Morphology and microstructure evolution of gold nanostructures in the limited volume porous matrices

The modern development of nanotechnology requires the discovery of simple approaches that ensure the controlled formation of functional nanostructures with a predetermined morphology. One of the simplest approaches is the self-assembly of nanostructures. The widespread implementation of self-assembly is limited by the complexity of controlled processes in a large volume where, due to the temperature, ion concentration, and other thermodynamics factors, local changes in diffusion-limited processes may occur, leading to unexpected nanostructure growth. The easiest ways to control the diffusion-limited processes are spatial limitation and localized growth of nanostructures in a porous matrix. In this paper, we propose to apply the method of controlled self-assembly of gold nanostructures in a limited pore volume of a silicon oxide matrix with submicron pore sizes. A detailed study of achieved gold nanostructures’ morphology, microstructure, and surface composition at different formation stages is carried out to understand the peculiarities of realized nanostructures. Based on the obtained results, a mechanism for the growth of gold nanostructures in a limited volume, which can be used for the controlled formation of nanostructures with a predetermined geometry and composition, has been proposed. The results observed in the present study can be useful for the design of plasmonic-active surfaces for surface-enhanced Raman spectroscopy-based detection of ultra-low concentration of different chemical or biological analytes, where the size of the localized gold nanostructures is comparable with the spot area of the focused laser beam. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.3.1.5.1Ministry of Education and Science of the Russian Federation, Minobrnauka: К-2018-036, N 211Russian Foundation for Fundamental Investigations, RFFI: 19-32-50058European Commission, ECMinistry of Science and Technology, MOSTFunding: This research was funded by H2020-MSCA-RISE2017-778308-SPINMULTIFILM Project, the scientific– technical program, ‘Technology-SG’ [project number 3.1.5.1], Ministry of Education and Science of the Russian Federation in the framework of Increase Competitiveness Program of NUST «MISiS» [№ К-2018-036], implemented by a governmental decree dated 16th of March 2013, N 211 and Russian Foundation for Fundamental Investigations [project number 19-32-50058].Acknowledgments: D.V.Y. greatly acknowledges the World Federation of Scientists National Scholarship Program. E.Yu.K., D.V.Y., V.D.B., and V.S. greatly acknowledge the European Union program Mobility Scheme for Targeted People-to-People-Contacts (MOST) for supporting research visits

Properties of Neutral Charmed Mesons in Proton--Nucleus Interactions at 70 GeV

The results of treatment of data obtained in the SERP-E-184experiment "Investigation of mechanisms of the production of charmed particles in proton-nucleus interactions at 70 GeV and their decays" by irradiating the active target of the SVD-2 facility consisting of carbon, silicon, and lead plates, are presented. After separating a signal from the two-particle decay of neutral charmed mesons and estimating the cross section for charm production at a threshold energy {\sigma}(c\v{c})=7.1 \pm 2.4(stat.) \pm 1.4(syst.) \mub/nucleon, some properties of D mesons are investigated. These include the dependence of the cross section on the target mass number (its A dependence); the behavior of the differential cross sections d{\sigma}/dpt2 and d{\sigma}/dxF; and the dependence of the parameter {\alpha} on the kinematical variables xF, pt2, and plab. The experimental results in question are compared with predictions obtained on the basis of the FRITIOF7.02 code.Comment: 9 pages, 9 figures,3 table

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

ОСОБЕННОСТИ ФОРМИРОВАНИЯ МЕДНОГО ОСАДКА В ПОРАХ ДИОКСИДА КРЕМНИЯ

Using the SiO2 porous templates on silicon substrate, Si/SiO2(Cu) nanostructures have been synthesized by electrochemical method. A comprehensive study by means of scanning electron, transmission electron, atomic force microscopy and diffraction analysis techniques have been conducted. The morphological features and the lateral dimensions of metal nanostructures, deposited in the pores, have been defined. A tendency to form copper agglomerates with dendritic shape have been shown. This structures are promising for using as catalyst or substrates for SERS.С использованием SiO2-пористых шаблонов на кремниевой подложке электрохимическим методом синтезированы наноструктуры Si/SiO2(Cu). Проведено их всестороннее изучение посредством электронной сканирующей, электронной просвечивающей, атомно-силовой микроскопии и дифракционных методов анализа. Определены морфологические особенности и латеральные размеры металлического осадка в порах. Показана тенденция к образованию агломератов меди дендритной формы, что указывает на перспективность использования таких структур при катализе и в спектроскопии гигантского комбинационного рассеяния света

НАПРЯЖЕННОСТЬ ЭЛЕКТРИЧЕСКОГО ПОЛЯ В БАРЬЕРНОМ СЛОЕ ПОРИСТОГО ОКСИДА АЛЮМИНИЯ ПРИ АНОДИРОВАНИИ

The electric field strength calculations inside porous alumina barrier layer during electrochemical anodizing in aqueous solutions of oxalic acid at a forming voltage of 90 to 250 V have been performed. The configuration of porous alumina cells with a porosity from 1 to 10 % have been used as the input data for calculations. It is found that the value of electric field strength inside porous alumina reaches 1010-1011 V/m. New phenomena and effects, appeared during alumina anodizing process with high forming voltages, have been analyzed.Представлены результаты расчета электрического поля в пористом оксиде алюминия при электрохимическом анодировании в электролитах на основе водных растворов щавелевой кислоты при напряжениях от 90 до 250 В. Для расчета использовались конфигурации ячеек пористых оксидов алюминия с пористостью от 1 до 10 %. Рассмотрены новые явления и эффекты, возникающие в процессе пористого анодирования алюминия при высоких напряжениях, когда напряженность электрического поля внутри пористого оксида алюминия достигает величин 1010-1011 В/м

ЗАВИСИМОСТЬ СИГНАЛА ГИГАНТСКОГО КОМБИНАЦИОННОГО РАССЕЯНИЯ СВЕТА ОТ ФОРМЫ СЕРЕБРЯНЫХ НАНОСТРУКТУР, ВЫРАЩЕННЫХ В ПОРАХ SiO2 /n-Si-ШАБЛОНА

Surface-enhanced Raman scattering is a powerful method used in chemoand biosensorics. The aim of this work was to determine the relationship between the signal of Surface-enhanced Raman scattering and the shape of silver nanostructures under the influence of laser radiation with different power.Plasmonic nanostructures were synthesized in silicon dioxide pores on monocrystalline silicon n-type substrate. The pores were formed using ion-track technology and selective chemical etching. Silver deposition was carried out by galvanic displacement method. Synthesis time was chosen as a parameter that allows controlling the shape of a silver deposit in the pores of silicon dioxide on the surface of single-crystal n-silicon during electrodeless deposition. Deposition time directly effects on the shape of metal nanostructures.Analysis of the dynamics of changing the morphology of the metal deposit showed that as the deposition time increases, the metal evolves from individual metallic crystallites within the pores at a short deposition time to dendritic-like nanostructures at a long time. The dependence of the intensity of Surface-enhanced Raman scattering spectra on the shape of the silver deposit is studied at the powers of a green laser (λ = 532 nm) from 2.5 μW to 150 μW on the model dye analyte Rodamin 6G. The optimum shape of the silver deposit and laser power is analyzed from this point of view design of active surfaces for Surface-enhanced Raman scattering with nondestructive control of small concentrations of substances.The silver nanostructures obtained in porous template SiO2 on n-type silicon substrate could be used as plasmon-active surfaces for nondestructive investigations of substances with low concentrations at low laser powers. Гигантское комбинационное рассеяние, усиленное поверхностью, является мощным методом, применяемым в хемо- и биосенсорике. Целью данной работы являлось определение взаимосвязи сигнала гигантского комбинационного рассеяния света с формой серебряных наноструктур при воздействии лазерного излучения с различной мощностью.Плазмонные наноструктуры синтезировались в порах диоксида кремния на подложке монокристаллического кремния n-типа, в котором поры формировались с использованием ионно-трековой технологии и селективного химического травления. Синтез серебра проводился методом безэлектродного осаждения. В качестве параметра, позволяющего управлять формой серебряного осадка в порах диоксида кремния на поверхности монокристаллического n-кремния при безэлектродном осаждении, выбрано время синтеза, которое непосредственно влияет на степень разрастания металлических наноструктур. Анализ динамики изменения морфологии металлического осадка показал, что при увеличении времени осаждения металл эволюционирует от отдельных металлических кристаллитов внутри пор при малых временах осаждения до дендритоподобных наноструктур при больших временах. Изучена зависимость интенсивности спектров гигантского комбинационного рассеяния света от формы серебряного осадка при мощностях зеленого лазера (λ = 532 нм) от 2,5 до 150 мкВт на модельном аналите Родамин 6Ж. Проведен анализ оптимальной формы серебряного осадка и мощности лазера с точки зрения последующего конструирования активных поверхностей для гигантского комбинационного рассеяния света при неразрушающем контроле малых концентраций веществ.Полученные серебряные наноструктуры в порах шаблона SiO2 на кремниевой подложке n-типа могут использоваться в качестве плазмонно-активных поверхностей при неразрушающем исследовании низких концентраций веществ на малых мощностях лазера.

Sexual dimorphism in cancer.

The incidence of many types of cancer arising in organs with non-reproductive functions is significantly higher in male populations than in female populations, with associated differences in survival. Occupational and/or behavioural factors are well-known underlying determinants. However, cellular and molecular differences between the two sexes are also likely to be important. In this Opinion article, we focus on the complex interplay that sex hormones and sex chromosomes can have in intrinsic control of cancer-initiating cell populations, the tumour microenvironment and systemic determinants of cancer development, such as the immune system and metabolism. A better appreciation of these differences between the two sexes could be of substantial value for cancer prevention as well as treatment