Pale Green Color Research Articles

Manglietia guangnanica(Magnoliaceae), a New Species from Yunnan, China

Manglietia guangnanica D. X. Li & R. Z. Zhou (Magnoliaceae), a new species from Yunnan, China, is described and illustrated. Its pollen morphology, ecology, and conservation status are presented. Manglietia guangnanica is closely related to M. pachyphylla Hung T. Chang, M. crassipes Y. W. Law & M. fordiana Oliv. The new species is distinguished from M. pachyphylla by its narrower leaves (4–6 cm vs. 6–10 cm), the glabrous abaxial surfaces (vs. pubescent), the shorter peduncles (1.4–1.8 cm vs. 2.3 cm) and pedicels (0.4–0.6 cm vs. 0.7–1.8 cm), the smaller gynoecia (1.7–1.9 cm vs. 2.1–2.9 cm) and fewer carpels (29 to 34 vs. 54 to 61), and fewer ovules (six to eight vs. [eight]nine to 17[18] ovules per carpel). Manglietia guangnanica differs from M. crassipes by its narrower leaves (4–6 cm vs. 6–9.3 cm), the ovoid gynoecia and flower buds (vs. elliptic), the sparse sericeous indument on the buds, the pale green color of the branchlets and abaxial blade surfaces (vs. these surfaces glaucous), and the fewer carpels (29 to 34 vs. 37 to 40) and ovules (six to eight vs. eight to 13[14] ovules per carpel). The new species also differs from M. fordiana by its branches (glabrous except the young nodes that are sparsely pubescent with erect brown trichomes vs. an indument of appressed, rusty brown trichomes), the peduncles, abaxial surfaces of leaves, and bottoms of outer tepals (glabrous vs. appressed, rusty brown trichomes), the petioles (sparsely brown pubescent and later glabrate vs. appressed, rusty brown trichomes), fewer ovules (six to eight vs. eight to 14 ovules per carpel), as well as the longer stigmas and beaks (stigmas 4–5 mm vs. 1–2 mm, beaks 2–4 mm vs. 1–2 mm).

Nano Mg1−xNixAl2O4 spinel pigments for advanced applications

Nano Mg1−xNixAl2O4 spinel pigments were synthesized via polymeric combustion technique upon heat treatment at 210°C. Citric acid in the presence of ethylene glycol polymer, with mass ratio of 60:40, was successfully used as a host network for the synthesis process. The obtained spinel was calcined at different temperatures; 300–1200°C and investigated by thermal analysis (TG-DTG/DTA), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). UV–Vis and diffuse reflectance spectroscopy (DRS) using CIE-Lab/parameters methods have been used for color measurements. The addition of colored pigment on different types of glazes was studied. The results revealed that NiMgAl2O4 spinel beside MgNiO phases were crystallized with particle sizes of 9–21nm at 600°C and 52–180nm at 1200°C. All prepared samples exhibited green to pale green colors due to the inclusion of Ni2+ inside the spinel structure. The pale green color intensity increased with increasing calcination temperature. The prepared pigment was suitable to convert commercial and opaque glazes to color product to be used in different applications.

Nephrite Jade From Val Malenco, Italy: Review and Update

Alpe Mastabia, in the Val Malenco district of northern Italy, has been a source of nephrite jade since the early 2000s. Twenty-one samples from this locality were investigated by classical gemological methods; X-ray powder diffraction, combined with quantitative phase analysis; scanning electron microscopy in combination with energy-dispersive spectrometry; electron microprobe analysis; mass spectrometry; and mid-infrared spectroscopy. From a mineralogical standpoint, this jade consists mainly of tremolite amphibole, with variable amounts of other constituents, especially calcite (up to approximately 30 wt.%), but also pyroxene, apatite, and sulfide minerals. Its pale green color is related to the low iron content of the tremolite amphibole, whereas the other minerals are responsible for different colors (cal cite for white, molybdenite and galena for gray). On the basis of minor and trace-element composition, we can classify this jade as dolomite-related nephrite (para-nephrite). Although new material could be recovered from this area, future production will probably be limited by access difficulties.

Growth and Nutrient Content of Hybrid Bermudagrass Grown for Nursery Purposes at Different Nitrogen, Phosphorus, and Potassium Rates

The objective of this research was to study the effect of different nitrogen (N), phosphorus (P), and potassium (K) rates on growth and nutrient content of hybrid bermudagrass (Cynodon dactylon × C. transvaalensis) grown in pots for nursery purposes (producing stolons to obtain one-node sprigs to be used as propagation material). Starting from control N, P, and K rates (314, 52, and 198 mg·L−1 substrate, respectively), each element was reduced to zero, halved, doubled, or tripled while the other two were kept unchanged (13 treatments in all). As expected, N, P, and K proved to be necessary for plant growth and development. In fact, when one element was not supplied, plants showed reduced growth and pale-green color. The dry weight of aerial part (shoots plus stolons) was mainly affected by N and increased along with this element with a nonlinear less than proportional trend. Phosphorus had a larger effect than N or K on the number of primary stolons, which varied along with P rate fitting a nonlinear regression model. Potassium rate influenced the characteristics of primary stolons (length, number of nodes, and ramifications) more than N or P. A significant linear regression was observed for the number of ramifications (secondary stolons), while stolon length and the number of nodes fit a nonlinear regression model. Plant growth response to the imposed rates revealed the possibility to halve N or P in respect to control rates, while for K the control rate proved to be necessary. In fact, when K rate was halved, the number of nodes, which is a main parameter for nursery purposes, significantly decreased. Half N, half P, and control K rates also ensured a satisfactory plant mineral composition, consistent with values previously reported for bermudagrass. Potassium competition with both calcium and magnesium was observed. Nitrogen, P, or K rates higher than the respective controls are not advisable since they did not enhance plant growth or mineral content.

Reversibility of electrosurface transfer through eutectic interfaces of MeWO4|WO3 (Me − Ca, Sr, Ba)

It is found that electrosurface transition (EST) through eutectic interfaces of (−/+)WO3|MeWO4(+/−) induced by electric field is a reversible process. In the case of the (−/+) polarity, nominally, in the “direct experiment”, macro amounts of WO3 from a W3(−) brick are drawn in the (+) direction onto the inner surface of MeWO4 forming a two-phase {ie1070-1} composite. Simultaneously, nonequivalent countertransport of Me2+ within the W3(−) brick occurs, which changes the color of W3(−) from the natural hue to dark-green. Intercalation of Me2+ into W3(−) is proved by several spectroscopic methods. The key role in the EST phenomenon belongs to a nonautonomous electrolytic phase of MeW-s formed on the contact interface with WO3|MeWO4. The composition of MeW-s is close to W/Me ≈ 2. As a result of EST, the cell acquires a more complicated structure: {fx1070-1} where |///| are interface regions occupied by the MeW-s phase. At the cathodic boundary of subcell {fx1070-2} the following process occurs: {fx1070-3}, The process at the anodic boundary is: {fx1070-4}. Ultimately, WO3 is transported in the (+) direction (into the composite) and Me2+ penetrates under the effect of the gradient in chemical potential into W3(−) forming a dark-green MexWO3 phase with its front reaching the (−) Pt electrode. After the end of the “direct experiment”, the cell polarity was changed to (+/−) and the “reverse experiment” was carried out. Now, on the cathodic boundary |4 of subcell {fx1070-5} anions (WO4)2− are generated that are discharged on boundary 3| to oxide WO3 that is intercalated into the right boundary of MeWO4 − (3), where the rightmost composite region {ie1070-2} is formed. Thus, the mass of W3(−) decreases; it becomes dark-green (see above) and the mass of the MeWO4 disk continues growing and now its structure is as follows {ie1070-3}. It is important that the left W3(+) disk that was dark-green after the “direct experiment” gradually becomes lighter in the “reverse experiment” up to its natural pale green color, i.e., Me2+ is deintercalated from it: Me2+: MexWO3 + 1/2O2 → xMe2+ + 2e + WO3. It is found that dependences of variations of disk masses Δm(Q) practically coincide for the “direct” and “reverse” experiments.

Optimization of quality in exported <i>Polyscias balfouriana</i> "Marginata" by using different shade levels

Foliage plant industry in Sri Lanka often has to face difficulties due to problems associated with the qualities of the final product of plant especially, pale green colour leaves and poor quality shoots, which are not accept by the buyers in export market. An investigation was carried out to develop the green colour and other qualities of Polyscias balfouriana “Marginata” (PBM) using different shade levels within 10 weeks. Canes, 10 cm long were used as planting materials and planted in coir beds under, 55, 60, 65, 70, 75, 80, 85, 90 and 95% shade levels. Other qualities evaluated for PBM were shoot length, leaf area, number of leaves per shoot. It was evident that the preferable forest green colour was achieved significantly (p = 0.001) at the highest shade levels of 85 and 90%. The leaf area of 14 cm2 and, sprout of 7 cm to 7.5 cm length also achieved at highest shade levels of 85% and 90%. Percentage of canes with 3 or more than 3 leaves per shoot was significantly higher than that of canes with less than 3 leaves at shade levels higher than the control. The higher percentage of acceptable canes with 3 or more than 3 leaves was found in shade level of 80%, 85% and 90 %. With these findings it can be concluded that the use of high shade levels such as 85% and 90% at foliage nurseries are favorable to obtain quality PBM plant for export market. DOI: http://dx.doi.org/10.4038/jas.v7i2.4403 The Journal of Agricultural Sciences, 2012, vol.7, no 2 58-65

Identification and Characterization of LHCB1 Co-Suppressed Line in Arabidopsis

To explore the function of light-harvesting complex protein (LHCP) in Arabidopsis growth and development, the Leclere and Bartel seed collection was screened. In this collection randomly cloned cDNAs are expressed under the CaMV35S promoter. A pale green line has been identified and characterized in more details. Analysis of the inserted cDNA in the pale green line showed it encodes LHCB1 proteins. The transcript level of LHCB1 in the selected line was less than that of the wild type (WT) Arabidopsis plant. Characterization of the LHCB1 co-suppressed line was achieved through its comparison with the WT plants when both were grown under normal irradiance. Then several measurements were performed such as: fresh and dry weight, chla, chlb, chla/b ratios and total chlorophyll content, soluble and insoluble sugar contents, total protein level, Hill reaction level and chlorophyll fluorescence. The LHCB1co-suppressed plants showed smaller leaf area with pale green coloration. Suppression of the LHCB1 gene significantly reduced fresh weight, chla, chlb content, total chlorophyll, and the rate of Hill reaction. Soluble and insoluble sugars, total protein, and chlorophyll fluorescence did not show significant differences between this line and WT plants. Meanwhile there was not any significant difference in fluorescence parameters between the WT and LHCB1 co-suppressed line.

The nonclimacteric guava cultivar ‘Jen-Ju Bar’ is defective in system 2 1-aminocyclopropane-1-carboxylate synthase activity

The ripening characteristics and physiology of two guava cultivars, ‘Jen-Ju Bar’ (‘JJB’) and ‘Li-Tzy Bar’ (‘LTB’), were investigated and compared because of their divergent storability. During storage at 20°C, mature-green ‘LTB’ fruit exhibited ripening behavior typical for a climacteric fruit, including increases in respiration and ethylene production (3.75mmolCO2kg−1h−1 and 1.37×103nmolC2H4kg−1h−1 at peak levels, respectively), yellow color development, flesh softening, and volatile production. By contrast, ‘JJB’ is considered a nonclimacteric fruit because it features low and stable rates of respiration (0.61–0.73mmolCO2kg−1h−1) and ethylene production (less than 4nmolC2H4kg−1h−1) while retaining its pale-green color and firmness throughout a 20d observation period. Furthermore, the nonclimacteric nature of ‘JJB’ fruit was revealed through its responses to various levels of applied ethylene, as its respiration rate increased in a concentration-dependent manner. This respiration enhancement occurred only when exogenous ethylene was present and could be evoked repeatedly in the same ‘JJB’ fruit. The ripening characteristics of ‘JJB’ do not result from a defect in ethylene signaling, but instead result from a lack of autocatalytic ethylene synthesis, as propylene ventilation stimulated normal fruit ripening and an upsurge of respiration without a massive endogenous ethylene release. However, a cutting treatment of ‘JJB’ was able to induce stress-responsive ethylene production expected from system 1 ethylene biosynthesis. The finding that 1-aminocyclopropane-1-carboxylic acid (ACC) content and ACC synthase (ACS) activity were significantly lower in ‘JJB’ than in ‘LTB’ fruit after harvest, together with the finding that treatment with ACC (rather than S-adenosyl-l-methionine) led to both fully ripened ‘JJB’ fruit and endogenous ethylene production, strongly suggest that insufficient ACC synthesis, i.e., the reaction catalyzed by ACS, prevents system 2 ethylene biosynthesis in ‘JJB’ guava fruit.

The effects of sulfur intercalation on the optical properties of artificial ‘hackmanite’, Na8[Al6Si6O24]Cl1.8S0.1; ‘sulfosodalite’, Na8[Al6Si6O24]S; and natural tugtupite, Na8[Be2Al2Si8O24](Cl,S)2−δ

The minerals ‘hackmanite’ and tugtupite exhibit tenebrescence (reversible photochromism) and photoluminescence. These features are generally attributed to the presence of sulfide species within their structures. But how these optical properties might be affected by intercalating additional amounts of sulfur into their structures was until now unknown. Artificial ‘hackmanite’, Na8[Al6Si6O24]Cl1.8S0.1, and ‘sulfosodalite’, Na8[Al6Si6O24]S, were heated with sulfur in evacuated quartz-glass ampoules over the temperature range 450–1,050°C. This work has shown that sulfur intercalation into Na8[Al6Si6O24]Cl1.8S0.1 destroys the tenebrescence and induces a permanently pale blue and, at higher temperature, a pale green coloration. The effect on Na8[Al6Si6O24]S induced similar colorations but of a deeper hue. Annealing tugtupite, Na8[Be2Al2Si8O24](Cl,S)2−δ under a sulfur atmosphere over the range 600–700°C, destroyed the tenebrescence and resulted in a colorless tugtupite; but did not effect the photoluminescence. This suggests that the chemical species responsible for the tenebrescence in tugtupite is unlikely to be the same as that for the luminescence.

CITRUS LEPROSIS IN FLORIDA, USA, APPEARS TO HAVE BEEN CAUSED BY THE NUCLEAR TYPE OF CITRUS LEPROSIS VIRUS (CiLV-N)

Citrus leprosis (CL) is a highly destructive viral disease vectored by Brevipalpus phoenicis Geijskes (Acari: Tenuipalpidae). It was first described in Florida in 1907 and last reported in 1968. CL was found after the 1920s in South America (Paraguay, Argentina and Brazil) and presently is known to occur in most of the South American countries. After its detection in Panama in 2000, the disease spread quickly northward through Central America and is now established in Southern Mexico, threatening all of the Caribbean islands as well as the citrus growing areas within the United States. The disappearance of the CL from the United States could be attributed to the severe freeze of December 1966. Multiple spray applications of sulphur for mite control could have gradually reduced the source of inoculum by substantially reducing the Brevipalpus populations. Recent ultrastructural studies revealed that CL may be caused by two distinct viruses, respectively the rare nuclear type (CiLV-N) and the prevalent cytoplasmic type (CiLV-C). A slight difference in foliar lesions caused by these viruses was noticed. CiLV-C produces leaf lesions that become larger in size, with a pale green color and commonly having gummy rings while CiLV-N induces smaller lesions with a dark center and a bright yellow halo. Analysis of available photographic records and samples in the Herbarium of the Instituto Biologico de Sao Paulo in Brazil strongly suggest that CL in Florida was caused by CiLV-N. This helps to explain the disappearance of CL from the United States because it is now known that CiLV-N is less aggressive than CiLV-C. DOI: http://dx.doi.org/10.17525/vrr.v16i1-2.51

Low-temperature-induced transcription factors in grapevine enhance cold tolerance in transgenic Arabidopsis plants

We report the characterization of low-temperature-induced transcription factors in grapevine ( Vitis vinifera). Four transcription factors were identified in low-temperature-treated grapevine. The expression of V. vinifera C-repeat-binding factors, VvCBF2, VvCBF4, and VvCBFL, and V. vinifera B-box-type zinc finger protein, VvZFPL, was immediately induced and upregulated in leaves by the low-temperature treatment. Similar induction of the gene expression was observed in low-temperature-treated stems and flowers, although VvZFPL was constitutively expressed in flowers. Tendrils expressed all the four genes constitutively. In berry skin, VvCBF2 and VvCBFL were induced by the low-temperature treatment before the onset of véraison, while only VvCBF2 was induced under the low-temperature condition after the onset of véraison. The overexpression of VvCBF2 and VvZFPL in Arabidopsis plants led to longer hypocotyls than the control plants. The rosette leaves of these plants were smaller and had lower chlorophyll contents than those of the control plants, resulting in a pale green color. Finally, the VvCBF2- and VvZFPL-overexpressing plants revealed growth retardation. These results suggest that VvCBF2 and VvZFPL may affect photomorphogenesis and growth in grapevine. Meanwhile, no morphological changes were detected in the VvCBF4- and VvCBFL-overexpressing plants. The cold tolerance test demonstrated that all of the overexpressing plants remained viable and noticeably healthy compared with the control plants even after exposure to severe cold treatment, suggesting that VvCBF2, VvCBF4, VvCBFL, or VvZFPL may enhance cold tolerance in grapevine.

LPA19, a Psb27 Homolog in Arabidopsis thaliana, Facilitates D1 Protein Precursor Processing during PSII Biogenesis

The biogenesis and assembly of photosystem II (PSII) are mainly regulated by the nuclear-encoded factors. To further identify the novel components involved in PSII biogenesis, we isolated and characterized a high chlorophyll fluorescence low psii accumulation19 (lpa19) mutant, which is defective in PSII biogenesis. LPA19 encodes a Psb27 homolog (At1g05385). Interestingly, another Psb27 homolog (At1g03600) in Arabidopsis was revealed to be required for the efficient repair of photodamaged PSII. These results suggest that the Psb27 homologs play distinct functions in PSII biogenesis and repair in Arabidopsis. Chloroplast protein labeling assays showed that the C-terminal processing of D1 in the lpa19 mutant was impaired. Protein overlay assays provided evidence that LPA19 interacts with D1, and coimmunoprecipitation analysis demonstrated that LPA19 interacts with mature D1 (mD1) and precursor D1 (pD1). Moreover, LPA19 protein was shown to specifically interact with the soluble C terminus present in the precursor and mature D1 through yeast two-hybrid analyses. Thus, these studies suggest that LPA19 is involved in facilitating the D1 precursor protein processing in Arabidopsis.

Cephalosporium maydis, the Cause of Late Wilt in Maize, a Pathogen New to Portugal and Spain.

Scattered maize (Zea mays L.) plants with symptoms of premature wilting were observed in two fields in Toledo (Spain) during the summer of 2003. In 2008, affected fields in Toledo and Ribatejo (Portugal) showed incidences as much as 60% and symptoms affecting 50% of the hybrid varieties. Wilting became visible before tasseling and continued until shortly before maturity. It steadily progressed from the lower to upper leaves; the leaf tissues between the veins changing first to a pale green color then the whole leaf rolling inward lengthwise. Some leaves dried up and became brittle. As leaf wilting advanced, yellowish or reddish brown streaks appeared on the basal internodes of the stalk, which dried up and became shrunken. When the stalk was split, a brown discoloration extended along the internodes. The fungus that was consistently isolated from necrotic roots and basal tissues of the stalks of plants from both locations was identified as Cephalosporium maydis Samra, Sabet & Hingorani (1). The internal transcribed spacer (ITS) region of mycelial DNA was amplified (ITS1 and ITS2 primers) and sequenced. BLAST analysis showed 99% homology with C. maydis (GenBank Accession Nos. CM2A1, CM884, CM3B, and CM1A). Pathogenicity was confirmed in a shadehouse experiment from March to July of 2009. One isolate from Ribatejo and another from Toledo were independently inoculated to 24 4-day-old seedlings of each of two maize varieties. The experimental unit consisted of six seedlings planted in an 8-liter pot filled with sand/silt previously infested with 200 g of wheat grains colonized by the fungi. Noncolonized wheat grains were used for the control treatments. Four replications (pots) were established for each genotype/isolate combination according to a complete randomized 2 × 3 factorial design. After 6 weeks, four plants in each pot were randomly selected for evaluation of root necrosis, plant height, and reisolations of C. maydis. The two remaining plants were grown for nine additional weeks, then their weights were determined, and the percentages of aboveground tissues that were prematurely necrotic and dry were evaluated. Six weeks after inoculation, percentage of root necrosis of inoculated plants ranged between 75 and 100%, which was significantly higher than those of the controls (0%). No significant differences of height were recorded. At the end of the experiment, 28 to 53% of aboveground tissues of inoculated plants were necrotic and dry, significantly higher than in the controls. Regardless of the variety, weights of the inoculated plants were significantly reduced to 45 and 65% of the control plants. When root and stalk tissues from both varieties were sampled and incubated on potato dextrose agar at 25°C, the mycelial growth of C. maydis was confirmed for the inoculated plants but not for the control plants: colonies with "rhizoid" appearance of the margin, first white in color and turning to ash gray with age. To our knowledge, this is the first report of the presence of C. maydis outside Egypt, Hungary, and India. This geographical expansion of the pathogen will eventually affect the maize breeding programs for southern Europe. Reference: (1) A. S. Samra et al. Phytopathology 53:402, 1963.

Mineralogical characteristics of unusual “Anatolian” diaspore (zultanite) crystals from the İlbirdağı diasporite deposit, Turkey

The İlbirdağı diasporic metabauxite (diasporite) deposit of the Milas (Muğla) region of Turkey is a unique deposit including both metamorphic (primary) and hydrothermal-remobilized (secondary) diaspore that formed during different geological periods. Microscopic diaspore crystals with a metamorphic origin are common and are the main constituent of the metabauxite ore, which was metamorphosed during from the Late Cretaceous to Late Paleocene Periods. However, secondary macroscopic diaspore crystals filling fracture zones that crosscut the metabauxite ore formed during the Late Paleocene, Eocene and Oligocene Periods as the result of later hydrothermal solutions that remobilized constituents of the metabauxite. The macroscopic diaspore crystals can be distinguished from the metamorphosed microscopic diaspore crystals, based on size, appearance, occurrence, and origin. Approximately 60% of the macroscopic diaspore crystals have an opaque appearance and pale green coloration and are not considered attractive. By contrast, the other 40% are gem quality and exhibit a marked change in color under different types of illumination. The crystals are mostly olive-green and soil-brown in daylight. A small number of the crystals display color-change, such as green in daylight or equivalent illumination and carmine in low-wattage tungsten lights. X-ray diffraction (XRD) study, using a comparative matching technique, reveals that these Anatolian diaspore (zultanite) crystals [AlO(OH)] are polycrystalline and that their X-ray spectrum includes the overlapped XRD peaks of some mineral inclusions consisting of donbassite [Al 5.33Si 3O 10(OH) 8] (di-di-octahedral sheeted Al-rich chlorite), corundum (Al 2O 3), boehmite [AlO(OH)], quartz (SiO 2), ilmenite (FeTiO 3), goethite [FeO(OH)] and chloritoid [(Fe, Mg, Mn) 2Al 4Si 2O 10(OH) 4]. We label these unusual inclusions as sub-microscopic inclusions, because they cannot be seen with a polarizing microscope. Polarizing microscope (PM), scanning electron microscope (SEM), optical absorption (OA), Fourier transform-infrared (FT-IR) and simultaneous differential-thermogravimetric analysis (DTA/TGA) investigations were performed to reveal the mineralogical characteristics of the Anatolian diaspore crystals.

Growth and characterization of ferroelectric Tb 2(MoO 4) 3 crystal

By using Tb 4O 7 and MoO 3 as starting materials, ferroelectric Tb 2(MoO 4) 3 crystal was grown by the Czochralski method. The as-grown crystal was pale green color, transparent and crack-free. X-ray powder diffraction (XRPD), transmission spectrum, dielectric constant and polarization-electric field ( P-E) hysteresis loop measurements were performed to characterize the crystal. The XRPD confirmed the as-grown crystal to be Tb 2(MoO 4) 3. The transmission spectrum of the crystal showed that its transmittance in the entire visible and most near-infrared region was more than 70% except for an absorption peak around 486 nm. Obvious dielectric anomaly could be observed at low frequencies with increasing temperature through the dielectric constant measurement and the Curie temperature of Tb 2(MoO 4) 3 crystal was determined to be 162.3 °C. The unsaturated P- E hysteresis loops indicated that it was difficult for the ferroelectric domains in Tb 2(MoO 4) 3 crystal to array regularly with repeated switching of the electric field.

The effect of the atmosphere on the optical properties of as-synthesized colloidal indium tinoxide

The optical properties of indium tin oxide (ITO) have often been explored when it is in theform of deposited thin films. In this study, a colloidal chemistry approach is taken toinvestigate the influence of the atmosphere on the optical properties of ITO nanoparticles.X-ray diffraction (XRD), transmission electron microscopy (TEM), absorption spectroscopyand photoluminescence (PL) were used to characterize colloidal ITO samples, synthesizedunder aerated and inert conditions, with the same composition. In both cases, theITO can be completely dispersed in a non-polar solvent without any evidenceof agglomeration. For the ITO made in air, the nanoparticle–solvent solutionexhibits a pale green color, and XRD and TEM indicate an average particle size of∼7 nm and small shrinkage in the lattice structure. When the ITO is synthesized under inertconditions, the solution turns blue, and XRD and TEM indicate an average particle size of∼8 nm and even less strain in the lattice than for the ITO synthesized under aeratedconditions. The change in color and lattice strain is attributed to the difference in oxygenvacancy concentration for the ITO nanoparticles synthesized under aerated and inertconditions, which exhibit different optical band gap values of 3.89 eV and 4.05 eV,respectively. Our work here shows that thin film deposition or sintering steps may not berequired for studying the optical properties of as-synthesized ITO nanoparticles.

Enhanced Polymer Grafting from Multiwalled Carbon Nanotubes through Living Anionic Surface-Initiated Polymerization

Anionic surface-initiated polymerization of ethylene oxide and styrene has been performed using multiwalled carbon nanotubes (MWNTs) functionalized with anionic initiators. The surface of MWNTs was modified via covalent attachment of precursor anions such as 4-hydroxyethyl benzocyclobutene (BCB-EO) and 1-benzocyclobutene-1′-phenylethylene (BCB-PE) through Diels−Alder cycloaddition at 235 °C. Surface-functionalized MWNTs-g-(BCB-EO)n and MWNTs-g-(BCB-PE)n with 23 and 54 wt % precursor initiators, respectively, were used for the polymerizations. Alkoxide anion on the surface of MWNTs-g-(BCB-EO)n was generated through reaction with potassium triphenylmethane for the polymerization of ethylene oxide in tetrahydrofuran and phenyl substituted alkyllithium was generated from the surface of MWNTs-g-(BCB-PE)n using sec-butyllithium for the polymerization of styrene in benzene. In both cases, the initiation was found to be very slow because of the heterogeneous reaction medium. However, the MWNTs gradually dispersed in the reaction medium during the polymerization. A pale green color was noticed in the case of ethylene oxide polymerization and the color of initiator as well as the propagating anions was not discernible visually in styrene polymerization. Polymer grafted nanocomposites, MWNTs-g-(BCB-PEO)n and MWNTs-g-(BCB-PS)n containing a very high percentage of hairy polymer with a small fraction of MWNTs (<1 wt %) were obtained. The conversion of ethylene oxide and the weight percent of PEO on the surface of the MWNTs increased with increasing reaction time indicating a controlled polymerization. The polymer-grafted MWNTs were characterized using FT-IR, 1H NMR, Raman spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and transmission electron microscopy (TEM). Size exclusion chromatography of the polymer grafted MWNTs revealed broad molecular weight distributions (1.3 < Mw/Mn < 1.8) indicating the presence of different sizes of polymer nanocomposites. The TEM images showed the presence of thick layers of polymer up to 30 nm around the MWNTs. The living nature of the growing polystyryllithium was used to produce diblock copolymer grafts using sequential polymerization of isoprene on the surface of MWNTs.

The lithium tolerance of the Arabidopsis cat2 mutant reveals a cross‐talk between oxidative stress and ethylene

In order to investigate the effects of a permanent increase in cellular H(2)O(2) on cation homeostasis we have studied a T-DNA insertion mutant of the Arabidopsis CATALASE 2 gene. This mutant (cat2-1) exhibits 20% of wild-type leaf catalase activity and accumulates more H(2)O(2) than the wild type under normal growth conditions. In addition to reduced size, a pale green color and great reduction in secondary roots, the cat2-1 mutant exhibited increased sensitivity to H(2)O(2), NaCl, norspermidine, high light and cold stress. On the other hand, the germination of the cat2-1 mutant is more tolerant to lithium than the wild type. This novel phenotype cannot be explained by changes in lithium transport. Actually, the uptake of lithium (and of other toxic cations such as sodium and norspermidine) is increased in the cat2-1 mutant while K(+) levels were decreased. The lithium tolerance of this mutant seems to result both from insensitivity to the inhibitory ethylene induced by this cation and a reduced capability for ethylene production. Accordingly, induction by ethylene of responsive genes such as PR4 and EBP/ERF72 is decreased in cat2-1. Mutants insensitive to ethylene such as etr1-1 and ein3-3 are lithium tolerant, and inhibition of ethylene biosynthesis with 2-aminoisobutyrate protects against lithium toxicity. Microarray analysis of gene expression indicates that the expression of genes related to cation transport and ethylene synthesis and perception was not altered in the cat2-1 mutant, suggesting that H(2)O(2) modulates these processes at the protein level. These results uncover a cross-talk between oxidative stress, cation homeostasis and ethylene.

A NEW SPECIES OF HYPSIBOAS (AMPHIBIA; ANURA; HYLIDAE) FROM THE VENEZUELAN GUAYANA, WITH NOTES ON HYPSIBOAS SIBLESZI (RIVERO 1972)

We describe a new species of Hypsiboas from the slopes and summit of Auyan-tepui in Canaima National Park, Bolivar State, Venezuela. The new species resembles H. sibleszi, but it differs from that species in having pale green dorsal coloration with numerous small chromatophores, dorsolateral white stripes that extend from the tip of snout to the groin when present, pale interorbital bar absent, a transparent yellow venter, yellow-colored digits and webbing, a more extensive webbing on hands and feet, a prepollical spine not protunding, very narrow nasals partially fused with sphenethmoid, a moderate-sized frontoparietal fontanelle, and an advertisement call consisting of three or four notes with a dominant frequency between 3010 and 3488 Hz. New data on the vocalization, osteology and distribution of H. sibleszi are provided.

β-Carotene accumulation induced by the cauliflower Or gene is not due to an increased capacity of biosynthesis

The cauliflower ( Brassica oleracea L. var. botrytis) Or gene is a rare carotenoid gene mutation that confers a high level of β-carotene accumulation in various tissues of the plant, turning them orange. To investigate the biochemical basis of Or-induced carotenogenesis, we examined the carotenoid biosynthesis by evaluating phytoene accumulation in the presence of norflurazon, an effective inhibitor of phytoene desaturase. Calli were generated from young seedlings of wild type and Or mutant plants. While the calli derived from wild type seedlings showed a pale green color, the calli derived from Or seedlings exhibited intense orange color, showing the Or mutant phenotype. Concomitantly, the Or calli accumulated significantly more carotenoids than the wild type controls. Upon treatment with norflurazon, both the wild type and Or calli synthesized significant amounts of phytoene. The phytoene accumulated at comparable levels and no major differences in carotenogenic gene expression were observed between the wild type and Or calli. These results suggest that Or-induced β-carotene accumulation does not result from an increased capacity of carotenoid biosynthesis.