Biomedical subjects

Minhua Jiang

Publications and source records attributed to Minhua Jiang.

15 recordsLinked to original sources

PubMed2006

High-power laser performance of a-cut and c-cut Yb:LuVO4 crystals.

We report high-power laser operation that was achieved with a-cut and c-cut Yb:LuVO(4) crystals. Up to 8.3 W of pi-polarized output power was generated from an a-cut, 2 mm uncoated crystal with an optical conversion efficiency of 59%. The highest slope efficiency was 80%. Laser oscillation obtained with c-cut crystal was also linearly polarized, with two orthogonal polarization components along [110] and [(-)110] directions. The highest output power achieved was 4.5 W, with an optical conversion efficiency of 33% and a slope efficiency of 40%.

Journal Article↗

PubMed2006

Low-temperature growth of uniform ZnO particles with controllable ellipsoidal morphologies and characteristic luminescence patterns.

Uniform ellipsoidal ZnO particles have been synthesized in an aqueous solution in the presence of triethonalamine (TEA) mediated by sonication at the temperature below 80 degrees C. Scanning electron microscopy observations reveal that the ellipsoidal particles are highly uniform with a hexagonal cross-section. The morphologies of the ZnO particles can be systematically controlled from elongated rugby ball-like ellipsoidal to half-ellipsoidal by increasing the TEA concentration. Spatial resolved cathodoluminescence measurements at room temperature show that the ellipsoidal ZnO particles are intrinsically encoded with barcode-like ultraviolet luminescence patterns, which are of either a wide stripe or a narrow stripe perpendicular to the length at the core of the particles depending on the growth temperature. Moreover, the luminescence spectra of the ellipsoidal particles can be tuned by heat treatments at elevated temperatures, while maintaining the luminescence patterns. We believe that the well-defined uniform ellipsoidal ZnO particles embedded with unique luminescence characteristics hold great potential for use in bioengineering and photonics, such as biological labeling and optical probes.

Adsorption↗

PubMed2006

Characteristics of a continuous-wave Yb:GdVO4 laser end pumped by a high-power diode.

An efficient and compact diode-pumped continuous-wave Yb:GdVO4 laser is demonstrated, generating an output power of 4.0 W with an optical conversion efficiency of 61% and a slope efficiency as high as 78%. With increasing pump power the polarization of the laser output changes from sigma to pi, while in a certain intermediate power range the two polarization states coexist with different emission wavelengths.

Journal Article↗

PubMed2006

Study of electronic and spectroscopic properties on a newly synthesized red fluorescent material.

The ground state (S(0)) and the lowest singlet excited state (S(1)) of a newly synthesized red fluorescent material, 2-[3-(2-{4-[(2-Hydroxy-ethyl)-methyl-amino]-phenyl}-vinyl)-5,5-dimethyl-cyclohex-2-enylidene]-malononitrile (A31), are investigated. The S(0) and S(1) geometries are optimized at the ab initio Hartree-Fock and the singles configuration interaction (CIS) levels of theory, respectively. The CIS and semiempirical Zerner's Intermediate Neglect of Differential Overlap (ZINDO) methods provide the results for the absorption (S(0)-->S(1)) and emission (S(1)-->S(0)) transition energies. The Stokes shifts calculated at the CIS and ZINDO levels of theory are obtained. The absorption spectra in various solvents are calculated using the time-dependent density-functional theory method in combination with the polarized continuum model, which are in very good agreement with our experimental measurements. The solvent effects are discussed.

Journal Article↗

PubMed2006

Precise fabrication of point defects in self-assembled three-dimensional macroporous photonic crystals.

We demonstrate a new and simple method of precisely fabricating defects in three-dimensional (3D) CdS macroporous photonic crystals (PCs) with a variable pressure scanning electron microscope. Well-defined point defects, not only vacancies but also an impurity (a reduced-size sphere), were directly fabricated by electron-beam irradiation under a gas atmosphere. This provides a convenient and straightforward method of introducing various designed defects into 3D PCs for photonic-band-gap-based applications.

Cadmium Compounds↗

PubMed2005

Continuous-wave laser performance of Nd:LuVO4 crystal operating at 1.34 microm.

A laser-diode-array end-pumped Nd:LuVO4 crystal continuous-wave (cw) laser operating at 1.34 microm has been demonstrated. The maximum cw output power of 1.85 W was obtained at the incident pump power of 17 W for a c-cut 0.5 at. % Nd-doped LuVO4 crystal sample, giving the corresponding optical conversion efficiency of 10.88% and a slope efficiency of 13.5%. Laser experiments of Nd3+ concentration of 0.5 and 0.9 at. % a-cut crystal LuVO4 samples were also investigated; due to the strong excited-state absorption of Nd:LuVO4 at 1.34 microm, the output power was limited.

Journal Article↗

PubMed2005

Continuous-wave laser operation of Yb:LuVO4.

We report on the room-temperature spectroscopic properties and continuous-wave laser operation of a new Yb:LuVO4 crystal. The peak absorption cross section for the pi-polarization is 8.42 x 10(-20) cm2 at 985 nm, and the stimulated emission cross section at 1020 nm is 1.03 x 10(-20) cm2. An output power of 0.36 W at 1041 nm was obtained with a slope efficiency of 47% by use of Ti:sapphire laser pumping. With diode pumping the output power reached 1.05 W at the highest available incident pump power of 6.8 W.

Journal Article↗

PubMed2005

A facile sulfur vapor assisted reaction method to grow boron nitride nanorings at relative low temperature.

Boron nitride (BN) nanorings were synthesized using a sulfur vapor assisted solid-state method at 600 degrees C. The rings had typical diameters of 100-300 nm, and the shells were 5-20 nm thick and about 50 nm wide. On the basis of the characterization of X-ray powder diffraction pattern (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transformation infrared spectroscopy (FTIR) measurement, the as-prepared product was pure-phase hexagonal BN. High-resolution transmission electron microscopy (HRTEM) images proved that the nanorings were formed through the coiling of the (002) planes of hexagonal BN. A possible growth process for BN nanorings is suggested.

Journal Article↗

PubMed2004

Continuous-wave and pulsed laser performance of Nd:LuVO4 crystal.

Received August 11, 2003 We report continuous-wave and actively Q-switched laser performance achieved with Nd:LuVO4 crystal for the 4F(3/2) --> 4I(1/2) transition (corresponding wavelength of 1065.8 nm) under high-power diode pumping. Continuous-wave output power of 12.55 W is obtained with an optical conversion efficiency of 50.2%. In actively Q-switched operation the average output power reaches 5.42 W at a pulse repetition frequency of 40 kHz with 18 W of pump power incident upon the crystal, yielding an optical conversion efficiency of 30.1%. The pulse energy and peak power reach 138 microJ and 16.2 kW, respectively, at a pulse repetition frequency of 25 kHz under a pump power of 14.2 W; the pulse duration is 8.5 ns.

Journal Article↗

PubMed2003

Formation of a novel 1D supramolecule [HgCl2(ptz)]2.HgCl2 (ptz = phenothiazine): a new precursor to submicrometer Hg2Cl2 rods.

A novel supramolecule [HgCl(2)(ptz)](2).HgCl(2) (ptz = phenothiazine) with uncoordinated inorganic salt HgCl(2) presented in a 1D chain was first prepared and then successfully applied as a new precursor in the preparation of submicrometer Hg(2)Cl(2) rods. Single crystal X-ray analysis showed that the 1D chain structure is stabilized by hydrogen bonds between adjacent chains and the coordination mode of the ligand phenothiazine is unusual with large steric inhibition other than the chain directions. The results revealed that the particular chain structure plays a significant role in the formation of the Hg(2)Cl(2) rods.

Journal Article↗

PubMed2003

The regulatory effect of memantine on expression and synthesis of heat shock protein 70 gene in neonatal rat models with cerebral hypoxic ischemia.

OBJECTIVE: To evaluate the neuroprotective effect of memantine, a non-competitive antagonist at the N-methyl-D-aspartate receptor, against hypoxic ischemia (HI) by exploring its regulation on the expression and synthesis of heat shock protein 70 (HSP70) gene in neonatal rat models with cerebral HI. METHODS: Memantine was intraperitoneally injected at a dose of 20 mg/kg in neonatal rat models either before (PRE group) or after (POST group) induction of HI. The expression and synthesis of the HSP70 gene and its corresponding product were determined by rapid competitive PCR and immunohistochemistry, respectively. RESULTS: There was an increase in the expression of HSP70 mRNA two hours after induction of HI, which reached its peak at 48 hours, then decreased gradually. The same expression occurred at relatively low levels in the control group. Also, HSP70 synthesis was detected as early as 2h after HI, reached its peak between 48 and 72 hours, then declined over time. After memantine administration, the expression of the gene and its synthesis of the corresponding product decreased significantly during the time intervals 24 - 72 h for the gene and 48 - 72 h for the product compared to the HI group. CONCLUSION: It was shown that HI is very sensitive to the expression of the HSP70 gene and synthesis of its corresponding product, which could be regulated by memantine. The latter may have the ability to reduce brain damage; thus decreased HSP70 mRNA expression could be a marker for HI. It is suggested that memantine can be a promising agent for neuroprotection against HI, although an overall and objective assessment of memantine is required to see if it can be used on neonates clinically later on.

Animals↗

PubMed2002

Studies on the two-photon pumped upconverted fluorescence and superradiance of a new organic dye material in solutions.

The linear and nonlinear optical properties of a new organic dye, trans-4-[p-(N-ethyl-N-ethylamino)-styryl]-N-methyl-pyridinium tris(thiocyanato) cadmates (II), are reported in this paper. When pumped with a picosecond laser at the wavelength range of 850-1200 nm, intense upconversion fluorescence can be obtained. The upconversion efficiencies at different pump energies were measured when pumped with a 1064-nm laser beam from a mode-locked Nd:YAG laser. The highest upconversion efficiencies were measured to be 5.8% and 7.6% in dimethyl formamide (DMF) and methanol. The lifetime of the dye in DMF was measured to be 75 ps. The strongest nonlinear absorption was at the wavelength of 940 nm, and the highest upconversion efficiency was at the wavelength of 1030 nm. The difference of the two wavelengths was caused by excited state absorption in the dye at wavelengths shorter than 1000 nm. The dye solution in DMF and methanol show a clear optical power limiting effect.

Journal Article↗

PubMed2002

2'-Hydroxy-4"-dimethylaminochalcone.

The title compound, 3-[4-(dimethylamino)phenyl]-1-(2-hydroxyphenyl)prop-2-en-1-one, C(17)H(17)NO(2), is a chalcone derivative substituted by 2'-hydroxyl and 4"-dimethylamino groups. The crystal structure indicates that the aniline and hydroxyphenyl groups are nearly coplanar, with a dihedral angle of 10.32 (16) degrees between their phenyl rings. The molecular planarity of this substituted chalcone is strongly affected by the 2'-hydroxyl group.

Journal Article↗

PubMed2002

Mild benzene-thermal route to GaP nanorods and nanospheres.

GaP nanorods and nanospheres were synthesized from a mild benzene-thermal route at 240 and 300 degrees C, respectively, using Na, P, and GaCl(3) as the starting materials. The structure of the products was identified as zinc blende phase by X-ray powder diffraction (XRD). Transmission electron microscopy (TEM) images showed that, when the reaction temperature was 240 degrees C, the products were nanorods with widths of 20-40 nm and lengths of 200-500 nm and nanospheres with diameters of 20-40 nm. However, when the reaction temperature was increased to 300 degrees C, the products were only nanospheres, and the diameters increased to 40-60 nm. The reaction proceeded through a metallic gallium intermediate, and a solution-liquid-solid (SLS) mechanism was proposed for the one-dimensional growth. The products were also investigated by UV-vis absorption and X-ray photoelectron spectroscopy.

Journal Article↗

PubMed2002

Upconversion fluorescence and optical power limiting effects based on the two- and three-photon absorption process of a new organic dye BPAS.

A new organic dye, trans-4, 4'-bis(pyrrolidingl) stilbene (BPAS), with large two-photon absorption (TPA) and three-photon absorption (3PA) has been synthesized. The molecular TPA cross section sigma2' at 550-670 nm and the 3PA cross section sigma3' at 720-1000 nm have been measured. The biggest sigma2' and sigma3' was 5.77 x 10(-47) cm4s/photon and 27 x 10(-75) cm6 s2 at 600 and 980 nm, respectively. In the experiment process we found that the strongest TPA wavelength is not at two times of the strongest linear absorption wavelength, but there is some blue shift. The 3PA-induced optical power-limiting properties have also been illustrated at 980 nm.

Absorption↗