Photodissociation Dynamics of Molecular Fluorine in an Argon Matrix Induced by Ultrashort Laser Pulses

The electronic excitation induced by ultrashort laser pulses and the subsequent photodissociation dynamics of molecular fluorine in an argon matrix are studied. The interactions of photofragments and host atoms are modeled using a Diatomics-In-Molecule Hamiltonian. Two types of methods are compared: Quantum-classical simulations where the nuclei are treated classically, with surface-hopping algorithms to describe either radiative or non-radiative transitions between different electronic states. Fully quantum-mechanical simulations, but for a model system of reduced dimensionality, in which the two most essential degrees of freedom are considered. Some of the main results are: The sequential energy transfer events from the photoexcited F2 into the lattice modes are such that the ``reduced dimensionality'' model is valid for the first 200 fs. This, in turn, allows us to use the quantum results to investigate the details of the excitation process with short laser pulses. Thus, it also serves as a reference for the quantum-classical ``surface hopping'' model of the excitation process. Moreover, it supports the validity of a laser pulse control strategy developed on the basis of the ``reduced dimensionality'' model. Both in the quantum and quantum-classical simulations, the separation of the F atoms following photodissociation does not exceed 20 bohr. The cage exit mechanisms appear qualitatively similar in the two sets of simulations but quantum effects are quantitatively important. Nonlinear effects are important in determining the photoexcitation yield. In summary, this paper demonstrates that quantum-classical simulations combined with reduced dimensionality quantum calculations can be a powerful approach to the analysis and control of the dynamics of complex systems

On the Development of a New Nonequilibrium Chemistry Model for Mars Entry

This paper represents a summary of results to date of an on-going effort at NASA Ames Research Center to develop a physics-based non-equilibrium model for hypersonic entry into the Martian atmosphere. Our approach is to first compute potential energy surfaces based on accurate solutions of the electronic Schroedinger equation and then use quasiclassical trajectory calculations to obtain reaction cross sections and rate coefficients based on these potentials. We have presented new rate coefficients for N2 dissociation and CO dissociation and exchange reactions. These results illustrate shortcomings with some of the rate coefficients in Parks original T-Tv model for Mars entries and with some of the 30-45 year old shock tube data. We observe that the shock tube experiments of CO + O dissociation did not adequately account for the exchange reaction that leads to formation of C + O2. This reaction is actually the primary channel for CO removal in the shock layer at temperatures below 10,000 K, because the reaction enthalpy for exchange is considerably lower than the comparable value for dissociation

Interpolated wave functions for nonadiabatic simulations with the fixed-node quantum Monte Carlo method

Simulating nonadiabatic effects with many-body wave function approaches is an open field with many challenges. Recent interest has been driven by new algorithmic developments and improved theoretical understanding of properties unique to electron-ion wave functions. Fixed-node diffusion Monte Caro is one technique that has shown promising results for simulating electron-ion systems. In particular, we focus on the CH molecule for which previous results suggested a relatively significant contribution to the energy from nonadiabatic effects. We propose a new wave function ansatz for diatomic systems which involves interpolating the determinant coefficients calculated from configuration interaction methods. We find this to be an improvement beyond previous wave function forms that have been considered. The calculated nonadiabatic contribution to the energy in the CH molecule is reduced compared to our previous results, but still remains the largest among the molecules under consideration.Comment: 7 pages, 3 figure

Литолиз in vitro нефролитов ксидифоном и его смесями с калганом

A tormentil (Tormentilla erecta L.) composition for litholysis of urinary calculi of various types has been developed. The suggested composition allows to prevent precipitation of Ksidifon and to keep its high complexing ability.Изучено влияние растворов смесей калгана с ксидифоном на литолиз (растворение) мочевых камней различного состава. Предложены составы, позволяющие предотвратить осаждение ксидифона и сохранить его высокую комплексообразующую способность

ФИТОПРЕПАРАТЫ ДЛЯ ЛЕЧЕНИЯ И ПРОФИЛАКТИКИ УРАТНОГО НЕФРОЛИТИАЗА

The composition, structure and specific features of urate calculi are discussed in the article. It was shown that they consist of 95% of uric acid and its salts on an average by the X-ray phase and energy dispersive analysis of a number of samples extracted from the urinary tract of 24 urological patients. The mechanism of formation of urate stones is considered. It is noted that urate stones are formed at a urine under pH below 5.5. The factors reducing the development of urinary urolythiasis and uraturia are indicated. The drugs commonly used for the treatment and prevention of urate nephrolithiasis are listed. The role of phytotherapy is underlined in the treatment of urolithiasis in general and urate nephrolithiasis in particular. It is concluded that the composition of plant compositions should include natural compounds of the alkaloid class. The most promising compositions of medicinal plants were determined, and the effect of herbal extracts of various compositions on the pH of the solution and the loss of stone massВ статье обсуждаются состав, структура и специфические особенности уратных конкрементов. На основании исследования методами рентгенофазового и энергодисперсионного анализа ряда образцов, извлеченных из мочевых путей 24 урологических больных, показано, что они в среднем на 95% состоят из мочевой кислоты и ее солей. Рассмотрен механизм образования уратных камней. Перечислены препараты, обычно применяемые для лечения и профилактики уратного нефролитиаза. Подчеркнута роль фитотерапии в лечении мочекаменной болезни вообще и уратного нефролитиаза - в частности. Сделан вывод, что в состав растительных композиций должны входить природные соединения класса алкалоидов. Определены наиболее перспективные композиции лекарственных растений, и в системе in vitro прослежено воздействие травяных экстрактов различного состава на величину рН раствора и убыль массы камня. Установлено, что предложенные сборы, в состав которых входит тысячелистник, любисток, душица, толокнянка, корни подсолнечника, обеспечивают повышение рН мочи до 6.5-6.7 и поддержание его на этом уровне, а также убыль массы камня свыше 40-60%

Фитопрепараты для лечения и профилактики фосфатного нефролитиаза

The work presents the results of a research on the effect of water extracts of herbal preparations on phosphate concrements of different phase composition taken in vitro from 56 patients. Interrelation between the composition of the extracts and the pH of urine was found. Recommendations on the selection of herbal preparations providing favorable conditions for the litholysis of phosphate concrements were given.В работе представлены результаты исследования воздействия водных экстрактов травяных сборов на образцы фосфатных камней различного фазового состава, взятых у 56 пациентов, в системе in vitro. Выявлена связь между составом экстрактов и рН мочи. Выданы рекомендации по подбору фитопрепаратов, обеспечивающих благоприятные условия для литолиза фосфатных камней

Фитохимические основы создания препаратов для литолиза оксалатных конкрементов

The aim of this work was to search for and study new phytopreparations based on natural plant materials (medicinal plants) that are necessary for effective litholysis of oxalate stones in patients with urolithiasis. New phytomedications were proposed and studied in which litholytic action is due to the presence of certain combinations of flavonoids and some other types of biologically active substances. In a study carried out to obtain total extracts of natural flavonoids from several medicinal plants obtained and studied litholytic properties of new pharmaceutical compositions together with previously known herbal remedies. The effectiveness of the new phytopreparations demonstrated by native oxalate calculi different composition isolated from patients with urolithiasis after surgical management.В статье рассматриваются особенности применения фитопрепаратов для профилактики и лечения мочекаменной болезни, в частности, оксалатного нефролитиаза

Biochemical evidence for an alternate pathway in N-linked glycoprotein biosynthesis

Asparagine-linked glycosylation is a complex protein modification conserved among all three domains of life. Herein we report the in vitro analysis of N-linked glycosylation from the methanogenic archaeon Methanococcus voltae. Using a suite of synthetic and semisynthetic substrates, we show that AglK initiates N-linked glycosylation in M. voltae through the formation of α-linked dolichyl monophosphate N-acetylglucosamine, which contrasts with the polyprenyl diphosphate intermediates that feature in both eukaryotes and bacteria. Notably, AglK has high sequence homology to dolichyl phosphate β-glucosyltransferases, including Alg5 in eukaryotes, suggesting a common evolutionary origin. The combined action of the first two enzymes, AglK and AglC, afforded an α-linked dolichyl monophosphate glycan that serves as a competent substrate for the archaeal oligosaccharyl transferase AglB. These studies provide what is to our knowledge the first biochemical evidence revealing that, despite the apparent similarity of the overall pathways, there are actually two general strategies to achieve N-linked glycoproteins across the domains of life.National Institutes of Health (U.S.) (Grant GM039334

Effects of estrogens and bladder inflammation on mitogen-activated protein kinases in lumbosacral dorsal root ganglia from adult female rats

BACKGROUND: Interstitial cystitis is a chronic condition associated with bladder inflammation and, like a number of other chronic pain states, symptoms associated with interstitial cystitis are more common in females and fluctuate during the menstrual cycle. The aim of this study was to determine if estrogens could directly modulate signalling pathways within bladder sensory neurons, such as extracellular signal-related kinase (ERK) and p38 mitogen-activated protein (MAP) kinases. These signalling pathways have been implicated in neuronal plasticity underlying development of inflammatory somatic pain but have not been as extensively investigated in visceral nociceptors. We have focused on lumbosacral dorsal root ganglion (DRG) neurons projecting to pelvic viscera (L1, L2, L6, S1) of adult female Sprague-Dawley rats and performed both in vitro and in vivo manipulations to compare the effects of short- and long-term changes in estrogen levels on MAPK expression and activation. We have also investigated if prolonged estrogen deprivation influences the effects of lower urinary tract inflammation on MAPK signalling. RESULTS: In studies of isolated DRG neurons in short-term (overnight) culture, we found that estradiol and estrogen receptor (ER) agonists rapidly stimulated ER-dependent p38 phosphorylation relative to total p38. Examination of DRGs following chronic estrogen deprivation in vivo (ovariectomy) showed a parallel increase in total and phosphorylated p38 (relative to beta-tubulin). We also observed an increase in ERK1 phosphorylation (relative to total ERK1), but no change in ERK1 expression (relative to beta-tubulin). We observed no change in ERK2 expression or phosphorylation. Although ovariectomy increased the level of phosphorylated ERK1 (vs. total ERK1), cyclophosphamide-induced lower urinary tract inflammation did not cause a net increase of either ERK1 or ERK2, or their phosphorylation. Inflammation did, however, cause an increase in p38 protein levels, relative to beta-tubulin. Prior ovariectomy did not alter the response to inflammation. CONCLUSIONS: These results provide new insights into the complex effects of estrogens on bladder nociceptor signalling. The diversity of estrogen actions in these ganglia raises the possibility of developing new ways to modulate their function in pelvic hyperactivity or pain states

AglH, a thermophilic UDP‑<i>N</i>‑acetylglucosamine‑1‑phosphate:dolichyl phosphate GlcNAc‑1‑phosphotransferase initiating protein<i> N</i>‑glycosylation pathway in <i>Sulfolobus acidocaldarius</i>, is capable of complementing the eukaryal Alg7

AglH, a predicted UDP-GlcNAc-1-phosphate:dolichyl phosphate GlcNAc-1-phosphotransferase, is initiating the protein N-glycosylation pathway in the thermoacidophilic crenarchaeon Sulfolobus acidocaldarius. AglH successfully replaced the endogenous GlcNAc-1-phosphotransferase activity of Alg7 in a conditional lethal Saccharomyces cerevisiae strain, in which the first step of the eukaryal protein N-glycosylation process was repressed. This study is one of the few examples of cross-domain complementation demonstrating a conserved polyprenyl phosphate transferase reaction within the eukaryal and archaeal domain like it was demonstrated for Methanococcus voltae (Shams-Eldin et al. 2008). The topology prediction and the alignment of the AglH membrane protein with GlcNAc-1-phosphotransferases from the three domains of life show significant conservation of amino acids within the different proposed cytoplasmic loops. Alanine mutations of selected conserved amino acids in the putative cytoplasmic loops II (D(100)), IV (F(220)) and V (F(264)) demonstrated the importance of these amino acids for cross-domain AlgH activity in in vitro complementation assays in S. cerevisiae. Furthermore, antibiotic treatment interfering directly with the activity of dolichyl phosphate GlcNAc-1-phosphotransferases confirmed the essentiality of N-glycosylation for cell survival