bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrafast intersubband optical switching in II–VI‐based quantum well for optical fiber communications
Authors: Akimoto R. , Li B. S. , Akita K. , Hasama T. 
Published: March 2006

AbstractUltrafast all‐optical switching at optical communication wavelength has been investigated by utilizing an intersubband transition (ISBT) of II–VI‐based multiple quantum wells (MQWs) fabricated in high‐mesa waveguide devices. At first, we have achieved λ ∼ 1.55 µm ISBT absorption in (CdS/ZnSe)/BeTe QWs. The QWs consists of Cl‐doped CdS/ZnSe well and BeTe barrier. The ISBT optical nonlinearity in the wafer sample exhibits sub‐ps relaxation time and sub‐pJ/µm2 saturation energy, indicating a promising characteristic for high‐speed switching. The waveguide device fabricated consists of a CdS/ZnSe/BeTe MQWs core layer and two top and bottom ZnMgBeSe quaternary cladding layers. Ultrafast gate switching within a time window of 0.56 ps was demonstrated with pump pulse at λ = 1.57 µm and probe pulse at λ = 1.63 µm in this waveguide device. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Highly sensitive ultraviolet PIN photodiodes of ZnSSe n+–i–p structure/p+‐GaAs substrate grown by MBE
Authors: Miki K. , Abe T. , Naruse J. , Ikumi K. , Yamaguchi T. , Kasada H. , Ando K. 
Published: March 2006

AbstractHighly sensitive and stable ultraviolet PIN photodiodes of ZnSSe junction structure on p+‐GaAs substrates are developed by molecular beam epitaxy (MBE) growth. The short‐wavelength photodiodes are grown on p‐type (100)GaAs by MBE utilizing an optimized “hetero‐interface super‐lattice (SLE) buffer” consisting of a ZnTe–ZnSe multiple quantum well, by which a large energy barrier (>1 eV) for hole ohmic conduction is overcome. ZnSSe n+–i–p photodiodes with a thin interface SLE are grown in a complete lattice‐matched condition (S = 6%). High sensitivities of 0.30 A/W (external quantum efficiency: η = 83.6%) in the blue (450 nm), 0.24 A/W (η = 75.8%) in the blue–violet (400 nm: for BlueRay and HD‐DVD systems) and 0.12 A/W (η = 50.9%) in the ultraviolet (300 nm) regions are obtained with an extremely low dark leakage current (∼sub pA/mm2) under high reverse bias (20 V) at 300 K. Because of the low dark current, a very low noise equivalent power value below 10–14 W $ \sqrt {{\rm Hz/cm}^{-2}} $ (450 nm) is proved in the blue–violet region. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Yellow–green lasing operations of ZnCdTe/MgZnSeTe laser diodes on ZnTe substrates
Authors: Nomura Ichirou , Manoshiro Asuka , Kikuchi Akihiko , Kishino Katsumi 
Published: March 2006

AbstractZnCdTe/MgZnSeTe laser diodes (LDs) were fabricated on ZnTe substrates by molecular beam epitaxy. The LDs were characterized under single short pulse current injections at low temperature. Yellow–green single‐mode lasing emissions at 564 nm were successfully obtained, for the first time. The threshold current density (J th) at 100 K was 2.8 kA/cm2. The full width at half maximum value of the lasing emission peak was 1.1 meV (0.29 nm). From the temperature dependency of the J th, it was confirmed that the lasing operations were obtained up to 170 K. The characteristic temperature value was estimated to be 228 K. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
ZnxCd1–xSe/Znx′Cdy′Mg1–x′–y′Se multi‐quantum well structures for intersubband devices grown by MBE
Authors: Lu H. , Shen A. , Muñoz M. , Perez‐Paz M. N. , Sohel M. , Zhang S. K. , Alfano R. R. , Tamargo M. C. 
Published: March 2006

AbstractQuantum well infrared photodetectors (QWIPs) from wide bandgap II–VI compounds are promising as high quantum efficiency detectors in the mid‐IR. A series of Cl‐doped ZnxCd(1–x)Se/Znx′Cdy′Mg(1–x′–y′)Se multiple‐quantum‐wells (MQW) with different quantum well (QW) thicknesses have been grown by MBE lattice‐matched to InP substrates. The high material quality of the samples was demonstrated by X‐ray diffraction (XRD), steady‐state photoluminescence (PL), and time‐resolved photoluminescence (t‐PL) measurements. Contactless electroreflectance (CER) measurements were performed to investigate high order transitions within the QWs. From these transitions, intersubband transition energies were predicted and compared with the theoretical calculations, a very useful result for device design. Our results indicate that this material system is very promising for intersubband device applications such as QWIPs operating in the 3–5 µm region. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magneto‐optical spectroscopy of (Zn,Co)O epilayers
Authors: Pacuski W. , Ferrand D. , Cibert J. , Deparis C. , Kossacki P. , Morhain C. 
Published: March 2006

AbstractWe present a magneto‐optical study of (Zn,Co)O layers grown by molecular beam epitaxy. We observed sharp lines related to 4A2–2E intra‐ionic Co2+ transitions, and to the A , B and C excitons. Intra‐ionic transitions observed by absorption and photoluminescence were used to determine the values of the parameters describing the isolated Co ions, such as the easy‐plane magnetic anisotropy and the g ‐factor of the S = 3/2 Cobalt spin. Excitonic transitions observed in reflectivity were used to determine the giant Zeeman splitting and to estimate the effective coupling 〈N 0(α – β )〉A ,B = 0.4 eV between excitons and Cobalt spins. Due to the electron–hole exchange within the exciton, this effective spin–exciton coupling is much weaker than the exchange integrals for free carriers, estimated to be N 0|α – β | ≈ 0.8 eV, with a positive value of (α – β ) if the normal ordering of the valence band of ZnO is assumed. The Zeeman splitting of diluted samples and the magnetic circular dichroism (for a higher Co content) are proportional to the magnetization of the paramagnetic, isolated Cobalt ions. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stimulated emission from ZnO nanorods
Authors: Hauschild R. , Lange H. , Priller H. , Klingshirn C. , Kling R. , Waag A. , Fan H. J. , Zacharias M. , Kalt H. 
Published: March 2006

AbstractThe authors of our Editor's Choice [1] investigate ZnO nanorods by means of time resolved spectroscopy. Resonator and waveguide properties as well as the influence of gold nanoparticles at the nanorod/substrate interface are evaluated using numerical simulations.Part a) of the cover figure shows the intensity distribution of the electric field. As demonstrated in the right part of a), a higher refraction index step at the interface gold/GaN leads to an improved light confinement. Part b) is the cross section perpendicular to the growth direction, and c) a TEM picture of the interface with gold particles appearing as dark droplets.The first author Robert Hauschild is currently a member of the Graduate College “Collective Phenomena in Solids” to pursue a Ph.D. at the University of Karlsruhe (TH). Among his research interests are the optical properties of nano‐ and mesoscopic systems, including excitonic processes in ZnO nanorods and waveguides.This issue of physica status solidi (b) contains a collection of articles presented at The Twelfth International Conference on II–VI Compounds held in Warsaw, Poland, 12–16 September 2005. Further papers from II–VI 2005 are published in phys. stat. sol. (c) 3, No. 4 (2006).
Detection and characterization by high‐performance liquid chromatography and mass spectrometry of two truncated goat αs2‐caseins
Authors: Cunsolo Vincenzo , Muccilli Vera , Saletti Rosaria , Marletta Donata , Foti Salvatore 
Published: March 2006

AbstractThe identification and characterization of truncated forms of goat αs2‐Cn variants A and E are reported. The two proteins, which have experimental Mr values of 24 183 and 24 227 Da, were detected as minor components in a goat milk sample from an autochthonous breed of southern Italy, ‘Rossa Mediterranea’, by reversed‐phase high‐performance liquid chromatography/electrospray ionization mass spectrometry (RP‐HPLC/ESI‐MS). Characterization of the amino acid sequences, performed by coupling trypsin digestion with matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS), RP‐HPLC/ESI‐MS and tandem mass spectrometry (MS/MS), demonstrated that the polypeptide chains correspond to the 1‐204 sequence of mature αs2‐Cn variant A (component with Mr of 24 183 Da) and E (component with Mr of 24 227 Da), respectively. These components seem to be the product of a differential splicing of pre‐messenger RNA during the translation process of the αs2‐Cn variants A and E. Copyright © 2006 John Wiley & Sons, Ltd.
Sublethal exposure from microcystins to renal insufficiency patients in Rio de Janeiro, Brazil
Authors: Soares Raquel M. , Yuan Moucun , Servaites Jerome C. , Delgado Alvimar , Magalhães Valéria F. , Hilborn Elizabeth D. , Carmichael Wayne W. , Azevedo Sandra M. F. O. 
Published: March 2006

AbstractIn November 2001, a cyanobacterial bloom dominated by Microcystis and Anabaena occurred in the Funil Reservoir and the Guandu River, both of which supply drinking water to Rio de Janeiro, Brazil. Using ELISA, microcystins were detected at a concentration of 0.4 μg/L in the drinking water, whereas a concentration of 0.32 μg/L was detected in activated carbon column–treated water for use at the renal dialysis center of Clementino Fraga Filho Hospital (HUCFF) at the Federal University of Rio de Janeiro. A total of 44 hemodialysis patients who received care at this center were believed to be exposed. Initial ELISA analyses confirmed the presence of serum microcystin concentrations ≥ 0.16 ng/mL in 90% of serum samples collected from these patients. Twelve patients were selected for continued monitoring over the following 2‐month period. Serum microcystin concentrations ranged from <0.16 to 0.96 ng/mL during the 57 days after documented exposure. ELISA‐positive samples were found throughout the monitoring period, with the highest values detected 1 month after initial exposure. ESI LC/MS analyses indicated microcystins in the serum; however, MS/MS fragmentation patterns typical of microcystins were not identified. LC/MS analyses of MMPB for control serum spiked with MCYST‐LR. and patient sera revealed a peak at retention time of 8.4 min and a mass of 207 m/z. These peaks are equivalent to the peak observed in the MMPB standard analysis. Taken together ELISA, LC/MS, and MMPB results indicate that these renal dialysis patients were exposed to microcystins. This documents another incident of human microcystin exposure during hemodialysis treatment. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 95–103, 2006.
Specific antioxidant reactions to oxidative stress promoted by natural organic matter in two amphipod species from Lake Baikal
Authors: Timofeyev Maxim A. , Shatilina Zhanna M. , Kolesnichenko Aleksey V. , Kolesnichenko Viktoria V. , Steinberg Christian E. W. 
Published: March 2006

AbstractAquatic organisms are exposed to a variety of natural chemical stressors such as humic substances. The aim of this study was to investigate the mode of action of natural organic matter (NOM, roughly 80% of which is humic substances) on two freshwater amphipods from Lake Baikal, Eulimnogammarus verrucosus (Gerstf.) and Eulimnogammarus cyaneus (Dyb.), in order to assess the potential oxidative stress of NOM impact. Chosen as oxidative stress markers were lipid peroxidation and cell internal hydrogen peroxide level as well as peroxidase, catalase, and glutathione S‐transferase activities. Exposure of amphipods to NOM caused a significant increase in lipid peroxidation but a concomitant decrease in hydrogen peroxide concentration, and peroxidase and (to a lesser degree) glutathione S‐transferase activities. An interim increase of catalase activity was observed. A possible reason for the decrease in major antioxidant enzyme activity is exhaustion of the reservoir of reduced substrates in the first stage of the antioxidant defense reaction. Despite the inhibition of major antioxidant enzymes, the studied amphipods were able to successfully resist the NOM oxidative impact and, at low NOM concentrations, to combat lipid peroxidation processes. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 104–110, 2006.
Cytotoxicity assessment of gliotoxin and penicillic acid in Tetrahymena pyriformis
Authors: Gräbsch C. , Wichmann G. , Loffhagen N. , Herbarth O. , Müller A. 
Published: March 2006

AbstractVarious studies have documented the associations between mold exposure and effects on health. Mycotoxins, which occur in spores and mold fragments, can be involved in processes that have pathological effects, such as adynamia of the immune system, recurrent infections of the respiratory tract, or asthma. Using Tetrahymena pyriformis, a single‐cell organism well established as a suitable model for human respiratory epithelium‐cell functionalities, we investigated dose–response relationships of the mycotoxins gliotoxin and penicillic acid. Our study focused on the viability (cell count, MTT assay), energy levels (adenosine‐5′‐triphosphate content), energy‐providing processes (MTT reduction per cell), and cell respiration (oxygen consumption). Both mycotoxins acted as cytotoxins in a dose‐dependent manner. Gliotoxin had a stronger inhibitory effect (EC50 0.38 μM) than did penicillic acid (EC50 343.19 μM). The energy‐providing processes were not inhibited or were only weakly inhibited under the influence of gliotoxin, whereas penicillic acid caused stimulation of the physiological parameters. Summarizing the results, it is clear that the two investigated mycotoxins must have different modes of action. They are not only different in the strength of their toxic effects but also in a variety of physiological aspects. In addition, T. pyriformis showed differences in its ability to overcome the negative effects of particular mycotoxin exposures. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 111–117, 2006.
QSARs for aromatic hydrocarbons at several trophic levels
Authors: Di Marzio Walter , Saenz Maria Elena 
Published: March 2006

AbstractQuantitative structure–activity relationships (QSARs) with aromatic hydrocarbons were obtained. Biological response was measured by acute toxicity of several aquatic trophic levels. The chemicals assayed were benzene, toluene, ethylbenzene,o‐xylene,m‐xylene,p‐xylene, isopropylbenzene,n‐propylbenzene, and butylbenzene. Acute toxicity tests were carried out withScenedesmus quadricauda, as representative of primary producers;Daphnia spinulata, a zooplanctonic cladoceran;Hyalella curvispina,a benthic macroinvertebrate; andBryconamericus iheringii,an omnivorous native fish. The EC50or LC50was calculated from analytical determinations of aromatic hydrocarbons. Nonlinear regression analysis between the logarithm of the octanol–water partition coefficient (logKow) of each compounds and the toxicity end points was performed. QSARs were positively related to increases in logKowat all trophic levels. Intertaxonomic differences were found in comparisons of algae with animals and of invertebrates with vertebrates. We observed that these differences were not significant with a logKowhigher than 3 for all organisms. Aromatic hydrocarbons with logKowvalues of less than 3 showed different toxicity responses, with algae more resistant than fish and invertebrates. We concluded that this was a result of the narcotic mode of action related to liposolubility and the ability of the compound to reach its target site in the cell. The bioconcentration factor (BCF) achieved to start nonpolar narcosis fell almost 1 order of magnitude below the BCF expected from the logKow. Predicted critical body residues for nonpolar narcosis ranged between 2 and 1 mM. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 118–124, 2006.
Microcystins associated with Microcystis dominated blooms in the Southwest wetlands, Western Australia
Authors: Kemp Annabeth , John Jacob 
Published: March 2006

AbstractPotentially toxic cyanobacterial blooms are becoming common in the freshwater wetlands on the Swan Coastal Plain, Western Australia. During summer the dominant bloom‐causing species belong to the genera Microcystis and Anabaena and to a lesser extent Aphanizomenon and Nodularia. Although toxic cyanobacteria have been recorded in the Swan–Canning and Peel–Harvey estuaries in Western Australia, very little is known about the blooms in the surrounding freshwater lakes. In this study, a total of 32 natural bloom samples representing 13 lakes were analyzed by HPLC for microcystin (MC)–LR, ‐RR, and ‐YR. Twenty‐eight samples proved to be toxic. The highest total microcystin concentration ranged from 1645 to 8428.6 μg L−1, and the lowest concentrations were less than 10 μg L−1 with some below the detection limit (< 0.05 μg L−1). MC‐LR (100%) was the predominant microcystin, followed by MC‐YR (71.4%) and MC‐RR (60.7%). The presence of a Nodularia spumigena bloom in the freshwater Lake Yangebup was associated with the detection of nodularins (1664 μg L−1). This is the first study to demonstrate the presence of microcystins and nodularins in urban lakes on the Swan Coastal Plain, Western Australia. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 125–130, 2006.
Biodegradability testing using standardized microbial communities as inoculum
Authors: Paixão S. M. , Sàágua M. C. , Tenreiro R. , Anselmo A. M. 
Published: March 2006

AbstractReference materials are important tools for maintaining high‐quality assurance standards, including for biological materials. A significant number of environmental international standards, including biodegradability and toxicity, involve utilization of activated sludge (AS) inocula. The absence of inoculum standardization in these tests is a potential source of error influencing the results. In this study three defined microbial consortia, two commercial inocula and a designed bacterial inoculum, were evaluated as an AS alternative seed for the Zahn–Wellens test, using diethylene glycol as the reference chemical. The results showed that to achieve diethylene glycol biodegradation with these inocula, a number of 105 colony‐forming units per milliliter of effective degrader microorganisms had to be present. Moreover, the addition of AS supernatant to the test mixtures improved inocula performance (the biodegradability curves), bringing them closer to those obtained with AS inocula. Among the three defined consortia, the designed inoculum replicates bested the AS behavior in the range of concentrations tested, with degradation completed in 12–14 days. Comparisons of the community substrate utilization profiles corroborated these results, showing that the designed inoculum profile was the most similar to the AS profile. The biodegradability and metabolism results provided support for the assertion that the designed inoculum can be used in the Zahn–Wellens test and as a base to develop reference inocula for other biodegradability and toxicity tests. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 131–140, 2006.
Simplified protocol for evaluating the genotoxic risk of hospital wastewater
Authors: Jolibois B. , Guerbet M. 
Published: March 2006

AbstractTo evaluate the genotoxicity of hospital wastewater, we drew up a simplified protocol based on two well‐known tests: the SOS chromotest and the Ames fluctuation test. Three concentrations of wastewater samples were directly tested without extraction or concentration. By fixing three significance levels in genotoxicity response for each test, we could classify the samples in five categories ranging from nongenotoxic to highly genotoxic. This simplified classification thus constitutes an invaluable help in making the nonscientist public aware of the genotoxic risk of hospital wastewater and can be applied in a screening approach to chemicals in the environment. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 141–146, 2006.
Lead toxicity in Brassica pekinensis Rupr.: Effect on nitrate assimilation and growth
Authors: Xiong Zhi‐Ting , Zhao Fei , Li Min‐jing 
Published: March 2006

AbstractLead is a major heavy‐metal contaminant in the environment that has various anthropogenic and natural sources. To study the phytotoxic effects of Pb on the popular vegetable Chinese cabbage (Brassica pekinensis Rupr.) via depression of nitrogen assimilation, pot culture experiments with three concentrations of treatment with Pb (0, 4, and 8 mmol/kg dry soil) were carried out. Our results demonstrated adverse effects of Pb on nitrogen assimilation and plant growth. The addition of Pb in the soil resulted in elevated accumulation of Pb in the shoots of the plants: Pb concentrations of 14.3, 202.3, and 418.2 mg/kg (DW) in the shoots were detected with the 0, 4, and 8 mmol/kg treatments, respectively. Compared to the control, Pb exposure (4 and 8 mmol/kg) significantly decreased shoot nitrate content (71% and 80% of the control), nitrate reductase activity (104% and 49% of the control), and free amino acid content (81% and 82% of the control), indicating decreased nitrogen assimilation in the plants. The effect of Pb also was shown by the progressive decline in shoot biomass with increasing Pb concentration in plant shoots and in the soil. However, at the treatment levels used in this study, lead did not induce visible toxic symptoms. The lowest‐concentration Pb treatment (4 mmol/kg) stimulated chlorophyllb content but did not influence chlorophyll a content. The results suggested that the toxicity of Pb to the plants occurred at least partly via depression of nitrogen assimilation. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 147–153, 2006.
Tributyltin induces DNA damage as well as oxidative damage in rats
Authors: Liu Hui‐Gang , Wang Yan , Lian Lingjun , Xu Li‐Hong 
Published: March 2006

AbstractIn this study, oxidative and DNA damage were measured synchronously after Sprague–Dawley rats were exposed to different dosages of tributyltin (TBT) for 3 and 7 consecutive days. Oxidative damage was measured by analyzing the production of hepatic reactive oxygen species (ROS), the activity of superoxide dismutase (SOD), and the content of malondialdehyde (MDA). DNA damage was measured by single‐cell gel electrophoresis (comet assay). After 3 days of exposure, significant differences in ROS production could only be seen between the control and the highest dosage group (10 mg/kg BW d), although after 7 days of treatment, ROS production increased in a dose‐dependent manner. SOD activity increased with dosage after 3 days of exposure and decreased with dosage after 7 days of exposure. TBT also induced significant production of MDA after 7 days of exposure. The changes in ROS, SOD, and MDA found in this study suggest that the antioxidative systems of rats were activated by TBT in the first 3 days of exposure but had become exhausted by 7 days of exposure. In the comet assay, the number of cells with damaged DNA in rats treated with TBT increased with dosage of TBT. The most likely mechanism of the DNA breakage induced by TBT is oxidative damage. It can be concluded that exposure of TBT can promote both oxidative and DNA damage in mammals in vivo. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 166–171, 2006.
Herbage yield and economic viability of grass (Panicum colaratum) and legume (Trifolium prantese) mixtures under variable seed rates in the eastern highlands of Ethiopia
Authors: Tamir Berhan 
Published: March 2006

AbstractMixtures of grass (Panicum colaratum) and legume (Trifolium prantese) at seed rates of 50 : 50% produced (p < 0.001) higher herbage dry matter yield and was biologically and economically more competitive and viable than 25 : 75% and 75 : 25%, since it had the highest land equivalent ratio and the best monetary advantage (US$219) and net return (US$144). Copyright © 2006 John Wiley & Sons, Ltd
Biological potential and economic viability of grass (Chloris gayana) and legume (Stylosanthes guianensis) associations under variable seed rates in the eastern highlands of Ethiopia
Authors: Tamir Berhan 
Published: March 2006

AbstractAssociation of grass (Chloris gayana) and legume (Stylosanthes guianensis) at seed rates of 50 : 50% produced significantly (p < 0.001) more herbage dry matter yield and was biologically more competitive than 25 : 75%, 75 : 25% or the sole stand, since it had the highest land equivalent ratio and the best monetary advantage (US$240) and net return (US$165). Copyright © 2006 John Wiley & Sons, Ltd