Home About us Contact
|
Home About us Contact | ||
|
|
||
Wavelengths Longer (wavelength + longer)
Selected AbstractsAnalysis and objective mapping of extreme daily rainfall in CataloniaINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 3 2007M. Carmen Casas Abstract The main objective of this study is to determine the maximum daily precipitation in Catalonia for several established return periods with a high spatial resolution. For this purpose, the maximum daily rainfall annual series from 145 pluviometric stations of the Instituto Nacional de Meteorología (INM) (Spanish Weather Service) in Catalonia have been analyzed. Using the L-moments method of Hosking, every series has been fitted by the extreme value distribution function of Gumbel. From this fitting, the maximum daily precipitation for each of the pluviometric stations corresponding to return periods between 2 and 500 years, have been determined. Applying the Cressman method, the spatial analysis of these values has been achieved. Monthly precipitation climatological data, obtained from the application of Geographic Information Systems (GIS) techniques, have been used as the initial field for the analysis. The maximum daily precipitation at 1 km2 spatial resolution on Catalonia has been objectively determined by the method employed, and structures with wavelength longer than approximately 35 km can be identified. The results show that places where the maximum daily precipitation values are expected are the zone of Guilleries in the Transversal Range, in the highest zones of the Catalan Pyrenees and Cape Creus zone at the northeastern end of Catalonia and in the south, around the Prelittoral Mountain Range between the Mountains of Prades and Montsià. A good fit between the distribution of minimum values and the driest Catalan areas has been found, the lowest values being on the western end of the Central Basin. Copyright © 2006 Royal Meteorological Society. [source] Synthesis and properties of conjugated polymers containing 3,9- and 2,9-linked carbazole units in the main chainJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 14 2009Kosaku Tamura Abstract Novel conjugated polymers containing 3,9- or 2,9-linked carbazole units in the main chain were synthesized by the polycondensation of ethynyl- and iodo-substituted 9-arylenecarbazolylene monomers, and their optical and electrical properties were studied. Polymers with weight-average molecular weights of 3400,12,000 were obtained in 76,99% yields by the Sonogashira coupling polycondensation in piperidine or tetrahydrofuran (THF)/piperidine at 30 °C for 48 h. All the 3,9-linked polymers absorbed light around 300 nm. The para -phenylene-linked polymer also absorbed light around 350 nm, while meta -phenylene-linked one did not. The 3,9-linked polymers absorbed light at a wavelength longer than the 2,9-linked one. The polymers emitted blue fluorescence with high quantum yields (0.21,0.78) upon excitation at the absorption maxima. The polymers were oxidized around 0.6 V, and reduced around 0.5 V. Poly(1) showed the dark conductivity of 3.7 × 10,11 S/cm (103 V/cm). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3506,3517, 2009 [source] Photoreflectance investigations of energy level structure of InAs quantum dashes embedded in InGaAs/InGaAlAs quantum well grown on InP substratePHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2006W. Rudno-Rudzi Abstract Photoreflectance (PR) and photoluminescence measurements have been performed on molecular beam epitaxy grown InAs quantum dashes (QDash) of various sizes, embedded in In0.53Ga0.47As/In0.53Ga0.23Al0.24As quantum well (QW), grown on InP substrate. PR response from all relevant parts of the structure, i.e InAs/In0.53Ga0.47As QDashes, InAs/In0.53Ga0.47As/In0.53Ga0.23Al0.24As QW, and In0.53Ga0.23Al0.24As barriers, has been obtained. The lowest energy transition related to the ground state transition in QDashes shifts towards red with the increase in QDash sizes (amount of deposited InAs material) reaching wavelengths longer than for structures without the intermediate QW. The experimental data on the energies of optical transitions combined with the numerical calculation within the effective mass approximation has allowed determining the energy level structure of the entire system, including the values of conduction band offset between InGaAs and InGaAlAs layers. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Photomorphogenic regulation of increases in UV-absorbing pigments in cucumber (Cucumis sativus) and Arabidopsis thaliana seedlings induced by different UV-B and UV-C wavebandsPHYSIOLOGIA PLANTARUM, Issue 1 2010James R. Shinkle Brief (1,100 min) irradiations with three different ultraviolet-B (UV-B) and ultraviolet-C (UV-C) wave bands induced increases the UV-absorbing pigments extracted from cucumber (Cucumis sativus L.) and Arabidopsis. Spectra of methanol/1% HCl extracts from cucumber hypocotyl segments spanning 250,400 nm showed a single defined peak at 317 nm. When seedlings were irradiated with 5 kJ m,2 UV-B radiation containing proportionally greater short wavelength UV-B (37% of UV-B between 280 and 300 nm; full-spectrum UV-B, FS-UVB), tissue extracts taken 24 h after irradiation showed an overall increase in absorption (91% increase at 317 nm) with a second defined peak at 263 nm. Irradiation with 1.1 kJ m,2 UV-C (254 nm) caused similar changes. In contrast, seedlings irradiated with 5 kJ m,2 UV-B including only wavelengths longer than 290 nm (8% of UV-B between 290 and 300 nm; long-wavelength UV-B, LW-UVB) resulted only in a general increase in absorption (80% at 317 nm). The increases in absorption were detectable as early as 3 h after irradiation with FS-UVB and UV-C, while the response to LW-UVB was first detectable at 6 h after irradiation. In extracts from whole Arabidopsis seedlings, 5 kJ m,2 LW-UVB caused only a 20% increase in total absorption. Irradiation with 5 kJ m,2 FS-UVB caused the appearance of a new peak at 270 nm and a concomitant increase in absorption of 72%. The induction of this new peak was observed in seedlings carrying the fah1 mutation which disrupts the pathway for sinapate synthesis. The results are in agreement with previously published data on stem elongation indicating the existence of two response pathways within the UV-B, one operating at longer wavelengths (>300 nm) and another specifically activated by short wavelength UV-B (<300 nm and also by UV-C). [source] Crosslinking of elastomers upon ageing: a kinetic approach based on crystallinity changes followed by DSCPOLYMER INTERNATIONAL, Issue 6 2003Mohamed Baba Abstract It was observed that crosslinking reactions resulting both from peroxide decomposition or photoageing at wavelengths longer than 300,nm involve a drastic decrease of the crystallinity of some dienic elastomers, such as polybutadienes (rich in cis 1,4 and 1,2 microstructures) and polycyclo-octene. By comparing precisely the rate of decomposition of dicumyl peroxide and that of the crystallinity decrease, it was possible to show that the kinetics of crystallinity loss observed upon ageing can be identified with that of the crosslinking of elastomers. The results indicate that the crosslinking process can be followed directly by DSC measurement of the crystallization/melting cycle. © 2003 Society of Chemical Industry [source] Synchrotron white-beam X-ray topography of ribonuclease S crystalsACTA CRYSTALLOGRAPHICA SECTION D, Issue 4 2002W. M. Vetter With careful experimental design, indexed synchrotron white-beam X-ray topographs of ribonuclease S crystals at ambient temperature could be recorded with a definition and contrast comparable to that of monochromatic beam topographs of other proteins reported in the literature. By excluding wavelengths longer than 1,Å from the white beam with a filter, a radiation dose equivalent to that required to record about 18 topographs could be tolerated without appreciable radiation damage to the samples. Bragg angles of 0.5° or less were required to select low-index harmonically pure reflections with high intensities and extinction lengths only several times the sample's thickness. The resulting X-ray topographs in some cases showed topographic detail and in others showed the even featureless background that has been considered characteristic of a protein crystal of low mosaicity. The ribonuclease S crystals were well ordered single crystals of a quality comparable to other protein crystals that have been studied by X-ray topography. [source] Efficient UV detection of protein crystals enabled by fluorescence excitation at wavelengths longer than 300,nmACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 4 2010Karsten Dierks It is well known that most proteins and many other biomolecules fluoresce when illuminated with UV radiation, but it is also commonly accepted that utilizing this property to detect protein crystals in crystallization setups is limited by the opacity of the materials used to contain and seal them. For proteins, this fluorescence property arises primarily from the presence of tryptophan residues in the sequence. Studies of protein crystallization results in a variety of setup configurations show that the opacity of the containment hardware can be overcome at longer excitation wavelengths, where typical hardware materials are more transparent in the UV, by the use of a powerful UV-light source that is effective in excitation even though not at the maximum of the excitation response. The results show that under these circumstances UV evaluation of crystallization trials and detection of biomolecular crystals in them is not limited by the hardware used. It is similarly true that a deficiency in tryptophan or another fluorescent component that limits the use of UV light for these purposes can be effectively overcome by the addition of fluorescent prostheses that bind to the biomolecule under study. The measurements for these studies were made with a device consisting of a potent UV-light source and a detection system specially adapted (i) to be tunable via a motorized and software-controlled absorption-filter system and (ii) to convey the excitation light to the droplet or capillary hosting the crystallization experiment by quartz-fibre light guides. [source] | |||||||||||||