Finding structure in noisy text: topic classification and unsupervised clustering

This paper addresses two types of classification of noisy, unstructured text such as newsgroup messages: (1) spotting messages containing topics of interest, and (2) automatic conceptual organization of messages without prior knowledge of topics of interest. In addition to applying our hidden Markov model methodology to spotting topics of interest in newsgroup messages, we present a robust methodology for rejecting messages which are off-topic. We describe a novel approach for automatically organizing a large, unstructured collection of messages. The approach applies an unsupervised topic clustering procedure to generate a hierarchical tree of topics.     

A scatter search approach for general flowshop scheduling problem

This paper proposes a new evolutionary technique called scatter search for scheduling problems of a general flow-shop. Scatter search (SS) is applied to this problem as it is able to provide a wide exploration of the search space through intensification and diversification. In addition it has a unifying principle for joining solutions which exploit the adaptive memory principle to avoid generating or incorporating duplicate solutions at various stages of the problem. This methodology provides substantially better results than the Tabu search approach of Nowicki and Smutnicki (Manage Sci 42(6):797–813, 1996) and Jain and Meeran (Comput Oper Res 29:1873–1901, 2002). The proposed framework achieves an average deviation of 14.25% from the lower bound solution of benchmark problems of Demirkol et al. (Eur J Oper Res 109(1):137–141, 1998), while the scatter search technique gives the best solutions for 32 of 40 of their benchmark problems.     

Tape casting of nickel manganite NTC ceramics for chip thermistors

Tape casting is a reliable route for mass production of precise miniature NTC chip sensors. The present paper describes the development work in tape casting of nickel manganite based NTC formulations. The most suitable dispersion condition of the powder in MEK–ethanol solvent system was determined by rheological and sedimentation studies. The optimized slurry composition for obtaining defect-free tapes was achieved by controlling the amounts of organic additives. The sintered chip samples exhibited 98% theoretical density with an over all shrinkage of 17%.     

Effects of Ionizing Radiation on Microbial Decontamination, Phenolic Contents, and Antioxidant Properties of Triphala

ABSTRACT:  Triphala, a mixture of Emblica officinalis , Terminalia chebula , and Terminalia bellirica , containing ingredients from plant origin, is often prone to microbial contamination. A high level of microbial contamination was observed in Triphala samples obtained from different sources. On gamma radiation processing, a sharp decline in log CFU was observed with increasing radiation dose and a complete decontamination at 5 kGy. Average D 10 value for total aerobic and fungal counts were observed to be 0.55 ± 0.073 kGy and 0.94 ± 0.043 kGy, respectively. Water extracts of irradiated samples showed linearly increasing concentration of gallic acid (3.3 to 4.5 times), total phenolic contents (2.16 to 2.87 times), and antioxidant properties with increasing radiation dose up to 25 kGy. The increase could be attributed to easy release of active ingredients from their radiation degraded complex forms. Aflatoxin B₁ and ochratoxin could not be detected in the samples. Gamma-radiation dose up to 5 kGy could be safely used to hygienize Triphala.     

An investigation into the effect of Cs promotion on the catalytic activity of NiO in the direct decomposition of N2O

A series of Cs promoted NiO catalysts have been prepared and tested for direct decomposition of N₂O. These catalysts are characterized by BET surface area, X-ray diffraction (XRD), temperature programmed reduction (TPR), temperature programmed desorption of N₂O (TPD-N₂O) and X-ray photo electron spectroscopy (XPS). The Cs promoted NiO catalysts exhibit higher activity for the decomposition of N₂O compared to bulk NiO. The catalyst with Cs/Ni ratio of 0.1 showed highest activity. The enhancement in catalytic activity of the Cs promoted catalysts is attributed to the change in the electronic properties of NiO. The characterization techniques suggest weakening of Ni–O bond thereby the desorption of oxygen becomes more facile during the reaction. The Cs promoted NiO catalyst is effective at low reaction temperature and also in the presence of oxygen and steam in the feed stream. IICT Communication No: 070523.     

Studies of guar gum compression-coated 5-aminosalicylic acid tablets for colon-specific drug delivery

The aim of this study was to develop colon-specific delivery systems for 5-aminosalicylic acid (5-ASA) using guar gum as a carrier. Core tablets containing 5-ASA were prepared by wet granulation with starch paste and were compression coated with coating formulations containing different quantities of guar gum (300, 200, 150, and 125 mg). In vitro drug release studies were carried out in simulated gastric and intestinal fluids and in pH 6.8 buffer containing rat cecal contents. The application of 175 mg of coating formulation containing 150 mg of guar gum over 5-ASA core tablets resulted in the release of less than 2% drug in simulated gastric and intestinal fluids and about 93% of 5-ASA in pH 6.8 buffer containing rat cecal contents. Differential scanning calorimetric (DSC) studies showed the absence of any interaction between 5-ASA and the excipients on storage at 45°C for 12 weeks. The study confirmed that selective delivery of 5-ASA to the colon can be achieved using guar gum as a carrier in the form of a compression coating over the drug core.     

Efficient computation of frequency response of digital networks

A major requirement in the analysis of multi-input-multi-output digital networks is to compute the frequency response at a large number of points from a knowledge of the graph of a network with specified input and output nodes. Though the usual method of analysis by solving linear equations is more efficient than matrix inversion, solution of linear equations at each frequency may still require a large amount of computation. A more efficient method is to determine the poles and zeros of the desired system function and then calculate the frequency response from them. Though poles of the system function could be readily identified as contained in the eigenvalues of the state matrix of the network, difficulty is seen to arise in the determination of zeros which can not so easily be calculated. A simple and efficient method is proposed reducing the determination of zeros to a standard eigenvalue problem.     

Nanospikes on Customized 3D-Printed Titanium Implant Surface Inhibits Bacterial Colonization

Additive manufacturing has opened the door to patient-tailored orthopedic implants, which can significantly minimize implant failures associated with prosthesis-to-bone mismatch. Success of an implant also depends on the choice of implant materials, effective osseointegration, implant quality, and the mechanical properties together with its capability to limit infection due to bacterial contamination. Herein, nanospikes are created on 3D-printed titanium-alloyed implant surfaces, which can kill bacteria to minimize any implant-associated infections. For the first time, orthopedic implants with a fracture to the proximal phalanx are fabricated using selective laser melting (SLM) followed by a heat-treatment step and the hydrothermal process. It is showed in the results that by optimizing SLM parameters, dimensionally consistent parts can be produced and tensile properties of the 3D-printed implants can be significantly improved via a simple cyclic heat-treatment process compared to the traditionally manufactured implants. Nanospikes similar to those present on dragonfly wings fabricated on 3D-printed implants surface are able to kill above 90% of adhering bacteria by rupturing the membranes upon contact. These results indicate that fabrication of patient-specific 3D-printed implants with inherent bactericidal properties has the potential to eliminate postsurgical infections and possible implant failures.     

Structural,thermal, dielectric,nonlinear optical properties and DFT investigations of a novel material 2-(6-chloropyridin-3-yl)-N'-(2,3-dihydro-1,4-benzodioxin-6-ylmethylidene)acetohydrazide for optoelectronic applications

A new organic nonlinear optical (NLO) material 2-(6-chloropyridin-3-yl)-N'-(2,3-dihydro-1,4-benzodioxin-6-ylmethylidene)acetohydrazide (CDA) has been synthesized by reflux method. Single crystals were grown by slow evaporation technique and the crystal structure was elucidated by single crystal X-ray diffraction method. Density functional theory (DFT) calculations at B3LYP/6–31+?+?G(d, p) basis set was used to predict the molecular geometry and were carried out further to comprehend the electronic structure, vibrational spectra, natural bonding orbitals (NBO), frontier molecular orbitals (FMO) and molecular electrostatic potential (MEP). An optical transparency at the cut-off wavelength of 355 nm was determined by UV–Vis–NIR spectroscopy. Thermal behavior of CDA was studied by TGA/DTA analysis. The dielectric constant (ε), dielectric loss (tan δ) and AC conductivity as a function of frequency and temperature was studied. Second Harmonic Generation (SHG) efficiency of the CDA was determined using Kurtz and Perry powder technique and was 0.5 times greater than that of the KDP crystal. The third-order nonlinear optical properties were investigated in solution by Z-scan technique using a continuous wave (CW) DPSS laser at the wavelength of 532 nm. The title compound exhibited significant two-photon absorption (β?=?2.228?×?10–4 cm W^?1), nonlinear refraction (n₂?=?1.095?×?10–8 cm² W^?1) and optical limiting (OL threshold?=?2.511?×?103 W cm^?2) under the CW regime. The nonlinear optical parameters were calculated using time-dependent Hartree–Fock (TDHF) method. The overall obtained results suggested that the studied CDA molecule could be a potential NLO material for frequency generator, optical limiters and optical switching applications.