Search results for: confocal fluorescence microscopy

Authors: Wasi Khan, Suboohi Shervani, Swaleha Naseem, Mohd. Shoeb, J. A. Khan, B. R. Singh, A. H. Naqvi

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We have successfully synthesized ZnO/TiO2 nanocomposite using a two-step solochemical synthesis method. The influence of annealing temperature on microstructural, optical, anticandidal, photocatalytic activities and dielectric properties were investigated. X-ray diffraction (XRD) and scanning electron microscopy (SEM) show the formation of nanocomposite and uniform surface morphology of all samples. The UV-Vis spectra indicate decrease in band gap energy with increase in annealing temperature. The anticandidal activity of ZnO/TiO2 nanocomposite was evaluated against MDR C. albicans 077. The in-vitro killing assay revealed that the ZnO/TiO2 nanocomposite efficiently inhibit the growth of the C. albicans 077. The nanocomposite also exhibited the photocatalytic activity for the degradation of methyl orange as a function of time at 465 nm wavelength. The electrical behaviour of composite has been studied over a wide range of frequencies at room temperature using complex impedance spectroscopy. The dielectric constants, dielectric loss and ac conductivity (σac) were studied as the function of frequency, which have been explained by ‘Maxwell Wagner Model’. The data reveals that the dielectric constant and loss (tanδ) exhibit the normal dielectric behavior and decreases with the increase in frequency.

Keywords: ZnO/TiO2 nanocomposites, SEM, photocatalytic activity, dielectric properties

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Authors: Kah Yan How, Peh Fern Ong, Keang Peng Song

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Porphyromonas gingivalis is a black-pigmented, anaerobic Gram-negative bacterium that is important in the progression of chronic and severe periodontitis. This organism has an essential requirement for iron, which is usually obtained from hemin, using specific membrane receptors, proteases, and lipoproteins. In this study, we report the characterization of a novel 24 kDa hemin-binding protein, HmuX, in P. gingivalis W50. The hmuX gene is 651 bp long which encodes for a 217 amino acid protein. HmuX was found to be identical at the C-terminus to the previously reported HmuY protein, differing by an additional 74 amino acids at the N-terminus. Recombinant HmuX demonstrated hemin-binding ability by LDS- PAGE and TMBZ staining. Sequence analysis of HmuX revealed a putative lipoprotein attachment site, suggesting its possible role as a lipoprotein. HmuX was also localized to the outer cell surface by transmission electron microscopy. Northern analysis showed hmuX to be transcribed as a single gene and that hmuX mRNA was tightly regulated by the availability of extra-cellular hemin. P. gingivalis isogenic mutant deficient in hmuX gene exhibited significant growth retardation under hemin-limited conditions. Taken together, these results suggest that HmuX is a hemin-binding lipoprotein, important in hemin utilization for the growth of P. gingivalis.

Keywords: Porphyromonas gingivalis, periodontal diseases, HmuX, protein characterization

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Authors: Elmira Ghanbari, Jan Van Esch, Stephen J. Picken, Sahil Aggarwal

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Organogels are formed by the assembly of low molecular weight gelators (LMWG) into fibrous structures. The assembly of these molecules into crystalline fibrous structures occurs as a result of reversible interactions such as π-stacking, hydrogen-bonding, and van der Waals interactions. Bisamide organogelators with two amide groups have been used as one of LMWGs which show efficient assembly behavior via hydrogen bonding for network formation, the formation of a crystalline network for solvent entrapment. In this study, different bisamide gelators with different lengths of alkyl chains have been added to the bisamide parent gels. The effect of the addition of bisamide additives on the gelation of bisamide gels is described. Investigation of the thermal properties of the gels by differential scanning calorimetry and dropping ball techniques indicated that the bisamide gels can be formed by the addition of a high concentration of the second bisamide components. The microstructure of the gels with different gelator components has been visualized with scanning electron microscopy (SEM) which has shown systematic woven, platelet-like, and a combination of those morphologies for different gels. Examining the addition of a range of bisamide additives with different structural characteristics than the parent bisamide gels has confirmed the effect of the molecular structure on the morphology of the bisamide gels and their final properties.

Keywords: bisamide organogelator additives, gel morphology, gel properties, self-assembly

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Authors: Abhijith N. V., Abhijit Pattnayak, Deepak Kumar

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Nowadays, a group of alloys, namely high entropy alloys (HEA), because of their excellent properties. However, the fabrication of HEAs requires multistage techniques, especially mill-ing, sieving, compaction, sintering, inert media, etc. These processes are laborious, costly, time-oriented, and unsuitable for commercial application. This study adopted a single-stage process-based HVOF thermal spray to develop HEA coating on SS304L substrates. The wear behavior of the deposited HEA coating was explored under different milling time durations (5h, 10h, and 15h, respectively). The effect of feedstock preparation, microstructure, surface chemistry, and mechanical and metallurgical properties on wear resistance was also investigated. The microstructure and composition of both coating and feedstock were evaluated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis. Finally, the phase distribution was correlated by X-ray diffraction (XRD ) analysis. The results showed that 15h milled powder coating indicated better tribological than the base substrate and 5h,10h milled powder coating. A chemically stable Body Centered Cubic (BCC) solid solution phase was generated within the 15h milled powder-coated system, which resulted in superior tribological properties.

Keywords: high entropy alloys coating, wear mechanism, HVOF coating, microstructure

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Authors: M. A. Karakassides, M. Baikousi, A. Kouloumpis, D. Gournis

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Nanocomposites of Carbon Nanorods (CNRs) with Polystyrene (PS), have been synthesized successfully by means of in situ polymerization process and characterized. Firstly, carbon nanorods with graphitic structure were prepared by the standard synthetic procedure of CMK-3 using MCM-41 as template, instead of SBA-15, and sucrose as carbon source. In order to create an organophilic surface on CNRs, two parts of modification were realized: surface chemical oxidation (CNRs-ox) according to the Staudenmaier’s method and the attachment of octadecylamine molecules on the functional groups of CNRs-ox (CNRs-ODA The nanocomposite materials of polystyrene with CNRs-ODA, were prepared by a solution-precipitation method at three nanoadditive to polymer loadings (1, 3 and 5 wt. %). The as derived nanocomposites were studied with a combination of characterization and analytical techniques. Especially, Fourier-transform infrared (FT-IR) and Raman spectroscopies were used for the chemical and structural characterization of the pristine materials and the derived nanocomposites while the morphology of nanocomposites and the dispersion of the carbon nanorods were analyzed by atomic force and scanning electron microscopy techniques. Tensile testing and thermogravimetric analysis (TGA) along with differential scanning calorimetry (DSC) were also used to examine the mechanical properties and thermal stability -glass transition temperature of PS after the incorporation of CNRs-ODA nanorods. The results showed that the thermal and mechanical properties of the PS/ CNRs-ODA nanocomposites gradually improved with increasing of CNRs-ODA loading.

Keywords: nanocomposites, polystyrene, carbon, nanorods

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Authors: Zone-Ching Lin, Hao-Yuan Jheng, Zih-Wun Jhang

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The paper innovatively proposes using the concept of specific down force energy (SDFE) and AFM machine to establish a machining method of cross-shape nanochannel on single-crystal silicon substrate. As for machining a cross-shape nanochannel by AFM machine, the paper develop a method of machining cross-shape nanochannel groove at a fixed down force by using SDFE theory and combining the planned cutting path of cross-shape nanochannel up to 5th machining layer it finally achieves a cross-shape nanochannel at a cutting depth of around 20nm. Since there may be standing burr at the machined cross-shape nanochannel edge, the paper uses a smaller down force to cut the edge of the cross-shape nanochannel in order to lower the height of standing burr and converge the height of standing burr at the edge to below 0.54nm as set by the paper. Finally, the paper conducts experiments of machining cross-shape nanochannel groove on single-crystal silicon by AFM probe, and compares the simulation and experimental results. It is proved that this proposed machining method of cross-shape nanochannel is feasible.

Keywords: atomic force microscopy (AFM), cross-shape nanochannel, silicon substrate, specific down force energy (SDFE)

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Authors: Chaoqun Zhao, Gang Fang

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Twinning is an important deformation mechanism of magnesium alloys, but there is no consensus on the relationship between twinning and ductility. To comprehensively understand the effect of twinning on plastic deformation and cracking, the in situ tensile tests of a magnesium alloy sample along its extrusion direction were conducted, accompanied by the observations using scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD). The misorientation angles around specific axes and trace analysis of grains were used to identify the active twinning systems. The results show that the area fraction of tension twins increases with the increasing strain, resulting in the c-axes of most grains rotating from the normal direction to the transverse direction, and the intensity of (0002) pole is weakened. Based on the analysis of kernel average misorientation (KAM) and SEM maps, it is found that the appearance of tension twins accommodates plastic deformation. However, the stress concentration caused by the intersection of tension twinning with the second phase can lead to crack initiation, and the crack propagates along the direction perpendicular to the tension twinning. For contraction twinning, it plays a role in plastic relaxation and improving strain compatibility during deformation, and is not a necessary potential mechanism of crack nucleation.

Keywords: magnesium alloy, cracking, in-situ EBSD, twinning

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Authors: Patarasuda Chaisupa, R. Clay Wright

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The selection of appropriate biomolecular targets is a crucial aspect of biopharmaceutical development. The Auxin-Inducible Degron Degradation (AID) technology has demonstrated remarkable potential in efficiently and rapidly degrading target proteins, thereby enabling the identification and acquisition of drug targets. The AID system also offers a viable method to deplete specific proteins, particularly in cases where the degradation pathway has not been exploited or when the adaptation of proteins, including the cell environment, occurs to compensate for the mutation or gene knockout. In this study, we have engineered an improved AID system tailored to deplete proteins of interest. This AID construct combines the auxin-responsive E3 ubiquitin ligase binding domain, AFB2, and the substrate degron, IAA17, fused to the target genes. Essential genes of fungi with the lowest percent amino acid similarity to human and plant orthologs, according to the Basic Local Alignment Search Tool (BLAST), were cloned into the AID construct in S. cerevisiae (AID-tagged strains) using a modular yeast cloning toolkit for multipart assembly and direct genetic modification. Each E3 ubiquitin ligase and IAA17 degron was fused to a fluorescence protein, allowing for real-time monitoring of protein levels in response to different auxin doses via cytometry. Our AID system exhibited high sensitivity, with an EC50 value of 0.040 µM (SE = 0.016) for AFB2, enabling the specific promotion of IAA17::target protein degradation. Furthermore, we demonstrate how this improved AID system enhances quantitative functional studies of various proteins in fungi. The advancements made in auxin-inducible protein degradation in this study offer a powerful approach to investigating critical target protein viability in fungi, screening protein targets for drugs, and regulating intracellular protein abundance, thus revolutionizing the study of protein function underlying a diverse range of biological processes.

Keywords: synthetic biology, bioengineering, molecular biology, biotechnology

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Authors: Martin Klaumünzer, Jakob Hübner, Denis Spitzer

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Within this paper, latest results on processing of energetic nanomaterials by means of the Spray Flash Evaporation technique are presented. This technology constitutes a highly effective and continuous way to prepare fascinating materials on the nano- and micro-scale. Within the process, a solution is set under high pressure and sprayed into an evacuated atomization chamber. Subsequent ultrafast evaporation of the solvent leads to an aerosol stream, which is separated by cyclones or filters. No drying gas is required, so the present technique should not be confused with spray dying. Resulting nanothermites, insensitive explosives or propellants and compositions are foreseen to replace toxic (according to REACH) and very sensitive matter in military and civil applications. Diverse examples are given in detail: nano-RDX (n-Cyclotrimethylentrinitramin) and nano-aluminum based systems, mixtures (n-RDX/n-TNT - trinitrotoluene) or even cocrystalline matter like n-CL-20/HMX (Hexanitrohexaazaisowurtzitane/ Cyclotetra-methylentetranitramin). These nanomaterials show reduced sensitivity by trend without losing effectiveness and performance. An analytical study for material characterization was performed by using Atomic Force Microscopy, X-Ray Diffraction, and combined techniques as well as spectroscopic methods. As a matter of course, sensitivity tests regarding electrostatic discharge, impact, and friction are provided.

Keywords: continuous synthesis, energetic material, nanoscale, nanoexplosive, nanothermite

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Authors: Yves Monette, Brad Loewen, Louise Pothier

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This study explores the first bog iron ore extraction activities which took place in colonial New France. Archaeological excavations carried on the founding site of Montreal in the last ten years have revealed the remains of Fort Ville-Marie erected in 1642. In a level related to the fort occupation between 1660 and 1680, kilos of scories, a dozen of half-finished iron artefacts and a light yellow clayey ore material have recovered that point to extractive metallurgy activities at the fort. Examples of scories, artefacts and of a possible bog iron ore were submitted to SEM-EDS analysis. The results clearly indicate that iron was extracted from local limonite ores in a bloomery. We discovered that the gangue material could be traced from the ore to the scories. However, some lime silicates and some accessory minerals found in the scories, like barite and celestine for example, were absent from the ore but present in dolomite fragments found in the same archaeological context. The tracing of accessory minerals suggests that the ironmaster introduced a lime flux in the bloomery charge to maximize the separation of the iron ore. Before the introduction of the blast furnace in Western Europe during the first half of the 18th Century, the use of fluxes in iron bloomery was not a common practice.

Keywords: bog iron ore, extractive metallurgy, French colonial America, Montreal, scanning electron microscopy (SEM)

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Authors: Mardiana Ahamad Zabidi, Akmalluddin Md. Yunus

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Soursop (Anona muricata) is one of the underutilized tropical fruits containing nutrients, particularly dietary fibre and antioxidant properties that are beneficial to human health. This objective of this study is to investigate the feasibility of matured soursop pulp flour (SPF) to be substituted with high-protein wheat flour in bread. Bread formulation was substituted with different levels of SPF (0%, 5%, 10% and 15%). The effect on physicochemical properties and sensory attributes were evaluated. Higher substitution level of SPF resulted in significantly higher (p<0.05) fibre, protein and ash content, while fat and carbohydrate content reduced significantly (p<0.05). FESEM showed that the bread crumb surface of control and 5% SPF appeared to distribute evenly and coalesced by thin gluten film. However, higher SPF substitution level in bread formulation exhibited a deleterious effect by formation of discontinuous gluten network. For texture profile analysis, 5% SPF bread resulted in the lowest value of hardness. The score of sensory evaluation showed that 5% SPF bread received good acceptability and is comparable with control bread.

Keywords: soursop pulp flour, bread, physicochemical properties, sensory attributes, scanning electron microscopy (SEM)

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Authors: J. Oustric, L. Berti, J. Santini

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Nowadays, the objective of durable agriculture, and in particular organic agriculture, is to reduce the level of fertilizer inputs used in crops. Limiting the quantity of fertilizer inputs would optimize the economical result and minimizing the environmental impact. Nutrient deficiency, particularly of a major nutrient (N, P, and K), can seriously affect fruit production and quality. In citrus crops, rootstock/scion combinations. In citrus crop, scion/rootstock combinations are used frequently to improve tolerance to various abiotic stresses. New rootstocks are needed to respond to these constraints, and the use of new tetraploid rootstocks better adapted to lower nutrient intake could offer a promising way forward. The aim of this work was to determine whether a better tolerance to nutrient deficiency could be observed in a doubled diploid seedling and whether this tolerance could be observed in common clementine scion if used as rootstocks. We selected diploid (CM2x) and doubled diploid (CM4x) Citrumelo 4475 seedlings and common clementine (C) grafted onto Citrumelo 4475 diploid (C/CM2x) and doubled diploid (C/CM4x) rootstocks. Nutrient deficiency effects on the seedlings and scion/rootstock combinations were analyzed by studying anatomical, structural and ultrastructural determinants (chlorosis, stomata, ostiole and cells and their organelles), photosynthetic properties (leaf net photosynthetic rate (Pₙₑₜ), stomatal conductance (gₛ), chlorophyll a fluorescence (Fᵥ/Fₘ)) and oxidative marker (malondialdehyde). Nutrient deficiency affected differently foliar tissues, physiological parameters, and oxidative metabolism in leaves of seedlings depending on their ploidy level and of common clementine scion depending on their rootstocks ploidy level. Both CM4x and C/CM4x presented lower foliar damages (chlorosis, chloroplasts, mitochondria, and plastoglobuli), photosynthesis processes alteration (Pₙₑₜ, gₛ, and Fᵥ/Fₘ), and malondialdehyde accumulation than CM2x and C/CM2x after nutrient deficiency. Doubled diploid Citrumelo 4475 can improve nutrient deficiency tolerance, and its use as a rootstock allows to confer this tolerance to the common clementine scion.

Keywords: nutrient deficiency, oxidative stress, photosynthesis, polyploid rootstocks

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Authors: Jaroslaw Mizera, Pawel Wisniewski, Ryszard Sitek

Abstract:

Selective Laser Melting (SLM) is an advanced additive manufacturing technique used for producing parts made of wide range of materials such as: austenitic steel, titanium, nickel etc. In the our experiment we produced a Ti-AlN composite from a mixture of titanium and aluminum nitride respectively 70% at. and 30% at. using SLM technique. In order to define the size of powder particles, laser diffraction tests were performed on HORIBA LA-950 device. The microstructure and chemical composition of the composite was examined by Scanning Electron Microscopy (SEM). The chemical composition in micro areas of the obtained samples was determined by of EDS. The phase composition was analyzed by X-ray phase analysis (XRD). Microhardness Vickers tests were performed using Zwick/Roell microhardness machine under the load of 0.2kG (HV0.2). Hardness measurements were made along the building (xy) and along the plane of the lateral side of the cuboid (xz). The powder used for manufacturing of the samples had a mean particle size of 41μm. It was homogenous with a spherical shape. The specimens were built chiefly from Ti, TiN and AlN. The dendritic microstructure was porous and fine-grained. Some of the aluminum nitride remained unmelted but no porosity was observed in the interface. The formed material was characterized by high hardness exceeding 700 HV0.2 over the entire cross-section.

Keywords: Selective Laser Melting, Composite, SEM, microhardness

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Authors: N. Kaneva, A. Bojinova, K. Papazova

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Thin ZnO films are deposited on glass substrates via sol–gel method and dip-coating. The films are prepared from zinc acetate dehydrate as a starting reagent. After that the as-prepared ZnO sol is aged for different periods (0, 1, 3, 5, 10, 15, and 30 days). Nanocrystalline thin films are deposited from various sols. The effect ZnO sols aging time on the structural and photocatalytic properties of the films is studied. The films surface is studied by Scanning Electron Microscopy. The effect of the aging time of the starting solution is studied inrespect to photocatalytic degradation of Reactive Black 5 (RB5) by UV-vis spectroscopy. The experiments are conducted upon UV-light illumination and in complete darkness. The variation of the absorption spectra shows the degradation of RB5 dissolved in water, as a result of the reaction acurring on the surface of the films, and promoted by UV irradiation. The initial concentrations of dye (5, 10 and 20 ppm) and the effect of the aging time are varied during the experiments. The results show, that the increasing aging time of starting solution with respect to ZnO generally promotes photocatalytic activity. The thin films obtained from ZnO sol, which is aged 30 days have best photocatalytic degradation of the dye (97,22%) in comparison with the freshly prepared ones (65,92%). The samples and photocatalytic experimental results are reproducible. Nevertheless, all films exhibit a substantial activity in both UV light and darkness, which is promising for the development of new ZnO photocatalysts by sol-gel method.

Keywords: ZnO thin films, sol-gel, photocatalysis, aging time

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Authors: Mohammad Nasb, Muhammad Rehan, Chen Hong

Abstract:

Background Meniscus defects critically alter knee function and lead to degenerative changes. Regenerative medicine applications including stem cell transplantation have showed a promising efficacy in finding alternatives to overcome traditional treatment limitations. However, stem cell therapy remains limited due to the substantially reduced viability and inhibitory microenvironment. Since tissue growth and repair are under the control of biochemical and mechanical signals, several approaches have recently been investigated (e.g., low intensity pulsed ultrasound [LIPUS]) to promote the regeneration process. This study employed LIPUS to improve growth and osteogenic differentiation of mesenchymal stem cells derived from human embryonic stem cells to improve the regeneration of meniscus tissue. Methodology: The Mesenchymal stromal cells (MSCs) were transplanted into the epicenter of the injured meniscus in rabbits, which were randomized into two main groups: a treatment group (n=32 New Zealand rabbits) including 4 subgroups of 8 rabbits in each subgroup (LIPUS treatment, MSC treatment, LIPUS with MSC and control), and a second group (n=9) to track implanted cells and their progeny using green fluorescence protein (GFP). GFP consists of the MSC and LIPUS-MSC combination subgroups. Rabbits were then subjected to histological, immunohistochemistry, and MRI assessment. Results: The quantity of the newly regenerated tissue in the combination treatment group that had Ultrasound irradiation after mesenchymal stem cells were better at all end points. Likewise, Tissue quality scores were also greater in knees treated with both approaches compared with controls and single treatment at all end points, achieving significance at twelve and twenty-four weeks [p < 0.05], and [p = 0.008] at twelve weeks. Differentiation into type-I and II collagen-expressing cells were higher in the combination group at up to twenty-four weeks. Conclusions: the combination of mesenchymal stem cells and LIPUS showed greater adhering to the sites of meniscus injury, differentiate into cells resembling meniscal fibrochondrocytes, and improve both quality and quantity of meniscal regeneration.

Keywords: stem cells, regenerative medicine, osteoarthritis, knee

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Authors: F. Z. Benabid, S. Kridi, F. Zouai, D. Benachour

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The aim of present work is to characterize the PVDF/TiO2 blends as nanocomposites, and study the effect of TiO2 on properties of different compositions and the evaluation of the effectiveness of the method used for filler treatment. Nanocomposite samples were synthesized by molten route in an internal mixer. The TiO2 nanoparticles were treated with stearic acid in order to obtain a good dispersion, and the demonstration of the effectiveness of the treatment on the morphology and roughness of the nanofiller was established by microstructural analysis by FTIR and AFM. The various developed nanocomposite compositions were characterized by different methods; i.e. FTIR, XRD, SEM and optical microscopy. Rheological, dielectric and mechanical studies were also performed. The results showed a remarkable increase in the crystallinity of the PVDF/neat TiO2 nanocomposite containing 1 wt% loading of filler, due to the nucleation effect of TiO2 nanoparticles. A good dispersion was obtained in PVDF/treated TiO2 nanocomposites. The rheological study showed an increase in the fluidity in all developed nanocomposite compositions, involved by the orientation of TiO2 nanoparticles in the flow direction. The dielectric study revealed an increase in electrical conductivity in PVDF/neat TiO2 nanocomposites. However, in PVDF/ treated TiO2 nanocomposites, the electrical conductivity was decreased by the addition of 0.5 and 2 wt% loading of filler.

Keywords: nanocomposites, PVDF, TiO2, comixing, mechanical treatment

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Authors: Kwangwon Seo, Haksoo Han

Abstract:

Al-Si was synthesized and introduced in poly 2,2’-m-(phenylene)-5,5’-bibenzimidazole (PBI). As a result, a series of five Al-Si/PBI composite (ASPBI) membranes (0, 3, 6, 9, and 12 wt.%) were developed and characterized for application in high temperature polymer electrolyte membrane fuel cells (HT-PEMFCs). The chemical and morphological structure of ASPBI membranes were analyzed by Fourier transform infrared spectroscopy, X-ray diffractometer and scanning electron microscopy. According to the doping level test and thermogravimetric analysis, as the concentration of Al-Si increased, the doping level increased up to 475%. Moreover, the proton conductivity, current density at 0.6V, and maximum power density of ASPBI membranes increased up to 0.31 Scm-1, 0.320 Acm-2, and 0.370 Wcm-2, respectively, because the increased concentration of Al-Si allows the membranes to hold more PA. Alternatively, as the amount of Al-Si increased, the tensile strength of PA-doped and -undoped membranes decreased. This was resulted by both excess PA and aggregation, which can cause serious degradation of the membrane and induce cracks. Moreover, the PA-doped and -undoped ASPBI12 had the lowest tensile strength. The improved performances of ASPBI membranes imply that ASPBI membranes are possible candidates for HT-PEMFC applications. However, further studies searching to improve the compatibility between PBI matrix and inorganic and optimize the loading of Al-Si should be performed.

Keywords: composite membrane, high temperature polymer electrolyte membrane fuel cell, membrane electrode assembly, polybenzimidazole, polymer electrolyte membrane, proton conductivity

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Authors: Sena Su, Burak Ozbek, Yesim M. Sahin, Sevil Yucel, Dilek Kazan, Faik N. Oktar, Nazmi Ekren, Oguzhan Gunduz

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In recent years, protein, lipid or polysaccharide-based polymers have been used in order to develop biodegradable materials and their chemical nature determines the physical properties of the resulting films. Among these polymers, proteins from different sources have been extensively employed because of their relative abundance, film forming ability, and nutritional qualities. In this study, the biodegradable composite nanofiber films based on fish sarcoplasmic protein (FSP) were prepared via electrospinning technique. Biodegradable polycaprolactone (PCL) was blended with the FSP to obtain hybrid FSP/PCL nanofiber mats with desirable physical properties. Mixture solutions of FSP and PCL were produced at different concentrations and their density, viscosity, electrical conductivity and surface tension were measured. Mechanical properties of electrospun nanofibers were evaluated. Morphology of composite nanofibers was observed using scanning electron microscopy (SEM). Moreover, Fourier transform infrared spectrometer (FTIR) studies were used for analysis chemical composition of composite nanofibers. This study revealed that the FSP based nanofibers have the potential to be used for different applications such as biodegradable packaging, drug delivery, and wound dressing, etc.

Keywords: edible film, electrospinning, fish sarcoplasmic protein, nanofiber

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Authors: Salahaedin Waiezi, Nik Ahmad Nizam Nik Malek, Hassan Abdelmagid Elzamzami, Shahrulnizahana Mohammad Din

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A green and safe approach to the synthesis of silver nanoparticles (AgNP) can be performed using plant leaf extract as the reducing agent. Hence, this paper reports the biosynthesis of AgNP using Clinacanthus nutans plant extract. C. nutans is known as belalai gajah in Malaysia and is widely used as a medicinal herb locally. The biosynthesized AgNP, using C. nutans aqueous extract at pH 10, with the reaction temperature of 70°C and 48 h reaction time, was characterized by UV-Vis spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX), and transmission electron microscope (TEM). A peak appeared in the UV-Vis spectra at around 400 nm, while XRD confirmed the crystal structure of AgNP, with the average size between 20 to 30 nm, as shown in FESEM and TEM. The antibacterial activity of the biosynthesized AgNP, which was performed using the disc diffusion technique (DDT) indicated effective inhibition against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. In contrast, minimal antibacterial activity was detected against Enterococcus faecalis and methicillin-resistant Staphylococcus aureus (MRSA). In general, AgNP produced using C. nutans leaf extract possesses potential antibacterial activity.

Keywords: silver nanoparticles, Clinacanthus nutans, antibacterial agent, biosynthesis

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Authors: Mehmet Fahri Sarac, Gokcen Akgun

Abstract:

Ti–6Al–4V alloys are widely used in biomedical industries because of its attractive mechanical and physicochemical properties. However, they have poor wear resistance. High velocity oxygen fuel (HVOF) coatings were investigated as a way to improve the wear resistance of this alloy. In this paper, different mass ratio of Al₂O₃-TiO₂ powders (60/40, 87/13 and 97/3) was employed to enhance the tribological properties of Ti–6Al–4V. The tribological behavior was investigated by wear tests using ball-on-disc and pin-on-disc tribometer. The microstructures of the contact surfaces were determined by a scanning electron microscopy before and after the test to study the wear mechanism. Uncoated and coated surfaces after wear test are also subjected to micro-hardness tests. The tribological test results showed that the microhardness, friction and wear resistance of coated Ti-6Al-4V alloys increases by increasing TiO₂ content in the powder composite when other experimental conditions were constant. Finally, Al₂O₃-TiO₂ powder composites for the investigated conditions, both coating samples had satisfactory values of friction and wear resistance, and they could be suitable candidates for Ti–6Al–4V material.

Keywords: HVOF (High Velocity Oxygen Fuel), Al₂O₃-TiO₂, Ti-6Al-4V, tribology

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Authors: Tahir Ahmad, M. Kamran, R. Ahmad, M. T. Z. Butt

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Hybrid aluminum metal matrix composites with 1, 2, 3 and 4 wt. % of silica sand nanoparticles and electro-less nickel coated carbon fibers were successfully developed using sand casting technique. Epoxy coating of carbon fibers was removed and phosphorous-nickel coating was successfully applied via electro-less route. The developed hybrid composites were characterized using micro hardness tester, tensile testing, and optical microscopy. The gradual increase of reinforcing phases yielded improved mechanical properties such as hardness and tensile strength. The increase in hardness was attributed to the presence of silica sand nanoparticles whereas electro-less nickel coated carbon fibers enhanced the tensile properties of developed hybrid composites. The microstructure of the developed hybrid composites revealed the homogeneous distribution of both carbon fibers and silica sand nanoparticles in aluminum based hybrid composites. The formation of dendrite microstructure is the main cause of improving mechanical properties.

Keywords: aluminum based hybrid composites, mechanical properties, microstructure, microstructure and mechanical properties relationship

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Authors: Joy Marie Mora, Mark Daniel De Luna, Tsair-Wang Chung

Abstract:

Transesterification reaction of soybean oil with methanol was carried out to produce fatty acid methyl esters (FAME) using calcined alkali metal (Na and Li) supported by pumice silica as the solid base catalyst. Pumice silica catalyst was activated by loading alkali metal ions to its surface via an ion-exchange method. Response surface methodology (RSM) in combination with Box-Behnken design (BBD) was used to optimize the operating parameters in biodiesel production, namely: reaction temperature, methanol to oil molar ratio, reaction time, and catalyst concentration. Using the optimized sets of parameters, FAME yields using sodium and lithium silicate catalysts were 98.80% and 98.77%, respectively. A pseudo-first order kinetic equation was applied to evaluate the kinetic parameters of the reaction. The prepared catalysts were characterized by several techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) sorptometer, and scanning electron microscopy (SEM). In addition, the reusability of the catalysts was successfully tested in two subsequent cycles.

Keywords: alkali metal, biodiesel, Box-Behnken design, heterogeneous catalyst, kinetics, optimization, pumice, transesterification

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Authors: Aminreza Noghrehabadi, Mohammad Behbahani, Ali Pourabbasi

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In this experimental work, unlike conventional methods that mix two nanoparticles together, silver nanoparticles have been synthesized on the surface of graphene. In this research, the effect of adding modified graphene nanocomposite-silver nanoparticles to the base fluid (distilled water) was studied. Different transmission electron microscopy (TEM) and field emission scanning electron microscope (FESEM) techniques have been used to examine the surfaces and atomic structure of nanoparticles. An ultrasonic device has been used to disperse the nanocomposite in distilled water. Also, the thermal conductivity coefficient was measured by the transient hot wire method using the KD2-pro device. In addition, the thermal conductivity coefficient was measured in the temperature range of 30°C to 50°C, concentration of 10 ppm to 1000 ppm, and ultrasonic time of 2 minutes to 15 minutes. The results showed that with the increase of all three parameters of temperature, concentration and ultrasonic time, the percentage of increase in thermal conductivity will go up until reaching the optimal point, and after passing the optimal point, the percentage of increase in thermal conductivity will have a downward trend. To calculate the thermal conductivity of this nanofluid, a very accurate experimental equation has been obtained using Design Expert software.

Keywords: thermal conductivity, nanofluids, enhancement, silver nano particle, optimal point

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Authors: Hamid Merzouk, Djahida Touati-Talantikite, Amina Zaabar

Abstract:

New nanosized materials are in huge expansion worldwide. They play a fundamental role in various industrial applications thanks their unique and functional properties. Moreover, in recent years, a great effort has been made to the design and control fabrication of nanostructured semiconductors such zinc sulphide. In recent years, much attention has been accorded in doped and co-doped ZnS to improve the ZnS films quality. We present in this work the preparation and characterization of ZnS and Al doped ZnS thin films. Nanoparticles ZnS and Al doped ZnS films are prepared by chemical bath deposition method (CBD), for various dopant concentrations. Thin films are deposed onto commercial microscope glass slides substrates. Thiourea is used as sulfide ion source, zinc acetate as zinc ion source and manganese acetate as manganese ion source in alkaline bath at 90 °C. X-ray diffraction (XRD) analyses are carried out at room temperature on films and powders with a powder diffractometer, using CuKα radiation. The average grain size obtained from the Debye–Scherrer’s formula is around 10 nm. Films morphology is examined by scanning electron microscopy. IR spectra of representative sample are recorded with the FTIR between 400 and 4000 cm-1.The transmittance (70 %) is performed with the UV–VIS spectrometer in the wavelength range 200–800 nm. This value is enhanced by Al doping.

Keywords: ZnS, nanostructured semiconductors, thin films, chemical bath deposition

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Authors: G. Amariei, K. Boltes, R. Rosal, P. Leton

Abstract:

Wastewater treatment plants (WWTPs) are supposed to hold an important place in the reduction of emerging contaminants, but provide an environment that has potential for the development and/or spread of adaptation, as bacteria are continuously mixed with contaminants at sub-inhibitory concentrations. Reviewing the literature, there are little data available regarding the use of adapted bacteria forming activated sludge community for toxicity assessment, and only individual validations have been performed. Therefore, the aim of this work was to study the toxicity of Triclosan (TCS) and Ibuprofen (IBU), individually and in binary combination, on adapted activated sludge (AS). For this purpose a battery of biomarkers were assessed, involving oxidative stress and cytotoxicity responses: glutation-S-transferase (GST), catalase (CAT) and viable cells with FDA. In addition, we compared the toxic effects on adapted bacteria with unadapted bacteria, from a previous research. Adapted AS comes from three continuous-flow AS laboratory systems; two systems received IBU and TCS, individually; while the other received the binary combination, for 14 days. After adaptation, each bacterial culture condition was exposure to IBU, TCS and the combination, at 12 h. The concentration of IBU and TCS ranged 0.5-4mg/L and 0.012-0.1 mg/L, respectively. Batch toxicity experiments were performed using Oxygraph system (Hansatech), for determining the activity of CAT enzyme based on the quantification of oxygen production rate. Fluorimetric technique was applied as well, using a Fluoroskan Ascent Fl (Thermo) for determining the activity of GST enzyme, using monochlorobimane-GSH as substrate, and to the estimation of viable cell of the sludge, by fluorescence staining using Fluorescein Diacetate (FDA). For IBU adapted sludge, CAT activity it was increased at low concentration of IBU, TCS and mixture. However, increasing the concentration the behavior was different: while IBU tends to stabilize the CAT activity, TCS and the mixture decreased this one. GST activity was significantly increased by TCS and mixture. For IBU, no variations it was observed. For TCS adapted sludge, no significant variations on CAT activity it was observed. GST activity it was significant decreased for all contaminants. For mixture adapted sludge the behaviour of CAT activity it was similar to IBU adapted sludge. GST activity it was decreased at all concentration of IBU. While the presence of TCS and mixture, respectively, increased the GST activity. These findings were consistent with the viability cells evaluation, which clearly showed a variation of sludge viability. Our results suggest that, compared with unadapted bacteria, the adapted bacteria conditions plays a relevant role in the toxicity behaviour towards activated sludge communities.

Keywords: adapted sludge community, mixture, PPCPs, toxicity

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Authors: Mukesh Saran, Ashima Bagaria

Abstract:

Green nanotechnology is the most researched field in the current scenario. Herein we study the synthesis of Zinc and Ferrous nanoparticles using Moringa oleifera leaf extracts. Our protocol using established protocols heat treatment of plant extracts along with the solution of copper sulphate in the ratio of 1:1. The leaf extracts of Moringa oleifera were prepared in deionized water. Copper sulfate solution (1mM) was added to this, and the change in color of the solution was observed indicating the formation of Cu nanoparticles. The as biosynthesized Cu nanoparticles were characterized with the help of Scanning Electron Microscopy (SEM), and Fourier Transforms Infrared Spectroscopy (FTIR). It was observed that the leaf extracts of Moringa oleifera can reduce copper ions into copper nanoparticles within 8 to 10 min of reaction time. The method thus can be used for rapid and eco-friendly biosynthesis of stable copper nanoparticles. Further, we checked their antimicrobial and antioxidant potential, and it was observed that maximum antioxidant activity was observed for the particles prepared using the heating method. The maximum antibacterial activity was observed in Streptomyces grisveus particles and in Triochoderma Reesei for the maximum antifungal activity. At present, we are engaged in studying the anti-inflammatory activities of these as prepared nanoparticles.

Keywords: green synthesis, antibacterial, antioxidant, antifungal, anti-inflammatory

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Authors: Maged Syed Ahamd, Manal Mohamed Yasser, Essam Sholkamy

Abstract:

In this paper, we reported that selenium (Se) nanoparticles were firstly biosynthesized with a simple and eco-friendly biological method. Their shape, size, FTIR (Fourier Transform Infrared spectroscopy), UV–vis spectra, TEM (Transmission Electron Microscopy) images and EDS (Energy Dispersive Spectroscopy) pattern have been analyzed. TEM analyses of the samples obtained at different stages indicated that the formation of these Se nanostructures was governed by an incubation time (12- 24- 48 hours). The Se nanoparticles were initially generated and then would transform into crystal seeds for the subsequent growth of nanowires; however obtaining stable Se nanowire with a diameter of about 15-100 nm. EDS shows that Se nanoparticles are entirely pure. The IR spectra showed the peaks at 550 cm-1, 1635 cm-1, 1994 cm-1 and 3430 cm-1 correspond to the presence of Se-O bending and stretching vibrations. The concentrations of Se-NPs (0, 1, 2, 5 µg/ml) did not give significantly effect on both two cell lines while the highest concentrations (10- 100 µg/ml gave significantly effects on them. The lethal dose (ID50%) of Se-NPs on Hep2 G and MCF-7 cells was obtained at 75.96 and 61.86 µg/ml, respectively. Results showed that Se nanoparticles as anticancer agent against MCF-7 cells were more effective than Hep2 G cells. Our results suggest that Se-NPs may be a candidate for further evaluation as a chemotherapeutic agent for breast and liver cancers.

Keywords: selenium nanoparticle, Streptomyces bikiniensis, nanowires, chemotherapeutic agent

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Authors: Hoda Aleali, Nastran Mansour, Maryam Mirzaie

Abstract:

In this paper, we study the optical nonlinearities of Silver sulfide (Ag2S) nanostructures dispersed in the Dimethyl sulfoxide (DMSO) under exposure to 532 nm, 15 nanosecond (ns) pulsed laser irradiation. Ultraviolet–visible absorption spectrometry (UV-Vis), X-ray diffraction (XRD), and transmission electron microscopy (TEM) are used to characterize the obtained nanocrystal samples. The band gap energy of colloid is determined by analyzing the UV–Vis absorption spectra of the Ag2S NPs using the band theory of semiconductors. Z-scan technique is used to characterize the optical nonlinear properties of the Ag2S nanoparticles (NPs). Large enhancement of two photon absorption effect is observed with increase in concentration of the Ag2S nanoparticles using open Z-scan measurements in the ns laser regime. The values of the nonlinear absorption coefficients are determined based on the local nonlinear responses including two photon absorption. The observed aperture dependence of the Ag2S NP limiting performance indicates that the nonlinear scattering plays an important role in the limiting action of the sample.The concentration dependence of the optical liming is also investigated. Our results demonstrate that the optical limiting threshold decreases with increasing the silver sulfide NPs in DMSO.

Keywords: nanoscale materials, silver sulfide nanoparticles, nonlinear absorption, nonlinear scattering, optical limiting

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Authors: Kathleen Moyer, Nora Ait Boucherbil, Murtaza Zohair, Janna Eaves-Rathert, Cary Pint

Abstract:

This study demonstrates the significance of interface engineering in the field of structural energy by being the first case where the performance of the system with the structural battery is greater than the performance of the same system with a battery separate from the system. The benefits of improving the interface in the structural battery were tested by creating carbon fiber composite batteries (and independent graphite electrodes and lithium iron phosphate electrodes) with and without an improved interface. Mechanical data on the structural batteries were collected using tensile tests and electrochemical data was collected using scanning electron microscopy equipment. The full-cell lithium-ion structural batteries had capacity retention of over 80% exceeding 100 cycles with an average energy density of 52 W h kg−1 and a maximum energy density of 58 W h kg−1. Most scientific developments in the field of structural energy have been done with supercapacitors. Most scientific developments with structural batteries have been done where batteries are simply incorporated into the structural element. That method has limited advantages and can create mechanical disadvantages. This study aims to show that a large improvement in structure energy research can be made by improving the interface between the structural device and the battery.

Keywords: composite materials, electrochemical performance, mechanical properties, polymer interface, structural batteries

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Authors: K. F. Md Yunos, N. S. Pajar, N. S. Azmi

Abstract:

Oily wastewater in Malaysian refinery has become a big issue of water and environment pollution to be solved urgently. The results of an experimental study on separation of oily wastewaters are presented. The characteristic of filtration behavior of commercial polymer ultrafiltration (UF) membranes was evaluated in the treatment of oily wastewater from palm oil refinery. The performance of different molecular weight cut off 5kDa and 10kDa regenerated cellulose membrane were evaluated and compared and the fouling behavior were analyzed by scanning electron microscopy (SEM). The effect of pressure (0.5, 1.0, 1.5, 2.0, 2.5 bar) and sample concentration (100%, 75%, 50%, 25%) on fouling of 5kDa and 10kDa membrane were evaluated. The characteristic of the sample solutions were analyzed for turbidity, total dissolved solid (TDS), total suspended solid (TSS), BOD, and COD. The results showed that the best fit to experimental data corresponds to the cake layer formation followed by the intermediate blocking for the experimental conditions tested. A more detailed analysis of the fouling mechanisms was studied by dividing the filtration curves into different regions corresponding to the different fouling mechanisms. Intermediate blocking and cake layer formation or combinations of them were found to occur during the UF experiments depending on the operating conditions.

Keywords: fouling, oily wastewater, regenerated cellulose, ultrafiltration

Procedia PDF Downloads 414