Xixia Zhang

Bulk crystal growth and characterization of semi-organic nonlinear optical crystal tri-diethylammonium hexachlorobismuthate (TDCB)

Bulk semi-organic nonlinear optical (NLO) single-crystals of tri-diethylammonium hexachlorobismuthate (TDCB) with sizes up to 22 × 21 × 15 mm3 have been grown from concentrated hydrochloric acid by the slow-cooling method. TDCB crystallizes in the trigonal system, the R3c space group, with a = 14.699(4) A and c = 19.102(5) A. Its morphology has been indexed to reveal the major facets of the crystal to be {110} and {012}. Transmittance spectra of TDCB show an optical transmission in the entire visible region with the cutoff wavelength at 365 nm. The powder second harmonic generation (SHG) measured by using the Kurtz and Perry technique indicates that TDCB is a phase-matchable NLO material with a SHG efficiency of 1.8 times that of KH2PO4 (KDP). Its specific heat and thermal expansion were investigated as a function of temperature, and the relationship between the structure and the thermal properties has been discussed. Furthermore, laser-induced damage threshold measurements show a threshold up to 2.32 GW cm−2. All the results demonstrate that the semi-organic crystal TDCB is promising in NLO applications.

Flux method growth of bulk MoS2 single crystals and their application as a saturable absorber

Molybdenum disulfide (MoS2) has attracted a great deal of attention because of its outstanding physical, chemical and optoelectronic properties. The method used to prepare large sized MoS2 crystals of very high quality is still an important issue for determining the feasibility of its application. Herein, we propose a novel Sn flux method to grow single crystal MoS2, and bulk MoS2 single crystals with a size of 3 mm × 5 mm were successfully obtained by using a cooling rate of 2–4 °C h−1. The growth mechanism of the MoS2 crystal in Sn flux was investigated in detail using optical microscopy and atomic force microscopy (AFM). The obvious screw dislocation steps that are revealed suggest that the growth of MoS2 is controlled by a screw-dislocation-driven (SDD) spiral growth mechanism. The flux-grown MoS2 crystals were exfoliated to produce high-quality large-scale films using the liquid-phase exfoliation method. Using ultrathin MoS2 films as a saturable absorber, a passively Q-switched laser at a wavelength of 1.06 μm was constructed and operated, with a narrow pulse width of 326 ns.

Modified Bridgman growth and characterization of a novel mid-infrared transparent optical crystal: LiGa3Te5

A large single LiGa3Te5 (LGT) crystal was grown with size up to O16 mm × 50 mm for the first time using a modified vertical Bridgman–Stockbarger method. LGT crystallizes in the non-centrosymmetric system, space group R32, with a = b = 14.343(7) A, c = 17.617 A, Z = 12, and V = 3139 A3. A detailed description of the polyhedral connections in the LGT structure is presented. The X-ray rocking curve, specific heat and thermal conductivity are also investigated. The room-temperature transmission of the as-grown LGT without any coating is above the 40% level from 3.5 to 18 μm. The cut-off edges at short and long wavelength are 0.9 and 25 μm, respectively. Owing to its wide transparency range, LGT is a promising candidate for MIR and far-infrared NLO applications, and even for THz transmission and generation.

Controllable seeded flux growth and optoelectronic properties of bulk o-SiP crystals

Two-dimensional (2D) materials have recently attracted great interest due to their promising optoelectronic applications. Orthorhombic SiP (o-SiP) is a 2D layered crystal and may have a significant impact on optoelectronic technologies. Large-sized bulk o-SiP single crystals have been successfully grown by a seeded flux method. The size and morphology of o-SiP crystals can be controlled by changing the growth conditions. The carrier mobility and band gap of o-SiP were characterized in detail. The photoresponse properties of o-SiP were investigated and a relatively fast response has been demonstrated. The experimental results indicate that o-SiP may be an excellent candidate for applications in electronics and optoelectronics.

Flux growth and characterization of an FeSi4P4 single crystal

Herein, a single crystal of FeSi4P4 (FSP) with dimensions up to 8 × 7 × 3 mm3 was successfully grown using a seeded flux growth method. Single crystal X-ray diffraction results revealed that the FSP crystal crystallized in the chiral space group P1 (no. 1). High-resolution X-ray diffraction presents a full-width at half-maximum (FWHM) of 36′′ and 46′′ for the (100) and (001) FSP crystals, respectively, which indicates that FSP crystals have high crystalline quality. FSP is thermally stable up to 1157.1 °C and has a high thermal conductivity of 35 W (m K)−1 at room temperature. The magnetic analysis shows that the FSP crystal is paramagnetic in the range from 5 to 300 K. The Hall effect measurement suggests that the FSP crystal is a promising p-type semiconductor at room temperature.

TEMPOROMANDIBULAR JOINT DISC REPOSITIONING BY MODIFIED ANCHORAGE SURGERY

The appropriate position and morphologic preservation of the disc are critical to prevent excess remodeling and degenerative changes within the temporomandibular joint. The paper reviews the history of surgical approaches to disc displacement and presents a modified technique of temporomandibular joint disc reposition developed by the authors. Seven key points are highlighted that are essential for the success of the proposed arthroscopic intervention. The anterior release should be complete, with avoidance of any damage to the masseteric nerve and vessels. Expansion of the upper joint space to ensure appropriate placement of the incision should be performed with the straight ramus retractor used to distract the mandible and injecting saline, which helps prevent cutting of the disc or cartilage when entering the fossa. The disc should be repositioned without any tension. Two mattress sutures (one medial and one lateral) should be placed at the border of the disc and the posterior band. The disc is fixed with one bone anchor which is sufficient for its further stability. The position of the disc should be overcorrected to avoid relapse. Autogenous fat grafting in the anterior release region is vital to lessen scarring and thus to improve long term outcomes. All steps of the proposed technique are discussed with comparison with previous approaches. Factors influencing a relapse and measures to prevent it are reviewed in detail.

Excision of a selectable marker in transgenic lily (Sorbonne) using the Cre/loxP DNA excision system

Li, S. H., Du, Y.-P., Wu, Z. H.-Y., Huang, C.-L., Zhang, X.-H., Wang, Z. H.-X. and Jia, G.-X. 2013. Excision of a selectable marker in transgenic lily (Sorbonne) using the Cre/loxP DNA excision system. Can. J. Plant Sci. 93: 903-912. To generate transgenic lily plants with no selectable marker and improved tolerance to abiotic stress, two vectors were co-transformed into the Lilium oriental hybrid Sorbonne by particle bombardment. The pKSB vector included the Cre/loxp-mediated site-specific cDNA excision system under control of the inducible promoter rd29A, and the pBPC-P5CS-F129A vector carried the P5CS gene, which we hypothesized would improve resistance to drought and salt stresses in transgenic lily plantlets. The presence of the two genes was simultaneously detected by PCR and Southern blotting in two resistant plantlets. The co-transformation rate was 0.16%. Subsequently, inducer expression was tested under varying conditions to optimize the deletion of marker gene. Results from molecular detection assays revealed that maintaining bases of bulblet scales at 4°C for 12 h resulted in an increase in the excision rate, reaching 60%. Expression of P5CS improved resistance to salt stress in transgenic lily plantlets. These results demonstrated the feasibility of using the Cre/loxP-based marker elimination system to generate marker-free transgenic plantlets with improved stress tolerance.