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Denis Emanuil Tranca

Denis Emanuil Tranca
National University of Science and Technology POLITEHNICA Bucharest

Doctor of Engineering

About

79
Publications
8,841
Reads
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555
Citations
Additional affiliations
March 2015 - present
Universitatea Națională de Știință și Tehnologie Politehnica București
Position
  • Laboratory Assistant
Education
September 2012 - September 2015
Universitatea Națională de Știință și Tehnologie Politehnica București
Field of study
  • High Resolution Optical Microscopy Technics
October 2010 - July 2012

Publications

Publications (79)
Article
Infectious diseases are acknowledged as one of the leading causes of death worldwide. Statistics show that the annual death toll caused by bacterial infections has reached 14 million, most of which are caused by drug-resistant strains. Bacterial antibiotic resistance is currently regarded as a compelling problem with dire consequences, which motiva...
Article
Full-text available
A wide palette of nanoscale imaging techniques operating in the near-field regime has been reported to date, enabling an important number of scientific breakthroughs. While the tuning and benchmarking of near-field microscopes represent a very important step for optimizing the outputs of the imaging sessions, no generally acknowledged standards exi...
Article
Full-text available
This study explores the mechanical and optical properties of nanoporous copper (NPC) films dealloyed in acid and base using qualitative and quantitative measurements. Two types of NPC films (NPC 1 and NPC 2) were prepared by dealloying precursor films in different corrosive solutions. The films were characterized using atomic force microscopy (AFM)...
Article
Full-text available
A thorough understanding of biological species and emerging nanomaterials requires, among other efforts, their in-depth characterization through optical techniques capable of nano-resolution. Nanoscopy techniques based on tip-enhanced optical effects have gained tremendous interest over the past years, given their potential to obtain optical inform...
Article
Full-text available
Chromium nitride thin films are known for their good mechanical properties. We present the characteristics of ultrathin chromium nitride films under 400 nm thickness deposited on silicon substrates by direct current and high-power impulse magnetron sputtering techniques. The methods of investigation of the CrN films were scanning electron microscop...
Article
Full-text available
Second harmonic generation microscopy (SHG) is generally acknowledged as a powerful tool for the label-free three-dimensional visualization of tissues and advanced materials, with one of its most popular applications being collagen imaging. Despite the great need, progress in super-resolved SHG imaging lags behind the developments reported over the...
Preprint
Full-text available
Investigation techniques based on tip-enhanced optical effects, capable to yield spatial resolutions down to nanometers level, have enabled a wide palette of important discoveries over the past twenty years. Recently, their underlying optical setups are beginning to emerge as useful tools to modify and manipulate matter with nanoscale spatial resol...
Preprint
Full-text available
Chromium Nitride thin films are known for their good mechanical properties. We present the characteristics of ultrathin Chromium Nitride films under 400 nm thickness deposited on silicon substrates by direct current and high-power impulse magnetron sputtering techniques. The methods of investigation of the CrN films were scanning electron microscop...
Preprint
Full-text available
A thorough understanding of biological species and of emerging nanomaterials requires, among others, their in-depth characterization with optical techniques capable of nano-resolution. Nanoscopy techniques based on tip-enhanced optical effects have gained over the past years tremendous interest given their potential to probe various optical propert...
Preprint
Full-text available
Second Harmonic Generation Microscopy (SHG) is generally acknowledged as a powerful tool for the label-free 3D visualization of tissues and advanced materials, with one of its most popular applications being collagen imaging. Although the great need, progress in super-resolved SHG imaging lags behind the developments reported over the past years in...
Article
Full-text available
Second harmonic generation (SHG) microscopy is acknowledged as an established imaging technique capable to provide information on the collagen architecture in tissues that is highly valuable for the diagnostics of various pathologies. The polarization-resolved extension of SHG (PSHG) microscopy, together with associated image processing methods, re...
Article
Full-text available
Scattering-type scanning near-field optical microscopy (s-SNOM) has emerged over the past years as a powerful characterization tool that can probe important properties of advanced materials and biological samples in a label-free manner, with spatial resolutions lying in the nanoscale realm. In this work, we explore such usefulness in relationship w...
Conference Paper
The local refractive index of polymethyl methacrylate is modified due to low power femtosecond laser exposure in the proximity of a sharp metallic tip. Such modified nanoscale-sized regions can be used for photonic crystals creation.
Article
Full-text available
Background In recent years, a variety of imaging techniques operating at nanoscale resolution have been reported. These techniques have the potential to enrich our understanding of bacterial species relevant to human health, such as antibiotic-resistant pathogens. However, owing to the novelty of these techniques, their use is still confined to add...
Article
Super‐resolution microscopy techniques can provide answers to still pending questions on prokaryotic organisms but are yet to be employed at their full potential for this purpose. To address this, we evaluate the ability of the rhodamine‐like KK114 dye to label various types of bacteria, to enable imaging of fine structural details with Stimulated...
Article
Placed at the junction of laser-scanning and probe-scanning techniques, scattering scanning near-field optical microscopy (s-SNOM) is a promising tool for the optical investigation of surfaces at nanoscale resolution. In this work we expand the current possibilities of representing s-SNOM data by coupling typical s-SNOM results (amplitude and phase...
Article
Scattering-type Scanning Near Field Optical Microscopy (s-SNOM) is currently regarded as a powerful tool for exploring important optical properties at nanoscale resolutions depending only on the size of a sharp tip that is scanned across the sample surface while being excited with a focused laser beam. Recently, it was shown that, among others, s-S...
Article
Full-text available
Despite intense research on high entropy films, the mechanism of film growth and the influence of key factors remain incompletely understood. In this study, high entropy films consisting of five elements (FeCoNiCrAl) with columnar and nanometer-scale grains were prepared by magnetron sputtering. The high entropy film growth mechanism, including the...
Article
Full-text available
Quantitative second harmonic generation microscopy was used to investigate collagen organization in the fibrillar capsules of human benign and malignant thyroid nodules. We demonstrate that the combination of texture analysis and second harmonic generation images of collagen can be used to differentiate between capsules surrounding the thyroid foll...
Conference Paper
We discuss an imaging approach that allows a better understanding of nanoscale datasets collected with Apertureless Scanning Near-Field Optical Microscopy, based on a multimodal system that incorporates multiple ASNOM and far-field Laser Scanning Microscopy variants.
Conference Paper
In our work we present some investigations on biological and biomedical samples acquired by using a new multimodal microscopy system which integrates more techniques based on far field and near field having hundred nanometers or few nanometers resolutions. The system allows simultaneous image acquisition by using multiple optical imaging modalities...
Article
Full-text available
Apertureless scanning near-field optical microscopy (ASNOM) has attracted considerable interest over the past years as a result of its valuable contrast mechanisms and capabilities for optical resolutions in the nanoscale range. However, at this moment the intersections between ASNOM and the realm of bioimaging are scarce, mainly due to data interp...
Article
We present a novel method for nanoscale reconstruction of complex refractive index by using scattering-type Scanning Near-field Optical Microscopy (s-SNOM). Our method relies on correlating s-SNOM experimental image data with computational data obtained through simulation of the classical oscillating point-dipole model. This results in assigning a...
Article
Full-text available
Although silicon carbide is a highly promising crystalline material for a wide range of electronic devices, extended and point defects which perturb the lattice periodicity hold deep implications with respect to device reliability. There is thus a great need for developing new methods that can detect silicon carbide defects which are detrimental to...
Article
Imaging tissue samples by polarization‐resolved second harmonic generation microscopy provides both qualitative and quantitative insights into collagen organization in a label‐free manner. Polarization‐resolved second harmonic generation microscopy goes beyond simple intensity‐based imaging by adding the laser beam polarization component and applyi...
Article
Scattering scanning near-field optical microscopy has become in the past decade a powerful tool for high-resolution optical investigations. However, a deeper understanding of the signal detection, demodulation and reconstruction techniques is still required. In this paper we use the mathematical concept that forms the base for modulation/demodulati...
Article
Nano-engineered polyelectrolyte capsules (NPCs) were investigated using a multimodal approach based on Confocal Laser Scanning Microscopy, scattering-type Scanning Near-Field Optical Microscopy and Atomic Force Microscopy. Our experiment demonstrates that correlating optical information collected with far-field and near-field techniques and topogra...
Conference Paper
In our work we present some investigations on biological samples at micro and nanoscale by using nonlinear effects in laser scanning microscopy techniques. We developed an integrated multimodal system that allows for the simultaneous image acquisition from multiple optical imaging modalities. Our system includes several microscopy techniques workin...
Article
Full-text available
Nonlinear Laser Scanning Microscopy (NLSM) techniques have been demonstrated in the past two decades as powerful imaging tools for disease diagnostics (DD). Currently, in most DD related experiments the interpretation of NLSM data sets is performed by trained specialists. Such approaches are both time consuming and prone to errors due to inter- and...
Article
Full-text available
Laser Scanning Microscopy Techniques such as Confocal Microscopy, Two Photon Excitation Microscopy, Second Harmonic Generation Microscopy or Fluorescence Lifetime Imaging have been successfully employed to date for imaging skin cancer. However, the resolution that such techniques can provide is limited by diffraction, which prevents accurately imag...
Article
Complementary laser scanning microscopy micrographs are considered as pairs consisting in a master image (MI) and a slave image (SI), the latter with potential for facilitating the interpretation of the MI. We propose a strategy based on reversible watermarking for embedding a lossy compressed version of the SI into the MI. The use of reversible wa...
Conference Paper
Ocular tissues are transparent and often hard to be imaged under natural conditions with clinical devices. Since pathologies, surgery and external damage modify their structure in an uncontrolled manner, an accurate visualization and analysis are of great importance. Some of these changes have their origin at submicron-scale and can not be detected...
Article
Full-text available
Complementary laser scanning microscopy micrographs are considered as pairs consisting in a master image (MI) and a slave image (SI), the latter with potential for facilitating the interpretation of the MI. We propose a strategy based on reversible watermarking for embedding a lossy compressed version of the SI into the MI. The use of reversible wa...
Article
Full-text available
Scattering scanning near-field optical microscopy (s-SNOM) has been demonstrated as a valuable tool for mapping the optical and optoelectronic properties of materials with nanoscale resolution. Here we report experimental evidence that trapped electric charges injected by an electron beam at the surface of dielectric samples affect the sample–dipol...
Article
Contrast enhancement (CE) plays an important role in digital photography, medical imaging or scientific visualization, compensating for deficient dynamic range aspects. Our experiments show that CE via histogram modification influences the detection of gradient based local invariant features (LIF) and the matching of their descriptors. We bring evi...
Conference Paper
Full-text available
This paper deals with the filtering of microscopic images with moire like noise patterns. The proposed method analyzes the magnitude spectrum of the Fast Fourier Transform of the noisy image, determines and removes the undesired components. Comparisons with a classical method are provided. The experimental results obtained so far are promising.
Article
Electron beam irradiation which is considered a reliable method for tailoring the surface charge of hydroxyapatite is hindered by carbon contamination. Separating the effects of the carbon contamination from those of irradiation-induced trapped charge is important for a wide range of biological applications. In this work we focus on the understandi...
Article
The Bag-of-Features (BoF) paradigm has been introduced to the field of computer vision about a decade ago. Since then, its potential for image classification and retrieval tasks has been demonstrated in numerous experiments, which contributed to BoF approaches becoming well-established in the field. The BoF methods reported to date use mainly spati...
Article
A new advanced sintered composite cutting tool has been developed based on tungsten carbide matrix ligated with cobalt (WC-Co) additivated with tantalum carbide (TaC), titanium carbide (TiC) and niobium carbide (NbC) as grain growth inhibitors. Titanium nitride (TiN), titanium carbonitride (TiCN) and titanium aluminium nitride (TiAlN) coatings were...
Conference Paper
Pairs of images of the same fleld-of-view collected by two complementary Laser Scanning Microscopy (LSM) work-modes are packed together by embedding one image of the pair into the other by reversible watermarking. One image remains visible and the other can be easily extracted at no extra transmission bandwidth cost. The packing keeps together the...
Article
Full-text available
A new method for high-resolution quantitative measurement of the dielectric function by using scattering scanning near-field optical microscopy (s-SNOM) is presented. The method is based on a calibration procedure that uses the s-SNOM oscillating dipole model of the probe-sample interaction and quantitative s-SNOM measurements. The nanoscale capabi...
Conference Paper
It is well known that electrical properties such as local electrostatic charge distribution at biomaterial surface plays a significant role in biological interactions. The methods currently employed in measuring surface charge in biomaterials such as zeta potential or potentiostatic titration, however, can only measure global charge distribution in...
Conference Paper
Colloidal nanoparticles represent an interesting class of materials as they exhibit unique optical, electronic and magnetic properties. Nanoscale optical imaging is essential for observing in detail the optical properties of these materials and for optimizing the associated synthesis procedures in order to make them fit a specific purpose. In the p...
Article
Full-text available
Silicon carbide is one of the most promising materials for power electronic devices capable of operating at extreme conditions. The widespread application of silicon carbide power devices is however limited by the presence of structural defects in silicon carbide epilayers. Our experiment demonstrates that optical second harmonic generation imaging...
Article
Full-text available
The surface properties of hydroxyapatite, including electric charge, can influence the biological response, tissue compatibility, and adhesion of biological cells and biomolecules. Results reported here help in understanding this influence by creating charged domains on hydroxyapatite thin films deposited on silicon using electron beam irradiation...
Article
Full-text available
The dependence of the near-field signal on the dielectric function of a specific material proposes scattering-type near-field optical microscopy (s-SNOM) as a viable tool for material characterization studies. Our experiment shows that specific material identification by s-SNOM is not a straightforward task as parameters involved in the detection s...
Conference Paper
Fluorescence apertureless near-field optical microscopy (FASNOM) gained interest from researchers in the last years because of its promising capabilities: sub-wavelength resolution and ability to exploit the chemical sensitivity of fluorescent tags. FASNOM exploits the fact that metallic structures in close proximity of a fluorophore or a photolumi...
Article
Full-text available
The matching of local descriptors represents at this moment a key tool in computer vision, with a wide variety of methods designed for tasks such as image classification, object recognition and tracking, image stitching, or data mining relying on it. Local feature description techniques are usually developed so as to provide invariance to photometr...
Conference Paper
A novel device based on Silicon photonic crystal waveguides suitable for high density photonic integrated circuits was designed. This device is modeled starting from a previous developed device1, where the main part is consisted of a periodic dielectric multimode waveguide. The novelty of our work is that with our device any basic logic gate functi...
Conference Paper
Scanning near-field microscopy can overcome diffraction limitation by exploiting the evanescent near fields existing close to any illuminated object. For investigations we used a scattering-type near-field optical microscope (s-SNOM). As the main problem of this kind of microscopy is connected with near field detection we focused on the metallic sa...
Article
Full-text available
We experimentally demonstrate the possibility of photorefractive 2D self-focusing in bulk Cerium doped Strontium Barium Niobate (SBN:Ce) directly at telecommunications wavelengths (1.06 μm and 1.55 μm). Although the electro-optic coefficient of SBN is smaller at infrared wavelengths, 2D infrared self-trapping is observed and analyzed versus differe...
Conference Paper
Interactions between two counter-propagating self-trapped beams at infrared wavelengths are experimentally observed in bulk photorefractive semiconductor material InP:Fe. The experimental results are in good concordance with computer simulations. Using these simulations we show that it is possible to develop optical interconnections based on wavegu...
Article
We propose to take advantage of the potential of photo-induced waveguides in photorefractive materials. This technique is very attractive as regards both the employed wavelengths and the possibility of obtaining an alloptical dynamical reconfigurability of the induced guiding structures. We will report on experimental demonstrations of self-induced...

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