Heavy quark fragmentation functions at next-to-leading perturbative QCD

It is well-known that the dominant mechanism to produce hadronic bound states with large transverse momentum is fragmentation. This mechanism is described by the fragmentation functions (FFs) which are the universal and process-independent functions. Here, we review the perturbative FFs formalism as an appropriate tool for studying these hadronization processes and detail the extension of this formalism at next-to-leading order (NLO). Using the Suzuki's model, we calculate the perturbative QCD FF for a heavy quark to fragment into a S-wave heavy meson at NLO. As an example, we study the LO and NLO FFs for a charm quark to split into the S-wave $D$-meson and compare our analytic results both with experimental data and well-known phenomenological models

The Effect of Text-Generation on Incidental Vocabulary Learning in Iranian Efl Learners

The present study was undertaken to demonstrate the effect of text-generation on incidental vocabulary learning in Iranian EFL learners. To test the null hypothesis (i.e. there is no significant difference between the vocabulary average performance of the group undergone text-generation processing and the group undergone traditional vocabulary learning processes), two intact classes containing 70 sophomore female and male students of English Translation at Arak State University, Iran participated. A Nelson test of English Language Proficiency (test 250 A) was conducted at the beginning of the study to make sure that the two intact classes did belong to the same population. A multiple choice pre-test was administered at this stage to ensure the insignificant difference between the two groups. The students in the control group were advised to read the texts, whereas the subjects in the experimental group were supposed to use text-generation (reordering the texts) technique while reading the texts. It is worth mentioning that, both groups were provided with the texts in which target vocabulary items were highlighted. At the end of twelve-week period of treatment a multiple choice post-test of vocabulary(the same as pre-test)was administered in both experimental and control groups to compare the subjects' vocabulary achievement. Adopting a quasi-experimental design, the null hypothesis was rejected at 0.05 and (even at 0.01) level of significance for 68 degrees of freedom. Key words: text-generation, incidental vocabulary learning, EF

Site Effects Study in the Mississippi Embayment and Uncertainties Evaluation in Site Response Analysis

Site Effects Study in the Mississippi Embayment and Uncertainties Evaluation in Site Response Analysi

Facile preparation of β-/γ-MgH2 nanocomposites under mild conditions and pathways to rapid dehydrogenation

A magnesium hydride composite with enhanced hydrogen desorption kinetics can be synthesized via a simple wet chemical route by ball milling MgH2 with LiCl as an additive at room temperature followed by tetrahydrofuran (THF) treatment under an Ar atmosphere. The as-synthesized composite comprises ca. 18 mass% orthorhombic γ-MgH2 and 80 mass% tetragonal β-MgH2 as submicron-sized particles. The β-/γ-MgH2 nanocomposite exhibits a dehydrogenation capacity of 6.6 wt.% and starts to release hydrogen at ~260 °C; ca. 140 °C lower than that of commercial MgH2. The apparent activation energy for dehydrogenation is 115±3 kJ mol-1, which is ca. 46 % lower than that of commercial MgH2. Analysis suggests that the meta-stable γ-MgH2 component either directly dehydrogenates exothermically or first transforms into stable β-MgH2 very close to the dehydrogenation onset. The improved hydrogen release performance can be attributed both to the existence of the MgH2 nanostructure and to the presence of γ-MgH2

Luxury Market: Analysis of the driving forces in the context of Iranian luxury hand-woven carpet market

This research is divided in three papers relating to the luxury hand-woven carpet market in Iran. Each of these papers focusing on the effect of brand image dimensions on the various variables such as perceived quality, status consumption and luxury willingness to purchase. All the related data are collected through designed online questionnaires distributed among Iranian consumers and they were analyzed by the last version of R. According to the interesting findings, number of theoretical and managerial contributions were presented in order to pave the way for the retailers and managers of luxury brands in the luxury hand-woven carpet market of Iran to prepare a well-qualified perceived quality of the products for consumers, understanding the motivations behind the status consumption of consumers in this market and finally defining the factors which are lying behind luxury willingness to purchase in this market

RF Sensors for Monitoring the Electrical Properties of Electrolyte Solutions

A radio frequency electrical sensor for the qualitative analysis and monitoring of the electrical properties of electrolyte solutions is designed, simulated and experimentally tested in this research. This work is based on the use of planar inductors for the detection of a change in the concentration of ionic species in a liquid sample. At first a literature review on the physical chemistry of electrolyte solutions is provided. This will include topics on the conductivity and relaxation properties of electrolytes. This will be followed by a look at dielectric spectroscopy sensors, electrochemical sensors and inductive sensing devices. The principles of electrodynamics and constitutive equations are discussed. Based on these, the principles of operation of the RF electrical sensors are analysed. Two methods of theoretical analysis of such structures are investigated. These methods are; analytical solution and finite element computation method. The former offers greater insight into the system’s parameters whilst the latter offers more information regarding the whole system. Given the qualitative nature of the sensors under investigation and finite element approach was selected and used in latter chapters to obtain grater insight into the behaviour of the system. Planar inductor coils are designed on an FR4 substrate and packaged using PDMS to be used as sensors in the monitoring of electrical properties of electrolytes. Experimental results on these sensors are provided and discussed. The effects of solvent, acidity of the solutions, and environmental factors on the behaviour of the sensors shall be discussed. This is followed by finite element simulations of the sensor and the effect of various parameters on the overall behaviour of the sensing device. A transformer apparatus is also constructed and experimental data are provided for it. An electrolyte is placed on one of the coils of the transformer and scattering parameters are looked upon for data analysis. The results obtained using the FE method, is then used to obtain further information about the principle of operation of the device

Preparation and performance of nanostructured iron oxide thin films for solar hydrogen generation

Nowadays, energy and its resources are of prime importance at the global level. During the last few decades there have been several driving forces for the investigation of new sources of energy. Hydrogen has long been identified as one of the most promising carriers of energy. Photoelectrochemical (PEC) water splitting is one of the most promising means of producing hydrogen through a renewable source. Hematite (α-Fe2O3) is a strong candidate material as photoelectrode for PEC water splitting as it fulfils most of the selection criteria of a suitable photocatalyst material for hydrogen generation such as bandgap, chemical and photelectrochemical stability, and importantly ease of fabrication. This work has explored different preparation techniques for undoped and Si-doped iron oxide thin films using microwave-assisted and conventional preparation methods. Two distinct strategies towards improving PEC performance of hematite photoelectrodes were examined: retaining a finer nanostructure and enhancing the photocatalytic behaviour through doping. By depositing thin films using atmospheric pressure chemical vapour deposition (APCVD) and aerosol-assisted CVD (AACVD) at high temperature, it was shown that a combination of different factors (such as silicon incorporation into the hematite structure and formation of lattice defects, along with a nanostructure of small agglomerate/cluster enhancing hole transportation to the surface) were the contributing factors in improving the PEC performance in hematite films. The role of the Si-containing precursors and their consecutive effect on nanostructure of the hematite films were investigated. Further work is needed to study the decomposition pattern of precursors and consequent effects of Si additives as well as co-dopants on fundamental physical and electrical properties of hematite electrodes. In addition, the feasibility of using microwave annealing for the fabrication of iron oxide thin films prepared by electrodeposition at low temperature was also investigated. Hematite films showed improved PEC performance when microwave assisted annealing was used. Microwave heating decreased the annealing temperature by ~40% while the PEC performance was increased by two-fold. The improved performance is attributed to the lower processing temperatures and rapidity of the microwave method that help to retain the nanostructure of the thin films whilst restricting the grain coalescence to a minimum. Around 60% of the energy can be saved using this low carbon foot-print approach compared to conventional annealing procedures for the lab-scale preparation of hematite films – a trait that will have significant implications for scale-up production. The lower processing temperature requirements of the microwave process can also open up the possibility of fabricating hematite thin films on conducting, flexible, plastic electronic substrates

Synthesis and properties of carboxymethylcellulose (CMC) graft copolymer with on-off switching properties for controlled release of drug

Novel biopolymer-based superabsorbent hydrogels were prepared by grafting crosslinked poly (N-vinyl pyrollidin and 2-Acrylamido-2-methyl propan sulfonic acid (PNVP-co-PAMPS) chains onto CMC backbones through a free radical polymerization method. A proposed mechanism for superabsorbent hydrogel formation was suggested and the hydrogel structure was confirmed using FTIR spectroscopy. The morphology of the samples was examined by scanning electron microscopy (SEM). The concentration of released metronidazole loaded was monitored at 245 nm on the UV spectrophotometer. Water absorption of the hydrogel could be switched on and off swiftly by control of pH of the surrounding environment. Therefore, the synthesized hydrogels in this study can be used as a drug delivery system and that the drug release can be controlled by the pH of solution. The release rate of metronidazole from hydrogel at pH 7.4 was higher than that at pH 1.6, due to the increased swelling capacity of the hydrogel.Key words: CMC, hydrogels, release drug, N-vinyl pyrollidin, 2-acrylamido-2-methyl propan sulfonic acid