Biomedical subjects
Publications and source records attributed to A V Vinogradov.
Images with a spatial resolution of 120-150 nm were obtained with 46.9 nm light from a compact capillary-discharge laser by use of the combination of a Sc-Si multilayer-coated Schwarzschild condenser and a free-standing imaging zone plate. The results are relevant to the development of compact extreme-ultraviolet laser-based imaging tools for nanoscience and nanotechnology.
The damage threshold and damage mechanism of extreme-ultraviolet Sc/Si multilayer mirror coatings are investigated with focused nanosecond pulses at 46.9-nm radiation from a compact capillary-discharge laser. Damage threshold fluences of approximately 0.08 J/cm2 are measured for coatings deposited on both borosilicate glass and Si substrates. The use of scanning and transmission electron microscopy and small-angle x-ray diffraction techniques reveals the thermal nature of the damage mechanism. The results are relevant to the use of newly developed high-flux extreme-ultraviolet sources in applications.
The chemical reaction of a sample with atmospheric gases causes a significant error in the determinantion of the complex refractive index n = 1 - delta + ibeta in the extreme-ultraviolet region. The protection of samples removes this effect but hampers the interpretation of measurements. To overcome this difficulty, we derive the exact dependences on film thickness of the reflectivity and transmissivity of a protected film. These dependences greatly simplify the determination of delta and beta when the spectra of several films with different thickness and identical protection are measured. They also allow the verification of the delta(omega) obtained from the Kramers-Kronig relation and even make the Kramers-Kronig method unnecessary in many cases. As a practical application, the optical constants of Sc and Ti are determined at h omega = 18-70 eV and 18-99 eV, respectively. The essential feature of our experimental technique is deposition of a film sample directly on a silicon photodiode that allows easy operation with both thin (approximately 10-nm) and thick (approximately 100-nm) films. The comparison of calculated reflectivities of Si-Sc multilayers with the measured values shows the high accuracy of the determined delta(omega) and beta(omega).
A new non-destructive method based on x-ray microtomography (micro-CT) was developed to measure calcium density in bone. X-ray micro-CT was used as a quantitative approach to acquire and reconstruct virtual cross-sections through the sample. Accurate beam-hardening correction was implemented. Grey values in the virtual cross-sections were calibrated as calcium mineral density in bone. From these cross-sections, three-dimensional models were created. Calcium content was calculated directly from images and expressed as percentage per volume and per weight. Calcium mineral density was studied by this method in a unique set of bones isolated from newts (Pleurodeles waltlii Michah) that had travelled into space. A demineralization of 10% was shown as a consequence of sustained micro-gravity.
Presented herein is a case of successful surgical treatment of infrarenal aortic aneurysm in a 95-year-old patient with coexistent pathology. The patient underwent replacement of the abdominal aorta with implantation of the inferior mesenteric artery. After treatment of complications which occurred in the postoperative period, the patient was discharged home in a satisfactory condition. The success of surgical treatment of infrarenal aortic aneurysm in elderly patients depends on the anesthesiological control and postoperative care of patients.
A Sc-Si multilayer coating was applied to a replica of the 3600 groove/mm grating, developed for the SO82A spectroheliograph that flew on the Skylab mission, for the purpose of enhancing the normal-incidence efficiency in the extreme-ultraviolet region. The efficiency, measured at an angle of incidence of 6 degrees with synchrotron radiation, had a maximum value of 7.2% at a wavelength of 38 nm and was a factor of 3 higher than the efficiency of the gold-coated Skylab grating. The measured efficiency of the Sc-Si grating was in good agreement with the efficiency calculated by use of the modified integral method.
We have used a tabletop soft-x-ray laser and a wave-front division interferometer to probe the plasma of a pinch discharge. A very compact capillary discharge-pumped Ne-like Ar laser emitting at 46.9 nm was combined with a wave division interferometer based on Lloyd's mirror and Sc-Si multilayer-coated optics to map the electron density in the cathode region of the discharge. This demonstration of the use of tabletop soft-x-ray laser in plasma interferometry could lead to the widespread use of these lasers in the diagnostics of dense plasmas.
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131I-labelled bengali pink was used to perform radiohepatography in patients with circulatory failure. Both amplitude-time parameters of blood clearance curves and hepatograms and the generalized index of parameters of the linear 3-chambered reversible model of this tracer transport in the body indicate that the decrease of hepatic absorptive and excretory function in the presence of 131I-labelled bengali pink occurs in a direct relationship to the degree of circulatory insufficiency and developed in parallel with bilirubin metabolic disturbances. In some patients, hepatic lesion in the presence of Stages IIB-III circulatory insufficiency with signs of hepatocellular failure and cholestasis was accompanied only by moderate hepatic absorptive and excretory dysfunction against 131I-labelled bengali pink and by an increase in blood total bilirubin levels no more than that in Stage IIA circulatory insufficiency.
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Based on the results of examination of 58 patients with myocardial infarction, the authors propose a method for diagnosing posterior myocardial infarction by abdominal electrocardiographic mapping. The anterior abdominal wall shows the area from which one may record the direct markers of posterior myocardial infarction: abnormal Q wave, R wave regression, abnormal QS complex, as well as ST segment elevation which is typical of acute myocardial infarction. The anterior abdominal wall also defines the areas from which direct signs of inferior and lateral myocardial infarctions may be recorded.
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The possibility of myocardial necrosis occurrence in coronary failure proceeding as atypical myocardial infarction was examined in 176 patients with chronic types of coronary heart disease and in experiments with 16 dogs with reversible coronary failure simulated in chronic tests. 99mTe-labeled pyrophosphate myocardial scintigraphy was used in the clinical studies. Myocardial pyrophosphate accumulation was recorded in 37% of patients with angina pectoris without a history of myocardial infarction and 73% myocardial infarction survivals. Histological evidence for small myocardial necroses at various stages of their development was found in 12 dogs. Recurrent transient myocardial ischemias were shown to be able to lead to myocardial necroses that are not always followed by a typical course of acute myocardial infarction.
In 43 dead and 83 survived patients with myocardial infarction, the severity of the disease was compared with hourly changes in indications of a precordial cardiogram made in the first 2 days. The signs were defined, which made it possible to predict a relapse of myocardial infarction 10-15 hours before its onset. The rate of transformation of myocardial lesion foci to necrosis was found to affect the lifespan of patients. The end mass of myocardial infarction was shown to be formed via confluence of individual necrotic foci which appear in the myocardium at various intervals. The early signs were described, which enabled severe cases of myocardial infarction, resulting in death to be differentiated from those leading to a patient's recovery.
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A change in filterability of erythrocytes through a cellulose filter with pores 7 microns in diameter was examined in 67 patients with acute myocardial infarction. Dynamic evaluation of the filterability was compared with a process of necrotic focus development in time. The filterability was ascertained to have various phases coinciding with the development phases of a necrotic focus and to be an early prognostic indicator of myocardial infarction.