Decentration and stress and strain state in hip joint of patients with dysplasia of the hip

Abstract Purpose of the study: to find a correlation between radiological and biomechanical parameters of a hip joint (HJ) in case of dysplastic instability for dystrophic process in the joint study. Materials and methods. Clinical and radiological data of 154 patients aged from 2 to 13 years with dysplastic instability of a HJ the development of which was being observed from 2 to 5 years (189 joints) were studied. The following parameters of a HJ were determined: acetabular index, cervico-diaphyseal angle, centration of the femoral head. All the measurements were performed by plain pelvis radiographs without special positioning the patient. The stress and strain state in the acetabulum and proximal part of the femur was studied using the finite element method. The stress intensity (stress of von Mises, measured in MPa) was chosen as a basic characteristic, which is one of the most informative one for the stress and strain state evaluation. Results. The study has shown that of the three types of decentration such as coaxial, non-coaxial with downward and lateral acetabular center displacement from a HJ center, non-coaxial with downward and medial acetabular center displacement, the last-mentioned has turned out to be less favorable. Moreover, an increased angle of deviation corresponded to greater width and sclerosis intensity of a HJ subchondral surface and also fragmentation of the femoral head was observed in the majority of cases. Studied stress and strain state in a HJ has revealed that decentration in a joint is a key factor, which leads to osteartrosis development. The large decentration, the more severe stress intensity at the lower part of the femoral head and at the upper border of the acetabulum was. Thus, the value of stress intensity at the upper part of the femoral head decreased and was 2.3 MPa comparing with the normal one 2.5 MPa; at the lower part it increased to 2.3 MPa, that was twice higher than the normal one. On the front edge of the acetabulum the stress state level was about 2.3 MPa, which was almost four times more than the normal one (0,6 MPa) in this region. Increase in acetabulum curvature didn’t change the pattern of stress and strain state distribution, but it led to increase in strain level especially at the posterior superior part of the acetabulum and, respectively, at the contact region of the femoral head. Conclusions. The femoral head rotational center shift changes the pattern of stress and strain state distribution in a HJ in comparison with the norms, increases the stress at its lower part and also increases stress state at the upper acetabular edge. Increase in acetabulum curvature doesn’t change the pattern of stress and strain state distribution, but it leads to increase in strain level especially at the acetabular posterior superior part and, respectively, at the contact region of the femoral head. Decentration of HJ elements is the main etiological factor of its instability leading to the further dystrophic transformation of the joint. Biomechanic modeling of decentration in a HJ using the finite element method has proved the fact of complex changes in HJ structures at the early stages of the pathological process development, revealed understanding of the decentration process in a joint, contributed to working out the dystrophic process early prevention and treatment tactics

Recent Progress in the Membrane Distillation and Impact of Track-Etched Membranes

Membrane distillation (MD) is a rapidly developing field of research and finds applications in desalination of water, purification from nonvolatile substances, and concentration of various solutions. This review presents data from recent studies on the MD process, MD configuration, the type of membranes and membrane hydrophobization. Particular importance has been placed on the methods of hydrophobization and the use of track-etched membranes (TeMs) in the MD process. Hydrophobic TeMs based on poly(ethylene terephthalate) (PET), poly(vinylidene fluoride) (PVDF) and polycarbonate (PC) have been applied in the purification of water from salts and pesticides, as well as in the concentration of low-level liquid radioactive waste (LLLRW). Such membranes are characterized by a narrow pore size distribution, precise values of the number of pores per unit area and narrow thickness. These properties of membranes allow them to be used for more accurate water purification and as model membranes used to test theoretical models (for instance LEP prediction). © 2021 by the authors. Licensee MDPI, Basel, Switzerland.This research was funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan (Grant No. AP09057934)

Experimental study of direct photon emission in K- --> pi- pi0 gamma decay using ISTRA+ detector

The branching ratio in the charged-pion kinetic energy region of 55 to 90 MeV for the direct photon emission in the K- --> pi- pi0 gamma decay has been measured using in-flight decays detected with the ISTRA+ setup operating in the 25 GeV/c negative secondary beam of the U-70 PS. The value Br(DE)=[0.37+-0.39(stat)+-0.10(syst)]*10^(-5) obtained from the analysis of 930 completely reconstructed events is consistent with the average value of two stopped-kaon experiments, but it differs by 2.5 standard deviations from the average value of three in-flight-kaon experiments. The result is also compared with recent theoretical predictions.Comment: 13 pages, 8 figure

Polymeric hybrid iodoplumbates and iodobismuthates containing mono- and bisalkylated derivatives of 1,2-bis(4-pyridyl)ethylene: Structural and optical features

© 2017 Elsevier B.V.Reactions of PbI2 with N-alkylated derivatives of 1,2-bis(4-pyridyl)ethylene (bpen) MeBpenI and Me2BpenI2 result in 1D-polymeric complexes [{Pb(MeBpen)I3}] (1) and (Me2bpen)[{PbI3}]2 (2). For both compounds, band gap values were determinated experimentally; 1 demonstrates weak red luminescence. Binuclear hybrid iodobismuthate [Bi2(MeBpen)2I8] (3) was obtained by the similar scheme using BiI3 instead of PbI2

Modification of pet ion-track membranes by silica nanoparticles for direct contact membrane distillation of salt solutions

The paper describes desalination by membrane distillation (MD) using ion-track membranes. Poly(ethylene terephthalate) (PET) ion-track membranes were hydrophobized by the immobilization of hydrophobic vinyl-silica nanoparticles (Si NPs). Si NPs were synthesized by the sol-gel method, and the addition of the surfactant led to the formation of NPs with average size of 40 nm. The thermal initiator fixed to the surface of membranes allowed attachment of triethoxyvinyl silane Si NPs at the membrane surface. To further increase hydrophobicity, ethoxy groups were fluorinated. The morphology and chemical structure of prepared membranes were characterized by SEM, FTIR, XPS spectroscopy, and a gas permeability test. Hydrophobic properties were evaluated by contact angle (CA) and liquid entry pressure (LEP) measurements. Membranes with CA 125–143◦ were tested in direct contact membrane distillation (DCMD) of 30 g/L saline solution. Membranes showed water fluxes from 2.2 to 15.4 kg/(m2·h) with salt rejection values of 93–99%. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.The research titled “Preparation of track-etched membranes with specified properties for membrane distillation and forward osmosis” (grant No AP05132110) was funded by the Ministry of Education and Science of the Republic of Kazakhstan