How Can a Resonant Nanogap Enhance Optical Fields by Many Orders of Magnitude?

In a resonant cavity or a gap, with a nanometer-sized width and depth on an Au surface, filled up with SiO$_2$, the electric field intensity is enhanced by many orders of magnitude by the illumination of a plane wave. Graphical representations of power flow are employed to elucidate how the cavity harvests energy from the incident wave inside to give rise to the enormous field enhancement. The power income from the incident fields into the cavity and the power expense as scattered fields and absorption are discussed on the basis of three Poynting vectors, which correspond to the extinction, scattering, and absorption cross sections. The streamlines of the Poynting vectors distinctly visualize that the cavity collects light from an area much wider than its own geometrical width. In addition, the presence of an alternating power flow accumulated in the cavity for a certain time duration is unveiled on the basis of the real and the imaginary parts of the complex Poynting vector. Both the spatial squeezing and the temporal accumulation contribute to the high power density in the cavity. A clear insight into the underlying physics acquired on the basis of a pictorial understanding is expected to play a critical role in designing a plasmon nanocavity with a higher field enhancement in a rational way.      

Quantification of Choline-containing Compounds in Malignant Breast Tumors by 1H MR Spectroscopy Using Water as an Internal Reference at 1.5 T

The quantification of choline-containing compounds (Cho) in breast tumors by proton MR spectroscopy (¹H-MRS) has been of great interest because such compounds have been linked to malignancy. In this study, an internal reference method for the absolute quantification of Cho metabolite in malignant breast tumors was presented using a clinical 1.5 T scanner. We performed in vitro measurements to examine the accuracy of absolute quantification using four phantoms of known choline chloride concentrations. There was a high correlation between the calculated concentrations by MRS and the known concentrations (r ² > 0.98). We applied the technique to in vivo breast study conducted on 45 patients with biopsy-confirmed breast cancer. After T ₁ and T ₂ relaxation times were corrected, the Cho levels in this work had a range of 0.76 – 21.20 mmol/kg from 34 MR spectra of 32 patients with malignant breast lesions. This result was rather consistent with the previously published value (i.e., 1.38 – 10 mmol/kg, Bolan et al. in Magn Reson Med 50:1134–1143, 2003). Therefore, we conclude that the internal method using the fully relaxed water as a reference could be used for quantifying Cho metabolite accurately in breast cancer patients using a clinical 1.5 T scanner.     

Orientational dependent sensitivities of T2 and T1ρ towards trypsin degradation and Gd-DTPA2? presence in bovine nasal cartilage

Objective

To study the orientational dependencies of T₂ and T_1ρ in native and trypsin-degraded bovine nasal cartilage, with and without the presence of 1?mM Gd-DTPA^2?.

Materials and methods

Sixteen specimens were prepared in two orthogonal fibril directions (parallel and perpendicular), treated using different protocols (native, Gd treated, trypsin-treated, and combination), and imaged using μMRI at 0° and 55° (the magic angle) fibril orientations with respect to the magnetic field B₀. Two-dimensional (2D) T₂ and T_1ρ images were then calculated quantitatively.

Results

Without Gd, native perpendicular tissues demonstrated significant T_1ρ dispersion (including T₂ at the zero spin-lock field) at 0° and less dispersion at 55°, while native parallel specimens exhibited smaller T_1ρ dispersion at both 0° and 55°. Trypsin degradation caused a minimum 50% increase in T_1ρ. With Gd, trypsin degradation caused significant reduction in T_1ρ values up to 60%.

Conclusion

The collagen orientation in nasal cartilage can influence T₂ and T_1ρ MRI of cartilage. Without Gd, T_1ρ was sensitive to the proteoglycan content and its sensitivity was nearly constant regardless of fibril orientation. In comparison, the T₂ sensitivity to proteoglycan was dependant upon fibril orientation, i.e., more sensitive at 55° than 0°. When Gd ions were present, both T₂ and T_1ρ became insensitive to the proteoglycan content.     

Studying the possibility and advisability of operating a Ππ-1900-25-570KT boiler in an oxyfuel combustion mode

Results from calculated studies of the pulverized-coal boiler used as part of a 600-MW power unit that have shown the possibility of its operation in an oxyfuel combustion mode while keeping the design parameters of steam and fulfilling the reliability requirements are presented. The advisability of operating the boiler in such mode is estimated.     

Over hundred experts gathered in the academic activity on energy strategic study——Annual Session of Energy and Information Committee, CSEE held by the end of 1991

The 2nd Annual Session of Energyand Information Committee,CSEE, chaired by Mr. Sun Jiaping was held inBeijing on Dec. 17-20, 1991. Vice MinisterShi Dazhen, Chief Engineer Mr. LuYanchang of the Ministry of Energy, GeneralSecretary Mr. Du Xingyou of CSEE and someother leading staff attended the meeting.Vice Minister Shi Dazhen expressed sincerehope in his address to the session that scien-tific and technical staff in energy fieldshould launch macro policy study morewidely and deeply under the guideline of so-     

Works carried out by ZAO NPK Del’fin-Informatika on developing distributed and hybrid structures of technical means for automated control systems of process equipment at thermal power stations

The field for applying distributed structures of technical means is identified on the basis of experience gained with development of information-computation systems and fully functional automated process control systems. Functions of automated process control systems are pointed out for which centralized processing of data is preferable or necessary in order to support their speed of response and reliability. Experience gained from development of hybrid systems with centralized and distributed processing of information is presented and advisability of constructing them is shown.     

Structural and electrical properties of SrBi2VxNb2?xO9 ferroelectric ceramics: Effect of temperature and frequency

Aurivillius type bismuth layered materials have received a lot of attention because of their application in ferroelectric non-volatile random access memories. Among bismuth layer structured ferroelectric ceramics SrBi₂Ta₂O₉ (SBT)/SrBi₂Nb₂O₉ (SBN) are of great interest for researchers because of their fatigue resistance and less distorted structure. Recently vanadium substitution in SBN/SBT has shown interesting electric and dielectric properties. In the present work, processing conditions, microstructure and electrical studies of vanadium doped SBN ferroelectric ceramics have been performed. Samples of compositions SrBi₂V _x Nb_2-x O₉, x = 0.0, 0.1, 0.3, 0.5 were prepared by solid-state reaction technique using high purity oxides / carbonates. The samples were calcined at 700 °C and sintered at 800 °C. X-ray diffractograms show that a single phase layered perovskite structure is formed in all the samples. Effect of partial substitution of pentavalent niobium ion (0.68 ?) by smaller pentavalent vanadium ion (0.59 ?) at B site on the microstructure, Curie temperature, Dielectric constant, Dielectric loss and electrical conductivity have been investigated. Dielectric properties of SBVN have been investigated from room temperature to 500 °C and frequency of 100 Hz to 1 MHz. Dielectric constant values at their respective Curie points are observed to increase with increasing vanadium concentration. Curie temperature is observed to be maximum in x = 0.1 vanadium doped sample. Strong relaxor like dielectric relaxation at the transition temperatures have been observed. With increasing vanadium concentration the dielectric loss is observed to increase significantly. It is also observed that dielectric loss increases with increase in temperature. The variation of conductivities in these samples is also reported.     

Calculation of phonon spectrum and thermal properties in suspended 〈100〉 In X Ga1?X As nanowires

The phonon spectra in zinc blende InAs, GaAs and their ternary alloy nanowires (NWs) are computed using an enhanced valence force field (EVFF) model. The physical and thermal properties of these nanowires such as sound velocity, elastic constants, specific heat (C _v ), phonon density of states, phonon modes, and the ballistic thermal conductance are explored. The calculated transverse and longitudinal sound velocities in these NWs are ∼25% and 20% smaller compared to the bulk velocities, respectively. The C _v for NWs are about twice as large as the bulk values due to higher surface to volume ratio (SVR) and strong phonon confinement in the nanostructures. The temperature dependent C _v for InAs and GaAs nanowires show a cross-over at 180°K due to higher phonon density in InAs nanowires at lower temperatures. With the phonon spectra and Landauer’s model the ballistic thermal conductance is reported for these III–V NWs. The results in this work demonstrate the potential to engineer the thermal behavior of III–V NWs.     

Discussion of “Optimal reconfiguration and capacitor allocation in radial distribution systems for energy losses minimization” by L.W. de Oliveira et al., International Journal of Electrical Power and Energy Systems 32 (2010) 840–848

This article indicates the accurate method for load level calculation to solve the power flow problem when capacitor reactive power is involved. Using the correct method causes some changes in the results and conclusion stated in the discussed paper on optimal reconfiguration and capacitor placement in radial distribution systems.     

The T-120/130-12.8 and PT-100/130–12.8/1.0 cogeneration steam turbines produced by the ural turbine works for replacing turbines of the T-100 family

The basic design features and technical characteristics of the turbines installed on the foundation of the T-100 family turbines are presented.