Distributed Path-Based Inference in Semantic Networks

This paper presents the task model, instruction set, reasoning scheme, software infrastructure, as well as the experimental results, of a new distributed semantic network system. Unlike the synchronous and static marker passing algorithm previously used for parallel semantic network design, our system operates asynchronously, supporting knowledge sharing, dynamic load balancing and duplicate checking. To better the performance in distributed environments, the system has two collaborating components: the slave module, which performs task execution; and the host module, which interacts with the user and processes the information for the slaves. Our current implementation focuses on path-based knowledge inferences, using ANSI C and the MPICH-G2 with flex lexical analyzer and the yacc parser generator. Tests of individual components have been performed on a SUN multiprocessor server. The experiments demonstrate promising speedups.     

Thermoplastic elastomer blend based on EMA and NBR; optimization of process parameters

EMA–NBR has been explored to be a potential thermoplastic elastomer blend having good thermal stability as well as oil resistance property. The present investigation reports the optimization of process parameters for the novel polymer blends based on poly(ethylene-co-methyl acrylate) (EMA) and poly(acrylonitrile-co-butadiene) rubber (NBR) with criteria based on the statistical design of experiment (Taguchi L9 orthogonal array). In this case, the polymer blends were prepared by changing the polymer blending conditions such as mixing temperature, mixing time and rotor speed as per Taguchi's L9 orthogonal array. Optimization of the process parameters was carried out based on the physicomechanical properties such as tensile strength, elongation at break, hardness, and tensile impact strength of the resulting EMA/NBR blend. Each processing parameter has been optimized from the experimental data, which are converted into signal-to-noise ratio. The standard statistical technique of analysis of variance result was used to evaluate the proportional role of the different control variables. It has been found that the mixing temperature play very significant role trailed by rotor speed and mixing time in controlling droplet matrix morphology of the EMA/NBR blends. Predominantly, these factors affect the size of the NBR domain and its distribution in the EMA matrix, which in turn have a notable contribution to the physicomechanical properties of the blends. By the optimization of processing conditions, the NBR matrix domain size greatly decreases, leading to significant improvement in physicomechanical properties of the EMA/NBR blends. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48900.     

The Effect of Melt Ultrasound Treatment on the Microstructure and Age Hardenability of Al-4 Wt Pct Cu/TiC Composite

Metallurgical and Materials Transactions B - In the present work, Al-4 wt pct Cu/TiC composite was synthesized by the molten salt route that contains submicron-sized TiC particles in the Al-4 wt...     

Development of cold work tool steel based-MMC coating using HVOF spraying and its HIP densification behaviour

The aim of the present study is to develop a Fe-based metal matrix composite (MMC) coating using high velocity oxy-fuel spraying (HVOF) process. A ledeburitic high alloyed cold work tool steel (X220CrVMo13-4) and NbC with an average size of 2 µm at different volume fractions have been considered as metal matrix and hard particles respectively. MMC coatings were deposited on austenitic stainless substrates and the coatings were subsequently densified by hot isostatic pressing (HIP) with and without encapsulation. Microstructural analysis of the as-sprayed and HIPed coatings were characterized by SEM and XRD methods. Results showed that the feedstock preparation involving fine NbC was an influencing factor on the coating deposition. A relatively homogeneous dispersion of fine NbC up to 30 vol.% in cold work tool steel matrix was possible using optimized HVOF spraying. Besides, HVOF spraying and its subsequent HIP treatment induced significant microstructural and phase changes in the MMC coatings. The study showed the potential of HVOF spraying for the development of steel based MMC coatings and its subsequent densification can be achieved by HIP process with and without encapsulation.     

Metal oxide-assisted chemical synthesis of poly(α-naphthylamine) and characterizations

α-Naphthylamine (NA) was chemically polymerized using peroxy disulfate (PDS) as a chemical initiator under inert atmosphere at 45 °C with vigorous stirring under various experimental conditions such as different concentrations of NA, PDS and different % weight of nanosized metal oxides like Sb₂O₃, CrO₃, V₂O₅, Al₂O₃, As₂O₃ and ammonium heptamolybdate (AHM). Chemical kinetics inferred that rate of polymerization (R _p) is 1.75 order of reaction with [NA] and 1.0 with [PDS]. FTIR spectroscopy confirmed that both benzenoid and quinonoid rings built up the structure of poly(α-naphthylamine) (PNA). Added metal oxides influenced the R _p, char forming capability of PNA and conductivity too through their surface catalytic effect. AFM confirmed the presence of nanosized materials in the polymer–nanocomposite structure. HRTEM was used to confirm the nanosize of metal oxides and the intercalation of PNA chains into the basal spacing of metal oxides.     

Ionic conductivity and Raman investigations on the phase transformations of Na4P2O7

The ionic conductivity and thermo-Raman spectra of anhydrous sodium pyrophosphate Na₄P₂O₇ were measured dynamically in the temperature range from 25 to 600 °C with a heating rate of 2 °C min⁻¹ to understand the structural evolution and phase transformation involved. The DSC thermogram was also measured in the same thermal process for the phase transformation investigation. The spectral variations observed in the thermo-Raman investigation indicated the transformation of Na₄P₂O₇ from low temperature phase () to high temperature phase () proceeded through pre-transitional region from 75 to 410 °C before the major orientational disorder at 420 °C and minor structural modifications at 511, 540 and 560 °C. The activation energies and enthalpies of the proposed phase transformations were determined. The possible mechanism for temperature dependent conductivity in Na₄P₂O₇ was discussed with the available data.     

Parallel pattern identification in biological sequences on clusters

Tandem repeats are ubiquitous sequence features in both prokaryotic and eukaryotic genomes. They are known to cause several inherited neurological diseases in humans. Identifying these patterns is a highly computation-intensive process. Previous parallel implementations use straightforward domain decomposition based on existing sequential algorithms and rely on parallel machines with low-latency interconnection network and fast hardware support for processor synchronization. Our research exploits the superior cost effectiveness and flexibility achieved through low-cost clusters to speed up biological computations by designing communication-efficient parallel algorithms for pattern identification. This paper presents a low communication-overhead parallel algorithm for pattern identification in biological sequences. Given a biological sequence of length n and a pattern of length m, we conclude an algorithm with five computation/communication phases, each requiring O(n) computation time and only O(p) message units. The low communication overhead of the algorithm is essential in achieving reasonable speedups on clusters, where the interprocessor communication latency is usually higher.     

Designing biological apatite suitable for neomycin delivery

Bovine-derived biological apatite has a long history for use in human health care as bone substitute. This article reports an elegant method of designing bovine-derived hydroxyapatite (BHA) blocks suitable for drug delivery. Neomycin sulphate (NS) was selected as a model drug and its loading and release studies were performed under in-vitro physiological conditions. The results indicate that phase purity and structural integrity of the BHA are retained even after entrapment of drug molecules. It was noticed that the rate of neomycin delivery was directly proportional to the porosity of the BHA blocks. The in-vitro release studies suggest that BHA may be used as a good carrier system for neomycin delivery.     

Assessment of Amyloid Forming Tendency of Peptide Sequences from Amyloid Beta and Tau Proteins Using Force-Field,Semi-Empirical,and Density Functional Theory Calculations

A wide variety of neurodegenerative diseases are characterized by the accumulation of protein aggregates in intraneuronal or extraneuronal brain regions. In Alzheimer’s disease (AD), the extracellular aggregates originate from amyloid-β proteins, while the intracellular aggregates are formed from microtubule-binding tau proteins. The amyloid forming peptide sequences in the amyloid-β peptides and tau proteins are responsible for aggregate formation. Experimental studies have until the date reported many of such amyloid forming peptide sequences in different proteins, however, there is still limited molecular level understanding about their tendency to form aggregates. In this study, we employed umbrella sampling simulations and subsequent electronic structure theory calculations in order to estimate the energy profiles for interconversion of the helix to β-sheet like secondary structures of sequences from amyloid-β protein (KLVFFA) and tau protein (QVEVKSEKLD and VQIVYKPVD). The study also included a poly-alanine sequence as a reference system. The calculated force-field based free energy profiles predicted a flat minimum for monomers of sequences from amyloid and tau proteins corresponding to an α-helix like secondary structure. For the parallel and anti-parallel dimer of KLVFFA, double well potentials were obtained with the minima corresponding to α-helix and β-sheet like secondary structures. A similar double well-like potential has been found for dimeric forms for the sequences from tau fibril. Complementary semi-empirical and density functional theory calculations displayed similar trends, validating the force-field based free energy profiles obtained for these systems.