Processing and characteristics of transparent Gd3TaO7 polycrystalline ceramics

Transparent polycrystalline Gd₃TaO₇ ceramics were successfully developed. A sol‐gel process was used to synthesize Gd₃TaO₇ powder with a uniform composition and an estimated average particle size of 100 nm. Simultaneous thermal gravimetric analysis and differential thermal analysis (TGA/DTA) was used to identify the decomposition sequence as a function of temperature for the as‐synthesized sol‐gel powders. Crystallization was confirmed by X‐ray diffraction (XRD) and a single phase was achieved by calcining at 1000°C. The calcined powders were hot‐pressed at 1400°C to achieve >96% theoretical density with closed pore structure followed by a hot isostatic pressing at 1400°C at 207 MPa to achieve a fully dense structure. Microstructural characterization shows a uniform grain size distribution with an average grain size of about 7 μm. In‐line transmission measurements revealed high transparency in the red and infrared. Thermal conductivity was measured to be >1.6 W/mK at room temperature, decreasing to ~1.3 W/mK by 500°C. Dielectric properties remain stable with relative permittivity values just above 200 and loss tangents <0.005 up to 350°C.     

Highly Efficient and Ultrasensitive Large‐Area Flexible Photodetector Based on Perovskite Nanowires

Hybrid organic–inorganic perovskites have shown exceptional semiconducting properties and microstructural versatility for inexpensive, solution‐processable photovoltaic and optoelectronic devices. In this work, an all‐solution‐based technique in ambient environment for highly sensitive and high‐speed flexible photodetectors using high crystal quality perovskite nanowires grown on Kapton substrate is presented. At 10 V, the optimized photodetector exhibits a responsivity as high as 0.62 A W^?1, a maximum specific detectivity of 7.3 × 10¹² cm Hz^1/2 W^?1, and a rise time of 227.2 µs. It also shows remarkable photocurrent stability even beyond 5000 bending cycles. Moreover, a deposition of poly(methyl methacrylate) (PMMA) as a protective layer on the perovskite yields significantly better stability under ambient air operation: the PMMA‐protected devices are stable for over 30 days. This work demonstrates a cost‐effective fabrication technique for high‐performance flexible photodetectors and opens opportunities for research advancements in broadband and large‐scale flexible perovskite‐based optoelectronic devices.     

Individualization of gasoline samples by covariance mapping and gas chromatography/mass spectrometry

A set of 10 fresh (unevaporated) gasoline samples from a single metropolitan area were differentiated based on a covariance mapping method combined with a t-test statistic. The covariance matrix for each sample was calculated from the retention time-ion abundance data set obtained by gas chromatography/mass spectrometry analysis. Distance metrics were calculated between the covariance matrices from replicate analyses of the same sample and between the replicate analyses of different samples. The distance metric for the same-sample comparisons were shown to constitute a population significantly different from the distance metric for the different-sample comparisons. A power analysis was performed to estimate the number of analyses needed to discriminate between two samples while maintaining a probability of type II error, beta, below 1%, e.g., a test power greater than 99%. Triplicate analyses of two gasoline samples was shown to be sufficient to discriminate between the two using a t-test, while keeping beta<0.01 at a significance level, alpha, of 0.05. Analysis of the 45 possible pairwise comparisons between samples found that 100% of the samples were statistically distinguishable, and no type II errors occurred. Blind tests were conducted wherein 2 of the 10 gasoline samples where presented as unknowns. One of the unknowns was found to be indistinguishable from the original source, and one unknown was determined to be statistically different from the original source, constituting a type I error. The effects of evaporation on sample comparison are not addressed in this paper. The results from this study demonstrate a statistically acceptable method of physical evidence comparison in forensic casework.     

寻找米兰巷弄中的精彩

说到米兰,必令人立刻联想到时尚之都,设计之城。的确,由于时尚的闻名,使得米兰的其它艺术特质都被缩小。其实,除了时尚精品,摩登设计之外,米兰还是个令人陶醉的艺术之都,悠闲之境。她的美值得你花时间慢慢琢磨,用心体会。在室内设计师Augusto Ling(凌玉峰)的引导下,我们将一起探索米兰的独特之处:丰富的艺术,令人赞叹的建筑,个性化的街道巷弄,这些都足以让游客为之感动。就让我们跟着设计师一起探索这些鲜为放大的米兰文化艺术吧!     

The Canadian Problem Gambling Index: Factor structure and associations with psychopathology in a nationally representative sample.

This study examined the factor structure of the Canadian Problem Gambling Index (CPGI), a measure used to assess severity of gambling behaviour in the general population. It subsequently looked at its associations with past-year psychopathology using a subsample (n = 742) of moderate-to-high-risk problem gamblers within the large, nationally representative Canadian Community Health Survey, Cycle 1.2 sample. An exploratory analysis found support for a unifactorial model of the CPGI. Positive associations between problem gambling and various past-year disorders and mental health behaviours were found, with the strongest association being for suicide attempts. These findings help to define the range of maladaptive behaviours associated with problem gambling and their mental health correlates in the Canadian population. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neurofibromatosis Type 1 Gene Alterations Define Specific Features of a Subset of Glioblastomas

Neurofibromatosis type 1 (NF1) gene mutations or alterations occur within neurofibromatosis type 1 as well as in many different malignant tumours on the somatic level. In glioblastoma, NF1 loss of function plays a major role in inducing the mesenchymal (MES) subtype and, therefore defining the most aggressive glioblastoma. This is associated with an immune signature and mediated via the NF1–MAPK–FOSL1 axis. Specifically, increased invasion seems to be regulated via mutations in the leucine-rich domain (LRD) of the NF1 gene product neurofibromin. Novel targets for therapy may arise from neurofibromin deficiency-associated cellular mechanisms that are summarised in this review.     

Resilience: Enhancing well-being through the positive cognitive triad.

The present study tested whether the relationships among resilience, life satisfaction, and depression could be explained by positive views toward the self, the world, and the future (positive cognitive triad). Structural equation modeling and mediation analyses were conducted based on 1,419 college students in Hong Kong. The model of positive cognitive triad as mediator between resilience and well-being fit the data (comparative fit index = .94, Tucker–Lewis index = .93, root-mean-square error of approximation = .08). Findings showed resilience to be significantly related to positive cognitions about the self, the world, and the future. Individuals who had higher level of resilience held significantly more positive cognitions and reported significantly higher levels of life satisfaction and lower levels of depression. The utility of the positive cognitive triad as the mechanism through which resilience enhances well-being was supported. Applications in cultivating resilience and positive cognitions in counseling services are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

艺术气质的大都会之家

艺术品和人一样,也需要空间来自由呼吸,在这个充满纽约大都会风格的现代公寓中。艺术,家具、建筑和设计,缺—不可,它们和谐共生地在同一个空间中,形成一个有个性又有生命力的家。     

Behavior of palladium and its impact on intermetallic growth in palladium-coated Cu wire bonding

This paper describes the behavior of palladium in palladium-coated Cu (PdCu) wire bonding and its impact on bond reliability by utilizing transmission electron microscopy (TEM). A Pd layer approximately 80 nm thick, which is coated on the surface of Cu wire, dissolves into the Cu matrix during ball formation (under N₂ gas protection) when the wire tip is melted to form a ball. As a result of dissolving the very thin Pd layer into the ball, Pd is almost undetectable along the entire bond interface between the ball and the Al pad. The behavior of Pd during thermal aging in air, however, is different for central and peripheral interfaces. At the central interface, less than 5 at.% Pd is present after 168 h aging at 175 °C. At the periphery, however, Pd diffuses back and congregates, reaching a level of ～12 at.% after 24 h, and a Pd-rich (Cu,Pd)₉Al₄ layer (>40 at.% Pd) forms after 168 h. Pd acts substitutionally in Cu₉Al₄ but cannot penetrate into the CuAl₂ or CuAl. By comparison of intermetallic thickness and interfacial morphology between PdCu and bare Cu wire bonds, it is concluded that the presence of Pd reduces intermetallic growth rate, and is associated with numerous nanovoids in PdCu bonds.