Synthesis of ultra-high temperature silicon oxycarbide (SiOC) glass by an organic-inorganic hybrid route

Silicon oxycarbide is a new generation amorphous glassy ceramic possessing unique electrical, mechanical, optical properties and ultra-high temperature stability upto 2730°C. It has numerous engineering applications in additive manufacturing, lithium-ion batteries, brake disks for sports car, ultra-fast and high voltage LEDs, MOSFETs, thyristors for high power switching, astronomical telescope, nuclear power reactor etc. In this work, SiOC was prepared by sol-gel technique using organic-inorganic hybrids as precursors. Tetraethoxysilane (TEOS) and Polydimethylsiloxane (PDMS) were used as silica and carbon sources respectively. SiOC sols were formed through hydrolysis of TEOS and PDMS. The used chemicals in this process involved isopropanol, distilled water and hydrochloric acid, which is used here as solvent, hydrolytic agent and catalyst respectively, at different refluxing condition, alkoxide to water ratios, pH levels etc. The sols thus formed were allowed to gel over a varying period (up to maximum of 10 days). After drying the gels for 24 hours, the same was pyrolysed at 1100°C under inert nitrogen atmosphere to yield SiOC. Phase formation was carried out by X-Ray Diffraction (XRD) technique, X-ray Photoelectron Spectroscopy (XPS) analysis and Raman Spectroscopic analysis. XRD data showed formation of a broad peak at 2θ~22 degrees indicating formation of amorphous SiOC and absence of any crystalline peaks indicating no SiC or Si was formed during pyrolysis. XPS data shows the presence of Si, O and C peaks in the range 100-200 eV, 530 eV and 285 eV, respectively, confirming formation of SiOC. It was revealed that within the random network of Si-O tetrahedra, islands of only C-C bonds were responsible for coloring the SiOC glass black. The estimation of mechanical properties revealed that the hardness value and Young’s modulus, of the synthesized SiOC ceramic sample, was determined to be 11.67 GPa and 75.79 respectively which indicating the better mechanical properties than other reported SiOC systems

Contextualizing spatiality of multidimensional poverty in rural and urban India: A geographical perspective

The present study tries to estimate the spatial pattern of incidence, extent and severity of multidimensional poverty in rural and urban India during 2021 obtaining data from the report of NITI Aayog based on NFHS-4 dataset. The study reveals that large interstate disparities persist in the pattern of multidimensional poverty and its intensity in rural and urban India. The study also attempts to examine the interstate deprivation in different indicators of rural and urban MPI which confirms that the magnitude of deprivation is acute in most of the poverty indicators in the poorer states of India like Bihar, Jharkhand, Uttar Pradesh, Madhya Pradesh etc. Finally we have also performed the decomposition analysis to identify the most significant contributor for multidimensional poverty which revealed in both rural and urban space among the dimension health and among the indicators nutrition have made most significant contribution in overall score of multidimensional poverty. The target oriented policy for poverty eradication programmes needs to be stressed. The present study may be beneficial for the development planners and policy makers to understand the pattern of rural and urban multidimensional poverty and deprivation across the states of India in a better way

Thermal degradation of alkyl triphenyl phosphonium intercalated montmorillonites

The decomposition mechanism of intercalated montmorillonites at a particular temperature region and the activation energy involved in it are the two important aspects which determines the thermal stability of intercalated montmorillonites. In this study, montmorillonite was intercalated with alkyl (methyl, ethyl, propyl, and dodecyl) triphenyl phosphonium intercalates. Differential thermogravimetric analysis of each intercalated montmorillonites showed different peaks with associated organic loss at different temperature zone. Intercalated montmorillonites were subjected to isothermal kinetic analysis corresponding to selected temperature zone obtained from DTG peaks. Activation energies of organic decomposition process at selected temperature zones were determined. Mass spectral analysis and FTIR were done to understand the decomposition mechanisms and to relate them with the estimated activation energies

Simultaneous intercalation of two quaternary phosphonium salts into montmorillonite

Intercalation of montmorillonites with a mixture of intercalates has not been studied extensively. The objective of the present investigation was to study the effects of phosphonium-based intercalate mixtures on the properties (organic loading and basal spacing) of montmorillonite. These phosphonium-intercalated montmorillonites are promising candidates as high-temperature stable nanofillers for application in clay polymer nanocomposites. Two salts with different cationic heads and chain lengths were mixed in varying molar ratios and the mixtures were intercalated into the interlayer space of montinorillonite. Two sets were chosen based on the chain length and the cationic head-group structure of the two intercalated salts (referred to hereafter as set 1 and set 2). The resultant intercalated montmorillonite was characterized by thermogravimetric analysis, X-ray diffraction, and transmission electron microscopy. The organic loading of the intercalated montmorillonite increased with the proportion of longer carbon-chain intercalate in the mixture. The intensity of the characteristic XRD peak of each intercalate varied with the mole fraction percent of that intercalate in the solution mixture. No marked synergistic effect of the intercalate mixture on the basal spacing and organic loading properties of the intercalated montmorillonite was observed the proportional influence of individual components was found to be more prominent

Physics based modeling of dust accumulation on a bifacial solar PV module for generation loss estimation due to soiling

In this paper, a physics-based model for dust accumulation on the front and rear surfaces of a bifacial module is presented. The accumulation on both the surfaces is assessed considering deposition, rebound and resuspension phenomena. The lift-off phenomenon of dust particle from ground is included additionally for the rear surface. This composite model is utilized to estimate soiling on both sides, which is extended to analytically assess the energy loss of the bifacial module. Experimentation has been carried out in four phases on a 10 kWp rooftop solar PV power plant. In the first phase, result shows soiling is less on glass than on the transparent back sheet-based rear surface. In the second phase, it is observed that surface density of dust on back surface for 34 days is 0.08 g/m2, for 79 days 0.6 g/m2 and for 126 days 1.8 g/m2 which are deviated from model based calculated ones by 10%, 33.33% and 4.4% respectively. The surface density of dust accumulated on the glass-based rear surface is about (1/6)th of the front glass surface, which is validated by the model also. The measured transmittance reduction is 3.2% for the back glass substrate and 29.6% for the front glass without manual cleaning for the test period. The model leads to the interesting result that the average energy generation loss for the bifacial plant is 1.4%/day compared to 1.7%/day for the monofacial plant since the generation enhancement from the rear surface more than compensates for the soiling loss from the back surface

Hydrophobically Tailored Carbon Dots toward Modulating Microstructure of Reverse Micelle and Amplification of Lipase Catalytic Response

This article delineates the modulation of microstructure of cationic reverse micelle utilizing hydrophobically modified carbon dots (CDs) with varying surface functionalizations. Citric acid was used as the source of the carbon core, and Na-salt of glycine, glycine, Na-salt of 11-amino­undecanoic acid, 11-amino­undecanoic acid, and <i>n</i>-hexadecyl­amine were used for the surface fabrication of CDs to produce CD <b>1s</b>, CD <b>1a</b>, CD <b>2s</b>, CD <b>2a</b>, and CD <b>3</b>, respectively. All these CDs having dimension of 5–7 nm were characterized by spectroscopic and microscopic techniques. The hydrodynamic diameter of cetyl­trimethyl­ammonium bromide (CTAB) reverse micelle (CTAB/isooctane/<i>n</i>-hexanol/water) at <i>z</i> ([cosurfactant]/[surfactant]) = 6.4 and <i>W</i>₀ ([water]/[surfactant]) = 44 is around 15–20 nm. Interestingly, the size of the water-in-oil (w/o) microemulsions dramatically increased up to 120–200 nm upon doping hydrophobic surface functionalized CD <b>2a</b> and CD <b>3</b>. This is possibly due to change in the micellar exchange dynamics and reorganization of the micellar aggregates via hydrophobic interaction between surfactant (CTAB) tail and hydrophobic surface modifier of the carbon dots. However, no alteration in the size of reverse micelles was noted in the presence of carbon dots CD <b>1s</b>, CD <b>1a</b>, and CD <b>2s</b>. Spectroscopic and microscopic investigations confirmed that the hydrophobic CD <b>2a</b> and CD <b>3</b> were localized at the interface of reverse micelles whereas CD <b>1s</b>, CD <b>1a</b>, and CD <b>2s</b> were possibly located in the water pool (away from interface). The activity of <i>Chromobacterium viscosum</i> lipase encapsulated within CD <b>3</b> and CD <b>2a</b> doped significantly large CTAB reverse micelles showed remarkable improvement (3.7-fold and 3.4-fold) in its catalytic response. However, hydrophilic carbon dots CD <b>1s</b> and CD <b>2s</b> as well as moderately hydrophobic CD <b>1a</b> had no significant effect on the microstructure of reverse micelles as well as on the lipase activity

Fluorescent Indicator Displacement Assay: Ultrasensitive Detection of Glutathione and Selective Cancer Cell Imaging

This Research Article reports the development of nanohybrid comprising of anionic carbon dots (ACD) protected gold nanoparticle (GNP). ACD directly cap GNP through its anionic surface functionalization leading to the formation of stable aqueous GNP dispersion. This newly developed ACD-GNP nanohybrid has been thoroughly characterized by different spectroscopic and microscopic techniques. This nanohybrid is successfully employed toward the selective sensing of glutathione (GSH). The mechanism of GSH sensing by this nanosensor is based on the GSH triggered displacement of fluorescent indicator ACD from the GNP surface. Upon capping GNP, intrinsic fluorescence of ACD gets quenched. Addition of GSH displaces the fluorescent indicator ACD from GNP surface and restores the fluorescence signal of ACD. This nanosensor exhibits very high selectivity as well as sensitivity toward glutathione over the other biothiols and can detect as low as 6 nM of GSH. More importantly, selective imaging of the cancer cells over the noncancerous cells was achieved by this ACD-GNP hybrid implying its potential applications in biosensing, as well as in cancer diagnosis

Amino acid functionalized blue and phosphorous-doped green fluorescent carbon dots as bioimaging probe

Amino acid functionalized carbon dots (CDs) were synthesized in a simple and cost effective bottom up approach. Citric acid was used as the source of the carbon core and three amino acids L-isoleucine, L-valine and glycine were used for the surface fabrication of CDs to produce CD<SUB>iso</SUB>, CD<SUB>val</SUB> and CD<SUB>gly</SUB>, respectively. Interestingly these CDs were found to fluoresce with a blue emission. Doping of phosphorus to these CDs (PCDs) tuned the photoemission properties and produced green emitting PCDs. The doping of phosphorous (P) to these CDs improved their fluorescence intensity as well as quantum yields. Both doped and non-doped CDs were characterized by spectroscopic and microscopic techniques. These highly stable CDs were biocompatible in nature and did not exhibit any photobleaching property over a long span of time even under UV exposure. Subsequently, these CDs were exploited as an excellent bioimaging probe. Importantly CDs and PCDs illuminated cells in two completely different spectral regions blue and green, respectively in accordance with their fluorescence spectral behaviour. Hence, amino acid functionalized carbon dots based bioimaging probes with different fluorescence characteristics were developed that are widely applicable for cellular imaging in both blue and green spectral regions