bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and optical properties of CdSe nanocrystals and CdSe/ZnS core/shell nanostructures in non-coordinating solvents
Authors: Nguyen Hong Quang 
Published: August 2010

Abstract
We have performed a conventional and non-coordinated-based method for synthesis of CdSe and CdSe/ZnS core/shell quantum dots in this work. This was the first time a CdSe/ZnS core/shell structure was successfully synthesized in a non-coordinating solvent without trioctylphosphine oxide (TOPO). The obtained CdSe nanocrystals were characterized by using UV-Vis absorption spectroscopy, photoluminescent (PL) spectroscopy and transmission electron microscopy (TEM), which confirmed that a series of CdSe particles with a diameter of 1.9–3.5 nm, corresponding to the first peak of absorption spectra in the 450–570 nm range, was successfully achieved. The CdSe/ZnS core/shell structures were then fabricated by coating the previously synthesized CdSe core with various ZnS layers. These CdSe/ZnS semiconductor quantum dots exhibited very high photoluminescence in comparison to that of the original CdSe cores. The narrow width of the CdSe/ZnS quantum dots indicated that the as-produced quantum dots have uniform size distribution, desirable dispersibility and excellent fluorescent properties. These are the requirements for several potential utilizations, such as cellular imaging, biomedical sensing, and solar cell and other photovoltaic applications.
Time-resolved photoluminescence study of CuInS
2/ZnS nanocrystals
Authors: Tran Thi Kim Chi , Le Quang Phuong , Nguyen Quang Liem , Li Liang , Reiss Peter 
Published: August 2010

Abstract
The emission mechanism in ZnS-capped 3-nm CuInS
2 nanocrystals was studied by using time-resolved photoluminescence (TRPL). A typical TRPL spectrum demonstrates two broad emission bands. The spectral shifts as functions of the excitation power density and delay times from the excitation moment prove that both emission bands originate from donor-acceptor pair recombinations. Moreover, the temperature-dependent TRPL measurement revealed the importance of trapping sites in the emission mechanism of CuInS
2 nanocrystals.
Preparation and characterization of ZrO
2:Er
3+, Yb
3+ nanoparticles using a high pressure assisted soft template
Authors: Lam Thi Kieu Giang , Opalinska A , Chudoba T , Benkowski K , Lojkowski W , Tran Kim Anh , Nguyen Thanh Binh , Le Quoc Minh 
Published: August 2010

Abstract
Nanoparticles of ZrO
2:Er
3+, Yb
3+ fabricated by a soft template method combined with microwave heating under high pressures were reported for the first time. Nano ZrO
2:Er
3+, Yb
3+ in concentrations of 0.1–15 mol% have been fabricated in the presence of soft template agent diethylene glycol or polyethylene glycol in a microwave reactor at pressures up to 55 atm. The average size of the as-synthesized nanoparticles was found to be 5–13 nm. The upconversion luminescence of the ZrO
2:Er
3+, Yb
3+ was found in the red region of 630–710 nm and in the green region of 510–570 nm, with excitation by an infrared diode laser at the wavelengths of 830 and 940 nm, respectively. The change in content ratio between monoclinic and tetragonal phases when the annealing temperature increases from 600 to 1200 °C was investigated. The tetragonal phase content decreases and disappears for the samples annealed at 1200 °C. The increase in the content of the monoclinic phase is suggested to be a main reason for the increase in the upconversion luminescent intensity of nano ZrO
2:Er
3+, Yb
3+.
LPG sensing properties of SnO
2 nanoparticles doped with several metal oxides by a hydrothermal method
Authors: Hien Vu Xuan , Anh Ly Tu Huy , Trung Khuc Quang , Vuong Dang Duc , Chien Nguyen Duc 
Published: August 2010

Abstract
CuO, Al
2
O
3, Ag
2
O and La
2
O
3 doped on SnO
2 nanoparticles were successfully fabricated by a hydrothermal route at 200 °C for 3 h. The morphology and composition were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and energy dispersive x-ray analysis (EDX). The results showed that the particle size is 6–8 nm without other impurities. The influence of CuO with a concentration of 0.5–3wt%, which was doped on sol SnO
2 5wt% by hydrothermal and vibration technique, was discussed. In addition, the gas sensitivity experiment of samples to 1% LPG in the temperature range of 230–430 °C indicated the improvement in sensitivity and response time. In particular, the SnO
2 sol suspension 5wt% doped with CuO 2wt% showed the best sensitivity at 330 °C.
The fabrication of GaN-based light emitting diodes (LEDs)
Authors: Nguyen Xu Lin , Nguyen Thi Ngoc Nhien , Chau Vinh Thang , Dang Mau Chien 
Published: August 2010

Abstract
In this paper, we report on the fabrication of blue GaN based light emitting diodes (LEDs), and then on coating procedures to obtain white LED lamps from blue LED chips. Firstly, the multi-layers of nanometer thickness GaN are grown on quarters of 2-inch diameter (0001)-orientation (c-plane) sapphire substrates by using metal organic chemical vapor deposition (MOCVD) for a subsequent realization of the LED structures. Then, the blue GaN based LEDs are fabricated by using several standard microfabrication techniques, including mesa etching, metal deposition, lift-off and annealing. The luminous intensity of the fabricated blue LED chips, measured with a current of 20 mA, is approximately 80 millicandela (mcd). Afterward, a solution of phosphor (Y
3
Al
5
O
12:Ce): epoxy is prepared to coat the blue LED chips, thus obtaining the white LED lamps. After the coating procedure, the power of the fabricated white LED lamps is about 40 lm
W
-1 at 20 mA current. All the obtained results have proved the success of the GaN-based LED fabrication and white LED lamps produced.
Abscisic Acid Increases Arabidopsis ABI5 Transcription Factor Levels by Promoting KEG E3 Ligase Self-Ubiquitination and Proteasomal Degradation
Authors: Liu Hongxia , Stone Sophia L. 
Published: August 2010

Abstract
The Arabidopsis thaliana RING-type E3 ligase KEEP ON GOING (KEG) is a negative regulator of abscisic acid (ABA) signaling. Seedlings homozygous for T-DNA insertions in KEG accumulate high levels of the ABA-responsive transcription factor ABSCISIC ACID-INSENSITIVE5 (ABI5). Here, we demonstrate that KEG E3 ligase activity is required for the regulation of ABI5 abundance. KEG ubiquitinates ABI5 in vitro, and a functional KEG RING domain is required to restore the levels of ABI5 in keg-1 to that of the wild type. Overexpression of KEG leads to ABA insensitivity, which correlates with KEG protein levels. In the presence of ABA, ABI5 levels increase drastically via a decrease in ubiquitin-meditated proteasomal degradation. Our results indicate that ABA promotes ABI5 accumulation by inducing the ubiquitination and proteasomal degradation of KEG. A functional RING domain is required for the ABA-induced degradation of KEG, suggesting that the loss is due to self-ubiquitination. Mutations within KEG's kinase domain or treatments with kinase inhibitors prohibit the ABA-induced ubiquitination and degradation of KEG, indicating that phosphorylation, possibly self-phosphorylation, is involved in the ABA regulation of KEG protein levels. We discuss a model for how ABA may negatively regulate KEG protein abundance, leading to accumulation of ABI5 and ABA-dependent cellular responses.
The physiological significance of cyanide‐resistant respiration in higher plants
Authors: LAMBERS HANS 
Published: August 2010

Abstract A brief survey of the biochemistry of the alternative oxidative pathway (‘cyanide‐resistant respiration’) and its occurrence in vivo is given. Several hypotheses about the physiological significance of the alternative chain are discussed. These include a role in (1) heat production, (2) fruit ripening, (3) respiration of plants that contain high levels of cyanogenic glycosides, producing HCN upon wounding, (4) oxidation of NADH that is produced by various causes in excess of that required for ATP production, (5) ion uptake, and (6) osmoregulation.In intact roots of higher plants, the activity of the alternative pathway is more active when less carbohydrate is required for assimilation of N (NH+4 NO‐3 or N2) and is less active in those when carbohydrates are being stored in a storage organ or when the availability of photosynthate is reduced. An increase in carbohydrate requirement for osmoregulation is also correlated with decreased alternative chain activity.It is concluded that the alternative pathway in roots plays an important role in oxidation of sugars which are not required for carbon skeletons, energy production for growth and maintenance processes, osmoregulation or storage. However, the significance of this role may vary in different tissues and physiological states.
CHEMOSENSORY RESPONSES OF THE SYMBIOTIC DINOFLAGELLATE SYMBIODINIUM MICROADRIATICUM (DINOPHYCEAE)1
Authors: Fitt William K. 
Published: August 2010

ABSTRACTMotile Symbiodinium microadriaticum (Freudenthal 1962) were attracted to a variety of nitrogen‐containing compounds, including ammonium, nitrate, urea and some amino acids. No chemosensory response to phosphate, sulphate, vitamins, trace metals or sugars was evident. Motile algae responded to concentrations of ammonium, nitrate, and urea at least as low as 10−6 M. High concentrations (≥ 10−2 M) of ammonium appeared to inhibit attraction of motile algae. Calculations using ammonium release rates from various aposymbiotic hosts suggest that motile S. microadriaticum can respond to released ammonium ca. 1 cm from the source.Cultured algae were not attracted to combined nitrogen cues for at least 2 days after inoculation into seawater with dissolved combined low nitrogen. Algae freshly isolated from starved animals were normally motile the day following isolation and attracted to ammonium and nitrate when maintained in seawater containing < 1 μM ammonium and nitrate. The algae lost their ability to orient to nitrogen attractants the day after incubation into culture medium containing high levels of ammonium and nitrate. These results suggest that chemosensory behavior is suppressed when nutrients are present in the ambient medium or are stored by the alga.There were few differences in chemosensory abilities in different strains of S. microadriaticum to the attractants assayed, suggesting that selection for a particular strain by a host species may not be due to differential chemosensory ability or cues. However, the absence of chemical attraction of motile S. microadriaticum to infected hosts may act to preserve strain selection occurring at other steps in the infection process of aposymbiotic hosts.
STUDIES ON THE BIOGEOGRAPHY AND ECOLOGY OF THE FRESHWATER PHAEOPHYCEAN ALGA HERIBAUDIELLA FLUVIATILIS1
Authors: Wehr John D. , Stein Janet R. 
Published: August 2010

ABSTRACTA biogeographical survey of the freshwater brown alga Heribaudiella fluviatilis (Areschoug) Svedelius was conducted in southern British Columbia (Canada) and northern Washington (U.S.A.). Surveys of 121 reaches on streams and rivers revealed 25 populations, including the first record for the U.S.A. A strongly noncoastal distribution provides no evidence of a marine‐based source for its distribution in the region. Streams with Heribaudiella typically have a: current velocity greater than 1.0 m · s−1; rocky substrata; range of width from 1.7–60 m; broad range of Ca concentration; and, ranged from heavily shaded to fully open location. Although once thought rare in North America, it was fairly widespread in the region and often abundant within a given sampling site. Biogeographic and ecological data suggest that Heribaudiella may be a common, but often overlooked, component of the flora of rivers.
A SHORT‐TERM DEMOGRAPHIC STUDY OFCYSTOSEIRA OSMUNDACEA(FUCALES: CYSTOSEIRACEAE) IN CENTRAL CALIFORNIA1
Authors: Schiel David R. 
Published: August 2010

ABSTRACTSeveral demographic features were examined in the field over a period of eleven months for the subtidal algaCystoseira osmundacea(Turner) C. Agardh at two localities near Monterey, California. This species showed a restricted distribution with depth, with peak average numbers of 3–4 plants per m2occurring at 6–8 m and forming a dense canopy on the surface of the sea. Below 10 m depth, there was a decline in the abundance of plants and also in the proportion of plants which bore seasonal fronds and reproductive tissue.Macrocystis pyrifera(L.) C. Agardh plants were also common at both localities. There was a negative correlation between the presence of this species andC. osmundaceaat a scale of 1 m2, but no correlation at 4, 9, and 25 m2.Cohorts ofC. osmundaceawere mapped and tagged at one locality. The plants had markedly seasonal growth, with the greatest elongation of fronds occurring between March and June. Dense surface canopies and reproductive tissue were present during the summer months of June–August. These seasonal fronds were shed during September, leaving small perennial holdfasts and fronds.Plants were strictly dioecious, and there was a one‐to‐one ratio of male to female plants at both localities. Length‐dry weight relationships showed that the largest plants had over 80% of their weight invested in seasonal fronds (vegetative plus reproductive tissue).Recruits ofC. osmundaceaat one locality appeared during September–November only in areas cleared to bare substratum. There was 15% survival of recruits between November and the following May, while 98% of the original mapped cohort survived for the 11 months of the study.
ULTRASTRUCTURE OF THE FLAGELLA OF THE COLORLESS PHAGOTROPH PERANEMA TRICHOPHORUM (EUGLENOPHYCEAE).II. FLAGELLAR ROOTS1
Authors: Hilenski Lula L. , Walne Patricia L. 
Published: August 2010

ABSTRACT Peranema trichophorum (Ehrenberg) Stein, a colorless phagotrophic euglenoid flagellate, has a typically euglenoid microtubular root complement. Striated root components, relatively uncommon in euglenoids, are connected to the basal bodies and to a microtubular root.The flagellar system of Peranema consists of three unequal microtubular roots which extend anteriorly beneath the reservoir membrane, and narrow‐band striated roots (periodicity = 29–33 nm) which connect one of the four basal bodies to the movable rodorgan of the feeding apparatus. An inter basal body striated fiber forms a three‐way connection between one particular microtubular root, a flagellar basal body, and the striated roots. A striated fibril (periodicity = 18–25 nm), which may be an extension of the striated root system, extends beneath the reservoir membrane. Associated with the striated fibril and the striated roots are cisternae of smooth endoplasmic reticulum.
CHROOCOCCOID CYANOBACTERIA IN LAKE ONTARIO: VERTICAL AND SEASONAL DISTRIBUTIONS DURING 19821
Authors: Caron David A. , Pick Francis R. , Lean David R. S. 
Published: August 2010

ABSTRACTChroococcoid cyanobacteria (0.7–1.3 μm in diameter) were discovered to be a significant component of the Lake Ontario plankton. Using epifluorescence microscopy, the densities of these microorganisms were found to vary by four orders of magnitude with a single large peak in abundance (6.5 × 105 cells mL−1) corresponding to the time of maximum water temperature. The morphology and abundance of these cyanobacteria were similar to those previously found in oceanic systems. They constituted 10% of the bacterial numbers in the epilimnion during this period, approximately 40% of the biomass of prokaryotes less than 2.0 μm, and 30% of the biomass of all microorganisms less than 20 μm in size. Size fractionation studies indicated that they were responsible for approximately 38% of the total primary production during times of peak abundance, and were important in phosphorus uptake. Cyanobacteria observed in the food vacuoles of heterotrophic microflagellates and in the guts of rotifers suggest that the latter organisms may be important consumers of this prokaryote population.
EFFECTS OF CHIRONOMID (INSECTA: DIPTERA) TUBE‐BUILDING ACTIVITIES ON STREAM DIATOM COMMUNITIES1,2
Authors: Pringle Catherine M. 
Published: August 2010

ABSTRACTChironomid retreats, constructed out of sand grains upon submerged wood debris, increase the surface area available for diatom colonization. The three dimensional substratum afforded by chironomid tubes supports up to twelve times the diatom biavolume found upon adjacent, unmodified substratum in a northern Michigan stream. Diatom enumeration within scrapings from small defined areas on artificial substrata, combined with examination of intact natural substrata through scanning electron microscopy (SEM), reveals distinct, microdistribution patterns. The larval retreats of two major taxa of tube‐dwelling chironomid's(Micropsectrasp. andPseudodiamesacf.pertinaxGarrett) display significantly different diatom communities relative to adjacent masonite substratum. Substratum without chironomid tubes is primarily colonized byAchnanthes minutissimaKütz. andCocconeis placentulaEhr., exhibiting the lowest species diversity of microhabitats examined. The diatom flora upon sand tubes ofMicropsectrasp. is dominated byOpephora martyiHerib., as is the flora of sand grains collected from the stream sediment load. These two micro‐habitats exhibit a high community similarity (SIMI). The SIMI index also suggests that the flora ofP. pertinaxtubes is highly similar to that of sand grains. Diversity, however, is almost three times greater onP. pertinaxtubes and SEM observations reveal that this microhabitat is characterized by a more spatially complex flora; NitzschiaandNaviculaspp. dominate the upperstory, andO. martyiis located on underlying sand grains. Results indicate that tube‐building chironomids in Carp Creek affect diatom microdistribution by: (1) stabilizing sand grains and associated flora within their retreats, (2) providing a ‘refugium’ for upperstory diatom taxa from the mayfly grazer,Baetis vagansMcDunnough (Insecta: Ephemeroptera), and (3) through local nutrient enrichment.
COMPARATIVE pH DEPENDENT METAL INHIBITION OF NUTRIENT UPTAKE BY SCENEDESMUS QUADRICAUDA(CHLOROPHYCEAE)1,2
Authors: Peterson Hans G. , Healey F. Patrick 
Published: August 2010

ABSTRACTCadmium and copper inhibition of nutrient uptake by the green alga Scenedesmus quadricauda is highly pH dependent in an inorganic medium; both metals are less toxic at low pH. The alga was grown in chemostats with both N and P approaching limiting levels; it was then possible to study metal toxicity to the nitrate, ammonium, and phosphate uptake systems of algae in an identical physiological state. When the logarithm of the Cd concentration causing 25% inhibition of nitrate, ammonium, and phosphate uptake was regressed against pH almost perfect linear relationships were obtained. This was also true at the 50% inhibition level, except for a smaller than predicted increase in Cd toxicity to ammonium uptake at pH 8, which may be due to the beginning of Cd precipitation at this pH. Cu2+ toxicity was linearly related to pH for ammonium and phosphate uptake and although, its toxicity for nitrate uptake also increased with pH, the increase was not perfectly linear. The toxicity of total Cu showed no linear relationship to pH. Cd2+ and Cu2+ toxicity increased by up to four orders of magnitude from pH 5 to 8. Competition between free metal and hydrogen ions for uptake sites on the cell surface is suggested as a mechanism increasing the toxicity of free metal, ions as the hydrogen ion content decreases (i.e. at higher pH).
GROWTH RATE VARIATION IN THE N:P REQUIREMENT RATIO OF PHYTOPLANKTON1
Authors: Terry Kenneth L. , Laws Edward A. , Burns Deborah J. 
Published: August 2010

ABSTRACTTheoretical considerations predict that the cell N:P ratio at transition from nitrogen limitation to phosphorus limitation of phytoplankton growth (critical ratio, Rc) varies, as a function of population growth rate. This prediction is confirmed by experimental, data from the literature along with new experimental data for the marine, prymnesiophyte Pavlova lutheri (Droop) Green. Rc passes through a maximum at intermediate growth rates for the three phytoplankton species for which data, are available, but there is significant interspecific variability in its value. There is no theoretical or experimental evidence to support the idea that the ratio of subsistence N and P cell quotas is equal to Rc over the range of growth rates, or that the subsistence quota ratio equals the ratio of the N and P cell quotas minus a storage fraction. Examination of N:P composition ratios can be used to determine which nutrient is limiting, but cannot be used to determine relative growth rates or competitive advantage between species limited by the same nutrient. Growth rates are determined by environmental conditions and by the cell quota of the limiting nutrient, without reference to the cell quota of the non‐limiting nutrient.
CYANOPHYTE AND CYANELLE DNA: A SEARCH FOR THE ORIGINS OF PLASTIDS1
Authors: Coleman Annette W. 
Published: August 2010

ABSTRACTCyanophyte‐like prokaryotes are widely presumed to be the progenitors of eukaryote plastids. A few rare protistan species bearing cyanophyte‐like cyanelles may represent intermediate stages in the evolution of true organelles. Cyanophyte DNA disposition in the cell, so far as is known from electron microscopy, seems uniform within the group and distinctly different from the several known arrangements of DNA in plastids. Therefore a survey of representative cyanophytes and protistan cyanelles was undertaken to determine whether forms reminiscent of plastids could be found. DNA‐specific fluorochromes were utilized, along with epifluorescent microscopy, to study the DNA arrangement in situ in whole cells.Only the endospore (baeocyte)‐forming Cyanophyta contained more than one, centrally located DNA skein per cell, and then only for the period just preceding visible baeocyte formation. Such forms might, with modification, presage the “scattered nucleoid” DNA disposition found in plastids of several groups, including Rhodophytes, Cryptophytes, Chlorophytes and higher plants. The DNA arrangement in cyanelles of two protists, Cyanophora and Glaucocystis, appear different from each other and possibly related to, respectively, the cyanophytes Gloeobacter and Synechococcus. Cyanelles of the third protist, Glaucosphaera, like the cells of the unique prokaryote Prochloron, appear to have multiple sites of DNA, somewhat similar to those of the “scattered nucleoid” line of plastid evolution. No obvious precursor of the “ring nucleoid” or other types of plastid DNA conformation was found.
OBSERVATIONS ONLOPHODINIUM POLYLOPHUM(DINOPHYCEAE)1
Authors: Carty Susan , Cox Elenor R. 
Published: August 2010

ABSTRACTLophodinium polylophum(Daday) Lemmermann is reported from a Texas pond. Cells have distinctive longitudinal ridges, an apical carina and slit, numerous golden chloroplasts, an eyespot, and a typical dinoflagellate nucleus. The theca appears to be composed of hexagonal plates. The genus is allied toWoloszynskiaThompson, family Lophodiniaceae, but probably not to the fossilDinogymnium.