Unified 1.9…4.0 MeV linear accelerators with interchangeable accelerating structures for customs inspection

A series of compact linear electron accelerators for 1.9, 2.5 and 4.0 MeV equipped with a local radiation shielding has been designed and constructed in the NPK LUTS, the D.V. Efremov Institute (NIIEFA). The accelerators are intended for mobile facilities used for customs inspection of large-scale containers. Results of optimizing calculations of irradiator parameters and electron dynamics, verified under accelerators’ testing, are presented in the report. The main design approaches allowing the construction of unified accelerators with interchangeable accelerating structures for energies in the range of 1.9…4.0 MeV are also given.У НПК ЛУЦ НІІЕФА розроблені і виготовлені кілька моделей компактних лінійних прискорювачів електронів на енергії 1.9, 2.5, і 4.0 МеВ, що призначені для митного огляду великогабаритних контейнерів. Особливістю розробки є уніфікація вузлів прискорювача, що дозволила при використанні взаємозамінних структур, що прискорюють, у тому самому конструктивному виконанні одержувати прискорені електрони з енергією у діапазоні 1.9…4.0 МеВ. Приведено результати оптимізації параметрів опромінення, що підтверджені при іспиті прискорювачів.В НПК ЛУЦ НИИЭФА разработаны и изготовлены несколько моделей компактных линейных ускорителей электронов на энергии 1.9, 2.5, и 4.0 МэВ, которые предназначены для таможенного досмотра крупногабаритных контейнеров. Особенностью разработки является унификация узлов ускорителя, что позволило при использовании взаимозаменяемых ускоряющих структур в одном и том же конструктивном исполнении получать ускоренные электроны с энергий в диапазоне 1.9…4.0 МэВ. Приведены результаты оптимизации параметров облучения, которые подтверждены при испытании ускорителя

New 15 MeV electron accelerator for non-destructive testing

A 15 MeV accelerator with the dose rate from 80 to 120 Gy/min at 1m from the target has been designed and manufactured in NPK LUTS, the D.V.Efremov Institute, NIIEFA. The accelerator is intended for nondestructive testing (radiography, introscopy, tomography) of large scale products. Under tests an X-ray beam with the boundary energy of 15-16 MeV and dose rate of 100 Gy/min has been produced. When operating with longer pulse lengths of the accelerated electron current, the beam power was up to 140 Gy/min; with lower currents the 18 MeV energy was attained at a dose rate of 40-50 Gy/min. Biperiodic accelerating structure with axial coupling cells is applied in the accelerator. The accelerating structure buncher provides RF-focusing of the electron beam, therefore there is no need for focusing the solenoid. The focus spot diameter is no more than 2mm. To provide the electron beam stability, the accelerator is equipped with a system for automatic frequency tuning (AFT). The AFT system ensures both coarse tuning of the driver frequency against the temperature of the accelerating structure and fine tuning - against the minimum reflected power. The anode voltage of the klystron amplifier is stabilized by using a de-Q-ing system. A charging choke and pulse forming network (PFN) are located inside the irradiator unit to increase the distance between the modulator and irradiator up to 100m and to reduce losses when high-voltage high-current pulses are transmitted. The low-voltage klystron (anode voltage up to 55 kV) applied in the accelerator allows reducing the machine weight and dimensions (1100 kg and 2040x880x920mm). The accelerator is equipped with a PC-based automatic control system. In the accelerator intended for the radiographic inspection there is an external collimator with movable diaphragm jaws for testing small fragments of an inspected product

Small-size 2.5 MeV electron accelerator with local radiation shielding

A novel design of a 2.5 MeV small-size linear electron accelerator with local radiation shielding is presented in the paper. The accelerator is intended for the use in mobile introscopic facilities. The main design approaches, weight / dimensions and results of factory tests are given

Myeloperoxidase-induced fibrinogen unfolding and clotting

Due to its unique properties and high biomedical relevance fibrinogen is a promising protein for the development of various matrixes and scaffolds for biotechnological applications. Fibrinogen molecules may form extensive clots either upon specific cleavage by thrombin or in thrombin-free environment, for example, in the presence of different salts. Here, we report the novel type of non-conventional fibrinogen clot formation, which is mediated by myeloperoxidase and takes place even at low fibrinogen concentrations (<0.1 mg/ml). We have revealed fibrillar nature of myeloperoxidase-mediated fibrinogen clots, which differ morphologically from fibrin clots. We have shown that fibrinogen clotting is mediated by direct interaction of myeloperoxidase molecules with the outer globular regions of fibrinogen molecules followed by fibrinogen unfolding from its natural trinodular to a fibrillar structure. We have demonstrated a major role of the Debye screening effect in regulating of myeloperoxidase-induced fibrinogen clotting, which is facilitated by small ionic strength. While fibrinogen in an aqueous solution with myeloperoxidase undergoes changes, the enzymatic activity of myeloperoxidase is not inhibited in excess of fibrinogen. The obtained results open new insights into fibrinogen clotting, give new possibilities for the development of fibrinogen-based functional biomaterials, and provide the novel concepts of protein unfolding. © 2022 Wiley Periodicals LLC

Neutrophil Activation by Mineral Microparticles Coated with Methylglyoxal-Glycated Albumin

Hyperglycemia-induced protein glycation and formation of advanced glycation end-products (AGEs) plays an important role in the pathogenesis of diabetic complications and pathological biomineralization. Receptors for AGEs (RAGEs) mediate the generation of reactive oxygen species (ROS) via activation of NADPH-oxidase. It is conceivable that binding of glycated proteins with biomineral particles composed mainly of calcium carbonate and/or phosphate enhances their neutrophil-activating capacity and hence their proinflammatory properties. Our research managed to confirm this hypothesis. Human serum albumin (HSA) was glycated with methylglyoxal (MG), and HSA-MG was adsorbed onto mineral microparticles composed of calcium carbonate nanocrystals (vaterite polymorph, CC) or hydroxyapatite nanowires (CP). As scopoletin fluorescence has shown, H2O2 generation by neutrophils stimulated with HSA-MG was inhibited with diphenyleneiodonium chloride, wortmannin, genistein and EDTA, indicating a key role for NADPH-oxidase, protein tyrosine kinase, phosphatidylinositol 3-kinase and divalent ions (presumably Ca2+) in HSA-MG-induced neutrophil respiratory burst. Superoxide anion generation assessed by lucigenin-enhanced chemiluminescence (Luc-CL) was significantly enhanced by free HSA-MG and by both CC-HSA-MG and CP-HSA-MG microparticles. Comparing the concentrations of CC-bound and free HSA-MG, one could see that adsorption enhanced the neutrophil-activating capacity of HSA-MG