Crystallite size controlled doping of transition metals (Co, Cu) in ZnO nanocrystals to investigate microstructural, optical, magnetic, and photocatalytic properties

Kalita Amarjyoti 한국물리학회 2023 Current Applied Physics Vol.52 No.-

In this report, Co and Cu doped ZnO nanocrystals with controlled crystallite size were synthesized. The formation of the hexagonal wurtzite phase is confirmed by Rietveld refinement of X-ray diffraction (XRD) patterns. Crystallite size ranges (17 nm–20 nm) obtained from XRD analysis are complemented with transmission electron microscopy (TEM) observation. The presence of E2high mode recognized the unchanged phase and good crystalline nature of the nanocrystals. Photoluminescence (PL) spectra of Co and Cu doped ZnO nanocrystals are related to zinc and oxygen based defect states. The quenching of PL intensity is due to the incorporation of Co and Cu in the ZnO nanocrystals. ESR results complement the decrease in ferromagnetic order as obtained by VSM measurement in both Co and Cu doped ZnO nanocrystals. The superior photocatalytic activity of Cu doped ZnO nanocrystals could be due to the higher electron trapping capability of Cu2+ ions.

Temporomandibular joint re-ankylosis: a case report and literature review

Kalita Flora,KV Arunkumar 대한구강악안면외과학회 2023 대한구강악안면외과학회지 Vol.49 No.4

Re-ankylosis is a common postoperative complication of temporomandibular joint (TMJ) ankylosis surgery. Various surgical options to prevent reankylosis, both with and without interpositional material, have been discussed in the literature. However, no standardized protocol has been suggested for management or prevention of TMJ ankylosis. This paper discusses the probable causes behind TMJ re-ankylosis and presents a case of unilateral TMJ re-ankylosis, which was managed by gap arthroplasty using an autologous abdominal dermal fat graft as an interpositional material and closely monitored for signs of relapse. Autologous fat graft acted as an effective barrier between the glenoid fossa and mandibular condyle, thus preventing dead space, hematoma and heterotrophic bone formation. A brief review of the literature and update on TMJ re-ankylosis are also presented.

Metamodel based multi-objective design optimization of laminated composite plates

Kalita, Kanak,Nasre, Pratik,Dey, Partha,Haldar, Salil Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.67 No.3

In this paper, a multi-objective multiparameter optimization procedure is developed by combining rigorously developed metamodels with an evolutionary search algorithm-Genetic Algorithm (GA). Response surface methodology (RSM) is used for developing the metamodels to replace the tedious finite element analyses. A nine-node isoparametric plate bending element is used for conducting the finite element simulations. Highly accurate numerical data from an author compiled FORTRAN finite element program is first used by the RSM to develop second-order mathematical relations. Four material parameters-${\frac{E_1}{E_2}}$, ${\frac{G_{12}}{E_2}}$, ${\frac{G_{23}}{E_2}}$ and ${\upsilon}_{12}$ are considered as the independent variables while simultaneously maximizing fundamental frequency, ${\lambda}_1$ and frequency separation between the $1^{st}$ two natural modes, ${\lambda}_{21}$. The optimal material combination for maximizing ${\lambda}_1$ and ${\lambda}_{21}$ is predicted by using a multi-objective GA. A general sensitivity analysis is conducted to understand the effect of each parameter on the desired response parameters.

Impact of Routine Histopathological Examination of Gall Bladder Specimens on Early Detection of Malignancy - A Study of 4,115 Cholecystectomy Specimens

Kalita, Dipti,Pant, Leela,Singh, Sompal,Jain, Gaurav,Kudesia, Madhur,Gupta, Kusum,Kaur, Charanjeet Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.5

Gall bladder carcinoma is the most common cancer of biliary tree, characterized by rapid progression and a very high mortality rate. Detection at an early stage, however, is indicative of a very good prognosis and prolonged survival. The practice of histopathological examination of gall bladder specimens removed for clinically benign conditions and its usefulness has been a subject of controversy. The present prospective study was carried out over a period of four years in order to find out the incidence of unsuspected gallbladder carcinoma in cholecystectomy specimens received in our histopathology laboratory and to analyze their clinico-pathological features. A total of 4,115 cases were examined. Incidentally detected cases comprised 0.44%, which accounted for 72% of all gall bladder carcinomas detected. The majority were in an early, surgically resectable stage. From the results of this study we recommend that in India and other countries with relatively high incidences of gall bladder carcinoma, all cholecystectomy specimens should be submitted to histopathology laboratory, as this is the only means by which malignancies can be detected at an early, potentially curable stage.

A response surface modelling approach for multi-objective optimization of composite plates

Kanak Kalita,Partha Dey,Milan Joshi,Salil Haldar 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.32 No.4

Despite the rapid advancement in computing resources, many real-life design and optimization problems in structural engineering involve huge computation costs. To counter such challenges, approximate models are often used as surrogates for the highly accurate but time intensive finite element models. In this paper, surrogates for first-order shear deformation based finite element models are built using a polynomial regression approach. Using statistical techniques like Box-Cox transformation and ANOVA, the effectiveness of the surrogates is enhanced. The accuracy of the surrogate models is evaluated using statistical metrics like R2, R2adj, R2pred and Q2F3. By combining these surrogates with nature-inspired multi-criteria decision-making algorithms, namely multi-objective genetic algorithm (MOGA) and multi-objective particle swarm optimization (MOPSO), the optimal combination of various design variables to simultaneously maximize fundamental frequency and frequency separation is predicted. It is seen that the proposed approach is simple, effective and good at inexpensively producing a host of optimal solutions.

Functionalization of multi-walled carbon nanotubes (MWCNTs) with nitrogen plasma for photovoltaic device application

Golap Kalita,Sudip Adhikari,Hare Ram Aryal,Rakesh Afre,Tetsuo Soga,Maheshwar Sharon,Masayoshi Umeno 한국물리학회 2009 Current Applied Physics Vol.9 No.3

Multi-walled carbon nanotubes (MWCNTs) placed under nitrogen (N2) and argon (Ar) microwave plasma in order to functionalize covalently their side walls with nitrogen containing groups. X-ray photoelectron spectroscopy (XPS) study shows surface modification of the MWCNTs with imine, amine, nitride and amide groups grafted on the side walls. Due to the functional groups, homogenous distribution of MWCNTs in solvent could be obtained. For photovoltaic device fabrication MWCNTs film was casted over n-Si wafer and poly(3-octylthiophene) solution was infiltered. Devices with functionalized MWCNTs show short circuit current density (Jsc), open circuit voltage (Voc), fill factor (FF) and power conversion efficiency (g) as 1.8 mA/㎠, 0.20 V, 24% and 0.086%, respectively. In the composite film functionalized MWCNTs facilitate photo induced charge separation and efficient holes transportation, suppressing recombination of photo generated charges. Multi-walled carbon nanotubes (MWCNTs) placed under nitrogen (N2) and argon (Ar) microwave plasma in order to functionalize covalently their side walls with nitrogen containing groups. X-ray photoelectron spectroscopy (XPS) study shows surface modification of the MWCNTs with imine, amine, nitride and amide groups grafted on the side walls. Due to the functional groups, homogenous distribution of MWCNTs in solvent could be obtained. For photovoltaic device fabrication MWCNTs film was casted over n-Si wafer and poly(3-octylthiophene) solution was infiltered. Devices with functionalized MWCNTs show short circuit current density (Jsc), open circuit voltage (Voc), fill factor (FF) and power conversion efficiency (g) as 1.8 mA/㎠, 0.20 V, 24% and 0.086%, respectively. In the composite film functionalized MWCNTs facilitate photo induced charge separation and efficient holes transportation, suppressing recombination of photo generated charges.

Weighted sum multi-objective optimization of skew composite laminates

Kanak Kalita,Uvaraja Ragavendran,Manickam Ramachandran,Akash Kumar Bhoi 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.69 No.1

Optimizing composite structures to exploit their maximum potential is a realistic application with promising returns. In this research, simultaneous maximization of the fundamental frequency and frequency separation between the first two modes by optimizing the fiber angles is considered. A high-fidelity design optimization methodology is developed by combining the high-accuracy of finite element method with iterative improvement capability of metaheuristic algorithms. Three powerful nature-inspired optimization algorithms viz. a genetic algorithm (GA), a particle swarm optimization (PSO) variant and a cuckoo search (CS) variant are used. Advanced memetic features are incorporated in the PSO and CS to form their respective variants-RPSOLC (repulsive particle swarm optimization with local search and chaotic perturbation) and CHP (co-evolutionary host-parasite). A comprehensive set of benchmark solutions on several new problems are reported. Statistical tests and comprehensive assessment of the predicted results show CHP comprehensively outperforms RPSOLC and GA, while RPSOLC has a little superiority over GA. Extensive simulations show that the on repeated trials of the same experiment, CHP has very low variability. About 50% fewer variations are seen in RPSOLC as compared to GA on repeated trials.

Eigenfrequencies of simply supported taper plates with cut-outs

Kanak Kalita,Salil Haldar 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.63 No.1

Free vibration analysis of plates is necessary for the field of structural engineering because of its wide applications in practical life. Free vibration of plates is largely dependent on its thickness, aspect ratios, and boundary conditions. Here we investigate the natural frequencies of simply supported tapered isotropic rectangular plates with internal cutouts using a nine node isoparametric element. The effect of rotary inertia on Eigenfrequencies was demonstrated by calculating with- and without rotary inertia. We found that rotary inertia has a significant effect on thick plates, while rotary inertia term can be ignored in thin plates. Based on comparison with literature data, we propose that the present formulation is capable of yielding highly accurate results. Internal cutouts at various positions in tapered rectangular simply supported plates were also studied. Novel data are also reported for skew taper plates.

Metamodel based multi-objective design optimization of laminated composite plates

Kanak Kalita,Pratik Nasre,Partha Dey,Salil Haldar 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.67 No.3

In this paper, a multi-objective multiparameter optimization procedure is developed by combining rigorously developed metamodels with an evolutionary search algorithm—Genetic Algorithm (GA). Response surface methodology (RSM) is used for developing the metamodels to replace the tedious finite element analyses. A nine-node isoparametric plate bending element is used for conducting the finite element simulations. Highly accurate numerical data from an author compiled FORTRAN finite element program is first used by the RSM to develop second-order mathematical relations. Four material parameters- E_1/E_2 , G_12/E_2 , G_23/E_2 and υ_12 are considered as the independent variables while simultaneously maximizing fundamental frequency, λ_1 and frequency separation between the 1st two natural modes, λ_21. The optimal material combination for maximizing λ_1 and λ_21 is predicted by using a multi-objective GA. A general sensitivity analysis is conducted to understand the effect of each parameter on the desired response parameters.

Biobased Epoxy Blends from Epoxidized Castor Oil: Effect on Mechanical, Thermal, and Morphological Properties

Sudha G. S.,Hemjyoti Kalita,Smita Mohanty,Sanjay Kumar Nayak 한국고분자학회 2017 Macromolecular Research Vol.25 No.5

In the present study, in-situ epoxidation was employed to prepare epoxidized castor oil (ECO). Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectra analysis were used to analyze the chemical structures of ECO. Biobased epoxy blends were synthesized from diglycidyl ether of bisphenol A (DGEBA) and ECO at variable wt% using triethylenetetramine as curing agent. The thermal, mechanical and morphological behavior of blends has been investigated. The morphological study showed homogeneous mixing of the ECO and DGEBA blends. The blend prepared using 20wt% of ECO showed optimum impact and flexural strength as compared with commercially available epoxy resin. The fracture toughness parameters, critical stress intensity (KIC) and the critical strain of blends were also observed to increase as compared with the virgin matrix which revealed enhancement in toughness. The tensile property of the blend reduced with the increasing ECO content which confirmed the fact that the addition of the high amount of ECO reduces the crosslink density of the biobased epoxy.