Red-enhanced white light-emitting diodes using external AlGaInP epilayers with various aperture ratios

A novel hybrid white light-emitting diode (LED) is proposed to enhance the red color and stability of the chromaticity under various operating currents using an AlGaInP photon-recycling (PR) epilayer. A blue/yellow white InGaN LED sample is covered with an external patterned AlGaInP epilayer. Under an optimum aperture ratio of 30%, the luminous efficiency of the PR-LED lamp can achieve a color coordinate of (x=0.340, y=0.295). When the injection current increases from 50 to 350 mA, the color temperature decreases from 4030 to 3700 K and the color rendering index increases from 81 to 86. These could be due to the fact that the AlGaInP epilayer was not attached onto the LED chip, alleviating the thermal effect on the color coordinate. The present white PR-LED samples have high potential for portable liquid-crystal-display backlight applications.     

Dual immobilization and magnetic manipulation of magnetic nanoparticles

By suitably bio-functionalizing the surfaces, magnetic nanoparticles are able to bind specific biomolecules, and may serve as vectors for delivering bio-entities to target tissues. In this work, the synthesis of bio-functionalized magnetic nanoparticles with two kinds of bio-probes is developed. Here, the stem cell is selected as a to-be-delivered bio-entity and infarcted myocardium is the target issue. Thus, cluster designation-34 (CD-34) on stem cell and creatine kinase-MB (CK-MB) (or troponin I) on infarcted myocardium are the specific biomolecules to be bound with bio-functionalized magnetic nanoparticles. In addition to demonstrating the co-coating of two kinds of bio-probes on a magnetic nanoparticle, the feasibility of manipulation on bio-functionalized magnetic nanoparticles by external magnetic fields is investigated.     

Linear Boltzmann equation as the weak coupling limit of a random Schrödinger equation

We study the time evolution of a quantum particle in a Gaussian random environment. We show that in the weak coupling limit the Wigner distribution of the wave function converges to a solution of a linear Boltzmann equation globally in time. The Boltzmann collision kernel is given by the Born approximation of the quantum differential scattering cross section. © 2000 John Wiley & Sons, Inc.     

Eval membranes for blood dialysis

Both dry- and wet-process were employed for preparing membrane of ethylene-vinylalcohol copolymer (EVAL) for blood dialysis. Asymmetric and symmetric, dense or porous membranes were prepared by the dry-process. The relationship between the structure of membranes and the experimental variables is explained by using a solubility curve model. This model predicts the membrane structure successfully under various conditions, including the change of temperature of the environment, the solvent system and the temperature of polymer solution. For wet-processes, the casting solutions were coagulated in a precipitation bath (water). Three different structures were obtained: finger type, sponge type and particle-bonded type. The cloud point experiment and the polymer segment motion help to understand and control the membrane structure. Some properties of the EVAL membrane for blood dialysis are shown. It is comparable with or better than the commercialized one. This study may prove useful in determing the controlling parameters for the preparation of membranes from other polymers.     

Role of p-d hybridization in the Tc-variation of Y(Rh1−xRux)4B4 superconductors

Auger and photoemission studies for Y(Rh_1?xRu_x)₄B₄ superconductors elucidate the mechanism for the abrupt drop in T_c near x=0.5. The B $\text{p}$-states admix more strongly with Ru than Rh $\text{d}$-states, thereby yielding low-T_c values for Ru-rich compounds due to broadening of the $\text{d}$-band feutures. These effects underlie a previous suggestion that the preservation of Rh₄ tetrahedral units is essential for high-T_c values in ternary boride compounds.     

A theoretical analysis of epitaxial growth of CuInS2 by chemical vapour deposition

Summary A theoretical analysis has been carried out to investigate the kinetics involved in the CVD growth of CuInS₂. A stagnant-layer model is assumed for the numerical, simulation. Computational results for the growth rate as a function of the substrate temperature, mean, gas velocity and partial pressures in the reaction tube are obtained. This analysis indicates that the substrate temperature plays a dominant role in the growth rate, which is consistent with our experimental data. Paper presented at the ?V International Conference on Ternary and Multinary Compounds?, held in Cagliari, September 14–16, 1982.     

Direct determination of lead at sub-ppb levels in secondary coolants of pressurized water reactor by electrothermal atomic absorption spectrometry with multiple injections

The method of incorporating in-situ pre-concentration technique via multiple injections followed by electrothermal atomic absorption spectrometry (ETAAS) is described for the direct determination of lead at sub-ppb levels in secondary coolants of pressurized water reactor (PWR). Prior to ETAAS measurement, water samples were concentrated by means of multiple injections (9×90 ml) and evaporation in a pyrocoated graphite tube. Optimization of the in-situ pre-concentration via multiple injections with ETAAS analysis was investigated. The feasibility of the proposed method was tested for direct determination of lead in secondary coolants of pressurized water reactor. A SRM 1643c certified reference water sample has been used for quality control. The result are in good agreement with the certified value. By the use of 0.81 ml sample volume 0.012 ppb detection limit was obtained.     

Pregnane‐Based Steroids from a Formosan Gorgonian Subergorgia Mollis

A new steroid, 11α, 15α‐diacetoxy‐17α‐pregna‐4,20‐dien‐3‐one ( 1 ), and a known one, 17α‐pregna‐4,20‐dien‐3‐one ( 2 ), have been isolated from a Formosan gorgonian Subergorgia mollis. The structures of both compounds were determined on the basis of extensive NMR experiments, including HMQC, HMBC, ¹H‐¹H COSY and NOESY. Metabolite 2 has not been isolated from a natural source before. The detailed ¹H and ¹³C NMR spectral data of 2 are reported for the first time.     

Novel Anti‐Inflammatory Constituents of Artocarpus rigida

A novel phenolic compound containing an oxepine ring, artocarpol I ( 1 ), and a new biphenylpropanoid, artocarpol J ( 2 ), were isolated from the root bark of Artocarpus rigida. The structures, including relative configurations, were elucidated by spectroscopic data. Compound 1 and artocarpol J peracetate ( 3 ) strongly inhibited in a concentration‐dependent manner the formyl‐Met‐Leu‐Phe (fMLP)/cytochalasin B (CB)‐stimulated superoxide anion formation in neutrophils with IC₅₀ values of 17.1±0.40 and 20.5±2.60 μM , respectively. Biogenetically, all the novel phenolic compounds isolated from this plant seem to be derived from stilbene.     

Monosubstituted Trinuclear and Tetranuclear VIB Metal Carbonyl Complexes: Syntheses of [{M(CO)5}3(Pf-Pf-Pf)] [Pf-Pf-Pf = PhP(CH2CH2PPh2)2] and [{M(CO)5}4(P-Pf3)] [P-Pf3 = P(CH2CH2PPh2)3] (M = Cr,Mo) and Crystal Structures of the Latter Three

The triligate trimetallic complexes, [{M(CO)₅}₃(Pf-Pf-Pf)] and tetraligate tetrametallic complexes, [{M(CO)₅}₄(P-Pf₃)] (M = Cr and Mo), were prepared from [M(CO) ₆] and the corresponding ligands in MeCN/CH₂Cl₂ promoted by Me₃NO at 0 °C. Crystals of trimer lb are monoclinic, space group P 2₁/n, with a = 13.407(3), b = 15.002(5), c = 26.52(1) Å, β = 90.65(2)°, Z = 4, and R = 0.060 for 2760 observed reflections. Crystals of tetramer 2a are monoclinic, space group P 2₁/c, with a – 14.183(8), b = 29.880(4), c = 16.103(2) Å, β = 94.98(3)°, Z = 4, and R = 0.039 for 5014 observed reflections. Crystals of 2b are monoclinic, space group C 2/c, with a = 42.120(8), b = 13.679(1), c = 23.486(2) Å, β = 92.14(1)°, Z = 8, and R = 0.032 for 6897 observed reflections. Each phosphorus atom of the ligands is coordinated to the M(CO)₅ moiety in each title compounds. The geometry of the four metals is a distorted tetrahedron for the tetramers.