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A theoretical study has been performed on effect of polarization state of incident plane wave on performance of photonic nanojet (PNJ) generated by a sphere or an ellipsoid or an elliptical cylinder scatterer, among which the sphere has a higher while the ellipsoid and elliptical cylinder have a relatively low geometric symmetry. The study shows that the polarization state of incident wave affects mainly full width at half maximum of the PNJ in case of the sphere scatterer, whilst influences mainly the focal length in case that the scatterer is an ellipsoid or elliptical cylinder. Further study focuses on the effect on the focal length of the PNJ generated by either an ellipsoid or an elliptical cylinder scatterer, and the influences of type, geometric size and orientation of scatterer on the effect. The results show that the effect prefers to take place for a scatterer with a lower symmetry, and the type, geometric size and orientation of scatterer all can influence the effect. There exists a maximum effect at a certain symmetry and the maximum effect depends on the type, geometric size and orientation of scatterer. In the case of the elliptical cylinder, the focal length of PNJ generated can increase by as much as two times as the polarization state is changed. [ABSTRACT FROM AUTHOR]

Neuroscientists have emphasized visceral influences on consciousness and attention, but the potential neurophysiological pathways remain under exploration. Here, we found two neurophysiological pathways of heart-brain interaction based on the relationship between oxygen-transport by red blood cells (RBCs) and consciousness/attention. To this end, we collected a dataset based on the routine physical examination, the breaking continuous flash suppression (b-CFS) paradigm, and an attention network test (ANT) in 140 immigrants under the hypoxic Tibetan environment. We combined electroencephalography and multilevel mediation analysis to investigate the relationship between RBC properties and consciousness/attention. The results showed that RBC function, via two independent neurophysiological pathways, not only triggered interoceptive re-representations in the insula and awareness connected to orienting attention but also induced an immune response corresponding to consciousness and executive control. Importantly, consciousness played a fundamental role in executive function which might be associated with the level of perceived stress. These results indicated the important role of oxygen-transport in heart-brain interactions, in which the related stress response affected consciousness and executive control. The findings provide new insights into the neurophysiological schema of heart-brain interactions. [ABSTRACT FROM AUTHOR]

The mutual influence of co-diffused Ti and Sc in LiNbO single-crystal was studied. Sc/Ti co-doped LN plates were prepared by annealing (at 1060 °C in wet O) Z-cut congruent LiNbO substrates coated with stacked ScO and Ti films, which have different thicknesses and coating sequences. After the annealing, the refractive index and composition at the undoped and Sc-only doped surface parts were characterized by prism coupling technique. The Sc and Ti profiles were analyzed by secondary ion mass spectrometry. The results show that the Sc-doping has little contribution to the LiNbO refractive index. LiO out-diffusion is not measurable. In the only diffusion case, the Sc diffuses five times slower than the Ti. In the Sc/Ti co-diffusion case, the Ti assists and controls the Sc diffusion. The Sc diffusivity increases linearly with the initial Ti-metal thickness. In contrast, the Sc affects the Ti diffusion little. Neither the ScO film thickness nor the coating sequence influences the diffusivity of the two ions. The co-diffusion features are explained. A model for the co-diffusion system is suggested and verified experimentally. The Ti:Sc:LiNbO planar and strip waveguide are optically characterized. The results show that the Sc presence does not affect the waveguide characteristics and the waveguide is optical-damage-resistant. [ABSTRACT FROM AUTHOR]

Intense broad absorption bands centered around 1.7, 2.5, 3.1, and 3.7 eV take place in Er3+-diffused layer formed near MgO (5 mol%)-doped LiNbO3 crystal surface by in-diffusion of Er metal under Li-poor atmosphere. These bands are tentatively attributed to the defect absorption of small polarons, bipolarons, F-centers, and Q-polarons created due to Er3+ in-diffusion and Li2O loss from the crystal. It is interesting that the number, type, area, and peaking position of the bands can be controlled by the diffusion temperature and further oxidation treatment. Such material is a promising medium for data storage based upon two-color holography. [ABSTRACT FROM PUBLISHER]

Locally Er3+-doped noncongruent, Li-deficient Ti:Er:LiNbO3 strip waveguide was fabricated with a technological process in sequence of preparation of Li-deficient LiNbO3 substrate using Li-poor vapor transport equilibration (VTE), Er3+, and Ti4+ diffusion in wet O2. The Li2O content change was evaluated from the measured birefringence. The Ti4+ and Er3+ profile characteristics in the waveguide were studied by secondary ion mass spectrometry. The results show that the VTE and subsequent Er3+ diffusion procedures resulted in totally ∼0.8 mol% Li2O content reduction. The Ti4+ profile follows a sum of two error functions in the width direction and a Gaussian function in the depth direction of waveguide. The Er3+ profile follows also a Gaussian function. At 1130 °C, the Ti4+ surface/depth diffusivity and surface concentration are 8.5 ± 1.3/1.98 ± 0.06 μm2/h and ∼7 mol%, respectively, and the Er3+ diffusivity and surface concentration are (12.8 ± 0.3) × 10−2 μm2/h and ∼0.6 mol%, respectively. [ABSTRACT FROM PUBLISHER]

Near-stoichiometric (NS) (Mg:)Er:LiNbO3 crystals were grown from melts containing 0.0/0.5, 0.5/0.5, and 1.0/0.5 mol%/mol% MgO/Er2O3. Crystal composition and optical properties studies show that the Li2O contents in these crystals increase all by ∼1 mol% relative to the congruent point. The 1.0 mol% MgO-doped NS crystal is just near optical damage threshold and withstands a 488 nm light intensity >0.74 MW/cm2 without optical damage. Unpolarized absorption spectra of these NS crystals were measured, and the Er3+ absorption cross-section spectra were determined. The Er3+ spectroscopic properties were studied by Judd–Ofelt theory. The results show that as the crystal composition approaches the stoichiometry, the Er3+ spectroscopic properties change definitely. The Er3+ ion in the NS crystal has smaller absorption cross section and hence weaker oscillator strength, lower emission rate, and longer radiative lifetime. Nevertheless, the radiative quantum efficiency is retained. In addition, the MgO codoping has less effect on the Er3+ spectroscopic properties. [ABSTRACT FROM AUTHOR]

Congruent Er:Mg:LiNbO3 crystals were grown by the Czochralski method from the melts containing fixed 0.5 mol% Er2O3 while varied MgO content ranged from 0.0 to 8.0 mol%. The Mg and Er contents in the crystals were determined by neutron activation analysis. In the presence of Er codopant, the Mg threshold concentration with respect to optical damage is determined from the measured OH absorption spectra. The results show that the Er codopant has less effect on both the Mg threshold concentration and Mg segregation coefficient, which is within 1.13–1.23 as the Mg concentration is below the threshold while within 0.88–0.98 when above the threshold, consistent with the only MgO doping case. On the other hand, the practical Er concentration in the crystal is closely related to the Mg content and shows definite Mg threshold effect. Below the threshold, the Er concentration decreases linearly with the increased Mg concentration in the crystal; above the threshold, the decrease is more remarkable and follows another linear function. The Mg concentration effect on the Er segregation coefficient is discussed from the viewpoint of the Mg doping effect on the solubility of Er ions in the crystal. [ABSTRACT FROM AUTHOR]

At 1100 °C, the diffusion properties of Ti4+ into congruent LiNbO3 crystals codoped with 0.5 mol% Er2O3 and different MgO concentrations of 0.5, 1.0, and 1.5 mol% have been studied by secondary ion mass spectrometry (SIMS). Three Y-cut and three Z-cut plates with different Mg doping levels were coated with a 60-nm-thick Ti film at first and then annealed at 1100 °C for 28 h in a wet O2 atmosphere. SIMS was used to analyze depth profile characteristics of diffused Ti ions and the constituent elements of the substrate as well. The results show that the diffusion reservoir was exhausted and the Ti metal film was completely diffused. All measured Ti profiles follow a Gaussian function. No Mg out-diffusion accompanied the Ti in-diffusion procedure for all crystals studied. The 1/e diffusion depth is similar to 8.3/10.2, 7.4/8.7, and 6.6/8.2 ± 0.2/0.2 μm/μm for the Y/Z-cut crystal with the Mg doping level of 0.5, 1.0, and 1.5 mol%, respectively, yielding a Ti4+ diffusivity of 0.62/0.93, 0.49/0.67, and 0.39/0.60 ± 0.03/0.03 (μm2/h)/(μm2/h), respectively. The diffusion shows definite anisotropy and a considerable MgO doping level effect. Under the same Mg doping level, the diffusion in a Z-cut crystal is faster. The diffusivity decreases with the increase of the Mg doping level. This effect is qualitatively explained from the viewpoint of the Mg doping effect on concentration of the intrinsic defects in LiNbO3 crystal. [ABSTRACT FROM AUTHOR]

Production of an extracellular lipase from Serratia marcescens ECU1010, which is an industrially important biocatalyst for the stereospecific synthesis of Diltiazem precusor, was carefully optimized in both shake flasks and a fermenter, using Tween-80 as the enzyme inducer. Dextrin and beef extract combined with ammonium sulfate were indicated to be the best carbon and nitrogen sources, respectively. With the increase of Tween-80 from 0 to 10 g l−1, the lipase production was greatly enhanced from merely 250 U l−1 to a maximum of 3,340 U l−1, giving the highest lipase yield of ca 640 U g−1 dry cell mass (DCW), although the maximum biomass (6.0 g DCW l−1) was achieved at 15 g l−1 of Tween-80. When the medium loading in shake flasks was reduced from 20 to 10% (v / v), the lipase production was significantly enhanced. The increase in shaking speed also resulted in an improvement of the lipase production, although the cell growth was slightly repressed, suggesting that the increase of dissolved oxygen (DO) concentration contributed to the enhancements of lipase yield. When the lipase fermentation was carried out in a 5-l fermenter, the lipase production reached a new maximum of 11,060 U l−1 by simply raising the aeration rate from 0.5 to 1.0 vvm, while keeping the dissolved oxygen above 20% saturation via intermittent adjustment of the agitation speed (≥400 rpm), in the presence of a relatively low concentration (2 g l−1) of Tween-80 to prevent a potential foaming problem, which is easy to occur in the intensively aerated fermenter. [ABSTRACT FROM AUTHOR]

We have studied thermal effect on filtering feature of electro-optic long period grating (LPG) in Ti-diffused LiNbO3 waveguide, and observed the phenomenon of thermally induced multi-wavelength filtering. At room temperature (20.8 °C), a rejection band due to LPG effect is observed at 1450 nm wavelength regime for a driving voltage of 115 V. As the temperature is increased, the band weakens gradually, and is no longer discernible at 27 °C. Meanwhile, three new dips with similar contrasts and wavelength intervals are resolved at shorter wavelengths 1190, 1265 and 1339 nm. Their contrasts increase with a rise in temperature and have a value of 20 dB at available temperature of 44.5 °C. The positions of these dips change little with the temperature, but red-shift with the increase of driving voltage. These dips are associated with thermally induced multi-mode interference. [ABSTRACT FROM AUTHOR]

Diffusion-doping is an effective, practical method to improve material properties and widen material application. Here, we demonstrate a new physical phenomenon: diffusion control of an ion by another in LiNbO3 and LiTaO3 crystals. We exemplify Ti4+/Xn+ (Xn+ = Sc3+, Zr4+, Er3+) co-diffusion in the widely studied LiNbO3 and LiTaO3 crystals. Some Ti4+/Xn+-co-doped LiNbO3 and LiTaO3 plates were prepared by co-diffusion of stacked Ti-metal and Er-metal (Sc2O3 or ZrO2) films coated onto LiNbO3 or LiTaO3 substrates. The Ti4+/Xn+-co-diffusion characteristics were studied by secondary ion mass spectrometry. In the Xn+-only diffusion case, the Xn+ diffuses considerably slower than the Ti4+. In the Ti4+/Xn+ co-diffusion case, the faster Ti4+ controls the diffusion of the slower Xn+. The Xn+ diffusivity increases linearly with the initial Ti-metal thickness and the increase depends on the Xn+ species. The phenomenon is ascribed to the generation of additional defects induced by the diffusion of faster Ti4+ ions, which favors and assists the subsequent diffusion of slower Xn+ ion. For the diffusion system studied here, it can be utilized to substantially shorten device fabrication period, improve device performance and produce new materials. [ABSTRACT FROM AUTHOR]