Showing papers in "Advanced Materials Research in 2015"
TL;DR: A review of polycaprolactone, an aliphatic polyester and biocompatible thermoplastic, can be found in this article, where the authors provide information on current PCL development, material properties of PCL and its composites, and also its wide spectrum applications.
Abstract: The concept of biodegradable plastics is of considerable interest with respect to solid waste accumulation. Greater efforts have been made in developing degradable biological materials without any environmental pollution to replace the traditional plastics. Among numerous kinds of degradable polymers, polycaprolactone sometimes called PCL, an aliphatic polyester and biocompatible thermoplastic, is currently a most promising and popular material with the brightest development prospect and was considered as the ‘green’ eco friendly material. The application for this biodegradable plastic includes controlled drug releases, tissue engineering, bone scaffolds, packaging and, compost bags etc. This review will provide information on current PCL development, material properties of PCL and its composites, and also its wide spectrum applications.
115 citations
TL;DR: In this article, the specific surface area of electrodes as a function the electrode structural parameters obtained from the X-ray diffraction data, and duration of activation time employed during the electrode preparation.
Abstract: Interest in research of supercapacitor has been in increasing trend because of high demand of supercapacitor application as energy storage device in both systems that require low and high power-energy usage. For supercapacitor using porous carbon electrodes, the energy storage mechanism involves the electrolyte ions in electrodes pores and electronic charges in electrodes to form electric double layers at the electrode-electrolyte interface without undergoes any chemical reaction. The specific surface area of porous electrodes, which affect the performance of supercapacitor, have been widely investigated by many researchers using the nitrogen adsorption-desorption measurement. However, despite its simplicity the X-ray diffraction method is rarely found being used to determine the specific surface area of porous electrodes. Therefore, in the present paper, we propose a new equation which expressed the specific surface area of electrodes as a function the electrode structural parameters obtained from the X-ray diffraction data, and duration of activation time employed during the electrode preparation. This equation is found to produce a satisfactory result and is expected to be beneficial for studying supercapacitor electrode materials.
40 citations
TL;DR: In this paper, 10% of cement was replaced by the calcium carbonate (CaCO3) in a study, which has a finer particles size as compared to the cement particles.
Abstract: The continued growth of the world construction sectors has resulted in high demand for concrete materials. The innovation of using filler as a replacement for cement is becoming a trend in order to reduce the cement consumption and provide benefit in various ways. Hence forth, 10% of cement was replaced by the calcium carbonate (CaCO3) in this study. CaCO3 is a natural material, which has a finer particles size as compared to the cement particles. This improves particle packing of concrete and give spacer effect. The concrete with CaCO3 replacement possess a higher slump, which increased the workability. The specimens were prepared in 150mm x 150mm x 150mm mould. At 28 days, the water absorbed by hardened concrete was lower for CaCO3 as microscopy analysis indicates very low porosity in CaCO3 concrete. Mechanical properties tests were conducted in 3, 7 and 28 days. The CaCO3 helps to increase the early strength, due to the accelerator effect and high rate of hydration which hardens the concrete quicker. At matured age, the concrete with the CaCO3 addition exhibits lower strength as compared with concrete without CaCO3, but still within the target strength.
35 citations
TL;DR: In this article, the structural and ionic conductivity of carboxymethyl cellulose - ammonium chloride as proton conducting polymer electrolytes was investigated via FTIR studies.
Abstract: The present study aims to investigate the structural and ionic conductivity of carboxymethyl cellulose - ammonium chloride as proton conducting polymer electrolytes. The complexion of polymer electrolyte films has been confirmed via FTIR studies. The conductivity enhancement with the addition of ammonium chloride concentration was proved due to the increase in amorphous nature of the films as evidenced by XRD analysis. Impedance studies indicate that the highest ionic conductivity of 1.43 x 10-3 Scm-1 was observed with the addition of 16 wt.% ammonium chloride in polymer electrolyte system obtained at ambient temperature.
33 citations
TL;DR: In this article, the impact load test results of two different impact load tests carried out on a drop-weight test machine are presented in order to evaluate the resistance of fiber reinforced concrete to impact loads.
Abstract: Fibre-reinforced composite materials are becoming important in many areas of technological application. In addition to the static load, such structures may be stressed with short-term dynamic loads or even dynamic impact loads during their lifespan. Impact loading of structural components produces a complex process, where both the characteristics of the design itself and the material parameters influence the resultant behavior. It is clear that fibre reinforced concrete has a positive impact on increasing of the resistance to impact loads. Results of two different impact load tests carried out on drop-weight test machine are presented in this report.
32 citations
TL;DR: In this article, an initial study on modifying 80/100 penetration grade bitumen with Graphite oxide (GO) prepared by using Simplified Room Temperature Hummer's process is presented.
Abstract: Graphene because of its higher surface area, strength, thinness and high electric conductivity has diversified uses from mechanical, electrical to bio medical engineering. This paper presents an initial study on modifying 80/100 penetration grade bitumen with Graphite oxide (GO) prepared by using Simplified Room Temperature Hummer’s process. The concept of utilizing GO for modification is adopted in order to improve the stiffness of the binder which can be helpful in reducing rutting potential of the pavement and to have electro thermal conductivity in modified binder, thus can be used during pavement remediation work. The limited trial rheological results obtained for 0.1125 wt. % GO modified bitumen and 0.225 wt. % GO modified bitumen showed that modification of bitumen with GO has improved its elastic capacity at higher temperature and lower frequency regime thus successfully can be used as bitumen modifier in future.
28 citations
TL;DR: In this article, simple preparation of nanocellulose particles by using ionic liquid has been introduced by investigating the influence of reaction temperature (room temperature and heat treated at 90°C).
Abstract: In recent decades, dependence on fossil fuels resources has shifted into derivation of cellulose based materials to replace the non-renewable resources. Lignocellulosic biomass is the most abundant feedstock on earth and is one of the promising renewable and sustainable resources. In the present study, simple preparation of nanocellulose particles by using ionic liquid (1-butyl-3-methylimidazolium hydrogen sulfate) has been introduced by investigating the influence of reaction temperature (room temperature and heat treated at 90°C). The resultant samples were characterized using X-Ray Diffraction (XRD) and Fourier-Transform Infrared Spectroscopy (FTIR). Interestingly, it was found that the high crystallinity sample could be synthesized at temperature of 90°C. The reason might be attributed to ionic liquid enter into the space between cellulose chains and caused cellulose molecules progressively swelled up when heated. Consequently, amorphous regions of cellulose were dissolved by ionic liquid and crystalline parts of cellulose were leave in the cellulose structure. From the XRD data, it could be observed that sharper crystalline peak and higher crystallinity index (CrI) present within heat-treated samples which corresponded to higher crystalline structure of cellulose I. While the broader peak and lower CrI of untreated cellulose samples indicated lower crystalline structure of cellulose I. Pretreatment of cellulose with ionic liquid can provides a facile approach for the preparation of nanocellulose particles with high crystallinity.
24 citations
TL;DR: In this article, CNT samples were prepared by refluxing CNTs in nitric acid for 16 hours at 110 °C and then followed by thermal treatment, the Co catalyst was synthesized by the strong electrostatic adsorption (SEA) method on the treated CNT support.
Abstract: In this study, CNTs samples were prepared by refluxing CNTs in nitric acid for 16 h at 110 °C and then followed by thermal treatment. The Co catalyst was synthesized by the strong electrostatic adsorption (SEA) method on the treated CNTs support. The Co/CNTs samples were then calcined at temperatures of 300, 350, 400, 450 °C. Samples were characterized by TEM and N2 adsorption. The size of cobalt nanoparticles and the textural properties were influenced by the calcination temperature. The TEM results showed that cobalt nanoparticles were well dispersed on the treated CNTs support.
24 citations
TL;DR: In this paper, the authors present a short literature review on general aspects of promising biocompatible binary Ti-Mo alloys compared with CoCr and stainless steel alloys, as an alternative of the known metallic biomaterials.
Abstract: Metallic biomaterials are used in various applications of the most important medical fields (orthopedic, dental and cardiovascular). The main metallic biomaterials are stainless steels, Co-based alloys and Ti-based alloys. Recently, titanium alloys are getting much attention for biomaterials because these types of materials have very good mechanical properties, good corrosion resistance and an excellent biocompatibility. The paper contains important information about titanium alloys used for biomedical applications, which are considered the most widely. It is very important to understand the microstructural evolution and property-microstructure relationship in implant alloys. In the present paper, authors present a short literature review on general aspects of promising biocompatible binary Ti-Mo alloys compared with CoCr and stainless steel alloys, as an alternative of the known metallic biomaterials. This alloys show superior mechanical compatibility and very good biocompatibility. The aim of this review is to highlight the mechanical properties for several types of biomaterials, their application in medical field, especially the Ti-Mo group.
22 citations
TL;DR: In this paper, the SUS304L grade stainless steel has been used as a model material to understand and validate the response of the harmonic structure materials towards the applied external loads, and numerical simulation of multi-scale FEA (Finite Element Analysis) was carried out, and it was confirmed that microscopic deformation and the macroscopic tensile strength can be characterized by the present approach.
Abstract: The harmonic structure materials consist of coarse-grained areas enclosed in a three-dimensional continuously connected network of ultrafine-grained area. The concept of harmonic structure design has been successfully applied to a variety of pure metals and alloys by mechanical milling (MM) and subsequent powder metallurgy (PM) process. In harmonic structure material, core region with coarse grains maintains a high ductility while the shell region with ultrafine grains contributes for a higher strength. Therefore, the material with harmonic structure design can achieve both strength and ductility simultaneously. In this research, the SUS304L grade stainless steel has been used as a model material to understand and validate the response of the harmonic structure materials towards the applied external loads. The numerical simulation of multi-scale FEA (Finite Element Analysis) was carried out, and it was confirmed that microscopic deformation and the macroscopic tensile strength can be characterized by the present approach.
21 citations
TL;DR: In this article, the authors proposed the possibility of using the diesel generator with renewable energy sources (RES) and compared the cost of energy of isolated pv-wind-diesel-battery-converter hybrid system with a stand-alone diesel generator.
Abstract: This paper proposes the possibility of using the diesel generator with renewable energy sources (RES) and compares the cost of energy of isolated pv-wind-diesel-battery-converter hybrid system with a stand-alone diesel generator for a rural region in Egypt. The isolated system is also evaluated to find out the quantity of air pollution. The system has to supply a load with an average value of 48 kW and a peak value of 71 kW. HOMER software is used to carry out the cost of energy (COE), net present cost (NPC) and environmental emissions (Kg/yr) calculations of optimization model. The simulation results show that the proposed hybrid system is very economical and environment friendly. The COE for the isolated hybrid power system is found to be 0.139 $/kWh which is more than half of the stand alone diesel generator system.
TL;DR: In this article, the authors investigated the mechanical properties and fire resistivity of medium density fiberboards (MDF) made from renewable biomass namely empty fruit bunch fibre (EFB) and palm-based pre-PU as the binder.
Abstract: The aim of this study was to investigate the mechanical properties and fire resistivity of medium density fibreboards (MDF) made from renewable biomass namely empty fruit bunch fibre (EFB) and palm-based pre-PU as the binder. Aluminium hydroxide (ATH) was added in the mixture of EFB at size of 300 to 500 μm. The ratio of EFB to PU matrix was 35:65 with ATH at varying amount of 5, 10, and 15 wt% of the overall mass of the resin. The results showed that MDF-EFB has higher mechanical properties than MDF-EFB/ATH. However, the fire test indicated lower burning rate (from 0.15 mm/s to 0.27 mm/s) as the percentage loading of ATH increased.
TL;DR: A review of high temperature ceramics research for aerospace applications is presented in this paper, where the development of thermal protection systems is also reviewed within the context of thermal barrier coatings (TBCs) and thermal protection system for space vehicles.
Abstract: This paper presents a review of high temperature ceramics research for aerospace applications. Following a brief historical perspective, the paper reviews the effort to toughen ceramics for high temperature structural applications. These include: efforts to toughen zirconia-based ceramics, aluminum oxide, silicon carbide, silicon nitride, molybdenum disilicide and zirconium diborides and carbon-based composites. The development of thermal protection systems is also reviewed within the context of thermal barrier coatings (TBCs) and thermal protection systems for space vehicles. The paper concludes with a final section in which the implications of the results are then discussed for the thermostructural applications of ceramics in aerospace structures.
TL;DR: In this paper, the current status of research paper reviews several magnesium alloy protection methods at home and abroad, and also highlighted with our latest laser shock (LSP) study of AZ91 magnesium alloy at high strain rates of corrosion resistance results.
Abstract: Magnesium alloy as a green material in the 21st century, because of its excellent physical and mechanical properties of metallic materials as an ideal in the automotive industry, electronic industry and aviation, aerospace and other industries[1]. However, poor corrosion resistance of magnesium alloys become an important issue hinder application of magnesium alloys[2]. So magnesium alloy corrosion problems and the current status of research paper reviews several magnesium alloy protection methods at home and abroad, and also highlighted with our latest laser shock (LSP) study of AZ91 magnesium alloy at high strain rates of corrosion resistance results.
TL;DR: In this paper, the authors present experimental results on one-part geopolymers and global warming potential assessment and cost analysis, and show that only the use of aluminium powder allows the production mixtures with a high compressive strength however its high cost means they are commercially useless when facing the competition of commercial cellular concrete.
Abstract: Buildings are responsible for more than 40% of the energy consumption and greenhouse gas emissions. Thus, increasing building energy efficiency is one the most cost-effective ways to reduce emissions. The use of thermal insulation materials could constitute the most effective way of reducing heat losses in buildings by minimising heat energy needs. These materials have a thermal conductivity factor lower than 0.065 (W/m.K) while other insulation materials such as aerated concrete can go up to 0.11. Current insulation materials are associated with negative impacts in terms of toxicity. Polystyrene, for example contains anti-oxidant additives and ignition retardants. In addition, its production involves the generation of benzene and chlorofluorocarbons. Polyurethane is obtained from isocyanates, which are widely known for their tragic association with the Bhopal disaster. Besides current insulation materials releases toxic fumes when subjected to fire. This paper presents experimental results on one-part geopolymers. It also includes global warming potential assessment and cost analysis. The results show that only the use of aluminium powder allows the production mixtures with a high compressive strength however its high cost means they are commercially useless when facing the competition of commercial cellular concrete. The results also show that one-part geopolymer mixtures based on 26% Ordinary Portland Cement (OPC)+58.3% Fly Ash (FA)+8% Calcined Stuff (CS) +7.7% Calcium Hydroxide (CH) and 3.5% hydrogen peroxide constitute a promising cost efficient (67 euro/m3), thermal insulation solution for floor heating systems with low global warming potential of 443 KgCO2eq/m3.
TL;DR: In this article, a review paper on microencapsulation of essential oils (EOs) and their promising benefit in textile application has been presented, where techniques and material use to produce EOs microcapsule, also process condition, aiding agent and fabric impregnating procedure are also reviewed for further studies.
Abstract: Essential oils (EOs) widely known to possess various beneficial properties which are vital in numerous fields such as fragrance, flavour and medical. However, its high volatilities cause it ineffective in handling and utilizing for commercial application such as in textile. Although microencapsulation technology can trap oily components stably to fibers, a lots of affecting factor needs to be considered in order to have high performance microcapsules which can serve specific application. This review paper emphasize on microencapsulation of EOs and their promising benefit in textile application. Techniques and material use to produce EOs microcapsule, also process condition, aiding agent and fabric impregnating procedure are also reviewed for further studies.
TL;DR: In this paper, the density functional theory (DFT) method at IEF-PCM(UFF)/B3LYP/6-31+G(d,p) levels under ethanol and water environments was used to analyze dye electronic properties of anthocyanin aglycones to be used as photosensitizers for TiO2 solar cells.
Abstract: The aim of this study is to analyze dye electronic properties of anthocyanin aglycones to be used as photosensitizers for TiO2 solar cells. The dye properties will be examined by the density functional theory (DFT) method at IEF-PCM(UFF)/B3LYP/6-31+G(d,p) levels under ethanol and water environments. The results show that the position of LUMOs of all dyes lying over TiO2 ECB will facilitate good electron transfer while their HOMOs, which are lower than the electrolyte redox potential energy, can facilitate good oxidized-dye regeneration. Flavilium cation dye is the best anthocyanidin aglycone due to the best electron injection spontaneity of -0.807 eV as well as the highest open circuit voltage of 1.669 V. On the other hand, quinonoidal base dye gives the best light harvesting efficiency of 69.24% due to the best oscillating strength character. Moreover, the solvent effect is the important aspect regarding the dye oxidation potential stabilization as well as the electron injection driving force.
TL;DR: In this article, the effect of electrolyte concentration on anodized titanium was investigated by using glancing angle X-ray diffraction (GAXRD), field emission scanning electron microscope (FESEM), focused ion beam (FIB) milling and digital camera.
Abstract: Anodic oxidation is a surface modification method which combines electric field driven metal and oxygen ion diffusion for formation of oxide layer on the anode surface. Anodised titanium has been widely use in biomedical applications especially in dental implant. This study aimed to investigate the effect of electrolyte concentration on titanium. Specifically, the titanium foil was anodised in mixture of β-glycerophosphate disodium salt pentahydrate (β-GP) and calcium acetate monohydrate (CA) with different concentration (0.02 M + 0.2 M and 0.04 M + 0.4 M), anodising time (10 min), applied voltage (150, 200, 250, 300 and 350 V) and current density (10 mA.cm-2) at room temperature. Surface oxide properties of anodised titanium were characterised by using glancing angle X-ray diffraction (GAXRD), field emission scanning electron microscope (FESEM), focused ion beam (FIB) milling and digital camera. With increasing electrolyte concentration, the oxide layer became more porous. The GAXRD results also showed that rutile formed at high applied voltage (≥300 V) when the higher concentration of electrolyte was used.
TL;DR: In this paper, an evaluation of the scheduled waste management in Malaysia is made: in terms of legislation framework, type of wastes and waste volume production, and type of waste was evaluated.
Abstract: Industry has become an essential part of modern society, and waste production is an inevitable outcome of the developmental activities. A material becomes waste when it is discarded with impunity and may pose a potential hazard to the human health or the environment (soil, air, waste) when improperly treated, stored, transported or disposed off or managed. In other words, scheduled waste contributes a major share towards environmental degradation. Scheduled and hazardous waste is the most difficult waste to be managed due to the dangerous elements not only for the environment but also for public health. In Malaysia, in the last two decades, the waste management has been a major concern. Malaysia has developed a comprehensive set of legal provisions related to the management of toxic and hazardous wastes. In this work, an evaluation of the scheduled waste management in Malaysia is made: in term of legislation framework, type of wastes and waste volume production.
TL;DR: In this paper, small amplitude oscillatory shear (SAOS) rheometry was used to examine the storage and loss moduli of PDMS elastomer, Sylgard 184 (Dow Corning, USA), and heatcured with four curing temperatures from 25° to 150°C and four curing durations from 48 h to 25 min.
Abstract: Viscoelastic samples made from a PDMS elastomer, Sylgard 184 (Dow Corning, USA), were prepared using 9.1% and 3% curing agent (cross-linker) and heat-cured with four curing temperatures from 25° to 150°C and four curing durations from 48 h to 25 min. Small amplitude oscillatory shear (SAOS) rheometry was done to examine their mechanical properties, represented by the storage (G’) and loss (G”) moduli. Generally, G’ and G” are dependent on the frequency, curing agent percentage and curing temperature. The samples were then reheated and SAOS tested again to check the stability of G’ and G”. It was apparent that the stability of G’ and G” are both strongly dependent on the curing temperature. Samples with the curing temperature of 25°C yielded almost up to 4 times change of G” value for 9.1% curing agent and more than 2 times change of G’ value for 3% curing agent. Hence, the usage of 25°C curing temperature at the manufacturer recommended curing time is not suitable for applications where the linear viscoelastic stability is important. In general, the stability also improves as the frequency increases for all samples.
TL;DR: In this article, the effect of cooling rates on hardness and microstructure of medium carbon steel was investigated. But the results showed that the hardness values increased with increase of temperature, except at 1000 °C.
Abstract: The SAE/ AISI 1045, a type of medium carbon steel, is used most commonly in various structural and element of machines. Sometime, it failed during the in-service, which assumed to be caused by cracking in material as the effect of casting, manufacturing, or heat treatment processes. The current research was developed to find out the effect of hardening and of tempering processes toward hardness, microstructure and cracking. The objectives of the current research are to obtain the effect of cooling rates toward the hardness and cracking and to define a proper cooling media to get a martensite microstructure without cracking of heat resistant products. Results showed that the chemical composition from the spectrometry test confirmed that the specimens were classified as AISI 1045 or JIS S45C. The hardness values properties increased with increase of temperature, except at 1000 °C. The specimens having the hardness property more than that of ASME II standard were not useable due to its brittle.
TL;DR: In this article, permanent magnets ferrites have been prepared by recycling the steel waste product, which is a form of flakes is grinding for several hours to form a fine powder, the iron oxides powders are separated from magnetic and non-magnetic particle using magnetic particle separation.
Abstract: In this project, the permanent magnets ferrites have been prepared by recycle the steel waste product. Steel waste is an impure material that contains the iron oxides and impurities. The steel waste product is a form of flakes is grinding for several hours to form a fine powder. The iron oxides powders are separated from magnetic and non-magnetic particle using magnetic particle separation. The magnetic particles was again been purified by using the Curie temperature separation. The magnetic powder carried out from the purification was heated at 500 °C for 6 hours at 6 °C/ mins to form hematite, Fe2O3. The constitute amount of BaCO3 and Fe2O3 derived by steel waste product are mixed by using mechanical alloying to prepare the barium hexaferrites (BaFe12O19). The samples were sintered at different temperature 600/800/1000/1200 °C for 6 hours at 6 °C/ mins. The composition of FeO, Fe3O4 and Fe2O3 of the steel waste product was carried out using X-ray Fluorescence (XRF) and Energy Dispersive Spectroscopy (EDAX). The crystallography of sample is observed by using X-ray Diffraction (XRD). Microstructure of samples was carried out by using Field Emission Scanning Electron Microscope (FESEM) and Atomic Force Microscopy (AFM). The saturation magnetization, Curie temperature and density are also observed. The results show the purification process yields high purity of hematite, Fe2O3. The common characteristics of the steel waste product are its low cost, availability and thus the potential for large production volumes, need for recycling, and tendency to further oxidation in the production of ferrites.
TL;DR: In this article, the authors investigated the possibility of synthesizing high yield of cassava starch nanocrystals at different concentration of sulphuric acid (H2SO4) and investigated the physical and chemical properties of synthesize CSN.
Abstract: Cassava starch nanocrystals (CSN) has not been reported in open literature, although other starches such as rice, corn, potato and bean were widely used as the main material. Thus, the objective of this research was to investigate the possibility of synthesizing high yield of CSN at different concentration of sulphuric acid (H2SO4). The physical and chemical properties of synthesize CSN was also investigated. Synthesized CSN was prepared by hydrolysing native cassava starch (NCS) with several concentration of H2SO4 (2.8 M, 3.0 M, 3.2 M and 3.4 M). The acid hydrolysis process took five days with continuous stirring speed of 300 to 400 rpm, with constant temperature of 37 °C. The hydrolysed solution of CSN underwent centrifuging process with distilled water until neutral to make sure that no acid residues remain in the CSN solution. The CSN precipitate was dried in an oven over night at 60 °C. The highest yield (1.1 %) produced was from 3.4 M CSN. Morphology test by Transmission Electron Microscopy indicated that the samples have been destructed and degraded to be nanocrystals with a size range of 5 - 20 nm. X-ray Diffraction (XRD) and 13C Nuclear Magnetic Resonance (NMR) were used to indicate the type of crystallinity for both NCS and CSN.
TL;DR: In this article, a simple electrostatic-heating coating (EHC) method was used to immobilize titanium dioxide particles on polypropylene copolymer surfaces (TiO2/PC) and applied to degrade methylene blue (MB) solution as a wastewater model under direct sunlight exposure.
Abstract: Titanium dioxide particles immobilized on polypropylene copolymer surfaces (TiO2/PC) have been successfully performed using a simple electrostatic-heating coating (EHC) method. The coating process was initiated by generating electroctatic charges on the polymer surfaces, followed by adhering TiO2 particles electrostatically onto the surface and completing with pressing at 110 o C for 4 minutes. The coated sheets have been applied to degrade methylene blue (MB) solution as a wastewater model under a direct sunlight exposure. Ten layers of TiO2 coated sheets produced the optimum decomposition rate with photodegradation effectiveness up to 99.30% for 4 days exposure. These materials are also repeatedly used, indicated by nearly unchange in the photodegradation effectiveness. After four times repetition, the coated sheets still function well by decomposition up to 99 % of MB compound. The material has potential for large scale wastewater treatment in the tropical regions.
TL;DR: In this article, the authors provide a detailed review of solar cell and battery development applicable to small UAVs, including the technologies of miniature electric motors, batteries, fuel cells, and solar cells.
Abstract: Electric unmanned aerial vehicle (UAV) systems powered solely by battery cannot achieve long endurance. Despite recent improvements in battery technology, UAVs barely last for 4 hours, thereby decreasing the attractiveness of battery-powered UAVs. Progress has been made in developing hybrid-powered solar and battery systems for UAVs. However, the small number of solar UAVs developed indicates the research gap, particularly in the aspect of power system and integration. Accordingly, this paper provides a detailed review of solar cell and battery development applicable to small UAVs. This review includes the technologies of miniature electric motors, batteries, fuel cells, and solar cells. A comprehensive battery and solar cell technology trend is then discussed. This wok elucidates the effect of solar and battery technology progress on solar UAV development. The combination of electric motor, battery, and solar cells offers an excellent solution to the requirements of various long-endurance applications.
TL;DR: In this article, the special features of nanoparticles formation by laser ablation of volume metallic zinc targets in various solvents using sulfur precursors were studied. But the authors focused on the optical properties of the nanoparticles and only CdS particles were formed in the medium.
Abstract: The special features of nanoparticles formation by laser ablation of volume metallic zinc targets in various solvents using sulfur precursors are studied. Semiconductor cadmium sulphide nanoparticles with average sizes 10–15 nm are synthesized by zinc ablation in the presence of hydrogen sulfide and thioacetamide, and their composition, structure, and optical properties are investigated. It is established that with the use of H2S, only CdS particles are formed in the medium.
TL;DR: In this article, an electrochemical exfoliation method was adopted in the production of graphene oxide (GO), and the electrolyte used was sodium dodecyl sulphate (SDS) aqueous solution at various concentrations from 0.001 to 1.0 M. The effect of SDS concentrations on the morphology of GO samples were characterized using field emission scanning electron microscopy (FESEM), energy dispersive X-ray, micro-Raman and UV-Vis spectroscopy.
Abstract: In this study, electrochemical exfoliation method was adopted in the production of graphene oxide (GO). The electrolyte used was sodium dodecyl sulphate (SDS) aqueous solution at various concentrations from 0.001 to 1.0 M. The effect of SDS concentrations on the morphology of GO samples were characterized using field emission scanning electron microscopy (FESEM), energy dispersive X-ray, micro-Raman and UV-Vis spectroscopy. As evident by the FESEM analysis, the concentration of SDS does give effect to the GO obtained in this study. The lowest GO production is given by the lowest concentration of SDS used which is 0.001 M. However, in term of ID/IG ratio, the sample prepared at 0.001 M has the lowest value (0.33) as compared to the sample prepared with highest SDS concentration of 1.0 M (ID/IG ~1.12). Meanwhile, the presence of absorbance peaks in the range of 224-237 nm from UV-Vis spectra analysis were seen for the whole samples and this indicate the formation of GO.
TL;DR: In this article, the surface morphology and crystallinity of titanium foil was modified by anodising in mixture of β-glycerophosphate disodium salt pentahydrate (β-GP) and calcium acetate monohydrate (CA).
Abstract: Anodic oxidation is an electrochemical method for the production of ceramic films on a metallic substrate. It had been widely used to deposit the ceramic coatings on the metals surface. In this study, the surface morphology and crystallinity of titanium foil was modified by anodising in mixture of β-glycerophosphate disodium salt pentahydrate (β-GP) and calcium acetate monohydrate (CA). The experiments were carried out at high voltage (350 V), different anodising time (1, 3, 5 and 10 min) and current density (10 and 20 mA.cm-2) at room temperature. Anodised titanium was characterised by using glancing angle X-ray diffraction (GAXRD), field emission scanning electron microscope (FESEM) and focused ion beam (FIB) milling. The result of the experiment show that colour, porosity, crystallinity and thickness of the titanium films depended strongly on the current density. More porous surface and large amount of anatase was produced at higher current density. FIB results indicated that the thickness of oxide layer increased as increasing of current density.
TL;DR: In this article, a green approach for the reduction of graphene oxide by using reducing sugars to synthesis graphene was reported, which avoided the use of toxic and environmentally harmful reductants.
Abstract: A new carbon material called graphene has been attracting an increasing research interest owing to its unique electrical and mechanical properties that is useful for the various device applications. The synthesis of graphene from graphene oxide usually involves harmful chemical reducing agents that are toxic and undesirable to human and the environment. By avoiding the use of toxic and environmentally harmful reductants, we report a green approach for the reduction of graphene oxide by using reducing sugars to synthesis graphene. Graphite oxide was synthesized from graphite powder using modified Hummers method. Graphite oxide then further exfoliated to graphene oxide by using ultrasonic irradiation. Graphene then was obtained by the mild reduction of graphene oxide with reducing sugars (glucose, lactose and maltose). The structural study of the as-prepared graphene is characterized by Raman spectroscopy and fourier infra red spectroscopy. Raman and FTIR spectra indicates the partial removal of oxygen functional groups from the surface of GO. Characterizations indicate that graphene oxide is successfully reduced to graphene by sugar.
TL;DR: In this paper, a review of microencapsulation methods of volatiles essential oils and the basic release characteristic of the active ingredients from the capsules is presented. But, their inadequate volatile characteristics made it less efficient, and the choice of micro encapsulation method is very much affected by the material to be encapsulated, wall material and its application.
Abstract: Essential oil contained volatile compounds and they are benefit in many fields such as pharmaceutical, flavor, perfume, food, agriculture, and detergent. However, its inadequate volatile characteristics made it less efficient. Many microencapsulation methods were conducted for varies essential oils. The choice of microencapsulation method very much affected by the material to be encapsulated, wall material and its application. This review paper highlighted on microencapsulation methods of volatiles essential oils and the basic release characteristic of the active ingredients from the capsules.