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We analyzed and compared the optical, spectral, and thermal characteristics of InGaN/GaN near-ultraviolet (NUV) flip-chip (FC) light-emitting diodes (LEDs) packaged on the board with dielectric/metal layers (DMB package), board with ceramic/metal layers (CMB package), and board with ceramic/metal layers and thermal tape (CMBT package) in the injection current range of 0-800 mA at 298 and 358 K. For the DMB packaged LED, the relatively high junction temperature was observed due to the inefficient heat dissipation, leading to the more optical output power drop and spectral shift. For the CMBT packaged device, it further dissipated heat at high currents where the performance of CMB packaged device was degraded. In comparison with the experimental results, the theoretically calculated temperature and stress distributions of the NUV FC LEDs with the DMB and CMB packages were also investigated by finite element method-based simulations. [ABSTRACT FROM AUTHOR]

We investigated the device characteristics of GaN-based blue vertical light-emitting diodes (VLEDs) with two different package structures ( i.e. , lead frame with metal/plastic body (MPLF package) and lead frame with metal body (MLF package)) under various measurement conditions. In comparison with the MPLF packaged VLEDs, the MLF packaged VLEDs exhibited relatively lower junction temperature and thermal resistance values due to the better heat dissipation capability, leading to further improved optical, spectral, and thermal device characteristics. Thermal simulations of the VLEDs with two different packages were performed using three-dimensional steady-state device models to theoretically calculate their thermal and mechanical behaviours. The maximum temperatures, internal temperature distributions, and thermomechanical stresses were analysed by a finite element method. [ABSTRACT FROM AUTHOR]

The device performance improvement of ridge waveguide (RWG) laser diodes (LDs), operating at a wavelength (λ) of ∼960 nm, with a metal-dielectric high-reflection (HR) mirror consisting of Au/Ti–SiO 2 layers on the back facet was demonstrated. To determine the optimum thickness of each layer, optical reflection calculations were performed using a rigorous coupled-wave analysis method, which leads to the resultant Au (80 nm)/Ti (5 nm)–SiO 2 (164 nm) layers. The layers exhibited a broad high reflection band of >91% over a wavelength range of 920–1000 nm, indicating the reflectivity of ∼91.2% at λ ∼ 960 nm. For 2 mm-cavity RWG LDs with the Au/Ti–SiO 2 HR mirror, an enhanced maximum output power (P max ) of 499.3 mW at an injection current of 3000 mA and a decreased threshold current (I th ) of 516 mA (i.e., P max = 259.4 mW and I th = 650 mA for the uncoated LDs) were obtained, showing an increased slope efficiency percentage of 82%. The external differential quantum efficiency was also increased from ∼17.1 to ∼31.1%. Also, the full widths at half maximum values of beam divergences of the device were 38° (vertical direction) and 4° (horizontal direction). [ABSTRACT FROM AUTHOR]

The temperature-dependent device characteristics of InGaN/GaN near-ultraviolet light-emitting diodes, operating at λ ∼380 nm, with a chip size of 0.5 × 1 mm2 were reported. Their optical and spectral properties were measured and analyzed at different injection current levels and heatsink temperatures. The device performance showed the optical output power of 92.8 mW, forward voltage of 4.30 V, and emission peak wavelength of 380 nm at 350 mA and 298 K. The junction temperature ( Tj) was experimentally estimated via the forward voltage method, leading to a thermal resistance of ∼10.03 K W−1. For comparison with the simulated Tj, the three-dimensional steady-state heat transfer simulation based on the finite element method was also carried out. [ABSTRACT FROM AUTHOR]

Highly-transparent coverglasses coated with broadband and omnidirectional antireflective (AR) moth-eye nanopatterned ultra-violet (UV) curable polymer, i.e., Norland Optical Adhesive (NOA) 63, films are reported. The moth-eye nanopatterns on the NOA63 polymer films/glasses are transferred from the silicon molds with conical nanogratings (NGs) using poly-dimethylsiloxane stamps by a soft imprint lithography technique. For the NOA63 NGs/glasses, surface wetting behaviors, UV radiation/thermal effects, and optical properties, together with theoretical analyses using rigorous coupled-wave analysis calculations, are investigated. For a period of 380 nm, the NOA63 NGs/glass exhibits a hydrophobic surface with a water contact angle of ~112°. Furthermore, it increases the transmittance of the bare glass over a wide range of wavelengths and incident light angles, showing the higher solar weighted transmittance ( T SW ) of ~93.2% at an incident angle ( θ i ) of 0° and the larger average T SW value of ~83.6% at θ i =10–70° than those (i.e., T SW ~90.1% at θ i =0° and average T SW value of ~81.5% at θ i =10–70°) of the bare glass in the wavelength range of 350–1800 nm. In addition, it shows a relatively good stability under intense UV radiation and high temperature. By employing the 380 nm-period NG patterned NOA63 films into an AR coating of coverglasses in encapsulated III-V GaInP/GaInAs/Ge triple-junction solar photovoltaic (PV) sub-receiver modules, an enhanced power conversion efficiency (PCE) of 31.33% is obtained mainly due to an increased short-circuit current density ( J SC ) of 14.68 mA/cm 2 compared to reference PV modules with the bare coverglass (i.e., PCE=30.12% and J SC =14.07 mA/cm 2 ) at θ i =0°. For incident angle-dependent PV module characteristics, it also has more outstanding solar energy conversion properties in a wide θ i range of 10–70°. [ABSTRACT FROM AUTHOR]

Abstract: Two new flavonoids, wushanicaritin (1) and wushankaempferol (2), along with 24 known flavonoids were isolated from the whole herb of Epimedium wushanense T.S. Ying (Berberidaceae). On the basis of NMR and ESI-MS spectroscopic analysis, structures of compounds 1 and 2 were elucidated as 8-γ-hydroxy-γ,γ-dimethylpropyl-3,5,7-trihydroxy-4′- methoxyflavone and kaempferol 3-O-α-l-[2,3-di-O-β-d-(6-E-p-coumaroyl) glucopyranosyl]-rhamnopyranosyl-7-O-α-l-rhamnopyranoside, respectively. DPPH radical scavenging activity tests indicated that 1 (IC50 35.3μM) exhibited antioxidant activity comparable to Vitamin C (IC50 32.0μM), while 2 (IC50 443.7μM) showed weak activity. [Copyright &y& Elsevier]

Abstract: In this study, a systematic method was established for the global quality control of Xian-ling-gu-bao capsules (XLGB), a popular six-herb Traditional Chinese Patent Medicine (TCPM) for the treatment of osteoporosis. Both qualitative and quantitative analyses were conducted. In qualitative analysis part, a fast and sensitive method based on high-performance liquid chromatography coupled with diode-array detection and electrospray ionization tandem mass spectrometry (HPLC-DAD–MS n ) was established for rapid separation and sensitive identification. Samples were separated on a Waters Symmetry C18 column (250mm×4.6mm, 5μm) by gradient elution using acetonitrile (A) and water–formic acid (B; 0.03%, v/v) as mobile phase at a flow rate of 1.0ml/min. Based on the mass spectra, UV spectra and retention time, 47 compounds were identified or tentatively characterized, including 27 flavonols (all from Epimedii Herba, the major component herb), 4 coumarins, 3 flavonones, 1 chalcone, 3 isoflavones, 1 coumestrol, 3 triterpenoid saponins, 1 iridoid, 3 steroidal saponins, and 1 phenolic acid. Among them, 18 compounds were confirmed by comparing with reference standards. In quantitative analysis part, 10 major compounds in 18 batches of XLGB were simultaneously determined by HPLC/UV detected at 270nm. The method was validated with respect to intra- and inter-day precision, repeatability and stability, with RSD less than 1.0%, 1.5%, 2.9% and 1.8%, respectively. All the 10 analytes showed good linearity in wide linear ranges (r 2 =0.9999), and their average recoveries varied between 97.8% and 104.9%. [Copyright &y& Elsevier]

We investigated the highly-reflective and conductive indium tin oxide (ITO) single material-based distributed Bragg reflectors (DBRs), operating at a center wavelength of 565 nm, by a glancing angle deposition method. The porous ITO films were formed at an incident vapor flux angle of 80°, indicating the effective refractive index of ~ 1.258. The optical properties (e.g., reflectance and normalized stop bandwidth) were enhanced as the number of pairs was increased. The maximum reflectance and normalized stop bandwidth for the high reflectance region of > 80% were estimated to be ~ 85% and ~ 8%, respectively. Furthermore, the incident angle-dependent reflectance characteristics were also investigated in the incident angle range of 20–60° for p -, s -, and non-polarization. For comparison, the theoretical optical modeling and simulation were performed using the rigorous coupled-wave analysis method, exhibiting a similar tendency with the experimental results. The effective electrical characteristics of ITO DBRs were also obtained. [ABSTRACT FROM AUTHOR]

Background: Salinization damages the health of soil systems and reduces crop yields. Responses of microbial communities to salinized soils and their functional maintenance under high salt stress are valuable scientific problems. Meanwhile, the microbial community of the salinized soil in the plateau environment is less understood. Here, we applied metagenomics technology to reveal the structure and function of microorganisms in salinized soil of the Tibetan Plateau. Results: The diversity of composition and function of microbial community in saline soil have changed significantly. The abundances of chemoautotrophic and acidophilic bacteria comprising Rhodanobacter, Acidobacterium, Candidatus Nitrosotalea, and Candidatus Koribacter were significantly higher in saline soil. The potential degradation of organic carbon in the saline soil, as well as the production of NO and N2O via denitrification, and the production of sulfate by sulfur oxidation were significantly higher than the non-saline soil. Both types of soils were rich in genes encoding resistance to environmental stresses (i.e., cold, ultraviolet light, and hypoxia in Tibetan Plateau). The resistance of the soil microbial communities to the saline environment is based on the absorption of K+ as the main mechanism, with cross-protection proteins and absorption buffer molecules as auxiliary mechanisms in our study area. Network analysis showed that functional group comprising chemoautotrophic and acidophilic bacteria had significant positive correlations with electrical conductivity and total sulfur, and significant negative correlations with the total organic carbon, pH, and available nitrogen. The soil moisture, pH, and electrical conductivity are likely to affect the bacterial carbon, nitrogen, and sulfur cycles. Conclusions: These results indicate that the specific environment of the Tibetan Plateau and salinization jointly shape the structure and function of the soil bacterial community, and that the bacterial communities respond to complex and harsh living conditions. In addition, environmental feedback probably exacerbates greenhouse gas emissions and accelerates the reduction in the soil pH. This study will provide insights into the microbial responses to soil salinization and the potential ecological risks in the special plateau environment. [ABSTRACT FROM AUTHOR]

Abstract: Gegen-Qinlian-Wan (GQW) is a popular traditional Chinese patent medicine for the treatment of diarrhea. It is composed of four herbal medicines, Puerariae Radix, Scutellariae Radix, Coptidis Rhizoma, and Glycyrrhizae Radix. In this study, a rapid and sensitive method based on ultra high-performance liquid chromatography coupled with diode-array detection and quadrupole time-of-flight mass spectrometry (UHPLC-DAD-qTOF-MS) was established to characterize the chemical constituents and rats metabolites of GQW. Samples were separated on an Agilent Zorbax Eclipse Plus-C18 column (100mm×2.1mm, 1.8μm) by gradient elution using acetonitrile and water containing 0.1% formic acid as the mobile phase. On the basis of UV and qTOF high-accuracy mass spectral analysis, a total of 62 compounds were identified or tentatively characterized from GQW, including 42 flavonoids, 8 alkaloids, 6 triterpenoids, 3 phenylethanoid glycosides, and 3 other types. Among them, 27 compounds were confirmed by comparing with reference standards. Furthermore, metabolites in rats plasma and urine after oral administration of GQW were also analyzed. A total of 42 compounds were identified, including 29 prototypes and 13 metabolites through metabolic pathways of demethylation, methylation, hydrolysis, sulfate conjugation, and glucuronide conjugation. Glucuronidated flavonoids were the main constituents in the plasma, and were then transformed into aglycones and excreted from urine. This is the first systematic study on the chemical constituents and metabolic profiling of GQW. [Copyright &y& Elsevier]

Background: The biological production of 2,3-butanediol from xylose-rich raw materials from Klebsiella pneumoniae is a low-cost process. RpoD, an encoding gene of the sigma factor, is the key element in global transcription machinery engineering and has been successfully used to improve the fermentation with Escherichia coli. However, whether it can regulate the tolerance in K. pneumoniae remains unclear. Results: In this study, the kpC mutant strain was constructed by altering the expression quantity and genotype of the rpoD gene, and this exhibited high xylose tolerance and 2,3-butanediol production. The xylose tolerance of kpC strain was increased from 75 to 125 g/L, and the yield of 2,3-butanediol increased by 228.5% compared with the parent strain kpG, reaching 38.6 g/L at 62 h. The RNA sequencing results showed an upregulated expression level of 500 genes and downregulated expression level of 174 genes in the kpC mutant strain. The pathway analysis further showed that the differentially expressed genes were mainly related to signal transduction, membrane transport, carbohydrate metabolism, and energy metabolism. The nine most-promising genes were selected based on transcriptome sequencing, and were evaluated for their effects on xylose tolerance. The overexpression of the tktA encoding transketolase, pntA encoding NAD(P) transhydrogenase subunit alpha, and nuoF encoding NADH dehydrogenase subunit F conferred increased xylose consumption and increased 2,3-butanediol production to K. pneumoniae. Conclusions: These results suggest that the xylose tolerance and 2,3-butanediol production of K. pneumoniae can be greatly improved by the directed evolution of rpoD. By applying transcriptomic analysis, the upregulation of tktA, pntA, and nuoF that were coded are essential for the xylose consumption and 2,3-butanediol production. This study will provide reference for further research on improving the fermentation abilities by means of other organisms. [ABSTRACT FROM AUTHOR]