Search results for: broadband dielectric spectroscopy

Authors: Akim Borbuev, Francisco de León

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Economic and population growth in densely-populated urban areas introduce major challenges to distribution system operators, planers, and designers. To supply added loads, utilities are frequently forced to invest in new distribution feeders. However, this is becoming increasingly more challenging due to space limitations and rising installation costs in urban settings. This paper proposes the conversion of critical alternating current (ac) distribution feeders into direct current (dc) feeders to increase the power transfer capacity by a factor as high as four. Current trends suggest that the return of dc transmission, distribution, and utilization are inevitable. Since a total system-level transformation to dc operation is not possible in a short period of time due to the needed huge investments and utility unreadiness, this paper recommends that feeders that are expected to exceed their limits in near future are converted to dc. The increase in power transfer capacity is achieved through several key differences between ac and dc power transmission systems. First, it is shown that underground cables can be operated at higher dc voltage than the ac voltage for the same dielectric stress in the insulation. Second, cable sheath losses, due to induced voltages yielding circulation currents, that can be as high as phase conductor losses under ac operation, are not present under dc. Finally, skin and proximity effects in conductors and sheaths do not exist in dc cables. The paper demonstrates that in addition to the increased power transfer capacity utilities substituting ac feeders by dc feeders could benefit from significant lower costs and reduced losses. Installing dc feeders is less expensive than installing new ac feeders even when new trenches are not needed. Case studies using the IEEE 342-Node Low Voltage Networked Test System quantify the technical and economic benefits of dc feeders.

Keywords: DC power systems, distribution feeders, distribution networks, power transfer capacity

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Authors: Samira Gharehkhani, Seyed Farid Seyed Shirazi, Abdolreza Gharehkhani, Hooman Yarmand, Ahmad Badarudin, Rushdan Ibrahim, Salim Newaz Kazi

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Nanocrystalline cellulose (NCC) were prepared by acid hydrolysis and ultrasound treatment of bleached Acacia mangium fibers. The obtained rod-shaped nanocrystals showed a uniform size. The results showed that NCC with high crystallinity can be obtained using 64 wt% sulfuric acid. The effect of synthesis condition was investigated. Different reaction times were examined to produce the NCC and the results revealed that an optimum reaction time has to be used for preparing the NCC. Morphological investigation was performed using the transmission electron microscopy (TEM). Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA) were performed. X-ray diffraction (XRD) analysis revealed that the crystallinity increased with successive treatments. The NCC suspension was homogeneous and stable and no sedimentation was observed for a long time.

Keywords: acid hydrolysis, nanocrystalline cellulose, nano material, reaction time

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Authors: Souha Bouagila, Soufiene Ilahi, Noureddine Yacoubi

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We have used Photothermal deflection spectroscopy PTD to investigate the impact of thermal annealing on electronics properties of GaInAsSb/GaSb.GaInAsSb used as an active layer for Vertical Cavity Surface Emitting laser (VCSEL). We have remarked that surface recombination velocity (SRV) from 7963 m / s (± 6.3%) to 1450 m / s (± 3.6) for as grown to sample annealed for 60 min. Accordingly, Force Microscopy images analyses agree well with the measure of surface recombination velocity. We have found that Root-Mean-Square Roughness (RMS) decreases as respect of annealing time. In addition, we have that the diffusion length and minority carrier mobility have been enhanced according to annealing time. However, due to annealing effects, the interface recombination velocity (IRV) is increased from 1196 m / s (± 5) to 6000 m/s (5%) for GaInAsSb in respect of annealed times.

Keywords: nonradiative lifetime, mobility of minority carrier, diffusion length, Surface and interface recombination velocity

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Authors: Eduardo Padilla, Luis Daniel Rodriguez, Ivan Sanchez, Angelica Sofia Go

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The synthesis and application of metallic nanoparticles have increased in recent years. Biological methods go beyond the chemical and physical synthesis that is expensive and not friendly to the environment. Therefore, in this study, silver nanoparticles were synthesized biologically in an environmentally friendly way by Handroanthus chrysanthus flower aqueous extract (AgNPs) that contains phytochemicals capable of reducing silver nitrate. AgNPs were characterized visually by UV-visible spectroscopy and TEM. The antimicrobial activity of the AgNPs was tested by determining the minimum inhibitory concentration (MIC), and minimal bactericidal concentration (MBC) in Escherichia coli and Staphylococcus aureus strains AgNPs showed potent antimicrobial activity against gram-negative and gram-positive bacteria. MIC and MBC values were as low as 41.6, and 83.2 ug/mL using AgNPs biosynthesized by H. chrysanthus flower extract. This nanoparticle could be the basis for the formulation of disinfectants for use in the food and pharmaceutical industry.

Keywords: antimicrobial, silver nanoparticles, flower extract, Handroanthus

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Authors: Najme Lari, Shahrokh Ahangarani, Ali Shanaghi

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Sol-gel technology is a promising manufacturing method to produce anti reflective silica thin films for solar energy applications. So to improve the properties of the films, controlling parameter of the sol - gel method is very important. In this study, soaking treatment effect on optical properties of silica anti reflective thin films was investigated. UV-Visible Spectroscopy, Fourier-Transformed Infrared Spectrophotometer and Field Emission Scanning Electron Microscopy was used for the characterization of silica thin films. Results showed that all nanoporous silica layers cause to considerable reduction of light reflections compared with uncoated glasses. With single layer deposition, the amount of reduction depends on the dipping time of coating and has an optimal time. Also, it was found that solar transmittance increased from 91.5% for the bare slide up to 97.5% for the best made sample corresponding to two deposition cycles.

Keywords: sol–gel, silica thin films, anti reflective coatings, optical properties, soaking treatment

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Authors: Amrei Voelkner, Nils Peters, Thomas Mannheim

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The worldwide exponential growth of the population and the simultaneous increasing food production requires the strategic realization of sustainable and improved cultivation systems to ensure the fertility of arable land and to guarantee the food supply for the whole world. To fulfill this target, large quantities of fertilizers have to be applied to the field, but the long-term environmental impacts remain uncertain. Thus, a combined system would be necessary to increase the nutrient availability for plants while reducing nutrient losses (e.g. NO3- by leaching) to the environment. To enhance the nutrient efficiency, polymer coated fertilizer with a controlled release behavior have been developed. This kind of fertilizer ensures a delayed release of nutrients to synchronize the nutrient supply with the demand of different crops. In the last decades, research focused primarily on semi-permeable polyurethane coatings, which remain in the soil for a long period after the complete solvation of the fertilizer core. Within the implementation of the new European Regulation Directive the replacement of non-degradable synthetic polymers by degradable coatings is necessary. It was, therefore, the objective of this study to develop a total biodegradable polymer (to CO2 and H2O) coating according to ISO 17556 and to compare the retarding effect of the biodegradable coatings with commercially available non-degradable products. To investigate the effect of ten selected coated urea fertilizer on the yield of annual ryegrass and maize, the fresh and dry mass, the percentage of total nitrogen and main nutrients were analyzed in greenhouse experiments in sixfold replications using near-infrared spectroscopy. For the experiments, a homogenized and air-dried loamy sand (Cambic Luvisol) was equipped with a basic fertilization of P, K, Mg and S. To investigate the effect of nitrogen level increase, three levels (80%, 100%, 120%) were established, whereas the impact of CRF granules was determined using a N-level of 100%. Additionally, leaching of NO3- from pots planted with annual ryegrass was examined to evaluate the retention capacity of urea by the polymer coating. For this, leachate from Kick-Brauckmann-Pots was collected daily and analyzed for total nitrogen, NO3- and NH4+ in twofold repetition once a week using near-infrared spectroscopy. We summarize from the results that the coated fertilizer have a clear impact on the yield of annual ryegrass and maize. Compared to the control, an increase of fresh and dry mass could be recognized. Partially, the non-degradable coatings showed a retarding effect for a longer period, which was however reflected by a lower fresh and dry mass. It was ascertained that the percentage of leached-out nitrate could be reduced markedly. As a conclusion, it could be pointed out that the impact of coated fertilizer of all polymer types might contribute to a reduction of negative environmental impacts in addition to their fertilizing effect.

Keywords: biodegradable polymers, coating, enhanced efficiency fertilizers, nitrate leaching

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Authors: Dilip K. Paul

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The most popular mesoporous molecular sieves, Mobil Composition of Matter (MCM) are keenly studied by researchers because of these materials possess amorphous silica wall and have a long range of ordered framework with uniform mesopores. These materials also possess large surface area, which can be up to more than 1000 m2g−1. Herein the investigation is focused upon the synthesis and characterization of chromium and aluminum doped MCM-41 using XRD and FTIR. Acid-base properties of Cr-Al-MCM 41 was investigated by molecularly sensitive transmission FT-IR spectroscopy by adsorbing pyridine. In addition, these MCM nanomaterial was used to catalyze C-C bond formation from acetaldehyde adsorption. The assignment of all infrared peaks during adsorption of pyridine provided detail information on the presence of acid-base sites which in turn helped us to explain the roles of these in the condensation reaction of aldehyde. Reaction mechanisms of C-C bond formation is therefore explored to shed some light on this elusive reaction detail.

Keywords: mesoporous nanomaterial, MCM 41, FTIR studies, acid-base studies

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Authors: Emmanuel Ogundimu, Esther Akinlabi, Mutiu Erinosho

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The aim of this paper is to study the effect of welding current on the microstructure and the mechanical properties. Material characterizations were conducted on a 6 mm thick plates of type-304 austenite stainless steel, welded by TIG welding process at two different welding currents of 150 A (Sample F3) and 170 A (Sample F4). The tensile strength and the elongation obtained from sample F4 weld were approximately 584 MPa and 19.3 %; which were higher than sample F3 weld. The average microhardness value of sample F4 weld was found to be 235.7 HV, while that of sample F3 weld was 233.4 HV respectively. Homogenous distribution of iron (Fe), chromium (Cr) and nickel (Ni) were observed at the welded joint of the two samples. The energy dispersive spectroscopy (EDS) analysis revealed that Fe, Cr, and Ni made up the composition formed in the weld zone. The optimum welding current of 170 A for TIG welding of type-304 austenite stainless steel can be recommended for high-tech industrial applications.

Keywords: microhardness, microstructure, tensile, MIG welding, process, tensile, shear stress TIG welding, TIG-MIG welding

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Authors: Gerd Wilsch, Tobias Guenther, Tobias Voelker

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In view of the ageing of vital infrastructure facilities, a reliable condition assessment of concrete structures is becoming of increasing interest for asset owners to plan timely and appropriate maintenance and repair interventions. For concrete structures, reinforcement corrosion induced by penetrating chlorides is the dominant deterioration mechanism affecting the serviceability and, eventually, structural performance. The determination of the quantitative chloride ingress is required not only to provide valuable information on the present condition of a structure, but the data obtained can also be used for the prediction of its future development and associated risks. At present, wet chemical analysis of ground concrete samples by a laboratory is the most common test procedure for the determination of the chloride content. As the chloride content is expressed by the mass of the binder, the analysis should involve determination of both the amount of binder and the amount of chloride contained in a concrete sample. This procedure is laborious, time-consuming, and costly. The chloride profile obtained is based on depth intervals of 10 mm. LIBS is an economically viable alternative providing chloride contents at depth intervals of 1 mm or less. It provides two-dimensional maps of quantitative element distributions and can locate spots of higher concentrations like in a crack. The results are correlated directly to the mass of the binder, and it can be applied on-site to deliver instantaneous results for the evaluation of the structure. Examples for the application of the method in the laboratory for the investigation of diffusion and migration of chlorides, sulfates, and alkalis are presented. An example for the visualization of the Li transport in concrete is also shown. These examples show the potential of the method for a fast, reliable, and automated two-dimensional investigation of transport processes. Due to the better spatial resolution, more accurate input parameters for model calculations are determined. By the simultaneous detection of elements such as carbon, chlorine, sodium, and potassium, the mutual influence of the different processes can be determined in only one measurement. Furthermore, the application of a mobile LIBS system in a parking garage is demonstrated. It uses a diode-pumped low energy laser (3 mJ, 1.5 ns, 100 Hz) and a compact NIR spectrometer. A portable scanner allows a two-dimensional quantitative element mapping. Results show the quantitative chloride analysis on wall and floor surfaces. To determine the 2-D distribution of harmful elements (Cl, C), concrete cores were drilled, split, and analyzed directly on-site. Results obtained were compared and verified with laboratory measurements. The results presented show that the LIBS method is a valuable addition to the standard procedures - the wet chemical analysis of ground concrete samples. Currently, work is underway to develop a technical code of practice for the application of the method for the determination of chloride concentration in concrete.

Keywords: chemical analysis, concrete, LIBS, spectroscopy

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Authors: Surjyakanta Rana, Sreekantha B. Jonnalagadda

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Synthesis of well distributed Pd nanoparticles (3 – 7 nm) on organo amine-functionalized graphene is reported, which demonstrated excellent catalytic activity towards Suzuki coupling reaction. The active material was characterized by X-ray diffraction (XRD), BET surface area, X-ray photoelectron spectra (XPS), Fourier-transfer infrared spectroscopy (FTIR), Raman spectra, Scanning electron microscope (SEM), Transmittance electron microscopy (TEM) analysis and HRTEM. FT-IR revealed that the organic amine functional group was successfully grafted onto the graphene oxide surface. The formation of palladium nanoparticles was confirmed by XPS, TEM and HRTEM techniques. The catalytic activity in the coupling reaction was superb with 100% conversion and 98 % yield and also activity remained almost unaltered up to six cycles. Typically, an extremely high turnover frequency of 185,078 h-1 is observed in the C-C Suzuki coupling reaction using organo di-amine functionalized graphene as catalyst.

Keywords: Di-amine, graphene, Pd nanoparticle, suzuki coupling

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Authors: A. Saurabh Singh, B. Raghvendra, C. Prabhakar Singh

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Solid Oxide Fuel Cells (SOFCs) are one of the most attractive electrochemical energy conversion systems, as these devices present a clean energy production, thus promising high efficiencies and low environmental impact. The electrodes are the main components that decisively control the performance of a SOFC. Conventional, anode materials (like Ni-YSZ) are operates at very high temperature. Therefore, cost-effective materials which operate at relatively lower temperatures are still required. In present study, we have synthesized La doped Strontium Titanate via solid state reaction route. The structural, microstructural and density of the pellet have been investigated employing XRD, SEM and Archimedes Principle, respectively. The electrical conductivity of the systems has been determined by impedance spectroscopy techniques. The electrical conductivity of the Lanthanum Strontium Titanate (LST) has been found to be higher than the composite Ni-YSZ system at 700 °C.

Keywords: IT-SOFC, LST, Lanthanum Strontium Titanate, electrical conductivity

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Authors: Darren A. Whitaker, Dan Palmer, Jens Wesholowski, James Flaherty, John Mack, Ahmad B. Albadarin, Gavin Walker

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Traditional mechanosynthesis has been performed by either ball milling or manual grinding. However, neither of these techniques allow the easy application of process control. The temperature may change unpredictably due to friction in the process. Hence the amount of energy transferred to the reactants is intrinsically non-uniform. Recently, it has been shown that the use of Twin-Screw extrusion (TSE) can overcome these limitations. Additionally, TSE enables a platform for continuous synthesis or manufacturing as it is an open-ended process, with feedstocks at one end and product at the other. Several materials including metal-organic frameworks (MOFs), co-crystals and small organic molecules have been produced mechanochemically using TSE. The described advantages of TSE are offset by drawbacks such as increased process complexity (a large number of process parameters) and variation in feedstock flow impacting on product quality. To handle the above-mentioned drawbacks, this study utilizes UV-Vis spectrophotometry (InSpectroX, ColVisTec) as an online tool to gain real-time information about the quality of the product. Additionally, this is combined with real-time process information in an Advanced Process Control system (PharmaMV, Perceptive Engineering) allowing full supervision and control of the TSE process. Further, by characterizing the dynamic behavior of the TSE, a model predictive controller (MPC) can be employed to ensure the process remains under control when perturbed by external disturbances. Two reactions were studied; a Knoevenagel condensation reaction of barbituric acid and vanillin and, the direct amidation of hydroquinone by ammonium acetate to form N-Acetyl-para-aminophenol (APAP) commonly known as paracetamol. Both reactions could be carried out continuously using TSE, nuclear magnetic resonance (NMR) spectroscopy was used to confirm the percentage conversion of starting materials to product. This information was used to construct partial least squares (PLS) calibration models within the PharmaMV development system, which relates the percent conversion to product to the acquired UV-Vis spectrum. Once this was complete, the model was deployed within the PharmaMV Real-Time System to carry out automated optimization experiments to maximize the percentage conversion based on a set of process parameters in a design of experiments (DoE) style methodology. With the optimum set of process parameters established, a series of PRBS process response tests (i.e. Pseudo-Random Binary Sequences) around the optimum were conducted. The resultant dataset was used to build a statistical model and associated MPC. The controller maximizes product quality whilst ensuring the process remains at the optimum even as disturbances such as raw material variability are introduced into the system. To summarize, a combination of online spectral monitoring and advanced process control was used to develop a robust system for optimization and control of two TSE based mechanosynthetic processes.

Keywords: continuous synthesis, pharmaceutical, spectroscopy, advanced process control

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Authors: R. R. Galiev, I. I. Lykov, A. E. Shitikov, I. A. Bilenko

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Dual-comb interferometry is based on the mixing of two optical frequency combs with slightly different lines spacing which results in the mapping of the optical spectrum into the radio-frequency domain for future digitizing and numerical processing. The dual-comb approach enables diverse applications, including metrology, fast high-precision spectroscopy, and distance range. Ordinary frequency-modulated continuous-wave (FMCW) laser-based Light Identification Detection and Ranging systems (LIDARs) suffer from two main disadvantages: slow and unreliable mechanical, spatial scan and a rather wide linewidth of conventional lasers, which limits speed measurement resolution. Dual-comb distance measurements with Allan deviations down to 12 nanometers at averaging times of 13 microseconds, along with ultrafast ranging at acquisition rates of 100 megahertz, allowing for an in-flight sampling of gun projectiles moving at 150 meters per second, was previously demonstrated. Nevertheless, pump lasers with EDFA amplifiers made the device bulky and expensive. An alternative approach is a direct coupling of the laser to a reference microring cavity. Backscattering can tune the laser to the eigenfrequency of the cavity via the so-called self-injection locked (SIL) effect. Moreover, the nonlinearity of the cavity allows a solitonic frequency comb generation in the very same cavity. In this work, we developed a fully integrated, power-efficient, electrically driven dual-micro comb source based on the semiconductor lasers SIL to high-quality integrated Si3N4 microresonators. We managed to obtain robust 1400-1700 nm combs generation with a 150 GHz or 1 THz lines spacing and measure less than a 1 kHz Lorentzian withs of stable, MHz spaced beat notes in a GHz band using two separated chips, each pumped by its own, self-injection locked laser. A deep investigation of the SIL dynamic allows us to find out the turn-key operation regime even for affordable Fabry-Perot multifrequency lasers used as a pump. It is important that such lasers are usually more powerful than DFB ones, which were also tested in our experiments. In order to test the advantages of the proposed techniques, we experimentally measured a minimum detectable speed of a reflective object. It has been shown that the narrow line of the laser locked to the microresonator provides markedly better velocity accuracy, showing velocity resolution down to 16 nm/s, while the no-SIL diode laser only allowed 160 nm/s with good accuracy. The results obtained are in agreement with the estimations and open up ways to develop LIDARs based on compact and cheap lasers. Our implementation uses affordable components, including semiconductor laser diodes and commercially available silicon nitride photonic circuits with microresonators.

Keywords: dual-comb spectroscopy, LIDAR, optical microresonator, self-injection locking

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Authors: Josef Sepitka, Petr Vlcak, Tomas Horazdovsky, Vratislav Perina

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An ion implantation technique was used for designing the surface area of a titanium alloy and for irradiation-enhanced hardening of the surface. The Ti6Al4V alloy was treated by nitrogen ion implantation at fluences of 2·10¹⁷ and 4·10¹⁷ cm^-2 and at ion energy 90 keV. The depth distribution of the nitrogen was investigated by Rutherford Backscattering Spectroscopy. The gradient of mechanical properties was investigated by nanoindentation. The continuous measurement mode was used to obtain depth profiles of the indentation hardness and the reduced storage modulus of the modified surface area. The reduced storage modulus and the hardness increase with increasing fluence. Increased fluence shifts the peak of the mechanical properties as well as the peak of nitrogen concentration towards to the surface. This effect suggests a direct relationship between mechanical properties and nitrogen distribution.

Keywords: nitrogen ion implantation, titanium-based nanolayer, storage modulus, hardness, microstructure

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Authors: Devender Mandala, Paul Watts

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Cis-Nucleosides mainly lamivudine (3TC) and emtricitabine (FTC) are an important tool in the treatment of Human immune deficiency virus (HIV), Hepatitis B virus (HBV) and Human T-Lymotropoic virus (HTLV). Lamivudine and emtricitabine are potent nucleoside analog reverse transcriptase inhibitors (nRTI). These two drugs are synthesized by a four-stage process from the starting materials: menthyl glyoxylate hydrate and 1,4-dithane-2,5-diol to produce the 5-hydroxy oxathiolane which upon acetylation with acetic anhydride to yield 5-acetoxy oxathiolane. Then glycosylation of this acetyl product with silyl protected nucleoside to produce the intermediate. The reduction of this intermediates can provide the final targets. Although there are several different methods reported for the synthesis of lamivudine and emtricitabine as a single enantiomer, we required an efficient route, which was suitable for large-scale synthesis to support the development of these compounds. In this process, we successfully prepared the intermediates of lamivudine and emtricitabine without using any solvents and catalyst, thus promoting the green synthesis. All the synthesized compound were confirmed by TLC, GC, Mass, NMR and 13C NMR spectroscopy.

Keywords: emtricitabine, green synthesis, lamivudine, nucleoside

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Authors: Ghazi Faisal Najmuldeen, Noridah Abdullah, Mimi Sakinah

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Bioethanol is an alcohol made by fermentation, mostly from carbohydrates, Cellulosic biomass, derived from non-food sources, such as castor shell waste, is also being developed as a feedstock for ethanol production Cellulose extracted from biomass sources is considered the future feedstock for many products due to the availability and eco-friendly nature of cellulose. In this study, castor shell (CS) biowaste resulted from the extraction of Castor oil from castor seeds was evaluated as a potential source of cellulose. The cellulose was extracted after pretreatment process was done on the CS. The pretreatment process began with the removal of other extractives from CS, then an alkaline treatment, bleaching process with hydrogen peroxide, and followed by a mixture of acetic and nitric acids. CS cellulose was analysed by infrared absorption spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The result showed that the overall process was adequate to produce cellulose with high purity and crystallinity from CS waste. The cellulose was then hydrolyzed to produce glucose and then fermented to bioethanol.

Keywords: bioethanol, castor shell, cellulose, biowaste

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Authors: Augusto P. Andrade, Pedro L. Guedes, Pedro T. Da Silva, Liliane Ventura

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The present study evaluates the contribution of sunglasses frames as additional eye safety for ultraviolet backscatter light. Current sunglasses standards establish safe limits regarding lens transmittance in the 280 nm to 380 nm range. However, frames are additionally relevant in protecting the eyes from ultraviolet exposure. This study involves the use of a prototype that simulates backscattered light environments and quantifies the contribution of the frame as a function of the light that reaches the eye when wearing sunglasses. The prototype consists of an LED illuminated sphere, a mannequin head with optical sensors, and baseline and measurements are performed. A set of 29 samples was tested, and results show the variation of light blocking presented by different types of frames, ranging from 68% to 80%. This is still ongoing research. Prototype improvements for allowing albedo simulation, as well as the six types of sky simulation, are being implemented to show the intensity of UV light reaching the eye for several environments worldwide.

Keywords: sunglasses standards, sunglasses frame, ultraviolet protection, albedo

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Authors: D. S. Vardar, A. S. Kipcak, F. T. Senberber, E. M. Derun, S. Piskin, N. Tugrul

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Zinc borate is an important inorganic hydrate borate material, which can be use as a flame retardant agent and corrosion resistance material. This compound can loss its structural water content at higher than 290°C. Due to thermal stability; Zinc Borate can be used as flame reterdant at high temperature process of plastic and gum. In this study, the ultrasonic reaction of zinc borates were studied using hydrozincite (Zn5(CO3)2•(OH)6) and boric acid (H3BO3) raw materials. Before the synthesis raw materials were characterized by X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR). Ultrasonic method is a new application on the zinc borate synthesis. The synthesis parameters were set to 90°C reaction temperature and 55 minutes of reaction time, with 1:1, 1:2, 1:3, 1:4 and 1:5 molar ratio of starting materials (Zn5(CO3)2•(OH)6 : H3BO3). After the zinc borate synthesis, the products analyzed by XRD and FT-IR. As a result, optimum molar ratio of 1:5 (Zn5(CO3)2•(OH)6:H3BO3) is determined for the synthesis of zinc borates with ultrasonic method.

Keywords: borate, ultrasonic method, zinc borate, zinc borate synthesis

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Authors: Ruitao Li, Zhili Dong, Nay Win Khun, Khiam Aik Khor

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In this study, microstructure and sintering mechanism as well as wear resistance properties of Ti/Al-Cr-Fe metal matrix composites (MMCs) fabricated by spark plasma sintering (SPS) with Ti as matrix and Al-Cr-Fe as reinforcement were investigated. Phases and microstructure of the sintered samples were analyzed using X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and transmission electron microscopy (TEM). Wear resistance properties were tested by ball-on-disk method. An Al3Ti ring forms around each Al-Cr-Fe particle as the bonding layer between Ti and Al-Cr-Fe particles. The Al content in Al-Cr-Fe particles experiences a decrease from 70 at.% to 60 at.% in the sintering process. And these particles consist of quasicrystalline icosahedral AlCrFe and quasicrystal approximants γ-brass Al8(Cr,Fe)5 and Al9(Cr,Fe)4 in the sintered compact. The addition of Al-Cr-Fe particles into the Ti matrix can improve the microhardness by about 40% and the wear resistance is improved by more than 50% due to the increase in the microhardness and the change of wear mechanism.

Keywords: metal matrix composites, spark plasma sintering, phase transformation, wear

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Authors: Zohreh Derikvand

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Nanoreactors Zr-MCM-41were prepared via the reaction of ZrOCl2, Fumed silica, sodium hydroxide and cethyltrimethyl ammonium bromide under hydrothermal condition. The prepared nanoreactors were characterized by FT-IR spectroscopy, X-ray diffraction (XRD), Scanning electron micrographs (SEM) and nitrogen adsorption-desorption. The XRD pattern of Zr-MCM-41 exhibits a high-intensity (100) and two low-intensity reflections (110 and 200) which are characteristic of hexagonal structure, exhibiting the long-range order and good textural uniformity of mesoporous structure. Based on the green chemistry approach, we report an efficient and environmentally benign protocol to study the catalytic activity of Zr-MCM-41 in the Biginelli type reactions initially. Nanoreactors Zr-MCM-41 were used as highly recoverable and reusable catalyst for synthesis of 3,4-dihydropyrimidin-2(1H)-one, octahydroquinazolinone, benzimidazolo-quinazolineone and 4,6-diarylpyrimidin-2(1H)-one. The methodology offers several advantages such as short reaction time, high yields and simple operation. The catalyst was active up to three cycles.

Keywords: Zr-MCM-41 nanoreactors, Biginelli like reactions, 3, 4-dihydropyrimidin-2(1H)-ones, ctahydroquinazolinones

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Authors: Hikmet Cicek

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Transition metal nitrides are widely used as protective coatings on machine parts and cutting tools to protect the surfaces from abrasion and corrosion for decades. In this study, the ternary TiNbVN thin coatings were produced with closed field unbalanced magnetron sputtering system and their structural, mechanical and fatigue-like (multi-pass scratch test) properties were investigated. Two different substrates (M2 and H13 steels) were used to explore substrates effects. X-Ray diffractometer, scanning electron microscope, and energy dispersive spectroscopy were used for the structural and chemical analysis of the coatings. Nanohardness tests were proceed for mechanical properties. The fatigue-like properties of the coatings obtained from the multi-scratch test under three different cycle passes. The results showed that TiNbVN films have excellent fatigue resistance and the coatings deposited on M2 steel substrate have higher hardness and better fatigue resistance.

Keywords: physical vapor deposition, fatigue, metal nitride, multipass scratch test

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Authors: Ismail Seckin Cardakli, Mustafa Engin Kocadagistan, Ersin Arslan

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In this study, mechanochemical behaviour of aluminium - boron oxide - melamine ternary system was investigated by high energy ball milling. According to the reaction Al + B₂O₃ = Al₂O₃ + B, stochiometric amount of aluminium and boron oxide with melamine up to ten percent of total weight was used in the experiments. The powder characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM) after leaching of product by 1M HCl acid. Results show that mechanically induced self-sustaining reaction (MSR) between aluminium and boron oxide takes place after four hours high energy ball milling. Al₂O₃/h-BN composite powder is obtained as the product of aluminium - boron oxide - melamine ternary system.

Keywords: high energy ball milling, hexagonal boron nitride, mechanically induced self-sustaining reaction, melamine

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Authors: N. Tugrul, F. T. Senberber, A. S. Kipcak, E. Moroydor Derun, S. Piskin

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In this research, it is aimed not only microwave synthesis of magnesium borates but also evaluation of magnesium wastes. Synthesis process can be described with the reaction of Mg wastes and boric acid using microwave energy. X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR) were applied to synthesized minerals. According to XRD results, magnesium borate hydrate mixtures were obtained as mcallisterite (pdf# = 01-070-1902, Mg2(B6O7(OH)6)2.9(H2O)) at higher crystallinity properties was achieved at the mole ratio raw material 1:1. Also, other kinds of magnesium borate hydrates were obtained at lower crystallinity such as admontite (pdf # = 01-076-0540, MgO(B2O3)3.7(H2O)), inderite (pdf # = 01-072-2308, 2MgO.3B2O3.15(H2O)) and magnesium borate hydrates (pdf # = 01-076-0539, MgO(B2O3)3.6(H2O)). FT-IR spectrums indicated that minor changes were seen at the band values of characteristic stretching in each experiment. At the end of experiments it is seen that using microwave energy may contribute positive effects to design of synthesis process such as reducing reaction time and products at higher crystallinity.

Keywords: magnesium wastes, boric acid, magnesium borate, microwave energy

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Authors: Dalila Hocine, Mohammed Said Belkaid, Abderahmane Moussi

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In this study, pure rutile TiO2 thin films were directly synthesized on silicon substrates by Atmospheric Pressure Chemical Vapor Deposition technique (APCVD) using TiCl4 as precursor. We studied the physicochemical properties and the optical properties of the produced coatings by means of standard characterization techniques of Fourier Transform Infrared Spectroscopy (FTIR) combined with UV-Vis Reflectance Spectrophotometry. The absorption peaks at 423 cm-1 and 610 cm-1 were observed for the rutile TiO2 thin films, by FTIR measurements. The absorption peak at 739 cm-1 due to the vibration of the Ti-O bonds, was also detected. UV-Vis Reflectance Spectrophotometry is employed for measuring the optical band gap from the measurements of the TiO2 films reflectance. The optical band gap was then extracted from the reflectance data for the TiO2 sample. It was estimated to be 3.05 eV which agrees with the band gap of commercial rutile TiO2 sample.

Keywords: titanium dioxide, physicochemical properties, APCVD, FTIR, band gap

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Authors: Vishakha Parihar

Abstract:

This study reports the preparation of iron metal-doped nanoparticles of Titanium dioxide by the sol-gel process and the photocatalytic degradation of dye. Nano-particles were characterized by SEM, EDX, and UV-Vis spectroscopy. The detailed study confirmed that nanoparticles have grown in high density and have good optical properties. The photocatalytic batch experiment was performed in an aqueous solution where congo red dye was used as a dye pollutant under the irradiation of ultraviolet rays created by using a mercury lamp source. Total degradation efficiency achieved was approximately 85% to 93% in the duration of 100-120 minutes of irradiation under an ultraviolet light source. The decolorization ability of this process was measured by absorbance at a maximum wavelength of 498nm. The results indicated that the iron-doped Titanium dioxide nanoparticles showed an excellent photocatalytic response to the degradation of dye under the ultraviolet light source within a very short period of time.

Keywords: titanium dioxide, nano-particles iron dope, photocatalytic degradation, Congo red dye, sol-gel process

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Authors: Faroojan Khajeek Sisak Siakian, Aayda Dikran Abdulahad

Abstract:

The Peris Mountain is one of the main mountains in the Iraqi Kurdistan Region, it forms one of the long anticlines trending almost East – West. The exposed formations on the top of the mountain are Bekhme, and Shiranish, with carbonate rocks of different types and thicknesses. We selected the site for sampling to be relevant for a quarry taking into consideration the thickness of the exposed rocks, no overburden, favorable quarrying faces, hardness of the rocks, bedding nature, good extension of the outcrops, and a favorable place for construction of a cement plant. We sampled the exposed rocks on the top of the mountain where a road crosses the mountain, and a total of 15 samples were collected. The distance between sampling intervals was 5 m, and each sample was collected to represent the sampling interval. The samples were subjected to X-ray fluorescence spectroscopy (XRF) to indicate the main oxides percentages in each sample. The acquired results showed the studied rocks can be used in the cement industry.

Keywords: limestone, quarry, CaO, MgO, overburden

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Authors: Mohamed A. Deyab, Ahmed E. Awadallah

Abstract:

Under various conditions, we present a promising method for producing pure hydrogen energy from the electrochemical reaction of Mg metal in waste oilfield water (WOW). Mg metal and WOW are primarily consumed in this process. The results show that the hydrogen gas output is highly dependent on temperature and solution pH. The best conditions for hydrogen production were found to be a low pH (2.5) and a high temperature (338 K). For the first time, the Allyl methylimidazolium bis-trifluoromethyl sulfonyl imide) (IL) ionic liquid is used to regulate the rate of hydrogen generation. It has been confirmed that increasing the solution temperature and decreasing the solution pH accelerates Mg dissolution and produces more hydrogen per unit of time. The adsorption of IL on the active sites of the Mg surface is unrestricted by mixing physical and chemical orientation. Inspections using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and FT-IR spectroscopy were used to identify and characterise surface corrosion of Mg in WOW. This process is also completely safe and can create energy on demand.

Keywords: hydrogen production, Mg, wastewater, ionic liquid

Procedia PDF Downloads 139

Authors: Waqas A. Toor, Anis U. Baig, Nuaman Shafqat, Raafia Irfan, Muhammad Ashraf

Abstract:

A 2.45GHz microwave plasma system and its few applications have been developed. Argon and helium plasma is produced by metallic nozzle and also in a quartz tube at atmospheric pressure, using WR-340 waveguide and its tapered version. The waveguide applicator is also simulated in HFSS and field patterns are analyzed for maximum power absorption in the load. The system is tuned to operate at less than 10% reflected power. Various experimental techniques are used to initiate and sustain the plasma at atmospheric pressure. Plasma of atmospheric air is also produced without using any other shielding gas. The plasma flame is also characterized by its spectrum. Spectral analyses of plasma flame can be used for online analysis of combustion gases produced in industry. The applications of the system include glass and quartz processing, vitrification, emission spectroscopy, plasma coating. Low pressure plasma applications of the system include intense UV light for water purification and ozone generation.

Keywords: HFSS high frequency structure simulator, Microwave plasma, UV ultraviolet, WR rectangular waveguide

Procedia PDF Downloads 249

Authors: Shailendra Kumar, Lokesh Kashyap, Puneet Khanna, Nishant Patel, Rakesh Kumar, Arshad Ayub, Kelika Prakash, Yudhyavir Singh, Krithikabrindha V.

Abstract:

Introduction: Spinal anesthesia is considered a standard anesthesia technique for caesarean delivery. The incidence of spinal hypotension during caesarean delivery is 70 -80%. Spinal hypotension may cause cerebral hypoperfusion in the mother, but physiologically cerebral autoregulatory mechanisms accordingly prevent cerebral hypoxia. Cerebral blood flow remains constant in the 50-150 mmHg of Cerebral Perfusion Pressure (CPP) range. Near-infrared spectroscopy (NIRS) is a non-invasive technology that is used to detect Cerebral Desaturation Events (CDEs) immediately compared to other conventional intraoperative monitoring techniques. Objective: The primary aim of the study is to correlate the change in cerebral oxygen saturation using NIRS with respect to a fall in mean blood pressure after spinal anaesthesia and to find out the effects of spinal hypotension on neonatal APGAR score, neonatal acid-base variations, and presence of Postoperative Delirium (POD). Methodology: NIRS sensors were attached to the forehead of all the patients, and their baseline readings of cerebral oxygenation on the right and left frontal regions and mean blood pressure were noted. Subarachnoid block was given with hyperbaric 0.5% bupivacaine plus fentanyl, the dose being determined by the individual anaesthesiologist. Co-loading of IV crystalloid solutions was given to the patient. Blood pressure reading and cerebral saturation were recorded every 1 minute till 30min. Hypotension was a fall in MAP less than 20% of the baseline values. Patients going for hypotension were treated with an IV Bolus of phenylephrine/ephedrine. Umbilical cord blood samples were taken for blood gas analysis, and neonatal APGAR was noted by a neonatologist. Study design: A prospective observational study conducted in a population of Thirty ASA 2 and 3 parturients scheduled for lower segment caesarean section (LSCS). Results: Mean fall in regional cerebral saturation is 28.48 ± 14.7% with respect to the mean fall in blood pressure 38.92 ± 8.44 mm Hg. The correlation coefficient between fall in saturation and fall in mean blood pressure is 0.057, and p-value {0.7} after subarachnoid block. A fall in regional cerebral saturation occurred 2±1 min before a fall in mean blood pressure. Twenty-nine out of thirty patients required vasopressors during hypotension. The first dose of vasopressor requirement is needed at 6.02±2 min after the block. The mean APGAR score was 7.86 and 9.74 at 1 and 5 min of birth, respectively, and the mean umbilical arterial pH of 7.3±0.1. According to DRS-98 (Delirium Rating Scale), the mean delirium rating score on postoperative day 1 and day 2 were 0.1 and 0.7, respectively. Discussion: There was a fall in regional cerebral oxygen saturation, which started before with respect to a significant fall in mean blood pressure readings but was statistically not significant. Maximal fall in blood pressure requiring vasopressors occurs within 10 min of SAB. Neonatal APGAR scores and acid-base variations were in the normal range with maternal hypotension, and there was no incidence of postoperative delirium in patients with post-spinal hypotension.

Keywords: cerebral oxygenation, LSCS, NIRS, spinal hypotension

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Authors: Khusboo Agrawal, S. Saraf

Abstract:

Quercetin, a flavonol provides a cellular protection against UV induced oxidative damages due to its excellent free radical scavenging activity and direct pro-apoptopic effect on tumor cells. However, its topical use is limited due to its unfavorable physicochemical properties. The present study was aimed to evaluate the potential of mesoporous silica nanoparticles as topical carrier system for quercetin delivery. Complexes of quercetin with mesoporous silica was prepared with different weight ratios and characterized by thermo gravimetric analysis, X-ray diffraction, high resolution TEM, FT-IR spectroscopy, zeta potential measurements and differential scanning calorimetry The protective effect of this vehicle on UV-induced degradation of the quercetin was investigated revealing a certain positive influence of the inclusion on the photostability over time. Epidermal accumulation and transdermal permeation of this molecule were ex vivo evaluated by using Franz diffusion cells. The immobilization of Quercetin in mesoporous silica nanoparticles (MSNs) increased the stability without undermining the antioxidant efficacy.

Keywords: cancer, MSNs, quercetin, topical delivery

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