Numerical Investigation into Web Crippling of Cold-Formed Lipped Z-sections under Two-Flange Loadings

R. Dwivedi,A. Y. Vyavahare 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.3

This paper aims to evaluate the web crippling capacities of cold-formed Z-sections under two-flange load cases defined in the AISI Specification. The design specification provides an empirical equation to determine the web crippling strength. However, the results from this equation for different loading and support conditions are not consistent as it predicts unconservative for certain cases and over-conservative for some other cases. In this study, web crippling capacities of Z-sections are determined using validated finite element models and compared with the AISI Specification. The comparison showed that the empirical equation predicts adequate strength for fastened support conditions and conservative strength for unfastened support conditions under End-Two-Flange (ETF) load case. For the Interior-Two-Flange (ITF) load case, the empirical equation predicts unconservative strength for fastened support conditions and over-conservative strength for unfastened support conditions. Therefore, a detailed numerical study is carried out to recommend new web crippling coefficients using a parametric study under both loading cases for fastened and unfastened support conditions. The parametric study is based on 540 finite element models. Based on the results of this study new web crippling design equations are proposed for both load cases and support conditions using the direct strength method.

International patenting activity in the field of carbon nanotubes

R.K Gupta,I. Dwivedy 한국물리학회 2005 Current Applied Physics Vol.5 No.2

Carbon nanotubes (CNT) are unique nanostructures with remarkable electronic and mechanical properties and could be used, for example, in nanometre-sized electronics or to strengthen polymer materials. Today, both SWNT and MWNT are being used as key components in the production of high-strength composites, and advanced sensors, electronic and optical devices, catalysts, batteries and fuel cells. Patenting activity in this sub-field of nanotechnology registered a spurt during the last 12 years..implying a breakthrough bringing about a technological paradigm shift in the field of fullerene since carbon nanotubes are fullerene-related structures. CNT is, thus, one of the key technologies likely to revolutionize information technology, materials and medicine and the present study aim to examine technological developments in this field based on international patenting activity during the period of 1991.2003.

Zinc, Copper and Cobalt Concentrations in Blood During Inflammation of the Mammary Gland in Dairy Cows

Naresh, R.,Dwivedi, S.K.,Dey, S.,Swarup, D. Asian Australasian Association of Animal Productio 2001 Animal Bioscience Vol.14 No.4

A study was undertaken to record the utilization of some micro-elements during inflammation of the mammary gland. Two groups of twenty five animals each suffering from subclinical and clinical mastitis were selected for the study. All the animals were maintained on identical diets. Blood zinc level in cows with subclinical mastitis ($5.66{\pm}0.52$) was significantly (p<0.05) lower than that of healthy cows ($8.46{\pm}1.10ppm$). No significant difference was, however, recorded in blood copper and cobalt levels between healthy and mastitic cows.

Optical Analysis of Zinc Oxide Quantum Dots with Bovine Serum Albumin and Bovine Hemoglobin

Wahab, R.,Dwivedi, S.,Khan, M. S.,Al-Senaidy, A. M.,Shin, H. S.,Musarrat, J.,Al-Khedhairy, A. A. Springer Science + Business Media 2014 Journal of pharmaceutical innovation Vol.9 No.1

Quantum dots (QDs) are widely used in medical, industrial, and household applications owing to their excellent biological property. For its wide medical application, the biocompatibility of QDs is an important aspect of research. The aim of the present study was to synthesize zinc oxide quantum dots (ZnO-QDs) and to investigate the interaction with bovine serum albumin (BSA) and bovine hemoglobin (BHb) using fluorescence quenching method and circular dichroism (CD). The study suggests that the electrostatic force of attraction favors the adsorption of BSA onto ZnO-QDs. The fluorescence quenching of BSA and BHb using QD indicates the formation of QDs-BSA complexes. The CD spectra also showed the changes in secondary structure of proteins by interacting with QDs.

Chemopreventive Effects of Pomegranate Seed Oil on Skin Tumor Development in CD1 Mice

Chandradhar Dwivedi,Justin J. Hora,Emily R. Maydew,Ephraim P. Lansky 한국식품영양과학회 2003 Journal of medicinal food Vol.6 No.3

Pomegranate seed oil was investigated for possible skin cancer chemopreventive efficacy in mice. In the mainexperiment, two groups consisting each of 30, 4 5-week-old, female CD 1 mice were used. Both groups had skin cancer ini-tiated with an initial topical exposure of 7,12-dimethylbenzanthracene and with biweekly promotion using 12-O-tetrade-canoylphorbol 13-acetate (TPA). The experimental group was pretreated with 5% pomegranate seed oil prior to each TPA ap-plication. Tumor incidence, the number of mice containg at least one tumor, was 100% and 93%, and multiplicity, theaverage number of tumors per mouse, was 20.8 and 16.3 per mouse after 20 weeks of promotion in the control and pome-granate seed oil-treated groups, respectively (P, .05). In a second experiment, two groups each consisting of three CD 1 micewere used to assess the effect of pomegranate seed oil on TPA-stimulated ornithine decarboxylase (ODC) activity, an im-portant event in skin cancer promotion. Each group received a single topical application of TPA, with the experimental groupreceiving a topical treatment 1 h prior with 5% pomegranate seed oil. The mice were killed 5 h later, and ODC activity wasassessed by radiometric method. The experimental group showed a 17% reduction in ODC activity. Pomegrante seed oil (5%)significantly decreased (P, .05) tumor incidence, multiplicity, and TPA-induced ODC activity. Overall, the results highlightthe potential of pomegranate seed oil as a safe and effective chemopreventive agent against skin cancer.

Antioxidant Defense and Lipid Peroxide Level in Liver and Kidneys of Lead Exposed Rats

Patra, R.C.,Swarup, D.,Dwivedi, S.K. Asian Australasian Association of Animal Productio 2000 Animal Bioscience Vol.13 No.10

An experiment was carried out with 48 IVRI 2CQ rats 6-8 week old, weighing 50-100 g, to study the effect of lead exposure on antioxidant defense, lipid peroxide level, status of thiol groups and concentration of lead in the liver and kidneys at the end of the exposure and also after withdrawal of lead administration. Twenty four rats were given lead at a daily dose rate of 1 mg lead/2 ml of distilled water/kg body weight as lead acetate solution intraperitoneally for a period of 30 days. Another 24 control rats received 2 ml of sterile normal saline solution (0.85% NaCl)/kg body weight in an identical manner. A many-fold increase in concentration of lead was associated with a non-significant (p>0.05) decrease in the activities of superoxide dismutase (SOD) in the liver (27%) and kidneys (12%) and catalase in kidneys (22%). A significant (p<0.05) increase in lipid peroxide level was recorded in the liver (40%) compared with control values. There were significant (p<0.05) decreases in the total thiol and protein bound thiol contents in liver and an increase in non-protein bound thiol groups in the kidneys of lead exposed rats. During the 10 day observation period after withdrawal of lead administration, no significant change was observed with respect to any of the above parameters indicating that a 10 day withdrawal period was not enough for restoration of normality. It is concluded that the magnitude of response and the resultant changes in the lipid peroxide concentration, and the activities of SOD and catalase were not identical in the liver and kidneys of lead-exposed rats.

Evaluation of Ascorbic Acid Treatment in Clinical and Subclinical Mastitis of Indian Dairy Cows

Naresh, Ram,Dwivedi, S.K.,Swarup, D.,Patra, R.C. Asian Australasian Association of Animal Productio 2002 Animal Bioscience Vol.15 No.6

A study was carried out to assess the therapeutic effect of ascorbic acid in mastitis of dairy cows. The herd with a population of 250-275 lactating cows was screened for clinical and subclinical mastitis for a period of 5 months. Based on inclusion and exclusion criteria, eighteen animals each with clinical and subclinical mastitis in one quarter only were selected as study population. Twelve cows (group A) with normal udder and health were also selected as a healthy control. Clinical mastitis cows were grouped as B (n=12) and C (n=6). Cows of group B were treated with ascorbic acid at 25 mg/kg, subcutaneously for 5 consecutive days and intramammary infusion (Ampicillin sodium 75 mg and Cloxacillin sodium 200 mg/infusion) based on antibiotic sensitivity test, till complete recovery. Group C cows received only intramammary infusion till the complete recovery. Eighteen subclinical mastitis cows were divided in group D (n=12) and E (n=6). Cows of group D were treated with ascorbic acid at 25 mg/kg subcutaneously for 5 consecutive days while group E did not receive any treatment. California mastitis test (CMT), somatic cell count (SCC), physical changes of udder and milk were used to diagnose and classify the mastitis. Evaluation of the therapy was based on CMT score and physical changes of udder and milk. Sample size calculation was also performed but was not followed for control groups due to scarcity of cases. Adequate blinding was done when and where required to avoid the biases. Confounding variables like herd, age of the cow, stage of the lactation, season and geographical region were duly considered and adequate blocking was followed. Ascorbic acid was administered in clinical and subclinical cases even after cure considering its immunostimulatory and healing inducing effects. The recovery rate was faster in cases of clinical mastitis treated with ascorbic acid along with an intramammary infusion (group B) than the quarters of group C cows. Quarter wise the average duration/number (3.16${\pm}$0.11 days) of antimicrobial intramammary infusion was significantly (p<0.01) less in group B than that of average duration/number (5.33${\pm}$0.20 days) of group C. Subclinical mastitis cows treated with ascorbic acid showed 83.33% recovery while 16.77% did not respond to treatment till last day of study. Cows of group E (untreated) did not recovered from the mastitis. Subjective parameters viz. swelling, pain reflex of udder and physical changes in milk from quarter of ascorbic acid treated cows (group B) disappeared earlier than that of group C cows. It is concluded from this study that the ascorbic acid might be useful as an adjunct in case of clinical mastitis to get quick recovery with less number of intramammary infusions. High recovery rate in subclinical mastitis quarters of group D cows is appreciable and opens a new avenue to conduct further trials in a larger population in various field conditions. However, the pharmacology of ascorbic acid with particular reference to health of mammary gland needs to be investigated.

Investigation on the Effect of Asymmetric Cyclic Loading on Ratcheting Deformation and Bulk Texture Development in HSLA Steel

Pushpendra Kumar Dwivedi,R. Vinjamuri,S. K. Sahoo,Krishna Dutta 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.8

Ratcheting deformation in association with bulk texture evolution in HSLA steel is studied in this investigation. The cyclicdeformation behaviors and damage modes of the specimens are obtained at room temperature, employing asymmetric stresscontrolledtests under various combinations of mean stress and stress amplitudes. Bulk texture measurements of the specimensare done adopting an X-ray diffraction analysis. The results exhibit an increase in strain accumulation from 0.23 to 30.61%associated with a sharp reduction in ratcheting life from 3320 to 880 cycles by the increment in mean stress/stress amplitude. A continuous cyclic softening until the final failure is observed for all the ratcheting tests. It is noticed that variation of meanstress is more detrimental than stress amplitude in controlling strain accumulation while the effect of stress amplitude is morepronounced than mean stress for the reduction of ratcheting life. The fracture surface morphology indicates typical striationformation in the crack propagation region along with overload failure. The bulk texture studies indicate that there is a transitionbetween ‘ϒ’ fiber and ‘ζ’ fiber during all loading conditions. The texture intensity is increased from 5.71 to 11.68 withprogressive ratcheting strain accumulation. Here also, influence of stress amplitude is more significant than the mean stress.

A two-fluid modeling of kinetic Alfvén wave turbulence

Kumar, Sanjay,Dwivedi, Navin Kumar,Sharma, R. P.,Moon, Y.-J. Springer-Verlag 2018 Astrophysics and space science Vol.363 No.10

Effect of MgO addition on physico-chemical, mechanical and thermal behaviour of Al/Si3N4 composite material developed via hybrid casting technique

Shashi Prakash Dwivedi,Ashok Kumar Mishra,V. R. Mishra 한양대학교 세라믹연구소 2019 Journal of Ceramic Processing Research Vol.20 No.6

In the present investigation, aluminium based composite material developed by using Si3N4 as primary reinforcement material and MgO as secondary reinforcement material by hybrid casting techniques. The microstructure of composite developed by hybrid casting technique showed a uniform distribution of Si3N4 and MgO particles in the AA2024 aluminium alloy. Maximum tensile strength and hardness were found to be 214.5 MPa and 78 BHN for heat-treated AA2024/7.5% Si3N4/5% MgO composite material. Minimum thermal expansion was also found for AA2024/7.5% Si3N4/5% MgO composite material. However, minimum corrosion loss was found for AA2024/10% Si3N4/2.5% MgO composite material. Though, toughness and ductility were reduced by adding the Si3N4 and MgO particles in AA2024 aluminium alloy. XRD analysis of AA2024/7.5% Si3N4/5% MgO composite material was also observed to see the effect of Si3N4 and MgO particles addition in AA2024 aluminium alloy.