ANALYZING VERTICAL MARKET STRUCTURE AND ITS IMPLICATIONS FOR TRADE LIBERALIZATION AND MARKET ACCESS

International Relations/Trade,

Hydrophobic adsorption and covalent immobilization of Candida antarctica lipase B on mixed-function-grafted silica gel supports for continuous-flow biotransformations

Adsorption onto solid supports has proven to be an easy and effective way to improve the mechanical and catalytic properties of lipases. Covalent binding of lipases onto the support surface enhances the active lifetime of the immobilized biocatalysts. Our study indicates that mesoporous silica gels grafted with various functions are ideal supports for both adsorptive and covalent binding for lipase B from Candida antarctica (CaLB). Adsorption of CaLB on phenyl-functionalized silica gels improved in particular its specific activity, whereas adsorption on aminoalkyl-modified silica gels enabling covalent binding with the proper reagents resulted in only moderate specific activity. In addition, adsorption on silica gels modified by mixtures of phenyl- and aminoalkyl silanes significantly increased the productivity of CaLB. Furthermore, CaLB adsorbed onto a phenyl/aminoalkyl-modified surface and then treated with glutardialdehyde (GDA) as cross-linking agent provided a biocatalyst of enhanced durability. Adsorbed and cross-linked CaLB was resistant to detergent washing that would otherwise physically deactivate adsorbed CaLB preparations. The catalytic properties of our best immobilized CaLB variants, including temperature-dependent behavior were compared between 0 and 70 C with those of two commercial CaLB biocatalysts in the continuous-flow kinetic resolutions of racemic 1-phenylethanol rac-1a and 1-phenylethanamine rac-1b. © 2013 Elsevier Ltd

Probing Compressed Top Squarks at the LHC at 14 TeV

A feasibility study is presented for the search of the lightest top squark in a compressed scenario, where its mass is approximately equal to the sum of the masses of the top quark and the lightest neutralino. The study is performed in the final state of two b-jets, one lepton, large missing energy, and two high-$E_{\rm T}$ jets with large separation in pseudo-rapidity, in opposite hemispheres, and with large dijet mass. The LHC could discover compressed top squarks with mass up to approximately 340 GeV (390 GeV) with an integrated luminosity of 1000 ifb (3000 ifb).Comment: Version updated with major changes: (a) 3-body stop decay (to b+W+n1) analyzed for first time (b) systematics calculation and discussion significantly upgraded (c) new kinematic and mass reach plots for the 3-body decay scenario added (d) discussions clarified throughou

Probing Compressed Sleptons at the LHC using Vector Boson Fusion Processes

The vector boson fusion (VBF) topology at the Large Hadron Collider at 14 TeV provides an opportunity to search for new physics. A feasibility study for the search of sleptons in a compressed mass spectra scenario is presented in the final state of two jets, one or two low $p_{T}$ non-resonant leptons, and missing energy. The presence of the VBF tagged jets and missing energy are effective in reducing Standard Model backgrounds. Using smuon production with a mass difference between $\tilde{l}_{L}$ and $\tilde{\chi}_{1}^0$ of 5-15 GeV, the significance of observing the signal events is found to be $\sim$ 3-6$\sigma$ for $m_{\tilde{l}}$=115-135 GeV, considering an integrated luminosity of 3000 fb$^{-1}$.Comment: 6 pages, 1 figure, 3 tables; v3: Journal matched versio

Estimating Maximum Water Absorption of Wood Fiber/Polymer Fluff Composites

The objective of this study was to develop a model to estimate the maximum water absorption (MWA) of wood fiber/polymer fluff composites as a function of polymer fluff content and board density. Polymeric diphenylmethane diisocyanate (PMDI) resin bonded dry-process wood fiber/polymer fluff composites were used in this study. Six polymer fluff contents (0, 15, 30, 45, 60, and 100%) and four target oven-dry board densities in the range of 0.50-1.00 g/cm3 were studied. A water immersion test was conducted on these boards. The effect of irreversible thickness swelling after water immersion (TSi) on the estimation of the maximum water absorption was evaluated. It was shown that the irreversible thickness swelling had a quadratic relationship with polymer fluff content and a linear relationship with oven-dry board density. The TSi of the composites used in this study was in the range of only 0.04-4.20%, which was negligible in the estimation of maximum water absorption. The prediction of maximum water absorption from the MWA model developed in this study was over 95% accuracy for most of the specimens. The maximum water absorption had a linear relationship with the polymer fluff content and a reciprocal relationship with board density

Microtension Test Method for Measuring Tensile Properties of Individual Cellulosic Fibers

A microtension testing system was devised to measure mechanical properties of individual cellulosic fibers. To avoid specimen gripping and to enhance fiber alignment during testing, a self-aligning ball and socket gripping assembly was used in the microtensile tester design. A resolution of 0.098 mN was obtained for the tensile load measurement with this microtensile tester. Fiber strain was determined from high-precision stepper motor movement with 0.078-μm resolution or by in situ video photography. Cross-sectional areas of a single fiber cell wall were measured with a confocal laser scanning microscope. Results obtained from this system indicated a linear stress-strain curve until fatal failure for mature latewood fibers, whereas juvenile latewood fibers displayed curvilinear stress-strain relationships. Average values of tensile strength, tensile modulus, and elongation at break were 1258 MPa, 19.9 GPa, and 6.6% for mature latewood fiber and 558 MPa, 8.5 GPa, and 9.9% for juvenile latewood fiber, respectively. These values agreed with published data. The preliminary test indicated the usefulness of the integrated environmental chamber for investigating moisture effect on fiber engineering properties, but further investigation is needed to obtain statistically significant data

Investigation of OSB Thickness-Swell Based on a 3d Density Distribution. Part I. The Finite Element Model

A finite element model was developed for predicting thickness-swell of oriented strandboard. The model accounts for both vertical and horizontal density variations of the board, or the three-dimensional density distribution. Density variation, resulting from manufacturing processes such as strand orientation and pressing cycles, affects the uniformity of thickness-swell in OSB. The model uses nonlinear constitutive behavior in the through-the-thickness direction. Moisture changes were modeled using transient moisture transfer equations and coupled moisture-density-stress-strain relations. The model was used to predict thickness-swell during a 24-h soak test. The model was able to predict average thicknes-swell of commercial panels with an acceptable error, generally less than 10%

Progress in the development and application of computational methods for probabilistic protein design

Proteins exhibit a wide range of physical and chemical properties, including highly selective molecular recognition and catalysis, and are also key components in biological metabolic, catabolic, and signaling pathways. Given that proteins are well-structured and can now be rapidly synthesized, they are excellent targets for engineering of both molecular structure and biological function. Computational analysis of the protein design problem allows scientists to explore sequence space and systematically discover novel protein molecules. Nonetheless, the complexity of proteins, the subtlety of the determinants of folding, and the exponentially large number of possible sequences impede the search for peptide sequences compatible with a desired structure and function. Directed search algorithms, which identify directly a small number of sequences, have achieved some success in identifying sequences with desired structures and functions. Alternatively, one can adopt a probabilistic approach. Instead of a finite number of sequences, such calculations result in a probabilistic description of the sequence ensemble. In particular, by casting the formalism in the language of statistical mechanics, the site-specific amino acid probabilities of sequences compatible with a target structure may be readily identified. The computational probabilities are well suited for both de novo protein design of particular sequences as well as combinatorial, library-based protein engineering. The computed site-specific amino acid profile may be converted to a nucleotide base distribution to allow assembly of a partially randomized gene library. The ability to synthesize readily such degenerate oligonucleotide sequences according to the prescribed distribution is key to constructing a biased peptide library genuinely reflective of the computational design. Herein we illustrate how a standard DNA synthesizer can be used with only a slight modification to the synthesis protocol to generate a pool of degenerate DNA sequences, which encodes a predetermined amino acid distribution with high fidelity