Improvement of corrosion resistance of carbon steel using chemical vapor deposition from the mixture of Mo(CO)6 and Cr(CO)6 with an ArF-excimer laser

The corrosion resistance of carbon steel has been improved by the deposition from the mixture of Mo(CO)₆ and Cr(CO)₆ as well as from each carbonyl alone with an ArF-excimer laser (193 nm). The corrosion resistance attained by coating with the films from the mixture is higher than from Mo(CO)₆ alone, while lower than from Cr(CO)₆ alone. While the corrosion resistance increases with beam intensity monotonically over the range 4–25 MW cm^–2 for the deposition from Cr(CO)₆ alone, it tends to decrease slightly above 15 MW cm^–2 for the deposition from Mo(CO)₆ alone and from the mixture. SEM (Scanning Electron Microscope) photographs show that the films from each carbonyl and their mixture consist of small grains that are more densely packed at higher beam intensities. The comparison of the film thickness evaluated from sputtering time to remove the films with that from direct observation with SEM suggests that the density of the film increases with beam intensity. In the films deposited from the mixture, molybdenum is preferentially incorporated from the gas phase. Present name: Department of Quantum Engineering and Systems Science     

The barrier-height inhomogeneity in identically prepared Ni/n-type 6H-SiC Schottky diodes

The effective barrier heights and ideality factors of identically fabricated Ni/n-type 6 H-SiC Schottky diodes (23 dots) have been calculated from their experimental forward bias current–voltage (I–V) and reverse bias capacitance–voltage (C–V) characteristics. A statistical study related to the experimental barrier heights (BHs) and ideality factors of the diodes has been made. The effective Schottky barrier heights (SBHs) and ideality factors obtained from the I–V and C–V characteristics have differed from diode to diode. The BHs obtained from the I–V characteristics varied from 0.85 to 1.03 eV, the ideality factors varied from 1.13 to 1.40 and the BHs from C^-2–V characteristics varied from 1.10 to 1.70 eV. The experimental BH and ideality factor distributions obtained from the I–V characteristics are fitted by a Gaussian function, and their mean values are found to be 0.92±0.04 eV and 1.29±0.08 eV, respectively. The lateral homogeneous SBH value of 1.16 eV for the Ni/n-type 6H-SiC diodes has been calculated from a linear extrapolation of the effective barrier heights to n_if=1.03. PACS 79.40.+z; 73.40.Sx; 73.30.+y; 71.20.Nr     

Evidence for ordered regions in poly(n-butyl)methacrylate from light-scattering studies

From light-scattering studies on polybutylmethacrylate, a polymeric glass, the variation of the velocity and attenuation of thermally excited hypersonic phonons with temperature has been measured. Measurement of the temperature dependence of the ratio of the intensity of the Rayleigh line to the Brillouin lines is interpreted as due to a configurational rearrangement within the glass above the glass transition temperature, T_g . Only light scattered from longitudinal phonons was observed. The distinct change in the temperature dependence of the velocity, attenuation and intensity ratio identified the glass transition.

For samples annealed well above T_g, T_g was found to be about 0°C from the light-scattering studies, 12°C from differential scanning calorimetry (DSC), and 20°C from refractive index measurements. For an unannealed sample the behaviour of the above parameters with temperature was found to be different. T_g for the unannealed sample was 14°C from light-scattering, 18°C from DSC and 20°C from index of refraction measurements.     

Correlation between barrier heights and ideality factors of Cd/n-Si and Cd/p-Si Schottky barrier diodes

Our goal is to experimentally investigate whether or not the effective Schottky barrier heights (SBHs) and ideality factors obtained from the current-voltage (I-V) and capacitance-voltage (C-V) characteristics differ from diode to diode even if the samples were identically prepared. For this purpose, we prepared Cd/n-Si (33 dots) and Cd/p-Si (15 dots) diodes. The SBH for the Cd/n-Si diodes ranged from 0.701 to 0.605 eV, and ideality factor n from 1.913 to 1.213. Φ_b value for the Cd/p-Si diodes ranged from 0.688 to 0.730 eV, and ideality factor n value from 1.473 to 1.040. The experimental SBH distributions obtained from the C⁻²-V and I-V characteristics were fitted by a Gaussian function and their mean SBH values were calculated. Furthermore, the laterally homogeneous barrier heights were also computed from the extrapolation of the linear plot of experimental barrier heights versus ideality factors.     

Optical and structural properties of thin films deposited from laser fused Zirconia,Hafnia, and Yttria

The optical and structural properties of films deposited from laser sintered Zirconia (ZrO₂), Hafnia (HfO₂), and Yttria (Y₂O₃) and from the commercially available (unprocessed material) Zirconia, Hafnia and Yttria, were studied and compared. All the films had low absorption. Films deposited from the laser sintered material had very low optical inhomogeneity. ZrO₂ films showed negative inhomogeneity for films deposited from the unprocessed material. The refractive index increased for ZrO₂ films deposited from the laser sintered material. HfO₂ and Y₂O₃ films showed positive inhomogeneity when deposited from the unprocessed material. The refractive index of the films of these materials decreased when deposited from the laser sintered material. The thin films of ZrO₂ and Y₂O₃ prepared from laser sintered material had stable monoclinic and cubic structures respectively while HfO₂ films were found to be amorphous.     

Adsorption Properties of β‐Cyclodextrin for Adsorbing Aromatic Hydrocarbons from the Gas Phase and Water

β‐cyclodextrin (β‐CD) is a potentially useful adsorbent for the adsorption of aromatic hydrocarbons from the gas phase and water. In this paper, the adsorption properties of β‐CD for adsorbing six aromatic hydrocarbons from the gas phase and seven aromatic hydrocarbons from water were measured. The inverse gas chromatography (IGC) technique was used to characterize the Flory interaction parameters of β‐CD and the six aromatic hydrocarbons from the gas phase at 40, 50, 60, and 70°C. For these aromatic hydrocarbons, the order of β‐CD adsorption ability from strong to weak was: styrene>ethylbenzene>o‐xylene>chlorobenzene>toluene>benzene. For the seven aromatic hydrocarbons in water, adsorption values α, were measured at 20, 30, 40, and 50°C. The order of β‐CD adsorption ability from strong to weak was: ethylbenzene>o‐xylene>styrene>chlorobenzene>toluene>benzene>phenol. This trend was explained based on their solubility degrees in water. It was found that the adsorption abilities of β‐CD for adsorbing aromatic hydrocarbons from the gas phase and water have a similar trend.     

Coherent tunable far infrared radiation

Tunable, cw, far infrared (FIR) radiation has been generated by nonlinear mixing of radiation from two CO₂ lasers in a metal-insulator-metal, (MIM) diode. The FIR difference-frequency power was radiated from the MIM diode antenna to a calibrated indium antimonide bolometer. Two-tenths of a microwatt of FIR power was generated by 250 mW from each of the CO₂ lasers. Using the combination of lines from a waveguide CO₂ laser, with its larger tuning range, with lines from CO₂, N₂O, and CO₂ isotope lasers promises complete coverage of the entire far infrared band from 100 to 5000 GHz (3–200 cm^–1) with stepwise-tunable cw radiation.Contribution of the National Bureau of Standards, not subject to copyright     

Using the 13C/12C carbon isotope ratio to characterise the emission sources of airborne particulate matter: a review of literature

ABSTRACT

Particulate matter (PM) from atmospheric aerosols contains carbons that are harmful for living organisms and the environment. PM can originate from vehicle emissions, wearing of vehicle components, and dust. Size and composition determine PM transport and penetration depth into the respiratory system. Understanding PM emission characteristics is essential for developing strategies to improve air quality. The number of studies on carbon isotope composition (¹³C/¹²C) of PM samples to characterise emission factors has increased. The goal of this review is to integrate and interpret the findings from ¹³C/¹²C carbon isotope ratio (δ¹³C, ‰) analyses for the most common types of emission sources. The review integrates data from 25 studies in 13 countries. The range of δ¹³C of PM from vehicle emissions was from ?28.3 to ?24.5?‰ and for non-vehicle anthropogenic emissions from ?27.4 to ?23.3?‰. In contrast, PM ranges for δ¹³C from biomass burning sources differed markedly. For C₃ plants, δ¹³C ranged from ?34.7 to ?25.4?‰ and for C₄ plants from ?22.2 to ?13.0?‰. The ¹³C/¹²C isotope analysis of PM is valuable for understanding the sources of pollutants and distinguishing vehicle emissions from biomass burning. However, additional markers are needed to further distinguish other anthropogenic sources.     

Determining weak phase γ and probing new physics in b→s transitions from B→η(’)K

We present a method of determining the weak phase γ in the Cabibbo–Kobayashi–Maskawa matrix from the decays B→ηK,η’K alone. Given a large ratio between color-suppressed and color-allowed tree diagrams extracted from global ππ(K) fits, γ is determined from the current data of η’K and the result is in agreement with the global standard model (SM) fits. However, a smaller ratio from factorization based calculations gives γ∼90°. New physics beyond the SM can be distinguished if γ obtained in the η’K modes is significantly different from the ones from other modes or other approaches. The effective value of γ from η’K is very sensitive to new physics contributions and can be used to extract new physics parameters for a class of models which do not give contributions to strong phases significantly. PACS 13.25.Hw; 11.30.Er; 11.30.Hv     

Nearest-neighbor distances in microclusters

The average nearest-neighbor distances of model microclusters, which do not exhibit normal bulk-like packing of the atoms, have been calculated indirectly from the interference function, I(k), assuming that the packing of the microclusters is a normal lattice packing. Physically correct results obtained directly from the radial distribution function (RDF) differ from those calculated from I(k). The RDF nearest-neighbor distances generally exceed the bulk distances while those evaluated from I(k) are less than the bulk values. Recent experimental reports that the nearest-neighbor distances in microclusters, based on measurements of I(k), decrease with decreasing cluster size may thus be incorrect. The error arises from assuming the wrong packing in interpreting the interference function.     

Energy and angular distributions of electrons ejected from CH<Subscript>4</Subscript> and C<Subscript>3</Subscript>H<Subscript>8</Subscript> under 16.0 keV electron impact

Relative cross sections, differential in energy and angle, for electrons ejected from CH₄ and C₃H₈ molecules under 16.0 keV electron impact have been measured. Electrons were analyzed by a 45° parallel plate electrostatic analyzer at emission angles varying from 60° to 135° with energies from 50 eV to 1000 eV. The angular distributions of electrons exhibit structures which are found to arise from Coulomb and non-Coulomb interactions. Furthermore, the double differential cross sections of electrons ejected from C₃H₈ molecule are found to be higher in magnitude than those from CH₄. This result supports the fact that the number of ejected electrons participating in collisions with C₃H₈ molecules is more than that in CH₄. Also, the angular distributions of C-K-shell Auger electrons emitted from the target molecules have been studied and shown to be isotropic within the experimental uncertainty     

Influence of temperature variations on the entropy and correlation of the Grey-Level Co-occurrence Matrix from B-Mode images

In this work, the feasibility of texture parameters extracted from B-Mode images were explored in quantifying medium temperature variation. The goal is to understand how parameters obtained from the gray-level content can be used to improve the actual state-of-the-art methods for non-invasive temperature estimation (NITE). B-Mode images were collected from a tissue mimic phantom heated in a water bath. The phantom is a mixture of water, glycerin, agar-agar and graphite powder. This mixture aims to have similar acoustical properties to in vivo muscle. Images from the phantom were collected using an ultrasound system that has a mechanical sector transducer working at 3.5 MHz. Three temperature curves were collected, and variations between 27 and 44 °C during 60 min were allowed. Two parameters (correlation and entropy) were determined from Grey-Level Co-occurrence Matrix (GLCM) extracted from image, and then assessed for non-invasive temperature estimation. Entropy values were capable of identifying variations of 2.0 °C. Besides, it was possible to quantify variations from normal human body temperature (37 °C) to critical values, as 41 °C. In contrast, despite correlation parameter values (obtained from GLCM) presented a correlation coefficient of 0.84 with temperature variation, the high dispersion of values limited the temperature assessment.     

Temperature effect on water desorption from methylcellulose films studied by thermal FT-IR microspectroscopy

Temperature-induced desorption behavior of water from methylcellulose (MC) film was investigated by a novel microscopic Fourier transform infrared (FT-IR) spectroscopy equipped with thermal analyzer (thermal FT-IR microscopic system) and thermogravimetric analysis (TGA). The result indicates that the weight loss of water from MC film was markedly correlated to the IR spectral changes of OH stretching (3000-3800 cm⁻¹) and bending (1649 cm⁻¹) modes of water molecules. The shift of OH stretching mode from 3461 to 3481 cm⁻¹ was accompanied with the water loss from MC film induced by temperature effect. Two stages of water desorption from MC film were proposed: the first stage within the 35-65 °C had a dramatic IR peak shift from 3461 to 3477 cm⁻¹ and accompanied with a largest weight loss of water from MC film, which might be mainly due to the desorption of free water with minor weakly hydrogen-bonded water; the second stage beyond 65 °C would be desorption of moderately hydrogen-bonded bound water, due to the gradual IR spectral shift from 3477 to 3481 cm⁻¹ and a slower weight loss of water from MC film. The changes in peak area ratio of 1649 cm⁻¹/1374 cm⁻¹ with the temperature also confirmed the IR spectral peak shift of the OH stretching mode via the water loss from MC film. The temperature-dependent dissociation of intermolecular and intramolecular hydrogen bonds within water molecules and/or between water/MC interaction might be responsible for the desorption kinetics of water from MC film.     

脉冲磁控溅射法制备单斜相氧化铒涂层

用中频脉冲反应磁控溅射法,在溅射功率为78 W,93 W和124 W以及衬底温度分别为室温,500 ℃及677 ℃下制备了氧化铒涂层.采用原子力显微镜、纳米压痕、X射线衍射和掠入射X射线衍射法研究了涂层的形貌、力学性能及物相结构.测量了涂层的电学性能.结果显示,脉冲磁控溅射沉积氧化铒涂层具有较高的沉积速率.实验制备得到了单斜相结构的氧化铒涂层.提高溅射功率时,沉积速率从28 nm/min增大至68 nm/min,涂层的结晶质量显著下降.提高衬底温度至500 ℃和677 ℃时,单斜相衍射峰强度下降.分析认为 关键词： 氧化铒 脉冲磁控溅射 单斜晶相     

Effects of nitrogen addition on the microstructures and soft magnetic properties of nanocrystalline Fe86Zr7B6Cu1 ribbons

The effects of nitrogen addition on the microstructures and soft magnetic properties of nanocrystalline Fe₈₆Zr₇B₆Cu₁ ribbons were studied. It is found that the grain size of BCC α-Fe decreases from 13.2 to 9.8 nm with the increase of nitrogen content from 0 to 1.24%. The initial permeability increases from 1.2×10⁴ to 4.4×10⁴ with the increase of nitrogen content from 0 to 0.78%, and then decreases with its further increase. The relaxation frequency increases from 2.5×10⁵ to 7.6×10⁵ Hz with increasing nitrogen content from 0 to 1.24%. The mechanisms for the effects of nitrogen addition on the grain size, the initial permeability, and the relaxation frequency were discussed.     

Isotope Effects during Metabolism of (+)- and (−)- Trans Tramadol Isotopomers by Human Liver Microsomes

Abstract

As for the unlabelled (±)-1(e)-(m-methoxyphenyl)-2(e)-(dimethylaminomethyl)cyclohexane 1(a)-ol, tramadol, (T), pronounced stereochemical effects were observed for the isotopomers with regard to the extent of formation of O- and N-demethylated metabolites. The pharmacological active O-demethylated metabolite M1 was formed from the unlabelled as well as from the labelled (+)-tramadols about 6 times less than from the corresponding (?)-T. In contrast, the N-demethylated metabolite M2 was formed from the (+)-tramadols about 1.5 times more than from the corresponding (?)-T. These steric effects were modulated by the smaller apparent isotope effects for the isotopomers. Isotope effects were expressed as k_H/k_D (calculated from concentrations) and as ^DV, ^DV/K and ^HK_m/^DK_m (from Eadie-Hofstee plots).     

Enhanced luminescence and degradation of SiO2:Ce,Tb powder phosphors prepared by a sol-gel process

Enhanced green photoluminescence and cathodoluminescence (CL) from Tb³⁺ ions due to co-doping with Ce³⁺ ions were observed from SiO₂:Ce,Tb powder phosphors prepared by a sol-gel technique. Blue emission from the Ce³⁺ ions was completely suppressed by Tb co-doping, presumably due to energy transfer from Ce³⁺ to Tb³⁺. In addition, the green CL intensity from SiO₂:Ce,Tb degraded by ∼50% when the powders were irradiated for 10 h with a 2 keV, 54 mA/cm² beam of electrons in an ultra-high vacuum chamber containing either 1×10⁻⁸ or 1×10⁻⁷ Torr O₂. Desorption of oxygen from the surface was observed during the decrease of CL intensity. The mechanisms for energy transfer from Ce³⁺ ions to Tb³⁺ ions to enhance the green luminescence, and mechanisms for desorption of oxygen from the phosphor surface that would result in decreased CL intensity are discussed.     

The absorption of π− at rest on complex nuclei

The energy, width and intensity of prompt nuclear γ-rays following capture of π^? at rest by ⁹Be, ¹⁰B, ¹⁶O, ¹⁹F, ³¹P, Ca and ⁹³Nb were measured with a Ge(Li) detector. In most cases it was possible to identify the final nucleus from the energy of the observed γ-ray. Using the measured Doppler broadening of γ-rays from short-lived states, the vector sum momentum distribution of the emitted nucleons was calculated. From the measured γ-ray intensities, isotopic yields were deduced corresponding to the removal of from 1 to 12 nucleons. The average number of removed nucleons changes from 3.0 to 5.5 as the target varies from ¹⁶O to ⁴⁰Ca. A comparison was made with data from both spallation reactions and multi-nucleon pickup reactions.     

Preparation of LiCoO2 cathode materials from spent lithium–ion batteries

Preparation of LiCoO₂ cathode materials from spent lithium–ion batteries are presented. It started with the reclaim/recycle of metal values from spent lithium–ion batteries, which involves the separation of electrode materials by ultrasonic treatment, acid dissolution, precipitation of cobalt and lithium, followed by the preparation of LiCoO₂ cathode materials. Co (99.4%) and Li (94.5%) were recovered from spent lithium–ion batteries. The LiCoO₂ cathode materials prepared from the reclaimed cobalt and lithium compounds showed good elecrtochemical performance. The reclaiming of cobalt and lithium has a promising outlook for the recycling of cobalt and lithium from spent Li–ion batteries, thus reducing the cost of Li–ion batteries.