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Orestas Ulčinas

Bio: Orestas Ulčinas is an academic researcher from Kaunas University of Technology. The author has contributed to research in topics: Laser & Axicon. The author has an hindex of 7, co-authored 28 publications receiving 102 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, high-order vector Bessel-Gauss beams from a theoretical perspective were applied to transparent-material laser micromachining, and two geometric-phase-based optical elements, a highorder $S$-wave plate and an axicon in combination with simple optical elements such as lenses, wave plates, and polarizers, were demonstrated.
Abstract: Here, we present thorough research into high-order vector Bessel-Gauss beams from a theoretical perspective, with experimental realization and application to transparent-material laser micromachining. Efficient, stable, high-quality, and power-vector Bessel-Gauss beam generation using two geometric-phase-based optical elements, a high-order $S$-wave plate and an axicon in combination with simple optical elements, such as lenses, wave plates, and polarizers, is demonstrated. Ultrashort pulse-vector Bessel-Gauss beams are used to induce modifications in the glass, creating three-dimensional tubular structures of type I and type II modification in D263T glass. Furthermore, samples containing tubular modifications are tested for etch selectivity in the femtosecond-laser-induced chemical-etching method with KOH solution by etching throughout channels.

16 citations

Journal ArticleDOI
TL;DR: In this paper, a high-quality vector Bessel beam was generated using an S-wave plate (radial/azimuth polarization converter) together with an ordinary glass axicon.
Abstract: In this work, we present efficient generation of a high-quality vector Bessel beam using an S-wave plate (radial/azimuth polarization converter) together with an ordinary glass axicon. We examine laser-induced modifications in glass with different pulse durations. We achieve material cracking and observe dominant crack propagation directions caused by the generated beam’s intensity asymmetry. By translating the beam, we demonstrate potential application of vector Bessel beams and their transverse polarization components for microprocessing of transparent materials using ultra-short pulses.

15 citations

Journal ArticleDOI
TL;DR: It is demonstrated that virgin PI films provide a suitable environment for the mobility, proliferation and intercellular communication of human bone marrow mesenchymal stem cells, and how cell behaviour varies on the micro‐machined PI films with holes of different diameters is discussed.
Abstract: Engineering of sophisticated synthetic 3D scaffolds that allow controlling behavior and location of the cells requires advanced micro/nano fabrication techniques. Ultrafast laser micro-machining employing a 1030 nm wavelength Yb:KGW femtosecond laser and a micro-fabrication workstation for micro-machining of commercially available 12.7 and 25.4 µm thickness polyimide (PI) film was applied. Mechanical properties of the fabricated scaffolds, i.e., arrays of differently spaced holes, were examined via custom-built uniaxial micro-tensile testing and finite element method simulations. We demonstrate that experimental micro-tensile testing results could be numerically simulated and explained by 2-material model, assuming that 2-6 µm width rings around the holes possessed up to 5 times higher Young's modulus and yield stress compared with the rest of the laser intacted PI film areas of “dog-bone” shaped specimens. That was attributed to material modification around the micro-machined holes in the vicinity of the position of the focused laser beam track during trepanning drilling. We demonstrate that virgin PI films provide a suitable environment for the mobility, proliferation, and intercellular communication of human bone marrow mesenchymal stem cells and discuss how cell behavior varies on the micro-machined PI films with holes of different diameters (3.1, 8.4, and 16.7 µm) and hole spacing (30, 35, 40, and 45 µm). We conclude that the holes of 3.1 µm diameter were sufficient for metabolic and genetic communication through membranous tunneling tubes between cells residing on the opposite sides of PI film but prevented the trans-migration of cells through the holes. This article is protected by copyright. All rights reserved.

14 citations

Journal ArticleDOI
TL;DR: In this article, a transient absorption spectroscopy focusing on localized surface plasmon resonance (LSPR) of photoexcited Cu nanoparticles was used to study ultrafast relaxation processes in diamond-like carbon (DLC) thin films with embedded CU nanoparticles, and the relaxation time was found to be independent of the excitation intensity up to tens of microjoule per square centimeter per pulse and to increase at higher intensities.
Abstract: Ultrafast relaxation processes in diamond-like carbon (DLC) thin films with embedded Cu nanoparticles (DLC:Cu nanocomposites) were investigated by means of transient absorption spectroscopy focusing on localized surface plasmon resonance (LSPR) of photoexcited Cu nanoparticles. Absorption spectra of the composite films correspond to the sum of absorption spectra of DLC matrix and Cu nanoparticles; however, Cu nanoparticles strongly dominate in the transient differential absorption. Excitations of DLC matrix and of Cu nanoparticles relax independently revealing no strong interaction. High sensitivity measurements enabled to obtain the hot electron relaxation dynamics in Cu nanoparticles in the low excitation intensity conditions. The relaxation time was found to be independent of the excitation intensity up to tens of microjoule per square centimeter per pulse and to increase at higher intensities. The relaxation time obtained at low excitation intensity was also found to increase by about 30 % in the samples with high Cu concentration, where larger nanoparticles were formed.

13 citations


Cited by
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Journal ArticleDOI
TL;DR: The combined data from numerous laboratories indicate that some TNT mediate a long-range gap junctional communication to coordinate metabolism and signaling, in relation to infectious, genetic, metabolic, cancer, and age-related diseases.
Abstract: Cell-to-cell communication is essential for the organization, coordination, and development of cellular networks and multi-cellular systems. Intercellular communication is mediated by soluble factors (including growth factors, neurotransmitters, and cytokines/chemokines), gap junctions, exosomes and recently described tunneling nanotubes (TNTs). It is unknown whether a combination of these communication mechanisms such as TNTs and gap junctions may be important, but further research is required. TNTs are long cytoplasmic bridges that enable long-range, directed communication between connected cells. The proposed functions of TNTs are diverse and not well understood but have been shown to include the cell-to-cell transfer of vesicles, organelles, electrical stimuli and small molecules. However, the exact role of TNTs and gap junctions for intercellular communication and their impact on disease is still uncertain and thus, the subject of much debate. The combined data from numerous laboratories indicate that some TNT mediate a long-range gap junctional communication to coordinate metabolism and signaling, in relation to infectious, genetic, metabolic, cancer, and age-related diseases. This review aims to describe the current knowledge, challenges and future perspectives to characterize and explore this new intercellular communication system and to design TNT-based therapeutic strategies.

161 citations

Journal ArticleDOI
TL;DR: Various PIs have the capacity to accommodate in vivo conditions in which they are able to function for a long time and can be judiciously certified as biocompatible.
Abstract: Polyimides (PIs) represent a benchmark for high-performance polymers on the basis of a remarkable collection of valuable traits and accessible production pathways and therefore have incited serious attention from the ever-demanding medical field. Their characteristics make them suitable for service in hostile environments and purification or sterilization by robust methods, as requested by most biomedical applications. Even if PIs are generally regarded as “biocompatible”, proper analysis and understanding of their biocompatibility and safe use in biological systems deeply needed. This mini-review is designed to encompass some of the most robust available research on the biocompatibility of various commercial or noncommercial PIs and to comprehend their potential in the biomedical area. Therefore, it considers (i) the newest concepts in the field, (ii) the chemical, (iii) physical, or (iv) manufacturing elements of PIs that could affect the subsequent biocompatibility, and, last but not least, (v) in vitro and in vivo biocompatibility assessment and (vi) reachable clinical trials involving defined polyimide structures. The main conclusion is that various PIs have the capacity to accommodate in vivo conditions in which they are able to function for a long time and can be judiciously certified as biocompatible.

89 citations

Journal Article
TL;DR: In this article, a femtosecond microfabrication of transparent dielectrics using non-fracting Bessel beams instead of the conventionally used Gaussian beams is presented.
Abstract: We demonstrate a novel approach to femtosecond microfabrication of transparent dielectrics, which employs nondiffracting Bessel beams instead of the conventionally used Gaussian beams. The main advantage of Bessel beams is the possibility of recording linear photomodified tracks, extending along the lines of nondiffractive beam propagation without sample translation, as would be required for Gaussian beams. Recording of patterns with an aspect ratio of up to 102–103 in vitreous silica using amplified femtosecond Ti:saphire laser pulses is demonstrated.

78 citations

Journal ArticleDOI
TL;DR: Several hot applications based on these magnificent beams such as optical trapping, material processing, free-space long-distance self-healing beams, optical coherence tomography, superresolution, sharp focusing, polarization transformation, increased depth of focus, birefringence detection based on astigmatic transformed BB and encryption in optical communication are discussed.
Abstract: Diffraction is a phenomenon related to the wave nature of light and arises when a propagating wave comes across an obstacle. Consequently, the wave can be transformed in amplitude or phase and diffraction occurs. Those parts of the wavefront avoiding an obstacle form a diffraction pattern after interfering with each other. In this review paper, we have discussed the topic of non-diffractive beams, explicitly Bessel beams. Such beams provide some resistance to diffraction and hence are hypothetically a phenomenal alternate to Gaussian beams in several circumstances. Several outstanding applications are coined to Bessel beams and have been employed in commercial applications. We have discussed several hot applications based on these magnificent beams such as optical trapping, material processing, free-space long-distance self-healing beams, optical coherence tomography, superresolution, sharp focusing, polarization transformation, increased depth of focus, birefringence detection based on astigmatic transformed BB and encryption in optical communication. According to our knowledge, each topic presented in this review is justifiably explained.

71 citations

Journal ArticleDOI
TL;DR: The current knowledge of TNT structure and formation as well as the role of TNTs in pathology, focusing on viral, prion, and malignant disease are summarized.
Abstract: Intercellular communication is essential for the development and maintenance of multicellular organisms. Tunneling nanotubes (TNTs) are a recently recognized means of long and short distance communication between a wide variety of cell types. TNTs are transient filamentous membrane protrusions that connect cytoplasm of neighboring or distant cells. Cytoskeleton fiber-mediated transport of various cargoes occurs through these tubules. These cargoes range from small ions to whole organelles. TNTs have been shown to contribute not only to embryonic development and maintenance of homeostasis, but also to the spread of infectious particles and resistance to therapies. These functions in the development and progression of cancer and infectious disease have sparked increasing scrutiny of TNTs, as their contribution to disease progression lends them a promising therapeutic target. Herein, we summarize the current knowledge of TNT structure and formation as well as the role of TNTs in pathology, focusing on viral, prion, and malignant disease. We then discuss the therapeutic possibilities of TNTs in light of their varied functions. Despite recent progress in the growing field of TNT research, more studies are needed to precisely understand the role of TNTs in pathological conditions and to develop novel therapeutic strategies.

60 citations