Measurements of Microstructural, Mechanical, Electrical, and Thermal Properties of an Al–Ni Alloy

The Al–7.5 wt% Ni alloy was directionally solidified upwards with different temperature gradients, $G$ ( $0.86\,\text{ K}~{\cdot }~ \text{ mm}^{-1}$ to $4.24\,\text{ K}~{\cdot }~\text{ mm}^{-1})$ at a constant growth rate, $V$ ( $8.34\,\upmu \text{ m}~{\cdot }~\text{ s}^{-1})$ . The dependence of dendritic microstructures such as the primary dendrite arm spacing ( $\lambda _{1}$ ), the secondary dendrite arm spacing ( $\lambda _{2}$ ), the dendrite tip radius ( $R$ ), and the mushy zone depth ( $d$ ) on the temperature gradient were analyzed. The dendritic microstructures in this study were also compared with current theoretical models, and similar previous experimental results. Measurements of the microhardness (HV) and electrical resistivity ( $\rho $ ) of the directionally solidified samples were carried out. Variations of the electrical resistivity ( $\rho $ ) with temperature ( $T$ ) were also measured by using a standard dc four-point probe technique. And also, the dependence of the microhardness and electrical resistivity on the temperature gradient was analyzed. According to these results, it has been found that the values of HV and $\rho $ increase with increasing values of $G$ . But, the values of HV and $\rho $ decrease with increasing values of dendritic microstructures ( $\lambda _{1}, \lambda _{2}, R,$ and $d$ ). It has been also found that, on increasing the values of temperature, the values of $\rho $ increase. The enthalpy of fusion ( $\Delta {H}$ ) for the Al–7.5 wt%Ni alloy was determined by a differential scanning calorimeter from a heating trace during the transformation from solid to liquid.     

Preparation,characterization, and pharmacokinetics of the inclusion complex of genipin-β-cyclodextrin

Objective: The aim of this study was to prepare the inclusion complex of genipin (GP) and β-cyclodextrin (β-CD) with improved stability, solubility, and bioavailability and to study the pharmacokinetics of β-CD inclusion complex in mice. Methods: Lyophilization was employed in the preparation of the inclusion complex of GP–β-CD, whose formation was confirmed by infrared, ultraviolet, differential scanning calorimetry, X-ray diffraction, and phase solubility method. Comparative studies on the in vitro solubility and stability and in vivo evaluation of GP in mice were investigated. Liquid–liquid extraction was used for the isolation of GP in the assay of its concentration. After injection in the caudal vein at equal doses of the inclusion complex of free GP, the drug concentration in mice plasma at fixed time after administration was determined by high-performance liquid chromatography method. Results: The results demonstrated that GP–β-CD solid powders showed improved stability and solubility in aqueous solution, when comparing with free GP. The results of the in vivo study showed that the inclusion complex of GP–β-CD exhibited the dissimilar pharmacokinetics from that of free GP after intravenous administration. The inclusion complex of GP–β-CD displayed longer MRT_0–∞ and higher AUC_0–∞ than free GP did. Conclusions: The relative bioavailability of the inclusion complex of GP–β-CD to free GP was 305.3%, which demonstrated that GP formulations containing β-CD significantly increased the bioavailability.     

Complex of Programs for Imitative Simulation of Acceleration, Heating, and Melting of Particles in Gas‐Dynamic Channels of Technological Devices

This paper describes an interactive complex of programs designed for investigating the processes of acceleration, heating, and melting of particles in the gasdynamic channels of burners. To illustrate the efficiency of this method, we have investigated the possibility of melting of tungsten particles in the process of their acceleration and heating by combustion products of hydrocarbon fuel in the gasdynamic channel of the burner with the discharge method of acting on the flow.     

Effect of magnesium chloride on growth,crystalline perfection,structural, optical,thermal and NLO behavior of γ-glycine crystals

In the present study, single crystals of γ-glycine possessing excellent non-linear optical properties were successfully grown at room temperature in the presence of magnesium chloride (MgCl₂) for the first time by using the slow solvent evaporation method. The second harmonic conversion efficiency of γ-glycine crystal was determined using Kurtz powder technique with Nd:YAG laser and was found to be 6 times greater than that of the standard inorganic sample potassium dihydrogen phosphate (KDP). The crystalline perfection of the grown crystal was analyzed using high-resolution X-ray diffraction (HRXRD) rocking curve measurements. The grown crystal was subjected to single crystal XRD and powder XRD, which confirmed that the crystal has hexagonal structure and belongs to space group P3₁. Inductively coupled plasma optical emission spectrometry (ICP-OES) was carried out to quantify the concentration of Mg element in the grown γ-glycine single crystal. Fourier transform infrared (FTIR) spectral studies were made to identify the functional groups. The optical band gap was likewise estimated for γ-glycine crystal using UV–vis–NIR study. The optical measurements of γ-glycine crystal helped to calculate the optical constants such as refractive index (n), the extinction coefficient (K), electric susceptibility (χ_c) and both the real (∈_r) and imaginary (∈_i) components of the dielectric permittivity functions of photon energy, which is essentially required to develop optoelectronic devices. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were used to study thermal stability and decomposition point of the grown crystal.     

Analysis of Behaviour of Phase S Capacitive Tap Insulator of Interconnection 1,220 kV, in Jinamar Power Plant （Island of Gran Canaria, Canary Islands, Spain）

In the island of Gran Canaria, Canary Islands, there are two power plants called Jinamar power plant and Barranco de Tirajana Power Plant, both property of Unelco Generacion, a subsidiary of Endesa Generacion. The first one is placed in the northeast of the island, near its capital, Las Palmas de Gran Canaria, and the other is in the southeast, near the most significant touristic area of the island. Both plants are interconnected by means of four transmission lines, two with a voltage of 220 kV and the other two with 66 kV. Since its commissioning in 1995, several phase to ground short circuits have occurred in one of the capacitive tap insulators in the 220 kV lines, in Jinamar side, without a clear cause for them, causing problems of different kind in the electrical system of Gran Canaria. From construction of tap insulators to environmental conditions, every possible factor was carefully studied and laboratory tests were made. In this paper, it is described the analysis which was carried out and how a deep study of every possible cause drove to a definitive solution of the problem.     

Handbook of Statistics,Volume l—Analysis of Variance

Probability plots are popular graphical tools used by reliability engineers and other practitioners for assessing parametric distributional assumptions. They are particularly well suited for location-scale families or those that can be transformed to such families. When the plot indicates a reasonable conformity to the assumed family, it is common to estimate the underlying location and scale parameters by fitting a line through the plot. This quick-and-easy method is especially useful with censored data. Indeed, the current version of a popular statistical software package uses this as the default estimation method. In this article we investigate the properties of graphical estimators with multiply right-censored data and compare their performance with that of maximum likelihood estimators. Large-sample results on consistency, asymptotic normality, and asymptotic variance expressions are obtained. Small-sample properties are studied through simulation for selected distributions and censoring patterns. The results presented in this article extend the work of Nair (1984) to right-censored data.     

Speed, Speed Factor and Power Input of Different Designs of Diffusion Pumps, and Remarks on Measurements of Speed

编者按:国际公认并广泛使用的何氏系数是真空术语中以中国人姓氏命名的系数.何增禄先生(1898--1979-05-12)是我国著名的物理学家、教育家、清华大学著名教授(见<真空>杂志1979年第三期第一页前).下面转载的论文是何增禄先生1932年在美国工作时发表的论文(Physics Volume 2 P386～395 may 1932).这篇在国际上很有影响、曾被很多国家用多种文字转载过的学术论文,我国65岁以下的科技工作者中极少有人读过原文.为纪念何增禄先生并配合发表评述文章,特全文转载,以供读者学习.     

Distribution of crack extension force,the Ĵ-integral,along a through-crack-front of a plate

The -integral is an extension of the J-integral proposed by Rice. It represents the crack-extension force; i.e., the energy release rate per unit of a crack-tip translation in three-dimensional elastic-plastic materials. The distribution of the -integral along the crack-front in a plate subjected to a monotonic loading is determined by a three-dimensional elastic-plastic finite element method.The three-dimensional calculation elucidates that the -integral takes its maximum value at the mid-thickness of the plate and takes a smaller value near the plate surfaces. It is shown that the -integral at the mid-thickness takes an intermediate value between those obtained by two-dimensional plane-strain and plane-stress computations; and that for a compact specimen it agrees with the J-integral value determined from the computed load versus the load-line-displacement curve using the Merkle-Corten formula.

---

Résumé L'intégrale J est une extension de l'intégrale J proposée par Rice. Elle représente une force d'extension d'une fissure, à savoir le taux de relaxation de l'énergie par unité de translation de l'extrémité de la fissure dans des matériaux tridimensionnels élasto-plastiques. On détermine la distribution de l'intégrale J le long du front de fissuration dans une tôle soumise à charge croissante, à l'aide d'une méthode élastoplastique par éléments finis sur trois dimensions.Le calcul tridimensionnel permet d'établir que l'intégrale J revêt sa valeur maximale à mi-épaisseur de la tôle, et une valeur plus faible au voisinage des surfaces de la tôle.On montre que l'intégrale J à mi-épaisseur prend une valeur intermédiaire entre les valeurs ci-dessus, lorsqu'elle est déterminée par calculs à deux dimensions en état plan de déformation on en état plan de tension. On montre aussi que, dans le cas d'une éprouvette compacte, cette valeur est en accord avec la valeur de l'intégrale J établie à partir de la courbe calculée en fonction du déplacement sur la ligne de charge, à l'aide de la formule de Merkle-Corten.

     

Computation of Structural,Mechanical, Thermal,and Magnetic Characteristics of Newly Designed Quaternary Heusler Alloys CoNbCrZ (Z = Al,Ga, Si,Ge)

Journal of Superconductivity and Novel Magnetism - First-principles calculations accomplished to investigate structural, mechanical, thermal and magnetic properties of newly designed CoNbCrZ...     

Thermodynamic Behaviour of Fe-S-RE,Fe-Csat.-S-RE,Ni-S-RE,Cu-S-RE Solutions

The temperature dependences of the equilibrium constants for the reactions RES_((S))=[RE]+[S].(RE=Ce,La,Nd,Sm,Y),of the standard Gibbs energies for the RES formed and of the interactioncoefficients between RE elements and S for the Fe-base,Ni-base and Cu-base solutions are sum-marized.     

Temperature dependence of the Anderson-Grüneisen parameter δ of Co,Ru, and Er

The third-order elastic (TOE) constants of cobalt, ruthenium, and erbium have been calculated as a function of temperature using the nearest neighbor central-force model of Srinivasan and Ramji Rao, taking into account the temperature variation of the second-order elastic (SOE) constants of the metal. The Anderson-Grüneisen (AG) parameter has been evaluated at different temperatures using the respective TOE constants at each temperature for the three metals. It is found that the AG parameter for these metals does not vary markedly with temperature.     

Comparison of the conductance of three types of porphyrin-based molecular wires: β,meso,β-fused tapes, meso-Butadiyne-linked and twisted meso-meso linked oligomers

The length dependence of charge transport is evaluated in three families of porphyrin-based wires. Planar edge-fused tapes and alkyne-linked oligomers mediate efficient charge transport with exceptionally shallow distance dependence, whereas the conductances of the twisted singly linked chains decrease steeply with increasing oligomer length. The planar tapes are more conjugated than the alkyne-linked oligomers, but these two types of wires have similar conductance attenuation factors.     

A study of structural, ferroelectric, ferromagnetic, dielectric properties of NiFe2O4–BaTiO3 multiferroic composites

The mixed spinel-perovskite multiferroic composites of xNiFe₂O₄-(1 ? x)BaTiO₃ (x = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6) have been prepared by sol–gel method. The structure and morphology of the composites were examined by means of X-ray diffraction and transmission electron microscope. High-resolution transmission electron microscope image indicates a clear view of ferrite and ferroelectric phase. Moreover, we observed a fine interface between the two phases, where the coupling effect of ferrite and ferroelectric phase happened. The composites show excellent ferromagnetic and ferroelectric properties. The saturation magnetization (M_s) reaches to 24.139 emu/g for x = 0.6 at room temperature, the magnetization is about 2.37 emu/g for x = 0.6 when the temperature decreases to 90 k, and the polarization reaches to 3.75 μC/cm² for x = 0.1. Frequency dependent variations of dielectric constant and loss tangent for xNiFe₂O₄-(1 ? x)BaTiO₃ were studied in detail.     

Effects of Ga,Al, Ag,and Ce multi-additions on the properties of Sn–9Zn lead-free solder

Wetting balance method is used to evaluate the effects of Ga, Al, Ag, and Ce multi-additions on the solderability of Sn–9Zn lead-free solders, results show that the optimal addition amounts of Ga, Al, Ag, and Ce is 0.2, 0.002, 0.25, and 0.15 wt% respectively. The surface property of Sn–9Zn–0.2Ga–0.002Al–0.25Ag–0.15Ce solder is studied by X-ray photoelectron spectroscopy and auger electron spectroscopy analysis; results indicate that Al aggregates on the surface as a compact aluminum oxide film which prevents the further oxidation. The aggregation of Ce on the subsurface can reduce the surface tension of solder, and improve the solderability accordingly. Meanwhile, SEM and XRD analysis indicate that Cu₅Zn₈ and AgZn₃ intermetallic compounds form at the interface between Sn–9Zn–0.2Ga–0.002Al–0.25Ag–0.15Ce solder and Cu substrate, while AuZn₃ and AuAgZn₂ form at the interface between solder and Cu/Ni/Au substrate. Moreover, results also indicate that the mechanical property of soldered joints is improved duo to the dispersion strengthening effects of AgZn₃ in Sn–9Zn–0.2Ga–0.002Al–0.25Ag–0.15Ce solder.     

Experimental determination of propanol-1 P, ρ, T data

The constant volume piezometer method is used to obtain P, T data for propanol-1 at temperatures of 150–370°K and pressures of 0.1–80 MPa,Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 43, No. 5, pp. 796–798, November, 1982.