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Sandeep Sharma

    Sandeep Sharma

    We report the role of irradiation-induced defects and microstructure evolution in the wake of 1.05 MeV Xe 3+ ion irradiation on the structural and mechanical properties of single-phase face-centered cubic (FCC) structured NiCoCrFePd... more
    We report the role of irradiation-induced defects and microstructure evolution in the wake of 1.05 MeV Xe 3+ ion irradiation on the structural and mechanical properties of single-phase face-centered cubic (FCC) structured NiCoCrFePd high-entropy alloy (HEA). The defect evolution was investigated using positron annihilation Doppler broadening spectroscopy (PADBS), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), and nanoindentation techniques. Single-phase FCC structured NiCoCrFePd HEA remained structurally stable even upon irradiation to a very high fluence of 9 × 10 16 ions/cm 2. However, an anomalous reduction in the lattice constant, along with micro-strain relaxation and crystallite fragmentation was observed at the initial ion fluence of 1 × 10 16 ions/cm 2 , which are recovered upon irradiation at the higher ion fluence due to collapse of small-sized point defects into the large-sized dislocations and simultaneously irradiation-induced recrystallization. Ion fluence-dependent PADBS analysis revealed the formation of mono-vacancies at lower fluence which were saturated by recombination and evolution to large-size defects at successive higher ion fluence that is consistent with electron microscopic investigations. Measurement of mechanical properties showed that the hardness was initially increased by 57% upon irradiation at fluence 1 × 10 16 ions/cm 2 and then it was slightly reduced (~5%) at a higher fluence of 9 × 10 16 ions/cm 2 irradiation due to defect recombination and recrystallization which clearly shows the resistance of this HEA towards hardening. Thus, the present study provides a deeper understanding of the defect dynamics and their relation to the mechanical behavior of NiC-oCrFePd HEA, which is important for the development of radiation-resistant alloys for nuclear energy systems.
    Current availability of interactive technologies infrastructure such as internet bandwidth, increased processing power and connectivity through mobile devices at affordable costs have led to new concepts related to human living. Smart... more
    Current availability of interactive technologies infrastructure such as internet bandwidth, increased processing power and connectivity through mobile devices at affordable costs have led to new concepts related to human living. Smart cities, smart life and internet of things etc. are few such evolving research domains. A prominent concept among these is `Smart Home', which involves automation and interactive technologies. This paper proposes a multi-functional `Smart Home Automation System' (SHAS), where users can use voice-commands to control their home-appliances and gadgets, for different functionalities and purposes. The proposed system can be adapted to a user's voice and recognise the voice-commands, independent of the speaker's personal characteristics such as accent. The system is aimed to be cost-effective, flexible and robust. The voice command recognition is achieved using a dedicated hardware module and an Arduino micro-controller board for commands processing and control. Performance evaluation is carried out by developing a multi-functional miniature prototype of the SHAS. Results of the experiments conducted are quite promising. The prototype SHAS can be used for converting existing homes into smart homes at relatively low cost and with convenience.
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    Pretreatment of rice straw on pilot scale steam explosion has been attempted to achieve maximum sugar recovery. Three different reaction media viz. water, sulfuric acid and phosphoric acid (0.5%, w/w) were explored for pretreatment by... more
    Pretreatment of rice straw on pilot scale steam explosion has been attempted to achieve maximum sugar recovery. Three different reaction media viz. water, sulfuric acid and phosphoric acid (0.5%, w/w) were explored for pretreatment by varying operating temperature (160, 180 and 200°C) and reaction time (5 and 10min). Using water and 0.5% SA showed almost similar sugar recovery (∼87%) at 200 and 180°C respectively. However, detailed studies showed that the former caused higher production of oligomeric sugars (13.56g/L) than the later (3.34g/L). Monomeric sugar, followed the reverse trend (7.83 and 11.62g/L respectively). Higher oligomers have a pronounced effect in reducing enzymatic sugar yield as observed in case of water. Mass balance studies for water and SA assisted SE gave total saccharification yield as 81.8% and 77.1% respectively. However, techno-economical viability will have a trade-off between these advantages and disadvantages offered by the pretreatment medium.
    In children, complete loss of the bone fragment with intact periosteal sleeve may be followed by complete formation of the missing bone [1]. We report a rare injury pattern of the clavicle with a rarer outcome on conservative management.
    Contrast radiography of the alimentary canal was conducted in six adult sheep with barium sulfate (70% W/V, 25–30 ml/kg). A period of 12 hours was adequate for opacification of most parts of the gastrointestinal tract. The presence of... more
    Contrast radiography of the alimentary canal was conducted in six adult sheep with barium sulfate (70% W/V, 25–30 ml/kg). A period of 12 hours was adequate for opacification of most parts of the gastrointestinal tract. The presence of contrast medium in different parts of the alimentary canal was noted for as long as 60 hours. The right lateral view was adequate for visualization of most structures, but the typical laminar mucosal pattern of the omasum and the spiral mucosal folds of the abomasum were demonstrated better on the ventrodorsal view.
    Over a 5-year period, virological investigations for Japanese encephalitis (JE) were conducted in children presenting with acute encephalopathic illness. Clinical features of JE-positive patients (n = 116) were compared with patients in... more
    Over a 5-year period, virological investigations for Japanese encephalitis (JE) were conducted in children presenting with acute encephalopathic illness. Clinical features of JE-positive patients (n = 116) were compared with patients in whom the diagnosis could be excluded (n = 57). Multivariate analysis by logistic regression revealed that two clinical signs--central hyperpneic breathing pattern and extrapyramidal signs--were significant predictors of the diagnosis. Application of the model yielded a sensitivity of 41.3% and a specificity of 80.7% with positive and negative predictive values of 81.3 and 40.3%, respectively. This indicates that the model may be helpful in making the diagnosis but not in excluding it. The model should be further validated in different areas where the disease is prevalent.
    Takayasu aortoarteritis (TA) rarely affects the nervous system, but when it does, it usually manifests as cerebral ischemia or stroke. These strokes have mainly been attributed to stenotic extracranial vessels. Stenoses of intracranial... more
    Takayasu aortoarteritis (TA) rarely affects the nervous system, but when it does, it usually manifests as cerebral ischemia or stroke. These strokes have mainly been attributed to stenotic extracranial vessels. Stenoses of intracranial vessels, although rare in TA, can occur due to either embolization into the vessel or because of the vasculitic process itself. Intracranial aneurysms are very rare in patients with TA. Bilateral cavernous internal carotid artery (ICA) aneurysms are rarer. They have been reported following radiation therapy and in association with fibromuscular dysplasia and juvenile Paget disease. Bilateral mycotic intracavernous aneurysms also occur. Bilateral giant cavernous ICA aneurysms with carotid-cavernous fistula (CCF) consequent to rupture into the cavernous sinus in a case of TA are extremely unusual. We report a case that fulfilled both American College of Rheumatology and European League against Rheumatology criteria for TA. The patient had bilateral cave...
    Numerous reports implicate increased oxidative stress in the functional and structural changes occurring in the brain and other organs as a part of the normal aging process. Dietary restriction (DR) has long been shown to be... more
    Numerous reports implicate increased oxidative stress in the functional and structural changes occurring in the brain and other organs as a part of the normal aging process. Dietary restriction (DR) has long been shown to be life-prolonging intervention in several species. This study was aimed to assess the potential efficacy of late-onset short term DR when initiated in 21 months old male wistar rats for 3 months on the antioxidant defense system and lipid peroxidation, cellular stress response protein HSP 70 and synaptic marker protein synapsin 1 in discrete brain regions such as cortex, hypothalamus, and hippocampus as well as liver, kidney and heart from 24 month old rats. Age-associated decline in activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione, and elevated levels of lipid peroxidation was observed in brain and peripheral organ as well as increased expression of HSP 70 and reduction in synapsin 1 was observed in brain studied. Late-onset short term DR was effective in partially restoring the antioxidant status and in decreasing lipid peroxidation level as well as enhancing the expression of HSP 70 and synapsin 1 in aged rats. Late onset short term DR also prevented age-related neurodegeneration as revealed by Fluoro-Jade B staining in hippocampus and cortex regions of rat brain. Thus our current results suggest that DR initiated even in old age has the potential to improve age related decline in body functions.
    Hydroxychavicol isolated from the chloroform extraction of aqueous extract of Piper betle leaves showed inhibitory activity against oral cavity pathogens. It exhibited an inhibitory effect on all of the oral cavity pathogens tested (MICs... more
    Hydroxychavicol isolated from the chloroform extraction of aqueous extract of Piper betle leaves showed inhibitory activity against oral cavity pathogens. It exhibited an inhibitory effect on all of the oral cavity pathogens tested (MICs of 62.5 to 500 μg/ml) with a minimal bactericidal concentration that was twofold greater than the inhibitory concentration. Hydroxychavicol exhibited concentration-dependent killing of Streptococcus mutans ATCC 25175 up to 4× MIC and also prevented the formation of water-insoluble glucan. Interestingly, hydroxychavicol exhibited an extended postantibiotic effect of 6 to 7 h and prevented the emergence of mutants of S. mutans ATCC 25175 and Actinomyces viscosus ATCC 15987 at 2× MIC. Furthermore, it also inhibited the growth of biofilms generated by S. mutans and A. viscosus and reduced the preformed biofilms by these bacteria. Increased uptake of propidium iodide by hydroxychavicol-treated cells of S. mutans and A. viscosus indicated that hydroxychav...
    ABSTRACT This paper reports a non-contact, in-situ and non-destructive corrosion monitoring methodology for submerged plates using ultrasonic guided waves. Specific surface sensitive and core sensitive guided wave modes are utilized for... more
    ABSTRACT This paper reports a non-contact, in-situ and non-destructive corrosion monitoring methodology for submerged plates using ultrasonic guided waves. Specific surface sensitive and core sensitive guided wave modes are utilized for monitoring plates undergoing accelerated impressed current corrosion in the presence of chlorides. A combination of the selected guided wave modes could effectively discern various corrosion mechanisms occurring in plates. Along with the ultrasonic signals, mass loss, stress–strain behaviour and tensile strength of the plates at different stages of corrosion have been monitored. Algebraic relationships between the ultrasonic readings and other parameters have been developed. This investigation should be useful in developing a non-destructive technique for monitoring progressive corrosion in plates and assessing their deterioration in strength, stiffness and mass loss that would help in the estimation of residual life. Copyright © 2014 John Wiley & Sons, Ltd.