Influence of absorbed water on the dielectric properties and glass-transition temperature of silica-filled epoxy nanocomposites

Work on dielectric spectroscopy of epoxy resin filled with nano-SiO2 at different relative humidities and temperatures is reported. Above the glass-transition temperature (Tg), dc-like imperfect charge transport (QDC or LFD) dominates the low frequency dielectric spectrum. Another mid-frequency relaxation process was found in the non-dried composites. Water also induces glass-transition temperature decreases, which can be measured both by dielectric spectroscopy and DSC. Both theory and experiment demonstrated that a higher water content could exist in nanocomposites than unfilled epoxy suggesting a bigger free volume when nanostructured. In our system, the hydrophilic surface of silica is likely to cause water to surround and lead to delamination of the epoxy from SiO2. This is a potential mechanical and dielectric weakness in the nanocomposites, which may lead to an ageing phenomenon. Hydrophobic surface group may reduce the water adsorption in nanocomposites

WSN based intelligent cold chain management

This paper presents a cold chain monitoring system which is implemented by using ubiquitous computing technologies, Radio Frequency Identification (RFID) & Wireless Sensor Network (WSN). In this paper, we discuss how cold supply chain works and how we can monitor and control cold supply chain by using wireless tracking and sensing technologies. We propose a prototype design which will provide a well controlled and transparent cold chain system, which could help the users to manage their products’ environmental data in real time during the life cycle. Moreover, we highlight how the availability of product trace data in combination with historical condition-monitoring data can facilitate decision-making processes enhancing supply chain’s performance. Finally we discuss the integration works of these two technologies together in the cold supply chain management system. Hardware and software platform of WSN used in this system are also described in this paper

High-frequency shoot regeneration of nodal explants from Tetrastigma hemsleyanum Diels et Gilg: A valuable medicinal plant

This paper describes the shoot regeneration of nodal segments from a medicinal plant, Tetrastigma hemsleyanum Diels et Gilg (Vitaceae). The highest number of shoots (7.27 shoots per explant) was observed in MS medium supplemented with 4 mg/l BA after six weeks of inoculation. 2 mg/l BA in combination with 0.1 mg/l NAA not only induced shoot proliferation but also increased shoot length. Well-developed shoots were rooted on half strength MS medium supplemented with 2 mg/l IBA with 100% rooting and 85% of the regenerated plantlets survived before been transferred to field conditions.Key words: Medicinal plant, nodal explants, shoot regeneration, Tetrastigma hemsleyanum

Search for Spin-Dependent Short-Range Force Using Optically Polarized 3^3He Gas

We propose a new method to detect short-range \textit{P-} and \textit{T-} violating interactions between nucleons, based on measuring the precession frequency shift of polarized $^3$He nuclei in the presence of an unpolarized mass. To maximize the sensitivity, a high-pressure $^3$He cell with thin glass windows (250 $\rm\mu m$) is used to minimize the distance between the mass and $^3$He. The magnetic field fluctuation is suppressed by using the $^3$He gas in a different region of the cell as a magnetometer. Systematic uncertainties from the magnetic properties of the mass are suppressed by flipping both the magnetic field and spin directions. Without any magnetic shielding, our result has already reached the sensitivity of the current best limit. With improvement in uniformity and stability of the field, we can further improve the sensitivity by two orders of magnitude over the force range from $10^{-4}-10^{-2}$ m

Particle-Hole Asymmetry in Doped Mott Insulators: Implications for Tunneling and Photoemission Spectroscopies

In a system with strong local repulsive interactions it should be more difficult to add an electron than to extract one. We make this idea precise by deriving various exact sum rules for the one-particle spectral function independent of the details of the Hamiltonian describing the system and of the nature of the ground state. We extend these results using a variational ansatz for the superconducting ground state and low lying excitations. Our results shed light on the striking asymmetry in the tunneling spectra of high Tc superconductors and should also be useful in estimating the local doping variations in inhomogeneous materials.Comment: 4 pages, no figure

Fundamentals of microcrack nucleation mechanics

A foundation for ultrasonic evaluation of microcrack nucleation mechanics is identified in order to establish a basis for correlations between plane strain fracture toughness and ultrasonic factors through the interaction of elastic waves with material microstructures. Since microcracking is the origin of (brittle) fracture, it is appropriate to consider the role of stress waves in the dynamics of microcracking. Therefore, the following topics are discussed: (1) microstress distributions with typical microstructural defects located in the stress field; (2) elastic wave scattering from various idealized defects; and (3) dynamic effective-properties of media with randomly distributed inhomogeneities

General covariant Horava-Lifshitz gravity without projectability condition and its applications to cosmology

We consider an extended theory of Horava-Lifshitz gravity with the detailed balance condition softly breaking, but without the projectability condition. With the former, the number of independent coupling constants is significantly reduced. With the latter and by extending the original foliation-preserving diffeomorphism symmetry ${{Diff}}(M, {\cal{F}})$ to include a local U(1) symmetry, the spin-0 gravitons are eliminated. Thus, all the problems related to them disappear, including the instability, strong coupling, and different speeds in the gravitational sector. When the theory couples to a scalar field, we find that the scalar field is not only stable in both the ultraviolet (UV) and infrared (IR), but also free of the strong coupling problem, because of the presence of high-order spatial derivative terms of the scalar field. Furthermore, applying the theory to cosmology, we find that due to the additional U(1) symmetry, the Friedmann-Robertson-Walker (FRW) universe is necessarily flat. We also investigate the scalar, vector, and tensor perturbations of the flat FRW universe, and derive the general linearized field equations for each kind of the perturbations.Comment: 19 pages, comments are welcome!!