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Studies on Lightweight Geopolymer Concrete
Get PDFThe studies on Lightweight Geopolymer concrete (LGC) are leading-edge in the development of sustainable and eco-friendly concrete. Attempts were being made to develop LGC by various methods of production. This paper reviews about previously published research work on lightweight geopolymer concrete and the observations to the material binders - an alternate to the Ordinary Portland Cement (OPC) by the utilization of industrial by-products, alkaline activator solution, foaming agents, chemical expansive agents, lightweight aggregate, production methods, and their physical and mechanical properties. The main focus is to investigate pore size formation, density, compressive strength and curing conditions. From the review it is found that the stabilization of foam and the control of efflorescence are the two challenging problems faced by the industry for the mass production of lightweight geopolymer foam concrete. Furthermore, topics for future work in this field were suggested
Chemical studies of chromanone-thiadiazole, pyridazine and thiosulfin hybrid
Get PDF3-Chlorochromanon derivatives 4a,b are reacted with hydrazine hydrate to afford 3-hydrazino-2-tetrahydro(pyran or thiopyran)chroman-4-ones 5a,b. Then compound 5a,b is reacted with carbon disulfide and acetylacetone to give 5'-thiolo - 2-tetrahydro(pyrane or thiopyran)- spiro[chroman-3,2'- [1,3,4]-thiadiazole]-4-one 6a,b and 3', 5'-dimethyl- 2-tetrahydro(pyran or thiopyran) spiro [chroman-3,2'- piprazine]-4-one 7a,b, respectively. α-Chlorosulfenyl chlorides 2a,b are treated with thioacetic acid to form α-chloroalkyl disulfides 8a,b, the latter compounds 8a,b were treated with morpholine to furnish a mixture of 1,3,4-oxadithiins 9a,b, 1,3,4,5,6-oxatetrathiocins 10a,b, 1,2,4-trithiolanes 11a,b (cis- and trans-), 1,2,4,5-tetrathiins (cis- and trans-) 12a,b. The formation of the new compounds are confirmed by spectral (IR, 1H NMR, and MS) analysis
Composition-Dependent Dielectric and Piezoelectric Properties of Na1-zKzNbO3 Ceramics
Get PDFSodium potassium niobate, Na1-zKzNbO3, is a ceramic material that exhibits dielectric and piezoelectric properties, which can be tuned by changing the composition of the material. The dielectric properties of Na1-zKzNbO3 ceramics are characterized by a high dielectric constant and low loss, which makes them useful for applications in capacitors, filters, and resonators. Pellets of Na1-zKzNbO3 (0.120 ≤ z ≤ 0.210) were prepared by the solid-state reaction technique. The structural and morphological study was carried out on the prepared compositions at room temperature (RT). A Piezoelectric indirect constant (d33*) was obtained for the prepared compositions. Additionally, dielectric measurements were performed at frequencies 10-1000 kHz, from ambient temperature to 500 °C. For the prepared compositions with z = 0.175, a break in the XRD peak shifting patterns was observed, and the average grain size was calculated at 2.044 ± 0.3 µm. Also, the maximum indirect piezoelectric constant (d33*) was observed for z = 0.175 among the prepared compositions. For the prepared compositions, compositions with z = 0.140 showed the highest dielectric constant (peak value 1486, 385 °C). Among the prepared samples, dielectric constant (ε), loss tangent (tan δ) and electric conductivity (σ) were found to be minimum for the composition with z = 0.175 at all the measured frequencies. Anomalous dielectric, piezoelectric and structural properties are evident for the samples with z = 0.175 among the prepared samples. Overall, the composition-dependent dielectric and piezoelectric properties of Na1-zKzNbO3 ceramics make them promising materials for use in various electronic and sensing applications where high-performance dielectric and piezoelectric materials are required
Investigation of Laurus Tamala leaves extract as an environmentally acceptable corrosion inhibitor for soft steel in 1M HCl: Electrochemical, DFT, and surface characterization techniques
Get PDFLaurus Tamala leaves extract (LTLE) has been employed as a soft steel corrosion inhibitor in a 1M Hydrochloric acid media. Chemical (weight loss) and electrochemical investigations were carried out to assess the corrosion rate and percentage inhibition efficiency of the extract. The electrochemical polarization results have demonstrated that plant leaves extract functions as a mixed type inhibitor. The stability of the inhibitor is tested at elevated temperatures by weight loss method. The corrosion inhibition mechanism is interpreted through adsorption mechanism, and the LTLE components has obeyed the Langmuir adsorption isotherm for soft steel. The interaction of the components of the extract is assessed through FT-IR technique. The surface morphology, roughness and hydrophobicity in presence and absence of the extract have been characterized through SEM, AFM and water contact angle techniques respectively. The highest inhibitory efficiency is 96.21% for 24 h as recorded by weight loss method. Additionally, the DFT computations has revealed the inhibitor’s adsorption through electron donor-acceptor interactions
Polyacrylonitrile and polylactic acid blend nanofibre spinning using needleless electrospinning technique
Get PDFIn this work, polyacrylonitrile (PAN) and polylactic acid (PLA) blended polymers have been used to prepare a flexible and partially biodegradable electrospun nanofibre sheet suitable for filtration application. Also, acetone has been used as a replacement of dimethyl formamide (DMF) during spinning and a needleless (wire electrode) electrospinning machine has been used for filament preparation. Initially, PAN fibre is spun with DMF and various parameters, such as polymer concentration, voltage, distance between electrodes and RH%, are standardised. With these standard parameters, PLA is then added with PAN, and PLA concentration is optimised without affecting the desired fibre diameter. Further, the amount of acetone with DMF is also standardised without affecting the fibre diameter. Finally, polymer concentration of 2.5% PAN with 0.5% of PLA, a potential difference of 55 kV, electrode distance of 125mm at 35% RH and 10% acetone are found suitable for getting the desired nanofibre with minimum diameter.
Low-stress mechanical properties of sericin-coated polyester fabric for sportswear application
Get PDFPolyester fabric has been treated with sericin using different methods to improve the comfort of sportswear. Five different coating methods have been investigated, namely polyester fabric treated with alkali, alkali and sericin, sericin with DMDHEU and glutaraldehyde mixture, plasma followed by sericin and glutaraldehyde, and plasma followed by sericin and DMDHEU. The low-stress mechanical properties of the samples have been investigated. Sericin-treated fabric samples show higher tensile resilience, shear rigidity, shear hysteresis, bending and bending hysteresis, compressional energy and compressional resilience and lower extensibility, surface friction and surface roughness. The hand values of all the samples have improved, and the raw fabric treated with plasma, sericin, and DMDHEU has produced the highest overall hand value of the samples
Indian system of medicine used concurrently with standard conventional medicine improves quality of life in patients of cardio vascular diseases (C.V.D)
Get PDFWorldwide there is increased shift towards usage of traditional medicine in patients of chronic diseases like Cardio Vascular Disorders. In India, these medicines are used concurrently. Objective of the study was to ascertain prevalence and effect of concurrent traditional drug therapy with standard pharmacotherapy in patients with CVD. The present study used a cross sectional study design to assess the prevalence and a prospective cohort design to assess the effect of concurrent Ayurvedic medicines with standard pharmacotherapy in terms of quality of life. After screening 600 patients, 128 were found taking such medicines. Out of these, 100 were recruited as cases (Group-I), while 100 who were matched in terms of age, body mass index, ejection fraction, and receiving standard therapy only were recruited as controls (Group-II). Assessment parameters included demographic, biochemical, ejection fraction through echocardiography, distance covered in six Minute walk Test (6MWT), Quality of Life (QOL) through Kansas City Cardio-myopathy Questionnaire (KCCQ) and Seattle Angina Questionnaire (SAQ) with follow up at 6 months. Prakriti as mentioned in Ayurveda was also assessed using a questionnaire. Both groups were comparable at base line. Total 87 in Group-I and 91 in Group-II completed the study. Further, 76% patients were diagnosed with heart failure (HF) and 24% with coronary artery disease (CAD). There was no change in distance covered in 6MWT in both HF or CAD groups. But there was improvement in all cases in domains of KCCQ and SAQ as compared to controls. To conclude, concurrent use of traditional medicine with standard conventional care in CVD may improve quality of life in cardiovascular disorders.
Organobentonite as an efficient and reusable adsorbent for cationic dyes removal from aqueous solution
No full textIn the present study, cetyltrimethylammonium bromide (CTAB) was used to modify raw bentonite (Ben) through the replacement of exchangeable cations to form CTAB modified bentonite (CTAB-Ben). Both Ben and CTAB-Ben were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and Brunauer-Emmet-Teller (BET) analysis. Adsorption potential of Ben and CTAB-Ben were explored for the removal of two cationic dyes i.e. Rhodamine B (RB) and Crystal violet (CV) from aqueous solutions. The maximum dye adsorption capacity of CTAB-Ben was found to be 93.15 and 14.76 mg g-1 for CV and RB, respectively. The adsorption data of both the adsorbents was better explained by Freundlich isotherm whereas the pseudo second order (PSO) model better fitted the kinetics data. Regeneration studies revealed that CTAB-Ben could be reused upto five adsorption-desorption cycles
Ethnonutritional, ethnomedicinal and sacred religious rites of “Karkidaka charya” a traditional seasonal practice of Kerala
Get PDFKarkidaka charya is the seasonal regimen followed during Karkidaka, the last month of the Malayalam calendar (mid-July to mid-August). It is the month with torrential rain, low digestive fire and causing the vitiation of three humours (Vata, Pitta and Kapha) according to Ayurveda classics. Economic imbalances of the early farming communities, low immunity and environment which is favourable for epidemics, made the month of Karkidaka more vulnerable. Hence, our older generation followed a strict regimen to avert from this detrimental Karkidaka. The present study is a compilation of the traditional practices in Kerala during the month of Karkidaka and its critical analysis. About 22 unique practices were observed in different parts of Kerala during this month. Most of the practices were observed as a caution for upcoming pandemic in the severe rainy month. The practices cover ethnonutritional, ethnomedicinal and sacred religious aspects of Karkidaka charya.
The effect of Nigella sativa on serum levels of insulin-like growth factor and its binding proteins in postmenopausal women with low bone density: A triple-blind randomized controlled trial
Get PDFAnimal studies have shown that Nigella sativa (NS) seed oil can increase Insulin-like growth factor (IGF-1) serum levels. This study aimed to investigate the effect of oral capsule NS on serum levels of IGF-1 and its binding proteins (IGFBP-1, IGFBP-3) in postmenopausal women with bone loss density. Sixty postmenopausal women of 50 to 65 years with bone loss density randomly received a soft capsule of NS oil 1000 mg or placebo once daily for six months with a 1:1 allocation ratio. DEXA method was used to measure bone density. Serum concentrations of IGF-1, IGFBP-1 and-3, ALT, AST, ALP, Cr, and urea were measured at baseline and after the intervention. There were no significant differences in serum levels of IGF-1, IGFBP-1, urea, Cr, ALT, AST, and ALP between the two groups at the end of six months. However, a significant increase has been shown in IGFBP-3 between groups after the intervention (Adjusted mean difference: 95% CI: 1.65: 0.36 to 2.97; p=0.013). We observed a significant increase in IGFBP-3 serum levels without any side effects. Additional research with an increased number of participants may be needed for further clarification of its beneficial anabolic effects on the GH system.