Search results for: microscope

Authors: Yousof Farrag, Sara Malmir, Rebeca Bouza, Maite Rico, Belén Montero, Luís Barral

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Biopolymers are being extensively studied in the last years as a replacement of the conventional petroleum derived polymers, especially in packaging industry. They are natural, biodegradable materials. However, the lack of good mechanical and barrier properties is a problem in the way of this replacement. One of the most abundant biopolymers in the nature is the starch, its renewable, biocompatible low cost polysaccharide, it can be obtained from wide variety of plants, it has been used in food, packaging and other industries. This work is focusing on the production a high yield of starch nanoparticles via nanoprecipitation, to be used as reinforcement filling of biopolymer packaging matrices made of different types of starch improving their mechanical and barrier properties. Wheat and corn starch solutions were prepared in different concentrations. Absolute ethanol, acetone and different concentrations of hydrochloric acid were added as antisolvents dropwise under different amplitudes of sonication and different speeds of stirring, the produced particles were analyzed with dynamic light scattering DLS and scanning electron microscope SEM getting the morphology and the size distribution to study the effect of those factors on the produced particles. DLS results show that we have nanoparticles using low concentration of corn starch (0.5%) using 0.1M HCl as antisolvent, [Z average: 209 nm, PDI: 0,49], in case of wheat starch, we could obtain nanoparticles [Z average: 159 nm, PDI: 0,45] using the same starch solution concentration together with absolute ethanol as antisolvent.

Keywords: biopolymers, nanoparticles, DLS, starch

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

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In this study, carbon mesoporous material, CMK-3, was adopted as supporting material for electroactive polymerspolyaniline (PANI), polyaniline, for supercapacitor application, where hydroquinone (HQ) was integrated to enhance the redox reaction of PANI. The results show that the addition of PANI improves the capacitance of electrode from 89 F/g (CMK-3) to 337 F/g (PANI/CMK-3), the addition of HQ furtherly improves the capacitance to 463 F/g (PANI/CMK-3/HQ). The PANI provides higher energy density and also acts as binder of the electrode; the CMK-3 provides higher electron double layer capacitance EDLC and stabilize the polyaniline by its highly porosity. With the addition of HQ, the capacitance of PANI/CMK-3 was further enhanced. In-situ analyses including cyclic voltammetry (CV), chronopotentiometry (CP), electron impedance spectrum (EIS) analyses were applied for electrode performance examination. For materials characterization, the crystal structure, morphology, microstructure, and porosity were examined by X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscopy (TEM), and 77K N2 adsorption/desorption analyses, respectively. The effects of electrolyte pH value, PANI polymerization time, HQ concentration, and PANI/CMK-3 ratio on capacitance were discussed. The durability was also studied by long-term operation test. The results show that PANI/CMK-3/HQ with great potential for supercapacitor application. Finally, the potential of all-solid PANI/CMK-3/HQ based supercapacitor was successfully demonstrated.

Keywords: CMK3, PANI, redox electrolyte, solid supercapacitor

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Authors: Esa Abiso Godana, Qiya Yang, Kaili Wang, Zhang Hongyin, Xiaoyun Zhang, Lina Zhao

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Blue mold decay caused by Penicillium expansum is among the recent identified diseases of grapes (Vitis vinifera). The increasing concern about use of chemical substance and pesticide in postharvest fruit push the trends of research toward biocontrol strategies which are more sustainable and ecofriendly. In this study, we determined the biocontrol efficacy of Pichia anomala alone and supplemented with 1% chitosan in the grapefruit against blue mold disease caused by P. expansum. The result showed that 1% chitosan better enhances the biocontrol efficacy P. anomala. Chitosan (1% w/v) also improved the number of population of P. anomala in grape wounds, surface and on nutrient yeast dextrose broth (NYDB). P. anomala supplemented with 1% w/v chitosan significantly reduced the disease incidence, lesion diameter and natural decay of grapefruits without affecting the fruit quality as compared to the control. The scanned electron microscope (SEM) concisely illustrates how the high number of yeast cells on the wounds reduced the growth of P. expansum. P. anomala alone or P. anomala supplemented with 1% w/v chitosan are presented as a potential biocontrol alternative against the postharvest blue mold of grapefruit.

Keywords: biocontrol, Pichia anomala, chitosan, Penicillium expansum, grape

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Authors: Sihem Kadem, Ratiba Irinislimane, Naima Belhaneche

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The natural resistance to biodegradation of polymeric materials prepared from petroleum-based source and the management of their wastes in the environment are the driving forces to replace them by other biodegradable materials from renewable resources. For that, in this work new biocomposites materials have been synthesis from sunflower oil (Helianthus annuus) and alfa plants (Stipatenacissima) as natural based resources. The sunflower oil (SFO) was chemically modified via epoxidation then acrylation reactions to obtain acrylated epoxidized sunflower oil resin (AESFO). The AESFO resin was then copolymerized with styrene as co-monomer in the presence of boron trifluoride (BF3) as cationic initiator and cobalt octoate (Co) as catalyst. The alfa fibers were treated with alkali treatment (5% NaOH) before been used as bio-reinforcement. Biocomposites were prepared by mixing the resin with untreated and treated alfa fibers at different percentages. A biodegradation study was carried out for the synthesized biocomposites in a solid medium (burial in the soil) by evaluated, first, the loss of mass, the results obtained were reached between 7.8% and 11% during one year. Then an observation under an optical microscope was carried out, after one year of burial in the soil, microcracks, brown and black spots were appeared on the samples surface. This results shows that the synthesized biocomposites have a great aptitude for biodegradation.

Keywords: alfa fiber, biocomposite, biodegradation, soil, sunflower oil

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Authors: Donna L. Roberts

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Beyond the fundamental question of what is (and what isn’t) art, one then moves to the question of what about art, or a specific artwork, matters. If there is an agreement that something is art, the next step is to answer the obvious, ‘So what? What does it mean?’ In answering these questions, one must decide how to focus the proverbial microscope –i.e., what level of perspective is relevant as a point of view for this analysis- the artwork itself, the artist’s intention, the viewer’s interpretation, the artwork’s reflection of the larger artistic movement, the social, political, and historical context of art? One must determine what product and what contexts are meaningful when experiencing and interpreting art. Is beauty really in the eye of the beholder? Or is it more important what the creator was trying to say than what the critic or observer heard? The fact that so many artists –from Rembrandt to Van Gogh to Picasso- include among their works at least one self-portrait seems to scream their point –I matter. But, Is a piece more impactful because of the persona behind it? Or does that persona impose limits and close one’s mind to the possibilities of interpretation? In the popular art text visual culture, Richard Howells argues against a biographical focus on the artist in the analysis of art. Similarly, abstract expressionist Mark Rothko, along with several of his contemporaries of the genre, often did not title his paintings for the express purpose of not imposing a specific meaning or interpretation on the piece. And yet, he once said, ‘The people who weep before my pictures are having the same religious experience I had when I painted them,’ thus alluding to a desire for a shared connection and revelation. This research analyzes the arguments for differing levels of interpretation and points of view when considering a work of art and/or the artist who created it.

Keywords: art analysis, art interpretation, art theory, artistic perspective

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Authors: Juiwen Liang, Choliang Chung

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In this study, the silicon-base oxide nanofibers with hollow structure were prepared using single-nozzle electrospinning and heat treatment. Firstly, precursor solution was prepared: the Polyvinylpyrrolidone (PVP) and Tetraethyl orthosilicate (TEOS) dissolved in ethanol and to make sure the concentration of solution in appropriate using single-nozzle electrospinning to produce the nanofibers. Secondly, control morphology of the electrostatic spinning nanofibers was conducted, and design the temperature profile to created hollow nanofibers, exploring the morphology and properties of nanofibers. The characterized of nanofibers, following instruments were used: Atomic force microscopy (AFM), Field Emission Scanning Electron Microscope (FE-SEM), Transmission electron microscopy (TEM), Photoluminescence (PL), X-ray Diffraction (XRD). The AFM was used to scan the nanofibers, and 3D Graphics were applied to explore the surface morphology of fibers. FE-SEM and TEM were used to explore the morphology and diameter of nanofibers and hollow nanofiber. The excitation and emission spectra explored by PL. Finally, XRD was used for identified crystallization of ceramic nanofibers. Using electrospinning technique followed by subsequent heat treatment, we have successfully prepared silicon-base oxide nanofibers with hollow structure. Thus, the microstructure and morphology of electrostatic spinning silicon-base oxide hollow nanofibers were explored. Major characteristics of the nanofiber in terms of crystalline, optical properties and crystal structure were identified.

Keywords: electrospinning, single-nozzle, hollow, nanofibers

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Authors: Jiyaul Haque, Vandana Srivastava, M. A. Quraishi

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The amino acids based corrosion inhibitors 2-(3-(carboxymethyl)-1H-imidazol-3-ium-1-yl) acetate (Z-1),2-(3-(1-carboxyethyl)-1H-imidazol-3-ium-1-yl) propanoate (Z-2) and 2-(3-(1-carboxy-2-phenylethyl)-1H-imidazol-3-ium-1-yl)-3- phenylpropanoate (Z-3) were synthesized by the reaction of amino acids, glyoxal and formaldehyde, and characterized by the FTIR and NMR spectroscopy. The corrosion inhibition performance of synthesized inhibitors was studied by electrochemical (EIS and PDP), surface and DFT methods. The results show, the studied Z-1, Z-2 and Z-3 are effective inhibitors, showed the maximum inhibition efficiency of 88.52 %, 89.48 and 96.08% at concentration 200ppm, respectively. The results of potentiodynamic polarization (PDP) study showed that Z-1 act as a cathodic inhibitor, while Z-2 and Z-3 act as mixed type inhibitors. The results of electrochemical impedance spectroscopy (EIS) studies showed that zwitterions inhibit the corrosion through adsorption mechanism. The adsorption of synthesized zwitterions on the mild steel surface was followed the Langmuir adsorption isotherm. The formation of zwitterions film on mild steel surface was confirmed by the scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDX). The quantum chemical parameters were used to study the reactivity of inhibitors and supported the experimental results. An inhibitor adsorption model is proposed.

Keywords: electrochemical impedance spectroscopy, green corrosion inhibitors, mild steel, SEM, quantum chemical calculation, zwitterions

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Authors: Juan Manuel Martinez Alvarez, Michele Chiumenti

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This work explores the benefit of the thermo-metallurgical simulation to tackle the Wire Laser Additive Manufacturing (WLAM) of low-carbon steel components. The Finite Element Analysis is calibrated by process monitoring via thermal imaging and thermocouples measurements, to study the complex thermo-metallurgical behavior inherent to the WLAM process of low carbon steel parts.A critical aspect is the analysis of the heterogeneity in the resulting microstructure. This heterogeneity depends on both the thermal history and the residual stresses experienced during the WLAM process. Because of low carbon grades are highly sensitive to quenching, a high-gradient microstructure often arises due to the layer-by-layer metal deposition in WLAM. The different phases have been identified by scanning electron microscope. A clear influence of the heterogeneities on the final mechanical performance has been established by the subsequent mechanical characterization. The thermo-metallurgical analysis has been used to determine the actual thermal history and the corresponding thermal gradients during the printing process. The correlation between the thermos-mechanical evolution, the printing parameters and scanning sequence has been established. Therefore, an enhanced printing strategy, including optimized process window has been used to minimize the microstructure heterogeneity at ArcelorMittal.

Keywords: additive manufacturing, numerical simulation, metallurgy, steel

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Authors: Thiago Viana

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Eventually train accidents occur on railways and for some specific cases it is necessary to use a train rescue with a crane positioned under a platform wagon. These tumbled machines are collected and sent to the machine shop or scrap yard. In one of these cranes that were being used to rescue a wagon, occurred a fall of hoist due to fracture of two large pins. The two pins were collected and sent for failure analysis. This work investigates the main cause and the secondary causes for the initiation of the fatigue crack. All standard failure analysis procedures were applied, with careful evaluation of the characteristics of the material, fractured surfaces and, mainly, metallographic tests using an optical microscope to compare the geometry of the peaks and valleys of the thread of the pins and their respective seats. By metallographic analysis, it was concluded that the fatigue cracks were started from a notch (stress concentration) in the valley of the threads of the pin applied to the right side of the crane (pin 1). In this, it was verified that the peaks of the threads of the pin seat did not have proper geometry, with sharp edges being present that caused such notches. The visual analysis showed that fracture of the pin on the left side of the crane (pin 2) was brittle type, being a consequence of the fracture of the first one. Recommendations for this and other railway cranes have been made, such as nondestructive testing, stress calculation, design review, quality control and suitability of the mechanical forming process of the seat threads and pin threads.

Keywords: crane, fracture, pin, railway

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Authors: Babatunde Oluwole Ogunsile, Omosola Monisola Fasoranti

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High costs and toxicological hazards associated with the physicochemical methods of producing nanoparticles have limited their widespread use in clinical and biomedical applications. An ethically sound alternative is the utilization of plant bioresources as a low cost and eco–friendly biological approach. Silver nanoparticles (AgNPs) were synthesized from aqueous leaf extract of Tithonia diversifolia plant. The UV-Vis Spectrophotometer was used to monitor the formation of the AgNPs at different time intervals and different ratios of plant extract to the AgNO₃ solution. The biosynthesized AgNPs were characterized by FTIR, X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM). Antimicrobial activities of the AgNPs were investigated against ten human pathogens using agar well diffusion method. The AgNPs yields were modeled using a second-order factorial design. The result showed that the rate of formation of the AgNPs increased with respect to time while the optimum ratio of plant extract to the AgNO₃ solution was 1:1. The hydroxyl group was strongly involved in the bioreduction of the silver salt as indicated by the FTIR spectra. The synthesized AgNPs were crystalline in nature, with a uniformly distributed network of the web-like structure. The factorial model predicted the nanoparticles yields with minimal errors. The nanoparticles were active against all the tested pathogens and thus have great potentials as antimicrobial agents.

Keywords: antimicrobial activities, green synthesis, silver nanoparticles, Tithonia diversifolia

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Authors: Ahmad Shah Farhat

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Background: Prenatal asphyxia or birth asphyxia is the medical situation resulting from a newborn infant that lasts long enough during the birth process to cause physical harm, usually to the brain. Human umbilical cord blood (UCB) is a well-established source of hematopoietic stem/progenitor cells (HSPCs) for allogeneic stem cell transplantation. These can be used clinically to care for children with malignant diseases. Low O2 can cause in proliferation and differentiation of stem cells. Method: the cord blood of 11 infants with 3-5 Apgar scores or need to cardiac pulmonary Resuscitation as an asphyxia group and ten normal infants with more than 8 Apgar scores as the normal group was collected, and after isolating hematopoietic stem cells, the cells were cultured in enriched media for 14 days to compare the numbers of colonies by microscope. Results: There was a significant difference in the number of RBC precursor colonies (red colonies) in cultured media with 107 cord blood hematopoietic stem cells of infants who were exposed to hypoxemia in two wells of palate. There was not a significant difference in the number of white cell colonies in the two groups in the two wells of the plate. Conclusion: Hypoxia in the perinatal period can cause the increase of hematopoietic stem cells of cord blood, special red precursor stem cells in vitro, like an increase of red blood cells in the body when exposed to low oxygen conditions. Thus, it will be usable.

Keywords: asphyxia, neonre, stem cell, red cell

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Authors: Arturs Macanovskis, Vitalijs Lusis, Andrejs Krasnikovs

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Work has three stages. In the first stage was examined pull-out process for steel fiber was embedded into a concrete by one end and was pulled out of concrete under the angle to pulling out force direction. Angle was varied. Length of steel fiber was 26 mm, diameter 0.5 mm. On the obtained force- displacement diagrams were observed jumps. For such mechanical behavior explanation, fiber channel in concrete surface microscopical experimental investigation, using microscope KEYENCE VHX2000, was performed. Surface of fiber channel in concrete matrix after pull-out test (fiber angle to pulling out force direction 70°). At the second stage were obtained diagrams for load- crack opening displacement for breaking homogeneously reinforced and layered fiber concrete prisms (with dimensions 10x10x40 cm) subjected to 4-point bending. After testing was analyzed main crack. On the main crack’s both surfaces were recognized all pulled out fibers their locations, angles to crack surface and lengths of pull-out fibers parts. At the third stage elaborated prediction model for the fiber-concrete beam, failure under bending, using the following data: a) diagrams for fibers pulling out at different angles; b) experimental data about steel-straight fibers locations in the main crack.

Keywords: fiberconcrete, pull-out, fiber channel, layered fiberconcrete

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Authors: D. E. Abulyazied, S. M. Mokhtar, A. M. Motawie

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Polymer blends represent an important class of materials in engineering applications. The incorporation of clay nanofiller may provide new opportunities for this type of materials to enhance their applications. This article reports on the effects of clay on the structure and properties of polymer blends nanocomposites, based on Polyvinyl chloride PVC and styrene co-maleic anhydride SMA blend. Modification of the Egyptian Bentonite EB was carried out using organo-modifier namely; octadecylamine ODA. Before the modification, the cation exchange capacity CEC of the EB was measured. The octadecylamine bentonite ODA-B was characterized using Fourier transform infrared Spectroscopy FTIR, X-Ray Diffraction XRD, and Transition Electron Microscope TEM. A blend of Polyvinyl chloride PVC and styrene co-maleic anhydride SMA (50:50) was prepared in Tetra Hydro Furan (THF). Then nanocomposites of PVC/SMA/ODA-B were prepared by solution intercalation polymerization from 0.50% up to 5% by weight of ODA-B. The nanocomposites are characterized by XRD, TEM. Thermal, nanoindentation, swelling and electrical properties of the nanocomposites were measured. The morphology of the nanocomposites showed that ODA-B achieved good dispersion in the PVC/SMA matrix. Incorporation of 0.5 %, 1%, 3% and 5% by weight nanoclay into the PVC/SMA blends results in an improvement in nanohardness of 16%, 76%, 92%, and 68% respectively. The elastic modulus increased from 4.59 GPa for unreinforced PVC/SMA blend to 6.30 GPa (37% increase) with the introduction of 3% by weight nanoclay. The cross-link density of the nanocomposites increases with increasing the content of ODA-B.

Keywords: PVC, SMA, nanocomposites, nanoindentation, organo-bentonite

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Authors: A. V. Belousov, Yakushenko

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One of the main problems of modern dentistry is development a reliable method to detect inflammation in the gums on the stages of diagnosis and assessment of treatment efficacy. We have proposed a method of gingival fluid intake, which successfully combines accessibility, excluding the impact of the annoying and damaging the gingival sulcus factors and provides reliable results (patent of RF№ 2342956 Method of gingival fluid intake). The objects of the study were students - volunteers of Dentistry Faculty numbering 75 people aged 20-21 years. Cellular composition of gingival fluid was studied using microscope "Olympus CX 31" (Japan) with the calculation of epithelial leukocyte index (ELI). Assessment of gingival micro circulation was performed using the apparatus «LAKK–01» (Lazma, Moscow). Cytological investigation noted the highly informative of epithelial leukocyte index (ELI), which demonstrated changes in the mechanisms of protection gums. The increase of ELI occurs during inhibition mechanisms of phagocytosis and activation of epithelial desquamation. The cytological data correlate with micro circulation indicators obtained by laser Doppler flowmetry. We have identified and confirmed the correlations between parameters laser Doppler flowmetry and data cytology gingival fluid in patients with gingivitis.

Keywords: gingivitis, laser doppler flowmetry, gingival fluid cytology, epithelial leukocyte index (ELI)

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Authors: Syue-Liang Lin, C. Allen Chang

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Luminescence imaging is an important technique used in biomedical research and clinical diagnostic applications in recent years. Concurrently, the development of NIR luminescence probes / imaging contrast agents has helped the understanding of the structural and functional properties of cells and animals. Photodynamic therapy (PDT) is used clinically to treat a wide range of medical conditions, but the therapeutic efficacy of general PDT for deeper tumor was limited by the penetration of excitation source. The tumor targeting biomedical nanomaterials UCNP@PS (upconversion nanoparticle conjugated with photosensitizer) for photodynamic therapy and near-infrared imaging of cancer will be developed in our study. Synthesis and characterization of biomedical nanomaterials were completed in this studies. The spectrum of UCNP was characterized by photoluminescence spectroscopy and the morphology was characterized by Transmission Electron Microscope (TEM). TEM and XRD analyses indicated that these nanoparticles are about 20~50 nm with hexagonal phase. NaYF₄:Ln³⁺ (Ln= Yb, Nd, Er) upconversion nanoparticles (UCNPs) with core / shell structure, synthesized by thermal decomposition method in 300°C, have the ability to emit visible light (upconversion: 540 nm, 660 nm) and near-infrared with longer wavelength (downconversion: NIR: 980 nm, 1525 nm) by absorbing 800 nm NIR laser. The information obtained from these studies would be very useful for applications of these nanomaterials for bio-luminescence imaging and photodynamic therapy of deep tumor tissue in the future.

Keywords: Near Infrared (NIR), lanthanide, core-shell structure, upconversion, theranostics

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Authors: Xufei Liu, Shouxiang Lu, Kim Meow Liew

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Because a relatively small fire could potentially cause damage by smoke corrosion far exceed thermal fire damage, it has been realized that the corrosion of metal exposed to smoke atmospheres is a significant fire hazard, except for toxicity or evacuation considerations. For the burning materials in an actual fire may often be the mixture of combustible matters, a quantitative study on the corrosivity of smoke produced by the combustion of mixture is more conducive to the application of the basic theory to the actual engineering. In this paper, carbon steel samples were exposed to smoke generated by polyvinyl chloride and polypropylene, two common combustibles in industrial plants, with different mixing ratios in high humidity for 120 hours. The separate and combined corrosive effects of smoke were examined subsequently by weight loss measurement, scanning electron microscope, energy dispersive spectroscopy and X-ray diffraction. It was found that, although the corrosivity of smoke from polypropylene was much smaller than that of smoke from polyvinyl chloride, smoke from polypropylene enhanced the major corrosive effect of smoke from polyvinyl chloride to carbon steel. Furthermore, the corrosion kinetics of carbon steel under smoke were found to obey the power function. Possible corrosion mechanisms were also proposed. All the analysis helps to provide basic information for the determination of smoke damage and timely rescue after fire.

Keywords: corrosion kinetics, corrosion mechanism, mixed combustible, SEM/EDS, smoke corrosivity, XRD

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Authors: Mitakshara Sharma, Sonal Sharma

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Vesiculobullous diseases are heterogeneous group of dermatological disorders with protean manifestations. The most important technique for the patients with vesiculobullous diseases is conventional histopathology and confirmatory tests like direct immunofluorescence (DIF) and indirect immunofluorescence (IIF). DIF has been used for decades to investigate pathophysiology and in the diagnosis. It detects molecules such as immunoglobulins and complement components. It is done on the perilesional skin. Diagnosis of DIF test depends on features like primary site of the immune deposits, class of immunoglobulin, number of immune deposits and deposition at other sites. The aim of the study is to correlate DIF with clinical and histopathological findings and to analyze the utility of DIF in the diagnosis of these disorders. It is a retrospective descriptive study conducted for 2 years from 2015 to 2017 in Department of Pathology, GTB Hospital on perilesional punch biopsies of vesiculobullous lesions. Biopsies were sent in Michael’s medium. The specimens were washed, frozen and incubated with fluorescein isothiocyanate (FITC) tagged antihuman antibodies IgA, IgG, IgM, C3 & F and were viewed under fluorescent microscope. Out of 401 skin biopsies submitted for DIF, 285 were vesiculobullous diseases, in which the most common was Pemphigus vulgaris (34%) followed by Bullous pemphigoid (21.5%), Dermatitis herpetiformis (16%), Pemphigus foliaceus (11.9%), Linear IgA disease (11.9%), Epidermolysisbullosa (2.39%) and Pemphigus herpetiformis (1.7%). We will be presenting the DIF findings in the all these vesiculobullous diseases. DIF in conjugation with histopathology gives the best diagnostic yield in these lesions. It also helps in the diagnosis whenever there is a clinical and histopathological overlap.

Keywords: antibodies, direct immunofluorescence, pemphigus, vesiculobullous

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Authors: S. F. Halim, H. F. Naguib, S. N. Lawandy, R. S. Hegazy, M. N. Baheg

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The main drawbacks of the traditional carbon fabric reinforced epoxy resin (CFRP) are low strain failure, delamination between composites layers, and low impact resistance due to the brittleness of epoxy resin. The aim of this study is to enhance the fracture properties of the CFRP composites laminates via the variation of composite's designs. A series of composites were fabricated in which bidirectional (00/900) carbon fabric (CF) layers were laid inside the resin matrix with orientation codes as F1 [(00, 900)/ (00, 900)], F2 [(900, 00)/ (00, 900)] and F3 [(00,900)/ (900, 00). The mechanical and dynamic properties of the composites were estimated. In addition, the morphology of samples surface was examined by scanning electron microscope (SEM) after impact fracture. The results revealed that the CFRP properties could be tailored fitting specific applications by controlling the fabric orientation inside the CFRP composite design. F2 orientation [(900, 00)/ (00.900)] showed the highest tensile and flexural strength values. On the other hand, the impact strength values of composites were in the order F1 > F2 > F3. The storage modulus, loss modulus, and glass transition temperature Tg values obtained from the dynamic mechanical analysis (DMA) examination was in the order F1 > F2 > F3. The variation in the properties of the composite was clearly explained by the SEM micrographs as the failure of F3 orientation properties was referred to as the complete breakage of the CF layers upon fracture.

Keywords: carbon fiber, CFRP, composites, epoxy resins, flexural strength

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Authors: Md. Hafezur Rahaman, Md. Sagor Hosen, Md. Abdul Gafur, Rasel Habib

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This research is a systematic study of effects of poly(D-lactic acid) (PDLA) on the properties of poly(L-lactic acid)(PLLA)/microcrystalline cellulose (MCC)/PDLA blends by stereo complex crystallization. Blends were prepared with constant percentage of (3 percent) MCC and different percentage of PDLA by solution casting methods. These blends were characterized by Fourier Transform Infrared Spectroscopy (FTIR) for the confirmation of blends compatibility, Wide-Angle X-ray Scattering (WAXS) and scanning electron microscope (SEM) for the analysis of morphology, thermo-gravimetric analysis (TGA) and differential thermal analysis (DTA) for thermal properties measurement. FTIR Analysis results confirm no new characteristic absorption peaks appeared in the spectrum instead shifting of peaks due to hydrogen bonding help to have compatibility of blends component. Development of three new peaks from XRD analysis indicates strongly the formation of stereo complex crystallinity in the PLLA structure with the addition of PDLA. TGA and DTG results indicate that PDLA can improve the heat resistivity of the PLLA/MCC blends by increasing its degradation temperature. Comparison of DTA peaks also ensure developed thermal properties. Image of SEM shows the improvement of surface morphology.

Keywords: microcrystalline cellulose, poly(l-lactic acid), stereocomplex crystallization, thermal stability

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Authors: Rui Tu, Yakui Bai, Huailin Li

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The lead-bismuth eutectic (LBE) alloy is a promising candidate of coolant in the fast neutron reactors and accelerator-driven systems (ADS) because of its good properties, such as low melting point, high neutron yields and high thermal conductivity. Although the corrosion of the structure materials caused by the liquid metal (LM) coolant is a challenge to the safe operating of a lead-bismuth eutectic nuclear reactor. Thermodynamic theories, experiential formulas and experimental data can be used for explaining the maintenance of the protective oxide layers on stainless steels under satisfaction oxygen concentration, but the atomic scale insights of such anti-corrosion mechanisms are little known. In the present work, the first-principles calculations are carried out to study the effects of oxygen partial pressure on the formation energies of the liquid metal coolant relevant impurity defects in the anti-corrosion oxide films on the surfaces of the structure materials. These approaches reveal the microscope mechanisms of the corrosion of the structure materials, especially for the influences from the oxygen partial pressure. The results are helpful for identifying a crucial oxygen concentration for corrosion control, which can ensure the systems to be operated safely under certain temperatures.

Keywords: oxygen partial pressure, liquid metal coolant, TDDFT, anti-corrosion layer, formation energy

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Authors: Rongzhou Wang

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Research on designing nano-antibacterial agent with potent and long-lasting antibacterial property is demanding and provoking work. In this study, a core-shell AgBr/cationic polymer nanocomposite (AgBr/NPVP-H10) were synthesized and its structure confirmed by Fourier Transform Infrared Spectrometer (FT-IR), Nuclear Magnetic Resonance (1H NMR) and X-ray diffraction (XRD), and the cationic polymer contents were determined with Thermal Gravimetric Analyzer (TGA). The morphology was directly observed by Transmission Electron Microscope (TEM) which showed that the nanoparticle contains single core and organic shell and had an average diameter of 30.1 nm. The antibacterial test against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli illuminated that this nanocomposite had potent bactericidal activity, which can be attributed to the contact-killing of cationic polymers and releasing-killing of Ag+ ions. In addition, cationic polymer encapsulating AgBr cores gave the resin discs sustained release of Ag+ ions, which may result in long-lasting bactericidal activity. The AgBr/NPVP-H10 nanoparticle with the dual bactericidal capability and long term antimicrobial effect is a promising material aimed at preventing bacterial infection.

Keywords: core-shell nanocomposite, cationic polymer, dual antibacterial capability, long-lasting antibacterial activity

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Authors: Motwkel M. Alhaj, Bashir M. Elhassan

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The East Nile area is located in Khartoum state. The main source of drinking water in the East Nile Area (Sudan) is groundwater. However, fluoride concentration in the water is more than the maximum allowable dose, which is 1.5 mg/l. This study aims to demonstrate and innovative, affordable, and efficient filter to remove fluoride from drinking water. Many researchers have found that aluminum oxide-coated adsorbent is the most affordable technology for fluoride removal. However, adsorption is pH-dependent, and the water pH in the East Nile area is relatively high (around 8), which is hindering the adsorption process. Locally available charcoal was crushed, sieved, and coated with aluminum oxide. Then, different coating configurations were tested in order to produce an adsorbent with a high pH point of zero charge pH PZC in order to overcome the effect of high pH of water. Moreover, different methods were used to characterize the adsorbent, including: Scanning Electron Microscope (SEM), Energy Dispersive X-Ray Spectroscopy (EDX), Brunauer - Emmett - Teller (BET) method, and pH point of zero charge pH PZC. The produced adsorbent has pH PZC of 8.5, which is essential in enhancing the fluoride adsorption process. A pilot household fluoride filter was also designed and installed in a house that has water with 4.34 mg/l F- and pH of 8.4. The filter was operated at a flow rate 250 cm³/min. The total cost of treating one cubic meter was about 0.63$, while the cost for the same water before adsorbent coating modification was 2.33$⁄cm³.

Keywords: water treatment, fluoride, adsorption, charcoal, Sudan

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Authors: Jolanta Jaskowska, Anna Drabczyk, Sonia Kudlacik, Agnieszka Sobczak-Kupiec, Bozena Tyliszczak

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The aim of the study was to select the best conditions for the synthesis of Beetosan's hydrogels with yellow tea. The study determined recipe hydrogel matrix by selecting the appropriate ratio of substrates and to investigate the effect of yellow tea, on the structure and properties of the hydrogel materials. The scope of the research included both to obtain of raw materials required for the synthesis of hydrogel materials, as well as an assessment of their properties. In the first stage of research Beetosan (chitosan derived from bees), and extract the yellow tea China Kekecha was obtained. The second stage was synthesis hydrogels modified by yellow tea. The synthesis of polymeric matrix was preparation under UV radiation. Obtained hydrogel materials were investigated extensively using incubation investigations, absorption capacity, and spectroscopic (FT-IR) and X-ray diffraction (XRD) methods. Moreover, there was also performed the surface wettability test and a photomicrograph of the structure using scanning electron microscope. Analysis of the obtained results confirms that presence of yellow tea does not significantly affect the behavior of the hydrogels in the incubation fluids. The results show that hydrogel materials exhibit compatibility with the incubatory solutions and they also retain the stability in the tested liquids. Hydrogels obtained in this method might be applied in the cosmetics industry and in the field of medicine. This is possible due to the many interesting properties of tea and biocompatibility and non-toxicity hydrogel materials. The authors would like to thank the The National Centre for Research and Development (Grant no: LIDER/033/697/L-5/13/NCBR/2014) for providing financial support to this project.

Keywords: Beetosan, hygrogels, materials, yellow tea

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Authors: M. Benghersallah, L. Boulanouar, G. List, G. Sutter

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The present work is an experimental study on the dry high speed turning of Ti-6Al-4V titanium alloy. The objective of this study is to see for high cutting speeds, how wear occurs on the face of insert and how to evolve cutting forces and chip formation. Cutting speeds tested is 600, 800, 1000 and 1200 m / min in orthogonal turning with a carbide insert tool H13A uncoated on a cylindrical titanium alloy part. Investigation on the wear inserts with 3D scanning microscope revered the crater formation is instantaneous and a chip adhesion (welded chip) causes detachment of carbide particles. In these experiments, the chip shape was systematically investigated at each cutting conditions using optical microscopy. The chips produced were collected and polished to measure the thicknesses t2max and t2min, dch the distance between each segments and ɸseg the inclination angle As described in the introduction part, the shear angle f and the inclination angle of a segment ɸseg are differentiated. The angle ɸseg is actually measured on the collected chips while the shear angle f cannot be. The angle ɸ represents the initial shear similar to the one that describes the formation of a continuous chip in the primary shear zone. Cutting forces increase and stabilize before removing the tool. The chip reaches a very high temperature.

Keywords: dry high speed, orthogonal turning, chip formation, cutting speed, cutting forces

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Authors: Rafiu O. Sanni, Abayomi O. Olajuyigbe, Nelson R. Osungbemiro, Rotimi F. Olaniyan

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The Owena River lies within the drainage basins of the Oni, Siluko, and Ogbesse rivers. The river’s immediate surroundings are covered by dense forests, interspersed by plantations of cocoa, oil palm, kolanut, bananas, and other crops. The objectives were to identify the aquatic plants community, comprising the algae and aquatic macrophytes, observe their population dynamics in relation to the two seasons and identify their economic importance, especially to the neighbouring community. The study sites were determined using a stratified sampling method. Three strata were marked out for sampling namely strata I (upstream)–5 stations, strata II (reservoir) –2 stations, and strata III (outflow) 2 stations. These nine stations were tagged st1, st2, st3…st9. The aquatic macrophytes were collected using standard methods and identified at the University of Ibadan herbarium while the algal samples were collected using standard methods for microalgae. The periphytonic species were scraped from surfaces of rocks (perilithic), sucked with large syringe from mud (epipellic), scraped from suspended logs, washed from roots of aquatic angiosperms (epiphytic), as well as shaken from other particles such as suspended plant parts. Some were collected physically by scooping floating thallus of non-microscopic multicellular forms. The specimens were taken to the laboratory and observed under a microscope with mounted digital camera for photomicrography. Identification was done using Prescott.

Keywords: aquatic plants, aquatic macrophytes, algae, Owena river

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Authors: Siriporn Okonogi, Temsiri Suwan, Sakornrat Khongkhunthian, Jakkapan Sirithunyalug

Abstract:

In this study, silver nanoparticles (AgNPs) were prepared using ascorbic acid as a reducing agent and silver nitrate as a precursor. The effects of gelatin (G) on particle characteristics and dental pathogen inhibition were investigated. The spectra of AgNPs and G-AgNPs were compared using UV-Vis and Energy-dispersive X-ray (EDX) spectroscopy. The obtained AgNPs and G-AgNPs showed the maximum absorption at 410 and 430 nm, respectively, and EDX spectra of both systems confirmed Ag element. Scanning electron microscope showed that AgNPs and G-AgNPs were spherical in shape. Particles size, size distribution, and zeta potential were determined using dynamic light scattering approach. The size of AgNPs and G-AgNPs were 56 ± 2.4 and 67 ± 3.6 nm, respectively with a size distribution of 0.23 ± 0.03 and 0.19 ± 0.02, respectively. AgNPs and G-AgNPs exhibited negative zeta potential of 24.1 ± 2.7 mV and 32.7 ± 1.2 mV, respectively. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the obtained AgNPs and G-AgNPs against three strains of dental pathogenic bacteria; Streptococcus gordonii, Streptococcus mutans, and Staphylococcus aureus were determined using broth dilution method. AgNPs and G-AgNPs showed the strongest inhibition against S. gordonii with the MIC of 0.05 and 0.025 mg/mL, respectively and the MBC of 0.1 and 0.05 mg/mL, respectively. Cytotoxicity test of AgNPs and G-AgNPs on human breast cancer cells using MTT assay indicated that G-AgNPs (0.1 mg/mL) was significantly stronger toxic than AgNPs with the cell inhibition of 91.1 ± 5.4%. G-AgNPs showed significantly less aggregation after storage at room temperature for 90 days than G-AgNPs.

Keywords: antipathogenic activity, ascorbic acid, cytotoxicity, stability

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Authors: Kshanaprava Dhalsamant, Punyadarshini P. Tripathy, Shanker L. Shrivastava

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With present high global population, the need for rising food usage by minimizing food wastage and investment is highly necessary to achieve food security. The purpose of this study is to enlighten the effect of pre-drying treatment on rehydration, color, texture, nanohardness, microstructure and surface morphology of solar dried potato samples dried in the mixed-mode solar dryer. Locally bought potatoes were cleaned and cut into cylindrical pieces and pretreated with sodium metabisulfite (0.5%) for 10 min before placing them in natural convection solar dryer designed and developed in Indian Institute of Technology Kharagpur, India. Advanced quality characteristics were studied using Atomic Force Microscope (AFM), Scanning Electron Microscopy (SEM) and nanoindentation method, along with color, texture and water activity. The rehydration indices of solar dried potatoes were significantly biased by pretreatment followed by rehydration temperature. A lower redness index (a*) with a higher value of yellowness index (b*), chroma (C*) and hue angle (h*) were obtained for pretreated samples. Also, the average nanohardness (H) of untreated samples exhibited substantial lower value (18.46%) compared to pretreated samples. Additionally, a creep displacement of 43.27 nm during 20 s dwell time under constant load of 200

Keywords: pretreatment, nanohardness, microstructure, surface morphology

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Authors: Xiang Wang, Yan Pang, Zhaomiao Liu

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Droplet-based microfluidics have been studied extensively with the development of the Micro-Electro-Mechanical System (MEMS) which bears the advantages of high throughput, high efficiency, low cost and low polydispersity. Droplets, worked as versatile carriers, could provide isolated chambers as the internal dispersed phase is protected from the outside continuous phase. Droplets are used to add reagents to start or end bio-chemical reactions, to generate concentration gradients, to realize hydrate crystallization or protein analyses, while droplets coalescence acts as an important control technology. In this paper, deionized water is used as the dispersed phase, and several kinds of oil are used as the continuous phase to investigate the influence of the viscosity ratio of the two phases on the coalescence process. The microchannels are fabricated by coating a polydimethylsiloxane (PDMS) layer onto another PDMS flat plate after corona treatment. All newly made microchannels are rinsed with the continuous oil phase for hours before experiments to ensure the swelling fully developed. High-speed microscope system is used to document the serial videos with a maximum speed of 2000 frames per second. The critical capillary numbers (Ca*) of droplet pairs in various junctions are studied and compared. Ca* varies with different junctions or different liquids within the range of 0.002 to 0.01. However, droplets without extra control would have the problem of synchronism which reduces the coalescence efficiency.

Keywords: coalescence, concentration, critical capillary number, droplet pair, split

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Authors: Kanokkan Titipornpun, Somphorn Sriarpanon, Apinun Titipornpun, Jan Gimsa, Tripob Bhongsuwan, Noodchanath Kongchouy

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The Phanom and Ko Pha-ngan districts of Surat Thani province are known for their high atmospheric radon concentrations from different sources. While Phanom district is located in an active fault zone, the main radon source in Ko Pha-ngan district is the high amounts of equivalent uranium in the ground surface. Survey measurements of the indoor radon concentrations have been carried out in 105 dwellings and 93 workplaces, using CR-39 detectors that were exposed to indoor radon for forty days. Alpha tracks were made visible by chemical etching and counted manually under an optical microscope. The indoor radon concentrations in the two districts were found to vary between 9 and 63 Bq m-3 (Phanom) and 12 and 645 Bq m-3 (Ko Pha-ngan). The geometric mean radon concentration in Ko Pha-ngan district (51±2 Bq m-3) was significantly higher than in the Phanom district (26±1 Bq m-3) at a significance level of p<0.05 (t-test for independent samples). Nevertheless, only in two dwellings (1%), located in Ko Pha-ngan district, radon concentrations (177 and 645 Bq m-3) were found to exceed the limit recommended by the US EPA of 148 Bq m-3. The two houses are probably located near to radon sources which, in combination with low air convection, led to increased indoor levels of radon. Our study also shows that the geometric mean radon concentration was higher in workplaces than in dwellings (0.05 significance level) in both districts.

Keywords: indoor radon, CR-39 detector, active fault zone, equivalent uranium

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Authors: Maha Al-Ali, Selvakannan Periasamy, Rajarathinam Parthasarathy

Abstract:

Drying temperature is an important factor impacting the physicochemical properties of the dried materials, particularly the pharmaceutical powders. Drying of pharmaceuticals by using microwave radiation is very limited, and the available information about the interaction between the electromagnetic radiations and the pharmaceutical material is still scarce. Therefore, microwave drying process is employed in this work to dry the wet (moisturised) granules of the formulated naproxen-sodium drug. This study aims to investigate the influences of the microwave radiation temperatures on the moisture removal, the crystalline structure, the size and morphology of the dried naproxen-sodium particles, and identify any potential changes in the chemical groups of the drug. In this work, newly formulated naproxen-sodium is prepared and moisturized by wet granulation process and hence dried by using microwave radiation at different temperatures. Moisture analyzer, Fourier-transform infrared spectroscopy, powder X-ray diffraction, and scanning electron microscope are used to characterise the non-moisturised powder (reference powder), the moisturised granules, and the dried particles. The results show that microwave drying of naproxen-sodium at high drying temperature is more efficient than that at low temperatures in terms of the moisture removal. Although there is no significant change in the chemical structure of the dried particles, the particle size, crystallinity and morphology are relatively changed with changing of heating temperature.

Keywords: heating temperature, microwave drying, naproxen-sodium, particle size

Procedia PDF Downloads 138