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Influence of geopolymer aggregates on micro-structural and durability characteristics of OPC concrete
Get PDFThis paper explores the physical, mechanical and durability characteristics of Fly ash—ground granulated blast furnace slag (GGBS) based Geopolymer aggregates include Specific gravity, impact value, crushing value, loss angles abrasion value, attrition value and water absorption respectively. Besides, scanning electron microscopy (SEM) was done to diagnose the microstructure of geopolymer aggregates. In addition to this mechanical, durability and microstructural behavior of the ordinary portland cement concrete made with the geopolymer aggregate includes compressive strength, split tensile strength, open porosity, water absorption, sorpitivity, Rapid Chloride Penetration Test (RCPT) and SEM with EDS were investigated. With help of SEM interfacial transition zone (ITZ) was examined. In this paper, three types of geopolymer aggregates are prepared by replacing 0, 10, and 20% of fly ash with GGBS cured under oven (at 60° for 12 h) and ambient conditions. The study considers the two grades of concrete M20 and M40 as per IS 456-2000. However, concrete prepared geopolymer Aggregates (80% fly ash and 20% GGBS) Showed higher resistance among all the tests and giving similar results at ambient and oven curing
A Numerical Approach to Estimate First Ply Failure of Fibre Metal Laminate
Get PDFFibre Metal Laminates (FMLs) are laminates consisting of metal layers and fibre reinforced composite layers. These laminates are designed to improve some specific properties of constituent metals and composites layers. Estimation of First Ply Failure (FPF) Loads of these FMLs is a part in the broad characterization of these materials. A numerical method is developed for the estimation of FPF when these laminates are used as simply supported plates subjected to uniformly distributed load. Various failure criterions are used to identify these loads. The proposed method has been validated with the results of exact (Navier) solution available in the literature. FPFs are estimated for different groups of FMLs based on Aluminum, Titanium and Magnesium layers. The results are presented in the form of non-dimensional FPF and deformation values for various aspect ratios
Modeling and optimization of dead metal zone to reduce cutting forces in micro milling of hardened AISI D2 steel,
No full textImproving machining performance with reduced power consumption is a big challenge for the manufacturer to reduce production cost. Since the dead metal zone (DMZ) directly afects the cutting forces, the present study aims to optimize the
DMZ to reduce the cutting and thrust forces in the micro-milling of hardened AISI D2 steel using teaching–learning-based
optimization technique (TLBO). Finite element model for DMZ geometry and mechanistic models for cutting and thrust
forces are developed, integrated and estimated the cutting and thrust forces. The estimated forces are compared with experimental results and a good agreement found between them. In the next stage, process parameters (cutting speed and feed per tooth) and tool parameters (nose radius and rake angle) are optimized using TLBO technique to minimize DMZ geometry
keeping the surface roughness (≤2 µm), tool wear (≤30 µm) and amplitude of cutter vibration (≤30 µm) as constraints. The
optimal working condition is as follows: a spindle speed of 2225 rpm, a feed per tooth of 5.0 µm, and a nose radius of 7.6 µm
and rake angle of 3.0°. Under the optimal working condition, side length of DMZ and DMZ angle is found as 13.8 mm and
5.74°, respectively, and the cutting and thrust forces are estimated as 3.27 and 2.37 N, respectively. These cutting and thrust forces are about 21.3–65.7 and 34.8–55.3%, respectively, less than the experimental results
AnOptimizationStrategytoImprovePerformanceinElectrochemical Discharge Machining of Borosilicate Glass Using Graph Theory Algorithm and Desirability Index
No full textElectrochemical discharge machining (ECDM) a combined version of electrical discharge machining (EDM) and electrochemical machining (ECM), is an emerging alternative method to shape low machinability material like borosilicate glass. Since the material removal rate (MRR) decreases with the machining depth due to insufficient electrolyte at the tool tip, the radial over cut (ROC) is found at the entrance due to accumulation of electrolyte. To overcome these issues, a hybrid electrolyte (HE) of NaOH+ 5% KOH is proposed in the present study, because the HE has low viscosity and high electrical conductivity compared to individual conventional electrolyte (CE). Experiments are conducted with an in-hose developed ECDM set-up integrated with metal oxide semiconductor field effect transistor (MOSFET) assisted power module. Experimental plan developed based on L9 orthogonal array with three process variables, electrolyte concentration, applied voltage, and duty factor at three levels, taper angle (TA) and ROC considered as quality characteristics and MRR is considered as performance characteristics. In this paper, a novel simultaneous multi-response optimization technique by combining Graph theory algorithm (GTA) and desirability function approach (DFA) is presented. Weights for the responses are calculated using the GTA and are used to evaluate overall (composite) desirability index (ODI) and it is treated as the multi response performance index (MRPI) to determine optimum levels for the process variables. ANOVA test indicated that DF has more influence on machining performance with 47.16% for CE and 57.06% for hybrid electrolyte. An increased MRR, and a reduction in OC and TA was noticed with HE compared to CE. In addition, SEM images revealed a smooth machined surface texture with CE and a feathery-like machined surface texture with HE. The average of the response values from the confirmation tests were found to be within the ±5% of predicted mean value, and the optimal values obtained from the proposed optimisation technique are confirme
A Review on Fabrication of Thermoset Prepreg Composites using Out-of-Autoclave Technology
No full textAutoclave is the technology that has been extensively used to manufacture high-grade performance composite parts for aerospace applications. This technology has been limited to aerospace industries only, primarily due to its high cost in manufacturing parts. The researchers then considered
an alternative approach “Out-of-autoclave” (OOA) process, aiming at cost and time optimization. Nonautoclave methods such as OOA cure processes have been developed lately. The OOA process has a high potential for a drastic cost reduction in the manufacturing of composite aerospace structures. It
processes parts that have a quality similar to that of parts cured using the autoclave technology. Specially designed OOA prepregs are available in the market for OOA processing, some of which are certified for aerospace manufacturing. This review paper briefly focuses on OOA prepregs and OOA processes that are used for aerospace components manufacturing. Future areas of development in the aerospace sector based on cost optimization and faster cycle times are also discussed in this paper
Insilico drug repurposing using FDA approved drugs against Membrane protein of SARS-CoV-2
No full textIn the present study, biosorption of lead using green algae as biosorbent from aqueous solution was studied with one-factor-
at-a-time (OFAT) method. The batch biosorption process is a function of agitation time, biomass loading, initial concentration
of lead and solution pH. Further, face-centered central composite design under RSM application was applied to optimize the process parameters to get more percentage biosorption of lead. The percentage removal of lead was found to be 71% in batch experiment by OFAT method, whereas in RSM study the maximum biosorption rate 75% was reached at optimum conditions of agitation time 40 min., dosage 3 g, initial ion concentration 15 mg/L and pH 3.35. The adsorbent was char-acterized by FTIR, scanning electron microscopy (SEM) and Brunauer–Emmett Teller (BET) analysis. The kinetic models
were also analyzed to determine the biosorption mechanism. It was found that the data best followed to pseudo second order
mechanism. Biosorption isotherms were successfully ftted by Langmuir isotherm (R2=0.974) and d) Freundlich isotherm
(R2=0.983) models
Overexpression of RNA ‐binding bacterial chaperones in rice leads to stay‐green phenotype, improved yield and tolerance to salt and drought stresses
No full textAbstract
Genes encoding bacterial cold shock proteins A ( CspA , 213 bp) and B ( CspB , 216 bp) were isolated from Escherichia coli strain K12, which showed 100% homology with gene sequences isolated from other bacterial species. In silico domain, analysis showed eukaryotic conserved cold shock domain (CSD) and ribonuclease‐binding domain (RBD) indicating that they bind to RNA and are involved in temperature stress tolerance. Overexpression of these two genes in E. coli resulted in higher growth in presence of 200 mM NaCl and 300 mM mannitol. Western blot confirmed the translational products of the two genes. Seedlings of indica rice were transformed with Agrobacterium tumefaciens containing pCAMBIA1301 CspA and CspB genes. Transgene integration was confirmed by β‐glucuronidase (GUS) histochemical assay, polymerase chain reaction (PCR) amplification, and gene copy number by Southern blotting. Chlorophyll, proline, Na + , and K + contents were higher in transgenics exposed to 150 mM NaCl and drought (imposed by withholding water) stresses during floral initiation stage. Catalase (CAT), superoxide dismutase (SOD), and guaiacol peroxidase (GPX) activities increased, while malondialdehyde (MDA) content was low in transgenics. Transgenics displayed increased root, shoot, and panicle lengths, root dry mass, and a distinct stay‐green (SGR) phenotype. Higher transcript levels of CspA , CspB , SGR , chlorophyllase , isopentenyl adenine transferase 1 ( IPT1 ), 9‐ cis ‐epoxycarotenoid dioxygenase ( NCED ), SOD , and sirtuin 1 ( SIRT1 ) genes were observed in transgenics compared to wild type plants (WT) under multiple stresses. Present work indicates that bacterial chaperone proteins are capable of imparting SGR phenotype, salt and drought stress tolerance alongside grain improvement
Assessment of lead biosorption performance of spent Gelidiella acerosa (marine macro algae): Optimization, isotherm, kinetic, and column studies
No full textIn this research, biosorption of Lead using spent Gelidiella acerosa from synthetic aqueous phase was studied in batch and fixed bed modes. Biosorbent was prepared from waste biomass of Gelidiella acerosa after extraction of agar as a model industrial waste recycle. The process efficiency and optimum lead uptake were evaluated by considering initial pH, lead concentration, and biosorbent dosage as process variables and contact time and temperature as fixed parameters. Central composite design of Response Surface Methodology was used to optimize process parameters and ANOVA showed that initial pH of lead solution significantly influences the biosorption. Interaction effects of different process parameters on process efficiency were analyzed with the help of surface response plots. The highest lead biosorption of 90.75% was noticed at optimum conditions of pH 5.15, initial lead concentration 27.35 mg L −1 and biosorbent dosage 0.04 g. Various kinetic equations were used to analyze the biosorption mechanism and found that metal binding is due to chemical reaction with multi stage mass transfer. Langmuir isotherm was found to be well fitted to equilibrium data. Column studies were also conducted to assess the suitability of the process to continuous operations. The most popular Thomas and Yoon nelson models were used to evaluate the fitness of column studies. Biosorbent was characterized using FTIR and SEM to determine surface functional groups and surface texture
Pila virens as sentinel of silica nanoparticles toxicity induced oxidative stress
No full textBiodiesel is an eco-friendly, renewable, and potential liquid biofuel mitigating greenhouse gas emissions. Biodiesel has been produced initially from vegetable oils, non-edible oils, and waste oils. However, these feedstocks have several disadvantages such as requirement of land and labor and remain expensive. Similarly, in reference to waste oils, the feedstock content is succinct in supply and unable to meet the demand.
Recent studies demonstrated utilization of lignocellulosic substrates for biodiesel production using oleaginous microorganisms. These microbes accumulate higher lipid
content under stress conditions, whose lipid composition is similar to vegetable oils. In this paper, feedstocks used for biodiesel production such as vegetable oils, non-edible oils, oleaginous microalgae, fungi, yeast, and bacteria have been illustrated. Thereafter, steps enumerated in biodiesel production from lignocellulosic substrates through pretreatment, saccharification and oleaginous microbe-mediated fermentation, lipid extraction, transesterification, and purification of biodiesel are discussed. Besides, the importance of metabolic engineering in ensuring biofuels and biorefinery and a brief note on integration of liquid biofuels have been included that have significant importance in terms of circular economy aspects
Design, Synthesis and Cytotoxic Activity of 1,2,4-Thiadiazole Linked 1,3,4-Thiadiazole-Carbazole Derivatives
Get PDFWe have designed and synthesized a series of novel amide derivatives of 1,3,4-oxadiazole-isoxazolpyridine-benzimidazole (10a-j), and their structures are characterized by 1HNMR,
13CNMR and mass spectral data. The preliminary anticancer applications of these compounds are screened towards four
types of human cancer cell lines including PC3 (prostate), A549 (lung), MCF-7 (breast) and DU-145 (prostate). The assay results revealed that many of the target compounds displayed remarkable anticancer activity. Among them, the compounds 10f, 10g, 10h and 10j are found to be more potent than
rest of the compounds. In particularly, one compound 10f displayed most promising anticancer activity