Structure–function analysis of D9N and N291S mutations in human lipoprotein lipase using molecular modelling

Lipoprotein lipase (LPL) plays a central role in lipid metabolism. The D9N and N291S mutations in the LPL gene are associated with elevated triglyceride and decreased HDL-cholesterol levels. Published in vitro expression studies suggest that these two mutations are associated with reduced LPL enzymatic activity. We sought to gain further insight on the impact of these two mutations on the LPL structure and function by molecular modelling techniques. Homology modelling was used to develop a three-dimensional (3D) structure of LPL from human pancreatic lipase. Two separate LPL models for the D9N and N291S substitutions were constructed and compared with the wild type LPL for differences in hydrophobicity, atomic burial, hydrogen bond pattern, and atomic mobility. In comparison to the wild type model, the 9N model was associated with significantly increased atomic mobility of its neighboring residues, but the catalytic site was not affected. The region near residue 9 in the upper part of the N-domain was considered a candidate site for protein–protein interaction. In the N291S model, alterations in H-bonds and constrained atomic mobility were among conformational changes in the region where the substitution had occurred. These are hypothesized to cause an increase in the rate of dissociation in LPL dimerization, subsequently affecting the LPL enzymatic activity. We also modelled the C-domain of apoCII, the obligatory cofactor of LPL, from 2D NMR data and docked the model with LPL to explore their interaction site. These docking experiments suggest that the C-domain of apoCII interacts with the interface of N- and C-domains of LPL and part of the lid structure that covers the catalytic site. In summary, we provide molecular modelling data on two well-known mutations in the LPL gene to help explain the published in vitro expression findings and propose a possible LPL-apoCII interaction site. Our data indicate that molecular modelling of LPL mutations could provide a valuable tool to understand the effects of a mutation on the structure–function of this important enzyme.     

Learning Translation Templates from Bilingual Translation Examples

A mechanism for learning lexical correspondences between two languages from sets of translated sentence pairs is presented. These lexical level correspondences are learned using analogical reasoning between two translation examples. Given two translation examples, the similar parts of the sentences in the source language must correspond to the similar parts of the sentences in the target language. Similarly, the different parts must correspond to the respective parts in the translated sentences. The correspondences between similarities and between differences are learned in the form of translation templates. A translation template is a generalized translation exemplar pair where some components are generalized by replacing them with variables in both sentences and establishing bindings between these variables. The learned translation templates are obtained by replacing differences or similarities by variables. This approach has been implemented and tested on a set of sample training datasets and produced promising results for further investigation.     

Supporting ranking queries on uncertain and incomplete data

Large databases with uncertain information are becoming more common in many applications including data integration, location tracking, and Web search. In these applications, ranking records with uncertain attributes introduces new problems that are fundamentally different from conventional ranking. Specifically, uncertainty in records’ scores induces a partial order over records, as opposed to the total order that is assumed in the conventional ranking settings. In this paper, we present a new probabilistic model, based on partial orders, to encapsulate the space of possible rankings originating from score uncertainty. Under this model, we formulate several ranking query types with different semantics. We describe and analyze a set of efficient query evaluation algorithms. We show that our techniques can be used to solve the problem of rank aggregation in partial orders under two widely adopted distance metrics. In addition, we design sampling techniques based on Markov chains to compute approximate query answers. Our experimental evaluation uses both real and synthetic data. The experimental study demonstrates the efficiency and effectiveness of our techniques under various configurations.     

Goal-directed aimed movements with path obstructions

Studies are reported in which participants moved from a starting position to a final target, but moved around obstacles that prevented a direct path being taken. Seven experiments are reported in which subjects made multiple-component movements, defined by changes in the direction of movement, but without intervening targets (or stopping points) between components. It was found that components of movement time did not interact, contrary to the results of Gan and Hoffmann (1988b) for cases where there was an intervening target, and that component times could be added. For ballistic components, the time for the movement was linearly related to the square root of the total amplitude of movement; for components that were visually controlled, the time was related to Fitts' Index of Difficulty based on the total amplitude of movement and the final target size. Results are compared to data for movements with intervening targets, where the movement integration hypothesis is valid. PRACTITIONER SUMMARY: Many movements, particularly to inaccessible places, cannot be made directly, but must be made about obstacles in the path. This research shows how times for these movements can be quantified in terms of the direct path length and the size and location of the obstacles.     

Forming Antifouling Organic Multilayers on Porous Silicon Rugate Filters Towards In Vivo/Ex Vivo Biophotonic Devices

We describe the development and optimization of porous silicon photonic crystal surface chemistry towards implantable optical devices. Porous silicon rugate filters were prepared to obtain a narrow linewidth reflectivity peak in the near‐infrared (700–1000 nm) with low background reflectivity elsewhere. The morphology of the mesoporous structures (pore diameter < 50 nm) was such that only small proteins could infiltrate the pores whereas larger proteins were excluded. To provide stability in biological media, we established an approach to build organic multilayers containing hexa(ethylene oxide) moieties in porous silicon. The optical changes associated with organic derivatization were monitored concurrently with FTIR characterization. Furthermore, the antifouling capability of our chemical strategy is assessed and the penetration of different sized proteins into the structure was determined. The structural stability in biological environments was evaluated by incubation in human blood plasma over time while monitoring the optical signature of the photonic crystal.     

Linear stability analysis of MHD flow of micropolar fluid with thermal radiation and convective boundary condition: Exact solution

Magnetohydrodynamic (MHD) flow of micropolar fluid by including the thermal radiation and convective condition on a shrinking surface in the presence of mass suction effects has been investigated. The momentum, angular momentum and energy equations, and the solutions of these equations are valid for whole Navier stokes, and microrotational and energy equations have been solved exactly. We obtain the solution in the form of an incomplete γ function for the energy equation. The results reveal that dual solutions exist for certain domains of different physical parameters. Furthermore, high suction produces the high effect of drag force, and as a result, coefficient of skin friction increases in the first solution. Stability analysis has been performed and determined that the first solution is more stable.     

Co‐poly(vinyl chloride‐vinyl acetate‐vinyl alcohol)‐silica nanocomposites from sol–gel process: Morphological,mechanical, and thermal investigations

Organic–inorganic nanocomposites consisting of co‐poly(vinyl chloride‐vinyl acetate‐vinyl alcohol) and silica were prepared via sol–gel process. Two types of hybrids were prepared, one in which interactions between hydroxyl group present in the copolymer chain and silanol groups of silica network were developed. In the second set, extensive chemical bonding between the phases was achieved through the reaction of hydroxyl groups on the copolymer chains with 3‐isocyanatopropyltriethoxysilane (ICTS). Hydrolysis and condensation of tetraethoxysilane and pendant ethoxy groups on the chain yielded inorganic network structure. Mechanical and thermal behaviors of the hybrid films were studied. Increase in Young's modulus, tensile strength, and toughness was observed up to 2.5 wt % silica content relative to the neat copolymer. The system in which ICTS was employed as binding agent, the tensile strength and toughness of hybrid films increased significantly as compared to the pure copolymer. Thermogravimetric analysis showed that these nanocomposite materials were stable up to 250°C. The glass transition temperature increases up to 2.5 wt % addition of silica in both the systems. Field emission scanning electron microscope results revealed uniform distribution of silica in the copolymer matrix. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Inducing translation templates with type constraints

This paper presents a generalization technique that induces translation templates from a given set of translation examples by replacing differing parts in the examples with typed variables. Since the type of each variable is inferred during the learning process, each induced template is also associated with a set of type constraints. The type constraints that are associated with a translation template restrict the usage of the translation template in certain contexts in order to avoid some of the wrong translations. The types of variables are induced using type lattices designed for both the source and target languages. The proposed generalization technique has been implemented as a part of an example-based machine translation system.     

An efficient technique for integrating voice and data in wireless communications with a cellular structured environment

The need for efficient radio channel utilization in an environment of dispersed roaming terminals with adverse characterization, has encouraged new areas of research in mobile communication system. It is therefore in this vein that we propose a new multiple access technique that improves system throughput. In this paper, the performance analysis of a wireless communication system capable of integrating voice and data efficiently over radio frequency channels through the proposed scheme, multiple access with reservation after contention (MARC) is presented. Integrating packets of voice and data information onto a common channel is accomplished by placing the data within the silence gaps of the speed conversation, but after a successful contention and upon slot assignment. The scheme employs contention for uplink access to the radio channel via the base station, thus providing a means of control access.     

Facile synthesis of titanium dioxide‐cadmium sulfide nanocomposite using pulsed laser ablation in liquid and its performance in photovoltaic and photocatalytic applications

Narrow band gap semiconductors like cadmium sulfide (CdS) are being applied as an agent to reduce the band gap of metal oxide semiconductors like titanium dioxide (TiO₂). In order to obtain a TiO₂/CdS nanocomposite with reduced electron‐hole recombination and improved stability, we coupled 10%, 20%, and 40% by weight of CdS with TiO₂ in this work using pulsed laser ablation in liquid technique. Here, 532 nm wavelength generated from neodymium‐doped yttrium aluminum garnet laser was directed into the TiO₂/CdS mixture prepared in a colloid form to produce the TiO₂/CdS nanocomposites. The effect of the CdS concentration on the performance of the obtained nanocomposite in a dye‐sensitized solar cell and photocatalytic degradation of methyl orange in water was studied in detail. However, the nanocomposite with 10% percentage weight of CdS in anatase TiO₂ showed the best performance as compared with pure TiO₂, and the photoconversion efficiency of the dye‐sensitized solar cell was improved from 0.6% to 4.3%, while the percentage of methyl orange degraded was enhanced from 58% to 82% after 36 min irradiation using ultraviolet–visible light. This improvement in photovoltaic and photodegradation properties is due to limited electron hole recombination rate, higher conduction of charge carriers, their longer lifetime during the photocatalytic process, improved ultraviolet–visible light activity, reduced photocorrosion, and improved pore size. Copyright © 2017 John Wiley & Sons, Ltd.