21 research outputs found
Chemical analysis of aerosol in the Venusian cloud layer by reaction gas chromatography on board the Vega landers
The experiment on sulfuric acid aerosol determination in the Venusian cloud layer on board the Vega landers is described. An average content of sulfuric acid of approximately 1 mg/cu m was found for the samples taken from the atmosphere at heights from 63 to 48 km and analyzed with the SIGMA-3 chromatograph. Sulfur dioxide (SO2) was revealed in the gaseous sample at the height of 48 km. From the experimental results and blank run measurements, a suggestion is made that the Venusian cloud layer aerosol consists of more complicated particles than the sulfuric acid water solution does
Ionization of Rydberg atoms by blackbody radiation
We have studied an ionization of alkali-metal Rydberg atoms by blackbody
radiation (BBR). The results of the theoretical calculations of ionization
rates of Li, Na, K, Rb and Cs Rydberg atoms are presented. Calculations have
been performed for nS, nP and nD states which are commonly used in a variety of
experiments, at principal quantum numbers n=8-65 and at the three ambient
temperatures of 77, 300 and 600 K. A peculiarity of our calculations is that we
take into account the contributions of BBR-induced redistribution of population
between Rydberg states prior to photoionization and field ionization by
extraction electric field pulses. The obtained results show that these
phenomena affect both the magnitude of measured ionization rates and shapes of
their dependences on n. A Cooper minimum for BBR-induced transitions between
bound Rydberg states of Li has been found. The calculated ionization rates are
compared with our earlier measurements of BBR-induced ionization rates of Na nS
and nD Rydberg states with n=8-20 at 300 K. A good agreement for all states
except nS with n>15 is observed. Useful analytical formulas for quick
estimation of BBR ionization rates of Rydberg atoms are presented. Application
of BBR-induced ionization signal to measurements of collisional ionization
rates is demonstrated.Comment: 36 pages, 16 figures. Paper is revised following NJP referees'
comments and suggestion
Collisional and thermal ionization of sodium Rydberg atoms I. Experiment for nS and nD atoms with n=8-20
Collisional and thermal ionization of sodium nS and nD Rydberg atoms with
n=8-20 has been studied. The experiments were performed using a two-step pulsed
laser excitation in an effusive atomic beam at atom density of about 2 10^{10}
cm^{-3}. Molecular and atomic ions from associative, Penning, and thermal
ionization processes were detected. It has been found that the atomic ions were
created mainly due to photoionization of Rydberg atoms by photons of blackbody
radiation at the ambient temperature of 300K. Blackbody ionization rates and
effective lifetimes of Rydberg states of interest were determined. The
molecular ions were found to be from associative ionization in Na(nL)+Na(3S)
collisions. Rate constants of associative ionization have been measured using
an original method based on relative measurements of Na_{2}^{+} and Na^{+} ion
signals.Comment: 23 pages, 10 figure
A new class of glycomimetic drugs to prevent free fatty acid-induced endothelial dysfunction
Background: Carbohydrates play a major role in cell signaling in many biological processes. We have developed a set of glycomimetic drugs that mimic the structure of carbohydrates and represent a novel source of therapeutics for endothelial dysfunction, a key initiating factor in cardiovascular complications. Purpose: Our objective was to determine the protective effects of small molecule glycomimetics against free fatty acidinduced endothelial dysfunction, focusing on nitric oxide (NO) and oxidative stress pathways. Methods: Four glycomimetics were synthesized by the stepwise transformation of 2,5dihydroxybenzoic acid to a range of 2,5substituted benzoic acid derivatives, incorporating the key sulfate groups to mimic the interactions of heparan sulfate. Endothelial function was assessed using acetylcholineinduced, endotheliumdependent relaxation in mouse thoracic aortic rings using wire myography. Human umbilical vein endothelial cell (HUVEC) behavior was evaluated in the presence or absence of the free fatty acid, palmitate, with or without glycomimetics (1µM). DAF2 and H2DCFDA assays were used to determine nitric oxide (NO) and reactive oxygen species (ROS) production, respectively. Lipid peroxidation colorimetric and antioxidant enzyme activity assays were also carried out. RTPCR and western blotting were utilized to measure Akt, eNOS, Nrf2, NQO1 and HO1 expression. Results: Ex vivo endotheliumdependent relaxation was significantly improved by the glycomimetics under palmitateinduced oxidative stress. In vitro studies showed that the glycomimetics protected HUVECs against the palmitateinduced oxidative stress and enhanced NO production. We demonstrate that the protective effects of preincubation with glycomimetics occurred via upregulation of Akt/eNOS signaling, activation of the Nrf2/ARE pathway, and suppression of ROSinduced lipid peroxidation. Conclusion: We have developed a novel set of small molecule glycomimetics that protect against free fatty acidinduced endothelial dysfunction and thus, represent a new category of therapeutic drugs to target endothelial damage, the first line of defense against cardiovascular disease
Complex plasma in glow discharge in a strong magnetic field
Experimental investigation of the rotation of dust structures in a DC discharge in a longitudinal strong magnetic field up to T has been performed for the first time. The main problem is the occurrence of discharge instability in moderate fields , which we have been able to solve. The dependence of rotation velocity on B is obtained. In fields the results are consistent with previous experiments, including rotation inversion. At (with the exception of the instability region), a much slower increase in the rotation velocity with increasing B is observed than at . In the region , there was a sharp slowing-down of the rotation, apparently due to the instability of the discharge, and a partial degradation of the dust structure occurred
Комбіноване лікування занедбаного раку щитоподібної залози
An analysis of the results of supervising 108 patients with primary unresectable locally invasive thyroid cancer, undergoing a course of treatment at the Donetsk Oncological Antitumoral Center (DOAC) from 2000 to 2011, served as a material for a research. The treatment in all the patients started by performing x-ray therapy by small fractions. A tumor regression was noted in all the patients of the group under study, consisting of 53 patients, enabling to perform a radical surgical interference, as a rule, in the range of extensive thyroidectomies with different types of lymph dissections. No essential changes were observed in 39 patients following the treatment performed (a stabilization process). Unfortunately, a disease progression was noted in 16 patients. Afterwards all the operated patients underwent radio iodine therapy. A five-year survival rate in patients undergoing a preoperative course of x-ray therapy, made up 63 %. All the patients who did not undergo an operation following a course of x-ray therapy died during a 2-year period. The introduction into clinical practice of a course of x-ray treatment in case of primary nonresectable thyroid cancer enables to perform surgical interference in a radical range, resulting in an improvement of the quality and duration of life, enabling to perform different variants of multimodality treatment of this particular cohort of patients afterwards.Материалом для исследования послужил анализ результатов наблюдения 108 больных с первично-нерезектабельным местнораспространенным раком щитовидной железы, которые проходили лечение в ДОПЦ с 2000 по 2011 год. У всех больных исследуемой группы лечение начинали с проведения ТГТ мелкими фракциями. В исследуемой группе у 53 пациентов отмечена регрессия опухоли, позволившая выполнить радикальное оперативное вмешательство, как правило, в объеме расширенных тиреоидэктомий с различными видами шейных лимфодиссекций. У 39 пациентов существенных изменений после проведенного лечения не наблюдалось (стабилизация процесса). К сожалению, у 16 больных отмечено прогрессирование болезни. Все прооперированные больные в последующем получали радиойодтерапию. Показатель пятилетней выживаемости у больных, получавших предоперационный курс ТГТ, составил 63 %. Все больные, которым не удалось выполнить операцию после курса ТГТ, умерли в течение двух лет. Внедрение в клиническую практику предоперационного курса ТГТ при первично-нерезектабельном раке щитовидной железы в большей части случаев дает возможность выполнения оперативного вмешательства в радикальном объеме, что приводит к улучшению качества и продолжительности жизни, позволяет проводить в дальнейшем различные варианты комплексного лечения данной категории больных.Матеріалом для дослідження послужив аналіз результатів спостереження 108 хворих на первинно-нерезектабельний місцевопоширений рак щитоподібної залози, які проходили лікування в ДОПЦ із 2000 по 2011 рік. У всіх осіб досліджуваної групи лікування починали з проведення ТГТ дрібними фракціями. У досліджуваній групі в 53 пацієнтів відзначена регресія пухлини, що дозволила виконати радикальне оперативне втручання, як правило, в обсязі розширеної тиреоїдектомії з різними видами шийних лімфодисекцій. У 39 пацієнтів істотних змін після проведеного лікування не спостерігалося (стабілізація процесу). На жаль, у 16 пацієнтів відзначено прогресування хвороби. Всі прооперовані особи в подальшому отримували радіойодтерапію. Показник п'ятирічної виживаності в осіб, які отримували передопераційний курс ТГТ, становив 63 %. Всі хворі, яким не вдалося виконати операцію після курсу ТГТ, померли протягом двох років. Впровадження в клінічну практику передопераційного курсу ТГТ при первинно-нерезектабельному раку щитоподібної залози в більшій частині випадків дає можливість виконання оперативного втручання в радикальному обсязі, що призводить до поліпшення якості і тривалості життя, дозволяє проводити в подальшому різні варіанти комплексного лікування хворих даної категорії