The corrosion-electrochemical behavior of the PT-7M titanium alloy after oxynitriding

The corrosion-electrochemical behavior of the PT-7M titanium alloy after oxynitriding in a 0.9% aqueous solution of sodium chloride is investigated. Oxynitriding is performed by modifying the oxygen of the nitride layer formed upon thermal-diffusion saturation in the atmosphere of molecular nitrogen. It is established that the protective properties of the alloy are determined by the quantitative ratio of the oxynidride and oxide phases in the modified surface layer. It is shown that, as the content of the oxynitride phase in the composition of the surface layer increases and the oxygen component in its composition decreases, the anticorrosion characteristics of the alloy surface are improved.     

Control of Length of Concrete Piles in Soil by the Acoustic Probing Method

The prototype of portable device is developed and approved for probing the concrete piles located in soil. The procedure for determining the pile length is proposed.     

Immature Vascular Smooth Muscle Cells in Healthy Murine Arteries and Atherosclerotic Plaques: Localization and Activity

The local development of atherosclerotic lesions may, at least partly, be associated with the specific cellular composition of atherosclerosis-prone regions. Previously, it was demonstrated that a small population of immature vascular smooth muscle cells (VSMCs) expressing both CD146 and neuron-glial antigen 2 is postnatally sustained in atherosclerosis-prone sites. We supposed that these cells may be involved in atherogenesis and can continuously respond to angiotensin II, which is an atherogenic factor. Using immunohistochemistry, flow cytometry, wound migration assay xCELLigence system, and calcium imaging, we studied the functional activities of immature VSMCs in vitro and in vivo. According to our data, these cells do not express nestin, CD105, and the leptin receptor. They are localized in atherosclerosis-prone regions, and their number increases with age, from 5.7% to 23%. Immature VSMCs do not migrate to low shear stress areas and atherosclerotic lesions. They also do not have any unique response to angiotensin II. Thus, despite the localization of immature VSMCs and the presence of the link between their number and age, our study did not support the hypothesis that immature VSMCs are directly involved in the formation of atherosclerotic lesions. Additional lineage tracing studies can clarify the fate of these cells during atherogenesis.     

Using ELP Repeats as a Scaffold for De Novo Construction of Gadolinium-Binding Domains within Multifunctional Recombinant Proteins for Targeted Delivery of Gadolinium to Tumour Cells

Three artificial proteins that bind the gadolinium ion (Gd³⁺) with tumour-specific ligands were de novo engineered and tested as candidate drugs for binary radiotherapy (BRT) and contrast agents for magnetic resonance imaging (MRI). Gd³⁺-binding modules were derived from calmodulin. They were joined with elastin-like polypeptide (ELP) repeats from human elastin to form the four-centre Gd³⁺-binding domain (4MBS-domain) that further was combined with F3 peptide (a ligand of nucleolin, a tumour marker) to form the F3-W4 block. The F3-W4 block was taken alone (E2-13W4 protein), as two repeats (E1-W8) and as three repeats (E1-W12). Each protein was supplemented with three copies of the RGD motif (a ligand of integrin αvβ3) and green fluorescent protein (GFP). In contrast to Magnevist (a Gd-containing contrast agent), the proteins exhibited three to four times higher accumulation in U87MG glioma and A375 melanoma cell lines than in normal fibroblasts. The proteins remained for >24 h in tumours induced by Ca755 adenocarcinoma in C57BL/6 mice. They exhibited stability towards blood proteases and only accumulated in the liver and kidney. The technological advantages of using the engineered proteins as a basis for developing efficient and non-toxic agents for early diagnosis of tumours by MRI as well as part of BRT were demonstrated.     

Identification of 130 kDa cell surface LDL-binding protein from smooth muscle cells as a partially processed T-cadherin precursor

Atypical cell surface lipoprotein-binding proteins of 105 kDa and 130 kDa are present in membranes of vascular smooth muscle cells. We recently identified the 105 kDa protein from human aortic media as T-cadherin, an unusual glycosylphosphatidylinositol (GPI)-anchored member of the cadherin family of cell adhesion proteins. The goal of the present study was to determine the identity of 130 kDa lipoprotein-binding protein of smooth muscle cells. We applied different approaches that included protein sequencing of purified protein from human aortic media, the use of human T-cadherin peptide-specific antisera, and enzymatic treatment of cultured cells with trypsin and GPI-specific phospholipase C. Our results indicate that the 130 kDa protein is a partially processed form of T-cadherin which is attached to the membrane surface of smooth muscle cells via a GPI anchor and contains uncleaved N-terminal propeptide sequence. Our data disclose that, in contrast to classical cadherins, T-cadherin is expressed on the cell surface in both its precursor (130 kDa) and mature (105 kDa) forms.     

Low-temperature time-resolved photoluminescence in InGaN/GaN quantum wells

The results of the investigation of low-temperature time-resolved photoluminescence in undoped and Si-doped In_0.2Ga_0.8N/GaN structures, which contain 12 quantum wells of width 60 Å separated by barriers of width 60 Å, are reported. The structures were grown by the MOCVD technique on sapphire substrates. The photoluminescence properties observed are explained by the manifestation of two-dimensional donor-acceptor recombination. These properties are the high-energy shift of the peak upon increasing the pumping intensity, a low-energy shift with increasing delay time, and a power law of luminescence decay of the t ^-γ type. The estimates of the total binding energy for donor and acceptor centers are given. This energy is 340 and 250 meV for Si-doped and undoped quantum wells, respectively. The role of the mosaic structure, which is typical for Group III hexagonal nitrides, is discussed as a factor favorable for the formation of donor-acceptor pairs.