Formation of Optical Low-dimensional Structures for Photonic Elements

In the present article, the formation of low-dimensional periodic structures with relief repeating the trajectory of movement of an AFM probe were presented. The parameters affecting their geometric dimensions: height, width, uniformity in the layer, etc., were investigated. The method of induced deposition of silver and/or gold clusters on the surface of a Bragg mirror in the presence of an external electric field was developed. The possibility of using such structures in optical elements, photoelectronic converters, optoelectronic devices of fiber optics, as well as the construction of photonic crystals (elements) based on the periodic structures is discussed.     Keywords: nanostructures, the atomic force microscope (AFM), the probe lithograph

Structure and Morphology Effects on the Optical Properties of Bimetallic Nanoparticle Films Laser Deposited on a Glass Substrate

Moving nanosecond laser system is used for laser-assisted thermodiffusion deposition of metallic nanoparticles from water-based colloidal solutions. The results obtained for both gold and silver nanoparticles show that film morphology strongly depends on laser scanning speed and the number of passages. We show, furthermore, the possibility of producing bimetallic Au:Ag thin films by laser irradiation of the mixed solutions. As a result of several laser scans, granular nanometric films are found to grow with a well-controlled composition, thickness, and morphology. By changing laser scanning parameters, film morphology can be varied from island structures to quasi-periodic arrays. The optical properties of the deposited structures are found to depend on the film composition, thickness, and mean separation between the particles. The transparency spectra of the deposited films are shown to be defined by their morphology

Hyperbaric Oxygen Therapy in Patients with COVID-19

The aim of the study is to evaluate the efficacy of hyperbaric oxygen therapy and its effect on oxidative stress and apoptosis in patients with new coronavirus infection COVID-19.Materials and methods. 90 patients diagnosed with new coronavirus infection caused by SARS-CoV-2 virus were examined. Hyperbaric oxygen therapy sessions were conducted in 57 patients (38 in severe condition (CT 3-4), 19 in moderate condition (CT 1-2)). The procedures were performed in 1.4-1.6 ATA mode for 40 minutes, 247 sessions in total were performed. The effect of hyperbaric oxygenation was assessed by measuring the level of oxygen saturation, the severity of oxidative stress and apoptosis of blood lymphocytes.Results. In all examined patients with new coronavirus infection caused by SARS-CoV-2, positive changes such as dyspnea reduction and improvement of general well-being were registered after hyperbaric oxygen therapy sessions. The level of oxygen saturation after the end of the hyperbaric oxygen therapy course was 95.0±1.6% (before the course — 91.3±5.9%), which allowed to return almost all patients to spontaneous respiration without the need for further oxygenation therapy. Hyperbaric oxygen therapy did not reduce the total antioxidant activity, however, it was associated with a decrease in the blood malone dialdehyde from 4.34±0.52 pmol/l to 3.98±0.48 pmol/l and a decrease in open circuit potential of platinum electrode from -22.78±24.58 mV to -37.69±17.4 mV. Besides, the positive effect of hyperbaric oxygen therapy was manifested in normalization of blood cell apoptosis.Conclusion. Hyperbaric oxygen therapy in patients with new coronavirus infection caused by the SARS-CoV-2 virus is an effective treatment method with multiple effects resulting in improvement of subjective indicators of the patients' condition, increase of hemoglobin oxygen saturation, decrease of lipid peroxidation intensity, activation of antioxidant system, restoration of pro- and antioxidant balance and apoptosis normalization

Безопасность применения гипербарической оксигенации при лечении COVID-19

Relevance. Acute respiratory infection COVID-19 caused by the SARS-CoV-2 (2019-nCov) coronavirus is severe and extremely severe in 15—20% of cases, which is accompanied by the need for respiratory support. Hyperbaric oxygenation is recognized as an effective therapy for replenishing any form of oxygen debt.Aim of study. To study the safety of HBO use in patients with COVID-19.Material and metods. We examined 32 patients with the diagnosis “Coronavirus infection caused by the virus SARS-CoV-2” (10 — moderately severe patients (CT 1–2), 22 — patients in serious condition (CT 3–4), who received course of hyperbaric oxygenation (HBO). The procedures were carried out in a Sechrist 2800 chamber (USA) at a mode of 1.4–1.6 AT for no more than 60 minutes. In total, the patients received 141 HBO sessions. Before and after each HBO session, the subjective indicators of the patient’s condition were assessed and the blood oxygen saturation was measured.Results. An algorithm for HBO course management was developed, which consists in using “soft” modes (up to 1.4 AT) during the first session, followed by pressure adjustment (not higher than 1.6 AT) during the course to achieve maximum therapeutic effect and comfort for the patient. Against the background of the HBO course, the patients showed an increase in blood oxygen saturation in patients in both surveyed groups, as well as positive dynamics in the form of a decrease in shortness of breath, an improvement in general well-being.Conclusion. The inclusion of daily sessions (at least 4) of hyperbaric oxygenation in “soft” modes (1.4–1.6 ATA) in the complex therapy for COVID-19 has shown its safety and preliminary positive effect on the subjective state of the examined patients and the dynamics of blood oxygen saturation.Актуальность. Острая респираторная инфекция COVID-19, вызываемая коронавирусом SARS-CoV-2 (2019-nCov), в 15–20% случаев протекает в тяжелой и крайне тяжелой степени, что сопровождается необходимостью респираторной поддержки. Гипербарическая оксигенация признана эффективным средством терапии, восполняющим любые формы кислородной задолженности.Цель работы. Исследование безопасности применения гипербарической оксигенации (ГБО) у пациентов с COVID-19.Материал и методы. Были обследованы 32 пациента с диагнозом «Коронавирусная инфекция, вызванная вирусом SARS-CoV-2» (10 — больные средней тяжести (КТ 1–2), 22 — больные в тяжелом состоянии (КТ 3–4)), которым был назначен курс гипербарической оксигенации (ГБО). Процедуры осуществляли в реанимационной барокамере Sechrist 2800 (CША) при режиме 1,4–1,6 АТА в течение не более 60 минут. Всего пациенты получили 141 сеанс ГБО. До и после каждого сеанса ГБО оценивали субъективные показатели состояния пациентов и измеряли насыщение крови кислородом.Результаты исследования. Был разработан алгоритм ведения курса ГБО, заключающийся в использовании при первом сеансе «мягких» режимов (до 1,4 АТА) с последующей корректировкой давления (не выше 1,6 АТА) в течение курса для достижения максимального терапевтического эффекта и комфорта для пациента. На фоне проведения курса ГБО у пациентов было отмечено повышение насыщения кислородом крови у пациентов в обеих обследованных группах, а также положительная динамика в виде уменьшения одышки улучшения общего самочувствия.Заключение. Включение в комплексную терапию при COVID-19 ежедневных сеансов (не менее 4) гипербарической оксигенации в «мягких» режимах (1,4–1,6 АТА) показало свою безопасность и предварительный положительный эффект на субъективное состояние обследованных пациентов и динамику насыщения крови кислородом

The Synthesis of Hybrid Gold-Silicon Nano Particles in a Liquid

Abstract We show that the laser ablation method can be efficiently employed for the synthesis of silicon nanoparticles (NP), which are characterized by a strong resonant optical response in the visible spectral range. A single layer composed of silicon NPs has been deposited from the colloidal solution generated by laser ablation. The formation of hybrid silicon-gold NPs as a result of the laser action on a mixed colloidal solution is observed. These hybrid NPs are characterized by broadening of the near-field photoluminescence spectra compared to pure silicon NPs. These results may be used for the realization of functional metasurfaces consisting of randomly distributed resonant NPs

Cavitation‐Free Continuous‐Wave Laser Ablation from a Solid Target to Synthesize Low‐Size‐Dispersed Gold Nanoparticles

International audienceContinuous wave (CW) radiation from a Yb-fiber laser (central wavelength 1064 nm, power 1–200 W) was used to initiate ablation of a gold target in deionized water and to synthesize bare (unprotected) gold nanoparticles. We show that the formed nanoparticles present a single low-size-dispersed population with a mean size of the order of 10 nm, which contrasts with previously reported data on dual populations of nanoparticles formed during pulsed laser ablation in liquids. The lack of a second population of nanoparticles is explained by the absence of cavitation-related mechanism of material ablation, which typically takes place under pulsed laser action on a solid target in liquid ambience, and this supposition is confirmed by plume visualization tests. We also observe a gradual growth of mean nanoparticle size from 8–10 nm to 20–25 nm under the increase of laser power for 532 nm pumping wavelength, whereas for 1064 nm pumping wavelength the mean size 8–10 nm is independent of radiation power. The growth of the nanoparticles observed for 532 nm wavelength is attributed to the enhanced target melting and splashing followed by additional heating due to an efficient excitation of plasmons over gold nanoparticles. Bare, low-size-dispersed gold nanoparticles are of importance for a variety of applications, including biomedicine, catalysis, and photovoltaics. The use of CW radiation for nanomaterial production promises to improve the cost efficiency of this technology

Laser ablative nanostructuring of Au in liquid ambience in continuous wave illumination regime

International audienceGold nanoparticles (Au NPs) attract particular attention because of their unique size-dependent chemical, physicochemical and optical properties and, hence, their potential applications in catalysis, nanoelectronics, photovoltaics and medicine. In particular, laser-produced colloidal nanoparticles are not only biocompatible, but also reveal unique chemical properties. Different laser systems can be used for synthesis of these colloids, varying from continuous wave (CW) to ultra-short femtosecond lasers. The choice of an optimum laser system is still a challenge in application development. To bring more light at this issue, we investigate an influence of laser parameters on nanoparticle formation from a gold target immersed in deionized water. First, an optical diagnostics of laser-induced hydrodynamic processes taking place near the gold surface is performed. Then, gold nanoparticle colloids with average particle sizes smaller than 10 nm and a very narrow dispersion are shown to be formed by CW laser ablation. The obtained results are compared with the ones obtained by using the second harmonics and with previous results obtained by using femtosecond laser systems. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Diagnostic Possibilities of Optical Coherent Tomography of the Retina during Compression in the Chiasm-Sellar Region

Recovery and preservation of visual functions during compression in the chiasm-sellar region is possible in the case of early diagnosis of pathology and timely surgical decompression. Today optical coherence tomography (OCT) of the retina is one of the most informative methods for diagnosing pathology of the retina and optic nerve. It can, due to the presence of early diagnostic criteria, promptly detect the compression in the chiasm-sellar region and expand the indications for surgical treatment. The literature review presents the results of optical coherent tomography (OCT) of the retina during compression in the chiasm-sellar region. An analysis of literature data revealed that in patients with chiasmatic compression, the thickness of the nerve fiber layer in the peripapillary and macular areas decreases, the thickness of the macular complex, consisting of the retinal ganglion cell layer and the inner plexiform layer, decreases. Also, there is a change in the value of asymmetry between the GCC thickness indices in the nasal and temporal halves of the macular region. It has been established that a decrease in the thickness index of a macular complex may precede changes in the visual field. According to the results of single studies, a correlation was found between the parameters of the peripapillary RNFL thickness and the the internal capillary retinal plexus density in the same areas. The results of literature sources’s analysis are summarized in the table by the parameters studied, the OCT model; etiology, treating methods and the results of the OCT study. Despite the results obtained, the early specific and sensitive OCT diagnostic criteria for chiasmatic compression have not yet been developed. In addition, a change in the thickness of GCC and RNFL can also be observed in the absence of chiasmatic compression in certain types of tumors and in the presence of comorbidities (arterial hypertension). In this regard, it is necessary to conduct further studies that will reveal the informative OСT-diagnostic criteria for compression in the chiasm-sellar region, develop diagnostic algorithms taking into account the type of tumor, the presence of concomitant pathology. Early diagnostic criteria for chiasmatic compression will expand the indications and improve the result of surgical treatment of patients