Photoelectrochemical Reactions at an Anthracene Cathode

Investigation of the peculiarities of the photoconductivity of an anthracene cathode in the redox system iodine-iodide has supplied information on the kinetics of photoelectrochemical reactions injecting holes into anthracene. The effect of the surface coverage of anthracene with adsorbed iodine, the dielectric constant of the solvent, and of the energy of exciting photons on the photoconductivity of an anthracene cathode has been studied. It is shown that at photon energies from 3.8 to 5.0 eV, greater than the forbidden zone width, the conduction band electrons participate in the iodine reduction reaction. In the spectral region of singlet absorption of anthracene, excitons participate in the electrochemical charge separation reaction. In the case of contact with a polar solvent, excitons break up at the surface levels formed by adsorbed iodine. In the case of contact with a weakly-polar solvent, excitation is transferred to adsorbed iodine. In the spectral region of weak optical absorption of anthracene, iodine particles excited directly by the light that had passed through the crystal participate in the reaction

Методы получения наночастиц и их размерно-чувствительные физические параметры

The varieties of the methods of nanoparicles synthesis are discussed in this review. Wet and dry chemistry processes, pulse sonoelectrochemistry, methods with use of supercritical CO2, and far from equilibrium systems of two liquids are considered and compared.Possible role of dissipative phenomena during the processes of new nanoparticles creation is under special attention.Настоящий обзор посвящен методам получения наночастиц. Рассмотрены методы «мокрой» и «сухой» химии, соноэлектрохимический метод, получение наночастиц с использованием сверхкритического диоксида углерода, границы двух жидкостей и др. Обсуждается возможное влияние диссипативных процессов в среде, где рождаются наночастицы, на их физические параметры

Observation of narrow baryon resonance decaying into pKs0pK^0_s in pA-interactions at 70GeV/c70 GeV/c with SVD-2 setup

SVD-2 experiment data have been analyzed to search for an exotic baryon state, the $\Theta^+$-baryon, in a $pK^0_s$ decay mode at $70 GeV/c$ on IHEP accelerator. The reaction $pA \to pK^0_s+X$ with a limited multiplicity was used in the analysis. The $pK^0_s$ invariant mass spectrum shows a resonant structure with $M=1526\pm3(stat.)\pm 3(syst.) MeV/c^2$ and $\Gamma < 24 MeV/c^2$. The statistical significance of this peak was estimated to be of $5.6 \sigma$. The mass and width of the resonance is compatible with the recently reported $\Theta^+$- baryon with positive strangeness which was predicted as an exotic pentaquark ($uudd\bar{s}$) baryon state. The total cross section for $\Theta^+$ production in pN-interactions for $X_F\ge 0$ was estimated to be $(30\div120) \mu b$ and no essential deviation from A-dependence for inelastic events $(\sim A^{0.7})$ was found.Comment: 8 pages, 7 figures, To be submitted to Yadernaya Fizika. v3-v5 - Some references added, minor typos correcte

Разработка метода получения pd - содержащих частиц для последующего синтеза электрокатализаторов

Platinum metals and their compounds are now widely used as catalysts for water electrolysis and fuel cells. We propose a new approach to the synthesis of nanoparticles. As model experiment we realized synthesis of palladium diacetate nanoparticles of controlled size. As special condition for new phase grow was chosen far from equilibrium boundary between two liquids [2]. Under this condition gradient of chemical potential the water - tetrahydrofuran (THF) interface was a powerful regulating factor of the palladium diacetate (II) particle size.Описан метод получения наноматериалов в неравновесном переходном слое, возникающем при приведении в контакт двух различных по своей химической природе смешивающихся жидкостей. Метод апробирован для получения Pd-содержащих наночастиц контролируемого размера, которые будут в дальнейшем использованы для получения электрокатализаторов. Предложенный метод не предполагает применения поверхностно-активных добавок, модифицирующих поверхность, что является ключевым моментом в процессах синтеза катализаторов. Рассмотрено влияние различных факторов на размер частиц диацетата палладия(II), образующихся в переходном слое на границе раздела вода - тетрагидрофуран (ТГФ)

Cинтез наночастиц Y(OH)CO3 и Y2О3 при использовании жидких межфазных границ и дальнейшая модификация их поверхности палладием

The nano-composite materials with different morphology and structure, including yttrium basic carbonate or yttrium oxide and palladium metal are obtained. The optimal conditions for synthesis of stable nanoparticles of yttrium basic carbonate are defined. It is established that yttrium basic carbonate goes to the oxide at 900 °C. Samples of nanomaterials were characterized by transmission electron microscopy, infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy.Получены наноразмерные композиционные материалы различной морфологии и структуры, включа-ющие гидроксокарбонат либо оксид иттрия и металлический палладий. Определены оптимальные условия синтеза стабильных наночастиц гидроксокарбоната иттрия, которые при температуре 900°С переходят в соответствующий оксид. Образцы наноматериалов охарактеризованы методами электронной просвечивающей микроскопии, ИК спектроскопии, рентгенофазового анализа, рентгеновской фотоэлектронной спектроскопии

Система двух смешивающихся жидкостей как генератор наночастиц. Синтез наночастиц BаSO4 при контакте растворов прекурсоров в воде и тетрагидрофуране

The system of two miscible liquids is presented as a generator of nanoparticles. This approach was tested experimentally with the synthesis of barium sulfate nanoparticles under non-equilibrium conditions after contact of perfectly miscible solutions as an example.The experimental results were compared with the dynamic model of transition layer. According to this model the smallest size of obtained particles is determined by the size of associates in the nucleation stage formed inside the rotating Bernard cells. The hypothesis of BaSO4 creation is based on the idea that the interface between a Bernard cell and the surrounding solution has barrier properties. The permeability of this barrier depends on the viscosity of the solution. The influence of the solvent polarity on the structure and size of nanoparticles was investigated. The dependence of the structure and size of the nanoparticles on the water/THF ratio was found. The influence of viscosity of the solution on the size of the nanoparticles was found and explained in terms of dynamic transition layer.Система двух смешивающихся жидкостей предложена в качестве генератора наночастиц. Действенность этого подхода проверена экспериментально на примере синтеза наночастиц сульфата бария при приведении в контакт растворов прекурсоров, содержащихся в разных фазах: фаза 1 - (H2O + TГФ) и фаза 2 - (H2O). Для объяснения полученных результатов привлечена развитая в настоящей работе динамическая модель переходного слоя, согласно которой наименьший размер получившихся частиц определяется размером ассоциатов предфазы, сформировавшихся во вращающихся ячейках Бенара. Высказано предположение, что граница раздела ячейки Бенара с окружающим раствором обладает определенными барьерными свойствами, которые зависят от вязкости. Получена зависимость размера нанокристаллических частиц от соотношения H2O/ТГФ

Cortactin Phosphorylated by ERK1/2 Localizes to Sites of Dynamic Actin Regulation and Is Required for Carcinoma Lamellipodia Persistence

Tumor cell motility and invasion is governed by dynamic regulation of the cortical actin cytoskeleton. The actin-binding protein cortactin is commonly upregulated in multiple cancer types and is associated with increased cell migration. Cortactin regulates actin nucleation through the actin related protein (Arp)2/3 complex and stabilizes the cortical actin cytoskeleton. Cortactin is regulated by multiple phosphorylation events, including phosphorylation of S405 and S418 by extracellular regulated kinases (ERK)1/2. ERK1/2 phosphorylation of cortactin has emerged as an important positive regulatory modification, enabling cortactin to bind and activate the Arp2/3 regulator neuronal Wiskott-Aldrich syndrome protein (N-WASp), promoting actin polymerization and enhancing tumor cell movement.In this report we have developed phosphorylation-specific antibodies against phosphorylated cortactin S405 and S418 to analyze the subcellular localization of this cortactin form in tumor cells and patient samples by microscopy. We evaluated the interplay between cortactin S405 and S418 phosphorylation with cortactin tyrosine phosphorylation in regulating cortactin conformational forms by Western blotting. Cortactin is simultaneously phosphorylated at S405/418 and Y421 in tumor cells, and through the use of point mutant constructs we determined that serine and tyrosine phosphorylation events lack any co-dependency. Expression of S405/418 phosphorylation-null constructs impaired carcinoma motility and adhesion, and also inhibited lamellipodia persistence monitored by live cell imaging.Cortactin phosphorylated at S405/418 is localized to sites of dynamic actin assembly in tumor cells. Concurrent phosphorylation of cortactin by ERK1/2 and tyrosine kinases enables cells with the ability to regulate actin dynamics through N-WASp and other effector proteins by synchronizing upstream regulatory pathways, confirming cortactin as an important integration point in actin-based signal transduction. Reduced lamellipodia persistence in cells with S405/418A expression identifies an essential motility-based process reliant on ERK1/2 signaling, providing additional understanding as to how this pathway impacts tumor cell migration

Cancer Biomarker Discovery: The Entropic Hallmark

Background: It is a commonly accepted belief that cancer cells modify their transcriptional state during the progression of the disease. We propose that the progression of cancer cells towards malignant phenotypes can be efficiently tracked using high-throughput technologies that follow the gradual changes observed in the gene expression profiles by employing Shannon's mathematical theory of communication. Methods based on Information Theory can then quantify the divergence of cancer cells' transcriptional profiles from those of normally appearing cells of the originating tissues. The relevance of the proposed methods can be evaluated using microarray datasets available in the public domain but the method is in principle applicable to other high-throughput methods. Methodology/Principal Findings: Using melanoma and prostate cancer datasets we illustrate how it is possible to employ Shannon Entropy and the Jensen-Shannon divergence to trace the transcriptional changes progression of the disease. We establish how the variations of these two measures correlate with established biomarkers of cancer progression. The Information Theory measures allow us to identify novel biomarkers for both progressive and relatively more sudden transcriptional changes leading to malignant phenotypes. At the same time, the methodology was able to validate a large number of genes and processes that seem to be implicated in the progression of melanoma and prostate cancer. Conclusions/Significance: We thus present a quantitative guiding rule, a new unifying hallmark of cancer: the cancer cell's transcriptome changes lead to measurable observed transitions of Normalized Shannon Entropy values (as measured by high-throughput technologies). At the same time, tumor cells increment their divergence from the normal tissue profile increasing their disorder via creation of states that we might not directly measure. This unifying hallmark allows, via the the Jensen-Shannon divergence, to identify the arrow of time of the processes from the gene expression profiles, and helps to map the phenotypical and molecular hallmarks of specific cancer subtypes. The deep mathematical basis of the approach allows us to suggest that this principle is, hopefully, of general applicability for other diseases

TMEM120A and B: Nuclear Envelope Transmembrane Proteins Important for Adipocyte Differentiation

<div><p>Recent work indicates that the nuclear envelope is a major signaling node for the cell that can influence tissue differentiation processes. Here we present two nuclear envelope trans-membrane proteins TMEM120A and TMEM120B that are paralogs encoded by the <i>Tmem120A</i> and <i>Tmem120B</i> genes. The TMEM120 proteins are expressed preferentially in fat and both are induced during 3T3-L1 adipocyte differentiation. Knockdown of one or the other protein altered expression of several genes required for adipocyte differentiation, <i>Gata3</i>, <i>Fasn</i>, <i>Glut4</i>, while knockdown of both together additionally affected <i>Pparg</i> and <i>Adipoq</i>. The double knockdown also increased the strength of effects, reducing for example <i>Glut4</i> levels by 95% compared to control 3T3-L1 cells upon pharmacologically induced differentiation. Accordingly, TMEM120A and B knockdown individually and together impacted on adipocyte differentiation/metabolism as measured by lipid accumulation through binding of Oil Red O and coherent anti-Stokes Raman scattering microscopy (CARS). The nuclear envelope is linked to several lipodystrophies through mutations in lamin A; however, lamin A is widely expressed. Thus it is possible that the TMEM120A and B fat-specific nuclear envelope transmembrane proteins may play a contributory role in the tissue-specific pathology of this disorder or in the wider problem of obesity.</p></div