Experimental results on mass-thickness distribution in spacecraft equipment

A technique is described for evaluating the shielding properties of spacecraft equipment with respect to cosmic radiation. A gamma-ray source is used in conjunction with a scintillation detector to determine mass-thickness distribution both in plane geometry for equipment units, and in spherical geometry for given points within the spacecraft. Equations are presented for calculating mass-thickness distribution functions, and the results are compared with experimental measurements

A gamma-ray testing technique for spacecraft

The simulated cosmic radiation effect on a spacecraft structure is evaluated by gamma ray testing in relation to structural thickness. A drawing of the test set-up is provided and measurement errors are discussed

Quantitative Biological Electron Probe Microanalysis with a Wavelength Dispersive Spectrometer

This paper describes the details of quantitative electron probe microanalysis (EPMA) performed with a wavelength dispersive spectrometer (WDS). EPMA was carried out on the giant neuron of a fresh frozen ganglion from the snail Lymnaea stagnalis. The freeze-dried cryosections were compared with sections of freeze-dried, embedded tissue. It was found, that in the ganglion there are two kinds of neurons with a different chlorine concentration of 11 mmole/liter and 32 mmole/liter. Isolated neurons in culture were shown to differ in elemental composition from those in the ganglion tissue

New sequence-based data on the relative DNA contents of chromosomes in the normal male and female human diploid genomes for radiation molecular cytogenetics

ABSTRACT: BACKGROUND: The objective of this work is to obtain the correct relative DNA contents of chromosomes in the normal male and female human diploid genomes for the use at FISH analysis of radiation-induced chromosome aberrations. RESULTS: The relative DNA contents of chromosomes in the male and female human diploid genomes have been calculated from the publicly available international Human Genome Project data. New sequence-based data on the relative DNA contents of human chromosomes were compared with the data recommended by the International Atomic Energy Agency in 2001. The differences in the values of the relative DNA contents of chromosomes obtained by using different approaches for 15 human chromosomes, mainly for large chromosomes, were below 2%. For the chromosomes 13, 17, 20 and 22 the differences were above 5%. CONCLUSION: New sequence-based data on the relative DNA contents of chromosomes in the normal male and female human diploid genomes were obtained. This approach, based on the genome sequence, can be recommended for the use in radiation molecular cytogenetics

The use of titanium alloys for details of downhole hammers

The influence of cementation technology of titanium alloy Ti-Al-Mn on its wear resistance is studied. It is established that after lubrication a friction pair with mineral oil the wear resistance of the cemented titanium alloy is comparable to wear resistance of the tempered steel 12HN3A, and in water medium surpasses it by 1.5 times. Decrease in the tendency to seizure with steel is the main reason for increase of wear resistance of titanium alloy. Industrial tests of the ASH43 hammer have shown that the use of titanium alloys for the manufacture of hammer strikers allows to increase impact capacity by 1.5 times and to increase drilling rate by 30 % compared to hammers with steel strikers

Right ventricular outflow tract reconstruction with decellularized human pulmonary valves in congenital heart diseases

Universitatea de Stat de Medicină și Farmacie “Nicolae Testemiţanu”, Spitalul Clinic Republican “Timofei Moşneaga”, Chișinău, Republica Moldova, Al XIII-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” și al III-lea Congres al Societății de Endoscopie, Chirurgie miniminvazivă și Ultrasonografie ”V.M.Guțu” din Republica MoldovaIntroducere: Matricea valvulară obţinută prin metodele ingineriei tisulare crează posibilitate de regenerare a ţesutului, un factor important în înlocuirea valvulară la copii. Scopul: Studierea eficacităţii detergenţilor în decelularizarea valvelor pulmonare umane şi a rezultatelor clinice la pacienţii care au suportat implantarea acestor valve. Material şi metode: Au fost prezervate 20 de homogrefe de la donatori cu timpul ischemiei calde cuprins între 2,5 şi 8,5 ore. Pentru decelularizare au fost utilizaţi doi detergenţi pentru 36 ore. În următoarele 96 ore homogrefele au suportat 8 cicluri de spălare în soluţie Ringer cu antibiotice şi antimicotice în condiţii de vibraţie continuă la temperatura de 37 0C. La un termen de 55,8±18,7 luni au fost investigaţi 32 pacienţi la care au fost implantate homogrefele valvulare pulmonare (HVP) decelularizate . Rezultate: În rezultatul preparării HVP cu utilizarea detergenţilor s-a obţinut înlăturarea totală a celulelor de pe matricea valvulară. Semne de degenerare, îngroşarea cuspelor, reducerea mobilităţii lor, dilatarea sau stenozarea valvulară n-a fost depistată în dinamică. Gradientul transvalvular mediu a rămas stabil (4.35±2.54 la 4.66±2.63 mmHg), iar diametrul end-diastolic al ventriculului drept nu s-a schimbat în comparaţiie cu suprafaţa corporală a pacienţilor. Concluzie: Prelucrarea HVP cu detergenţii SDS şi ND a demonstrat înlăturarea totală a celulelor donor de pe homogrefă, cu păstrarea optimală a integrităţii matricei şi membranei bazale. Corecţia chirurgicală a malformaţiilor cardiace congenitale utilizînd HVP decelularizate au arătat un rezultat bun la pacienţii pediatrici cu un potenţial de a se remodela în paralel cu creşterea fiziologică a copilului.Introduction: Non-immunogenic cell-free valvular scaffolds obtained by methods of tissue engineering have provided to induce in/vivo guided tissue regeneration and present a promising valve substitute especially for children. Aim: To investigate the efficacity of detergent treatment in decellularization of HPV tissue and clinical results in patients with implanted cell-free valvular grafts. Material and methods: Twenty PV allografts were harvested from nonbeating heart donors with warm ischemic time from 2,5 to 8,5 hours. Two detergents for 36 hours and eight washing cycles in Ringer solutions with antibiotics during 4 days were used to remove cellular remnants at 370C temperature under continuous shaking conditions. 32 patients with cell-free valvular grafts were investigated mean follow-up 55,8±18,7 months. Results: Treatment of PV with detergents resulted in complete loss of cusps, wall and myocardial cuff cellularity. No signs of pulmonary dilatation or stenosis, valve degeneration, cusps thickness, or reduction of cusp’s mobility were observed during follow-up. Mean transvalvular gradient remained stable (4.35±2.54 to 4.66±2.63 mmHg). End-diastolic diameter of the right ventricle remained unchanged in contrast to physiological increase to BSA of the patients Conclusions: Treatment of the HPVC with ND and SDS solution demonstrated the efficiency in a complete removal of the cells from the human valve tissue with optimal preservation of the scaffold fibres and basal membrane. Surgical correction of congenital heart diseases using “fresh” decellularized PV homografts provides good early postoperative results and has the potential to remodel in parallel with the somatic growth of the child