Optical and electrical transport properties of polyaniline–silver nanocomposite

Polyaniline–silver nanocomposite has been synthesized successfully by the chemical oxidative polymerization of aniline with ammonium peroxydisulphate as an initiator in presence of negatively charged silver nanoparticles. Silver nanoparticles are prepared by standard citrate reduction method. TEM, SEM, XRD, FTIR, TGA, DSC, optical absorption and photoluminescence studies are done for the morphological, structural, thermal and optical characterization of the polyaniline nanocomposite. From the TEM and SEM image, it is observed that nanoparticles are well dispersed in the polyaniline matrix. XRD pattern shows that polyaniline is amorphous, but peaks present in XRD pattern in polymer nanocomposites are for silver nanoparticles. TGA and DSC results show that polyaniline silver nanocomposite is more crystalline and more thermally stable. A surface plasmon absorption band is obtained from the optical absorption at 380 nm, which indicates that silver nanoparticles are present in the polyaniline matrix. The optical band gap of nanocomposite decreases with increasing content of silver nanoparticles. An enhancement in photoluminescence has been observed in polyaniline–silver nanocomposite than that in pure polyaniline. The electrical conductivity of polyaniline–silver nanocomposite increases with increase in silver nanoparticle content than that of pure polyaniline. This is a simple way by which optical and electrical properties of polyaniline may be enhanced by doping with suitable nanoparticles.     

A comparative evaluation of household preferences for solar photovoltaic standalone and mini-grid system: An empirical study in a costal village of Indian Sundarban

Solar PhotoVoltaic (SPV) based systems have been widely accepted technology for rural electrification in developing countries. The standalone SPV home lighting system has increasingly been popular among rural households, while SPV mini-grid supply system is being promoted for rural electrification schemes. This study uses data from household survey to explore the impact of household characteristics on the preference for electrical energy from SPV systems. Econometric evidence shows heterogeneity in behavioural pattern for these two SPV systems. The flexibility in use and cost of systems might explain this difference. Household characteristics such as monthly household income, household size, occupational status of household head, number of room and type of house significantly influence household’s decision for SPV standalone home lighting systems. For SPV mini-grid supply household’s income and monthly expenditure on kerosene are significant predictors. The result reported in this paper might be a valuable input for policy makers to frame right policy mix with regard to provide subsidy on rural electrification programmes.     

Cerium-based phosphors: blue luminescent properties for applications in optical displays

In this paper, we describe the blue photoluminescence (PL) observed in the multi-component oxosalt phosphor GdVO₄:Ce³⁺. Different doping concentrations (0.25–1 mol%) and heat treatment (900–1100 °C) were used to evaluate which conditions would lead to the most suitable blue phosphor for optimal display performance. The cerium doping concentration influences the profile of the emission spectrum (broad peak at 412 nm under UV excitation at 330 nm), as reflected on the values of chromaticity coordinates. On the basis of luminescent properties, we can conclude that, among the phosphors prepared in this work the most adequate for a blue display is the one obtained via the combustion method using glycine as fuel, a 0.50 mol% cerium doping concentration, and heat treatment at 1000 °C.     

Phosphate and phosphatase distribution in sediment depths of rockphosphate treated carp culture system

Distribution pattern of phosphates (A1-P, Ca-P, Fe-P), available-P, citrate soluble-P and phosphatases (acid and alkaline) was examined in three sediment layers (0–2.5 cm, 2.6–5.0 cm, 5.1–7.5 cm) of carp (Cirrhinus mrigala) culture system fertilized with varying levels (43.66 kg and 87.32 kg P) and frequencies (7, 15 and 30 days) of rock phosphate. Whereas layer differences of phosphate and phosphatases were significant in any of the treatments employed, significant treatment differences were restricted to first and second layer, but not in third layer implying that uppermost layer was the most active site of treatment action. Large variations in fish yield among six treatments were directly related with P-content of surface sediments, and hence P-level of overlying water. The variations of alkaline phosphatases in the first layer of sediment in each treatment was strongly influenced by Al-P (99.78%), available-P (0.16%) and Fe-P(0.05%), whereas the variations in second layer was mainly affected by Al-P (99.02%). None of these factors were related to the small variations of alkaline phosphatase in third layer of sediment.     

19F and 31P NMR spectroscopy of calcium apatites

Glass ceramics that include apatite crystals are used as implant materials. Because most of these glass ceramics are comprised of fluoride-containing glass compositions, the included apatites could be hydroxyapatite, fluorapatite or fluoride-substituted hydroxyapatite. However, these apatites differ in regard to their solubility and thermal stability. The purpose of the current study was to determine the possibilities of distinguishing between these apatities. High resolution solid-state ¹⁹F and ³¹P magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectra of two fluorapatites, a hydroxyapatite and a fluoridated hydroxyapatite have been obtained. Using ³¹P NMR investigations it is possible to distinguish between calcium apatites and other calcium phosphates, but the distinction between fluoride-containing apatite and hydroxyapatite is not possible. However, ¹⁹F high-resolution solid-state NMR investigations permit the distinction between these various apatites. The results of the NMR investigations could be used for the characterization of glass ceramics. The application of those results was demonstrated using a newly developed apatite-containing glass ceramic.     

Testing a tripartite model: II. Exploring the symptom structure of anxiety and depression in student, adult, and patient samples.

L. A. Clark and D. Watson (1991) proposed a tripartite model of depression and anxiety that divides symptoms into 3 groups: symptoms of general distress that are largely nonspecific, manifestations of anhedonia and low positive affect that are specific to depression, and symptoms of somatic arousal that are relatively unique to anxiety. This model was tested by conducting separate factor analyses of the 90 items in the Mood and Anxiety Symptom Questionnaire (D. Watson & L. A. Clark, 1991) in 5 samples (3 student, 1 adult, 1 patient). The same 3 factors (General Distress, Anhedonia vs. Positive Affect, Somatic Anxiety) emerged in each data set, suggesting that the symptom structure in this domain is highly convergent across diverse samples. Moreover, these factors broadly corresponded to the symptom groups proposed by the tripartite model. Inspection of the individual item loadings suggested some refinements to the model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Determination of aryloxyphenoxypropanoic acid derivatives in crops treated with herbicidal sprays

Summary A reproducible and sensitive gas Chromatographic method has been developed for the trace analysis of fluazifop-butyl, haloxyfop-ethoxyethyl and quizalofop-ethyl as well as their main metabolites (corresponding acids analysed after conversion to methyl esters) in some fruits and vegetables treated with herbicidal sprays. Comparable detection limits (0.01 mg/kg) were achieved when mass fragmentography and/or the electron capture detector were employed. However, in the latter case, bromination of fluazifop esters had to be carried out prior to GC analysis. By means of the nitrogen-phosphorus detector, determination of residues at a level of 0.05 mg/kg was possible. The residue values found in strawberries, cabbages, cauliflowers and carrots were used to discuss the degree of metabolic hydrolysis of parent esters, i.e. active ingredients of herbicides.

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Bestimmung von Aryloxyphenoxypropionsäure-Derivaten in mit Herbicidsprays behandelten Produkten

Zusammenfassung Es wurde eine gaschromatographische Methode zur quantitativen und selektiven Bestimmung von Fluazifop-butyl, Haloxyfop-ethoxyethyl und Quizalofop-ethyl sowie von ihren Hauptmetaboliten (den entsprechenden Säuren, die zu Methylestern umgesetzt werden müssen) in mit Herbiciden behandelten Obst- und Gemüseproben entwickelt. Eine Nachweisgrenze von 0,01 mg/kg wurde durch Elektroneneinfanggaschromatographie oder durch Massenfragmentographie erzielt. Um die gleiche Empfindlichkeit des EC-Detektors bei Fluazifop zu erreichen, wurden die beiden Ester mit Brom umgesetzt. Mit Hilfe des NP-Detektors konnte eine Nachweisgrenze von 0,05 mg/kg erreicht werden. Die festgestellten Rückstandsgehalte in Erdbeeren, Kohl, Blumenkohl und Möhren wurden gleichzeitig zur Beurteilung der metabolischen Hydrolyse der diskutierten Ester (der Wirkstoffe der Herbicide) herangezogen.

     

Promotion of microcrystallization by argon in moderately hydrogen diluted silane plasma

Using argon as a diluent of SiH₄, undoped hydrogenated microcrystalline silicon (μc-Si:H) films, having σ_D10⁻⁵ S cm⁻¹, were prepared at a very high deposition rate of 36 Å/min. Micrograins were identified with several well-defined crystallographic orientations. The effect of variation of Ar-dilution on the electrical and structural properties of Si:H films were studied systematically. Addition of H₂ to the Ar-diluted SiH₄ plasma improved the network structure by eliminating defects, introducing structural reorientation and grain growth, although, reducing the deposition rate. Accordingly, highly conducting (σ_D10⁻³S cm⁻¹) undoped μc-Si:H film was achieved utilizing energy released by de-excitation of metastable state of Ar (denoted as Ar*), in association with network modulation by atomic hydrogen in the plasma.     

Copper pillar and memory characteristics using Al2O3 switching material for 3D architecture

A novel idea by using copper (Cu) pillar is proposed in this study, which can replace the through-silicon-vias (TSV) technique in future three-dimensional (3D) architecture. The Cu pillar formation under external bias in an Al/Cu/Al₂O₃/TiN structure is simple and low cost. The Cu pillar is formed in the Al₂O₃ film under a small operation voltage of <5 V and a high-current-carrying conductor of >70 mA is obtained. More than 100 devices have shown tight distribution of the Cu pillars in Al₂O₃ film for high current compliance (CC) of 70 mA. Robust read pulse endurances of >10⁶ cycles are observed with read voltages of −1, 1, and 4 V. However, read endurance is failed with read voltages of −1.5, −2, and −4 V. By decreasing negative read voltage, the read endurance is getting worst, which is owing to ruptured Cu pillar. Surface roughness and TiO _x N _y on TiN bottom electrode are observed by atomic force microscope and transmission electron microscope, respectively. The Al/Cu/Al₂O₃/TiN memory device shows good bipolar resistive switching behavior at a CC of 500 μA under small operating voltage of ±1 V and good data retention characteristics of >10³ s with acceptable resistance ratio of >10 is also obtained. This suggests that high-current operation will help to form Cu pillar and lower-current operation will have bipolar resistive switching memory. Therefore, this new Cu/Al₂O₃/TiN structure will be benefited for 3D architecture in the future.     

Coating with artificial matrices from collagen and sulfated hyaluronan influences the osseointegration of dental implants

Dental implants are an established therapy for oral rehabilitation. High success rates are achieved in healthy bone, however, these rates decrease in compromised host bone. Coating of dental implants with components of the extracellular matrix is a promising approach to enhance osseointegration in compromised peri-implant bone. Dental titanium implants were coated with an artificial extracellular matrix (aECM) consisting of collagen type I and either one of two regioselectively low sulfated hyaluronan (sHA) derivatives (coll/sHA1Δ6s and coll/sHA1) and compared to commercial pure titanium implants (control). After extraction of the premolar teeth, 36 implants were inserted into the maxilla of 6 miniature pigs (6 implants per maxilla). The healing periods were 4 and 8 weeks, respectively. After animal sacrifice, the samples were evaluated histomorphologically and histomorphometrically. All surface states led to a sufficient implant osseointegration after 4 and 8 weeks. Inflammatory or foreign body reactions could not be observed. After 4 weeks of healing, implants coated with coll/sHA1Δ6s showed the highest bone implant contact (BIC; coll/sHA1Δ6s: 45.4 %; coll/sHA1: 42.2 %; control: 42.3 %). After 8 weeks, a decrease of BIC could be observed for coll/sHA1Δ6s and controls (coll/sHA1Δ6s: 37.3 %; control: 31.7 %). For implants coated with coll/sHA1, the bone implant contact increased (coll/sHA1: 50.8 %). Statistically significant differences could not be observed. Within the limits of the current study, aECM coatings containing low sHA increase peri-implant bone formation around dental implants in maxillary bone compared to controls in the early healing period.