39 research outputs found

    ENTRAPMENT OF FLUORESCENT E. COLI CELLS IN ALGINATE GEL

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    By this experiment we will demonstrate the possibility to obtain genetically modifiedmicrobial strains that can be used as markers in different studies. The traittransferred in this study is the fluorescence in UV light expressed by a gene isolatedfrom jellyfish. This gene was insered into a plasmid carrying ampiciline resistanceand in the operon for arabinose fermentation. The plasmid was called pGLO. E coliHB101 K-12, ampicillin resistant colonies has been obtained. The colonies on theLB/amp/ara plate fluoresce green under UV light and the transformed colonies cangrow on ampicillin. Transformation efficiency = 362 transformed colonies/ ÎĽg DNA.The cells where immobilized by entrapment in alginate gel to study the phenomenoninvolved in cells immobilization. After immobilization in alginate gel, 5x104 cells ofE. coli pGLO / capsule and 1,4 x 105 cells of E. coli HB101/capsule has been found.Fluorescent microscopy revealed the presence of pGLO carrying cells into thecapsules. After cultivation of alginate capsules containing E. coli in LB broth, andfluorescent microscopy of the capsule sections, several observations of thephenomenon involved in continuous fermentation using biocatalysts in has beenmade. These cells grow and migrate to the cortical part of the matrix where they areimmobilized

    ENZYMATIC HYDROLYSIS OF AGRICULTURAL LIGNOCELLULOSIC BIOMASS

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    The yield, productivity and cost for the enzymatic hydrolysis of cellulose to glucoseare crucial for the production of second generation ethanol. In the first study wehave evaluated the activity of several commercial cellulolytic enzymes and a crudeextract of a local strain of Trichoderma viride. The load used was 15 U ofcellulase/gram cellulose and 90 U of cellobiase/gram cellulose. The hydrolysis wascarried out at 50oC and pH 4,8 for 96 hours. The best cellulose hydrolysis yield of58% was obtained with the cocktail formed of crude cellulases from T. virideCMIT3.5 combined with Novozyme 188. This cocktail was used in the second study,when alkaline-steam pretreated wheat straw and corn stover where hydrolyzed at pH4,8 for 96 hours. The temperature was set at 50oC and 40oC. The hydrolysis at lowertemperature was tested for a future experiment of simultaneous hydrolysis andfermentation. An enzymatic assay using glucose-6-phosphate dehydrogenase wasused to determine exclusively glucose, instead of wide-range sugar DNS assay.Reporting to 100 grams of wet pretreated biomass, the following results wereobtained: 14.4 g% glucose for corn stover at 50oC and 13,0 g% at 40oC; 13,1 g%glucose for wheat straw at 50oC and 10.3 g% at 40oC. Considering that wheat strawcontain 36.6% glucose-based carbohydrates, the hydrolysis yields are between39.3% and 28.1%. Further studies, concerning the optimal parameters for cellulasecocktail will be made

    Stock markets and effective exchange rates in European countries: threshold cointegration findings

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    © 2015, Eurasia Business and Economics Society. The nexus between stock markets and exchange rates is examined in the case of eight European countries. The sample consists of four economies with national currencies and four that have adopted the euro. Thus, if differences between the two groups in the relationship governing the two markets exist, they will be unveiled. To this effect, a threshold cointegration methodology is adopted that allows for more reliable inferences to be drawn for both the short and long run nexus between the two markets. Monthly data is used covering the period 01/2000–12/2014. The findings reported herein offer support in favor of the portfolio approach thesis over the recent economic crisis period, but this finding is not the case for the entire sample. Bidirectional causality is found for Norway and the UK, pointing to a currency effect on stock markets. In view of the findings reported herein, policies aiming at reducing uncertainty in the stock markets can exert beneficial effects on currency markets

    Compact Phase Shifting Cell Based on Micro-Strip Slow Wave Lines

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    International audienceThis paper addresses the design, the simulations and the measurements results of an original and compact MMIC phase shifter using micro-strip slow wave lines implemented in a 0.25µm SiGe BiCMOS process for Ku-band applications. The simulations and the experimental results demonstrate interesting performances compared to classical phase shifter topologies

    Compact phase shifting cell based on micro-strip slow wave lines Kapton flexible technology for V-band applications

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    International audienceThis paper addresses the design, thesimulations and the measurements results of an original andcompact MMIC phase shifter using micro-strip slow wavelines implemented in a 0.25ÎĽm SiGe BiCMOS process forKu-band applications. The simulations and theexperimental results demonstrate interesting performancescompared to classical phase shifter topologies

    Experimental, analytical and numerical investigation of non-linearity of SOI diode temperature sensors at extreme temperatures

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    International audienceThis paper presents the performance of a silicon-on-insulator (SOI) p+/p-well/n+ diode temperature sensor, which can operate in an extremely wide temperature range of 80 K to 1050 K. The thermodiode is placed underneath a tungsten micro-heater which is embedded in a thin dielectric membrane, obtained with a post-CMOS deep reactive ion etching process. Analytical and numerical models are used to support experimental findings. Non-linearity, sensitivity and methods for their reduction and enhancement, respectively, are investigated in detail

    Experimental, analytical and numerical investigation of non-linearity of SOI diode temperature sensors at extreme temperatures

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    This paper presents the performance of a silicon-on-insulator (SOI) p+/p-well/n+ diode temperature sensor, which can operate in an extremely wide temperature range of 80 K to 1050 K. The thermodiode is placed underneath a tungsten micro-heater which is embedded in a thin dielectric membrane, obtained with a post-CMOS deep reactive ion etching process. Analytical and numerical models are used to support experimental findings. Non-linearity, sensitivity and methods for their reduction and enhancement, respectively, are investigated in detail
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