Low Temperature Characteristics of the Metal–Superconductor NIS Tunneling Thermometer

We discuss the temperature dependence of a common low temperature local thermometer, a tunnel junction between a superconductor and a normal metal (NIS junction). Towards the lowest temperatures its characteristics tend to saturate, which is usually attributed to selfheating effects. In this technical note, we reanalyze this saturation and show that the temperature independent subgap current of the junction alone explains in some cases the low temperature behavior quantitatively.

     

A new fuzzy‐based method for load balancing in the cloud‐based Internet of things using a grey wolf optimization algorithm

Cloud computing provides high accessibility, scalability, and flexibility in the era of computing for different practical applications. Internet of things (IoT) is a new technology that connects the devices and things to provide user required services. Due to data and information upsurge on IoT, cloud computing is usually used for managing these data, which is known as cloud‐based IoT. Due to the high volume of requirements, service diversity is one of the critical challenges in cloud‐based IoT. Since the load balancing issue is one of the NP‐hard problems in heterogeneous environments, this article provides a new method for response time reduction using a well‐known grey wolf optimization algorithm. In this paper, we supposed that the response time is the same as the execution time of all the tasks that this parameter must be minimized. The way is determining the status of virtual machines based on the current load. Then the tasks will be removed from the machine with the additional load depending on the condition of the virtual machine and will be transferred to the appropriate virtual machine, which is the criterion for assigning the task to the virtual machine based on the least distance. The results of the CloudSim simulation environment showed that the response time is developed in compared to the HBB‐LB and EBCA‐LB algorithm. Also, the load imbalancing degree is improved in comparison to TSLBACO and HJSA.     

Synthesis and characterization of Bi1.5Zn0.92Nb1.5−xSnxO6.92−x/2 pyrochlore ceramics

The morphological, compositional, structural, dielectric and electrical properties of Bi_1.5Zn_0.92Nb_1.5?xSn_xO_6.92?x/2 ceramics have been investigated by means of scanning electron microscopy (SEM), X-ray energy dispersion spectroscopy (EDS), X-ray diffraction (XRD), temperature and frequency dependent dielectric constant and temperature dependent conductivity measurements for Sn-contents in the range of 0.00 ≤ x ≤ 0.60. It was shown that single phase of the pyrochlore ceramics can only be obtained for x ≤ 0.25. Above this value a ZnO phase appeared in the XRD patterns and SEM micrographs as well. An increase in the lattice constant and in the temperature coefficient of dielectric constant and a decrease in the dielectric constant values with increasing Sn content was observed for the ceramics which exhibited a single phase formation. A temperature dependent but frequency invariant dielectric constant was observed for this type of ceramics. The lowest electrical conductivity and highest dielectric constant was observed for the sample which contains 0.06 Sn. The Bi_1.5Zn_0.92Nb_1.5?xSn_xO_6.92?x/2 pyrochlore ceramic conductivities are thermally active above 395 K. For temperatures greater than 395 K, the conductivity activation energy which was found to be 0.415 eV for the pure sample increased to 1.371 eV when sample was doped with 0.06 Sn.     

Renewable resource modified polyol derived aliphatic hyperbranched polyurethane as a biodegradable and UV‐resistant smart material

Renewable resource tailored tough, elastomeric, biodegradable, smart aliphatic hyperbranched polyurethanes were synthesized using castor oil modified polyol containing fatty amide triol, glycerol, diethanolamine and monoglyceride of sunflower oil via an A_x + B_y (x , y ≥ 2) approach. To the best of our knowledge, this is the first report of the synthesis of solely aliphatic hyperbranched polyurethanes by employing renewable resources. The synthesized polyurethanes were characterized by Fourier transform infrared, NMR and XRD techniques. The hyperbranched polyurethanes exhibited good mechanical properties, especially elongation at break (668%), toughness (32.16 MJ m^?3) and impact resistance (19.02 kJ m^?1); also high thermal stability (above 300 °C) and good chemical resistance. Also, the hyperbranched polyurethanes were found to show adequate biodegradability and significant UV light resistance. Moreover, they demonstrated excellent multi‐stimuli‐driven shape recovery ability (up to 97%) under direct sunlight (10⁵ lux), thermal energy (50 °C) and microwave irradiation (450 W). The performance of the hyperbranched polyurethanes was compared with renewable resource based and synthetic linear polyurethane to judge the superiority of the hyperbranched architecture. Therefore, these new aliphatic macromolecules hold significant promise as smart materials for advanced applications. © 2017 Society of Chemical Industry     

Novel Channel and Polarization Assignment Schemes for 2–11 GHz Fixed–Broadband Wireless Access Networks

The scarcity of available spectrum in the 2–11 GHz frequency range and the continuously increasing number of users that require broadband communication services suggest that emerging fixed-broadband wireless access (F-BWA) networks will be deployed with aggressive frequency re-use to cope with capacity demands. In this context, co-channel interference may arise in high levels compromising the system's capacity and robust operation. Interference is further increased when limited directionality terminal antennas are employed to support non line-of-sight operation and in the case where an adaptive-time division duplex is selected for efficient radio resource management in asymmetric and time-varying traffic conditions. In this paper frequency channel assignment (CA) and antenna polarization assignment (PA) are considered as a means of mitigating interference. Two novel CA schemes that consider the distinct characteristics of F-BWA are proposed; the rotated-interleaved channel assignment and the non-uniform channel assignment. According to statistical interference simulation analysis the proposed schemes are more efficient in suppressing interference, achieving higher capacity compared to existing schemes while incurring no further complexity. In addition, instead of exploiting the performance of CA and PA schemes independently a framework for a joint CA-PA consideration is presented, where for a particular CA scheme an optimized PA pattern is developed. Results show that this approach improves the CA-PA interoperability increasing the overall performance. The efficiency of the proposed schemes is investigated for both FDD and adaptive-TDD schemes and is verified for various sectorization, frequency re-use and terminal antenna directivity configurations to ensure compatibility with different deployment scenarios. Bayan Sharif received the bachelor and doctorate degrees from Queens University of Belfast and Ulster University, N. Ireland, in 1984 and 1988. In 1989 he held a research fellowship post at Queens University of Belfast, where he worked on parallel programming algorithms for two-dimensional signal-processing applications. He joined Newcastle University in 1990 as Lecturer, and was promoted to Senior Lecturer and Professor in Digital Communications in 1999 and 2000. During this period he held visiting academic positions with Colorado State University and the UAE Telecommunication Corporation (Etisalat). He is currently Head of the Communications and Signal Processing Research Group at the School of Electrical, Electronic and Computer Engineering and his research interests are in digital communications with a focus on the optimization of wireless networks and DSP algorithms for receiver structures. Prof. Sharif has published over 170 journal and conference papers, and held UK and EU research grants in digital communications and signal processing worth over 2M. He is a Chartered Engineer and Fellow of the IEE. Panos I. Dallas (pdal@intracom.gr) was born 1967 in Thessaloniki, Greece. He obtained his diploma and Ph.D. degree from the Electrical and Computer Engineering Department of Aristotle University of Thessaloniki, Greece, in 1990 and 1997, respectively. Since 1998 he joined with INTRACOM where he currently is Section Manager of Advanced Communications Technologies branch of Emerging Technologies & Markets department, leading the next generation of broadband wireless access systems for internal and EU projects. He runs the relevant standardization activities (IEEE 802.16 and ETSI/BRAN HIPERMAN) in INTRACOM and he represents the company in WiMAX forum. Finally, he has over 30 publications in international journals and conferences. Konstantinos E. Ntagkounak is received the B.Sc. in Electrical Engineering from Technology Institute of Chalkis, Greece, in 1998 and the M.Sc. in Communications & Signal Processing from University of Newcastle, UK, in 2001, where he is currently studying for a Ph.D. in Electrical Engineering. Since 2001, he is with INTRACOM S.A. as a research engineer involved with several European Union IST research projects in the area of Advanced Communication Technologies. His research interests include medium access protocols, radio resource management and network architectures for next generation broadband wireless access systems.     

Preparation and optimization of monodisperse polymeric microparticles using modified vibrating orifice aerosol generator for controlled delivery of letrozole in breast cancer therapy

Abstract

Letrozole (LTZ) is effective for the treatment of hormone-receptor-positive breast cancer in postmenopausal women. In this work, and for the first time, using vibrating orifice aerosol generator (VOAG) technology, monodisperse poly-ε-caprolactone (PCL), and poly (D, L-Lactide) (PDLLA) LTZ-loaded microparticles were prepared and found to elicit selective high cytotoxicity against cancerous breast cells with no apparent toxicity on healthy cells in vitro. Plackett–Burman experimental design was utilized to identify the most significant factors affecting particle size distribution to optimize the prepared particles. The generated microparticles were characterized in terms of microscopic morphology, size, zeta potential, drug entrapment efficiency, and release profile over one-month period. Long-term cytotoxicity of the microparticles was also investigated using MCF-7 human breast cancer cell lines in comparison with primary mammary epithelial cells (MEC). The prepared polymeric particles were monodispersed, spherical, and apparently smooth, regardless of the polymer used or the loaded LTZ concentration. Particle size varied from 15.6 to 91.6?µm and from 22.7 to 99.6?µm with size distribution (expressed as span values) ranging from 0.22 to 1.24 and from 0.29 to 1.48 for PCL and PDLLA based microparticles, respectively. Upon optimizing the manufacture parameters, span was reduced to 0.162–0.195. Drug entrapment reached as high as 96.8%, and drug release from PDLLA and PCL followed a biphasic zero-order release using 5 or 30% w/w drug loading in the formulations. Long-term in vitro cytotoxicity studies indicated that microparticles formulations significantly inhibited the growth of MCF-7 cell line over a prolonged period of time but did not have toxic effects on the normal breast epithelial cells.     

Food safety knowledge and practices among college female students in north of Jordan

Young adults have inadequate knowledge about measures needed to prevent foodborne illnesses. The objectives of this study were to assess the level of food safety knowledge and to investigate the association between the level of food safety knowledge and the socio-demographic and academic variables among college female students staying at dorms in north of Jordan. Information concerning socio-demographic and academic characteristics and food safety knowledge were collected using self-administered questionnaire. Food safety questions included 5 major scales that covered key food safety concepts. A total of 867 female students participated in the study (mean age = 20.07 ± 1.81 years). The overall passing percentage of food safety knowledge was 33.9%. Students were most knowledgeable about prevention of cross contamination and disinfection procedures and had the most difficulties with items related to cooking responsibilities and with food sources of foodborne pathogens. Chi-square results revealed that students who were seniors and in majors related to health sciences, always prepared foods by themselves, reported that they had excellent or very good food safety knowledge, ate out 3 times or less from restaurants, and previously got food poisoning were more likely to pass food safety knowledge questions (P < 0.05). In conclusion, improving students’ knowledge about food safety is an issue that should be taken in consideration; therefore there is a need for developing food safety educational programs that cover key food safety concepts. The school and university setting would be an effective place to reach and teach the young with food safety concepts.     

黑龙江省人造板产业发展状况的研究

通过对黑龙江省人造板产业发展现状的分析和研究,针对人造板产业存在的问题,提出了深化人造板产业体制改革,大力发展林产工业,走规模化、产业化、集团化发展之路的对策和建议。