Surface properties of CaNi5 hydrogen storage alloy

The Ca 2p, Ni 2p and O 1s emissions of the air-exposed sample of CaNi₅ indicate that all the calcium and most of the nickel are present in the oxidized state. Interestingly, it is observed that all the peaks are shifted by 3 to 4 eV towards higher binding energy values. This observation has been attributed to the presence of insulating oxide phases leading to partial charging of the sample during the experiment. Depth profiling by argon-ion sputtering removes the insulating oxide species and the sample etched for 7300 sec shows the presence of metallic nickel and mostly metallic calcium. XPS analysis indicates that preferential segregation of calcium in the CaNi₅ alloy is mainly due to induced surface reaction with oxygen.     

Efficient algorithms for shortest distance queries on special classes of polygons

The problem of finding a rectilinear minimum bend path (RMBP) between two designated points inside a rectilinear polygon has applications in robotics and motion planning. In this paper, we present efficient algorithms to solve the query version of the RMBP problem for special classes of rectilinear polygons given their visibility graphs. Specifically, we show that given an unweighted graph G = (V, E), with ¦V¦ = N and ¦E¦ = M, algorithms to preprocess G in linear space and time such that the shortest distance queries — queries asking for the distance between any pair of nodes in the graph — can be answered in constant time and space are presented in this paper. For the case of a chordal graph G, our algorithms give a distance which is at most one away from the actual shortest distance. When G is a K-chordal graph, our algorithm produces an exact shortest distance in O(K) time. We also present a non-trivial parallel implementation of the sequential preprocessing algorithm for the CREW-PRAM model which runs in O(log² N) time using O(N + M) processors. After the preprocessing, we can answer the queries in constant time using a single processor.     

Some observations on the oxygen changes in a lake covered with Pistia stratiotes L.

A study has been made on the dissolved oxygen levels and pH changes in a polluted lake covered with Pistia stratiotes L. (water lettuce). The lake generally showed low levels of dissolved oxygen and low pH values. These could be attributed to the incoming organically rich water, coverage of the surface by Pistia plants and to the decomposition of these plants resulting in the formation of sludge at the bottom of the lake.     

A utility function model for optimal material choice for multifunctional performance

This paper presents a general solution technique for problems of multifactor optimization by a rationalised utility function model. Evaluation of the performance of materials and structures reflecting all the possible interplay of their components and attributes is rendered more realistic by this method as the individual utility for every function of the candidates is accurately computed from proper utility functions/curves which are constructed based on their respective functional behaviour. This is, perhaps, for the first time such rational utility curves are constructed and utilized. Evaluation by its very nature is subjective and this method is no exception but the decision is guided properly on rational lines reflecting the actual behaviour. The method is illustrated by an example problem on the choice of a particular material out of ten candidates for possible utilization as a compression panel of minimum weight, maximum stability, least cost and five other such desirable attributes. This model is the most appropriate for development of new materials (composites) and economic utilization of existing materials by effecting suitable trade offs, especially when mathematical programming methods are of no avail.     

Robustness of linear quadratic state feedback designs in the presence of system uncertainty

The well-known stabilizing property of linear quadratic state feedback (LQSF) design is used to obtain a quantitative measure of the robustness of LQSF designs in the presence of perturbations. Bounds are obtained for allowable nonlinear, time-varying perturbations such that the resulting closed-loop system remains stable. The special case of linear, time-invariant perturbations is also treated. The bounds are expressed in terms of the weighting matrices in a quadratic performance index and the corresponding positive definite solution of the algebraic matrix Riccati equation, and are easy to compute for any given LQSF design. A relationship is established between the perturbation bounds and the dominant eigenvalues of the closed-loop optimal system model. Some interesting asymptotic properties of the bounds are also discussed. An autopilot for the flare control of the Augmentor Wing Jet STOL Research Aircraft (AWJSRA) is designed, based on LQSF theory, and the results presented in this paper. The variation of the perturbation bounds to changes in the weighting matrices in the LQSF design is studied by computer simulations, and appropriate weighting matrices are chosen to obtain a reasonable bound for perturbations in the system matrix and at the same time meet the practical constraints for the flare maneuver of the AWJSRA. Results from the computer simulation of a satisfactory autopilot design for the flare control of the AWJSRA are presented.     

Analysis of thermal radiation,Joule heating,and viscous dissipation effects on blood-gold couple stress nanofluid flow driven by electroosmosis

Gold nanoparticles associated with DNA, RNA, proteins, oligonucleotides, and peptides are useful in therapies and drug delivery. The present article mainatins that gold nanoparticles play a tremendous role in remedying cancer and fatal diseases. A mathematical model is proposed for the two-dimensional motion of the couple stress nanofluid consisting of gold nanoparticles under the application of peristaltic propulsion and electroosmosis mechanisms in an asymmetric microchannel. The effects of radiation with slip boundary have been employed. The governing equations are simplified under the assumptions of low Reynolds number and long wavelength and the Poisson-Boltzmann equation is solved under Debye–Hückel linearization. Analytical solutions for the velocity of fluid motion, nanoparticle temperature, stream function, pressure gradient, are evaluated and analyzed graphically under the effects of various physical parameters. It is notable from the analysis that raising the Brinkman number boosts the nanoparticle temperature and heat transfer coefficient which validate the physical model and analysis. Moreover, it is noticed that sphere-shaped gold nanoparticles enhance the temperature as compared to other geometries of nanoparticles. The present study results may assist in developing the technology, smart micropumps, drugs, and device for hemodialysis and other health care applications.     

Programmable Self-Regulation with Wrinkled Hydrogels and Plasmonic Nanoparticle Lattices

This paper describes a self-regulating system that combines wrinkle-patterned hydrogels with plasmonic nanoparticle (NP) lattices. In the feedback loop, the wrinkle patterns flatten in response to moisture, which then allows light to reach the NP lattice on the bottom layer. Upon light absorption, the NP lattice produces a photothermal effect that dries the hydrogel, and the system then returns to the initial wrinkled configuration. The timescale of this regulatory cycle can be programmed by tuning the degree of photothermal heating by NP size and substrate material. Time-dependent finite element analysis reveals the thermal and mechanical mechanisms of wrinkle formation. This self-regulating system couples morphological, optical, and thermo-mechanical properties of different materials components and offers promising design principles for future smart systems.     

Security enhancement in video based on gatefold technique for copyright protection

Multimedia Tools and Applications - Watermarking of multimedia gives more attention to the research society. This paper presents the non-blind watermarking technique on video; initially, a...     

Bacterial infection and endotoxin in female reproductive tract in rats: correlation with the developmental status of preimplantation embryos

During mammalian preimplantation development, a substantial numbers of embryos are believed to be lost for reasons that are unclear. Using female rats, we investigated whether the developmental status of embryos is influenced by bacterial infection and endotoxin in the reproductive tract. From the vagina of cycling rats (n = 11), 21 bacterial isolates were identified; they were Streptococcus faecalis (S. faecalis; 38%), Escherichia coli (E. coli; 19%), Acinetobactor calcoaceticus (A. calcoaceticus; 14%), and coagulase negative staphylococcus (14%), Micrococcus sp. (5%), Bacillus subtilis (B. subtilis; 5%) and Proteus vulgaris (P. vulgaris; 5%). From the vagina of day 4 pregnant rats (n = 12), 26 isolates were identified; they were S. faecalis (23%), A. calcoaceticus (23%), E. coli (15%), Micrococcus sp. (15%), B. subtilis (8%), P. vulgaris (4%), Staphylococcus aureus (4%), beta-hemolytic streptococcus (4%) and Pseudomonas aeruginosa (4%). Gram negative bacteria found in the vagina of cycling and day 4 pregnant rats were 38% and 46%, respectively. In both, bacterial load was 10(3)-10(5) colony forming units and there was no association with the abnormality of the recovered embryos. However, in two day 4 pregnant animals, pathogenic bacteria (Staphylococcus aureus and beta-hemolytic streptococcus) were isolated and embryos recovered from them were degenerated and deformed. The vagina of day 9 pregnant animals (n = 7) were, however, sterile. Consistently, in all animals, the upper reproductive tract (uterus and oviduct) was devoid of any bacteria and no anaerobic bacteria were isolated from any part of the tract. The levels of endotoxin in the vagina of cycling and day 4 pregnant rats were 1.35 +/- 0.1 and 1.17 +/- 0.1 endotoxin units (EU), respectively. It was undetectable in the oviduct and uterus of all animals (n = 5) except one which showed high levels of endotoxin in uterus (4.5 EU) and oviduct (2.2 EU) and the animal also produced degenerated and deformed embryos. These results indicate that common bacterial flora of vagina may not affect embryo development and the presence of pathogenic bacteria in the vagina and/or endotoxin in reproductive tract could be detrimental to viability of gametes and preimplantation embryos in rats.