Optical properties of ultraphosphate glasses containing mixed divalent zinc and magnesium ions

Ternary zinc magnesium ultraphosphate glasses corresponding to (ZnO)x(MgO)30−x(P2O5)70 were prepared by melt quenching technique in the range of 5 ⩽ x ⩽ 20 mol%. The optical absorption spectra of the glasses were measured at room temperature in the wavelength range between 190 and 1100 nm, and the refractive indices of the glasses were measured at room temperature at a wavelength of 632.8 nm. The optical absorption spectra indicated that the electronic transition was indirect and associated with the phonon-assisted transition. From the absorption spectra, the optical energy band gap (Eopt) and Urbach energy (EU) values for all of the glass samples were calculated from their ultraviolet edges. The values of Eopt and EU were found to be in the range of 3.54–3.81 eV and 0.27–0.45 eV, respectively, both of which vary in a non-linear manner, with a turning point at 15 mol% of ZnO. The composition-dependence of these values has been suggested and analyzed in the light of switching role of Mg2+ based on its anomalous natural behavior from network builder to modifier depending upon its concentration. The values of refractive index ranged from 1.513 to 1.534. Variations in these optical parameters, as well as variations in density and molar volume are discussed and correlated with the structural changes within the glassy matrix

Dielectric spectroscopy on mixture of rice husk, rice husk ash and rice bran from 4 Hz to 1 MHz

In this study, mixtures of rice husk/rice husk ashes (RHA) with RB on different ratios were prepared. Dielectric permittivity (ε'), loss factor (ε") and AC conductivity (σ') were measured in the frequency range of 4 Hz to 1 MHz in ambient temperature. Results for mixture of RHA and RB indicate that a dipolar relaxation occurring between 103 - 105 Hz and the peak is depressed and shifted to lower frequency as the RB content increases in the mixture. Moreover, AC conductivity decreases as the RB content increase. This may attributed to production of natural oil content from RB. In contrast, a dielectric characteristic for RH is generally not affected by the RB contents. This study explore dielectric characteristic of mixture between RH/RHA and RB in low frequency range because lack of literature is reported on low frequency response. Additionally, the potential application of RH/RHA and RB could be explored in effort to diminish waste disposal and enhance environmental protection

Comparative study between measurement and predictions using geometrical optics and uniform theory of diffraction for case of non-line-of-sight (NLOS) in indoor environment

This paper describes the investigation and comparison of the accuracy of a deterministic model for a WLAN system in the indoor environment. The measurement system consisted of a spectrum analyzer and a log-periodic antenna. Non-line-of-sight (NLOS) propagation (in furnished rooms) was investigated. All the measurement sites mentioned in this paper are located in the Division of Information Technology at Universiti Putra Malaysia. The furnished rooms mentioned above were a teaching laboratory and a computer laboratory. The measured path losses were compared with the results obtained using deterministic models, namely the geometrical optics model and the uniform theory of diffraction model with the aid of image theory. The predicted results showed good agreement with the measured data for the NLOS environment, with an absolute mean error that ranged between 1.61 and 3.07 dB

Finite difference analysis of an open-ended, coaxial sensor made of semi- rigid coaxial cable for determination of moisture in Tenera oil palm fruit

In this paper, the use of the Finite Difference Method (FDM) is proposed to determine the reflection coefficient of an open-ended coaxial sensor for determining the moisture content of oil palm fruit. Semirigid open-ended coaxial sensor is used in conjunction with Vector Network Analyzer for reflection coefficient measurement of oil palm fruit. Moisture content in oil palm fruit determine optimum harvest time of oil palm fruit. Finite difference method is then used to simulate measured reflection coefficient due to different moisture contents in oil palm fruit at various stages of ripeness. The FDM results were found to be in good agreement with measured data when compared with the quasi-static and capacitance model. Overall, the mean errors in magnitude and phase for the FDM were 0.03 and 3.70°, respectively

A study assessing the association of glycated hemoglobin a1C (HbA1C) associated variants with HbA1C, chronic kidney disease and diabetic retinopathy in populations of asian ancestry

10.1371/journal.pone.0079767PLoS ONE811-POLN

Molecular fingerprinting of radiation resistant tumors: Can we apprehend and rehabilitate the suspects?

Radiation therapy continues to be one of the more popular treatment options for localized prostate cancer. One major obstacle to radiation therapy is that there is a limit to the amount of radiation that can be safely delivered to the target organ. Emerging evidence suggests that therapeutic agents targeting specific molecules might be combined with radiation therapy for more effective treatment of tumors. Recent studies suggest that modulation of these molecules by a variety of mechanisms (e.g., gene therapy, antisense oligonucleotides, small interfering RNA) may enhance the efficacy of radiation therapy by modifying the activity of key cell proliferation and survival pathways such as those controlled by Bcl-2, p53, Akt/PTEN and cyclooxygenase-2. In this article, we summarize the findings of recent investigations of radiosensitizing agents in the treatment of prostate cancer

The effect of physical changes in a furnished indoor environment on Wireless Local Area Network (WLAN) signals

This paper describes the investigation of the effect on the Wireless Local Area Network (WLAN) signals due to fixed and non-fixed variables in the indoor environment. The measurement system consisted of a spectrum analyzer and a log-periodic antenna. Line-of-sight (LOS) propagation and non-line-of-sight (NLOS) propagation (in furnished rooms) were discussed. All the measurement sites mentioned in this paper are located in the Division of Information Technology at Universiti Putra Malaysia. The furnished rooms included a teaching laboratory, a computer laboratory, and an operating office plus a server room. The effects of the various types of materials at the measurement sites also are described here

Dielectric and biodegradation properties of biodegradable nano-hydroxyapatite/starch bone scaffold

This study is aim to investigate the dielectric properties (dielectric constant, ε′ and loss factor, ε′′) and the biodegradation properties of the nano-hydroxyapatite/starch bone scaffold with various starch proportion in simulated body fluid. The nano-hydroxyapatite/starch bone scaffolds with starch proportions 30, 40, 50, 60, 70, 80, and 90 wt.% were fabricated. The ε′ and ε′′ of nano-hydroxyapatite/starch composite decrease when frequency increases. However, it increases when starch proportion and temperature increase. The biodegradation properties of the nano-hydroxyapatite/starch bone scaffold can be improved when the dielectric properties and porosity are enhanced. The enhancement of dielectric properties and porosity is due to the increment of starch proportion. The nano-hydroxyapatite/starch bone scaffold with the high starch proportion exhibits nano-hydroxyapatite/starch interfaces with strong intermolecular interactions that can stabilize biodegradation and biomineralization. The dielectric properties of the simulated body solutions are highly sensitive to the variation of the ion concentrations (calcium and phosphate). The nano-hydroxyapatite/starch bone scaffold with 80 wt.% starch proportion exhibits significant dielectric and biodegradation properties. It has potential to be a biodegradable inorganic/organic bone scaffold

Regression Analysis of the Dielectric and Morphological Properties for Porous Nanohydroxyapatite/Starch Composites: A Correlative Study

This paper aims to investigate the dielectric properties, i.e., dielectric constant (ε′), dielectric loss factor (ε″), dielectric tangent loss (tan δ), electrical conductivity (σ), and penetration depth (Dp), of the porous nanohydroxyapatite/starch composites in the function of starch proportion, pore size, and porosity over a broad band frequency range of 5 MHz–12 GHz. The porous nanohydroxyapatite/starch composites were fabricated using different starch proportions ranging from 30 to 90 wt%. The results reveal that the dielectric properties and the microstructural features of the porous nanohydroxyapatite/starch composites can be enhanced by the increment in the starch proportion. Nevertheless, the composite with 80 wt% of starch proportion exhibit low dielectric properties (ε′, ε″, tan δ, and σ) and a high penetration depth because of its highly interconnected porous microstructures. The dielectric properties of the porous nanohydroxyapatite/starch composites are highly dependent on starch proportion, average pore size, and porosity. The regression models are developed to express the dielectric properties of the porous nanohydroxyapatite/starch composites (R2 > 0.96) in the function of starch proportion, pore size, and porosity from 1 to 11 GHz. This dielectric study can facilitate the assessment of bone scaffold design in bone tissue engineering applications