Showing papers by "Ankit Gupta published in 2021"

Size-dependent vibration response of porous graded nanostructure with FEM and nonlocal continuum model

Abstract: In the present paper, a refined trigonometric higher-order shear deformation theory has been presented with the conjunction of nonlocal theory for the vibrational response of functionally graded (FG) porous nanoplate. The displacement field is chosen based on assumptions that the out of the plane displacement consists of bending and shear components whereas the transverse shear-strain has nonlinear variation along the thickness direction. The number of unknown variables is four, as against five in other renowned shear deformation theories. The governing equations have been derived using Hamilton's principle. A generalized porosity model has also been developed to accommodate both even and uneven type of distribution of porosity in the FG nanoplates. The closed-form solution of simply-supported FG porous nanoplates is obtained and the results are compared with the available reported results. In finite element solution, a C0 continuous isoparametric quadrilateral element has been used with various conventional and unconventional boundary conditions. The effects of various parameters like small-scale effect, aspect ratio, volume fraction index, porosity volume fraction, and thickness ratio have been investigated. The significant influence of small-scale effects and porosity inclusions have been observed in the reported results. It has been reported that both closed-form and finite element solutions with the present theory can make accurate predictions of the free vibration response.

Mechanical benchmarking of additively manufactured continuous and short carbon fiber reinforced nylon

Abstract: Mechanical properties of fiber reinforced additive manufacturing (FRAM) parts are affected by the fiber size and orientation. Oriented fiber composite is most likely to produce better properties. T...

Vibration response of a geometrically discontinuous bi-directional functionally graded plate resting on elastic foundations in thermal environment with initial imperfections

Abstract: The present study includes the free vibration analysis of geometrically imperfect and discontinuous porous functionally graded bi-directional plate (B-FGP) resting on an elastic foundation in a the...

New hyper-variable SSRs for diversity analysis in mango (Mangifera indica L.)

Abstract: Whole genome sequence in mango offers unprecedented opportunities for genomics assisted crop improvement via enabling access to genome-wide genetic markers. In the present study, simple sequence repeats (SSRs) were predicted from genome sequence of mango. Based on the SSR length (? 50 bp), highly-variable mango SSRs (MSSRs) were sorted. A sub-set of 129 MSSRs was validated on a set of 24 diverse mango genotypes yielding marker validation and polymorphism of 88.96 and 85.27 per cent, respectively. One hundred and ten polymorphic markers were identified for the present set of mango genotypes. Polymorphic information content (PIC) ranged from 0.10 to 0.78 and the highest value was observed with MSSR133. The mean PIC value was 0.40 but 33 MSSR markers showed PIC values ? 0.5, suggesting that these markers can efficiently measure genetic diversity and serve for mapping of quantitative trait loci (QTLs) in mango. MSSRs data was further used for diversity analysis of mango genotypes belonging to different agro-ecological conditions including chance seedlings, landraces, exotic and indigenous germplasm and hybrids. Cluster analysis using UPGMA of 24 mango genotypes revealed that these MSSRs were informative in diversity analysis and distinguished mango genotypes based on their origin, parentage and embryo types. A novel set of 110 hyper-variable SSR markers have been added to the mango repository depicting usefulness in discriminating closely related mango germplasm and their use in mango improvement programme.

Geometric/microstructural imperfection sensitivity in the vibration characteristics of geometrically non-uniform functionally graded plates with mixed boundary conditions

Abstract: In the present article, the vibration response of geometrically imperfect functionally graded material (FGM) plates with geometric discontinuities and microstructural defects have been investigated...

Complexities of pyridoxine response in PNPO deficiency

Abstract: Pyridox(am)ine- 5- phosphate Oxidase deficiency (PNPO) is a rare cause of neonatal metabolic encephalopathy associated with refractory status epilepticus. We report a case of a premature neonate presenting with drug-resistant seizures beginning at 2 hours of life. The baby showed initial transient response to pyridoxine followed by recurrence. Genetic report confirmed the diagnosis of PNPO deficiency. A literature review on phenotypic variants in terms of response to pyridoxine is also presented along with a proposed algorithm to manage a case of suspected vitamin responsive epilepsy. This case highlights our limited understanding of why variation in response to treatment exists in children with PNPO deficiency.

Meso–macro-scale computational analysis of boron nitride nanotube-reinforced aluminium and epoxy nanocomposites: A case study on crack propagation:

Abstract: In this paper, an outline of mean-field homogenization and fracture toughness of boron nitride nanotube-reinforced aluminium and epoxy composites have been presented. The meso-scale material modell...

Homogenized modeling approach for effective property prediction of 3D-printed short fibers reinforced polymer matrix composite material

Abstract: The objective of this paper is to present the modeling approach for homogenizing the 3D-printed composite parts for the accurate prediction of effective mechanical properties. The Mori–Tanaka (MT) approach associated with two-step homogenization is applied to partially oriented short carbon fiber (SCF)-reinforced polycarbonate (SCF/PC)-based composites and compared with the experimental results. Detailed microstructural analysis was performed to investigate the variation in fiber length and bead dimensions that occurred due to change in fiber percentage (3%, 5%, 7.5%, and 10% by vol.). A two-step homogenization framework was performed in this research. Change in fiber length was considered in the first-step homogenization and change in bead dimensions was considered in the second step of homogenization approach to find the microscale and mesoscale constitutive properties of SCF/PC 3D-printed composite samples using the MT method respectively. Results of this study revealed that the stiffness of the composite samples increases with the increase in fiber percentage. As we increase the SCF, significant variations were observed in the fiber length and bead dimensions which also significantly affect the mechanical properties of 3D-printed composite parts. Results obtained after considering the fiber length and bead dimensions in mathematical calculation helps in reducing the error gap between the homogenized numerical and experimental results. It was also concluded that the prediction of Young’s modulus using higher fiber percentage has relatively low errors. Eventually, the properties attained from the respective approach help to find out the macro fields (average stress and average strain) in the 3D-printed composite samples.

Microstructure/geometric imperfection sensitivity on the thermo-mechanical nonlinear stability behavior of functionally graded plates using four variable refined structural kinematics:

Abstract: The present work deals with the nonlinear stability characteristics of geometrically imperfect shear deformable functionally graded plates (FGP) subjected to thermo-mechanical loads. The equilibriu...

Experimental Investigation and Comparative Study of Sintering of Microcrystalline Nickel Using Microwave and Conventional Method

Abstract: The present work has been conducted to investigate and compare the mass transport mechanism of Ni-powder particles in conventional and microwave sintering process. The linear shrinkage method was used to investigate the mass transport mechanism on the basis of estimated sintering exponent (n) at different temperatures. Both types of sintering were carried out at various temperatures, and the results revealed that microwave sintering provides better results of densification and shrinkage as compared to conventional sintering. Field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDX) analysis were carried out for the characterization of Ni-powder for microstructural and elemental analysis. The value of sintering exponent found through linear shrinkage method for conventional was 9.4791, 8.1836, 6.9013, 7.3286, 5.2006 and 4.9531 at 500 °C–1000 °C, respectively, and microwave sintering was 7.0972, 5.2957,5.2942 and 6.0934 at 500 °C—800 °C, respectively.

Mean-field homogenization coupled low-velocity impact analysis of nano fibre reinforced composites

Abstract: Finding lightweight materials that are suitable for high-strength impact application is imperative However, incorporating empirical methods for the same can be an exorbitant affair This study aims to obviate these experimental methods and replace them with a numerical approach to the problem using the finite element method (FEM) in tandem with mean-field homogenization CNT and BNNT nano-fillers were used in the polymer matrix for the sake of comparison of dynamical response The preliminary step involves finding material properties of composite panels having different configurations and concentration of nanofillers both computationally and experimentally Later, an explicit dynamic based finite element analysis was performed to simulate the low-velocity impact on each of the composite plate developed Finally, temporal responses of the plate such as contact force, displacement, and velocity after the impact were illustrated and compared for both CNT and BNNT composite plates for different heterogeneities of fibre

Successful Multimodality Management of Atypical Teratoid/Rhabdoid Tumour of the Lower Dorsal Spine with Spinal Drop Metastasis: Illustrated Review.

Abstract: INTRODUCTION Spinal atypical teratoid/rhabdoid tumour (AT/RT) is exquisitely rare and constitutes 2% of all AT/RTs. CASE PRESENTATION A 6-year-old boy presented with low backache for the last 5 months. MRI of the spine showed a 1.5 × 1.5 × 4.7 cm intradural extramedullary mass extending from D10 to D12, causing compression of the conus medullaris. With a preoperative diagnosis of ependymoma, a gross total resection (GTR) of tumour was performed. Post-operative histopathology showed AT/RT. The tumour cells were immunopositive for cytokeratin, epithelial membrane antigen, smooth muscle actin, and p53 and immunonegative for MIC2, desmin, glial fibrillary acidic protein, and INI1. Post-operative neuraxis MRI revealed post-operative changes (D10-D12) with a 9 mm enhancing lesion at L5-S1 junction suggesting drop metastasis. There was no lesion in brain. Cerebrospinal fluid cytology did not show any malignant cell. The metastatic work-up was normal. He received 3 cycles of chemotherapy with ICE regimen (ifosfamide, carboplatin, and etoposide). Subsequently, he received craniospinal irradiation (CSI)-36 Gy/20 fractions/4 weeks followed by focal boost to primary tumour bed and spinal drop metastasis-14.4 Gy/8 fractions/1.5 weeks. Thereafter, he received 3 more cycles of ICE regimen. End-of-treatment MRI spine showed post-op changes (D10-D12) and 38.9% reduction of the L5-S1 lesion suggesting partial response. Six monthly spinal MRI showed serial reduction of the metastatic lesion leading to complete response (CR) 1 year after completion of treatment. On last follow-up (30 months from the initial diagnosis), he was neurologically intact and in CR. CONCLUSION Multimodality management comprising GTR of tumour, CSI followed by focal boost, and multiagent chemotherapy (ICE) can lead to successful outcome in patients with this rare and aggressive spinal tumour.

A comparative study of blood transfusion services before and during COVID-19 pandemic and the challenges faced: retrospective study done at a tertiary care hospital in North Western India

Abstract: The aim of blood transfusion services is timely and uninterrupted supply of safe blood. SARS-COV-2 pandemic has created the major disruption worldwide at all levels of health care. In India till 31st December around 10.2 million cases of COVID-19 were diagnosed and 1.49 lakh deaths have been reported. In Rajasthan around 3.08 lakh cases of COVID-19 were diagnosed and 2696 deaths on record till 31st December. COVID-19 pandemic has affected the blood transfusion services too. Announcement of national lockdown by Government of India and Janta Curfew to control the spread of virus has affected blood bank services majorly. Reduction in blood donations due to less number of outdoor blood donation camps to avoid social gatherings as well as to maintain strict social distancing policies as per government guidelines caused shortage of blood. Sickness of staff and public health affected it adversely. Major challenges experienced were healthy blood donor recruitment, staff safety, inventory and consumable management. So policies were planned for prioritizing the patients in case ABSTRACT