Effects of forest fire protection on tree phenology in a tropical deciduous dipterocarp-oak forest, Thailand. (original) (raw)
Related papers
Optical properties of high-temperature annealed Eu-implanted GaN
Optical Materials, 2006
A 10 nm thick epitaxially grown AlN cap has been used to protect the surface of a GaN epilayer both during Eu ion implantation and the subsequent high-temperature annealing. The 15 K photoluminescence (PL) intensity of the intra-4f Eu transition increases by two orders of magnitude when the annealing temperature is increased from 1000 to 1300°C. High-resolution PL spectra reveal that the emission lines due to the 5 D 0-7 F 2 transition exhibit different dependencies on the annealing temperature in the studied annealing range. PL excitation measurements demonstrate band edge absorption by the GaN host at 356 nm, together with a broad excitation band centred at 385 nm. The PL spectra of the 5 D 0-7 F 2 transition selectively excited by above band-gap absorption and by this broad excitation band are noticeably different. The first peak at 620.8 nm is suppressed when exciting below the GaN band gap. This demonstrates differing energy transfer processes for the different Eu luminescent peaks and is direct evidence for at least two kinds of different Eu sites in the host with distinct optical activation. Temperature dependent PL and PLE demonstrate that one of the two Eu-centres does not contribute to the room temperature luminescence.
Free carrier induced spectral shift for GaAs filled metallic hole arrays
Optics Express, 2012
For a GaAs filled metallic hole array on a pre-epi GaAs substrate, the free carriers, generated by three-photon absorption (3PA) assisted by strongly enhanced local fields, reduce the refractive index of GaAs in ~200-nm thick active area through band filling and free carrier absorption. Therefore, the surface plasma wave (SPW) resonance, and the related second harmonic (SH) spectrum blue shifts with increasing fluence; For the plasmonic structure on a substrate with surface defects, free carrier recombination dominates. The band gap emission spectral peak wavelength decreases 10-nm with increasing fluence, showing the transition from nonradiative-, at low excitation, to bimolecular-recombination at high carrier concentrations.
Mössbauer Characterization of Magnetite/Polyaniline Magnetic Nanocomposite
2010
Aniline surface coated Fe3O4 nanoparticles have been successfully synthesized by UV irradiation varying the time and the acid media (HCl, HNO3, or H2SO4). The synthesized material represents a promising platform for application in nerve regeneration. XRD patterns are consistent with the crystalline structure of magnetite. Nevertheless, for UV irradiation times longer than 2 h, extra XRD lines reveal the presence of goethite. The mean crystallite size of uncoated particles is estimated to be 25.4 nm, meanwhile that size is reduced to 19.9 nm for the UV irradiated sample in HCl medium for 4 h. Mössbauer spectra of uncoated nanoparticles reveal the occurrence of thermal relaxation at room temperature, while the 77 K-Mössbauer spectrum suggests the occurrence of electron localization effects similar to that expected in bulk magnetite. The Mossbauer spectra of UV irradiated sample in HCl medium during 4 h, confirms the presence of the goethite phase. For this sample, the thermal relaxati...
Molecular BioSystems, 2011
Protein purification, labeling and analysis. Wild-type UmuD, UmuD-S60A, UmuD3A, and UmuD′-A31C were purified following a reported procedure. 1 The A31C variant of UmuD′ was constructed using a QuikChange site-directed mutagenesis kit (Agilent). Protein with a monomer concentration of 300 μM was utilized for EPR. UmuD 2 protein samples (95% purity) were reacted with a thiol-reactive nitroxide derivative, 3-iodomethyl-1-oxy-2,2,5,5-tetramethylpyrroline (iodomethyl spin label, IMSL) for sitedirected spin labeling. This was accomplished by adding an appropriate amount of the 100 mM stock solution of spin label to achieve a molar ratio of 1:3 protein to spin label. The mixture was incubated at 37 ºC for 4 hours and then maintained at 4 ºC overnight. The labeled protein was then dialyzed against exchange buffer [25 mM HEPES (pH 7.5), 150 mM NaCl, 0.1 mM EDTA, 5% glycerol] for at least 24 hours using a Slide-A-Lyzer Dialysis Cassette (Thermo Scientific) with a 3500-Da cutoff membrane. Zeba 7K desalting spin columns (0.5 mL) (Thermo Scientific) were then used to remove residual DTT, and the labeled protein was subsequently stored at-80 ºC. Protein samples were analyzed by using a Bruker EMX instrument outfitted with a high-sensitivity cylindrical cavity and variable-temperature module at 24 ºC (297 K) unless noted otherwise, and the temperature was controlled to within 0.3 ºC by a nitrogen stream. The spectra were obtained at a microwave frequency of 9.37 GHz, 6.0 mW microwave power and 0.5 G 100 kHz field modulation amplitude.
Computer Simulation of Complex Reactions in a Non-Isothermal Continuous Stirred Tank Reactor
2012
The Continuous Stirred Tank Reactor (CSTR) is a reactor type with complex nonlinear characteristics. In this work, the dynamic behaviour of a non-isothermal CSTR for carrying out complex reactions was evaluated. A dynamic model was formulated for this process and simulation was carried out using an advanced process modelling and simulation software. The formulated model was developed from material and energy conservation laws as applied to the reactor. The model is a system of Differential and Algebraic Equations (DAEs) which was simulated at the initial state in order to obtain time trajectories of all variables of interest at steady state. Steady state and dynamic analysis were carried out to study the characteristics of the process. Simulation results showed that an optimum operating condition is an inlet volumetric flowrate of 3 1 0.1 Q m min − =. This is the inlet flowrate that resulted in the maximum value of product concentration. A simulation exercise such as presented in this work is very important and is increasingly becoming popular. This is because simulation of mathematical models of chemical processes is safe, cheap and less time demanding. This has also been helped by the development of computers with high computational capabilities.
Convective Heat Transfer Analysis from Helically Coiled Tube Using CFD and Experimental Methodology
— Continuous research is going on exchanger design and development to fulfill the demand of power sector, refrigeration and air conditioning, chemical industry, nuclear sectors this lead to evolution of helical coil tube heat exchanger. Higher performance and compactness are primary requirements of heat and mass transfer devices hence researchers are endeavor towards heat enhancement techniques with reduction in size of heat exchanger. An attempt is made here to elaborate the effect of constructional feature on these parameters by experimentally and using CFD technique. From several studies of previous authors it has been noted that curvature ratio is most predominant factor in helically coiled tube that affect heat transfer characteristics, hence main objective behind present study is to investigate the effect different curvature ratio helical tubes on single phase fluid flow and convective heat transfer characteristics. CFD simulation and experimental analysis indicates that compactness i.e. surface area density increases with curvature ratios, it is observed that heat flux increase with increase curvature ratio but at the expense of pressure drop in helical tube.
Neutron diffraction structure of Y2V10O28·24H2O at 297 and 60 K
2000
The structure of yttrium-decavanadate-24-hydrate, [Y 2 V 10 O 28 ·24H 2 O], was determined by neutron diffraction at temperatures of 297 and 60 K. Space group P-1, triclinic, Z = 2; at 297 K : a = 9.36 , b = 9.86(1), c = 23.53(3)Å, α = 98.79(2), β = 98.15(2), γ = 89.30(2), V = 2123(5); at 60 K : a = 9.19(3), b = 9.85(3), c = 23.31(12)Å, α = 99.03(3), β = 98.99(6), γ = 89.39(6) • , V = 2058 . Final R factors of 10 and 9.4% were obtained using 1955 and 1100 observed structure factors at both temperatures, respectively. The position of the 24 water molecules was determined and the characteristics of the hydrogen bonds were analyzed at both temperatures.
Coumarinyl(thienyl)thiazoles: Novel Photochromes with Modulated Fluorescence
Organic Letters, 2008
All reagents and solvents purchased were used without purification. Column chromatography was carried out using Merck Kieselgel 60 H silicagel. Analytical thin layer chromatography was carried out using aluminium-backed plates coated with Merck Kieselgel 60 F 254 that were visualised under UV light (at 254 or 363 nm). 1 H NMR spectra were recorded on Bruker AC-200 (200 MHz) and 13 C NMR spectra were recorded on Bruker Avance II 300 (75 MHz). Chemical shifts in CDCl 3 and DMSO-d 6 are reported downfield from TMS (= 0) as internal reference. EIMS spectra were recorded on Kratos MS-30. Absorption spectrometry was performed using a CARY UV 50 (Varian) spectrophotometer. Fluorescence measurements were conducted using a CARY ECLIPSE (Varian) spectrofluorimeter. Absorption and fluorescence spectra were recorded in acetonitrile solution (4 ×