Secretion and secretory tissues of the anal sac of the mink,Mustela vison

The sulfur-rich anal sac secretion of the mink,Mustela vison, consisted of immiscible lipid (1.7% sulfur) and aqueous (0.7% sulfur) phases. Light and electron microscopy revealed secretory tissue of two types, sebaceous (holocrine) and apocrine. A major input of sulfur into the sac appeared to be associated with glycoprotein granules present in the apical portions of the apocrine cells as X-ray energy probe microanalysis showed these to contain relatively high levels of sulfur. The lipid of the secretion, presumed to be largely of sebaceous origin, consisted mainly of wax monoesters, while the aqueous phase contained volatile fatty acids, ammonia, and amines, including putrescine (1,4-diaminobutane). The identity of the major headspace volatiles was confirmed by NMR, MS, and Raney nickel desulfuration as being 2,2-dimethylthiacyclobutane and 3,3-dimethyl-1, 2-dithiacyclopentane. These compounds were not detected by GC-MS in the headspace volatiles of the anal sac secretions of eight other mustelid species examined. Other sulfur compounds detected included isomeric dimethylthiacyclobutanes, a number of disulfides and 3-methyl-but-3-enyl methyl sulfide (isopentenyl methyl sulfide). The significance of these findings is discussed.     

Analyzing the effect on heat transfer due to nonuniform distribution of liquid flow among the tubes of a shell-and-tube heat exchanger

A method is proposed using which nonuniform distribution of liquid flow among the tubes of a shell-and-tube apparatus can be taken into account by means of a statistical distribution function. A formula showing interrelation of this function with the indicator of heat transfer intensity in the apparatus tube space is given.     

Experimental Investigation and Thermodynamic Modeling of the ZrO2–SmO1.5 System

Phase equilibria of the ZrO₂–SmO_1.5 system have been studied by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The compositions of phases in the tetragonal+fluorite, fluorite+pyrochlore, and fluorite+B-Sm₂O₃ two-phase fields have been determined for samples quenched from temperatures between 1400° and 1700°C. The heat content of the fluorite phase with 30 mol% SmO_1.5 and of the pyrochlore phase with 50 mol% SmO_1.5 has been measured in the temperature range 200°–1400°C using high-temperature drop calorimetry. The transition between pyrochlore and fluorite phases is clearly first order in the SmO_1.5-rich region, while no fluorite+pyrochlore two-phase region has been detected for the samples with ZrO₂ excess. Based on the obtained experimental results and literature data, the phase diagram and thermodynamic properties were optimized using the CALPHAD approach.     

Experimental study and thermodynamic modelling of the ZrO2–LaO1.5 system

Phase relations in the ZrO₂–LaO_1.5 system were studied experimentally in the temperature range from 1673 to 1973 K. X-ray diffraction and scanning electron microscopy were employed to obtain the structural information and the compositions of the tetragonal and pyrochlore (La₂Zr₂O₇) phases. The solubility of LaO_1.5 in the tetragonal phase was determined to be very small. The homogeneity range of the pyrochlore phase is estimated to be less than 2 mol% at 1973 K, and less than 1 mol% at 1673 K according to the present work. Based on the experimental results obtained in this work, as well as the available phase diagram and thermodynamic data in literature, a self-consistent thermodynamic assessment was carried out by using the ionic sublattice solution model.     

Optimal rotation deceleration of a dynamically symmetric body with movable mass in a resistant medium

A minimum-time problem on deceleration of rotation of a free rigid body is studied. The body is assumed to contain a viscous-elastic element, which is modeled as a movable point mass attached to the body via a damper. In addition, the body is subjected to a retarding torque generated by linear medium resistance forces. In an undeformed state, the body is assumed to be dynamically symmetric, with the mass being located on the symmetry axis. An optimal control law for deceleration of rotation of the body is synthesized, and the corresponding time and phase trajectories are determined.     

Assessment techniques,database design and software facilities for thermodynamics and diffusion

The purpose of this article is to give a set of recommendations to producers of assessed thermodynamic data, who may be involved in either the critical evaluation of limited chemical systems or the creation and dissemination of larger thermodynamic databases. Also, it is hoped that reviewers and editors of scientific publications in this field will find some of the information useful. Good practice in the assessment process is essential, particularly as datasets from many different sources may be combined together into a single database. With this in mind, we highlight some problems that can arise during the assessment process and we propose a quality assurance procedure. It is worth mentioning at this point, that the provision of reliable assessed thermodynamic data relies heavily on the availability of high quality experimental information. The different software packages for thermodynamics and diffusion are described here only briefly.