Synthesis, Structure and Luminescence Properties of Mn-doped MgAl2O4 Red-Emitting Phosphors with Varying Sintering Temperature.

Oxide matrix red-emitting phosphors are deemed as excellent color converters for white light emitting diodes (WLEDs) and laser diodes (LDs). Manganese-doped MgAl2O4 powder was synthesized by a solid-state reaction method at different sintering temperatures. Microstructure shows that grain size is mainly in the range of 0.2-5 µm, and grain agglomeration occurs with increased sintering temperature. XPS analysis indicates that the doped Mn ion exhibits a valence state of + 4 within the MgAl2O4 matrix. The diffraction peak of the phosphors is shifted by the sintering temperature, which affects lattice constant. Upon excitation by 300 nm ultraviolet light, the samples emit asymmetric broadband red light within the range of 620-720 nm, attributed to Mn4+ ion's transition from 2Eg to 4A2g states. With the increasing temperature, the main emission peak shifts from 677 nm to 650 nm, ascribed to the change in energy level (2Eg) resulting from the reduction of Al2O3 phase. Crystal field theory confirmed that Mn4+ ions are within a strong crystal field environment created by MgAl2O4 matrix. By affecting particle size and crystallinity, the sintering temperature influences the fluorescence lifetime of the Mn4+ ion. Notably, these red-emitting phosphors exhibits remarkable thermal stability as their emission intensity remains approximately at 58% of initial intensity even at elevated temperature (435 K). Consequently, Mn4+: MgAl2O4 red-emitting phosphors with high thermal stability render them promising candidates for WLED applications.

Polarizability inversion suspension for nonlinear optical limiting with a low limiting threshold.

We propose what we believe to be a novel nonlinear optical limiting (NOL) method with a low limiting threshold based on a light intensity-controlled polarizability inversion suspension (PIS). This suspension has negative polarizability under weak light, allowing stable propagation of weak light with a low loss. Nevertheless, the suspension reverses into positive polarizability due to the optical Kerr effect under strong light, resulting in enhanced scattering that rapidly attenuates the intense light. In a proof-of-concept experiment, PS (polystyrene)-CS2-CCl4 suspension is used as the example suspension. We experimentally verify the NOL performance of several samples. Among them, 4 g/L PS-CS2-CCl4 suspension with a volume ratio of 0.15 has the best optical limiting effect, with a high limiting capacity coefficient of 0.48 and a very low limiting threshold of 14.80 kW/cm2, which is an order magnitude lower than that of most common NOL materials. Therefore, the proposed method provides a new promising approach to achieve NOL of continuous wave laser with a low limiting threshold.

Strong nonlinear optical limiting of resin composed by carbon nanotubes.

The development of solid-state nonlinear optical limiting (NOL) materials is crucial for advancing the practicality in the field of optical limiting. In this paper, we innovatively prepare a new solid NOL material which is spiral carbon nanotubes doped epoxy resin (SCNTs-doped ER, SER) with a simple physical mixing method, and achieve an excellent nonlinear optical limiting performance. We experimentally measured optical limiting of SER with different SCNTs concentrations (0.14, 0.28, and 0.43 mg/mL) and obtained the nonlinear absorption coefficient, nonlinear refractive index, and third-order nonlinear susceptibility at the wavelength 1064 nm. Z-scan experiment results show that the SER exhibits a large nonlinear absorption coefficient (5.07 ± 0.38) × 10-9 m/W. We also measure the transmittance of the SER to evaluate its nonlinear optical limiting performance. For the SER with 0.43 mg/mL concentration, the linear transmittance and minimum transmittance with NOL effects at 1064 nm are 54.8% and 26.2%, respectively. In addition, the SER also has prominent features such as a high damage threshold and easy fabrication, indicating that the SER is a promising solid material for nonlinear optical limiting.

Full-range depth-encoded swept source polarization sensitive optical coherence tomography.

To realize the high sensitivity polarization sensitive optical coherence tomography (PS-OCT) imaging, a fiber-based full-range depth-encoded swept source PS-OCT (SS-PS-OCT) method is proposed. The two OCT images corresponding to the orthogonal polarized input light are located on the high sensitivity imaging region of the opposite sides relative to the zero optical path difference position. The full-range OCT images can be obtained by implementing the spatial phase modulation in the reference arm. The detection sensitivity of the system was measured experimentally to be 67 dB when the imaging depth approaching to 2 mm. The imaging of the biological tissue verifies that the proposed full-range depth-encoded SS-PS-OCT system has the higher detection sensitivity compared with the conventional depth encoded SS-PS-OCT system. Finally, we demonstrated the full-range high sensitivity phase retardation image of the bovine tendon and skin of human fingertip. The fiber-based full-range depth-encoded SS-PS-OCT method can realize the high sensitivity birefringence imaging in the medical diagnosis scenes with the requirements for long imaging range and high detection sensitivity.

Molecular basis underlying default mode network functional abnormalities in postpartum depression with and without anxiety.

Although Postpartum depression (PPD) and PPD with anxiety (PPD-A) have been well characterized as functional disruptions within or between multiple brain systems, however, how to quantitatively delineate brain functional system irregularity and the molecular basis of functional abnormalities in PPD and PPD-A remains unclear. Here, brain sample entropy (SampEn), resting-state functional connectivity (RSFC), transcriptomic and neurotransmitter density data were used to investigate brain functional system irregularity, functional connectivity abnormalities and associated molecular basis for PPD and PPD-A. PPD-A exhibited higher SampEn in medial prefrontal cortex (MPFC) and posterior cingulate cortex (PPC) than healthy postnatal women (HPW) and PPD while PPD showed lower SampEn in PPC compared to HPW and PPD-A. The functional connectivity analysis with MPFC and PPC as seed areas revealed decreased functional couplings between PCC and paracentral lobule and between MPFC and angular gyrus in PPD compared to both PPD-A and HPW. Moreover, abnormal SampEn and functional connectivity were associated with estrogenic level and clinical symptoms load. Importantly, spatial association analyses between functional changes and transcriptome and neurotransmitter density maps revealed that these functional changes were primarily associated with synaptic signaling, neuron projection, neurotransmitter level regulation, amino acid metabolism, cyclic adenosine monophosphate (cAMP) signaling pathways, and neurotransmitters of 5-hydroxytryptamine (5-HT), norepinephrine, glutamate, dopamine and so on. These results reveal abnormal brain entropy and functional connectivities primarily in default mode network (DMN) and link these changes to transcriptome and neurotransmitters to establish the molecular basis for PPD and PPD-A for the first time. Our findings highlight the important role of DMN in neuropathology of PPD and PPD-A.

Frequency selection rule for the HDHF Lissajous scanning imaging with a low-voltage one axis actuated PZT scanner based on an asymmetric fiber cantilever.

Lissajous micro scanners are very attractive in compact laser scanning applications for biomedical endoscopic imaging, such as confocal microscopy, endomicroscopy or optical coherence tomography. The scanning frequencies have a very important effect on the quality of the resulting Lissajous scanning imaging. In this paper, we propose a frequency selection rule for high definition and high frame-rate (HDHF) Lissajous scanning imaging, by deriving the relationship among the scanning field of view (FOV), actuation frequencies and pixel size based on the characteristics of the scanning trajectory. The minimum sampling rate based on the proposed frequency selection rule is further discussed. We report a lead zirconate titanate piezoelectric ceramic (PZT) based Lissajous fiber scanner to achieve HDHF Lissajous scanning imaging. Based on the frequency selection rule, different frequency combinations are calculated, under which the Lissajous fiber scanner can work at the frame rate (FR) of 10 Hz, 20 Hz, 40 Hz and 52 Hz. The trajectory evolution of the Lissajous scanning at the frame rate of 10 Hz has been obtained to verify the applicability of the proposed rule. The measured resolution of the scanner is 50.8 lp/mm at the unit optical magnification, and the measured FOV at the FR of 10 Hz and 40 Hz are 1.620 mm ×1.095 mm and 0.405 mm ×0.27 mm, respectively. HDHF Lissajous scanning images of the customized spatial varying binary pattern are obtained and reconstructed at the FR of 10 Hz and 40 Hz, demonstrating the practicability of the frequency selection rule.

Nonlinear optical limiting effect of porous graphene dispersions at 1064 nm.

This work presents a new, to the best of our knowledge, porous graphene dispersion in ethanol that can achieve a good nonlinear optical limiting (NOL) effect at the wavelength of 1064 nm. Using the Z-scan system, the nonlinear absorption coefficient of the porous graphene dispersion with a concentration of 0.01 mg/mL was measured as 9.69×10-9 c m/W. The NOL of the porous graphene dispersions in ethanol under three different concentrations (0.01, 0.02, and 0.03 mg/mL) were measured. Among them, the 1-cm-thick porous graphene dispersion with a concentration of 0.01 mg/mL has the best optical limiting effect, in which the linear transmittance is 76.7%, and the lowest transmittance is 24.9%. By using the pump-probe technique, we detected the formation and annihilation times of the scatter when the suspension interacts with the pump light. The analysis shows that the NOL mechanisms of the novel porous graphene dispersion are mainly nonlinear scattering and nonlinear absorption.

Local polarization properties extraction using single incident state, single-mode-fiber-based spectral domain polarization-sensitive optical coherence tomography.

We showed the local polarization properties extraction method for the single incident state, all-single-mode-fiber-based spectral domain polarization-sensitive optical coherence tomography (SD-PS-OCT) system that uses the single linear-in-wavenumber spectral camera. Polarization controllers are used in the single-mode-fiber-based SD-PS-OCT system to provide a compact structure with polarization state stability. The local polarization properties of the birefringent sample are extracted from the cumulative polarization properties iteratively. The reconstructed polarization images demonstrate the local polarization properties extraction ability of the system.

Third-order optical nonlinearity measurements and optical limiting experiment in Tm: YAG crystal.

In this paper, we investigate the third-order nonlinearities and optical limiting effect of Tm: YAG crystal at a wavelength of 1064 nm. We experimentally measure different energy densities (6.4, 12.8, and 19.2J/cm2) and obtain the nonlinear absorption coefficient, nonlinear refractive index, and third-order nonlinear susceptibility of Tm: YAG crystal. Z-scan results show that Tm: YAG crystal exhibits a large nonlinear absorption coefficient (3.34×10-9m/W) at the wavelength of 1064 nm. We also measure the transmittance of Tm: YAG crystals of three different lengths (7, 15, and 20 mm) to evaluate its nonlinear optical limiting performance. For the 20 mm Tm: YAG crystal, the maximum transmittance without optical limiting effect and minimum transmittance with nonlinear optical limiting effect at a 1064 wavelength nm are 84.2% and 47.8%, respectively, which indicates that Tm: YAG crystal may be a solid material for nonlinear optical limiting at 1064 nm.

Reporting Excellent Transverse Piezoelectric and Electro-Optic Effects in Transparent Rhombohedral PMN-PT Single Crystal by Engineered Domains.

Transparent ferroelectric crystals with high piezoelectricity are challenging to build because of their complex structure and disordered domains in rhombohedral relaxor ferroelectrics. There are eight domains along the <111> direction, which cause light scattering. In this study, perfect transparency is achieved along the [110] and [001] directions in [110]-poled rhombohedral 0.72Pb(Mg1/3 Nb2/3 )O3 -0.28PbTiO3 (PMN-PT) crystals, which have a high d31 value of 1700 pC N-1 and a high electro-optic coefficient γ33 of 320 pm V-1 . This implies that the [110]-oriented rhombohedral PMN-0.28PT crystal can realize the mode of transverse modulation, whereas the [001]-oriented PMN-0.28PT crystal is more suitable for the longitudinal mode. Through piezoresponse force microscopy (PFM), it is confirmed that the [110]-poled rhombohedral PMN-PT crystals form 71° layered domains, which are similar to the 109° layered domains of the [001]-oriented transparent crystal. Combined with PFM and birefringence microscopy, the degradation of domains and thickness dependence of piezoelectricity provide clear evidence for the relationship between the engineered domain structures and piezoelectric properties, which should be considered in the design of piezoelectric or electro-optic devices with excellent performance. This work enriches the research on ferroelectric domain engineering for excellent transparency and high piezoelectricity to provide new ideas for photoacoustic devices.

Miniaturized precalibration-based Lissajous scanning fiber probe for high speed endoscopic optical coherence tomography.

We present a miniaturized precalibration-based forward-viewing Lissajous scanning fiber probe for high speed endoscopic optical coherence tomography (OCT). The probe is based on an asymmetric fiber cantilever driven by the piezoelectric bender to realize two-dimensional (2D) Lissajous scanning. The stability and repeatability of the Lissajous scanning trajectory of the probe is tested by a position sensitive detector (PSD)-based position calibration setup. The two orthogonal resonant frequencies of the cantilever are measured to be 167.2 and 121 Hz. A 25 µm focal spot is formed at the working distance of 5 mm by the graded-index (GRIN) lens, and the field of view of the imaging probe is around ${1.5}\;{\rm mm} \times {1.5}\;{\rm mm}$1.5mm×1.5mm. The probe is fully packaged in a hypodermic tube for endoscopic imaging. The total rigid length and outer diameter are 35 mm and 3.5 mm, respectively. The probe is incorporated in a 50 KHz swept source OCT system with the axial resolution of 14 µm, and its imaging performance is validated by the 2D en face and 3D volumetric OCT imaging of the phantom and the biological tissue.

Giant tunability of upconversion photoluminescence in Er3+-doped (K, Na)NbO3 single crystals.

Perovskite oxides with luminescent ions hold great promise in optoelectronic devices because of their outstanding thermal stabilities and electro-optic performance. As one typical perovskite upconversion (UC) host material, lead-free potassium sodium niobate ((K, Na)NbO3/(KxNa1-x)NbO3 or KNN) has attracted much attention in recent years. In the present work, a novel routine was developed to tune the upconversion photoluminescence (UC PL) performance by controlling the oxygen vacancy concentration in the KNN matrix, based on the 0.1% Er3+-doped KNN (Er-KNN) single crystals grown for the first time. UC PL properties, conductivity and defect chemistry of the single crystals were systematically investigated. The UC PL intensity of the as-grown Er-KNN material could be enhanced by 20 times after oxygen atmosphere annealing at 800 °C and fully quenched after vacuum annealing. What's more, by annealing under an oxygen atmosphere and vacuum, the conductivity of the Er-KNN sample was successfully tuned for more than 8 orders of magnitude. The super-wide range tunability of UC PL performance and conductivity could be explained by oxygen vacancies which gave rise to Nb5+-Nb4+ valence alternation. Because of the modulated photoluminescence properties and conductivity, our grown Er-KNN single crystals have great potential for use in multifunctional devices.

[Expression of glycoprotein non-metastatic melanoma protein B in clear-cell renal cell carcinoma and clinical implication thereof].

OBJECTIVE: To elucidate the glycoprotein non-metastatic melanoma protein B(Gpnmb) expression in clear-cell renal cell carcinoma (ccRCC) and to determine its potential prognostic relevance. METHODS: A total of 12 pairs of ccRCC tissue specimens were collected from patients undergoing surgery in our hospital from March 2009 to March 2012. Gpnmb expression were determined by immunohistochemistry and correlated with clinical variables. Survival analysis was carried out for another 43 evaluable patients. RESULTS: The expression level of Gpnmb was significantly higher in metastatic ccRCCs than that in matched primary samples ((6.36±4.01) vs (3.14±2.38) scores, P=0.036). The high expression of Gpnmb was not affected by age, gender, clinical stage and pathological grade (all P>0.05). Kaplan-Meier analysis disclosed significant differences in overall survival for patients with higher and lower average Gpnmb expression levels (P=0.020). Cox regression analysis revealed that a high Gpnmb protein expression level in the tumor cell could be identified as an independent poor prognostic marker of overall survival in ccRCC patients (P=0.049). CONCLUSION: Over expression of Gpnmb in tumour cell predicts a poor prognosis of patients with ccRCC.

[Diagnosis and treatment of hydrocephalus-accompanied renal calculi complicated with renal tumor: 5 case reports].

OBJECTIVE: To investigate the diagnosis and treatment of renal pelvic tumor combined with renal urinary calculi and hydronephrosis. METHODS: Five patients with renal pelvic tumor who underwent relief of the upper urinary obstruction were reviewed. RESULTS: One of the cases lost the opportunity of surgical therapy when pelvic tumor was detected at the advanced stage, and the other 4 cases had received surgery and were followed up. CONCLUSION: As pelvic tumor progresses rapidly after the renal blood flow is improved, and renal urinary calculi with hydronephrosis relieved; the patients with renal pelvic tumor need early diagnosis, aggressive treatment and close follow-up.

Linear electro-optic properties of orthorhombic PZN-8%PT single crystal.

The optical transmittance spectra of relaxor ferroelectric 0.92Pb(Zn(1/3)Nb(2/3))O(3)-0.08PbTiO(3) (PZN-8%PT) single crystals poled along different directions have been systematically studied at room temperature. After being poled along the [011] direction, the transmittance of induced orthorhombic PZN-8%PT single crystal is more than 50% from 0.5 to 5.7 µm, which is much higher than that poled along the [001] and [111] directions. The refractive indices and linear electro-optic properties of the orthorhombic PZN-8%PT single crystal were characterized at a wavelength of 632.8 nm. Large electro-optic responses were observed, (γ33) = 220 pm/V, (γ13) = 62 pm/V, and (γ23) = 23 pm/V. Thus, orthorhombic PZN-8%PT single crystal is a promising material for high-performance electro-optic devices.

Full tensorial elastic, piezoelectric, and dielectric properties characterization of [011]-poled PZN-9%PT single crystal.

Transverse piezoelectric property of 0.91Pb(Zn(1/3)Nb(2/3))O(3)-0.09PbTiO(3) (PZN-9%PT) single crystal poled along [011] direction under different fields have been investigated, the poling field giving the best property was between 350 and 650 V/mm at room temperature. Full tensorial elastic, dielectric, and piezoelectric properties of PZN-9%PT single crystal poled along the [011] direction under 500 V/mm have been determined by resonance and ultrasonic methods. It was found that the electromechanical coupling coefficients k(32) and k(33) can reach 0.90 and 0.89 and the piezoelectric coefficients d(32) and d(15) are -1705 and 2012 pC/N, respectively. This complete set of physical properties can provide convenience for piezoelectric device fabrication and domain engineering studies.

[Comparison and clinical significance between geometrical characteristics of tibial plateau between Uighur nationality and Han people].

OBJECTIVE: To compare the difference and clinical significance of geometrical characteristics of tibial plateau between Uighur nationality and Han people by computed tomography scan and three-dimensional reconstruction. METHODS: A total of 49 inpatients and outpatients were randomly selected (normal knee without any tibial involvement) and volunteers of Han people and 45 ones of the Uighur nationality at our hospital and cooperative hospitals. Then the subjects were divided into groups according to gender. The following linear geometric parameters of tibial plateau were measured: width of tibial plateau (WTP), width of medial tibial plateau (WMTP), sagittal length of medial tibial plateau (SLMTP), width of lateral tibial plateau (WLTP) and sagittal length of lateral tibial plateau (SLLTP). RESULTS: (1) Males were greater than females in linear parameters in the same group (P < 0.01); (2) the groups of Uighur nationality were greater than groups of Han people in linear parameters in the same gender (P < 0.05); (3) the gaps between WMTP and WLTP, SLMTP and SLLTP of Uighur nationality were all more approximate than those of Han people (P < 0.05). CONCLUSION: The geometrical characteristics of tibial plateau have some visible discrepancy between Uighur nationality and Chinese Han people. The prosthetic design concept and technology of total knee replacement targeting the Uighur nationality should take into consideration the discrepancy.