Gold nanoparticle-coated biomaterial as SERS micro-probes

We report for the first time, on the utility of plant-based biomaterial as enhanced-Raman scattering probes. The bio-substrate used in this study are commonly found in plant extracts, and are cost-effective, mechanically robust, flexible and easily transportable. The probe was fabricated by coating the plant extract with gold nanoparticles and characterized. By employing a ‘single-touch contact’ method, we reveal the ability of these probes to detect routinely used Raman markers such as 2-napthalenethiol and rhodamine B, at nano-molar concentrations, in dry and liquid forms, respectively. Reproducibility of the signals with variation <5%, and the ability to detect biomolecules are demonstrated herein. We envision these bio-probes as potential candidates for enhanced Raman sensing in chemical, environmental, and archaeological applications. By further engineering the shape, morphology, and surface chemistry of these micro-probes, we foresee their utility as miniaturized, natural SERS substrates.     

Structural characteristics of titanium coating on copper substrates

The growth characteristics of titanium films deposited on glass, silicon (100) and oxygen free high purity copper substrate using magnetron sputtering have been investigated using X-ray diffraction, electron microscopy and scratch indentation techniques. The study of interface between the titanium film and the substrate was carried out to determine coating thickness, as well as intermixing of the elements at the interface. Studies revealed that the interface is free from voids and intermixing of the film and the substrate. Microstructural and diffraction analysis showed that the Ti coating was polycrystalline and exhibited columnar growth. The Ti crystallite size varied between 24 and 58 nm depending on the substrate. The thickness of the films were typically about 4 μm. Scratch test indicated that the films are adherent and the first critical load to failure was observed to be 4·5 N ± 2 N.     

Balanced gait generations of a two-legged robot on sloping surface

In this paper, dynamically balanced gait generation problem of a 7-DOF two-legged robot moving up and down through the sloping surface is presented. The gait of the lower links during locomotion is obtained after assuming suitable trajectories for the swing leg and hip joint. The trunk motion is initially generated based on the concept of static balance, which is different from the well-known semi-inverse method and then checked for its dynamic balance calculated using the concept of Zero-Moment Point (ZMP). Lagrange–Euler formulation is attempted for the determination of joint torques. Average power consumption at each joint is then determined based on the computed torques. Moreover, the variations of dynamic balance margin and average power consumption are studied for both ascending and descending through the sloping surface. Both of them are found to be more for the ascending gait generation compared to those for the descending case. The effects of variations of the slope have also been studied on the average dynamic balance margin and power consumption for both the cases.     

Switched-capacitor filters using unity-gain amplifiers

Switched-capacitor networks realizing second-order filter characteristics are presented. Realization is achieved with unity-gain amplifiers as buffers. The circuits have small sensitivities, good dynamic range and a reasonable spread of capacitor values. The filters can be used for high-Q realization and a relatively high frequency range.     

Extending the bandwidth of an instrumentation amplifier

A new configuration for operational amplifier based instrumentation amplifier is presented. The analytical expressions are obtained and the performance of the proposed circuit is examined in relation to the conventional circuit. Simulation and experimental results are presented which establish the superiority of the proposed instrumentation amplifier topology over the conventional circuit. The effect of second pole of op amps on the circuit stability has also been investigated. Numerical results are given in support of theoretical conclusions.     

Inclusion of minority charge carriers in the solution of Poisson's equation for a metal semiconductor contact in thermal equilibrium†

A theory of the space-charge capacitance of a metal-semiconductor contact has been developed by solving the Poisson equation for the space-charge region under zero current condition. The space charge is assumed to consist not only of ionized donors and acceptors but also of electrons and holes. An explicit expression for the space-charge capacitance under those general conditions is given. In an appendix a procedure is outlined whereby the theory could be developed for the case of Fermi statistics with partially ionized donors.     

Green biomass active electronic diode

For the first time, a biomass electronic junction functioning as a conventional electronic diode inside green leaves of Vinka-rosa and Plumeria rubra mass structure has been experimentally predicted and studied. The experimental diode demonstrated appropriate conventional electronic diode characteristics. The predicted diode junctions were operated for forward and reverse dc voltage biases in the range of ±1 to 10 and 1 to 30?V respectively. The studies revealed a strong functional dependence on the water content of the green leaf. These studies are sequential to the very recently reported research work of Kosta et al. on bioelectronics and soilelectronics. The study speculatively forecasts the beginning of a new revolutionary era of green biomass electronic circuitry.     

The textural properties of soy paneer

Toned dairy milk and soy milk were mixed in different proportions and coagulated at various temperatures to produce paneer blends, and their textural properties were evaluated. As the soy milk proportion in the blend increased from 0% to 50%, hardness, cohesiveness and chewiness of the samples decreased initially, but further increase in the blend from 50% to 100% cause these values to increase slightly. The proportion of soymilk in the prepared paneer had a significant effect on hardness, cohesiveness, adhesiveness, chewiness and yield, whereas the coagulation temperature affected cohesiveness and yield. The process parameters did not show any effect on the springiness.     

EFFECT OF CHILLING AND FREEZING ON SURVIVAL OF VIBRIO PARAHAEMOLYTICUS ON FISH FILLETS1

Vibrio parahaemolyticus is a foodborne pathogen isolated from coastal waters of the United States, and from seafoods including fish. No information is available on the viability of V. parahaemolyticus on raw, chilled and frozen fish. A three‐strain mixture of V. parahaemolyticus was inoculated on fish fillets (pH 6.4) to obtain a bacterial load of 10⁴ (high) or 10³ (low) CFU/fillet, and stored at 4C or 8C for 9 days or at – 18C for seven weeks. At 4C and 8C, and at both levels of inoculation, V. parahaemolyticus survived on the fillets for the entire duration of the study. However, there was a significant reduction (P < 0.01) in V. parahaemolyticus population on the fillets by 9 days of storage. In the frozen fillets, there was a sharp decline (P < 0.01) in the population of V. parahaemolyticus by day 5 of storage. Although chilling and freezing significantly (P < 0.01) inactivated high numbers of V. parahaemolyticus on fish, they cannot be relied upon as a method to reduce V. parahaemolyticus on fish, since the time and magnitude of reduction depends on the initial load of the pathogen and the storage temperature.     

EFFECT OF COMBINATION DRYING ON THE PHYSICO-CHEMICAL CHARACTERISTICS OF CARROT AND PUMPKIN

The quality of dehydrated carrot and pumpkin pieces produced by combination drying employing partial freeze-drying and hot air-drying were investigated. The drying rate, the total energy requirement and the physico-chemical properties of the combination dried (CD) products were compared with those of hot air-dried (HAD) and freeze-dried (FD) products. The total carotenoid content of the two vegetables (1050 ppm and 160 ppm) was significantly affected by drying processes. Destruction of carotenoids during storage at different temperatures was less in the CD samples. The HAD vegetables exhibited shrinkage, case hardening and poor rehydration (25 and 28 min in cold water, rehydration ratio 1:2.6 and 1:2.9, respectively). The FD vegetables appeared wholesome, porous, well formed with excellent rehydration features at room temperature (rehydration time 2 and 3 min in cold water, rehydration ratio 1:7 and 1:6.9, respectively). The CD vegetables were comparatively superior to HAD products and were nearer in quality to FD products with respect to appearance, rehydration (9 and 10 min in cold water, rehydration ratio 1:5 and 1:4, respectively). The drying time and total energy for CD processing was 50% less than for FD but similar to HAD. The combination dehydration process is effective in obtaining high quality dehydrated vegetables.