Search results for: zinc oxide nanocomposites

Authors: Khalid Ahmed Eldwaib

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In this study, Al-Mg alloy 5052 was used as the testing material. Corrosion fatigue life was studied for the alloy in 3.5% NaCl (pH=1, 3, 5, 7, 9, and 11), and 3.5% NaCl (pH=1) with inhibitors. The compound inhibitors were composed mainly of phosphate (PO4³-), adding a certain proportion of other nontoxic inhibitors so as to select alternatives to environmentally hazardous chromate (Cr2O7²-). The inhibitors were sodium dichromate Na2Cr2O7, sodium phosphate Na3PO4, sodium molybdate Na2MoO4, and sodium citrate Na3C6H5O7. The total amount of inhibiting pigments was at different concentrations (250,500,750, and 1000 ppm) in the solutions. Corrosion fatigue behavior was studied by using plane-bending corrosion fatigue machine with stress ratio R=0.5 and under the constant frequency of 13.3 Hz. Results show that in 3.5% NaCl the highest fatigue life (number of cycles to failure Nf) is obtained at pH=5 where the oxide film on aluminum has very low solubility, and the lowest number of cycles is obtained at pH=1, where the media is too aggressive (extremely acidic). When the concentration of inhibitor increases the cycles to failure increase. The surface morphology and fracture section of the specimens had been characterized through scanning electron microscope (SEM).

Keywords: Al-Mg alloy 5052, corrosion, fatigue, inhibitors

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Authors: Vincent King Soon Wong, Hong Seng Ng, Florinna Sim

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Negative Bias Temperature Instability (NBTI) is one of the critical degradation mechanisms in semiconductor device reliability that causes shift in the threshold voltage (Vth). However, thorough understanding of this reliability failure mechanism is still unachievable due to a recovery characteristic known as NBTI recovery. This paper will demonstrate the severity of NBTI recovery as well as one of the effective methods used to mitigate, which is the minimization of measurement system delays. Comparison was done in between two measurement systems that have significant differences in measurement delays to show how NBTI recovery causes result deviations and how fast measurement systems can mitigate NBTI recovery. Another method to minimize NBTI recovery without the influence of measurement system known as Fast Wafer Level Reliability (FWLR) NBTI was also done to be used as reference.

Keywords: fast vs slow BTI, fast wafer level reliability (FWLR), negative bias temperature instability (NBTI), NBTI measurement system, metal-oxide-semiconductor field-effect transistor (MOSFET), NBTI recovery, reliability

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Authors: Napat Hataivichian

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The effect of transition metal doping on Pt/Al2O3 catalyst used in propane dehydrogenation reaction at 500˚C was studied. The preparation methods investigated were sequential impregnation (Pt followed by the 2nd metal or the 2nd metal followed by Pt) and co-impregnation. The metal contents of these catalysts were fixed as the weight ratio of Pt per the 2nd metal of around 0.075. These catalysts were characterized by N2-physisorption, TPR, CO-chemisorption and NH3-TPD. It was found that the impregnated 2nd metal had an effect upon reducibility of Pt due to its interaction with transition metal-containing structure. This was in agreement with the CO-chemisorption result that the presence of Pt metal, which is a result from Pt species reduction, was decreased. The total acidity of bimetallic catalysts is decreased but the strong acidity is slightly increased. It was found that the stability of bimetallic catalysts prepared by co-impregnation and sequential impregnation where the 2nd metal was impregnated before Pt were better than that of monometallic catalyst (undoped Pt one) due to the forming of Pt sites located on the transition metal-oxide modified surface. Among all preparation methods, the sequential impregnation method- having Pt impregnated before the 2nd metal gave the worst stability because this catalyst lacked the modified Pt sites and some fraction of Pt sites was covered by the 2nd metal.

Keywords: alumina, dehydrogenation, platinum, transition metal

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Authors: Niloofar Alipoormazandarani

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The rift environmental, efficiency and being environmental-friendly of these innovative food packaging in edible films made them as an alternative to synthetic packages. This issue has been widely studied in this experiment. Some of the greatest advances in food packaging industry is associated with nanotechnology. Recently, a polysaccharide extracted from the cell wall of soybean cotyledons: A soluble soybean polysaccharide (SSPS), a pectin-like structure. In this study, the addition (0%, 1%, 3%, and 5%) of nano silica dioxide (SiO2) film is examined SSPS in different features. The research aims to investigate the effect of nano-SiO2 on the physicochemical and electromagnetic properties of the SSPS films were sonicated and then heated to the melting point, besides the addition of plasticizer. After that, it has been cooled into the room temperature and were dried with Casting method. In final examinations,improvement in Moisture Content and Water Absorption was observed with a significant decrease.Also, in Color measurements there were some obvious differences. These reports indicate that the incorporation of nano-SiO2 and SSPS has the power to be extensively used in pharmaceutical and food packaging industry as well.

Keywords: SSPS, NanoSiO2, food packaging, renewable films

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Authors: Bayan Alqassem, Israa A. Othman, Mohammed Abu Haija, Fawzi Banat

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The treatment of wastewater from highly toxic pollutants is one of the most challenging issues for humanity. In this study, the advanced oxidation process (AOP) was employed to study the catalytic degradation of phenol using different ferrite catalysts which are CoFe₂O₄, CrFe₂O₄, CuFe₂O₄, MgFe₂O₄, MnFe₂O₄, NiFe₂O₄ and ZnFe₂O₄. The ferrite catalysts were prepared via sol-gel and co-precipitation methods. Different ferrite composites were also prepared either by varying the metal ratios or incorporating chemically reduced graphene oxide in the ferrite cluster. The effect of phosphoric acid treatment on the copper ferrite activity. All of the prepared catalysts were characterized using infrared spectroscopy (IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The ferrites catalytic activities were tested towards phenol degradation using high performance liquid chromatography (HPLC). The experimental results showed that ferrites prepared through sol-gel route were more active than those of the co-precipitation method towards phenol degradation. In both cases, CuFe₂O₄ exhibited the highest degradation of phenol compared to the other ferrites. The photocatalytic properties of the ferrites were also investigated.

Keywords: ferrite catalyst, ferrite composites, phenol degradation, photocatalysis

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Authors: Edwin Oviedo, Carlos Linares, Philippe Ayrault, Sylvette Brunet

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Nowadays, light conventional crude oils are going down. Therefore, the exploitation of heavy crude oils has been increasing. Hence, a major quantity of refractory sulfur compounds such as dibenzothiophene (DBT) should be removed. Many efforts have been carried out to modify hydrotreatment typical supports in order to increase hydrodesulfurization (HDS) reactions. The present work shows the synthesis of tertiaries MgFeAl(0.16), MgFeAl(0.32), CoFeAl, ZnFeAl hydrotalcites, as supports of CoMo based catalysts, where 0.16 and 0.32 are the Fe3+/Al3+ molar ratio. Solids were characterized by different techniques (XRD, CO2-TPD, H2-TPR, FT-IR, BET, Chemical Analysis and HRTEM) and tested in the DBT HDS reaction. The reactions conditions were: Temp=325°C, P=40 Bar, H2/feed=475. Results show that the catalysts CoMo/MgFeAl(0.16) and CoMo/MgFeAl(0.32), which were the most basics, reduced the sulfur content from 500ppm to less than 1 ppm, increasing the cyclohexylbenzene content, i.e. presented a higher selective toward the HYD pathway than reference catalyst CoMo/γ- Al2O3. This is suitable for improving the fuel quality due to the increase of the cetane number. These catalysts were also more active to the HDS reaction increasing the direct desulfurization (DDS) way and presented a good stability. It is advantageous when the gas oil centane number should be improved. Cobalt, iron or zinc species inside support could avoid the Co and Mo dispersion or form spinel species which could be less active to hydrodesulfuration reactions, while hydrotalcites containing Mg increases the HDS activity probably due to improved Co/Mo ratio.

Keywords: catalyst, cetane number, dibenzothiophene, diesel, hydrodesulfurization, hydrotreatment, MoS2

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Authors: T. M. Aminu, A. Salisu, B. Abdu, H. U. Alhassan, T. H. Dharma

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Thin films of CuAlO2 were deposited on clean glass substrate using the chemical solution deposition (sol-gel) method of deposition with CuCl and AlCl3 taken as the starting materials. CuCl was dissolved in HCl while AlCl₃ in distilled water, pH value of the mixture was controlled by addition of NaOH. The samples were annealed at different temperatures in order to determine the effect of annealing temperatures on the morphological and optical properties of the deposited CuAlO₂ thin film. The surface morphology reveals an improved crystalline as annealing temperature increases. The results of the UV-vis and FT-IR spectrophotometry indicate that the absorbance for all the samples decreases sharply from a common value of about 89% at about 329 nm to a range of values of 56.2%-35.2% and the absorption / extinction coefficients of the films decrease with increase in annealing temperature from 1.58 x 10⁻⁶ to1.08 x 10⁻⁶ at about 1.14eV in the infrared region to about 1.93 x 10⁻⁶ to 1.29 x 10⁻⁶ at about 3.62eV in the visible region, the transmittance, reflectance and band gaps vary directly with annealing temperature, the deposited films were found to be suitable in optoelectronic applications.

Keywords: copper aluminium-oxide (CuAlO2), absorbance, transmittance, reflectance, band gaps

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Authors: Lista Andriyati, Nurpudji A Taslim

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The human immunodeficiency virus (HIV) patients have potential nutritional and metabolic problems. HIV is a virus that attacks cells T helper and impairs the function of immune cells. Infected individuals gradually become immunodeficient, results in increased susceptibility to a wide range of infections such as tuberculosis (TB). Malnutrition has destructive effects on the immune system and host defense mechanisms. Effective and proper nutritional therapies are important to improve medical outcomes and quality of life, which is associated with functional improvement. A case of 38-years old man admitted to hospital with loss of consciousness and was diagnosed HIV infection and relapse lung TB with severe malnutrition, fever, oral candidiasis, anemia (6.3 g/dL), severe hypoalbuminemia (1.9 g/dL), severe hypokalemia (2.2 mmol/L), immune depletion (1085 /µL) and elevated liver enzyme (ALT 1198/AST 375 U/L). Nutritional intervention by giving 2300 kcal of energy, protein 2 g/IBW/day, carbohydrate 350 g, fat 104 g through enteral and parenteral nutrition. Supplementations administered are zinc, vitamin A, vitamin B1, vitamin B6, vitamin B12, vitamin C, vitamin D, and snakehead fish extract high content of protein albumin (Pujimin®). After 46 days, there are clinical and metabolic improvement in Hb (6.3 to 11.2 g/dL), potassium (2.2 to 3.4 mmol/L), albumin (1.9 to 2.3 g/dL), ALT 1198 to 47/AST 375 to 68 U/L) and improved awareness. In conclusion, nutritional therapy in HIV infection with adequate macronutrients and micronutrients fulfillment and immunonutrition is very important to avoid cachexia and to improve nutritional status and immune disfunction.

Keywords: HIV, hypoalbuminemia, malnutrition, tuberculosis

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Authors: Neeraj Neeraj, Soumen Basu, Banibrata Maity

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Glutathione (GSH) is one of the most important biomolecules having small molecular weight, which helps in various cellular functions like regulation of gene, xenobiotic metabolism, preservation of intracellular redox activities, signal transduction, etc. Therefore, the detection of GSH requires huge attention by using extremely selective and sensitive techniques. Herein, a rapid fluorometric nanosensor is designed by combining carbon dots (Cdots) and MnO₂ nanoparticles of different sizes for the detection of GSH. The bottom-up approach, i.e., microwave method, was used for the preparation of the water soluble and greatly fluorescent Cdots by using ascorbic acid as a precursor. MnO₂ nanospheres of different sizes (large, medium, and small) were prepared by varying the ratio of concentration of methionine and KMnO₄ at room temperature, which was confirmed by HRTEM analysis. The successive addition of MnO₂ nanospheres in Cdots results fluorescence quenching. From the fluorescence intensity data, Stern-Volmer quenching constant values (KS-V) were evaluated. From the fluorescence intensity and lifetime analysis, it was found that the degree of fluorescence quenching of Cdots followed the order: large > medium > small. Moreover, fluorescence recovery studies were also performed in the presence of GSH. Fluorescence restoration studies also show the order of turn on follows the same order, i.e., large > medium > small, which was also confirmed by quantum yield and lifetime studies. The limits of detection (LOD) of GSH in presence of Cdots@different sized MnO₂ nanospheres were also evaluated. It was observed thatLOD values were in μM region and lowest in case of large MnO₂ nanospheres. The separation distance (d) between Cdots and the surface of different MnO₂ nanospheres was determined. The d values increase with increase in the size of the MnO₂ nanospheres. In summary, the synthesized Cdots@MnO₂ nanocomposites acted as a rapid, simple, economical as well as environmental-friendly nanosensor for the detection of GSH.

Keywords: carbon dots, fluorescence, glutathione, MnO₂ nanospheres, turn off-on

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Authors: Anushree, Chhaya Sharma, Satish Kumar

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Catalytic wet air oxidation (CWAO) is normally carried out at elevated temperature and pressure. This work investigates the potential of NiO-CeO₂ nano-catalyst in CWAO of paper industry wastewater under milder operating conditions of 90 °C and 1 atm. The NiO-CeO₂ nano-catalysts were synthesized by a simple co-precipitation method and characterized by X-ray diffraction (XRD), before and after use, in order to study any crystallographic change during experiment. The extent of metal-leaching from the catalyst was determined using the inductively coupled plasma optical emission spectrometry (ICP-OES). The catalytic activity of nano-catalysts was studied in terms of total organic carbon (TOC), adsorbable organic halides (AOX) and chlorophenolics (CHPs) removal. Interestingly, mixed oxide catalysts exhibited higher activity than the corresponding single-metal oxides. The maximum removal efficiency was achieved with Ce₄₀Ni₆₀ catalyst. The results indicate that the CWAO process is efficient in removing the priority organic pollutants from wastewater, as it exhibited up to 59% TOC, 55% AOX, and 54 % CHPs removal.

Keywords: catalysis, nano-materials, NiO-CeO2, paper mill, wastewater, wet air oxidation

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Authors: Nikhil Jain, Bin Yu

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We explore the potential of using ultra-thin hexagonal boron nitride (h-BN) as both supporting substrate and gate dielectric for graphene-channel field effect transistors (GFETs). Different from commonly used oxide-based dielectric materials which are typically amorphous, very rough in surface, and rich with surface traps, h-BN is layered insulator free of dangling bonds and surface states, featuring atomically smooth surface. In a graphene-channel-last device structure with local buried metal gate electrode (TiN), thin h-BN multilayer is employed as both supporting “substrate” and gate dielectric for graphene active channel. We observed superior carrier mobility and electrical conduction, significantly improved from that in GFETs with SiO2 as substrate/gate insulator. In addition, we report excellent dielectric behavior of layered h-BN, including ultra-low leakage current and high critical electric field for breakdown.

Keywords: graphene, field-effect transistors, hexagonal boron nitride, dielectric strength, tunneling

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Authors: Marcin Maslowski, Marian Zaborski

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The aim of the study was to receive magnetorheological elastomer composites (MRE) with the best mechanical characteristics. MRE based on different magnetoactive fillers in ethylene-octene rubber are reported and studied. To improve mechanical properties of polymer mixtures, also carbon black (N550) was added during the composites preparation process. Micro and nan-sized magnetites (Fe3O4), as well as gamma iron oxide (gamma-Fe2O3) and carbonyl iron powder (CIP) are added together with carbon black (N550) were found to be an active fillers systems improving both static and dynamic mechanical properties of elastomers. They also changed magnetic properties of composites. Dynamic-mechanical analysis (DMA) indicates the presence of strongly developed secondary structure in vulcanizates. Reinforcing character of applied different fillers systems results in an increased stress at 100% elongation, tensile strength and cross-linking density of the vulcanizates. Studies investigated by vibration sample magnetometer (VSM) proved that all composites exhibit good magnetic properties.

Keywords: carbon black, mechanical properties, magnetorheological composites, magnetic fillers

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Authors: Bhupinder Kaur, P. P. Srivastav

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The fruit and vegetable industries are responsible for producing huge amount of waste, which is a problem to environmental safety and should be utilized efficiently. Mango (Mangifera indica L.) is an important commercially grown fruit and referred as the “King of fruits”. In 2015, India was the largest producer (18.506 MT) of mangoes and out of which 9.16 % lost during post-harvest handling. The mango kernel and peel represent approximately 17-22% and 7-22% of the overall mass of fruit respectively and discarded as waste. Hence, an attempt has been made with three mango cultivars (Langra, Dashehari, Fazli) to investigate the effect of cryogenic grinding on various characteristics of mango peel powder (MPP). The cryogenic grinding is an emerging technology which is used for retention of beneficial volatile and bioactive components. The feed rate was highest for Langra followed by Chausa. The samples have 2-4% fat along with significant amount of protein (4-6%) and crude fiber (9-13%). Mango peel is also a good source of minerals such as calcium, potassium, manganese, iron, copper, zinc, and magnesium. Interestingly, the significant amount of essential minerals like phosphorus and chlorine in all the varieties was found with the highest value in Langra (phosphorus 10.83% and chlorine 2.41%) which are not reported earlier. SEM analysis revealed the surface morphology and shape of the particles. Waste utilization is a promising measure from both an environmental and economic point of view. Chemical characterization of the samples indicated its potential to be used for the fortification of food products which in turn reduces hazards due to waste and improve functional quality of the foods.

Keywords: cryogenic grinding, morphological, mineral composition, SEM

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Authors: Elitsa Kolentsova, Dimitar Dimitrov, Krasimir Ivanov

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The catalytic oxidation of methanol to formaldehyde is an important industrial process in which the waste gas in addition to CO contains methanol and dimethyl ether (DME). Evaluation of the possibility of removing the harmful components from the exhaust gasses needs a more complex investigation. Our previous work indicates that supported Cu-Mn oxide catalysts are promising for effective deep oxidation of these compounds. This work relates to the catalyst, comprising copper-manganese spinel, coated on carrier γ-Al₂O₃. The effect of preparation conditions on the active component composition and activity behavior of the catalysts is discussed. Different organometallic compounds on the base of four natural amino acids (Glycine, Alanine, Valine, Leucine) as precursors were used for the preparation of catalysts with Cu/Mn molar ratio 1:5. X-Ray and TEM analysis were performed on the catalyst’s bulk, and surface composition and the specific surface area was determined by BET method. The results obtained show that the activity of the catalysts increase up to 40% although there are some specific features, depending on the nature of the amino acid and the oxidized compound.

Keywords: Cu-Mn/γ-Al₂O₃, CO and VOCs oxidation, heterogeneous catalysis, amino acids

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Authors: M. Al Nur, M. S. Kaiser

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Corrosion behaviour of hypereutectic Al-19Si automotive alloy in different pH=1, 3, 5, 7, 9, 11, and 13 environments was carried out using conventional gravimetric measurements and was complemented by resistivity, optical micrograph, scanning electron microscopy (SEM) and X-ray analyzer (EDX) investigations. Gravimetric analysis confirmed that the highest corrosion rate is shown at pH 13 followed by pH 1. Minimum corrosion occurs in the pH range of 3.0 to 11 due to establishment of passive layer on the surface. The highest corrosion rate at pH 13 is due to the presence of sodium hydroxide in the solution which dissolves the surface oxide film at a steady rate. At pH 1, it can be attributed that the presence of aggressive chloride ions serves to pick up the damage of the passive films at localized regions. With varying exposure periods by both, the environment complies with the normal corrosion rate profile that is an initial steep rise followed by a nearly constant value of corrosion rate. Resistivity increases in case of pH 1 solution for the higher pit formation and decreases at pH 13 due to formation of thin film. The SEM image of corroded samples immersed in pH 1 solution clearly shows pores on the surface and in pH 13 solution, and the corrosion layer seems more compact and homogenous and not porous.

Keywords: Al-Si alloy, corrosion, pH, resistivity, scanning electron microscopy (SEM)

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Authors: Justina I. R. Udotong, Ime R. Udotong, Offiong U. Eka

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The concentrations of heavy metals in sediments of Qua Iboe River Estuary (QIRE) were monitored at four different sampling locations in wet and dry seasons. A preliminary survey to determine the four sampling stations along the river continuum showed that the area spanned between < 0.1% salinity at the control station and 21.5‰ at the fourth station along the river continuum. A preliminary survey to determine the four sampling locations along the river estuary showed variations in salinity and other physicochemical parameters. The estuary was found to be polluted with heavy metals from point and nonpoint sources at varying degrees. Mean values of 7.80 mg/kg, 4.97 mg/kg and 2.80 mg/kg of nickel were obtained for sediment samples from Douglas creek, Qua Iboe and Atlantic sampling locations, respectively in the dry season. The wet season nickel concentrations were however lower. The entire study area was grossly contaminated by iron. At Douglas creek, the concentration of iron in sediment was 9274 ± 9.54 mg/kg while copper, nickel, lead and vanadium were <0.5 mg/kg each as compared to iron. Bioaccumulation was therefore suspected within the study area as values of 31.00 ± 0.79, 36.00 ± 0.10 and 55.00 ± 0.05 mg/kg of zinc were recorded in sediment at Douglas creek, Atlantic and the control sampling locations. The results from this study showed that the source of these heavy metals were from point sources like the corrosion of metal steel pipes from old bridges as well as oily sludge wastes from the Qua Iboe Terminal / tank farm located within the vicinity of the study area.

Keywords: heavy metal, Qua Iboe River estuary, seasonal variations, Sediment

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Authors: Gabi N. Nehme, Saeed Ghalambor

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The use of titanium fluoride and iron fluoride (TiF3/FeF3) catalysts in combination with polutetrafluoroethylene (PTFE) in plain zinc dialkyldithiophosphate (ZDDP) oil is important for the study of engine tribocomponents and is increasingly a strategy to improve the formation of tribofilm and to provide low friction and excellent wear protection in reduced phosphorus plain ZDDP oil. The influence of surface roughness and the concentration of TiF3/FeF3/PTFE were investigated using bearing steel samples dipped in lubricant solution @100°C for two different heating time durations. This paper addresses the effects of water drop contact angle using different surface finishes after treating them with different lubricant combination. The calculated water drop contact angles were analyzed using Design of Experiment software (DOE) and it was determined that a 0.05 μm Ra surface roughness would provide an excellent TiF3/FeF3/PTFE coating for antiwear resistance as reflected in the scanning electron microscopy (SEM) images and the tribological testing under extreme pressure conditions. Both friction and wear performance depend greatly on the PTFE/and catalysts in plain ZDDP oil with 0.05% phosphorous and on the surface finish of bearing steel. The friction and wear reducing effects, which was observed in the tribological tests, indicated a better micro lubrication effect of the 0.05 μm Ra surface roughness treated at 100°C for 24 hours when compared to the 0.1 μm Ra surface roughness with the same treatment.

Keywords: scanning electron microscopy, ZDDP, catalysts, PTFE, friction, wear

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Authors: Rafeza Begum, Mohammad Mokhlesur Rahman, Safikul Moula, Rafiqul Islam

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Potassium (K) is crucial for healthy soil and plant growth. However, K fertilization is either disregarded or poorly underutilized in Bangladesh agriculture, despite the great demand for crops. This could eventually result in a significant depletion of the soil's potassium reserves, irreversible alteration of the minerals that contain potassium, and detrimental effects on crop productivity. Soil K mining in Bangladesh is a worrying problem, and we need to evaluate it thoroughly and find remedies. A pot culture experiment was conducted in the greenhouse of Bangladesh Institute of Nuclear Agriculture (BINA) using eleven soil series of Bangladesh in order to see the depletion behaviour of potassium (K) by continuous cropping using rice (var. Iratom-24) as the test crop. The soil series were Ranishankhail, Kaonia. Sonatala, Silmondi, Gopalpur, Ishurdi, Sara, Kongsha, Nunni, Lauta and Amnura on which four successive rice plants (45 days duration) were raised with (100 ppm K) or without addition of potassium. Nitrogen, phosphorus, sulfur and zinc were applied as basal to all pots. Potassium application resulted in higher dry matter yield, increased K concentration and uptake in all the soils compared with no K treatment; which gradually decreased in the subsequent harvests. Furthermore, plant takes up K not only from exchangeable pool but also from non-exchangeable sites and a minimum replenishment of K from the soil reserve was observed. Continuous cropping has resulted in the depletion of available K of the soil. The result indicated that in order to sustain higher crop yield under intensive cultivation, the addition of potash fertilizer is necessary.

Keywords: potassium, exchangeable pool, depletion behavior., Soil series

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Authors: N. Rajmohan, M. R. Swaminathan

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The performance of a diesel engine depends mainly on mixing of the fuel and air in the combustion chamber. The diesel engine suffers from significant generation of nitric oxide and particulate matter emission due to incomplete combustion. As the fuel is injected directly into the combustion chamber in conventional diesel engines, spatial distributions of air-fuel ratio vary widely from rich to lean in combustion chamber. The NOx is formed in stoichiometric zone and smoke is generated during diffusion combustion period where the combustion rate becomes slower. One of the effective methods to reduce oxides of nitrogen and particulate matter emissions simultaneously is to reduce the intake charge temperature in diesel engines. Therefore, in the present study, the effect of water injection into intake air on performance and emission characteristic of single cylinder CI engine are carried out at different load and constant speed, with variable water to diesel ratio by mass. The water is injected into intake air by an elementary carburetor.

Keywords: engine emission control, oxides of nitrogen, diesel engine, ignition engine

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Authors: Alieh Farshbaf, Tayyeb Bahrami

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Introduction: Cc-chemokine receptor-5 (CCR5) is known as a main co-receptor in human immunodeficiency virus type-1 (HIV-1) infection. Many studies showed 32bp deletion (Δ32) in CCR5 gene, provide natural resistance to HIV-1 infection in homozygous individuals. Inducing the resistance mechanism by CCR5 in HIV-1 infected patients eliminated many problems of highly-active-anti retroviral therapy (HAART) drugs like as low safety, side-effects and virus rebounding from latent reservoirs. New treatments solved some restrictions that are based on gene modification and cell therapy. Literature review: The stories of the “Berlin and Boston patients” showed autologous hematopoietic stem cells transplantation (HSCT) could provide effective cure of HIV-1 infected patients. Furthermore, gene modification by zinc finger nuclease (ZFN) demonstrated another successful result again. Despite the other studies for gene therapy by ∆32 genotype, there is another mutation -CCR5 ∆32/m303- that provides HIV-1 resistant. It is a heterozygote genotype for ∆32 and T→A point mutation at nucleotide 303. These results approved the key role of CCR5 gene. Conclusion: Recent studies showed immune gene therapy and cell therapy could provide effective cure for refractory disease like as HIV. Eradication of HIV-1 from immune system was not observed by HAART, because of reloading virus genome from latent reservoirs after stopping them. It is showed that CCR5 could induce natural resistant to HIV-1 infection by the new approaches based on stem cell transplantation and gene modifying.

Keywords: CCR5, HIV-1, stem cell, immune gene therapy, gene modification

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Authors: D. Deepak, N. Yagnesh Sharma

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Abrasive Water Jet (AWJ) machining is a relatively new nontraditional machine tool used in machining of fiber reinforced composite. The quality of machined surface depends on jet exit kinetic energy which depends on various operating and material parameters. In the present work the effect abrasive parameters such as its size, concentration and type on jet kinetic energy is investigated using computational fluid dynamics (CFD). In addition, the effect of these parameters on wall shear stress developed inside the nozzle is also investigated. It is found that for the same operating parameters, increase in the abrasive volume fraction (concentration) results in significant decrease in the wall shear stress as well as the jet exit kinetic energy. Increase in the abrasive particle size results in marginal decrease in the jet exit kinetic energy. Numerical simulation also indicates that garnet abrasives produce better jet exit kinetic energy than aluminium oxide and silicon carbide.

Keywords: abrasive water jet machining, jet kinetic energy, operating pressure, wall shear stress, Garnet abrasive

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Authors: Yingjeng James Li, Chih Chi Hsu, Chiao-Chih Hu

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Membrane electrode assemblies MEAs for proton exchange membrane PEM water electrolyzers were prepared by employing 175um perfluorosulfonic acid PFSA membranes as the PEM, onto which iridium oxide catalyst was coated on one side as the anode and platinum catalyst was coated on the other side as the cathode. The cathode catalyst ink was prepared so that the weight ratio of the catalyst powder to ionomer was 75:25, 70:30, 65:35, 60:40, and 55:45, respectively. Whereas, the ratio of catalyst powder to ionomer of the anode catalyst ink keeps constant at 50:50. All the MEAs have a catalyst coated area of 5cm*5cm. The test cell employs a platinum plated titanium grid as anode gas diffusion media; whereas, carbon paper was employed as the cathode gas diffusion media. The measurements of the MEA gases production rate were carried out by holding the cell voltage ranging from 1.6 to 2.8 volts at room temperature. It was found that the MEA with cathode catalyst to ionomer ratio of 65:35 gives the largest hydrogen production rate which is 2.8mL/cm2*min.

Keywords: electrolyzer, membrane electrode assembly, proton exchange membrane, ionomer, hydrogen

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Authors: Yves Mann Elate Lea Mbassi, Marie Solange Evehe Bebandoue, Wilfred Fon Mbacham

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Improving the catalytic performance of enzymes has been a long-standing theme of analytical biochemistry research. Induction of peroxidase activity by metals is a common reaction in higher plants. We thought that this increase in peroxidase activity may be due, on the one hand, to the stimulation of the gene expression of these enzymes but also to a modification of their chemical reactivity following the binding of some metal ions on their active site. We tested the effect of some metal salts (MgCl₂, MnCl₂, ZnCl₂, CaCl₂ and CuSO₄) on the activity and thermostability of peroxidase A6, a thermostable peroxidase that we discovered and purified in a previous study. The chromogenic substrate used was 3,3′,5,5′-tetramethylbenzidine. Of all the metals tested for their effect on A6, only magnesium and copper had a significant effect on the activity of the enzyme at room temperature. The Mann-Whitney test shows a slight inhibitory effect of activity by the magnesium salt (P = 0.043), while the activity of the enzyme is 5 times higher in the presence of the copper salt (P = 0.002). Moreover, the thermostability of peroxidase A6 is increased when calcium and copper salts are present. The activity in the presence of CaCl₂ is 8 times higher than the residual activity of the enzyme alone after incubation at 80°C for 10 min and 35 times higher in the presence of CuSO4 under the same conditions. In addition, manganese and zinc salts slightly reduce the thermostability of the enzyme. The activity and structural stability of peroxidase A6 can clearly be activated by Cu₂+, which therefore enhance the oxidation of 3,3′,5,5′-tetramethylbenzidine, which was used in this study as a chromogenic substrate. Ca₂+ likely has a more stabilizing function for the catalytic site.

Keywords: peroxidase activity, copper ions, calcium ions, thermostability

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Authors: Abdallah Habbab, Khaled Sekkoum, Nasser Belboukhari

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Objective: This study is designed to examine the chemical composition, antioxidant and antibacterial activities of the essential oil extracted from leaves of Vitex agnus-castus. Methods: The essential oils of dry leaves of Vitex agnus-castus L. were obtained by hydro-distillation, afforded oil in the yield of 5.5% and their volatile constituents were identified by GC/MS. Antioxidant activity of the sample was determined by test system DPPH. Antifungal activity was tested against three fungal strains (Aspergillus flavus, Penicillium escpansum and Aspergillus ochraceus) by direct contact method. Results: Forty-three compounds were identified, representing 98.02% of the oil. Major components of the oil were 1,8-cineole (18.27 %), caryophyllene (8.60 %), N-(M-fluorophenyl)-maleimide (6.30 %), (+)-epi-bicyclosesquiphellandrene (6.00 %), terpinen-4-ol (5.57 %), pyrrolo (3,2,1-jk) carbazole (5.43 %), caryophyllene oxide (4.79 %), and phenol (4.09 %). Conclusion: The chemical constituents in the essential oil from the locally grown Vitex agnus-castus were identified. Therefore, the essential oil of Vitex agnus-castus is an active candidate which would be used as antioxidant, or antifungal agent in new drugs preparation for therapy of diseases.

Keywords: Vitex agnus-castus, essential oil, GC/MS, DPPH, 1, 8-cineole

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Authors: Marcelo Costa Cardoso, Luciano Pessanha Moreira

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In this work, the plastic behaviour of cold-rolled zinc coated dual-phase steel sheets DP600 and DP800 grades is firstly investigated with the help of uniaxial, hydraulic bulge and Forming Limit Curve (FLC) tests. The uniaxial tensile tests were performed in three angular orientations with respect to the rolling direction to evaluate the strain-hardening and plastic anisotropy. True stress-strain curves at large strains were determined from hydraulic bulge testing and fitted to a work-hardening equation. The limit strains are defined at both localized necking and fracture conditions according to Nakajima’s hemispherical punch procedure. Also, an elasto-plastic localization model is proposed in order to predict strain and stress based forming limit curves. The investigated dual-phase sheets showed a good formability in the biaxial stretching and drawing FLC regions. For both DP600 and DP800 sheets, the corresponding numerical predictions overestimated and underestimated the experimental limit strains in the biaxial stretching and drawing FLC regions, respectively. This can be attributed to the restricted failure necking condition adopted in the numerical model, which is not suitable to describe the tensile and shear fracture mechanisms in advanced high strength steels under equibiaxial and biaxial stretching conditions.

Keywords: advanced high strength steels, forming limit curve, numerical modelling, sheet metal forming

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Authors: E. G. Zaki, M. A. Migahed, A. M. Al-Sabagh, E. A. Khamis

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Inhibition effect of four novel nonionic surfactants based on sulphonamide, of linear alkyl benzene sulphonic acid (LABS), was reacted with 1 mole triethylenetetramine, tetraethylenepentamine then Ethoxylation of amide X 65 type carbon steel in oil wells formation water under H2S environment was investigated by electrochemical measurements. Scanning electron microscopy (SEM) and energy dispersion X-ray (EDX) were used to characterize the steel surface. The results showed that these surfactants act as a corrosion inhibitor in and their inhibition efficiencies depend on the ethylene oxide content in the system. The obtained results showed that the percentage inhibition efficiency (η%) was increased by increasing the inhibitor concentration until the critical micelle concentration (CMC) reached The quantum chemistry calculations were carried out to study the molecular geometry and electronic structure of obtained derivatives. The energy gap between the highest occupied molecular orbital and lowest unoccupied molecular orbital has been calculated using the theoretical computations to reflect the chemical reactivity and kinetic stability of compounds.

Keywords: corrosion, surfactants, steel surface, quantum

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Authors: Jhen-Ting Huang, Chia-Chia Chang, Hu-Cheng Weng, An-Ya Lo

Abstract:

In this study, Co3O4-CNT-Graphene composite electrode was deposited by electrophoretic deposition (EPD) method, where micro polystyrene spheres (PSs) were added for co-deposition. Applied with heat treatment, a hierarchical porosity is left in the electrode which is beneficial for supercapacitor application. In terms of charge and discharge performance, we discussed the optimal CNT/Graphene ratio, macroporous ratio, and the effect of Co3O4 addition on electrode capacitance. For materials characterization, scanning electron microscope (SEM), X-ray diffraction, and BET were applied, while cyclic voltammetry (CV) and chronopotentiometry (CP) measurements, and Ragone plot were applied as in-situ analyses. Based on this, the effects of PS amount on the structure, porosity and their effect on capacitance of the electrodes were investigated. Finally, the full device performance was examined with charge-discharge and electron impedance spectrum (EIS) methods. The results show that the EPD coating with hierarchical porosity was successfully demonstrated in this study. As a result, the capacitance was greatly enhanced by 2.6 times with the hierarchical structure.

Keywords: supercapacitor, nanocarbon tub, graphene, metal oxide

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Authors: Harish Rajak, Kamlesh Raghuwanshi

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Histone deacetylase (HDAC) are promising target for cancer treatment. The panobinostat (Farydak; Novartis; approved by USFDA in 2015) and chidamide (Epidaza; Chipscreen Biosciences; approved by China FDA in 2014) are the novel HDAC inhibitors ratified for the treatment of patients with multiple myeloma and peripheral T cell lymphoma, respectively. On the other hand, two other HDAC inhibitors, Vorinostat (SAHA; approved by USFDA in 2006) and Romidepsin (FK228; approved by USFDA in 2009) are already in market for the treatment of cutaneous T-cell lymphoma. Several hydroxamic acid based HDAC inhibitors i.e., belinostat, givinostat, PCI24781 and JNJ26481585 are in clinical trials. HDAC inhibitors consist of three pharmacophoric features - an aromatic cap group, zinc binding group (ZBG) and a linker chain connecting cap group to ZBG. Herein, we report synthesis, characterization and biological evaluation of HDAC inhibitors possessing substituted isatin moiety as cap group which recognize the surface of active enzyme pocket and thiosemicarbazide moiety incorporated as linker group responsible for connecting cap group to ZBG (hydroxamic acid). Several analogues were found to inhibit HDAC and cellular proliferation of Hela cervical cancer cells with GI50 values in the micro molar range. Some of the compounds exhibited promising results in vitro antiproliferative studies. Attempts were also made to establish the structure activity relationship among synthesized HDAC inhibitors.

Keywords: HDAC inhibitors, hydroxamic acid derivatives, isatin derivatives, antiproliferative activity, docking

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Authors: Mohamed Gouda

Abstract:

Antibacterial wound dressings based on cellulose nanofibers containing different metal nanoparticles (CMC-MNPs) were synthesized using an electrospinning technique. First, the composite of carboxymethyl cellulose containing different metal nanoparticles (CMC/MNPs), such as copper nanoparticles (CuNPs), iron nanoparticles (FeNPs), zinc nanoparticles (ZnNPs), cadmium nanoparticles (CdNPs) and cobalt nanoparticles (CoNPs) were synthesized, and finally, these composites were transferred to the electrospinning process. Synthesized CMC-MNPs were characterized using scanning electron microscopy (SEM) coupled with high-energy dispersive X-ray (EDX) and UV-visible spectroscopy used to confirm nanoparticle formation. The SEM images clearly showed regular flat shapes with semi-porous surfaces. All MNPs were well distributed inside the backbone of the cellulose without aggregation. The average particle diameters were 29-39 nm for ZnNPs, 29-33 nm for CdNPs, 25-33 nm for CoNPs, 23-27 nm for CuNPs and 22-26 nm for FeNPs. Surface morphology, water uptake and release of MNPs from the nanofibers in water and antimicrobial efficacy were studied. SEM images revealed that electrospun CMC-MNPs nanofibers are smooth and uniformly distributed without bead formation with average fiber diameters in the range of 300 to 450 nm. Fiber diameters were not affected by the presence of MNPs. TEM images showed that MNPs are present in/on the electrospun CMC-MNPs nanofibers. The diameter of the electrospun nanofibers containing MNPs was in the range of 300–450 nm. The MNPs were observed to be spherical in shape. The CMC-MNPs nanofibers showed good hydrophilic properties and had excellent antibacterial activity against the Gram-negative bacteria Escherichia coli and the Gram-positive bacteria Staphylococcus aureus.

Keywords: electrospinning technique, metal nanoparticles, cellulosic nanofibers, wound dressing

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Authors: Maryam Ghavam Sadri, Kimia Moiniafshari

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Objectives: The prevalence of Autism in the world has taken on a growing trend. Autism is a neuro-developmental disorder that is identified at the age of three. Studies have been shown that nutritional management can control nutritional deficiencies in Autism. This review study aimed to assess the role of nutritional management strategies for Autism in children has been made. Methods: This review study was accomplished by using the keywords related to the topic, 68 articles were found (2000-2015) and finally 15 articles with criteria such as including dietary pattern, nutritional deficiencies and Autism controlling were selected. Results: The studies showed that intake of vitamins D, E, and calcium because of restricted diet (casein and gluten free) in autistic children is less than typically developing children (TYP) (p value ≤ 0.001) and as a result of restrictions on the consumption of fresh fruits and vegetables, vitamin C and magnesium intake is less than TYP children (p value ≤ 0.001). Autistic children also get omega-3 less than TYP children. Studies have shown that food sources rich in omega-3 can improve behavioral indicators, especially in reducing hyperactivity (95% CI = -2.2 - 5.2). Zinc deficiency in these children leads to a high serum level of mercury, lead and cadmium. As a result of the repetitive dietary pattern, Sodium intake in autistic children is more than TYP children (p value < 0.001).Because of low food variety in autistic children, healthy eating index (HEI) is less than TYP children (p value = 0.008).Food selectivity in Autism due to repetitive and restricted dietary pattern and nutritional deficiencies. Conclusion: Because of restricted (casein and gluten free) and repetitive dietary pattern, the intake of some micronutrients are denied in autistic children. The nutritional strategy programs appear to help controlling of Autism.

Keywords: autism, food selectivity, nutrient intake, nutritional strategies

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