Segmented phase of ultraviolet (UV) curable thermoset polyurethanes-graphite (TPU-G) composites

Segmented thermoset polymeric materials properties mainly classified through its carbonyl hydrogen bonding. The addition of graphite particle loading in polymeric materials tailored the functional characteristic of the composites. Therefore, the carbonyl hydrogen bonding in the hard segments of the synthesized segmented ultraviolet (UV) curable thermoset polyurethanes-graphite (TPU-G) composites was identified. This composites based green polymer incorporated with varying graphite particles loading were prepared through slip casting method which cure upon UV light. These result in an enhancement of the carbonyl hydrogen bonding which tribute to degree of phase separation (DPS %) in the TPU-G composites ranged from 10-20%, as compared to that in the pure TPU. In addition, the spectroscopy detects the formation of carbonyl hydrogen groups within the TPU-G composites although they are prone to chain scission and undergo photo oxidation subjected to ultraviolet (UV) curing. Upon UV curing, higher graphite weight loading (TPU-G20, TPU-G25 and TPU-G30 composites), shows higher and stable DPS% value, attribute to soft segment- soft segment and hard segment- hard segment establishment. Therefore, the graphite particles dominantly absorb the incident radiation instead of thermoset polyurethane without changing its based

Availability analysis of terrestrial free space optical (FSO) link using visibility data measured in tropical region

Haze and rain are the most impairments factors to free space optical (FSO) links. These weather conditions limit the visibility, and thereby causes high attenuation of the optical signal. This high attenuation reduces the availability performance of the FSO link. This study evaluates the performance of a terrestrial FSO link under tropical climate conditions. The performance analysis is evaluate over 5 km link distance. The cumulative distribution function (CDF) of the received signal to noise ratio (SNR) is used to study the outage performance of the FSO link under haze conditions. The performance analysis is based on three years measured visibility data in Malaysia. Based on the statistical analysis, link availability of 99.99% can be achieved for 37.44 dB SNR over 1 km link distance. Carrier class availability “five nine” can be achieved for 20 dBm transmission power using 1550 nm wavelength

Green tea polyphenol-reduced graphene oxide: derivatisation, reduction efficiency, reduction mechanism and cytotoxicity

This paper reports on the derivatisation, reduction efficiency, reduction mechanism and cytotoxicity of green tea polyphenol-reduced graphene oxide (GTP-RGO). The reduction of graphene oxide (GO) at 90°C using a weight ratio (WR) of GTP/GO=1 resulted in the production of a stable GTP-RGO dispersion in aqueous media, as indicated by the results of ultravioletvisible (UV-Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and the measurement of zeta potential and electrophoretic mobility. In addition, the results from UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis indicated the comparable reduction ability of GTP relative to the standard reducing agent, hydrazine (N2H4). The removal mechanism of epoxy group from GO via reduction reaction with GTP was investigated by implementing hybrid functional method of Becke-3-parameters-Lee-Yang-Parr (B3LYP)using Gaussian 09 software. The energy and frequency calculations showed that the GO reduction using GTP was more spontaneous and relatively took place faster than the reduction using N2H4, as evidenced by higher entropy change (ΔS) (0.039 kcal/mol·K) and lower Gibbs free energy (ΔG) barrier (58.880 kcal/mol).The cytotoxicities of GO and GTP-RGO samples were evaluated against human colonic fibroblasts cells (CCD-18Co). The GO sample was determined to be toxic even at low concentration (6.25 μg/mL), while the GTP-RGO sample possesses notably low toxicity at the same concentration. The cell culture experiments revealed that the incorporation of GTP led to a decrease in the toxicity of GTP-RGO samples

Quantum transport across van der Waals domain walls in bilayer graphene

Bilayer graphene can exhibit deformations such that the two graphene sheets are locally detached from each other resulting in a structure consisting of domains with different inter-layer coupling. Here we investigate how the presence of these domains affect the transport properties of bilayer graphene. We derive analytical expressions for the transmission probability, and the corresponding conductance, across walls separating different inter-layer coupling domain. We find that the transmission can exhibit a valley-dependent layer asymmetry and that the domain walls have a considerable effect on the chiral tunnelling properties of the charge carriers. We show that transport measurements allow one to obtain the strength with which the two layers are coupled. We performed numerical calculations for systems with two domain walls and find that the availability of multiple transport channels in bilayer graphene modifies significantly the conductance dependence on inter-layer potential asymmetry.Comment: 20 pages, 24 Figure

Pendugaan Jenis Batuan Bawah Permukaan Daerah Bendungan Karangkates Menggunakan Metode Geomagnetik

Telah dilakukan studi geofisika dengan metode geomagnetik di daerah bendungan Karangkates (Lahor-Sutami). Pengukuran dilakukan menggunakan Proton Procession Magnetometer (PPM) dimana spasi antar titik pengukuran 500 meter dan didapatkan sebanyak 88 titik ukur. Pengolahan data menggunakan software Surfer versi 10 dan Mag2DC untuk mendapatkan penampang model anomali magnetik. Diperoleh nilai anomali magnetik total berkisar antara -600 nT sampai dengan 1600 nT. Dari pemodelan yang telah dilakukan didapatkan beberapa jenis batuan yaitu berupa tuf pasiran, batu apung dan lava

Preliminary study of heavy metals pollution in freshwater fishes of Sungai Simpang Empat, Penang. / F. Widad and M. Abdullah

A study was conducted to determine heavy metals content in different body parts of fish collected from five sampling stations in Sungai Simpang Empat, Penang from July to December, 2005. The liver, head, gills, muscles and bones of dried fish samples were extracted by the AOAC acid digestion method whilst iron (Fe), zinc (Zn), manganese (Mn), lead (Pb), chromium (Cr), copper (Cu), nickel (Ni) and cadmium (Cd) were analyzed by atomic absorption spectrophotometry. Based on Interim National Water Quality Standard for Malaysia (INWQS), dissolved oxygen, pH, conductivity, ammonia, sulphate, nitrate and phosphate were within the recommended levels suggested for fish to survive except for turbidity levels in some stations, exceeding the recommended of 50 mg/L limit. Fe was accumulated at the highest levels while Cd was the lowest. Only Fe and Mn levels have exceeded the permissible limit of the Malaysian Food Act (1983) and Food Regulations (1985). In most of the fish, liver accumulated the highest concentration of all heavy metals compared to head, gills, muscles and bones. Snakeskin gouramy or Sepat Siam (Trichogaster pectoralis) and black tilapia (Oreochromis mossambicus) are good candidates for potential bioindicator for metals pollution in this study

A novel Multi-permittivity Cylindrical Dielectric Resonator Antenna for Wideband Applications

In this paper, a novel multi-permittivity cylindrical dielectric resonator antenna for wideband application is presented. The multi-permittivity cylinder is formed by combining two different permittivity material sectors in such a way that each sector (with constant permittivity) is 90 degree apart. A direct microstrip line coupling terminated with T-stub at the open end is used to excite the multi-permittivity cylindrical dielectric resonator. The angular position of the multi sector dielectric resonator with respect to the longitudinal axis of the microstrip line and length of the additional strip at the open end of the feeding circuit is key parameters for wideband operation of the antenna. By optimizing all parameters of the proposed antenna, wideband impedance bandwidth of 56% (12.1 GHz - 21.65 GHz) is achieved. The average gain of the antenna throughout the bandwidth is 5.9 dB with good radiation properties in both E-plane and H-plane. A well matched simulation and experimental results show that the antenna is suitable for wideband applications

Comparison of Constraints Handling Methods for Economic Load Dispatch Problem using Particle Swarm Optimization Algorithm

The main goal of economic load dispatch (ELD) problem is to find an optimal operating condition for the committed generating units in order to minimize total operational cost while satisfying the constraints. The ELD problem becomes more complicated and non-convex when valve point effects of the generator are considered. The penalty function approach (PFA) is widely used to handle the constraints in ELD problem due to simple implementation. However, it requires a proper penalty factor tuning and provides inconsistent result. This paper investigates the performances of modification of infeasible particle (MIP) method based on particle swarm optimization (PSO) for solving ELD problem. The performances of MIP and PFA methods have been compared in terms of optimal result, convergence characteristic and robustness. The proposed MIP and PFA have been tested on three standard test systems (consists of 3, 6 and 40 generating units) to validate their effectiveness. The simulation result confirmed that MIP has better convergence characteristic and more robust compared to PFA. Therefore, the MIP approach can be applied in any optimization algorithm for solving constraint ELD problem effectively

Pengaruh Faktor Keperilakuan Organisasi terhadap Implementasi Sistem Akuntansi Keuangan Daerah pada Satuan Kerja Perangkat Daerah Kabupaten Bengkalis

This study aims to determine how much influence superiors support, clarity of purpose and training on the implementation of regional financial accounting systems in the work unit of Bengkalis regency. The type of data from this study is quantitative descriptive using primary and secondary data. The data analysis technique used is multiple linear regression. The results of this study are the influence of organizational behavioral factors with a percentage value of 0.677 or 67.7% and the remaining 32.3% is influenced by other variables, namely the Regional Supervision Agency, internal control system, and organizational culture. This research is the latest research in Bengkalis Regency and can be a reference for further research