Engineering Refractive Index Contrast in Thin Film Barium Titanate-on-Insulator.

Barium titanate-on-insulator has demonstrated excellent vertical optical confinement, low loss, and strong electro-optic properties. To fabricate a waveguide-based device, a region of higher refractive index must be created to confine a propagating mode, one way of which is through dry etching to form a ridge. However, despite recent progress achieved in etching barium titanate and similar materials, the sidewall and surface roughness resulting from the physical etching typically used limit the achievable ridge depth. This motivates the exploration of etch-free methods to achieve the required index contrast. Here, we introduce three etch-free methods to create a refractive index contrast in barium titanate-on-insulator, including a metal diffusion method, proton beam irradiation method, and crystallinity control method. Notably, molybdenum-diffused barium titanate leads to a large index change of up to 0.17. The methods provided in this work can be further developed to fabricate various on-chip barium titanate optical waveguide-based devices.

Design and fabrication of high-performance multimode interferometer in lithium niobate thin film.

We propose and demonstrate a type of high-performance transverse magnetic (TM) multimode interferometer (MMI) in Z-cut thin film lithium niobate (TFLN). Both 1 × 2 and 4 × 4 MMI designs are demonstrated. Simulation results show that the insertion losses (ILs) are nominally about 0.157 and 0.297 dB for the 1 × 2 and 4 × 4 MMI, respectively, with wide fabrication tolerances. Based on the designed structure, the MMIs are fabricated using an argon based induced coupled plasma (ICP) etching method in Z-cut TFLN. The measured ILs are 0.268 and 0.63 dB for these two kinds of devices. The presented TM mode MMI featuring compact size and low loss can be used for both multifunctional devices and on-chip integrated circuits on a Z-cut TFLN platform.

Spatially tunable photonic bandgap of wide spectral range and lasing emission based on a blue phase wedge cell.

This study demonstrates for the first time a continuously tunable photonic bandgap (PBG) of wide spectral range based on a blue phase (BP) wedge cell. A continuously shifting PBG of the BP wedge cell occurs due to the thickness gradient of the wedge cell at a fixed temperature. The wedge cell provides a gradient of boundary force on the LCs and thus forms a distribution of BP crystal structure with a gradient lattice. Additionally, a spatially tunable lasing emission based on a dye-doped BP (DDBP) wedge cell is also demonstrated. The tunable band of the PBG and lasing emission is about 130 nm and 70 nm, respectively, which tuning spectral ranges are significantly wider than those of CLC and DDCLC wedge cells, respectively. Such a BP device has a significant potential in applications of tunable photonic devices and displays.

Development and validation of a novel approach based on ultrasonic-assisted enzymatic extraction and RP-UHPLC for simultaneous determination of astaxanthin isomers and alpha-tocopherol in Haematococcuspluvialis derived supplements.

A rapid, effective andgreenmethod was developed for simultaneous determination of total (free and esterified) astaxanthin (AX) isomers (all-E, 9Z and 13Z) and alpha-tocopherol(AT) in Haematococcuspluvialis derived supplements. The new method employed a highly efficient ultrasonic-assisted enzymatic extraction (UAEE) techniqueto perform deesterificationwith Cholesterol esterase from Pseudomonas fluorescenspermitting the concurrent detection. The subsequent RP-UHPLC method for separating and measuring was performed on a simple C18 column within 10.5 min by using methanol and ammonium acetate as mobile phase with a gradient elution. The proposed method was validated according to international guidelines and itproved to be highly accurate and robust. The optimized UHPLC method allowed easy transfer to HPLC, and allowed rapid analysis of active ingredients profiling in H. derived supplements.To our knowledge, this is the first quantification approach describing the rapid simultaneous analysis of the functional lipophilic substances including AX isomers in H. derived supplements using UAEE technique combined with RP-UHPLC.Moreover, this holistic approachcan be used to identify whether AX products are of natural origin or chemical synthesis, and may find more applications in new forms of H. derived productswith complexbiological matrix for more research on the bioavailability of AXisomersfrom natural source.

Identification and quantification of tetrodotoxin in the marine gastropod Nassarius by LC-MS.

Tetrodotoxin (TTX) has been usually analyzed in marine and other sources by HPLC separation, followed by alkaline treatment and fluorescence assay. However, the applications of such methods were limited because of their tedious extraction and derivation procedures. A simpler, rapid LC-MS method, using selected ion-monitoring, has now been developed, and used to identify and quantitate TTX in a marine gastropod of the genus Nassarius, collected from Fijian province of China. The toxin was confirmed comparable to authentic TTX by MS and MSn. In addition, a moderate amount of TTX was detected in the Nassarius by this novel approach, suggesting that Nassarius would be a potential food poison source.

Glasgow Coma Scale and hematoma volume as criteria for treatment of putaminal and thalamic intracerebral hemorrhage.

BACKGROUND: The decision to administer conservative or surgical treatment for putaminal and thalamic ICH is still a controversial issue. This study was undertaken to examine the decision-making criteria for these 2 treatments. METHODS: In a retrospective study, case records of 400 patients with spontaneous putaminal and thalamic hemorrhage who underwent conservative treatment (n = 201) and surgical treatment (n = 199) over the past 5 years were examined. Conservative treatment included hypertonic solution treatment and hypertension control. Surgical treatments included endoscopic surgery, craniotomy, and stereotactic aspiration. Preoperative GCS score and ICH volume were the major evaluating factors, and comparison of the 30-day mortality rate and 6-month BI score was used for outcome evaluation. RESULTS: In patients with a GCS score of 13 to 15, there was no difference in mortality between conservative and surgical treatments. At a GCS score of 9 to 12 and ICH volume of less than 30 mL, the mortality rate with surgical treatment (10.5%) was lower than that with conservative treatment (20.0%, P < .05). At a GCS score of 3 to 8 and ICH volume of at least 30 mL, surgical treatment was for life saving. Mortality rates were lower for conservative treatment than for surgical treatment when the GCS score was 3 to 12 and ICH volume less than 30 mL. Endoscopic surgery had a better functional outcome compared with craniotomy and stereotactic aspiration when the GCS score was at least 9 (P < .001 and P < .02, respectively). Those in conservative treatment received a better BI score than those in surgical treatment did when the ICH volume was less than 40 mL (P < .001). CONCLUSIONS: Intracerebral hemorrhage volume is probably more important than GCS score in determining treatment. Our nonrandomized data could be interpreted to show that conservative treatment is suggested at GCS score of at least 13 or when ICH volume is less than 30 mL, regardless of GCS score. Surgical treatment could be recommended at GCS score of less than 12 with ICH volume of at least 30 mL for life saving. Endoscopic surgery may improve the functional outcomes because it is less invasive and effectively removes the ICH at GCS score of at least 9.

Efficient All-Vacuum Deposited Perovskite Solar Cells by Controlling Reagent Partial Pressure in High Vacuum.

All-vacuum-deposited perovskite solar cells produced by controlling reagent partial pressure in high vacuum with newly developed multi-layer electron and hole transporting structures show outstanding power conversion efficiency of 17.6% and smooth, pinhole-free, micrometer-sized perovskite crystal grains.

Cofacial Versus Coplanar Arrangement in Centrosymmetric Packing Dimers of Dipolar Small Molecules: Structural Effects on the Crystallization Behaviors and Optoelectronic Characteristics.

Two D-π-A-A molecules (MIDTP and TIDTP) composed of an electron-rich ditolylamino group (D) and an electron-deficient 5-dicyanovinylenylpyrimidine (A-A) fragment bridged together with indeno[1,2-b]thiophene (IDT) were synthesized. These molecules provide an opportunity to examine in-depth the impact of side-chain variations (methyl vs p-tolyl) on the crystallization behaviors, solid-state morphology, physical properties, and optoelectronic characteristics relevant for practical applications. X-ray analyses on single-crystal structures indicate that methyl-substituted MIDTP forms "coplanar antiparallel dimers" via C-H···S interactions and organizes into an ordered slip-staircase arrays. In contrast, p-tolyl-bearing TIDTP shows "cofacial centrosymmetric dimers" via π-π interactions and packs into a less-ordered layered structures. The X-ray diffraction analyses upon thermal treatment are consistent with a superior crystallinity of MIDTP, as compared to that of TIDTP. This difference indicates a greater propensity to organization by introduction of the smaller methyl group versus the bulkier p-tolyl group. The increased propensity for order by MIDTP facilitates the crystallization of MIDTP in both solution-processed and vacuum-deposited thin films. MIDTP forms solution-processed single-crystal arrays that deliver OFET hole mobility of 6.56 × 10(-4) cm(2) V(-1) s(-1), whereas TIDTP only forms amorhpous films that gave lower hole mobility of 1.34 × 10(-5) cm(2) V(-1) s(-1). MIDTP and TIDTP were utilized to serve as donors together with C70 as acceptor in the fabrication of small-molecule organic solar cells (SMOSCs) with planar heterojunction (PHJ) or planar-mixed heterojunction (PMHJ) device architectures. OPV devices based on higher crystalline MIDTP delivered power conversion efficiencies (PCEs) of 2.5% and 4.3% for PHJ and PMHJ device, respectively, which are higher than those of TIDTP-based cells. The improved PCEs of MIDTP-based devices are attributed to better hole-transport character.