Search results for: plasma layer thickness

Authors: Ishak Suleiman, Ahmad Kamsani Samingan, Yeoh Chun Yeow, Abdul Aziz Bin Abdul Rahman

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In this paper, we evaluate the benefits of distributed 4x4 MIMO LTE downlink systems compared to that of the co-located 4x4 MIMO LTE downlink system. The performance evaluation was carried out experimentally by using Wireless Open-Access Research Platform (WARP), where the comparison between the 4x4 MIMO LTE transmission downlink system in distributed and co-located techniques was examined. The measured Error Vector Magnitude (EVM) results showed that the distributed technique achieved better system performance compared to the co-located arrangement.

Keywords: multiple-input-multiple-output (MIMO), distributed MIMO, co-located MIMO, LTE

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Authors: Jigar N. Shah, Hiral J. Shah, Praful D. Bharadia

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The major challenge faced by formulation scientists in transdermal drug delivery system is to overcome the inherent barriers related to skin permeation. The stratum corneum layer of the skin is working as the rate limiting step in transdermal transport and reduce drug permeation through skin. Many approaches have been used to enhance the penetration of drugs through this layer of the skin. The purpose of this study is to investigate the development and evaluation of a combined approach of drug carriers and iontophoresis as a vehicle to improve skin permeation of an analgesic drug. Iontophoresis is a non-invasive technique for transporting charged molecules into and through tissues by a mild electric field. It has been shown to effectively deliver a variety of drugs across the skin to the underlying tissue. In addition to the enhanced continuous transport, iontophoresis allows dose titration by adjusting the electric field, which makes personalized dosing feasible. Drug carrier could modify the physicochemical properties of the encapsulated molecule and offer a means to facilitate the percutaneous delivery of difficult-to-uptake substances. Recently, there are some reports about using liposomes, microemulsions and polymeric nanoparticles as vehicles for iontophoretic drug delivery. Niosomes, the nonionic surfactant-based vesicles that are essentially similar in properties to liposomes have been proposed as an alternative to liposomes. Niosomes are more stable and free from other shortcoming of liposomes. Recently, the transdermal delivery of certain drugs using niosomes has been envisaged and niosomes have proved to be superior transdermal nanocarriers. Proniosomes overcome some of the physical stability related problems of niosomes. The proniosomal structure was liquid crystalline-compact niosomes hybrid which could be converted into niosomes upon hydration. The combined use of drug carriers and iontophoresis could offer many additional benefits. The system was evaluated for Encapsulation Efficiency, vesicle size, zeta potential, Transmission Electron Microscopy (TEM), DSC, in-vitro release, ex-vivo permeation across skin and rate of hydration. The use of proniosomal gel as a vehicle for the transdermal iontophoretic delivery was evaluated in-vitro. The characteristics of the applied electric current, such as density, type, frequency, and on/off interval ratio were observed. The study confirms the synergistic effect of proniosomes and iontophoresis in improving the transdermal permeation profile of selected analgesic drug. It is concluded that proniosomal gel can be used as a vehicle for transdermal iontophoretic drug delivery under suitable electric conditions.

Keywords: iontophoresis, niosomes, permeation enhancement, transdermal delivery

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Authors: Thomas Merciris, Mathieu Masquere, Yann Cressault, Pascale Petit

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The goal of an alternative current (AC) switching device is to allow the arc (created during the opening phase of the contacts) to extinguish at the current zero. The plasma temperature rate of cooling down, the electrical characteristic of the arc (current-voltage), and the rise rate of the transient recovery voltage (TRV) are critical parameters which influence the performance of a switching device. To simulate the thermal extinction of the arc and to obtain qualitative data on the processes responsible for this phenomenon, a 1D MHD fluid model in the air was developed and coupled to an external electric circuit. After thermal extinction, the dielectric strength of the hot air (< 4kK) was then estimated by the Bolsig+ software and the critical electric fields method with the temperature obtained by the MHD simulation. The influence of copper Cu and silver Ag vapors was investigated on the thermal and dielectric part of the simulation with various current forms (100A to 1kA). Finally, those values of dielectric strength have been compared to the experimental values obtained in the case of two separating silver contacts. The preliminary results seem to indicate the dielectric strength after multiples hundreds of microseconds is the same order of magnitude as experimentally found.

Keywords: MHD simulation, dielectric recovery, Bolsig+, silver vapors, copper vapors, breakers, electric arc

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Authors: Punnoose A. K.

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This paper presents an approach for identifying noisy speech recording using a multi-layer perception (MLP) trained to predict phonemes from acoustic features. Characteristics of the MLP posteriors are explored for clean speech and noisy speech at the frame level. Appropriate density functions are used to fit the softmax probability of the clean and noisy speech. A function that takes into account the ratio of the softmax probability density of noisy speech to clean speech is formulated. These phoneme independent scoring is weighted using a phoneme-specific weightage to make the scoring more robust. Simple thresholding is used to identify the noisy speech recording from the clean speech recordings. The approach is benchmarked on standard databases, with a focus on precision.

Keywords: noisy speech identification, speech pre-processing, noise robustness, feature engineering

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Authors: Khushalini N. Ulman, Samane Maroufi, Veena H. Sahajwalla

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Globally, electronic waste (e-waste) continues to grow at an alarming rate. Several technologies have been developed to recover valuable materials from e-waste, however, their efficiency can be increased with a better knowledge of the e-waste components. Random access memory cards (RAMs) are considered as high value scrap for the e-waste recyclers. Despite their high precious metal content, RAMs are still recycled in a conventional manner resulting in huge loss of resources. Our research work highlights the precious metal rich components of a RAM. Inductively coupled plasma (ICP) analysis of RAMs of six different generations have been carried out and the trends in their metal content have been investigated. Over the past decade, the copper content of RAMs has halved and their tin content has increased by 70 %. The stricter environmental laws have facilitated ~96 % drop in the lead content of RAMs. To comprehend the fundamentals of thermal transformation of RAMs, our research provides their detailed kinetic study. This can assist the e-waste recyclers in optimising their metal recovery processes. Thus, understanding the chemical and thermal behaviour of RAMs can open new avenues for efficient e-waste recycling.

Keywords: electronic waste, kinetic study, recycling, thermal transformation

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Authors: Xiaoqi Jia, Qing Zhu, Hao Zhang, Su Yang

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A gender recognition system is able to tell the gender of the given person through a few of frontal facial images. An effective gender recognition approach enables to improve the performance of many other applications, including security monitoring, human-computer interaction, image or video retrieval and so on. In this paper, we present an effective method for gender classification task in frontal facial images based on deep belief networks (DBNs), which can pre-train model and improve accuracy a little bit. Our experiments have shown that the pre-training method with DBNs for gender classification task is feasible and achieves a little improvement of accuracy on FERET and CAS-PEAL-R1 facial datasets.

Keywords: gender recognition, beep belief net-works, semi-supervised learning, greedy-layer wise RBMs

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Authors: A. Nazeri, R. Ziaie Moayed, H. Ghiasinejad

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The present research has been performed to investigate the effect of base course application on load-settlement characteristics of sandy subgrade using plate load test. The main parameter investigated in this study was the subgrade reaction coefficient. The model tests were conducted in a 1.35 m long, 1 m wide, and 1 m deep steel test box of Imam Khomeini International University (IKIU Calibration Chamber). The base courses used in this research were in three different thicknesses of 15 cm, 20 cm, and 30 cm. The test results indicated that in the case of using base course over loose sandy subgrade, the values of subgrade reaction coefficient can be increased from 7  to 132 , 224 , and 396  in presence of 15 cm, 20 cm, and 30 cm base course, respectively.

Keywords: modulus of subgrade reaction, plate load test, base course, sandy subgrade

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Authors: H. Farokhi, A. Bahadoran

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This paper is focused on the absorbance and magnetic properties of a novel nanocomposite based on conducting polymer, carbon black and barium hexaferrite in epoxy resin on the E-glass fibre substrate. The highly conductive nanocomposite was provided by in-situ polymerization of aniline in the presence of carbon black (C) and barium hexaferrite (BaFe12O19) as electromagnetic absorbance material. The structure, morphology, and magnetic properties of samples were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). SEM images showed the uniformly coated PAni on the surface of carbon black and barium hexaferrite. XRD peaks also verified the presence of carbon black and barium hexaferrite in the nanocomposite. The microwave characteristics determined from the magnetic and dielectric properties of the elastomeric composites obtained from scattering data by fitting the samples in a waveguide, where measured in the frequency in X-band frequency range, the range of 8 to 12 GHz. The reflection losses were evaluated to be less than −5dB over the whole X-band frequency (8–12 GHz) for the thickness of 1.4mm.

Keywords: conductive polymer, magnetic materials, capacitance, electrochemical cell

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Authors: N. F. M. Mokhtar, N. Z. A. Hamid

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This paper reports an analytical investigation of the stability and thermal convection in a horizontal anisotropic porous medium in the presence of Coriolis force and magnetic field. The Darcy model is used in the momentum equation and Boussinesq approximation is considered for the density variation of the porous medium. The upper and lower boundaries of the porous medium are assumed to be conducting to temperature perturbation and we used first order Chebyshev polynomial Tau method to solve the resulting eigenvalue problem. Analytical solution is obtained for the case of stationary convection. It is found that the porous layer system becomes unstable when the mechanical anisotropy parameter elevated and increasing the Coriolis force and magnetic field help to stabilize the anisotropy porous medium.

Keywords: anisotropic, Chebyshev tau method, Coriolis force, Magnetic field

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Authors: Sina Ranjbar, Masakiyo Tsunoda, Mikihiko Oogane, Yasuo Ando

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We systematically investigated the exchange anisotropy for ferromagnetic Co70Fe30 and antiferromagnetic PtMn bilayer films. We focused on the relevance between the exchange bias and the composition of the Ptₓ Mn₁₋ₓ (14 < x < 22 and 45 < x < 56 at %) films, and we successfully optimized the composition. The crystal structure of the Ptₓ Mn₁₋ₓ films was FCC for 14 < x < 22 at % and FCT for 45 < x < 56 at % after annealing at 370 ◦C for 6 hours. The unidirectional anisotropy constant (Jₖ) for fcc-Pt₁₅Mn₈₅ (20 nm) and fct-Pt₄₈Mn₅₂ (20 nm) prepared under optimum conditions in composition were 0.16 and 0.20 erg/cm², respectively. Both Pt₁₅Mn₈₅ and Pt₄₈Mn₅₂ films showed a larger unidirectional anisotropy constant (Jₖ) than in other reports. They also showed a flatter surface than that of other antiferromagnetic materials. The obtained PtMn films with a large exchange anisotropy and slight roughness are useful as an antiferromagnetic layer in spintronic applications.

Keywords: antiferromagnetic material, PtMn thin film, exchange anisotropy, composition dependence

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Authors: Zilong Peng, Jun Fan

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With the improvement of the living standards, the requirement on the acoustic comfort of the vehicle interior environment is becoming higher. The rain-the-roof producing interior noise is a common phenomenon for the vehicle, which usually discourages the conversation, especially for the heavy rain. This paper presents some numerical results about the rain-the-roof noise. The impact of each water drop is modeled as a short pulse, and the excitation locations on the roof are generated randomly. The vehicle body is simplified to a box closed with some certain-thickness shells. According to the main frequency components of the rain excitation, the analyzing frequency range is divided as low, high and middle frequency domains, which makes the vehicle body are modeled using finite element method (FEM), statistical energy analysis (SEA) and hybrid FE-SEA method, respectively. Furthermore, the effect of spatial distribution density and size of the rain on the sound pressure level are also discussed. These results may provide a guide for designing a more silent vehicle in the special weather.

Keywords: rain-the-roof noise, vehicle, finite element method, statistical energy analysis

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Authors: Sophie N. Selby-Pham, Yudie Wang, Louise Bennett

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Consumption of grapes promotes health and reduces the risk of chronic diseases due to the action of grape phytochemicals in regulation of Oxidative Stress and Inflammation (OSI). The bioefficacy of phytochemicals depends on their absorption in the human body. The time required for phytochemicals to achieve maximal plasma concentration (Tₘₐₓ) after oral intake reflects the time window of maximal bioefficacy of phytochemicals, with Tₘₐₓ dependent on physicochemical properties of phytochemicals. This research collated physicochemical properties of grape phytochemicals from white and red grapes to predict their Tₘₐₓ using pharmacokinetic modelling. The predicted values of Tₘₐₓ were then compared to the measured Tₘₐₓ collected from clinical studies to determine the accuracy of prediction. In both liquid and solid intake forms, white grapes exhibit a shorter Tₘₐₓ range (0.5-2.5 h) versus red grapes (1.5-5h). The prediction accuracy of Tₘₐₓ for grape phytochemicals was 33.3% total error of prediction compared to the mean, indicating high prediction accuracy. Pharmacokinetic modelling allows prediction of Tₘₐₓ without costly clinical trials, informing dosing frequency for sustained presence of phytochemicals in the body to optimize the health benefits of phytochemicals.

Keywords: absorption kinetics, phytochemical, phytochemical absorption prediction model, Vitis vinifera

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Authors: Thanyaporn Senarai, Rapeepun Vanichviriyakit, Shinji Miyata, Chihiro Sato, Prapee Sretarugsa, Wattana Weerachatyanukul, Ken Kitajima

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In this study, we characterized a region-specific 250 kDa protein that was secreted of MSD fluid, which is believed to play dual functions in forming a spermatophoric wall for sperm physical protection, and in sperm membrane modification as part of sperm maturation process. The partial amino acid sequence and N-terminal sequencing revealed that the MSD-specific 250 kDa protein showed a high similarity with a plasma-rich protein, α-2 macroglobulin (α2M), so termed pp-α2M. This protein was a large glycoprotein contained predominantly mannose and GlcNAc. The expression of pp-α2M mRNA was detected in spermatic duct (SD), androgenic gland (AG) and hematopoietic tissue, while the protein expression was rather specific to the apical cytoplasm of MSD epithelium. The secretory pp-α2M in MSD fluid was acquired onto the MSD sperm membrane and was also found within the matrix of the acrosome. Distally, pp-α2M was removed from spermathecal sperm membrane, while its level kept constant in the sperm AC. Together the results indicate that pp-α2M is a 250 kDa region-specific secretory protein which plays roles in sperm physical protection and also acts as maturation factor in the P. pelagicus sperm.

Keywords: alpha-2 macroglobulin, blue swimming crab, sperm maturation, spermatic duct

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Authors: Sofiane Bourchak, Sébastien Bridier

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The objective of this study is to show how to calculate and map solar energy’s quantity (instantaneous and accumulated global solar radiation during the year) available on roofs in the city Aix-en-Provence which has a population of 140,000 inhabitants. The result is a geographic information system (GIS) layer, which represents hourly and monthly the production of solar energy on roofs throughout the year. Solar energy professionals can use it to optimize implementations and to size energy production systems. The results are presented as a set of maps, tables and histograms in order to determine the most effective costs in Aix-en-Provence in terms of photovoltaic power (electricity) and thermal power (hot water).

Keywords: geographic information system, photovoltaic, thermal, solar potential, solar radiation

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Authors: Jianli Dong, Fangling Xu, Gengming Huang

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Human endogenous retroviral elements (HERVs) comprise approximately 8% of the human genome. They are thought to be germline-integrated genetic remnants of retroviral infections. Although HERV sequences are highly defective, some, especially the K type (HERV-K), have been shown to be expressed and may have biological activities in the pathogenesis of cancer, chronic inflammation and autoimmune diseases. We found that HERV-K GAG and ENV proteins were strongly expressed in pleomorphic melanoma cells. We also detected a critical role of HERV-K ENV in mediating intercellular fusion and colony formation of melanoma cells. Interestingly, we found that levels of HERV-K GAG and ENV expression correlated with the activation of ERK and loss of p16INK4A in melanoma cells, and inhibition of MEK or CDK4, especially in combination, reduced HERV-K expression in melanoma cells. We also performed a reverse transcription-polymerase chain reaction (RT-PCR) assay using DNase I digestion to remove “contaminating” HERV-K genomic DNA and examined HERV-K RNA expression in plasma samples from HIV-1 infected individuals. We found a covariation between HERV-K RNA expression and CD4 cell counts in HIV-1 positive samples. Although a causal link between HERV-K activation and melanoma development, and between HERV-K activation, HIV-1 infection and CD4 cell count have yet to be determined, existing data support the further research efforts in HERV-K.

Keywords: CD4 cell, HERV-K, HIV-1, melanoma

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Authors: Elham Rouhollahi, Soheil Zorofchian Moghadamtousi, Salma Baig, Mahmood Ameen Abdulla, Zahurin Mohamed

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This study was designed to assess cutaneous wound healing potential of hexane extract of Curcuma purpurascens rhizomes (HECP). Twenty-four rats were divided into 4 groups: 1. Negative, 2. Low dose, 3. High dose and 4. Treatment, with 6 rats in each group. Full-thickness incisions with a diameter of 2 cm were made on the back of each rat. Rats were topically treated two times a day for 15 days. Group 1-4 were treated with sterile distilled water, 5% and 10% of extract and intrasite gel, respectively. Masson's trichrome and hematoxylin staining techniques are employed for histological analysis revealed strong wound healing potential closer to that of conventional drug intrasite gel. HECP significantly decreased wound area and an increase in hydroxyproline, cellular proliferation, the number of blood vessels and the level of collagen synthesis was observed. Thus, it could be concluded that HECP possesses strong wound healing potential.

Keywords: Curcuma purpurascens, wound healing, histopathology, hematoxylin staining

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Authors: H. Yousefnia, A. Golabi Dezfuli, S. Zolghadri, M. Hosntalab

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Peptide receptor radionuclide therapy is nowadays used for the treatment of various abnormalities with somatostatin receptors. In this study, 166Ho-DOTATOC was prepared and the best conditions for its radiolabeling was obtained. For this purpose, a certain of DOTATOC was added to a vial containing 166Ho. various experiments by varying ligand concentration, pH, temperature and time were performed to determine the best conditions. Radiochemical purity of the complex was assessed by instant thin layer chromatography method utilizing 0.9% NaCl as the mobile phase. 166Ho-DOTATOC was prepared with radiochemical purity of higher than 95% at the optimized condition (pH=4, temperature: 95° C, time:30 min). In 0.9% NaCl, free Ho cation was developed at Rf of 0.8 while the complex was remained at the front of the paper.

Keywords: Ho-166, neuroendocrine, octreotide, quality control

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Authors: Haralabos C. karantonis, Afroditi Michalaki

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High intakes of carbohydrates and fats have been associated with an increased risk of chronic diseases due to the role of postprandial oxidative stress. This pilot nutritional intervention aimed to examine the acute effect of consuming two different types of breadsticks prepared from durum wheat flour mixtures differing in total phenolic content on postprandial inflammatory and oxidant responses in healthy volunteers. A cross-over, controlled, and single-blind clinical trial was designed, and two isocaloric high-fat and high-carbohydrate meals were tested. Serum total, High Density Lipoprotein (HDL)- and Low Density Lipoprotein (LDL)-cholesterol, triglycerides, glucose, C-reactive protein (CRP), uric acid, plasma total antioxidant capacity, and antiplatelet activity were determined in fasting and 30, 60, and 120 min after consumption. The results showed a better postprandial HDL-cholesterol and total antioxidant activity response in the intervention group. The choice of durum wheat flours with higher phenolic content and antioxidant activity is presented as promising for human health, and clinical studies will expand to draw safer conclusions.

Keywords: antioxidant, antiplatelet, durum wheat, nutritional value

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Authors: Mounir Baccar, Imen Jmal

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Because of the rise in energy costs, thermal storage systems designed for the heating and cooling of buildings are becoming increasingly important. Energy storage can not only reduce the time or rate mismatch between energy supply and demand but also plays an important role in energy conservation. One of the most preferable storage techniques is the Latent Heat Thermal Energy Storage (LHTES) by Phase Change Materials (PCM) due to its important energy storage density and isothermal storage process. This paper presents a numerical study of the solidification of a PCM (paraffin RT27) in a rectangular thermal storage exchanger for air conditioning systems taking into account the presence of natural convection. Resolution of continuity, momentum and thermal energy equations are treated by the finite volume method. The main objective of this numerical approach is to study the effect of natural convection on the PCM solidification time and the impact of fins number on heat transfer enhancement. It also aims at investigating the temporal evolution of PCM solidification, as well as the longitudinal profiles of the HTF circling in the duct. The present research undertakes the study of two cases: the first one treats the solidification of PCM in a PCM-air heat exchanger without fins, while the second focuses on the solidification of PCM in a heat exchanger of the same type with the addition of fins (3 fins, 5 fins, and 9 fins). Without fins, the stratification of the PCM from colder to hotter during the heat transfer process has been noted. This behavior prevents the formation of thermo-convective cells in PCM area and then makes transferring almost conductive. In the presence of fins, energy extraction from PCM to airflow occurs at a faster rate, which contributes to the reduction of the discharging time and the increase of the outlet air temperature (HTF). However, for a great number of fins (9 fins), the enhancement of the solidification process is not significant because of the effect of confinement of PCM liquid spaces for the development of thermo-convective flow. Hence, it can be concluded that the effect of natural convection is not very significant for a high number of fins. In the optimum case, using 3 fins, the increasing temperature of the HTF exceeds approximately 10°C during the first 30 minutes. When solidification progresses from the surfaces of the PCM-container and propagates to the central liquid phase, an insulating layer will be created in the vicinity of the container surfaces and the fins, causing a low heat exchange rate between PCM and air. As the solid PCM layer gets thicker, a progressive regression of the field of movements is induced in the liquid phase, thus leading to the inhibition of heat extraction process. After about 2 hours, 68% of the PCM became solid, and heat transfer was almost dominated by conduction mechanism.

Keywords: heat transfer enhancement, front solidification, PCM, natural convection

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Authors: Elabed Saud

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This paper introduces the new ability of Artificial Neural Networks (ANNs) in estimating speed and controlling the separately excited DC motor. The neural control scheme consists of two parts. One is the neural estimator which is used to estimate the motor speed. The other is the neural controller which is used to generate a control signal for a converter. These two neutrals are training by Levenberg-Marquardt back-propagation algorithm. ANNs are the standard three layers feed-forward neural network with sigmoid activation functions in the input and hidden layers and purelin in the output layer. Simulation results are presented to demonstrate the effectiveness of this neural and advantage of the control system DC motor with ANNs in comparison with the conventional scheme without ANNs.

Keywords: Artificial Neural Network (ANNs), excited DC motor, convenional controller, speed Controller

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Authors: Z. Kadivar, M. Vahidinia, A. Mousavinia

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Kopet-Dagh Mountain Range is located in the north and northeast of Iran. Mozduran Formation in the east of Kopet-Dagh is mainly composed of limestone, dolomite, with shale and sandstone interbedded. Mozduran Formation is reservoir rock of the Khangiran gas field. The location of the study was east Kopet-Dagh basin (Northeast Iran) where the deliberate thickness of formation is 418 meters. In the present study, a total of 57 samples were gathered. Moreover, 100 thin sections were made out of 52 samples. According to the findings of the thin section study, 18 genera and nine species of foraminifera and algae were identified. Based on the index fossils, the age of the Mozduran Formation was identified as Upper Jurassic (Kimmerdgian-Tithonian) in the east of Kopet-Dagh basin. According to the magnetite data (total intensity and RTP map), there is a disconformity (low intensity) between the Kashaf-Rood Formation and Mozduran Formation. At the top, where among Mozduran Formation and Shurijeh Formation, is high intensity and a widespread disconformity (high intensity).

Keywords: upper jurassic, magnetometre, mozduran formation, stratigraphy

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Authors: Eman Al-khateeba, Ebaa Al-Zayadneha, Osama Al-Dalahmahb, Zeinab Alawadib, Faisal Khatiba, Randa Naffaa, Yanal Shafagoj

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The purpose of the current study was to examine the association of plasma copper and lipid concentrations with changes in cognitive function in elderly Jordanian individuals. The study population consisted of two groups; 52 subjects with dementia, and 50 controls. All individuals were screened with Mini-Mental State Examination (MMSE) and Clock drawing test (CDT).Serum copper and lipid profile were assessed in all subjects, and the results were statistically evaluated at P < 0.05 level of significance. Dementia group had 10.1 % higher copper levels than controls however the difference was not statistically significant. No significant differences could be found between the two groups in lipid profile levels. There was no significant correlation between serum copper, lipid profile and cognitive decline in elderly Jordanians. Demographic variables indicate that educational level less than 12 years and illiterate demonstrated a 3.29 fold (p=0.026) and 6.29 fold (p=0.002) increase in risk of developing dementia, respectively. While coffee intake showed a protective effect against cognitive decline with 6.25 fold lower risk with increased coffee intake.

Keywords: copper, cholesterol, dementia, Alzheimer's disease, lipid profile, coffee

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Authors: Latef M. Ali, Farah A. Abed

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In this paper, the effect of the Barium fluoride (BaF2) layer on the absorption efficiency of GaAs/InAs nanowire solar cells was investigated using the finite difference time domain (FDTD) method. By inserting the BaF2 as antireflection with the dominant size of 10 nm to fill the space between the shells of wires on the Si (111) substrate. The absorption is significantly improved due to the strong reabsorption of light reflected at the shells and compared with the reference cells. The present simulation leads to a higher absorption efficiency (Qabs) and reaches a value of 97%, and the external quantum efficiencies (EQEs) above 92% are observed. The current density (Jsc) increases by 0.22 mA/cm2 and the open-circuit voltage (Voc) is enhanced by 0.11 mV.

Keywords: nanowire solar cells, absorption efficiency, photovoltaic, band structures, fdtd simulation

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Authors: Deli Mona, Rafika Husni

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The aim of this research is to evaluate the effect of lighting distance on surface hardness of light composite resin. We held laboratory experimental research with post-test only group design. The samples used are 30 disc-like hybrid composite resins with the diameter is 6 mm and the thickness is 2 mm, lighted by an LED for 20 seconds. They were divided into 3 groups, and every group was consisted by 10 samples, which were 0 mm, 2 mm, and 5 mm lighting distance group. Every samples group was treated with hardness test, Vicker Hardness Test, then analyzed with one-way ANOVA test to evaluate the effect of lighting distance differences on surface hardness of light composite resin. Statistic test result shown hardness mean change of composite renin between 0 mm and 2 mm lighting distance with 0.00 significance (p<0.05), between 0 mm and 5 mm lighting distance with 0.00 significance (p<0.05), and 2 mm and 5 mm lighting distance with 0.05 significance (p<0.05). According to the result of this research, we concluded that the further lighting distance, the more surface hardness decline of hybrid composite resin.

Keywords: composite resin hybrid, tip distance, microhardness, light curing LED

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Authors: Nicolas Giraudo, Peter Thissen

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In this paper we bring up new aspects of the metal proton exchange reaction (MPER, also called early stage hydration): (1) its dependence of the number of protons consumed by the preferential exchanged cations on the pH value applied at the water/wollastonite interface and (2) strong anisotropic characteristics detected in atomic force microscopy (AFM) and low energy ion scattering spectroscopy measurements (LEIS). First we apply density functional theory (DFT) calculations to compare the kinetics of the reaction on different wollastonite surfaces, and combine it with ab initio thermodynamics to set up a model describing (1) the release of Ca in exchange with H coming from the water/wollastonite interface, (2) the dependence of the MPER on the chemical potential of protons. In the second part of the paper we carried out in-situ AFM and inductive coupled plasma atomic emission spectroscopy (ICP-OES) measurements in order to evaluate the predicted values. While a good agreement is found in the basic and neutral regime (pH values from 14-4), an increasing mismatch appears in the acidic regime (pH value lower 4). This is finally explained by non-equilibrium etching, dominating over the MPER in the very acidic regime.

Keywords: anisotropy, calcium silicate, cement, density functional theory, hydration

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Authors: Mohamed Hussein

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This paper studies the effect of boundary retaining walls properties on the behavior of the raft foundation. Commercial software program Sap2000 was used in this study. The soil was presented as continuous media (follows the Winkler assumption). Shell elements were employed to model the raft plate. A parametric study has been carried out to examine the effect of boundary retaining walls properties on the behavior of raft plate. These parameters namely, height of the boundary retaining walls, thickness of the boundary retaining walls, flexural rigidity of raft plate, bearing capacity of supporting soil and the earth pressure of boundary soil. The main results which were obtained from this study are positive, negative bending moment, shear stress and deflection in raft plate, where these parameters are considered the main parameters used in design of raft foundation. It was concluded that the boundary retaining walls have a significant effect on the straining actions in raft plate.

Keywords: Sap2000, boundary retaining walls, raft foundations, Winkler model, flexural rigidity

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Authors: Bandar Ali Al-Asbahi, Mohammad Hafizuddin Haji Jumali

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Forster energy transfer between poly (9,9'-di-n-octylfluorenyl-2,7-diyl) (PFO)/TiO2 nanoparticles (NPs) as a donor and Fluorol 7GA as an acceptor has been studied. The energy transfer parameters were calculated by using mathematical models. The dominant mechanism responsible for the energy transfer between the donor and acceptor molecules was Forster-type, as evidenced by large values of quenching rate constant, energy transfer rate constant and critical distance of energy transfer. Moreover, these composites which were used as an emissive layer in organic light emitting diodes, were investigated in terms of current density–voltage and electroluminescence spectra.

Keywords: energy transfer parameters, forster-type, electroluminescence, organic light emitting diodes

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Authors: Adam Abdalla Elbashir Adam, Xiaomin Cheng, Xiang Shui Miao

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In this work, the effect of the magnetron sputtering system parameters on the optical properties of the Mn doped GeTe were investigated. The optical properties of the Ge_1-xMn_xTe thin films with different thicknesses are determined by analyzing the transmittance and reflectance data. The energy band gaps of the amorphous Mn-doped GeTe thin films with different thicknesses were calculated. The obtained results demonstrated that the energy band gap values of the amorphous films are quite different and they are dependent on the films thicknesses. The extinction coefficients of amorphous Mn-doped GeTe thin films as function of wavelength for different thicknesses were measured. The results showed that the extinction coefficients of all films are varying inversely with their optical transmission. Moreover, the results emphasis that, not only the microstructure, electrical and magnetic properties of Mn doped GeTe thin films vary with the films thicknesses but also the optical properties differ with the film thickness.

Keywords: phase change magnetic materials, transmittance, absorbance, extinction coefficients

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Authors: O. Hanita, S. A. Ainnul Hamidah, A. H. Yang Zalila, M. R. Siti Nadiah, M. H. Najihah, M. A. Hapipah

Abstract:

The crude extract of the leaves of Actinodaphne sesquipedalis Hook. F. Var. Glabra (Kochummen), was taken under phytochemical investigation. The crude methanolic extract was partitioned with a different solvent system by increasing their polarities (n-hexane, dichloromethane, and methanol). The compounds were fractionated and isolated from n-hexane partition by using column chromatography with silica gel 60 or Sephadex LH-20 as a stationary phase and preparative thin layer chromatographic technique. Isolates were characterized using TLC, FTIR, UV spectrophotometer and NMR spectroscopy. The n-hexane fractionates yielded a total of four compounds namely N-methyllaurotetanine (1), dicentrine (2), β-sitosterol (3), and stigmasterol (4). The result indicates that the leaves of Actinodaphne sesquipedalis may provide a rich source of alkaloids and triterpenoids.

Keywords: actinodaphne sesquipedalis, alkaloids, phytochemical investigation, triterpenoids

Procedia PDF Downloads 383

Authors: Dwarakanadha Reddy Peram, D. Swarnalatha, C. Gopinath

Abstract:

The main aim of this research work was to design and development characterization of Pioglitazone transdermal drug delivery system by using various polymers such as Olibanum with different concentration by solvent evaporation technique. The prepared formulations were evaluated for different physicochemical characteristics like thickness, folding endurance, drug content, percentage moisture absorption, percentage moisture loss, percentage elongation break test and weight uniformity. The diffusion studies were performed by using modified Franz diffusion cells. The result of dissolution studies shows that formulation, F3 (Olibanum with 50 mg) showed maximum release of 99.95 % in 12hrs, whereas F1 (Olibanum and EC backing membrane) showed minimum release of 93.65% in 12 hr. Based on the drug release and physicochemical values obtained the formulation F3 is considered as an optimized formulation which shows higher percentage of drug release of 99.95 % in 12 hr. The developed transdermal patches increase the therapeutic efficacy and reduced toxic effect of pioglitazone.

Keywords: pioglitazone, olibanum, transdermal drug delivery system, drug release percantage

Procedia PDF Downloads 194