Search results for: surface activity

Authors: Yung-Jin Weng, Chia-Chi Chang, Chun-Yu Tsai

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This paper is focused on the research of imprinting and replica molding of quasi-grey scale soft mold curved surface microstructure mold. In this paper, a magnetic photocuring forming system is first developed and built independently, then the magnetic curved surface microstructure soft mode is created; moreover, the magnetic performance of the magnetic curved surface at different heights is tested and recorded, and through experimentation and simulation, the magnetic curved surface microstructure soft mold is used in the research of quasi-grey scale soft mold curved surface microstructure imprinting and replica molding. The experimental results show that, under different surface curvatures and voltage control conditions, different quasi-grey scale array microstructures take shape. In addition, this paper conducts research on the imprinting and replica molding of photoresist composite magnetic powder in order to discuss the forming performance of magnetic photoresist, and finally, the experimental result is compared with the simulation to obtain more accurate prediction and results. This research is predicted to provide microstructure component preparation technology with heterogeneity and controllability, and is a kind of valid shaping quasi-grey scale microstructure manufacturing technology method.

Keywords: soft mold, magnetic, microstructure, curved surface

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Authors: Woogul Lee, Johnmarshall Reeve

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Learners’ perceived autonomy predicts learners’ interest, engagement, and learning. To understand these processes, we conducted an fMRI experiment. In this experiment, participants saw the national flag and were asked to rate how much they freely wanted to learn about that particular national flag. The participants then learned the characteristics of the national flag. Results showed that (1) the degree of participants’ perceived autonomy was positively correlated with the degree of insula activity, (2) participants’ early-trial insula activity predicted corresponding late-trial dorsolateral prefrontal cortex activity, and (3) the degree of dorsolateral prefrontal cortex activity was positively correlated with the degree of participants’ learning about the characteristics of the national flag. Results suggest that learners’ perceived autonomy predicts learning through the mediation of insula activity associated with intrinsic satisfaction and 'pure self' processes.

Keywords: insular cortex, autonomy, self-determination, dorsolateral prefrontal cortex

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Authors: Tannaz Alimardani, Amirhossein Moghanian, Morteza Elsa

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Bioactive glasses (BGs) are a group of surface-reactive biomaterials used in clinical applications as implants or filler materials in the human body to repair and replace diseased or damaged bone. Sol-gel technique was employed to prepare a SiO₂-CaO-P₂O₅ glass with a nominal composition of 58S BG with the addition of Sr and Li modifiers which imparts special properties to the BG. The effect of simultaneous addition of Sr and Li on bioactivity and biocompatibility, proliferation, alkaline phosphatase (ALP) activity of osteoblast cell line MC3T3-E1 and antibacterial property against methicillin-resistant Staphylococcus aureus (MRSA) bacteria were examined. BGs were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy before and after soaking the samples in the simulated body fluid (SBF) for different time intervals to characterize the formation of hydroxyapatite (HA) formed on the surface of BGs. Structural characterization indicated that the simultaneous presence of 5% Sr and 5% Li in 58S-BG composition not only did not retard HA formation because of the opposite effect of Sr and Li of the dissolution of BG in the SBF, but also stimulated the differentiation and proliferation of MC3T3-E1s. Moreover, the presence of Sr and Li on the dissolution of the ions resulted in an increase in the mean number of DAPI-labeled nuclei which was in good agreement with the live/dead assay. The result of antibacterial tests revealed that Sr and Li-substituted 58S bioactive glass exhibited a potential antibacterial effect against MRSA bacteria. Because of optimal proliferation and ALP activity of MC3T3-E1cells, proper bioactivity and high antibacterial potential against MRSA, BG-5/5 is suggested as a multifunctional candidate for bone tissue engineering.

Keywords: alkaline, alkaline earth, bioglass, co-doping, ion release

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Authors: Khiaira S. Hassan, Abbas S. Alwan, Muna K. Abbass

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This research aims to study the effect of the liquid nitriding and shot peening on the hardness, surface roughness, residual stress, microstructure and corrosion behavior of austenite stainless steel 316 L. Chemical surface heat treatment by liquid nitriding process was carried out at 500 °C for 1 h and followed by shot peening with using ball steel diameter of 1.25 mm in different exposure time of 10 and 20 min. Electrochemical corrosion test was applied in sea water (3.5% NaCl solution) by using potentostat instrument. The results showed that the nitride layer consists of a compound layer (white layer) and diffusion zone immediately below the alloy layer. It has been found that the mechanical treatment (shot peening) has led to the formation of compressive residual stresses in layer surface that increased the hardness of stainless steel surface. All surface treatment (nitriding and shot peening) processes have led to the formation of carbide of CrN in hard surface layer. It was shown that both processes caused an increase in surface hardness and roughness which increases with shot peening time. Also, the corrosion results showed that the liquid nitriding and shot peening processes increase the corrosion rate to values more than that of not treated stainless steel.

Keywords: stainless steel 316L, shot peening, nitriding, corrosion, hardness

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Authors: Aulina R. Rahmi, Farid Yuristiawan, Annisa Ibifadillah, Ummu H. Amri, Hidayati Gunawan

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Glass ionomer cement is one of the filling material that often used on the field of dentistry because it is relatively less expensive and mostly available. Restoration materials could undergo changes in their clinical properties such as changes in roughness of the restoration`s surface. An increase of surface roughness accelerates bacterial colonization and plaque maturation. In the oral cavity, GIC was exposed to various substances, such as toothpaste, an oral care product used during toothbrushing. One of the popular toothpaste is whitening toothpaste. Abrasive and chemical agents such as hydrogen peroxide in whitening toothpaste could increase the surface roughness of restorative materials. Objective: To determine the differences on the surface roughness of glass ionomer cement that was brushed with whitening and conventional toothpaste. Method: This study was done using experimental laboratory method with pre and post test design. There were 36 samples which were divided into 2 groups. The first group was brushed with whitening toothpaste and the second group was brushed with conventional toothpaste, each for 2 minutes. Surface roughness value of the specimens was measured by using Roughness Tester test. Result: The data was analyzed by using independent t-test and the result of this study showed there was a significant difference between the surface of glass ionomer cement which was brushed with whitening and conventional toothpaste (p=0,000). Conclusion: Glass ionomer cement that was brushed with whitening toothpaste produced more roughness than conventional toothpaste.

Keywords: glass ionomer cement, surface roughness, toothpaste, roughness tester

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Authors: Yuri A. Kalvachev, Totka D. Todorova

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Zeolite mordenite has been investigated as a transition metal support for the preparation of efficient catalysts in the oxidation of volatile organic compounds (VOCs). The highly crystalline mordenite samples were treated with hydrofluoric acid and ammonium fluoride to get hierarchical material with secondary porosity. The obtained supports by this method have a high active surface area, good diffusion properties and prevent the extraction of metal components during catalytic reactions. The active metal phases platinum and copper were loaded by impregnation on both mordenite materials (parent and acid treated counterparts). Monometalic Pt and Cu, and bimetallic Pt/Cu catalysts were obtained. The metal phases were fine dispersed as nanoparticles on the functional porous materials. The catalysts synthesized in this way were investigated in the reaction of complete oxidation of propane and benzene. Platinum, copper and platinum/copper were loaded and there catalytic activity was investigated and compared. All samples are characterized by X-ray diffraction analysis, nitrogen adsorption, scanning electron microscopy (SEM), X-ray photoelectron measurements (XPS) and temperature programed reduction (TPR). The catalytic activity of the samples obtained is investigated in the reaction of complete oxidation of propane and benzene by using of Gas Chromatography (GC). The oxidation of three organic molecules was investigated—methane, propane and benzene. The activity of metal loaded mordenite catalysts for methane oxidation is almost the same for parent and treated mordenite as a support. For bigger molecules as propane and benzene, the activity of catalysts based on treated mordenite is higher than those based on parent zeolite.

Keywords: metal loaded catalysts, mordenite, VOCs oxidation, zeolites

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Authors: Bita Mashayekhi, Mohammad Ara

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The purpose of this study is to provide some empirical evidence about implementing Activity-Based Costing (ABC) in the hospitality industry in Iran. For this purpose, we consider the Tabriz International Hotel as our sample hotel and then gather the relevant data from its cost accounting system in 2012. Then, we use ABC as our costing method and compare the cost of each service unit with that cost which had been extracted for the traditional costing method. The results show a different cost per unit for two methods. Also, because of its more precise and detailed provided information, an ABC system facilitates the decision-making process for managers on decisions related to profitability analysis, budgeting, pricing, and so on.

Keywords: Activity-Based Costing (ABC), activity, cost driver, hospitality industry

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Authors: Chia-Ting Chang, Chia-Yu Lin

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We report on the decisive role of iron phosphate (FePO₄), formed in-situ during the electrochemical characterization, played in the electrocatalytic activity, especially its oxygen tolerance of iron oxides towards H₂O₂ reduction. Iron oxides studied including, Nanorod arrays (NRs) of β-FeOOH, γ-Fe₂O₃, α-Fe₂O₃, α-Fe₂O₃ nanosheets (α-Fe₂O₃NS), α-Fe₂O₃ nanoparticles (α-Fe₂O₃NP), were synthesized using chemical bath deposition. The nanostructure was controlled simply by adjusting the composition of precursor solution and reaction duration for CBD process, whereas the crystal phase was controlled by adjusting the annealing temperature. It was found that iron phosphate (FePO₄) was deposited in-situ onto the surface of this nanostructured α-Fe₂O₃ during the electrochemical pretreatment in the phosphate electrolyte, and both FePO₄ and α-Fe₂O₃ showed the activity in catalysing the electrochemical reduction of H₂O₂. In addition, the interaction/compatibility between deposited FePO₄ and iron oxides has a decisive effect on the overall electrocatalytic activity of the resultant electrodes; FePO₄ only showed synergetic effect on the overall electrocatalytic activity of α-Fe₂O₃NR and α-Fe2O₃NS. Both α-Fe₂O₃NR and α-Fe₂O₃NS showed two reduction peaks in phosphate electrolyte containing H₂O₂, one being pH-dependent and related to the electrocatalytic properties of FePO₄, and the other one being pH-independent and only related to the intrinsic electrocatalytic properties of α-Fe₂O₃NR and α-Fe₂O₃NS. However, all iron oxides showed only one pH-independent reductive peak in non-phosphate electrolyte containing H₂O₂. The synergesitic catalysis exerted by FePO₄ with α-Fe₂O₃NR or α-Fe₂O₃NS providing additional oxygen-insensitive active site for H₂O₂ reduction, which allows their applications to electrochemical detection of H₂O₂ without the interference of O₂ involving in oxidase-catalyzed chemical processes.

Keywords: H₂O₂ reduction, Iron oxide, iron phosphate, O₂ tolerance

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Authors: E. Kilicay, Z. Karahaliloglu, B. Hazer, E. B. Denkbas

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In this study, we have prepared concanavaline A (ConA) functionalized curcumin (CUR) loaded PHBHHx (poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)) nanoparticles as a novel and efficient drug delivery system. CUR is a promising anticancer agent for various cancer types. The aim of this study was to evaluate therapeutic potential of curcumin loaded PHBHHx nanoparticles (CUR-NPs) and concanavaline A conjugated curcumin loaded NPs (ConA-CUR NPs) for ovarian cancer treatment. ConA was covalently connected to the carboxylic group of nanoparticles by EDC/NHS activation method. In the ligand attachment experiment, the binding capacity of ConA on the surface of NPs was found about 90%. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis showed that the prepared nanoparticles were smooth and spherical in shape. The size and zeta potential of prepared NPs were about 228±5 nm and −21.3 mV respectively. ConA-CUR NPs were characterized by FT-IR spectroscopy which confirmed the existence of CUR and ConA in the nanoparticles. The entrapment and loading efficiencies of different polymer/drug weight ratios, 1/0.125 PHBHHx/CUR= 1.25CUR-NPs; 1/0.25 PHBHHx/CUR= 2.5CUR-NPs; 1/0.5 PHBHHx/CUR= 5CUR-NPs, ConA-1.25CUR NPs, ConA-2.5CUR NPs and ConA-5CUR NPs were found to be ≈ 68%-16.8%; 55%-17.7 %; 45%-33.6%; 70%-15.7%; 60%-17%; 51%-30.2% respectively. In vitro drug release showed that the sustained release of curcumin was observed from CUR-NPs and ConA-CUR NPs over a period of 19 days. After binding of ConA, the release rate was slightly increased due to the migration of curcumin to the surface of the nanoparticles and the matrix integrities was decreased because of the conjugation reaction. This functionalized nanoparticles demonstrated high drug loading capacity, sustained drug release profile, and high and long term anticancer efficacy in human cancer cell lines. Anticancer activity of ConA-CUR NPs was proved by MTT assay and reconfirmed by apoptosis and necrosis assay. The anticancer activity of ConA-CUR NPs was measured in ovarian cancer cells (SKOV-3) and the results revealed that the ConA-CUR NPs had better tumor cells decline activity than free curcumin. The nacked nanoparticles have no cytotoxicity against human ovarian carcinoma cells. Thus the developed functionalized nanoformulation could be a promising candidate in cancer therapy.

Keywords: curcumin, curcumin-PHBHHx nanoparticles, concanavalin A, concanavalin A-curcumin PHBHHx nanoparticles, PHBHHx nanoparticles, ovarian cancer cell

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Authors: Shengzhu Cao, Hui Zhou, Gan Wu, Lanxi Wanhg, Kaifeng Zhang, Rui Wang, Hu Wang

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The functional micro and nanostructures, which can endow material surface with unique properties such as super-absorptance, hydrophobic and drag reduction. Recently, femtosecond laser ablation has been demonstrated to be a promising technology for surface functional micro and nanostructures fabrication. In this paper, using femtosecond laser ablation processing technique, we fabricated functional micro and nanostructures on Ti and Al alloy surfaces, test results showed that processed surfaces have 82%~96% absorptance over a broad wavelength range from ultraviolet to infrared. The surface function properties, which determined by micro and nanostructures, could be modulated by variation laser parameters. These functional surfaces may find applications in such areas as photonics, plasmonics, spaceborne devices, thermal radiation sources, solar energy absorbers and biomedicine.

Keywords: surface functional, micro and nanostructures, femtosecond laser, ablation

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Authors: Yongfang Deng, Dunwen Zuo

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An attempt is made here to join 2024 aluminum alloy plate by friction stir joining (FSJ) using different types of tools. Joint surface morphology was observed, and both arc line spacing and flash were measured. Study is carried out on the effect of pin, shoulder and eccentricity of the tool on the surface topography of the joint and the formation of the joint surface topography is analyzed. It is found that, eccentric squeezing action of the tool is the mainly motive power to form arc lines contour and flash structure. Little flash appears in the advancing side but with severe deformation, while the flash in the retreating side is heavy but with soft deformation. The pin of tool has a deep impact on the flash on the advancing side of the joints. Shoulder can widen the arc lines, refine arcs structure, reduce flash in the retreat side, but will increase the flash in the advancing side. Increasing the amount of eccentricity, it has litter effect on the arc line spacing but will destroy the arc lines morphology in the joint surface and promote the formation of filamentous flash structure in the joint.

Keywords: FSJ, surface morphology, tool, joint

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Authors: Karol Rodriguez-Peña, Martha L. Macias-Rubalcava, Leticia Rocha-Zavaleta, Sergio Sanchez

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A bioassay-guided study for anti-cancer compounds from endophytes of the Mexican medicinal plant Amphipteryygium adstringens resulted in the isolation of a streptomycete capable of producing a group of compounds with high cytotoxic activity. Microorganisms from surface sterilized samples of various sections of the plant were isolated and all the actinomycetes found were evaluated for their potential to produce compounds with cytotoxic activity against cancer cell lines MCF7 (breast cancer) and HeLa (cervical cancer) as well as the non-tumoural cell line HaCaT (keratinocyte). The most active microorganism was picked for further evaluation. The identification of the microorganism was carried out by 16S rDNA gene sequencing, finding the closest proximity to Streptomyces scabrisporus, but with the additional characteristic that the strain isolated in this study was capable of producing colorful compounds never described for this species. Crude extracts of dichloromethane and ethyl acetate showed IC50 values of 0.29 and 0.96 μg/mL for MCF7, 0.51 and 1.98 μg/mL for HeLa and 0.96 and 2.7 μg/mL for HaCaT. Scaling the fermentation to 10 L in a bioreactor generated 1 g of total crude extract, which was fractionated by silica gel open column to yield 14 fractions. Nine of the fractions showed cytotoxic activity. Fraction 4 was chosen for subsequent purification because of its high activity against cancerous cell lines, lower activity against keratinocytes. HPLC-UV-MS/ESI was used for the evaluation of this fraction, finding at least 10 different compounds with high values of m/z (≈588). Purification of the compounds was carried out by preparative thin-layer chromatography. The prevalent compound was Steffimycin B, a molecule known for its antibiotic and cytotoxic activities and also for its low solubility in aqueous solutions. Along with steffimycin B, another five compounds belonging to the steffimycin family were isolated and at this moment their structures are being elucidated, some of which display better solubility in water: an attractive property for the pharmaceutical industry. As a conclusion to this study, the isolation of endophytes resulted in the discovery of a strain capable of producing compounds with high cytotoxic activity that need to be studied for their possible utilization.

Keywords: amphipterygium adstringens, cytotoxicity, streptomyces scabrisporus, steffimycin

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Authors: A. Khan, M. Hussain, S. Afgun

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In the present work, the effect of the surface integration on the piezoelectric properties of zinc oxide (ZnO) nanorods has been investigated. ZnO nanorods were grown by using aqueous chemical growth method on two samples of graphene coated pet plastic substrate. First substrate’s surface was integrated with ZnO nanoparticles while the other substrate was used without ZnO nanoparticles. Various important parameters were analyzed, the growth density and morphological analysis were taken into account through surface scanning electron microscopy; it was observed that the growth density of nanorods on the integrated surface was much higher than the nonintegrated substrate. The crystal quality of growth orientation was analyzed by X-ray diffraction technique. Mechanical stability of ZnO nanorods on an integrated substrate was more appropriate than the nonintegrated substrate. The generated amount of piezoelectric potential from the integrated substrate was two times higher than the nonintegrated substrate. This shows that the layer of nanoparticles plays a crucial role in the enhancement of piezoelectric potential. Besides this, it also improves the performance of fabricated devices like its mechanical stability and piezoelectric properties. Additionally, the obtained results were compared with the other two samples used for the growth of ZnO nanorods on silver coated glass substrates for similar measurement. The consistency of the results verified the importance of surface integration effect. This study will help us to fabricate improved performance devices by using surface integrated substrates.

Keywords: ZnO nanorods, surface integration, mechanical properties, harvesting piezoelectricity

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Authors: Arindam Pramanik, Parimal Karmakar

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We have explored the synergistic anti-cancer activity of copper ion and acetylacetone complex containing 1,3 diketone group (like curcumin) in metallorganic compound “Copper acetylacetonate” (CuAA). The cytotoxicity mechanism of CuAA complex was evaluated on various cancer cell lines in vitro. Among these, reactive oxygen species (ROS), glutathione level (GSH) in the cell was found to increase. Further mitochondrial membrane damage was observed. The fate of cell death was found to be induced by apoptosis. For application purpose, we have developed a novel biodegradable, non-toxic polymer-based nanoparticle which has hydrophobically modified core for loading of the CuAA. Folic acid is conjugated on the surface of the polymer (chitosan) nanoparticle for targeting to cancer cells for minimizing toxicity to normal cells in-vivo. Thus, this novel drug CuAA has an efficient anticancer activity which has been targeted specifically to cancer cells through polymer nanoparticle.

Keywords: anticancer, apoptosis, copper nanoparticle, targeted drug delivery

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Authors: Yufan Mu

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The selective depression of pyrite in the flotation of copper minerals is difficult due to the activation of pyrite surface by copper ions. Novel depressants for pyrite are needed to responsibly extract copper resources for a greener and cleaner future. In this paper, the non-toxic sodium alginate was employed as a depressant to selectively separate chalcopyrite from pyrite in flotation using potassium amyl xanthate as the collector. The results from flotation tests showed that sodium alginate significantly depressed pyrite flotation while had slight influence on chalcopyrite flotation. The adsorption tests showed that the adsorption amount of sodium alginate on pyrite surface was much higher than that on chalcopyrite surface. The pre-adsorbed sodium alginate could effectively hinder the subsequent adsorption of collector on pyrite surface, thereby inhibiting pyrite flotation. The selective adsorption of sodium alginate on pyrite surface was caused by the interactions between the activating cuprous ions on pyrite surface and the carboxyl groups in sodium alginate. The paper shows that sodium alginate is a promising depressant for pyrite in the flotation of chalcopyrite.

Keywords: chalcopyrite flotation, pyrite depression, sodium alginate, copper-activated pyrite, adsorption

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Authors: Ashish Ankus Yerunkar, Ravi Terkar

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Study aimed at evaluating the best process environment which could simultaneously satisfy requirements of both quality as well as productivity with special emphasis on reduction of cutting tool flank wear, because reduction in flank wear ensures increase in tool life. The predicted optimal setting ensured minimization of surface roughness. Purpose of this paper is focused on the analysis of optimum cutting conditions to get lowest surface roughness in turning SCM 440 alloy steel by Taguchi method. Design for the experiment was done using Taguchi method and 18 experiments were designed by this process and experiments conducted. The results are analyzed using ANOVA method. Taguchi method has depicted that the depth of cut has significant role to play in producing lower surface roughness followed by feed. The Cutting speed has lesser role on surface roughness from the tests. The vibrations of the machine tool, tool chattering are the other factors which may contribute poor surface roughness to the results and such factors ignored for analyses. The inferences by this method will be useful to other researches for similar type of study and may be vital for further research on tool vibrations, cutting forces etc.

Keywords: surface roughness (ra), machining, dry turning, taguchi method, turning process, anova method, mahr perthometer

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Authors: Abdelmalek Arrouf

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This article sets up a cognitive schema of the architectural designing activity. It begins by outlining, theoretically, an a priori model of its general cognitive mechanisms. The obtained theoretical framework represents the designing activity as a complex system composed of three interrelated subsystems of cognitive actions: a subsystem of meaning production, one of morphology production and finally a subsystem of navigation between the two formers. A protocol analysis that uses statistical and informational tools is then used to measure the validity of the built schema. The model thus achieved shows that the designer begins by conceiving abstract meanings, which he then translates into shapes. That’s why we call it a semio-morphic model of the designing activity.

Keywords: designing actions, model of the design process, morphosis, protocol analysis, semiosis

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Authors: Andreas Savvides, Chloe Kadi

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The objective of this study is to investigate how the planning and design of open parks within neighborhoods and communities can promote physical activity in order to enhance the health of the local population. An extensive literature review was conducted for studies regarding the relationship between health and physical activity and the park characteristics that can promote physical activity among people. The findings of the literature review were then compared and analysed, in order to identify the main characteristics of urban parks that can promote physical activity and enhance public health. In order to find out how the characteristics identified in the literature were applied in real life, an analysis of three existing parks in three different countries was conducted. The parks, apart from their geographical location, also vary in size and layout. The parks were chosen because they are urban open parks and they include facilities for physical activity.

Keywords: urban planning, active living behaviour, open parks, sustainable mobility

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Authors: Sandeep Kaushal

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Tetracycline (TC) is a widespread antibiotic that is utilised in a multitude of countries, particularly China, India, and the United States of America, due to its low cost and potency in boosting livestock production. Unfortunately, certain antibiotics can be hazardous to living beings due to metal complexation and aggregation, which can lead to teratogenicity and carcinogenicity. Heterojunction photocatalysts are promising for the effective removal of pollutants like antibiotics. Herein, a simple, economical, and pollution-less hydrothermal technique was used to construct SnO₂/MnV₂O₆heterojunction with varying amounts of tin dioxide (SO₂). Various sophisticated techniques like XRD, FTIR, XPS, FESEM, HRTEM, and PLand Raman spectroscopy demonstrated the successful synthesis of SnO₂/MnV₂O₆ heterojunction photocatalysts.BET surface area analysis revealed that the as-synthesized heterojunction has a favorable surface area and surface properties for efficacious degradation of tetracycline. Under the direct sunlight exposure, the SnO₂/MnV₂O₆ heterojunction possessed superior photodegradation activity toward TC than the pristine SnO₂ and MnV2O6owing to their excellent adsorption abilities suitable band positions, large surface areas along with the effective charge-transfer ability of the heterojunction. The SnO₂/MnV₂O₆ heterojunction possessed extraordinary efficiency for the photocatalytic degradation of TC antibiotic (98% in 60 min) with an apparent rate constant of 0.092 min–1. In the degradation experiments, photocatalytic activities of as-synthesized heterojunction were studied by varying different factors such as time contact, catalyst dose, and solution pH. The role of reactive species in antibiotics was validated by radical scavenging studies, which indicated that.OH, radical has a critical role in photocatalytic degradation. Moreover, liquid chromatography-mass spectrometry (LC-MS) investigations were employed to anticipate a plausible mechanism for TC degradation.

Keywords: photocatalytic degradation, tetracycline, heterojunction, LC-MS

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Authors: Sawale Pravin Digambar, G. R. Patil, Shaik Abdul Hussain

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Terminalia arjuna (TA), an important medicinal plant in Indian System of Medicine, is specifically recognized for its recuperative effect on heart ailments. Alcoholic extract of TA (both free and encapsulated) was incorporated into milk to obtain functional dairy beverages. The respective beverages were appropriately flavored and optimized using response surface methodology to improve the sensory appeal. The beverages were evaluated for their compositional, anti-oxidative and various other physico-chemical aspects. Addition of herb (0.3%) extract to flavoured dairy drink (Drink 1) resulted in significantly lowered (p>0.05) HMF content and increased antioxidant activity, total phenol content as compared with control (Control 1). Subsequently, a significant (p>0.05) increase in acidity and sedimentation was also observed. Encapsulated herb (1.8%) incorporated drink (Drink 2) had significantly (P>0.05) enhanced HMF value and decreased antioxidant activity, phenol content as compared to herb added vanilla chocolate dairy drink (Drink 1). It can be concluded that addition of encapsulated TA extract and non-encapsulated TA extract to chocolate dairy drink at 0.3% concentration altered the functional properties vanilla chocolate dairy drink which could be related to the interaction of herb components such as polyphenol with milk protein or maltodextrin/ gum Arabic matrix.

Keywords: Terminalia arjuna, encapsulate, antioxidant activity, physicochemical study

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Authors: S. Farid F. Mojtahedi, Ali Khosravi, Behnaz Naeimian, S. Adel A. Hosseini

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Land subsidence is a gradual settling or sudden sinking of the land surface from changes that take place underground. There are different causes of land subsidence; most notably, ground-water overdraft and severe weather conditions. Subsidence of the land surface due to ground water overdraft is caused by an increase in the intergranular pressure in unconsolidated aquifers, which results in a loss of buoyancy of solid particles in the zone dewatered by the falling water table and accordingly compaction of the aquifer. On the other hand, exploitation of underground water may result in significant changes in degree of saturation of soil layers above the water table, increasing the effective stress in these layers, and considerable soil settlements. This study focuses on estimation of soil moisture at surface using different methods. Specifically, different methods for the estimation of moisture content at the soil surface, as an important term to solve Richard’s equation and estimate soil moisture profile are presented, and their results are discussed through comparison with field measurements obtained from Yanco1 station in south-eastern Australia. Surface soil moisture is not easy to measure at the spatial scale of a catchment. Due to the heterogeneity of soil type, land use, and topography, surface soil moisture may change considerably in space and time.

Keywords: artificial neural network, empirical method, remote sensing, surface soil moisture, unsaturated soil

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Authors: Collins Chiemeke, Stephen Ibe, Godwin Onyedim

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This research work on high-resolution seismic tomography method was carried out with the aim of investigating how near-surface geology influences the initial distribution of infrastructural development in an area like Otuoke and its environs. To achieve this objective, seismic tomography method was employed. The result revealed that the overburden (highly-weathered layer) thickness ranges from 27 m to 50 m within the survey area, with an average value of 37 m. The 3D surface analysis for the overburden thickness distribution within the survey area showed that the thickness of the overburden is more in regions with less infrastructural development, and least in built-up areas. The range of velocity distribution from the surface to within a depth of 5 m is about 660 m/s to 1160 m/s, with an average value of 946 m/s. The 3D surface analysis of the velocity distribution also revealed that the areas with large infrastructural development are characterized with large velocity values compared with the undeveloped regions that has average low-velocity values. Hence, one can conclusively say that the initial settlement of Otuoke and its environs and the subsequent infrastructural development was influenced by the underlying near surface geology (rigid earth), among other factors.

Keywords: geology, seismic, infrastructural, near-surface

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Authors: Ahmed Esmael, Ali El Shrif

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In this study the instability problem of a modified Taylor-Couette flow between two vertical coaxial cylinders of radius R1, R2 is considered. The modification is based on the wavy shape of the inner cylinder surface, where inner cylinders with different surface amplitude and wavelength are used. The study aims to discover the effect of the inner surface geometry on the instability phenomenon that undergoes Taylor-Couette flow. The study reveals that the transition processes depends strongly on the amplitude and wavelength of the inner cylinder surface and resulting in flow instabilities that are strongly different from that encountered in the case of the classical Taylor-Couette flow.

Keywords: hydrodynamic instability, Modified Taylor-Couette Flow, turbulence, Taylor vortices

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Authors: Elitsa N. Kolentsova, Dimitar Y. Dimitrov, Petya Cv. Petrova, Georgi V. Avdeev, Diana D. Nihtianova, Krasimir I. Ivanov, Tatyana T. Tabakova

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Recently, copper and manganese-containing systems are recognized as active and selective catalysts in many oxidation reactions. The main idea of this study is to obtain more information about γ-Al₂O₃ supported Cu-La catalysts and to evaluate their activity to simultaneous oxidation of CO, CH₃OH and dimethyl ether (DME). The catalysts were synthesized by impregnation of support with a mixed aqueous solution of nitrates of copper, manganese and lanthanum under different conditions. XRD, HRTEM/EDS, TPR and thermal analysis were performed to investigate catalysts’ bulk and surface properties. The texture characteristics were determined by Quantachrome Instruments NOVA 1200e specific surface area and pore analyzer. The catalytic measurements of single compounds oxidation were carried out on continuous flow equipment with a four-channel isothermal stainless steel reactor in a wide temperature range. On the basis of XRD analysis and HRTEM/EDS, it was concluded that the active component of the mixed Cu-Mn-La/γ–alumina catalysts strongly depends on the Cu/Mn molar ratio and consisted of at least four compounds – CuO, La₂O₃, MnO₂ and Cu_1.5Mn_1.5O₄. A homogeneous distribution of the active component on the carrier surface was found. The chemical composition strongly influenced catalytic properties. This influence was quite variable with regards to the different processes.

Keywords: Cu-Mn-La oxide catalysts, carbon oxide, VOCs, deep oxidation

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Authors: Weinian Wang, Joseph C. Chen

Abstract:

The objective of this research is to optimize the process of cutting cylindrical workpieces utilizing live tooling on a HAAS ST-20 lathe. Surface roughness (Ra) has been investigated as the indicator of quality characteristics for machining process. Aluminum alloy was used to conduct experiments due to its wide range usages in engineering structures and components where light weight or corrosion resistance is required. In this study, Taguchi methodology is utilized to determine the effects that each of the parameters has on surface roughness (Ra). A total of 18 experiments of each process were designed according to Taguchi’s L9 orthogonal array (OA) with four control factors at three levels of each and signal-to-noise ratios (S/N) were computed with Smaller the better equation for minimizing the system. The optimal parameters identified for the surface roughness of the turning operation utilizing live tooling were a feed rate of 3 inches/min(A3); a spindle speed of 1300 rpm(B3); a 2-flute titanium nitrite coated 3/8” endmill (C1); and a depth of cut of 0.025 inches (D2). The mean surface roughness of the confirmation runs in turning operation was 8.22 micro inches. The final results demonstrate that Taguchi methodology is a sufficient way of process improvement in turning process on surface roughness.

Keywords: CNC milling operation, CNC turning operation, surface roughness, Taguchi parameter design

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Authors: Nurul Na'imy Wan, Mohamad Sazali Said, Jaharah Ab. Ghani, Mohd Asri Selamat

Abstract:

This paper presents the surface roughness of the Aluminium silicon alloy (AlSi) matrix composite which has been reinforced with aluminium nitride (AlN), with three types of carbide inserts. Experiments were conducted at various cutting speeds, feed rates, and depths of cut, according to the Taguchi method, using a standard orthogonal array L27 (34). The signal-to-noise (S/N) ratio and analysis of variance are applied to study the characteristic performance of machining parameters in measuring the surface roughness during the milling operation. The analysis of results, using the Taguchi method concluded that a combination of low feed rate, medium depth of cut, low cutting speed, and insert TiB2 give a better value of surface roughness. From Taguchi method, it was found that cutting speed of 230m/min, feed rate of 0.4 mm/tooth, depth of cut of 0.5mm and type of insert of TiB2 were the optimal machining parameters that gave the optimal value of surface roughness.

Keywords: AlSi/AlN Metal Matrix Composite (MMC), surface roughness, Taguchi method

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Authors: Qingtao Yu, Guojia Ma

Abstract:

Approaches to microwave absorption and low infrared emissivity are often conflicting, as the low-emissivity layer, usually consisting of metals, increases the reflection of microwaves, especially in high frequency. In this study, an infrared-radar compatible stealth surface was fabricated by first depositing a layer of low-emissivity metal film on the surface of a layer of radar-absorbing material. Then, ultrafast laser was used to generate patterns on the metal film, forming a frequency selective surface. With proper pattern design, while the majority of the frequency selective surface is covered by the metal film, it has relatively little influence on the reflection of microwaves between 2 to 18 GHz. At last, structures on the radar-absorbing layer were fabricated by ultra-fast laser to further improve the absorbing bandwidth of the microwave. This study demonstrates that the compatibility between microwave absorption and low infrared emissivity can be achieved by properly designing patterns and structures on the metal film and the radar-absorbing layer accordingly.

Keywords: frequency selective surface, infrared-radar compatible, low infrared emissivity, radar-absorbing material, patterns, structures

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Authors: Wen-Jay Lee, Kuo-Ning Chiang

Abstract:

The graphene binding with silicon substrate has apparently Schottky barriers property, which can be used in the application of solar cell and light source. Because graphene has only one atom layer, the atomistic structure of graphene binding with the silicon surface plays an important role to affect the properties of graphene. In this work, temperature effect on the morphology of graphene sheet attached on different crystal planes of silicon substrates are investigated by Molecular dynamics (MD) (LAMMPS, developed by Sandia National Laboratories). The results show that the covered graphene sheet would cause the structural deformation of the surface Si atoms of stubtrate. To achieve a stable state in the binding process, the surface Si atoms would adjust their position and fit the honeycomb structure of graphene after the graphene attaches to the Si surface. The height contour of graphene on different plane of silicon surfaces presents different pattern, leading the local residual stress at the interface. Due to the high density of dangling bond on the Si (111)7x7 surface, the surface of Si(111)7x7 is not matching with the graphene so well in contrast with Si(100)2x1and Si(111)2x1. Si(111)7x7 is found that only partial silicon adatoms are rearranged on surface after the attachment when the temperature is lower than 200K, As the temperature gradually increases, the deformation of surface structure becomes significant, as well as the residue stress. With increasing temperature till the 815K, the graphene sheet begins to destroy and mixes with the silicon atoms. For the Si(100)2x1 and Si(111)2x1, the silicon surface structure keep its structural arrangement with a higher temperature. With increasing temperature, the residual stress gradually decrease till a critical temperatures. When the temperature is higher than the critical temperature, the residual stress gradually increases and the structural deformation is found on the surface of the Si substrates.

Keywords: molecular dynamics, graphene, silicon, Schottky barriers, interface

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Authors: Lei Ren, Michael Hartnett, Stephen Nash

Abstract:

The abundant measured surface current from HF radar system in coastal area is assimilated into model to improve the modeling forecasting ability. A simple sequential data assimilation scheme, Direct Insertion (DI), is applied to update model forecast states. The influence of Direct Insertion data assimilation over time is analyzed at one reference point. Vector maps of surface current from models are compared with HF radar measurements. Root-Mean-Squared-Error (RMSE) between modeling results and HF radar measurements is calculated during the last four days with no data assimilation.

Keywords: data assimilation, CODAR, HF radar, surface current, direct insertion

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Authors: Alvaro Ramírez, Martín Muñoz-Morales, Ester López- Fernández, Javier Llanos, C. Ania

Abstract:

Carbon blacks are value-added materials typically produced through the incomplete combustion or thermal decomposition of hydrocarbons. Traditionally, they have been used as catalysts in many different applications, but in the last decade, their potential in green chemistry has gained significant attention. Among them, the electrochemical production of H₂O₂ has attracted interest because of their properties as high oxidant capacity or their industrial interest as a bleaching agent. Carbon blacks are commonly used in this application in a catalytic ink that is drop-casted on supporting electrodes and acts as catalysts for the electrochemical production of H₂O₂ through oxygen reduction reaction (ORR). However, the different structural and electrochemical behaviors of each type of carbon black influence their applications. In this line, the term ‘carbon black’, has to be considered as a generic name that does not guarantee any physicochemical properties if any further description is mentioned. In fact, different specific surface area (SSA), surface functional groups, porous structure, and electro catalysts effect seem very important for electrochemical applications, and considerable differences were found during the analysis of four types of carbon blacks. Thus, the aim of this work is to evaluate the influence of SSA, porous structure, oxygen functional groups, and structural defects to differentiate among these carbon blacks (e.g. Vulcan XC72, Superior Graphite Co, Printex XE2, and Prolabo) for H₂O₂ production via ORR, using carbon paper as electrode support with improved selectivity and efficiency. Results indicate that the number and size of pores, along with surface functional groups, are key parameters that significantly affect the overall process efficiency.

Keywords: carbon blacks, oxygen reduction reaction, hydrogen peroxide, porosity, surface functional groups

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