Simultaneous bond degradation and bond formation during phenol-formaldehyde curing with wood

Science.gov (United States)

Daniel J. Yelle; John Ralph

2016-01-01

Bonding of wood using phenol–formaldehyde adhesive develops highly durable bonds. Phenol– formaldehyde is believed to form primary bonds with wood cell wall polymers (e.g., lignin). However, it is unclear how this adhesive interacts and bonds to lignin. Through wood solubilisation methodologies, earlywood and latewood bonded assemblies were characterized using two-...

Modelling sea ice formation in the Terra Nova Bay polynya

Science.gov (United States)

Sansiviero, M.; Morales Maqueda, M. Á.; Fusco, G.; Aulicino, G.; Flocco, D.; Budillon, G.

2017-02-01

Antarctic sea ice is constantly exported from the shore by strong near surface winds that open leads and large polynyas in the pack ice. The latter, known as wind-driven polynyas, are responsible for significant water mass modification due to the high salt flux into the ocean associated with enhanced ice growth. In this article, we focus on the wind-driven Terra Nova Bay (TNB) polynya, in the western Ross Sea. Brine rejected during sea ice formation processes that occur in the TNB polynya densifies the water column leading to the formation of the most characteristic water mass of the Ross Sea, the High Salinity Shelf Water (HSSW). This water mass, in turn, takes part in the formation of Antarctic Bottom Water (AABW), the densest water mass of the world ocean, which plays a major role in the global meridional overturning circulation, thus affecting the global climate system. A simple coupled sea ice-ocean model has been developed to simulate the seasonal cycle of sea ice formation and export within a polynya. The sea ice model accounts for both thermal and mechanical ice processes. The oceanic circulation is described by a one-and-a-half layer, reduced gravity model. The domain resolution is 1 km × 1 km, which is sufficient to represent the salient features of the coastline geometry, notably the Drygalski Ice Tongue. The model is forced by a combination of Era Interim reanalysis and in-situ data from automatic weather stations, and also by a climatological oceanic dataset developed from in situ hydrographic observations. The sensitivity of the polynya to the atmospheric forcing is well reproduced by the model when atmospheric in situ measurements are combined with reanalysis data. Merging the two datasets allows us to capture in detail the strength and the spatial distribution of the katabatic winds that often drive the opening of the polynya. The model resolves fairly accurately the sea ice drift and sea ice production rates in the TNB polynya, leading to

Ketene Formation in Interstellar Ices: A Laboratory Study

Science.gov (United States)

Hudson, Reggie L.; Loeffler, Mark Josiah

2013-01-01

The formation of ketene (H2CCO, ethenone) in polar and apolar ices was studied with in situ 0.8 MeV proton irradiation, far-UVphotolysis, and infrared spectroscopic analyses at 10-20 K. Using isotopically enriched reagents, unequivocal evidencewas obtained for ketene synthesis in H2O-rich and CO2-rich ices, and several reaction products were identified. Results from scavenging experiments suggested that ketene was formed by free-radical pathways, as opposed to acid-base processes or redox reactions. Finally, we use our results to draw conclusions about the formation and stability of ketene in the interstellar medium.

Ice Lens Formation and Frost Heave at the Phoenix Landing Site

Science.gov (United States)

Zent, A. P.; Sizemore, H. G.; Remple, A. W.

2011-01-01

Several lines of evidence indicate that the volume of shallow ground ice in the martian high latitudes exceeds the pore volume of the host regolith. Boynton et al. found an optimal fit to the Mars Odyssey Gamma Ray Spectrometer (GRS) data at the Phoenix landing site by modeling a buried layer of 50-75% ice by mass (up to 90% ice by volume). Thermal and optical observations of recent impact craters in the northern hemisphere have revealed nearly pure ice. Ice deposits containing only 1-2% soil by volume were excavated by Phoenix. The leading hypothesis for the origin of this excess ice is that it developed in situ by a mechanism analogous to the formation of terrestrial ice lenses and needle ice. Problematically, terrestrial soil-ice segregation is driven by freeze/thaw cycling and the movement of bulk water, neither of which are expected to have occurred in the geologically recent past on Mars. If however ice lens formation is possible at temperatures less than 273 K, there are possible implications for the habitability of Mars permafrost, since the same thin films of unfrozen water that lead to ice segregation are used by terrestrial psychrophiles to metabolize and grow down to temperatures of at least 258 K.

Methanol Formation via Oxygen Insertion Chemistry in Ices

Science.gov (United States)

Bergner, Jennifer B.; Öberg, Karin I.; Rajappan, Mahesh

2017-08-01

We present experimental constraints on the insertion of oxygen atoms into methane to form methanol in astrophysical ice analogs. In gas-phase and theoretical studies this process has previously been demonstrated to have a very low or nonexistent energy barrier, but the energetics and mechanisms have not yet been characterized in the solid state. We use a deuterium UV lamp filtered by a sapphire window to selectively dissociate O2 within a mixture of O2:CH4 and observe efficient production of CH3OH via O(1D) insertion. CH3OH growth curves are fit with a kinetic model, and we observe no temperature dependence of the reaction rate constant at temperatures below the oxygen desorption temperature of 25 K. Through an analysis of side products we determine the branching ratio of ice-phase oxygen insertion into CH4: ˜65% of insertions lead to CH3OH, with the remainder leading instead to H2CO formation. There is no evidence for CH3 or OH radical formation, indicating that the fragmentation is not an important channel and that insertions typically lead to increased chemical complexity. CH3OH formation from O2 and CH4 diluted in a CO-dominated ice similarly shows no temperature dependence, consistent with expectations that insertion proceeds with a small or nonexistent barrier. Oxygen insertion chemistry in ices should therefore be efficient under low-temperature ISM-like conditions and could provide an important channel to complex organic molecule formation on grain surfaces in cold interstellar regions such as cloud cores and protoplanetary disk midplanes.

Methanol Formation via Oxygen Insertion Chemistry in Ices

Energy Technology Data Exchange (ETDEWEB)

Bergner, Jennifer B. [Harvard University Department of Chemistry and Chemical Biology, 10 Oxford Street, Cambridge, MA 02138 (United States); Öberg, Karin I.; Rajappan, Mahesh [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2017-08-10

We present experimental constraints on the insertion of oxygen atoms into methane to form methanol in astrophysical ice analogs. In gas-phase and theoretical studies this process has previously been demonstrated to have a very low or nonexistent energy barrier, but the energetics and mechanisms have not yet been characterized in the solid state. We use a deuterium UV lamp filtered by a sapphire window to selectively dissociate O{sub 2} within a mixture of O{sub 2}:CH{sub 4} and observe efficient production of CH{sub 3}OH via O({sup 1}D) insertion. CH{sub 3}OH growth curves are fit with a kinetic model, and we observe no temperature dependence of the reaction rate constant at temperatures below the oxygen desorption temperature of 25 K. Through an analysis of side products we determine the branching ratio of ice-phase oxygen insertion into CH{sub 4}: ∼65% of insertions lead to CH{sub 3}OH, with the remainder leading instead to H{sub 2}CO formation. There is no evidence for CH{sub 3} or OH radical formation, indicating that the fragmentation is not an important channel and that insertions typically lead to increased chemical complexity. CH{sub 3}OH formation from O{sub 2} and CH{sub 4} diluted in a CO-dominated ice similarly shows no temperature dependence, consistent with expectations that insertion proceeds with a small or nonexistent barrier. Oxygen insertion chemistry in ices should therefore be efficient under low-temperature ISM-like conditions and could provide an important channel to complex organic molecule formation on grain surfaces in cold interstellar regions such as cloud cores and protoplanetary disk midplanes.

KETENE FORMATION IN INTERSTELLAR ICES: A LABORATORY STUDY

Energy Technology Data Exchange (ETDEWEB)

Hudson, Reggie L.; Loeffler, Mark J., E-mail: Reggie.Hudson@NASA.gov [Astrochemistry Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2013-08-20

The formation of ketene (H{sub 2}CCO, ethenone) in polar and apolar ices was studied with in situ 0.8 MeV proton irradiation, far-UV photolysis, and infrared spectroscopic analyses at 10-20 K. Using isotopically enriched reagents, unequivocal evidence was obtained for ketene synthesis in H{sub 2}O-rich and CO{sub 2}-rich ices, and several reaction products were identified. Results from scavenging experiments suggested that ketene was formed by free-radical pathways, as opposed to acid-base processes or redox reactions. Finally, we use our results to draw conclusions about the formation and stability of ketene in the interstellar medium.

Implantation of energetic D{sup +} ions into carbon dioxide ices and implications for our solar system: formation of D{sub 2}O and D{sub 2}CO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Bennett, Chris J.; Ennis, Courtney P.; Kaiser, Ralf I., E-mail: ralfk@hawaii.edu [Department of Chemistry, University of Hawai' i at Mānoa, Honolulu, HI 96822 (United States)

2014-10-10

Carbon dioxide (CO{sub 2}) ices were irradiated with energetic D{sup +} ions to simulate the exposure of oxygen-bearing solar system ices to energetic protons from the solar wind and magnetospheric sources. The formation of species was observed online and in situ by exploiting FTIR spectroscopy. Molecular products include ozone (O{sub 3}), carbon oxides (CO{sub 3}(C {sub 2v}, D {sub 3h}), CO{sub 4}, CO{sub 5}, CO{sub 6}), D2-water (D{sub 2}O), and D2-carbonic acid (D{sub 2}CO{sub 3}). Species released into the gas phase were sampled via a quadrupole mass spectrometer, and possible minor contributions from D2-formaldehyde (D{sub 2}CO), D4-methanol (CD{sub 3}OD), and D2-formic acid (DCOOD) were additionally identified. The feasibility of several reaction networks was investigated by determining their ability to fit the observed temporal column densities of 10 key species that were quantified during the irradiation period. Directly relevant to the CO{sub 2}-bearing ices of comets, icy satellites in the outer solar system, and the ice caps on Mars, this work illustrates for the first time that D2-water is formed as a product of the exposure of CO{sub 2} ices to D{sup +} ions. These findings provide strong support for water formation from oxygen-bearing materials via non-thermal hydrogen atoms, and predict reaction pathways that are likely to be unfolding on the surfaces of asteroids and the Moon.

Yields of hydrogen peroxide from the reaction of hydroxyl radical with organic compounds in solution and ice

Directory of Open Access Journals (Sweden)

T. Hullar

2011-07-01

Full Text Available Hydrogen peroxide (HOOH is a significant oxidant in atmospheric condensed phases (e.g., cloud and fog drops, aqueous particles, and snow that also photolyzes to form hydroxyl radical (^•OH. ^•OH can react with organics in aqueous phases to form organic peroxyl radicals and ultimately reform HOOH, but the efficiency of this process in atmospheric aqueous phases, as well as snow and ice, is not well understood. We investigate HOOH formation from ^•OH attack on 10 environmentally relevant organic compounds: formaldehyde, formate, glycine, phenylalanine, benzoic acid, octanol, octanal, octanoic acid, octanedioic acid, and 2-butoxyethanol. Liquid and ice samples with and without nitrate (as an ^•OH source were illuminated using simulated solar light, and HOOH formation rates were measured as a function of pH and temperature. For most compounds, the formation rate of HOOH without nitrate was the same as the background formation rate in blank water (i.e., illumination of the organic species does not produce HOOH directly, while formation rates with nitrate were greater than the water control (i.e., reaction of ^•OH with the organic species forms HOOH. Yields of HOOH, defined as the rate of HOOH production divided by the rate of ^•OH production, ranged from essentially zero (glycine to 0.24 (octanal, with an average of 0.12 ± 0.05 (95 % CI. HOOH production rates and yields were higher at lower pH values. There was no temperature dependence of the HOOH yield for formaldehyde or octanedioic acid between −5 to 20 °C and ice samples had approximately the same HOOH yield as the aqueous solutions. In contrast, HOOH yields in formate solutions were higher at 5 and 10 °C compared to −5 and 20 °C. Yields of HOOH in ice for solutions containing nitrate and either phenylalanine, benzoate, octanal, or octanoic acid were indistinguishable from zero. Our HOOH yields were approximately

Calculation of kinetic parameters of amino-formaldehyde polymers formation in the presence of calcium ions

Directory of Open Access Journals (Sweden)

V.V. Arhipova

2016-05-01

Full Text Available Calcium carbonate is on of widely used fillers of composite materials. The area of its application depend on disperse structure, particle shape and other. The modification of calcium carbonate by high-molecular polymers allows changing its characteristics and surface properties in a wide range. The modification of calcium carbonate often carried out with use of amino-formaldehyde polymers (AFP. Aim: The aim of this work is to determine the kinetic characteristics of amino-formaldehyde polymers polycondensation process in the presence of calcium ions. Materials and Methods: The mechanism of AFP polycondensation is complex and depends on various factors. Polycondensation of AFP took place under following conditions: the temperature is 20, 30, 60°C; the molar ratio of carbamide to formaldehyde is 1:1.25; the polycondensation duration is 2 hours; the mass ratio of CaCO3:AFP = 1:1. The polycondensation process was carried out in calcium chloride solution with рН=2…5.5. The concentration of formaldehyde and metilol groups determined during the experiment using chemical titrimetric method. Results: It is shown that polycondensation process of AFP in the presence of Сa2+ ions at their concentration from 0 to 2,25 mol/l (0…90 g/l leads to acceleration of process more than by 1.8 times at temperature of 20°C. Further increase of Сa2+ concentration leads to reduction of process speed. At temperature of 30°C the speed of process almost does not change in the range of Сa2+ concentration from 0 to 2,25 mol/l and further decreases slightly. For all range of Сa2+ concentration at temperature of 60°C the reduction of process speed is observed. Influence of Сa2+ on process of polycondensation confirms assumption made earlier of formation of weak bonds between AFP and calcium ions which at low temperatures interfere with hydrolysis of methyleneurea and collapse at increasing of process temperature.

A kinetic study of the formation of organic solids from formaldehyde: Implications for the origin of extraterrestrial organic solids in primitive Solar System objects

Science.gov (United States)

Kebukawa, Yoko; Cody, George D.

2015-03-01

Aqueous organic solid formation from formaldehyde via the formose reaction and subsequent reactions is a possible candidate for the origin of complex primitive chondritic insoluble organic matter (IOM) and refractory carbon in comets. The rate of formation of organic solids from formaldehyde was studied as a function of temperature and time, with and without ammonia, in order to derive kinetic expressions for polymer yield. The evolution in molecular structure as a function of time and temperature was studied using infrared spectroscopy. Using these kinetic expressions, the yield of organic solids is estimated for extended time and temperature ranges. For example, the half-life for organic solid formation is ∼5 days at 373 K, ∼200 days at 323 K, and ∼70 years at 273 K with ammonia, and ∼25 days at 373 K, ∼13 years at 323 K, and ∼2 × 104 years at 273 K without ammonia. These results indicate that organic solids could form during the aqueous alteration in meteorite parent bodies. If liquid water existed early in the interiors of Kuiper belt objects (KBOs), formaldehyde could convert into organic solids at temperatures close to 273 K, and possibly even below 273 K in the ammonia-water system.

Ice-lens formation and geometrical supercooling in soils and other colloidal materials

KAUST Repository

Style, Robert W.

2011-10-14

We present a physically intuitive model of ice-lens formation and growth during the freezing of soils and other dense, particulate suspensions. Motivated by experimental evidence, we consider the growth of an ice-filled crack in a freezing soil. At low temperatures, ice in the crack exerts large pressures on the crack walls that will eventually cause the crack to split open. We show that the crack will then propagate across the soil to form a new lens. The process is controlled by two factors: the cohesion of the soil and the geometrical supercooling of the water in the soil, a new concept introduced to measure the energy available to form a new ice lens. When the supercooling exceeds a critical amount (proportional to the cohesive strength of the soil) a new ice lens forms. This condition for ice-lens formation and growth does not appeal to any ad hoc, empirical assumptions, and explains how periodic ice lenses can form with or without the presence of a frozen fringe. The proposed mechanism is in good agreement with experiments, in particular explaining ice-lens pattern formation and surges in heave rate associated with the growth of new lenses. Importantly for systems with no frozen fringe, ice-lens formation and frost heave can be predicted given only the unfrozen properties of the soil. We use our theory to estimate ice-lens growth temperatures obtaining quantitative agreement with the limited experimental data that are currently available. Finally we suggest experiments that might be performed in order to verify this theory in more detail. The theory is generalizable to complex natural-soil scenarios and should therefore be useful in the prediction of macroscopic frost-heave rates. © 2011 American Physical Society.

Influence of Sea Ice Crack Formation on the Spatial Distribution of Nutrients and Microalgae in Flooded Antarctic Multiyear Ice

Science.gov (United States)

Nomura, Daiki; Aoki, Shigeru; Simizu, Daisuke; Iida, Takahiro

2018-02-01

Cracks are common and natural features of sea ice formed in the polar oceans. In this study, a sea ice crack in flooded, multiyear, land-fast Antarctic sea ice was examined to assess its influence on biological productivity and the transport of nutrients and microalgae into the upper layers of neighboring sea ice. The water inside the crack and the surrounding host ice were characterized by a strong discoloration (brown color), an indicator of a massive algal bloom. Salinity and oxygen isotopic ratio measurements indicated that 64-84% of the crack water consisted of snow meltwater supplied during the melt season. Measurements of nutrient and chlorophyll a concentrations within the slush layer pool (the flooded layer at the snow-ice interface) revealed the intrusion of water from the crack, likely forced by mixing with underlying seawater during the tidal cycle. Our results suggest that sea ice crack formation provides conditions favorable for algal blooms by directly exposing the crack water to sunlight and supplying nutrients from the under-ice water. Subsequently, constituents of the crack water modified by biological activity were transported into the upper layer of the flooded sea ice. They were then preserved in the multiyear ice column formed by upward growth of sea ice caused by snow ice formation in areas of significant snow accumulation.

Changes in the composition and bioavailability of dissolved organic matter during sea ice formation

DEFF Research Database (Denmark)

Jørgensen, Linda; Stedmon, Colin A.; Kaartokallio, Hermanni

2015-01-01

matter (FDOM) fractions in sea ice, brines (contained in small pores between the ice crystals), and the underlying seawater during a 14 d experiment. Two series of mesocosms were used: one with seawater alone and one with seawater enriched with humic-rich river water. Abiotic processes increased...... processes such as sea ice formation as the source of the significant DOM removal in the Arctic Ocean. We present the results of a mesocosm experiment designed to investigate how sea ice formation affects DOM composition and bioavailability. We measured the change in different fluorescent dissolved organic...... the humic-like FDOM signal in the seawater below the ice during the initial ice formation. Humic-like FDOM fractions with a marine signal were preferentially retained in sea ice (relative to salinity), whereas humic-like FDOM with a terrestrial signal behaved more conservatively with respect to salinity...

On Positronium Formation in Crystalline and Amorphous Ice at Low Positron Energy

DEFF Research Database (Denmark)

Mogensen, O. E.

1986-01-01

The positronium (Ps) yield for ice, measured by Eldrup et al. using a low-energy positron beam, is discussed in terms of the spur model of Ps formation. The pronounced maxima in the Ps yield for crystalline ice at positron energies below 65 eV are well explained by effects due to energy conservat......The positronium (Ps) yield for ice, measured by Eldrup et al. using a low-energy positron beam, is discussed in terms of the spur model of Ps formation. The pronounced maxima in the Ps yield for crystalline ice at positron energies below 65 eV are well explained by effects due to energy...

Parametric studies of contrail ice particle formation in jet regime using microphysical parcel modeling

Directory of Open Access Journals (Sweden)

H.-W. Wong

2010-04-01

Full Text Available Condensation trails (contrails formed from water vapor emissions behind aircraft engines are the most uncertain components of the aviation impacts on climate change. To gain improved knowledge of contrail and contrail-induced cirrus cloud formation, understanding of contrail ice particle formation immediately after aircraft engines is needed. Despite many efforts spent in modeling the microphysics of ice crystal formation in jet regime (with a plume age <5 s, systematic understanding of parametric effects of variables affecting contrail ice particle formation is still limited. In this work, we apply a microphysical parcel modeling approach to study contrail ice particle formation in near-field aircraft plumes up to 1000 m downstream of an aircraft engine in the soot-rich regime (soot number emission index >1×10¹⁵ (kg-fuel⁻¹ at cruise. The effects of dilution history, ion-mediated nucleation, ambient relative humidity, fuel sulfur contents, and initial soot emissions were investigated. Our simulation results suggest that ice particles are mainly formed by water condensation on emitted soot particles. The growth of ice coated soot particles is driven by water vapor emissions in the first 1000 m and by ambient relative humidity afterwards. The presence of chemi-ions does not significantly contribute to the formation of ice particles in the soot-rich regime, and the effect of fuel sulfur contents is small over the range typical of standard jet fuels. The initial properties of soot emissions play the most critical role, and our calculations suggest that higher number concentration and smaller size of contrail particle nuclei may be able to effectively suppress the formation of contrail ice particles. Further modeling and experimental studies are needed to verify if our findings can provide a possible approach for contrail mitigation.

Competition for water vapour results in suppression of ice formation in mixed-phase clouds

Directory of Open Access Journals (Sweden)

E. L. Simpson

2018-05-01

Full Text Available The formation of ice in clouds can initiate precipitation and influence a cloud's reflectivity and lifetime, affecting climate to a highly uncertain degree. Nucleation of ice at elevated temperatures requires an ice nucleating particle (INP, which results in so-called heterogeneous freezing. Previously reported measurements for the ability of a particle to nucleate ice have been made in the absence of other aerosol which will act as cloud condensation nuclei (CCN and are ubiquitous in the atmosphere. Here we show that CCN can outcompete INPs for available water vapour thus suppressing ice formation, which has the potential to significantly affect the Earth's radiation budget. The magnitude of this suppression is shown to be dependent on the mass of condensed water required for freezing. Here we show that ice formation in a state-of-the-art cloud parcel model is strongly dependent on the criteria for heterogeneous freezing selected from those previously hypothesised. We have developed an alternative criteria which agrees well with observations from cloud chamber experiments. This study demonstrates the dominant role that competition for water vapour can play in ice formation, highlighting both a need for clarity in the requirements for heterogeneous freezing and for measurements under atmospherically appropriate conditions.

Competition for water vapour results in suppression of ice formation in mixed-phase clouds

Science.gov (United States)

Simpson, Emma L.; Connolly, Paul J.; McFiggans, Gordon

2018-05-01

The formation of ice in clouds can initiate precipitation and influence a cloud's reflectivity and lifetime, affecting climate to a highly uncertain degree. Nucleation of ice at elevated temperatures requires an ice nucleating particle (INP), which results in so-called heterogeneous freezing. Previously reported measurements for the ability of a particle to nucleate ice have been made in the absence of other aerosol which will act as cloud condensation nuclei (CCN) and are ubiquitous in the atmosphere. Here we show that CCN can outcompete INPs for available water vapour thus suppressing ice formation, which has the potential to significantly affect the Earth's radiation budget. The magnitude of this suppression is shown to be dependent on the mass of condensed water required for freezing. Here we show that ice formation in a state-of-the-art cloud parcel model is strongly dependent on the criteria for heterogeneous freezing selected from those previously hypothesised. We have developed an alternative criteria which agrees well with observations from cloud chamber experiments. This study demonstrates the dominant role that competition for water vapour can play in ice formation, highlighting both a need for clarity in the requirements for heterogeneous freezing and for measurements under atmospherically appropriate conditions.

Percolation blockage: A process that enables melt pond formation on first year Arctic sea ice

Science.gov (United States)

Polashenski, Chris; Golden, Kenneth M.; Perovich, Donald K.; Skyllingstad, Eric; Arnsten, Alexandra; Stwertka, Carolyn; Wright, Nicholas

2017-01-01

Melt pond formation atop Arctic sea ice is a primary control of shortwave energy balance in the Arctic Ocean. During late spring and summer, the ponds determine sea ice albedo and how much solar radiation is transmitted into the upper ocean through the sea ice. The initial formation of ponds requires that melt water be retained above sea level on the ice surface. Both theory and observations, however, show that first year sea ice is so highly porous prior to the formation of melt ponds that multiday retention of water above hydraulic equilibrium should not be possible. Here we present results of percolation experiments that identify and directly demonstrate a mechanism allowing melt pond formation. The infiltration of fresh water into the pore structure of sea ice is responsible for blocking percolation pathways with ice, sealing the ice against water percolation, and allowing water to pool above sea level. We demonstrate that this mechanism is dependent on fresh water availability, known to be predominantly from snowmelt, and ice temperature at melt onset. We argue that the blockage process has the potential to exert significant control over interannual variability in ice albedo. Finally, we suggest that incorporating the mechanism into models would enhance their physical realism. Full treatment would be complex. We provide a simple temperature threshold-based scheme that may be used to incorporate percolation blockage behavior into existing model frameworks.

Ice formation in PEM fuel cells operated isothermally at sub-freezing temperatures

Energy Technology Data Exchange (ETDEWEB)

Mukundan, Rangachary [Los Alamos National Laboratory; Luhan, Roger W [Los Alamos National Laboratory; Davey, John R [Los Alamos National Laboratory; Spendelow, Jacob S [Los Alamos National Laboratory; Borup, Rodney L [Los Alamos National Laboratory; Hussey, Daniel S [NIST; Jacobson, David L [NIST; Arif, Muhammad [NIST

2009-01-01

The effect of MEA and GDL structure and composition on the performance of single-PEM fuel cells operated isothermally at subfreezing temperatures is presented. The cell performance and durability are not only dependent on the MEA/GDL materials used but also on their interfaces. When a cell is operated isothermally at sub-freezing temperatures in constant current mode, the water formation due to the current density initially hydrates the membrane/ionomer and then forms ice in the catalyst layer/GDL. An increase in high frequency resistance was also observed in certain MEAs where there is a possibility of ice formation between the catalyst layer and GDL leading to a loss in contact area. The total water/ice holding capacity for any MEA was lower at lower temperatures and higher current densities. The durability of MEAs subjected to multiple isothermal starts was better for LANL prepared MEAs as compared to commercial MEAs, and cloth GDLs when compared to paper GDLs. The ice formation was monitored using high-resolution neutron radiography and was found to be concentrated near the cathode catalyst layer. However, there was significant ice formation in the GDLs especially at the higher temperature ({approx} -10 C) and lower current density (0.02 A/cm{sup 2}) operations. These results are consistent with the longer-term durability observations that show more severe degradation at the lower temperatures.

78 FR 44090 - Formaldehyde; Third-Party Certification Framework for the Formaldehyde Standards for Composite...

Science.gov (United States)

2013-07-23

... Formaldehyde; Third-Party Certification Framework for the Formaldehyde Standards for Composite Wood Products..., concerning a third-party certification framework for the formaldehyde standards for composite wood products... Environmental protection, Composite wood products, Formaldehyde, Reporting and recordkeeping, Third-party...

Initial inventory of alternatives to biocidal products containing formaldehyde of formaldehyde releasers

NARCIS (Netherlands)

Wezenbeek JM; Janssen MPM; Scheepmaker JWA; MSP; M&V

2015-01-01

Formaldehyde is de werkzame stof in veel desinfecteer- en conserveringsmiddelen, maar deze stof is kankerverwekkend. Daarom zal formaldehyde naar verwachting per 1 januari 2016 op Europees niveau als zodanig worden geclassificeerd (carcinogeen 1B). Dit kan betekenen dat formaldehyde-houdende

On the Formation of Interstellar Water Ice: Constraints from a Search for Hydrogen Peroxide Ice in Molecular Clouds

Science.gov (United States)

Smith, R. G.; Charnely, S. B.; Pendleton, Y. J.; Wright, C. M.; Maldoni, M. M.; Robinson, G.

2011-01-01

Recent surface chemistry experiments have shown that the hydrogenation of molecular oxygen on interstellar dust grains is a plausible formation mechanism, via hydrogen peroxide (H2O2), for the production of water (H2O) ice mantles in the dense interstellar medium. Theoretical chemistry models also predict the formation of a significant abundance of H2O2 ice in grain mantles by this route. At their upper limits, the predicted and experimental abundances are sufficiently high that H2O2 should be detectable in molecular cloud ice spectra. To investigate this further, laboratory spectra have been obtained for H2O2/H2O ice films between 2.5 and 200 micron, from 10 to 180 K, containing 3%, 30%, and 97% H2O2 ice. Integrated absorbances for all the absorption features in low-temperature H2O2 ice have been derived from these spectra. For identifying H2O2 ice, the key results are the presence of unique features near 3.5, 7.0, and 11.3 micron. Comparing the laboratory spectra with the spectra of a group of 24 protostars and field stars, all of which have strong H2O ice absorption bands, no absorption features are found that can definitely be identified with H2O2 ice. In the absence of definite H2O2 features, the H2O2 abundance is constrained by its possible contribution to the weak absorption feature near 3.47 micron found on the long-wavelength wing of the 3 micron H2O ice band. This gives an average upper limit for H2O2, as a percentage of H2O, of 9% +/- 4%. This is a strong constraint on parameters for surface chemistry experiments and dense cloud chemistry models.

An improved model for nucleation-limited ice formation in living cells during freezing.

Directory of Open Access Journals (Sweden)

Jingru Yi

Full Text Available Ice formation in living cells is a lethal event during freezing and its characterization is important to the development of optimal protocols for not only cryopreservation but also cryotherapy applications. Although the model for probability of ice formation (PIF in cells developed by Toner et al. has been widely used to predict nucleation-limited intracellular ice formation (IIF, our data of freezing Hela cells suggest that this model could give misleading prediction of PIF when the maximum PIF in cells during freezing is less than 1 (PIF ranges from 0 to 1. We introduce a new model to overcome this problem by incorporating a critical cell volume to modify the Toner's original model. We further reveal that this critical cell volume is dependent on the mechanisms of ice nucleation in cells during freezing, i.e., surface-catalyzed nucleation (SCN and volume-catalyzed nucleation (VCN. Taken together, the improved PIF model may be valuable for better understanding of the mechanisms of ice nucleation in cells during freezing and more accurate prediction of PIF for cryopreservation and cryotherapy applications.

ON THE FORMATION OF CO2 AND OTHER INTERSTELLAR ICES

International Nuclear Information System (INIS)

Garrod, R. T.; Pauly, T.

2011-01-01

We investigate the formation and evolution of interstellar dust-grain ices under dark-cloud conditions, with a particular emphasis on CO 2 . We use a three-phase model (gas/surface/mantle) to simulate the coupled gas-grain chemistry, allowing the distinction of the chemically active surface from the ice layers preserved in the mantle beneath. The model includes a treatment of the competition between barrier-mediated surface reactions and thermal-hopping processes. The results show excellent agreement with the observed behavior of CO 2 , CO, and water ice in the interstellar medium. The reaction of the OH radical with CO is found to be efficient enough to account for CO 2 ice production in dark clouds. At low visual extinctions, with dust temperatures ∼>12 K, CO 2 is formed by direct diffusion and reaction of CO with OH; we associate the resultant CO 2 -rich ice with the observational polar CO 2 signature. CH 4 ice is well correlated with this component. At higher extinctions, with lower dust temperatures, CO is relatively immobile and thus abundant; however, the reaction of H and O atop a CO molecule allows OH and CO to meet rapidly enough to produce a CO:CO 2 ratio in the range ∼2-4, which we associate with apolar signatures. We suggest that the observational apolar CO 2 /CO ice signatures in dark clouds result from a strongly segregated CO:H 2 O ice, in which CO 2 resides almost exclusively within the CO component. Observed visual-extinction thresholds for CO 2 , CO, and H 2 O are well reproduced by depth-dependent models. Methanol formation is found to be strongly sensitive to dynamical timescales and dust temperatures.

A Theoretical Investigation of the Plausibility of Reactions Between Ammonia and Carbonyl Species (Formaldehyde, Acetaldehyde, and Acetone) in Interstellar Ice Analogs at Ultracold Temperatures

Science.gov (United States)

Chen, Lina; Woon, David E.

2011-01-01

We have reexamined the reaction between formaldehyde and ammonia, which was previously studied by us and other workers in modestly sized cluster calculations. Larger model systems with up to 12H2O were employed, and reactions of two more carbonyl species, acetaldehyde and acetone, were also carried out. Calculations were performed at the B3LYP/6-31+G** level with bulk solvent effects treated with a polarizable continuum model; limited MP2/6-31+G** calculations were also performed. We found that while the barrier for the concerted proton relay mechanism described in previous work remains modest, it is still prohibitively high for the reaction to occur under the ultracold conditions that prevail in dense interstellar clouds. However, a new pathway emerged in more realistic clusters that involves at least one barrierless step for two of the carbonyl species considered here: ammonia reacts with formaldehyde and acetaldehyde to form a partial charge transfer species in small clusters (4H2O) and a protonated hydroxyamino intermediate species in large clusters (9H2O, 12H2O); modest barriers that decrease sharply with cluster size are found for the analogous processes for the acetone-NH3 reaction. Furthermore, if a second ammonia replaces one of the water molecules in calculations in the 9H2O clusters, deprotonation can occur to yield the same neutral hydroxyamino species that is formed via the original concerted proton relay mechanism. In at least one position, deprotonation is barrierless when zero-point energy is included. In addition to describing the structures and energetics of the reactions between formaldehyde, acetaldehyde, and acetone with ammonia, we report spectroscopic predictions of the observable vibrational features that are expected to be present in ice mixtures of different composition.

Organic Compounds Produced by Photolysis of Realistic Interstellar and Cometary Ice Analogs Containing Methanol

Science.gov (United States)

Bernstein, Max P.; Sandford, Scott A.; Allamandola, Louis J.; Chang, Sherwood; Scharberg, Maureen A.

1995-01-01

The InfraRed (IR) spectra of UltraViolet (UV) and thermally processed, methanol-containing interstellar / cometary ice analogs at temperatures from 12 to 300 K are presented. Infrared spectroscopy, H-1 and C-13 Nuclear Magnetic Resonance (NMR) spectroscopy, and gas chromatography-mass spectrometry indicate that CO (carbon monoxide), CO2 (carbon dioxide), CH4 (methane), HCO (the formyl radical), H2CO (formaldehyde), CH3CH2OH (ethanol), HC([double bond]O)NH2 (formamide), CH3C([double bond]O)NH2 (acetamide), and R[single bond]C[triple bond]N (nitriles) are formed. In addition, the organic materials remaining after photolyzed ice analogs have been warmed to room temperature contain (in rough order of decreasing abundance), (1) hexamethylenetetramine (HMT, C6H12N4), (2) ethers, alcohols, and compounds related to PolyOxyMethylene (POM, ([single bond]CH2O[single bond](sub n)), and (3) ketones (R[single bond]C([double bond]O)[single bond]R') and amides (H2NC([double bond]O)[single bond]R). Most of the carbon in these residues is thought to come from the methanol in the original ice. Deuterium and C-13 isotopic labeling demonstrates that methanol is definitely the source of carbon in HMT. High concentrations of HMT in interstellar and cometary ices could have important astrophysical consequences. The ultraviolet photolysis of HMT frozen in H2O ice readily produces the 'XCN' band observed in the spectra of protostellar objects and laboratory ices, as well as other nitriles. Thus, HMT may be a precursor of XCN and a source of CN in comets and the interstellar medium. Also, HMT is known to hydrolyze under acidic conditions to yield ammonia, formaldehyde, and amino acids. Thus, HMT may be a significant source of prebiogenic compounds on asteroidal parent bodies. A potential mechanism for the radiative formation of HMT in cosmic ices is outlined.

Ice-lens formation and geometrical supercooling in soils and other colloidal materials

KAUST Repository

Style, Robert W.; Peppin, Stephen S. L.; Cocks, Alan C. F.; Wettlaufer, J. S.

2011-01-01

We present a physically intuitive model of ice-lens formation and growth during the freezing of soils and other dense, particulate suspensions. Motivated by experimental evidence, we consider the growth of an ice-filled crack in a freezing soil

Estimation of formaldehyde concentration in working environment by using 14C-labeled formaldehyde

International Nuclear Information System (INIS)

Hamada, Masana; Kitano, Katsuhiro; Miketa, Daigo

2010-01-01

It became to be ruled to check the concentration of formaldehyde as the estimation of airborne concentration in working environment since March, 2009 and then, liquid chromatography and easily analyzing equipment methods, mainly gas detector tube method, are given as the official methods. When we estimate the airborne formaldehyde concentration in a work place where only formalin is used as a formaldehyde emission source such as a room for pathological examination, it is not necessary to separate formaldehyde and therefore not very reasonable to use liquid chromatography including troublesome procedures. On the other hand, gas detector tube method is convenient but has possibility of causing errors by individual differences. The errors might cause the additional differences of the control classes and of the measures to prevent workers from being exposed to harmful materials. In order to solve these problems and to exam alternative analyzing method for formaldehyde, we tried to measure the concentration by using 14 C-labelled one. After 14 C-labelled formaldehyde solution is put into the emission source of formaldehyde (formalin solution), the vaporized samples are taken by silica gel tubes quantitatively as usual at the estimation of airborne concentration in working environment. By counting the desorpted amount of radioactivity from silica gel, it was revealed that the obtained concentrations of formaldehyde are correspond to both the calculated values and the values indicated on the gas detector tubes at various concentrations. In this study, we used the amount below the lower activity limits of radioactive material. Except the users who have radioisotope controlled area, we are allowed to use 14 C-labeled materials below 10 MBq without being regulated under the Law Concerning Prevention of Radiation Hazards. When we use a little amount of 14 C-formaldehyde at formaldehyde using area to check the concentration of vaporized formaldehyde, this method was found to

Control and prevention of ice formation and accretion on heat exchangers for ventilation systems

DEFF Research Database (Denmark)

Rahimi, Maral; Afshari, Alireza

2015-01-01

In cold climates, the application of mechanical ventilation systems with heat recovery like are airto-air exchangers is used for reducing energy consumption for heating buildings by transferring heat exhausted air to supply air. However, increase efficiency of heat exchanger results in lower...... exhaust air temperatures and Ice formation on heat exchanger fins, which can cause problem and is not favourable. Therefore, prevention and control of ice formation on heat exchangers is necessary. The existing methods are divided into two different methods: active and passive ice control methods....... The active methods are e.g. bypass, recirculation, preheating. The passive methods relate to the surface characteristics of the heat exchanger fins as they have effect on ice formation in initial phase. All these methods have varying levels of success, cost, and effectiveness, which are depending on the heat...

Solid-state /sup 13/C NMR study of cured resorcinol-formaldehyde resins

Energy Technology Data Exchange (ETDEWEB)

Lippmaa, H.; Samoson, A.

1988-08-01

The curing process generally follows the pattern observed in the stage of prepolymer formation. Catalysts (NaOH, hexa, Mg(OCOCH/sub 3/)/sub 2/) that have no substantial influence on the isomeric composition of the resorcinol-formaldehyde prepolymers, do not affect the isomeric composition of the cured resins to any significant extent either. Isomeric composition of the cured resins depends mostly on the presence of water during the curing process, necessary for depolymerisation of the added paraformaldehyde. Curing in the melt leads to enhanced 2-substitution in the 1,3-dihydroxybenzene rings. In the /sup 13/C NMR spectra of cured powdered samples, the tendency of 5-methylresorcinol to form oligomers with a higher degree of 2-substitution than resorcinol is clearly apparent. Polycondensation process continues in the powdered resins after initial curing until complete consumption of all formaldehyde. Curing of phenol-formaldehyde resols proceeds through intermediate dimethylene ether formation.

ON THE FORMATION OF INTERSTELLAR WATER ICE: CONSTRAINTS FROM A SEARCH FOR HYDROGEN PEROXIDE ICE IN MOLECULAR CLOUDS

Energy Technology Data Exchange (ETDEWEB)

Smith, R. G.; Wright, C. M.; Robinson, G. [School of Physical, Environmental and Mathematical Sciences, University of New South Wales, Australian Defence Force Academy, Canberra, ACT 2600 (Australia); Charnley, S. B. [Astrochemistry Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Pendleton, Y. J. [NASA Lunar Science Institute, NASA Ames Research Center, Moffett Field, CA 94035 (United States); Maldoni, M. M., E-mail: r.smith@adfa.edu.au, E-mail: c.wright@adfa.edu.au, E-mail: g.robinson@adfa.edu.au, E-mail: Steven.B.Charnley@nasa.gov, E-mail: yvonne.pendleton@nasa.gov [Geoscience Australia, Canberra, ACT 2601 (Australia)

2011-12-20

Recent surface chemistry experiments have shown that the hydrogenation of molecular oxygen on interstellar dust grains is a plausible formation mechanism, via hydrogen peroxide (H{sub 2}O{sub 2}), for the production of water (H{sub 2}O) ice mantles in the dense interstellar medium. Theoretical chemistry models also predict the formation of a significant abundance of H{sub 2}O{sub 2} ice in grain mantles by this route. At their upper limits, the predicted and experimental abundances are sufficiently high that H{sub 2}O{sub 2} should be detectable in molecular cloud ice spectra. To investigate this further, laboratory spectra have been obtained for H{sub 2}O{sub 2}/H{sub 2}O ice films between 2.5 and 200 {mu}m, from 10 to 180 K, containing 3%, 30%, and 97% H{sub 2}O{sub 2} ice. Integrated absorbances for all the absorption features in low-temperature H{sub 2}O{sub 2} ice have been derived from these spectra. For identifying H{sub 2}O{sub 2} ice, the key results are the presence of unique features near 3.5, 7.0, and 11.3 {mu}m. Comparing the laboratory spectra with the spectra of a group of 24 protostars and field stars, all of which have strong H{sub 2}O ice absorption bands, no absorption features are found that can definitely be identified with H{sub 2}O{sub 2} ice. In the absence of definite H{sub 2}O{sub 2} features, the H{sub 2}O{sub 2} abundance is constrained by its possible contribution to the weak absorption feature near 3.47 {mu}m found on the long-wavelength wing of the 3 {mu}m H{sub 2}O ice band. This gives an average upper limit for H{sub 2}O{sub 2}, as a percentage of H{sub 2}O, of 9% {+-} 4%. This is a strong constraint on parameters for surface chemistry experiments and dense cloud chemistry models.

78 FR 34795 - Formaldehyde; Third-Party Certification Framework for the Formaldehyde Standards for Composite...

Science.gov (United States)

2013-06-10

... Formaldehyde; Third-Party Certification Framework for the Formaldehyde Standards for Composite Wood Products... Certification Framework for the Formaldehyde Standards for Composite Wood Products AGENCY: Environmental... certification, auditing and reporting of third-party certifiers, recordkeeping, enforcement, laminated products...

The study of ikaite formation in sea ice

Science.gov (United States)

Hu, Y.; Nehrke, G.; Dieckmann, G.; Völker, C.; Wolf-Gladrow, D.

2012-04-01

Ikaite (CaCO3.6H2O) is a metastable mineral of calcium carbonate, which is usually found in environments characterized by low temperature (below 5° C), high pH, high alkalinity, high concentration of phosphate and organic matter. Although synthetic CaCO3.6H2O was already known from laboratory studies in 1865, ikaite was first observed in nature in 1963. Recently, Dieckmann et al. (2008, 2010) discovered this mineral in sea ice, which at the same time, was the first direct proof of CaCO3 precipitation in sea ice. However, little is known about the mechanism of ikaite formation in sea ice. Our study focuses on how physico-chemical processes in sea ice affect the formation of ikaite. Experiments were set up at pH ranging from 8.5 to 9.0, and salinity ranging from 0 to 105 at 0 ° C, in order to examine the effect of pH, salinity and also phosphate on the formation of ikaite. Preliminary results read: (1) Experiments show that ikaite can form at different pH levels (8.5~9.0). At high pH, the induction time (the time when the crystals start to precipitate) is shorter which means high pH favours the formation of ikaite. This might be expected given higher CO32- concentrations and thus higher saturation levels for ikaite with increasing pH. (2) The results of experiments with different salinities show that ikaite can form over wide range of salinities from 0 to 105 both in Artificial Sea Water (ASW) and NaCl solution in the presence of phosphate. In ASW, the induction time increases with salinity from S = 0 to S =105; while in NaCl solution, the induction time first increases with salinity and then decreases with the further increase of salinity. Salinity plays both positive and negative roles in the formation of ikaite. On the one hand, the increase in salinity will increase the fraction of CO32- in DIC. On the other hand, the increase in salinity means more ions are involved in the solution, which will reduce the activities of Ca2+ and CO32-by forming ion pairs with

Formation of Ice Giant Satellites During Thommes Model Mirgration

Science.gov (United States)

Fuse, Christopher; Spiegelberg, Josephine

2018-01-01

Inconsistencies between ice giant planet characteristics and classic planet formation theories have led to a re-evaluation of the formation of the outer Solar system. Thommes model migration delivers proto-Uranus and Neptune from orbits interior to Saturn to their current locations. The Thommes model has also been able to reproduce the large Galilean and Saturnian moons via interactions between the proto-ice giants and the gas giant moon disks.As part of a series of investigations examining the effects of Thommes model migration on the formation of moons, N-body simulations of the formation of the Uranian and Neptunian satellite systems were performed. Previous research has yielded conflicting results as to whether satellite systems are stable during planetary migration. Some studies, such as Beaugé (2002) concluded that the system was not stable over the proposed duration of migration. Conversely, Fuse and Neville (2011) and Yokoyama et al. (2011) found that moons were retained, though the nature of the resulting system was heavily influenced by interactions with planetesimals and other large objects. The results of the current study indicate that in situ simulations of the Uranus and Neptune systems can produce stable moons. Whether with current orbital parameters or located at pre-migration, inner Solar system semi-major axes, the simulations end with 5.8 ± 0.15 or 5.9 ± 0.7 regular satellites around Uranus and Neptune, respectively. Preliminary simulations of a proto-moon disk around a single planet migrating via the Thommes model have failed to retain moons. Furthermore, simulations of ejection of the current Uranian satellite system retained at most one moon. Thus, for the Thommes model to be valid, it is likely that moon formation did not begin until after migration ended. Future work will examine the formation of gas and ice giant moons through other migration theories, such as the Nice model (Tsiganis et al. 2006).

MATHEMATICAL MODEL OF ICE FORMATION ON TEPLOOBMENNOGO SIDE OF THETHERMOELECTRIC DESALINATION PLANT

Directory of Open Access Journals (Sweden)

A. M. Gajiyev

2016-01-01

Full Text Available Abstract. The necessity of the use of technology and analytically summarizes the methods of desalination of seawater and brackish waters. Tasked to investigate the processes occurring in the desalination plant with the continuous process of freezing of ice on heat transfer surface with a film mode of fluid motion.To solve this problem the article deals with mathematical cal model of ice formation on heat transfer surfaces and thermo-electric distiller. The model allows us to estimate the rise time and the thickness of the ice under specified conditions of temperature and flow of water. It is shown that the use of thermoelectric converters allows the flexibility to adjust the mode of ice formation. Solved the problem of determining the maximum thickness of the ice at which freezing is possible film of water flowing through it at a predetermined temperature of the cooling plate and the cooling capacity of the thermoelectric battery.It is established that the performance of thermoelectric opreznitive of the system increases due to the increase in the number of cooled surfaces, and the use of the heat from the hot junction of the converters for melting of ice increases the energy efficiency of the system as a whole. 

Growth of Candida boidinii on methanol and the activity of methanol-degrading enzymes as affected from formaldehyde and methylformate.

Science.gov (United States)

Aggelis, G; Margariti, N; Kralli, C; Flouri, F

2000-06-23

Formaldehyde and methylformate affect the growth of Candida boidinii on methanol and the activity of methanol-degrading enzymes. The presence of both intermediates in the feeding medium caused an increase in biomass yield and productivity and a decrease in the specific rate of methanol consumption. In the presence of formaldehyde, the activity of formaldehyde dehydrogenase and formate dehydrogenase was essentially increased, whereas the activity of methanol oxidase was decreased. On the contrary, the presence of methylformate caused an increase of the activity of methanol oxidase and a decrease of the activity of formaldehyde dehydrogenase and formate dehydrogenase. Interpretations concerning the yeast behavior in the presence of intermediate oxidation products were considered and discussed.

78 FR 51696 - Formaldehyde; Third-Party Certification Framework for the Formaldehyde Standards for Composite...

Science.gov (United States)

2013-08-21

... Formaldehyde; Third-Party Certification Framework for the Formaldehyde Standards for Composite Wood Products..., concerning a third-party certification framework for the formaldehyde standards for composite wood products... INFORMATION CONTACT. List of Subjects in 40 CFR Part 770 Environmental protection, Composite wood products...

The effect of surface modification on initial ice formation on aluminum surfaces

DEFF Research Database (Denmark)

Rahimi, Maral; Afshari, Alireza; Fojan, Peter

2015-01-01

material of heat exchanger fins is aluminum, this paper focuses on the effect of aluminum wettability on the initial stages of ice formation. The ice growth was studied on bare as well as hydrophilically and hydrophobically modified surfaces of aluminum (8011A) sheets, commonly used in heat exchangers...

Melamine-formaldehyde aerogels

Science.gov (United States)

Pekala, Richard Walter

1992-01-01

Organic aerogels that are transparent and essentially colorless are prepa from the aqueous, sol-gel polymerization of melamine with formaldehyde. The melamine-formaldehyde (MF) aerogels have low densities, high surface areas, continuous porsity, ultrafine cell/pore sizes, and optical clarity.

Southern Ocean frontal structure and sea-ice formation rates revealed by elephant seals

Science.gov (United States)

Charrassin, J.-B.; Hindell, M.; Rintoul, S. R.; Roquet, F.; Sokolov, S.; Biuw, M.; Costa, D.; Boehme, L.; Lovell, P.; Coleman, R.; Timmermann, R.; Meijers, A.; Meredith, M.; Park, Y.-H.; Bailleul, F.; Goebel, M.; Tremblay, Y.; Bost, C.-A.; McMahon, C. R.; Field, I. C.; Fedak, M. A.; Guinet, C.

2008-01-01

Polar regions are particularly sensitive to climate change, with the potential for significant feedbacks between ocean circulation, sea ice, and the ocean carbon cycle. However, the difficulty in obtaining in situ data means that our ability to detect and interpret change is very limited, especially in the Southern Ocean, where the ocean beneath the sea ice remains almost entirely unobserved and the rate of sea-ice formation is poorly known. Here, we show that southern elephant seals (Mirounga leonina) equipped with oceanographic sensors can measure ocean structure and water mass changes in regions and seasons rarely observed with traditional oceanographic platforms. In particular, seals provided a 30-fold increase in hydrographic profiles from the sea-ice zone, allowing the major fronts to be mapped south of 60°S and sea-ice formation rates to be inferred from changes in upper ocean salinity. Sea-ice production rates peaked in early winter (April–May) during the rapid northward expansion of the pack ice and declined by a factor of 2 to 3 between May and August, in agreement with a three-dimensional coupled ocean–sea-ice model. By measuring the high-latitude ocean during winter, elephant seals fill a “blind spot” in our sampling coverage, enabling the establishment of a truly global ocean-observing system. PMID:18695241

Numerical simulation of formation and preservation of Ningwu ice cave, Shanxi, China

Science.gov (United States)

Yang, S.; Shi, Y.

2015-10-01

Ice caves exist in locations where annual average air temperature is higher than 0 °C. An example is Ningwu ice cave, Shanxi Province, the largest ice cave in China. In order to quantitatively investigate the mechanism of formation and preservation of the ice cave, we use the finite-element method to simulate the heat transfer process at this ice cave. There are two major control factors. First, there is the seasonal asymmetric heat transfer. Heat is transferred into the ice cave from outside very inefficiently by conduction in spring, summer and fall. In winter, thermal convection occurs that transfers heat very efficiently out of the ice cave, thus cooling it down. Secondly, ice-water phase change provides a heat barrier for heat transfer into the cave in summer. The calculation also helps to evaluate effects of global warming, tourists, colored lights, climatic conditions, etc. for sustainable development of the ice cave as a tourism resource. In some other ice caves in China, managers have installed airtight doors at these ice caves' entrances with the intention of "protecting" these caves, but this in fact prevents cooling in winter and these cave ices will entirely melt within tens of years.

Satellite remote sensing of dust aerosol indirect effects on ice cloud formation.

Science.gov (United States)

Ou, Steve Szu-Cheng; Liou, Kuo-Nan; Wang, Xingjuan; Hansell, Richard; Lefevre, Randy; Cocks, Stephen

2009-01-20

We undertook a new approach to investigate the aerosol indirect effect of the first kind on ice cloud formation by using available data products from the Moderate-Resolution Imaging Spectrometer (MODIS) and obtained physical understanding about the interaction between aerosols and ice clouds. Our analysis focused on the examination of the variability in the correlation between ice cloud parameters (optical depth, effective particle size, cloud water path, and cloud particle number concentration) and aerosol optical depth and number concentration that were inferred from available satellite cloud and aerosol data products. Correlation results for a number of selected scenes containing dust and ice clouds are presented, and dust aerosol indirect effects on ice clouds are directly demonstrated from satellite observations.

Parameterizing the competition between homogeneous and heterogeneous freezing in ice cloud formation – polydisperse ice nuclei

Directory of Open Access Journals (Sweden)

D. Barahona

2009-08-01

Full Text Available This study presents a comprehensive ice cloud formation parameterization that computes the ice crystal number, size distribution, and maximum supersaturation from precursor aerosol and ice nuclei. The parameterization provides an analytical solution of the cloud parcel model equations and accounts for the competition effects between homogeneous and heterogeneous freezing, and, between heterogeneous freezing in different modes. The diversity of heterogeneous nuclei is described through a nucleation spectrum function which is allowed to follow any form (i.e., derived from classical nucleation theory or from observations. The parameterization reproduces the predictions of a detailed numerical parcel model over a wide range of conditions, and several expressions for the nucleation spectrum. The average error in ice crystal number concentration was −2.0±8.5% for conditions of pure heterogeneous freezing, and, 4.7±21% when both homogeneous and heterogeneous freezing were active. The formulation presented is fast and free from requirements of numerical integration.

Formaldehyde in reusable protective gloves.

Science.gov (United States)

Pontén, Ann

2006-05-01

Due to the clinical findings in a single patient's case, formaldehyde was suspected to be present in clinically relevant levels in reusable protective gloves. Therefore, 9 types of gloves were investigated with the semi-quantitative chromotropic acid method. It was found that 6/9 gloves emitted some formaldehyde and that 4/9 gloves emitted > or =40 microg of formaldehyde. Most of the formaldehyde was found on the inside of the gloves. To get an indication of the clinical relevance, a comparison with a protective cream declared to contain the formaldehyde-releasing agent diazolidinyl urea was performed by comparing areas of gloves with areas of cream layers with thickness 1-2 mg/cm(2). It was found that the amounts of formaldehyde emitted from the gloves might be in the same range as emitted from a layer of cream.

Ayty: a New Line-List for Hot Formaldehyde

Science.gov (United States)

Al-Refaie, Ahmed Faris; Yurchenko, Sergei N.; Tennyson, Jonathan; Yachmenev, Andrey

2015-06-01

The ExoMol [1] project aims at providing spectroscopic data for key molecules that can be used to characterize the atmospheres of exoplanets and cool stars. Formaldehyde (H2CO) is of growing importance in studying and modelling terrestrial atmospheric chemistry and dynamics. It also has relevance in astrophysical phenomena that include interstellar medium abundance, proto-planetary and cometary ice chemistry and masers from extra-galactic sources. However there gaps in currently available absolute intensities and a lack of higher rotational excitations that makes it unfeasible to accurately model high temperature systems such as hot Jupiters. Here we present AYTY [2], a new line list for formaldehyde applicable to temperatures up to 1500 K. AYTY contains almost 10 million states reaching rotational excitations up to J=70 and over 10 billion transitions at up to 10 000 cm-1. The line list was computed using the variational ro-vibrational solver TROVE with a refined ab-initio potential energy surface and dipole moment surface. J.~Tennyson and S.~N. Yurchenko MNRAS, 425:21--33, 2012. A.~F. Al-Refaie, S.~N. Yurchenko, A.~Yachmenev, and J.~Tennyson MNRAS, 2015.

Laboratory and Cloud Chamber Studies of Formation Processes and Properties of Atmospheric Ice Particles

Science.gov (United States)

Leisner, T.; Abdelmonem, A.; Benz, S.; Brinkmann, M.; Möhler, O.; Rzesanke, D.; Saathoff, H.; Schnaiter, M.; Wagner, R.

2009-04-01

The formation of ice in tropospheric clouds controls the evolution of precipitation and thereby influences climate and weather via a complex network of dynamical and microphysical processes. At higher altitudes, ice particles in cirrus clouds or contrails modify the radiative energy budget by direct interaction with the shortwave and longwave radiation. In order to improve the parameterisation of the complex microphysical and dynamical processes leading to and controlling the evolution of tropospheric ice, laboratory experiments are performed at the IMK Karlsruhe both on a single particle level and in the aerosol and cloud chamber AIDA. Single particle experiments in electrodynamic levitation lend themselves to the study of the interaction between cloud droplets and aerosol particles under extremely well characterized and static conditions in order to obtain microphysical parameters as freezing nucleation rates for homogeneous and heterogeneous ice formation. They also allow the observation of the freezing dynamics and of secondary ice formation and multiplication processes under controlled conditions and with very high spatial and temporal resolution. The inherent droplet charge in these experiments can be varied over a wide range in order to assess the influence of the electrical state of the cloud on its microphysics. In the AIDA chamber on the other hand, these processes are observable under the realistic dynamic conditions of an expanding and cooling cloud- parcel with interacting particles and are probed simultaneously by a comprehensive set of analytical instruments. By this means, microphysical processes can be studied in their complex interplay with dynamical processes as for example coagulation or particle evaporation and growth via the Bergeron - Findeisen process. Shortwave scattering and longwave absorption properties of the nucleating and growing ice crystals are probed by in situ polarised laser light scattering measurements and infrared extinction

Supraglacial Lakes in the Percolation Zone of the Western Greenland Ice Sheet: Formation and Development using Operation IceBridge Snow Radar and ATM (2009-2014)

Science.gov (United States)

Chen, C.; Howat, I. M.; de la Peña, S.

2015-12-01

Surface meltwater lakes on the Greenland Ice Sheet have appeared at higher elevations, extending well into the percolation zone, under recent warming, with the largest expansion occurring in the western Greenland Ice Sheet. The conditions that allow lakes to form atop firn are poorly constrained, but the formation of new lakes imply changes in the permeability of the firn at high elevations, promoting meltwater runoff. We explore the formation and evolution of new surface lakes in this region above 1500 meters, using a combination of satellite imagery and repeat Snow (2-6.5 GHz) radar echograms and LIDAR measurements from NASA's Operation IceBridge of 2009-2014. We identify conditions for surface lake formation at their farthest inland extent and suggest behaviors of persistence and lake drainage are due to differences in regional ice dynamics.

EXPLORING THE POTENTIAL FORMATION OF ORGANIC SOLIDS IN CHONDRITES AND COMETS THROUGH POLYMERIZATION OF INTERSTELLAR FORMALDEHYDE

International Nuclear Information System (INIS)

Kebukawa, Yoko; Cody, George D.; David Kilcoyne, A. L.

2013-01-01

Polymerization of interstellar formaldehyde, first through the formose reaction and then through subsequent condensation reactions, provides a plausible explanation for how abundant and highly chemically complex organic solids may have come to exist in primitive solar system objects. In order to gain better insight on the reaction, a systematic study of the relationship of synthesis temperature with resultant molecular structure was performed. In addition, the effect of the presence of ammonia on the reaction rate and molecular structure of the product was studied. The synthesized formaldehyde polymer is directly compared to chondritic insoluble organic matter (IOM) isolated from primitive meteorites using solid-state 13 C nuclear magnetic resonance, Fourier transform infrared, and X-ray absorption near edge structure spectroscopy. The molecular structure of the formaldehyde polymer is shown to exhibit considerable similarity at the functional group level with primitive chondritic IOM. The addition of ammonia to the solution enhances the rate of polymerization reaction at lower temperatures and results in substantial incorporation of nitrogen into the polymer. Morphologically, the formaldehyde polymer exists as submicron to micron-sized spheroidal particles and spheroidal particle aggregates that bare considerable similarity to the organic nanoglobules commonly observed in chondritic IOM. These spectroscopic and morphological data support the hypothesis that IOM in chondrites and refractory organic carbon in comets may have formed through the polymerization of interstellar formaldehyde after planetesimal accretion, in the presence of liquid water, early in the history of the solar system.

EXPLORING THE POTENTIAL FORMATION OF ORGANIC SOLIDS IN CHONDRITES AND COMETS THROUGH POLYMERIZATION OF INTERSTELLAR FORMALDEHYDE

Energy Technology Data Exchange (ETDEWEB)

Kebukawa, Yoko; Cody, George D. [Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road NW, Washington, DC 20015 (United States); David Kilcoyne, A. L., E-mail: ykebukawa@ciw.edu, E-mail: yoko@ep.sci.hokudai.ac.jp [Advanced Light Source, Lawrence Berkeley National Laboratory, Mail Stop 7R0222, 1 Cyclotron Road, Berkeley, CA 94720 (United States)

2013-07-01

Polymerization of interstellar formaldehyde, first through the formose reaction and then through subsequent condensation reactions, provides a plausible explanation for how abundant and highly chemically complex organic solids may have come to exist in primitive solar system objects. In order to gain better insight on the reaction, a systematic study of the relationship of synthesis temperature with resultant molecular structure was performed. In addition, the effect of the presence of ammonia on the reaction rate and molecular structure of the product was studied. The synthesized formaldehyde polymer is directly compared to chondritic insoluble organic matter (IOM) isolated from primitive meteorites using solid-state {sup 13}C nuclear magnetic resonance, Fourier transform infrared, and X-ray absorption near edge structure spectroscopy. The molecular structure of the formaldehyde polymer is shown to exhibit considerable similarity at the functional group level with primitive chondritic IOM. The addition of ammonia to the solution enhances the rate of polymerization reaction at lower temperatures and results in substantial incorporation of nitrogen into the polymer. Morphologically, the formaldehyde polymer exists as submicron to micron-sized spheroidal particles and spheroidal particle aggregates that bare considerable similarity to the organic nanoglobules commonly observed in chondritic IOM. These spectroscopic and morphological data support the hypothesis that IOM in chondrites and refractory organic carbon in comets may have formed through the polymerization of interstellar formaldehyde after planetesimal accretion, in the presence of liquid water, early in the history of the solar system.

Exploring the Potential Formation of Organic Solids in Chondrites and Comets through Polymerization of Interstellar Formaldehyde

Science.gov (United States)

Kebukawa, Yoko; Kilcoyne, A. L. David; Cody, George D.

2013-07-01

Polymerization of interstellar formaldehyde, first through the formose reaction and then through subsequent condensation reactions, provides a plausible explanation for how abundant and highly chemically complex organic solids may have come to exist in primitive solar system objects. In order to gain better insight on the reaction, a systematic study of the relationship of synthesis temperature with resultant molecular structure was performed. In addition, the effect of the presence of ammonia on the reaction rate and molecular structure of the product was studied. The synthesized formaldehyde polymer is directly compared to chondritic insoluble organic matter (IOM) isolated from primitive meteorites using solid-state 13C nuclear magnetic resonance, Fourier transform infrared, and X-ray absorption near edge structure spectroscopy. The molecular structure of the formaldehyde polymer is shown to exhibit considerable similarity at the functional group level with primitive chondritic IOM. The addition of ammonia to the solution enhances the rate of polymerization reaction at lower temperatures and results in substantial incorporation of nitrogen into the polymer. Morphologically, the formaldehyde polymer exists as submicron to micron-sized spheroidal particles and spheroidal particle aggregates that bare considerable similarity to the organic nanoglobules commonly observed in chondritic IOM. These spectroscopic and morphological data support the hypothesis that IOM in chondrites and refractory organic carbon in comets may have formed through the polymerization of interstellar formaldehyde after planetesimal accretion, in the presence of liquid water, early in the history of the solar system.

Monte Carlo kinetics simulations of ice-mantle formation on interstellar grains

Science.gov (United States)

Garrod, Robin

2015-08-01

The majority of interstellar dust-grain chemical kinetics models use rate equations, or alternative population-based simulation methods, to trace the time-dependent formation of grain-surface molecules and ice mantles. Such methods are efficient, but are incapable of considering explicitly the morphologies of the dust grains, the structure of the ices formed thereon, or the influence of local surface composition on the chemistry.A new Monte Carlo chemical kinetics model, MIMICK, is presented here, whose prototype results were published recently (Garrod 2013, ApJ, 778, 158). The model calculates the strengths and positions of the potential mimima on the surface, on the fly, according to the individual pair-wise (van der Waals) bonds between surface species, allowing the structure of the ice to build up naturally as surface diffusion and chemistry occur. The prototype model considered contributions to a surface particle's potential only from contiguous (or "bonded") neighbors; the full model considers contributions from surface constituents from short to long range. Simulations are conducted on a fully 3-D user-generated dust-grain with amorphous surface characteristics. The chemical network has also been extended from the simple water system previously published, and now includes 33 chemical species and 55 reactions. This allows the major interstellar ice components to be simulated, such as water, methane, ammonia and methanol, as well as a small selection of more complex molecules, including methyl formate (HCOOCH3).The new model results indicate that the porosity of interstellar ices are dependent on multiple variables, including gas density, the dust temperature, and the relative accretion rates of key gas-phase species. The results presented also have implications for the formation of complex organic molecules on dust-grain surfaces at very low temperatures.

FORMALDEHYDE MASERS: EXCLUSIVE TRACERS OF HIGH-MASS STAR FORMATION

Energy Technology Data Exchange (ETDEWEB)

Araya, E. D.; Brown, J. E. [Western Illinois University, Physics Department, 1 University Circle, Macomb, IL 61455 (United States); Olmi, L. [INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy); Ortiz, J. Morales [University of Puerto Rico, Río Piedras Campus, Physical Sciences Department, P.O. Box 23323, San Juan, PR 00931 (United States); Hofner, P.; Creech-Eakman, M. J. [New Mexico Institute of Mining and Technology, Physics Department, 801 Leroy Place, Socorro, NM 87801 (United States); Kurtz, S. [Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Apdo. Postal 3-72, 58089 Morelia, Michoacán (Mexico); Linz, H. [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany)

2015-11-15

The detection of four formaldehyde (H{sub 2}CO) maser regions toward young high-mass stellar objects in the last decade, in addition to the three previously known regions, calls for an investigation of whether H{sub 2}CO masers are an exclusive tracer of young high-mass stellar objects. We report the first survey specifically focused on the search for 6 cm H{sub 2}CO masers toward non high-mass star-forming regions (non HMSFRs). The observations were conducted with the 305 m Arecibo Telescope toward 25 low-mass star-forming regions, 15 planetary nebulae and post-AGB stars, and 31 late-type stars. We detected no H{sub 2}CO emission in our sample of non HMSFRs. To check for the association between high-mass star formation and H{sub 2}CO masers, we also conducted a survey toward 22 high-mass star-forming regions from a Hi-GAL (Herschel infrared Galactic Plane Survey) sample known to harbor 6.7 GHz CH{sub 3}OH masers. We detected a new 6 cm H{sub 2}CO emission line in G32.74−0.07. This work provides further evidence that supports an exclusive association between H{sub 2}CO masers and young regions of high-mass star formation. Furthermore, we detected H{sub 2}CO absorption toward all Hi-GAL sources, and toward 24 low-mass star-forming regions. We also conducted a simultaneous survey for OH (4660, 4750, 4765 MHz), H110α (4874 MHz), HCOOH (4916 MHz), CH{sub 3}OH (5005 MHz), and CH{sub 2}NH (5289 MHz) toward 68 of the sources in our sample of non HMSFRs. With the exception of the detection of a 4765 MHz OH line toward a pre-planetary nebula (IRAS 04395+3601), we detected no other spectral line to an upper limit of 15 mJy for most sources.

Theoretical Analysis on Marangoni-driven Cavity Formation in Ice during In Situ Burning of Oil Spills in Ice-infested Waters

Science.gov (United States)

Farmahini Farahani, H.; Jomaas, G.; Rangwala, A. S.

2017-12-01

In situ burning, intentional burning of discharged oil on the water surface, is a promising response method to oil spill accidents in the Arctic. However, burning of the oil adjacent to ice bodies creates a lateral cavity in the ice. As a result of the cavity formation the removal efficiency which is a key success criterion for in situ burning operation will decrease. The formation of lateral cavities are noticed recently and only a few experimental studies have addressed them. These experiments have shown lateral cavities with a length of severe horizontal temperature gradient which in turn generates a Marangoni flow from hot to cold regions. This is found to be the dominant heat transfer mechanism that is providing the heat for the ice to melt. Here, we introduce an order of magnitude analysis on the governing equations of the ice melting problem to estimate the penetration length of a burning oil near ice. This correlation incorporates the flame heat feedback with the surface flow driven by Marangoni convection. The melting energy continuity is also included in the analysis to complete the energy transfer cycle that leads to melting of the ice. The comparison between this correlation and the existing experimental data shows a very good agreement. Therefore, this correlation can be used to estimate the penetration length for burning of an actual spill and can be applied towards improved guidelines of burning adjacent to ice bodies, so as to enhance the chances for successful implantation of in situ burning.

Adsorption of formaldehyde on graphene and graphyne

Science.gov (United States)

Majidi, R.; Karami, A. R.

2014-05-01

The adsorption of formaldehyde on graphene and graphyne was investigated to search high sensitivity sensors for detection of formaldehyde. We have used density functional theory to study the effect of formaldehyde on the electronic properties of graphene and graphyne. It is found that formaldehyde is physisorbed on the graphene and graphyne with small binding energy, large binding distance, and small charge transfer. The calculations also indicate that formaldehyde adsorption modifies the electronic properties of semimetallic graphene, α-graphyne, and β-graphyne and semiconducting γ-graphyne. The graphene and graphyne show semiconducting property in the presence of formaldehyde. The effect of formaldehyde on the electronic properties of graphene and graphyne suggests the potential application of these carbon nanomaterials for formaldehyde detection.

Formaldehyde Emissions from Urea-Formaldehyde- and no-added-formaldehyde-Bonded particleboard as Influenced by Temperature and Relative Humidity

Science.gov (United States)

Charles R. Frihart; James M. Wescott; Timothy L. Chaffee; Kyle M. Gonner

2012-01-01

It is well documented that temperature and humidity can influence formaldehyde emissions from composite panels that are produced using urea-formaldehyde (UF)–type adhesives. This work investigates the effect of temperature and humidity on newer commercial California Air Resources Board (CARB) phase II–compliant particleboard produced with UF-type adhesives. These...

Sea Ice Formation Rate and Temporal Variation of Temperature and Salinity at the Vicinity of Wilkins Ice Shelf from Data Collected by Southern Elephant Seals in 2008

Science.gov (United States)

Santini, M. F.; Souza, R.; Wainer, I.; Muelbert, M.; Hindell, M.

2013-05-01

The use of marine mammals as autonomous platforms for collecting oceanographic data has revolutionized the understanding of physical properties of low or non-sampled regions of the polar oceans. The use of these animals became possible due to advancements in the development of electronic devices, sensors and batteries carried by them. Oceanographic data collected by two southern elephant seals (Mirounga leonina) during the Fall of 2008 were used to infer the sea-ice formation rate in the region adjacent to the Wilkins Ice Shelf, west of the Antarctic Peninsula at that period. The sea-ice formation rate was estimated from the salt balance equation for the upper (100 m) ocean at a daily frequency for the period between 13 February and 20 June 2008. The oceanographic data collected by the animals were also used to present the temporal variation of the water temperature and salinity from surface to 300 m depth in the study area. Sea ice formation rate ranged between 0,087 m/day in early April and 0,008 m/day in late June. Temperature and salinity ranged from -1.84°C to 1.60°C and 32.85 to 34.85, respectively, for the upper 300 m of the water column in the analyzed period. The sea-ice formation rate estimations do not consider water advection, only temporal changes of the vertical profile of salinity. This may cause underestimates of the real sea-ice formation rate. The intense reduction of sea ice rate formation from April to June 2008 may be related to the intrusion of the Circumpolar Depth Water (CDW) into the study region. As a consequence of that we believe that this process can be partly responsible for the disintegration of the Wilkins Ice Shelf during the winter of 2008. The data presented here are considered a new frontier in physical and biological oceanography, providing a new approach for monitoring sea ice changes and oceanographic conditions in polar oceans. This is especially valid for regions covered by sea ice where traditional instruments deployed by

Parameterizing the competition between homogeneous and heterogeneous freezing in cirrus cloud formation – monodisperse ice nuclei

Directory of Open Access Journals (Sweden)

D. Barahona

2009-01-01

Full Text Available We present a parameterization of cirrus cloud formation that computes the ice crystal number and size distribution under the presence of homogeneous and heterogeneous freezing. The parameterization is very simple to apply and is derived from the analytical solution of the cloud parcel equations, assuming that the ice nuclei population is monodisperse and chemically homogeneous. In addition to the ice distribution, an analytical expression is provided for the limiting ice nuclei number concentration that suppresses ice formation from homogeneous freezing. The parameterization is evaluated against a detailed numerical parcel model, and reproduces numerical simulations over a wide range of conditions with an average error of 6±33%. The parameterization also compares favorably against other formulations that require some form of numerical integration.

Study of ice formation in the porosity of hydraulic binder based materials

International Nuclear Information System (INIS)

Bejaoui, Syriac

2001-01-01

This work concerns the nuclear waste management problematic, and aims at contributing to a better prediction of concrete freeze / thaw behaviour. Ice formation in the porosity of cement pastes and concrete was studied using differential scanning calorimetry and a thermodynamic model. It is shown that ice formation low temperatures in the pores can't be explained considering only interstitial solution under-cooling induced by crystal size restrictions, dissolved chemical elements, and containment pressures. On the other hand, taking into account the nucleation theory and the porosity division degree, three ice formation mechanisms can be defined, near -10, -25 et -40 deg. C. These results allow to explain freeze / thaw behaviour differences between blended and portland cement based materials, as well as, probably, between some high performance concrete, and allow to consider using differential scanning calorimetry as a tool for testing concrete freeze / thaw behaviour. In addition, this study highlights an irreversible shrinkage for cement pastes and concrete induced by freeze / thaw cycles without provision of water, and, on the basis of small angle neutrons scattering measures, the presence of a fractal surface type porosity in high performance cement pastes. (author) [fr

Formaldehyde and tobacco smoke as alkylating agents: the formation of N-methylenvaline in pathologists and in plastic laminate workers.

Science.gov (United States)

Bono, Roberto; Romanazzi, Valeria; Pirro, Valentina; Degan, Raffaella; Pignata, Cristina; Suppo, Elisa; Pazzi, Marco; Vincenti, Marco

2012-01-01

Aim of this study was to investigate the relationships between the concentration of formaldehyde in air and the alkylation of hemoglobin to form a terminal N-methylenvaline residue in three occupationally exposed groups: a) technicians of pathology wards, b) workers of the plastic laminates industry, and c) a control group. All subjects recruited in this study were also tested on their smoking habits. Formaldehyde adsorbed on passive air samplers was quantified by HPLC with UV detection (360 nm), cotinine was quantified by GC-MS. Terminal hemoglobin N-methylenvaline was determined by treating globine under reducing conditions with pentafluorophenyl isothiocyanate to yield a derivative, subsequently detected by GC-MS. One-way analysis of variance was performed to compare among the three groups the biomarkers considered in this study. For air-FA and N-methylenvaline a difference between the three groups was detected (p alkylation to form N-methylenvaline molecular adduct in two occupationally exposed groups of subjects considered in the present study. In comparison with occupational exposition, tobacco smoke proved to have a minor impact on the formation of N-methylenvaline molecular adduct. Copyright © 2011 Elsevier B.V. All rights reserved.

Ice formation and development in aged, wintertime cumulus over the UK : observations and modelling

Science.gov (United States)

Crawford, I.; Bower, K. N.; Choularton, T. W.; Dearden, C.; Crosier, J.; Westbrook, C.; Capes, G.; Coe, H.; Connolly, P.; Dorsey, J. R.; Gallagher, M. W.; Williams, P.; Trembath, J.; Cui, Z.; Blyth, A.

2011-11-01

In-situ high resolution aircraft measurements of cloud microphysical properties were made in coordination with ground based remote sensing observations of Radar and Lidar as part of the Aerosol Properties, PRocesses And InfluenceS on the Earth's climate (APPRAISE) project. A narrow but extensive line (~100 km long) of shallow convective clouds over the southern UK was studied. Cloud top temperatures were observed to be higher than ~-8 °C, but the clouds were seen to consist of supercooled droplets and varying concentrations of ice particles. No ice particles were observed to be falling into the cloud tops from above. Current parameterisations of ice nuclei (IN) numbers predict too few particles will be active as ice nuclei to account for ice particle concentrations at the observed near cloud top temperatures (~-7 °C). The role of biological particles, consistent with concentrations observed near the surface, acting as potential efficient high temperature IN is considered important in this case. It was found that very high concentrations of ice particles (up to 100 L-1) could be produced by powerful secondary ice particle production emphasising the importance of understanding primary ice formation in slightly supercooled clouds. Aircraft penetrations at -3.5 °C, showed peak ice crystal concentrations of up to 100 L-1 which together with the characteristic ice crystal habits observed (generally rimed ice particles and columns) suggested secondary ice production had occurred. To investigate whether the Hallett-Mossop (HM) secondary ice production process could account for these observations, ice splinter production rates were calculated. These calculated rates and observations could only be reconciled provided the constraint that only droplets >24 μm in diameter could lead to splinter production, was relaxed slightly by 2 μm. Model simulations of the case study were also performed with the WRF (Weather, Research and Forecasting) model and ACPIM (Aerosol Cloud and

Fe atoms trapped on graphene as a potential efficient catalyst for room-temperature complete oxidation of formaldehyde: a first-principles investigation

KAUST Repository

Guo, Huimin

2017-03-24

We investigated the oxidation of formaldehyde, one of the major indoor air pollutants, into CO2 and H2O over Fe atoms trapped in defects on graphene by first-principles based calculations. These trapped Fe atoms are not only stable to withstand interference from the reaction environments but are also efficient in catalyzing the reactions between coadsorbed O-2 and formaldehyde. The oxidation of formaldehyde starts with the formation of a peroxide-like intermediate and continues by its dissociation into. eta(1)-OCHO coadsorbed with an OH radical. Then, the adsorbed OCHO undergoes conformational changes and hydride transfer, leading to the formation of H2O and CO2. Subsequent adsorption of O2 or formaldehyde facilitates desorption of H2O and a new reaction cycle initiates. The calculated barriers for formation and dissociation of the peroxide-like intermediate are 0.43 and 0.40 eV, respectively, and those for conformation changes and hydride transfer are 0.47 and 0.13 eV, respectively. These relatively low barriers along the reaction path suggest the potential high catalytic performance of trapped Fe atoms for formaldehyde oxidation.

Fe atoms trapped on graphene as a potential efficient catalyst for room-temperature complete oxidation of formaldehyde: a first-principles investigation

KAUST Repository

Guo, Huimin; Li, Min; Liu, Xin; Meng, Changgong; Linguerri, Roberto; Han, Yu; Chambaud, Gilberte

2017-01-01

We investigated the oxidation of formaldehyde, one of the major indoor air pollutants, into CO2 and H2O over Fe atoms trapped in defects on graphene by first-principles based calculations. These trapped Fe atoms are not only stable to withstand interference from the reaction environments but are also efficient in catalyzing the reactions between coadsorbed O-2 and formaldehyde. The oxidation of formaldehyde starts with the formation of a peroxide-like intermediate and continues by its dissociation into. eta(1)-OCHO coadsorbed with an OH radical. Then, the adsorbed OCHO undergoes conformational changes and hydride transfer, leading to the formation of H2O and CO2. Subsequent adsorption of O2 or formaldehyde facilitates desorption of H2O and a new reaction cycle initiates. The calculated barriers for formation and dissociation of the peroxide-like intermediate are 0.43 and 0.40 eV, respectively, and those for conformation changes and hydride transfer are 0.47 and 0.13 eV, respectively. These relatively low barriers along the reaction path suggest the potential high catalytic performance of trapped Fe atoms for formaldehyde oxidation.

ON THE FORMATION OF DIPEPTIDES IN INTERSTELLAR MODEL ICES

International Nuclear Information System (INIS)

Kaiser, R. I.; Kim, Y. S.; Stockton, A. M.; Jensen, E. C.; Mathies, R. A.

2013-01-01

The hypothesis of an exogenous origin and delivery of biologically important molecules to early Earth presents an alternative route to their terrestrial in situ formation. Dipeptides like Gly-Gly detected in the Murchison meteorite are considered as key molecules in prebiotic chemistry because biofunctional dipeptides present the vital link in the evolutionary transition from prebiotic amino acids to early proteins. However, the processes that could lead to the exogenous abiotic synthesis of dipeptides are unknown. Here, we report the identification of two proteinogenic dipeptides—Gly-Gly and Leu-Ala—formed via electron-irradiation of interstellar model ices followed by annealing the irradiated samples to 300 K. Our results indicate that the radiation-induced, non-enzymatic formation of proteinogenic dipeptides in interstellar ice analogs is facile. Once synthesized and incorporated into the ''building material'' of solar systems, biomolecules at least as complex as dipeptides could have been delivered to habitable planets such as early Earth by meteorites and comets, thus seeding the beginning of life as we know it.

Photoinduced catalytic synthesis of biologically important metabolites from formaldehyde and ammonia under plausible "prebiotic" conditions

Science.gov (United States)

Delidovich, I. V.; Taran, O. P.; Simonov, A. N.; Matvienko, L. G.; Parmon, V. N.

2011-08-01

The article analyzes new and previously reported data on several catalytic and photochemical processes yielding biologically important molecules. UV-irradiation of formaldehyde aqueous solution yields acetaldehyde, glyoxal, glycolaldehyde and glyceraldehyde, which can serve as precursors of more complex biochemically relevant compounds. Photolysis of aqueous solution of acetaldehyde and ammonium nitrate results in formation of alanine and pyruvic acid. Dehydration of glyceraldehyde catalyzed by zeolite HZSM-5-17 yields pyruvaldehyde. Monosaccharides are formed in the course of the phosphate-catalyzed aldol condensation reactions of glycolaldehyde, glyceraldehyde and formaldehyde. The possibility of the direct synthesis of tetroses, keto- and aldo-pentoses from pure formaldehyde due to the combination of the photochemical production of glycolahyde and phosphate-catalyzed carbohydrate chain growth is demonstrated. Erythrulose and 3-pentulose are the main products of such combined synthesis with selectivity up to 10%. Biologically relevant aldotetroses, aldo- and ketopentoses are more resistant to the photochemical destruction owing to the stabilization in hemiacetal cyclic forms. They are formed as products of isomerization of erythrulose and 3-pentulose. The conjugation of the concerned reactions results in a plausible route to the formation of sugars, amino and organic acids from formaldehyde and ammonia under presumed 'prebiotic' conditions.

Inferring Enceladus' ice shell strength and structure from Tiger Stripe formation

Science.gov (United States)

Rhoden, A.; Hurford, T., Jr.; Spitale, J.; Henning, W. G.

2017-12-01

The tiger stripe fractures (TSFs) of Enceladus are four, roughly parallel, linear fractures that correlate with plume sources and high heat flows measured by Cassini. Diurnal variations of plume eruptions along the TSFs strongly suggest that tides modulate the eruptions. Several attempts have been made to infer Enceladus' ice shell structure, and the mechanical process of plume formation, by matching variations in the plumes' eruptive output with tidal stresses for different interior models. Unfortunately, the many, often degenerate, unknowns make these analyses non-unique. Tidal-interior models that best match the observed plume variability imply very low tidal stresses (<14 kPa), much lower than the 1 MPa tensile strength of ice implied by lab experiments or the 100 kPa threshold inferred for Europa's ice. In addition, the interior models that give the best matches are inconsistent with the constraints from observed librations. To gain more insight into the interior structure and rheology of Enceladus and the role of tidal stress in the development of the south polar terrain, we utilize the orientations of the TSFs themselves as observational constraints on tidal-interior models. While the initial formation of the TSFs has previously been attributed to tidal stress, detailed modeling of their formation has not been performed until now. We compute tidal stresses for a suite of rheologically-layered interior models, consistent with Enceladus' observed librations, and apply a variety of failure conditions. We then compare the measured orientations at 6391 points along the TSFs with the predicted orientations from the tidal models. Ultimately, we compute the likelihood of forming the TSFs with tidal stresses for each model and failure condition. We find that tidal stresses are a good match to the observed orientations of the TSFs and likely led to their formation. We also find that the model with the highest likelihood changes depending on the failure criterion

The sensitivities of in cloud and cloud top phase distributions to primary ice formation in ICON-LEM

Science.gov (United States)

Beydoun, H.; Karrer, M.; Tonttila, J.; Hoose, C.

2017-12-01

Mixed phase clouds remain a leading source of uncertainty in our attempt to quantify cloud-climate and aerosol-cloud climate interactions. Nevertheless, recent advances in parametrizing the primary ice formation process, high resolution cloud modelling, and retrievals of cloud phase distributions from satellite data offer an excellent opportunity to conduct closure studies on the sensitivity of the cloud phase to microphysical and dynamical processes. Particularly, the reliability of satellite data to resolve the phase at the top of the cloud provides a promising benchmark to compare model output to. We run large eddy simulations with the new ICOsahedral Non-hydrostatic atmosphere model (ICON) to place bounds on the sensitivity of in cloud and cloud top phase to the primary ice formation process. State of the art primary ice formation parametrizations in the form of the cumulative ice active site density ns are implemented in idealized deep convective cloud simulations. We exploit the ability of ICON-LEM to switch between a two moment microphysics scheme and the newly developed Predicted Particle Properties (P3) scheme by running our simulations in both configurations for comparison. To quantify the sensitivity of cloud phase to primary ice formation, cloud ice content is evaluated against order of magnitude changes in ns at variable convective strengths. Furthermore, we assess differences between in cloud and cloud top phase distributions as well as the potential impact of updraft velocity on the suppression of the Wegener-Bergeron-Findeisen process. The study aims to evaluate our practical understanding of primary ice formation in the context of predicting the structure and evolution of mixed phase clouds.

Modelling snow ice and superimposed ice on landfast sea ice in Kongsfjorden, Svalbard

Directory of Open Access Journals (Sweden)

Caixin Wang

2015-08-01

Full Text Available Snow ice and superimposed ice formation on landfast sea ice in a Svalbard fjord, Kongsfjorden, was investigated with a high-resolution thermodynamic snow and sea-ice model, applying meteorological weather station data as external forcing. The model shows that sea-ice formation occurs both at the ice bottom and at the snow/ice interface. Modelling results indicated that the total snow ice and superimposed ice, which formed at the snow/ice interface, was about 14 cm during the simulation period, accounting for about 15% of the total ice mass and 35% of the total ice growth. Introducing a time-dependent snow density improved the modelled results, and a time-dependent oceanic heat flux parameterization yielded reasonable ice growth at the ice bottom. Model results suggest that weather conditions, in particular air temperature and precipitation, as well as snow thermal properties and surface albedo are the most critical factors for the development of snow ice and superimposed ice in Kongsfjorden. While both warming air and higher precipitation led to increased snow ice and superimposed ice forming in Kongsfjorden in the model runs, the processes were more sensitive to precipitation than to air temperature.

Investigation of HNCO isomer formation in ice mantles by UV and thermal processing: An experimental approach

Energy Technology Data Exchange (ETDEWEB)

Jiménez-Escobar, A.; Giuliano, B. M.; Caro, G. M. Muñoz; Cernicharo, J. [Centro de Astrobiología, INTA-CSIC, Carretera de Ajalvir, km 4, Torrejón de Ardoz, E-28850 Madrid (Spain); Marcelino, N., E-mail: bgiuliano@cab.inta-csic.es [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States)

2014-06-10

Current gas-phase models do not account for the abundances of HNCO isomers detected in various environments, suggesting their formation in icy grain mantles. We attempted to study a formation channel of HNCO and its possible isomers by vacuum-UV photoprocessing of interstellar ice analogs containing H{sub 2}O, NH{sub 3}, CO, HCN, CH{sub 3}OH, CH{sub 4}, and N{sub 2} followed by warm-up under astrophysically relevant conditions. Only the H{sub 2}O:NH{sub 3}:CO and H{sub 2}O:HCN ice mixtures led to the production of HNCO species. The possible isomerization of HNCO to its higher energy tautomers following irradiation or due to ice warm-up has been scrutinized. The photochemistry and thermal chemistry of H{sub 2}O:NH{sub 3}:CO and H{sub 2}O:HCN ices were simulated using the Interstellar Astrochemistry Chamber, a state-of-the-art ultra-high-vacuum setup. The ice was monitored in situ by Fourier transform mid-infrared spectroscopy in transmittance. A quadrupole mass spectrometer detected the desorption of the molecules in the gas phase. UV photoprocessing of H{sub 2}O:NH{sub 3}:CO and H{sub 2}O:HCN ices lead to the formation of OCN{sup –} as a main product in the solid state and a minor amount of HNCO. The second isomer HOCN has been tentatively identified. Despite its low efficiency, the formation of HNCO and the HOCN isomers by UV photoprocessing of realistic simulated ice mantles might explain the observed abundances of these species in photodissociation regions, hot cores, and dark clouds.

Formaldehyde concentration in diagnostic patch testing

DEFF Research Database (Denmark)

Trattner, A; Johansen, J D; Menné, T

1998-01-01

Exposure to formaldehyde is common from both consumer products and industry. The reliability of the patch test is essential for the diagnosis of formaldehyde allergy as it is difficult to suspect from the patient's history. The recommended formaldehyde patch test concentration has been reduced over...

Model simulations with COSMO-SPECS: impact of heterogeneous freezing modes and ice nucleating particle types on ice formation and precipitation in a deep convective cloud

Directory of Open Access Journals (Sweden)

K. Diehl

2018-03-01

Full Text Available In deep convective clouds, heavy rain is often formed involving the ice phase. Simulations were performed using the 3-D cloud resolving model COSMO-SPECS with detailed spectral microphysics including parameterizations of homogeneous and three heterogeneous freezing modes. The initial conditions were selected to result in a deep convective cloud reaching 14 km of altitude with strong updrafts up to 40 m s−1. At such altitudes with corresponding temperatures below −40 °C the major fraction of liquid drops freezes homogeneously. The goal of the present model simulations was to investigate how additional heterogeneous freezing will affect ice formation and precipitation although its contribution to total ice formation may be rather low. In such a situation small perturbations that do not show significant effects at first sight may trigger cloud microphysical responses. Effects of the following small perturbations were studied: (1 additional ice formation via immersion, contact, and deposition modes in comparison to solely homogeneous freezing, (2 contact and deposition freezing in comparison to immersion freezing, and (3 small fractions of biological ice nucleating particles (INPs in comparison to higher fractions of mineral dust INP. The results indicate that the modification of precipitation proceeds via the formation of larger ice particles, which may be supported by direct freezing of larger drops, the growth of pristine ice particles by riming, and by nucleation of larger drops by collisions with pristine ice particles. In comparison to the reference case with homogeneous freezing only, such small perturbations due to additional heterogeneous freezing rather affect the total precipitation amount. It is more likely that the temporal development and the local distribution of precipitation are affected by such perturbations. This results in a gradual increase in precipitation at early cloud stages instead of a strong increase at

Formation of interstellar methanol ice prior to the heavy CO freeze-out stage

Science.gov (United States)

Qasim, D.; Chuang, K.-J.; Fedoseev, G.; Ioppolo, S.; Boogert, A. C. A.; Linnartz, H.

2018-04-01

Context. The formation of methanol (CH3OH) on icy grain mantles during the star formation cycle is mainly associated with the CO freeze-out stage. Yet there are reasons to believe that CH3OH also can form at an earlier period of interstellar ice evolution in CO-poor and H2O-rich ices. Aims: This work focuses on CH3OH formation in a H2O-rich interstellar ice environment following the OH-mediated H-abstraction in the reaction, CH4 + OH. Experimental conditions are systematically varied to constrain the CH3OH formation yield at astronomically relevant temperatures. Methods: CH4, O2, and hydrogen atoms are co-deposited in an ultrahigh vacuum chamber at 10-20 K. OH radicals are generated by the H + O2 surface reaction. Temperature programmed desorption - quadrupole mass spectrometry (TPD-QMS) is used to characterize CH3OH formation, and is complemented with reflection absorption infrared spectroscopy (RAIRS) for CH3OH characterization and quantitation. Results: CH3OH formation is shown to be possible by the sequential surface reaction chain, CH4 + OH → CH3 + H2O and CH3 + OH → CH3OH at 10-20 K. This reaction is enhanced by tunneling, as noted in a recent theoretical investigation Lamberts et al. (2017, A&A, 599, A132). The CH3OH formation yield via the CH4 + OH route versus the CO + H route is approximately 20 times smaller for the laboratory settings studied. The astronomical relevance of the new formation channel investigated here is discussed.

Microfabricated Formaldehyde Gas Sensors

Directory of Open Access Journals (Sweden)

Karen C. Cheung

2009-11-01

Full Text Available Formaldehyde is a volatile organic compound that is widely used in textiles, paper, wood composites, and household materials. Formaldehyde will continuously outgas from manufactured wood products such as furniture, with adverse health effects resulting from prolonged low-level exposure. New, microfabricated sensors for formaldehyde have been developed to meet the need for portable, low-power gas detection. This paper reviews recent work including silicon microhotplates for metal oxide-based detection, enzyme-based electrochemical sensors, and nanowire-based sensors. This paper also investigates the promise of polymer-based sensors for low-temperature, low-power operation.

Bacterial Standing Stock, Activity, and Carbon Production during Formation and Growth of Sea Ice in the Weddell Sea, Antarctica †

OpenAIRE

Grossmann, Sönnke; Dieckmann, Gerhard S.

1994-01-01

Bacterial response to formation and growth of sea ice was investigated during autumn in the northeastern Weddell Sea. Changes in standing stock, activity, and carbon production of bacteria were determined in successive stages of ice development. During initial ice formation, concentrations of bacterial cells, in the order of 1 × 108 to 3 × 108 liter-1, were not enhanced within the ice matrix. This suggests that physical enrichment of bacteria by ice crystals is not effective. Due to low conce...

Formation of formaldehyde adducts in the reactions of DNA and deoxyribonucleosides with alpha-acetates of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), and N-nitrosodimethylamine (NDMA).

Science.gov (United States)

Cheng, Guang; Wang, Mingyao; Upadhyaya, Pramod; Villalta, Peter W; Hecht, Stephen S

2008-03-01

The cytochrome P450-mediated alpha-hydroxylation of the carcinogenic nitrosamines N-nitrosodimethylamine (NDMA, 1), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK, 6a), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL, 6b) produces diazonium ions and formaldehyde. The DNA-binding properties of the diazonium ions have been thoroughly characterized, and there is no doubt that they are critical in cancer induction by these nitrosamines. However, the possibility of additional DNA damage via released formaldehyde has not been reported. In this study, we used acetoxymethylmethylnitrosamine (5), 4-(acetoxymethylnitrosamino)-1-(3-pyridyl)-1-butanone (10a), and 4-(acetoxymethylnitrosamino)-1-(3-pyridyl)-1-butanol (10b) as stable precursors to the alpha-hydroxymethylnitrosamines that would be formed in the metabolism of NDMA, NNK, and NNAL. These alpha-acetates were incubated with calf thymus DNA in the presence of esterase at pH 7.0 and 37 degrees C. The DNA was isolated and enzymatically hydrolyzed to deoxyribonucleosides, and the hydrolysates were analyzed by liquid chromatography-electrospray ionization-mass spectrometry-selected ion monitoring for formaldehyde DNA adducts. Convincing evidence for the formation of the formaldehyde adducts N6-hydroxymethyl-dAdo (11), N4-hydroxymethyl-dCyd (12), N2-hydroxymethyl-dGuo (13), and the cross-links di-(N6-deoxyadenosyl)methane (14), (N6-deoxyadenosyl- N2-deoxyguanosyl)methane (15), and di-(N2-deoxyguanosyl)methane (16) was obtained in these reactions. These results demonstrate that NDMA, NNK, and NNAL have the potential to be bident carcinogens, damaging DNA through the metabolic formation of both diazonium ions and formaldehyde.

Formation and interpretation of eskers beneath retreating ice sheets

Science.gov (United States)

Creyts, T. T.; Hewitt, I.

2017-12-01

The retreat of the ice sheets during the Pleistocene left large and spectacular subglacial features exposed. Understanding these features gives us insight into how the ice sheets retreated, how meltwater influenced retreat, and can help inform our understanding of potential future rates of ice sheet retreat. Among these features, eskers, long sinuous ridges primarily composed of clastic sediments, lack a detailed explanation of how surface melt rates and ice sheet retreat rates influence their growth and spatial distribution. Here, we develop a theory for esker formation based on the initial work of Rothlisberger modified for sediment transport and inclusion of surface meltwater forcing. The primary subglacial ingredients include water flow through subglacial tunnels with the addition of mass balances for sediment transport. We show how eskers when water flow slows below a critical stress for sediment motion. This implies that eskers are deposited in a localized region near the snout of the ice sheet. Our findings suggest that very long eskers form sequentially as the ice front retreats. The position of the esker follows the path of the channel mouth through time, which does not necessarily coincide with the instantaneous route of the feeding channel. However, in most cases, we expect those locations to be similar. The role of surface meltwater and the climatology associated with the forcing is crucial to the lateral spacing of the eskers. We predict that high surface melt rates lead to narrower catchments but that the greater extent of the ablation area means that channels are likely larger. At the same time, for a given channel size (and hence sediment flux), the size of a deposited esker depends on a margin retreat rate. Hence, the size of the eskers is related delicately to the balance between surface melt rates and margin retreat rates. We discuss how our theory can be combined with observed esker distributions to infer the relationship between these two rates

Arctic sea ice melt leads to atmospheric new particle formation.

Science.gov (United States)

Dall Osto, M; Beddows, D C S; Tunved, P; Krejci, R; Ström, J; Hansson, H-C; Yoon, Y J; Park, Ki-Tae; Becagli, S; Udisti, R; Onasch, T; O Dowd, C D; Simó, R; Harrison, Roy M

2017-06-12

Atmospheric new particle formation (NPF) and growth significantly influences climate by supplying new seeds for cloud condensation and brightness. Currently, there is a lack of understanding of whether and how marine biota emissions affect aerosol-cloud-climate interactions in the Arctic. Here, the aerosol population was categorised via cluster analysis of aerosol size distributions taken at Mt Zeppelin (Svalbard) during a 11 year record. The daily temporal occurrence of NPF events likely caused by nucleation in the polar marine boundary layer was quantified annually as 18%, with a peak of 51% during summer months. Air mass trajectory analysis and atmospheric nitrogen and sulphur tracers link these frequent nucleation events to biogenic precursors released by open water and melting sea ice regions. The occurrence of such events across a full decade was anti-correlated with sea ice extent. New particles originating from open water and open pack ice increased the cloud condensation nuclei concentration background by at least ca. 20%, supporting a marine biosphere-climate link through sea ice melt and low altitude clouds that may have contributed to accelerate Arctic warming. Our results prompt a better representation of biogenic aerosol sources in Arctic climate models.

Formaldehyde Crosses the Human Placenta and Affects Human Trophoblast Differentiation and Hormonal Functions.

Directory of Open Access Journals (Sweden)

Guillaume Pidoux

Full Text Available The chorionic villus of the human placenta is the source of specific endocrine functions and nutrient exchanges. These activities are ensured by the syncytiotrophobast (ST, which bathes in maternal blood. The ST arises and regenerates throughout pregnancy by fusion of underlying cytotrophoblasts (CT. Any anomaly of ST formation or regeneration can affect pregnancy outcome and fetal growth. Because of its direct interaction with maternal blood, the ST is sensitive to drugs, pollutants and xenohormones. Ex vivo assays of perfused cotyledon show that formaldehyde, a common pollutant present in furniture, paint and plastics, can accumulate in the human placenta and cross to the fetal compartment. By means of RT-qPCR, immunoblot and immunocytochemistry experiments, we demonstrate in vitro that formaldehyde exerts endocrine toxicity on human trophoblasts, including a decrease in the production of protein hormones of pregnancy. In addition, formaldehyde exposure triggered human trophoblast fusion by upregulating syncitin-1 receptor expression (ASC-type amino-acid transporter 2: ASCT2. Moreover, we show that formaldehyde-exposed trophoblasts present an altered redox status associated with oxidative stress, and an increase in ASCT2 expression intended to compensate for this stress. Finally, we demonstrate that the adverse effects of formaldehyde on trophoblast differentiation and fusion are reversed by N-acetyl-L-cysteine (Nac, an antioxidant.

Quantification of free formaldehyde in carrageenan and processed Eucheuma seaweed using high-performance liquid chromatography.

Science.gov (United States)

Hornshøj, Bettina Høj; Kobbelgaard, Sara; Blakemore, William R; Stapelfeldt, Henrik; Bixler, Harris J; Klinger, Markus

2015-01-01

In 2010 the European Commission placed a limit on the amount of free formaldehyde in carrageenan and processed Eucheuma seaweed (PES) of 5 mg kg(-1). Formaldehyde is not used in carrageenan and PES processing and accordingly one would not expect free formaldehyde to be present in carrageenan and PES. However, surprisingly high levels up to 10 mg kg(-1) have been found using the generally accepted AOAC and Hach tests. These findings are, per proposed reaction pathways, likely due to the formation of formaldehyde when sulphated galactose, the backbone of carrageenan, is hydrolysed with the strong acid used in these conventional tests. In order to minimise the risk of false-positives, which may lead to regulatory non-compliance, a new high-performance liquid chromatography (HPLC) method has been developed. Initially, carrageenan or PES is extracted with 2-propanol and subsequently reacted with 2,4-dinitrophenylhydrazine (DNPH) to form the chromophore formaldehyde-DNPH, which is finally quantified by reversed-phase HPLC with ultraviolet light detection at 355 nm. This method has been found to have a limit of detection of 0.05 mg kg(-1) and a limit of quantification of 0.2 mg kg(-1). Recoveries from samples spiked with known quantities of formaldehyde were 95-107%. Using this more specific technique, 20 samples of carrageenan and PES were tested for formaldehyde. Only one sample had a detectable content of formaldehyde (0.40 mg kg(-1)), thus demonstrating that the formaldehyde content of commercial carrageenan and PES products are well below the European Commission maximum limit of 5 mg kg(-1).

Novel Reaction of N,N'-Bisarylmethanediamines with Formaldehyde. Synthesis of Some New 1,3,5-Triaryl-1,3,5-hexahydrotriazines

Directory of Open Access Journals (Sweden)

Abolfazl Olyaei

2006-07-01

Full Text Available The acid-catalyzed cyclocondensation of N,N'-bisaryl (aryl = 2-pyrimidinyl, 2- pyrazinyl and 4-nitrophenyl methanediamines 5a-c with aqueous formaldehyde in refluxing acetonitrile leads to the formation of the corresponding 1,3,5-triaryl-1,3,5-hexa- hydrotriazines 6a-c. The stoichiometric reactions of 2-aminopyrimidine and 2-amino- pyrazine with aqueous formaldehyde in acetonitrile under reflux conditions also afforded 6a and 6b, respectively. Treatment of 2-aminopyrimidine with aqueous formaldehyde in a 3:2 ratio yielded N,N',N"-tris(2-pyrimidinyldimethylenetriamine (7a as a sole product, which upon subsequent reaction with formaldehyde also afforded 6a. The reaction of N,N'-biphenylmethanediamine with formaldehyde was also investigated.

Development of a Capacitive Ice Sensor to Measure Ice Growth in Real Time

Directory of Open Access Journals (Sweden)

Xiang Zhi

2015-03-01

Full Text Available This paper presents the development of the capacitive sensor to measure the growth of ice on a fuel pipe surface in real time. The ice sensor consists of pairs of electrodes to detect the change in capacitance and a thermocouple temperature sensor to examine the ice formation situation. In addition, an environmental chamber was specially designed to control the humidity and temperature to simulate the ice formation conditions. From the humidity, a water film is formed on the ice sensor, which results in an increase in capacitance. Ice nucleation occurs, followed by the rapid formation of frost ice that decreases the capacitance suddenly. The capacitance is saturated. The developed ice sensor explains the ice growth providing information about the icing temperature in real time.

Development of a capacitive ice sensor to measure ice growth in real time.

Science.gov (United States)

Zhi, Xiang; Cho, Hyo Chang; Wang, Bo; Ahn, Cheol Hee; Moon, Hyeong Soon; Go, Jeung Sang

2015-03-19

This paper presents the development of the capacitive sensor to measure the growth of ice on a fuel pipe surface in real time. The ice sensor consists of pairs of electrodes to detect the change in capacitance and a thermocouple temperature sensor to examine the ice formation situation. In addition, an environmental chamber was specially designed to control the humidity and temperature to simulate the ice formation conditions. From the humidity, a water film is formed on the ice sensor, which results in an increase in capacitance. Ice nucleation occurs, followed by the rapid formation of frost ice that decreases the capacitance suddenly. The capacitance is saturated. The developed ice sensor explains the ice growth providing information about the icing temperature in real time.

Assessment of lipid peroxidation and p53 as a biomarker of carcinogenesis among workers exposed to formaldehyde in the cosmetic industry.

Science.gov (United States)

Attia, Dalia; Mansour, Neveen; Taha, Fatma; Seif El Dein, Aisha

2016-06-01

Despite the wide use of cosmetic products, they exert a number of health effects on tissues ranging from irritation to cancer. Our study aimed at assessing the effect of formaldehyde on lipid peroxidation and verifying the susceptibility to carcinogenesis using p53 as a biomarker among workers exposed to formaldehyde in cosmetic industry. Our entire exposed group (n = 40) and the controls (n = 20) were subjected to estimation of formate in urine, serum malondialdehyde (MDA), and p53. Also, complete blood picture, liver, and kidney function tests were carried out. The study revealed significant increase in the levels of formate, MDA, and p53 in the exposed group compared with their control group. Our results showed that workers in cosmetic industry had significant exposure to formaldehyde. Furthermore, the study pointed to the negative impact of formaldehyde as a cause of oxidative stress and suspicious carcinogen. © The Author(s) 2014.

Possible Mechanisms for Turbofan Engine Ice Crystal Icing at High Altitude

Science.gov (United States)

Tsao, Jen-Ching; Struk, Peter M.; Oliver, Michael J.

2016-01-01

A thermodynamic model is presented to describe possible mechanisms of ice formation on unheated surfaces inside a turbofan engine compression system from fully glaciated ice crystal clouds often formed at high altitude near deep convective weather systems. It is shown from the analysis that generally there could be two distinct types of ice formation: (1) when the "surface freezing fraction" is in the range of 0 to 1, dominated by the freezing of water melt from fully or partially melted ice crystals, the ice structure is formed from accretion with strong adhesion to the surface, and (2) when the "surface melting fraction" is the range of 0 to 1, dominated by the further melting of ice crystals, the ice structure is formed from accumulation of un-melted ice crystals with relatively weak bonding to the surface. The model captures important qualitative trends of the fundamental ice-crystal icing phenomenon reported earlier (Refs. 1 and 2) from the research collaboration work by NASA and the National Research Council (NRC) of Canada. Further, preliminary analysis of test data from the 2013 full scale turbofan engine ice crystal icing test (Ref. 3) conducted in the NASA Glenn Propulsion Systems Laboratory (PSL) has also suggested that (1) both types of ice formation occurred during the test, and (2) the model has captured some important qualitative trend of turning on (or off) the ice crystal ice formation process in the tested engine low pressure compressor (LPC) targeted area under different icing conditions that ultimately would lead to (or suppress) an engine core roll back (RB) event.

The effects of sub-ice-shelf melting on dense shelf water formation and export in idealized simulations of Antarctic margins

Science.gov (United States)

Marques, Gustavo; Stern, Alon; Harrison, Matthew; Sergienko, Olga; Hallberg, Robert

2017-04-01

Dense shelf water (DSW) is formed in coastal polynyas around Antarctica as a result of intense cooling and brine rejection. A fraction of this water reaches ice shelves cavities and is modified due to interactions with sub-ice-shelf melt water. This modified water mass contributes to the formation of Antarctic Bottom Water, and consequently, influences the large-scale ocean circulation. Here, we investigate the role of sub-ice-shelf melting in the formation and export of DSW using idealized simulations with an isopycnal ocean model (MOM6) coupled with a sea ice model (SIS2) and a thermodynamic active ice shelf. A set of experiments is conducted with variable horizontal grid resolutions (0.5, 1.0 and 2.0 km), ice shelf geometries and atmospheric forcing. In all simulations DSW is spontaneously formed in coastal polynyas due to the combined effect of the imposed atmospheric forcing and the ocean state. Our results show that sub-ice-shelf melting can significantly change the rate of dense shelf water outflows, highlighting the importance of this process to correctly represent bottom water formation.

Greenland meltwater storage in firn limited by near-surface ice formation

DEFF Research Database (Denmark)

Machguth, Horst; MacFerrin, Mike; van As, Dirk

2016-01-01

above sea level), firn has undergone substantial densification, while at lower elevations, where melt is most abundant, porous firn has lost most of its capability to retain meltwater. Here, the formation of near-surface ice layers renders deep pore space difficult to access, forcing meltwater to enter...

Emission of formaldehyde from furniture

DEFF Research Database (Denmark)

Andersen, Helle Vibeke; Klinke, Helene B.; Funch, Lis Winther

The emission of formaldehyde from 20 pieces of furniture, representing a variety of types, was measured in climate chambers. Most tests show low emissions but certain scenarios of furnishing, including furniture with large surface areas in relation to room volume can emit formaldehyde resulting...

On the formation of niacin (vitamin B3) and pyridine carboxylic acids in interstellar model ices

Energy Technology Data Exchange (ETDEWEB)

McMurtry, Brandon M.; Turner, Andrew M.; Saito, Sean E.J.; Kaiser, Ralf I. [W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, Hawaii, HI 96822 (United States); Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii, HI 96822 (United States)

2016-06-15

The formation of pyridine carboxylic acids in interstellar ice grains was simulated by electron exposures of binary pyridine (C{sub 5}H{sub 5}N)-carbon dioxide (CO{sub 2}) ice mixtures at 10 K under contamination-free ultrahigh vacuum conditions. Chemical processing of the pristine ice and subsequent warm-up phase was monitored on line and in situ via Fourier transform infrared spectroscopy to probe for the formation of new radiation induced species. In the infrared spectra of the irradiated ice, bands assigned to nicotinic acid (niacin; vitamin B3; m-C{sub 5}H{sub 4}NCOOH) along with 2,3-, 2,5-, 3,4-, and 3,5-pyridine dicarboxylic acid (C{sub 5}H{sub 3}N(COOH){sub 2}) were unambiguously identified along with the hydroxycarbonyl (HOCO) radical. Our study suggests that the reactive pathway responsible for pyridine carboxylic acids formation involves a HOCO intermediate, which forms through the reaction of suprathermal hydrogen ejected from pyridine with carbon dioxide. The newly formed pyridinyl radical may then undergo radical–radical recombination with a hydroxycarbonyl radical to form a pyridine carboxylic acid.

Cloudy with a Chance of Ice: The Stratification of Titan's Vernal Ponds and Formation of Ethane Ice

Science.gov (United States)

Soderblom, J. M.; Steckloff, J. K.

2017-12-01

Cassini ISS observations revealed regions on Saturn's moon Titan that become significantly darker (lower albedo) following storm events [1]. These regions are observed to be topographically low [2], indicating that liquid (predominantly methane-ethane-nitrogen) is pooling on Titan after these storm events. These dark ponds, however, are then observed to significantly brighten (higher albedo relative to pre-storm albedo), before fading to their pre-storm albedos [2-3]. We interpret these data to indicate ethane ice formation, which cools from evaporation of methane. The formation of ethane ices results from a unique sequence of thermophysical and thermochemical phenomena. Initially, the methane in the mixture evaporates, cooling the pond. Nitrogen, dissolved primarily in the methane, exsolves, further cooling the liquid. However, because nitrogen is significantly more soluble in cooler methane-hydrocarbon mixtures, relatively more methane than nitrogen leaves the fluid, increasing the relative fraction of nitrogen. This increased nitrogen fraction increases the density of the liquid, as nitrogen is significantly denser than methane or ethane (pure ethane's density is intermediate to that of methane and nitrogen). At around 85 K the mixture is as dense as pure liquid ethane. Thus, further evaporative methane loss and cooling at the pond's surface leads to a chemical stratification, with an increasingly ethane rich epilimnion (surface layer) overlying a methane rich hypolimnion (subsurface layer). Further evaporation of methane from the ethane-rich epilimnion drives its temperature and composition toward the methane-ethane-nitrogen liquidus curve, causing pure ethane ice to precipitate out of solution and settle to the bottom of the pool. This settling would obscure the ethane ice from Cassini VIMS and ISS, which would instead continue to appear as a dark pond on the surface. As the ethane precipitates out completely, a binary methane-nitrogen liquid mixture remains

Assimilation of formaldehyde and other C1-compounds by Gliocladium deliquescens and Paecilomyces varioti

International Nuclear Information System (INIS)

Sakaguchi, Kenji; Kurane, Ryuichiro; Murata, Machiko

1975-01-01

Two fungi were isolated from soil which grew on 0.1--0.2% formaldehyde as the sole carbon source, and identified as Gliocladium deliquescens and Paecilomyces varioti. Both the strains could grow on 5% methanol and 5% Na-formate, while the former could grow even on 7% methanol. Metabolic pathways were traced through two dimensional paper chromatography and autoradiographic techniques using 14 C-formaldehyde, 14 C-methanol or 14 C-CO 2 as substrates. The intracellular metabolites were persued and their quantitative variation with time was measured. Along with the fact that serine and malate appeared in the earlier time, then appeared organic acids and amino acids belonging to TCA cycle, and the fact that hydroxy-pyruvate reductase and phosphoenolpyruvate carboxylase activities were much stronger in methanol culture than in ethanol culture, it was concluded that the two fungi followed the serine pathway in assimilating C 1 -compounds. Oxidation enzymes of methanol and formaldehyde were also studied, and an oxidizing system was found besides usual NAD linked methanol or formaldehyde dehydrogenases. (auth.)

Identification of formaldehyde-responsive genes by suppression subtractive hybridization

International Nuclear Information System (INIS)

Lee, Min-Ho; Kim, Young-Ae; Na, Tae-Young; Kim, Sung-Hye; Shin, Young Kee; Lee, Byung-Hoon; Shin, Ho-Sang; Lee, Mi-Ock

2008-01-01

Formaldehyde is frequently used in indoor household and occupational environments. Inhalation of formaldehyde invokes an inflammatory response, including a variety of allergic signs and symptoms. Therefore, formaldehyde has been considered as the most prevalent cause of sick building syndrome, which has become a major social problem, especially in developing urban areas. Further formaldehyde is classified as a genotoxicant in the respiratory tract of rats and humans. To better understand the molecular mechanisms involved in formaldehyde intoxication, we sought differentially regulated genes by formaldehyde exposure to Hs 680.Tr human trachea cells, using polymerase chain reaction (PCR)-based suppression subtractive hybridization. We identified 27 different formaldehyde-inducible genes, including those coding for the major histocompatibility complex, class IA, calcyclin, glutathione S-transferase pi, mouse double minute 2 (MDM2), platelet-derived growth factor receptor alpha, and which are known to be associated with cell proliferation and differentiation, immunity and inflammation, and detoxification. Induction of these genes by formaldehyde treatment was confirmed by reverse transcription PCR and western blot analysis. Further, the expression of calcyclin, glutathione S-transferase pi, PDGFRA and MDM2 were significantly induced in the tracheal epithelium of Sprague Dawley rats after formaldehyde inhalation. Our results suggest that the elevated levels of these genes may be associated with the formaldehyde-induced toxicity, and that they deserve evaluation as potential biomarkers for formaldehyde intoxication

Formaldehyde-induced mutations in Drosophila melanogaster in dependence of the presence of acids

Energy Technology Data Exchange (ETDEWEB)

Stumm-Tegethoff, B F.A.

1969-01-01

The mutagenic activity of various combinations of formaldehyde, formic acid, acetic acid and hydrochloric acid was investigated by a sex-linked lethal test. All combinations were mutagenic and showed a mutation pattern from which it is concluded that in feeding experiments spermatocytes I are especially sensitive to the pairs of chemicals tested. In vapour experiments all germ cell stages were found to be susceptible. The presence of volatile acids was found to be necessary for the mutagenic activity of formaldehyde in the vapour state. Mutagenic effects were also observed in larval feeding experiments, in which only these acids were added to the medium. Experiments with stabilized pH at 7.5 did not show a significant mutagenic effect of formaldehyde. It is postulated that the tested agents are catalase inhibitors, which promote the formation of peroxides or free radicals which interfere with DNA replication, thus producing mutations.

Analysis of the Effect of Water Activity on Ice Formation Using a New Theory of Nucleation

Science.gov (United States)

Barahona, Donifan

2013-01-01

In this work a new theory of nucleation is developed and used to investigate the effect of water activity on the formation of ice within super-cooled droplets. The new theory is based on a novel concept where the interface is assumed to be made of liquid molecules trapped by the solid matrix. Using this concept new expressions are developed for the critical ice germ size and the nucleation work, with explicit dependencies on temperature and water activity. However unlike previous approaches, the new theory does not depend on the interfacial tension between liquid and ice. Comparison against experimental results shows that the new theory is able to reproduce the observed effect of water activity on nucleation rate and freezing temperature. It allows for the first time a theoretical derivation of the constant shift in water activity between melting and nucleation. The new theory offers a consistent thermodynamic view of ice nucleation, simple enough to be applied in atmospheric models of cloud formation.

Methane hydrate synthesis from ice: Influence of pressurization and ethanol on optimizing formation rates and hydrate yield

Science.gov (United States)

Chen, Po-Chun.; Huang, Wuu-Liang; Stern, Laura A.

2010-01-01

Polycrystalline methane gas hydrate (MGH) was synthesized using an ice-seeding method to investigate the influence of pressurization and ethanol on the hydrate formation rate and gas yield of the resulting samples. When the reactor is pressurized with CH4 gas without external heating, methane hydrate can be formed from ice grains with yields up to 25% under otherwise static conditions. The rapid temperature rise caused by pressurization partially melts the granular ice, which reacts with methane to form hydrate rinds around the ice grains. The heat generated by the exothermic reaction of methane hydrate formation buffers the sample temperature near the melting point of ice for enough time to allow for continuous hydrate growth at high rates. Surprisingly, faster rates and higher yields of methane hydrate were found in runs with lower initial temperatures, slower rates of pressurization, higher porosity of the granular ice samples, or mixtures with sediments. The addition of ethanol also dramatically enhanced the formation of polycrystalline MGH. This study demonstrates that polycrystalline MGH with varied physical properties suitable for different laboratory tests can be manufactured by controlling synthesis procedures or parameters. Subsequent dissociation experiments using a gas collection apparatus and flowmeter confirmed high methane saturation (CH 4·2O, with n = 5.82 ± 0.03) in the MGH. Dissociation rates of the various samples synthesized at diverse conditions may be fitted to different rate laws, including zero and first order.

The microcapsule-type formaldehyde scavenger: the preparation and the application in urea-formaldehyde adhesives.

Science.gov (United States)

Duan, Hongyun; Qiu, Teng; Guo, Longhai; Ye, Jun; Li, Xiaoyu

2015-08-15

The limitation and regulation of formaldehyde emissions (FE) now shows great importance in wood-based materials such as plywood and particle board manufactured for building and furnishing materials. The widely used formaldehyde-based adhesives are one of the main sources of FE from the wood products. In this work, a new kind of long-term effective formaldehyde scavenger in the microcapsule form was prepared by using an intra-liquid desiccation method. The characterizations of the capsule (UC) were performed including the morphologies, the yields, the loading efficiency as well as its sustained-release of urea in aqueous conditions. The prepared UC could be integrated in urea-formaldehyde resins by simply physical blending, and the mixtures were available to be applied as the adhesives for the manufacture of plywood. The bonding strength (BS) and the FE of the bonded plywood in both short (3h) and long (12 week) period were evaluated in detail. It was found that the FE profile of the plywood behaved following a duple exponential law within 12 week. The addition of UC in the adhesive can effectively depress the FE of the plywood not only in a short period after preparation but also in a long-term period during its practical application. The slow released urea would continuously suppress the emission of toxic formaldehyde in a sustained manner without obviously deteriorating on the BS of the adhesives. Copyright © 2015 Elsevier B.V. All rights reserved.

Simple, rapid method for the preparation of isotopically labeled formaldehyde

Science.gov (United States)

Hooker, Jacob Matthew [Port Jefferson, NY; Schonberger, Matthias [Mains, DE; Schieferstein, Hanno [Aabergen, DE; Fowler, Joanna S [Bellport, NY

2011-10-04

Isotopically labeled formaldehyde (*C.sup..sctn.H.sub.2O) is prepared from labeled methyl iodide (*C.sup..sctn.H.sub.3I) by reaction with an oxygen nucleophile having a pendant leaving group. The mild and efficient reaction conditions result in good yields of *C.sup..sctn.H.sub.2O with little or no *C isotopic dilution. The simple, efficient production of .sup.11CH.sub.2O is described. The use of the .sup.11CH.sub.2O for the formation of positron emission tomography tracer compounds is described. The reaction can be incorporated into automated equipment available to radiochemistry laboratories. The isotopically labeled formaldehyde can be used in a variety of reactions to provide radiotracer compounds for imaging studies as well as for scintillation counting and autoradiography.

Canadian Ice Service Arctic Regional Sea Ice Charts in SIGRID-3 Format

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Canadian Ice Service (CIS) produces digital Arctic regional sea ice charts for marine navigation, climate research, and input to the Global Digital Sea Ice Data...

Solid-State Photochemistry as a Formation Mechanism for Titan's Stratospheric C4N2 Ice Clouds

Science.gov (United States)

Anderson, C. M.; Samuelson, R. E.; Yung, Y. L.; McLain, J. L.

2016-01-01

We propose that C4N2 ice clouds observed in Titan's springtime polar stratosphere arise due to solid-state photochemistry occurring within extant ice cloud particles of HCN-HC3N mixtures. This formation process resembles the halogen-induced ice particle surface chemistry that leads to condensed nitric acid trihydrate (NAT) particles and ozone depletion in Earth's polar stratosphere. As our analysis of the Cassini Composite Infrared Spectrometer 478 per centimeter ice emission feature demonstrates, this solid-state photochemistry mechanism eliminates the need for the relatively high C4N2 saturation vapor pressures required (even though they are not observed) when the ice is produced through the usual procedure of direct condensation from the vapor.

ON THE FORMATION OF BENZOIC ACID AND HIGHER-ORDER BENZENE CARBOXYLIC ACIDS IN INTERSTELLAR MODEL ICE GRAINS

Energy Technology Data Exchange (ETDEWEB)

McMurtry, Brandon M.; Saito, Sean E. J.; Turner, Andrew M.; Chakravarty, Harish K.; Kaiser, Ralf I. [W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, HI 96822 (United States)

2016-11-10

With a binary ice mixture of benzene (C{sub 6}H{sub 6}) and carbon dioxide (CO{sub 2}) at 10 K under contamination-free ultrahigh vacuum conditions, the formation of benzene carboxylic acids in interstellar ice grains was studied. Fourier transform infrared spectroscopy was used to probe for the formation of new species during the chemical processing of the ice mixture and during the following temperature-programmed desorption. Newly formed benzene carboxylic acid species, i.e., benzoic acid, as well as meta - and para -benzene dicarboxylic acid, were assigned using newly emerging bands in the infrared spectrum; a reaction mechanism, along with rate constants, was proposed utilizing the kinetic fitting of the coupled differential equations.

Aerosolization, Chemical Characterization, Hygroscopicity and Ice Formation of Marine Biogenic Particles

Science.gov (United States)

Alpert, P. A.; Radway, J.; Kilthau, W.; Bothe, D.; Knopf, D. A.; Aller, J. Y.

2013-12-01

The oceans cover the majority of the earth's surface, host nearly half the total global primary productivity and are a major source of atmospheric aerosol particles. However, effects of biological activity on sea spray generation and composition, and subsequent cloud formation are not well understood. Our goal is to elucidate these effects which will be particularly important over nutrient rich seas, where microorganisms can reach concentrations of 10^9 per mL and along with transparent exopolymer particles (TEP) can become aerosolized. Here we report the results of mesocosm experiments in which bubbles were generated by two methods, either recirculating impinging water jets or glass frits, in natural or artificial seawater containing bacteria and unialgal cultures of three representative phytoplankton species, Thalassiosira pseudonana, Emiliania huxleyi, and Nannochloris atomus. Over time we followed the size distribution of aerosolized particles as well as their hygroscopicity, heterogeneous ice nucleation potential, and individual physical-chemical characteristics. Numbers of cells and the mass of dissolved and particulate organic carbon (DOC, POC), TEP (which includes polysaccharide-containing microgels and nanogels >0.4 μm in diameter) were determined in the bulk water, the surface microlayer, and aerosolized material. Aerosolized particles were also impacted onto substrates for ice nucleation and water uptake experiments, elemental analysis using computer controlled scanning electron microscopy and energy dispersive analysis of X-rays (CCSEM/EDX), and determination of carbon bonding with scanning transmission X-ray microscopy and near-edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). Regardless of bubble generation method, the overall concentration of aerosol particles, TEP, POC and DOC increased as concentrations of bacterial and phytoplankton cells increased, stabilized, and subsequently declined. Particles cloud formation and potential

Quantification of atmospheric formaldehyde by infrared absorption spectroscopy

Science.gov (United States)

Hoffnagle, John; Fleck, Derek; Rella, Chris; Kim-Hak, David

2017-04-01

Formaldehyde is a toxic, carcinogenic compound that can contaminate ambient air as a result of combustion or outgassing of commercial products such as adhesives used to fabricate plywood and to affix indoor carpeting. Like many small molecules, formaldehyde has an infrared absorption spectrum exhibiting bands of ro-vibrational transitions that are well resolved at low pressure and therefore well suited for optical analysis of formaldehyde concentration. We describe progress in applying cavity ring-down spectroscopy of the 2v5 band (the first overtone of the asymmetric C-H stretch, origin at 1770 nm) to the quantitative analysis of formaldehyde concentration in ambient air. Preliminary results suggest that a sensitivity of 1-2 ppb in a measurement interval of a few seconds, and 0.1-0.2 ppb in a few minutes, should be achievable with a compact, robust, and field-deployable instrument. Finally, we note that recent satellites monitoring snapshots of formaldehyde columns give insights into global formaldehyde production, migration and lifetime. The ability to monitor formaldehyde with a small and portable analyzer has the potential to aid in validation of these snapshots and to provide complementary data to show vertical dispersions with high spatial accuracy.

Bacterial Standing Stock, Activity, and Carbon Production during Formation and Growth of Sea Ice in the Weddell Sea, Antarctica.

Science.gov (United States)

Grossmann, S; Dieckmann, G S

1994-08-01

Bacterial response to formation and growth of sea ice was investigated during autumn in the northeastern Weddell Sea. Changes in standing stock, activity, and carbon production of bacteria were determined in successive stages of ice development. During initial ice formation, concentrations of bacterial cells, in the order of 1 x 10 to 3 x 10 liter, were not enhanced within the ice matrix. This suggests that physical enrichment of bacteria by ice crystals is not effective. Due to low concentrations of phytoplankton in the water column during freezing, incorporation of bacteria into newly formed ice via attachment to algal cells or aggregates was not recorded in this study. As soon as the ice had formed, the general metabolic activity of bacterial populations was strongly suppressed. Furthermore, the ratio of [H]leucine incorporation into proteins to [H]thymidine incorporation into DNA changed during ice growth. In thick pack ice, bacterial activity recovered and growth rates up to 0.6 day indicated actively dividing populations. However, biomass-specific utilization of organic compounds remained lower than in open water. Bacterial concentrations of up to 2.8 x 10 cells liter along with considerably enlarged cell volumes accumulated within thick pack ice, suggesting reduced mortality rates of bacteria within the small brine pores. In the course of ice development, bacterial carbon production increased from about 0.01 to 0.4 mug of C liter h. In thick ice, bacterial secondary production exceeded primary production of microalgae.

Heat transfer analysis and effects of feeding tubes arrangement, falling film behavior and backsplash on ice formation around horizontal tubes bundles

International Nuclear Information System (INIS)

Sait, Hani Hussain

2013-01-01

Highlights: • Ice shape around the tubes. • Effects of accumulation of ice around the tubes. • Effects of parallel and series tubes arrangements. • Effects of ice accumulated around the tube surfaces. • Effects of backsplash on ice formation. - Abstract: Excessive electrical load has recently get a lot of attention from electric companies specially in hot countries like Saudi Arabia, where air-conditioning load represents about 75% from the total electrical load. Energy storage by freezing is one of the methods that used to tackle this issue. Ice is formed around horizontal cold tubes that are subjected to falling film of water. Ice quantity is measured, photographed and studied. In this studied the coolant inside the tubes flows in series tube arrangement. The results are compared with previous study in which parallel arrangement was used. In addition the falling film behavior and the resulted backsplash are also investigated. A mathematical model to predict ice formation around the tube is proposed. Comparison of the results of the model with that of the experiments showed that the agreement between the two is acceptable. The results also show a quite reasonable quantity of ice is formed in a short time and the series arrangement is more efficient than parallel one. The falling film shapes and its backsplash has also affected the ice formation

Effect of ice formation and streamflow on salmon incubation habitat in the lower Bradley River, Alaska

Science.gov (United States)

Rickman, R.L.

1996-01-01

A minimum flow of 40 cubic feet per second is required in the lower Bradley River, near Homer, Alaska, from November 2 to April 30 to ensure adequate salmon egg incubation habitat. The study that determined this minimum flow did not account for the effects of ice formation on habitat. An investigation was made during periods of ice formation. Hydraulic properties and field water-quality data were measured in winter only from March 1993 to April 1995 at six transects in the lower Bradley River. Discharge in the lower Bradley River ranged from 42.6 to 73.0 cubic feet per second (average 57 cubic feet per second) with ice conditions ranging from near ice free to 100 percent ice cover. Stream water velocity and depth were adequate for habitat protection for all ice conditions and discharges. No relation was found between percent ice cover and mean velocity and depth for any given discharge and no trends were found with changes in discharge for a given ice condition. Velocity distribution within each transect varied significantly from one sampling period to the next. Mean depth and velocity at flows of 40 cubic feet per second or less could not be predicted. No consistent relation was found between the amount of wetted perimeter and percent ice cover. Intragravel-water temperature was slightly warmer than surface-water temperature. Surface and intragravel-water dissolved-oxygen levels were adequate for all flows and ice conditions. No apparent relation was found between dissolved-oxygen levels and streamflow or ice conditions. Excellent oxygen exchange was indicated throughout the study reach. Stranding potential of salmon fry was found to be low throughout the study reach. The limiting factors for determining the minimal acceptable flow limit appear to be stream-water velocity and depth, although specific limits could not be estimated because of the high flows that occurred during this study.

Ice Lens Formation, Frost Heave, Thin Films, and the Importance of the Polar H2O Reservoir at High Obliquity

Science.gov (United States)

Zent, A. P.; Sizemore, H. G.; Rempel, A. W.

2011-01-01

Several lines of evidence indicate that the volume of shallow ground ice in the martian high latitudes exceeds the pore volume of the host regolith. Boynton et al. found an optimal fit to the Mars Odyssey Gamma Ray Spectrometer (GRS) data at the Phoenix landing site by modeling a buried layer of 50-75% ice by mass (up to 90% ice by volume). Thermal and optical observations of recent impact craters in the northern hemisphere have revealed nearly pure ice. Ice deposits containing only 1-2% soil by volume were excavaged by Phoenix. One hypothesis for the origin of this excess ice is that it developed in situ by a mechanism analogous to the formation of terrestrial ice lenses and needle ice. Problematically, terrestrial soil-ice segregation is driven by freeze/thaw cycling and the movement of bulk water, neither of which are expected to have occurred in the geologically recent past on Mars. If however ice lens formation is possible at temperatures less than 273 K, there are possible implications for the habitability of Mars permafrost, since the same thin films of unfrozen water that lead to ice segregation are used by terrestrial psychrophiles to metaboluze and grow down to temperatures of at least 258 K.

Hardness evaluation of cured urea-formaldehyde resins with different formaldehyde/urea mole ratios using nanoindentation method

Science.gov (United States)

Byung-Dae Park; Charles R. Frihart; Yan Yu; Adya P. Singh

2013-01-01

To understand the influence of formaldehyde/urea (F/U) mole ratio on the properties of urea–formaldehyde (UF) resins, this study investigated hardness of cured UF resins with different F/U mole ratios using a nanoindentation method. The traditional Brinell hardness (HB) method was also used...

Observation of ice sheet formation on methane and ethane gas hydrates using a scanning confocal microscopy

Energy Technology Data Exchange (ETDEWEB)

Nagao, J.; Shimomura, N.; Ebinuma, T.; Narita, H. [National Inst. of Advanced Industrial Science and Technology, Toyohira, Sapporo (Japan). Methane Hydrate Research Lab.

2008-07-01

Interest in gas hydrates has increased in recent years due to the discovery of large deposits under the ocean floor and in permafrost regions. Natural gas hydrates, including methane, is expected to become a new energy source and a medium for energy storage and transportation. Gas hydrates consist of an open network of water molecules that are hydrogen-bonded in a similar manner to ice. Gas molecules are interstitially engaged under high pressures and low temperatures. Although the dissociation temperature of methane hydrate under atmospheric pressure is about 193 K, studies have shown that methane hydrate can be stored at atmospheric pressure and 267 K for 2 years. Because of this phenomenon, known as self-preservation, transportation and storage of methane hydrate can occur at temperature conditions milder than those for liquefied methane gas at atmospheric pressure. This study examined the surface changes of methane and ethane hydrates during dissociation using an optical microscope and confocal scanning microscope (CSM). This paper reported on the results when the atmospheric gas pressure was decreased. Ice sheets formed on the surfaces of methane and ethane gas hydrates due to depressurizing dissociation of methane and ethane hydrates when the methane and ethane gas pressures were decreased at designated temperatures. The dissociation of methane gas hydrate below below 237 K resulted in the generation of small ice particles on the hydrate surface. A transparent ice sheet formed on the hydrate surface above 242 K. The thickness of the ice sheet on the methane hydrate surface showed the maximum of ca. 30 {mu}m at 253 K. In the case of ethane hydrates, ice particles and ice sheets formed below 262 and 267 respectively. Since the ice particles and ice sheets were formed by water molecules generated during the gas hydrate dissociation, the mechanism of ice sheet formation depends on the dissociation rate of hydrate, ice particle sintering rate, and water molecule

Environmental constraints on West Antarctic ice-sheet formation

Energy Technology Data Exchange (ETDEWEB)

Lindstrom, D R; MacAyeal, D R

1987-01-01

Small perturbations in Antarctic environmental conditions can culminate in the demise of the Antarctic ice sheet's western sector. This may have happened during the last interglacial period, and could recur within the next millennium due to atmospheric warming from trace gas and CO/sub 2/ increases. In this study, we investigate the importance of sea-level, accumulation rate, and ice influx from the East Antarctic ice sheet in the re-establishment of the West Antarctic ice sheet from a thin cover using a time-dependent numerical ice-shelf model. Our results show that a precursor to the West Antarctic ice sheet can form within 3000 years. Sea-level lowering caused by ice-sheet development in the Northern Hemisphere has the greatest environmental influence. Under favorable conditions, ice grounding occurs over all parts of the West Antarctic ice sheet except up-stream of Thwaites Glacier and in the Ross Sea region.

Surface Assisted Formation of methane Hydrates on Ice and Na Montmorillonite Clay

Energy Technology Data Exchange (ETDEWEB)

Gordon, Margaret Ellen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Teich-McGoldrick, Stephanie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Cygan, Randall Timothy [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Meserole, Stephen P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Rodriguez, Mark A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2015-07-01

Methane hydrates are extremely important naturally-occurring crystalline materials that impact climate change, energy resources, geological hazards, and other major environmental issues. Whereas significant experimental effort has been completed to understanding the bulk thermodynamics of methane hydrate assemblies, little is understood on heterogeneous nucleation and growth of methane hydrates in clay-rich environments. Controlled synthesis experiments were completed at 265-285 K and 6.89 MPa to examine the impact of montmorillonite surfaces in clay-ice mixtures to nucleate and form methane hydrate. The results suggest that the hydrophilic and methane adsorbing properties of Namontmorillonite reduce the nucleation period of methane hydrate formation in pure ice systems.

Sea ice - Multiyear cycles and white ice

Science.gov (United States)

Ledley, T. S.

1985-01-01

The multiyear thickness cycles represent one of the interesting features of the sea ice studies performed by Semtner (1976) and Washington et al. (1976) with simple thermodynamic models of sea ice. In the present article, a description is given of results which show that the insulating effect of snow on the surface of the sea ice is important in producing these multiyear cycles given the physics included in the model. However, when the formation of white ice is included, the cycles almost disappear. White ice is the ice which forms at the snow-ice interface when the snow layer becomes thick enough to depress the ice below the water level. Water infiltrates the snow by coming through the ice at leads and generally freezes there, forming white ice.

Repair pathways independent of the Fanconi anemia nuclear core complex play a predominant role in mitigating formaldehyde-induced DNA damage

International Nuclear Information System (INIS)

Noda, Taichi; Takahashi, Akihisa; Kondo, Natsuko; Mori, Eiichiro; Okamoto, Noritomo; Nakagawa, Yosuke; Ohnishi, Ken; Zdzienicka, Malgorzata Z.; Thompson, Larry H.; Helleday, Thomas; Asada, Hideo

2011-01-01

The role of the Fanconi anemia (FA) repair pathway for DNA damage induced by formaldehyde was examined in the work described here. The following cell types were used: mouse embryonic fibroblast cell lines FANCA -/- , FANCC -/- , FANCA -/- C -/- , FANCD2 -/- and their parental cells, the Chinese hamster cell lines FANCD1 mutant (mt), FANCGmt, their revertant cells, and the corresponding wild-type (wt) cells. Cell survival rates were determined with colony formation assays after formaldehyde treatment. DNA double strand breaks (DSBs) were detected with an immunocytochemical γH2AX-staining assay. Although the sensitivity of FANCA -/- , FANCC -/- and FANCA -/- C -/- cells to formaldehyde was comparable to that of proficient cells, FANCD1mt, FANCGmt and FANCD2 -/- cells were more sensitive to formaldehyde than the corresponding proficient cells. It was found that homologous recombination (HR) repair was induced by formaldehyde. In addition, γH2AX foci in FANCD1mt cells persisted for longer times than in FANCD1wt cells. These findings suggest that formaldehyde-induced DSBs are repaired by HR through the FA repair pathway which is independent of the FA nuclear core complex. -- Research highlights: → We examined to clarify the repair pathways of formaldehyde-induced DNA damage. Formaldehyde induces DNA double strand breaks (DSBs). → DSBs are repaired through the Fanconi anemia (FA) repair pathway. → This pathway is independent of the FA nuclear core complex. → We also found that homologous recombination repair was induced by formaldehyde.

The role of sediment supply in esker formation and ice tunnel evolution

Science.gov (United States)

Burke, Matthew J.; Brennand, Tracy A.; Sjogren, Darren B.

2015-05-01

Meltwater is an important part of the glacier system as it can directly influence ice sheet dynamics. Although it is important that ice sheet models incorporate accurate information about subglacial meltwater processes, the relative inaccessibility of contemporary ice sheet beds makes direct investigation challenging. Former ice sheet beds contain a wealth of meltwater landforms such as eskers that, if accurately interpreted, can provide detailed insight into the hydrology of former ice sheets. Eskers are the casts of ice-walled channels and are a common landform within the footprint of the last Laurentide and Cordilleran Ice Sheets. In south-western Alberta, esker distribution suggests that both water and sediment supply may have been important controls; the longest esker ridge segments are located within meltwater valleys partially filled by glaciofluvial sediments, whereas the shortest esker ridge segments are located in areas dominated by clast-poor till. Through detailed esker ridge planform and crest-type mapping, and near surface geophysics we reveal morpho-sedimentary relationships that suggest esker sedimentation was dynamic, but that esker distribution and architecture were primarily governed by sediment supply. Through comparison of these data with data from eskers elsewhere, we suggest three formative scenarios: 1) where sediment supply and flow powers were high, coarse sediment loads result in rapid deposition, and rates of thermo-mechanical ice tunnel growth is exceeded by the rate of ice tunnel closure due to sediment infilling. High sedimentation rates reduce ice tunnel cross-sectional area, cause an increase in meltwater flow velocity and force ice tunnel growth. Thus, ice tunnel growth is fastest where sedimentation rate is highest; this positive feedback results in a non-uniform ice tunnel geometry, and favours macroform development and non-uniform ridge geometry. 2) Where sediment supply is limited, but flow power high, the rate of sedimentation

Photochemical decomposition of Formaldehyde in solution

International Nuclear Information System (INIS)

Garrido Z, G.

1995-01-01

In this work was studied the effect of ultraviolet radiation produced by a mercury low pressure lamp in solutions of formaldehyde. These solutions were exposed to ultraviolet rays at different times. In some of these series of solutions was added a photosensibilizer in order to obtain a high photodecomposition of formaldehyde. The techniques used for determine the products of the decomposition were the following: 1. In order to measure the residual formaldehyde and glioxal, the Hantzsch and 2,4-dinitrophenylhydrazine methods were used. 2. pH's measurements of the solutions, before and after exposition. 3. Paper's chromatography for determine presence of formed acids. 4. Acid-base tritiations for measure total acidification. We observed that when the time of exposition to UV rays was increased, a high photodecomposition of formaldehyde was formed and, besides, a greater quantity of another products. Of the reagents used like photosensibilizers, with the ruthenium reagent, the best results were obtained. (Author)

Recent rift formation and impact on the structural integrity of the Brunt Ice Shelf, East Antarctica

Science.gov (United States)

De Rydt, Jan; Hilmar Gudmundsson, G.; Nagler, Thomas; Wuite, Jan; King, Edward C.

2018-02-01

We report on the recent reactivation of a large rift in the Brunt Ice Shelf, East Antarctica, in December 2012 and the formation of a 50 km long new rift in October 2016. Observations from a suite of ground-based and remote sensing instruments between January 2000 and July 2017 were used to track progress of both rifts in unprecedented detail. Results reveal a steady accelerating trend in their width, in combination with alternating episodes of fast ( > 600 m day-1) and slow propagation of the rift tip, controlled by the heterogeneous structure of the ice shelf. A numerical ice flow model and a simple propagation algorithm based on the stress distribution in the ice shelf were successfully used to hindcast the observed trajectories and to simulate future rift progression under different assumptions. Results show a high likelihood of ice loss at the McDonald Ice Rumples, the only pinning point of the ice shelf. The nascent iceberg calving and associated reduction in pinning of the Brunt Ice Shelf may provide a uniquely monitored natural experiment of ice shelf variability and provoke a deeper understanding of similar processes elsewhere in Antarctica.

Subglacial hydrology and the formation of ice streams.

Science.gov (United States)

Kyrke-Smith, T M; Katz, R F; Fowler, A C

2014-01-08

Antarctic ice streams are associated with pressurized subglacial meltwater but the role this water plays in the dynamics of the streams is not known. To address this, we present a model of subglacial water flow below ice sheets, and particularly below ice streams. The base-level flow is fed by subglacial melting and is presumed to take the form of a rough-bedded film, in which the ice is supported by larger clasts, but there is a millimetric water film which submerges the smaller particles. A model for the film is given by two coupled partial differential equations, representing mass conservation of water and ice closure. We assume that there is no sediment transport and solve for water film depth and effective pressure. This is coupled to a vertically integrated, higher order model for ice-sheet dynamics. If there is a sufficiently small amount of meltwater produced (e.g. if ice flux is low), the distributed film and ice sheet are stable, whereas for larger amounts of melt the ice-water system can become unstable, and ice streams form spontaneously as a consequence. We show that this can be explained in terms of a multi-valued sliding law, which arises from a simplified, one-dimensional analysis of the coupled model.

CO2-based hydrogen storage - Hydrogen generation from formaldehyde/water

Science.gov (United States)

Trincado, Monica; Grützmacher, Hansjörg; Prechtl, Martin H. G.

2018-04-01

Formaldehyde (CH2O) is the simplest and most significant industrially produced aldehyde. The global demand is about 30 megatons annually. Industrially it is produced by oxidation of methanol under energy intensive conditions. More recently, new fields of application for the use of formaldehyde and its derivatives as, i.e. cross-linker for resins or disinfectant, have been suggested. Dialkoxymethane has been envisioned as a combustion fuel for conventional engines or aqueous formaldehyde and paraformaldehyde may act as a liquid organic hydrogen carrier molecule (LOHC) for hydrogen generation to be used for hydrogen fuel cells. For the realization of these processes, it requires less energy-intensive technologies for the synthesis of formaldehyde. This overview summarizes the recent developments in low-temperature reductive synthesis of formaldehyde and its derivatives and low-temperature formaldehyde reforming. These aspects are important for the future demands on modern societies' energy management, in the form of a methanol and hydrogen economy, and the required formaldehyde feedstock for the manufacture of many formaldehyde-based daily products.

Control and Prevention of Ice Formation on the Surface of an Aluminum Alloy

DEFF Research Database (Denmark)

Rahimi, Maral

modified with (3-aminopropyl) triethoxy silane (APTES) exhibited longer freezing delays as compared to both more hydrophilic and more hydrophobic substrates. This is attributed to a particular surface chemistry of the APTES modification that prevents ice formation at the interface of the substrate due...

COMPUTATIONAL STUDY OF INTERSTELLAR GLYCINE FORMATION OCCURRING AT RADICAL SURFACES OF WATER-ICE DUST PARTICLES

International Nuclear Information System (INIS)

Rimola, Albert; Sodupe, Mariona; Ugliengo, Piero

2012-01-01

Glycine is the simplest amino acid, and due to the significant astrobiological implications that suppose its detection, the search for it in the interstellar medium (ISM), meteorites, and comets is intensively investigated. In the present work, quantum mechanical calculations based on density functional theory have been used to model the glycine formation on water-ice clusters present in the ISM. The removal of either one H atom or one electron from the water-ice cluster has been considered to simulate the effect of photolytic radiation and of ionizing particles, respectively, which lead to the formation of OH . radical and H 3 O + surface defects. The coupling of incoming CO molecules with the surface OH . radicals on the ice clusters yields the formation of the COOH . radicals via ZPE-corrected energy barriers and reaction energies of about 4-5 kcal mol –1 and –22 kcal mol –1 , respectively. The COOH . radicals couple with incoming NH=CH 2 molecules (experimentally detected in the ISM) to form the NHCH 2 COOH . radical glycine through energy barriers of 12 kcal mol –1 , exceedingly high at ISM cryogenic temperatures. Nonetheless, when H 3 O + is present, one proton may be barrierless transferred to NH=CH 2 to give NH 2 =CH 2 + . This latter may react with the COOH . radical to give the NH 2 CH 2 COOH +. glycine radical cation which can then be transformed into the NH 2 CHC(OH) 2 +. species (the most stable form of glycine in its radical cation state) or into the NH 2 CHCOOH . neutral radical glycine. Estimated rate constants of these events suggest that they are kinetically feasible at temperatures of 100-200 K, which indicate that their occurrence may take place in hot molecular cores or in comets exposed to warmer regions of solar systems. Present results provide quantum chemical evidence that defects formed on water ices due to the harsh-physical conditions of the ISM may trigger reactions of cosmochemical interest. The relevance of surface H 3 O

Computational Study of Interstellar Glycine Formation Occurring at Radical Surfaces of Water-ice Dust Particles

Science.gov (United States)

Rimola, Albert; Sodupe, Mariona; Ugliengo, Piero

2012-07-01

Glycine is the simplest amino acid, and due to the significant astrobiological implications that suppose its detection, the search for it in the interstellar medium (ISM), meteorites, and comets is intensively investigated. In the present work, quantum mechanical calculations based on density functional theory have been used to model the glycine formation on water-ice clusters present in the ISM. The removal of either one H atom or one electron from the water-ice cluster has been considered to simulate the effect of photolytic radiation and of ionizing particles, respectively, which lead to the formation of OH• radical and H3O+ surface defects. The coupling of incoming CO molecules with the surface OH• radicals on the ice clusters yields the formation of the COOH• radicals via ZPE-corrected energy barriers and reaction energies of about 4-5 kcal mol-1 and -22 kcal mol-1, respectively. The COOH• radicals couple with incoming NH=CH2 molecules (experimentally detected in the ISM) to form the NHCH2COOH• radical glycine through energy barriers of 12 kcal mol-1, exceedingly high at ISM cryogenic temperatures. Nonetheless, when H3O+ is present, one proton may be barrierless transferred to NH=CH2 to give NH2=CH2 +. This latter may react with the COOH• radical to give the NH2CH2COOH+• glycine radical cation which can then be transformed into the NH2CHC(OH)2 +• species (the most stable form of glycine in its radical cation state) or into the NH2CHCOOH• neutral radical glycine. Estimated rate constants of these events suggest that they are kinetically feasible at temperatures of 100-200 K, which indicate that their occurrence may take place in hot molecular cores or in comets exposed to warmer regions of solar systems. Present results provide quantum chemical evidence that defects formed on water ices due to the harsh-physical conditions of the ISM may trigger reactions of cosmochemical interest. The relevance of surface H3O+ ions to facilitate chemical

Repair pathways independent of the Fanconi anemia nuclear core complex play a predominant role in mitigating formaldehyde-induced DNA damage

Energy Technology Data Exchange (ETDEWEB)

Noda, Taichi [Department of Biology, School of Medicine, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8521 (Japan); Department of Dermatology, School of Medicine, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8521 (Japan); Takahashi, Akihisa [Department of Biology, School of Medicine, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8521 (Japan); Kondo, Natsuko [Particle Radiation Oncology Research Center, Research Reactor Institute, Kyoto University, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan); Mori, Eiichiro [Department of Biology, School of Medicine, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8521 (Japan); Okamoto, Noritomo [Department of Otorhinolaryngology, School of Medicine, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8521 (Japan); Nakagawa, Yosuke [Department of Oral and Maxillofacial Surgery, School of Medicine, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8521 (Japan); Ohnishi, Ken [Department of Biology, Ibaraki Prefectual University of Health Sciences, 4669-2 Ami, Ami-mati, Inasiki-gun, Ibaraki 300-0394 (Japan); Zdzienicka, Malgorzata Z. [Department of Molecular Cell Genetics, Collegium Medicum in Bydgoszcz, Nicolaus-Copernicus-University in Torun, ul. Sklodowskiej-Curie 9, 85-094 Bydgoszcz (Poland); Thompson, Larry H. [Biosciences and Biotechnology Division, L452, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551-0808 (United States); Helleday, Thomas [Gray Institute for Radiation Oncology and Biology, University of Oxford, Old Road Campus Research Building, Off Roosevelt Drive, Oxford, OX3 7DQ (United Kingdom); Department of Genetics, Microbiology and Toxicology Stockholm University, SE-106 91 Stockholm (Sweden); Asada, Hideo [Department of Dermatology, School of Medicine, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8521 (Japan); and others

2011-01-07

The role of the Fanconi anemia (FA) repair pathway for DNA damage induced by formaldehyde was examined in the work described here. The following cell types were used: mouse embryonic fibroblast cell lines FANCA{sup -/-}, FANCC{sup -/-}, FANCA{sup -/-}C{sup -/-}, FANCD2{sup -/-} and their parental cells, the Chinese hamster cell lines FANCD1 mutant (mt), FANCGmt, their revertant cells, and the corresponding wild-type (wt) cells. Cell survival rates were determined with colony formation assays after formaldehyde treatment. DNA double strand breaks (DSBs) were detected with an immunocytochemical {gamma}H2AX-staining assay. Although the sensitivity of FANCA{sup -/-}, FANCC{sup -/-} and FANCA{sup -/-}C{sup -/-} cells to formaldehyde was comparable to that of proficient cells, FANCD1mt, FANCGmt and FANCD2{sup -/-} cells were more sensitive to formaldehyde than the corresponding proficient cells. It was found that homologous recombination (HR) repair was induced by formaldehyde. In addition, {gamma}H2AX foci in FANCD1mt cells persisted for longer times than in FANCD1wt cells. These findings suggest that formaldehyde-induced DSBs are repaired by HR through the FA repair pathway which is independent of the FA nuclear core complex. -- Research highlights: {yields} We examined to clarify the repair pathways of formaldehyde-induced DNA damage. Formaldehyde induces DNA double strand breaks (DSBs). {yields} DSBs are repaired through the Fanconi anemia (FA) repair pathway. {yields} This pathway is independent of the FA nuclear core complex. {yields} We also found that homologous recombination repair was induced by formaldehyde.

The formation of multiple layers of ice particles in the polar summer mesopause region

Directory of Open Access Journals (Sweden)

H. Li

2016-01-01

Full Text Available This paper presents a two-dimensional theoretical model to study the formation process of multiple layers of small ice particles in the polar summer mesosphere as measured by rockets and associated with polar mesosphere summer echoes (PMSE. The proposed mechanism primarily takes into account the transport processes induced by gravity waves through collision coupling between the neutral atmosphere and the ice particles. Numerical solutions of the model indicate that the dynamic influence of wind variation induced by gravity waves can make a significant contribution to the vertical and horizontal transport of ice particles and ultimately transform them into thin multiple layers. Additionally, the pattern of the multiple layers at least partially depends on the vertical wavelength of the gravity wave, the ice particle size and the wind velocity. The results presented in this paper will be helpful to better understand the occurrence of multiple layers of PMSE as well as its variation process.

7746 CONCENTRATIONS OF FORMALDEHYDE IN RAIN WATERS ...

African Journals Online (AJOL)

Win7Ent

2013-06-03

Jun 3, 2013 ... The chromotropic acid method described by the. National Institute for ... concentration range of the formaldehyde in the rain waters varied from month to month throughout the six ... vicinity of vegetation [3]. Formaldehyde is the ...

Formaldehyde as an antiseptic in the production of alcohol from molasses

Energy Technology Data Exchange (ETDEWEB)

Rosa, M; Vernerova, J; Stros, F

1962-01-01

The effect of formaldehyde as an antiseptic for the noncontaminated alcohol fermentation of molasses was examined with five different yeast-mash batches containing formaldehyde 0.01%. Following 24 hour cultivation, increase in the activity of formaldehyde-inoculated mash was lowered by 47%; the formaldehyde decreased the alcohol fermentation and lessened the rate of fermentation of sugar by 20% in noncontaminated mash. The decrease in the fermentation rate was also observed during the entire course of fermentation. On the other hand, formaldehyde addition to molasses contaminated with lactic acid bacteria accelerated the fermentation rate by inhibiting the bacterial growth; the degree of retardation due to the contamination was greater than that due to the antiseptic. The view that formaldehyde decreased the effectiveness of growth substances by binding the amino acid present in mash mixtures could not be confirmed; it was believed that formaldehyde was absorbed by yeast cells even through the entities thus destroyed could not be differentiated from living cells by methylene blue. Higher resistance of yeast cultures to formaldehyde was obtained by repeated transfers of the yeast in media containing formaldehyde. It was concluded that formaldehyde added to contaminated molasses inhibited the further growth of the contamination, increased yield of ethanol on the basis of the sugar, and simultaneously decreased the net yield of ethanol in contrast to the yield from noncontaminated mashes in the absence of formaldehyde.

Ice cloud formation potential by free tropospheric particles from long-range transport over the Northern Atlantic Ocean

Science.gov (United States)

China, Swarup; Alpert, Peter A.; Zhang, Bo; Schum, Simeon; Dzepina, Katja; Wright, Kendra; Owen, R. Chris; Fialho, Paulo; Mazzoleni, Lynn R.; Mazzoleni, Claudio; Knopf, Daniel A.

2017-03-01

Long-range transported free tropospheric particles can play a significant role on heterogeneous ice nucleation. Using optical and electron microscopy we examine the physicochemical characteristics of ice nucleating particles (INPs). Particles were collected on substrates from the free troposphere at the remote Pico Mountain Observatory in the Azores Islands, after long-range transport and aging over the Atlantic Ocean. We investigate four specific events to study the ice formation potential by the collected particles with different ages and transport patterns. We use single-particle analysis, as well as bulk analysis to characterize particle populations. Both analyses show substantial differences in particle composition between samples from the four events; in addition, single-particle microscopy analysis indicates that most particles are coated by organic material. The identified INPs contained mixtures of dust, aged sea salt and soot, and organic material acquired either at the source or during transport. The temperature and relative humidity (RH) at which ice formed, varied only by 5% between samples, despite differences in particle composition, sources, and transport patterns. We hypothesize that this small variation in the onset RH may be due to the coating material on the particles. This study underscores and motivates the need to further investigate how long-range transported and atmospherically aged free tropospheric particles impact ice cloud formation.

Recent rift formation and impact on the structural integrity of the Brunt Ice Shelf, East Antarctica

Directory of Open Access Journals (Sweden)

J. De Rydt

2018-02-01

Full Text Available We report on the recent reactivation of a large rift in the Brunt Ice Shelf, East Antarctica, in December 2012 and the formation of a 50 km long new rift in October 2016. Observations from a suite of ground-based and remote sensing instruments between January 2000 and July 2017 were used to track progress of both rifts in unprecedented detail. Results reveal a steady accelerating trend in their width, in combination with alternating episodes of fast ( > 600 m day−1 and slow propagation of the rift tip, controlled by the heterogeneous structure of the ice shelf. A numerical ice flow model and a simple propagation algorithm based on the stress distribution in the ice shelf were successfully used to hindcast the observed trajectories and to simulate future rift progression under different assumptions. Results show a high likelihood of ice loss at the McDonald Ice Rumples, the only pinning point of the ice shelf. The nascent iceberg calving and associated reduction in pinning of the Brunt Ice Shelf may provide a uniquely monitored natural experiment of ice shelf variability and provoke a deeper understanding of similar processes elsewhere in Antarctica.

Dead-ice environments

DEFF Research Database (Denmark)

Krüger, Johannes; Kjær, Kurt H.; Schomacker, Anders

2010-01-01

glacier environment. The scientific challenges are to answer the key questions. What are the conditions for dead-ice formation? From which sources does the sediment cover originate? Which melting and reworking processes act in the ice-cored moraines? What is the rate of de-icing in the ice-cored moraines...

Bacterial community dynamics and activity in relation to dissolved organic matter availability during sea-ice formation in a mesocosm experiment.

Science.gov (United States)

Eronen-Rasimus, Eeva; Kaartokallio, Hermanni; Lyra, Christina; Autio, Riitta; Kuosa, Harri; Dieckmann, Gerhard S; Thomas, David N

2014-02-01

The structure of sea-ice bacterial communities is frequently different from that in seawater. Bacterial entrainment in sea ice has been studied with traditional microbiological, bacterial abundance, and bacterial production methods. However, the dynamics of the changes in bacterial communities during the transition from open water to frozen sea ice is largely unknown. Given previous evidence that the nutritional status of the parent water may affect bacterial communities during ice formation, bacterial succession was studied in under ice water and sea ice in two series of mesocosms: the first containing seawater from the North Sea and the second containing seawater enriched with algal-derived dissolved organic matter (DOM). The composition and dynamics of bacterial communities were investigated with terminal restriction fragment length polymorphism (T-RFLP), and cloning alongside bacterial production (thymidine and leucine uptake) and abundance measurements (measured by flow cytometry). Enriched and active sea-ice bacterial communities developed in ice formed in both unenriched and DOM-enriched seawater (0-6 days). γ-Proteobacteria dominated in the DOM-enriched samples, indicative of their capability for opportunistic growth in sea ice. The bacterial communities in the unenriched waters and ice consisted of the classes Flavobacteria, α- and γ-Proteobacteria, which are frequently found in natural sea ice in polar regions. Furthermore, the results indicate that seawater bacterial communities are able to adapt rapidly to sudden environmental changes when facing considerable physicochemical stress such as the changes in temperature, salinity, nutrient status, and organic matter supply during ice formation. © 2014 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

Bioinspired Materials for Controlling Ice Nucleation, Growth, and Recrystallization.

Science.gov (United States)

He, Zhiyuan; Liu, Kai; Wang, Jianjun

2018-05-15

Ice formation, mainly consisting of ice nucleation, ice growth, and ice recrystallization, is ubiquitous and crucial in wide-ranging fields from cryobiology to atmospheric physics. Despite active research for more than a century, the mechanism of ice formation is still far from satisfactory. Meanwhile, nature has unique ways of controlling ice formation and can provide resourceful avenues to unravel the mechanism of ice formation. For instance, antifreeze proteins (AFPs) protect living organisms from freezing damage via controlling ice formation, for example, tuning ice nucleation, shaping ice crystals, and inhibiting ice growth and recrystallization. In addition, AFP mimics can have applications in cryopreservation of cells, tissues, and organs, food storage, and anti-icing materials. Therefore, continuous efforts have been made to understand the mechanism of AFPs and design AFP inspired materials. In this Account, we first review our recent research progress in understanding the mechanism of AFPs in controlling ice formation. A Janus effect of AFPs on ice nucleation was discovered, which was achieved via selectively tethering the ice-binding face (IBF) or the non-ice-binding face (NIBF) of AFPs to solid surfaces and investigating specifically the effect of the other face on ice nucleation. Through molecular dynamics (MD) simulation analysis, we observed ordered hexagonal ice-like water structure atop the IBF and disordered water structure atop the NIBF. Therefore, we conclude that the interfacial water plays a critical role in controlling ice formation. Next, we discuss the design and fabrication of AFP mimics with capabilities in tuning ice nucleation and controlling ice shape and growth, as well as inhibiting ice recrystallization. For example, we tuned ice nucleation via modifying solid surfaces with supercharged unfolded polypeptides (SUPs) and polyelectrolyte brushes (PBs) with different counterions. We found graphene oxide (GO) and oxidized quasi

Ice condensation on sulfuric acid tetrahydrate: Implications for polar stratospheric ice clouds

Directory of Open Access Journals (Sweden)

T. J. Fortin

2003-01-01

Full Text Available The mechanism of ice nucleation to form Type 2 PSCs is important for controlling the ice particle size and hence the possible dehydration in the polar winter stratosphere. This paper probes heterogeneous ice nucleation on sulfuric acid tetrahydrate (SAT. Laboratory experiments were performed using a thin-film, high-vacuum apparatus in which the condensed phase is monitored via Fourier transform infrared spectroscopy and water pressure is monitored with the combination of an MKS baratron and an ionization gauge. Results show that SAT is an efficient ice nucleus with a critical ice saturation ratio of S*ice = 1.3 to 1.02 over the temperature range 169.8-194.5 K. This corresponds to a necessary supercooling of 0.1-1.3 K below the ice frost point. The laboratory data is used as input for a microphysical/photochemical model to probe the effect that this heterogeneous nucleation mechanism could have on Type 2 PSC formation and stratospheric dehydration. In the model simulations, even a very small number of SAT particles (e.g., 10-3 cm-3 result in ice nucleation on SAT as the dominant mechanism for Type 2 PSC formation. As a result, Type 2 PSC formation is more widespread, leading to larger-scale dehydration. The characteristics of the clouds are controlled by the assumed number of SAT particles present, demonstrating that a proper treatment of SAT is critical for correctly modeling Type 2 PSC formation and stratospheric dehydration.

Ice cream structure modification by ice-binding proteins.

Science.gov (United States)

Kaleda, Aleksei; Tsanev, Robert; Klesment, Tiina; Vilu, Raivo; Laos, Katrin

2018-04-25

Ice-binding proteins (IBPs), also known as antifreeze proteins, were added to ice cream to investigate their effect on structure and texture. Ice recrystallization inhibition was assessed in the ice cream mixes using a novel accelerated microscope assay and the ice cream microstructure was studied using an ice crystal dispersion method. It was found that adding recombinantly produced fish type III IBPs at a concentration 3 mg·L -1 made ice cream hard and crystalline with improved shape preservation during melting. Ice creams made with IBPs (both from winter rye, and type III IBP) had aggregates of ice crystals that entrapped pockets of the ice cream mixture in a rigid network. Larger individual ice crystals and no entrapment in control ice creams was observed. Based on these results a model of ice crystals aggregates formation in the presence of IBPs was proposed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Contrasts in Sea Ice Formation and Production in the Arctic Seasonal and Perennial Ice Zones

Science.gov (United States)

Kwok, R.

2006-01-01

Four years (1997-2000) of RADARSAT Geophysical Processor System (RGPS) data are used to contrast the sea ice deformation and production regionally, and in the seasonal (SIZ) and perennial (PIZ) ice zones. Ice production is of seasonal ice in openings during the winter. 3-day estimates of these quantities are provided within Lagrangian elements initially 10 km on a side. A distinct seasonal cycle is seen in both zones with these estimates highest in the late fall and with seasonal minimums in the mid-winter. Regional divergence over the winter could be up to 30%. Spatially, the highest deformation is in the SIZ north of coastal Alaska. Both ice deformation and production are higher in the SIZ: deformation-related ice production in the SIZ (approx.0.5 m) is 1.5-2.3 times that of the PIZ (approx.0.3 m) - this is connected to ice strength and thickness. Atmospheric forcing and boundary layer structure contribute to only the seasonal and interannual variability. Seasonal ice growth in ice fractures accounts for approx.25-40% of the total ice production of the Arctic Ocean. By itself, this deformation-ice production relationship could be considered a negative feedback when thickness is perturbed. However, the overall effect on ice production in the face of increasing seasonal and thinner/weaker ice coverage could be modified by: local destabilization of the water column promoting overturning of warmer water due to increased brine rejection; and, the upwelling of the pynocline associated with increased occurrence of large shear motion in sea ice.

Development of melamine modified urea formaldehyde resins based o nstrong acidic pH catalyzed urea formaldehyde polymer

Science.gov (United States)

Chung-Yun Hse

2009-01-01

To upgrade the performance of urea-formaldehyde (UF) resin bonded particleboards, melamine modified urea-formaldehyde (MUF) resins based on strong acidic pH catalyzed UF polymers were investigated. The study was conducted in a series of two experiments: 1) formulation of MUF resins based on a UF polymer catalyzed with strong acidic pH and 2) determination of the...

ELECTRON IRRADIATION OF KUIPER BELT SURFACE ICES: TERNARY N2-CH4-CO MIXTURES AS A CASE STUDY

International Nuclear Information System (INIS)

Kim, Y. S.; Kaiser, R. I.

2012-01-01

The space weathering of icy Kuiper Belt Objects was investigated in this case study by exposing methane (CH 4 ) and carbon monoxide (CO) doped nitrogen (N 2 ) ices at 10 K to ionizing radiation in the form of energetic electrons. Online and in situ Fourier transform infrared spectroscopy was utilized to monitor the radiation-induced chemical processing of these ices. Along with isocyanic acid (HNCO), the products could be mainly derived from those formed in irradiated binary ices of the N 2 -CH 4 and CO-CH 4 systems: nitrogen-bearing products were found in the form of hydrogen cyanide (HCN), hydrogen isocyanide (HNC), diazomethane (CH 2 N 2 ), and its radical fragment (HCN 2 ); oxygen-bearing products were of acetaldehyde (CH 3 CHO), formyl radical (HCO), and formaldehyde (H 2 CO). As in the pure ices, the methyl radical (CH 3 ) and ethane (C 2 H 6 ) were also detected, as were carbon dioxide (CO 2 ) and the azide radical (N 3 ). Based on the temporal evolution of the newly formed products, kinetic reaction schemes were then developed to fit the temporal profiles of the newly formed species, resulting in numerical sets of rate constants. The current study highlights important constraints on the preferential formation of isocyanic acid (HNCO) over hydrogen cyanide (HCN) and hydrogen isocyanide (HNC), thus guiding the astrobiological and chemical evolution of those distant bodies.

A fate for organic acids, formaldehyde and methanol in cloud water: their biotransformation by micro-organisms

Directory of Open Access Journals (Sweden)

P. Amato

2007-08-01

Full Text Available The interactions between microbial and chemical contents of cloud water were investigated. First, we observe that the bulk cloud water solution provides a substantial environment where bacteria can develop significantly. Then, a total number of 60 microbial strains originating from seven distinct samples of cloud water and affiliated to various taxonomic groups were examined for their ability to degrade some of the main atmospheric carboxylic compounds: formate, acetate, lactate, succinate, as well as formaldehyde and methanol. Biodegradation tests show that all these compounds can be transformed when used as single carbonaceous substrates, with activities depending on both the strain and the compound. The highest capacities of biodegradation are observed towards formaldehyde, formate and acetate, which are also the more concentrated compounds typically measured in cloud water. Hence, analyses by ¹H NMR permitted to establish for instance that compounds like pyruvate or fumarate can be produced and released in the media in relation to the transformation of lactate or succinate. In addition, utilization of ¹³C labelled formaldehyde showed that it can be transformed through many metabolic pathways, similar to those induced by photochemistry and leading to the production of formate and/or methanol. These results suggest that microorganisms of cloud water can have various behaviours towards the chemical compounds present in the atmosphere: they can represent either a sink or source for organic carbon, and may have to be considered as actors of cloud chemistry.

the histological effects of formaldehyde vapour on the lungs

African Journals Online (AJOL)

Uwaifoh

2012-12-31

Dec 31, 2012 ... In the world day, the active chemical used for embalming is formaldehyde. ... formaldehyde causes nasopharyngeal cancer in humans,” (Collins et al., 1997; Gardner et ... pattern for inhalation of formaldehyde in rats presented cell ... temperature of about 25-28oC and photo-periodicity of 12h day/ 12h night.

National Ice Center Arctic Sea Ice Charts and Climatologies in Gridded Format

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The U.S. National Ice Center (NIC) is an inter-agency sea ice analysis and forecasting center comprised of the Department of Commerce/NOAA, the Department of...

Development of a formaldehyde biosensor with application to synthetic methylotrophy.

Science.gov (United States)

Woolston, Benjamin M; Roth, Timothy; Kohale, Ishwar; Liu, David R; Stephanopoulos, Gregory

2018-01-01

Formaldehyde is a prevalent environmental toxin and a key intermediate in single carbon metabolism. The ability to monitor formaldehyde concentration is, therefore, of interest for both environmental monitoring and for metabolic engineering of native and synthetic methylotrophs, but current methods suffer from low sensitivity, complex workflows, or require expensive analytical equipment. Here we develop a formaldehyde biosensor based on the FrmR repressor protein and cognate promoter of Escherichia coli. Optimization of the native repressor binding site and regulatory architecture enabled detection at levels as low as 1 µM. We then used the sensor to benchmark the in vivo activity of several NAD-dependent methanol dehydrogenase (Mdh) variants, the rate-limiting enzyme that catalyzes the first step of methanol assimilation. In order to use this biosensor to distinguish individuals in a mixed population of Mdh variants, we developed a strategy to prevent cross-talk by using glutathione as a formaldehyde sink to minimize intercellular formaldehyde diffusion. Finally, we applied this biosensor to balance expression of mdh and the formaldehyde assimilation enzymes hps and phi in an engineered E. coli strain to minimize formaldehyde build-up while also reducing the burden of heterologous expression. This biosensor offers a quick and simple method for sensitively detecting formaldehyde, and has the potential to be used as the basis for directed evolution of Mdh and dynamic formaldehyde control strategies for establishing synthetic methylotrophy. © 2017 Wiley Periodicals, Inc.

Status of iodine in formaldehyde-preserved milk - revisited

International Nuclear Information System (INIS)

Montgomery, D.M.; Gibson, J.E.

1977-01-01

The results of an investigation into the effect of formaldehyde preservation of raw milk in view of the differences observed by Murthy (J. Dairy Sci.; 45:1066 (1962) and J. Dairy Sci.; 49:1190 (1966)) and Thomas (personal communication. (1976)) are reported. The use of the specific electrode method for iodine analysis of formaldehyde-preserved milk has also been investigated. It was found that the Thomas preservation technique for 4 litre milk samples for 131 I analysis was acceptable, and an aliquot of the formaldehyde-preserved milk can be analyzed for total iodide concentration by the electrode method. Milk samples may also be preserved for stable iodide measurement (without iodide carrier addition) by addition of formaldehyde at 0.5 M concentration. (U.K.)

Formation of large (≃100 μm ice crystals near the tropical tropopause

Directory of Open Access Journals (Sweden)

M. J. Alexander

2008-03-01

Full Text Available Recent high-altitude aircraft measurements with in situ imaging instruments indicated the presence of relatively large (≃100 μm length, thin (aspect ratios of ≃6:1 or larger hexagonal plate ice crystals near the tropical tropopause in very low concentrations (<0.01 L−1. These crystals were not produced by deep convection or aggregation. We use simple growth-sedimentation calculations as well as detailed cloud simulations to evaluate the conditions required to grow the large crystals. Uncertainties in crystal aspect ratio leave a range of possibilities, which could be constrained by knowledge of the water vapor concentration in the air where the crystal growth occurred. Unfortunately, water vapor measurements made in the cloud formation region near the tropopause with different instruments ranged from <2 ppmv to ≃3.5 ppmv. The higher water vapor concentrations correspond to very large ice supersaturations (relative humidities with respect to ice of about 200%. If the aspect ratios of the hexagonal plate crystals are as small as the image analysis suggests (6:1, see companion paper (Lawson et al., 2008 then growth of the large crystals before they sediment out of the supersaturated layer would only be possible if the water vapor concentration were on the high end of the range indicated by the different measurements (>3 ppmv. On the other hand, if the crystal aspect ratios are quite a bit larger (≃10:1, then H2O concentrations toward the low end of the measurement range (≃2–2.5 ppmv would suffice to grow the large crystals. Gravity-wave driven temperature and vertical wind perturbations only slightly modify the H2O concentrations needed to grow the crystals. We find that it would not be possible to grow the large crystals with water concentrations less than 2 ppmv, even with assumptions of a very high aspect ratio of 15 and steady upward motion of 2 cm s−1 to loft the crystals in the tropopause region. These calculations would seem

[Microbial resistance to formaldehyde. I. Comparative quantitative studies in some selected species of vegetative bacteria, bacterial spores, fungi, bacteriophages and viruses].

Science.gov (United States)

Spicher, G; Peters, J

1976-12-01

formaldehyde not higher than those needed for the killing of vegetative gram-negative bacteria were necessary. The conidia of Aspergillus niger were found to be more resistant than the cells of Candida albicans but did not require any higher concentrations than for the killing of Staphylococcus aureus (see Fig. 1 B). In the case of bacterial spores, a special phenomenon was observed. If the spores had been exposed to a temperature of 80 and 95 degrees C, respectively (depending on the species involved) for one or two hours following exposure to formaldehyde, a considerably higher number of spores was found to be capable of germination and colony formation than without such treatment (heat activation: cf. Fig. 2A and Fig. 2B). The spores of Bacillus cereus had only a relatively low resistance to formaldehyde. To reduce the proportion of the spores capable of colony formation to 1/10000, a 2.9% formaldehyde concentration was necessary without heat activation and one of 10.8% with heat activation...

COMPUTATIONAL STUDY OF INTERSTELLAR GLYCINE FORMATION OCCURRING AT RADICAL SURFACES OF WATER-ICE DUST PARTICLES

Energy Technology Data Exchange (ETDEWEB)

Rimola, Albert; Sodupe, Mariona [Departament de Quimica, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain); Ugliengo, Piero, E-mail: albert.rimola@uab.cat [Dipartimento di Chimica, NIS Centre of Excellence and INSTM (Materials and Technology National Consortium), UdR Torino, Universita di Torino, Via P. Giuria 7, 10125 Torino (Italy)

2012-07-20

Glycine is the simplest amino acid, and due to the significant astrobiological implications that suppose its detection, the search for it in the interstellar medium (ISM), meteorites, and comets is intensively investigated. In the present work, quantum mechanical calculations based on density functional theory have been used to model the glycine formation on water-ice clusters present in the ISM. The removal of either one H atom or one electron from the water-ice cluster has been considered to simulate the effect of photolytic radiation and of ionizing particles, respectively, which lead to the formation of OH{sup .} radical and H{sub 3}O{sup +} surface defects. The coupling of incoming CO molecules with the surface OH{sup .} radicals on the ice clusters yields the formation of the COOH{sup .} radicals via ZPE-corrected energy barriers and reaction energies of about 4-5 kcal mol{sup -1} and -22 kcal mol{sup -1}, respectively. The COOH{sup .} radicals couple with incoming NH=CH{sub 2} molecules (experimentally detected in the ISM) to form the NHCH{sub 2}COOH{sup .} radical glycine through energy barriers of 12 kcal mol{sup -1}, exceedingly high at ISM cryogenic temperatures. Nonetheless, when H{sub 3}O{sup +} is present, one proton may be barrierless transferred to NH=CH{sub 2} to give NH{sub 2}=CH{sub 2}{sup +}. This latter may react with the COOH{sup .} radical to give the NH{sub 2}CH{sub 2}COOH{sup +.} glycine radical cation which can then be transformed into the NH{sub 2}CHC(OH){sub 2}{sup +.} species (the most stable form of glycine in its radical cation state) or into the NH{sub 2}CHCOOH{sup .} neutral radical glycine. Estimated rate constants of these events suggest that they are kinetically feasible at temperatures of 100-200 K, which indicate that their occurrence may take place in hot molecular cores or in comets exposed to warmer regions of solar systems. Present results provide quantum chemical evidence that defects formed on water ices due to the harsh

78 FR 34820 - Formaldehyde Emissions Standards for Composite Wood Products

Science.gov (United States)

2013-06-10

.... Examples of sources of formaldehyde gas inside homes include cigarette smoke, unvented, fuel- burning... derived an inhalation unit risk factor for assessing formaldehyde cancer risk. The risk factor and... formaldehyde by inhalation (Ref. 8). This draft IRIS assessment was peer-reviewed by the National Research...

40 CFR 721.3810 - Formaldehyde, polymers with substituted phenols (generic).

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Formaldehyde, polymers with... New Uses for Specific Chemical Substances § 721.3810 Formaldehyde, polymers with substituted phenols... identified generically as Formaldehyde, polymers with substituted phenols (PMN P-99-0558) is subject to...

Formaldehyde as an antiseptic in the production of alcohol from molasses

Energy Technology Data Exchange (ETDEWEB)

Rosa, V J; Stros, F

1962-01-01

The effect of formaldehyde as an antiseptic for the noncontaminated alcohol fermentation of molasses was examined with five different yeasts mash batches containing formaldehyde 0.01%. Following 24 hour cultivation, increase in the activity of formaldehyde-inoculated mash was lowered by 47%; the formaldehyde decreased the alcohol fermentation and lessened the rate of fermentation of sugar by 20% in noncontaminated mash. The decrease in the fermentation rate was also observed during the entire course of fermentation. On the other hand, formaldehyde addition to molasses contaminated with lactic acid bacteria accelerated the fermentation rate.

Rain-on-snow and ice layer formation detection using passive microwave radiometry: An arctic perspective

Science.gov (United States)

Langlois, A.; Royer, A.; Montpetit, B.; Johnson, C. A.; Brucker, L.; Dolant, C.; Richards, A.; Roy, A.

2015-12-01

With the current changes observed in the Arctic, an increase in occurrence of rain-on-snow (ROS) events has been reported in the Arctic (land) over the past few decades. Several studies have established that strong linkages between surface temperatures and passive microwaves do exist, but the contribution of snow properties under winter extreme events such as rain-on-snow events (ROS) and associated ice layer formation need to be better understood that both have a significant impact on ecosystem processes. In particular, ice layer formation is known to affect the survival of ungulates by blocking their access to food. Given the current pronounced warming in northern regions, more frequent ROS can be expected. However, one of the main challenges in the study of ROS in northern regions is the lack of meteorological information and in-situ measurements. The retrieval of ROS occurrence in the Arctic using satellite remote sensing tools thus represents the most viable approach. Here, we present here results from 1) ROS occurrence formation in the Peary caribou habitat using an empirically developed ROS algorithm by our group based on the gradient ratio, 2) ice layer formation across the same area using a semi-empirical detection approach based on the polarization ratio spanning between 1978 and 2013. A detection threshold was adjusted given the platform used (SMMR, SSM/I and AMSR-E), and initial results suggest high-occurrence years as: 1981-1982, 1992-1993; 1994-1995; 1999-2000; 2001-2002; 2002-2003; 2003-2004; 2006-2007; 2007-2008. A trend in occurrence for Banks Island and NW Victoria Island and linkages to caribou population is presented.

Effect of the polymerization with formaldehyde on the thermal reactivity of a low-temperature coal tar pitch

Energy Technology Data Exchange (ETDEWEB)

Jose L. Crespo; Ana Arenillas; Jose A. Vin; Roberto Garcia; Colin E. Snape; Sabino R. Moinelo [Instituto Nacional del Carbon (CSIC), Oviedo (Spain)

2005-04-01

The influence of polymerization with formaldehyde on the thermal reactivity of a low-temperature coal tar pitch has been investigated. The mechanism and extent of the polymerization depends on the catalyst used, the greatest extent of polymerization being achieved under basic catalytic conditions. After the polymerization treatment, samples were carbonized at 420{sup o}C and the products were characterized by optical microscopy. According to the results, polymerization with formaldehyde increases the reactivity of the pitch, giving rise to increased carbonization yields and leading to the formation of the mesophase with milder conditions. The polymerization process also affects the morphology of the resultant anisotropic material, giving rise to the formation of irregularly shaped mesophase particles and reducing the optical texture size of the anisotropic domains, giving mosaic texture, especially when basic catalysis is used. 36 refs., 11 figs., 5 tabs.

Preparation of carbon dioxide adsorbents from the chemical activation of urea-formaldehyde and melamine-formaldehyde resins

Energy Technology Data Exchange (ETDEWEB)

T.C. Drage; A. Arenillas; K.M. Smith; C. Pevida; S. Piippo; C.E. Snape [University of Nottingham, Nottingham (United Kingdom). Nottingham Fuel and Energy Centre, School of Chemical, Environmental and Mining Engineering

2007-01-15

Adsorption is considered to be one of the more promising technologies for the capture of CO{sub 2} from flue gases. In general, nitrogen enrichment is reported to be effective in enhancing the specific adsorbent-adsorbate interaction for CO{sub 2}. Nitrogen enriched carbons were produced from urea-formaldehyde and melamine-formaldehyde resins polymerised in the presence of K{sub 2}CO{sub 3} as a chemical activation agent, with activation undertaken over a range of temperatures. CO{sub 2} adsorption capacity was determined to be dependent upon both textural properties and more importantly nitrogen functionality. Adsorbents capable of capturing above 8 wt.% CO{sub 2} at 25{sup o}C were produced from the chemical activation of urea-formaldehyde resin at 500{sup o}C. Chemical activation seems to produce more effective adsorbents than CO{sub 2} activation. 29 refs., 4 figs., 3 tabs.

THE EFFECTS OF GRAIN SIZE AND TEMPERATURE DISTRIBUTIONS ON THE FORMATION OF INTERSTELLAR ICE MANTLES

Energy Technology Data Exchange (ETDEWEB)

Pauly, Tyler; Garrod, Robin T., E-mail: tap74@cornell.edu [Cornell Center for Astrophysics and Planetary Science, Cornell University, Ithaca, NY 14853-6801 (United States)

2016-02-01

Computational models of interstellar gas-grain chemistry have historically adopted a single dust-grain size of 0.1 micron, assumed to be representative of the size distribution present in the interstellar medium. Here, we investigate the effects of a broad grain-size distribution on the chemistry of dust-grain surfaces and the subsequent build-up of molecular ices on the grains, using a three-phase gas-grain chemical model of a quiescent dark cloud. We include an explicit treatment of the grain temperatures, governed both by the visual extinction of the cloud and the size of each individual grain-size population. We find that the temperature difference plays a significant role in determining the total bulk ice composition across the grain-size distribution, while the effects of geometrical differences between size populations appear marginal. We also consider collapse from a diffuse to a dark cloud, allowing dust temperatures to fall. Under the initial diffuse conditions, small grains are too warm to promote grain-mantle build-up, with most ices forming on the mid-sized grains. As collapse proceeds, the more abundant, smallest grains cool and become the dominant ice carriers; the large population of small grains means that this ice is distributed across many grains, with perhaps no more than 40 monolayers of ice each (versus several hundred assuming a single grain size). This effect may be important for the subsequent processing and desorption of the ice during the hot-core phase of star formation, exposing a significant proportion of the ice to the gas phase, increasing the importance of ice-surface chemistry and surface–gas interactions.

The Effects of Grain Size and Temperature Distributions on the Formation of Interstellar Ice Mantles

Science.gov (United States)

Pauly, Tyler; Garrod, Robin T.

2016-02-01

Computational models of interstellar gas-grain chemistry have historically adopted a single dust-grain size of 0.1 micron, assumed to be representative of the size distribution present in the interstellar medium. Here, we investigate the effects of a broad grain-size distribution on the chemistry of dust-grain surfaces and the subsequent build-up of molecular ices on the grains, using a three-phase gas-grain chemical model of a quiescent dark cloud. We include an explicit treatment of the grain temperatures, governed both by the visual extinction of the cloud and the size of each individual grain-size population. We find that the temperature difference plays a significant role in determining the total bulk ice composition across the grain-size distribution, while the effects of geometrical differences between size populations appear marginal. We also consider collapse from a diffuse to a dark cloud, allowing dust temperatures to fall. Under the initial diffuse conditions, small grains are too warm to promote grain-mantle build-up, with most ices forming on the mid-sized grains. As collapse proceeds, the more abundant, smallest grains cool and become the dominant ice carriers; the large population of small grains means that this ice is distributed across many grains, with perhaps no more than 40 monolayers of ice each (versus several hundred assuming a single grain size). This effect may be important for the subsequent processing and desorption of the ice during the hot-core phase of star formation, exposing a significant proportion of the ice to the gas phase, increasing the importance of ice-surface chemistry and surface-gas interactions.

Formaldehyde: a candidate toxic air contaminant. Final report

Energy Technology Data Exchange (ETDEWEB)

Frye, B.; Parker, T.

1988-03-01

Formaldehyde (HCHO) is a gas widely used in adhesives and resins, textiles, embalming fluids, fungicides, air fresheners, and cosmetics. It is directly emitted into the ambient outdoor air from vehicular and stationary sources, and is also produced in the atmosphere from other substances by photochemical smog processes. The International Agency for Research on Cancer (IARC) has determined that there is sufficient evidence for carcinogenicity of formaldehyde to animals, and limited evidence for carcinogenicity to humans. EPA classifies formaldehyde as a probable human carcinogen with a one in a million risk concentration of 0.08 ppb.

Chemosorption sampling and analysis of formaldehyde in air. Influence on recovery during the simultaneous sampling of formaldehyde, phenol, furfural and furfuryl alcohol

Energy Technology Data Exchange (ETDEWEB)

Andersson, K.; Hallgren, C.; Levin, J.O.; Nilsson, C.A.

1981-12-01

A method based on trapping formaldehyde on a 2,4-dinitrodinitrophenylhydrazine-coated porous polymer (Amberlite XAD-2) was evaluated for air sampling in occupational environments. The aldehyde is converted to its 2,4-dinitrophenylhydrazone on the adsorbent. The influence of some organic compounds which often occur together with formaldehyde-furfural, phenol and furfuryl alcohol--was studied. The results show that the method allows the sampling of formaldehyde in the range 0.01--1.0 mg/m3 of air, based on a 3-1 (15 min) sample and a coating of 1%. Furfural, phenol, and furfuryl alcohol do not interfere and may be conveniently sampled at the same time. Formaldehyde and furfural hydrazones were analyzed by high-performance liquid chromatography, phenol and furfuryl alcohol by gas chromatography.

Formaldehyde cross-linking and structural proteomics: Bridging the gap.

Science.gov (United States)

Srinivasa, Savita; Ding, Xuan; Kast, Juergen

2015-11-01

Proteins are dynamic entities constantly moving and altering their structures based on their functions and interactions inside and outside the cell. Formaldehyde cross-linking combined with mass spectrometry can accurately capture interactions of these rapidly changing biomolecules while maintaining their physiological surroundings. Even with its numerous established uses in biology and compatibility with mass spectrometry, formaldehyde has not yet been applied in structural proteomics. However, formaldehyde cross-linking is moving toward analyzing tertiary structure, which conventional cross-linkers have already accomplished. The purpose of this review is to describe the potential of formaldehyde cross-linking in structural proteomics by highlighting its applications, characteristics and current status in the field. Copyright © 2015 Elsevier Inc. All rights reserved.

21 CFR 177.1900 - Urea-formaldehyde resins in molded articles.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Urea-formaldehyde resins in molded articles. 177... for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1900 Urea-formaldehyde resins in molded articles. Urea-formaldehyde resins may be safely used as the food-contact surface...

Preliminary study: Formaldehyde exposure in laboratories of Sharjah university in UAE

OpenAIRE

Ahmed, Hafiz Omer

2011-01-01

Objectives : Laboratory technicians, students, and instructors are at high risk, because they deal with chemicals including formaldehyde. Thus, this preliminary study was conducted to measure the concentration of formaldehyde in the laboratories of the University of Sharjah in UAE. Materials and Methods: Thirty-two air samples were collected and analyzed for formaldehyde using National Institute for Occupational Safety and Health (NIOSH) method 3500. In this method, formaldehyde reacts with c...

Effects of Sodium Selenite on Formaldehyde Induced Renal Toxicity in Mice

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Shabnam Mohammadi 1,2 * , Maryam Moghimian 3, Hanieh Torabzadeh 4, Mahla Langari 4, Roghayeh Nazeri 4, Zahra Karimi 4, Elham Sangari 4, Najmeh Jagarmi 5, Alireza Mohammad Zadeh 3, Mehdi Karimi 7, Kamyar Tavakkoli 8, Ali Delshad 9, Fatemeh Mohammadzadeh 3, Majid Ghayour-Mobarhan 10

2016-12-01

Full Text Available Background: Formaldehyde is widely used for industrial applications. Renal injury is an adverse effect associated with formaldehyde. Few studies have explored the potential benefits of protective factors on formaldehyde induced renal toxicity. This study evaluated the dose dependent effects of sodium selenite on the biochemical and histopathological effects of formaldehyde on murine kidney. Methods: Forty eight adult Balb/c male mice were randomized into six groups: a control group, a formaldehyde group and experimental III-VI groups. Formaldehyde group was injected with 10 mg/kg formaldehyde and groups III-VI received intraperitoneally doses of 0.1, 0.2, 0.4, 0.8 mg/kg selenium. After two weeks, a stereological study was done in accordance with the principle of Cavalieri and serum concentrations of urea and creatinine were measured. Data were analyzed using ANOVA and SPSS software. Results: Glomerosclerosis, necrosis and vacuolization were observed in the convoluted tubules of animals treated with formaldehyde. The biochemical markers, volume and count of glomeruli in the group treated with formaldehyde was significantly difference compared to the control group (P<0.05. The volume of the glomeruli in the group treated with 0.2 and 0.4 mg selenium and urea level in the group treated with 0.4 and 0.1 mg/kg selenium was significantly difference compared to the control group (P <0.05. The count of glomeruli and creatinine level in the selenium group was significantly difference compared to the control group (P ≤ 0.0001. Conclusions: A dose of 0.2 mg/kg of sodium selenite caused partial protective effect on the renal tissue and function in exposed to formaldehyde.

Exposure to formaldehyde: a challenge of occupational health significance

International Nuclear Information System (INIS)

Kaonga, K.

2009-01-01

The use of formaldehyde as the fixative for general microscopic demonstration of tissues in medical laboratory establishments is as significant as the diagnosis of the underlying ailment. Instantaneous human exposure to formaldehyde elicits symptoms that may include watery eyes, headache, inflamed throat and dyspnea. The gaseous chemical is toxic, allergenic and carcinogenic. A study to determine the incidence of human exposure to formaldehyde was carried out at the University Teaching Hospital in Lusaka, Zambia from January to December, 2007. Anonymous questionnaires on various aspects of human exposure to formaldehyde were given to laboratory technical personnel. Exposure to formaldehyde was determined using general consideration model comprising points awarded to participants according to their responses. Five points represented the maximum level of exposure, while one point denoted the minimum encounter. There were 8 incidents of formaldehyde pollution, with five being emissions from 210-litre formalin receptacles whose stoppers were inadvertently left loose overnight, while three involved accidental breakage of Winchester bottles of formalin. A total of 115 people were exposed during the year. Fifteen (13.0 percent) participants scored one point each, while 20 (17.4 percent) participants obtained 2 points each. Thirty-five (30.4 percent) participants got 3 points each, while 30 (26.0 percent) participants received 4 points each. Twenty-five (21.7 percent) participants attained 5 points each. Human exposure to formaldehyde is an issue of occupational health concern. Participants with a score of 3 points or more need regular medical check ups in order to safeguard their health. Programs on effective management of hazardous chemicals are worth setting up.(author)

Formation of outflow channels on Mars: Testing the origin of Reull Vallis in Hesperia Planum by large-scale lava-ice interactions and top-down melting

Science.gov (United States)

Cassanelli, James P.; Head, James W.

2018-05-01

The Reull Vallis outflow channel is a segmented system of fluvial valleys which originates from the volcanic plains of the Hesperia Planum region of Mars. Explanation of the formation of the Reull Vallis outflow channel by canonical catastrophic groundwater release models faces difficulties with generating sufficient hydraulic head, requiring unreasonably high aquifer permeability, and from limited recharge sources. Recent work has proposed that large-scale lava-ice interactions could serve as an alternative mechanism for outflow channel formation on the basis of predictions of regional ice sheet formation in areas that also underwent extensive contemporaneous volcanic resurfacing. Here we assess in detail the potential formation of outflow channels by large-scale lava-ice interactions through an applied case study of the Reull Vallis outflow channel system, selected for its close association with the effusive volcanic plains of the Hesperia Planum region. We first review the geomorphology of the Reull Vallis system to outline criteria that must be met by the proposed formation mechanism. We then assess local and regional lava heating and loading conditions and generate model predictions for the formation of Reull Vallis to test against the outlined geomorphic criteria. We find that successive events of large-scale lava-ice interactions that melt ice deposits, which then undergo re-deposition due to climatic mechanisms, best explains the observed geomorphic criteria, offering improvements over previously proposed formation models, particularly in the ability to supply adequate volumes of water.

Influence of indoor formaldehyde pollution on respiratory system ...

African Journals Online (AJOL)

Background The decoration of interior spaces can lead to dangerous levels of indoor formaldehyde pollution. Exposure to indoor air pollution may be responsible for nearly 2 million deaths per year in developing countries. Objectives To assess the prevalence of indoor formaldehyde pollution caused by decoration and ...

Electrodeposition of gold from formaldehyde-sulfite baths: bath stability and deposits characterization

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Juliana L. Cardoso

2011-01-01

Full Text Available It was investigated Au(I-sulfite baths containing formaldehyde. As a result, high stability was achieved for baths containing formaldehyde concentration close to 10 mL L-1 with a lifetime superior to 600 days. On the other hand, cyclic voltammograms indicated that the increase of formaldehyde concentration in the bath promotes decreasing of the maximum cathodic current, so that, if the formaldehyde concentration is high, the surface areal concentration of gold will be low. Also, the lowest surface roughness was obtained for 10 mL L-1 of formaldehyde.

Removal of formaldehyde from gas streams via packed-bed dielectric barrier discharge plasmas

International Nuclear Information System (INIS)

Ding Huixian; Zhu Aimin; Yang Xuefeng; Li Cuihong; Xu Yong

2005-01-01

Formaldehyde is a major indoor air pollutant and can cause serious health disorders in residents. This work reports the removal of formaldehyde from gas streams via alumina-pellet-filled dielectric barrier discharge plasmas at atmospheric pressure and 70 deg. C. With a feed gas mixture of 140 ppm HCHO, 21.0% O 2 , 1.0% H 2 O in N 2 , ∼92% of formaldehyde can be effectively destructed at GHSV (gas flow volume per hour per discharge volume) of 16 500 h -1 and E in = 108 J l -1 . An increase in the specific surface area of the alumina pellets enhances the HCHO removal, and this indicates that the adsorbed HCHO species may have a lower C-H bond breakage energy. Based on an examination of the influence of gas composition on the removal efficiency, the primary destruction pathways, besides the reactions initiated by discharge-generated radicals, such as O, H, OH and HO 2 , may include the consecutive dissociations of HCHO molecules and HCO radicals through their collisions with vibrationally- and electronically-excited metastable N 2 species. The increase of O 2 content in the inlet gas stream is able to diminish the CO production and to promote the formation of CO 2 via O-atom or HO 2 -radical involved reactions

Combined effect of formaldehyde and gamma-irradiation. Vitamin complex effect

International Nuclear Information System (INIS)

Ban'kovskij, A.A.; El'chaninova, M.A.

1996-01-01

Combined inhalation effect of formaldehyde and gamma-irradiation on the activities of alcohol and aldehyde dehydrogenases in rat lung tissue was studied. The possibility of fitting the parameters studied by the vitamin PP, A and E and complex was shown. At investigation of white rats in conditions of formaldehyde inhalation in concentration 10 mg/m 3 and gamma-irradiation by dose 0.25 Gy the changes of activities of alcohol and aldehyde dehydrogenases in the rat lung tissue were detected. An injection of PP, A and E vitamin complex after combined effect of formaldehyde and gamma-irradiation contributes to normalization of studied parameters. The K(C -1 ) constant is reduced. On this basis it is proposed that in such conditions formaldehyde stabilizes membranes and protects important metabolic processes against damages. Thus, vitamin complex is capable to level a toxic combined effect of formaldehyde and gamma-irradiation. 9 refs., 1 tab

Formaldehyde in the Galactic Centre

International Nuclear Information System (INIS)

Cohen, R.J.; Few, R.W.

1981-01-01

Formaldehyde 6-cm absorption in the direction of the Galactic Centre has been surveyed using the Jodrell Bank MK II radio telescope (beam-width 10 x 9 arcmin). The observations sample the region - 2 0 = 0 and - 0 0 .5 = 0 .5, with a velocity range of 620 km s -1 , a velocity resolution of 2.1 km s -1 and an rms noise level of approximately 0.03 K. The data are presented as contour maps showing line temperature as a function of latitude and velocity (b-V maps) and as a function of longitude and velocity (l-V maps). Similar maps of the line-to-continuum ratio are also presented. The radial distribution of formaldehyde (H 2 CO) in the Galactic Centre region is derived using two different kinematic models which give similar results. Formaldehyde is strongly concentrated in the Galactic Centre in a layer of latitude extent approximately 0 0 .5 and longitude extent approximately 4 0 which contains one quarter of all the H 2 CO in the Galaxy. The distribution is centred on l approximately 1 0 . The individual H 2 CO features are described in detail. (author)

Release rate of diazinon from microcapsule based on melamine formaldehyde

Science.gov (United States)

Noviana Utami C., S.; Rochmadi

2018-04-01

The microcapsule containing diazinon as the core material and melamine formaldehyde as the membrane material have been synthesized by in situ polymerization method. The microcapsule membrane in this research is melamine formaldehyde (MF). This research aims to study the effect of pH and temperature on the release rate of diazinon from microcapsule based on melamine formaldehyde in aqueous medium. The results showed that pH and temperature has little effect on the release rate of diazinon from microcapsule based on melamine formaldehyde. This is due to the diffusion through the microcapsule membrane is not influenced by the pH and temperature of the solution outside of microcapsule.

Thermodynamic and Dynamic Aspects of Ice Nucleation

Science.gov (United States)

Barahona, Donifan

2018-01-01

It is known that ice nucleating particles (INP) immersed within supercooled droplets promote the formation of ice. Common theoretical models used to represent this process assume that the immersed particle lowers the work of ice nucleation without significantly affecting the dynamics of water in the vicinity of the particle. This is contrary to evidence showing that immersed surfaces significantly affect the viscosity and diffusivity of vicinal water. To study how this may affect ice formation this work introduces a model linking the ice nucleation rate to the modification of the dynamics and thermodynamics of vicinal water by immersed particles. It is shown that INP that significantly reduce the work of ice nucleation also pose strong limitations to the growth of the nascent ice germs. This leads to the onset of a new ice nucleation regime, called spinodal ice nucleation, where the dynamics of ice germ growth instead of the ice germ size determines the nucleation rate. Nucleation in this regime is characterized by an enhanced sensitivity to particle area and cooling rate. Comparison of the predicted ice nucleation rate against experimental measurements for a diverse set of species relevant to cloud formation suggests that spinodal ice nucleation may be common in nature.

Formation of ice XII at low temperatures and high pressures

International Nuclear Information System (INIS)

Schober, H.; Koza, M.; Toelle, A.; Fujara, F.

1999-01-01

Complete text of publication follows. Solid water features a large variety of crystalline as well as two amorphous phases. The versatility of water's behavior has been reinforced recently by the identification of still another form of crystalline ice [1]. Ice XII was obtained by cooling liquid water to 260 K at a pressure of 5.5 kbar. Ice XII could be produced in a completely different region of water's phase diagram [2]. Using a. piston-cylinder apparatus ice XII was formed during the production of high-density amorphous ice (HDA) at 77 K as described previously [3]. The amount of crystalline ice XII contamination within the HDA sample varies in a so far unpredictable way with both extremes, i.e. pure HDA as well as pure ice XII. realized. Our results indicate that water's phase diagram needs modification in the region assigned to HDA. Ice XII is characterized as well as its transition towards cubic ice by elastic and inelastic neutron scattering. (author)

Ice nucleation in sulfuric acid/organic aerosols: implications for cirrus cloud formation

Directory of Open Access Journals (Sweden)

M. R. Beaver

2006-01-01

Full Text Available Using an aerosol flow tube apparatus, we have studied the effects of aliphatic aldehydes (C3 to C10 and ketones (C3 and C9 on ice nucleation in sulfuric acid aerosols. Mixed aerosols were prepared by combining an organic vapor flow with a flow of sulfuric acid aerosols over a small mixing time (~60 s at room temperature. No acid-catalyzed reactions were observed under these conditions, and physical uptake was responsible for the organic content of the sulfuric acid aerosols. In these experiments, aerosol organic content, determined by a Mie scattering analysis, was found to vary with the partial pressure of organic, the flow tube temperature, and the identity of the organic compound. The physical properties of the organic compounds (primarily the solubility and melting point were found to play a dominant role in determining the inferred mode of nucleation (homogenous or heterogeneous and the specific freezing temperatures observed. Overall, very soluble, low-melting organics, such as acetone and propanal, caused a decrease in aerosol ice nucleation temperatures when compared with aqueous sulfuric acid aerosol. In contrast, sulfuric acid particles exposed to organic compounds of eight carbons and greater, of much lower solubility and higher melting temperatures, nucleate ice at temperatures above aqueous sulfuric acid aerosols. Organic compounds of intermediate carbon chain length, C4-C7, (of intermediate solubility and melting temperatures nucleated ice at the same temperature as aqueous sulfuric acid aerosols. Interpretations and implications of these results for cirrus cloud formation are discussed.

Ice formation in altocumulus clouds over Leipzig: Remote sensing measurements and detailed model simulations

Science.gov (United States)

Simmel, Martin; Bühl, Johannes; Ansmann, Albert; Tegen, Ina

2014-05-01

Over Leipzig, altocumulus clouds are frequently observed using a suite of remote sensing instruments. These observations cover a wide range of heights, temperatures, and microphysical properties of the clouds ranging from purely liquid to heavily frozen. For the current study, two cases were chosen to test the sensitivity of these clouds with respect to several microphysical and dynamical parameters such as aerosol properties (CCN, IN), ice particle shape as well as turbulence. The mixed-phase spectral microphysical model SPECS was coupled to a dynamical model of the Asai-Kasahara type resulting in the model system AK-SPECS. The relatively simple dynamics allows for a fine vertical resolution needed for the rather shallow cloud layers observed. Additionally, the proper description of hydrometeor sedimentation is important especially for the fast growing ice crystals to realistically capture their interaction with the vapour and liquid phase (Bergeron-Findeisen process). Since the focus is on the cloud microphysics, the dynamics in terms of vertical velocity profile is prescribed for the model runs and the feedback of the microphysics on dynamics by release or consumption of latent heat due to phase transfer is not taken into account. The microphysics focuses on (1) ice particle shape allowing hexagonal plates and columns with size-dependant axis ratios and (2) the ice nuclei (IN) budget realized with a prognostic temperature resolved field of potential IN allowing immersion freezing only when active IN and supercooled drops above a certain size threshold are present within a grid cell. Sensitivity studies show for both cases that ice particle shape seems to have the major influence on ice mass formation under otherwise identical conditions. This is due to the effect (1) on terminal fall velocity of the individual ice particle allowing for longer presence times in conditions supersaturated with respect to ice and (2) on water vapour deposition which is enhanced due

Modeling formalin fixation and histological processing with ribonuclease A: effects of ethanol dehydration on reversal of formaldehyde cross-links.

Science.gov (United States)

Fowler, Carol B; O'Leary, Timothy J; Mason, Jeffrey T

2008-07-01

Understanding the chemistry of protein modification by formaldehyde fixation and subsequent tissue processing is central to developing improved methods for antigen retrieval in immunohistochemistry and for recovering proteins from formalin-fixed, paraffin-embedded (FFPE) tissues for proteomic analysis. Our initial studies of single proteins, such as bovine pancreatic ribonuclease A (RNase A), in 10% buffered formalin solution revealed that upon removal of excess formaldehyde, monomeric RNase A exhibiting normal immunoreactivity could be recovered by heating at 60 degrees C for 30 min at pH 4. We next studied tissue surrogates, which are gelatin-like plugs of fixed proteins that have sufficient physical integrity to be processed using normal tissue histology. Following histological processing, proteins could be extracted from the tissue surrogates by combining heat, detergent, and a protein denaturant. However, gel electrophoresis revealed that the surrogate extracts contained a mixture of monomeric and multimeric proteins. This suggested that during the subsequent steps of tissue processing protein-formaldehyde adducts undergo further modifications that are not observed in aqueous proteins. As a first step toward understanding these additional modifications we have performed a comparative evaluation of RNase A following fixation in buffered formaldehyde alone and after subsequent dehydration in 100% ethanol by combining gel electrophoresis, chemical modification, and circular dichroism spectroscopic studies. Our results reveal that ethanol-induced rearrangement of the conformation of fixed RNase A leads to protein aggregation through the formation of large geometrically compatible hydrophobic beta-sheets that are likely stabilized by formaldehyde cross-links, hydrogen bonds, and van der Waals interactions. It requires substantial energy to reverse the formaldehyde cross-links within these sheets and regenerate protein monomers free of formaldehyde modifications

Formation of Methylamine and Ethylamine in Extraterrestrial Ices and Their Role as Fundamental Building Blocks of Proteinogenic α -amino Acids

Energy Technology Data Exchange (ETDEWEB)

Förstel, Marko; Bergantini, Alexandre; Maksyutenko, Pavlo; Góbi, Sándor; Kaiser, Ralf I., E-mail: ralfk@hawaii.edu [W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, Hawaii, HI, 96822 (United States)

2017-08-10

The –CH–NH{sub 2} moiety represents the fundamental building block of all proteinogenic amino acids, with the cyclic amino acid proline being a special case (–CH–NH– in proline). Exploiting a chemical retrosynthesis, we reveal that methylamine (CH{sub 3}NH{sub 2}) and/or ethylamine (CH{sub 3}CH{sub 2}NH{sub 2}) are essential precursors in the formation of each proteinogenic amino acid. In the present study we elucidate the abiotic formation of methylamine and ethylamine from ammonia (NH{sub 3}) and methane (CH{sub 4}) ices exposed to secondary electrons generated by energetic cosmic radiation in cometary and interstellar model ices. Our experiments show that methylamine and ethylamine are crucial reaction products in irradiated ices composed of ammonia and methane. Using isotopic substitution studies we further obtain valuable information on the specific reaction pathways toward methylamine. The very recent identification of methylamine and ethylamine together with glycine in the coma of 67P/Churyumov–Gerasimenko underlines their potential to the extraterrestrial formation of amino acids.

A survey of formaldehyde in the Cepheus OB3 molecular cloud

International Nuclear Information System (INIS)

Few, R.W.; Cohen, R.J.

1983-01-01

The 1 11 - 1 10 absorption line of formaldehyde at 6-cm wavelength has been surveyed over the region of the Cepheus OB3 molecular cloud, using the Jodrell Bank Mk II radio telescope (beamwidth 9 x 10 arcmin 2 ). The measurements have a velocity resolution of 0.27 km s - 1 and an rms noise level of approx. 0.01 K. The formaldehyde has a very clumpy distribution which is broadly similar to the CO distribution found by Sargent. A total molecular mass of 1.9 x 10 4 solar masses is implied by the formaldehyde measurements. Cepheus A is not the dominant concentration in the formaldehyde map. The most massive formaldehyde concentration is Cepheus C, which has a mass of 3600 solar masses. It appears to be stabilized by rotation. (author)

Teratogenic effect of formaldehyde in rabbits

Directory of Open Access Journals (Sweden)

A. A. Al–Saraj

2009-01-01

Full Text Available Thirty three pregnant rabbits were exposed to vapour of 10% formaldehyde (12 ppm throughout the gestation period to know its effect on newborns. The results showed no abortion or foetal mortality but there were some anomalies (23.8% among the newborns rabbits which includes: meromelia (6.8%, encephalocele (6.1%, Oligodactyly (4.1%, Umbilical hernia (3.4% and Short tail (3.4%; besides that small for date and decrease in the body weight of the newborns were also noticed. These findings suggest that formaldehyde is a teratogenic agent.

Contact allergic dermatitis from melamine formaldehyde resins in a patient with a negative patch-test reaction to formaldehyde.

Science.gov (United States)

García Gavin, Juan; Loureiro Martinez, Manuel; Fernandez-Redondo, Virginia; Seoane, Maria-José; Toribio, Jaime

2008-01-01

Melamine paper is a basic material used in the furniture industry for home and office interiors. Contact allergic dermatitis from melamine formaldehyde resins (MFRs) should be considered in patients who work on melamine paper impregnation lines. We report a case of a 28-year-old female plywood worker who developed eczema on the dorsal side of her hands and wrists after 2 years of working on the melamine paper impregnation line. She had a relevant positive patch-test reaction to MFR, with a negative reaction to formaldehyde. Contact dermatitis due to MFR is not common, and it is usually related to products that are not fully cured or to close contact with intermediate products on the assembly line. Formaldehyde release from MFR can explain most of the positive responses. To our knowledge, this is the first report of MFR contact allergic dermatitis in a worker on a melamine paper impregnation line.

Effect of formaldehyde on the upper respiratory tract _ormal flora of ...

African Journals Online (AJOL)

Background: Formaldehyde is a chemical that is used to fix a tissue after death or removal from the body to prevent autolysis and putrefaction. Exposure to formaldehyde can occur as a result of occupation. Objective: To determine the effect of the formaldehyde on the throat and nasal flora of upper respiratory tract of rabbits ...

Sol-gel based sensor for selective formaldehyde determination

Energy Technology Data Exchange (ETDEWEB)

Bunkoed, Opas [Trace Analysis and Biosensor Research Center, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Department of Chemistry and Center for Innovation in Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Davis, Frank [Cranfield Health, Cranfield University, Bedford MK43 0AL (United Kingdom); Kanatharana, Proespichaya, E-mail: proespichaya.K@psu.ac.th [Trace Analysis and Biosensor Research Center, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Department of Chemistry and Center for Innovation in Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Thavarungkul, Panote [Trace Analysis and Biosensor Research Center, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Department of Physics, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Higson, Seamus P.J., E-mail: s.p.j.higson@cranfield.ac.uk [Cranfield Health, Cranfield University, Bedford MK43 0AL (United Kingdom)

2010-02-05

We report the development of transparent sol-gels with entrapped sensitive and selective reagents for the detection of formaldehyde. The sampling method is based on the adsorption of formaldehyde from the air and reaction with {beta}-diketones (for example acetylacetone) in a sol-gel matrix to produce a yellow product, lutidine, which was detected directly. The proposed method does not require preparation of samples prior to analysis and allows both screening by visual detection and quantitative measurement by simple spectrophotometry. The detection limit of 0.03 ppmv formaldehyde is reported which is lower than the maximum exposure concentrations recommended by both the World Health Organisation (WHO) and the Occupational Safety and Health Administration (OSHA). This sampling method was found to give good reproducibility, the relative standard deviation at 0.2 and 1 ppmv being 6.3% and 4.6%, respectively. Other carbonyl compounds i.e. acetaldehyde, benzaldehyde, acetone and butanone do not interfere with this analytical approach. Results are provided for the determination of formaldehyde in indoor air.

Sol-gel based sensor for selective formaldehyde determination

International Nuclear Information System (INIS)

Bunkoed, Opas; Davis, Frank; Kanatharana, Proespichaya; Thavarungkul, Panote; Higson, Seamus P.J.

2010-01-01

We report the development of transparent sol-gels with entrapped sensitive and selective reagents for the detection of formaldehyde. The sampling method is based on the adsorption of formaldehyde from the air and reaction with β-diketones (for example acetylacetone) in a sol-gel matrix to produce a yellow product, lutidine, which was detected directly. The proposed method does not require preparation of samples prior to analysis and allows both screening by visual detection and quantitative measurement by simple spectrophotometry. The detection limit of 0.03 ppmv formaldehyde is reported which is lower than the maximum exposure concentrations recommended by both the World Health Organisation (WHO) and the Occupational Safety and Health Administration (OSHA). This sampling method was found to give good reproducibility, the relative standard deviation at 0.2 and 1 ppmv being 6.3% and 4.6%, respectively. Other carbonyl compounds i.e. acetaldehyde, benzaldehyde, acetone and butanone do not interfere with this analytical approach. Results are provided for the determination of formaldehyde in indoor air.

Effect of Adsorption on Ice Surfaces on the Composition of Enceladus' Plumes: Partitioning of Oxygen-Bearing Organics

Science.gov (United States)

Bouquet, A.; Teolis, B. D.; Waite, J. H., Jr.

2017-12-01

Introduction: The plumes of Enceladus offer an opportunity to access a sample of water from its internal ocean. However, to gain valuable insights into the ocean's composition, it is necessary to take into account any possible process that would alter the mixture between the water table and the geysers. The adsorption of refractory compounds on the ice walls in the vents could partition them depending on their properties. Evaluating the effect of this fractionation is critical in anticipating which organics could be detected by a future mission. Models: We used a model using the temkin isotherm and published experimental desorption energies for our compounds of interest. The model calculates how the coverage of an ice surface exposed to the flow can evolve with time and what is the final composition of the adsorbed mixture is. The model considers the ice walls and the ice grains, as the latter have the potential to gather the most sticky compounds and put them within reach of sampling by a spacecraft. Our list of species included formaldehyde, methanol, acetic acid, formic acid, ethanol, butanol, benzene and hexanal.Results: We found that simple hydrocarbons have a very short residence time on ice, and are expected to stay in gas phase. Oxygen-bearing organic compounds, though, stick to the ice and will be concentrated on the walls and ice grains, with the exception of formaldehyde. With the species listed above originally in equal abundance in gas phase, we found the ice surface to hold mostly formic acid, acetic acid and butanol, with a small amount of ethanol and hexanal. The high number of collisions in the closed space of a 1 meter wide vent allows for a gas/adsorbed equilibration within a second. Way forward: The possible impact of ammonia, detected in the plumes, is unknown. Ammonia can accumulate on the ice surface and influence adsorption of other species, and potentially create a liquid layer by depressing the freezing point of water. The impact of these

Evidence for middle Eocene Arctic sea ice from diatoms and ice-rafted debris.

Science.gov (United States)

Stickley, Catherine E; St John, Kristen; Koç, Nalân; Jordan, Richard W; Passchier, Sandra; Pearce, Richard B; Kearns, Lance E

2009-07-16

Oceanic sediments from long cores drilled on the Lomonosov ridge, in the central Arctic, contain ice-rafted debris (IRD) back to the middle Eocene epoch, prompting recent suggestions that ice appeared in the Arctic about 46 million years (Myr) ago. However, because IRD can be transported by icebergs (derived from land-based ice) and also by sea ice, IRD records are restricted to providing a history of general ice-rafting only. It is critical to differentiate sea ice from glacial (land-based) ice as climate feedback mechanisms vary and global impacts differ between these systems: sea ice directly affects ocean-atmosphere exchanges, whereas land-based ice affects sea level and consequently ocean acidity. An earlier report assumed that sea ice was prevalent in the middle Eocene Arctic on the basis of IRD, and although somewhat preliminary supportive evidence exists, these data are neither comprehensive nor quantified. Here we show the presence of middle Eocene Arctic sea ice from an extraordinary abundance of a group of sea-ice-dependent fossil diatoms (Synedropsis spp.). Analysis of quartz grain textural characteristics further supports sea ice as the dominant transporter of IRD at this time. Together with new information on cosmopolitan diatoms and existing IRD records, our data strongly suggest a two-phase establishment of sea ice: initial episodic formation in marginal shelf areas approximately 47.5 Myr ago, followed approximately 0.5 Myr later by the onset of seasonally paced sea-ice formation in offshore areas of the central Arctic. Our data establish a 2-Myr record of sea ice, documenting the transition from a warm, ice-free environment to one dominated by winter sea ice at the start of the middle Eocene climatic cooling phase.

A Detailed Geophysical Investigation of the Grounding of Henry Ice Rise, with Implications for Holocene Ice-Sheet Extent.

Science.gov (United States)

Wearing, M.; Kingslake, J.

2017-12-01

It is generally assumed that since the Last Glacial Maximum the West Antarctic Ice Sheet (WAIS) has experienced monotonic retreat of the grounding line (GL). However, recent studies have cast doubt on this assumption, suggesting that the retreat of the WAIS grounding line may have been followed by a significant advance during the Holocene in the Weddell and Ross Sea sectors. Constraining this evolution is important as reconstructions of past ice-sheet extent are used to spin-up predictive ice-sheet models and correct mass-balance observations for glacial isostatic adjustment. Here we examine in detail the formation of the Henry Ice Rise (HIR), which ice-sheet model simulations suggest played a key role in Holocene ice-mass changes in the Weddell Sea sector. Observations from a high-resolution ground-based, ice-penetrating radar survey are best explained if the ice rise formed when the Ronne Ice Shelf grounded on a submarine high, underwent a period of ice-rumple flow, before the GL migrated outwards to form the present-day ice rise. We constrain the relative chronology of this evolution by comparing the alignment and intersection of isochronal internal layers, relic crevasses, surface features and investigating the dynamic processes leading to their complex structure. We also draw analogies between HIR and the neighbouring Doake Ice Rumples. The date of formation is estimated using vertical velocities derived with a phase-sensitive radio-echo sounder (pRES). Ice-sheet models suggest that the formation of the HIR and other ice rises may have halted and reversed large-scale GL retreat. Hence the small-scale dynamics of these crucial regions could have wide-reaching consequences for future ice-sheet mass changes and constraining their formation and evolution further would be beneficial. One stringent test of our geophysics-based conclusions would be to drill to the bed of HIR to sample the ice for isotopic analysis and the bed for radiocarbon analysis.

ON THE FORMATION OF AMIDE POLYMERS VIA CARBONYL–AMINO GROUP LINKAGES IN ENERGETICALLY PROCESSED ICES OF ASTROPHYSICAL RELEVANCE

Energy Technology Data Exchange (ETDEWEB)

Förstel, Marko; Maksyutenko, Pavlo; Jones, Brant M.; Kaiser, Ralf I. [Department of Chemistry, University of Hawaii, 2545 McCarthy Mall, 96822 HI (United States); Sun, Bing J.; Lee, Huan C.; Chang, Agnes H. H., E-mail: ralfk@hawaii.edu, E-mail: hhchang@mail.ndhu.edu.tw [Department of Chemistry, National Dong Hwa University, Shoufeng, Hualien 974, Taiwan (China)

2016-04-01

We report on the formation of organic amide polymers via carbonyl–amino group linkages in carbon monoxide and ammonia bearing energetically processed ices of astrophysical relevance. The first group comprises molecules with one carboxyl group and an increasing number of amine moieties starting with formamide (45 u), urea (60 u), and hydrazine carboxamide (75 u). The second group consists of species with two carboxyl (58 u) and up to three amine groups (73 u, 88 u, and 103 u). The formation and polymerization of these linkages from simple inorganic molecules via formamide und urea toward amide polymers is discussed in an astrophysical and astrobiological context. Our results show that long chain molecules, which are closely related to polypeptides, easily form by energetically processing simple, inorganic ices at very low temperatures and can be released into the gas phase by sublimation of the ices in star-forming regions. Our experimental results were obtained by employing reflectron time-of-flight mass spectroscopy, coupled with soft, single photon vacuum ultraviolet photoionization; they are complemented by theoretical calculations.

ON THE FORMATION OF AMIDE POLYMERS VIA CARBONYL–AMINO GROUP LINKAGES IN ENERGETICALLY PROCESSED ICES OF ASTROPHYSICAL RELEVANCE

International Nuclear Information System (INIS)

Förstel, Marko; Maksyutenko, Pavlo; Jones, Brant M.; Kaiser, Ralf I.; Sun, Bing J.; Lee, Huan C.; Chang, Agnes H. H.

2016-01-01

We report on the formation of organic amide polymers via carbonyl–amino group linkages in carbon monoxide and ammonia bearing energetically processed ices of astrophysical relevance. The first group comprises molecules with one carboxyl group and an increasing number of amine moieties starting with formamide (45 u), urea (60 u), and hydrazine carboxamide (75 u). The second group consists of species with two carboxyl (58 u) and up to three amine groups (73 u, 88 u, and 103 u). The formation and polymerization of these linkages from simple inorganic molecules via formamide und urea toward amide polymers is discussed in an astrophysical and astrobiological context. Our results show that long chain molecules, which are closely related to polypeptides, easily form by energetically processing simple, inorganic ices at very low temperatures and can be released into the gas phase by sublimation of the ices in star-forming regions. Our experimental results were obtained by employing reflectron time-of-flight mass spectroscopy, coupled with soft, single photon vacuum ultraviolet photoionization; they are complemented by theoretical calculations

The margin of exposure to formaldehyde in alcoholic beverages.

Science.gov (United States)

Monakhova, Yulia B; Jendral, Julien A; Lachenmeier, Dirk W

2012-06-01

Formaldehyde has been classified as carcinogenic to humans (WHO IARC group 1). It causes leukaemia and nasopharyngeal cancer, and was described to regularly occur in alcoholic beverages. However, its risk associated with consumption of alcohol has not been systematically studied, so this study will provide the first risk assessment of formaldehyde for consumers of alcoholic beverages.Human dietary intake of formaldehyde via alcoholic beverages in the European Union was estimated based on WHO alcohol consumption data and literature on formaldehyde contents of different beverage groups (beer, wine, spirits, and unrecorded alcohol). The risk assessment was conducted using the margin of exposure (MOE) approach with benchmark doses (BMD) for 10 % effect obtained from dose-response modelling of animal experiments.For tumours in male rats, a BMD of 30 mg kg(-1) body weight per day and a "BMD lower confidence limit" (BMDL) of 23 mg kg(-1) d(-1) were calculated from available long-term animal experiments. The average human exposure to formaldehyde from alcoholic beverages was estimated at 8·10(-5) mg kg(-1) d(-1). Comparing the human exposure with BMDL, the resulting MOE was above 200,000 for average scenarios. Even in the worst-case scenarios, the MOE was never below 10,000, which is considered to be the threshold for public health concerns.The risk assessment shows that the cancer risk from formaldehyde to the alcohol-consuming population is negligible and the priority for risk management (e.g. to reduce the contamination) is very low. The major risk in alcoholic beverages derives from ethanol and acetaldehyde.

Migration of formaldehyde from melamine-ware: UK 2008 survey results.

Science.gov (United States)

Potter, E L J; Bradley, E L; Davies, C R; Barnes, K A; Castle, L

2010-06-01

Fifty melamine-ware articles were tested for the migration of formaldehyde - with hexamethylenetetramine (HMTA) expressed as formaldehyde - to see whether the total specific migration limit (SML(T)) was being observed. The SML(T), given in European Commission Directive 2002/72/EC as amended, is 15 mg kg(-1). Fourier transform-infrared (FT-IR) spectroscopy was carried out on the articles to confirm the plastic type. Articles were exposed to the food simulant 3% (w/v) aqueous acetic acid under conditions representing their worst foreseeable use. Formaldehyde and HMTA in food simulants were determined by a spectrophotometric derivatization procedure. Positive samples were confirmed by a second spectrophotometric procedure using an alternative derivatization agent. As all products purchased were intended for repeat use, three sequential exposures to the simulant were carried out. Formaldehyde was detected in the simulant exposed to 43 samples. Most of the levels found were well below the limits set in law such that 84% of the samples tested were compliant. However, eight samples had formaldehyde levels that were clearly above the legal maximum at six to 65 times the SML(T).

Performance of optical biosensor using alcohol oxidase enzyme for formaldehyde detection

Science.gov (United States)

Sari, A. P.; Rachim, A.; Nurlely, Fauzia, V.

2017-07-01

The recent issue in the world is the long exposure of formaldehyde which is can increase the risk of human health, therefore, that is very important to develop a device and method that can be optimized to detect the formaldehyde elements accurately, have a long lifetime and can be fabricated and produced in large quantities. A new and simple prepared optical biosensor for detection of formaldehyde in aqueous solutions using alcohol oxidase (AOX) enzyme was successfully fabricated. The poly-n-butyl acrylic-co-N-acryloxysuccinimide (nBA-NAS) membranes containing chromoionophore ETH5294 were used for immobilization of alcohol oxidase enzyme (AOX). Biosensor response was based on the colour change of chromoionophore as a result of enzymatic oxidation of formaldehyde and correlated with the detection concentration of formaldehyde. The performance of biosensor parameters were measured through the optical absorption value using UV-Vis spectrophotometer including the repeatability, reproducibility, selectivity and lifetime. The results showed that the prepared biosensor has good repeatability (RSD = 1.9 %) and good reproducibility (RSD = 2.1 %). The biosensor was selective formaldehyde with no disturbance by methanol, ethanol, and acetaldehyde, and also stable before 49 days and decrease by 41.77 % after 49 days.

Snow and ice perturbation during historical volcanic eruptions and the formation of lahars and floods

Science.gov (United States)

Major, Jon J.; Newhall, Christopher G.

1989-10-01

Historical eruptions have produced lahars and floods by perturbing snow and ice at more than 40 volcanoes worldwide. Most of these volcanoes are located at latitudes higher than 35°; those at lower latitudes reach altitudes generally above 4000 m. Volcanic events can perturb mantles of snow and ice in at least five ways: (1) scouring and melting by flowing pyroclastic debris or blasts of hot gases and pyroclastic debris, (2) surficial melting by lava flows, (3) basal melting of glacial ice or snow by subglacial eruptions or geothermal activity, (4) ejection of water by eruptions through a crater lake, and (5) deposition of tephra fall. Historical records of volcanic eruptions at snow-clad volcanoes show the following: (1) Flowing pyroclastic debris (pyroclastic flows and surges) and blasts of hot gases and pyroclastic debris are the most common volcanic events that generate lahars and floods; (2) Surficial lava flows generally cannot melt snow and ice rapidly enough to form large lahars or floods; (3) Heating the base of a glacier or snowpack by subglacial eruptions or by geothermal activity can induce basal melting that may result in ponding of water and lead to sudden outpourings of water or sediment-rich debris flows; (4) Tephra falls usually alter ablation rates of snow and ice but generally produce little meltwater that results in the formation of lahars and floods; (5) Lahars and floods generated by flowing pyroclastic debris, blasts of hot gases and pyroclastic debris, or basal melting of snow and ice commonly have volumes that exceed 105 m3. The glowing lava (pyroclastic flow) which flowed with force over ravines and ridges...gathered in the basin quickly and then forced downwards. As a result, tremendously wide and deep pathways in the ice and snow were made and produced great streams of water (Wolf 1878).

A Formaldehyde Exposure Assessment Tool for Occupants of FEMA Temporary Housing Units

Energy Technology Data Exchange (ETDEWEB)

Parthasarathy, Srinandini; Spears, Michael; Maddalena, Randy L.; Russell, Marion L; Apte, Michael G.

2010-10-01

The report outlines the methodology used to develop a web-based tool to assess the formaldehyde exposure of the occupants of Federal Emergency Management Administration (FEMA) temporary housing units (THUs) after Hurricanes Katrina and Rita in 2005. Linear regression models were built using available data to retrospectively estimate the indoor temperature and relative humidity, formaldehyde emission factors and concentration, and hence the formaldehyde exposures. The interactive web-tool allows the user to define the inputs to the model to evaluate formaldehyde exposures for different scenarios.

Boundary layer new particle formation over East Antarctic sea ice – possible Hg-driven nucleation?

Directory of Open Access Journals (Sweden)

R. S. Humphries

2015-12-01

Full Text Available Aerosol observations above the Southern Ocean and Antarctic sea ice are scarce. Measurements of aerosols and atmospheric composition were made in East Antarctic pack ice on board the Australian icebreaker Aurora Australis during the spring of 2012. One particle formation event was observed during the 32 days of observations. This event occurred on the only day to exhibit extended periods of global irradiance in excess of 600 W m−2. Within the single air mass influencing the measurements, number concentrations of particles larger than 3 nm (CN3 reached almost 7700 cm−3 within a few hours of clouds clearing, and grew at rates of 5.6 nm h−1. Formation rates of 3 nm particles were in the range of those measured at other Antarctic locations at 0.2–1.1 ± 0.1 cm−3 s−1. Our investigations into the nucleation chemistry found that there were insufficient precursor concentrations for known halogen or organic chemistry to explain the nucleation event. Modelling studies utilising known sulfuric acid nucleation schemes could not simultaneously reproduce both particle formation or growth rates. Surprising correlations with total gaseous mercury (TGM were found that, together with other data, suggest a mercury-driven photochemical nucleation mechanism may be responsible for aerosol nucleation. Given the very low vapour pressures of the mercury species involved, this nucleation chemistry is likely only possible where pre-existing aerosol concentrations are low and both TGM concentrations and solar radiation levels are relatively high (∼ 1.5 ng m−3 and ≥ 600 W m−2, respectively, such as those observed in the Antarctic sea ice boundary layer in this study or in the global free troposphere, particularly in the Northern Hemisphere.

Formation of Amino Acid Precursors by Bombardment of Interstellar Ice Analogs with High Energy Heavy Ions

Science.gov (United States)

Kobayashi, Kensei; Mita, Hajime; Yoshida, Satoshi; Shibata, Hiromi; Enomoto, Shingo; Matsuda, Tomoyuki; Fukuda, Hitoshi; Kondo, Kotaro; Oguri, Yoshiyuki; Kebukawa, Yoko

2016-07-01

A wide variety of organic compounds have been detected in extraterrestrial bodies. It has been recognized that carbonaceous chondrites contain pristine amino acids [1]. There are several scenarios of the formation of such extraterrestrial amino acids or their precursors. Greenberg proposed a scenario that complex organic compounds were formed in interstellar ices in dense clouds, which were brought into solar system small bodies when the solar system was formed [2]. The ice mantles of interstellar dust particles (ISDs) in dense clouds are composed of H2O, CO, CH3OH, CH4, CO2, NH3, etc. In order to verify the scenario, a number of laboratory experiments have been conducted where interstellar ice analogs were irradiated with high-energy particles [3,4] or UV [5,6], and formation of complex organic compounds including amino acid precursors were detected in the products. Though ion-molecular reactions in gaseous phase and surface reactions on the ice mantles have been studied intensively, much less works on cosmic rays-induced reaction have been reported. In order to study possible formation of complex molecules in interstellar ices, frozen mixtures of water, methanol and ammonia with various mixing ratios were irradiated with high-energy heavy ions such as carbon ions (290 MeV/u) and neon ions (400 MeV/u) from HIMAC, NIRS, Japan. For comparison, gaseous mixtures of water, ammonia, carbon monoxide, carbon dioxide, and/or methane were irradiated with protons (2.5 MeV) from a Tandem accelerator, Tokyo Tech, Japan. Amino acids in the products were determined by cation exchange HPLC after acid hydrolysis. Products, both before and after acid hydrolysis, were also characterized by FT-IR and other techniques. Amino acids were detected in the hydrolyzed products after mixture of CH3OH, NH3 and H2O with various mixing ratios were irradiated with heavy ions, including when their mixing ratio was set close to the reported value of the interstellar ices (10:1:37). In the HIMAC

Concentrations of formaldehyde in rain waters harvested at the ...

African Journals Online (AJOL)

Formaldehyde has been recognized as one of the most important pollutants and a carcinogen that is present in the air, water, foods, soils, fabrics, cosmetics, cigarette smoke and treated wood. Related health effects and hazards are linked to formaldehyde, depending on mode of exposure which includes: weakness, ...

Isotope effects and their implications for the covalent binding of inhaled [3H]- and [14C]formaldehyde in the rat nasal mucosa

International Nuclear Information System (INIS)

Heck Hd'; Casanova, M.

1987-01-01

DNA-protein crosslinks were formed in the nasal respiratory mucosa of Fischer-344 rats exposed for 3 hr to selected concentrations of [ 3 H]- and [ 14 C]formaldehyde ( 3 HCHO and H 14 CHO). In rats depleted of glutathione (GSH) and exposed to 10 ppm of 3 HCHO and H 14 CHO, the 3 H/ 14 C ratio of the fraction of the DNA that was crosslinked to proteins was significantly (39 +/- 6%) higher than that of the inhaled gas. This suggests an isotope effect, either on the formation of DNA-protein crosslinks by labeled HCHO or on the oxidation of labeled HCHO catalyzed by formaldehyde (FDH) or aldehyde dehydrogenase (AldDH). The possibility of an isotope effect on the formation of crosslinks was investigated using rat hepatic nuclei incubated with [ 3 H]- and [ 14 C]formaldehyde (0.1 mM, 37 degrees C). A small (3.4 +/- 0.9%) isotope effect was detected on this reaction, which slightly favored 3 HCHO over H 14 CHO in binding to DNA. The magnitude of this isotope effect cannot account for the high isotope ratio observed in the crosslinked DNA in vivo. The possibility of an isotope effect on the oxidation of 3 HCHO and H 14 CHO catalyzed by FDH was investigated using homogenates of the rat nasal mucosa incubated with [ 3 H]- and [ 14 C]formaldehyde at total formaldehyde concentrations ranging from 0.1 to 11 microM, NAD+ (1 mM), GSH (15 mM), and pyrazole (1 mM). The experiments showed that 3 HCHO is oxidized significantly more slowly than H 14 CHO under these conditions (Vmax/Km (H 14 CHO) divided by Vmax/Km ( 3 HCHO) = 1.82 +/- 0.11). A similar isotope effect was observed in the absence of GSH, presumably due to the oxidation of 3 HCHO and H 14 CHO catalyzed by AldDH

Characterization and Application of Urea-Formaldehyde-Furfural Co-condensed Resins as Wood Adhesives

Directory of Open Access Journals (Sweden)

Jizhi Zhang

2014-08-01

Full Text Available Furfural, as an organic compound derived from biomass materials, was used to partially substitute for formaldehyde in the synthesis of UF resin. Urea-formaldehyde-furfural co-condensed (UFFR resins with different substitute ratios of furfural to formaldehyde (FR/F were prepared. The effects of the FR/F substitute ratio on the performances of UFFR resins were investigated. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS and Fourier transform infrared spectroscopy (FT-IR were applied to characterize the chemical structures of UFFR resins. Plywood bonded by these resins was manufactured, and its bond strength and formaldehyde emission were measured. The results showed that the substitution of furfural in place of formaldehyde could reduce the free formaldehyde content effectively at the expense of prolongation of the curing time. The spectra of MALDI-TOF and FTIR confirmed the co-condensation of urea-formaldehyde-furfural both in uncured and cured resins. Plywood prepared under optimized parameters could yield high bond strength and low formaldehyde emission, which were 0.84 MPa and 0.23 ppm, respectively. The optimized parameters were as follows: a FR/F substitute ratio of 1/3; 1% (NH42S2O8 as the curing agent; and a hot pressing temperature of 130 °C. Hence, it is feasible to substitute partially formaldehyde by furfural to prepare UFFR resins as wood adhesives for plywood.

On the role of ice-nucleating aerosol in the formation of ice particles in tropical mesoscale convective systems

Science.gov (United States)

Ladino, Luis A.; Korolev, Alexei; Heckman, Ivan; Wolde, Mengistu; Fridlind, Ann M.; Ackerman, Andrew S.

2018-01-01

Over decades, the cloud physics community has debated the nature and role of aerosol particles in ice initiation. The present study shows that the measured concentration of ice crystals in tropical mesoscale convective systems exceeds the concentration of ice nucleating particles (INPs) by several orders of magnitude. The concentration of INPs was assessed from the measured aerosol particles concentration in the size range of 0.5 to 1 µm. The observations from this study suggest that primary ice crystals formed on INPs make only a minor contribution to the total concentration of ice crystals in tropical mesoscale convective systems. This is found by comparing the predicted INP number concentrations with in-situ ice particle number concentrations. The obtained measurements suggest that ice multiplication is the likely explanation for the observed high concentrations of ice crystals in this type of convective system. PMID:29551842

Genotoxicity of formaldehyde: Molecular basis of DNA damage and mutation

Directory of Open Access Journals (Sweden)

Masanobu eKawanishi

2014-09-01

Full Text Available Formaldehyde is commonly used in the chemical industry and is present in the environment, such as vehicle emissions, some building materials, food and tobacco smoke. It also occurs as a natural product in most organisms, the sources of which include a number of metabolic processes. It causes various acute and chronic adverse effects in humans if they inhale its fumes. Among the chronic effects on human health, we summarize data on genotoxicity and carcinogenicity in this review, and we particularly focus on the molecular mechanisms involved in the formaldehyde mutagenesis. Formaldehyde mainly induces N-hydroxymethyl mono-adducts on guanine, adenine and cytosine, and N-methylene crosslinks between adjacent purines in DNA. These crosslinks are types of DNA damage potentially fatal for cell survival if they are not removed by the nucleotide excision repair pathway. In the previous studies, we showed evidence that formaldehyde causes intra-strand crosslinks between purines in DNA using a unique method (Matsuda et al. Nucleic Acids Res. 26, 1769-1774,1998. Using shuttle vector plasmids, we also showed that formaldehyde as well as acetaldehyde induces tandem base substitutions, mainly at 5’-GG and 5’-GA sequences, which would arise from the intra-strand crosslinks. These mutation features are different from those of other aldehydes such as crotonaldehyde, acrolein, glyoxal and methylglyoxal. These findings provide molecular clues to improve our understanding of the genotoxicity and carcinogenicity of formaldehyde.

One-pot synthesis of biocompatible Te-phenol formaldehyde resin core-shell nanowires with uniform size and unique fluorescent properties by a synergized soft-hard template process

International Nuclear Information System (INIS)

Qian Haisheng; Zhu Enbo; Zheng Shunji; Yang Xingyun; Li Liangchao; Tong Guoxiu; Li Zhengquan; Hu Yong; Guo Changfa; Guo Huichen

2010-01-01

One-pot hydrothermal process has been developed to synthesize uniform Te-phenol formaldehyde resin core-shell nanowires with unique fluorescent properties. A synergistic soft-hard template mechanism has been proposed to explain the formation of the core-shell nanowires. The Te-phenol formaldehyde resin core-shell nanowires display unique fluorescent properties, which give strong luminescent emission in the blue-violet and green regions with excitation wavelengths of 270 nm and 402 nm, respectively.

One-pot synthesis of biocompatible Te@phenol formaldehyde resin core-shell nanowires with uniform size and unique fluorescent properties by a synergized soft-hard template process.

Science.gov (United States)

Qian, Haisheng; Zhu, Enbo; Zheng, Shunji; Li, Zhengquan; Hu, Yong; Guo, Changfa; Yang, Xingyun; Li, Liangchao; Tong, Guoxiu; Guo, Huichen

2010-12-10

One-pot hydrothermal process has been developed to synthesize uniform Te@phenol formaldehyde resin core-shell nanowires with unique fluorescent properties. A synergistic soft-hard template mechanism has been proposed to explain the formation of the core-shell nanowires. The Te@phenol formaldehyde resin core-shell nanowires display unique fluorescent properties, which give strong luminescent emission in the blue-violet and green regions with excitation wavelengths of 270 nm and 402 nm, respectively.

One-pot synthesis of biocompatible Te-phenol formaldehyde resin core-shell nanowires with uniform size and unique fluorescent properties by a synergized soft-hard template process

Energy Technology Data Exchange (ETDEWEB)

Qian Haisheng; Zhu Enbo; Zheng Shunji; Yang Xingyun; Li Liangchao; Tong Guoxiu [Department of Chemistry, College of Chemistry and Life Science, Zhejiang Normal University, Jinhua 321004 (China); Li Zhengquan; Hu Yong; Guo Changfa [Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004 (China); Guo Huichen, E-mail: shqian@zjnu.cn, E-mail: ghch-2004@hotmail.com [State Key Laboratory of Veterinary Etiological Biology and Key Laboratory of Animal Virology of Ministry of Agriculture, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping 11, Lanzhou, Gansu 730046 (China)

2010-12-10

One-pot hydrothermal process has been developed to synthesize uniform Te-phenol formaldehyde resin core-shell nanowires with unique fluorescent properties. A synergistic soft-hard template mechanism has been proposed to explain the formation of the core-shell nanowires. The Te-phenol formaldehyde resin core-shell nanowires display unique fluorescent properties, which give strong luminescent emission in the blue-violet and green regions with excitation wavelengths of 270 nm and 402 nm, respectively.

ISOFORMAL: isotopic tracing of formaldehyde sources in housing. Intermediary report

International Nuclear Information System (INIS)

2011-01-01

The authors report an investigation which comprised a sampling and a chemical and isotopic analysis of emissions from the main indoor formaldehyde pollution sources in order to create a exhaustive database. Emissions which are characteristic of motorcar traffic, are also sampled in order to asses their possible contribution in the housing air. This step will be used to develop emission simulations of formaldehyde sources in a laboratory-house in order to validate the isotopic approach as tracing tool for sources of this compound. The report describes the carbon and hydrogen steady isotopes. It presents the sampling procedure, reports the determination of formaldehyde concentrations by high performance liquid chromatography with UV detectors, the use of gas source mass spectrometry, and the analytic development of the isotopic analysis of formaldehyde by gas chromatography combustion isotope ratio mass spectrometry. Outdoor and indoor pollution sources are discussed

Investigation of the detoxification mechanism of formaldehyde-treated tetanus toxin

DEFF Research Database (Denmark)

Thaysen-Andersen, Morten; Jørgensen, Sys Borcher; Wilhelmsen, Ellen Sloth

2007-01-01

and properties of the vaccine component, occurs through partly unknown chemical modifications of the toxin. The aim of this study was to gain knowledge of the detoxification mechanism in the generation of the tetanus vaccine. Two approaches were chosen: (i) the effect of changes in the concentrations of lysine...... The tetanus vaccine is based on the extremely potent tetanus neurotoxin (TeNT), which is converted by treatment with formaldehyde and lysine into the non-toxic, but still immunogenic tetanus toxoid (TTd). This formaldehyde-induced detoxification, which to a large extend determines the quality...... and formaldehyde in the detoxification process and (ii) characterisation of the chemically detoxified TTd. (i) We examined a number of TTd components that was produced by varying the concentrations of formaldehyde and lysine during the inactivation. Toxicity tests showed that the detoxification failed when...

The Effectors and Sensory Sites of Formaldehyde-responsive Regulator FrmR and Metal-sensing Variant *

Science.gov (United States)

Osman, Deenah; Piergentili, Cecilia; Chen, Junjun; Sayer, Lucy N.; Usón, Isabel; Huggins, Thomas G.; Robinson, Nigel J.; Pohl, Ehmke

2016-01-01

The DUF156 family of DNA-binding transcriptional regulators includes metal sensors that respond to cobalt and/or nickel (RcnR, InrS) or copper (CsoR) plus CstR, which responds to persulfide, and formaldehyde-responsive FrmR. Unexpectedly, the allosteric mechanism of FrmR from Salmonella enterica serovar Typhimurium is triggered by metals in vitro, and variant FrmRE64H gains responsiveness to Zn(II) and cobalt in vivo. Here we establish that the allosteric mechanism of FrmR is triggered directly by formaldehyde in vitro. Sensitivity to formaldehyde requires a cysteine (Cys35 in FrmR) conserved in all DUF156 proteins. A crystal structure of metal- and formaldehyde-sensing FrmRE64H reveals that an FrmR-specific amino-terminal Pro2 is proximal to Cys35, and these residues form the deduced formaldehyde-sensing site. Evidence is presented that implies that residues spatially close to the conserved cysteine tune the sensitivities of DUF156 proteins above or below critical thresholds for different effectors, generating the semblance of specificity within cells. Relative to FrmR, RcnR is less responsive to formaldehyde in vitro, and RcnR does not sense formaldehyde in vivo, but reciprocal mutations FrmRP2S and RcnRS2P, respectively, impair and enhance formaldehyde reactivity in vitro. Formaldehyde detoxification by FrmA requires S-(hydroxymethyl)glutathione, yet glutathione inhibits formaldehyde detection by FrmR in vivo and in vitro. Quantifying the number of FrmR molecules per cell and modeling formaldehyde modification as a function of [formaldehyde] demonstrates that FrmR reactivity is optimized such that FrmR is modified and frmRA is derepressed at lower [formaldehyde] than required to generate S-(hydroxymethyl)glutathione. Expression of FrmA is thereby coordinated with the accumulation of its substrate. PMID:27474740

Supramolecular nano-sniffers for ultrasensitive detection of formaldehyde.

Science.gov (United States)

Akshath, Uchangi Satyaprasad; Bhatt, Praveena

2018-02-15

Supramolecular nanoparticle hybrids for biosensing of analytes have been a major focus due to their tunable optical and surface properties. Quantum dots-Gold nanoparticle (QDs-GNP) based FRET probes involving turn on/off principles have gained immense interest due to their specificity and sensitivity. Recent focus is on applying these supramolecular hybrids for enzyme operated biosensors that can specifically turn-on fluorescence induced by co-factor or product formed from enzymatic reaction. The present study focuses on locking and unlocking the interaction between QD-GNP pair leading to differential fluorescent properties. Cationic GNPs efficiently quenched the anionic QD fluorescence by forming nanoparticle hybrid. Quenching interaction between QD-GNP pair was unlocked by NADH leading to QD fluorescence turn-on. This phenomenon was applied for the successful detection of formaldehyde using NAD + dependent formaldehyde dehydrogenase. The proposed nano-sniffer could successfully detect formaldehyde from 0.001 to 100000ng/mL (R 2 = 0.9339) by the turn off-turn on principle. It could also detect formaldehyde in fruit juice and wine samples indicating its stability and sensitivity in real samples. The proposed nanoprobe can have wide applications in developing enzyme biosensors in future. Copyright © 2017 Elsevier B.V. All rights reserved.

Melamine-bridged alkyl resorcinol modified urea - formaldehyde resin for bonding hardwood plywood

Science.gov (United States)

Chung-Yun Hse; Mitsuo Higuchi

2010-01-01

A powdery product was obtained by the reaction of methylolated melamine with alkyl resorcinols to form melamine-bridged alkyl resorcinols (MARs). The effects of the addition of this powder on the bonding strength and formaldehyde emission of urea–formaldehyde (UF) resins were investigated. Three types of UF resins with a formaldehyde/urea molar ratio of 1.3 synthesized...

Urea-formaldehyde resins: production, application, and testing

Science.gov (United States)

Nuryawan, A.; Risnasari, I.; Sucipto, T.; Heri Iswanto, A.; Rosmala Dewi, R.

2017-07-01

Urea-formaldehyde (UF) resin, one of the most important formaldehyde resin adhesives, is a polymeric condensation product of formaldehyde with urea, and being widely used for the manufacture of wood-based composite panels, such as plywood, particleboard, and fiberboard. In spite of its benefits such as fast curing, good performance in the panels (colorless), and lower cost; formaldehyde emission (FE) originated from either UF resin itself or composite products bonded by UF resins is considered a critical drawback as it affects human health particularly in indoor environment. In order to reduce the FE, lowering formaldehyde/urea (F/U) mole ratio in the synthesis of the UF resin was done. In this study, synthesis of UF resins was carried out following the conventional alkaline-acid two-step reaction with a second addition of urea, resulting in F/U mole ratio around 1.0, namely 0.95; 1.05, and 1.15. The UF resins produced were used as binder for particleboard making. The board was manufactured in the laboratory using shaving type particle of Gmelina wood, 8% UF resin based on oven dry particle, and 1% NH4Cl (20%wt) as hardener for the resin. The target of the thickness was 10 mm and the dimension was 25 cm x 25 cm. The resulted particleboard then was evaluated the physical and the mechanical properties by Japanese Industrial Standard (JIS) A 5908 (2003). Further, the resulted particleboard also was used for the mice cage’s wall in order to mimic the real living environment. After four weeks exposure in the cages, the mice then were evaluated their mucous organs as well as their blood. The experiment results were as follows: 1) It was possible to synthesis UF resins with low F/U mole ratio; 2) However, the particleboard bonded UF resins with low F/U mole ratio showed poor properties, particularly on the thickness swelling and modulus of elasticity; 3) There was no significant differences among the mucous organs of the mice after a month exposure FE originated from

Aerodynamic Performance Degradation Induced by Ice Accretion. PIV Technique Assessment in Icing Wind Tunnel

Science.gov (United States)

Gregorio, Fabrizio De

The aim of the present chapter is to consider the use of PIV technique in an industrial icing wind tunnel (IWT) and the potentiality/advantages of applying the PIV technique to this specific field. The purpose of icing wind tunnels is to simulate the aircraft flight condition through cloud formations. In this operational condition ice accretions appear on the aircraft exposed surfaces due to the impact of the water droplets present in the clouds and the subsequent solidification. The investigation of aircraft aerodynamic performances and flight safety in icing condition is a fundamental aspect in the phase of design, development and certification of new aircrafts. The description of this unusual ground testing facility is reported. The assessment of PIV in CIRA-IWT has been investigated. Several technological problems have been afforded and solved by developing the components of the measurement system, such as the laser system and the recording apparatus, both fully remotely controlled, equipped with several traversing mechanism and protected by the adverse environment conditions (temperature and pressure). The adopted solutions are described. Furthermore, a complete test campaign on a full-scale aircraft wing tip, equipped with moving slat and deicing system has been carried out by PIV. Two regions have been investigated. The wing leading-edge (LE) area has been studied with and without ice accretion and for different cloud characteristics. The second activitiy was aimed at the investigation of the wing-wake behavior. The measurements were aimed to characterize the wake for the model in cruise condition without ice formation and during the ice formation.

Research of radiation firmness of transparent melamine-formaldehyde polymers

International Nuclear Information System (INIS)

Lebedev, V.V.

2007-01-01

Radiation properties of the transparent melamine-formaldehyde polymers offered in quality polymeric basis for making of plastic scintillators are explored in this work. Plastic scintillator is composition, that consists of polymer (polymeric basis) and organic fluorescent addition. Scintillation efficiency and light output are basic properties of plastic scintillators. Firmness to influencing of ionizing radiation is important property of scintillators. From all types of scintillators the plastic are most radiation-proof. Cured melamine-formaldehyde resin and melamine-formaldehyde resin modified by different polyol modifiers was a research object. It is shown that radiation firmness for given types of polymeric material considerably depends on composition of polymer and from technology and temperature condition of its receipt. By the method IR-spectroscopy the structural changes in melamine-formaldehyde polymers under action of irradiation were explored. The maximal falling after the irradiation was marked in intensity of luminescence, which went down to 50% from an initial level. Like the coefficients of admission for all compositions got worse of a to 30-35% level from initial one. Mechanical properties went down on 20-30%. The radiation loss of mass made less than 1% for all polymers. With the increase of temperature of curing firmness rises. Thus, on the basis of the conducted researches radiation firmness for different melamine-formaldehyde polymers is determined and processes what is going on in material under action of radiation are studied. The limited doses of irradiation for each of explored polymers are determined. (authors)

Absorption of formaldehyde in water

NARCIS (Netherlands)

Winkelman, Jozef Gerhardus Maria

2003-01-01

Deze dissertatie beschrijft theoretisch en experimenteel werk aan de absorptie van formaldehyde in water. Met resultaten hiervan zijn chemisch-technische modellen ontwikkeld voor de beschrijving en optimalisatie van industriële formaldehydeabsorbeurs. Deze samenvatting geeft eerst algemene

Biochemical gas sensor (bio-sniffer) for ultrahigh-sensitive gaseous formaldehyde monitoring.

Science.gov (United States)

Kudo, Hiroyuki; Suzuki, Yuki; Gessei, Tomoko; Takahashi, Daishi; Arakawa, Takahiro; Mitsubayashi, Kohji

2010-10-15

An ultrahigh-sensitive fiber-optic biochemical gas sensor (bio-sniffer) for continuous monitoring of indoor formaldehyde was constructed and tested. The bio-sniffer measures gaseous formaldehyde as fluorescence of nicotinamide adenine dinucleotide (NADH), which is the product of formaldehyde dehydrogenase (FALDH) reaction. The bio-sniffer device was constructed by attaching a flow cell with a FALDH immobilized membrane onto a fiber-optic NADH measurement system. The NADH measurement system utilizes an ultraviolet-light emitting diode (UV-LED) with peak emission of 335 nm as an excitation light source. The excitation light was introduced to an optical fiber probe, and fluorescence emission of neighboring NADH, which was produced by applying formaldehyde vapor to the FALDH membrane, was concentrically measured with a photomultiplier tube. Assessment of the bio-sniffer was carried out using a standard gas generator. Response, calibration range and selectivity to other chemical substances were investigated. Circulating phosphate buffer, which contained NAD+, available for continuous monitoring of formaldehyde vapor. The calibration range of the bio-sniffer was 2.5 ppb to 10 ppm, which covers the guideline value of the World Health Organization (80 ppb). High selectivity to other gaseous substances due to specific activity of FALDH was also confirmed. Considering its high sensitivity, a possible application of the bio-sniffer is continuous indoor formaldehyde monitoring to provide healthy residential atmosphere. Copyright © 2010 Elsevier B.V. All rights reserved.

Bacterial Ice Crystal Controlling Proteins

Science.gov (United States)

Lorv, Janet S. H.; Rose, David R.; Glick, Bernard R.

2014-01-01

Across the world, many ice active bacteria utilize ice crystal controlling proteins for aid in freezing tolerance at subzero temperatures. Ice crystal controlling proteins include both antifreeze and ice nucleation proteins. Antifreeze proteins minimize freezing damage by inhibiting growth of large ice crystals, while ice nucleation proteins induce formation of embryonic ice crystals. Although both protein classes have differing functions, these proteins use the same ice binding mechanisms. Rather than direct binding, it is probable that these protein classes create an ice surface prior to ice crystal surface adsorption. Function is differentiated by molecular size of the protein. This paper reviews the similar and different aspects of bacterial antifreeze and ice nucleation proteins, the role of these proteins in freezing tolerance, prevalence of these proteins in psychrophiles, and current mechanisms of protein-ice interactions. PMID:24579057

A novel reaction catalysed by active carbons production of dichloromethane from phosgene and formaldehyde

Energy Technology Data Exchange (ETDEWEB)

Ryan, T A; Stacey, M H

1984-08-01

A variety of Activated charcoals have been found to catalyse a reaction between phosgene and formaldehyde. In a continuous flow fluidized bed reactor, the reaction rate reaches a broad maximum near 170/sup 0/C where the selectivity is consistent with the stoichiometry. The reaction proceeds via a strongly adsorbed intermediate which has been identified as chloromethyl chloroformate. This ester is an adduct of formaldehyde and phosgen and forms rapidly above 100/sup 0/C in co-adsorption/desorption experiments. It decomposes rapidly 170/sup 0/C without significant desorption of the intact molecule to give the observed products dichloromethane and carbon dioxide. Under steady-state conditions the rate-determining step is the formation of this ester so that it is normally only present on the surface at low coverages; hence it is not observable in the gas phase. The catalysis is probably due to the presence of polar acid or base sites on the surface of the activated charcoals.

Formation of amino acid precursors in the Solar System small bodies using Aluminium-26 as an energy source

Science.gov (United States)

Kebukawa, Yoko; Kobayashi, Kensei; Kawai, Jun; Mita, Hajime; Tachibana, Shogo; Yoda, Isao; Misawa, Shusuke

2016-07-01

Carbonaceous chondrites contain various organic matter including amino acids that may have played an important role for origin of life on the early Earth. The parent bodies of the chondritic meteorites likely formed from silicate dust grains containing some water ice and organic compounds. These planetesimals are known to contain short-lived radio isotopes such as ^{26}Al, and the heat generated from the decay of ^{26}Al was considered to be used for melting ice. The liquid water, for example, changed anhydrous silicates into hydrous silicates, i.e., aqueous alteration. The liquid water would act also as an ideal reaction medium for various organic chemistry. Cody et al. [1] proposed IOM formation via formose reaction starting with formaldehyde and glycolaldehyde during aqueous activity in the small bodies. Additional hydrothermal experiments showed that ammonia enhanced the yields of IOM like organic solids [2]. Formaldehyde and ammonia are ubiquitous in the Solar System and beyond, e.g., comets contain H _{2}CO : NH _{3} : H _{2}O = 0.4-4 : 0.5-1.5 : 100 [3]. Thus these molecules can be expected to have existed in some Solar System small bodies. We study the liquid phase chemistry of the formaldehyde and ammonia, including formations of amino acid precursor molecules, via hydrothermal experiments at isothermal temperatures of 90 °C to 200 °C. We also evaluate the effects of gamma-ray which is released from the decay of ^{26}Al with gamma-ray irradiation experiments using a ^{60}Co gamma-ray source at Tokyo Institute of Technology. Amino acids were detected mostly after acid hydrolysis of heated or irradiated solutions, indicating that most of the amino acids in the products exist as precursors. Some samples contained 'free' amino acids that were detected without acid hydrolysis, but much lower abundance than after acid hydrolysis. Kendrick mass defect (KMD) analyses of High resolution mass spectra obtained using ESI-MS revealed that various CHO and CHNO

INFRARED SPECTROSCOPIC SURVEY OF THE QUIESCENT MEDIUM OF NEARBY CLOUDS. I. ICE FORMATION AND GRAIN GROWTH IN LUPUS

International Nuclear Information System (INIS)

Boogert, A. C. A.; Chiar, J. E.; Knez, C.; Mundy, L. G.; Öberg, K. I.; Pendleton, Y. J.; Tielens, A. G. G. M.; Van Dishoeck, E. F.

2013-01-01

Infrared photometry and spectroscopy (1-25 μm) of background stars reddened by the Lupus molecular cloud complex are used to determine the properties of grains and the composition of ices before they are incorporated into circumstellar envelopes and disks. H 2 O ices form at extinctions of A K = 0.25 ± 0.07 mag (A V = 2.1 ± 0.6). Such a low ice formation threshold is consistent with the absence of nearby hot stars. Overall, the Lupus clouds are in an early chemical phase. The abundance of H 2 O ice (2.3 ± 0.1 × 10 –5 relative to N H ) is typical for quiescent regions, but lower by a factor of three to four compared to dense envelopes of young stellar objects. The low solid CH 3 OH abundance ( 2 O) indicates a low gas phase H/CO ratio, which is consistent with the observed incomplete CO freeze out. Furthermore it is found that the grains in Lupus experienced growth by coagulation. The mid-infrared (>5 μm) continuum extinction relative to A K increases as a function of A K . Most Lupus lines of sight are well fitted with empirically derived extinction curves corresponding to R V ∼ 3.5 (A K = 0.71) and R V ∼ 5.0 (A K = 1.47). For lines of sight with A K > 1.0 mag, the τ 9.7 /A K ratio is a factor of two lower compared to the diffuse medium. Below 1.0 mag, values scatter between the dense and diffuse medium ratios. The absence of a gradual transition between diffuse and dense medium-type dust indicates that local conditions matter in the process that sets the τ 9.7 /A K ratio. This process is likely related to grain growth by coagulation, as traced by the A 7.4 /A K continuum extinction ratio, but not to ice mantle formation. Conversely, grains acquire ice mantles before the process of coagulation starts

Simultaneous measurements of formaldehyde and nitrous acid in dews and gas phase in the atmosphere of Santiago, Chile

Science.gov (United States)

Rubio, María A.; Lissi, Eduardo; Villena, Guillermo; Elshorbany, Y. F.; Kleffmann, Jörg; Kurtenbach, Ralf; Wiesen, Peter

2009-12-01

The amounts of formaldehyde and nitrous acid (HONO) in gas phase and dews of Santiago de Chile were simultaneously measured. Formaldehyde concentrations values in the liquid phase (dews) correlate fairly well with those in the gaseous phase and are even higher than those expected from gas-dew equilibrium. On the other hand, nitrite concentrations in dews were considerably smaller (ca. 15 times) than those expected from the gas-phase concentrations. This under-saturation is attributed to diffusion limitations due to the relatively large HONO solubility. In agreement with this, under-saturation increases with the rate of dew formation and the pH of the collected waters, factors that should increase the rate of gas to liquid HONO transfer required to reach equilibrium.

Formaldehyde Surface Distributions and Variability in the Mexico City Basin

Science.gov (United States)

Junkermann, W.; Mohr, C.; Steinbrecher, R.; Ruiz Suarez, L.

2007-05-01

Formaldehyde ambient air mole fractions were measured throughout the dry season in March at three different locations in the Mexico City basin. The continuously running instruments were operated at Tenago del Aire, a site located in the Chalco valley in the southern venting area of the basin, at the Intituto Mexicano del Petroleo (IMP) in the northern part of the city and about 30 km north of the city at the campus of the Universidad Tecnològica de Tecamac (UTTEC). The technique used is the Hantzsch technology with a time resolution of 2 minutes and a detection limit of 100 ppt. Daily maxima peaked at 35 ppb formaldehyde in the city and about 15 to 20 ppb at the other sites. During night formaldehyde levels dropped to about 5 ppb or less. It is evident that the observed spatial and temporal variability in near surface formaldehyde distributions is strongly affected by local and regional advection processes.

Astronomical Ice: The Effects of Treating Ice as a Porous Media on the Dynamics and Evolution of Extraterrestrial Ice-Ocean Environments

Science.gov (United States)

Buffo, J.; Schmidt, B. E.

2015-12-01

With the prevalence of water and ice rich environments in the solar system, and likely the universe, becoming more apparent, understanding the evolutionary dynamics and physical processes of such locales is of great importance. Piqued interest arises from the understanding that the persistence of all known life depends on the presence of liquid water. As in situ investigation is currently infeasible, accurate numerical modeling is the best technique to demystify these environments. We will discuss an evolving model of ice-ocean interaction aimed at realistically describing the behavior of the ice-ocean interface by treating basal ice as a porous media, and its possible implications on the formation of astrobiological niches. Treating ice as a porous media drastically affects the thermodynamic properties it exhibits. Thus inclusion of this phenomenon is critical in accurately representing the dynamics and evolution of all ice-ocean environments. This model utilizes equations that describe the dynamics of sea ice when it is treated as a porous media (Hunke et. al. 2011), coupled with a basal melt and accretion model (Holland and Jenkins 1999). Combined, these two models produce the most accurate description of the processes occurring at the base of terrestrial sea ice and ice shelves, capable of resolving variations within the ice due to environmental pressures. While these models were designed for application to terrestrial environments, the physics occurring at any ice-water interface is identical, and these models can be used to represent the evolution of a variety of icy astronomical bodies. As terrestrial ice shelves provide a close analog to planetary ice-ocean environments, we truth test the models validity against observations of ice shelves. We apply this model to the ice-ocean interface of the icy Galilean moon Europa. We include profiles of temperature, salinity, solid fraction, and Darcy velocity, as well as temporally and spatially varying melt and

Rapid formation of gas giants, ice giants and super-Earths

Energy Technology Data Exchange (ETDEWEB)

Boss, A P [DTM, Carnegie Institution of Washington, 5241 Broad Branch Road, NW, Washington, DC 20015 (United States)], E-mail: boss@dtm.ciw.edu

2008-08-15

Giant planets might have been formed by either of the two basic mechanisms, top-down (disk instability) or bottom-up (core accretion). The latter mechanism is the most generally accepted mechanism and it begins with the collisional accumulation of solid cores that may then accrete sufficient gas to become gas giants. The former mechanism is more heretical and begins with the gravitational instability of the protoplanetary disk gas, leading to the formation of self-gravitating protoplanets, within which the dust settles to form a solid core. The disk instability mechanism has been thought of primarily as a mechanism for the formation of gas giants, but if it occurs in a disk that is being photoevaporated by the ultraviolet radiation from nearby massive stars, then the outer gaseous protoplanets can be photoevaporated as well and stripped of their gaseous envelopes. The result would then be ice giants (cold super-Earths), such as the objects discovered recently by microlensing orbiting two presumed M dwarf stars. M dwarfs that form in regions of future high-mass star formation would be expected to produce cold super-Earths orbiting at distances of several astronomical units (AU) and beyond, while M dwarfs that form in regions of low-mass star formation would be expected to have gas giants at those distances. Given that most stars are born in the former rather than in the latter regions, M dwarfs should have significantly more super-Earths than gas giants on orbits of several AU or more.

Rapid formation of gas giants, ice giants and super-Earths

International Nuclear Information System (INIS)

Boss, A P

2008-01-01

Giant planets might have been formed by either of the two basic mechanisms, top-down (disk instability) or bottom-up (core accretion). The latter mechanism is the most generally accepted mechanism and it begins with the collisional accumulation of solid cores that may then accrete sufficient gas to become gas giants. The former mechanism is more heretical and begins with the gravitational instability of the protoplanetary disk gas, leading to the formation of self-gravitating protoplanets, within which the dust settles to form a solid core. The disk instability mechanism has been thought of primarily as a mechanism for the formation of gas giants, but if it occurs in a disk that is being photoevaporated by the ultraviolet radiation from nearby massive stars, then the outer gaseous protoplanets can be photoevaporated as well and stripped of their gaseous envelopes. The result would then be ice giants (cold super-Earths), such as the objects discovered recently by microlensing orbiting two presumed M dwarf stars. M dwarfs that form in regions of future high-mass star formation would be expected to produce cold super-Earths orbiting at distances of several astronomical units (AU) and beyond, while M dwarfs that form in regions of low-mass star formation would be expected to have gas giants at those distances. Given that most stars are born in the former rather than in the latter regions, M dwarfs should have significantly more super-Earths than gas giants on orbits of several AU or more

Discovery of a cyclic 6 + 6 hexamer of d-biotin and formaldehyde

DEFF Research Database (Denmark)

Lisbjerg, Micke; Jessen, Bo M.; Rasmussen, Brian

2014-01-01

The discovery of receptors using templated synthesis enables the selection of strong receptors from complex mixtures. In this contribution we describe a study of the condensation of d-biotin and formaldehyde in acidic water. We have discovered that halide anions template the formation of a single...... isomer of a 6 + 6 macrocycle. The macrocycle (biotin[6]uril) is water-soluble, chiral and binds halide anions (iodide, bromide and chloride) with selectivity for iodide in water, and it can be isolated on a gram scale in a one-pot reaction in 63% yield....

Viscosity of interfacial water regulates ice nucleation

International Nuclear Information System (INIS)

Li, Kaiyong; Chen, Jing; Zhang, Qiaolan; Zhang, Yifan; Xu, Shun; Zhou, Xin; Cui, Dapeng; Wang, Jianjun; Song, Yanlin

2014-01-01

Ice formation on solid surfaces is an important phenomenon in many fields, such as cloud formation and atmospheric icing, and a key factor for applications in preventing freezing. Here, we report temperature-dependent nucleation rates of ice for hydrophilic and hydrophobic surfaces. The results show that hydrophilic surface presents a lower ice nucleation rate. We develop a strategy to extract the thermodynamic parameters, J 0 and Γ, in the context of classical nucleation theory. From the extracted J 0 and Γ, we reveal the dominant role played by interfacial water. The results provide an insight into freezing mechanism on solid surfaces

Preparation and characterization of phloroglucinol-formaldehyde aerogel

International Nuclear Information System (INIS)

Huang Changgang; China Academy of Engineering Physics, Mianyang; Tang Yongjian; Wang Chaoyang; Yan Hongmei

2006-01-01

Phloroglucinol-formaldehyde (PF) aerogels and carbonized PF (CPF) aerogels were prepared from Phloroglucinol (P) and Formaldehyde (F) by sol-gel, solvent exchanging, supercritical drying and carbonization processes. The aerogel has a large specific surface area, continuous nano-network and porous structure. The density and mean porosity radius will enlarge after being carbonized, while the specific surface area will be influenced little. The micro-structure and density of aerogel are controlled by concentration of total reactants and catalyzer, respectively. Aerogels with different micro-structure and different density fit for ICF targets can be prepared by optimizing synthesis conditions. (authors)

Formation of formaldehyde in biogas-engines and methods for reducing these emissions by exhaust-gas after-treatment; Entstehung von Formaldehydemissionen in Biogasmotoren und deren Verminderung durch inner- und nachmotorische Massnahmen

Energy Technology Data Exchange (ETDEWEB)

Bauer, Markus; Wachtmeister, Georg; Prager, Maximilian [TU Muenchen (Germany). Lehrstuhl fuer Verbrennungskraftmaschinen

2011-07-01

Having found numerous biogas-(co)generation plants exceeding the formaldehyde emission limits given in German Technical Instructions on Air Quality Control (TA Luft), the mechanisms of in-engine formation of formaldehyde were investigated at the Institute of Internal Combustion Engines (LVK) of the Technische Universitaet Muenchen in collaboration with the German Forschungsvereinigung Verbrennungskraftmaschinen e.V (FVV, Research Association for Combustion Engines; research project No. 918). In these investigations the potential for reducing formaldehyde emissions with in-engine measures was found to be limited unless deteriorations in engine efficiency and nitric oxides' emissions are accepted. As a result, after- treatment of the exhaust gases is necessary, especially with respect to the tightening of the formaldehyde limits in January 2009. To get information about the yet unknown long-term behaviour of exhaust-gas after-treatment on biogas plants, a further project was launched. Within half a year emissions of formaldehyde and methane, the latter of them with regard to its global warming potential, were investigated at two biogas plants equipped with two different technologies of after-treatment. These investigations proved regenerative thermal oxidation (RTO) as well as catalytic oxidation (Oxi-Kat) capable for reducing the emissions of formaldehyde below valid limits, though further research has to be conducted to improve the durability of the Oxi-Kat as well as the performance of the RTO in non-steady-state operation, especially cold start. Emissions of methane were effectively reduced with the RTO whereas the Oxi-Kat, which in fact was optimized for reducing emissions of formaldehyde, only had a negligible effect on it. It is expected that further research on catalytic coatings will improve the Oxi-Kat's performance in methane-oxidation. This project was sponsored by the Federal Ministry for the Environment, Nature Conservation and Reactor Safety

Formaldehyde emissions from ULEF- and NAF-bonded commercial hardwood plywood as influenced by temperature and relative humidity

Science.gov (United States)

Charles R. Frihart; James M. Wescott; Michael J. Birkeland; Kyle M. Gonner

2010-01-01

It is well documented in the literature that temperature and humidity can influence formaldehyde emissions from composite panels that are produced using urea-formaldehyde (UF) adhesives. This work investigates the effect of temperature and humidity on newer, ultra-low emitting formaldehyde urea formaldehyde (ULEF-UF) and no-added formaldehyde (NAF) adhesives. A...

PRODUCTION OF HIGH DENSITY PARTICLEBOARD USING MELAMINE-UREA-FORMALDEHYDE RESIN

Directory of Open Access Journals (Sweden)

Setsuo Iwakiri

2005-12-01

Full Text Available This research was developed aiming to evaluate the effects of board density and melamine-urea-formaldehyde resin onthe properties of particleboard for semi-structural applications. The boards were manufactured with nominal density of 0.65 g/cm³and 0.90 g/cm³ using urea-formaldehyde resin as control and melamine-urea-formaldehyde. The results showed a better dimensionallystability and mechanical properties of the boards manufactured with higher density and MUF resin content. The fine furnish usedfor external layer of particleboard in the industrial process, could be used for high density homogeneous board to semi-strucuturaluses, such as flooring applications.

The Australian Work Exposures Study: Prevalence of Occupational Exposure to Formaldehyde.

Science.gov (United States)

Driscoll, Timothy R; Carey, Renee N; Peters, Susan; Glass, Deborah C; Benke, Geza; Reid, Alison; Fritschi, Lin

2016-01-01

The aims of this study were to produce a population-based estimate of the prevalence of work-related exposure to formaldehyde, to identify the main circumstances of exposure and to describe the use of workplace control measures designed to decrease those exposures. The analysis used data from the Australian Workplace Exposures Study, a nationwide telephone survey, which investigated the current prevalence and exposure circumstances of work-related exposure to 38 known or suspected carcinogens, including formaldehyde, among Australian workers aged 18-65 years. Using the web-based tool OccIDEAS, semi-quantitative information was collected about exposures in the current job held by the respondent. Questions were addressed primarily at tasks undertaken rather than about self-reported exposures. Of the 4993 included respondents, 124 (2.5%) were identified as probably being exposed to formaldehyde in the course of their work [extrapolated to 2.6% of the Australian working population-265 000 (95% confidence interval 221 000-316 000) workers]. Most (87.1%) were male. About half worked in technical and trades occupations. In terms of industry, about half worked in the construction industry. The main circumstances of exposure were working with particle board or plywood typically through carpentry work, building maintenance, or sanding prior to painting; with the more common of other exposures circumstances being firefighters involved in fighting fires, fire overhaul, and clean-up or back-burning; and health workers using formaldehyde when sterilizing equipment or in a pathology laboratory setting. The use of control measures was inconsistent. Workers are exposed to formaldehyde in many different occupational circumstances. Information on the exposure circumstances can be used to support decisions on appropriate priorities for intervention and control of occupational exposure to formaldehyde, and estimates of burden of cancer arising from occupational exposure to formaldehyde

SO3 formation from the X-ray photolysis of SO2 astrophysical ice analogues: FTIR spectroscopy and thermodynamic investigations.

Science.gov (United States)

de Souza Bonfim, Víctor; Barbosa de Castilho, Roberto; Baptista, Leonardo; Pilling, Sergio

2017-10-11

In this combined experimental-theoretical work we focus on the physical and chemical changes induced by soft X-rays on sulfur dioxide (SO 2 ) ice at a very low temperature, in an attempt to clarify and quantify its survival and chemical changes in some astrophysical environments. SO 2 is an important constituent of some Jupiter moons and has also been observed in ices around protostars. The measurements were performed at the Brazilian Synchrotron Light Source (LNLS/CNPEM), in Campinas, Brazil. The SO 2 ice sample (12 K) was exposed to a broadband beam of mainly soft X-rays (6-2000 eV) and in situ analyses were performed by IR spectroscopy. The X-ray photodesorption yield (upper limit) was around 0.25 molecules per photon. The values determined for the effective destruction (SO 2 ) and formation (SO 3 ) cross sections were 2.5 × 10 -18 cm 2 and 2.1 × 10 -18 cm 2 , respectively. The chemical equilibrium (88% of SO 2 and 12% of SO 3 ) was reached after the fluence of 1.6 × 10 18 photons cm -2 . The SO 3 formation channels were studied at the second-order Møller-Plesset perturbation theory (MP2) level, which showed the three most favorable reaction routes (ΔH < -79 kcal mol -1 ) in simulated SO 2 ice: (i) SO + O 2 → SO 3 , (ii) SO 2 + O → SO 3 , and (iii) SO 2 + O + → SO 3 + + e - → SO 3 . The amorphous solid environment effect decreases the reactivity of intermediate species towards SO 3 formation, and ionic species are even more affected. The experimentally determined effective cross sections and theoretical reaction channels identified in this work allow us to better understand the chemical evolution of certain sulfur-rich astrophysical environments.

Quantification of Atmospheric Formaldehyde by Near-Infrared Cavity Ring-Down Spectroscopy

Science.gov (United States)

Rella, C.; Hoffnagle, J.; Fleck, D.; Kim-Hak, D.

2017-12-01

Formaldehyde is an important species in atmospheric chemistry, especially in urban environments, where it is a decay product of methane and volatile hydrocarbons. It is also a toxic, carcinogenic compound that can contaminate ambient air from incomplete combustion, or outgassing of commercial products such as adhesives used to fabricate plywood or to affix indoor carpeting. Formaldehyde has a clearly resolved ro-vibrational absorption spectrum that is well-suited to optical analysis of formaldehyde concentration. We describe an instrument based on cavity ring-down spectroscopy for the quantitative analysis of formaldehyde concentration in ambient air. The instrument has a precision (1-sigma) of about 1 ppb at a measurement rate of 1 second, and provides measurements of less than 100 ppt with averaging. The instrument provides stable measurements (drift < 1 ppb) over long periods of time (days). The instrument has been ruggedized for mobile applications, and with a fast response time of a couple of seconds, it is suitable for ground-based vehicle deployments for fenceline monitoring of formaldehyde emissions. In addition, we report on ambient atmospheric measurements at a 10m urban tower, which demonstrate the suitability of the instrument for applications in atmospheric chemistry.

Detailed Study of the Formation of Sugar Derivatives Produced from the UV Irradiation of Astrophysical Ice Analogs

Science.gov (United States)

Nuevo, Michel; Cooper, George; Saunders, John; Buffo, Christina E.; Materese, Christopher K.; Sandford, Scott A.

2018-01-01

Carbonaceous meteorites such as Murchison contain a large variety of organic compounds of astrobiological interest such as amino acids, other amphiphilic compounds, functionalized nitrogen heterocycles (including nucleobases), functionalized polycylic aromatic hydro-carbons (including quinones), and sugar derivatives. The presence of such a broad variety of organics in meteorites strongly suggests that molecules essential to life can form abiotically under astrophysical conditions. This hypothesis is strongly supported by laboratory studies in which astrophysical ice analogs (i.e., mixtures of H2O, CO, CO2, CH3OH, CH4, NH3, etc.) are subjected to ultraviolet (UV) irradiation at low temperature (less than 15 K) to simulate cold interstellar environments. These studies have shown that the organic residues recovered at room temperature after irradiation contain organic compounds that are very similar to those found in meteorites. No systematic search for the presence of sugar derivatives in laboratory residues had been carried out until the recent detection of ribose, the sugar of RNA, as well as other sugars, sugar alcohols, and sugar acids in one residue produced from the UV irradiation of an ice mixture containing H2O, CH3OH, and NH3 at 80 K. In this work, we present a detailed study of the formation of sugar derivatives contained in organic residues that are produced from the UV irradiation of ice mixtures of different starting compositions (H2O, CH3OH, CO, CO2, and/or NH3) at less than 15 K. While the presence of sugar alcohols, sugars, and sugar acids-in some cases with up to 6 carbon atoms-could be confirmed in all these residues, their distribution was shown to vary with the composition of the starting ices. In particular, only a few ices result in the formation of sugar derivatives displaying a distribution that resembles that of meteorites, in which sugar alcohols and sugar acids are very abundant while sugars are mostly absent.

Design of a formaldehyde photodissociation process for carbon and oxygen isotope separation

International Nuclear Information System (INIS)

Stern, R.C.; Scheibner, K.F.

1993-01-01

The current shortage of 18 O has revived interest in using one step UV photodissociation of formaldehyde to enrich 13 C, 17 O and 18 O. The frequency doubled output of the copper laser pumped dye laser system currently in operation at LLNL can be used to drive this dissociation. The authors use a simple kinetics model and their experience with Atomic Vapor Laser Isotope Separation (AVLIS) process design to examine the relative merits of different designs for a formaldehyde photodissociation process. Given values for the molecular photoabsorption cross section, partition function, spectroscopic selectivity, collisional exchange and quenching cross sections (all as parameters), they perform a partial optimization in the space of illuminated area, formaldehyde pressure in each stage, and formaldehyde residence time in each stage. They examine the effect of cascade design (heads and tails staging) on molecule and photon utilization for each of the three isotope separation missions, and look in one case at the system's response to different ratios of laser to formaldehyde costs. Finally, they examine the relative cost of enrichment as a function of isotope and product assay. Emphasis is as much on the process design methodology, which is general, as on the specific application to formaldehyde

Graphene oxide as efficient high-concentration formaldehyde scavenger and reutilization in supercapacitor.

Science.gov (United States)

Liang, Hongyu; Bu, Yongfeng; Zhang, Yutian; Zhang, Junyan

2015-04-15

Graphene oxide (GO) was investigated as a low-cost and high-efficient scavenger for high-concentration formaldehyde in alkali media. It showed very high removal capacity, 411 mg of formaldehyde per milligram of GO, and strong resistant to temperature changes. Additionally, the used GO can be easily renewed by a simple electrochemical method. By analyzing the componential and electrochemical characterizations of GO before and after use, the results showed that the degradation mechanism of formaldehyde is a collaborative process of chemical oxidation and physical adsorption, and the former dominates the degradation process. With the aid of oxygen-containing groups in GO, most formaldehyde can be easily oxidized by GO in alkaline media (this is equivalent to GO was reduced by formaldehyde). On the other hand, the used GO (reduced GO, noted as rGO) exhibits more ideal electronic double-layer capacitor (EDLC) feature than GO, along with higher rate capacitance (up to 136 F g(-1) at 50 A g(-1)). In short, GO is not only an efficient formaldehyde scavenger, but the used GO (rGO) can serve as promising electrical energy storage material. This study provides new insights for us to reutilize the discarded adsorbents generated from the environmental protection. Copyright © 2014 Elsevier Inc. All rights reserved.

Nitrogen Doped Graphene Supported Pt Nanoflowers as Electrocatalysts for Oxidation of Formaldehyde.

Science.gov (United States)

Xie, Aijuan; Zhou, Wenting; Luo, Shiping; Chen, Yu; Zhou, Xiaoqing; Chao, Yao

2017-02-01

A facile Pt nanoflowers/nitrogen-doped graphene (PtNFs/NG) electrocatalyst was prepared via depositing Pt nanoflowers (PtNFs) onto the nitrogen-doped graphene (NG) matrix with urea as the nitrogen source and PtNFs/NG modified glassy carbon electrode (GCE) was prepared by electro-chemical method. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectroscope, X-ray photoelectron spectroscopy (XPS) and Scanning electron microscope (SEM) were used to characterize the resulting composites. Also oxidation of formaldehyde on the resulting PtNFs/NG modified electrode was investigated. The influence of deposition time, electrodeposition potential and formaldehyde concentration on electrooxidation of formaldehyde was detected, the experimental results indicate the high performance of PtNFs/NG catalyst for formaldehyde oxidation is at electrodeposition time of 300 s with the applied potential of −0.3 V. Electrochemical process, electrocatalytic stability and chronoamperometry were also inspected, it was indicated that formalde-hyde oxidation reaction on the PtNFs/NG electrode is diffusion-controlled and PtNFs/NG exhibits a high catalytic activity, stability as well as excellent poisoning-tolerance towards formaldehyde oxidation, which is attributed to the synergistic effect of PtNFs and NG. It turns out that PtNFs/NG can be used in direct liquid-feed fuel cells as a promising alternative catalyst.

NO ICE HYDROGENATION: A SOLID PATHWAY TO NH2OH FORMATION IN SPACE

International Nuclear Information System (INIS)

Congiu, Emanuele; Dulieu, François; Chaabouni, Henda; Baouche, Saoud; Lemaire, Jean Louis; Fedoseev, Gleb; Ioppolo, Sergio; Lamberts, Thanja; Linnartz, Harold; Laffon, Carine; Parent, Philippe; Cuppen, Herma M.

2012-01-01

Icy dust grains in space act as catalytic surfaces onto which complex molecules form. These molecules are synthesized through exothermic reactions from precursor radicals and, mostly, hydrogen atom additions. Among the resulting products are species of biological relevance, such as hydroxylamine—NH 2 OH—a precursor molecule in the formation of amino acids. In this Letter, laboratory experiments are described that demonstrate NH 2 OH formation in interstellar ice analogs for astronomically relevant temperatures via successive hydrogenation reactions of solid nitric oxide (NO). Inclusion of the experimental results in an astrochemical gas-grain model proves the importance of a solid-state NO+H reaction channel as a starting point for prebiotic species in dark interstellar clouds and adds a new perspective to the way molecules of biological importance may form in space.

Injection Seeded Laser for Formaldehyde Differential Fluorescence Lidar

Directory of Open Access Journals (Sweden)

Schwemmer G.

2016-01-01

Full Text Available We describe the design and development of an injection seeded Nd:YVO4 laser for use in a differential fluorescence lidar for measuring atmospheric formaldehyde profiles. A high repetition rate Q-switched laser is modified to accept injection seed input to spectrally narrow and tune the output. The third harmonic output is used to excite formaldehyde (HCHO fluorescence when tuned to a HCHO absorption line. Spectral confirmation is made with the use of a photoacoustic cell and grating spectrometer.

Observations of Carbon Isotopic Fractionation in Interstellar Formaldehyde

Science.gov (United States)

Wirstrom, E. S.; Charnley, S. B.; Geppert, W. D.; Persson, C. M.

2012-01-01

Primitive Solar System materials (e.g. chondrites. IDPs, the Stardust sample) show large variations in isotopic composition of the major volatiles (H, C, N, and O ) even within samples, witnessing to various degrees of processing in the protosolar nebula. For ex ample. the very pronounced D enhancements observed in IDPs [I] . are only generated in the cold. dense component of the interstellar medium (ISM), or protoplanetary disks, through ion-molecule reactions in the presence of interstellar dust. If this isotopic anomaly has an interstellar origin, this leaves open the possibility for preservation of other isotopic signatures throughout the form ation of the Solar System. The most common form of carbon in the ISM is CO molecules, and there are two potential sources of C-13 fractionation in this reservoir: low temperature chemistry and selective photodissociation. While gas-phase chemistry in cold interstellar clouds preferentially incorporates C-13 into CO [2], the effect of self-shielding in the presence of UV radiation instead leads to a relative enhancement of the more abundant isotopologue, 12CO. Solar System organic material exhibit rather small fluctuations in delta C-13 as compared to delta N-15 and delta D [3][1], the reason for which is still unclear. However, the fact that both C-13 depleted and enhanced material exists could indicate an interstellar origin where the two fractionation processes have both played a part. Formaldehyde (H2CO) is observed in the gas-phase in a wide range of interstellar environments, as well as in cometary comae. It is proposed as an important reactant in the formation of more complex organic molecules in the heated environments around young stars, and formaldehyde polymers have been suggested as the common origin of chondritic insoluable organic matter (IOM) and cometary refractory organic solids [4]. The relatively high gas-phase abundance of H2CO observed in molecular clouds (10(exp- 9) - 10(exp- 8) relative to H2) makes

Destruction of nitric acid in purex process streams by formaldehyde treatment

International Nuclear Information System (INIS)

Kumar, S.V.; Nadkarni, M.N.; Mayankutty, P.C.; Pillai, N.S.; Shinde, S.S.

1974-01-01

Efficiency of destruction of nitric acid in purex process streams with formaldehyde has been studied as a function of initial acidity, uranium concentration, rate of addition of formaldehyde and temperature in the range 6 - 0.5M acid. Guidelines are suggested for the accurate calculations of the volume of formaldehyde needed to effect the required change of acidity at 100degC. Sodium nitrite has been established as a 'key' to initiate the reaction and water as an effective scrubber for collecting the acid fumes emanating from the reaction vessel. (author)

Guinea pig maximization tests with formaldehyde releasers. Results from two laboratories

DEFF Research Database (Denmark)

Andersen, Klaus Ejner; Boman, A; Hamann, K

1984-01-01

The guinea pig maximization test was used to evaluate the sensitizing potential of formaldehyde and 6 formaldehyde releasers (Forcide 78, Germall 115, Grotan BK, Grotan OX, KM 200 and Preventol D2). The tests were carried out in 2 laboratories (Copenhagen and Stockholm), and although we intended...... the procedures to be the same, discrepancies were observed, possibly due to the use of different animal strains, test concentrations and vehicles. The sensitizing potential was in general found to be stronger in Stockholm compared to Copenhagen: formaldehyde sensitized 50% of the guinea pigs in Copenhagen and 95...

Compact, Ultrasensitive Formaldehyde Monitor, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — This Small Business Innovative Research Phase I proposal seeks to develop an ultrasensitive, laser-based formaldehyde gas sensor system for airborne and ground-based...

Formaldehyde's Impact on Indoor Air Quality

Science.gov (United States)

Formaldehyde is an important chemical used widely by industry to manufacture building materials and numerous household products. It is also a by-product of combustion and certain other natural processes.

STS-48 ESC Earth observation of ice pack, Antarctic Ice Shelf

Science.gov (United States)

1991-01-01

STS-48 Earth observation taken aboard Discovery, Orbiter Vehicle (OV) 103, is of the breakup of pack ice along the periphery of the Antarctic Ice Shelf. Strong offshore winds, probably associated with katabatic downdrafts from the interior of the continent, are seen peeling off the edges of the ice shelf into long filaments of sea ice, icebergs, bergy bits, and growlers to flow northward into the South Atlantic Ocean. These photos are used to study ocean wind, tide and current patterns. Similar views photographed during previous missions, when analyzed with these recent views may yield information about regional ice drift and breakup of ice packs. The image was captured using an electronic still camera (ESC), was stored on a removable hard disk or small optical disk, and was converted to a format suitable for downlink transmission. The ESC documentation was part of Development Test Objective (DTO) 648, Electronic Still Photography.

Inactivation kinetics of formaldehyde on N-acetyl-β-D-glucosaminidase from Nile tilapia (Oreochromis niloticus).

Science.gov (United States)

Zhang, Wei-Ni; Bai, Ding-Ping; Lin, Xin-Yu; Chen, Qing-Xi; Huang, Xiao-Hong; Huang, Yi-Fan

2014-04-01

Formaldehyde is a widely used sanitizer in aquaculture in China, while the appropriate concentration is not available to be used effectively and without damage to tilapia much less to its reproductive function. N-acetyl-β-D-glucosaminidase (EC 3.2.1.52, NAGase), hydrolyzing the oligomers of N-acetyl-β-D-glucosamine into monomer, is proved to be correlated with reproduction of male animals. In this paper, NAGase from spermary of tilapia was chosen as the material to study the effects of formaldehyde on its activity in order to further investigate the effects of formaldehyde use on tilapia reproduction. The results showed the relationship between the residual enzyme activity and the concentration of formaldehyde was concentration dependent, and the IC50 value was estimated to be 3.2 ± 0.1 %. Appropriate concentration of formaldehyde leaded to competitive reversible inhibition on tilapia NAGase. Moreover, formaldehyde could reduce the thermal and pH stability of the enzyme. The inactivation kinetics of formaldehyde on the enzyme was studied using the kinetic method of substrate reaction. The inactivation model was setup, and the rate constants were determined. The results showed that the inactivation of formaldehyde on tilapia NAGase was a slow, reversible reaction with partially residual activity. The results will give some basis to determine the concentration of formaldehyde used in tilapia culture.

Synthesis and characterization of resorcinol–formaldehyde resin chars doped by zinc oxide

International Nuclear Information System (INIS)

Gun’ko, Vladimir M.; Bogatyrov, Viktor M.; Oranska, Olena I.; Urubkov, Iliya V.; Leboda, Roman; Charmas, Barbara; Skubiszewska-Zięba, Jadwiga

2014-01-01

Polycondensation polymerization of resorcinol–formaldehyde (RF) mixtures in water with addition of different amounts of zinc acetate and then carbonization of dried gels are studied to prepare ZnO doped chars. Zinc acetate as a catalyst of resorcinol–formaldehyde polycondensation affects structural features of the RF resin (RFR) and, therefore, the texture of chars prepared from Zn-doped RFR. The ZnO doped chars are characterized using thermogravimetry, low temperature nitrogen adsorption/desorption, Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and high resolution transmission electron microscopy (HRTEM). At a relatively high content of zinc acetate (1 mol per 10–40 mol of resorcinol) in the reaction mixture, the formation of crystallites of ZnO (zincite) occurs in a shape of straight nanorods of 20–130 nm in diameter and 1–3 μm in length. At a small content of zinc acetate (1 mol per 100–500 mol of resorcinol), ZnO in composites is XRD amorphous and does not form individual particles. The ZnO doped chars are pure nanoporous at a minimal ZnO content and nano-mesoporous or nano-meso-macroporous at a higher ZnO content.

29 CFR 1910.1048 - Formaldehyde.

Science.gov (United States)

2010-07-01

... resolve their disagreement, then the employer and the employee through their respective physicians shall... the disagreement of the prior physicians. (v) In the alternative, the employer and the employee or.... Employee exposure means the exposure to airborne formaldehyde which would occur without corrections for...

Glycine formation in CO2:CH4:NH3 ices induced by 0-70 eV electrons

Science.gov (United States)

Esmaili, Sasan; Bass, Andrew D.; Cloutier, Pierre; Sanche, Léon; Huels, Michael A.

2018-04-01

Glycine (Gly), the simplest amino-acid building-block of proteins, has been identified on icy dust grains in the interstellar medium, icy comets, and ice covered meteorites. These astrophysical ices contain simple molecules (e.g., CO2, H2O, CH4, HCN, and NH3) and are exposed to complex radiation fields, e.g., UV, γ, or X-rays, stellar/solar wind particles, or cosmic rays. While much current effort is focused on understanding the radiochemistry induced in these ices by high energy radiation, the effects of the abundant secondary low energy electrons (LEEs) it produces have been mostly assumed rather than studied. Here we present the results for the exposure of multilayer CO2:CH4:NH3 ice mixtures to 0-70 eV electrons under simulated astrophysical conditions. Mass selected temperature programmed desorption (TPD) of our electron irradiated films reveals multiple products, most notably intact glycine, which is supported by control measurements of both irradiated or un-irradiated binary mixture films, and un-irradiated CO2:CH4:NH3 ices spiked with Gly. The threshold of Gly formation by LEEs is near 9 eV, while the TPD analysis of Gly film growth allows us to determine the "quantum" yield for 70 eV electrons to be about 0.004 Gly per incident electron. Our results show that simple amino acids can be formed directly from simple molecular ingredients, none of which possess preformed C—C or C—N bonds, by the copious secondary LEEs that are generated by ionizing radiation in astrophysical ices.

Low-density carbonized resorcinol-formaldehyde foams

International Nuclear Information System (INIS)

Kong, F.M.; Buckley, S.R.; Giles, C.L. Jr.; Haendler, B.L.; Hair, L.M.; Letts, S.A.; Overturf, G.E. III; Price, C.W.; Cook, R.C.

1991-01-01

This report documents research and development on resorcinol- formaldehyde-based foam materials conducted between 1986 and June 1990, when the effort was discontinued. The foams discussed are resorcinol-formaldehyde (RF) foam, carbonized RF (CRF) foam, and two composite foams, a polystyrene/RF (PS/RF) foam and its carbonized derivative (CPR). The RF foams are synthesized by the polycondensation of resorcinol with formaldehyde in a slightly basic solution. Their structure and density depend strongly on the concentration of the sodium carbonate catalyst. The have an interconnected bead structure similar to that of silica aerogels; bead sizes range from 30 to 130 Angstrom, and cell sizes are less than 0.1 μm. We have achieved densities of 16 to 200 mg/cm 3 . The RF foams can be pyrolyzed in an inert atmosphere to form a vitreous carbon foam (CRF), which has a similar microstructure but much higher mechanical strength. The PS/RF foams are obtained by filling the 2- to 3-μm cells of PS foam (a low-density hydrocarbon foam we have developed) with RF. The resultant foams have the outstanding handling and machinability of the PS foam matrix and the small cell size of RF. Pyrolyzing PS/RF foams causes depolymerization and loss of the PS; the resulting CPR foams have a structure similar to the PS foams in which CRF both replicates and fills the PS cells

Physical controls on the storage of methane in land fast sea ice

DEFF Research Database (Denmark)

Zhou, Jiayun; Tison, Jean Louis; Carnat, Gauthier

2014-01-01

regulated the storage of CH4 in sea ice: bubble formation and sea ice permeability. Gas bubble formation from solubility changes had favoured the accumulation of CH4 in the ice at the beginning of ice growth. CH4 retention in sea ice was then twice as efficient as that of salt; this also explains...... the overall higher CH4 concentrations in brine than in the under-ice water. As sea ice thickened, gas bubble formation became less efficient so that CH4 was then mainly trapped in the dissolved state. The increase of sea ice permeability during ice melt marks the end of CH4 storage.......We report on methane (CH4) dynamics in landfast sea ice, brine and under-ice seawater at Barrow in 2009. The CH4 concentrations in under-ice water ranged between 25.9 and 116.4 nmol L−1sw, indicating a superaturation of 700 to 3100% relative to the atmosphere. In comparison, the CH4 concentrations...

Molecular hydrogen formation on surfaces of astrophysical interest: first results on water ice at very low temperature and on graphite at high temperature

International Nuclear Information System (INIS)

Baouche, Saoud

2004-01-01

As the generally admitted mechanism of formation of the H_2 molecule in the interstellar medium (ISM) is a catalytic reaction between two atoms of H on the surface of cosmic powder grains, where grains are supposed to be carbons or silicates and could have ice coats, this research thesis aims at providing some elements about the efficiency of this reaction, what happens to the bound energy released after formation of the H_2 molecule. The author first describes the FORMOLISM experiment (Formation of molecule in the ISM), and then reports the study of the source of H or D atoms which is a very important component of the experiment. He reports and comments results obtained on the formation of H_2 and D_2 molecules on amorphous water ice. He reports the study of the dynamics of formation of the D_2 molecule on a graphite surface by using the laser-aided associative adsorption technique

Hydroxyl radical reactivity at the air-ice interface

Directory of Open Access Journals (Sweden)

T. F. Kahan

2010-01-01

Full Text Available Hydroxyl radicals are important oxidants in the atmosphere and in natural waters. They are also expected to be important in snow and ice, but their reactivity has not been widely studied in frozen aqueous solution. We have developed a spectroscopic probe to monitor the formation and reactions of hydroxyl radicals in situ. Hydroxyl radicals are produced in aqueous solution via the photolysis of nitrite, nitrate, and hydrogen peroxide, and react rapidly with benzene to form phenol. Similar phenol formation rates were observed in aqueous solution and bulk ice. However, no reaction was observed at air-ice interfaces, or when bulk ice samples were crushed prior to photolysis to increase their surface area. We also monitored the heterogeneous reaction between benzene present at air-water and air-ice interfaces with gas-phase OH produced from HONO photolysis. Rapid phenol formation was observed on water surfaces, but no reaction was observed at the surface of ice. Under the same conditions, we observed rapid loss of the polycyclic aromatic hydrocarbon (PAH anthracene at air-water interfaces, but no loss was observed at air-ice interfaces. Our results suggest that the reactivity of hydroxyl radicals toward aromatic organics is similar in bulk ice samples and in aqueous solution, but is significantly suppressed in the quasi-liquid layer (QLL that exists at air-ice interfaces.

Portable formaldehyde monitoring device using porous glass sensor and its applications in indoor air quality studies.

Science.gov (United States)

Maruo, Yasuko Yamada; Nakamura, Jiro

2011-09-30

We have developed a portable device for formaldehyde monitoring with both high sensitivity and high temporal resolution, and carried out indoor air formaldehyde concentration analysis. The absorbance difference of the sensor element was measured in the monitoring device at regular intervals of, for example, one hour or 30 min, and the result was converted into the formaldehyde concentration. This was possible because we found that the lutidine derivative that was formed as a yellow product of the reaction between 1-phenyl-1,3-butandione and formaldehyde was stable in porous glass for at least six months. We estimated the reaction rate and to be 0.049 min(-1) and the reaction occurred quickly enough for us to monitor hourly changes in the formaldehyde concentration. The detection limit was 5 μg m(-3) h. We achieved hourly formaldehyde monitoring using the developed device under several indoor conditions, and estimated the air exchange rate and formaldehyde adsorption rate, which we adopted as a new term in the mass balance equation for formaldehyde, in one office. Copyright © 2011 Elsevier B.V. All rights reserved.

Cells deficient in the FANC/BRCA pathway are hypersensitive to plasma levels of formaldehyde.

Science.gov (United States)

Ridpath, John R; Nakamura, Ayumi; Tano, Keizo; Luke, April M; Sonoda, Eiichiro; Arakawa, Hiroshi; Buerstedde, Jean-Marie; Gillespie, David A F; Sale, Julian E; Yamazoe, Mitsuyoshi; Bishop, Douglas K; Takata, Minoru; Takeda, Shunichi; Watanabe, Masami; Swenberg, James A; Nakamura, Jun

2007-12-01

Formaldehyde is an aliphatic monoaldehyde and is a highly reactive environmental human carcinogen. Whereas humans are continuously exposed to exogenous formaldehyde, this reactive aldehyde is a naturally occurring biological compound that is present in human plasma at concentrations ranging from 13 to 97 micromol/L. It has been well documented that DNA-protein crosslinks (DPC) likely play an important role with regard to the genotoxicity and carcinogenicity of formaldehyde. However, little is known about which DNA damage response pathways are essential for cells to counteract formaldehyde. In the present study, we first assessed the DNA damage response to plasma levels of formaldehyde using chicken DT40 cells with targeted mutations in various DNA repair genes. Here, we show that the hypersensitivity to formaldehyde is detected in DT40 mutants deficient in the BRCA/FANC pathway, homologous recombination, or translesion DNA synthesis. In addition, FANCD2-deficient DT40 cells are hypersensitive to acetaldehyde, but not to acrolein, crotonaldehyde, glyoxal, and methylglyoxal. Human cells deficient in FANCC and FANCG are also hypersensitive to plasma levels of formaldehyde. These results indicate that the BRCA/FANC pathway is essential to counteract DPCs caused by aliphatic monoaldehydes. Based on the results obtained in the present study, we are currently proposing that endogenous formaldehyde might have an effect on highly proliferating cells, such as bone marrow cells, as well as an etiology of cancer in Fanconi anemia patients.

Surface modification of bone char for removal of formaldehyde from air

Energy Technology Data Exchange (ETDEWEB)

Rezaee, Abbas, E-mail: rezaee@modares.ac.ir [Environmental Health Department, Faculty of Medical Sciences, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Rangkooy, Hosseinali [Environmental Health Department, Faculty of Medical Sciences, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Occupational Health Department, Faculty of Health, Jondishapor Medical Sciences University, Ahvaz (Iran, Islamic Republic of); Jonidi-Jafari, Ahmad; Khavanin, Ali [Environmental Health Department, Faculty of Medical Sciences, Tarbiat Modares University, Tehran (Iran, Islamic Republic of)

2013-12-01

The aim of this study was to evaluate the adsorption performance of bone char (BC) modified with acetic acid for formaldehyde removal from polluted air. The porous structure, surface characteristics and functional groups involved in formaldehyde adsorption were determined using the Brunauer–Emmett–Teller (BET) method, scanning electron microscope (SEM) equipped with energy dispersive X-ray (EDX) and Fourier transform infrared spectroscopy (FTIR), respectively. It was found that the modified BC has a higher specific surface area than the original BC. The maximum surface area of the modified BC was 118.58 m{sup 2}/g. The FTIR spectrum of modified BC indicated that the hydroxyl and carboxyl groups on the BC surface played a significant role in the adsorption of formaldehyde by modified BC. The breakthrough, equilibrium time and adsorption capacity of modified BC were greater than the original BC. Moreover, the results showed that at initial concentrations of 20, 50, 100 and 200 mg/L, the equilibrium times for BC and modified BC were 85, 75, 65 and 45 min and 95, 85, 70 and 50 min, respectively. It seems that the formaldehyde adsorption capacity of modified BC depends on both physical and chemical properties. These results showed that modified BC can be used as an efficient adsorbent for formaldehyde removal.

Hydrogen-Bonding Surfaces for Ice Mitigation

Science.gov (United States)

Smith, Joseph G., Jr.; Wohl, Christopher J.; Kreeger, Richard E.; Hadley, Kevin R.; McDougall, Nicholas

2014-01-01

Ice formation on aircraft, either on the ground or in-flight, is a major safety issue. While ground icing events occur predominantly during the winter months, in-flight icing can happen anytime during the year. The latter is more problematic since it could result in increased drag and loss of lift. Under a Phase I ARMD NARI Seedling Activity, coated aluminum surfaces possessing hydrogen-bonding groups were under investigation for mitigating ice formation. Hydroxyl and methyl terminated dimethylethoxysilanes were prepared via known chemistries and characterized by spectroscopic methods. These materials were subsequently used to coat aluminum surfaces. Surface compositions were based on pure hydroxyl and methyl terminated species as well as mixtures of the two. Coated surfaces were characterized by contact angle goniometry. Receding water contact angle data suggested several potential surfaces that may exhibit reduced ice adhesion. Qualitative icing experiments performed under representative environmental temperatures using supercooled distilled water delivered via spray coating were inconclusive. Molecular modeling studies suggested that chain mobility affected the interface between ice and the surface more than terminal group chemical composition. Chain mobility resulted from the creation of "pockets" of increased free volume for longer chains to occupy.

INFRARED SPECTROSCOPIC SURVEY OF THE QUIESCENT MEDIUM OF NEARBY CLOUDS. I. ICE FORMATION AND GRAIN GROWTH IN LUPUS

Energy Technology Data Exchange (ETDEWEB)

Boogert, A. C. A. [IPAC, NASA Herschel Science Center, Mail Code 100-22, California Institute of Technology, Pasadena, CA 91125 (United States); Chiar, J. E. [SETI Institute, Carl Sagan Center, 189 Bernardo Avenue, Mountain View, CA 94043 (United States); Knez, C.; Mundy, L. G. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Öberg, K. I. [Departments of Chemistry and Astronomy, University of Virginia, Charlottesville, VA 22904 (United States); Pendleton, Y. J. [Solar System Exploration Research Virtual Institute, NASA Ames Research Center, Moffett Field, CA 94035 (United States); Tielens, A. G. G. M.; Van Dishoeck, E. F., E-mail: aboogert@ipac.caltech.edu [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands)

2013-11-01

Infrared photometry and spectroscopy (1-25 μm) of background stars reddened by the Lupus molecular cloud complex are used to determine the properties of grains and the composition of ices before they are incorporated into circumstellar envelopes and disks. H{sub 2}O ices form at extinctions of A{sub K} = 0.25 ± 0.07 mag (A{sub V} = 2.1 ± 0.6). Such a low ice formation threshold is consistent with the absence of nearby hot stars. Overall, the Lupus clouds are in an early chemical phase. The abundance of H{sub 2}O ice (2.3 ± 0.1 × 10{sup –5} relative to N{sub H}) is typical for quiescent regions, but lower by a factor of three to four compared to dense envelopes of young stellar objects. The low solid CH{sub 3}OH abundance (<3%-8% relative to H{sub 2}O) indicates a low gas phase H/CO ratio, which is consistent with the observed incomplete CO freeze out. Furthermore it is found that the grains in Lupus experienced growth by coagulation. The mid-infrared (>5 μm) continuum extinction relative to A{sub K} increases as a function of A{sub K}. Most Lupus lines of sight are well fitted with empirically derived extinction curves corresponding to R{sub V} ∼ 3.5 (A{sub K} = 0.71) and R{sub V} ∼ 5.0 (A{sub K} = 1.47). For lines of sight with A{sub K} > 1.0 mag, the τ{sub 9.7}/A{sub K} ratio is a factor of two lower compared to the diffuse medium. Below 1.0 mag, values scatter between the dense and diffuse medium ratios. The absence of a gradual transition between diffuse and dense medium-type dust indicates that local conditions matter in the process that sets the τ{sub 9.7}/A{sub K} ratio. This process is likely related to grain growth by coagulation, as traced by the A{sub 7.4}/A{sub K} continuum extinction ratio, but not to ice mantle formation. Conversely, grains acquire ice mantles before the process of coagulation starts.

24 CFR 3280.308 - Formaldehyde emission controls for certain wood products.

Science.gov (United States)

2010-04-01

... 24 Housing and Urban Development 5 2010-04-01 2010-04-01 false Formaldehyde emission controls for certain wood products. 3280.308 Section 3280.308 Housing and Urban Development Regulations Relating to... Body and Frame Construction Requirements § 3280.308 Formaldehyde emission controls for certain wood...

STABLE ISOTOPE GEOCHEMISTRY OF MASSIVE ICE

Directory of Open Access Journals (Sweden)

Yurij K. Vasil’chuk

2016-01-01

Full Text Available The paper summarises stable-isotope research on massive ice in the Russian and North American Arctic, and includes the latest understanding of massive-ice formation. A new classification of massive-ice complexes is proposed, encompassing the range and variabilityof massive ice. It distinguishes two new categories of massive-ice complexes: homogeneousmassive-ice complexes have a similar structure, properties and genesis throughout, whereasheterogeneous massive-ice complexes vary spatially (in their structure and properties andgenetically within a locality and consist of two or more homogeneous massive-ice bodies.Analysis of pollen and spores in massive ice from Subarctic regions and from ice and snow cover of Arctic ice caps assists with interpretation of the origin of massive ice. Radiocarbon ages of massive ice and host sediments are considered together with isotope values of heavy oxygen and deuterium from massive ice plotted at a uniform scale in order to assist interpretation and correlation of the ice.

short communication quantitative determination of formaldehyde

African Journals Online (AJOL)

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irritation, respiration, asthma and pulmonary edema have been reported previously [1]. ... for improving the capabilities, performing more reliable models and achieving more ... Formaldehyde was added to the Fluoral P solution in a 1:1 volume.

Biofiltration of waste gases containing a mixture of formaldehyde and methanol

Energy Technology Data Exchange (ETDEWEB)

Prado, O.J.; Veiga, M.C.; Kennes, C. [Chemical Engineering Lab., Faculty of Sciences, Univ. of La Coruna, La Coruna (Spain)

2004-07-01

Several biofilters and biotrickling filters were used for the treatment of a mixture of formaldehyde and methanol; and their efficiencies were compared. Results obtained with three different inert filter bed materials (lava rock, perlite, activated carbon) suggested that the packing material had only little influence on the performance. The best results were obtained in a biotrickling filter packed with lava rock and fed a nutrient solution that was renewed weekly. A maximum formaldehyde elimination capacity of 180 g m{sup -3} h{sup -1} was reached, while the methanol elimination capacity rose occasionally to more than 600 g m{sup -3} h{sup -1}. Formaldehyde degradation was affected by the inlet methanol concentration. Several combinations of load vs empty bed residence time (EBRTs of 71.9, 46.5, 30.0, 20.7 s) were studied, reaching a formaldehyde elimination capacity of 112 g m{sup -3} h{sup -1} with about 80% removal efficiency at the lowest EBRT (20.7 s). (orig.)

Biofiltration of waste gases containing a mixture of formaldehyde and methanol.

Science.gov (United States)

Prado, Oscar J; Veiga, María C; Kennes, Christian

2004-08-01

Several biofilters and biotrickling filters were used for the treatment of a mixture of formaldehyde and methanol; and their efficiencies were compared. Results obtained with three different inert filter bed materials (lava rock, perlite, activated carbon) suggested that the packing material had only little influence on the performance. The best results were obtained in a biotrickling filter packed with lava rock and fed a nutrient solution that was renewed weekly. A maximum formaldehyde elimination capacity of 180 g m(-3) h(-1) was reached, while the methanol elimination capacity rose occasionally to more than 600 g m(-3) h(-1). Formaldehyde degradation was affected by the inlet methanol concentration. Several combinations of load vs empty bed residence time (EBRTs of 71.9, 46.5, 30.0, 20.7 s) were studied, reaching a formaldehyde elimination capacity of 112 g m(-3) h(-1) with about 80% removal efficiency at the lowest EBRT (20.7 s).

Determination of free formaldehyde in cosmetics containing formaldehyde-releasing preservatives by reversed-phase dispersive liquid-liquid microextraction and liquid chromatography with post-column derivatization.

Science.gov (United States)

Miralles, Pablo; Chisvert, Alberto; Alonso, M José; Hernandorena, Sandra; Salvador, Amparo

2018-03-30

An analytical method for the determination of traces of formaldehyde in cosmetic products containing formaldehyde-releasing preservatives has been developed. The method is based on reversed-phase dispersive liquid-liquid microextraction (RP-DLLME), that allows the extraction of highly polar compounds, followed by liquid chromatography-ultraviolet/visible (LC-UV/vis) determination with post-column derivatization. The variables involved in the RP-DLLME process were studied to provide the best enrichment factors. Under the selected conditions, a mixture of 500 μL of acetonitrile (disperser solvent) and 50 μL of water (extraction solvent) was rapidly injected into 5 mL of toluene sample solution. The extracts were injected into the LC-UV/vis system using phosphate buffer 6 mmol L -1 at pH 2 as mobile phase. After chromatographic separation, the eluate merged with a flow stream of pentane-2,4-dione in ammonium acetate solution as derivatizing reagent and passed throughout a post-column reactor at 85 °C in order to derivatize formaldehyde into 3,5-diacetyl-1,4-dihydrolutidine, according to Hantzsch reaction, which was finally measured spectrophotometrically at 407 nm. The method was successfully validated showing good linearity, an enrichment factor of 86 ± 2, limits of detection and quantification of 0.7 and 2.3 ng mL -1 , respectively, and good repeatability (RSD < 9.2%). Finally, the proposed analytical method was applied to the determination of formaldehyde in different commercial cosmetic samples containing formaldehyde-releasing preservatives, such as bronopol, diazolidinyl urea, imidazolidinyl urea, and DMDM hydantoin, with good relative recovery values (91-113%) thus showing that matrix effects were negligible. The good analytical features of the proposed method besides of its simplicity and affordability, make it useful to carry out the quality control of cosmetic products containing formaldehyde-releasing preservatives. Copyright �

FORMATION OF S-BEARING SPECIES BY VUV/EUV IRRADIATION OF H2S-CONTAINING ICE MIXTURES: PHOTON ENERGY AND CARBON SOURCE EFFECTS

International Nuclear Information System (INIS)

Chen, Y.-J.; Juang, K.-J.; Qiu, J.-M.; Chu, C.-C.; Yih, T.-S.; Nuevo, M.; Jiménez-Escobar, A.; Muñoz Caro, G. M.; Wu, C.-Y. R.; Fung, H.-S.; Ip, W.-H.

2015-01-01

Carbonyl sulfide (OCS) is a key molecule in astrobiology that acts as a catalyst in peptide synthesis by coupling amino acids. Experimental studies suggest that hydrogen sulfide (H 2 S), a precursor of OCS, could be present in astrophysical environments. In the present study, we used a microwave-discharge hydrogen-flow lamp, simulating the interstellar UV field, and a monochromatic synchrotron light beam to irradiate CO:H 2 S and CO 2 :H 2 S ice mixtures at 14 K with vacuum ultraviolet (VUV) or extreme ultraviolet (EUV) photons in order to study the effect of the photon energy and carbon source on the formation mechanisms and production yields of S-containing products (CS 2 , OCS, SO 2 , etc.). Results show that (1) the photo-induced OCS production efficiency in CO:H 2 S ice mixtures is higher than that of CO 2 :H 2 S ice mixtures; (2) a lower concentration of H 2 S enhances the production efficiency of OCS in both ice mixtures; and (3) the formation pathways of CS 2 differ significantly upon VUV and EUV irradiations. Furthermore, CS 2 was produced only after VUV photoprocessing of CO:H 2 S ices, while the VUV-induced production of SO 2 occurred only in CO 2 :H 2 S ice mixtures. More generally, the production yields of OCS, H 2 S 2 , and CS 2 were studied as a function of the irradiation photon energy. Heavy S-bearing compounds were also observed using mass spectrometry during the warm-up of VUV/EUV-irradiated CO:H 2 S ice mixtures. The presence of S-polymers in dust grains may account for the missing sulfur in dense clouds and circumstellar environments

From ice to gas : constraining the desorption processes of interstellar ices

NARCIS (Netherlands)

Fayolle, Edith Carine

2013-01-01

The presence of icy mantles on interstellar dust grains play a key role in the formation of molecules observed at all stages of star formation. This thesis addresses thermal and UV-induced ice sublimation. Using state of the art laboratory experiments and synchrotron-based UV radiation, the

Brief Communication: Mapping river ice using drones and structure from motion

Science.gov (United States)

Alfredsen, Knut; Haas, Christian; Tuhtan, Jeffrey A.; Zinke, Peggy

2018-02-01

In cold climate regions, the formation and break-up of river ice is important for river morphology, winter water supply, and riparian and instream ecology as well as for hydraulic engineering. Data on river ice is therefore significant, both to understand river ice processes directly and to assess ice effects on other systems. Ice measurement is complicated due to difficult site access, the inherent complexity of ice formations, and the potential danger involved in carrying out on-ice measurements. Remote sensing methods are therefore highly useful, and data from satellite-based sensors and, increasingly, aerial and terrestrial imagery are currently applied. Access to low cost drone systems with quality cameras and structure from motion software opens up a new possibility for mapping complex ice formations. Through this method, a georeferenced surface model can be built and data on ice thickness, spatial distribution, and volume can be extracted without accessing the ice, and with considerably fewer measurement efforts compared to traditional surveying methods. A methodology applied to ice mapping is outlined here, and examples are shown of how to successfully derive quantitative data on ice processes.

Effects of de-icing chemicals sodium chloride and potassium formate on cadmium solubility in a coarse mineral soil

Energy Technology Data Exchange (ETDEWEB)

Rasa, Kimmo [Department of Applied Chemistry and Microbiology, University of Helsinki, P.O. Box 27, FIN-00014, University of Helsinki (Finland)]. E-mail: kimmo.rasa@helsinki.fi; Peltovuori, Tommi [Department of Applied Chemistry and Microbiology, University of Helsinki, P.O. Box 27, FIN-00014, University of Helsinki (Finland); Hartikainen, Helinae [Department of Applied Chemistry and Microbiology, University of Helsinki, P.O. Box 27, FIN-00014, University of Helsinki (Finland)

2006-08-01

Excessive use of sodium chloride (NaCl) as de-icing chemical causes environmental problems, such as elevated chloride concentrations in groundwater. On vulnerable sites, this can be avoided by using alternative organic de-icing chemicals, such as potassium formate (KHCOO). The environmental impacts of KCHOO are, however, not well known. This study reports the potential effects of NaCl and KCHOO on mechanisms controlling the mobility of cadmium (Cd) in roadside soils as a result of vehicular traffic. Changes in the solubility of Cd in a coarse mineral soil treated with these two de-icing chemicals were studied in a 50-day incubation experiment under four different moisture and temperature combinations and an initial soil Cd concentration of 3 mg kg{sup -1}. After incubation, the distribution of soil Cd into different fractions was analyzed using a sequential extraction method. Soil pH and soil redox potential were recorded and the occurrence of Cd-Cl complexes in the soil was estimated using published stability constants. During incubation, KCHOO lowered the soil redox potential, but this was not accompanied by a decrease in the sorption capacity of oxides and the release of oxide-bound Cd into soil solution. On the other hand, elevated pH (from 4.3 to 6.7-8.5) in the formate treatments increased the sorption of Cd onto the oxide surfaces (up to 80% of total sorbed Cd). In the NaCl treatments, cation competition and formation of Cd-Cl complexes increased the water-soluble Cd fraction. Consequently, the amount of bioavailable Cd was 3.5 times smaller in the KCHOO than in the NaCl treatments.

Pond Hockey on Whitmore Lacus: the Formation of Ponds and Ethane Ice Deposits Following Storm Events on Titan

Science.gov (United States)

Steckloff, Jordan; Soderblom, Jason M.

2017-10-01

Cassini ISS observations reveled regions, later identified as topographic low spots (Soderblom et al. 2014, DPS) on Saturn’s moon Titan become significantly darker (lower albedo) following storm events (Turtle et al. 2009, GRL; 2011, Science), suggesting pools of liquid hydrocarbon mixtures (predominantly methane-ethane-nitrogen). However, these dark ponds then significantly brighten (higher albedo relative to pre-storm albedo), before fading to their pre-storm albedos (Barnes et al. 2013 Planet. Sci; Soderblom et al. 2014, DPS). We interpret these data to be the result of ethane ice formation, which cools from evaporation of methane. The formation of ethane ices results from a unique sequence of thermophysical processes. Initially, the methane in the ternary mixture evaporates, cooling the pond. Nitrogen, dissolved primarily in the methane, exsolves, further cooling the liquid. However, because nitrogen is significantly more soluble in cooler methane-hydrocarbon mixtures, the relative concentration of nitrogen in the solution increases as it cools. This increased nitrogen fraction increases the density of the pond, as nitrogen is significantly more dense thane methane or ethane (pure ethane’s density is intermediate to that of methane and nitrogen). At around ~85 K the mixture is as dense as pure liquid ethane. Thus, further evaporative methane loss and cooling at the pond’s surface leads to a chemical stratification, with an increasingly ethane rich epilimnion (surface layer) overlying a methane rich hypolimnion (subsurface layer). Further evaporation of methane from the ethane-rich epilimnion drives its temperature and composition toward the methane-ethane-nitrogen liquidus curve, causing pure ethane ice to precipitate out of solution and settle to the bottom of the pool. This settling would obscure the ethane ice from Cassini VIMS and ISS, which would instead continue to appear as a dark pond on the surface. As the ethane precipitates out completely, a

Relationship between formaldehyde and quaternium-15 contact allergy. Influence of strength of patch test reactions

NARCIS (Netherlands)

de Groot, Anton C.; Blok, Janine; Coenraads, Pieter-Jan

2010-01-01

Objectives: To test our hypothesis that patients with stronger patch test reactions to formaldehyde are more likely to react to quaternium-15, attesting to the aetiological role for formaldehyde in such co-reactivity. Methods: Retrospective analysis of all patients patch tested with formaldehyde and

Synthesis of Formate Esters and Formamides Using an Au/TiO2-Catalyzed Aerobic Oxidative Coupling of Paraformaldehyde

Directory of Open Access Journals (Sweden)

Ioannis Metaxas

2017-12-01

Full Text Available A simple method for the synthesis of formate esters and formamides is presented based on the Au/TiO2-catalyzed aerobic oxidative coupling between alcohols or amines and formaldehyde. The suitable form of formaldehyde is paraformaldehyde, as cyclic trimeric 1,3,5-trioxane is inactive. The reaction proceeds via the formation of an intermediate hemiacetal or hemiaminal, respectively, followed by the Au nanoparticle-catalyzed aerobic oxidation of the intermediate. Typically, the oxidative coupling between formaldehyde (2 equiv and amines occurs quantitatively at room temperature within 4 h, and there is no need to add a base as in analogous coupling reactions. The oxidative coupling between formaldehyde (typically 3 equiv and alcohols is unprecedented and occurs more slowly, yet in good to excellent yields and selectivity. Minor side-products (2–12% from the acetalization of formaldehyde by the alcohol are also formed. The catalyst is recyclable and can be reused after a simple filtration in five consecutive runs with a small loss of activity.

Effect of electric field on adsorption of formaldehyde by β-cellobiose in micro-scale

Science.gov (United States)

Xu, Bo; Chen, Zhenqian

2018-05-01

To provide a microcosmic theoretical support for the reduction of formaldehyde in building material by the effect of electric fields, the adsorption between formaldehyde molecule and β-cellobiose was studied by density function theory (DFT). Details of geometric structures, molecule bonds and adsorption energy were discussed respectively. The obtained results indicated the energy of formaldehyde molecule decreased while the energy of β-cellobiose increased with greater electric intensity. In addition, the adsorption energy between formaldehyde molecule and β-cellobiose was greatly influenced by external electric field. The adsorption energy reduced gradually with greater electric intensity, and the changing curve of adsorption energy could be fitted as an exponential function, verified by the experiment. The results of this study confirmed the external electric field would be a good strategy for decreasing formaldehyde within building materials in the microcosmic view.

Icing Simulation Research Supporting the Ice-Accretion Testing of Large-Scale Swept-Wing Models

Science.gov (United States)

Yadlin, Yoram; Monnig, Jaime T.; Malone, Adam M.; Paul, Bernard P.

2018-01-01

The work summarized in this report is a continuation of NASA's Large-Scale, Swept-Wing Test Articles Fabrication; Research and Test Support for NASA IRT contract (NNC10BA05 -NNC14TA36T) performed by Boeing under the NASA Research and Technology for Aerospace Propulsion Systems (RTAPS) contract. In the study conducted under RTAPS, a series of icing tests in the Icing Research Tunnel (IRT) have been conducted to characterize ice formations on large-scale swept wings representative of modern commercial transport airplanes. The outcome of that campaign was a large database of ice-accretion geometries that can be used for subsequent aerodynamic evaluation in other experimental facilities and for validation of ice-accretion prediction codes.

Ice bridges and ridges in the Maxwell-EB sea ice rheology

Directory of Open Access Journals (Sweden)

V. Dansereau

2017-09-01

Full Text Available This paper presents a first implementation of a new rheological model for sea ice on geophysical scales. This continuum model, called Maxwell elasto-brittle (Maxwell-EB, is based on a Maxwell constitutive law, a progressive damage mechanism that is coupled to both the elastic modulus and apparent viscosity of the ice cover and a Mohr–Coulomb damage criterion that allows for pure (uniaxial and biaxial tensile strength. The model is tested on the basis of its capability to reproduce the complex mechanical and dynamical behaviour of sea ice drifting through a narrow passage. Idealized as well as realistic simulations of the flow of ice through Nares Strait are presented. These demonstrate that the model reproduces the formation of stable ice bridges as well as the stoppage of the flow, a phenomenon occurring within numerous channels of the Arctic. In agreement with observations, the model captures the propagation of damage along narrow arch-like kinematic features, the discontinuities in the velocity field across these features dividing the ice cover into floes, the strong spatial localization of the thickest, ridged ice, the presence of landfast ice in bays and fjords and the opening of polynyas downstream of the strait. The model represents various dynamical behaviours linked to an overall weakening of the ice cover and to the shorter lifespan of ice bridges, with implications in terms of increased ice export through narrow outflow pathways of the Arctic.

Ice bridges and ridges in the Maxwell-EB sea ice rheology

Science.gov (United States)

Dansereau, Véronique; Weiss, Jérôme; Saramito, Pierre; Lattes, Philippe; Coche, Edmond

2017-09-01

This paper presents a first implementation of a new rheological model for sea ice on geophysical scales. This continuum model, called Maxwell elasto-brittle (Maxwell-EB), is based on a Maxwell constitutive law, a progressive damage mechanism that is coupled to both the elastic modulus and apparent viscosity of the ice cover and a Mohr-Coulomb damage criterion that allows for pure (uniaxial and biaxial) tensile strength. The model is tested on the basis of its capability to reproduce the complex mechanical and dynamical behaviour of sea ice drifting through a narrow passage. Idealized as well as realistic simulations of the flow of ice through Nares Strait are presented. These demonstrate that the model reproduces the formation of stable ice bridges as well as the stoppage of the flow, a phenomenon occurring within numerous channels of the Arctic. In agreement with observations, the model captures the propagation of damage along narrow arch-like kinematic features, the discontinuities in the velocity field across these features dividing the ice cover into floes, the strong spatial localization of the thickest, ridged ice, the presence of landfast ice in bays and fjords and the opening of polynyas downstream of the strait. The model represents various dynamical behaviours linked to an overall weakening of the ice cover and to the shorter lifespan of ice bridges, with implications in terms of increased ice export through narrow outflow pathways of the Arctic.

NO ICE HYDROGENATION: A SOLID PATHWAY TO NH{sub 2}OH FORMATION IN SPACE

Energy Technology Data Exchange (ETDEWEB)

Congiu, Emanuele; Dulieu, Francois; Chaabouni, Henda; Baouche, Saoud; Lemaire, Jean Louis [LERMA-LAMAp, Universite de Cergy-Pontoise, Observatoire de Paris, ENS, UPMC, UMR 8112 du CNRS, 5 Mail Gay Lussac, 95000 Cergy Pontoise Cedex (France); Fedoseev, Gleb; Ioppolo, Sergio; Lamberts, Thanja; Linnartz, Harold [Raymond and Beverly Sackler Laboratory for Astrophysics, Leiden Observatory, University of Leiden, P.O. Box 9513, 2300 RA Leiden (Netherlands); Laffon, Carine; Parent, Philippe [Laboratoire de Chimie-Physique, Matiere et Rayonnement, Universite Pierre-et-Marie Curie (Paris 06) and CNRS (UMR 7614), 11 rue Pierre-et-Marie-Curie, 75231 Paris (France); Cuppen, Herma M., E-mail: emanuele.congiu@u-cergy.fr [Faculty of Science, Radboud University Nijmegen, IMM, P.O. Box 9010, NL 6500 GL Nijmegen (Netherlands)

2012-05-01

Icy dust grains in space act as catalytic surfaces onto which complex molecules form. These molecules are synthesized through exothermic reactions from precursor radicals and, mostly, hydrogen atom additions. Among the resulting products are species of biological relevance, such as hydroxylamine-NH{sub 2}OH-a precursor molecule in the formation of amino acids. In this Letter, laboratory experiments are described that demonstrate NH{sub 2}OH formation in interstellar ice analogs for astronomically relevant temperatures via successive hydrogenation reactions of solid nitric oxide (NO). Inclusion of the experimental results in an astrochemical gas-grain model proves the importance of a solid-state NO+H reaction channel as a starting point for prebiotic species in dark interstellar clouds and adds a new perspective to the way molecules of biological importance may form in space.

Methane excess in Arctic surface water-triggered by sea ice formation and melting.

Science.gov (United States)

Damm, E; Rudels, B; Schauer, U; Mau, S; Dieckmann, G

2015-11-10

Arctic amplification of global warming has led to increased summer sea ice retreat, which influences gas exchange between the Arctic Ocean and the atmosphere where sea ice previously acted as a physical barrier. Indeed, recently observed enhanced atmospheric methane concentrations in Arctic regions with fractional sea-ice cover point to unexpected feedbacks in cycling of methane. We report on methane excess in sea ice-influenced water masses in the interior Arctic Ocean and provide evidence that sea ice is a potential source. We show that methane release from sea ice into the ocean occurs via brine drainage during freezing and melting i.e. in winter and spring. In summer under a fractional sea ice cover, reduced turbulence restricts gas transfer, then seawater acts as buffer in which methane remains entrained. However, in autumn and winter surface convection initiates pronounced efflux of methane from the ice covered ocean to the atmosphere. Our results demonstrate that sea ice-sourced methane cycles seasonally between sea ice, sea-ice-influenced seawater and the atmosphere, while the deeper ocean remains decoupled. Freshening due to summer sea ice retreat will enhance this decoupling, which restricts the capacity of the deeper Arctic Ocean to act as a sink for this greenhouse gas.

Regions of open water and melting sea ice drive new particle formation in North East Greenland.

Science.gov (United States)

Dall Osto, M; Geels, C; Beddows, D C S; Boertmann, D; Lange, R; Nøjgaard, J K; Harrison, Roy M; Simo, R; Skov, H; Massling, A

2018-04-17

Atmospheric new particle formation (NPF) and growth significantly influences the indirect aerosol-cloud effect within the polar climate system. In this work, the aerosol population is categorised via cluster analysis of aerosol number size distributions (9-915 nm, 65 bins) taken at Villum Research Station, Station Nord (VRS) in North Greenland during a 7 year record (2010-2016). Data are clustered at daily averaged resolution; in total, we classified six categories, five of which clearly describe the ultrafine aerosol population, one of which is linked to nucleation events (up to 39% during summer). Air mass trajectory analyses tie these frequent nucleation events to biogenic precursors released by open water and melting sea ice regions. NPF events in the studied regions seem not to be related to bird colonies from coastal zones. Our results show a negative correlation (r = -0.89) between NPF events and sea ice extent, suggesting the impact of ultrafine Arctic aerosols is likely to increase in the future, given the likely increased sea ice melting. Understanding the composition and the sources of Arctic aerosols requires further integrated studies with joint multi-component ocean-atmosphere observation and modelling.

Proceedings of the 19. IAHR international symposium on ice : using new technology to understand water-ice interaction

International Nuclear Information System (INIS)

Jasek, M.; Andrishak, R.; Siddiqui, A.

2008-01-01

This conference provided a venue for scientists, engineers and researchers an opportunity to expand their knowledge of water-ice interactions with reference to water resources, river and coastal hydraulics, risk analysis, energy and the environment. The the theme of new technology falls into 3 basic groups, notably measurement and instrumentation; remote sensing; and numerical simulation. The thermal regime of rivers was discussed along with ice mechanics, ice hydraulics, ice structures and modelling ice phenomena. The titles of the sessions were: river ice, glaciers and climate change; freeze-up processes on rivers and oceans; river ice-structure interactions; numerical simulations in ice engineering; river-ice break-up and ice jam formation; ice measurement; Grasse River ice evaluation; evaluation of structural ice control alternatives; remote sensing; hydropower and dam decommissioning; mechanical behaviour of river ice, ice covered flow and thermal modelling; mathematical and computer model formulations for ice friction and sea ice; ice bergs and ice navigation; ice crushing processes; sea ice and shore/structure interactions; ice properties, testing and physical modelling; ice actions on compliant structures; oil spills in ice; desalination, ice thickness and climate change; and, sea ice ridges. The conference featured 123 presentations, of which 20 have been catalogued separately for inclusion in this database. refs., tabs., figs

FORMATION OF S-BEARING SPECIES BY VUV/EUV IRRADIATION OF H{sub 2}S-CONTAINING ICE MIXTURES: PHOTON ENERGY AND CARBON SOURCE EFFECTS

Energy Technology Data Exchange (ETDEWEB)

Chen, Y.-J.; Juang, K.-J.; Qiu, J.-M.; Chu, C.-C.; Yih, T.-S. [Department of Physics, National Central University, Jhongli City, Taoyuan County 32054, Taiwan (China); Nuevo, M. [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Jiménez-Escobar, A.; Muñoz Caro, G. M. [Centro de Astrobiología, INTA-CSIC, Torrejón de Ardoz, E-28850 Madrid (Spain); Wu, C.-Y. R. [Space Sciences Center and Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-1341 (United States); Fung, H.-S. [National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China); Ip, W.-H. [Graduate Institute of Astronomy, National Central University, Jhongli City, Taoyuan County 32049, Taiwan (China)

2015-01-10

Carbonyl sulfide (OCS) is a key molecule in astrobiology that acts as a catalyst in peptide synthesis by coupling amino acids. Experimental studies suggest that hydrogen sulfide (H{sub 2}S), a precursor of OCS, could be present in astrophysical environments. In the present study, we used a microwave-discharge hydrogen-flow lamp, simulating the interstellar UV field, and a monochromatic synchrotron light beam to irradiate CO:H{sub 2}S and CO{sub 2}:H{sub 2}S ice mixtures at 14 K with vacuum ultraviolet (VUV) or extreme ultraviolet (EUV) photons in order to study the effect of the photon energy and carbon source on the formation mechanisms and production yields of S-containing products (CS{sub 2}, OCS, SO{sub 2}, etc.). Results show that (1) the photo-induced OCS production efficiency in CO:H{sub 2}S ice mixtures is higher than that of CO{sub 2}:H{sub 2}S ice mixtures; (2) a lower concentration of H{sub 2}S enhances the production efficiency of OCS in both ice mixtures; and (3) the formation pathways of CS{sub 2} differ significantly upon VUV and EUV irradiations. Furthermore, CS{sub 2} was produced only after VUV photoprocessing of CO:H{sub 2}S ices, while the VUV-induced production of SO{sub 2} occurred only in CO{sub 2}:H{sub 2}S ice mixtures. More generally, the production yields of OCS, H{sub 2}S{sub 2}, and CS{sub 2} were studied as a function of the irradiation photon energy. Heavy S-bearing compounds were also observed using mass spectrometry during the warm-up of VUV/EUV-irradiated CO:H{sub 2}S ice mixtures. The presence of S-polymers in dust grains may account for the missing sulfur in dense clouds and circumstellar environments.

User's guide for ICE

International Nuclear Information System (INIS)

Fraley, S.K.

1976-07-01

ICE is a cross-section mixing code which will accept cross sections from an AMPX working library and produce mixed cross sections in the AMPX working library format, ANISN format, and the group-independent ANISN format. User input is in the free-form or fixed-form FIDO structure. The code is operable as a module in the AMPX system

Investigations on potential co-mutagenic effects of formaldehyde

Energy Technology Data Exchange (ETDEWEB)

Speit, Günter, E-mail: guenter.speit@uni-ulm.de; Linsenmeyer, Regina; Duong, Giang; Bausinger, Julia

2014-02-15

Highlights: • A549 cells were exposed to formaldehyde in combination with various mutagens. • Formaldehyde did not affect the induction and removal of DNA damage (comet assay). • Formaldehyde did not affect the induction of micronuclei by the mutagens tested. • The expression of the O{sup 6}-methylguanine-DNA methyltransferase was not affected. - Abstract: The genotoxicity and mutagenicity of formaldehyde (FA) has been well-characterized during the last years. Besides its known direct DNA-damaging and mutagenic activity in sufficiently exposed cells, FA at low concentrations might also enhance the mutagenic and carcinogenic effects of other environmental mutagens by interfering with the repair of DNA lesions induced by these mutagens. To further assess potential co-mutagenic effects of FA, we exposed A549 human lung cells to FA in combination with various mutagens and measured the induction and removal of DNA damage by the comet assay and the production of chromosomal mutations by the cytokinesis-block micronucleus assay (CBMN assay). The mutagens tested were ionizing radiation (IR), (±)-anti-B[a]P-7,8-dihydrodiol-9,10-epoxide (BPDE), N-nitroso-N-methylurea (methyl nitrosourea; MNU) and methyl methanesulfonate (MMS). FA (10–75 μM) did not enhance the genotoxic and mutagenic activity of these mutagens under the test conditions applied. FA alone and in combination with MNU or MMS did not affect the expression (mRNA level) of the gene of the O{sup 6}-methylguanine-DNA methyltransferase (MGMT) in A549 cells. The results of these experiments do not support the assumption that low FA concentrations might interfere with the repair of DNA damage induced by other mutagens.

High-resolution inversion of OMI formaldehyde columns over the Southeast US to infer isoprene emissions

Science.gov (United States)

Kaiser, J.; Zhu, L.; Travis, K.; Jacob, D.

2017-12-01

In the South East United States, biogenic isoprene fuels tropospheric ozone formation, and its oxidation products contribute significantly to organic aerosol. Bottom-up emission inventories rely on very limited isoprene emission and land-cover data, yielding uncertainties of a factor of 2 or more. Here, we use formaldehyde columns from the Ozone Monitoring Instrument in a high-resolution (0.25 x 0.325o) adjoint-based inversion to constrain isoprene emissions over the SE US during Aug-Sept of 2013. We find that the MEGANv2.1 inventory is biased high over most of the SE US. Our derived scaling factors show significant spatial variability, with the largest corrections applied to Louisiana and the Edwards Plateau in Texas. We test our inversion results against a comprehensive set of isoprene oxidation product observations from the NASA SEAC4RS flight campaign. The SEAC4RS data provides new confidence in the satellite retrievals and in mechanism linking isoprene oxidation to formaldehyde production. Finally, we relate the posterior scaling factors to the underlying land-type, and examine potential sources of observed biases.

Photochemical decomposition of Formaldehyde in solution.; Descomposicion fotoquimica de formaldehido en solucion.

Energy Technology Data Exchange (ETDEWEB)

Garrido Z, G

1995-10-01

In this work was studied the effect of ultraviolet radiation produced by a mercury low pressure lamp in solutions of formaldehyde. These solutions were exposed to ultraviolet rays at different times. In some of these series of solutions was added a photosensibilizer in order to obtain a high photodecomposition of formaldehyde. The techniques used for determine the products of the decomposition were the following: 1. In order to measure the residual formaldehyde and glioxal, the Hantzsch and 2,4-dinitrophenylhydrazine methods were used. 2. pH`s measurements of the solutions, before and after exposition. 3. Paper`s chromatography for determine presence of formed acids. 4. Acid-base tritiations for measure total acidification. We observed that when the time of exposition to UV rays was increased, a high photodecomposition of formaldehyde was formed and, besides, a greater quantity of another products. Of the reagents used like photosensibilizers, with the ruthenium reagent, the best results were obtained. (Author).

Volcanic terrain and the possible periglacial formation of "excess ice" at the mid-latitudes of Utopia Planitia, Mars

Science.gov (United States)

Soare, R. J.; Horgan, B.; Conway, S. J.; Souness, C.; El-Maarry, M. R.

2015-08-01

At the mid-latitudes of Utopia Planitia (UP), Mars, a suite of spatially-associated landforms exhibit geomorphological traits that, on Earth, would be consistent with periglacial processes and the possible freeze-thaw cycling of water. The suite comprises small-sized polygonally-patterned ground, polygon-junction and -margin pits, and scalloped, rimless depressions. Typically, the landforms incise a dark-toned terrain that is thought to be ice-rich. Here, we investigate the dark-toned terrain by using high resolution images from the HiRISE as well as near-infrared spectral-data from the OMEGA and CRISM. The terrain displays erosional characteristics consistent with a sedimentary nature and near-infrared spectra characterised by a blue slope similar to that of weathered basaltic-tephra. We also describe volcanic terrain that is dark-toned and periglacially-modified in the Kamchatka mountain-range of eastern Russia. The terrain is characterised by weathered tephra inter-bedded with snow, ice-wedge polygons and near-surface excess ice. The excess ice forms in the pore space of the tephra as the result of snow-melt infiltration and, subsequently, in-situ freezing. Based on this possible analogue, we construct a three-stage mechanism that explains the possible ice-enrichment of a broad expanse of dark-toned terrain at the mid-latitudes of UP: (1) the dark-toned terrain accumulates and forms via the regional deposition of sediments sourced from explosive volcanism; (2) the volcanic sediments are blanketed by atmospherically-precipitated (H2O) snow, ice or an admixture of the two, either concurrent with the volcanic-events or between discrete events; and, (3) under the influence of high obliquity or explosive volcanism, boundary conditions tolerant of thaw evolve and this, in turn, permits the migration, cycling and eventual formation of excess ice in the volcanic sediments. Over time, and through episodic iterations of this scenario, excess ice forms to decametres of

Ice cloud processing of ultra-viscous/glassy aerosol particles leads to enhanced ice nucleation ability

Directory of Open Access Journals (Sweden)

R. Wagner

2012-09-01

Full Text Available The ice nucleation potential of airborne glassy aqueous aerosol particles has been investigated by controlled expansion cooling cycles in the AIDA aerosol and cloud chamber of the Karlsruhe Institute of Technology at temperatures between 247 and 216 K. Four different solutes were used as proxies for oxygenated organic matter found in the atmosphere: raffinose, 4-hydroxy-3-methoxy-DL-mandelic acid (HMMA, levoglucosan, and a multi-component mixture of raffinose with five dicarboxylic acids and ammonium sulphate. Similar to previous experiments with citric acid aerosols, all particles were found to nucleate ice heterogeneously before reaching the homogeneous freezing threshold provided that the freezing cycles were started well below the respective glass transition temperatures of the compounds; this is discussed in detail in a separate article. In this contribution, we identify a further mechanism by which glassy aerosols can promote ice nucleation below the homogeneous freezing limit. If the glassy aerosol particles are probed in freezing cycles started only a few degrees below their respective glass transition temperatures, they enter the liquid regime of the state diagram upon increasing relative humidity (moisture-induced glass-to-liquid transition before being able to act as heterogeneous ice nuclei. Ice formation then only occurs by homogeneous freezing at elevated supersaturation levels. When ice forms the remaining solution freeze concentrates and re-vitrifies. If these ice cloud processed glassy aerosol particles are then probed in a second freezing cycle at the same temperature, they catalyse ice formation at a supersaturation threshold between 5 and 30% with respect to ice. By analogy with the enhanced ice nucleation ability of insoluble ice nuclei like mineral dusts after they nucleate ice once, we refer to this phenomenon as pre-activation. We propose a number of possible explanations for why glassy aerosol particles that have re

Soft-sediment deformation structures from an ice-marginal storm-tide interactive system, Permo-Carboniferous Talchir Formation, Talchir Coalbasin, India

Science.gov (United States)

Bhattacharya, H. N.; Bhattacharya, Biplab

2010-01-01

Permo-Carboniferous Talchir Formation, Talchir Coalbasin, India, records sedimentation during a phase of climatic amelioration in an ice-marginal storm-affected shelf. Evidences of subtidal processes are preserved only under thick mud drapes deposited during waning storm phases. Various soft-sediment deformation structures in some sandstone/siltstone-mudstone interbeds, like syn-sedimentary faults, deformed laminations, sand-silt flows, convolute laminations and various flame structures, suggest liquefaction and fluidization of the beds due to passage of syn-depositional seismic shocks. In the Late Paleozoic ice-marginal shelf, such earthquake tremors could be generated by crustal movements in response to glacioisostatic adjustments of the basin floor.

A Simple Approach to Distinguish Classic and Formaldehyde-Free Tannin Based Rigid Foams by ATR FT-IR

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Gianluca Tondi

2015-01-01

Full Text Available Tannin based rigid foams (TBRFs have been produced with formaldehyde since 1994. Only recently several methods have been developed in order to produce these foams without using formaldehyde. TBRFs with and without formaldehyde are visually indistinguishable; therefore a method for determining the differences between these foams had to be found. The attenuated total reflectance infrared spectroscopy (ATR FT-IR investigation of the TBRFs presented in this paper allowed discrimination between the formaldehyde-containing (classic and formaldehyde-free TBRFs. The spectra of the formaldehyde-free TBRFs, indeed, present decreased band intensity related to the C–O stretching vibration of (i the methylol groups and (ii the furanic rings. This evidence served to prove the chemical difference between the two TBRFs and explained the slightly higher mechanical properties measured for the classic TBRFs.

Regulation characteristics of oxide generation and formaldehyde removal by using volume DBD reactor

Science.gov (United States)

Bingyan, CHEN; Xiangxiang, GAO; Ke, CHEN; Changyu, LIU; Qinshu, LI; Wei, SU; Yongfeng, JIANG; Xiang, HE; Changping, ZHU; Juntao, FEI

2018-02-01

Discharge plasmas in air can be accompanied by ultraviolet (UV) radiation and electron impact, which can produce large numbers of reactive species such as hydroxyl radical (OH·), oxygen radical (O·), ozone (O3), and nitrogen oxides (NO x ), etc. The composition and dosage of reactive species usually play an important role in the case of volatile organic compounds (VOCs) treatment with the discharge plasmas. In this paper, we propose a volume discharge setup used to purify formaldehyde in air, which is configured by a plate-to-plate dielectric barrier discharge (DBD) channel and excited by an AC high voltage source. The results show that the relative spectral-intensity from DBD cell without formaldehyde is stronger than the case with formaldehyde. The energy efficiency ratios (EERs) of both oxides yield and formaldehyde removal can be regulated by the gas flow velocity in DBD channel, and the most desirable processing effect is the gas flow velocity within the range from 2.50 to 3.33 m s-1. Moreover, the EERs of both the generated dosages of oxides (O3 and NO2) and the amount of removed formaldehyde can also be regulated by both of the applied voltage and power density loaded on the DBD cell. Additionally, the EERs of both oxides generation and formaldehyde removal present as a function of normal distribution with increasing the applied power density, and the peak of the function is appeared in the range from 273.5 to 400.0 W l-1. This work clearly demonstrates the regulation characteristic of both the formaldehyde removal and oxides yield by using volume DBD, and it is helpful in the applications of VOCs removal by using discharge plasma.

Determination of carbonyl compounds (acetaldehyde and formaldehyde in polyethylene terephthalate containers designated for water conservation

Directory of Open Access Journals (Sweden)

Redžepović Azra S.

2012-01-01

Full Text Available Polyethylene terephthalate (PET has in the last several years become the main packaging material for many food products, particularly carbonated beverages and bottled water, as well as for products of chemical industry (packaging of various hygiene maintenance agents, pesticides, solvents, etc.. The strength and permeability properties of PET are very good for packaging of beverages, its resistance to chemicals is high and it has a high degree of transparency. Acetaldehyde and formaldehyde are formed during the thermoforming of PET containers. After cooling, acetaldehyde and formaldehyde remain trapped in the walls of a PET bottle and may migrate into the water after filling and storage. Since there are no migration tests in Serbia prescribed for the determination of acetaldehyde and formaldehyde, the purpose of the paper is to test the quantitative contents of carbonyl compounds (acetaldehyde and formaldehyde in PET containers of different volumes, made by various manufacturers of bottled mineral carbonated and noncarbonated water, and exposed to different temperatures. In this study, the migration of acetaldehyde and formaldehyde from PET bottles into mineral carbonated and noncarbonated water was determined by high performance liquid chromatography. Taking into consideration that formaldehyde and acetaldehyde have no UV active or fluorescent group, the chromatography shall be preceded by derivatization in a closed system (due to a low boiling point of acetaldehyde and formaldehyde, which shall transform carbonyl compounds into UV active compounds.

Novel silicone-based polymer containing active methylene designed for the removal of indoor formaldehyde

Energy Technology Data Exchange (ETDEWEB)

Niu, Song, E-mail: niusong84@163.com; Yan, Hongxia, E-mail: hongxiayan@nwpu.edu.cn

2015-04-28

Highlights: • A novel silicone-based polymer with active methylene was explored. • Surface tension of liquid paints could be lowered using the polymer. • The polymer was easy to migrate toward the air-coating interface. • Free HCHO could effectively be removed using the polymer. • A lights on HCHO reduction without complicated preparation procedure was shielded. - Abstract: Indoor air pollution is caused inevitably due to complicated home decoration, in which formaldehyde is one of the most typical pollutants. It will be a convenient, economical and effective strategy to remove indoor formaldehyde if imparting a feature of formaldehyde removal to decorative coatings. We have successfully explored a novel silicone-based polymer containing active methylene used as a formaldehyde absorbent in coatings via a straightforward transesterification process using inexpensive and easily available chemicals. The polymer has been characterized by {sup 13}C NMR, FTIR, GC and GPC. Formaldehyde removal capacity of the coating films containing different contents of the polymer has been investigated. The results indicated that coatings incorporating 4 wt% of the polymer could make the coating films exhibit significant improvement on formaldehyde removal including purificatory performance (>85%) and durability of purificatory effect (>60%), compared to those consisting of absorbents without any silicon, and improve yellowing resistance performance, while other properties, such as gloss, adhesion, pencil hardness, flexibility and impact resistance, were kept almost unaffected. The chemical absorption process of the silicone-based polymer filled in interior decorative coatings is demonstrated as a promising technology to purify indoor formaldehyde and thus can reduce the harm to individuals.

Probing Individual Ice Nucleation Events with Environmental Scanning Electron Microscopy

Science.gov (United States)

Wang, Bingbing; China, Swarup; Knopf, Daniel; Gilles, Mary; Laskin, Alexander

2016-04-01

Heterogeneous ice nucleation is one of the processes of critical relevance to a range of topics in the fundamental and the applied science and technologies. Heterogeneous ice nucleation initiated by particles proceeds where microscopic properties of particle surfaces essentially control nucleation mechanisms. Ice nucleation in the atmosphere on particles governs the formation of ice and mixed phase clouds, which in turn influence the Earth's radiative budget and climate. Heterogeneous ice nucleation is still insufficiently understood and poses significant challenges in predictive understanding of climate change. We present a novel microscopy platform allowing observation of individual ice nucleation events at temperature range of 193-273 K and relative humidity relevant for ice formation in the atmospheric clouds. The approach utilizes a home built novel ice nucleation cell interfaced with Environmental Scanning Electron Microscope (IN-ESEM system). The IN-ESEM system is applied for direct observation of individual ice formation events, determining ice nucleation mechanisms, freezing temperatures, and relative humidity onsets. Reported microanalysis of the ice nucleating particles (INP) include elemental composition detected by the energy dispersed analysis of X-rays (EDX), and advanced speciation of the organic content in particles using scanning transmission x-ray microscopy with near edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). The performance of the IN-ESEM system is validated through a set of experiments with kaolinite particles with known ice nucleation propensity. We demonstrate an application of the IN-ESEM system to identify and characterize individual INP within a complex mixture of ambient particles.

Periodic fluctuations in deep water formation due to sea ice

Science.gov (United States)

Saha, R.

2012-12-01

During the last ice age, several abrupt warming events took place, known as Dansgaard-Oeschger (D-O) events. Their effects were felt globally, although the North Atlantic experienced the largest temperature increase. The leading hypothesis to explain their occurrence postulates that the warming was caused by abrupt disruptions of the North Atlantic Current due to meltwater discharge from destabilized ice sheets (Heinrich events). However, the number of warming events outnumber the those of ice-sheet collapse. Thus, the majority of D-O events are not attributed to surface freshwater anomalies, and the underlying mechanism behind their occurrence remain unexplained. Using a simple dynamical model of sea ice and an overturning circulation, I show the existence of self-sustained relaxation oscillations in the overturning circulation. The insulating effect of sea ice is shown to paradoxically lead to a net loss of heat from the top layer of the polar ocean when sea ice retreats. Repeated heat loss results in a denser top layer and a destabilized water column, which triggers convection. The convective state pulls the system out of its preferred mode of circulation, setting up relaxation oscillations. The period of oscillations in this case is linked to the geometry of the ocean basin, if solar forcing is assumed to remain constant. If appropriate glacial freshwater forcing is applied to the model, a pattern of oscillation is produced that bears remarkable similarity to the observed fluctuations in North Atlantic climate between 50,000 and 30,000 years before present.; Comparison of NGRIP δ 18-O (proxy for near surface air temperature) between 50,000 and 30,000 years before present, showing Bond cycles (left) with the model output when forced with appropriate glacial freshwater forcing (right).

High-Throughput Platform for Synthesis of Melamine-Formaldehyde Microcapsules.

Science.gov (United States)

Çakir, Seda; Bauters, Erwin; Rivero, Guadalupe; Parasote, Tom; Paul, Johan; Du Prez, Filip E

2017-07-10

The synthesis of microcapsules via in situ polymerization is a labor-intensive and time-consuming process, where many composition and process factors affect the microcapsule formation and its morphology. Herein, we report a novel combinatorial technique for the preparation of melamine-formaldehyde microcapsules, using a custom-made and automated high-throughput platform (HTP). After performing validation experiments for ensuring the accuracy and reproducibility of the novel platform, a design of experiment study was performed. The influence of different encapsulation parameters was investigated, such as the effect of the surfactant, surfactant type, surfactant concentration and core/shell ratio. As a result, this HTP-platform is suitable to be used for the synthesis of different types of microcapsules in an automated and controlled way, allowing the screening of different reaction parameters in a shorter time compared to the manual synthetic techniques.

Cloud condensation nuclei and ice nucleation activity of hydrophobic and hydrophilic soot particles.

Science.gov (United States)

Koehler, Kirsten A; DeMott, Paul J; Kreidenweis, Sonia M; Popovicheva, Olga B; Petters, Markus D; Carrico, Christian M; Kireeva, Elena D; Khokhlova, Tatiana D; Shonija, Natalia K

2009-09-28

Cloud condensation nuclei (CCN) activity and ice nucleation behavior (for temperaturesnucleation experiments below -40 degrees C, AEC particles nucleated ice near the expected condition for homogeneous freezing of water from aqueous solutions. In contrast, GTS, TS, and TC1 required relative humidity well in excess of water saturation at -40 degrees C for ice formation. GTS particles required water supersaturation conditions for ice activation even at -51 degrees C. At -51 to -57 degrees C, ice formation in particles with electrical mobility diameter of 200 nm occurred in up to 1 in 1000 TS and TC1 particles, and 1 in 100 TOS particles, at relative humidities below those required for homogeneous freezing in aqueous solutions. Our results suggest that heterogeneous ice nucleation is favored in cirrus conditions on oxidized hydrophilic soot of intermediate polarity. Simple considerations suggest that the impact of hydrophilic soot particles on cirrus cloud formation would be most likely in regions of elevated atmospheric soot number concentrations. The ice formation properties of AEC soot are reasonably consistent with present understanding of the conditions required for aircraft contrail formation and the proportion of soot expected to nucleate under such conditions.

Investigation of formaldehyde pollution of tap water and rain water using a novel visual colorimetry.

Science.gov (United States)

Murai, K; Okano, M; Kuramitz, H; Hata, N; Kawakami, T; Taguchi, S

2008-01-01

The pollution of tap water and rain water with formaldehyde in Toyama Pref., Japan was investigated by means of a simple, rapid and cost-effective visual colorimetry developed by us. The levels of formaldehyde in three tap waters from different sources of dams on mountainside and a well-water pumped in urban area in Toyama Pref. were lower than 0.01 mg L(-1) that was the detection limit of the colorimetry. On the other hand, rain waters were seriously polluted with formaldehyde. Rain waters were sampled from three different sites (urban area, top of hill and industrial area) in Toyama Pref. from autumn to winter in 2006. The levels of formaldehyde in the rain waters ranged from 0.07 to 0.30 mg L(-1). The analytical results by the visual colorimetry were in good agreement with those obtained by GC-MS method. It was confirmed that the colorimetry is excellent for practical use for the determination of formaldehyde. It must be concerned about the pollution of rainwater with formaldehyde, when rain water is applied for tap water and miscellaneous purpose. Copyright IWA Publishing 2008.

Cross-Aldol condensation of isobutyraldehyde and formaldehyde using phase transfer catalyst

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Azhar Hashmi

2016-09-01

Full Text Available The hydroxypivaldehyde (HPA precursor intermediate for the synthesis of neopentyl glycol (NPG is prepared by novel cross Aldol condensation of isobutyraldehyde and formaldehyde at 20 °C using benzyltrimethylammonium hydroxide, a basic phase transfer catalyst. A feed mole ratio of 1.1:1.0:0.04 (isobutyraldehyde:formaldehyde:benzyltrimethylammonium hydroxide afforded hydroxypivaldehyde as white solid in almost quantitative yield with ∼100% selectivity.

Cross-Aldol condensation of isobutyraldehyde and formaldehyde using phase transfer catalyst

OpenAIRE

Azhar Hashmi

2016-01-01

The hydroxypivaldehyde (HPA) precursor intermediate for the synthesis of neopentyl glycol (NPG) is prepared by novel cross Aldol condensation of isobutyraldehyde and formaldehyde at 20 °C using benzyltrimethylammonium hydroxide, a basic phase transfer catalyst. A feed mole ratio of 1.1:1.0:0.04 (isobutyraldehyde:formaldehyde:benzyltrimethylammonium hydroxide) afforded hydroxypivaldehyde as white solid in almost quantitative yield with ∼100% selectivity.

Formaldehyde emission from particleboard and plywood paneling : measurement, mechanism, and product standards

Science.gov (United States)

George E. Myers

1983-01-01

A number of commercial panel products, primarily particleboard and hardwood plywood, were tested for their formaldehyde emission behavior using desiccator, perforator, and dynamic chamber methods. The results were analyzed in terms of the source of formaldehyde observed in the tests (free vs. hydrolytically produced) and the potential utility of the testa as product...

Gypsum crystals observed in experimental and natural sea ice

Science.gov (United States)

Geilfus, N.-X.; Galley, R. J.; Cooper, M.; Halden, N.; Hare, A.; Wang, F.; Søgaard, D. H.; Rysgaard, S.

2013-12-01

gypsum has been predicted to precipitate in sea ice, it has never been observed. Here we provide the first report on gypsum precipitation in both experimental and natural sea ice. Crystals were identified by X-ray diffraction analysis. Based on their apparent distinguishing characteristics, the gypsum crystals were identified as being authigenic. The FREeZing CHEMistry (FREZCHEM) model results support our observations of both gypsum and ikaite precipitation at typical in situ sea ice temperatures and confirms the "Gitterman pathway" where gypsum is predicted to precipitate. The occurrence of authigenic gypsum in sea ice during its formation represents a new observation of precipitate formation and potential marine deposition in polar seas.

Angle-resolved photoelectron spectroscopy of formaldehyde and methanol

Science.gov (United States)

Keller, P. R.; Taylor, J. W.; Grimm, F. A.; Carlson, Thomas A.

1984-10-01

Angle-resolved photoelectron spectroscopy was employed to obtain the angular distribution parameter, β, for the valence orbitals (IP < 21.1 eV) of formaldehyde and methanol over the 10-30 eV photon energy range using dispersed polarized synchrotron radiation as the excitation source. It was found that the energy dependence of β in the photoelectron energy range between 2 and 10 eV can be related to the molecular-orbital type from which ionization occurs. This generalized energy behavior is discussed with regard to earlier energy-dependence studies on molecules of different orbital character. Evidence is presented for the presence of resonance photoionization phenomena in formaldehyde in agreement with theoretical cross-section calculations.

Enzymatic synthesis of C-11 formaldehyde: concise communication

International Nuclear Information System (INIS)

Slegers, G.; Lambrecht, R.H.D.; Vandewalle, T.; Meulewaeter, L.; Vandecasteele, C.

1984-01-01

An enzymatic synthesis of C-11 formaldehyde from C-11 methanol is presented, with immobilized alcohol oxidase and catalase: a rapid, simple procedure, with a high and reproducible yield. Carbon-11 methanol is oxidized to C-11 formaldehyde by passage over a column on which the enzymes alcohol oxidase and catalase are immobilized. The catalase increases reaction velocity by recycling the oxygen, and prevents destruction of the alcohol oxidase by eliminating the excess of hydrogen peroxide. The yield of the enzyme-catalyzed oxidation was 80-95%. A specific activity of 400-450 mCi/μmole was obtained at EOB + 20 min. Various immobilization techniques and the optimal reaction conditions of the immobilized enzymes are investigated

Reversible and formaldehyde-mediated covalent binding of a bis-amino mitoxantrone analogue to DNA.

Science.gov (United States)

Konda, Shyam K; Kelso, Celine; Pumuye, Paul P; Medan, Jelena; Sleebs, Brad E; Cutts, Suzanne M; Phillips, Don R; Collins, J Grant

2016-05-18

The ability of a bis-amino mitoxantrone anticancer drug (named WEHI-150) to form covalent adducts with DNA, after activation by formaldehyde, has been studied by electrospray ionisation mass spectrometry and HPLC. Mass spectrometry results showed that WEHI-150 could form covalent adducts with d(ACGCGCGT)2 that contained one, two or three covalent links to the octanucleotide, whereas the control drugs (daunorubicin and the anthracenediones mitoxantrone and pixantrone) only formed adducts with one covalent link to the octanucleotide. HPLC was used to examine the extent of covalent bond formation of WEHI-150 with d(CGCGCG)2 and d(CG(5Me)CGCG)2. Incubation of WEHI-150 with d(CG(5Me)CGCG)2 in the presence of formaldehyde resulted in the formation of significantly greater amounts of covalent adducts than was observed with d(CGCGCG)2. In order to understand the observed increase of covalent adducts with d(CG(5Me)CGCG)2, an NMR study of the reversible interaction of WEHI-150 at both CpG and (5Me)CpG sites was undertaken. Intermolecular NOEs were observed in the NOESY spectra of d(ACGGCCGT)2 with added WEHI-150 that indicated that the drug selectively intercalated at the CpG sites and from the major groove. In particular, NOEs were observed from the WEHI-150 H2,3 protons to the H1' protons of G3 and G7 and from the H6,7 protons to the H5 protons of C2 and C6. By contrast, intermolecular NOEs were observed between the WEHI-150 H2,3 protons to the H2'' proton of the (5Me)C3 in d(CG(5Me)CGCG)2, and between the drug aliphatic protons and the H1' proton of G4. This demonstrated that WEHI-150 preferentially intercalates at (5Me)CpG sites, compared to CpG sequences, and predominantly via the minor groove at the (5Me)CpG site. The results of this study demonstrate that WEHI-150 is likely to form interstrand DNA cross-links, upon activation by formaldehyde, and consequently exhibit greater cytotoxicity than other current anthracenedione drugs.

Large sea ice outflow into the Nares Strait in 2007

DEFF Research Database (Denmark)

Kwok, R.; Pedersen, L.T.; Gudmandsen, Preben

2010-01-01

Sea ice flux through the Nares Strait is most active during the fall and early winter, ceases in mid- to late winter after the formation of ice arches along the strait, and re-commences after breakup in summer. In 2007, ice arches failed to form. This resulted in the highest outflow of Arctic sea...... at Fram Strait. Clearly, the ice arches control Arctic sea ice outflow. The duration of unobstructed flow explains more than 84% of the variance in the annual area flux. In our record, seasonal stoppages are always associated with the formation of an arch near the same location in the southern Kane Basin...... ice in the 13-year record between 1997 and 2009. The 2007 area and volume outflows of 87 x 10(3) km(2) and 254 km(3) are more than twice their 13-year means. This contributes to the recent loss of the thick, multiyear Arctic sea ice and represents similar to 10% of our estimates of the mean ice export...

Skating on slippery ice

Directory of Open Access Journals (Sweden)

J. M. J. van Leeuwen

2017-12-01

Full Text Available The friction of a stationary moving skate on smooth ice is investigated, in particular in relation to the formation of a thin layer of water between skate and ice. It is found that the combination of ploughing and sliding gives a friction force that is rather insensitive for parameters such as velocity and temperature. The weak dependence originates from the pressure adjustment inside the water layer. For instance, high velocities, which would give rise to high friction, also lead to large pressures, which, in turn, decrease the contact zone and so lower the friction. The theory is a combination and completion of two existing but conflicting theories on the formation of the water layer.

Formaldehyde-related clinical symptoms reported by medical students during gross anatomy cadaver dissection

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Łukasz Pietrzyk

2016-09-01

Full Text Available Introduction . Formaldehyde is a noxious gas used as a tissue preservative of cadavers in autopsy rooms. Therefore, exposure to higher concentrations applies particularly to laboratory staff, anatomists and medical students. Prolonged exposure to formaldehyde is associated with clinical complications. Objective. To assess whether exposure to repeated inhalation of low concentrations of formaldehyde (FA experienced during a gross anatomy course triggers subjective clinical symptoms in medical students. Material and methods . All 198 first-year medical students of the Medical University of Lublin, Poland (28% with allergy history and 72% without allergy history; 69% male and 31% female responded to a questionnaire concerning their subjective FA-related clinical symptoms. Differences in proportions of experienced symptoms between allergic vs. nonallergic, and female vs. males were compared by the Mann-Whitney U test. Results . Even though formaldehyde concentrations in the gross anatomy laboratory were relatively low (0.47–0.57 mg/m3, medical students experienced various reactions (lacrimation in 85.9%, red eyes, dry and itchy eyes, runny nose, sneezing, and headache in > 50% of students, cough in 44%, and dry throat or throat irritation in 42% of students. Among students with a history of allergy, eye, nose, skin and respiratory system symptoms occurred more frequently in comparison to nonallergic students. Female individuals demonstrated higher sensitivity to FA exposure. Conclusions . Exposure to formaldehyde may result in development of clinical symptoms in medical students. Particularly unpleasant symptoms may be experienced by individuals with allergy history. It is necessary to decrease formaldehyde concentrations in the anatomy dissection laboratory.

REGULARITIES OF CONGELATION ICE DEVELOPMENT IN SUBGLACIAL LAKE VOSTOK

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V. Ya. Lipenkov

2012-01-01

Full Text Available Petrographic studies performed on the continuous basis along the two ice cores obtained from holes 5G-1 and 5G-2 at Vostok Station has allowed to characterize with great details the evolution of the ice texture and fabric in the 232-m thick stratum of accreted ice formed from theLakeVostokwater. Conventionally the whole thickness of accreted ice is divided into two strata: lake ice 1 and lake ice 2. Lake ice 1 (3537–3618 m, formed in the sallow strait50 kmupstream of Vostok, is characterized by presence of disseminated mineral inclusions of Lake Vostok sediments, as well as of «water pockets» that represent frozen water inclusions trapped during the ice accretion. The latter constitute less than 1% of the total ice volume, their mean size is about0.5 cm. Gases trapped by «water pockets» during ice formation transform into crystalline inclusions of mixed gas hydrates. Accretion of lake ice 2 (3618–3769 m proceeds in the deep part of the lake at a very small rate that does not assume trapping of liquid water inclusions and gases.Both strata of accreted ice are formed by orthotropic crystal growth from pure water. The main tendency in the evolution of accreted ice texture is growth of the mean crystal size with depth as the lake ice becomes younger towards the ice-water interface. The high-amplitude variations of crystal size and orientation observed around this general trend are shown to be linked with temporal and spatial variability of the supercooled melt-water flux from the northern part of the lake towards the ice formation site. The presence of supercooled water at the crystallization front supports persistent preferable growth of ice crystals with sub-horizontally oriented c-axes. The lack of supercooled water in turn support persistent growth of ice crystals with vertical or inclined with respect to the crystallization front c-axis orientation. It means that each of these preferred fabric orientations could serve as an indicator of

The role of ice dynamics in shaping vegetation in flowing waters.

Science.gov (United States)

Lind, Lovisa; Nilsson, Christer; Polvi, Lina E; Weber, Christine

2014-11-01

Ice dynamics is an important factor affecting vegetation in high-altitude and high-latitude streams and rivers. During the last few decades, knowledge about ice in streams and rivers has increased significantly and a respectable body of literature is now available. Here we review the literature on how ice dynamics influence riparian and aquatic vegetation. Traditionally, plant ecologists have focused their studies on the summer period, largely ignoring the fact that processes during winter also impact vegetation dynamics. For example, the freeze-up period in early winter may result in extensive formation of underwater ice that can restructure the channel, obstruct flow, and cause flooding and thus formation of more ice. In midwinter, slow-flowing reaches develop a surface-ice cover that accumulates snow, protecting habitats under the ice from formation of underwater ice but also reducing underwater light, thus suppressing photosynthesis. Towards the end of winter, ice breaks up and moves downstream. During this transport, ice floes can jam up and cause floods and major erosion. The magnitudes of the floods and their erosive power mainly depend on the size of the watercourse, also resulting in different degrees of disturbance to the vegetation. Vegetation responds both physically and physiologically to ice dynamics. Physical action involves the erosive force of moving ice and damage caused by ground frost, whereas physiological effects - mostly cell damage - happen as a result of plants freezing into the ice. On a community level, large magnitudes of ice dynamics seem to favour species richness, but can be detrimental for individual plants. Human impacts, such as flow regulation, channelisation, agriculturalisation and water pollution have modified ice dynamics; further changes are expected as a result of current and predicted future climate change. Human impacts and climate change can both favour and disfavour riverine vegetation dynamics. Restoration of streams

A new system to reduce formaldehyde levels improves safety conditions during gross veterinary anatomy learning.

Science.gov (United States)

Nacher, Víctor; Llombart, Cristina; Carretero, Ana; Navarro, Marc; Ysern, Pere; Calero, Sebastián; Fígols, Enric; Ruberte, Jesús

2007-01-01

Dissection is a very useful method of learning veterinary anatomy. However, formaldehyde, which is widely used to preserve cadavers, is an irritant, and it has recently been classified as a carcinogen. In 1997, the Instituto Nacional de Seguridad e Higiene en el Trabajo [National Institute of Workplace Security and Hygiene] found that the levels of formaldehyde in our dissection room were above the threshold limit values. Unfortunately, no optimal substitute for formaldehyde is currently available. Therefore, we designed a new ventilation system that combines slow propulsion of fresh air from above the dissection table and rapid aspiration of polluted air from the perimeter. Formaldehyde measurements performed in 2004, after the introduction of this new system into our dissection laboratory, showed a dramatic reduction (about tenfold, or 0.03 ppm). A suitable propelling/aspirating air system successfully reduces the concentration of formaldehyde in the dissection room, significantly improving safety conditions for students, instructors, and technical staff during gross anatomy learning.

Constraints on the formation and properties of a Martian lobate debris apron: Insights from high-resolution topography, SHARAD radar data, and a numerical ice flow model

Science.gov (United States)

Parsons, Reid; Holt, John

2016-03-01

Lobate debris aprons (LDAs) are midlatitude deposits of debris-covered ice formed during one or more periods of glaciation during the Amazonian period. However, little is known about the climate conditions that led to LDA formation. We explore a hypothesis in which a single, extended period of precipitation of ice on the steep slopes of Euripus Mons (45°S, 105°E—east of the Hellas Basin) produced a flowing ice deposit which was protected from subsequent ablation to produce the LDA found at this location. We test this hypothesis with a numerical ice flow model using an ice rheology based on low-temperature ice deformation experiments. The model simulates ice accumulation and flow for the northern and southern lobes of the Euripus Mons LDA using basal topography constrained by data from the Shallow Radar (SHARAD) and a range of ice viscosities (determined by ice temperature and ice grain size). Simulations for the northern lobe of the Euripus LDA produce good fits to the surface topography. Assuming an LDA age of ˜60 Myr and an expected temperature range of 200 to 204 K (for various obliquities) gives an ice grain size of ≈2 mm. Simulations of the southern section produce poor fits to surface topography and result in much faster flow timescales unless multiple ice deposition events or higher ice viscosities are considered.

The time-dependence of the defective nature of ice Ic (cubic ice) and its implications for atmospheric science

Science.gov (United States)

Sippel, Christian; Koza, Michael M.; Hansen, Thomas C.; Kuhs, Werner F.

2010-05-01

The possible atmospheric implication of ice Ic (cubic ice) has already been suggested some time ago in the context of snow crystal formation [1]. New findings from air-borne measurements in cirrus clouds and contrails have put ice Ic into the focus of interest to understand the so-called "supersaturation puzzle" [2,3,4]. Our recent microstructural work on ice Ic [5,6] appears to be highly relevant in this context. We have found that ice Ic is characterized by a complex stacking fault pattern, which changes as a function of temperature as well as time. Indeed, from our own [7] and other group's work [8] one knows that (in contrast to earlier believe) ice Ic can form up to temperatures at least as high as 240K - thus in the relevant range for cirrus clouds. We have good preliminary evidence that the "cubicity" (which can be related to stacking fault probabilities) as well as the particle size of ice Ic are the relevant parameters for this correlation. The "cubicity" of stacking faulty ice Ic (established by diffraction) correlates nicely with the increased supersaturation at decreasing temperatures observed in cirrus clouds and contrails, a fact, which may be considered as further evidence for the presence of ice Ic. Recently, we have studied the time-dependency of the changes in both "cubicity" and particle size at various temperatures of relevance for cirrus clouds and contrails by in-situ neutron powder diffraction. The timescales over which changes occur (several to many hours) are similar to the life-time of cirrus clouds and contrails and suggest that the supersaturation situation may change within this time span in the natural environment too. Some accompanying results obtained by cryo-SEM (scanning electron microscopy) work will also be presented and suggest that stacking-faulty ice Ic has kinky surfaces providing many more active centres for heterogeneous reactions on the surface than in the usually assumed stable hexagonal form of ice Ih with its rather

FABRICATION AND PROPERTIES OVERCOATED RESORCINOL-FORMALDEHYDE SHELLS FOR OMEGA EXPERIMENTS

International Nuclear Information System (INIS)

NIKROO, A; CZECHOWICZ, D; PAGUIO, R; GREENWOOD, A.L; TAKAGI, M.

2003-09-01

OAK-B135 New high gain designs for direct drive ignition on NIF require foam shells. Scaled down versions of these designs are needed for near term experiments on the OMEGA laser facility at the Laboratory Laser Energetics (LLE). These shells need to be about 1 mm in diameter and 50-100 (micro)m wall thickness and densities of 100-250 mg/cc. In addition, a full density permeation seal needs to be deposited for retention of the fill gas at room temperature or the ice at cryogenic temperatures. They have fabricated such shells using Resorcinol-formaldehyde (R/F) as the selected foam material due to its transparency in the optical region. Extensive characterization of the wall uniformity of these shells has been performed. The foam shells have ∼ 5%-6% non-concentricities on the average. A full density permeation seal has been deposited on the R/F shells using two different techniques. In the first technique R/F shells are coated directly with plasma polymer to thicknesses of 3-4 (micro)m. In the second technique, R/F shells are coated with polyvinylphenol, using a chemical interfacial polymerization technique. Data on surface finish and gas retention for R/F shells coated by both methods are provided

Nuclear spin conversion in formaldehyde

OpenAIRE

Chapovsky, Pavel L.

2000-01-01

Theoretical model of the nuclear spin conversion in formaldehyde (H2CO) has been developed. The conversion is governed by the intramolecular spin-rotation mixing of molecular ortho and para states. The rate of conversion has been found equal 1.4*10^{-4}~1/s*Torr. Temperature dependence of the spin conversion has been predicted to be weak in the wide temperature range T=200-900 K.

An integrated approach to the remote sensing of floating ice

Science.gov (United States)

Campbell, W. J.; Ramseier, R. O.; Weeks, W. F.; Gloersen, P.

1976-01-01

Review article on remote sensing applications to glaciology. Ice parameters sensed include: ice cover vs open water, ice thickness, distribution and morphology of ice formations, vertical resolution of ice thickness, ice salinity (percolation and drainage of brine; flushing of ice body with fresh water), first-year ice and multiyear ice, ice growth rate and surface heat flux, divergence of ice packs, snow cover masking ice, behavior of ice shelves, icebergs, lake ice and river ice; time changes. Sensing techniques discussed include: satellite photographic surveys, thermal IR, passive and active microwave studies, microwave radiometry, microwave scatterometry, side-looking radar, and synthetic aperture radar. Remote sensing of large aquatic mammals and operational ice forecasting are also discussed.

Detection of Waterborne and Airborne Formaldehyde: From Amperometric Chemosensing to a Visual Biosensor Based on Alcohol Oxidase

Directory of Open Access Journals (Sweden)

Sasi Sigawi

2014-02-01

Full Text Available A laboratory prototype of a microcomputer-based analyzer was developed for quantitative determination of formaldehyde in liquid samples, based on catalytic chemosensing elements. It was shown that selectivity for the target analyte could be increased by modulating the working electrode potential. Analytical parameters of three variants of the amperometric analyzer that differed in the chemical structure/configuration of the working electrode were studied. The constructed analyzer was tested on wastewater solutions that contained formaldehyde. A simple low-cost biosensor was developed for semi-quantitative detection of airborne formaldehyde in concentrations exceeding the threshold level. This biosensor is based on a change in the color of a solution that contains a mixture of alcohol oxidase from the yeast Hansenula polymorpha, horseradish peroxidase and a chromogen, following exposure to airborne formaldehyde. The solution is enclosed within a membrane device, which is permeable to formaldehyde vapors. The most efficient and sensitive biosensor for detecting formaldehyde was the one that contained alcohol oxidase with an activity of 1.2 U·mL−1. The biosensor requires no special instrumentation and enables rapid visual detection of airborne formaldehyde at concentrations, which are hazardous to human health.

Multiphase Reactive Transport and Platelet Ice Accretion in the Sea Ice of McMurdo Sound, Antarctica

Science.gov (United States)

Buffo, J. J.; Schmidt, B. E.; Huber, C.

2018-01-01

Sea ice seasonally to interannually forms a thermal, chemical, and physical boundary between the atmosphere and hydrosphere over tens of millions of square kilometers of ocean. Its presence affects both local and global climate and ocean dynamics, ice shelf processes, and biological communities. Accurate incorporation of sea ice growth and decay, and its associated thermal and physiochemical processes, is underrepresented in large-scale models due to the complex physics that dictate oceanic ice formation and evolution. Two phenomena complicate sea ice simulation, particularly in the Antarctic: the multiphase physics of reactive transport brought about by the inhomogeneous solidification of seawater, and the buoyancy driven accretion of platelet ice formed by supercooled ice shelf water onto the basal surface of the overlying ice. Here a one-dimensional finite difference model capable of simulating both processes is developed and tested against ice core data. Temperature, salinity, liquid fraction, fluid velocity, total salt content, and ice structure are computed during model runs. The model results agree well with empirical observations and simulations highlight the effect platelet ice accretion has on overall ice thickness and characteristics. Results from sensitivity studies emphasize the need to further constrain sea ice microstructure and the associated physics, particularly permeability-porosity relationships, if a complete model of sea ice evolution is to be obtained. Additionally, implications for terrestrial ice shelves and icy moons in the solar system are discussed.

A one stop website for sharing sea ice, ocean and ice sheet data over the polar regions

Science.gov (United States)

Chen, Z.; Cheng, X.; Liu, J.; Hui, F.; Ding, Y.

2017-12-01

The polar regions, including the Arctic and Antarctic, are changing rapidly. Our capabilities to remotely monitor the state of the polar regions are increasing greatly. Satellite and airborne technologies have been deployed and further improvements are underway. Meanwhile, various algorithms have been developed to retrieve important parameters to maximize the effectiveness of available remote sensing data. These technologies and algorithms promise to greatly increase our understanding of variations in sea ice, ocean and ice sheet. However, so much information is scattered out there. It is challenging to find exactly what you are looking for by just searching it through the network. Therefore, we try to establish a common platform to sharing some key parameters for the polar regions. A group of scientists from Beijing Normal University and University at Albany developed a website as a "one-stop shop" for the current state of the polar regions. The website provides real-time (or near real-time) key parameters derived from a variety of operational satellites in an understandable, accessible and credible way. Three types of parameter, which are sea ice, ocean and ice sheet respectively, are shown and available to be downloaded in the website. Several individual parameters are contained in a specific type of parameter. The parameters of sea ice include sea ice concentration, sea ice thickness, melt pond, sea ice leads and sea ice drift. The ocean parameters contain sea surface temperature and sea surface wind. Ice sheet balance, ice velocity and some other parameters are classified into the type of ice sheet parameter. Some parameters are well-calibrated and available to be obtained from other websites, such as sea ice concentration, sea ice thickness sea surface temperature. Since these parameters are retrieved from different sensors, such as SSMI, AMSR2 etc., data format, spatial resolution of the parameters are not unified. We collected and reprocessed these

Ice accretion modeling for wind turbine rotor blades

Energy Technology Data Exchange (ETDEWEB)

Chocron, D.; Brahimi, T.; Paraschivoiu, I.; Bombardier, J.A. [Ecole Polytechnique de Montreal (Canada)

1997-12-31

The increasing application of wind energy in northern climates implies operation of wind turbines under severe atmospheric icing conditions. Such conditions are well known in the Scandinavian countries, Canada and most of Eastern European countries. An extensive study to develop a procedure for the prediction of ice accretion on wind turbines rotor blades appears to be essential for the safe and economic operation of wind turbines in these cold regions. The objective of the present paper is to develop a computer code capable of simulating the shape and amount of ice which may accumulate on horizontal axis wind turbine blades when operating in icing conditions. The resulting code is capable to predict and simulate the formation of ice in rime and glaze conditions, calculate the flow field and particle trajectories and to perform thermodynamic analysis. It also gives the possibility of studying the effect of different parameters that influence ice formation such as temperature, liquid water content, droplet diameter and accretion time. The analysis has been conducted on different typical airfoils as well as on NASA/DOE Mod-0 wind turbine. Results showed that ice accretion on wind turbines may reduce the power output by more than 20%.

Icing conditions over Northern Eurasia in changing climate

International Nuclear Information System (INIS)

Bulygina, Olga N; Arzhanova, Natalia M; Groisman, Pavel Ya

2015-01-01

Icing conditions, particularly in combination with wind, affect greatly the operation of overhead communication and transmission lines causing serious failures, which result in tremendous economic damage. Icing formation is dangerous to agriculture, forestry, high seas fishery, for land and off coast man-made infrastructure. Quantitative icing characteristics such as weight, thickness, and duration are very important for the economy and human wellbeing when their maximum values exceed certain thresholds. Russian meteorological stations perform both visual and instrumental monitoring of icing deposits. Visual monitoring is ocular estimation of the type and intensity of icing and the date of ice appearance and disappearance. Instrumental monitoring is performed by ice accretion indicator that in addition to the type, intensity and duration of ice deposits reports also their weight and size. We used observations at 958 Russian stations for the period 1977–2013 to analyze changes in the ice formation frequency at individual meteorological stations and on the territory of quasi-homogeneous climatic regions in Russia. It was found that hoar frosts are observed in most parts of Russia, but icing only occurs in European Russia and the Far East. On the Arctic coast of Russia, this phenomenon can even be observed in summer months. Statistically significant decreasing trends in occurrence of icing and hoar frost events are found over most of Russia. An increasing trend in icing weights (IWs) was found in the Atlantic Arctic region in autumn. Statistically significant large negative trends in IWs were found in the Pacific Arctic in winter and spring. (letter)

State of Arctic Sea Ice North of Svalbard during N-ICE2015

Science.gov (United States)

Rösel, Anja; King, Jennifer; Gerland, Sebastian

2016-04-01

The N-ICE2015 cruise, led by the Norwegian Polar Institute, was a drift experiment with the research vessel R/V Lance from January to June 2015, where the ship started the drift North of Svalbard at 83°14.45' N, 21°31.41' E. The drift was repeated as soon as the vessel drifted free. Altogether, 4 ice stations where installed and the complex ocean-sea ice-atmosphere system was studied with an interdisciplinary Approach. During the N-ICE2015 cruise, extensive ice thickness and snow depth measurements were performed during both, winter and summer conditions. Total ice and snow thickness was measured with ground-based and airborne electromagnetic instruments; snow depth was measured with a GPS snow depth probe. Additionally, ice mass balance and snow buoys were deployed. Snow and ice thickness measurements were performed on repeated transects to quantify the ice growth or loss as well as the snow accumulation and melt rate. Additionally, we collected independent values on surveys to determine the general ice thickness distribution. Average snow depths of 32 cm on first year ice, and 52 cm on multi-year ice were measured in January, the mean snow depth on all ice types even increased until end of March to 49 cm. The average total ice and snow thickness in winter conditions was 1.92 m. During winter we found a small growth rate on multi-year ice of about 15 cm in 2 months, due to above-average snow depths and some extraordinary storm events that came along with mild temperatures. In contrast thereto, we also were able to study new ice formation and thin ice on newly formed leads. In summer conditions an enormous melt rate, mainly driven by a warm Atlantic water inflow in the marginal ice zone, was observed during two ice stations with melt rates of up to 20 cm per 24 hours. To reinforce the local measurements around the ship and to confirm their significance on a larger scale, we compare them to airborne thickness measurements and classified SAR-satellite scenes. The

Destruction of C2H4O2 isomers in ice-phase by X-rays: Implication on the abundance of acetic acid and methyl formate in the interstellar medium

Science.gov (United States)

Rachid, Marina G.; Faquine, Karla; Pilling, S.

2017-12-01

The C2H4O2 isomers methyl formate (HCOOCH3), acetic acid (CH3COOH) and glycoaldehyde (HOCH2CHO) have been detected in molecular clouds in the interstellar medium, as well as, hot cores, hot corinos and around protostellar objects. However, their abundances are very different, being methyl formate more abundant than the other two isomers. This fact may be related to the different destruction by ionizing radiation of these molecules. The goal of this work is experimentally study the photodissociation processes of methyl formate and acetic acid ices when exposed to broadband soft X-ray from 6 up to 2000 eV. The experiments were performed coupled to the SGM beamline in the Brazilian Synchrotron Light Source (LNLS/CNPEM) at Campinas, Brazil. The simulated astrophysical ices (12 K) were monitored throughout the experiment using infrared vibrational spectroscopy (FTIR). The analysis of processed ices allowed the determination of the effective destruction cross sections of the parent molecules as well as the effective formation cross section of daughter molecular species such as CO, CO2, H2O, CH4 and H2CO (only for methyl formate) and the hydrocarbons C2H6 and C5H10 (only for acetic acid). The half-lives of molecules at ices toward young stellar objects (YSOs) and inside molecular clouds (e.g. Sgr B2 and W51) due to the presence of incoming soft X-rays were estimated. We determined the effective formation rate and the branching ratios for assigned daughter species after the establishment of a chemical equilibrium. The main product from photodissociation of both methyl formate and acetic acid is CO, that can be formed by recombination of ions, formed during the photodissociation, in the ice surface. The relative abundance between methyl formate and acetic acid (NCH3COOH/NHCOOCH3) in different astronomical scenarios and their column density evolution in the presence of X-rays were calculated. Our results suggest that such radiation field can be one of the factors that

Proceedings of the 14. workshop of the Committee on River Ice Processes and the Environment : hydraulics of ice covered rivers

International Nuclear Information System (INIS)

Morse, B.; Bergeron, N.; Gauthier, Y.

2007-01-01

Ice processes play a significant role in the hydrologic regime of Canadian rivers. The Committee on River Ice Processes and the Environment (CRIPE) identifies high-priority topics for research and development and promotes research programs at Canadian colleges and universities. This workshop reviewed the hydraulic aspects of river ice phenomena in an effort to clarify the effects of ice cover on river flow characteristics. Other issues of concern were also discussed, notably ice formation, ice jams, winter operation of hydroelectric power plants, environmental aspects of river ice, and climate change. The workshop featured 12 poster sessions and 40 presentations, of which 5 have been catalogued separately for inclusion in this database. refs., tabs., figs

Study of Necrosis in the Liver of Formaldehyde and Benzo(αPyrene Exposured-Mice

Directory of Open Access Journals (Sweden)

Ahmad Soni

2013-04-01

Full Text Available Formaldehyde and benzo(αpyrene are compounds that harmful for health. Misapplication of this compound has an impact in the form of organ damage in the body. This study aims to determine the impact of the treatment of the combined exposure of formaldehyde and benzo(αpyrene to cell necrosis in the liver of mice (Mus musculus. Treatment of formaldehyde dose of 25 mg/kg BW to mice was given orally every day for 60 days. Treatment of benzo(αpyrene via intraperitoneal injection at a dose of 250 mg/kg BW were given after 30 days of incubation with four times injection with one day interval. Liver organ histological preparations were made through the HE staining. Observations were made by using a microscope for liver organ preparations. The data obtained that is the percentage of cells necrosis and necrotic foci. This research used Completely Randomized Design (CRD with 95% confidence interval. Liver organ preparations observations indicate that the percentage of necrosis in the untreated control, benzo(αpyrene 250 mg/kg BW, formaldehyde 25 mg/kg BW, combination of formaldehyde 25 mg/kg BW with BaP in a row that is equal to 14.43% ± 0.91; 26.05% ± 3.75; 49.38% ± 2.66; 51.86 ± 1.73. The mean of necrotic foci in liver organ formed in the untreatment control, benzo(αpyrene 250 mg/kg BW, Formaldehyde 25 mg/kg BW, and the combination of formaldehyde 25 mg/kg BW with BaP in a row, equal to 1.3 ± 0,07; 1.63 ± 0.61; 2 ± 0.51, and 3.4 ± 0.76. This suggests that the combined treatment had the highest level of toxicity compared with other treatments.

Identification of Dust and Ice Cloud Formation from A-Train Datasets

Science.gov (United States)

Russell, D. S.; Liou, K. N.

2014-12-01

Dust aerosols are effective ice nuclei for clouds and instances of nucleation have been well studied in laboratory experiments. We used CALIOP/CALIPSO, MODIS/Aqua, and CloudSat on the A-Train to find collocated instances of clouds characterized as water by MODIS, but contain ice water as indicated by CloudSat. The vertical profiles of CALIPSO detect the presence of dust and polluted dust near clouds. This study concentrates on high dust aerosol areas including the regions surrounding the Sahara Desert as well as South Asia including the Tibetan Plateau. These cases display the effects of dust acting as ice nuclei in the time frame between MODIS overpass and CloudSat overpass (~45 seconds). Utilizing available datasets, we then carried out radiative transfer calculations to understand spectral radiative forcing differences between water and ice clouds, particularly over snow surfaces at the Tibetan Plateau.

The Secret of the Svalbard Sea Ice Barrier

Science.gov (United States)

Nghiem, Son V.; Van Woert, Michael L.; Neumann, Gregory

2004-01-01

An elongated sea ice feature called the Svalbard sea ice barrier rapidly formed over an area in the Barents Sea to the east of Svalbard posing navigation hazards. The secret of its formation lies in the bottom bathymetry that governs the distribution of cold Arctic waters masses, which impacts sea ice growth on the water surface.

Biodegradation of formaldehyde from contaminated air using a laboratory scale static-bed bioreactor

Directory of Open Access Journals (Sweden)

Yaghoub Hajizadeh

2014-01-01

Full Text Available Aims: The objective of the present study was to evaluate the performance of an aerobic fixed-bed bioreactor (FBR enriched with microorganisms of sewage sludge in biodegradation of formaldehyde in air stream with various retention times and airflow rates in laboratory scale. Materials and Methods: An aerobic biofilter 60 cm in height and 14 cm internal diameter made of steel was constructed and packed with a mixture of pumice and compost as a medium and utilized in this study. The microorganism′s growth, which is derived from the sludge of a municipal wastewater treatment plant, was initiated by adding nutrient. During the first few days of run, the airflow containing different concentrations of formaldehyde (from 24 ± 3 to 224 ± 5 mg/m 3 was introduced to the reactor to ensure biological adaptation. Sampling was performed through a series of two impingers containing adsorbent, and analyzed by chromotropic acid assay using DR-5000. Results: The maximum removal and elimination capacity of formaldehyde was yielded at 0.48 ± 0.06 g/m 3 /h inlet loading rate and 180 s of empty bed retention time (EBRT. These values for stabilized days were almost 88% and 0.42 g/m 3 /h, respectively. Conclusion: The results showed that by increasing the inlet concentration of formaldehyde and reducing the EBRT, the formaldehyde removal capacity of the system decreases. Aerobic bioreactor with appropriate bed volume and compatible with inlet pollutant mass flow rate in optimum retention time will admissibly degrade and reduce the formaldehyde concentration from contaminated gas phase, such as gases produced in municipal wastewater treatment facilities.

Cystathionine metabolic enzymes play a role in the inflammation resolution of human keratinocytes in response to sub-cytotoxic formaldehyde exposure

Energy Technology Data Exchange (ETDEWEB)

Lee, Eunyoung [College of Pharmacy, Seoul National University, Seoul 08826 (Korea, Republic of); Natural Products Research Institute, Seoul National University, Seoul 08826 (Korea, Republic of); Kim, Hyoung-June [Basic Research and Innovation Division, AmorePacific Corporation R& D Center, Yongin, Gyeounggi-do 17074 (Korea, Republic of); Lee, Moonyoung [College of Pharmacy, Seoul National University, Seoul 08826 (Korea, Republic of); Jin, Sun Hee; Hong, Soo Hyun; Ahn, Seyeon; Kim, Sae On [College of Pharmacy, Seoul National University, Seoul 08826 (Korea, Republic of); Natural Products Research Institute, Seoul National University, Seoul 08826 (Korea, Republic of); Shin, Dong Wook [Basic Research and Innovation Division, AmorePacific Corporation R& D Center, Yongin, Gyeounggi-do 17074 (Korea, Republic of); Lee, Seung-Taek [Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 03722 (Korea, Republic of); Noh, Minsoo, E-mail: minsoonoh@snu.ac.kr [College of Pharmacy, Seoul National University, Seoul 08826 (Korea, Republic of); Natural Products Research Institute, Seoul National University, Seoul 08826 (Korea, Republic of)

2016-11-01

Low-level formaldehyde exposure is inevitable in industrialized countries. Although daily-life formaldehyde exposure level is practically impossible to induce cell death, most of mechanistic studies related to formaldehyde toxicity have been performed in cytotoxic concentrations enough to trigger cell death mechanism. Currently, toxicological mechanisms underlying the sub-cytotoxic exposure to formaldehyde are not clearly elucidated in skin cells. In this study, the genome-scale transcriptional analysis in normal human keratinocytes (NHKs) was performed to investigate cutaneous biological pathways associated with daily life formaldehyde exposure. We selected the 175 upregulated differentially expressed genes (DEGs) and 116 downregulated DEGs in NHKs treated with 200 μM formaldehyde. In the Gene Ontology (GO) enrichment analysis of the 175 upregulated DEGs, the endoplasmic reticulum (ER) unfolded protein response (UPR) was identified as the most significant GO biological process in the formaldeyde-treated NHKs. Interestingly, the sub-cytotoxic formaldehyde affected NHKs to upregulate two enzymes important in the cellular transsulfuration pathway, cystathionine γ-lyase (CTH) and cystathionine-β-synthase (CBS). In the temporal expression analysis, the upregulation of the pro-inflammatory DEGs such as MMP1 and PTGS2 was detected earlier than that of CTH, CBS and other ER UPR genes. The metabolites of CTH and CBS, L-cystathionine and L-cysteine, attenuated the formaldehyde-induced upregulation of pro-inflammatory DEGs, MMP1, PTGS2, and CXCL8, suggesting that CTH and CBS play a role in the negative feedback regulation of formaldehyde-induced pro-inflammatory responses in NHKs. In this regard, the sub-cytotoxic formaldehyde-induced CBS and CTH may regulate inflammation fate decision to resolution by suppressing the early pro-inflammatory response. - Highlights: • Sub-cytotoxic formaldehyde upregulates ER UPR-associated genes in NHKs. • Formaldehyde-induced ER UPR

Formaldehyde, methanol and hydrocarbon emissions from methanol-fueled cars

International Nuclear Information System (INIS)

Williams, R.L.; Lipari, F.; Potter, R.A.

1990-01-01

Exhaust and evaporative emissions tests were conducted on several methanol- and gasoline-fueled vehicles. Separate samples for chromatographic analysis of formaldehyde, methanol, and individual hydrocarbons were collected in each of the three phases of the driving cycle and in each of the two portions of the evaporative emissions test. One vehicle, equipped with an experimental variable-fuel engine, was tested using methanol/gasoline fuel mixtures of 100, 85, 50, 15, and 0 percent methanol. Combustion-generated hydrocarbons were lowest using methanol fuel, and increased several-fold as the gasoline fraction was increased. Gasoline components in the exhaust increased from zero as the gasoline fraction of the fuel was increased. On the other hand, formaldehyde emissions were several times higher using methanol fuel than they were using gasoline. A dedicated methanol car and the variable-fuel car gave similar emissions patterns when they both were tested using methanol fuel. The organic-carbon composition of the exhaust was 85-90 percent methanol, 5-7 percent formaldehyde, and 3-9 percent hydrocarbons. Several cars that were tested using gasoline emitted similar distributions of hydrocarbons, even through the vehicles represented a broad range of current and developmental engine families and emissions control systems

Mapping Ross Ice Shelf with ROSETTA-Ice airborne laser altimetry

Science.gov (United States)

Becker, M. K.; Fricker, H. A.; Padman, L.; Bell, R. E.; Siegfried, M. R.; Dieck, C. C. M.

2017-12-01

The Ross Ocean and ice Shelf Environment and Tectonic setting Through Aerogeophysical surveys and modeling (ROSETTA-Ice) project combines airborne glaciological, geological, and oceanographic observations to enhance our understanding of the history and dynamics of the large ( 500,000 square km) Ross Ice Shelf (RIS). Here, we focus on the Light Detection And Ranging (LiDAR) data collected in 2015 and 2016. This data set represents a significant advance in resolution: Whereas the last attempt to systematically map RIS (the surface-based RIGGS program in the 1970s) was at 55 km grid spacing, the ROSETTA-Ice grid has 10-20 km line spacing and much higher along-track resolution. We discuss two different strategies for processing the raw LiDAR data: one that requires proprietary software (Riegl's RiPROCESS package), and one that employs open-source programs and libraries. With the processed elevation data, we are able to resolve fine-scale ice-shelf features such as the "rampart-moat" ice-front morphology, which has previously been observed on and modeled for icebergs. This feature is also visible in the ROSETTA-Ice shallow-ice radar data; comparing the laser data with radargrams provides insight into the processes leading to their formation. Near-surface firn state and total firn air content can also be investigated through combined analysis of laser altimetry and radar data. By performing similar analyses with data from the radar altimeter aboard CryoSat-2, we demonstrate the utility of the ROSETTA-Ice LiDAR data set in satellite validation efforts. The incorporation of the LiDAR data from the third and final field season (December 2017) will allow us to construct a DEM and an ice thickness map of RIS for the austral summers of 2015-2017. These products will be used to validate and extend observations of height changes from satellite radar and laser altimetry, as well as to update regional models of ocean circulation and ice dynamics.

Organic Chemistry in Interstellar Ices: Connection to the Comet Halley Results

Science.gov (United States)

Schutte, W. A.; Agarwal, V. K.; deGroot, M. S.; Greenberg, J. M.; McCain, P.; Ferris, J. P.; Briggs, R.

1997-01-01

Mass spectroscopic measurements on the gas and dust in the coma of Comet Halley revealed the presence of considerable amounts of organic species. Greenberg (1973) proposed that prior to the formation of the comet UV processing of the ice mantles on grains in dense clouds could lead to the formation of complex organic molecules. Theoretical predictions of the internal UV field in dense clouds as well as the discovery in interstellar ices of species like OCS and OCN- which have been formed in simulation experiments by photoprocessing of interstellar ice analogues point to the importance of such processing. We undertook a laboratory simulation study of the formation of organic molecules in interstellar ices and their possible relevance to the Comet Halley results.

40 CFR 721.3800 - Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene...

Science.gov (United States)

2010-07-01

... polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. 721.3800 Section 721.3800... Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. (a... generically as formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene...

Bio-inspired design of ice-retardant devices based on benthic marine invertebrates: the effect of surface texture

Directory of Open Access Journals (Sweden)

Homayun Mehrabani

2014-09-01

Full Text Available Growth of ice on surfaces poses a challenge for both organisms and for devices that come into contact with liquids below the freezing point. Resistance of some organisms to ice formation and growth, either in subtidal environments (e.g., Antarctic anchor ice, or in environments with moisture and cold air (e.g., plants, intertidal begs examination of how this is accomplished. Several factors may be important in promoting or mitigating ice formation. As a start, here we examine the effect of surface texture alone. We tested four candidate surfaces, inspired by hard-shelled marine invertebrates and constructed using a three-dimensional printing process. We examined sub-polar marine organisms to develop sample textures and screened them for ice formation and accretion in submerged conditions using previous methods for comparison to data for Antarctic organisms. The sub-polar organisms tested were all found to form ice readily. We also screened artificial 3-D printed samples using the same previous methods, and developed a new test to examine ice formation from surface droplets as might be encountered in environments with moist, cold air. Despite limitations inherent to our techniques, it appears surface texture plays only a small role in delaying the onset of ice formation: a stripe feature (corresponding to patterning found on valves of blue mussels, Mytilus edulis, or on the spines of the Antarctic sea urchin Sterechinus neumayeri slowed ice formation an average of 25% compared to a grid feature (corresponding to patterning found on sub-polar butterclams, Saxidomas nuttalli. The geometric dimensions of the features have only a small (∼6% effect on ice formation. Surface texture affects ice formation, but does not explain by itself the large variation in ice formation and species-specific ice resistance observed in other work. This suggests future examination of other factors, such as material elastic properties and surface coatings, and their

Variability and Trends in Sea Ice Extent and Ice Production in the Ross Sea

Science.gov (United States)

Comiso, Josefino; Kwok, Ronald; Martin, Seelye; Gordon, Arnold L.

2011-01-01

Salt release during sea ice formation in the Ross Sea coastal regions is regarded as a primary forcing for the regional generation of Antarctic Bottom Water. Passive microwave data from November 1978 through 2008 are used to examine the detailed seasonal and interannual characteristics of the sea ice cover of the Ross Sea and the adjacent Bellingshausen and Amundsen seas. For this period the sea ice extent in the Ross Sea shows the greatest increase of all the Antarctic seas. Variability in the ice cover in these regions is linked to changes in the Southern Annular Mode and secondarily to the Antarctic Circumpolar Wave. Over the Ross Sea shelf, analysis of sea ice drift data from 1992 to 2008 yields a positive rate of increase in the net ice export of about 30,000 sq km/yr. For a characteristic ice thickness of 0.6 m, this yields a volume transport of about 20 cu km/yr, which is almost identical, within error bars, to our estimate of the trend in ice production. The increase in brine rejection in the Ross Shelf Polynya associated with the estimated increase with the ice production, however, is not consistent with the reported Ross Sea salinity decrease. The locally generated sea ice enhancement of Ross Sea salinity may be offset by an increase of relatively low salinity of the water advected into the region from the Amundsen Sea, a consequence of increased precipitation and regional glacial ice melt.

Optimization of Formaldehyde Cross-Linking for Protein Interaction Analysis of Non-Tagged Integrin β1

Directory of Open Access Journals (Sweden)

Cordula Klockenbusch

2010-01-01

Full Text Available Formaldehyde cross-linking of protein complexes combined with immunoprecipitation and mass spectrometry analysis is a promising technique for analysing protein-protein interactions, including those of transient nature. Here we used integrin β1 as a model to describe the application of formaldehyde cross-linking in detail, particularly focusing on the optimal parameters for cross-linking, the detection of formaldehyde cross-linked complexes, the utility of antibodies, and the identification of binding partners. Integrin β1 was found in a high molecular weight complex after formaldehyde cross-linking. Eight different anti-integrin β1 antibodies were used for pull-down experiments and no loss in precipitation efficiency after cross-linking was observed. However, two of the antibodies could not precipitate the complex, probably due to hidden epitopes. Formaldehyde cross-linked complexes, precipitated from Jurkat cells or human platelets and analyzed by mass spectrometry, were found to be composed of integrin β1, α4 and α6 or β1, α6, α2, and α5, respectively.

Optimization of Formaldehyde Cross-Linking for Protein Interaction Analysis of Non-Tagged Integrin β1

Science.gov (United States)

Klockenbusch, Cordula; Kast, Juergen

2010-01-01

Formaldehyde cross-linking of protein complexes combined with immunoprecipitation and mass spectrometry analysis is a promising technique for analysing protein-protein interactions, including those of transient nature. Here we used integrin β1 as a model to describe the application of formaldehyde cross-linking in detail, particularly focusing on the optimal parameters for cross-linking, the detection of formaldehyde cross-linked complexes, the utility of antibodies, and the identification of binding partners. Integrin β1 was found in a high molecular weight complex after formaldehyde cross-linking. Eight different anti-integrin β1 antibodies were used for pull-down experiments and no loss in precipitation efficiency after cross-linking was observed. However, two of the antibodies could not precipitate the complex, probably due to hidden epitopes. Formaldehyde cross-linked complexes, precipitated from Jurkat cells or human platelets and analyzed by mass spectrometry, were found to be composed of integrin β1, α4 and α6 or β1, α6, α2, and α5, respectively. PMID:20634879

A sea ice model for the marginal ice zone with an application to the Greenland Sea

DEFF Research Database (Denmark)

Pedersen, Leif Toudal; Coon, Max D.

2004-01-01

A model is presented that describes the formation, transport, and desalinization of frazil and pancake ice as it is formed in marginal seas. This model uses as input the total ice concentration evaluated from Special Sensor Microwave Imager and wind speed and direction. The model calculates...... the areal concentration, thickness, volume concentration, and salinity of frazil ice as well as the areal concentration, thickness, and salinity of pancakes. A simple parameterization for the Odden region of the Greenland Sea is presented. The model is run for the winter of 1996-1997. There are direct...... observations of the thickness and salinity of pancakes and the volume concentration of frazil ice to compare with the model. The model results compare very well with the measured data. This new ice model can be tuned to work in marginal seas elsewhere to calculate ice thickness, motion, and brine rejection...

Classification of new-ice in the Greenland Sea using Satellite SSM/I radiometer and SeaWinds scatterometer data and comparison with ice model

DEFF Research Database (Denmark)

Tonboe, Rasmus; Pedersen, Leif Toudal

2005-01-01

In the ice covered waters of the Greenland Sea the polarisation ratio of QuikSCAT SeaWinds Ku-band (13.4 GHz) scatterometer measurements and the polarisation ratio of DMSP-SSM/I 19 GHz radiometer measurements are used in combination to classify new-ice and mature ice. In particular, the formation...... to the physical transition of the ice cover from pancake ice to a consolidated young-ice sheet. The classification of each pixel into ice or water is done using two scatterometer parameters, namely the polarisation ratio and the daily standard deviation of the backscatter. (C) 2005 Elsevier Inc. All rights...

Formation of Glycerol through Hydrogenation of CO Ice under Prestellar Core Conditions

Science.gov (United States)

Fedoseev, G.; Chuang, K.-J.; Ioppolo, S.; Qasim, D.; van Dishoeck, E. F.; Linnartz, H.

2017-06-01

Observational studies reveal that complex organic molecules (COMs) can be found in various objects associated with different star formation stages. The identification of COMs in prestellar cores, I.e., cold environments in which thermally induced chemistry can be excluded and radiolysis is limited by cosmic rays and cosmic-ray-induced UV photons, is particularly important as this stage sets up the initial chemical composition from which ultimately stars and planets evolve. Recent laboratory results demonstrate that molecules as complex as glycolaldehyde and ethylene glycol are efficiently formed on icy dust grains via nonenergetic atom addition reactions between accreting H atoms and CO molecules, a process that dominates surface chemistry during the “CO freeze-out stage” in dense cores. In the present study we demonstrate that a similar mechanism results in the formation of the biologically relevant molecule glycerol—HOCH2CH(OH)CH2OH—a three-carbon-bearing sugar alcohol necessary for the formation of membranes of modern living cells and organelles. Our experimental results are fully consistent with a suggested reaction scheme in which glycerol is formed along a chain of radical-radical and radical-molecule interactions between various reactive intermediates produced upon hydrogenation of CO ice or its hydrogenation products. The tentative identification of the chemically related simple sugar glyceraldehyde—HOCH2CH(OH)CHO—is discussed as well. These new laboratory findings indicate that the proposed reaction mechanism holds much potential to form even more complex sugar alcohols and simple sugars.

Multicenter Patch Testing With a Resol Resin Based on Phenol and Formaldehyde Within the International Contact Dermatitis Research Group

DEFF Research Database (Denmark)

Isaksson, M.; Ale, I.; Andersen, Klaus Ejner

2015-01-01

Background Contact allergy to phenol-formaldehyde resins (PFRs) based on phenol and formaldehyde is not detected by a p-tertiary-butylphenol-formaldehyde resin included in most baseline patch test series. Objective The aims of this study were to investigate the contact allergy rate to PFR-2.......2%) reacted to PFR-2. Of those 28 individuals, one had a positive reaction to formaldehyde and 2 to p-tertiary-butylphenol-formaldehyde resin. Simultaneous allergic reactions were noted to colophonium in 3, to Myroxylon pereirae in 5, and to fragrance mix I in 8. Conclusions The contact allergy frequency...

Optical chemical sensors for atmospheric pollutants based on nano porous materials: application to the formaldehyde and the other carbonyl compounds

International Nuclear Information System (INIS)

Paolacci, H.

2006-12-01

Formaldehyde, a well-identified indoor pollutant, was recently classified as carcinogenic. New regulations for the air quality are expected and therefore there is a need for low-cost sensors, sensitive and selective with a fast response time for the detection of formaldehyde at ppb level. In the present work, we had developed a chemical sensor based on nano-porous matrices doped with Fluoral-P and optical methods of detection. The nano-porous matrices, elaborated via the Sol-Gel process, display nano-pores whose cavity is tailored for the trapping of the targeted pollutant. They provide a first selectivity with the discrimination of the pollutants by their size. A second selectivity is obtained with a molecular probe, Fluoral-P, which reacts specifically with formaldehyde leading to the 3,5- di-acetyl-1,4-dihydro-lutidine (DDL). The kinetics of formation of DDL was studied as function of many parameters such as the concentration of Fluoral-P in the matrix, the pollutant content in gas mixture, the flow rate, the relative humidity of the gas mixtures and interference with other carbonylated compounds. The present chemical sensor can detect, via absorbance measurements, 2 ppb of formaldehyde within 30 min over a O to 60% relative humidity range. Moreover, to detect the total carbonylated compounds, we also explored the potentiality of a chemical sensor using, as a probe molecule, the 2'4-dinitro-phenyl-hydrazine which forms with these compounds the corresponding hydrazones derivatives. A patent was deposited for these two sensors. We have also developed a semi-miniaturized prototype for demonstration, using a flow cell, a miniaturized spectrophotometer, a light source and a lap-top. (author)

International Workshop on Comparing Ice Nucleation Measuring Systems 2014

Energy Technology Data Exchange (ETDEWEB)

Cziczo, Daniel [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

2016-04-30

The relationship of ambient aerosol particles to the formation of ice-containing clouds is one of the largest uncertainties in understanding the Earth’s climate. The uncertainty is due to several poorly understood processes and measurements including, but not limited to: (1) the microphysics of how particles nucleate ice, (2) the number of ice forming particles as a function of atmospheric properties such as temperature and relative humidity, (3) the atmospheric distribution of ice forming particles and (4) the role of anthropogenic activities in producing or changing the behavior of ice forming particles. The ways in which ice forming particles can impact climate is also multi-faceted. More ice forming particles can lead to clouds with more ice crystals and different optical properties than clouds with less ice forming particles. More effective ice forming particles can lead to ice at higher temperature and/or lower saturation, resulting in clouds at lower altitude or latitude which also changes the Earth’s radiative balance. Ice nucleation also initiates most of the Earth’s precipitation, even in the mid- and low-latitudes, since cloud-top temperatures are often below freezing. The limited measurements and lack of understanding directly translates to restrictions in our ability to model atmospheric ice formation and project changes into the future. The importance of ice nucleation research is further exemplified by Figure 1 which shows the publications per decade and citations per year on the topic of ice nucleation [DeMott et al., 2011]. After a lull at the end of the last century, there has been a dramatic increase in both publications and citations related to ice nucleation; this directly corresponds to the importance of ice nucleation on the Earth’s climate and the uncertainty in this area noted by the Solomon [2007].

Frazil-ice growth rate and dynamics in mixed layers and sub-ice-shelf plumes

Science.gov (United States)

Rees Jones, David W.; Wells, Andrew J.

2018-01-01

The growth of frazil or granular ice is an important mode of ice formation in the cryosphere. Recent advances have improved our understanding of the microphysical processes that control the rate of ice-crystal growth when water is cooled beneath its freezing temperature. These advances suggest that crystals grow much faster than previously thought. In this paper, we consider models of a population of ice crystals with different sizes to provide insight into the treatment of frazil ice in large-scale models. We consider the role of crystal growth alongside the other physical processes that determine the dynamics of frazil ice. We apply our model to a simple mixed layer (such as at the surface of the ocean) and to a buoyant plume under a floating ice shelf. We provide numerical calculations and scaling arguments to predict the occurrence of frazil-ice explosions, which we show are controlled by crystal growth, nucleation, and gravitational removal. Faster crystal growth, higher secondary nucleation, and slower gravitational removal make frazil-ice explosions more likely. We identify steady-state crystal size distributions, which are largely insensitive to crystal growth rate but are affected by the relative importance of secondary nucleation to gravitational removal. Finally, we show that the fate of plumes underneath ice shelves is dramatically affected by frazil-ice dynamics. Differences in the parameterization of crystal growth and nucleation give rise to radically different predictions of basal accretion and plume dynamics, and can even impact whether a plume reaches the end of the ice shelf or intrudes at depth.

Airborne In-Situ Measurements of Formaldehyde Over California: First Results from the Compact Formaldehyde Fluorescence Experiment (COFFEE) Instrument

Science.gov (United States)

Marrero, Josette Elizabeth; Saint Clair, Jason; Yates, Emma L.; Gore, Warren; Swanson, Andrew K.; Iraci, Laura T.; Hanisco, Thomas F.

2016-01-01

Formaldehyde (HCHO) is one of the most abundant oxygenated volatile organic compounds (VOCs) in the atmosphere, playing a role multiple atmospheric processes. Measurements of HCHO can be used to help quantify convective transport, the abundance of VOCs, and ozone production in urban environments. The Compact Formaldehyde FluorescencE Experiment (COFFEE) instrument uses Non-Resonant Laser Induced Fluorescence (NR-LIF) to detect trace concentrations of HCHO as part of the Alpha Jet Atmospheric eXperiment (AJAX) payload. Developed at NASA GSFC, COFFEE is a small, low maintenance instrument with a sensitivity of 100 pptv and a quick response time (1 sec). The COFFEE instrument has been customized to fit in an external wing pod on the Alpha Jet aircraft based at NASA ARC. The instrument can operate over a broad range of altitudes, from boundary layer to lower stratosphere, making it well suited for the Alpha Jet, which can access altitudes from the surface up to 40,000 ft. Results of the first COFFEE science flights preformed over the California's Central Valley will be presented. Boundary layer measurements and vertical profiles in the tropospheric column will both be included. This region is of particular interest, due to its elevated levels of HCHO, revealed in satellite images, as well as its high ozone concentrations. In addition to HCHO, the AJAX payload includes measurements of atmospheric ozone, methane, and carbon dioxide. Formaldehyde is one of the few urban pollutants that can be measured from space. Plans to compare in-situ COFFEE data with satellite-based HCHO observations such as those from OMI (Aura) and OMPS (SuomiNPP) will also be presented.

Arctic landfast sea ice

Science.gov (United States)

Konig, Christof S.

Landfast ice is sea ice which forms and remains fixed along a coast, where it is attached either to the shore, or held between shoals or grounded icebergs. Landfast ice fundamentally modifies the momentum exchange between atmosphere and ocean, as compared to pack ice. It thus affects the heat and freshwater exchange between air and ocean and impacts on the location of ocean upwelling and downwelling zones. Further, the landfast ice edge is essential for numerous Arctic mammals and Inupiat who depend on them for their subsistence. The current generation of sea ice models is not capable of reproducing certain aspects of landfast ice formation, maintenance, and disintegration even when the spatial resolution would be sufficient to resolve such features. In my work I develop a new ice model that permits the existence of landfast sea ice even in the presence of offshore winds, as is observed in mature. Based on viscous-plastic as well as elastic-viscous-plastic ice dynamics I add tensile strength to the ice rheology and re-derive the equations as well as numerical methods to solve them. Through numerical experiments on simplified domains, the effects of those changes are demonstrated. It is found that the modifications enable landfast ice modeling, as desired. The elastic-viscous-plastic rheology leads to initial velocity fluctuations within the landfast ice that weaken the ice sheet and break it up much faster than theoretically predicted. Solving the viscous-plastic rheology using an implicit numerical method avoids those waves and comes much closer to theoretical predictions. Improvements in landfast ice modeling can only verified in comparison to observed data. I have extracted landfast sea ice data of several decades from several sources to create a landfast sea ice climatology that can be used for that purpose. Statistical analysis of the data shows several factors that significantly influence landfast ice distribution: distance from the coastline, ocean depth, as

High density amorphous ice and its phase transition to ice XII

International Nuclear Information System (INIS)

Kohl, I.

2001-07-01

1998 Lobban et al. reported the neutron diffraction data of a new phase of ice, called ice XII, which formed at 260 K on compression of water within the domain of ice V at a pressure of 0.5 GPa. Surprisingly ice XII forms as an incidental product in the preparation of high-density amorphous ice (HDA) on compression of hexagonale ice (ice Ih) at 77 K up to pressures = 1.3 GPa. A decisive experimental detail is the use of an indium container: when compressing ice Ih in a pressure vessel with indium linings, then reproducibly HDA (high density amorphous ice) forms, but without indium randomly scattered relative amounts of ice XII and HDA form. Ice XII forms on compression of ice Ih at 77 K only via HDA, and not directly from ice Ih. Its formation requires a sudden pronounced apparent pressure drop of ca 0.18 GPa at pressures ca 1.1 GPa. These apparent pressure drops can be caused by buildup friction between the piston and the pressure vessel and its sudden release on further compression. I propose that shock-waves generated by apparent pressure drops cause transient local heating and that this induces nucleation and crystal growth. A specific reproducible method to prepare ice XII is heating HDA in a pressure vessel with indium linings at constant pressures (or constant volume). The ice XII (meta-)stability domain extends between ca 158 and 212 K from ca 0.7 to ca 1.5 GPa. DSC (differential scanning calorimetry) and x-ray powder diffraction revealed, that on heating at atmospheric pressure ice XII transforms directly into cubic ice (ice Ic) at 154 K (heating rate 10 K min - 1) and not into an amorphous form before transition to ice Ic. The enthalpy of the ice XII - ice Ic transition is -1.21 ± 0.07 kJ mol -1 . An estimation of the Gibbs free energy at atmospheric pressure and about 140 K results that ice XII is thermodynamically more stable than ice VI. In the heating curve of ice XII a reversible endothermic step can be found at the onset temperature (heating rate

On the Ice Nucleation Spectrum

Science.gov (United States)

Barahona, D.

2012-01-01

This work presents a novel formulation of the ice nucleation spectrum, i.e. the function relating the ice crystal concentration to cloud formation conditions and aerosol properties. The new formulation is physically-based and explicitly accounts for the dependency of the ice crystal concentration on temperature, supersaturation, cooling rate, and particle size, surface area and composition. This is achieved by introducing the concepts of ice nucleation coefficient (the number of ice germs present in a particle) and nucleation probability dispersion function (the distribution of ice nucleation coefficients within the aerosol population). The new formulation is used to generate ice nucleation parameterizations for the homogeneous freezing of cloud droplets and the heterogeneous deposition ice nucleation on dust and soot ice nuclei. For homogeneous freezing, it was found that by increasing the dispersion in the droplet volume distribution the fraction of supercooled droplets in the population increases. For heterogeneous ice nucleation the new formulation consistently describes singular and stochastic behavior within a single framework. Using a fundamentally stochastic approach, both cooling rate independence and constancy of the ice nucleation fraction over time, features typically associated with singular behavior, were reproduced. Analysis of the temporal dependency of the ice nucleation spectrum suggested that experimental methods that measure the ice nucleation fraction over few seconds would tend to underestimate the ice nuclei concentration. It is shown that inferring the aerosol heterogeneous ice nucleation properties from measurements of the onset supersaturation and temperature may carry significant error as the variability in ice nucleation properties within the aerosol population is not accounted for. This work provides a simple and rigorous ice nucleation framework where theoretical predictions, laboratory measurements and field campaign data can be

Formation of carbonyl compounds in radiolysis of ethylene glycol in methanol

International Nuclear Information System (INIS)

Bezborodova, S.G.; Vetrov, V.S.; Kalyazin, E.P.; Korolev, V.M.; Salamatov, I.I.

1977-01-01

Radiolysis of diluted solutions of ethylene glycol has been investigated. It is shown that acetaldehyde, glycol aldehyde and formaldehyde are the main products of radiolysis of methanol solutions of ethylene glycol. Acetaldehyde and glycol aldehyde yields increase in radiolysis of methanol solutions of ethylene glycol with an increase of the original concentration of ethylene glycol and a temperature rise of radiolysis. Formaldehyde yields increase with the ethylene glycol concentration but decrease with a temperature rise (the formation of formaldehyde from methanol is taken into account). A mechanism of radiation-chemical transformations of ethylene glycol in methanol is explained. It is concluded that the main directions of ethylene glycol decomposition, detected in water solutions of ethylene glycol, are also realized in methanol solutions. However, a role of different directions of decomposition depends on the medium

Gas-diffusion microextraction coupled with spectrophotometry for the determination of formaldehyde in cork agglomerates.

Science.gov (United States)

Brandão, Pedro F; Ramos, Rui M; Valente, Inês M; Almeida, Paulo J; Carro, Antonia M; Lorenzo, Rosa A; Rodrigues, José A

2017-04-01

In this work, a simple methodology was developed for the extraction and determination of free formaldehyde content in cork agglomerate samples. For the first time, gas-diffusion microextraction was used for the extraction of volatile formaldehyde directly from samples, with simultaneous derivatization with acetylacetone (Hantzsch reaction). The absorbance of the coloured solution was read in a spectrophotometer at 412 nm. Different extraction parameters were studied and optimized (extraction temperature, sample mass, volume of acceptor solution, extraction time and concentration of derivatization reagent) by means of an asymmetric screening. The developed methodology proved to be a reliable tool for the determination of formaldehyde in cork agglomerates with the following suitable method features: low LOD (0.14 mg kg -1 ) and LOQ (0.47 mg kg -1 ), r 2  = 0.9994, and intraday and interday precision of 3.5 and 4.9%, respectively. The developed methodology was applied to the determination of formaldehyde in different cork agglomerate samples, and contents between 1.9 and 9.4 mg kg -1 were found. Furthermore, formaldehyde was also determined by the standard method EN 717-3 for comparison purposes; no significant differences between the results of both methods were observed. Graphical abstract Representation of the GDME system and its main components.

Formaldehyde and TVOC emission behavior of laminate flooring by structure of laminate flooring and heating condition.

Science.gov (United States)

An, Jae-Yoon; Kim, Sumin; Kim, Hyun-Joong

2011-03-15

Formaldehyde was measured with a desiccator, a 20 L chamber and the FLEC method. The formaldehyde emission rate from laminate was the highest at 32 °C using the desiccator, which then decreased with time. The formaldehyde emission using the 20 L small chamber and FLEC showed a similar tendency. There was a strong correlation between the formaldehyde and total volatile organic compounds (TVOCs) with both types of floorings using the two different methods. The formaldehyde emission rate and TVOC results were higher when tested using the FLEC method than with the 20 L small chamber method. The emission rate was affected by the joint edge length in laminate flooring. Toluene, ethylbenzene and xylene were the main VOCs emitted from laminate flooring, and there were more unidentified VOCs emitted than identified VOCs. The samples heated with a floor heating system emitted more formaldehyde than those heated using an air circulation system due to the temperature difference between the bottom panel and flooring. The TVOC emission level of the samples was higher when an air circulation system was used than when a floor heating system was used due to the high ventilation rate. Copyright © 2010 Elsevier B.V. All rights reserved.

Ice-Cliff Failure via Retrogressive Slumping

Science.gov (United States)

Parizek, B. R.; Christianson, K.; Alley, R. B.; Voytenko, D.; Vankova, I.; Dixon, T. H.; Holland, D.

2016-12-01

The magnitude and rate of future sea-level rise from warming-induced ice-sheet shrinkage remain notably uncertain. Removal of most of an ice sheet by surface melting alone requires centuries to millennia. Oceanic warming may accelerate loss by removing buttressing ice shelves and thereby speeding flow of non-floating ice into the ocean, but, until recently, modeled timescales for major dynamic ice-sheet shrinkage were centuries or longer. Beyond certain thresholds, however, observations show that warming removes floating ice shelves, leaving grounded ice cliffs from which icebergs break off directly. Cliffs higher than some limit experience rapid structural failure. Recent parameterization of this process in a comprehensive ice-flow model produced much faster sea-level rise from future rapid warming than in previous modeling studies, through formation and retreat of tall ice cliffs. Fully physical representations of this process are not yet available, however. Here, we use modeling guided by terrestrial radar data from Helheim Glacier, Greenland to show that cliffs will fail by slumping and trigger rapid retreat at a threshold height that, in crevassed ice with surface melting, may be only slightly above the 100-m maximum observed today, but may be roughly twice that (180-275 m) in mechanically-competent ice under well-drained or low-melt conditions.

Experimental evidence for carbonate precipitation and CO 2 degassing during sea ice formation

Science.gov (United States)

Papadimitriou, S.; Kennedy, H.; Kattner, G.; Dieckmann, G. S.; Thomas, D. N.

2004-04-01

Chemical and stable carbon isotopic modifications during the freezing of artificial seawater were measured in four 4 m 3 tank incubations. Three of the four incubations were inoculated with a nonaxenic Antarctic diatom culture. The 18 days of freezing resulted in 25 to 27 cm thick ice sheets overlying the residual seawater. The ice phase was characterized by a decrease in temperature from -1.9 to -2.2°C in the under-ice seawater down to -6.7°C in the upper 4 cm of the ice sheet, with a concurrent increase in the salinity of the under-ice seawater and brine inclusions of the ice sheet as a result of physical concentration of major dissolved salts by expulsion from the solid ice matrix. Measurements of pH, total dissolved inorganic carbon (C T) and its stable isotopic composition (δ 13C T) all exhibited changes, which suggest minimal effect by biological activity during the experiment. A systematic drop in pH and salinity-normalized C T by up to 0.37 pH SWS units and 376 μmol C kg -1 respectively at the lowest temperature and highest salinity part of the ice sheet were coupled with an equally systematic 13C enrichment of the C T. Calculations based on the direct pH and C T measurements indicated a steady increase in the in situ concentration of dissolved carbon dioxide (CO 2(aq)) with time and increasing salinity within the ice sheet, partly due to changes in the dissociation constants of carbonic acid in the low temperature-high salinity range within sea ice. The combined effects of temperature and salinity on the solubility of CO 2 over the range of conditions encountered during this study was a slight net decrease in the equilibrium CO 2(aq) concentration as a result of the salting-out overriding the increase in solubility with decreasing temperature. Hence, the increase in the in situ CO 2(aq) concentration lead to saturation or supersaturation of the brine inclusions in the ice sheet with respect to atmospheric pCO 2 (≈3.5 × 10 -4 atm). When all physico

Adsorption of Pb, Cd, Zn, Cu and Hg ions on Formaldehyde and ...

African Journals Online (AJOL)

Adsorption of Pb(II), Cd(II), Zn(II), Cu(II) and Hg(II) ions on formaldehyde and Pyridine modified bean husks were determined. The adsorption capacity of formaldehyde modified bean husks (mg/g) was: Pb2+, 5.01; Cd2+, 3.63; Zn2+, 2.18; Hg2+, 1.82; Cu2+, 1.58 and that of pyridine modified bean husk was: Hg2+, 6.92; Cd2+ ...

Cohort mortality study of garment industry workers exposed to formaldehyde: update and internal comparisons.

Science.gov (United States)

Meyers, Alysha R; Pinkerton, Lynne E; Hein, Misty J

2013-09-01

To further evaluate the association between formaldehyde and leukemia, we extended follow-up through 2008 for a cohort mortality study of 11,043 US formaldehyde-exposed garment workers. We computed standardized mortality ratios and standardized rate ratios stratified by year of first exposure, exposure duration, and time since first exposure. Associations between exposure duration and rates of leukemia and myeloid leukemia were further examined using Poisson regression models. Compared to the US population, myeloid leukemia mortality was elevated but overall leukemia mortality was not. In internal analyses, overall leukemia mortality increased with increasing exposure duration and this trend was statistically significant. We continue to see limited evidence of an association between formaldehyde and leukemia. However, the extended follow-up did not strengthen previously observed associations. In addition to continued epidemiologic research, we recommend further research to evaluate the biological plausibility of a causal relation between formaldehyde and leukemia. Copyright © 2013 Wiley Periodicals, Inc.

Influence of Ice Nuclei Parameterization Schemes on the Hail Process

Directory of Open Access Journals (Sweden)

Xiaoli Liu

2018-01-01

Full Text Available Ice nuclei are very important factors as they significantly affect the development and evolvement of convective clouds such as hail clouds. In this study, numerical simulations of hail processes in the Zhejiang Province were conducted using a mesoscale numerical model (WRF v3.4. The effects of six ice nuclei parameterization schemes on the macroscopic and microscopic structures of hail clouds were compared. The effect of the ice nuclei concentration on ground hailfall is stronger than that on ground rainfall. There were significant spatiotemporal, intensity, and distribution differences in hailfall. Changes in the ice nuclei concentration caused different changes in hydrometeors and directly affected the ice crystals, and, hence, the spatiotemporal distribution of other hydrometeors and the thermodynamic structure of clouds. An increased ice nuclei concentration raises the initial concentration of ice crystals with higher mixing ratio. In the developing and early maturation stages of hail cloud, a larger number of ice crystals competed for water vapor with increasing ice nuclei concentration. This effect prevents ice crystals from maturing into snow particles and inhibits the formation and growth of hail embryos. During later maturation stages, updraft in the cloud intensified and more supercooled water was transported above the 0°C level, benefitting the production and growth of hail particles. An increased ice nuclei concentration therefore favors the formation of hail.

Kinetic boundaries and phase transformations of ice i at high pressure

Science.gov (United States)

Wang, Yu; Zhang, Huichao; Yang, Xue; Jiang, Shuqing; Goncharov, Alexander F.

2018-01-01

Raman spectroscopy in diamond anvil cells has been employed to study phase boundaries and transformation kinetics of H2O ice at high pressures up to 16 GPa and temperatures down to 15 K. Ice i formed at nearly isobaric cooling of liquid water transforms on compression to high-density amorphous (HDA) ice at 1.1-3 GPa at 15-100 K and then crystallizes in ice vii with the frozen-in disorder (ice vii') which remains stable up to 14.1 GPa at 80 K and 15.9 GPa at 100 K. Unexpectedly, on decompression of ice vii', it transforms to ice viii in its domain of metastability, and then it relaxes into low-density amorphous (LDA) ice on a subsequent pressure release and warming up. On compression of ice i at 150-170 K, ice ix is crystallized and no HDA ice is found; further compression of ice ix results in the sequential phase transitions to stable ices vi and viii. Cooling ice i to 210 K at 0.3 GPa transforms it to a stable ice ii. Our extensive investigations provide previously missing information on the phase diagram of water, especially on the kinetic paths that result in formation of phases which otherwise are not accessible; these results are keys for understanding the phase relations including the formation of metastable phases. Our observations inform on the ice modifications that can occur naturally in planetary environments and are not accessible for direct observations.

Beyond SHARP-- Primary Formaldehyde from Oil and Gas Exploration and Production in the Gulf of Mexico Region

Science.gov (United States)

Olaguer, E. P.

2010-12-01

Formaldehyde has been named by the EPA as a hazardous air pollutant that may be carcinogenic and also cause irritation to the eyes, nose, throat and lung. Moreover, it is a powerful radical and ozone precursor. The 2009 Study of Houston Atmospheric Radical Precursors (SHARP) was conceived by the Houston Advanced Research Center (HARC) on behalf of the Texas Environmental Research Consortium (TERC) to examine the relative importance of primary and secondary formaldehyde (HCHO) and nitrous acid (HONO) in ozone formation. SHARP confirmed that primary combustion sources of HCHO, such as flares end engines, may be underestimated (by an order of magnitude or more) in official emission inventories used for the purpose of air quality modeling in highly industrialized areas such as Houston. This presentation provides recently generated modeling and observational evidence that the same may be true in both rural and urban areas with oil and gas exploration and production (E&P) activities, such as the Upper Green River Basin of Wyoming and the Barnett Shale of Texas. Oil and gas E&P is increasing in the Gulf of Mexico region, particularly in the Barnett, Haynesville, Eagle Ford, Cana-Woodford, and Fayetteville shale basins. In the Barnett Shale, E&P activities are moving into urban neighborhoods, and may affect the ability to bring the Dallas-Ft. Worth region into attainment of the federal ozone standard. Data concerning formaldehyde emissions from drill rig and pipeline compressor engines, flares, and glycol or amine reboilers, should be obtained in order to more accurately model air quality in the Gulf of Mexico region.

CCQM-K90, formaldehyde in nitrogen, 2 μmol mol-1 Final report

Science.gov (United States)

Viallon, Joële; Flores, Edgar; Idrees, Faraz; Moussay, Philippe; Wielgosz, Robert Ian; Kim, D.; Kim, Y. D.; Lee, S.; Persijn, S.; Konopelko, L. A.; Kustikov, Y. A.; Malginov, A. V.; Chubchenko, I. K.; Klimov, A. Y.; Efremova, O. V.; Zhou, Z.; Possolo, A.; Shimosaka, T.; Brewer, P.; Macé, T.; Ferracci, Valerio; Brown, Richard J. C.; Aoki, Nobuyuki

2017-01-01

The CCQM-K90 comparison is designed to evaluate the level of comparability of national metrology institutes (NMI) or designated institutes (DI) measurement capabilities for formaldehyde in nitrogen at a nominal mole fraction of 2 μmol mol-1. The comparison was organised by the BIPM using a suite of gas mixtures prepared by a producer of specialty calibration gases. The BIPM assigned the formaldehyde mole fraction in the mixtures by comparison with primary mixtures generated dynamically by permeation coupled with continuous weighing in a magnetic suspension balance. The BIPM developed two dynamic sources of formaldehyde in nitrogen that provide two independent values of the formaldehyde mole fraction: the first one based on diffusion of trioxane followed by thermal conversion to formaldehyde, the second one based on permeation of formaldehyde from paraformaldehyde contained in a permeation tube. Two independent analytical methods, based on cavity ring down spectroscopy (CRDS) and Fourier transform infrared spectroscopy (FTIR) were used for the assignment procedure. Each participating institute was provided with one transfer standard and value assigned the formaldehyde mole fraction in the standard based on its own measurement capabilities. The stability of the formaldehyde mole fraction in transfer standards was deduced from repeated measurements performed at the BIPM before and after measurements performed at participating institutes. In addition, 5 control standards were kept at the BIPM for regular measurements during the course of the comparison. Temporal trends that approximately describe the linear decrease of the amount-of-substance fraction of formaldehyde in nitrogen in the transfer standards over time were estimated by two different mathematical treatments, the outcomes of which were proposed to participants. The two treatments also differed in the way measurement uncertainties arising from measurements performed at the BIPM were propagated to the

Soot Aerosol Particles as Cloud Condensation Nuclei: from Ice Nucleation Activity to Ice Crystal Morphology

Science.gov (United States)

Pirim, Claire; Ikhenazene, Raouf; Ortega, Isamel Kenneth; Carpentier, Yvain; Focsa, Cristian; Chazallon, Bertrand; Ouf, François-Xavier

2016-04-01

Emissions of solid-state particles (soot) from engine exhausts due to incomplete fuel combustion is considered to influence ice and liquid water cloud droplet activation [1]. The activity of these aerosols would originate from their ability to be important centers of ice-particle nucleation, as they would promote ice formation above water homogeneous freezing point. Soot particles are reported to be generally worse ice nuclei than mineral dust because they activate nucleation at higher ice-supersaturations for deposition nucleation and at lower temperatures for immersion freezing than ratios usually expected for homogeneous nucleation [2]. In fact, there are still numerous opened questions as to whether and how soot's physico-chemical properties (structure, morphology and chemical composition) can influence their nucleation ability. Therefore, systematic investigations of soot aerosol nucleation activity via one specific nucleation mode, here deposition nucleation, combined with thorough structural and compositional analyzes are needed in order to establish any association between the particles' activity and their physico-chemical properties. In addition, since the morphology of the ice crystals can influence their radiative properties [3], we investigated their morphology as they grow over both soot and pristine substrates at different temperatures and humidity ratios. In the present work, Combustion Aerosol STandart soot samples were produced from propane using various experimental conditions. Their nucleation activity was studied in deposition mode (from water vapor), and monitored using a temperature-controlled reactor in which the sample's relative humidity is precisely measured with a cryo-hygrometer. Formation of water/ice onto the particles is followed both optically and spectroscopically, using a microscope coupled to a Raman spectrometer. Vibrational signatures of hydroxyls (O-H) emerge when the particle becomes hydrated and are used to characterize ice

Airborne observations of changes of ice sheet and sea ice in the Arctic using CryoVEx campaign data

DEFF Research Database (Denmark)

Hvidegaard, Sine Munk; Skourup, Henriette; Forsberg, René

measurements of ice sheet changes. The majority of the campaigns have been sponsored by the European Space Agency, ESA, as part of the CryoSat Validation Experiments – CryoVEx. These have been internationally coordinated efforts to collect coincident space‐borne, airborne, and in‐situ data for pre‐ and post...... cap (Svalbard), the EGIG line crossing the Greenland Ice Sheet, as well as the sea ice north of Alert and sea ice around Svalbard in the Fram Strait. Selected tracks were planned to match CryoSat‐2 passes and a few of them were flown in formation flight with the Alfred Wegener Institute (AWI) Polar‐5...

Organic compounds and suspended matter in the marine ice of the Eastern Antarctic

International Nuclear Information System (INIS)

Nemirovskaya, I.A.; Novigatsky, A.N.

2005-01-01

Data on the composition of organic compounds in Antarctic sea ice are virtually non-existent, as most works concentrate on the structure, physical composition and biological properties of the ice. Data is needed for the study of the global carbon cycle and the estimation of background values and anthropogenic compounds. Specific features of the hydrometeorological regime near Antarctica affect the structure of the ice cover and its properties. The transportation of large volumes of snow to the ocean results in the formation of a snow sludge layer which gradually accumulates on the sea surface and freezes into young slush ice. The irregular distribution of snow at the ice surface and seawater infiltration results in the formation of ice with a specific crystalline structure and physiochemical properties. This paper discussed the dissolved and suspended lipids and hydrocarbons, as well as suspended matter (SM) concentrations in snow, sea ice and sub-ice water in coastal zones of the East Antarctic. The data was obtained during the Russian Antarctic Expedition in 2003. Variations in the concentration and distribution of the various substances suggest that they are related to ice forming conditions and to the processes that occur when ice forms, as well as in the interaction of the substances with ice, snow and sub-ice water. The SM and organic compounds are accumulated in layers characterized by intense autochthonous processes. It was noted that the zones stay biogeochemically active even under low temperature conditions. The highest concentrations of organic compounds, along with the biggest variations in their proportions have been discovered in the areas surrounded by penguin colonies near Buromsky Island and Haswell Island's Lake. The presence of significant quantities of PAHs in both pack and seasonal ice of high latitudes indicates that their formation is relatively rapid even at low temperatures. Many biochemical processes are intense under the influence of ice

40 CFR 721.10189 - Fatty acids, tall-oil, reaction products with (butoxymethyl) oxirane formaldehyde-phenol polymer...

Science.gov (United States)

2010-07-01

... products with (butoxymethyl) oxirane formaldehyde-phenol polymer glycidyl ether, morpholinepropanamine...-phenol polymer glycidyl ether, morpholinepropanamine, propylene glycol diamine and aliphatic polyamine, N... products with (butoxymethyl) oxirane formaldehyde-phenol polymer glycidyl ether, morpholinepropanamine...

Formation of Glycerol through Hydrogenation of CO Ice under Prestellar Core Conditions

Energy Technology Data Exchange (ETDEWEB)

Fedoseev, G.; Chuang, K.-J.; Qasim, D.; Linnartz, H. [Sackler Laboratory for Astrophysics, Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden (Netherlands); Ioppolo, S. [School of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Dishoeck, E. F. van, E-mail: gfedo@oact.inaf.it [Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden (Netherlands)

2017-06-10

Observational studies reveal that complex organic molecules (COMs) can be found in various objects associated with different star formation stages. The identification of COMs in prestellar cores, i.e., cold environments in which thermally induced chemistry can be excluded and radiolysis is limited by cosmic rays and cosmic-ray-induced UV photons, is particularly important as this stage sets up the initial chemical composition from which ultimately stars and planets evolve. Recent laboratory results demonstrate that molecules as complex as glycolaldehyde and ethylene glycol are efficiently formed on icy dust grains via nonenergetic atom addition reactions between accreting H atoms and CO molecules, a process that dominates surface chemistry during the “CO freeze-out stage” in dense cores. In the present study we demonstrate that a similar mechanism results in the formation of the biologically relevant molecule glycerol—HOCH{sub 2}CH(OH)CH{sub 2}OH—a three-carbon-bearing sugar alcohol necessary for the formation of membranes of modern living cells and organelles. Our experimental results are fully consistent with a suggested reaction scheme in which glycerol is formed along a chain of radical–radical and radical–molecule interactions between various reactive intermediates produced upon hydrogenation of CO ice or its hydrogenation products. The tentative identification of the chemically related simple sugar glyceraldehyde—HOCH{sub 2}CH(OH)CHO—is discussed as well. These new laboratory findings indicate that the proposed reaction mechanism holds much potential to form even more complex sugar alcohols and simple sugars.

Anti-icing/frosting and self-cleaning performance of superhydrophobic aluminum alloys

Science.gov (United States)

Feng, Libang; Yan, Zhongna; Shi, Xueting; Sultonzoda, Firdavs

2018-02-01

Ice formation and frost deposition on cryogenic equipment and systems can result in serious problems and huge economic loss. Hence, it is quite necessary to develop new materials to prevent icing and frosting on cold surfaces in engineering fields. Here, a superhydrophobic aluminum alloy with enhanced anti-frosting, anti-icing, and self-cleaning performance has been developed by a facile one-step method. The anti-frosting/icing performance of superhydrophobic aluminum alloys is confirmed by frosting/icing time delay, consolidating and freezing temperature reduction, and lower amount of frost/ice adhesion. Meanwhile, the excellent self-cleaning performance is authenticated by the fact that simulated pollution particles can be cleaned out by rolling water droplets completely. Finally, based on the classical nucleation theory, anti-icing and anti-frosting mechanisms of the superhydrophobic aluminum alloys are deduced. Results show that grounded on "air cushion" and "heat insulation" effect, a larger nucleation barrier and a lower crystal growth rate can be observed, which, hence, inhibit ice formation and frost deposition. It can be concluded that preparing superhydrophobic surfaces would be an effective strategy for improving anti-icing, anti-frosting, and self-cleaning performance of aluminum alloys.

Fast fluorometric flow injection analysis of formaldehyde in atmospheric water

Energy Technology Data Exchange (ETDEWEB)

Dong, S.; Dasgupta, P.K.

1987-06-01

Formaldehyde can be determined in aqueous solution at a rate of 45 samples/h with a small sample requirement (100 ..mu..L). The fluorescence of 3,5-diacetyl-1,4-dihydrolutidine formed upon reaction of formaldehyde with ammonium acetate and 2,4-pentanedione (25 s, 95 /sup 0/C) is monitored with a filter fluorometer. The detection limit is 0.1 ..mu..M (3 ..mu..g/L) or 10 pmol of HCHO. The response is linear up to 3.3 ..mu..M (100 ..mu..g/L), the departure from linearity at 0.33 mM is 21%, but high levels are satisfactorily determined with a second-order calibration equation. Interference from S(IV) has been investigated in detail and completely eliminated by addition of H/sub 2/O/sub 2/ before rendering the sample alkaline. There are no effects from commonly occurring metal ions and anions; the method is very selective to formaldehyde compared to other carbonyl compounds. A S(IV)-containing preservative has been formulated for the stabilization of low concentrations of HCHO. Results are presented for fogwater samples. 8 figures, 41 references.

Highly Conductive Carbon Fiber Reinforced Concrete for Icing Prevention and Curing.

Science.gov (United States)

Galao, Oscar; Bañón, Luis; Baeza, Francisco Javier; Carmona, Jesús; Garcés, Pedro

2016-04-12

This paper aims to study the feasibility of highly conductive carbon fiber reinforced concrete (CFRC) as a self-heating material for ice formation prevention and curing in pavements. Tests were carried out in lab ambient conditions at different fixed voltages and then introduced in a freezer at -15 °C. The specimens inside the freezer were exposed to different fixed voltages when reaching +5 °C for prevention of icing and when reaching the temperature inside the freezer, i.e. , -15 °C, for curing of icing. Results show that this concrete could act as a heating element in pavements with risk of ice formation, consuming a reasonable amount of energy for both anti-icing (prevention) and deicing (curing), which could turn into an environmentally friendly and cost-effective deicing method.

The Formation each Winter of the Circumpolar Wave in the Sea Ice around Antarctica

Science.gov (United States)

Gloersen, Per; White, Warren B.

1999-01-01

Seeking to improve upon the visualization of the Antarctic Circumpolar Wave (ACW) , we compare a 16-year sequence of 6-month winter averages of Antarctic sea ice extents and concentrations with those of adjacent sea surface temperatures (SSTs). Here we follow SSTs around the globe along the maximum sea ice edge rather than in a zonal band equatorward of it. The results are similar to the earlier ones, but the ACWs do not propagate with equal amplitude or speed. Additionally in a sequence of 4 polar stereographic plots of these SSTs and sea ice concentrations, we find a remarkable correlation between SST minima and sea ice concentration maxima, even to the extent of matching contours across the ice-sea boundary, in the sector between 900E and the Palmer Peninsula. Based on these observations, we suggest that the memory of the ACW in the sea ice is carried from one Austral winter to the next by the neighboring SSTS, since the sea ice is nearly absent in the Austral summer.

Formation and High-order Carboxylic Acids (RCOOH) in Interstellar Analogous Ices of Carbon Dioxide (CO2) and Methane(CH4)

Science.gov (United States)

Zhu, Cheng; Turner, Andrew M.; Abplanalp, Matthew J.; Kaiser, Ralf I.

2018-01-01

This laboratory study simulated the abiotic formation of carboxylic acids (RCOOH) in interstellar analogous ices of carbon dioxide (CO2) and methane (CH4) at 10 K upon exposure to energetic electrons. The chemical processing of the ices and the subsequent warm-up phase were monitored online and in situ, exploiting Fourier Transform Infrared Spectrometry and quadrupole mass spectrometry. Characteristic absorptions of functional groups of carboxylic acids (RCOOH) were observed in the infrared spectra of the irradiated ice. Two proposed reaction mechanisms replicated the kinetic profiles of the carboxylic acids along with the decay profile of the precursors during the irradiation via hydrocarbon formation, followed by carboxylation and/or through acetic acid along with mass growth processes of the alkyl chain. Mass spectra recorded during the warm-up phase demonstrated that these acids are distributed from acetic acid (CH3COOH) up to decanoic acid (C9H19COOH). High-dose irradiation studies (91 ± 14 eV) converted low-molecular-weight acids such as acetic acid (CH3COOH) and propionic acid (C2H5COOH) to higher-molecular-weight carboxylic acids, compared to low-dose irradiation studies (18 ± 3 eV). The traces of the {{{H}}}2{{C}}= {{C}}({OH}{)}2+ (m/z = 60) fragment—a link to linear carboxylic acids—implied that higher-order acids (C n H2n+1COOH, n ≥ 5) are likely branched, which correlates with the recent analysis of the structures of the monocarboxylic acids in the Murchison meteorite.

Solid phase microextraction method development for measuring Henry's Law constants of formaldehyde in aqueous solutions

Science.gov (United States)

Formaldehyde (HCHO) has been of special concern as an indoor air pollutant because of its existence in a wide range of products and its adverse health effects. The air-water partitioning behavior of volatile organic compounds (VOCs) such as formaldehyde is an important process th...

Janus effect of antifreeze proteins on ice nucleation.

Science.gov (United States)

Liu, Kai; Wang, Chunlei; Ma, Ji; Shi, Guosheng; Yao, Xi; Fang, Haiping; Song, Yanlin; Wang, Jianjun

2016-12-20

The mechanism of ice nucleation at the molecular level remains largely unknown. Nature endows antifreeze proteins (AFPs) with the unique capability of controlling ice formation. However, the effect of AFPs on ice nucleation has been under debate. Here we report the observation of both depression and promotion effects of AFPs on ice nucleation via selectively binding the ice-binding face (IBF) and the non-ice-binding face (NIBF) of AFPs to solid substrates. Freezing temperature and delay time assays show that ice nucleation is depressed with the NIBF exposed to liquid water, whereas ice nucleation is facilitated with the IBF exposed to liquid water. The generality of this Janus effect is verified by investigating three representative AFPs. Molecular dynamics simulation analysis shows that the Janus effect can be established by the distinct structures of the hydration layer around IBF and NIBF. Our work greatly enhances the understanding of the mechanism of AFPs at the molecular level and brings insights to the fundamentals of heterogeneous ice nucleation.

'Real-world' compensatory behaviour with low nicotine concentration e-liquid: subjective effects and nicotine, acrolein and formaldehyde exposure.

Science.gov (United States)

Dawkins, Lynne; Cox, Sharon; Goniewicz, Maciej; McRobbie, Hayden; Kimber, Catherine; Doig, Mira; Kośmider, Leon

2018-06-07

To compare the effects of i) high versus low nicotine concentration e-liquid, ii) fixed versus adjustable power and iii) the interaction between the two on: a) vaping behaviour, b) subjective effects, c) nicotine intake, and d) exposure to acrolein and formaldehyde in e-cigarette users vaping in their everyday setting. Counterbalanced, repeated measures with four conditions: i) low nicotine (6 mg/mL)/fixed power; ii) low nicotine/adjustable power; iii) high nicotine (18 mg/mL)/fixed power; iv) high nicotine/adjustable power. London and the South East, England. Twenty experienced e-cigarette users (recruited between September 2016 and February 2017) vaped ad libitum using an eVic Supreme™ with a 'Nautilus Aspire' tank over four weeks (one week per condition). Puffing patterns (daily puff number [PN], puff duration [PD], inter-puff interval [IPI]), mL of e-liquid consumed, changes to power (where permitted), and subjective effects (urge to vape, nicotine withdrawal symptoms) were measured in each condition. Nicotine intake was measured via salivary cotinine. 3-hydroxypropylmercapturic acid (3-HPMA), a metabolite of the toxicant acrolein, and formate, a metabolite of the carcinogen formaldehyde, were measured in urine. There was a significant nicotine concentration x power interaction for PD (p<0.01). PD was longer with low nicotine/fixed power compared with i) high nicotine/fixed power (p< 0.001 and ii) low nicotine/adjustable power (p< 0.01). PN and liquid consumed were higher in the low versus high nicotine condition (main effect of nicotine, p<0.05). Urge to vape and withdrawal symptoms were lower, and nicotine intake was higher, in the high nicotine condition (main effects of nicotine: p<0.01). Whilst acrolein levels did not differ, there was a significant nicotine x power interaction for formaldehyde (p<0.05). Use of a lower nicotine concentration e-liquid may be associated with compensatory behaviour (e.g., higher number and duration of puffs) and increases

Mechanisms of basal ice formation in polar glaciers: An evaluation of the apron entrainment model

Science.gov (United States)

Fitzsimons, Sean; Webb, Nicola; Mager, Sarah; MacDonell, Shelley; Lorrain, Regi; Samyn, Denis

2008-06-01

Previous studies of polar glaciers have argued that basal ice can form when these glaciers override and entrain ice marginal aprons that accumulate adjacent to steep ice cliffs. To test this idea, we have studied the morphology, structure, composition, and deformation of the apron and basal ice at the terminus of Victoria Upper Glacier in the McMurdo dry valleys, which are located on the western coast of the Ross Sea at 77°S in southern Victoria Land, Antarctica. Our results show that the apron has two structural elements: an inner element that consists of strongly foliated ice that has a steep up-glacier dip, and an outer element that lacks a consistent foliation and has a down-glacier, slope-parallel dip. Although strain measurements show that the entire apron is deforming, the inner element is characterized by high strain rates, whereas relatively low rates of strain characterize the outer part of the apron. Co-isotopic analyses of the ice, together with analysis of solute chemistry and sedimentary characteristics, show that the apron is compositionally different from the basal ice. Our observations show that aprons may become deformed and partially entrained by advancing glaciers. However, such an ice marginal process does not provide a satisfactory explanation for the origin of basal ice observed at the ice margin. Our interpretation of the origin of basal ice is that it is formed by subglacial processes, which are likely to include deformation and entrainment of subglacial permafrost.

Interannual Variability of the Sea-Ice-Induced Salt Flux in the Greenland Sea

DEFF Research Database (Denmark)

Pedersen, Leif Toudal; Coon, M.D.

2001-01-01

The Greenland Sea is one of the few places in the World Ocean where deep convection takes place. The convection process is initiated by a density increase originating from rapid cooling and/or a salt flux to the upper layer of the ocean due to brine rejection from ice formation (Rudels, 1990......; Visbeck and others, 1995). The predominant ice types in the Greenland Sea arc frazil/grease ice and pancake ice. A numerical model has been developed relating ice formation and decay of these ice types as observed by the SMMR and SSM/I microwave radiometers and evaluating their contribution to salt...... redistribution in the Greenland Sea. The model has been used to calculate spatial distribution of the annual integrated net salt flux to the Greenland Sea from ice production and advection for the period 1979-97....

A Reagentless Amperometric Formaldehyde-Selective Chemosensor Based on Platinized Gold Electrodes.

Science.gov (United States)

Demkiv, Olha; Smutok, Oleh; Gonchar, Mykhailo; Nisnevitch, Marina

2017-05-06

Fabrication and characterization of a new amperometric chemosensor for accurate formaldehyde analysis based on platinized gold electrodes is described. The platinization process was performed electrochemically on the surface of 4 mm gold planar electrodes by both electrolysis and cyclic voltamperometry. The produced electrodes were characterized using scanning electron microscopy and X-ray spectral analysis. Using a low working potential (0.0 V vs. Ag/AgCl) enabled an essential increase in the chemosensor's selectivity for the target analyte. The sensitivity of the best chemosensor prototype to formaldehyde is uniquely high (28180 A·M -1 ·m -2 ) with a detection limit of 0.05 mM. The chemosensor remained stable over a one-year storage period. The formaldehye-selective chemosensor was tested on samples of commercial preparations. A high correlation was demonstrated between the results obtained by the proposed chemosensor, chemical and enzymatic methods ( R = 0.998). The developed formaldehyde-selective amperometric chemosensor is very promising for use in industry and research, as well as for environmental control.

Chlorine-containing salts as water ice nucleating particles on Mars

Science.gov (United States)

Santiago-Materese, D. L.; Iraci, L. T.; Clapham, M. E.; Chuang, P. Y.

2018-03-01

Water ice cloud formation on Mars largely is expected to occur on the most efficient ice nucleating particle available. Salts have been observed on the Martian surface and have been known to facilitate water cloud formation on Earth. We examined heterogeneous ice nucleation onto sodium chloride and sodium perchlorate substrates under Martian atmospheric conditions, in the range of 150 to 180 K and 10-7 to 10-5 Torr water partial pressure. Sub-155 K data for the critical saturation ratio (Scrit) suggests an exponential model best describes the temperature-dependence of nucleation onset of water ice for all substrates tested. While sodium chloride does not facilitate water ice nucleation more easily than bare silicon, sodium perchlorate does support depositional nucleation at lower saturation levels than other substrates shown and is comparable to smectite-rich clay in its ability to support cloud initiation. Perchlorates could nucleate water ice at partial pressures up to 40% lower than other substrates examined to date under Martian atmospheric conditions. These findings suggest air masses on Mars containing uplifted salts such as perchlorates could form water ice clouds at lower saturation ratios than in air masses absent similar particles.

75 FR 37792 - Formaldehyde Gas; Receipt of Application for Emergency Exemption, Solicitation of Public Comment

Science.gov (United States)

2010-06-30

... Emergency Management, Office of Solid Waste and Emergency Response (OSWER) to use formaldehyde gas (CAS No... American Industrial Classification System (NAICS) codes have been provided to assist you and others in... ENVIRONMENTAL PROTECTION AGENCY [EPA-HQ-OPP-2010-0420; FRL-8828-9] Formaldehyde Gas; Receipt of...

Dynamical Upheaval in Ice Giant Formation: A Solution to the Fine-tuning Problem in the Formation Story

Science.gov (United States)

Frelikh, Renata; Murray-Clay, Ruth

2018-04-01

We report on our recent theoretical work, where we suggest that a protoplanetary disk dynamical instability may have played a crucial role in determining the atmospheric size of the solar system’s ice giants. In contrast to the gas giants, the intermediate-size ice giants never underwent runaway gas accretion in a full gas disk. However, as their substantial core masses are comparable to those of the gas giants, they would have gone runaway, given enough time. In the standard scenario, the ice giants stay at roughly their current size for most of the disk lifetime, undergoing period of slow gas accretion onto ~full-sized cores that formed early-on. The gas disk dissipates before the ice giants accumulate too much gas, but we believe this is fine tuned. A considerable amount of solids is observed in outer disks in mm-to-cm sized particles (pebbles). Assisted by gas drag, these pebbles rapidly accrete onto cores. This would cause the growing ice giants to exceed their current core masses, and quickly turn into gas giants. To resolve this problem, we propose that Uranus and Neptune stayed small for the bulk of the disk lifetime. They only finished their core and atmospheric growth in a short timeframe just as the disk gas dissipated, accreting most of their gas from a disk depleted to ~1% of its original mass. The ice giants have atmospheric mass fractions comparable to the disk gas-to-solid ratio of this depleted disk. This coincides with a disk dynamical upheaval onset by the depletion of gas. We propose that the cores started growing closer-in, where they were kept small by proximity to Jupiter and Saturn. As the gas cleared, the cores were kicked out by the gas giants. Then, they finished their core growth and accreted their atmospheres from the remaining, sparse gas at their current locations. We predict that the gas giants may play a key role in forming intermediate-size atmospheres in the outer disk.

FORMATION OF N{sub 3}, CH{sub 3}, HCN, AND HNC FROM THE FAR-UV PHOTOLYSIS OF CH{sub 4} IN NITROGEN ICE

Energy Technology Data Exchange (ETDEWEB)

Lo, Jen-Iu; Chou, Sheng-Lung; Peng, Yu-Chain; Lin, Meng-Yeh; Lu, Hsiao-Chi; Cheng, Bing-Ming, E-mail: bmcheng@nsrrc.org.tw [National Synchrotron Radiation Research Center, No. 101, Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan (China)

2015-11-15

The irradiation of pure solid N{sub 2} at 3 K with far-ultraviolet light from a synchrotron produced infrared absorption lines at 1657.7, 1655.6, and 1652.4 cm{sup −1} and an ultraviolet absorption line at 272.0 nm, which are characteristic of the product N{sub 3}. The threshold wavelength at which N{sub 3} was generated was 145.6 ± 2.9 nm, corresponding to an energy of 8.52 ± 0.17 eV. The photolysis of isotopically labeled {sup 15}N{sub 2} at 3 K consistently led to the formation of {sup 15}N{sub 3} with the same threshold wavelength of 145.6 ± 2.9 nm for its formation. The photolysis of CH{sub 4} in nitrogen ice in low concentrations also led to the formation of N{sub 3}, together with CH{sub 3}, HCN, and HNC, with the same threshold wavelength of 145.6 ± 2.9 nm. These results indicate that N{sub 3} radicals may play an important role in the photochemistry of nitrogen ices in astronomical environments.

Synthesis and Structure Characterization of Phenol-Urea-Formaldehyde Resins in the Presence of Magnesium Oxide as Catalyst

Directory of Open Access Journals (Sweden)

Dong-Bin Fan

2014-08-01

Full Text Available The objective of this research was to provide a useful approach of polymer synthesis for accelerating the fast cure of phenol-urea-formaldehyde (PUF resin as wood adhesive by optimizing its structure and composition. The PUF resins containing high contents of very reactive groups such as para-methylol groups were synthesized by reacting methylolurea, phenol, and formaldehyde in the presence of magnesium oxide (MgO as catalyst. The effects of synthesis parameters including F/(P + U, OH/P, and MgO/P mole ratios on the structure, composition, curing characteristics, and their relationships of PUF resins were investigated. The results indicated that MgO seemed to be an efficacious catalyst for PUF resin synthesis and promote its faster cure. The increase in the F/(P + U mole ratio or/and OH/P mole ratio appeared to be beneficial for the formation of para-methylol groups and cocondensed methylene linkages between phenolic methylol groups and urea units, and for the removal of unreacted urea. In case of Catalyst/P mole ratio, an appropriate dosage of added metal-ion was very important for synthesizing the high-content reactive groups of PUF resins, otherwise leading to the reverse effects.

Highly Conductive Carbon Fiber Reinforced Concrete for Icing Prevention and Curing

Directory of Open Access Journals (Sweden)

Oscar Galao

2016-04-01

Full Text Available This paper aims to study the feasibility of highly conductive carbon fiber reinforced concrete (CFRC as a self-heating material for ice formation prevention and curing in pavements. Tests were carried out in lab ambient conditions at different fixed voltages and then introduced in a freezer at −15 °C. The specimens inside the freezer were exposed to different fixed voltages when reaching +5 °C for prevention of icing and when reaching the temperature inside the freezer, i.e., −15 °C, for curing of icing. Results show that this concrete could act as a heating element in pavements with risk of ice formation, consuming a reasonable amount of energy for both anti-icing (prevention and deicing (curing, which could turn into an environmentally friendly and cost-effective deicing method.

"Greener" hybrid adhesives composed of urea formaldehyde resin and cottonseed meal for wood based composites

Science.gov (United States)

Urea formaldehyde (UF) resins are one of the most widely used adhesives in wood based composites. The major concerns of the resin utilization are free formaldehyde release and poor water resistance. As a renewable raw materials, water washed conttonseed meal can be used in wood bonding. To produce “...

Influence of indoor formaldehyde pollution on respiratory system ...

African Journals Online (AJOL)

Some adults surveyed complained of common respiratory system disorders, including coughing (11.8%), nasal irritation (39.2%), Heterosmia (14.51%), and throat irritation (25.27%); 12% of children suffered from asthma. The analysis identified formaldehyde pollution and ventilation frequency as risk factors for respiratory ...

A biodegradable colorimetric film for rapid low-cost field determination of formaldehyde contamination by digital image colorimetry.

Science.gov (United States)

Wongniramaikul, Worawit; Limsakul, Wadcharawadee; Choodum, Aree

2018-05-30

A biodegradable colorimetric film was fabricated on the lid of portable tube for in-tube formaldehyde detection. Based on the entrapment of colorimetric reagents within a thin film of tapioca starch, the yellow reaction product was observed with formaldehyde. Intensity of the blue channel from the digital image of yellow product showed a linear relationship in the range of 0-25 mg L -1 with low detection limit of 0.7 ± 0.1 mg L -1 . Inter-day precision of 0.61-3.10%RSD were obtained with less than 4.2% relative error from control samples. The developed method was applied for various food samples in Phuket and formaldehyde concentration range was non-detectable to 1.413 mg kg -1 . The quantified concentrations of formaldehyde in fish and squid samples provided relative errors of -7.7% and +10.8% compared to spectrophotometry. This low cost sensor (∼0.04 USD/test) with digital image colorimetry was thus an effective alternative for formaldehyde detection in food sample. Copyright © 2018 Elsevier Ltd. All rights reserved.

FORMALDEHYDE GAS INACTIVATION OF BACILLUS ANTHRACIS, BACILLUS SUBTILIS AND GEOBACILLUS STEAROTHERMOPHILUS SPORES ON INDOOR SURFACE MATERIALS.

Science.gov (United States)

Research evaluated the decontamination of Bacillus anthracis, Bacillus subtilis, and Geobacillus stearothermophilus spores on indoor surface material using formaldehyde gas. Spores were dried on seven types of indoor surfaces and exposed to 1100 ppm formaldehyde gas for 10 hr. Fo...

Pd-Cu/poly(o-Anisidine) nanocomposite as an efficient catalyst for formaldehyde oxidation

Energy Technology Data Exchange (ETDEWEB)

Hosseini, Sayed Reza, E-mail: r.hosseini@umz.ac.ir [Nanochemistry Research Laboratory, Faculty of Chemistry, University of Mazandaran, 47416-95447 Babolsar (Iran, Islamic Republic of); Raoof, Jahan-Bakhsh [Department of Analytical Chemistry, Faculty of Chemistry, University of Mazandaran, 47416-95447 Babolsar (Iran, Islamic Republic of); Ghasemi, Shahram; Gholami, Zahra [Nanochemistry Research Laboratory, Faculty of Chemistry, University of Mazandaran, 47416-95447 Babolsar (Iran, Islamic Republic of)

2016-08-15

Highlights: • o-Anisidine monomer was electro-polymerized at the pCPE surface in acid medium. • Palladium/copper NPs were prepared by galvanic replacement method at the POA/pCPE. • Pd-Cu NPs showed excellent electrocatalytic activity towards formaldehyde oxidation. • The bimetallic Pd-Cu NPs/POA nanocomposite showed satisfactory long-term stability. - Abstract: In this work, for the first time, the electrocatalytic oxidation of formaldehyde in 0.5 M sulfuric acid solution at spherical bimetallic palladium-copper nanoparticles (Pd-Cu NPs) deposited on the poly (o-Anisidine) film modified electrochemically pretreated carbon paste electrode (POA/pCPE) has been investigated. Highly porous POA film prepared by electropolymerization onto the pCPE was used as a potent support for deposition of the Pd-Cu NPs. The Pd-Cu NPs were prepared through spontaneous and irreversible reaction via galvanic replacement between Pd{sup II} ions and the Cu{sup 0} particles. The prepared Pd-Cu NPs were characterized by scanning electron microscopy, energy dispersive spectroscopy and electrochemical methods. The obtained results showed that the utilization of Cu nanoparticles and pretreatment technique enhances the electrocatalytic activity of the modified electrode towards formaldehyde oxidation. The influence of several parameters on formaldehyde oxidation as well as stability of the Pd-Cu/POA/pCPE has been investigated.

Possible significance of cubic water-ice, H2O-Ic, in the atmospheric water cycle of Mars

Science.gov (United States)

Gooding, James L.

1988-01-01

The possible formation and potential significance of the cubic ice polymorph on Mars is discussed. When water-ice crystallizes on Earth, the ambient conditions of temperature and pressure result in the formation of the hexagonal ice polymorph; however, on Mars, the much lower termperature and pressures may permit the crystallization of the cubic polymorph. Cubic ice has two properties of possible importance on Mars: it is an excellant nucleator of other volatiles (such as CO2), and it undergoes an exothermic transition to hexagonal ice at temperatures above 170 K. These properties may have significant implications for both martian cloud formation and the development of the seasonal polar caps.

Formaldehyde and acetaldehyde exposure mitigation in US residences: In-home measurements of ventilation control and source control

Energy Technology Data Exchange (ETDEWEB)

Hult, Erin L. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Willem, Henry [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Price, Phillip N. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Hotchi, Toshifumi [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Russell, Marion L. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Singer, Brett C. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2014-10-01

Measurements were taken in new US residences to assess the extent to which ventilation and source control can mitigate formaldehyde exposure. Increasing ventilation consistently lowered indoor formaldehyde concentrations. However, at a reference air exchange rate of 0.35 h^-1, increasing ventilation was up to 60% less effective than would be predicted if the emission rate were constant. This is consistent with formaldehyde emission rates decreasing as air concentrations increase, as observed in chamber studies. In contrast, measurements suggest acetaldehyde emission was independent of ventilation rate. To evaluate the effectiveness of source control, formaldehyde concentrations were measured in Leadership in Energy and Environmental Design (LEED) certified/Indoor airPLUS homes constructed with materials certified to have low emission rates of volatile organic compounds (VOC). At a reference air exchange rate of 0.35 h^-1, and adjusting for home age, temperature and relative humidity, formaldehyde concentrations in homes built with low-VOC materials were 42% lower on average than in reference new homes with conventional building materials. Without adjustment, concentrations were 27% lower in the low-VOC homes. The mean and standard deviation of formaldehyde concentration were 33 μg m-3 and 22 μg m^-3 for low-VOC homes and 45 μg m^-3 and 30 μg m^-3 for conventional.

ATM and KAT5 safeguard replicating chromatin against formaldehyde damage

Science.gov (United States)

Ortega-Atienza, Sara; Wong, Victor C.; DeLoughery, Zachary; Luczak, Michal W.; Zhitkovich, Anatoly

2016-01-01

Many carcinogens damage both DNA and protein constituents of chromatin, and it is unclear how cells respond to this compound injury. We examined activation of the main DNA damage-responsive kinase ATM and formation of DNA double-strand breaks (DSB) by formaldehyde (FA) that forms histone adducts and replication-blocking DNA-protein crosslinks (DPC). We found that low FA doses caused a strong and rapid activation of ATM signaling in human cells, which was ATR-independent and restricted to S-phase. High FA doses inactivated ATM via its covalent dimerization and formation of larger crosslinks. FA-induced ATM signaling showed higher CHK2 phosphorylation but much lower phospho-KAP1 relative to DSB inducers. Replication blockage by DPC did not produce damaged forks or detectable amounts of DSB during the main wave of ATM activation, which did not require MRE11. Chromatin-monitoring KAT5 (Tip60) acetyltransferase was responsible for acetylation and activation of ATM by FA. KAT5 and ATM were equally important for triggering of intra-S-phase checkpoint and ATM signaling promoted recovery of normal human cells after low-dose FA. Our results revealed a major role of the KAT5-ATM axis in protection of replicating chromatin against damage by the endogenous carcinogen FA. PMID:26420831

Formaldehyde as a carbon and electron shuttle between autotroph and heterotroph populations in acidic hydrothermal vents of Norris Geyser Basin, Yellowstone National Park

Energy Technology Data Exchange (ETDEWEB)

Moran, James J.; Whitmore, Laura M.; Isern, Nancy G.; Romine, Margaret F.; Riha, Krystin M.; Inskeep, William P.; Kreuzer, Helen W.

2016-03-19

The Norris Geyser Basin in Yellowstone National Park contains a large number of hydrothermal systems, which host microbial populations supported by primary productivity associated with a suite of chemolithotrophic metabolisms. We demonstrate that Metallosphaera yellowstonesis MK1, a facultative autotrophic archaeon isolated from a hyperthermal acidic hydrous ferric oxide (HFO) spring in Norris Geyser Basin, excretes formaldehyde during autotrophic growth. To determine the fate of formaldehyde in this low organic carbon environment, we incubated native microbial mat (containing M. yellowstonensis) from a HFO spring with 13C-formaldehyde. Isotopic analysis of incubation-derived CO2 and biomass showed that formaldehyde was both oxidized and assimilated by members of the community. Autotrophy, formaldehyde oxidation, and formaldehyde assimilation displayed different sensitivities to chemical inhibitors, suggesting that distinct sub-populations in the mat selectively perform these functions. Our results demonstrate that electrons originally resulting from iron oxidation can energetically fuel autotrophic carbon fixation and associated formaldehyde excretion, and that formaldehyde is both oxidized and assimilated by different organisms within the native microbial community. Thus, formaldehyde can effectively act as a carbon and electron shuttle connecting the autotrophic, iron oxidizing members with associated heterotrophic members in the HFO community.

Synthesis of morphology-controlled carbon hollow particles by carbonization of resorcinol-formaldehyde precursor microspheres and applications in lithium-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Zhang Haijiao, E-mail: seaboyfang@163.com [Modern Manufacture Engineering Center, Heilongjiang Institute of Science and Technology, 150027 (China); Xu Huifang, E-mail: xuhf@hit.edu.cn [School of Chemical Engineering and Technology, Harbin Institute of Technology, 150001 (China); Zhao Can [Modern Manufacture Engineering Center, Heilongjiang Institute of Science and Technology, 150027 (China)

2012-03-15

Highlights: Black-Right-Pointing-Pointer Resorcinol-formaldehyde hollow particles could be obtained by inverse suspension method. Black-Right-Pointing-Pointer The morphologies of RF carbon precursor particles could be controlled by adjusting the pH values of the RF precursor. Black-Right-Pointing-Pointer The prepared carbon hollow particles, which derived from resorcinol-formaldehyde, exhibited microporous properties. Black-Right-Pointing-Pointer The RF carbon microcapsules displayed excellent power property and cycle durability. - Abstract: The morphology-controlled carbon hollow particles, derived from resorcinol-formaldehyde (RF) particles, were prepared by using an (oil phase) O/(water phase) W/(oil phase) O inverse-emulsion system which was formed by adding RF precursor (water phase) to n-hexane (oil phase) with Span-80 as surfactant and the following carbonization. This simple method led to the formation of various morphologies of RF carbon precursor particles such as hollow spheres, bowl-like hollow structures, microcapsules, or solid microspheres by adjusting the pH values of the RF precursor. The synthesized carbon particles exhibited porous characters with the surface area of 659 m{sup 2} g{sup -1} and the total pore volume of 0.44 cm{sup 3} g{sup -1}. Additionally, the electrochemical behavior of the typical RF carbon particles in lithium-ion batteries revealed that the RF carbon microcapsules displayed a high initial discharge capacity of 1059 mAh g{sup -1} and stabilized at about 330 mAh g{sup -1}, indicating its excellent power property and cycle durability.

Formaldehyde and acetaldehyde emissions from residential wood combustion in Portugal

Science.gov (United States)

Cerqueira, Mário; Gomes, Luís; Tarelho, Luís; Pio, Casimiro

2013-06-01

A series of experiments were conducted to characterize formaldehyde and acetaldehyde emissions from residential combustion of common wood species growing in Portugal. Five types of wood were investigated: maritime pine (Pinus pinaster), eucalyptus (Eucalyptus globulus), cork oak (Quercus suber), holm oak (Quercus rotundifolia) and pyrenean oak (Quercus pyrenaica). Laboratory experiments were performed with a typical wood stove used for domestic heating in Portugal and operating under realistic home conditions. Aldehydes were sampled from diluted combustion flue gas using silica cartridges coated with 2,4-dinitrophenylhydrazine and analyzed by high performance liquid chromatography with diode array detection. The average formaldehyde to acetaldehyde concentration ratio (molar basis) in the stove flue gas was in the range of 2.1-2.9. Among the tested wood types, pyrenean oak produced the highest emissions for both formaldehyde and acetaldehyde: 1772 ± 649 and 1110 ± 454 mg kg-1 biomass burned (dry basis), respectively. By contrast, maritime pine produced the lowest emissions: 653 ± 151 and 371 ± 162 mg kg-1 biomass (dry basis) burned, respectively. Aldehydes were sampled separately during distinct periods of the holm oak wood combustion cycles. Significant variations in the flue gas concentrations were found, with higher values measured during the devolatilization stage than in the flaming and smoldering stages.

A Potentiometric Formaldehyde Biosensor Based on Immobilization of Alcohol Oxidase on Acryloxysuccinimide-modified Acrylic Microspheres

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Lee Yook Heng

2010-11-01

Full Text Available A new alcohol oxidase (AOX enzyme-based formaldehyde biosensor based on acrylic microspheres has been developed. Hydrophobic poly(n-butyl acrylate-N-acryloxy-succinimide [poly(nBA-NAS] microspheres, an enzyme immobilization matrix, was synthesized using photopolymerization in an emulsion form. AOX-poly(nBA-NAS microspheres were deposited on a pH transducer made from a layer of photocured and self-plasticized polyacrylate membrane with an entrapped pH ionophore coated on a Ag/AgCl screen printed electrode (SPE. Oxidation of formaldehyde by the immobilized AOX resulted in the production of protons, which can be determined via the pH transducer. Effects of buffer concentrations, pH and different amount of immobilization matrix towards the biosensor’s analytical performance were investigated. The formaldehyde biosensor exhibited a dynamic linear response range to formaldehyde from 0.3–316.2 mM and a sensitivity of 59.41 ± 0.66 mV/decade (R2 = 0.9776, n = 3. The lower detection limit of the biosensor was 0.3 mM, while reproducibility and repeatability were 3.16% RSD (relative standard deviation and 1.11% RSD, respectively (n = 3. The use of acrylic microspheres in the potentiometric formaldehyde biosensor improved the biosensor’s performance in terms of response time, linear response range and long term stability when compared with thick film immobilization methods.