Intramolecular photo-physical processes and spectral-luminescence properties of a dye merocyanine 540 and its complexes with water

Merocyanine 540 (M540) is famous dye that used in electronics and medicine. An important feature of the dye is a significant intramolecular transfer of the electron density in the excited state. Experimentally was investigated the electronic absorption and fluorescence spectra in different solvents M540. Electronic structure, spectra and rate constants of photo-physical processes of an isolated molecule and its complexes with water molecules were calculated by INDO method with spectroscopic parameterization. Analysis of the results allowed establishing the effect of individual fragments and hydrogen bonds with water on the electronic charge transfer between the terminal units in the state S1. Examination of photo-physical processes of decomposition of the fluorescent state was showed that the intramolecular processes of decay of the S1 state are not the cause of the differences calculated and experimental fluorescence quantum yield. Consideration of trans-cis photoisomerization leads to the elimination of this non-compliance. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Proton and carbon-ion minibeam therapy: from modeling to treatment

Arrays of minibeams of protons and $^{12}$C in tissue-like media were modeled with Geant4 toolkit. A set of beam energies was used in simulations to provide a Spead-out Bragg peak (SOBP) extended by 6 cm in depth for protons as well as for $^{12}$C. In both cases, beams of 0.3 mm or 0.5 mm FWHM were arranged at the entrance to a water phantom either on a rectangular or an hexagonal grid to compare two kinds of projectiles and different minibeam patterns. Differential and cumulative dose-volume histograms (DVH) were calculated and compared for protons and $^{12}$C as dose uniformity metrics. A uniform dose distribution was easily achieved with protons due to an enhanced lateral scattering of these projectiles in comparison to $^{12}$C. The cumulative DVHs calculated for 0.3 mm or 0.5 mm minibeams almost coincide in the target volume, but diverge for different grid patterns. In contrast, cumulative entry DVHs were found similar for both grid patterns, but different for 0.3 mm and 0.5 mm minibeams.Comment: 8 pages, 5 figures, talk given at the XXV International Baldin Seminar on High Energy Physics Problems "Relativistic Nuclear Physics and Quantum Chromodynamics", September 18-23, 2023, Dubna, Russi

Optical properties of new indotricarbocyanine dye as a limiter of laser radiation power

We present results of experimental and theoretical studies of the optical characteristics of a new indotricarbocyanine dye that is capable of effectively limiting the power of laser radiation in the visible spectral range. The spectral-luminescent and energy characteristics of the dye molecules and their absorption spectra from the excited state with nanosecond resolution are investigated experimentally. Quantum-chemical methods are used to calculate electronic absorption spectra from the ground (S0 → Sn) and excited (S1 → Sn) states and to determine the nature of electronic states of the molecule and the rate constants of intramolecular photo-physical processes. The results of the theoretical research agree with experimental data. It is shown that the investigated dye has singlet-singlet absorption at 400–600 nm. Nonlinear absorption of the dye upon excitation by radiation of the second harmonic of a Nd:YAG laser is studied by z-scanning with an open diaphragm. The ratio of dye absorption cross sections from the excited and ground states at 532 nm is determined in the framework of a three-level model. The results are compared with those for previously studied compounds

Influence of the focused ion beam parameters on the etching of planar nanosized multigraphene/SiC field emitters

The equipment of the Collective Usage Center “Nanotechnologies” and the Research and Educational Center "Nanotechnologies" of Southern Federal University was used for this study. This work was funded by Internal grant of Southern Federal University No. VnGr-07/2017-26

The fluorescence analysis of laser photolysis of phenols in water

Оцифровано в НБ ТГ

Creation of a magnetic driven gate for THz rays

In this paper, magnetic fluids based on iron oxide Fe3O4 and 5BDSR alloy were obtained. Magnetic particles were obtained by nanosecond pulsed laser ablation. The preparation of the magnetic fluid was carried out by mechanical and ultrasonic stirring in a solution of polymethylphenylsiloxane. It is shown that under the influence of an external magnetic field, the spectral properties of the magnetic fluid of the 5BDSR alloy correspond to characteristics that can be used to create a magnetic gate

Study of field emission nanostructures based on graphene films on SiC using scanning probe microscopy

В работе исследованы морфология и электрические характеристики автоэмиссионных графен/SiC наноструктур с использованием методов СЗМ. Проведена оценка влияния геометрии графен/SiC наноструктур с учетом радиуса закругления вершины эмиттера и межэлектродного расстояния на автоэлектронную эмиссию.The morphology and electrical characteristics of field emission graphene/SiC nanostructures were investigated using SPM. The effect of design of graphene/SiC nanostructures on field emission was estimated taking into account the rounding-off radius of the emitting top and the interelectrode distance.Результаты работы были получены с использованием инфраструктуры Центра коллективного пользования и научно-образовательного центра «Нанотехнологии» Южного федерального университета

Скрининг белков-биомаркеров рака легкого с помощью мультиплексной электрохимической сенсорной системы на основе аптамеров

The aim of this work is the development and demonstration of the method of simultaneous detection of several biomarkers of lung cancer in the blood plasma of patients using a multiplex electrochemical testing system based on DNA aptamers. DNA aptamers are a new class of synthetic affinity probes obtained by in vitro or in vivo selection procedure by the systematic evolution of ligands by exponential enrichment (SELEX).Materials and methods. A set of aptamers obtained previously by selection for postoperative lung cancer tissue was used to create a multiplex electrochemical biochip. Identification of aptamer target proteins was performed using a modified affinity enrichment method (AptaBID). Molecular targets for the used set of aptamers to lung cancer were defined as vimentin, defensin, a light chain of myosin, tubulin alpha 1-B, neutrophil elastase and A1 elongation factor 1.Measurements of the presence of these biomarker proteins in blood plasma were carried out using electrochemical detection. The difference between peak heights before and after plasma deposition on the electrodes modified by aptamers was considered as a response of the system to the presence of protein onco-markers in blood plasma. Blood plasma of healthy volunteers was used as control.Results. Research showed that in the blood plasma of all the patients with lung cancer the content of biomarker proteins that bind to aptamers on electrode surfaces was increased. The increased content of these proteins in the blood plasma of patients suggests the presence of invasiveness and metastasis of tumors and their chemo-resistance.Цель. Разработка и демонстрация метода одновременного определения нескольких биомаркеров рака легкого в плазме крови больных с помощью мультиплексной электрохимической сенсорной системы, основанной на ДНК-аптамерах. ДНК-аптамеры представляют собой новый класс синтетических аффинных реагентов, получаемых с помощью процедуры селекции in vitro или in vivo методом систематической эволюции лигандов экспоненциальным обогащением (SELEX).Материалы и методы. Для создания мультиплексного электрохимического биочипа использовалось несколько аптамеров, полученных ранее путем селекции к послеоперационным тканям рака легкого. Идентификацию белков-мишеней аптамеров проводили с помощью модифицированного метода аффинного обогащения (AptaBID). В качестве молекулярных мишеней для использованного набора аптамеров к раку легкого были определены виментин, дефензин, легкая цепь миозина, тубулин альфа 1-B, нейтрофил эластаза и фактор удлинения 1 A1. Определение наличия этих белков-биомаркеров в плазме крови проводили с помощью электрохимической детекции. В качестве отклика системы на присутствие белков-онкомаркеров в плазме крови выступала разница между величинами пиков на квадратно-волновой вольтамперограмме до и после нанесения плазмы на электроды с предварительно иммобилизированными на их поверхности аптамерами. Для контрольного сравнения использовалась плазма крови здоровых добровольцев.Результаты. Показано, что в плазме крови всех исследованных больных раком легкого повышено содержание белков-биомаркеров, связывающихся с аптамерами на поверхностях электродов. Повышенное содержание этих белков в плазме крови больных предполагает их химиорезистентность и высокую степень инвазивности и метастазирования опухолей