Density of α-pinene, Β-pinene,limonene, and essence of turpentine

Densities of ga-pinene, -pinene, limonene, and essence of turpentine have been measured at 293.15, 298.15, 303.15, 308.15, and 313.15 K, at atmospheric pressure, with a mechanical oscillator densimeter. Benzene and cyclohexane were used as calibration fluids. The precision is of the order of 0.01 kg · m^–3, while the accuracy is estimated to be 0.1%. A linear representation of the variation of the density with temperature reproduces the experimental data within 0.2%.     

Half-Lives and Intensities of X-ray and γ-Ray Emission of 113Sn, 117mSn,and 119mSn

The nuclear-physical properties of ¹¹³Sn, ^117mSn, and ^119mSn were studied by semiconductor X-ray and -ray spectrometry. The following energies (keV) and intensities (rel. units, in parentheses) of X-ray and -emission were obtained. ¹¹³Sn: 255 (3.2), 392 (100); ^117mSn: 156 [2.4(1)], 158 (100); ^119mSn: 23.8 [71.6(15)], KX 25 (100), intensity ratio 0.716(15). The K K ratios for ¹¹³Sn, ^117mSn, and ^119mSn are 4.5(1), 4.6(2), and 4.4(2), and the half-lives T _1/2 of these nuclides (days) are 115±1, 13.98±0.07, and 285±9, respectively (the errors are given for the confidence level of 0.95). The results are compared to the published 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.     

Density and solubility of nafion: recast, annealed, and commercial films

The density of Nafion membranes wetted in water and acetonitrile and the solubility of Nafion in a 50:50 ethanol/water mixture are reported. Commercially available membranes, solution recast membranes, and recast membranes thermally processed for varying lengths of time were examined. Unheated recast membranes were found to be ～20% less dense in water than both commercial membranes and recast membranes heated at 140 °C for 40, 50, and 60 min. For heating times of ≥40 min, the density of recast membranes in water was invariant and equal to the density of commercial films. Similarly, in acetonitrile, commercial membranes and films heated for 1 h had the same density; unheated recast films were ～25% less dense. Nafion density in acetonitrile was ～15% less than that in water. Acid pretreatment reduced Nafion film density by ～15%. Unheated recast films were 22-100% soluble in a sonicated ethanol/water mixture. Commercial membranes and recast films heated for as little as 10 min were insoluble under the same conditions.     

Simulations and experiments of open hole tension tests – Assessment of intra-ply plasticity,damage, and localization

Laminated composites with various layups of unidirectional carbon fiber reinforced epoxy are investigated by numerical modeling and experimental testing. Open hole tension configurations are studied with special considerations of the non-linear behavior of the plies. Computational predictions are based on an anisotropic constitutive material law which includes plasticity and damage, the latter comprise hardening as well as softening. Experimental evaluations include a 3D image correlation photogrammetry system for capturing the strain fields of the sample surfaces.     

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.     

Formulation and Comparative Characterization of Chitosan,Gelatin, and Chitosan–Gelatin-Coated Liposomes of CPT-11–HCl

Liposomes containing phosphatidylcholine and cholesterol (uncoated) and coated by chitosan, gelatin, and combination of chitosan and gelatin were prepared by the modified ethanol injection method. The aim of this work was to formulate and characterize liposomes of camptothecin (CPT)-11–HCl (Irinotecan HCl) containing chitosan, gelatin, and both polymers as coating materials; and also to increase its circulation longevity when compared with the free drug while maintaining the agent in its active lactone form. Size, shape, zeta potential, encapsulation efficiency, stability study, in vitro, and in vivo release study were used for characterization of liposomes. The size of liposomes was in the order of uncoated?<?chitosan coated?<?gelatin coated?<?combination of chitosan and gelatin coated. The zeta potential of liposomes was in the order of combination of chitosan and gelatin coated?>?chitosan coated?>?gelatin coated?>?uncoated. The formulations showed the long-term stability. The encapsulation efficiency of liposomes was in order of combination of chitosan and gelatin coated?>?gelatin coated?>?chitosan coated?>?uncoated. The in vitro and in vivo release of drug was observed in the order of combination chitosan and gelatin coated?>?gelatin coated?>?chitosan coated?>?uncoated.     

Structural, Electronic and Magnetic Properties of Nanolayer and?Bulk of MnCo2Si and MnFeCoSi Compounds

In the present work we have investigated the structural, electronic and magnetic properties of MnCo₂Si and MnFeCoSi in bulk and nanolayer using density functional theory. The total energies as a function of volume are calculated and thereby the bulk modulus and their pressure derivatives are determined. The effect of atoms at the surface of these nanolayers has been analyzed using the calculated total and partial electron density of states in its ferromagnetic phase. The spin-polarized density of states show that both bulk MnCo₂Si and MnFeCoSi present a half-metallicity, which is lost at their nanolayer surfaces. Furthermore, the effects of pressure on the magnetic moment of these compounds in its bulk form are investigated.     

Structure,properties and production of β-alumina

The crystal structures of the -alumina compositions have been described and used to explain the fast ion transport for which these materials are renowned. Measured values of both the single crystal and polycrystalline ionic conductivity show a wide variation; this is explained in terms of the range of chemical compositions of the -alumina system and also the variety of measuring techniques used. Dopants or impurity ions can have a significant effect on the physical properties of the -aluminas. The ionic conductivity, the stability of the material and the densification during sintering have been considered in relation to the nature and level of a range of dopants described in the literature. The optimization of the ionic and mechanical properties has been achieved by development of the fabrication techniques and it is this which accounts for much of the present research. Thus the many different methods of producing both single and polycrystalline material have been described, including the range of sintering routes currently available. The advantages and disadvantages of each production route in terms of the resulting properties have also been discussed.     

Dilute Solution Behavior of Dendrimers and Polysaccharides: SEC, ESI-MS, and Computer Modeling

Dendrimers, the most highly branched structures achievable, have found numerous uses in the chemical, biological, and pharmaceutical fields. We have employed size exclusion chromatography (SEC) with universal calibration to determine molecular weight averages, distributions, intrinsic viscosities, and structural parameters of Starburst dendrimers, dextrans, and the starch degradation polysaccharides known as maltodextrins. Comparisons have been made in the dilute solution behavior of dendrimers and polysaccharides with equivalent weight-average molecular weights. Intrinsic viscosities decreased in the order [η](dextran) > [η](dextrin) > [η](dendrimer). While the difference between dendrimer and polysaccharides may be attributed to the higher branching of the former, which leads to a higher chain density in solution, the difference between dextran and dextrin is likely a result of the variation in solution behavior of α-(1→6) vs α-(1→4) linked carbohydrates. The solution behavior of the maltodextrins studied indicates that debranching in their manufacture appears to have been more thorough than in that of β-limiting dextrins studied by other groups. Comparison of molecular radii obtained from SEC data to radii from molecular dynamics studies show Starburst dendrimers behave as θ-stars with functionality between 1 and 4. Additionally, electrospray ionization mass spectrometry was employed to determine M(w), M(n), and PD of Astramol dendrimers.     

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.     

Fabrication and fluorescence properties of multilayered core–shell particles composed of quantum dot,gadolinium compound,and silica

A preparation method for multilayered quantum dot/silica/gadolinium compound/silica (QD/Si/Gd/Si) core–shell particles is proposed. Silica (Si)-coated quantum dot (QD/Si) core–shell particles were prepared by a Stöber method at room temperature in water/ethanol solution with TEOS and NaOH in the presence of QD nanoparticles. Succeeding gadolinium compound (Gd)-coating of the QD/Si core–shell particles was performed by a homogeneous precipitation method using Gd(NO₃)₃, urea, and polyvinylpyrrolidone in the presence of the QD/Si particles, which resulted in production of multilayered QD/silica/gadolinium compound (QD/Si/Gd) core–shell particles. For Si-coating of the QD/Si/Gd particles, the Stöber method was performed at room temperature in water/ethanol solution with TEOS and NaOH in the presence of the QD/Si/Gd particles. Consequently, Si-coated QD/Si/Gd, i.e., multilayered QD/Si/Gd/Si, core–shell particles were obtained. The QD/Si/Gd/Si particles revealed strong fluorescence, which was almost comparable to the QD particles with no shells. These particles are expected to be harmless to living bodies, and have dual functions of magnetic resonance imaging and fluorescence.     

Densities and Excess,Apparent, and Partial Molar Volumes of Binary Mixtures of BMIMBF<Subscript>4</Subscript> + Ethanol as a Function of Temperature,Pressure, and Concentration

The densities of five BMIMBF₄ (1-butyl-3-methylimidazolium tetrafluoroborate) + ethanol binary mixtures with compositions of (0.0701, 0.3147, 0.5384, 0.7452, and 0.9152) mole fraction BMIMBF₄ and of pure BMIMBF₄ have been measured with a vibrating-tube densimeter. Measurements were performed at temperatures from 298 K to 398 K and at pressures up to 40 MPa. The total uncertainty of density, temperature, pressure, and concentration measurements were estimated to be less than 0.1 kg · m⁻³, 15 mK, 5 kPa, and 10⁻⁴, respectively. The uncertainties reported in this article are expanded uncertainties at the 95% confidence level with a coverage factor of k = 2. The measured densities were used to study derived volumetric properties such as excess, apparent, and partial molar volumes. It is shown that the values of excess molar volume for BMIMBF₄ + ethanol mixtures are negative at all measured temperatures and pressures over the whole concentration range. The effect of water content on the measured values of density is discussed. The volumetric (excess, apparent, and partial molar volumes) and structural (direct and total correlation integrals, cluster size) properties of dilute BMIMBF₄ + ethanol mixtures were studied in terms of the Krichevskii parameter. The measured densities were used to develop a Tait-type equation of state.     

Effects of Cr,Mn, Si,Cu and Zr on microstructure and mechanical properties of high carbon Fe–16Al alloy

Abstract

Effects of alloying elements Cr, Mn, Si, Cu and Zr on the microstructure and mechanical properties of Fe₃Al (Fe–16Al) based alloy containing ～0·5 wt-%C have been investigated. Six alloys were prepared by a combination of air induction melting with flux cover and electroslag refining (ESR). ESR ingots were hot forged and hot rolled at 1373 K and were further characterised with respect to microstructure and mechanical properties. The base alloy and the alloys containing Cr, Mn, Si and Cu exhibit a two phase microstructure of Fe₃AlC_0·5 precipitates in Fe₃Al matrix whereas the alloy containing Zr exhibits a three phase microstructure, the additional phase being Zr rich carbide precipitates. Cr and Mn have high solubility in Fe₃AlC_0·5 precipitates as compared to Fe₃Al matrix whereas Cu and Si have very high solubility in Fe₃Al matrix compared to Fe₃AlC_0·5 precipitate and Zr has very low solubility in both Fe₃Al matrix and Fe₃AlC_0·5 precipitate. No significant improvement in room and high temperature (at 873 K) strengths was observed by addition of these alloying elements. Furthermore, it was observed that addition of these alloying elements has resulted in poor room and high temperature ductility. Addition of Cr, Mn, Si and Cu has resulted in marginal improvement in creep life, whereas Zr improved the creep life significantly from 22·3 to 117 h.     

Production, Properties and Applications of Bulk Amorphous Alloys

A review is given of recent work concerned with the production method, the characteristic properties(1) Bulk amorphous system; (2) Mechanical and magnetic properties of bulkamorphous alloys; (3)application of bulk amorphous alloys.     

The structure,modes of deformation and failure,and mechanical properties of diaminodiphenyl sulphone-cured tetraglycidyl 4,4′diaminodiphenyl methane epoxy

The tensile mechanical properties of diaminodiphenyl sulphone (DDS) — cured tetraglycidyl 4,4diaminodiphenyl methane (TGDDM) epoxies [TGDDM-DDS (12 to 35 wt% DDS)] are reported as a function of temperature and strain rate. TGDDM-DDS (20 to 35 wt% DDS) epoxies, which exhibit broadT _gs near 250° C, are not highly cross-linked glasses because diffusional and steric restrictions limit their cross-link density. TGDDM-DDS (10 to 20wt% DDS) epoxies are more brittle with lowerT _gs as a result of lower molecular weights and/or lower cross-link densities. Electron diffraction and X-ray emission spectroscopy studies indicate that TGDDM-DDS (>25wt% DDS) epoxies contain crystalline regions of unreacted DDS which can be eliminated from these epoxies during cure resulting in microvoids. TGDDM-DDS (12 to 35wt% DDS) epoxies predominantly deform and fail in tension by crazing, as indicated by fracture topography studies. These glasses also deform by shear banding as indicated by right-angle steps in the fracture topography initiation region and mixed modes of deformation that involve both crazing and shear banding. No evidence was found for heterogeneous cross-link density distributions in TGDDM-DDS (15 to 35wt% DDS) epoxies on straining films in the electron microscope.Research sponsored by the Air Force Office of Scientific Research/AFSC, United States Air Force, under Contract No. F44620-76-0075. The United States Government is authorized to reproduce and distribute preprints for governmental purposes notwithstanding any copyright notation hereon.National Science Foundation Faculty Research Participant: NSF Grant No. SER 76-04721.     

Refractivity virial coefficients and P, ρ, T data of ethylene

Virial coefficients for gaseous ethylene have been determined in the temperature range 283.15 to 373.15 K by means of a new refractive index P, , T method. Measurements of the pressure and temperature dependence of the refractive index n and the density and temperature dependence of (n — ****- 1) ^–1 were carried out by two coupled grating interferometers. From these interferometric measurements, we determined the refractivity virial coefficients A _R, B _R, and C_R of the Lorentz-Lorenz expansion, P, , T data, and the second and third virial coefficients B(T) and C(T) of the Leiden expansion. The deduced coefficients B(T) and C(T) are in excellent agreement with the accurate literature values.Paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 1988, Gaithersburg, Maryland, U.S.A.     

Mechanical processing,compaction, and thermal processing of α-Fe powder

High-energy ball milling is a proven technique for both mechanical alloying and for the production of nanocrystalline powders. In this U.S. Bureau of Mines study, it is found that mechanical processing pure α-Fe powders in a nitrogen environment results in nanocrystalline powders with nitrogen concentrations that increase linearly with time. In addition, processing in nitrogen results in a much smaller ultimate crystallite size than obtained in identical powders processed in argon. Consolidation of these powders by explosive compaction results in dense bodies that retain both their nanostructure and nitrogen content, whereas consolidation by HIPing results in retained nitrogen levels but a loss of nanostructure. Both the nanostructure and the high nitrogen levels of the explosively compacted materials are retained up to 863K.     

Effect of amount and atomic ratio of dual modifiers Ca and Mg on phase formation and mechanical properties of Ca,Mg-α-Sialons

Multi-cation -Sialons ceramics containing calcium and magnesium for the compositions ((Ca,Mg)_xSi_{12 – 3x}Al_3xO_xN_{16 – x}), where x equals 0.6 and 1.0 with the different atomic ratios of Ca to Mg, were fabricated by hot-pressing. An exploration for Ca,Mg--Sialon involving phase compositions, cell dimensions, microstructure and mechanical properties were carried out in the present work.