Morphological exploration of chemical vapor–deposited P-doped ZnO nanorods for efficient photoelectrochemical water splitting

Photoelectrochemical (PEC) water splitting is beneficial and has received attractive attention due to a greater potential to generate hydrogen and oxygen from water by using plentiful solar light to solve the problem of energy crisis. Various active semiconductor materials are used in PEC water splitting applications. Nevertheless, in past decades, most of the researchers suggested that titanium oxide (TiO₂) is the best photoanode for this type of applications. Now, Zinc oxide (ZnO) is considered a perfect substitution to TiO₂ due to its comparable energy band structure and superior photogenerated electron transfer rate. In this study, bare and phosphorous-doped ZnO nanorods were successfully developed on fluorine-doped tin oxide-coated glass (FTO) substrate by chemical vapor deposition. X-ray diffraction (XRD) pattern authenticated hexagonal structure formation with strong diffraction peak of (101), which showed that ZnO nanorods were perfectly developed along c axis. The optical and morphological properties were analyzed by UV–Vis and scanning electron microscopy images. The energy-dispersive X-ray spectra demonstrated that doping agent phosphorous was present in ZnO nanorods. The PEC properties of the developed ZnO nanorods were further investigated and obtained results suggested that a small amount of phosphorous-doped ZnO nanorods enhances their PEC performance.     

Quantum dot sensitized aluminium doped and copper doped ZnO nanostructure based solar cells

Aluminium doped and copper doped ZnO nanostructured thin films have been prepared using simple solgel dip coating method. The X-ray diffraction pattern results revealed that the prepared Al and Cu doped ZnO sample exhibits hexagonal structure. The average crystallite size of pure ZnO, Al doped ZnO and Cu doped ZnO samples were found to be 29, 26 and 15 nm, respectively. The optical band gap of ZnO, Al doped ZnO and Cu doped ZnO thin films was found to be 3.27, 3.29, and 3.20 eV respectively. Solar cells have been fabricated using CdS quantum dots sensitized ZnO nanostructured thin films and the efficiency of the fabricated Al doped and Cu doped ZnO solar cells were 1.37 and 1.29 % respectively.     

Bi2MoO6 hierarchical microflowers for electrochemical oxygen evolution reaction

Solvothermal Bi₂MoO₆ hierarchical microflowers synthesis has been successfully attempted. Methanol, ethanol and isopropanol have been mediated to synthesize three kinds of Bi₂MoO₆ hierarchical microflowers. Highly oriented (311) plane growth of orthorhombic Bi₂MoO₆ hierarchical microflowers have been confirmed. Interstitial vacancies and its role on electrochemical activity have been extensively discussed. Electrode fabrication was constructively done by using Ni foam substrate. Half cell arrangement of each electrode in alkaline medium has been designed to measure the electrochemical activity towards water oxidation. High current density of 356 mA/cm² was afforded by Bi₂MoO₆ hierarchical microflowers mediated by ethanol solvent during synthesis. Low Tafel slope value of 43 mV/dec has been reported to obtain 10 mA/cm² current density. Higher conductivity long with very good electron transportation has been achieved and is also adapted for 12 h long time stability test and achieved 86% of retention in its performance. Hence, optimally prepared Bi₂MoO₆ hierarchical microflowers could be an efficient electrode for clean energy fabrication.     

Structural,Optical, and Electrical Properties of Cobalt-Doped CdS Quantum Dots

In the present work, a systematic study has been carried out to understand the influence of cobalt (Co) doping on various properties of CdS nanoparticles. CdS and Co-doped CdS quantum dots have been prepared at room temperature using a chemical precipitation method without using catalysts, capping agents, or surfactants. X-ray diffraction reveals that both undoped and Co-doped CdS nanoparticles exhibit hexagonal structure without any impurity phase, and the lattice constants of CdS nanoparticles are observed to decrease slightly with increasing cobalt concentration. High-resolution transmission electron microscopy (HRTEM) shows that the particle size of CdS and 5.02% Co-doped CdS nanoparticles is in the range of 2 nm to 4 nm. The Raman spectra of Co-doped CdS nanoparticles exhibit a red-shift compared with that of bulk CdS, which may be attributed to optical phonon confinement. The optical absorption spectra of Co-doped CdS nanoparticles also exhibit a red-shift with respect to that of CdS nanoparticles. The electrical conductivity of CdS and Co-doped CdS nanoparticles is found to increase with increasing temperature and cobalt concentration.     

Dye-sensitized solar cells with natural dyes extracted from rose petals

Nanocrystalline TiO₂ dye-sensitized solar cells have been fabricated using TiO₂ photoelectrode sensitized using the extracts of red rose and table rose as natural sensitizers and their characteristics have been studied. The extracts having anthocyanin pigment (pelargonidin, peonidin and cyanidin), which have hydroxyl and carboxylic groups in the molecule can attach effectively to the surface of TiO₂ film. The solar cell constructed using the red rose sensitized TiO₂ photo-electrode exhibited a short-circuit photocurrent of 4.57 mA/cm² and a power conversion efficiency of 0.81 % and that of table rose sensitized TiO₂ photo-electrode exhibited a short-circuit photocurrent of 4.23 mA/cm² and a power conversion efficiency of 0.67 %. Natural dye sensitized TiO₂ photo electrodes present the prospect to be used as an environment-friendly, low-cost alternative system.     

In vitro expansion of CD34+ cells from peripheral blood of myeloma and lymphoma patients

We studied the feasibility of in vitro expansion of CD34+ cells from patients with multiple myeloma (MM) or follicular non Hodgkin lymphoma (NHL). CD34+ cells were selected from peripheral blood (PB) using avidinbiotin immunoadsorption columns: purified CD34+ cells from three MM and five NHL patients were expanded. First, CD34+ cells (2 MM, 4 NHL) were grown for 14 days in 5 ml of IMDM plus 12.5% horse serum (HS), 12.5% fetal calf serum (FCS) and a commonly used combination of cytokines: IL1alpha, IL3, IL6, SCF, GM-CSF, G-CSF (10 ng/ml each) and EP (4 UI/ml). In these conditions, at day 14, average increase in CD34+, CFU-GM and total cell numbers were, respectively: x 6.0 x 23 and x 2,113 fold with 20 to 35% of granulocytic cells. In terms of CD34+ cell, CFU-GM and total cell outputs, MM cultures were comparable to NHL cultures, but MM cultures seemed to produce less granulocytic cells than NHL cultures. Next, in vitro expansion of PB CD34+ cells was tested in culture media suitable for clinical use. Two cultures (1 MM, 1 NHL) were carried out for 14 days in 20 ml of X-Vivo 10 medium, 2% human serum, IL1alpha, IL3, IL6, SCF, GM-CSF, G-CSF (6 ng/ml each) and EP (2 UI/ml). Increase in CD34+, CFU-GM and total cell numbers in these conditions were, respectively: x 5.7 and x 19.7, x 11.9 and x 40.9, x 424 and x 408 fold, with at least 75% of granulocytic cells in both cultures. We conclude that, although further improvements are necessary, in vitro expansion of PB CD34+ cells can presumably be carried out successfully for MM patients as well as for NHL patients, including in conditions suitable for clinical use.     

Copper molybdate nanoparticles for electrochemical water splitting application

Two different phases of copper molybdate nanoparticles such as Cu₃Mo₂O₉ and Cu₆Mo₅O₁₈ were synthesized through schematic hydrothermal treatment. The obtained product morphology was explored by using surfactants like sodium lauryl sulfate (SDS) and polyvinylpyrrolidone (PVP). The structural, optical, vibrational and morphological properties were confirmed employing standard characterization techniques. Rectangular nanoflakes of the obtained product were confirmed by employing Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) studies. Selected area electron diffraction (SAED) pattern confirms obtained product crystalline nature. The better morphology controlled sample gives higher 227 mA/g current density at 10 mV/s and small 184 V overpotential. Long duration stability over 16 h was exhibited by Cu₆Mo₅O₁₈ electrode. Hence, Cu₆Mo₅O₁₈ electrode shows better electrochemical activity with stunning low overpotential. It would be suggested that PVP surfactant is quite optimum to produce efficient Cu₆Mo₅O₁₈ catalysts for electrochemical water splitting applications.     

Explicit thickness integration for three-dimensional shell elements applied to non-linear analysis

The problem of multilayered degenerated 3-D shell elements for which the numerical integration is performed for each ply is that of the high generation time in non-linear analysis when the number of plies is important. But these elements give accurate results for thin and moderately thick shells, so in order to reduce the generation time explicit thickness integration is investigated. We first write an expansion of the strain-displacement matrix in power series of the thickness variable in order to obtain explicit expressions of the tangent stiffness matrix and internal force vector, appearing in the non-linear formulation. Explicit expressions of non-linear stiffness matrices are presented, using the explicit integration-first approximation. Simple expressions of several matrices, sub-matrices and vectors appearing in the formulation are given here in order to obtain an important computing-time gain. Next, some numerical validation tests comparing the classical element with numerical thickness integration and this one are discussed to prove validity of this formulation.     

Classification using information

Let be a set of functions. A classifier for is a way of telling, given a function f, if f is in . We will define this notion formally. We will then modify our definition in three ways: (1) allow the classifier to ask questions to an oracle A (thus increasing the classifiers computational power), (2) allow the classifier to ask questions about f (thus increasing the classifiers information access), and (3) restrict the number of times the classifier can change its mind (thus decreasing the classifiers information access). By varying these parameters we will gain a better understanding of the contrast between computational power and informational access. We have determined exactly (1) which sets are classifiable (theorem 3.6), (2) which sets are classifiable with queries to some oracle (theorem 3.2), (3) which sets are classifiable with queries to some oracle and queries about f (theorem 5.2), and (4) which sets are classifiable with queries to some oracle, queries about f and a bounded number of mindchanges (theorem 5.2). The last two items involve the Borel hierarchy. This revised version was published online in June 2006 with corrections to the Cover Date.