Electron pumping in graphene mechanical resonators

The combination of high-frequency vibrations and metallic transport in graphene makes it a unique material for nanoelectromechanical devices. In this Letter, we show that graphene-based nanoelectromechanical devices are extremely well suited for charge pumping due to the sensitivity of its transport coefficients to perturbations in electrostatic potential and mechanical deformations, with the potential for novel small scale devices with useful applications.     

Intramolecular Carbonyl Nitroso Ene Reaction Catalyzed by Iron(III) Chloride/Hydrogen Peroxide as an Efficient Tool for Direct Allylic Amination

A mild, simple oxidation protocol employing iron(III) chloride as a catalyst and hydrogen peroxide as a stoichiometric oxidant was found to be compatible with an intramolecular carbonyl nitroso ene reaction and allowed us to efficiently convert hydroxamic acids into a diverse range of 1,2‐ and 1,3‐amino alcohol derivatives in a single operation.     

Field Effect Transistors for Terahertz Detection: Physics and First Imaging Applications

Resonant frequencies of the two-dimensional plasma in FETs increase with the reduction of the channel dimensions and can reach the THz range for sub-micron gate lengths. Nonlinear properties of the electron plasma in the transistor channel can be used for the detection and mixing of THz frequencies. At cryogenic temperatures resonant and gate voltage tunable detection related to plasma waves resonances is observed. At room temperature, when plasma oscillations are overdamped, the FET can operate as an efficient broadband THz detector. We present the main theoretical and experimental results on THz detection by FETs in the context of their possible application for THz imaging.     

Liquid sensor utilizing a regular phononic crystal with normal incidence of sound

A phononic crystal device is investigated as sensor platform utilizing resonant transmission. Here, we use a phononic crystal plate consisting of a solid matrix and liquidfilled holes. The device is fully immersed into the liquid in such a way that the incidence direction of sound is normal to the plate. A characteristic transmission peak, calculated using finite-difference time-domain (FDTD) and determined with two different experimental setups, has been found to strongly depend on the liquid sound velocity. The peak maximum frequency serves as measure for liquid composition.     

Thermal treatment of Aerosil OX50: Pore structure and heats of immersion

Degussa Aerosil OX50 was thermally treated in vacuo, in the temperature range 20–1000°C. Effects of thermal treatment on the water contents, specific surface areas, pore structure and heats of immersion in water were investigated and discussed. Thermogravimetric analysis was used to select the temperatures of thermal treatment which reflect the various textural changes resulting from the heat effects. It could be shown that the heats of immersion in water depend on both the water content of the sample (molecular water and/or surface hydroxyls) and on the surface texture of the silica gel, that is, the pore structure. The interesting result obtained is that the heat of immersion in water is partly proportional to the mesopore fraction of the surface. Micropores lead to a decrease in the heat of immersion in water.     

Pore size restrictions on polymer load and molecular weight in impregnated cement pastes

The polymer load was obtained for various PIC pastes impregnated with polystyrene and polymethyl methacrylate. The effect of some structure-forming conditions of pastes on polymer load was investigated, and these conditions include the fineness of the cement, and W/C ratio and the age of the paste. The variation of the polymer load with sample age is explained on structural basis, and the support is gained from SEM studies. Results of the viscosity average molecular weight of the polymer inside the pore system are also presented, showing their dependence on pore size.     

Raman Light Scattering in System of Oriented Wires in Porous Silicon

Raman-light scattering in porous silicon samples with oriented quantum wires was studied. It was shown, that the experimental data depends on the type of organization of wire system. The explanation of observed effect is discussed.     

Network Polymers Based on Epoxy Oligomers and Dicyandiamide

The formation of network polymers by curing epoxy oligomers with dicyandiamide was investigated. The oligomers had the structure It was shown that the reaction between hydroxyl and epoxy groups is important in this process. The strength-deformation properties of the network polymers obtained were studied. Calculations of elastic active network chains were carried out by the method of branching processes. Good agreement was obtained between calculated and experimental data.     

Hardened Portland blast-furnace slag cement pastes II. The corrosion behavior of steel reinforcement

The corrosion behavior of reinforcing steel embedded in various slag cement pastes was studied using the galvanostatic polarization technique. The corrosion resistance is appreciably affected by the degree of fineness of the dry slag cement. In pastes produced from high Blaine area cement, the behavior of embedded steel was very close to that in normal or type I portland cement paste, and is much better than a low Blaine area cement. W/C ratios of 0.25 and 0.40 provided a better passivating medium as compared with W/C ratios of 0.18 and 0.70. Effects of lime or gypsum addition were also investigated and comparatively studied for their action on the corrosion of embedded steel. The results obtained were supported by corrosion rates obtained using the linear polarization technique.     

MIB-1 proliferation index predicts survival among patients with grade II astrocytoma

The purpose of this study was to determine whether a relationship existed between MIB-1 labeling index (LI) percentages and survival in patients with grade II astrocytomas. From archival paraffin-embedded surgical specimens of 50 patients of the University of Michigan Medical Center with World Health Organization grade II astrocytomas, 22 patients had a Ki-67 LI of less than or equal to 2.0; and 28 patients had a MIB-1 LI of more than 2.0. Over a median follow-up interval of 10 years, ranging up to 16 years, 23% (n = 5) died of tumor in the first group while 82% (n = 23) died in the second group, a distinct difference in survival between these groups. Univariate analysis showed that a high MIB-1 predicted shorter survival (p < 0.0001), and that increased age was associated with shorter survival (p = 0.007). Gender, tumor location and radiotherapy had no significant association with survival. When adjusting for these (excluding tumor location) in the Cox proportional hazards model simultaneously, MIB-1 and age were independently prognostic. The hazard ratios were 1.301 per 1% MIB-1 LI (p = 0.0001), and 1.045 per year of age (p = 0.0028). From other studies, we know that histopathologic grade and age predict survival for glioma patients. However, even within grade II astrocytomas there is still a wide heterogeneity in how long a patient survives. We conclude that among grade II astrocytomas older patients and, independently, patients with higher MIB-1 labeling index have shorter survival.