Carbon components in the phosphoric acid fuel cell-an overview

International Nuclear Information System (INIS)

Appleby, J.

1983-01-01

The single breakthrough that has made the phosphoric acid fuel cell a practical reality has been the use of carbon or graphite components for the repeat parts of the cell stack. While the thermodynamic stability of carbon is such that rapid corrosion would be expected at the cathode at fuel cell operating temperature, its kinetic stability is remarkable despite the absence of passivating layers analogous to those on, for example, the Group VA elements niobium and tantalum. This happy accident, combined with the adequate electronic conductivity of the carbon materials used, has provided the opportunity to reduce fuel cell cost to attractive levels. The development of these carbon compounds is reviewed

Spectral evidence for multi-pathway contribution to the upconversion pathway in NaYF4:Yb3+,Er3+ phosphors.

Science.gov (United States)

Cho, Youngho; Song, Si Won; Lim, Soo Yeong; Kim, Jae Hun; Park, Chan Ryang; Kim, Hyung Min

2017-03-08

Although upconversion phosphors have been widely used in nanomedicine, laser engineering, bioimaging, and solar cell technology, the upconversion luminescence mechanism of the phosphors has been fiercely debated. A comprehensive understanding of upconversion photophysics has been significantly impeded because the number of photons incorporated in the process in different competitive pathways could not be resolved. Few convincing results to estimate the contribution of each of the two-, three-, and four-photon channels of near-infrared (NIR) energy have been reported in yielding upconverted visible luminescence. In this study, we present the energy upconversion process occurring in NaYF 4 :Yb 3+ ,Er 3+ phosphors as a function of excitation frequency and power density. We investigated the upconversion mechanism of lanthanide phosphors by comparing UV/VIS one-photon excitation spectra and NIR multi-photon spectra. A detailed analysis of minor transitions in one-photon spectra and luminescence decay enables us to assign electronic origins of individual bands in multi-photon upconversion luminescence and provides characteristic transitions representing the corresponding upconversion channel. Furthermore, we estimated the quantitative contribution of multiple channels with respect to irradiation power and excitation energy.

Probing the structure of glucan lyases – the lytic members of GH31 - by sequence analysis, circular dichroism and proteolysis

DEFF Research Database (Denmark)

Ernst, Heidi; Lo Leggio, Leila; Yu, Shukun

2005-01-01

Glucan lyase (GL) is a polysaccharide lyase with unique characteristics. It is involved in an alternative pathway for the degradation of alpha-glucans, the anhydrofructose pathway. Sequence similarity suggests that this lytic enzyme belongs to glycoside hydrolase family 31, for which until very r...

Structure-based functional annotation of putative conserved proteins having lyase activity from Haemophilus influenzae.

Science.gov (United States)

Shahbaaz, Mohd; Ahmad, Faizan; Imtaiyaz Hassan, Md

2015-06-01

Haemophilus influenzae is a small pleomorphic Gram-negative bacteria which causes several chronic diseases, including bacteremia, meningitis, cellulitis, epiglottitis, septic arthritis, pneumonia, and empyema. Here we extensively analyzed the sequenced genome of H. influenzae strain Rd KW20 using protein family databases, protein structure prediction, pathways and genome context methods to assign a precise function to proteins whose functions are unknown. These proteins are termed as hypothetical proteins (HPs), for which no experimental information is available. Function prediction of these proteins would surely be supportive to precisely understand the biochemical pathways and mechanism of pathogenesis of Haemophilus influenzae. During the extensive analysis of H. influenzae genome, we found the presence of eight HPs showing lyase activity. Subsequently, we modeled and analyzed three-dimensional structure of all these HPs to determine their functions more precisely. We found these HPs possess cystathionine-β-synthase, cyclase, carboxymuconolactone decarboxylase, pseudouridine synthase A and C, D-tagatose-1,6-bisphosphate aldolase and aminodeoxychorismate lyase-like features, indicating their corresponding functions in the H. influenzae. Lyases are actively involved in the regulation of biosynthesis of various hormones, metabolic pathways, signal transduction, and DNA repair. Lyases are also considered as a key player for various biological processes. These enzymes are critically essential for the survival and pathogenesis of H. influenzae and, therefore, these enzymes may be considered as a potential target for structure-based rational drug design. Our structure-function relationship analysis will be useful to search and design potential lead molecules based on the structure of these lyases, for drug design and discovery.

Les teneurs en carbone, azote et phosphore du sol sur l'occurrence ...

African Journals Online (AJOL)

Les teneurs en carbone, azote et phosphore du sol sur l'occurrence de Lippia multiflora M. (théier de savane) et la composition chimique de son huile essentielle extraite des feuilles au Nord-Ouest de la Côte d'Ivoire.

Production of activated carbon from peanut hill using phosphoric acid and microwave activation

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Weerawat Clowutimon

2015-06-01

Full Text Available The optimum conditions for preparing activated carbon from peanut hulls by phosphoric acid and microwave activation were studied. Factors investigated in this study were temperature of carbonization at 300, 350, 400 and 450๐ C, and time of carbonization at 30, 60 and 90 minutes. The optimum yield was observed that carbonization temperature of 400๐ C and time at 60 minutes, respectively. The yield of charcoal was 39% and the f ix carbon was 69%. Then the charcoal was activated by phosphoric acid and microwave irradiation, respectively. The effect of the weight per volume ratios of charcoal to activating acid (1:1, 1:2 and 2:1(W/V, microwave power at (activated 300, 500 and 700 watts, and activated time (30, 60 and 90 seconds were studied. The results showed that the optimum conditions for activating peanut charcoal were 1:2 (W/V charcoal per activating acid, microwave power 700 watts for 90 seconds. The results yielding maximum surface area by BET method was 303.1 m2 /g and pore volume was 0.140 cm3 /g. An efficiency of maximum iodine adsorption was 418 mg iodine/g activated carbon. Comparing the adsorption efficiency of non- irradiated and irradiated activated carbon, the efficiency of irradiated activated carbon improved up to 31%, due to its larger surface area and pore volume.

Red carbon dots-based phosphors for white light-emitting diodes with color rendering index of 92.

Science.gov (United States)

Zhai, Yuechen; Wang, Yi; Li, Di; Zhou, Ding; Jing, Pengtao; Shen, Dezhen; Qu, Songnan

2018-05-29

Exploration of solid-state efficient red emissive carbon dots (CDs) phosphors is strongly desired for the development of high performance CDs-based white light-emitting diodes (WLEDs). In this work, enhanced red emissive CDs-based phosphors with photoluminescence quantum yields (PLQYs) of 25% were prepared by embedding red emissive CDs (PLQYs of 23%) into polyvinyl pyrrolidone (PVP). Because of the protection of PVP, the phosphors could preserve strong luminescence under long-term UV excitation or being mixed with conventional packaging materials. By applying the red emissive phosphors as the color conversion layer, WLEDs with high color rendering index of 92 and color coordinate of (0.33, 0.33) are fabricated. Copyright © 2018 Elsevier Inc. All rights reserved.

Phenylalanine ammonia-lyase (PAL) gene activity in response to ...

African Journals Online (AJOL)

Phenylalanine ammonia-lyase (PAL) catalyzes the biosynthesis of rosmarinic acid (RA), tyrosine and phenylalanine are the precursors of RA, while proline drives metabolite precursors toward Shikimate and phenylpropanoid pathway ending with the production of RA. The aim of this study was to investigate the PAL gene ...

Utilization of Aspergillus oryzae to produce pectin lyase from various agro-industrial residues

Directory of Open Access Journals (Sweden)

Safia Koser

2014-07-01

Full Text Available The present study was aimed to investigate the culture influence on pectin lyase production potential of fungal strain Aspergillus oryzae. The enzyme profile of A. oryzae showed highest activity of pectin lyase after 3rd day of incubation on lemon peel waste under solid state fermentation conditions. To induce the pectin lyase synthesis capability of A. oryzae at optimal level various culture variables including physical and nutritional parameters were optimized by adopting classical optimization technique. Therefore, through fermentation process optimization the production of pectin lyase was substantially induced up to the level of 875 U/mL, when fermentation medium of lemon peel waste inoculated with 5 mL spore suspension of A. oryzae. The optimal fermentation conditions for maximum pectin lyase yield were as: optimum pH 5, 70% moisture level and incubated at 40 °C in addition with 1% sterile glucose solution as readily available carbon source and 0.2% yeast extract as an inexpensive nitrogen supplement (1%. The results obtained in current investigation so far demonstrated that culture conditions have great influence on the pectin lyase production potential of A. oryzae.

Characterization of two bacterial hydroxynitrile lyases with high similarity to cupin superfamily proteins

NARCIS (Netherlands)

Hussain, Z.; Wiedner, R.; Steiner, K.; Hajek, T.; Avi, M.; Hecher, B.; Sessitsch, A.; Schwab, H.

2012-01-01

Hydroxynitrile lyases (HNLs) catalyze the cleavage of cyanohydrins. In the reverse reaction, they catalyze the formation of carbon-carbon bonds by enantioselective condensation of hydrocyanic acid with carbonyls. In this study, we describe two proteins from endophytic bacteria that display activity

Chondroitin Sulfate (CS) Lyases: Structure, Function and Application in Therapeutics.

Science.gov (United States)

Rani, Aruna; Patel, Seema; Goyal, Arun

2018-01-01

Glycosaminoglycans (GAGs) such as chondroitin sulfate (CS) are the chief natural polysaccharides which reside in biological tissues mainly in extracellular matrix. These CS along with adhesion molecules and growth factors are involved in central nervous system (CNS) development, cell progression and pathogenesis. The chondroitin lyases are the enzyme that degrade and alter the CS chains and hence modify various signalling pathways involving CS chains. These CS lyases are substrate specific, can precisely manipulate the CS polysaccharides and have various biotechnological, medical and therapeutic applications. These enzymes can be used to produce the unsaturated oligosaccharides, which have immune-modulatory, anti-inflammatory and neuroprotective properties. This review focuses on the major breakthrough of the chondroitin sulfate degrading enzymes, their structures and functioning mechanism. This also provides comprehensive information regarding production, purification, characterization of CS lyases and their major applications, both established as well as emerging ones such as neural development. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Hydrogen sulfide (H2S)/cystathionine γ-lyase (CSE) pathway contributes to the proliferation of hepatoma cells

International Nuclear Information System (INIS)

Pan, Yan; Ye, Shuang; Yuan, Dexiao; Zhang, Jianghong; Bai, Yang; Shao, Chunlin

2014-01-01

Highlights: • Inhibition of H 2 S/CSE pathway strongly stimulates cellular apoptosis. • Inhibition of H 2 S/CSE pathway suppresses cell growth by blocking EGFR pathway. • H 2 S/CSE pathway is critical for maintaining the proliferation of hepatoma cells. - Abstract: Hydrogen sulfide (H 2 S)/cystathionine γ-lyase (CSE) pathway has been demonstrated to play vital roles in physiology and pathophysiology. However, its role in tumor cell proliferation remains largely unclear. Here we found that CSE over-expressed in hepatoma HepG2 and PLC/PRF/5 cells. Inhibition of endogenous H 2 S/CSE pathway drastically decreased the proliferation of HepG2 and PLC/PRF/5 cells, and it also enhanced ROS production and mitochondrial disruption, pronounced DNA damage and increased apoptosis. Moreover, this increase of apoptosis was associated with the activation of p53 and p21 accompanied by a decreased ratio of Bcl-2/Bax and up-regulation of phosphorylated c-Jun N-terminal kinase (JNK) and caspase-3 activity. In addition, the negative regulation of cell proliferation by inhibition of H 2 S/CSE system correlated with the blockage of cell mitogenic and survival signal transduction of epidermal growth factor receptor (EGFR) via down-regulating the extracellular-signal-regulated kinase 1/2 (ERK1/2) activation. These results demonstrate that H 2 S/CSE and its downstream pathway contribute to the proliferation of hepatoma cells, and inhibition of this pathway strongly suppress the excessive growth of hepatoma cells by stimulating mitochondrial apoptosis and suppressing cell growth signal transduction

Pathway confirmation and flux analysis of central metabolic pathways in Desulfovibrio vulgaris Hildenborough using gas chromatography-mass spectrometry and fourier transform-ion cyclotron resonance mass spectrometry

International Nuclear Information System (INIS)

Tang, Yinjie; Pingitore, Francesco; Mukhopadhyay, Aindrila; Phan, Richard; Hazen, Terry C.; Keasling, Jay D.

2006-01-01

It has been proposed that during growth under anaerobic or oxygen-limited conditions Shewanella oneidensis MR-1 uses the serine-isocitrate lyase pathway common to many methylotrophic anaerobes, in which formaldehyde produced from pyruvate is condensed with glycine to form serine. The serine is then transformed through hydroxypyruvate and glycerate to enter central metabolism at phosphoglycerate. To examine its use of the serine-isocitrate lyase pathway under anaerobic conditions, we grew S. oneidensis MR-1 on [1-13C] lactate as the sole carbon source with either trimethylamine N-oxide (TMAO) or fumarate as an electron acceptor. Analysis of cellular metabolites indicates that a large percentage (>75 percent) of lactate was partially oxidized to either acetate or pyruvate. The 13C isotope distributions in amino acids and other key metabolites indicate that, under anaerobic conditions, a complete serine pathway is not present, and lactate is oxidized via a highly reversible serine degradation pathway. The labeling data also suggest significant activity in the anaplerotic (malic enzyme and phosphoenolpyruvatecarboxylase) and glyoxylate shunt (isocitrate lyase and malate synthase) reactions. Although the tricarboxylic acid (TCA) cycle is often observed to be incomplete in many other anaerobes (absence of 2-oxoglutaratede hydrogenase activity), isotopic labeling supports the existence of a complete TCA cycle in S. oneidensis MR-1 under TMAO reduction condition

Utilization of glyphosate as phosphate source: biochemistry and genetics of bacterial carbon-phosphorous lyase

DEFF Research Database (Denmark)

Hove-Jensen, Bjarne; Zechel, David L; Jochimsen, Bjarne

2014-01-01

After several decades of use of glyphosate, the active ingredient in weed killers such as Roundup, in fields, forests, and gardens, the biochemical pathway of transformation of glyphosate phosphorus to a useful phosphorus source for microorganisms has been disclosed. Glyphosate is a member of a l...

Synthesis and carbonization chemistry of a phosphorous-nitrogen based intumescent flame retardant

Energy Technology Data Exchange (ETDEWEB)

Ma, Haiyun, E-mail: mahaiyun@gmail.com [College of Chemistry and Environmental Science, HeBei University, Baoding, Hebei Province 071002 (China); Fang, Zhengping [MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Institute of Polymer Composites, Zhejiang University, Hangzhou 310027 (China); Laboratory of Polymer Materials and Engineering, Ningbo Institute of Technology, Zhejiang University, Ningbo 315100 (China)

2012-09-10

Graphical abstract: The carbonization chemistry and mechanism of a novel synthesized intumescent flame retardant. The final chars showed a complex P-O-Ph and aromatic/graphitic structure containing architecture. Highlights: Black-Right-Pointing-Pointer The IFR synthesized is polymeric and has high molecular weight. Black-Right-Pointing-Pointer The IFR has a higher thermal stability than most of the commercial IFRs. Black-Right-Pointing-Pointer The final chars of IFR showed a complex P-O-Ph and aromatic/graphitic structure. - Abstract: In this work, a polymeric phosphorous-nitrogen containing intumescent flame retardant, named poly(diaminodiphenyl methane spirocyclic pentaerythritol bisphosphonate) (PDSPB), was synthesized. The carbonization chemistry was investigated. FTIR and {sup 1}H NMR were used to confirm the chemical structure of PDSPB. Thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), in situ FTIR and energy dispersive X-ray (EDX) were used to investigate and monitor the chemical structural changes during thermal degradation. PDSPB demonstrated a three-step degradation behavior. PDSPB oligomers continuously polymerized and generated a higher macromolecular weight during the first step (200-250 Degree-Sign C). The phosphate ester bonds were broken down and phosphoric acid was released which dehydrated the carbon source to form chars during the second step (280-320 Degree-Sign C). The residues will be further degraded and form final chars during the final weight loss step (400-450 Degree-Sign C). The final chars showed a complex P-O-Ph and aromatic/graphitic structure containing architecture.

Luminescence behaviors of Eu- and Dy-codoped alkaline earth metal aluminate phosphors through potassium carbonate coprecipitation

Energy Technology Data Exchange (ETDEWEB)

Liang, Chen-Jui, E-mail: cjliang@fcu.edu.tw; Siao, Hao-Yi

2016-07-01

An electronic energy mechanism of activator and sensitizer was established to describe the luminescence behaviors of Eu- and Dy-codoped M(II)Al{sub 2}O{sub 4} (M(II) = Ba, Sr, Ca, Mg) phosphors through potassium carbonate coprecipitation. Experimental results demonstrated that the prepared phosphors exhibited superior crystallinity at a temperature lower than 950 °C. The phosphors are ordered according to emission intensity as follows Ca- > Ba- > Sr- > Mg-containing phosphors. The energy level for Eu{sup 2+} 4f{sup 6}5d{sup 1} → 4f{sup 7}, Eu{sup 3+4}D{sub 0} → {sup 7}F, and Dy{sup 3+4}F{sub 9/2} → {sup 6}H transitions and the effects of nephelauxetic and crystal field in Ba-, Sr-, and Ca-containing phosphors were discussed. The energy gap, (hv){sub em}, between 5d and 4f of Eu{sup 2+} ion is strongly affected by host composition, crystal field strength, and nephelauxetic effect. The infrared emission of 4f{sub 9/2} → 6h for Dy{sup 3+} is merely depend on the transfer of energy from Eu{sup 2+} upon excited. Ca-containing phosphor with maximum (hv){sub em} is attributed to the lowest bond length of Ca−O and highest ionization potential of Ca{sup 2+} ion, which leads to the effects of crystal field and nephelauxetic greater than that in the other phosphors. - Highlights: • The list of the collected figure captions: • Develop a new coprecipitation method to prepare high efficiency phosphors. • Obtain superior crystallinity with lower calcination temperature. • Luminescence behavior of Eu- and Dy-codoped on aluminate phosphors is discussed. • Investigate the effects of alkaline earth metal containing on crystal field and nephelauxetic.

Hydrogen sulfide (H{sub 2}S)/cystathionine γ-lyase (CSE) pathway contributes to the proliferation of hepatoma cells

Energy Technology Data Exchange (ETDEWEB)

Pan, Yan; Ye, Shuang; Yuan, Dexiao; Zhang, Jianghong; Bai, Yang; Shao, Chunlin, E-mail: clshao@shmu.edu.cn

2014-05-15

Highlights: • Inhibition of H{sub 2}S/CSE pathway strongly stimulates cellular apoptosis. • Inhibition of H{sub 2}S/CSE pathway suppresses cell growth by blocking EGFR pathway. • H{sub 2}S/CSE pathway is critical for maintaining the proliferation of hepatoma cells. - Abstract: Hydrogen sulfide (H{sub 2}S)/cystathionine γ-lyase (CSE) pathway has been demonstrated to play vital roles in physiology and pathophysiology. However, its role in tumor cell proliferation remains largely unclear. Here we found that CSE over-expressed in hepatoma HepG2 and PLC/PRF/5 cells. Inhibition of endogenous H{sub 2}S/CSE pathway drastically decreased the proliferation of HepG2 and PLC/PRF/5 cells, and it also enhanced ROS production and mitochondrial disruption, pronounced DNA damage and increased apoptosis. Moreover, this increase of apoptosis was associated with the activation of p53 and p21 accompanied by a decreased ratio of Bcl-2/Bax and up-regulation of phosphorylated c-Jun N-terminal kinase (JNK) and caspase-3 activity. In addition, the negative regulation of cell proliferation by inhibition of H{sub 2}S/CSE system correlated with the blockage of cell mitogenic and survival signal transduction of epidermal growth factor receptor (EGFR) via down-regulating the extracellular-signal-regulated kinase 1/2 (ERK1/2) activation. These results demonstrate that H{sub 2}S/CSE and its downstream pathway contribute to the proliferation of hepatoma cells, and inhibition of this pathway strongly suppress the excessive growth of hepatoma cells by stimulating mitochondrial apoptosis and suppressing cell growth signal transduction.

Studies on organic carbon, nitrogen and phosphorous in the sediments of Mandovi Estuary, Goa

Digital Repository Service at National Institute of Oceanography (India)

Nasnolkar, C.M.; Shirodkar, P.V.; Singbal, S.Y.S.

indicated a significant linear variation with clay and silt. The organic carbon varies from 1.04 to 32.77 mg.g sup(-1) and the total nitrogen and total phosphorous varies from 3.81 to 32.71 mg.g sup(-1) and from 0.46 to 6.74 mg.g sup(-1) respectively. A...

Structure of PhnP: a phosphodiesterase of the carbon-phosphorous lyase pathway for phosphonate degradation

DEFF Research Database (Denmark)

Podzelinska, Kateryna; He, Shu-Mei; Wathier, Matthew

2009-01-01

-dependent hydrolase of the ß-lactamase superfamily. Screening with a wide array of hydrolytically sensitive substrates indicated that PhnP is an enzyme with phosphodiesterase activity, having the greatest specificity toward bis(p-nitrophenyl)phosphate and 2',3'-cyclic nucleotides. No activity was observed toward RNA...

Improvement of Lighting Uniformity and Phosphor Life in Field Emission Lamps Using Carbon Nanocoils

Directory of Open Access Journals (Sweden)

Kun-Ju Chung

2015-01-01

Full Text Available The lighting performances and phosphor degradation in field emission lamps (FELs with two different kinds of cathode materials—multiwalled carbon nanotubes (MWCNTs and carbon nanocoils (CNCs—were compared. The MWCNTs and CNCs were selectively synthesized on 304 stainless steel wire substrates dip-coated with nanosized Pd catalysts by controlling the growth temperature in thermal chemical vapor deposition, and the film uniformity can be optimized by adjusting the growth time. FELs were successfully fabricated by assembling these cathode filaments with a glass bulb-type anode. The FEL with the CNC cathode showed much higher lighting uniformity and light-spot density and a lower current at the same voltage than that with the MWCNT cathode filament, and its best luminous efficiency was as high as 75 lm/W at 8 kV. We also found that, for P22, the phosphor degradation can be effectively suppressed by replacing MWCNTs with CNCs in the cathode, due to the much larger total bright spot area and hence much lower current density loading on the anode.

Transition of Emission Colours as a Consequence of Heat-Treatment of Carbon Coated Ce3+-Doped YAG Phosphors

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Liang-Jun Yin

2017-10-01

Full Text Available To modify the luminescence properties of Ce3+-doped Y3Al5O12 (YAG phosphors, they have been coated with a carbon layer by chemical vapor deposition and subsequently heat-treated at high temperature under N2 atmosphere. Luminescence of the carbon coated YAG:Ce3+ phosphors has been investigated as a function of heat-treatment at 1500 and 1650 °C. The 540 nm emission intensity of C@YAG:Ce3+ is the highest when heated at 1650 °C, while a blue emission at 400–420 nm is observed when heated at 1500 °C but not at 1650 °C. It is verified by X-ray diffraction (XRD that the intriguing luminescence changes are induced by the formation of new phases in C@YAG:Ce3+-1500 °C, which disappear in C@YAG:Ce3+-1650 °C. In order to understand the mechanisms responsible for the enhancement of YAG:Ce3+ emission and the presence of the blue emission observed for C@YAG:Ce3+-1500 °C, the samples have been investigated by a combination of several electron microscopy techniques, such as HRTEM, SEM-CL, and SEM-EDS. This local and cross-sectional analysis clearly reveals a gradual transformation of phase and morphology in heated C@YAG:Ce3+ phosphors, which is related to a reaction between C and YAG:Ce3+ in N2 atmosphere. Through reaction between the carbon layer and YAG host materials, the emission colour of the phosphors can be modified from yellow, white, and then back to yellow under UV excitation as a function of heat-treatment in N2 atmosphere.

Transition of Emission Colours as a Consequence of Heat-Treatment of Carbon Coated Ce3+-Doped YAG Phosphors.

Science.gov (United States)

Yin, Liang-Jun; Dierre, Benjamin; Sekiguchi, Takashi; van Ommen, J Ruud; Hintzen, Hubertus T Bert; Cho, Yujin

2017-10-16

To modify the luminescence properties of Ce 3+ -doped Y₃Al₅O 12 (YAG) phosphors, they have been coated with a carbon layer by chemical vapor deposition and subsequently heat-treated at high temperature under N₂ atmosphere. Luminescence of the carbon coated YAG:Ce 3+ phosphors has been investigated as a function of heat-treatment at 1500 and 1650 °C. The 540 nm emission intensity of C@YAG:Ce 3+ is the highest when heated at 1650 °C, while a blue emission at 400-420 nm is observed when heated at 1500 °C but not at 1650 °C. It is verified by X-ray diffraction (XRD) that the intriguing luminescence changes are induced by the formation of new phases in C@YAG:Ce 3+ -1500 °C, which disappear in C@YAG:Ce 3+ -1650 °C. In order to understand the mechanisms responsible for the enhancement of YAG:Ce 3+ emission and the presence of the blue emission observed for C@YAG:Ce 3+ -1500 °C, the samples have been investigated by a combination of several electron microscopy techniques, such as HRTEM, SEM-CL, and SEM-EDS. This local and cross-sectional analysis clearly reveals a gradual transformation of phase and morphology in heated C@YAG:Ce 3+ phosphors, which is related to a reaction between C and YAG:Ce 3+ in N₂ atmosphere. Through reaction between the carbon layer and YAG host materials, the emission colour of the phosphors can be modified from yellow, white, and then back to yellow under UV excitation as a function of heat-treatment in N₂ atmosphere.

Perturbation of formate pathway for hydrogen production by expressions of formate hydrogen lyase and its transcriptional activator in wild Enterobacter aerogenes and its mutants

Energy Technology Data Exchange (ETDEWEB)

Lu, Yuan; Zhao, Hongxin; Zhang, Chong; Lai, Qiheng; Xing, Xin-Hui [Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084 (China)

2009-06-15

To examine perturbation effects of formate pathway on hydrogen productivity in Enterobacter aerogenes (Ea), formate dehydrogenase FDH-H gene (fdhF) and formate hydrogen lyase activator protein FHLA gene (fhlA) originated from Escherichia coli, were overexpressed in the wild strain Ea, its hycA-deleted mutant (A) by knockout the formate hydrogen lyase repressor and hybO-deleted mutant (O) by knockout of the uptake hydrogenase, respectively. Overexpression of fdhF and fhlA promoted cell growth and volumetric hydrogen production rates of all the strains, and the hydrogen production per gram cell dry weight (CDW) for Ea, A and O was increased by 38.5%, 21.8% and 5.25%, respectively. The fdhF and fhlA overexpression improved the hydrogen yield per mol glucose of strains Ea and A, but declined that of strain O. The increase of hydrogen yield of the strain Ea with fdhF and fhlA expression was mainly attributed to the increase of formate pathway, while for the mutant A, the improved hydrogen yield with fdhF and fhlA expression was mainly due to the increase of NADH pathway. Analysis of the metabolites and ratio of ethanol-to-acetate showed that the cellular redox state balance and energy level were also changed for these strains by fdhF and fhlA expression. These findings demonstrated that the hydrogen production was not only dependent on the hydrogenase genes, but was also affected by the regulation of the whole metabolism. Therefore, fdhF and fhlA expression in different strains of E. aerogenes could exhibit different perturbation effects on the metabolism and the hydrogen productivity. (author)

Electrocatalytic and supercapacitor performance of Phosphorous and Nitrogen co-doped Porous Carbons synthesized from Aminated Tannins

International Nuclear Information System (INIS)

Bairi, Venu Gopal; Nasini, Udaya B.; Kumar Ramasahayam, Sunil; Bourdo, Shawn E.; Viswanathan, Tito

2015-01-01

Highlights: • Microwave Synthetic technique using aminated tannins is reported for the first time. • P,N doped carbon was characterized extensively for physico-chemical properties. • Cyclic Voltammetry, RDE and RRDE studies were investigated for O 2 reduction capability. • O 2 reduction occurred by a kinetically favored one step four electron reduction pathway. • The charge storage capacity was found to be 161 F/g at 5 mV/S in alkaline conditions. - Abstract: A phosphorus and nitrogen co-doped carbon material (PNDC) was synthesized from aminated tannin and polyphosphoric acid by a rapid and highly efficient microwave synthetic technique. X-ray photoelectron spectroscopy study was useful in the identification of nitrogen and phosphorous environments in a sp 2 hybridized carbon lattice. The PNDC was found to be a porous material with a surface area of 433 m 2 g −1 . PNDC sample exhibited excellent thermal stability and the Raman spectroscopic studies were used for analyzing defects in the sp 2 hybridized carbon lattice. This material has promising electrochemical applications, especially for catalyzing oxygen reduction reaction in fuel cells and for charge storage in supercapacitors. The oxygen reduction capability of PNDC was investigated in 0.1 M KOH solution, and rotating disk and ring disk electrode studies were performed to identify the mechanism of oxygen reduction. The capacitative behavior of the PNDC was investigated in 6 M KOH and specific capacitance was determined to be 161 F g −1 due to the electric double layer charge storage phenomenon.

Mechanistic deductions from multiple kinetic and solvent deuterium isotope effects and pH studies of pyridoxal phosphate dependent carbon-carbon lyases: escherichia coli tryptophan indole-lyase

International Nuclear Information System (INIS)

Kiick, D.M.; Phillips, R.S.

1988-01-01

Analysis of the pH dependence of the kinetic parameters and competitive inhibitor Ki values for tryptophan indole-lyase suggests two enzymic groups must be unprotonated in order to facilitate binding and catalysis of tryptophan. The V/K for tryptophan and the pKi for oxindolyl-L-alanine, a putative transition state analogue and competitive inhibitor, decrease below two pK values of 7.6 and 6.0, while the Ki for L-alanine, also a competitive inhibitor, is 3300-fold larger (20 mM) than that for oxindolyl-L-alanine and increases below a single pK of 7.6. A single pK of 7.6 is also observed in the V/K profile for the alternate substrate, S-methyl-L-cysteine. Therefore, the enzymic group with a pK of 7.6 is responsible for proton abstraction at the 2-position of tryptophan, while the enzymic group with a pK of 6.0 interacts with the indole portion of tryptophan and probably catalyzes formation of the indolenine tautomer of tryptophan (in concert with proton transfer to C-3 of indole from the group with pK 7.6) to facilitate carbon-carbon bond cleavage and elimination of indole. The pH variation of the primary deuterium isotope effects for proton abstraction at the 2-position of tryptophan (DV = 2.5 and D(V/Ktrp) = 2.8) are pH independent, while the Vmax for tryptophan or S-methyl-L-cysteine is the same and also pH independent. Thus, substrates bind only to the correctly protonated form of the enzyme. Further, tryptophan is not sticky, and the pK values observed in both V/K profiles are the correct ones

Activation of the jasmonic acid pathway by depletion of the hydroperoxide lyase OsHPL3 reveals crosstalk between the HPL and AOS branches of the oxylipin pathway in rice.

Directory of Open Access Journals (Sweden)

Xiaoqiang Liu

Full Text Available The allene oxide synthase (AOS and hydroperoxide lyase (HPL branches of the oxylipin pathway, which underlie the production of jasmonates and aldehydes, respectively, function in plant responses to a range of stresses. Regulatory crosstalk has been proposed to exist between these two signaling branches; however, there is no direct evidence of this. Here, we identified and characterized a jasmonic acid (JA overproduction mutant, cea62, by screening a rice T-DNA insertion mutant library for lineages that constitutively express the AOS gene. Map-based cloning was used to identify the underlying gene as hydroperoxide lyase OsHPL3. HPL3 expression and the enzyme activity of its product, (E-2-hexenal, were depleted in the cea62 mutant, which resulted in the dramatic overproduction of JA, the activation of JA signaling, and the emergence of the lesion mimic phenotype. A time-course analysis of lesion formation and of the induction of defense responsive genes in the cea62 mutant revealed that the activation of JA biosynthesis and signaling in cea62 was regulated in a developmental manner, as was OsHPL3 activity in the wild-type plant. Microarray analysis showed that the JA-governed defense response was greatly activated in cea62 and this plant exhibited enhanced resistance to the T1 strain of the bacterial blight pathogen Xanthomonasoryzaepvoryzae (Xoo. The wounding response was attenuated in cea62 plants during the early stages of development, but partially recovered when JA levels were elevated during the later stages. In contrast, the wounding response was not altered during the different developmental stages of wild-type plants. These findings suggest that these two branches of the oxylipin pathway exhibit crosstalk with regards to biosynthesis and signaling and cooperate with each other to function in diverse stress responses.

Carbon footprint assessment of recycling technologies for rare earth elements: A case study of recycling yttrium and europium from phosphor.

Science.gov (United States)

Hu, Allen H; Kuo, Chien-Hung; Huang, Lance H; Su, Chao-Chin

2017-02-01

Rare earth elements are key raw materials in high-technology industries. Mining activities and manufacturing processes of such industries have caused considerable environmental impacts, such as soil erosion, vegetation destruction, and various forms of pollution. Sustaining the long-term supply of rare earth elements is difficult because of the global shortage of rare earth resources. The diminishing supply of rare earth elements has attracted considerable concern because many industrialized countries regarded such elements as important strategic resources for economic growth. This study aims to explore the carbon footprints of yttrium and europium recovery techniques from phosphor. Two extraction recovery methods, namely, acid extraction and solvent extraction, were selected for the analysis and comparison of carbon footprints. The two following functional units were used: (1) the same phosphor amounts for specific Y and Eu recovery concentrations, and (2) the same phosphor amounts for extraction. For acid extraction method, two acidic solutions (H 2 SO 4 and HCl) were used at two different temperatures (60 and 90°C). For solvent extraction method, acid leaching was performed followed by ionic liquid extraction. Carbon footprints from acid and solvent extraction methods were estimated to be 10.1 and 10.6kgCO 2 eq, respectively. Comparison of the carbon emissions of the two extraction methods shows that the solvent extraction method has significantly higher extraction efficiency, even though acid extraction method has a lower carbon footprint. These results may be used to develop strategies for life cycle management of rare earth resources to realize sustainable usage. Copyright © 2016 Elsevier Ltd. All rights reserved.

Sphingosine-1-Phosphate Lyase Deficient Cells as a Tool to Study Protein Lipid Interactions.

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Mathias J Gerl

Full Text Available Cell membranes contain hundreds to thousands of individual lipid species that are of structural importance but also specifically interact with proteins. Due to their highly controlled synthesis and role in signaling events sphingolipids are an intensely studied class of lipids. In order to investigate their metabolism and to study proteins interacting with sphingolipids, metabolic labeling based on photoactivatable sphingoid bases is the most straightforward approach. In order to monitor protein-lipid-crosslink products, sphingosine derivatives containing a reporter moiety, such as a radiolabel or a clickable group, are used. In normal cells, degradation of sphingoid bases via action of the checkpoint enzyme sphingosine-1-phosphate lyase occurs at position C2-C3 of the sphingoid base and channels the resulting hexadecenal into the glycerolipid biosynthesis pathway. In case the functionalized sphingosine looses the reporter moiety during its degradation, specificity towards sphingolipid labeling is maintained. In case degradation of a sphingosine derivative does not remove either the photoactivatable or reporter group from the resulting hexadecenal, specificity towards sphingolipid labeling can be achieved by blocking sphingosine-1-phosphate lyase activity and thus preventing sphingosine derivatives to be channeled into the sphingolipid-to-glycerolipid metabolic pathway. Here we report an approach using clustered, regularly interspaced, short palindromic repeats (CRISPR-associated nuclease Cas9 to create a sphingosine-1-phosphate lyase (SGPL1 HeLa knockout cell line to disrupt the sphingolipid-to-glycerolipid metabolic pathway. We found that the lipid and protein compositions as well as sphingolipid metabolism of SGPL1 knock-out HeLa cells only show little adaptations, which validates these cells as model systems to study transient protein-sphingolipid interactions.

Impact of different alginate lyases on combined cellulase–lyase saccharification of brown seaweed

DEFF Research Database (Denmark)

Manns, Dirk Martin; Nyffenegger, Christian; Saake, B.

2016-01-01

-guluronic acid. When applied together with a fungal cellulase preparation (Cellic®CTec2) at pH 6 and 40 °C on a glucan rich brown seaweed Laminaria digitata the viscosity decreased in the initial minutes while measurable alginate degradation occurred primarily within the first 1–2 hours of reaction. Whereas FALy......, indicating that the degradation of mannuronic acid blocks inhibited cellulase catalyzed glucose release from L. digitata. Nevertheless, combined alginate lyase and cellulase treatment for 24 hours released all potential glucose regardless of the applied lyase. The enzymatic treatment moreover induced...

Enhancing RGI lyase thermostability by targeted single point mutations

DEFF Research Database (Denmark)

Silva, Inês R.; Larsen, Dorte Møller; Jers, Carsten

2013-01-01

Rhamnogalacturonan I lyase (RGI lyase) (EC 4.2.2.-) catalyzes the cleavage of rhamnogalacturonan I in pectins by β-elimination. In this study the thermal stability of a RGI lyase (PL 11) originating from Bacillus licheniformis DSM 13/ATCC14580 was increased by a targeted protein engineering...

Structural insights into RipC, a putative citrate lyase β subunit from a Yersinia pestis virulence operon

International Nuclear Information System (INIS)

Torres, Rodrigo; Chim, Nicholas; Sankaran, Banumathi; Pujol, Céline; Bliska, James B.; Goulding, Celia W.

2011-01-01

Comparison of the 2.45 Å resolution crystal structure of homotrimeric RipC, a putative citrate lyase β subunit from Y. pestis, with structural homologs reveals conserved RipC residues that are implicated in CoA binding. Yersinia pestis remains a threat, with outbreaks of plague occurring in rural areas and its emergence as a weapon of bioterrorism; thus, an improved understanding of its various pathogenicity pathways is warranted. The rip (required for intracellular proliferation) virulence operon is required for Y. pestis survival in interferon-γ-treated macrophages and has been implicated in lowering macrophage-produced nitric oxide levels. RipC, one of three gene products from the rip operon, is annotated as a citrate lyase β subunit. Furthermore, the Y. pestis genome lacks genes that encode citrate lyase α and γ subunits, suggesting a unique functional role of RipC in the Y. pestisrip-mediated survival pathway. Here, the 2.45 Å resolution crystal structure of RipC revealed a homotrimer in which each monomer consists of a (β/α) 8 TIM-barrel fold. Furthermore, the trimeric state was confirmed in solution by size-exclusion chromatography. Through sequence and structure comparisons with homologous proteins, it is proposed that RipC is a putative CoA- or CoA-derivative binding protein

Thermoluminescence of calcium-based phosphors

International Nuclear Information System (INIS)

Sunta, C.M.

1985-01-01

The paper reviews the thermoluminescence (TL) properties of calcium fluoride, calcium sulphate and calcium carbonate phosphors. In the case of the calcium fluoride mineral phosphor the main emitter of TL is the cerium impurity. Based on the TL emission spectra, two types of Ce 3+ centres can be easily distinguished; those associated with O 2- compensating ion and those which have either no local compensators or are associated with F - interstitial ions at the adjacent vacant body centre position. The spectra undergo remarkable changes at high doses. Such changes are associated with the probabilities of charge trapping at different types of traps and also with the probabilities of recombination at different types of luminescent centres. Some of the traps and recombination centres are spatially associated while others are distributed randomly. In calcium carbonate mineral, Mn 2+ is invariably the emitting impurity. Mn 2+ can be used as an efficient dopant for TL emission in all the three calcium based TL phosphors. A co-dopant like Ce 3+ intensifies the luminescence yield from Mn 2+ . Models of different types of electron and hole trapping centres are given. (author)

Process for winning uranium from wet process phosphoric acid

International Nuclear Information System (INIS)

1980-01-01

A process is described for winning uranium from wet process phosphoric acid by means of liquid-liquid extraction with organic phosphoric acid esters. The process is optimised by keeping the sulphate percentage in the phosphoric acid below 2% by weight, and preferably below 0.6% by weight, as compared to P 2 O 5 in the phosphoric acid. This is achieved by adding an excess of Ba and/or Ca carbonate or sulfide solution and filtering off the formed calcium and/or barium sulphate precipitates. Solid KClO 3 is then added to the filtrate to oxidise U 4+ to U 6+ . The normal extraction procedure using organic phosphoric esters as extraction liquid, can then be applied. (Th.P.)

Catalytic-site mapping of pyruvate formate lyase. Hypophosphite reaction on the acetyl-enzyme intermediate affords carbon-phosphorus bond synthesis (1-hydroxyethylphosphonate).

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Plaga, W; Frank, R; Knappe, J

1988-12-15

Pyruvate formate-lyase of Escherichia coli cells, a homodimeric protein of 2 x 85 kDa, is distinguished by the property of containing a stable organic free radical (g = 2.0037) in its resting state. The enzyme (E-SH) achieves pyruvate conversion to acetyl-CoA via two distinct half-reactions (E-SH + pyruvate in equilibrium E-S-acetyl + formate; E-S-acetyl + CoA in equilibrium E-SH + acetyl-CoA), the first of which has been proposed to involve reversible homolytic carbon-carbon bond cleavage [J. Knappe et al. (1984) Proc. Natl Acad. Sci. USA 81, 1332-1335]. Present studies identified Cys-419 as the covalent-catalytic cysteinyl residue via CNBr fragmentation of E-S-[14C]acetyl and radio-sequencing of the isolated peptide CB-Ac (amino acid residues 406-423). Reaction of the formate analogue hypophosphite with E-S-acetyl was investigated and found to produce 1-hydroxyethylphosphonate with a thioester linkage to the adjacent Cys-418. The structure was determined from the chymotryptic peptide CH-P (amino acid residues 415-425), using 31P-NMR spectroscopy (delta = 44 ppm) and by chemical characterisation through degradation into 1-hydroxyethylphosphonate with phosphodiesterase or bromine. This novel P-C-bond synthesis involves the enzyme-based free radical and is proposed to resemble the physiological C-C-bond synthesis (pyruvate production) from formate and E-S-acetyl. These findings are interpreted as proof of a radical mechanism for the action of pyruvate formate-lyase. The central Cys-418/Cys-419 pair of the active site shows a distinctive thiolate property even in the inactive (nonradical) form of the enzyme, as determined using an iodoacetate probe.

Enzymatic description of the anhydrofructose pathway of glycogen degradation. I

DEFF Research Database (Denmark)

Yu, Shukun; Refdahl, Charlotte; Lundt, Inge

2004-01-01

The anhydrofructose pathway describes the degradation of glycogen and starch to metabolites via 1,5-anhydro-D-fructose (1,5AnFru). The enzyme catalyzing the first reaction step of this pathway, i.e., a-1,4-glucan lyase (EC 4.2.1.13), has been purified, cloned and characterized from fungi and red...... possessed all enzymes needed for conversion of glycogen to APP, an a-1,4-glucan lyase from this fungus was isolated and partially sequenced. Based on this work, a scheme of the enzymatic description of the anhydrofructose pathway in A. melaloma was proposed. Keywords: Anhydrofructose pathway; Anthracobia...

Molecular characterization of a Penicillium chrysogenum exo-rhamnogalacturonan lyase that is structurally distinct from other polysaccharide lyase family proteins.

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Iwai, Marin; Kawakami, Takuya; Ikemoto, Takeshi; Fujiwara, Daisuke; Takenaka, Shigeo; Nakazawa, Masami; Ueda, Mitsuhiro; Sakamoto, Tatsuji

2015-10-01

We previously described an endo-acting rhamnogalacturonan (RG) lyase, termed PcRGL4A, of Penicillium chrysogenum 31B. Here, we describe a second RG lyase, called PcRGLX. We determined the cDNA sequence of the Pcrglx gene, which encodes PcRGLX. Based on analyses using a BLAST search and a conserved domain search, PcRGLX was found to be structurally distinct from known RG lyases and might belong to a new polysaccharide lyase family together with uncharacterized fungal proteins of Nectria haematococca, Aspergillus oryzae, and Fusarium oxysporum. The Pcrglx cDNA gene product (rPcRGLX) expressed in Escherichia coli demonstrated specific activity against RG but not against homogalacturonan. Divalent cations were not essential for the enzymatic activity of rPcRGLX. rPcRGLX mainly released unsaturated galacturonosyl rhamnose (ΔGR) from RG backbones used as the substrate from the initial stage of the reaction, indicating that the enzyme can be classified as an exo-acting RG lyase (EC 4.2.2.24). This is the first report of an RG lyase with this mode of action in Eukaryota. rPcRGLX acted synergistically with PcRGL4A to degrade soybean RG and released ΔGR. This ΔGR was partially decorated with galactose (Gal) residues, indicating that rPcRGLX preferred oligomeric RGs to polymeric RGs, that the enzyme did not require Gal decoration of RG backbones for degradation, and that the enzyme bypassed the Gal side chains of RG backbones. These characteristics of rPcRGLX might be useful in the determination of complex structures of pectins.

Pathway confirmation and flux analysis of central metabolicpathways in Desulfovibrio vulgaris Hildenborough using gaschromatography-mass spectrometry and fourier transform-ion cyclotronresonance mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Tang, Yinjie; Pingitore, Francesco; Mukhopadhyay, Aindrila; Phan,Richard; Hazen, Terry C.; Keasling, Jay D.

2006-07-11

It has been proposed that during growth under anaerobic oroxygen-limited conditions Shewanella oneidensis MR-1 uses theserine-isocitrate lyase pathway common to many methylotrophic anaerobes,in which formaldehyde produced from pyruvate is condensed with glycine toform serine. The serine is then transformed through hydroxypyruvate andglycerate to enter central metabolism at phosphoglycerate. To examine itsuse of the serine-isocitrate lyase pathway under anaerobic conditions, wegrew S. oneidensis MR-1 on [1-13C]lactate as the sole carbon source witheither trimethylamine N-oxide (TMAO) or fumarate as an electron acceptor.Analysis of cellular metabolites indicates that a large percentage(>75 percent) of lactate was partially oxidized to either acetate orpyruvate. The 13C isotope distributions in amino acids and other keymetabolites indicate that, under anaerobic conditions, a complete serinepathway is not present, and lactate is oxidized via a highly reversibleserine degradation pathway. The labeling data also suggest significantactivity in the anaplerotic (malic enzyme and phosphoenolpyruvatecarboxylase) and glyoxylate shunt (isocitrate lyase and malate synthase)reactions. Although the tricarboxylic acid (TCA) cycle is often observedto be incomplete in many other anaerobes (absence of 2-oxoglutaratedehydrogenase activity), isotopic labeling supports the existence of acomplete TCA cycle in S. oneidensis MR-1 under TMAO reductioncondition.

Hydrogen Oxidation on Gas Diffusion Electrodes for Phosphoric Acid Fuel Cells in the Presence of Carbon Monoxide and Oxygen

DEFF Research Database (Denmark)

Gang, Xiao; Li, Qingfeng; Hjuler, Hans Aage

1995-01-01

Hydrogen oxidation has been studied on a carbon-supported platinum gas diffusion electrode in a phosphoric acidelectrolyte in the presence of carbon monoxide and oxygen in the feed gas. The poisoning effect of carbon monoxide presentin the feed gas was measured in the temperature range from 80...... to 150°C. It was found that throughout the temperaturerange, the potential loss due to the CO poisoning can be reduced to a great extent by the injection of small amounts ofgaseous oxygen into the hydrogen gas containing carbon monoxide. By adding 5 volume percent (v/o) oxygen, an almost...

Generation of 2-Furfurylthiol by Carbon-Sulfur Lyase from the Baijiu Yeast Saccharomyces cerevisiae G20.

Science.gov (United States)

Zha, Musu; Sun, Baoguo; Yin, Sheng; Mehmood, Arshad; Cheng, Lei; Wang, Chengtao

2018-03-07

2-Furfurylthiol is the representative aroma compound of Chinese sesame-flavored baijiu. Previous studies demonstrated that baijiu yeasts could generate 2-furfurylthiol using furfural and l-cysteine as precursors and that the Saccharomyces cerevisiae genes STR3 and CYS3 are closely related to 2-furfurylthiol biosynthesis. To confirm the mechanism of the STR3- and CYS3-gene products on 2-furfurylthiol biosynthesis, their encoded proteins were purified, and we confirmed their activities as carbon-sulfur lyases. Str3p and Cys3p were able to cleave the cysteine-furfural conjugate to release 2-furfurylthiol. Moreover, the characterization of the enzymatic properties of the purified proteins shows good thermal stabilities and wide pH tolerances, which enable their strong potential for various applications. These data provide direct evidence that yeast Str3p and Cys3p release 2-furfurylthiol in vitro, which can be applied to improve baijiu flavor.

Cooperative functioning between phenylalanine ammonia lyase and isochorishmate synthase activities contributes to salicylic acid biosynthesis in soybean

Science.gov (United States)

Salicylic acid (SA), an essential regulator of plant defense, is derived from chorismate via either the phenylalanine ammonia lyase (PAL), or the isochorishmate synthase (ICS) catalyzed steps. The ICS pathway is thought to be the primary contributor of defense-related SA, at least in Arabidopsis. We...

Transition of Emission Colours as a Consequence of Heat-Treatment of Carbon Coated Ce3+-Doped YAG Phosphors

NARCIS (Netherlands)

Yin, L.J.; Dierre, B.F.P.R.; Sekiguchi, Takashi; van Ommen, J.R.; Hintzen, H.T.J.M.; Cho, Yujin

2017-01-01

To modify the luminescence properties of Ce³⁺-doped Y₃Al₅O₁₂ (YAG) phosphors, they have been coated with a carbon layer by chemical vapor deposition and subsequently heat-treated at high temperature under N₂ atmosphere. Luminescence of the

One-step purification and characterization of alginate lyase from a clinical Pseudomonas aeruginosa with destructive activity on bacterial biofilm

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Parinaz Ghadam

2017-05-01

Full Text Available Objective(s: Pseudomonas aeruginosais a Gram-negative and aerobic rod bacterium that displays mucoid and non-mucoid phenotype. Mucoid strains secrete alginate, which is the main agent of biofilms in chronic P. aeruginosa infections, show high resistance to antibiotics; consequently, the biological disruption of mucoid P. aeruginosa biofilms is an attractive area of study for researchers. Alginate lyase gene (algl is a member of alginate producing operon which by glycosidase activity produces primer for other enzymes in this cluster. Also this activity can destroy the extracellular alginate; therefore this enzyme participates in alginate production and destruction pathway. Alginate lyase causes detachment of a biofilm by reducing its adhesion to the surfaces, and increases phagocytosis and antibiotic susceptibility. In this study, alginate lyase was purified in just one step and its properties were investigated. Materials and Methods: The purification was done by affinity chromatography, analysed by SDS-PAGE, and its effect on P. aeruginosa biofilms was surveyed by micro titer plate assay and SEM. The substrate specificity of the enzyme was determined by PCR. Results: Alginate lyase from isolate 48 was purified in one step. It is more thermally resistant than alginate lyase from Pseudomonas aeruginosa PAO1 and poly M, poly G and poly MG alginate were the substrate of this enzyme. Moreover, it has an eradication effect on biofilms from P. aeruginosa 48 and PAO1. Conclusion: In this study an alginate lyase with many characteristics suitable in medicine such as thermal stability, effective on poly M alginate, and bacterial biofilm destructive was introduced and purified.

Increased protein expression of LHCG receptor and 17a-hydroxylase/17,20-lyase in human polycystic ovaries

NARCIS (Netherlands)

Comim, F.V.; Teerds, K.J.; Hardy, K.; Franks, S.

2013-01-01

STUDY QUESTION Does the expression of LHCG receptor (LHCGR) protein and key enzymes in the androgen biosynthetic pathway differ in normal human versus polycystic ovarian tissue? SUMMARY ANSWER LHCGR and 17a-hydroxylase/17-20-lyase (CYP17A1) protein levels are increased in polycystic ovaries (PCOs).

Preparation of high purification and food grade phosphoric acid from technical grade phosphoric acid by liquid-liquid detraction method

International Nuclear Information System (INIS)

Alimoradi, M.; Borji, F.; Kishani, A.

2002-01-01

Pay attention to increasing consumption of high purification and food grade phosphoric acid in various industries and food industries and on in on hand and lack of preparation between production and distribution of this products its purification is so vital. In this article of liquid-liquid extraction method with normal hexane-mixture of ammonia and acetone-diisopropyl alcohol and normal butanol solvents and these determination of distribution coefficient each one with ph-me try titration we can evaluate effectiveness and sufficiency each one. Because of proper coefficient distribution and its local production of normal butanol solvent and low price is the best solvent. To phosphoric acid modifying coefficient distribution for extraction of phosphoric acid we can add a little value sulfuric acid to the mixture and to remove flouride impurity we add a little Na 2 O. After extraction stage extracted phosphoric acid in the normal strips by evaluating with distilled water and then by passing the carbon active bed and following passes of cationic resine column and concentrated with vacuum distillation. Conclusion of this article is produce of phosphoric acid 85% w/w and food grade from impure phosphoric acid 52% w/w with technical grade

In Silico Characterization of Pectate Lyase Protein Sequences from Different Source Organisms

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Amit Kumar Dubey

2010-01-01

Full Text Available A total of 121 protein sequences of pectate lyases were subjected to homology search, multiple sequence alignment, phylogenetic tree construction, and motif analysis. The phylogenetic tree constructed revealed different clusters based on different source organisms representing bacterial, fungal, plant, and nematode pectate lyases. The multiple accessions of bacterial, fungal, nematode, and plant pectate lyase protein sequences were placed closely revealing a sequence level similarity. The multiple sequence alignment of these pectate lyase protein sequences from different source organisms showed conserved regions at different stretches with maximum homology from amino acid residues 439–467, 715–816, and 829–910 which could be used for designing degenerate primers or probes specific for pectate lyases. The motif analysis revealed a conserved Pec_Lyase_C domain uniformly observed in all pectate lyases irrespective of variable sources suggesting its possible role in structural and enzymatic functions.

Crystallization and preliminary X-ray analysis of an exotype alginate lyase Atu3025 from Agrobacterium tumefaciens strain C58, a member of polysaccharide lyase family 15

International Nuclear Information System (INIS)

Ochiai, Akihito; Yamasaki, Masayuki; Mikami, Bunzo; Hashimoto, Wataru; Murata, Kousaku

2006-01-01

The crystallization and preliminary X-ray characterization of a family PL-15 exotype alginate lyase are presented. Almost all alginate lyases depolymerize alginate in an endolytical fashion via a β-elimination reaction. The alginate lyase Atu3025 from Agrobacterium tumefaciens strain C58, consisting of 776 amino-acid residues, is a novel exotype alginate lyase classified into polysaccharide lyase family 15. The enzyme was crystallized at 293 K by sitting-drop vapour diffusion with polyethylene glycol 4000 as a precipitant. Preliminary X-ray analysis showed that the Atu3025 crystal belonged to space group P2 1 and diffracted to 2.8 Å resolution, with unit-cell parameters a = 107.7, b = 108.3, c = 149.5 Å, β = 91.5°

Enantioselective Synthesis of Various Cyanohydrins Using Covalently Immobilized Preparations of Hydroxynitrile Lyase from Prunus dulcis.

Science.gov (United States)

Alagöz, Dilek; Tükel, S Seyhan; Yildirim, Deniz

2015-11-01

The carrier-based and carrier-free (cross-linked enzyme aggregate) covalent immobilizations of Prunus dulcis hydroxynitrile lyase were investigated. The immobilized preparations were tested for enantioselective carbon-carbon bond formation activity in the biphasic medium. Of the tested preparations, only cross-linked enzyme aggregate of P. dulcis hydroxynitrile lyase (PdHNL-CLEA) achieved the synthesis of (R)-mandelonitrile with 93% yield and 99% enantiopurity. PdHNL-CLEA was also used in the synthesis of various (R)-cyanohydrins from corresponding aldehydes/ketones and hydrocyanic acid. When 4-methoxybenzaldehyde, 4-methyl benzaldehyde, and 4-hydroxybenzaldehyde were used as substrates, the yield-enantiomeric excess of corresponding (R)-cyanohydrins were obtained as 95-95, 85-79, and 2-25%, respectively, after 96 h at pH 4.0 and 5 °C. For acetophenone, 4-fluoroacetophenone, 4-chloroacetophenone, 4-bromoacetophenone, and 4-iodoacetophenone, the yield-enantiomeric excess of corresponding (R)-cyanohydrins were 1-99, 20-84, 11-95, 5-99, and 3-24%, respectively at the same conditions. The results demonstrate PdHNL-CLEA can be effectively used in the synthesis of (R)-mandelonitrile.

Physicochemical properties of carbons prepared from pecan shell by phosphoric acid activation.

Science.gov (United States)

Guo, Yanping; Rockstraw, David A

2007-05-01

Activated carbons were prepared from pecan shell by phosphoric acid activation. The pore structure and acidic surface groups of these carbons were characterized by nitrogen adsorption, Boehm titration and transmittance Fourier infrared spectroscopy (FTIR) techniques. The characterization results demonstrated that the development of pore structure was apparent at temperatures 250 degrees C, and reached 1130m(2)/g and 0.34cm(3)/g, respectively, at 500 degrees C. Impregnation ratio and soaking time at activation temperature also affected the pore development and pore size distribution of final carbon products. At an impregnation ratio of 1.5, activated carbon with BET surface area and micropore volume as high as 861m(2)/g and 0.289cm(3)/g was obtained at 400 degrees C. Microporous activated carbons were obtained in this study. Low impregnation ratio (less than 1.5) and activation temperature (less than 300 degrees C) are favorable to the formation of acidic surface functional groups, which consist of temperature-sensitive (unstable at high temperature) and temperature-insensitive (stable at high temperature) two parts. The disappearance of temperature-sensitive groups was significant at temperature 300 degrees C; while the temperature-insensitive groups are stable even at 500 degrees C. FTIR results showed that the temperature-insensitive part was mostly phosphorus-containing groups as well as some carbonyl-containing groups, while carbonyl-containing groups were the main contributor of temperature-sensitive part.

Purification and Characterization of a Unique Pectin Lyase from Aspergillus giganteus Able to Release Unsaturated Monogalacturonate during Pectin Degradation

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Danielle Biscaro Pedrolli

2014-01-01

Full Text Available A pectin lyase, named PLIII, was purified to homogeneity from the culture filtrate of Aspergillus giganteus grown in submerged culture containing orange peel waste as carbon source. PLIII was able to digest apple pectin and citrus pectins with different degrees of methyl esterification. Interestingly, the PLIII activity was stimulated in the presence of some divalent cations including Pb2+ and was not significantly affected by Hg2+. Like other pectin lyases, PLIII is stimulated by but is not dependent on Ca2+. The main soluble product released during the degradation of pectic substances promoted by the PLIII is compatible with an unsaturated monogalacturonate. PLIII is a unique enzyme able to release unsaturated monogalacturonate as the only soluble product during the degradation of pectic substances; therefore, PLIII was classified as an exo-pectin lyase. To our knowledge, this is the first characterization of an exo-pectin lyase. The PLIII described in this work is potentially useful for ethanol production from pectin-rich biomass, besides other common applications for alkaline pectinases like preparation of textile fibers, coffee and tea fermentation, vegetable oil extraction, and the treatment of pulp in papermaking.

Pathways to Carbon-Negative Liquid Biofuels

Science.gov (United States)

Woolf, D.; Lehmann, J.

2017-12-01

Many climate change mitigation scenarios assume that atmospheric carbon dioxide removal will be delivered at scale using bioenergy power generation with carbon capture and storage (BECCS). However, other pathways to negative emission technologies (NETs) in the energy sector are possible, but have received relatively little attention. Given that the costs, benefits and life-cycle emissions of technologies vary widely, more comprehensive analyses of the policy options for NETs are critical. This study provides a comparative assessment of the potential pathways to carbon-negative liquid biofuels. It is often assumed that that decarbonisation of the transport sector will include use of liquid biofuels, particularly for applications that are difficult to electrify such as aviation and maritime transport. However, given that biomass and land on which to grow it sustainably are limiting factors in the scaling up of both biofuels and NETs, these two strategies compete for shared factors of production. One way to circumvent this competition is carbon-negative biofuels. Because capture of exhaust CO2 in the transport sector is impractical, this will likely require carbon capture during biofuel production. Potential pathways include, for example, capture of CO2 from fermentation, or sequestration of biochar from biomass pyrolysis in soils, in combination with thermochemical or bio-catalytic conversion of syngas to alcohols or alkanes. Here we show that optimal pathway selection depends on specific resource constraints. As land availability becomes increasingly limiting if bioenergy is scaled up—particularly in consideration that abandoned degraded land is widely considered to be an important resource that does not compete with food fiber or habitat—then systems which enhance land productivity by increasing soil fertility using soil carbon sequestration become increasingly preferable compared to bioenergy systems that deplete or degrade the land resource on which they

Cloning and expression of isocitrate lyase from human round worm Strongyloides stercoralis

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Siddiqui A.A.

2000-09-01

Full Text Available A full length cDNA (1463 bp encoding isocitrate lyase (EC 4.1.3.1 of Strongyloides stercoralis is described. The nucleotide sequence of this insert identified a cDNA coding for the isocitrate lyase. The conceptually translated amino acid sequence of the open reading frame for S. stercoralis isocitrate lyase encodes a 450 amino acid residue protein with an apparent molecular weight of 50 kDa and a predicted pl of 6.39. The sequence is 69 % A/T, reflecting a characteristic A/T codon bias of S. stercoralis. The amino acid sequence of S. stercoralis isocitrate lyase is compared with bifunctional glyoxylate cycle protein of Caenorhabditis elegans and isocitrate lyases from Chlamydomonas reinhardtii and Myxococcus xanthus. The full length cDNA of S. stercoralis was expressed in pRSET vector and bacteriophage T7 promoter based expression system. S. stercoralis lyase recombinant protein, purified via immobilized metal affinity chromatography, showed a molecular mass of 50 kDa on polyacrylamide gels. The role of isocitrate lyase in the glyoxylate cycle and energy metabolism of S. stercoralis is also discussed.

Preparation and Characterization of Various Activated Carbons Derived From Mixed Precursors Using Phosphoric Acid

International Nuclear Information System (INIS)

Daifullah, A.A.M.; Sharaf El-Deen, S.E.A.; Elkhalafawy, A.; Shehata, F.A.; Mahmoud, W.H.

2008-01-01

Rice straw (RS) and rice husk (RH), a low-cost agricultural by-products, have been used as a mixed precursor (i.e., RS mixed with RH in 1:1; 1:3 and 3:1 ratios) for the production of novel carbons using phosphoric acid as chemical activation. The raw materials were impregnated with 50% and 70% H 3 PO 4 followed by activation at 500 degree C. The latter proved to be the most effective in producing active carbon with good adsorptive capacity. The resulting carbons were characterized by elemental analysis, infrared spectroscopy, density, SEM and S BET . In general, the resulting carbons showed reasonable surface areas with mainly micropore structure. The adsorption capacity was demonstrated by the isotherms of methylene blue (MB), phenol and iodine from aqueous solution. The adsorption data was found to conform with the Langmuir equation with the concentration range studied, and the monolayer coverage was determined for each of the samples. It was found that surface area is mainly attributed to micropore volume so that phenol adsorption and iodine number correspond well with surface area determined by nitrogen adsorption

Carbon-13 kinetic isotope effects in the decarbonylation of lactic acid of natural isotopic composition in phosphoric acid medium

International Nuclear Information System (INIS)

Zielinski, M.; Czarnota, G.; Papiernik-Zielinska, H.; Kasprzyk, G.; Gumolka, L.; Staedter, W.

1993-01-01

The 13 C kinetic isotope effect fractionation in the decarbonylation of lactic acid (LA) of natural isotopic composition by concentrated phosphoric acids (PA) and by 85% H 3 PO 4 has been studied in the temperature interval of 60-150 deg C. The values of the 13 C (1) isotope effects in the decarbonylation of lactic acid in 100% H 3 PO 4 , in pyrophosphoric acid and in more concentrated phosphoric acids are intermediate between the values calculated assuming that the C (1)- OH bond is broken in the rate-controlling step of dehydration and those calculated for rupture of the carbon-carbon bond in the transition state. In the temperature interval of 90-130 deg C the experimental 13 C fractionation factors determined in concentrated PA approach quite closely the 13 C fractionation corresponding to C (2)- C (1) bond scission. The 13 C (1) kinetic isotope effects in the decarbonylation of LA in 85% orthophosphoric acid in the temperature range of 110-150 deg C coincide with the 13 C isotope effects calculated assuming that the frequency corresponding to the C (1) -OH vibration is lost in the transition state of decarbonylation. A change of the mechanism of decarbonylation of LA in going from concentrated PA medium to 85% H 3 PO 4 has been suggested. A possible secondary 18 O and a primary 18 O kinetic isotope effect in decarbonylation of lactic acid in phosphoric acids media have been discussed, too. (author) 21 refs.; 3 tabs

The hydroxynitrile lyase from almond: crystal structure and mechanistical studies

International Nuclear Information System (INIS)

Dreveny, Ingrid

2001-09-01

Cyanogenesis is a defense process of several thousand plant species. Hydroxynitrile lyase (HNL), a key enzyme of this process, cleaves a cyanohydrin precursor into hydrocyanic acid and the corresponding aldehyde or ketone. The reverse reaction constitutes an important tool in industrial biocatalysis. Different classes of hydroxynitrile lyases have convergently evolved from FAD-dependent oxidoreductases, α/β hydrolases and alcohol dehydrogenases. The FAD-dependent hydroxynitrile lyases (FAD-HNLs) carry a flavin cofactor whose redox properties appear to be unimportant for catalysis. The high resolution crystal structure of the hydroxynitrile lyase from almond (Prunus amygdalus), PaHNL1, has been determined and constitutes the first 3D structure of an FAD-HNL. The overall fold and the architecture of the active site region showed that PaHNL1 belongs to the glucose-methanol-choline-oxidoreductase family, with closest structural similarity to glucose oxidase. There is strong evidence from the sequence and the reaction product that FAD-dependent hydroxynitrile lyases have evolved from an aryl alcohol oxidizing precursor. Structures of PaHNL1 in complex with its natural substrate mandelonitrile and the competitive inhibitor benzyl alcohol provided insight into the residues involved in catalysis and a mechanism without participation of the cofactor could be suggested. Although the catalytic residues differ between the α/β-hydrolase-type HNLs and PaHNL1, common general features relevant for hydroxynitrile lyase activity could be proposed. (author)

Studies on pectin lyase

NARCIS (Netherlands)

Houdenhoven, van F.E.A.

1975-01-01

The pectin lyase activity in the commercial enzyme preparation Ultrazym originates from more then one type of enzyme; two of them, accounting for 95 % of the total activity, have been completely purified. As purity criteria specific activity, polyacrylamide disc gel electrophoresis and SDS

Design and development of low-power driven hybrid electroluminescent lamp from carbon nanotube embedded phosphor material

International Nuclear Information System (INIS)

Yadav, Deepika; Mishra, Savvi; Shanker, Virendra; Haranath, D.

2013-01-01

Highlights: •We are first to report CNT embedded ZnS:Mn hybrid EL system. •Achieved efficient orange-red EL emission at low operating voltages ( AC ). •Facile technique to induce conductive paths inside the ZnS particle to trigger EL. •Detailed electrical characterization of EL lamp is presented. -- Abstract: We present a novel methodology to design a hybrid electroluminescent (EL) lamp by embedding carbon nanotubes (CNTs) inside the ZnS:Mn phosphor particles by conventional solid state diffusion technique. By doing so, the phosphor particles exhibited increase in EL brightness and efficiency at low operating voltages ( AC ). Interestingly, shorter the length of CNTs used, greater was the field enhancement effect and lower was the operating voltages to glow the EL lamps. The role of CNTs have been identified to form conductive paths inside the ZnS particle thereby triggering EL due to electron injection to luminescent centers (Mn 2+ ) at nominal voltages. In addition, a detailed electrical characterization of the novel EL lamp along with its spectral energy distribution studies are presented

Thermal Effect on the phosphoric Acid Impregnated Activated Carbon Fiber and Adsorption Properties Toward Isoprene

Energy Technology Data Exchange (ETDEWEB)

Hwang, Taek Sung; Lee, Jin Hyok; Kang, Kyung suk [Department of Chemical Engineering, College of Engineering, Chungnam National University, Taejon (Korea); Kim, Kwang Young [Ace Lab. Co. Ltd. Taejon (Korea); Rhee, Moon Soo [Korea Ginseng and Tobacoo Research Institute, Taejon (Korea)

2001-05-01

To introduce chemisorption property and improve adsorption capacities for isoprene, ACF (Activated Carbon Fiber) was impregnated by phosphoric acid. As the impregnated ACF was dried by programmed temperature from 300 degree C to 500 degree C, degree of impregnation, surface area, thermal stability and adsorption properties for isoprene were observed. The degree of impregnation of the ACF, dried at the 400 degree C, was 12.7 w/w% and surface area was 1148 m{sup 2}/g. Over the temperature range of 450 degree C to 700 degree C, there was one-step thermal degradation by the thermal decomposition of phosphonyl group. The adsorption rate of phosphoric acid on the impregnated ACF, which was dried at 400 degree C, was the fastest. The breakthrough time of ACF that was dried at 400 degree C was 18 min., and its adsorption capacity improved roughly 7.2 times in comparison to the pure ACF. In addition, it was observed the adsorption properties persisted even after the regeneration. The adsorption efficiency of regenerated ACF was 66 percent compared to the unused impregnated ACF. 21 refs., 7 figs., 3 tabs.

Raman Spectra of Luminescent Graphene Oxide (GO-Phosphor Hybrid Nanoscrolls

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Janardhanan. R. Rani

2015-12-01

Full Text Available Graphene oxide (GO-phosphor hybrid nanoscrolls were synthesized using a simple chemical method. The GO-phosphor ratio was varied to find the optimum ratio for enhanced optical characteristics of the hybrid. A scanning electron microscope analysis revealed that synthesized GO scrolls achieved a length of over 20 μm with interior cavities. The GO-phosphor hybrid is extensively analyzed using Raman spectroscopy, suggesting that various Raman combination modes are activated with the appearance of a low-frequency radial breathing-like mode (RBLM of the type observed in carbon nanotubes. All of the synthesized GO-phosphor hybrids exhibit an intense luminescent emission around 540 nm along with a broad emission at approximately 400 nm, with the intensity ratio varying with the GO-phosphor ratio. The photoluminescence emissions were gauged using Commission Internationale d'Eclairage (CIE coordinates and at an optimum ratio. The coordinates shift to the white region of the color spectra. Our study suggests that the GO-phosphor hybrid nanoscrolls are suitable candidates for light-emitting applications.

Co-precipitation synthesis and luminescence behavior of Ce-doped yttrium aluminum garnet (YAG:Ce) phosphor: The effect of precipitant

International Nuclear Information System (INIS)

Zhang Kai; Liu Hezhou; Wu Yating; Hu Wenbin

2008-01-01

YAG:Ce precursors were co-precipitated using ammonia water and ammonium hydrogen carbonate as precipitants, respectively. Phase transition of the precursors during sintering was compared between the two precipitants. The precursors synthesized with ammonia water transformed to YAG at about 1000 deg. C via YAlO 3 phase. The precursors synthesized with ammonium hydrogen carbonate directly converted to pure YAG at about 900 deg. C. Comparing the powders produced with the two precipitants, the powders produced with ammonia hydrogen carbonate showed good dispersity. When sintered at 1600 deg. C, aggregation of the powders synthesized with the two precipitants both became severe. With increase the sintering temperature, the maximum wavelength of excitation and emission spectra of the phosphors synthesized with ammonium water hardly varied. While the maximum wavelength of excitation spectra of the phosphors synthesized with ammonium hydrogen carbonate unchanged, and the emission spectra showed red shift. Because of size effect and higher loss of cerium content, the emission intensity of phosphors prepared with ammonium hydrogen carbonate was lower than the phosphors prepared with ammonium water, when sintered at the same temperature

Pretreatment of phosphoric acid of Annaba

International Nuclear Information System (INIS)

Kada, R.

1990-03-01

The most important step in the process of uranium recovery from phosphoric acid is the pretreatment operation. In this study, the adsorption of organic matters on activated carbon was carried out in a batch process and in a fixed bed column. First, the chemical and physical characterization of phosphoric acid, activated carbon and gypsum were performed. In addition, the organic matters were qualitatively analysed and a new and original quantitative method was experimented. Next, the various operating parameters such as agitation speed, granulometry, temperature, solid/liquid ratio, initial concentration, acid flowrate, and bed height were optimized. The experimental equilibrium isotherm was compared to the Langmuir, Freundlich, and Redlich-Peterson theoretical isotherms. It was noticed that the three models did not fit the experimental isotherm in the total concentration range. Thus, an original bilinear model was proposed. The influence of the operating conditions on the adsorption kinetics was also investigated. As a result of that, a new mathematical model was proposed to determine both the liquid and solid phases mass transfer and the solid phase diffusion coefficient. Finally, adsorption of organic matters on a fixed bed process allowed computation of the number of transfer units (NTU), the height of adsorption zone and the degree of saturation of activated carbon

Phosphors

International Nuclear Information System (INIS)

1975-01-01

This invention relates to phosphors that can be used in fluorescent lamps and display devices. The phosphor is comprised of a halophosphate of calcium and/or strontium of apatite crystal structure activated with trivalent cerium and trivalent terbium. The phosphor can further include manganese. Preferably, the phosphor includes up to 10% by weight of one or more of the alkali metals lithium, sodium and potassium in the form of a compound or compounds thereof. The emissions appear as a number of fairly narrow discrete bands. The temperature of preparation is 1000degC (as opposed to the usual 1450degC), therefore reducing costs (less energy is needed, more crucibles are readily obtainable and there is no need for special conditions to enable crucibles to overcome thermal shock)

Uranium recovery from wet process phosphoric acid

International Nuclear Information System (INIS)

Carrington, O.F.; Pyrih, R.Z.; Rickard, R.S.

1981-01-01

Improvement in the process for recovering uranium from wetprocess phosphoric acid solution derived from the acidulation of uraniferous phosphate ores by the use of two ion exchange liquidliquid solvent extraction circuits in which in the first circuit (A) the uranium is reduced to the uranous form; (B) the uranous uranium is recovered by liquid-liquid solvent extraction using a mixture of mono- and di-(Alkyl-phenyl) esters of orthophosphoric acid as the ion exchange agent; and (C) the uranium oxidatively stripped from the agent with phosphoric acid containing an oxidizing agent to convert uranous to uranyl ions, and in the second circuit (D) recovering the uranyl uranium from the strip solution by liquid-liquid solvent extraction using di(2ethylhexyl)phosphoric acid in the presence of trioctylphosphine oxide as a synergist; (E) scrubbing the uranium loaded agent with water; (F) stripping the loaded agent with ammonium carbonate, and (G) calcining the formed ammonium uranyl carbonate to uranium oxide, the improvement comprising: (1) removing the organics from the raffinate of step (B) before recycling the raffinate to the wet-process plant, and returning the recovered organics to the circuit to substantially maintain the required balance between the mono and disubstituted esters; (2) using hydogren peroxide as the oxidizing agent in step (C); (3) using an alkali metal carbonate as the stripping agent in step (F) following by acidification of the strip solution with sulfuric acid; (4) using some of the acidified strip solution as the scrubbing agent in step (E) to remove phosphorus and other impurities; and (5) regenerating the alkali metal loaded agent from step (F) before recycling it to the second circuit

Circadian Rhythmicity in the Activities of Phenylalanine Ammonia-Lyase from Lemna perpusilla and Spirodela polyrhiza 1

Science.gov (United States)

Gordon, William R.; Koukkari, Willard L.

1978-01-01

The oscillations in phenylalanine ammonia-lyase activity from Spirodela polyrhiza and phenylalanine ammonia-lyase and tyrosine ammonia-lyase activities from Lemna perpusilla displayed a circadian rhythm under continuous light. Rhythmicity in enzymic activity could not be detected in continuous darkness since under this condition phenylalanine ammonia-lyase activity remains at a fairly constantly low level. Results from our studies of the oscillatory pattern of the respective activities of phenylalanine and tyrosine ammonia-lyase support their “inseparability.” PMID:16660569

Possible Roles of Fluoride and Carbonate in Biochemical Carbonated Apatite Formation

Science.gov (United States)

Meouch, Orysia; Omelon, Sidney

2016-04-01

Marine phosphorites are predominantly composed of carbonated fluorapatite (CFA = Ca10-a-b-cNaaMgb(PO4)6-x(CO3)x-y-z(CO3.F)y(SO4)zF2, where x=y+a+2c, and c represents the number of Ca vacancies, with a P2O5 content that ranges from 18-40 %. Sulphur-oxidizing bacteria of the Beggiatoa genus concentration phosphorous as intracellular polyphosphate ((PO3-)n) which is depolymerized into inorganic orthophosphate (Pi). Consequently, an increase in pore water Pi concentration favours carbonated apatite precipitation. The carbonate and fluoride that is characteristic of phosphorite CFA is also located in the vertebrate skeleton. This similarity suggests a biochemical pathway for CFA precipitation. Preliminary Raman spectroscopy and powder x-ray diffraction results that suggest a role for fluoride, and possibly carbonate, in the biochemical depolymerisation of polyphosphates with alkaline phosphatase will be presented.

Characterization of AlgMsp, an alginate lyase from Microbulbifer sp. 6532A.

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Steven M Swift

Full Text Available Alginate is a polysaccharide produced by certain seaweeds and bacteria that consists of mannuronic acid and guluronic acid residues. Seaweed alginate is used in food and industrial chemical processes, while the biosynthesis of bacterial alginate is associated with pathogenic Pseudomonas aeruginosa. Alginate lyases cleave this polysaccharide into short oligo-uronates and thus have the potential to be utilized for both industrial and medicinal applications. An alginate lyase gene, algMsp, from Microbulbifer sp. 6532A, was synthesized as an E.coli codon-optimized clone. The resulting 37 kDa recombinant protein, AlgMsp, was expressed, purified and characterized. The alginate lyase displayed highest activity at pH 8 and 0.2 M NaCl. Activity of the alginate lyase was greatest at 50°C; however the enzyme was not stable over time when incubated at 50°C. The alginate lyase was still highly active at 25°C and displayed little or no loss of activity after 24 hours at 25°C. The activity of AlgMsp was not dependent on the presence of divalent cations. Comparing activity of the lyase against polymannuronic acid and polyguluronic acid substrates showed a higher turnover rate for polymannuronic acid. However, AlgMSP exhibited greater catalytic efficiency with the polyguluronic acid substrate. Prolonged AlgMsp-mediated degradation of alginate produced dimer, trimer, tetramer, and pentamer oligo-uronates.

Isolation and characterization of an Antarctic Flavobacterium strain with agarase and alginate lyase activities

Directory of Open Access Journals (Sweden)

Lavín Paris

2016-09-01

Full Text Available Several bacteria that are associated with macroalgae can use phycocolloids as a carbon source. Strain INACH002, isolated from decomposing Porphyra (Rhodophyta, in King George Island, Antarctica, was screened and characterized for the ability to produce agarase and alginate-lyase enzymatic activities. Our strain INACH002 was identified as a member of the genus Flavobacterium, closely related to Flavobacterium faecale, using 16S rRNA gene analysis. The INACH002 strain was characterized as psychrotrophic due to its optimal temperature (17ºC and maximum temperature (20°C of growth. Agarase and alginate-lyase displayed enzymatic activities within a range of 10°C to 50°C, with differences in the optimal temperature to hydrolyze agar (50°C, agarose (50°C and alginate (30°C during the first 30 min of activity. Strain Flavobacterium INACH002 is a promising Antarctic biotechnological resource; however, further research is required to illustrate the structural and functional bases of the enzymatic performance observed during the degradation of different substrates at different temperatures.

Targeting sphingosine-1-phosphate lyase as an anabolic therapy for bone loss.

Science.gov (United States)

Weske, Sarah; Vaidya, Mithila; Reese, Alina; von Wnuck Lipinski, Karin; Keul, Petra; Bayer, Julia K; Fischer, Jens W; Flögel, Ulrich; Nelsen, Jens; Epple, Matthias; Scatena, Marta; Schwedhelm, Edzard; Dörr, Marcus; Völzke, Henry; Moritz, Eileen; Hannemann, Anke; Rauch, Bernhard H; Gräler, Markus H; Heusch, Gerd; Levkau, Bodo

2018-05-01

Sphingosine-1-phosphate (S1P) signaling influences bone metabolism, but its therapeutic potential in bone disorders has remained unexplored. We show that raising S1P levels in adult mice through conditionally deleting or pharmacologically inhibiting S1P lyase, the sole enzyme responsible for irreversibly degrading S1P, markedly increased bone formation, mass and strength and substantially decreased white adipose tissue. S1P signaling through S1P 2 potently stimulated osteoblastogenesis at the expense of adipogenesis by inversely regulating osterix and PPAR-γ, and it simultaneously inhibited osteoclastogenesis by inducing osteoprotegerin through newly discovered p38-GSK3β-β-catenin and WNT5A-LRP5 pathways. Accordingly, S1P 2 -deficient mice were osteopenic and obese. In ovariectomy-induced osteopenia, S1P lyase inhibition was as effective as intermittent parathyroid hormone (iPTH) treatment in increasing bone mass and was superior to iPTH in enhancing bone strength. Furthermore, lyase inhibition in mice successfully corrected severe genetic osteoporosis caused by osteoprotegerin deficiency. Human data from 4,091 participants of the SHIP-Trend population-based study revealed a positive association between serum levels of S1P and bone formation markers, but not resorption markers. Furthermore, serum S1P levels were positively associated with serum calcium , negatively with PTH , and curvilinearly with body mass index. Bone stiffness, as determined through quantitative ultrasound, was inversely related to levels of both S1P and the bone formation marker PINP, suggesting that S1P stimulates osteoanabolic activity to counteract decreasing bone quality. S1P-based drugs should be considered as a promising therapeutic avenue for the treatment of osteoporotic diseases.

Fundamentals of phosphors

CERN Document Server

Yen, William M; Yamamoto, Hajime

2006-01-01

Drawing from the second edition of the best-selling Handbook of Phosphors, Fundamentals of Phosphors covers the principles and mechanisms of luminescence in detail and surveys the primary phosphor materials as well as their optical properties. The book addresses cutting-edge developments in phosphor science and technology including oxynitride phosphors and the impact of lanthanide level location on phosphor performance.Beginning with an explanation of the physics underlying luminescence mechanisms in solids, the book goes on to interpret various luminescence phenomena in inorganic and organic materials. This includes the interpretation of the luminescence of recently developed low-dimensional systems, such as quantum wells and dots. The book also discusses the excitation mechanisms by cathode-ray and ionizing radiation and by electric fields to produce electroluminescence. The book classifies phosphor materials according to the type of luminescence centers employed or the class of host materials used and inte...

Prenatal diagnosis in adenylosuccinate lyase deficiency

NARCIS (Netherlands)

Marie, S.; Flipsen, J. W.; Duran, M.; Poll-The, B. T.; Beemer, F. A.; Bosschaart, A. N.; Vincent, M. F.; van den Berghe, G.

2000-01-01

Adenylosuccinate lyase deficiency, an autosomal recessive inborn error of purine synthesis, provokes accumulation in body fluids of succinylaminoimidazolecarboxamide riboside and succinyladenosine, the dephosphorylated derivatives of the two substrates of the enzyme. Most patients display severe

Photoluminescent properties of Y2O3:Eu3+ phosphors prepared via urea precipitation in non-aqueous solution

International Nuclear Information System (INIS)

Sun, Y.; Qi, L.; Lee, M.; Lee, B.I.; Samuels, W.D.; Exarhos, G.J.

2004-01-01

Europium-doped yttrium oxide phosphors were obtained by firing precursors prepared by urea precipitation in ethanol and ethylenediamine. The precipitation in non-aqueous solution was carried out in an autoclave at 150 deg. C to allow the decomposition of urea. The photoluminescent intensities of the phosphors prepared in ethanol and ethylenediamine increased by about 30% compared to that of the phosphor prepared by the conventional urea homogeneous precipitation in aqueous solution. Amorphous carbonates and amorphous hydroxides/carbonates mixtures were identified as precursors from ethanol and ethylenediamine, respectively. The morphology and particle size were studied by SEM and dynamic laser scattering method

Production and Purification of a Novel Xanthan Lyase from a Xanthan-Degrading Microbacterium sp. Strain XT11

Directory of Open Access Journals (Sweden)

Fan Yang

2014-01-01

Full Text Available A xanthan lyase was produced and purified from the culture supernatant of an excellent xanthan-modifying strain Microbacterium sp. XT11. Xanthan lyase was induced by xanthan but was inhibited by its structural monomer glucose. Its production by strain XT11 is much higher than that by all other reported strains. The purified xanthan lyase has a molecular mass of 110 kDa and a specific activity of 28.2 U/mg that was much higher than that of both Paenibacillus and Bacillus lyases. It was specific on the pyruvated mannosyl residue in the intact xanthan molecule, but about 50% lyase activity remained when xanthan was partially depyruvated. Xanthan lyase was optimally active at pH 6.0–6.5 and 40°C and alkali-tolerant at a high pH value of 11.0. The metal ions including K+, Ca2+, Na+, Mg2+, Mn2+, and Li+ strongly stimulated xanthan lyase activity but ions Zn2+ and Cu2+ were its inhibitor. Xanthan lyase should be a novel enzyme different from the other xanthan lyases ever reported.

Phosphoketolase pathway contributes to carbon metabolism in cyanobacteria.

Science.gov (United States)

Xiong, Wei; Lee, Tai-Chi; Rommelfanger, Sarah; Gjersing, Erica; Cano, Melissa; Maness, Pin-Ching; Ghirardi, Maria; Yu, Jianping

2015-12-07

Central carbon metabolism in cyanobacteria comprises the Calvin-Benson-Bassham (CBB) cycle, glycolysis, the pentose phosphate (PP) pathway and the tricarboxylic acid (TCA) cycle. Redundancy in this complex metabolic network renders the rational engineering of cyanobacterial metabolism for the generation of biomass, biofuels and chemicals a challenge. Here we report the presence of a functional phosphoketolase pathway, which splits xylulose-5-phosphate (or fructose-6-phosphate) to acetate precursor acetyl phosphate, in an engineered strain of the model cyanobacterium Synechocystis (ΔglgC/xylAB), in which glycogen synthesis is blocked, and xylose catabolism enabled through the introduction of xylose isomerase and xylulokinase. We show that this mutant strain is able to metabolise xylose to acetate on nitrogen starvation. To see whether acetate production in the mutant is linked to the activity of phosphoketolase, we disrupted a putative phosphoketolase gene (slr0453) in the ΔglgC/xylAB strain, and monitored metabolic flux using (13)C labelling; acetate and 2-oxoglutarate production was reduced in the light. A metabolic flux analysis, based on isotopic data, suggests that the phosphoketolase pathway metabolises over 30% of the carbon consumed by ΔglgC/xylAB during photomixotrophic growth on xylose and CO2. Disruption of the putative phosphoketolase gene in wild-type Synechocystis also led to a deficiency in acetate production in the dark, indicative of a contribution of the phosphoketolase pathway to heterotrophic metabolism. We suggest that the phosphoketolase pathway, previously uncharacterized in photosynthetic organisms, confers flexibility in energy and carbon metabolism in cyanobacteria, and could be exploited to increase the efficiency of cyanobacterial carbon metabolism and photosynthetic productivity.

Utilization of Aspergillus oryzae to produce pectin lyase from various agro-industrial residues

OpenAIRE

Koser, Safia; Anwar, Zahid; Iqbal, Zafar; Anjum, Awais; Aqil, Tahir; Mehmood, Sajid; Irshad, Muhammad

2014-01-01

The present study was aimed to investigate the culture influence on pectin lyase production potential of fungal strain Aspergillus oryzae. The enzyme profile of A. oryzae showed highest activity of pectin lyase after 3rd day of incubation on lemon peel waste under solid state fermentation conditions. To induce the pectin lyase synthesis capability of A. oryzae at optimal level various culture variables including physical and nutritional parameters were optimized by adopting classical optimiza...

Transition pathways for a UK low carbon electricity future

International Nuclear Information System (INIS)

Foxon, Timothy J.

2013-01-01

Achieving long-term targets for greenhouse gas emissions reductions, such as the UK's legally-binding target of reducing its emissions by 80% by 2050, will require a transition in systems for meeting and shaping energy service demands, involving radical substitution to low-carbon supply technologies and improvements in end-use energy efficiency. This paper describes the development and high-level analysis of a set of transition pathways to a UK low carbon electricity system, explaining key features of the core pathways developed and the distinctiveness and value of the approach. The pathways use an ‘action space’ concept to explore the dynamic interactions between choices made by actors, which are influenced by the competing governance ‘framings’ or ‘logics’ that different actors pursue. The paper sets out three core transition pathways – Market Rules, Central Co-ordination and Thousand Flowers, in which market, government and civil society logics respectively dominate. It summarises the key technological and institutional changes in these pathways, and the roles of actors in bringing these about. This leads to an identification of the key risks to the realisation of each of the pathways, and of the challenges for individuals, businesses, social movements and policy-makers in taking action to bring them about and sustain them. - Highlights: ► Development of a set of transition pathways to a UK low carbon electricity system. ► Action space to explore the dynamic interactions between choices made by actors. ► Three core pathways in which market, government and civil society logics dominate. ► Key technological and institutional changes, and the roles of actors in pathways. ► Challenges for different actors in realising pathways.

Practical applications of phosphors

CERN Document Server

Yen, William M; Yamamoto, Hajime

2006-01-01

Drawn from the second edition of the best-selling Phosphor Handbook, Practical Applications of Phosphors outlines methods for the production of various phosphors and discusses a broad spectrum of applications. Beginning with methods for synthesis and related technologies, the book sets the stage by classifying and then explaining practical phosphors according to usage. It describes the operating principle and structure of phosphor devices and the phosphor characteristics required for a given device, then covers the manufacturing processes and characteristics of phosphors. The book discusses research and development currently under way on phosphors with potential for practical usage and touches briefly on phosphors that have played a historical role, but are no longer of practical use. It provides a comprehensive treatment of applications including lamps and cathode-ray tubes, x-ray and ionizing radiation, and for vacuum fluorescent and field emission displays and covers inorganic and organic electroluminescen...

Thermoluminescent phosphor

Science.gov (United States)

Lasky, Jerome B.; Moran, Paul R.

1978-01-01

A thermoluminescent phosphor comprising LiF doped with boron and magnesium is produced by diffusion of boron into a conventional LiF phosphor doped with magnesium. Where the boron dopant is made to penetrate only the outer layer of the phosphor, it can be used to detect shallowly penetrating radiation such as tritium beta rays in the presence of a background of more penetrating radiation.

Rare earth phosphors and phosphor screens

International Nuclear Information System (INIS)

Buchanan, R.A.; Maple, T.G.; Sklensky, A.F.

1981-01-01

Advances in the use of stabilized rare earth phosphors and of conversion screens using these materials are examined. In particular the new phosphors discussed in this invention consist of oxybromides of yttrium, lanthanum and gadolinium with a luminescent activator ion stabilized by an oxychloride or oxyfluoride surface layer and the conversion screens include trivalent cerium as the activator ion. (U.K.)

A novel gene encoding xanthan lyase of Paenibacillus alginolyticus strain XL-1

NARCIS (Netherlands)

Ruijssenaars, H.J.; Hartmans, S.; Verdoes, J.C.

2000-01-01

Xanthan-modifying enzymes are powerful tools in studying structure-function relationships of this polysaccharide. One of these modifying enzymes is xanthan lyase, which removes the terminal side chain residue of xanthan. In this paper, the cloning and sequencing of the first xanthan lyase-encoding

Crystallization and preliminary X-ray analysis of βC–S lyases from two oral streptococci

International Nuclear Information System (INIS)

Kezuka, Yuichiro; Yoshida, Yasuo; Nonaka, Takamasa

2009-01-01

The βC-S lyases from two oral bacteria, Streptococcus anginosus and S. gordonii, were cloned, overproduced, purified and crystallized. The obtained crystals were characterized by X-ray diffraction. Hydrogen sulfide, which causes oral malodour, is generally produced from l-cysteine by the action of βC–S lyase from oral bacteria. The βC–S lyases from two oral bacteria, Streptococcus anginosus and S. gordonii, have been cloned, overproduced, purified and crystallized. X-ray diffraction data were collected from the two types of crystals using synchrotron radiation. The crystal of S. anginosus βC–S lyase belonged to the orthorhombic space group P2 1 2 1 2 1 , with unit-cell parameters a = 67.0, b = 111.1, c = 216.4 Å, and the crystal of S. gordonii βC–S lyase belonged to the same space group, with unit-cell parameters a = 58.0, b = 73.9. c = 187.6 Å. The structures of the βC–S lyases were solved by molecular-replacement techniques

PecS and PecT coregulate the synthesis of HrpN and pectate lyases, two virulence determinants in Erwinia chrysanthemi 3937.

Science.gov (United States)

Nasser, William; Reverchon, Sylvie; Vedel, Regine; Boccara, Martine

2005-11-01

Erwinia chrysanthemi strain 3937 is a necrotrophic bacterial plant pathogen. Pectinolytic enzymes and, in particular, pectate lyases play a key role in soft rot symptoms; however, the efficient colonization of plants by E. chrysanthemi requires additional factors. These factors include HrpN (harpin), a heat-stable, glycine-rich hydrophilic protein, which is secreted by the type III secretion system. We investigated the expression of hrpN in E. chrysanthemi 3937 in various environmental conditions and different regulatory backgrounds. Using lacZ fusions, hrpN expression was markedly influenced by the carbon source, osmolarity, growth phase, and growth substrate. hrpN was repressed when pectinolysis started and negatively regulated by the repressors of pectate lyase synthesis, PecS and PecT. Primer extension data and in vitro DNA-protein interaction experiments support a model whereby PecS represses hrpN expression by binding to the hrpN regulatory region and inhibiting transcript elongation. The results suggest coordinated regulation of HrpN and pectate lyases by PecS and PecT. A putative model of the synthesis of these two virulence factors in E. chrysanthemi during pathogenesis is presented.

Chemical process for recovery of uranium values contained in phosphoric mineral lixivia

International Nuclear Information System (INIS)

Conceicao, E.L.H. da; Awwal, M.A.; Coelho, S. V.

1980-01-01

A recovery process of uranium values from phosporic mineral lixivia for obtaining uranio oxide concentrate adjusted to specifications of purity for its commercialization the process consists of the adjustment of electromotive force of lixiviem to suitable values for uranium extraction, extraction with organic solvent containing phosphoric acid ester and oxidant reextraction from this solvent with phosphoric acid solution, suggesting a new solvent extraction containing synergetic mixture of di-2-ethyl hexyl phosphoric acid and tri-octyl phosphine, leaching this solvent with water and re-extraction/precipitation with ammonium carbonate solution, resulting in the formation of uranyl tricarbonate and ammonium, that by drying and calcination gives the uranium oxide with purity degree for commercialization. (M.C.K.) [pt

Reduced phenylalanine ammonia-lyase and tyrosine ammonia-lyase activities and lignin synthesis in wheat grown under low pressure sodium lamps

Science.gov (United States)

Guerra, D.; Anderson, A. J.; Salisbury, F. B.

1985-01-01

Wheat (Triticum aestivum L. cv Fremont) grown in hydroponic culture under 24-hour continuous irradiation at 560 to 580 micromoles per square meter per second from either metalhalide (MH), high pressure sodium (HPS), or low pressure sodium (LPS) lamps reached maturity in 70 days. Grain yields were similar under all three lamps, although LPS-grown plants lodged at maturity. Phenylalanine ammonia-lyase (PAL) and a tyrosine ammonia lyase (TAL) with lesser activity were detected in all extracts of leaf, inflorescence, and stem. Ammonia-lyase activities increased with age of the plant, and plants grown under the LPS lamp displayed PAL and TAL activities lower than wheat cultured under MH and HPS radiation. Greenhouse solar-grown wheat had the highest PAL and TAL activities. Lignin content of LPS-grown wheat was also significantly reduced from that of plants grown under MH or HPS lamps or in the greenhouse, showing a correlation with the reduced PAL and TAL activities. Ratios of far red-absorbing phytochrome to total phytochrome were similar for all three lamps, but the data do not yet warrant a conclusion about specific wavelengths missing from the LPS lamps that might have induced PAL and TAL activities in plants under the other lamps.

Phosphoric acid fuel cell R and D activities at KACST

International Nuclear Information System (INIS)

Ghouse, M.; Aba-Oud, H.; Ba-Junaid, M.; Al-Garni, M.; Quadri, M.I.

1993-01-01

The PAFC (Phosphoric Acid Fuel Cell) activities are directed towards the development of components of single cell and experimental stacks at KACST. The main aim of the present task is to design and construct a 1 kW PAFC Stack and demonstrate it by integrating with an electrolyser using a DC current generated by a photovoltaic power source. This paper describes the preparation of porous teflon bonded gas diffusion carbon electrodes and their evaluation as single phosphoric acid fuel cells using hydrogen as a fuel and oxygen/air as an oxidant. 6 figs., 2 tabs., 15 refs

Transitions in pathways of human development and carbon emissions

International Nuclear Information System (INIS)

Lamb, W F; Bows-Larkin, A; Wood, F R; Steinberger, J K; Peters, G P; Roberts, J T

2014-01-01

Countries are known to follow diverse pathways of life expectancy and carbon emissions, but little is known about factors driving these dynamics. In this letter we estimate the cross-sectional economic, demographic and geographic drivers of consumption-based carbon emissions. Using clustering techniques, countries are grouped according to their drivers, and analysed with respect to a criteria of one tonne of carbon emissions per capita and a life expectancy over 70 years (Goldemberg’s Corner). Five clusters of countries are identified with distinct drivers and highly differentiated outcomes of life expectancy and carbon emissions. Representatives from four clusters intersect within Goldemberg’s Corner, suggesting diverse combinations of drivers may still lead to sustainable outcomes, presenting many countries with an opportunity to follow a pathway towards low-carbon human development. By contrast, within Goldemberg’s Corner, there are no countries from the core, wealthy consuming nations. These results reaffirm the need to address economic inequalities within international agreements for climate mitigation, but acknowledge plausible and accessible examples of low-carbon human development for countries that share similar underlying drivers of carbon emissions. In addition, we note differences in drivers between models of territorial and consumption-based carbon emissions, and discuss interesting exceptions to the drivers-based cluster analysis. (paper)

Production of endo-pectate lyase by two stage cultivation of Erwinia carotovora

Energy Technology Data Exchange (ETDEWEB)

Fukuoka, Satoshi; Kobayashi, Yoshiaki

1987-02-26

The productivity of endo-pectate lyase from Erwinia carotovora GIR 1044 was found to be greatly improved by two stage cultivation: in the first stage the bacterium was grown with an inducing carbon source, e.g., pectin, and in the second stage it was cultivated with glycerol, xylose, or fructose with the addition of monosodium L-glutamate as nitrogen source. In the two stage cultivation using pectin or glycerol as the carbon source the enzyme activity reached 400 units/ml, almost 3 times as much as that of one stage cultivation in a 10 liter fermentor. Using two stage cultivation in the 200 liter fermentor improved enzyme productivity over that in the 10 liter fermentor, with 500 units/ml of activity. Compared with the cultivation in Erlenmeyer flasks, fermentor cultivation improved enzyme productivity. The optimum cultivating conditions were agitation of 480 rpm with aeration of 0.5 vvm at 28 /sup 0/C. (4 figs, 4 tabs, 14 refs)

Phenylalanine ammonia-lyase through evolution: A bioinformatic approach

Directory of Open Access Journals (Sweden)

Shiva Hemmati

2015-03-01

Full Text Available Phenylalanine ammonia-lyase (PAL is the first entry enzyme of the phenylpropanoid pathway that converts phenylalanine to cinnamic acid which is the precursor of various secondary metabolites. PAL is recently formulated for phenylketonuric patients in pegylated forms; therefore, screening a PAL with the highest affinity to the substrate is of a great importance. PAL exists in all higher plants and some fungi and few bacteria. Ancestors of land plants have been adopted by evolving metabolic pathways. A multi-gene family encodes PAL by gene duplication events in most plants. In this study, the taxonomic distribution and phylogeny of pal gene found in land plants, fungi and bacteria have been analyzed. It seems that the ancestor of plants acquired a pal gene via horizontal gene transfer in symbioses with bacteria and fungi. Gymnosperms have kept a diverse set of pal genes that arose from gene duplication events. In angiosperms, after the divergence of dicotyledons from monocots, pal genes were duplicated many times. The close paralogues of pal genes in some species indicate expansion of gene families after the divergence in plant pal gene evolution. Interestingly, some of the plant pals clustered by species in a way that pals within one species are more closely related to each other than to homologs in the other species which indicates this duplication event occurred more recently.

Process for recovery of uranium from wet process phosphoric acid

International Nuclear Information System (INIS)

Wiewiorowski, T.K.; Thornsberry, W.L. Jr.

1978-01-01

Process is claimed for the recovery of uranium from wet process phosphoric acid solution in which an organic extractant, containing uranium values and dissolved iron impurities and comprising a dialkylphosphoric acid and a trialkylphosphine oxide dissolved in a water immiscible organic solvent, is contacted with a substantially iron-free dilute aqueous phosphoric acid to remove said iron impurities. The removed impurities are bled from the system by feeding the resulting iron-loaded phosphoric acid to a secondary countercurrent uranium extraction operation from which they leave as part of the uranium-depleted acid raffinate. Also, process for recovering uranium in which the extractant, after it has been stripped of uranium values by aqueous ammonium carbonate, is contacted with a dilute aqueous acid selected from the group consisting of H 2 SO 4 , HCl, HNO 3 and iron-free H 3 PO 4 to improve the extraction efficiency of the organic extractant

Oxidizer in phosphoric reactors

International Nuclear Information System (INIS)

Santos Benedetto, J. dos

1985-01-01

Oxidation during the manufacture of wet-process phosphoric acid affected the distribution of uranium and impurities between phosphoric acid and gypsum, by decreasing the uranium loss to gypsum and the impurities solubilization in phosphoric acid. (Author) [pt

Phosphors for LED lamps

Science.gov (United States)

Murphy, James Edward; Manepalli, Satya Kishore; Kumar, Prasanth Nammalwar

2013-08-13

A phosphor, a phosphor blend including the phosphor, a phosphor prepared by a process, and a lighting apparatus including the phosphor blend are disclosed. The phosphor has the formula (Ca.sub.1-p-qCe.sub.pK.sub.q).sub.xSc.sub.y(Si.sub.1-rGa.sub.r).sub.zO.su- b.12+.delta. or derived from a process followed using disclosed amounts of reactants. In the formula, (0

Extraction of uranium from phosphoric-hydrobromic acid mixture by N-lauryl tri alkyl methylamine

Energy Technology Data Exchange (ETDEWEB)

Guirguis, L A [Nuclear materials authority, Cairo, (Egypt); Tadros, N A [Hot laboratories center, atomic energy authority, Cairo, (Egypt)

1995-10-01

A uranium recovery process from phosphoric acid produced by the dihydrate method was elaborated. Decomposition of phosphate rock containing 0.02% U is carried out with sulphuric acid. Crude phosphoric acid is filtered off, steam concentrated to 45% P{sub 2} O{sub 5} (6.27 M) and then clarified with activated clay and carbon. The clear phosphoric acid is introduced to uranium extraction after the addition of 0.88 M hydrobromic acid by 0.134 M amberlite LA.2 and 5% decanol, as a modifier, in kerosene. While 10% ammonium sulphate solution is used for stripping. Over 90% uranium recovery is obtained. 6 figs., 1 tab.

Dependency of climate change and carbon cycle on CO2 emission pathways

International Nuclear Information System (INIS)

Nohara, Daisuke; Yoshida, Yoshikatsu; Misumi, Kazuhiro; Ohba, Masamichi

2013-01-01

Previous research has indicated that the response of globally average temperature is approximately proportional to cumulative CO 2 emissions, yet evidence of the robustness of this relationship over a range of CO 2 emission pathways is lacking. To address this, we evaluate the dependency of climate and carbon cycle change on CO 2 emission pathways using a fully coupled climate–carbon cycle model. We design five idealized pathways (including an overshoot scenario for cumulative emissions), each of which levels off to final cumulative emissions of 2000 GtC. The cumulative emissions of the overshoot scenario reach 4000 GtC temporarily, subsequently reducing to 2000 GtC as a result of continuous negative emissions. Although we find that responses of climatic variables and the carbon cycle are largely independent of emission pathways, a much weakened Atlantic meridional overturning circulation (AMOC) is projected in the overshoot scenario despite cessation of emissions. This weakened AMOC is enhanced by rapid warming in the Arctic region due to considerable temporary elevation of atmospheric CO 2 concentration and induces the decline of surface air temperature and decrease of precipitation over the northern Atlantic and Europe region. Moreover, the weakened AMOC reduces CO 2 uptake by the Atlantic and Arctic oceans. However, the weakened AMOC contributes little to the global carbon cycle. In conclusion, although climate variations have been found to be dependent on emission pathways, the global carbon cycle is relatively independent of these emission pathways, at least superficially. (letter)

Phosphor scintillator structure

International Nuclear Information System (INIS)

Cusano, D.A.; Prener, J.S.

1980-01-01

A method of fabricating scintillators is described in which the phosphor is distributed within the structure in such a way as to enhance the escape of the visible wavelength radiation that would otherwise be dissipated within the scintillator body. Two embodiments of the present invention are disclosed: one in which the phosphor is distributed in a layered structure and another in which the phosphor is dispersed throughout a transparent matrix. (U.K.)

[Construction and high-density fermentation of alkaline pectate lyase high-yield yeast].

Science.gov (United States)

Wang, Xiaowen; Xiang, La; Xu, Ting; Lu, Zhenghui; Zhang, Guimin

2017-12-25

Pectate lyase is widely applied in ramie degumming and fabric bioscouring in the textile industry. Compared to conventional processes that involve high alkaline and high temperature treatment, enzyme based treatments have significant advantages in fibers protectiveness, improved efficiency of refining, reduced energy consumption and pollution. Hence, it would be highly desirable to construct high-yield alkaline pectate lyase engineered strains and reduce the pectate lyase production cost. In the previous study, pectate lyase gene pel from Bacillus subtilis168 was expressed in Pichia pastoris GS115 after codon usage optimization based on the vector pHBM905A. To improve the expression level, the vector pHBM905BDM with optimized promoter and signal peptide was used to express the optimized gene pels in GS115. The transformant had increased activity from 68 U/mL to 100 U/mL with the improvement in the transcription level by 27% measured by qPCR. The transformants were further screened on pectin plates, where higher halo forming strains were picked for shake-flask fermentation and strain GS115-pHBM905BDM-pels4 showed the highest activity of 536 U/mL. Then plasmid pPIC9K-pels was constructed and electroporated into the GS115-pHBM905BDM-pels4 cells. Subsequently, high-copy transformant was screened by using the medium containing antibiotics G418, strain GS115-pHBM905BDMpPIC9K- pels1 was identified with increased activity of 770 U/mL and the copy number of pels was 7 confirmed by qPCR. Finally, the activity of pectate lyase produced by GS115-pHBM905BDM-pPIC9K-pels1reached to 2 271 U/mL in a 5-L fermentor. The activity of pectate lyase in our study reached the highest level of expression in P. pastoris, showing good application potential in the textile industry.

Diversity of function in the isocitrate lyase enzyme superfamily: the Dianthus caryophyllus petal death protein cleaves alpha-keto and alpha-hydroxycarboxylic acids.

Science.gov (United States)

Lu, Zhibing; Feng, Xiaohua; Song, Ling; Han, Ying; Kim, Alexander; Herzberg, Osnat; Woodson, William R; Martin, Brian M; Mariano, Patrick S; Dunaway-Mariano, Debra

2005-12-20

The work described in this paper was carried out to define the chemical function a new member of the isocitrate lyase enzyme family derived from the flowering plant Dianthus caryophyllus. This protein (Swiss-Prot entry Q05957) is synthesized in the senescent flower petals and is named the "petal death protein" or "PDP". On the basis of an analysis of the structural contexts of sequence markers common to the C-C bond lyases of the isocitrate lyase/phosphoenolpyruvate mutase superfamily, a substrate screen that employed a (2R)-malate core structure was designed. Accordingly, stereochemically defined C(2)- and C(3)-substituted malates were synthesized and tested as substrates for PDP-catalyzed cleavage of the C(2)-C(3) bond. The screen identified (2R)-ethyl, (3S)-methylmalate, and oxaloacetate [likely to bind as the hydrate, C(2)(OH)(2) gem-diol] as the most active substrates (for each, k(cat)/K(m) = 2 x 10(4) M(-)(1) s(-)(1)). In contrast to the stringent substrate specificities previously observed for the Escherichia coli isocitrate and 2-methylisocitrate lyases, the PDP tolerated hydrogen, methyl, and to a much lesser extent acetate substituents at the C(3) position (S configuration only) and hydoxyl, methyl, ethyl, propyl, and to a much lesser extent isobutyl substituents at C(2) (R configuration only). It is hypothesized that PDP functions in oxalate production in Ca(2+) sequestering and/or in carbon scavenging from alpha-hydroxycarboxylate catabolites during the biochemical transition accompanying petal senescence.

A Visual Detection System for Determining Tritium Surface Deposition Employing Phosphor Coated Materials

International Nuclear Information System (INIS)

Gentile, C.A.; Skinner, C.H.; Young, K.M.; Zweben, S.J.

1999-01-01

A method for visually observing tritium deposition on the surface of the Tokamak Fusion Test Reactor (TFTR) deuterium-tritium (D-T) tiles is being investigated at the Princeton Plasma Physics Laboratory. A green phosphor (P31, zinc sulfide: copper) similar to that used in oscilloscope screens with a wavelength peak of 530 nm was positioned on the surface of a TFTR D-T tile. The approximately 600 gram tile, which contains approximately 1.5 Ci of tritium located on the top approximately 1-50 microns of the surface, was placed in a two liter lexan chamber at Standard Temperature and Pressure (STP). The phosphor plates and phosphor powder were placed on the surface of the tile which resulted in visible light being observed, the consequence of tritium betas interacting with the phosphor. This technique provides a method of visually observing varying concentrations of tritium on the surface of D-T carbon tiles, and may be employed (in a calibrated system) to obtain quantitative data

Corrosion of graphite composites in phosphoric acid fuel cells

Science.gov (United States)

Christner, L. G.; Dhar, H. P.; Farooque, M.; Kush, A. K.

1986-01-01

Polymers, polymer-graphite composites and different carbon materials are being considered for many of the fuel cell stack components. Exposure to concentrated phosphoric acid in the fuel cell environment and to high anodic potential results in corrosion. Relative corrosion rates of these materials, failure modes, plausible mechanisms of corrosion and methods for improvement of these materials are investigated.

Uranium recovery from wet process phosphoric acid

International Nuclear Information System (INIS)

1980-01-01

In the field of metallurgy, specifically processes for recovering uranium from wet process phosphoric acid solution derived from the acidulation of uraniferous phosphate ores, problems of imbalance of ion exchange agents, contamination of recycled phosphoric acid with process organics and oxidizing agents, and loss and contamination of uranium product, are solved by removing organics from the raffinate after ion exchange conversion of uranium to uranous form and recovery thereof by ion exchange, and returning organics to the circuit to balance mono and disubstituted ester ion exchange agents; then oxidatively stripping uranium from the agent using hydrogen peroxide; then after ion exchange recovery of uranyl and scrubbing, stripping with sodium carbonate and acidifying the strip solution and using some of it for the scrubbing; regenerating the sodium loaded agent and recycling it to the uranous recovery step. Economic recovery of uranium as a by-product of phosphate fertilizer production is effected. (author)

Effect of Phosphoric Acid Concentration on the Characteristics of Sugarcane Bagasse Activated Carbon

Science.gov (United States)

Adib, M. R. M.; Suraya, W. M. S. W.; Rafidah, H.; Amirza, A. R. M.; Attahirah, M. H. M. N.; Hani, M. S. N. Q.; Adnan, M. S.

2016-07-01

Impregnation method is one of the crucial steps involved in producing activated carbon using chemical activation process. Chemicals employed in this step is effective at decomposing the structure of material and forming micropores that helps in adsorption of contaminants. This paper explains thorough procedures that have been involved in producing sugarcane bagasse activated carbon (SBAC) by using 5%, 10%, 20%, 30% phosphoric acid (H3PO4) during the impregnation step. Concentration of H3PO4 used in the process of producing SBAC was optimized through several tests including bulk density, ash content, iodine adsorption and pore size diameter and the charactesristic of optimum SBAC produced has been compared with commercial activated carbon (CAC). Batch study has been carried out by using the SBAC produced from optimum condition to investigate the performance of SBAC in removal of turbidity and chemical oxygen demand (COD) from textile wastewater. From characteristic study, SBAC with 30% H3PO4 has shown the optimum value of bulk density, ash content, iodine adsorption and pore size diameter of 0.3023 g cm-3, 4.35%, 974.96 mg/g and 0.21-0.41 µm, respectively. These values are comparable to the characteristics of CAC. Experimental result from the batch study has been concluded that the SBAC has a promising potential in removing turbidity and COD of 75.5% and 66.3%, respectively which was a slightly lower than CAC which were able to remove 82.8% of turbidity and 70% of COD. As a conclusion, the SBAC is comparable with CAC in terms of their characteristics and the capability of removing contaminants from textile wastewater. Therefore, it has a commercial value to be used as an alternative of low-cost material in producing CAC.

Process for recovering uranium from wet process phosphoric acid

International Nuclear Information System (INIS)

Pyrih, R.Z.; Rickard, S.; Carrington, F.

1982-01-01

A process for recovering uranium from phosphoric acid solutions uses an acidified alkali metal carbonate solution for the second-stage strip of uranyl uranium from the ion-exchange solution. The stripped solution is then recycled to the ion-exchange circuit. In the first stripping stage the ion-exchange solution containing the recovered uranyl uranium and an inert organic diluent is stripped with ammonium carbonate, producing a slurry of ammonium uranyl tricarbonate. The second strip, with a solution of 50-200 grams per litre of sodium carbonate eliminates the problems of inadequate removal of phosphorus, iron and vanadium impurities, solids accumulation, and phase separation in the strip circuit

Characterization of a Novel Alginate Lyase from Marine Bacterium Vibrio furnissii H1

Directory of Open Access Journals (Sweden)

Xiaoyan Zhu

2018-01-01

Full Text Available Alginate lyases show great potential for industrial and medicinal applications, especially as an attractive biocatalyst for the production of oligosaccharides with special bioactivities. A novel alginate lyase, AlyH1, from the marine bacterium Vibrio furnissii H1, which has been newly isolated from rotten seaweed, was purified and characterized. The purified enzyme showed the specific activity of 2.40 U/mg. Its molecular mass was 35.8 kDa. The optimal temperature and pH were 40 °C and pH 7.5, respectively. AlyH1 maintained stability at neutral pH (7.0–8.0 and temperatures below 30 °C. Metal ions Na+, Mg2+, and K+ increased the activity of the enzyme. With sodium alginate as the substrate, the Km and Vmax values of AlyH1 were 2.28 mg/mL and 2.81 U/mg, respectively. AlyH1 exhibited activities towards both polyguluronate and polymannuronate, and preferentially degraded polyguluronate. Products prepared from sodium alginate by AlyH1 were displayed to be di-, tri-, and tetra-alginate oligosaccharides. A partial amino acid sequence (190 aa of AlyH1 analysis suggested that AlyH1 was an alginate lyase of polysaccharide lyase family 7. The sequence showed less than 77% identity to the reported alginate lyases. These data demonstrated that AlyH1 could be as a novel and potential candidate in application of alginate oligosaccharides production with low polymerization degrees.

Quantitation of heparosan with heparin lyase III and spectrophotometry.

Science.gov (United States)

Huang, Haichan; Zhao, Yingying; Lv, Shencong; Zhong, Weihong; Zhang, Fuming; Linhardt, Robert J

2014-02-15

Heparosan is Escherichia coli K5 capsule polysaccharide, which is the key precursor for preparing bioengineered heparin. A rapid and effective quantitative method for detecting heparosan is important in the large-scale production of heparosan. Heparin lyase III (Hep III) effectively catalyzes the heparosan depolymerization, forming unsaturated disaccharides that are measurable using a spectrophotometer at 232 nm. We report a new method for the quantitative detection of heparosan with heparin lyase III and spectrophotometry that is safer and more specific than the traditional carbazole assay. In an optimized detection system, heparosan at a minimum concentration of 0.60 g/L in fermentation broth can be detected. Copyright © 2013 Elsevier Inc. All rights reserved.

Xylella fastidiosa esterase rather than hydroxynitrile lyase.

Science.gov (United States)

Torrelo, Guzman; Ribeiro de Souza, Fayene Zeferino; Carrilho, Emanuel; Hanefeld, Ulf

2015-03-02

In 2009, we reported that the product of the gene SCJ21.16 (XFa0032) from Xylella fastidiosa, a xylem-restricted plant pathogen that causes a range of diseases in several important crops, encodes a protein (XfHNL) with putative hydroxynitrile lyase activity. Sequence analysis and activity tests indicated that XfHNL exhibits an α/β-hydrolase fold and could be classified as a member of the family of FAD-independent HNLs. Here we provide a more detailed sequence analysis and new experimental data. Using pure heterologously expressed XfHNL we show that this enzyme cannot catalyse the cleavage/synthesis of mandelonitrile and that this protein is in fact a non-enantioselective esterase. Homology modelling and ligand docking simulations were used to study the active site and support these results. This finding could help elucidate the common ancestor of esterases and hydroxynitrile lyases with an α/β -hydrolase fold. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electron-beam-pumped phosphors

International Nuclear Information System (INIS)

Goldhar, J.; Krupke, W.F.

1985-01-01

Electron-beam excitation of solid-state scintillators, or phosphors, can result in efficient generation of visible light confined to relatively narrow regions of the spectrum. The conversion efficiency can exceed 20%, and, with proper choice of phosphors, radiation can be obtained anywhere from the near infrared (IR) to the near ultraviolet (UV). These properties qualify the phosphors as a potentially useful pump source for new solid-state lasers. New phosphors are being developed for high-brightness television tubes that are capable of higher power dissipation. Here, an epitaxial film of fluorescing material is grown on a crystalline substrate with good thermal properties. For example, researchers at North American Philips Laboratories have developed a cerium-doped yttrium aluminum garnet (YAG) grown on a YAG substrate, which has operated at 1 A/cm 2 at 20 kV without observed thermal quenching. The input power is higher by almost two orders of magnitude than that which can be tolerated by a conventional television phosphor. The authors describe tests of these new phosphors

High temperature thermometric phosphors

Science.gov (United States)

Allison, Stephen W.; Cates, Michael R.; Boatner, Lynn A.; Gillies, George T.

1999-03-23

A high temperature phosphor consists essentially of a material having the general formula LuPO.sub.4 :Dy.sub.(x),Eu.sub.y) wherein: 0.1 wt %.ltoreq.x.ltoreq.20 wt % and 0.1 wt %.ltoreq.y.ltoreq.20 wt %. The high temperature phosphor is in contact with an article whose temperature is to be determined. The article having the phosphor in contact with it is placed in the environment for which the temperature of the article is to be determined. The phosphor is excited by a laser causing the phosphor to fluoresce. The emission from the phosphor is optically focused into a beam-splitting mirror which separates the emission into two separate emissions, the emission caused by the dysprosium dopant and the emission caused by the europium dopent. The separated emissions are optically filtered and the intensities of the emission are detected and measured. The ratio of the intensity of each emission is determined and the temperature of the article is calculated from the ratio of the intensities of the separate emissions.

Catalytically important amino-acid residues of abalone alginate lyase HdAly assessed by site-directed mutagenesis

OpenAIRE

Yamamoto, Sayo; Sahara, Takehiko; Sato, Daisuke; Kawasaki, Kosei; Ohgiya, Satoru; Inoue, Akira; Ojima, Takao

2008-01-01

Alginate lyase is an enzyme that degrades alginate chains via β-elimination and has been used for the production of alginate oligosaccharides and protoplasts from brown algae. Previously, we deduced the amino-acid sequence of an abalone alginate lyase, HdAly, from its cDNA sequence and, through multiple amino-acid sequence alignment, found that several basic amino-acid residues were highly conserved among the polysaccharide-lyase family 14 (PL-14) enzymes including HdAly. In the present study...

Kinetic study of ion exchange in phosphoric acid chelating resin

International Nuclear Information System (INIS)

Brikci-Nigassa, Mounir; Hamouche, Hafida

1995-11-01

Uranium may be recovered as a by product of wet phosphoric acid using a method based on specific ion exchange resins. These resins called chelates contain amino-phosphonic functional groups. The resin studied in this work is a purolite S-940; uranium may be loaded on this resin from 30% P2O5 phosphoric acid in its reduced state. The influence of different parameters on the successive steps of the process have been studied in batch experiments: uranium reduction, loading and oxydation. Uranium may be eluted with ammonium carbonate and the resin regeneration may be done with hydrochloric acid.Ferric ions reduce the effective resin capacity considerably and inert fixation conditions are proposed to enhance uranium loading

Design of thermostable rhamnogalacturonan lyase mutants from Bacillus licheniformis by combination of targeted single point mutations

DEFF Research Database (Denmark)

da Silva, Ines Isabel Cardoso Rodrigues; Jers, Carsten; Otten, Harm

2014-01-01

Rhamnogalacturonan I lyases (RGI lyases) (EC 4.2.2.-) catalyze cleavage of α-1,4 bonds between rhamnose and galacturonic acid in the backbone of pectins by β-elimination. In the present study, targeted improvement of the thermostability of a PL family 11 RGI lyase from Bacillus licheniformis (DSM......, were obtained due to additive stabilizing effects of single amino acid mutations (E434L, G55V, and G326E) compared to the wild type. The crystal structure of the B. licheniformis wild-type RGI lyase was also determined; the structural analysis corroborated that especially mutation of charged amino...

A radiometric technique for the measurement of adenylosuccinate lyase

International Nuclear Information System (INIS)

Park, K.W.; Tyagi, A.K.; Cooney, D.A.

1980-01-01

When radioactive adenylosuccinic acid (AMP-S) is metabolized to AMP and fumaric acid by the enzyme adenylosuccinate lyase (EC 4.3.2.2), a proton is released to the solvent as 3 H 2 O. This removal is believed to be stereospecifically identical to that catalyzed by the enzyme, L-aspartase, and therefore entails the loss of a proton from C-3 of the dicarboxylic acid moiety of the nucleotide. Advantage has been taken of this fact in the design of a facile assay for this enzyme. The assay permits the simultaneous estimation of the lyase activity in a large battery of samples; it is not interfered with by opalescent or proteinaceous suspensions; it is accurate and outstandingly sensitive. (Auth.)

Alfalfa contains substantial 9-hydroperoxide lyase activity and a 3Z:2E-enal isomerase

NARCIS (Netherlands)

Vliegenthart, J.F.G.; Noordermeer, M.A.; Veldink, G.A.

1999-01-01

Fatty acid hydroperoxides formed by lipoxygenase can be cleaved by hydroperoxide lyase resulting in the formation of short-chain aldehydes and omega-oxo acids. Plant hydroperoxide lyases use 13- or 9-hydroperoxy linoleic and linolenic acid as substrates. Alfalfa (Medicago sativa L.) has been

Defect-Induced Luminescence of a Self-Activated Borophosphate Phosphor

Science.gov (United States)

Han, Bing; Liu, Beibei; Dai, Yazhou; Zhang, Jie

2018-05-01

A self-activated borophosphate phosphor Ba3BPO7 was prepared via typical solid-state reaction in thermal-carbon reduction atmosphere. The structural and luminescence properties were investigated using x-ray powder diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and photoluminescence spectroscopy. Upon excitation with ultraviolet (UV) light, the as-prepared phosphor shows bright greenish-yellow emission with a microsecond-level fluorescence lifetime, which could result from the oxygen vacancies produced in the process of solid-state synthesis. The possible luminescence mechanism is proposed. Through the introduction of defects in the host, this work realizes visible luminescence in a pure borophosphate compound that does not contain any rare earth or transition metal activators, so it is helpful to develop defect-related luminescent materials in view of energy conservation and environmental protection for sustainable development.

Inorganic-Organic hybrid materials for uranium extraction from phosphoric acid

International Nuclear Information System (INIS)

El-Mourabit, Sabah

2013-01-01

Phosphate rocks are industrially processed in large quantities to produce phosphoric acid and fertilisers. These rocks contain significant concentration of uranium (50 to 300 ppm) which could be interesting for nuclear industry. This work deals with the valorisation of uranium as a by-product from fertiliser industry. The aim of this study is to develop a hybrid material, constituted of an inorganic solid support grafted with an extractant (complexing molecule), which can extract selectively uranium from phosphoric acid medium. The first step of our approach was to identify an inorganic support which is stable under these particular conditions (strong acidity and complexing medium). The chemical and mechanical stability of different meso-porous materials, such as silica, glass and carbon was studied. In a second phase, we focused on the identification and the optimisation of complexing molecules, specific of uranium in phosphoric acid. These ligands were then grafted on the most stable solids. Finally, the efficiency of these hybrid systems was evaluated through different tests of extraction, selectivity and de-extraction. (author) [fr

Activities of methionine-γ-lyase in the acidophilic archaeon “Ferroplasma acidarmanus” strain fer1

Directory of Open Access Journals (Sweden)

Khan MA

2013-04-01

Full Text Available M A Khan,1 Madeline M López-Muñoz,2 Charles W Kaspar,3 Kai F Hung1 1Department of Biological Sciences, Eastern Illinois University, Charleston, IL, USA; 2Department of Biology, Universidad de Puerto Rico, Mayaguez, Puerto Rico; 3Bacteriology Department, University of Wisconsin, Madison, WI, USA Abstract: Biogeochemical processes on exposed pyrite ores result in extremely high levels of sulfuric acid at these locations. Acidophiles that thrive in these conditions must overcome significant challenges, including an environment with proton concentrations at pH 3 or below. The role of sulfur metabolism in the archaeon “Ferroplasma acidarmanus” strain fer1's ability to thrive in this environment was investigated due to its growth-dependent production of methanethiol, a volatile organic sulfur compound. Two putative sequences for methionine-γ-lyase (EC 4.4.1.11, an enzyme known to carry out α, γ-elimination on L-methionine to produce methanethiol, were identified in fer1. Bioinformatic analyses identified a conserved pyridoxal-5'-phosphate (PLP binding domain and a partially conserved catalytic domain in both putative sequences. Detection of PLP-dependent and L-methionine-dependent production of α-keto compounds and thiol groups in fer1 confirmed the presence of methionine-γ-lyase activity. Further, fer1 lysate was capable of processing related substrates, including D-methionine, L-cysteine, L-cystathionine, and L/D-homocysteine. When the two putative fer1 methionine-γ-lyase gene-coded proteins were expressed in Escherichia coli cells, one sequence demonstrated an ability to carry out α, γ-elimination activity, while the other exhibited γ-replacement activity. These fer1 methionine-γ-lyases also exhibited optimum pH, substrate specificity, and catalytic preferences that are different from methionine-γ-lyases from other organisms. These differences are discussed in the context of molecular phylogeny constructed using a maximum

Process for extracting uranium from phosphoric acid solutions

International Nuclear Information System (INIS)

1977-01-01

The description is given of a method for extracting uranium from phosphoric acid solutions whereby the previously oxided acid is treated with an organic solvent constituted by a mixture of dialkylphosphoric acid and trialkylphosphine oxide in solution in a non-reactive inert solvent so as to obtain de-uraniated phosphoric acid and an organic extract constituted by the solvent containing most of the uranium. The uranium is then separated from the extract as uranyl ammonium tricarbonate by reaction with ammonia and ammonium carbonate and the extract de-uraniated at the extraction stage is recycled. The extract is treated in a re-extraction apparatus comprising not less than two stages. The extract to be treated is injected at the top of the first stage. At the bottom of the first stage, ammonia is introduced counter current as gas or as an aqueous solution whilst controlling the pH of the first stage so as to keep it to 8.0 or 8.5 and at the bottom of the last stage an ammonium carbonate aqueous solution is injected in a quantity representing 50 to 80% of the stoichiometric quantity required to neutralize the dialkylphosphoric acid contained in the solvent and transform the uranium into uranyl ammonium tricarbonate [fr

The effect of cadmium on phenylalanine ammonia lyase activity and lipid peroxidation in pepper (Capsicum annuum L. seedlings

Directory of Open Access Journals (Sweden)

Esra Koç

2015-04-01

Full Text Available In this study, the effect on differrent concentrations (20, 40, 80µM ve 100 µM CdCl2 of cadmium (CdCl2 on the activity of phenylalanine ammonia-lyase (PAL and lipid peroxidation amount in leaf and stem of Kahramanmaraş- Hot (Capsicum annum L. pepper seedlings were researched. Activity of phenylalanine ammonia-lyase (PAL, the first enzyme in the phenylpropanoid biosynthetic pathway, was increased at 2 and 4 days in KM-Hot plants exposed to CdCl2 stress. The highest PAL activity was detected in 20 μM CdCl2 application, on the four day after the application in the leaves of KM-Hot pepper. Moreover, it was observed that treatment of pepper with Cd led to an increased the rate of lipid peroxidation (which is indicated by increasing MDA content in the leaf and stem tissues. The highest MDA content was detected in 80 μM CdCl2 application, on the four day after the application in the leaf tissues. These results suggest that the activation of PAL may be associated with increased production of MDA

The crystal structures of the tri-functional Chloroflexus aurantiacus and bi-functional Rhodobacter sphaeroides malyl-CoA lyases and comparison with CitE-like superfamily enzymes and malate synthases.

Science.gov (United States)

Zarzycki, Jan; Kerfeld, Cheryl A

2013-11-09

Malyl-CoA lyase (MCL) is a promiscuous carbon-carbon bond lyase that catalyzes the reversible cleavage of structurally related Coenzyme A (CoA) thioesters. This enzyme plays a crucial, multifunctional role in the 3-hydroxypropionate bi-cycle for autotrophic CO2 fixation in Chloroflexus aurantiacus. A second, phylogenetically distinct MCL from Rhodobacter sphaeroides is involved in the ethylmalonyl-CoA pathway for acetate assimilation. Both MCLs belong to the large superfamily of CitE-like enzymes, which includes the name-giving β-subunit of citrate lyase (CitE), malyl-CoA thioesterases and other enzymes of unknown physiological function. The CitE-like enzyme superfamily also bears sequence and structural resemblance to the malate synthases. All of these different enzymes share highly conserved catalytic residues, although they catalyze distinctly different reactions: C-C bond formation and cleavage, thioester hydrolysis, or both (the malate synthases). Here we report the first crystal structures of MCLs from two different phylogenetic subgroups in apo- and substrate-bound forms. Both the C. aurantiacus and the R. sphaeroides MCL contain elaborations on the canonical β8/α8 TIM barrel fold and form hexameric assemblies. Upon ligand binding, changes in the C-terminal domains of the MCLs result in closing of the active site, with the C-terminal domain of one monomer forming a lid over and contributing side chains to the active site of the adjacent monomer. The distinctive features of the two MCL subgroups were compared to known structures of other CitE-like superfamily enzymes and to malate synthases, providing insight into the structural subtleties that underlie the functional versatility of these enzymes. Although the C. aurantiacus and the R. sphaeroides MCLs have divergent primary structures (~37% identical), their tertiary and quaternary structures are very similar. It can be assumed that the C-C bond formation catalyzed by the MCLs occurs as proposed for

PREPARATION AND PROPERTIES OF ALKALI-ACTIVATED CEMENT CONTAINING PHOSPHOROUS SLAG AND FLY ASH

Directory of Open Access Journals (Sweden)

Duo You

2016-03-01

Full Text Available Phosphorous slag is an industrial waste which potentially pollutes environments. The aim of the present work is to use phosphorous slag as a raw material to produce alkali-activated cement. The influence of mix proportion of phosphorous slag and fly ash, alkali content and modulus of water glass on the properties of alkali-activated phosphorous slag and fly ash cement (AA-PS-FA-C was studied. The results show that AA-PS-FA-C with normal setting performance and desirable mechanical properties can be prepared using water glass as the activator. Changing the fly ash content in the range of 0-40 wt% has only a small influence on the setting time of AA-PS-FA-C. The strengths significantly decrease when the fly ash content exceeds 30 wt%. The carbonation resistance of AA-PS-FA-C is similar to that of ordinary Portland cement (OPC, while the frost resistance is much better. The hardened paste of AA-PS-FA-C is much more compact than OPC paste.

Hematopoietic Sphingosine 1-Phosphate Lyase Deficiency Decreases Atherosclerotic Lesion Development in LDL-Receptor Deficient Mice

NARCIS (Netherlands)

Bot, Martine; Van Veldhoven, Paul P.; de Jager, Saskia C. A.; Johnson, Jason; Nijstad, Niels; Van Santbrink, Peter J.; Westra, Marijke M.; Van Der Hoeven, Gerd; Gijbels, Marion J.; Mueller-Tidow, Carsten; Varga, Georg; Tietge, Uwe J. F.; Kuiper, Johan; Van Berkel, Theo J. C.; Nofer, Jerzy-Roch; Bot, Ilze; Biessen, Erik A. L.

2013-01-01

Aims: Altered sphingosine 1-phosphate (S1P) homeostasis and signaling is implicated in various inflammatory diseases including atherosclerosis. As S1P levels are tightly controlled by S1P lyase, we investigated the impact of hematopoietic S1P lyase (Sgpl1(-/-)) deficiency on leukocyte subsets

Hematopoietic sphingosine 1-phosphate lyase deficiency decreases atherosclerotic lesion development in LDL-receptor deficient mice

NARCIS (Netherlands)

Bot, Martine; van Veldhoven, Paul P.; de Jager, Saskia C. A.; Johnson, Jason; Nijstad, Niels; van Santbrink, Peter J.; Westra, Marijke M.; van der Hoeven, Gerd; Gijbels, Marion J.; Müller-Tidow, Carsten; Varga, Georg; Tietge, Uwe J. F.; Kuiper, Johan; van Berkel, Theo J. C.; Nofer, Jerzy-Roch; Bot, Ilze; Biessen, Erik A. L.

2013-01-01

Altered sphingosine 1-phosphate (S1P) homeostasis and signaling is implicated in various inflammatory diseases including atherosclerosis. As S1P levels are tightly controlled by S1P lyase, we investigated the impact of hematopoietic S1P lyase (Sgpl1(-/-)) deficiency on leukocyte subsets relevant to

Hematopoietic Sphingosine 1-Phosphate Lyase Deficiency Decreases Atherosclerotic Lesion Development in LDL-Receptor Deficient Mice

NARCIS (Netherlands)

Bot, M.; Veldhoven, van P.P.; Jager, de S.C.; Johnson, J.; Nijstad, N.; van, Santbrink P.J.; Westra, M.M.; Hoeven, van der G.; Gijbels, M.J.; Muller-Tidow, C.; Varga, G.; Tietge, U.J.; Kuiper, J.; Berkel, van T.J.; Nofer, J.R.; Bot, I.; Biessen, E.A.

2013-01-01

Abstract Aims Altered sphingosine 1-phosphate (S1P) homeostasis and signaling is implicated in various inflammatory diseases including atherosclerosis. As S1P levels are tightly controlled by S1P lyase, we investigated the impact of hematopoietic S1P lyase (Sgpl1−/−) deficiency on leukocyte

Branching points for transition pathways: assessing responses of actors to challenges on pathways to a low carbon future

International Nuclear Information System (INIS)

Foxon, Timothy J.; Pearson, Peter J.G.; Arapostathis, Stathis; Carlsson-Hyslop, Anna; Thornton, Judith

2013-01-01

This paper describes initial analysis of branching points on a set of transition pathways to a UK low carbon electricity future by 2050. As described in other papers in this special issue, we are exploring and analysing a set of core transition pathways, based on alternative governance patterns in which the ‘logics’ of market actors, government actors and civil society actors, respectively dominate. This core pathway analysis is enhanced by analyses of branching points within and across the pathways, which informs how competition between different logics plays out at key decision points. Branching points are defined as key decision points at which choices made by actors, in response to internal or external stresses or triggers, determine whether and in what ways the pathway is followed. A set of initial branching points for our three core transition pathways is identified through project and stakeholder workshops, and drawing on analysis of actors’ choices and responses at past branching points in energy system transitions. The potential responses of the actors are identified at these branching points, and risk mitigation strategies are formulated for the dominant actors to reinforce that pathway, as well as opportunities for actors to move away from the pathway. - Highlights: Transition Pathways is analysing three potential pathways to a low carbon future. ► Stresses lead to branching points, where actors make choices, creating pathways. ► These choices may lead to path-dependency. ► Differences in governance logics within transition pathways are also analysed. ► Studying branching points adds theoretical understanding and policy relevance to TP.

Molecular cloning, purification, and characterization of a novel polyMG-specific alginate lyase responsible for alginate MG block degradation in Stenotrophomas maltophilia KJ-2

Energy Technology Data Exchange (ETDEWEB)

Lee, Su In; Kim, Hee Sook [Kyungsung Univ., Busan (Korea, Republic of). Dept. of Food Science and Biotechnology; Choi, Sung Hee; Lee, Eun Yeol [Kyung Hee Univ., Gyeonggi-do (Korea, Republic of). Dept. of Chemical Engineering

2012-09-15

A gene for a polyMG-specific alginate lyase possessing a novel structure was identified and cloned from Stenotrophomas maltophilia KJ-2 by using PCR with homologous nucleotide sequences-based primers. The recombinant alginate lyase consisting of 475 amino acids was purified on Ni-Sepharose column and exhibited the highest activity at pH 8 and 40 C. Interestingly, the recombinant alginate lyase was expected to have a similar catalytic active site of chondroitin B lyase but did not show chondroitin lyase activity. In the test of substrate specificity, the recombinant alginate lyase preferentially degraded the glycosidic bond of polyMG-block than polyM-block and polyG-block. The chemical structures of the degraded alginate oligosaccharides were elucidated to have mannuronate (M) at the reducing end on the basis of NMR analysis, supporting that KJ-2 polyMG-specific alginate lyase preferably degraded the glycosidic bond in M-G linkage than that in G-M linkage. The KJ-2 polyMG-specific alginate lyase can be used in combination with other alginate lyases for a synergistic saccharification of alginate. (orig.)

Unactivated yttrium tantalate phosphor

International Nuclear Information System (INIS)

Reddy, V.B.; Cheung, H.K.

1992-01-01

This patent describes an unactivated yttrium tantalate phosphor having M prime monoclinic structure and containing one or more additives of Rb and Al in an amount of between about 0.001 to 0.1 moles per mole of yttrium tantalate to improve brightness under X-radiation. This patent also describes an unactivated yttrium tantalate phosphor having M prime monoclinic structure and containing additives of Sr in an amount of between 0.001 to 0.1 moles per mole of yttrium tantalate and one or more of Rb and Al in an amount of between 0.001 to 0.1 moles per mole of yttrium tantalate the phosphor exhibiting a greater brightness under X-radiation than the phosphor absent Rb and Al

Flexural Properties of Activated Carbon Filled Epoxy Nano composites

International Nuclear Information System (INIS)

Khalil, H.P.S.A.; Khalil, H.P.S.A.; Alothman, O.Y.; Paridah, M.T.; Zainudin, E.S.

2014-01-01

Activated carbon (AC) filled epoxy nano composites obtained by mixing the desired amount of nano AC viz., bamboo stem, oil palm empty fruit bunch, and coconut shell from agricultural biomass with the epoxy resin. Flexural properties of activated carbons filled epoxy nano composites with 1 %, and 5 % filler loading were measured. In terms of flexural strength and modulus, a significant increment was observed with addition of 1 % vol and 5 % vol nano-activated carbon as compared to neat epoxy. The effect of activated carbon treated by two chemical agents (potassium hydroxide and phosphoric acid) on the flexural properties of epoxy nano composites were also investigated. Flexural strength of activated carbon-bamboo stem, activated carbon-oil palm, and activated carbon-coconut shell reinforced epoxy nano composites showed almost same value in case of 5 % potassium hydroxide activated carbon. Flexural strength of potassium hydroxide activated carbon-based epoxy nano composites was higher than phosphoric acid activated carbon. The flexural toughness of both the potassium hydroxide and phosphoric acid activated carbon reinforced composites range between 0.79 - 0.92 J. It attributed that developed activated carbon filled epoxy nano composites can be used in different applications. (author)

Sequence analysis and overexpression of a pectin lyase gene (pel1) from Aspergillus oryzae KBN616.

Science.gov (United States)

Kitamoto, N; Yoshino-Yasuda, S; Ohmiya, K; Tsukagoshi, N

2001-01-01

A gene (pel1) encoding pectin lyase (Pel1) was isolated from a shoyu koji mold, Aspergillus oryzae KBN616, and characterized. The structural gene comprised 1,196 bp with a single intron. The ORF encoded 381 amino acids with a signal peptide of 20 amino acids. The deduced amino acid sequence showed high similarity to those of Aspergillus niger pectin lyases and Glomerella cingulata PnlA. The pel1 gene was successfully overexpressed under the promoter of the A. oryzae TEF1 gene. The molecular mass of the recombinant pectin lyase substantially coincided with that calculated based on nucleotide sequence.

Survey on aging on electrodes and electrocatalysts in phosphoric acid fuel cells

Science.gov (United States)

Stonehart, P.; Hochmuth, J.

1981-01-01

The processes which contribute to the decay in performance of electrodes used in phosphoric acid fuel cell systems are discussed. Loss of catalytic surface area, corrosion of the carbon support, electrode structure degradation, electrolyte degradation, and impurities in the reactant streams are identified as the major areas for concern.

Mechanistic deductions from kinetic isotope effects and pH studies of pyridoxal phosphate dependent carbon-carbon lyases: Erwinia herbicola and Citrobacter freundii tyrosine phenol-lyase

International Nuclear Information System (INIS)

Kiick, D.M.; Phillips, R.S.

1988-01-01

The pH dependence of the kinetic parameters and primary deuterium isotope effects have been determined for tyrosine phenol-lyase from both Erwinia herbicola and Citrobacter freundii. The primary deuterium isotope effects indicate that proton abstraction from the 2-position of the substrate is partially rate-limiting for both enzymes. The C. freundii enzyme primary deuterium isotope effects [DV = 3.5 and D(V/Ktyr) = 2.5] are pH independent, indicating that tyrosine is not sticky (i.e., does not dissociate slower than it reacts to give products). Since Vmax for both tyrosine and the alternate substrate S-methyl-L-cysteine is also pH independent, substrate binds only to the correctly protonated form of the enzyme. For the E. herbicola enzyme, both Vmax and V/K for tyrosine or S-methyl-L-cysteine are pH dependent, as well as both DV and D(V/Ktyr). Thus, while both the protonated and unprotonated enzyme can bind substrate, and may be interconverted directly, only the unprotonated Michaelis complex is catalytically competent. At pH 9.5, DV = 2.5 and D(V/Ktyr) = 1.5. However, at pH 6.4 the isotope effect on both parameters is equal to 4.1. From these data, the forward commitment factor (cf = 5.2) and catalytic ratio (cvf = 1.1) for tyrosine and S-methyl-L-cysteine (cf = 2.2, cvf = 24) are calculated. Also, the Michaelis complex partition ratio (cf/cvf) for substrate and products is calculated to be 4.7 for tyrosine and 0.1 for S-methyl-L-cysteine

Elimination of hydrogen sulphide and β substitution in cystein, catalyzed by the cysteine-lyase of hens yolk-sac and yolk (1961)

International Nuclear Information System (INIS)

Chapeville, F.; Fromageot, P.

1961-01-01

The yolk of incubated hen's eggs contains a pyridoxal phosphate activated enzyme, free of iron, copper, magnesium and calcium. This enzyme activates the β-carbon atom of cysteine. Its reactivity is demonstrated by the ease with which this β-carbon fixes various sulfur containing substances in which the sulfur has reducing properties: inorganic sulfide, sulfide or cysteine itself. In the absence of substances able to react with the β-carbon atom, the active complex, consisting of the enzyme and the aminated tri-carbon chain, is hydrolysed to pyruvic acid and ammonia. The liberation of hydrogen sulfide thus appears to be the consequence either of the substitution of the β-carbon atom of cysteine or of the decomposition of the complex which this aminoacid forms with the enzyme studied. The latter seems therefore to possess an activity which differs from the activity of the desulfhydrases as yet known. We suggest to call this enzyme cystein-lyase. (authors) [fr

White light quality of phosphor converted light-emitting diodes: A phosphor materials perspective of view

International Nuclear Information System (INIS)

Sommer, Christian; Hartmann, Paul; Pachler, Peter; Hoschopf, Hans; Wenzl, Franz P.

2012-01-01

Highlights: ► We discuss the impact of the optical properties of a phosphor for colour temperature constancy in solid state lighting. ► Quantitative evaluation of permissible variations of the optical properties for batch-to-batch reproducibility. ► Quantitative evaluation of permissible variations of the optical properties upon temperature increase. ► Quantitative evaluation of permissible variations of the optical properties upon materials degradation. - Abstract: For a systematic approach to improve the white light quality of phosphor converted LEDs and to fulfil the demands for colour temperature reproducibility and constancy, it is imperative to understand how variations of the extinction coefficient and the quantum efficiency of the phosphor particles as well as variations of the excitation wavelength of the blue LED die affect the correlated colour temperature of the white LED source. Based on optical ray tracing of a phosphor converted white LED package we deduce permissible values for the variation of a given extinction coefficient and a given quantum efficiency of a phosphor material in order to maintain acceptable colour variations. These quantitative valuations of the required constancy of the optical properties of the phosphors will in particular provide some benchmarks for the synthesis of improved phosphor materials aiming at solid state lighting applications.

Cloning and study of the pectate lyase gene of Erwinia carotovora

International Nuclear Information System (INIS)

Bukanov, N.O.; Fonshtein, M.Yu.; Evtushenkov, A.N.; Syarinskii, M.A.; Strel'chenko, P.P.; Yankovski, N.K.; Alikhanyan, S.I.; Fomichev, Yu.K.; Debabov, V.G.

1986-01-01

The cloning of the gene of a secretable protein of Erwinia carotovora, pectate lyase, in Escherichia coli was described. Primary cloning was conducted using the phage vector λ 47.1. In the gene library of E. carotovora obtained, eight phages carrying the gene sought were identified according to the appearance of enzymatic activity of the gene product, pectate lyase, in situ. The BamHI fragment of DNA, common to all these phages, was recloned on the plasmid pUC19. It was shown that the cloned pectate lyase gene is represented on the E. carotovora chromosome in one copy. Methods of production of representative gene libraries on phage vectors from no less than 1 μg of cloned DNA even for the genomes of eukaryotes have now been developed. Vectors have been created, for example, λ 47.1, permitting the selection only of hybrid molecules. A number of methods have been developed for the search for a required gene in the library, depending on whether the cloned gene can be expressed or not, and if it can, what properties it will impart to the hybrid clone containing it

Production of Odd-Carbon Dicarboxylic Acids in Escherichia coli Using an Engineered Biotin-Fatty Acid Biosynthetic Pathway.

Science.gov (United States)

Haushalter, Robert W; Phelan, Ryan M; Hoh, Kristina M; Su, Cindy; Wang, George; Baidoo, Edward E K; Keasling, Jay D

2017-04-05

Dicarboxylic acids are commodity chemicals used in the production of plastics, polyesters, nylons, fragrances, and medications. Bio-based routes to dicarboxylic acids are gaining attention due to environmental concerns about petroleum-based production of these compounds. Some industrial applications require dicarboxylic acids with specific carbon chain lengths, including odd-carbon species. Biosynthetic pathways involving cytochrome P450-catalyzed oxidation of fatty acids in yeast and bacteria have been reported, but these systems produce almost exclusively even-carbon species. Here we report a novel pathway to odd-carbon dicarboxylic acids directly from glucose in Escherichia coli by employing an engineered pathway combining enzymes from biotin and fatty acid synthesis. Optimization of the pathway will lead to industrial strains for the production of valuable odd-carbon diacids.

Phosphor investigation in the production of Syrian phosphoric acid using Nuclear Magnetic Resonance

International Nuclear Information System (INIS)

Al-Hassanieh, O.; Al-Hameish, M.

2009-06-01

Nuclear magnetic resonance spectroscopy (NMR) was applied in this work to the industrial process of extraction of uranium from phosphoric acid and to the process of the purification of the phosphoric acid for food proposes. The structural changes of used extraction materials and the organic content of the final product was studied. 13 C , 1 H and 32 P-spectra of all material during the process were recorded. The spectra of the three used extraction materials Bis(2-ethylhexyl Phosphoric Acid)) DEHPA, TriOctyl Phosphine Oxide (TOPO) (C 8 H 1 7) 3 P=O and TriButyl Phosphate (TBP) (C 4 H 9 O) 3 P=O show a partial degradation during the process. The final product ( Phosphoric acid for Food proposes) doesn't contain any organic solvents or extraction material. (author)

Radioluminescent nuclear batteries with different phosphor layers

International Nuclear Information System (INIS)

Hong, Liang; Tang, Xiao-Bin; Xu, Zhi-Heng; Liu, Yun-Peng; Chen, Da

2014-01-01

Highlights: • We present and test the electrical properties of the nuclear battery. • The best thickness range for ZnS:Cu phosphor layer is 12–14 mg cm −2 for 147 Pm radioisotope. • The best thickness range for Y 2 O 2 S:Eu phosphor layer is 17–21 mg cm −2147 Pm radioisotope. • The battery with ZnS:Cu phosphor layer can provide higher energy conversion efficiency. • The mechanism affecting the nuclear battery output performance is revealed. - Abstract: A radioluminescent nuclear battery based on the beta radioluminescence of phosphors is presented, and which consists of 147 Pm radioisotope, phosphor layers, and GaAs photovoltaic cell. ZnS:Cu and Y 2 O 2 S:Eu phosphor layers for various thickness were fabricated. To investigate the effect of phosphor layer parameters on the battery, the electrical properties were measured. Results indicate that the optimal thickness ranges for the ZnS:Cu and Y 2 O 2 S:Eu phosphor layers are 12 mg cm −2 to 14 mg cm −2 and 17 mg cm −2 to 21 mg cm −2 , respectively. ZnS:Cu phosphor layer exhibits higher fluorescence efficiency compared with the Y 2 O 2 S:Eu phosphor layer. Its spectrum properly matches the spectral response of GaAs photovoltaic cell. As a result, the battery with ZnS:Cu phosphor layer indicates higher energy conversion efficiency than that with Y 2 O 2 S:Eu phosphor layer. Additionally, the mechanism of the phosphor layer parameters that influence the output performance of the battery is discussed through the Monte Carlo method and transmissivity test

Estimating environmental co-benefits of U.S. low-carbon pathways using an integrated assessment model with state-level resolution.

Science.gov (United States)

Ou, Yang; Shi, Wenjing; Smith, Steven J; Ledna, Catherine M; West, J Jason; Nolte, Christopher G; Loughlin, Daniel H

2018-04-15

There are many technological pathways that can lead to reduced carbon dioxide emissions. However, these pathways can have substantially different impacts on other environmental endpoints, such as air quality and energy-related water demand. This study uses an integrated assessment model with state-level resolution of the energy system to compare environmental impacts of alternative low-carbon pathways for the United States. One set of pathways emphasizes nuclear energy and carbon capture and storage, while another set emphasizes renewable energy, including wind, solar, geothermal power, and bioenergy. These are compared with pathways in which all technologies are available. Air pollutant emissions, mortality costs attributable to particulate matter smaller than 2.5 μm in diameter, and energy-related water demands are evaluated for 50% and 80% carbon dioxide reduction targets in 2050. The renewable low-carbon pathways require less water withdrawal and consumption than the nuclear and carbon capture pathways. However, the renewable low-carbon pathways modeled in this study produce higher particulate matter-related mortality costs due to greater use of biomass in residential heating. Environmental co-benefits differ among states because of factors such as existing technology stock, resource availability, and environmental and energy policies.

On the corrosion behaviour of phosphoric irons in simulated concrete pore solution

International Nuclear Information System (INIS)

Sahoo, Gadadhar; Balasubramaniam, R.

2008-01-01

The corrosion behaviour of three phosphoric irons P 1 (Fe-0.11P-0.028C), P 2 (Fe-0.32P-0.026C) and P 3 (Fe-0.49P-0.022C) has been studied in simulated concrete pore solution (saturated Ca(OH) 2 solution) containing different chloride concentration. This has been compared with that of two commercial concrete reinforcement steels, a low carbon steel TN (Fe-0.148C-0.542Mn-0.128Si) and a microalloyed corrosion resistant steel CS (Fe-0.151C-0.088P-0.197Si-0.149Cr-0.417Cu). The beneficial aspect of phosphoric irons was revealed from potentiodynamic polarization experiments. The pitting potentials and pitting nucleation resistances for phosphoric irons and CS were higher than that for TN. Electrochemical impedance spectroscopy (EIS) studies revealed thickening and growth of passive film as a function of time in case of phosphoric irons and CS in saturated Ca(OH) 2 pore solutions without chloride and in the same solution with 0.05% Cl - and 0.1% Cl - . In case of TN, breakdown of passive film resulted in active corrosion in simulated pore solution containing 0.1% Cl - . Linear polarization resistance measurements complemented EIS results. Visual observations indicated that phosphoric iron P 3 was immune to corrosion even after 125 days of immersion in saturated Ca(OH) 2 solution containing 5% NaCl. The good corrosion resistance of phosphoric irons in simulated concrete pore solution containing chloride ions has been related to the formation of phosphate, based on ultraviolet spectrophotometric analysis and Pourbaix diagram of phosphorus-water system

Concentration and wavelength dependent frequency downshifting photoluminescence from a Tb3+ doped yttria nano-phosphor: A photochromic phosphor

Science.gov (United States)

Yadav, Ram Sagar; Rai, Shyam Bahadur

2018-03-01

In this article, the Tb3+ doped Y2O3 nano-phosphor has been synthesized through solution combustion method. The structural measurements of the nano-phosphor have been carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques, which reveal nano-crystalline nature. The Fourier transform infrared (FTIR) measurements reveal the presence of different molecular species in the nano-phosphor. The UV-Vis-NIR absorption spectrum of the nano-phosphor shows large number of bands due to charge transfer band (CTB) and 4f-4f electronic transitions of Tb3+ ion. The Tb3+ doped Y2O3 nano-phosphor emits intense green downshifting photoluminescence centered at 543 nm due to 5D4 → 7F5 transition on excitation with 350 nm. The emission intensity of the nano-phosphor is optimized at 1.0 mol% concentration of Tb3+ ion. When the as-synthesized nano-phosphor is annealed at higher temperature the emission intensity of the nano-phosphor enhances upto 5 times. The enhancement in the emission intensity is due to an increase in crystallinity of the nano-phosphor, reduction in surface defects and optical quenching centers. The CIE diagram reveals that the Tb3+ doped nano-phosphor samples show the photochromic nature (color tunability) with a change in the concentration of Tb3+ ion and excitation wavelength. The lifetime measurement indicates an increase in the lifetime for the annealed sample. Thus, the Tb3+ doped Y2O3 nano-phosphor may be used in photochromic displays and photonic devices.

MULTI-PHOTON PHOSPHOR FEASIBILITY RESEARCH

Energy Technology Data Exchange (ETDEWEB)

R. Graham; W. Chow

2003-05-01

Development of multi-photon phosphor materials for discharge lamps represents a goal that would achieve up to a doubling of discharge (fluorescent) lamp efficacy. This report reviews the existing literature on multi-photon phosphors, identifies obstacles in developing such phosphors, and recommends directions for future research to address these obstacles. To critically examine issues involved in developing a multi-photon phosphor, the project brought together a team of experts from universities, national laboratories, and an industrial lamp manufacturer. Results and findings are organized into three categories: (1) Multi-Photon Systems and Processes, (2) Chemistry and Materials Issues, and (3) Concepts and Models. Multi-Photon Systems and Processes: This category focuses on how to use our current understanding of multi-photon phosphor systems to design new phosphor systems for application in fluorescent lamps. The quickest way to develop multi-photon lamp phosphors lies in finding sensitizer ions for Gd{sup 3+} and identifying activator ions to red shift the blue emission from Pr{sup 3+} due to the {sup 1}S{sub 0} {yields} {sup 1}I{sub 6} transition associated with the first cascading step. Success in either of these developments would lead to more efficient fluorescent lamps. Chemistry and Materials Issues: The most promising multi-photon phosphors are found in fluoride hosts. However, stability of fluorides in environments typically found in fluorescent lamps needs to be greatly improved. Experimental investigation of fluorides in actual lamp environments needs to be undertaken while working on oxide and oxyfluoride alternative systems for backup. Concepts and Models: Successful design of a multi-photon phosphor system based on cascading transitions of Gd{sup 3+} and Pr{sup 3+} depends critically on how the former can be sensitized and the latter can sensitize an activator ion. Methods to predict energy level diagrams and Judd-Ofelt parameters of multi

Phosphor blends for high-CRI fluorescent lamps

Science.gov (United States)

Setlur, Anant Achyut [Niskayuna, NY; Srivastava, Alok Mani [Niskayuna, NY; Comanzo, Holly Ann [Niskayuna, NY; Manivannan, Venkatesan [Clifton Park, NY; Beers, William Winder [Chesterland, OH; Toth, Katalin [Pomaz, HU; Balazs, Laszlo D [Budapest, HU

2008-06-24

A phosphor blend comprises at least two phosphors each selected from one of the groups of phosphors that absorb UV electromagnetic radiation and emit in a region of visible light. The phosphor blend can be applied to a discharge gas radiation source to produce light sources having high color rendering index. A phosphor blend is advantageously includes the phosphor (Tb,Y,LuLa,Gd).sub.x(Al,Ga).sub.yO.sub.12:Ce.sup.3+, wherein x is in the range from about 2.8 to and including 3 and y is in the range from about 4 to and including 5.

Recovering uranium from phosphoric acid

International Nuclear Information System (INIS)

Anon.

1979-01-01

Wet-process phosphoric acid contains a significant amount of uranium. This uranium totals more than 1,500 tons/yr in current U.S. acid output--and projections put the uranium level at 8,000 tons/yr in the year 2000. Since the phosphoric acid is a major raw material for fertilizers, uranium finds its way into those products and is effectively lost as a resource, while adding to the amount of radioactive material that can contaminate the food chain. So, resource-conservation and environmental considerations both make recovery of the uranium from phosphoric acid desirable. This paper describes the newly developed process for recovering uranium from phosphoric acid by using solvent-extraction technique. After many extractants had been tested, the researchers eventually selected the combination of di (2-ethylhexyl) phosphoric acid (DEPA) and trioctylphosphine oxide (TOPO) as the most suitable. The flowscheme of the process is included

Ammonia lyases and aminomutases as biocatalysts for the synthesis of α-amino and β-amino acids.

Science.gov (United States)

Turner, Nicholas J

2011-04-01

Ammonia lyases catalyse the reversible addition of ammonia to cinnamic acid (1: R=H) and p-hydroxycinnamic (1: R=OH) to generate L-phenylalanine (2: R=H) and L-tyrosine (2: R=OH) respectively (Figure 1a). Both phenylalanine ammonia lyase (PAL) and tyrosine ammonia lyase (TAL) are widely distributed in plants, fungi and prokaryotes. Recently there has been interest in the use of these enzymes for the synthesis of a broader range of L-arylalanines. Aminomutases catalyse a related reaction, namely the interconversion of α-amino acids to β-amino acids (Figure 1b). In the case of L-phenylalanine, this reaction is catalysed by phenylalanine aminomutase (PAM) and proceeds stereospecifically via the intermediate cinnamic acid to generate β-Phe 3. Ammonia lyases and aminomutases are related in sequence and structure and share the same active site cofactor 4-methylideneimidazole-5-one (MIO). There is currently interest in the possibility of using these biocatalysts to prepare a wide range of enantiomerically pure l-configured α-amino and β-amino acids. Recent reviews have focused on the mechanism of these MIO containing enzymes. The aim of this review is to review recent progress in the application of ammonia lyase and aminomutase enzymes to prepare enantiomerically pure α-amino and β-amino acids. Copyright © 2010 Elsevier Ltd. All rights reserved.

Turning sunlight into stone: the oxalate-carbonate pathway in a tropical tree ecosystem

Directory of Open Access Journals (Sweden)

G. Cailleau

2011-07-01

Full Text Available An African oxalogenic tree, the iroko tree (Milicia excelsa, has the property to enhance carbonate precipitation in tropical oxisols, where such accumulations are not expected due to the acidic conditions in these types of soils. This uncommon process is linked to the oxalate-carbonate pathway, which increases soil pH through oxalate oxidation. In order to investigate the oxalate-carbonate pathway in the iroko system, fluxes of matter have been identified, described, and evaluated from field to microscopic scales. In the first centimeters of the soil profile, decaying of the organic matter allows the release of whewellite crystals, mainly due to the action of termites and saprophytic fungi. In addition, a concomitant flux of carbonate formed in wood tissues contributes to the carbonate flux and is identified as a direct consequence of wood feeding by termites. Nevertheless, calcite biomineralization of the tree is not a consequence of in situ oxalate consumption, but rather related to the oxalate oxidation inside the upper part of the soil. The consequence of this oxidation is the presence of carbonate ions in the soil solution pumped through the roots, leading to preferential mineralization of the roots and the trunk base. An ideal scenario for the iroko biomineralization and soil carbonate accumulation starts with oxalatization: as the iroko tree grows, the organic matter flux to the soil constitutes the litter, and an oxalate pool is formed on the forest ground. Then, wood rotting agents (mainly termites, saprophytic fungi, and bacteria release significant amounts of oxalate crystals from decaying plant tissues. In addition, some of these agents are themselves producers of oxalate (e.g. fungi. Both processes contribute to a soil pool of "available" oxalate crystals. Oxalate consumption by oxalotrophic bacteria can then start. Carbonate and calcium ions present in the soil solution represent the end products of the oxalate-carbonate

Kinetic and thermodynamic properties of alginate lyase and cellulase co-produced by Exiguobacterium species Alg-S5.

Science.gov (United States)

Mohapatra, Bidyut R

2017-05-01

In an effort to screen out the alginolytic and cellulolytic bacteria from the putrefying invasive seaweed Sargassum species accumulated off Barbados' coast, a potent bacterial strain was isolated. This bacterium, which simultaneously produced alginate lyase and cellulase, was identified as Exiguobacterium sp. Alg-S5 via the phylogenetic approach targeting the 16S rRNA gene. The co-produced alginate lyase and cellulase exhibited maximal enzymatic activity at pH 7.5 and at 40°C and 45°C, respectively. The K m and V max values recorded as 0.91mg/mL and 21.8U/mg-protein, respectively, for alginate lyase, and 10.9mg/mL and 74.6U/mg-protein, respectively, for cellulase. First order kinetic analysis of the thermal denaturation of the co-produced alginate lyase and cellulase in the temperature range from 40°C to 55°C revealed that both the enzymes were thermodynamically efficient by displaying higher activation energy and enthalpy of denaturation. These enzymatic properties indicate the potential industrial importance of this bacterium in algal biomass conversion. This appears to be the first report on assessing the efficacy of a bacterium for the co-production of alginate lyase and cellulase. Copyright © 2017 Elsevier B.V. All rights reserved.

46 CFR 151.50-23 - Phosphoric acid.

Science.gov (United States)

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Phosphoric acid. 151.50-23 Section 151.50-23 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-23 Phosphoric acid. (a) The term phosphoric acid as used in this subpart shall include, in addition to phosphoric acid, aqueous solutions of...

A QM/MM study of the reaction mechanism of (R)-hydroxynitrile lyases from Arabidopsis thaliana (AtHNL).

Science.gov (United States)

Zhu, Wenyou; Liu, Yongjun; Zhang, Rui

2015-01-01

Hydroxynitrile lyases (HNLs) catalyze the conversion of chiral cyanohydrins to hydrocyanic acid (HCN) and aldehyde or ketone. Hydroxynitrile lyase from Arabidopsis thaliana (AtHNL) is the first R-selective HNL enzyme containing an α/β-hydrolases fold. In this article, the catalytic mechanism of AtHNL was theoretically studied by using QM/MM approach based on the recently obtained crystal structure in 2012. Two computational models were constructed, and two possible reaction pathways were considered. In Path A, the calculation results indicate that the proton transfer from the hydroxyl group of cyanohydrin occurs firstly, and then the cleavage of C1-C2 bond and the rotation of the generated cyanide ion (CN(-)) follow, afterwards, CN(-) abstracts a proton from His236 via Ser81. The C1-C2 bond cleavage and the protonation of CN(-) correspond to comparable free energy barriers (12.1 vs. 12.2 kcal mol(-1)), suggesting that both of the two processes contribute a lot to rate-limiting. In Path B, the deprotonation of the hydroxyl group of cyanohydrin and the cleavage of C1-C2 bond take place in a concerted manner, which corresponds to the highest free energy barrier of 13.2 kcal mol(-1). The free energy barriers of Path A and B are very similar and basically agree well with the experimental value of HbHNL, a similar enzyme of AtHNL. Therefore, both of the two pathways are possible. In the reaction, the catalytic triad (His236, Ser81, and Asp208) acts as the general acid/base, and the generated CN(-) is stabilized by the hydroxyl group of Ser81 and the main-chain NH-groups of Ala13 and Phe82. © 2014 Wiley Periodicals, Inc.

Tuning the diurnal natural daylight with phosphor converted white LED – Advent of new phosphor blend composition

International Nuclear Information System (INIS)

Kim, Yoon Hwa; Arunkumar, Paulraj; Park, Seung Hyok; Yoon, Ho Shin; Im, Won Bin

2015-01-01

Highlights: • Designed phosphor blend that mimics diurnal daylight for health benefits. • Developed new phosphor blend composition that mimics natural sunlight under near UV. • The phosphor blend also exhibits high CRI (≥90) under blue LED excitation. • Fabricated WLED exhibited ∼91% spectral resemblance with daylight at 4500 K. • While ∼39.2% spectral resemblance were observed for YAG:Ce 3+ at 4500 K. - Abstract: We demonstrate the feasibility of developing phosphor converted white LED (pc-WLED) that mimics diurnal natural daylight with the newly designed phosphor blend in the color temperature (CCT) 2700–6000 K for health benefits. Natural daylight (sunlight) spectrum possesses broad emission in the visible region and closely approximates black body radiator, with color rendition index (CRI) of 100 under wide CCT (2500–6500 K). Current white light LEDs although are efficient and durable, they are not broad enough compared to daylight. We report new phosphor blend based on Sr 3 MgSi 2 O 8 :Eu 2+ blue phosphor with broad emission and high CRI ≥ 96 under both near UV and blue excitation. The fabricated WLED has exhibited ∼91% spectral resemblance with natural daylight compared to 39.2% for YAG:Ce 3+ white LED at 4500 K. The developed phosphor blend tunes the spectrum in wider CCT and would be a prospective candidate for full spectrum daylight WLED

A Catalase-related Hemoprotein in Coral Is Specialized for Synthesis of Short-chain Aldehydes: DISCOVERY OF P450-TYPE HYDROPEROXIDE LYASE ACTIVITY IN A CATALASE.

Science.gov (United States)

Teder, Tarvi; Lõhelaid, Helike; Boeglin, William E; Calcutt, Wade M; Brash, Alan R; Samel, Nigulas

2015-08-07

In corals a catalase-lipoxygenase fusion protein transforms arachidonic acid to the allene oxide 8R,9-epoxy-5,9,11,14-eicosatetraenoic acid from which arise cyclopentenones such as the prostanoid-related clavulones. Recently we cloned two catalase-lipoxygenase fusion protein genes (a and b) from the coral Capnella imbricata, form a being an allene oxide synthase and form b giving uncharacterized polar products (Lõhelaid, H., Teder, T., Tõldsepp, K., Ekins, M., and Samel, N. (2014) PloS ONE 9, e89215). Here, using HPLC-UV, LC-MS, and NMR methods, we identify a novel activity of fusion protein b, establishing its role in cleaving the lipoxygenase product 8R-hydroperoxy-eicosatetraenoic acid into the short-chain aldehydes (5Z)-8-oxo-octenoic acid and (3Z,6Z)-dodecadienal; these primary products readily isomerize in an aqueous medium to the corresponding 6E- and 2E,6Z derivatives. This type of enzymatic cleavage, splitting the carbon chain within the conjugated diene of the hydroperoxide substrate, is known only in plant cytochrome P450 hydroperoxide lyases. In mechanistic studies using (18)O-labeled substrate and incubations in H2(18)O, we established synthesis of the C8-oxo acid and C12 aldehyde with the retention of the hydroperoxy oxygens, consistent with synthesis of a short-lived hemiacetal intermediate that breaks down spontaneously into the two aldehydes. Taken together with our initial studies indicating differing gene regulation of the allene oxide synthase and the newly identified catalase-related hydroperoxide lyase and given the role of aldehydes in plant defense, this work uncovers a potential pathway in coral stress signaling and a novel enzymatic activity in the animal kingdom. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Pathways for implementing REDD+. Experiences from carbon markets and communities

Energy Technology Data Exchange (ETDEWEB)

Zhu, X; Ravnkilde Moeller, L; Lopez, T De; Romero, M Z

2011-07-01

This issue of Carbon Market Perspectives on 'Pathways for implementing REDD+: Experience from carbon markets and communities' discusses the role of carbon markets in scaling up investments for REDD+ in developing countries. Nine articles authored by experienced negotiators on REDD+, carbon market actors, project developers and other leading experts share experiences and make suggestions on the key elements of a future international REDD+ regime: Architecture and underlying principles, measuring, reporting and verification (MRV), private-sector involvement, the rights of indigenous people and local communities, biodiversity conservation and environmental integrity. The articles are grouped under three main topics: the lessons of existing REDD+ projects; the future REDD+ regime and the role of carbon markets; and experiences and ideas about the involvement of indigenous people and local communities. (LN)

Crystal structure and characterization of a novel L-serine ammonia-lyase from Rhizomucor miehei

Energy Technology Data Exchange (ETDEWEB)

Qin, Zhen [College of Food Science and Nutritional Engineering, Beijing Advanced Innovation Center of Food Nutrition and Human Health, China Agricultural University, Beijing 100083 (China); Yan, Qiaojuan [College of Engineering, China Agricultural University, Beijing 100083 (China); Ma, Qingjun [Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071 (China); Jiang, Zhengqiang, E-mail: zhqjiang@cau.edu.cn [College of Food Science and Nutritional Engineering, Beijing Advanced Innovation Center of Food Nutrition and Human Health, China Agricultural University, Beijing 100083 (China)

2015-10-23

L-serine ammonia-lyase, as a member of the β-family of pyridoxal-5′-phosphate (PLP) dependent enzymes, catalyzes the conversion of L-serine (L-threonine) to pyruvate (α-ketobutyrate) and ammonia. The crystal structure of L-serine ammonia-lyase from Rhizomucor miehei (RmSDH) was solved at 1.76 Å resolution by X-ray diffraction method. The overall structure of RmSDH had the characteristic β-family PLP dependent enzyme fold. It consisted of two distinct domains, both of which show the typical open twisted α/β structure. A PLP cofactor was located in the crevice between the two domains, which was attached to Lys52 by a Schiff-base linkage. Unique residue substitutions (Gly78, Pro79, Ser146, Ser147 and Thr312) were discovered at the catalytic site of RmSDH by comparison of structures of RmSDH and other reported eukaryotic L-serine ammonia-lyases. Optimal pH and temperature of the purified RmSDH were 7.5 and 40 °C, respectively. It was stable in the pH range of 7.0–9.0 and at temperatures below 40 °C. This is the first crystal structure of a fungal L-serine ammonia-lyase. It will be useful to study the catalytic mechanism of β-elimination enzymes and will provide a basis for further enzyme engineering. - Highlights: • The crystal structure of a fungal L-serine ammonia-lyase (RmSDH) was solved. • Five unique residue substitutions are found at the catalytic site of RmSDH. • RmSDH was expressed in Pichia. pastoris and biochemically characterized. • RmSDH has potential application in splitting D/L-serine.

Application of strong phosphoric acid to radiochemistry

International Nuclear Information System (INIS)

Terada, Kikuo

1977-01-01

Not only inorganic and organic compounds but also natural substrances, such as accumulations in soil, are completely decomposed and distilled by heating with strong phosphoric acid for 30 to 50 minutes. As applications of strong phosphoric acid to radiochemistry, determination of uranium and boron by use of solubilization effect of this substance, titration of uranyl ion by use of sulfuric iron (II) contained in this substance, application to tracer experiment, and determination of radioactive ruthenium in environmental samples are reviewed. Strong phosphoric acid is also applied to activation analysis, for example, determination of N in pyrographite with iodate potassium-strong phosphoric acid method, separation of Os and Ru with sulfuric cerium (IV) - strong phosphoric acid method or potassium dechromate-strong phosphoric acid method, analysis of Se, As and Sb rocks and accumulations with ammonium bromide, sodium chloride and sodium bromide-strong phosphoric acid method. (Kanao, N.)

Cystathionine .gamma.-lyase: Clinical, metabolic, genetic, and structural studies

Czech Academy of Sciences Publication Activity Database

Kraus, J. P.; Hašek, Jindřich; Kožich, V.; Collard, R.; Venezia, S.; Janošíková, B.; Wang, J.; Stabler, S. P.; Allen, R. H.; Jakobs, C.; Finn, C. T.; Chien, Y. H.; Hwu, W. L.; Hegele, R. A.; Mudd, S. H.

2009-01-01

Roč. 97, č. 4 (2009), s. 250-259 ISSN 1096-7192 R&D Projects: GA ČR GA305/07/1073 Institutional research plan: CEZ:AV0Z40500505 Keywords : cystathionine gamma-lyase * cystathioninuria * hypercystathioninemia Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.897, year: 2009

21 CFR 182.1073 - Phosphoric acid.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Phosphoric acid. 182.1073 Section 182.1073 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN....1073 Phosphoric acid. (a) Product. Phosphoric acid. (b) Conditions of use. This substance is generally...

21 CFR 582.1073 - Phosphoric acid.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Phosphoric acid. 582.1073 Section 582.1073 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1073 Phosphoric acid. (a) Product. Phosphoric acid. (b) Conditions of use. This substance is...

Lipid Biomarkers and Molecular Carbon Isotopes for Elucidating Carbon Cycling Pathways in Hydrothermal Vents

Science.gov (United States)

Zhang, C. L.; Dai, J.; Campbell, B.; Cary, C.; Sun, M.

2003-12-01

Increasing molecular evidence suggests that hydrothermal vents in mid-ocean ridges harbor large populations of free-living bacteria, particularly the epsilon Proteobacteria. However, pathways for carbon metabolism by these bacteria are poorly known. We are addressing this question by analyzing the lipid biomarkers and their isotope signatures in environments where the epsilon Proteobacteria are likely predominant. Solid materials were collected from hydrothermal vents in the East Pacific Rise and at the Guaymas Basin in the Gulf of California. Fatty acids extracted from these samples are dominated by 16:0 (27-41%), 18:0 (16-48%), 18:1 (11-42%), 16:1 (7-12%), and 14:0 (5-28%). In addition, 15:0 and anteiso-15:0 are significantly present (2-3%) in samples from the Guaymas Basin. The isotopic compositions of these fatty acids range from -15.0\\permil to -33.1\\permil with the most positive values occurring only in monounsaturated fatty acids (16:1 and 18:1). We are currently unable to assign these biomarkers to any of the epsilon Proteobacteria because biomarkers are poorly known for these organisms isolated from the vents. However, no polyunsaturated fatty acids were detected in these samples, which are consistent with the absence of vent animals at the sampling sites. Signature biomarkers of 20:1 and cy21:0, which are characteristic of the thermophilic chemolithoautotrophs such as Aquificales, are also absent in these samples. These results imply that the deeply branched Aquificales species do not constitute the major microbial community in these vent environments. The large range of molecular isotopic compositions suggests that these lipids are synthesized from various carbon sources with different isotopic compositions or through different biosynthetic pathways, or both. We are currently measuring the isotopic compositions of the total organic carbon in the bulk samples and will determine the fractionations between lipid biomarkers and the total organic carbon

Tuning the diurnal natural daylight with phosphor converted white LED – Advent of new phosphor blend composition

Energy Technology Data Exchange (ETDEWEB)

Kim, Yoon Hwa [School of Materials Science and Engineering, Chonnam National University, 300, Yongbong-dong, Buk-gu, Gwangju 500-757 (Korea, Republic of); Research Institute, Force4 Corp., Daechon-dong, Buk-gu, Gwangju 500-470 (Korea, Republic of); Arunkumar, Paulraj [School of Materials Science and Engineering, Chonnam National University, 300, Yongbong-dong, Buk-gu, Gwangju 500-757 (Korea, Republic of); Park, Seung Hyok; Yoon, Ho Shin [Research Institute, Force4 Corp., Daechon-dong, Buk-gu, Gwangju 500-470 (Korea, Republic of); Im, Won Bin, E-mail: imwonbin@jnu.ac.kr [School of Materials Science and Engineering, Chonnam National University, 300, Yongbong-dong, Buk-gu, Gwangju 500-757 (Korea, Republic of)

2015-03-15

Highlights: • Designed phosphor blend that mimics diurnal daylight for health benefits. • Developed new phosphor blend composition that mimics natural sunlight under near UV. • The phosphor blend also exhibits high CRI (≥90) under blue LED excitation. • Fabricated WLED exhibited ∼91% spectral resemblance with daylight at 4500 K. • While ∼39.2% spectral resemblance were observed for YAG:Ce{sup 3+} at 4500 K. - Abstract: We demonstrate the feasibility of developing phosphor converted white LED (pc-WLED) that mimics diurnal natural daylight with the newly designed phosphor blend in the color temperature (CCT) 2700–6000 K for health benefits. Natural daylight (sunlight) spectrum possesses broad emission in the visible region and closely approximates black body radiator, with color rendition index (CRI) of 100 under wide CCT (2500–6500 K). Current white light LEDs although are efficient and durable, they are not broad enough compared to daylight. We report new phosphor blend based on Sr{sub 3}MgSi{sub 2}O{sub 8}:Eu{sup 2+} blue phosphor with broad emission and high CRI ≥ 96 under both near UV and blue excitation. The fabricated WLED has exhibited ∼91% spectral resemblance with natural daylight compared to 39.2% for YAG:Ce{sup 3+} white LED at 4500 K. The developed phosphor blend tunes the spectrum in wider CCT and would be a prospective candidate for full spectrum daylight WLED.

Color stable manganese-doped phosphors

Science.gov (United States)

Lyons, Robert Joseph [Burnt Hills, NY; Setlur, Anant Achyut [Niskayuna, NY; Deshpande, Anirudha Rajendra [Twinsburg, OH; Grigorov, Ljudmil Slavchev [Sofia, BG

2012-08-28

A process for preparing color stable Mn.sup.+4 doped phosphors includes providing a phosphor of formula I; A.sub.x[MF.sub.y]:Mn.sup.+4 I and contacting the phosphor in particulate form with a saturated solution of a composition of formula II in aqueous hydrofluoric acid; A.sub.x[MF.sub.y]; II wherein A is Li, Na, K, Rb, Cs, NR.sub.4 or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; R is H, lower alkyl, or a combination thereof; x is the absolute value of the charge of the [MF.sub.y] ion; and y is 5, 6 or 7. In particular embodiments, M is Si, Ge, Sn, Ti, Zr, or a combination thereof. A lighting apparatus capable of emitting white light includes a semiconductor light source; and a phosphor composition radiationally coupled to the light source, and which includes a color stable Mn.sup.+4 doped phosphor.

Processes for the production of hydroxycinnamic acids using polypeptides having tyrosine ammonia lyase activity

DEFF Research Database (Denmark)

2016-01-01

The present invention generally relates to the field of biotechnology as it applies to the production of hydroxycinnamic acids using polypeptides having tyrosine ammonia lyase activity. More particularly, the present invention pertains to polypeptides having tyrosine ammonia lyase activity and high...... substrate specificity towards tyrosine, which makes them particularly suitable in the production of p-coumaric acid and other hydroxycinnamic acids. The present invention thus provides processes for the production of p-coumaric acid and other hydroxycinnamic acids employing these polypeptides as well...

Improvements in x-ray image converters and phosphors

International Nuclear Information System (INIS)

Rabatin, J.G.

1981-01-01

Improvements to an X-ray image converter comprising crystals of rare earth phosphor admixtures are described. The phosphor admixtures utilize thulium-activated lanthanum and/or gadolinium oxyhalide phosphor material to increase the relative speed and resolution of an X-ray image compared with conventional rare earth phosphors. Examples of various radiographic screens containing one or more of the phosphor materials are given. (U.K.)

Fluorescent lighting with aluminum nitride phosphors

Science.gov (United States)

Cherepy, Nerine J.; Payne, Stephen A.; Seeley, Zachary M.; Srivastava, Alok M.

2016-05-10

A fluorescent lamp includes a glass envelope; at least two electrodes connected to the glass envelope; mercury vapor and an inert gas within the glass envelope; and a phosphor within the glass envelope, wherein the phosphor blend includes aluminum nitride. The phosphor may be a wurtzite (hexagonal) crystalline structure Al.sub.(1-x)M.sub.xN phosphor, where M may be drawn from beryllium, magnesium, calcium, strontium, barium, zinc, scandium, yttrium, lanthanum, cerium, praseodymium, europium, gadolinium, terbium, ytterbium, bismuth, manganese, silicon, germanium, tin, boron, or gallium is synthesized to include dopants to control its luminescence under ultraviolet excitation. The disclosed Al.sub.(1-x)M.sub.xN:Mn phosphor provides bright orange-red emission, comparable in efficiency and spectrum to that of the standard orange-red phosphor used in fluorescent lighting, Y.sub.2O.sub.3:Eu. Furthermore, it offers excellent lumen maintenance in a fluorescent lamp, and does not utilize "critical rare earths," minimizing sensitivity to fluctuating market prices for the rare earth elements.

Hematopoietic sphingosine 1-phosphate lyase deficiency decreases atherosclerotic lesion development in LDL-receptor deficient mice.

Directory of Open Access Journals (Sweden)

Martine Bot

Full Text Available AIMS: Altered sphingosine 1-phosphate (S1P homeostasis and signaling is implicated in various inflammatory diseases including atherosclerosis. As S1P levels are tightly controlled by S1P lyase, we investigated the impact of hematopoietic S1P lyase (Sgpl1(-/- deficiency on leukocyte subsets relevant to atherosclerosis. METHODS AND RESULTS: LDL receptor deficient mice that were transplanted with Sgpl1(-/- bone marrow showed disrupted S1P gradients translating into lymphopenia and abrogated lymphocyte mitogenic and cytokine response as compared to controls. Remarkably however, Sgpl1(-/- chimeras displayed mild monocytosis, due to impeded stromal retention and myelopoiesis, and plasma cytokine and macrophage expression patterns, that were largely compatible with classical macrophage activation. Collectively these two phenotypic features of Sgpl1 deficiency culminated in diminished atherogenic response. CONCLUSIONS: Here we not only firmly establish the critical role of hematopoietic S1P lyase in controlling S1P levels and T cell trafficking in blood and lymphoid tissue, but also identify leukocyte Sgpl1 as critical factor in monocyte macrophage differentiation and function. Its, partly counterbalancing, pro- and anti-inflammatory activity spectrum imply that intervention in S1P lyase function in inflammatory disorders such as atherosclerosis should be considered with caution.

Pathways for implementing REDD+. Experiences from carbon markets and communities

Energy Technology Data Exchange (ETDEWEB)

Zhu, X.; Ravnkilde Moeller, L.; Lopez, T. De; Romero, M.Z.

2011-07-01

This issue of Carbon Market Perspectives on 'Pathways for implementing REDD+: Experience from carbon markets and communities' discusses the role of carbon markets in scaling up investments for REDD+ in developing countries. Nine articles authored by experienced negotiators on REDD+, carbon market actors, project developers and other leading experts share experiences and make suggestions on the key elements of a future international REDD+ regime: Architecture and underlying principles, measuring, reporting and verification (MRV), private-sector involvement, the rights of indigenous people and local communities, biodiversity conservation and environmental integrity. The articles are grouped under three main topics: the lessons of existing REDD+ projects; the future REDD+ regime and the role of carbon markets; and experiences and ideas about the involvement of indigenous people and local communities. (LN)

Characterization of C-S lyase from Lactobacillus delbrueckii subsp. bulgaricus ATCC BAA-365 and its potential role in food flavour applications.

Science.gov (United States)

Allegrini, Alessandra; Astegno, Alessandra; La Verde, Valentina; Dominici, Paola

2017-04-01

Volatile thiols have substantial impact on the aroma of many beverages and foods. Thus, the control of their formation, which has been linked to C-S lyase enzymatic activities, is of great significance in industrial applications involving food flavours. Herein, we have carried out a spectroscopic and functional characterization of a putative pyridoxal 5'-phosphate (PLP)-dependent C-S lyase from the lactic acid bacterium Lactobacillus delbrueckii subsp. bulgaricus ATCC BAA-365 (LDB C-S lyase). Recombinant LDB C-S lyase exists as a tetramer in solution and shows spectral properties of enzymes containing PLP as cofactor. The enzyme has a broad substrate specificity toward sulphur-containing amino acids with aminoethyl-L-cysteine and L-cystine being the most effective substrates over L-cysteine and L-cystathionine. Notably, the protein also reveals cysteine-S-conjugate β-lyase activity in vitro, and is able to cleave a cysteinylated substrate precursor into the corresponding flavour-contributing thiol, with a catalytic efficiency higher than L-cystathionine. Contrary to similar enzymes of other lactic acid bacteria however, LDB C-S lyase is not capable of α,γ-elimination activity towards L-methionine to produce methanethiol, which is a significant compound in flavour development. Based on our results, future developments can be expected regarding the flavour-forming potential of Lactobacillus C-S lyase and its use in enhancing food flavours. © The Authors 2017. Published by Oxford University Press on behalf of the Japanese Biochemical Society. All rights reserved.

Uranium extraction from phosphoric acid

International Nuclear Information System (INIS)

Lounis, A.

1983-05-01

A study has been carried out for the extraction of uranium from phosphoric acid produced in Algeria. First of all, the Algerian phosphoric acid produced in Algeria by SONATRACH has been characterised. This study helped us to synthesize a phosphoric acid that enabled us to pass from laboratory tests to pilot scale tests. We have then examined extraction and stripping parameters: diluent, DZEPHA/TOPO ratio and oxidising agent. The laboratory experiments enabled us to set the optimum condition for the choice of diluent, extractant concentration, ratio of the synergic mixture, oxidant concentration, redox potential. The equilibrium isotherms lead to the determination of the number of theoretical stages for the uranium extraction and stripping of uranium, then the extraction from phosphoric acid has been verified on a pilot scale (using a mixer-settler)

Phosphors for X-ray intensification screens

International Nuclear Information System (INIS)

Rebatin, J.G.

1980-01-01

An improved rare earth oxyhalide phosphor for x-ray intensification screens is described. The phosphors, of formula LnOX.T where Ln = La or Gd, X = Cl or Br and T = Tm or Tb, are mixed with a small amount of a trivalent antimony compound. The addition of antimony overcomes ageing due to attack by atmospheric moisture and renders the phosphor freeflowing so that dispersions can be readily made. Preferably the phosphor is washed with an aqueous solution of the antimony compound and the compound is the fluoride, chloride or butoxide, or potassium antimony tartrate. (U.K.)

Nitric-phosphoric acid oxidation of solid and liquid organic materials

International Nuclear Information System (INIS)

Pierce, R.A.; Smith, J.R.; Poprik, D.C.

1995-01-01

Nitric-phosphoric acid oxidation has been developed specifically to address issues that face the Savannah River Site, other defense-related facilities, private industry, and small-volume generators such as university and medical laboratories. Initially tested to destroy and decontaminate SRS solid, Pu-contaminated job-control waste, the technology has also exhibited potential for remediating hazardous and mixed-hazardous waste forms. The process is unique to Savannah River and offers a valuable alternative to other oxidation processes that require extreme temperatures and/or elevated pressures. To address the broad categories of waste, many different organic compounds which represent a cross-section of the waste that must be treated have been successfully oxidized. Materials that have been quantitatively oxidized at atmospheric pressure below 180 degrees C include neoprene, cellulose, EDTA, tributylphosphate, and nitromethane. More stable compounds such as benzoic acid, polyethylene, oils, and resins have been completely decomposed below 200 degrees C and 10 psig. The process uses dilute nitric acid in a concentrated phosphoric acid media as the main oxidant for the organic compounds. Phosphoric acid allow nitric acid to be retained in solution well above its normal boiling point. The reaction forms NOx vapors which can be reoxidized and recycled using air and water. The addition of 0.001M Pd(II) reduces CO generation to near 1% of the released carbon gases. The advantages of this process are that it is straightforward, uses relatively inexpensive reagents, operates at relatively low temperature and pressure, and produces final solutions which are compatible with stainless steel equipment. For organic wastes, all carbon, hydrogen, and nitrogen are converted to gaseous products. If interfaced with an acid recovery system which converts NOx back to nitric acid, the net oxidizer would be oxygen from air

Novel Pectate Lyase Genes of Heterodera glycines Play Key Roles in the Early Stage of Parasitism.

Directory of Open Access Journals (Sweden)

Huan Peng

Full Text Available Pectate lyases are known to play a key role in pectin degradation by catalyzing the random cleavage of internal polymer linkages (endo-pectinases. In this paper, four novel cDNAs, designated Hg-pel-3, Hg-pel-4, Hg-pel-6 and Hg-pel-7, that encode pectate lyases were cloned and characterized from the soybean cyst nematode, Heterodera glycines. The predicted protein sequences of HG-PEL-3, HG-PEL-4 and HG-PEL-6 differed significantly in both their amino acid sequences and their genomic structures from other pectate lyases of H. glycines (HG-PEL-1, HG-PEL-2 and HG-PEL-7. A phylogenetic study revealed that the pectate lyase proteins of H. glycines are clustered into distinct clades and have distinct numbers and positioning of introns, which suggests that the pectate lyase genes of H. glycines may have evolved from at least two ancestral genes. A Southern blot analysis revealed that multiple Hg-pel-6-like genes were present in the H. glycines genome. In situ hybridization showed that four novel pectate lyases (Hg-pel-3, Hg-pel-4, Hg-pel-6 and Hg-pel-7 were actively transcribed in the subventral esophageal gland cells. A semi-quantitative RT-PCR assay supported the finding that the expression of these genes was strong in the egg, pre-parasitic second-stage juvenile (J2 and early parasitic J2 stages and that it declined in further developmental stages of the nematode. This expression pattern suggests that these proteins play a role in the migratory phase of the nematode life cycle. Knocking down Hg-pel-6 using in vitro RNA interference resulted in a 46.9% reduction of the number of nematodes that invaded the plants and a 61.5% suppression of the development of H. glycines females within roots compared to the GFP-dsRNA control. Plant host-derived RNAi induced the silencing of the Hg-pel-6gene, which significantly reduced the nematode infection levels at 7 Days post inoculation (dpi. Similarly, this procedure reduced the number of female adults at 40 dpi

Method of preparing a thermoluminescent phosphor

Science.gov (United States)

Lasky, Jerome B.; Moran, Paul R.

1979-01-01

A thermoluminescent phosphor comprising LiF doped with boron and magnesium is produced by diffusion of boron into a conventional LiF phosphor doped with magnesium. Where the boron dopant is made to penetrate only the outer layer of the phosphor, it can be used to detect shallowly penetrating radiation such as tritium beta ays in the presence of a background of more penetrating radiation.

The Influence of Phosphor and Binder Chemistry on the Aging Characteristics of Remote Phosphor Products

Energy Technology Data Exchange (ETDEWEB)

Davis, Lynn; Yaga, Robert; Lamvik, Michael; Mills, Karmann; Fletcher, B.

2017-06-30

The influence of phosphor and binder layer chemistries on the lumen maintenance and color stability of remote phosphor disks were examined using wet high-temperature operational lifetime testing (WHTOL). As part of the experimental matrix, two different correlated color temperature (CCT) values, 2700 K and 5000 K, were studied and each had a different binder chemistry. The 2700 K samples used a urethane binder whereas the 5000 K samples used an acrylate binder. Experimental conditions were chosen to enable study of the binder and phosphor chemistries and to minimize photo-oxidation of the polycarbonate substrate. Under the more severe WHTOL conditions of 85°C and 85% relative humidity (RH), absorption in the binder layer significantly reduced luminous flux and produced a blue color shift. The milder WHTOL conditions of 75°C and 75% RH, resulted in chemical changes in the binder layer that may alter its index of refraction. As a result, lumen maintenance remained high, but a slight yellow shift was found. The aging of remote phosphor products provides insights into the impact of materials on the performance of phosphors in an LED lighting system.

Functional group diversity is key to Southern Ocean benthic carbon pathways.

Directory of Open Access Journals (Sweden)

David K A Barnes

Full Text Available High latitude benthos are globally important in terms of accumulation and storage of ocean carbon, and the feedback this is likely to have on regional warming. Understanding this ecosystem service is important but difficult because of complex taxonomic diversity, history and geography of benthic biomass. Using South Georgia as a model location (where the history and geography of benthic biology is relatively well studied we investigated whether the composition of functional groups were critical to benthic accumulation, immobilization and burial pathway to sequestration-and also aid their study through simplification of identification. We reclassified [1], [2] morphotype and carbon mass data to 13 functional groups, for each sample of 32 sites around the South Georgia continental shelf. We investigated the influence on carbon accumulation, immobilization and sequestration estimate by multiple factors including the compositions of functional groups. Functional groups showed high diversity within and between sites, and within and between habitat types. Carbon storage was not linked to a functional group in particular but accumulation and immobilization increased with the number of functional groups present and the presence of hard substrata. Functional groups were also important to carbon burial rate, which increased with the presence of mixed (hard and soft substrata. Functional groups showed high surrogacy for taxonomic composition and were useful for examining contrasting habitat categorization. Functional groups not only aid marine carbon storage investigation by reducing time and the need for team size and speciality, but also important to benthic carbon pathways per se. There is a distinct geography to seabed carbon storage; seabed boulder-fields are hotspots of carbon accumulation and immobilization, whilst the interface between such boulder-fields and sediments are key places for burial and sequestration.

Priming ammonia lyases and aminomutases for industrial and therapeutic applications

NARCIS (Netherlands)

Heberling, Matthew M.; Wu, Bian; Bartsch, Sebastian; Janssen, Dick B.

Ammonia lyases (AL) and aminomutases (AM) are emerging in green synthetic routes to chiral amines and an AL is being explored as an enzyme therapeutic for treating phenylketonuria and cancer. Although the restricted substrate range of the wild-type enzymes limits their widespread application, the

Correlation between the cystathionine-r-lyase (CES) and the ...

African Journals Online (AJOL)

Background: The infection of Helicobacter pylori (H. pylori) is one of the most important causes of gastric ulcer disease. The role of hydrogen sulfide (H2S) production in H. pylori-induced gastric ulcer disease. Aim: The expression of cystathionine-γ-lyase (CSE) was determined, and correlated with the severity of gastric ulcer ...

Production of Odd-Carbon Dicarboxylic Acids in Escherichia coli Using an Engineered Biotin–Fatty Acid Biosynthetic Pathway

Energy Technology Data Exchange (ETDEWEB)

Haushalter, Robert W. [Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Physical Bioscience Division; Phelan, Ryan M. [Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Physical Bioscience Division; Hoh, Kristina M. [Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Physical Bioscience Division; Su, Cindy [Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Physical Bioscience Division; Wang, George [Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Physical Bioscience Division; Baidoo, Edward E. K. [Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Physical Bioscience Division; Keasling, Jay D. [Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Physical Bioscience Division

2017-03-14

Dicarboxylic acids are commodity chemicals used in the production of plastics, polyesters, nylons, fragrances, and medications. Bio-based routes to dicarboxylic acids are gaining attention due to environmental concerns about petroleum-based production of these compounds. Some industrial applications require dicarboxylic acids with specific carbon chain lengths, including odd-carbon species. Biosynthetic pathways involving cytochrome P450-catalyzed oxidation of fatty acids in yeast and bacteria have been reported, but these systems produce almost exclusively even-carbon species. Here in this paper we report a novel pathway to odd-carbon dicarboxylic acids directly from glucose in Escherichia coli by employing an engineered pathway combining enzymes from biotin and fatty acid synthesis. Optimization of the pathway will lead to industrial strains for the production of valuable odd-carbon diacids.

Estimating environmental co-benefits of U.S. low-carbon pathways using an integrated assessment model with state-level resolution

Energy Technology Data Exchange (ETDEWEB)

Ou, Yang; Shi, Wenjing; Smith, Steven J.; Ledna, Catherine M.; West, J. Jason; Nolte, Christopher G.; Loughlin, Daniel H.

2018-04-01

There are many technological pathways that can lead to reduced carbon dioxide (CO₂) emissions. However, these pathways can have substantially different impacts on other environmental endpoints, such as air quality and energy-related water demand. This study uses an integrated assessment model with state-level resolution of the U.S. energy system to compare environmental impacts of alternative low-carbon pathways. One set of pathways emphasizes nuclear energy and carbon capture and storage (NUC/CCS), while another set emphasizes renewable energy (RE). These are compared with pathways in which all technologies are available. Air pollutant emissions, mortality costs attributable to particulate matter less than 2.5 microns in diameter (PM2.5), and energy-related water demands are evaluated for 50% and 80% CO₂ reduction targets in the U.S. in 2050. The RE low-carbon pathways require less water withdrawal and consumption than the NUC/CCS pathways because of the large cooling demands of nuclear power and CCS. However, the NUC/CCS low-carbon pathways produce greater health benefits, mainly because the NUC/CCS assumptions result in less primary PM2.5 emissions from residential wood combustion. Environmental co-benefits differ among states because of factors such as existing technology stock, resource availability, and environmental and energy policies. An important finding is that biomass in the building sector can offset some of the health co-benefits of the low-carbon pathways even though it plays only a minor role in reducing CO₂ emissions.

Consumption of Pt anode in phosphoric acid

Energy Technology Data Exchange (ETDEWEB)

Kamiya, N.; Urata, K.; Motohira, N.; Ota, K. [Yokohama National University, Yokohama (Japan)

1997-12-05

Consumption of Pt anode was investigated in phosphoric acid of various concentration. In 30-70wt% phosphoric acid, Pt dissolved at the rate of 19{mu}gcm{sup -2}h{sup -1}. On the other hand, in 85 wt% phosphoric acid, the amount increased to 0.91 mgcm{sup -2}h{sup -1} which is ca. 180 and 1800 times as much as in 1M sulfuric acid and 1M alkaline solution, respectively. In the diluted phosphoric acid solution, the Pt surface was covered with Pt oxides during the electrolysis, which would prevent the surface from corrosion. However, in the concentrated phosphoric acid, no such oxide surface was observed. Concentrated phosphoric acid might form stable complex with Pt species, therefore the uncovered bare Pt surface is situated in the serious corrosion condition under the high overvoltage and Pt would dissolve into the solution directly instead of forming the Pt oxides. 11 refs., 9 figs., 1 tab.

Process for recovering a uranium containing concentrate and purified phosphoric acid from a wet process phosphoric acid containing uranium

International Nuclear Information System (INIS)

Weterings, C.A.M.; Janssen, J.A.

1985-01-01

A process is claimed for recovering from a wet process phosphoric acid which contains uranium, a uranium containing concentrate and a purified phosphoric acid. The wet process phosphoric acid is treated with a precipitant in the presence of a reducing agent and an aliphatic ketone

Process for recovering a uranium containing concentrate and purified phosphoric acid from a wet process phosphoric acid containing uranium

Energy Technology Data Exchange (ETDEWEB)

Weterings, C.A.M.; Janssen, J.A.

1985-04-30

A process is claimed for recovering from a wet process phosphoric acid which contains uranium, a uranium containing concentrate and a purified phosphoric acid. The wet process phosphoric acid is treated with a precipitant in the presence of a reducing agent and an aliphatic ketone.

Method of purifying phosphoric acid after solvent extraction

International Nuclear Information System (INIS)

Kouloheris, A.P.; Lefever, J.A.

1979-01-01

A method of purifying phosphoric acid after solvent extraction is described. The phosphoric acid is contacted with a sorbent which sorbs or takes up the residual amount of organic carrier and the phosphoric acid separated from the organic carrier-laden sorbent. The method is especially suitable for removing residual organic carrier from phosphoric acid after solvent extraction uranium recovery. (author)

Photoluminescent properties of Sr2CeO4: Eu3+ and Sr2CeO4: Eu2+ phosphors suitable for near ultraviolet excitation

International Nuclear Information System (INIS)

Suresh, K.; Poornachandra Rao, N.V.; Murthy, K.V.R.

2014-01-01

Powder phosphors of 1 mol% Eu 3+ - and Eu 2+ -doped strontium cerium oxide (Sr 2 CeO 4 ) were synthesized by standard solid-state reaction method. Eu 3+ - and Eu 2+ -doped Sr 2 CeO 4 phosphors fired at 1100 ℃ for 2 h were analysed by X-ray diffraction (XRD) and photoluminescence (PL) techniques. The XRD patterns confirm that the obtained phosphors are a single phase of Sr 2 CeO 4 composed of orthorhombic structure. Room temperature PL excitation spectrum of air-heated Sr 2 CeO 4 : Eu phosphor has exhibited bands at 260, 280 and 350 nm. Whereas the excitation spectrum of Sr 2 CeO 4 : Eu phosphor heated under reducing (carbon) atmosphere exhibited single broadband range from 260 to 390 nm. The (PL) emission peaks of both the phosphors at 467 (blue), 537 (green) and 616 nm (red) generate white light under 260, 280 and 350 nm excitation wavelengths. The Commission International de l'Eclairage (CIE) colour coordinates conforms that these phosphors emitting white light. The results reveal that these phosphors are multifunctional phosphors which emit white light under these excitations that they could be used as white components for display and lamp devices and as well as possible good light-conversion phosphor LEDs under near-ultraviolet (nUV) chip. (author)

Characterization of the N-linked glycosylation site of recombinant pectate lyase

NARCIS (Netherlands)

Colangelo, J.; Licon, V.; Benen, J.A.E.; Visser, J.; Bergmann, C.; Orlando, R.

1999-01-01

Recombinant pectate lyase from Aspergillus niger was overexpressed in Aspergillus nidulans. The two recombinant proteins produced differed in molecular mass by 1200 Da, which suggested that the larger molecular weight protein was glycosylated. The deduced amino acid sequence was searched for

Nitric-phosphoric acid oxidation of organic waste materials

International Nuclear Information System (INIS)

Pierce, R.A.; Smith, J.R.

1995-01-01

A wet chemical oxidation technology has been developed to address issues facing defense-related facilities, private industry, and small-volume generators such as university and medical laboratories. Initially tested to destroy and decontaminate a heterogenous mixture of radioactive-contaminated solid waste, the technology can also remediate other hazardous waste forms. The process, unique to Savannah River, offers a valuable alternative to incineration and other high-temperature or high-pressure oxidation processes. The process uses nitric acid in phosphoric acid; phosphoric acid allows nitric acid to be retained in solution well above its normal boiling point. The reaction converts organics to carbon dioxide and water, and generates NO x vapors which can be recycled using air and water. Oxidation is complete in one to three hours. In previous studies, many organic compounds were completely oxidized, within experimental error, at atmospheric pressure below 180 degrees C; more stable compounds were decomposed at 200 degrees C and 170 kPa. Recent studies have evaluated processing parameters and potential throughputs for three primary compounds: EDTA, polyethylene, and cellulose. The study of polyvinylchloride oxidation is incomplete at this time

Biochemical, Kinetic, and Spectroscopic Characterization of Ruegeria pomeroyi DddW--A Mononuclear Iron-Dependent DMSP Lyase.

Directory of Open Access Journals (Sweden)

Adam E Brummett

Full Text Available The osmolyte dimethylsulfoniopropionate (DMSP is a key nutrient in marine environments and its catabolism by bacteria through enzymes known as DMSP lyases generates dimethylsulfide (DMS, a gas of importance in climate regulation, the sulfur cycle, and signaling to higher organisms. Despite the environmental significance of DMSP lyases, little is known about how they function at the mechanistic level. In this study we biochemically characterize DddW, a DMSP lyase from the model roseobacter Ruegeria pomeroyi DSS-3. DddW is a 16.9 kDa enzyme that contains a C-terminal cupin domain and liberates acrylate, a proton, and DMS from the DMSP substrate. Our studies show that as-purified DddW is a metalloenzyme, like the DddQ and DddP DMSP lyases, but contains an iron cofactor. The metal cofactor is essential for DddW DMSP lyase activity since addition of the metal chelator EDTA abolishes its enzymatic activity, as do substitution mutations of key metal-binding residues in the cupin motif (His81, His83, Glu87, and His121. Measurements of metal binding affinity and catalytic activity indicate that Fe(II is most likely the preferred catalytic metal ion with a nanomolar binding affinity. Stoichiometry studies suggest DddW requires one Fe(II per monomer. Electronic absorption and electron paramagnetic resonance (EPR studies show an interaction between NO and Fe(II-DddW, with NO binding to the EPR silent Fe(II site giving rise to an EPR active species (g = 4.29, 3.95, 2.00. The change in the rhombicity of the EPR signal is observed in the presence of DMSP, indicating that substrate binds to the iron site without displacing bound NO. This work provides insight into the mechanism of DMSP cleavage catalyzed by DddW.

The influence of carbon source and calcium on the production of ...

African Journals Online (AJOL)

use

2011-12-10

Dec 10, 2011 ... The influence of carbon source and calcium on the production of ... Furthermore, since the middle lamella contains high levels of calcium, it was thought that it may play an important ..... Processing of the pectate lyase PelI by ...

White light-emitting diodes (LEDs) using (oxy)nitride phosphors

International Nuclear Information System (INIS)

Xie, R-J; Hirosaki, N; Sakuma, K; Kimura, N

2008-01-01

(Oxy)nitride phosphors have attracted great attention recently because they are promising luminescent materials for phosphor-converted white light-emitting diodes (LEDs). This paper reports the luminescent properties of (oxy)nitride phosphors in the system of M-Si-Al-O-N (M = Li, Ca or Sr), and optical properties of white LEDs using a GaN-based blue LED and (oxy)nitride phosphors. The phosphors show high conversion efficiency of blue light, suitable emission colours and small thermal quenching. The bichromatic white LEDs exhibit high luminous efficacy (∼55 lm W -1 ) and the multi-phosphor converted white LEDs show high colour rendering index (Ra 82-95). The results indicate that (oxy)nitride phosphors demonstrate their superior suitability to use as down-conversion luminescent materials in white LEDs

[Change traits of phosphorous consumption structure in China and their effects on environmental phosphorous loads].

Science.gov (United States)

Ma, Dun-Chao; Hu, Shan-Ying; Chen, Ding-Jiang; Li, You-Run

2012-04-01

Substance flow analysis was used to construct a model to analyze change traits of China's phosphorous (P) consumption structure from 1980 to 2008 and their influences on environmental phosphorous loads, then the correlation between several socioeconomic factors and phosphorous consumption pollution was investigated. It is found that phosphorous nutrient inputs of urban life and rural life on a per capita level climbed to 1.20 kg x a(-1) and 0.99 kg x a(-1) from 0.83 kg x a(-1) and 0.75 kg x a(-1) respectively, but phosphorous recycling ratios of urban life fell to 15.6% from 62.6%. P inputs of animal husbandry and planting also kept increasing, but the recycling ratio of the former decreased from 67.5% to 40.5%, meanwhile much P input of the latter was left in agricultural soil. Correlation coefficients were all above 0.90, indicating that population, urbanization level, development levels of planting and animal husbandry were important incentives for P consumption pollution in China. Environmental Kuznets curve showed that China still stayed in the early development stage, promoting economic growth at an expense of environmental quality. This study demonstrates that China's P consumption system is being transformed into a linear and open structure, and that P nutrient loss and environmental P loads increase continually.

Re-processing CRT phosphors for mercury-free applications

International Nuclear Information System (INIS)

Dexpert-Ghys, Jeannette; Regnier, Sophie; Canac, Sophie; Beaudette, Tristan; Guillot, Philippe; Caillier, Bruno; Mauricot, Robert; Navarro, Julien; Sekhri, Salem

2009-01-01

This study is part of an operation in the framework of treatment and revalorization of IEEE (Informatics, Electronics and related) wastes. It aims to recover the active phosphors in cathode ray tubes (CRTs) and to re-cycle these powders by appropriate treatments as phosphors for mercury-free applications such as plasma display panels, flat lamps, advertising and lighting. The studied waste comes from a large panel of CRTs from any supplier. Several thermo-chemical treatments have been investigated. The removal of zinc sulfide-based phosphors and the recovery of a red phosphor Y 2 O 3 :Eu 3+ has been achieved by one (basic attack) route. The photoluminescence efficiency under VUV excitation of the obtained powders is at most 30% that of a commercial phosphor. The second route (acid attack) appears less promising. It has been established that silicate-based impurities could prevent isolating the yttrium based phosphor.

Re-processing CRT phosphors for mercury-free applications

Energy Technology Data Exchange (ETDEWEB)

Dexpert-Ghys, Jeannette, E-mail: jdexpert@cemes.f [CEMES, 29 rue Jeanne Marvig, BP 94347, 31055 Toulouse cedex 4 (France); Regnier, Sophie; Canac, Sophie [ICAM, 75 avenue de Grande Bretagne, 31300 Toulouse (France); Beaudette, Tristan; Guillot, Philippe; Caillier, Bruno [DPHE, Universite Jean Francois Champollion, place de Verdun, 81012 Albi cedex 9 (France); Mauricot, Robert; Navarro, Julien [CEMES, 29 rue Jeanne Marvig, BP 94347, 31055 Toulouse cedex 4 (France); Sekhri, Salem [ENVOI, Cheminement Glueck, 31100 Toulouse (France)

2009-12-15

This study is part of an operation in the framework of treatment and revalorization of IEEE (Informatics, Electronics and related) wastes. It aims to recover the active phosphors in cathode ray tubes (CRTs) and to re-cycle these powders by appropriate treatments as phosphors for mercury-free applications such as plasma display panels, flat lamps, advertising and lighting. The studied waste comes from a large panel of CRTs from any supplier. Several thermo-chemical treatments have been investigated. The removal of zinc sulfide-based phosphors and the recovery of a red phosphor Y{sub 2}O{sub 3}:Eu{sup 3+} has been achieved by one (basic attack) route. The photoluminescence efficiency under VUV excitation of the obtained powders is at most 30% that of a commercial phosphor. The second route (acid attack) appears less promising. It has been established that silicate-based impurities could prevent isolating the yttrium based phosphor.

The use of Syrian bentonite to remove organics and other ions from commercial Syrian phosphoric acid

International Nuclear Information System (INIS)

Khorfan, S.; Abdulbaki, M.; Zein, A.

2006-01-01

Using of activated carbon to remove organic matter from phosphoric acid in uranium and P 2 O 5 extraction units has high cost. A new study was conducted to establish a new material instead of activated carbon. Experiments were carried out on removing organic matter by adsorption on Syrian bentonite. The experiments of the removal of humic acid by Syrian bentonite gave good results and showed that the chemical and thermal activation of bentonite increased the adsorption efficiency. (Authors)

The use of Syrian bentonite to remove organics and other ions from commercial Syrian phosphoric acid

International Nuclear Information System (INIS)

Khorfan, S.; Abdulbaki, M.; Zein, A.

2005-03-01

Using of activated carbon to remove organic matter from phosphoric acid in uranium and P 2 O 5 extraction units has high cost. A new study was conducted to establish a new material instead of activated carbon. Experiments were carried out on removing organic matter by adsorption on Syrian bentonite. The experiments of the removal of humic acid by Syrian bentonite gave good results and showed that the chemical and thermal activation of bentonite increased the adsorption efficiency. (Authors)

Modeling granular phosphor screens by Monte Carlo methods

International Nuclear Information System (INIS)

Liaparinos, Panagiotis F.; Kandarakis, Ioannis S.; Cavouras, Dionisis A.; Delis, Harry B.; Panayiotakis, George S.

2006-01-01

The intrinsic phosphor properties are of significant importance for the performance of phosphor screens used in medical imaging systems. In previous analytical-theoretical and Monte Carlo studies on granular phosphor materials, values of optical properties, and light interaction cross sections were found by fitting to experimental data. These values were then employed for the assessment of phosphor screen imaging performance. However, it was found that, depending on the experimental technique and fitting methodology, the optical parameters of a specific phosphor material varied within a wide range of values, i.e., variations of light scattering with respect to light absorption coefficients were often observed for the same phosphor material. In this study, x-ray and light transport within granular phosphor materials was studied by developing a computational model using Monte Carlo methods. The model was based on the intrinsic physical characteristics of the phosphor. Input values required to feed the model can be easily obtained from tabulated data. The complex refractive index was introduced and microscopic probabilities for light interactions were produced, using Mie scattering theory. Model validation was carried out by comparing model results on x-ray and light parameters (x-ray absorption, statistical fluctuations in the x-ray to light conversion process, number of emitted light photons, output light spatial distribution) with previous published experimental data on Gd 2 O 2 S:Tb phosphor material (Kodak Min-R screen). Results showed the dependence of the modulation transfer function (MTF) on phosphor grain size and material packing density. It was predicted that granular Gd 2 O 2 S:Tb screens of high packing density and small grain size may exhibit considerably better resolution and light emission properties than the conventional Gd 2 O 2 S:Tb screens, under similar conditions (x-ray incident energy, screen thickness)

Uranium recovery from wet-process phosphoric acid

International Nuclear Information System (INIS)

McCullough, J.F.; Phillips, J.F. Jr.; Tate, L.R.

1979-01-01

A method of recovering uranium from wet-process phosphoric acid is claimed where the acid is treated with a mixture of an ammonium salt or ammonia, a reducing agent, and then a miscible solvent. Solids are separated from the phosphoric acid liquid phase. The solid consists of a mixture of metal phosphates and uranium. It is washed free of adhering phosphoric acid with fresh miscible solvent. The solid is dried and dissolved in acid whereupon uranium is recovered from the solution. Miscible solvent and water are distilled away from the phosphoric acid. The distillate is rectified and water discarded. All miscible solvent is recovered for recycle. 5 claims

Microbial β-etherases and glutathione lyases for lignin valorisation in biorefineries: current state and future perspectives.

Science.gov (United States)

Husarcíková, Jana; Voß, Hauke; Domínguez de María, Pablo; Schallmey, Anett

2018-05-04

Lignin is the major aromatic biopolymer in nature, and it is considered a valuable feedstock for the future supply of aromatics. Hence, its valorisation in biorefineries is of high importance, and various chemical and enzymatic approaches for lignin depolymerisation have been reported. Among the enzymes known to act on lignin, β-etherases offer the possibility for a selective cleavage of the β-O-4 aryl ether bonds present in lignin. These enzymes, together with glutathione lyases, catalyse a reductive, glutathione-dependent ether bond cleavage displaying high stereospecificity. β-Etherases and glutathione lyases both belong to the superfamily of glutathione transferases, and several structures have been solved recently. Additionally, different approaches for their application in lignin valorisation have been reported in the last years. This review gives an overview on the current knowledge on β-etherases and glutathione lyases, their biochemical and structural features, and critically discusses their potential for application in biorefineries.

Removal of uranium(VI) from aqueous solutions by new phosphorus-containing carbon spheres synthesized via one-step hydrothermal carbonization of glucose in the presence of phosphoric acid

International Nuclear Information System (INIS)

Zhi-bin Zhang; East China Institute of Technology, Fuzhou; China University of Geosciences, Wuhan; Zhi-wei Zhou; Xiao-hong Cao; Yun-hai Liu; Guo-xuan Xiong; East China Institute of Technology, Fuzhou; Ping Liang; East China Institute of Technology, Fuzhou; China University of Geosciences, Wuhan

2014-01-01

The novel phosphorus-rich hydrothermal carbon spheres (HCSs-PO 4 ) have been synthesized via one-step hydrothermal carbonization of glucose in the presence of phosphoric acid. The textural and surface chemistry properties were characterized using Boehm titrations, scanning electron microscopy and Fourier transform infrared spectrometer. The content of oxygen-containing functional groups on the surface of HCSs increased from 0.053 to 1.009 mmol g -1 by phosphate group modification. The adsorption ability of HCSsPO 4 has been explored for the removal of uranium from aqueous solutions. The adsorption kinetic data were best described by the pseudo-second-order equation. Adsorption process could be well defined by the Langmuir isotherm, the adsorption capacity of HCSs increased from 80.00 to 285.70 mg g -1 after phosphate group modification. And thermodynamic parameters indicated the adsorption process was feasible,endothermic and spontaneous. Selective adsorption studies showed that the HCSs-PO 4 could selectively remove U(VI), and the selectivity coefficients had been improved in the presence of co-existing ions, Na(I), Ni(II), Sr(II), Mn(II), Mg(II) and Zn(II). Complete removal (99.9 %) of U(VI) from 1.0 L industry wastewater containing 15.0 mg U(VI) ions was possible with 12.0 g HCSs-PO 4 . (author)

Pathways of human development and carbon emissions embodied in trade

Science.gov (United States)

Steinberger, Julia K.; Timmons Roberts, J.; Peters, Glen P.; Baiocchi, Giovanni

2012-02-01

It has long been assumed that human development depends on economic growth, that national economic expansion in turn requires greater energy use and, therefore, increased greenhouse-gas emissions. These interdependences are the topic of current research. Scarcely explored, however, is the impact of international trade: although some nations develop socio-economically and import high-embodied-carbon products, it is likely that carbon-exporting countries gain significantly fewer benefits. Here, we use new consumption-based measures of national carbon emissions to explore how the relationship between human development and carbon changes when we adjust national emission rates for trade. Without such adjustment of emissions, some nations seem to be getting far better development `bang' for the carbon `buck' than others, who are showing scant gains for disproportionate shares of global emissions. Adjusting for the transfer of emissions through trade explains many of these outliers, but shows that further socio-economic benefits are accruing to carbon-importing rather than carbon-exporting countries. We also find that high life expectancies are compatible with low carbon emissions but high incomes are not. Finally, we see that, despite strong international trends, there is no deterministic industrial development trajectory: there is great diversity in pathways, and national histories do not necessarily follow the global trends.

Pathways of organic carbon oxidation in three continental margin sediments

DEFF Research Database (Denmark)

Canfield, Donald Eugene; Jørgensen, Bo Barker; Fossing, Henrik

1993-01-01

We have combined several different methodologies to quantify rates of organic carbon mineralization by the various electron acceptors in sediments from the coast of Denmark and Norway. Rates of NH4+ and Sigma CO2 liberation sediment incubations were used with O2 penetration depths to conclude...... that O2 respiration accounted for only between 3.6-17.4% of the total organic carbon oxidation. Dentrification was limited to a narrow zone just below the depth of O2 penetration, and was not a major carbon oxidation pathway. The processes of Fe reduction, Mn reduction and sulfate reduction dominated...... organic carbon mineralization, but their relative significance varied depending on the sediment. Where high concentrations of Mn-oxide were found (3-4 wt% Mn), only Mn reduction occurred. With lower Mn oxide concentrations more typical of coastal sediments, Fe reduction and sulfate reduction were most...

Phosphorous-Containing Polymers for Regenerative Medicine

Science.gov (United States)

Watson, Brendan M.; Kasper, F. Kurtis; Mikos, Antonios G.

2014-01-01

Disease and injury have resulted in a large, unmet need for functional tissue replacements. Polymeric scaffolds can be used to deliver cells and bioactive signals to address this need for regenerating damaged tissue. Phosphorous-containing polymers have been implemented to improve and accelerate the formation of native tissue both by mimicking the native role of phosphorous groups in the body and by attachment of other bioactive molecules. This manuscript reviews the synthesis, properties, and performance of phosphorous-containing polymers that can be useful in regenerative medicine applications. PMID:24565855

Complexity in Acid?Base Titrations: Multimer Formation Between Phosphoric Acids and Imines

OpenAIRE

Malm, Christian; Kim, Heejae; Wagner, Manfred; Hunger, Johannes

2017-01-01

Abstract Solutions of Br?nsted acids with bases in aprotic solvents are not only common model systems to study the fundamentals of proton transfer pathways but are also highly relevant to Br?nsted acid catalysis. Despite their importance the light nature of the proton makes characterization of acid?base aggregates challenging. Here, we track such acid?base interactions over a broad range of relative compositions between diphenyl phosphoric acid and the base quinaldine in dichloromethane, by u...

Highly Active and Specific Tyrosine Ammonia-Lyases from Diverse Origins Enable Enhanced Production of Aromatic Compounds in Bacteria and Saccharomyces cerevisiae

DEFF Research Database (Denmark)

Jendresen, Christian Bille; Stahlhut, Steen Gustav; Li, Mingji

2015-01-01

Phenylalanine and tyrosine ammonia-lyases form cinnamic acid and p-coumaric acid, which are precursors of a wide range of aromatic compounds of biotechnological interest. Lack of highly active and specific tyrosine ammonia-lyases has previously been a limitation in metabolic engineering approaches...

Optimization of Preparation Program for Biomass Based Porous Active Carbon by Response Surface Methodology Based on Adsorptive Property

Directory of Open Access Journals (Sweden)

ZHANG Hao

2017-06-01

Full Text Available With waste walnut shell as raw material, biomass based porous active carbon was made by microwave oven method. The effects of microwave power, activation time and mass fraction of phosphoric acid on adsorptive property of biomass based porous active carbon in the process of physical activation of active carbon precursor were studied by response surface method and numerical simulation method, the preparation plan of biomass based porous active carbon was optimized, and the optimal biomass based porous active carbon property was characterized. The results show that three factors affect the adsorptive property of biomass based porous active carbon, but the effect of microwave power is obviously more significant than that of mass fraction of phosphoric acid, and the effect of mass fraction of phosphoric acid is more significant than that of activation time. The optimized preparation conditions are:microwave power is 746W, activation time is 11.2min and mass fraction of phosphoric acid is 85.9% in the process of physical activation of activated carbon precursor by microwave heating method. For the optimal biomass based porous active carbon, the adsorption value of iodine is 1074.57mg/g, adsorption value of methylene blue is 294.4mL/g and gain rate is 52.1%.

Pectinolytic bacteria and their secreted pectate lyases: agents for the maceration and solubilization of phytomass for fuels production

Energy Technology Data Exchange (ETDEWEB)

Preston, J.F. III; Rice, J.D.; Chow, M.C. (Florida Univ., Gainesville, FL (United States). Dept. of Microbiology and Cell Science)

1993-01-01

The objectives of this research have been to identify the pectinolytic enzymes secreted by bacteria and apply these towards the enhanced maceration and solubilization of plant material, focusing on the pectate lyases secreted by the phytopathogenic strains of Erwinia chrysanthemi, the ruminant resident Lachnospira multiparus, and the wood digestor isolate, Clostridium populeti. An HPLC approach has been developed that permits the kinetic analysis of each enzyme with respect to the formation of individual products during the pectate depolymerization process. This approach has demonstrated that each of these organisms secretes a nonrandom trimer-generating pectate lyase with a combination of endolytic and exolytic depolymerizing mechanisms. Two different strains of E. chrysanthemi secrete a battery of pectate lyases that include random endolytic as well as nonrandom dimer - and nonrandom trimer-generating endolytic/exolytic mechanisms. (author)

Catalytic Mechanisms and Biocatalytic Applications of Aspartate and Methylaspartate Ammonia Lyases

NARCIS (Netherlands)

de Villiers, Marianne; Veetil, Vinod Puthan; Raj, Hans; de Villiers, Jandre; Poelarends, Gerrit J.

2012-01-01

Ammonia lyases catalyze the formation of alpha-beta-unsaturated bonds by the elimination of ammonia from their substrates. This conceptually straightforward reaction has been the emphasis of many studies, with the main focus on the catalytic mechanism of these enzymes and/or the use of these enzymes

Pretreatment of industrial phosphoric acid by Algerian filter-aids

International Nuclear Information System (INIS)

Mellah, A.; Setti, Louisa; Chegrouche, Salah

1993-01-01

The present work involves the filtration of industrial phosphoric acid by different filter-aids such as kieselguhr, celite and bleaching clay. The retention of substances contained in wet phosphoric acid was determined using the three filter-aids. Thus, the phosphoric acid, obtained by filtration on kieselguhr has the same specifications as technical phosphoric acid produced by Rhone-Poulenc (France) as standard

Uranium extraction from phosphoric acid

International Nuclear Information System (INIS)

Araujo Figueiredo, C. de

1984-01-01

The recovery of uranium from phosphoric liquor by two extraction process is studied. First, uranium is reduced to tetravalent condition and is extracted by dioctypyrophosphoric acid. The re-extraction is made by concentrated phosphoric acid with an oxidizing agent. The re-extract is submitted to the second process and uranium is extracted by di-ethylhexilphosphoric acid and trioctylphosphine oxide. (M.A.C.) [pt

S1P lyase in thymic perivascular spaces promotes egress of mature thymocytes via up-regulation of S1P receptor 1.

Science.gov (United States)

Maeda, Yasuhiro; Yagi, Hideki; Takemoto, Kana; Utsumi, Hiroyuki; Fukunari, Atsushi; Sugahara, Kunio; Masuko, Takashi; Chiba, Kenji

2014-05-01

Sphingosine 1-phosphate (S1P) and S1P receptor 1 (S1P1) play an important role in the egress of mature CD4 or CD8 single-positive (SP) thymocytes from the thymus. Fingolimod hydrochloride (FTY720), an S1P1 functional antagonist, induced significant accumulation of CD62L(high)CD69(low) mature SP thymocytes in the thymic medulla. Immunohistochemical staining using anti-S1P1 antibody revealed that S1P1 is predominantly expressed on thymocytes in the thymic medulla and is strongly down-regulated even at 3h after FTY720 administration. 2-Acetyl-4-tetrahydroxybutylimidazole (THI), an S1P lyase inhibitor, also induced accumulation of mature SP thymocytes in the thymic medulla with an enlargement of the perivascular spaces (PVS). At 6h after THI administration, S1P1-expressing thymocytes reduced partially as if to form clusters and hardly existed in the proximity of CD31-expressing blood vessels in the thymic medulla, suggesting S1P lyase expression in the cells constructing thymic medullary PVS. To determine the cells expressing S1P lyase in the thymus, we newly established a mAb (YK19-2) specific for mouse S1P lyase. Immunohistochemical staining with YK19-2 revealed that S1P lyase is predominantly expressed in non-lymphoid thymic stromal cells in the thymic medulla. In the thymic medullary PVS, S1P lyase was expressed in ER-TR7-positive cells (reticular fibroblasts and pericytes) and CD31-positive vascular endothelial cells. Our findings suggest that S1P lyase expressed in the thymic medullary PVS keeps the tissue S1P concentration low around the vessels and promotes thymic egress via up-regulation of S1P1.

Sugar-cane juice induces pectin lyase and polygalacturonase in Penicillium griseoroseum

Directory of Open Access Journals (Sweden)

Minussi Rosana Cristina

1998-01-01

Full Text Available The use of other inducers as substitutes for pectin was studied aiming to reduce the production costs of pectic enzymes. The effects of sugar-cane juice on the production of pectin lyase (PL and polygalacturonase (PG by Penicillium griseoroseum were investigated. The fungus was cultured in a mineral medium (pH 6.3 in a rotary shaker (150 rpm for 48 h at 25oC. Culture media were supplemented with yeast extract and sucrose or sugar-cane juice. Sugar-cane juice added singly to the medium promoted higher PL activity and mycelial dry weight when compared to pectin and the use of sugar-cane juice and yeast extract yielded levels of PG activity that were similar to those obtained with sucrose-yeast extract or pectin. The results indicated that, even at low concentrations, sugar-cane juice was capable of inducing pectin lyase and polygalacturonase with no cellulase activity in P. griseoroseum.

Phosphate Phosphors for Solid-State Lighting

CERN Document Server

Shinde, Kartik N; Swart, H C; Park, Kyeongsoon

2012-01-01

The idea for this book arose out of the realization that, although excellent surveys and a phosphor handbook are available, there is no single source covering the area of phosphate based phosphors especially for lamp industry. Moreover, as this field gets only limited attention in most general books on luminescence, there is a clear need for a book in which attention is specifically directed toward this rapidly growing field of solid state lighting and its many applications. This book is aimed at providing a sound introduction to the synthesis and optical characterization of phosphate phosphor for undergraduate and graduate students as well as teachers and researchers. The book provides guidance through the multidisciplinary field of solid state lighting specially phosphate phosphors for beginners, scientists and engineers from universities, research organizations, and especially industry. In order to make it useful for a wide audience, both fundamentals and applications are discussed, together.

Crystallization and preliminary X-ray analysis of argininosuccinate lyase from Streptococcus mutans

International Nuclear Information System (INIS)

Cao, Yan-Li; Li, Gui-Lan; Wang, Kai-Tuo; Zhang, Hong-Yin; Li, Lan-Fen

2011-01-01

Crystals of argininosuccinate lyase from S. mutans were obtained and X-ray data were collected to 2.5 Å resolution in space group R3. Argininosuccinate lyase (ASL) is an important enzyme in arginine synthesis and the urea cycle, which are highly conserved from bacteria to eukaryotes. The gene encoding Streptococcus mutans ASL (smASL) was amplified and cloned into expression vector pET28a. The recombinant smASL protein was expressed in a soluble form in Escherichia coli strain BL21 (DE3) and purified to homogeneity by two-step column chromatography. Crystals suitable for X-ray analysis were obtained and X-ray diffraction data were collected to a resolution of 2.5 Å. The crystals belonged to space group R3, with unit-cell parameters a = b = 254.5, c = 78.3 Å

X-ray investigation of phosphors for black-white television

International Nuclear Information System (INIS)

Lazowy, B.

1975-01-01

The investigations of phosphors made by means of the powder diffraction method are presented. The diffraction patterns has been obtained by means of the DRON-1 diffractometer, using the Ksub(α) copper radiation and a nickel filter. Reflex intensity was estimated, indexing was made and lattice constants for particular structure types were calculated. The objects of the investigations were the phosphors from various firms of white luminescence and home phosphors of white, blue and yellow luminescence. On the base of the results it was found that all investigated phosphors of yellow luminescence belonged to the hexagonal system. These phosphors, depending on baking conditions, have structure of regular symmetry. The phosphors of white luminescence are a mixture of hexagonal and regular phase and any changes in elementary cell sizes were not observed. All phosphors of white luminescence have analogous structure, positions of all reflexes are identical, negligible differences in their intensities occur only, which proves somewhat different arrangement of atoms in mixed crystals. (author)

Synergistic dynamics of nitrogen and phosphorous influences lipid productivity in Chlorella minutissima for biodiesel production.

Science.gov (United States)

Arora, Neha; Patel, Alok; Pruthi, Parul A; Pruthi, Vikas

2016-08-01

The study synergistically optimized nitrogen and phosphorous concentrations for attainment of maximum lipid productivity in Chlorella minutissima. Nitrogen and phosphorous limited cells (N(L)P(L)) showed maximum lipid productivity (49.1±0.41mg/L/d), 1.47 folds higher than control. Nitrogen depletion resulted in reduced cell size with large sized lipid droplets encompassing most of the intracellular space while discrete lipid bodies were observed under nitrogen sufficiency. Synergistic N/P starvations showed more prominent effect on photosynthetic pigments as to individual deprivations. Phosphorous deficiency along with N starvation exhibited 17.12% decline in carbohydrate while no change in nitrogen sufficient cells were recorded. The optimum N(L)P(L) concentration showed balance between biomass and lipid by maintaining intermediate cell size, pigments, carbohydrate and proteins. FAME profile showed C14-C18 carbon chains in N(L)P(L) cells with biodiesel properties comparable to plant oil methyl esters. Hence, synergistic N/P limitation was effective for enhancing lipid productivity with reduced consumption of nutrients. Copyright © 2016 Elsevier Ltd. All rights reserved.

Pretreatment of phosphoric acid for uranium recovery by the wet phosphoric acid process

International Nuclear Information System (INIS)

Chern, S.L.P.; Chen, Y.C.L.; Chang, S.S.H.; Kuo, T.S.; Ting, G.C.M.

1980-01-01

The proposal deals with reprocessing of phosphoric acid arising from uranium separation according to the wet phosphoric acid process and being intended for recycling. In detail, the sludge will be removed by means of an inclined separating device containing corrugated plates, then the organic impurities are washed out with kerosene in suitable facilities, and the crude phase remaining in the settling tank will be separated from the kerosene in a separating centrifuge. The method has only got low cost of installation. (UWI) [de

Long lasting behavior of Gd2O2S:Eu3+ phosphor synthesized by hydrothermal routine

International Nuclear Information System (INIS)

Hang Tao; Liu Qun; Mao Dali; Chang Chengkang

2008-01-01

This paper reports the detailed preparation process and afterglow properties of Eu 3+ activated long lasting Gd 2 O 2 S phosphor by hydrothermal routine. Rod-like Gd(OH) 3 were firstly synthesized by hydrothermal method to serve as the precursor. Long lasting Gd 2 O 2 S:Eu 3+ ,Ti 4+ ,Mg 2+ phosphor was obtained by calcinating the precursor with co-activators and S powder. It was found from the results that the hydrothermally prepared Gd(OH) 3 revealed a rod-like morphology, while the calcinated Gd 2 O 2 S:Eu 3+ ,Ti 4+ ,Mg 2+ phosphor showed a round granular shape. The morphological change can be explained by the etching effect of the melt that was formed by the carbonate and S powder during the high temperature calcination. The obtained Gd 2 O 2 S:Eu 3+ ,Ti 4+ ,Mg 2+ phosphor produced a red emission upon 243 nm UV excitation, which is a typical emission of Eu 3+ from 5 D j to 7 F j states. Long lasting behavior was observed after the UV source was switched off, due to the formation of electron traps with suitable trap depth within the matrix by the codoped Ti 4+ and Mg 2+ ions

Cloning and Sequence Analysis of Vibrio halioticoli Genes Encoding Three Types of Polyguluronate Lyase.

Science.gov (United States)

Sugimura; Sawabe; Ezura

2000-01-01

The alginate lyase-coding genes of Vibrio halioticoli IAM 14596(T), which was isolated from the gut of the abalone Haliotis discus hannai, were cloned using plasmid vector pUC 18, and expressed in Escherichia coli. Three alginate lyase-positive clones, pVHB, pVHC, and pVHE, were obtained, and all clones expressed the enzyme activity specific for polyguluronate. Three genes, alyVG1, alyVG2, and alyVG3, encoding polyguluronate lyase were sequenced: alyVG1 from pVHB was composed of a 1056-bp open reading frame (ORF) encoding 352 amino acid residues; alyVG2 gene from pVHC was composed of a 993-bp ORF encoding 331 amino acid residues; and alyVG3 gene from pVHE was composed of a 705-bp ORF encoding 235 amino acid residues. Comparison of nucleotide and deduced amino acid sequences among AlyVG1, AlyVG2, and AlyVG3 revealed low homologies. The identity value between AlyVG1 and AlyVG2 was 18.7%, and that between AlyVG2 and AlyVG3 was 17.0%. A higher identity value (26.0%) was observed between AlyVG1 and AlyVG3. Sequence comparison among known polyguluronate lyases including AlyVG1, AlyVG2, and AlyVG3 also did not reveal an identical region in these sequences. However, AlyVG1 showed the highest identity value (36.2%) and the highest similarity (73.3%) to AlyA from Klebsiella pneumoniae. A consensus region comprising nine amino acid (YFKAGXYXQ) in the carboxy-terminal region previously reported by Mallisard and colleagues was observed only in AlyVG1 and AlyVG2.

Compact fluorescent lamp phosphors in accidental radiation monitoring

International Nuclear Information System (INIS)

Murthy, K. V. R.; Pallavi, S. P.; Ghildiyal, R.; Parmar, M. C.; Patel, Y. S.; Ravi Kumar, V.; Sai Prasad, A. S.; Natarajan, V.; Page, A. G.

2006-01-01

The application of lamp phosphors for accidental dosimetry is a new concept. Since the materials used in fluorescent lamps are good photo luminescent materials, if one can either use the inherent defects present in the phosphor or add suitable modifiers to induce thermoluminescence (TL) in these phosphors, then the device (fluorescent lamp) can be used as an accidental dosemeter. In continuation of our search for a suitable phosphor material, which can serve both as an efficient lamp phosphor and as a good radiation monitoring device, detailed examination has been carried out on cerium and terbium-doped lanthanum phosphate material. A 90 Sr beta source with 50 mCi strength (1.85 GBq) was used as the irradiation source for TL studies. The TL response as a function of dose received was examined for all phosphors used and it was observed that the intensity of the TL peak vs. dose received was a linear function in the dose range 0.1-200 Gy in each case. Incidentally LaPO 4 :Ce,Tb is a component of the compact fluorescent lamp marketed recently as an energy bright light source. Besides having very good luminescence efficiency, good dosimetric properties of these phosphors render them useful for their use in accidental dosimetry also. (authors)

Diagenetic pathways in deposits of cool- and cold-water carbonate factories

Science.gov (United States)

Frank, T. D.; James, N. P.

2017-12-01

This investigation integrates sedimentological, petrographic, and geochemical observations from modern and ancient heterozoan carbonate deposits that formed at temperate to polar latitudes with the aim of evaluating diagenetic pathways characteristic of these systems. These factories operate under conditions distinct from those of photozoan counterparts. Lower temperatures, higher trophic resources, lower carbonate saturation states, and strong seasonality govern not only the nature of carbonate communities, but also how deposits translate into the rock record. In these settings, carbonate production is entirely biogenic, assemblages are of low diversity, and there are no significant calcareous phototrophs. Aragonitic taxa may be present in living communities, but allochems rapidly disappear via dissolution. Carbonate producers are not capable of building rigid frameworks, so their deposits accumulate as sands and gravels and are prone to winnowing and reworking. Low production rates lead to long seafloor residence times (1000s of years) for grains, which undergo physical reworking, dissolution, and repeated infestation by endolithic borers. Microborings remain empty, increasing grain susceptibility to disintegration. Intergranular cementation on the seafloor is rare and restricted to hardgrounds. Periods of subaerial exposure do not leave traces of meteoric alteration. Results show that the deposits of heterozoan carbonate factories tend enter the geologic record as taphonomic remnants, namely reworked, unconsolidated sands and gravels with low diagenetic potential. During burial, physical and chemical compaction produce limestones with tightly packed, grain-supported fabrics, often with grains in sutured contact. Significant cementation is associated with the deep burial realm. Results reveal a dramatically different diagenetic pathway than is typical for deposits of tropical photozoan factories, in which significant recrystallization and lithification occur on

A 5-methylcytosine DNA glycosylase/lyase demethylates the retrotransposon Tos17 and promotes its transposition in rice

KAUST Repository

La, Honggui; Ding, Bo; Mishra, Gyan Prakash; Zhou, Bo; Yang, Hongmei; Bellizzi, Maria Del Rosario; Chen, Songbiao; Meyers, Blake C.; Peng, Zhaohua; Zhu, Jian-Kang; Wang, Guoliang

2011-01-01

DNA 5-methylcytosine (5-meC) is an important epigenetic mark for transcriptional gene silencing in many eukaryotes. In Arabidopsis, 5-meC DNA glycosylase/lyases actively remove 5-meC to counter-act transcriptional gene silencing in a locus-specific manner, and have been suggested to maintain the expression of transposons. However, it is unclear whether plant DNA demethylases can promote the transposition of transposons. Here we report the functional characterization of the DNA glycosylase/lyase DNG701 in rice. DNG701 encodes a large (1,812 amino acid residues) DNA glycosylase domain protein. Recombinant DNG701 protein showed 5-meC DNA glycosylase and lyase activities in vitro. Knockout or knockdown of DNG701 in rice plants led to DNA hypermethylation and reduced expression of the retrotransposon Tos17. Tos17 showed less transposition in calli derived from dng701 knockout mutant seeds compared with that in wild-type calli. Overexpression of DNG701 in both rice calli and transgenic plants substantially reduced DNA methylation levels of Tos17 and enhanced its expression. The overexpression also led to more frequent transposition of Tos17 in calli. Our results demonstrate that rice DNG701 is a 5-meC DNA glycosylase/lyase responsible for the demethylation of Tos17 and this DNA demethylase plays a critical role in promoting Tos17 transposition in rice calli.

A 5-methylcytosine DNA glycosylase/lyase demethylates the retrotransposon Tos17 and promotes its transposition in rice

KAUST Repository

La, Honggui

2011-09-06

DNA 5-methylcytosine (5-meC) is an important epigenetic mark for transcriptional gene silencing in many eukaryotes. In Arabidopsis, 5-meC DNA glycosylase/lyases actively remove 5-meC to counter-act transcriptional gene silencing in a locus-specific manner, and have been suggested to maintain the expression of transposons. However, it is unclear whether plant DNA demethylases can promote the transposition of transposons. Here we report the functional characterization of the DNA glycosylase/lyase DNG701 in rice. DNG701 encodes a large (1,812 amino acid residues) DNA glycosylase domain protein. Recombinant DNG701 protein showed 5-meC DNA glycosylase and lyase activities in vitro. Knockout or knockdown of DNG701 in rice plants led to DNA hypermethylation and reduced expression of the retrotransposon Tos17. Tos17 showed less transposition in calli derived from dng701 knockout mutant seeds compared with that in wild-type calli. Overexpression of DNG701 in both rice calli and transgenic plants substantially reduced DNA methylation levels of Tos17 and enhanced its expression. The overexpression also led to more frequent transposition of Tos17 in calli. Our results demonstrate that rice DNG701 is a 5-meC DNA glycosylase/lyase responsible for the demethylation of Tos17 and this DNA demethylase plays a critical role in promoting Tos17 transposition in rice calli.

Engineering methylaspartate ammonia lyase for the asymmetric synthesis of unnatural amino acids

NARCIS (Netherlands)

Raj, Hans; Szymanski, Wiktor; de Villiers, Jandre; Rozeboom, Henriëtte J.; Puthan Veetil, Vinod; Reis, Carlos R.; Villiers, Marianne de; Dekker, Frank J.; Wildeman, Stefaan de; Quax, Wim J.; Thunnissen, Andy-Mark W.H.; Feringa, Ben L.; Janssen, Dick B.; Poelarends, Gerrit J.

The redesign of enzymes to produce catalysts for a predefined transformation remains a major challenge in protein engineering. Here, we describe the structure-based engineering of methylaspartate ammonia lyase (which in nature catalyses the conversion of 3-methylaspartate to ammonia and

Potential role of multiple carbon fixation pathways during lipid accumulation in Phaeodactylum tricornutum

Directory of Open Access Journals (Sweden)

Valenzuela Jacob

2012-06-01

Full Text Available Abstract Background Phaeodactylum tricornutum is a unicellular diatom in the class Bacillariophyceae. The full genome has been sequenced (P. tricornutum gene expression profiles during nutrient-deprivation and lipid-accumulation, cell cultures were grown with a nitrate to phosphate ratio of 20:1 (N:P and whole-genome transcripts were monitored over time via RNA-sequence determination. Results The specific Nile Red (NR fluorescence (NR fluorescence per cell increased over time; however, the increase in NR fluorescence was initiated before external nitrate was completely exhausted. Exogenous phosphate was depleted before nitrate, and these results indicated that the depletion of exogenous phosphate might be an early trigger for lipid accumulation that is magnified upon nitrate depletion. As expected, many of the genes associated with nitrate and phosphate utilization were up-expressed. The diatom-specific cyclins cyc7 and cyc10 were down-expressed during the nutrient-deplete state, and cyclin B1 was up-expressed during lipid-accumulation after growth cessation. While many of the genes associated with the C3 pathway for photosynthetic carbon reduction were not significantly altered, genes involved in a putative C4 pathway for photosynthetic carbon assimilation were up-expressed as the cells depleted nitrate, phosphate, and exogenous dissolved inorganic carbon (DIC levels. P. tricornutum has multiple, putative carbonic anhydrases, but only two were significantly up-expressed (2-fold and 4-fold at the last time point when exogenous DIC levels had increased after the cessation of growth. Alternative pathways that could utilize HCO3- were also suggested by the gene expression profiles (e.g., putative propionyl-CoA and methylmalonyl-CoA decarboxylases. Conclusions The results indicate that P. tricornutum continued carbon dioxide reduction when population growth was arrested and different carbon-concentrating mechanisms were used dependent upon exogenous

Effect of grinding on photostimuable phosphors for x-ray screens

International Nuclear Information System (INIS)

Rao, R.B.

1988-01-01

Luminescence efficiency of a phosphor can be improved by minimizing the energy losses during excitation. The loss of excitation energy in the case of powdered samples is mainly due to scattering of incident radiation by the particles of phosphor. Thus, while considering the industrial applications of polycrystalline phosphors in lamps, screens, paints, etc., the effect of particle size on the light output has to be specially studied. It is very well established that the radiographic imaging with photostimuable (PS) phosphors has many advantages over conventional photographic film screens. In the new type of computer radiography, PS phosphors are to be used as memory materials for temporary storage of the x-ray image. Eu(2+) doped barium fluorohalide phosphors are most suitable for this purpose. The spatial resolution from the image plate can be improved to a certain extent with phosphors comprising fine particles. The fineness of the particles can be achieved by various means such as grinding, fast cooling after firing or incorporation of some flux materials during the firing processes. But the efficiency of the phosphor deteriorates with grinding. Fast cooling is a complicated process in the case of Eu(2+) doped phosphors. Incorporation of flux materials may change the characteristics of phosphor materials. In the present investigation, effect of grinding (ball milling) on particle size distribution, shape of the particles and luminescent properties of BaFCl phosphors have been studied

High efficiency nitride based phosphores for white LEDs

NARCIS (Netherlands)

Li, Yuan Qiang; Hintzen, H.T.J.M.

2008-01-01

In this overview paper, novel rare-earth doped silicon nitride based phosphors for white LEDs applications have been demonstrated. The luminescence properties of orange-red-emitting phosphors (M2Si5N8:Eu2+) and green-to-yellow emitting phosphors (MSi2N2O2:Eu2+, M = Ca, Sr, Ba) are discussed in

Reprogramming One-Carbon Metabolic Pathways To Decouple l-Serine Catabolism from Cell Growth in Corynebacterium glutamicum.

Science.gov (United States)

Zhang, Yun; Shang, Xiuling; Lai, Shujuan; Zhang, Yu; Hu, Qitiao; Chai, Xin; Wang, Bo; Liu, Shuwen; Wen, Tingyi

2018-02-16

l-Serine, the principal one-carbon source for DNA biosynthesis, is difficult for microorganisms to accumulate due to the coupling of l-serine catabolism and microbial growth. Here, we reprogrammed the one-carbon unit metabolic pathways in Corynebacterium glutamicum to decouple l-serine catabolism from cell growth. In silico model-based simulation showed a negative influence on glyA-encoding serine hydroxymethyltransferase flux with l-serine productivity. Attenuation of glyA transcription resulted in increased l-serine accumulation, and a decrease in purine pools, poor growth and longer cell shapes. The gcvTHP-encoded glycine cleavage (Gcv) system from Escherichia coli was introduced into C. glutamicum, allowing glycine-derived 13 CH 2 to be assimilated into intracellular purine synthesis, which resulted in an increased amount of one-carbon units. Gcv introduction not only restored cell viability and morphology but also increased l-serine accumulation. Moreover, comparative proteomic analysis indicated that abundance changes of the enzymes involved in one-carbon unit cycles might be responsible for maintaining one-carbon unit homeostasis. Reprogramming of the one-carbon metabolic pathways allowed cells to reach a comparable growth rate to accumulate 13.21 g/L l-serine by fed-batch fermentation in minimal medium. This novel strategy provides new insights into the regulation of cellular properties and essential metabolite accumulation by introducing an extrinsic pathway.

Tm3+ activated lanthanum phosphate: a blue PDP phosphor

International Nuclear Information System (INIS)

Rao, R.P.

2005-01-01

Plasma display panels (PDPs) are gaining attention due to their high performance and scalability as a medium for large format TVs. The performance and life of a PDP strongly depends upon the nature of phosphors. Currently, Eu 2+ activated barium magnesium aluminate (BAM) is being used as a blue component. Because of its low life, efforts are being made to explore new blue emitting phosphors. One of the alternatives to BAM is Tm 3+ activated lanthanum phosphate (LPTM) phosphor. LPTM phosphor samples are prepared by a solid-state as well as sol-gel process in presence of flux. The phosphor of the present investigation, having uniform and spherical shape particles in the range of 0.1-2 μm, is appropriate for thin phosphor screens required for PDP applications. It exhibits a narrow band emission in the blue region, peaking at 452 nm and also a number of narrow bands in the UV region when excited by 147 and 173 nm radiation from a xenon gas mixture. Various possible transitions responsible for UV and visible emission from Tm 3+ ion are presented. These phosphors also exhibit good color saturation and better stability when excited with VUV radiation. To achieve higher brightness, they are blended with other UV excited blue emitting phosphors such as BAM. Results related to morphology, excitation, after glow decay, emission and degradation of these phosphors in the powder form as well as in plasma display panels are presented and discussed

Genetic and molecular analyses of Escherichia coli N-acetylneuraminate lyase gene.

OpenAIRE

Kawakami, B; Kudo, T; Narahashi, Y; Horikoshi, K

1986-01-01

Two plasmids containing the N-acetylneuraminate lyase (NALase) gene (nanA) of Escherichia coli, pNL1 and pNL4, were constructed. Immunoprecipitation analysis indicated that the 35,000-dalton protein encoded in pNL4 was NALase. The synthesis of NALase in E. coli carrying these plasmids was constitutive.

Method of recovering phosphoric acid type decontaminating electrolytes by electrodeposition

International Nuclear Information System (INIS)

Sasaki, Takashi; Wada, Koichi; Kobayashi, Toshio.

1985-01-01

Purpose: To recoving phosphoric acid type highly concentrated decontaminating liquid used for the electrolytic decontamination of contaminated equipments, components, etc in nuclear power plants or the like through electrodeposition by diaphragm electrolysis. Method: Before supplying phosphoric acid decontaminating liquid at high concentration used in the electrolytic decontaminating step to an electrodeposition recovering tank, phosphoric acid in the decontaminating electrolyte is extracted with solvents and decomposed liquid extracts (electrolyte reduced with the phosphoric acid component) are supplied to the cathode chamber of the electrodeposition recovering tank, where phosphoric acid is back-extracted with water from the solvents after extraction of phosphoric acid. Then, the back-extracted liquids (aqueous phosphoric acid solution scarcely containing metal ions) are sent to the anode chamber of the electrodeposition recovering tank. Metal ions in the liquid are captured by electrodeposition in the cathode chamber, as well as phosphoric acid in the liquids is concentrated to the initial concentration of the electrolyte in the anode chamber for reuse as the decontaminating electrolyte. As the phosphoric acid extracting agent used in the electrodeposition recovering step for the decontaminating electrolyte, water-insoluble and non-combustible tributyl phosphate (TBP) is most effective. (Horiuchi, T.)

Mechanism of Cytochrome P450 17A1-Catalyzed Hydroxylase and Lyase Reactions

DEFF Research Database (Denmark)

Bonomo, Silvia; Jorgensen, Flemming Steen; Olsen, Lars

2017-01-01

Cytochrome P450 17A1 (CYP17A1) catalyzes C17 hydroxylation of pregnenolone and progesterone and the subsequent C17–C20 bond cleavage (lyase reaction) to form androgen precursors. Compound I (Cpd I) and peroxo anion (POA) are the heme-reactive species underlying the two reactions. We have characte...... the concept that the selectivity of the steroidogenic CYPs is ruled by direct interactions with the enzyme, in contrast to the selectivity of drug-metabolizing CYPs, where the reactivity of the substrates dominates....... characterized the reaction path for both the hydroxylase and lyase reactions using density functional theory (DFT) calculations and the enzyme–substrate interactions by molecular dynamics (MD) simulations. Activation barriers for positions subject to hydroxylase reaction have values close to each other and span...

Rare-earth doped phosphors: oldies or goldies?

International Nuclear Information System (INIS)

Moine, B.; Bizarri, G.

2003-01-01

The scientific research on phosphors has a long history starting more than 100 years ago. But recently the appearance of new kinds of displays and lighting devices (plasma display, fluorescent lamp without mercury, etc.) induced an increase of the research of new phosphors with better luminous efficiency than those available up to now. It has been shown that the behavior of 'classical' phosphors in a plasma display panel is quite different than in a cathode ray tube and that the vacuum ultraviolet (VUV) excitation process has to be studied with care in order to improve the phosphors efficiency. That is particularly true in PDPs. It is well established now that a good phosphor for electronic or ultraviolet excitation is not necessarily a good choice for excitation in VUV. This is probably due to the fact that the excitation process is very different in that case and also because the penetration depth of the VUV photons is extremely small inducing a large contribution of the surface of the phosphor. We will illustrate this with some examples. Methods to accelerate luminous intensity decrease under VUV excitation will be described. Low efficiency, fast aging process are both drawbacks that can be solved only in the framework of fundamental studies. Quantum cutting emission may be a solution for the first one but no satisfactory process was proposed for the moment to solve the second

White-electroluminescent device with horizontally patterned blue/yellow phosphor-layer structure

International Nuclear Information System (INIS)

Won Park, Boo; Sik Choi, Nam; Won Park, Kwang; Mo Son, So; Kim, Jong Su; Kyun Shon, Pong

2007-01-01

White-electroluminescent (EL) devices with stripe-patterned and square-patterned phosphor-layer structures are fabricated through a screen printing method: electrode/BaTiO 3 insulator layer/patterned blue ZnS:Cu, Cl and yellow ZnS:Cu, Mn phosphor layer/ITO PET substrate. The luminous intensities of EL devices with stripe-patterned and square-patterned phosphor-layer structures are 33% and 23% higher than a conventional device with the phosphor-layer structure without any patterns using the phosphor blend. It can be explained in terms of the absorption of the emitted blue light of blue phosphor layer by the yellow-emitting phosphor layer. The EL device of our patterned phosphor-layer structure gives the possibility to enhance the luminance

Photoluminescence of phosphors for PDP with VUV excitation

International Nuclear Information System (INIS)

Lu, H.-C.; Chen, H.-K.; Tseng, T.-Y.; Kuo, W.-L.; Alam, M.S.; Cheng, B.-M.

2005-01-01

In a plasma display panel (PDP) He-Xe or Ne-Xe gaseous mixtures are subjected to electric discharge between two glass panels, so to generate VUV light. Red, green and blue phosphors absorb this VUV radiation and re-radiate the energy as visible light to produce the colors that appear on the screen. The phosphor plays an important role in the working of a PDP. To improve the efficiency of phosphors, we have established a photoluminescence end station coupled to the beam line of a synchrotron to study the luminescence of PDP phosphors. This luminescence is analyzed with a 0.32 m monochromator having maximum resolution 0.04 nm, and is monitored with a photomultiplier tube operated in a photon-counting mode. Preliminary data demonstrate the powerful performance of this end-station for studying PDP phosphors

Kynurenine aminotransferase III and glutamine transaminase L are identical enzymes that have cysteine S-conjugate β-lyase activity and can transaminate L-selenomethionine.

Science.gov (United States)

Pinto, John T; Krasnikov, Boris F; Alcutt, Steven; Jones, Melanie E; Dorai, Thambi; Villar, Maria T; Artigues, Antonio; Li, Jianyong; Cooper, Arthur J L

2014-11-07

Three of the four kynurenine aminotransferases (KAT I, II, and IV) that synthesize kynurenic acid, a neuromodulator, are identical to glutamine transaminase K (GTK), α-aminoadipate aminotransferase, and mitochondrial aspartate aminotransferase, respectively. GTK/KAT I and aspartate aminotransferase/KAT IV possess cysteine S-conjugate β-lyase activity. The gene for the former enzyme, GTK/KAT I, is listed in mammalian genome data banks as CCBL1 (cysteine conjugate beta-lyase 1). Also listed, despite the fact that no β-lyase activity has been assigned to the encoded protein in the genome data bank, is a CCBL2 (synonym KAT III). We show that human KAT III/CCBL2 possesses cysteine S-conjugate β-lyase activity, as does mouse KAT II. Thus, depending on the nature of the substrate, all four KATs possess cysteine S-conjugate β-lyase activity. These present studies show that KAT III and glutamine transaminase L are identical enzymes. This report also shows that KAT I, II, and III differ in their ability to transaminate methyl-L-selenocysteine (MSC) and L-selenomethionine (SM) to β-methylselenopyruvate (MSP) and α-ketomethylselenobutyrate, respectively. Previous studies have identified these seleno-α-keto acids as potent histone deacetylase inhibitors. Methylselenol (CH3SeH), also purported to have chemopreventive properties, is the γ-elimination product of SM and the β-elimination product of MSC catalyzed by cystathionine γ-lyase (γ-cystathionase). KAT I, II, and III, in part, can catalyze β-elimination reactions with MSC generating CH3SeH. Thus, the anticancer efficacy of MSC and SM will depend, in part, on the endogenous expression of various KAT enzymes and cystathionine γ-lyase present in target tissue coupled with the ability of cells to synthesize in situ either CH3SeH and/or seleno-keto acid metabolites. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

High Extraction Phosphors for Solid State Lighting

Energy Technology Data Exchange (ETDEWEB)

Summers, Chris [Phosphortech Corporation, Kennesaw, GA (United States); Menkara, Hisham [Phosphortech Corporation, Kennesaw, GA (United States); Wagner, Brent [Phosphortech Corporation, Kennesaw, GA (United States)

2011-09-01

We have developed high-index, high efficiency bulk luminescent materials and novel nano-sized phosphors for improved solid-state white LED lamps. These advances can potentially contribute to reducing the loss in luminous efficiencies due to scattering, re-absorption, and thermal quenching. The bulk and nanostructured luminescent materials investigated are index matched to GaN and have broad and size-tunable absorption bands, size and impurity tuned emission bands, size-driven elimination of scattering effects, and a separation between absorption and emission bands. These innovations were accomplished through the use of novel synthesis techniques suitable for high volume production for LED lamp applications. The program produced a full-color set of high quantum yield phosphors with high chemical stability. In the bulk phosphor study, the ZnSeS:Cu,Ag phosphor was optimized to achieve >91% efficiency using erbium (Er) and other activators as sensitizers. Detailed analysis of temperature quenching effects on a large number of ZnSeS:Cu,Ag,X and strontium- and calcium-thiogallate phosphors lead to a breakthrough in the understanding of the anti-quenching behavior and a physical bandgap model was developed of this phenomena. In a follow up to this study, optimized phosphor blends for high efficiency and color performance were developed and demonstrated a 2-component phosphor system with good white chromaticity, color temperature, and high color rendering. By extending the protocols of quantum dot synthesis, large nanocrystals, greater than 20 nm in diameter were synthesized and exhibited bulk-like behavior and blue light absorption. The optimization of ZnSe:Mn nanophosphors achieved ~85% QE The limitations of core-shell nanocrystal systems were addressed by investigating alternative deltadoped structures. To address the manufacturability of these systems, a one-pot manufacturing protocol was developed for ZnSe:Mn nanophosphors. To enhance the stability of these material

Electrolyte Additives for Phosphoric Acid Fuel Cells

DEFF Research Database (Denmark)

Gang, Xiao; Hjuler, H.A.; Olsen, C.A.

1993-01-01

, as a fuel-cell performance with the modified electrolytes. Specific conductivity measurements of some of the modified phosphoric acid electrolytes are reported. At a given temperature, the conductivity of the C4F9SO3K-modified electrolyte decreases with an increasing amount of the additive; the conductivity...... of the remains at the same value as the conductivity of the pure phosphoric acid. At a given composition, the conductivity of any modified electrolyte increases with temperature. We conclude that the improved cell performance for modified electrolytes is not due to any increase in conductivity.......Electrochemical characteristics of a series of modified phosphoric acid electrolytes containing fluorinated car on compounds and silicone fluids as additives are presented. When used in phosphoric acid fuel cells, the modified electrolytes improve the performance due to the enhanced oxygen...

A linear programming computational framework integrates phosphor-proteomics and prior knowledge to predict drug efficacy.

Science.gov (United States)

Ji, Zhiwei; Wang, Bing; Yan, Ke; Dong, Ligang; Meng, Guanmin; Shi, Lei

2017-12-21

In recent years, the integration of 'omics' technologies, high performance computation, and mathematical modeling of biological processes marks that the systems biology has started to fundamentally impact the way of approaching drug discovery. The LINCS public data warehouse provides detailed information about cell responses with various genetic and environmental stressors. It can be greatly helpful in developing new drugs and therapeutics, as well as improving the situations of lacking effective drugs, drug resistance and relapse in cancer therapies, etc. In this study, we developed a Ternary status based Integer Linear Programming (TILP) method to infer cell-specific signaling pathway network and predict compounds' treatment efficacy. The novelty of our study is that phosphor-proteomic data and prior knowledge are combined for modeling and optimizing the signaling network. To test the power of our approach, a generic pathway network was constructed for a human breast cancer cell line MCF7; and the TILP model was used to infer MCF7-specific pathways with a set of phosphor-proteomic data collected from ten representative small molecule chemical compounds (most of them were studied in breast cancer treatment). Cross-validation indicated that the MCF7-specific pathway network inferred by TILP were reliable predicting a compound's efficacy. Finally, we applied TILP to re-optimize the inferred cell-specific pathways and predict the outcomes of five small compounds (carmustine, doxorubicin, GW-8510, daunorubicin, and verapamil), which were rarely used in clinic for breast cancer. In the simulation, the proposed approach facilitates us to identify a compound's treatment efficacy qualitatively and quantitatively, and the cross validation analysis indicated good accuracy in predicting effects of five compounds. In summary, the TILP model is useful for discovering new drugs for clinic use, and also elucidating the potential mechanisms of a compound to targets.

Industrial radiography with phosphor screens

International Nuclear Information System (INIS)

Broadhead, P.

1981-01-01

An experimental system that comprises a film of low silver content and a pair of high resolution phosphor intensifying screens and a commercial industrial X-ray film of similar speed are compared for image quality. It is concluded that the use of phosphor screens offers an increase in image quality when the information is limited by the graininess or quantum mottle of a radiograph which is frequently the case in practical radiography. (author)

Estimating environmental co-benefits of U.S. low-carbon pathways using the GCAM-USA integrated assessment model

Data.gov (United States)

U.S. Environmental Protection Agency — There are many technological pathways that can lead to reduced carbon dioxide (CO2) emissions. However, these pathways can have substantially different impacts on...

Remoção de chumbo(II em sistemas descontínuos por carvões ativados com ácido fosfórico e com vapor Lead(II removal in discontinous systems by carbon activated by phosphoric acid and vapor

Directory of Open Access Journals (Sweden)

Cristiane Imenes de Campos Bueno

2007-01-01

Full Text Available Adsorption of heavy metal cations by activated carbon is dependent on the capacity of the material in promoting adsorption and the time needed to reach equilibrium. Carbon samples were previously activated either by phosphoric acid treatment at 400 ºC or by steam at 800 ºC. The results of Pb(II adsorption by these activated carbons have shown that equilibrium was typically reached within the first 5 min of contact between carbon and metal solution, with a maximum adsorption capacity higher than 69 mg g-1 for the vapor-activated sample. Temperature influences the sorption capacity, which corresponds to an endothermic process. Lead(II retention is more pronounced at high temperature and low pH.

Phosphate phosphors for solid-state lighting

Energy Technology Data Exchange (ETDEWEB)

Shinde, Kartik N. [N.S. Science and Arts College, Bhadrawati (India). Dept. of Physics; Swart, H.C. [University of the Orange Free State, Bloemfontein (South Africa). Dept. of Physics; Dhoble, S.J. [R.T.M. Nagpur Univ. (India). Dept. of Physics; Park, Kyeongsoon [Sejong Univ., Seoul (Korea, Republic of). Faculty of Nanotechnology and Advanced Materials Engineering

2012-07-01

Essential information for students in researchers working towards new and more efficient solid-state lighting. Comprehensive survey based on the authors' long experience. Useful both for teaching and reference. The idea for this book arose out of the realization that, although excellent surveys and a phosphor handbook are available, there is no single source covering the area of phosphate based phosphors especially for lamp industry. Moreover, as this field gets only limited attention in most general books on luminescence, there is a clear need for a book in which attention is specifically directed toward this rapidly growing field of solid state lighting and its many applications. This book is aimed at providing a sound introduction to the synthesis and optical characterization of phosphate phosphor for undergraduate and graduate students as well as teachers and researchers. The book provides guidance through the multidisciplinary field of solid state lighting specially phosphate phosphors for beginners, scientists and engineers from universities, research organizations, and especially industry. In order to make it useful for a wide audience, both fundamentals and applications are discussed, together.

A SrBPO5: Eu2+ phosphor for neutron imaging

International Nuclear Information System (INIS)

Sakasai, K.; Katagiri, M.; Toh, K.; Nakamura, T.

2001-01-01

A SrBPO 5 : Eu 2+ phosphor material has been investigated for neutron imaging. This phosphor showed photostimulated luminescence (PSL) by illumination of 635 nm laser light after X-ray irradiation. The spectral characteristics of the phosphor were similar to those of BaFBr: Eu 2+ , which is a commonly used phosphor of imaging plates. In addition, we found that this phosphor also showed PSL for neutron irradiation. It comes from the fact that it contains atomic boron in base matrix. Therefore, this phosphor can be used for neutron imaging without adding neutron sensitive materials such as Gd in commercially available neutron imaging plates. The PSL intensity and the neutron detection will be increased by using enriched boron instead of natural boron. (author)

AlgM4: A New Salt-Activated Alginate Lyase of the PL7 Family with Endolytic Activity

Directory of Open Access Journals (Sweden)

Guiyuan Huang

2018-04-01

Full Text Available Alginate lyases are a group of enzymes that catalyze the depolymerization of alginates into oligosaccharides or monosaccharides. These enzymes have been widely used for a variety of purposes, such as producing bioactive oligosaccharides, controlling the rheological properties of polysaccharides, and performing structural analyses of polysaccharides. The algM4 gene of the marine bacterium Vibrio weizhoudaoensis M0101 encodes an alginate lyase that belongs to the polysaccharide lyase family 7 (PL7. In this study, the kinetic constants Vmax (maximum reaction rate and Km (Michaelis constant of AlgM4 activity were determined as 2.75 nmol/s and 2.72 mg/mL, respectively. The optimum temperature for AlgM4 activity was 30 °C, and at 70 °C, AlgM4 activity dropped to 11% of the maximum observed activity. The optimum pH for AlgM4 activity was 8.5, and AlgM4 was completely inactive at pH 11. The addition of 1 mol/L NaCl resulted in a more than sevenfold increase in the relative activity of AlgM4. The secondary structure of AlgM4 was altered in the presence of NaCl, which caused the α-helical content to decrease from 12.4 to 10.8% and the β-sheet content to decrease by 1.7%. In addition, NaCl enhanced the thermal stability of AlgM4 and increased the midpoint of thermal denaturation (Tm by 4.9 °C. AlgM4 exhibited an ability to degrade sodium alginate, poly-mannuronic acid (polyM, and poly-guluronic acid (polyG, resulting in the production of oligosaccharides with a degree of polymerization (DP of 2–9. AlgM4 possessed broader substrate, indicating that it is a bifunctional alginate lyase. Thus, AlgM4 is a novel salt-activated and bifunctional alginate lyase of the PL7 family with endolytic activity.

Probing Reversible Chemistry in Coenzyme B12-Dependent Ethanolamine Ammonia Lyase with Kinetic Isotope Effects

Science.gov (United States)

Jones, Alex R; Rentergent, Julius; Scrutton, Nigel S; Hay, Sam

2015-01-01

Coenzyme B12-dependent enzymes such as ethanolamine ammonia lyase have remarkable catalytic power and some unique properties that enable detailed analysis of the reaction chemistry and associated dynamics. By selectively deuterating the substrate (ethanolamine) and/or the β-carbon of the 5′-deoxyadenosyl moiety of the intrinsic coenzyme B12, it was possible to experimentally probe both the forward and reverse hydrogen atom transfers between the 5′-deoxyadenosyl radical and substrate during single-turnover stopped-flow measurements. These data are interpreted within the context of a kinetic model where the 5′-deoxyadenosyl radical intermediate may be quasi-stable and rearrangement of the substrate radical is essentially irreversible. Global fitting of these data allows estimation of the intrinsic rate constants associated with CoC homolysis and initial H-abstraction steps. In contrast to previous stopped-flow studies, the apparent kinetic isotope effects are found to be relatively small. PMID:25950663

Encapsulation of strontium aluminate phosphors to enhance water resistance and luminescence

International Nuclear Information System (INIS)

Zhu Yong; Zeng Jianghua; Li Wenyu; Xu Li; Guan Qiu; Liu Yingliang

2009-01-01

Strontium aluminate SrAl 2 O 4 :Eu 2+ ,Dy 3+ phosphors are chemically unstable against water or even moisture. To enhance the water resistance of the phosphors, an encapsulation was performed by direct surface reactions with phosphoric acid (H 3 PO 4 ). The morphology, surface structure, surface element composition, water resistance, luminescence, and photoacoustic spectrum of the phosphors before and after encapsulation were discussed. Experimental results showed that phosphors were perfectly encapsulated by amorphous layers in nanoscale and crystalline layers in microscale under different conditions. The water resistance of phosphors was greatly enhanced by the two types of layer. More importantly, the amorphous layers enhanced the luminescence of phosphors markedly. The possible mechanism for the enhancements was also proposed.

Photocatalytic effects for the TiO2-coated phosphor materials

International Nuclear Information System (INIS)

Yoon, Jin-Ho; Jung, Sang-Chul; Kim, Jung-Sik

2011-01-01

Research highlights: → The photocatalytic behavior of the coupling of TiO 2 with phosphorescent materials. → The photobleaching of an MB aqueous solution under visible light irradiation. → The ALD TiO 2 -coated phosphor composite showed much higher photocatalytic reactivity. → The light emitted from the phosphors contributed to the photo-generation. - Abstract: This study investigated the photocatalytic behavior of the coupling of TiO 2 with phosphorescent materials. A TiO 2 thin film was deposited on CaAl 2 O 4 :Eu 2+ ,Nd 3+ phosphor particles by using atomic layer deposition (ALD), and its photocatalytic reaction was investigated by the photobleaching of an aqueous solution of methylene-blue (MB) under visible light irradiation. To clarify the mechanism of the TiO 2 -phosphorescent materials, two different samples of TiO 2 -coated phosphor and TiO 2 -Al 2 O 3 -coated phosphor particles were prepared. The photocatalytic mechanisms of the ALD TiO 2 -coated phosphor powders were different from those of the pure TiO 2 and TiO 2 -Al 2 O 3 -coated phosphor. The absorbance in a solution of the ALD TiO 2 -coated phosphor decreased much faster than that of pure TiO 2 under visible irradiation. In addition, the ALD TiO 2 -coated phosphor showed moderately higher photocatalytic degradation of MB solution than the TiO 2 -Al 2 O 3 -coated phosphor did. The TiO 2 -coated phosphorescent materials were characterized by transmission electron microscopy (TEM), Auger electron spectroscopy (AES) and X-ray photon spectroscopy (XPS).

Nitrogen and phosphorous limitation reduces the effects of land use change on land carbon uptake or emission

International Nuclear Information System (INIS)

Wang, Ying-Ping; Zhang, Qian; Dai, Yongjiu; Pitman, Andrew J

2015-01-01

We used an Earth System Model that includes both nitrogen (N) and phosphorus (P) cycling to simulate the impacts of land-use and land-cover change (LULCC) for two representative concentration pathways (RCPs): a reforestation scenario (RCP4.5) and a deforestation scenario (RCP8.5). For each RCP, we performed simulations with and without LULCC using the carbon (C only) mode or including the full C, N and P cycles (CNP). We show, for the first time, that inclusion of N and P cycling reduces both the carbon uptake from reforestation in RCP4.5 and the carbon emission from deforestation in RCP8.5. Specifically, carbon-nutrient interaction reduces carbon uptake in RCP4.5 from 55 Pg C (C only) to 21 Pg C (CNP), or the emissions in RCP8.5 from 72 Pg C (C only) to 56 Pg C (CNP). Most of those reductions result from much weaker responses of net primary production to CO 2 fertilization and climate change when carbon-nutrient interaction is taken into account, as compared to C only simulations. Our results highlight the importance of including nutrient-carbon interaction in estimating the carbon benefit from reforestation and carbon loss from deforestation in a future world with higher CO 2 and a warmer climate. Because of the stronger nutrient limitation, carbon gain from reforestation in the temperate and boreal regions is much less than the carbon loss from deforestation in the subtropical and tropical regions from 2006 to 2100 for the two RCPs. Therefore protecting the existing subtropical and tropical forests is about twice as effective as planting new forests in the temperate and boreal regions for climate mitigation. (letter)

Investigation of the synergic effect of some neutral organophosphoric compounds on the extraction of uranium from phosphoric acid solutions by D1-(2-Ethyl Hexyl) phosphoric acid

International Nuclear Information System (INIS)

Stas, J.; Khorfan, S.; Koudsi, Y.

1998-05-01

The extraction of uranium (VI) from pure phosphoric acid media by D2EHPA/Kerosene has been studied. The mechanism of the extraction was found as follows: The logarithm of the equilibrium constant of the extraction (LogKex) was found (3.06), (3.32), (3.24), (3.3) for the following phosphoric acid concentrations respectively (1), (2), (3), (4) Mol/1, and the enthalpy change DELTA H was found (-100.68 kj/mol). (-76 kj/mol) for (1), (2) mol/1 phosphoric acid concentrations. The synergic effect of TOPO, TBP, and TBPI with DEHPA have been studied during the extraction of uranium from pure phosphoric acid and Syrian commercial phosphoric acid. The synergic effect increases as follows: TBP< TBPI<< TOPO (In pure phosphoric acid), TBPI approx TBP<< TOPO (In Syrian commercial phosphoric acid). The difficulty of extracting uranium (VI) from Syrian commercial phosphoric acid in comparison with pure phosphoric acid is due to the presence of several impurities capable of complexing uranium, and a small amounts of solid and organic matters, all these are factors which reduce the distribution coefficient of uranium. (Author)

A survey of phosphors novel for thermography

Energy Technology Data Exchange (ETDEWEB)

Bruebach, J., E-mail: bruebach@ekt.tu-darmstadt.d [Fachgebiet Reaktive Stroemungen und Messtechnik, Center of Smart Interfaces Technische Universitaet Darmstadt, Petersenstrasse 32, 64287 Darmstadt (Germany); Kissel, T. [Fachgebiet Reaktive Stroemungen und Messtechnik, Center of Smart Interfaces Technische Universitaet Darmstadt, Petersenstrasse 32, 64287 Darmstadt (Germany); Frotscher, M. [Eduard-Zintl-Institut fuer Anorganische und Physikalische Chemie, Technische Universitaet Darmstadt, Petersenstrasse 18, 64287 Darmstadt (Germany); Euler, M. [Fachgebiet Reaktive Stroemungen und Messtechnik, Center of Smart Interfaces Technische Universitaet Darmstadt, Petersenstrasse 32, 64287 Darmstadt (Germany); Albert, B. [Eduard-Zintl-Institut fuer Anorganische und Physikalische Chemie, Technische Universitaet Darmstadt, Petersenstrasse 18, 64287 Darmstadt (Germany); Dreizler, A. [Fachgebiet Reaktive Stroemungen und Messtechnik, Center of Smart Interfaces Technische Universitaet Darmstadt, Petersenstrasse 32, 64287 Darmstadt (Germany)

2011-04-15

With regard to phosphor thermometry, seven luminescent ceramic materials were synthesised and characterised, namely CaMoO{sub 4}:Eu{sup 3+}, CaTiO{sub 3}:Pr{sup 3+}, LaPO{sub 4}:Eu{sup 3+}, LaVO{sub 4}:Eu{sup 3+}, LiAl{sub 5}O{sub 8}:Fe{sup 3+}, TiMg{sub 2}O{sub 4}:Mn{sup 4+} and ZnGa{sub 2}O{sub 4}:Mn{sup 2+}. In this context, emission spectra and temperature lifetime characteristics are presented. Thus, a survey of phosphors novel for thermography is given in order to encourage further studies and more detailed characterisations of the respective materials. - Research Highlights: Seven phosphor materials novel for thermometry were synthesised. These materials were characterised diffractometrically as well as concerning their emission spectra and lifetime temperature characteristics. The number of phosphor materials characterised for thermometry purposes was extended by seven materials.

Characteristics of the Panasonic UD-802 phosphors

International Nuclear Information System (INIS)

Ben-Shachar, B.; Catchen, G.L.; Hoffman, J.M.

1989-01-01

Several basic dosimetric characteristics of Li 2 B 4 O 7 :Cu and CaSO 4 :Tm phosphors in Panasonic UD-802 dosemeters were measured. The TL dose response linearity was determined over the useful range of personnel and environmental dosimetry (0.005 - 10 mGy), and the minimum measurable doses were calculated. The intrinsic ultraviolet (UV) radiation sensitivity of both phosphors was checked before and after γ irradiation for the purpose of re-assessing high doses. The results indicate that Li 2 B 4 O 7 :Cu is UV sensitive and, therefore, re-assessment is not applicable. Although the CaSO 4 :Tm phosphor exhibited UV sensitivity after γ irradiation, the results were not consistent with those reported earlier and more study is required. The fading of both phosphors was evaluated in Panasonic UD-801 dosemeters for periods up to 90 days. (author)

Improvements in phosphors

International Nuclear Information System (INIS)

Rabatin, J.G.

1981-01-01

For X-ray image converter applications, especially when used in medical radiography, it is desirable to improve the speed and brightness of response for conversion of X-rays in phosphors. The rare earth oxyhalide phosphors coactivated with a combination of rare earth activators described in this patent are capable of exhibiting low afterglow with high ultraviolet emission. They have the general formula Lnsub(1-y-w)OX:Tbsub(y)Tmsub(w) where Ln is lanthanum or gadolinium, X is chlorine and/or bromine, y is from 0.0005 to 0.010 moles per mole and w is from 0.00005 to 0.005 moles per mole of the Lnsub(1-y-w)OX host. The method of preparation and characteristics of speed, afterglow and UV emission are described. (U.K.)

Carbon metabolic pathways in phototrophic bacteria and their broader evolutionary implications

Directory of Open Access Journals (Sweden)

Kuo-Hsiang eTang

2011-08-01

Full Text Available Photosynthesis is the biological process that converts solar energy to biomass, bio-products and biofuel. It is the only major natural solar energy storage mechanism on Earth. To satisfy the increased demand for sustainable energy sources and identify the mechanism of photosynthetic carbon assimilation, which is one of the bottlenecks in photosynthesis, it is essential to understand the process of solar energy storage and associated carbon metabolism in photosynthetic organisms. Researchers have employed physiological studies, microbiological chemistry, enzyme assays, genome sequencing, transcriptomics, and 13C-based metabolomics/fluxomics to investigate central carbon metabolism and enzymes that operate in phototrophs. In this report, we review diverse CO2 assimilation pathways, acetate assimilation, carbohydrate catabolism, the TCA cycle and some key and/or unconventional enzymes in central carbon metabolism of phototrophic microorganisms. We also discuss the reducing equivalent flow during photoautotrophic and photoheterotrophic growth, evolutionary links in the central carbon metabolic network, and correlations between photosynthetic and non-photosynthetic organisms. Considering the metabolic versatility in these fascinating and diverse photosynthetic bacteria, many essential questions in their central carbon metabolism still remain to be addressed.

Angle-resolved photoluminescence spectrum of a uniform phosphor layer

Science.gov (United States)

Fujieda, Ichiro; Ohta, Masamichi

2017-10-01

A photoluminescence spectrum depends on an emission angle due to self-absorption in a phosphor material. Assuming isotropic initial emission and Lambert-Beer's law, we have derived simple expressions for the angle-resolved spectra emerging from the top and bottom surfaces of a uniform phosphor layer. The transmittance of an excitation light through the phosphor layer can be regarded as a design parameter. For a strongly-absorbing phosphor layer, the forward flux is less intense and more red-shifted than the backward flux. The red-shift is enhanced as the emission direction deviates away from the plane normal. When we increase the transmittance, the backward flux decreases monotonically. The forward flux peaks at a certain transmittance value. The two fluxes become similar to each other for a weakly-absorbing phosphor layer. We have observed these behaviors in experiment. In a practical application, self-absorption decreases the efficiency of conversion and results in angle-dependent variations in chromaticity coordinates. A patterned phosphor layer with a secondary optical element such as a remote reflector alleviates these problems.

17beta-estradiol promotes the odonto/osteogenic differentiation of stem cells from apical papilla via mitogen-activated protein kinase pathway.

Science.gov (United States)

Li, Yao; Yan, Ming; Wang, Zilu; Zheng, Yangyu; Li, Junjun; Ma, Shu; Liu, Genxia; Yu, Jinhua

2014-11-17

Estrogen plays an important role in the osteogenic differentiation of mesenchymal stem cells, while stem cells from apical papilla (SCAP) can contribute to the formation of dentin/bone-like tissues. To date, the effects of estrogen on the differentiation of SCAP remain unclear. SCAP was isolated and treated with 10⁻⁷ M 17beta-estradiol (E2). The odonto/osteogenic potency and the involvement of mitogen-activated protein kinase (MAPK) signaling pathway were subsequently investigated by using methyl-thiazolyl-tetrazolium (MTT) assay, and other methods. MTT and flow cytometry results demonstrated that E2 treatment had no effect on the proliferation of SCAP in vitro, while alkaline phosphatase (ALP) assay and alizarin red staining showed that E2 can significantly promote ALP activity and mineralization ability in SCAP. Real-time reverse transcription polymerase chain reaction (RT-PCR) and western blot assay revealed that the odonto/osteogenic markers (ALP, DMP1/DMP1, DSPP/DSP, RUNX2/RUNX2, OSX/OSX and OCN/OCN) were significantly upregulated in E2-treated SCAP. In addition, the expression of phosphor-p38 and phosphor-JNK in these stem cells was enhanced by E2 treatment, as was the expression of the nuclear downstream transcription factors including phosphor-Sp1, phosphor-Elk-1, phosphor-c-Jun and phosphor-c-Fos, indicating the activation of MAPK signaling pathway during the odonto/osteogenic differentiation of E2-treated SCAP. Conversely, the differentiation of E2-treated SCAP was inhibited in the presence of MAPK specific inhibitors. The ondonto/osteogenic differentiation of SCAP is enhanced by 10⁻⁷ M 17beta-estradiol via the activation of MAPK signaling pathway.

The 3-hydroxy-2-butanone pathway is required for Pectobacterium carotovorum pathogenesis.

Directory of Open Access Journals (Sweden)

Maria del Pilar Marquez-Villavicencio

Full Text Available Pectobacterium species are necrotrophic bacterial pathogens that cause soft rot diseases in potatoes and several other crops worldwide. Gene expression data identified Pectobacterium carotovorum subsp. carotovorum budB, which encodes the α-acetolactate synthase enzyme in the 2,3-butanediol pathway, as more highly expressed in potato tubers than potato stems. This pathway is of interest because volatiles produced by the 2,3-butanediol pathway have been shown to act as plant growth promoting molecules, insect attractants, and, in other bacterial species, affect virulence and fitness. Disruption of the 2,3-butanediol pathway reduced virulence of P. c. subsp. carotovorum WPP14 on potato tubers and impaired alkalinization of growth medium and potato tubers under anaerobic conditions. Alkalinization of the milieu via this pathway may aid in plant cell maceration since Pectobacterium pectate lyases are most active at alkaline pH.

Investigation of saturation effects in ceramic phosphors for laser lighting

DEFF Research Database (Denmark)

Krasnoshchoka, Anastasiia; Thorseth, Anders; Dam-Hansen, Carsten

2017-01-01

We report observation of saturation effects in a Ce:LuAG and Eu-doped nitride ceramic phosphor for conversion of blue laser light for white light generation. The luminous flux from the phosphors material increases linearly with the input power until saturation effects limit the conversion....... It is shown, that the temperature of the phosphor layer influences the saturation power level and the conversion efficiency. It is also shown that the correlated color temperature (CCT), phosphor conversion efficiency and color rendering index (CRI) are dependent both on incident power and spot size diameter...... of the illumination. A phosphor conversion efficiency up to 140.8 lm/W with CRI of 89.4 was achieved. The saturation in a ceramic phosphor, when illuminated by high intensity laser diodes, is estimated to play the main role in limiting the available luminance from laser based lighting systems....

A Novel Bifunctional Amino Acid Racemase With Multiple Substrate Specificity, MalY From Lactobacillus sakei LT-13: Genome-Based Identification and Enzymological Characterization

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Shiro Kato

2018-03-01

Full Text Available The Lactobacillus sakei strain LK-145 isolated from Moto, a starter of sake, produces potentially large amounts of three D-amino acids, D-Ala, D-Glu, and D-Asp, in a medium containing amylase-digested rice as a carbon source. The comparison of metabolic pathways deduced from the complete genome sequence of strain LK-145 to the type culture strain of Lactobacillus sakei strain LT-13 showed that the L- and D-amino acid metabolic pathways are similar between the two strains. However, a marked difference was observed in the putative cysteine/methionine metabolic pathways of strain LK-145 and LT-13. The cystathionine β-lyase homolog gene malY was annotated only in the genome of strain LT-13. Cystathionine β-lyase is an important enzyme in the cysteine/methionine metabolic pathway that catalyzes the conversion of L-cystathionine into L-homocysteine. In addition to malY, most genome-sequenced strains of L. sakei including LT-13 lacked the homologous genes encoding other putative enzymes in this pathway. Accordingly, the cysteine/methionine metabolic pathway likely does not function well in almost all strains of L. sakei. We succeeded in cloning and expressing the malY gene from strain LT-13 (Ls-malY in the cells of Escherichia coli BL21 (DE3 and characterized the enzymological properties of Ls-MalY. Spectral analysis of purified Ls-MalY showed that Ls-MalY contained a pyridoxal 5′-phosphate (PLP as a cofactor, and this observation agreed well with the prediction based on its primary structure. Ls-MalY showed amino acid racemase activity and cystathionine β-lyase activity. Ls-MalY showed amino acid racemase activities in various amino acids, such as Ala, Arg, Asn, Glu, Gln, His, Leu, Lys, Met, Ser, Thr, Trp, and Val. Mutational analysis revealed that the -amino group of Lys233 in the primary structure of Ls-MalY likely bound to PLP, and Lys233 was an essential residue for Ls-MalY to catalyze both the amino acid racemase and β-lyase reactions. In

Biocatalytic Enantioselective Synthesis of N-Substituted Aspartic Acids by Aspartate Ammonia Lyase

NARCIS (Netherlands)

Weiner, Barbara; Poelarends, Gerrit J.; Janssen, Dick B.; Feringa, Ben L.

2008-01-01

The gene encoding aspartate ammonia lyase (aspB) from Bacillus sp. YM55-1 has been cloned and overexpressed, and the recombinant enzyme containing a C-terminal His6 tag has been purified to homogeneity and subjected to kinetic characterization. Kinetic studies have shown that the His6 tag does not

Laser discrimination by stimulated emission of a phosphor

Science.gov (United States)

Mathur, V. K.; Chakrabarti, K.

1991-01-01

A method for discriminating sources of UV, near infrared, and far infrared laser radiation was discovered. This technology is based on the use of a single magnesium sulfide phosphor doubly doped with rare earth ions, which is thermally/optically stimulated to generate colors correlatable to the incident laser radiation. The phosphor, after initial charging by visible light, exhibits green stimulated luminescence when exposed to a near infrared source (Nd: YAG laser). On exposure to far infrared sources (CO2 laser) the phosphor emission changes to orange color. A UV laser produces both an orange red as well as green color. A device using this phosphor is useful for detecting the laser and for discriminating between the near infrared, far infrared, and UV lasers. The technology is also capable of infrared laser diode beam profiling since the radiation source leaves an imprint on the phosphor that can be photographed. Continued development of the technology offers potential for discrimination between even smaller bandwidths within the infrared spectrum, a possible aid to communication or wavemixing devices that need to rapidly identify and process optical signals.

Synthesis and characterization of chemically activated carbon derived from arecanut shell

Directory of Open Access Journals (Sweden)

A. S. Jadhav

2016-03-01

Full Text Available Activated carbon (AC was prepared from areca-nut shell (AS by chemical activation using phosphoric acid (PA. Activated carbon was prepared in three batches using phosphoric acid of 50 gm, 100 gm, and 300 gm with varying impregnation ratios by weight of 1:1, 2:1 and 3:1, 4:1 each. Characterization of the prepared activated carbon was done by methylene blue number (MBN, iodine number (IN, acid adsorption test (AAT, and elemental composition. Activation was carried out at 400 C. It was found that activated carbon derived from areca-nut shell shown improved results for methylene blue number (MBN, iodine number (IN, and acid adsorption test(AAT. Thermal analysis was carried out to know the weight loss and SEM was performed to know the morphology of AC.

The replicative DNA polymerase of herpes simplex virus 1 exhibits apurinic/apyrimidinic and 5′-deoxyribose phosphate lyase activities

Science.gov (United States)

Bogani, Federica; Boehmer, Paul E.

2008-01-01

Base excision repair (BER) is essential for maintaining genome stability both to counter the accumulation of unusual bases and to protect from base loss in the DNA. Herpes simplex virus 1 (HSV-1) is a large dsDNA virus that encodes its own DNA replication machinery, including enzymes involved in nucleotide metabolism. We report on a replicative family B and a herpesvirus-encoded DNA Pol that possesses DNA lyase activity. We have discovered that the catalytic subunit of the HSV-1 DNA polymerase (Pol) (UL30) exhibits apurinic/apyrimidinic (AP) and 5′-deoxyribose phosphate (dRP) lyase activities. These activities are integral to BER and lead to DNA cleavage on the 3′ side of abasic sites and 5′-dRP residues that remain after cleavage by 5′-AP endonuclease. The UL30-catalyzed reaction occurs independently of divalent cation and proceeds via a Schiff base intermediate, indicating that it occurs via a lyase mechanism. Partial proteolysis of the Schiff base shows that the DNA lyase activity resides in the Pol domain of UL30. These observations together with the presence of a virus-encoded uracil DNA glycosylase indicates that HSV-1 has the capacity to perform critical steps in BER. These findings have implications on the role of BER in viral genome maintenance during lytic replication and reactivation from latency. PMID:18695225

Carbon nanopipettes characterize calcium release pathways in breast cancer cells

Energy Technology Data Exchange (ETDEWEB)

Schrlau, Michael G [Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, PA 19104 (United States); Brailoiu, Eugen; Dun, Nae J [Department of Pharmacology, Temple University, Philadelphia, PA 19104 (United States); Patel, Sandip [Department of Physiology, University College London, London WC1E 6BT (United Kingdom); Gogotsi, Yury [Department of Materials Science and Engineering, Drexel University, Philadelphia, PA 19104 (United States); Bau, Haim H [Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, 229 Towne Building, 220 S. 33rd Street, Philadelphia, PA 19104 (United States)], E-mail: mschrlau@seas.upenn.edu, E-mail: ebrailou@temple.edu, E-mail: patel.s@ucl.ac.uk, E-mail: yg36@drexel.edu, E-mail: ndun@temple.edu, E-mail: bau@seas.upenn.edu

2008-08-13

Carbon-based nanoprobes are attractive for minimally invasive cell interrogation but their application in cell physiology has thus far been limited. We have developed carbon nanopipettes (CNPs) with nanoscopic tips and used them to inject calcium-mobilizing messengers into cells without compromising cell viability. We identify pathways sensitive to cyclic adenosine diphosphate ribose (cADPr) and nicotinic acid adenine dinucleotide phosphate (NAADP) in breast carcinoma cells. Our findings demonstrate the superior utility of CNPs for intracellular delivery of impermeant molecules and, more generally, for cell physiology studies. The CNPs do not appear to cause any lasting damage to cells. Their advantages over commonly used glass pipettes include smaller size, breakage and clogging resistance, and potential for multifunctionality such as in concurrent injection and electrical measurements.

Carbon nanopipettes characterize calcium release pathways in breast cancer cells

International Nuclear Information System (INIS)

Schrlau, Michael G; Brailoiu, Eugen; Dun, Nae J; Patel, Sandip; Gogotsi, Yury; Bau, Haim H

2008-01-01

Carbon-based nanoprobes are attractive for minimally invasive cell interrogation but their application in cell physiology has thus far been limited. We have developed carbon nanopipettes (CNPs) with nanoscopic tips and used them to inject calcium-mobilizing messengers into cells without compromising cell viability. We identify pathways sensitive to cyclic adenosine diphosphate ribose (cADPr) and nicotinic acid adenine dinucleotide phosphate (NAADP) in breast carcinoma cells. Our findings demonstrate the superior utility of CNPs for intracellular delivery of impermeant molecules and, more generally, for cell physiology studies. The CNPs do not appear to cause any lasting damage to cells. Their advantages over commonly used glass pipettes include smaller size, breakage and clogging resistance, and potential for multifunctionality such as in concurrent injection and electrical measurements

Removal of imidacloprid using activated carbon produced from ...

African Journals Online (AJOL)

In this study, Ricinodendron heudelotii (akpi) shells are used as precursor to prepare activated carbon via chemical activation using phosphoric acid. The characterization of the obtained activated carbon is performed using X-ray diffraction (XRD), Boehm titration method and adsorption of acetic acid. The results show that ...

Refeeding syndrome in a young woman with argininosuccinate lyase deficiency.

Science.gov (United States)

Stuy, M; Chen, G-F; Masonek, J M; Scharschmidt, B F

2015-09-01

A severely chronically protein and calorie restricted young woman with argininosuccinate lyase deficiency developed transient refeeding syndrome (RFS) and hyperammonemia after modest diet liberalization following initiation of glycerol phenylbutyrate (GPB). The patient required IV supportive care and supplementation with potassium, magnesium and calcium. She is now doing well on GPB and an appropriate maintenance diet. Susceptibility to RFS should be considered in chronically nutritionally restricted patients with metabolic disorders after liberalization of diet.

Refeeding syndrome in a young woman with argininosuccinate lyase deficiency☆

Science.gov (United States)

Stuy, M.; Chen, G.-F.; Masonek, J.M.; Scharschmidt, B.F.

2015-01-01

A severely chronically protein and calorie restricted young woman with argininosuccinate lyase deficiency developed transient refeeding syndrome (RFS) and hyperammonemia after modest diet liberalization following initiation of glycerol phenylbutyrate (GPB). The patient required IV supportive care and supplementation with potassium, magnesium and calcium. She is now doing well on GPB and an appropriate maintenance diet. Susceptibility to RFS should be considered in chronically nutritionally restricted patients with metabolic disorders after liberalization of diet. PMID:26937403

Synthesis and photoluminescence properties of Eu{sup 3+}, Sm{sup 3+} and Pr{sup 3+} doped Ca{sub 2}ZnWO{sub 6} phosphors for phosphor converted LED

Energy Technology Data Exchange (ETDEWEB)

Dabre, K.V. [Department of Physics, Arts, Commerce and Science College, Koradi, Nagpur-441111, Maharashtra (India); Dhoble, S.J., E-mail: sjdhoble@rediffmail.com [Department of Physics, R.T.M. Nagpur University, Nagpur-440033, Maharashtra (India)

2014-06-01

In this work, we report on the synthesis and photoluminescence (PL) properties of rare earth (Eu{sup 3+}, Sm{sup 3+} and Pr{sup 3+}) doped double perovskite tungstate Ca{sub 2}ZnWO{sub 6} phosphor. The phosphors were synthesized by two step modified solid state method. Phase purity and formation of phosphor were confirmed by XRD technique. PL spectra of Eu{sup 3+}, Sm{sup 3+} and Pr{sup 3+} doped phosphor show intense emission peaks in red region at 615, 604 and 650 nm respectively, upon the visible excitation of 466 nm (Eu{sup 3+}), 410 nm (Sm{sup 3+}) and 491 nm (Pr{sup 3+}). The CIE coordinates of the phosphors are in the yellow (Sm{sup 3+} doped sample) and orange (Eu{sup 3+} and Pr{sup 3+} doped sample) regions near the edge of color space which confirms their applicability in LEDs. -- Highlights: •Eu{sup 3+}, Sm{sup 3+} and Pr{sup 3+} doped and undoped samples of Ca{sub 2}ZnWO{sub 6} phosphor synthesized by Solid state method. •The phosphors have intense excitation in violet and blue region of visible spectrum. •Phosphors show intense emission peaks in red region. •CIE coordinates of phosphors are lie in yellow (Sm{sup 3+} doped phosphor) and orange (Eu{sup 3+} and Pr{sup 3+} doped phosphor) region near to edge of color space.

Synthesis and luminescent properties of CaCO3:Eu3+@SiO2 phosphors with core-shell structure

Science.gov (United States)

Liu, Min; Kang, Ming; Chen, Kexu; Mou, Yongren; Sun, Rong

2018-03-01

Integrating the processes of preparation of CaCO3:Eu3+ and its surface-coating, core-shell structured CaCO3:Eu3+@SiO2 phosphors with red emission were synthesized by the carbonation method and surface precipitation procedure using sodium silicate as silica source. The phase structure, thermal stability, morphology and luminescent property of the as-synthesized samples were characterized by X-ray diffraction, Fourier transform infrared spectrum, thermal analysis, field-emission scanning electron microscopy, transmission electron microscope and photoluminescence spectra. The experimental results show that Eu3+ ions as the luminescence center are divided into two types: one is at the surface of the CaCO3 and the other inhabits the site of Ca2+. For CaCO3:Eu3+@SiO2 phosphors, the SiO2 layers are continuously coated on the surface of CaCO3:Eu3+ and show a typical core-shell structure. After coated with SiO2 layer, the luminous intensity and the compatibility with the rubber matrix increase greatly. Additionally, the luminous intensity increases with the increasing of Eu3+ ions concentration in CaCO3 core and concentration quenching occurs when Eu3+ ions concentration exceeds 7.0 mol%, while it is 5.0 mol% for CaCO3:Eu3+ phosphors. Therefore, preparation of CaCO3:Eu3+@SiO2 phosphors can not only simplify the experimental process through integrating the preparation of CaCO3:Eu3+ and SiO2 layer, but also effectively increase the luminous intensities of CaCO3:Eu3+ phosphors. The as-obtained phosphors may have potential applications in the fields of optical materials and functional polymer composite materials, such as plastics and rubbers.

Two pectin lyase genes, pnl-1 and pnl-2, from Colletotrichum gloeosporioides f. sp. malvae differ in a cellulose-binding domain and in their expression during infection of Malva pusilla.

Science.gov (United States)

Wei, Yangdou; Shih, Jenny; Li, Jieran; Goodwin, Paul H

2002-07-01

Two pectin lyase genes, designated pnl-1 and pnl-2, were cloned from Colletotrichum gloeosporioides f. sp. malvae, a pathogen of round-leaved mallow (Malva pusilla). pnl-1 was isolated using cDNA from infected plant material; pnl-2 was isolated using cDNA from 3-day-old mycelia grown in mallow-cell-wall extract (MCWE) broth. pnl-1 is the first pectinase gene described thus far to encode a cellulose-binding domain (CBD), which is common in cellulases and xylanases, whereas pnl-2 encodes a pectin lyase that lacks a CBD. In pure culture, pnl-1 expression could be detected when purified pectin or glucose was the sole carbon source, but not when MCWE was the sole carbon source. The lack of pnl-1 expression appeared to be due to gene repression by some unknown factor(s) in the cell-wall extract. In contrast, expression of pnl-2 was detected in cultures when MCWE, but not when purified pectin or glucose, was the sole carbon source. In infected tissue, detection of pnl-1 expression by Northern-blot hybridization and by RT-PCR began with the onset of the necrotrophic phase of infection. Expression ofpnl-2 was not detectable by Northern-blot hybridization, but was observed byRT-PCR in both the biotrophic and necrotrophic phases of infection. The differences between pnl-1 and pnl-2 (i.e. pnl-1 encoding a CBD and differences in the expression patterns of both genes) may be related to the requirements of C. gloeosporioides f. sp. malvae to be able to grow in host tissue under the different conditions present during the biotrophic and necrotrophic phases of infection.

Structural and Biochemical Characterization of a Copper-Binding Mutant of the Organomercurial Lyase MerB: Insight into the Key Role of the Active Site Aspartic Acid in Hg-Carbon Bond Cleavage and Metal Binding Specificity.

Science.gov (United States)

Wahba, Haytham M; Lecoq, Lauriane; Stevenson, Michael; Mansour, Ahmed; Cappadocia, Laurent; Lafrance-Vanasse, Julien; Wilkinson, Kevin J; Sygusch, Jurgen; Wilcox, Dean E; Omichinski, James G

2016-02-23

In bacterial resistance to mercury, the organomercurial lyase (MerB) plays a key role in the detoxification pathway through its ability to cleave Hg-carbon bonds. Two cysteines (C96 and C159; Escherichia coli MerB numbering) and an aspartic acid (D99) have been identified as the key catalytic residues, and these three residues are conserved in all but four known MerB variants, where the aspartic acid is replaced with a serine. To understand the role of the active site serine, we characterized the structure and metal binding properties of an E. coli MerB mutant with a serine substituted for D99 (MerB D99S) as well as one of the native MerB variants containing a serine residue in the active site (Bacillus megaterium MerB2). Surprisingly, the MerB D99S protein copurified with a bound metal that was determined to be Cu(II) from UV-vis absorption, inductively coupled plasma mass spectrometry, nuclear magnetic resonance, and electron paramagnetic resonance studies. X-ray structural studies revealed that the Cu(II) is bound to the active site cysteine residues of MerB D99S, but that it is displaced following the addition of either an organomercurial substrate or an ionic mercury product. In contrast, the B. megaterium MerB2 protein does not copurify with copper, but the structure of the B. megaterium MerB2-Hg complex is highly similar to the structure of the MerB D99S-Hg complexes. These results demonstrate that the active site aspartic acid is crucial for both the enzymatic activity and metal binding specificity of MerB proteins and suggest a possible functional relationship between MerB and its only known structural homologue, the copper-binding protein NosL.

Oxygen- and nitrogen-co-doped activated carbon from waste particleboard for potential application in high-performance capacitance

International Nuclear Information System (INIS)

Shang, Tong-Xin; Ren, Ru-Quan; Zhu, Yue-Mei; Jin, Xiao-Juan

2015-01-01

Graphical abstract: All electrodes showed excellent capacitance and retention versus discharge current density from 0.05 to 5 A/g. - Abstract: Oxygen- and nitrogen-co-doped activated carbons were obtained from phosphoric acid treated nitrogen-doped activated carbons which were prepared from waste particleboard bonded with urea-formaldehyde resin adhesives. The activated carbon samples obtained were tested as supercapacitors in two-electrode cell and extensive wetting 7 M KOH electrolytes. Their structural properties and surface chemistry, before the electrical testing, were investigated using elemental analysis, X-ray photoelectron spectroscopy, scanning electron microscopy, X-ray diffraction, Raman spectra, and adsorption of nitrogen. Activated carbon treated by 4 M phosphoric acid of the highest capacitance (235 F/g) was measured in spite of a relatively lower surface (1360 m 2 /g) than that of the activated carbon treated by 2 M phosphoric acid (1433 m 2 /g). The surface chemistry, and especially oxygen- and nitrogen-containing functional groups, was found of paramount importance for the capacitive behavior and for the effective pore space utilization by the electrolyte ions

High-Level Expression of a Thermally Stable Alginate Lyase Using Pichia pastoris, Characterization and Application in Producing Brown Alginate Oligosaccharide

Directory of Open Access Journals (Sweden)

Haifeng Li

2018-05-01

Full Text Available An alginate lyase encoding gene sagl from Flavobacterium sp. H63 was codon optimized and recombinantly expressed at high level in P.pastoris through high cell-density fermentation. The highest yield of recombinant enzyme of sagl (rSAGL in yeast culture supernatant reached 226.4 μg/mL (915.5 U/mL. This was the highest yield record of recombinant expression of alginate lyase so far. The rSAGL was confirmed as a partially glycosylated protein through EndoH digestion. The optimal reaction temperature and pH of this enzyme were 45 °C and 7.5; 80 mM K+ ions could improve the catalytic activity of the enzyme by 244% at most. rSAGL was a thermal stable enzyme with T5015 of 57–58 °C and T5030 of 53–54 °C. Its thermal stability was better than any known alginate lyase. In 100 mM phosphate buffer of pH 6.0, rSAGL could retain 98.8% of the initial activity after incubation at 50 °C for 2 h. Furthermore, it could retain 61.6% of the initial activity after 48 h. The specific activity of the purified rSAGL produced by P. pastoris attained 4044 U/mg protein, which was the second highest record of alginate lyase so far. When the crude enzyme of the rSAGL was directly used in transformation of sodium alginate with 40 g/L, 97.2% of the substrate was transformed to di, tri, tetra brown alginate oligosaccharide after 32 h of incubation at 50 °C, and the final concentration of reducing sugar in mixture reached 9.51 g/L. This is the first report of high-level expression of thermally stable alginate lyase using P. pastoris system.

Understanding Which Residues of the Active Site and Loop Structure of a Tyrosine Aminomutase Define Its Mutase and Lyase Activities.

Science.gov (United States)

Attanayake, Gayanthi; Walter, Tyler; Walker, Kevin D

2018-05-30

Site-directed mutations and substrate analogues were used to gain insights into the branch-point reaction of the 3,5-dihydro-5-methylidene-4 H-imidazol-4-one (MIO)-tyrosine aminomutase from Oryza sativa ( OsTAM). Exchanging the active residues of OsTAM (Y125C/N446K) for those in a phenylalanine aminomutase TcPAM altered its substrate specificity from tyrosine to phenylalanine. The aminomutase mechanism of OsTAM surprisingly changed almost exclusively to that of an ammonia lyase making cinnamic acid (>95%) over β-phenylalanine [Walter, T., et al. (2016) Biochemistry 55, 3497-3503]. We hypothesized that the missing electronics or sterics on the aryl ring of the phenylalanine substrate, compared with the sizable electron-donating hydroxyl of the natural tyrosine substrate, influenced the unexpected lyase reactivity of the OsTAM mutant. The double mutant was incubated with 16 α-phenylalanine substituent analogues of varying electronic strengths and sterics. The mutant converted each analogue principally to its acrylate with ∼50% conversion of the p-Br substrate, making only a small amount of the β-amino acid. The inner loop structure over the entrance to the active site was also mutated to assess how the lyase and mutase activities are affected. An OsTAM loop mutant, matching the loop residues of TcPAM, still chiefly made >95% of the acrylate from each substrate. A combined active site:loop mutant was most reactive but remained a lyase, making 10-fold more acrylates than other mutants did. While mutations within the active site changed the substrate specificity of OsTAM, continued exploration is needed to fully understand the interplay among the inner loop, the substrate, and the active site in defining the mutase and lyase activities.

Oxycarbonitride phosphors and light emitting devices using the same

Science.gov (United States)

Li, Yuanqiang; Romanelli, Michael Dennis; Tian, Yongchi

2013-10-08

Disclosed herein is a novel family of oxycarbidonitride phosphor compositions and light emitting devices incorporating the same. Within the sextant system of M--Al--Si--O--N--C--Ln and quintuplet system of M--Si--O--N--C--Ln (M=alkaline earth element, Ln=rare earth element), the phosphors are composed of either one single crystalline phase or two crystalline phases with high chemical and thermal stability. In certain embodiments, the disclosed phosphor of silicon oxycarbidonitrides emits green light at wavelength between 530-550 nm. In further embodiments, the disclosed phosphor compositions emit blue-green to yellow light in a wavelength range of 450-650 nm under near-UV and blue light excitation.

The quality study of recycled glass phosphor waste for LED

Science.gov (United States)

Tsai, Chun-Chin; Chen, Guan-Hao; Yue, Cheng-Feng; Chen, Cin-Fu; Cheng, Wood-Hi

2017-02-01

To study the feasibility and quality of recycled glass phosphor waste for LED packaging, the experiments were conducted to compare optical characteristics between fresh color conversion layer and that made of recycled waste. The fresh color conversion layer was fabricated through sintering pristine mixture of Y.A.G. powder [yellow phosphor (Y3AlO12 : Ce3+). Those recycled waste glass phosphor re-melted to form Secondary Molten Glass Phosphor (S.M.G.P.). The experiments on such low melting temperature glass results showed that transmission rates of S.M.G.P. are 9% higher than those of first-sintered glass phosphor, corresponding to 1.25% greater average bubble size and 36% more bubble coverage area in S.M.G.P. In the recent years, high power LED modules and laser projectors have been requiring higher thermal stability by using glass phosphor materials for light mixing. Nevertheless, phosphor and related materials are too expensive to expand their markets. It seems a right trend and research goal that recycling such waste of high thermal stability and quality materials could be preferably one of feasible cost-down solutions. This technical approach could bring out brighter future for solid lighting and light source module industries.

Refeeding syndrome in a young woman with argininosuccinate lyase deficiency

Directory of Open Access Journals (Sweden)

M. Stuy

2015-09-01

Full Text Available A severely chronically protein and calorie restricted young woman with argininosuccinate lyase deficiency developed transient refeeding syndrome (RFS and hyperammonemia after modest diet liberalization following initiation of glycerol phenylbutyrate (GPB. The patient required IV supportive care and supplementation with potassium, magnesium and calcium. She is now doing well on GPB and an appropriate maintenance diet. Susceptibility to RFS should be considered in chronically nutritionally restricted patients with metabolic disorders after liberalization of diet.

Spectral properties of Dy3+ doped ZnAl2O4 phosphor

Science.gov (United States)

Prakash, Ram; Kumar, Sandeep; Mahajan, Rubby; Khajuria, Pooja; Kumar, Vinay; Choudhary, R. J.; Phase, D. M.

2018-05-01

Herein, Dy3+ doped ZnAl2O4 phosphor was synthesized by the solution combustion method. The synthesized phosphor was characterized by X-ray diffraction (XRD), photoluminescence (PL) spectroscopy, UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS). The phase purity of the phosphor was confirmed by the XRD studies that showed cubic symmetry of the synthesized phosphor. Under UV excitation (388 nm) the PL emission spectrum of the phosphor shows characteristic transition from the Dy3+ ion. A band gap of 5.2 eV was estimated from the diffused reflectance spectroscopy. The surface properties of the phosphor were studied using the X-ray photoelectron spectroscopy.

Transcriptional control of monolignol biosynthesis in Pinus taeda: factors affecting monolignol ratios and carbon allocation in phenylpropanoid metabolism

Science.gov (United States)

Anterola, Aldwin M.; Jeon, Jae-Heung; Davin, Laurence B.; Lewis, Norman G.

2002-01-01

Transcriptional profiling of the phenylpropanoid pathway in Pinus taeda cell suspension cultures was carried out using quantitative real time PCR analyses of all known genes involved in the biosynthesis of the two monolignols, p-coumaryl and coniferyl alcohols (lignin/lignan precursors). When the cells were transferred to a medium containing 8% sucrose and 20 mm potassium iodide, the monolignol/phenylpropanoid pathway was induced, and transcript levels for phenylalanine ammonia lyase, cinnamate 4-hydroxylase, p-coumarate 3-hydroxylase, 4-coumarate:CoA ligase, caffeoyl-CoA O-methyltransferase, cinnamoyl-CoA reductase, and cinnamyl alcohol dehydrogenase were coordinately up-regulated. Provision of increasing levels of exogenously supplied Phe to saturating levels (40 mm) to the induction medium resulted in further up-regulation of their transcript levels in the P. taeda cell cultures; this in turn was accompanied by considerable increases in both p-coumaryl and coniferyl alcohol formation and excretion. By contrast, transcript levels for both cinnamate 4-hydroxylase and p-coumarate 3-hydroxylase were only slightly up-regulated. These data, when considered together with metabolic profiling results and genetic manipulation of various plant species, reveal that carbon allocation to the pathway and its differential distribution into the two monolignols is controlled by Phe supply and differential modulation of cinnamate 4-hydroxylase and p-coumarate 3-hydroxylase activities, respectively. The coordinated up-regulation of phenylalanine ammonia lyase, 4-coumarate:CoA ligase, caffeoyl-CoA O-methyltransferase, cinnamoyl-CoA reductase and cinnamyl alcohol dehydrogenase in the presence of increasing concentrations of Phe also indicates that these steps are not truly rate-limiting, because they are modulated according to metabolic demand. Finally, the transcript profile of a putative acid/ester O-methyltransferase, proposed as an alternative catalyst for O-methylation leading

Thermal and Electrical Conductivity Measurements of CDA 510 Phosphor Bronze

Science.gov (United States)

Tuttle, James E.; Canavan, Edgar; DiPirro, Michael

2009-01-01

Many cryogenic systems use electrical cables containing phosphor bronze wire. While phosphor bronze's electrical and thermal conductivity values have been published, there is significant variation among different phosphor bronze formulations. The James Webb Space Telescope (JWST) will use several phosphor bronze wire harnesses containing a specific formulation (CDA 510, annealed temper). The heat conducted into the JWST instrument stage is dominated by these harnesses, and approximately half of the harness conductance is due to the phosphor bronze wires. Since the JWST radiators are expected to just keep the instruments at their operating temperature with limited cooling margin, it is important to know the thermal conductivity of the actual alloy being used. We describe an experiment which measured the electrical and thermal conductivity of this material between 4 and 295 Kelvin.

High temperature thermometric phosphors for use in a temperature sensor

Science.gov (United States)

Allison, Stephen W.; Cates, Michael R.; Boatner, Lynn A.; Gillies, George T.

1998-01-01

A high temperature phosphor consists essentially of a material having the general formula LuPO.sub.4 :Dy.sub.(x),Eu.sub.(y), wherein: 0.1 wt %.ltoreq.x.ltoreq.20 wt % and 0.1 wt %.ltoreq.y.ltoreq.20 wt %. The high temperature phosphor is in contact with an article whose temperature is to be determined. The article having the phosphor in contact with it is placed in the environment for which the temperature of the article is to be determined. The phosphor is excited by a laser causing the phosphor to fluoresce. The emission from the phosphor is optically focused into a beam-splitting mirror which separates the emission into two separate emissions, the emission caused by the dysprosium dopant and the emission caused by the europium dopent. The separated emissions are optically filtered and the intensities of the emission are detected and measured. The ratio of the intensity of each emission is determined and the temperature of the article is calculated from the ratio of the intensities of the separate emissions.

On the feasibility of infrared phosphors in super-slow particle searches

International Nuclear Information System (INIS)

Hagstrom, R.; Rugari, A.D.

1984-01-01

This chapter proposes that super-slow projectiles will produce ionization signals in media with narrow bandgaps. A specific choice of narrow bandgap phosphors is recommended which would be economically suitable for use as detectors. Topics considered include the possibilities for practical detectors, a description of detectors based on narrow bandgap phosphors, the experimental determination of relevant properties of narrow bandgap phosphors, and the observation of ionizing particles using narrow bandgap phosphors. It is determined that the temperature dependence of the glow of the phosphors is strong enough that a reduction of operating temperature by about 60 C could be sufficient to produce the desired signal to background ratio

Recuperation of uranium from phosphoric acid

International Nuclear Information System (INIS)

Cordero, G.; Jodra, L.G.; Otero, J.L.; Josa, J.M.

1977-01-01

The Spanish capacity for phosphoric acid production is 500.000 t P 2 O 5 /yr. This acid has an average concentration of 365 g U 3 O 8 / t P 2 O 5 . Therefore about 180 t U 3 O 8 /yr are dissolved. In 1969, the Junta de Energia Nuclear (JEN) developed, in bench scale, a solvent extraction process to recover the uranium from the phosphoric acid. The solvent used was a synergistic mixture of D2EHPA and TOPO. The results were very promising with good recovery and very high quality for the uranium concentrate. Later, the J.E.N. continued the studies in a pilot plant scale. For this purpose, was built an experimental facility in Huelva; it can treat about 7 cu. m/day of brown acid. Fosforico Espanol, S.A. (FESA) collaborated in the studies and agreed to setting up these installations in their factory. They also provided fresh phosphoric acid for the tests. In this pilot plant we studied the following stages: a) Clarification and conditioning of the phosphoric acid; b) Uranium extraction followed by stripping in a reducing medium; c) Purification by extraction and washing; d) Obtention of the concentrate by stripping with ammonia and CO 2 gas, followed by crystallization of the ammonium uranyl tricarbonate (AUT); and e) Calcination of the concentrate to decompose the AUT to uranium oxides. The results confirmed the laboratory test data. Recuperation levels were between 85 and 90%. The AUT calcined at 550 0 C. gave a product with 96-98% U 3 O 8 . In view of the pilot plant results we have prepared a black book for an industrial plant to treat about 3700 cu. m/day of phosphoric acid. At the present time the financial aspects of this installation are being studied [es

Process for recovering yttrium and lanthanides from wet-process phosphoric acid

Energy Technology Data Exchange (ETDEWEB)

Janssen, J.A.; Weterings, C.A.

1983-06-28

Process for recovering yttrium and lanthanides from wet-process phosphoric acid by adding a flocculant to the phosphoric acid, separating out the resultant precipitate and then recovering yttrium and lanthanides from the precipitate. Uranium is recovered from the remaining phosphoric acid.

Development of BaSO4:Eu thermoluminescence phosphor

International Nuclear Information System (INIS)

Madhusoodanan, U.; Jose, M.T.; Lakshmanan, A.R.

1999-01-01

A highly sensitive thermoluminescence (TL) phosphor based on BaSO 4 :Eu was developed following the coprecipitation technique and firing in argon atmosphere at 1123 K. Photoluminescence studies confirm that firing in argon atmosphere instead of air increased the incorporation of Eu ions in 2+ valence state. At low γ-ray doses, its TL sensitivity is nearly 2 to 3 times higher than that of CaSO 4 :Dy phosphor. The other salient features of this BaSO 4 :Eu TL phosphor are a constant glow curve shape and a nearly linear γ-ray dose response

Counter current extraction of phosphoric acid: Food grade acid production

International Nuclear Information System (INIS)

Shlewit, H.; AlIbrahim, M.

2009-01-01

Extraction, scrubbing and stripping of phosphoric acid from the Syrian wet-phosphoric acid was carried out using Micro-pilot plant of mixer settler type of 8 l/h capacity. Tributyl phosphate (TBP)/di-isopropyl ether (DIPE) in kerosene was used as extractant. Extraction and stripping equilibrium curves were evaluated. The number of extraction and stripping stages to achieve the convenient and feasible yield was determined. Detailed flow sheet was suggested for the proposed continuous process. Data obtained include useful information for the design of phosphoric acid extraction plant. The produced phosphoric acid was characterized using different analytical techniques. (author)

Point defect engineering strategies to retard phosphorous diffusion in germanium

KAUST Repository

Tahini, H. A.; Chroneos, Alexander I.; Grimes, Robin W.; Schwingenschlö gl, Udo; Bracht, Hartmut A.

2013-01-01

The diffusion of phosphorous in germanium is very fast, requiring point defect engineering strategies to retard it in support of technological application. Density functional theory corroborated with hybrid density functional calculations are used to investigate the influence of the isovalent codopants tin and hafnium in the migration of phosphorous via the vacancy-mediated diffusion process. The migration energy barriers for phosphorous are increased significantly in the presence of oversized isovalent codopants. Therefore, it is proposed that tin and in particular hafnium codoping are efficient point defect engineering strategies to retard phosphorous migration. © the Owner Societies 2013.

Phosphor Scanner For Imaging X-Ray Diffraction

Science.gov (United States)

Carter, Daniel C.; Hecht, Diana L.; Witherow, William K.

1992-01-01

Improved optoelectronic scanning apparatus generates digitized image of x-ray image recorded in phosphor. Scanning fiber-optic probe supplies laser light stimulating luminescence in areas of phosphor exposed to x rays. Luminescence passes through probe and fiber to integrating sphere and photomultiplier. Sensitivity and resolution exceed previously available scanners. Intended for use in x-ray crystallography, medical radiography, and molecular biology.

Synthesis of carbon-13 labeled ibuprofen

International Nuclear Information System (INIS)

Hsi, R.S.P.; Stelzer, L.S.; Stolle, W.T.

1989-01-01

This report describes the synthesis of 2-[4-(2-methyl)propyl-phenyl]propionic acid (ibuprofen) labeled with carbon-13 either at the terminal methyl carbons, or at the methine carbon of the isobutyl side chain. The synthetic route involves the removal of the isopropyl group in the isobutyl side-chain of ibuprofen via 2-[4-(2-methyl-1-propenyl)phenyl]propionic acid, followed by restoration of the isopropyl group with a Wittig reaction, using appropriate carbon-13 labeled acetone as the precursor of the isopropyl group. Interesting NMR coupling data attributable to phosphorous and carbon-13 are presented in the experimental section. (author)

Synthesis and luminescence properties of Eu"2"+ doped CaSO_4 phosphor

International Nuclear Information System (INIS)

Aghalte, G.A.; Dhoble, S.J.; Pawar, N.R.

2016-01-01

Eu"2"+ doped CaSO_4 Phosphor were synthesized by precipitation method. PL analysis of Eu"2"+ activated CaSO_4 phosphor exhibited characteristic emission properties; CaSO_4:Eu Phosphor has received considerable attention because of its high sensitivity to X-ray and λ ray irradiation. CaSO_4:Eu phosphor powder was successfully synthesized by the wet chemical co-precipitation method. The structure morphology and luminescent properties of the phosphor were characterized by X-ray diffraction, scanning electron microscopy and photoluminescence spectroscopy

A Pectate Lyase-Coding Gene Abundantly Expressed during Early Stages of Infection Is Required for Full Virulence in Alternaria brassicicola.

Directory of Open Access Journals (Sweden)

Yangrae Cho

Full Text Available Alternaria brassicicola causes black spot disease of Brassica species. The functional importance of pectin digestion enzymes and unidentified phytotoxins in fungal pathogenesis has been suspected but not verified in A. brassicicola. The fungal transcription factor AbPf2 is essential for pathogenicity and induces 106 genes during early pathogenesis, including the pectate lyase-coding gene, PL1332. The aim of this study was to test the importance and roles of PL1332 in pathogenesis. We generated deletion strains of the PL1332 gene, produced heterologous PL1332 proteins, and evaluated their association with virulence. Deletion strains of the PL1332 gene were approximately 30% less virulent than wild-type A. brassicicola, without showing differences in colony expansion on solid media and mycelial growth in nutrient-rich liquid media or minimal media with pectins as a major carbon source. Heterologous PL1332 expressed as fusion proteins digested polygalacturons in vitro. When the fusion proteins were injected into the apoplast between leaf veins of host plants the tissues turned dark brown and soft, resembling necrotic leaf tissue. The PL1332 gene was the first example identified as a general toxin-coding gene and virulence factor among the 106 genes regulated by the transcription factor, AbPf2. It was also the first gene to have its functions investigated among the 19 pectate lyase genes and several hundred putative cell-wall degrading enzymes in A. brassicicola. These results further support the importance of the AbPf2 gene as a key pathogenesis regulator and possible target for agrochemical development.

Purification of di-nonyl phenyl phosphoric acid (DNPPA) for synergistic extraction of uranium from strong phosphoric acid

International Nuclear Information System (INIS)

Singh, D.K.; Vijayalakshmi, R.; Singh, H.; Sharma, J.N.; Ruhela, R.

2009-01-01

Di-nonyl phenyl phosphoric acid (DNPPA) obtained from various synthesis methods is always associated with impurities such as mono-nonyl phenyl phosphoric acid and nonyl phenol which need to be separated for its effective use in the extraction of uranium from strong phosphoric acid. Two methods of purification namely liquid-solid separation method using neodymium salt and liquid-liquid separation method using methylene glycol have been described. In the liquid solid separation method the purity of DNPPA obtained was about 95% with less than 1.0% monoester, however it heavily suffers in the recovery aspect which is of the order of 50-60%. The methylene glycol treatment method, results in high purity and recovery of the product. Purity obtained was about 95.0% diester and less than 0.5% monoester and recovery was more than 90%. Analysis of DNPPA was done by potentiometric titration method using autotitrator. (author)

Regulation of expression of pectate lyase genes pelA, pelD, and pelE in Erwinia chrysanthemi.

Science.gov (United States)

Reverchon, S; Robert-Baudouy, J

1987-06-01

The regulation of pelA, pelD, and pelE genes encoding three of the five major pectate lyase isoenzymes (PLa, PLd, and PLe) in Erwinia chrysanthemi B374 was analyzed by using genetic fusions to lacZ. These three genes are clustered on a 5-kilobase DNA fragment in the order pelD-pelE-pelA and constitute three independent transcriptional units. We localized the pelDEA cluster near the pro-1 marker on the genetic map of B374 by chromosomal mobilization with RP4::mini-Mu plasmid pULB110. Three classes of regulatory mutations responsible for constitutive pectate lyase synthesis have been described (kdgR, gpiR, and cri). We studied the effects of each mutation on pelE, pelD, and pelA expression independently. The mutations kdgR and gpiR mainly affect the expression of pelE and pelD, although PLa synthesis is slightly increased. The cri mutation results in a low level of constitutive expression of the three pel genes, but it is a pleiotropic mutation since other genes not involved in pectinolysis are also affected. In addition, we demonstrated that exuR, a negative regulatory gene governing the catabolism of hexuronates, does not modify the expression of pel genes. The frequency of gpiR or cri mutations (about 10(-8)) and the resulting constitutivity of pectate lyase synthesis suggest that these genes act as negative regulatory genes in addition to kdgR, which is already known to encode a repressor. Moreover, we found that expression of pel-lac fusions carried on pBR322 derivatives was higher in E. chrysanthemi than in Escherichia coli; this fact suggests the existence of positive regulation of pectate lyase synthesis in E. chrysanthemi.

Rhodococcus erythropolis DCL14 Contains a Novel Degradation Pathway for Limonene

Science.gov (United States)

van der Werf, Mariët J.; Swarts, Henk J.; de Bont, Jan A. M.

1999-01-01

Strain DCL14, which is able to grow on limonene as a sole source of carbon and energy, was isolated from a freshwater sediment sample. This organism was identified as a strain of Rhodococcus erythropolis by chemotaxonomic and genetic studies. R. erythropolis DCL14 also assimilated the terpenes limonene-1,2-epoxide, limonene-1,2-diol, carveol, carvone, and (−)-menthol, while perillyl alcohol was not utilized as a carbon and energy source. Induction tests with cells grown on limonene revealed that the oxygen consumption rates with limonene-1,2-epoxide, limonene-1,2-diol, 1-hydroxy-2-oxolimonene, and carveol were high. Limonene-induced cells of R. erythropolis DCL14 contained the following four novel enzymatic activities involved in the limonene degradation pathway of this microorganism: a flavin adenine dinucleotide- and NADH-dependent limonene 1,2-monooxygenase activity, a cofactor-independent limonene-1,2-epoxide hydrolase activity, a dichlorophenolindophenol-dependent limonene-1,2-diol dehydrogenase activity, and an NADPH-dependent 1-hydroxy-2-oxolimonene 1,2-monooxygenase activity. Product accumulation studies showed that (1S,2S,4R)-limonene-1,2-diol, (1S,4R)-1-hydroxy-2-oxolimonene, and (3R)-3-isopropenyl-6-oxoheptanoate were intermediates in the (4R)-limonene degradation pathway. The opposite enantiomers [(1R,2R,4S)-limonene-1,2-diol, (1R,4S)-1-hydroxy-2-oxolimonene, and (3S)-3-isopropenyl-6-oxoheptanoate] were found in the (4S)-limonene degradation pathway, while accumulation of (1R,2S,4S)-limonene-1,2-diol from (4S)-limonene was also observed. These results show that R. erythropolis DCL14 metabolizes both enantiomers of limonene via a novel degradation pathway that starts with epoxidation at the 1,2 double bond forming limonene-1,2-epoxide. This epoxide is subsequently converted to limonene-1,2-diol, 1-hydroxy-2-oxolimonene, and 7-hydroxy-4-isopropenyl-7-methyl-2-oxo-oxepanone. This lactone spontaneously rearranges to form 3-isopropenyl-6-oxoheptanoate. In

Self-adaptive phosphor coating technology for wafer-level scale chip packaging

International Nuclear Information System (INIS)

Zhou Linsong; Rao Haibo; Wang Wei; Wan Xianlong; Liao Junyuan; Wang Xuemei; Zhou Da; Lei Qiaolin

2013-01-01

A new self-adaptive phosphor coating technology has been successfully developed, which adopted a slurry method combined with a self-exposure process. A phosphor suspension in the water-soluble photoresist was applied and exposed to LED blue light itself and developed to form a conformal phosphor coating with self-adaptability to the angular distribution of intensity of blue light and better-performing spatial color uniformity. The self-adaptive phosphor coating technology had been successfully adopted in the wafer surface to realize a wafer-level scale phosphor conformal coating. The first-stage experiments show satisfying results and give an adequate demonstration of the flexibility of self-adaptive coating technology on application of WLSCP. (semiconductor devices)

Adsorption of volatile organic compounds by pecan shell- and almond shell-based granular activated carbons.

Science.gov (United States)

Bansode, R R; Losso, J N; Marshall, W E; Rao, R M; Portier, R J

2003-11-01

The objective of this research was to determine the effectiveness of using pecan and almond shell-based granular activated carbons (GACs) in the adsorption of volatile organic compounds (VOCs) of health concern and known toxic compounds (such as bromo-dichloromethane, benzene, carbon tetrachloride, 1,1,1-trichloromethane, chloroform, and 1,1-dichloromethane) compared to the adsorption efficiency of commercially used carbons (such as Filtrasorb 200, Calgon GRC-20, and Waterlinks 206C AW) in simulated test medium. The pecan shell-based GACs were activated using steam, carbon dioxide or phosphoric acid. An almond shell-based GAC was activated with phosphoric acid. Our results indicated that steam- or carbon dioxide-activated pecan shell carbons were superior in total VOC adsorption to phosphoric acid-activated pecan shell or almond shell carbons, inferring that the method of activation selected for the preparation of activated carbons affected the adsorption of VOCs and hence are factors to be considered in any adsorption process. The steam-activated, pecan shell carbon adsorbed more total VOCs than the other experimental carbons and had an adsorption profile similar to the two coconut shell-based commercial carbons, but had greater adsorption than the coal-based commercial carbon. All the carbons studied adsorbed benzene more effectively than the other organics. Pecan shell, steam-activated and acid-activated GACs showed higher adsorption of 1,1,1-trichloroethane than the other carbons studied. Multivariate analysis was conducted to group experimental carbons and commercial carbons based on their physical, chemical, and adsorptive properties. The results of the analysis conclude that steam-activated and acid-activated pecan shell carbons clustered together with coal-based and coconut shell-based commercial carbons, thus inferring that these experimental carbons could potentially be used as alternative sources for VOC adsorption in an aqueous environment.

Pathways of carbon oxidation in continental margin sediments off central Chile

DEFF Research Database (Denmark)

Thamdrup, B; Canfield, Donald Eugene

1996-01-01

Rates and oxidative pathways of organic carbon mineralization were determined in sediments at six stations on the shelf and slope off Concepcion Bay at 36.5 degrees S. The depth distribution of C oxidation rates was determined to 10 cm from accumulation of dissolved inorganic C in 1-5-d incubations...... the shelf was rich in NO3- and depleted of O2. Sediments at the four shelf stations were covered by mats of filamentous bacteria of the genera Thioploca and Beggiatoa. Carbon oxidation rates at these sites were extremely high near the sediment surface (>3 micromol cm-3 d-1) and decreased exponentially...... C oxidation between 0 and 10 cm. Carbon oxidation through Fe reduction contributed a further 12-29% of the depth-integrated rate, while the remainder of C oxidation was through SO4(2-) reduction. The depth distribution of Fe reduction agreed well with the distribution of poorly crystalline Fe oxides...

De Novo Biosynthesis of Glutarate via α-Keto Acid Carbon Chain Extension and Decarboxylation Pathway in Escherichia coli.

Science.gov (United States)

Wang, Jian; Wu, Yifei; Sun, Xinxiao; Yuan, Qipeng; Yan, Yajun

2017-10-20

Microbial based bioplastics are promising alternatives to petroleum based synthetic plastics due to their renewability and economic feasibility. Glutarate is one of the most potential building blocks for bioplastics. The recent biosynthetic routes for glutarate were mostly based on the l-lysine degradation pathway from Pseudomonas putida that required lysine either by feeding or lysine overproduction via genetic manipulations. Herein, we established a novel glutarate biosynthetic pathway by incorporation of a "+1" carbon chain extension pathway from α-ketoglutarate (α-KG) in combination with α-keto acid decarboxylation pathway in Escherichia coli. Introduction of homocitrate synthase (HCS), homoaconitase (HA) and homoisocitrate dehydrogenase (HICDH) from Saccharomyces cerevisiae into E. coli enabled "+1" carbon extension from α-KG to α-ketoadipate (α-KA), which was subsequently converted into glutarate by a promiscuous α-keto acid decarboxylase (KivD) and a succinate semialdehyde dehydrogenase (GabD). The recombinant E. coli coexpressing all five genes produced 0.3 g/L glutarate from glucose. To further improve the titers, α-KG was rechanneled into carbon chain extension pathway via the clustered regularly interspersed palindromic repeats system mediated interference (CRISPRi) of essential genes sucA and sucB in tricarboxylic acid (TCA) cycle. The final strain could produce 0.42 g/L glutarate, which was increased by 40% compared with the parental strain.

Low lag luminescent phosphors

International Nuclear Information System (INIS)

1976-01-01

The addition of potassium or rubidium salts to europium-activated fluorohalide phosphors produces X-ray screens with low lag, even at very low europium concentrations. The chemical preparation and afterglow test results are described

New lupane triterpenoids from Solidago canadensis that inhibit the lyase activity of DNA polymerase beta.

Science.gov (United States)

Chaturvedula, V S Prakash; Zhou, Bing-Nan; Gao, Zhijie; Thomas, Shannon J; Hecht, Sidney M; Kingston, David G I

2004-12-01

Bioassay-directed fractionation of a methyl ethyl ketone extract of Solidago canadensis L. (Asteraceae), using an assay to detect the lyase activity of DNA polymerase beta, resulted in the isolation of the four new lupane triterpenoids 1-4 and the seven known compounds lupeol, lupeyl acetate, ursolic acid, cycloartenol, cycloartenyl palmitate, alpha-amyrin acetate, and stigmasterol. The structures of the new compounds were established as 3beta-(3R-acetoxyhexadecanoyloxy)-lup-20(29)-ene (1), 3beta-(3-ketohexadecanoyloxy)-lup-20(29)-ene (2), 3beta-(3R-acetoxyhexadecanoyloxy)-29-nor-lupan-20-one (3), and 3beta-(3-hetohexadecanoyloxy)-29-nor-lupan-20-one (4), respectively, on the basis of extensive 1D and 2D NMR spectroscopic interpretation and chemical modification studies. All 11 compounds were inhibitory to the lyase activity of DNA polymerase beta.

Synthesis of Eu3+-doped calcium and strontium carbonate phosphors at room temperature

International Nuclear Information System (INIS)

Pan Yuexiao; Wu Mingmei; Su Qiang

2003-01-01

Red phosphors CaCO 3 :Eu 3+ and SrCO 3 :Eu 3+ have been prepared by co-precipitation with ammonium bicarbonate (NH 4 HCO 3 ) at room temperature. Pure calcite CaCO 3 can be obtained by prolonging the reaction time at 220 deg. C and it decomposes to cubic CaO at 1000 deg. C. Trivalent Eu 3+ acts as a luminescent probe to determine both the calcite and the mixed phase of calcite and vaterite phase of CaCO 3 host and to analyze its decomposition process. High temperature sintering improved both the crystallization and luminescence of SrCO 3 :Eu 3+ in aragonite phase

Color deviations in phosphor converted high power light emitting diodes under different dimming schemes

International Nuclear Information System (INIS)

Ludwiczak, Bogna; Jantsch, Wolfgang

2015-01-01

We investigate experimentally the color stability of high power phosphor converted InGaN LEDs under pulse width modulation (PWM) and continuous current reduction (CCR) dimming modes and for varied operation temperatures. Our measurements reveal that the chromaticity coordinate pathways of the warm white and the cold white LED's differ for the same operation conditions. The color deviation- minimizing phenomenon of opposite peak wavelength shifts appears only for a cold white LED under CCR driving mode. This favorable effect does not occur for warm white LEDs. This type of LED exhibits the best color stability under PWM driving mode. The experimental results are consistently explained in terms of the quantum confined Stark effect and temperature induced changes of the LED emission. - Highlights: • Cold and warm white LEDs reacts colorimetrically unlike in different driving modes. • For cold white emission driving conditions are crucial. • Opposite peak wavelength shifts reduces color deviations for cold white emission. • For warm white emission rather phosphor properties determines color deviations

Comparison between mixed and spatially separated remote phosphor fabricated via a screen-printing process

Science.gov (United States)

Kim, Byung-Ho; Hwang, Jonghee; Lee, Young Jin; Kim, Jin-Ho; Jeon, Dae-Woo; Lee, Mi Jai

2016-08-01

We developed a fabrication method for remote phosphor by a screen-printing process, using green phosphor, red phosphor, and thermally stable glass frit. The glass frit was introduced for long-term stability. The optical properties of the remote phosphor were observed via an integrating sphere; the photoluminescence spectrum dramatically changed on incorporating a minor amount of the red phosphor. These unique optical properties were elucidated using four factors: phosphor ratio, scattering induced by packing density, light intensity per unit volume, and reabsorption. The thermal stability of the remote phosphor was investigated at 500°C, demonstrating its outstanding thermal properties.

Luminescent properties of phosphor converted LED using an orange-emitting Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} phosphor

Energy Technology Data Exchange (ETDEWEB)

Song, Hee Jo; Yim, Dong Kyun [Department of Materials Science and Engineering, College of Engineering, Seoul National University, Daehak-dong, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Cho, In-Sun [Department of Mechanical Engineering, Stanford University, CA 94305 (United States); Roh, Hee-Suk; Kim, Ju Seong [Department of Materials Science and Engineering, College of Engineering, Seoul National University, Daehak-dong, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Kim, Dong-Wan, E-mail: dwkim@ajou.ac.kr [Department of Materials Science and Engineering, Ajou University, Woncheon-dong, San 5, Yeongtong-gu, Suwon 443-749 (Korea, Republic of); Hong, Kug Sun, E-mail: kshongss@plaza.snu.ac.kr [Department of Materials Science and Engineering, College of Engineering, Seoul National University, Daehak-dong, Gwanak-gu, Seoul 151-744 (Korea, Republic of)

2012-12-15

Graphical abstract: Display Omitted Highlights: ► Phase-pure Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} powders were synthesized by a solid state reaction process. ► The optimum emission intensity was observed at the Eu{sup 2+} ion concentration of 0.006. ► The dipole–dipole interaction was the major concentration quenching mechanism. ► The pc-LED coated with Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} had higher CRI than commercial red phosphor. -- Abstract: A series of orange-emitting Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} phosphors were synthesized by a conventional solid-state reaction method. The as-prepared phosphors were characterized by X-ray powder diffraction (XRD), fluorescence spectroscopy, and spectroradiometry. XRD showed that all prepared samples exhibited a monoclinic Rb{sub 2}CaP{sub 2}O{sub 7} phase. Fluorescence spectroscopy showed that the photoluminescence efficiency of Rb{sub 2}Ca{sub 1−x}P{sub 2}O{sub 7}:Eu{sub x}{sup 2+} phosphors increased with increasing Eu{sup 2+} concentration until x = 0.006, then decreased at higher concentrations, due to a concentration quenching effect. The thermal activation energy was also measured to be 0.40 eV. Furthermore, a phosphor-converted LED (pc-LED) coated with Rb{sub 2}Ca{sub 0.994}P{sub 2}O{sub 7}:Eu{sub 0.006}{sup 2+} was fabricated, which exhibited bright orange emission under a forward bias, from 200 to 300 mA. The color rendering index (CRI) of pc-LED coated with Rb{sub 2}Ca{sub 0.994}P{sub 2}O{sub 7}:Eu{sub 0.006}{sup 2+} was higher than the CRI of pc-LED coated with commercial red phosphor, due to the broad emission band of Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} phosphor. In applying with three-band pc-LEDs, moreover, white pc-LED using Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} phosphor had a higher CRI, than using commercial phosphor. These results indicated that Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} phosphor could be a good candidate for a near-UV based w-LED.

Recovering of uranium from phosphoric acid produced by the wet process

International Nuclear Information System (INIS)

Barreiro, A.J.; Lyon, W.L.; Holleman, R.A.; Randell, C.C.

1977-01-01

Process for recovering uranium as from an aqueous solution of phosphoric acid arising from a wet process, with a scrubbing agent essentially composed of a hydrocarbon whose boiling point is situated between 150 0 C and 300 0 C, which reacts with the contaminents formed in the sludge in the phosphoric acid, in an efficient enough quantity to wash the contamination products forming the phosphoric acid sludge, give a sludge phase and a purified phosphoric acid phase, after which the sludge phase is extracted [fr

Synthesis of novel Dy3+ activated phosphate phosphors for NUV excited LED

International Nuclear Information System (INIS)

Shinde, K.N.; Dhoble, S.J.; Kumar, Animesh

2011-01-01

The new trivalent dysprosium activated X 6 AlP 5 O 20 (where X=Sr, Ba, Ca and Mg) phosphors were prepared by the combustion method. The prepared phosphors are characterized by XRD, photoluminescence and SEM techniques. Excited by 350 nm near-ultraviolet (NUV) light, the phosphors show an efficient blue and yellow band emissions, which originates from the 4 F 9/2 → 6 H 15/2 and 4 F 9/2 → 6 H 13/2 transitions of Dy 3+ ion, respectively. The excitation spectra of the phosphors are broadband extending from 340 to 400 nm, which are characteristics of NUV excited LED. The effect of the Dy 3+ concentration on the luminescence properties of X 6 AlP 5 O 20 :Dy 3+ (where X=Sr, Ba, Ca and Mg) phosphors is studied. Ca 6 AlP 5 O 20 phosphors show strong PL emission intensity around 25 times more as compared to Ba 6 AlP 5 O 20 , Sr 6 AlP 5 O 20 and Mg 6 AlP 5 O 20 phosphors. The investigated prepared phosphors are suitable for a NUV excited LED. - Research highlights: → Novel Dy 3+ activated X 6 AlP 5 O 20 (where X=Sr,Ba,Ca and Mg) phosphors were prepared by combustion method which is very low cost and time saving synthesis method. → The excitation spectra of the phosphors are broad band extending from 340 nm to 400 nm, which is characteristics of NUV excited LED. → PL emission spectra show two emissions (485 and 573 nm) and X 6 AlP 5 O 20 :Dy 3+ 0.5 mol% (where X=Sr,Ba,Ca and Mg) phosphors shows strongest PL emission intensity. → SEM analysis indicates that phosphor particles have irregular shape, porous morphology and less than 3-4 μm in size, which is suitable for the solid state lighting (coating purpose).

Blue emitting KSCN:xCe phosphor for solid state lighting

Energy Technology Data Exchange (ETDEWEB)

Chikte, Devayani, E-mail: devi.awade@gmail.com [G.N. Khalsa College, Matunga, Mumbai 400019 (India); Omanwar, S.K. [Department of Physics, S.G.B. Amravati University, Amravati (India); Moharil, S.V. [Department of Physics, R.T.M. Nagpur University, Nagpur 440010 (India)

2014-01-15

The intense blue emitting phosphor KSCN:xCe (x=0.005, 0.01, 0.02, 0.04) is synthesized by a simple, time saving, economical method of re-crystallization through aqueous solution at 353 K. Photoluminescence measurements showed that the said phosphor exhibits emission with good intensity peaking at 450 nm corresponding to d→f transitions of Ce{sup 3+} ion. The excitation spectra monitored at 450 nm shows small peak at 282 nm and broad intense excitation band peaking at 350 nm. The latter lies in near ultraviolet (350–410 nm) emission of UV LED. The phosphor KSCN:0.02Ce{sup 3+} shows CIE 1931 color coordinates as (0.1484, 0.0602) whereas the commercial blue phosphor BAM:Eu{sup 2+} shows the color co-ordinates as (0.1417, 0.1072), respectively, indicating better color purity for KSCN: 0.02Ce{sup 3+} compared to the BAM:Eu{sup 2+} phosphor. The color coordinates of KSCN: 0.02Ce{sup 3+} phosphor (0.1484, 0.0602) are nearer to the color coordinate for blue color suggested by the color systems EBUPAL/SECAM, sRGB Blue as well as Adobe blue(0.15, 0.06). -- Highlights: • Novel phosphor KSCN:xCe prepared for the first time. • Method is simple, time saving, economical, easy to handle. • Intense, blue, Characteristic Ce{sup 3+} emission at 450 nm. • nUV excitation, suitable for solid state lighting.

Neutron scintillator using Ga-doped ZnO phosphor with high detection efficiency

International Nuclear Information System (INIS)

Koyama, Shin; Kinoshita, Atsushi; Fujiwara, Akihiko; Kobayashi, Haruki; Takei, Yoshinori; Nanto, Hidehito; Katagiri, Masaki

2009-01-01

Zinc Oxide (ZnO) family phosphors as phosphor for neutron detector have prepared using Spark Plasma Sintering (SPS) method. The optical properties of ZnO phosphor prepared are investigated. The following results were obtained. Two dominant photoluminescence (PL) emission peaks at 395 nm and 495 nm were observed. The lifetime of the PL emission peak at 395 nm (UV emission band) is about 20 ns, which is suitable for neutron detection. The Ga (30 mol%)-doped ZnO phosphor exhibited an intense UV emission band without the visible emission band. The Ga-doped ZnO phosphor can be prepared at the atmospheric pressure of about 8 Pa using SPS method. It was found that the PL intensity of UV emission band is increased with improving the crystallinity of the ZnO phosphor. (author)

Modes of carbon fixation in an arsenic and CO₂-rich shallow hydrothermal ecosystem

DEFF Research Database (Denmark)

Callac, Nolwenn; Posth, Nicole R.; Rattray, Jayne E.

2017-01-01

for autotrophic carbon fixation used in the Calvin-Benson-Bassham (CBB) and reverse tricaboxylic acid (rTCA) cycles. Both forms of RuBisCO, together with ATP citrate lyase genes in the rTCA cycle, increase with distance from the active hydrothermal centres and decrease with sediment depth. Clustering of Ru...

Hydrogen Peroxide Treatment and the Phenylpropanoid Pathway Precursors Feeding Improve Phenolics and Antioxidant Capacity of Quinoa Sprouts via an Induction of L-Tyrosine and L-Phenylalanine Ammonia-Lyases Activities

Directory of Open Access Journals (Sweden)

Michał Świeca

2016-01-01

Full Text Available Hydrogen peroxide treatment and the phenylpropanoid pathway precursors feeding affected the antioxidant capacity of quinoa sprouts. Compared to the control, total phenolics content was significantly increased by treatment of control sprouts with 50 mM and 200 mM H2O2—an elevation of about 24% and 28%, respectively. The highest increase of flavonoids content was found for the sprouts treated with 200 mM H2O2 obtained from seeds fed with shikimic acid. All the studied modifications increased the antioxidant potential of sprouts (at least by 50% compared to control. The highest reducing power was found for the sprouts treated with 200 mM H2O2 obtained by phenylalanine feeding (5.03 mg TE/g DW and those obtained from the seeds fed with tyrosine (5.26 mg TE/g DW. The activities of L-tyrosine (TAL and L-phenylalanine (PAL ammonia-lyases were strongly affected by germination time as well as the applied modification of sprouting. On the 3rd day the highest PAL activity was determined for both untreated and induced with 50 mM H2O2 sprouts obtained by phenylalanine feeding. H2O2 induced TAL activity; the highest TAL activity was determined for 3-day-old sprouts induced with 200 mM H2O2 obtained from seeds fed with phenylalanine.

Light Converting Inorganic Phosphors for White Light-Emitting Diodes

Directory of Open Access Journals (Sweden)

Chiao-Wen Yeh

2010-03-01

Full Text Available White light-emitting diodes (WLEDs have matched the emission efficiency of florescent lights and will rapidly spread as light source for homes and offices in the next 5 to 10 years. WLEDs provide a light element having a semiconductor light emitting layer (blue or near-ultraviolet (nUV LEDs and photoluminescence phosphors. These solid-state LED lamps, rather than organic light emitting diode (OLED or polymer light-emitting diode (PLED, have a number of advantages over conventional incandescent bulbs and halogen lamps, such as high efficiency to convert electrical energy into light, reliability and long operating lifetime. To meet with the further requirement of high color rendering index, warm light with low color temperature, high thermal stability and higher energy efficiency for WLEDs, new phosphors that can absorb excitation energy from blue or nUV LEDs and generate visible emissions efficiently are desired. The criteria of choosing the best phosphors, for blue (450-480 nm and nUV (380-400 nm LEDs, strongly depends on the absorption and emission of the phosphors. Moreover, the balance of light between the emission from blue-nUV LEDs and the emissions from phosphors (such as yellow from Y3Al5O12:Ce3+ is important to obtain white light with proper color rendering index and color temperature. Here, we will review the status of phosphors for LEDs and prospect the future development.

Light Converting Inorganic Phosphors for White Light-Emitting Diodes

Science.gov (United States)

Chen, Lei; Lin, Chun-Che; Yeh, Chiao-Wen; Liu, Ru-Shi

2010-01-01

White light-emitting diodes (WLEDs) have matched the emission efficiency of florescent lights and will rapidly spread as light source for homes and offices in the next 5 to 10 years. WLEDs provide a light element having a semiconductor light emitting layer (blue or near-ultraviolet (nUV) LEDs) and photoluminescence phosphors. These solid-state LED lamps, rather than organic light emitting diode (OLED) or polymer light-emitting diode (PLED), have a number of advantages over conventional incandescent bulbs and halogen lamps, such as high efficiency to convert electrical energy into light, reliability and long operating lifetime. To meet with the further requirement of high color rendering index, warm light with low color temperature, high thermal stability and higher energy efficiency for WLEDs, new phosphors that can absorb excitation energy from blue or nUV LEDs and generate visible emissions efficiently are desired. The criteria of choosing the best phosphors, for blue (450−480 nm) and nUV (380−400 nm) LEDs, strongly depends on the absorption and emission of the phosphors. Moreover, the balance of light between the emission from blue-nUV LEDs and the emissions from phosphors (such as yellow from Y3Al5O12:Ce3+) is important to obtain white light with proper color rendering index and color temperature. Here, we will review the status of phosphors for LEDs and prospect the future development.

Radiation-induced defects in manganese-doped lithium tetraborate phosphor.

Science.gov (United States)

Annalakshmi, O; Jose, M T; Madhusoodanan, U; Sridevi, J; Venkatraman, B; Amarendra, G; Mandal, A B

2015-01-01

Lithium tetraborate doped with manganese synthesised by solid-state sintering technique exhibits a dosimetric peak at 280°C. The high-temperature glow curve results in no fading for three months. The sensitivity of Li2B4O7:Mn is determined to be 0.9 times that of TLD-100. The infrared spectrum of this phosphor indicates the presence of bond vibrations corresponding to BO4 tetrahedral and BO3 triangles. The mechanism for thermoluminescence in this phosphor was proposed based on the thermoluminescence (TL) emission spectra, kinetic analysis of TL glow curves and electron paramagnetic resonance (EPR) measurements on non-irradiated and gamma-irradiated phosphors. It was identified that oxygen vacancies and Boron oxygen hole centre (BOHC) are the electron and hole trap centres for TL in this phosphor. When the phosphor is heated, the electrons are released from the electron trap and recombine with the trapped holes. The excitation energy during the recombination is transferred to the nearby Mn(2+) ions, which emit light at 580 nm. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

New Silicate Phosphors for a White LED(Electronic Displays)

OpenAIRE

Toda, Kenji; Kawakami, Yoshitaka; Kousaka, Shin-ichiro; Ito, Yutaka; Komeno, Akira; Uematsu, Kazuyoshi; Sato, Mineo

2006-01-01

We focus on the development of new silicate phosphors for a white LED. In the europium doped silicate system, four LED phosphor candidates-Li_2SrSiO_4:Eu^, Ba_9Sc_2Si_6O_:Eu^, Ca_3Si_2O_7:Eu^ and Ba_2MgSi_2O_7:Eu^ were found. Luminescent properties under near UV and visible excitation were investigated for the new Eu^ doped LED silicate phosphors. These new phosphors have a relatively strong absorption band in a long wavelength region.

A novel red-emitting phosphor for white light-emitting diodes

International Nuclear Information System (INIS)

Ren, Fuqiang; Chen, Donghua

2010-01-01

A novel red-emitting phosphor of Eu 3+ -activated molybdate was prepared at 850 o C by a modified solid-state reaction. Photoluminescence (PL) results showed that the phosphor can be efficiently excited by UV-visible light from 350 to 550 nm, and exhibited bright red emission at 614 nm. XPS are taken to investigate the structure and compositions of this material. The crystallization and particle sizes of the phosphor have been investigated by using powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). TEM images show that the grain size of the phosphor is about 30 nm which is in full agreement with the theoretical calculation data from the XRD patterns.

Separation of rare earths from solutions of phosphoric acid

International Nuclear Information System (INIS)

Jones, E.A.

1977-01-01

Rare earths are separated from 6M phosphoric acid by adsorption onto cation resin BIORAD AG50W-X8. The phosphoric acid is then washed from the column, and the rare earths are eluted with 4M hydrochloric acid

Surface-Plasmon-Enhanced Emissions of Phosphors with Au Nanoparticles Embedded in ITO

Energy Technology Data Exchange (ETDEWEB)

Kim, Ja-Yeon [Korea Photonics Technology Institute (KOPTI), Gwangju (Korea, Republic of); Oh, Seung Jong; Park, Hyun-Sun; Kim, Min-Woo; Cho, Yoo-Hyun; Kwon, Min-Ki [Chosun University, Gwangju (Korea, Republic of)

2017-03-15

Au nanoparticles were embedded in a transparent conducting layer of indium tin oxide in order to evaluate the feasibility of applying a surface-plasmon (SP)-enhanced phosphor to light-emitting diodes (LEDs). The efficiency of the phosphor was improved by energy matching between the phosphor and the SP of the Au nanoparticles. After the density of the Au nanoparticles and the thickness of the spacer layer had been optimized, the efficiency of a green phosphor was improved by 64% compared to that of an isolated green phosphor. This work provides a way to fabricate high-efficiency LEDs with high color-rendering indices and wide color gamuts in white LEDs.

Ultraviolet /UV/ sensitive phosphors for silicon imaging detectors

Science.gov (United States)

Viehmann, W.; Cowens, M. W.; Butner, C. L.

1981-01-01

The fluorescence properties of UV sensitive organic phosphors and the radiometric properties of phosphor coated silicon detectors in the VUV, UV, and visible wavelengths are described. With evaporated films of coronene and liumogen, effective quantum efficiencies of up to 20% have been achieved on silicon photodiodes in the vacuum UV. With thin films of methylmethacrylate (acrylic), which are doped with organic laser dyes and deposited from solution, detector quantum efficiencies of the order of 15% for wavelengths of 120-165 nm and of 40% for wavelengths above 190 nm have been obtained. The phosphor coatings also act as antireflection coatings and thereby enhance the response of coated devices throughout the visible and near IR.

Phosphorous loads evaluation from soil

International Nuclear Information System (INIS)

Mezzanotte, V.

1996-01-01

With reference to the well known difficulty of quantifying non point phosphorous loads, as well as to their growing relative importance where point source leads decrease, a literature review has been carried out concerning soil export coefficients. On such basis, the values which seem to be the most appropriate for Italy have been estimated for different land use categories. The main mechanisms determining non point phosphorous load generation and the factors affecting their importance are also described. In the end, criteria for estimating the importance of non point sources in a basin are suggested to be used for deciding whether a traditional, parametric assessment (inevitably involving a certain error) can be acceptable or experimental measures are needed

Transcriptional regulation of Saccharomyces cerevisiaeCYS3 encoding cystathionine γ-lyase

Science.gov (United States)

Hiraishi, Hiroyuki; Miyake, Tsuyoshi

2008-01-01

In studying the regulation of GSH11, the structural gene of the high-affinity glutathione transporter (GSH-P1) in Saccharomyces cerevisiae, a cis-acting cysteine responsive element, CCGCCACAC (CCG motif), was detected. Like GSH-P1, the cystathionine γ-lyase encoded by CYS3 is induced by sulfur starvation and repressed by addition of cysteine to the growth medium. We detected a CCG motif (−311 to −303) and a CGC motif (CGCCACAC; −193 to −186), which is one base shorter than the CCG motif, in the 5′-upstream region of CYS3. One copy of the centromere determining element 1, CDE1 (TCACGTGA; −217 to −210), being responsible for regulation of the sulfate assimilation pathway genes, was also detected. We tested the roles of these three elements in the regulation of CYS3. Using a lacZ-reporter assay system, we found that the CCG/CGC motif is required for activation of CYS3, as well as for its repression by cysteine. In contrast, the CDE1 motif was responsible for only activation of CYS3. We also found that two transcription factors, Met4 and VDE, are responsible for activation of CYS3 through the CCG/CGC and CDE1 motifs. These observations suggest a dual regulation of CYS3 by factors that interact with the CDE1 motif and the CCG/CGC motifs. PMID:18317767

Analysis of phosphoric ore bacterial and eucaryal microbial diversity ...

African Journals Online (AJOL)

These findings provided new opportunities into phosphoric ore microbiology that could be useful in biological system removing waste gases generated from the phosphoric industry. Keywords: Microbial community, bacteria, archaea, eucarya, mining residue. African Journal of Biotechnology, Vol 13(30) 3023-3029 ...

Production and characterization of activated carbon using indigenous waste materials

International Nuclear Information System (INIS)

Shahid, M.; Ibrahim, F.

2011-01-01

Activated carbon was produced from shisham wood and coconut shell through chemical activation, using phosphoric acid and low temperature carbonization. Proximate analysis and characterization of the product were carried out and Brunauer Emmett Teller (BET) surface area, total ash content, moisture content, pH value and iodine number were determined. The product characteristics were well comparable with those of the commercially available activated carbon. (author)

Intravascular imaging with a storage phosphor detector

Energy Technology Data Exchange (ETDEWEB)

Shikhaliev, Polad M; Petrek, Peter; Matthews, Kenneth L II; Fritz, Shannon G [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA (United States); Bujenovic, L Steven [PET Imaging Center, Our Lady of the Lake Medical Center, Baton Rouge, LA (United States); Xu Tong, E-mail: pshikhal@lsu.ed [Department of Physics, Carleton University, Ottawa (Canada)

2010-05-21

The aim of this study is to develop and test an intravascular positron imaging system based on a storage phosphor detector for imaging and detecting vulnerable plaques of human coronary arteries. The radiotracer F18-FDG accumulates in vulnerable plaques with inflammation of the overlying cap. The vulnerable plaques can, therefore, be imaged by recording positrons emitted from F18-FDG with a detector inserted into the artery. A prototype intravascular detector was constructed based on storage phosphor. The detector uses a flexible storage phosphor tube with 55 mm length, 2 mm diameter and 0.28 mm wall thickness. The intravascular detector is guided into the vessel using x-ray fluoroscopy and the accumulated x-ray signal must be erased prior to positron imaging. For this purpose, a light diffuser, 0.9 mm in diameter and 55 mm in length, was inserted into the detector tube. The light diffuser was connected to a laser source through a 2 m long optical fiber. The diffuser redirected the 0.38 W laser light to the inner surface of the phosphor detector to erase it. A heart phantom with 300 cm{sup 3} volume and three coronary arteries with 3.2 mm diameter and with several plaques was constructed. FDG solution with 0.5 {mu}Ci cm{sup -3} activity concentration was filled in the heart and coronary arteries. The detector was inserted in a coronary artery and the signal from the plaques and surrounding background activity was recorded for 2 min. Then the phosphor detector was extracted and read out using a storage phosphor reader. The light diffuser erased the signal resulting from fluoroscopic exposure to level below that encountered during positron imaging. Vulnerable plaques with area activities higher than 1.2 nCi mm{sup -2} were visualized by the detector. This activity is a factor of 10-20 lower than that expected in human vulnerable plaques. The detector was able to image the internal surface of the coronary vessels with 50 mm length and 360{sup 0} circumference. Spatial

Development of BaSO sub 4 :Eu thermoluminescence phosphor

CERN Document Server

Madhusoodanan, U; Lakshmanan, A R

1999-01-01

A highly sensitive thermoluminescence (TL) phosphor based on BaSO sub 4 :Eu was developed following the coprecipitation technique and firing in argon atmosphere at 1123 K. Photoluminescence studies confirm that firing in argon atmosphere instead of air increased the incorporation of Eu ions in 2+ valence state. At low gamma-ray doses, its TL sensitivity is nearly 2 to 3 times higher than that of CaSO sub 4 :Dy phosphor. The other salient features of this BaSO sub 4 :Eu TL phosphor are a constant glow curve shape and a nearly linear gamma-ray dose response.

Normalization of stable isotope data for carbonate minerals: implementation of IUPAC guideline

Science.gov (United States)

Kim, Sang-Tae; Coplen, Tyler B.; Horita, Juske

2015-01-01

Carbonate minerals provide a rich source of geochemical information because their δ13C and δ18O values provide information about surface and subsurface Earth processes. However, a significant problem is that the same δ18O value is not reported for the identical carbonate sample when analyzed in different isotope laboratories in spite of the fact that the International Union of Pure and Applied Chemistry (IUPAC) has provided reporting guidelines for two decades. This issue arises because (1) the δ18O measurements are performed on CO2 evolved by reaction of carbonates with phosphoric acid, (2) the acid-liberated CO2 is isotopically fractionated (enriched in 18O) because it contains only two-thirds of the oxygen from the solid carbonate, (3) this oxygen isotopic fractionation factor is a function of mineralogy, temperature, concentration of the phosphoric acid, and δ18O value of water in the phosphoric acid, (4) researchers may use any one of an assortment of oxygen isotopic fractionation factors that have been published for various minerals at various reaction temperatures, and (5) it sometimes is not clear how one should calculate δ18OVPDB values on a scale normalized such that the δ18O value of SLAP reference water is −55.5 ‰ relative to VSMOW reference water.

Rare Earth Doped Lanthanum Calcium Borate Polycrystalline Red Phosphors

Directory of Open Access Journals (Sweden)

H. H. Xiong

2014-01-01

Full Text Available Single-phased Sm3+ doped lanthanum calcium borate (SmxLa2−xCaB10O19, SLCB, x=0.06 polycrystalline red phosphor was prepared by solid-state reaction method. The phosphor has two main excitation peaks located at 398.5 nm and 469.0 nm, which are nicely in accordance with the emitting wavelengths of commercial near-UV and blue light emitting diode chips. Under the excitation of 398.0 nm, the dominant red emission of Sm3+ in SLCB phosphor is centered at 598.0 nm corresponding to the transition of 4G5/2 → 6H7/2. The Eu3+ fluorescence in the red spectral region is applied as a spectroscopic probe to reveal the local site symmetry in the host lattice and, hence, Judd-Ofelt parameters Ωt  (t=2, 4 of Eu3+ in the phosphor matrix are derived to be 3.62×10-20 and 1.97×10-20 cm2, indicating a high asymmetrical and strong covalent environment around rare earth luminescence centers. Herein, the red phosphors are promising good candidates employed in white light emitting diodes (LEDs illumination.

Photoluminescence studies on holmium (III) and praseodymium (III) doped calcium borophosphate (CBP) phosphors

Science.gov (United States)

Reddy Prasad, V.; Damodaraiah, S.; Devara, S. N.; Ratnakaram, Y. C.

2018-05-01

Using solid state reaction method, Ho3+ and Pr3+ doped calcium borophosphate (CBP) phosphors were prepared. These phosphors were characterized using XRD, SEM, FT-IR, 31P solid state NMR, photoluminescence (PL) and decay profiles. Structural details were discussed from XRD and FT-IR spectra. From 31P NMR spectra of these phosphors, mono-phosphate complexes Q0-(PO43-) were observed. Photoluminescence spectra were measured for both Ho3+ and Pr3+ doped calcium borophosphate phosphors and the spectra were studied for different concentrations. Decay curves were obtained for the excited level, 5F4+5S2 of Ho3+ and 1D2 level of Pr3+ in these calcium borophosphate phosphors and lifetimes were measured. CIE color chromaticity diagrams are drawn for these two rare earth ions in calcium borophosphate phosphors. Results show that Ho3+ and Pr3+ doped CBP phosphors might be served as green and red luminescence materials.

Preparation of red phosphor (Y, Gd)BO3:Eu by soft chemistry methods

International Nuclear Information System (INIS)

Cui Xiangzhong; Zhuang Weidong; Yu Zhijian; Xia Tian; Huang Xiaowei; Li Hongwei

2008-01-01

The three soft chemistry methods were employed to prepare the red phosphor (Y, Gd)BO 3 :Eu, such as coprecipitation-combustion method, salt assisted combustion method and emulsion method. The main factors affecting particle size, particle distribution and luminescent properties of the product were investigated in detail, and as a result, the preparation processes were optimized. The phosphors were characterized by X-ray diffraction (XRD), scanning electronic microscope (SEM), transmission electronic microscope (TEM) and vacuum ultraviolet (VUV) spectra. Results reveal that phosphors with different morphology, small particle size and high luminescence intensity could be obtained by soft chemistry methods. The difference between the luminescence properties of phosphors in this work and commercial rare earth borate phosphor is discussed. The phosphor with grain shape and high luminescence intensity could be prepared by coprecipitation-combustion method, nanophosphor could be prepared by salt assisted combustion method, and spherical phosphor with a narrow size distribution could be obtained by using emulsion method

World wide IFC phosphoric acid fuel cell implementation

Energy Technology Data Exchange (ETDEWEB)

King, J.M. Jr

1996-04-01

International Fuel Cells, a subsidary of United technologies Corporation, is engaged in research and development of all types of fuel cell technologies and currently manufactures alkaline fuel cell power plants for the U.S. manned space flight program and natural gas fueled stationary power plants using phosphoric acid fuel cells. This paper describes the phosphoric acid fuel cell power plants.

One Year Experience of Pheburane® (Sodium Phenylbutyrate) Treatment in a Patient with Argininosuccinate Lyase Deficiency

OpenAIRE

Uçar, Sema Kalkan; Ozbaran, Burcu; Altinok, Yasemin Atik; Kose, Melis; Canda, Ebru; Kagnici, Mehtap; Coker, Mahmut

2015-01-01

Argininosuccinate lyase deficiency (ASLD) is a urea cycle disorder (UCD) treated with dietary adjustment and nitrogen scavenging agents. “Pheburane®” is a new tasteless and odour-free formulation of sodium phenylbutyrate, indicated in the treatment of UCD.

Kenya's Climate Change Action Plan. Low Carbon Climate Resilient Development Pathway

Energy Technology Data Exchange (ETDEWEB)

Murphy, D.; Sawyer, D.; Stiebert, S.; McFatridge, S. [International Institute for Sustainable Development IISD, Winnipeg, Manitoba (Canada); Wuertenberger, L.; Van Tilburg, X.; Hekkenberg, M. [Energy research Centre of the Netherlands ECN, Policy Studies, Amsterdam (Netherlands); Owino, T.; Battye, W. [ClimateCare, Nairobi (Kenya); Mutia, T. [Regional Institute for Social Enterprise Kenya RISE, Nairobi (Kenya); Olum, P. [Climate Change Consultant (Kenya)

2012-12-15

Kenya Vision 2030 - the long-term development blueprint for the country - aims to transform Kenya into 'a newly industrialising, middle-income country providing a high quality of life to all its citizens in a clean and secure environment'. A low carbon climate resilient development pathway, as set out in this Climate Change Action Plan, can help meet Vision 2030 goals through actions that address both sustainable development and climate change. This pathway can also help the Government achieve the Millennium Development Goals and other internationally agreed development goals without compromising the environment and its natural resources. As Kenya realizes its development aspirations, there will be gains and risks. A growing population and economy with migration to cities will mean increases in greenhouse gas (GHG) emissions. Resulting environmental and social conditions, including increased competition over resources, could intensify vulnerability to climate risks. Transitioning to a low carbon climate resilient development pathway can address future risks thereby improving Kenya's ability to prosper under a changing climate while reducing the emissions intensity of a growing economy. Moving forward on the 2010 National Climate Change Response Strategy will help Kenya transition to a low carbon climate resilient development pathway that puts people and livelihoods at the forefront. The strategy recognized the importance of climate change and development, and this Climate Change Action Plan is the logical next step. A yearlong multistakeholder participatory process involving the public sector, private sector and civil society resulted in this Action Plan that identifies priority climate change actions for Kenya for the short, medium and long term. The Government of Kenya takes climate change and its impact on development seriously. Climate change is considered a crosscutting issue that will be mainstreamed in the planning process both at the national

Initiation in the study of uranium recovery from the phosphoric acid

Energy Technology Data Exchange (ETDEWEB)

Anchondo Adalid, J M

1974-01-01

The loss of considerable amounts of uranium in the Mexican phosphoric acid industry makes it important to study economic methods of recovery; the studies can serve as a basis for the construction and operation of a pilot plant as a normal preliminary to larger-scale projects. Routine experimental techniques for solvent extraction were employed. Extraction efficiencies of the order of 90-95% were obtained using 0.09-0.18M solutions of a mixture of phosphoric octyl esters applied to 4 and 6M solutions of phosphoric acid (reagent grade) containing uranium in concentrations of 0.05-0.50g of U/sub 3/O/sub 8/ per litre of acid. The conclusion was reached that phosphoric octyl esters can be used for recovering uranium in satisfactory quantities from phosphoric acid solutions by means of solvent extraction, and that the uranium can be separated from the solvent by the established procedures.

Initiation in the study of uranium recovery from the phosphoric acid

International Nuclear Information System (INIS)

Anchondo Adalid, J.M.

1974-01-01

The loss of considerable amounts of uranium in the Mexican phosphoric acid industry makes it important to study economic methods of recovery; the studies can serve as a basis for the construction and operation of a pilot plant as a normal preliminary to larger-scale projects. Routine experimental techniques for solvent extraction were employed. Extraction efficiencies of the order of 90-95% were obtained using 0.09-0.18M solutions of a mixture of phosphoric octyl esters applied to 4 and 6M solutions of phosphoric acid (reagent grade) containing uranium in concentrations of 0.05-0.50g of U 3 O 8 per litre of acid. The conclusion was reached that phosphoric octyl esters can be used for recovering uranium in satisfactory quantities from phosphoric acid solutions by means of solvent extraction, and that the uranium can be separated from the solvent by the established procedures. (author)

Method for the recovery of uranium from a concentrate using pure phosphoric acid

International Nuclear Information System (INIS)

1980-01-01

Procedure for the recovery of an uranium bearing concentrate and pure phosphoric acid from a wet process phosphoric acid from the treatment fluid with a precipitation means in conjunction with an organic diluent, the thus formed precipitate to separate and from the remaining mixture of phosphoric acid and diluent the phosphoric acid to extract, characterised in that one applies an inorganic fluorine compound. (G.C.)

Phosphorus poisoning of molybdenum sulfide hydrodesulfurization catalysts supported on carbon and alumina

NARCIS (Netherlands)

Bouwens, S.M.A.M.; Vissers, J.P.R.; Beer, de V.H.J.; Prins, R.

1988-01-01

Phosphorus-containing Mo sulfide catalysts supported on ¿-Al2O3 and activated carbon were evaluated for their thiophene HDS activities. Phosphorus was added as phosphoric acid to the carrier material prior to the molybdenum component. The thiophene HDS activity of the carbon-supported catalysts was

Organic Acids: The Pools of Fixed Carbon Involved in Redox Regulation and Energy Balance in Higher Plants

Directory of Open Access Journals (Sweden)

Abir U Igamberdiev

2016-07-01

Full Text Available Organic acids are synthesized in plants as a result of the incomplete oxidation of photosynthetic products and represent the stored pools of fixed carbon accumulated due to different transient times of conversion of carbon compounds in metabolic pathways. When redox level in the cell increases, e.g., in conditions of active photosynthesis, the tricarboxylic acid (TCA cycle in mitochondria is transformed to a partial cycle supplying citrate for the synthesis of 2-oxoglutarate and glutamate (citrate valve, while malate is accumulated and participates in the redox balance in different cell compartments (via malate valve. This results in malate and citrate frequently being the most accumulated acids in plants. However, the intensity of reactions linked to the conversion of these compounds can cause preferential accumulation of other organic acids, e.g., fumarate or isocitrate, in higher concentrations than malate and citrate. The secondary reactions, associated with the central metabolic pathways, in particularly with the TCA cycle, result in accumulation of other organic acids that are derived from the intermediates of the cycle. They form the additional pools of fixed carbon and stabilize the TCA cycle. Trans-aconitate is formed from citrate or cis-aconitate, accumulation of hydroxycitrate can be linked to metabolism of 2-oxoglutarate, while 4-hydroxy-2-oxoglutarate can be formed from pyruvate and glyoxylate. Glyoxylate, a product of either glycolate oxidase or isocitrate lyase, can be converted to oxalate. Malonate is accumulated at high concentrations in legume plants. Organic acids play a role in plants in providing redox equilibrium, supporting ionic gradients on membranes, and acidification of the extracellular medium.

Phosphates and phosphoric acid

Energy Technology Data Exchange (ETDEWEB)

Becker, P [Compagnie Francaise de l' Azote, Paris (France)

1983-01-01

In chapter 8.5 the following aspects of uranium recovery are treated: basis of extraction process, extraction principle, solvents, strength of the acid to be treated, technology, main processes in use, impact of uranium recovery on phosphoric acid plants, and economics of uranium recovery plants.

Multifunctional Poly(2,5-benzimidazole)/Carbon Nanotube Composite Films

Science.gov (United States)

2010-01-01

Multifunctional Poly(2,5- benzimidazole )/Carbon Nanotube Composite Films JI-YE KANG,1 SOO-MI EO,1 IN-YUP JEON,1 YEONG SUK CHOI,2 LOON-SENG TAN,3 JONG...molecular-weight poly(2,5- benzimidazole ) (ABPBI). ABPBI/carbon nanotube (CNT) compo- sites were prepared via in situ polymerization of the AB-monomer in the...polymerization; multiwalled carbon nanotube (MWCNT); nano- composites; poly(2,5- benzimidazole ); (ABPBI); polycondensa- tion; poly(phosphoric acid); single-walled

Carbon isotope fractionation by sulfate-reducing bacteria using different pathways for the oxidation of acetate.

Science.gov (United States)

Goevert, Dennis; Conrad, Ralf

2008-11-01

Acetate is a key intermediate in the anaerobic degradation of organic matter. In anoxic environments, available acetate is a competitive substrate for sulfate-reducing bacteria (SRB) and methane-producing archaea. Little is known about the fractionation of carbon isotopes by sulfate reducers. Therefore, we determined carbon isotope compositions in cultures of three acetate-utilizing SRB, Desulfobacter postgatei, Desulfobacter hydrogenophilus, and Desulfobacca acetoxidans. We found that these species showed strong differences in their isotope enrichment factors (epsilon) of acetate. During the consumption of acetate and sulfate, acetate was enriched in 13C by 19.3% per hundred in Desulfobacca acetoxidans. By contrast, both D. postgatei and D. hydrogenophilus showed a slight depletion of 13C resulting in epsilon(ac)-values of 1.8 and 1.5% per hundred, respectively. We suggest that the different isotope fractionation is due to the different metabolic pathways for acetate oxidation. The strongly fractionating Desulfobacca acetoxidans uses the acetyl-CoA/carbon monoxide dehydrogenase pathway, which is also used by acetoclastic methanogens that show a similar fractionation of acetate (epsilon(ac) = -21 to -27% per hundred). In contrast, Desulfobacter spp. oxidize acetate to CO2 via the tricarboxylic acid (TCA) cycle and apparently did not discriminate against 13C. Our results suggestthat carbon isotope fractionation in environments with sulfate reduction will strongly depend on the composition of the sulfate-reducing bacterial community oxidizing acetate.

Chronic aspartame intake causes changes in the trans-sulphuration pathway, glutathione depletion and liver damage in mice

Directory of Open Access Journals (Sweden)

Isabela Finamor

2017-04-01

Full Text Available No-caloric sweeteners, such as aspartame, are widely used in various food and beverages to prevent the increasing rates of obesity and diabetes mellitus, acting as tools in helping control caloric intake. Aspartame is metabolized to phenylalanine, aspartic acid, and methanol. Our aim was to study the effect of chronic administration of aspartame on glutathione redox status and on the trans-sulphuration pathway in mouse liver. Mice were divided into three groups: control; treated daily with aspartame for 90 days; and treated with aspartame plus N-acetylcysteine (NAC. Chronic administration of aspartame increased plasma alanine aminotransferase (ALT and aspartate aminotransferase activities and caused liver injury as well as marked decreased hepatic levels of reduced glutathione (GSH, oxidized glutathione (GSSG, γ-glutamylcysteine ​​(γ-GC, and most metabolites of the trans-sulphuration pathway, such as cysteine, S-adenosylmethionine (SAM, and S-adenosylhomocysteine ​​(SAH. Aspartame also triggered a decrease in mRNA and protein levels of the catalytic subunit of glutamate cysteine ligase (GCLc and cystathionine γ-lyase, and in protein levels of methionine adenosyltransferase 1A and 2A. N-acetylcysteine prevented the aspartame-induced liver injury and the increase in plasma ALT activity as well as the decrease in GSH, γ-GC, cysteine, SAM and SAH levels and GCLc protein levels. In conclusion, chronic administration of aspartame caused marked hepatic GSH depletion, which should be ascribed to GCLc down-regulation and decreased cysteine levels. Aspartame triggered blockade of the trans-sulphuration pathway at two steps, cystathionine γ-lyase and methionine adenosyltransferases. NAC restored glutathione levels as well as the impairment of the trans-sulphuration pathway.

Chronic aspartame intake causes changes in the trans-sulphuration pathway, glutathione depletion and liver damage in mice.

Science.gov (United States)

Finamor, Isabela; Pérez, Salvador; Bressan, Caroline A; Brenner, Carlos E; Rius-Pérez, Sergio; Brittes, Patricia C; Cheiran, Gabriele; Rocha, Maria I; da Veiga, Marcelo; Sastre, Juan; Pavanato, Maria A

2017-04-01

No-caloric sweeteners, such as aspartame, are widely used in various food and beverages to prevent the increasing rates of obesity and diabetes mellitus, acting as tools in helping control caloric intake. Aspartame is metabolized to phenylalanine, aspartic acid, and methanol. Our aim was to study the effect of chronic administration of aspartame on glutathione redox status and on the trans-sulphuration pathway in mouse liver. Mice were divided into three groups: control; treated daily with aspartame for 90 days; and treated with aspartame plus N-acetylcysteine (NAC). Chronic administration of aspartame increased plasma alanine aminotransferase (ALT) and aspartate aminotransferase activities and caused liver injury as well as marked decreased hepatic levels of reduced glutathione (GSH), oxidized glutathione (GSSG), γ-glutamylcysteine ​​(γ-GC), and most metabolites of the trans-sulphuration pathway, such as cysteine, S-adenosylmethionine (SAM), and S-adenosylhomocysteine ​​(SAH). Aspartame also triggered a decrease in mRNA and protein levels of the catalytic subunit of glutamate cysteine ligase (GCLc) and cystathionine γ-lyase, and in protein levels of methionine adenosyltransferase 1A and 2A. N-acetylcysteine prevented the aspartame-induced liver injury and the increase in plasma ALT activity as well as the decrease in GSH, γ-GC, cysteine, SAM and SAH levels and GCLc protein levels. In conclusion, chronic administration of aspartame caused marked hepatic GSH depletion, which should be ascribed to GCLc down-regulation and decreased cysteine levels. Aspartame triggered blockade of the trans-sulphuration pathway at two steps, cystathionine γ-lyase and methionine adenosyltransferases. NAC restored glutathione levels as well as the impairment of the trans-sulphuration pathway. Copyright © 2017. Published by Elsevier B.V.

Investigating Pathways of Nutrient and Energy Flows Through Aquatic Food Webs Using Stable Isotopes of Carbon and Nitrogen

Energy Technology Data Exchange (ETDEWEB)

Hadwen, W. L.; Bunn, S. E. [Australian Rivers Institute, Griffith School of Environment, Griffith University, Nathan Campus, Brisbane, Queensland (Australia)

2013-05-15

Carbon and nitrogen stable isotopes can provide valuable insights into pathways of nutrient and energy flows in aquatic ecosystems. Carbon stable isotopes are principally used to trace pathways of organic matter transfer through aquatic food webs, particularly with regard to identifying the dominant sources of nutrition for aquatic biota. Stable isotopes of carbon have been widely used to answer one of the most pressing questions in aquatic food web ecology - to what degree do in-stream (autochthonous) and riparian (allochthonous) sources of energy fuel riverine food webs? In conjunction with carbon stable isotopes, nitrogen stable isotopes have been used to determine the trophic position of consumers and to identify the number of trophic levels in aquatic food webs. More recently, stable nitrogen isotopes have been recommended as indicators of anthropogenic disturbances. Specifically, agricultural land uses and/or sewage effluent discharge have been shown to significantly increase {delta}{sup 15}N signatures in primary producers and higher order consumers in freshwater, estuarine and marine environments. Together, carbon and nitrogen stable isotopes can be used to examine natural food web functions as well as the degree to which human modifications to catchments and aquatic environments can influence aquatic ecosystem function. (author)

Contributions of citrate in redox potential maintenance and ATP production: metabolic pathways and their regulation in Lactobacillus panis PM1.

Science.gov (United States)

Kang, Tae Sun; Korber, Darren R; Tanaka, Takuji

2013-10-01

Lactobacillus panis PM1 belongs to the group III heterofermentative lactobacilli and can utilize various NADH-reoxidizing routes (e.g., citrate, glycerol, and oxygen) according to environmental conditions. In this study, we investigated the ability of L. panis PM1 to produce succinate, acetate, and lactate via citrate utilization. Possible pathways, as well as regulation, for citrate metabolism were examined on the basis of the genome sequence data and metabolic profiles of L. panis PM1. The presence of citrate led to the up-regulation, at the transcriptional level, of the genes encoding for citrate lyase, malate dehydrogenase, and malic enzyme of the citrate pathways by 10- to 120-fold. The transcriptional regulator of the dha operon coding for glycerol dehydratase of L. panis PM1 repressed the expression of the citrate lyase gene (10-fold). Metabolite analyses indicated that the transcriptional enhancement by citrate stimulated succinate yield. Citrate metabolism contributed to energy production by providing a major alternate pathway for NAD(+) regeneration and allowed acetyl phosphate to yield acetate/ATP instead of ethanol/NAD(+). Additionally, a branching pathway from oxaloacetate to pyruvate increased the pool of lactate, which was then used to produce ATP during stationary phase. However, the redirection of NADH-to-citrate utilization resulted in stress caused by end-products (i.e., succinate and acetate). This stress reduced succinate production by up to 50 % but did not cause significant changes at transcriptional level. Overall, citrate utilization was beneficial for the growth of L. panis PM1 by providing a NAD(+) regeneration route and producing extra ATP.

TL dosimetric characterization of gamma irradiated SrSO{sub 4}:Eu phosphors

Energy Technology Data Exchange (ETDEWEB)

Jayasudha, S., E-mail: jsnair.india@gmail.com [Mahatma Gandhi College, Kesavadasapuram, Pattom Palace P.O., Thiruvananthapuram 695004 (India); Madhukumar, K.; Nair, C.M.K.; Nair, Resmi G. [Mahatma Gandhi College, Kesavadasapuram, Pattom Palace P.O., Thiruvananthapuram 695004 (India); Rajesh, S. [Department of Materials & Ceramic Engineering, University of Aveiro, Aveiro 3810-193 (Portugal); Elias, T.S. [State Institute of Cancer Research, Medical College P.O., Thiruvananthapuram 695011 (India); Anandakumar, V.M. [Mahatma Gandhi College, Kesavadasapuram, Pattom Palace P.O., Thiruvananthapuram 695004 (India); State Institute of Cancer Research, Medical College P.O., Thiruvananthapuram 695011 (India); Department of Materials & Ceramic Engineering, University of Aveiro, Aveiro 3810-193 (Portugal); Gopakumar, N. [Mahatma Gandhi College, Kesavadasapuram, Pattom Palace P.O., Thiruvananthapuram 695004 (India)

2017-03-15

Thermoluminescence (TL) characteristics of SrSO{sub 4}:Eu nanostructured phosphor under gamma excitation has been studied and their suitability for environmental radiation dosimetry applications is discussed. The dopant level is tuned for optimum TL response. The effect of radiation dose and heating rate were investigated. The phosphor preserves linearity in the low dose region, 0.1 Gy to 20 Gy. PL studies of irradiated and un-irradiated phosphors reveal that the dopant Eu exists in divalent state and are the luminescence emission centres in the material. The fading properties of SrSO{sub 4}:Eu phosphor are observed to be better than that of the commercial dosimeters TLD-200 and TLD-400. The kinetic parameters are calculated using Chen's method and initial rise method and verified by Computerized Glow curve Deconvolution (CGCD). The sensitivity of the synthesized phosphor is found to be very high when compared with that of the commercial standard dosimeter CaSO{sub 4}:Dy. The phosphor is found to be stable for short term radiation monitoring.

Benzoic acid fermentation from starch and cellulose via a plant-like β-oxidation pathway in Streptomyces maritimus

Directory of Open Access Journals (Sweden)

Noda Shuhei

2012-04-01

Full Text Available Abstract Background Benzoic acid is one of the most useful aromatic compounds. Despite its versatility and simple structure, benzoic acid production using microbes has not been reported previously. Streptomyces are aerobic, Gram-positive, mycelia-forming soil bacteria, and are known to produce various kinds of antibiotics composed of many aromatic residues. S. maritimus possess a complex amino acid modification pathway and can serve as a new platform microbe to produce aromatic building-block compounds. In this study, we carried out benzoate fermentation using S. maritimus. In order to enhance benzoate productivity using cellulose as the carbon source, we constructed endo-glucanase secreting S. maritimus. Results After 4 days of cultivation using glucose, cellobiose, or starch as a carbon source, the maximal level of benzoate reached 257, 337, and 460 mg/l, respectively. S. maritimus expressed β-glucosidase and high amylase-retaining activity compared to those of S. lividans and S. coelicolor. In addition, for effective benzoate production from cellulosic materials, we constructed endo-glucanase-secreting S. maritimus. This transformant efficiently degraded the phosphoric acid swollen cellulose (PASC and then produced 125 mg/l benzoate. Conclusions Wild-type S. maritimus produce benzoate via a plant-like β-oxidation pathway and can assimilate various carbon sources for benzoate production. In order to encourage cellulose degradation and improve benzoate productivity from cellulose, we constructed endo-glucanase-secreting S. maritimus. Using this transformant, we also demonstrated the direct fermentation of benzoate from cellulose. To achieve further benzoate productivity, the L-phenylalanine availability needs to be improved in future.

A novel KMgPO{sub 4}:Tb{sup 3+}(KMPT) phosphor for radiation dosimetry

Energy Technology Data Exchange (ETDEWEB)

Palan, C.B., E-mail: chetanpalan27@gmail.com [Department of Physics, Sant Gadge Baba Amravati University, Amravati 44602 (India); Bajaj, N.S. [Department of Physics, Toshniwal ACS College, Sengaon, Hingoli 431542 (India); Soni, A. [Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Mumbai 400094 (India); Omanwar, S.K. [Department of Physics, Sant Gadge Baba Amravati University, Amravati 44602 (India)

2016-08-15

The polycrystalline sample of KMgPO{sub 4}:Tb{sup 3+}(KMPT) phosphor was successfully synthesized by using solid state method. The X-ray powder diffraction, photoluminescence (PL) emission and excitation spectra, thermoluminescence (TL) and optically stimulated luminescence (OSL) were thoroughly measured. The PL spectra of as-prepared KMPT phosphor showed characteristic blue-green emission, when excited by 226 nm under UV excitation. The optimum PL intensity was observed at 0.01 mol concentration of Tb{sup 3+}ions and this phosphor used for remaining studies. The TL glow curve of KMPT phosphor consist two characterized peaks, which were deconvoluted and the kinetic parameters i.e. trap depth or activation energy, order of kinetic and frequency factor determined by using peak shape method. TL sensitivity of KMPT phosphors was found to be 10% than that of TL sensitivity of TLD-500 phosphor. The OSL sensitivity of KMPT was 0.92 times than OSL sensitivity of α-Al{sub 2}O{sub 3}:C phosphor. The OSL decay curve KMPT phosphor consist of three component having photoionization cross sections were found to be 0.26548×10{sup −17}, 0.220×10{sup −17}, 2.92×10{sup −17} cm{sup 2}. The KMPT phosphor showed linear dose response in range 100–6000 mGy and fading of KMPT phosphor was found to be 31% in 15 days. The Minimum detectable dose (MDD) was found to be 0.39 mGy with corresponding 3σ back ground. The phosphor shows good dosimetry properties such as sensitivity, dose response, MDD, Fading.

Carbon isotopic patterns of amino acids associated with various microbial metabolic pathways and physiological conditions

Science.gov (United States)

Wang, P. L.; Hsiao, K. T.; Lin, L. H.

2017-12-01

Amino acids represent one of the most important categories of biomolecule. Their abundance and isotopic patterns have been broadly used to address issues related to biochemical processes and elemental cycling in natural environments. Previous studies have shown that various carbon assimilative pathways of microorganisms (e.g. autotrophy, heterotrophy and acetotrophy) could be distinguished by carbon isotopic patterns of amino acids. However, the taxonomic and catabolic coverage are limited in previous examination. This study aims to uncover the carbon isotopic patterns of amino acids for microorganisms remaining uncharacterized but bearing biogeochemical and ecological significance in anoxic environments. To fulfill the purpose, two anaerobic strains were isolated from riverine wetland and mud volcano in Taiwan. One strain is a sulfate reducing bacterium (related to Desulfovibrio marrakechensis), which is capable of utilizing either H2 or lactate, and the other is a methanogen (related to Methanolobus profundi), which grows solely with methyl-group compounds. Carbon isotope analyses of amino acids were performed on cells grown in exponential and stationary phase. The isotopic patterns were similar for all examined cultures, showing successive 13C depletion along synthetic pathways. No significant difference was observed for the methanogen and lactate-utilizing sulfate reducer harvested in exponential and stationary phases. In contrast, the H2-utilizing sulfate reducer harvested in stationary phase depleted and enriched 13C in aspartic acid and glycine, respectively when compared with that harvested in exponential phase. Such variations might infer the change of carbon flux during synthesis of these two amino acids in the reverse TCA cycle. In addition, the discriminant function analysis for all available data from culture studies further attests the capability of using carbon isotope patterns of amino acids in identifying microbial metabolisms.

Regulation of a phenylalanine ammonia lyase (BbPAL) by calmodulin in response to environmental changes in the entomopathogenic fungus Beauveria bassiana.

Science.gov (United States)

Kim, Jiyoung; Park, Hyesung; Han, Jae-Gu; Oh, Junsang; Choi, Hyung-Kyoon; Kim, Seong Hwan; Sung, Gi-Ho

2015-11-01

Phenylalanine ammonia lyase (PAL, E.C. 4.3.1.5) catalyses the deamination of L -phenylalanine to trans-cinnamic acid and ammonia, facilitating a critical step in the phenylpropanoid pathway that produces a variety of secondary metabolites. In this study, we isolated BbPAL gene in the entomopathogenic fungus Beauveria bassiana. According to multiple sequence alignment, homology modelling and in vitro PAL activity, we demonstrated that BbPAL acts as a typical PAL enzyme in B. bassiana. BbPAL interacted with calmodulin (CaM) in vitro and in vivo, indicating that BbPAL is a novel CaM-binding protein. The functional role of CaM in BbPAL action was to negatively regulate the BbPAL activity in B. bassiana. High-performance liquid chromatography analysis revealed that L -phenylalanine was reduced and trans-cinnamic acid was increased in response to the CaM inhibitor W-7. Dark conditions suppressed BbPAL activity in B. bassiana, compared with light. In addition, heat and cold stresses inhibited BbPAL activity in B. bassiana. Interestingly, these negative effects of BbPAL activity by dark, heat and cold conditions were recovered by W-7 treatment, suggesting that the inhibitory mechanism is mediated through stimulation of CaM activity. Therefore, this work suggests that BbPAL plays a role in the phenylpropanoid pathway mediated by environmental stimuli via the CaM signalling pathway. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

Engineering Escherichia coli to grow constitutively on D-xylose using the carbon-efficient Weimberg pathway

Science.gov (United States)

Rossoni, Luca; Carr, Reuben; Baxter, Scott; Cortis, Roxann; Thorpe, Thomas; Eastham, Graham; Stephens, Gill

2018-01-01

Bio-production of fuels and chemicals from lignocellulosic C5 sugars usually requires the use of the pentose phosphate pathway (PPP) to produce pyruvate. Unfortunately, the oxidation of pyruvate to acetyl-coenzyme A results in the loss of 33 % of the carbon as CO2, to the detriment of sustainability and process economics. To improve atom efficiency, we engineered Escherichia coli to utilize d-xylose constitutively using the Weimberg pathway, to allow direct production of 2-oxoglutarate without CO2 loss. After confirming enzyme expression in vitro, the pathway expression was optimized in vivo using a combinatorial approach, by screening a range of constitutive promoters whilst systematically varying the gene order. A PPP-deficient (ΔxylAB), 2-oxoglutarate auxotroph (Δicd) was used as the host strain, so that growth on d-xylose depended on the expression of the Weimberg pathway, and variants expressing Caulobacter crescentus xylXAB could be selected on minimal agar plates. The strains were isolated and high-throughput measurement of the growth rates on d-xylose was used to identify the fastest growing variant. This strain contained the pL promoter, with C. crescentus xylA at the first position in the synthetic operon, and grew at 42 % of the rate on d-xylose compared to wild-type E. coli using the PPP. Remarkably, the biomass yield was improved by 53.5 % compared with the wild-type upon restoration of icd activity. Therefore, the strain grows efficiently and constitutively on d-xylose, and offers great potential for use as a new host strain to engineer carbon-efficient production of fuels and chemicals via the Weimberg pathway. PMID:29458683

Thermoluminescence dosimetric characteristics of thulium doped ZnB2O4 phosphor

International Nuclear Information System (INIS)

Annalakshmi, O.; Jose, M.T.; Madhusoodanan, U.; Subramanian, J.; Venkatraman, B.; Amarendra, G.; Mandal, A.B.

2014-01-01

Polycrystalline powder samples of rare earth doped Zinc borates were synthesized by high temperature solid state diffusion technique. Dosimetric characteristics of the phosphor like thermoluminescence glow curve, TL emission spectra, dose–response, fading studies, reproducibility and reusability studies were carried out on the synthesized phosphors. Among the different rare earth doped phosphors, thulium doped zinc borate was found to have a higher sensitivity. Hence detailed dosimetric characteristics of this phosphor were carried out. It is observed that the dose–response is linear from 10 mGy to 10 3 Gy in this phosphor. EPR measurements were carried out on unirradiated, gamma irradiated and annealed phosphors to identify the defect centers responsible for thermoluminescence. A TL model is proposed based on the EPR studies in these materials. Kinetic parameters were evaluated for the dosimetric peaks using various methods. The experimental results show that this phosphor can have potential applications in radiation dosimetry applications. -- Highlights: • Polycrystalline powder samples of rare earth doped zinc borates were synthesized. • Thulium was observed to be the most efficient dopant in ZnB 2 O 4 lattice. • TL intensity of the dosimetric peak is around 20 times that of TLD-100. • Based on EPR studies a TL mechanism is proposed in zinc borate. • Deconvolution of the glow curve carried out

Phosphor plate mammography: contrast studies and clinical experience

International Nuclear Information System (INIS)

Chang, C.H.J.; Martin, N.L.; Templeton, A.W.; Cook, L.T.; Harrison, L.A.; McFadden, M.A.; Dwyer, S.J. III; Spicer, J.; Crystal, J.M.

1992-01-01

Mammography and accurate microcalcification detection require very good spatial resolution. We have compared the diagnostic capabilities of reduced-exposure, third-generation, 5 cycles/mm computed radiography (CR) phosphor plates with conventional screen-film in 67 patients. No difference in diagnostic accuracy was detected. The digital characteristics of storage phosphor plates erabled us to study the relationship between contrast and spatial resolution. We developed a computer program to identify a single 100 μm pixel in a digital image and assign various gray levels to that pixel. Using this model, we determined that, for our 5 cycles/mm CR system, the imaged contrast of a 100 μm object was 62% of the original contrast. Current 5 cycles/mm phosphor plate systems cannot adequately detect microcalcifications that approximate 100 μm or smaller unless a magnification technique is used. (orig.)

Persistent phosphors for painting, medical and biological applications

International Nuclear Information System (INIS)

Nazarov, M.

2013-01-01

Multiphase micro and nanoparticle persistent phosphors are synthesized and applied for different fields including painting, medical and biological investigations. A lot of examples show a broad range of applications of persistent luminescence from bulk materials to high tech products, especially in medicine. The development of high efficiency nanosized phosphor makes it possible to propose persistent materials as very good candidates for photodynamic therapy of cancer. An artificial block from slag, concrete, and sand covered with SrAl 2 O 4 :Eu 2+ , Dy 3+ based phosphor is prepared, and a new direction in biology for algae cultivation and artificial reef is discussed. For the first time, underwater luminescence is experimentally studied under real sea conditions. Bright blue-green long-lasting afterglow is registered at a depth of 5 m. The fishes are attracted by the light of the artificial reef. (author)

Measurement of thermal neutron fluence with CaSO4 thermoluminescent phosphors

International Nuclear Information System (INIS)

Liu Jinhua; Su Jingling; Wei Zemin

1984-01-01

During neutron irradiation, some TL phosphors were activated. After leaving the irradiation field the TL phosphor produced self-irradiation. The TL output of self-dose was only related to the original neutron fluence and independent of the γ-radiation. Several CaSO 4 TL phosphors were made. They were CaSO 4 :Dy, CaSO 4 :Dy-Teflon, CaSO 4 :Dy mixed with Dy 2 O 3 , CaSO 4 :Mn mixed with Dy 2 O 3 . The linearity, and lower detection limits of these TL phosphors were measured. The thermal neutron response of CaSO 4 :Mn mixed with Dy 2 O 3 was 64 R/(10 10 cm -2 ) and the lower detection limit was 1.3x10 5 cm -2

A novel orange emissive phosphor SrWO4:Sm3+ for white light-emitting diodes

International Nuclear Information System (INIS)

Ju Zhenghua; Wei Ruiping; Ma Jingxin; Pang Chaoran; Liu Weisheng

2010-01-01

Research highlights: → A novel orange emissive phosphor SrWO 4 :Sm 3+ was firstly reported. → The optics properties of Sm 3+ -doped SrWO 4 phosphor were successfully discussed. → The temperature-dependent luminescence indicates the phosphor exhibits a small thermal-quenching property. → The phosphor is a potential candidate as orange-emitting component for white LED. - Abstract: A novel orange emissive phosphor, Sm 3+ -doped SrWO 4 , was synthesized by high temperature solid-state reaction in air atmosphere. The excitation spectra show that the phosphors can be efficiently excited by ultraviolet and near-ultraviolet light, the optimized concentration is 4 mol%. Three emission peaks locate at 562, 596 and 642 nm, corresponding to CIE chromaticity coordinates of (x = 0.54, y = 0.46), which indicates the orange light emitting. The decay curves are well fitted with triple-exponential decay models. The quantum yield of the Sr 0.96 Sm 0.04 WO 4 phosphor is about 70.65% under excitation of 377 nm. Furthermore, the temperature-dependent luminescence indicates the phosphor exhibits a small thermal-quenching property. So the phosphor is able to be applied to UV-LED chip-based white light-emitting diodes.

Mode of action of pectin lyase A of Aspergillus niger on differently C6-substituted oligogalacturonides

NARCIS (Netherlands)

Alebeek, van G.J.W.M.; Christensen, T.M.I.E.; Schols, H.A.; Mikkelsen, J.D.; Voragen, A.G.J.

2002-01-01

A thorough investigation of the mode of action of Aspergillus niger (4M-147) pectin lyase A (PLA) on differently C6-substituted oligogalacturonides is described. PLA appeared to be very specific for fully methyl-esterified oligogalacturonides: removal of the methyl-ester or changing the type of

Kinetic Resolution and Stereoselective Synthesis of 3-Substituted Aspartic Acids by Using Engineered Methylaspartate Ammonia Lyases

NARCIS (Netherlands)

Raj, Hans; Szymanski, Wiktor; Villiers, Jandré de; Puthan Veetil, Vinod; Quax, Wim J.; Shimamoto, Keiko; Janssen, Dick B.; Feringa, Ben L.; Poelarends, Gerrit J.

2013-01-01

Kinetic resolution and asymmetric synthesis of various valuable 3-substituted aspartic acids, which were obtained in fair to good yields with diastereomeric ratio values of up to >98:2 and enantiomeric excess values of up to >99 %, by using engineered methylaspartate ammonia lyases are described.

Method for separating mono- and di-octylphenyl phosphoric acid esters

International Nuclear Information System (INIS)

Arnold, W.D. Jr.

1977-01-01

A method for separating mono-octylphenyl phosphoric acid ester and di-octylphenyl phosphoric acid ester from a mixture thereof comprises reacting the ester mixture with a source of lithium or sodium ions to form a mixture of the phosphate salts; contacting the salt mixture with an organic solvent which causes the dioctylphenyl phosphate salt to be dissolved in the organic solvent phase and the mono-octylphenyl phosphate salt to exist in a solid phase; separating the phases; recovering the phosphate salts from their respective phases; and acidifying the recovered salts to form the original phosphoric acid esters

Uranium extraction in phosphoric acid

International Nuclear Information System (INIS)

Araujo Figueiredo, C. de

1984-01-01

Uranium is recovered from the phosphoric liquor produced from the concentrate obtained from phosphorus-uraniferous mineral from Itataia mines (CE, Brazil). The proposed process consists of two extraction cycles. In the first one, uranium is reduced to its tetravalent state and then extracted by dioctylpyrophosphoric acid, diluted in Kerosene. Re-extraction is carried out with concentrated phosphoric acid containing an oxidising agent to convert uranium to its hexavalent state. This extract (from the first cycle) is submitted to the second cycle where uranium is extracted with DEPA-TOPO (di-2-hexylphosphoric acid/tri-n-octyl phosphine oxide) in Kerosene. The extract is then washed and uranium is backextracted and precipitated as commercial concentrate. The organic phase is recovered. Results from discontinuous tests were satisfactory, enabling to establish operational conditions for the performance of a continuous test in a micro-pilot plant. (Author) [pt

Recovery of zinc in phosphor wastes via electrokinetic treatments

International Nuclear Information System (INIS)

Yu, M.Y.; Wang, H. Paul; Chen, C.Y.; Hsiung, T.-L.; Wei, Yu-Ling; Tai, H.-S.; Chiang, K.-C.

2007-01-01

Speciation of zinc in phosphor wastes during electrokinetic treatments has been studied by in situ X-ray absorption near edge structure (XANES) spectroscopy in the present work. The least-square fits of the in situ XANES spectra show that the major zinc species in the phosphor waste are ZnS (77%), ZnO (10%), and Zn(OH) 2 (13%). During the electrokinetic treatment for 90 min, 25% of ZnS and 4% of ZnO are dissolved. About 42% of zinc is enriched on the cathode under the electric field (5 V/cm). Prolonging the electrokinetic treatment time to 4 h under the electric field of 5 V/cm, at least 80% of zinc in the phosphor waste can be recovered

Quantitative Characterization of Phosphor Detector for Fusion Plasmas

International Nuclear Information System (INIS)

Baciero, A.; Zurro, B.; McCarthy, K. J.

2004-01-01

Experiments made to characterize phosphor screens with application as broadband radiation detectors, are described. Several radiation sources, covering the spectral range between the ultraviolet and X ray, were used. In addition, details are given of three original phosphor-screen-based detectors that were designed for use as broadband detectors in magnetically confined fusion devices. The first measurements obtained with these detectors in plasmas created in the TJ-II stellarator device are presented together with the analysis performed. (Author)

Carbon aerogel electrodes for direct energy conversion

Science.gov (United States)

Mayer, Steven T.; Kaschmitter, James L.; Pekala, Richard W.

1997-01-01

A direct energy conversion device, such as a fuel cell, using carbon aerogel electrodes, wherein the carbon aerogel is loaded with a noble catalyst, such as platinum or rhodium and soaked with phosphoric acid, for example. A separator is located between the electrodes, which are placed in a cylinder having plate current collectors positioned adjacent the electrodes and connected to a power supply, and a pair of gas manifolds, containing hydrogen and oxygen positioned adjacent the current collectors. Due to the high surface area and excellent electrical conductivity of carbon aerogels, the problems relative to high polarization resistance of carbon composite electrodes conventionally used in fuel cells are overcome.

Electrochemistry of cytochrome P450 17α-hydroxylase/17,20-lyase (P450c17).

Science.gov (United States)

Martin, Lisandra L; Kubeil, Clemens; Simonov, Alexandr N; Kuznetsov, Vladimir L; Corbin, C Jo; Auchus, Richard J; Conley, Alan J; Bond, Alan M; Rodgers, Raymond J

2017-02-05

Within the superfamily of cytochrome P450 enzymes (P450s), there is a small class which is functionally employed for steroid biosynthesis. The enzymes in this class appear to have a small active site to accommodate the steroid substrates specifically and snuggly, prior to the redox transformation or hydroxylation to form a product. Cytochrome P450c17 is one of these and is also a multi-functional P450, with two activities, the first 17α-hydroxylation of pregnenolone is followed by a subsequent 17,20-lyase transformation to dehydroepiandrosterone (DHEA) as the dominant pathways to cortisol precursors or androgens in humans, respectively. How P450c17 regulates these two redox reactions is of special interest. There is a paucity of direct electrochemical studies on steroidogenic P450s, and in this mini-review we provide an overview of these studies with P450c17. Historical consideration as to the difficulties in obtaining reliable electrochemistry due to issues of handling proteins on an electrode, together with advances in the electrochemical techniques are addressed. Recent work using Fourier transformed alternating current voltammetry is highlighted as this technique can provide both catalytic information simultaneously with the underlying redox transfer with the P450 haem. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Characteristics of activated carbon resulted from pyrolysis of the oil palm fronds powder

Science.gov (United States)

Maulina, S.; Iriansyah, M.

2018-02-01

Activated carbon is the product of a charcoal impregnation process that has a higher absorption capacity and has more benefits than regular char. Therefore, this study aims to cultivate the powder of oil palm fronds into activated carbon that meets the requirements of Standard National Indonesia 06-3730-1995. To do so, the carbonization process of the powder of oil palm fronds was carried out using a pyrolysis reactor for 30 minutes at a temperature of 150 °C, 200 °C, and 250 °C in order to produce activated char. Then, the char was impregnated using Phosphoric Acid activator (H3PO4) for 24 hours. Characteristics of activated carbon indicate that the treatment of char by chemical activation of oil palm fronds powder has an effect on the properties of activated carbon. The activated carbons that has the highest absorption properties to Iodine (822.91 mg/g) were obtained from the impregnation process with 15% concentration of Phosphoric Acid (H3PO4) at pyrolysis temperature of 200 °C. Furthermore, the activation process resulted in activated carbon with water content of 8%, ash content of 4%, volatile matter 39%, and fixed carbon 75%, Iodine number 822.91 mg/g.

Electroluminescent efficiency of alternating current thick film devices using ZnS:Cu,Cl phosphor

International Nuclear Information System (INIS)

Sharma, Gaytri; Han, Sang Do; Kim, Jung Duk; Khatkar, Satyender P.; Rhee, Young Woo

2006-01-01

ZnS:Cu,Cl phosphor is prepared with the help of low intensity milling of the precursor material in two step firing process. The synthesized phosphor is used for the preparation of alternating current thick film electroluminescent (ACTFEL) devices with screen-printing method. The commission international de l'Eclairge (CIE) color co-ordinates of the ACTFEL devices prepared by these phosphor layers shows a shift from bluish-green to green region with the change in the amount of Cu in the phosphor. The various parameters to improve the efficiency and luminance of the devices have also been investigated. The brightness of the ac thick film EL device depends on the particle size of the phosphor, crystallinity, amount of binding material and applied voltage. The EL device fabricated with phosphor having average particle size of 25 μm shows maximum luminescence, when 60% phosphor concentration is used with respect to binding material. EL intensity is also linearly dependent on frequency. It is due the increase of excitation chances of the host matrix or dopant ions with increasing frequency

High-efficient, bicolor-emitting GdVO_4:Dy"3"+ phosphor under near ultraviolet excitation

International Nuclear Information System (INIS)

Lu, Jinjin; Zhou, Jia; Jia, Huayu; Tian, Yue

2015-01-01

Bicolor emitting GdVO_4:Dy"3"+ phosphor with short columniation-shape was prepared via a simple co-precipitation process. The optimal doping concentration for obtaining maximal luminescent intensity was confirmed to be 0.3 mol% and the electric dipole–dipole interaction is responsible for concentration quenching of Dy"3"+ emission in GdVO_4 phosphor. In order to evaluate the luminescent performance of as-prepared phosphor, the luminescent efficiency and color coordinates were studied. The results show that luminescent efficiency of this phosphor is very high under near UV excitation and twice times higher than commercial Y_2O_2S:Eu"3"+ phosphor. In addition, the color coordinates for optimal Dy"3"+ concentration are (0.339, 0.379), which are close to equal energy point. Therefore, the GdVO_4:Dy"3"+ phosphor may have potential application for solid state lighting.

Freundlich adsorption isotherms of agricultural by-product-based powdered activated carbons in a geosmin-water system

Energy Technology Data Exchange (ETDEWEB)

Ng, Chilton [Food and Drug Administration, Dept. of Health and Human Services, Lenexa, KS (United States); Losso, Jack N.; Rao, Ramu M. [Louisiana State Univ. Agricultural Center, Dept. of Food Science, Baton Rouge, LA (United States); Marshall, Wayne E. [USDA-ARS, Southern Regional Research Center, New Orleans, LA (United States)

2002-11-01

The present study was designed to model the adsorption of geosmin from water under laboratory conditions using the Freundlich isotherm model. This model was used to compare the efficiency of sugarcane bagasse and pecan shell-based powdered activated carbon to the efficiency of a coal-based commercial activated carbon (Calgon Filtrasorb 400). When data were generated from Freundlich isotherms, Calgon Filtrasorb 400 had greater geosmin adsorption at all geosmin concentrations studied than the laboratory produced steam-activated pecan shell carbon, steam-activated bagasse carbon, and the CO{sub 2}-activated pecan shell carbon. At geosmin concentrations <0.07 {sup {mu}}g/l for the phosphoric acid-activated pecan shell carbon and below 0.08 {sup {mu}}g/l for a commercially produced steam-activated pecan shell carbon obtained from Scientific Carbons, these two carbons had a higher calculated geosmin adsorption than Filtrasorb 400. While the commercial carbon was more efficient than some laboratory prepared carbons at most geosmin concentrations, the results indicate that when the amount of geosmin was below the threshold level of human taste (about 0.10 {sup {mu}}g/l), the phosphoric acid-activated pecan shell carbon and the Scientific Carbons sample were more efficient than Filtrasorb 400 at geosmin removal. (Author)

Bifurcated Degradative Pathway of 3-Sulfolactate in Roseovarius nubinhibens ISM via Sulfoacetaldehyde Acetyltransferase and (S)-Cysteate Sulfolyase ▿ †

Science.gov (United States)

Denger, Karin; Mayer, Jutta; Buhmann, Matthias; Weinitschke, Sonja; Smits, Theo H. M.; Cook, Alasdair M.

2009-01-01

Data from the genome sequence of the aerobic, marine bacterium Roseovarius nubinhibens ISM were interpreted such that 3-sulfolactate would be degraded as a sole source of carbon and energy for growth via a novel bifurcated pathway including two known desulfonative enzymes, sulfoacetaldehyde acetyltransferase (EC 2.3.3.15) (Xsc) and cysteate sulfo-lyase (EC 4.4.1.25) (CuyA). Strain ISM utilized sulfolactate quantitatively with stoichiometric excretion of the sulfonate sulfur as sulfate. A combination of enzyme assays, analytical chemistry, enzyme purification, peptide mass fingerprinting, and reverse transcription-PCR data supported the presence of an inducible, tripartite sulfolactate uptake system (SlcHFG), and a membrane-bound sulfolactate dehydrogenase (SlcD) which generated 3-sulfopyruvate, the point of bifurcation. 3-Sulfopyruvate was in part decarboxylated by 3-sulfopyruvate decarboxylase (EC 4.1.1.79) (ComDE), which was purified. The sulfoacetaldehyde that was formed was desulfonated by Xsc, which was identified, and the acetyl phosphate was converted to acetyl-coenzyme A by phosphate acetyltransferase (Pta). The other portion of the 3-sulfopyruvate was transaminated to (S)-cysteate, which was desulfonated by CuyA, which was identified. The sulfite that was formed was presumably exported by CuyZ (TC 9.B.7.1.1 in the transport classification system), and a periplasmic sulfite dehydrogenase is presumed. Bioinformatic analyses indicated that transporter SlcHFG is rare but that SlcD is involved in three different combinations of pathways, the bifurcated pathway shown here, via CuyA alone, and via Xsc alone. This novel pathway involves ComDE in biodegradation, whereas it was discovered in the biosynthesis of coenzyme M. The different pathways of desulfonation of sulfolactate presumably represent final steps in the biodegradation of sulfoquinovose (and exudates derived from it) in marine and aquatic environments. PMID:19581363

Influência da densidade populacional nas relações entre matéria orgânica carbonácea, nitrogênio e fósforo em rios urbanos situados em áreas com baixa cobertura sanitária Influence of the urban density in the relationship among carbonic organic matter, nitrogen and phosphorous in small rivers with low sanitation coverage

Directory of Open Access Journals (Sweden)

Harry Alberto Bollmann

2006-12-01

Full Text Available O objetivo principal deste trabalho é a análise da variação da relação entre a matéria orgânica carbonácea (representada pelas Demandas Biológica e Bioquímica de Oxigênio, Nitrogênio Total Kjeldhal e Fósforo Total nas águas de pequenos rios urbanos cujas áreas de drenagem apresentem baixa cobertura sanitária. Para isso, foram selecionadas 4 bacias hidrográficas urbanas com ocupação residencial, densidade populacional entre 0 e 100 hab/ha e similaridade de condições naturais e de ocupação humana. Os resultados mostraram alterações importantes nas relações entre os conteúdos de matéria orgânica carbonácea, Nitrogênio e Fósforo indicando que, a partir de uma condição natural não urbanizada, mesmo pequenas densidades populacionais são capazes de alterar significativamente a qualidade das águas.The purpose of this study is to evaluate the relationship among the carbonic organic matter (measured as Chemical and Biological Oxygen Demand, Total Kjeldhal Nitrogen and Total Phosphorous in small urban rivers with low sanitation coverage in its hydrographic basins. Four basins with similar natural condition and residential occupation but variable urban densities between 0 and 100 inhabitants per hectare were selected. The results show important changes in the carbonic organic matter, Nitrogen and Phosphorous relationships indicating that, compared with a natural condition, even low urban densities can significantly change de water quality.

Phosphors for near UV-Emitting LED's for Efficacious Generation of White Light

Energy Technology Data Exchange (ETDEWEB)

McKittrick, Joanna [Univ. of California, San Diego, CA (United States)

2013-09-30

1) We studied phosphors for near-UV (nUV) LED application as an alternative to blue LEDs currently being used in SSL systems. We have shown that nUV light sources could be very efficient at high current and will have significantly less binning at both the chip and phosphor levels. We identified phosphor blends that could yield 4100K lamps with a CRI of approximately 80 and LPWnUV,opt equal to 179 for the best performing phosphor blend. Considering the fact that the lamps were not optimized for light coupling, the results are quite impressive. The main bottleneck is an optimum blue phosphor with a peak near 440 nm with a full width half maximum of about 25 nm and a quantum efficiency of >95%. Unfortunately, that may be a very difficult task when we want to excite a phosphor at ~400 nm with a very small margin for Stokes shift. Another way is to have all the phosphors in the blend having the excitation peak at 400 nm or slightly shorter wavelength. This could lead to a white light source with no body color and optimum efficacy due to no self-absorption effects by phosphors in the blend. This is even harder than finding an ideal blue phosphor, but not necessarily impossible. 2) With the phosphor blends identified, light sources using nUV LEDs at high current could be designed with comparable efficacy to those using blue LEDs. It will allow us to design light sources with multiple wattages using the same chips and phosphor blends simply by varying the input current. In the case of blue LEDs, this is not currently possible because varying the current will lower the efficacy at high current and alter the color point. With improvement of phosphor blends, control over CRI could improve. Less binning at the chip level and also at the phosphor blend level could reduce the cost of SSL light sources. 3) This study provided a deeper understanding of phosphor characteristics needed for LEDs in general and nUV LEDs in particular. Two students received Ph.D. degrees and three

Lactic acid bacteria involved in cocoa beans fermentation from Ivory Coast: Species diversity and citrate lyase production.

Science.gov (United States)

Ouattara, Hadja D; Ouattara, Honoré G; Droux, Michel; Reverchon, Sylvie; Nasser, William; Niamke, Sébastien L

2017-09-01

Microbial fermentation is an indispensable process for high quality chocolate from cocoa bean raw material. lactic acid bacteria (LAB) are among the major microorganisms responsible for cocoa fermentation but their exact role remains to be elucidated. In this study, we analyzed the diversity of LAB in six cocoa producing regions of Ivory Coast. Ribosomal 16S gene sequence analysis showed that Lactobacillus plantarum and Leuconostoc mesenteroides are the dominant LAB species in these six regions. In addition, other species were identified as the minor microbial population, namely Lactobacillus curieae, Enterococcus faecium, Fructobacillus pseudoficulneus, Lactobacillus casei, Weissella paramesenteroides and Weissella cibaria. However, in each region, the LAB microbial population was composed of a restricted number of species (maximum 5 species), which varied between the different regions. LAB implication in the breakdown of citric acid was investigated as a fundamental property for a successful cocoa fermentation process. High citrate lyase producer strains were characterized by rapid citric acid consumption, as revealed by a 4-fold decrease in citric acid concentration in the growth medium within 12h, concomitant with an increase in acetic acid and lactic acid concentration. The production of citrate lyase was strongly dependent on environmental conditions, with optimum production at acidic pH (pHfermentation. This study reveals that one of the major roles of LAB in the cocoa fermentation process involves the breakdown of citric acid during the early stage of cocoa fermentation through the activity of citrate lyase. Copyright © 2017 Elsevier B.V. All rights reserved.

Evolution and Adaptation of Phytoplankton Photosynthetic Pathways to perturbations of the geological carbon system

Science.gov (United States)

Rickaby, R. E.; Young, J. N.; Hermoso, M.; Heureux, A.; McCLelland, H.; Lee, R.; Eason Hubbard, M.

2012-12-01

The ocean and atmosphere carbon system has varied greatly over geological history both in response to initial evolutionary innovation, and as a driver of adaptive change. Here we establish that positive selection in Rubisco, the most abundant enzyme on the Earth responsible for all photosynthetic carbon fixation, occurred early in Earth's history, and basal to the radiation of the modern marine algal groups. Our signals of positive selection appear to be triggered by changing intracellular concentrations of carbon dioxide (CO2) due to the emergence of carbon concentrating mechanisms between 1.56 and 0.41 Ba in response to declining atmospheric CO2 . We contend that, at least in terms of carbon, phytoplankton generally were well poised to manage subsequent abrupt carbon cycle perturbations. The physiological pathways for optimising carbon acquisition across a wide range of ambient carbon dioxide concentrations had already been established and were genetically widespread across open ocean phytoplankton groups. We will further investigate some case studies from the Mesozoic and Cenozoic abrupt carbon cycle excursions using isotopic tools to probe the community photosynthetic response and demonstrate the flexibility of phytoplankton photosynthesis in the face of major perturbations. In particular, an unprecedented resolution record across the Toarcian (Early Jurassic) carbon isotope excursion in the Paris Basin reveals a selection and evolution towards a community reliant solely on diffusive carbon dioxide supply for photosynthesis at the height of the excursion at 1500-2500 ppm CO2. The continued flourishing of the phytoplankton biological pump throughout this excursion was able to remove the excess carbon injected into the water column in less than 45 kyrs.

Involvement of plasma membrane peroxidases and oxylipin pathway in the recovery from phytoplasma disease in apple (Malus domestica).

Science.gov (United States)

Patui, Sonia; Bertolini, Alberto; Clincon, Luisa; Ermacora, Paolo; Braidot, Enrico; Vianello, Angelo; Zancani, Marco

2013-06-01

Apple trees (Malus domestica Borkh.) may be affected by apple proliferation (AP), caused by 'Candidatus Phytoplasma mali'. Some plants can spontaneously recover from the disease, which implies the disappearance of symptoms through a phenomenon known as recovery. In this article it is shown that NAD(P)H peroxidases of leaf plasma membrane-enriched fractions exhibited a higher activity in samples from both AP-diseased and recovered plants. In addition, an increase in endogenous SA was characteristic of the symptomatic plants, since its content increased in samples obtained from diseased apple trees. In agreement, phenylalanine ammonia lyase (PAL) activity, a key enzyme of the phenylpropanoid pathway, was increased too. Jasmonic acid (JA) increased only during recovery, in a phase subsequent to the pathological state, and in concomitance to a decline of salicylic acid (SA). Oxylipin pathway, responsible for JA synthesis, was not induced during the development of AP-disease, but it appeared to be stimulated when the recovery occurred. Accordingly, lipoxygenase (LOX) activity, detected in plasma membrane-enriched fractions, showed an increase in apple leaves obtained from recovered plants. This enhancement was paralleled by an increase of hydroperoxide lyase (HPL) activity, detected in leaf microsomes, albeit the latter enzyme was activated in either the disease or recovery conditions. Hence, a reciprocal antagonism between SA- and JA-pathways could be suggested as an effective mechanism by which apple plants react to phytoplasma invasions, thereby providing a suitable defense response leading to the establishment of the recovery phenomenon. Copyright © Physiologia Plantarum 2012.

Luminescence and electron degradation properties of Bi doped CaO phosphor

Energy Technology Data Exchange (ETDEWEB)

Yousif, A. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa); Department of Physics, Faculty of Education, University of Khartoum, P.O. Box 321, 11115 Omdurman (Sudan); Kroon, R.E.; Coetsee, E.; Ntwaeaborwa, O.M. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa); Seed Ahmed, H.A.A. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa); Department of Physics, Faculty of Education, University of Khartoum, P.O. Box 321, 11115 Omdurman (Sudan); Swart, H.C., E-mail: swarthc@ufs.ac.za [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa)

2015-11-30

Graphical abstract: - Highlights: • Blue emitting Ca{sub 1−x}O:Bi{sub x=0.5%} phosphor powder was successfully prepared. • Strong blue near-UV emission was obtained. • Electron beam induced cathodoluminescence intensity degradation occurred. • XPS was successfully used to explain the degradation process. - Abstract: Ca{sub 1−x}O:Bi{sub x=0.5%} phosphor powder was successfully synthesized by the sol-gel combustion method. The structure, morphology and luminescent properties of the phosphor were characterized by X-ray diffraction, scanning electron microscopy, photoluminescence and cathodoluminescence (CL) spectroscopy. The results showed that the Ca{sub 1−x}O:Bi{sub x=0.5%} consisted of single face-centred cubic crystals and that the phosphor particles were uniformly distributed. When the phosphor was excited by a xenon lamp at 355 nm, or a 325 nm He–Cd laser, or electron beam, it emitted strongly in the blue near-UV range with a wavelength of 395 nm ({sup 3}P{sub 1} → {sup 1}S{sub 0} transition of Bi{sup 3+}). The CL intensity was monitored as a function of the accelerating voltage and also as a function of the beam current. The powder was also subjected to a prolonged electron beam irradiation to study the electron beam induced CL intensity degradation. X-ray photoelectron spectroscopy was used to analyze the Ca{sub 1−x}O:Bi{sub x=0.5%} phosphor sample surface before and after degradation.

Phosphorous Diffuser Diverged Blue Laser Diode for Indoor Lighting and Communication

KAUST Repository

Chi, Yu-Chieh

2015-12-21

An advanced light-fidelity (Li-Fi) system based on the blue Gallium nitride (GaN) laser diode (LD) with a compact white-light phosphorous diffuser is demonstrated for fusing the indoor white-lighting and visible light communication (VLC). The phosphorous diffuser adhered blue GaN LD broadens luminescent spectrum and diverges beam spot to provide ample functionality including the completeness of Li-Fi feature and the quality of white-lighting. The phosphorous diffuser diverged white-light spot covers a radiant angle up to 120o with CIE coordinates of (0.34, 0.37). On the other hand, the degradation on throughput frequency response of the blue LD is mainly attributed to the self-feedback caused by the reflection from the phosphor-air interface. It represents the current state-of-the-art performance on carrying 5.2-Gbit/s orthogonal frequency-division multiplexed 16-quadrature-amplitude modulation (16-QAM OFDM) data with a bit error rate (BER) of 3.1 × 10−3 over a 60-cm free-space link. This work aims to explore the plausibility of the phosphorous diffuser diverged blue GaN LD for future hybrid white-lighting and VLC systems.

Oxygen Reduction on Gas-Diffusion Electrodes for Phosphoric Acid Fuel Cells by a Potential Decay Method

DEFF Research Database (Denmark)

Li, Qingfeng; Gang, Xiao; Hjuler, Hans Aage

1995-01-01

The reduction of gaseous oxygen on carbon supported platinum electrodes has been studied at 150 degrees C with polarization and potential decay measurements. The electrolyte was either 100 weight percent phosphoric acid or that acid with a fluorinated additive, potassium perfluorohexanesulfonate ......6F13SO3K). The pseudo-Tafel curves of the overpotential vs. log (ii(L)/(i(L) - i)) show a two-slope behavior, probably due to different adsorption mechanisms. The potential relaxations as functions of log (t + tau) and log (-d eta/dt) have been plotted. The variations of these slopes...

Luminescence properties of dysprosium doped calcium magnesium silicate phosphor by solid state reaction method

Energy Technology Data Exchange (ETDEWEB)

Sahu, Ishwar Prasad, E-mail: ishwarprasad1986@gmail.com [School of Studies in Physics & Astrophysics, Pt. Ravishankar Shukla University, Raipur, C.G. 492010 (India); Chandrakar, Priya; Baghel, R.N.; Bisen, D.P.; Brahme, Nameeta [School of Studies in Physics & Astrophysics, Pt. Ravishankar Shukla University, Raipur, C.G. 492010 (India); Tamrakar, Raunak Kumar [Department of Applied Physics, Bhilai Institute of Technology, Durg, C.G. 491001 (India)

2015-11-15

Dysprosium doped calcium magnesium silicate (CaMgSi{sub 2}O{sub 6}:Dy{sup 3+}) white light emitting phosphor was synthesized by solid state reaction process. The crystal structure of sintered phosphor was monoclinic structure with space group C2/c. Chemical composition of the sintered CaMgSi{sub 2}O{sub 6}:Dy{sup 3+} phosphor was confirmed by EDX. The prepared CaMgSi{sub 2}O{sub 6}:Dy{sup 3+} phosphor was excited from 352 nm and their corresponding emission spectra were recorded at blue (470 nm), yellow (570 nm) and red (675 nm) line due to the {sup 4}F{sub 9/2} → {sup 6}H{sub 15/2}, {sup 4}F{sub 9/2} → {sup 6}H{sub 13/2}, {sup 4}F{sub 9/2} → {sup 6}H{sub 11/2} transitions of Dy{sup 3+} ions. The combination of these three emissions constituted as white light confirmed by the Commission Internationale de L'Eclairage (CIE) chromatic coordinate diagram. The possible mechanism of the white light emitting long lasting CaMgSi{sub 2}O{sub 6}:Dy{sup 3+} phosphor was also investigated. Investigation on afterglow property show that phosphor held fast and slow decay process. The peak of mechanoluminescence (ML) intensity increases linearly with increasing impact velocity of the moving piston. Thus the present investigation indicates that the local piezoelectricity-induced electron bombardment model is responsible to produce ML in prepared CaMgSi{sub 2}O{sub 6}:Dy{sup 3+} phosphor. - Highlights: • The crystal structure of CaMgSi{sub 2}O{sub 6}:Dy{sup 3+} phosphor is consistent with standard monoclinic structure. • CIE coordinates of CaMgSi{sub 2}O{sub 6}:Dy{sup 3+} phosphor is suitable as white light emitting phosphor. • The local piezoelectricity-induced electron bombardment model is responsible to produce ML in CaMgSi{sub 2}O{sub 6}:Dy{sup 3+} phosphor.

Characterization of the serine acetyltransferase gene family of Vitis vinifera uncovers differences in regulation of OAS synthesis in woody plants

OpenAIRE

Silvia eTavares; Silvia eTavares; Markus eWirtz; Marcel Pascal Beier; Jochen eBogs; Jochen eBogs; Jochen eBogs; Ruediger eHell; Sara eAmâncio

2015-01-01

In higher plants cysteine biosynthesis is catalyzed by O-acetylserine(thiol)lyase (OASTL) and represents the last step of the assimilatory sulfate reduction pathway. It is mainly regulated by provision of O-acetylserine (OAS), the nitrogen/carbon containing backbone for fixation of reduced sulfur. OAS is synthesized by Serine acetyltransferase (SERAT), which reversibly interacts with OASTL in the cysteine synthase complex (CSC). In this study we identify and characterize the SERAT protein fam...

Characterization of the serine acetyltransferase gene family of Vitis vinifera uncovers differences in regulation of OAS synthesis in woody plants

OpenAIRE

Tavares, Sílvia; Wirtz, Markus; Beier, Marcel P.; Bogs, Jochen; Hell, Rüdiger; Amâncio, Sara

2015-01-01

In higher plants cysteine biosynthesis is catalyzed by O-acetylserine(thiol)lyase (OASTL) and represents the last step of the assimilatory sulfate reduction pathway. It is mainly regulated by provision of O-acetylserine (OAS), the nitrogen/carbon containing backbone for fixation of reduced sulfur. OAS is synthesized by Serine acetyltransferase (SERAT), which reversibly interacts with OASTL in the cysteine synthase complex (CSC). In this study we identify and characterize the SERAT gene family...

Flocculation of suspended matter in a crude wet phosphoric acid (Algeria)

International Nuclear Information System (INIS)

Brikci Nigassa, M.; Bensebaa, A.

1994-11-01

Prior to the recovery of uranium, a pre-treatment of the phosphoric acid is necessary to remove soluble impurities of different origins. In this work, synthetic flocculants have been used. the influence of operating conditions on flocculation and filtration, such as, type of flocculants, polymer concentration, temperature, mixing and time of agitation, has been studied for both aged and fresh phosphoric acid. It has been shown that synthetic flocculants can be used for flocculation ins a phosphoric acid medium and that flocculation and filtration processes are strongly linked

Possible regulatory role of phenylalanine ammonia-lyase in the production of anthocyanins in asparagus (Asparagus officinalis L)

NARCIS (Netherlands)

Flores, F.B.; Oosterhaven, J.; Martinez-Madrid, M.C.; Romojaro, F.

2005-01-01

The regulatory role of phenylalanine ammonia-lyase (PAL) in the light-induced accumulation of anthocyanins in the epidermis of asparagus spears has been analysed. A correlation between the stimulation of PAL activity and the rise in total anthocyanin content has been observed. Light radiation

Scaling Up: Kilolumen Solid-State Lighting Exceeding 100 LPW via Remote Phosphor

Energy Technology Data Exchange (ETDEWEB)

Waqidi Falicoff

2008-09-15

This thirty-month project was successful in attaining its ambitious objectives of demonstrating a radically novel 'remote-phosphor' LED light source that can out-perform conventional conformal coated phosphor LED sources. Numerous technical challenges were met with innovative techniques and optical configurations. This product development program for a new generation of solid-state light sources has attained unprecedented luminosity (over 1 kilo-lumen) and efficacy (based on the criterion lumens per 100mw radiant blue). LPI has successfully demonstrated its proprietary technology for optical synthesis of large uniform sources out of the light output of an array of separated LEDs. Numerous multiple blue LEDs illuminate single a phosphor patch. By separating the LEDs from the phosphor, the phosphor and LEDs operate cooler and with higher efficiency over a wide range of operating conditions (from startup to steady state). Other benefits of the system include: better source uniformity, more types of phosphor can be used (chemical interaction and high temperatures are no longer an issue), and the phosphor can be made up from a pre-manufactured sheet (thereby lowering cost and complexity of phosphor deposition). Several laboratory prototypes were built and operated at the expected high performance level. The project fully explored two types of remote phosphor system: transmissive and reflective. The first was found to be well suited for a replacement for A19 type incandescent bulbs, as it was able to replicate the beam pattern of a traditional filament bulb. The second type has the advantages that it is pre-collimate source that has an adjustable color temperature. The project was divided in two phases: Phase I explored a transmissive design and Phase II of the project developed reflective architectures. Additionally, in Phase II the design of a spherical emitting transmissive remote phosphor bulb was developed that is suitable for replacement of A19 and

TL-OSL study of Li{sub 3}PO{sub 4}: Mg, Cu phosphor

Energy Technology Data Exchange (ETDEWEB)

Rahangdale, S. R., E-mail: sachin.rahangdale1@gmail.com; Wankhede, S. P. [Department of Physics, K.D.K.College of Engineering, Nagpur (India); Dhabekar, B. S. [RPAD, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Palikundwar, U. A.; Moharil, S. V. [Department of Physics, RTM Nagpur University, Nagpur, 440010 (India)

2015-08-28

In the present work, we report the thermoluminescence and optically stimulated luminescence properties of Mg and Cu doped Li{sub 3}PO{sub 4} phosphor. The phosphor was synthesized by precipitation method. The thermoluminescence dosimetric peak temperature for the phosphor varies with concentrations of Mg and Cu. Li{sub 3}PO{sub 4} shows good response to 470nm optical stimulation. The OSL sensitivity of the phosphor is approximately 12 times than that of standard Lithium magnesium phosphate. This study may help to develop this material for the application in real time dosimetry using optically stimulated luminescence.

Synthesis and characterization of tunable coumarin- linked glasses as new class of organic/inorganic phosphors

Energy Technology Data Exchange (ETDEWEB)

Luridiana, Alberto; Pretta, Gianluca; Secci, Francesco; Frongia, Angelo [Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, Complesso universitario di Monserrato, SS 554, bivio per Sestu, Monserrato (Canada) (Italy); Chiriu, Daniele; Carbonaro, Carlo Maria; Corpino, Riccardo [Dipartimento di Fisica, Università degli Studi di Cagliari, Complesso universitario di Monserrato, SS 554, bivio per Sestu, Monserrato (Canada) (Italy); Ricci, Pier Carlo, E-mail: carlo.ricci@dsf.unica.it [Dipartimento di Fisica, Universitá degli Studi di Cagliari, S.P. Monserrato-Sestu Km 0,700, 09042 Monserrato (Canada) (Italy)

2014-10-21

It is well known that stilbene with a trans conformation is highly fluorescent. From the viewpoint of molecular structure, coumarins bear a carbon-carbon double bond which is fixed as trans conformation as in trans-stilbene through a lactone structure. This can help to avoid the trans-cis transformation of the double bond under ultraviolet (UV) irradiation as observed in stilbene compounds and results in strong fluorescence and high fluorescence quantum yield and photostability in most of coumarin derivatives. Herein we report some preliminary results about the synthesis and spectroscopic characterization of tunable coumarins and the development of a new linkage protocol for the obtainment of monolayer coumarin-covalently linked glasses. The resulting organic/inorganic coumarin/silica based Self-Assembled Monolayer (SMA) film is proposed as new phosphors for the substituting of critical raw materials, like rare earths, in photonics applications.

Technique of proton and phosphorous MR spectroscopy; Technik der Protonen- und Phosphor-MR-Spektroskopie

Energy Technology Data Exchange (ETDEWEB)

Backens, M. [Universitaetsklinikum des Saarlandes, Klinik fuer Diagnostische und Interventionelle Neuroradiologie, Homburg/Saar (Germany)

2017-06-15

Magnetic resonance spectroscopy (MRS) is an important non-invasive method that can reveal the concentration and spatial distribution of particular biochemically relevant tissue metabolites. Proton MRS is routinely applicable in the clinical setting providing good quality results even with a moderate magnetic field strength of 1.5 T. Relative values of metabolite concentrations are mostly used for the assessment of metabolic disorders. Absolute quantification of metabolites can be achieved by means of internal or external reference scans. Phosphorous MRS extends the range of detectable molecules to energy and cell membrane metabolism. The lower detection limit of metabolite concentrations is in the range of some mmol/kg. Depending on the magnetic field strength, MRS enables a spatial resolution of a few milliliters. The use of phosphorous MRS is considerably limited because higher field strengths of at least 3.0 T and additional expensive hardware for signal processing are required. (orig.) [German] Die MR-Spektroskopie (MRS) ist eine wichtige nichtinvasive Untersuchungsmethode, die Konzentration und raeumliche Verteilung einiger biochemisch relevanter Metaboliten im Gewebe ermitteln kann. Die Protonenspektroskopie ist klinisch etabliert, in der Routine einfach durchfuehrbar und liefert bereits bei einer Magnetfeldstaerke von 1,5 T qualitativ gute Ergebnisse. Fuer die Beurteilung von Stoffwechselveraenderungen werden Metabolitenkonzentrationen meist als Relativwerte angegeben. Mithilfe interner oder externer Referenzmessungen sind auch absolute Metabolitenkonzentrationen berechenbar. Die Phosphorspektroskopie erweitert den Bereich der detektierbaren Molekuele auf den Energie- und Zellmembranstoffwechsel. Die minimale nachweisbare Metabolitenkonzentration liegt bei einigen mmol/kg. Abhaengig von der Magnetfeldstaerke ist eine raeumliche Aufloesung der MRS von wenigen Millilitern erreichbar. Der Einsatz der Phosphor-MRS wird dadurch erheblich eingeschraenkt, dass sie

Contrast and decay of cathodoluminescence from phosphor particles in a scanning electron microscope

Energy Technology Data Exchange (ETDEWEB)

Engelsen, Daniel den; Harris, Paul G.; Ireland, Terry G., E-mail: terry.ireland@brunel.ac.uk; Fern, George R.; Silver, Jack

2015-10-15

Cathodoluminescence (CL) studies are reported on phosphors in a field emission scanning electron microscope (FESEM). ZnO: Zn and other luminescent powders manifest a bright ring around the periphery of the particles: this ring enhances the contrast. Additionally, particles resting on top of others are substantially brighter than underlying ones. These phenomena are explained in terms of the combined effects of electrons backscattered out of the particles, together with light absorption by the substrate. The contrast is found to be a function of the particle size and the energy of the primary electrons. Some phosphor materials exhibit a pronounced comet-like structure at high scan rates in a CL-image, because the particle continues to emit light after the electron beam has moved to a position without phosphor material. Image analysis has been used to study the loss of brightness along the tail and hence to determine the decay time of the materials. The effect of phosphor saturation on the determination of decay times by CL-microscopy was also investigated. - Highlights: • Contrast enhancement are observed in secondary electron and cathodoluminescent images of phosphor particles sitting on top of others. • Backscattered electrons largely explain the observed contrast enhancement. • After glow effects in CL-micrographs of phosphors enable the determination of decay times. • Phosphor saturation can be used to determine the decay time of individual spectral transitions.

Salt-embedded carbon nanodots as a UV and thermal stable fluorophore for light-emitting diodes

International Nuclear Information System (INIS)

Kim, Tak H.; Wang, Fu; McCormick, Paul; Wang, Lianzhou; Brown, Chris; Li, Qin

2014-01-01

UV and thermal stable, photoluminescent carbon dots (CDs) prepared by embedding CDs in ionic salt crystals such as NaCl, KCl, KBr are demonstrated. The salt crystal embedding matrix does not interfere with CDs strong emission, and provides effective protection to CDs from the environment. The degradation of 20% of the initial luminescence intensity of salt-encapsulated CDs (S-CDs) is 15 times slower under UV and 6 times slower under heat compared to that of CDs in silica matrix. We also demonstrate that the S-CDs can be applied as a color-converting phosphor for typical GaN UV light emitting diodes (LEDs) with significant improvements in stability as well as processability. - Highlights: • Carbon dots can be uniformly embedded in ionic salt crystals via crystallization. • Salt crystals provide oxygen-tight matrices for protecting carbon dots from degradations. • Salt-embedded carbon dots can be applied as a stable color-converting phosphor in LEDs

Salt-embedded carbon nanodots as a UV and thermal stable fluorophore for light-emitting diodes

Energy Technology Data Exchange (ETDEWEB)

Kim, Tak H. [Queensland Micro- and Nano-Technology Centre, Griffith University, Nathan, QLD 4111 (Australia); Environmental Engineering, Griffith University, QLD 4111 (Australia); Wang, Fu [Institute of Physiology, University of Freiburg, Hermann-Herder-Street 7, 79104 Freiburg (Germany); McCormick, Paul [School of Mechanical and Chemical Engineering, The University of Western Australia, WA 2009 (Australia); Wang, Lianzhou [School of Chemical Engineering, The University of Queensland, QLD 4072 (Australia); Brown, Chris [Queensland Micro- and Nano-Technology Centre, Griffith University, Nathan, QLD 4111 (Australia); Li, Qin, E-mail: qin.li@griffith.edu.au [Queensland Micro- and Nano-Technology Centre, Griffith University, Nathan, QLD 4111 (Australia); Environmental Engineering, Griffith University, QLD 4111 (Australia)

2014-10-15

UV and thermal stable, photoluminescent carbon dots (CDs) prepared by embedding CDs in ionic salt crystals such as NaCl, KCl, KBr are demonstrated. The salt crystal embedding matrix does not interfere with CDs strong emission, and provides effective protection to CDs from the environment. The degradation of 20% of the initial luminescence intensity of salt-encapsulated CDs (S-CDs) is 15 times slower under UV and 6 times slower under heat compared to that of CDs in silica matrix. We also demonstrate that the S-CDs can be applied as a color-converting phosphor for typical GaN UV light emitting diodes (LEDs) with significant improvements in stability as well as processability. - Highlights: • Carbon dots can be uniformly embedded in ionic salt crystals via crystallization. • Salt crystals provide oxygen-tight matrices for protecting carbon dots from degradations. • Salt-embedded carbon dots can be applied as a stable color-converting phosphor in LEDs.

Structural and spectral properties of MgZnO2:Sm3+ phosphor

Science.gov (United States)

Rajput, Preasha; Sharma, Pallavi; Biswas, Pankaj; Kamni

2018-05-01

The samarium doped MgZnO2 phosphor was synthesized by the low-cost combustion method. The powder X-ray diffraction (XRD) analysis confirmed the crystallinity and phase purity of the phosphor. The lattice parameters were determined by indexing the diffraction peaks. The photoluminescence (PL) study revealed that the phosphor exhibited a broad excitation band in the UV region ranging between 200 to 350 nm. The 601 nm emission was ascribed to 4G5/2 to 6H7/2 transitions of the Sm3+ ion. The optical bandgap of MgZnO2:Sm3+ was obtained to be 3.56 eV. The phosphor can be projected as a useful material in X- and gamma-ray scintillators.

Critical issues in enhancing brightness in thin film phosphors for flat-panel display applications

International Nuclear Information System (INIS)

Singh, R.K.; Chen, Z.; Kumar, D.; Cho, K.; Ollinger, M.

2002-01-01

Thin film phosphors have potential applications in field emission flat-panel displays. However, they are limited by the lower cathodoluminescent brightness in comparison to phosphor powders. In this paper, we have investigated the critical parameters that need to be optimized to increase the brightness of phosphor thin films. Specifically, we studied the role of surface roughness and optical properties of the substrate on the brightness of the phosphor films. Thin Y 2 O 3 :Eu phosphor films were deposited on various substrates (lanthanum aluminate, quartz, sapphire, and silicon) with thicknesses varying from 50 to 500 nm. A model that accounts for diffuse and specular or scattering effects has been developed to understand the effects of the microstructure on the emission characteristics of the cathodoluminescent films. The results from the model show that both the optical properties of the substrate and the surface roughness of the films play a critical role in controlling the brightness of laser deposited phosphor films

Scenario analysis of China's emissions pathways in the 21st century for low carbon transition

International Nuclear Information System (INIS)

Wang Tao; Watson, Jim

2010-01-01

China's growing demand for energy - and its dependence on coal - has seen its carbon emissions increase more than 50% since 2000. Within the debate about mitigating global climate change, there is mounting pressure for emerging economies like China to take more responsibility for reducing their carbon emissions within a post-2012 international climate change policy framework. For China, this leads to fundamental questions about how feasible it is for the country to shift away from its recent carbon intensive pattern of growth. This paper presents some general results of scenarios that have been developed to investigate how China might continue to develop within a cumulative carbon emissions budget. The results show how changes in the key sectors of the Chinese economy could enable China to follow four different low carbon development pathways, each of which complies with a cumulative emissions constraint. Each scenario reflects different priorities for governmental decision making, infrastructure investments and social preferences. Having compared the key features of each scenario, the paper concludes with some implications for Chinese government policy.

Mechanoluminescence and photoluminescence of Pr3+ activated KMgF3 phosphor

International Nuclear Information System (INIS)

Dhoble, S.J.; Kher, R.S.; Furetta, C.

2003-01-01

A Czochralski method for the preparation of crystalline KMgF 3 : Pr phosphors are reported. Photoluminescence (PL) and mechanoluminescence (ML) characteristics are studied. Photoluminescence of Pr 3+ activated KMgF 3 shows the strong emission of Pr 3+ ions were observed at 498 and 650 nm by excitation of 213 mn. ML of KMgF 3 : Pr 3+ shows two peaks, which have been observed in ML intensity versus time curve. The ML peak shows the recombination of electrons with free radical (anion radical produced by γ-irradiation) released from two type traps during the mechanical pressure applied on KMgF 3 : Pr 3+ phosphor. It has a supra linear ML response with γ-ray exposure and a negligible fading. These properties of phosphor should be suitable in dosimetry of ionization relation using ML technique. Therefore the KMgF 3 : Pr 3+ phosphor proposed for ML dosimetry of ionization radiations. (Author)

Pathways to a low-carbon economy for the UK with the macro-econometric E3MG model

International Nuclear Information System (INIS)

Dagoumas, A.S.; Barker, T.S.

2010-01-01

This paper examines different carbon pathways for achieving deep CO 2 reduction targets for the UK using a macro-econometric hybrid model E3MG, which stands for Energy-Economy-Environment Model at the Global level. The E3MG, with the UK as one of its regions, combines a top-down approach for modeling the global economy and for estimating the aggregate and disaggregate energy demand and a bottom-up approach (Energy Technology subModel, ETM) for simulating the power sector, which then provides feedback to the energy demand equations and the whole economy. The ETM submodel uses a probabilistic approach and historical data for estimating the penetration levels of the different technologies, considering their economic, technical and environmental characteristics. Three pathway scenarios (CFH, CLC and CAM) simulate the CO 2 reduction by 40%, 60% and 80% by 2050 compared to 1990 levels respectively and are compared with a reference scenario (REF), with no reduction target. The targets are modeled as the UK contribution to an international mitigation effort, such as achieving the G8 reduction targets, which is a more realistic political framework for the UK to move towards deep reductions rather than moving alone. This paper aims to provide modeling evidence that deep reduction targets can be met through different carbon pathways while also assessing the macroeconomic effects of the pathways on GDP and investment.

Rare earth activated yttrium aluminate phosphors with modulated luminescence.

Science.gov (United States)

Muresan, L E; Popovici, E J; Perhaita, I; Indrea, E; Oro, J; Casan Pastor, N

2016-06-01

Yttrium aluminate (Y3 A5 O12 ) was doped with different rare earth ions (i.e. Gd(3+) , Ce(3+) , Eu(3+) and/or Tb(3+) ) in order to obtain phosphors (YAG:RE) with general formula,Y3-x-a Gdx REa Al5 O12 (x = 0; 1.485; 2.97 and a = 0.03). The synthesis of the phosphor samples was done using the simultaneous addition of reagents technique. This study reveals new aspects regarding the influence of different activator ions on the morpho-structural and luminescent characteristics of garnet type phosphor. All YAG:RE phosphors are well crystallized powders containing a cubic-Y3 Al5 O12 phase as major component along with monoclinic-Y4 Al2 O9 and orthorhombic-YAlO3 phases as the impurity. The crystallites dimensions of YAG:RE phosphors vary between 38 nm and 88 nm, while the unit cell slowly increase as the ionic radius of the activator increases. Under UV excitation, YAG:Ce exhibits yellow emission due to electron transition in Ce(3+) from the 5d level to the ground state levels ((2) F5/2 , (2) F7/2 ). The emission intensity of Ce(3+) is enhanced in the presence of the Tb(3+) ions and is decreased in the presence of Eu(3+) ions due to some radiative or non-radiative processes that take place between activator ions. By varying the rare earth ions, the emission colour can be modulated from green to white and red. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Characterization of metallic surfaces in phosphorous-bronze ordered packings

International Nuclear Information System (INIS)

Sandru, Claudia; Titescu, Gh.

1997-01-01

Copper and its alloys, particularly the phosphorous bronze, are characterized by a high water wettability as compared with other materials. This feature led to utilization of phosphorous bronze in fabrication of contact elements, a packing type equipping the distillation columns. For heavy water separation by isotopic distillation under vacuum, ordered packings of phosphorous bronze networks were fabricated. The superior performances of these packings are determined by the material and also by the geometrical form and the state of the metallic surface. Thus, a procedure of evaluating the wettability has been developed, based on tests of the network material. The results of the tests constitute a criterion of rating the functional performances of packings, particularly of their efficiencies. Also, investigation techniques of the chemical composition and of the thickness of superficial layer on the packing were developed. It was found that the packing surface presents a layer of about 5-20 μm formed mainly by oxides of copper, tin, and, depending on the packing treatment, of oxides of other elements coming from the treatment agent. The paper presents characterization of phosphorous bronze treated with potassium permanganate, a specific treatment for improving the functional performances of the packings used in the heavy water concentration and re-concentration installations

Studies on Y{sub 2}SiO{sub 5}:Ce phosphors prepared by gel combustion using new fuels

Energy Technology Data Exchange (ETDEWEB)

Muresan, L.E., E-mail: laura_muresan2003@yahoo.com [“Raluca Ripan” Institute for Research in Chemistry, Babeş Bolyai University, Fântânele 30, 400294 Cluj-Napoca (Romania); Oprea, B.F.; Cadis, A.I.; Perhaita, I. [“Raluca Ripan” Institute for Research in Chemistry, Babeş Bolyai University, Fântânele 30, 400294 Cluj-Napoca (Romania); Ponta, O. [Faculty of Physics, Babeş Bolyai University, 400084 Cluj-Napoca (Romania)

2014-12-05

Highlights: • Y{sub 2}SiO{sub 5}:Ce was prepared by combustion using aspartic or glutamic acid as fuels. • Combustion process occurs differently depending on the fuels amount. • Single phase X2-Y{sub 2}SiO{sub 5} phosphors were obtained in fuel rich conditions. • PL measurements indicate that aspartic acid is a better fuel than glutamic. • Optimal preparative conditions were established for synthesis of Y{sub 2}SiO{sub 5}:Ce. - Abstract: Cerium activated yttrium silicate (Y{sub 2}SiO{sub 5}:Ce) phosphors were prepared by combustion, using yttrium–cerium nitrate as oxidizer, aspartic or glutamic acid as fuel and TEOS as source of silicon. In this study, aspartic and glutamic acid are used for the first time for the synthesis of Y{sub 2}SiO{sub 5}:Ce phosphors. The fuels molar amount was varied from 0.5 mol to 1.5 mol in order to reveal the thermal behavior of intermediary products (gels and ashes) same as the structural and luminescent characteristics of final products (phosphors). According to thermal analysis correlated with FTIR and XPS investigations, the combustion process occurs differently depending on the fuel amount; unreacted nitrate compounds have been identified in fuel lean conditions and carbonate based compounds along with organic residue in rich fuel conditions. The conversion to well crystallized silicates was revealed by changes of FTIR vibration bands and confirmed by XRD measurements. Based on luminescent spectra, aspartic acid is a better fuel than glutamic acid. A positive effect on the luminescence have been observed for samples fired in air due to complete remove of organic residue. The best luminescence was obtained for combustions with 0.75 mol aspartic acid and 1.25 mol glutamic respectively, fired at 1400 °C for 4 h in air atmosphere.

Synthesis and characterization of Sr2CeO4: Eu3+ phosphor by different forms

International Nuclear Information System (INIS)

Murthy, K.V.R.; Rao, Ch. Atchyutha; Suresh, K.; Ratna Kumar, B.W.; Nageswara Rao, B.; Poornachandra Rao, N.V.; Subba Rao, B.

2011-01-01

High temperature solid state reaction method was explored to synthesize undoped Sr 2 CeO 4 and Eu 3+ RE doped Sr 2 CeO 4 phosphor using inorganic materials taking in three different forms like, form (i) Strontium Carbonate (SrCO 3 ), Cerium Oxide (CeO 2 ), (ii) Strontium Nitrate (Sr(NO 3 ) 2 ), Cerium Oxide (CeO 2 ) and (iii) Strontium Nitrate (Sr(NO 3 ) 2 ), Cerium Nitrate (Ce(NO 3 ) 3 .6(NH 2 .CO.NH 2 ) in stoichiometric proportions of Sr:Ce as 2:1 and ground into a fine powder using agate mortar and pestle about an hour. The grounded samples were placed in an alumina crucible and fired at 1200 deg C for 3 hours in a muffle furnace with a heating rate of 5 deg C/min. To investigate the crystal structure, phase, morphology and luminescent properties of the synthesized phosphors XRD, SEM, Photoluminescence (PL) spectra, TL and CIE techniques were used. The Photoluminescence (PL) emission and excitation spectra were measured by Spectrofluorophotometer (SHIMADZU, RF-5301 PC) using Xenon lamp as excitation source. To identify the crystal phase, XRD analysis was carried out with a powder diffractometer (Rigaku-D/max 2500) using CuKα radiation. The microstructures of the samples were studied using a scanning electron microscopy (SEM) (XL 30 CP Philips). All the analysis was recorded at room temperature. We have compared the results of the prepared samples by different forms. From the XRD analysis it was found that the prepared phosphors are mostly in single phase of Sr 2 CeO 4 with an orthorhombic structure. From the XRD data, using Scherrer's formula the calculated average crystallite size is (i) ∼ 28 nm (ii) ∼ 9 nm (iii) ∼ 7 nm using FWHM. This indicates that, the prepared phosphors via high temperature solid state reaction method is in nano size. Sr 2 CeO 4 exhibits photoluminescence due to the charge transfer (CT) mechanism. The sample displays a broad excitation spectrum range from ∼ 220 to 400 nm. Under 350 nm excitation, the undoped Sr 2 CeO 4 shows

Study of some thermoluminescent phosphors for the dosimetry of ionizing radiations

International Nuclear Information System (INIS)

Jaafari, M.

1983-01-01

Thermoluminescence dosimetry techniques are reviewed and interactions radiation matter are recalled. The need for new phosphors is evidenced. Numerous phosphors are examined and calcium, strontium and barium sulfides are synthetized and deposited on glass supports. The thermoluminescence of the dosimeters obtained with these materials is analyzed [fr

High nitrate to phosphorus regime attenuates negative effects of rising pCO2 on total population carbon accumulation

Directory of Open Access Journals (Sweden)

S. A. Krug

2012-03-01

Full Text Available The ongoing rise in atmospheric pCO2 and consequent increase in ocean acidification have direct effects on marine calcifying phytoplankton, which potentially alters carbon export. To date it remains unclear, firstly, how nutrient regime, in particular by coccolithophores preferred phosphate limitation, interacts with pCO2 on particulate carbon accumulation; secondly, how direct physiological responses on the cellular level translate into total population response. In this study, cultures of Emiliania huxleyi were full-factorially exposed to two different N:P regimes and three different pCO2 levels. Cellular biovolume and PIC and POC content significantly declined in response to pCO2 in both nutrient regimes. Cellular PON content significantly increased in the Redfield treatment and decreased in the high N:P regime. Cell abundance significantly declined in the Redfield and remained constant in the high N:P regime. We hypothesise that in the high N:P regime severe phosphorous limitation could be compensated either by reduced inorganic phosphorous demand and/or by enzymatic uptake of organic phosphorous. In the Redfield regime we suggest that enzymatic phosphorous uptake to supplement enhanced phosphorous demand with pCO2 was not possible and thus cell abundance declined. These hypothesised different physiological responses of E. huxleyi among the nutrient regimes significantly altered population carrying capacities along the pCO2 gradient. This ultimately led to the attenuated total population response in POC and PIC content and biovolume to increased pCO2 in the high N:P regime. Our results point to the fact that the physiological (i.e. cellular PIC and POC response to ocean acidification cannot be linearly extrapolated to total population response and thus carbon export. It is therefore necessary to consider both effects of nutrient limitation on cell physiology and their consequences for population size when predicting the influence of

Renal cysteine conjugate C-S lyase mediated toxicity of halogenated alkenes in primary cultures of human and rat proximal tubular cells.

Science.gov (United States)

McGoldrick, Trevor A; Lock, Edward A; Rodilla, Vicente; Hawksworth, Gabrielle M

2003-07-01

Proximal tubular cells from human (HPT) and rat (RPT) kidneys were isolated, grown to confluence and incubated with S-(1,2-dichlorovinyl)- l-cysteine (DCVC), S-(1,2,2-trichlorovinyl)- l-cysteine (TCVC), S-(1,1,2,2-tetrafluoroethyl)- l-cysteine (TFEC) and S-(2-chloro-1,1-difluorethyl)- l-cysteine (CDFEC), the cysteine conjugates of nephrotoxicants. The cultures were exposed to the conjugates for 12, 24 and 48 h and the toxicity determined using the MTT assay. All four conjugates caused dose-dependent toxicity to RPT cells over the range 50-1,000 microM, the order of toxicity being DCVC>TCVC>TFEC=CDFEC. The inclusion of aminooxyacetic acid (AOAA; 250 microM), an inhibitor of pyridoxal phosphate-dependent enzymes such as C-S lyase, afforded protection, indicating that C-S lyase has a role in the bioactivation of these conjugates. In HPT cultures only DCVC caused significant time- and dose-dependent toxicity. Exposure to DCVC (500 microM) for 48 h decreased cell viability to 7% of control cell values, whereas co-incubation of DCVC (500 microM) with AOAA (250 microM) resulted in cell viability of 71%. Human cultures were also exposed to S-(1,2-dichlorovinyl)-glutathione (DCVG). DCVG was toxic to HPT cells, but the onset of toxicity was delayed compared with the corresponding cysteine conjugate. AOAA afforded almost complete protection from DCVG toxicity. Acivicin (250 microM), an inhibitor of gamma-glutamyl transferase (gamma-GT), partially protected against DCVG (500 microM)-induced toxicity at 48 h (5% viability and 53% viability in the absence and presence of acivicin, respectively). These results suggest that DCVG requires processing by gamma-GT prior to bioactivation by C-S lyase in HPT cells. The activity of C-S lyase, using TFEC as a substrate, and glutamine transaminase K (GTK) was measured in rat and human cells with time in culture. C-S lyase activity in RPT and HPT cells decreased to approximately 30% of fresh cell values by the time the cells reached

Abundance and genetic diversity of microbial polygalacturonase and pectate lyase in the sheep rumen ecosystem.

Directory of Open Access Journals (Sweden)

Peng Yuan

Full Text Available Efficient degradation of pectin in the rumen is necessary for plant-based feed utilization. The objective of this study was to characterize the diversity, abundance, and functions of pectinases from microorganisms in the sheep rumen.A total of 103 unique fragments of polygalacturonase (PF00295 and pectate lyase (PF00544 and PF09492 genes were retrieved from microbial DNA in the rumen of a Small Tail Han sheep, and 66% of the sequences of these fragments had low identities (<65% with known sequences. Phylogenetic tree building separated the PF00295, PF00544, and PF09492 sequences into five, three, and three clades, respectively. Cellulolytic and noncellulolytic Butyrivibrio, Prevotella, and Fibrobacter species were the major sources of the pectinases. The two most abundant pectate lyase genes were cloned, and their protein products, expressed in Escherichia coli, were characterized. Both enzymes probably act extracellularly as their nucleotide sequences contained signal sequences, and they had optimal activities at the ruminal physiological temperature and complementary pH-dependent activity profiles.This study reveals the specificity, diversity, and abundance of pectinases in the rumen ecosystem and provides two additional ruminal pectinases for potential industrial use under physiological conditions.

Expression and enzymatic activity of phenylalanine ammonia-lyase and p-coumarate 3-hydroxylase in mango (Mangifera indica 'Ataulfo') during ripening.

Science.gov (United States)

Palafox-Carlos, H; Contreras-Vergara, C A; Muhlia-Almazán, A; Islas-Osuna, M A; González-Aguilar, G A

2014-05-16

Phenylalanine ammonia lyase (PAL) and p-coumarate 3-hydroxylase (C3H) are key enzymes in the phenylpropanoid pathway. The relative expression of PAL and C3H was evaluated in mango fruit cultivar 'Ataulfo' in four ripening stages (RS1, RS2, RS3, and RS4) by quantitative polymerase chain reaction. In addition, enzyme activity of PAL and C3H was determined in mango fruits during ripening. The PAL levels were downregulated at the RS2 and RS3 stages, while C3H levels were upregulated in fruits only at RS3. The enzyme activity of PAL followed a pattern that was different from that of the PAL expression, thus suggesting regulation at several levels. For C3H, a regulation at the transcriptional level is suggested because a similar pattern was revealed by its activity and transcript level. In this study, the complexity of secondary metabolite biosynthesis regulation is emphasized because PAL and C3H enzymes are involved in the biosynthesis of several secondary metabolites that are active during all mango ripening stages.

Complexity in Acid–Base Titrations: Multimer Formation Between Phosphoric Acids and Imines

Science.gov (United States)

Malm, Christian; Kim, Heejae; Wagner, Manfred

2017-01-01

Abstract Solutions of Brønsted acids with bases in aprotic solvents are not only common model systems to study the fundamentals of proton transfer pathways but are also highly relevant to Brønsted acid catalysis. Despite their importance the light nature of the proton makes characterization of acid–base aggregates challenging. Here, we track such acid–base interactions over a broad range of relative compositions between diphenyl phosphoric acid and the base quinaldine in dichloromethane, by using a combination of dielectric relaxation and NMR spectroscopy. In contrast to what one would expect for an acid–base titration, we find strong deviations from quantitative proton transfer from the acid to the base. Even for an excess of the base, multimers consisting of one base and at least two acid molecules are formed, in addition to the occurrence of proton transfer from the acid to the base and simultaneous formation of ion pairs. For equimolar mixtures such multimers constitute about one third of all intermolecular aggregates. Quantitative analysis of our results shows that the acid‐base association constant is only around six times larger than that for the acid binding to an acid‐base dimer, that is, to an already protonated base. Our findings have implications for the interpretation of previous studies of reactive intermediates in organocatalysis and provide a rationale for previously observed nonlinear effects in phosphoric acid catalysis. PMID:28597513

Complexity in Acid-Base Titrations: Multimer Formation Between Phosphoric Acids and Imines.

Science.gov (United States)

Malm, Christian; Kim, Heejae; Wagner, Manfred; Hunger, Johannes

2017-08-10

Solutions of Brønsted acids with bases in aprotic solvents are not only common model systems to study the fundamentals of proton transfer pathways but are also highly relevant to Brønsted acid catalysis. Despite their importance the light nature of the proton makes characterization of acid-base aggregates challenging. Here, we track such acid-base interactions over a broad range of relative compositions between diphenyl phosphoric acid and the base quinaldine in dichloromethane, by using a combination of dielectric relaxation and NMR spectroscopy. In contrast to what one would expect for an acid-base titration, we find strong deviations from quantitative proton transfer from the acid to the base. Even for an excess of the base, multimers consisting of one base and at least two acid molecules are formed, in addition to the occurrence of proton transfer from the acid to the base and simultaneous formation of ion pairs. For equimolar mixtures such multimers constitute about one third of all intermolecular aggregates. Quantitative analysis of our results shows that the acid-base association constant is only around six times larger than that for the acid binding to an acid-base dimer, that is, to an already protonated base. Our findings have implications for the interpretation of previous studies of reactive intermediates in organocatalysis and provide a rationale for previously observed nonlinear effects in phosphoric acid catalysis. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Ultraviolet dosimetry using thermoluminescent phosphors - an update

International Nuclear Information System (INIS)

Nagpal, J.S.

1998-04-01

Intrinsic response of various thermoluminescent (TL) materials such as CaSO 4 (Dy, Eu, Mn, Sm, Tb, or Tm), LiF (Mg, Cu, P), Mg 2 SiO 4 :Tb, CaF 2 :Dy, CaF 2 :Tb, ThO 2 :Tb and Al 2 O 3 (Si, Ti); cathodoluminescent phosphors Y 3 Al 5 O 12 :Ce, Y 3 Al 5 O 12 :Tb and Y(V,P)O 4 :Eu; and fluorescent lamp phosphors calcium halophosphate (Mn,Sb) and Ce Mg aluminate (Eu, Tb) to ultraviolet (UV) radiations has been studied. Intrinsic TL response of most of the phosphors is rate (radiant flux) dependent. For the first time, UV response of the materials is reported for a fixed total radiant energy (total UV dose), at a single radiant flux (260 μW.cm -2 ), for an appropriate comparison. A wide range of UV sensitivity is observed. Studies conducted using UV radiation from two unfiltered low pressure mercury lamps show significant differences in glow curves, as compared to those obtained with nearly monochromatic UV radiations. Photons of wavelength 365 nm induce bleaching of TL induced by 254 nm photons, in most of the materials. Sequential/tandem exposures to 254 nm and 365 nm photons have yielded new but alarming results in CaF 2 :Tb. Preferential induction and bleaching of specific TL glow peaks by 365 nm and 254 nm photons are interesting characteristics discovered in CaSO 4 :Eu. Photoluminescence studies of Tb 3+ and Eu 3+ activated phosphors have augmented the inferences drawn from the bleaching effects produced by 365 nm photons. Earlier work carried out on phototransferred thermoluminescence of CaSO 4 :Dy-teflon dosimeters, TLD-100, Mg 2 SiO 4 :Tb and Al 2 O 3 (Si,Ti) has also been reviewed. (author)

Oxidation-extraction of uranium from wet-process phosphoric acid

International Nuclear Information System (INIS)

Lawes, B.C.

1985-01-01

The invention involves an improvement to the reductive stripping process for recovering uranium values from wet-process phosphoric acid solution, where uranium in the solution is oxidized to uranium (VI) oxidation state and then extracted from the solution by contact with a water immiscible organic solvent, by adding sufficient oxidant, hydrogen peroxide, to obtain greater than 90 percent conversion of the uranium to the uranium (VI) oxidation state to the phosphoric acid solution and simultaneously extracting the uranium (VI)

Radionuclide concentrations in raw and purified phosphoric acids from Brazil and their processing wastes: implications for radiation exposures.

Science.gov (United States)

da Conceição, Fabiano Tomazini; Antunes, Maria Lúcia Pereira; Durrant, Steven F

2012-02-01

Radionuclides from the U and Th natural series are present in alkaline rocks, which are used as feedstock in Brazil for the production of raw phosphoric acid, which can be considered as a NORM (naturally occurring radioactive material). As a result of the purification of raw phosphoric acid to food-grade phosphoric acid, two by-products are generated, i.e., solid and liquid wastes. Taking this into account, the main aim of this study was to evaluate the fluxes of natural radionuclide in the production of food-grade phosphoric acids in Brazil, to determine the radiological impact caused by ingestion of food-grade phosphoric acid, and to evaluate the solid waste environmental hazards caused by its application in crop soils. Radiological characterization of raw phosphoric acid, food-grade phosphoric acid, solid waste, and liquid waste was performed by alpha and gamma spectrometry. The (238)U, (234)U, (226)Ra, and (232)Th activity concentrations varied depending on the source of raw phosphoric acid. Decreasing radionuclides activity concentrations in raw phosphoric acids used by the producer of the purified phosphoric acid were observed as follows: Tapira (raw phosphoric acid D) > Catalão (raw phosphoric acids B and C) > Cajati (raw phosphoric acid A). The industrial purification process produces a reduction in radionuclide activity concentrations in food-grade phosphoric acid in relation to raw phosphoric acid produced in plant D and single raw phosphoric acid used in recent years. The most common use of food-grade phosphoric acid is in cola soft drinks, with an average consumption in Brazil of 72 l per person per year. Each liter of cola soft drink contains 0.5 ml of food-grade phosphoric acid, which gives an annual average intake of 36 ml of food-grade phosphoric acid per person. Under these conditions, radionuclide intake through consumption of food-grade phosphoric acid per year per person via cola soft drinks is not hazardous to human health in Brazil

Novel Br-DPQ blue light-emitting phosphors for OLED.

Science.gov (United States)

Dahule, H K; Thejokalyani, N; Dhoble, S J

2015-06-01

A new series of blue light-emitting 2,4-diphenylquinoline (DPQ) substituted blue light-emitting organic phosphors namely, 2-(4-methoxy-phenyl)-4-phenyl-quinoline (OMe-DPQ), 2-(4-methyl-phenyl)-4-phenylquinoline (M-DPQ), and 2-(4-bromo-phenyl)-4-phenylquinoline (Br-DPQ) were synthesized by substituting methoxy, methyl and bromine at the 2-para position of DPQ, respectively by Friedländer condensation of 2-aminobenzophenone and corresponding acetophenone. The synthesized phosphors were characterized by different techniques, e.g., Fourier transform infra-red (FTIR), differential scanning calorimeter (DSC), UV-visible absorption and photoluminescence spectra. FTIR spectra confirms the presence of chemical groups such as C=O, NH, or OH in all the three synthesized chromophores. DSC studies show that these complexes have good thermal stability. Although they are low-molecular-weight organic compounds, they have the potential to improve the stability and operating lifetime of a device made out of these complexes. The synthesized polymeric compounds demonstrate a bright emission in the blue region in the wavelength range of 405-450 nm in solid state. Thus the attachment of methyl, methoxy and bromine substituents to the diphenyl quinoline ring in these phosphors results in colour tuning of the phosphorescence. An electroluminescence (EL) cell of Br-DPQ phosphor was made and its EL behaviour was studied. A brightness-voltage characteristics curve of Br-DPQ cell revealed that EL begins at 400 V and then the brightness increases exponentially with applied AC voltage, while current-voltage (I-V) characteristics revealed that the turn on voltage of the fabricated EL cell was 11 V. Hence this phosphor can be used as a promising blue light material for electroluminescent devices. Copyright © 2014 John Wiley & Sons, Ltd.

[The spectrogram characteristics of organic blue-emissive light-emitting excitated YAG : Ce phosphor].

Science.gov (United States)

Xi, Jian-Fei; Zhang, Fang-Hui; Mu, Qiang; Zhang, Mai-Li

2011-09-01

It is demonstrated that the panchromatic luminescence devices with organic blue-emissive light-emitting was fabricated. This technique used down conversion, which was already popular in inorganic power LEDs to obtain white light emission. A blue OLED device with a configuration of ITO/2T-NATA (30 nm)/AND : TBPe (50 Wt%, 40 nm)/Alq3 (100 nm)/LiF(1 nm)/Al(100 nm) was prepared via vacuum deposition process, and then coated with YAG : Ce phosphor layers of different thicknesses to obtain a controllable and uniform shape while the CIE coordinates were fine tuned. This development not only decreased steps of technics and degree of difficulty, but also applied the mature technology of phosphor. The results showed that steady spectrogram was obtained in the devices with phosphor, with a best performance of a maximum luminance of 13 840 cd x m(-2) which was about 2 times of that of the devices without phosphor; a maximum current efficiency of 17.3 cd x A(-1) was increased more two times more than the devices without phosphor. The emission spectrum could be adjusted by varying the concentration and thickness of the phosphor layers. Absoulte spectrogram of devices was in direct proportion with different driving current corresponding.

TL process in europium doped alkaline earth sulphate phosphors- a review

International Nuclear Information System (INIS)

Bhatt, B.C.

2003-01-01

CaSO 4 doped with the rare earth (RE) ion dysprosium or thulium is used routinely as a thermoluminescent dosimeter (TLD) to monitor personal exposure to x- and γ-radiation. The CaSO 4 :Eu phosphor is potentially important for radio photoluminescence (RPL) and ultraviolet (UV) dosimetry. Eu 3+ → Eu 2+ conversion is suggested to play a pivotal role in UV and γ-ray induced thermoluminescence. However, there is disagreement among different workers on the mechanism of gamma and UV induced TL in this phosphor system. This paper will review the work reported on CaSO 4 :Eu and make effects to project overall picture on this phosphor system. (author)

Engineering of Saccharomyces cerevisiae for production of resveratrol and its derivatives

DEFF Research Database (Denmark)

Li, Mingji

were published in Applied and Environmental Microbiology (Jendresen et al., 2015). I then constructed the TAL pathway to resveratrol by expressing the two TAL genes in combination with 4-coumaryl-CoA ligase (4CL) from Arabidopsis thaliana and resveratrol synthase (VST) from Vitis vinifera in S...... carbon sources. I adopted rational metabolic engineering rational design strategies, synthetic biology techniques and system biology approaches to engineer and analyse yeast cell factories. There are two biosynthesis pathways of resveratrol, starting from tyrosine or phenylalanine, which in this thesis...... are defined as the TAL pathway and PAL pathway respectively. For the TAL pathway, I collaborated with Christian Bille Jendresen, Steen Gustav Stahlhut to screen fourteen diverse heterologous tyrosine ammonia lyases (TALs) for their activity in yeast and E. coli. I expressed the 14 TALs in S. cerevisiae...

Determination of the activity concentration of 230Th in phosphoric acids produced in Brazil

International Nuclear Information System (INIS)

Taddei, M.H.T.; Ferreira, M.T.; Fukuma, H.T.; Xavier, T.T.; Sousa, F.V.T.S.

2017-01-01

The high uranium phosphate rock from Itataia, Brazil, was processed using the wet route in the dihydrate system to manufacture phosphoric acid. The uranium contained in phosphoric acid was recovered by the solvent extraction technique. The distribution of the long half-life radionuclides from the decay series of 238 U and 232 Th were evaluated in these processes. The 26 Ra, 228 Ra and 210 Pb radionuclides were found predominantly in phosphogypsum, while the isotopes of 228 Th, 230 Th and 232 Th predominated in phosphoric acid after extracting uranium. The main concern in the commercialization of phosphoric acid that will be produced in the Itataia plant is in relation to the content of 230 Th. This work determined the content of these radionuclides in phosphoric acid from different locations in the country in order to compare

Boron-Containing Red Light-Emitting Phosphors And Light Sources Incorporating The Same

Science.gov (United States)

Srivastava, Alok Mani; Comanzo, Holly Ann; Manivannan, Venkatesan

2006-03-28

A boron-containing phosphor comprises a material having a formula of AD1-xEuxB9O16, wherein A is an element selected from the group consisting of Ba, Sr, Ca, Mg, and combinations thereof; D is at least an element selected from the group consisting of rare-earth metals other than europium; and x is in the range from about 0.005 to about 0.5. The phosphor is used in a blend with other phosphors in a light source for generating visible light with a high color rendering index.

Eu/Tb ions co-doped white light luminescence Y2O3 phosphors

International Nuclear Information System (INIS)

Tu Dong; Liang Yujun; Liu Rong; Li Daoyi

2011-01-01

Y 2 O 3 :Eu 3+ , Tb 3+ phosphors with white emission are prepared with different doping concentration of Eu 3+ and Tb 3+ ions and synthesizing temperatures from 750 to 950 deg. C by the co-precipitation method. The resulted phosphors were characterized by X-ray diffraction (XRD) and photoluminescence (PL) spectroscopy. The results of XRD indicate that the crystallinity of the synthesized samples increases with enhancing the firing temperature. The photoluminescence spectra indicate the Eu 3+ and Tb 3+ co-doped Y 2 O 3 phosphors show five main emission peaks: three at 590, 611 and 629 nm originate from Eu 3+ and two at 481 and 541 nm originate from Tb 3+ , under excitation of 250-320 nm irradition. The white light luminescence color could be changed by varying the excitation wavelength. Different concentrations of Eu 3+ and Tb 3+ ions were induced into the Y 2 O 3 lattice and the energy transfer from Tb 3+ →Eu 3+ ions in these phosphors was found. The Commission International de l'Eclairage (CIE) chromaticity shows that the Y 2 O 3 :Eu 3+ , Tb 3+ phosphors can obtain an intense white emission. - Highlights: → Novel phosphors Y 2 O 3 :Eu 3+ , Tb 3+ have been synthesized by co-precipitation method. → Samples emit white light with excellent color coordinates under UV excitation. → Luminescence color could be changed by varying the excitation wavelength. → Energy transfer from Tb 3+ →Eu 3+ ions in these phosphors was found.

Phosphors containing boron and metals of Group IIIA and IIIB

Science.gov (United States)

Setlur, Anant Achyut; Srivastava, Alok Mani; Comanzo, Holly Ann; Manivannan, Venkatesan

2006-10-31

A phosphor comprises: (a) at least a first metal selected from the group consisting of yttrium and elements of lanthanide series other than europium; (b) at least a second metal selected from the group consisting of aluminum, gallium, indium, and scandium; (c) boron; and (d) europium. The phosphor is used in light source that comprises a UV radiation source to convert UV radiation to visible light.

Thermoluminescence dosimetric characteristics of thulium doped ZnB{sub 2}O{sub 4} phosphor

Energy Technology Data Exchange (ETDEWEB)

Annalakshmi, O. [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Jose, M.T., E-mail: mtj@igcar.gov.in [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Madhusoodanan, U. [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Subramanian, J. [Central Leather Research Institute, Council of Scientific and Industrial Research, Chennai (India); Venkatraman, B. [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Amarendra, G. [Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Mandal, A.B. [Central Leather Research Institute, Council of Scientific and Industrial Research, Chennai (India)

2014-02-15

Polycrystalline powder samples of rare earth doped Zinc borates were synthesized by high temperature solid state diffusion technique. Dosimetric characteristics of the phosphor like thermoluminescence glow curve, TL emission spectra, dose–response, fading studies, reproducibility and reusability studies were carried out on the synthesized phosphors. Among the different rare earth doped phosphors, thulium doped zinc borate was found to have a higher sensitivity. Hence detailed dosimetric characteristics of this phosphor were carried out. It is observed that the dose–response is linear from 10 mGy to 10{sup 3} Gy in this phosphor. EPR measurements were carried out on unirradiated, gamma irradiated and annealed phosphors to identify the defect centers responsible for thermoluminescence. A TL model is proposed based on the EPR studies in these materials. Kinetic parameters were evaluated for the dosimetric peaks using various methods. The experimental results show that this phosphor can have potential applications in radiation dosimetry applications. -- Highlights: • Polycrystalline powder samples of rare earth doped zinc borates were synthesized. • Thulium was observed to be the most efficient dopant in ZnB{sub 2}O{sub 4} lattice. • TL intensity of the dosimetric peak is around 20 times that of TLD-100. • Based on EPR studies a TL mechanism is proposed in zinc borate. • Deconvolution of the glow curve carried out.

The anaerobic chytridiomycete fungus Piromyces sp. E2 produces ethanol via pyruvate:formate lyase and an alcohol dehydrogenase E.

NARCIS (Netherlands)

Boxma, B.; Voncken, F.L.M.; Jannink, S.A.; Alen, T.A. van; Akhmanova, A.S.; Weelden, S.W. van; Hellemond, J.J. van; Ricard, G.N.S.; Huynen, M.A.; Tielens, A.G.; Hackstein, J.H.P.

2004-01-01

Anaerobic chytridiomycete fungi possess hydrogenosomes, which generate hydrogen and ATP, but also acetate and formate as end-products of a prokaryotic-type mixed-acid fermentation. Notably, the anaerobic chytrids Piromyces and Neocallimastix use pyruvate:formate lyase (PFL) for the catabolism of

Transport of phosphoric acid through supported liquid membrane

International Nuclear Information System (INIS)

Zayzafoon, G.; Yassine, T.; Baidoun, R.

2003-01-01

The transport of phosphhoric acid through liquid membranes of amylalkohol, 1-octanol and 2-octanol was studied. It was found that phosphoric acid is transfered from feed side to strip side and the transport increased with the concentration of phosphoric acid up to 5M. The permeability in each membrane was determined for 5M phosphoic acid. It was found that the permeability values are 1.45 x 10 1 0 m 2 s 1 for amylakohol and ∼ 1x10 1 0 m 2 s 1 for each of 1-octanol and 2-octanol

Photoluminescence in Sm3+ doped Ba2P2O7 phosphor prepared by solution combustion method

Science.gov (United States)

Ghawade, Sonal P.; Deshmukh, Kavita A.; Dhoble, S. J.; Deshmukh, Abhay D.

2018-05-01

In this paper, Sm3+ doped Ba2P2O7 phosphors were synthesized via a Solution combustion method. The crystal structure of the phosphor was characterized by XRD. Orange-red emission was observed from these phosphors under near-ultraviolet (UV) excitation at 404 nm. The luminescence properties of the obtained phosphors were characterized by different techniques. The Ba2P2O7:Sm3+ phosphor can be efficiently excited by near-UV and blue light, and their emission spectrum consists of three emission peaks, at 564, 602, and 646 nm, respectively. Based on the results, the as prepared Ba2P2O7:Sm3+ phosphors are promising orange-red-emitting phosphors exhibit great potential may be applicable as a spectral convertor in c-Si solar cell to enhance the efficiency of solar cell in future.

Fatty acid hydroperoxides pathways in plants. A review.

Directory of Open Access Journals (Sweden)

Fauconnier, M. L.

1997-02-01

Full Text Available The present paper focusses on the fatty acid hydroperoxides pathways, mainly hydroperoxide lyase and hydroperoxide dehydrase. For each enzyme, the definition, occurrence and subcellular localization is presented. Particular attention is given to reaction mecanisms and to substrate specificity. Physiological roles of reaction products are also discussed.

El presente artículo se centra en las rutas de los hidroperóxidos de ácidos grasos, principalmente la hidroperóxido liasa y la hidroperóxido dehidrasa. Se presenta para cada enzima, la definición, distribución y localización subcelular. Se da atención particular a los mecanismos de reacción y a la especificidad de sustrato. También se discuten los papeles fisiológicos de los productos de reacción.

Identification, expression, and characterization of a novel bacterial RGI Lyase enzyme for the production of bio-functional fibers

DEFF Research Database (Denmark)

da Silva, Ines Isabel Cardoso Rodrigues; Larsen, Dorte Møller; Meyer, Anne S.

2011-01-01

A gene encoding a putative rhamnogalacturonan I (RGI) Lyase (EC 4.2.2.-) from Bacillus licheniformis (DSM13) was selected after a homology search and phylogenetic analysis and optimized with respect to codon usage. The designed gene was transformed into Pichia pastoris and the enzyme was produced...

Activated phosphors having matrices of yttrium-transition metal compound

International Nuclear Information System (INIS)

De Kalb, E.L.; Fassel, V.A.

1975-01-01

A method is described for preparing a phosphor composition containing a lanthanide activator element with a host matrix having a transition element as a major component. The host matrix is composed of certain rare earth phosphates or vanadates such as YPO 4 with a portion of the rare earth replaced with one or more of the transition elements. On x-ray or other electromagnetic excitation, trace lanthanide impurities or additives within the phosphor are spectrometrically determined from their characteristic luminescence

Pentose pathway in human liver

International Nuclear Information System (INIS)

Magnusson, I.; Chandramouli, V.; Schumann, W.C.; Kumaran, K.; Wahren, J.; Landau, B.R.

1988-01-01

[1- 14 C]Ribose and [1- 14 C]glucose were given to normal subjects along with glucose loads (1 g per kg of body weight) after administration of diflunisal and acetaminophen, drugs that are excreted in urine as glucuronides. Distributions of 14 C were determined in the carbons of the excreted glucoronides and in the glucose from blood samples drawn from hepatic veins before and after glucagon administration. Eighty percent or more of the 14 C from [1- 14 C]ribose incorporated into the glucuronic acid moiety of the glucuronides was in carbons 1 and 3, with less than 8% in carbon 2. In glucuronic acid from glucuronide excreted when [2- 14 C]glucose was given, 3.5-8.1% of the 14 C was in carbon 1, 2.5-4.3% in carbon 3, and more than 70% in carbon 2. These distributions are in accord with the glucuronides sampling the glucose unit of the glucose 6-phosphate pool that is a component of the pentose pathway and is intermediate in glycogen formation. It is concluded that the glucuronic acid conjugates of the drugs can serve as a noninvasive means of sampling hepatic glucose 6-phosphate. In human liver, as in animal liver, the classical pentose pathway functions, not the L-type pathway, and only a small percentage of the glucose is metabolized via the pathway

Luminescence properties of CdSiO3:Mn2+ phosphor

International Nuclear Information System (INIS)

Lei Bingfu; Liu Yingliang; Ye Zeren; Shi Chunshan

2004-01-01

A novel long-lasting phosphor CdSiO 3 :Mn 2+ is reported in this paper. The Mn 2+ -doped CdSiO 3 phosphor emits orange light with CIE chromaticity coordinates x=0.5814 and y=0.4139 under 254 nm UV light excitation. In the emission spectrum of 1% Mn 2+ -doped CdSiO 3 phosphor, there is a broad emission band centered at 575 nm which can be attributed to the spin-forbidden transition of the d-orbital electron associated with the Mn 2+ ion. The phosphorescence can be seen by the naked eyes in the dark clearly even after the 254 nm UV irradiation have been removed for about 1 h. The mechanism of the origin of the long-lasting phosphorescence was discussed using the thermoluminescence curves

Photoluminescence properties of Eu(3+)/ Sm(3+) activated CaZr4(PO4)6 phosphors.

Science.gov (United States)

Nair, Govind B; Dhoble, S J

2016-09-01

Solid state reaction method was employed for the synthesis of a series of CaZr4(PO4)6: Eu(3+)/Sm(3+) phosphors. The red-emitting CaZr4(PO4)6:Eu(3+) phosphors can be efficiently excited at 396 nm and thereby, exhibit a strong red luminescence predominantly corresponding to the electric dipole transition at 615 nm. Under 405 nm excitation, CaZr4(PO4)6:Sm(3+) phosphors display orange emission with color temperatures approximately around 2200 K. The acquired results reveal that CaZr4(PO4)6: RE(3+) (RE = Eu, Sm) phosphors could be potential candidates for red and orange emitting phosphor, respectively, for UV/blue-pump LEDs.

Technology of uranium recovery from wet-process phosphoric acid

Energy Technology Data Exchange (ETDEWEB)

Inoue, Katsutoshi [Saga Univ. (Japan). Faculty of Science and Engineering; Nakashio, Fumiyuki

1982-12-01

Rock phosphate contains from 0.005 to 0.02 wt.% of uranium. Though the content is a mere 5 to 10 % of that in uranium ore, the total recovery of uranium is significant since it is used for fertilizer manufacture in a large quantity. Wet-process phosphoric acid is produced by the reaction of rock phosphate with sulfuric acid. The recovery of uranium from this phosphoric acid is mostly by solvent extraction at present. According to U/sup 4 +/ or UO/sub 2//sup 2 +/ as the form of its existence, the technique of solvent extraction differs. The following matters are described: processing of rock phosphate; recovery techniques including the extraction by OPPA-octyl pyrophosphoric acid for U/sup 4 +/, and by mixed DEHPA-Di-(2)-ethylhexyl phosphoric acid and TOPO-tryoctyl phosphine oxide for UO/sub 2//sup 2 +/, and by OPAP-octylphenyl acid phosphate for U/sup 4 +/; the recent progress of the technology as seen in patents.

Instense red phosphors for UV light emitting diode devices.

Science.gov (United States)

Cao, Fa-Bin; Tian, Yan-Wen; Chen, Yong-Jie; Xiao, Lin-Jiu; Liu, Yun-Yi

2010-03-01

Ca(x)Sr1-x-1.5y-0.5zMoO4:yEu3+ zNa+ red phosphors were prepared by solid-state reaction using Na+ as charge supply for LEDs (light emitting diodes). The content of charge compensator, Ca2+ concentration, synthesis temperature, reaction time, and Eu3+ concentration were the keys to improving the properties of luminescence and crystal structure of red phosphors. The photoluminescence spectra shows the red phosphors are effectively excited at 616 nm by 311 nm, 395 nm, and 465 nm light. The wavelengths of 395 and 465 nm nicely match the widely applied emission wavelengths of ultraviolet or blue LED chips. Its chromaticity coordinates (CIE) are calculated to be x = 0.65, y = 0.32. Bright red light can be observed by the naked eye from the LED-based Ca0.60Sr0.25MoO4:0.08Eu3+ 0.06Na+.

Near-infrared dyes and upconverting phosphors as biomolecule labels and probes

Science.gov (United States)

Patonay, Gabor; Strekowski, Lucjan; Nguyen, Diem-Ngoc; Seok, Kim Jun

2007-02-01

Near-Infrared (NIR) absorbing chromophores have been used in analytical and bioanalytical chemistry extensively, including for determination of properties of biomolecules, DNA sequencing, immunoassays, capillary electrophoresis (CE) separations, etc. The major analytical advantages of these dyes are low background interference and high molar absorptivities. NIR dyes have additional advantages due to their sensitivity to microenvironmental changes. Spectral changes induced by the microenvironment are not desirable if the labels are used as a simple reporting group, e.g., during a biorecognition reaction. For these applications upconverting phosphors seem to be a better choice. There are several difficulties in utilizing upconverting phosphors as reporting labels. These are: large physical size, no reactive groups and insolubility in aqueous systems. This presentation will discuss how these difficulties can be overcome for bioanalytical and forensic applications. During these studies we also have investigated how to reduce physical size of the phosphor by simple grinding without losing activity and how to attach reactive moiety to the phosphor to covalently bind to the biomolecule of interest. It has to be emphasized that the described approach is not suitable for medical applications and the results of this research are not applicable in medical applications. For bioanalytical and forensic applications upconverting phosphors used as reporting labels have several advantages. They are excited with lasers that are red shifted respective to phosphorescence, resulting in no light scatter issues during detection. Also some phosphors are excited using eye safe lasers. In addition energy transfer to NIR dyes is possible, allowing detection schemes using donor-acceptor pairs. Data is presented to illustrate the feasibility of this phenomenon. If microenvironmental sensitivity is required, then specially designed NIR dyes can be used as acceptor labels. Several novel dyes

Why do proton conducting polybenzimidazole phosphoric acid membranes perform well in high-temperature PEM fuel cells?

Science.gov (United States)

Melchior, Jan-Patrick; Majer, Günter; Kreuer, Klaus-Dieter

2016-12-21

Transport properties and hydration behavior of phosphoric acid/(benz)imidazole mixtures are investigated by diverse NMR techniques, thermogravimetric analysis (TGA) and conductivity measurements. The monomeric systems can serve as models for phosphoric acid/poly-benzimidazole membranes which are known for their exceptional performance in high temperature PEM fuel cells. 1 H- and 31 P-NMR data show benzimidazole acting as a strong Brønsted base with respect to neat phosphoric acid. Since benzimidazole's nitrogens are fully protonated with a low rate for proton exchange with phosphate species, proton diffusion and conduction processes must take place within the hydrogen bond network of phosphoric acid only. The proton exchange dynamics between phosphate and benzimidazole species pass through the intermediate exchange regime (with respect to NMR line separations) with exchange times being close to typical diffusion times chosen in PFG-NMR diffusion measurements (ms regime). The resulting effects, as described by the Kärger equation, are included into the evaluation of PFG-NMR data for obtaining precise proton diffusion coefficients. The highly reduced proton diffusion coefficient within the phosphoric acid part of the model systems compared to neat phosphoric acid is suggested to be the immediate consequence of proton subtraction from phosphoric acid. This reduces hydrogen bond network frustration (imbalance of the number of proton donors and acceptors) and therefore also the rate of structural proton diffusion, phosphoric acid's acidity and hygroscopicity. Reduced water uptake, shown by TGA, goes along with reduced electroosmotic water drag which is suggested to be the reason for PBI-phosphoric acid membranes performing better in fuel cells than other phosphoric-acid-containing electrolytes with higher protonic conductivity.

Enhanced red emission of LaVO4:Eu3+ phosphors by Li-doping

International Nuclear Information System (INIS)

Park, Sung Wook; Yang, Hyun Kyoung; Chung, Jong Won; Moon, Byung Kee; Choi, Byung Chun; Jeong, Jung Hyun; Jang, Ki Wan; Lee, Ho Sueb; Yi, Soung Soo

2010-01-01

LaVO 4 phosphors were synthesized by using a solid state reaction, and were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL). The XRD patterns of the Li-doped LaVO 4 :Eu 3+ powder phosphors revealed a mixture of tetragonal and monoclinic phases. The tetragonal phase of the LaVO 4 :Eu 3+ phosphor showed a higher PL intensity than the monoclinic one, despite the presence of both monoclinic and tetragonal structures. The Li-doped LaVO 4 :Eu 3+ powder phosphors absorbed strongly at 396 nm and exhibited strong red emission at approximately 619.5 nm due to the 5 D 0 → 7 F 2 transition. The incorporation of Li + ions into the LaVO 4 :Eu 3+ powder can lead to a remarkable increase in photoluminescence. The enhanced luminescence is attributed to the incorporation of Li + ions that may act as a sensitizers for effective energy transfer. This phosphor has promising applications in near-UV light-emitting diodes(LEDs).

UV excited downconversion luminescence properties of Eu3+: NaZnPO4 phosphors

Science.gov (United States)

Mukhopadhyay, Lakshmi; Rai, Vineet Kumar

2018-05-01

The structural and optical properties of Eu3+: NaZnPO4 phosphors prepared by chemical coprecipitation method have been studied. The phase formation and morphology of the phosphors have been confirmed by the X-ray diffraction (XRD) and Field emission scanning electron microscopy (FESEM) analysis. The downconversion emission spectra upon 392 nm excitation exhibit five emission bands centred at ˜ 575 nm, ˜ 590 nm, ˜ 612 nm, ˜ 660 nm and ˜ 702 nm corresponding to the 5D0→7F0, 5D0→7F1, 5D0→7F2, 5D0→7F3 and 5D0→7F4 transitions of Eu3+ ions respectively. The observed downconversion emission peaks can be explained with the help of suitable energy level diagram. The CIE chromaticity diagram shows the purity of the emitted colour from the prepared phosphors. The present phosphors emit in intense red region which shows the applicability of the phosphors in red light emitting display devices.

Structural optimization for remote white light-emitting diodes with quantum dots and phosphor: packaging sequence matters.

Science.gov (United States)

Xie, Bin; Chen, Wei; Hao, Junjie; Wu, Dan; Yu, Xingjian; Chen, Yanhua; Hu, Run; Wang, Kai; Luo, Xiaobing

2016-12-26

White light-emitting diodes (WLEDs) with quantum dots (QDs) and phosphor have attracted tremendous attentions due to their excellent color rendering ability. In the packaging process, QDs layer and phosphor-silicone layer tend to be separated to reduce the reabsorption losses, and to maintain the stability of QDs surface ligands. This study investigated the packaging sequence between QDs and phosphor on the optical and thermal performances of WLEDs. The output optical power and PL spectra were measured and analyzed, and the temperature fields were simulated and validated experimentally by infrared thermal imager. It was found that when driven by 60 mA, the QDs-on-phosphor type WLEDs achieved luminous efficiency (LE) of 110 lm/W, with color rendering index (CRI) of Ra = 92 and R9 = 80, while the phosphor-on-QDs type WLEDs demonstrated lower LE of 68 lm/W, with Ra = 57 and R9 = 24. Moreover, the QDs-on-phosphor type WLEDs generated less heat than that of another, consequently the highest temperature in the QDs-on-phosphor type was lower than another, and the temperature difference can reach 12.3°C. Therefore, in terms of packaging sequence, the QDs-on-phosphor type is an optimal packaging architecture for higher optical efficiency, better color rendering ability and lower device temperature.

Investigation of the effect of engine lubricant oil on remote temperature sensing using thermographic phosphors

Energy Technology Data Exchange (ETDEWEB)

Abou Nada, Fahed, E-mail: Fahed.Abou_Nada@forbrf.lth.se; Aldén, Marcus; Richter, Mattias

2016-11-15

Phosphor thermometry, a remote temperature sensing technique, is widely implemented to measure the temperature of different combustion engines components. The presence of engine lubricant can influence the behavior of the applied sensor materials, known as thermographic phosphors, and thus leading to erroneous temperature measurements. The effect of two engine lubricants on decay times originating from six different thermographic phosphors was investigated. The decay time of each thermographic phosphor was investigated as a function of lubricant/phosphor mass ratio. Tests were conducted at temperatures around 293 K and 376 K for both lubricants. The investigations revealed that ZnO:Zn and ZnS:Ag are the only ones that exhibit a change of the decay time as function of the lubricant/phosphor mass ratio. While the remaining thermographic phosphors, namely BaMg{sub 2}Al{sub 16}O{sub 27}:Eu (BAM), Al{sub 2}O{sub 3}-coated BaMg{sub 2}Al{sub 16}O{sub 27}:Eu, La{sub 2}O{sub 2}S:Eu, Mg{sub 3}F{sub 2}GeO{sub 4}:Mn, displayed no sensitivity of their characteristic decay time on to the presence of lubricant on the porous coating. Biases in the calculated temperature are to be expected if the utilized thermographic phosphor displays decay time sensitivity to the existence of the engine lubricant within the sensor. Such distortions are concealed and can occur undetected leading to false temperature readings for the probed engine component.

Rare Earth Free Zn3V2O8 Phosphor with Controlled Microstructure and Its Photocatalytic Activity

Directory of Open Access Journals (Sweden)

Hom Nath Luitel

2013-01-01

Full Text Available Microsphere of rare earth free phosphor, Zn3V2O8, with broadband yellowish white emission was synthesized by combustion route and compared with the hydrothermal, sol-gel, and solid state reaction methods. The phosphor samples were characterized by X-ray diffraction and scanning electron microscopy. UV-visible absorption and photoluminescence (PL emission and excitation spectra were investigated for these phosphors. Zn3V2O8 phosphor containing 10 mol% of H3BO3 flux exhibited enhanced PL emission showing broadband from 450 nm to 750 nm. Effect of stoichiometry of Zn and V on the host lattice and its effect on the PL emission spectra were studied. Series of Mg3V2O8, Ca3V2O8, and Sr3V2O8 phosphors were also synthesized and compared to the Zn3V2O8 phosphor in terms of PL emission and internal quantum yield, and it was found that Zn3V2O8 is the most efficient phosphor among the other phosphors studied with quantum yield of 60%. The visible light irradiated photocatalytic activity of these phosphors was investigated and it was found that the hydrothermal Zn3V2O8 exhibited enhanced activity.

Preparation and Characterization of UV Emitting Fluoride Phosphors for Phototherapy Lamps

Science.gov (United States)

Belsare, P. D.; Moharil, S. V.; Joshi, C. P.; Omanwar, S. K.

2011-10-01

The use of ultraviolet radiation for the treatment of various skin diseases is well known for long time. Phototherapy employs ultraviolet-blue radiation to cure skin diseases. The basis of phototherapy is believed to be the direct interaction of light of certain frequencies with tissue to cause a change in immune response. Currently dermatologists use UV lamps having specific emissions in UV region for treating various skin diseases. The treatment of skin diseases using artificial sources of UV radiation is now well established and more than 50 types of skin diseases are treated by phototherapy. This is an effective treatment for many skin disorders, such as psoriasis, vitiligo, ofujis disease, morphea , scleroderma, cutaneous T-cell lymphoma, lupus erythematosus, hyperbilirubinemia commonly known as infant jaundice, acne vulgaris, This paper reports photoluminescence properties of UV emitting fluoride phosphors prepared by wet chemical method. Emission characteristics of these phosphors are found similar to those of commercial UV lamp phosphors with comparable intensities. The usefulness of UV emitting fluoride phosphor is discussed in the paper.

Rare earth elements recycling from waste phosphor by dual hydrochloric acid dissolution

International Nuclear Information System (INIS)

Liu, Hu; Zhang, Shengen; Pan, Dean; Tian, Jianjun; Yang, Min; Wu, Maolin; Volinsky, Alex A.

2014-01-01

Highlights: • The article provides a new method for recycling rare earth (RE) from waste phosphor. • When compared with the traditional methods, leach rate was much higher. • Y–Eu concentrate and Tb–Ce concentrate were obtained successively. • It would reduce the burden of later extraction, separation and purification. - Abstract: This paper is a comparative study of recycling rare earth elements from waste phosphor, which focuses on the leaching rate and the technical principle. The traditional and dual dissolution by hydrochloric acid (DHA) methods were compared. The method of dual dissolution by hydrochloric acid has been developed. The Red rare earth phosphor (Y 0.95 Eu 0.05 ) 2 O 3 in waste phosphor is dissolved during the first step of acid leaching, while the Green phosphor (Ce 0.67 Tb 0.33 MgAl 11 O 19 ) and the Blue phosphor (Ba 0.9 Eu 0.1 MgAl 10 O 17 ) mixed with caustic soda are obtained by alkali sintering. The excess caustic soda and NaAlO 2 are removed by washing. The insoluble matter is leached by the hydrochloric acid, followed by solvent extraction and precipitation (the DHA method). In comparison, the total leaching rate of the rare earth elements was 94.6% by DHA, which is much higher than 42.08% achieved by the traditional method. The leaching rate of Y, Eu, Ce and Tb reached 94.6%, 99.05%, 71.45%, and 76.22%, respectively. DHA can decrease the consumption of chemicals and energy. The suggested DHA method is feasible for industrial applications

Process engineering challenges of uranium extraction from phosphoric acid on industrial scale

International Nuclear Information System (INIS)

Mouriya, Govind; Singh, Dhirendra; Nath, A.K.; Majumdar, D.

2014-01-01

Heavy Water Board (HWB) is a constituent unit of the Department of Atomic Energy. One of the diversified activities undertaken by HWB is pursuing exploitation of non-conventional resources for recovery of uranium from wet phosphoric acid being the most prominent one. Amongst the feasible processes for recovery of uranium from phosphoric acid is solvent extraction. Use of in-house solvent produced by HWB, is another key driver. To garner necessary information for developing the industrial scale facilities, the process has been studied in the laboratory scale, mini scale, bench scale at Heavy Water Plant, Talcher. The process was subsequently scaled up to an industrial prototype scale unit and was set up as a Technology Demonstration Plant coupled with a commercial phosphoric acid plant. The plant has successfully processed more than 2 lakh m 3 of wet phosphoric acid and all the parameters including the product, Yellow Cake have been qualified. No adverse effect has been observed in the fertilizer produced. The main characteristics of the process and subsequent process innovations are discussed in this paper. These innovations have been carried out to overcome hurdles faced during commissioning and subsequent operations of the Plant. The innovations include improved pretreatment of the wet phosphoric acid for feeding to the extraction cycle, improved control of the first cycle chemical environment, reducing the strength of the phosphoric acid used for stripping, reducing the number of equipment and machineries, alteration in solvent composition used in the first and second cycle in the solvent extraction units of the plant. (author)

Study of phase transformation processes in steel after phosphor ion implantation and following thermal treatment

International Nuclear Information System (INIS)

Zhetbaev, A.K.; Vereshchak, N.F.; Satpaev, K.K.; Dosmagambetov, T.D.; Serikbaeva, Z.T.

1999-01-01

In the paper process of phase transformation after phosphor ion implantation in steel-45 and annealing in vacuum at 1000 deg C and irradiation by various doses of phosphor ions with energy 100 keV an accelerator are researched by conversion electron method. The phosphor overall solubility in iron is equal 4.53 %. Implantation dose below 6·10 17 ions/cm 2 allows increase phosphor ions content in implantation region to 35 %. Therefore, iron phosphides (Fe 3 P, Fe 2 P and Fe P) forming are possible. (author)

Synthesis and complex forming property of phosphor acid derivatives

International Nuclear Information System (INIS)

Babaev, B.N.

2004-01-01

Full text:With the aim to get new effective and selective extra gents of noble and non-ferrous metals from acid solution and industrial sewage, research of the dependence of 'structure effectiveness' the various phosphor acid derivatives with logical changeable structure (thio phosphor acids, derivatives of dialkoxythiophosphor, O-alkyl-methylphosphon, alkylphenylphosphon, diphenylphosphine acids also 4 methyl-1,3,2 dioxaphosphorinane) which contain different functional groups, the remains of heterocyclic amines and alkaloids, new derivatives of some analytical reagents were synthesized. The structure of synthesized compounds is approved by the results of IR-, PMR-, mass-spectrum analyze. Researching mass-spectrum decay of synthesized phosphor acid derivatives we defined that differing from O-dihexyl-S-propargyl-benzylthio phosphat, mass spectrum decay of O-dialkyl-S-(piperdynobutin-2-il)thio phosphat is characterized by the appearing [M-H] + ions and during the decay ions with high intensiveness are formed. Fragmentation of M + O-alkyl-O-(aminoalkyl)phenylphosphonate proceeds in various directions and characterized with the great number of phosphor containing ions, the possession of the second phenyl radical in the molecule of diphenylphosphon acid derivatives changes the fragmentation of molecular ion of diphenylphosphon acid derivatives. The process of extraction of noble (Au, Ag, Pt, Pd, Os) metals from hydrochloric-sulphur-nitrogen acid medium was analyzed by radioactive indicator's method. It was noticed that structure, strength, conformation of compounds, the temperature, of acid medium (0,1-10 M) and the nature of acids (HCL, H 2 SO 4 , HNO 3 ) could have strong influence to the effectiveness of metal extraction. During the research of metals extraction from pure solutions we can see the followings: 1) There are such substances, which can be used as effective group reagent towards the Au, Ag and Pd. 2) Derivatives with acetylene extract ions of gold from

Avoiding, transforming, transitioning: pathways to sustainable low carbon passenger transport in developing countries

DEFF Research Database (Denmark)

Meza, Maria Josefina Figueroa; Fulton, Lewis; Tiwari, Geetam

2013-01-01

This review examines conditions affecting road passenger transport in developing countries that can be instrumental to building a pathway for reducing carbon emissions while concurrently meeting sustainable development goals. By contrasting present and future status of these conditions a vision...... in motorized travel are also necessary from OECD countries; the focus there is given to what level of pricing and regulatory interventions could change behavior. The articulation of detailed visions can help clarify and prioritize areas where policy efforts can have great impact. Strong actions are necessary...

Influence of dome phosphor particle concentration on mid-power LED thermal resistance

NARCIS (Netherlands)

Alexeev, A.; Martin, G.; Hildenbrand, V.D.; Bosschaart, K.J.

2016-01-01

The modern white mid-power LEDs usually contain phosphor particles encapsulated in silicone dome material. The particles convert the blue light emitted from the epitaxial layer and play significant role in thermal processes of LED packages. In this paper the influence of the phosphor particles

Alternative magnesium source for phosphorous recovery – a feasibility and economic analysis

DEFF Research Database (Denmark)

Quist-Jensen, Cejna Anna; Jørgensen, Mads Koustrup; Christensen, Morten Lykkegaard

Conventional reservoirs of phosphorous are in high risk of depletion in near future, thus nontraditional and sustainable recovery-practices are essential to ensure its adequate supply in future. Today phosphorous is being recovered from wastewater at industrial scale by addition of MgCl2. However...

doped LiMgPO4 phosphor

Indian Academy of Sciences (India)

attention because of their remarkable luminescence proper- ties and .... Figure 1. (a) X-ray diffraction patterns of LiMgPO4:Tb3+ phosphor and (b) standard data. ICDD file. .... ground signal which affects the signal to noise ratio [17]. MDD was ...

Study on the relationship between uranium and phosphor in deposit No.60

International Nuclear Information System (INIS)

Zhang Wanliang

1997-01-01

The deposit No.60 is a large uranium-phosphor one located at the eastern margin of the volcanic basin No.65, and controlled by the stratigraphic horizon of the middle-lower part of the third member of the Ehuling Formation composed of volcaniclastic and terrigeneous classic rocks. Uranium and phosphor were preliminarily concentrated together during the formation of ore-hosting layer, and then reactivated, transported and reprecipitated together under the action of tectonothermal process, leading to the concentration of uranium in cellophane in the adsorption state. Uranium and phosphor are closely associated with the correlation coefficient of up to 0.8-0.9

Carbon Dioxide Capture by Deep Eutectic Solvent Impregnated Sea Mango Activated Carbon

Science.gov (United States)

Zulkurnai, N. Z.; Ali, U. F. Md.; Ibrahim, N.; Manan, N. S. Abdul

2018-03-01

The increment amount of the CO2 emission by years has become a major concern worldwide due to the global warming issue. However, the influence modification of activated carbon (AC) has given a huge revolution in CO2 adsorption capture compare to the unmodified AC. In the present study, the Deep Eutectic Solvent (DES) modified surface AC was used for Carbon Dioxide (CO2) capture in the fixed-bed column. The AC underwent pre-carbonization and carbonization processes at 519.8 °C, respectively, with flowing of CO2 gas and then followed by impregnation with 53.75% phosphoric acid (H3PO4) at 1:2 precursor-to-activant ratios. The prepared AC known as sea mango activated carbon (SMAC) was impregnated with DES at 1:2 solid-to-liquid ratio. The DES is composing of choline chloride and urea with ratio 1:2 choline chloride to urea. The optimum adsorption capacity of SMAC was 33.46 mgco2/gsol and 39.40 mgco2/gsol for DES modified AC (DESAC).

Exploration of swapping enzymatic function between two proteins: A simulation study of chorismate mutase and isochorismate pyruvate lyase

Science.gov (United States)

Choutko, Alexandra; Eichenberger, Andreas P; Gunsteren, Wilfred F; Dolenc, Jožica

2013-01-01

The enzyme chorismate mutase EcCM from Escherichia coli catalyzes one of the few pericyclic reactions in biology, the transformation of chorismate to prephenate. The isochorismate pyruvate lyase PchB from Pseudomonas aeroginosa catalyzes another pericyclic reaction, the isochorismate to salicylate transformation. Interestingly, PchB possesses weak chorismate mutase activity as well thus being able to catalyze two distinct pericyclic reactions in a single active site. EcCM and PchB possess very similar folds, despite their low sequence identity. Using molecular dynamics simulations of four combinations of the two enzymes (EcCM and PchB) with the two substrates (chorismate and isochorismate) we show that the electrostatic field due to EcCM at atoms of chorismate favors the chorismate to prephenate transition and that, analogously, the electrostatic field due to PchB at atoms of isochorismate favors the isochorismate to salicylate transition. The largest differences between EcCM and PchB in electrostatic field strengths at atoms of the substrates are found to be due to residue side chains at distances between 0.6 and 0.8 nm from particular substrate atoms. Both enzymes tend to bring their non-native substrate in the same conformation as their native substrate. EcCM and to a lower extent PchB fail in influencing the forces on and conformations of the substrate such as to favor the other chemical reaction (isochorismate pyruvate lyase activity for EcCM and chorismate mutase activity for PchB). These observations might explain the difficulty of engineering isochorismate pyruvate lyase activity in EcCM by solely mutating active site residues. PMID:23595942

Exploration of swapping enzymatic function between two proteins: a simulation study of chorismate mutase and isochorismate pyruvate lyase.

Science.gov (United States)

Choutko, Alexandra; Eichenberger, Andreas P; van Gunsteren, Wilfred F; Dolenc, Jožica

2013-06-01

The enzyme chorismate mutase EcCM from Escherichia coli catalyzes one of the few pericyclic reactions in biology, the transformation of chorismate to prephenate. The isochorismate pyruvate lyase PchB from Pseudomonas aeroginosa catalyzes another pericyclic reaction, the isochorismate to salicylate transformation. Interestingly, PchB possesses weak chorismate mutase activity as well thus being able to catalyze two distinct pericyclic reactions in a single active site. EcCM and PchB possess very similar folds, despite their low sequence identity. Using molecular dynamics simulations of four combinations of the two enzymes (EcCM and PchB) with the two substrates (chorismate and isochorismate) we show that the electrostatic field due to EcCM at atoms of chorismate favors the chorismate to prephenate transition and that, analogously, the electrostatic field due to PchB at atoms of isochorismate favors the isochorismate to salicylate transition. The largest differences between EcCM and PchB in electrostatic field strengths at atoms of the substrates are found to be due to residue side chains at distances between 0.6 and 0.8 nm from particular substrate atoms. Both enzymes tend to bring their non-native substrate in the same conformation as their native substrate. EcCM and to a lower extent PchB fail in influencing the forces on and conformations of the substrate such as to favor the other chemical reaction (isochorismate pyruvate lyase activity for EcCM and chorismate mutase activity for PchB). These observations might explain the difficulty of engineering isochorismate pyruvate lyase activity in EcCM by solely mutating active site residues. © 2013 The Protein Society.

Recovering uranium from phosphoric acid

International Nuclear Information System (INIS)

Abodishish, H.A.; Ritchey, R.W.

1982-01-01

Precipitation of Fe 3 HN 4 H 8 (PO 4 ) 6 is prevented in the second cycle extractor, in a two cycle uranium recovery process, by washing ammonia laden organic solvent stream, from the second cycle stripper, with first cycle raffinate iron stream containing phosphoric acid, prior to passing the solvent stream into the second cycle extractor. (author)

Combustion synthesis of CaSc2O4:Ce3+ nano-phosphors in a closed system

International Nuclear Information System (INIS)

Peng Wenfang; Zou Shaoyu; Liu Guanxi; Xiao Quanlan; Zhang Rui; Xie Lijuan; Cao Liwei; Meng Jianxin; Liu Yingliang

2011-01-01

Highlights: → CaSc 2 O 4 :Ce 3+ nano-phosphors can be prepared by a single-step combustion method. → The ignition temperature is the lowest in the combustion synthesis of Ce 3+ /Eu 2+ doped phosphors. → The as-prepared nano-phosphors give a uniform particle size in the range of 15-20 nm and have highly dispersity and fluorescence intensity. → It is a convenient method for preparation of monodispersed oxide nano-phosphors, especially those being sensitive to air at high temperature. - Abstract: The CaSc 2 O 4 :Ce 3+ nano-phosphors were successfully prepared by a single-step combustion method at an ignition temperature as low as 200 deg. C in a closed autoclave using glycine as a fuel and PEG4000 as a dispersant. The samples were characterized by X-ray diffraction (XRD), photoluminescence (PL) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscope (TEM). The results revealed that CaSc 2 O 4 :Ce 3+ nano-phosphors can be conveniently prepared at an ignition temperature as low as 200 deg. C, which was much lower than that in the ordinary combustion methods. The optimized ignition temperature was 220 deg. C. The CaSc 2 O 4 :Ce 3+ nano-phosphors give a uniform particle size in the range of 15-20 nm. The low ignition temperature and the addition of PEG4000 dispersant play important roles in the formation of small sized nanoparticles. The as-prepared nano-phosphors were incompact aggregates, but highly dispersed nano-phosphors can be obtained after further ultrasonic treatment. The CaSc 2 O 4 :Ce 3+ nano-phosphors give satisfactory luminescence characteristic benefiting from the closed circumstance, in which cerium atoms can be isolated from the oxidizing atmosphere and non-fluorescent Ce 4+ ions can be ruled out. The present highly dispersed CaSc 2 O 4 :Ce 3+ nano-phosphors with efficient fluorescence are promising in the field of biological labeling, and the present low temperature combustion method is facile and convenient and can

Photosynthetic carbon fixation pathways in Zostera marina and three Florida seagrasses

Energy Technology Data Exchange (ETDEWEB)

Beer, S.; Wetzel, R.G.

1982-06-01

The photosynthetic carbon fixation pathways of four seagrass species, Zostera marina L. from Alaska and Thalassia testudinum Banks ex Konig, Syringodium filiforme Kutz. and Halodule wrightii Aschers. from the Gulf of Mexico, were investigated with a /sup 14/C pulse-chase technique. All species were found to be principally of the C/sub 3/ type. However, Thalassia and Halodule had higher initial incorporation rates into organic acids than is typical for terrestrial C/sub 3/ plants. Of 11 seagrass species investigated thus far for C/sub 3/ or C/sub 4/ metabolism using this technique, 10 were found to be principally of the C/sub 3/ type while only one exhibited C/sub 4/ metabolism.