309 results on '"N. Vijayan"'
Search Results
2. A comprehensive assessment on synthesis, growth, theoretical & optical properties of glycine zinc sulphate pentahydrate single crystal for third-order nonlinear optical applications
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null Kiran, N. Vijayan, Debabrata Nayak, Manju Kumari, null Vinod, Kapil Kumar, Pargam Vashishtha, N. Thirughanasambantham, V. Balachandran, B. Sridhar, and Govind Gupta
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Electrical and Electronic Engineering ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials - Published
- 2023
3. Investigation on Computational, Hirshfeld, Surface Morphology, Thermal, Shock Damage Threshold, and Phase Matching Properties of an Iminodiacetic Acid Single Crystal for Second Harmonic Generation
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Debabrata Nayak, N. Vijayan, Manju Kumari, null Kiran, N. Thirughanasambantham, V. Balachandran, Subhasis Das, and R. P. Pant
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General Physics and Astronomy - Published
- 2023
4. Growth and assessment of optical and non-linear optical properties of lithium sulphamate single crystal for optoelectronic applications
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Ravinder Kumar, N. Vijayan, Neha Gupta, Naghma Khan, Mahesh Kumar, Govind Gupta, Khushboo Singh, Aparajita Bandyopadhyay, and Amartya Sengupta
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Electrical and Electronic Engineering ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials - Published
- 2023
5. Unmasking of systemic lupus erythematosus in a patient with hemophagocytic lymphohistiocytosis- macrophage activation syndrome (HLA-MAS) and diffuse alveolar hemorrhage
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P. Sukhadiya, P. Kumar, D.S. Meena, A. Kumar P.H., N. Vijayan, P. Garg, and M.K. Garg
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Rheumatology - Abstract
Hemophagocytic lymphohistiocytosis (HLH) is a hyperinflammatory syndrome caused by macrophages and cytotoxic T cells with aberrant activation. The primary (genetic) form, which is caused by mutations that affect lymphocyte cytotoxicity and immune regulation, is most prevalent in children, whereas the secondary (acquired) form is prevalent in adults. Secondary HLH is commonly caused by infections or cancers, but it can also be caused by autoimmune disorders, in which case it is known as macrophage activation syndrome (MAS; or MAS-HLH). A 25-year-old female presented with a high-grade fever that lasted for two weeks. His laboratory results revealed pancytopenia, neutropenia, hypertriglyceridemia, hypofibrinogenemia, and hyperferritinemia. Based on the clinical presentation and laboratory findings, a provisional diagnosis of HLH has been made. A HLH protocol was utilized to treat the patient. During the course of hospitalization, systemic lupus erythematosus (SLE) was identified as the underlying cause. She improved dramatically after receiving an immunosuppressive regimen of etoposide, cyclosporine, and dexamethasone according to HLH protocol-2004 with individualized modifications. The clinician should be aware that HLH may be the initial manifestation of underlying SLE. Early diagnosis and aggressive, individualized treatment are the key to improving outcomes.
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- 2023
6. Role of Indian Reference Materials for the Calibration of Sophisticated Instruments
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Manju Kumari, N. Vijayan, Debabrata Nayak, null Kiran, and R. P. Pant
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Physics and Astronomy (miscellaneous) - Published
- 2022
7. Growth aspects and characteristic properties of L-ascorbic acid single crystal: potential candidate for nonlinear optical applications
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null Vinod, Anuj Krishna, N. Vijayan, Ravinder Kumar, null Kiran, Subhasis Das, S. Swarupa Tripathy, Govind Gupta, and Nahar Singh
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Electrical and Electronic Engineering ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials - Published
- 2023
8. Ink - based non-vacuum process of synthesis of multicomponent Cu2ZnSn (Se1-x,Sx)4 for use in low-cost photovoltaic absorbers
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N. Vijayan, Jaydev Sharma, Shailesh Sharma, Parul Chawla, Shefali Jain, and Mansoor Ahamed
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Materials science ,Polymers and Plastics ,Inkwell ,business.industry ,Photovoltaic system ,Process (computing) ,Optoelectronics ,business ,General Environmental Science - Published
- 2021
9. C-graphs - A Mixed Graphical Representation of Groups
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Sinu N. Vijayan and Anjaly Kishore
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Combinatorics ,Group (mathematics) ,General Mathematics ,Order (group theory) ,Mixed graph ,Adjacency list ,Element (category theory) ,Representation (mathematics) ,Upper and lower bounds ,Mathematics ,Vertex (geometry) - Abstract
Corresponding to each group Γ, a mixed graph G = (Γ,E,E′) called C-graph is assigned, such that the vertex set of G is the group itself. Two types of adjacency relations, that is, one way and two way communication is defined for vertices, to get a clear idea of the underlying group structure. An effort to answer the question, ‘Is there any relation between the order of an element in the group and degrees of the corresponding vertex in the C-graph’, by proposing a mathematical formula connecting them is made. Established an upper bound for the total number of edges in a C-graph G. For a vertex z in G, the concept Connector Edge CEz is defined, which convey some structural properties of the group Γ. The Connector Edge Set is defined for both a vertex z and the whole C-graph G, and is denoted as C E z and C E G respectively. Proposed the result, C E G = E if and only if |Γ| = 2n, n ∈ N. Finally, the properties of G, which the Connector Edge Set C E G carry out are discussed.
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- 2021
10. Gridded distribution of total suspended particulate matter (TSP) and their chemical characterization over Delhi during winter
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Ranu Gadi, Tuhin Kumar Mandal, Shivani, Priyanka Saxena, Lokesh Yadav, Chhemendra Sharma, Arnab Mondal, Rubiya Banoo, N. Vijayan, Sakshi Ahlawat, Sudhir Kumar Sharma, Ummed Singh Saharan, Akansha Rai, Ritu Jangirh, Pooja Yadav, Garima Kotnala, Anil Patel, Neeraj Rastogi, Martina Rani, Rahul Arya, and Nikki Choudhary
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Total organic carbon ,Pollution ,Chemistry ,Health, Toxicology and Mutagenesis ,media_common.quotation_subject ,General Medicine ,Particulates ,Aerosol ,Environmental chemistry ,Environmental Chemistry ,Ecotoxicology ,Enrichment factor ,Elemental carbon ,Biomass burning ,media_common - Abstract
In the present study, total suspended particulate matter (TSP) samples were collected at 47 different sites (47 grids of 5 × 5 km2 area) of Delhi during winter (January–February 2019) in campaign mode. To understand the spatial variation of sources, TSP samples were analyzed for chemical compositions including carbonaceous species [organic carbon (OC), elemental carbon (EC), and water-soluble organic carbon (WSOC)], water-soluble total nitrogen (WSTN), water-soluble inorganic nitrogen (WSIN), polycyclic aromatic hydrocarbons (16 PAHs), water-soluble inorganic species (WSIS) (F−, Cl−, SO42−, NO2−, NO3−, PO43−, NH4+, Ca2+, Mg2+, Na+, and K+), and major and minor trace elements (B, Na, Mg, Al, P, S, Cl, K, Ca, Ti, Fe, Zn, Cr, Mn, Cu, As, Pd, F, and Ag). During the campaign, the maximum concentration of several components of TSP (996 μg/m3) was recorded at the Rana Pratap Bagh area, representing a pollution hotspot of Delhi. The maximum concentrations of PAHs were recorded at Udhyog Nagar, a region close to heavily loaded diesel vehicles, small rubber factories, and waste burning areas. Higher content of Cl− and Cl−/Na+ ratio (>1.7) suggests the presence of nonmarine anthropogenic sources of Cl− over Delhi. Minimum concentrations of OC, EC, WSOC, PAHs, and WSIS in TSP were observed at Kalkaji, representing the least polluted area in Delhi. Enrichment factor
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- 2021
11. A novel orange-red Sm3+-doped CaSiO3 nanostructured phosphor derived from agro food waste materials for white light applications
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N. Vijayan, R. Prasada Rao, P. Abdul Azeem, and M. Krishnam Raju
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Diffraction ,Materials science ,Process Chemistry and Technology ,Doping ,Analytical chemistry ,chemistry.chemical_element ,Phosphor ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Samarium ,chemistry ,Materials Chemistry ,Ceramics and Composites ,Photoluminescence excitation ,Particle size ,Crystallite ,Monoclinic crystal system - Abstract
Trivalent samarium activated β-Wollastonite (β-CaSiO3:Sm3+) nanostructured phosphor powders have been synthesized by modified sol-gel method at various concentrations (0.0, 0.2, 0.4, 0.6, 0.8 and 1 mol %) employing rice husk ash (RHA) and eggshell (ES) as the precursors for SiO2 and CaO respectively. The powder x-ray diffraction peaks disclose structure of sintered samples as monoclinic structure with space group P1 21/c1. The average crystallite sizes were determined by Debye scherrer's formula in the range of 26–34 nm. The average particle size was 84.5 nm found from TEM images. The photoluminescence excitation (PLE) spectra recorded high intensity peak at 400 nm was owing to 6H5/2 → 4K11/2 transition. The emission (PL) spectra of prepared samples exhibit intense orange–red color emission peak at 602 nm due to 4G5/2 → 6H7/2 transition. All the prepared samples emission tuned towards white region of the CIE diagram with the increment of Sm3+ content. This new nanostructured phosphor material could be a probable candidate for white light display and solid-state lighting (SSL) applications.
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- 2021
12. In situ growth of an ethyl p-hydroxybenzoate single crystal by the vertical Bridgman technique: a potential nonlinear optical material for third-harmonic generation
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Debabrata Nayak, R. P. Pant, Manju Kumari, Nikita Vashistha, Mahesh Kumar, N. Vijayan, and Kiran
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Crystal ,Materials science ,Photoluminescence ,Rietveld refinement ,law ,Vickers hardness test ,Analytical chemistry ,Sapphire ,Grain boundary ,Laser ,Single crystal ,General Biochemistry, Genetics and Molecular Biology ,law.invention - Abstract
Optically transparent single crystals of ethyl p-hydroxybenzoate (EPHB) were successfully grown by the vertical Bridgman technique. The crystalline phase and unit-cell dimensions were obtained from powder X-ray diffraction using Rietveld analysis. The presence of defects and grain boundaries was investigated by high-resolution X-ray diffraction. The optical quality of the grown single crystal was assessed by UV–Vis and photoluminescent spectroscopies. A blue emission, with a bi-exponential decay time, was obtained from time-resolved photoluminescence upon laser excitation at 266 nm. The mechanical strength of the EPHB single crystal was studied by Vickers hardness testing. A decrease in the laser-damage threshold was observed with a nanosecond Nd:YAG laser source for increased pulse repetition rates. The third-order nonlinearity, nonlinear absorption coefficient and nonlinear refractive index were measured using the Z-scan technique with a femtosecond Ti:sapphire laser. The third-order nonlinear coefficient values for the grown crystal were compared with those of a potassium dihydrogen phosphate single crystal.
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- 2021
13. Elemental, Optical, and Time-Domain Terahertz Spectroscopy Studies on Methyl p-Hydroxybenzoate Single Crystal for THz Applications
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Dibakar Roy Chowdhury, Debabrata Nayak, Sudha Yadav, Govind Gupta, N. Vijayan, Pargam Vashishtha, Manju Kumari, Rajendra Pant, and Mukesh Jewariya
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Photoluminescence ,Materials science ,Terahertz radiation ,Analytical chemistry ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Terahertz spectroscopy and technology ,Crystal ,Materials Chemistry ,Emission spectrum ,Electrical and Electronic Engineering ,Spectroscopy ,Absorption (electromagnetic radiation) ,Single crystal - Abstract
Organic nonlinear-optical single-crystal methyl p-hydroxybenzoate (MPHB) is one of the potential candidates for use in terahertz applications. The focus of this work is to study the response of MPHB single crystal in the terahertz region of the electromagnetic spectrum using time-domain terahertz spectroscopy (THz-TDS). Single-crystal MPHB was grown by the conventional slow evaporation solution growth technique (SEST). The structural confirmation of the title compound was assessed by powder x-ray diffraction (PXRD) analysis. The optical bandgap of ingot crystal was calculated using Tauc’s equation based on ultraviolet–visible (UV–Vis) spectroscopy. The photoluminescence emission spectrum revealed a major emission in the blue region corresponding to 457 nm. The dominant color emission for the title compound was assessed by converting the major emission peak to a Commission Internationale de l’Eclairage (CIE) chromaticity diagram, which further confirmed the emission of blue light from the crystal. The dynamics of the photon emission and its decay time for the title compound were studied by time-resolved photoluminescence (TRPL). THz-TDS was performed in the range from 0.2 THz to 3.0 THz on the title single crystal to observe its optical absorption behavior in the THz energy range. The variation of the absorption coefficient at terahertz frequencies is also presented herein.
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- 2021
14. Compressive Behavioural Analysis of LM26/ZrB2 Composite Using Finite Element Method
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S. Syath Abuthakeer, S. N. Vijayan, Samson Jerold Samuel Chelladurai, A. Saiyathibrahim, and J. Nashreen
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- 2022
15. Seasonal variation and sources of carbonaceous species and elements in PM2.5 and PM10 over the eastern Himalaya
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Akansha Rai, Tuhin Kumar Mandal, Sudhir Kumar Sharma, Abhijit Chatterjee, Nikki Choudhary, Sauryadeep Mukherjee, N. Vijayan, and Abhinandan Ghosh
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Total organic carbon ,Chemistry ,Health, Toxicology and Mutagenesis ,General Medicine ,010501 environmental sciences ,Seasonality ,Mineral dust ,medicine.disease ,01 natural sciences ,Pollution ,Environmental chemistry ,medicine ,Environmental Chemistry ,Ecotoxicology ,Positive relationship ,Elemental carbon ,Biomass burning ,Vehicular Emissions ,0105 earth and related environmental sciences - Abstract
The study represents the seasonal characteristics (carbonaceous aerosols and elements) and the contribution of prominent sources of PM2.5 and PM10 in the high altitude of the eastern Himalaya (Darjeeling) during August 2018–July 2019. Carbonaceous aerosols [organic carbon (OC), elemental carbon (EC), and water soluble organic carbon (WSOC)] and elements (Al, Fe, Ti, Cu, Zn, Mn, Cr, Ni, Mo, Cl, P, S, K, Zr, Pb, Na, Mg, Ca, and B) in PM2.5 and PM10 were analyzed to estimate their possible sources. The annual concentrations of PM2.5 and PM10 were computed as 37±12 μg m−3 and 58±18 μg m−3, respectively. In the present case, total carbonaceous species in PM2.5 and PM10 were accounted for 20.6% of PM2.5 and 18.6% of PM10, respectively, whereas trace elements in PM2.5 and PM10 were estimated to be 15% of PM2.5 and 12% of PM10, respectively. Monthly and seasonal variations in mass concentrations of carbonaceous aerosols and elements in PM2.5 and PM10 were also observed during the observational period. In PM2.5, the annual concentrations of POC and SOC were 2.35 ± 1.06 μg m−3 (66% of OC) and 1.19±0.57 μg m−3 (34% of OC), respectively, whereas annual average POC and SOC concentrations in PM10 were 3.18 ± 1.13 μg m−3 (63% of OC) and 2.05±0.98 μg m−3 (37% of OC), respectively. The seasonal contribution of POC and SOC were ranging from 55 to 77% and 33 to 45% of OC in PM2.5, respectively, whereas in PM10, the seasonal contributions of POC and SOC were ranging from 51 to 73% and 37 to 49% of OC, respectively. The positive relationship between OC & EC and OC & WSOC of PM2.5 and PM10 during all the seasons (except monsoon in case of PM10) indicates their common sources. The enrichment factors (EFs) and significant positive correlation of Al with othe crustal elements (Fe, Ca, Mg, and Ti) of fine and coarse mode aerosols indicate the influence of mineral dust at Darjeeling. Principal component analysis (PCA) resolved the four common sources (biomass burning + fossil fuel combustion (BB + FFC), crustal/soil dust, vehicular emissions (VE), and industrial emissions (IE)) of PM2.5 and PM10 in Darjeeling.
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- 2021
16. Overview on L-asparagine monohydrate single crystal: A non-essential amino acid
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Naghma Khan, N. Vijayan, Ravinder Kumar, and Neha Gupta
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Physics and Astronomy (miscellaneous) ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials - Abstract
This paper reviews the growth and properties of L-asparagine monohydrate (L-ASPM) single crystal. The growth technique by which a well-defined bulk-sized single crystal can be grown is also reported. The various reported studies done over titled crystal signify its suitability for various optoelectronic applications. This paper also includes few derivative compounds of L-asparagine (L-ASP), their structural review has also been incorporated to evaluate its structural bonding and atomic arrangement. Various advanced characterization and their outcomes were also discussed in detail from all the available reported literature which mainly emphasizes on the vast applicability of the crystal. The L-ASPM single crystal is a potential candidate to be used in various optical applications.
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- 2022
17. Investigations on Crystalline Perfection, Raman Spectra and Optical Characteristics of Transition Metal (Ru) Co-Doped Mg:LiNbO3 Single Crystals
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S. Ganesamoorthy, B. Riscob, Ashwini Kumar Karnal, Rajeev Bhatt, N. Vijayan, M K Raseel Rahman, Lekha Nair, Indranil Bhaumik, and G. Bhagavannarayana
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Materials science ,Dopant ,Band gap ,General Chemical Engineering ,Lithium niobate ,Analytical chemistry ,General Chemistry ,Chemistry ,symbols.namesake ,chemistry.chemical_compound ,Absorption edge ,chemistry ,Absorption band ,symbols ,Direct and indirect band gaps ,Raman spectroscopy ,Absorption (electromagnetic radiation) ,QD1-999 - Abstract
Congruent lithium niobate single crystals with a Ru:Mg co-dopant have been successfully grown using the Czochralski technique from the melt containing 0.02 mol % Ru with Mg of two varied concentrations (4.0 and 6.0 mol %). The effects of Ru and Mg co-doping on the crystalline quality were determined by high-resolution X-ray diffractometry, which confirmed that the crystalline quality is good and that the dopants are statistically distributed in the crystal. The Raman scattering analysis shows no change in the lattice vibration except a slight change in the peak width and intensity due to more asymmetry in the molecular charge, which leads to enhancement of the polarizability. The optical transmission spectra indicate that both the crystals have high optical transparency in the visible region, with a shift of the absorption edge toward shorter wavelengths, as compared to un-doped LN. The weak absorption band observed below 400 nm is attributed to Ru ions. The influence of co-doping in the electronic band gap energies is calculated by the Tauc relation. The refractive index is measured by using a prism coupler at two wavelengths (532 and 1064 nm). The calculated absorption coefficients and direct and indirect band gap energies for both the samples are found to be nearly the same within experimental error. A decrease in the birefringence is observed for the Ru:Mg(6 mol %) doped sample. The observed slight reduction in refractive indices with Ru:Mg co-doping is consistent with a rise in band gap energy, which is related to the change in absorption edge to the lower wavelength. The second harmonic generation (SHG) efficiency is measured by the Kurtz and Perry powder method, and a decrease in SHG efficiency for Ru:Mg(6 mol %) is observed.
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- 2021
18. Influence of l-Phenylalanine doping on potassium dihydrogen phosphate: crystal growth, structural, optical and mechanical traits
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G. Swati, T. Kamalesh, G. Bhagavannarayana, N. Vijayan, G. Durgababu, K.K. Maurya, and G. J. Nagaraju
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010302 applied physics ,Materials science ,Photoluminescence ,Dopant ,Doping ,Analytical chemistry ,Second-harmonic generation ,Crystal growth ,Condensed Matter Physics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,0103 physical sciences ,Crystallite ,Electrical and Electronic Engineering ,Powder diffraction ,Visible spectrum - Abstract
Potassium dihydrogen phosphate (KH2PO4; KDP) is a well known nonlinear optical (NLO) material for optoelectronic, laser technology and fiber optical communication device applications. In a view to yeild better device properties, l-Phenylalanine (l-Phe) aminoacid doped KDP (LKDP) crystals with different dopant concentrations (0.5 mol%, 1 mol% and 2 mol %) were grown by slow evaporation solution technique (SEST). The grown crystals were powdered of micron size crystallites and subjected to powder X-ray diffraction (PXRD). In PXRD spectra, a few peaks with increasing intensity were observed in LKDP crystals when compared to pure KDP, revealing the effect of incorporation of dopants in the crystalline matrix of KDP and the enhancement of growth rate along [100] direction. FT-IR spectrum confirms the incorparation of dopant in KDP crystalline matrix with the presence of different vibrational modes of assignments belongs to L-Phe. To study the crystalline perfection of pure and doped crystals, the high-resolution X-ray diffraction (HRXRD) was employed and the crystalline perfection was found to be reasonably good with relatively low values of FWHM. UV–Vis-NIR spectroscopy results show significant increase in optical transmission up to ~ 80% from ~ 60% (pure KDP) in the entire visible spectrum of l-Phe doped KDP at low doping concentration. However, it was decreased to ~ 70% when we increase the dopant concentration by 2 mol% and suggests that if we increase the dopant (l-Phe) concentration above an optimal value in KDP, the transmission decreases. The Photoluminescence (PL) spectrum reveals high crystalline perfection at low concentration of dopants as observed by the sharp peaks. The weak green emission peak for sample with higher dopant concentrations indicates the segregation of doped molecules at the structural grain boundaries as observed in the HRXRD studies. The mechanical strength of pure and doped KDP crystals with increasing dopant concentration has been studied and found that the hardness was increased slightly due to doping. The powdered sample of micron size particle made from as grown crystals were subjected to Kurtz powder technique to observe the relative second harmonic generation (SHG) efficiency in comparison with the pure KDP. These results reveal significant enhancement of SHG efficiency with increasing doping concentration up to 2 mol% in KDP crystals which is 1.31 times to that of pure KDP.
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- 2021
19. Studies on the third-order nonlinear behaviour of Itaconic acid single crystal using femto-second laser
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Pargam Vashishtha, Rajendra Pant, S. Das, Mahesh Kumar, Nikita Vashishtha, Manju Kumari, N. Vijayan, Govind Gupta, and Debabrata Nayak
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010302 applied physics ,Resistive touchscreen ,Materials science ,Evaporation ,Analytical chemistry ,Condensed Matter Physics ,Laser ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention ,Crystal ,Nonlinear system ,Wavelength ,chemistry.chemical_compound ,chemistry ,law ,0103 physical sciences ,Itaconic acid ,Electrical and Electronic Engineering ,Single crystal - Abstract
This work focuses on the bulk growth of Itaconic acid (ITA) single crystal from aqueous solution by slow evaporation solution growth technique. The detailed structural, optical, laser studies have been carried out for the title compound by adopting different instrumentation techniques. The cut-off wavelength of ITA crystal was obtained at 268 nm shows good nonlinear response. From the PL measurement, the high intense emission peak was observed at 442 nm corresponds to blue emission. The dominant emission colour of the grown specimen was estimated by CIE plot. The fast and slow decay of ITA single crystal were studied by time resolved PL. The laser resistive nature was examined by Nd-YAG laser and found that it is having good laser damage threshold (LDT) property. The third-order nonlinear optical behaviour of ITA crystal has been analyzed with the help of a femto-second laser using Z-scan technique. The value of various parameters like nonlinear refractive index (n2) and nonlinear absorption coefficient (β) is estimated using the theoretical calculations. The values of n2 and β were found to be 3.13 $$\times$$ 10–17 cm2/W and 1.57 $$\times$$ 10–12 cm/W, respectively. Such values of nonlinear parameters shows that grown crystal can be useful in optoelectronics applications.
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- 2021
20. Significance of Reference Materials for Calibration of Powder X-ray Diffractometer
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Rajendra Pant, Dinesh K. Misra, N. Vijayan, Manju Kumari, and Debabrata Nayak
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Identification (information) ,Accuracy and precision ,Certified reference materials ,Physics and Astronomy (miscellaneous) ,Component (UML) ,Systems engineering ,Calibration ,Field (computer science) ,Characterization (materials science) ,Diffractometer - Abstract
The scientific research and new innovations are associated with the accurate and precise measurements which are crucial for operation of recent civilization. In order to maintain the precision and accuracy in analytical measurements, Reference Materials and Certified Reference Materials (CRMs) play a vital role for improving the measurement capability to obtain the property value close to its true value which in turn revamps the overall growth of country for better quality of life. Certified Reference Materials are basically used to assess the performance of analytical procedures and laboratory apparatus for authentic measurement data. In recent scientific world, many sophisticated instruments are emerging with their various facets of measurement capabilities to cater the need of high end research in the field of academia and industries. In recent years, powder X-ray diffraction (PXRD) has been shown as the most powerful characterization and non-destructive technique to explore the structural investigation in terms of phase identification, size of a unit cell, volume fraction of phases, site occupancy of different elemental component, anti-site defects in materials and having many more other applications. The identification of mentioned information from PXRD instrument is a basic need in material science, geology, polymer, forensic science and environment etc. This article focuses on the importance of CRMs for calibrating the instruments and validation of analytical methods. Also the article explicitly discuss about the importance and applications of PXRD technique together with the role of National Physical Laboratory, India the national institute of measurement NMI of India.
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- 2021
21. Synthesis growth and studies on optical, thermal and terahertz analyses of bulk size sodium acid phthalate single crystal: a metal–organic material for nonlinear optical applications
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Subhash Nimanpure, Mahak Vij, Govind Gupta, N. Vijayan, Mukesh Jewariya, Manju Kumari, Rajendra Pant, Pargam Vashishtha, and Debabrata Nayak
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Photoluminescence ,Materials science ,Analytical chemistry ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,010406 physical chemistry ,0104 chemical sciences ,Thermogravimetry ,Crystal ,Differential scanning calorimetry ,Orthorhombic crystal system ,Physical and Theoretical Chemistry ,0210 nano-technology ,Refractive index ,Single crystal ,Powder diffraction - Abstract
Optical grade semi-organic single crystal of sodium acid phthalate (NaAP) was synthesized, and the crystals were harvested by slow evaporation solution growth technique (SEST) in an ambient condition. The titled compound is a promising material for nonlinear optical (NLO) applications and crystallized in non-centrosymmetric system. The structural information of the above-mentioned crystal was investigated by powder X-ray diffraction (PXRD), which reveals that it belongs to orthorhombic structure and B2ab space group. The presence of defects in the harvested crystal was assessed by high-resolution X-ray diffraction (HRXRD) and found that grown single crystal is moderately good. The optical behaviour of NaAP crystal was examined by UV–Vis, photoluminescence (PL) and time-resolved PL (TRPL), respectively. Thermal response and stability of the title compound were tested using thermogravimetry (TG), derivative thermogravimetry (DTG) and differential scanning calorimetry (DSC) analyses. The coefficient of thermal expansion (CTE) was evaluated using thermomechanical analyzer (TMA). The third-order NLO properties of NaAP single crystal had been evaluated by Z-scan method. The two-photon absorption coefficient (β) was calculated from open-aperture curve of Z-scan. The nonlinear study reveals that NaAP crystal is an appropriate choice in optical limiting usage. Terahertz (THz) time domain spectroscopy was used to study optical characteristics like refractive index and absorption coefficient of NaAP single crystal.
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- 2020
22. Effect of dyes on the growth, structural, morphological, optical, mechanical and dielectric properties of Sulphamic acid single crystal
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N. Renuka, R. Ramesh Babu, N. Vijayan, and P. Baskaran
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- 2022
23. Growth and Characterization of Single Crystals of l-Histidine Hydrochloride Monohydrate for Nonlinear Optical Applications
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Sabyasachi Banerjee, Sudha Yadav, Subhash Nimanpure, Dibakar Roy Chowdhury, Naghma Khan, Rina Sharma, Bhupendra K. Sharma, N. Vijayan, Girija Moona, Debabrata Nayak, Mukesh Jewariya, and Manju Kumari
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010302 applied physics ,Materials science ,Analytical chemistry ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Electronic, Optical and Magnetic Materials ,Terahertz spectroscopy and technology ,Crystal ,symbols.namesake ,0103 physical sciences ,Materials Chemistry ,symbols ,Orthorhombic crystal system ,Electrical and Electronic Engineering ,Fourier transform infrared spectroscopy ,0210 nano-technology ,Raman spectroscopy ,Single crystal ,Refractive index ,Powder diffraction - Abstract
In the present study, we have focused on the growth of semi-organic single crystals, as they play a vital role in the generation of a terahertz pulse and its potential applications. The single crystals of l-histidine hydrochloride monohydrate (LMHCL) were grown by slow evaporation solution growth by using deionized water as a solvent in a controlled atmosphere. Good quality crystals of the required size were obtained within 2 weeks. To estimate the lattice dimensions and get the structural information, powder x-ray diffraction (PXRD) study was performed in which we have found that the crystal belongs to the orthorhombic crystal system with space group P212121. The functional groups and the corresponding vibrational mode were confirmed using Fourier transform infrared (FTIR) and Raman spectroscopy, respectively. To study the optical properties UV–Vis transmission spectrum and photoluminescence (PL) were recorded. It was observed that the single crystal has a high value of transmission over a long range of wavelength which signifies that the crystal is a good candidate for nonlinear optical (NLO) applications. The UV cut-off wavelength is found to be 236 nm. The grown single crystals were studied by time-domain terahertz spectroscopy (THz-TDS) for photonic applications and the refractive indices were calculated and it is found that the refractive index is nearly equal to 3.4.
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- 2020
24. Investigating the seasonal variability in source contribution to PM2.5 and PM10 using different receptor models during 2013–2016 in Delhi, India
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Sudhir Kumar Sharma, Srishti Jain, Tuhin Kumar Mandal, and N. Vijayan
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Total organic carbon ,Multivariate statistics ,Health, Toxicology and Mutagenesis ,Mixed type ,General Medicine ,010501 environmental sciences ,Atmospheric sciences ,01 natural sciences ,Pollution ,Principal component analysis ,Environmental Chemistry ,Environmental science ,Mass concentration (chemistry) ,Elemental carbon ,Biomass burning ,Vehicular Emissions ,0105 earth and related environmental sciences - Abstract
The present work deals with the seasonal variations in the contribution of sources to PM2.5 and PM10 in Delhi, India. Samples of PM2.5 and PM10 were collected from January 2013 to December 2016 at an urban site of Delhi, India, and analyzed to evaluate their chemical components [organic carbon (OC), elemental carbon (EC), water-soluble inorganic components (WSICs), and major and trace elements]. The average concentrations of PM2.5 and PM10 were 131 ± 79 μg m−3 and 238 ± 106 μg m−3, respectively during the entire sampling period. The analyzed and seasonally segregated data sets of both PM2.5 and PM10 were used as input in the three different receptor models, i.e., principal component analysis-absolute principal component score (PCA-APCS), UNMIX, and positive matrix factorization (PMF), to achieve conjointly corroborated results. The present study deals with the implementation and comparison of results of three different multivariate receptor models (PCA-APCS, UNMIX, and PMF) on the same data sets that allowed a better understanding of the probable sources of PM2.5 and PM10 as well as the comportment of these sources with respect to different seasons. PCA-APCS, UNMIX, and PMF extracted similar sources but in different contributions to PM2.5 and PM10. All the three models extracted 7 similar sources while mutually confirmed the 4 major sources over Delhi, i.e., secondary aerosols, vehicular emissions, biomass burning, and soil dust, although the contribution of these sources varies seasonally. PCA-APCS and UNMIX analysis identified a less number of sources (besides mixed type) as compared to the PMF, which may cause erroneous interpretation of seasonal implications on source contribution to the PM mass concentration.
- Published
- 2020
25. Synthesis and growth of l-tyrosine hydrobromide and its characterization for optoelectronic applications
- Author
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Manju Kumari, N. Vijayan, S. Das, Rajendra Pant, Sudha Yadav, Eisha Sharma, and Debabrata Nayak
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010302 applied physics ,Photoluminescence ,Materials science ,business.industry ,Second-harmonic generation ,Condensed Matter Physics ,Laser ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention ,Thermogravimetry ,Crystal ,Differential scanning calorimetry ,law ,0103 physical sciences ,Optoelectronics ,Electrical and Electronic Engineering ,business ,Single crystal ,Powder diffraction - Abstract
A semi-organic l-tyrosine hydrobromide (LTHB) nonlinear optical single crystal has been harvested using slow evaporation solution technique (SEST) at atmospheric conditions. The ingot has under gone for different characterisations to check its appropriateness for device fabrications. The structural conformation and unit cell dimensions have been estimated using powder X-ray diffraction (PXRD) method. The prominent peaks of PXRD have been indexed and it shows that crystal having non-centrosymmetric in nature with nonlinear optical application in second harmonic generation (SHG). Fourier-transform infrared spectroscopy (FTIR) analysis has been employed to characterise as grown crystal to know about the presence of various functional group in it. The crystalline quality and defects during the growth have been inspected by high resolution X-ray diffraction (HRXRD) technique. Optical studies have been carried out using UV–Vis and photoluminescence (PL) analysis. From UV–Vis measurement, we found that the material exhibits lower cut off wavelength with a high transparency window which is suitable for nonlinear optical (NLO) and optoelectronic applications. A detailed discussion of thermo gravimetric (TG) and derivative thermogravimetry (DTG) along with differential scanning calorimetry (DSC) has been presented to know about the thermal behaviour of LTHB crystal. The thermo mechanical analyser (TMA) which is useful to evaluate the coefficient of thermal expansion (CTE) of the grown crystal has been performed. Laser damage threshold (LDT) density has been noticed to check its strength for high intense laser. The optical, structural, thermal and phase matching studies of titled crystal establish the suitability of this material for optoelectronics and NLO device applications.
- Published
- 2020
26. Sulphamic acid: potential single crystal for nonlinear optical applications
- Author
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Manju Kumari, Naghma Khan, N. Vijayan, Ravinder Kumar, Ritu Srivastava, Mukesh Jewariya, and Sonia
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010302 applied physics ,Materials science ,Photoluminescence ,Terahertz radiation ,Analytical chemistry ,Physics::Optics ,Molar absorptivity ,Condensed Matter Physics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Ellipsometry ,0103 physical sciences ,Emission spectrum ,Electrical and Electronic Engineering ,Spectroscopy ,Single crystal ,Refractive index - Abstract
A bulk-sized single crystal of sulphamic acid (SA) was grown by the solution growth technique. The lattice dimensions and the plane’s identification of the grown crystal were confirmed with powder X-ray diffraction. High-resolution X-ray diffraction was employed to observe crystalline perfection that was found fairly good. The optical transmission studies reveal its suitability for optical applications in the complete UV–visible region of the electromagnetic spectrum. Bandgap calculations and other optical parameters like absorption and extinction coefficient were calculated to scrutinize its optical characteristics. The photoluminescence emission spectrum was recorded for the corresponding excitation wavelength to reveal the crystal behavior and energy gap transitions. The presence of the titled compound was examined through FTIR spectroscopy. Ellipsometry study was also carried out for the measurement of linear refractive index (n) and also for the extinction coefficient (K). Z-scan studies have been examined to reveal third-order nonlinear optical behavior and calculated the value of its nonlinear absorption coefficient (β). The Terahertz response of the grown crystal was analyzed by the terahertz time-domain spectroscopy. Observed results showed that SA crystal is a good aspirant for NLO applications.
- Published
- 2020
27. Variation of carbonaceous species and trace elements in PM10 at a mountain site in the central Himalayan region of India
- Author
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N. Vijayan, Garima Kotnala, Nikki Choudhary, Priyanka Srivastava, Manish Naja, Tuhin Kumar Mandal, and Sudhir Kumar Sharma
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Total organic carbon ,Atmospheric Science ,010504 meteorology & atmospheric sciences ,Continental crust ,010501 environmental sciences ,Mineral dust ,01 natural sciences ,Altitude ,Environmental chemistry ,Environmental Chemistry ,Environmental science ,Trajectory analysis ,Biomass burning ,Air mass ,0105 earth and related environmental sciences ,Linear trend - Abstract
Observations of carbonaceous species [organic carbon (OC), elemental carbon (EC), water soluble organic carbon (WSOC), carbonaceous aerosols (CAs) and secondary organic carbon (SOC) ] and trace elements (As, Cr, Ni, Zn, Na, Mg, Al, P, K, Ca, Ti, Fe, and Mn) in PM10 are made over a high altitude site (ARIES, Nainital, 29.4° N, 79.5° E, ~1958 m amsl) in the central Himalayan region during October 2018−February 2019 to explore their possible sources. The average concentrations of PM10, OC, EC, WSOC, CA and SOC were recorded as 44±13 µg m-3, 3.66±1.26 µg m-3, 1.29±0.61 µg m-3, 2.28±0.76 µg m-3, 7.15±1.96 µg m-3 and 1.45±0.73 µg m-3, respectively during the study period. The concentrations of PM10, OC, EC, WSOC, CAs and SOC were significantly varied during autumn (October-November) and winter (December-February) seasons. During both the seasons, significant positive linear trend between OC & EC and OC & WSOC have been observed which is indicative of their common sources of carbonaceous aerosols at the study site. WSOC/OC ratio was estimated as 0.56 and 0.67 during autumn and winter, respectively suggested that the biomass burning could be one of the major sources of carbonaceous aerosols at Nainital. The significant positive correlation of PM10 with crustal elements (Al, Fe, Ca, Mg and Ti) as well as correlation of Al with other crustal elements (Fe, Ca, Mg and Ti) indicates the abundance of mineral dust at the sampling site. The observed Fe/Al ratio (1.07) also indicates mineral dust as a source at the sampling site, similarly, Ca/Al ratio (1.36) indicates that aerosols over this region is rich in Ca mineral as compared to average continental crust. Principal component analysis (PCA) identified the contribution of crustal/soil dust, biomass burning and industrial emissions to the PM10 over the central Himalayan region of India. Five days back trajectory analysis indicates that the air mass impacting the sampling site is from local surrounding area in Uttrakhand as well from Himachal Pradesh, Jammu & Kashmir, Ingo Gangetic Plain (IGP) region, Pakistan, Afghanistan region and Thar Desert.
- Published
- 2020
28. Single crystal growth of l-tartaric acid and its characterization for optical applications
- Author
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Anuj Krishna, Mukesh Jewariya, Ravinder Kumar, Girija Moona, Kopal Shandilya, Sudha Yadav, Naghma Khan, Samridhi Chopra, and N. Vijayan
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010302 applied physics ,Diffraction ,Photoluminescence ,Materials science ,Analytical chemistry ,Physics::Optics ,Infrared spectroscopy ,Condensed Matter Physics ,Laser ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention ,Crystal ,law ,0103 physical sciences ,Transmittance ,Electrical and Electronic Engineering ,Spectroscopy ,Single crystal - Abstract
An optical material is a fundamental in the field of information along with measurement of laser applications. Crystals of organic compounds are very well known for its highly efficient behavior towards the optical activities. In the present study, slow evaporation solution growth technique has been adopted for the growth of l-tartaric acid (LTA). The phase and structural information was assessed with powder X-ray diffraction and grown single crystal’s quality was tested through high resolution X-ray diffraction and found to be reasonably good. The composition bonding between the molecules was revealed out by Fourier-Transform Infrared Spectroscopy method. The Ultraviolet–Visible spectroscopy exposes the excellent transmittance properties of LTA crystal. Photoluminescence spectrum shows strong emission in the violet region. Optical properties are measured to know its behavior towards electromagnetic spectrum which is further analyzed by ultrafast pump probe spectrometry and the determination of non-linear optical absorption coefficient was also taken into account with respect to the absorbance spectra. Moreover, Vickers microhardness studies were carried out to check its mechanical behavior.
- Published
- 2020
29. Nonlinear optical single crystals for terahertz generation and detection
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Sudha Yadav, Manju Kumari, Debabrata Nayak, Girija Moona, Rina Sharma, N. Vijayan, and Mukesh Jewariya
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Physics and Astronomy (miscellaneous) ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials - Abstract
Nonlinear optical (NLO) single crystals with high quality are the pillars for the development of new devices that fulfil the demands of society. Nowadays, NLO single crystals are very attractive for the photonic applications particularly for terahertz (THz) photonics. The reason for their popularity is that these crystals can produce very powerful and ultra wideband THz waves due to their high nonlinear susceptibility. In this review paper, we deal with the challenges and progresses in the evolution of NLO single crystals for THz wave generation and detection. Here, we review the single crystal growth that how and by which method single crystal is grown. We summarize the structures, intermolecular and intramolecular interactions, their properties and how they generate and detect the THz waves. Widely used single crystals at present are DAST, BNA, OH1, amino acid-based single crystals, etc.
- Published
- 2022
30. Indian Reference Materials for Calibration of Sophisticated Instruments
- Author
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N. Vijayan, Pallavi Kushwaha, Asit Patra, Rachana Kumar, Surinder Pal Singh, Sandeep Singh, Anuj Krishna, Manju Kumari, Debabrata Nayak, and Nahar Singh
- Published
- 2022
31. Numerical analysis of impact behaviour of LM26/ZrB2 composite using finite element method
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S. N. Vijayan, Samson Jerold Samuel Chelladurai, S. Karthik, R. Mohammed Saliek, S. Mohamed Mansoor, and L. Neelakandan
- Published
- 2022
32. Predictors of locoregional control in stage I/II oral squamous cell carcinoma classified by AJCC 8th edition
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Krishnakumar Thankappan, Samskruthi Murthy, Sivakumar Vidhyadharan, Smitha N. Vijayan, Narender Kumar, Ajit Nambiar, Deepak Balasubramanian, Narayana Subramaniam, and Subramania Iyer
- Subjects
Adult ,Male ,Oncology ,medicine.medical_specialty ,Multivariate analysis ,medicine.medical_treatment ,Perineural invasion ,Stage ii ,03 medical and health sciences ,0302 clinical medicine ,Internal medicine ,medicine ,Adjuvant therapy ,Humans ,Neoplasm Invasiveness ,Basal cell ,Aged ,Neoplasm Staging ,Proportional Hazards Models ,Retrospective Studies ,Locoregional failure ,Squamous Cell Carcinoma of Head and Neck ,business.industry ,Wide local excision ,Mouth Mucosa ,Margins of Excision ,030206 dentistry ,General Medicine ,Middle Aged ,Prognosis ,Otorhinolaryngologic Surgical Procedures ,Tongue Neoplasms ,Tumor Burden ,Stage i ii ,Head and Neck Neoplasms ,030220 oncology & carcinogenesis ,Neck Dissection ,Female ,Mouth Neoplasms ,Surgery ,Neoplasm Recurrence, Local ,business - Abstract
Objectives To study the determinants of locoregional control (LRC) on stage I/II oral squamous cell carcinoma (OSCC) classified by AJCC 8th edition. Methods Retrospective analysis from 296 patients of pT1-2N0 oral OSCC treated with surgery (wide local excision and selective neck dissection). Those receiving adjuvant therapy were excluded. Multivariate analysis was performed for impact of adverse pathological features (APFs) on LRC. Results In stage I, LRC was impacted by perineural invasion (PNI) (HR 7.72, p = 0.010, 95% CI 1.64–36.26) and moderate/poor differentiation (MD/PD) (HR 3.04, p = 0.049, 95% CI 0.99–9.25). In stage II, LRC was impacted by depth of invasion (DOI) (HR 1.59, p = 0.014, 95% CI 1.099–2.32), PNI (HR = 2.86, p = 0.005, 95% CI 1.36–5.98). Combined MD/PD and PNI were associated with worse LRC than either feature individually (HR = 4.12, p Conclusion PNI and differentiation accurately predict LRC in AJCC 8th edition classified stage I/II OSCC. PNI was a stronger predictor of locoregional failure than DOI in stage II disease. By incorporating these parameters, we can improve precision in staging of early OSCC and identify potential candidates for treatment escalation to improve outcomes.
- Published
- 2019
33. Detection of Sortase A and Identification of Its Inhibitors by Paramagnetic Nanoparticle-Assisted Nuclear Relaxation
- Author
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Anjaly N. Vijayan, Mary Anne Refaei, Rebecca N Silva, Pearl Tsang, and Peng Zhang
- Subjects
chemistry.chemical_classification ,Staphylococcus aureus ,biology ,Peptide ,medicine.disease_cause ,biology.organism_classification ,Aminoacyltransferases ,Silicon Dioxide ,Virulence factor ,Analytical Chemistry ,Cysteine Endopeptidases ,Enzyme ,chemistry ,Biochemistry ,Bacterial Proteins ,Sortase ,Sortase A ,medicine ,Nanoparticles ,Escherichia coli ,Bacteria - Abstract
Sortase A is a virulence factor responsible for the attachment of surface proteins to Staphylococcus aureus and other Gram-positive bacteria. Inhibitors of this enzyme are potential anti-infective agents. Herein, a new highly selective magnetic relaxation-based method for screening potential sortase A inhibitors is described. A 13-amino acid-long peptide substrate of sortase A is conjugated to SiO2-EDTA-Gd NPs. In the presence of sortase A, the LPXTG motif on the peptide strand is cleaved resulting in a shortened peptide as well as a reduced water T2 value whose magnitude is dependent on the concentration of sortase A. The detection limit is determined to be 76 pM. In contrast, the presence of sortase A inhibitors causes the T2 to remain at a higher value. The proposed method is used to characterize inhibition of sortase A by curcumin and 4-(hydroxymercuri)benzoic acid with an IC50 value of 12.9 ± 1.6 μM and 130 ± 1.76 μM, respectively. Furthermore, this method was successfully applied to detect sortase A activity in bacterial suspensions. The feasibility to screen different inhibitors in Escherichia coli and S. aureus suspensions was demonstrated. This method is fast and potentially useful to rapidly screen possible inhibitors of sortase A in bacterial suspensions, thereby aiding in the development of antibacterial agents targeting Gram-positive bacteria.
- Published
- 2021
34. Effect of shock wave on surface morphology and optical properties of acid phthalate based single crystals
- Author
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Manju Kumari, N. Vijayan, Debabrata Nayak, null Kiran, Pargam Vashishtha, Amit Kumar Gangwar, Govind Gupta, Preetam Singh, and R.P. Pant
- Subjects
Inorganic Chemistry ,Organic Chemistry ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Atomic and Molecular Physics, and Optics ,Spectroscopy ,Electronic, Optical and Magnetic Materials - Published
- 2022
35. Investigation on unidirectionally grown < 010 > potassium acid phthalate single crystal by Sankaranarayanan–Ramasamy (SR) method for optical applications
- Author
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N. Vijayan, J.S. Tawale, Manju Kumari, Kiran, Preetam Singh, Debabrata Nayak, and Rajendra Pant
- Subjects
Diffraction ,Photoluminescence ,Materials science ,Scanning electron microscope ,Potassium ,Analytical chemistry ,chemistry.chemical_element ,Crystal growth ,General Chemistry ,chemistry ,General Materials Science ,Chromaticity ,Luminescence ,Single crystal - Abstract
A bulk size single crystal of Potassium Acid Phthalate was successfully harvested by Sankaranarayanan–Ramasamy method by keeping (010) oriented seed at the bottom. The quality of the grown single crystal was assessed by high-resolution X-ray diffraction technique. The optical quality of the grown single crystal was examined by UV–Vis analysis, which confirms its suitability for nonlinear optical applications. Its luminescence behavior was tested by photoluminescence (PL) and time-resolved PL, respectively. The color coordinates were estimated using the emission spectrum through the CIE chromaticity diagram. The surface morphological pattern was thoroughly studied by scanning electron microscopy (SEM) method.
- Published
- 2021
36. A Review on Rare Calciphylaxis Due to Primary Hyperparathyroidism
- Author
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A. Mohamad Safwan and K. N. Vijayan
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Parathyroidectomy ,Calciphylaxis ,medicine.medical_specialty ,business.industry ,medicine.medical_treatment ,Renal function ,medicine.disease ,Gastroenterology ,Thrombosis ,Sepsis ,Internal medicine ,medicine ,business ,Dialysis ,Primary hyperparathyroidism ,Calcification - Abstract
Calciphylaxis is a rare life-threatening condition characterized by progressive skin ischemia and extremely painful cutaneous necrosis and ulceration due to mural calcification and thrombosis of arterioles and capillaries in the dermis and subcutaneous adipose tissue. Most often this leads to sepsis and multi-organ failure with very high mortality. It is predominantly seen with end-stage renal disease (ESRD) patients who are on dialysis or who recently received a renal transplant. Therefore, it is associated with secondary or tertiary hyperparathyroidism. This entity termed uremic calciphylaxis. A similar rare entity in a patient with normal kidney function termed non-uremic calciphylaxis. Here we review a rare extensive presentation of calciphylaxis due to primary hyperparathyroidism with normal renal function. Calciphylaxis is a catastrophic disease that carries high morbidity and mortality due to sepsis and multi-organ failure A strong clinical suspicion should be kept in any patients with painful necrotic eschar with normal kidney function. Serum calcium and serum Parathyroid hormone should be screened in such cases. Early identification and prompt multi-disciplinary management are mandatory to improve survival.
- Published
- 2021
37. Structural, electrical and optical properties of gamma irradiated methyl para-hydroxy benzoate single crystals
- Author
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Apurva Gupta, Lekha Nair, N. Vijayan, K. Asokan, and M K Raseel Rahman
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010302 applied physics ,Nuclear and High Energy Physics ,3D optical data storage ,Radiation ,Photoluminescence ,Materials science ,business.industry ,Optical communication ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Laser technology ,Optical materials ,0103 physical sciences ,Optoelectronics ,General Materials Science ,Irradiation ,Fourier transform infrared spectroscopy ,0210 nano-technology ,business ,Gamma irradiation - Abstract
Nonlinear optical materials (NLO) have been garnering attention due to their role in optical data storage, optical communication and laser technology. Organic crystals have emerged as an ex...
- Published
- 2019
38. Nanoparticle assisted nuclear relaxation-based oligonucleotide detection
- Author
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Emily Westbrook, Anjaly N. Vijayan, Rebecca N Silva, Peng Zhang, and Zhao Yu
- Subjects
Indoles ,Gadolinium ,Oligonucleotides ,Analytical chemistry ,chemistry.chemical_element ,Nanoparticle ,02 engineering and technology ,Isoindoles ,01 natural sciences ,Biochemistry ,Analytical Chemistry ,chemistry.chemical_compound ,Environmental Chemistry ,A-DNA ,Spectroscopy ,Detection limit ,Molecular Structure ,Oligonucleotide ,010401 analytical chemistry ,Silicon Dioxide ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,chemistry ,Linear range ,Phthalocyanine ,Nanoparticles ,0210 nano-technology ,DNA - Abstract
We present a proof-of-concept “on-off” detection scheme, which uses gadolinium phthalocyanine (GdTcPc)-grafted silica nanoparticles as paramagnetic centers, capable of modifying the transverse relaxation time (T2) of water protons in solution. A DNA strand (as probe) was conjugated to the GdTcPc to act as a recognition element. In the presence of the target DNA, which was complementary to the probe, an increase in the T2 value was detected, with magnitude proportional to the target DNA concentration. The linear range was observed from 30 to 140 nM, with limit of detection of 15 nM. The developed nuclear relaxation-based detection scheme is shown to be a simple, fast and selective method to detect DNA and could be useful in point-of-care diagnostic applications.
- Published
- 2019
39. Evaluation of structural, optical and mechanical behaviour of L-argininium bis(trifluoroacetate) single crystal: An efficient organic material for second harmonic generation applications
- Author
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Mahak Vij, Debashish Sur, Harsh Yadav, S. A. Martin Britto Dhas, Sonia, Budhendra Singh, N. Vijayan, Ravinder Kumar, and Sunil Verma
- Subjects
Materials science ,Young's modulus ,02 engineering and technology ,Crystal structure ,010402 general chemistry ,01 natural sciences ,Nanoindentation ,High-resolution X-Ray diffraction ,Stiffness ,Crystal ,General Materials Science ,Photoacoustic spectroscopy ,Diffractometer ,Birefringence ,Second-harmonic generation ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,0104 chemical sciences ,Damage threshold ,Thermal conductivity ,Thermal effusivity ,Physical chemistry ,Grain boundary ,0210 nano-technology ,Single crystal ,Mechanical strength - Abstract
In the present technologically advanced era, non-linear optical materials especially organic derivatives are in the limelight due to their fast response in electro-optic switches and high nonlinear efficiency. Therefore, with respect to this behaviour, single crystals of L-argininium Bis(trifluoroacetate) (here in after called LABTF) an organic material was grown by slow evaporation solution growth technique. The grown single crystal was subjected to single crystal X-Ray diffractometer to validate its chemical structure and compound formation. The titled compound crystallizes into an asymmetric entity that comprises of one divalent L-argininium cation and two monovalent trifluoroacetic anion. All the intermolecular hydrogen bonds present in the LABTF crystal structure are investigated by 3D molecular Hirshfeld surface analysis and their relative involvements are disintegrated using 2D fingerprint plots. Further, the crystalline perfection assessment was performed using high-resolution X-Ray diffractometer which divulges the absence of structural grain boundaries in the obtained crystal. Thermal transport parameters of the titled compound were measured through Photoacoustic spectroscopy. The shock strength above which the crystal induces damage was found by the shock damage threshold technique. In addition, mechanical property related parameters such as hardness, stiffness and Young's Modulus were evaluated using the nanoindentation technique. These mechanical parameters resolve the reliability of devices and it can be enhanced by improving the crystal quality.
- Published
- 2019
40. Investigation on the key aspects of l-arginine para nitrobenzoate monohydrate single crystal: A non-linear optical material
- Author
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M. S. Jayalakshmy, Sonia, Mahak Vij, Kanika Thukral, N. Vijayan, Rajnikant, Naghma Khan, and D. Haranath
- Subjects
Environmental Engineering ,Materials science ,business.industry ,Band gap ,General Chemical Engineering ,Photoconductivity ,Analytical chemistry ,02 engineering and technology ,General Chemistry ,Dielectric ,021001 nanoscience & nanotechnology ,Biochemistry ,Crystal ,020401 chemical engineering ,Dielectric loss ,0204 chemical engineering ,Photonics ,0210 nano-technology ,business ,Single crystal ,Diffractometer - Abstract
In the contemporary days, non-linear optical materials (NLO) are getting higher attention as per the increasing demand in optical communication and data storage technology. Consequently, they explore various physical properties of the NLO material for their industrial applications. In current report, l-arginine p-nitrobenzoate monohydrate (LANB) single crystals were obtained by adopting slow cooling technique. The structural confirmation of grown single crystal was carried out using single crystal X-Ray diffractometer. Presence of strain within single crystal was deduced using Hall–Williamson relation. Various defects associated within single crystal were assessed using high resolution XRD. Additionally, its crystalline quality was again confirmed by time resolved photoluminescence spectroscopy (TRPL). Using transmission spectra, the cut off wavelength and band gap of the host material was determined to be nearly 420 nm and 2.9 eV respectively. The dielectric property has been recorded by varying the frequency ranging from 50 Hz to 100 kHz. The curve suggests that dielectric loss value is less at high frequency ensures the suitability of crystal in photonics and NLO based devices. The laser damage threshold values were also measured for single and multiple shots. Thermal parameters of the titled compound were calculated using PPE. In photoconductivity measurement, negative photoconductivity has been observed in titled compound. Microhardness studies were also performed on single crystal to explore its mechanical properties.
- Published
- 2019
41. Validation of the eighth edition AJCC staging system in early T1 to T2 oral squamous cell carcinoma
- Author
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Narayana Subramaniam, Ajit Nambiar, Subramania Iyer, Smitha N. Vijayan, Vidhyadharan Sivakumaran, Tsu-Hui Hubert Low, Adharsh Anand, Krishnakumar Thankappan, Deepak Balasubramanian, and Samskruthi Murthy
- Subjects
medicine.medical_specialty ,business.industry ,Treatment outcome ,Cancer ,General Medicine ,Oral cavity ,medicine.disease ,Gastroenterology ,Disease control ,03 medical and health sciences ,0302 clinical medicine ,Oncology ,030220 oncology & carcinogenesis ,Internal medicine ,medicine ,Overall survival ,030211 gastroenterology & hepatology ,Surgery ,Basal cell ,business ,Staging system ,AJCC staging system - Abstract
BACKGROUND To validate the newly proposed American Joint Committee on Cancer (AJCC) eighth edition staging in early T1 and T2 oral cavity cancers and its effect in predicting tumour control. METHODS Retrospective analysis of treatment outcomes of 441 T1 to T2 oral squamous cell carcinoma (OSCC). Overall survival (OS), disease-specific survival (DSS), and tumour control were calculated and compared between the AJCC 7 and 8 staging systems. RESULTS The 5-year OS was 78% and 61% for T1 and T2 tumours, respetively (P
- Published
- 2018
42. Tuning violet to green emission in luminomagnetic Dy,Er co-doped ZnO nanoparticles
- Author
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K. Ravichandran, N. Vijayan, G. Saravanan, R. K. Kalaiezhily, and V. Asvini
- Subjects
Photoluminescence ,Materials science ,Process Chemistry and Technology ,Doping ,Analytical chemistry ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Field emission microscopy ,X-ray photoelectron spectroscopy ,Transmission electron microscopy ,Materials Chemistry ,Ceramics and Composites ,Diffuse reflection ,0210 nano-technology ,High-resolution transmission electron microscopy ,Luminescence - Abstract
This paper discusses the synthesis of undoped ZnO, 2 mol% Dy doped ZnO, 2 mol% Er doped ZnO and 1 mol% Dy,Er co-doped ZnO nanoparticles by simple combustion technique and the characterization of their structural, morphological, magnetic and optical properties by X-ray diffraction (XRD), X-Ray Photoelectron Spectroscopy(XPS), Field Emission Scanning Electron Microscope (FESEM), High Resolution Transmission Electron Microscope (HRTEM), Diffuse Reflectance Spectroscope (DRS), Vibrating Sample Magnetometer (VSM) and Photoluminescence(PL). All samples are of hexagonal wurzite type structure which was found from XRD analysis. The effects of annealing on morphology and luminescence emission wavelengths were noticed in FESEM and PL, respectively. As-prepared sample displayed spherical morphology and annealed co-doped sample showed interwoven hexagonal stacking like morphology. VSM revealed the room temperature ferromagnetism in doped samples. The photoluminescence under the UV and IR excitations was observed in experiment. The as-prepared samples had violet region emission at the 325 nm excitation. The annealed samples had green region emission under the same excitation. Due to the annealing effect, the enhancement of upconversion luminescence intensity in co-doped sample in green (535 nm) and red (665 nm) regions was observed at the 980 nm excitation.
- Published
- 2018
43. Role of adverse pathological features in surgically treated early oral cavity carcinomas with adequate margins and the development of a scoring system to predict local control
- Author
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Adharsh Anand, Smitha N. Vijayan, Chaya Prasad, Samskruthi Murthy, Subramania Iyer, Narayana Subramaniam, Krishnakumar Thankappan, Deepak Balasubramanian, and Tsu-Hui Hubert Low
- Subjects
Adult ,Male ,medicine.medical_specialty ,Scoring system ,Databases, Factual ,Lymphovascular invasion ,medicine.medical_treatment ,Perineural invasion ,India ,Risk Assessment ,Disease-Free Survival ,03 medical and health sciences ,0302 clinical medicine ,Tongue ,Confidence Intervals ,medicine ,Adjuvant therapy ,Humans ,Neoplasm Invasiveness ,030223 otorhinolaryngology ,Pathological ,Aged ,Neoplasm Staging ,Proportional Hazards Models ,Retrospective Studies ,Aged, 80 and over ,Mouth ,business.industry ,Hazard ratio ,Margins of Excision ,Neck dissection ,Middle Aged ,Prognosis ,Survival Analysis ,Tongue Neoplasms ,Early Diagnosis ,Treatment Outcome ,medicine.anatomical_structure ,Otorhinolaryngology ,030220 oncology & carcinogenesis ,Carcinoma, Squamous Cell ,Female ,Radiology ,Neoplasm Recurrence, Local ,business - Abstract
Background The purpose of this study was to determine the factors affecting local control in patients with T1N0 squamous cell carcinoma (SCC) of the tongue. Methods We conducted a retrospective analysis of 144 patients with pT1N0 SCC of the tongue who underwent wide excision and neck dissection without adjuvant therapy. Results The adverse pathological features associated with local control were least margin 5 mm (P = .004), infiltrative margin (P = .403), depth >4 mm (P = .136), lymphovascular invasion (P = .301), and perineural invasion (P = .342). We derived a scoring system of 10 points based on the hazard ratio for local failure; those with scores >5 points had a 5-year local control of Conclusion This study suggests patients having a margin of 5 mm need revision, however, if they do not have additional adverse pathological features (score ≤4), local control is 88% at 5 years, and they may be observed. Those who have margins over 5 mm with a total score >5 may still benefit from adjuvant therapy. Those with margins over 5 mm have improved local control (P = .029).
- Published
- 2018
44. Bulk growth of Iminodiacetic acid single crystal and its characterization for nonlinear optical applications
- Author
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Rajendra Pant, Debabrata Nayak, Mahak Vij, N. Vijayan, Govind Gupta, Manju Kumari, and B. Sridhar
- Subjects
Diffraction ,Materials science ,Photoluminescence ,Analytical chemistry ,Physics::Optics ,02 engineering and technology ,Dielectric ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Two-photon absorption ,0104 chemical sciences ,Crystal ,Wavelength ,Mechanics of Materials ,General Materials Science ,0210 nano-technology ,Absorption (electromagnetic radiation) ,Single crystal - Abstract
A bulk size transparent nonlinear organic single crystal of Iminodiacetic acid was harvested using slow evaporation solution growth technique in controlled atmosphere with a span of 4 weeks. The structural properties of titled crystal were examined by single-crystal X-ray diffraction. The quality of the ingot was determined by high-resolution X-ray diffraction and found that the sample is free from grain boundaries. From UV–Vis analysis, one can understand that there is less absorption in the entire wavelength range of visible region and observed cut-off wavelength is 242 nm. From photoluminescence analysis, the emission of wavelength is identified at 421 nm. Mechanical strength and various parameters like work-hardening coefficient and stiffness constant of ingot was measured using Vickers microhardness test and corresponding experimental data had been explained using distinct theoretical models. The variation measurement of dielectric constant and dielectric loss in respect of frequency was carried out to compute the electronic polarizability of titled compound using Penn model. The detailed analysis of third-harmonic generation was executed using Z-scan method. The values of nonlinear refractive index (n2) and two photon absorption coefficient (β) were obtained to be 2.19 × 10−17 cm2 W−1 and 4.25 × 10−12 cm W−1, respectively. The higher value of coupling factor suggests nonlinear absorption is more dominant and the crystal is suitable for optical limiting application.
- Published
- 2021
45. Investigation on synthesis, growth, Hirshfeld surface and third order nonlinear optical properties of Urea-Succinic Acid single crystal: A potential candidate for self-defocusing lasing application
- Author
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Debabrata Nayak, N. Vijayan, Manju Kumari, null Kiran, Pargam Vashishtha, Subasis Das, B. Sridhar, Govind Gupta, and R.P. Pant
- Subjects
Inorganic Chemistry ,Organic Chemistry ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Atomic and Molecular Physics, and Optics ,Spectroscopy ,Electronic, Optical and Magnetic Materials - Published
- 2022
46. Bharatiya Nirdeshak Dravyas (BND®): Indian Certified Reference Materials
- Author
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Rajendra Pant, N. Vijayan, G. A. Basheed, Dinesh K. Misra, Kuldeep Maurya, Vidya Nand Singh, S. Swarupa Tripathy, Samar Singh, Arvind Gautam, and Nahar Singh
- Subjects
Engineering ,Standardization ,business.industry ,media_common.quotation_subject ,Comparability ,Certification ,Terminology ,Engineering management ,Certified reference materials ,Quality (business) ,business ,Quality assurance ,Reliability (statistics) ,media_common - Abstract
Bharatiya Nirdeshak Dravya (BND®) is the trademark of Certified Reference Material (CRM) of CSIR-NPL. BNDs are the primary standards, which ensure reliability and comparability of the measurements as a benchmark for the quality assurance achieved through international networking. Networking between the NMIs through bilateral cooperation, participation with international bodies/organization establishes wide-ranging recognition of BND in India. BND is the heart of India’s scientific and industrial development by establishing quality control in measurements. A detailed discussion to overcome barriers in international trade and standardization of measurement with high metrological aspect has been emphasized. BNDs are produced by CSIR-NPL: (i) in-house and (ii) in association with Reference Material Producers (RMPs) across the country as per ISO 17034 standard. A detailed emphasis on production of BNDs are given in Chap. 19. The BNDs produced by CSIR-NPL in different sectors are uploaded in the international COMAR database, i.e. COde d'Indexation des Materiaux de Reference (COMAR) for its global visibility. To enhance the impact of reference materials in the global economy, Bureau of Indian Standard (BIS) has recently established national mirror committee on reference materials which is a part of ISO-REMCO (Committee on reference materials). The main aim of this chapter is to make the readers acquainted with process and guidelines who are working in reference standard and looking for certification of their products. This chapter describes the terminology/definition and international networking. The metrological traceability of BNDs established are linked to SI units which have been elaborated in detail. Further, the metrological perspective, such as testing, calibration, method of validation, repeatability, reproducibility studies, control chart preparation, inter-laboratory comparison, quality control and quality assurance are also discussed for a broader readership. A detailed emphasis has been given on international key comparison, proficiency/round-robin testing, pilot study in various sectors like physico-mechanical, physico-chemical, foods/feedstuffs, biomedical, environmental, health-care, agricultural etc. in this chapter.
- Published
- 2020
47. Investigation of micro-indentation hardness of Bi2Te3 based composite thermoelectric materials
- Author
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N. Vijayan, Dinesh K. Misra, Debabrata Nayak, Ashish Kumar, Bal Govind, and Sahiba Bano
- Subjects
Diffraction ,Materials science ,Micro indentation ,Phase (matter) ,Composite number ,Solid-state ,Spark plasma sintering ,Composite material ,Thermoelectric materials ,Characterization (materials science) - Abstract
We have successfully synthesized Bi0.5Sb1.7Te3+x (x = 0, 0.12, 0.14) composite thermoelectric materials via solid state reaction followed by Spark Plasma Sintering (SPS). The structural characterization of these materials carried out by X-ray diffraction reveals to be composite phase consisting of Bi2Te3-type phase with small amount of Te and Sb phase. The micro-hardness performed on samples Bi0.5Sb1.7Te3+x(x =0, 0.12, 0.14) reveals the reduction of VHN with increasing Te concentration as compared to that of single phase state –of-the-art Bi0.5Sb1.5Te3 thermoelectric materials.
- Published
- 2020
48. Bharatiya Nirdeshak Dravyas (BND®): Indian Certified Reference Materials
- Author
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Radha Pant, Nahar Singh, Vidya Nand Singh, S. Swarupa Tripathy, Dinesh K. Misra, Arvind Gautam, N. Vijayan, G. A. Basheed, S. P. Singh, and Kuldeep Maurya
- Subjects
Agricultural science ,Certified reference materials ,Production (economics) ,Environmental science - Published
- 2020
49. Efficient colloidal route to pure phase kesterite Cu 2 ZnSnS 4 (CZTS) nanocrystals with controlled shape and structure
- Author
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Parul Chawla, Shailesh Narain Sharma, N. Vijayan, Shefali Jain, and Dinesh Singh
- Subjects
Materials science ,Band gap ,Nanoparticle ,02 engineering and technology ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,Contact angle ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Nanocrystal ,Phase (matter) ,Nano ,engineering ,General Materials Science ,CZTS ,Kesterite ,Electrical and Electronic Engineering ,0210 nano-technology - Abstract
This work reports the synthesis of varied shaped Cu2ZnSnS4 (CZTS) nano inks in a most stable kesterite phase via a hot injection colloidal route. CZTS nanoparticles of varied shape were synthesized by using various capping ligands with the introduction of butylamine as a new capping ligand and two different sulfur precursors respectively. The shape of the as-synthesized kesterite CZTS nanocrystals can be well controlled in the form of nanofibers, spherical nanoparticles, nano hexagons, nanotriangles, and nanodiscs. A detailed analysis of the effects of various capping ligand and sulfur source on reaction conditions to obtain pure phase kesterite CZTS nanocrystals for different shapes is explained using LaMer's diagram. It has been found that the choice of sulfur precursor also plays an important role in determining the symmetry and orientation of the plane of the CZTS nanocrystals. Due to different morphology and capping ligands present on the surface, diverse surface properties were obtained which was confirmed by contact angle measurements. The variation in the band gap was also found with changes in morphology of kesterite phased CZTS nanoparticles. Due to variations obtained in band gap, changes in I-V characteristics were also observed which may leads different CZTS nanoparticles to have their potential applications in different regime other than photovoltaics like sensors, photocatalysis etc.
- Published
- 2018
50. Time-controlled synthesis mechanism analysis of kesterite-phased Cu2ZnSnS4 nanorods via colloidal route
- Author
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Shefali Jain, Dinesh Singh, N. Vijayan, and Shailesh Narain Sharma
- Subjects
Materials science ,Materials Science (miscellaneous) ,Nucleation ,Nanoparticle ,Nanochemistry ,02 engineering and technology ,engineering.material ,010402 general chemistry ,01 natural sciences ,chemistry.chemical_compound ,Phase (matter) ,Kesterite ,CZTS ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Cell Biology ,021001 nanoscience & nanotechnology ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Chemical engineering ,chemistry ,Nanocrystal ,engineering ,Nanorod ,0210 nano-technology ,Biotechnology - Abstract
In this work, stable Cu2ZnSnS4 (CZTS) nanocrystals (NCs) in pure kesterite phase were synthesized by a facile one-pot rapid injection technique (colloidal route). Time-dependent reaction mechanism for the synthesis of CZTS nanoparticles is explained. When TOP-S (Tri-octyl phosphine–sulphur) was injected in the CuZnSn-complex with TOPO (Tri-octyl phosphine oxide) as capping ligand, orthorhombic phase Cu2−XS nanoparticles of spherical shape were found at nucleation sites. With an advancement in the reaction time, Sn got infused in Cu2−XS to form Cu2SnS3 and its shape got deformed. Further increase in reaction time infuses Zn to form Cu2ZnSnS4 with the gradual vanishing of Cu2−XS and Cu2SnS3 phases and finally, the rod-shaped CZTS Np’s were obtained. This factor of reaction time, which influence the morphology and size were studied in detail. The structural and optical properties of the pure kesterite phase CZTS nanorods were also analysed. The band gap of the rod-like CZTS is determined to be around 1.43 eV, which is an optimum value for solar photoelectric conversion.
- Published
- 2018
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