Wt Fraction Research Articles

Investigation of electrical, electromagnetic interference shielding and tensile properties of 3D-printed acrylonitrile butadiene styrene/carbon nanotube composites

Conductive polymer composites (CPCs) are manufactured by compounding conductive particles with a polymer matrix. There are many applications where they are used, including light-weight applications requiring both electrical and heat conductivity. Carbon nanotubes (CNTs) have been accepted as common materials to accomplish this goal. As part of this research, a material extrusion additive manufacturing (AM) process was utilized to create nanocomposites by a 3D-printing technique. Multi-wall carbon nanotubes (MWCNTs) were mixed in 1, 3 and 6 wt fractions with acrylonitrile butadiene styrene (ABS) and extruded in filament form. Three-dimensionally printed specimens were used to evaluate electrical, electromagnetic interference shielding effectiveness (EMI SE) and tensile properties. The electrical conductivity of the material was 26 times greater than that of ABS. In the X-band of electromagnetic waves, EMI SE's reflected and absorbed portions increased respectively 4 and 16 times. The tensile strength and modulus were enhanced by 15% and 9%, respectively. On composite specimens, microwave heat treatment was applied. There is less void space between the rasters and layers, which helps improve tensile properties. Additionally, 3D-printed specimens were tested for melt flow rate (MFR) and dynamic mechanical behaviour. The nozzle has experienced some wear due to the intrinsic abrasive nature of CNTs.

Graphene assisted enhancement in the cyclic electromechanical properties of polyolefin based multiphasic conducting nano carbon black nanocomposites

Hybrid conducting carbon nanofillers and binary elastomeric-thermoplastic-blend based nanocomposites were synthesized to develop highly flexible matrices for strain sensing applications. The effect of graphene on the strain sensing characteristics of a thermoplastic-elastomeric blend which contains conducting carbon nano black (CCNB) above percolation threshold was investigated. The nanocomposites were crosslinked to different extent by high energy gamma radiation and the effect of elastomeric phase, graphene content and crosslink density on the strain sensing response of the nanocomposites was investigated. With incorporation of ethylene propylene diene monomer (EPDM), elongation at break increased around 2500% and the gauge factor by 200%. The graphene content had a profound effect on the electromechanical response and with the addition of 0.02 wt fraction of graphene around 300% increase in gauge factor was observed. With the increase in graphene content and radiation dose the elastic modulus also increased significantly. The relative change in the resistance with applied strain was reversible for all the nanocomposites and the mechanical hysteresis reduced with the addition of EPDM.

Validation of antioxidant, antiproliferative, and in vitro anti-rheumatoid arthritis activities of epigallo-catechin-rich bioactive fraction from Camellia sinensis var. assamica, Assam variety white tea, and its comparative evaluation with green tea fraction.

The epigallocatechin-rich polyphenolic fraction of Assam variety white tea, traditionally used for the management of diverse inflammatory ailments and health drink, was investigated through eco-friendly green aqueous extraction, TLC, and HPLC characterization, phytochemical screening, in vitro DPPH assay, anti-proteinase, MTT assay on synovial fibroblast and colon cancer cells, apoptotic FACS analysis, cytokine ELISA, p-STAT3 western blotting, and in silico docking analysis. HPLC-TLC standardized white tea fraction (WT-F) rendered higher extractive-yield (21%, w/w), than green tea fraction(GT-F) (12%, w/w). WT-F containing flavonoids and non-hydrolysable polyphenols showed better antioxidant activity, rather than equivalent GT-F. WT-F demonstrated remarkable anti-rheumatoid-arthritis activity via killing of synovial fibroblast cells (66.1%), downregulation of TNF-α (93.33%), IL-6 (87.97%), and p-STAT3 inhibition (77.75%). Furthermore, WT-F demonstrated better anti-proliferative activity against colon cancer cells (HCT-116). Collectively, our study revealed that the white tea fraction has boundless potential as anti-rheumatoid arthritis and anti-proliferative agent coupled with apoptotic, antioxidant anti-proteinase, and anti-inflammatory properties. PRACTICAL APPLICATIONS: Our eco-friendly extracted bioactive aqueous fraction of white tea, characterized by TLC-HPLC study and phytochemical screening have demonstrated remarkable anti-rheumatoid arthritis property and anti-proliferative action on colon cancer cells including potential anti-oxidant, anti-inflammatory, and anti-proteinase efficacy. The test WT-F sample has shown impressive safety on normal mammalian cells. WT-F has demonstrated better efficacy against rheumatoid arthritis and cancer model compared to equivalent green tea fraction. Traditionally, it is extensively used for boosting immunity, and energy, with cosmetic, and agricultural applications by the native inhabitants. So, the aqueous fraction of WT is suggested to be used as a prophylactic nutraceutical supplement and or therapeutic agent in commercial polyherbal formulation to attenuate and management of auto-inflammatory rheumatoid arthritis and carcinogenesis of colon. It is additionally suggested to establish in vivo rheumatoid arthritis animal and clinical study to validate their pharmacokinetic stability and dose optimization coupled with anti-inflammatory, cytotoxicity, and anti-oxidant property.

Temperature-compensated BaV2O6-Ba2V2O7 ceramic composite for ULTCC applications

A temperature-compensated dielectric ceramic composite in the BaV2O6-Ba2V2O7 system has been achieved using rule of mixtures and subsequent modulation of composition based on experiments. The BaV2O6 and Ba2V2O7 powders, synthesized by the solid-state route, are mixed in various compositions and sintered between 525 and 600 °C to produce the composites. The effect of sintering temperature and duration on the density, stability of the phases, microstructure and microwave dielectric properties have been investigated. The BaV2O6 and Ba2V2O7 phases coexist up to 575 °C without any reaction, as established by XRD and SEM-EDS analyses. The composite with 0.60 weight (wt) fraction of BaV2O6 sintered to 96% TD at 550 °C and exhibits a temperature coefficient of resonance frequency (τf) very close to zero (+0.2 ppm/K). The relative permittivity (εr = 10.73), loss tangent (tanδ = 3.66 × 10-4), and quality factor (Qu × f = 30,000 GHz) obtained for this composite are adequate for microwave dielectric applications. This composite shows a linear coefficient of thermal expansion of 14 ppm/K. The excellent chemical compatibility with Al during cofiring, makes this composite a suitable choice for ULTCC application.

Extraction optimization, Total Phenolic-Flavonoids content, HPLC-DAD finger printing, antimicrobial, antioxidant and cytotoxic potentials of Chinese folklore Ephedra intermedia Schrenk & C. A. Mey

Plants from genus Ephedra are commonly used by the Chinese people as folk medicine for treatment of various diseases. The current study was designed to explore the ethno-pharmacological based pharmacological potentials of Ephedra intermedia Schrenk & C.A. Mey. (E. intermedia). Plant aerial parts were extracted using ten solvent systems with increasing order of polarity. Samples were analyzed for total phenolic and flavonoid contents, HPLC-DAD analysis, antibacterial, antifungal, HepG2 cell line cytotoxicity, hemolysis and antioxidant potentials following standard procedures. Highest percent extract recovery was observed in Eth+WT (25.55 % w/w) solvent system. Flavonoid and phenolic contents were higher in chloroform and Met+WT fractions respectively. Considerable antibacterial activity was shown by Eth+Met extract against B. subtilis and K. pneumonia (MIC of 11.1μg/mL for each). Eth extract exhibited high antifungal activity against A. fumigates (15±0.31 mm DIZ). Met+WT extract showed significant cytotoxicity against HepG2 cell lines with IC50 of 13.51+0.69 μg/mL. Substantial free radical scavenging activity (74.9%) was observed for Met+Eth extract. In the current study, several solvent systems were used for more effective extraction of fractions and can be useful in the isolation of phytochemicals. Various fractions exhibited considerable antimicrobial, antioxidant and cytotoxic potentials. Biological potentials of E. intermedia signify its potential uses in microbial, cancer and degenerative disorders and thus warrant further detailed studies.

Use of nanofluids based on carbon nanoparticles to displace oil from the porous medium mode

Understanding the interaction mechanisms between graphene nanoparticles (GNs) and oil molecules is crucial for successful oil recovery. Numerous studies have shown that nanofluids, and in particular nanofluids (NF) from the graphene family (GNF), are suitable candidates for enhanced oil recovery in various reservoirs. Increased oil recovery from nanofluid injection is attributed to changes in wettability, decreases in interfacial tension and changes in viscosity. Therefore, knowing the mechanisms that influence the viscosity of the GNF is an urgent task of modern science, both fundamental and applied. A comprehensive study of the molecular interaction between graphene nanoparticles and hydrocarbon oil molecules was carried out in order to understand the mechanisms that affect the viscosity of nanofluids. The paper presents the results of a study of the rheological properties of oil with different content of graphene nanoparticles in it. At low concentrations of graphene nanoparticles, a 10%-17% decrease in the dynamic viscosity of the base fluid was observed. It is also shown that the relative viscosity is affected not only by the concentration, but also by the temperature. Thus, for the mass fraction of graphene nanoparticles wt = 0.5 × 10-3% and temperature T = 50 °C, a maximum viscosity reduction of 17% is observed. By increasing the concentration of graphene nanoparticles from wt = 5 × 10-3% and more, the oil shows the rheological properties of nanofluid. Based on the data obtained by computer simulation and direct observation of self-assembly of graphene nanoparticles and hydrocarbon molecules of oil, a mechanism has been proposed to explain the reason for the decrease of viscosity of nanofluid at low concentrations of nanoparticles. It was also shown that this nanofluid behavior is mainly possible for hydrocarbon liquids as base fluid and planar graphene nanoparticles.

Analisis dan Optimasi Pengaruh Suhu Gas Umpan Pada Kinerja Acid Gas Removal Unit

The Gas Gathering Station (GGS) in field X processes gas from 16 (sixteen) wells before being sent as selling gas to consumers. The sixteen wells have decreased in good pressure since 2011, thus affecting the performance of the Acid Gas Removal Unit (AGRU). The GGS consists of 4 (four) main units, namely the Manifold Production/ Test, the Separation Unit, the Acid Gas Removal Unit (AGRU), the Dehydration Unit (DHU). The AGRU facility in field X is designed to reduce the acid gas content of CO2 by 21 mol% with a feed gas capacity of 85 MMSCFD. A decrease in reservoir pressure caused an increase in the feed gas temperature and an increase in the water content of the well. Based on the reconstruction of the design conditions into the simulation model, the amine composition consisting of MDEA 0.3618 and MEA 0.088 wt fraction to obtain the percentage of CO2 in the 5% mol sales gas. The increase in feed gas temperature up to 146 F caused foaming due to condensation of heavy hydrocarbon fraction, so it was necessary to modify it by adding a chiller to cool the feed gas to become 60 F. Based on the simulation, the flow rate of gas entering AGRU could reach 83.7 MMSCFD. There was an increase in gas production of 38.1 MMSCFD and condensate of 1,376 BPD. Economically, the addition of a chiller modification project was feasible with the economical parameters of NPV US$ 132,000,000, IRR 348.19%, POT 0.31 year and PV ratio 19.06.

Nrf2 Is a Critical Mediator of CD4 T Cell-Induced Acute Graft-Versus-Host Disease

Recent studies have shown that, in contrast to typical proliferating lymphocytes, alloreactive T (allo-T) cells can be specifically killed by apoptosis through compounds that lead to generation of intracellular reactive oxygen species. Nuclear factor erythroid-derived 2-like 2 (Nrf2) is an ubiquitously expressed transcription factor well-known for its role in regulating the cellular redox pathway, but little is known about its involvement in T-cell biology. In this study, we examined the contribution of Nrf2 to allo-T cells in the context of an allogeneic hematopoietic cell transplant (allo-HCT).To study the role of Nrf2 in T cell function, we first assessed the expression pattern of Nrf2 in activated T cells. We found that total cellular and nuclear Nrf2 expression in T cells were significantly increased 24 hours after in vitro α-CD3/CD28 stimulation (p<0.001), as well as in vivo in donor allo-T cells on day 14 in a well-established MHC-disparate murine allo-HSC model (C57BL/6→BALB/c) (p<0.05) (Fig 1). We next examined the effects of Nrf2 deficiency on T cell alloreactivity by transplanting WT or Nrf2-/- donor T cells in MHC-disparate (C57BL/6→BALB/c), as well as MHC-matched, minor antigen mismatched (C57BL/6→LP) murine models. In both models, allo-HCT recipients of Nrf2-/- donor T cells had significantly less acute graft-versus-host disease (GVHD)-induced mortality (p<0.01), morbidity (p<0.001), and intestinal pathology (p<0.05) (Fig 2a). To test if Nrf2 differentially regulates CD4+ versus CD8+ T cell function, we mixed and matched WT versus Nrf2-/- CD4+ and CD8+ T cells for transplant. Compared to allo-HCT recipients of donor WT CD4+: WT CD8+ T cells, we observed similar GVHD mortality in allo-HCT recipients of donor WT CD4+: Nrf2-/- CD8+ T cells, while we saw reduced GVHD mortality in allo-HCT recipients of donor Nrf2-/- CD4+: WT CD8+ T cells (p<0.01) (Fig 2b). These data support the notion that Nrf2 predominately regulates donor CD4+ and is dispensable for CD8+ T cells during allo-activation and the development of GVHD.We assessed if Nrf2 could affect polarization of donor CD4 T cells after allo-HCT, and found a two-fold increase in the proportion and absolute numbers of CD25+Foxp3+ regulatory T cells (Tregs) in the spleens of donor Nrf2-/- T cell allo-HCT recipients on day 7 post transplant (p<0.001) (Fig 3a). We next examined if Nrf2-deficiency results in greater induction of Tregs (iTregs) or stabilization of natural Tregs (nTregs). While we found an equal fraction of WT and Nrf2-/- naïve CD4+ T cells induced towards Tregs in vitro, we saw a significantly greater percentage of donor Nrf2-/- Tregs expressing Helios, a marker for thymus-derived nTregs, compared to donor WT Tregs in allo-HCT recipients on day 7 (p<0.01) (Fig 3b). Recent studies have suggested that Helios is required to stabilize the expression of FoxP3, and thus, the abundance and inhibitory activity of Tregs in inflammatory settings. In keeping with this notion, we discovered an increase in the cellular FoxP3 protein expression within donor Nrf2-/- Tregs in allo-HCT recipients (p<0.01) (Fig 3c). To further elucidate the biological significance of Nrf2 function on nTregs, we removed CD4+CD25+ putative Tregs from the donor inoculum and transplanted only conventional T cells (Fig 3d). We found that the survival advantage with donor Nrf2-/- T cells was abolished when Tregs were depleted from the donor graft, suggesting that Nrf2 expression in donor T cells negatively regulates nTregs during allo-activation, most likely through downregulation of Helios and FoxP3 expression.Finally, to determine if Nrf2 was critical for T-cell mediated GVT activities, we challenged allo-HCT recipients with A20 (B-cell lymphoma) cells. Using bioluminescent imaging, we found that Nrf2-/- allo-T cells were equally efficient in clearing tumor burdens, and along with their mitigated GVHD activities, resulting in a significantly improved survival outcome.Taken together, we identified a novel role of Nrf2 in CD4+ T cells in the context of allo-HCT. Nrf2 negatively regulated CD4+ nTreg through Helios downregulation during GVHD, but appeared to be dispensable in CD8+ mediated antitumor responses, further highlighting the possibility of separating GVT from GVHD activities. Our findings suggest that targeted manipulation of Nrf2 activities in allo-T cells may offer a useful clinical strategy to mitigate GVHD while preserving GVT responses. [Display omitted] DisclosuresJenq:Seres: Research Funding. van den Brink:PureTech Health: Consultancy; Seres: Research Funding; Jazz Pharmaceuticals: Consultancy; Therakos Institute: Other: Speaking engagement.

Phase equilibria, physical and rheological properties of extracellular polymeric substances in the aqueous urea solutions at different temperatures and concentrations

Extracellular polymeric substances (EPS) were extracted from aerobic granule sludge (AGS) using 8 M aqueous urea solution. It seems that the knowledge of these multi-component systems properties and the ability to predict their phase behavior is necessary for the extraction units design as well as process optimization. In this regard, water activity using the Dynamic Vapor Sorption (DVS) method, viscosity and shear stress, pH, and conductivity were measured at 283.15–343.15 K and 0.0108 to 0.0375 wt fraction of EPS. The salting effects in ternary systems assessed and the results were interpreted in terms of solute-water and solute-solute interactions. It was found these systems were not semi-ideal and except at 283.15 K, had a positive deviation from ideal solution behavior and only at this temperature as the optimum extraction temperature, the salting-in effect was observed for each concentration of EPS. The ternary solutions behave like pseudo-plastic fluids while aqueous urea solution is a Newtonian fluid. Increasing the temperature causes a decrease and increase in pH and conductivity of ternary solutions, respectively and the presence of EPS increases those of 8 M urea solution significantly.

Thermodynamic modeling and new experimental CO2 solubility into aqueous EAE and AEEA blend, heat of absorption, cyclic absorption capacity and desorption study for post-combustion CO2 capture

In the present study, carbon dioxide (CO2) solubility into aqueous blend of 2-(ethylamino) ethanol (EAE) and aminoehtylethanolamine (AEEA) was measured. The performance of CO2 capture by this amine blend was investigated in terms of CO2 solubility, heat of absorption, cyclic CO2 solubility, and initial rate of change of CO2 solubility. CO2 absorption study was carried out using bubble column reactor in the temperature range of 298.15 to 323.15 K, 8.11 to 20.27 kPa CO2 partial pressure, 0.10 to 0.30 wt fraction of AEEA in EAE and AEEA blend, and 10 to 30 wt% total concentration of blend solution. Desorption experiments were performed at 393.15 K. Maximum CO2 solubility was 1.033 mol CO2/mol amine at 298.15 K, 20.27 kPa, 0.30 wt fraction of AEEA in the blend, and 10 wt% of EAE and AEEA solution. A semi-empirical Kent-Eisenberg thermodynamic model and an empirical model were developed to calculate equilibrium CO2 solubility in the studied range of operating conditions with 2.56% and 0.45% average absolute deviation, respectively. At 313.15 K, 15.20 kPa CO2 partial pressure and total concentration of 30 wt% of EAE and AEEA blend, the equilibrium CO2 solubility was resulted as 0.748 mol CO2/mol amine and cyclic solubility of 0.503 mol CO2/mol amine was achieved. Heat of CO2 absorption was measured based on Gibbs Helmholtz equation and found as −72.25 kJ/mol for 30 wt% aqueous EAE and AEEA blend. Results of absorption capacity of EAE and AEEA solution and monoethylethanolamine (MEA) were compared at same operating conditions. This blend had higher CO2 solubility, lesser heat of absorption, more cyclic capacity and faster rate of change of initial CO2 solubility than MEA.

Structural and nuclear shielding qualities of B2O3–PbO–Li2O glass system with different Ag2O substitution ratios

Structural and gamma-ray/neutron radiation protection characteristics of (50-x)B2O3 +40PbO+10Li2O + xAg2O (x = 0, 2.5, 5, 7.5, 10 wt fraction (wt) %) glass system encoded BPLA glasses have been extensively surveyed. The structure of the prepared glasses has been investigated over X-Ray Diffraction (XRD) patterns. With the addition of Ag2O, the glasses' amorphous structures have not deteriorated, and the density and molar volumes of BPLA glasses inversely varied. Mass attenuation coefficients (MAC) for BPLA glasses have been generated enjoying Monte Carlo N-Particle- Extended (MCNPX) simulation code for the broad gamma-ray energy range of 0.015–15 MeV. It has been observed that the MAC values of the BPLA10 glass are higher than the others at all energy levels. Furthermore, while Ag2O concentration in the glass has increased, Half Value Layer (HVLs) Energy Absorption and Exposure Buildup Factors (EABFs, and EBFs) have dropped off for photon energies which are important for shielding applications. It has been noticed from these results that owning higher equivalent atomic number (Zeq) values, BPLA10 can be employed effectively for gamma-ray attenuation. Lastly, the results found for fast neutron removal cross-sections (∑R) have shown that the Ag2O additive grew the density and ∑R values of the glasses. As with photon shielding, it is observed that BPLA10 glass can be more preferable in terms of neutron retention according to other glasses. One can conclude that Ag2O enhances the shielding capacity of the glass system studied and BPLA10 glass can be considered as a good material for gamma-rays/fast neutrons shielding.

Equilibrium CO2 solubility in the aqueous mixture of MAE and AEEA: Experimental study and development of modified thermodynamic model

In the present study, equilibrium solubility of CO2 was studied in the aqueous blend of 2-(methylamino)ethanol (MAE) and aminoethylethanolamine (AEEA). Total concentration of blend solution, weight fraction of AEEA in aqueous (MAE+AEEA) blend, temperature, and partial pressure of CO2 was varied from 10 to 30 wt %, 0.10 to 0.30, 298.15 to 323.15 K, and 8.11 to 20.67 kPa, respectively. Maximum loading 0.944 mol CO2/mol amine was occurred at 298.15 K, 20.27 kPa of CO2 partial pressure, 10 wt % total concentration with 0.30 wt fraction AEEA. The Kent-Eisenberg thermodynamic model was modified by incorporating newly introduced correction factor (Fk) to predict CO2 solubility in the aqueous blend of MAE+AEEA. Experimental data and model predicted data was in good agreement with each other. In addition, heat of CO2 absorption was also calculated for this amine blend and reported as -73.43 kJ/mol.

Interaction and fragility study in salmon gelatin-oligosaccharide composite films at low moisture conditions

Non mammalian gelatin under low moisture conditions could potentially be used in encapsulation technologies in food and pharmaceutical applications. This work explored the interactions between salmon gelatin (SG) and different molecular weight oligosaccharides (at 0.2, 0.4, 0.6 wt fraction) with ∼5% moisture content. SG and glucose, sucrose and maltodextrin were combined to produce visually transparent composites films. Fourier-transformed infrared spectroscopy showed that changes in secondary structure towards a less ordered configuration occurred upon increasing oligosaccharides weight fraction. This interaction was identified as physical in nature and possibly sustained by hydrogen bonding between components. The oligosaccharides also reduced water sorption as indicated by Guggenheim, Anderson and de Boer monolayer parameters derived from dynamic vapour sorption data. This reduction was higher for glucose, possibly due to reduction in free volume in the composite films in the glassy state. Powder X-ray diffraction showed only diffraction peaks associated to the triple helices of the gelatin, which were reduced significantly upon adding glucose and sucrose. Differential scanning calorimetry data showed reductions in Tg and Tm but higher ΔCp values upon increasing oligosaccharides weight fraction, indicating changes in molecular dynamics. Fragility values indicated strong materials; more likely following an Arrhenius-like dependency between the structure relaxation time and temperature. This work provides valuable information about the nature of the interaction between a non-mammalian gelatin and oligosaccharides with different molecular weight. Our findings could be applied for a number of technological applications including encapsulation.

Experimental measurement of carbon dioxide clathrate hydrate in the presence of adamantane and other water soluble and insoluble additives

In this communication, hydrate thermodynamic equilibrium data of adamantane + water + carbon dioxide, 10, 20 and 30 wt fractions of tert-butanol(2-methyl 2-propanol) + water + CO2, 4.5 and 14.5 wt fractions of 2,5-dihydrofuran + water + CO2, 15 and 20 wt fractions of 1,3,5-trioxane + water + CO2, methyl-tert-butyl-ether (MTBE) + water + CO2 and mix of 10 wt% 1,3,5-trioxane and 3.5 wt% 2,5-dihydrofuran + water + CO2 were measured in the pressure range of 1.5–3.5 MPa using isochoric pressure search method. This work took advantage of the Gibbs Phase rule for adamantane and MTBE without considering their weight fraction. The results showed that 1,3,5-trioxane and 2,5-dihydrofuran are good promoters, especially mix of them. 2-methyl 2-propanol acts as an inhibitor in the presence of CO2. Methyl-tert-butyl-ether and adamantane had no impact on CO2 clathrate hydrate.

Study of mechanical and abrasive wear properties of lantana camara particulate reinforced epoxy composite

Abstract Natural fibers have gained researchers’ attention as a replacement to synthetic materials for reinforcing material in polymers such as epoxy due to their advantages such as environment friendliness, biodegradability, renewability and cost effectiveness. Due to such advantages, further exploration of new natural fibers as a filler material in polymer matrix composites for different tribological applications is needed. Lantana camara is one such abundant natural resources whose potential as filler material in polymer composite has not been explored to such a level till date. The present experimental study aims at studying abrasive wear behavior of lantana camara powder reinforced epoxy composites and their mechanical properties such as tensile and flexural strength. Composites having 10, 20 and 30 wt% of lantana camara powder were fabricated using hand layup technique to study the tensile, flexural, impact strength properties along with abrasive wear behavior on a pin on disc wear tester. It was found that both the abrasive wear resistance and strength of the composite samples can be significantly improved by the incorporation of lantana camara particulates into epoxy. At 20 wt fraction of lantana camara both the wear resistance and strength of the composite were found to be optimum. However, further addition of particulate (30%, 40%) results in increase of wear rate as well as lowering of strength. SEM studies were conducted for the wear out samples to study the failure nature at the microscopic level.

Wear studies on carbon fiber nano SiC composites – a Grey-Taguchi method optimization

In the present study, Taguchi method coupled with Grey is used to optimize the process parameter during wear test on carbon fiber nano-SiC composites. The composites are fabricated with various weight (wt) fraction of nano-SiC particle by hand lay method. The mechanical properties such as tensile and compression strength are studied. The microstructure of fabricated composites indicates a uniform dispersion of nano-SiC particles. The wear test was performed using Taguchi L27 Orthogonal Array (OA). The experiments are conducted using various speed, load, and weight fraction of nano-SiC particle for a constant sliding distance of 1500 m. The optimum process parameter was obtained from the Analysis of variance (ANOVA) and Grey relation grade. The experimental results indicate that the dominant parameter was (wt) fraction of nano-SiC particles followed by speed and load. Confirmation test is also performed to validate the experiments. The results indicate that the multi-responses such as wear loss and coefficient of friction are greatly improved through this approach. Finally, the worn surfaces of the composites are examined through Scanning Electron Microscope (SEM).

Application of modified TOPSIS technique in deciding optimal combination for bio-degradable composite

The combined fuzzy analytical hierarchy process (F-AHP) and fuzzy technique for order preference by similarity to ideal solution (F-TOPSIS) approach used to access performance defining attributes (PDAs) such as Tensile Strength, Flexural Strength, Impact Strength, Elongation at break (%), Diffusion Coefficient (D), Sorption Coefficient (S) and Permeability Coefficient (P) of fabricated biodegradable composite materials. The weight of different PDA's was evaluated by F-AHP where the PDA's are Tensile Strength, Flexural Strength Impact Strength, Elongation%, Diffusion, Sorption and Permeability. F-TOPSIS was employed to determine the optimal ranking of the composite materials as BC-1>BC-7>BC-2>BC-6>BC-5>BC-3>BC-4. The alternatives other than neat PCL, with fiber, matrix and graphite at 45, 55 & 15 wt fraction (i.e., BC-7) showed optimum results.

ZnO-B2O3-PbO glasses: Synthesis and radiation shielding characterization

A group of glass samples of chemical formula (10ZnO-(40-x) B2O3-(50 + x) PbO) with x varying from 0 to 40 wt fractions were prepared by solid state reaction method. Amorphous nature of these glasses samples confirmed by X-ray diffraction (XRD) spectra. The density of the prepared samples was measured, and molar volume was calculated. The radiation shielding properties such as mass attenuation coefficient (μ/ρ), half value layer (HVL), tenth value layer (TVL), effective atomic number (Zeff), mean free path (MFP), and buildup factor (BEF) for the prepared glasses were evaluated in the energy range 0.015–15 MeV using XCOM program. Also, the mass attenuation coefficient has been calculated using Monte Carlo simulation (MCNPX code) at six energies (between 0.356 and 1.33 MeV) and the output results have been compared with those collected by XCOM. The MCNPX results match most of the XCOM data very well. The results showed that the mass attenuation coefficient of the prepared glasses is increased with the addition of PbO. ZBP5 glass sample has the highest effective atomic number while ZBP1 sample has the lowest. The radiation shielding properties for the prepared glasses were compared with some commercial window glasses and different types of glass systems.

Sensitivity of compositional measurement of high-pressure fluid mixtures using microcantilever frequency response

Frequency response of an oscillating microcantilever immersed in a fluid mixture can be used to determine the composition of the mixture over a wide range of temperatures and pressures. The Limit of Detection (LOD) in such measurements carried out at high pressures is of great interest for monitoring technologically important processes such as supercritical drying of aerogels. We studied compositional measurement sensitivity of cantilevers defined as the derivative of the cantilever resonant frequency or quality factor with respect to the fluid mixture composition. On the basis of Sader’s model of hydrodynamic interaction of an oscillating immersed cantilever with the surrounding fluid, we derived analytical expressions for the sensitivity that were found to be complex functions of the density and viscosity of the mixture as well as the length, width, thickness, and density of the cantilever. We measured the frequency response of cantilevers immersed in ethanol−CO2 mixtures containing 0 – 0.04 wt fraction of ethanol at 318 K and within the pressure range 10–21 MPa. Using the measured resonant frequency and quality factor together with previously published density and viscosity data for ethanol−CO2 mixtures of various compositions, we calculated the sensitivity at each pressure and temperature and determined the LOD of the measurement. In particular, with our current setup, the LOD ranged from 0.0009 to 0.0071 wt fraction of ethanol in the mixture in the pressure range 10–21 MPa for a 150 μm long cantilever. Our results convincingly illustrate the potential of miniature cantilever-based probes for fast and sensitive in-situ detection of the composition of fluid mixtures in practical technological processes carried out at high pressures.

Influence of spark plasma sintering on microstructure and corrosion behaviour of Ti-6Al-4V alloy reinforced with micron-sized Si3N4 powder

Abstract Ti-6Al-4V-Si3N4 composites were effectively fabricated by spark plasma sintering (SPS) technique. The addition of Si3N4 on Ti-6Al-4V was varied from 5% to 15% (wt fraction). The effect of Si3N4 addition on the densification, microstructure, and microhardness and corrosion behaviour of Ti-6Al-4V was investigated. An increase in microhardness value was recorded from 325.46 HV0.1 to 585.73 HV0.1. X-ray diffraction (XRD) analysis showed that the intensity of diffraction peaks of Si3N4 phase in the composites increased. The sintered Ti-6Al-4V reinforced with Si3N4 compacts revealed the non-existence of intermediate phases, such as TiSi2 (titanium silicide) which was expected. SEM analysis of the spark plasma sintered composites revealed α and β phase microstructures in Ti-6Al-4V with uniform distribution of Si3N4 particulates in the matrix. The corrosion resistance property of the material was improved by the addition of Si3N4 from 0.986629 mm/year to 0.030547 mm/year.