Physics‐based modeling and microwave characterization of graphene co‐planar waveguides

In this study, large area mono‐, bi‐, and multi‐layer graphenes (MLG) were synthesized using low pressure chemical vapor deposition (LPCVD) process and co‐planar waveguides (CPW) with graphenes being fabricated using conventional photolithography. The intrinsic room temperature radio frequency (RF) characteristics were measured via direct contact to the graphene surface with a probe–tip in the range of 0.1 GHz to 40 GHz without using metal electrodes. The device characteristics were also evaluated by physics‐based RLC equivalent circuit simulation. The proposed equivalent circuit model reproduced all of the measured characteristics within 3% of RMSE and we numerically extracted the set of component values which minimize the error between the measured data and the simulation results over the measured regime. Our findings demonstrate that MLG is an effective candidate in RF interconnect device applications. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The extended serial correspondence on a rich preference domain

We study the problem of assigning objects to a set of agents. We focus on probabilistic solutions that only take agents’ preferences over objects as input. Importantly, agents may be indifferent among several objects. The “extended serial correspondence” is proposed by Katta and Sethuraman (J Econ Theory 131:231–250, 2006) to solve this problem. As a follow-up to Liu and Pycia (Ordinal efficiency, fairness, and incentives in large markets. Mimeo, 2012) who introduce the notion of profiles with “full support”, we work with two interesting classes of preference profiles: profiles that (i) have rich support on a partition or (ii) are single-peaked with rich support on a partition. For each profile in these classes, an assignment matrix is selected by the extended serial correspondence if and only if it is sd-efficient and sd envy-free. We also provide an asymptotic result.     

Combination treatment with 2-methoxyestradiol overcomes bortezomib resistance of multiple myeloma cells

Bortezomib is a proteasome inhibitor used for the treatment of relapsed/refractory multiple myeloma (MM). However, intrinsic and acquired resistance to bortezomib has already been observed in MM patients. In a previous report, we demonstrated that changes in the expression of mitochondrial genes lead to changes in mitochondrial activity and bortezomib susceptibility or resistance, and their combined effects contribute to the differential sensitivity or resistance of MM cells to bortezomib. Here we report that the combination treatment of bortezomib and 2-methoxyestradiol (2ME), a natural estrogen metabolite, induces mitochondria-mediated apoptotic cell death of bortezomib-resistant MM KMS20 cells via mitochondrial reactive oxygen species (ROS) overproduction. Bortezomib plus 2ME treatment induces a higher level of cell death compared with treatment with bortezomib alone and increases mitochondrial ROS and Ca²⁺ levels in KMS20 cells. Pretreatment with the antioxidant N-acetyl-L-cysteine scavenges mitochondrial ROS and decreases cell death after treatment with bortezomib plus 2ME in KMS20 cells. Moreover, we observed that treatment with bortezomib plus 2ME maintains the activation of c-Jun N-terminal kinase (JNK) and mitogen-activated protein kinase kinase kinase 4/7 (MKK4/7). Collectively, combination treatment with bortezomib and 2ME induces cell death via JNK-MKK4/7 activation by overproduction of mitochondrial ROS. Therefore, combination therapy with specific mitochondrial-targeting drugs may prove useful to the development of novel strategies for the treatment of bortezomib-resistant MM patients.     

Lithium‐Functionalized Metal–Organic Frameworks that Show >10 wt % H2 Uptake at Ambient Temperature

We have used grand canonical Monte Carlo simulations with a first‐principles‐based force field to show that metal–organic frameworks (MOFs) with Li functional groups (i.e. C? Li bonds) allow for exceptional H₂ uptake at ambient temperature. For example, at 298 K and 100 bar, IRMOF‐1‐4Li shows a total H₂ uptake of 5.54 wt % and MOF‐200‐27Li exhibits a total H₂ uptake of 10.30 wt %, which are much higher than the corresponding values with pristine MOFs. Li‐functionalized MOF‐200 (MOF‐200‐27Li) shows 11.84 wt % H₂ binding at 243 K and 100 bar. These hydrogen‐storage capacities exceed the 2015 DOE target of 5.5 wt % H₂. Moreover, the incorporation of Li functional groups into MOFs provides more benefits, such as higher delivery amount, for H₂ uptake than previously reported Li‐doped MOFs.     

Possibility of radioactivity measurement using an isothermal microcalorimeter

Journal of Radioanalytical and Nuclear Chemistry - Generally, short-lived medical isotopes and/or their generators are produced in nuclear reactors and cyclotrons. During the last decade, the...     

Effects of substrate temperature on properties of ITO-ZnO composition spread films fabricated by combinatorial RF magnetron sputtering

We have fabricated ITO-ZnO composition spread films to investigate the effects of substrate temperature on their electrical and optical properties by using combinatorial RF magnetron sputtering. It turned out by X-ray measurement that the film with zinc contents above 16.0 at% [Zn/(In+Zn+Sn)] showed amorphous phase regardless of substrate temperature. The amorphous ITO-ZnO film had lower resistivity than polycrystalline films. When the films were deposited at 250 °C, the minimum resistivity of 3.0×10⁻⁴ Ω cm was obtained with the zinc contents of 16.0 at%. The indium content could be reduced as high as ~30 at% compared to that of ITO for the films having similar resistivity (~10⁻⁴ Ω cm). However, a drastic increase of resistivity was observed for the ITO-ZnO films deposited at 350 °C, having zinc contents below 15.2 at%.     

Influence of silver nanoclusters on formation of PbS quantum dots in glasses

Heat-treatment was used to precipitate PbS quantum dots (QDs) in silicate glasses doped with different amounts of Ag₂O, and the influence of Ag₂O on QDs was investigated. Under given heat-treatment conditions, the absorption coefficients and photoluminescence intensities of PbS QDs increased with the addition of Ag₂O. Ag clusters formed by thermal treatment nucleated formation of PbS QDs in glasses.     

Compositional dependences on the mechanism of upconversion in Nd3+/Tm3+ co-doped chalcohalide glasses

Mechanisms of the compositional dependence of blue emission from Nd³⁺/Tm³⁺ co-doped Ge–Ga–S–CsBr chalcohalide glasses were investigated. The blue upconversion emissions (centered at 475 nm) due to the Tm³⁺: ¹G₄ → ³H₆ transition decreased as the CsBr/Ga ratio in glasses while the other upconversion emissions from the Nd³⁺ ions increased. Changes in the local environment of rare-earth ions incurred by the CsBr addition significantly increased the excited state absorption within Nd³⁺ ions. This resulted in the decrease in the Nd³⁺ → Tm³⁺ energy transfer rates that led to the large decrease in blue upconversion emission.     

H2O influence evaluating and mid-IR fluorescence quenching in Tm3+-doped GeGaSCsI chalcohalide glasses

This work presents a detailed study on near-infrared and mid-infrared fluorescence emissions with five sets of Tm³⁺-doped 75GeS₂–15Ga₂S₃–10CsI chalcohalide glass. They are prepared in normal or water drying process. Based on the diffusion-limited relaxation calculation, a detailed investigation is put forward to obtain efficient near-infrared or mid-infrared fluorescence emissions of Tm³⁺ on the effect of H₂O on the Tm³⁺ fluorescence. Detailed investigations are given to the interacted energy transferring processes between rare-earth, impurities and vibrating phonons with the appearance of fluorescence quenching, along with Tm³⁺, H₂O concentrations varying and energy gaps forming. The radioactive properties are analyzed using compensated diffusion-limited relaxation calculation method, and the near-IR and mid-IR fluorescence properties are evaluated in detail with experimental and theoretical analysis.