Junction properties of metal/polypyrrole Schottky barriers

Schottky barriers of the type Au/polypyrrole/Al (or In) were made in sandwich configuration. The conductivity of polypyrrole was tuned to be on the order of 10⁻³ ohm⁻¹ cm⁻¹ by its electrodeposition from a novel ambient temperature ternary eutectic melt consisting of acetamide, urea, and ammonium nitrate. The rectification characteristics were obtained from the current–voltage and capacitance–voltage measurements at room temperature. The analysis of data using thermionic emission theory gave improved values for the junction parameters of ideality factor, reverse saturation current, rectification ratio, and barrier potential when compared to the previously reported values for this polymer. Between Al and In metals used for the junction formation, the diode formed with Al metal is found to show better performance. The energy gap and work function of polypyrrole were also estimated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2127–2135, 2001     

Cellulose acetate ultrafiltration membranes customized with copper oxide nanoparticles for efficient separation with antifouling behavior

Cellulose acetate (CA) nanocomposite ultrafiltration membranes are fabricated with copper oxide (CuO) nanoparticles with the aim of improving efficient protein separation and antifouling performance. CuO nanoparticles are synthesized from cupric nitrate using a wet precipitation method and characterized by FTIR and XRD. CA/CuO nanocomposite membranes fabricated using 0.5, 1.0, and 1.5 wt% of CuO nanoparticles individually by simple phase inversion technique. The CA nanocomposite membrane with 0.5 wt% of hydrophilic CuO exhibited enhanced PWF of 118.6 Lm⁻² h⁻¹ due to the improvement in porosity and water uptake. This is in good agreement with the enhanced hydrophilicity of the CA/CuO nanocomposite membranes results observed in surface contact angle and morphological investigations. Further, 95.5% of BSA separation and 94.7% of flux recovery ratio (FRR) indicates its superior antifouling potential caused due to the presence of the hydration layer at the CA/CuO membrane surface. Among all the fabricated membranes, the CA-0.5 nanocomposite membrane with 0.5 wt% of CuO exhibited superiorly improved hydrophilicity, water permeation, BSA separation, and antifouling performance indicates its potential use in water and wastewater treatment applications.     

Interdependency Analysis of Inter-Site-Distance on Configuration of Handover Control Parameter in LTE-A HetNets

Wireless Personal Communications - Handover (HO) is the procedure performed to maintain the ongoing session of mobile User Equipment (UE). In Long Term Evolution-Advanced (LTE-A) network, the...     

Effect of 8 MeV electron irradiation on the optical properties of PVP capped CdS nanoparticles in PVA matrix

Results of the studies carried out on the effect of electron irradiation on the optical properties of polyvinyl pyrrolidone (PVP) capped cadmium sulphide (CdS) nanoparticles embedded in polyvinyl alcohol (PVA) matrix are reported. PVP capped CdS nanoparticles are prepared by a non-aqueous chemical method with cadmium nitrate as the cadmium source and hydrogen sulphide as the sulphur source. Synthesized nanoparticles are used for X-ray diffraction (XRD) studies that confirmed the formation of cubic CdS nanoparticles with an average size of 3–5 nm. The synthesized CdS nanopowder is dispersed in PVA matrix and self-standing flexible (PVP-CdS) PVA films of thickness 0.2 mm are obtained. The nanocomposites are subjected to optical absorption spectroscopy and photoluminescence (PL) studies. The PL emission spectra of the nanocomposites show two peaks, at 502 and 636 nm, which are attributed to the band edge and surface defects of CdS nanoparticles, respectively. The composite films are irradiated with 8 MeV electrons from a Microtron and optical absorption and PL studies are carried out on the irradiated samples. Irradiation of the samples leads to the quenching of surface defect-related emission.     

Synthesis and stability studies of thiophenol capped CdS nanoparticles

The results of the studies on the preparation and stability of thiophenol-capped CdS nanoparticles prepared by a non-aqueous chemical method are reported. Solutions of cadmium acetate and sodium sulphide were taken as the precursors and thiophenol was used as a capping agent to control the growth and also to prevent flocculation of the synthesized particles. The synthesized CdS nanoparticles were characterized by the optical absorption and X-ray diffraction (XRD) studies. The blue shift of the optical absorption edge indicated the formation of particles in the nanometer size regime. The particle sizes were estimated from the band gap values obtained from the optical absorption spectra using effective mass approximation (EMA). The CdS powder sample was used for the X-ray Diffraction studies. Broadening of the diffraction peaks with an increase in the stabilizer concentration also suggests the decrease in particle size with increase in the stabilizer concentration. Particle sizes calculated from the X-ray diffraction studies agree fairly well with those estimated from the optical absorption studies. The particle size could be conveniently controlled by adjusting the concentration of the stabilizer. X–ray diffraction studies were also carried out at higher temperatures. Particle size did not change with temperature as indicated by XRD. Stability of the synthesized nanoparticles was studied by recording the optical absorption spectra for 45 days. A change in particle size was observed at lower stabilizer concentrations for the first few days. But at higher stabilizer concentrations there was no change in particle size with time.     

Study of n-ZnO/p-Si (100) thin film heterojunctions by pulsed laser deposition without buffer layer

ZnO/Si heterojunctions were fabricated by growing ZnO thin films on p-type Si (100) substrate by pulsed laser deposition without buffer layers. The crystallinity of the heterojunction was analyzed by high resolution X-ray diffraction and atomic force microscopy. The optical quality of the film was analyzed by room temperature (RT) photoluminescence measurements. The high intense band to band emission confirmed the high quality of the ZnO thin films on Si. The electrical properties of the junction were studied by temperature dependent current-voltage measurements and RT capacitance-voltage (C-V) analysis. The charge carrier concentration and the barrier height (BH) were calculated, to be 5.6 × 10¹⁹ cm^− 3 and 0.6 eV respectively from the C-V plot. The BH and ideality factor, calculated using the thermionic emission (TE) model, were found to be highly temperature dependent. We observed a much lower value in Richardson constant, 5.19 × 10^− 7 A/cm² K² than the theoretical value (32 A/cm² K²) for ZnO. This analysis revealed the existence of a Gaussian distribution (GD) with a standard deviation of σ² = 0.035 V. By implementing the GD to the TE, the values of BH and Richardson constant were obtained as 1.3 eV and 39.97 A/cm² K² respectively from the modified Richardson plot. The obtained Richardson constant value is close to the theoretical value for n-ZnO. These high quality heterojunctions can be used for solar cell applications.     

Improved Secure Identification-Based Multilevel Structure of Data Sharing in Cloud Environments

The Cloud Computing Environment (CCE) developed for using the dynamic cloud is the ability of software and services likely to grow with any business. It has transformed the methodology for storing the enterprise data, accessing the data, and Data Sharing (DS). Big data frame a constant way of uploading and sharing the cloud data in a hierarchical architecture with different kinds of separate privileges to access the data. With the requirement of vast volumes of storage area in the CCEs, capturing a secured data access framework is an important issue. This paper proposes an Improved Secure Identification-based Multilevel Structure of Data Sharing (ISIMSDS) to hold the DS of big data in CCEs. The complex file partitioning technique is proposed to verify the access privilege context for sharing data in complex CCEs. An access control Encryption Method (EM) is used to improve the encryption. The Complexity is measured to increase the authentication standard. The active attack is protected using this ISIMSDS methodology. Our proposed ISIMSDS method assists in diminishing the Complexity whenever the user’s population is increasing rapidly. The security analysis proves that the proposed ISIMSDS methodology is more secure against the chosen-PlainText (PT) attack and provides more efficient computation and storage space than the related methods. The performance of the proposed ISIMSDS methodology provides more efficiency in communication costs such as encryption, decryption, and retrieval of the data.     

Voltammetric Method for Manganese Analysis in Indian Traditional Leafy Vegetables and Medicinal Plants Collected Around Tirupati Town, a Famous Pilgrim Center in India: The Catalytic Hydrogen Wave (CHW) Technique

Cost-effective, rapid, sensitive, and novel catalytic hydrogen wave technique (CHW) was developed for the analysis of manganese(II) in NH₄Cl–NH₄OH medium at pH 6.2 and produced catalytic hydrogen waves at −0.60 and −0.56 V Vs SCE with ammonium piperidine dithiocarbamate and ammonium morpholine dithiocarbamate, respectively, in various leafy vegetables and medicinal plants collected around Tirupati, Chittoor District, Andhra Pradesh which is one the famous pilgrim centers in India. Different optimal parameters like effect of pH, supporting electrolyte (NH₄Cl–NH₄OH) concentration, ligand and metal ion concentrations, and effect of adverse ions on peak height were studied to improve the sensitivity, selectivity, and detection limits CHW technique. This technique was compared in terms of Student t test and variance ratio f test with differential pulse polarography (DPP) method. The technique was applied for the analysis of manganese(II) in leafy vegetables and medicinal plants. The results obtained are in good agreement with DPP.     

Effect of orally administered betel leaf (Piper betle Linn.) on digestive enzymes of pancreas and intestinal mucosa and on bile production in rats

The influence of two varieties of betel leaf (Piper betle Linn.) namely, the pungent Mysore and non-pungent Ambadi, was examined on digestive enzymes of pancreas and intestinal mucosa and on bile secretion in experimental rats. The betel leaves were administered orally at two doses which were either comparable to human consumption level or 5 times this. The results indicated that while these betel leaves do not influence bile secretion and composition, they have a significant stimulatory influence on pancreatic lipase activity. Besides, the Ambadi variety of betel leaf has a positive stimulatory influence on intestinal digestive enzymes, especially lipase, amylase and disaccharidases. A slight lowering in the activity of these intestinal enzymes was seen when Mysore variety of betel leaf was administered, and this variety also had a negative effect on pancreatic amylase. Further, both the betel leaf varieties have shown decreasing influence on pancreatic trypsin and chymotrypsin activities.     

Synthesis and characterization of TS-48, a titanium containing silica analog of ZSM-48

Crystalline titanium containing silica analog of ZSM-48 (TS-48) samples were synthesized using soluble peroxytitanate, fumed silica and diamino octane. All samples were characterized using a variety of techniques including XRD, IR, AAS, SEM, UV-Vis, XANES and catalytic testing in hydroxylation of phenol. Data suggest that titanium in these materials is linked to the framework. However, it was impossible to incorporate more than about 2 wt% Ti in the zeolite lattice. TS-48 samples prepared by this method had no activity for hydroxylation of phenol in the presence of hydrogen peroxide. The lack of activity of this material even though it showed all of the regular characteristics of other catalytically active titanium silicalites (i.e., TS-1 and TS-2) could be due either to diffusional limitations or to subtle differences in titanium environment.