Characterization of magnetic materials using a scanning microwave microprobe

We investigated the electromagnetic properties of metals of iron, nickel, cobalt, aluminum, gold, copper, silver, and permalloy thin films on SiO(2) substrates using a near-field microwave microprobe. The electromagnetic properties of metal sheets were estimated by measuring the microwave reflection coefficient S(11) and compared with the theoretical values. We observed the hysteresis behavior of permalloy thin films on SiO(2) substrates using a near-field scanning microwave microprobes (NSMM) system. Experimental results are in good agreement with the theoretical model of transmission theory. In order to better characterize the electromagnetic properties of metals and magnetic metals instead of the usual method, we take advantage of the noncontact microprobing evaluation capabilities using a near-field microwave.     

创造水经济系统发展有利条件的探讨

根据地区、年代和季节的不同,许多由水资源缺乏合理分配的复杂问题出现在水资源和水系统管理中.为创建水经济系统发展的有利条件,因此必需要开发和提供长期、计划合理的饮用水和生活用水系统,使其具有可维护性和高生产能力,要减少水的损失,提高水供应的持续时间,并且提升供水和水处理的质量.     

Taking the High Line: elevated parks,transforming neighbourhoods,and the ever-changing relationship between the urban and nature

The popularity and impact of the High Line in New York mirrors the complex reality of contemporary provision of public space. The development of the project, its relationship to its surroundings and the evolving trend of elevated parks are analyzed in relation to the role of urban green space and impacts of Landscape Urbanism.

The High Line shows the way to a new role for urban green space by utilizing abandoned infrastructure. In analysing the narrative of the High Line, this article stresses the importance of understanding localities and connectivity. Based on observations as well as a review of the literature and media, the article concludes that great landscaping does not create great places without careful consideration of the surrounding community and residents.     

Integration of smart windows into building design for reduction of yearly overall energy consumption and peak loads

The purpose of this work is to investigate the potential of diminishing the energy consumed by typical low thermal mass office buildings for heating, cooling and lighting by using smart windows. The windows considered consisted of a double pane glazing unit in which a controllable absorbing layer is added on the interior surface of the exterior glass pane. This absorbing layer allows to change the optical properties of the window, resulting in a direct potential of control of the incident solar heat flux entering the building through the windows. A corresponding numerical model is developed showing that optimizing the solar heat flux absorption rate of the absorbing layer in regard of the necessary heating, cooling and lighting needs helps reducing significantly the total yearly energy consumption, and cooling peak loads. The simulations were done considering a building located in Quebec City, Canada.     

Non-uniform Microdistribution of some Alloys and their Components on Shaped and Rough Cathode Surfaces

Some features of microdistribution of copper-based binary alloys and their components have been studied. If the codeposition rate of the more electropositive component (copper) is at least partially controlled by diffusion, antilevelling takes place for the alloy as a whole. Considerable enrichment of the deposit with respect to the more electropositive component is observed on micropeaks, provided the electrodeposition rate of the more electronegative component is nearly constant at all points of the microprofile (electrodeposition of Cu-Ni alloy from pyrophosphate solution). If the more electropositive component produces a depolarizing effect on the deposition of the more electronegative component, microdistribution of the latter also becomes non-uniform in spite of the absence of diffusion control (Cu-Cd and Cu-Zn alloys). In this case an overall alloy microdistribution shows stronger antilevelling; however, the composition of the deposit becomes more uniform over the microprofile.     

Effects of β-amyloid (1-42) Administration on the Main Neurogenic Niches of the Adult Brain: Amyloid-Induced Neurodegeneration Influences Neurogenesis

Alzheimer’s disease (AD) is the most prevalent neurodegenerative disorder and warrants further study as well as timely treatment. Additionally, the mechanisms of the brain’s intrinsic defense against chronic injury are not yet fully understood. Herein, we examined the response of the main neurogenic niches to amyloid exposure and the associated changes in structure and synaptic activity. Flow cytometry of Nestin-, Vimentin-, Nestin/Vimentin-, NeuN-, GFAP-, NeuN/GFAP-, NSE-, BrdU-, Wnt-, BrdU/Wnt-, VEGF-, Sox14-, VEGF/Sox14-, Sox10-, Sox2-, Sox10/Sox2-, Bax-, and Bcl-xL-positive cells was performed in the subventricular zone (SVZ), hippocampus, and cerebral cortex of rat brains on 90th day after intracerebroventricular (i.c.v.) single injection of a fraction of β-amyloid (Aβ) (1-42). The relative structural changes in these areas and disruptions to synaptic activity in the entorhinal cortex–hippocampus circuit were also evaluated. Our flow analyses revealed a reduction in the numbers of Nestin-, Vimentin-, and Nestin/Vimentin-positive cells in neurogenic niches and the olfactory bulb. These changes were accompanied by an increased number of BrdU-positive cells in the hippocampus and SVZ. The latter changes were strongly correlated with changes in the numbers of VEGF- and VEGF/Sox14-positive cells. The morphological changes were characterized by significant neural loss, a characteristic shift in entorhinal cortex–hippocampus circuit activity, and decreased spontaneous alternation in a behavioral test. We conclude that although an injection of Aβ (1-42) induced stem cell proliferation and triggered neurogenesis at a certain stage, this process was incomplete and led to neural stem cell immaturity. We propose the idea of enhancing adult neurogenesis as a promising strategy for preventing dementia at healthy elderly people andpeople at high risk for developing AD, or treating patients diagnosed with AD.     

Investigation of CdS thin films by a near-field microwave microprobe

Cadmium sulphide (CdS) thin films with different microstructures and morphologies were measured by using a near-field microwave microprobe (NFMM). The NFMM system was coupled to a dielectric resonator with a distance regulation system at an operating frequency f=4.1GHz. The changes in dielectric permittivity of CdS thin films due to different annealing temperatures were investigated by measuring the reflection coefficient S(11). CdS thin films with different microstructures and morphology were characterized by X-ray diffraction, atomic force microscopy and NFMM.     

Physical limitations of the diffusive approximation in semiconductor device modeling

Criteria for occurrence of the quasineutral diffusion mode have been investigated in terms of a generalized approach that takes into account the dependences of the electron and hole velocities on the electric field. These criteria should be used to describe the carrier transport in bases of forward biased bipolar semiconductor devices (diodes, thyristors, and power bipolar transistors in the saturation mode). The criteria appreciably differ from the previously obtained commonly accepted criteria. It is demonstrated that equations describing the carrier transport in the quasineutral approximation in n- and p-type semiconductors are different. These equations are used to obtain analytical conditions in which the diffusion mode is operative. The applicability limits of the diffusion approximation in simulation of semiconductor structures are found. The analytical results are confirmed by a numerical experiment.     

dV/dt effect in high-voltage (1.5 kV) 4H–SiC thyristors

The switching of high-voltage (1.5 kV) 4H–SiC gate turn-off thyristors (GTOs) by the dV/dt effect has been studied in the temperature range from 300 to 504 K. At a 30 ns rise time of the forward bias V(t), the characteristic bias at which the structure under investigation can be switched on by the dV/dt effect decreases steadily from 289 V at room temperature (dV/dt 9.7 kV/μs) to 137 V at T = 504 K. The characteristic critical charge per unit area, Q_cr, equal to 1.9 × 10⁻⁷ C/cm² at room temperature, also decreases steadily as the temperature increases. The main physical mechanisms that contribute to Q_cr formation and the temperature dependence of the critical charge are qualitatively analyzed. The influence exerted by two-dimensional processes on the dV/dt switching is examined by making analytical estimates and using a computer simulation. The results obtained agree well with experimental data.