Polyaniline/(Ta2O5-SnO2) hybrid nanocomposite for efficient room temperature CO gas sensing.

Development of efficient CO sensors that can detect low concentration CO at room temperature is of prime importance. Herein, we present a Ta2O5-SnO2-PANI hybrid composite for the efficient sensing of CO at room temperature and at very low concentrations. The material was synthesized by the oxidative polymerization method. The structural and morphological characteristics of the nanostructured (Ta2O5-SnO2)-PANI hybrid composite were examined using p-XRD and FESEM techniques. The oxygen vacancies in the material were confirmed by XPS analysis. The hybrid material exhibited superior CO sensing performance with high sensitivity, low operating temperature, and fast response and recovery time compared to the individual counterparts. The enhanced sensing ability of the hybrid material is accredited to the synergistic properties such as conductivity of PANI, improved oxygen vacancies and the heterostructure formed between the PANI and the (Ta2O5-SnO2) composite. These remarkable features make TaSn : PANI a potential sensor at room temperature for sensing of low concentration CO.

Scheelite like NaTb(WO4)2 nanoparticles: Green fluorescence and in vitro cell imaging applications.

This study highlights the investigation of the green fluorescence in NaTb(WO4)2 materials (NaTbW Bulk and NaTbW Nano) synthesized via template free hydrothermal method as a function of particle size and morphology. Herein, we demonstrated the biocompatibility and intracellular green fluorescence of NaTbW Nano samples using HeLa cells for cell imaging applications. Powder X-ray diffraction studies showed that the as synthesized NaTbW Bulk and NaTbW Nano crystallize in the Scheelite like tetragonal crystal system with the I41/a space group. The reaction pH and solvent is observed to play a critical role in determining particle size, shape and morphology of these luminescent materials. Furthermore, size dependent optical properties were systematically studied by diffuse reflectance, steady state photoluminescence; time resolved fluorescence lifetime and quantum yield measurements. Both the materials have shown bright green fluorescence upon UV excitation as a function of particle size. Remarkable high quantum yield of NaTbW Bulk indicated its greater luminescence efficiency and the closer CIE coordinates to the commercial green illuminant suggested their potential use in solid state display systems. On the other hand the observed biocompatibility of NaTbW Nano particles towards mammalian cancer HeLa cells, Staphylococcus aureus, Escherichia coli and the intracellular green fluorescence rightly proved its functionality as active bio-probes. Thus, our work summarize the potential use of these Scheelite like NaTb(WO4)2 material for solid state display and bio-imaging applications.

An amine functionalized zirconium metal-organic framework as an effective chemiresistive sensor for acidic gases.

Pore surface functionalization of a metal-organic framework (MOF) with an amine moiety has turned an innocent MOF into a chemiresistive sensor for acidic gases. The Zr-NH2-benzenedicarboxylate MOF (NH2-UiO-66) proved to perform as an efficient and stable chemiresistive sensor for SO2, NO2 and CO2 at low concentrations and an operating temperature of 150 °C.

Impact of Average, Local, and Electronic Structure on Visible Light Photocatalysis in Novel BiREWO6 (RE = Eu and Tb) Nanomaterials.

Crystal structures of hydrothermally synthesized BiEuWO6 and BiTbWO6 nanomaterials are deduced for the first time by combined Rietveld refinement of neutron and synchrotron data using the ordered and disordered models available in literature. The ordered model is validated for the average structure of these nanomaterials, and it is further supported by the local structure analysis using neutron pair distribution function. Nanomaterials are characterized by field-emission scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett-Teller surface area, diffused reflectance spectroscopy, and Raman Spectroscopy. Rare-earth-substituted nanomaterials are found to be efficient photocatalysts over the parent Bi2WO6 under visible light irradiation for Congo-red dye degradation. Particularly, BiTbWO6 shows an enhanced photocatalytic (PC) activity compared to BiEuWO6, as evidenced from the photoelectrochemical and time-resolved fluorescence studies. The difference in the observed PC activity of these nanomaterials is also explored through a detailed comparison of crystal structure and electronic structure calculated through the density functional theory method.

Assembly of ZIF-67 Metal-Organic Framework over Tin Oxide Nanoparticles for Synergistic Chemiresistive CO2 Gas Sensing.

Metal-organic frameworks (MOFs) are widely known for their record storage capacities of small gas molecules (H2 , CO2 , and CH4 ). Assembly of such porous materials onto well-known chemiresistive gas sensing elements such as SnO2 could be an attractive prospect to achieve novel sensing properties as this affects the surface chemistry of SnO2 . Cobalt-imidazole based ZIF-67 MOF was grown onto preformed SnO2 nanoparticles to realize core-shell like architecture and explored for greenhouse gas CO2 sensing. CO2 sensing over SnO2 is a challenge because its interaction with SnO2 surface is minimal. The ZIF-67 coating over SnO2 improved the response of SnO2 up to 12-fold (for 50 % CO2 ). The SnO2 @ZIF-67 also showed a response of 16.5±2.1 % for 5000 ppm CO2 (threshold limit value (TLV)) at 205 °C, one of the best values reported for a SnO2 -based sensor. The observed novel CO2 sensing characteristics are assigned to electronic structure changes at the interface of ZIF-67 and SnO2 .

High Surface Area SnO2 -Ta2 O5 Composite for Visible Light-driven Photocatalytic Degradation of an Organic Dye.

SnO2 -Ta2 O5 nanocomposite was synthesized by a facile coprecipitation method and further calcined to obtain crystalline powder. Phase formation, morphology, bandgap and photocatalytic properties were analyzed using powder X-ray diffraction, scanning electron microscopy, UV-Vis diffused reflectance spectroscopy, BET surface area and Raman spectroscopy, respectively. Effect of calcination temperature on the crystallinity of the composite was studied. The as-prepared samples of SnO2 , Ta2 O5 and SnO2 -10wt%Ta2 O5 composite as well as the calcined composite sample were tested for photocatalytic activity for methylene blue dye degradation under visible light. Photocatalytic studies reveal that the as-prepared SnO2 -10wt%Ta2 O5 composite showed the best photocatalytic activity for the degradation of methylene blue (MB) by harvesting visible-light radiation efficiently. Further mineralization of methylene blue, estimated by COD analysis, is found to have degraded with an efficiency of 91.6%. The study demonstrates that heterostructure of SnO2 -Ta2 O5 nanocomposite could be applied in photocatalytic purification of organic pollutants.

Bi4TaO8Cl Nano-Photocatalyst: Influence of Local, Average, and Band Structure.

The average structure, local structure, and band structure of nanoparticles of photocatalyst Bi4TaO8Cl, an Aurivillius-Sillen layered material, has been studied by powder neutron Rietveld refinement, neutron pair distribution function technique, Raman scattering, and density functional theory calculations. A significant local structural deviation of nano-Bi4TaO8Cl was established in contrast to the local structure of bulk-Bi4TaO8Cl. Local structure was further supported by Raman scattering measurements. Through DFT calculations, we identify specific features in the electronic band structure that correlate lower secondary structural distortions in nano-Bi4TaO8Cl. Increased distortion of TaO6, decreased Ta-O-Ta bond angle, and increased octahedral tilt in the local structure of nano-Bi4TaO8Cl influence the band structure and the electron hole pair migration. Therefore, in addition to morphology and size, the local structure of a nanomaterial contributes to the photocatalytic performance. Trapping experiments confirm the role of superoxide radical in the photocatalysis mechanism of this material. Such studies help in developing new functional materials with better photocatalytic efficiency to address energy and environmental issues.

Investigation of Ca substitution on the gas sensing potential of LaFeO3 nanoparticles towards low concentration SO2 gas.

The present work investigates the superior ability of LaFeO3 (LaFeO) and La0.8Ca0.2FeO2.95 (LaCaFeO) nanoparticles to detect 3 ppm SO2 gas. The influence of calcium substitution on the sensing behaviour of LaFeO has been studied. High resolution TEM images show that the particle sizes of LaFeO and LaCaFeO are less than 100 nm and SEM images show the agglomeration of interconnected nanoparticles. Both LaFeO and LaCaFeO crystallize in the orthorhombic crystal system with the space group Pbnm. Rietveld analysis of neutron diffraction data showed that LaCaFeO has lattice oxygen vacancies. In addition, magnetic refinements on both the samples have been carried out. The presence of lattice oxygen vacancies in LaCaFeO is qualitatively supported by Raman and XPS measurements. Electrical characterization showed increased conductivity for the LaCaFeO sample, influencing their sensing performance significantly. The LaCaFeO nanoparticles exhibit higher sensitivity, faster response time, rapid recovery time and good recyclability for sensing 3 ppm SO2 gas. This enhanced sensing behaviour is attributed to the increased oxygen vacancies in the lattice as well as the surface. As a consequence, increased active sites are created in LaCaFeO, promoting redox reaction between the analyte and the sensing material. The results demonstrated that while LaFeO is a good gas sensor, p-type substitution by Ca(2+) renders this material an improved resistivity based gas sensor to detect low concentration SO2.

Metronomic Chemotherapy: Seems Prowess to Battle against Cancer in Current Scenario.

INTRODUCTION: Metronomic chemotherapy is an emerging method of chemotherapy. Metronomic 'lowdose' chemotherapy regimen induces tumour dormancy and reduces cancer resistance against anticancer drugs. It tends to improve overall success rate of cancer chemotherapy than conventional cyclical regimen. AIM: The aim of this systemic review was to provide comprehensive data of metronomic chemotherapy trials, regimens used and it's outcome in cancer therapeutics. MATERIALS AND METHODS: Fifty chemotherapy trial data were searched sequentially from web. The main sources were official website of Clinical trial forum, USA and Clinical Trial Registry India (CTRI). Evidence on efficacy and safety of such metronomic chemotherapy trials was gathered from various data published in Medline, New England Journal of Medicine (NEJM), Lancet Oncology and other journals with high credentials. As a result of our search, out of 50 trials including breast -15(30%), colon-, 5(10%) ovarian -5(10%), prostate-5(10%) and others including haematologic, soft tissue and nervous system malignancies -20 (50%). Twenty seven trials showed favourable, 20 trials showed equivocal outcome and 3 trials reported unfavourable outcome. Overall comparison showed definitive statistical significance for using metronomic regimen (p-0.05). CONCLUSION: It can be concluded that metronomic chemotherapy regimen seems convincing beneficial to induce tumour remission and survival at a higher than conventional regimen. More metanalyses are needed to frame common metronomic chemotherapeutic regimen.

Photoluminescence tuning of Na1-xKxNdW2O8 (0.0 ≤ x ≤ 0.7) nanoparticles: synthesis, crystal structure and Raman study.

A series of Na1-xKxNdW2O8 (0.0 ≤ x ≤ 0.7) nanoparticles have been synthesized by an efficient glycothermal technique for the first time. SEM measurements confirmed the particle size ranges from 30-200 nm with ellipsoidal shaped morphology. Combined X-ray and neutron diffraction and Raman spectroscopy techniques were utilized in order to investigate the influence of K(+) ion substitution in NaNdW2O8. K(+) ion substitution in the crystal lattice introduced a change in the Nd-O bond length and the Nd-O-W bond angle of NaNdW2O8. The photoluminescence intensity increased up to the threshold composition x = 0.4. K(+) ion substitution resulted in blue shifted emission of NaNdW2O8. Size mismatch, the Nd-O-W angle and local disorder contributed to the observed difference in luminescence properties. Also, the chromaticity diagram for this blue emitting phosphor showed the possibility of tuning the emission by incorporation of K.

Neuroprotective effect of Rhodiola rosea Linn against MPTP induced cognitive impairment and oxidative stress.

BACKGROUND: Ageing and age-related neurodegenerative changes including Parkinson's disease are characterized by an important role of reactive oxygen species. It is characterized by signs of major oxidative stress and mitochondrial damage in the pars compacta of substantia nigra. PURPOSE: Present study was designed to investigate whether Rhodiola rosea extract would prevent MPTP induced neurotoxicity in Male wistar rats. METHODS: Male Wistar rats were divided into following five groups: Group I received vehicle (saline (10 ml/kg for 21 days) orally); Group II received Rhodiola rosea extract (250 mg/kg for 21 days) orally; Group III was treated with 20 mg/kg MPTP i.p. for 21 days; Group IV received 20 mg/kg MPTP, i.p. along with 100 mg/kg Rhodiola rosea orally for 21 days. Group V received 20 mg/kg MPTP i.p. along with 250 mg/kg Rhodiola rosea orally for 21 days. RESULTS: MPTP induced rats showed behavioral alterations in elevated plus maze testing. Group III rats elicited significant increase in lipid hydroperoxide along with reduction in level of glutathione peroxidase, catalase, superoxide dismutase and total antioxidants. Histological evidence revealed that MPTP treated rats shown pathological changes like cellular inflammation and vascular degeneration in brain tissue. CONCLUSION: The oxidative stress and related biochemical alteration by MPTP were attenuated by Rhodiola rosea treatment. However, further studies may be necessary to elucidate the precise mechanism to support the clinical use of a plant source as antiparkinsonism drug.

Inhibition of CCl4-induced liver fibrosis by Piper longum Linn.?

This study was carried out to evaluate the antifibrotic effect of ethanol extract of the fruits of Indian herb Piper longum Linn. Liver fibrosis was induced in rats by CCl(4) administration. The extent of liver fibrosis was assessed by measuring the level of liver hydroxy proline (HP) and serum enzyme levels. Following CCl(4) administration HP was significantly increased and serum enzyme levels were elevated. Treatment with the ethanol extract of Piper longum Linn. reduced the HP and also the serum enzymes. The liver weight that increased following CCl(4) administration due to the deposition of collagen was reduced by the ethanol extract. Hence, it is concluded that this extract inhibits liver fibrosis induced by CCl(4).

Oxidative stress in alcoholic liver disease.

We report on the prooxidant (lipid peroxides) and antioxidant levels (ascorbic acid, reduced glutathione, superoxide dismutate activity) in healthy individuals (30) and patients with cirrhosis (37; 22 alcoholic cirrhosis and 15 non alcoholic cirrhosis). A significant increase in plasma lipid peroxide (P < 0.05) and ascorbic acid (P < 0.01) and a significant decrease in reduced glutathione (P < 0.001) and superoxide dismutase activity (P < 0.05) in haemolysate was observed in cirrhosis patients compared to the control group. A significant decrease in reduced glutathione (P < 0.01) and superoxide dismutase (P < 0.05) activity was also observed when the alcoholic cirrhosis group was compared to non alcoholic group. A significant increase in aspartate transaminase (P < 0.05), gamma glutamyl transaminase (P < 0.01) and aspartate transaminase/alanine transaminase (P < 0.05) ratio was seen in alcoholic cirrhosis group. A significant positive correlation between gamma glutamyl transferase and lipid peroxides (r = 0.48, P < 0.05) was observed in alcoholic cirrhosis.