Science.gov

Sample records for carbonic acid retreatment

  1. Carbonic Acid Retreatment of Biomass

    SciTech Connect

    Baylor university

    2003-06-01

    This project sought to address six objectives, outlined below. The objectives were met through the completion of ten tasks. (1) Solidify the theoretical understanding of the binary CO{sub 2}/H{sub 2}O system at reaction temperatures and pressures. The thermodynamics of pH prediction have been improved to include a more rigorous treatment of non-ideal gas phases. However it was found that experimental attempts to confirm theoretical pH predictions were still off by a factor of about 1.8 pH units. Arrhenius experiments were carried out and the activation energy for carbonic acid appears to be substantially similar to sulfuric acid. Titration experiments have not yet confirmed or quantified the buffering or acid suppression effects of carbonic acid on biomass. (2) Modify the carbonic acid pretreatment severity function to include the effect of endogenous acid formation and carbonate buffering, if necessary. It was found that the existing severity functions serve adequately to account for endogenous acid production and carbonate effects. (3) Quantify the production of soluble carbohydrates at different reaction conditions and severity. Results show that carbonic acid has little effect on increasing soluble carbohydrate concentrations for pretreated aspen wood, compared to pretreatment with water alone. This appears to be connected to the release of endogenous acids by the substrate. A less acidic substrate such as corn stover would derive benefit from the use of carbonic acid. (4) Quantify the production of microbial inhibitors at selected reaction conditions and severity. It was found that the release of inhibitors was correlated to reaction severity and that carbonic acid did not appear to increase or decrease inhibition compared to pretreatment with water alone. (5) Assess the reactivity to enzymatic hydrolysis of material pretreated at selected reaction conditions and severity. Enzymatic hydrolysis rates increased with severity, but no advantage was detected for

  2. Re-treatment of relapsed Paget's disease of bone with zoledronic acid: results from an open-label study.

    PubMed

    Reid, Ian R; Brown, Jacques P; Levitt, Naomi; Román Ivorra, José A; Bachiller-Corral, Javier; Ross, Ian L; Su, Guoqin; Antunez-Flores, Oscar; Aftring, R Paul

    2013-01-01

    Six patients from the phase 3 trials of zoledronic acid in Paget's disease, who had received zoledronic acid initially and had subsequently relapsed, were entered into an open re-treatment study. Following re-treatment, each patient reached similar absolute nadirs of serum alkaline phosphatase to those recorded after their first dose. No significant adverse events were reported. It is concluded that, while re-treatment of Paget's disease with zoledronic acid is rarely needed, it is safe and effective, with no evidence of treatment resistance based on this small cohort. PMID:24422139

  3. Retreat, Hell!

    ERIC Educational Resources Information Center

    Sims, Wil

    1978-01-01

    Describes an annual fall retreat for junior college newspaper staffs, which involves a program of workshops and discussions about problems, goals, and staff members' roles; offers advice on planning such a retreat. (GW)

  4. Observed high-altitude warming and snow cover retreat over Tibet and the Himalayas enhanced by black carbon aerosols

    NASA Astrophysics Data System (ADS)

    Xu, Y.; Ramanathan, V.; Washington, W. M.

    2016-02-01

    Himalayan mountain glaciers and the snowpack over the Tibetan Plateau provide the headwater of several major rivers in Asia. In situ observations of snow cover extent since the 1960s suggest that the snowpack in the region have retreated significantly, accompanied by a surface warming of 2-2.5 °C observed over the peak altitudes (5000 m). Using a high-resolution ocean-atmosphere global climate model and an observationally constrained black carbon (BC) aerosol forcing, we attribute the observed altitude dependence of the warming trends as well as the spatial pattern of reductions in snow depths and snow cover extent to various anthropogenic factors. At the Tibetan Plateau altitudes, the increase in atmospheric CO2 concentration exerted a warming of 1.7 °C, BC 1.3 °C where as cooling aerosols cause about 0.7 °C cooling, bringing the net simulated warming consistent with the anomalously large observed warming. We therefore conclude that BC together with CO2 has contributed to the snow retreat trends. In particular, BC increase is the major factor in the strong elevation dependence of the observed surface warming. The atmospheric warming by BC as well as its surface darkening of snow is coupled with the positive snow albedo feedbacks to account for the disproportionately large role of BC in high-elevation regions. These findings reveal that BC impact needs to be properly accounted for in future regional climate projections, in particular on high-altitude cryosphere.

  5. Observed high-altitude warming and snow cover retreat over Tibet and the Himalayas enhanced by black carbon aerosols

    DOE PAGESBeta

    Xu, Y.; Ramanathan, V.; Washington, W. M.

    2016-02-05

    Himalayan mountain glaciers and the snowpack over the Tibetan Plateau provide the headwater of several major rivers in Asia. In situ observations of snow cover extent since the 1960s suggest that the snowpack in the region have retreated significantly, accompanied by a surface warming of 2–2.5°C observed over the peak altitudes (5000 m). Using a high-resolution ocean–atmosphere global climate model and an observationally constrained black carbon (BC) aerosol forcing, we attribute the observed altitude dependence of the warming trends as well as the spatial pattern of reductions in snow depths and snow cover extent to various anthropogenic factors. At themore » Tibetan Plateau altitudes, the increase in atmospheric CO2 concentration exerted a warming of 1.7°C, BC 1.3°C where as cooling aerosols cause about 0.7°C cooling, bringing the net simulated warming consistent with the anomalously large observed warming. We therefore conclude that BC together with CO2 has contributed to the snow retreat trends. In particular, BC increase is the major factor in the strong elevation dependence of the observed surface warming. The atmospheric warming by BC as well as its surface darkening of snow is coupled with the positive snow albedo feedbacks to account for the disproportionately large role of BC in high-elevation regions. Here, these findings reveal that BC impact needs to be properly accounted for in future regional climate projections, in particular on high-altitude cryosphere.« less

  6. Observed high-altitude warming and snow cover retreat over Tibet and the Himalayas enhanced by black carbon aerosols

    NASA Astrophysics Data System (ADS)

    Xu, Y.; Ramanathan, V.; Washington, W. M.

    2015-07-01

    Himalayan mountain glaciers and the snowpack over the Tibetan Plateau provide the headwater of several major rivers in Asia. In-situ observations of snow cover fraction since the 1960s suggest that the snow pack in the region have retreated significantly, accompanied by a surface warming of 2-2.5 °C observed over the peak altitudes (5000 m). Using a high-resolution ocean-atmosphere global climate model and an observationally constrained black carbon (BC) aerosol forcing, we attribute the observed altitude dependence of the warming trends as well as the spatial pattern of reductions in snow depths and snow cover fraction to various anthropogenic factors. At the Tibetan Plateau altitudes, the increase of atmospheric CO2 concentration exerted a warming of 1.7 °C, BC 1.3 °C where as cooling aerosols cause about 0.7 °C cooling, bringing the net simulated warming consistent with the anomalously large observed warming. We therefore conclude that BC together with CO2 has contributed to the snow retreat trends. Especially, BC increase is the major factor in the strong elevation dependence of the observed surface warming. The atmospheric warming by BC as well as its surface darkening of snow are coupled with the positive snow albedo feedbacks to account for the disproportionately large role of BC in high-elevation regions. These findings reveal that BC impact needs to be properly accounted for in future regional climate projections, in particular on high-altitude cryosphere.

  7. Observed high-altitude warming and snow cover retreat over Tibet and the Himalayas enhanced by black carbon aerosols

    DOE PAGESBeta

    Xu, Y.; Ramanathan, V.; Washington, W. M.

    2016-02-05

    Himalayan mountain glaciers and the snowpack over the Tibetan Plateau provide the headwater of several major rivers in Asia. In situ observations of snow cover extent since the 1960s suggest that the snowpack in the region have retreated significantly, accompanied by a surface warming of 2–2.5 °C observed over the peak altitudes (5000 m). Using a high-resolution ocean–atmosphere global climate model and an observationally constrained black carbon (BC) aerosol forcing, we attribute the observed altitude dependence of the warming trends as well as the spatial pattern of reductions in snow depths and snow cover extent to various anthropogenic factors. At the Tibetanmore » Plateau altitudes, the increase in atmospheric CO2 concentration exerted a warming of 1.7 °C, BC 1.3 °C where as cooling aerosols cause about 0.7 °C cooling, bringing the net simulated warming consistent with the anomalously large observed warming. We therefore conclude that BC together with CO2 has contributed to the snow retreat trends. In particular, BC increase is the major factor in the strong elevation dependence of the observed surface warming. The atmospheric warming by BC as well as its surface darkening of snow is coupled with the positive snow albedo feedbacks to account for the disproportionately large role of BC in high-elevation regions. These findings reveal that BC impact needs to be properly accounted for in future regional climate projections, in particular on high-altitude cryosphere.« less

  8. Tunnelling in carbonic acid.

    PubMed

    Wagner, J Philipp; Reisenauer, Hans Peter; Hirvonen, Viivi; Wu, Chia-Hua; Tyberg, Joseph L; Allen, Wesley D; Schreiner, Peter R

    2016-06-14

    The cis,trans-conformer of carbonic acid (H2CO3), generated by near-infrared radiation, undergoes an unreported quantum mechanical tunnelling rotamerization with half-lives in cryogenic matrices of 4-20 h, depending on temperature and host material. First-principles quantum chemistry at high levels of theory gives a tunnelling half-life of about 1 h, quite near those measured for the fastest rotamerizations. PMID:27248671

  9. Measured Black Carbon Deposition on the Sierra Nevada Snow Pack and Implication for Snow Pack Retreat

    SciTech Connect

    Hadley, O.L.; Corrigan, C.E.; Kirchstetter, T.W.; Cliff, S.S.; Ramanathan, V.

    2010-01-12

    Modeling studies show that the darkening of snow and ice by black carbon deposition is a major factor for the rapid disappearance of arctic sea ice, mountain glaciers and snow packs. This study provides one of the first direct measurements for the efficient removal of black carbon from the atmosphere by snow and its subsequent deposition to the snow packs of California. The early melting of the snow packs in the Sierras is one of the contributing factors to the severe water problems in California. BC concentrations in falling snow were measured at two mountain locations and in rain at a coastal site. All three stations reveal large BC concentrations in precipitation, ranging from 1.7 ng/g to 12.9 ng/g. The BC concentrations in the air after the snow fall were negligible suggesting an extremely efficient removal of BC by snow. The data suggest that below cloud scavenging, rather than ice nuclei, was the dominant source of BC in the snow. A five-year comparison of BC, dust, and total fine aerosol mass concentrations at multiple sites reveals that the measurements made at the sampling sites were representative of large scale deposition in the Sierra Nevada. The relative concentration of iron and calcium in the mountain aerosol indicates that one-quarter to one-third of the BC may have been transported from Asia.

  10. Carbonic Acid Pretreatment of Biomass

    SciTech Connect

    G. Peter van Walsum; Kemantha Jayawardhana; Damon Yourchisin; Robert McWilliams; Vanessa Castleberry

    2003-05-31

    This project sought to address six objectives, outlined below. The objectives were met through the completion of ten tasks. 1) Solidify the theoretical understanding of the binary CO2/H2O system at reaction temperatures and pressures. The thermodynamics of pH prediction have been improved to include a more rigorous treatment of non-ideal gas phases. However it was found that experimental attempts to confirm theoretical pH predictions were still off by a factor of about 1.8 pH units. Arrhenius experiments were carried out and the activation energy for carbonic acid appears to be substantially similar to sulfuric acid. Titration experiments have not yet confirmed or quantified the buffering or acid suppression effects of carbonic acid on biomass. 2) Modify the carbonic acid pretreatment severity function to include the effect of endogenous acid formation and carbonate buffering, if necessary. It was found that the existing severity functions serve adequately to account for endogenous acid production and carbonate effects. 3) Quantify the production of soluble carbohydrates at different reaction conditions and severity. Results show that carbonic acid has little effect on increasing soluble carbohydrate concentrations for pretreated aspen wood, compared to pretreatment with water alone. This appears to be connected to the release of endogenous acids by the substrate. A less acidic substrate such as corn stover would derive benefit from the use of carbonic acid. 4) Quantify the production of microbial inhibitors at selected reaction conditions and severity. It was found that the release of inhibitors was correlated to reaction severity and that carbonic acid did not appear to increase or decrease inhibition compared to pretreatment with water alone. 5) Assess the reactivity to enzymatic hydrolysis of material pretreated at selected reaction conditions and severity. Enzymatic hydrolysis rates increased with severity, but no advantage was detected for the use of carbonic

  11. Carbon dioxide sequestration by direct mineral carbonation with carbonic acid

    SciTech Connect

    O'Connor, William K.; Dahlin, David C.; Nilsen, David N.; Walters, Richard P.; Turner, Paul C.

    2000-01-01

    The Albany Research Center (ARC) of the U.S. Dept. of Energy (DOE) has been conducting a series of mineral carbonation tests at its Albany, Oregon, facility over the past 2 years as part of a Mineral Carbonation Study Program within the DOE. Other participants in this Program include the Los Alamos National Laboratory, Arizona State University, Science Applications International Corporation, and the DOE National Energy Technology Laboratory. The ARC tests have focused on ex-situ mineral carbonation in an aqueous system. The process developed at ARC utilizes a slurry of water mixed with a magnesium silicate mineral, olivine [forsterite end member (Mg2SiO4)], or serpentine [Mg3Si2O5(OH)4]. This slurry is reacted with supercritical carbon dioxide (CO2) to produce magnesite (MgCO3). The CO2 is dissolved in water to form carbonic acid (H2CO3), which dissociates to H+ and HCO3 -. The H+ reacts with the mineral, liberating Mg2+ cations which react with the bicarbonate to form the solid carbonate. The process is designed to simulate the natural serpentinization reaction of ultramafic minerals, and for this reason, these results may also be applicable to in-situ geological sequestration regimes. Results of the baseline tests, conducted on ground products of the natural minerals, have been encouraging. Tests conducted at ambient temperature (22 C) and subcritical CO2 pressures (below 73 atm) resulted in very slow conversion to the carbonate. However, when elevated temperatures and pressures are utilized, coupled with continuous stirring of the slurry and gas dispersion within the water column, significant reaction occurs within much shorter reaction times. Extent of reaction, as measured by the stoichiometric conversion of the silicate mineral (olivine) to the carbonate, is roughly 90% within 24 hours, using distilled water, and a reaction temperature of 185?C and a partial pressure of CO2 (PCO2) of 115 atm. Recent tests using a bicarbonate solution, under identical reaction

  12. Carbon dioxide sequestration by direct mineral carbonation with carbonic acid

    SciTech Connect

    O'Connor, W.K.; Dahlin, D.C.; Nilsen, D.N.; Walters, R.P.; Turner, P.C.

    2000-07-01

    The Albany Research Center (ARC) of the US Department of Energy (DOE) has been conducting a series of mineral carbonation tests at its Albany, Oregon, facility over the past 2 years as part of a Mineral Carbonation Study Program within the DOE. The ARC tests have focused on ex-situ mineral carbonation in an aqueous system. The process developed at ARC utilizes a slurry of water mixed with a magnesium silicate mineral, olivine [forsterite and member (mg{sub 2}SiO{sub 4})], or serpentine [Mg{sub 3}Si{sub 2}O{sub 5}(OH){sub 4}]. This slurry is reacted with supercritical carbon dioxide (CO{sub 2}) to produce magnesite (MgCO{sub 3}). The CO{sub 2} is dissolved in water to form carbonic acid (H{sub 2}CO{sub 3}), which dissociates to H{sup +} and HCO{sub 3}{sup {minus}}. The H{sup +} reacts with the mineral, liberating Mg{sup 2+} cations which react with the bicarbonate to form the solid carbonate. The process is designed to simulate the natural serpentinization reaction of ultramafic minerals, and for this reason, these results may also be applicable to in-situ geological sequestration regimes. Results of the baseline tests, conducted on ground products of the natural minerals, have been encouraging. Tests conducted at ambient temperature (22 C) and subcritical CO{sub 2} pressures (below 73 atm) resulted in very slow conversion to the carbonate. However, when elevated temperatures and pressures are utilized, coupled with continuous stirring of the slurry and gas dispersion within the water column, significant reaction occurs within much shorter reaction times. Extent of reaction, as measured by the stoichiometric conversion of the silicate mineral (olivine) to the carbonate, is roughly 90% within 24 hours, using distilled water, and a reaction temperature of 185 C and a partial pressure of CO{sub 2} (P{sub CO{sub 2}}) of 115 atm. Recent tests using a bicarbonate solution, under identical reaction conditions, have achieved roughly 83% conversion of heat treated serpentine

  13. Soil carbon accretion along an age chronosequence formed by the retreat of the Skaftafellsjökull glacier, SE-Iceland

    NASA Astrophysics Data System (ADS)

    Vilmundardóttir, O. K.; Gísladóttir, G.; Lal, R.

    2015-01-01

    Climate warming has led to glacial retreat worldwide, where surfaces exposed to the atmosphere are subjected to weathering, vegetation colonization and new soil formation. On young soils developing along the recessional path left by the Skaftafellsjökull glacier, SE-Iceland, we investigated the accretion of soil organic carbon (SOC) and nitrogen (N), representing an age chronosequence of 120 years. In total, 54 sampling sites were distributed along three moraines deposited in 1890, 1945, and 2003. For comparison, soil samples were collected from nearby birch woodlands (Betula pubescens Ehrh.), representing soils in a mature ecosystem likely to establish on the moraines in the future. Results show that the average SOC and N concentrations increase with time and at faster rates over the latter part of the chronosequence period investigated (1945-1890). After 120 yrs, the soil contains 1.1 kg C m- 2 in the surface layer (0-10 cm), which is still about one third of the 3.2 kg C m- 2 in soil under the birch woodlands. The N stock estimated at 0.06 kg N m- 2 after 120 yrs is almost one fourth of that under the woodlands. The data suggest that landscape affects vegetation establishment and in turn, both landscape and vegetation affect soil development. Thus, concentrations of SOC, N and noncrystalline oxalate extractable Al and Fe are higher within depressions in the proglacial landscape. The comparison of SOC stock in the moraine soils with that under the birch forest shows that the young proglacial soils still have a large potential to accrete SOC within the developing pedosphere. With the observed accrual rate of 9.1 g C m- 2 yr- 1 in the top at 10 cm, it may take the moraine soils an additional period of 220 yrs to accrue SOC stocks comparable with those under the birch forest. Given the fact that all Icelandic glaciers are receding, assessing SOC accretion in new soil formation may be important to off-setting the greenhouse gas emissions.

  14. Role of acid diffusion in matrix acidizing of carbonates

    SciTech Connect

    Hoefner, M.L.; Fogler, H.S.; Stenius, P.; Sjoblom, J.

    1987-02-01

    To increase the efficiency of matrix treatments in carbonates, a new type of retarded acid-in-oil microemulsion system has ben developed. The microemulsion is of low viscosity but can exhibit acid diffusion rates two orders of magnitude lower than aqueous HCl. Decreased acid diffusion delays spending and allows live acid to penetrate the rock matrix more uniformly and to greater distances. Coreflood results show that the microemulsion can stimulate cores in fewer PV's and under conditions of low injection rates where aqueous HCl fails completely. The microemulsion could also conceivably increase acid penetration along any natural fractures and fissures that may be present, thus increasing acidizing efficiency in this type of treatment. The relationship between the acid diffusion rate and the ability of the fluid to matrix-stimulate limestone is investigated.

  15. Synthesis of carbon-13-labeled tetradecanoic acids.

    PubMed

    Sparrow, J T; Patel, K M; Morrisett, J D

    1983-07-01

    The synthesis of tetradecanoic acid enriched with 13C at carbons 1, 3, or 6 is described. The label at the carbonyl carbon was introduced by treating 1-bromotridecane with K13CN (90% enriched) to form the 13C-labeled nitrile, which upon hydrolysis yielded the desired acid. The [3-13C]tetradecanoic acid was synthesized by alkylation of diethyl sodio-malonate with [1-13C]1-bromododecane; the acid was obtained upon saponification and decarboxylation. The label at the 6 position was introduced by coupling the appropriately labeled alkylcadmium chloride with the half acid chloride methyl ester of the appropriate dioic acid, giving the corresponding oxo fatty acid ester. Formation of the tosylhydrazone of the oxo-ester followed by reduction with sodium cyanoborohydride gave the labeled methyl tetradecanoate which, upon hydrolysis, yielded the desired tetradecanoic acid. All tetradecanoic acids were identical to unlabeled analogs as evaluated by gas-liquid chromatography and infrared or NMR spectroscopy. These labeled fatty acids were used subsequently to prepare the correspondingly labeled diacyl phosphatidylcholines. PMID:6631228

  16. Arterial Blood Carbonic Acid Inversely Determines Lactic and Organic Acids

    PubMed Central

    Aiken, Christopher Geoffrey Alexander

    2013-01-01

    Objective: To establish that arterial blood carbonic acid varies inversely with lactic acid in accordance with bicarbonate exchanging for lactate across cell membranes through the anion exchange mechanism to maintain the Gibbs-Donnan equilibrium. Study Design: Over 5 years, lactate was measured on all blood gases taken from neonatal admissions, as well as organic acid whenever electrolytes were required. Results: Arterial blood gases from 63 infants given high calcium TPN were analyzed. Twenty two needed continuous positive airways pressure (CPAP) only and 31 intermittent positive pressure ventilation (IPPV) and surfactant followed by CPAP to treat respiratory distress syndrome in 51 and meconium aspiration syndrome in 2. All survived and were free of infection. Excluded gases were those with high and falling lactate soon after delivery representing perinatal asphyxia, and those on dexamethasone. Strong inverse relations between carbonic and lactic acids were found at all gestational ages and, independent of glomerular filtration, between carbonic and organic acids. Lactate (mmol/L) = 62.53 X PCO2 -0.96(mmHg) r2 0.315, n 1232, p <0.001. Sixty divided by PCO2 is a convenient measure of physiological lactate at any given PCO2. In the first week, 9.13 ± 2.57% of arterial gases from infants on IPPV had lactates above 120/PCO2, significantly more than 4.74 ± 2.73% on CPAP (p<0.05) and 2.47 ± 2.39% on no support. Conclusion: Changes in arterial blood carbonic acid cause immediate inverse changes in lactic acid, because their anions interchange across cell membranes according to the Gibbs –Donnan equilibrium. Increasing PCO2 from 40 to 120 mmHg decreased lactate from 1.5 mmol/L to 0.5 mmol/L, so that the sum of carbonic and lactic acids increased from 2.72 mmol/L to only 4.17 mmol/L. This helps explain the neuroprotective effect of hypercapnoea and highlights the importance of avoiding any degree of hypocapnoea in infants on IPPV. PMID:24392387

  17. Tips for a Successful Leadership Retreat

    ERIC Educational Resources Information Center

    Bonstingl, John Jay

    2005-01-01

    This article focuses on planning a retreat for board, leadership team, or community and business partners. The author provides 10 suggestions for effective retreat planning: (1) Plan one's retreat with a clear purpose in mind; (2) Make retreat more relevant; (3) Build on current and past successes; (4) Make sure the right people are invited and…

  18. USEPA PATHOGEN EQUIVALENCY COMMITTEE RETREAT

    EPA Science Inventory

    The Pathogen Equivalency Committee held its retreat from September 20-21, 2005 at Hueston Woods State Park in College Corner, Ohio. This presentation will update the PEC’s membership on emerging pathogens, analytical methods, disinfection techniques, risk analysis, preparat...

  19. Hypogene Sulfuric Acid Speleogenesis and rare sulfate minerals in Baume Galinière Cave (Alpes-de-Haute-Provence, France). Record of uplift, correlative cover retreat and valley dissection

    NASA Astrophysics Data System (ADS)

    Audra, Philippe; Gázquez, Fernando; Rull, Fernando; Bigot, Jean-Yves; Camus, Hubert

    2015-10-01

    The oxidation of hydrocarbons and sulfide sources (H2S, pyrite) produces sulfuric acid that strongly reacts with bedrock, causing limestone dissolution and complex interactions with other minerals from the bedrock or from cave fillings, mainly clays. This type of cave development, known as Sulfuric Acid Speleogenesis (SAS), is a subcategory of hypogene speleogenesis, where aggressive water rises from depth. It also produces uncommon minerals, mainly sulfates, the typical byproducts of SAS. Baume Galinière is located in Southern France, in the Vaucluse spring watershed. This small maze cave displays characteristic SAS features such as corrosion notches, calcite geodes, iron crusts, and various sulfate minerals. Sulfur isotopes of SAS byproducts (jarosite and gypsum) clearly show they derive from pyrite oxidation. Using XRD and micro-Raman spectroscopy, thirteen minerals were identified, including elemental sulfur, calcite, quartz, pyrite, goethite, gypsum, and fibroferrite, plus all of the six members of the jarosite subgroup (jarosite, argentojarosite, ammoniojarosite, hydroniumjarosite, natrojarosite, plumbojarosite). The Baume Galinière deposits are the first documented cave occurrence of argentojarosite and the second known occurrence of plumbojarosite, hydronium jarosite, ammoniojarosite, and fibroferrite. In the Vaucluse watershed, there were numerous upwellings of deep water along major faults, located at the contact of the karstic aquifer and the overlying impervious covers. The mixing of deep and meteoric waters at shallow depths caused pyrite depositions in numerous caves, including Baume Galinière. Sulfuric Acid Speleogenesis occurred later after base-level drop, when the cave was under shallow phreatic conditions then in the vadose zone, with oxidation of pyrites generating sulfuric acid. Attenuated oxidation is still occurring through condensation of moisture from incoming air. Baume Galinière Cave records the position of the semi-impervious paleo

  20. Isotope composition of carbon in amino acids of solid bitumens

    NASA Astrophysics Data System (ADS)

    Shanina, S. N.; Bushnev, D. A.

    2014-06-01

    Primary data are presented on the isotope composition of carbon in individual amino acids from solid bitumens and several biological objects. The amino acids of biological objects are characterized by wide variations of the isotope composition of carbon. This fact occurs owing to the difference in biochemical paths of metabolism resulting in the synthesis of individual amino acids. The δ13C values are somewhat decreased for individual amino acids in asphaltenes, varying from -7.7 to -31.7‰. The carbon of amino acids is weighted in kerits from Bad'el' compared to asphaltenes. All the natural bitumens retain the characteristic trend for natural substances: the isotopically heavy and light amino acids by carbon are glycine and leucine, respectively. The isotope composition of amino-acid carbon is lightened compared to natural bitumens in the samples formed under a pronounced thermal impact (asphalt-like crust and kirishite).

  1. Is rate of glacial retreat accelerated in Indian Himalaya? (Invited)

    NASA Astrophysics Data System (ADS)

    Kulkarni, A. V.

    2013-12-01

    The Himalaya has one of the largest concentration of glaciers and rivers like Indus, Ganga and Bramhputra originate from this region. The snow and glacier melt is an important source of water for these rivers. However, this source of water may get affected in the near future due to changes in the cryosphere. Therefore, retreat of Himalayan glaciers are discussed extensively in scientific and public forums in India. Conventionally health of glaciers is assessed using changes in glacial length, as it is widely measured. However changes in glacial length and loss in areal extent near terminus needs to be interpreted carefully, as these changes can be influenced by numerous terrain and climatically sensitive parameters. The terrain parameters which can influence glacial retreat are slope, area altitude distribution, debris cover and orientation. In addition, climatically sensitive parameters like mass balance, glacial lakes and black carbon can also influence glacier retreat. These multiple influences can produce a complex pattern of glacial retreat. In this paper long-term glacier retreat in three river basins in the Indian Himalaya as Tista, Baspa and Parbati will be discussed. These basins are located in different climatically sensitive regions and each basin has unique dominant process of mass wasting. In addition to terrain parameters, influence of process like formation and expansion of moraine dammed lakes in Tista basin, deposition of black carbon on accumulation area in Baspa basin and debris cover in Parbati basin will also be discussed. This will provide understanding on varying influence of different mass wasting processes on glacial retreat during last five decades in the Indian Himalaya.

  2. The Perils of Carbonic Acid and Equilibrium Constants.

    ERIC Educational Resources Information Center

    Jencks, William P.; Altura, Rachel A.

    1988-01-01

    Discusses the effects caused by small amounts of carbon dioxide usually present in water and acid-base equilibria of dilute solutions. Notes that dilute solutions of most weak acids and bases undergo significant dissociation or protonation. (MVL)

  3. Columbia Glacier in 1986; 800 meters retreat

    USGS Publications Warehouse

    Krimmel, R.M.

    1987-01-01

    Columbia Glacier, in Prince William Sound, Alaska, continued its rapid retreat in 1986, with a retreat of 800 m. Average velocity of the lower portion of the glacier, 10 September 1986 to 26 January 1987, was three km/yr, or about one-half of the velocity during similar periods for the previous three years. This reduced velocity is a new development in the progression of the retreat, and if the calving rate follows the pattern of previous years, will result in continued retreat. (Author 's abstract)

  4. Carbon-based strong solid acid for cornstarch hydrolysis

    SciTech Connect

    Nata, Iryanti Fatyasari; Irawan, Chairul; Mardina, Primata; Lee, Cheng-Kang

    2015-10-15

    Highly sulfonated carbonaceous spheres with diameter of 100–500 nm can be generated by hydrothermal carbonization of glucose in the presence of hydroxyethylsulfonic acid and acrylic acid at 180 °C for 4 h. The acidity of the prepared carbonaceous sphere C4-SO{sub 3}H can reach 2.10 mmol/g. It was used as a solid acid catalyst for the hydrolysis of cornstarch. Total reducing sugar (TRS) concentration of 19.91 mg/mL could be obtained by hydrolyzing 20 mg/mL cornstarch at 150 °C for 6 h using C4-SO{sub 3}H as solid acid catalyst. The solid acid catalyst demonstrated good stability that only 9% decrease in TRS concentration was observed after five repeat uses. The as-prepared carbon-based solid acid catalyst can be an environmentally benign replacement for homogeneous catalyst. - Highlights: • Carbon solid acid was successfully prepared by one-step hydrothermal carbonization. • The acrylic acid as monomer was effectively reduce the diameter size of particle. • The solid acid catalyst show good catalytic performance of starch hydrolysis. • The solid acid catalyst is not significantly deteriorated after repeated use.

  5. Reduction of Plutonium in Acidic Solutions by Mesoporous Carbons

    SciTech Connect

    Parsons-Moss, Tashi; Jones, Stephen; Wang, Jinxiu; Wu, Zhangxiong; Uribe, Eva; Zhao, Dongyuan; Nitsche, Heino

    2015-12-19

    Batch contact experiments with several porous carbon materials showed that carbon solids spontaneously reduce the oxidation state of plutonium in 1-1.5 M acid solutions, without significant adsorption. The final oxidation state and rate of Pu reduction varies with the solution matrix, and also depends on the surface chemistry and surface area of the carbon. It was demonstrated that acidic Pu(VI) solutions can be reduced to Pu(III) by passing through a column of porous carbon particles, offering an easy alternative to electrolysis with a potentiostat.

  6. Carbon-based strong solid acid for cornstarch hydrolysis

    NASA Astrophysics Data System (ADS)

    Nata, Iryanti Fatyasari; Irawan, Chairul; Mardina, Primata; Lee, Cheng-Kang

    2015-10-01

    Highly sulfonated carbonaceous spheres with diameter of 100-500 nm can be generated by hydrothermal carbonization of glucose in the presence of hydroxyethylsulfonic acid and acrylic acid at 180 °C for 4 h. The acidity of the prepared carbonaceous sphere C4-SO3H can reach 2.10 mmol/g. It was used as a solid acid catalyst for the hydrolysis of cornstarch. Total reducing sugar (TRS) concentration of 19.91 mg/mL could be obtained by hydrolyzing 20 mg/mL cornstarch at 150 °C for 6 h using C4-SO3H as solid acid catalyst. The solid acid catalyst demonstrated good stability that only 9% decrease in TRS concentration was observed after five repeat uses. The as-prepared carbon-based solid acid catalyst can be an environmentally benign replacement for homogeneous catalyst.

  7. Endodontic retreatment. 1: Indications and case selection.

    PubMed

    Chong, B S; Pitt Ford, T R

    1996-10-01

    Conventional root canal treatment, despite having a reportedly high success rate may not invariably lead to the desired healing response in clinical practice because of shortcomings in the treatment. This is the first of two articles on this subject, and will cover indications and case selection for root canal retreatment. Part 2 will discuss methods of retreatment. PMID:9452622

  8. Phosphorylated Mesoporous Carbon as a Solid Acid Catalyst

    SciTech Connect

    Dai, Sheng; Mayes, Richard T; Fulvio, Pasquale F; Ma, Zhen

    2011-01-01

    Mesoporous carbon catalyst supports are attractive due to their wide chemical stability while potentially increasing masstransport through and providing a path for larger molecules to access catalytic sites. Herein we report the synthesis of a 10 phosphorylated mesoporous carbon solid-acid catalyst characterized by NH3-TPD and isopropanol dehydration.

  9. Retreating to Advance Women Geoscience Faculty

    NASA Astrophysics Data System (ADS)

    O'Connell, Suzanne; Holmes, Mary Anne

    2007-11-01

    Geoscience Academics in the Northeast (GAIN) Writing Retreat; Dover, Massachusetts, 29 July to 3 August 2007 Seventeen women geoscientists from New England, New York, and New Jersey assembled for a writing retreat at Boston College's Connors Family Retreat and Conference Center, set on 80 pastoral acres on the outskirts of Boston. Funded through the National Science Foundation ADVANCE program, the retreat had two objectives: to facilitate writing and to develop a supportive community. It succeeded on both accounts. Although new to science, retreats of this sort have long been a highly sought after experience for writers in other disciplines. The potential benefits for scientists, in particular, women scientists, are great. Writing is a cornerstone of our work, yet we struggle to find time for it, juggling the demands of students, teaching, family, domestic chores, and research.

  10. The Strongest Acid: Protonation of Carbon Dioxide.

    PubMed

    Cummings, Steven; Hratchian, Hrant P; Reed, Christopher A

    2016-01-22

    The strongest carborane acid, H(CHB11F11), protonates CO2 while traditional mixed Lewis/Brønsted superacids do not. The product is deduced from IR spectroscopy and calculation to be the proton disolvate, H(CO2)2(+). The carborane acid H(CHB11F11) is therefore the strongest known acid. The failure of traditional mixed superacids to protonate weak bases such as CO2 can be traced to a competition between the proton and the Lewis acid for the added base. The high protic acidity promised by large absolute values of the Hammett acidity function (H0) is not realized in practice because the basicity of an added base is suppressed by Lewis acid/base adduct formation. PMID:26663640

  11. Determination of the acidic sites of purified single-walled carbon nanotubes by acid base titration

    NASA Astrophysics Data System (ADS)

    Hu, H.; Bhowmik, P.; Zhao, B.; Hamon, M. A.; Itkis, M. E.; Haddon, R. C.

    2001-09-01

    We report the measurement of the acidic sites in three different samples of commercially available full-length purified single-walled carbon nanotubes (SWNTs) - as obtained from CarboLex (CLI), Carbon Solutions (CSI) and Tubes@Rice (TAR) - by simple acid-base titration methods. Titration of the purified SWNTs with NaOH and NaHCO 3 solutions was used to determine the total percentage of acidic sites and carboxylic acid groups, respectively. The total percentage of acidic sites in full length purified SWNTs from TAR, CLI and CSI are about 1-3%.

  12. Reaction of folic acid with single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ellison, Mark D.; Chorney, Matthew

    2016-10-01

    The oxygen-containing functional groups on oxidized single-walled carbon nanotubes (SWNTs) are used to covalently bond folic acid molecules to the SWNTs. Infrared spectroscopy confirms intact molecular binding to the SWNTs through the formation of an amide bond between a carboxylic acid group on an SWNT and the primary amine group of folic acid. The folic acid-functionalized SWNTs are readily dispersible in water and phosphate-buffered saline, and the dispersions are stable for a period of two weeks or longer. These folic acid-functionalized SWNTs offer potential for use as biocompatible SWNTs.

  13. The Path of Carbon in Photosynthesis II. Amino Acids

    DOE R&D Accomplishments Database

    Stepka, W.; Benson, A. A.; Calvin, M.

    1948-05-25

    The radioactive amino acid's synthesized from C{sup 14}O{sub 2} by green algae both in the light and in the dark after CO{sub 2}-free preillumination have been separated and identified using paper chromatography and radioautography. The radioactive amino acids identified were aspartic acid, alanine and smaller amounts of 3- and 4-carbon amino acids. This finding as well as the total absence of radioactive glutamic acid substantiates the mechanism for reduction of CO{sub 2} previously postulated by members of this laboratory.

  14. Field evaluation of gelled acid for carbonate formations

    SciTech Connect

    Church, D.C.; Quisenberry, J.L.; Fox, K.B.

    1981-12-01

    A new gelled acid was evaluated in the west Texas, southeast New Mexico, and Oklahoma areas. The purpose of this evaluation was to determine how successful a gelled acid, prepared from xanthan polymer, would be in several carbonate formations. Several types of acidizing techniques were employed. These treatments vary from one to nine stages, with and without diverting agents. More than 20 treatments are summarized. Production figures for the wells treated are discussed, as well as pertinent related information. 5 refs.

  15. Characterization of carbon black modified by maleic acid

    NASA Astrophysics Data System (ADS)

    Asokan, Vijayshankar; Kosinski, Pawel; Skodvin, Tore; Myrseth, Velaug

    2013-09-01

    We present here a method for modifying the surface of carbon black (CB) using a simple heat treatment in the presence of a carboxylic acid as well as water or ethylene glycol as a solvent. CB was mixed with maleic acid and either water or ethylene glycol, and heated at 250°C. Unlike the traditional surface modification processes which use heat treatment of carbon with mineral acids the present modification method using a carboxylic acid proved to be simple and time efficient. CB from two different vendors was used, and the modified samples were characterized by TGA, BET surface area measurement, XRD, particle size and zeta potential measurements, and FTIR. It was found that several material properties, including thermal stability and surface area, of the modified CB are significantly altered relative to the parental carbon samples. This method provides a rapid and simple route to tailor new materials with desired properties.

  16. Glacial Retreat in Chilean Patagonia

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The San Quintin Glacier is the largest outflow glacier of the Northern Patagonian Ice Field in southern Chile. Its terminus is a piedmont lobe just short of the Golfo de Penas on the Pacific Ocean and just north of 47oS. Like many glaciers worldwide during the twentieth century, San Quintin appears to be losing mass and possibly retreating. Such a change is evident in these two photographs taken by astronauts only seven years apart. The first was taken by the crew of STS-068 in October1994 and the second by the Increment 4 crew of the International Space Station in February 2002. Even with the reversal of season and different lighting conditions of these two acquisitions, a loss of mass and change of structure, particularly in the lobe, are strikingly evident in these comparative photos. Glaciers are one of the special topics identified as scientific objectives for monitoring with photography from the International Space Station. Astronaut photography is a complimentary source of remote sensing data available for use with other sensor systems being used to monitor and study glaciers (see an ASTER image of the San Quintin Glacier). They also provide strong, visual context information on glacier environments and processes using a familiar medium, the camera. Images STS068-260-73 and ISS004-E-7267 were provided by the Earth Sciences and Image Analysis Laboratory at Johnson Space Center. Additional images taken by astronauts and cosmonauts can be viewed at the NASA-JSC Gateway to Astronaut Photography of Earth.

  17. Endodontic retreatment: an online study guide.

    PubMed

    2008-05-01

    The Editorial Board of the Journal of Endodontics has developed a literature-based study guide of topical areas related to endodontics. This study guide is intended to give the reader a focused review of the essential endodontic literature and does not cite all possible articles related to each topic. Although citing all articles would be comprehensive, it would defeat the idea of a study guide. This section will cover retreatment rationale, corrosion of silver points, retreatment techniques, removal of posts, and possible complications during retreatment. PMID:18457690

  18. Ocean forcing drives glacier retreat sometimes

    NASA Astrophysics Data System (ADS)

    Bassis, J. N.; Ultee, E.; Ma, Y.

    2015-12-01

    Observations show that marine-terminating glaciers respond to climate forcing nonlinearly, with periods of slow or negligible glacier advance punctuated by abrupt, rapid retreat. Once glacier retreat has initiated, glaciers can quickly stabilize with a new terminus position. Alternatively, retreat can be sustained for decades (or longer), as is the case for Columbia Glacier, Alaska where retreat initiated ~1984 and continues to this day. Surprisingly, patterns of glacier retreat show ambiguous or even contradictory correlations with atmospheric temperature and glacier surface mass balance. Despite these puzzles, observations increasingly show that intrusion of warm subsurface ocean water into fjords can lead to glacier erosion rates that can account for a substantial portion of the total mass lost from glaciers. Here we use a simplified flowline model to show that even relatively modest submarine melt rates (~100 m/a) near the terminus of grounded glaciers can trigger large increases in iceberg calving leading to rapid glacier retreat. However, the strength of the coupling between submarine melt and calving is a strong function of the geometry of the glacier (bed topography, ice thickness and glacier width). This can lead to irreversible retreat when the terminus is thick and grounded deeply beneath sea level or result in little change when the glacier is relatively thin, grounded in shallow water or pinned in a narrow fjord. Because of the strong dependence on glacier geometry, small perturbations in submarine melting can trigger glaciers in their most advanced—and geometrically precarious—state to undergo sudden retreat followed by much slower re-advance. Although many details remain speculative, our model hints that some glaciers are more sensitive than others to ocean forcing and that some of the nonlinearities of glacier response to climate change may be attributable to variations in difficult-to-detect subsurface water temperatures that need to be better

  19. USE OF FATTY ACID STABLE CARBON ISOTOPE RATIO TO INDICATE MICROBIAL CARBON SOURCE IN TROPICAL SOILS

    EPA Science Inventory


    We use measurements of the concentration and stable carbon isotope ratio of individual microbial phospholipid fatty acids (PLFAs) in soils as indicators of live microbial biomass levels, broad microbial community structure, and microbial carbon source. For studies of soil o...

  20. Hydrogen Storage in the Carbon Dioxide - Formic Acid Cycle.

    PubMed

    Fink, Cornel; Montandon-Clerc, Mickael; Laurenczy, Gabor

    2015-01-01

    This year Mankind will release about 39 Gt carbon dioxide into the earth's atmosphere, where it acts as a greenhouse gas. The chemical transformation of carbon dioxide into useful products becomes increasingly important, as the CO(2) concentration in the atmosphere has reached 400 ppm. One approach to contribute to the decrease of this hazardous emission is to recycle CO(2), for example reducing it to formic acid. The hydrogenation of CO(2) can be achieved with a series of catalysts under basic and acidic conditions, in wide variety of solvents. To realize a hydrogen-based charge-discharge device ('hydrogen battery'), one also needs efficient catalysts for the reverse reaction, the dehydrogenation of formic acid. Despite of the fact that the overwhelming majority of these reactions are carried out using precious metals-based catalysts (mainly Ru), we review here developments for catalytic hydrogen evolution from formic acid with iron-based complexes. PMID:26842324

  1. A mechanistic model of wormhole growth in carbonate matrix acidizing and acid fracturing

    SciTech Connect

    Hung, K.M.; Hill, A.D.; Sepehrnoorl, K.

    1989-01-01

    A mathematical model that describes the growth and competition of wormholes during ann acidizing treatment in a carbonate formation was developed. The model is initialized with the distribution of largest pores. Wormhole characteristics (size, length, and distribution) were found too be controlled by acid-injection, diffusion, and fluid-loss rates.

  2. Fluorescent carbon dots capped with PEG200 and mercaptosuccinic acid.

    PubMed

    Gonçalves, Helena; Esteves da Silva, Joaquim C G

    2010-09-01

    The synthesis and functionalization of carbon nanoparticles with PEG(200) and mercaptosuccinic acid, rendering fluorescent carbon dots, is described. Fluorescent carbon dots (maximum excitation and emission at 320 and 430 nm, respectively) with average dimension 267 nm were obtained. The lifetime decay of the functionalized carbon dots is complex and a three component decay time model originated a good fit with the following lifetimes: τ(1) = 2.71 ns; τ(2) = 7.36 ns; τ(3) = 0.38 ns. The fluorescence intensity of the carbon dots is affected by the solvent, pH (apparent pK(a) of 7.4 ± 0.2) and iodide (Stern-Volmer constant of 78 ± 2 M(-1)). PMID:20352303

  3. ELEMENTAL MERCURY ADSORPTION BY ACTIVATED CARBON TREATED WITH SULFURIC ACID

    EPA Science Inventory

    The paper gives results of a study of the adsorption of elemental mercury at 125 C by a sulfuric-acid (H2S04, 50% w/w/ solution)-treated carbon for the removal of mercury from flue gas. The pore structure of the sample was characterized by nitrogen (N2) at -196 C and the t-plot m...

  4. Four Retreats and a Forum: A Meditation on Retreats as a Response to Change.

    ERIC Educational Resources Information Center

    Dobb, Linda S.

    1999-01-01

    Describes four library retreats held by the Bowling Green State University library staff from 1995 to 1998. The retreats reflect changes in library work and management theory that have occurred. The importance of technology to library work is recognized, but there is also a growing realization of the importance of developing a flexible staff…

  5. Do Higher Sea-cliff Retreat Rates Imply Faster Sea-cliff Retreat?

    NASA Astrophysics Data System (ADS)

    Mushkin, A.; Katz, O.; Porat, N.

    2015-12-01

    Inland retreat of sea cliffs in response to post LGM (last glacial maximum) sea-level rise is an ongoing process that affects coastal environments and communities worldwide. Here, we examine a globally recurring pattern where reported sea-cliff retreat rates since the 20th century often appear to exceed longer-term millennial-scale ('background') rates that rarely exceed ~0.1 m/yr. Focusing on Israel's 30-km-long Mediterranean 'Sharon' sea-cliff as a case study we demonstrate that such apparent increase in rates may also reflect a widely acknowledged sampling bias in geologic rate estimates inferred from observation time windows ('Tobs') shorter than process episodicity. We show that this possible bias leads to an ambiguity in conventional rate estimates obtained by averaging observed retreat distances over Tobs, and that as a result despite ubiquitous and robust observations of cliff retreat since the 20th century (e.g., aerial photographs) recent/current retreat rates for many of the world's episodically retreating sea cliffs remain essentially unknown. To address this present limitation in our ability to detect and quantify recent changes in sea-cliff retreat rates we use airborne LiDAR to measure the continuous wave-driven volumetric erosion of collapsed material from the cliff base as an effective upper-bound constraint for the m/yr rate of episodic retreat of the cliff itself. We find that while conventional retreat rate estimates since the 20th century along the Sharon sea cliff artefactually increase up to several m/yr as an inverse function of Tobs, the LiDAR-constrained retreat rates are not susceptible to this sampling bias, are comparable to the cliff's background retreat rate of 0.03-0.07 m/yr since the mid Holocene and thus indicate no recent acceleration in retreat. This ability to unambiguously constrain sea-cliff retreat rates with annual to decadal-scale observations directly impacts the global-scale push to quantify, better understand and

  6. Suicidal chemistry: combined intoxication with carbon monoxide and formic acid.

    PubMed

    Bakovic, Marija; Nestic, Marina; Mayer, Davor

    2016-05-01

    Herein, we present a rare case of suicidal intoxication with carbon monoxide produced via reaction of formic and sulphuric acid with additional toxic effect of formic acid. The deceased was a 22-year-old men found dead in the bathroom locked from the inside. A bucket filled with liquid was found next to him, together with an almost empty canister labeled "formic acid" and another empty unlabeled canister. The postmortem examination revealed corrosive burns of the face, neck and chest, cherry-pink livor mortis, corrosive injury to the oropharyngeal area and trachea, subpleural petechiae, 100 mL of blood in stomach and superficial erosions of stomach mucosa. Toxicology analysis revealed 30% of carboxyhemoglobin in the femoral blood and the presence of the formic acid in various samples. Quantitative analysis of formic acid was performed by measuring methyl ester derivative of formic acid by using headspace gas chromatography with flame ionization detection. The highest concentration of formic acid was measured in the lungs (0.55 g/kg), gastric content (0.39 g/L), and blood (0.28 g/L). In addition, it was established that content of the unlabeled canister had a pH value of 0.79 and contained sulphuric ions. Morphological and toxicology findings suggested that the main route of exposure to formic acid was inhalation of vapors with a possible ingestion of only small amount of liquid acid. The cause of death was determined to be combined intoxication with carbon monoxide and formic acid. PMID:26041513

  7. Summary of the RHIC Retreat 2007

    SciTech Connect

    Pilat,F.; Gardner, C.; Montag, C.; Roser, T.

    2008-08-01

    The RHIC Retreat 2007 took place on July 16-17 2007 at the Foxwoods Resort in CT, about 3 weeks after the end of the RHIC Run-7. The goal of the Retreat is traditionally to plan the upcoming run in the light of the results from the previous one, by providing a snapshot of the present understanding of the machine and a forum for free and frank discussion. A particular attention was paid to the challenge of increasing the time at store, and the related issue of system reliability. An interesting Session covered all new developments aimed to improve the machine performance and luminosity. In Section 2 we summarize the results from Run-7 for RHIC and the injectors and discuss the present objectives of the RHIC program and performance. Sections 3-6 are summaries of the Retreat sessions focused on preparation for deuteron gold and polarized protons, respectively, machine availability and new developments.

  8. CARBON CONTRIBUTION AND CHARACTERISTICS OF HUMIC ACID, FULVIC ACID, PARTICULATE ORGANIC MATTER AND GLOMALIN IN DIVERSE ECOSYSTEMS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Global climate change and soil carbon sequestration issues are entering the forefront of public policy, and emphasis is growing for research on carbon sinks and long-term terrestrial carbon stabilization. Humic acid (HA), fulvic acid (FA), humin and particulate organic matter (POM) have traditionall...

  9. Direct synthesis of formic acid from carbon dioxide by hydrogenation in acidic media

    PubMed Central

    Moret, Séverine; Dyson, Paul J.; Laurenczy, Gábor

    2014-01-01

    The chemical transformation of carbon dioxide into useful products becomes increasingly important as CO2 levels in the atmosphere continue to rise as a consequence of human activities. In this article we describe the direct hydrogenation of CO2 into formic acid using a homogeneous ruthenium catalyst, in aqueous solution and in dimethyl sulphoxide (DMSO), without any additives. In water, at 40 °C, 0.2 M formic acid can be obtained under 200 bar, however, in DMSO the same catalyst affords 1.9 M formic acid. In both solvents the catalysts can be reused multiple times without a decrease in activity. Worldwide demand for formic acid continues to grow, especially in the context of a renewable energy hydrogen carrier, and its production from CO2 without base, via the direct catalytic carbon dioxide hydrogenation, is considerably more sustainable than the existing routes. PMID:24886955

  10. Carbon nanotubes and nucleic acids: tools and targets

    NASA Astrophysics Data System (ADS)

    Onoa, Bibiana; Zheng, Ming; Dresselhaus, Mildred S.; Diner, Bruce A.

    2006-05-01

    Nucleic acids, with their intrinsic structural properties as well as their high specificity, are playing an important role in the rapid development of nano-technologies. In turn, these new technologies and their efficient performance enable fast and precise methods for detection of nucleic acids, improving the diagnosis of diseases and identification of pathogens. We discuss the use of nucleic acids to disperse and sort single walled carbon nanotubes (SWNTs), and carbon nanotube-based field effect transistors (CNT-FETs) to electrically detect specific nucleic acid sequences. Both DNA and RNA are efficient agents for dispersion and separation of SWNTs by diameter and chirality. Fractions enriched in a narrow band gap distribution of DNA:SWNT hybrids do not alter the electronic performance of field effect transistors. A CNT-FET fulfills the requirements for a nanosensing device that can greatly exceed the existing technologies. Electrical detection of specific nucleic acid sequence could potentially overcome the current limitations of optical detection, by increasing sensitivity and speed, while reducing sample manipulation, size, and cost.

  11. Amino acids of the Murchison meteorite. III - Seven carbon acyclic primary alpha-amino alkanoic acids

    NASA Technical Reports Server (NTRS)

    Cronin, John R.; Pizzarello, Sandra

    1986-01-01

    All of the eighteen possible seven-carbon acyclic primary alpha-amino alkanoic acids have been positively identified in a hot-water extract of the Murchison meteorite by the combined use of gas chromatography-mass spectrometry, ion exchange chromatography and reversed-phase chromatography. None of these amino acids has previously been found in meteorites or in any other natural material. They range in concentration from less than or equal to 0.5 to 5.3 nmol/g. Configuration assignments were made for 2-amino-3,4-dimethylpentanoic acid and allo-2-amino-3,4-dimethylpentanoic acid and the diasteromer ratio was determined. Fifty-five amino acids have now been positively identified in the Murchison meteorite, 36 of which are unknown in terrestrial materials. This unique suite of amino acids is characterized by the occurrence of all structural isomers within the two major classes of amino acids represented, by the predominance of branched chain isomers, and by an exponential decline in amount with increasing carbon chain length within homologous series. These characteristics of the Murchison amino acids are suggestive of synthesis before incorporation into a parent body.

  12. Roof Shield for Advance and Retreat Mining

    NASA Technical Reports Server (NTRS)

    Lewis, E. V.

    1985-01-01

    Shield sections change their configuration to suit mining mode. Articulation cylinders raise rear shield to advance position, and locking cylinders hold it there. To change to retreat position articulation cylinders lower shield. Locking pins at edge of outermost shield plate latch shield to chock base. Shield accommodates roof heights ranging from 36 to 60 inches (0.9 to 1.52 meters).

  13. Karstification without carbonic acid: bedrock dissolution by gypsum- driven dedolomitization

    USGS Publications Warehouse

    Bischoff, J.L.; Julia, R.; Shanks, Wayne C.; Rosenbauer, R.J.

    1994-01-01

    The primary karst-forming process at Lake Banyoles is dedolomitization of basement rocks driven by gypsum dissolution. Karstification takes place along the subsurface contact between the gypsiferous Beuda Formation and the dolomitic Perafita Formation. This process is here recognized for the first time to cause karstification on a large scale; this is significant because it proceeds without the addition of soil-generated carbonic acid. -from Authors

  14. Acid neutralisation capacity of accelerated carbonated stainless steel slag.

    PubMed

    Johnson, D C; MacLeod, C L; Hills, C D

    2003-05-01

    The acid neutralisation capacity test is widely used to assess the long-term performance of waste materials prior to disposal. Samples of fixed mass are exposed to increasing additions of nitric add in sealed containers and the resultant pH is plotted as a titration curve. In this work, the add neutralisation capacity test was used in the assessment of an accelerated carbonated stainless steel slag. Difficulties arose in applying the test procedure to this material. This was largely because of the raised pressure from significant volumes of released carbon dioxide trapped in the sealed sample containers, causing an alteration to leachate pH values. Consequently, the add neutralisation capacity test was modified to enable testing of samples in equilibrium with the atmosphere. No adverse effects on the results from testing of a carbonate free material were recorded. PMID:12803247

  15. Adsorption of naphthenic acids on high surface area activated carbons.

    PubMed

    Iranmanesh, Sobhan; Harding, Thomas; Abedi, Jalal; Seyedeyn-Azad, Fakhry; Layzell, David B

    2014-01-01

    In oil sands mining extraction, water is an essential component; however, the processed water becomes contaminated through contact with the bitumen at high temperature, and a portion of it cannot be recycled and ends up in tailing ponds. The removal of naphthenic acids (NAs) from tailing pond water is crucial, as they are corrosive and toxic and provide a substrate for microbial activity that can give rise to methane, which is a potent greenhouse gas. In this study, the conversion of sawdust into an activated carbon (AC) that could be used to remove NAs from tailings water was studied. After producing biochar from sawdust by a slow-pyrolysis process, the biochar was physically activated using carbon dioxide (CO2) over a range of temperatures or prior to producing biochar, and the sawdust was chemically activated using phosphoric acid (H3PO4). The physically activated carbon had a lower surface area per gram than the chemically activated carbon. The physically produced ACs had a lower surface area per gram than chemically produced AC. In the adsorption tests with NAs, up to 35 mg of NAs was removed from the water per gram of AC. The chemically treated ACs showed better uptake, which can be attributed to its higher surface area and increased mesopore size when compared with the physically treated AC. Both the chemically produced and physically produced AC provided better uptake than the commercially AC. PMID:24766592

  16. Biosynthesis of 2-hydroxyisobutyric acid (2-HIBA) from renewable carbon

    PubMed Central

    2010-01-01

    Nowadays a growing demand for green chemicals and cleantech solutions is motivating the industry to strive for biobased building blocks. We have identified the tertiary carbon atom-containing 2-hydroxyisobutyric acid (2-HIBA) as an interesting building block for polymer synthesis. Starting from this carboxylic acid, practically all compounds possessing the isobutane structure are accessible by simple chemical conversions, e. g. the commodity methacrylic acid as well as isobutylene glycol and oxide. During recent years, biotechnological routes to 2-HIBA acid have been proposed and significant progress in elucidating the underlying biochemistry has been made. Besides biohydrolysis and biooxidation, now a bioisomerization reaction can be employed, converting the common metabolite 3-hydroxybutyric acid to 2-HIBA by a novel cobalamin-dependent CoA-carbonyl mutase. The latter reaction has recently been discovered in the course of elucidating the degradation pathway of the groundwater pollutant methyl tert-butyl ether (MTBE) in the new bacterial species Aquincola tertiaricarbonis. This discovery opens the ground for developing a completely biotechnological process for producing 2-HIBA. The mutase enzyme has to be active in a suitable biological system producing 3-hydroxybutyryl-CoA, which is the precursor of the well-known bacterial bioplastic polyhydroxybutyrate (PHB). This connection to the PHB metabolism is a great advantage as its underlying biochemistry and physiology is well understood and can easily be adopted towards producing 2-HIBA. This review highlights the potential of these discoveries for a large-scale 2-HIBA biosynthesis from renewable carbon, replacing conventional chemistry as synthesis route and petrochemicals as carbon source. PMID:20184738

  17. REACTIONS OF CHLORITE WITH ACTIVATED CARBON AND WITH VANILLIC ACID AND INDAN ADSORBED ON ACTIVATED CARBON

    EPA Science Inventory

    The reaction between chlorite (CO2(-1)) and vanillic acid, at pH 6.0 in the presence of granular activated carbon (GAC), yielded several reaction products identifiable by GC/MS; no products were found in the absence of GAC. Indan and ClO2 or ClO2(-1) reacted in aqueous solution a...

  18. Acetylene-mediated alkylation of monoalkyl carbonates and carbamic acids with tert-amines

    SciTech Connect

    Sasaki, Yoshiyuki

    1996-12-31

    Carbonic acid diesters and carbamic acid esters are useful organic substances as intermediates for the syntheses of several chemicals. They are currently synthesized in industry using the processes based on phosgene or carbon monoxide. On the other hand, since carbon dioxide is an abundant and cheap carbonyl carbon source, and is much less toxic than those raw materials, substantial efforts have been focused on its fixation into carbonyl compounds including carbonic acid diesters and carbamic acid esters. However, their syntheses based on carbon dioxide reported so far require rather expensive substrates like alkyl halides, and are not competitive with the currently adopted industrial processes.

  19. Suicidal carbon monoxide poisoning by combining formic acid and sulfuric acid within a confined space.

    PubMed

    Lin, Peter T; Dunn, William A

    2014-01-01

    Suicide by inhalation of carbon monoxide produced by mixing formic acid and sulfuric acid within a confined space is a rare method of suicide. This method is similar to the so-called "detergent suicide" method where an acid-based detergent is mixed with a sulfur source to produce hydrogen sulfide. Both methods produce a toxic gas that poses significant hazards for death investigators, first responders and bystanders. Carbon monoxide is an odorless gas, while hydrogen sulfide has a characteristic rotten eggs odor, so the risks associated with carbon monoxide are potentially greater due to lack of an important warning signal. While detergent suicides have become increasingly common in the USA, suicide with formic acid and sulfuric acid is rare with only three prior cases being reported. Greater awareness of this method among death investigators is warranted because of the special risks of accidental intoxication by toxic gas and the possibility that this method of suicide will become more common in the future. PMID:24328850

  20. Black Carbon in Sedimentary Organic Carbon in the Northeast Pacific using the Benzene Polycarboxylic Acid Method

    NASA Astrophysics Data System (ADS)

    Coppola, A. I.; Ziolkowski, L. A.; Druffel, E. R.

    2010-12-01

    Black carbon (BC) in the Northeast Pacific ultrafiltered dissolved organic matter (UDOM) was found to be surprisingly old with a 14C age of 18,000 +/-3,000 14C years (Ziolkowski and Druffel, 2010) using the Benzene Polycarboxylic Acid (BPCA) method, while BC in sedimentary organic carbon (SOC) was found to be 2,400-12,900 14C years older than non-BC SOC (Masiello and Druffel, 1998) with a different method. Using the dichromate-sulfuric acid oxidation method (Wolbach and Anders, 1989), Masiello and Druffel (1998) estimated that 12-31% of SOC in the Northeast Pacific and the Southern Ocean surface sediments was black carbon (BC). However, the dichromate-sulfuric acid oxidation may over-estimate the concentration of BC, because this method is more biased toward modern (char) material (Currie et al., 2002). Alternatively, the BPCA method isolates aromatic components of BC as benzene rings substituted with carboxylic acid groups, and provides structural information about the BC. Recent modifications to the BPCA method by Ziolkowski and Druffel (2009) involve few biases in quantifying BC in the continuum between char and soot in UDOM. Here we use the BPCA method to determine the concentrations and 14C values of BC in sediments from three sites in the Northeast Pacific Ocean. Constraining the difference between non-BC SOC and BC-SOC using the BPCA method allows for a more precise estimate of how much BC is present in the sediments and its 14C age. Presumably, the intermediate reservoir of BC is oceanic dissolved organic carbon (DOC) and is, in part, responsible for DOC’s great 14C age. These results can be utilized to better constrain the oceanic carbon budget as a possible sink of BC. References: Currie, L. A., Benner Jr., B. A., Kessler, J.D., et al (2002), A critical evaluation of interlaboratory data on total, elemental, and isotopic carbon in the carbonaceous particle reference material, nist srm 1649a, J. Res. Natl. Inst. Stand. Technol., 107, 279-298. Masiello, C

  1. Amino acids of the Murchison meteorite. II - Five carbon acyclic primary beta-, gamma-, and delta-amino alkanoic acids

    NASA Technical Reports Server (NTRS)

    Cronin, J. R.; Pizzarello, S.; Yuen, G. U.

    1985-01-01

    The five-carbon acyclic primary beta, gamma, and delta amino alkanoic acids of the Murchison meteorite are studied using gas chromatography-mass spectrometry and ion exchange chromatography. The chromatograms reveal that alpha is the most abundant monoamino alkanoic acid followed by gamma and beta, and an exponential increase in the amount of amino acid is observed as the carbon number increases in the homologous series. The influence of frictional heating, spontaneous thermal decomposition, and radiation of the synthesis of amino acids is examined. The data obtained support an amino acid synthesis process involving random combination of single-carbon precursors.

  2. The Board Retreat: For Listening, Learning and Understanding.

    ERIC Educational Resources Information Center

    Read, James W.

    Retreats, which have been used by churches and corporations for some time, are currently being looked into by college presidents and boards of trustees as a means of training and problem solving. While many types of retreats may not be appropriate for boards, a well-planned working retreat can be an effective way for trustees to: (1) really get to…

  3. Carbon dioxide generated from carbonates and acids for sampling blood-feeding arthropods.

    PubMed

    Burkett-Cadena, Nathan D; Blosser, Erik M; Young, Ryan M; Toé, Laurent D; Unnasch, Thomas R

    2015-09-01

    Carbon dioxide (CO2) is utilized to attract mosquitoes and other blood-feeding arthropods to traps around the world. Commercial forms of CO2 (e.g., dry ice and compressed gas) are often unavailable or extremely expensive in developing nations, where vector surveillance is essential to make life-saving decisions. We developed and tested inexpensive and reproducible methods of CO2 production from the combination of acids and carbonates, ranging from very basic (crushed seashells and vinegar) to relatively elaborate (a device that controls the timing of the acid-carbonate reaction and extends the reaction over several hours). When utilized with mosquito traps in Florida, USA and black fly traps in Region des Cascades, Burkina Faso, these carbonate-acid CO2 sources attracted significantly greater numbers of both vector groups, than did unbaited traps. CO2 was generated for more than four hours at levels sufficient to attract vectors over the entire period. The utility of this simple methodology in developing nations should be further evaluated. PMID:26103427

  4. Retreatments after multifocal intraocular lens implantation: an analysis

    PubMed Central

    Gundersen, Kjell Gunnar; Makari, Sarah; Ostenstad, Steffen; Potvin, Rick

    2016-01-01

    Purpose To determine the incidence and etiology of required retreatment after multifocal intraocular lens (IOL) implantation and to evaluate the methods and clinical outcomes of retreatment. Patients and methods A retrospective chart review of 416 eyes of 209 patients from one site that underwent uncomplicated cataract surgery with multifocal IOL implantation. Biometry, the IOL, and refractive data were recorded after the original implantation, with the same data recorded after retreatment. Comments related to vision were obtained both before and after retreatment for retreated patients. Results The multifocal retreatment rate was 10.8% (45/416 eyes). The eyes that required retreatment had significantly higher residual refractive astigmatism compared with those who did not require retreatment (1.21±0.51 D vs 0.51±0.39 D, P<0.01). The retreatment rate for the two most commonly implanted primary IOLs, blended bifocal (10.5%, 16/152) and bilateral trifocal (6.9%, 14/202) IOLs, was not statistically significantly different (P=0.12). In those requiring retreatment, refractive-related complaints were most common. Retreatment with refractive corneal surgery, in 11% of the eyes, and piggyback IOLs, in 89% of the eyes, was similarly successful, improving patient complaints 78% of the time. Conclusion Complaints related to ametropia were the main reasons for retreatment. Residual astigmatism appears to be an important determinant of retreatment rate after multifocal IOL implantation. Retreatment can improve symptoms for a high percentage of patients; a piggyback IOL is a viable retreatment option. PMID:27041983

  5. Carbon fluxes in an acid rain impacted boreal headwater catchment

    NASA Astrophysics Data System (ADS)

    Marx, Anne; Hintze, Simone; Jankovec, Jakub; Sanda, Martin; Dusek, Jaromir; Vogel, Tomas; van Geldern, Robert; Barth, Johannes A. C.

    2016-04-01

    Terrestrial carbon export via inland aquatic systems is a key process in the budget of the global carbon cycle. This includes loss of carbon to the atmosphere via gas evasion from rivers or reservoirs as well as carbon fixation in freshwater sediments. Headwater streams are the first endmembers of the transition of carbon between soils, groundwater and surface waters and the atmosphere. In order to quantify these processes the experimental catchment Uhlirska (1.78 km2) located in the northern Czech Republic was studied. Dissolved inorganic, dissolved organic and particulate organic carbon (DIC, DOC, POC) concentrations and isotopes were analyzed in ground-, soil -and stream waters between 2014 and 2015. In addition, carbon dioxide degassing was quantified via a stable isotope modelling approach. Results show a discharge-weighted total carbon export of 31.99 g C m‑2 yr‑1 of which CO2 degassing accounts 79 %. Carbon isotope ratios (δ13C) of DIC, DOC, and POC (in ‰ VPDB) ranged from -26.6 to -12.4 ‰ from -29.4 to -22.7 ‰ and from -30.6 to -26.6 ‰ respectively. The mean values for DIC are -21.8 ±3.8 ‰ -23.6 ±0.9 ‰ and -19.5 ±3.0 ‰ for soil, shallow ground and surface water compartments. For DOC, these compartments have mean values of -27.1 ±0.3 ‰ -27.0 ±0.8 ‰ and -27.4 ±0.7 ‰Ṁean POC value of shallow groundwaters and surface waters are -28.8 ±0.8 ‰ and -29.3 ±0.5 ‰ respectively. These isotope ranges indicate little turnover of organic material and predominant silicate weathering. The degassing of CO2 caused an enrichment of the δ13C-DIC values of up to 6.8 ‰ between a catchment gauge and the catchment outlet over a distance of 866 m. In addition, the Uhlirska catchment has only negligible natural sources of sulphate, yet SO42‑ accounts for 21 % of major stream water ions. This is most likely a remainder from acid rain impacts in the area.

  6. Effects of acid treatment duration and sulfuric acid molarity on purification of multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Mortazavi, Seyedeh; Novinrooz, Abdul; Reyhani, Ali; Mirershadi, Soghra

    2010-12-01

    Multi-walled carbon nanotubes were synthesized using a Fe-Ni bimetallic catalyst supported by MgO using thermal chemical vapor deposition. Purification processes to remove unwanted carbon structures and other metallic impurities were carried out by boiling in sulfuric acid solution. Various analytical techniques such as TGA/DSC, Raman spectroscopy, SEM, HRTEM and EDAX were employed to investigate the morphology, graphitization and quality of the carbon nanotubes. The obtained results reveal the molarity of sulfuric acid and immersed time of the carbon nanotubes in the acid solution is very effective at purifying multi-walled carbon nanotubes. It was also found that 5 M concentration of boiling sulfuric acid for a 3 h treatment duration led to the highest removal of the impurities with the least destructive effect. Moreover, it was observed that acid treatment results in decreasing of CNTs' diameter.

  7. Effects of acid treatment duration and sulfuric acid molarity on purification of multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Mortazavi, Seyedeh Z.; Novinrooz, Abdul J.; Reyhani, Ali; Mirershadi, Soghra

    2010-12-01

    Multi-walled carbon nanotubes were synthesized using a Fe-Ni bimetallic catalyst supported by MgO using thermal chemical vapor deposition. Purification processes to remove unwanted carbon structures and other metallic impurities were carried out by boiling in sulfuric acid solution. Various analytical techniques such as TGA/DSC, Raman spectroscopy, SEM, HRTEM and EDAX were employed to investigate the morphology, graphitization and quality of the carbon nanotubes. The obtained results reveal the molarity of sulfuric acid and immersed time of the carbon nanotubes in the acid solution is very effective at purifying multi-walled carbon nanotubes. It was also found that 5 M concentration of boiling sulfuric acid for a 3 h treatment duration led to the highest removal of the impurities with the least destructive effect. Moreover, it was observed that acid treatment results in decreasing of CNTs’ diameter.

  8. Electrochemical formation of hydroxide for enhancing carbon dioxide and acid gas uptake by a solution

    DOEpatents

    Rau, Gregory Hudson

    2012-05-15

    A system is described for forming metal hydroxide from a metal carbonate utilizing a water electrolysis cell having an acid-producing anode and a hydroxyl-producing cathode immersed in a water solution of sufficient ionic content to allow an electric current to pass between the hydroxyl-producing cathode and the acid-producing anode. A metal carbonate, in particular water-insoluble calcium carbonate or magnesium carbonate, is placed in close proximity to the acid-producing anode. A direct current electrical voltage is provided across the acid-producing anode and the hydroxyl-producing cathode sufficient to generate acid at the acid-producing anode and hydroxyl ions at the hydroxyl-producing cathode. The acid dissolves at least part of the metal carbonate into metal and carbonate ions allowing the metal ions to travel toward the hydroxyl-producing cathode and to combine with the hydroxyl ions to form the metal hydroxide. The carbonate ions travel toward the acid-producing anode and form carbonic acid and/or water and carbon dioxide. Among other uses, the metal hydroxide formed can be employed to absorb acid gases such as carbon dioxide from a gas mixture. The invention can also generate hydrogen and oxidative gases such as oxygen or chlorine.

  9. Tuning the Carbon Dioxide Absorption in Amino Acid Ionic Liquids.

    PubMed

    Firaha, Dzmitry S; Kirchner, Barbara

    2016-07-01

    One of the possible solutions to prevent global climate change is the reduction of CO2 emissions, which is highly desired for the sustainable development of our society. In this work, the chemical absorption of carbon dioxide in amino acid ionic liquids was studied through first-principles methods. The use of readily accessible and biodegradable amino acids as building blocks for ionic liquids makes them highly promising replacements for the widely applied hazardous aqueous solutions of amines. A detailed insight into the reaction mechanism of the CO2 absorption was obtained through state-of-the-art theoretical methods. This allowed us to determine the reason for the specific CO2 capacities found experimentally. Moreover, we have also conducted a theoretical design of ionic liquids to provide valuable insights into the precise tuning of the energetic and kinetic parameters of the CO2 absorption. PMID:27214652

  10. Reductive dechlorination of carbon tetrachloride using buffered alkaline ascorbic acid.

    PubMed

    Lin, Ya-Ting; Liang, Chenju

    2015-10-01

    Alkaline ascorbic acid (AA) was recently discovered as a novel in-situ chemical reduction (ISCR) reagent for remediating chlorinated solvents in the subsurface. For this ISCR process, the maintenance of an alkaline pH is essential. This study investigated the possibility of the reduction of carbon tetrachloride (CT) using alkaline AA solution buffered by phosphate and by NaOH. The results indicated that CT was reduced by AA, and chloroform (CF) was a major byproduct at a phosphate buffered pH of 12. However, CT was completely reduced by AA in 2M NaOH without CF formation. In the presence of iron/soil minerals, iron could be reduced by AA and Fe(2+) tends to precipitate on the mineral surface to accelerate CT degradation. A simultaneous transfer of hydrogenolysis and dichloroelimination would occur under phosphate buffered pH 12. This implies that a high alkaline environment is a crucial factor for maintaining the dominant pathway of two electron transfer from dianionic AA to dehydroascorbic acid, and to undergo dichloroelimination of CT. Moreover, threonic acid and oxalic acid were identified to be the major AA decomposition products in alkaline solutions. PMID:25912910

  11. Respiratory CO(2) as Carbon Source for Nocturnal Acid Synthesis at High Temperatures in Three Species Exhibiting Crassulacean Acid Metabolism.

    PubMed

    Winter, K; Schröppel-Meier, G; Caldwell, M M

    1986-06-01

    TEMPERATURE EFFECTS ON NOCTURNAL CARBON GAIN AND NOCTURNAL ACID ACCUMULATION WERE STUDIED IN THREE SPECIES OF PLANTS EXHIBITING CRASSULACEAN ACID METABOLISM: Mamillaria woodsii, Opuntia vulgaris, and Kalanchoë daigremontiana. Under conditions of high soil moisture, nocturnal CO(2) gain and acid accumulation had temperature optima at 15 to 20 degrees C. Between 5 and 15 degrees C, uptake of atmospheric CO(2) largely accounted for acid accumulation. At higher tissue temperatures, acid accumulation exceeded net carbon gain indicating that acid synthesis was partly due to recycling of respiratory CO(2). When plants were kept in CO(2)-free air, acid accumulation based on respiratory CO(2) was highest at 25 to 35 degrees C. Net acid synthesis occurred up to 45 degrees C, although the nocturnal carbon balance became largely negative above 25 to 35 degrees C. Under conditions of water stress, net CO(2) exchange and nocturnal acid accumulation were reduced. Acid accumulation was proportionally more decreased at low than at high temperatures. Acid accumulation was either similar over the whole temperature range (5-45 degrees C) or showed an optimum at high temperatures, although net carbon balance became very negative with increasing tissue temperatures. Conservation of carbon by recycling respiratory CO(2) was temperature dependent. At 30 degrees C, about 80% of the dark respiratory CO(2) was conserved by dark CO(2) fixation, in both well irrigated and water stressed plants. PMID:16664827

  12. Activated carbon passes tests for acid-gas cleanup

    SciTech Connect

    Harruff, L.G.; Bushkuhl, S.J.

    1996-06-24

    Use of activated carbon to remove hydrocarbon contaminants from the acid-gas feed to Claus sulfur-recovery units has been successfully pilot tested in Saudi Arabia. Pilot plant results are discussed here along with issues involved in scale-up to commercial size. Heavy hydrocarbons, particularly benzene, toluene, and xylene (BTX) have been linked to coke formation and catalyst deactivation in Claus converters. This deactivation results in reduced sulfur recovery and increased sulfur emissions from these plants. This clean-up process was proven to be capable of removing 95% of the BTX and other C{sub 6}+s from acid gas over a wide range of actual plant conditions. Following the adsorption step, the activated carbon was easily regenerated by use of low-pressure steam. A post-regeneration drying step using plant fuel gas also proved beneficial. The paper discusses feed contaminants, vapor-phase cleanup, testing design, test parameters and results, bed drying after regeneration, regeneration conditions, basic flow, system control, and full-scale installation.

  13. Easy modification of glassy carbon electrode for simultaneous determination of ascorbic acid, dopamine and uric acid.

    PubMed

    Thiagarajan, Soundappan; Tsai, Tsung-Hsuan; Chen, Shen-Ming

    2009-04-15

    A glassy carbon electrode (GCE) has been modified by electrochemical oxidation in mild acidic media (0.1 mol l(-1) H(2)SO(4)) and could be applied for individual and simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA). Oxidized GCE shows a single redox couple (E(0)'=-2.5 mV) which is based on the formation functional groups during the electrochemical pretreatment process. Proposed GCE successfully decreases the over potentials for the oxidation process of these species (AA, DA and UA) comparing with bare GCE. The oxidized GCE has its own simplicity, stability, high sensitivity and possesses the potential for simultaneous determination of AA, DA and UA. PMID:19162467

  14. Amino acids of the Murchison meteorite. I - Six carbon acyclic primary alpha-amino alkanoic acids

    NASA Technical Reports Server (NTRS)

    Cronin, J. R.; Gandy, W. E.; Pizzarello, S.

    1981-01-01

    Six of the seven chain isomers of six-carbon acyclic primary alpha-amino alkanoic acids (leucine isomers) have been either identified or confirmed in hot-water extracts of the Murchison meteorite using combined gas chromatography-mass spectrometry (GC-MS) and ion exchange chromatography. 2-Amino-2-ethylbutyric acid, 2-amino-2,3-dimethylbutyric acid, pseudoleucine, and 2-methylnorvaline were positively identified by GC-MS. These amino acids have not been previously reported to occur in natural materials and may be uniquely meteoritic in origin. The presence of leucine and isoleucine (including the diastereoisomer, alloisoleucine) was confirmed. Peaks corresponding to norleucine were seen by ion-exchange and gas chromatography but characteristic mass spectra were not obtained. The alpha-branched chain isomers in this series are quantitatively the most significant. These results are compared with literature data on amino acid synthesis by electrical discharge and Fischer-Tropsch-type catalysis. Neither model system produces an amino acid suite that is completely comparable to that found in the Murchison meteorite.

  15. Cleaning and retreatment protocol for a debonded ceramic restoration

    PubMed Central

    Alonso-Pérez-Barquero, Jorge; Bruguera-Álvarez, August; Agustín-Panadero, Rubén; Fons-Font, Antonio

    2015-01-01

    Objectives: The aim of this article is to propose a resin cement cleaning protocol for use before recementing a debonded restoration. Study Design: Ceramic samples were fabricated from IPS d.sign® and IPS e.max Press® and were treated with hydrofluoric acid etching (HF), or HF+silane (S), or HF+S+adhesive or HF+S+A+resin cement. All samples were placed in a furnace at 650º for one minute in order to attempt to pyrolyze the composite. Each step was examined under scanning electron microscopy (SEM). Results: When the cleaning protocol had been performed, it left a clean and retentive surface. Conclusions: If the restoration is placed in a furnace at 650º for one minute, the composite cement will burn or pyrolyze and disappear, allowing conventional retreatment of the ceramic before rebonding. Key words:Ceramic, debond, surface treatment. PMID:25810843

  16. Carbon composite micro- and nano-tubes-based electrodes for detection of nucleic acids

    PubMed Central

    2011-01-01

    The first aim of this study was to fabricate vertically aligned multiwalled carbon nanotubes (MWCNTs). MWCNTs were successfully prepared by using plasma enhanced chemical vapour deposition. Further, three carbon composite electrodes with different content of carbon particles with various shapes and sizes were prepared and tested on measuring of nucleic acids. The dependences of adenine peak height on the concentration of nucleic acid sample were measured. Carbon composite electrode prepared from a mixture of glassy and spherical carbon powder and MWCNTs had the highest sensitivity to nucleic acids. Other interesting result is the fact that we were able to distinguish signals for all bases using this electrode. PMID:21711910

  17. Carbon composite micro- and nano-tubes-based electrodes for detection of nucleic acids.

    PubMed

    Prasek, Jan; Huska, Dalibor; Jasek, Ondrej; Zajickova, Lenka; Trnkova, Libuse; Adam, Vojtech; Kizek, Rene; Hubalek, Jaromir

    2011-01-01

    The first aim of this study was to fabricate vertically aligned multiwalled carbon nanotubes (MWCNTs). MWCNTs were successfully prepared by using plasma enhanced chemical vapour deposition. Further, three carbon composite electrodes with different content of carbon particles with various shapes and sizes were prepared and tested on measuring of nucleic acids. The dependences of adenine peak height on the concentration of nucleic acid sample were measured. Carbon composite electrode prepared from a mixture of glassy and spherical carbon powder and MWCNTs had the highest sensitivity to nucleic acids. Other interesting result is the fact that we were able to distinguish signals for all bases using this electrode. PMID:21711910

  18. Summary of the RHIC Retreat 2008

    SciTech Connect

    Pilat,F.; Brennan, M.; Brown, K.; Fischer, W.; Montag, C.

    2008-08-01

    The main goal of the RHIC Retreat is to review last run's performance and prepare for the next. As always though we also discussed the longer term goals and plans for the facility to put the work in perspective and in the right priority. A straw-man plan for the facility was prepared for the DOE that assumes 30 cryoweek and running 2 species per year. The plan outlines RHIC operations for 2008-2012 and integrates well accelerator and detector upgrades to optimize the physics output with high luminosities. The plans includes guidance from the PAC and has been reviewed by DOE.

  19. A Simple Demonstration of Carbon Dioxide Fixation and Acid Production in CAM Plants

    ERIC Educational Resources Information Center

    Walker, John R. L.; McWha, James A.

    1976-01-01

    Described is an experiment investigating carbon dioxide fixation in the dark and the diurnal rhythm of acid production in plants exhibiting Crassulacean Acid Metabolism. Included are suggestions for four further investigations. (SL)

  20. Increased fracture penetration and productivity using xanthan gelled acid in massive carbonate formations

    SciTech Connect

    Molon, J.P.; Fox, K.B.

    1983-03-01

    A measurable improvement in productivity can be achieved using xanthan gelled acid to stimulate carbonate formations. Well productivity results were compared to conventional acid fracture treatments. The significant improvements over classical acid fracturing techniques are due to the improved control of acid leakoff rates, retarded reaction rate and improved fracture width maintenance. The difficulties involved in acid fracturing massive Middle East carbonate formations are discussed and solutions are proposed using gelled acid technology. Some limitations in computer predictions of acid fracturing results are also discussed.

  1. An investigation of the effect of carbon support on ruthenium/carbon catalysts for lactic acid and butanone hydrogenation.

    PubMed

    Jones, Daniel R; Iqbal, Sarwat; Kondrat, Simon A; Lari, Giacomo M; Miedziak, Peter J; Morgan, David J; Parker, Stewart F; Hutchings, Graham J

    2016-06-29

    A series of ruthenium catalysts supported on two different carbons were tested for the hydrogenation of lactic acid to 1,2-propanediol and butanone to 2-butanol. The properties of the carbon supports were investigated by inelastic neutron scattering and correlated with the properties of the ruthenium deposited onto the carbons by wet impregnation or sol-immobilisation. It was noted that the rate of butanone hydrogenation was highly dependent on the carbon support, while no noticeable difference in rates was observed between different catalysts for the hydrogenation of lactic acid. PMID:27079275

  2. In situ synthesis carbonated hydroxyapatite layers on enamel slices with acidic amino acids by a novel two-step method.

    PubMed

    Wu, Xiaoguang; Zhao, Xu; Li, Yi; Yang, Tao; Yan, Xiujuan; Wang, Ke

    2015-09-01

    In situ fabrication of carbonated hydroxyapatite (CHA) remineralization layer on an enamel slice was completed in a novel, biomimetic two-step method. First, a CaCO3 layer was synthesized on the surface of demineralized enamel using an acidic amino acid (aspartic acid or glutamate acid) as a soft template. Second, at the same concentration of the acidic amino acid, rod-like carbonated hydroxyapatite was produced with the CaCO3 layer as a sacrificial template and a reactant. The morphology, crystallinity and other physicochemical properties of the crystals were characterized using field emission scanning electron microscopy (FESEM), Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD) and energy-dispersive X-ray analysis (EDAX), respectively. Acidic amino acid could promote the uniform deposition of hydroxyapatite with rod-like crystals via absorption of phosphate and carbonate ions from the reaction solution. Moreover, compared with hydroxyapatite crystals coated on the enamel when synthesized by a one-step method, the CaCO3 coating that was synthesized in the first step acted as an active bridge layer and sacrificial template. It played a vital role in orienting the artificial coating layer through the template effect. The results show that the rod-like carbonated hydroxyapatite crystals grow into bundles, which are similar in size and appearance to prisms in human enamel, when using the two-step method with either aspartic acid or acidic glutamate (20.00 mmol/L). PMID:26046278

  3. Electrochemical Determination of Glycoalkaloids Using a Carbon Nanotubes-Phenylboronic Acid Modified Glassy Carbon Electrode

    PubMed Central

    Wang, Huiying; Liu, Mingyue; Hu, Xinxi; Li, Mei; Xiong, Xingyao

    2013-01-01

    A versatile strategy for electrochemical determination of glycoalkaloids (GAs) was developed by using a carbon nanotubes-phenylboronic acid (CNTs-PBA) modified glassy carbon electrode. PBA reacts with α-solanine and α-chaconine to form a cyclic ester, which could be utilized to detect GAs. This method allowed GA detection from 1 μM to 28 μM and the detection limit was 0.3 μM. Affinity interaction of GAs and immobilized PBA caused an essential change of the peak current. The CNT-PBA modified electrodes were sensitive for detection of GAs, and the peak current values were in quite good agreement with those measured by the sensors. PMID:24287539

  4. One carbon metabolism in anaerobic bacteria: Regulation of carbon and electron flow during organic acid production

    SciTech Connect

    Zeikus, J.G.; Jain, M.

    1993-12-31

    The project deals with understanding the fundamental biochemical mechanisms that physiologically control and regulate carbon and electron flow in anaerobic chemosynthetic bacteria that couple metabolism of single carbon compounds and hydrogen to the production of organic acids (formic, acetic, butyric, and succinic) or methane. The authors compare the regulation of carbon dioxide and hydrogen metabolism by fermentation, enzyme, and electron carrier analysis using Butyribacterium methylotrophicum, Anaeroblospirillum succiniciproducens, Methanosarcina barkeri, and a newly isolated tri-culture composed of a syntrophic butyrate degrader strain IB, Methanosarcina mazei and Methanobacterium formicicum as model systems. To understand the regulation of hydrogen metabolism during butyrate production or acetate degradation, hydrogenase activity in B. methylotrophicum or M. barkeri is measured in relation to growth substrate and pH; hydrogenase is purified and characterized to investigate number of hydrogenases; their localization and functions; and, their sequences are determined. To understand the mechanism for catabolic CO{sub 2} fixation to succinate the PEP carboxykinase enzyme and gene of A. succiniciproducens are purified and characterized. Genetically engineered strains of Escherichia coli containing the phosphoenolpyruvate (PEP) carboxykinase gene are examined for their ability to produce succinate in high yield. To understand the mechanism of fatty acid degradation by syntrophic acetogens during mixed culture methanogenesis formate and hydrogen production are characterized by radio tracer studies. It is intended that these studies provide strategies to improve anaerobic fermentations used for the production of organic acids or methane and, new basic understanding on catabolic CO{sub 2} fixation mechanisms and on the function of hydrogenase in anaerobic bacteria.

  5. USE OF STABLE CARBON ISOTOPE RATIOS OF FATTY ACIDS TO EVALUATE MICROBIAL CARBON SOURCES IN TERRESTRIAL ENVIRONMENTS

    EPA Science Inventory

    We use measurements of the concentration and stable carbon isotopic ratio (D 13C) of individual microbial phospholipid fatty acids (PLFAs) in soils as indicators of live microbial biomass levels and microbial carbon source. We found that intensive sugar cane cultivation leads to ...

  6. USE OF THE COMPOSITION AND STABLE CARBON ISOTOPE RATIO OF MICROBIAL FATTY ACIDS TO STUDY CARBON CYCLING

    EPA Science Inventory

    We use measurements of the concentration and stable carbon isotopic ratio (Gamma 13C) of individual microbial phospholipid fatty acids (PLFAS) in soils and sediments as indicators of live microbial biomass levels and microbial carbon source. For studies of soil organic matter (SO...

  7. Electrochemical formation of hydroxide for enhancing carbon dioxide and acid gas uptake by a solution

    DOEpatents

    Rau, Gregory Hudson

    2014-07-01

    A system for forming metal hydroxide from a metal carbonate utilizes a water electrolysis cell having an acid-producing anode and a hydroxyl-producing cathode immersed in a water solution of sufficient ionic content to allow an electric current to pass between the hydroxyl-producing cathode and the acid-producing anode. A metal carbonate is placed in close proximity to the acid-producing anode. A direct current electrical voltage is provided across the acid-producing anode and the hydroxyl-producing cathode sufficient to generate acid at the acid-producing anode and hydroxyl ions at the hydroxyl-producing cathode. The acid dissolves at least part of the metal carbonate into metal and carbonate ions allowing the metal ions to travel toward the hydroxyl-producing cathode and to combine with the hydroxyl ions to form the metal hydroxide. The carbonate ions travel toward the acid-producing anode and form carbonic acid and/or water and carbon dioxide.

  8. Latest Word on Retreat of the West Antarctic Ice Sheet

    NASA Technical Reports Server (NTRS)

    Bindschadler, R.

    2000-01-01

    The West Antarctic ice sheet during the Last Glacial Maximum (LGM) is estimated to have been three times its present volume and to have extended close to the edge of the continental shelf Holocene retreat of this ice sheet in the Ross Sea began between 11,000 and 12,000 years ago. This history implies an average contribution of this ice sheet to sea level of 0.9 mm/a. Evidence of dateable past grounding line positions in the Ross sector are broadly consistent with a linear retreat model. However, inferred rates of retreat for some of these grounding line positions are not consistent with a linear retreat model. More rapid retreat approximately 7600 years ago and possible near-stability in the Ross Sea sector at present suggest a slow rate of initial retreat followed by a more rapid-than-average retreat during the late Holocene, returning to a near-zero rate of retreat currently. This model is also consistent with the mid-Holocene high stand observations of eustatic sea level. Recent compilation of Antarctic bed elevations (BEDMAP) illustrates that the LGM and present grounding lines occur in the shallowest waters, further supporting the model of a middle phase of rapid retreat bracketed by an older and a more recent phase of modest retreat. Extension of these hypotheses into the future make subsequent behavior of the West Antarctic ice sheet more difficult to predict but suggest that if it loses its hold on the present shallow bed, the final retreat of the ice sheet could be very rapid.

  9. Novel graphene flowers modified carbon fibers for simultaneous determination of ascorbic acid, dopamine and uric acid.

    PubMed

    Du, Jiao; Yue, Ruirui; Ren, Fangfang; Yao, Zhangquan; Jiang, Fengxing; Yang, Ping; Du, Yukou

    2014-03-15

    A novel and sensitive carbon fiber electrode (CFE) modified by graphene flowers was prepared and used to simultaneously determine ascorbic acid (AA), dopamine (DA) and uric acid (UA). SEM images showed that beautiful and layer-petal graphene flowers homogeneously bloomed on the surface of CFE. Moreover, sharp and obvious oxidation peaks were found at the obtained electrode when compared with CFE and glassy carbon electrode (GCE) for the oxidation of AA, DA and UA. Also, the linear calibration plots for AA, DA and UA were observed, respectively, in the ranges of 45.4-1489.23 μM, 0.7-45.21 μM and 3.78-183.87 μM in the individual detection of each component. By simultaneously changing the concentrations of AA, DA and UA, their oxidation peaks appeared at -0.05 V, 0.16 V and 2.6 V, and the good linear responses ranges were 73.52-2305.53 μM, 1.36-125.69 μM and 3.98-371.49 μM, respectively. In addition, the obtained electrode showed satisfactory results when applied to the determination of AA, DA and UA in urine and serum samples. PMID:24140872

  10. Fate of microbial nitrogen, carbon, hydrolysable amino acids, monosaccharides, and fatty acids in sediment

    NASA Astrophysics Data System (ADS)

    Veuger, Bart; van Oevelen, Dick; Middelburg, Jack J.

    2012-04-01

    The fate of microbial carbon, nitrogen, hydrolysable amino acids (HAAs), monosaccharides, and fatty acids in sediment was investigated experimentally. The microbial community of a tidal flat sediment was labeled with 13C-enriched glucose and 15N-enriched ammonium, and sediment was incubated for up to 371 days. Analysis of total concentrations and 13C- and 15N content of bulk sediment, hydrolysable amino acids (including D-alanine), monosaccharides, total fatty acids (TFAs), and phospholipid-derived fatty acids (PLFAs) allowed us to trace the fate of microbial biomass and -detritus and the major biochemical groups therein (proteins, carbohydrates, and lipids) over intermediate time scales (weeks-months). Moreover, the unidentified fraction of the labeled material (i.e. not analyzed as HAA, FA, or carbohydrate) provided information on the formation and fate of molecularly uncharacterizable organic matter. Loss of 13C and 15N from the sediment was slow (half live of 433 days) which may have been due to the permanently anoxic conditions in the experiment. Loss rates for the different biochemical groups were also low with the following order of loss rate constants: PLFA > TFA > HAA > monosaccharides. The unidentified 13C-pool was rapidly formed (within days) and then decreased relatively slowly, resulting in a gradual relative accumulation of this pool over time. Degradation and microbial reworking of the labeled material resulted in subtle, yet consistent, diagenetic changes within the different biochemical groups. In the HAA pool, glycine, lysine, and proline were lost relatively slowly (i.e. best preserved) while there was no accumulation of D-alanine relative to L-alanine, indicating no relative accumulation of bacterial macromolecules rich in D-alanine. In the fatty acid pool, there was very little difference between PLFAs and TFAs, indicating a very similar lability of these pools. Differences between individual fatty acids included a relatively slow loss of i15

  11. Age Estimates of Holocene Glacial Retreat in Lapeyrère Bay, Anvers Island, Antarctica

    NASA Astrophysics Data System (ADS)

    Mead, K. A.; Wellner, J. S.; Rosenheim, B. E.

    2011-12-01

    Lapeyrère Bay is a fjord on the eastern side of Anvers Island, located off the Western Antarctic Peninsula. Anvers island has a maximum elevation of 2400m (comprised of ice overlaying bedrock), and experiences colder temperatures and more precipitation than the South Shetlands, which are ~230km to the north. Two glaciers enter Lapeyrère Bay, one large and vulnerable to avalanching, the Iliad Glacier, and one smaller glacier confined to a northern unnamed cove. Though several research cruises have visited Lapeyrère Bay, very little has been published on the fjord's glacial retreat history or sediment flux. The primary purpose of this study is to reconstruct the glacial retreat and sediment flux histories of Lapeyrère Bay using a SHALDRIL core and standard piston cores for chronology and sedimentary facies analysis, and multibeam swath bathymetry data for identifying seafloor morphological features. Preliminary core data from the proximal northern flank of Lapeyrère Bay show greenish grey sandy mud with scattered pebble and sand lens lithology. A core taken in the distal-most part of the fjord is largely diatomaceous sediment grading into grey silty mud with thin sandy turbidites. Multibeam data has exposed seafloor features including a grounding zone wedge at the entrance of the unnamed cove of northern Lapeyrère Bay, drumlins, glacial lineations, and a glacial outwash fan near the ocean-termination of the Iliad glacier. Additionally, this study seeks to assess the effectiveness of a novel 14C method of dating sediment lacking sufficient calcareous material for carbonate 14C dating. The method being tested is ramped pyrolysis radiocarbon analysis, which dates individual fractions of organic material. It is hypothesized that ramped pyrolysis will improve upon bulk acid insoluble organic material (AIOM) dating, as AIOM can include both autochthonous syndepositionally aged carbon and allochthonous pre-aged carbon, resulting in 14C ages inherently older than the

  12. Simultaneous inhibition of carbon and nitrogen mineralization in a forest soil by simulated acid precipitation

    SciTech Connect

    Klein, T.M.; Novick, N.J.; Kreitinger, J.P.; Alexander, M.

    1984-06-01

    One method to simulate the long-term exposure of soil to acid rain involves the addition of single doses of concentrated acid. The inhibition of carbon mineralization accompanied by a stimulation of nitrogen mineralization may result from this severe, unnatural treatment. The present study was designed to determine whether the inhibition of carbon mineralization and the accompanying enhanced nitrogen mineralization would occur when soils are treated with more dilute acid for long periods of time, as takes place in nature.

  13. Sorption of perfluorooctanoic acid, perfluorooctane sulfonate and perfluoroheptanoic acid on granular activated carbon.

    PubMed

    Zhang, Di; Luo, Qi; Gao, Bin; Chiang, Sheau-Yun Dora; Woodward, David; Huang, Qingguo

    2016-02-01

    The sorption of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and perfluoroheptanoic acid (PFHpA) on granular activated carbon (GAC) was characterized and compared to explore the underlying mechanisms. Sorption of the three perfluoroalkyl acids (PFAAs) on GAC appeared to be a rapid intra-particle diffusion process, which were well represented by the pseudo-second-order rate model with the sorption rate following the order PFOS > PFOA > PFHpA. Sorption isotherm data were well fitted by the Freundlich model with the sorption capacity (Kf) of PFOS, PFOA and PFHpA being 4.45, 2.42 and 1.66 respectively. This suggests that the hydrophilic head group on PFAAs, i.e. sulfonate vs carboxylic, has a strong influence on their sorption. Comparison between PFOA and PFHpA revealed that hydrophobicity could also play a role in the sorption of PFAAs on GAC when the fluorocarbon chain length is different. Analyses using Attenuated Total Reflection (ATR)-Fourier Transform Infrared (FTIR) spectroscopy suggested possible formation of a negative charge-assisted H-bond between PFAAs and the functionalities on GAC surfaces, including non-aromatic ketones, sulfides, and halogenated hydrocarbons. PMID:26606188

  14. Screen printing of nucleic acid detecting carbon electrodes.

    PubMed

    Dequaire, Murielle; Heller, Adam

    2002-09-01

    A large fraction of the presently mass-manufactured (> 10(8) units/year) electrochemical biosensors, used mostly by diabetic people to monitor their blood glucose levels, have screen-printed carbon working electrodes. An earlier study (Campbell, C. N., et al. Anal. Chem. 2002, 74, 158-162) showed that nucleic acids can be assayed at 1 nM concentrations by a sandwich-type amperometric method. The assay was performed with vitreous carbon working electrodes on which an electron-conducting polycationic redox polymer and avidin were coelectrodeposited. Because the rate of the electrodeposition increases with the surface density of the polycationic redox polymer, its practicality depends on pretreatment of the surface, which adds anionic functions. (Gao, Z., et al. Angew. Chem. Int. Ed. 2002, 41, 810-813). Here it is shown that the required conducting redox polymer films can be electrodeposited on potentially mass manufacturable electrodes made by screen-printing hydrophilic carbon inks on polyester sheets. The modified electrodes are made in two steps. First a polycationic electron-conducting redox polymer is cross-linked and electrodeposited by applying a negative potential. Next, an amine-terminated 20-base single-stranded oligonucleotide is electrodeposited by ligand-exchange. Both steps involve exchange of a labile inner sphere chloride ligand of the polymer-bound osmium-complex: Cross-linking and electrodeposition of the redox polymer result when inner-sphere chloride anions of the osmium complexes are exchanged by imidazole functions of neighboring chains. Incorporation of the oligonucleotide in the redox polymer results in the formation of a coordinative bond between the terminal amine (attached through a spacer to the oligonucleotide) and the osmium complex. In testing for the presence of a 38-base oligonucleotide, the analyte, in a 15- or 25-microL droplet of hybridization solution, is hybridized with and captured by the 20-base electrode-bound sequence; then

  15. Sequestering CO(2) by mineral carbonation: stability against acid rain exposure.

    PubMed

    Allen, Daniel J; Brent, Geoff F

    2010-04-01

    Mineral carbonation is a potentially attractive alternative to storage of compressed CO(2) in underground repositories, known as geosequestration. Processes for the conversion of basic ores, such as magnesium silicates, to carbonates have been proposed by various researchers, with storage of the carbonate as backfill in the original mine representing a solid carbon sink. The stability of such carbon sinks against acid rain and other sources of strong acids is examined here. It is acknowledged that in the presence of strong acid, carbonates will dissolve and release carbon dioxide. A sensitivity analysis covering annual average rainfall and pH that may be encountered in industrialized areas of the United States, China, Europe, and Australia was conducted to determine maximum CO(2) rerelease rates from mineral carbonation carbon sinks. This analysis is based on a worst-case premise that is equivalent to assuming infinitely rapid kinetics of dissolution of the carbonate. The analysis shows that under any likely conditions of pH and rainfall, leakage rates of stored CO(2) are negligible. This is illustrated in a hypothetical case study under Australian conditions. It is thus proposed that sequestration by mineral carbonation can be considered to be permanent on practical human time scales. Other possible sources of acid have also been considered. PMID:20199068

  16. The Formation and Stability of Carbonic Acid on Outer Solar System Bodies

    NASA Technical Reports Server (NTRS)

    Peeters, Z.; Hudson, R. L.; Moore, M. H.; Lewis, Ariel

    2009-01-01

    The radiation chemistry, thermal stability, and vapor pressure of solid-phase carbonic acid (H2CO3) have been studied with mid-infrared spectroscopy. A new procedure for measuring this molecule's radiation stability has been used to obtain intrinsic IR band strengths and half-lives for radiolytic destruction. Results are compared to literature values. We report, for the first time, measurements of carbonic acid's vapor pressure and its heat of sublimation. We also report the first observation of a chemical reaction involving solid-phase carbonic acid. Possible applications of these findings are discussed, with an emphasis on the outer Solar System.

  17. Student Leadership Retreat Focusing on a Commitment to Excellence

    PubMed Central

    Traynor, Andrew P.; Sorensen, Todd D.

    2009-01-01

    Objective To design and evaluate a student leadership retreat focused on: leadership regardless of position or title, the need for passionate commitment to excellence, the importance of teamwork, and the value of self-reflection. Design Students in their second, third, and fourth year of a doctor of pharmacy (PharmD) program were invited to participate in an off-campus leadership retreat that combined organized learning activities and social/networking opportunities. Retreat content utilized didactic, experiential, and self-directed learning activities. Assessment Forty-two students participated in the retreat and were surveyed pre- and post-retreat. A student-led group evaluation and course evaluations were also utilized. Responses on the post-retreat evaluation suggested an increased belief in their ability to influence change and an enhanced awareness of the role of self-reflection in creating excellence in the profession. Conclusion An off-campus overnight retreat has value in challenging student perceptions about leadership and promoting reflection on their personal role in leading change within the profession Continued exploration and development of this format is warranted for commitment to excellence programming and also for additional leadership topics and audiences. PMID:19564991

  18. Modelling Glacier Retreat after Ice Shelf Collapse

    NASA Astrophysics Data System (ADS)

    De Rydt, J.; Gudmundsson, G. H.; Rott, H.; Bamber, J. L.

    2014-12-01

    Satellite measurements have shown the consistent and ongoing speed-up and retreat of glaciers that were once buttressed by the collapsed Larsen B ice shelf. Understanding the response of grounded ice to ice shelf collapse is a prerequisite to future predictions of sea level rise as other ice shelfs such as Scar Inlet or the Larsen Ice Shelf further weaken due to changing atmospheric and ocean conditions.We present model results for a number of sensitivity experiments that aim to simulate the response of glaciers to the collapse of Larsen B. For this purpose we use a state of the art shallow shelf model with grounding line resolving capabilities. The model is initialized to observed pre-2002 conditions with the ice shelf in place, and transient runs are done that study the response to a weakening and removal of the ice shelf. Results are compared to a novel dataset of observed ice velocities, which provides the most comprehensive overview of dynamical changes after the collapse to-date. In addition, we investigate glacier response to the future collapse of Scar Inlet, a remnant of the Larsen B ice shelf which has been suggested to show signs of weakening in recent years. Results will also be used to inform a future Antartic Peninsula-wide modelling study.

  19. Seaweed communities in retreat from ocean warming.

    PubMed

    Wernberg, Thomas; Russell, Bayden D; Thomsen, Mads S; Gurgel, C Frederico D; Bradshaw, Corey J A; Poloczanska, Elvira S; Connell, Sean D

    2011-11-01

    In recent decades, global climate change [1] has caused profound biological changes across the planet [2-6]. However, there is a great disparity in the strength of evidence among different ecosystems and between hemispheres: changes on land have been well documented through long-term studies, but similar direct evidence for impacts of warming is virtually absent from the oceans [3, 7], where only a few studies on individual species of intertidal invertebrates, plankton, and commercially important fish in the North Atlantic and North Pacific exist. This disparity of evidence is precarious for biological conservation because of the critical role of the marine realm in regulating the Earth's environmental and ecological functions, and the associated socioeconomic well-being of humans [8]. We interrogated a database of >20,000 herbarium records of macroalgae collected in Australia since the 1940s and documented changes in communities and geographical distribution limits in both the Indian and Pacific Oceans, consistent with rapid warming over the past five decades [9, 10]. We show that continued warming might drive potentially hundreds of species toward and beyond the edge of the Australian continent where sustained retreat is impossible. The potential for global extinctions is profound considering the many endemic seaweeds and seaweed-dependent marine organisms in temperate Australia. PMID:22036178

  20. Calculating lunar retreat rates using tidal rhythmites

    USGS Publications Warehouse

    Kvale, E.P.; Johnson, H.W.; Sonett, C.P.; Archer, A.W.; Zawistoski, A.N.N.

    1999-01-01

    Tidal rhythmites are small-scale sedimenta??r}- structures that can preserve a hierarchy of astronomically induced tidal periods. They can also preserve a record of periodic nontidal sedimentation. If properly interpreted and understood, tidal rhjthmites can be an important component of paleoastronomy and can be used to extract information on ancient lunar orbital dynamics including changes in Earth-Moon distance through geologic time. Herein we present techniques that can be used to calculate ancient Earth-Moon distances. Each of these techniques, when used on a modern high-tide data set, results in calculated estimates of lunar orbital periods and an EarthMoon distance that fall well within 1 percent of the actual values. Comparisons to results from modern tidal data indicate that ancient tidal rhythmite data as short as 4 months can provide suitable estimates of lunar orbital periods if these tidal records are complete. An understanding of basic tidal theory allows for the evaluation of completeness of the ancient tidal record as derived from an analysis of tidal rhythmites. Utilizing the techniques presented herein, it appears from the rock record that lunar orbital retreat slowed sometime during the midPaleozoic. Copyright ??1999, SEPM (Society for Sedimentary Geology).

  1. Sulfonated mesoporous silica-carbon composites and their use as solid acid catalysts

    NASA Astrophysics Data System (ADS)

    Valle-Vigón, Patricia; Sevilla, Marta; Fuertes, Antonio B.

    2012-11-01

    The synthesis of highly functionalized porous silica-carbon composites made up of sulfonic groups attached to a carbon layer coating the pores of three types of mesostructured silica (i.e. SBA-15, KIT-6 and mesocellular silica) is presented. The synthesis procedure involves the following steps: (a) removal of the surfactant, (b) impregnation of the silica pores with a carbon precursor, (c) carbonization and (d) sulfonation. The resulting silica-carbon composites contain ˜30 wt % of carbonaceous matter with a high density of acidic groups attached to the deposited carbon (i.e.sbnd SO3H, sbnd COOH and sbnd OH). The structural characteristics of the parent silica are retained in the composite materials, which exhibit a high surface area, a large pore volume and a well-ordered porosity made up uniform mesopores. The high density of the sulfonic groups in combination with the mesoporous structure of the composites ensures that a large number of active sites are easily accessible to reactants. These sulfonated silica-carbon composites behave as eco-friendly, active, selective, water tolerant and recyclable solid acids. In this study we demonstrate the usefulness of these composites as solid acid catalysts for the esterification of maleic anhydride, succinic acid and oleic acid with ethanol. These composites exhibit a superior intrinsic catalytic activity to other commercial solid acids such as Amberlyst-15.

  2. Humic acid adsorption on fly ash and its derived unburned carbon.

    PubMed

    Wang, Shaobin; Zhu, Z H

    2007-11-01

    Fly ash is solid waste from combustion process, containing oxide minerals and unburned carbon. In this investigation, fly ash has been separated into metal oxide mineral section and unburned carbon. The fly ash with different contents of unburned carbon was employed for humic acid adsorption to investigate the influence of unburned carbon on adsorption. It is found that metal oxides and unburned carbon in fly ash exhibit significant difference in humic acid adsorption. The unburned carbon plays the major role in adsorption. Higher content of unburned carbon in fly ash results in higher surface area and thus higher humic acid adsorption. Fly ash and unburned carbon exhibit adsorption capacity of humic acid of 11 and 72 mg/g, respectively, at 30 degrees C, pH 7. Humic acid adsorption is also affected by ion strength, pH, and temperature. The thermodynamic calculations indicate that the adsorption is endothermic nature with DeltaH(0) and DeltaS(0) as 5.79 kJ/mol and 16.0 J/K mol, respectively. PMID:17628583

  3. Morphology-dependent Electrochemical Enhancements of Porous Carbon as Sensitive Determination Platform for Ascorbic Acid, Dopamine and Uric Acid

    NASA Astrophysics Data System (ADS)

    Cheng, Qin; Ji, Liudi; Wu, Kangbing; Zhang, Weikang

    2016-02-01

    Using starch as the carbon precursor and different-sized ZnO naoparticles as the hard template, a series of porous carbon materials for electrochemical sensing were prepared. Experiments of scanning electron microscopy, transmission electron microscopy and Nitrogen adsorption-desorption isotherms reveal that the particle size of ZnO has big impacts on the porous morphology and surface area of the resulting carbon materials. Through ultrasonic dispersion of porous carbon and subsequent solvent evaporation, different sensing interfaces were constructed on the surface of glassy carbon electrode (GCE). The electrochemical behaviors of ascorbic acid (AA), dopamine (DA) and uric acid (UA) were studied. On the surface of porous carbon materials, the accumulation efficiency and electron transfer ability of AA, DA and UA are improved, and consequently their oxidation signals enhance greatly. Moreover, the interface enhancement effects of porous carbon are also controlled by the particle size of hard template. The constructed porous carbon interface displays strong signal amplification ability and holds great promise in constructing a sensitive platform for the simultaneous determination of AA, DA and UA.

  4. Morphology-dependent Electrochemical Enhancements of Porous Carbon as Sensitive Determination Platform for Ascorbic Acid, Dopamine and Uric Acid

    PubMed Central

    Cheng, Qin; Ji, Liudi; Wu, Kangbing; Zhang, Weikang

    2016-01-01

    Using starch as the carbon precursor and different-sized ZnO naoparticles as the hard template, a series of porous carbon materials for electrochemical sensing were prepared. Experiments of scanning electron microscopy, transmission electron microscopy and Nitrogen adsorption-desorption isotherms reveal that the particle size of ZnO has big impacts on the porous morphology and surface area of the resulting carbon materials. Through ultrasonic dispersion of porous carbon and subsequent solvent evaporation, different sensing interfaces were constructed on the surface of glassy carbon electrode (GCE). The electrochemical behaviors of ascorbic acid (AA), dopamine (DA) and uric acid (UA) were studied. On the surface of porous carbon materials, the accumulation efficiency and electron transfer ability of AA, DA and UA are improved, and consequently their oxidation signals enhance greatly. Moreover, the interface enhancement effects of porous carbon are also controlled by the particle size of hard template. The constructed porous carbon interface displays strong signal amplification ability and holds great promise in constructing a sensitive platform for the simultaneous determination of AA, DA and UA. PMID:26924080

  5. Morphology-dependent Electrochemical Enhancements of Porous Carbon as Sensitive Determination Platform for Ascorbic Acid, Dopamine and Uric Acid.

    PubMed

    Cheng, Qin; Ji, Liudi; Wu, Kangbing; Zhang, Weikang

    2016-01-01

    Using starch as the carbon precursor and different-sized ZnO naoparticles as the hard template, a series of porous carbon materials for electrochemical sensing were prepared. Experiments of scanning electron microscopy, transmission electron microscopy and Nitrogen adsorption-desorption isotherms reveal that the particle size of ZnO has big impacts on the porous morphology and surface area of the resulting carbon materials. Through ultrasonic dispersion of porous carbon and subsequent solvent evaporation, different sensing interfaces were constructed on the surface of glassy carbon electrode (GCE). The electrochemical behaviors of ascorbic acid (AA), dopamine (DA) and uric acid (UA) were studied. On the surface of porous carbon materials, the accumulation efficiency and electron transfer ability of AA, DA and UA are improved, and consequently their oxidation signals enhance greatly. Moreover, the interface enhancement effects of porous carbon are also controlled by the particle size of hard template. The constructed porous carbon interface displays strong signal amplification ability and holds great promise in constructing a sensitive platform for the simultaneous determination of AA, DA and UA. PMID:26924080

  6. Molten Carbonate and Phosphoric Acid Stationary Fuel Cells: Overview and Gap Analysis

    SciTech Connect

    Remick, R.; Wheeler, D.

    2010-09-01

    This report describes the technical and cost gap analysis performed to identify pathways for reducing the costs of molten carbonate fuel cell (MCFC) and phosphoric acid fuel cell (PAFC) stationary fuel cell power plants.

  7. Imprinted zeolite modified carbon paste electrode as a potentiometric sensor for uric acid

    NASA Astrophysics Data System (ADS)

    Khasanah, Miratul; Widati, Alfa Akustia; Fitri, Sarita Aulia

    2016-03-01

    Imprinted zeolite modified carbon paste electrode (carbon paste-IZ) has been developed and applied to determine uric acid by potentiometry. The imprinted zeolite (IZ) was synthesized by the mole ratio of uric acid/Si of 0.0306. The modified electrode was manufactured by mass ratio of carbon, IZ and solid paraffin was 40:25:35. The modified electrode had shown the measurement range of 10-5 M to 10-2 M with Nernst factor of 28.6 mV/decade, the detection limit of 5.86 × 10-6 M and the accuracy of 95.3 - 105.0%. Response time of the electrode for uric acid 10-5 M - 10-2 M was 25 - 44 s. The developed electrode showed the high selectivity toward uric acid in the urea matrix. Life time of the carbon paste-IZ electrode was 10 weeks.

  8. Determination of primary and secondary sources of organic acids and carbonaceous aerosols using stable carbon isotopes

    NASA Astrophysics Data System (ADS)

    Fisseha, Rebeka; Saurer, Matthias; Jäggi, Maya; Siegwolf, Rolf T. W.; Dommen, Josef; Szidat, Sönke; Samburova, Vera; Baltensperger, Urs

    Stable carbon isotope ratio ( δ13C) data can provide important information regarding the sources and the processing of atmospheric organic carbon species. Formic, acetic and oxalic acid were collected from Zurich city in August-September 2002 and March 2003 in the gas and aerosol phase, and the corresponding δ13C analysis was performed using a wet oxidation method followed by isotope ratio mass spectrometry. In August, the δ13C values of gas phase formic acid showed a significant correlation with ozone (coefficient of determination ( r2) = 0.63) due to the kinetic isotope effect (KIE). This indicates the presence of secondary sources (i.e. production of organic acids in the atmosphere) in addition to direct emission. In March, both gaseous formic and acetic acid exhibited similar δ13C values and did not show any correlation with ozone, indicating a predominantly primary origin. Even though oxalic acid is mainly produced by secondary processes, the δ13C value of particulate oxalic acid was not depleted and did not show any correlation with ozone, which may be due to the enrichment of 13C during the gas - aerosol partitioning. The concentrations and δ13C values of the different aerosol fractions (water soluble organic carbon, water insoluble organic carbon, carbonate and black carbon) collected during the same period were also determined. Water soluble organic carbon (WSOC) contributed about 60% to the total carbon and was enriched in 13C compared to other fractions indicating a possible effect of gas - aerosol partitioning on δ13C of carbonaceous aerosols. The carbonate fraction in general was very low (3% of the total carbon).

  9. A Functional Tricarboxylic Acid Cycle Operates during Growth of Bordetella pertussis on Amino Acid Mixtures as Sole Carbon Substrates

    PubMed Central

    Garnier, Dominique; Speck, Denis

    2015-01-01

    It has been claimed that citrate synthase, aconitase and isocitrate dehydrogenase activities are non-functional in Bordetella pertussis and that this might explain why this bacterium’s growth is sometimes associated with accumulation of polyhydroxybutyrate (PHB) and/or free fatty acids. However, the sequenced genome includes the entire citric acid pathway genes. Furthermore, these genes were expressed and the corresponding enzyme activities detected at high levels for the pathway when grown on a defined medium imitating the amino acid content of complex media often used for growth of this pathogenic microorganism. In addition, no significant PHB or fatty acids could be detected. Analysis of the carbon balance and stoichiometric flux analysis based on specific rates of amino acid consumption, and estimated biomass requirements coherent with the observed growth rate, clearly indicate that a fully functional tricarboxylic acid cycle operates in contrast to previous reports. PMID:26684737

  10. Stable carbon isotopic compositions of low-molecular-weight dicarboxylic acids, oxocarboxylic acids, α-dicarbonyls, and fatty acids: Implications for atmospheric processing of organic aerosols

    NASA Astrophysics Data System (ADS)

    Zhang, Yan-Lin; Kawamura, Kimitaka; Cao, Fang; Lee, Meehye

    2016-04-01

    Stable carbon isotopic compositions (δ13C) were measured for 23 individual organic species including 9 dicarboxylic acids, 7 oxocarboxylic acids, 1 tricarboxylic acid, 2 α-dicarbonyls, and 4 fatty acids in the aerosols from Gosan background site in East Asia. δ13C values of particle phase glyoxal and methylglyoxal are significantly larger than those previously reported for isoprene and other precursors. The values are consistently less negative in oxalic acid (C2, average -14.1‰), glyoxylic acid (-13.8‰), pyruvic acid (-19.4‰), glyoxal (-13.5‰), and methylglyoxal (-18.6‰) compared to other organic species (e.g., palmitic acid, -26.3‰), which can be explained by the kinetic isotope effects during atmospheric oxidation of pre-aged precursors (e.g., isoprene) and the subsequent gas-particle partitioning after the evaporation of clouds or wet aerosols. The δ13C values of C2 is positively correlated with C2 to organic carbon ratio, indicating that photochemical production of C2 is more pronounced than its degradation during long-range atmospheric transport. The isotopic results also suggest that aqueous phase oxidation of glyoxal and methylglyoxal is a major formation process of oxalic acid via the intermediates such as glyoxylic acid and pyruvic acid. This study provides evidence that organic aerosols are intensively photochemically aged in the western North Pacific rim.

  11. How fast do gully headcuts retreat?

    NASA Astrophysics Data System (ADS)

    Vanmaercke, Matthias; Poesen, Jean

    2015-04-01

    Gullies can be a dominant sediment source at field and catchment scales. Over the past decades, several studies have been conducted that quantify gully headcut retreat (GHR) in different environments. Although this led to important site-specific and regional insights, the overall importance of this erosion process or the factors that control it at a global scale remain poorly understood. This study aims to bridge this gap by conducting a meta-analysis of measured GHR rates worldwide. Through an extensive literature review, GHR rates for ca. 900 individual actively retreating gullies (comprising a total measuring period of > 19 000 years) from more than 50 study areas worldwide have been compiled. Each GHR rate was measured by means of repeated field surveys and/or analyses of aerial photographs over a period of at least one year. The collected data shows a very large variability, both in terms of gully dimensions (cross-sectional areas ranging between 0.11 and 816 m² with a median of 4 m²) and GHR rates (ranging between 0.003 and 47 000 m³/y with a median of 2.2 m³/y). Linear GHR rates vary between 0.01 and 70 m/y (median: 0.82 m/y). By means of statistical analyses for a subset of 689 gullies with a known contributing area, we explored which factors are most relevant in explaining the observed 6 orders of magnitudes of variation in volumetric GHR rates. Results show that measured GHR rates are significantly correlated to the runoff contributing area of the gully (r² = 0.13) and the average rainfall depth on a rainy day (i.e. the long-term average annual rainfall depth divided by the average number of rainy days; r² = 0.39). Combined, these two factors explained 57% of the observed variability in average GHR rates. Other factors (e.g. land use or soil type) showed no significant correlation with the observed GHR rates. This may be attributed to the uncertainties associated with accurately quantifying these factors. In addition, a large part of the remaining

  12. Rituximab Retreatment for Low-Tumor Burden Follicular Lymphoma

    Cancer.gov

    A summary of results from a randomized clinical trial of patients with low–tumor burden follicular lymphoma that compared maintenance therapy with rituximab versus retreatment with rituximab only when there was evidence of disease progression.

  13. USE OF THE COMPOSITION AND STABLE CARBONIISOTOPE RATIO OF MICROBIAL FATTY ACIDS TO STUDY CARBON CYCLING

    EPA Science Inventory

    We use measurements of the concentration and stable carbon isotopic ratio (*13C) of individual microbial phospholipid fatty acids (PLFAs) in soils and sediments as indicators of live microbial biomass levels and microbial carbon source. For studies of soil organic matter (SOM) cy...

  14. Parallel retreat of rock slopes underlain by alternation of strata

    NASA Astrophysics Data System (ADS)

    Imaizumi, Fumitoshi; Nishii, Ryoko; Murakami, Wataru; Daimaru, Hiromu

    2015-06-01

    Characteristic landscapes (e.g., cuesta, cliff and overhang of caprock, or stepped terrain) formed by differential erosion can be found in areas composed of variable geology exhibiting different resistances to weathering. Parallel retreat of slopes, defined as recession of slopes without changes in their topography, is sometimes observed on slopes composed of multiple strata. However, the conditions needed for such parallel retreat have not yet been sufficiently clarified. In this study, we elucidated the conditions for parallel retreat of rock slopes composed of alternating layers using a geometric method. In addition, to evaluate whether various rock slopes fulfilled the conditions for parallel retreat, we analyzed topographic data obtained from periodic measurement of rock slopes in the Aka-kuzure landslide, central Japan. Our geometric analysis of the two-dimensional slopes indicates that dip angle, slope gradient, and erosion rate are the factors that determine parallel retreat conditions. However, dip angle does not significantly affect parallel retreat conditions in the case of steep back slopes (slope gradient > 40°). In contrast, dip angle is an important factor when we consider the parallel retreat conditions in dip slopes and gentler back slopes (slope gradient < 40°). Geology in the Aka-kuzure landslide is complex because of faulting, folding, and toppling, but spatial distribution of the erosion rate measured by airborne LiDAR scanning and terrestrial laser scanning (TLS) roughly fulfills parallel retreat conditions. The Aka-kuzure landslide is characterized by repetition of steep sandstone cliffs and gentle shale slopes that form a stepped topography. The inherent resistance of sandstone to weathering is greater than that of shale. However, the vertical erosion rate within the sandstone was higher than that within the shale, due to direct relationship between slope gradient and vertical erosion rate in the Aka-kuzure landslide.

  15. Preparation of a novel carbon-based solid acid from cassava stillage residue and its use for the esterification of free fatty acids in waste cooking oil.

    PubMed

    Wang, Lingtao; Dong, Xiuqin; Jiang, Haoxi; Li, Guiming; Zhang, Minhua

    2014-04-01

    A novel carbon-based solid acid catalyst was prepared by the sulfonation of incompletely carbonized cassava stillage residue (CSR) with concentrated sulfuric acid, and employed to catalyze the esterification of methanol and free fatty acids (FFAs) in waste cooking oil (WCO). The effects of the carbonization and the sulfonation temperatures on the pore structure, acid density and catalytic activity of the CSR-derived catalysts were systematically investigated. Low temperature carbonization and high temperature sulfonation can cause the collapse of the carbon framework, while high temperature carbonization is not conducive to the attachment of SO3H groups on the surface. The catalyst showed high catalytic activity for esterification, and the acid value for WCO is reduced to below 2mg KOH/g after reaction. The activity of catalyst can be well maintained after five cycles. CSR can be considered a promising raw material for the production of a new eco-friendly solid acid catalyst. PMID:24661813

  16. Enhancing the performance of lead-acid batteries with carbon - In pursuit of an understanding

    NASA Astrophysics Data System (ADS)

    Moseley, Patrick T.; Rand, David A. J.; Peters, Ken

    2015-11-01

    The inherently poor dynamic charge-acceptance of the lead-acid battery can be greatly improved by the incorporation of additional carbon to the negative plate. An analysis is undertaken of the various ways by which the carbon may be introduced, and of the proposed mechanisms whereby its presence proves to be beneficial. It is intended that such an investigation should provide a guide to the selection of the optimum carbon inventory.

  17. Reconciling Empirical Carbonate Clumped Isotope Calibrations: A Comparison of Calcite Precipitation and Acid Digestion Methods

    NASA Astrophysics Data System (ADS)

    Kelson, J.; Huntington, K. W.; Schauer, A. J.; Saenger, C.; Lechler, A. R.

    2015-12-01

    An accurate empirical calibration is necessary to confidently apply the carbonate clumped isotope (Δ47) thermometer. Previous synthetic carbonate calibrations disagree in temperature sensitivity, with one group of calibrations displaying a shallow Δ47-temperature slope (e.g., Dennis & Schrag, GCA, 2010), and the other a steep slope (e.g., Zaarur et al., EPSL, 2013). These calibrations differ in both the method of mineral precipitation and the temperature of the phosphoric acid used to digest carbonates for analysis, making it difficult to isolate the cause of the discrepancy. Here, we precipitate synthetic carbonates at temperatures of 6-80ºC using 4 different precipitation methods, and analyze the samples using both 90 and 25°C acid digestion. Precipitation experiments varied the use of salts (NaHCO3 and CaCl2) vs. dissolved CaCO3 as a starting solution, the use of carbonic anhydrase to promote isotopic equilibrium among dissolved inorganic carbon species in solution, and the method by which CO2 degasses to force carbonate precipitation. Carbonates precipitated by using salts and allowing CO2 to passively degas produce a shallow calibration slope that we hypothesize to approach isotopic equilibrium. Precipitation methods that bubble CO2 into solution then degas that CO2 (either passively or actively by bubbling N2) produce carbonates with consistently lower Δ47 and higher δ18O values for a given growth temperature. We infer that these carbonates grew in disequilibrium during rapid CO2 degassing. Varying acid digestion temperature does not change the results; acid fractionation factor is not correlated with grain size, Δ47, or d47 values. No precipitation method produces a steep calibration slope. Our large sample set of >60 carbonates lend confidence to a shallow slope calibration, and inform interpretations of Δ47 and δ18O values of natural carbonates that grow under conditions of isotopic disequilibrium.

  18. Predicting the Sorption of Aromatic Acids to Noncarbonized and Carbonized Sorbents.

    PubMed

    Sigmund, Gabriel; Sun, Huichao; Hofmann, Thilo; Kah, Melanie

    2016-04-01

    Approaches based on the octanol-water partition coefficient are commonly used to describe sorption of neutral organic compounds in environmental systems, but they are not suitable for organic acids, which can dissociate to form anions. We here investigate the applicability of an alternative approach based on the pH-dependent distribution ratio (DOW) to describe sorption of aromatic acids to sorbents representing different degrees of carbonization. Sorption isotherms for four structurally similar acids ((2,4-dichlorophenoxy)acetic acid (2,4-D), 4-chloro-2-15 methylphenoxy)acetic acid (MCPA), 4-(2,4-dichlorophenoxy)butanoic16 acid (2,4-DB), and 5-chloro-2-(2,4-dichlorophenoxy)phenol (triclosan)) were measured for 15 sorbents: fresh and carbonized wood shavings, pig manure, sewage sludge, carbon nanotubes, and activated carbon. Dissociation greatly affected the sorption of all acids. Sorption coefficients measured in the high pH range indicated that sorption of the anions ranged over several orders of magnitude and should not be neglected. Sorption trends for all sorbates and carbonized sorbents could be very well described by a single regression equation that included DOW of the sorbate and the specific surface area of the sorbent (R(2) > 0.89). PMID:26949216

  19. Carbonic Acid as a Reserve of Carbon Dioxide on Icy Moons: The Formation of Carbon Dioxide (CO2) in a Polar Environment

    NASA Astrophysics Data System (ADS)

    Jones, Brant M.; Kaiser, Ralf I.; Strazzulla, Giovanni

    2014-06-01

    Carbon dioxide (CO2) has been detected on the surface of several icy moons of Jupiter and Saturn via observation of the ν3 band with the Near-Infrared Mapping Spectrometer on board the Galileo spacecraft and the Visible-Infrared Mapping Spectrometer on board the Cassini spacecraft. Interestingly, the CO2 band for several of these moons exhibits a blueshift along with a broader profile than that seen in laboratory studies and other astrophysical environments. As such, numerous attempts have been made in order to clarify this abnormal behavior; however, it currently lacks an acceptable physical or chemical explanation. We present a rather surprising result pertaining to the synthesis of carbon dioxide in a polar environment. Here, carbonic acid was synthesized in a water (H2O)-carbon dioxide (CO2) (1:5) ice mixture exposed to ionizing radiation in the form of 5 keV electrons. The irradiated ice mixture was then annealed, producing pure carbonic acid which was then subsequently irradiated, recycling water and carbon dioxide. However, the observed carbon dioxide ν3 band matches almost exactly with that observed on Callisto; subsequent temperature program desorption studies reveal that carbon dioxide synthesized under these conditions remains in solid form until 160 K, i.e., the sublimation temperature of water. Consequently, our results suggest that carbon dioxide on Callisto as well as other icy moons is indeed complexed with water rationalizing the shift in peak frequency, broad profile, and the solid state existence on these relatively warm moons.

  20. Inhibition of nitrobenzene adsorption by water cluster formation at acidic oxygen functional groups on activated carbon.

    PubMed

    Kato, Yuichi; Machida, Motoi; Tatsumoto, Hideki

    2008-06-15

    The inhibition effect of nitrobenzene adsorption by water clusters formed at the acidic groups on activated carbon was examined in aqueous and n-hexane solution. The activated carbon was oxidized with nitric acid to introduce CO complexes and then outgassed in helium flow at 1273 K to remove them completely without changing the structural properties of the carbon as a reference adsorbent. The amounts of acidic functional groups were determined by applying Boehm titration. A relative humidity of 95% was used to adsorb water onto the carbon surface. Strong adsorption of water onto the oxidized carbon can be observed by thermogravimetric analysis. The adsorption kinetic rate was estimated to be controlled by diffusion from the kinetic analysis. Significant decline in both capacity and kinetic rate for nitrobenzene adsorption onto the oxidized carbon was also observed in n-hexane solution by preadsorption of water to the carbon surface, whereas it was not detected for the outgassed carbons. These results might reveal that water molecules forming clusters at the CO complexes inhibited the entrance of nitrobenzene into the interparticles of the carbon. PMID:18440013

  1. Stable carbon isotopic compositions of low-molecular-weight dicarboxylic acids, oxocarboxylic acids, α-dicarbonyls, and fatty acids: implications for atmospheric processing of organic aerosols

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Kawamura, K.; Cao, F.; Lee, M.

    2015-12-01

    Stable carbon isotopic compositions (δ13C) were measured for 23 individual organic species including 9 dicarboxylic acids, 7 oxocarboxylic acids, 1 tricarboxylic acid, 2 α-dicarbonyls and 4 fatty acids in the aerosols from Gosan background site in East Asia. δ13C of particle-phase glyoxal and methylglyoxal are significantly higher than those previously reported for isoprene and other precursors, associated with isotope fractionation during atmospheric oxidation. 13C is consistently more enriched for oxalic acid (C2), glyoxylic acid, pyruvic acid, glyoxal and methylglyoxal compared to other organic compounds identified, which can be explained by the kinetic isotope effects during aqueous-phase processing and the subsequent gas-particle partitioning after clouds or wet aerosols evaporation δ13C of C2 is positively correlated with C2 and organic carbon ratio, indicating that a photochemical production of C2 is more pronounced than its degradation process during long-range transport. The 13C results also suggest that aqueous-phase oxidation of glyoxal and methylglyoxal is major formation process of oxalic acid production via the major intermediates glyoxylic acid and pyruvic acid. This study provides evidence that organic aerosols are intensively photo-chemically aged in this region.

  2. PERFORMANCE AND MODELING OF A HOT POTASSIUM CARBONATE ACID GAS REMOVAL SYSTEM IN TREATING COAL GAS

    EPA Science Inventory

    The report discusses the performance and modeling of a hot potassium carbonate (K2CO3) acid gas removal system (AGRS) in treating coal gas. Aqueous solutions of K2CO3, with and without amine additive, were used as the acid gas removal solvent in the Coal Gasification/Gas Cleaning...

  3. Amino Acid Synthesis in a Supercritical Carbon Dioxide - Water System

    PubMed Central

    Fujioka, Kouki; Futamura, Yasuhiro; Shiohara, Tomoo; Hoshino, Akiyoshi; Kanaya, Fumihide; Manome, Yoshinobu; Yamamoto, Kenji

    2009-01-01

    Mars is a CO2-abundant planet, whereas early Earth is thought to be also CO2-abundant. In addition, water was also discovered on Mars in 2008. From the facts and theory, we assumed that soda fountains were present on both planets, and this affected amino acid synthesis. Here, using a supercritical CO2/liquid H2O (10:1) system which mimicked crust soda fountains, we demonstrate production of amino acids from hydroxylamine (nitrogen source) and keto acids (oxylic acid sources). In this research, several amino acids were detected with an amino acid analyzer. Moreover, alanine polymers were detected with LC-MS. Our research lights up a new pathway in the study of life’s origin. PMID:19582225

  4. Hexavalent chromium [Cr(VI)] removal by acid modified waste activated carbons.

    PubMed

    Ghosh, Pranab Kumar

    2009-11-15

    Fresh activated carbon (AC) and waste activated carbon (WAC) were pretreated by heating with mineral acids (sulfuric acid and nitric acid) at high temperature to prepare several grades of adsorbents to evaluate their performance on Cr(VI) removal from aqueous phase. Effects of temperature, agitation speed and pH were tested, and optimum conditions were evaluated. Kinetic study was performed under optimum conditions with several grades of modified adsorbents to know the rates of adsorption. Batch adsorption equilibrium data followed both, Freuindlich and Langmuir isotherms. Maximum adsorption capacity (q(max)) of the selected adsorbents treated with sulfuric acid (MWAC 1) and nitric acid (MWAC 2), calculated from Langmuir isotherm are 7.485 and 10.929 mg/g, respectively. Nitric acid treated adsorbent (MWAC 2) was used for column study to determine the constants of bed depth service time (BDST) model for adsorption column design. PMID:19553008

  5. Surface modification of activated carbon for enhanced adsorption of perfluoroalkyl acids from aqueous solutions.

    PubMed

    Zhi, Yue; Liu, Jinxia

    2016-02-01

    The objective of the research was to examine the effect of increasing carbon surface basicity on uptake of perfluorooctane sulfonic (PFOS) and carboxylic acids (PFOA) by activated carbon. Granular activated carbons made from coal, coconut shell, wood, and phenolic-polymer-based activated carbon fibers were modified through high-temperature and ammonia gas treatments to facilitate systematical evaluation of the impact of basicity of different origins. Comparison of adsorption isotherms and adsorption distribution coefficients showed that the ammonia gas treatment was more effective than the high-temperature treatment in enhancing surface basicity. The resultant higher point of zero charges and total basicity (measured by total HCl uptake) correlated with improved adsorption affinity for PFOS and PFOA. The effectiveness of surface modification to enhance adsorption varied with carbon raw material. Wood-based carbons and activated carbon fibers showed enhancement by one to three orders of magnitudes while other materials could experience reduction in adsorption towards either PFOS or PFOA. PMID:26469934

  6. [Some considerations about the use of carbon sources in jasmonic acid production.].

    PubMed

    Almeida González, G; Klibansky Delgado, M; Altuna Seijas, B; Eng Sánchez, F; Legrá Mora, S; Armenteros Galarraga, S

    1999-09-01

    The effect of different carbon sources as sucrose, fructose, glucose and molasses were studied in relation to jasmonic acid production. The best results were obtained with a simple medium made up by final molasses, potassium nitrate and acid potassium phosphate, without the addition of other salts like Fe, Zn, Cu, Mo, etc. This alternative guaranteed a 100% increase in jasmonic acid production, compared to pattern medium, since a concentration of 2.08 g/l was obtained. PMID:18473562

  7. Hasty retreat of glaciers in northern Patagonia

    NASA Astrophysics Data System (ADS)

    Paul, Frank; Mölg, Nico

    2014-05-01

    decline (area and thickness loss). Some glaciers retreated more than 3 km over this time period or even disappeared completely. Typically, these glaciers lost contact to the accumulation areas of tributaries and melted away as dead ice. Furthermore, numerous proglacial lakes formed or expanded rapidly, increasing the local hazard potential. On the other hand, some glaciers located on or near to (still active) volcanoes have also slightly advanced over the same time period. Observed trends in temperature (decreasing) are in contrast to the observed strong glacier shrinkage, indicating that also other factors must play a role.

  8. Highly ordered three dimensional macroporous carbon spheres and their acid catalytic properties

    NASA Astrophysics Data System (ADS)

    Huang, Hui; Zhang, Jianming; Zhang, Yuxiao; Lian, Suoyuan; Liu, Yang

    2013-10-01

    Highly ordered three dimensional macroporous carbon spheres bearing sulfonic acid groups (MPCS-SO3H) were prepared by incomplete carbonization of glucose in silica crystal bead template, followed by sulfonation and removal of the template. The composition and porous structure of the obtained carbon spheres were investigated by physical adsorption of nitrogen, scanning electron microscopy, energy dispersive X-ray spectroscopy, and transmission electron microscopy techniques. While the Fourier-transform infrared spectroscopy was used to characterize the functional groups on the surface of carbon spheres. The catalytic properties of the MPCS-SO3H were evaluated by esterification of ethanol with acetic acid, indicating that MPCS-SO3H possess remarkable catalytic performance (high stability and acid catalytic ability) for the esterification.

  9. Photochemical functionalization of diamond films using a short carbon chain acid

    NASA Astrophysics Data System (ADS)

    Wang, Chun; Huang, Nan; Zhuang, Hao; Yang, Bing; Zhai, Zhaofeng; Jiang, Xin

    2016-02-01

    Diamond is recognized as a promising semiconductor material for biological applications, because of its high chemical stability and biocompatibility. Here, we report an acid with only three carbon chain, acrylic acid (AA), for the functionalization of H-terminated diamond film via photochemical method. The successfully modified surfaces were characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy and contact angle analyzer. Our functionalization approach was proven to be simple and facile, which shows a new potential opportunity for the photochemical modification of diamond surface with short carbon chain acid.

  10. X-ray microtomography of hydrochloric acid propagation in carbonate rocks.

    PubMed

    Machado, A C; Oliveira, T J L; Cruz, F B; Lopes, R T; Lima, I

    2015-02-01

    Acid treatments are used in the oil and gas industry, to increase the permeability of the carbonate reservoirs by creating preferential channels, called wormholes. Channels formation is strongly influenced by acid type and injection rate. The aim of this study is to evaluate some characteristics of the microporous system of carbonate rocks, before and after acidizing. For that purpose X-ray high-resolution microtomography was used. The results show that this technique can be used as a reliable method to analyze microstructural characteristics of the wormholes. PMID:25485884

  11. Porous structure and surface chemistry of phosphoric acid activated carbon from corncob

    NASA Astrophysics Data System (ADS)

    Sych, N. V.; Trofymenko, S. I.; Poddubnaya, O. I.; Tsyba, M. M.; Sapsay, V. I.; Klymchuk, D. O.; Puziy, A. M.

    2012-11-01

    Active carbons have been prepared from corncob using chemical activation with phosphoric acid at 400 °C using varied ratio of impregnation (RI). Porous structure of carbons was characterized by nitrogen adsorption and scanning electron microscopy. Surface chemistry was studied by IR and potentiometric titration method. It has been shown that porosity development was peaked at RI = 1.0 (SBET = 2081 m2/g, Vtot = 1.1 cm3/g), while maximum amount of acid surface groups was observed at RI = 1.25. Acid surface groups of phosphoric acid activated carbons from corncob includes phosphate and strongly acidic carboxylic (pK = 2.0-2.6), weakly acidic carboxylic (pK = 4.7-5.0), enol/lactone (pK = 6.7-7.4; 8.8-9.4) and phenol (pK = 10.1-10.7). Corncob derived carbons showed high adsorption capacity to copper, especially at low pH. Maximum adsorption of methylene blue and iodine was observed for carbon with most developed porosity (RI = 1.0).

  12. Dissimilation of Carbon Monoxide to Acetic Acid by Glucose-Limited Cultures of Clostridium thermoaceticum

    PubMed Central

    Martin, Douglas R.; Misra, Arun; Drake, Harold L.

    1985-01-01

    Clostridium thermoaceticum was cultivated in glucose-limited media, and the dissimilation of CO to acetic acid was evaluated. We found that cultures catalyzed the rapid dissimilation of CO to acetic acid and CO2, with the stoichiometry obtained for conversion approximating that predicted from the following reaction: 4CO + 2H2O → CH3CO2H + 2CO2. Growing cultures formed approximately 50 mmol (3 g) of CO-derived acetic acid per liter of culture, with the rate of maximal consumption approximating 9.1 mmol of CO consumed/h per liter of culture. In contrast, resting cells were found not to dissimilate CO to acetic acid. 14CO was incorporated, with equal distribution between the carboxyl and methyl carbons of acetic acid when the initial cultivation gas phase was 100% CO, whereas 14CO2 preferentially entered the carboxyl carbon when the initial gas phase was 100% CO2. Significantly, in the presence of saturating levels of CO, 14CO2 preferentially entered the methyl carbon, whereas saturating levels of CO2 yielded 14CO-derived labeling predominantly in the carboxyl carbon. These findings are discussed in relation to the path of carbon flow to acetic acid. PMID:16346807

  13. A complex deglacial retreat history of the Anvers Island Trough paleo-ice stream

    NASA Astrophysics Data System (ADS)

    Shevenell, A.; Ishman, S. E.; Domack, E. W.; Leventer, A.; Rosenheim, B. E.; Vadman, K. J.

    2015-12-01

    Marine-terminating ice regulates the mass balance and stability of Antarctica's ice sheets and, ultimately, global sea level. However, predictions of future ice sheet response to climate change are limited by short observational time-series and the complexity of associated forcings and feedbacks. Here, we present new chronologic and multiproxy data from 7 marine sediment records from the outer to inner shelf down the axis of the Anvers Island Trough and into Palmer Deep that better constrain the timing and rate of ice retreat and improve understanding of the mechanisms driving deglaciation of this hypothesized paleo-ice stream. The retreat chronology is based on 16 CaCO3 (foraminifer and mollusk) and 45 ramped pyrolysis (acid-insoluble organic matter) AMS 14C dates. Radiocarbon dates from the laminated diatom ooze and mud facies immediately above the glacial diamicton indicate that deglaciation of the mid-Anvers Island Trough post-dated the Palmer Deep deglaciation by ~2000 uncorrected 14C years and that collapse of the mid-shelf system was rapid, if not instantaneous. The laminated facies, present throughout the suite of cores, is consistent with the calving bay reentrant model for deglaciation. However, this facies is limited (~15 couplets) on the mid-shelf and expanded (~127 couplets) on the inner-shelf, suggesting regional differences in calving bay duration. Planktic and benthic foraminifer isotopes, together with foraminifer and diatom assemblages, and biogeochemical data provide evidence for the presence of warmer nutrient-rich modified Circumpolar Deep Water throughout the Anvers Island Trough during deglaciation. The observed retreat complexity may relate to a hypothesized mid-shelf ice-dome system and requires additional geological and geophysical data to understand ice retreat patterns south and west of Palmer Deep. Such data will provide important new constraints for ice sheet models.

  14. Endodontic retreatment. Aspects of decision making and clinical outcome.

    PubMed

    Kvist, T

    2001-01-01

    Epidemiological surveys have reported that 25%-35% of root filled teeth are associated with periapical radiolucencies. Descriptive studies have demonstrated that clinicians' decision making regarding such teeth are subject to substantial variation. A coherent model to explain the observed variation has not been produced. In the present thesis a "Praxis Concept theory" was proposed. The theory suggests that dentists perceive periapical lesions of varying sizes as different stages on a continuous health scale. Interindividual variations can then be regarded as the result of the choice of different cut-off points on the continuum for prescribing retreatment. In the present study experiments among novice and expert decision makers gave evidence in favour of the theory. Data also suggested that the choice of retreatment criterion is affected by values, costs of retreatment and technical quality of original treatment. From a prescriptive point of view, the presence of a persistent periapical radiolucency has often been used as a criterion of endodontic "failure" and as an indication for endodontic retreatment. As an alternative decision strategy, the use of decision analysis has been proposed. Logical display of decision alternatives, values of probabilities, utility values (U-values) of the different outcomes and calculation of optimal decision strategy are features of this theory. The implementation of this approach is impeded by the uncertainty of outcome probabilities and lack of investigations concerning U-values. U-values of two periapical health states in root filled teeth (with and without a periapical lesion respectively) were investigated in a group of 82 dental students and among 16 Swedish endodontists. Two methods were used to elicit U-values: Standard gamble and Visual Analogue Scale. Large interindividual variation for both health states were recorded. The difference in U-values between the two health states was found to be statistically significant

  15. Adsorption of perfluoroalkyl acids by carbonaceous adsorbents: Effect of carbon surface chemistry.

    PubMed

    Zhi, Yue; Liu, Jinxia

    2015-07-01

    Adsorption by carbonaceous sorbents is among the most feasible processes to remove perfluorooctane sulfonic (PFOS) and carboxylic acids (PFOA) from drinking and ground waters. However, carbon surface chemistry, which has long been recognized essential for dictating performance of such sorbents, has never been considered for PFOS and PFOA adsorption. Thus, the role of surface chemistry was systematically investigated using sorbents with a wide range in precursor material, pore structure, and surface chemistry. Sorbent surface chemistry overwhelmed physical properties in controlling the extent of uptake. The adsorption affinity was positively correlated carbon surface basicity, suggesting that high acid neutralizing or anion exchange capacity was critical for substantial uptake of PFOS and PFOA. Carbon polarity or hydrophobicity had insignificant impact on the extent of adsorption. Synthetic polymer-based Ambersorb and activated carbon fibers were more effective than activated carbon made of natural materials in removing PFOS and PFOA from aqueous solutions. PMID:25827692

  16. Metabolic carbon fluxes and biosynthesis of polyhydroxyalkanoates in Ralstonia eutropha on short chain fatty acids.

    PubMed

    Yu, Jian; Si, Yingtao

    2004-01-01

    Short chain fatty acids such as acetic, propionic, and butyric acids can be synthesized into polyhydroxyalkanoates (PHAs) by Ralstonia eutropha. Metabolic carbon fluxes of the acids in living cells have significant effect on the yield, composition, and thermomechanical properties of PHA bioplastics. Based on the general knowledge of central metabolism pathways and the unusual metabolic pathways in R. eutropha, a metabolic network of 41 bioreactions is constructed to analyze the carbon fluxes on utilization of the short chain fatty acids. In fed-batch cultures with constant feeding of acid media, carbon metabolism and distribution in R. eutropha were measured involving CO2, PHA biopolymers, and residual cell mass. As the cells underwent unsteady state metabolism and PHA biosynthesis under nitrogen-limited conditions, accumulative carbon balance was applied for pseudo-steady-state analysis of the metabolic carbon fluxes. Cofactor NADP/NADPH balanced between PHA synthesis and the C3/C4 pathway provided an independent constraint for solution of the underdetermined metabolic network. A major portion of propionyl-CoA was directed to pyruvate via the 2-methylcitrate cycle and further decarboxylated to acetyl-CoA. Only a small amount of propionate carbon (<15% carbon) was directly condensed with acetyl-CoA for 3-hydroxyvalerate. The ratio of glyoxylate shunt to TCA cycle varies from 0 to 0.25, depending on the intracellular acetyl-CoA level and acetic acid in the medium. Malate is the node of the C3/C4 pathway and TCA cycle and its decarboxylation to dehydrogenation ranges from 0.33 to 1.28 in response to the demands on NADPH and oxaloacetate for short chain fatty acids utilization. PMID:15296425

  17. Effects of simulated acid precipitation on decomposition and leaching of organic carbon in forest soils

    SciTech Connect

    Chang, F.H.; Alexander, M.

    1984-09-01

    Soil samples from three watersheds of New York State were treated with simulated rain at pH 3.5, 4.1, and 5.6 daily for 14 d, at 12 3-d intervals in three separate tests, or at 22 7-d intervals. Except for one system of treating the three forest soils, simulated acid rain reduced the amount of organic matter leached from samples of soil from which more than 0.05% of the organic carbon was leached during the exposure period. In the soil samples representing the exceptions, acid rain enhanced the leaching of organic matter. Samples from the organic layer of the treated samples of acid soil were taken at two equal depths, and the rates of organic matter decomposition in the two layers were studied. As compared with simulated rain at pH 5.6, simulated acid rain reduced the decomposition of organic matter in the three soils at both depths in three of the five tests and at both depths of two of the soils in the fourth test. In some instances, organic matter decomposition was enhanced by the simulated acid rain. Except for the sample of soil at the highest initial pH, carbon mineralization was inhibited in soils and treatments in which simulated acid rain reduced the amount of organic carbon leached, and it was stimulated in soils and treatments in which the quantity of organic carbon leached was increased by the simulated acid rain. 12 references, 3 figures, 8 tables.

  18. Fumaric acid: an overlooked form of fixed carbon in Arabidopsis and other plant species

    SciTech Connect

    Chia, D.W.; Yoder, T.J.; Reiter, W.D.; Gibson, S.I.

    2000-10-01

    Photoassimilates are used by plants for production of energy, as carbon skeletons and in transport of fixed carbon between different plant organs. Many studies have been devoted to characterizing the factors that. regulate photoassimilate concentrations in different plant species. Most studies examining photoassimilate concentrations in C{sub 3} plants have focused on analyzing starch and soluble sugars. However, work presented here demonstrates that a number of C{sub 3} plants, including the popular model organism Arabidopsis thaliana (L.) Heynh., and agriculturally important plants, such as soybean [Glycine ma (L.) Merr.], contain significant quantities of furnaric acid. In fact, furnaric acid can accumulate to levels of several mg per g fresh weight in A-abidopsis leaves, often exceeding starch and soluble sugar levels. Furnaric acid is a component of the tricarboxylic acid cycle and, like starch and soluble sugars, can be metabolized to yield energy and carbon skeletons for production of other compounds. Fumaric acid concentrations increase with plant age and light intensity in Arabidopsis leaves. Arabidopsis phloem exudates contain significant quantities of fumaric acid, raising the possibility that fumaric acid may function in carbon transport.

  19. Inhibition Effect of Dodecylamine on Carbon Steel Corrosion in Hydrochloric Acid Solution

    NASA Astrophysics Data System (ADS)

    Chen, Zhenyu; Huang, Ling; Qiu, Yubing; Guo, Xingpeng

    2012-12-01

    Dodecylamine spontaneously adsorbs on carbon steel via its polar group (-NH2) in hydrochloric acid solution. Furthermore, it forms a monolayer film on carbon steel surface. The inhibition mechanism of dodecylamine for carbon steel is geometric blocking effect. The adsorption of dodecylamine on carbon steel surface follows Arrhenius equation. The adsorption slightly increases activated energy, but greatly reduces pre-exponential factor value. Atomic force microscopy force curves indicate that at the area without adsorbed dodecylamine, no obvious adhere force occurs. At the area with adsorbed dodecylamine, however, an average 1.3 nN adhere force is observed.

  20. Field evaluation of gelled acid for carbonate formations

    SciTech Connect

    Church, D.C.; Quisenberry, J.L.; Fox, K.B.

    1981-01-01

    A new gelled acid was evaluated in W. Texas, S.E. New Mexico, and Oklahoma. The evaluation determined how successful a gelled acid, prepared from xanthan polymer, would be in the following formations: Ellenburger, Blinebry, San Andres, Clearfork, Canyon Lime, Strawn Lime, Grayburg, Devonian, Drinkard Dolomite, Viola and Chester. Treatment depths vary from 4000 to 22,000 ft. Treatment temperatures vary from 70 to 310 F. Treatments were performed on both oil and gas wells. The age of the wells stimulated varies from new to 30 yr old. The concentration of gelled acid remained constant at 15% HCl. The concentration of gelling agent remained constant at 60 lb/1000 gal. The size of the treatments varied from 5000 to 80,000 gal of gelled acid. More than 20 treatments are summarized. Production figures for the well treated are summarized. Production figures for the wells treated are discussed, as well as pertinent related information.

  1. Influence of Sodium Carbonate on Decomposition of Formic Acid by Discharge inside Bubble in Water

    NASA Astrophysics Data System (ADS)

    Iwabuchi, Masashi; Takahashi, Katsuyuki; Takaki, Koichi; Satta, Naoya

    2015-09-01

    An influence of sodium carbonate on decomposition of formic acid by discharge inside bubble in water was investigated. Oxygen or argon gases were injected into the water through a vertically positioned glass tube, in which the high-voltage wire electrode was placed to generate plasmas at low applied voltage. The concentration of formic acid was determined by ion chromatography. In the case of addition of sodium carbonate, the pH value increased with decomposition of the formic acid. In the case of oxygen injection, the increase of pH value contributed to improve an efficiency of the formic acid decomposition because the reaction rate of ozone and formic acid increased with increasing pH value. In the case of argon injection, the decomposition rate was not affected by the pH value owing to the high rate constants for loss of hydroxyl radicals.

  2. Catalytic Decarboxylation of Fatty Acids to Aviation Fuels over Nickel Supported on Activated Carbon

    NASA Astrophysics Data System (ADS)

    Wu, Jianghua; Shi, Juanjuan; Fu, Jie; Leidl, Jamie A.; Hou, Zhaoyin; Lu, Xiuyang

    2016-06-01

    Decarboxylation of fatty acids over non-noble metal catalysts without added hydrogen was studied. Ni/C catalysts were prepared and exhibited excellent activity and maintenance for decarboxylation. Thereafter, the effects of nickel loading, catalyst loading, temperature, and carbon number on the decarboxylation of fatty acids were investigated. The results indicate that the products of cracking increased with high nickel loading or catalyst loading. Temperature significantly impacted the conversion of stearic acid but did not influence the selectivity. The fatty acids with large carbon numbers tend to be cracked in this reaction system. Stearic acid can be completely converted at 370 °C for 5 h, and the selectivity to heptadecane was around 80%.

  3. Catalytic Decarboxylation of Fatty Acids to Aviation Fuels over Nickel Supported on Activated Carbon

    PubMed Central

    Wu, Jianghua; Shi, Juanjuan; Fu, Jie; Leidl, Jamie A.; Hou, Zhaoyin; Lu, Xiuyang

    2016-01-01

    Decarboxylation of fatty acids over non-noble metal catalysts without added hydrogen was studied. Ni/C catalysts were prepared and exhibited excellent activity and maintenance for decarboxylation. Thereafter, the effects of nickel loading, catalyst loading, temperature, and carbon number on the decarboxylation of fatty acids were investigated. The results indicate that the products of cracking increased with high nickel loading or catalyst loading. Temperature significantly impacted the conversion of stearic acid but did not influence the selectivity. The fatty acids with large carbon numbers tend to be cracked in this reaction system. Stearic acid can be completely converted at 370 °C for 5 h, and the selectivity to heptadecane was around 80%. PMID:27292280

  4. Catalytic Decarboxylation of Fatty Acids to Aviation Fuels over Nickel Supported on Activated Carbon.

    PubMed

    Wu, Jianghua; Shi, Juanjuan; Fu, Jie; Leidl, Jamie A; Hou, Zhaoyin; Lu, Xiuyang

    2016-01-01

    Decarboxylation of fatty acids over non-noble metal catalysts without added hydrogen was studied. Ni/C catalysts were prepared and exhibited excellent activity and maintenance for decarboxylation. Thereafter, the effects of nickel loading, catalyst loading, temperature, and carbon number on the decarboxylation of fatty acids were investigated. The results indicate that the products of cracking increased with high nickel loading or catalyst loading. Temperature significantly impacted the conversion of stearic acid but did not influence the selectivity. The fatty acids with large carbon numbers tend to be cracked in this reaction system. Stearic acid can be completely converted at 370 °C for 5 h, and the selectivity to heptadecane was around 80%. PMID:27292280

  5. In vitro toxicity of carbon nanotubes, nano-graphite and carbon black, similar impacts of acid functionalization.

    PubMed

    Figarol, Agathe; Pourchez, Jérémie; Boudard, Delphine; Forest, Valérie; Akono, Céline; Tulliani, Jean-Marc; Lecompte, Jean-Pierre; Cottier, Michèle; Bernache-Assollant, Didier; Grosseau, Philippe

    2015-12-25

    Carbon nanotubes (CNT) and nano-graphite (NG) are graphene-based nanomaterials which share exceptional physicochemical properties, but whose health impacts are unfortunately still not well understood. On the other hand, carbon black (CB) is a conventional and widely studied material. The comparison of these three carbon-based nanomaterials is thus of great interest to improve our understanding of their toxicity. An acid functionalization was carried out on CNT, NG and CB so that, after a thorough characterization, their impacts on RAW 264.7 macrophages could be compared for a similar surface chemistry (15 to 120 μg·mL(-1) nanomaterials, 90-min to 24-h contact). Functionalized nanomaterials triggered a weak cytotoxicity similar to the pristine nanomaterials. Acid functionalization increased the pro-inflammatory response except for CB which did not trigger any TNF-α production before or after functionalization, and seemed to strongly decrease the oxidative stress. The toxicological impact of acid functionalization appeared thus to follow a similar trend whatever the carbon-based nanomaterial. At equivalent dose expressed in surface and equivalent surface chemistry, the toxicological responses from murine macrophages to NG were higher than for CNT and CB. It seemed to correspond to the hypothesis of a platelet and fiber paradigm. PMID:26381085

  6. Chemical and biological consequences of using carbon dioxide versus acid additions in ocean acidification experiments

    USGS Publications Warehouse

    Yates, Kimberly K.; DuFore, Christopher M.; Robbins, Lisa L.

    2013-01-01

    Use of different approaches for manipulating seawater chemistry during ocean acidification experiments has confounded comparison of results from various experimental studies. Some of these discrepancies have been attributed to whether addition of acid (such as hydrochloric acid, HCl) or carbon dioxide (CO2) gas has been used to adjust carbonate system parameters. Experimental simulations of carbonate system parameter scenarios for the years 1766, 2007, and 2100 were performed using the carbonate speciation program CO2SYS to demonstrate the variation in seawater chemistry that can result from use of these approaches. Results showed that carbonate system parameters were 3 percent and 8 percent lower than target values in closed-system acid additions, and 1 percent and 5 percent higher in closed-system CO2 additions for the 2007 and 2100 simulations, respectively. Open-system simulations showed that carbonate system parameters can deviate by up to 52 percent to 70 percent from target values in both acid addition and CO2 addition experiments. Results from simulations for the year 2100 were applied to empirically derived equations that relate biogenic calcification to carbonate system parameters for calcifying marine organisms including coccolithophores, corals, and foraminifera. Calculated calcification rates for coccolithophores, corals, and foraminifera differed from rates at target conditions by 0.5 percent to 2.5 percent in closed-system CO2 gas additions, from 0.8 percent to 15 percent in the closed-system acid additions, from 4.8 percent to 94 percent in open-system acid additions, and from 7 percent to 142 percent in open-system CO2 additions.

  7. Influence of acid functionalization on the cardiopulmonary toxicity of carbon nanotubes and carbon black particles in mice

    SciTech Connect

    Tong Haiyan McGee, John K.; Saxena, Rajiv K.; Kodavanti, Urmila P.; Devlin, Robert B.; Gilmour, M. Ian

    2009-09-15

    Engineered carbon nanotubes are being developed for a wide range of industrial and medical applications. Because of their unique properties, nanotubes can impose potentially toxic effects, particularly if they have been modified to express functionally reactive chemical groups on their surface. The present study was designed to evaluate whether acid functionalization (AF) enhanced the cardiopulmonary toxicity of single-walled carbon nanotubes (SWCNT) as well as control carbon black particles. Mice were exposed by oropharyngeal aspiration to 10 or 40 {mu}g of saline-suspended single-walled carbon nanotubes (SWCNTs), acid-functionalized SWCNTs (AF-SWCNTs), ultrafine carbon black (UFCB), AF-UFCB, or 2 {mu}g LPS. 24 hours later, pulmonary inflammatory responses and cardiac effects were assessed by bronchoalveolar lavage and isolated cardiac perfusion respectively, and compared to saline or LPS-instilled animals. Additional mice were assessed for histological changes in lung and heart. Instillation of 40 {mu}g of AF-SWCNTs, UFCB and AF-UFCB increased percentage of pulmonary neutrophils. No significant effects were observed at the lower particle concentration. Sporadic clumps of particles from each treatment group were observed in the small airways and interstitial areas of the lungs according to particle dose. Patches of cellular infiltration and edema in both the small airways and in the interstitium were also observed in the high dose group. Isolated perfused hearts from mice exposed to 40 {mu}g of AF-SWCNTs had significantly lower cardiac functional recovery, greater infarct size, and higher coronary flow rate than other particle-exposed animals and controls, and also exhibited signs of focal cardiac myofiber degeneration. No particles were detected in heart tissue under light microscopy. This study indicates that while acid functionalization increases the pulmonary toxicity of both UFCB and SWCNTs, this treatment caused cardiac effects only with the AF-carbon

  8. The Path of Carbon in Photosynthesis VIII. The Role of Malic Acid

    DOE R&D Accomplishments Database

    Bassham, James A.; Benson, Andrew A.; Calvin, Melvin

    1950-01-25

    Malonate has been found to inhibit the formation of malic acid during short periods of photosynthesis with radioactive carbon dioxide. This result, together with studies which show the photosynthetic cycle to be operating normally at the same time, indicates that malic acid is not an intermediate in photosynthesis but is probably closely related to some intermediate of the cycle. Absence of labeled succinic and fumaric acids in these experiments, in addition to the failure of malonate to inhibit photosynthesis, precludes the participation of these acids as intermediates in photosynthesis.

  9. Synthesis of sulfonated porous carbon nanospheres solid acid by a facile chemical activation route

    SciTech Connect

    Chang, Binbin Guo, Yanzhen; Yin, Hang; Zhang, Shouren; Yang, Baocheng

    2015-01-15

    Generally, porous carbon nanospheres materials are usually prepared via a template method, which is a multi-steps and high-cost strategy. Here, we reported a porous carbon nanosphere solid acid with high surface area and superior porosity, as well as uniform nanospheical morphology, which prepared by a facile chemical activation with ZnCl{sub 2} using resorcinol-formaldehyde (RF) resins spheres as precursor. The activation of RF resins spheres by ZnCl{sub 2} at 400 °C brought high surface area and large volume, and simultaneously retained numerous oxygen-containing and hydrogen-containing groups due to the relatively low processing temperature. The presence of these functional groups is favorable for the modification of –SO{sub 3}H groups by a followed sulfonation treating with sulphuric acid and organic sulfonic acid. The results of N{sub 2} adsorption–desorption and electron microscopy clearly showed the preservation of porous structure and nanospherical morphology. Infrared spectra certified the variation of surface functional groups after activation and the successful modification of –SO{sub 3}H groups after sulfonation. The acidities of catalysts were estimated by an indirect titration method and the modified amount of –SO{sub 3}H groups were examined by energy dispersive spectra. The results suggested sulfonated porous carbon nanospheres catalysts possessed high acidities and –SO{sub 3}H densities, which endowed their significantly catalytic activities for biodiesel production. Furthermore, their excellent stability and recycling property were also demonstrated by five consecutive cycles. - Graphical abstract: Sulfonated porous carbon nanospheres with high surface area and superior catalytic performance were prepared by a facile chemical activation route. - Highlights: • Porous carbon spheres solid acid prepared by a facile chemical activation. • It owns high surface area, superior porosity and uniform spherical morphology. • It possesses

  10. Monodispersed Hollow SO3H-Functionalized Carbon/Silica as Efficient Solid Acid Catalyst for Esterification of Oleic Acid.

    PubMed

    Wang, Yang; Wang, Ding; Tan, Minghui; Jiang, Bo; Zheng, Jingtang; Tsubaki, Noritatsu; Wu, Mingbo

    2015-12-01

    SO3H-functionalized monodispersed hollow carbon/silica spheres (HS/C-SO3H) with primary mesopores were prepared with polystyrene as a template and p-toluenesulfonic acid (TsOH) as a carbon precursor and -SO3H source simultaneously. The physical and chemical properties of HS/C-SO3H were characterized by N2 adsorption, TEM, SEM, XPS, XRD, Raman spectrum, NH3-TPD, element analysis and acid-base titration techniques. As a solid acid catalyst, HS/C-SO3H shows excellent performance in the esterification of oleic acid with methanol, which is a crucial reaction in biodiesel production. The well-defined hollow architecture and enhanced active sites accessibility of HS/C-SO3H guarantee the highest catalytic performance compared with the catalysts prepared by activation of TsOH deposited on the ordered mesoporous silicas SBA-15 and MCM-41. At the optimized conditions, high conversion (96.9%) was achieved and no distinct activity drop was observed after 5 recycles. This synthesis strategy will provide a highly effective solid acid catalyst for green chemical processes. PMID:26588826

  11. Ocean forcing of glacier retreat in the western Antarctic Peninsula

    NASA Astrophysics Data System (ADS)

    Cook, A. J.; Holland, P. R.; Meredith, M. P.; Murray, T.; Luckman, A.; Vaughan, D. G.

    2016-07-01

    In recent decades, hundreds of glaciers draining the Antarctic Peninsula (63° to 70°S) have undergone systematic and progressive change. These changes are widely attributed to rapid increases in regional surface air temperature, but it is now clear that this cannot be the sole driver. Here, we identify a strong correspondence between mid-depth ocean temperatures and glacier-front changes along the ~1000-kilometer western coastline. In the south, glaciers that terminate in warm Circumpolar Deep Water have undergone considerable retreat, whereas those in the far northwest, which terminate in cooler waters, have not. Furthermore, a mid-ocean warming since the 1990s in the south is coincident with widespread acceleration of glacier retreat. We conclude that changes in ocean-induced melting are the primary cause of retreat for glaciers in this region.

  12. Ocean forcing of glacier retreat in the western Antarctic Peninsula.

    PubMed

    Cook, A J; Holland, P R; Meredith, M P; Murray, T; Luckman, A; Vaughan, D G

    2016-07-15

    In recent decades, hundreds of glaciers draining the Antarctic Peninsula (63° to 70°S) have undergone systematic and progressive change. These changes are widely attributed to rapid increases in regional surface air temperature, but it is now clear that this cannot be the sole driver. Here, we identify a strong correspondence between mid-depth ocean temperatures and glacier-front changes along the ~1000-kilometer western coastline. In the south, glaciers that terminate in warm Circumpolar Deep Water have undergone considerable retreat, whereas those in the far northwest, which terminate in cooler waters, have not. Furthermore, a mid-ocean warming since the 1990s in the south is coincident with widespread acceleration of glacier retreat. We conclude that changes in ocean-induced melting are the primary cause of retreat for glaciers in this region. PMID:27418507

  13. Formation of Carbonic Acid in Impact of CO2 on Ice and Water.

    PubMed

    Hirshberg, Barak; Gerber, R Benny

    2016-08-01

    A new mode of formation is proposed for carbonic acid in the atmosphere. It involves impact of vibrationally excited gas-phase CO2 molecules on water or ice particles. This is a first mechanism that supports formation on ice as well as on liquid water surfaces. Results of ab initio molecular dynamics simulations are presented on collisions of CO2 with (H2O)n clusters (n = 1, 4, 8, 12). Efficient formation of carbonic acid is seen with product lifetimes exceeding 100 ps. The reaction is feasible even for collision of CO2 with a single water molecule but in a different mechanism than for larger clusters. For clusters, the transition state shows charge separation into H3O(+)···HCO3(-), which transforms into neutral carbonic acid as the product, hydrated by the remaining waters. Possible atmospheric implications of the results are discussed. PMID:27420400

  14. Carbon isotope composition of low molecular weight hydrocarbons and monocarboxylic acids from Murchison meteorite

    NASA Technical Reports Server (NTRS)

    Yuen, G.; Blair, N.; Des Marais, D. J.; Chang, S.

    1984-01-01

    Carbon isotopic compositions have been measured for individual hydrocarbons and monocarboxylic acids from the Murchison meteorite, a C2 carbonaceous chondrite which fell in Australia in 1969. With few exceptions, notably benzene, the volatile products are substantially isotopically heavier than their terrestrial counterparts, signifying their extraterrestrial origin. For both classes of compounds, the ratio of C-13 to C-12 decreases with increasing carbon number in a roughly parallel manner, and each carboxylic acid exhibits a higher isotopic ratio than the hydrocarbon containing the same number of carbon atoms. These trends are consistent with the kinetically controlled synthesis of higher homologues from lower ones. The results suggest the possibility that the production mechanisms for hydrocarbons and carboxylic acids may be similar, and impose constraints on the identity of the reactant species.

  15. Comparison of the amount of apical debris extrusion associated with different retreatment systems and supplementary file application during retreatment process

    PubMed Central

    Çiçek, Ersan; Koçak, Mustafa Murat; Koçak, Sibel; Sağlam, Baran Can

    2016-01-01

    Background: The type of instrument affects the amount of debris extruded. The aim of this study was to compare the effect of retreatment systems and supplementary file application on the amount of apical debris extrusion. Materials and Methods: Forty-eight extracted mandibular premolars with a single canal and similar length were selected. The root canals were prepared with the ProTaper Universal system with a torque-controlled engine. The root canals were dried and were obturated using Gutta-percha and sealer. The specimens were randomly divided into four equal groups according to the retreatment procedures (Group 1, Mtwo retreatment files; Group 2, Mtwo retreatment files + Mtwo rotary file #30 supplementary file; Group 3, ProTaper Universal retreatment (PTUR) files; and Group 4, PTUR files + ProTaper F3 supplementary file). The extruded debris during instrumentation were collected into preweighed Eppendorf tubes. The amount of apically extruded debris was calculated by subtracting the initial weight of the tube from the final weight. Three consecutive weights were obtained for each tube. Results: No statistically significant difference was found in the amount of apically extruded debris between Groups 1 and 3 (P = 0.590). A significant difference was observed between Groups 1 and 2 (P < 0.05), and between Groups 3 and 4 (P < 0.05). Conclusions: The use of supplementary file significantly increased the amount of apically extruded debris. PMID:27563185

  16. Study of the influence of carbon on the negative lead-acid battery electrodes

    NASA Astrophysics Data System (ADS)

    Bača, Petr; Micka, Karel; Křivík, Petr; Tonar, Karel; Tošer, Pavel

    Experiments were made with negative lead-acid battery electrodes doped with different concentrations of powdered carbon. It turned out that the rate of formation decreased with the rising concentration of carbon added into the active material. During accelerated cycling in the PSoC regime, the cycle life showed a maximum at a concentration of carbon near 1%, whereas at lower or higher concentrations the cycle life was profoundly lower. A marked increase of the active mass resistance with the cycle number was recorded at carbon concentrations above 2%. Orientation experiments showed that compression of the lead-acid laboratory cells caused an increase of the cycle life of the negative electrode in the studied regime.

  17. Conversion of carbon dioxide to resorcylic acid under ultrasonication by Kolbe-Schmitt reaction.

    PubMed

    Shanthi, B; Palanivelu, K

    2015-11-01

    The present work focuses on a new approach for the synthesis of β-resorcylic acid based on Kolbe-Schmitt reaction using carbon dioxide under ultrasonic and mild condition. The Kolbe-Schmitt reaction is a process for the synthesis of β-resorcylic acid (2,4-dihydroxybenzoic acid) from resorcinol in aqueous potassium hydroxide solution with gaseous CO2. The influences of carbonation time, flow rate of CO2 and the molar ratio of resorcinol/potassium hydroxide on the yield percentage of resorcylic acid were investigated. The study was assessed with the conventional thermal method (non ultrasonic method) for Kolbe-Schmitt reaction and it was observed that applying ultrasound to save more than 95% and 38.6% energy as shown by energy consumption calculations in bath type and horn type sonicator respectively. β-Resorcylic acid formed was characterized by (1)H NMR, (13)C NMR, DEPT NMR and FTIR spectroscopy. The amount of CO2 utilized in the reaction was evaluated from the yield percentage of β-resorcylic acid yield. The maximum yield of resorcylic acid of 30% and 65% was obtained at the resorcinol/potassium hydroxide ratio of 1:3, carbonation time of 150 min and the CO2 flow rate of 2L/min in bath type and horn type ultrasonicator, respectively. The applicability of the research work was examined in two different positional isomers of resorcinol under optimum conditions. PMID:26186845

  18. One-Pot synthesis of phosphorylated mesoporous carbon heterogeneous catalysts with tailored surface acidity

    SciTech Connect

    Fulvio, Pasquale F; Mahurin, Shannon Mark; Mayes, Richard T; Bauer, Christopher; Wang, Xiqing; Veith, Gabriel M; Dai, Sheng

    2012-01-01

    Soft-templated phosphorylated mesoporous carbons with homogeneous distributions of phosphate groups were prepared by a 'one-pot' synthesis method using mixtures of phosphoric acid with hydrochloric, or nitric acids in the presence of Pluronic F127 triblock copolymer. Adjusting the various ratios of phosphoric acid used in these mixtures resulted in carbons with distinct adsorption, structural and surface acidity properties. The pore size distributions (PSDs) from nitrogen adsorption at -196 C showed that mesoporous carbons exhibit specific surface areas as high as 551 m{sup 2}/g and mesopores as large as 13 nm. Both structural ordering of the mesopores and the final phosphate contents were strongly dependent on the ratios of H{sub 3}PO{sub 4} in the synthesis gels, as shown by transmission electron microscopy (TEM), X-ray photoelectron (XPS) and energy dispersive X-ray spectroscopy (EDS). The number of surface acid sites determined from temperature programmed desorption of ammonia (NH{sub 3}-TPD) were in the range of 0.3-1.5 mmol/g while the active surface areas are estimated to comprise 5-54% of the total surface areas. Finally, the conversion temperatures for the isopropanol dehydration were lowered by as much as 100 C by transitioning from the least acidic to the most acidic catalysts surface.

  19. An Examination of the Carbon Isotope Effects Associated with Amino Acid Biosynthesis

    NASA Astrophysics Data System (ADS)

    Scott, James H.; O'Brien, Diane M.; Emerson, David; Sun, Henry; McDonald, Gene D.; Salgado, Antonio; Fogel, Marilyn L.

    2006-12-01

    Stable carbon isotope ratios (δ13C) were determined for alanine, proline, phenylalanine, valine, leucine, isoleucine, aspartate (aspartic acid and asparagine), glutamate (glutamic acid and glutamine), lysine, serine, glycine, and threonine from metabolically diverse microorganisms. The microorganisms examined included fermenting bacteria, organotrophic, chemolithotrophic, phototrophic, methylotrophic, methanogenic, acetogenic, acetotrophic, and naturally occurring cryptoendolithic communities from the Dry Valleys of Antarctica. Here we demonstrated that reactions involved in amino acid biosynthesis can be used to distinguish amino acids formed by life from those formed by nonbiological processes. The unique patterns of δ13C imprinted by life on amino acids produced a biological bias. We also showed that, by applying discriminant function analysis to the δ13C value of a pool of amino acids formed by biological activity, it was possible to identify key aspects of intermediary carbon metabolism in the microbial world. In fact, microorganisms examined in this study could be placed within one of three metabolic groups: (1) heterotrophs that grow by oxidizing compounds containing three or more carbon-to-carbon bonds (fermenters and organotrophs), (2) autotrophs that grow by taking up carbon dioxide (chemolitotrophs and phototrophs), and (3) acetoclastic microbes that grow by assimilation of formaldehyde or acetate (methylotrophs, methanogens, acetogens, and acetotrophs). Furthermore, we demonstrated that cryptoendolithic communities from Antarctica grouped most closely with the autotrophs, which indicates that the dominant metabolic pathways in these communities are likely those utilized for CO2 fixation. We propose that this technique can be used to determine the dominant metabolic types in a community and reveal the overall flow of carbon in a complex ecosystem.

  20. Dissolution rates of carbonated hydroxyapatite in hydrochloric acid.

    PubMed

    Hankermeyer, Christine R; Ohashi, Kevin L; Delaney, David C; Ross, John; Constantz, Brent R

    2002-02-01

    Osteoclasts have been shown to dissolve efficiently and effectively the mineral phase of bone by locally controlling the environment surrounding the cell. Although this mineral phase has been identified and well characterized as carbonated hydroxyapatite, there is little understanding of the factors that affect the dissolution properties of this mineral phase. Mimicking the mechanism by which osteoclasts dissolve the mineral phase of bone may provide insight into methods for the decalcification of atherosclerotic mineral deposits in the vascular system. Accordingly, a detailed characterization of the effects of various chemical and mechanical parameters on the dissolution of carbonated hydroxyapatite mineral was investigated in this study. Increases in the mineral dissolution rate (2-10 times) were associated with increases in dissolving solution [H+], osmolality, temperature, and flow rate. Mineral dissolution rate increases (5-8 times) were associated with greater surface area of the mineral and mechanical agitation of the dissolving solution. PMID:11771694

  1. Carbonic acid as a reserve of carbon dioxide on icy moons: The formation of carbon dioxide (CO{sub 2}) in a polar environment

    SciTech Connect

    Jones, Brant M.; Kaiser, Ralf I.; Strazzulla, Giovanni

    2014-06-20

    Carbon dioxide (CO{sub 2}) has been detected on the surface of several icy moons of Jupiter and Saturn via observation of the ν{sub 3} band with the Near-Infrared Mapping Spectrometer on board the Galileo spacecraft and the Visible-Infrared Mapping Spectrometer on board the Cassini spacecraft. Interestingly, the CO{sub 2} band for several of these moons exhibits a blueshift along with a broader profile than that seen in laboratory studies and other astrophysical environments. As such, numerous attempts have been made in order to clarify this abnormal behavior; however, it currently lacks an acceptable physical or chemical explanation. We present a rather surprising result pertaining to the synthesis of carbon dioxide in a polar environment. Here, carbonic acid was synthesized in a water (H{sub 2}O)-carbon dioxide (CO{sub 2}) (1:5) ice mixture exposed to ionizing radiation in the form of 5 keV electrons. The irradiated ice mixture was then annealed, producing pure carbonic acid which was then subsequently irradiated, recycling water and carbon dioxide. However, the observed carbon dioxide ν{sub 3} band matches almost exactly with that observed on Callisto; subsequent temperature program desorption studies reveal that carbon dioxide synthesized under these conditions remains in solid form until 160 K, i.e., the sublimation temperature of water. Consequently, our results suggest that carbon dioxide on Callisto as well as other icy moons is indeed complexed with water rationalizing the shift in peak frequency, broad profile, and the solid state existence on these relatively warm moons.

  2. Quantifying global warming from the retreat of glaciers

    SciTech Connect

    Oerlemans, J. )

    1994-04-08

    Records of glacier fluctuations compiled by the World Glacier Monitoring Service can be used to derive an independent estimate of global warming during the last 100 years. Records of different glaciers are made comparable by a two-step scaling procedure; one allowing for differences in glacier geometry, the other for differences in climate sensitivity. The retreat of glaciers during the last 100 years appears to be coherent over the globe. On the basis of modeling of the climate sensitivity of glaciers, the observed glacier retreat can be explained by a linear warming trend of 0.66 kelvin per century.

  3. Carbon isotopic fractionation in the biosynthesis of bacterial fatty acids. Ozonolysis of unsaturated fatty acids as a means of determining the intramolecular distribution of carbon isotopes

    NASA Astrophysics Data System (ADS)

    Monson, K. David; Hayes, J. M.

    1982-02-01

    Methods for the determination of 13C abundances at individual olefinic carbon positions have been developed, tested, and shown to perform accurately. (1) The double bond is oxidized with ozone; (2) silver oxide is used to cleave the resulting ozonide quantitatively to carboxylic-acid fragments; (3) a modified Schmidt decarboxylation is used to produce CO 2 quantitatively from the carboxyl groups of the separated cleavage products; (4) the CO 2 is utilized for mass spectrometric analysis. The results of intramolecular isotopic analyses are combined with molecular-average isotopic compositions determined by total combustion in order to show that fatty acids biosynthesized by Escherichia coli grown aerobically with glucose as the sole carbon source and harvested at late log phase are depleted by approximately 3%. in 13C relative to the glucose. This fractionation arises in the formation of acetylcoenzyme A by pyruvate dehydrogenase and is localized at the carboxyl position in the acetyl-CoA product. The isotopic order in that two-carbon subunit is carried through the biosynthesis of fatty acids so that alternate positions in the fatty-acid chains are depleted in 13C by an amount equal to twice the molecular-average depletion. The kinetic isotope effect at C-2 for pyruvate dehydrogenase in vivo is shown to be approximately 2.3%. While it appears that no other fractionation mechanism has controlled the overall depletion of 13C in these fatty acids, a separate process responsible for control of isotopic abundances in the carboxyl groups has been identified and described elsewhere [Monson K.D. and Hayes J.M. (1980) J. Biol. Chem. 255, 11435-11441]. It is concluded that kinetic, rather than thermodynamic, factors have controlled isotopic distributions in these cells and that kinetic factors will be dominant in most biological reactions.

  4. Recovery of calcium carbonate from steelmaking slag and utilization for acid mine drainage pre-treatment.

    PubMed

    Mulopo, J; Mashego, M; Zvimba, J N

    2012-01-01

    The conversion of steelmaking slag (a waste product of the steelmaking process) to calcium carbonate (CaCO(3)) was tested using hydrochloric acid, ammonium hydroxide and carbon dioxide via a pH-swing process. Batch reactors were used to assess the technical feasibility of calcium carbonate recovery and its use for pre-treatment of acid mine drainage (AMD) from coal mines. The effects of key process parameters, such as the amount of acid (HCl/calcium molar ratio), the pH and the CO(2) flow rate were considered. It was observed that calcium extraction from steelmaking slag significantly increased with an increase in the amount of hydrochloric acid. The CO(2) flow rate also had a positive effect on the carbonation reaction rate but did not affect the morphology of the calcium carbonate produced for values less than 2 L/min. The CaCO(3) recovered from the bench scale batch reactor demonstrated effective neutralization ability during AMD pre-treatment compared with the commercial laboratory grade CaCO(3). PMID:22643421

  5. Multi-walled carbon nanotubes in aqueous phytic acid for enhancing biosensor

    NASA Astrophysics Data System (ADS)

    Guo, Xiaoyu; Miao, Yun; Ye, Pingping; Wen, Ying; Yang, Haifeng

    2014-04-01

    The poor dispersion of carbon based nanomaterials without strong acid pretreatment in aqueous solution is a fundamental problem, limiting its applications in biology-related fields. A good dispersion of multi-walled carbon nanotubes (MWCNTs) in water was realized by 50 wt.% phytic acid (PA) solution. As an application case, the PA-MWCNTs dispersion in aqueous solution was used for the immobilization of horseradish peroxidase (HRP) and its direct electrochemistry was realized. The constructed biosensor has a sound limit of detection, wide linear range, and high affinity for hydrogen peroxide (H2O2) as well as being free from interference of co-existing electro-active species.

  6. Removal of free fatty acid in Palm Fatty Acid Distillate using sulfonated carbon catalyst derived from biomass wastefor biodiesel production

    NASA Astrophysics Data System (ADS)

    Hidayat, Arif; Rochmadi; Wijaya, Karna; Budiman, Arief

    2016-01-01

    In this research, the esterification of PFAD using the sulfonatedcoconut shell biochar catalyst was studied. Carbon solid catalysts were prepared by a sulfonation of carbonized coconut shells. The performances of the catalysts were evaluated in terms of the reaction temperatures, the molar ratios of methanol to PFAD, the catalyst loading and the reaction times. The reusability of the solid acid carbon catalysts was also studied in this work. The results indicated that the FFA conversion was significantly increased with increasing catalyst loading and reaction times. It can be concluded that the optimal conditions were an PFAD to methanol molar ratio of 1:12, the amount of catalyst of 10%w, and reaction temperature of 60oC.At this optimum condition, the conversion to biodieselreached 88%.

  7. Carbon honeycomb grids for advanced lead-acid batteries. Part III: Technology scale-up

    NASA Astrophysics Data System (ADS)

    Kirchev, A.; Serra, L.; Dumenil, S.; Brichard, G.; Alias, M.; Jammet, B.; Vinit, L.

    2015-12-01

    The carbon honeycomb grid technology employs new carbon/carbon composites with ordered 3D structure instead of the classic lead-acid battery current collectors. The technology is laboratory scaled up from small size grids corresponding to electrodes with a capacity of 3 Ah to current collectors suitable for assembly of lead-acid batteries covering the majority of the typical lead-acid battery applications. Two series of 150 grids each (one positive and one negative) are manufactured using low-cost lab-scale equipment. They are further subjected to pasting with active materials and the resulting battery plates are assembled in 12 V AGM-VLRA battery mono-blocks for laboratory testing and outdoor demonstration in electric scooter replacing its original VRLAB pack. The obtained results demonstrate that the technology can replace successfully the state of the art negative grids with considerable benefits. The use of the carbon honeycomb grids as positive plate current collectors is limited by the anodic corrosion of the entire structure attacking both the carbon/carbon composite part and the electroplated lead-tin alloy coating.

  8. Rhizosphere bacterial carbon turnover is higher in nucleic acids than membrane lipids: implications for understanding soil carbon cycling

    PubMed Central

    Malik, Ashish A.; Dannert, Helena; Griffiths, Robert I.; Thomson, Bruce C.; Gleixner, Gerd

    2015-01-01

    Using a pulse chase 13CO2 plant labeling experiment we compared the flow of plant carbon into macromolecular fractions of rhizosphere soil microorganisms. Time dependent 13C dilution patterns in microbial cellular fractions were used to calculate their turnover time. The turnover times of microbial biomolecules were found to vary: microbial RNA (19 h) and DNA (30 h) turned over fastest followed by chloroform fumigation extraction-derived soluble cell lysis products (14 days), while phospholipid fatty acids (PLFAs) had the slowest turnover (42 days). PLFA/NLFA 13C analyses suggest that both mutualistic arbuscular mycorrhizal and saprophytic fungi are dominant in initial plant carbon uptake. In contrast, high initial 13C enrichment in RNA hints at bacterial importance in initial C uptake due to the dominance of bacterial derived RNA in total extracts of soil RNA. To explain this discrepancy, we observed low renewal rate of bacterial lipids, which may therefore bias lipid fatty acid based interpretations of the role of bacteria in soil microbial food webs. Based on our findings, we question current assumptions regarding plant-microbe carbon flux and suggest that the rhizosphere bacterial contribution to plant assimilate uptake could be higher. This highlights the need for more detailed quantitative investigations with nucleic acid biomarkers to further validate these findings. PMID:25914679

  9. Effect of acid rain on calcium carbonate saturation in the Albemarle sound of North Carolina

    SciTech Connect

    Rudolph, K.A.; Burgess, S.K.; Willey, J.D.; Kieber, R.J.

    1996-10-01

    The effects of acidic rainwater additions on calcium carbonate solubility and alkalinity in the poorly buffered, biologically active and commercially important waters of the Albemarle Sound, NC are reported. Samples collected monthly at four sites were analyzed for salinity, pK total alkalinity, and calcium concentrations. Five percent and 10% dilutions of sulfuric acid at pH 4, mimicking acid rain additions, were added and total alkalinity and calcium concentrations again determined. The addition of acid decreased the alkalinity in the Albemarle samples by as much as 15%, although the magnitude of the impact depended both on site and season. The effects of acid additions on dissolved calcium concentrations were more variable,. and also displayed a site and season dependency. Calcium concentrations, alkalinity, and pH values were also determined during controlled laboratory experiments, where 25 mg/L Callinectes sapidus shells were added to Albemarle Sound water. All three analytes increased significantly upon acid additions relative to controls.

  10. Stable carbon isotopic compositions of organic acids in total suspended particles and dusts from Guangzhou, China

    NASA Astrophysics Data System (ADS)

    Ma, Shexia; Peng, Ping'an; Song, Jianzhong; Zhao, Jinping; He, Lulu; Sheng, Guoying; Fu, Jiamo

    2010-10-01

    Stable carbon isotopic compositions of individual organic acids were determined in total suspended particles and dusts from Guangzhou. The δ 13C values of high molecular weight n-alkanoic acids (C 20-C 28) varied from -34.1‰ to -32.4‰ and tended to be heavier in summer and lighter in winter. These δ 13C values indicate that high molecular weight n-alkanoic acids were derived mainly from emission by C 3 plants. Reduced biological synthesis of high molecular weight n-alkanoic acids in winter may be the reason for the light carbon isotopic composition. The δ 13C values of low molecular weight n-alkanoic acids (C 10-C 18) changed from -31.7‰ to -30.3‰ and exhibited a reverse seasonal trend, i.e., heavier in winter and lighter in summer. Slightly heavier δ 13C values of low molecular weight n-alkanoic acids than those of high molecular weight n-alkanoic acids suggested that they may be emitted from blended sources, e.g., anthropogenic sources and vegetation waxes. Lighter δ 13C values in summer may be attributed to relatively low anthropogenic sources and high botanic sources in summer. Dicarboxylic acids and aromatic acids have been proposed as secondary products from photochemical degradation. The average δ 13C values of dicarboxylic acids and aromatic acids were heavier, and ranged from -25.2‰ to -22.9‰ and from -30.0‰ to -27.6‰, respectively. Both dicarboxylic acids and aromatic acids displayed the same temporal variations in the δ 13C values, i.e., negative δ 13C in the summer samples and positive in the winter samples, which may be controlled by photochemical reactions; they are generally severe in winter in Guangzhou under the monsoon weather system. The heaviest δ 13C values were observed in dicarboxylic acids, indicating that dicarboxylic acids were formed by fast and more complete oxidation reactions. These results indicate that the stable carbon isotopic composition of organic acids may provide important information about sources and

  11. Hierarchical carbon nanotube assemblies created by sugar-boric or boronic acid interactions.

    PubMed

    Tamesue, Shingo; Numata, Munenori; Kaneko, Kenji; James, Tony D; Shinkai, Seiji

    2008-10-01

    We previously found that polysaccharide "schizophyllan (SPG)" can entrap as-grown and cut single-walled carbon nanotubes (as-SWNTs and c-SWNTs, respectively): we here reported that the c-SWNT-s-SPG (single stranded SPG) composites thus obtained can be aligned regularly using the covalent bond formation between boric acid or boronic acid derivatives and the 4,6-dihydroxyl group of the glucose side-chain unit. PMID:18802596

  12. Highly efficient extraction of cellular nucleic acid associated proteins in vitro with magnetic oxidized carbon nanotubes.

    PubMed

    Zhang, Yi; Hu, Zhengyan; Qin, Hongqiang; Wei, Xiaoluan; Cheng, Kai; Liu, Fangjie; Wu, Ren'an; Zou, Hanfa

    2012-12-01

    Nucleic acid associated proteins (NAaP) play the essential roles in gene regulation and protein expression. The global analysis of cellular NAaP would give a broad insight to understand the interaction between nucleic acids and the associated proteins, such as the important proteinous regulation factors on nucleic acids. Proteomic analysis presents a novel strategy to investigate a group of proteins. However, the large scale analysis of NAaP is yet impossible due to the lack of approaches to harvest target protein groups with a high efficiency. Herein, a simple and efficient method was developed to collect cellular NAaP using magnetic oxidized carbon nanotubes based on the strong interaction between carbon nanotubes and nucleic acids along with corresponding associated proteins. We found that the magnetic oxidized carbon nanotubes demonstrated a nearly 100% extraction efficiency for intracellular nucleic acids from cells in vitro. Importantly, the proteins associated on nucleic acids could be highly efficiently harvested using magnetic oxidized carbon nanotubes due to the binding of NAaP on nucleic acids. 1594 groups of nuclear NAaP and 2595 groups of cellular NAaP were extracted and identified from about 1,000,000 cells, and 803 groups of NAaP were analyzed with only about 10,000 cells, showing a promising performance for the proteomic analysis of NAaP from minute cellular samples. This highly efficient extraction strategy for NAaP is a simple approach to identify cellular nucleic acid associated proteome, and we believed this strategy could be further applied in systems biology to understand the gene expression and regulation. PMID:23121485

  13. Efficient optical resolution of amino acid by alanine racemaze chiral analogue supported on mesoporous carbon

    NASA Astrophysics Data System (ADS)

    Jang, D.; Kim, K.; Park, D.; Kim, G.

    2012-09-01

    Optically pure D-amino acids are industrially important chiral building blocks for the synthesis of pharmaceuticals, food ingredients, and drug intermediates. Chemoenzymatic dynamic kinetic-resolution processes have recently been developed for deracemization of amino acids. S-ARCA would be a good candidate for the selective adsorption of D amino acid through the imine formation reaction. The organic phase containing S-ARCA adsorbent, TPPC or Ionic Liquid (as a phase transfer catalyst) in MC were coated on the surfaces of mesoporous carbon C-SBA-15(CMK). The aqueous solution of racemic D/L-amino acid and NaOH were added to the carbon support coated with ARCA. The D/L ratios on ARCA and in solution were determined with increasing reaction time. S-ARCA has a unique property for the selective adsorption of D- amino acid (up to 90% selcetivity) in the racemic mixture. The fixed bed reactor containing ARCA/carbon support was also adopted successfully for the selective separation of amino acid.

  14. On the neutralization of acid rock drainage by carbonate and silicate minerals

    NASA Astrophysics Data System (ADS)

    Sherlock, E. J.; Lawrence, R. W.; Poulin, R.

    1995-02-01

    The net result of acid-generating and-neutralizing reactions within mining wastes is termed acid rock drainage (ARD). The oxidation of sulfide minerals is the major contributor to acid generation. Dissolution and alteration of various minerals can contribute to the neutralization of acid. Definitions of alkalinity, acidity, and buffer capacity are reviewed, and a detailed discussion of the dissolution and neutralizing capacity of carbonate and silicate minerals related to equilibium conditions, dissolution mechanism, and kinetics is provided. Factors that determine neutralization rate by carbonate and silicate minerals include: pH, PCO 2, equilibrium conditions, temperature, mineral composition and structure, redox conditions, and the presence of “foreign” ions. Similar factors affect sulfide oxidation. Comparison of rates shows sulfides react fastest, followed by carbonates and silicates. The differences in the reaction mechanisms and kinetics of neutralization have important implications in the prediction, control, and regulation of ARD. Current static and kinetic prediction methods upon which mine permitting, ARD control, and mine closure plans are based do not consider sample mineralogy or the kinetics of the acid-generating and-neutralizing reactions. Erroneous test interpretations and predictions can result. The importance of considering mineralogy for site-specific interpretation is highlighted. Uncertainty in prediction leads to difficulties for the mine operator in developing satisfactory and cost-effective control and remediation measures. Thus, the application of regulations and guidelines for waste management planning need to beflexible.

  15. Predicting sorption of organic acids to a wide range of carbonized sorbents

    NASA Astrophysics Data System (ADS)

    Sigmund, Gabriel; Kah, Melanie; Sun, Huichao; Hofmann, Thilo

    2016-04-01

    Many contaminants and infochemicals are organic acids that undergo dissociation under environmental conditions. The sorption of dissociated anions to biochar and other carbonized sorbents is typically lower than that of neutral species. It is driven by complex processes that are not yet fully understood. It is known that predictive approaches developed for neutral compounds are unlikely to be suitable for organic acids, due to the effects of dissociation on sorption. Previous studies on the sorption of organic acids to soils have demonstrated that log Dow, which describes the decrease in hydrophobicity of acids upon dissociation, is a useful alternative to log Kow. The aim of the present study was to adapt a log Dow based approach to describe the sorption of organic acids to carbonized sorbents. Batch experiments were performed with a series of 9 sorbents (i.e., carbonized wood shavings, pig manure, and sewage sludge, carbon nanotubes and activated carbon), and four acids commonly used for pesticidal and biocidal purposes (i.e., 2,4-D, MCPA, 2,4-DB, and triclosan). Sorbents were comprehensively characterized, including by N2 and CO2 physisorption, Fourier transform infrared spectroscopy, and elemental analysis. The wide range of sorbents considered allows (i) discussing the mechanisms driving the sorption of neutral and anionic species to biochar, and (ii) their dependency on sorbate and sorbent properties. Results showed that the sorption of the four acids was influenced by factors that are usually not considered for neutral compounds (i.e., pH, ionic strength). Dissociation affected the sorption of the four compounds, and sorption of the anions ranged over five orders of magnitude, thus substantially contributing to sorption in some cases. For prediction purposes, most of the variation in sorption to carbonized sorbents (89%) could be well described with a two-parameter regression equation including log Dow and sorbent specific surface area. The proposed model

  16. Promoting Writing for Research: The "Writing Retreat" Model

    ERIC Educational Resources Information Center

    Singh, R. J.

    2012-01-01

    Research papers take a long time to write and in an academic environment where the "publish or perish" clause applies, writing retreats are a way of creating time and space to write academic articles in a concentrated period of time. This article examines ways in which academics can write more articles for publication. In particular it focuses on…

  17. Scientists Discover New Possibilities at Scientific Investigators Retreat | Poster

    Cancer.gov

    By Nancy Parrish, Staff Writer; photos by Richard Frederickson, Staff Photographer Scientists who attended the 2015 NCI Intramural Scientific Investigators Retreat on Jan. 13 had a chance to discuss research results with other investigators from across the National Cancer Institute. And this year, they could also explore new possibilities for the future of their research.

  18. Strategic planning: it's worth the effort. Homework makes retreats work.

    PubMed

    Hansen, Richard D

    2003-09-01

    Medical groups that achieve superior operational and financial performance frequently have leaders who take time to hold strategic planning retreats. These gatherings allow practice leaders to address difficult issues such as expansion, compensation structure and governance--away from the workplace and facilitated by an outsider. The result: organizational direction that all leaders help shape and commit to. PMID:14535084

  19. Jumpstarting Junior Faculty Motivation and Performance with Focused Writing Retreats

    ERIC Educational Resources Information Center

    Girardeau, Laura; Rud, A. G.; Trevisan, Michael S.

    2014-01-01

    Faculty members are critical assets to universities, and large losses to institutions occur if they are not successful. Although institutions value publications and grants in the tenure process, newer professors receive little guidance in writing for these endeavors. Faculty writing retreats help apprentice professors in the craft of writing;…

  20. Exploring the Effectiveness of a Retreat Method for Extension Staff

    ERIC Educational Resources Information Center

    Worker, Steven M.; Hill, Russell D.; Miller, JoLynn C.; Go, Charles G.; Boyes, Rita J.

    2015-01-01

    The California 4-H Association hosted two retreats to support its members with goals of balancing professional development with intentional relationship building. Evaluations demonstrated that staff found the intentional balance of time spent in unstructured, semi-structured, and structured time offered opportunities to grow professionally while…

  1. Carbon dioxide and organic acids: origin and role in burial diagenesis (Texas Gulf Coast Tertiary)

    SciTech Connect

    Lundegard, P.D.

    1985-01-01

    Carbon dioxide produced by decarboxylation of organic matter is not a dominant factor in secondary porosity development. Material balance calculations indicate the amount of feldspar and carbonate dissolution that has taken place in Tertiary sandstones of the Texas Gulf Coast far exceeds that which is explainable by decarboxylation. Other potential sources of acid for dissolution reactions include reverse weathering reactions in shales, an hydrous pyrolysis reactions between organic carbon and oxygen in H/sub 2/O to yield CO/sub 2/ or organic acids. Considerations of CO/sub 2/ solubility and the temperature distribution of organic acids imply that these species must be generated locally to cause significant dissolution. The CO/sub 2/ content of gas from Gulf Coast Tertiary sandstones is proportional to reservoir age, and increases with depth and temperature at a rate that is approximately exponential. In the Wilcox Formation the increase in CO/sub 2/ content continues beyond depths where dissolved organic acids are abundant and where kerogen has lost its oxygen from functional groups that are readily liberated as CO/sub 2/. In this formation the /sup 13/C of CO/sub 2/ and CH/sub 4/ are proportional to temperature and to each other. Either mixing with fluids derived from the Mesozoic carbonate section of deep CO/sub 2/ generation by kinetically controlled organic reactions may explain these data. Organic acid concentration with depth and temperature indicates a non-biological origin by thermal cracking of kerogen during burial. Continued burial leads to their thermal decomposition. Cessation of burial may lead to meteoric water invasion and organic acid destruction by biological processes. The effect of time on organic acid production is minor compared to temperature.

  2. Carbon Isotopic Ratios of Amino Acids in Stardust-Returned Samples

    NASA Technical Reports Server (NTRS)

    Elsila, Jamie E.; Glavin, Daniel P.; Dworkin, Jason P.

    2009-01-01

    NASA's Stardust spacecraft returned to Earth samples from comet 81P/Wild 2 in January 2006. Preliminary examinations revealed the presence of a suite of organic compounds including several amines and amino acids, but the origin of these compounds could not be identified. Here. we present the carbon isotopic ratios of glycine and E-aminocaproic acid (EACH), the two most abundant amino acids observed, in Stardust-returned foil samples measured by gas chromatography-combustion-isotope ratio crass spectrometry coupled with quadrupole mass spectrometry (GC-QMS/IRMS).

  3. Carbon Isotopic Measurements of Amino Acids in Stardust-Returned Samples

    NASA Technical Reports Server (NTRS)

    Elsila, Jamie

    2009-01-01

    NASA's Stardust spacecraft returned to Earth samples from comet 81P/Wild 2 in January 2006. Preliminary examinations revealed the presence of a suite of organic compounds including several amines and amino acids, but the origin of these compounds could not be identified. Here, we present the carbon isotopic ratios of glycine and e-aminocaproic acid (EACA), the two most abundant amino acids, in Stardust-returned foil samples measured by gas chromatography-combustion-isotope ratio mass spectrometry coupled with quadrupole mass spectrometry (GC-CAMS/IRMS).

  4. Modeling and optimizing the design of matrix treatments in carbonate reservoirs with self-diverting acid systems

    NASA Astrophysics Data System (ADS)

    Bulgakova, G. T.; Kharisov, R. Ya; Sharifullin, A. R.; Pestrikov, A. V.

    2015-01-01

    Application of a self-diverting-acid based on viscoelastic surfactant (SDVA) is a promising technology for improving the efficacy of acid treatment in oil and gas-bearing carbonate reservoirs. In this study, we present a mathematical model for assessing SDVA flow and reaction with carbonate rock using the SDVA rheological characteristics. The model calculates the technological parameters for acidizing operations and the prediction of well productivity after acid treatment, in addition to technical and economic optimization of the acidizing process by modeling different acid treatment options with varying volumes, injection rates, process fluids stages and initial economic scenarios.

  5. Synergistic effect of self-assembled carboxylic acid-functionalized carbon nanotubes and carbon fiber for improved electro-activated polymeric shape-memory nanocomposite

    NASA Astrophysics Data System (ADS)

    Lu, Haibao; Min Huang, Wei

    2013-06-01

    The present work studies the synergistic effect of self-assembled carboxylic acid-functionalized carbon nanotube (CNT) and carbon fiber on the electrical property and electro-activated recovery behavior of shape memory polymer (SMP) nanocomposites. The combination of CNT and carbon fiber results in improved electrical conductivity in the SMP nanocomposites. Carboxylic acid-functionalized CNTs are grafted onto the carbon fibers and then self-assembled by deposition to significantly enhance the reliability of the bonding between carbon fiber and SMP via van der Waals and covalent crosslink. Furthermore, the self-assembled carboxylic acid-functionalized CNTs and carbon fibers enable the SMP nanocomposites for Joule heating triggered shape recovery.

  6. Carbon and Oxygen Isotope Measurements of Ordinary Chondrite (OC) Meteorites from Antarctica Indicate Distinct Terrestrial Carbonate Species using a Stepped Acid Extraction Procedure Impacting Mars Carbonate Research

    NASA Astrophysics Data System (ADS)

    Evans, M. E.; Niles, P. B.; Locke, D.

    2015-12-01

    The purpose of this study is to characterize the stable isotope values of terrestrial, secondary carbonate minerals from five OC meteorites collected in Antarctica. These samples were selected for analysis based upon their size and collection proximity to known Martian meteorites. They were also selected based on petrologic type (3+) such that they were likely to be carbonate-free before falling to Earth. This study has two main tasks: 1) characterize the isotopic composition of terrestrial, secondary carbonate minerals formed on meteorites in Antarctica, and 2) study the mechanisms of carbonate formation in cold and arid environments with Antarctica as an analog for Mars. Two samples from each meteorite, each ~0.5g, was crushed and dissolved in pure phosphoric acid for 3 sequential reactions: a) Rx0 for 1 hour at 30°C, b) Rx1 for 18 hours at 30°C, and c) Rx2 for 3 hours at 150°C. CO2 was distilled by freezing with liquid nitrogen from each sample tube, then separated from organics and sulfides with a TRACE GC using a Restek HayeSep Q 80/100 6' 2mm stainless column, and then analyzed on a Thermo MAT 253 IRMS in Dual Inlet mode. This system was built at NASA/JSC over the past 3 years and proof tested with known carbonate standards to develop procedures, assess yield, and quantify expected uncertainties. Two distinct species of carbonates are found based on the stepped extraction technique: 1) Ca-rich carbonate released at low temperatures, and 2) Mg, or Fe-rich carbonate released at high temperatures. Preliminary results indicate that most of the carbonates present in the ordinary chondrites analyzed have δ13C=+5‰, which is consistent with formation from atmospheric CO2 δ13C=-7‰ at -20°C. The oxygen isotopic compositions of the carbonates vary between +4‰ and +34‰ with the Mg-rich and/or Fe-rich carbonates possessing the lowest δ18O values. This suggests that the carbonates formed under a wide range of temperatures. However, the carbonate oxygen

  7. Microbial mediated formation of Fe-carbonate minerals under extreme acidic conditions

    PubMed Central

    Sánchez-Román, Mónica; Fernández-Remolar, David; Amils, Ricardo; Sánchez-Navas, Antonio; Schmid, Thomas; Martin-Uriz, Patxi San; Rodríguez, Nuria; McKenzie, Judith A.; Vasconcelos, Crisogono

    2014-01-01

    Discovery of Fe-carbonate precipitation in Rio Tinto, a shallow river with very acidic waters, situated in Huelva, South-western Spain, adds a new dimension to our understanding of carbonate formation. Sediment samples from this low-pH system indicate that carbonates are formed in physico-chemical conditions ranging from acid to neutral pH. Evidence for microbial mediation is observed in secondary electron images (Fig. 1), which reveal rod-shaped bacteria embedded in the surface of siderite nanocrystals. The formation of carbonates in Rio Tinto is related to the microbial reduction of ferric iron coupled to the oxidation of organic compounds. Herein, we demonstrate for the first time, that Acidiphilium sp. PM, an iron-reducing bacterium isolated from Rio Tinto, mediates the precipitation of siderite (FeCO3) under acidic conditions and at a low temperature (30°C). We describe nucleation of siderite on nanoglobules in intimate association with the bacteria cell surface. This study has major implications for understanding carbonate formation on the ancient Earth or extraterrestrial planets. PMID:24755961

  8. Polymerization of euphorbia oil with Lewis acid in carbon dioxide media

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Boron trifluoride diethyl etherate (BF3-OEt2) Lewis acid catalyzed ring-opening polymerization of euphorbia oil (EO), a natural epoxy oil, in liquid carbon dioxide was conducted in an effort to develop useful vegetable oil based polymers. The resulting polymers (RPEO) were characterized by FTIR, 1H-...

  9. EFFECT OF ACID TREATMENT ON DISSOLVED ORGANIC CARBON RETENTION BY A SPODIC HORIZON

    EPA Science Inventory

    Processes involving the movement of organic substances in forest soils are not well understood. This study was conducted to examine the role of acidic inputs on dissolved organic carbon (DOC) mobility, processes affecting the retention of DOV by a B horizon, and SO2-4 adsorption....

  10. Numbers of bacteria recovered from broiler carcasses and chiller water treated with hypochlorous and carbonic acids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A study was conducted to determine the effects of treating poultry chiller water with a mixture of hypochlorous and carbonic acids. Broiler carcasses and chiller water were obtained from a commercial processing facility which had recently installed a TOMCO Pathogen Management SystemJ to recycle wat...

  11. FATTY ACID STABLE ISOTOPE INDICATORS OF MICROBIAL CARBON SOURCE IN TROPICAL SOILS

    EPA Science Inventory

    The soil microbial community plays an important role in tropical ecosystem functioning because of its importance in the soil organic matter (SOM) cycle. We have measured the stable carbon isotopic ratio (delta13C) of individual phospholipid fatty acids (PLFAs) in a variety of tr...

  12. Neutralizing Carbonic Acid in Deep Carbonate Strata below the North Atlantic

    SciTech Connect

    Daniel P. Schrag

    2005-12-01

    Our research is aimed at investigating several technical issues associated with carbon dioxide sequestration in calcium carbonate sediments below the sea floor through laboratory experiments and chemical transport modeling. Our goal is to evaluate the basic feasibility of this approach, including an assessment of optimal depths, sediment types, and other issues related to site selection. Through laboratory and modeling efforts, we are studying the flow of liquid carbon dioxide and carbon dioxide-water mixtures through calcium carbonate sediments to better understand the geomechanical and structural stability of the sediments during and after injection. Our modeling efforts in the first year show that the idea is feasible, but requires more sophisticated analysis of fluid flow at high pressure in deep sea sediments. In addition, we are investigating the kinetics of calcium carbonate dissolution in the presence of CO{sub 2}-water fluids, which is a critical feature of the system as it allows for increased permeability during injection. Our experimental results from the first year of work have shown that the kinetics are likely to be fast enough to create dissolution which will affect permeability. However, additional experiments are needed at high pressures, which will be a focus for years 2 and 3. We are also investigating the possibility of carbon dioxide hydrate formation in the pore fluid, which might complicate the injection procedure by reducing sediment permeability but might also provide an upper seal in the sediment-pore fluid system, preventing release of CO{sub 2} into the deep ocean, particularly if depth and temperature at the injection point rule out immediate hydrate formation. Finally, we are in the beginning stages of an economic analysis to estimate costs of drilling and gas injection, site monitoring as well as the availability of potential disposal sites with particular emphasis on those sites that are within the 200-mile economic zone of the

  13. Acid rain damage to carbonate stone: a quantitative assessment based on the aqueous geochemistry of rainfall runoff from stone

    USGS Publications Warehouse

    Reddy, M.M.

    1988-01-01

    An onsite experimental procedure was used to identify and quantify acid rain damage to carbonate stone, based on the change in rain runoff chemical composition. Onsite data obtained during the summer and fall of 1984 at three locations in the northeastern United States indicate that carbonate stone surface recession is related to acid deposition. -from Author

  14. Characteristics and Treatment Outcomes of Retreatment Tuberculosis Patients in Benin

    PubMed Central

    Ade, Serge; Adjibodé, Omer; Wachinou, Prudence; Toundoh, Narcisse; Awanou, Bérénice; Agodokpessi, Gildas; Affolabi, Dissou; Adè, Gabriel; Harries, Anthony D.; Anagonou, Séverin

    2016-01-01

    Objective. To determine among retreatment tuberculosis patients in Benin baseline characteristics, culture, and drug sensitivity testing (DST) results and treatment outcomes. Materials and Methods. A retrospective national cohort study of all retreatment tuberculosis patients in Benin in 2013 using registers and treatment cards. Results. Of 3957 patients with tuberculosis, 241 (6%) were retreatment cases. Compared to new pulmonary bacteriologically confirmed tuberculosis (NPBCT) patients, there were significantly higher numbers of males (P = 0.04), patients from “Atlantique-Littoral” (P = 0.006), patients aged 45–64 years (P = 0.007), and HIV-positive patients (P = 0.04) among those retreated. Overall, 171 (71%) patients submitted sputum for DST, of whom (163) 95% were positive for Mycobacterium tuberculosis on Xpert MTB/RIF and/or culture and 17 (10%) were rifampicin resistant (9 with MDR-TB and 8 monoresistant to rifampicin). For those without MDR-TB (n = 224), treatment success was 93%. Worse outcomes occurred in those with unknown HIV status (RR: 0.27; 0.05–1.45; P < 0.01) while better outcomes occurred in those who relapsed (RR: 1.06, 95 CI: 1.02–1.10, P = 0.04). Conclusion. In 2013, a high proportion of retreatment patients received DST. Treatment success was good although more needs to be done to systematically increase the final follow-up smear examination. Reasons of high losses to follow-up from “Oueme-Plateau” should be investigated. PMID:27110400

  15. Comparison of inhibition effects of some benzoic acid derivatives on sheep heart carbonic anhydrase

    NASA Astrophysics Data System (ADS)

    Kiliç, Deryanur; Yildiz, Melike; Şentürk, Murat; Erdoǧan, Orhan; Küfrevioǧlu, Ömer Irfan

    2016-04-01

    Carbonic anhydrase (CA) is a family of metalloenzymes that requires Zn as a cofactor and catalyze the quick conversion of CO2 to HCO3- and H+. Inhibitors of the carbonic anhydrases (CAs) have medical usage of significant diseases such as glaucoma, epilepsy, gastroduodenal ulcers, acid-base disequilibria and neurological disorders. In the present study, inhibition of CA with some benzoic derivatives (1-6) were investigated. Sheep heart CA (shCA) enzyme was isolated by means of designed affinity chromatography gel (cellulose-benzyl-sulfanylamide) 42.45-fold in a yield of 44 % with 564.65 EU/mg. Purified shCA enzyme was used in vitro studies. In the studies, IC50 values were calculated for 3-aminobenzoic acid (1), 4-aminobenzoic acid (2), 2-hydroxybenzoic acid (3), 2-benzoylbenzoic acid (4), 2,3-dimethoxybenzoic acid (5), and 3,4,5-trimethoxybenzoic acid (6), showing the inhibition effects on the purified enzyme. Such molecules can be used as pioneer for discovery of novel effective CA inhibitors for medicinal chemistry applications.

  16. Adsorption of clofibric acid and ketoprofen onto powdered activated carbon: effect of natural organic matter.

    PubMed

    Gao, Yaohuan; Deshusses, Marc A

    2011-12-01

    The adsorption of two acidic pharmaceutically active compounds (PhACs), clofibric acid and ketoprofen, onto powdered activated carbon (PAC) was investigated with a particular focus on the influence of natural organic matter (NOM) on the adsorption of the PhACs. Suwannee River humic acids (SRHAs) were used as a substitute for NOM. Batch adsorption experiments were conducted to obtain adsorption kinetics and adsorption isotherms with and without SRHAs in the system. The adsorption isotherms and adsorption kinetics showed that the adsorption ofclofibric acid was not significantly affected by the presence of SRHAs at a concentration of 5 mg (as carbon) L(-1). An adsorption capacity of 70 to 140 mg g(-1) was observed and equilibrium was reached within 48 h. In contrast, the adsorption of ketoprofen was markedly decreased (from about 120 mg g(-1) to 70-100 mg g(-1)) in the presence of SRHAs. Higher initial concentrations of clofibric acid than ketoprofen during testing may explain the different behaviours that were observed. Also, the more hydrophobic ketoprofen molecules may have less affinity for PAC when humic acids (which are hydrophilic) are present. The possible intermolecular forces that could account for the different behaviour of clofibric acid and ketoprofen adsorption onto PAC are discussed. In particular, the relevance of electrostatic forces, electron donor-acceptor interaction, hydrogen bonding and London dispersion forces are discussed PMID:22439557

  17. Solubility of small-chain carboxylic acids in supercritical carbon dioxide

    SciTech Connect

    Sparks, Darrell L.; Estevez, L. Antonio; Hernandez, Rafael; McEwen, Jason; French, Todd

    2010-07-08

    The solubility of heptanoic acid and octanoic acid in supercritical carbon dioxide has been determined at temperatures of (313.15, 323.15, and 333.15) K over a pressure range of (8.5 to 30.0) MPa, depending upon the solute. The solubility of heptanoic acid ranged from a solute concentration of (0.08 ± 0.03) kg • m-3 (T = 323.15 K, p = 8.5 MPa) to (147 ± 0.2) kg • m-3 (T = 323.15 K, p = 20.0 MPa). The lowest octanoic acid solubility obtained was a solute concentration of (0.40 ± 0.1) kg • m-3 (T = 333.15 K, p = 10.0 MPa), while the highest solute concentration was (151 ± 2) kg • m-3 (T = 333.15 K, p = 26.7 MPa). In addition, solubility experiments were performed for nonanoic acid in supercritical carbon dioxide at 323.15 K and pressures of (10.0 to 30.0) MPa to add to the solubility data previously published by the authors. In general, carboxylic acid solubility increased with increasing solvent density. The results also showed that the solubility of the solutes decreased with increasing molar mass at constant supercritical-fluid density. Additionally, the efficacy of Chrastil's equation and other density-based models was evaluated for each fatty acid.

  18. Solubility of small-chain carboxylic acids in supercritical carbon dioxide

    DOE PAGESBeta

    Sparks, Darrell L.; Estevez, L. Antonio; Hernandez, Rafael; McEwen, Jason; French, Todd

    2010-07-08

    The solubility of heptanoic acid and octanoic acid in supercritical carbon dioxide has been determined at temperatures of (313.15, 323.15, and 333.15) K over a pressure range of (8.5 to 30.0) MPa, depending upon the solute. The solubility of heptanoic acid ranged from a solute concentration of (0.08 ± 0.03) kg • m-3 (T = 323.15 K, p = 8.5 MPa) to (147 ± 0.2) kg • m-3 (T = 323.15 K, p = 20.0 MPa). The lowest octanoic acid solubility obtained was a solute concentration of (0.40 ± 0.1) kg • m-3 (T = 333.15 K, p = 10.0more » MPa), while the highest solute concentration was (151 ± 2) kg • m-3 (T = 333.15 K, p = 26.7 MPa). In addition, solubility experiments were performed for nonanoic acid in supercritical carbon dioxide at 323.15 K and pressures of (10.0 to 30.0) MPa to add to the solubility data previously published by the authors. In general, carboxylic acid solubility increased with increasing solvent density. The results also showed that the solubility of the solutes decreased with increasing molar mass at constant supercritical-fluid density. Additionally, the efficacy of Chrastil's equation and other density-based models was evaluated for each fatty acid.« less

  19. Dissolution of single-walled carbon nanotubes in alkanol-cholic acid mixtures

    NASA Astrophysics Data System (ADS)

    Dyshin, A. A.; Eliseeva, O. V.; Bondarenko, G. V.; Kiselev, M. G.

    2015-09-01

    A procedure for dispersing the single-walled carbon nanotubes (SWCNTs) for preparing stable suspensions with high concentrations of individual nanotubes in various alcohols was described. The obtained suspensions were studied by Raman spectroscopy. The solubility of the single-walled carbon nanotubes in alcohols was found to depend on the concentration of cholic acid. The ethanol-surfactant mixture was shown to be the best solvent for all alkanol-cholic acid mixtures (0.018 mol/kg) under study used for preparing time-stable suspensions of single-walled carbon nanotubes. The dissolving ability of aliphatic alcohols was found to decrease in the series: ethanol-isopropanol- tert-butanol-butanol-propanol.

  20. Preparation of activated carbon using low temperature carbonisation and physical activation of high ash raw bagasse for acid dye adsorption.

    PubMed

    Valix, M; Cheung, W H; McKay, G

    2004-08-01

    Activated carbons were prepared from bagasse through a low temperature (160 degrees C) chemical carbonisation treatment and gasification with carbon dioxide at 900 degrees C. The merit of low temperature chemical carbonisation in preparing chars for activation was assessed by comparing the physical and chemical properties of activated carbons developed by this technique to conventional methods involving the use of thermal and vacuum pyrolysis of bagasse. In addition, the adsorption properties (acid blue dye) of these bagasse activated carbons were also compared with a commercial activated carbon. The results suggest that despite the high ash content of the precursor, high surface areas (614-1433 m2 g(-1)) and microporous (median pore size from 0.45 to 1.2 nm) activated carbons can be generated through chemical carbonisation and gasification. The micropore area of the activated carbon developed from chars prepared by the low temperature chemical carbonisation provides favourable adsorption sites to acid blue dye (391 mg g(-1) of carbon). The alkalinity of the carbon surface and total surface area were shown to have complementary effects in promoting the adsorption of acid blue dye. Adsorption of the anionic coloured component of the acid dye was shown to be promoted in carbon exhibiting alkaline or positively charged surfaces. This study demonstrates that activated carbons with high acid dye adsorption capacities can be prepared from high ash bagasse based on low temperature chemical carbonisation and gasification. PMID:15212915

  1. Enhancing adsorption efficiency of dichloroacetic acid onto mesoporous carbons: Procedure optimization, mechanism and characterization.

    PubMed

    Ding, Ying; Zhu, Jianzhong; Ji, Dongliang; Cao, Yang; Ling, Xiaojia; Chen, Wei

    2015-08-15

    Highly ordered mesoporous carbon may be directly synthesized via supramolecular self-assembly with in situ evaporation-induced crystallization process by controlling thermal reaction temperatures and carbon mass loading. In the present study, the effects of thermal reaction temperatures on the structural characterization and adsorption capacity of mesoporous carbon have been investigated and analyzed with orthogonal test experiments. The results show the carbonization temperature (R=32.1) plays a more important role than the self-assembly temperature (R=8.5) and thermal polymerization temperature (R=10.1) in manipulating the pore texture structures. The optimization grouping temperature was 40-110-500 °C. The optimum mesoporous carbon sample had the highest BET specific surface area (474 m(2)/g), the largest pore volume (0.46 cm(3)/g), and with reasonable uniform pore size distribution. The adsorption evaluation also shows the adsorption capacity is strongly correlated with the pore structure of mesoporous carbon, the optimized mesoporous carbon sample displayed the largest adsorption capacity (350 mg/g) at an initial concentration of 20.0 mg/L of dichloroacetic acid. The study results indicate optimization of thermal reaction parameters is an effective approach for synthesis of ordered mesoporous carbons. PMID:25935284

  2. Synthesis of sulfonated porous carbon nanospheres solid acid by a facile chemical activation route

    NASA Astrophysics Data System (ADS)

    Chang, Binbin; Guo, Yanzhen; Yin, Hang; Zhang, Shouren; Yang, Baocheng

    2015-01-01

    Generally, porous carbon nanospheres materials are usually prepared via a template method, which is a multi-steps and high-cost strategy. Here, we reported a porous carbon nanosphere solid acid with high surface area and superior porosity, as well as uniform nanospheical morphology, which prepared by a facile chemical activation with ZnCl2 using resorcinol-formaldehyde (RF) resins spheres as precursor. The activation of RF resins spheres by ZnCl2 at 400 °C brought high surface area and large volume, and simultaneously retained numerous oxygen-containing and hydrogen-containing groups due to the relatively low processing temperature. The presence of these functional groups is favorable for the modification of -SO3H groups by a followed sulfonation treating with sulphuric acid and organic sulfonic acid. The results of N2 adsorption-desorption and electron microscopy clearly showed the preservation of porous structure and nanospherical morphology. Infrared spectra certified the variation of surface functional groups after activation and the successful modification of -SO3H groups after sulfonation. The acidities of catalysts were estimated by an indirect titration method and the modified amount of -SO3H groups were examined by energy dispersive spectra. The results suggested sulfonated porous carbon nanospheres catalysts possessed high acidities and -SO3H densities, which endowed their significantly catalytic activities for biodiesel production. Furthermore, their excellent stability and recycling property were also demonstrated by five consecutive cycles.

  3. Culture strategies for lipid production using acetic acid as sole carbon source by Rhodosporidium toruloides.

    PubMed

    Huang, Xiang-Feng; Liu, Jia-Nan; Lu, Li-Jun; Peng, Kai-Ming; Yang, Gao-Xiang; Liu, Jia

    2016-04-01

    Rhodosporidium toruloides AS 2.1389 was tested using different concentrations of acetic acid as a low-cost carbon source for the production of microbial lipids, which are good raw materials for biodiesel production. It grew and had higher lipid contents in media containing 4-20g/L acetic acid as the sole carbon source, compared with that in glucose-containing media under the same culture conditions. At acetic acid concentrations as high as 20g/L and the optimal carbon-to-nitrogen ratio (C/N) of 200 in a batch culture, the highest biomass production was 4.35g/L, with a lipid content of 48.2%. At acetic acid concentrations as low as 4g/L, a sequencing batch culture (SBC) with a C/N of 100 increased biomass production to 4.21g/L, with a lipid content of 38.6%. These results provide usable culture strategies for lipid production by R. toruloides AS 2.1389 when using diverse waste-derived volatile fatty acids. PMID:26851898

  4. Prolonged acid rain facilitates soil organic carbon accumulation in a mature forest in Southern China.

    PubMed

    Wu, Jianping; Liang, Guohua; Hui, Dafeng; Deng, Qi; Xiong, Xin; Qiu, Qingyan; Liu, Juxiu; Chu, Guowei; Zhou, Guoyi; Zhang, Deqiang

    2016-02-15

    With the continuing increase in anthropogenic activities, acid rain remains a serious environmental threat, especially in the fast developing areas such as southern China. To detect how prolonged deposition of acid rain would influence soil organic carbon accumulation in mature subtropical forests, we conducted a field experiment with simulated acid rain (SAR) treatments in a monsoon evergreen broadleaf forest at Dinghushan National Nature Reserve in southern China. Four levels of SAR treatments were set by irrigating plants with water of different pH values: CK (the control, local lake water, pH ≈ 4.5), T1 (water pH=4.0), T2 (water pH=3.5), and T3 (water pH=3.0). Results showed reduced pH measurements in the topsoil exposed to simulated acid rains due to soil acidification. Soil respiration, soil microbial biomass and litter decomposition rates were significantly decreased by the SAR treatments. As a result, T3 treatment significantly increased the total organic carbon by 24.5% in the topsoil compared to the control. Furthermore, surface soil became more stable as more recalcitrant organic matter was generated under the SAR treatments. Our results suggest that prolonged acid rain exposure may have the potential to facilitate soil organic carbon accumulation in the subtropical forest in southern China. PMID:26657252

  5. [Studies on carbonization of saccharides by using aqueous solution of various acids].

    PubMed

    Zhang, Xin; He, An-Qi; Kang, Ting-Guo; Xia, Jin-Ming; Weng, Shi-Fu; Xu, Yi-Zhuang; Wu, Jin-Guang

    2014-09-01

    The authors tried to establish an approach to use acids to convert biomass into a fuel with higher carbon content and lower oxygen content in a zero-energy-consumption fashion. Considering that biomass is composed of monosaccharide, we used aqueous solutions of variation acids including hydrochloric acid, sulfuric acid and perchloric acid to treat 2-deoxy-ribose and fructose at ambient temperature and pressure. Black substances were produced after a period of time when 2-deoxy-ribose and fructose were mixed with aqueous solutions containing 8 mol · L(-1) acids. The black substance was collected and characterized by using elemental analysis, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Elemental analysis results indicate that the contents of carbon increases significantly in the black substances in comparison with 2-deoxy-ribose and fructose. Moreover, XPS results indicate that the content of oxygen in the black substance undergoes a significant decrease compared with pure 2-deoxy-ribose and fructose. In the XPS spectra, the is peaks of 2-deoxy-ribose, strong sub peak at 286. 05 eV, which is assigned to carbon linked to oxygen directly, dominate in the C is peak envelop. After treatment by HClO4, the peak decreased dramatically. This result also supports the conclusion that the content of oxygen in mono-saccharide is significantly reduced after treatment by acids. In the FTIR spectra of the black substances, strong peaks can be observed around 1 600 cm(-1), indicating that C==C bond is formed in the product. The above results suggest that treatments with acids may be developed as a new zero-energy-consumption approach to convert biomass in a new fuel with improved energy output efficiency. PMID:25532323

  6. Controlled exposures of volunteers to respirable carbon and sulfuric acid aerosols

    SciTech Connect

    Anderson, K.R.; Avol, E.L.; Edwards, S.A.; Shamoo, D.A.; Ruchuan Peng; Linn, W.S.; Hackney, J.D. )

    1992-06-01

    Respirable carbon or fly ash particles are suspected to increase the respiratory toxicity of coexisting acidic air pollutants, by concentrating acid on their surfaces and so delivering it efficiently to the lower respiratory tract. To investigate this issue, the authors exposed 15 healthy and 15 asthmatic volunteers in a controlled-environment chamber to four test atmospheres: (1) clean air; (2) 0.5-{mu}m H{sub 2}SO{sub 4} aerosol at {approx}100 {mu}g/m{sup 3}, generated from water solution; (3) 0.5-{mu}m carbon aerosol at {approx}250 {mu}g/m{sup 3}, generated from highly pure carbon black with specific surface area comparable to ambient pollution particles; and (4) carbon as in (3) plus {approx}100 {mu}g/m{sup 3} of ultrafine H{sub 2}SO{sub 4} aerosol generated from fuming sulfuric acid. Electron microscopy showed that nearly all acid in (4) became attached to carbon particle surfaces, and that most particles remained in the sub-{mu}m size range. Exposures were performed double-blind, 1 week apart. They lasted 1 hr each, with alternate 10-min periods of heavy exercise (ventilation {approx}50 L/min) and rest. Subjects gargled citrus juice before exposure to suppress airway ammonia. Lung function and symptoms were measured pre-exposure, after initial exercise, and at end-exposure. Bronchial reactivity to methacholine was measured after exposure. Statistical analyses tested for effects of H{sub 2}SO{sub 4} or carbon, separate or interactive, on health measures.

  7. Carbonate precipitation under bulk acidic conditions as a potential biosignature for searching life on Mars

    NASA Astrophysics Data System (ADS)

    Fernández-Remolar, David C.; Preston, Louisa J.; Sánchez-Román, Mónica; Izawa, Matthew R. M.; Huang, L.; Southam, Gordon; Banerjee, Neil R.; Osinski, Gordon R.; Flemming, Roberta; Gómez-Ortíz, David; Prieto Ballesteros, Olga; Rodríguez, Nuria; Amils, Ricardo; Darby Dyar, M.

    2012-10-01

    Recent observations of carbonate minerals in ancient Martian rocks have been interpreted as evidence for the former presence of circumneutral solutions optimal for carbonate precipitation. Sampling from surface and subsurface regions of the low-pH system of Río Tinto has shown, unexpectedly, that carbonates can form under diverse macroscopic physicochemical conditions ranging from very low to neutral pH (1.5-7.0). A multi-technique approach demonstrates that carbonate minerals are closely associated with microbial activity. Carbonates occur in the form of micron-size carbonate precipitates under bacterial biofilms, mineralization of subsurface colonies, and possible biogenic microstructures including globules, platelets and dumbbell morphologies. We propose that carbonate precipitation in the low-pH environment of Río Tinto is a process enabled by microbially-mediated neutralization driven by the reduction of ferric iron coupled to the oxidation of biomolecules in microbially-maintained circumneutral oases, where the local pH (at the scale of cells or cell colonies) can be much different than in the macroscopic environment. Acidic conditions were likely predominant in vast regions of Mars over the last four billion years of planetary evolution. Ancient Martian microbial life inhabiting low-pH environments could have precipitated carbonates similar to those observed at Río Tinto. Preservation of carbonates at Río Tinto over geologically significant timescales suggests that similarly-formed carbonate minerals could also be preserved on Mars. Such carbonates could soon be observed by the Mars Science Laboratory, and by future missions to the red planet.

  8. Collagen tissue treated with chitosan solutions in carbonic acid for improved biological prosthetic heart valves.

    PubMed

    Gallyamov, Marat O; Chaschin, Ivan S; Khokhlova, Marina A; Grigorev, Timofey E; Bakuleva, Natalia P; Lyutova, Irina G; Kondratenko, Janna E; Badun, Gennadii A; Chernysheva, Maria G; Khokhlov, Alexei R

    2014-04-01

    Calcification of bovine pericardium dramatically shortens typical lifetimes of biological prosthetic heart valves and thus precludes their choice for younger patients. The aim of the present work is to demonstrate that the calcification is to be mitigated by means of treatment of bovine pericardium in solutions of chitosan in carbonic acid, i.e. water saturated with carbon dioxide at high pressure. This acidic aqueous fluid unusually combines antimicrobial properties with absolute biocompatibility as far as at normal pressure it decomposes spontaneously and completely into H2O and CO2. Yet, at high pressures it can protonate and dissolve chitosan materials with different degrees of acetylation (in the range of 16-33%, at least) without any further pretreatment. Even exposure of the bovine pericardium in pure carbonic acid solution without chitosan already favours certain reduction in calcification, somewhat improved mechanical properties, complete biocompatibility and evident antimicrobial activity of the treated collagen tissue. The reason may be due to high extraction ability of this peculiar compressed fluidic mixture. Moreover, exposure of the bovine pericardium in solutions of chitosan in carbonic acid introduces even better mechanical properties and highly pronounced antimicrobial activity of the modified collagen tissue against adherence and biofilm formation of relevant Gram-positive and Gram-negative strains. Yet, the most important achievement is the detected dramatic reduction in calcification for such modified collagen tissues in spite of the fact that the amount of the thus introduced chitosan is rather small (typically ca. 1wt.%), which has been reliably detected using original tritium labelling method. We believe that these improved properties are achieved due to particularly deep and uniform impregnation of the collagen matrix with chitosan from its pressurised solutions in carbonic acid. PMID:24582232

  9. Hydrogen-bond acidic functionalized carbon nanotubes (CNTs) with covalently-bound hexafluoroisopropanol groups

    SciTech Connect

    Fifield, Leonard S.; Grate, Jay W.

    2010-06-01

    Fluorinated hydrogen-bond acidic groups are directly attached to the backbone of single walled carbon nanotubes (SWCNTs) without the introduction of intermediate electron donating surface groups. Hexafluoroalcohol functional groups are exceptionally strong hydrogen bond acids, and are added to the nanotube surface using the aryl diazonium approach to create hydrogen-bond acidic carbon nanotube (CNT) surfaces. These groups can promote strong hydrogen-bonding interactions with matrix materials in composites or with molecular species to be concentrated and sensed. In the latter case, this newly developed material is expected to find useful application in chemical sensors and in CNT-based preconcentrator devices for the detection of pesticides, chemical warfare agents and explosives.

  10. Surface and crustal expression of ocean subduction retreat vs delamination (sub-crustal retreat): Implications for the Apennines tectonics

    NASA Astrophysics Data System (ADS)

    Göğüş, Oğuz H.; Chiarabba, Claudio; Pysklywec, Russell; Faccenna, Claudio; Husson, Laurent

    2015-04-01

    Many geological and geophysical observations in the Mediterranean (Apennines-Tyrrhenian, Betic/Rif -Alboran, and the Hellenic-Aegean) orogenic belts postulate that syn-convergent extension may be a common geological processs in response to deep slab-mantle interactions. Two primary geodynamic processes have been suggested for the onset of lithospheric scale extension that occurs contemporaneous with shortening: (1) retreating ocean subduction with significant overriding plate extension/thinning (e.g back-arc basin formations); and (2) inferred post-collisional lithospheric delamination (sub-crustal retreat) following subduction retreat. In a series of computational geodynamic experiments, we quantitatively investigate the surface and crustal response to these two deep lithospheric thinning/removal mechanisms, identified by transient surface tectonics. Surface topography associated with retreating ocean subduction indicates a broad region of surface subsidence leading to the formation back-arc basin. Models of lithospheric delamination predict initially elevated surface topography due to hot mantle upwelling (after removal) then more localized surface depression with crustal weakening and gravitational collapse. In both retreat and delamination models, maximum surface subsidence occurs in response to the subduction/delamination slab mobilization but the delamination process may develop more rapidly depending on the weakness of the lower crust. The delamination hinge/subduction trench is associated with crustal shortening and extension/thinning in the "back-arc zone" due to the retro-ward motion of the hinge, although calculated stretching factors (β) are higher in delamination experiments. The thermal expression of extending back-arc zone in delamination experiments is dominated by significant thermal perturbation of the crust caused by the underlying sub-lithospheric mantle flow. With subduction retreat experiments, the amount of crustal heating is dependent on

  11. Maintenance carbon cycle in crassulacean Acid metabolism plant leaves : source and compartmentation of carbon for nocturnal malate synthesis.

    PubMed

    Kenyon, W H; Severson, R F; Black, C C

    1985-01-01

    The reciprocal relationship between diurnal changes in organic acid and storage carbohydrate was examined in the leaves of three Crassulacean acid metabolism plants. It was found that depletion of leaf hexoses at night was sufficient to account quantitatively for increase in malate in Ananas comosus but not in Sedum telephium or Kalanchoë daigremontiana. Fructose and to a lesser extent glucose underwent the largest changes. Glucose levels in S. telephium leaves oscillated diurnally but were not reciprocally related to malate fluctuations.Analysis of isolated protoplasts and vacuoles from leaves of A. comosus and S. telephium revealed that vacuoles contain a large percentage (>50%) of the protoplast glucose, fructose and malate, citrate, isocitrate, ascorbate and succinate. Sucrose, a major constituent of intact leaves, was not detectable or was at extremely low levels in protoplasts and vacuoles from both plants.In isolated vacuoles from both A. comosus and S. telephium, hexose levels decreased at night at the same time malate increased. Only in A. comosus, however, could hexose metabolism account for a significant amount of the nocturnal increase in malate. We conclude that, in A. comosus, soluble sugars are part of the daily maintenance carbon cycle and that the vacuole plays a dynamic role in the diurnal carbon assimilation cycle of this Crassulacean acid metabolism plant. PMID:16664005

  12. Facile Carbon Fixation to Performic Acids by Water-Sealed Dielectric Barrier Discharge.

    PubMed

    Kawasaki, Mitsuo; Morita, Tatsuo; Tachibana, Kunihide

    2015-01-01

    Carbon fixation refers to the conversion of carbon dioxide (CO2) to organic materials, as commonly performed in nature through photosynthesis by plants and other autotrophic organisms. The creation of artificial carbon fixation processes is one of the greatest challenges for chemistry to solve the critical environmental issue concerning the reduction of CO2 emissions. We have developed an electricity-driven facile CO2 fixation process that yields performic acid, HCO2OH, from CO2 and water at neutral pH by dielectric barrier discharge with an input electric power conversion efficiency of currently 0.2-0.4%. This method offers a promising future technology for artificial carbon fixation on its own, and may also be scaled up in combination with e.g., the post-combustion CO2 capture and storage technology. PMID:26439402

  13. Facile Carbon Fixation to Performic Acids by Water-Sealed Dielectric Barrier Discharge

    NASA Astrophysics Data System (ADS)

    Kawasaki, Mitsuo; Morita, Tatsuo; Tachibana, Kunihide

    2015-10-01

    Carbon fixation refers to the conversion of carbon dioxide (CO2) to organic materials, as commonly performed in nature through photosynthesis by plants and other autotrophic organisms. The creation of artificial carbon fixation processes is one of the greatest challenges for chemistry to solve the critical environmental issue concerning the reduction of CO2 emissions. We have developed an electricity-driven facile CO2 fixation process that yields performic acid, HCO2OH, from CO2 and water at neutral pH by dielectric barrier discharge with an input electric power conversion efficiency of currently 0.2-0.4%. This method offers a promising future technology for artificial carbon fixation on its own, and may also be scaled up in combination with e.g., the post-combustion CO2 capture and storage technology.

  14. Facile Carbon Fixation to Performic Acids by Water-Sealed Dielectric Barrier Discharge

    PubMed Central

    Kawasaki, Mitsuo; Morita, Tatsuo; Tachibana, Kunihide

    2015-01-01

    Carbon fixation refers to the conversion of carbon dioxide (CO2) to organic materials, as commonly performed in nature through photosynthesis by plants and other autotrophic organisms. The creation of artificial carbon fixation processes is one of the greatest challenges for chemistry to solve the critical environmental issue concerning the reduction of CO2 emissions. We have developed an electricity-driven facile CO2 fixation process that yields performic acid, HCO2OH, from CO2 and water at neutral pH by dielectric barrier discharge with an input electric power conversion efficiency of currently 0.2−0.4%. This method offers a promising future technology for artificial carbon fixation on its own, and may also be scaled up in combination with e.g., the post-combustion CO2 capture and storage technology. PMID:26439402

  15. Aqueous solutions of acidic ionic liquids for enhanced stability of polyoxometalate-carbon supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Hu, Chenchen; Zhao, Enbo; Nitta, Naoki; Magasinski, Alexandre; Berdichevsky, Gene; Yushin, Gleb

    2016-09-01

    Nanocomposites based on polyoxometalates (POMs) nanoconfined in microporous carbons have been synthesized and used as electrodes for supercapacitors. The addition of the pseudocapacitance from highly reversible redox reaction of POMs to the electric double-layer capacitance of carbon lead to an increase in specific capacitance of ∼90% at 1 mV s-1. However, high solubility of POM in traditional aqueous electrolytes leads to rapid capacity fading. Here we demonstrate that the use of aqueous solutions of protic ionic liquids (P-IL) as electrolyte instead of aqueous sulfuric acid solutions offers an opportunity to significantly improve POM cycling stability. Virtually no degradation in capacitance was observed in POM-based positive electrode after 10,000 cycles in an asymmetric capacitor with P-IL aqueous electrolyte. As such, POM-based carbon composites may now present a viable solution for enhancing energy density of electrical double layer capacitors (EDLC) based on pure carbon electrodes.

  16. Neutralizing Carbonic Acid in Deep Carbonate Strata below the North Atlantic

    SciTech Connect

    Daniel P. Schrag

    2006-07-14

    Our research is aimed at investigating several technical issues associated with carbon dioxide sequestration in calcium carbonate sediments below the sea floor through laboratory experiments and chemical transport modeling. Our goal is to evaluate the basic feasibility of this approach, including an assessment of optimal depths, sediment types, and other issues related to site selection. The results of our modeling efforts were published this past summer in the Proceedings of the National Academy of Sciences. We are expanding on that work through a variety of laboratory and modeling efforts. In the laboratories at Columbia and at Harvard, we are studying the flow of liquid carbon dioxide and carbon dioxide-water mixtures through calcium carbonate sediments to better understand the geomechanical and structural stability of the sediments during and after injection. We are currently preparing the results of these findings for publication. In addition, we are investigating the kinetics of calcium carbonate dissolution in the presence of CO{sub 2}-water fluids, which is a critical feature of the system as it allows for increased permeability during injection. We are also investigating the possibility of carbon dioxide hydrate formation in the pore fluid, which might complicate the injection procedure by reducing sediment permeability but might also provide an upper seal in the sediment-pore fluid system, preventing release of CO{sub 2} into the deep ocean, particularly if depth and temperature at the injection point rule out immediate hydrate formation. This is done by injecting liquid CO{sub 2} into various types of porous media, and then monitoring the changes in permeability. Finally, we are performing an economic analysis to estimate costs of drilling and gas injection, site monitoring as well as the availability of potential disposal sites with particular emphasis on those sites that are within the 200-mile economic zone of the United States. We present some

  17. Analysis of the stable carbon isotope composition of formic and acetic acids.

    PubMed

    Lee, Xinqing; Zhang, Like; Huang, Daikuan; An, Ning; Yang, Fang; Jiang, Wei; Fang, Bin

    2013-05-15

    Formic and acetic acids are ubiquitous in the environment and in many biological processes. Analysis of the stable carbon isotope composition (δ(13)C) of formic and acetic acids is important to understanding their biogeochemical cycles. However, it has been faced with poor accuracy and high detection limits due to their low carbon number, high hydrophilicity, and semi-volatility. Here we developed an analytical technique by needle trap and gas chromatography-isotope ratio mass spectrometry (GC-IRMS). The organic acids in aqueous solution were extracted using a NeedlEx needle through purge-and-trap and were analyzed by GC-IRMS for δ(13)C. The procedures incur no isotope fractionation. Defined as the point at which the mean δ(13)C is statistically the same as the given value and the analytical error starts rising, the method's detection limits are 200 and 100 mg/L for formic and acetic acids, respectively, with an uncertainty of approximately 0.5‰ in direct extraction and analysis. They were lowered to 1 mg/L with precision of 0.9‰ after samples were subjected to preconcentration. The method was successfully applied to natural samples as diverse as precipitation, vinegars, ant plasma, and vehicle exhaust, which vary considerably in concentration and matrix of the organic acids. It is applicable to the organic acids in not only aqueous solution but also gaseous phase. PMID:23395975

  18. The effect of spiritual retreat on nurses' spirituality: a randomized controlled study.

    PubMed

    Bay, Paul S; Ivy, Steven S; Terry, Colin L

    2010-01-01

    This study tested whether two 1-day retreats focused on spiritual self-care would positively change nurse participants' spirituality. A total of 199 critical care nurses were accepted into this study; 87 were randomized to receive the retreat intervention. All 199 nurses were tested preretreat, 1 month and 6 months postretreat. Retreat participants demonstrated increased spirituality. PMID:20421752

  19. [Effects of simulated acid rain on decomposition of soil organic carbon and crop straw].

    PubMed

    Zhu, Xue-Zhu; Huang, Yao; Yang, Xin-Zhong

    2009-02-01

    To evaluate the effects of acid rain on the organic carbon decomposition in different acidity soils, a 40-day incubation test was conducted with the paddy soils of pH 5.48, 6.70 and 8.18. The soils were amended with 0 and 15 g x kg(-1) of rice straw, adjusted to the moisture content of 400 g x kg(-1) air-dried soil by using simulated rain of pH 6.0, 4.5, and 3.0, and incubated at 20 degrees C. The results showed that straw, acid rain, and soil co-affected the CO2 emission from soil system. The amendment of straw increased the soil CO2 emission rate significantly. Acid rain had no significant effects on soil organic carbon decomposition, but significantly affected the straw decomposition in soil. When treated with pH 3.0 acid rain, the amount of decomposed straw over 40-day incubation in acid (pH 5.48) and alkaline (pH 8.18) soils was 8% higher, while that in neutral soil (pH 6.70) was 15% lower, compared to the treatment of pH 6.0 rain. In the treatment of pH 3.0 acid rain, the decomposition rate of soil organic C in acid (pH 5.48) soil was 43% and 50% (P < 0.05) higher than that in neutral (pH 6.70) and alkaline (pH 8.18) soils, while the decomposition rate of straw in neutral soil was 17% and 16% (P < 0.05) lower than that in acid and alkaline soils, respectively. PMID:19459394

  20. Ancient low-molecular-weight organic acids in permafrost fuel rapid carbon dioxide production upon thaw.

    PubMed

    Drake, Travis W; Wickland, Kimberly P; Spencer, Robert G M; McKnight, Diane M; Striegl, Robert G

    2015-11-10

    Northern permafrost soils store a vast reservoir of carbon, nearly twice that of the present atmosphere. Current and projected climate warming threatens widespread thaw of these frozen, organic carbon (OC)-rich soils. Upon thaw, mobilized permafrost OC in dissolved and particulate forms can enter streams and rivers, which are important processors of OC and conduits for carbon dioxide (CO2) to the atmosphere. Here, we demonstrate that ancient dissolved organic carbon (DOC) leached from 35,800 y B.P. permafrost soils is rapidly mineralized to CO2. During 200-h experiments in a novel high-temporal-resolution bioreactor, DOC concentration decreased by an average of 53%, fueling a more than sevenfold increase in dissolved inorganic carbon (DIC) concentration. Eighty-seven percent of the DOC loss to microbial uptake was derived from the low-molecular-weight (LMW) organic acids acetate and butyrate. To our knowledge, our study is the first to directly quantify high CO2 production rates from permafrost-derived LMW DOC mineralization. The observed DOC loss rates are among the highest reported for permafrost carbon and demonstrate the potential importance of LMW DOC in driving the rapid metabolism of Pleistocene-age permafrost carbon upon thaw and the outgassing of CO2 to the atmosphere by soils and nearby inland waters. PMID:26504243

  1. Ancient low–molecular-weight organic acids in permafrost fuel rapid carbon dioxide production upon thaw

    PubMed Central

    Drake, Travis W.; Wickland, Kimberly P.; Spencer, Robert G. M.; McKnight, Diane M.; Striegl, Robert G.

    2015-01-01

    Northern permafrost soils store a vast reservoir of carbon, nearly twice that of the present atmosphere. Current and projected climate warming threatens widespread thaw of these frozen, organic carbon (OC)-rich soils. Upon thaw, mobilized permafrost OC in dissolved and particulate forms can enter streams and rivers, which are important processors of OC and conduits for carbon dioxide (CO2) to the atmosphere. Here, we demonstrate that ancient dissolved organic carbon (DOC) leached from 35,800 y B.P. permafrost soils is rapidly mineralized to CO2. During 200-h experiments in a novel high–temporal-resolution bioreactor, DOC concentration decreased by an average of 53%, fueling a more than sevenfold increase in dissolved inorganic carbon (DIC) concentration. Eighty-seven percent of the DOC loss to microbial uptake was derived from the low–molecular-weight (LMW) organic acids acetate and butyrate. To our knowledge, our study is the first to directly quantify high CO2 production rates from permafrost-derived LMW DOC mineralization. The observed DOC loss rates are among the highest reported for permafrost carbon and demonstrate the potential importance of LMW DOC in driving the rapid metabolism of Pleistocene-age permafrost carbon upon thaw and the outgassing of CO2 to the atmosphere by soils and nearby inland waters. PMID:26504243

  2. The adsorption of gold, palladium and platinum from acidic chloride solutions on mesoporous carbons.

    SciTech Connect

    Zalupski, Peter R.; McDowell, Rocklan; Dutech, Guy

    2014-08-05

    Studies on the adsorption characteristics of gold, palladium and platinum on mesoporous carbon (CMK-3) and sulfur-impregnated mesoporous carbon (CMK-3/S) evaluated the benefits/drawbacks of the presence of a layer of elemental sulfur inside mesoporous carbon structures. Adsorption isotherms collected for Au(III), Pd(II) and Pt(IV) on those materials suggest that sulfur does enhance the adsorption of those metal ions in mildly acidic environment (pH 3). The isotherms collected in 1 M HCl show that the benefit of sulfur disappears due to the competing influence of large concentration of hydrogen ions on the ion-exchanging mechanism of metal ions sorption on mesoporous carbon surfaces. The collected acid dependencies illustrate similar adsorption characteristics for CMK-3 and CMK-3/S in 1-5 M HCl concentration range. Sorption of metal ions from diluted aqueous acidic mixtures of actual leached electronic waste demonstrated the feasibility of recovery of gold from such liquors.

  3. The adsorption of gold, palladium and platinum from acidic chloride solutions on mesoporous carbons.

    DOE PAGESBeta

    Zalupski, Peter R.; McDowell, Rocklan; Dutech, Guy

    2014-08-05

    Studies on the adsorption characteristics of gold, palladium and platinum on mesoporous carbon (CMK-3) and sulfur-impregnated mesoporous carbon (CMK-3/S) evaluated the benefits/drawbacks of the presence of a layer of elemental sulfur inside mesoporous carbon structures. Adsorption isotherms collected for Au(III), Pd(II) and Pt(IV) on those materials suggest that sulfur does enhance the adsorption of those metal ions in mildly acidic environment (pH 3). The isotherms collected in 1 M HCl show that the benefit of sulfur disappears due to the competing influence of large concentration of hydrogen ions on the ion-exchanging mechanism of metal ions sorption on mesoporous carbon surfaces.more » The collected acid dependencies illustrate similar adsorption characteristics for CMK-3 and CMK-3/S in 1-5 M HCl concentration range. Sorption of metal ions from diluted aqueous acidic mixtures of actual leached electronic waste demonstrated the feasibility of recovery of gold from such liquors.« less

  4. Large discharge capacity from carbon electrodes in sulfuric acid with oxidant

    NASA Astrophysics Data System (ADS)

    Inagaki, M.; Iwashita, N.

    The discharge performance of the graphite intercalation compounds in sulfuric acid containing nitric acid (H 2SO 4-GICs) was studied by focusing on the effects of oxidant and carbon nanotexture. A large discharge capacity from H 2SO 4-GICs synthesized by using an excess amount of HNO 3, more than 150 times of the theoretical value (93 mAh/g carbon), was obtained depending on the amount of oxidant added, the discharge current, and the nanotexture of carbon electrode. The experimental results are explained in terms of competition between the de-intercalation of sulfuric acid due to galvanostatic reduction and the re-intercalation due to chemical oxidation by HN03 during discharging. However, a subsidiary reaction decreases the effective amount of HNO 3 on the discharge by a small current and also on the cycle of chemical charging and electrochemical discharging. The oxidant KMnO 4 gave only a little larger capacity for discharge than the theoretical one, because it was reduced to the manganese oxide precipitates during the oxidation of the carbon electrode.

  5. Fabrication and characterization of polylactic acid and polylactic acid/multi-walled carbon nanotube nanofibers through centrifugal spinning

    NASA Astrophysics Data System (ADS)

    Patlan, Richard

    Biocompatible polymer nanofibers hold great potential in the biomedical engineering field. Their biodegradable nature and enhanced properties could help solve a wide array of health related problems, particularly in the areas of tissue regeneration, drug delivery, and biosensor design. The novel Forcespinning™ method allows the production of submicron fibers without many of the drawbacks found in electrospinning, while also providing a substantial increase in fiber production. The aim of the study was to utilize this method to fabricate non-woven nanofibrous mats composed of polylactic acid (PLA) and polylactic acid/multi-walled carbon nanotube composite fibers. The morphology, thermal properties, and crystalline structure of the resulting nanofibers were then characterized using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), and X-Ray Diffraction (XRD).

  6. Trehalose 6-phosphate coordinates organic and amino acid metabolism with carbon availability.

    PubMed

    Figueroa, Carlos M; Feil, Regina; Ishihara, Hirofumi; Watanabe, Mutsumi; Kölling, Katharina; Krause, Ursula; Höhne, Melanie; Encke, Beatrice; Plaxton, William C; Zeeman, Samuel C; Li, Zhi; Schulze, Waltraud X; Hoefgen, Rainer; Stitt, Mark; Lunn, John E

    2016-02-01

    Trehalose 6-phosphate (Tre6P) is an essential signal metabolite in plants, linking growth and development to carbon metabolism. The sucrose-Tre6P nexus model postulates that Tre6P acts as both a signal and negative feedback regulator of sucrose levels. To test this model, short-term metabolic responses to induced increases in Tre6P levels were investigated in Arabidopsis thaliana plants expressing the Escherichia coli Tre6P synthase gene (otsA) under the control of an ethanol-inducible promoter. Increased Tre6P levels led to a transient decrease in sucrose content, post-translational activation of nitrate reductase and phosphoenolpyruvate carboxylase, and increased levels of organic and amino acids. Radio-isotope ((14)CO2) and stable isotope ((13)CO2) labelling experiments showed no change in the rates of photoassimilate export in plants with elevated Tre6P, but increased labelling of organic acids. We conclude that high Tre6P levels decrease sucrose levels by stimulating nitrate assimilation and anaplerotic synthesis of organic acids, thereby diverting photoassimilates away from sucrose to generate carbon skeletons and fixed nitrogen for amino acid synthesis. These results are consistent with the sucrose-Tre6P nexus model, and implicate Tre6P in coordinating carbon and nitrogen metabolism in plants. PMID:26714615

  7. Trihalomethane formation potential of aquatic and terrestrial fulvic and humic acids: Sorption on activated carbon.

    PubMed

    Abouleish, Mohamed Y Z; Wells, Martha J M

    2015-07-15

    Humic substances (HSs) are precursors for the formation of hazardous disinfection by-products (DBPs) during chlorination of water. Various surrogate parameters have been used to investigate the generation of DBPs by HS precursors and the removal of these precursors by activated carbon treatment. Dissolved organic carbon (DOC)- and ultraviolet absorbance (UVA254)-based isotherms are commonly reported and presumed to be good predictors of the trihalomethane formation potential (THMFP). However, THMFP-based isotherms are rarely published such that the three types of parameters have not been compared directly. Batch equilibrium experiments on activated carbon were used to generate constant-initial-concentration sorption isotherms for well-characterized samples obtained from the International Humic Substances Society (IHSS). HSs representing type (fulvic acid [FA], humic acid [HA]), origin (aquatic, terrestrial), and geographical source (Nordic, Suwannee, Peat, Soil) were examined at pH6 and pH9. THMFP-based isotherms were generated and compared to determine if DOC- and UVA254-based isotherms were good predictors of the THMFP. The sorption process depended on the composition of the HSs and the chemical nature of the activated carbon, both of which were influenced by pH. Activated carbon removal of THM-precursors was pH- and HS-dependent. In some instances, the THMFP existed after UVA254 was depleted. PMID:25847173

  8. Discrete carbon nanotubes increase lead acid battery charge acceptance and performance

    NASA Astrophysics Data System (ADS)

    Swogger, Steven W.; Everill, Paul; Dubey, D. P.; Sugumaran, Nanjan

    2014-09-01

    Performance demands placed upon lead acid batteries have outgrown the technology's ability to deliver. These demands, typically leading to Negative Active Material (NAM) failure, include: short, high-current surges; prolonged, minimal, overvoltage charging; repeated, Ah deficit charging; and frequent deep discharges. Research shows these failure mechanisms are attenuated by inclusion of carbon allotropes into the NAM. Addition of significant quantities of carbon, however, produces detrimental changes in paste rheology, leading to lowered industrial throughput. Additionally, capacity, cold-cranking performance, and other battery metrics are negatively affected at high carbon loads. Presented here is Molecular Rebar® Lead Negative, a new battery additive comprising discrete carbon nanotubes (dCNT) which uniformly disperse within battery pastes during mixing. NS40ZL batteries containing dCNT show enhanced charge acceptance, reserve capacity, and cold-cranking performance, decreased risk of polarization, and no detrimental changes to paste properties, when compared to dCNT-free controls. This work focuses on the dCNT as NAM additives only, but early-stage research is underway to test their functionality as a PAM additive. Batteries infused with Molecular Rebar® Lead Negative address the needs of modern lead acid battery applications, produce none of the detrimental side effects associated with carbon additives, and require no change to existing production lines.

  9. Carbon isotope composition of dissolved humic and fulvic acids in the Tokachi River system.

    PubMed

    Nagao, Seiya; Kodama, Hiroki; Aramaki, Takafumi; Fujitake, Nobuhide; Uchida, Masao; Shibata, Yasuyuki

    2011-07-01

    This study reports carbon isotopic ratios (Δ(14)C and δ(13)C) of dissolved humic and fulvic acids in the Tokachi River system, northern Japan. These acids have a refractory feature and they represent the largest fraction of dissolved organic matter in aquatic environments. The acids were isolated using the XAD extraction method from river water samples collected at three sites (on the upper and lower Tokachi River, and from one of its tributaries) in June 2004 and 2005. δ(13)C values were -27.8 to -26.9 ‰ for humic and fulvic acids. On the other hand, the Δ(14)C values ranged from -247 to +26 ‰ and the average values were -170 ± 79 ‰ for humic acid and -44 ± 73 ‰ for fulvic acid. The difference was attributed to the residence time of fulvic acid in the watershed being shorter than that of humic acid. The large variation suggested that humic substances have a different pathway in each watershed environment. PMID:21515623

  10. Merging photoredox catalysis with Lewis acid catalysis: activation of carbon-carbon triple bonds.

    PubMed

    Jin, Ruiwen; Chen, Yiyong; Liu, Wangsheng; Xu, Dawen; Li, Yawei; Ding, Aishun; Guo, Hao

    2016-08-01

    Here, we demonstrate that merging photoredox catalysis with Lewis acid catalysis provides a fundamentally new activation mode of C-C triple bonds, to achieve the bond-forming reaction of alkynes with weak nucleophiles. Using a synergistic merger of Eosin Y and Cu(OTf)2, a highly efficient cyclization reaction of arene-ynes was developed. PMID:27432542

  11. Colloidal methods for the fabrication of carbon nanotube-manganese dioxide and carbon nanotube-polypyrrole composites using bile acids.

    PubMed

    Ata, M S; Zhitomirsky, I

    2015-09-15

    Nature inspired strategies have been developed for the colloidal processing of advanced composites for supercapacitor applications. New approach was based on the use of commercially available bile acid salts, such as sodium cholate (ChNa) and taurocholic acid sodium salt (TChNa). It was demonstrated that cholic acid (ChH) films can be obtained by electrophoretic deposition (EPD) from ChNa solutions. The analysis of deposition yield, quartz crystal microbalance and cyclic voltammetry data provided an insight into the anodic deposition mechanism. The outstanding suspension stability of multiwalled carbon nanotubes (MWCNT), achieved using bile acids as anionic dispersants, allowed the fabrication of MWCNT films by EPD. The use of ChNa for EPD offered advantages of binding and film forming properties of this material. Composite MnO2-MWCNT films, prepared using ChNa as a dispersant and film forming agent for EPD, showed promising capacitive behavior. In another colloidal strategy, TChNa was used as a dispersant for MWCNT for the fabrication of polypyrrole (PPy) coated MWCNT. The use of PPy coated MWCNT allowed the fabrication of electrodes with high active mass loading, high capacitance and excellent capacitance retention at high charge-discharge rates. PMID:26001135

  12. Effect of magnesium carbonate on the solubility, dissolution and oral bioavailability of fenofibric acid powder as an alkalising solubilizer.

    PubMed

    Kim, Kyeong Soo; Kim, Jeong Hyun; Jin, Sung Giu; Kim, Dong Wuk; Kim, Dong Shik; Kim, Jong Oh; Yong, Chul Soon; Cho, Kwan Hyung; Li, Dong Xun; Woo, Jong Soo; Choi, Han-Gon

    2016-04-01

    To investigate the possibility of developing a novel oral pharmaceutical product using fenofibric acid instead of choline fenofibrate, the powder properties, solubility, dissolution and pharmacokinetics in rats of fenofibrate, choline fenofibrate and fenofibric acid were compared. Furthermore, the effect of magnesium carbonate, an alkalising agent on the solubility, dissolution and oral bioavailability of fenofibric acid was assessed, a mixture of fenofibric acid and magnesium carbonate being prepared by simple blending at a weight ratio of 2/1. The three fenofibrate derivatives showed different particle sizes and melting points with similar crystalline shape. Fenofibric acid had a significantly higher aqueous solubility and dissolution than fenofibrate, but significantly lower solubility and dissolution than choline fenofibrate. However, the fenofibric acid/magnesium carbonate mixture greatly improved the solubility and dissolution of fenofibric acid with an enhancement to levels similar with those for choline fenofibrate. Fenofibric acid gave lower plasma concentrations, AUC and Cmax values compared to choline fenofibrate in rats. However, the mixture resulted in plasma concentrations, AUC and Cmax values levels not significantly different from those for choline fenofibrate. Specifically, magnesium carbonate increased the aqueous solubility, dissolution and bioavailability of fenofibric acid by about 7.5-, 4- and 1.6-fold, respectively. Thus, the mixture of fenofibric acid and magnesium carbonate at the weight ratio of 2/1 might be a candidate for an oral pharmaceutical product with improved oral bioavailability. PMID:26992922

  13. Selective Acidic Leaching of Spent Zinc-Carbon Batteries Followed by Zinc Electrowinning

    NASA Astrophysics Data System (ADS)

    Shalchian, Hossein; Rafsanjani-Abbasi, Ali; Vahdati-Khaki, Jalil; Babakhani, Abolfazl

    2015-02-01

    In this work, a selective acidic leaching procedure was employed for recycling zinc from spent zinc-carbon batteries. Leaching experiments were carried out in order to maximize zinc recovery and minimize manganese recovery in diluted sulfuric acid media. Response surface methodology and analysis of variance were employed for experimental design, data analysis, and leaching optimization. The experimental design has 28 experiments that include 24 main runs and four replicate in center point. The optimal conditions obtained from the selective acidic leaching experiments, were sulfuric acid concentration of 1 pct v/v, leaching temperature of 343 K (70 °C), pulp density of 8 pct w/v, and stirring speed of 300 rpm. The results show that the zinc and manganese recoveries after staged selective leaching are about 92 and 15 pct, respectively. Finally, metallic zinc with purity of 99.9 pct and electrolytic manganese dioxide were obtained by electrowinning.

  14. The erosion of carbonate stone by acid rain: Laboratory and field investigations

    SciTech Connect

    Baedecker, P.A. ); Reddy, M.M. )

    1993-02-01

    This paper describes a laboratory experiment on the effects of acidic deposition on carbonate stone erosion. It can serve as the basis for an undergraduate (or pre college) experiment in environmental chemistry. Recent field investigations are described that provide measurements of carbonate stone dissolution and mechanical erosion under weathering conditions that are prevalent in the eastern US. The purpose of the laboratory work is to answer questions concerning the effects of hydrogen ion deposition on stone erosion processes that were difficult to resolve on the basis of field experiments alone.

  15. Covalently linked deoxyribonucleic acid with multi-walled carbon nanotubes: synthesis and characterization.

    PubMed

    Chen, Weiwei; Yi, Changqing; Chi-Hung, Tzang; Lee, Shuit-Tong; Yang, Mengsu

    2010-01-01

    In this chapter, a multi-step protocol for covalently linking functionalized multi-walled carbon nanotubes (MWCNT) to deoxyribonucleic acid (DNA) oligonucleotides is provided. X-ray photoelectron spectroscopy (XPS) is used to characterize the initially formed amine-terminated MWCNTs, to which DNA is covalently anchored. Atomic force microscopy (AFM) investigation of the DNA-MWCNT conjugates reveals that the chemical functionalization occurs at both the ends and sidewalls of the nanotubes. The described methodology represents an important step toward the realization of DNA-guided self-assembly for carbon nanotubes. PMID:20422378

  16. Microwave-assisted polyol synthesis of carbon nitride dots from folic acid for cell imaging

    PubMed Central

    Guan, Weiwei; Gu, Wei; Ye, Ling; Guo, Chenyang; Su, Su; Xu, Pinxiang; Xue, Ming

    2014-01-01

    A green, one-step microwave-assisted polyol synthesis was employed to prepare blue luminescent carbon nitride dots (CNDs) using folic acid molecules as both carbon and nitrogen sources. The as-prepared CNDs had an average size of around 4.51 nm and could be well dispersed in water. Under excitation at 360 nm, the CNDs exhibited a strong blue luminescence and the quantum yield was estimated to be 18.9%, which is greater than that of other reported CNDs. Moreover, the CNDs showed low cytotoxicity and could efficiently label C6 glioma cells, demonstrating their potential in cell imaging. PMID:25382977

  17. Microwave-assisted polyol synthesis of carbon nitride dots from folic acid for cell imaging.

    PubMed

    Guan, Weiwei; Gu, Wei; Ye, Ling; Guo, Chenyang; Su, Su; Xu, Pinxiang; Xue, Ming

    2014-01-01

    A green, one-step microwave-assisted polyol synthesis was employed to prepare blue luminescent carbon nitride dots (CNDs) using folic acid molecules as both carbon and nitrogen sources. The as-prepared CNDs had an average size of around 4.51 nm and could be well dispersed in water. Under excitation at 360 nm, the CNDs exhibited a strong blue luminescence and the quantum yield was estimated to be 18.9%, which is greater than that of other reported CNDs. Moreover, the CNDs showed low cytotoxicity and could efficiently label C6 glioma cells, demonstrating their potential in cell imaging. PMID:25382977

  18. Extraction of palladium from acidic solutions with the use of carbon adsorbents

    SciTech Connect

    O.N. Kononova; N.G. Goryaeva; N.B. Dostovalova; S.V. Kachin; A.G. Kholmogorov

    2007-08-15

    We studied the sorption of palladium(II) on LKAU-4, LKAU-7, and BAU carbon adsorbents from model hydrochloric acid solutions and the solutions of spent palladium-containing catalysts. It was found that sorbents based on charcoal (BAU) and anthracite (LKAU-4) were characterized by high sorption capacities for palladium. The kinetics of the saturation of carbon adsorbents with palladium(II) ions was studied, and it was found that more than 60% of the initial amount of Pd(II) was recovered in a 1-h contact of an adsorbent with a model solution. This value for the solutions of spent catalysts was higher than 35%.

  19. Carbon disulfide-formic acid: an efficient desorbant for industrial solvents

    SciTech Connect

    Raulinaitis, I.

    1987-11-01

    When vapors of one solvent are collected on a charcoal tube, the desorbants suggested by NIOSH are adequate. When several solvents are collected at the same time, however, then a desorbant suggested for one solvent may mask some of the analytes or some of the analytes may be desorbed very poorly. An actual sample containing 13 solvents was brought to the laboratory for analysis. All solvents could be resolved on a 6-m 10% FFAP column, but some could not be desorbed efficiently with carbon disulfide; masking problems were encountered with other desorbants. Several solvents were tried; the most promising one was carbon disulfide saturated with formic acid.

  20. Pathological organizations and psychic retreats in eating disorders.

    PubMed

    Kadish, Yael Adira

    2012-04-01

    A set of characteristic symptoms allow for the relatively straightforward diagnosis of eating disorders. Simultaneously and paradoxically, underlying the eating disorders are a wide variety of personality organizations/disorders, stretching from the neurotic to the borderline and narcissistic, and even to conditions approaching psychosis. This paper will argue that the inherent commonalities can be ascribed to pathological organizations of a similar nature and quality, operational across the spectrum of eating disorders and functioning in a particular, sadomasochistic way. The typical forms that eating disorders take are based on the specific ways that food and the body are used, that is, symptom manifestation. These distinctive symptom manifestations appear to be related to Steiner's (1982, 1993) notion of a psychic retreat. Pathological organizations and psychic retreats are latent until called upon either sporadically or continuously. When activated, these defensive structures operate like a complex psychic skeleton around which the unique psychodynamics of each patient become rearranged and thereby transformed. PMID:22489814

  1. Biological Response to Recent Pacific Arctic Sea Ice Retreats

    NASA Astrophysics Data System (ADS)

    Grebmeier, Jacqueline M.; Moore, Sue E.; Overland, James E.; Frey, Karen E.; Gradinger, Rolf

    2010-05-01

    Although recent major changes in the physical domain of the Arctic region, such as extreme retreats of summer sea ice since 2007, are well documented, large uncertainties remain regarding responses in the biological domain. In the Pacific Arctic north of Bering Strait, reduction in sea ice extent has been seasonally asymmetric, with minimal changes until the end of June and delayed sea ice formation in late autumn. The effect of extreme ice retreats and seasonal asymmetry in sea ice loss on primary production is uncertain, with no clear shift over time (2003-2008) in satellite-derived chlorophyll concentrations. However, clear changes have occurred during summer in species ranges for zooplankton, bottom-dwelling organisms (benthos), and fish, as well as through the loss of sea ice as habitat and platform for marine mammals.

  2. Optimization of modified carbon paste electrode with multiwalled carbon nanotube/ionic liquid/cauliflower-like gold nanostructures for simultaneous determination of ascorbic acid, dopamine and uric acid.

    PubMed

    Afraz, Ahmadreza; Rafati, Amir Abbas; Najafi, Mojgan

    2014-11-01

    We describe the modification of a carbon paste electrode (CPE) with multiwalled carbon nanotubes (MWCNTs) and an ionic liquid (IL). Electrochemical studies by using a D-optimal mixture design in Design-Expert software revealed an optimized composition of 60% graphite, 14.2% paraffin, 10.8% MWCNT and 15% IL. The optimal modified CPE shows good electrochemical properties that are well matched with model prediction parameters. In the next step, the optimized CPE was modified with gold nanostructures by applying a double-pulse electrochemical technique. The resulting electrode was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and electrochemical impedance spectroscopy. It gives three sharp and well-separated oxidation peaks for ascorbic acid (AA), dopamine (DA), and uric acid (UA). The sensor enables simultaneous determination of AA, DA and UA with linear responses from 0.3 to 285, 0.08 to 200, and 0.1 to 450 μM, respectively, and with 120, 30 and 30 nM detection limits (at an S/N of 3). The method was successfully applied to the determination of AA, DA, and UA in spiked samples of human serum and urine. PMID:25280680

  3. Aegean tectonics: Strain localisation, slab tearing and trench retreat

    NASA Astrophysics Data System (ADS)

    Jolivet, Laurent; Faccenna, Claudio; Huet, Benjamin; Labrousse, Loïc; Le Pourhiet, Laetitia; Lacombe, Olivier; Lecomte, Emmanuel; Burov, Evguenii; Denèle, Yoann; Brun, Jean-Pierre; Philippon, Mélody; Paul, Anne; Salaün, Gwenaëlle; Karabulut, Hayrullah; Piromallo, Claudia; Monié, Patrick; Gueydan, Frédéric; Okay, Aral I.; Oberhänsli, Roland; Pourteau, Amaury; Augier, Romain; Gadenne, Leslie; Driussi, Olivier

    2013-06-01

    We review the geodynamic evolution of the Aegean-Anatolia region and discuss strain localisation there over geological times. From Late Eocene to Present, crustal deformation in the Aegean backarc has localised progressively during slab retreat. Extension started with the formation of the Rhodope Metamorphic Core Complex (Eocene) and migrated to the Cyclades and the northern Menderes Massif (Oligocene and Miocene), accommodated by crustal-scale detachments and a first series of core complexes (MCCs). Extension then localised in Western Turkey, the Corinth Rift and the external Hellenic arc after Messinian times, while the North Anatolian Fault penetrated the Aegean Sea. Through time the direction and style of extension have not changed significantly except in terms of localisation. The contributions of progressive slab retreat and tearing, basal drag, extrusion tectonics and tectonic inheritance are discussed and we favour a model (1) where slab retreat is the main driving engine, (2) successive slab tearing episodes are the main causes of this stepwise strain localisation and (3) the inherited heterogeneity of the crust is a major factor for localising detachments. The continental crust has an inherited strong heterogeneity and crustal-scale contacts such as major thrust planes act as weak zones or as zones of contrast of resistance and viscosity that can localise later deformation. The dynamics of slabs at depth and the asthenospheric flow due to slab retreat also have influence strain localisation in the upper plate. Successive slab ruptures from the Middle Miocene to the Late Miocene have isolated a narrow strip of lithosphere, still attached to the African lithosphere below Crete. The formation of the North Anatolian Fault is partly a consequence of this evolution. The extrusion of Anatolia and the Aegean extension are partly driven from below (asthenospheric flow) and from above (extrusion of a lid of rigid crust).

  4. Climate Change and Glacier Retreat: Scientific Fact and Artistic Opportunity

    NASA Astrophysics Data System (ADS)

    Fagre, D. B.

    2008-12-01

    Mountain glaciers continue to retreat rapidly over most of the globe. In North America, at Glacier National Park, Montana, recent research results from Sperry Glacier (2005-2007) indicate negative mass balances are now 3-4 times greater than in the 1950s. A geospatial model of glacier retreat in the Blackfoot-Jackson basin suggested all glaciers would be gone by 2030 but has proved too conservative. Accelerated glacier shrinkage since the model was developed has mirrored an increase in actual annual temperature that is almost twice the rate used in the model. The glaciers in Glacier National Park are likely to be gone well before 2030. A variety of media, curricula, and educational strategies have been employed to communicate the disappearance of the glaciers as a consequence of global warming. These have included everything from print media and television coverage to podcasts and wayside exhibits along roads in the park. However, a new thrust is to partner with artists to communicate climate change issues to new audiences and through different channels. A scientist-artist retreat was convened to explore the tension between keeping artistic products grounded in factually-based reality while providing for freedom to express artistic creativity. Individual artists and scientists have worked to create aesthetic and emotional images, using painting, poetry, music and photography, to convey core messages from research on mountain ecosystems. Finally, a traveling art exhibit was developed to highlight the photography that systematically documents glacier change through time. The aim was to select photographs that provide the most compelling visual experience for an art-oriented viewer and also accurately reflect the research on glacier retreat. The exhibit opens on January 11, 2009

  5. Scientific Investigators Retreat Brings Like Minds Together | Poster

    Cancer.gov

    Scientists throughout NCI gathered at the 2016 Intramural Scientific Investigators Retreat on Jan. 12, at the Ronald Reagan Building and International Trade Center, to discuss the results of their research with fellow investigators. Several researchers who have made significant advances toward the goal of eliminating the threat of cancer spoke to a packed auditorium of like-minded experts. Speaker topics included the role genetics play in the risk of breast cancer, using fiberglass to...

  6. Methods for estimation of long-term non-carbonate neutralisation of acid rock drainage.

    PubMed

    Miller, Stuart D; Stewart, Warwick S; Rusdinar, Yuni; Schumann, Russell E; Ciccarelli, Joseph M; Li, Jun; Smart, Roger St C

    2010-04-01

    In the long-term phase of an acid rock drainage (ARD) evolution profile, after any short-term neutralisation capacity provided by carbonate minerals is exhausted, the net acid release is a product of a declining acid generation rate (AGR) and a slower, long-term acid neutralisation rate mainly provided by gangue silicate minerals. At some point, the AGR and the non-carbonate acid neutralisation rate (ANRnc) will be similar. Matching of the AGR and ANRnc near 10mg H(2)SO(4)/kg/week is demonstrated in data from 10-year columns. This long-term neutralisation is not measured at present in any accepted assessment tests. Methods to estimate ANRnc, based on silicate mineralogy and solution assays from long-term column leach tests, are compared. Good agreement is demonstrated between rates measured from the solution assay data and those calculated from mineralogy using kinetic databases. More rigorous analysis of the leachate chemistry of selected long-term leach tests also suggests possible cover design criteria based on the maximum AGR that will maintain a pH>4 in leachate from ARD materials. The data show a distinct break at an AGR of 3mg H(2)SO(4)/kg/week, below which no leachate pH is less than 4. The results indicate that an AGR of 10t H(2)SO(4)/ha/year is conservative and a suitable cover design target for ARD control that would be matched by ANRnc. PMID:20097405

  7. Characterization of nano-lead-doped active carbon and its application in lead-acid battery

    NASA Astrophysics Data System (ADS)

    Hong, Bo; Jiang, Liangxing; Xue, Haitao; Liu, Fangyang; Jia, Ming; Li, Jie; Liu, Yexiang

    2014-12-01

    In this paper, nano-lead-doped active carbon (nano-Pb/AC) composite with low hydrogen evolution current for lead-acid battery was prepared by ultrasonic-absorption and chemical-precipitate method. The nano-Pb/AC composite was characterized by SEM, EDS and TEM. The electrochemical characterizations are performed by linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) in a three-electrode system. Since intermediate adsorption is the rate-determining step, the hydrogen evolution reaction (HER) is markedly inhibited as the intermediate adsorption impedance of nano-Pb/AC increased. Meanwhile, the working potential of nano-Pb/AC is widened to the whole potential region of Pb negative plate (from -1.36 V to -0.86 V vs. Hg/HgSO4) in lead-acid battery. In addition, nano-Pb can improve the interfacial compatibility between AC and Pb paste, accordingly relieve the symptoms of carbon floatation. Finally, 2.0 V single-cell flooded lead-acid batteries with 1.0 wt.% nano-Pb/AC or 1.0 wt.% AC addition in negative active materials are assembled. The cell performances test results show that the 3 h rate capacity, quick charging performance, high current discharging performance and cycling performance of nano-Pb/AC modified battery are all improved compared with regular lead-acid battery and AC modified lead-acid battery.

  8. Retreatment Predictions in Odontology by means of CBR Systems.

    PubMed

    Campo, Livia; Aliaga, Ignacio J; De Paz, Juan F; García, Alvaro Enrique; Bajo, Javier; Villarubia, Gabriel; Corchado, Juan M

    2016-01-01

    The field of odontology requires an appropriate adjustment of treatments according to the circumstances of each patient. A follow-up treatment for a patient experiencing problems from a previous procedure such as endodontic therapy, for example, may not necessarily preclude the possibility of extraction. It is therefore necessary to investigate new solutions aimed at analyzing data and, with regard to the given values, determine whether dental retreatment is required. In this work, we present a decision support system which applies the case-based reasoning (CBR) paradigm, specifically designed to predict the practicality of performing or not performing a retreatment. Thus, the system uses previous experiences to provide new predictions, which is completely innovative in the field of odontology. The proposed prediction technique includes an innovative combination of methods that minimizes false negatives to the greatest possible extent. False negatives refer to a prediction favoring a retreatment when in fact it would be ineffective. The combination of methods is performed by applying an optimization problem to reduce incorrect classifications and takes into account different parameters, such as precision, recall, and statistical probabilities. The proposed system was tested in a real environment and the results obtained are promising. PMID:26884749

  9. Retreatment Predictions in Odontology by means of CBR Systems

    PubMed Central

    Campo, Livia; Aliaga, Ignacio J.; García, Alvaro Enrique; Villarubia, Gabriel; Corchado, Juan M.

    2016-01-01

    The field of odontology requires an appropriate adjustment of treatments according to the circumstances of each patient. A follow-up treatment for a patient experiencing problems from a previous procedure such as endodontic therapy, for example, may not necessarily preclude the possibility of extraction. It is therefore necessary to investigate new solutions aimed at analyzing data and, with regard to the given values, determine whether dental retreatment is required. In this work, we present a decision support system which applies the case-based reasoning (CBR) paradigm, specifically designed to predict the practicality of performing or not performing a retreatment. Thus, the system uses previous experiences to provide new predictions, which is completely innovative in the field of odontology. The proposed prediction technique includes an innovative combination of methods that minimizes false negatives to the greatest possible extent. False negatives refer to a prediction favoring a retreatment when in fact it would be ineffective. The combination of methods is performed by applying an optimization problem to reduce incorrect classifications and takes into account different parameters, such as precision, recall, and statistical probabilities. The proposed system was tested in a real environment and the results obtained are promising. PMID:26884749

  10. Carbon quantum dots with photo-generated proton property as efficient visible light controlled acid catalyst

    NASA Astrophysics Data System (ADS)

    Li, Haitao; Liu, Ruihua; Kong, Weiqian; Liu, Juan; Liu, Yang; Zhou, Lei; Zhang, Xing; Lee, Shuit-Tong; Kang, Zhenhui

    2013-12-01

    Developing light-driven acid catalyst will be very meaningful for the controlled-acid catalytic processes towards a green chemical industry. Here, based on scanning electrochemical microscopy (SECM) and ΔpH testing, we demonstrate that the 5-10 nm carbon quantum dots (CQDs) synthesized by electrochemical ablation of graphite have strong light-induced proton properties under visible light in solution, which can be used as an acid catalyst. The 5-10 nm CQDs' catalytic activity is strongly dependent on the illumination intensity and the temperature of the reaction system. As an effective visible light driven and controlled acid-catalyst, 5-10 nm CQDs can catalyze a series of organic reactions (esterification, Beckmann rearrangement and aldol condensation) with high conversion (34.7-46.2%, respectively) in water solution under visible light, while the 1-4 nm CQDs and 10-2000 nm graphite do not have such excellent catalytic activity. The use of 5-10 nm CQDs as a light responsive and controllable photocatalyst is truly a novel application of carbon-based nanomaterials, which may significantly push research in the current catalytic industry, environmental pollution and energy issues.Developing light-driven acid catalyst will be very meaningful for the controlled-acid catalytic processes towards a green chemical industry. Here, based on scanning electrochemical microscopy (SECM) and ΔpH testing, we demonstrate that the 5-10 nm carbon quantum dots (CQDs) synthesized by electrochemical ablation of graphite have strong light-induced proton properties under visible light in solution, which can be used as an acid catalyst. The 5-10 nm CQDs' catalytic activity is strongly dependent on the illumination intensity and the temperature of the reaction system. As an effective visible light driven and controlled acid-catalyst, 5-10 nm CQDs can catalyze a series of organic reactions (esterification, Beckmann rearrangement and aldol condensation) with high conversion (34