PVT properties of concentrated aqueous electrolytes. III. Volume changes for mixing the major sea salts at I=1.0 and 3.0 at 25°C

The densities of mixtures of the six possible combinatons of the major sea salts (NaCl, Na₂SO₄, MgSO₄, and MgCl₂) were determined at constant ionic strengths of I=1.0 and I=3.0 at 25°C. The results are used to determine the volume changes for mixing (V _m ) the major sea salts. The values of V _m were fit to equations of the form V _m where y _i is the molal ionic strength fraction of solute i, and ₀ and ₁ are parameters related to the interaction of like-charged ions. The cross-square rule was found to hold at both ionic strengths. Density estimates were made without and with the addition of volume of mixing terms to Young's Rule and compared to the experimental values. The densities calculated with the addition of volume of mixing terms gave better estimates, demonstrating that the densities of concentrated brines can be more accurately estimated using V _m terms. The equations of Reilly and Wood which include the cross-square rule were used to estimate the densities of the cross mixtures (NaCl–MgSO₄ and MgCl₂–Na₂SO₄). The estimated densities agree with the measured values to within ±30 ppm at I=1.0 and ±125 ppm at I=3.0.     

Tunable laser study of the ν10 + ν11 band of cyclopropane

Diode laser measurements of the ν₁₀ + ν₁₁ (l_tot = ±2) perpendicular band of cyclopropane have led to the assignments of roughly 600 lines in the 1880–1920-cm^?1 region. Most of the spectra were recorded and stored in digital form using a rapid-scan mode of operating the laser. These spectra were calibrated, with the aid of a computer, by reference to the R lines of the ν₁ + ν₂ band of N₂O. The ground state constants we obtained are (in cm^?1) B = 0.670240 ± 2.4 × 10^?5, D_J = (1.090 ± 0.054) × 10^?6, D_JK = (?1.29 ± 0.19) × 10^?6, D_K = (0.2 ± 1.1) × 10^?6. The excited state levels are perturbed at large J values, presumably by Coriolis couplings between the active E′(l_tot = ±2) and the inactive A′(l_tot = 0) states. Effective values for the excited state constants were obtained by considering only the J < 15 levels. The A₁-A₂ splittings in the K′ = 1 excited states were observed to vary as q_effJ(J + 1), with q_eff = (2.17 ± 0.17) × 10^?4 cm^?1.     

The role of 18-methyleicosanoic acid in the structure and formation of mammalian hair fibres

Although branched chain fatty acids perform many functions in biological systems, the importance of the anteiso 18 methyleicosanoic acid (MEA) has only recently been recognized. In this first review on MEA its role and distribtuion is explored MEA has been found in minor amounts in the fatty acid components of a wide range of biological materials, but the current interest results from it being the major covalently bound fatty acid in mammalian hair fibres, a finding which is unusual because protein-bound fatty acids are typically straight-chain, even-numbered acids (C14–C18). MEA is released by surface restricted reagents indicating that it is located exclusively in or on the surface of the cuticle cells, a conclusion that has been verified by analysis of isolated cuticle cells. X-ray photoelectron spectroscopy (XPS) and secondary-ion mass spectroscopy (SIMS) studies support these results in that they show the surface of the cuticle to be predominantly hydrocarbon. When either neutral hydroxylamine or acidic chlorine solutions are applied to hair and wool fibres fatty acids are liberated, indicating the presence of thioester bonds. Calculations, based on fatty acid and amino acid analysis, indicate that approximately one residue in 10 of the cuticular membrane protein is a fatty acid thioester of cysteine. Removal of this covalently linked fatty acid renders the fibre hydrophilic, thus offering a chemical explanation for many technological and cosmetic treatments of mammalian fibres. Examination of the fibre surface and that of isolated cuticle cells by transmission electron microscopy (TEM) confirms the presence of a thin non-staining continuous layer surrounding the cuticle cells. Alkaline treatments which remove the bound fatty acids were found to disrupt this layer. TEM examination of developing hair fibres has indicated that the fatty acid layer on the upper surface and scale edges of the cuticle cell differs from that of the underside of the cell. Similar structural studies of hair from patients with maple syrup urine disease (MSUD) support the findings that thioester-bound MEA is limited to the upper surface of fibre cuticle cells. The current model proposed for the boundary layer consists of crosslinked protein with surface thioester-linked fatty acids. forming a continuous hydrophobic layer on the upper surface and scale edges of the cells.     

Synthesis of 4″-carboxylated cannabinoids: Stereospecific processes involving ethylidenemalonic ester

4″-Carboxylated-cannabidiol,-Δ¹-and-Δ^1,6-tetrahydrocannabinols and - cannabinol are synthesised. Condensation between aromatic aldehydes and ethylidenemalonic ester gives a 2$\text{E}$,4$\text{E}$-half ester stereospecifically, a reaction which can be used to make 2$\text{E}$-4$\text{E}$- or 2$\text{Z}$,4$\text{E}$-pentadienoates.     

Studies of luminol-dependent whole-blood chemiluminescence induced by platelet-activating factor (PAF)

A whole-blood luminol-dependent chemiluminescence (CL) assay stimulated by platelet-activating factor (PAF) is reported. Factors investigated using this assay were dilution of blood, dose responsiveness of PAF, and inactivation of PAF. The final conditions chosen for the assay were a 1:10 dilution of whole blood and 2 × 10^?4M luminol. Nordihydroguaiaretic acid (NDGA) and indomethacin (INDO), which inhibit lipoxygenase and cyclooxygenase, decreased luminol-dependent whole-blood chemiluminescence by 59 and 17%, respectively. Superoxide dismutase and catalase were relatively ineffective inhibitors of CL (28 and 22%, respectively) while sodium azide was most inhibitory (84%). Although these studies were not entirely conclusive, lipoxygenase and myeloperoxidase appear to be important in CL elicited by PAF in this whole-blood CL assay. This system may serve as a useful screening system for measuring the effect of PAF in the blood of different individuals without extensive separation of cell types. It has the distinct advantage of being closer to in situ Conditions.     

Search for rare and forbidden Charm Meson decays D0 --> Vl+l- and hhll

We report results of a search for flavor-changing neutral current (FCNC), lepton flavor, and lepton-number violating decays of the D0 (and its antiparticle) into three and four bodies. Using data from Fermilab charm hadroproduction experiment E791, we examine modes with two leptons (muons or electrons) and a rho(0), K( *0), or straight phi vector meson or a nonresonant pi(pi), Kpi, or KK pair of pseudoscalar mesons. No evidence for any of these decays is found. Therefore, we present branching-fraction upper limits at 90% confidence level for the 27 decay modes examined (18 new).