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High-resolution imaging of alpha particles is required in the detection of alpha radionuclides in cells or small organs for the development of radio-compounds for targeted alpha-particle therapy or other purposes. We developed an ultrahigh resolution, real time alpha-particle imaging system for observing the trajectories of alpha particles in a scintillator. The developed system is based on a magnifying unit and a cooled electron multiplying charge-coupled device (EM-CCD) camera, combined with a 100-µm-thick Ce-doped Gd3Al2Ga3O12 (GAGG) scintillator plate. Alpha particles from an Am-241 source were irradiated to the GAGG scintillator and imaged with the system. Using our system, we measured the trajectories of the alpha particles having different shapes in real time. In some of these measured trajectories, the line shapes of the alpha particles that flew in the GAGG scintillator were clearly observed. The lateral profiles of the alpha-particle trajectories were imaged with widths of ~ 2 µm. We conclude that the developed imaging system is promising for research on targeted alpha-particle therapy or other alpha particle detections that require high spatial resolution.

Cell lines are powerful tools for research into liver function at the molecular level. However, they are generally unsuitable for rigorously assessing the effects of amino acid composition, because many lines require serum-containing medium for their maintenance. Here, we aimed to investigate the effects of ornithine and arginine, which are included in the characteristic metabolic process in hepatocyte, on a human hepatoma-derived cell line (FLC-4) that can be cultured in serum-free medium. FLC-4 cells were cultured under the following three conditions: + ornithine/ – arginine, – ornithine/ – arginine, and –ornithine/ + arginine. Albumin expression evaluated by quantitative polymerase chain reaction and enzyme-linked immunosorbent assay and showed no obvious differences based on the presence of ornithine or arginine. However, the mRNA levels of two liver-enriched transcription factors (CEBPB and HNF1A), which are involved in regulating albumin expression, were significantly higher in cells grown in medium-containing arginine than that in cells grown in ornithine-containing medium. Western blotting showed that the levels both activating and inhibitory C/EBPβ isoforms were significantly increased in cells grown in arginine medium. Furthermore, we have found that depletion of both ornithine and arginine, the polyamine sources, in the medium did not cause polyamine deficiency. When ornithine and arginine were depleted, albumin production was significantly reduced at the mRNA level, CEBPB mRNA levels were increased, and the level of activating form of C/EBPβ was increased. The results of this study suggest that in hepatocyte, these two amino acids might have different functions, and because of which they elicit disparate cellular responses. Electronic supplementary material The online version of this article (10.1007/s13577-020-00383-1) contains supplementary material, which is available to authorized users.

This paper reports on the preparation of undoped cesium hafnium chloride (Cs2HfCl6) and study of its thermal properties. The Cs2HfCl6 is considered, due to its excellent scintillation properties, as a promising candidate for cost-effective radiation detectors with potential to replace traditional halide scintillators, e.g., NaI:Tl and CsI:Tl. The Cs2HfCl6 material was successfully synthesized from a cesium chloride and a hafnium chloride mixed together in stoichiometric ratio. The presence of only one crystalline phase of the Cs2HfCl6 in the material was confirmed by the X-ray diffraction analysis. The simultaneous non-isothermal differential scanning calorimetry and thermogravimetry (DSC–TG) of the synthesized material under nitrogen atmosphere, vacuum, and in enclosed system was performed. The Cs2HfCl6 decomposition and melting of CsCl–Cs2HfCl6 mixture under nitrogen and vacuum were observed. On the contrary, the DSC measurement of the cesium hafnium chloride in enclosed system showed only one endothermic peak related to the congruent melting point. Furthermore, the repeated DSC–TG measurements to investigate the materials’ stability in enclosed system were carried out as well.

Undoped and Nb-doped SrTiO3/TiO2 (STO/TO) eutectic solids were fabricated from the melt at a eutectic point of STO and TO by unidirectional solidification. Fabricated undoped and Nb:STO/TO eutectic solids were composed of the TiO2 rod-like and the SrTiO3 matrix phases, and the periodic and uniform eutectic morphology could be achieved in the Nb:STO/TO eutectic solids by stable control of the liquid–solid interface during the fabrication. The thermal conductivity of the Nb:STO/TO eutectic solid was less than half of that of the Nb:STO single crystal owing to the decrease of the lattice thermal conductivity by phonon scattering at the grain boundaries. The figures of merit ZT’s of the Nb:STO/TO eutectic solid, parallel and perpendicular to the growth direction, were ∼ 0.007 and ∼ 0.0004, respectively. The small ZT’s are attributable to the higher electrical resistivity originating from the insufficient carrier doping and high electrical resistivity of the TO phase.

In this study, Eu and Ce doped LiSrI3 single crystals were explored and the scintillation performance was reported at the first time. Eu and Ce doped LiSrI3 single crystals were grown by the Bridgman–Stockbarger method in a quartz ampoule with 3 mm inner diameter. Growth rate was 0.06 mm/min. Circular samples with 1 mm thickness were obtained from the grown crystal. The grown Eu doped LiSrI3 crystal demonstrated Eu2+ 4f–5d emission peak at 420 nm under alpha-ray excitation. In the case of Ce doped one, double emission peaks at 360 and 400 nm were observed. The light yield of the Eu doped LiSrI3 was around 35,000 photon/MeV for 662 keV gamma-ray and 24,000 photon/5.5 MeV for alpha-ray. Energy resolution of the Eu doped LiSrI3 was 5.2%@662 keV. Scintillation decay time of the grown Ce and Eu doped LiSrI3 under 662 keV gamma-ray was 23.8 ns (50%) 212 ns (50%) and 545 ns 100%, respectively.

Ce-doped garnet-type single crystals with improved dopant distribution were grown by the micro-pulling-down method using a modified Iridium crucible and effects of dopant distribution improvement on the optical and scintillation properties were investigated. Ce-doped Y3Al5O12 (Ce:YAG) and Gd3(Ga,Al)5O12 (Ce:GGAG) single crystals with improved dopant distribution could be grown by a Iridium crucible with five capillaries (5C). The Ce:YAG and Ce:GGAG single crystals (5C) showed higher transmittance than the single crystals grown by an original Iridium crucible with one capillary (1C). In addition, a clear photo-peak could be observed in the pulse-height spectrum of the Ce:YAG single crystal (5C) under γ-ray irradiation while there was no peak in the spectrum of the Ce:YAG single crystal (1C).

Li-containing materials can be applied as neutron scintillators, and LiBaF3 can discriminate neutron and gamma rays. Moreover, LIF/LiBaF3 can have higher cross section of thermal-neutron capture compared with LiBaF3. In this study, LiF (82.5 mol%) and (Ba1−x RE x )F2 (17.5 mol%, RE = Ce and Eu, x = 0.002) eutectic crystals, LiF/RE:LiBaF3, were grown by the micropulling down method with different pulling rates (growth rate) in order to observe the eutectic structure. Lamellar microstructure was formed for each pulling rate. LiF/Ce:LiBaF3 excited by 5.5-MeV alpha rays had a broad peak at ~350 nm corresponding to 5d–4f transition of Ce3+. On the other hand, LiF/Eu:LiBaF3 had two scintillation processes; a sharp emission was originated from 6P7/2 → 8S7/2 transitions in the 4f electronic configuration of Eu2+ at 360 nm, and a broad one was attributed to Eu2+ trapped exciton recombination at 400–450 nm. Since scintillation light was observed for these materials, these scintillators are sensitive to neutrons.

During exercise, tidal volume initially contributes to ventilatory responses more than respiratory frequency, and respiratory frequency then increases rapidly while tidal volume stabilizes. Dyspnea intensity is also known to increase in a threshold-like manner. We tested the possibility that the threshold of tachypneic breathing is equal to that of dyspnea perception during cycle ergometer exercise (n = 27). Dyspnea intensity was scored by a visual analog scale. Thresholds were expressed as values of pulmonary O2 uptake at each breakpoint. Dyspnea intensity and respiratory frequency started increasing rapidly once the intensity of stimuli exceeded a threshold level. The thresholds for dyspnea intensity and for occurrence of tachypnea were significantly correlated. An intraclass correlation coefficient of 0.71 and narrow limits of agreement on the Bland–Altman plot indicated a good agreement between these thresholds. These results suggest that the start of tachypneic breathing coincides with the threshold for dyspnea intensity during cycle ergometer exercise.

A hybrid two-phase model, incorporating lattice Boltzmann method (LBM) and finite difference method (FDM), was developed to investigate the coalescence of two drops during their thermocapillary migration. The lattice Boltzmann method with a multi-relaxation-time (MRT) collision model was applied to solve the flow field for incompressible binary fluids, and the method was implemented in an axisymmetric form. The deformation of the drop interface was captured with the phase-field theory, and the continuum surface force model (CSF) was adopted to introduce the surface tension, which depends on the temperature. Both phase-field equation and the energy equation were solved with the finite difference method. The effects of Marangoni number and Capillary numbers on the drop’s motion and coalescence were investigated.

cited By 1; International audience; Yttrium aluminum garnet (YAG)-based ceramics represent a valuable alternative to single crystals as active media in laser devices for specific applications. In this connection, the 1.5-1.65 μm emission channel of Er3+-doped YAG is of particular importance for the realization of diode pumped solid state lasers operating in the so-called 'eye-safe' region. A well-known drawback of this material is related to its small absorption cross section in correspondence to the diode pumping radiation at 940-980 nm. However, its emission performance can be significantly improved through sensitization with Yb3+ ions that can efficiently absorb the excitation radiation and transfer it to the Er3+ ions. This work deals with the fabrication of polycrystalline YAG co-doped with Er3+ and Yb3+ ions from oxide powders via solid state sintering in high vacuum conditions and its microstructural analysis by transmission electron microscopy-energy-dispersive x-ray spectroscopy to determine the dopants distribution and to assess their influence on the sintering process and on the spectroscopic properties. For this purpose, the absorption and emission spectra of the prepared material have been measured and compared with those of a single crystal having the same composition, appositely prepared by the micro-pulling down method. Suitable calculations have been finally carried out to verify the effective perspectives of application of the investigated ceramics as active lasing medium. © Materials Research Society 2014.

Pituitary adenylate cyclase-activating polypeptide (PACAP) has been known as a neuroprotectant agent in several retinal injury models. However, a detailed mechanism of this effect is still not well understood. In this study, we examined the retinoprotective effects and associated underlying mechanisms of action of PACAP in the mouse N-methyl-D-aspartic acid (NMDA)-induced retinal injury model, focusing on the relationship between PACAP and retinal microglia/macrophage (MG/MΦ) status. Adult male C57BL/6 mice received an intravitreal injection of NMDA to induce retinal injury. Three days after NMDA injection, the number of MG/MΦ increased significantly in the retinas. The concomitant intravitreal injection of PACAP suppressed NMDA-induced cell loss in the ganglion cell layer (GCL) and significantly increased the number of MG/MΦ. These outcomes associated with PACAP were attenuated by cotreatment with PACAP6-38, while the beneficial effects of PACAP were not seen in interleukin-10 (IL-10) knockout mice. PACAP significantly elevated the messenger RNA levels of anti-inflammatory cytokines such as transforming growth factor beta 1 and IL-10 in the injured retina, with the immunoreactivities seen to overlap with markers of MG/MΦ. These results suggest that PACAP enhances the proliferation and/or infiltration of retinal MG/MΦ and modulates their status into an acquired deactivation subtype to favor conditions for neuroprotection.

Pituitary adenylate cyclase-activating polypeptide (PACAP) exerts a neuroprotective action against ischemic damage. This action is mediated by the interleukin-6 (IL-6) pathway. However, as the expression patterns of PACAP receptors and IL-6 following ischemia are not understood, we evaluated them in the mouse hippocampus in response to ischemia induced by bilateral common carotid artery occlusion. Real-time PCR determination of PAC1R mRNA expression in the hippocampus was significantly elevated on day 7 after ischemia. VPAC1R mRNA expression was significantly decreased 3 days after the ischemic episode, while VPAC2R mRNA expression showed a nonsignificant tendency to increase on day 7. IL-6 mRNA expression was significantly increased on day 3 and peaked on day 7 after ischemia. The mRNA expression of activity-dependent neuroprotective protein, which is a neuroprotective factor stimulated by PACAP, remained virtually unchanged in response to ischemia. IL-6 immunoreactivity was detected in the CA1 pyramidal cell layer and colocalized with the neuronal marker NeuN on day 1 after ischemia. On day 3, irregularly shaped IL-6-immunopositive cells colocalized with the astrocytic marker glial fibrillary acidic protein but not with the microglial marker Iba1. PAC1R immunoreactivity co-labeled with IL-6 immunoreactivity. These results suggest that PACAP could stimulate IL-6 secretion by neurons during the acute phase after an ischemic episode and thereafter by astrocytes during the subacute phase.

The micro-pulling-down technique is a crystal growth method that has been mostly developed since 1992. The general scheme of the growth system is relatively simple: the melt (oxide, fluoride, metal) residing in a crucible is transported in downward through microcapillary channel(s) made in the bottom of the crucible. Two driving forces (capillary action and gravity) support the delivery of the melt to the liquid/solid growth interface formed under the crucible due to a properly established temperature gradient. Appropriate configuration of the crucible bottom allows for controlling of the crystal shape (fibers, rods, tubes, plates) and the dimensions of the crystals' cross sections that range approximately from 0.1 to 10 mm. A great number of scientifically and industrially important optical crystal fibers have been successfully produced using this method.

Fabrication of wurtzite-type gallium nitride (GaN) thick films on HPVE-grown {0001} GaN substrates under moderate ammonothermal conditions is reported. Supercritical ammonia (NH3) as solvent and the mineralizer ammonium chloride (NH4Cl) is employed for temperature and pressure conditions of 400–550 °C and ≤135 MPa, respectively. Growth rates of 30 μm per day over long-term growth runs were obtained. The effect of surface morphology of the substrate on homoepitaxial nucleation of GaN films prepared from ammonoacid solutions is investigated. Two-dimensional nucleation is obtained for substrates etched by hot concentrated KOH prior film growth. In this case the interface between film and the ( $$ 000\overline 1 $$ ) substrate does not show any signs of voids or island nucleation. Cracking pattern reveals similar mechanical-elastical properties for film and substrate.

The photoluminescence spectra of the rod-shaped pure and Ti-doped MgAl2O4 single crystals, grown by the micro-pulling-down (μ-PD) method, have been systematically investigated under high-intensity pulsed Nd3+: YAG laser excitation in the ultraviolet (UV) region (266 nm). The chemical properties of the grown crystals under reducing argon atmosphere will be reported and the annealing effect under oxidizing atmosphere will be discussed. The room temperature luminescence properties of Ti-doped MgAl2O4 single crystals were performed before and after annealing as a function of the titanium concentration. Three broad bands absorption in the UV/VIS (visible) spectral regions and a broadband visible blue emission were observed from Ti-doped MgAl2O4. An estimation of the decay time value of theses emissions was determined from the time-resolved spectra and the energies of the vibrational modes of the MgAl2O4 crystal are obtained from the infrared spectra.

To investigate the directional dependence of the Faraday effect in terbium–scandium–aluminum garnet (TSAG) single crystals, grown by the Czochralski method, the Verdet constant was measured at 〈111〉, 〈110〉, and 〈100〉 orientations. Extinction ratio and magnetic susceptibility were measured. From the linear dependence of the Verdet constant and inverse wavelength square 1/λ2, 〈111〉 direction shows the highest value of Verdet constant (for λ⋅ = 649.1 nm, Vav = 8.256 × 10−3 deg · Oe−1 · cm−1). Significant anisotropy of magnetic susceptibility was not observed. The extinction ratio of TSAG shows the highest value for 〈111〉 orientation 38.7 dB, which implies that it can be used as an optical isolator.

The superior strength at high temperature of directionally solidified eutectic materials, the so-called melt-growth composites, such as sapphire–YAG is attributed in large measure to their “Chinese script” microstructure. The mechanical properties of fibers of such materials, grown for example by the micro-pulling-down technique, depend strongly on the nature of the morphology at the surface. Using atomic force microscopy to study fibers grown by the micro-pulling-down technique, we show that the script microstructure extends to the surface. Atomic force microscopy revealed that the surface differs from the bulk in both volume ratio and domain size, which could not be observed by SEM. The surface volume ratio varies with growth rate, and tends to approach the properties of the bulk as the growth rate increases.

High quality oxide and fluoride single crystals for optical, piezoelectric and other applications have been grown by advanced crystal growth techniques. La3Nb0.5Ga5.5O14 and La3Ta0.5Ga5.5O14 piezoelectric single crystals of size and quality comparable to La3Ga5SiO14 (langasite), have been produced. The piezoelectric and device properties of the crystals were investigated. A search for new langasite-type materials was also performed. Growth conditions of (La,Sr)(Al,Ta)O3 and Ca8La2(PO4)6O2 single crystals are discussed. These crystals have excellent lattice matching with GaN, a promising material for optoelectronic devices. Promising optical micro-crystals—K3Li2Nb5O15, KNbO3 and Y3Al5O12—and new structural materials, Al2O3Y3Al5O12 eutectic fibers, have been grown by the micro-pulling-down (μ-PD) technique. The advantages of the μ-PD technique have been shown. Ce-doped fluoride single crystals—LiCaAlF6, LiYF4 and BaLiF3—have been grown for solid state UV laser applications. Growth results and optical characterizations are discussed.

The optical properties of undoped RE2O3 (RE = Lu, Sc, Y) sesquioxides, which were prepared by different methods, are reported. Luminescent characteristics, including emission, excitation spectra as well as luminescence decay kinetics were studied in a wide spectral range. The main intrinsic emission bands are located in ultraviolet region and the origin of these luminescent bands is different owing to the different electronic structure. In present paper, the spectral characteristics of these samples are considered and compared with those studied before; the origin of the intrinsic bands is discussed.

Chemical doping of a small amount (0.02∼0.3) of rhenium (Re) ion into HgBa2Can−1CunOy(n=1∼4) has been studied. The flux pinning strength in these Hg-based superconductors is significantly enhanced compared to the undoped parent materials. Neutron diffraction analysis of representative samples (n=3) revealed that Re partially substitutes the Hg-site with octahedrally fully coordinated oxygen atoms, giving rise to the stabilization of Hg(Re)O layer and reduction of this blocking layer thickness. Associated with the expected hybridization of Re-5d and O-2p orbitals and possible metallization of the Hg(Re)O layer, the improved flux pinning behavior is considered to be caused by the decrease of the electromagnetic anisotropy and the enhanced interlayer superconducting coupling strength.

Shape-controlled CaF2 and sapphire crystals were grown by a micro-pulling-down (μ-PD) method and the crystallinities were investigated. By the μ-PD method with crucibles which have special configurations, circular tube-shaped CaF2 crystal, square tube-shaped CaF2 crystal and square tube-shaped sapphire crystal with high transparency were obtained. The grown crystals indicated a single phase of CaF2 and Al2O3 in the XRD measurements. X-ray rocking curve of square tube-shaped sapphire indicated the crystal has no mosaic structure in the crystal and it has high crystallinity comparable to crystals grown by Cz method.

Phase formation in ternary system of complex Sc, Na and Li phosphates was studied at 950°C and synthesis of new phases of definite composition was carried out. Obtained samples were investigated with X-ray powder diffraction, infrared and impedance spectroscopy. Compositions of fields of homogeneity with the NASICON-like structure were discovered. Temperature dependency of ionic conductivity was measured.

(Ybx Y1-x)2O3 (x = 0.0, 0.005, 0.05, 0.08 and 0.15) promising single crystal laser rods of 4.2 mm in diameter and 15–20 mm in length have been grown from the rhenium crucible by the micro-pulling-down method in Ar + H2(3–4%) atmosphere. Linear decrease of lattice constant with the increase of Yb3+-content was observed. High homogeneity of the Yb3+-dopant distribution has been demonstrated. Absorption, emission and Raman spectra have been recorded and decay time was approximated.

Some oxide eutectic materials, such as sapphire/YAG, display an intricate “Chinese script” microstructure which strongly influences properties such as mechanical strength. We used the micro pulling-down technique to grow fibers of a series of such materials at rates over 20 mm/min, giving a uniform microstructure with a characteristic size as low as 150 nm. Bulk and surface characteristics of this microstructure were investigated by electron and atomic force microscopy. Smaller microstructure size gave higher tensile strength at 1500°C. Annealing of the fibers produced some coarsening of the microstructure, but increased the strength at lower temperatures.