Effect of titania particles preparation on the properties of Ni–TiO2 electrodeposited composite coatings

In this paper, the effect of titania particles preparation on the properties of Ni–TiO₂ electrocomposite coatings has been addressed. Titania particles were prepared by precipitation method using titanium tetrachloride as the precursor. The titanyl hydroxide precipitate was subjected to two different calcinations temperatures (400 and 900 °C) to obtain anatase and rutile titania particles. These particles along with commercial anatase titania particles were separately dispersed in nickel sulfamate bath and electrodeposited under identical electroplating conditions to obtain composite coatings. The electrodeposited coatings were evaluated for their microhardness, wettability, corrosion resistance, and tribological behavior. The variation of microhardness with current density exhibited a similar trend for all the three composite coatings. The composite coating containing anatase titania particles exhibited higher microhardness and improved wear resistance. However, the corrosion resistance of the composite coating containing commercial titania powder was superior to that of plain nickel, Ni–TiO₂ composite coatings containing anatase and rutile titania particles. The poor corrosion resistance of these composite coatings was attributed to the higher surface roughness of the coatings. This problem was alleviated by incorporating ball-milled titania powders. The composite coatings with higher surface roughness were modified with a low surface energy material like fluoroalkyl silane to impart hydrophobic and superhydrophobic properties to the coatings. Among these coatings, Ni–TiO₂–9C coating exhibited the highest water contact angle of 157°.     

Quasi‐Continuous Wave Near‐Infrared Excitation of Upconversion Nanoparticles for Optogenetic Manipulation of C. elegans

Optogenetics is an emerging powerful tool to investigate workings of the nervous system. However, the use of low tissue penetrating visible light limits its therapeutic potential. Employing deep penetrating near‐infrared (NIR) light for optogenetics would be beneficial but it cannot be used directly. This issue can be tackled with upconversion nanoparticles (UCNs) acting as nanotransducers emitting at shorter wavelengths extending to the UV range upon NIR light excitation. Although attractive, implementation of such NIR‐optogenetics is hindered by the low UCN emission intensity that necessitates high NIR excitation intensities, resulting in overheating issues. A novel quasi‐continuous wave (quasi‐CW) excitation approach is developed that significantly enhances multiphoton emissions from UCNs, and for the first time NIR light‐triggered optogenetic manipulations are implemented in vitro and in C. elegans. The approach developed here enables the activation of channelrhodopsin‐2 with a significantly lower excitation power and UCN concentration along with negligible phototoxicity as seen with CW excitation, paving the way for therapeutic optogenetics.     

Growth of ZnO nanostructures: Cones,rods and hallow-rods,by microwave assisted wet chemical growth and their characterization

ZnO nanostructures were grown by microwave assisted wet-chemical growth, at different microwave powers and for different growth durations. The grown nanostructures were analysed for their morphological, structural, compositional and optical characteristics. The total microwave power per growth run (product of microwave power and growth duration, with units in watt-min), has a linear relationship with most of the characteristics of the grown ZnO nanostructures. It is shown that by altering the microwave power per growth run, the morphology of the individual ZnO nanostructure can be changed from cones with hexagonal cross section, to faceted hexagonal nanorods, to hollow hexagonal nanorods. It is observed that, while the fast growth rate along the high energy polar faces (0001) and (000ī) of ZnO is the reason behind the formation of one dimensional ZnO structures (cones and rods), the process of formation of hallow ZnO rods is due to further etching/material-removal from the tip of the rods, at high microwave power conditions at long growth durations.     

Hydroquinone increases the frequency of micronuclei in a dose-dependent manner in mouse bone marrow

The frequency of micronuclei (micronucleated polychromatic erythrocytes, MPCE and micronucleated normochromatic erythrocytes, MNCE) was studied at 12, 24 and 36 h post-treatment in the bone marrow of mice treated with 0, 0.78, 1.56, 3.125, 6.25, 12.5, 25, 50, 75 and 100 mg/kg body wt of hydroquinone (HQ). Treatment of mice with various doses of HQ resulted in a dose dependent increase in the frequency of both MPCE and MNCE at all the post-treatment time periods. The frequency of MPCE was significantly higher after administration of 3.125 mg/kg HQ at 24 h post-treatment, except 12 and 36 h, where a significant increase in the frequency of MPCE was observed only after administration of 6.25 mg/kg drug dose. Similarly, a significant increase in the frequency of MNCE was observed after 12.5 mg/kg HQ treatment at all the post-treatment time periods. The dose effect relationship between various HQ doses and MPCE and MNCE induction was linear and linear quadratic, respectively at all the post-treatment time periods. The PCE/NCE ratio declined in a dose dependent manner at all the post-treatment time periods and this decline was significant when compared to non-drug treated controls. The dose effect relationship was linear quadratic at all the post-treatment time periods studied.     

Dependence of computed trajectory on step-size in a nonlinear dynamic system: an investigation into cutting tool dynamics

The nonlinear model of an orthogonal cutting process devised by Grabec is studied to demonstrate the importance of choosing an appropriate step-size and evolutionary algorithm for numerically integrating a system of nonlinear differential equations. Two different algorithms are used for computing the system trajectory, and the dependence of the phase portrait on the step-size is shown. A qualitative understanding to connect the proper step-size and the system nonlinearity is established.     

Turn-taking as a design principle for barge-in in Spoken Language Systems

It is widely acknowledged that users of Spoken Language Systems (SLS) want the ability to truncate system prompts by using a barge-in capability (e.g., Basson et al., 1995; Yankelovich et al., 1995). However, little has been published on how barge-in is used or if it adversely affects Automatic Speech Recognition (ASR) and the interface usability. Typically, user requests for barge-in are assumed to be based on the desire to make system interactions faster and therefore more similar to interactions with touch-tone systems. We believe that requests for a barge-in capability are rooted in the notion of discourse as a turn-taking event. Viewed in this way, we believe SLS can be enhanced to develop speech interfaces that are deemed more natural by users, as well as to increase system performance. This study addressed several issues. We found that users new to the system did not need to be informed about the barge-in capability before they attempted barge-in, that they used barge-in during almost half of their interactions with the system, and that they had identifiable patterns of barge-in use consistent with the turn-taking model. Results are presented and consequences for speech interface design as well as algorithm enhancement are discussed.     

Rapid Method for the Preparation of 123 Superconductor Using Microwaves

A novel and rapid method to prepare 123 superconductor powder based on microwave processing is reported. A mixture of the nitrates of Y, Ba, and Cu in 123 stoichiometry when subjected to microwaves of frequency 2.45 GHz for 240 s resulted in an appreciable quantity of tetragonal 123 phase. Annealing for a period of 4 h at 940°C in flowing oxygen formed a superconductor having a T _c of 91 K. Sintered pellets of the powder formed by microwave processing have shown transport J _c of 105 A/cm².     

Function-to-structure transformation in conceptual design: An associative memory-based paradigm

The three most important phases of design are (1) conceptual phase; (2) configuration phase; and (3) parameterization phase. The second and the third phases are well researched. However, little work has been done in the conceptual design phase. In this paper the author deals with a different way of modeling the conceptual design phase. In this research the paradigm of function-to-structure transformation is used. One of the most difficult ideas of design is that of modeling the function-to-structure transformation process. The current research shows that the function-to-structure transformation is accomplished through a process of association. Whenever a designer is faced with finding a solution to a new functional requirement, the designer tries to associate this new function with known functions from his/her memory through a process of association. After having identified the closest function, an associated structure can be retrieved and mutated to form the design solution for the new problem. In essence, the designer associates the new functions with known functions and will try to retrieve the closest and most general design solution from his/her memory through a process of association. The author models the human associative memory through artificial neural networks (ANN) with back-propagation. A simple yet illustrative example of cups and containers is selected to model the function-to-structure transformation process at the conceptual design phase. In this paper the implementation aspects of the ANN are clearly explained. The robustness of the ANN through different schemes is also explored. A performance analysisvia simulation by varying the nodes of the hidden layer is also carried out.