Nature of phase transition in magnetic thin films

We study the critical behavior of magnetic thin films as a function of the film thickness. We use the ferromagnetic Ising model with the high-resolution multiple histogram Monte Carlo (MC) simulation. We show that though the 2D behavior remains dominant at small thicknesses, there is a systematic continuous deviation of the critical exponents from their 2D values. We observe that in the same range of varying thickness the deviation of the exponent $\nu$ is very small from its 2D value, while exponent $\beta$ suffers a larger deviation. Moreover, as long as the film thickness is fixed, i. e. no finite size scaling is done in the $z$ direction perpendicular to the film, the 3D values of the critical exponents cannot be attained even with very large (but fixed) thickness. The crossover to 3D universality class cannot therefore take place without finite size scaling applied in the $z$ direction, in the limit of numerically accessible thicknesses. From values of exponent $\alpha$ obtained by MC, we estimate the effective dimension of the system. We conclude that with regard to the critical behavior, thin films behave as systems with effective dimension between 2 and 3.Comment: 8 pages, 17 figures, submitted to Phys. Rev.

Bipolar Magnetic Semiconductors: A New Class of Spintronics Materials

Electrical control of spin polarization is very desirable in spintronics, since electric field can be easily applied locally in contrast with magnetic field. Here, we propose a new concept of bipolar magnetic semiconductor (BMS) in which completely spin-polarized currents with reversible spin polarization can be created and controlled simply by applying a gate voltage. This is a result of the unique electronic structure of BMS, where the valence and conduction bands possess opposite spin polarization when approaching the Fermi level. Our band structure and spin-polarized electronic transport calculations on semi-hydrogenated single-walled carbon nanotubes confirm the existence of BMS materials and demonstrate the electrical control of spin-polarization in them.Comment: 20 pages, 6 figures, accepted by Nanoscal

Chromatin and DNA methylation dynamics during retinoic acid-induced RET gene transcriptional activation in neuroblastoma cells

Although it is well known that RET gene is strongly activated by retinoic acid (RA) in neuroblastoma cells, the mechanisms underlying such activation are still poorly understood. Here we show that a complex series of molecular events, that include modifications of both chromatin and DNA methylation state, accompany RA-mediated RET activation. Our results indicate that the primary epigenetic determinants of RA-induced RET activation differ between enhancer and promoter regions. At promoter region, the main mark of RET activation was the increase of H3K4me3 levels while no significant changes of the methylation state of H3K27 and H3K9 were observed. At RET enhancer region a bipartite chromatin domain was detected in unstimulated cells and a prompt demethylation of H3K27me3 marked RET gene activation upon RA exposure. Moreover, ChIP experiments demonstrated that EZH2 and MeCP2 repressor complexes were associated to the heavily methylated enhancer region in the absence of RA while both complexes were displaced during RA stimulation. Finally, our data show that a demethylation of a specific CpG site at the enhancer region could favor the displacement of MeCP2 from the heavily methylated RET enhancer region providing a novel potential mechanism for transcriptional regulation of methylated RA-regulated loci

Speech language pathologists’ self-report on counselling

Objective: To determine the level of understanding among speech language pathologists regarding counselling. Method: The cross-sectional study was conducted online from July 2020 to January 2021, and comprised speech language pathologists of either gender working in public or private institutions or clinics of Punjab, Sindh and KPK. Data was collected using the Self-report on counselling and interpersonal communication skills’ questionnaire. The collected data was analysed using SPSS 22. Results: Of the 190 subjects, 176(92.6%) were females and 14(7.4%) were males. Majority 173(91.1%) were aged 25-35 years, and 173(91.1%) belonged to the Punjab province. Majority 175(92%) of the respondents reported satisfaction about their own counselling skills, while 168(88.4%) also expressed the need for inclusion of more courses and training to develop counselling and interpersonal communication skills. Conclusion: With experience, professional counselling skills improve and awareness about the need to incorporate counselling training also increases. Key Words: Counselling, Pakistan, Programme, Self report

Teaching strategies for rehabilitation curriculum: coping with the Covid-19 situation

The novel corona virus pandemic culminated in a global emergency shutting down educational institutions with recommendations of distant learning. Developing countries like Pakistan faced challenges in terms of keeping the education stream running. The current narrative review was planned to discuss the teaching strategies adopted by various institutes for coping with the situation created by the coronavirus disease-2019. Literature search was done using search engines and databases with key words ‘Academics’, ‘Coping strategies’, ‘Covid-19’, ‘Online learning’, ‘Rehabilitation curriculum’ and their combinations. As a result, 37 articles were analysed for education involving conformation of curricula to social distancing protocol, and use of video-conferencing software, practical rehabilitation curriculum delivery, and evaluation methods. Developing countries, like Pakistan, should upgrade and revise their rehabilitation curriculum at theoretical and practical levels and try to convert the adversity of the pandemic into an opportunity to develop standardised e-learning programmes and software compatible

Review of Smart City Energy Modeling in Southeast Asia

The Southeast Asian region has been eagerly exploring the concepts of smart city initiatives in recent years due to the enormous opportunities and potential. The initiatives are in line with their plan to promote energy efficiency, phase down/out fossil fuel-based generation, and reduce greenhouse gas emission intensity and electrification of various sectors in addition to renewable energy targets and policies to achieve net zero emissions by 2050 or 2060. However, the major challenges for these countries are related to leadership, governance, citizen support, investment, human capacity, smart device heterogeneity, and efficient modeling and management of resources, especially the energy systems. An intelligent energy system is one of the most significant components for any functional smart city, where artificial intelligence (AI), the internet of things (IoT), and big data are expected to tackle various existing and evolving challenges. This article starts with a brief discussion of smart city concepts and implementation challenges. Then, it identifies different types of smart city initiatives in Southeast Asian countries focusing on energy systems. In addition, the article investigates the status of smart systems in energy generation and storage, infrastructure, and model development. It identifies the unique challenges of these countries in implementing smart energy systems. It critically reviews many available energy modeling approaches and addresses their limitations and strengths, focusing on the region. Moreover, it also provides a preliminary framework for a successful energy system that exploits AI, IoT, and big data. Finally, the roadmap for a successful energy system requires appropriate policy development, innovative technological solutions, human capacity building, and enhancement of the effectiveness of current energy systems

Experimental Investigation of a Plate–Frame Water Gap Membrane Distillation System for Seawater Desalination

This study presented a detailed investigation into the performance of a plate–frame water gap membrane distillation (WGMD) system for the desalination of untreated real seawater. One approach to improving the performance of WGMD is through the proper selection of cooling plate material, which plays a vital role in enhancing the gap vapor condensation process. Hence, the influence of different cooling plate materials was examined and discussed. Furthermore, two different hydrophobic micro-porous polymeric membranes of similar mean pore sizes were utilized in the study. The influence of key operating parameters, including the feed water temperature and flow rate, was examined against the system vapor flux and gained output ratio (GOR). In addition, the used membranes were characterized by means of different techniques in terms of surface morphology, liquid entry pressure, water contact angle, pore size distribution, and porosity. Findings revealed that, at all conditions, the PTFE membrane exhibits superior vapor flux and energy efficiency (GOR), with 9.36% to 14.36% higher flux at a 0.6 to 1.2 L/min feed flow rate when compared to the PVDF membrane. The copper plate, which has the highest thermal conductivity, attained the highest vapor flux, while the acrylic plate, which has an extra-low thermal conductivity, recorded the lowest vapor flux. The increasing order of GOR values for different cooling plates is acrylic 2hr. The system GOR also improves in a decreasing pattern to a maximum value of 0.4049. Moreover, a long-term test showed that the PTFE membrane, which exhibits superior hydrophobicity, registered better salt rejection stability. The use of copper as a cooling plate material for better system performance is recommended, while cooling plate materials with very low thermal conductivities, such as a low thermally conducting polymer, are discouraged

Thermal reaction and stability of NiFe/Cu thin films investigated by atom probe tomography

Ene CB, Schmitz G, Kirchheim R, Hütten A. Thermal reaction and stability of NiFe/Cu thin films investigated by atom probe tomography. In: Surface and Interface Analysis. SURFACE AND INTERFACE ANALYSIS. Vol 39. JOHN WILEY & SONS LTD; 2007: 227-231.NiFe/Cu multilayer stacks of 2 nm single layer thickness were deposited onto needle-shaped W tips by ion beam sputtering and analysed by atom probe tomography (TAP) after appropriate heat treatments. After annealing at 250 degrees C for 30 min, no significant structural or chemical transformation of the initial layer system is detected, although such a heat treatment appreciably reduces the magneto resistivity. A slight decrease of the concentration slope at the interfaces is attributed to a very short-range interdiffusion. Clear grain boundary diffusion is observed after annealing at 400 degrees C for 30 min. Further annealing at 500 degrees C for 20 min and 40 min still preserves the layered structure with a homogeneous solution of Ni inside the Cu layers of up to 25 at.% Ni. Copyright (C) 2007 John Wiley & Sons, Ltd