introduced, and is compared with QDCP, an error rate point Q 0 (M : (Q 0 , 1.0)) is given. In different noise levels, if Eve wants to obtain the same amount of information, the error rate Q is distinguishable. The larger the noise level ϵ is, the larger the error rate Q is. When the noise level ϵ is lower than 11%, the high error rate is 0.153 without eavesdropping. Lastly, the security of the proposed protocol is discussed. It turns out that the quantum channel will be safe when Q < 0.153. Similarly, if error rate Q > 0.153 = Q 0 , eavesdropping information I > 1, which means that there exist eavesdroppers in the quantum channel, and the quantum channel will not be safe anymore. (paper)

  10. Testing a stepped care model for binge-eating disorder: a two-step randomized controlled trial.

    Science.gov (United States)

    Tasca, Giorgio A; Koszycki, Diana; Brugnera, Agostino; Chyurlia, Livia; Hammond, Nicole; Francis, Kylie; Ritchie, Kerri; Ivanova, Iryna; Proulx, Genevieve; Wilson, Brian; Beaulac, Julie; Bissada, Hany; Beasley, Erin; Mcquaid, Nancy; Grenon, Renee; Fortin-Langelier, Benjamin; Compare, Angelo; Balfour, Louise

    2018-05-24

    A stepped care approach involves patients first receiving low-intensity treatment followed by higher intensity treatment. This two-step randomized controlled trial investigated the efficacy of a sequential stepped care approach for the psychological treatment of binge-eating disorder (BED). In the first step, all participants with BED (n = 135) received unguided self-help (USH) based on a cognitive-behavioral therapy model. In the second step, participants who remained in the trial were randomized either to 16 weeks of group psychodynamic-interpersonal psychotherapy (GPIP) (n = 39) or to a no-treatment control condition (n = 46). Outcomes were assessed for USH in step 1, and then for step 2 up to 6-months post-treatment using multilevel regression slope discontinuity models. In the first step, USH resulted in large and statistically significant reductions in the frequency of binge eating. Statistically significant moderate to large reductions in eating disorder cognitions were also noted. In the second step, there was no difference in change in frequency of binge eating between GPIP and the control condition. Compared with controls, GPIP resulted in significant and large improvement in attachment avoidance and interpersonal problems. The findings indicated that a second step of a stepped care approach did not significantly reduce binge-eating symptoms beyond the effects of USH alone. The study provided some evidence for the second step potentially to reduce factors known to maintain binge eating in the long run, such as attachment avoidance and interpersonal problems.

  11. Temporary Stabilization with External Fixator in ‘Tripolar’ Configuration in Two Steps Treatment of Tibial Pilon Fractures

    Science.gov (United States)

    Daghino, Walter; Messina, Marco; Filipponi, Marco; Alessandro, Massè

    2016-01-01

    Background: The tibial pilon fractures represent a complex therapeutic problem for the orthopedic surgeon, given the frequent complications and outcomes disabling. The recent medical literature indicates that the best strategy to reduce amount of complications in tibial pilon fractures is two-stages procedure. We describe our experience in the primary stabilization of these fractures. Methods: We treated 36 cases with temporary external fixation in a simple configuration, called "tripolar": this is an essential structure (only three screws and three rods), that is possible to perform even without the availability of X-rays and with simple anesthesia or sedation. Results: We found a sufficient mechanical stability for the nursing post-operative, in absence of intraoperative and postoperative problems. The time between trauma and temporary stabilization ranged between 3 and 144 hours; surgical average time was 8.4 minutes. Definitive treatment was carried out with a delay of a minimum of 4 and a maximum of 15 days from the temporary stabilization, always without problems, both in case of ORIF (open reduction, internal fixation) or circular external fixation Conclusion: Temporary stabilization with external fixator in ‘tripolar’ configuration seems to be the most effective strategy in two steps treatment of tibial pilon fractures. These preliminary encouraging results must be confirmed by further studies with more cases. PMID:27123151

  12. Studies on allergoids from naturally occurring allergens. III. Preparation of ragweed pollen allergoids by aldehyde modification in two steps.

    Science.gov (United States)

    Marsh, D G; Norman, P S; Roebber, M; Lichtenstein, L M

    1981-12-01

    We have devised a new process for modifying heat-labile allergens, which employs a sequential "two-step" incubation at temperatures of 10 degree C and 30 degree to 32 degree C. This process was found to produce effective ragweed "allergoids" with low allergenicity and good immunogenicity, which makes them useful for the therapy of allergic humans. Modification with formaldehyde produced derivatives ("formallergoids") that were about 10-fold less allergenic in allergic humans (as measured by leukocyte histamine-release assay), and similarly or more immunogenic in guinea pigs, than glutaraldehyde-modified allergens ("glutarallergoids"). Further analysis by RAST inhibition showed that a ragweed formallergoid was sixfold less reactive than a glutarallergoid with a pool of human IgE antibodies. However, the formallergoid had retained the ability to induce a wide array of antibodies against native ragweed antigens, since rabbit anti-formallergoid serum was able to recognize at least 12 different ragweed antigens, including AgE. Gel-filtration experiments showed that both the formallergoid and glutarallergoid materials contained polymers having apparent molecular weights distributed around 260,000 and 230,000 daltons, respectively (approximate range 30,000 to 900,000 daltons). Our studies provide the immunochemical basis for the use of these allergoids in the therapy of allergic humans.

  13. Development of interface between MCNP-FISPACT-MCNP (IPR-MFM) based on rigorous two step method

    International Nuclear Information System (INIS)

    Shaw, A.K.; Swami, H.L.; Danani, C.

    2015-01-01

    In this work we present the development of interface tool between MCNP-FISPACT-MCNP (MFM) based on Rigorous Two Step method for the shutdown dose rate (SDDR) calculation. The MFM links MCNP radiation transport and the FISPACT inventory code through a suitable coupling scheme. MFM coupling scheme has three steps. In first step it picks neutron spectrum and total flux from MCNP output file to use as input parameter for FISPACT. It prepares the FISPACT input files by using irradiation history, neutron flux and neutron spectrum and then execute the FISPACT input file in the second step. Third step of MFM coupling scheme extracts the decay gammas from the FISPACT output file and prepares MCNP input file for decay gamma transport followed by execution of MCNP input file and estimation of SDDR. Here detailing of MFM methodology and flow scheme has been described. The programming language PYTHON has been chosen for this development of the coupling scheme. A complete loop of MCNP-FISPACT-MCNP has been developed to handle the simplified geometrical problems. For validation of MFM interface a manual cross-check has been performed which shows good agreements. The MFM interface also has been validated with exiting MCNP-D1S method for a simple geometry with 14 MeV cylindrical neutron source. (author)

  14. A two-step real-time PCR assay for quantitation and genotyping of human parvovirus 4.

    Science.gov (United States)

    Väisänen, E; Lahtinen, A; Eis-Hübinger, A M; Lappalainen, M; Hedman, K; Söderlund-Venermo, M

    2014-01-01

    Human parvovirus 4 (PARV4) of the family Parvoviridae was discovered in a plasma sample of a patient with an undiagnosed acute infection in 2005. Currently, three PARV4 genotypes have been identified, however, with an unknown clinical significance. Interestingly, these genotypes seem to differ in epidemiology. In Northern Europe, USA and Asia, genotypes 1 and 2 have been found to occur mainly in persons with a history of injecting drug use or other parenteral exposure. In contrast, genotype 3 appears to be endemic in sub-Saharan Africa, where it infects children and adults without such risk behaviour. In this study, a novel straightforward and cost-efficient molecular assay for both quantitation and genotyping of PARV4 DNA was developed. The two-step method first applies a single-probe pan-PARV4 qPCR for screening and quantitation of this relatively rare virus, and subsequently, only the positive samples undergo a real-time PCR-based multi-probe genotyping. The new qPCR-GT method is highly sensitive and specific regardless of the genotype, and thus being suitable for studying the clinical impact and occurrence of the different PARV4 genotypes. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Theoretical aspects of several successive two-step redox mechanisms in protein-film cyclic staircase voltammetry

    International Nuclear Information System (INIS)

    Gulaboski, Rubin; Kokoškarova, Pavlinka; Mitrev, Saša

    2012-01-01

    Highlights: ► Theoretical models for 2e− successive mechanisms are considered. ► The models are compatible for various metal-containing redox proteins. ► Diagnostic criteria are provided to recognize the particular redox mechanism. - Abstract: Protein-film voltammetry (PFV) is a versatile tool designed to provide insight into the enzymes physiological functions by studying the redox properties of various oxido-reductases with suitable voltammetric technique. The determination of the thermodynamic and kinetic parameters relevant to protein's physiological properties is achieved via methodologies established from theoretical considerations of various mechanisms in PFV. So far, the majority of the mathematical models in PFV have been developed for redox proteins undergoing a single-step electron transfer reactions. However, there are many oxido-reductases containing quinone moieties or polyvalent ions of transition metals like Mo, Mn, W, Fe or Co as redox centers, whose redox chemistry can be described only via mathematical models considering successive two-step electron transformation. In this work we consider theoretically the protein-film redox mechanisms of the EE (Electrochemical–Electrochemical), ECE (Electrochemical–Chemical–Electrochemical), and EECat (Electrochemical–Electrochemical–Catalytic) systems under conditions of cyclic staircase voltammetry. We also propose methodologies to determine the kinetics of electron transfer steps by all considered mechanisms. The experimentalists working with PFV can get large benefits from the simulated voltammograms given in this work.

  16. Two-Step Separation of Nostotrebin 6 from Cultivated Soil Cyanobacterium (Nostoc sp. by High Performance Countercurrent Chromatography

    Directory of Open Access Journals (Sweden)

    José Cheel

    2014-06-01

    Full Text Available High performance countercurrent chromatography (HPCCC was successfully applied for the separation of nostotrebin 6 from cultivated soil cyanobacteria in a two-step operation. A two-phase solvent system composed of n-hexane–ethyl acetate–methanol–water (4:5:4:5, v/v/v/v was employed for the HPCCC separation. In the first-step operation, its neutral upper phase was used as stationary phase and its basic lower phase (1% NH3 in lower phase was employed as mobile phase at a flow rate of 1 mL/min. In the second operation step, its neutral upper phase was used as stationary phase, whereas both its neutral lower phase and basic lower phase were employed as mobile phase with a linear gradient elution at a flow rate of 0.8 mL/min. The revolution speed and temperature of the separation column were 1,000 rpm and 30 °C, respectively. Using HPCCC followed by clean-up on Sephadex LH-20 gel, 4 mg of nostotrebin 6 with a purity of 99% as determined by HPLC/DAD-ESI-HRMS was obtained from 100 mg of crude extract. The chemical identity of the isolated compound was confirmed by comparing its spectroscopic data (UV, ESI-HRMS, ESI-HRMS2 with those of an authentic standard and data available in the literature.

  17. A Two-Step A/D Conversion and Column Self-Calibration Technique for Low Noise CMOS Image Sensors

    Directory of Open Access Journals (Sweden)

    Jaeyoung Bae

    2014-07-01

    Full Text Available In this paper, a 120 frames per second (fps low noise CMOS Image Sensor (CIS based on a Two-Step Single Slope ADC (TS SS ADC and column self-calibration technique is proposed. The TS SS ADC is suitable for high speed video systems because its conversion speed is much faster (by more than 10 times than that of the Single Slope ADC (SS ADC. However, there exist some mismatching errors between the coarse block and the fine block due to the 2-step operation of the TS SS ADC. In general, this makes it difficult to implement the TS SS ADC beyond a 10-bit resolution. In order to improve such errors, a new 4-input comparator is discussed and a high resolution TS SS ADC is proposed. Further, a feedback circuit that enables column self-calibration to reduce the Fixed Pattern Noise (FPN is also described. The proposed chip has been fabricated with 0.13 μm Samsung CIS technology and the chip satisfies the VGA resolution. The pixel is based on the 4-TR Active Pixel Sensor (APS. The high frame rate of 120 fps is achieved at the VGA resolution. The measured FPN is 0.38 LSB, and measured dynamic range is about 64.6 dB.

  18. Computational Prediction of Excited-State Carbon Tunneling in the Two Steps of Triplet Zimmerman Di-π-Methane Rearrangement.

    Science.gov (United States)

    Li, Xin; Liao, Tao; Chung, Lung Wa

    2017-11-22

    The photoinduced Zimmerman di-π-methane (DPM) rearrangement of polycyclic molecules to form synthetically useful cyclopropane derivatives was found experimentally to proceed in a triplet excited state. We have applied state-of-the-art quantum mechanical methods, including M06-2X, DLPNO-CCSD(T) and variational transition-state theory with multidimensional tunneling corrections, to an investigation of the reaction rates of the two steps in the triplet DPM rearrangement of dibenzobarrelene, benzobarrelene and barrelene. This study predicts a high probability of carbon tunneling in regions around the two consecutive transition states at 200-300 K, and an enhancement in the rates by 104-276/35-67% with carbon tunneling at 200/300 K. The Arrhenius plots of the rate constants were found to be curved at low temperatures. Moreover, the computed 12 C/ 13 C kinetic isotope effects were affected significantly by carbon tunneling and temperature. Our predictions of electronically excited-state carbon tunneling and two consecutive carbon tunneling are unprecedented. Heavy-atom tunneling in some photoinduced reactions with reactive intermediates and narrow barriers can be potentially observed at relatively low temperature in experiments.

  19. Behaviors of rice straw two-step liquefaction with sub/supercritical ethanol in carbon dioxide atmosphere.

    Science.gov (United States)

    Yang, Tianhua; Wang, Jian; Li, Bingshuo; Kai, Xingping; Xing, Wanli; Li, Rundong

    2018-06-01

    This study extended previous work investigating two-step liquefaction by supercritical ethanol of rice straw under CO 2 atmosphere at temperatures of 270-345 °C. Subcritical CO 2 -subcritical ethanol (SubCO 2 -SubEtOH) pretreatment decreased the content of lignin in the rice stalk from 22.94 to 21.43 wt%. The results showed that although oxygen-transfer reaction, transesterification, carbonylation, and other reactions may occur with the supercritical CO 2 -supercritical ethanol (ScCO 2 -ScEtOH) liquefaction reactions, transesterification was the main reaction. The "de-oxygen-transfer" reaction mainly comprised de-oxygenation and decarboxylation. For temperatures exceeding 320 °C, the bio-oil yield decreased because the effects of esters decreased. The residence time affected the H/C and O/C ratios to a minor extent. It was shown that the nucleophilic and hydrolytic functions of ethanol might be strengthened, generating higher amounts of ester, phenolic, acidic, and hydrocarbon derivatives in the bio-oil fraction. Copyright © 2018 Elsevier Ltd. All rights reserved.

  20. Cavitation assisted synthesis of fatty acid methyl esters from sustainable feedstock in presence of heterogeneous catalyst using two step process.

    Science.gov (United States)

    Dubey, Sumit M; Gole, Vitthal L; Gogate, Parag R

    2015-03-01

    The present work reports the intensification aspects for the synthesis of fatty acid methyl esters (FAME) from a non-edible high acid value Nagchampa oil (31 mg of KOH/g of oil) using two stage acid esterification (catalyzed by H₂SO₄) followed by transesterification in the presence of heterogeneous catalyst (CaO). Intensification aspects of both stages have been investigated using sonochemical reactors and the obtained degree of intensification has been established by comparison with the conventional approach based on mechanical agitation. It has been observed that reaction temperature for esterification reduced from 65 to 40 °C for the ultrasonic approach whereas there was a significant reduction in the optimum reaction time for transesterification from 4h for the conventional approach to 2.5h for the ultrasound assisted approach. Also the reaction temperature reduced marginally from 65 to 60 °C and yield increased from 76% to 79% for the ultrasound assisted approach. Energy requirement and activation energy for both esterification and transesterification was lower for the ultrasound based approach as compared to the conventional approach. The present work has clearly established the intensification obtained due to the use of ultrasound and also illustrated the two step approach for the synthesis of FAME from high acid value feedstock based on the use of heterogeneous catalyst for the transesterification step. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Two-step source tracing strategy of Yersinia pestis and its historical epidemiology in a specific region.

    Directory of Open Access Journals (Sweden)

    Yanfeng Yan

    Full Text Available Source tracing of pathogens is critical for the control and prevention of infectious diseases. Genome sequencing by high throughput technologies is currently feasible and popular, leading to the burst of deciphered bacterial genome sequences. Utilizing the flooding genomic data for source tracing of pathogens in outbreaks is promising, and challenging as well. Here, we employed Yersinia pestis genomes from a plague outbreak at Xinghai county of China in 2009 as an example, to develop a simple two-step strategy for rapid source tracing of the outbreak. The first step was to define the phylogenetic position of the outbreak strains in a whole species tree, and the next step was to provide a detailed relationship across the outbreak strains and their suspected relatives. Through this strategy, we observed that the Xinghai plague outbreak was caused by Y. pestis that circulated in the local plague focus, where the majority of historical plague epidemics in the Qinghai-Tibet Plateau may originate from. The analytical strategy developed here will be of great help in fighting against the outbreaks of emerging infectious diseases, by pinpointing the source of pathogens rapidly with genomic epidemiological data and microbial forensics information.

  2. THEODORE, a two-step heating system for the EC/OC determination of radiocarbon (14C) in the environment

    International Nuclear Information System (INIS)

    Szidat, S.; Jenk, T.M.; Gaeggeler, H.W.; Synal, H.-A.; Hajdas, I.; Bonani, G.; Saurer, M.

    2004-01-01

    Measurements of 14 C in the organic carbon (OC) and elemental carbon (EC) fractions, respectively, of fine aerosol particles bear the potential to apportion anthropogenic and biogenic emission sources. For this purpose, the system THEODORE (two-step heating system for the EC/OC determination of radiocarbon in the environment) was developed. In this device, OC and EC are transformed into carbon dioxide in a stream of oxygen at 340 and 650 deg. C, respectively, and reduced to filamentous carbon. This is the target material for subsequent accelerator mass spectrometry (AMS) 14 C measurements, which were performed on sub-milligram carbon samples at the PSI/ETH compact 500 kV AMS system. Quality assurance measurements of SRM 1649a, Urban Dust, yielded a fraction of modern f M in total carbon (TC) of 0.522 ± 0.018 (n=5, 95% confidence level) in agreement with reported values. The results for OC and EC are 0.70 ± 0.05 (n=3) and 0.066 ± 0.020 (n=4), respectively

  3. An optimized two-step derivatization method for analyzing diethylene glycol ozonation products using gas chromatography and mass spectrometry.

    Science.gov (United States)

    Yu, Ran; Duan, Lei; Jiang, Jingkun; Hao, Jiming

    2017-03-01

    The ozonation of hydroxyl compounds (e.g., sugars and alcohols) gives a broad range of products such as alcohols, aldehydes, ketones, and carboxylic acids. This study developed and optimized a two-step derivatization procedure for analyzing polar products of aldehydes and carboxylic acids from the ozonation of diethylene glycol (DEG) in a non-aqueous environment using gas chromatography-mass spectrometry. Experiments based on Central Composite Design with response surface methodology were carried out to evaluate the effects of derivatization variables and their interactions on the analysis. The most desirable derivatization conditions were reported, i.e., oximation was performed at room temperature overnight with the o-(2,3,4,5,6-pentafluorobenzyl) hydroxyl amine to analyte molar ratio of 6, silylation reaction temperature of 70°C, reaction duration of 70min, and N,O-bis(trimethylsilyl)-trifluoroacetamide volume of 12.5μL. The applicability of this optimized procedure was verified by analyzing DEG ozonation products in an ultrafine condensation particle counter simulation system. Copyright © 2016. Published by Elsevier B.V.

  4. Effective Identification of Akt Interacting Proteins by Two-Step Chemical Crosslinking, Co-Immunoprecipitation and Mass Spectrometry

    Science.gov (United States)

    Huang, Bill X.; Kim, Hee-Yong

    2013-01-01

    Akt is a critical protein for cell survival and known to interact with various proteins. However, Akt binding partners that modulate or regulate Akt activation have not been fully elucidated. Identification of Akt-interacting proteins has been customarily achieved by co-immunoprecipitation combined with western blot and/or MS analysis. An intrinsic problem of the method is loss of interacting proteins during procedures to remove non-specific proteins. Moreover, antibody contamination often interferes with the detection of less abundant proteins. Here, we developed a novel two-step chemical crosslinking strategy to overcome these problems which resulted in a dramatic improvement in identifying Akt interacting partners. Akt antibody was first immobilized on protein A/G beads using disuccinimidyl suberate and allowed to bind to cellular Akt along with its interacting proteins. Subsequently, dithiobis[succinimidylpropionate], a cleavable crosslinker, was introduced to produce stable complexes between Akt and binding partners prior to the SDS-PAGE and nanoLC-MS/MS analysis. This approach enabled identification of ten Akt partners from cell lysates containing as low as 1.5 mg proteins, including two new potential Akt interacting partners. None of these but one protein was detectable without crosslinking procedures. The present method provides a sensitive and effective tool to probe Akt-interacting proteins. This strategy should also prove useful for other protein interactions, particularly those involving less abundant or weakly associating partners. PMID:23613850

  5. Formation Dynamics of CH3NH3PbI3 Perovskite Following Two-Step Layer Deposition.

    Science.gov (United States)

    Patel, Jay B; Milot, Rebecca L; Wright, Adam D; Herz, Laura M; Johnston, Michael B

    2016-01-07

    Hybrid metal-halide perovskites have emerged as a leading class of semiconductors for optoelectronic devices because of their desirable material properties and versatile fabrication methods. However, little is known about the chemical transformations that occur in the initial stages of perovskite crystal formation. Here we follow the real-time formation dynamics of MAPbI3 from a bilayer of lead iodide (PbI2) and methylammonium iodide (MAI) deposited through a two-step thermal evaporation process. By lowering the substrate temperature during deposition, we are able to initially inhibit intermixing of the two layers. We subsequently use infrared and visible light transmission, X-ray diffraction, and photoluminescence lifetime measurements to reveal the room-temperature transformations that occur in vacuum and ambient air, as MAI diffuses into the PbI2 lattice to form MAPbI3. In vacuum, the transformation to MAPbI3 is incomplete as unreacted MAI is retained in the film. However, exposure to moist air allows for conversion of the unreacted MAI to MAPbI3, demonstrating that moisture is essential in making MAI more mobile and thus aiding perovskite crystallization. These dynamic processes are reflected in the observed charge-carrier lifetimes, which strongly fluctuate during periods of large ion migration but steadily increase with improving crystallinity.

  6. Two-Step Hydrothermal Synthesis of Bifunctional Hematite-Silver Heterodimer Nanoparticles for Potential Antibacterial and Anticancer Applications

    Science.gov (United States)

    Trang, Vu Thi; Tam, Le Thi; Phan, Vu Ngoc; Van Quy, Nguyen; Huy, Tran Quang; Le, Anh-Tuan

    2017-06-01

    In recent years, the development of composite nanostructures containing noble metal and magnetic nanocrystals has attracted much interest because they offer a promising avenue for multifunctional applications in nanomedicine and pharmacotherapy. In this work, we present a facile two-step hydrothermal approach for the synthesis of bifunctional heterodimer nanoparticles (HDNPs) composed of hematite nanocubes (α-Fe2O3 NCs) and silver nanoparticles (Ag-NPs). The formation and magnetic property of α-Fe2O3-Ag HDNPs was analyzed by transmission electron microscopy, x-ray diffraction and vibrating sample magnetometer. Interestingly, the hydrothermal-synthesized α-Fe2O3-Ag HDNPs were found to display significant antibacterial activity against three types of infectious bacteria. The cytotoxicity of α-Fe2O3-Ag nanocomposite against lung cancer A549 cell line was investigated and compared with that of pure α-Fe2O3 NCs and Ag-NPs. The obtained results reveal that the α-Fe2O3-Ag nanocomposite exhibited higher anticancer performance than that of pure Ag-NPs, whereas pure α-Fe2O3 NCs were not cytotoxic to the tested cells. The inhibitory concentration (IC50) of the α-Fe2O3-Ag nanocomposite was found at 20.94 μg/mL. With the aforementioned properties, α-Fe2O3-Ag HDNPs showed a high potential as a multifunctional material for advanced biomedicine and nanotherapy applications.

  7. A new heat transfer analysis in machining based on two steps of 3D finite element modelling and experimental validation

    Science.gov (United States)

    Haddag, B.; Kagnaya, T.; Nouari, M.; Cutard, T.

    2013-01-01

    Modelling machining operations allows estimating cutting parameters which are difficult to obtain experimentally and in particular, include quantities characterizing the tool-workpiece interface. Temperature is one of these quantities which has an impact on the tool wear, thus its estimation is important. This study deals with a new modelling strategy, based on two steps of calculation, for analysis of the heat transfer into the cutting tool. Unlike the classical methods, considering only the cutting tool with application of an approximate heat flux at the cutting face, estimated from experimental data (e.g. measured cutting force, cutting power), the proposed approach consists of two successive 3D Finite Element calculations and fully independent on the experimental measurements; only the definition of the behaviour of the tool-workpiece couple is necessary. The first one is a 3D thermomechanical modelling of the chip formation process, which allows estimating cutting forces, chip morphology and its flow direction. The second calculation is a 3D thermal modelling of the heat diffusion into the cutting tool, by using an adequate thermal loading (applied uniform or non-uniform heat flux). This loading is estimated using some quantities obtained from the first step calculation, such as contact pressure, sliding velocity distributions and contact area. Comparisons in one hand between experimental data and the first calculation and at the other hand between measured temperatures with embedded thermocouples and the second calculation show a good agreement in terms of cutting forces, chip morphology and cutting temperature.

  8. Near-Space TOPSAR Large-Scene Full-Aperture Imaging Scheme Based on Two-Step Processing

    Directory of Open Access Journals (Sweden)

    Qianghui Zhang

    2016-07-01

    Full Text Available Free of the constraints of orbit mechanisms, weather conditions and minimum antenna area, synthetic aperture radar (SAR equipped on near-space platform is more suitable for sustained large-scene imaging compared with the spaceborne and airborne counterparts. Terrain observation by progressive scans (TOPS, which is a novel wide-swath imaging mode and allows the beam of SAR to scan along the azimuth, can reduce the time of echo acquisition for large scene. Thus, near-space TOPS-mode SAR (NS-TOPSAR provides a new opportunity for sustained large-scene imaging. An efficient full-aperture imaging scheme for NS-TOPSAR is proposed in this paper. In this scheme, firstly, two-step processing (TSP is adopted to eliminate the Doppler aliasing of the echo. Then, the data is focused in two-dimensional frequency domain (FD based on Stolt interpolation. Finally, a modified TSP (MTSP is performed to remove the azimuth aliasing. Simulations are presented to demonstrate the validity of the proposed imaging scheme for near-space large-scene imaging application.

  9. Ceria-based electrospun fibers for renewable fuel production via two-step thermal redox cycles for carbon dioxide splitting.

    Science.gov (United States)

    Gibbons, William T; Venstrom, Luke J; De Smith, Robert M; Davidson, Jane H; Jackson, Gregory S

    2014-07-21

    Zirconium-doped ceria (Ce(1-x)Zr(x)O2) was synthesized through a controlled electrospinning process as a promising approach to cost-effective, sinter-resistant material structures for high-temperature, solar-driven thermochemical redox cycles. To approximate a two-step redox cycle for solar fuel production, fibrous Ce(1-x)Zr(x)O2 with relatively low levels of Zr-doping (0 rates of O2 release during reduction and CO production during reoxidation and by assessing post-cycling fiber crystallite sizes and surface areas. Sintering increases with reduction temperature but occurs primarily along the fiber axes. Even after 108 redox cycles with reduction at 1400 °C and oxidation with CO2 at 800 °C, the fibers maintain their structure with surface areas of ∼0.3 m(2) g(-1), higher than those observed in the literature for other ceria-based structures operating at similarly high temperature conditions. Total CO production and peak production rate stabilize above 3.0 mL g(-1) and 13.0 mL min(-1) g(-1), respectively. The results show the potential for electrospun oxides as sinter-resistant material structures with adequate surface area to support rapid CO2 splitting in solar thermochemical redox cycles.

  10. Novel strategy for immunomodulation: Dissolving microneedle array encapsulating thymopentin fabricated by modified two-step molding technology.

    Science.gov (United States)

    Lin, Shiqi; Cai, Bingzhen; Quan, Guilan; Peng, Tingting; Yao, Gangtao; Zhu, Chune; Wu, Qiaoli; Ran, Hao; Pan, Xin; Wu, Chuanbin

    2018-01-01

    Thymopentin (TP5) is commonly used in the treatment for autoimmune diseases, with a short plasma half-life (30s) and a long treatment period (7 days to 6 months). It is usually administrated by syringe injection, resulting in compromised patient compliance. Dissolving microneedle array (DMNA) offers a superior approach for transdermal delivery of biological macromolecules, as it allows painless penetration through the stratum corneum and generates minimal biohazardous waste after dissolving in the skin. Despite recent advances in DMNA as a novel approach for transdermal drug delivery, problem of insufficient mechanical strength remains to be solved. In this study, TP5-loaded DMNA (TP5-DMNA) was uniquely developed using a modified two-step molding technology. The higher mechanical strength was furnished by employing bovine serum albumin (BSA) as a co-material to fabricate the needles. The obtained TP5-DMNA containing BSA displayed better skin penetration and higher drug loading efficiency than that without BSA. The in vivo pharmacodynamics study demonstrated that TP5-DMNA had comparative effect on immunomodulation to intravenous injection of TP5, in terms of ameliorating the CD4+/CD8+ ratio, SOD activity and MDA value to the basal level. Only mild irritation was observed at the site of administration. These results suggest that the novel TP5-DMNA utilizing BSA provides an alternative approach for convenient and safe transdermal delivery of TP5, which is a promising administration strategy for future clinical application. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Biohydrogen and methane production via a two-step process using an acid pretreated native microalgae consortium.

    Science.gov (United States)

    Carrillo-Reyes, Julian; Buitrón, Germán

    2016-12-01

    A native microalgae consortium treated under thermal-acidic hydrolysis was used to produce hydrogen and methane in a two-step sequential process. Different acid concentrations were tested, generating hydrogen and methane yields of up to 45mLH 2 gVS -1 and 432mLCH 4 gVS -1 , respectively. The hydrogen production step solubilized the particulate COD (chemical oxygen demand) up to 30%, creating considerable amounts of volatile fatty acids (up to 10gCODL -1 ). It was observed that lower acid concentration presented higher hydrogen and methane production potential. The results revealed that thermal acid hydrolysis of a native microalgae consortium is a simple but effective strategy for producing hydrogen and methane in the sequential process. In addition to COD removal (50-70%), this method resulted in an energy recovery of up to 15.9kJ per g of volatile solids of microalgae biomass, one of the highest reported. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Two-step polymer- and liposome-enzyme prodrug therapies for cancer: PDEPT and PELT concepts and future perspectives.

    Science.gov (United States)

    Scomparin, Anna; Florindo, Helena F; Tiram, Galia; Ferguson, Elaine L; Satchi-Fainaro, Ronit

    2017-09-01

    Polymer-directed enzyme prodrug therapy (PDEPT) and polymer enzyme liposome therapy (PELT) are two-step therapies developed to provide anticancer drugs site-selective intratumoral accumulation and release. Nanomedicines, such as polymer-drug conjugates and liposomal drugs, accumulate in the tumor site due to extravasation-dependent mechanism (enhanced permeability and retention - EPR - effect), and further need to cross the cellular membrane and release their payload in the intracellular compartment. The subsequent administration of a polymer-enzyme conjugate able to accumulate in the tumor tissue and to trigger the extracellular release of the active drug showed promising preclinical results. The development of polymer-enzyme, polymer-drug conjugates and liposomal drugs had undergone a vast advancement over the past decades. Several examples of enzyme mimics for in vivo therapy can be found in the literature. Moreover, polymer therapeutics often present an enzyme-sensitive mechanism of drug release. These nanomedicines can thus be optimal substrates for PDEPT and this review aims to provide new insights and stimuli toward the future perspectives of this promising combination. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Long-Time Plasma Membrane Imaging Based on a Two-Step Synergistic Cell Surface Modification Strategy.

    Science.gov (United States)

    Jia, Hao-Ran; Wang, Hong-Yin; Yu, Zhi-Wu; Chen, Zhan; Wu, Fu-Gen

    2016-03-16

    Long-time stable plasma membrane imaging is difficult due to the fast cellular internalization of fluorescent dyes and the quick detachment of the dyes from the membrane. In this study, we developed a two-step synergistic cell surface modification and labeling strategy to realize long-time plasma membrane imaging. Initially, a multisite plasma membrane anchoring reagent, glycol chitosan-10% PEG2000 cholesterol-10% biotin (abbreviated as "GC-Chol-Biotin"), was incubated with cells to modify the plasma membranes with biotin groups with the assistance of the membrane anchoring ability of cholesterol moieties. Fluorescein isothiocyanate (FITC)-conjugated avidin was then introduced to achieve the fluorescence-labeled plasma membranes based on the supramolecular recognition between biotin and avidin. This strategy achieved stable plasma membrane imaging for up to 8 h without substantial internalization of the dyes, and avoided the quick fluorescence loss caused by the detachment of dyes from plasma membranes. We have also demonstrated that the imaging performance of our staining strategy far surpassed that of current commercial plasma membrane imaging reagents such as DiD and CellMask. Furthermore, the photodynamic damage of plasma membranes caused by a photosensitizer, Chlorin e6 (Ce6), was tracked in real time for 5 h during continuous laser irradiation. Plasma membrane behaviors including cell shrinkage, membrane blebbing, and plasma membrane vesiculation could be dynamically recorded. Therefore, the imaging strategy developed in this work may provide a novel platform to investigate plasma membrane behaviors over a relatively long time period.

  14. Prenylcoumarins in One or Two Steps by a Microwave-Promoted Tandem Claisen Rearrangement/Wittig Olefination/Cyclization Sequence.

    Science.gov (United States)

    Schultze, Christiane; Schmidt, Bernd

    2018-05-04

    The one-pot synthesis of 8-prenylcoumarins from 1,1-dimethylallylated salicylaldehydes and the stabilized ylide [(ethoxycarbonyl)methylene]triphenylphosphorane under microwave conditions was found to have a limited scope. The sequence suffers from a difficult and sometimes low-yielding synthesis of the precursors and from a competing deprenylation upon microwave irradiation. This side reaction occurs in particular with electron rich arenes with two or more alkoxy groups at adjacent positions, a prominent substitution pattern in naturally occurring 8-prenylcoumarins. Both limitations of this one-step sequence were overcome by a two-step synthesis consisting of a microwave-promoted tandem allyl ether Claisen rearrangement/Wittig olefination and a subsequent olefin cross metathesis with 2-methyl-2-butene. The cross metathesis step proceeds with a high selectivity and yields exclusively the desired prenyl, rather than the alternative crotyl substituent. Several naturally occurring 8-prenylcoumarins that were previously inaccessible have been synthesized in good overall yields along this route.

  15. Two-step design method for highly compact three-dimensional freeform optical system for LED surface light source.

    Science.gov (United States)

    Mao, Xianglong; Li, Hongtao; Han, Yanjun; Luo, Yi

    2014-10-20

    Designing an illumination system for a surface light source with a strict compactness requirement is quite challenging, especially for the general three-dimensional (3D) case. In accordance with the two key features of an expected illumination distribution, i.e., a well-controlled boundary and a precise illumination pattern, a two-step design method is proposed in this paper for highly compact 3D freeform illumination systems. In the first step, a target shape scaling strategy is combined with an iterative feedback modification algorithm to generate an optimized freeform optical system with a well-controlled boundary of the target distribution. In the second step, a set of selected radii of the system obtained in the first step are optimized to further improve the illuminating quality within the target region. The method is quite flexible and effective to design highly compact optical systems with almost no restriction on the shape of the desired target field. As examples, three highly compact freeform lenses with ratio of center height h of the lens and the maximum dimension D of the source ≤ 2.5:1 are designed for LED surface light sources to form a uniform illumination distribution on a rectangular, a cross-shaped and a complex cross pierced target plane respectively. High light control efficiency of η > 0.7 as well as low relative standard illumination deviation of RSD < 0.07 is obtained simultaneously for all the three design examples.

  16. Lipase - Catalyzed glycerolysis of sunflower oil to produce partial glycerides.

    Directory of Open Access Journals (Sweden)

    Zaher, F. A.

    1998-12-01

    Full Text Available Partial glycerides were prepared by glycerolysis of sunflower oil in presence of lipase enzyme as catalyst. Six lipases of different origins were used and compared for their catalytic activity. These include Chromobacterium lipase, pancreatic lipase, Rhizopus arrhizus lipase, lyophilized lipase (plant lipase in addition to two lipase preparations derived from Rhizopus japonicas; Lilipase A-10 and Lilipase B-2. Chromobacterium lipase was found to be the most active as glycerolysis catalyst whereas lyophilized lipase; a plant preparation from wheat germ was the least active. The results have also shown that the lipase type affects also the product polarity and hence its field of application as a food emulsifier. Less polar products can be obtained using Chromobacterium lipase whereas the more polar ones using a fungal lipase preparation «Lipase A-10». The product polarity is also influenced by the process temperature but the mode of its effect is different for different lipases.

    Se prepararon glicéridos parciales mediante glicerolisis de aceite de girasol en presencia de lipasa como catalizador. Seis lipasas de orígenes diferentes se utilizaron y compararon en función de su actividad catalítica. Estas incluyeron lipasa de Chromobacterium, lipasa pancreática, lipasa de Rhizopus arrhizus, lipasa liofilizada (lipasa vegetal además de dos preparaciones de lipasa derivadas de Rhizopus japonicus: lilipase A-10 y lilipase B-2. Se encontró que la lipasa de Chromobacterium fue la más activa como catalizador en la glicerolisis mientras que la lipasa liofilizada, preparación vegetal a partir de germen de trigo, fue la menos activa. Los resultados mostraron que los tipos de lipasa afectan también a la polaridad de los productos y por tanto a los rendimientos en su aplicación como emulsificantes alimentarios. Los productos menos polares pueden obtenerse usando lipasa de

  17. Butyl acetate synthesis using immobilized lipase in calcium alginate beads

    International Nuclear Information System (INIS)

    Mohd Zulkhairi Abdul Rahim; Lee, Pat M.; Lee, Kong H.

    2008-01-01

    The esterification reaction of acetic acid and n-butanol using immobilized lipase encapsulated in calcium alginate beads (Lipase - CAB) and in chitosan coated calcium alginate beads (Lipase-CCAB) in n-hexane under mild reaction conditions were studied. Effects of temperature and substrate concentration (acetic acid and n-butanol) using Lipase - CAB, Lipase - CCAB and free lipase on the esterification reaction and their thermal stability towards esterification reaction were investigated. Results of temperature studies showed that the butyl acetate conversion increased with increase of temperature and reached the highest yield of about 70% around 50 degree Celsius for both immobilized systems but the yield of product catalyzed by free enzyme decreased as temperature was increased. Thermal stabilities studies showed that the Lipase-CCAB and Lipase-CAB were stable throughout the temperature range of 30-60 degree Celsius. However, free lipase became less stable at temperatures higher than 50 degree Celsius. The substrates, n-butanol and acetic acid exerted different effects on the esterification reaction and the reaction was favoured by higher acetic acid concentration than butanol. Kinetics parameters, Km and Vmax values for both substrates and the specific activities of the three enzyme system were also determined. The beads morphology was examined using SEM. Batch-wise operational stability studies for both immobilized systems demonstrated that the immobilized lipase performed better in the batch wise reactor system than the continuous bioreactor system and that the immobilized lipase remained active for at least 5 cycles of batch wise esterification reactions. (author)

  18. Nano catalysis: Academic Discipline and Industrial Realities

    International Nuclear Information System (INIS)

    Olveira, S.; Forster, S.P.; Seeger, S.

    2014-01-01

    Nano technology plays a central role in both academic research and industrial applications. Nano enabled products are not only found in consumer markets, but also importantly in business to business markets (B2B). One of the oldest application areas of nano technology is nano catalysis—an excellent example for such a B2 B market. Several existing reviews illustrate the scientific developments in the field of nano catalysis. The goal of the present review is to provide an up-to-date picture of academic research and to extend this picture by an industrial and economic perspective. We therefore conducted an extensive search on several scientific databases and we further analyzed more than 1,500 nano catalysis-related patents and numerous market studies. We found that scientists today are able to prepare nano catalysts with superior characteristics regarding activity, selectivity, durability, and recoverability, which will contribute to solve current environmental, social, and industrial problems. In industry, the potential of nano catalysis is recognized, clearly reflected by the increasing number of nano catalysis-related patents and products on the market. The current nano catalysis research in academic and industrial laboratories will therefore enable a wealth of future applications in the industry

  19. Comparison of enamel bond fatigue durability between universal adhesives and two-step self-etch adhesives: Effect of phosphoric acid pre-etching.

    Science.gov (United States)

    Suda, Shunichi; Tsujimoto, Akimasa; Barkmeier, Wayne W; Nojiri, Kie; Nagura, Yuko; Takamizawa, Toshiki; Latta, Mark A; Miyazaki, Masashi

    2018-03-30

    The effect of phosphoric acid pre-etching on enamel bond fatigue durability of universal adhesives and two-step self-etch adhesives was investigated. Four universal adhesives and three two-step self-etch adhesives were used. The initial shear bond strengths and shear fatigue strengths to enamel with and without phosphoric acid pre-etching using the adhesives were determined. SEM observations were also conducted. Phosphoric acid pre-etching of enamel was found to increase the bond fatigue durability of universal adhesives, but its effect on two-step self-etch adhesives was material-dependent. In addition, some universal adhesives with phosphoric acid pre-etching showed similar bond fatigue durability to the two-step self-etch adhesives, although the bond fatigue durability of universal adhesives in self-etch mode was lower than that of the two-step self-etch adhesives. Phosphoric acid pre-etching enhances enamel bond fatigue durability of universal adhesives, but the effect of phosphoric acid pre-etching on the bond fatigue durability of two-step self-etch adhesives was material-dependent.

  20. In silico modeling of lipase H | Jabeen | African Journal of ...

    African Journals Online (AJOL)

    LAH 2 is a type of autosomal recessive hypotrichosis that affect hairs, eyebrows, scalp and eyelashes. Mutations in Lipase H gene result in LAH 2. Changes that result from mutation on physiochemical properties, post-translational modifications, functional sites, secondary structure and tertiary structure lipase H gene (LIPH) ...

  1. Plant latex lipase as biocatalysts for biodiesel production | Mazou ...

    African Journals Online (AJOL)

    Plant latex lipase as biocatalysts for biodiesel production. ... This paper provides an overview regarding the main aspects of latex, such as the reactions catalyzed, physiological functions, specificities, sources and their industrial applications. Keywords: Plant latex, lipase, Transesterification, purification, biodiesel ...

  2. Screening of thermophilic neutral lipase-producing Pseudomonas ...

    African Journals Online (AJOL)

    From oil-contaminated soil, three lipase-producing microorganisms were selected as good lipase producers using rhodamine B-olive oil plate agar and they were identified as from Pseudomonas, Burkholderia and Klebsiella genera by morphology, biochemical characterization and 16S rRNA gene sequencing. Among the ...

  3. Structural investigations of the regio- and enantioselectivity of lipases

    NARCIS (Netherlands)

    Lang, Dietmar A.; Dijkstra, Bauke W.

    Although lipases are widely applied for the stereospecific resolution of racemic mixtures of esters, the atomic details of the factors that are responsible for their stereospecificity are largely obscure. We determined the X-ray structures of Pseudomonas cepacia lipase in complex with two

  4. Production of extracellular lipase by a new strain Staphylococcus ...

    African Journals Online (AJOL)

    Based on morphological, biochemical and 16S rRNA sequence analysis, the potent isolate was identified as Staphylococcus aureus. The lipase production of the isolate was increased by improving the conditions of production medium. Maximum lipase production (8.11 U/ml) was achieved when 2% punnakka oil was ...

  5. Isolation and characterization of lipase-producing Bacillus strains ...

    African Journals Online (AJOL)

    Bacillus strains (B1 - B5) producing extra cellular lipase were isolated from the soil sample of coconut oil industry. The strains were identified by morphological and biochemical characters. Growth of the organisms and lipase production were measured with varying pH (4 - 9) temperature (27, 37 and 47ºC) and various ...

  6. Enzymes used in detergents: Lipases | Hasan | African Journal of ...

    African Journals Online (AJOL)

    This review describes the applications of microbial lipases in detergents. Enzymes can reduce the environmental load of detergent products as the chemicals used in conventional detergents are reduced; they are biodegradable, non-toxic and leave no harmful residues. Besides lipases, other enzymes are widely used in ...

  7. Structural basis of the chiral selectivity of Pseudomonas cepacia lipase

    NARCIS (Netherlands)

    Lang, Dietmar A.; Mannesse, Maurice L.M.; Haas, Gerard H. de; Verheij, Hubertus M.; Dijkstra, Bauke W.

    1998-01-01

    To investigate the enantioselectivity of Pseudomonas cepacia lipase, inhibition studies were performed with S(c)-and R(c)-(R(p),S(p))-1,2-dialkylcarbamoylglycero-3-O-p-nitrophenyl alkylphosphonates of different alkyl chain lengths. P. cepacia lipase was most rapidly inactivated by

  8. Chicken fat and inorganic nitrogen source for lipase production by ...

    African Journals Online (AJOL)

    SAM

    2014-03-19

    Mar 19, 2014 ... for lipase production, the production cost was $US 518.00/million Units of lipase. Key words: ... energetics, fine chemicals and pulp and paper industries. ... for enzyme production is extremely important in dictating ... fat is waste product of poultry processing industry ... Economic Research Service,” 2013).

  9. Purification and Characterization of Lipase from Aspergillus flavus ...

    African Journals Online (AJOL)

    USER

    Abstract. Lipase from Aspergillus flavus was purified in a single step purification using MnFeO4 magnetic nano particles to achieve a 20.53- fold purification with specific activity of. 11.29 U/mg and a 59% recovery yield. SDS-PAGE of lipase showed a single pure band with corresponding molecular weight of 35 kDa.

  10. Lipase Activity in Fermented Oil Seeds of Africa Locust Bean ...

    African Journals Online (AJOL)

    acer

    was determined. The peak lipase activity for fermented Africa locust bean, Castor seed, and African ..... Lipase by Penicillium restrictum in solid state ... sp. Rev. Microbiol. 28(2): 90-95. Martinek, G.H. (1969). Microbiology and amino acid ...

  11. Optimization of lipase production by Staphylococcus sp. Lp12

    African Journals Online (AJOL)

    USER

    2010-02-08

    Feb 8, 2010 ... of the genera Pseudomonas, Bacillus, Staphylococcus,. Achromobacter have been cloned and characterized. Bacterial lipases are mostly inducible enzymes and require some form of oil, fatty acid, fatty acid alcohol or fatty acid ester and surfactants for induction (Immanuel et al., 2008). Lipase biosynthesis ...

  12. Characteristics of lipase isolated from coconut (Cocos nucifera linn ...

    African Journals Online (AJOL)

    GREGO

    2007-03-19

    Mar 19, 2007 ... Lipase from coconut plant grown under complete nutrient conditions showed ... 35°C and had a broad optimum pH of 7.5 – 8.5. Key words: Lipase .... inhibited by the ex- cess of substrate concentration or change of physio-.

  13. Endothelial and lipoprotein lipases in human and mouse placenta

    DEFF Research Database (Denmark)

    Lindegaard, Marie L S; Olivecrona, Gunilla; Christoffersen, Christina

    2005-01-01

    Placenta expresses various lipase activities. However, a detailed characterization of the involved genes and proteins is lacking. In this study, we compared the expression of endothelial lipase (EL) and LPL in human term placenta. When placental protein extracts were separated by heparin-Sepharos...

  14. Effect of Ascorbic Acid on Lipoprotein Lipase Activity | Kotze | South ...

    African Journals Online (AJOL)

    Baboons kept on hypovitaminotic C diets, but without clinical signs of scurvy, had significantly higher heart muscle lipoprotein lipase activity than baboons on vitamin C 34 mg/kg body mass/day. When the serum vitamin C levels were above 0,35 mg/100 ml the heart muscle lipoprotein lipase was repressed. Serum vitamin C ...

  15. Selection and optimization of extracellular lipase production using ...

    African Journals Online (AJOL)

    The aim of this study was to isolate and select lipase-producing microorganisms originated from different substrates, as well as to optimize the production of microbial lipase by submerged fermentation under different nutrient conditions. Of the 40 microorganisms isolated, 39 showed a halo around the colonies and 4 were ...

  16. Activity and stability of immobilized lipases in lipase-catalyzed modification of peanut oil

    Directory of Open Access Journals (Sweden)

    Soumanou Mohamed M.

    2004-11-01

    Full Text Available Fatty acid release during lipolysis of peanut oil using microbial free and immobilized lipases in aqueous media was developed. Immobilized lipase from Rhizomucor miehei (RML gave the best result from its ability to clive different fatty acids from peanut oil in such media. In organic solvent, interesterification of peanut oil with tricaprylin using immobilized lipases from RML, Chromobacterium viscosum (CVL and Candida rugosa (CRL was performed. The best substrate molar ratio of tricaprylin to peanut oil found was in the range 0.7 to 0.8. Using substrate molar ratio 0.7, high amount of structured triglyceride ST (about 35% MLM, 44% LML triglyceride fractions was obtained with lipase from RML in n-hexane. The results found in solvent free system were in some cases quite similar to that obtained in organic solvent. In nine successive batch interesterification in solvent free medium using immobilized RML and CRL, no significant loss of amount of both produced triacylglycerol fractions until batch 7 was observed with RML.

  17. Lipoprotein lipase and endothelial lipase in human testis and in germ cell neoplasms

    DEFF Research Database (Denmark)

    Nielsen, J E; Lindegaard, M L; Friis-Hansen, L

    2009-01-01

    . The results suggest that both EL and LPL participate in the supply of nutrients and steroidogenesis in the testes, and that especially EL may be important for the supply of cholesterol for testosterone production in the Leydig cells. The partial cellular separation of the expression of the two lipases...

  18. A robust and powerful two-step testing procedure for local ancestry adjusted allelic association analysis in admixed populations.

    Science.gov (United States)

    Duan, Qing; Xu, Zheng; Raffield, Laura M; Chang, Suhua; Wu, Di; Lange, Ethan M; Reiner, Alex P; Li, Yun

    2018-04-01

    Genetic association studies in admixed populations allow us to gain deeper understanding of the genetic architecture of human diseases and traits. However, population stratification, complicated linkage disequilibrium (LD) patterns, and the complex interplay of allelic and ancestry effects on phenotypic traits pose challenges in such analyses. These issues may lead to detecting spurious associations and/or result in reduced statistical power. Fortunately, if handled appropriately, these same challenges provide unique opportunities for gene mapping. To address these challenges and to take these opportunities, we propose a robust and powerful two-step testing procedure Local Ancestry Adjusted Allelic (LAAA) association. In the first step, LAAA robustly captures associations due to allelic effect, ancestry effect, and interaction effect, allowing detection of effect heterogeneity across ancestral populations. In the second step, LAAA identifies the source of association, namely allelic, ancestry, or the combination. By jointly modeling allele, local ancestry, and ancestry-specific allelic effects, LAAA is highly powerful in capturing the presence of interaction between ancestry and allele effect. We evaluated the validity and statistical power of LAAA through simulations over a broad spectrum of scenarios. We further illustrated its usefulness by application to the Candidate Gene Association Resource (CARe) African American participants for association with hemoglobin levels. We were able to replicate independent groups' previously identified loci that would have been missed in CARe without joint testing. Moreover, the loci, for which LAAA detected potential effect heterogeneity, were replicated among African Americans from the Women's Health Initiative study. LAAA is freely available at https://yunliweb.its.unc.edu/LAAA. © 2017 WILEY PERIODICALS, INC.

  19. The formation of FHA coating on biodegradable Mg-Zn-Zr alloy using a two-step chemical treatment method

    Science.gov (United States)

    Jiang, S. T.; Zhang, J.; Shun, S. Z.; Chen, M. F.

    2016-12-01

    To improve the corrosion resistance of the biomedical magnesium alloy, a two-step chemical treatment method has been employed to prepare an FHA coating on the alloy surface. Prior to forming an FHA layer, the samples of Mg-3 wt% Zn-0.5 wt% Zr alloy were soaked in HF with concentration of 20% (v/v) at 37 °C temperature for 2 h, and were then placed into an aqueous solution with 0.1 mol/L Ca(NO3).4H2O and 0.06 mol/L NH4H2PO4 at 90 °C to prepare the Ca-P coating. The concentrations of Mg2+, F- ions, and pH variation with immersing time in the solution were investigated to explore the growth mechanism of FHA. The surface morphologies and compositions of the coatings were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. The results showed that the alloy surface treated with acid formed a layer of MgF2 nanoparticles with a thickness of 0.7 μm. The corrosion resistance of coatings in SBF solution was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The results showed that the substrate with FHA coating had good corrosion resistance. After immersing into the calcium phosphate solution, some small spherical particles were first formed on the surface; these then cover the surface completely after 20 min. Some clusters consisting of needle-like crystal were observed in the spherical particles covering the surface, and the Ca/P ratio of the needle-like crystal was 1.46, clearly growing along the c axis preferred orientation growth. After immersion for 60 min, the FHA coating with completely uniform growth was obtained on the Mg-Zn-Zr alloy surface with its thickness reaching about 120 μm.

  20. A two-step sealing-and-reinforcement SU8 bonding paradigm for the fabrication of shallow microchannels

    Science.gov (United States)

    Mehboudi, Aryan; Yeom, Junghoon

    2018-03-01

    Adhesive bonding is a key technique to create microfluidic devices when two separate substrates are used to form microchannels. Among many adhesives explored in microchannel fabrication, SU8 has been widely used as an adhesive layer for sealing the microchannel sidewalls. The majority of the available SU8-based bonding methods, however, suffer from the difficulties associated with sealing of two important types of the microchannel architecture: (1) shallow microchannels with small patterns on a large area, and (2) microchannels with ultra-low aspect ratios (e.g. 6 mm in width and 2~μ m in height). In this paper, a new bonding paradigm based upon the low-temperature and low-pressure SU8 bonding, consisting of two steps of sealing using a thin-SU8-coated PET film and bonding reinforcement using a SU8-coated glass slide, is proposed to resolve the aforementioned difficulties. Since it does not need complicated instruments such as a wafer bonding machine and a lamination device, the developed bonding paradigm is convenient and economical. We successfully demonstrate the compatibility of the proposed bonding paradigm with the two microchannel fabrication approaches based on the glass wet etching and the SU8 photo-lithography, where small microchannels with the innermost surfaces fully made of SU8 are obtained. A theoretical model is employed to better investigate the flow characteristics and the structural behavior of the microchannel including the PET film deformation, strain and von Mises stress distributions, bonding strength, etc. Moreover, we demonstrate the fabrication of the multi-height deep-shallow microchannel sidewalls and their sealing using the SU8-coated PET film. Finally, as a proof-of-concept device, a microfluidic filter consisting of the double-height deep-shallow microchannel is fabricated for separation of 3 µm and 10 µm particles.