Single-turn Coils for Magnetic Pulse Welding of High-strength Steel Parts

Magnetic pulse welding provides high quality joining of fuel pin cladding for fast nuclear reactors. The tool coil there operates under the most stressful conditions: 40 T magnetic fields with tens of microseconds duration. This requires minimal coil inductance and affects the capabilities and lifetime of the coils. Two approaches are being practiced to enhance the coil durability: material research and construction optimization. The first approach considers the use of high strength steels or composite materials for the coil working area. The present work is aimed to realize the second approach – the use of multi position coils in order to maximize the number of parts welded in one coil. Experiments and finite element modeling were carried out for two designs of two- and four-position single-turn coils, which were made to process several workpieces in one current pulse. The main parameters measured and calculated were the magnetic field between the coil and the workpiece, and the ratio of its amplitude to the discharge current, Bm/Im. The currents flowing through the coils were about 700 kA, which correspond to the magnetic fields of 40–45 T. The FEM modeling revealed a 17–19% drop of the magnetic induction near the insulated slit, which, however, did not prevent the helium-tight joining of the tubes to the end plugs

Spectral studies of the dithiacrown ether derivative in the presence of metal cations and modeling their possible complexes

© ISUCT Publishing. The preparation of compositions comprising multifunctional compound is one of the key directions for design of chemosensoring materials that are important for the determination of particular ions in solutions. These compounds are characterized by ionophoric and photosensitive parts with reliable optical response and ion-selectivity. Their structures suggest the possibility of the complex formation with particular metal cations. The main goals of this study are as following: a) to investigate the absorption spectra of the novel derivative of the dithiacrown ethers (DTCE), synthesized in the laboratory of Professor S.P. Gromov (Photochemistry Center RAS), both: in salt solutions and in monolayers; b) to study the DTCE interaction with various metal cations, including mercury, as well as to carry out quantum-chemical calculations of their possible complexes. Spectral characteristics were examined in the DTCE acetonitrile solutions and their changes in the presence of some cations were found. The pronounced changes were obtained in the case of Hg2+ which are expressed as a hypsochromic shift on 22 nm. Absorption spectra of aqueous solutions of DTCE and perchlorates of alkali, alkaline earth, and heavy metals (lithium, sodium, potassium, cesium, magnesium, calcium, strontium, barium, copper, zinc, lead, cadmium, and mercury) at various concentrations were obtained. When the DTCE concentration equals to 10–5 M, the absorption intensity is low, and DTCE absorption maximum shifts in the presence of all the salts are rather small. The greatest shift (by 6 nm) of the DTCE absorption maximum to shorter wavelengths was observed for the mercury(II) perchlorate only. In order to select the DTCE concentration for further research the spectral dependence of the optical density vs. DTCE concentration was obtained (10 M was the most appropriate value of the DTCE concentration). Based on these results the DTCE extinction coefficient in aqueous solutions was determined (ε = 9329 M–1cm–1). Assuming the formation of the DTCE-cation complexes as 1:1, the metal perchlorates with lack and excess of the cations in the aqueous solutions were chosen. The absorption spectra had minor differences at DTCE concentration of 10–4 M and metal perchlorates concentration of 10–5 M (lack of the metal cations). Maximum hypsochromic shift by 4 nm was observed in the presence of mercury(II) perchlorate. It appeared that the lack of concentration of the metal salt does not allow the formation of complexes between the crown ether ring and a cation. The absorption intensity in the presence of most of salts was slightly reduced up to 85–95 % from baseline. The absorption spectra showed significant shifts of the absorption maxima to shorter wavelengths by 29 nm only in the presence of mercury(II) perchlorate at high concentrations (10–3 M). This fact proves a DTCE selectivity for mercury(II) cation. Moreover, the value of the shift depends on the salt concentration. An additional confirmation of these results was obtained in the study of the absorption spectra of the DTCE monolayers transferred from bidistilled water and aqueous solutions of Hg(ClO4)2 at constant surface pressure (about 10 mN/m). In all cases, the broad absorption maxima in the region of 350–450 nm were found. The main feature was that the maximum absorption for DTCE monolayer transferred to 10–5 M solution of Hg(ClO4)2 was 0.00575 a.u. at 406 nm. This is by 209% higher than those for the DTCE monolayer transferred from the water. Thus, the shift of the absorption maximum of DTCE monolayer in the presence of mercury salt was 23 nm to shorter wavelengths. This is further evidence of complex formation between DTCE (in monolayer) and mercury(II) cations from the aqueous subphase. For visualization and confirmation of the possibility of complex formation between DTCE and mercury(II) cation the quantum-chemical calculations of their structural models were carried out. The total energy of the optimized structure of the complex between DTCE cation and mercury(II) (with 2 perchlorate counter-anions) is set to E0 = –565.1231 a.u. It can be compared with the energies of individual species: the DTCE cation (E0 = –250.5477 a.u.) and Hg(ClO4)2 (E0 = –314.4877 a.u.). Thus, the change in energy (ΔE) upon complex formation is about –0.0877 a.u. (–230 kJ/mol). High energy of complex formation and high covalency of the Hg–S bonds explain the significant blue shift of the maximum in the absorption spectra of the solutions of DTCE with Hg(ClO4)2

Study of a Material Based on a Nanostructured Copper-Niobium Alloy for the Development of Magnetic Pulse Tools

The results of study of samples made of finely dispersed Cu-Nb by powder method are given. Comparative tests of materials stability under the generation of magnetic fields up to 40 Tl of microsecond duration are carried out.Работа выполнена при частичном финансировании грантов РФФИ (20-58-00029 Бел_а, 20-21-00050 Росатом)

2020 Clinical practice guidelines for Hypertrophic cardiomyopathy

Russian Society of Cardiology (RSC)With the participation: Russian Association of Cardiovascular SurgeonsEndorsed by: Research and Practical Council of the Ministry of Health of the Russian Federation Task Force: Gabrusenko S.A. (Chairman), Gudkova A.Ya.* (Chairman), Koziolova N.A. (Chairman), Alexandrova S.A., Berseneva M.I., Gordeev M.L., Dzemeshkevich S.L., Zaklyazminskaya E.V., Irtyuga O.B., Kaplunova V.Yu., Kostareva A.A., Krutikov A.N., Malenkov D.A., Novikova T.N., Saidova M.A., Sanakoev M.K., Stukalova O.V

Case Reports1. A Late Presentation of Loeys-Dietz Syndrome: Beware of TGFβ Receptor Mutations in Benign Joint Hypermobility

Background: Thoracic aortic aneurysms (TAA) and dissections are not uncommon causes of sudden death in young adults. Loeys-Dietz syndrome (LDS) is a rare, recently described, autosomal dominant, connective tissue disease characterized by aggressive arterial aneurysms, resulting from mutations in the transforming growth factor beta (TGFβ) receptor genes TGFBR1 and TGFBR2. Mean age at death is 26.1 years, most often due to aortic dissection. We report an unusually late presentation of LDS, diagnosed following elective surgery in a female with a long history of joint hypermobility. Methods: A 51-year-old Caucasian lady complained of chest pain and headache following a dural leak from spinal anaesthesia for an elective ankle arthroscopy. CT scan and echocardiography demonstrated a dilated aortic root and significant aortic regurgitation. MRA demonstrated aortic tortuosity, an infrarenal aortic aneurysm and aneurysms in the left renal and right internal mammary arteries. She underwent aortic root repair and aortic valve replacement. She had a background of long-standing joint pains secondary to hypermobility, easy bruising, unusual fracture susceptibility and mild bronchiectasis. She had one healthy child age 32, after which she suffered a uterine prolapse. Examination revealed mild Marfanoid features. Uvula, skin and ophthalmological examination was normal. Results: Fibrillin-1 testing for Marfan syndrome (MFS) was negative. Detection of a c.1270G > C (p.Gly424Arg) TGFBR2 mutation confirmed the diagnosis of LDS. Losartan was started for vascular protection. Conclusions: LDS is a severe inherited vasculopathy that usually presents in childhood. It is characterized by aortic root dilatation and ascending aneurysms. There is a higher risk of aortic dissection compared with MFS. Clinical features overlap with MFS and Ehlers Danlos syndrome Type IV, but differentiating dysmorphogenic features include ocular hypertelorism, bifid uvula and cleft palate. Echocardiography and MRA or CT scanning from head to pelvis is recommended to establish the extent of vascular involvement. Management involves early surgical intervention, including early valve-sparing aortic root replacement, genetic counselling and close monitoring in pregnancy. Despite being caused by loss of function mutations in either TGFβ receptor, paradoxical activation of TGFβ signalling is seen, suggesting that TGFβ antagonism may confer disease modifying effects similar to those observed in MFS. TGFβ antagonism can be achieved with angiotensin antagonists, such as Losartan, which is able to delay aortic aneurysm development in preclinical models and in patients with MFS. Our case emphasizes the importance of timely recognition of vasculopathy syndromes in patients with hypermobility and the need for early surgical intervention. It also highlights their heterogeneity and the potential for late presentation. Disclosures: The authors have declared no conflicts of interes

Spectral studies of the dithiacrown ether derivative in the presence of metal cations and modeling their possible complexes

© ISUCT Publishing. The preparation of compositions comprising multifunctional compound is one of the key directions for design of chemosensoring materials that are important for the determination of particular ions in solutions. These compounds are characterized by ionophoric and photosensitive parts with reliable optical response and ion-selectivity. Their structures suggest the possibility of the complex formation with particular metal cations. The main goals of this study are as following: a) to investigate the absorption spectra of the novel derivative of the dithiacrown ethers (DTCE), synthesized in the laboratory of Professor S.P. Gromov (Photochemistry Center RAS), both: in salt solutions and in monolayers; b) to study the DTCE interaction with various metal cations, including mercury, as well as to carry out quantum-chemical calculations of their possible complexes. Spectral characteristics were examined in the DTCE acetonitrile solutions and their changes in the presence of some cations were found. The pronounced changes were obtained in the case of Hg2+ which are expressed as a hypsochromic shift on 22 nm. Absorption spectra of aqueous solutions of DTCE and perchlorates of alkali, alkaline earth, and heavy metals (lithium, sodium, potassium, cesium, magnesium, calcium, strontium, barium, copper, zinc, lead, cadmium, and mercury) at various concentrations were obtained. When the DTCE concentration equals to 10–5 M, the absorption intensity is low, and DTCE absorption maximum shifts in the presence of all the salts are rather small. The greatest shift (by 6 nm) of the DTCE absorption maximum to shorter wavelengths was observed for the mercury(II) perchlorate only. In order to select the DTCE concentration for further research the spectral dependence of the optical density vs. DTCE concentration was obtained (10 M was the most appropriate value of the DTCE concentration). Based on these results the DTCE extinction coefficient in aqueous solutions was determined (ε = 9329 M–1cm–1). Assuming the formation of the DTCE-cation complexes as 1:1, the metal perchlorates with lack and excess of the cations in the aqueous solutions were chosen. The absorption spectra had minor differences at DTCE concentration of 10–4 M and metal perchlorates concentration of 10–5 M (lack of the metal cations). Maximum hypsochromic shift by 4 nm was observed in the presence of mercury(II) perchlorate. It appeared that the lack of concentration of the metal salt does not allow the formation of complexes between the crown ether ring and a cation. The absorption intensity in the presence of most of salts was slightly reduced up to 85–95 % from baseline. The absorption spectra showed significant shifts of the absorption maxima to shorter wavelengths by 29 nm only in the presence of mercury(II) perchlorate at high concentrations (10–3 M). This fact proves a DTCE selectivity for mercury(II) cation. Moreover, the value of the shift depends on the salt concentration. An additional confirmation of these results was obtained in the study of the absorption spectra of the DTCE monolayers transferred from bidistilled water and aqueous solutions of Hg(ClO4)2 at constant surface pressure (about 10 mN/m). In all cases, the broad absorption maxima in the region of 350–450 nm were found. The main feature was that the maximum absorption for DTCE monolayer transferred to 10–5 M solution of Hg(ClO4)2 was 0.00575 a.u. at 406 nm. This is by 209% higher than those for the DTCE monolayer transferred from the water. Thus, the shift of the absorption maximum of DTCE monolayer in the presence of mercury salt was 23 nm to shorter wavelengths. This is further evidence of complex formation between DTCE (in monolayer) and mercury(II) cations from the aqueous subphase. For visualization and confirmation of the possibility of complex formation between DTCE and mercury(II) cation the quantum-chemical calculations of their structural models were carried out. The total energy of the optimized structure of the complex between DTCE cation and mercury(II) (with 2 perchlorate counter-anions) is set to E0 = –565.1231 a.u. It can be compared with the energies of individual species: the DTCE cation (E0 = –250.5477 a.u.) and Hg(ClO4)2 (E0 = –314.4877 a.u.). Thus, the change in energy (ΔE) upon complex formation is about –0.0877 a.u. (–230 kJ/mol). High energy of complex formation and high covalency of the Hg–S bonds explain the significant blue shift of the maximum in the absorption spectra of the solutions of DTCE with Hg(ClO4)2