Understanding the international student experience

Although there are many international students in U.S. higher education institutions, they still experience problems related to social and academic life, as the international student experience is not adequately understood. This may be because of a general lack of awareness relating to the international experience, which can often increase the magnitude of the international students’ problems. Therefore, the purpose of this qualitative study is to provide an overview of the experiences of international students from their own perspectives. Six international graduate students were interviewed for approximately one hour in order to understand their stories in the U.S. Each participant’s story was presented as a case. The participants’ academic, social, and personal experiences were of great interest in this study. Based on the participants’ experiences, everyday life issues, different learning cultures, pursuit of success, social interactions, and personal growth emerged as the thematic findings of this study. These might contribute to the existing body of literature, helping enhance international students’ academic and social experiences abroad. Investigating the international student experience may have a positive influence on faculty members, international student offices, and international students themselves

Density functional and dynamics study of the dissociative adsorption of hydrogen on

a b s t r a c t A first principles study is performed to investigate the adsorption characteristics of hydrogen on magnesium surface. Substitutional and on-surface adsorption energies are calculated for Mg (0 0 0 1) surface alloyed with the selected elements. To further analyze the hydrogen-magnesium interaction, first principles molecular dynamics method is used which simulates the behavior of H 2 at the surface. Also, charge density differences of substitutionally doped surface configurations were illustrated. Accordingly, Mo and Ni are among the elements yielding lower adsorption energies, which are found to be À9.2626 and À5.2995 eV for substitutionally alloyed surfaces, respectively. In light of the dynamic calculations, Co as an alloying element is found to have a splitting effect on H 2 in 50 fs, where the first hydrogen atom is taken inside the Mg substrate right after the decomposition and the other after 1300 fs. An interesting remark is that, elements which acquire higher chances of adsorption are also seen to be competent at dissociating the hydrogen molecule. Furthermore, charge density distributions support the results of molecular dynamics simulations, by verifying the distinguished effects of most of the 3d and 4d transition metals

Advantage of using Web 2.0 applications in class

In this study the advantage of using Web 2.0 applications in terms of increasing student attention and enthusiasm will be emphasized by presenting the example of community service activities which were supported by the blog usage. Copyright 2010 ACM

The effect of video tutorials on learning spreadsheets

In this study a video tutorial for spreadsheet use (Excel) will be prepared by two undergraduate students by using a recorder and applied on a group of students to understand how effective this kind of a tutorial is to increase student achievement. Copyright 2010 ACM

Preživljavanje bakterija Lactobacillus acidophilus LA-5 i Bifidobacterium bifidum BB-12 u sutlijašu

The purpose of this study was to determine the survival of two probiotic micro-organisms (Lactobacillus acidophilus LA-5 and Bifidobacterium bifidum BB-12) in a rice pudding, the impact of these bacteria on hygienic quality, and to verify the perspectives of the product with regard to consumer sensorial acceptance. The products were monitored for the microbial population, pH, titratable acidity and consistency, during storage at 4±1 °C for up to 21 days. Sensory preference was also tested. Even though the viability of the probiotic bacteria was reduced over 21 days of storage, the viable cell concentrations were still sufficient to obtain the desired therapeutic impact. The counts of yeasts-moulds and Staphylococcus spp. decreased in samples with added probiotic bacteria. The sensorial properties of probiotic rice pudding demonstrated similar acceptability to the control up to 14 days and declined thereafter. Rice pudding was considered suitable food for the delivery of probiotic micro-organisms, with sufficient viability and acceptable sensory characteristics.Svrha ovog rada bila je utvrditi preživljavanje probiotičkih mikroorganizama (Lactobacillus acidophilus LA-5 i Bifidobacterium bifidum BB-12) u sutlijašu, utjecaj tih bakterija na higijensku kvalitetu i potvrditi perspektivu proizvoda glede senzorskog prihvaćanja potrošača. U proizvodima je praćena populacija mikroorganizama, pH, titracijska kiselost i konzistencija tijekom skladištenja na 4±1 °C u trajanju do 21 dan. Također su testirana senzorska svojstva. Iako je preživljavanje probiotičkih bakterija smanjeno tijekom 21 dan skladištenja, broj preživjelih mikroorganizama bio je dovoljan da se dobije željeni terapijski učinak. Broj kvasaca, plijesni i Staphylococcus spp. smanjen je u uzorcima s dodatkom probiotičkih bakterija. Sutlijaš se može smatrati pogodnim probiotičkim proizvodom prihvatljivih senzorskih svojstava

A new battery-charging method suggested by molecular dynamics simulations

Based on large-scale molecular dynamics simulations, we propose a new charging method that should be capable of charging a Lithium-ion battery in a fraction of the time needed when using traditional methods. This charging method uses an additional applied oscillatory electric field. Our simulation results show that this charging method offers a great reduction in the average intercalation time for Li+ ions, which dominates the charging time. The oscillating field not only increases the diffusion rate of Li+ ions in the electrolyte but, more importantly, also enhances intercalation by lowering the corresponding overall energy barrier.Comment: 11 pages, 5 figure

The Li intercalation potential of LiMPO4 and LiMSiO4 olivines with M = Fe, Mn, Co, Ni

The Li intercalation potential of LiMPO4 and LiMSiO4 compounds with M = Fe, Mn, Co, and Ni is computed with the GGA+U method. It is found that this approach is considerably more accurate than standard LDA or GGA methods. The calculated potentials for LiFePO4, LiMnPO4 and LiCoOPO4 agree to within 0.1 V with experimental results. The LiNiPO4 potential is predicted to be above 5 V. The potentials of the silicate materials are all found to be rather high, but LiFeSiO4 and LiCoSiO4 have negligible volume change upon Li extraction.Comment: 10 pages, 2 figure

Low thermal conductivity of the layered oxide (Na,Ca)Co_2O_4: Another example of a phonon glass and an electron crystal

The thermal conductivity of polycrystalline samples of (Na,Ca)Co_2O_4 is found to be unusually low, 20 mW/cmK at 280 K. On the assumption of the Wiedemann-Franz law, the lattice thermal conductivity is estimated to be 18 mW/cmK at 280 K, and it does not change appreciably with the substitution of Ca for Na. A quantitative analysis has revealed that the phonon mean free path is comparable with the lattice parameters, where the point-defect scattering plays an important role. Electronically the same samples show a metallic conduction down to 4.2 K, which strongly suggests that NaCo_2O_4 exhibits a glass-like poor thermal conduction together with a metal-like good electrical conduction. The present study further suggests that a strongly correlated system with layered structure can act as a material of a phonon glass and an electron crystal.Comment: 5 pages 3 figures, to be published in Phys. Rev.

Cation- and vacancy-ordering in Li_xCoO_2

Using a combination of first-principles total energies, a cluster expansion technique, and Monte Carlo simulations, we have studied the Li/Co ordering in LiCoO_2 and Li-vacancy/Co ordering in CoO_2. We find: (i) A ground state search of the space of substitutional cation configurations yields the (layered) CuPt structure as the lowest-energy state in the octahedral system LiCoO_2 (and CoO_2), in agreement with the experimentally observed phase. (ii) Finite temperature calculations predict that the solid-state order- disorder transitions for LiCoO_2 and CoO_2 occur at temperatures (~5100 K and ~4400 K, respectively) much higher than melting, thus making these transitions experimentally inaccessible. (iii) The energy of the reaction E(LiCoO_2) - E(CoO_2) - E(Li) gives the average battery voltage V of a Li_xCoO_2/Li cell. Searching the space of configurations for large average voltages, we find that CuPt (a monolayer superlattice) has a high voltage (V=3.78 V), but that this could be increased by cation randomization (V=3.99 V), partial disordering (V=3.86 V), or by forming a 2-layer Li_2Co_2O_4 superlattice along (V=4.90 V).Comment: 12 Pages, RevTeX galley format, 5 figures embedded using epsf Phys. Rev. B (in press, 1998

Voltage, Stability and Diffusion Barrier Differences between Sodium-ion and Lithium-ion Intercalation Materials

To evaluate the potential of Na-ion batteries, we contrast in this work the difference between Na-ion and Li-ion based intercalation chemistries in terms of three key battery properties—voltage, phase stability and diffusion barriers. The compounds investigated comprise the layered AMO2 and AMS2 structures, the olivine and maricite AMPO4 structures, and the NASICON A3V2(PO4)3 structures. The calculated Na voltages for the compounds investigated are 0.18–0.57 V lower than that of the corresponding Li voltages, in agreement with previous experimental data. We believe the observed lower voltages for Na compounds are predominantly a cathodic effect related to the much smaller energy gain from inserting Na into the host structure compared to inserting Li. We also found a relatively strong dependence of battery properties on structural features. In general, the difference between the Na and Li voltage of the same structure, ΔVNa–Li, is less negative for the maricite structures preferred by Na, and more negative for the olivine structures preferred by Li. The layered compounds have the most negative ΔVNa–Li. In terms of phase stability, we found that open structures, such as the layered and NASICON structures, that are better able to accommodate the larger Na+ ion generally have both Na and Li versions of the same compound. For the close-packed AMPO4 structures, our results show that Na generally prefers the maricite structure, while Li prefers the olivine structure, in agreement with previous experimental work. We also found surprising evidence that the barriers for Na+ migration can potentially be lower than that for Li+ migration in the layered structures. Overall, our findings indicate that Na-ion systems can be competitive with Li-ion systems.United States. Office of Naval Research (Contract N00014-11-1-0212)United States. Dept. of Energy (Contract DE-FG02 96ER45571)United States. Dept. of Energy (BATT program under Contract DE-AC02-05CH11231