Nonlinear Doppler - Free comb-spectroscopy in counter-propagating fields

The method of Doppler - free comb - spectroscopy for dipole transitions was proposed. The calculations for susceptibility spectrum for moving two-level atoms driving by strong counter propagating combs have been done. The used theoretical method based on the Fourier expansion of the components of density matrix on two rows on kv (v-velocity of group of atoms, k-projection of wave vector) and {\Omega} (frequency between comb components). For testing of validity of this method the direct numerical integration was done. The narrow peaks with homogeneous width arise on the background of Doppler counter. The contrast of these peaks is large for largest amplitudes of comb-components. Power broadening is increasing with increase of field amplitudes. The spectral range of absorption spectrum is determined by the spectral range of comb generator and all homogeneous lines arise simultaneously. The spectral resolution is determined by the width of homogeneously-broadening lines. The physical nature of narrow peaks is in the existence of multi-photon transitions between manifolds of quasi-energy levels arising for different groups of atoms moving with velocities that satisfy to the resonant conditions 2kv= (n+l){\Omega}, where n, l - are integers and {\Omega} - frequency difference between comb teeth

Hydrogen bonding and coordination in normal and supercritical water from X-ray inelastic scattering

A direct measure of hydrogen bonding in water under conditions ranging from the normal state to the supercritical regime is derived from the Compton scattering of inelastically-scattered X-rays. First, we show that a measure of the number of electrons $n_e$ involved in hydrogen bonding at varying thermodynamic conditions can be directly obtained from Compton profile differences. Then, we use first-principles simulations to provide a connection between $n_e$ and the number of hydrogen bonds $n_{HB}$. Our study shows that over the broad range studied the relationship between $n_e$ and $n_{HB}$ is linear, allowing for a direct experimental measure of bonding and coordination in water. In particular, the transition to supercritical state is characterized by a sharp increase in the number of water monomers, but also displays a significant number of residual dimers and trimers.Comment: 14 pages, 5 figures, 1 tabl

Percolation transition of hydration water at hydrophilic surfaces

An analysis of water clustering is used to study the quasi-2D percolation transition of water adsorbed at planar hydrophilic surfaces. Above the critical temperature of the layering transition (quasi-2D liquid-vapor phase transition of adsorbed molecules) a percolation transition occurs at some threshold surface coverage, which increases with increasing temperature. The location of the percolation line is consistent with the existence of a percolation transition at the critical point. The percolation threshold at a planar surface is weakly sensitive to the size of the system when its lateral dimension increases from 80 to 150 A. The size distribution of the largest water cluster shows a specific two-peaks structure in a wide range of surface coverage : the lower- and higher-size peaks represent contributions from non-spanning and spanning clusters, respectively. The ratio of the average sizes of spanning and non-spanning largest clusters is about 1.8 for all studied planes. The two-peak structure becomes more pronounced with decreasing size of the planar surface and strongly enhances at spherical surfaces.Comment: 17 pages, 11 figure

Морфофункциональная характеристика отека-набухания коры головного мозга белых крыс после тяжелой черепно-мозговой травмы без и на фоне применения L-лизина эсцината

Aim of study The study is devoted to a morphometric assessment of the manifestations of edema-swelling of the somatosensory cortex (SSC) of the brain of white rats after severe traumatic brain injury (TBI) without using L-lysine escinate and when using it as a therapeutic effect.Material and methods We stained sections with hematoxylin-eosin and performed morphometric methods. On thin (4 μm) serial frontal sections of SSC, neurons and microvessels in the control (intact animals, n=5) were examined in 1 (n= 5), 3 (n=5), 5 (n=5), 7 (n=5) and 14 (n=5) days after injury without treatment (n=25, comparison group) and with treatment (n=25, main group). In color raster images (lens x100), using the plug-in filter “Find Maxima”, maximum brightness areas (MBA) were determined , which were then analyzed using the “Analyze Particles” program from ImageJ 1.52 s. MBA corresponded to SSC sites with a high degree of hydration of nerve tissue - edema-swelling. Statistical hypotheses were tested using nonparametric criteria.Results and discussion In control animals, a low degree of hydration of SSC tissue was noted (relative area 3-8%). In the comparison group, 1 and 3 days after STBI, foci of edema-swelling covered up to 30% of SSC, in 5 days - up to 15%, in 7 days - up to 20%, in 15 - up to 18%. Significant heteromorphism and heterogeneity of changes in the neuropil around neurons and blood vessels was noted. In the dynamics of the post-traumatic period, the proportion of large foci of edema-swelling (intra- and perineuronal, perivascular) decreased. In the main group, one day after STBI, there was a statistically significantly smaller number of foci of edema-swelling and their total relative area. The values range of these variables significantly decreased. L-lysine escinat affected the water balance most effectively in the acute post-traumatic period (day 1 and 3). The drug “smoothed out” the manifestation peaks (number, focal area) of edema-swelling: the values of the studied morphometric indicators were statistically significantly different. Consequently, morphometric signs of hydropic dystrophy after STBI were detected in both studied groups during the 15 days of observation.Conclusion The degree of SSC nervous tissue hydration increased after STBI. L-lysine escinate statistically significantly reduced manifestations of hydropic dystrophy. The drug significantly affected the degree of hydration of neural tissue observed in the early post-traumatic period.Цель Исследование посвящено морфометрической оценке проявлений отека-набухания соматосенсорной коры (ССК) головного мозга белых крыс после тяжелой черепно-мозговой травмы (ТЧМТ) на фоне использования в качестве лечебного воздействия L-лизина эсцината.Методы исследования Использована окраска срезов гематоксилином-иозином и методы морфометрии. На тонких (4 мкм) серийных фронтальных срезах ССК изучены нейроны и микрососуды в контроле (интактные животные, n=5), через 1 (n=5), 3 (n=5), 5 (n=5), 7 (n=5) и 14 (n=5) суток после травмы без лечения (n=25, группа сравнения) и с лечением (n=25, основная группа). На цветных растровых изображениях (объектив х100) с помощью плагин-фильтра “Find Maxima” определяли зоны максимальной яркости, которые затем анализировали с помощью “Analyze Particles” из программы ImageJ 1.52s. Зоны соответствовали участкам ССК с высокой степенью гидратации нервной ткани - отек-набухание. Статистические гипотезы проверяли с помощью непараметрических критериев.Результаты и обсуждение У контрольных животных отмечена низкая степень гидратации нервной ткани ССК (относительная площадь 3−8%). В группе сравнения через 1 и 3 суток после ТЧМТ очаги отека-набухания охватывали до 30% ССК, через 5 суток - до 15%, через 7 суток - до 20%, через 15 - до 18%. Отмечалась значительная гетероморфность и гетерогенность изменений в нейропиле, вокруг нейронов и сосудов. В динамике посттравматического периода доля крупных очагов отека-набухания (интра- и перинейрональных, периваскулярных) снижалась. В основной группе через одни сутки после ТЧМТ было статистически значимо меньшее количество очагов отека-набухания и их общая относительная площадь была меньше, чем в группе сравнения. Значительно уменьшался разброс значений данных переменных. Наиболее эффективно L-лизина эсцинат действовал на водный баланс в остром посттравматическом периоде (1-е и 3-и сутки). Препарат «сглаживал»  пики проявлений (количество, площадь очагов) отека-набухания: значения изученных морфометрических показателей статистически значимо отличались. Следовательно, морфометрическиепризнаки гидропической дистрофии после ТЧМТ выявлялись в обеих изученных группах на протяжении 15 суток наблюдения.Заключение После ТЧМТ увеличивалась степень гидратации нервной ткани ССК. L-лизин эсцинат статистически значимо уменьшал проявления гидропической дистрофии. Особенно выраженное влияние препарата на степень гидратации нервной ткани отмечено в раннем посттравматическом периоде

Морфофункциональная характеристика гиппокампа белых крыс в остром периоде после тяжелой черепно-мозговой травмы на фоне применения L-лизина эсцината

Aim of study. The study is devoted to the effect of L-lysine aescinat on the nervous tissue of the CA1 and CA3 fields of the hippocampus of the brain of white rats in the acute period after severe traumatic brain injury (TBI).Material and methods. TBI was simulated by applying a blow to the parieto-occipital region with a freely falling weight weighing 200-250 grams from a height of 50 cm using a special rail rack. The objectives of the study were: 1) comparative morphometric assessment of the degree of hydration, cyto- and glioarchitectonics of different layers of CA1 and CA3 fields after ischemia without treatment; 2) the effect of L-lysine aescinat on these indicators. We used histological (staining of sections with hematoxylin-eosin and Nissl), immunohistochemical (for NSE, MAP-2 and GFAP) and morphometric methods. On thin (4 μm) serial frontal sections of the hippocampus, neurons, astrocytes, microvessels and neuropiles were studied in control (intact animals, n=5) and 1 and 3 days after injury without treatment (n=10, comparison group) and with treatment ( n = 10, main group). The number density of neurons was determined using the Nissl staining of cells and by the reaction to NSE. The cytoskeleton of neurons was studied by detecting MAP-2, and astroglia by GFAP. On color raster images (staining with hematoxylin and eosin, x100) using the Find Maxima plug-in filter, the zones of maximum brightness were determined, which were then analyzed using Analyze Particles from the ImageJ 1.52s program. Zones of maximum brightness corresponded to areas of the hippocampus with a high degree of hydration of the nervous tissue - edema-swelling. The nature of the distribution, statistical hypotheses, and plotting were checked using Statistica 8.0 software and R environment.Results. In control animals, normochromic neurons without signs of changes in the cytoskeleton prevailed in all layers of fields CA1 and CA3, and a low degree of hydration of the nervous tissue was noted (the relative proportion of zones of maximum brightness was 5–8%). One and 3 days after TBI, there was a statistically significant increase in the focal content of dystrophic and necrobiotically altered neurons (95% confidence interval: 52–78%), manifestations of reactive gliosis were noted, and the proportion of zones of maximum brightness increased to 16%. Statistically significant layer-by-layer differences were revealed between the CA1 and CA3 fields of the hippocampus. The use of L-lysine aescinat had a statistically significant effect on the morphometric parameters of the nervous tissue of the hippocampus.Conclusion. In the early post-traumatic period after TBI, the degree of hydration of the nervous tissue of the hippocampus increased. Heteromorphicity of dystrophic and necrobiotic changes in different layers of CA1 and CA3 fields was noted. L-lysine aescinate had a statistically significant positive effect on these changes. To a greater extent, this is typical for the CA3 field. The revealed changes are considered not only as patho-, but also as sanogenetic structural mechanisms of protection and reorganization of the hippocampus in the acute post-traumatic period.1. In the acute period (1−3 days) after severe traumatic brain injury, the degree of hydration of all components of the hippocampal nervous tissue increased. In the group without treatment, 3 days after injury, the relative volume of edema-swelling zones varied from 10 to 13% in CA1 (control 3-7%) and from 8 to 16% in CA3 (control 5–10%).2. The heteromorphism of hydropic changes in the molecular layer, the layer of pyramidal neurons and the polymorphic layer was established. The maximum increase in the volume of free water (more than twofold) was characteristic of the molecular and polymorphic layer CA1, as well as the polymorphic layer CA3.3. The use of L-lysine aescinat in the acute period significantly changed the manifestations of hydropic dystrophy. One day after injury, the volume of free water increased in comparison with animals without treatment, and then, after 3 days, decreased, but remained higher than in the comparison group. The maximum effect of the drug was noted in field CA3.Цель исследования. Исследование посвящено изучению влияния L-лизина эсцината на нервную ткань полей СА1 и СА3 гиппокампа головного мозга белых крыс (Wistar) в остром периоде после тяжелой черепно- мозговой травмы (ТЧМТ).Материал и методы. ТЧМТ моделировали нанесением на теменно-затылочную область удара свободно падающим грузом массой 200−250 г с высоты 50 см с помощью специальной рельсовой стойки. Задачами исследования были: 1) сравнительная морфометрическая оценка степени гидратации, цито- и глиоархитектоники различных слоев полей СА1 и СА3 после ТЧМТ без лечения; 2) влияние на эти показатели L-лизина эсцината. Использованы гистологические (окраска срезов гематоксилином- эозином и по Нисслю), иммуногистохимические (на NSE, MAP-2 и GFAP) и морфометрические методы. На тонких (4 мкм) серийных фронтальных срезах гиппокампа изучены нейроны, астроциты, микрососуды и нейропиль в контроле (интактные животные, n=5) и через 1 и 3 суток после травмы без лечения (n=10, группа сравнения) и с лечением (n=10, основная группа). Численную плотность нейронов определяли с помощью окраски клеток по Нисслю и реакции на NSE. Цитоскелет нейронов изучали с помощью реакции на МАР-2, а астроглии — GFAP. На цветных растровых изображениях (окраска гематоксилином и эозином, объектив х100) с помощью плагин-фильтра “Find Maxima” определяли зоны максимальной яркости (ЗМЯ), которые затем анализировали с помощью “Analyze Particles” из программы ImageJ 1.52s. ЗМЯ соответствовали участкам гиппокампа с высокой степенью гидратации нервной ткани — отек-набухание. Характер распределения, статистические гипотезы, построение графиков проверяли с помощью программ Statistica 8.0 и среды R.Результаты. У контрольных животных во всех слоях полей СА1 и СА3 превалировали нормохромные нейроны без признаков изменения цитоскелета, отмечена низкая степень гидратации нервной ткани (относительная доля ЗМЯ 5−8%). Через 1 и 3 суток после ТЧМТ статистически значимо увеличивалось очаговое содержание дистрофически и некробиотически измененных нейронов (95% доверительный интервал: 52−78%), отмечались проявления реактивного глиоза, а доля ЗМЯ увеличивалась до 16%. Выявлены статистически значимые послойные различия между полями СА1 и СА3 гиппокампа. Применение L-лизина эсцината оказывало статистически значимое влияние на морфометрические показатели нервной ткани гиппокампа.Заключение. В раннем периоде после ТЧМТ увеличивалась степень гидратации нервной ткани гиппокампа. Отмечена гетероморфность дистрофических и некробиотических изменений в разных слоях полей СА1 и СА3. L-лизин эсцинат статистически значимо влиял на эти изменения. В большей степени это характерно для поля СА3. Выявленные изменения рассматриваются не только как пато-, но и как саногенетические структурные механизмы защиты и реорганизации гиппокампа в посттравматическом периоде.Выводы.1. В остром периоде (1−3 суток) после тяжелой черепно-мозговой травмы увеличивалась степень гидратации всех компонентов нервной ткани гиппокампа. В группе без лечения через 3 суток после травмы относительный объем зон отека-набухания варьировался от 10 до 13% в СА1 (контроль 3−7%) и от 8 до 16% — в СА3 (контроль 5−10%).2. Установлена гетероморфность гидропических изменений в молекулярном слое, слое пирамидных нейронов и полиморфном слое. Максимальное увеличение объема свободной воды (более чем в 2 раза) было характерно для молекулярного и полиморфного слоя СА1, а также полиморфного слоя СА3.3. Применение в остром периоде L-лизина эсцината способствовало статистически значимому изменению проявлений гидропической дистрофии. Через 1 сутки после травмы объем свободной воды увеличивался в сравнении с животными без лечения, а затем, спустя 3 суток, уменьшался, но оставался выше, чем в группе сравнения. Максимальное влияние препарата отмечено в поле СА3

Chronopotentiometric Evaluation of Ionization Degree and Dissociation Constant of Imidazolium-Based Ionic Liquid [C6Meim][NTf2] in Polymeric Plasticized Membranes

Ionic liquids (ILs) have a wide variety of applications in modern electrochemistry due to their unique electrolytic properties. In particular, they are promising candidates as dopants for polymeric membranes in potentiometric sensors and liquid-junction free reference electrodes. However, the effective use of ILs requires a comprehensive understanding of their electrolytic behavior in the polymeric phase. We report here the exploration of the electrolytic and diffusion properties of IL 1-hexyl-3-methyl-1H-imidazol-3-ium bis[(trifluoromethyl)sulfonyl]amide ([C6Meim][NTf2]) in a poly(vinyl chloride) matrix. Chronopotentiometry is utilized to determine the concentration of charge carriers, ionic diffusion coefficients and apparent dissociation constant of [C6Meim][NTf2] in PVC membranes plasticized with a mixture of [C6Meim][NTf2] and bis(2-ethylhexyl) sebacate (DOS) over a wide range of IL concentrations. The diffusion properties of [C6Meim][NTf2] are confirmed by NMR-diffusometry. The non-monotonic electrolytic behavior of the IL in PVC-DOS matrix is described for the first time. A maximum ionization degree and diffusion coefficient is observed at 30 wt.% of IL in the plasticizing mixture. Thus, it is shown that by varying the flexible parameter of the IL to plasticizer ratio in the polymeric phase one can tune the electrolytic and transport properties of sensing PVC membranes.This research was funded by the Russian Science Foundation, grant number 20-73-1003

The behavioral and immunological impact of maternal separation: a matter of timing

Maternal separation (MS), an early life stressful event, has been demonstrated to trigger neuropsychiatric disorders later in life, in particular depression. Experiments using rodents subjected to MS protocols have been very informative for the establishment of this association. However, the mechanism by which MS leads to neuropsychiatric disorders is far from being understood. This is probably associated with the multifactorial nature of depression but also with the fact that different research MS protocols have been used (that vary on temporal windows and time of exposure to MS). In the present study, MS was induced in rats in two developmental periods: for 6h per day for 14 days between postnatal days 2-15 (MS2-15) and 7-20 (MS7-20). These two periods were defined to differ essentially on the almost complete (MS2-15) or partial (MS7-20) overlap with the stress hypo-responsive period. Behavioral, immunological, and endocrine parameters, frequently associated with depressive-like behavior, were analyzed in adulthood. Irrespectively from the temporal window, both MS exposure periods led to increased sera corticosterone levels. However, only MS2-15 animals displayed depressive and anxious-like behaviors. Moreover, MS2-15 was also the only group presenting alterations in the immune system, displaying decreased percentage of CD8(+) T cells, increased spleen T cell CD4/CD8 ratio, and thymocytes with increased resistance to dexamethasone-induced cell death. A linear regression model performed to predict depressive-like behavior showed that both corticosterone levels and T cell CD4/CD8 ratio explained 37% of the variance observed in depressive-like behavior. Overall, these findings highlight the existence of "critical periods" for early life stressful events to exert programing effects on both central and peripheral systems, which are of relevance for distinct patterns of susceptibility to emotional disorders later in life.We acknowledge the Portuguese Foundation for Science and Technology (FCT) for providing a fellowship to S. Roque (SFRH/BPD/72710/2010). This work was also supported by FCT grants (co-financed by COMPETE funds) PTDC/SAU-NEU/105180/2008 and PTDC/PSI-PCO/116612/2010 and co-financed by the Portuguese North Regional Operational Program (ON.2 - O Novo Norte) under the National Strategic Reference Framework (QREN), through the European Regional Development Fund (FEDER)

Molecular dynamics simulation of humic substances

© 2014, Orsi. Humic substances (HS) are complex mixtures of natural organic material which are found almost everywhere in the environment, and particularly in soils, sediments, and natural water. HS play key roles in many processes of paramount importance, such as plant growth, carbon storage, and the fate of contaminants in the environment. While most of the research on HS has been traditionally carried out by conventional experimental approaches, over the past 20 years complementary investigations have emerged from the application of computer modeling and simulation techniques. This paper reviews the literature regarding computational studies of HS, with a specific focus on molecular dynamics simulations. Significant achievements, outstanding issues, and future prospects are summarized and discussed