Formation of self-trapping waveguides in bulk PMMA media doped with Phenanthrenequinone

Experimental and theoretical investigations of light self-trapping waveguides in a bulk polymeric medium based on polymethylmethacrylate (PMMA) with photosensitive phenanthrenequinone (PQ)-molecules are examined. Self-channeling was generated for the first time in this nonlinear bulk PQ-PMMA media with a thickness up to several millimeters and 0.1 mol. % PQ-concentration. The experimental formation of volume waveguide structures with a length of 2 - 3 cm at different laser wavelengths (405 nm, 488 nm, and 514.5 nm) was demonstrated. The calculations based on a model for the laser beam propagation in the bulk PQ-PMMA medium with competitive nonlinearities are in a good agreement with the experiments

Cardiac multiscale bioimaging: from nano- through micro- to mesoscales.

Cardiac multiscale bioimaging is an emerging field that aims to provide a comprehensive understanding of the heart and its functions at various levels, from the molecular to the entire organ. It combines both physiologically and clinically relevant dimensions: from nano- and micrometer resolution imaging based on vibrational spectroscopy and high-resolution microscopy to assess molecular processes in cardiac cells and myocardial tissue, to mesoscale structural investigations to improve the understanding of cardiac (patho)physiology. Tailored super-resolution deep microscopy with advanced proteomic methods and hands-on experience are thus strategically combined to improve the quality of cardiovascular research and support future medical decision-making by gaining additional biomolecular information for translational and diagnostic applications

Spin-orbital Conversion of Bessel Light Beams By Liquid Crystal Elements

For the first time, the spin-orbital conversion of the linearly polarized Bessel beams in the process of their propagation in the electrically-controlled liquid crystal cell has been realized experimentally. Variations in the polarization, phase, and spatial structure of the beam have been analyzed. It has been shown that, when a Bessel beam is propagating along the liquid crystal director, the generated beam is orthogonally polarized, whereas the topological charge is varied by two unities. Keywords: Bessel light beams, spin-orbital conversion; liquid crystal

Sub-surface modifications in silicon with ultra-short pulsed lasers above 2 µm

Nonlinear optical phenomena in silicon such as self-focusing and multi-photon absorption are strongly dependent on the wavelength, energy, and duration of the exciting pulse, especially for wavelengths >2µm. We investigate the sub-surface modification of silicon using ultra-short pulsed lasers at wavelengths in the range of 1950–2400 nm, at a pulse duration between 2 and 10 ps and pulse energy varying from 1 µJ to 1 mJ. We perform numerical simulations and experiments using fiber-based lasers built in-house that operate in this wavelength range for the surface and sub-surface processing of Si-wafers. The results are compared to the literature data at 1550 nm. Due to a dip in the nonlinear absorption spectrum and a peak in the spectrum of the third-order nonlinearity, the wavelengths between 2000 and 2200 nm prove to be more favorable for creating sub-surface modifications in silicon. This is the case even though those wavelengths do not allow as tight focusing as those at 1550 nm. This is compensated for by an increased self-focusing due to the nonlinear Kerr-effect around 2100 nm at high light intensities, characteristic for ultra-short pulses

Photoaligned liquid-crystal lens with a single low-voltage electrode

The simple design of liquid-crystal lenses with single electrode and operation voltage below 5 V is highly desired. We offer a new type of photoaligned liquid-crystal lens, where the refractive gradient is created by voltage application due to the patterned twist angle gradient. In this paper, we present our calculations and experimental data

Controlled Diffraction Liquid-Crystal Structures with a Photoalignment Polymer

The characteristics of electric-field-controlled diffraction elements based on a nematic liquid crystal and a new photoalignment polymer have been studied. The photocross-linking of this polymer allows periodic oriented structures and liquid crystal phase gratings with a 30% diffraction efficiency in the first order to be formed

Efficient 1 W continuous-wave diode-pumped Er,Yb:YAl3(BO3)4 laser

We report the spectroscopy and high-power continuous-wave (CW) diode-pumped laser operation of Er:Yb:YAl3(BO3)4 crystal. Absorption and stimulated emission spectra, emission lifetimes, and efficiency of energy transfer from Yb3+ to Er3+ ions were determined. A CW Er:Yb:YAB laser emitting at 1602, 1555, and 1531 nm with output power as high as 1 W and slope efficiency up to 35% was demonstrated

Аналого-цифровое кодирование рельефно-фазовых голограмм с использованием анизотропных сред

The basis of the modern methods of protecting products, goods, documents, and equities are holographic security technologies, the development of which indicates that they are improving, new equipment and materials appear, new methods of hologram recording are being developed, their manufacturability is increasing, identification and authentication are being simplified. Combined images are widely used in modern holography. When creating combined images, various optical effects arise, such as moire, parallax, color change, etc., which, in combination with each other, as well as with other images (microtext, hidden images, sequential numbering, marking, coding, chemical indicators), permit to use them both to protect documents and to obtain an original artistic effect. This article discusses combined protective elements based on a relief-phase hologram with a deposited polymer carrier layer containing a latent image visible in polarized light. This protective element is named crystallogram. In the process of developing a crystallogram, the synthesis of monomers and the preparation of an anisotropic polarizable composition was mastered, a layer of polymerizable liquid crystals (PLC) was obtained with a contrast visualization of a latent image. A technology was developed for combining the relief-phase hologram with the deposited polymer carrier layer with the subsequent blocking of the polarizable liquid crystals (PLC) layer by protective varnish layers.Основой современных методов защиты продукции, товаров, документов и ценных бумаг являются голографические защитные технологии, развитие которых свидетельствует о том, что они совершенствуются, появляются новые оборудование и материалы, разрабатываются новые методы записи голограмм, повышается их технологичность, упрощается идентификация и проверка подлинности. В современной голографии комбинированные изображения применяются очень широко. При создании комбинированных изображений возникают различные оптические эффекты, такие как муар, параллакс, изменение цвета и другие, которые в комбинации между собой, а также с другими изображениями (микротекст, скрытые изображения, последовательная нумерация, маркировка, кодирование, химические индикаторы) позволяют использовать их как для защиты документов, так и для получения оригинального художественного эффекта. В статье рассматриваются комбинированные защитные элементы на основе рельефно-фазовой голограммы с нанесенным полимерным слоем-носителем, содержащим скрытое изображение, видимое в поляризованном свете. Данный защитный элемент получил название «кристаллограмма». В процессе разработки кристаллограммы был освоен синтез мономеров и приготовление анизотропной поляризуемой композиции, получен слой полимеризуемых жидких кристаллов (ПЖК) с контрастной визуализацией скрытого изображения. Отработана технология совмещения рельефно-фазовой голограммы с нанесенным полимерным слоем-носителем с последующим блокированием слоя ПЖК защитными лаковыми слоями

ПРИМЕНЕНИЕ МЕТОДА САМОРАСПРОСТРАНЯЮЩЕГОСЯ ВЫСОКОТЕМПЕРАТУРНОГО СИНТЕЗА ДЛЯ ПОЛУЧЕНИЯ ПОРИСТЫХ ВАКУУМНЫХ ВСТАВОК ПЛАНШАЙБ ОБОРУДОВАНИЯ ЭЛЕКТРОННОГО МАШИНОСТРОЕНИЯ

There are given the results of research the process of receiving by method of self-extending high-temperature synthesis of porous vacuum inserts of the faceplates used by production of semiconductor silicon plates at the enterprises of electronic mechanical engineering.Приведены результаты исследования процесса получения методом самораспространяющегося высокотемпературного синтеза пористых вакуумных вставок планшайб, используемых при производстве полупроводниковых кремниевых пластин на предприятиях электронного машиностроения

Probing the action of a novel anti-leukaemic drug therapy at the single cell level using modern vibrational spectroscopy techniques

Acute myeloid leukaemia (AML) is a life threatening cancer for which there is an urgent clinical need for novel therapeutic approaches. A redeployed drug combination of bezafibrate and medroxyprogesterone acetate (BaP) has shown anti-leukaemic activity in vitro and in vivo. Elucidation of the BaP mechanism of action is required in order to understand how to maximise the clinical benefit. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, Synchrotron radiation FTIR (S-FTIR) and Raman microspectroscopy are powerful complementary techniques which were employed to probe the biochemical composition of two AML cell lines in the presence and absence of BaP. Analysis was performed on single living cells along with dehydrated and fixed cells to provide a large and detailed data set. A consideration of the main spectral differences in conjunction with multivariate statistical analysis reveals a significant change to the cellular lipid composition with drug treatment; furthermore, this response is not caused by cell apoptosis. No change to the DNA of either cell line was observed suggesting this combination therapy primarily targets lipid biosynthesis or effects bioactive lipids that activate specific signalling pathways