Features of aeolian relief formation of the sandy massif Suvinskii Kuitun in the Barguzin Depression

The principal objective of the article is the determination of the main features of the aeolian relief formation of the Suvinskii Kuitun sand massif, one of the regions of active modern aeolian morphogenesis in the Barguzinskaya Depression. A brief description of the morphology of the aeolian relief, characterized by the predominance of deflationary forms over accumulative ones, is given. Among the forms of active deflation, deflation basins dominate here, separated by elongated deflation inselbergs, composed of sands of lacustrine, alluvial, deluvial-proluvial, and aeolian genesis. The mineralogical and granulometric composition of sandy deposits in the southern part of the Suvinskii Kuitun, characterized by poor roundness of sandy grains, has been analysed. A distinct northeastward eolomotion was revealed towards the foothills of the Ikat Range and its accumulation there. The age of the aeolian sands, mainly related to the formation of the Tagar culture (the end of the Bronze Age) was determined. The phytomelioration carried out in the second half of the 20th century led only to a partial fixation of sands, without affecting their overall deflation in most areas of the Suvinskii Kuitun.

Evaluation of Round Window Stimulation Performance in Otosclerosis Using Finite Element Modeling

Round window (RW) stimulation is a new type of middle ear implant’s application for treating patients with middle ear disease, such as otosclerosis. However, clinical outcomes show a substantial degree of variability. One source of variability is the variation in the material properties of the ear components caused by the disease. To investigate the influence of the otosclerosis on the performance of the RW stimulation, a human ear finite element model including middle ear and cochlea was established based on a set of microcomputerized tomography section images of a human temporal bone. Three characteristic changes of the otosclerosis in the auditory system were simulated in the FE model: stapedial annular ligament stiffness enlargement, stapedial abnormal bone growth, and partial fixation of the malleus. The FE model was verified by comparing the model-predicted results with published experimental measurements. The equivalent sound pressure (ESP) of RW stimulation was calculated via comparing the differential intracochlear pressure produced by the RW stimulation and the normal eardrum sound stimulation. The results show that the increase of stapedial annular ligament and partial fixation of the malleus decreases RW stimulation’s ESP prominently at lower frequencies. In contrast, the stapedial abnormal bone growth deteriorates RW stimulation’s ESP severely at higher frequencies.

Meniscal allograft transplantation in rabbit

This study evaluated the technique for meniscal allograft transplantation using allografts preserved in glycerin 98% in rabbits. Euthanasia was performed at 70 days to compare the transplanted (TM1 to TM16) versus the contralateral meniscus (OM1 to OM16). Sixteen menisci, 8 transplanted and 8 contralateral, were submitted to gross examination, histomorphometric analysis for identification and quantification of cellular type, and for quantification and distribution of collagen fibers. A revascularization study was conducted in all of the other samples. Lengths of the OM varied from 0.9 to 1.0 cm and two TM were smaller. All TM were completely attached to the synovial membrane, except for one case that presented partial fixation. Both, TM and OM had similar amounts of chondrocytes, fibroblasts and fibrocytes, and at the horns, chondrocytes were predominant. The collagen fibers in TM were well organized throughout the body, and disorganized at the horns. These fibers in OM were organized. The amounts of collagen type I and III, and the vascularization of the perimeniscal tissue and of the edge were similar in OM and TM. These results demonstrated graft integration and thus this transplantation technique and preservation method may be recommended.

Biologically induced precipitation in urine-collecting systems

Precipitation in urine-separating toilets (NoMix toilets), waterless urinals, and conventional urinals causes severe maintenance problems. Additionally, the partial fixation of nutrients in precipitates may affect the later use and treatment of source-separated urine. The goal of this study was to characterise the mineral composition of the precipitates and to identify the main causes for precipitation. X-ray diffraction analysis showed that the main crystalline compounds are struvite, hydroxyapatite, and calcite. We measured concentrations in the solutions of the traps and of the urine collection tank for estimating saturation indices, extent of urea degradation, urine dilution, and elimination of solutes. Our results indicate that bacterial urea degradation triggers precipitation. The composition of the precipitates depends on the urine dilution with flushing water: in low diluted urine, struvite is the main compound, while calcite dominates in systems with high urine dilution. HAP occurs over a wide range of dilution factors. A high fraction of phosphate is incorporated into the precipitates. Dilution with tap water increases this fraction by providing the limiting calcium and magnesium ions. Currently, constructing exchangeable traps seems to be the best solution to deal with problematic precipitation.

Conformational aspects of N-glycosylation of proteins. Studies with linear and cyclic peptides as probes

Conformational aspects of N-glycosylation of glycoproteins have been studied by using a series of peptides which contained, in addition to the ‘marker sequence’ Asn-Gly-Thr, two cysteine residues in various positions of the peptide chain. The presence of two cysteines permitted a partial fixation of the above triplet sequence in cyclic structures of various size by intramolecular disulphide bond formation. Comparison of the glycosyl acceptor properties of the linear peptides and their corresponding cyclic analogues allows the following statements. The considerably lower acceptor capabilities of the cyclic derivatives indicate that the restriction of rotational degrees of freedom imposed by disulphide bonding results in a conformation which hinders a favourable interaction of the peptide substrate with the N-glycosyltransferase. On the other hand, the glycosylation rate of linear peptides increases with increasing chain length, suggesting that the amino acids on both the N- and C-terminal side of the ‘marker sequence’ may contribute to a considerable extent to the induction of an ‘active’ conformation. Realization of a potential sugar attachment site requires a hydrogen bond interaction within the ‘marker sequence’ between the oxygen of threonine (serine) as the hydrogen bond acceptor and the β-amide of asparagine as the donor [Bause & Legler (1981) Biochem. J.195, 639–644]. This interaction is obviously facilitated when the peptide chain can adopt a conformation which resembles a β-turn or other loop structure. The available experimental and statistical data are discussed in terms of possible structural features for N-glycosylation, with the aid of space-filling models.

Centrifugal method of determining red cell deformability

A recently developed technique for deforming red blood cells (RBC) in which they are centrifuged through buffer and into a glutaraldehyde solution was evaluated as a method of assessing cellular deformability (i.e., the ability of the entire RBC to form a new configuration). To accomplish this, RBC populations of differing cellular deformability were tested, using three generally accepted techniques to obtain these differences: partial fixation with low concentrations of glutaraldehyde, density fractionation, and suspension of RBC in nonisotonic media. Our results indicate that at a constant deforming force the mean deformed length of the RBC decreased under conditions where cellular deformability is known to decrease, thus suggesting the usefulness of this centrifugal method for the estimation of this cellular property.