Effects of Interaction in Mixtures of Ferroelectric Powders C6H16NBr and PbTiO3

Physics of the Solid State - Phase transitions in the mixture of powders C6H16NBr (DIPAB) and PbTiO3 and composites x-bTiO3–(1 – x)C6H16NBr at x from 0.05 to 0.45 have been studied by...     

A Fast Variant of H Spectroscopic U-FLARE Imaging Using Adjusted Chemical Shift Phase Encoding

So far, fast spectroscopic imaging (SI) using the U-FLARE sequence has provided metabolic maps indirectly via Fourier transformation (FT) along the chemical shift (CS) dimension and subsequent peak integration. However, a large number of CS encoding steps N_ω is needed to cover the spectral bandwidth and to achieve sufficient spectral resolution for peak integration even if the number of resonance lines is small compared to N_ω and even if only metabolic images are of interest and not the spectra in each voxel. Other reconstruction algorithms require extensive prior knowledge, starting values, and/or model functions. An adjusted CS phase encoding scheme (APE) can be used to overcome these drawbacks. It incorporates prior knowledge only about the resonance frequencies present in the sample. Thus, N_ω can be reduced by a factor of 4 for many ¹H in vivo studies while no spectra have to be reconstructed, and no additional user interaction, prior knowledge, starting values, or model function are required. Phantom measurements and in vivo experiments on rat brain have been performed at 4.7 T to test the feasibility of the method for proton SI.     

Fiber-Optic Chemical Sensor for Detection of NO2 Using Poly (3-Octylthiophene)

Abstract

A fiber-optic chemical sensor (FOCS) for detection of nitrogen dioxide (NO ₂ ) molecules is reported. The FOCS presents an optropode structure because of the transmission properties of the sensitive material. The NO ₂ FOCS is activated by using the semiconductor polymer: regioregular head-to-tail poly(3-octylthiophene-2,5-diyl). The operation wavelength of the sensor is 543.5 nm such that a simple LED and detector can be used for the design of this device. The sensor response decreases after each exposure, demonstrating the reduction in sensitivity as well as irreversibility lower than 5%. However, its properties such as rapid response, high selectivity, high sensitivity (0.43 ± 0.01 muW/ppm), hygroscopic properties, and its operation at room temperature make this kind of FOCS a good alternative for NO ₂ toxic gas detection.     

Fiber-Optic Chemical Sensor for Detection of NO2 Using Poly (3-Octylthiophene)

A fiber-optic chemical sensor (FOCS) for detection of nitrogen dioxide (NO₂) molecules is reported. The FOCS presents an optropode structure because of the transmission properties of the sensitive material. The NO₂ FOCS is activated by using the semiconductor polymer: regioregular head-to-tail poly(3-octylthiophene-2,5-diyl). The operation wavelength of the sensor is 543.5 nm such that a simple LED and detector can be used for the design of this device. The sensor response decreases after each exposure, demonstrating the reduction in sensitivity as well as irreversibility lower than 5%. However, its properties such as rapid response, high selectivity, high sensitivity (0.43 ± 0.01 muW/ppm), hygroscopic properties, and its operation at room temperature make this kind of FOCS a good alternative for NO₂ toxic gas detection.     

Comparative Study of Micro and Nano Size WO_3/E44 Epoxy Composite as Gamma Radiation Shielding Using MCNP and Experiment

The radiation shielding characteristics of 50 wt% WO_3/E44 epoxy composite in various gamma energies from80 keV to 1.33 MeV are investigated via the MCNP code. Thus two scales are considered for WO_3 filler particles:micro and nano with sizes of 1,um and 50 nm, respectively. The simulation results show that WO_3 nano particles exhibit a larger increase in linear attenuation coefficient in comparison with micro size particles. Finally, validation of simulation results with the published experimental data shows a good agreement.     

利用曲面逼近进行三维形状恢复

通过对表面形状的平滑性约束,给出了一个关于表面深度和图像亮度的能量函数。并通过对预先给曲面进行调速使得这个能量函数达到极小值,来逼近实际的表面,从而恢复表面形状。这一方法同时利用了图像的局部和全局阴影,避免了只利用局部或全局阴影所带来的误差。通过对合成图像以及实际图像进行的实验,证明该方法是行之有效的。     

H NMR Characterization of the Product from Single Solid-Phase Resin Beads Using Capillary NMR Flow Probes

A capillary NMR flow probe was designed to generate high-resolution ¹H NMR spectra at 600 MHz from the cleaved product of individual 160-μm Tentagel combinatorial chemistry beads. By injecting a dissolved sample sandwiched between an immiscible, perfluorinated organic liquid directly into the probe, NMR spectra of the product cleaved from single beads were acquired in just 1 h of spectrometer time without diffusional dilution. Sample handling efficiency on the single bead scale was comparable to that obtained with a bulk sample. Using the relative intensity of the DMSO-d₅H versus the analyte signals in a fully relaxed CPMG spectrum, the amount of product cleaved from a single bead was determined to be 540±170 pmol in one of the samples. Following the NMR data collection, the samples were examined with electrospray ionization mass spectrometry to provide additional structural information. By coupling with microliter-volume fluidic capabilities, the capillary flow probe described here will enable multidimensional characterization of single solid-phase resin products in an online manner.     

Shear Stress and Dielectric Analysis of H3PO4 Doped Polyaniline Based Electrorheological Fluid

We synthesized phosphoric acid (PA) doped polyaniline (PANI) particles (PANI‐PA) and investigated their electrorheological (ER) and dielectric characteristics when they were dispersed in silicone oil. Flow curves of the PANI‐PA based ER fluid under several applied electric field strengths were analyzed using a shear stress model. We also examined ER characteristics based on the relaxation time obtained from the dielectric spectrum.     

Proton-Conducting Composite Materials Based on the Cs6H(HSO4)3(H2PO4)4 Compound

Physics of the Solid State - xCs6H(HSO4)3(H2PO4)4 + (1 – x)AlPO4 — composition proton conducting materials were obtained in the mass range (x = 0.9–0.7). Their physicochemical and...     

Synthesis of Heterogeneous ZnO/Co3O4 Nanostructures by Chemical Deposition from Solutions

Technical Physics - Nanocrystalline cobalt oxide Co3O4 and composite ZnO/Co3O4 are obtained by chemical deposition from solutions followed by thermal annealing. It is shown that the presence of...     

Total Cross Sections for Electron Scattering from CF4,CF3H,CF2H2,and CFH3 Molecules in Energy Range from 100 to 3000 eV

The additivity rule has been employed to calculate the total cross sections for electron scattering by CF4,CFaH, CF2H2, and CFH3 molecules over an incident energy range from 100 to 3000 eV. Compared with other calculations and experimental data for CF4, excellent agreement has been obtained. Above 1000 eV, there are no experimental data for CF3H, CF2H2, and CFH3, so the present results can provide comparison and prediction for experimental research.     

一种改进型视角投影图像彩色计算全息术的三维重构算法

本文提出了一种利用三维景物的二维视角投影图像合成计算全息图,并重构出彩色再现三维影像的方法.该方法基于利用视角投影图像获取景物的三维傅里叶频谱的理论,采用电荷耦合器件记录三维景物在白光照明条件下横、纵两正交方向的一系列视角投影图像,并利用这些视角投影图像合成计算全息图,从而重构出三维再现像,通过采用在频谱面上的容余采样...     

Nucleon momentum distributions in2H and3He from exclusive and inclusivey-scaling electron scattering

The possibility of obtaining information on nucleon momentum distributions in few-body systems by a coherent analysis of exclusive and inclusive electron scattering is discussed using the concept ofy-scaling.Presented at the symposium Mesons and Light Nuclei, Bechyn, Czechoslovakia, May 27–June 1, 1985.