Size-Dependent Persistent Luminescence of YAGG:Cr3+ Nanophosphors

In the current work, YAGG:Cr³⁺ nanophosphors were synthesized by the Pechini method and then annealed at different temperatures in the range 800–1300 °C. The structure and morphology of the samples were characterized by X-ray Powder Diffraction (XRPD). The lattice parameters and average crystalline sizes as site occupation by Al³⁺ and Ga³⁺ ions were calculated from the Rietveld refinement data. To investigate the effect of crystalline size of the materials on their optical properties: excitation and emission spectra were recorded and analyzed. Finally, the effect of crystalline size on the probability of carrier recombination leading to PersL was determined experimentally with thermoluminescence analyses. The T_max-T_stop method was applied to determine the trap type and particle size (calcination temperature) effect on their redistribution. A correlation between structural changes and trap redistribution was found. In particular, the extinction of high-temperature TL maximum with increasing annealing temperatures is observed, while low-temperature TL maximum increases and reaches a maximum when the lattice parameter reaches saturation.     

Effectiveness of inhaled hypertonic saline application for sputum induction to improve Mycobacterium tuberculosis identification in patients with pulmonary tuberculosis

Wiener Medizinische Wochenschrift - This study assessed the effectiveness and diagnostic significance of hypertonic saline sputum induction for improving Mycobacterium tuberculosis (MTB) detection....     

The relationship between angle kappa and astigmatism after phacoemulsification with implanting of spherical and aspheric intraocular lens

Purpose:To determine the significance of any association between either change in angle kappa (K°) or the rectilinear displacement (L, mm) of the first Purkinje image relative to the pupil center and unexpected changes in astigmatism after phacoemulsification.Methods:Orbscan II (Bausch and Lomb) measurements were taken at 1, 2, and 3 months after unremarkable phacoemulsification in patients implanted with spherical (group 1, SA60AT, Alcon) or aspheric (group 2, SN60WF, Alcon) nontoric IOLs. The outputs were used to calculate L. Astigmatism, measured by autorefractometry and subjective refraction, was subjected to vector analysis (polar and cartesian formats) to determine the actual change induced over the periods 1–2 and 2–3 months postop.Results:Chief findings were that the mean (n, ±SD, 95%CI) values for L over each period were as follows: Group 1, 0.407 (38, ±0.340, 0.299–0.521), 0.315 (23, ±0.184, 0.335–0.485); Group 2, 0.442 (45, ±0.423, 0.308–0.577), 0.372 (26, ±0.244, 0.335–0.485). Differences between groups were not significant. There was a significant linear relationship between (A) the change in K (ΔK = value at 1 month-value at 2 months) and K at 1 month (x), where ΔK =0.668-3.794X (r = 0.812, n = 38, P = <0.001) in group 1 and ΔK = 0.263x -1.462 (r = 0.494, n = 45, P = 0.002) in group 2, (B) L and the J₄₅ vector describing the actual change in astigmatism between 1 and 2 months in group 2, where J₄₅ (by autorefractometry) =0.287L-0.160 (r = 0.487, n = 38, P = 0.001) and J₄₅ (by subjective refraction) =0.281L-0.102 (r = 0.490, n = 38, P = 0.002), and (C) J₄₅ and ΔK between 2 and 3 months in group 2, where J₄₅ (by subjective refraction) =0.086ΔK-0.063 (r = 0.378, n = 26, P = 0.020).Conclusion:Changes in the location of the first Purkinje image relative to the pupil center after phacoemulsification contributes to changes in refractive astigmatism. However, the relationship between the induced change in astigmatism resulting from a change in L is not straightforward.     

Folate receptor targeting silica nanoparticle probe for two-photon fluorescence bioimaging

Narrow dispersity organically modified silica nanoparticles (SiNPs), diameter ~30 nm, entrapping a hydrophobic two-photon absorbing fluorenyl dye, were synthesized by hydrolysis of triethoxyvinylsilane and (3-aminopropyl)triethoxysilane in the nonpolar core of Aerosol-OT micelles. The surface of the SiNPs were functionalized with folic acid, to specifically deliver the probe to folate receptor (FR) over-expressing Hela cells, making these folate two-photon dye-doped SiNPs potential candidates as probes for two-photon fluorescence microscopy (2PFM) bioimaging. In vitro studies using FR over-expressing Hela cells and low FR expressing MG63 cells demonstrated specific cellular uptake of the functionalized nanoparticles. One-photon fluorescence microscopy (1PFM) imaging, 2PFM imaging, and two-photon fluorescence lifetime microscopy (2P-FLIM) imaging of Hela cells incubated with folate-modified two-photon dye-doped SiNPs were demonstrated.     

The effect of corneal crosslinking on the rigidity of the cornea estimated using a modified algorithm for the Schiøtz tonometer

Purpose:The aim of this study was to test a method for estimating corneal rigidity before and after cross-linking (CXL) using a Schiøtz tonometer.Methods:The study was performed in the Kyiv City Clinical Ophthalmological Hospital “Eye Microsurgical Center”, Ukraine. This was a prospective, consecutive, randomized, masked, case-by-case, clinical study. Corneal rigidity, indicated by the gradient (G) between lg applied weight and corresponding lg scale reading during Schiøtz tonometry, were obtained by increasing (A-mode) then reducing (D-mode) weights by two operators [A] in keratoconus, post-CXL and control subjects for estimation of (i) interoperator and (ii) intersessional errors, (iii) intergroup differences; [B] before and after CXL. Central corneal thickness CCT was measured by scanning slit pachymetry. ANOVA, t tests, linear regression were the statistical tools used.Results:Average interoperator difference (ΔG) was –0.120 (SD = ±0.294, 95%CI = –0.175 to –0.066). A significant correlation between ΔG and the mean of each pair of G values was found (r = –0.196, n = 112, P = 0.038). Intersessional differences in mean G values were insignificant (P > 0.05). There was a significant correlation between G at first session (X₁) and difference between sessions (ΔG) [Operator 1, ΔG = 0.598x₁–0.461, r = 0.601, n = 27, P = 0.009]. Significant intergroup differences in G were found (Operator 1, one-way ANOVA, F = 4.489, P = 0.014). The difference (Δ) between the pre-(X₂) and post-CXL treatment G values was significantly associated with the pre-CXL treatment value (Operator 1, Δ = 1.970x₂-1.622, r = 0.642, n = 18, P = <.001). G values were correlated with CCT in keratoconus and post-CXL.Conclusion:Corneal rigidity (G) estimated using the Schiøtz tonometer can be useful for detecting changes after CXL. However, G values are linked to CCT, can vary from time-to-time and the procedure is operator dependent.     

Fluorescence polarization of green fluorescence protein

We report here the striking anisotropy of fluorescence exhibited by crystals of native green fluorescence protein (GFP). The crystals were generated by water dialysis of highly purified GFP obtained from the jellyfish Aequorea. We find that the fluorescence becomes six times brighter when the excitation, or emission, beam is polarized parallel (compared with perpendicular) to the crystal long axis. Thus, the major dipoles of the fluorophores must be oriented very nearly parallel to the crystal long axis. Observed in a polarizing microscope between parallel polars instead of either a polarizer or analyzer alone, the fluorescence polarization ratio rises to an unexpectedly high value of about 30:1, nearly the product of the fluorescence excitation and emission ratios, suggesting a sensitive method for measuring fluorophore orientations, even of a single fluorophore molecule. We have derived equations that accurately describe the relative fluorescence intensities of crystals oriented in various directions, with the polarizer and analyzer arranged in different configurations. The equations yield relative absorption and fluorescence coefficients for the four transition dipoles involved. Finally, we propose a model in which the elongated crystal is made of GFP molecules that are tilted 60 degrees to align the fluorophores parallel to the crystal long axis. The unit layer in the model may well correspond to the arrangement of functional GFP molecules, to which resonant energy is efficiently transmitted from Ca2+-activated aequorin, in the jellyfish photophores.     

Intermetallic Phases Identification and Diffusion Simulation in Twin-Roll Cast Al-Fe Clad Sheet

Aluminium steel clad materials have high potential for industrial applications. Their mechanical properties are governed by an intermetallic layer, which forms upon heat treatment at the Al-Fe interface. Transmission electron microscopy was employed to identify the phases present at the interface by selective area electron diffraction and energy dispersive spectroscopy. Three phases were identified: orthorhombic Al₅Fe₂, monoclinic Al₁₃Fe₄ and cubic Al₁₉Fe₄MnSi₂. An effective interdiffusion coefficient dependent on concentration was determined according to the Boltzmann–Matano method. The highest value of the interdiffusion coefficient was reached at the composition of the intermetallic phases. Afterwards, the process of diffusion considering the evaluated interdiffusion coefficient was simulated using the finite element method. Results of the simulations revealed that growth of the intermetallic phases proceeds preferentially in the direction of aluminium.     

Raman and X-ray Photoelectron Spectroscopic Study of Aqueous Thiol-Capped Ag-Zn-Sn-S Nanocrystals

The synthesis of (Cu,Ag)-Zn-Sn-S (CAZTS) and Ag-Zn-Sn-S (AZTS) nanocrystals (NCs) by means of “green” chemistry in aqueous solution and their detailed characterization by Raman spectroscopy and several complementary techniques are reported. Through a systematic variation of the nominal composition and quantification of the constituent elements in CAZTS and AZTS NCs by X-ray photoemission spectroscopy (XPS), we identified the vibrational Raman and IR fingerprints of both the main AZTS phase and secondary phases of Ag-Zn-S and Ag-Sn-S compounds. The formation of the secondary phases of Ag-S and Ag-Zn-S cannot be avoided entirely for this type of synthesis. The Ag-Zn-S phase, having its bandgap in near infrared range, is the reason for the non-monotonous dependence of the absorption edge of CAZTS NCs on the Ag content, with a trend to redshift even below the bandgaps of bulk AZTS and CZTS. The work function, electron affinity, and ionization potential of the AZTS NCs are derived using photoelectron spectroscopy measurements.     

Nanozymes with reductase-like activities: antioxidant properties and electrochemical behavior

Nanozymes (NZs) as stable cost-effective mimics of natural enzymes may be promising catalysts in food and environmental biotechnology, biosensors, alternative energy and medicine. The majority of known NZs are mimetics of oxidoreductases, although there are only limited data regarding mimetics of reductases. In the present research, a number of metal-based NZs were synthesized via chemical methods and screened for their antioxidant ability in solution. The most effective reductase-like Zn/Cd/Cu NZ was characterized in detail. Its antioxidant properties in comparison with several food products and Trolox, as well as substrate specificity, size and composition were studied. Zn/Cd/Cu NZ was shown to mimic preferentially selenite reductase. The amperometric sensor was constructed possessing a high sensitivity (1700 A M⁻¹ m⁻²) and a broad linear range (16–1000 μM) for selenite ions. The possibility to apply the fabricated sensor for selenite determination in commercial mineral water has been demonstrated.

Novel Zn/Cd/Cu^bd nanozymes possesses the ability to mimic coenzyme-dependent selenite reductase. A new amperometric biosensor for determination of selenite was constructed.     

基于心磁信号的电流密度分析方法研究

电流密度向量分析是心磁图仪临床应用中的关键诊断技术,其重构与分类效果将直接影响心脏疾病筛查的准确度。研究一种电流密度分析方法,包括电流密度重构逆向算法,并提出一种电流密度自动分类新算法。将该电流密度分析方法应用于27例健康志愿者和75例心肌缺血患者的临床验证:首先,使用四通道心磁图仪SQUID传感器采集36个测量点位心磁信号源数据,采用标准Ⅱ导联心电数据同步化心磁信号源数据;其次,应用基于傅里叶变换的逆向求解算法,重构每例受试者电流密度分布,自动计算3项电流密度分类参数CDI、IPCD、E_RT,并通过多元线性回归模型确定自动分类算法中健康组和心肌缺血组的线性判别函数;最后,借助基于KL熵值计算和线性判别函数的自动分类新算法,对重构后的电流密度进行自动分类。结果表明:健康组与心肌缺血组间3项分类参数CDI、IPCD、E_RT显著性差异分别为2.0×10^-11、2.7×10^-5和3.0×10^-4;CDI、IPCD、E_RT诊断心肌缺血的敏感性分别为73%、81%和60%,特异性分别为100%、65%和73%;自动分类结果的敏感性、真阳性率、特异性、假阳性率和真阴性率分别为89.33%、100%、100%、0%和76.47%。实验说明,所述电流密度分析方法可靠、准确度高,可用于临床心肌缺血诊断。