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U regionu produžene moždine čoveka nalazi se glavno maslinasto jedro koje pripada donjem maslinastom kompleksu..., Within the region of the human’s medulla oblongata, the main contributor can be found int he section of the principal olivary nucleus as the central part of the Inferior olivary complex...

The Nonlinear Laser Scanning Microscopy (NLSM) contributes to the cell labeling through addressing two main issues: photobleaching and phototoxicity. Moreover, an increase of the penetration depth and a reduction of background autofluorescence are achieved.We have used a multidisciplinary approach combining expertise in material science, nanoparticles synthesis and characterization, cancer cell and tissue labeling, and high resolution imaging, in order to accomplish in vitro imaging of the cancer cells. We have imaged the oral squamous carcinoma cells and human gingival cells. We have demonstrated that we are able to take high contrast images. We have shown position of the nanoparticles in cells, through colocalization of the cell auto-fluorescence and the nanoparticles up-conversion.We plan to improve our abilities through further optimization of the up-converting nanoparticles (smaller and brighter particles) and microscopy technique.

The THz beamline at FLASH, DESY, provides both tunable (1–300 THz) narrow-bandwidth (∼10%) and broad-bandwidth intense (up to 150 uJ) THz pulses delivered in 1 MHz bursts and naturally synchronized with free-electron laser X-ray pulses. Combination of these pulses, along with the auxiliary NIR and VIS ultrashort lasers, supports a plethora of dynamic investigations in physics, material science and biology. The unique features of the FLASH THz pulses and the accelerator source, however, bring along a set of challenges in the diagnostics of their key parameters: pulse energy, spectral, temporal and spatial profiles. Here, these challenges are discussed and the pulse diagnostic tools developed at FLASH are presented. In particular, a radiometric power measurement is presented that enables the derivation of the average pulse energy within a pulse burst across the spectral range, jitter-corrected electro-optical sampling for the full spectro-temporal pulse characterization, spatial beam profiling along the beam transport line and at the sample, and a lamellar grating based Fourier transform infrared spectrometer for the on-line assessment of the average THz pulse spectra. Corresponding measurement results provide a comprehensive insight into the THz beamline capabilities.

Fig. S1. TEM (a) and HRTEM (b) images of amino modified NaYF4:Yb,Er UCNPs. Corresponding FFT/IFFT given as insets in b, confirms that much smaller crystallites notable at the particles surfaces (a) revealed periodic array of cubic alpha phase, (111) plane with d value of 3.140 Å; Fig. S2. XPS spectrum of amino-functionalized NaYF4:Yb,Er UCNPs: survey spectrum and fine-scan spectra of Na 1s, Y 3d, Yb 4d, Er 4d, F 1s and decomposed ones of C 1s, O 1s and N 1s; Fig. S3. Photostability of amino-functionalized up-converting NaYF4:Yb,Er nanoparticles. The emission intensity was traced during 1h

There is a growing interest for development of a facile and reproducible approach for the synthesis of biocompatible lanthanide doped up-converting nanoparticles (UCNPs) for deep tissue imaging and targeted drug delivery. Synthesis of such particles is usually performed through the decomposition of organometallic compounds, followed either with a ligands exchange or with a biocompatible layer coating. In this work, biocompatible NaYF4:Yb,Er (17 mol% Yb; 3 mol% Er) nanoparticles were synthesized by one-pot hydrothermal processing with an assistance of chitosan (Ch) or polyacrylic acid (PAA). Obtained powders were analyzed by X-ray powder diffraction (XRPD, Bruker D8 Discovery), field emission scanning electron microscopy (FE-SEM, Zeiss, DSM 960), transmission electron microscopy (TEM, JEOL JEM 2010), Fourier transform infrared (FTIR, Thermo Scientific Nicolet 6700) and photoluminescence (PL, Spex Fluorolog with C31034 cooled photomultiplier) spectroscopy. The results showed that although both powders crystallize in the same crystal arrangement (cubic, Fm-3m), particles size, shape and optical properties are dependent on the polymer used.

The aim of the current work was to assess obtain a single crystal of calcium tungstate doped with neodymium - (CaWO4:Nd3+), and after that, the crystal was characterized with various spectroscopic methods. The single crystal was grown from the melt using the Czochralski method in air. By optimizing growth conditions, lt 001 gt -oriented CaWO4:Nd3+ crystalc up to 10 mm in diameter were grown. Number of dislocations in obtained crystal was 10(2) per cm(2). Micro hardness was measured with the Vickers pyramid. Anisotropy in lt 001 gt direction was not observed. Selected CaWO4:Nd3+ single crystal was cut into several tiles with the diamond saw. The plates were polished with a diamond paste. The crystal structure is confirmed by X-ray diffraction. The obtained crystal was studied by Raman and infrared spectroscopy. Seven Raman and six IR optical active modes predicted by group theory are observed. FTIR confirmed the occurrence of all the functional groups and bonds in this material. From the FTIR spectrum, a strong peak of 862 cm(-1) has been obtained due to the stretching vibration of WO42- in scheelite structure, and a weak but sharp band at 433 cm(-1) has been noticed due to the metal-oxygen (Ca-O) band. Estimated luminescence lifetime of F-4(5/2) - the I-4(9/2) transition is about 120 mu s; estimated luminescence lifetime of F-4(3/2) - the I-4(9/2) transition is about 140 mu s. All performed investigations show that the obtained CaWO4:Nd3+ single crystal has good optical quality, which was the goal of this work.

In this work, thermal diffusivity of crystalline high-density polyethylene samples of various thickness, and prepared using different procedures, was evaluated by transmission gas-microphone frequency photoacoustics. The samples composition analysis and their degree of crystallinity were determined from the wide-angle X-ray diffraction, which confirmed that high-density polyethylene samples, obtained by slow and fast cooling, were equivalent in composition but with different degrees of crystallinity. Structural analysis, performed by differential scanning calorimetry, demonstrated that all of the used samples had different levels of crystallinity, depending not only on the preparing procedure, but also on sample thickness. Therefore, in order to evaluate the samples thermal diffusivity, it was necessary to modify standard photoacoustic fitting procedures (based on the normalization of photoacoustic amplitude and phase characteristics on two thickness levels) for the interpretation of photoacoustic measurements. The calculated values of thermal diffusivity were in the range of the expected literature values. Besides that, the obtained results indicate the unexpected correlation between the values of thermal diffusivity and thermal conductivity with the degree of crystallinity of the investigated geometrically thin samples. The results indicate the necessity of additional investigation of energy transport in macromolecular systems, as well as the possible employment of the photoacoustic techniques in order to clarify its mechanism.

In this paper we describe the synthesis and characterization of the Sr2CeO4:Eu3+ nanopowder and possibilities of its application for temperature and high pressure sensing. The material was prepared using simple solution combustion synthesis. X-ray powder diffraction (XRD), scanning electron microscope (SEM) and photoluminescence (PL) techniques have been used to confirm and characterize the prepared material. Time resolved analysis of emission spectra was achieved by using the streak camera system. Measured lifetime values of luminescence emission and the intensity ratios of spectral lines were used for determining the calibration curves for remote temperature sensing. We have analyzed sensitivity improvement of the intensity ratio method by using a temporal evolution of emission lines and simulation of delayed gating of one of them. Pressure effects on optical properties of Sr2CeO4: Eu3+ nanophosphor are also investigated.

The gadolinium vanadate doped with samarium (GdVO 4 :Sm 3+ ) nanopowder was prepared by the solution combustion synthesis (SCS) method. After synthesis, in order to achieve the full crystallinity, the material was annealed in air atmosphere at 900°C. Phase identification in the postannealed powder samples was performed by X-ray diffraction, and morphology was investigated by high-resolution scanning electron microscopy (SEM). Photoluminescence characterization of the emission spectrum and time-resolved analysis have been performed using the tunable laser optical parametric oscillator excitation and the streak camera. Several strong emission bands in the Sm 3+ emission spectrum were observed, located at 567 nm ( 4 G 5/2 – 6 H 5/2 ), 604 nm ( 4 G 5/2 – 6 H 7/2 ), and 646 (654) nm ( 4 G 5/2 – 6 H 9/2 ), respectively. The weak emission bands at 533 nm ( 4 F 3/2 – 6 H 5/2 ) and 706 nm ( 4 G 5/2 – 6 H 11/2 ) and a weak broad luminescence emission band of VO 4 3− were also observed by the detection system. We analyzed the possibility of using the host luminescence for two-color temperature sensing. The proposed method is improved by introducing the temporal dependence in the line intensity ratio measurements.

There is a great technological interest in synthesis of lanthanide doped upconverting nanoparticles with specific morphological characteristics and efficient luminescence response suitable for biomedical use [1]. A conventional approach for generation of such particles comprises decomposition of organometallic compoundsin an oxygen-free environment and additional ligand exchange [2,3]. The biocompatible and water soluble NaYF4:Yb,Er@Chitosane particles used in this study were synthesized through facile one-pot hydrothermal synthesis and were characterized using X-ray powder diffraction (XRPD), Fourier-transform infrared (FTIR) spectroscopy, field emission scanning and transmission electron microscopy (FESEM and TEM) and photoluminesce measurement (PL). Due to the presence of the amino groups at their surface these particles exhibit excellent hydrophilic properties and low cytotoxicity against human gingival fibroblasts (HGF), which was proven by MTT assay. Furthermore, upon 980 nm laser irradiation the as-prepared particles were successfully used for in-vitro visualization of the primary cell cultures of head and neck squamous carcinoma cells (HNSCC). In a NaYF4:Yb,Er phase upconversion is enabled by the sequential absorption of two or more near-infrared photons by Yb3+ and subsequent energy transfer to the long-lived metastable electron states of Er3+ which produces luminescence emission at visible spectra after relaxation.

The present study describes utilization of two photon excitation fluorescence (2PE) microscopy for visualization of the hemoglobin in human and porcine erythrocytes and their empty membranes (i.e., ghosts). High-quality, label-and fixation-free visualization of hemoglobin was achieved at excitation wavelength 730 nm by detecting visible autofluorescence. Localization in the suspension and spatial distribution (i.e., mapping) of residual hemoglobin in erythrocyte ghosts has been resolved by 2PE. Prior to the 2PE mapping, the presence of residual hemoglobin in the bulk suspension of erythrocyte ghosts was confirmed by cyanmethemoglobin assay. 2PE analysis revealed that the distribution of hemoglobin in intact erythrocytes follows the cells' shape. Two types of erythrocytes, human and porcine, characterized with discocyte and echinocyte morphology, respectively, showed significant differences in hemoglobin distribution. The 2PE images have revealed that despite an extensive washing out procedure after gradual hypotonic hemolysis, a certain amount of hemoglobin localized on the intracellular side always remains bound to the membrane and cannot be eliminated. The obtained results open the possibility to use 2PE microscopy to examine hemoglobin distribution in erythrocytes and estimate the purity level of erythrocyte ghosts in biotechnological processes.

Spider dragline silk was coated with pure as well as Eu-doped ceria nanopowders at the room temperature. The treatment was done by immersion of the spider silkmesh into aqueous solutions of cerium nitrate (Ce(NO3)(3)) and ammonium hydroxide (NH4OH). Depending on the relationship between Ce3+ ion and ammonium hydroxide concentration, coated fibers exhibited a different thickness. Obtained materials were studied by means of FESEM. It was found that ceria nanoparticles of average size of 3 nm were coated along spider thread. X-ray diffraction (XRD) and selected-area electron diffraction (SAED) confirmed crystal nature of nanoparticle coating of spider silk. By using Williamson-Hall plots, crystallite size and strain were estimated. EDS measurement confirmed the presence of Eu in spider-Eu-doped ceria composite, and according to FTIR analysis, the interaction between CeO2 and spider silk was proposed. The morphology of obtained composite was observed by TEM. The photoluminescence emission spectra of spider silk coated with Eu-doped ceria were measured with two different excitations of 385 and 466 nm. The two-photon excited auto-fluorescence of spider silk coated with Eu-doped ceria was detected using a nonlinear laser scanning microscope. Obtained composite has a potential as a fluorescent labeling material in diverse applications.

In this work we investigated the photoluminescence properties of Y2O3: Er3+, Eu3+ as a function of temperature and the possibility to use this material as a temperature sensor. Photoluminescence emission measurements with 532 nm laser excitation were recorded in the temperature range from 303 up to 573 K. The measured intensity ratio of erbium S-4(3/2) - GT I-4(15/ 2) and europium D-5(0) - GT F-7(2) emission lines was used for determination of the temperature calibration curve. These emission lines are intense, narrow and well defined. The distance between the lines, being 47 nm, can be easily measured even with a low-resolution spectrometer. The calculated relative sensitivity of the temperature sensor was 1.4% K-1 at 303 K, in the physiological temperature range, meaning that it could be successfully applied in biological studies.

A minimum volume photoacoustic (PA) cell, employed as an acoustic resonator, is presented. A model of the PA cell transfer function, as a combination of two Helmholtz resonators, is derived. Frequency PA response is described as the product of theoretically derived pressure variation and the transfer function of the PA cell. The derived model is applied to the frequency PA measurements, performed on laser-sintered polyamide. It is shown that the derived model explains the occurrence of resonant peaks in the high-frequency domain ( GT 10 kHz), in both amplitude and phase measurements, obtained by a gas-microphone minimal volume PA cell. The implementation of the model in the growing possibilities of sample characterization using gas-microphone PA cell is discussed.

Dysprosium (Dy3+ ions) doped YAG nanopowders were prepared by the solution combustion synthesis (SCS) method and undoped yttrium aluminum garnet (YAG, Y3Al5O12) single crystal was grown by the Czochralski technique. The structure of the prepared materials has been confirmed and characterized using X-ray powder diffraction (XRD), scanning electron microscope (SEM), Raman and photoluminescence (PL) spectroscopy. PL spectra were acquired using Optical Parametric Oscillator (OPO) excitation tuned at 350 nm. Several emission bands in Dy3+ emission spectrum were observed in the blue (470-500 nm), yellow (560-600 nm), red (660-685 nm) and infra-red (750-780 nm) regions, corresponding to F-4(9/2)-H-6(15/2), F-4(9/2)-H-6(13/2), F-4(9/2)-H-6(11/2), F-4(9/2)-(H-6(9/2) + H-6(11/2)) transitions in the 4f levels of Dy3+ ions, respectively. By using the Commission Internationale de lEclairage (CIE) chromaticity diagram of emission spectra it has been shown that this material can be used as a source of a white light. The result of lifetime analysis of the F-4(9/2) level in dysprosium ion has been reported, as well. (C) 2015 Elsevier B.V. All rights reserved.

Nanopowders based on gadolinium zirconium oxide (Gd2Zr2O7) doped by europium ions (Eu3+) were successfully prepared using a flame combustion method. This material is suitable for various optical devices. The structure of prepared materials has been confirmed and characterized using X-ray powder diffraction (XRD), scanning electron microscope (SEM) and photoluminescence (PL) techniques. The luminescence properties of synthesized nanopowders were characterized by emission spectra and luminescence lifetimes by using the streak camera system. PL spectra were obtained at three different excitation wavelengths (Optical Parametric Oscilator (OPO) at 360 nm, laser diode at 365 nm and Ar laser line at 514.5 nm). The strong emission lines at 611 nm and 630 nm corresponding to the D-5(0) - GT F-7(2) long lived transition could be used as a new red light source in optical devices. (C) 2014 Elsevier B.V. All rights reserved.

The open-cell photoacoustic signal measured in the transmission configuration for aluminum thin plates with thicknesses of 280 mu m, 197 mu m, and 112 mu m is experimentally and theoretically analyzed, in the 20 Hz-7 kHz modulation frequency range. It is shown that the observed differences between the predictions of the standard thermoelastic model and the experiment data of both the amplitude and phase of the photoacoustic signal can be overcome by considering the aluminum samples coated with a thin layer of black paint as volume-absorber materials. This new approach provides a quite good agreement with the obtained experimental data, in the whole frequency range, and yields an effective absorption coefficient of (16 +/- 2) mm(-1), for a 280 mu m-thick sample. The introduction of the finite absorption coefficient led to the correct ratio between the thermal diffusion and thermoelastic components of the photoacoustic signal. Furthermore, it is found that the volume-absorber approach accurately describes the behavior of the amplitude, but not that of the phase recorded for a 112 mu m-thick sample, due to its relatively strong thermoelastic bending, which is not considered by this theory. Within the approximation of the small bending, the proposed volume-absorber model provides a reliable description of the photoacoustic signal for Al samples thicker than 112 mu m, and extends the applicability of the classical opaque approach. (C) 2015 AIP Publishing LLC.

Methods for photoacoustic signal measurement, rectification, and analysis for 85 mu m thin Si samples in the 20-20 000 Hz modulation frequency range are presented. Methods for frequency-dependent amplitude and phase signal rectification in the presence of coherent and incoherent noise as well as distortion due to microphone characteristics are presented. Signal correction is accomplished using inverse system response functions deduced by comparing real to ideal signals for a sample with well-known bulk parameters and dimensions. The system response is a piece-wise construction, each component being due to a particular effect of the measurement system. Heat transfer and elastic effects are modeled using standard Rosencweig-Gersho and elastic-bending theories. Thermal diffusion, thermoelastic, and plasmaelastic signal components are calculated and compared to measurements. The differences between theory and experiment are used to detect and correct signal distortion and to determine detector and sound-card characteristics. Corrected signal analysis is found to faithfully reflect known sample parameters. (C) 2015 AIP Publishing LLC.