Processing and characterization of egg shell derived nano-hydroxyapatite synthetic bone for Orthopaedic and Arthroscopy implants and substitutes in dentistry.

The present work is focused on the nano-Hydroxyapatite (nHAp) synthesis with two different Indian breed Aseel and Kadaknath eggshells. The alloplast implants were developed through the foam replica method with polyurethane 45-PPI as a porous template. The synthesized nHAp was characterized by Field Emission Scanning Electron Microscopy (FE-SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The FE-SEM images of the nHAp showed the one dimensional clustered nanoparticles and the X-ray diffraction spectrum confirms that the major phase was hydroxyapatite with a small trace of ß-tricalcium phosphate. The maximum compression strength of the sample was 5.49 ± 0.12 MPa which is in the range of the compression strength of human trabecular bone. The thermal and degradability studies results confirmed that these are highly stable and provides necessary a resorption needed for new bone tissue formation. Besides, the antimicrobial activity against tested human microbiome are satisfactory and the cell viability towards MG 63 human osteoblast-like cells provides a potential pathway for developing the nHAp implants for bone tissue engineering.

Novel Nanoarchitectured Cu2Te as a Photocathodes for Photoelectrochemical Water Splitting Applications.

Designing photocathodes with nanostructures has been considered a promising way to improve the photoelectrochemical (PEC) water splitting activity. Cu2Te is one of the promising semiconducting materials for photoelectrochemical water splitting, the performance of Cu2Te photocathodes remains poor. In this work, we report the preparation of Cu2Te nanorods (NRs) and vertical nanosheets (NSs) assembled film on Cu foil through a vapor phase epitaxy (VPE) technique. The obtained nano architectures as photocathodes toward photoelectrochemical (PEC) performance was tested afterwards for the first time. Optimized Cu2Te NRs and NSs photocathodes showed significant photocurrent density up to 0.53 mA cm-2 and excellent stability under illumination. Electrochemical impedance spectroscopy and Mott-Schottky analysis were used to analyze in more detail the performance of Cu2Te NRs and NSs photocathodes. From these analyses, we propose that Cu2Te NRs and NSs photocathodes are potential candidate materials for use in solar water splitting.

Hydroxyapatite Reinforced Polyvinyl Alcohol/Polyvinyl Pyrrolidone Based Hydrogel for Cartilage Replacement.

Polyvinyl alcohol (PVA) and Polyvinyl Pyrrolidone (PVP) hydrogels are desirable biomaterials for soft tissue repair and replacement. However, the bio-inertness and poor cell adhesive potency of the PVA and PVP hinder the wide range of biomedical applications. In the present work, PVA and PVP were blended with a one-dimensional hydroxyapatite nanorod (HNr), and PVA/PVP/HNr composite hydrogel was synthesized by the freeze-thaw process. The developed hydrogels were characterized by Scanning Electron Microscope (SEM). The bio-ceramic nanohydroxyapatite content was optimized, and it was found that reinforcement improves mechanical strength as well as bioactivity. The compression strength values are 2.47 ± 0.73 MPa for the composite having 2 wt% of nanohydroxyapatite. The storage modulus was much higher than the loss modulus, which signifies the elastic dominancy similar to cartilage. Besides, the antimicrobial activity of nanohydroxyapatite reinforced PVA hydrogel towards bacterial species, Escherichia coli (E. Coli), Staphylococcus aureus (S. aureus) was satisfactory, and the in vitro biocompatibility response towards Human Mesenchymal stem cells(hMSC) after 72 h of culture confirms nanohydroxyapatite reinforced PVA/PVP hydrogels are the promising alternatives for next-generation cartilage substitutes.

Neodymium (Nd) based oxide perovskite nanostructures for photocatalytic and photoelectrochemical water splitting functions.

Neodymium (Nd) based perovskite (Nd1-xCoxFeO3) nanostructures were processed to address the rising energy and environment crisis through offering solutions by photocatalytic and photoelectrochemical (PEC) water splitting reactions. The impact of cobalt (Co) ions on the physicochemical properties of Nd-perovskites were studied using X-ray diffraction (XRD), Raman and electron microscopic instruments. The interaction of metal ions was studied in depth via X-ray photoelectron spectroscopy (XPS). Absorption and photoluminescence signals inferred the optical band gap to be lowered and defect states to increase upon Co substitution. Improved photocatalytic efficacy in Nd1-xCoxFeO3 was evaluated by comparative studies using NdFeO3. Secondly, the enhanced conductivities in Nd1-xCoxFeO3 studied via Nyquist plot was found to be advantageous in photoelectrode fabrication for PEC functions. Time-dependent photocurrent density results affirmed the stability in processed devices. Co ions were also inferred to boost the separation of charge carriers effectively. The improved performance in Nd1-xCoxFeO3 nanostructures were well justified to the successful incorporation of Co ions that sway the Nd-O, Co-O and Co-Fe-O bondings and boost the photon absorption and electronic conductivity to facilitate the observed performance.

Microphysical Features of Rain and Rain events during different Seasons over a Tropical Mountain location using an Optical Disdrometer.

In the present study, seven-year-long observations of rain microphysical properties are presented using a ground-based disdrometer located at Braemore; a site on the windward slope of the Western Ghats (WG) over the Indian Peninsula. The annual cycle of rainfall shows a bimodal distribution with a primary peak during summer monsoon and secondary peak during pre-monsoon. Pre-monsoon rain events are less in number but are with high intensity and characterize large raindrops and low number concentration. During summer monsoon, short and less intense rain events with small drops are noticed. Post-monsoon rain is having a long duration less intense events with lower concentration of large raindrops compared to the summer monsoon. In the seasonal variation of mean diameter (Dm) and raindrop concentration (NT) with Rain Intensity (RI), winter and pre-monsoon rains exhibit higher values of Dm and lower values of NT compared to the summer and post-monsoon seasons for all the RI ranges. The mean features of the rain microphysical parameters are also supported by the case studies of rain events. RI, Dm and NT are categorized into different range bins for all the seasons to identify their variation and relative rainfall contribution to the total seasonal rainfall. Heavy drizzle/Light rain has maximum rain duration, and the relative contribution to the rainfall is high from heavy rain type. Winter and pre-monsoon rains are mostly contributed from the larger raindrops (>Dm3), and during summer and post-monsoons it is from Dm2 onwards. The distribution of occurrence frequency of NT and rainfall are similar during all four seasons. NT2 recorded rainfall percentage nearly the same as NT1 in summer monsoon and this also supports large number of raindrops in this season. In RI-Duration analysis, all seasons showed similar distribution, and 90% of total duration is contributed from RI with less than 20 mm h-1.

Arrayed CdTeMicrodots and Their Enhanced Photodetectivity via Piezo-Phototronic Effect.

In this paper, a photodetector based on arrayed CdTe microdots was fabricated on Bi coated transparent conducting indium tin oxide (ITO)/glass substrates. Current-voltage characteristics of these photodetectors revealed an ultrahigh sensitivity under stress (in the form of force through press) while compared to normal condition. The devices exhibited excellent photosensing properties with photoinduced current increasing from 20 to 76 µA cm-2 under stress. Furthermore, the photoresponsivity of the devices also increased under stress from 3.2 × 10-4 A/W to 5.5 × 10-3 A/W at a bias of 5 V. The observed characteristics are attributed to the piezopotential induced change in Schottky barrier height, which actually results from the piezo-phototronic effect. The obtained results also demonstrate the feasibility in realization of a facile and promising CdTe microdots-based photodetector via piezo-phototronic effect.

Evidencing enhanced charge-transfer with superior photocatalytic degradation and photoelectrochemical water splitting in Mg modified few-layered SnS2.

Recently there has been immense interest in the exploration of richly available two-dimensional non-toxic layered material such as tin disulfide (SnS2) for potential employment in energy and environmental needs. In this regard, we report on the synthesis of few-layered Sn1-xMgxS2 nanosheets through a facile one-step hydrothermal route to address all such functions concerning photocatalysis and photoelectrochemical conversion. The crystalline order and structure of processed layered Sn1-xMgxS2 were initially found to exhibit a strong influence on their physicochemical properties. Their optical properties attest the Mg doping in SnS2 to benefit us with enhanced visible-light absorption via red-shift in their absorption edge. In the photoluminescence spectrum the emissions observed along visible and red region signifies the association of Mg related trap states in Sn1-xMgxS2. Next, the photocurrent and electrochemical impedance spectroscopic results revealed the Mg doping to promote the effective charge transfer process (which was beneficial to enhance their photocatalytic activity). Consequently, the layered Sn0.98Mg0.02S2 made photoanodes displayed 1.7 fold higher photocurrent density under simulated solar radiation with respect to their undoped counterpart. Furthermore, the layered Sn0.98Mg0.02S2 nanosheets exhibits enhanced visible light decomposition of organic dye while compared with pristine SnS2 nanosheets. The value of rate constants obtained for the Sn0.98Mg0.02S2 nanosheets was found to be 1.4 times higher than that of pristine SnS2. Finally, the results obtained through the present study projects the huge potential of layered Sn0.98Mg0.02S2 nanosheets for future multifunctional applications.

Ultrasonic-assisted synthesis of ZnTe nanostructures and their structural, electrochemical and photoelectrical properties.

Colloidal zinc telluride (ZnTe) nanostructures were successfully processed through a simple and facile ultrasonic (sonochemical) treatment for photoelectronic applications. The particle-like morphological features, phase and nature of valence state of various metal ions existing in ZnTe were examined using electron and X-ray photoelectron spectroscopic tools. Raman spectroscopic measurements revealed the dominance of exciton-phonon coupling and occurrence of TeO2 traces in ZnTe through the corresponding vibrations. Optical bandgap of the ZnTe suspension was estimated to be around 2.15eV, authenticating the direct allowed transitions. The p-type electrical conductivity and charge carrier density of ZnTe were additionally estimated from the Bode, Nyquist and Mott-Schottky type impedance plots. The photoelectrical properties of ZnTe were investigated by fabricating p-ZnTe/n-Si heterostructures and studying their corresponding current-voltage characteristics under dark and white light illumination. The diodes revealed excellent rectifying behaviour with significant increase in reverse current under illumination. The stability of the devices were also affirmed through the time-dependent photoresponse characteristics, which actually suggested the improved and effective separation of photo generated electron hole pairs across the integrated heterojunctions. The obtained results also augment the potential of sonochemically processed ZnTe for application in photo detection and sensor related functions.

Tunable UV-visible absorption of SnS2 layered quantum dots produced by liquid phase exfoliation.

4H-SnS2 layered crystals synthesized by a hydrothermal method were used to obtain via liquid phase exfoliation quantum dots (QDs), consisting of a single layer (SLQDs) or multiple layers (MLQDs). Systematic downshift of the peaks in the Raman spectra of crystals with a decrease in size was observed. The bandgap of layered QDs, estimated by UV-visible absorption spectroscopy and the tunneling current measurements using graphene probes, increases from 2.25 eV to 3.50 eV with decreasing size. 2-4 nm SLQDs, which are transparent in the visible region, show selective absorption and photosensitivity at wavelengths in the ultraviolet region of the spectrum while larger MLQDs (5-90 nm) exhibit a broad band absorption in the visible spectral region and the photoresponse under white light. The results show that the layered quantum dots obtained by liquid phase exfoliation exhibit well-controlled and regulated bandgap absorption in a wide tunable wavelength range. These novel layered quantum dots prepared using an inexpensive method of exfoliation and deposition from solution onto various substrates at room temperature can be used to create highly efficient visible-blind ultraviolet photodetectors and multiple bandgap solar cells.

Vertically aligned ZnCdS nanowire arrays/P3HT heterojunctions for solar cell applications.

Nowadays, solid-state inorganic-organic hybrid solar cells based on one-dimensional (1D) inorganic semiconducting nanostructures and organic polymers are believed to offer convincing solutions for the realm of next generation solar cells. In this regard, 1D ZnCdS nanowire (NW) arrays were fabricated on transparent conducting substrates through a catalyst free co-evaporation method and their wurtzite structural characteristics, 1D morphological layout and valence state/composition were studied in detail using X-ray diffraction, high-resolution electron microscopy and X-ray photoelectron spectroscopy, respectively. The existence of deep level traps and optical band gap of ZnCdS NWs were additionally studied using room-temperature cathodoluminescence and UV-vis absorbance measurements. The inorganic-organic hybrid cells were then fabricated using these NWs via spin coating poly(3,4-ethylenedioxythiophene) and poly(styrene sulfonate) based polymers. The morphological dissemination of the polymer deposits on NWs were also studied individually by electron microscopy. The solar cell (J-V) characteristics of the fabricated architectures were investigated at room-temperature and as a function of temperature and different intensities of incident light irradiation. The trap energy of the devices was noted to decrease from 68.1 to 40.7eV, suggesting the active role of trap sites that could have originated from the surface defects and other structural disorders across the hybrid heterostructures.

Colloidal synthesis and electrical behaviour of n-ZnGdO/p-Si heterojunction diodes.

Studies on manoeuvring the optoelectronic characteristics of a semiconducting nanostructure are of recent specific interest for a wide range of photonic applications. In this regard, the optical and electrical characteristics of ZnO nanostructures have been tuned and studied systematically using Gd ions. The structural and morphological characteristics of the solution processed ZnGdO nanostructures were studied in detail using the results of X-ray diffraction and microscopic measurements. The absorption band edge in ZnO was noted to shift towards the lower wavelength values on Gd substitution, suggesting an increase in its energy band gap. The blue emissivity from ZnO complexes was also noted to improve as a function of Gd composition in ZnO. The potential of ZnGdO nanostructures for optoelectronic functions was evaluated by fabricating heterojunction diodes based on n-ZnGdO/p-Si. The diode characteristics revealed an improved electrical conductivity and rectifying behaviour from the fabricated architectures upon Gd substitution and photon illumination. The findings are correlated with the increased charge carrier concentration and defect states existing within ZnGdO species, through appropriate mechanisms.

Solution processed n-In2O3 nanostructures for organic-inorganic hybrid p-n junctions.

Solution processed organic-inorganic bulk hybrid heterostructures are nowadays considered as the most promising elements to perform efficient optoelectronic functions. In this regard, In2O3 based hybrid heterostructures were fabricated using polypyrrole and their role as efficient interfacial layers was studied using polypyrrole/ZnO nanowires. The In2O3 nanostructures were synthesized through a facile wet chemical approach at an average scale of less than 10 nm in cubic phase. The presence of O and In related defects was studied through emission spectra; these were also found to exhibit their predominance in Raman measurements. The n-type characteristics and donor density value of around 10(20) cm(-3) were evaluated for the In2O3 specimens via Mott-Schottky plots. The role of In2O3 nanostructures as active/interfacial layers was then studied using the current-voltage characteristics obtained across the hybrid heterostructures made of polypyrrole/In2O3, polypyrrole/ZnO and polypyrrole/In2O3/ZnO. Organic-inorganic p-n diodes were obtained via in situ chemical polymerization, drop casting and hydrothermal routes. Cyclic voltammograms and Nyquist plots were used to study the reduction mechanism taking place in the nanostructures that actually results with the formation of metallic In, which plays a vital role in establishing the required conduction electrons. The same has been reasoned for the improved rectification characteristics observed across the diodes.

Structural and optical property studies on indium doped ZnO nanostructures for solution based organic-inorganic hybrid p-n junctions.

In doped ZnO nanocrystallites have established through a facile, low cost and high yield wet-chemical route. The X-ray diffraction measurements revealed the samples to be well crystallized, with a considerable shift in the prominent peak positions, indicating the successful substitution of In ions into the ZnO matrix. The particulate characteristic of the nanostructures was evaluated through the aid of electron microscopes, which revealed both the pristine and In doped ZnO nanocrystals to possess similar morphologies. The UV-vis absorption spectroscopic measurements revealed the doping of In(3+) ions to lead with a red shift in the absorption edge of ZnO nanostructures. The Raman measurements provided conclusive evidence for the substitution of In ions at the Zn sites and their influence on the hexagonal lattice. The hybrid heterostructures made up of polypyrrole/ZnO and polypyrrole/Zn(1-x)In(x)O were established via drop casting a colloidal dispersion containing the prepared nanocrystallites and subsequently chemically in situ polymerizing the pyrrole monomers on the drop casted electrodes. The hybrid p-n junctions were then evaluated using the current-voltage characteristics.

Fabrication of polypyrrole/ZnCoO nanohybrid systems for solar cell applications.

Hybrid solar cells employing conjugated polymers have revolutionized the photovoltaic industry by offering the prospect for large-scale energy conversion applications through cost-effective fabrication techniques. In this regard, we have demonstrated an experimental approach to fabricate polypyrrole/ZnCoO nanorod hybrid systems, using hydrothermal and electropolymerization techniques. The structural property studies on the hydrothermally synthesized Co-doped ZnO nanocrystallites revealed them to be phase pure with rod-like morphology. Considering the significant enhancement in their absorbance values over the visible spectral range (possibility for extended photon absorption), ZnCoO (Zn(0.95)Co(0.05)O) nanorods were deposited on transparent conducting (FTO) substrates through dip-coating methodology, for the fabrication of working electrodes. Electropolymerization of the pyrrole monomers was then carried out on the fabricated electrodes through cyclic voltammetry. The formation of polymer material was verified using FT-IR spectroscopy. The morphological evolution of polypyrrole deposits and their distribution on the working electrodes were substantially studied using atomic force microscopy and scanning electron microscopy. The flat band potential for the hybrid systems assimilated from the Mott-Schottky plots was observed to shift towards negative direction compared with ZnCoO, presumably due to the presence of the polymer composites, which gives rise to a more negative potential.

Developmentally linked changes in proteases and protease inhibitors suggest a role for potato multicystatin in regulating protein content of potato tubers.

The soluble protein fraction of fully developed potato (Solanum tuberosum L.) tubers is dominated by patatin, a 40 kD storage glycoprotein, and protease inhibitors. Potato multicystatin (PMC) is a multidomain Cys-type protease inhibitor. PMC effectively inhibits degradation of patatin by tuber proteases in vitro. Herein we show that changes in PMC, patatin concentration, activities of various proteases, and their gene expression are temporally linked during tuber development, providing evidence that PMC has a role in regulating tuber protein content in vivo. PMC was barely detectable in non-tuberized stolons. PMC transcript levels increased progressively during tuberization, concomitant with a 40-fold increase in PMC concentration (protein basis) as tubers developed to 10 g fresh wt. Further increases in PMC were comparatively modest (3.7-fold) as tubers developed to full maturity (250 g). Protease activity declined precipitously as PMC levels increased during tuberization. Proteolytic activity was highest in non-tuberized stolons and fell substantially through the 10-g fresh wt stage. Cys-type proteases dominated the pre-tuberization and earliest stages of tuber development. Increases in patatin transcript levels during tuberization were accompanied by a notable lag in patatin accumulation. Patatin did not begin to accumulate substantially on a protein basis until tubers had reached the 10-g stage, wherein protease activity had been inhibited by approximately 60%. These results indicate that a threshold level of PMC (ca. 3 microg tuber(-1), 144 ng mg(-1) protein) is needed to favor patatin accumulation. Collectively, these results are consistent with a role for PMC in facilitating the accumulation of proteins in developing tubers by inhibiting Cys-type proteases.