Temporal and Spatial Scales of Labrador Sea Water Formation

Science.gov (United States)

Clarke, R. A.

1984-01-01

Labrador Sea Water is an intermediate water found at the same density and depth range in the North Atlantic as the Mediterranean water. It is formed by convection from the sea surface to depths greather than 2 km in winter in the Western Labrador Sea. The processes leading to deep convection begin with the formation of a 200 km scale cyclonic circulation about denser than average upper layer water in the Western Labrador Sea. This circulation pattern is hypothesized to be driven by an ocean/atmosphere heat exchange that has its maximum in this region. By early March, if deep convection is taking place, one sees that this body of denser upper waters penetrates to the top of the deep temperature/salinity maximum marking the core of the North Atlantic Deep Water. We note that the horizontal scale of this body is still 100-200 km normal to the coastline.

Development of the North Pacific Ocean model for the assessment of the distribution of the radioactive materials. Improvement for formation of the North Pacific intermediate water

International Nuclear Information System (INIS)

Tsubono, Takaki; Misumi, Kazuhiro; Tsumune, Daisuke; Bryan, Frank

2014-01-01

The radioactive materials such as 137 Cs were released to the North Pacific Ocean (NP) through the major pathway; direct release from the accident site and atmospheric deposition, after the accidents at the Fukushima Dai-ichi Nuclear Power Plant following the earthquake and tsunami. The behavior of the materials in the NP has been paid great attention after the accident. The North Pacific Model for the calculation of the distribution of radionuclides has been developed using Regional Ocean Modeling System (ROMS). The model domain is NP with an eddy-resolving grid. A series of numerical experiments conducted by models suggests that the computational diffusivity caused by the advection scheme and the topography roughness are critical in representing the separation of Kuroshio, the Kuroshio Extension, the mixed-water region between Kuroshio Extension and Oyashio front and the formation of the North Pacific Intermediate Water (NPIW). The model requires the forth order scheme in the tracer advection and the smoothing of topography for these problems. Moreover the tidal mixing process around the straits in the North Pacific Ocean and the sea ice play important roles to reproduce the formation of lon salinity around the NPIW as well as the isopycnal mixing process represented by an eddy-resolving model. (author)

Kinetics of formation of acrylamide and Schiff base intermediates from asparagine and glucose

DEFF Research Database (Denmark)

Hedegaard, Rikke Susanne Vingborg; Frandsen, Henrik; Skibsted, Leif H.

2008-01-01

From the concentration of glucose and asparagine as reactants and of acrylamide as product each determined by LC-MS during reaction in an acetonitrile/water (68:32) model system at pH 7.6 (0.04 M phosphate buffer) and from the relative concentration of the Schiff base intermediate, the decarboxyl......From the concentration of glucose and asparagine as reactants and of acrylamide as product each determined by LC-MS during reaction in an acetonitrile/water (68:32) model system at pH 7.6 (0.04 M phosphate buffer) and from the relative concentration of the Schiff base intermediate...

Interaction of the Faroe Bank Channel overflow with Iceland Basin intermediate waters

Science.gov (United States)

Ullgren, Jenny E.; Fer, Ilker; Darelius, Elin; Beaird, Nicholas

2014-01-01

The narrow and deep Faroe Bank Channel (FBC) is an important pathway for cold, dense waters from the Nordic Seas to flow across the Iceland-Scotland ridge into the North Atlantic. The swift, turbulent FBC overflow is associated with strong vertical mixing. Hydrographic profiles from a shipboard survey and two Slocum electric gliders deployed during a cruise in May-June 2012 show an intermediate water mass characterized by low salinity and low oxygen concentration between the upper waters of Atlantic origin and the dense overflow water. A weak low-salinity signal originating north-east of Iceland is discernible at the exit of the FBC, but smeared out by intense mixing. Further west (downstream) marked salinity and oxygen minima are found, which we hypothesize are indicators of a mixture of Labrador Sea Water and Intermediate Water from the Iceland Basin. Water mass characteristics vary strongly on short time scales. Low-salinity, low-oxygen water in the stratified interface above the overflow plume is shown to move along isopycnals toward the Iceland-Faroe Front as a result of eddy stirring and a secondary, transverse circulation in the plume interface. The interaction of low-salinity, low-oxygen intermediate waters with the overflow plume already at a short distance downstream of the sill, here reported for the first time, affects the final properties of the overflow waters through entrainment and mixing.

Evaluation of trace organic contaminants in ultra-pure water production processes by measuring total organic halogen formation potential

International Nuclear Information System (INIS)

Urano, Kohei; Iwase, Yoko

1984-01-01

A new procedure for the determination of organic substances in water with high accuracy and high sensitivity was proposed, in which a hypochlorite is added to water, and the resultant total amount of organic halogen compounds (TOX formation potential) was measured, and it was applied to the evaluation of trace organic contaminants in ultra-pure water production process. In this investigation, the TOX formation potential of the raw water which was to be used for the ultra-pure water production process, intermediately treated water and ultra-pure water was measured to clarify the behavior of organic substances in the ultra-pure water production process and to demonstrate the usefulness of this procedure to evaluate trace organic contaminants in water. The measurement of TOX formation potential requires no specific technical skill, and only a short time, and gives accurate results, therefore, it is expected that the water quality control in the ultra-pure water production process can be performed more exactly by applying this procedure. (Yoshitake, I.)

Mode and Intermediate Waters in Earth System Models

Energy Technology Data Exchange (ETDEWEB)

Gnanadesikan, Anand [Johns Hopkins Univ., Baltimore, MD (United States); Sarmiento, Jorge L. [Princeton Univ., NJ (United States)

2015-12-22

This report describes work done as part of a joint Princeton-Johns Hopkins project to look at the impact of mode and intermediate waters in Earth System Models. The Johns Hopkins portion of this work focussed on the role of lateral mixing in ventilating such waters, with important implications for hypoxia, the uptake of anthropogenic carbon, the dynamics of El Nino and carbon pumps. The Johns Hopkins group also collaborated with the Princeton Group to help develop a watermass diagnostics framework.

Insights into North Atlantic deep water formation during the peak interglacial interval of Marine Isotope Stage 9 (MIS 9)

Science.gov (United States)

Mokeddem, Zohra; McManus, Jerry F.

2017-11-01

Foraminifera abundance and stable isotope records from ODP Site 984 (61.25°N, 24.04°W, 1648 m) in the North Atlantic are used to reconstruct surface circulation variations and the relative strength of the North Atlantic Deep Water (NADW) formation over the period spanning the peak warmth of Marine Interglacial Stage (MIS) 9e ( 324-336 ka). This interval includes the preceding deglaciation, Termination 4 (T4), and the subsequent glacial inception of MIS 9d. The records indicate a greatly reduced contribution of NADW during T4, as observed in more recent deglaciations. In contrast with the most recent deglaciation, the lack of a significant NADW signal extended from T4 well into the peak interglacial MIS 9e and persisted nearly until the transition to the subsequent glacial stage MIS 9d. Although NADW formation resumed during MIS 9e, only depths greater than 2000 m appear to have been ventilated. The poorly ventilated intermediate depth of Site 984 (<2000 m) may have resulted on one hand from a general reduction of deep water ventilation by NADW during the study interval or, on the other hand, from different pathways of the spread of newly formed NADW that bypassed the study location. The intermediate depths may have also been invaded by southern-sourced waters as the formation of intermediate depth NADW weakened. The absence of any significant NADW signal at the water depth of Site 984 during the climatic optimum contrasts sharply with subsequent interglacial peaks (MIS 5e and the Holocene). Despite the perturbed intermediate depth circulation, oceanic heat transport northeastward was not interrupted and may have contributed to the relatively mild interglacial conditions of MIS 9e.

Dynamic Scaling of Colloidal Gel Formation at Intermediate Concentrations.

Science.gov (United States)

Zhang, Qingteng; Bahadur, Divya; Dufresne, Eric M; Grybos, Pawel; Kmon, Piotr; Leheny, Robert L; Maj, Piotr; Narayanan, Suresh; Szczygiel, Robert; Ramakrishnan, Subramanian; Sandy, Alec

2017-10-27

We have examined the formation and dissolution of gels composed of intermediate volume-fraction nanoparticles with temperature-dependent short-range attractions using small-angle x-ray scattering, x-ray photon correlation spectroscopy, and rheology to obtain nanoscale and macroscale sensitivity to structure and dynamics. Gel formation after temperature quenches to the vicinity of the rheologically determined gel temperature, T_{gel}, was characterized via the slowdown of dynamics and changes in microstructure observed in the intensity autocorrelation functions and structure factor, respectively, as a function of quench depth (ΔT=T_{quench}-T_{gel}), wave vector, and formation time t_{f}. We find the wave-vector-dependent dynamics, microstructure, and rheology at a particular ΔT and t_{f} map to those at other ΔTs and t_{f}s via an effective scaling temperature, T_{s}. A single T_{s} applies to a broad range of ΔT and t_{f} but does depend on the particle size. The rate of formation implied by the scaling is a far stronger function of ΔT than expected from the attraction strength between colloids. We interpret this strong temperature dependence in terms of cooperative bonding required to form stable gels via energetically favored, local structures.

Evidence for a Shared Mechanism in the Formation of Urea-Induced Kinetic and Equilibrium Intermediates of Horse Apomyoglobin from Ultrarapid Mixing Experiments

Science.gov (United States)

Mizukami, Takuya; Abe, Yukiko; Maki, Kosuke

2015-01-01

In this study, the equivalence of the kinetic mechanisms of the formation of urea-induced kinetic folding intermediates and non-native equilibrium states was investigated in apomyoglobin. Despite having similar structural properties, equilibrium and kinetic intermediates accumulate under different conditions and via different mechanisms, and it remains unknown whether their formation involves shared or distinct kinetic mechanisms. To investigate the potential mechanisms of formation, the refolding and unfolding kinetics of horse apomyoglobin were measured by continuous- and stopped-flow fluorescence over a time range from approximately 100 μs to 10 s, along with equilibrium unfolding transitions, as a function of urea concentration at pH 6.0 and 8°C. The formation of a kinetic intermediate was observed over a wider range of urea concentrations (0–2.2 M) than the formation of the native state (0–1.6 M). Additionally, the kinetic intermediate remained populated as the predominant equilibrium state under conditions where the native and unfolded states were unstable (at ~0.7–2 M urea). A continuous shift from the kinetic to the equilibrium intermediate was observed as urea concentrations increased from 0 M to ~2 M, which indicates that these states share a common kinetic folding mechanism. This finding supports the conclusion that these intermediates are equivalent. Our results in turn suggest that the regions of the protein that resist denaturant perturbations form during the earlier stages of folding, which further supports the structural equivalence of transient and equilibrium intermediates. An additional folding intermediate accumulated within ~140 μs of refolding and an unfolding intermediate accumulated in <1 ms of unfolding. Finally, by using quantitative modeling, we showed that a five-state sequential scheme appropriately describes the folding mechanism of horse apomyoglobin. PMID:26244984

Paleoproductivity and intermediate-water ventilation in the subarctic Northwest Pacific during the last deglaciation

Science.gov (United States)

Khim, B.; Ikehara, K.; Sagawa, T.; Shibahara, A.; Yamamoto, M.

2010-12-01

Laminated sediments during the last deglaciation in the subarctic North Pacific indicate significant depletion of dissolved oxygen concentration at intermediate water depths. Such a strong oxygen minimum zone results primarily from a combination of high surface water productivity and poor ventilation of intermediate waters. We investigated a variety of paleoclimatic proxies using about 8-m long piston core sediment (GH02-1030; 42o13.770N, 144o12.530E; water depth, 1212 m) obtained from the continental slope off Tokachi (eastern Hokkaido Island), which is the main path of the southwestward Oyashio Current in the subarctic Northwest Pacific. Laminated sediments were identified at the two horizons in the core GH02-1030; the upper one at 11.4-12.2 cal.kyr BP and the lower one at 14.1-14.7 cal.kyr BP, corresponding to Bølling-Allerød (B/A) and Preboreal (PB), respectively. Between these laminated layers, Younger Dryas occurred. Both laminated sediment layers are characterized by Bolivina tumida, B. pacifica, and Buliminella tenuata, indicating dysoxic bottom water conditions. Increased Mg/Ca-derived intermediate-water temperature and δ18OW values at B/A and PB periods suggest the poor ventilation of intermediate water because of the surface water freshening (i.e., decrease of surface-water salinity). UK'37-derived temperature record also supports the increase of surface-water temperature during B/A and PB intervals. During the last deglaciation, short-chain C14-C18 n-fatty acids, derived mainly from marine organisms, showed higher concentrations, indicating the increased surface-water production, and at the same time, abundant lignin reflected more contribution of terrigenous organic matter, supporting increased freshwater discharge. Variation of CaCO3 contents show remarkable double peaks, corresponding to B/A and PB periods, respectively, leading to the increase of TOC contents. Opal contents also follow similar pattern to CaCO3 contents, but are much less than the

Different roles of water in secondary organic aerosol formation from toluene and isoprene

Science.gov (United States)

Jia, Long; Xu, YongFu

2018-06-01

Roles of water in the formation of secondary organic aerosol (SOA) from the irradiations of toluene-NO2 and isoprene-NO2 were investigated in a smog chamber. Experimental results show that the yield of SOA from toluene almost doubled as relative humidity increased from 5 to 85 %, whereas the yield of SOA from isoprene under humid conditions decreased by 2.6 times as compared to that under dry conditions. The distinct difference of RH effects on SOA formation from toluene and isoprene is well explained with our experiments and model simulations. The increased SOA from humid toluene-NO2 irradiations is mainly contributed by O-H-containing products such as polyalcohols formed from aqueous reactions. The major chemical components of SOA in isoprene-NO2 irradiations are oligomers formed from the gas phase. SOA formation from isoprene-NO2 irradiations is controlled by stable Criegee intermediates (SCIs) that are greatly influenced by water. As a result, high RH can obstruct the oligomerization reaction of SCIs to form SOA.

Mixing and remineralization in waters detrained from the surface into Subantarctic Mode Water and Antarctic Intermediate Water in the southeastern Pacific

Science.gov (United States)

Carter, B. R.; Talley, L. D.; Dickson, A. G.

2014-06-01

A hydrographic data set collected in the region and season of Subantarctic Mode Water and Antarctic Intermediate Water (SAMW and AAIW) formation in the southeastern Pacific allows us to estimate the preformed properties of surface water detrained into these water masses from deep mixed layers north of the Subantarctic Front and Antarctic Surface Water south of the front. Using 10 measured seawater properties, we estimate: the fractions of SAMW/AAIW that originate as surface source waters, as well as fractions that mix into these water masses from subtropical thermocline water above and Upper Circumpolar Deep Water below the subducted SAMW/AAIW; ages associated with the detrained surface water; and remineralization and dissolution rates and ratios. The mixing patterns imply that cabbeling can account for ˜0.005-0.03 kg m-3 of additional density in AAIW, and ˜0-0.02 kg m-3 in SAMW. We estimate a shallow depth (˜300-700 m, above the aragonite saturation horizon) calcium carbonate dissolution rate of 0.4 ± 0.2 µmol CaCO3 kg-1 yr-1, a phosphate remineralization rate of 0.031 ± 0.009 µmol P kg-1 yr-1, and remineralization ratios of P:N:-O2:Corg of 1:(15.5 ± 0.6):(143 ± 10):(104 ± 22) for SAMW/AAIW. Our shallow depth calcium carbonate dissolution rate is comparable to previous estimates for our region. Our -O2:P ratio is smaller than many global averages. Our model suggests neglecting diapycnal mixing of preformed phosphate has likely biased previous estimates of -O2:P and Corg:P high, but that the Corg:P ratio bias may have been counteracted by a second bias in previous studies from neglecting anthropogenic carbon gradients.

Origin and pathways of Winter Intermediate Water in the Northwestern Mediterranean Sea using observations and numerical simulation

Science.gov (United States)

Juza, Mélanie; Renault, Lionel; Ruiz, Simon; Tintoré, Joaquin

2013-12-01

The study of water masses worldwide (their formation, spreading, mixing, and impact on general circulation) is essential for a better understanding of the ocean circulation and variability. In this paper, the formation and main pathways of Winter Intermediate Water (WIW) in the Northwestern Mediterranean Sea (NWMED) are investigated during the winter-spring 2011 using observations and numerical simulation. The main results show that the WIW, formed along the continental shelves of the Gulf of Lion and Balearic Sea, circulates southward following five preferential pathways depending on the WIW formation site location and the oceanic conditions. WIW joins the northeastern part of the Balearic Sea, or flows along the continental shelves until joining the Balearic Current (maximum of 0.33 Sv in early-April) or further south until the Ibiza Channel entrance. Two additional trajectories, contributing to water mass exchanges with the southern part of the Western Mediterranean Sea, bring the WIW through the Ibiza and Mallorca Channels (maxima of 0.26 Sv in late-March and 0.1 Sv in early-April, respectively). The circulation of WIW over the NWMED at 50-200 m depth, its mixing and spreading over the Western Mediterranean Sea (reaching the south of the Balearic Islands, the Algero-Provencal basin, the Ligurian and the Alboran Seas) suggest that the WIW may have an impact on the ocean circulation by eddy blocking effect, exchange of water masses between north and south subbasins of Western Mediterranean Sea through the Ibiza Channel or modification of the ocean stratification.

Chlorination of bromide-containing waters: Enhanced bromate formation in the presence ofsynthetic metal oxides and deposits formed indrinking water distribution systems

KAUST Repository

Liu, Chao; von Gunten, Urs; Croue, Jean-Philippe

2013-01-01

Bromate formation from the reaction between chlorine and bromide in homogeneous solution is a slow process. The present study investigated metal oxides enhanced bromate formation during chlorination of bromide-containing waters. Selected metal oxides enhanced the decay of hypobromous acid (HOBr), a requisite intermediate during the oxidation of bromide to bromate, via (i) disproportionation to bromate in the presence of nickel oxide (NiO) and cupric oxide (CuO), (ii) oxidation of a metal to a higher valence state in the presence of cuprous oxide (Cu2O) and (iii) oxygen formation by NiO and CuO. Goethite (α-FeOOH) did not enhance either of these pathways. Non-charged species of metal oxides seem to be responsible for the catalytic disproportionation which shows its highest rate in the pH range near the pKa of HOBr. Due to the ability to catalyze HOBr disproportionation, bromate was formed during chlorination of bromide-containing waters in the presence of CuO and NiO, whereas no bromate was detected in the presence of Cu2O and α-FeOOH for analogous conditions. The inhibition ability of coexisting anions on bromate formation at pH 8.6 follows the sequence of phosphate>>sulfate>bicarbonate/carbonate. A black deposit in a water pipe harvested from a drinking water distribution system exerted significant residual oxidant decay and bromate formation during chlorination of bromide-containing waters. Energy dispersive spectroscopy (EDS) analyses showed that the black deposit contained copper (14%, atomic percentage) and nickel (1.8%, atomic percentage). Cupric oxide was further confirmed by X-ray diffraction (XRD). These results indicate that bromate formation may be of concern during chlorination of bromide-containing waters in distribution systems containing CuO and/or NiO. © 2013 Elsevier Ltd.

Chlorination of bromide-containing waters: Enhanced bromate formation in the presence ofsynthetic metal oxides and deposits formed indrinking water distribution systems

KAUST Repository

Liu, Chao

2013-09-01

Bromate formation from the reaction between chlorine and bromide in homogeneous solution is a slow process. The present study investigated metal oxides enhanced bromate formation during chlorination of bromide-containing waters. Selected metal oxides enhanced the decay of hypobromous acid (HOBr), a requisite intermediate during the oxidation of bromide to bromate, via (i) disproportionation to bromate in the presence of nickel oxide (NiO) and cupric oxide (CuO), (ii) oxidation of a metal to a higher valence state in the presence of cuprous oxide (Cu2O) and (iii) oxygen formation by NiO and CuO. Goethite (α-FeOOH) did not enhance either of these pathways. Non-charged species of metal oxides seem to be responsible for the catalytic disproportionation which shows its highest rate in the pH range near the pKa of HOBr. Due to the ability to catalyze HOBr disproportionation, bromate was formed during chlorination of bromide-containing waters in the presence of CuO and NiO, whereas no bromate was detected in the presence of Cu2O and α-FeOOH for analogous conditions. The inhibition ability of coexisting anions on bromate formation at pH 8.6 follows the sequence of phosphate>>sulfate>bicarbonate/carbonate. A black deposit in a water pipe harvested from a drinking water distribution system exerted significant residual oxidant decay and bromate formation during chlorination of bromide-containing waters. Energy dispersive spectroscopy (EDS) analyses showed that the black deposit contained copper (14%, atomic percentage) and nickel (1.8%, atomic percentage). Cupric oxide was further confirmed by X-ray diffraction (XRD). These results indicate that bromate formation may be of concern during chlorination of bromide-containing waters in distribution systems containing CuO and/or NiO. © 2013 Elsevier Ltd.

Reversible formation of high-valent-iron-oxo-porphyrin intermediate in heme-based catalysis: revisiting the kinetic model for horseradish peroxidase.

NARCIS (Netherlands)

Haandel, van M.J.H.; Primus, J.L.; Teunis, C.; Boersma, M.G.; Osman, A.M.; Veeger, C.; Rietjens, I.M.C.M.

1998-01-01

Many heme-containing biocatalysts exert their catalytic action through the initial formation of so-called high-valent-iron-oxo porphyrin intermediates. For horseradish peroxidase the initial intermediate formed has been identified as a high-valent-iron-oxo porphyrin π-radical cation, called compound

Water activity reduction of intermediate moisture yellowstrip trevally (Selaroides leptolepis

Directory of Open Access Journals (Sweden)

Phomajun, P.

2005-05-01

Full Text Available Water activity reduction of intermediate moisture yellowstrip trevally was studied. The optimal time (8, 12, 16, 20 hrs. for curing marinade was investigated. The effects of different humectants (glycerol, sorbitol, lactitol, glucose syrup at 50% w/w of curing ingredients were compared. Results showed that moisture content and water activity of cured yellowstrip trevally decreased as curing time increased (p0.05. However, the hardness of intermediate moisture Yellowstrip trevally, determined by texture analyzer, decreased. Hardness, shear force, L a b value of sample added with various humectants were lower than those of the control (p0.05. The glycerol-added samples had the highest overall acceptability score and were higher than control, whereas the glucose syrup-added samples had the lowest score. Moisture content of the samples with the addition of various humectants was higher than that of the control (18.28 %. The samples added with glycerol retained the highest moisture (24.94%. The adsorption isotherm studies showed that the equilibrium moisture of sample added with glycerol was higher than that added with lactitol.

Chlorination of bromide-containing waters: enhanced bromate formation in the presence of synthetic metal oxides and deposits formed in drinking water distribution systems.

Science.gov (United States)

Liu, Chao; von Gunten, Urs; Croué, Jean-Philippe

2013-09-15

Bromate formation from the reaction between chlorine and bromide in homogeneous solution is a slow process. The present study investigated metal oxides enhanced bromate formation during chlorination of bromide-containing waters. Selected metal oxides enhanced the decay of hypobromous acid (HOBr), a requisite intermediate during the oxidation of bromide to bromate, via (i) disproportionation to bromate in the presence of nickel oxide (NiO) and cupric oxide (CuO), (ii) oxidation of a metal to a higher valence state in the presence of cuprous oxide (Cu2O) and (iii) oxygen formation by NiO and CuO. Goethite (α-FeOOH) did not enhance either of these pathways. Non-charged species of metal oxides seem to be responsible for the catalytic disproportionation which shows its highest rate in the pH range near the pKa of HOBr. Due to the ability to catalyze HOBr disproportionation, bromate was formed during chlorination of bromide-containing waters in the presence of CuO and NiO, whereas no bromate was detected in the presence of Cu2O and α-FeOOH for analogous conditions. The inhibition ability of coexisting anions on bromate formation at pH 8.6 follows the sequence of phosphate > sulfate > bicarbonate/carbonate. A black deposit in a water pipe harvested from a drinking water distribution system exerted significant residual oxidant decay and bromate formation during chlorination of bromide-containing waters. Energy dispersive spectroscopy (EDS) analyses showed that the black deposit contained copper (14%, atomic percentage) and nickel (1.8%, atomic percentage). Cupric oxide was further confirmed by X-ray diffraction (XRD). These results indicate that bromate formation may be of concern during chlorination of bromide-containing waters in distribution systems containing CuO and/or NiO. Copyright © 2013 Elsevier Ltd. All rights reserved.

The lower body muscle activation of intermediate to experienced kayakers when navigating white water.

Science.gov (United States)

Murtagh, Misha; Brooks, Darrell; Sinclair, Jonathan; Atkins, Stephen

2016-11-01

In white-water kayaking, the legs play a vital part in turning, stabilising and bracing actions. To date, there has been no reported information on neuromuscular activation of the legs in an authentic white-water environment. The aim of the current study was to identify lower body muscle activation, using 'in-boat' electromyography (EMG), whilst navigating a white-water run. Ten experienced male kayakers (age 31.5 ± 12.5 yr, intermediate to advanced experience) completed three successful runs of an international standard white-water course (grade 3 rapids), targeting right and left sides of the course, in a zigzag formation. Surface EMG (sEMG) outputs were generated, bilaterally, for the rectus femoris (RF), vastus lateralis, biceps femoris and gastrocnemius, expressed as a percentage of a dynamic maximal voluntary contraction (dMVC). Only RF showed significantly higher activation than any muscle on the left side of the body, and only on the left side of the course (P = .004; ETA(2) = 0.56). Other results showed no significant difference between muscle activation in the right and left legs during each run, nor when assessed at either the right or left side of the course (P > .05). These findings indicate that contralateral symmetry in lower limb muscle activation is evident during white-water kayaking. This symmetry may provide a stable base to allow more asymmetrical upper body and trunk movements to be fully optimised. Lower body symmetry development should be considered useful in targeted training programmes for white-water kayakers.

Intermediate levels of hippocampal activity appear optimal for associative memory formation.

Directory of Open Access Journals (Sweden)

Xiao Liu

Full Text Available BACKGROUND: It is well established that hippocampal activity is positively related to effective associative memory formation. However, in biological systems often optimal levels of activity are contrasted by both sub- and supra-optimal levels. Sub-optimal levels of hippocampal activity are commonly attributed to unsuccessful memory formation, whereas the supra-optimal levels of hippocampal activity related to unsuccessful memory formation have been rarely studied. It is still unclear under what circumstances such supra-optimal levels of hippocampal activity occur. To clarify this issue, we aimed at creating a condition, in which supra-optimal hippocampal activity is associated with encoding failure. We assumed that such supra-optimal activity occurs when task-relevant information is embedded in task-irrelevant, distracting information, which can be considered as noise. METHODOLOGY/PRINCIPAL FINDINGS: In the present fMRI study, we probed neural correlates of associative memory formation in a full-factorial design with associative memory (subsequently remembered versus forgotten and noise (induced by high versus low distraction as factors. Results showed that encoding failure was associated with supra-optimal activity in the high-distraction condition and with sub-optimal activity in the low distraction condition. Thus, we revealed evidence for a bell-shape function relating hippocampal activity with associative encoding success. CONCLUSIONS/SIGNIFICANCE: Our findings indicate that intermediate levels of hippocampal activity are optimal while both too low and too high levels appear detrimental for associative memory formation. Supra-optimal levels of hippocampal activity seem to occur when task-irrelevant information is added to task-relevant signal. If such task-irrelevant noise is reduced adequately, hippocampal activity is lower and thus optimal for associative memory formation.

Surface-Bound Intermediates in Low-Temperature Methanol Synthesis on Copper. Participants and Spectators

Energy Technology Data Exchange (ETDEWEB)

Yang, Yong; Mei, Donghai; Peden, Charles HF; Campbell, Charles T.; Mims, Charles A.

2015-11-03

The reactivity of surface adsorbed species present on copper catalysts during methanol synthesis at low temperatures was studied by simultaneous infrared spectroscopy (IR) and mass spectroscopy (MS) measurements during “titration” (transient surface reaction) experiments with isotopic tracing. The results show that adsorbed formate is a major bystander species present on the surface under steady-state methanol synthesis reaction conditions, but it cannot be converted to methanol by reaction with pure H₂, nor with H₂ plus added water. Formate-containing surface adlayers for these experiments were produced during steady state catalysis in (a) H₂:CO₂ (with substantial formate coverage) and (b) moist H₂:CO (with no IR visible formate species). Both these reaction conditions produce methanol at steady state with relatively high rates. Adlayers containing formate were also produced by (c) formic acid adsorption. Various "titration" gases were used to probe these adlayers at modest temperatures (T = 410-450K) and 6 bar total pressure. Methanol gas (up to ~1% monolayer equivalent) was produced in "titration" from the H₂:CO₂ catalytic adlayers by H₂ plus water, but not by dry hydrogen. The decay in the formate IR features accelerated in the presence of added water vapor. The H₂:CO:H₂O catalytic adlayer produced similar methanol titration yields in H₂ plus water but showed no surface formate features in IR (less than 0.2% monolayer coverage). Finally, formate from formic acid chemisorption produced no methanol under any titration conditions. Even under (H₂:CO₂) catalytic reaction conditions, isotope tracing showed that pre-adsorbed formate from formic acid did not contribute to the methanol produced. Although non-formate intermediates exist during low temperature methanol synthesis on copper which can be converted to methanol gas

Chemical evolution of formation waters in the Palm Valley gas field, Northern Territory

International Nuclear Information System (INIS)

Andrew, A.S.; Giblin, A.M.

2000-01-01

The chemical composition and evolution of formation waters associated with gas production in the Palm Valley field, Northern Territory, has important implications for reservoir management, saline water disposal, and gas reserve calculations. Historically, the occurrence of saline formation water in gas fields has been the subject of considerable debate. A better understanding of the origin, chemical evolution and movement of the formation water at Palm Valley has important implications for future reservoir management, disposal of highly saline water and accurate gas reserves estimation. Major and trace element abundance data suggest that a significant component of the highly saline water from Palm Valley has characteristics that may have been derived from a modified evaporated seawater source such as an evaporite horizon. The most dilute waters probably represent condensate and the variation in the chemistry of the intermediate waters suggests they were derived from a mixture of the condensate with the highly saline brine. The chemical and isotopic results raise several interrelated questions; the ultimate source of the high salinity and the distribution of apparently mixed compositions. In this context several key observation are highlighted. Strontium concentrations are extremely high in the brines; although broadly similar in their chemistry, the saline fluids are neither homogeneous nor well mixed; the 87 Sr/ 86 Sr ratios in the brines are higher than the signatures preserved in the evaporitic Bitter Springs Formation, and all other conceivably marine-related evaporites (Strauss, 1993); the 87 Sr/ 86 Sr ratios in the brines are lower than those measured from groundmass carbonates in the host rocks, and that the 87 Sr/ 86 Sr ratios of the brines are similar, but still somewhat higher than those measured in vein carbonates from the reservoir. It is concluded that the high salinity brine entered the reservoir during the Devonian uplift and was subsequently

Secondary organic aerosol formation from biomass burning intermediates: phenol and methoxyphenols

Directory of Open Access Journals (Sweden)

L. D. Yee

2013-08-01

Full Text Available The formation of secondary organic aerosol from oxidation of phenol, guaiacol (2-methoxyphenol, and syringol (2,6-dimethoxyphenol, major components of biomass burning, is described. Photooxidation experiments were conducted in the Caltech laboratory chambers under low-NOx (2O2 as the OH source. Secondary organic aerosol (SOA yields (ratio of mass of SOA formed to mass of primary organic reacted greater than 25% are observed. Aerosol growth is rapid and linear with the primary organic conversion, consistent with the formation of essentially non-volatile products. Gas- and aerosol-phase oxidation products from the guaiacol system provide insight into the chemical mechanisms responsible for SOA formation. Syringol SOA yields are lower than those of phenol and guaiacol, likely due to novel methoxy group chemistry that leads to early fragmentation in the gas-phase photooxidation. Atomic oxygen to carbon (O : C ratios calculated from high-resolution-time-of-flight Aerodyne Aerosol Mass Spectrometer (HR-ToF-AMS measurements of the SOA in all three systems are ~ 0.9, which represent among the highest such ratios achieved in laboratory chamber experiments and are similar to that of aged atmospheric organic aerosol. The global contribution of SOA from intermediate volatility and semivolatile organic compounds has been shown to be substantial (Pye and Seinfeld, 2010. An approach to representing SOA formation from biomass burning emissions in atmospheric models could involve one or more surrogate species for which aerosol formation under well-controlled conditions has been quantified. The present work provides data for such an approach.

Biofilm formation in a hot water system

DEFF Research Database (Denmark)

Bagh, L.K.; Albrechtsen, Hans-Jørgen; Arvin, Erik

2002-01-01

The biofilm formation rate was measured in situ in a hot water system in an apartment building by specially designed sampling equipment, and the net growth of the suspended bacteria was measured by incubation of water samples with the indigeneous bacteria. The biofilm formation rate reached......, in the sludge, or in the water from the distribution system was negligible. This indicated that bacterial growth took place on the inner surfaces in the hot water system and biofilm formation and detachment of bacteria could account for most of the suspended bacteria actually measured in hot water. Therefore...

Investigating the Interannual Variability of the Circulation and Water Mass Formation in the Red Sea

Science.gov (United States)

Sofianos, S. S.; Papadopoulos, V. P.; Denaxa, D.; Abualnaja, Y.

2014-12-01

The interannual variability of the circulation and water mass formation in the Red Sea is investigated with the use of a numerical model and the combination of satellite and in-situ observations. The response of Red Sea to the large-scale variability of atmospheric forcing is studied through a 30-years simulation experiment, using MICOM model. The modeling results demonstrate significant trends and variability that are mainly located in the central and northern parts of the basin. On the other hand, the exchange pattern between the Red Sea and the Indian Ocean at the strait of Bab el Mandeb presents very weak interannual variability. The results verify the regularity of the water mass formation processes in the northern Red Sea but also show significant variability of the circulation and thermohaline conditions in the areas of formation. Enhanced water mass formation conditions are observed during specific years of the simulation (approximately five years apart). Analysis of recent warm and cold events in the northernmost part of the basin, based on a combination of atmospheric reanalysis results and oceanic satellite and in-situ observations, shows the importance of the cyclonic gyre that is prevailing in this part of the basin. This gyre can effectively influence the sea surface temperature (SST) and intensify or mitigate the winter effect of the atmospheric forcing. Upwelling induced by persistent periods of the gyre functioning drops the SST over the northernmost part of the Red Sea and can produce colder than normal winter SST even without extreme atmospheric forcing. These mechanisms are crucial for the formation of intermediate and deep water masses in the Red Sea and the strength of the subsequent thermohaline cells.

On the Effect of Online Formative Assessment on Iranian Lower Intermediate EFL Learners Reading Comprehension

Directory of Open Access Journals (Sweden)

Farideh Peyghambarian

2015-03-01

Full Text Available Online Formative Assessment (OFA improves EFL students’ reading comprehension enabling them to have a better performance in reading comprehension tests. To lend support to the above mentioned claim, a quasi-experimental study was conducted in Mashhad, Iran. 48 female lower intermediate EFL students took part in this study. Participants were assigned to control and treatment groups.  Participants in both groups received a formative assessment program lasting for 10 sessions. Formative assessment in treatment group was conducted by the site itself, and participants in control group were assessed by the teacher. It was found that participants in treatment group significantly outperformed those in control group. This finding indicated OFA as an effective learning tool in EFL reading comprehension classrooms.

The Role of Hydroxylamine as a Nitrification Intermediate in N-nitrosamine Formation

Science.gov (United States)

The formation of N-nitrosamines, and in particular N-nitrosodimethylamine (NDMA), in drinking water systems that use chloramines is a concern because of their potential carcinogenicity and occurrences in finished waters at toxicologically relevant levels. The widely accepted mech...

Collaborative Project. Mode and Intermediate Waters in Earth System Models

Energy Technology Data Exchange (ETDEWEB)

Sarmiento, Jorge L. [Princeton Univ., NJ (United States); Dufour, Carolina [Princeton Univ., NJ (United States); Rodgers, Keith B. [Princeton Univ., NJ (United States)

2015-12-16

The focus of this grant was on diagnosing the physical mechanisms controlling upper ocean water mass formation and carbon distribution in Earth System Models (ESMs), with the goal of improving the physics that controls their formation.

Slow and fast pyrolysis of Douglas-fir lignin: Importance of liquid-intermediate formation on the distribution of products

NARCIS (Netherlands)

Zhou, Shuai; Pecha, Brennan; van Kuppevelt, Michiel; McDonald, Armando G.; Garcia-Perez, Manuel

2014-01-01

The formation of liquid intermediates and the distribution of products were studied under slow and fast pyrolysis conditions. Results indicate that monomers are formed from lignin oligomeric products during secondary reactions, rather than directly from the native lignin. Lignin from Douglas-fir

Critical masses of bare homogeneous spherical UO2-water mixtures at intermediate enrichments

International Nuclear Information System (INIS)

Rendon, G.L.; Stratton, W.

1999-01-01

Critical masses of bare homogeneous spherical UO 2 -water mixtures at various intermediate fissile enrichments determined by multigroup, transport theory is presented. This work was performed to provide support for particular issues encountered by the nuclear industry when operating in the intermediate enrichment regime, namely, the validation of codes used to set criticality safety limits. Validation is normally performed with a comparison of computational results and applicable experiments. However, this may be difficult in some cases because of the lack of sufficient applicable experiments in the intermediate enrichment range. If a large extension of the area of applicability from an experiment to the desired application exists, then an alternative means for validation must be employed. Ideal interpretations of standard ANSI/ANS 8.1 Section 4.3 (1983) implies that perhaps an independent code and data system may be employed for validation purposes

Development of Non-Platinum Catalysts for Intermediate Temperature Water Electrolysis

DEFF Research Database (Denmark)

Nikiforov, Aleksey Valerievich; Petrushina, Irina Michailovna; Bjerrum, Niels J.

2014-01-01

Water electrolysis is recognized as an efficient energy storage (in the form of hydrogen) supplement in renewable energy production. However, industrial alkaline water electrolyzers are rather ineffective and space requiring for a commercial use in connection with energy storage. The most effective...... modern water electrolyzers are based on polymeric proton-conducting membrane electrolytes (PEM), e.g. Nafion®, a perfluorocarbon-sulfonic acid polymer. These electrolyzers work at temperatures up to around 80 °C, and, in extreme cases, up to 130-140 °C. The most developed PEM electrolyzers...... as electrolytes for the intermediate temperature applications, such as CsHSO4, KHSO45. The most successful systems have been developed with CsH2PO4 (solid acid fuel cells (SAFCs) and Sn0.9In0.1P2O7 electrolytes6,7. While developing materials for the promising medium temperature electrolysis systems...

Increased Ice-age Influence of Antarctic Intermediate Water.

Science.gov (United States)

Muratli, J.; McManus, J.; Mix, A.; Chase, Z.

2008-12-01

A depth transect of three ODP sites collected along the central Chile Margin constrain Antarctic Intermediate Water (AAIW) distributions and regional export production over the last 30 ka. Reduced Re and Cd, and increased Mn are proxies for higher bottom water oxygenation; 230Th-normalized burial of opal is a proxy for productivity. Mn/Al is high during the glacial interval at all three sites, suggesting high oxygenation and the retreat of the oxygen minimum zone during this period. At Site 1233, within the core of modern AAIW, Re and Cd are unchanged from detrital values throughout the last 30 ky, implying continuously oxic conditions. In contrast, at the northern sites 1234 and 1235, which reside below and above AAIW respectively, Re and Cd rise rapidly from low glacial values at ~15ka, signifying lower oxygen concentrations at the sea floor during Holocene time relative to ice-age conditions. Local productivity, recorded in Th-normalized opal burial, is highest during the glacial interval at both sites 1233 and 1234, and varies independently from the redox proxies. We conclude that local productivity does not drive bottom water oxygenation here, and that ventilation of the shallow subsurface southeast Pacific increased during the last ice age, with an expanded depth range of AAIW relative to the present.

Effect of ultrasonic waves on the water turbidity during the oxidation of phenol. Formation of (hydro)peroxo complexes.

Science.gov (United States)

Villota, Natalia; Lomas, Jose M; Camarero, Luis M

2017-11-01

Analysis of the kinetics of aqueous phenol oxidation by a sono-Fenton process reveals that the via involving ortho-substituted intermediates prevails: catechol (25.0%), hydroquinone (7.7%) and resorcinol (0.6%). During the oxidation, water rapidly acquires color that reaches its maximum intensity at the maximum concentration of p-benzoquinone. Turbidity formation occurs at a slower rate. Oxidant dosage determines the nature of the intermediates, being trihydroxylated benzenes (pyrogallol, hydroxyhydroquinone) and muconic acid the main precursors causing turbidity. It is found that the concentration of iron species and ultrasonic waves affects the intensity of the turbidity. The pathway of (hydro)peroxo-iron(II) complexes formation is proposed. Operating with 20.0-27.8mgFe 2+ /kW rates leads to formation of (hydro)peroxo-iron(II) complexes, which induce high turbidity levels. These species would dissociate into ZZ-muconic acid and ferrous ions. Applying relationships around 13.9mgFe 2+ /kW, the formation of (hydro)peroxo-iron(III) complexes would occur, which could react with carboxylic acids (2,5-dioxo-3-hexenedioic acid). That reaction induces turbidity slower. This is due to the organic substrate reacting with two molecules of the (hydro)peroxo complex. Therefore, it is necessary to accelerate the iron regeneration, intensifying the ultrasonic irradiation. Afterwards, this complex would dissociate into maleic acid and ferric ions. Copyright © 2017 Elsevier B.V. All rights reserved.

N-nitrosodimethylamine (NDMA) formation potential of amine-based water treatment polymers: Effects of in situ chloramination, breakpoint chlorination, and pre-oxidation.

Science.gov (United States)

Park, Sang Hyuck; Padhye, Lokesh P; Wang, Pei; Cho, Min; Kim, Jae-Hong; Huang, Ching-Hua

2015-01-23

Recent studies show that cationic amine-based water treatment polymers may be important precursors that contribute to formation of the probable human carcinogen N-nitrosodimethylamine (NDMA) during water treatment and disinfection. To better understand how water treatment parameters affect NDMA formation from the polymers, the effects of in situ chloramination, breakpoint chlorination, and pre-oxidation on the NDMA formation from the polymers were investigated. NDMA formation potential (NDMA-FP) as well as dimethylamine (DMA) residual concentration were measured from poly(epichlorohydrin dimethylamine) (polyamine) and poly(diallyldimethylammonium chloride) (polyDADMAC) solutions upon reactions with oxidants including free chlorine, chlorine dioxide, ozone, and monochloramine under different treatment conditions. The results supported that dichloramine (NHCl2) formation was the critical factor affecting NDMA formation from the polymers during in situ chloramination. The highest NDMA formation from the polymers occurred near the breakpoint of chlorination. Polymer chain breakdown and transformation of the released DMA and other intermediates were important factors affecting NDMA formation from the polymers in pre-oxidation followed by post-chloramination. Pre-oxidation generally reduced NDMA-FP of the polymers; however, the treatments involving pre-ozonation increased polyDADMAC's NDMA-FP and DMA release. The strategies for reducing NDMA formation from the polymers may include the avoidance of the conditions favorable to NHCl2 formation and the avoidance of polymer exposure to strong oxidants such as ozone. Copyright © 2014 Elsevier B.V. All rights reserved.

Southern Ocean Surface and Intermediate Water Temperature from Alkenones and Mg/Ca of Infaunal Foraminifera for the last 1.5 Ma

Science.gov (United States)

Elmore, Aurora; McClymont, Erin; Elderfield, Harry; Kender, Sev

2014-05-01

The reconstruction of past surface (SST), intermediate, and deep-water temperatures is critical to our understanding of feedbacks within the ocean-climate system. Intermediate water temperature (IWT) reconstruction is particularly important since intermediate waters, including Antarctic Intermediate Water (AAIW), are proposed to be an important driver in high-low latitude teleconnections, despite limited intermediate-depth records through the Pliocene and Pleistocene. Paleotemperature proxies have caveats, including the 'Carbonate Ion Effect' on the Magnesium to Calcium ratio (Mg/Ca) of benthic foraminifera. However, recent studies demonstrated that the infaunal species, Uvigerina peregrina, co-precipitates Mg independent of secondary effects, affording the use of U.peregrina Mg/Ca as a paleotemperature proxy (Elderfield et al., 2010). We present the first 1.5 Ma record of IWT from Mg/CaU.peregrina coupled with an alkenone- derived UK37' SST record from a sediment core in the Southwest Pacific (DSDP site 593; 1068m water depth), in the core of modern AAIW. Our new data reconstruct interglacial IWTs at ~7°C before and after the Mid-Pleistocene Transition (MPT), whereas values of ~5°C occur in the later Pleistocene. Glacial IWT remained fairly constant (~2°C) throughout the last 1 Ma. These results are in apparent disagreement with the typical idea that glacial-interglacial temperature fluctuations were smaller in the '41-kyr world' before the MPT, than during the '100-kyr world', after the MPT. At proximal ODP site 1123 (3290m water depth; Elderfield et al., 2012), interglacial deepwater temperatures increase by ~1°C after the MPT, with relatively constant glacial deepwater temperatures (~-2°C) over the last 1 Ma. New results from DSDP 593 therefore imply that the mechanisms that drive intermediate and deep water temperatures varied, suggesting that at least one of these watermasses has properties driven by something other than Northern Hemisphere glaciation

Characterization of biodegradation intermediates of nonionic surfactants by MALDI-MS. 2. Oxidative biodegradation profiles of uniform octylphenol polyethoxylate in 18O-labeled water.

Science.gov (United States)

Sato, Hiroaki; Shibata, Atsushi; Wang, Yang; Yoshikawa, Hiromichi; Tamura, Hiroto

2003-01-01

This paper reports the characterization of the biodegradation intermediates of octylphenol octaethoxylate (OP(8)EO) by means of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The biodegradation test study was carried out in a pure culture (Pseudomonas putida S-5) under aerobic conditions using OP(8)EO as the sole carbon source and (18)O-labeled water as an incubation medium. In the MALDI-MS spectra of biodegraded samples, a series of OP(n)EO molecules with n = 2-8 EO units and their corresponding carboxylic acid products (OP(n)EC) were observed. The use of purified OP(8)EO enabled one to distinguish the shortened OPEO molecules as biodegradation intermediates. Furthermore, the formation of OP(8)EC (the oxidized product of OP(8)EO) supported the notion that terminal oxidation is a step in the biodegradation process. When biodegradation study was carried out in (18)O-labeled water, incorporation of (18)O atoms into the carboxyl group was observed for OPEC, while no incorporation was observed for the shortened OPEO products. These results could provide some rationale to the biodegradation mechanism of alkylphenol polyethoxylates.

The Role of Hydroxylamine as a Nitrification Intermediate in N-Nitrosamine Formation- Indianapolis

Science.gov (United States)

The formation of N-nitrosamines, and in particular N-nitrosodimethylamine (NDMA), in drinking water systems that use chloramines is a concern because of their potential carcinogenicity and occurrences in finished waters at toxicologically relevant levels. The widely accepted mech...

Extant or Absent: Formation Water in New York State Drinking Water Wells

Science.gov (United States)

Christian, K.; Lautz, L. K.

2013-12-01

The current moratorium on hydraulic fracturing in New York State (NYS) provides an opportunity to collect baseline shallow groundwater quality data pre-hydraulic fracturing, which is essential for determining the natural variability of groundwater chemistry and to evaluate future claims of impaired groundwater quality if hydraulic fracturing occurs in the State. Concerns regarding the future environmental impact of shale gas extraction in NYS include potential shallow groundwater contamination due to migration of methane or formation water from shale gas extraction sites. Treatment, storage and disposal of saline flowback fluids after gas extraction could also be a source of water contamination. In this study, we combine southern NYS shallow groundwater chemistry data from Project Shale-Water Interaction Forensic Tools (SWIFT, n=60), the National Uranium Resource Evaluation program (NURE, n=684), and the USGS 305(b) Ambient Groundwater Quality Monitoring program (USGS, n=89) to examine evidence of formation water mixing with groundwater using the methodology of Warner et al. (2012). Groundwater characterized as low salinity (20 mg/L Cl-). A plot of bromide versus chloride shows high salinity groundwater samples with Br/Cl ratios >0.0001 fall on the mixing line between low salinity groundwater and Appalachian Basin formation water. Based on the observed linear relationship between bromide and chloride, it appears there is up to 1% formation water mixing with shallow groundwater in the region. The presence of formation water in shallow groundwater would indicate the existence of natural migratory pathways between deep formation wells and shallow groundwater aquifers. A plot of sodium versus chloride also illustrates a linear trend for Type D waters (R^2= 0.776), but the relationship is weaker than that for bromide versus chloride (R^2= 0.924). Similar linear relationships are not observed between other ions and chloride, including Mg, Ca, and Sr. If high salinity

EXTENDED STAR FORMATION IN THE INTERMEDIATE-AGE LARGE MAGELLANIC CLOUD STAR CLUSTER NGC 2209

International Nuclear Information System (INIS)

Keller, Stefan C.; Mackey, A. Dougal; Da Costa, Gary S.

2012-01-01

We present observations of the 1 Gyr old star cluster NGC 2209 in the Large Magellanic Cloud made with the GMOS imager on the Gemini South Telescope. These observations show that the cluster exhibits a main-sequence turnoff that spans a broader range in luminosity than can be explained by a single-aged stellar population. This places NGC 2209 amongst a growing list of intermediate-age (1-3 Gyr) clusters that show evidence for extended or multiple epochs of star formation of between 50 and 460 Myr in extent. The extended main-sequence turnoff observed in NGC 2209 is a confirmation of the prediction in Keller et al. made on the basis of the cluster's large core radius. We propose that secondary star formation is a defining feature of the evolution of massive star clusters. Dissolution of lower mass clusters through evaporation results in only clusters that have experienced secondary star formation surviving for a Hubble time, thus providing a natural connection between the extended main-sequence turnoff phenomenon and the ubiquitous light-element abundance ranges seen in the ancient Galactic globular clusters.

Formation waters of the Norwegian Continental Shelf

Energy Technology Data Exchange (ETDEWEB)

McCartney, R. A.; Rein, E.

2006-03-15

New and previously published analyses of formation waters for the Norwegian Continental Shelf (NCS) have been evaluated and interpreted to determine the compositional distribution of formation waters in the region and factors controlling their compositions, and also to obtain information on subsurface fluid flow. Formation waters in the region are Na-Cl and Na-Ca-Cl-type waters that display a wide range of salinity (2500-212000 mg/kg Cl). Generally, the concentrations of most dissolved constituents are positively correlated with Cl so that their distribution in formation waters largely reflects the variations shown by salinity. Exceptions are SO4 which is generally low (less than 40 mg/l) regardless of Cl, and HCO3 and in-situ pH which are negatively correlated with Cl. The main factors determining the compositions of the formation waters are mixing of meteoric water (probably late-Jurassic to Eocene), ancient seawater and primary brine together with diagenetic reactions that have affected each of these components individually as well as mixtures of them. Evaluation of the distribution of salinity has helped us identify where vertical and/or lateral migration of brine from the evaporites has occurred. This has in turn provided us with information on the presence of leak-points and vertical mixing, although further investigation of the location of evaporites and basin palaeohydrogeology are required to determine whether regional lateral advection has occurred in the past. The results of this study may benefit oil exploration and production activities in the NCS including constraint of hydrocarbon migration models, economic evaluation of undrilled prospects, scale management and compartmentalisation studies. (Author)

The initial step of silicate versus aluminosilicate formation in zeolite synthesis: a reaction mechanism in water with a tetrapropylammonium template

KAUST Repository

Trinh, Thuat T.

2012-01-01

The initial step for silicate and aluminosilicate condensation is studied in water in the presence of a realistic tetrapropylammonium template under basic conditions. The model corresponds to the synthesis conditions of ZSM5. The free energy profile for the dimer formation ((OH) 3Si-O-Si-(OH) 2O - or [(OH) 3Al-O-Si-(OH) 3] -) is calculated with ab initio molecular dynamics and thermodynamic integration. The Si-O-Si dimer formation occurs in a two-step manner with an overall free energy barrier of 75 kJ mol -1. The first step is associated with the Si-O bond formation and results in an intermediate with a five-coordinated Si, and the second one concerns the removal of the water molecule. The template is displaced away from the Si centres upon dimer formation, and a shell of water molecules is inserted between the silicate and the template. The main effect of the template is to slow down the backward hydrolysis reaction with respect to the condensation one. The Al-O-Si dimer formation first requires the formation of a metastable precursor state by proton transfer from Si(OH) 4 to Al(OH) 4 - mediated by a solvent molecule. It then proceeds through a single step with an overall barrier of 70 kJ mol -1. The model with water molecules explicitly included is then compared to a simple calculation using an implicit continuum model for the solvent. The results underline the importance of an explicit and dynamical treatment of the water solvent, which plays a key role in assisting the reaction. © the Owner Societies 2012.

Formation and decay of the intermediate quasistationary ion N-2 during charge exchange between fast H- ions and nitrogen molecules

International Nuclear Information System (INIS)

Kazanskii, A.K.

1984-01-01

The detachment of the electron from the H - ion during a collision with the nitrogen molecule at 1--6 keV occurs as a result of charge transfer to an unstable intermediate state of the molecular ion N - 2 and the subsequent decay of the ion. The formation process is described in the impulse approximation, and the motion of nuclei in the ion is treated quasiclassically. Expressions are obtained for the spectrum of emitted electrons and for the energy-loss spectrum of heavy particles. These expressions relate the spectra to the cross sections for the vibrational excitation of N 2 by electron impact. A convenient expression for the amplitude for the formation of the intermediate state is obtained in the ''boomerang'' model, and it is shown that one of the parameters, considered to be adjustable in traditional theory, can be calculated

Formation and fates of nitrosamines and their formation potentials from a surface water source to drinking water treatment plants in Southern Taiwan.

Science.gov (United States)

Chen, Wei-Hsiang; Wang, Chung-Ya; Huang, Tsung-Hsien

2016-10-01

Nitrosamines are toxic and emerging disinfection byproducts. In this study, three drinking water treatment plants (DWTPs) in southern Taiwan treating the same source water in Gaoping River with comparable technologies were selected. The objective was to evaluate the formation and fates of six nitrosamines and their formation potentials (FPs) from a surface water source to drinking water. Albeit decreased further downstream in the river, four nitrosamine-FPs were observed in the source water due to anthropogenic pollution in the upstream areas. In the DWTPs, nitrosamines were formed and NDMA was the main species. While high organic carbon concentrations indicated elevated nitrosamine-FPs in the source water, NDMA formation in the DWTPs was more positively associated with reductions of water parameters that quantify organic matters with double bonded ring structures. Although precursor removal via pre-oxidation is a viable approach to limit nitrosamine formation during post-disinfection, this study clearly indicates that a great portion of NDMA in treated water has been formed in the 1st oxidation step of drinking water treatment. The pre-oxidation simulations in the lab demonstrated the impact of pre-chlorination on nitrosamine formation. Given the limited removal in conventional treatment processes, avoiding nitrosamine-FPs in sources and/or nitrosamine formation during pre-oxidation become important issues to control the threats of nitrosamines in drinking water. Under current circumstance in which pre-oxidation is widely used to optimize the treatment effectiveness in many DWTPs, its adverse effect by forming nitrosamines needs to be carefully minimized and using technologies other than pre-chlorination (e.g., pre-ozonation) may be considered. Copyright © 2016 Elsevier Ltd. All rights reserved.

A theoretical model investigation of peptide bond formation involving two water molecules in ribosome supports the two-step and eight membered ring mechanism

International Nuclear Information System (INIS)

Wang, Qiang; Gao, Jun; Zhang, Dongju; Liu, Chengbu

2015-01-01

Highlights: • We theoretical studied peptide bond formation reaction mechanism with two water molecules. • The first water molecule can decrease the reaction barriers by forming hydrogen bonds. • The water molecule mediated three-proton transfer mechanism is the favorable mechanism. • Our calculation supports the two-step and eight membered ring mechanism. - Abstract: The ribosome is the macromolecular machine that catalyzes protein synthesis. The kinetic isotope effect analysis reported by Strobel group supports the two-step mechanism. However, the destination of the proton originating from the nucleophilic amine is uncertain. A computational simulation of different mechanisms including water molecules is carried out using the same reaction model and theoretical level. Formation the tetrahedral intermediate with proton transfer from nucleophilic nitrogen, is the rate-limiting step when two water molecules participate in peptide bond formation. The first water molecule forming hydrogen bonds with O9′ and H15′ in the A site can decrease the reaction barriers. Combined with results of the solvent isotope effects analysis, we conclude that the three-proton transfer mechanism in which water molecule mediate the proton shuttle between amino and carbon oxygen in rate-limiting step is the favorable mechanism. Our results will shield light on a better understand the reaction mechanism of ribosome

Water formation via HCl oxidation on Cu(1 0 0)

Energy Technology Data Exchange (ETDEWEB)

Suleiman, Ibrahim A., E-mail: isuleman@taibahu.edu.sa [College of Engineering, Taibah University, Yanbu 41911 (Saudi Arabia); Radny, Marian W. [School of Mathematical and Physical Sciences, The University of Newcastle, Callaghan, NSW 2308 (Australia); Institute of Physics, Poznan University of Technology, 62-956 Poznan (Poland); Gladys, Michael J.; Smith, Phillip V. [School of Mathematical and Physical Sciences, The University of Newcastle, Callaghan, NSW 2308 (Australia); Mackie, John C. [School of Engineering, The University of Newcastle, Callaghan, NSW 2308 (Australia); School of Chemistry, The University of Sydney (Australia); Stockenhuber, Michael; Kennedy, Eric M. [School of Engineering, The University of Newcastle, Callaghan, NSW 2308 (Australia); Dlugogorski, Bogdan Z. [School of Engineering, The University of Newcastle, Callaghan, NSW 2308 (Australia); School of Engineering and Information Technology, Murdoch University, Perth (Australia)

2014-04-01

Graphical abstract: This work investigates water formation on the Cu(1 0 0) surface via HCl oxidation using density functional theory and periodic slabs. We show that there are two different pathways for water formation on the surface depending on the temperature and oxygen coverage. - Highlights: • Pre-adsorbed chlorine increases the stability of water on Cu(1 0 0). • Two different pathways describe water formation on Cu(1 0 0) via HCl oxidation. • The mechanism of H{sub 2}O formation depends on the temperature and oxygen coverage. - Abstract: Using density functional theory and periodic slabs, we have studied water formation via HCl oxidation on the Cu(1 0 0) surface. We show that while adsorbed chlorine increases the stability of water on the Cu(1 0 0) surface, water molecules dissociate immediately when located next to an oxygen atom. We also show that these competing interactions, when arising from HCl reacting with oxygen on Cu(1 0 0), lead to water formation according to two different pathways depending on the temperature and oxygen coverage.

Formation of 4-hydroxy-2,5-dimethyl-3[2H]-furanone by Zygosaccharomyces rouxii: identification of an intermediate.

Science.gov (United States)

Hauck, Tobias; Brühlmann, Fredi; Schwab, Wilfried

2003-07-01

The formation of the important flavor compound 4-hydroxy-2,5-dimethyl-3[2H]-furanone (HDMF; Furaneol) from D-fructose-1,6-bisphosphate by the yeast Zygosaccharomyces rouxii was studied with regard to the identification of intermediates present in the culture medium. Addition of o-phenylenediamine, a trapping reagent for alpha-dicarbonyls, to the culture medium and subsequent analysis by high-pressure liquid chromatography with diode array detection revealed the formation of three quinoxaline derivatives derived from D-fructose-1,6-bisphosphate under the applied growth conditions (30 degrees C; pH 4 to 5). Isolation and characterization of these compounds by tandem mass spectrometry and nuclear magnetic resonance spectroscopy led to the identification of phosphoric acid mono-(2,3,4-trihydroxy-4-quinoxaline-2-yl-butyl) ester (Q1), phosphoric acid mono-[2,3-dihydroxy-3-(3-methyl-quinoxaline-2-yl)-propyl] ester (Q2), and phosphoric acid mono-[2-hydroxy-3-(3-methyl-quinoxaline-2-yl)-propyl] ester (Q3). Q1 and Q2 were formed independently of Z. rouxii cells, whereas Q3 was detected only in incubation systems containing the yeast. Identification of Q2 demonstrated for the first time the chemical formation of 1-deoxy-2,3-hexodiulose-6-phosphate in the culture medium, a generally expected but never identified intermediate in the formation pathway of HDMF. Since HDMF was detected only in the presence of Z. rouxii cells, additional enzymatic steps were presumed. Incubation of periplasmic and cytosolic protein extracts obtained from yeast cells with D-fructose-1,6-bisphosphate led to the formation of HDMF, implying the presence of the required enzymes in both extracts.

Red Sea Intermediate Water at the Agulhas Current termination

Science.gov (United States)

Roman, R. E.; Lutjeharms, J. R. E.

2007-08-01

The inter-ocean exchange of water masses at the Agulhas Current termination comes about through the shedding of rings, and this process plays an important role in the global thermohaline circulation. Using several hydrographic sections collected during the ARC (Agulhas Retroflection Cruise), MARE (Mixing of Agulhas Rings Experiment) and WOCE (World Ocean Circulation Experiment), this investigation aims to establish the degree to which Red Sea Intermediate Water (RSIW) is involved in this exchange and at what level of purity. To this end a wide range of hydrographic parameters were used. Upstream from the Agulhas Current retroflection water with clear RSIW origin is shown to move downstream on both the landward and seaward sides of the Agulhas Current with the highest water sample purity or water-mass content exceeding 15%. The least mixed water was found close to the continental shelf. At the retroflection the RSIW purity shows considerable variability that ranges between 5% and 20%. This suggests that RSIW moves down the current in patches of considerably varying degrees of previous mixing. This pattern was also observed in a ring sampled during the ARC experiment. The MARE sections in turn indicate that at times RSIW may be entirely absent in the Agulhas Current. RSIW is therefore shown to travel down the current as discontinuous filaments, and this intermittency is reflected in its presence in Agulhas Rings. From the sections investigated it is therefore clear that any calculation of RSIW fluxes involved in inter-ocean exchange can only be done on the basis of event scales. RSIW not trapped in Agulhas Rings flows east with the Agulhas Return Current.

Formation of RNA phosphodiester bond by histidine-containing dipeptides

DEFF Research Database (Denmark)

Wieczorek, Rafal; Dörr, Mark; Chotera, Agata

2013-01-01

A new scenario for prebiotic formation of nucleic acid oligomers is presented. Peptide catalysis is applied to achieve condensation of activated RNA monomers into short RNA chains. As catalysts, L-dipeptides containing a histidine residue, primarily Ser-His, were used. Reactions were carried out...... in self-organised environment, a water-ice eutectic phase, with low concentrations of reactants. Incubation periods up to 30 days resulted in the formation of short oligomers of RNA. During the oligomerisation, an active intermediate (dipeptide-mononucleotide) is produced, which is the reactive species...... by a transamination mechanism. Because peptides are much more likely products of spontaneous condensation than nucleotide chains, their potential as catalysts for the formation of RNA is interesting from the origin-of-life perspective. Finally, the formation of the dipeptide-mononucleotide intermediate and its...

Dimerization interface of 3-hydroxyacyl-CoA dehydrogenase tunes the formation of its catalytic intermediate.

Directory of Open Access Journals (Sweden)

Yingzhi Xu

Full Text Available 3-Hydroxyacyl-CoA dehydrogenase (HAD, EC 1.1.1.35 is a homodimeric enzyme localized in the mitochondrial matrix, which catalyzes the third step in fatty acid β-oxidation. The crystal structures of human HAD and subsequent complexes with cofactor/substrate enabled better understanding of HAD catalytic mechanism. However, numerous human diseases were found related to mutations at HAD dimerization interface that is away from the catalytic pocket. The role of HAD dimerization in its catalytic activity needs to be elucidated. Here, we solved the crystal structure of Caenorhabditis elegans HAD (cHAD that is highly conserved to human HAD. Even though the cHAD mutants (R204A, Y209A and R204A/Y209A with attenuated interactions on the dimerization interface still maintain a dimerization form, their enzymatic activities significantly decrease compared to that of the wild type. Such reduced activities are in consistency with the reduced ratios of the catalytic intermediate formation. Further molecular dynamics simulations results reveal that the alteration of the dimerization interface will increase the fluctuation of a distal region (a.a. 60-80 that plays an important role in the substrate binding. The increased fluctuation decreases the stability of the catalytic intermediate formation, and therefore the enzymatic activity is attenuated. Our study reveals the molecular mechanism about the essential role of the HAD dimerization interface in its catalytic activity via allosteric effects.

Thermal decomposition of barium ferrate(VI): Mechanism and formation of FeIV intermediate and nanocrystalline Fe2O3 and ferrite

International Nuclear Information System (INIS)

Machala, Libor; Sharma, Virender K.; Kuzmann, Ernö; Homonnay, Zoltán; Filip, Jan; Kralchevska, Radina P.

2016-01-01

Simple high-valent iron-oxo species, ferrate(VI) (Fe VI O 4 2− , Fe(VI)) has applications in energy storage, organic synthesis, and water purification. Of the various salts of Fe(VI), barium ferrate(VI) (BaFeO 4 ) has also a great potential as a battery material. This paper presents the thermal decomposition of BaFeO 4 in static air and nitrogen atmosphere, monitored by combination of thermal analysis, Mössbauer spectroscopy, X-ray powder diffraction, and electron-microscopic techniques. The formation of Fe IV species in the form of BaFeO 3 was found to be the primary decomposition product of BaFeO 4 at temperature around 190 °C under both studied atmospheres. BaFeO 3 was unstable in air reacting with CO 2 to form barium carbonate and speromagnetic amorphous iron(III) oxide nanoparticles (<5 nm). Above 600 °C, a solid state reaction between BaCO 3 and Fe 2 O 3 occurred, leading to the formation of barium ferrite nanoparticles, BaFe 2 O 4 (20–100 nm). - Highlights: • We explained the mechanism of thermal decomposition of barium ferrate(VI). • We confirmed the formation of Fe(IV) intermediate phase during the decomposition. • The mechanism of the decomposition is influenced by a presence of carbon dioxide.

Nitrate formation during ozonation as a surrogate parameter for abatement of micropollutants and the N-nitrosodimethylamine (NDMA) formation potential.

Science.gov (United States)

Song, Yang; Breider, Florian; Ma, Jun; von Gunten, Urs

2017-10-01

In this study, nitrate formation from ammonium and/or dissolved organic nitrogen (DON) was investigated as a novel surrogate parameter to evaluate the abatement of micropollutants during ozonation of synthetic waters containing natural organic matter (NOM) isolates, a natural water and secondary wastewater effluents. Nitrate formation during ozonation was compared to the changes in UV absorbance at 254 nm (UVA 254 ) including the effect of pH. For low specific ozone doses UVA 254 was abated more efficiently than nitrate was formed. This is due to a relatively slow rate-limiting step for nitrate formation from the reaction between ozone and a proposed nitrogen-containing intermediate. This reaction cannot compete with the fast reactions between ozone and UV-absorbing moieties (e.g., activated aromatic compounds). To further test the kinetics of nitrate formation, two possible intermediates formed during ozonation of DON were tested. At pH 7, nitrate was formed during ozonation of acetone oxime and methyl nitroacetate with second-order rate constants of 256.7 ± 4.7 M -1  s -1 and 149.5 ± 5.8 M -1  s -1 , respectively. The abatement of the selected micropollutants (i.e., 17α-ethinylestradiol (EE2), carbamazepine (CBZ), bezafibrate (BZF), ibuprofen (IBU), and p-chlorobenzoic acid (pCBA)) was investigated for specific ozone doses ≤1.53 mgO 3 /mgDOC and its efficiency depended strongly on the reactivity of the selected compounds with ozone. The relative abatement of micropollutants (i.e., EE2 and CBZ) with high ozone reactivity showed linear relationships with nitrate formation. The abatement of micropollutants with intermediate-low ozone reactivity (BZF, IBU, and pCBA) followed one- and two-phase behaviors relative to nitrate formation during ozonation of water samples containing high and low concentrations of nitrate-forming DON, respectively. During ozonation of a wastewater sample, the N-nitrosodimethylamine formation potential (NDMA-FP) during

Stability and anti-glycation properties of intermediate moisture apple products fortified with green tea.

Science.gov (United States)

Lavelli, Vera; Corey, Mark; Kerr, William; Vantaggi, Claudia

2011-07-15

Intermediate moisture products made from blanched apple flesh and green tea extract (about 6mg of monomeric flavan 3-ols added per g of dry apple) or blanched apple flesh (control) were produced, and their quality attributes were investigated over storage for two months at water activity (a(w)) levels of 0.55 and 0.75, at 30°C. Products were evaluated for colour (L(∗), a(∗), and b(∗) Hunter's parameters), phytochemical contents (flavan 3-ols, chlorogenic acid, dihydrochalcones, ascorbic acid and total polyphenols), ferric reducing antioxidant potential, 2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl radical-scavenging activity and ability to inhibit formation of fructose-induced advanced glycation end-products. During storage of the fortified and unfortified intermediate moisture apples, water availability was sufficient to support various chemical reactions involving phytochemicals, which degraded at different rates: ascorbic acid>flavan 3-ols>dihydrochalcones and chlorogenic acid. Colour variations occurred at slightly slower rates after green tea addition. In the intermediate moisture apple, antioxidant and anti-glycoxidative properties decreased at similar rates (half-life was about 80d at a(w) of 0.75, 30°C). In the green tea-fortified intermediate moisture apple, the antioxidant activity decreased at a slow rate (half-life was 165d at a(w) of 0.75, 30°C) and the anti-glycoxidative properties did not change, indicating that flavan 3-ol degradation involved the formation of derivatives that retained the properties of their parent compounds. Since these properties are linked to oxidative- and advanced glycation end-product-related diseases, these results suggest that green tea fortification of intermediate moisture apple products could be a valuable means of product innovation, to address consumers' nutritional needs. Copyright © 2011 Elsevier Ltd. All rights reserved.

Roles of different initial Maillard intermediates and pathways in meat flavor formation for cysteine-xylose-glycine model reaction systems.

Science.gov (United States)

Hou, Li; Xie, Jianchun; Zhao, Jian; Zhao, Mengyao; Fan, Mengdie; Xiao, Qunfei; Liang, Jingjing; Chen, Feng

2017-10-01

To explore initial Maillard reaction pathways and mechanisms for maximal formation of meaty flavors in heated cysteine-xylose-glycine systems, model reactions with synthesized initial Maillard intermediates, Gly-Amadori, TTCA (2-threityl-thiazolidine-4-carboxylic acids) and Cys-Amadori, were investigated. Relative relativities were characterized by spectrophotometrically monitoring the development of colorless degradation intermediates and browning reaction products. Aroma compounds formed were determined by solid-phase microextraction combined with GC-MS and GC-olfactometry. Gly-Amadori showed the fastest reaction followed by Cys-Amadori then TTCA. Free glycine accelerated reaction of TTCA, whereas cysteine inhibited that of Gly-Amadori due to association forming relatively stable thiazolidines. Cys-Amadori/Gly had the highest reactivity in development of both meaty flavors and brown products. TTCA/Gly favored yielding meaty flavors, whereas Gly-Amadori/Cys favored generation of brown products. Conclusively, initial formation of TTCA and pathway involving TTCA with glycine were more applicable to efficiently produce processed-meat flavorings in a cysteine-xylose-glycine system. Copyright © 2017 Elsevier Ltd. All rights reserved.

No evidence for a deglacial intermediate water Δ14C anomaly in the SW Atlantic

Science.gov (United States)

Sortor, R. N.; Lund, D. C.

2010-12-01

Reconstructions of Δ14C from the eastern tropical Pacific show that severe depletions in 14C occurred at intermediate depths during the last deglaciation (Marchitto et al. 2007; Stott et al. 2009). Marchitto et al. (2007) suggested that old radiocarbon from an isolated abyssal reservoir was injected via the Southern Ocean, and that this anomaly was then carried by Antarctic Intermediate Water (AAIW) to the tropical Pacific. However, a core from the southeastern Pacific Ocean near Chile, which is in the direct path of modern-day AAIW, does not exhibit the excursion and therefore casts doubts upon the AAIW mechanism (De Pol-Holz et al. 2010). Here we evaluate whether or not a deglacial 14C anomaly similar to that in the eastern tropical Pacific occurred at intermediate depths in the South Atlantic. We reconstructed Δ14C using planktonic and benthic foraminifera from core KNR159-5-36GGC on the Brazil Margin (27○31’S and 46○28’W, 1268 m depth). In the modern ocean, the hydrography near this core site is heavily influenced by AAIW (Oppo & Horowitz, 2000). Benthic Δ14C values were determined using raw benthic 14C ages and calendar-calibrated planktonic ages. The deglacial benthic Δ14C trend at this site is similar to the atmospheric Δ14C trend, and is consistent with U/Th-dated corals from intermediate depths on the Brazil Margin (Mangini et al. 2010). The amplitude and timing of Δ14C changes in the foraminiferal and coral records are especially congruous during the Mystery Interval. We find no evidence in the southwestern Atlantic of a ~300‰ decrease in intermediate water Δ14C beginning at 18 kyr BP. Changes in reservoir age of ~1000 years are required to create a Baja-like Δ14C anomaly off Brazil, an implausible increase for a subtropical gyre location. Furthermore, the resulting sedimentation rates would be up to ~145 cm/kyr during the deglaciation, an order of magnitude higher than the average sedimentation rate for 36GGC. When our results are

NDMA formation kinetics from three pharmaceuticals in four water matrices.

Science.gov (United States)

Shen, Ruqiao; Andrews, Susan A

2011-11-01

N, N-nitrosodimethylamine (NDMA) is an emerging disinfection by-product (DBP) that has been widely detected in many drinking water systems and commonly associated with the chloramine disinfection process. Some amine-based pharmaceuticals have been demonstrated to form NDMA during chloramination, but studies regarding the reaction kinetics are largely lacking. This study investigates the NDMA formation kinetics from ranitidine, chlorphenamine, and doxylamine under practical chloramine disinfection conditions. The formation profile was monitored in both lab-grade water and real water matrices, and a statistical model is proposed to describe and predict the NDMA formation from selected pharmaceuticals in various water matrices. The results indicate the significant impact of water matrix components and reaction time on the NDMA formation from selected pharmaceuticals, and provide fresh insights on the estimation of ultimate NDMA formation potential from pharmaceutical precursors. Copyright © 2011 Elsevier Ltd. All rights reserved.

Oxoferryl-Porphyrin Radical Catalytic Intermediate in Cytochrome bd Oxidases Protects Cells from Formation of Reactive Oxygen Species*

Science.gov (United States)

Paulus, Angela; Rossius, Sebastiaan Gijsbertus Hendrik; Dijk, Madelon; de Vries, Simon

2012-01-01

The quinol-linked cytochrome bd oxidases are terminal oxidases in respiration. These oxidases harbor a low spin heme b558 that donates electrons to a binuclear heme b595/heme d center. The reaction with O2 and subsequent catalytic steps of the Escherichia coli cytochrome bd-I oxidase were investigated by means of ultra-fast freeze-quench trapping followed by EPR and UV-visible spectroscopy. After the initial binding of O2, the O–O bond is heterolytically cleaved to yield a kinetically competent heme d oxoferryl porphyrin π-cation radical intermediate (compound I) magnetically interacting with heme b595. Compound I accumulates to 0.75–0.85 per enzyme in agreement with its much higher rate of formation (∼20,000 s−1) compared with its rate of decay (∼1,900 s−1). Compound I is next converted to a short lived heme d oxoferryl intermediate (compound II) in a phase kinetically matched to the oxidation of heme b558 before completion of the reaction. The results indicate that cytochrome bd oxidases like the heme-copper oxidases break the O–O bond in a single four-electron transfer without a peroxide intermediate. However, in cytochrome bd oxidases, the fourth electron is donated by the porphyrin moiety rather than by a nearby amino acid. The production of reactive oxygen species by the cytochrome bd oxidase was below the detection level of 1 per 1000 turnovers. We propose that the two classes of terminal oxidases have mechanistically converged to enzymes in which the O–O bond is broken in a single four-electron transfer reaction to safeguard the cell from the formation of reactive oxygen species. PMID:22287551

Ozone decomposition in water studied by pulse radiolysis. 2. OH and HO4 as chain intermediates

International Nuclear Information System (INIS)

Staehelin, J.; Buehler, R.E.; Hoigne, J.

1984-01-01

Ozone decomposition in pure water involves a chain mechanism, initiated by the reaction OH - +O 3 and propogated by O 2 - and OH. In the present studies this chain is initiated by pulse radiolysis of aqueous solutions of ozone. The chain propogation steps were studied in two parts. By computer simulation of the rate curves, it is shown that from OH + O 3 and intermediate HO 4 must be formed, most likely a charge-transfer complex (HO.O 3 ), which eventually decays into HO 2 . The derived rate constants for the formation of the various species are included. The spectrum of HO 4 is derived. It is similar to the one of ozone, but the absorption coefficients are about 50% larger. In the presence of high ozone concentration, the dominant chain termination reactions are HO 4 + HO 4 and HO 4 + HO 3 . The effect on chain length, dose, overall rate, and pH and of added scavengers is described. The implications for the natural ozone decay mechanism are discussed

Reactions of stabilized Criegee Intermediates

Science.gov (United States)

Vereecken, Luc; Harder, Hartwig; Novelli, Anna

2014-05-01

Carbonyl oxides (Criegee intermediates) were proposed as key intermediates in the gas phase ozonolysis of alkenes in 1975 by Rudolf Criegee. Despite the importance of ozonolysis in atmospheric chemistry, direct observation of these intermediates remained elusive, with only indirect experimental evidence for their role in the oxidation of hydrocarbons, e.g. through scavenging experiments. Direct experimental observation of stabilized CI has only been achieved since 2008. Since then, a concerted effort using experimental and theoretical means is in motion to characterize the chemistry and kinetics of these reactive intermediates. We present the results of theoretical investigations of the chemistry of Criegee intermediates with a series of coreactants which may be of importance in the atmosphere, in experimental setups, or both. This includes the CI+CI cross-reaction, which proceeds with a rate coefficient near the collision limit and can be important in experimental conditions. The CI + alkene reactions show strong dependence of the rate coefficient depending on the coreactants, but is generally found to be rather slow. The CI + ozone reaction is sufficiently fast to occur both in experiment and the free troposphere, and acts as a sink for CI. The reaction of CI with hydroperoxides, ROOH, is complex, and leads both to the formation of oligomers, as to the formation of reactive etheroxides, with a moderately fast rate coefficient. The importance of these reactions is placed in the context of the reaction conditions in different atmospheric environments ranging from unpolluted to highly polluted.

Importance of the Gulf of Aqaba for the formation of bottom water in the Red Sea

Science.gov (United States)

Plähn, Olaf; Baschek, Burkard; Badewien, Thomas H.; Walter, Maren; Rhein, Monika

2002-08-01

Conductivity-temperature-depth tracer and direct current measurements collected in the northern Red Sea in February and March 1999 are used to study the formation of deep and bottom water in that region. Historical data showed that open ocean convection in the Red Sea can contribute to the renewal of intermediate or deep water but cannot ventilate the bottom water. The observations in 1999 showed no evidence for open ocean convection in the Red Sea during the winter 1998/1999. The overflow water from the Gulf of Aqaba was found to be the densest water mass in the northern Red Sea. An anomaly of the chlorofluorocarbon component CFC-12 observed in the Gulf of Aqaba and at the bottom of the Red Sea suggests a strong contribution of this water mass to the renewal of bottom water in the Red Sea. The CFC data obtained during this cruise are the first available for this region. Because of the new signal, it is possible for the first time to subdivide the deep water column into deep and bottom water in the northern Red Sea. The available data set also shows that the outflow water from the Gulf of Suez is not dense enough to reach down to the bottom of the Red Sea but was found about 250 m above the bottom.

Determination of water saturation in subsurface earth formations adjacent well boreholes

International Nuclear Information System (INIS)

Scott, Hubert D.

1982-01-01

There is provided a method of determining the water saturation of an earth formation surrounding a well borehole, comprising the steps of: (a) bombarding the earth formation with repetitive pulses of fast neutrons which are slowed down and thereafter engage in neutron capture reactions with materials in the vicinity of the borehole; (b) obtaining by use of a germanium gamma ray detector gamma ray spectra of the materials in the vicinity of the borehole; (c) obtaining from the gamma ray spectra a measure of the relative presence of chlorine to that of hydrogen in the formation; (d) obtaining a measure of apparent formation water salinity from the measure of relative presence of chlorine to hydrogen in the formation; and (e) obtaining the water saturation of the formation utilizing the apparent formation water salinity

The Environmental Impact of Oilfield Formation Water on a ...

African Journals Online (AJOL)

A comparative analysis of the physico-chemical parameters of treated oilfield formation water and that of a freshwater stream with no previous history of pollution from oil exploration activities was determined. The environmental impact resulting from the discharge of treated oilfield formation water into freshwater samples ...

The influence of organic materials on the near field of an intermediate level radioactive waste repository

International Nuclear Information System (INIS)

Wilkins, J.D.

1988-01-01

The influence of organic materials which are present in some intermediate level wastes on the chemistry of the near field of a radioactive waste repository is discussed. Particular attention is given to the possible formation of water soluble complexing agents as a result of the radiation field and chemical conditions. The present state of the research is reviewed. (author)

Formation of brominated trihalomethanes in chlorinated drinking-water from Lake Constance

International Nuclear Information System (INIS)

Petri, M.; Stabel, H.H.

1994-01-01

The formation of trihalomethanes (THMs) in raw water and drinking water from Lake Constance containing low amounts of DOC and bromide was studied with special emphasis on brominated trihalomethanes (Br-THMs). If the raw water was ozonated prior to chlorination, the formation of THMs was reduced by 37%, and if a rapid sandfiltration was interposed, the THM-formation was again slightly enhanced. The percentage of Br-THMs on total-THMs increased from 16% to 35% during the treatment process. In the drinking water distribution system of BWV the formation of Br-THMs and CHCl 3 was studied with respect to residence time and post-chlorination. Unless the post-chlorination was performed, the THM-formation in the distribution system resembled that obtained from laboratory studies, except for small amounts of THMs being purged due to transport in the mains and residence in the reservoirs. Post-chlorination increased CHCl 3 - and the CHBrCl 2 -formation, but there was no effect on the formation of CHBr 2 Cl and CHBr 3 . However, the total THM-concentration in the drinking water never exceeded the German drinking water standard of 10 μg/L. (orig.) [de

Towards a dynamical description of intermediate mass fragment formation in heavy-ion collisions at some tens of MeV/A

International Nuclear Information System (INIS)

Suraud, E.

1990-01-01

We briefly remind the possible dynamical scenario of fragments formation in central heavy-ion collisions at some tens of MeV/A. We discuss how present day dynamical models can describe fragment formation. We show that particle methods provide a reasonable solution of Boltzman-like equations. We next turn to the Boltzmann-Langevin formalism which gives a well defined framework for the understanding of Intermediate Mass Fragments formation. We present a first numerical solution of this equation and show the importance of fluctuations in the dynamics of the collision. We finally apply the formalism to the onset of multifragmentation in the 40 Ca + 40 Ca system between 20 and 60 MeV/A beam energy

Characterization of Formation Water Constituents and the Effect of ...

African Journals Online (AJOL)

Michael Horsfall

ABSTRACT: The research work examined the constituents of formation water and fresh water dilution effects from a land location in the Niger Delta Area of Nigeria. Some selected physicochemical and microbiological analyses were determined at ambient temperature (82oF) and formation temperature (185oF). Analysis of ...

Predicting hydrocarbon potential of an earth formation underlying water

International Nuclear Information System (INIS)

Damaison, G.J.; Kaplan, I.R.

1981-01-01

A method for the on-site collection and examination of small concentrations of a carbonaceous gas, e.g. methane, dissolved in a body of water overlying an earth formation to predict hydrocarbon potential of the earth formation under the body of water, the formation being a source of carbonaceous gas, comprises at a known geographic location sampling the water at a selected flow rate and at a selected depth; continuously vacuum separating the water into liquid and gas phases; separating a selected carbonaceous gas from interfering gas species in the presence of an air carrier vented to atmosphere at a known flow rate; and quantitatively oxidizing the selected gas and then cryogenically trapping an oxidant thereof in the presence of said air carrier to provide for an accurate isotopic examination. (author)

Water Transfer Characteristics during Methane Hydrate Formation Processes in Layered Media

Directory of Open Access Journals (Sweden)

Yousheng Deng

2011-08-01

Full Text Available Gas hydrate formation processes in porous media are always accompanied by water transfer. To study the transfer characteristics comprehensively, two kinds of layered media consisting of coarse sand and loess were used to form methane hydrate in them. An apparatus with three PF-meter sensors detecting water content and temperature changes in media during the formation processes was applied to study the water transfer characteristics. It was experimentally observed that the hydrate formation configurations in different layered media were similar; however, the water transfer characteristics and water conversion ratios were different.

Influence of nitrogen source on NDMA formation during chlorination of diuron.

Science.gov (United States)

Chen, Wei-Hsiang; Young, Thomas M

2009-07-01

N-Nitrosodimethylamine (NDMA) is formed during chlorination of water containing the herbicide diuron (N'-(3,4-dichlorophenyl)-N,N-dimethylurea) but formation is greatly enhanced in the presence of ammonia (chloramination). Groundwater impacted by agricultural runoff may contain diuron and relatively high total nitrogen concentrations; this study examines the impact of the nitrogen form (ammonium, nitrite or nitrate) on NDMA formation during chlorination of such waters. NDMA formation during chlorination of diuron increased in the order nitriteNDMA formation in the presence of ammonium. Nitrate unexpectedly enhanced nitrosation of diuron derivatives to form NDMA compared to the cases of no added nitrogen or nitrite addition. Nitrite addition is less effective because it consumes more chlorine and produces intermediates that react rapidly with diuron and its aromatic byproducts. Differences between surface water and groundwater in nitrogen forms and concentrations and disinfection approaches suggest strategies to reduce NDMA formation should vary with drinking water source.

Variation of the cold intermediate water in the Black Sea exit of the Strait of Istanbul (Bosphorus and its transfer through the strait

Directory of Open Access Journals (Sweden)

Huseyin Yuce

2012-04-01

Full Text Available The cold intermediate water (CIW, T < 8°C entering the Strait of Istanbul and its variation along the strait have been studied by using monthly conductivity-temperature-depth (CTDdata sets collected during the period from 1996 to 2000. In the northern exit of the strait, CIW is located between the seasonal thermocline and Mediterranean water originating from the lowerlayer of the Sea of Marmara. The thickness of CIW decreases fromApril to October. In the Strait of Istanbul, CIW is observedas a layer of temperature < 14$^{circ}$C. The thickness of thismodified cold intermediate water flowing southwards with the upper layer decreases, while its temperature increases along thestrait due to mixing with adjacent water. In the southern exit of the strait, the modified cold intermediate water is observed during the period from May to October. If CIW exists in the Black Sea exit region of the strait, modified cold water is found inthe Marmara exit region during the same period. The distribution of CIW in the Strait of Istanbul contributes to our understanding of the dynamics of the strait, especially in the summer months.

NDMA formation during drinking water treatment: A multivariate analysis of factors influencing formation.

Science.gov (United States)

Leavey-Roback, Shannon L; Sugar, Catherine A; Krasner, Stuart W; Suffet, Irwin H Mel

2016-05-15

The formation of the carcinogen N-nitrosodimethylamine (NDMA) during drinking water treatment has raised concerns in the drinking water industry. Many bench-scale laboratory tests and pilot plant studies have been completed to try to determine which factors during water treatment increase or decrease the amount of NDMA formed in drinking water. This study used data from over 20 drinking water treatment plants in the United States and Canada to determine which factors are most highly correlated with the NDMA concentration in delivered water using a mixed effects model with a random intercept. This type of analysis has not been used previously with trihalomethane (THM) models due to the fact that those studies did not sample such a large number and range of plants as was done in this NDMA study. Ultraviolet absorbance at 254 nm (UV254) in the plant influent and pre-chlorination time used at the plant were highly correlated in all models with NDMA concentration in finished water as well as the percentage change between NDMA formation potential in the plant influent and actual formation in the finished water. Specifically, an increase in UV254 absorbance in a model was associated with an increase in NDMA and an increase in pre-chlorination time in a model was associated with a decrease in NDMA. Other water quality parameters including sucralose concentration in the plant influent, polyDADMAC polymer dose, pH, and chlorine-to-ammonia weight ratio used in the plant were also correlated with NDMA concentration in the distribution system. Lastly, NDMA precursor loading was correlated with the use of polyDADMAC (where precursors were added) and the use of ozone and granular activated carbon (GAC) treatment (where precursors were removed). Copyright © 2016 Elsevier Ltd. All rights reserved.

Search for intermediate vector bosons

International Nuclear Information System (INIS)

Klajn, D.B.; Rubbia, K.; Meer, S.

1983-01-01

Problem of registration and search for intermediate vector bosons is discussed. According to weak-current theory there are three intermediate vector bosons with +1(W + )-1(W - ) and zero (Z 0 ) electric charges. It was suggested to conduct the investigation into particles in 1976 by cline, Rubbia and Makintair using proton-antiproton beams. Major difficulties of the experiment are related to the necessity of formation of sufficient amount of antiparticles and the method of antiproton beam ''cooling'' for the purpose of reduction of its random movements. The stochastic method was suggested by van der Meer in 1968 as one of possible cooling methods. Several large detectors were designed for searching intermediate vector bosons

Numerical simulation of water and sand blowouts when penetrating through shallow water flow formations in deep water drilling

Science.gov (United States)

Ren, Shaoran; Liu, Yanmin; Gong, Zhiwu; Yuan, Yujie; Yu, Lu; Wang, Yanyong; Xu, Yan; Deng, Junyu

2018-02-01

In this study, we applied a two-phase flow model to simulate water and sand blowout processes when penetrating shallow water flow (SWF) formations during deepwater drilling. We define `sand' as a pseudo-component with high density and viscosity, which can begin to flow with water when a critical pressure difference is attained. We calculated the water and sand blowout rates and analyzed the influencing factors from them, including overpressure of the SWF formation, as well as its zone size, porosity and permeability, and drilling speed (penetration rate). The obtained data can be used for the quantitative assessment of the potential severity of SWF hazards. The results indicate that overpressure of the SWF formation and its zone size have significant effects on SWF blowout. A 10% increase in the SWF formation overpressure can result in a more than 90% increase in the cumulative water blowout and a 150% increase in the sand blowout when a typical SWF sediment is drilled. Along with the conventional methods of well flow and pressure control, chemical plugging, and the application of multi-layer casing, water and sand blowouts can be effectively reduced by increasing the penetration rate. As such, increasing the penetration rate can be a useful measure for controlling SWF hazards during deepwater drilling.

Site study plan for intermediate hydrology clusters tests wells Deaf Smith County Site, Texas

International Nuclear Information System (INIS)

1988-01-01

To characterize the geologic, geochemical, and hydrologic characteristics of intermediate-depth formations at the proposed Deaf Smith County, Texas, repository site, wells called Intermediate Hydrology clusters will test the Dewey Lake, Alibates, Salado, Yates, Upper and Lower Seven Rivers, and Queen Grayburg Formations. Sixteen wells will be installed at six locations. One location will have four wills, two locations will have three wells, and three locations will have two wells for a total of 16 wells. Testing of the formations is to proceed from the bottom up, with 2-day pumping tests at the less permeable formations. Tracer tests and tests for verticall hydraulic properties will be designed and performed after other hydrologic tests are completed. After testing, selected wells are to be completed as single or possibly dual monitoring wells to observe water-level trends. To develop a hydrogeologic testing plan, the response of each formation to potential testing procedures was evaluated using design values and an assumend range for hydraulic parameters. These evaluations indicate that hydraulic properties of a sandy zone of the Dockum, the lower Sever Rivers, and possibly the Alibates and Queen/Grayburg can be determined by pumping tests. Standard of shut-in slug tests must be conducted in the remaining formations. Tests of very long duration would be required to determine the verticla properties of less permeable formations. Tracer tests would also require weeks or months. 61 figs., 34 refs., 4 tabs

Language in use intermediate : classroom book

CERN Document Server

Doff, Adrian

1995-01-01

ach of the four levels comprises about 80 hours of class work, with additional time for the self-study work. The Teacher's Book contains all the pages from the Classroom Book, with interleaved teaching notes including optional activities to cater for different abilities. There is a video to accompany the Beginner, Pre-intermediate and Intermediate levels. Each video contains eight stimulating and entertaining short programmes, as well as a booklet of photocopiable activities. Free test material is available in booklet and web format for Beginner and Pre-intermediate levels. Visit www.cambridge.org/elt/liu or contact your local Cambridge University Press representative.

Language in use intermediate : teacher's book

CERN Document Server

Doff, Adrian

1998-01-01

Each of the four levels comprises about 80 hours of class work, with additional time for the self-study work. The Teacher's Book contains all the pages from the Classroom Book, with interleaved teaching notes including optional activities to cater for different abilities. There is a video to accompany the Beginner, Pre-intermediate and Intermediate levels. Each video contains eight stimulating and entertaining short programmes, as well as a booklet of photocopiable activities. Free test material is available in booklet and web format for Beginner and Pre-intermediate levels. Visit www.cambridge.org/elt/liu or contact your local Cambridge University Press representative.

Influence of Nitrogen Source on NDMA Formation during Chlorination of Diuron

Science.gov (United States)

Chen, Wei-Hsiang; Young, Thomas M.

2009-01-01

N-Nitrosodimethylamine (NDMA) is formed during chlorination of water containing the herbicide diuron (N′-(3,4-dichlorophenyl)-N, N-dimethylurea) but formation is greatly enhanced in the presence of ammonia (chloramination). Groundwater impacted by agricultural runoff may contain diuron and relatively high total nitrogen concentrations; this study examines the impact of the nitrogen form (ammonium, nitrite or nitrate) on NDMA formation during chlorination of such waters. NDMA formation during chlorination of diuron increased in the order nitrite diuron dose. Formation of dichloramine seemed to fully explain enhanced NDMA formation in the presence of ammonium. Nitrate unexpectedly enhanced nitrosation of diuron derivatives to form NDMA compared to the cases of no added nitrogen or nitrite addition. Nitrite addition is less effective because it consumes more chlorine and produces intermediates that react rapidly with diuron and its aromatic byproducts. Differences between surface and groundwater in nitrogen forms and concentrations and disinfection approaches, suggest strategies to reduce NDMA formation should vary with drinking water source. PMID:19457535

Conversion of tritium gas to tritiated water

International Nuclear Information System (INIS)

Papagiannakopoulos, P.J.; Easterly, C.E.

1979-05-01

The mechanisms of conversion of tritium gas to tritiated water (HTO) have been examined for several tritium gaseous mixtures. The physical and chemical processes involved in the self-radiolysis of such mixtures have been analyzed and the kinetics involved in the formation of HTO has been presented. It has been determined that the formation of the H and/or OH free radicals, as intermediate species, are of significance in the formation of HTO. Therefore, the problem of reducing the rate of formation of tritiated water in a mixture of gaseous tritium with atmospheric components is one of finding an effective scavenger for the H and/or OH free radicals

Freshening of Antarctic Intermediate Water in the South Atlantic Ocean in 2005–2014

OpenAIRE

Yao, Wenjun; Shi, Jiuxin

2016-01-01

Basin-scaled freshening of Antarctic Intermediate Water (AAIW) is reported to have dominated South Atlantic Ocean during period from 2005 to 2014, as shown by the gridded monthly means Argo (Array for Real-time Geostrophic Oceanography) data. The relevant investigation was also revealed by two transatlantic occupations of repeated section along 30° S, from World Ocean Circulation Experiment Hydrographic Program. Freshening of the AAIW was compensated by the opposing salinity increase o...

The influence of organic materials on the near field of an intermediate level waste radioactive waste repository

International Nuclear Information System (INIS)

Wilkins, J.D.

1988-02-01

The influence of organic materials, which are present in some intermediate level wastes, on the chemistry of the near field of a radioactive waste repository is discussed. Particular attention is given to the possible formation of water soluble complexing agents formed as a result of the radiation field and chemical conditions. The present state of the research is reviewed. (author)

Role of the reaction of stabilized Criegee intermediates with peroxy radicals in particle formation and growth in air.

Science.gov (United States)

Zhao, Yue; Wingen, Lisa M; Perraud, Véronique; Greaves, John; Finlayson-Pitts, Barbara J

2015-05-21

Ozonolysis of alkenes is an important source of secondary organic aerosol (SOA) in the atmosphere. However, the mechanisms by which stabilized Criegee intermediates (SCI) react to form and grow the particles, and in particular the contributions from oligomers, are not well understood. In this study, ozonolysis of trans-3-hexene (C6H12), as a proxy for small alkenes, was investigated with an emphasis on the mechanisms of particle formation and growth. Ozonolysis experiments were carried out both in static Teflon chambers (18-20 min reaction times) and in a glass flow reactor (24 s reaction time) in the absence and presence of OH or SCI scavengers, and under different relative humidity (RH) conditions. The chemical composition of polydisperse and size-selected SOA particles was probed using different mass spectrometric techniques and infrared spectroscopy. Oligomers having SCI as the chain unit are found to be the dominant components of such SOA particles. The formation mechanism for these oligomers suggested by our results follows the sequential addition of SCI to organic peroxy (RO2) radicals, in agreement with previous studies by Moortgat and coworkers. Smaller particles are shown to have a relatively greater contribution from longer oligomers. Higher O/C ratios are observed in smaller particles and are similar to those of oligomers resulting from RO2 + nSCI, supporting a significant role for longer oligomers in particle nucleation and early growth. Under atmospherically relevant RH of 30-80%, water vapor suppresses oligomer formation through scavenging SCI, but also enhances particle nucleation. Under humid conditions, or in the presence of formic or hydrochloric acid as SCI scavengers, peroxyhemiacetals are formed by the acid-catalyzed particle phase reaction between oligomers from RO2 + nSCI and a trans-3-hexene derived carbonyl product. In contrast to the ozonolysis of trans-3-hexene, oligomerization involving RO2 + nSCI does not appear to be prevalent in the

Influence of surfactants on gas-hydrate formation' kinetics in water-oil emulsion

Science.gov (United States)

Zemenkov, Yu D.; Shirshova, A. V.; Arinstein, E. A.; Shuvaev, A. N.

2018-05-01

The kinetics of gas hydrate formation of propane in a water-oil emulsion is experimentally studied when three types of surfactants (SAA (surface acting agent)) - anionic type emulsifiers - are added to the aqueous phase. It is shown that all three types of surfactants decelerate the growth of the gas-hydrate in the emulsion and can be considered as anti-agglutinating and kinetic low-dose inhibitors. The most effective inhibitor of hydrate formation in water-oil emulsion of SV-102 surfactant was revealed. For comparison, experimental studies of gas-hydrate formation under the same conditions for bulk water have been carried out. It is shown that in bulk water, all the surfactants investigated act as promoters (accelerators) of hydrate formation. A qualitative explanation of the action mechanisms of emulsifiers in the process of gas-hydrate formation in water-oil emulsion is given.

Freshening of Antarctic Intermediate Water in the South Atlantic Ocean in 2005–2014

OpenAIRE

W. Yao; J. Shi; X. Zhao

2017-01-01

Basin-scale freshening of Antarctic Intermediate Water (AAIW) is reported to have occurred in the South Atlantic Ocean during the period from 2005 to 2014, as shown by the gridded monthly means of the Array for Real-time Geostrophic Oceanography (Argo) data. This phenomenon was also revealed by two repeated transects along a section at 30° S, performed during the World Ocean Circulation Experiment Hydrographic Program. Freshening of the AAIW was compensated for by a salinity...

Water states and types of water in materials from different argillaceous formations

International Nuclear Information System (INIS)

Fernandez, A.M.; Melon, A.

2010-01-01

Document available in extended abstract form only. Depending of their structure and degree of compaction, clays can be hydrated by a variable amount of water molecules in the inter-lamellar space and on external surfaces. Due to the fact that the structure and nature of water molecules (properties of liquid water) is influenced by the clay surfaces; different types of waters are involved in clayey systems (internal/external water, adsorbed/free water) giving a double porosity structure. The water volume accessible to ions is a key parameter in order to determine the pore water chemistry affecting the radionuclide transport in clay-rocks. In the case of argillaceous formations, natural consolidation induces significant physical and structural changes to clays as a function of time, leading to a progressive compaction and agglomeration of particles, reduction of crystallinity and an increase of micro-strain, which affects both the tetrahedral and octahedral layers. Structure and dynamics of water are modified when water molecules are close to interfaces or confined in porous spaces. At high degrees of compaction, the diffusive transport of the solvated ions and the solvent molecules in clays is substantially retarded compared with the free electrolyte solution because of the surface complexation of ions and the strong ordering of solvent molecules at the solid-liquid interface. Besides, mud-rocks contain a variable amount of different types of clays, such as illite, kaolinite, chlorites, smectite and illite/smectite mixed layers; as well as other main and accessory minerals which influence also the amount of water adsorbed and types of waters in these systems. Structural and dynamic properties of water confined among basal planes of clays have been extensively studied by means of water adsorption isotherms, neutron scattering, molecular dynamics (MD) and Monte- Carlo simulations. However, most of the works are related to purified clays and dispersed systems. In real

Language in use intermediate : self-study workbook

CERN Document Server

Doff, Adrian

1994-01-01

Each of the four levels comprises about 80 hours of class work, with additional time for the self-study work. The Teacher's Book contains all the pages from the Classroom Book, with interleaved teaching notes including optional activities to cater for different abilities. There is a video to accompany the Beginner, Pre-intermediate and Intermediate levels. Each video contains eight stimulating and entertaining short programmes, as well as a booklet of photocopiable activities. Free test material is available in booklet and web format for Beginner and Pre-intermediate levels. Visit www.cambridge.org/elt/liu or contact your local Cambridge University Press representative.

Volatile and intermediate volatility organic compounds in suburban Paris: variability, origin and importance for SOA formation

International Nuclear Information System (INIS)

Ait-Helal, W.; Borbon, A.; Beekmann, M.; Doussin, J.F.; Durand-Jolibois, R.; Grand, N.; Michoud, V.; Miet, K.; Perrier, S.; Siour, G.; Zapf, P.; Sauvage, S.; Fronval, I.; Leonardis, T.; Locoge, N.; Gouw, J.A. de; Colomb, A.; Gros, V.; Lopez, M.

2014-01-01

Measurements of gaseous and particulate organic carbon were performed during the MEGAPOLI experiments, in July 2009 and January-February 2010, at the SIRTA observatory in suburban Paris. Measurements comprise primary and secondary volatile organic compounds (VOCs), of both anthropogenic and biogenic origins, including C12-C16 n-alkanes of intermediate volatility (IVOCs), suspected to be efficient precursors of secondary organic aerosol (SOA). The time series of gaseous carbon are generally consistent with times series of particulate organic carbon at regional scale, and are clearly affected by meteorology and air mass origin. Concentration levels of anthropogenic VOCs in urban and suburban Paris were surprisingly low (2-963 ppt) compared to other mega-cities worldwide and to rural continental sites. Urban enhancement ratios of anthropogenic VOC pairs agree well between the urban and suburban Paris sites, showing the regional extent of anthropogenic sources of similar composition. Contrary to other primary anthropogenic VOCs (aromatics and alkanes), IVOCs showed lower concentrations in winter (≤ 5 ppt) compared to summer (13-27 ppt), which cannot be explained by the gas-particle partitioning theory. Higher concentrations of most oxygenated VOCs in winter (18-5984 ppt) suggest their dominant primary anthropogenic origin. The respective role of primary anthropogenic gaseous compounds in regional SOA formation was investigated by estimating the SOA mass concentration expected from the anthropogenic VOCs and IVOCs (I/VOCs) measured at SIRTA. From an integrated approach based on emission ratios and SOA yields, 38% of the SOA measured at SIRTA is explained by the measured concentrations of I/VOCs, with a 2% contribution by C12-C16 n-alkane IVOCs. From the results of an alternative time-resolved approach, the average IVOC contribution to SOA formation is estimated to be 7 %, which is half of the average contribution of the traditional aromatic compounds (15 %). Both

Thermal decomposition of barium ferrate(VI): Mechanism and formation of Fe{sup IV} intermediate and nanocrystalline Fe{sub 2}O{sub 3} and ferrite

Energy Technology Data Exchange (ETDEWEB)

Machala, Libor, E-mail: libor.machala@upol.cz [Regional Centre of Advanced Technologies and Materials, Department of Experimental Physics, Faculty of Science, Palacký University, Olomouc (Czech Republic); Sharma, Virender K. [Department of Environmental and Occupational Health, School of Public Health, Texas A& M University, 1266 TAMU, College Station, TX 77843 (United States); Kuzmann, Ernö; Homonnay, Zoltán [Institute of Chemistry, Eötvös Loránd University, Budapest (Hungary); Filip, Jan; Kralchevska, Radina P. [Regional Centre of Advanced Technologies and Materials, Department of Experimental Physics, Faculty of Science, Palacký University, Olomouc (Czech Republic)

2016-05-25

Simple high-valent iron-oxo species, ferrate(VI) (Fe{sup VI}O{sub 4}{sup 2−}, Fe(VI)) has applications in energy storage, organic synthesis, and water purification. Of the various salts of Fe(VI), barium ferrate(VI) (BaFeO{sub 4}) has also a great potential as a battery material. This paper presents the thermal decomposition of BaFeO{sub 4} in static air and nitrogen atmosphere, monitored by combination of thermal analysis, Mössbauer spectroscopy, X-ray powder diffraction, and electron-microscopic techniques. The formation of Fe{sup IV} species in the form of BaFeO{sub 3} was found to be the primary decomposition product of BaFeO{sub 4} at temperature around 190 °C under both studied atmospheres. BaFeO{sub 3} was unstable in air reacting with CO{sub 2} to form barium carbonate and speromagnetic amorphous iron(III) oxide nanoparticles (<5 nm). Above 600 °C, a solid state reaction between BaCO{sub 3} and Fe{sub 2}O{sub 3} occurred, leading to the formation of barium ferrite nanoparticles, BaFe{sub 2}O{sub 4} (20–100 nm). - Highlights: • We explained the mechanism of thermal decomposition of barium ferrate(VI). • We confirmed the formation of Fe(IV) intermediate phase during the decomposition. • The mechanism of the decomposition is influenced by a presence of carbon dioxide.

Role of Chlorine Dioxide in N-Nitrosodimethylamine Formation from Oxidation of Model Amines.

Science.gov (United States)

Gan, Wenhui; Bond, Tom; Yang, Xin; Westerhoff, Paul

2015-10-06

N-Nitrosodimethylamine (NDMA) is an emerging disinfection byproduct, and we show that use of chlorine dioxide (ClO2) has the potential to increase NDMA formation in waters containing precursors with hydrazine moieties. NDMA formation was measured after oxidation of 13 amines by monochloramine and ClO2 and pretreatment with ClO2 followed by postmonochloramination. Daminozide, a plant growth regulator, was found to yield 5.01 ± 0.96% NDMA upon reaction with ClO2, although no NDMA was recorded during chloramination. The reaction rate was estimated to be ∼0.0085 s(-1), and on the basis of our identification by mass spectrometry of the intermediates, the reaction likely proceeds via the hydrolytic release of unsymmetrical dimethylhydrazine (UDMH), with the hydrazine structure a key intermediate in NDMA formation. The presence of UDMH was confirmed by gas chromatography-mass spectrometry analysis. For 10 of the 13 compounds, ClO2 preoxidation reduced NDMA yields compared with monochloramination alone, which is explained by our measured release of dimethylamine. This work shows potential preoxidation strategies to control NDMA formation may not impact all organic precursors uniformly, so differences might be source specific depending upon the occurrence of different precursors in source waters. For example, daminozide is a plant regulator, so drinking water that is heavily influenced by upstream agricultural runoff could be at risk.

The radiolytic formation of nitric acid in argon/air/water systems

International Nuclear Information System (INIS)

May, R.; Stinchcombe, D.; White, H.P.

1992-01-01

The extent of nitric acid formation in the γ-radiolysis of argon/air/water mixtures has been assessed. The yields of nitric acid are found to increase as water vapour pressure is increased but are lower in the presence of a discrete water phase. G values for the formation of nitric acid from argon/air mixtures based on energy absorbed in the air are increased in the presence of argon but the yields in an atmosphere of argon containing small amounts of moist air are smaller than from an atmosphere of moist air alone. The G value for nitric acid formation from pure air in the presence of a distinct water phase is 2, based on energy absorbed in the air. (author)

Mechanisms of deterioration of intermediate moisture food systems

Science.gov (United States)

Labuza, T. P.

1972-01-01

A study of shelf stability in intermediate moisture foods was made. Major efforts were made to control lipid oxidation and nonenzymatic browning. In order to determine means of preventing these reactions, model systems were developed having the same water activity content relationship of intermediate moisture foods. Models were based on a cellulose-lipid and protein-lipid system with glycerol added as the humectant. Experiments with both systems indicate that lipid oxidation is promoted significantly in the intermediate moisture range. The effect appeared to be related to increased mobility of either reactants or catalysts, since when the amount of water in the system reached a level where capillary condensation occurred and thus free water was present, the rates of oxidation increased. With added glycerol, which is water soluble and thus increases the amount of mobile phase, the increase in oxidation rate occurs at a lower relative humidity. The rates of oxidation were maximized at 61% RH and decreased again at 75% RH probably due to dilution. No significant non-enzymatic browning occurred in the protein-lipid systems. Prevention of oxidation by the use of metal chelating agents was enhanced in the cellulose system, whereas, with protein present, the lipid soluble chain terminating antioxidants (such as BHA) worked equally as well. Preliminary studies of foods adjusted to the intermediate moisture range bear out the results of oxidation in model systems. It can be concluded that for most fat containing intermediate moisture foods, rancidity will be the reaction most limiting stability.

Reduction of Bromate Formation During Ozonation of Drinking Water

DEFF Research Database (Denmark)

Antoniou, Maria; Sichel, C.; Andre, K.

This study focused on the prevention of carcinogenic bromate formation during ozonation of tap water from the DTU university campus. To achieve this, different pre-treatments including pH-adjustment, ammonia addition and chlorine-ammonia addition, were tested. Formation of bromated was drastically...

Four groups of new aromatic halogenated disinfection byproducts: effect of bromide concentration on their formation and speciation in chlorinated drinking water.

Science.gov (United States)

Pan, Yang; Zhang, Xiangru

2013-02-05

Bromide is naturally present in source waters worldwide. Chlorination of drinking water can generate a variety of chlorinated and brominated disinfection byproducts (DBPs). Although substantial efforts have been made to examine the effect of bromide concentration on the formation and speciation of halogenated DBPs, almost all previous studies have focused on trihalomethanes and haloacetic acids. Given that about 50% of total organic halogen formed in chlorination remains unknown, it is still unclear how bromide concentration affects the formation and speciation of the new/unknown halogenated DBPs. In this study, chlorinated drinking water samples with different bromide concentrations were prepared, and a novel approach-precursor ion scan using ultra performance liquid chromatography/electrospray ionization-triple quadrupole mass spectrometry-was adopted for the detection and identification of polar halogenated DBPs in these water samples. With this approach, 11 new putative aromatic halogenated DBPs were identified, and they were classified into four groups: dihalo-4-hydroxybenzaldehydes, dihalo-4-hydroxybenzoic acids, dihalo-salicylic acids, and trihalo-phenols. A mechanism for the formation of the four groups of new aromatic halogenated DBPs was proposed. It was found that increasing the bromide concentration shifted the entire polar halogenated DBPs as well as the four groups of new DBPs from being less brominated to being more brominated; these new aromatic halogenated DBPs might be important intermediate DBPs formed in drinking water chlorination. Moreover, the speciation of the four groups of new DBPs was modeled: the speciation patterns of the four groups of new DBPs well matched those determined from the model equations, and the reactivity differences between HOBr and HOCl in reactions forming the four groups of new DBPs were larger than those in reactions forming trihalomethanes and haloacetic acids.

Formation of halogenated C-, N-DBPs from chlor(am)ination and UV irradiation of tyrosine in drinking water

International Nuclear Information System (INIS)

Chu Wenhai; Gao Naiyun; Krasner, Stuart W.; Templeton, Michael R.; Yin Daqiang

2012-01-01

The formation of regulated and emerging halogenated carbonaceous (C-) and nitrogenous disinfection by-products (N-DBPs) from the chlor(am)ination and UV irradiation of tyrosine (Tyr) was investigated. Increased chlorine contact time and/or Cl 2 /Tyr ratio increased the formation of most C-DBPs, with the exception of 4-chlorophenol, dichloroacetonitrile, and dichloroacetamideChloroform and dichloroacetic acid increased with increasing pH, dichloroacetonitrile first increased and then decreased, and other DBPs had maximum yields at pH 7 or 8. The addition of ammonia significantly reduced the formation of most C-DBPs but increased 4-chlorophenol, dichloroacetonitrile, dichloroacetamide, and trichloroacetonitrile yields for short prechlorination contact times before dosing ammonia. When UV irradiation and chlorination were performed simultaneously, the concentrations of the relatively stable C-DBPs increased, and the concentrations of dichloroacetonitrile, dichloroacetamide, and 4-chlorophenol decreased with increasing UV dose. This information was used to develop a mechanistic model for the formation of intermediate DBPs and end products from the interaction of disinfectants with tyrosine. Highlights: ► Increased contact time and/or Cl 2 /Tyr decreased the formation of some N-DBPs. ► Changing the pH of disinfection decreases the formation of some N-DBPs. ► N-DBP yields increased for short prechlorination contact time before dosing ammonia. ► Low pressure UV before chlorination did not impact the formation of DBPs from Tyr. ► A novel integrated formation pathway of halogenated C-, N-DBPs is proposed. - Exploring the integrated formation mechanism of regulated and emerging highly toxic DBPs, which is expected to preferably reduce their occurrence in drinking water.

Origin and evolution of formation water at the Jujo-Tecominoacan oil reservoir, Gulf of Mexico. Part 2: Isotopic and field-production evidence for fluid connectivity

Energy Technology Data Exchange (ETDEWEB)

Birkle, Peter, E-mail: birkle@iie.org.mx [Instituto de Investigaciones Electricas (IIE), Gerencia de Geotermia, Cuernavaca 62490, Morelos (Mexico); Garcia, Bernardo Martinez; Milland Padron, Carlos M. [PEMEX Exploracion y Produccion, Region Sur, Activo Integral Bellota-Jujo, Diseno de Explotacion, Cardenas, Tabasco (Mexico); Eglington, Bruce M. [Saskatchewan Isotope Laboratory, University of Saskatchewan, Saskatoon, Canada SK S7N 5E2 (Canada)

2009-04-15

The chemical and isotopic characterization of formation water from 18 oil production wells, extracted from 5200 to 6100 m b.s.l. at the Jujo-Tecominoacan carbonate reservoir in SE-Mexico, and interpretations of historical production records, were undertaken to determine the origin and hydraulic behavior of deep groundwater systems. The infiltration of surface water during Late Pleistocene to Early Holocene time is suggested by {sup 14}C-concentrations from 2.15 to 31.86 pmC, and by {sup 87}Sr/{sup 86}Sr-ratios for high-salinity formation water (0.70923-0.70927) that are close to the composition of Holocene to modern seawater. Prior to infiltration, the super-evaporation of seawater reached maximum TDS concentrations of 385 g/L, with lowest {delta}{sup 18}O values characterizing the most hypersaline samples. Minor deviations of formation water and dolomite host rocks from modern and Jurassic {sup 87}Sr/{sup 86}Sr-seawater composition, respectively, suggest ongoing water-rock interaction, and partial isotopic equilibration between both phases. The abundance of {sup 14}C in all sampled formation water, {sup 87}Sr/{sup 86}Sr-ratios for high-salinity water close to Holocene - present seawater composition, a water salinity distribution that is independent of historic water-cut, and a total water extraction volume of 2.037 MMm{sup 3} (1/83-4/07) excludes a connate, oil-leg origin for the produced water of the Jurassic-Cretaceous mudstone-dolomite sequence. Temporal fluctuations of water chemistry in production intervals, the accelerated migration of water fronts from the reservoir flanks, and isotopic mixing trends between sampled wells confirms the existence of free aquifer water below oil horizons. Vertical and lateral hydraulic mobility has probably been accelerated by petroleum extraction. The combination of interpreting historical fluctuations of salinity and water percentage in production wells with chemical-isotopic analysis of formation water resulted in a

Origin and evolution of formation water at the Jujo-Tecominoacan oil reservoir, Gulf of Mexico. Part 2: Isotopic and field-production evidence for fluid connectivity

International Nuclear Information System (INIS)

Birkle, Peter; Garcia, Bernardo Martinez; Milland Padron, Carlos M.; Eglington, Bruce M.

2009-01-01

The chemical and isotopic characterization of formation water from 18 oil production wells, extracted from 5200 to 6100 m b.s.l. at the Jujo-Tecominoacan carbonate reservoir in SE-Mexico, and interpretations of historical production records, were undertaken to determine the origin and hydraulic behavior of deep groundwater systems. The infiltration of surface water during Late Pleistocene to Early Holocene time is suggested by 14 C-concentrations from 2.15 to 31.86 pmC, and by 87 Sr/ 86 Sr-ratios for high-salinity formation water (0.70923-0.70927) that are close to the composition of Holocene to modern seawater. Prior to infiltration, the super-evaporation of seawater reached maximum TDS concentrations of 385 g/L, with lowest δ 18 O values characterizing the most hypersaline samples. Minor deviations of formation water and dolomite host rocks from modern and Jurassic 87 Sr/ 86 Sr-seawater composition, respectively, suggest ongoing water-rock interaction, and partial isotopic equilibration between both phases. The abundance of 14 C in all sampled formation water, 87 Sr/ 86 Sr-ratios for high-salinity water close to Holocene - present seawater composition, a water salinity distribution that is independent of historic water-cut, and a total water extraction volume of 2.037 MMm 3 (1/83-4/07) excludes a connate, oil-leg origin for the produced water of the Jurassic-Cretaceous mudstone-dolomite sequence. Temporal fluctuations of water chemistry in production intervals, the accelerated migration of water fronts from the reservoir flanks, and isotopic mixing trends between sampled wells confirms the existence of free aquifer water below oil horizons. Vertical and lateral hydraulic mobility has probably been accelerated by petroleum extraction. The combination of interpreting historical fluctuations of salinity and water percentage in production wells with chemical-isotopic analysis of formation water resulted in a successful method to distinguish four groundwater bodies

Intermediate energy data

International Nuclear Information System (INIS)

Koning, A.J.; Fukahori, T.; Hasegawa, A.

1998-01-01

Subgroup 13 (SG13) on Intermediate Energy Nuclear data was formed by NEA Nuclear Science Committee to solve common problems of these types of data for nuclear applications. An overview is presented in this final report of the present activities of SG13, including data needs, high-priority nuclear data request list (nuclides), compilation of experimental data, specialists meetings and benchmarks, data formats and data libraries. Some important accomplishments are summarized, and recommendations are presented. (R.P.)

The temperature dependence of intermediate range oxygen-oxygen correlations in liquid water

International Nuclear Information System (INIS)

Schlesinger, Daniel; Pettersson, Lars G. M.; Wikfeldt, K. Thor; Skinner, Lawrie B.; Benmore, Chris J.; Nilsson, Anders

2016-01-01

We analyze the recent temperature dependent oxygen-oxygen pair-distribution functions from experimental high-precision x-ray diffraction data of bulk water by Skinner et al. [J. Chem. Phys. 141, 214507 (2014)] with particular focus on the intermediate range where small, but significant, correlations are found out to 17 Å. The second peak in the pair-distribution function at 4.5 Å is connected to tetrahedral coordination and was shown by Skinner et al. to change behavior with temperature below the temperature of minimum isothermal compressibility. Here we show that this is associated also with a peak growing at 11 Å which strongly indicates a collective character of fluctuations leading to the enhanced compressibility at lower temperatures. We note that the peak at ∼13.2 Å exhibits a temperature dependence similar to that of the density with a maximum close to 277 K or 4 °C. We analyze simulations of the TIP4P/2005 water model in the same manner and find excellent agreement between simulations and experiment albeit with a temperature shift of ∼20 K.

The temperature dependence of intermediate range oxygen-oxygen correlations in liquid water

Energy Technology Data Exchange (ETDEWEB)

Schlesinger, Daniel; Pettersson, Lars G. M., E-mail: Lars.Pettersson@fysik.su.se [Department of Physics, AlbaNova University Center, Stockholm University, SE-106 91 Stockholm (Sweden); Wikfeldt, K. Thor [Department of Physics, AlbaNova University Center, Stockholm University, SE-106 91 Stockholm (Sweden); Science Institute, University of Iceland, VR-III, 107 Reykjavik (Iceland); Skinner, Lawrie B.; Benmore, Chris J. [X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Nilsson, Anders [Department of Physics, AlbaNova University Center, Stockholm University, SE-106 91 Stockholm (Sweden); Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States)

2016-08-28

We analyze the recent temperature dependent oxygen-oxygen pair-distribution functions from experimental high-precision x-ray diffraction data of bulk water by Skinner et al. [J. Chem. Phys. 141, 214507 (2014)] with particular focus on the intermediate range where small, but significant, correlations are found out to 17 Å. The second peak in the pair-distribution function at 4.5 Å is connected to tetrahedral coordination and was shown by Skinner et al. to change behavior with temperature below the temperature of minimum isothermal compressibility. Here we show that this is associated also with a peak growing at 11 Å which strongly indicates a collective character of fluctuations leading to the enhanced compressibility at lower temperatures. We note that the peak at ∼13.2 Å exhibits a temperature dependence similar to that of the density with a maximum close to 277 K or 4 °C. We analyze simulations of the TIP4P/2005 water model in the same manner and find excellent agreement between simulations and experiment albeit with a temperature shift of ∼20 K.

On the mechanism of muonium formation in liquid water

International Nuclear Information System (INIS)

Byakov, V.M.; Firsov, V.G.

1986-01-01

The experimental data on the influence of some solutes in water on formation probabilities of muonium, positronium and radiolytic hydrogen are compared. It is shown that the inhibiting action is very similar in all cases. This means that the formation mechanisms of muonium, positronium and radiolytic hydrogen have common features. Taking into account that the formation of radiolytic hydrogen and that of positronium proceeds via recombination mechanism with unsolvated electron as one of the precursors, it is asserted that the muonium formation mechanism is similar. (author)

L1188: A Promising Candidate for Cloud–Cloud Collisions Triggering the Formation of Low- and Intermediate-mass Stars

Energy Technology Data Exchange (ETDEWEB)

Gong, Yan; Fang, Min; Mao, Ruiqing; Zhang, Shaobo; Wang, Yuan; Su, Yang; Chen, Xuepeng; Yang, Ji; Wang, Hongchi; Lu, Dengrong, E-mail: ygong@pmo.ac.cn [Purple Mountain Observatory and Key Laboratory of Radio Astronomy, Chinese Academy of Sciences, 2 West Beijing Road, 210008 Nanjing (China)

2017-01-20

We present a new large-scale (2° × 2°) simultaneous {sup 12}CO, {sup 13}CO, and C{sup 18}O (J = 1–0) mapping of L1188 with the Purple Mountain Observatory 13.7 m telescope. Our observations have revealed that L1188 consists of two nearly orthogonal filamentary molecular clouds at two clearly separated velocities. Toward the intersection showing large velocity spreads, we find several bridging features connecting the two clouds in velocity, and an open arc structure that exhibits high excitation temperatures, enhanced {sup 12}CO and {sup 13}CO emission, and broad {sup 12}CO line wings. This agrees with the scenario that the two clouds are colliding with each other. The distribution of young stellar object (YSO) candidates implies an enhancement of star formation in the intersection of the two clouds. We suggest that a cloud–cloud collision happened in L1188 about 1 Myr ago, possibly triggering the formation of low- and intermediate-mass YSOs in the intersection.

A study on the formation of fouling in a heat exchanging system for Han-river water as cooling water

International Nuclear Information System (INIS)

Sung, Sun Kyung; Suh, Sang Ho; Rho, Hyung Woon; Cho, Young Il

2003-01-01

Scale is formed when hard water is heated or cooled in heat transfer equipments such as heat exchangers, condensers, evaporators, cooling towers, boilers, and pipe walls. When scale deposits in a heat exchanger surface, it is traditionally called fouling. The objective of the present study is to investigate the formation of fouling in a heat exchanging system. A lab-scale heat exchanging system is built-up to observe and measure the formation of fouling experimentally. Water analyses are conducted to obtain the properties of Han river water. In the present study a microscopic observation is conducted to visualize the process of scale formation. Hardness of Han-river water is higher than that of tap water in Seoul

Predicting hydrocarbon potential of an earth formation underlying a body of water

International Nuclear Information System (INIS)

Kaplan, I.R.; Demaison, G.J.

1983-01-01

A method for the on-site collection and examination of small concentrations of methane dissolved in water so as to predict hydrocarbon potential of an earth formation underlying a body of water, said formation being a source of said methane, comprises: (i) sampling the water; (ii) continuously vacuum separating said water into liquid and gas phases; (iii) quantitatively separating interfering gas species from methane; (iv) quantitatively oxidising said methane; (v) cryogenically trapping the resulting gaseous carbon dioxide and water vapor at a trapping station, and (vi) isotopically examining said trapped carbon dioxide and water vapour for carbon and deuterium distribution. (author)

Validation of OMA formation in cold brackish and sea waters

International Nuclear Information System (INIS)

Khelifa, A.; Hill, P.S.

2005-01-01

This study addressed the challenge of cleaning oil spilled in cold, ice-infested waters in the St. Lawrence estuary in the winter. The main objective was to develop an environmentally safe and efficient cleansing method. The use of an oil-mineral agglomeration (OMA) process has been proposed to improve dispersion and biodegradation of the spilled oil. This bench-scale study was conducted to validate this proposed remedial method. The theory for this natural attenuation process for oil spills on shores is that oil droplets and suspended sediments disperse in the water column and aggregate into OMAs. OMA formation involves floc break and aggregation by differential settling. This study examined the formation time and the concentration of OMA in a typical turbulent estuarine environment and determined the effect of sediment size and concentration on OMA formation. It also verified if OMA forms in cold brackish water considering 2 types of oils which are commonly transported along the St. Lawrence estuary to Quebec City. OMA formation was validated with Heidrun and IF30 crude oils and 2 types of engineered sediments to determine the best sediment to form OMA and to determine the minimum sediment concentration needed to maximize OMA formation. The minimum agitation time to reach this maximizing condition of OMA formation was also determined. It was concluded that OMAs form readily in cold brackish and seawater when Heidrun or IF30 crude oils are mixed with chalk or bentonite sediment. 23 refs., 2 tabs., 8 figs

WATER FORMATION IN THE UPPER ATMOSPHERE OF THE EARLY EARTH

Energy Technology Data Exchange (ETDEWEB)

Fleury, Benjamin; Carrasco, Nathalie; Marcq, Emmanuel; Vettier, Ludovic; Määttänen, Anni, E-mail: benjamin.fleury@latmos.ipsl.fr [Université Versailles St-Quentin, Sorbonne Universités, UPMC Univ. Paris 06, CNRS/INSU, LATMOS-IPSL, 11 Boulevard d’Alembert, F-78280 Guyancourt (France)

2015-07-10

The water concentration and distribution in the early Earth's atmosphere are important parameters that contribute to the chemistry and the radiative budget of the atmosphere. If the atmosphere above the troposphere is generally considered as dry, photochemistry is known to be responsible for the production of numerous minor species. Here we used an experimental setup to study the production of water in conditions simulating the chemistry above the troposphere of the early Earth with an atmospheric composition based on three major molecules: N{sub 2}, CO{sub 2}, and H{sub 2}. The formation of gaseous products was monitored using infrared spectroscopy. Water was found as the major product, with approximately 10% of the gas products detected. This important water formation is discussed in the context of the early Earth.

Air-sea fluxes and satellite-based estimation of water masses formation

Science.gov (United States)

Sabia, Roberto; Klockmann, Marlene; Fernandez-Prieto, Diego; Donlon, Craig

2015-04-01

Recent work linking satellite-based measurements of sea surface salinity (SSS) and sea surface temperature (SST) with traditional physical oceanography has demonstrated the capability of generating routinely satellite-derived surface T-S diagrams [1] and analyze the distribution/dynamics of SSS and its relative surface density with respect to in-situ measurements. Even more recently [2,3], this framework has been extended by exploiting these T-S diagrams as a diagnostic tool to derive water masses formation rates and areas. A water mass describes a water body with physical properties distinct from the surrounding water, formed at the ocean surface under specific conditions which determine its temperature and salinity. The SST and SSS (and thus also density) at the ocean surface are largely determined by fluxes of heat and freshwater. The surface density flux is a function of the latter two and describes the change of the density of seawater at the surface. To obtain observations of water mass formation is of great interest, since they serve as indirect observations of the thermo-haline circulation. The SSS data which has become available through the SMOS [4] and Aquarius [5] satellite missions will provide the possibility of studying also the effect of temporally-varying SSS fields on water mass formation. In the present study, the formation of water masses as a function of SST and SSS is derived from the surface density flux by integrating the latter over a specific area and time period in bins of SST and SSS and then taking the derivative of the total density flux with respect to density. This study presents a test case using SMOS SSS, OSTIA SST, as well as Argo ISAS SST and SSS for comparison, heat fluxes from the NOCS Surface Flux Data Set v2.0, OAFlux evaporation and CMORPH precipitation. The study area, initially referred to the North Atlantic, is extended over two additional ocean basins and the study period covers the 2011-2012 timeframe. Yearly, seasonal

Non-invasive detection of soil water content at intermediate field scale using natural neutrons from cosmic radiation

Energy Technology Data Exchange (ETDEWEB)

Oswald, Sascha; Rivera Villarreyes, Carlos; Baroni, Gabriele [Universitaet Potsdam, Institut fuer Erd und Umweltwissenschaften (Germany)

2011-07-01

The amount of water in the subsurface is a key factor influencing soil hydrology, run-off, evapotranspiration and plant development. A new measurement method is the so called cosmic ray method, recently introduced for soil moisture measurements by Zreda and coworkers. Secondary neutron fluxes, product of the interaction of primary cosmic-rays at the land surface, are strongly moderated by the presence of water in or above soil (soil moisture, snow and biomass water). Neutron counts at the ground/air interface represent a valuable observation at intermediate spatial scale which can be used to quantify stored water while distinguishing different water holding compartments at the land surface. We have performed such measurements in an agricultural field, in comparison with classical soil moisture measurement at a number of point locations. We discuss how to extract soil moisture values from the neutron counts, drawbacks of the method, but also that the results show a temporal development supported by the accompanying data.

Water rent: essence, sources of formation and accounting reflection

Directory of Open Access Journals (Sweden)

T.S. Osadcha

2016-06-01

Full Text Available There is the urgent necessity of the transition to a higher level of economic relations in the system of environmental management in the present conditions of economy of the country. As a result, the issues like formation of information support for water rent management, determining the ways of its calculation, distribution as well as usage of water rents require urgent solutions. The study focuses on the essence of water rent and forming organizational and methodological provisions of its accounting reflection to ensure sustainable ecological and economic development of the enterprise. As a result of research the classification of water rent, that affects reflection of such rent in accounting has been formed. It is established that the amount of water rent for accounting reflection can be defined as the difference between actual and normal profit of enterprise-water users. A number of analytical accounts of first and second order as well as the typical correspondence of accounts for accounting reflection of water rent have been suggested. The information from the Report on the formation of water rent that contains data on the sources of payback of expenses incurred for the maintenance of water bodies and the impact of ecological condition of water body on the size of water rent has been suggested to be used in order to manage the size of water rent and expenses incurred to obtain it. Thus, determining the amount of water rent will allow management personnel to adjust the activity of the company in accordance with the strategic objectives of the company’s development regarding the profitability and compliance with the concept of sustainable development.

Aspartate aminotransferase: the kinetic barriers facing the covalent intermediates on the reaction pathway

International Nuclear Information System (INIS)

Kirsch, J.F.; Julin, D.A.; McLeish, M.; Wiesinger, H.

1986-01-01

The intermediates, aldimine (A), quinonoid (Q) and ketimine (K), along the transaminase reaction coordinate were probed by isotope transfer and solvent exchange kinetics. Less than 0.003% of 3 H is transferred from C/sub α/[ 3 H]-aspartate to pyridoxamine phosphate in the cytoplasmic aspartate aminotransferase (cAATase) reaction implying either that Q does not exist as a kinetically competent intermediate or that there is a rapid exchange of isotope with solvent. The ratio of the rate constants for C/sub α/ hydrogen exchange vs keto acid product formation (k/sub exge//k/sub prod/) are 2.5 and 0.5 for the reactions of cAATase with C/sub α/ [ 2 H]-aspartate and mitochondrial (m) AATase with C/sub α/[ 2 H]-glutamate respectively. The latter reaction was also probed from the α-keto-glutarate side with carbonyl 0-18 enriched keto acid. This experiment gave k/sub exge//k/sub prod/ = 1.0 for oxygen-18 exchange in α-ketoglutarate versus amino acid formation. The two exchange experiments with mAATase are interpreted in terms of a model in which the rate constant for diffusion of water from the active site is comparable with those for product forming steps

Chemically activated formation of organic acids in reactions of the Criegee intermediate with aldehydes and ketones.

Science.gov (United States)

Jalan, Amrit; Allen, Joshua W; Green, William H

2013-10-21

Reactions of the Criegee intermediate (CI, ˙CH2OO˙) are important in atmospheric ozonolysis models. In this work, we compute the rates for reactions between ˙CH2OO˙ and HCHO, CH3CHO and CH3COCH3 leading to the formation of secondary ozonides (SOZ) and organic acids. Relative to infinitely separated reactants, the SOZ in all three cases is found to be 48-51 kcal mol(-1) lower in energy, formed via 1,3-cycloaddition of ˙CH2OO˙ across the C=O bond. The lowest energy pathway found for SOZ decomposition is intramolecular disproportionation of the singlet biradical intermediate formed from cleavage of the O-O bond to form hydroxyalkyl esters. These hydroxyalkyl esters undergo concerted decomposition providing a low energy pathway from SOZ to acids. Geometries and frequencies of all stationary points were obtained using the B3LYP/MG3S DFT model chemistry, and energies were refined using RCCSD(T)-F12a/cc-pVTZ-F12 single-point calculations. RRKM calculations were used to obtain microcanonical rate coefficients (k(E)) and the reservoir state method was used to obtain temperature and pressure dependent rate coefficients (k(T, P)) and product branching ratios. At atmospheric pressure, the yield of collisionally stabilized SOZ was found to increase in the order HCHO reactions were found to be the most sensitive parameters determining SOZ and organic acid yield.

Detection, formation and occurrence of 13 new polar phenolic chlorinated and brominated disinfection byproducts in drinking water.

Science.gov (United States)

Pan, Yang; Wang, Ying; Li, Aimin; Xu, Bin; Xian, Qiming; Shuang, Chendong; Shi, Peng; Zhou, Qing

2017-04-01

Recently, 13 new polar phenolic chlorinated and brominated disinfection byproducts (Cl- and Br-DBPs) were identified and quantified in simulated chlorinated drinking water by adopting product ion scan, precursor ion scan, and multiple reaction monitoring (MRM) analyses using ultra performance liquid chromatography/electrospray ionization-triple quadrupole mass spectrometry (UPLC/ESI-tqMS). The 13 new DBPs have been drawing increasing concern not only because they possess significantly higher growth inhibition, developmental toxicity, and chronic cytotoxicity than commonly known aliphatic DBPs, but also because they act as intermediate DBPs that can decompose to form the U.S. EPA regulated DBPs. In this study, through MS parameter optimization of the UPLC/ESI-tqMS MRM analysis, the instrument detection and quantitation limits of the 13 new DBPs were substantially lowered to 0.42-6.44 and 1.35-16.51 μg/L, respectively. The total levels of the 13 new DBPs formed in chlorination were much higher than those formed in chloramination within a contact time of 3 d. In chlorination, the 13 new DBPs formed quickly and decomposed rapidly, and their total concentration kept on decreasing with contact time. In chloramination, the levels of the dominant species (i.e., trihalo-phenols) firstly increased and then decreased with contact time, whereas the levels of the other new DBPs were relatively low and kept on increasing with contact time. An increasing of pH from 6.0 to 9.0 decreased the formation of the 13 new DBPs by 57.8% and 62.3% in chlorination and chloramination, respectively. Gallic acid was found to be present in various simulated and real source water samples and was demonstrated to be a precursor of the 13 new DBPs with elucidated formation pathways. Furthermore, 12 of the 13 new DBPs were detected in 16 tap water samples obtained from major cities in East China, at total levels from 9.5 to 329.8 ng/L. The concentrations of the new DBPs were higher in samples

Evidence of preorganization in quinonoid intermediate formation from L-Trp in H463F mutant Escherichia coli tryptophan indole-lyase from effects of pressure and pH.

Science.gov (United States)

Phillips, Robert S; Kalu, Ukoha; Hay, Sam

2012-08-21

The effects of pH and hydrostatic pressure on the reaction of H463F tryptophan indole-lyase (TIL) have been evaluated. The mutant TIL shows very low activity for elimination of indole but is still competent to form a quinonoid intermediate from l-tryptophan [Phillips, R. S., Johnson, N., and Kamath, A. V. (2002) Biochemistry 41, 4012-4019]. Stopped-flow measurements show that the formation of the quinonoid intermediate at 505 nm is affected by pH, with a bell-shaped dependence for the forward rate constant, k(f), and dependence on a single basic group for the reverse rate constant, k(r), with the following values: pK(a1) = 8.14 ± 0.15, pK(a2) = 7.54 ± 0.15, k(f,min) = 18.1 ± 1.3 s(-1), k(f,max) = 179 ± 46.3 s(-1), k(r,min) = 11.4 ± 1.2 s(-1), and k(r,max) = 33 ± 1.6 s(-1). The pH effects may be due to ionization of Tyr74 as the base and Cys298 as the acid influencing the rate constant for deprotonation. High-pressure stopped-flow measurements were performed at pH 8, which is the optimum for the forward reaction. The rate constants show an increase with pressure up to 100 MPa and a subsequent decrease above 100 MPa. Fitting the pressure data gives the following values: k(f,0) = 15.4 ± 0.8 s(-1), ΔV(‡) = -29.4 ± 2.9 cm(3) mol(-1), and Δβ(‡) = -0.23 ± 0.03 cm(3) mol(-1) MPa(-1) for the forward reaction, and k(r,0) = 20.7 ± 0.8 s(-1), ΔV(‡) = -9.6 ± 2.3 cm(3) mol(-1), and Δβ(‡) = -0.05 ± 0.02 cm(3) mol(-1) MPa(-1) for the reverse reaction. The primary kinetic isotope effect on quinonoid intermediate formation at pH 8 is small (~2) and is not significantly pressure-dependent, suggesting that the effect of pressure on k(f) may be due to perturbation of an active site preorganization step. The negative activation volume is also consistent with preorganization of the ES complex prior to quinonoid intermediate formation, and the negative compressibility may be due to the effect of pressure on the enzyme conformation. These results support the

Transport description of intermediate processes in heavy ion collisions

International Nuclear Information System (INIS)

Ayik, S.; Shivakumar, B.; Shapira, D.

1986-01-01

An extension of the diffusion model is proposed in order to describe the intermediate processes and the compound nucleus formation in heavy ion collisions. The model describes the intermediate processes and fusion in terms of the formation and the evolution of a long-lived dinuclear molecular complex (DMC) and its subsequent decay by fragmentation. The colliding ions can be trapped into the pocket of the entrance channel nucleus-nucleus potential and a DMC is formed. This DMC acts as a doorway state towards formation of a completely equilibrated compound nucleus (CN). It evolves through the exchange of nucleons to different dinuclear configurations. At each stage of its evolution, there is a finite probability for direct fragmentation into outgoing channels by thermal penetration over the barrier. The doorway states that do not fragment relax into a CN configuration and are identified as the fusion yield. 8 refs

The formation of hydrogen in the radiolysis of water in closed volumes

International Nuclear Information System (INIS)

Kabakchi, S.A.; Lebedeva, I.E.

1984-01-01

By applying the sum total of the elementary reactions involving short-lived particles it is possible to fairly accurately calculate the kinetics of hydrogen formation and of its separation from water, and also to calculate the accumulation of hydrogen peroxide and oxygen during radiolysis of pure water and water solutions at room temperature. This paper describes a semi-empirical method to calculate the kinetics of hydrogen formation for certain cases encountered in nuclear power production. (author)

A new chlorine logging tool: Application in the oilfield development with high salinity formation water

International Nuclear Information System (INIS)

Qing-Yuan, He; Xin-Miao, Hu; Geng-Fei, Wu; Wen-DA, J.

1997-01-01

Radiating formations with isotopes neutron source (Am-Be), and using chlorine element contained in the formation water as a tracer indicator, the chlorine spectrum well logging tool has been regarded as the important and useful tool in the determination of water flooding intensity of formation intervals, especially in the oilfield development stages with high salinity formation water. However, the accuracy of determination of the oil/water-bearings needs to be improved. A new chlorine spectrum logging tool with two detectors has been developed. The short (near) detector uses a He-3 counter tube to measure formation epithermal neutron intensity, the long (far) detector uses a BGO crystal detector to replace traditional Nal detector for measuring the captured X gamma ray spectrum produced by the thermal neutron capture process in the formation. Although the energy resolution of BGO detector to gamma rays is less effective than that of Nal detector, the efficiency of BGO detector to high energy gamma rays is much better. This advantage helps to detect captured chlorine gamma rays, which increases the ability of chlorine element detection. The effect of statistical errors is also reduced. The spectrum autostabilization function in the downhole tool improves the reliability of the whole system. The new chlorine spectrum logging tool can give three log curves simultaneously, these curves are formation porosity, chlorine content, and the ratio of chlorine content and thermal neutron intensity. When formation porosity is larger than 10 p.u, formation water salinity is greater than 40,000 ppm, the resolution to the oil/water-bearings is increased to about 10% compared with the old version tool. Field tests show that the accuracy of water flooding intensity evaluation has been upgraded considerably with the use of new chlorine spectrum logging tool, which contributes greatly to the oilfield development with high salinity formation water

A new chlorine logging tool: Application in the oilfield development with high salinity formation water

Energy Technology Data Exchange (ETDEWEB)

Qing-Yuan, He; Xin-Miao, Hu; Geng-Fei, Wu [China National Petroleum Corp. (China). Jianghan Well Logging Institute; Wen-DA, J. [China National Petroleum Corp. (China). Development Bureau

1997-10-01

Radiating formations with isotopes neutron source (Am-Be), and using chlorine element contained in the formation water as a tracer indicator, the chlorine spectrum well logging tool has been regarded as the important and useful tool in the determination of water flooding intensity of formation intervals, especially in the oilfield development stages with high salinity formation water. However, the accuracy of determination of the oil/water-bearings needs to be improved. A new chlorine spectrum logging tool with two detectors has been developed. The short (near) detector uses a He-3 counter tube to measure formation epithermal neutron intensity, the long (far) detector uses a BGO crystal detector to replace traditional Nal detector for measuring the captured X gamma ray spectrum produced by the thermal neutron capture process in the formation. Although the energy resolution of BGO detector to gamma rays is less effective than that of Nal detector, the efficiency of BGO detector to high energy gamma rays is much better. This advantage helps to detect captured chlorine gamma rays, which increases the ability of chlorine element detection. The effect of statistical errors is also reduced. The spectrum autostabilization function in the downhole tool improves the reliability of the whole system. The new chlorine spectrum logging tool can give three log curves simultaneously, these curves are formation porosity, chlorine content, and the ratio of chlorine content and thermal neutron intensity. When formation porosity is larger than 10 p.u, formation water salinity is greater than 40,000 ppm, the resolution to the oil/water-bearings is increased to about 10% compared with the old version tool. Field tests show that the accuracy of water flooding intensity evaluation has been upgraded considerably with the use of new chlorine spectrum logging tool, which contributes greatly to the oilfield development with high salinity formation water 4 refs., 2 tabs., 7 figs.

Enhanced formation of disinfection byproducts in shale gas wastewater-impacted drinking water supplies.

Science.gov (United States)

Parker, Kimberly M; Zeng, Teng; Harkness, Jennifer; Vengosh, Avner; Mitch, William A

2014-10-07

The disposal and leaks of hydraulic fracturing wastewater (HFW) to the environment pose human health risks. Since HFW is typically characterized by elevated salinity, concerns have been raised whether the high bromide and iodide in HFW may promote the formation of disinfection byproducts (DBPs) and alter their speciation to more toxic brominated and iodinated analogues. This study evaluated the minimum volume percentage of two Marcellus Shale and one Fayetteville Shale HFWs diluted by fresh water collected from the Ohio and Allegheny Rivers that would generate and/or alter the formation and speciation of DBPs following chlorination, chloramination, and ozonation treatments of the blended solutions. During chlorination, dilutions as low as 0.01% HFW altered the speciation toward formation of brominated and iodinated trihalomethanes (THMs) and brominated haloacetonitriles (HANs), and dilutions as low as 0.03% increased the overall formation of both compound classes. The increase in bromide concentration associated with 0.01-0.03% contribution of Marcellus HFW (a range of 70-200 μg/L for HFW with bromide = 600 mg/L) mimics the increased bromide levels observed in western Pennsylvanian surface waters following the Marcellus Shale gas production boom. Chloramination reduced HAN and regulated THM formation; however, iodinated trihalomethane formation was observed at lower pH. For municipal wastewater-impacted river water, the presence of 0.1% HFW increased the formation of N-nitrosodimethylamine (NDMA) during chloramination, particularly for the high iodide (54 ppm) Fayetteville Shale HFW. Finally, ozonation of 0.01-0.03% HFW-impacted river water resulted in significant increases in bromate formation. The results suggest that total elimination of HFW discharge and/or installation of halide-specific removal techniques in centralized brine treatment facilities may be a better strategy to mitigate impacts on downstream drinking water treatment plants than altering

Tritium formation and elimination in light-water reactors

International Nuclear Information System (INIS)

Dolle, L.; Briec, M.; Miquel, P.

1976-01-01

Light-water reactors have a tritium balance which should be considered from both the working constraint and environmental pollution aspects. The formation of tritium in the primary circuit and in the fuel, the elimination and enrichment processes are considered [fr

Removal of Intermediate Aromatic Halogenated DBPs by Activated Carbon Adsorption: A New Approach to Controlling Halogenated DBPs in Chlorinated Drinking Water.

Science.gov (United States)

Jiang, Jingyi; Zhang, Xiangru; Zhu, Xiaohu; Li, Yu

2017-03-21

During chlorine disinfection of drinking water, chlorine may react with natural organic matter (NOM) and bromide ion in raw water to generate halogenated disinfection byproducts (DBPs). To mitigate adverse effects from DBP exposure, granular activated carbon (GAC) adsorption has been considered as one of the best available technologies for removing NOM (DBP precursor) in drinking water treatment. Recently, we have found that many aromatic halogenated DBPs form in chlorination, and they act as intermediate DBPs to decompose and form commonly known DBPs including trihalomethanes and haloacetic acids. In this work, we proposed a new approach to controlling drinking water halogenated DBPs by GAC adsorption of intermediate aromatic halogenated DBPs during chlorination, rather than by GAC adsorption of NOM prior to chlorination (i.e., traditional approach). Rapid small-scale column tests were used to simulate GAC adsorption in the new and traditional approaches. Significant reductions of aromatic halogenated DBPs were observed in the effluents with the new approach; the removals of total organic halogen, trihalomethanes, and haloacetic acids by the new approach always exceeded those by the traditional approach; and the effluents with the new approach were considerably less developmentally toxic than those with the traditional approach. Our findings indicate that the new approach is substantially more effective in controlling halogenated DBPs than the traditional approach.

Nitric oxide formation from the reaction of nitrite with carp and rabbit hemoglobin at intermediate oxygen saturations

DEFF Research Database (Denmark)

Jensen, Frank Bo

2008-01-01

The nitrite reductase activity of deoxyhemoglobin has received much recent interest because the nitric oxide produced in this reaction may participate in blood flow regulation during hypoxia. The present study used spectral deconvolution to characterize the reaction of nitrite with carp and rabbit...... hemoglobin at different constant oxygen tensions that generate the full range of physiological relevant oxygen saturations. Carp is a hypoxia-tolerant species with very high hemoglobin oxygen affinity, and the high R-state character and low redox potential of the hemoglobin is hypothesized to promote...... NO generation from nitrite. The reaction of nitrite with deoxyhemoglobin leads to a 1 : 1 formation of nitrosylhemoglobin and methemoglobin in both species. At intermediate oxygen saturations, the reaction with deoxyhemoglobin is clearly favored over that with oxyhemoglobin, and the oxyhemoglobin reaction...

The deterioration of intermediate moisture foods

Science.gov (United States)

Labruza, T. P.

1971-01-01

Deteriorative reactions are low and food quality high if intermediate moisture content of a food is held at a water activity of 0.6 to 0.75. Information is of interest to food processing and packaging industry.

Influence of RANEY Nickel on the Formation of Intermediates in the Degradation of Lignin

Directory of Open Access Journals (Sweden)

Daniel Forchheim

2012-01-01

Full Text Available Lignin forms an important part of lignocellulosic biomass and is an abundantly available residue. It is a potential renewable source of phenol. Liquefaction of enzymatic hydrolysis lignin as well as catalytical hydrodeoxygenation of the main intermediates in the degradation of lignin, that is, catechol and guaiacol, was studied. The cleavage of the ether bonds, which are abundant in the molecular structure of lignin, can be realised in near-critical water (573 to 673 K, 20 to 30 MPa. Hydrothermal treatment in this context provides high selectivity in respect to hydroxybenzenes, especially catechol. RANEY Nickel was found to be an adequate catalyst for hydrodeoxygenation. Although it does not influence the cleavage of ether bonds, RANEY Nickel favours the production of phenol from both lignin and catechol. The main product from hydrodeoxygenation of guaiacol with RANEY Nickel was cyclohexanol. Reaction mechanism and kinetics of the degradation of guaiacol were explored.

Stable isotope fractionation during bacterial sulfate reduction is controlled by reoxidation of intermediates

Science.gov (United States)

Mangalo, Muna; Meckenstock, Rainer U.; Stichler, Willibald; Einsiedl, Florian

2007-09-01

Bacterial sulfate reduction is one of the most important respiration processes in anoxic habitats and is often assessed by analyzing the results of stable isotope fractionation. However, stable isotope fractionation is supposed to be influenced by the reduction rate and other parameters, such as temperature. We studied here the mechanistic basics of observed differences in stable isotope fractionation during bacterial sulfate reduction. Batch experiments with four sulfate-reducing strains ( Desulfovibrio desulfuricans, Desulfobacca acetoxidans, Desulfonatronovibrio hydrogenovorans, and strain TRM1) were performed. These microorganisms metabolize different carbon sources (lactate, acetate, formate, and toluene) and showed broad variations in their sulfur isotope enrichment factors. We performed a series of experiments on isotope exchange of 18O between residual sulfate and ambient water. Batch experiments were conducted with 18O-enriched (δ 18O water = +700‰) and depleted water (δ 18O water = -40‰), respectively, and the stable 18O isotope shift in the residual sulfate was followed. For Desulfovibrio desulfuricans and Desulfonatronovibrio hydrogenovorans, which are both characterized by low sulfur isotope fractionation ( ɛS > -13.2‰), δ 18O values in the remaining sulfate increased by only 50‰ during growth when 18O-enriched water was used for the growth medium. In contrast, with Desulfobacca acetoxidans and strain TRM1 ( ɛS factor ( ɛS exchange with water during sulfate reduction. However, this neither takes place in the sulfate itself nor during formation of APS (adenosine-5'-phosphosulfate), but rather in intermediates of the sulfate reduction pathway. These may in turn be partially reoxidized to form sulfate. This reoxidation leads to an incorporation of oxygen from water into the "recycled" sulfate changing the overall 18O isotopic composition of the remaining sulfate fraction. Our study shows that such incorporation of 18O is correlated with the

Modelling of Disinfection by-products formation via UV irradiation of the water from Tajan River (source water for Sari drinking water, Iran

Directory of Open Access Journals (Sweden)

Allahbakhsh Javid

2013-11-01

Full Text Available Background & Aims of the Study Irradiation with ultraviolet light (UV is used for the disinfection of bacterial contaminants in the production of potable water. The main objective of the study was to investigate and model Disinfection By-Products (DBPs formation due to the UV Irradiation of the Tajan River water under different Irradiation conditions. Materials & Methods:  Water samples were collected throughout September 2011 to August 2013. Transportation of the sample to the laboratory was done on ice in a cooler, and physiochemical analysis was conducted immediately within one day. Dissolved organic carbon (DOC was determined by a TOC analyzer. Irradiation experiments were conducted in a series of 25 mL glass serum bottles with Teflon septa. The present study adopts an orthogonal design. The design involved irradiation with UV at a UV/DOC ratio of 0.5–3.0 and incubating (headspace-free storage for 5–25 sec. A 1 mM phosphate buffer maintained the pH at 6, 7, or 8 respectively, and an incubator maintained the temperature (Temp at 15, 20, or 25 °C respectively. The development of empirical models for DBPs formation used a multivariate regression procedure (stepwise which applied the SPSS System for Windows (Version 16.0. Results:  The results showed that the total DBPs formation ranged between 12.3 and 67.4 mg/l and that control of the levels was primarily due to the reaction time and the dissolved organic carbon level (DOC in the water. Conclusions:  Reaction time and level of DOC concentrations in water exerted a dominant influence on the formation of DBPs during the UV irradiation of water from the Tajan River. The relationships between the measured and predicted values were satisfactory with R 2 values ranging from 0.89 (for Octanal–0.92 (for Formaldehydes. The DOC level in water is the key factor in controlling DBPs formation.

Models for predicting disinfection byproduct (DBP) formation in drinking waters: a chronological review.

Science.gov (United States)

Chowdhury, Shakhawat; Champagne, Pascale; McLellan, P James

2009-07-01

Disinfection for the supply of safe drinking water forms a variety of known and unknown byproducts through reactions between the disinfectants and natural organic matter. Chronic exposure to disinfection byproducts through the ingestion of drinking water, inhalation and dermal contact during regular indoor activities (e.g., showering, bathing, cooking) may pose cancer and non-cancer risks to human health. Since their discovery in drinking water in 1974, numerous studies have presented models to predict DBP formation in drinking water. To date, more than 48 scientific publications have reported 118 models to predict DBP formation in drinking waters. These models were developed through laboratory and field-scale experiments using raw, pretreated and synthetic waters. This paper aims to review DBP predictive models, analyze the model variables, assess the model advantages and limitations, and to determine their applicability to different water supply systems. The paper identifies the current challenges and future research needs to better control DBP formation. Finally, important directions for future research are recommended to protect human health and to follow the best management practices.

Early-type galaxies at intermediate redshift observed with Hubble space telescope WFC3: perspectives on recent star formation

Energy Technology Data Exchange (ETDEWEB)

Rutkowski, Michael J. [Minnesota Institute for Astrophysics, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States); Jeong, Hyunjin; Yi, Sukyoung K. [Department of Astronomy, Yonsei University 134, Shinchon-dong, Sudaemun-gu, Seoul 120-179 (Korea, Republic of); Cohen, Seth H.; Windhorst, Rogier A. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287-1404 (United States); Kaviraj, Sugata [Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB (United Kingdom); Ryan, Russell E. Jr.; Koekemoer, Anton [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Hathi, Nimish P. [Aix Marseille Université, CNRS, LAM, UMR 7326, F-13388, Marseille (France); Dopita, Michael A. [Research School of Physics and Astronomy, The Australian National University, Canberra, ACT 2611 (Australia)

2014-12-01

We present an analysis of the stellar populations of 102 visually selected early-type galaxies (ETGs) with spectroscopic redshifts (0.35 ≲ z ≲ 1.5) from observations in the Early Release Science program with the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST). We fit one- and two-component synthetic stellar models to the ETGs UV-optical-near-IR spectral energy distributions and find that a large fraction (∼40%) are likely to have experienced a minor (f{sub YC} ≲ 10% of stellar mass) burst of recent (t{sub YC} ≲ 1 Gyr) star formation. The measured age and mass fraction of the young stellar populations do not strongly trend with measurements of galaxy morphology. We note that massive (M > 10{sup 10.5} M {sub ☉}) recent star-forming ETGs appear to have larger sizes. Furthermore, high-mass, quiescent ETGs identified with likely companions populate a distinct region in the size-mass parameter space, in comparison with the distribution of massive ETGs with evidence of recent star formation (RSF). We conclude that both mechanisms of quenching star formation in disk-like ETGs and (gas-rich, minor) merger activity contribute to the formation of young stars and the size-mass evolution of intermediate redshift ETGs. The number of ETGs for which we have both HST WFC3 panchromatic (especially UV) imaging and spectroscopically confirmed redshifts is relatively small, therefore, a conclusion about the relative roles of both of these mechanisms remains an open question.

Characterization of intermediate products of solar photocatalytic degradation of ranitidine at pilot-scale.

Science.gov (United States)

Radjenović, Jelena; Sirtori, Carla; Petrović, Mira; Barceló, Damià; Malato, Sixto

2010-04-01

In the present study the mechanisms of solar photodegradation of H(2)-receptor antagonist ranitidine (RNTD) were studied in a well-defined system of a pilot plant scale Compound Parabolic Collector (CPC) reactor. Two types of heterogeneous photocatalytic experiments were performed: catalysed by titanium-dioxide (TiO(2)) semiconductor and by Fenton reagent (Fe(2+)/H(2)O(2)), each one with distilled water and synthetic wastewater effluent matrix. Complete disappearance of the parent compounds and discreet mineralization were attained in all experiments. Furthermore, kinetic parameters, main intermediate products, release of heteroatoms and formation of carboxylic acids are discussed. The main intermediate products of photocatalytic degradation of RNTD have been structurally elucidated by tandem mass spectrometry (MS(2)) experiments performed at quadrupole-time of flight (QqToF) mass analyzer coupled to ultra-performance liquid chromatograph (UPLC). RNTD displayed high reactivity towards OH radicals, although a product of conduction band electrons reduction was also present in the experiment with TiO(2). In the absence of standards, quantification of intermediates was not possible and only qualitative profiles of their evolution could be determined. The proposed TiO(2) and photo-Fenton degradation routes of RNTD are reported for the first time. (c) 2010 Elsevier Ltd. All rights reserved.

Intermediate-Mass Black Holes

Science.gov (United States)

Miller, M. Coleman; Colbert, E. J. M.

2004-01-01

The mathematical simplicity of black holes, combined with their links to some of the most energetic events in the universe, means that black holes are key objects for fundamental physics and astrophysics. Until recently, it was generally believed that black holes in nature appear in two broad mass ranges: stellar-mass (M~3 20 M⊙), which are produced by the core collapse of massive stars, and supermassive (M~106 1010 M⊙), which are found in the centers of galaxies and are produced by a still uncertain combination of processes. In the last few years, however, evidence has accumulated for an intermediate-mass class of black holes, with M~102 104 M⊙. If such objects exist they have important implications for the dynamics of stellar clusters, the formation of supermassive black holes, and the production and detection of gravitational waves. We review the evidence for intermediate-mass black holes and discuss future observational and theoretical work that will help clarify numerous outstanding questions about these objects.

Formation, precursors, control, and occurrence of nitrosamines in drinking water: a review.

Science.gov (United States)

Krasner, Stuart W; Mitch, William A; McCurry, Daniel L; Hanigan, David; Westerhoff, Paul

2013-09-01

This review summarizes major findings over the last decade related to nitrosamines in drinking water, with a particular focus on N-nitrosodimethylamine (NDMA), because it is among the most widely detected nitrosamines in drinking waters. The reaction of inorganic dichloramine with amine precursors is likely the dominant mechanism responsible for NDMA formation in drinking waters. Even when occurrence surveys found NDMA formation in chlorinated drinking waters, it is unclear whether chloramination resulted from ammonia in the source waters. NDMA formation has been associated with the use of quaternary amine-based coagulants and anion exchange resins, and wastewater-impaired source waters. Specific NDMA precursors in wastewater-impacted source waters may include tertiary amine-containing pharmaceuticals or other quaternary amine-containing constituents of personal care products. Options for nitrosamine control include physical removal of precursors by activated carbon or precursor deactivation by application of oxidants, particularly ozone or chlorine, upstream of chloramination. Although NDMA has been the most prevalent nitrosamine detected in worldwide occurrence surveys, it may account for only ≈ 5% of all nitrosamines in chloraminated drinking waters. Other significant contributors to total nitrosamines are poorly characterized. However, high levels of certain low molecular weight nitrosamines have been detected in certain Chinese waters suspected to be impaired by industrial effluents. The review concludes by identifying research needs that should be addressed over the next decade. Copyright © 2013 Elsevier Ltd. All rights reserved.

A new generation of models for water-in-oil emulsion formation

International Nuclear Information System (INIS)

Fingas, M.

2009-01-01

Water-in-oil emulsions form after oil or petroleum products are spilled, and can make the cleanup of oil spills difficult. This paper discussed new modelling schemes designed for the formation of water-in-oil emulsions. Density, viscosity, asphaltene and resin contents were used to compute a class index for unstable, entrained water-in-oil states, meso-stable, or stable emulsions. Prediction schemes were used to estimate the water content and viscosity of the water-in-oil states and the time to formation with wave height inputs. A numerical values was used for each type of water-in-oil type. The properties of the starting oil were correlated with the numerical scheme. New regressions were then performed using a Gaussian-style regression expansion technique. Data obtained from the models suggested that water-in-oil types are stabilized by both asphaltenes and resins. The optimized model was then compared with earlier models. The study showed that the new model has the capacity to accurately predict oil-in-water types approximately 90 per cent of the time using only resin, saturate, asphaltene, viscosity, and density data. 17 refs., 8 tabs., 8 figs

Elasticity and physico-chemical properties during drinking water biofilm formation.

Science.gov (United States)

Abe, Yumiko; Polyakov, Pavel; Skali-Lami, Salaheddine; Francius, Grégory

2011-08-01

Atomic force microscope techniques and multi-staining fluorescence microscopy were employed to study the steps in drinking water biofilm formation. During the formation of a conditioning layer, surface hydrophobic forces increased and the range of characteristic hydrophobic forces diversified with time, becoming progressively complex in macromolecular composition, which in return triggered irreversible cellular adhesion. AFM visualization of 1 to 8 week drinking water biofilms showed a spatially discontinuous and heterogeneous distribution comprising an extensive network of filamentous fungi in which biofilm aggregates were embedded. The elastic modulus of 40-day-old biofilms ranged from 200 to 9000 kPa, and the biofilm deposits with a height >0.5 μm had an elastic modulus water biofilms were composed of a soft top layer and a basal layer with significantly higher elastic modulus values falling in the range of fungal elasticity.

Potential of select intermediate-volatility organic compounds and consumer products for secondary organic aerosol and ozone formation under relevant urban conditions

Science.gov (United States)

Li, Weihua; Li, Lijie; Chen, Chia-li; Kacarab, Mary; Peng, Weihan; Price, Derek; Xu, Jin; Cocker, David R.

2018-04-01

Emissions of certain low vapor pressure-volatile organic compounds (LVP-VOCs) are considered exempt to volatile organic compounds (VOC) regulations due to their low evaporation rates. However, these compounds may still play a role in ambient secondary organic aerosol (SOA) and ozone formation. The LVP-VOCs selected for this work are categorized as intermediate-volatility organic compounds (IVOCs) according to their vapor pressures and molecular formulas. In this study, the evaporation rates of 14 select IVOCs are investigated with half of them losing more than 95% of their mass in less than one month. Further, SOA and ozone formation are presented from 11 select IVOCs and 5 IVOC-containing generic consumer products under atmospherically relevant conditions using varying radical sources (NOx and/or H2O2) and a surrogate reactive organic gas (ROG) mixture. Benzyl alcohol (0.41), n-heptadecane (0.38), and diethylene glycol monobutyl ether (0.16) are determined to have SOA yields greater than 0.1 in the presence of NOx and a surrogate urban hydrocarbon mixture. IVOCs also influence ozone formation from the surrogate urban mixture by impacting radical levels and NOx availability. The addition of lab created generic consumer products has a weak influence on ozone formation from the surrogate mixture but strongly affects SOA formation. The overall SOA and ozone formation of the generic consumer products could not be explained solely by the results of the pure IVOC experiments.

The MHD intermediate shock interaction with an intermediate wave: Are intermediate shocks physical?

International Nuclear Information System (INIS)

Wu, C.C.

1988-01-01

Contrary to the usual belief that MHD intermediate shocks are extraneous, the authors have recently shown by numerical solutions of dissipative MHD equations that intermediate shocks are admissible and can be formed through nonlinear steepening from a continuous wave. In this paper, he clarifies the differences between the conventional view and the results by studying the interaction of an MHD intermediate shock with an intermediate wave. The study reaffirms his results. In addition, the study shows that there exists a larger class of shocklike solutions in the time-dependent dissiaptive MHD equations than are given by the MHD Rankine-Hugoniot relations. it also suggests a mechanism for forming rotational discontinuities through the interaction of an intermediate shock with an intermediate wave. The results are of importance not only to the MHD shock theory but also to studies such as magnetic field reconnection models

Formation of gas bubbles in gas superheated water

International Nuclear Information System (INIS)

Finkelstein, Y.

1984-05-01

The phenomenon of bubbles formation in supersaturated solutions of gases in water is a transport process, the final result of which is a separation of phases. In spite of its widespread appearance in industry and in nature, no model exists that can explain it and predict the degree of supersaturation which a gas-water solution can tolerate before bubbles are formed. The objective of this study was to fill this gap, and indeed, an extensive experimental work was carried out, a model was established and simple but accurate means were developed for predicting the tolerable degree of supersaturation of gas-water solutions. The model is also capable of predicting quite accurately the activation phenomenon in water. Superheating and supercooling phenomena were also examined in the light of the new model. (author)

Secondary formation of disinfection by-products by UV treatment of swimming pool water

Energy Technology Data Exchange (ETDEWEB)

Spiliotopoulou, Aikaterini [Water ApS, Farum Gydevej 64, 3520 Farum (Denmark); Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 113, 2800 Kongens Lyngby (Denmark); Hansen, Kamilla M.S., E-mail: kmsh@env.dtu.dk [Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 113, 2800 Kongens Lyngby (Denmark); Andersen, Henrik R. [Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 113, 2800 Kongens Lyngby (Denmark)

2015-07-01

Formation of disinfection by-products (DBPs) during experimental UV treatment of pool water has previously been reported with little concurrence between laboratory studies, field studies and research groups. In the current study, changes in concentration of seven out of eleven investigated volatile DBPs were observed in experiments using medium pressure UV treatment, with and without chlorine and after post-UV chlorination. Results showed that post-UV chlorine consumption increased, dose-dependently, with UV treatment dose. A clear absence of trihalomethane formation by UV and UV with chlorine was observed, while small yet statistically significant increases in dichloroacetonitrile and dichloropropanone concentrations were detected. Results indicate that post-UV chlorination clearly induced secondary formation of several DBPs. However, the formation of total trihalomethanes was no greater than what could be replicated by performing the DBP formation assay with higher chlorine concentrations to simulate extended chlorination. Post-UV chlorination of water from a swimming pool that continuously uses UV treatment to control combined chlorine could not induce secondary formation for most DBPs. Concurrence for induction of trihalomethanes was identified between post-UV chlorination treatments and simulated extended chlorination time treatment. Trihalomethanes could not be induced by UV treatment of water from a continuously UV treated pool. This indicates that literature reports of experimentally induced trihalomethane formation by UV may be a result of kinetic increase in formation by UV. However, this does not imply that higher trihalomethane concentrations would occur in pools that apply continuous UV treatment. The bromine fraction of halogens in formed trihalomethanes increased with UV dose. This indicates that UV removes bromine atoms from larger molecules that participate in trihalomethane production during post-UV chlorination. Additionally, no significant

Secondary formation of disinfection by-products by UV treatment of swimming pool water

International Nuclear Information System (INIS)

Spiliotopoulou, Aikaterini; Hansen, Kamilla M.S.; Andersen, Henrik R.

2015-01-01

Formation of disinfection by-products (DBPs) during experimental UV treatment of pool water has previously been reported with little concurrence between laboratory studies, field studies and research groups. In the current study, changes in concentration of seven out of eleven investigated volatile DBPs were observed in experiments using medium pressure UV treatment, with and without chlorine and after post-UV chlorination. Results showed that post-UV chlorine consumption increased, dose-dependently, with UV treatment dose. A clear absence of trihalomethane formation by UV and UV with chlorine was observed, while small yet statistically significant increases in dichloroacetonitrile and dichloropropanone concentrations were detected. Results indicate that post-UV chlorination clearly induced secondary formation of several DBPs. However, the formation of total trihalomethanes was no greater than what could be replicated by performing the DBP formation assay with higher chlorine concentrations to simulate extended chlorination. Post-UV chlorination of water from a swimming pool that continuously uses UV treatment to control combined chlorine could not induce secondary formation for most DBPs. Concurrence for induction of trihalomethanes was identified between post-UV chlorination treatments and simulated extended chlorination time treatment. Trihalomethanes could not be induced by UV treatment of water from a continuously UV treated pool. This indicates that literature reports of experimentally induced trihalomethane formation by UV may be a result of kinetic increase in formation by UV. However, this does not imply that higher trihalomethane concentrations would occur in pools that apply continuous UV treatment. The bromine fraction of halogens in formed trihalomethanes increased with UV dose. This indicates that UV removes bromine atoms from larger molecules that participate in trihalomethane production during post-UV chlorination. Additionally, no significant

New particle formation and growth from methanesulfonic acid, trimethylamine and water.

Science.gov (United States)

Chen, Haihan; Ezell, Michael J; Arquero, Kristine D; Varner, Mychel E; Dawson, Matthew L; Gerber, R Benny; Finlayson-Pitts, Barbara J

2015-05-28

New particle formation from gas-to-particle conversion represents a dominant source of atmospheric particles and affects radiative forcing, climate and human health. The species involved in new particle formation and the underlying mechanisms remain uncertain. Although sulfuric acid is commonly recognized as driving new particle formation, increasing evidence suggests the involvement of other species. Here we study particle formation and growth from methanesulfonic acid, trimethylamine and water at reaction times from 2.3 to 32 s where particles are 2-10 nm in diameter using a newly designed and tested flow system. The flow system has multiple inlets to facilitate changing the mixing sequence of gaseous precursors. The relative humidity and precursor concentrations, as well as the mixing sequence, are varied to explore their effects on particle formation and growth in order to provide insight into the important mechanistic steps. We show that water is involved in the formation of initial clusters, greatly enhancing their formation as well as growth into detectable size ranges. A kinetics box model is developed that quantitatively reproduces the experimental data under various conditions. Although the proposed scheme is not definitive, it suggests that incorporating such mechanisms into atmospheric models may be feasible in the near future.

Biofilm formation on materials into contact with water: hygienic and technical aspects

International Nuclear Information System (INIS)

Bonadonna, L; Memoli, G.; Chiaretti, G.

2008-01-01

Biofilm formation in man-made water systems has a hygienic concern when it is considered that the continuous detachment of this structure in the water flow, condition representing a potential source of contamination of plumbing and a risk for health, allows also pathogen microorganisms to reach consumers. The trend of biofilm formation was evaluated through series of microbiological analyses performed, under controlled conditions, on pipes made of materials that come into contact with drinking water according to the Decree of Ministry of Health n. 174. The investigation showed that, respect to the other materials, the reticulated polyethylene allows to sustain higher microorganisms concentrations. This characteristic was also observed in biofilms developed in condition of water stagnation compared to biofilm risen on surfaces of pipes under water flow [it

Laboratory studies on the effect of ozonation on THM formation in swimming pool water

DEFF Research Database (Denmark)

Hansen, Kamilla Marie Speht; Spiliotopoulou, Aikaterini; Cheema, Waqas Akram

2015-01-01

Water samples from indoor swimming pool were ozonated at different pH values to evaluate the effect of pH on decomposition of ozone in swimming pool water. Furthermore, drinking and pool water were repeatedly ozonated followed by chlorination to evaluate THM formation. Decomposition of ozone...... was not affected by pH in the range relevant to swimming pools (pH 6.8 – 7.8) and a half-life time at 10-12 min was obtained. Repeating the ozonation, the decomposition of ozone increased at the second dose of ozone added (t½,2=8 min) and then decreased again at the third and fourth dose of ozone (t½,3=17 min; t...... chlorine for drinking water as lower TTHM formation occurred than in non-ozonated samples. For pool water, a higher TTHM formation was observed in ozonated than non-ozonated pool water. Thus, it was observed that ozone reacts markedly different in swimming pool water from the known pattern in drinking...

Relationship between organic precursors and N-nitrosodimethylamine (NDMA) formation in tropical water sources.

Science.gov (United States)

Qi, Wang; Fang Yee, Lim; Jiangyong, Hu

2014-12-01

The presence of organic compounds in water sources is one of the concerns in water treatment. They are potential precursors of disinfection byproducts (DBPs) and thus induce health problems in humans. Among the emerging DBPs, carcinogenic compound N-nitrosodimethylamine (NDMA) has been receiving attention during the last decade. This study examined the characteristics of organic components in various water sources and investigated their relationships with NDMA formation. Experiments were carried out on selected water samples from both natural water and wastewater. Results showed similar NDMA formation kinetics for both water sources. However, more contribution of NDMA precursors was found to be from the wastewater due to its higher organic nitrogen content. NDMA formation potential (NDMAFP) of secondary effluent ranged from 264 to 530 ng/L. A correlation study between organic compound characteristics and NDMAFP indicated that the majority of NDMA precursors came from dissolved organic nitrogen (DON) compound with small molecular weight (smaller than 500 Da), with correlation R(2) = 0.898. Although secondary treatment removed more than 90% of NDMA precursors, the remaining precursors in secondary effluent would still pose a challenge for water quality.

Water retention and runoff formation in the Krkonoše Mts

Czech Academy of Sciences Publication Activity Database

Šír, Miloslav; Tesař, Miroslav

2013-01-01

Roč. 50, August (2013), s. 97-106 ISSN 0139-925X R&D Projects: GA TA ČR TA02021451 Institutional support: RVO:67985874 Keywords : mountain hydrology * runoff formation * catchment water retention * soil water movement Subject RIV: DA - Hydrology ; Limnology

Dynamics of biofilm formation in a model drinking water distribution system

DEFF Research Database (Denmark)

Boe-Hansen, Rasmus; Albrechtsen, Hans-Jørgen; Arvin, Erik

2002-01-01

The dynamics of biofilm formation in non-chlorinated groundwater-based drinking water was studied in a model distribution system. The formation of biofilm was closely monitored for a period of 522 days by total bacterial counts (AODC), heterotrophic plate counts (R2A media), and ATP content...

Effects of hydraulic frac fluids and formation waters on groundwater microbial communities

Science.gov (United States)

Krueger, Martin; Jimenez, Nuria

2017-04-01

Shale gas is being considered as a complementary energy resource to other fossil fuels. Its exploitation requires using advanced drilling techniques and hydraulic stimulation (fracking). During fracking operations, large amounts of fluids (fresh water, proppants and chemicals) are injected at high pressures into the formations, to create fractures and fissures, and thus to release gas from the source rock into the wellbore. The injected fluid partly remains in the formation, while up to 40% flows back to the surface, together with reservoir waters, sometimes containing dissolved hydrocarbons, high salt concentrations, etc. The aim of our study was to investigate the potential impacts of frac or geogenic chemicals, frac fluid, formation water or flowback on groudnwater microbial communities. Laboratory experiments under in situ conditions (i.e. at in situ temperature, high pressure) were conducted using groundwater samples from three different locations. Series of microcosms containing R2 broth medium or groundwater spiked with either single frac chemicals (including biocides), frac fluids, artificial reservoir water, NaCl, or different mixtures of reservoir water and frac fluid (to simulate flowback) were incubated in the dark. Controls included non-amended and non-inoculated microcosms. Classical microbiological methods and molecular analyses were used to assess changes in the microbial abundance, community structure and function in response to the different treatments. Microbial communities were quite halotolerant and their growth benefited from low concentrations of reservoir waters or salt, but they were negatively affected by higher concentrations of formation waters, salt, biocides or frac fluids. Changes on the microbial community structure could be detected by T-RFLP. Single frac components like guar gum or choline chloride were used as substrates, while others like triethanolamine or light oil distillate hydrogenated prevented microbial growth in

Identification of combustion intermediates in low-pressure premixed pyridine/oxygen/argon flames.

Science.gov (United States)

Tian, Zhenyu; Li, Yuyang; Zhang, Taichang; Zhu, Aiguo; Qi, Fei

2008-12-25

Combustion intermediates of two low-pressure premixed pyridine/oxygen flames with respective equivalence ratios of 0.56 (C/O/N = 1:4.83:0.20) and 2.10 (C/O/N = 1:1.29:0.20) have been identified with tunable synchrotron vacuum ultraviolet (VUV) photoionization and molecular-beam mass spectrometry techniques. About 80 intermediates in the rich flame and 60 intermediates in the lean flame, including nitrogenous, oxygenated, and hydrocarbon intermediates, have been identified by measurements of photoionization mass spectra and photoionization efficiency spectra. Some radicals and new nitrogenous intermediates are identified in the present work. The experimental results are useful for studying the conversion of volatile nitrogen compounds and understanding the formation mechanism of NO(x) in flames of nitrogenous fuels.

Acid and base recovery from brine solution using PVP intermediate-based bipolar membrane through water splitting technology

Science.gov (United States)

Venugopal, Krishnaveni; Murugappan, Minnoli; Dharmalingam, Sangeetha

2017-07-01

Potable water has become a scarce resource in many countries. In fact, the world is not running out of water, but rather, the relatively fixed quantity is becoming too contaminated for many applications. Hence, the present work was designed to evaluate the desalination efficiency of resin and glass fiber-reinforced Polysulfone polymer-based monopolar and bipolar (BPM) ion exchange membranes (with polyvinyl pyrrolidone as the intermediate layer) on a real sample brine solution for 8 h duration. The prepared ion exchange membranes (IEMs) were characterized using FTIR, SEM, TGA, water absorption, and contact angle measurements. The BPM efficiency, electrical conductivity, salinity, sodium, and chloride ion concentration were evaluated for both prepared and commercial-based IEM systems. The current efficiency and energy consumption values obtained during BPMED process were found to be 45 % and 0.41 Wh for RPSu-PVP-based IEM system and 38 % and 1.60 Wh for PSDVB-based IEM system, respectively.

Project study for the final disposal of intermediate toxicity radioactive wastes (low- and intermediate-level radioactive wastes) in geological formations

International Nuclear Information System (INIS)

1980-08-01

The present report aimed to show variations in the construction- and operation-technical feasibility of a final repository for low- and intermediate-level radioactive wastes. This report represents the summary of a project study given under contract by Nagra with a view to informing a broader public of the technical conception of a final repository. Particular stress was laid on the treatment of the individual system elements of a repository concept during the construction, operation and sealing phases. The essential basis for the project study is the origin, composition and quantity of the wastes to be disposed. The final repository described in this report is foreseen for the reception of the following low- and intermediate-level solid radioactive wastes: wastes from the nuclear power plant operation; secondary wastes from the reprocessing of nuclear fuels; wastes from the decommissioning of nuclear power plants; wastes from research, medicine and industry

Re-initiation of bottom water formation in the East Sea (Japan Sea) in a warming world.

Science.gov (United States)

Yoon, Seung-Tae; Chang, Kyung-Il; Nam, SungHyun; Rho, TaeKeun; Kang, Dong-Jin; Lee, Tongsup; Park, Kyung-Ae; Lobanov, Vyacheslav; Kaplunenko, Dmitry; Tishchenko, Pavel; Kim, Kyung-Ryul

2018-01-25

The East Sea (Japan Sea), a small marginal sea in the northwestern Pacific, is ventilated deeply down to the bottom and sensitive to changing surface conditions. Addressing the response of this marginal sea to the hydrological cycle and atmospheric forcing would be helpful for better understanding present and future environmental changes in oceans at the global and regional scales. Here, we present an analysis of observations revealing a slowdown of the long-term deepening in water boundaries associated with changes of water formation rate. Our results indicate that bottom (central) water formation has been enhanced (reduced) with more (less) oxygen supply to the bottom (central) layer since the 2000s. This paper presents a new projection that allows a three-layered deep structure, which retains bottom water, at least until 2040, contrasting previous results. This projection considers recent increase of slope convections mainly due to the salt supply via air-sea freshwater exchange and sea ice formation and decrease of open-ocean convections evidenced by reduced mixed layer depth in the northern East Sea, resulting in more bottom water and less central water formations. Such vigorous changes in water formation and ventilation provide certain implications on future climate changes.

Effect of Pre-ozonation on Haloacetic Acids Formation in Ganga River Water at Kanpur, India

Science.gov (United States)

Naladala, Nagasrinivasa Rao; Singh, Rambabu; Katiyar, Kumud Lata Devi; Bose, Purnendu; Dutta, Venkatesh

2017-11-01

Almost all natural water bodies which are considered to be sustainable sources of drinking water contain organic matter in dissolved form and pathogens. This dissolved organic matter and pathogens cannot be removed effectively through traditional filtering processes in drinking water treatment plants. Chlorination of such water for disinfection results in large amounts of disinfection by-products (DBPs), mainly trihalomethanes and haloacetic acids (HAAs), which showed many health effects like cancer and reproductive problems in lab animals and in human beings as well. Complete removal of dissolved organic carbon (DOC), which is a precursor compound for HAAs formation, is impossible from a practical point of view; hence, it will be better if DOC activity towards DBPs formation can be reduced via some process. The present article describes the process of pre-ozonating post-coagulated Ganga River water at Kanpur in a continuous flow mode and its effect on HAAs formation. Nearly 58% reduction in HAAs formation was observed during this study at higher doses of ozone.

Formation of hydrogen during heterogeneous thermoradiolysis of water

International Nuclear Information System (INIS)

Rustamov, V.R.; Bugaenko, L.T.; Kerimov, V.K.; Kurbanov, M.A.; Mamedov, S.G.; Ali-Zade, Sh.N.

1986-01-01

At fairly high temperatures, the action of ionizing radiation on water should lead to chain decomposition of water, if in the system there is an acceptor for hydroxyl radical, which transforms it into a hydrogen atom by the reaction OH + X → XO + H, followed by the reaction of hydrogen atoms with a water molecule and formation of molecular hydrogen H + H 2 O → OH. This sequence has been realized in a homogeneous system containing carbon monoxide as an acceptor-transformer. It has been suggested that the same reactions can take place on the surface of solid bodies as in the gaseous phase. In the present work, results are reported of a study of radiational-chemical processes in water at 400 0 C in the presence of a highly dispersed iron(III) oxide with a specific surface of 5 x 10 3 m 2 /kg

Formation of RNA Granule-Derived Capsid Assembly Intermediates Appears To Be Conserved between Human Immunodeficiency Virus Type 1 and the Nonprimate Lentivirus Feline Immunodeficiency Virus.

Science.gov (United States)

Reed, Jonathan C; Westergreen, Nick; Barajas, Brook C; Ressler, Dylan T B; Phuong, Daryl J; Swain, John V; Lingappa, Vishwanath R; Lingappa, Jaisri R

2018-05-01

FIV Gag progresses through a pathway of immature capsid assembly intermediates derived from host RNA granules, as shown for HIV-1 Gag. Here we showed that FIV Gag forms complexes that resemble HIV-1 capsid assembly intermediates in size and in their association with ABCE1 and DDX6, two host facilitators of HIV-1 immature capsid assembly that are found in HIV-1 assembly intermediates. Our studies also showed that known and novel assembly-defective FIV Gag mutants fail to progress past putative intermediates in a pattern resembling that observed for HIV-1 Gag mutants. Finally, we used imaging to demonstrate colocalization of FIV Gag with ABCE1 and with the RNA granule protein DCP2. Thus, we conclude that formation of assembly intermediates derived from host RNA granules is likely conserved between primate and nonprimate lentiviruses and could provide targets for future antiviral strategies. Copyright © 2018 American Society for Microbiology.

Influence of infiltrated water on the change of formation water and oil permeability of crude oil bearing rocks

Energy Technology Data Exchange (ETDEWEB)

Cubric, S

1970-09-01

A brief desription is given of the causes of permeability reduction of oil-bearing rocks, due to well damage during the drilling and well completion or when working over wells. The physical properties of 2-phase flow (crude oil-water) and the possibility of increasing the existing permeability of the formation, because of the water infiltrated from the well into the crude oil layer, are described in detail. Field examples show that there are such cases, and that the artificially increased existing permeability of water-bearing rocks can be reduced and even brought to normal, if the adjacent formation zone layer is treated with surfactants (e.g., Hyflo dissolved in crude oil).

Comprehensive determination of macrolide antibiotics, their synthesis intermediates and transformation products in wastewater effluents and ambient waters by liquid chromatography-tandem mass spectrometry.

Science.gov (United States)

Senta, Ivan; Krizman-Matasic, Ivona; Terzic, Senka; Ahel, Marijan

2017-08-04

Macrolide antibiotics are a prominent group of emerging contaminants frequently found in wastewater effluents and wastewater-impacted aquatic environments. In this work, a novel analytical method for simultaneous determination of parent macrolide antibiotics (azithromycin, erythromycin, clarithromycin and roxithromycin), along with their synthesis intermediates, byproducts, metabolites and transformation products in wastewater and surface water was developed and validated. Samples were enriched using solid-phase extraction on Oasis HLB cartridges and analyzed by reversed-phase liquid chromatography coupled to electrospray ionization tandem mass spectrometry. The target macrolide compounds were separated on an ACE C18 PFP column and detected using multiple reaction monitoring in positive ionization polarity. The optimized method, which included an additional extract clean-up on strong anion-exchange cartridges (SAX), resulted in high recoveries and accuracies, low matrix effects and improved chromatographic separation of the target compounds, even in highly complex matrices, such as raw wastewater. The developed method was applied to the analysis of macrolide compounds in wastewater and river water samples from Croatia. In addition to parent antibiotics, several previously unreported macrolide transformation products and/or synthesis intermediates were detected in municipal wastewater, some of them reaching μg/L levels. Moreover, extremely high concentrations of macrolides up to mg/L level were found in pharmaceutical industry effluents, indicating possible importance of this source to the total loads into ambient waters. The results revealed a significant contribution of synthesis intermediates and transformation products to the overall mass balance of macrolides in the aquatic environment. Copyright © 2017. Published by Elsevier B.V.

Formation of Intermediate Plutonic Rocks by Magma Mixing: the Shoshonite Suite of Timna, Southern Israel.

Science.gov (United States)

Fox, S.; Katzir, Y.

2017-12-01

In magmatic series considered to form by crystal fractionation intermediate rocks are usually much less abundant than expected. Yet, intermediate plutonic rocks, predominantly monzodiorites, are very abundant in the Neoproterozoic Timna igneous complex, S. Israel. A previously unnoticed plutonic shoshonitic suite was recently defined and mapped in Timna (Litvinovsky et al., 2015). It mostly comprises intermediate rocks in a seemingly 'continuous' trend from monzodiorite through monzonite to quartz syenite. Macroscale textures including gradational boundaries of mafic and felsic rocks and MME suggest that magma mixing is central in forming intermediate rocks in Timna. Our petrographic, microtextural and mineral chemistry study delineates the mode of incipient mixing, ultimate mingling and crystal equilibration in hybrid melts. An EMP study of plagioclase from rocks across the suite provides a quantitative evaluation of textures indicative of magma mixing/mingling, including recurrent/patchy zoning, Ca spike, boxy/sponge cellular texture and anti-Rapakivi texture. Each texture has an affinity to a particular mixing region. A modal count of these textures leads to a kinetic mixing model involving multi temporal and spatial scales necessary to form the hybrid intermediate rocks. A `shell'-like model for varying degrees of mixing is developed with the more intensive mixing at the core and more abundant felsic and mafic end-members towards the outer layer. REE patterns in zircon shows that it originated from both mafic and felsic parent melts. Whole rock Fe vs Sr plot suggests a two-stage mixing between the monzogabbro and quartz-syenite producing first mesocratic syenite, and subsequent mixing with a fractionating monzogabbro resulting in monzonitic compositions. A fractionating monzogabbro intruded into a syenitic melt sequentially. While slowly cooling, the monzogabbro heated the immediate syenitic melt, lowering the viscosity and rheological obstruction to overturn

Deep formation waters of Western Europe, Russia and North America characterised by sodium, calcium, magnesium and chloride concentrations

Science.gov (United States)

Bozau, Elke; Hemme, Christina; Sattler, Carl-Diedrich; van Berk, Wolfgang

2015-04-01

Deep formation water can be classified according to depth, temperature, and salinity (e.g., Graf et al. 1966, Kharaka & Hanor 2007). Most of the deep formation waters contain dissolved solids in excess of sea water. The hydrogeochemical development of formation water has been discussed for a long time. It is widely accepted that deep aquifers are influenced by the meteoric cycle and geochemical processes within the crust (e.g., Hebig et al. 2012). Similar hydrogeochemical signatures are found in deep formation waters of all continents and can be explained by general geochemical processes within the deep reservoirs (e.g., Land 1995). Therefore, data of deep formation waters from Western Europe, Russia, and North America are collected and classified by the major water components. The data are used to identify important hydrogeochemical processes (e.g., halite dissolution and albitisation) leading to different compositions of formation water. Two significant water types are identified: Na-Cl water and Na-Ca-Cl water. Based on the collected hydrogeochemical data, development trends are stated for the formation waters, and albitisation is favoured as the main process for calcium enrichment. Furthermore, differences of formation water according to stratigraphical units are shown for deep reservoirs of the North German Basin and the North Sea. References: Graf, D.L., 1982. Chemical osmosis, reverse chemical osmosis, and the origin of subsurface brines. Geochimica Cosmochimica Acta 46, 1431-1448. Hebig, K.H., Ito, N., Scheytt, T., Marui, A., 2012. Review: Deep groundwater research with focus on Germany. Hydrogeology Journal 20, 227-243. Kharaka, Y.K., Hanor, J.S., 2007. Deep fluids in continents: I. Sedimentary Basins. Treatise on Geochemistry 5, 1-48. Land, L.S., 1995. The role of saline formation water in the crustal cycling. Aquatic Geochemistry 1, 137-145. Acknowledgements: The presented data are results of the collaborative research program "gebo" (Geothermal energy

Intermediate uveitis

Directory of Open Access Journals (Sweden)

Babu B

2010-01-01

Full Text Available Intermediate uveitis (IU is described as inflammation in the anterior vitreous, ciliary body and the peripheral retina. In the Standardization of Uveitis Nomenclature (SUN working group′s international workshop for reporting clinical data the consensus reached was that the term IU should be used for that subset of uveitis where the vitreous is the major site of the inflammation and if there is an associated infection (for example, Lyme disease or systemic disease (for example, sarcoidosis. The diagnostic term pars planitis should be used only for that subset of IU where there is snow bank or snowball formation occurring in the absence of an associated infection or systemic disease (that is, "idiopathic". This article discusses the clinical features, etiology, pathogenesis, investigations and treatment of IU.

Vegetation pattern formation in a fog-dependent ecosystem.

Science.gov (United States)

Borthagaray, Ana I; Fuentes, Miguel A; Marquet, Pablo A

2010-07-07

Vegetation pattern formation is a striking characteristic of several water-limited ecosystems around the world. Typically, they have been described on runoff-based ecosystems emphasizing local interactions between water, biomass interception, growth and dispersal. Here, we show that this situation is by no means general, as banded patterns in vegetation can emerge in areas without rainfall and in plants without functional root (the Bromeliad Tillandsia landbeckii) and where fog is the principal source of moisture. We show that a simple model based on the advection of fog-water by wind and its interception by the vegetation can reproduce banded patterns which agree with empirical patterns observed in the Coastal Atacama Desert. Our model predicts how the parameters may affect the conditions to form the banded pattern, showing a transition from a uniform vegetated state, at high water input or terrain slope to a desert state throughout intermediate banded states. Moreover, the model predicts that the pattern wavelength is a decreasing non-linear function of fog-water input and slope, and an increasing function of plant loss and fog-water flow speed. Finally, we show that the vegetation density is increased by the formation of the regular pattern compared to the density expected by the spatially homogeneous model emphasizing the importance of self-organization in arid ecosystems. (c) 2010 Elsevier Ltd. All rights reserved.

Origin of late pleistocene formation water in Mexican oil reservoirs

Energy Technology Data Exchange (ETDEWEB)

Birkle, P. [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

2004-07-01

Brine water invasion into petroleum reservoirs, especially in sedimentary basins, are known from a variety of global oil field, such as the Western Canada sedimentary basin and, the central Mississippi Salt Dome basin (Kharaka et al., 1987). The majority of oil wells, especially in the more mature North American fields, produce more water than they do oil (Peachey et al., 1998). In the case of Mexican oil fields, increasing volumes of invading water into the petroleum wells were detected during the past few years. Major oil reserves in the SE-part of the Gulf of Mexico are economically affected due to decreases in production rate, pipeline corrosion and well closure. The origin of deep formation water in many sedimentary basins is still controversial: Former hypothesis mainly in the 60's, explained the formation of formation water by entrapment of seawater during sediment deposition. Subsequent water-rock interaction processes explain the chemical evolution of hydrostatic connate water. More recent hydrodynamic models, mainly based on isotopic data, suggest the partial migration of connate fluids, whereas the subsequent invasion of surface water causes mixing processes (Carpenter 1978). As part of the presented study, a total of 90 oil production wells were sampled from 1998 to 2004 to obtain chemical (Major and trace elements) and isotopic composition ({sup 2}H, {sup 13}C, {sup 14}C, {sup 18}O {sup 36}Cl, {sup 37}Cl, {sup 87}Sr, {sup 129}I, tritium) of deep formation water at the Mexican Gulf coast. Samples were extracted from carbonate-type reservoirs of the oil fields Luna, Samaria-Sitio Grande, Jujo-Tecominoac (on-shore), and Pol-Chuc (off-shore, including Abkatun, Batab, Caan, and Taratunich) at a depth between 2,900 m b.s.l. and 6,100 m b.s.l. During the field work, the influence of atmospheric contamination e.g. by CO{sub 2}-atmospheric input was avoided by using an interval sampler to get in-situ samples from the extraction zone of selected bore holes

Secondary organic aerosol formation from semi- and intermediate-volatility organic compounds and glyoxal: Relevance of O/C as a tracer for aqueous multiphase chemistry

Science.gov (United States)

Waxman, Eleanor M.; Dzepina, Katja; Ervens, Barbara; Lee-Taylor, Julia; Aumont, Bernard; Jimenez, Jose L.; Madronich, Sasha; Volkamer, Rainer

2013-03-01

The role of aqueous multiphase chemistry in the formation of secondary organic aerosol (SOA) remains difficult to quantify. We investigate it here by testing the rapid formation of moderate oxygen-to-carbon (O/C) SOA during a case study in Mexico City. A novel laboratory-based glyoxal-SOA mechanism is applied to the field data, and explains why less gas-phase glyoxal mass is observed than predicted. Furthermore, we compare an explicit gas-phase chemical mechanism for SOA formation from semi- and intermediate-volatility organic compounds (S/IVOCs) with empirical parameterizations of S/IVOC aging. The mechanism representing our current understanding of chemical kinetics of S/IVOC oxidation combined with traditional SOA sources and mixing of background SOA underestimates the observed O/C by a factor of two at noon. Inclusion of glyoxal-SOA with O/C of 1.5 brings O/C predictions within measurement uncertainty, suggesting that field observations can be reconciled on reasonable time scales using laboratory-based empirical relationships for aqueous chemistry.

Synchrotron photoionization mass spectrometry study of intermediates in fuel-rich 1,2-dimethoxyethane flame

International Nuclear Information System (INIS)

Lin, Z. K.; Han, D. L.; Li, S. F.; Li, Y. Y.; Yuan, T.

2009-01-01

Intermediates in a fuel-rich premixed laminar 1,2-dimethoxyethane (DME) flame are studied by molecular beam mass spectrometry combined with tunable synchrotron vacuum ultraviolet photoionization. About 30 intermediate species are identified in the present work, and their mole fraction profiles are evaluated. The experimental results show that the formations of intermediates, both hydrocarbons and oxygenated hydrocarbons, are closely linked to the structure of fuel, which is consistent with the previous reports. Species produced from H atom abstraction and beta scission of DME usually have much higher concentrations than others. The oxygen atoms in DME are considered to act as partitions of the primary intermediates; therefore farther reactions among these primary intermediates are difficult to occur, resulting in absence of most large intermediate species.

Examining the Center: Positions, Dominance, and Star Formation Rates of Most Massive Group Galaxies at Intermediate Redshift

Science.gov (United States)

Connelly, Jennifer L.; Parker, Laura C.; McGee, Sean; Mulchaey, John S.; Finoguenov, Alexis; Balogh, Michael; Wilman, David; Group Environment Evolution Collaboration

2015-01-01

The group environment is believed to be the stage for many galaxy transformations, helping evolve blue star-forming galaxies to red passive ones. In local studies of galaxy clusters, the central member is usually a single dominant giant galaxy at the center of the potential with little star formation thought to be the result of galaxy mergers. In nearby groups, a range of morphologies and star formation rates are observed and the formation history is less clear. Further, the position and dominance of the central galaxy cannot be assumed in groups, which are less massive and evolved than clusters. To understand the connections between global group properties and properties of the central group galaxy at intermediate redshift, we examine galaxy groups from the Group Environment and Evolution Collaboration (GEEC) catalog, including both optically- and X-ray-selected groups at redshift z~0.4. The sample is diverse, containing a range in overall mass and evolutionary state. The number of groups is significant, membership is notably complete, and measurements span the IR to the UV allowing the properties of the members to be connected to those of the host groups. Having investigated trends in the global group properties previously, including mass and velocity substructure, we turn our attention now to the galaxy populations, focusing on the central regions of these systems. The most massive and second most massive group galaxies are identified by their stellar mass. The positions of the most massive galaxies (MMGs) are determined with respect to both the luminosity-weighted and X-ray center. Star formation rates are used to explore the fraction of passive/quiescent versus star-forming MMGs and the dominance of the MMGs in our group sample is also tested. Determinations of these characteristics and trends constitute the important first steps toward a detailed understanding of the relationships between the properties of host groups and their most massive galaxies and the

Binding of Divalent Cations to Polygalacturonate: A Mechanism Driven by the Hydration Water.

Science.gov (United States)

Huynh, Uyen T D; Lerbret, Adrien; Neiers, Fabrice; Chambin, Odile; Assifaoui, Ali

2016-02-11

We have investigated the interactions between polygalacturonate (polyGal) and four divalent cations (M(2+) = Ba(2+), Ca(2+), Mg(2+), Zn(2+)) that differ in size and affinity for water. Our results evidence that M(2+)-polyGal interactions are intimately linked to the affinity of M(2+) for water. Mg(2+) interacts so strongly with water that it remains weakly bound to polyGal (polycondensation) by sharing water molecules from its first coordination shell with the carboxylate groups of polyGal. In contrast, the other cations form transient ionic pairs with polyGal by releasing preferentially one water molecule (for Zn(2+)) or two (for Ca(2+) and Ba(2+)), which corresponds to monodentate and bidentate binding modes with carboxylates, respectively. The mechanism for the binding of these three divalent cations to polyGal can be described by two steps: (i) monocomplexation and formation of point-like cross-links between polyGal chains (at low M(2+)/Gal molar ratios, R) and (ii) dimerization (at higher R). The threshold molar ratio, R*, between these two steps depends on the nature of divalent cations and is lower for calcium ions (R* 0.3). This difference may be explained by the intermediate affinity of Ca(2+) for water with respect to those of Zn(2+) and Ba(2+), which may induce the formation of cross-links of intermediate flexibility. By comparison, the lower and higher flexibilities of the cross-links formed by Zn(2+) and Ba(2+), respectively, may shift the formation of dimers to higher molar ratios (R*).

Renewable Formate from C-H Bond Formation with CO2: Using Iron Carbonyl Clusters as Electrocatalysts.

Science.gov (United States)

Loewen, Natalia D; Neelakantan, Taruna V; Berben, Louise A

2017-09-19

As a society, we are heavily dependent on nonrenewable petroleum-derived fuels and chemical feedstocks. Rapid depletion of these resources and the increasingly evident negative effects of excess atmospheric CO 2 drive our efforts to discover ways of converting excess CO 2 into energy dense chemical fuels through selective C-H bond formation and using renewable energy sources to supply electrons. In this way, a carbon-neutral fuel economy might be realized. To develop a molecular or heterogeneous catalyst for C-H bond formation with CO 2 requires a fundamental understanding of how to generate metal hydrides that selectively donate H - to CO 2 , rather than recombining with H + to liberate H 2 . Our work with a unique series of water-soluble and -stable, low-valent iron electrocatalysts offers mechanistic and thermochemical insights into formate production from CO 2 . Of particular interest are the nitride- and carbide-containing clusters: [Fe 4 N(CO) 12 ] - and its derivatives and [Fe 4 C(CO) 12 ] 2- . In both aqueous and mixed solvent conditions, [Fe 4 N(CO) 12 ] - forms a reduced hydride intermediate, [H-Fe 4 N(CO) 12 ] - , through stepwise electron and proton transfers. This hydride selectively reacts with CO 2 and generates formate with >95% efficiency. The mechanism for this transformation is supported by crystallographic, cyclic voltammetry, and spectroelectrochemical (SEC) evidence. Furthermore, installation of a proton shuttle onto [Fe 4 N(CO) 12 ] - facilitates proton transfer to the active site, successfully intercepting the hydride intermediate before it reacts with CO 2 ; only H 2 is observed in this case. In contrast, isoelectronic [Fe 4 C(CO) 12 ] 2- features a concerted proton-electron transfer mechanism to form [H-Fe 4 C(CO) 12 ] 2- , which is selective for H 2 production even in the presence of CO 2 , in both aqueous and mixed solvent systems. Higher nuclearity clusters were also studied, and all are proton reduction electrocatalysts, but none

Identifying and Remediating High Water Production Problems in Basin-Centered Formations

Energy Technology Data Exchange (ETDEWEB)

R.L. Billingsley

2005-12-01

Through geochemical analyses of produced waters, petrophysics, and reservoir simulation we developed concepts and approaches for mitigating unwanted water production in tight gas reservoirs and for increasing recovery of gas resources presently considered noncommercial. Only new completion research (outside the scope of this study) will validate our hypothesis. The first task was assembling and interpreting a robust regional database of historical produced-water analyses to address the production of excessive water in basin-centered tight gas fields in the Greater Green (GGRB ) and Wind River basins (WRB), Wyoming. The database is supplemented with a sampling program in currently active areas. Interpretation of the regional water chemistry data indicates most produced waters reflect their original depositional environments and helps identify local anomalies related to basement faulting. After the assembly and evaluation phases of this project, we generated a working model of tight formation reservoir development, based on the regional nature and occurrence of the formation waters. Through an integrative approach to numerous existing reservoir concepts, we synthesized a generalized development scheme organized around reservoir confining stress cycles. This single overarching scheme accommodates a spectrum of outcomes from the GGRB and Wind River basins. Burial and tectonic processes destroy much of the depositional intergranular fabric of the reservoir, generate gas, and create a rock volume marked by extremely low permeabilities to gas and fluids. Stress release associated with uplift regenerates reservoir permeability through the development of a penetrative grain bounding natural fracture fabric. Reservoir mineral composition, magnitude of the stress cycle and local tectonics govern the degree, scale and exact mechanism of permeability development. We applied the reservoir working model to an area of perceived anomalous water production. Detailed water analyses

Estimating carbonate parameters from hydrographic data for the intermediate and deep waters of the Southern Hemisphere oceans

Science.gov (United States)

Bostock, H. C.; Mikaloff Fletcher, S. E.; Williams, M. J. M.

2013-10-01

Using ocean carbon data from global datasets, we have developed several multiple linear regression (MLR) algorithms to estimate alkalinity and dissolved inorganic carbon (DIC) in the intermediate and deep waters of the Southern Hemisphere (south of 25° S) from only hydrographic data (temperature, salinity and dissolved oxygen). A Monte Carlo experiment was used to identify a potential density (σθ) of 27.5 as an optimal break point between the two regimes with different MLR algorithms. The algorithms provide a good estimate of DIC (R2=0.98) and alkalinity (R2=0.91), and excellent agreement for aragonite and calcite saturation states (R2=0.99). Combining the algorithms with the CSIRO Atlas of Regional Seas (CARS), we have mapped the calcite saturation horizon (CSH) and aragonite saturation horizon (ASH) for the Southern Ocean at a spatial resolution of 0.5°. These maps are more detailed and more consistent with the oceanography than the previously gridded GLODAP data. The high-resolution ASH map reveals a dramatic circumpolar shoaling at the polar front. North of 40° S the CSH is deepest in the Atlantic (~ 4000 m) and shallower in the Pacific Ocean (~ 2750 m), while the CSH sits between 3200 and 3400 m in the Indian Ocean. The uptake of anthropogenic carbon by the ocean will alter the relationships between DIC and hydrographic data in the intermediate and deep waters over time. Thus continued sampling will be required, and the MLR algorithms will need to be adjusted in the future to account for these changes.

Estimating carbonate parameters from hydrographic data for the intermediate and deep waters of the Southern Hemisphere oceans

Directory of Open Access Journals (Sweden)

H. C. Bostock

2013-10-01

Full Text Available Using ocean carbon data from global datasets, we have developed several multiple linear regression (MLR algorithms to estimate alkalinity and dissolved inorganic carbon (DIC in the intermediate and deep waters of the Southern Hemisphere (south of 25° S from only hydrographic data (temperature, salinity and dissolved oxygen. A Monte Carlo experiment was used to identify a potential density (σθ of 27.5 as an optimal break point between the two regimes with different MLR algorithms. The algorithms provide a good estimate of DIC (R2=0.98 and alkalinity (R2=0.91, and excellent agreement for aragonite and calcite saturation states (R2=0.99. Combining the algorithms with the CSIRO Atlas of Regional Seas (CARS, we have mapped the calcite saturation horizon (CSH and aragonite saturation horizon (ASH for the Southern Ocean at a spatial resolution of 0.5°. These maps are more detailed and more consistent with the oceanography than the previously gridded GLODAP data. The high-resolution ASH map reveals a dramatic circumpolar shoaling at the polar front. North of 40° S the CSH is deepest in the Atlantic (~ 4000 m and shallower in the Pacific Ocean (~ 2750 m, while the CSH sits between 3200 and 3400 m in the Indian Ocean. The uptake of anthropogenic carbon by the ocean will alter the relationships between DIC and hydrographic data in the intermediate and deep waters over time. Thus continued sampling will be required, and the MLR algorithms will need to be adjusted in the future to account for these changes.

Far from the intermediate nuclear field

International Nuclear Information System (INIS)

Dietrich, K.; Wagner, G.J.; Gregoire, C.; Campi, X.; Silvestre-Brac, B.; Platchkov, S.; Mayer, B.; Abgrall, Y.; Bohigas, O.; Grange, P.; Signarbieux, C.

1988-01-01

Pairing correlations in nuclear physics; the BCS state and quasi-particles; the layer model; collision effects on nuclear dynamics; the theory of cluster formation (application to nucleus fragmentation); short range correlations (few-particle systems); deuterium electron scattering; dibaryonic resonances; traditional and exotic hadron probes of nuclear structure; spectral fluctuations and chaotic motion; corrections to the intermediate nuclear field (nonrelativistic and other effects); and heavy nuclei splitting and nuclear superfluidity are introduced [fr

Oxidative demethylation of lanosterol in cholesterol biosynthesis: accumulation of sterol intermediates

International Nuclear Information System (INIS)

Shafiee, A.; Trzaskos, J.M.; Paik, Y.K.; Gaylor, J.L.

1986-01-01

With [ 3 H-24,25]-dihydrolanosterol as substrate, large-scale metabolic formation of intermediates of lanosterol demethylation was carried out to identify all compounds in the metabolic process. Utilizing knowledge of electron transport of lanosterol demethylation, we interrupted the demethylation reaction allowing accumulation and confirmation of the structure of the oxygenated intermediates lanost-8-en-3 beta,32-diol and 3 beta-hydroxylanost-8-en-32-al, as well as the demethylation product 4,4-dimethyl-cholesta-8,14-dien-3 beta-ol. Further metabolism of the delta 8.14-diene intermediate to a single product 4,4-dimethyl-cholest-8-en-3 beta-ol occurs under interruption conditions in the presence of 0.5 mM CN-1. With authentic compounds, each intermediate has been rigorously characterized by high performance liquid chromatography and gas-liquid chromatography plus mass spectral analysis of isolated and derivatized sterols. Intermediates that accumulated in greater abundance were further characterized by ultraviolet, 1 H-NMR, and infrared spectroscopy of the isolated sterols

On the influence of water subcooling and melt jet parameters on debris formation

Energy Technology Data Exchange (ETDEWEB)

Manickam, Louis, E-mail: louis@safety.sci.kth.se; Kudinov, Pavel; Ma, Weimin; Bechta, Sevostian; Grishchenko, Dmitry

2016-12-01

Highlights: • Melt and water configuration effects on debris formation is studied experimentally. • Melt superheat and water subcooling are most influential compared to jet size. • Melt-water configuration and material properties influence particle fracture rate. • Results are compared with large scale experiments to study effect of spatial scales. - Abstract: Breakup of melt jet and formation of a porous debris bed at the base-mat of a flooded reactor cavity is expected during the late stages of a severe accident in light water reactors. Debris bed coolability is determined by the bed properties including particle size, morphology, bed height and shape as well as decay heat. Therefore understanding of the debris formation phenomena is important for assessment of debris bed coolability. A series of experiments was conducted in MISTEE-Jet facility by discharging binary-oxide mixtures of WO{sub 3}–Bi{sub 2}O{sub 3} and WO{sub 3}–ZrO{sub 2} into water in order to investigate properties of resulting debris. The effect of water subcooling, nozzle diameter and melt superheat was addressed in the tests. Experimental results reveal significant influence of water subcooling and melt superheat on debris size and morphology. Significant differences in size and morphology of the debris at different melt release conditions is attributed to the competition between hydrodynamic fragmentation of liquid melt and thermal fracture of the solidifying melt droplets. The particle fracture rate increases with increased subcooling. Further the results are compared with the data from larger scale experiments to discern the effects of spatial scales. The present work provides data that can be useful for validation of the codes used for the prediction of debris formation phenomena.

Potentiometric surfaces of the intermediate aquifer system, west-central Florida, May, 1993

Science.gov (United States)

Mularoni, R.A.

1994-01-01

The intermediate aquifer system underlies a 5000-sq-mi area including De Soto, Sarasota, Hardee, Manatee, and parts of Charlotte, Hillsborough, Highlands, and Polk Counties, Florida. It is overlain by the surf@cial aquifer system and underlain by the Floridan aquifer system. The potentiometric surface of the intermediate aquifer system was mapped by determining the altitude of water levels in a network of wells and represented on a map by contours that connect points of equal altitude. This map represents water-level conditions near the end of the spring dry season when ground- water withdrawals for agricultural use were high. The cumulative rainfall for the study area was 4.84 inches above normal for the period from June 1992 to May 1993. Hydrographs for selected wells indicated that the annual and seasonal fluctuations of the water levels were generally large (greater than 15 feet) in the central interior region where water demand for irrigation is high during the fall and spring. Seasonal fluctuations were smaller in the northern recharge area where water use is predominantly for public supply. Water levels measured in May 1993 for the composite intermediate aquifer potentiometric surface were lower than those measured in May or September 1992. A cone of depression exists in the potentiometric surface for the composite aquifer system at Warm Mineral Springs, which is a natural discharge point from this system.

Geometrical constraint on the localization of deep water formation

Science.gov (United States)

Ferreira, D.; Marshall, J.

2008-12-01

That deep water formation occurs in the North Atlantic and not North Pacific is one of the most notable features of the present climate. In an effort to build a system able to mimic such basic aspects of climate using a minimal description, we study here the influence of ocean geometry on the localization of deep water formation. Using the MIT GCM, two idealized configurations of an ocean-atmosphere-sea ice climate system are studied: Drake and Double-Drake. In Drake, one narrow barrier extends from the North Pole to 35°S while, in Double-Drake, two such barriers set 90° apart join at the North Pole to delimit a Small and a Large basin. Despite the different continental configurations, the two climates are strikingly similar in the zonal average (almost identical heat and fresh water transports, and meridional overturning circulation). However, regional circulations in the Small and Large basins exhibit distinctive Atlantic-like and Pacific-like characteristics: the Small basin is warmer and saltier than the Large one, concentrates dense water formation and deep overturning circulation and achieve the largest fraction of the northward ocean heat transport. We show that the warmer temperature and higher evaporation over the Small basin is not its distinguishing factor. Rather, it is the width of the basin in relation to the zonal fetch of the precipitation pattern. This generates a deficit/excess of precipitation over the Small/Large basin: a fraction of the moisture evaporated from the Small basin is transported zonally and rains out over the Large basin. This creates a salt contrast between the 2 basins, leading to the localization of deep convection in the salty Small basin. Finally, given on the broad similarities between the Double-Drake and real World, we suggest that many gross features that define the present climate are a consequence of 2 asymmetries: a meridional asymmetry (a zonally unblocked southern/blocked northern ocean) and a zonal one (a small and

Transformation of polyfluorinated compounds in natural waters by advanced oxidation processes.

Science.gov (United States)

Anumol, Tarun; Dagnino, Sonia; Vandervort, Darcy R; Snyder, Shane A

2016-02-01

The presence of perfluorocarboxylic acids (PFCAs) in source and finished drinking waters is a concern with studies showing bioaccumulation and adverse toxicological effects in wildlife and potentially humans. Per/Polyfluoroalkyl substances (PFAS) such as fluorotelomer alcohols have been identified as precursors for PFCAs in biological pathways. In this study, we investigated the fate of 6:2 and 8:2 homologues of the fluorotelomer unsaturated carboxylic acids (FTUCAs) during advanced oxidation process (AOPs). Results showed 6:2 FTUCA and 8:2 FTUCA transformed into 6-C PFCA (PFHxA) and 8-C PFCA (PFOA) respectively with very little other PFCA formation for all AOPs. The degradation of 6:2 FTUCA and 8:2 FTUCA was greater in the GW compared to SW for the ozone processes but similar for UV/H2O2. The formation of n-C PFCA followed O3>O3/H2O2 at same dose and UV/H2O2 had much lower formation at the doses tested. Non-targeted analysis with the LC-MS-qTOF indicated the production of other PFCAs which contribute to the total mass balance, although no intermediate product was discovered indicating a rapid and direct transformation from the FTUCAs to the PFCAs and/or significant volatilization of intermediates. With the use of AOPs essential to water reuse treatment schemes, this work raises concerns over the risk of potential formation of PFCAs in the treatment and their adverse health effects in finished drinking water. Copyright © 2015 Elsevier Ltd. All rights reserved.

Processing and validation of intermediate energy evaluated data files

International Nuclear Information System (INIS)

2000-01-01

Current accelerator-driven and other intermediate energy technologies require accurate nuclear data to model the performance of the target/blanket assembly, neutron production, activation, heating and damage. In a previous WPEC subgroup, SG13 on intermediate energy nuclear data, various aspects of intermediate energy data, such as nuclear data needs, experiments, model calculations and file formatting issues were investigated and categorized to come to a joint evaluation effort. The successor of SG13, SG14 on the processing and validation of intermediate energy evaluated data files, goes one step further. The nuclear data files that have been created with the aforementioned information need to be processed and validated in order to be applicable in realistic intermediate energy simulations. We emphasize that the work of SG14 excludes the 0-20 MeV data part of the neutron evaluations, which is supposed to be covered elsewhere. This final report contains the following sections: section 2: a survey of the data files above 20 MeV that have been considered for validation in SG14; section 3: a summary of the review of the 150 MeV intermediate energy data files for ENDF/B-VI and, more briefly, the other libraries; section 4: validation of the data library against an integral experiment with MCNPX; section 5: conclusions. (author)

Kinetics of a Criegee intermediate that would survive high humidity and may oxidize atmospheric SO2.

Science.gov (United States)

Huang, Hao-Li; Chao, Wen; Lin, Jim Jr-Min

2015-09-01

Criegee intermediates are thought to play a role in atmospheric chemistry, in particular, the oxidation of SO2, which produces SO3 and subsequently H2SO4, an important constituent of aerosols and acid rain. However, the impact of such oxidation reactions is affected by the reactions of Criegee intermediates with water vapor, because of high water concentrations in the troposphere. In this work, the kinetics of the reactions of dimethyl substituted Criegee intermediate (CH3)2COO with water vapor and with SO2 were directly measured via UV absorption of (CH3)2COO under near-atmospheric conditions. The results indicate that (i) the water reaction with (CH3)2COO is not fast enough (kH2O SO2 at a near-gas-kinetic-limit rate (kSO2 = 1.3 × 10(-10) cm(3) s(-1)). These observations imply a significant fraction of atmospheric (CH3)2COO may survive under humid conditions and react with SO2, very different from the case of the simplest Criegee intermediate CH2OO, in which the reaction with water dimer predominates in the CH2OO decay under typical tropospheric conditions. In addition, a significant pressure dependence was observed for the reaction of (CH3)2COO with SO2, suggesting the use of low pressure rate may underestimate the impact of this reaction. This work demonstrates that the reactivity of a Criegee intermediate toward water vapor strongly depends on its structure, which will influence the main decay pathways and steady-state concentrations for various Criegee intermediates in the atmosphere.

The inhibition of methane hydrate formation by water alignment underneath surface adsorption of surfactants

Energy Technology Data Exchange (ETDEWEB)

Nguyen, Ngoc N.; Nguyen, Anh V.; Dang, Liem X.

2017-06-01

Sodium dodecyl sulfate (SDS) has been widely shown to strongly promote the formation of methane hydrate. Here we show that SDS displays an extraordinary inhibition effect on methane hydrate formation when the surfactant is used in sub-millimolar concentration (around 0.3 mM). We have also employed Sum Frequency Generation vibrational spectroscopy (SFG) and molecular dynamics simulation (MDS) to elucidate the molecular mechanism of this inhibition. The SFG and MDS results revealed a strong alignment of water molecules underneath surface adsorption of SDS in its sub-millimolar solution. Interestingly, both the alignment of water and the inhibition effect (in 0.3 mM SDS solution) went vanishing when an oppositely-charged surfactant (tetra-n-butylammonium bromide, TBAB) was suitably added to produce a mixed solution of 0.3 mM SDS and 3.6 mM TBAB. Combining structural and kinetic results, we pointed out that the alignment of water underneath surface adsorption of dodecyl sulfate (DS-) anions gave rise to the unexpected inhibition of methane hydration formation in sub-millimolar solution of SDS. The adoption of TBAB mitigated the SDS-induced electrostatic field at the solution’s surface and, therefore, weakened the alignment of interfacial water which, in turn, erased the inhibition effect. We discussed this finding using the concept of activation energy of the interfacial formation of gas hydrate. The main finding of this work is to reveal the interplay of interfacial water in governing gas hydrate formation which sheds light on a universal molecular-scale understanding of the influence of surfactants on gas hydrate formation. This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. The calculations were carried out using computer resources provided by the Office of Basic Energy Sciences.

Formate Formation and Formate Conversion in Biological Fuels Production

Directory of Open Access Journals (Sweden)

Bryan R. Crable

2011-01-01

Full Text Available Biomethanation is a mature technology for fuel production. Fourth generation biofuels research will focus on sequestering CO2 and providing carbon-neutral or carbon-negative strategies to cope with dwindling fossil fuel supplies and environmental impact. Formate is an important intermediate in the methanogenic breakdown of complex organic material and serves as an important precursor for biological fuels production in the form of methane, hydrogen, and potentially methanol. Formate is produced by either CoA-dependent cleavage of pyruvate or enzymatic reduction of CO2 in an NADH- or ferredoxin-dependent manner. Formate is consumed through oxidation to CO2 and H2 or can be further reduced via the Wood-Ljungdahl pathway for carbon fixation or industrially for the production of methanol. Here, we review the enzymes involved in the interconversion of formate and discuss potential applications for biofuels production.

Understanding the operational parameters affecting NDMA formation at Advanced Water Treatment Plants.

Science.gov (United States)

Farré, Maria José; Döderer, Katrin; Hearn, Laurence; Poussade, Yvan; Keller, Jurg; Gernjak, Wolfgang

2011-01-30

N-nitrosodimethylamine (NDMA) can be formed when secondary effluents are disinfected by chloramines. By means of bench scale experiments this paper investigates operational parameters than can help Advanced Water Treatment Plants (AWTPs) to reduce the formation of NDMA during the production of high quality recycled water. The formation of NDMA was monitored during a contact time of 24h using dimethylamine as NDMA model precursor and secondary effluent from wastewater treatment plants. The three chloramine disinfection strategies tested were pre-formed and in-line formed monochloramine, and pre-formed dichloramine. Although the latter is not employed on purpose in full-scale applications, it has been suggested as the main contributing chemical generating NDMA during chloramination. After 24h, the NDMA formation decreased in both matrices tested in the order: pre-formed dichloramine>in-line formed monochloramine≫pre-formed monochloramine. The most important parameter to consider for the inhibition of NDMA formation was the length of contact time between disinfectant and wastewater. Formation of NDMA was initially inhibited for up to 6h with concentrations consistently NDMA concentrations were reduced by a factor of 20 by optimizing the disinfection strategy. Copyright © 2010 Elsevier B.V. All rights reserved.

Effect of cold water injection on operation of and oil production from formations of Romashkino field

Energy Technology Data Exchange (ETDEWEB)

Mingareev, R Sh; Vakhitov, G G; Sultanov, S A

1968-11-01

Each year about 130 million cu m of cold water are injected into this field. Since cold water can lower reservoir temperature, increase oil viscosity, deposit paraffin in the formation, and reduce oil recovery, a thermal survey of this field was conducted. The survey showed that the average reservoir temperature was not reduced by cold-water injection for 15 yr. However, local cooling was observed at distances less than 400 m from the water injection well. Through these wells more than 4 PV of water have passed. The thermal front lags 1,500 m behind the advancing water front. For this reason, cold-water injection does not reduce oil recovery where there is uniform advance of the floodwater. When the formation is heterogeneous so that water advances more rapidly in high-permeability sand than in adjoining low-permeability sand, then the cooling effect can reduce oil recovery. For this reason, it is advisable to force water into the entire interval of the oil formation. An isotherm map of the Romashkino field is shown.

Isoporphyrin Intermediate in Heme Oxygenase Catalysis

Science.gov (United States)

Evans, John P.; Niemevz, Fernando; Buldain, Graciela; de Montellano, Paul Ortiz

2008-01-01

Human heme oxygenase-1 (hHO-1) catalyzes the O2- and NADPH-dependent oxidation of heme to biliverdin, CO, and free iron. The first step involves regiospecific insertion of an oxygen atom at the α-meso carbon by a ferric hydroperoxide and is predicted to proceed via an isoporphyrin π-cation intermediate. Here we report spectroscopic detection of a transient intermediate during oxidation by hHO-1 of α-meso-phenylheme-IX, α-meso-(p-methylphenyl)-mesoheme-III, and α-meso-(p-trifluoromethylphenyl)-mesoheme-III. In agreement with previous experiments (Wang, J., Niemevz, F., Lad, L., Huang, L., Alvarez, D. E., Buldain, G., Poulos, T. L., and Ortiz de Montellano, P. R. (2004) J. Biol. Chem. 279, 42593–42604), only the α-biliverdin isomer is produced with concomitant formation of the corresponding benzoic acid. The transient intermediate observed in the NADPH-P450 reductase-catalyzed reaction accumulated when the reaction was supported by H2O2 and exhibited the absorption maxima at 435 and 930 nm characteristic of an isoporphyrin. Product analysis by reversed phase high performance liquid chromatography and liquid chromatography electrospray ionization mass spectrometry of the product generated with H2O2 identified it as an isoporphyrin that, on quenching, decayed to benzoylbiliverdin. In the presence of H218O2, one labeled oxygen atom was incorporated into these products. The hHO-1-isoporphyrin complexes were found to have half-lives of 1.7 and 2.4 h for the p-trifluoromethyl- and p-methyl-substituted phenylhemes, respectively. The addition of NADPH-P450 reductase to the H2O2-generated hHO-1-isoporphyrin complex produced α-biliverdin, confirming its role as a reaction intermediate. Identification of an isoporphyrin intermediate in the catalytic sequence of hHO-1, the first such intermediate observed in hemoprotein catalysis, completes our understanding of the critical first step of heme oxidation. PMID:18487208

Water and Proppant Requirements and Water Production Associated with Undiscovered Petroleum in the Bakken and Three Forks Formations, North Dakota and Montana, USA

Science.gov (United States)

Haines, S. S.; Varela, B. A.; Thamke, J.; Hawkins, S. J.; Gianoutsos, N. J.; Tennyson, M. E.

2017-12-01

Water is used for several stages of oil and gas production, in particular for hydraulic fracturing that is typically used during production of petroleum from low-permeability shales and other rock types (referred to as "continuous" petroleum accumulations). Proppant, often sand, is also consumed during hydraulic fracturing. Water is then produced from the reservoir along with the oil and gas, representing either a disposal consideration or a possible source of water for further petroleum development or other purposes. The U.S. Geological Survey (USGS) has developed an approach for regional-scale estimation of these water and proppant quantities in order to provide an improved understanding of possible impacts and to help with planning and decision-making. Using the new methodology, the USGS has conducted a quantitative assessment of water and proppant requirements, and water production volumes, associated with associated with possible future production of undiscovered petroleum resources in the Bakken and Three Forks Formations, Williston Basin, USA. This water and proppant assessment builds directly from the 2013 USGS petroleum assessment for the Bakken and Three Forks Formations. USGS petroleum assessments incorporate all available geologic and petroleum production information, and include the definition of assessment units (AUs) that specify the geographic regions and geologic formations for the assessment. The 2013 petroleum assessment included 5 continuous AUs for the Bakken Formation and one continuous AU for the Three Forks Formation. The assessment inputs are defined probabilistically, and a Monte Carlo approach provides outputs that include uncertainty bounds. We can summarize the assessment outputs with the mean values of the associated distributions. The mean estimated total volume of water for well drilling and cement for all six continuous AUs is 5.9 billion gallons, and the mean estimated volume of water for hydraulic fracturing for all AUs is 164

Formation of adenosine 5'-tetraphosphate from the acyl phosphate intermediate: a difference between the MurC and MurD synthetases of Escherichia coli.

Science.gov (United States)

Bouhss, A; Dementin, S; van Heijenoort, J; Parquet, C; Blanot, D

1999-06-18

The mechanism of the Mur synthetases of peptidoglycan biosynthesis is thought to involve in each case the successive formation of an acyl phosphate and a tetrahedral intermediate. The existence of the acyl phosphates for the MurC and MurD enzymes from Escherichia coli was firmly established by their in situ reduction by sodium borohydride followed by acid hydrolysis, yielding the corresponding amino alcohols. Furthermore, it was found that MurD, but not MurC, catalyses the synthesis of adenosine 5'-tetraphosphate from the acyl phosphate, thereby substantiating its existence and pointing out a difference between the two enzymes.

Detecting Elusive Intermediates in Carbohydrate Conversion: A Dynamic Ensemble of Acyclic Glucose-Catalyst Complexes

DEFF Research Database (Denmark)

Meier, Sebastian; Karlsson, Magnus; Jensen, Pernille Rose

2017-01-01

within few seconds prior to reaching a steady state. Exchange between the acyclic intermediates increases at conditions that favor epimerization. Species accounting for less than 0.05% of total glucose can be monitored with sub-second time resolution to allow kinetic analysis of intermediate formation...... and catalytic conversion. Epimerization occurs 2-3 orders of magnitude-fold faster than the binding of acyclic glucose to the catalyst at near-optimum reaction conditions. The current study brings insight in to the nature of acyclic intermediate-catalyst complexes of very low population and into experimental...... strategies for characterizing very minor intermediates in carbohydrate conversion to value-added compounds....

Isotopically sensitive branching in the formation of cyclic monoterpenes: proof that (-)-alpha-pinene and (-)-beta-pinene are synthesized by the same monoterpene cyclase via deprotonation of a common intermediate

International Nuclear Information System (INIS)

Croteau, R.B.; Wheeler, C.J.; Cane, D.E.; Ebert, R.; Ha, H.J.

1987-01-01

To determine whether the bicyclic monoterpene olefins (-)-alpha-pinene and (-)-beta-pinene arise biosynthetically from the same monoterpene cyclase by alternate deprotonations of a common carbocationic intermediate, the product distributions arising from the acyclic precursor [10- 2 H 3 ,1- 3 H]geranyl pyrophosphate were compared with those resulting from incubation of [1-3H]geranyl pyrophosphate with (-)-pinene cyclase from Salvia officinalis. Alteration in proportions of the olefinic products generated by the partially purified pinene cyclase resulted from the suppression of the formation of (-)-beta-pinene (C10 deprotonation) by a primary deuterium isotope effect with a compensating stimulation of the formation of (-)-alpha-pinene (C4 deprotonation). (-)-Pinene cyclase as well as (+)-pinene cyclase also exhibited a decrease in the proportion of the acyclic olefin myrcene generated from the deuteriated substrate, accompanied by a corresponding increase in the commitment to cyclized products. The observation of isotopically sensitive branching, in conjunction with quantitation of the magnitude of the secondary deuterium isotope effect on the overall rate of product formation by the (+)- and (-)-pinene cyclases as well as two other monoterpene cyclases from the same tissue, supports the biosynthetic origin of (-)-alpha-pinene and (-)-beta-pinene by alternative deprotonations of a common enzymatic intermediate. A biogenetic scheme consistent with these results is presented, and alternate proposals for the origin of the pinenes are addressed

Adsorption of water and carbon dioxide on hematite and consequences for possible hydrate formation.

Science.gov (United States)

Kvamme, Bjørn; Kuznetsova, Tatiana; Kivelae, Pilvi-Helina

2012-04-07

The interest in carbon dioxide for enhanced oil recovery is increasing proportional to the decline in naturally driven oil production and also due to the increasing demand for reduced emission of carbon dioxide into the atmosphere. Transport of carbon dioxide in offshore pipelines involves high pressure and low temperatures, conditions which may lead to formation of hydrates from residual water dissolved in carbon dioxide and carbon dioxide. The critical question is whether the water at certain temperatures and pressures will drop out as liquid droplets first, and then form hydrates, or alternatively, adsorb on the pipeline surfaces, and subsequently form hydrates heterogeneously. In this work, we used several different basis sets of density functional theory in ab initio calculations to estimate the charge distribution of hematite (the dominating component of rust) crystals. These rust particles were embedded in water and chemical potential for adsorbed water molecules was estimated through thermodynamic integration and compared to similar estimates for water clusters of the same size. While the generated charges were not unique, the use of high order approximations and different basis sets provides a range of likely charge distributions. Values obtained for the chemical potential of water in different surroundings indicated that it would be thermodynamically favorable for water to adsorb on hematite, and that evaluation of potential carbon dioxide hydrate formation conditions and kinetics should be based on this formation mechanism. Depending on the basis set and approximations, the estimated gain for water to adsorb on the hematite surface rather than condense as droplets varied between -1.7 kJ mole(-1) and -3.4 kJ mole(-1). The partial charge distribution on the hematite surface is incompatible with the hydrate structure, and thus hydrates will be unable to attach to the surface. The behavior of water outside the immediate vicinity of hematite (beyond 3

Formation and occurrence of new polar iodinated disinfection byproducts in drinking water.

Science.gov (United States)

Pan, Yang; Li, Wenbin; An, Hao; Cui, Hao; Wang, Ying

2016-02-01

During drinking water disinfection, iodinated disinfection byproducts (I-DBPs) can be generated through reactions between iodide, disinfectants, and natural organic matter. Drinking water I-DBPs have been increasingly attracting attention as emerging organic pollutants as a result of their significantly higher toxicity and growth inhibition than their chloro- and bromo-analogues. In this study, by adopting ultra performance liquid chromatography/electrospray ionization-triple quadrupole mass spectrometry precursor ion scan, multiple reaction monitoring, and product ion scan analyses, 11 new polar I-DBPs with confirmed structures and eight new polar I-DBPs with proposed structures were detected in simulated drinking water samples. Chloramination of simulated raw waters containing natural organic matter with higher aromaticity produced higher levels of new phenolic I-DBPs. Formation of new polar I-DBPs and total organic iodine (TOI) was most favored in chloramination, followed by chlorine dioxide treatment, and relatively minor in chlorination. Lower pH in chloramination substantially enhanced the formation of new polar I-DBPs and TOI. NH2Cl and dissolved organic nitrogen could be important nitrogen sources and precursors for formation of the two new nitrogenous phenolic I-DBPs. Notably, in tap water samples collected from nine major cities located in the Yangtze River Delta region of China, seven of the 11 new polar I-DBPs with confirmed structures were detected at levels from 0.11 to 28 ng/L, and the two new nitrogenous phenolic I-DBPs were ubiquitous with concentrations from 0.12 to 24 ng/L, likely due to the relatively high dissolved organic nitrogen levels in regional source waters. Copyright © 2015 Elsevier Ltd. All rights reserved.

Biofilm formation and control in a simulated spacecraft water system - Interim results

Science.gov (United States)

Schultz, John R.; Taylor, Robert D.; Flanagan, David T.; Gibbons, Randall E.; Brown, Harlan D.; Sauer, Richard L.

1989-01-01

The ability of iodine to control microbial contamination and biofilm formation in spacecraft water distribution systems is studied using two stainless steel water subsystems. One subsystem has an iodine level of 2.5 mg/L maintained by an iodinated ion-exchange resin. The other subsystem has no iodine added. Stainless steel coupons are removed from each system to monitor biofilm formation. Results from the first six months of operation indicate that 2.5 mg/L of iodine has limited the number of viable bacteria that can be recovered from the iodinated subsystem. Epifluorescence microscopy of the coupons taken from this subsystem, however, indicates some evidence of microbial colonization after 15 weeks of operation. Numerous bacteria have been continually removed from both the water samples and the coupons taken from the noniodinated subsystem after only 3 weeks of operation.

Influence of the level of subsoil water on the distribution of moisture content in a peat formation

Energy Technology Data Exchange (ETDEWEB)

Fedotov, A.I.; Kostyuk, N.S.

1983-01-01

Under laboratory and field conditions, observations are made of the influence of the level of subsoil water on the distribution of moisture content in the upper layers of the peat formation. It is established that prolonged evaporation sharply reduces the moisture content of the upper layers of the formation at a depth up to 20cm. Precipitation is mainly absorbed by the upper layers of the formation and can penetrate in the season with level of subsoil water about 1m at depth of no more than 50cm. The zone of complete capillary water-saturation of the upper formation does not exceed 45cm.

X-irradiation affects all DNA replication intermediates when inhibiting replication initiation

International Nuclear Information System (INIS)

Loenn, U.; Karolinska Hospital, Stockholm

1982-01-01

When a human melanoma line was irradiated with 10 Gy, there was, after 30 to 60 min, a gradual reduction in the DNA replication rate. Ten to twelve hours after the irradiation, the DNA replication had returned to near normal rate. The results showed tht low dose-rate X-irradiation inhibits preferentially the formation of small DNA replication intermediates. There is no difference between the inhibition of these replication intermediates formed only in the irradiated cells and those formed also in untreated cells. (U.K.)

Formation and spreading of Arabian Sea high-salinity water mass

Digital Repository Service at National Institute of Oceanography (India)

PrasannaKumar, S.; Prasad, T.G.

The formation and seasonal spreading of the Arabian Sea High-Salinity Water (ASHSW) mass were studied based on the monthly mean climatology of temperature and salinity in the Arabian Sea, north of the equator and west of 80 degrees E, on a 2 degrees...

Effects of ancient porosity and permeability on formation of sedimentary dolomites: Devonian Jefferson Formation (Frasnian), south-central Montana

Energy Technology Data Exchange (ETDEWEB)

Smith, T.M.; Dorobek, S.L.

1987-08-01

Petrographic and geochemical evidence indicates that multiple dolomitization and dolomite stabilization events affected the Devonian Jefferson Formation (Frasnian) in south-central Montana. Several types of dolomite occur, defined by cathodoluminescence: nonzoned, dully luminescent subhedral-anhedral mosaics (most common), euhedral nonzoned and zoned dolomites, zoned dolomite cements, and irregularly luminescent dolomites (dully luminescent with irregularly luminescent regions). The irregularly luminescent fabrics probably represent partial replacement of early dolomite phases with later dolomite phases. Nonzoned, Ca-enriched, euhedral dolomites occur in calcite-cemented, coarse-grained limestone layers. These permeable layers probably were conduits for early meteoric waters, that occluded porosity in the limestones and prevented later dolomite stabilization. Irregularly luminescent dolomites are interpreted as intermediate fabrics in the dolomite stabilization process. Later calcite cements which occlude intercrystalline porosity prevented further dolomite replacement. Total recrystallization of remaining dolomites and formation of final dully luminescent mosaics occurred prior to brecciation and stylolitization.

N-Nitrosodimethylamine (NDMA) and its precursors in water and wastewater: A review on formation and removal.

Science.gov (United States)

Sgroi, Massimiliano; Vagliasindi, Federico G A; Snyder, Shane A; Roccaro, Paolo

2018-01-01

This review summarizes major findings over the last decade related to N-Nitrosodimethylamine (NDMA) in water and wastewater. In particular, the review is focused on the removal of NDMA and of its precursors by conventional and advanced water and wastewater treatment processes. New information regarding formation mechanisms and precursors are discussed as well. NDMA precursors are generally of anthropogenic origin and their main source in water have been recognized to be wastewater discharges. Chloramination is the most common process that results in formation of NDMA during water and wastewater treatment. However, ozonation of wastewater or highly contaminated surface water can also generate significant levels of NDMA. Thus, NDMA formation control and remediation has become of increasing interest, particularly during treatment of wastewater-impacted water and during potable reuse application. NDMA formation has also been associated with the use of quaternary amine-based coagulants and anion exchange resins. UV photolysis with UV fluence far higher than typical disinfection doses is generally considered the most efficient technology for NDMA mitigation. However, recent studies on the optimization of biological processes offer a potentially lower-energy solution. Options for NDMA control include attenuation of precursor materials through physical removal, biological treatment, and/or deactivation by application of oxidants. Nevertheless, NDMA precursor identification and removal can be challenging and additional research and optimization is needed. As municipal wastewater becomes increasingly used as a source water for drinking, NDMA formation and mitigation strategies will become increasingly more important. The following review provides a summary of the most recent information available. Copyright © 2017 Elsevier Ltd. All rights reserved.

Intermediate-energy neutron beam for NCT at MURR

International Nuclear Information System (INIS)

Brugger, R.M.; Less, T.J.; Passmore, G.G.

1986-01-01

The University of Missouri Research Reactor (MURR) is one of the high-flux reactors in the USA and it can be used to produce an intense beam of intermediate-energy neutrons for neutron capture therapy. Two methods are being evaluated at MURR to produce such a beam. The first uses a moderator of Al 2 O 3 replacing part of the graphite and water on one side of the core of the reactor to produce a source of predominantly intermediate-energy neutrons. The second method is a filter of 238 U between the core and the patient position to pass only intermediate-energy neutrons. The results of these evaluations are presented in this paper along with an outline of the other resources at the University of Missouri-Columbia that are available to support an NCT program. 4 references, 7 figures, 1 table

Electron driven water formation from oxyhydrogen clusters in superfluid helium nanodroplets

International Nuclear Information System (INIS)

Renzler, Michael; Kranabetter, Lorenz; Barwa, Erik; Scheier, Paul; Illenberger, Eugen

2015-01-01

Helium nanodroplets provide an enviroment that allow studies of chemical reactions at ultracold temperatures. We use these droplets as a matrix to study the formation of water upon electron bombardment of oxyhydrogen clusters (paper)

Degradation of amine-based water treatment polymers during chloramination as N-nitrosodimethylamine (NDMA) precursors.

Science.gov (United States)

Park, Sang-Hyuck; Wei, Shuting; Mizaikoff, Boris; Taylor, Amelia E; Favero, Cedrick; Huang, Ching-Hua

2009-03-01

Recent studies indicated that water treatment polymers such as poly(epichlorohydrin dimethylamine) (polyamine) and poly(diallyldimethylammonium chloride) (polyDADMAC) may form N-nitrosodimethylamine (NDMA) when in contact with chloramine water disinfectants. To minimize such potential risk and improve the polymer products, the mechanisms of how the polymers behave as NDMA precursors need to be elucidated. Direct chloramination of polymers and intermediate monomers in reagent water was conducted to probe the predominant mechanisms. The impact of polymer properties including polymer purity, polymer molecular weight and structure, residual dimethylamine (DMA), and other intermediate compounds involved in polymer synthesis, and reaction conditions such as pH, oxidant dose, and contact time on the NDMA formation potential (NDMA-FP) was investigated. Polymer degradation after reaction with chloramines was monitored at the molecular level using FT-IR and Raman spectroscopy. Overall, polyamines have greater NDMA-FP than polyDADMAC, and the NDMA formation from both polymers is strongly related to polymer degradation and DMA release during chloramination. Polyamines' tertiary amine chain ends play a major role in their NDMA-FP, while polyDADMACs' NDMA-FP is related to degradation of the quaternary ammonium ring group.

Exploring the Role of Carbonate in the Formation of an Organomanganese Tetramer.

Science.gov (United States)

Kadassery, Karthika J; Dey, Suman Kr; Friedman, Alan E; Lacy, David C

2017-08-07

The formation of metal-oxygen clusters is an important chemical transformation in biology and catalysis. For example, the biosynthesis of the oxygen-evolving complex in the enzyme photosystem II is a complicated stepwise process that assembles a catalytically active cluster. Herein we describe the role that carbonato ligands have in the formation of the known tetrameric complex [Mn(CO) 3 (μ 3 -OH)] 4 (1). Complex 1 is synthesized in one step via the treatment of Mn 2 (CO) 10 with excess Me 3 NO·2H 2 O. Alternatively, when anhydrous Me 3 NO is used, an OH-free synthetic intermediate (2) with carbonato ligands is produced. Complex 2 produces carbon dioxide, Me 3 NO·2H 2 O, and 1 when treated with water. Labeling studies reveal that the μ 3 -OH ligands in 1 are derived from the water and possibly the carbonato ligands in 2.

Influential factors of formation kinetics of flocs produced by water treatment coagulants.

Science.gov (United States)

Wu, Chunde; Wang, Lin; Hu, Bing; Ye, Jian

2013-05-01

The growth rate and size of floc formation is of great importance in water treatment especially in coagulation process. The floc formation kinetics and the coagulation efficiency of synthetic water were investigated by using an on-line continuous optical photometric dispersion analyze and the analysis of water quality. Experimental conditions such as alum dosage, pH value for coagulation, stirring intensity and initial turbidity were extensively examined. The photometric dispersion analyze results showed that coagulation of kaolin suspensions with two coagulants (alum and polyaluminium chloride) could be taken as a two-phase process: slow and rapid growth periods. Operating conditions with higher coagulant doses, appropriate pH and average shear rate might be particularly advantageous. The rate of overall floc growth was mainly determined by a combination of hydraulic and water quality conditions such as pH and turbidity. The measurement of zeta potential indicates that polyaluminium chloride exhibited higher charge-neutralizing ability than alum and achieved lower turbidities than alum for equivalent Al dosages. Under the same operating conditions, the alum showed a higher grow rate, but with smaller floc size.

Reaction Mechanisms for the Electrochemical Reduction of CO2 to CO and Formate on the Cu(100) Surface at 298K from Quantum Mechanics Free Energy Calculations with Explicit Water.

Science.gov (United States)

Cheng, Tao; Xiao, Hai; Goddard, William A

2016-10-11

Copper is the only elemental metal that reduces a significant fraction of CO 2 to hydrocarbons and alcohols, but the atomistic reaction mechanism that controls the product distributions are not known because it has not been possible to detect the reaction intermediates on the electrode surface experimentally, or carry out Quantum Mechanics (QM) calculations with a realistic description of the electrolyte (water). Here, we carry out Quantum Mechanics (QM) calculations with an explicit description of water on the Cu(100) surface (experimentally shown to be stable under CO2RR conditions) to examine the initial reaction pathways to form CO and formate (HCOO - ) from CO 2 through free energy calculations at 298K and pH 7. We find that CO formation proceeds from physisorbed CO 2 to chemisorbed CO 2 (*CO 2 δ- ), with a free energy barrier of ΔG ‡ =0.43 eV, the rate determining step (RDS). The subsequent barriers of protonating *CO 2 δ- to form COOH* and then dissociating COOH* to form *CO are 0.37 eV and 0.30 eV, respectively. HCOO - formation proceeds through a very different pathway in which physisorbed CO 2 reacts directly with a surface H* (along with electron transfer), leading to ΔG ‡ = 0.80 eV. Thus, the competition between CO formation and HCOO - formation occurs in the first electron transfer step. On Cu(100), the RDS for CO formation is lower, making CO the predominant product. Thus, to alter the product distribution we need to control this first step of CO 2 binding, which might involve alloying or changing the structure at the nanoscale.

A Multiwavelength Approach to the Star Formation Rate Estimation in Galaxies at Intermediate Redshifts

Science.gov (United States)

Cardiel, N.; Elbaz, D.; Schiavon, R. P.; Willmer, C. N. A.; Koo, D. C.; Phillips, A. C.; Gallego, J.

2003-02-01

We use a sample of seven starburst galaxies at intermediate redshifts (z~0.4 and 0.8) with observations ranging from the observed ultraviolet to 1.4 GHz, to compare the star formation rate (SFR) estimators that are used in the different wavelength regimes. We find that extinction-corrected Hα underestimates the SFR, and the degree of this underestimation increases with the infrared luminosity of the galaxies. Galaxies with very different levels of dust extinction as measured with SFRIR/SFR(Hα, uncorrected for extinction) present a similar attenuation A[Hα], as if the Balmer lines probed a different region of the galaxy than the one responsible for the bulk of the IR luminosity for large SFRs. In addition, SFR estimates derived from [O II] λ3727 match very well those inferred from Hα after applying the metallicity correction derived from local galaxies. SFRs estimated from the UV luminosities show a dichotomic behavior, similar to that previously reported by other authors in galaxies at zfinancial support of the W. M. Keck Foundation. Based in part on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. Based in part on observations with the Infrared Space Observatory (ISO), an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, Netherlands, and United Kingdom) with the participation of ISAS and NASA.

Fingerprinting taste buds: intermediate filaments and their implication for taste bud formation.

OpenAIRE

Witt, M; Reutter, K; Ganchrow, D; Ganchrow, J R

2000-01-01

Intermediate filaments in taste organs of terrestrial (human and chick) as well as aquatic (Xenopus laevis) species were detected using immunohistochemistry and electron microscopy. During development, the potential importance of the interface between the taste bud primordium and non-gustatory adjacent tissues is evidenced by the distinct immunoreactivity of a subpopulation of taste bud cells for cytokeratins and vimentin. In human foetuses, the selective molecular marker for taste bud primor...

Determination of geochemical characters of insterstitial waters of pleistocene Italian clay formations

International Nuclear Information System (INIS)

Fontanive, A.; Gragnani, R.; Mignuzzi, C.; Spat, G.

1985-01-01

The geochemical characters of clay formations and of their pore water are fundamental with regards to the mobility of the radionuclides as well as to the corrosion processes on enginered barriers. Experimental researches have been carried out in different types of clay, which represent Italian formations, for the characterization of pore water. A squeezer system, which reaches 1500 Kg/cm 2 in pressure, and an analytical micro-scale methodology, for the determination of dissolved constituents in pore water, were set up. The extracted pore water ranges from 60% to 85% in relation to consolidation state of clay. The chemical composition of the extracted fluid has been checked during the squeezing. During this step the observed variations were smaller than those between the different specimens of the same sample. The comparison between the results obtained by squeezing and by a multiple washing technique, using increasing water/sediment ratios, shows that the last one does not give reliable results on the chemical composition of pore water. This is due to the presence of easily weatherable minerals and to the exchange processes between the clayey minerals and the solution. Nevertheless both these techniques have supplied complementary information about geochemical processes in water-rock interaction. The salinity of pore water ranges from 0.45 g/l to 24.5 g/l and the chemism always shows a high content of calcium-magnesium sulfate, or sodium chloride or calcium-magnesium-sulfate with sodium chloride. The correlation between geochemical composition of pore water and mineralogical composition of clay is not significant

Carbon Disulfide (CS2) Mechanisms in Formation of Atmospheric Carbon Dioxide (CO2) Formation from Unconventional Shale Gas Extraction and Processing Operations and Global Climate Change.

Science.gov (United States)

Rich, Alisa L; Patel, Jay T

2015-01-01

Carbon disulfide (CS2) has been historically associated with the production of rayon, cellophane, and carbon tetrachloride. This study identifies multiple mechanisms by which CS2 contributes to the formation of CO2 in the atmosphere. CS2 and other associated sulfide compounds were found by this study to be present in emissions from unconventional shale gas extraction and processing (E&P) operations. The breakdown products of CS2; carbonyl sulfide (COS), carbon monoxide (CO), and sulfur dioxide (SO2) are indirect greenhouse gases (GHGs) that contribute to CO2 levels in the atmosphere. The heat-trapping nature of CO2 has been found to increase the surface temperature, resulting in regional and global climate change. The purpose of this study is to identify five mechanisms by which CS2 and the breakdown products of CS2 contribute to atmospheric concentrations of CO2. The five mechanisms of CO2 formation are as follows: Chemical Interaction of CS2 and hydrogen sulfide (H2S) present in natural gas at high temperatures, resulting in CO2 formation;Combustion of CS2 in the presence of oxygen producing SO2 and CO2;Photolysis of CS2 leading to the formation of COS, CO, and SO2, which are indirect contributors to CO2 formation;One-step hydrolysis of CS2, producing reactive intermediates and ultimately forming H2S and CO2;Two-step hydrolysis of CS2 forming the reactive COS intermediate that reacts with an additional water molecule, ultimately forming H2S and CO2. CS2 and COS additionally are implicated in the formation of SO2 in the stratosphere and/or troposphere. SO2 is an indirect contributor to CO2 formation and is implicated in global climate change.

Intermediate tree cover can maximize groundwater recharge in the seasonally dry tropics

Science.gov (United States)

Ilstedt, U.; Bargués Tobella, A.; Bazié, H. R.; Bayala, J.; Verbeeten, E.; Nyberg, G.; Sanou, J.; Benegas, L.; Murdiyarso, D.; Laudon, H.; Sheil, D.; Malmer, A.

2016-01-01

Water scarcity contributes to the poverty of around one-third of the world’s people. Despite many benefits, tree planting in dry regions is often discouraged by concerns that trees reduce water availability. Yet relevant studies from the tropics are scarce, and the impacts of intermediate tree cover remain unexplored. We developed and tested an optimum tree cover theory in which groundwater recharge is maximized at an intermediate tree density. Below this optimal tree density the benefits from any additional trees on water percolation exceed their extra water use, leading to increased groundwater recharge, while above the optimum the opposite occurs. Our results, based on groundwater budgets calibrated with measurements of drainage and transpiration in a cultivated woodland in West Africa, demonstrate that groundwater recharge was maximised at intermediate tree densities. In contrast to the prevailing view, we therefore find that moderate tree cover can increase groundwater recharge, and that tree planting and various tree management options can improve groundwater resources. We evaluate the necessary conditions for these results to hold and suggest that they are likely to be common in the seasonally dry tropics, offering potential for widespread tree establishment and increased benefits for hundreds of millions of people. PMID:26908158

Phase formation in contact of dissimilar metals

Energy Technology Data Exchange (ETDEWEB)

Savvin, V S; Kazachkova, Yu A; Povzner, A A [Ural State Technical University-UPI, Mira st., 19, A-203, Yekaterinburg 620002 (Russian Federation)], E-mail: savvin-vs@yandex.ru

2008-02-15

Formation and growth of intermediate phases in contact of the crystalline samples forming a two-component eutectic system is considered. It is shown that during the competition to a growing liquid phase the intermediate solid phases cannot grow by diffusion. The alternative is formation of metastable areas of a liquid phase. Measurements of liquid layers extent in Pb-Bi and In-Bi systems have allowed to define the composition of liquid on interface where formation of metastable liquid is possible. The results show that the concentration interval of a liquid layer corresponds to a stable constitution diagram. In order to explain the experimental results the hypothesis according to which the intermediate solid phases are formed as a result of precipitation from metastable melt is considered. The experimental confirmation of formation and crystallization of a metastable liquid is the fact that intergrowth of the samples forming system with an intermetallic phase at temperatures below the temperature of fusion of the most low-melting eutectic is observed. The possibility of the processes concerned with the occurrence of metastable areas of a liquid is showed by means of computer imitation.

Comparison between HPSEC-OCD and F-EEMs for assessing DBPs formation in water.

Science.gov (United States)

Hidayah, Euis Nurul; Chou, Yung-Chen; Yeh, Hsuan-Hsien

2017-03-21

In this study, natural organic matter (NOM) in source water, as well as the treated water after coagulation with or without potassium permanganate (KMnO 4 ) preoxidation, was characterized by using high performance size exclusion chromatography with organic carbon detector (HPSEC-OCD) and fluorescence excitation emission matrices (F-EEMs) with parallel factor (PARAFAC) analysis. Bulk parameters, such as dissolved organic carbon (DOC) and ultraviolet light absorbance at 254 nm (UV 254 ), were also analyzed. The results show that KMnO 4 preoxidation caused the breakdown of high molecular weight (MW) organics into low MW organics. All organics, whether those that existed in the source water or those generated by KMnO 4 preoxidation, could be partly removed by coagulation. Combining the derived organic fractions obtained from HPSEC-OCD with peak-fitting and from F-EEMs with PARAFAC on the same sample, humic substances have been specified as the main organic composition. Further, the predictive models for trihalomethanes formation potential (THMFP) and haloacetic acids formation potential (HAAFP) based on organic fractions from HPSEC-OCD have higher accuracy than those based on the components from PARAFAC modeling. These models provide useful tools to specify the organic fractions from HPSEC-OCD and F-EEMs that constitute active precursors towards trihalomethanes (THMs) or haloacetic acids (HAAs) formation in water. Further, by knowing the major organic precursors, it would facilitate choosing the appropriate water treatment process for disinfection by-products (DBPs) control.

INTERMEDIATE STAGES OF REACTIONS FORMING CARBIDES OF TITANIUM, ZIRCONIUM, VANADIUM, NIOBIUM, AND TANTALIUM

Science.gov (United States)

intermediate and final products, and also during the calculation of approximate heat values of their formation, the passage of the reaction is confirmed...for obtaining TiC, and ZrC through the stage of intermediate oxides Ti2O3, Ti3O5, TiO and Zr2O3, ZrO, respectively and also for the reaction of...forming carbides of V (from V2O3 + 5C), of Nb and Ta (from Nb2O5 + 7C and Ta205 + 7C) through the stage of intermediate oxides VO, V4O and TaO2, Ta4O. The

Effect of temperature during wood torrefaction on the formation of lignin liquid intermediates

Science.gov (United States)

Manuel Raul Pelaez-Samaniego; Vikram Yadama; Manuel Garcia-Perez; Eini Lowell; Armando G. McDonald

2014-01-01

Torrefaction enhances physical properties of lignocellulosic biomass and improves its grindability. Energy densification, via fuel pellets production, is one of the most promising uses of torrefaction. Lignin contributes to self-bonding of wood particles during pelletization. In biomass thermal pretreatment, part oflignin (in the form of lignin liquid intermediates –...

Formation of metal-F bonds during frictional sliding : Influence of water and applied load

NARCIS (Netherlands)

Shen, J. T.; Pei, Y. T.; De Hosson, J. Th. M.

2016-01-01

Effects of water lubrication and applied load on the formation of PTFE transfer films and metal-F bonds during sliding when PTFE filled composites sliding against steel and Al2O3 are investigated. In water lubricated conditions, XPS analysis reveals that a thin layer of water molecules at the

Unraveling the structure and chemical mechanisms of highly oxygenated intermediates in oxidation of organic compounds

KAUST Repository

Wang, Zhandong

2017-11-28

Decades of research on the autooxidation of organic compounds have provided fundamental and practical insights into these processes; however, the structure of many key autooxidation intermediates and the reactions leading to their formation still remain unclear. This work provides additional experimental evidence that highly oxygenated intermediates with one or more hydroperoxy groups are prevalent in the autooxidation of various oxygenated (e.g., alcohol, aldehyde, keto compounds, ether, and ester) and nonoxygenated (e.g., normal alkane, branched alkane, and cycloalkane) organic compounds. These findings improve our understanding of autooxidation reaction mechanisms that are routinely used to predict fuel ignition and oxidative stability of liquid hydrocarbons, while also providing insights relevant to the formation mechanisms of tropospheric aerosol building blocks. The direct observation of highly oxygenated intermediates for the autooxidation of alkanes at 500–600 K builds upon prior observations made in atmospheric conditions for the autooxidation of terpenes and other unsaturated hydrocarbons; it shows that highly oxygenated intermediates are stable at conditions above room temperature. These results further reveal that highly oxygenated intermediates are not only accessible by chemical activation but also by thermal activation. Theoretical calculations on H-atom migration reactions are presented to rationalize the relationship between the organic compound’s molecular structure (n-alkane, branched alkane, and cycloalkane) and its propensity to produce highly oxygenated intermediates via extensive autooxidation of hydroperoxyalkylperoxy radicals. Finally, detailed chemical kinetic simulations demonstrate the influence of these additional reaction pathways on the ignition of practical fuels.

Unraveling the structure and chemical mechanisms of highly oxygenated intermediates in oxidation of organic compounds

KAUST Repository

Wang, Zhandong; Popolan-Vaida, Denisia M.; Chen, Bingjie; Moshammer, Kai; Mohamed, Samah; Wang, Heng; Sioud, Salim; Raji, Misjudeen; Kohse-Hö inghaus, Katharina; Hansen, Nils; Dagaut, Philippe; Leone, Stephen R.; Sarathy, Mani

2017-01-01

Decades of research on the autooxidation of organic compounds have provided fundamental and practical insights into these processes; however, the structure of many key autooxidation intermediates and the reactions leading to their formation still remain unclear. This work provides additional experimental evidence that highly oxygenated intermediates with one or more hydroperoxy groups are prevalent in the autooxidation of various oxygenated (e.g., alcohol, aldehyde, keto compounds, ether, and ester) and nonoxygenated (e.g., normal alkane, branched alkane, and cycloalkane) organic compounds. These findings improve our understanding of autooxidation reaction mechanisms that are routinely used to predict fuel ignition and oxidative stability of liquid hydrocarbons, while also providing insights relevant to the formation mechanisms of tropospheric aerosol building blocks. The direct observation of highly oxygenated intermediates for the autooxidation of alkanes at 500–600 K builds upon prior observations made in atmospheric conditions for the autooxidation of terpenes and other unsaturated hydrocarbons; it shows that highly oxygenated intermediates are stable at conditions above room temperature. These results further reveal that highly oxygenated intermediates are not only accessible by chemical activation but also by thermal activation. Theoretical calculations on H-atom migration reactions are presented to rationalize the relationship between the organic compound’s molecular structure (n-alkane, branched alkane, and cycloalkane) and its propensity to produce highly oxygenated intermediates via extensive autooxidation of hydroperoxyalkylperoxy radicals. Finally, detailed chemical kinetic simulations demonstrate the influence of these additional reaction pathways on the ignition of practical fuels.

Low temperature intermediate band metallic behavior in Ti implanted Si

Energy Technology Data Exchange (ETDEWEB)

Olea, Javier, E-mail: oleaariza@fis.ucm.es; Pastor, David; Garcia-Hemme, Eric; Garcia-Hernansanz, Rodrigo; Prado, Alvaro del; Martil, Ignacio; Gonzalez-Diaz, German

2012-08-31

Si samples implanted with very high Ti doses and subjected to Pulsed-Laser Melting (PLM) have been electrically analyzed in the scope of a two-layer model previously reported based on the Intermediate Band (IB) theory. Conductivity and Hall effect measurements using the van der Pauw technique suggest that the insulator-metal transition takes place for implantation doses in the 10{sup 14}-10{sup 16} cm{sup -2} range. Results of the sample implanted with the 10{sup 16} cm{sup -2} dose show a metallic behavior at low temperature that is explained by the formation of a p-type IB out of the Ti deep levels. This suggests that the IB would be semi-filled, which is essential for IB photovoltaic devices. - Highlights: Black-Right-Pointing-Pointer We fabricated high dose Ti implanted Si samples for intermediate band research. Black-Right-Pointing-Pointer We measured the electronic transport properties in the 7-300 K range. Black-Right-Pointing-Pointer We show an insulator to metallic transition when the intermediate band is formed. Black-Right-Pointing-Pointer The intermediate band is semi-filled and populated by holes. Black-Right-Pointing-Pointer We satisfactorily explain the electrical behavior by an intermediate band model.

Nano-silver in drinking water and drinking water sources: stability and influences on disinfection by-product formation.

Science.gov (United States)

Tugulea, A-M; Bérubé, D; Giddings, M; Lemieux, F; Hnatiw, J; Priem, J; Avramescu, M-L

2014-10-01

untreated Ottawa River water, with a dissolved organic carbon concentration of 6 mg/L, was significantly higher than the stability of the nano-silver dispersions in distilled, organic-free water. Nano-silver particles suspended in the groundwater agglomerated and were quickly and quantitatively removed from the solution. Our data confirm previous observations that natural dissolved organic matter stabilizes nano-silver particles, while the high-ionic strength of groundwater appears to favor their agglomeration and precipitation. As expected, nano-silver was not stable in Ottawa River water through the chlorination process, but survived for many days when added to the Ottawa River water after treatment with chlorine or chloramines. Stirring appeared to have minimal effect on nano-silver stability in untreated and treated Ottawa River water. The profile of DBPs formed in the presence of nAg differed significantly from the profile of DBPs formed in the absence of nAg only at the 1 mg/L nAg concentration. The differences observed consisted mainly in reduced formation of some brominated DBPs and a small increase in the formation of cyanogen chloride. The reduced formation of brominated congeners may be explained by the decrease in available bromide due to the presence of Ag(+) ions. It should be noted that a concentration of 1 mg/L is significantly higher than nAg concentrations that would be expected to be present in surface waters, but these results could be significant for the disinfection of some wastewaters with comparably high nano-silver concentrations.

Intermediate Energy Activation File (IEAF-99)

International Nuclear Information System (INIS)

Korovin, Yu.; Konobeev, A.; Pereslavtsev, P.; Stankovskij, A.; Fischer, U.; Moellendorff, U. von

1999-01-01

Nuclear data library IEAF-99, elaborated to study processes of interactions of intermediate energy neutrons with materials in accelerator driven systems, is described. The library is intended for activation and transmutation studies for materials irradiated by neutrons. IEAF-99 contains evaluated neutron induced reaction cross sections at the energies 0-150 MeV for 665 stable and unstable nuclei from C to Po. Approximately 50,000 excitation functions are included in the library. The IEAF-99 data are written in the ENDF-6 format combining MF = 3,6 MT = 5 data recording. (author)

The Niobrara Formation as a challenge to water quality in the Arkansas River, Colorado, USA

Science.gov (United States)

Bern, Carleton R.; Stogner, Sr., Robert W.

2017-01-01

Study regionArkansas River, east of the Rocky Mountains.Study focusCretaceous sedimentary rocks in the western United States generally pose challenges to water quality, often through mobilization of salts and trace metals by irrigation. However, in the Arkansas River Basin of Colorado, patchy exposure of multiple Cretaceous formations has made it difficult to identify which formations are most problematic. This paper examines water quality in surface-water inflows along a 26-km reach of the Arkansas River relative to the presence or absence of the Cretaceous Niobrara Formation within the watershed.New hydrological insights for the regionPrincipal component analysis (PCA) shows Niobrara-influenced inflows have distinctive geochemistry, particularly with respect to Na, Mg, SO42−, and Se. Uranium concentrations are also greater in Niobrara-influenced inflows. During the irrigation season, median dissolved solids, Se, and U concentrations in Niobrara-influenced inflows were 83%, 646%, and 55%, respectively, greater than medians where Niobrara Formation surface exposures were absent. During the non-irrigation season, which better reflects geologic influence, the differences were more striking. Median dissolved solids, Se, and U concentrations in Niobrara-influenced inflows were 288%, 863%, and 155%, respectively, greater than median concentrations where the Niobrara Formation was absent. Identification of the Niobrara Formation as a disproportionate source for dissolved solids, Se, and U will allow for more targeted studies and management, particularly where exposures underlie irrigated agriculture.

Photocatalytic oxidation of polycyclic aromatic hydrocarbons: Intermediates identification and toxicity testing

International Nuclear Information System (INIS)

Woo, O.T.; Chung, W.K.; Wong, K.H.; Chow, Alex T.; Wong, P.K.

2009-01-01

Polycyclic aromatic hydrocarbons (PAHs) are hydrophobic pollutants and their low water solubility limits their degradation in aqueous solution. The presence of water-miscible solvent such as acetone can increase the water solubility of PAHs, however acetone will also affect the degradation of PAH. In this study the effects of acetone on the photocatalytic degradation efficiency and pathways of 5 selected PAHs, namely naphthalene (2 rings), acenaphthylene (3 rings), phenanthrene (3 rings), anthracene (3 rings) and benzo[a]anthracene (4 rings) were investigated. The Microtox toxicity test was used to determine whether the PCO system can completely detoxify the parental PAHs and its intermediates. The addition of 16% acetone can greatly alter the degradation pathway of naphthalene and anthracene. Based on intermediates identified from degradation of the 5 PAHs, the location of parental PAHs attacked by reactive free radicals can be correlated with the localization energies of different positions of the compound. For toxicity analysis, irradiation by UV light was found to induce acute toxicity by generating intermediates/degradation products from PAHs and possibly acetone. Lastly, all PAHs (10 mg l -1 ) can be completely detoxified by titanium dioxide (100 mg l -1 ) within 24 h under UVA irradiation (3.9 mW cm -2 ).

E2 - an intermediate-age LMC cluster

International Nuclear Information System (INIS)

Schommer, R.A.; Olszewski, E.W.; Aaronson, M.; Steward Observatory, Tucson, AZ)

1986-01-01

A color-magnitude diagram is presented for the faint star cluster E2, located near the tip of the Magellanic Stream. The main-sequence turnoff, a few giants, and a giant clump can be discerned. Comparisons with VandenBerg models show E2 to be a 1.5 Gyr old cluster with abundance Z of about 0.01 at the distance of the LMC, and thus similar to the more populous intermediate-age LMC clusters. The existence of cluster formation at a large distance from the LMC center (E2 is at almost 8 deg radius) is discussed in the context of the star-formation history, structure, and kinematics of the outer halo of the Large Magellanic Cloud. 42 references

Freshening of Antarctic Intermediate Water in the South Atlantic Ocean in 2005-2014

Science.gov (United States)

Yao, Wenjun; Shi, Jiuxin; Zhao, Xiaolong

2017-07-01

Basin-scale freshening of Antarctic Intermediate Water (AAIW) is reported to have occurred in the South Atlantic Ocean during the period from 2005 to 2014, as shown by the gridded monthly means of the Array for Real-time Geostrophic Oceanography (Argo) data. This phenomenon was also revealed by two repeated transects along a section at 30° S, performed during the World Ocean Circulation Experiment Hydrographic Program. Freshening of the AAIW was compensated for by a salinity increase of thermocline water, indicating a hydrological cycle intensification. This was supported by the precipitation-minus-evaporation change in the Southern Hemisphere from 2000 to 2014. Freshwater input from atmosphere to ocean surface increased in the subpolar high-precipitation region and vice versa in the subtropical high-evaporation region. Against the background of hydrological cycle changes, a decrease in the transport of Agulhas Leakage (AL), which was revealed by the simulated velocity field, was proposed to be a contributor to the associated freshening of AAIW. Further calculation showed that such a decrease could account for approximately 53 % of the observed freshening (mean salinity reduction of about 0.012 over the AAIW layer). The estimated variability of AL was inferred from a weakening of wind stress over the South Indian Ocean since the beginning of the 2000s, which would facilitate freshwater input from the source region. The mechanical analysis of wind data here was qualitative, but it is contended that this study would be helpful to validate and test predictably coupled sea-air model simulations.

In vitro formation of metabolic-intermediate cytochrome P450 complexes in rabbit liver microsomes by tiamulin and various macrolides.

Science.gov (United States)

Carletti, Monica; Gusson, Federica; Zaghini, Anna; Dacasto, Mauro; Marvasi, Luigi; Nebbia, Carlo

2003-01-01

Tiamulin and a number of macrolides were evaluated as to their ability in forming metabolic-intermediate (MI) complexes with cytochrome P450 in liver microsomes from rabbits bred for meat production. Complex formation, which occurred only in preparations where the expression of P450 3A was increased as the result of rifampicin pre-treatment and with different kinetics, was in the order tiamulin > erythromycin > TAO approximately roxithromycin approximately tylosin and did not take place with tilmicosin and spiramycin. Most of the tested compounds underwent an oxidative N-dealkylation and a good relationship could be found between the rate of N-dealkylase activity in induced preparations and the aptitude in generating MI complexes. Although the results from in vitro studies should be interpreted with caution, it is suggested that the potential for in vivo drug interactions also exists in the rabbit for tiamulin and for four out of the six tested macrolides.

Formation of Reactive Intermediates, Color, and Antioxidant Activity in the Maillard Reaction of Maltose in Comparison to d-Glucose.

Science.gov (United States)

Kanzler, Clemens; Schestkowa, Helena; Haase, Paul T; Kroh, Lothar W

2017-10-11

In this study, the Maillard reaction of maltose and d-glucose in the presence of l-alanine was investigated in aqueous solution at 130 °C and pH 5. The reactivity of both carbohydrates was compared in regards of their degradation, browning, and antioxidant activity. In order to identify relevant differences in the reaction pathways, the concentrations of selected intermediates such as 1,2-dicarbonyl compounds, furans, furanones, and pyranones were determined. It was found, that the degradation of maltose predominantly yields 1,2-dicarbonyls that still carry a glucosyl moiety and thus subsequent reactions to HMF, furfural, and 2-acetylfuran are favored due to the elimination of d-glucose, which is an excellent leaving group in aqueous solution. Consequently, higher amounts of these heterocycles are formed from maltose. 3-deoxyglucosone and 3-deoxygalactosone represent the only relevant C 6 -1,2-dicarbonyls in maltose incubations and are produced in nearly equimolar amounts during the first 60 min of heating as byproducts of the HMF formation.

Studies of deep water formation and circulation in the Weddell Sea using natural and anthropogenic tracers

International Nuclear Information System (INIS)

Schlosser, Peter; Bayer, Reinhold

1991-01-01

The application of natural and anthropogenic trace substances in oceanographic studies of the Weddell Sea is reviewed. The potential of some steady-state and transient tracers (tritium, CFC-11 and CFC-12, 18 O, and helium isotopes) for studies of deep water formation and circulation is discussed on the basis of data sets collected mainly on cruises of R/V 'Polastern' to the Weddell Sea during the 1980s. CFC/ tritium ratio dating of young water masses is applied to estimate mean age and transit times of water involved in Weddell Sea Bottom Water formation. The history of the CFC-11/tritium ratio through time is derived for Weddell Sea shelf waters. (author). 36 refs.; 18 figs

Green rust formation controls nutrient availability in a ferruginous water column

DEFF Research Database (Denmark)

Zegeye, Asfaw; Bonneville, Steeve; Benning, Liane G.

2013-01-01

a mechanism for reconstructing ancient ocean chemistry. Such reconstructions depend, however, on precise knowledge of the iron minerals formed in the water column. Here, we combine mineralogical and geochemical analyses to demonstrate formation of the mixed-valence iron mineral, green rust, in ferruginous...

Competence formation and post-graduate education in the public water sector in Indonesia

Directory of Open Access Journals (Sweden)

J. M. Kaspersma

2012-07-01

Full Text Available The water sector is dependent on effective institutions and organisations, and, therefore, on strong competences at the individual level. In this paper we describe competence formation and competence needs in a case study of the Directorate General of Water Resources (DGWR in the Ministry of Public Works in Indonesia. A framework is introduced for the water sector comprising three aggregate competences for technical issues, management, and governance, and a meta-competence for continuous learning and innovation. The four competences are further organised in a T-shaped competence profile. Though DGWR professionals have a firmly "technical" orientation, both surveys and interviews reveal a strong perceived requirement for other competences: in particular the learning meta-competence, as well as the aggregate competence for management. The aggregate competence for governance systematically scores lower. Further, a discrepancy appears to exist between the competences that staff perceive as needed in daily work, and those that can be acquired during post-graduate water education.

In both locally-based and international post-graduate water education, the aggregate competences for management as well as governance are reportedly addressed modestly, if at all. With low competence in these fields, it is difficult for professionals to communicate and collaborate effectively in a multidisciplinary way. As a result, the horizontal bar of the T-shaped profile remains weakly developed. In international post-graduate education, this is partially compensated by the attention to continuous learning and innovation. The exposure to a different culture and learning format is experienced as fundamentally formative.

Competence formation and post-graduate education in the public water sector in Indonesia

Science.gov (United States)

Kaspersma, J. M.; Alaerts, G. J.; Slinger, J. H.

2012-07-01

The water sector is dependent on effective institutions and organisations, and, therefore, on strong competences at the individual level. In this paper we describe competence formation and competence needs in a case study of the Directorate General of Water Resources (DGWR) in the Ministry of Public Works in Indonesia. A framework is introduced for the water sector comprising three aggregate competences for technical issues, management, and governance, and a meta-competence for continuous learning and innovation. The four competences are further organised in a T-shaped competence profile. Though DGWR professionals have a firmly "technical" orientation, both surveys and interviews reveal a strong perceived requirement for other competences: in particular the learning meta-competence, as well as the aggregate competence for management. The aggregate competence for governance systematically scores lower. Further, a discrepancy appears to exist between the competences that staff perceive as needed in daily work, and those that can be acquired during post-graduate water education. In both locally-based and international post-graduate water education, the aggregate competences for management as well as governance are reportedly addressed modestly, if at all. With low competence in these fields, it is difficult for professionals to communicate and collaborate effectively in a multidisciplinary way. As a result, the horizontal bar of the T-shaped profile remains weakly developed. In international post-graduate education, this is partially compensated by the attention to continuous learning and innovation. The exposure to a different culture and learning format is experienced as fundamentally formative.

Intermediate treatments

Science.gov (United States)

John R. Jones; Wayne D. Shepperd

1985-01-01

Intermediate treatments are those applied after a new stand is successfully established and before the final harvest. These include not only intermediate cuttings - primarily thinning - but also fertilization, irrigation, and protection of the stand from damaging agents.

Photochemical transformation of phenylurea herbicides in surface waters: a model assessment of persistence, and implications for the possible generation of hazardous intermediates.

Science.gov (United States)

Fabbri, Debora; Minella, Marco; Maurino, Valter; Minero, Claudio; Vione, Davide

2015-01-01

This work models the phototransformation kinetics in surface waters of five phenylurea herbicides (diuron, fenuron, isoproturon, metoxuron and chlortoluron), for which important photochemical parameters are available in the literature (direct photolysis quantum yields and reaction rate constants with ·OH, CO3(-·) and the triplet states of chromophoric dissolved organic matter, (3)CDOM*). Model calculations suggest that isoproturon and metoxuron would be the least photochemically persistent and diuron the most persistent compound. Reactions with ·OH and (3)CDOM* would be the main phototransformation pathways for all compounds in the majority of environmental conditions. Reaction with CO3(-) could be important in waters with low dissolved organic carbon (DOC), while direct photolysis would be negligible for fenuron, quite important for chlortoluron, and somewhat significant for the other compounds. The direct photolysis of metoxuron and diuron is known to increase toxicity, and such a photoreaction pathway would be enhanced at intermediate DOC values (1-4 mg C L(1)). The reaction between phenylureas and ·OH is known to produce toxic intermediates, differently from (3)CDOM*. Therefore, the shift of reactivity from ·OH to (3)CDOM* with increasing DOC could reduce the environmental impact of photochemical transformation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Supercritical water oxidation of ion exchange resins: Degradation mechanisms

Energy Technology Data Exchange (ETDEWEB)

Leybros, A.; Roubaud, A. [CEA Marcoule, DEN DTCD SPDE LFSM, F-30207 Bagnols Sur Ceze (France); Guichardon, P. [Ecole Cent Marseille, F-13451 Marseille 20 (France); Boutin, O. [Aix Marseille Univ, UMR CNRS 6181, F-13545 Aix En Provence 4 (France)

2010-07-01

Spent ion exchange resins are radioactive process wastes for which there is no satisfactory industrial treatment. Supercritical water oxidation could offer a viable treatment alternative to destroy the organic structure of resins and contain radioactivity. IER degradation experiments were carried out in a continuous supercritical water reactor. Total organic carbon degradation rates in the range of 95-98% were obtained depending on operating conditions. GC-MS chromatography analyses were carried out to determine intermediate products formed during the reaction. Around 50 species were identified for cationic and anionic resins. Degradation of poly-styrenic structure leads to the formation of low molecular weight compounds. Benzoic acid, phenol and acetic acid are the main compounds. However, other products are detected in appreciable yields such as phenolic species or heterocycles, for anionic IERs degradation. Intermediates produced by intramolecular rearrangements are also obtained. A radical degradation mechanism is proposed for each resin. In this overall mechanism, several hypotheses are foreseen, according to HOO center dot radical attack sites. (authors)

Origin and evolution of formation water at the Jujo-Tecominoacan oil reservoir, Gulf of Mexico. Part 1: Chemical evolution and water-rock interaction

Energy Technology Data Exchange (ETDEWEB)

Birkle, Peter, E-mail: birkle@iie.org.mx [Instituto de Investigaciones Electricas (IIE), Gerencia de Geotermia, Av. Reforma 113, Cuernavaca, Morelos 62490 (Mexico); Garcia, Bernardo Martinez; Milland Padron, Carlos M. [PEMEX Exploracion y Produccion, Region Sur, Activo Integral Bellota-Jujo, Diseno de Explotacion, Cardenas, Tabasco (Mexico)

2009-04-15

The origin and evolution of formation water from Upper Jurassic to Upper Cretaceous mudstone-packstone-dolomite host rocks at the Jujo-Tecominoacan oil reservoir, located onshore in SE-Mexico at a depth from 5200 to 6200 m.b.s.l., have been investigated, using detailed water geochemistry from 12 producer wells and six closed wells, and related host rock mineralogy. Saline waters of Cl-Na type with total dissolved solids from 10 to 23 g/L are chemically distinct from hypersaline Cl-Ca-Na and Cl-Na-Ca type waters with TDS between 181 and 385 g/L. Bromine/Cl and Br/Na ratios suggest the subaerial evaporation of seawater beyond halite precipitation to explain the extreme hypersaline components, while less saline samples were formed by mixing of high salinity end members with surface-derived, low salinity water components. The dissolution of evaporites from adjacent salt domes has little impact on present formation water composition. Geochemical simulations with Harvie-M{phi}ller-Weare and PHRQPITZ thermodynamic data sets suggest secondary fluid enrichment in Ca, HCO{sub 3} and Sr by water-rock interaction. The volumetric mass balance between Ca enrichment and Mg depletion confirms dolomitization as the major alteration process. Potassium/Cl ratios below evaporation trajectory are attributed to minor precipitation of K feldspar and illitization without evidence for albitization at the Jujo-Tecominoacan reservoir. The abundance of secondary dolomite, illite and pyrite in drilling cores from reservoir host rock reconfirms the observed water-rock exchange processes. Sulfate concentrations are controlled by anhydrite solubility as indicated by positive SI-values, although anhydrite deposition is limited throughout the lithological reservoir column. The chemical variety of produced water at the Jujo-Tecominoacan oil field is related to a sequence of primary and secondary processes, including infiltration of evaporated seawater and original meteoric fluids, the subsequent

Origin and evolution of formation water at the Jujo-Tecominoacan oil reservoir, Gulf of Mexico. Part 1: Chemical evolution and water-rock interaction

International Nuclear Information System (INIS)

Birkle, Peter; Garcia, Bernardo Martinez; Milland Padron, Carlos M.

2009-01-01

The origin and evolution of formation water from Upper Jurassic to Upper Cretaceous mudstone-packstone-dolomite host rocks at the Jujo-Tecominoacan oil reservoir, located onshore in SE-Mexico at a depth from 5200 to 6200 m.b.s.l., have been investigated, using detailed water geochemistry from 12 producer wells and six closed wells, and related host rock mineralogy. Saline waters of Cl-Na type with total dissolved solids from 10 to 23 g/L are chemically distinct from hypersaline Cl-Ca-Na and Cl-Na-Ca type waters with TDS between 181 and 385 g/L. Bromine/Cl and Br/Na ratios suggest the subaerial evaporation of seawater beyond halite precipitation to explain the extreme hypersaline components, while less saline samples were formed by mixing of high salinity end members with surface-derived, low salinity water components. The dissolution of evaporites from adjacent salt domes has little impact on present formation water composition. Geochemical simulations with Harvie-Mφller-Weare and PHRQPITZ thermodynamic data sets suggest secondary fluid enrichment in Ca, HCO 3 and Sr by water-rock interaction. The volumetric mass balance between Ca enrichment and Mg depletion confirms dolomitization as the major alteration process. Potassium/Cl ratios below evaporation trajectory are attributed to minor precipitation of K feldspar and illitization without evidence for albitization at the Jujo-Tecominoacan reservoir. The abundance of secondary dolomite, illite and pyrite in drilling cores from reservoir host rock reconfirms the observed water-rock exchange processes. Sulfate concentrations are controlled by anhydrite solubility as indicated by positive SI-values, although anhydrite deposition is limited throughout the lithological reservoir column. The chemical variety of produced water at the Jujo-Tecominoacan oil field is related to a sequence of primary and secondary processes, including infiltration of evaporated seawater and original meteoric fluids, the subsequent mixing of

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.

Multiple ways of producing intermediate and silicic rocks within Thingmúli and other Icelandic volcanoes

DEFF Research Database (Denmark)

Charreteur, Gilles; Tegner, Christian; Haase, Karsten

2013-01-01

Major and trace element compositions of rocks and coexisting phenocrysts of the ThingmA(0)li volcano suggest a revision of the existing models for the formation of intermediate and silicic melts in Iceland. The new data define two compositional tholeiitic trends with a significant gap between the...... between the compositions of intermediate and silicic rocks and plate tectonic setting, therefore, should be avoided....

Enhancement of tribofilm formation from water lubricated PEEK composites by copper nanowires

Science.gov (United States)

Gao, Chuanping; Fan, Shuguang; Zhang, Shengmao; Zhang, Pingyu; Wang, Qihua

2018-06-01

A high-performance tribofilm is crucial to enhance the tribological performance of tribomaterials. In order to promote tribofilm formation under water lubrication conditions, copper nanowires as a functional nanomaterial were filled into neat polyetheretherketone (PEEK) and PEEK10SCF8Gr (i.e., PEEK filled with 10 vol.% short carbon fibers and 8 vol.% graphite flakes). The results show that the addition of copper nanowires and a greater applied load can enhance materials transfer and tribofilm formation during sliding process. Moreover, copper nanowires can share a part of applied load, and retard the fatigue effect to some extent. In addition, copper nanowires, carbon fibers and graphite can synergistically improve the tribological performance and the tribofilm formation under water lubrication and severe working conditions. In particular, only 0.5 vol.% copper nanowires can form a high-performance tribofilm, which endows superior lubricating property and wear resistance capacity of the PEEK10SCF8Gr. Furthermore, the surface analysis indicates that the tribofilm contains some transferred materials and the products from tribochemical reactions as well.

Assessment of scale formation and corrosion of drinking water supplies in Ilam city (Iran)

OpenAIRE

Zabihollah Yousefi; Farzad Kazemi; Reza Ali Mohammadpour

2016-01-01

Background: Scaling and corrosion are the two most important indexes in water quality evaluation. Pollutants are released in water due to corrosion of pipelines. The aim of this study is to assess the scale formation and corrosion of drinking water supplies in Ilam city (Iran). Methods: This research is a descriptive and cross-sectional study which is based on the 20 drinking water sources in Ilam city. Experiments were carried out in accordance with the Water and Wastewater Co. ...

Modeling the formation of soluble microbial products (SMP in drinking water biofiltration

Directory of Open Access Journals (Sweden)

Yu Xin

2008-09-01

Full Text Available Both a theoretical and an empirical model were developed for predicting the formation of soluble microbial products (SMP during drinking water biofiltration. Four pilot-scale biofilters with ceramsite as the medium were fed with different acetate loadings for the determination of SMP formation. Using numerically simulated and measured parameters, the theoretical model was developed according to the substrate and biomass balance. The results of this model matched the measured data better for higher SMP formation but did not fit well when SMP formation was lower. In order to better simulate the reality and overcome the difficulties of measuring the kinetic parameters, a simpler empirical model was also developed. In this model, SMP formation was expressed as a function of fed organic loadings and the depth of the medium, and a much better fit was obtained.

NDMA formation from amine-based pharmaceuticals--impact from prechlorination and water matrix.

Science.gov (United States)

Shen, Ruqiao; Andrews, Susan A

2013-05-01

The presence of N-nitrosodimethylamine (NDMA) in drinking water is most commonly associated with the chloramination of amine-based precursors. One option to control the NDMA formation is to remove the precursors via pre-oxidation, and prechlorination is among the most effective options in reducing NDMA formation. However, most of the findings to-date are based on single-precursor scenarios using the model precursor dimethylamine (DMA) and natural organic matter (NOM), while few studies have considered the potential interactions between water matrix components and the target precursors when investigating the prechlorination impact. Specifically, little is known for the behaviour of amine-based pharmaceuticals which have recently been reported to contribute to NDMA formation upon chloramination. This work demonstrates that prechlorination can affect both the ultimate NDMA conversion and the reaction kinetics from selected pharmaceuticals, and the nature and extent of the impact was compound-specific and matrix-specific. In the absence of NOM, the NDMA formation from most pharmaceuticals was reduced upon prechlorination, except for sumatriptan which showed a consistent increase in NDMA formation with increasing free chlorine contact time. In the presence of NOM, prechlorination was shown to enhance initial reactions by reducing the binding between NOM and pharmaceuticals, but prolonged prechlorination broke down NOM into smaller products which could then form new bonds with pharmaceuticals and thus inhibit their further conversion into NDMA. Copyright © 2013 Elsevier Ltd. All rights reserved.

Perspective: Spectroscopy and kinetics of small gaseous Criegee intermediates

International Nuclear Information System (INIS)

Lee, Yuan-Pern

2015-01-01

The Criegee intermediates, carbonyl oxides proposed by Criegee in 1949 as key intermediates in the ozonolysis of alkenes, play important roles in many aspects of atmospheric chemistry. Because direct detection of these gaseous intermediates was unavailable until recently, previous understanding of their reactions, derived from indirect experimental evidence, had great uncertainties. Recent laboratory detection of the simplest Criegee intermediate CH 2 OO and some larger members, produced from ultraviolet irradiation of corresponding diiodoalkanes in O 2 , with various methods such as photoionization, ultraviolet absorption, infrared absorption, and microwave spectroscopy opens a new door to improved understanding of the roles of these Criegee intermediates. Their structures and spectral parameters have been characterized; their significant zwitterionic nature is hence confirmed. CH 2 OO, along with other products, has also been detected directly with microwave spectroscopy in gaseous ozonolysis reactions of ethene. The detailed kinetics of the source reaction, CH 2 I + O 2 , which is critical to laboratory studies of CH 2 OO, are now understood satisfactorily. The kinetic investigations using direct detection identified some important atmospheric reactions, including reactions with NO 2 , SO 2 , water dimer, carboxylic acids, and carbonyl compounds. Efforts toward the characterization of larger Criegee intermediates and the investigation of related reactions are in progress. Some reactions of CH 3 CHOO are found to depend on conformation. This perspective examines progress toward the direct spectral characterization of Criegee intermediates and investigations of the associated reaction kinetics, and indicates some unresolved problems and prospective challenges for this exciting field of research

Disinfection byproduct formation in reverse-osmosis concentrated and lyophilized natural organic matter from a drinking water source.

Science.gov (United States)

Pressman, Jonathan G; McCurry, Daniel L; Parvez, Shahid; Rice, Glenn E; Teuschler, Linda K; Miltner, Richard J; Speth, Thomas F

2012-10-15

Drinking water treatment and disinfection byproduct (DBP) research can be complicated by natural organic matter (NOM) temporal variability. NOM preservation by lyophilization (freeze-drying) has been long practiced to address this issue; however, its applicability for drinking water research has been limited because the selected NOM sources are atypical of most drinking water sources. The purpose of this research was to demonstrate that reconstituted NOM from a lyophilized reverse-osmosis (RO) concentrate of a typical drinking water source closely represents DBP formation in the original NOM. A preliminary experiment assessed DBP formation kinetics and yields in concentrated NOM, which demonstrated that chlorine decays faster in concentrate, in some cases leading to altered DBP speciation. Potential changes in NOM reactivity caused by lyophilization were evaluated by chlorination of lyophilized and reconstituted NOM, its parent RO concentrate, and the source water. Bromide lost during RO concentration was replaced by adding potassium bromide prior to chlorination. Although total measured DBP formation tended to decrease slightly and unidentified halogenated organic formation tended to increase slightly as a result of RO concentration, the changes associated with lyophilization were minor. In lyophilized NOM reconstituted back to source water TOC levels and then chlorinated, the concentrations of 19 of 21 measured DBPs, constituting 96% of the total identified DBP mass, were statistically indistinguishable from those in the chlorinated source water. Furthermore, the concentrations of 16 of 21 DBPs in lyophilized NOM reconstituted back to the RO concentrate TOC levels, constituting 86% DBP mass, were statistically indistinguishable from those in the RO concentrate. This study suggests that lyophilization can be used to preserve concentrated NOM without substantially altering the precursors to DBP formation. Published by Elsevier Ltd.

The Metallicity Evolution of Blue Compact Dwarf Galaxies from the Intermediate Redshift to the Local Universe

Science.gov (United States)

Lian, Jianhui; Hu, Ning; Fang, Guanwen; Ye, Chengyun; Kong, Xu

2016-03-01

We present oxygen abundance measurements for 74 blue compact dwarf (BCD) galaxies in the redshift range of [0.2, 0.5] using the strong-line method. The spectra of these objects are taken using Hectospec on the Multiple Mirror Telescope. More than half of these BCDs had dust attenuation corrected using the Balmer decrement method. For comparison, we also selected a sample of 2023 local BCDs from the Sloan Digital Sky Survey (SDSS) database. Based on the local and intermediate-z BCD samples, we investigated the cosmic evolution of the metallicity, star formation rate (SFR), and Dn(4000) index. Compared with local BCDs, the intermediate-z BCDs had a systematically higher R23 ratio but a similar O32 ratio. Interestingly, no significant deviation in the mass-metallicity (MZ) relation was found between the intermediate-z and local BCDs. Besides the metallicity, the intermediate-z BCDs also exhibited an SFR distribution that was consistent with local BCDs, suggesting a weak dependence on redshift. The intermediate-z BCDs seemed to be younger than the local BCDs with lower Dn(4000) index values. The insignificant deviation in the mass-metallicity and mass-SFR relations between intermediate-z and local BCDs indicates that the relations between the global parameters of low-mass compact galaxies may be universal. These results from low-mass compact galaxies could be used to place important observational constraints on galaxy formation and evolution models.

THE METALLICITY EVOLUTION OF BLUE COMPACT DWARF GALAXIES FROM THE INTERMEDIATE REDSHIFT TO THE LOCAL UNIVERSE

International Nuclear Information System (INIS)

Lian, Jianhui; Hu, Ning; Ye, Chengyun; Kong, Xu; Fang, Guanwen

2016-01-01

We present oxygen abundance measurements for 74 blue compact dwarf (BCD) galaxies in the redshift range of [0.2, 0.5] using the strong-line method. The spectra of these objects are taken using Hectospec on the Multiple Mirror Telescope. More than half of these BCDs had dust attenuation corrected using the Balmer decrement method. For comparison, we also selected a sample of 2023 local BCDs from the Sloan Digital Sky Survey (SDSS) database. Based on the local and intermediate-z BCD samples, we investigated the cosmic evolution of the metallicity, star formation rate (SFR), and D n (4000) index. Compared with local BCDs, the intermediate-z BCDs had a systematically higher R23 ratio but a similar O32 ratio. Interestingly, no significant deviation in the mass–metallicity (MZ) relation was found between the intermediate-z and local BCDs. Besides the metallicity, the intermediate-z BCDs also exhibited an SFR distribution that was consistent with local BCDs, suggesting a weak dependence on redshift. The intermediate-z BCDs seemed to be younger than the local BCDs with lower D n (4000) index values. The insignificant deviation in the mass–metallicity and mass–SFR relations between intermediate-z and local BCDs indicates that the relations between the global parameters of low-mass compact galaxies may be universal. These results from low-mass compact galaxies could be used to place important observational constraints on galaxy formation and evolution models

THE METALLICITY EVOLUTION OF BLUE COMPACT DWARF GALAXIES FROM THE INTERMEDIATE REDSHIFT TO THE LOCAL UNIVERSE

Energy Technology Data Exchange (ETDEWEB)

Lian, Jianhui; Hu, Ning; Ye, Chengyun; Kong, Xu [CAS Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, Hefei, Anhui 230026 (China); Fang, Guanwen, E-mail: ljhhw@mail.ustc.edu.cn, E-mail: xkong@ustc.edu.cn [Institute for Astronomy and History of Science and Technology, Dali University, Dali 671003 (China)

2016-03-01

We present oxygen abundance measurements for 74 blue compact dwarf (BCD) galaxies in the redshift range of [0.2, 0.5] using the strong-line method. The spectra of these objects are taken using Hectospec on the Multiple Mirror Telescope. More than half of these BCDs had dust attenuation corrected using the Balmer decrement method. For comparison, we also selected a sample of 2023 local BCDs from the Sloan Digital Sky Survey (SDSS) database. Based on the local and intermediate-z BCD samples, we investigated the cosmic evolution of the metallicity, star formation rate (SFR), and D{sub n}(4000) index. Compared with local BCDs, the intermediate-z BCDs had a systematically higher R23 ratio but a similar O32 ratio. Interestingly, no significant deviation in the mass–metallicity (MZ) relation was found between the intermediate-z and local BCDs. Besides the metallicity, the intermediate-z BCDs also exhibited an SFR distribution that was consistent with local BCDs, suggesting a weak dependence on redshift. The intermediate-z BCDs seemed to be younger than the local BCDs with lower D{sub n}(4000) index values. The insignificant deviation in the mass–metallicity and mass–SFR relations between intermediate-z and local BCDs indicates that the relations between the global parameters of low-mass compact galaxies may be universal. These results from low-mass compact galaxies could be used to place important observational constraints on galaxy formation and evolution models.

Mode Water Formation via Cabbeling and Submesoscale Lateral Mixing at a Strained Thermohaline Front

Science.gov (United States)

Thomas, L. N.; Shakespeare, C. J.

2014-12-01

Mode waters play an important role in interannual climate variability through the temporary storage of heat and carbon in the ocean. The mechanisms explaining their formation are not well understood but appear to be shaped by the dynamics of the ocean fronts that mark their poleward extent. We explore a mode water formation mechanism that has a clear connection to fronts and involves cabbeling. Cabbeling refers to the process by which two water masses of equal density but different temperature and salinity are combined to create a new, denser water mass, as a result of nonlinearities in the equation of state for seawater. The work is motivated in part by recent observations of an extremely sharp, density-compensated front at the north wall of the Gulf Stream, the boundary between the subtropical and subpolar gyres. Here, the inter-gyre salinity/temperature difference is compressed into a span of a few kilometers, making the flow susceptible to cabbeling. The sharpness of the front is caused by frontogenetic strain, which is presumably balanced by submesoscale lateral mixing processes. We study this balance with a simple analytical model of a thermohaline front forced by uniform strain and derive a scaling for the amount of water mass transformation resulting from the ensuing cabbeling. The theory suggests that this mechanism could be responsible for persistent, hence significant, mode water formation. As such, it represents a submesoscale process that impacts the ocean on basin scales that should be resolved or parameterized in realistic numerical simulations.

Environmental conditions for the formation of insoluble Tc in water ponds located above paddy fields

International Nuclear Information System (INIS)

Ishii, Nobuyoshi; Koiso, Hiroyuki; Takeda, Hiroshi; Uchida, Shigeo

2008-01-01

Optimum conditions for the formation of insoluble Tc (Tc in >0.2 μm size fraction) were studied using a microcosm including water ponds above a paddy field to understand Tc behavior in such fields. In the microcosm, soluble TcO 4 - was converted to insoluble forms, but no changes in the form of Tc were observed in filtered microcosm samples which were microorganisms-free. The formation of insoluble Tc was inhibited by the addition of the antibiotic chloramphenicol. In addition, the reduction of soluble Tc(VII)O 4 - to low-valence oxide was not observed in the filtered microcosm samples, although reducing conditions were present. These results indicated that bacteria were involved in the formation of insoluble Tc. Since oxidizing conditions influence bacterial metabolism, the formation of insoluble Tc by bacteria was studied under aerobic and anaerobic conditions. The results showed that anaerobic conditions were favorable for the formation of insoluble Tc. In addition, the addition of formate as an electron donor to a microcosm sample facilitated the formation of insoluble Tc. The results suggested that insoluble Tc in the water ponds above paddy fields was caused by bacteria, which were shown to couple the oxidation of formate to the reduction of Tc(VII) during anaerobic respiration

Intermediates and the folding of proteins L and G

Energy Technology Data Exchange (ETDEWEB)

Brown, Scott; Head-Gordon, Teresa

2003-07-01

We use a minimalist protein model, in combination with a sequence design strategy, to determine differences in primary structure for proteins L and G that are responsible for the two proteins folding through distinctly different folding mechanisms. We find that the folding of proteins L and G are consistent with a nucleation-condensation mechanism, each of which is described as helix-assisted {beta}-1 and {beta}-2 hairpin formation, respectively. We determine that the model for protein G exhibits an early intermediate that precedes the rate-limiting barrier of folding and which draws together misaligned secondary structure elements that are stabilized by hydrophobic core contacts involving the third {beta}-strand, and presages the later transition state in which the correct strand alignment of these same secondary structure elements is restored. Finally the validity of the targeted intermediate ensemble for protein G was analyzed by fitting the kinetic data to a two-step first order reversible reaction, proving that protein G folding involves an on-pathway early intermediate, and should be populated and therefore observable by experiment.

Formation of assimilable organic carbon during oxidation of natural waters with ozone, chlorine dioxide, chlorine, permanganate, and ferrate.

Science.gov (United States)

Ramseier, Maaike K; Peter, Andreas; Traber, Jacqueline; von Gunten, Urs

2011-02-01

Five oxidants, ozone, chlorine dioxide, chlorine, permanganate, and ferrate were studied with regard to the formation of assimilable organic carbon (AOC) and oxalate in absence and presence of cyanobacteria in lake water matrices. Ozone and ferrate formed significant amounts of AOC, i.e. more than 100 μg/L AOC were formed with 4.6 mg/L ozone and ferrate in water with 3.8 mg/L dissolved organic carbon. In the same water samples chlorine dioxide, chlorine, and permanganate produced no or only limited AOC. When cyanobacterial cells (Aphanizomenon gracile) were added to the water, an AOC increase was detected with ozone, permanganate, and ferrate, probably due to cell lysis. This was confirmed by the increase of extracellular geosmin, a substance found in the selected cyanobacterial cells. AOC formation by chlorine and chlorine dioxide was not affected by the presence of the cells. The formation of oxalate upon oxidation was found to be a linear function of the oxidant consumption for all five oxidants. The following molar yields were measured in three different water matrices based on oxidant consumed: 2.4-4.4% for ozone, 1.0-2.8% for chlorine dioxide and chlorine, 1.1-1.2% for ferrate, and 11-16% for permanganate. Furthermore, oxalate was formed in similar concentrations as trihalomethanes during chlorination (yield ∼ 1% based on chlorine consumed). Oxalate formation kinetics and stoichiometry did not correspond to the AOC formation. Therefore, oxalate cannot be used as a surrogate for AOC formation during oxidative water treatment. Copyright © 2010 Elsevier Ltd. All rights reserved.

Formation mechanism and luminescence appearance of Mn-doped zinc silicate particles synthesized in supercritical water

International Nuclear Information System (INIS)

Takesue, Masafumi; Suino, Atsuko; Hakuta, Yukiya; Hayashi, Hiromichi; Smith, Richard Lee

2008-01-01

Luminescence appearance of Mn-doped zinc silicate (Zn 2 SiO 4 :Mn 2+ , ZSM) formed in supercritical water at 400 deg. C and 29 MPa at reaction times from 1 to 4320 min was studied in the relation to its phase formation mechanism. Appearance of luminescent ZSM from green emission by α-ZSM and yellow emission by β-ZSM occurred over the same time period during the onset of phase formation at a reaction time of 2 min. Luminescence appeared at a much lower temperature and at shorter reaction times than the conventional solid-state reaction. Needle-like-shaped α-ZSM was the most stable particle shape and phase in the supercritical water reaction environment and particles formed via two routes: a homogenous nucleation route and a heterogenous route that involves solid-state diffusion and recrystallization. - Graphical abstract: Luminescence appearance of Mn-doped zinc silicate (Zn 2 SiO 4 :Mn 2+ , ZSM) formed in supercritical water at 400 deg. C and 29 MPa were studied in the relation to its phase formation mechanism. Green emission by α-ZSM and yellow emission by β-ZSM occurred over the same time period during the onset of phase formation

An evaluation of water quality in private drinking water wells near natural gas extraction sites in the Barnett Shale formation.

Science.gov (United States)

Fontenot, Brian E; Hunt, Laura R; Hildenbrand, Zacariah L; Carlton, Doug D; Oka, Hyppolite; Walton, Jayme L; Hopkins, Dan; Osorio, Alexandra; Bjorndal, Bryan; Hu, Qinhong H; Schug, Kevin A

2013-09-03

Natural gas has become a leading source of alternative energy with the advent of techniques to economically extract gas reserves from deep shale formations. Here, we present an assessment of private well water quality in aquifers overlying the Barnett Shale formation of North Texas. We evaluated samples from 100 private drinking water wells using analytical chemistry techniques. Analyses revealed that arsenic, selenium, strontium and total dissolved solids (TDS) exceeded the Environmental Protection Agency's Drinking Water Maximum Contaminant Limit (MCL) in some samples from private water wells located within 3 km of active natural gas wells. Lower levels of arsenic, selenium, strontium, and barium were detected at reference sites outside the Barnett Shale region as well as sites within the Barnett Shale region located more than 3 km from active natural gas wells. Methanol and ethanol were also detected in 29% of samples. Samples exceeding MCL levels were randomly distributed within areas of active natural gas extraction, and the spatial patterns in our data suggest that elevated constituent levels could be due to a variety of factors including mobilization of natural constituents, hydrogeochemical changes from lowering of the water table, or industrial accidents such as faulty gas well casings.

Rapid shift and millennial-scale variations in Holocene North Pacific Intermediate Water ventilation.

Science.gov (United States)

Lembke-Jene, Lester; Tiedemann, Ralf; Nürnberg, Dirk; Gong, Xun; Lohmann, Gerrit

2018-05-22

The Pacific hosts the largest oxygen minimum zones (OMZs) in the world ocean, which are thought to intensify and expand under future climate change, with significant consequences for marine ecosystems, biogeochemical cycles, and fisheries. At present, no deep ventilation occurs in the North Pacific due to a persistent halocline, but relatively better-oxygenated subsurface North Pacific Intermediate Water (NPIW) mitigates OMZ development in lower latitudes. Over the past decades, instrumental data show decreasing oxygenation in NPIW; however, long-term variations in middepth ventilation are potentially large, obscuring anthropogenic influences against millennial-scale natural background shifts. Here, we use paleoceanographic proxy evidence from the Okhotsk Sea, the foremost North Pacific ventilation region, to show that its modern oxygenated pattern is a relatively recent feature, with little to no ventilation before six thousand years ago, constituting an apparent Early-Middle Holocene (EMH) threshold or "tipping point." Complementary paleomodeling results likewise indicate a warmer, saltier EMH NPIW, different from its modern conditions. During the EMH, the Okhotsk Sea switched from a modern oxygenation source to a sink, through a combination of sea ice loss, higher water temperatures, and remineralization rates, inhibiting ventilation. We estimate a strongly decreased EMH NPIW oxygenation of ∼30 to 50%, and increased middepth Pacific nutrient concentrations and carbon storage. Our results ( i ) imply that under past or future warmer-than-present conditions, oceanic biogeochemical feedback mechanisms may change or even switch direction, and ( ii ) provide constraints on the high-latitude North Pacific's influence on mesopelagic ventilation dynamics, with consequences for large oceanic regions. Copyright © 2018 the Author(s). Published by PNAS.

Formation of hydroxyl radical (sm-bulletOH) in illuminated surface waters contaminated with acidic mine drainage

International Nuclear Information System (INIS)

Allen, J.M.; Lucas, S.; Allen, S.K.

1996-01-01

Formation rates and steady-state concentrations of hydroxyl radical ( sm-bullet OH) in illuminated surface water samples collected in west-central Indiana that receive acidic mine drainage runoff are reported. Formation rates for sm-bullet OH in samples were measured by the addition of 1 x 10 -3 M benzene prior to illuminate in order to effectively scavenge all of the sm-bullet OH formed, thereby yielding phenol. The sm-bullet OH formation rates were calculated from the measured phenol formation rates. Steady-state concentrations of sm-bullet OH were measured by the addition of 5 x 10 -7 M nitrobenzene to the samples prior to illumination. Estimated sunlight sm-bullet OH formation rates range from 16 microM h -1 to 265 microM h -1 . Estimated sunlight steady-state sm-bullet OH concentrations range from 6.7 x 10 -15 to 4.0 x 10 -12 M. Both the formation rates and steady-state concentrations for sm-bullet OH are thus two to three orders of magnitude higher than values reported in the literature for other sunlit surface water samples. Due to the very high rates of formation and steady-state concentrations for sm-bullet OH in these samples, the authors conclude that aqueous-phase reactions involving sm-bullet OH represent a significant pathway by which organic pollutants in illuminated surface waters receiving acidic mine drainage runoff may be consumed

Gateways and Water Mass Mixing in the Late Cretaceous North Atlantic

Science.gov (United States)

Asgharian Rostami, M.; Martin, E. E.; MacLeod, K. G.; Poulsen, C. J.; Vande Guchte, A.; Haynes, S.

2017-12-01

Regions of intermediate/deep water formation and water-mass mixing in the North Atlantic are poorly defined for the Late Cretaceous, a time of gateway evolution and cooler conditions following the Mid Cretaceous greenhouse. Improved proxy data combined with modeling efforts are required to effectively evaluate the relationship between CO2, paleogeography, and circulation during this cooler interval. We analyzed and compiled latest Cretaceous (79 - 66 Ma) ɛNd and δ13C records from seven bathyal (paleodepths 0.2 - 2 km) and eight abyssal (paleodepths > 2 km) sites in the North Atlantic. Data suggest local downwelling of Northern Component Water (NCW; ɛNd -9.5 and δ13C 1.7 ‰) is the primary source of intermediate/deep water masses in the basin. As this water flows southward and ages, δ13C values decrease and ɛNd values increase; however, additional chemical changes at several sites require mixing with contributions from several additional water masses. Lower ɛNd ( -10) and higher δ13C ( 1.9 ‰) values in the deep NW part of the basin indicate proximal contributions from a region draining old continental crust, potentially representing deep convection following opening of the Labrador Sea. In the deep NE Iberian Basin, higher ɛNd ( -7) and lower δ13C ( 0.8 ‰) during the Campanian suggest mixing with a Tethyan source (ɛNd -7 and δ13C 0.1 ‰) whose importance decreased with restriction of that gateway in the Maastrichtian. Data from bathyal sites suggest additional mixing. In the SE Cape Verde region, observed ɛNd variations from -10 in the Campanian to -13 and -12 in the early and late Maastrichtian, respectively, may record variations in output rates of Tethyan and/or NCW sources and Demerara Bottom Water (ɛNd -16), a proposed warm saline intermediate water mass formed in shallow, equatorial seas. Pacific inflow through the Caribbean gateway impacts intermediate sites at Blake Nose (ɛNd values -8), particularly the shallowest site during the late

Effect of ozonation of swimming pool water on formation of volatile disinfection by-products - A laboratory study

DEFF Research Database (Denmark)

Hansen, Kamilla Marie Speht; Spiliotopoulou, Aikaterini; Cheema, Waqas Akram

2016-01-01

Ozonation experiments were performed using unchlorinated tap water used for filling municipal swimming pools, actual pool water and pool water polluted by addition of fresh tap water and artificial body fluid to evaluate ozone kinetics and water quality effects on formation of volatile disinfecti...

Organic chloramines in chlorine-based disinfected water systems: A critical review.

Science.gov (United States)

How, Zuo Tong; Kristiana, Ina; Busetti, Francesco; Linge, Kathryn L; Joll, Cynthia A

2017-08-01

This paper is a critical review of current knowledge of organic chloramines in water systems, including their formation, stability, toxicity, analytical methods for detection, and their impact on drinking water treatment and quality. The term organic chloramines may refer to any halogenated organic compounds measured as part of combined chlorine (the difference between the measured free and total chlorine concentrations), and may include N-chloramines, N-chloramino acids, N-chloraldimines and N-chloramides. Organic chloramines can form when dissolved organic nitrogen or dissolved organic carbon react with either free chlorine or inorganic chloramines. They are potentially harmful to humans and may exist as an intermediate for other disinfection by-products. However, little information is available on the formation or occurrence of organic chloramines in water due to a number of challenges. One of the biggest challenges for the identification and quantification of organic chloramines in water systems is the lack of appropriate analytical methods. In addition, many of the organic chloramines that form during disinfection are unstable, which results in difficulties in sampling and detection. To date research has focussed on the study of organic monochloramines. However, given that breakpoint chlorination is commonly undertaken in water treatment systems, the formation of organic dichloramines should also be considered. Organic chloramines can be formed from many different precursors and pathways. Therefore, studying the occurrence of their precursors in water systems would enable better prediction and management of their formation. Copyright © 2017. Published by Elsevier B.V.

Disinfection Methods for Swimming Pool Water: Byproduct Formation and Control

Directory of Open Access Journals (Sweden)

Huma Ilyas

2018-06-01

Full Text Available This paper presents a comprehensive and critical comparison of 10 disinfection methods of swimming pool water: chlorination, electrochemically generated mixed oxidants (EGMO, ultraviolet (UV irradiation, UV/chlorine, UV/hydrogen peroxide (H2O2, UV/H2O2/chlorine, ozone (O3/chlorine, O3/H2O2/chlorine, O3/UV and O3/UV/chlorine for the formation, control and elimination of potentially toxic disinfection byproducts (DBPs: trihalomethanes (THMs, haloacetic acids (HAAs, haloacetonitriles (HANs, trihaloacetaldehydes (THAs and chloramines (CAMs. The statistical comparison is carried out using data on 32 swimming pools accumulated from the reviewed studies. The results indicate that O3/UV and O3/UV/chlorine are the most promising methods, as the concentration of the studied DBPs (THMs and HANs with these methods was reduced considerably compared with chlorination, EGMO, UV irradiation, UV/chlorine and O3/chlorine. However, the concentration of the studied DBPs including HAAs and CAMs remained much higher with O3/chlorine compared with the limits set by the WHO for drinking water quality. Moreover, the enhancement in the formation of THMs, HANs and CH with UV/chlorine compared with UV irradiation and the increase in the level of HANs with O3/UV/chlorine compared with O3/UV indicate the complexity of the combined processes, which should be optimized to control the toxicity and improve the quality of swimming pool water.

On the mechanism of water cluster-ion formation in carbon dioxide

International Nuclear Information System (INIS)

Warneck, P.; Rakshit, A.B.

1981-01-01

A drift chamber mass spectrometer has been used to study the formation of water cluster-ions in carbon dioxide containing traces of water vapour. The dominant reaction sequences were identified up to the fourth generation of daughter ions starting with CO 2 + . The subsequent reaction mechanism remains uncertain and several possibilities are discussed. The final ions are H 3 O + H 2 O and H 3 O + (H 2 O) 2 . The significance of the reaction schemes to the radiation chemistry of carbon dioxide is pointed out. (orig.)

Numerical analysis of wellbore instability in gas hydrate formation during deep-water drilling

Science.gov (United States)

Zhang, Huaiwen; Cheng, Yuanfang; Li, Qingchao; Yan, Chuanliang; Han, Xiuting

2018-02-01

Gas hydrate formation may be encountered during deep-water drilling because of the large amount and wide distribution of gas hydrates under the shallow seabed of the South China Sea. Hydrates are extremely sensitive to temperature and pressure changes, and drilling through gas hydrate formation may cause dissociation of hydrates, accompanied by changes in wellbore temperatures, pore pressures, and stress states, thereby leading to wellbore plastic yield and wellbore instability. Considering the coupling effect of seepage of drilling fluid into gas hydrate formation, heat conduction between drilling fluid and formation, hydrate dissociation, and transformation of the formation framework, this study established a multi-field coupling mathematical model of the wellbore in the hydrate formation. Furthermore, the influences of drilling fluid temperatures, densities, and soaking time on the instability of hydrate formation were calculated and analyzed. Results show that the greater the temperature difference between the drilling fluid and hydrate formation is, the faster the hydrate dissociates, the wider the plastic dissociation range is, and the greater the failure width becomes. When the temperature difference is greater than 7°C, the maximum rate of plastic deformation around the wellbore is more than 10%, which is along the direction of the minimum horizontal in-situ stress and associated with instability and damage on the surrounding rock. The hydrate dissociation is insensitive to the variation of drilling fluid density, thereby implying that the change of the density of drilling fluids has a minimal effect on the hydrate dissociation. Drilling fluids that are absorbed into the hydrate formation result in fast dissociation at the initial stage. As time elapses, the hydrate dissociation slows down, but the risk of wellbore instability is aggravated due to the prolonged submersion in drilling fluids. For the sake of the stability of the wellbore in deep-water

Reactivity of Criegee Intermediates toward Carbon Dioxide.

Science.gov (United States)

Lin, Yen-Hsiu; Takahashi, Kaito; Lin, Jim Jr-Min

2018-01-04

Recent theoretical work by Kumar and Francisco suggested that the high reactivity of Criegee intermediates (CIs) could be utilized for designing efficient carbon capture technologies. Because the anti-CH 3 CHOO + CO 2 reaction has the lowest barrier in their study, we chose to investigate it experimentally. We probed anti-CH 3 CHOO with its strong UV absorption at 365 nm and measured the rate coefficient to be ≤2 × 10 -17 cm 3 molecule -1 s -1 at 298 K, which is consistent with our theoretical value of 2.1 × 10 -17 cm 3  molecule -1 s -1 at the QCISD(T)/CBS//B3LYP/6-311+G(2d,2p) level but inconsistent with their results obtained at the M06-2X/aug-cc-pVTZ level, which tends to underestimate the barrier heights. The experimental result indicates that the reaction of a Criegee intermediate with atmospheric CO 2 (400 ppmv) would be inefficient (k eff < 0.2 s -1 ) and cannot compete with other decay processes of Criegee intermediates like reactions with water vapor (∼10 3 s -1 ) or thermal decomposition (∼10 2 s -1 ).

Water isotopic characterization of hypersaline formation of a petroleum field Reconcavo basin, Brazil

International Nuclear Information System (INIS)

Teles, Danilo Ribeiro de Sa; Azevedo, Antonio Expedito Gomes de

2010-01-01

Formation water is the water present in reservoir rock pores, produced together with petroleum. Usually it is hyper saline with concentrations that can be higher than 250 g/l of dissolved solids. The concentration of the dissolved elements and the isotopic composition of the water and of some of the dissolved elements can be excellent tracers to study the dynamic of underground fluid flux, the mixing of distinct sources and the origin of salinization of these waters. This work reports the isotopic composition (δ 2 H , δ 18 O) and electrical conductivity (EC) of formation waters from 10 wells of a petroleum field of the Reconcavo Basin, looking for their evolution, interaction with the minerals and rocks and reservoir interconnection. The samples have electric conductivity ranging from 84 to 137 mS/cm, with conductivity increasing with depth of production zone. It is observed an enrichment of deuterium and oxygen-18 with the depth of production zone, probably due to water-rock interactions that were probably increased by higher temperatures of the deeper levels and longer residence times. The samples from the production zone between 1450 to 1520 m, drained by 7 of the 10 wells sampled, show a small range in isotopic composition and in electric conductivity, indicating homogeneity in this level of the reservoir. In the shallow level of 450 m the values of δ 2 H , δ 18 O and EC are lower, with isotopic composition similar to the oceanic water, possibly representing the original water that entered the reservoir during the sedimentation of the basin. (author)

The study of interrelationship between raw water quality parameters, chlorine demand and the formation of disinfection by-products

Science.gov (United States)

Abdullah, Md. Pauzi; Yee, Lim Fang; Ata, Sadia; Abdullah, Abass; Ishak, Basar; Abidin, Khairul Nidzham Zainal

Disinfection is the most crucial process in the treatment of drinking water supply and is the final barrier against bacteriological impurities in drinking water. Chlorine is the primary disinfectant used in the drinking water treatment process throughout Malaysia. However, the occurrence of various disinfection by-products such as trihalomethanes (THM) and haloacetic acids created a major issue on the potential health hazards which may pose adverse health effects in both human and animals. To simulate real water treatment conditions and to represent the conditions inherent in a tropical country, this study was performed at an urbanized water treatment plant with a daily production of about 549,000 m 3 of treated water. The purpose of this work is to examine the relationship between the water quality parameters in the raw water with chlorine demand and the formation of disinfection by-products. This study also investigated the possibility of the statistical model applications for the prediction of chlorine demand and the THM formation. Two models were developed to estimate the chlorine demand and the THM formation. For the statistical evaluation, correlation and simple linear regression analysis were conducted using SPSS. The results of Kolmogorov-Smirnov test for the estimation of goodness-of-fit of the dependent variables of the models to the normal distribution showed that all the dependent variables followed the normal distribution at significance level of 0.05. Good linear correlations were observed between the independent parameters and formation of THM and the chlorine demand. This study also revealed that ammonia and the specific ultraviolet absorbent (SUVA) were the function of chlorine consumption in the treatment process. Chlorine dosage and SUVA increase the yield of THM. Chlorine demand and THM formation was moderately sensitive, but significant to the pH. The level of significance ( α) for the statistical tests and the inclusion of a variable in the

Investigation of potential water inflow into a ventilated tunnel of the proposed low/intermediate-level waste repository in Switzerland

Energy Technology Data Exchange (ETDEWEB)

Eugster, S.M. [Swiss Federal Institute of Technology, Zurich (Switzerland); Senger, R.K. [INTERA Inc., Austin, TX (United States)

1995-03-01

Design calculations of two-phase flow phenomena associated with the construction and ventilation of a tunnel were investigated to estimate the potential water inflow through discrete water-conducting features (WCFs) into the tunnel. The physical processes that were considered in numerical simulations include the transient propagation of the pressure decline into the formation (Valanginian Marl, initially fully saturated, no dissolved gas) as a result of the tunnel construction. Ventilation of the tunnel results in a reduction in relative humidity of the tunnel air which, in turn, causes evaporation of water at the tunnel wall and the potential development of an unsaturated zone into the formation. The objective of this study is to investigate under what conditions the tunnel wall appears wet or dry, i.e. whether WCFs can be identified in a ventilated tunnel by mapping water inflow patterns. The simulation results indicate that inflow to the tunnel decreases with time approaching steady state flow rates under single-phase flow conditions, which is lower than the evaporation rate. The water inflow rate decreased more rapidly for a first model scenario (WCF parallel to the tunnel axis), caused by linear flow through the WCF, than for a second model scenario (WCF perpendicular to the tunnel axis), characterized by radial flow toward the tunnel. Similarly, the desaturation zone extends farther into the WCF under linear flow than under radial flow.

Water-in-oil emulsions results of formation studies and applicability to oil spill modelling

International Nuclear Information System (INIS)

Fingas, Merv; Fieldhouse, Ben; Mullin, Joe

1999-01-01

This paper summarises studies of water-in-oil emulsions, their stability, and modelling of their formation. Studies show that water-in-oil emulsions might be characterised into three categories (stable, mesostable and unstable). These categories were established by visual appearance, elasticity and viscosity difference. It was also shown that water content was not an important factor. A fourth category of water-in-oil exists, that of water entrainment, which is not an emulsion. Water-in-oil emulsions made from crude oils have different classes of stabilities as a result of the asphaltene and resin contents. The differences in the emulsion types are readily distinguished both by their rheological properties, and simply by appearance. The apparent viscosity of a stable emulsion at a shear rate of one reciprocal second, is at least three orders-of-magnitude greater than the starting oil. An unstable emulsion usually has a viscosity no more than one order-of-magnitude greater than that of the starting oil. A stable emulsion has a significant elasticity, whereas an unstable emulsion does not. Stable emulsions have sufficient asphaltenes (>∼7%) to establish films of these compounds around water droplets. Mesostable emulsions have insufficient asphaltenes to render them completely stable. Stability is achieved by visco-elastic retention of water and secondarily by the presence of asphaltene or resin films. Mesostable emulsions display apparent viscosities of about 80-600 times that of the starting oil and true viscosities of 20-200 times that of the starting oil. Mesostable emulsions have an asphaltene and resin content greater than 3%. Entrained water occurs when a viscous oil retains larger water droplets, but conditions are not suitable for the formation of an emulsion. Entrained water may have a viscosity that is similar or slightly greater (∼ 2-10 times) than the starting oil. It was found that emulsion formation occurs at a threshold energy, however this energy

Hydrozirconation of lithium alkynylselenolate anions. Generation and reactions of alpha-zirconated vinyl selenide intermediates

Science.gov (United States)

Dabdoub; Begnini; Guerrero; Baroni

2000-01-14

Lithium alkynylselenolate anions react completely with 1.0 equiv of Cp(2)Zr(H)Cl in THF at room temperature to give exclusively the alpha-zirconated vinylselenolate intermediates 23-27, which by treatment with an alkyl halide afforded the alpha-zirconated vinyl alkylselenide intermediates 29-33. Reaction of 29-33 with butyltellurenyl bromide results in the formation of ketene telluro(seleno) acetals 35-39 with total control of the regio- and stereochemistry. The synthetic utility of the ketene telluro(seleno) acetals obtained here was demonstrated by reaction of 36 with butyllithium. This promotes the exclusive and stereospecific removal of the tellurium moiety and enables formation of the corresponding selenium-containing allylic alcohol of type 44, alpha-(alkylseleno)-alpha,beta-unsaturated aldehyde 45, ester 46, or carboxylic acid 47, after reaction with different types of electrophiles.

Formation of large target residues in intermediate energy nuclear collisions

International Nuclear Information System (INIS)

Loveland, W.; Aleklett, K.; Sihver, L.; Xu, Z.; Seaborg, G.T.

1987-04-01

We have used radiochemical techniques to measure the yields, angular distributions and velocity spectra of the large (A/sub frag/ ≥ 2/3 A/sub tgt/) target residues from the fragmentation of 197 Au by intermediate energy 12 C, 20 Ne, 32 S, 40 Ar, 84 Kr, and 139 La projectiles. The fragment moving frame angular distributions are asymmetric for the lighter projectiles (C-Ar). The fragment velocity spectra are Maxwellian for the Kr induced reactions and non-Maxwellian for the reactions induced by the lighter ions. We interpret these results in terms of a change in the dominant fragment production mechanism(s) from one(s) involving a fast non-equilibrium process for the lighter ions to a slow, equilibrium process for Kr. Comparison of the measured yields and angular distributions with calculations made using a Boltzmann transport equation with appropriate modifications for Pauli blocking, etc., show excellent agreement between data and theory. 12 refs., 12 figs

An analysis of system pressure and temperature distribution in self-pressurizer of SMART considering thermal stratification at intermediate cavity

Energy Technology Data Exchange (ETDEWEB)

Kang, Yeon Moon; Lee, Doo Jeong; Yoon, Ju Hyun; Kim, Hwan Yeol [Korea Atomic Energy Research Institute, Taejon (Korea)

1999-03-01

Because the pressurizer is in reactor vessel, the heat transfer from primary water would increase the temperatures of fluids in pressurizer to same temperature of hotleg, if no cooling equipment were supplied. Thus, heat exchanger and thermal insulator are needed to minimize heat transferred from primary water and to remove heat in pressurizer. The temperatures in cavities of pressurizer for normal operation are 70 deg C and 74 deg C for intermediate and end cavity, respectively, which considers the solubility of nitrogen gas in water. Natural convection is the mechanism of heat balance in pressurizer of SMART. In SMART, the heat exchanger in pressurizer is placed in lower part of intermediate cavity, so the heat in upper part of intermediate cavity can't be removed adequately and it can cause thermal stratification. If thermal stratification occurred, it increases heat transfers to nitrogen gas and system pressure increases as the result. Thus, proper evaluation of those effects on system pressure and ways to mitigate thermal stratification should be established. This report estimates the system pressure and temperatures in cavities of pressurizer with considering thermal stratification in intermediate cavity. The system pressure and temperatures for each cavities considered size of wet thermal insulator, temperature of upper plate of reactor vessel, parameters of heat exchanger in intermediate cavity such as flow rate and temperature of cooling water, heat transfer area, effective tube height, and location of cooling tube. In addition to the consideration of thermal stratification thermal mixing of all water in intermediate cavity also considered and compared in this report. (author). 6 refs., 60 figs., 2 tabs.

Organic substances in produced and formation water from unconventional natural gas extraction in coal and shale

Science.gov (United States)

Orem, William H.; Tatu, Calin A.; Varonka, Matthew S.; Lerch, Harry E.; Bates, Anne L.; Engle, Mark A.; Crosby, Lynn M.; McIntosh, Jennifer

2014-01-01

Organic substances in produced and formation water from coalbed methane (CBM) and gas shale plays from across the USA were examined in this study. Disposal of produced waters from gas extraction in coal and shale is an important environmental issue because of the large volumes of water involved and the variable quality of this water. Organic substances in produced water may be environmentally relevant as pollutants, but have been little studied. Results from five CBM plays and two gas shale plays (including the Marcellus Shale) show a myriad of organic chemicals present in the produced and formation water. Organic compound classes present in produced and formation water in CBM plays include: polycyclic aromatic hydrocarbons (PAHs), heterocyclic compounds, alkyl phenols, aromatic amines, alkyl aromatics (alkyl benzenes, alkyl biphenyls), long-chain fatty acids, and aliphatic hydrocarbons. Concentrations of individual compounds range from gas shale unimpacted by production chemicals have a similar range of compound classes as CBM produced water, and TOC levels of about 8 mg/L. However, produced water from the Marcellus Shale using hydraulic fracturing has TOC levels as high as 5500 mg/L and a range of added organic chemicals including, solvents, biocides, scale inhibitors, and other organic chemicals at levels of 1000 s of μg/L for individual compounds. Levels of these hydraulic fracturing chemicals and TOC decrease rapidly over the first 20 days of water recovery and some level of residual organic contaminants remain up to 250 days after hydraulic fracturing. Although the environmental impacts of the organics in produced water are not well defined, results suggest that care should be exercised in the disposal and release of produced waters containing these organic substances into the environment because of the potential toxicity of many of these substances.

Controls of Ca/Mg/Fe activity ratios in pore water chemistry models of the Callovian-Oxfordian clay formation

International Nuclear Information System (INIS)

Lerouge, C.; Grangeon, S.; Wille, G.; Flehoc, C.; Gailhanou, H.; Gaucher, E.C.; Tournassat, C.; Vinsot, A.; Made, B.; Altmann, S.

2013-01-01

In the pore water chemistry model of the Callovian-Oxfordian clay formation, the divalent cations Ca, Mg, and Fe are controlled by equilibrium reactions with pure carbonates: calcite for Ca, dolomite for Mg, and siderite for Fe. Results of a petrological study and computing of the Ca/Mg and Ca/Fe activity ratios based on natural pore water chemistry provide evidence that equilibrium with pure calcite and pure dolomite is a reasonable assumption for undisturbed pore waters; on the other hand, siderite cannot be considered at equilibrium with pore waters at the formation scale. (authors)

Controls of Ca/Mg/Fe activity ratios in pore water chemistry models of the Callovian-Oxfordian clay formation

Energy Technology Data Exchange (ETDEWEB)

Lerouge, C.; Grangeon, S.; Wille, G.; Flehoc, C.; Gailhanou, H.; Gaucher, E.C.; Tournassat, C. [BRGM av. Claude Guillemin BP6009 45060 Orleans cedex 2 (France); Vinsot, A. [ANDRA Meuse/Haute-Marne Underground research Laboratory (URL), RD 960, 55290 Bure (France); Made, B.; Altmann, S. [ANDRA - Parc de la Croix Blanche, 1-7 rue Jean Monnet, 92298 Chatenay-Malabry Cedex (France)

2013-07-01

In the pore water chemistry model of the Callovian-Oxfordian clay formation, the divalent cations Ca, Mg, and Fe are controlled by equilibrium reactions with pure carbonates: calcite for Ca, dolomite for Mg, and siderite for Fe. Results of a petrological study and computing of the Ca/Mg and Ca/Fe activity ratios based on natural pore water chemistry provide evidence that equilibrium with pure calcite and pure dolomite is a reasonable assumption for undisturbed pore waters; on the other hand, siderite cannot be considered at equilibrium with pore waters at the formation scale. (authors)

Microbial analysis of in situ biofilm formation in drinking water distribution systems: implications for monitoring and control of drinking water quality.

Science.gov (United States)

Douterelo, Isabel; Jackson, M; Solomon, C; Boxall, J

2016-04-01

Biofilm formation in drinking water distribution systems (DWDS) is influenced by the source water, the supply infrastructure and the operation of the system. A holistic approach was used to advance knowledge on the development of mixed species biofilms in situ, by using biofilm sampling devices installed in chlorinated networks. Key physico-chemical parameters and conventional microbial indicators for drinking water quality were analysed. Biofilm coverage on pipes was evaluated by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The microbial community structure, bacteria and fungi, of water and biofilms was assessed using pyrosequencing. Conventional wisdom leads to an expectation for less microbial diversity in groundwater supplied systems. However, the analysis of bulk water showed higher microbial diversity in groundwater site samples compared with the surface water site. Conversely, higher diversity and richness were detected in biofilms from the surface water site. The average biofilm coverage was similar among sites. Disinfection residual and other key variables were similar between the two sites, other than nitrates, alkalinity and the hydraulic conditions which were extremely low at the groundwater site. Thus, the unexpected result of an exceptionally low diversity with few dominant genera (Pseudomonas and Basidiobolus) in groundwater biofilm samples, despite the more diverse community in the bulk water, is attributed to the low-flow hydraulic conditions. This finding evidences that the local environmental conditions are shaping biofilm formation, composition and amount, and hence managing these is critical for the best operation of DWDS to safeguard water quality.

Single-Step Syngas-to-Distillates (S2D) Synthesis via Methanol and Dimethyl Ether Intermediates: Final Report

Energy Technology Data Exchange (ETDEWEB)

Dagle, Robert A.; Lebarbier, Vanessa MC; Lizarazo Adarme, Jair A.; King, David L.; Zhu, Yunhua; Gray, Michel J.; Jones, Susanne B.; Biddy, Mary J.; Hallen, Richard T.; Wang, Yong; White, James F.; Holladay, Johnathan E.; Palo, Daniel R.

2013-11-26

The objective of the work was to enhance price-competitive, synthesis gas (syngas)-based production of transportation fuels that are directly compatible with the existing vehicle fleet (i.e., vehicles fueled by gasoline, diesel, jet fuel, etc.). To accomplish this, modifications to the traditional methanol-to-gasoline (MTG) process were investigated. In this study, we investigated direct conversion of syngas to distillates using methanol and dimethyl ether intermediates. For this application, a Pd/ZnO/Al2O3 (PdZnAl) catalyst previously developed for methanol steam reforming was evaluated. The PdZnAl catalyst was shown to be far superior to a conventional copper-based methanol catalyst when operated at relatively high temperatures (i.e., >300°C), which is necessary for MTG-type applications. Catalytic performance was evaluated through parametric studies. Process conditions such as temperature, pressure, gas-hour-space velocity, and syngas feed ratio (i.e., hydrogen:carbon monoxide) were investigated. PdZnAl catalyst formulation also was optimized to maximize conversion and selectivity to methanol and dimethyl ether while suppressing methane formation. Thus, a PdZn/Al2O3 catalyst optimized for methanol and dimethyl ether formation was developed through combined catalytic material and process parameter exploration. However, even after compositional optimization, a significant amount of undesirable carbon dioxide was produced (formed via the water-gas-shift reaction), and some degree of methane formation could not be completely avoided. Pd/ZnO/Al2O3 used in combination with ZSM-5 was investigated for direct syngas-to-distillates conversion. High conversion was achieved as thermodynamic constraints are alleviated when methanol and dimethyl are intermediates for hydrocarbon formation. When methanol and/or dimethyl ether are products formed separately, equilibrium restrictions occur. Thermodynamic relaxation also enables the use of lower operating pressures than what

Environmental effects of disposal of intermediate-level wastes by shale fracturing

International Nuclear Information System (INIS)

Weeren, H.O.

1978-01-01

Shale fracturing is a process currently being used at the Oak Ridge National Laboratory for the permanent disposal of locally generated, intermediate-level waste solutions. In this process, the waste is mixed with a solids blend of cement and other additives; the resulting grout is then injected into an impermeable shale formation at a depth of 700 to 1000 ft. A few hours after completion of the injection, the grout sets and the radioactive waste are fixed in the shale formation. An analysis of environmental effects of normal operation and possible accident situations is discussed

Freshening of Antarctic Intermediate Water in the South Atlantic Ocean in 2005–2014

Directory of Open Access Journals (Sweden)

W. Yao

2017-07-01

Full Text Available Basin-scale freshening of Antarctic Intermediate Water (AAIW is reported to have occurred in the South Atlantic Ocean during the period from 2005 to 2014, as shown by the gridded monthly means of the Array for Real-time Geostrophic Oceanography (Argo data. This phenomenon was also revealed by two repeated transects along a section at 30° S, performed during the World Ocean Circulation Experiment Hydrographic Program. Freshening of the AAIW was compensated for by a salinity increase of thermocline water, indicating a hydrological cycle intensification. This was supported by the precipitation-minus-evaporation change in the Southern Hemisphere from 2000 to 2014. Freshwater input from atmosphere to ocean surface increased in the subpolar high-precipitation region and vice versa in the subtropical high-evaporation region. Against the background of hydrological cycle changes, a decrease in the transport of Agulhas Leakage (AL, which was revealed by the simulated velocity field, was proposed to be a contributor to the associated freshening of AAIW. Further calculation showed that such a decrease could account for approximately 53 % of the observed freshening (mean salinity reduction of about 0.012 over the AAIW layer. The estimated variability of AL was inferred from a weakening of wind stress over the South Indian Ocean since the beginning of the 2000s, which would facilitate freshwater input from the source region. The mechanical analysis of wind data here was qualitative, but it is contended that this study would be helpful to validate and test predictably coupled sea–air model simulations.

Electrochemical and Spectroscopic Study of Mononuclear Ruthenium Water Oxidation Catalysts: A Combined Experimental and Theoretical Investigation

KAUST Repository

de Ruiter, J. M.

2016-09-20

One of the key challenges in designing light-driven artificial photosynthesis devices is the optimization of the catalytic water oxidation process. For this optimization it is crucial to establish the catalytic mechanism and the intermediates of the catalytic cycle, yet a full description is often difficult to obtain using only experimental data. Here we consider a series of mononuclear ruthenium water oxidation catalysts of the form [Ru(cy)(L)(H2O)](2+) (cy = p-cymene, L = 2,2\\'-bipyridine and its derivatives). The proposed catalytic cycle and intermediates are examined using density functional theory (DFT), radiation chemistry, spectroscopic techniques, and electrochemistry to establish the water oxidation mechanism. The stability of the catalyst is investigated using online electrochemical mass spectrometry (OLEMS). The comparison between the calculated absorption spectra of the proposed intermediates with experimental spectra, as well as free energy calculations with electrochemical data, provides strong evidence for the proposed pathway: a water oxidation catalytic cycle involving four proton-coupled electron transfer (PCET) steps. The thermodynamic bottleneck is identified as the third PCET step, which involves O-O bond formation. The good agreement between the optical and thermodynamic data and DFT predictions further confirms the general applicability of this methodology as a powerful tool in the characterization of water oxidation catalysts and for the interpretation of experimental observables.

Electrocatalytic Water Oxidation by a Homogeneous Copper Catalyst Disfavors Single-Site Mechanisms.

Science.gov (United States)

Koepke, Sara J; Light, Kenneth M; VanNatta, Peter E; Wiley, Keaton M; Kieber-Emmons, Matthew T

2017-06-28

Deployment of solar fuels derived from water requires robust oxygen-evolving catalysts made from earth abundant materials. Copper has recently received much attention in this regard. Mechanistic parallels between Cu and single-site Ru/Ir/Mn water oxidation catalysts, including intermediacy of terminal Cu oxo/oxyl species, are prevalent in the literature; however, intermediacy of late transition metal oxo species would be remarkable given the high d-electron count would fill antibonding orbitals, making these species high in energy. This may suggest alternate pathways are at work in copper-based water oxidation. This report characterizes a dinuclear copper water oxidation catalyst, {[(L)Cu(II)] 2 -(μ-OH) 2 }(OTf) 2 (L = Me 2 TMPA = bis((6-methyl-2-pyridyl)methyl)(2-pyridylmethyl)amine) in which water oxidation proceeds with high Faradaic efficiency (>90%) and moderate rates (33 s -1 at ∼1 V overpotential, pH 12.5). A large kinetic isotope effect (k H /k D = 20) suggests proton coupled electron transfer in the initial oxidation as the rate-determining step. This species partially dissociates in aqueous solution at pH 12.5 to generate a mononuclear {[(L)Cu(II)(OH)]} + adduct (K eq = 0.0041). Calculations that reproduce the experimental findings reveal that oxidation of either the mononuclear or dinuclear species results in a common dinuclear intermediate, {[LCu(III)] 2 -(μ-O) 2 } 2+ , which avoids formation of terminal Cu(IV)═O/Cu(III)-O • intermediates. Calculations further reveal that both intermolecular water nucleophilic attack and redox isomerization of {[LCu(III)] 2 -(μ-O) 2 } 2+ are energetically accessible pathways for O-O bond formation. The consequences of these findings are discussed in relation to differences in water oxidation pathways between Cu catalysts and catalysts based on Ru, Ir, and Mn.

Contribution of natural tracers for understanding transfers through argillaceous formations

International Nuclear Information System (INIS)

Bensenouci, F.

2010-01-01

This study is part of a research programme conducted by IRSN on the safety of deep geological disposal of high level and intermediate long-lived radioactive wastes. It more especially concerns the geological medium considered as a full component of the multi-barrier concept proposed by Andra for a deep repository. Indeed, the Callovo-Oxfordian argillite of the Paris Basin, in the east of France, is being investigated by Andra as a potential host rock for this repository. Performance assessment of this natural barrier is based on the knowledge of its confinement properties and therefore on phenomena possibly involved in the mass transport of radionuclides. In this context, this work aimed at studying the distribution of tracers naturally present in pore waters obtained from boreholes having crossed Mesozoic sedimentary series involving impervious and compacted clay rocks in the East (Andra borehole, EST433) and south of France (IRSN boreholes). Radial diffusion and vapour exchange methods were used to calculate the concentrations and diffusion parameters of the studied tracers. In Tournemire formations, the different profiles describe a curved shapes attributed to a diffusive exchange between the argillite pore water and the surrounding aquifers. Concerning the Mesozoic formations crossed by EST433, the study of the different profiles confirms the diffusion as the dominant transport mechanism in the Callovo-Oxfordian formation, and permits identifying the transport processes in the whole studied column from the Oxfordian formations down to the Liassic one. This study also helps to identify the Liassic formations as a major source of salinity of the Dogger aquifer

The effect of inorganic precursors on disinfection byproduct formation during UV-chlorine/chloramine drinking water treatment.

Science.gov (United States)

Lyon, Bonnie A; Dotson, Aaron D; Linden, Karl G; Weinberg, Howard S

2012-10-01

Ultraviolet (UV) disinfection is being increasingly used in drinking water treatment. It is important to understand how its application to different types of water may influence finished water quality, particularly as anthropogenic activity continues to impact the quality of source waters. The objective of this study was to evaluate the effect of inorganic precursors on the formation of regulated and unregulated disinfection byproducts (DBPs) during UV irradiation of surface waters when combined with chlorination or chloramination. Samples were collected from three drinking water utilities supplied by source waters with varying organic and inorganic precursor content. The filtered samples were treated in the laboratory with a range of UV doses delivered from low pressure (LP, UV output at 253.7 nm) and medium pressure (MP, polychromatic UV output 200-400 nm) mercury lamps followed by chlorination or chloramination, in the presence and absence of additional bromide and nitrate. The regulated trihalomethanes and haloacetic acids were not affected by UV pretreatment at disinfection doses (40-186 mJ/cm²). With higher doses (1000 mJ/cm²), trihalomethane formation was increased 30-40%. While most effects on DBPs were only observed with doses much higher than typically used for UV disinfection, there were some effects on unregulated DBPs at lower doses. In nitrate-spiked samples (1-10 mg N/L), chloropicrin formation doubled and increased three- to six-fold with 40 mJ/cm² MP UV followed by chloramination and chlorination, respectively. Bromopicrin formation was increased in samples containing bromide (0.5-1 mg/L) and nitrate (1-10 mg N/L) when pretreated with LP or MP UV (30-60% with 40 mJ/cm² LP UV and four- to ten-fold increase with 40 mJ/cm² MP UV, after subsequent chlorination). The formation of cyanogen chloride doubled and increased three-fold with MP UV doses of 186 and 1000 mJ/cm², respectively, when followed by chloramination in nitrate-spiked samples but

Electrolysis of water on (oxidized) metal surfaces

DEFF Research Database (Denmark)

Rossmeisl, Jan; Logadottir, Ashildur; Nørskov, Jens Kehlet

2005-01-01

Density functional theory calculations are used as the basis for an analysis of the electrochemical process, where by water is split to form molecular oxygen and hydrogen. We develop a method for obtaining the thermochemistry of the electrochemical water splitting process as a function of the bias...... directly from the electronic structure calculations. We consider electrodes of Pt(111) and Au(111) in detail and then discuss trends for a series of different metals. We show that the difficult step in the water splitting process is the formation of superoxy-type (OOH) species on the surface...... by the splitting of a water molecule on top an adsorbed oxygen atom. One conclusion is that this is only possible on metal surfaces that are (partly) oxidized. We show that the binding energies of the different intermediates are linearly correlated for a number of metals. In a simple analysis, where the linear...

Corrosion behavior of construction materials for intermediate temperature steam electrolysers

DEFF Research Database (Denmark)

Nikiforov, Aleksey; Petrushina, Irina; Jensen, Jens Oluf

2013-01-01

Different corrosion resistant stainless steels, nickel-based alloys, pure nickel, Ta-coated stainless steel (AISI 316L), niobium, platinum and gold rods were evaluated as possible materials for use in the intermediate temperature (200-400 °C) acidic water electrolysers. The corrosion resistance w...

The gas chimney formation during the steam explosion premixing phase

International Nuclear Information System (INIS)

Leskovar, M.

2001-01-01

The crucial part in isothermal premixing experiment simulation is the correct prediction of the gas chimney, which forms when the spheres penetrate into water. The first simulation results with the developed original combined multiphase model showed that the gas chimney starts to close at the wrong place at the top of the chimney and not in the middle, like it was observed in the experiments. To find the physical explanation for this identified weakness of our numerical model a comprehensive parametric analysis (mesh size, initial water-air surface thickness, water density, momentum coupling starting position) has been performed. It was established that the reason for the unphysical gas chimney closing at the top could be the gradual air-water density transition in the experiment model, since there is due to the finite differences description always a transition layer with intermediate phases density over the pure water phase. It was shown that this difference between our numerical model and the experiment can be somewhat compensated if the spheres interfacial drag coefficient at the upmost mesh plane of the unphysical air-water transition layer is artificially risen. On this way a more correct gas chimney formation can be obtained.(author)

Different aspects of nuclear physics from low energies up to intermediate energies

International Nuclear Information System (INIS)

Lallouet, Y.

2011-12-01

This study focuses on different aspects of nuclear physics from low energies to intermediate ones. For the low energies, the nuclear matter is essentially constituted from interacting nucleons. Part I is on the fusion-fission of super-heavy elements, while Part II is on the Skyrme interactions associated sum rules. In the case of the intermediate energies, where the nuclear matter is considered as being an hadronic phase mainly constituted from pions, Part III is focused on nuclear matter relativistic hydrodynamics with spontaneous chiral symmetry breaking. In Part I, the formation and the deexcitation of super-heavy nuclei are being studied. The memory effect must be taken into consideration within the super-heavy nuclei formation dynamics. Therefore we analyzed the formation of compound nuclei including the memory effects. As for the intermediate memory effects some oscillations appear, which is very different from the Markovian dynamics. For super-heavy nuclei deexcitation, the existence of isomeric state within the potential barrier cannot explain the results of experiments performed at GANIL with the crystal blocking technique, and this despite of the fact that it modifies the deexcitation dynamics and increases the fission time. However, this latter study could be useful for the study of the actinides fission. In Part II, the phenomenological Skyrme effective interactions-associated M 1 and M 3 sum rules are being calculated based on their intrinsic definitions. We identify then M 1 up to the tensorial level and M 3 with central potential. In Part III, as for the hadronic matter hydrodynamics being applied to heavy ions collisions, and as a first approach only, we can neglect spontaneous chiral symmetry but certainly not the dissipative impact. (author)

Formation of grooves during the breakdown of a coal block by a water jet

Energy Technology Data Exchange (ETDEWEB)

Shavlovskii, S.S.

1979-02-01

A description is given of a method of coal excavation which provides for the initial formation of a grooved slit along the width of the opening equal in height to the diameter of the sinkhole. The formation of a groove in the coal block and the excavation of coal by water jets using the grooved crater method are illustrated in diagrams. Data are given on changes in the performance of the hydraulic jet in coal excavation in relation to the distance between the nozzle and the face and at given pressures in front of the nozzle. Functional relationships were mathematically constructed for the performance of the water jet in dimensionless coordinates. Data are also given on the comparative performance of a water jet when coal is excavated by the grooved funnel method and by hydraulic fracturing. The analytical computations indicate that the hydraulic fracturing of a coal block by water jets is economical with respect to the consumption of electric power and the unit rate of coal extraction, in addition to being a safe method. 4 references, 4 figures, 2 tables.

Last Glacial to Holocene changes of deep and intermediate water carbonate ion concentrations in the Southern Ocean: constraints from foraminiferal Boron/Calcium ratios

OpenAIRE

Kersten, Franziska

2013-01-01

In this thesis, the first records of intermediate and deep water carbonate ion concentrations in the South Pacific were generated in order to study carbon cycle dynamics throughout the past 30,000 years. Benthic foraminiferal B/Ca, an indicator of past seawater carbonate ion saturation is the main paleoceanographic proxy that was used in this study. Down-core proxy studies carried out within the scope of this thesis were used to address currently unresolved questions about the origin, mechani...

Transport and transformation of surface water masses across the ...

African Journals Online (AJOL)

Transport and transformation of surface water masses across the Mascarene Plateau during the Northeast Monsoon season. ... Mixing occurs in the central gap between intermediate water masses (Red Sea Water [RSW] and Antarctic Intermediate Water [AAIW]) as well as in the upper waters (Subtropical Surface Water ...

Crystal structure of the covalent intermediate of amylosucrase from Neisseria polysaccharea

DEFF Research Database (Denmark)

Jensen, Malene H; Mirza, Osman Asghar; Albenne, Cecile

2004-01-01

The alpha-retaining amylosucrase from the glycoside hydrolase family 13 performs a transfer reaction of a glucosyl moiety from sucrose to an acceptor molecule. Amylosucrase has previously been shown to be able to use alpha-D-glucopyranosyl fluoride as a substrate, which suggested that it could also...... the first covalent intermediate of an alpha-retaining glycoside hydrolase where the glucosyl moiety is identical to the expected biologically relevant entity. Comparison to other enzymes with anticipated glucosylic covalent intermediates suggests that this structure is a representative model...... for such intermediates. Analysis of the active site shows how oligosaccharide binding disrupts the putative nucleophilic water binding site found in the hydrolases of the GH family 13. This reveals important parts of the structural background for the shift in function from hydrolase to transglycosidase seen...

A reconnaissance study of the effect of irrigated agriculture on water quality in the Ogallala Formation, Central High Plains Aquifer

Science.gov (United States)

McMahon, Peter B.

2000-01-01

In 1998, the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program began a regional study of water quality in the High Plains aquifer. The High Plains aquifer underlies an area of about 174,000 square miles in parts of eight States. Because of its large size, the High Plains aquifer has been divided into three regions: the Southern High Plains, Central High Plains, and Northern High Plains. Although an assessment of water quality in each of the three regions is planned, the initial focus will be the Central High Plains aquifer. Anyone who has flown over the Central High Plains in the summer and has seen the large green circles associated with center pivot sprinklers knows that irrigated agriculture is a widespread land use. Pesticides and fertilizers applied on those irrigated fields will not degrade ground-water quality if they remain in or above the root zone. However, if those chemicals move downward through the unsaturated zone to the water table, they may degrade the quality of the ground water. Water is the principal agent for transporting chemicals from land surface to the water table, and in the semiarid Central High Plains, irrigation often represents the most abundant source of water during the growing season. One objective of NAWQA's High Plains Regional Ground-Water study is to evaluate the effect of irrigated agriculture on the quality of recently recharged water in the Ogallala Formation of the Central High Plains aquifer. The Ogallala Formation is the principal geologic unit in the Central High Plains aquifer, and it consists of poorly sorted clay, silt, sand, and gravel that generally is unconsolidated (Gutentag and others, 1984). Approximately 23 percent of the cropland overlying the Ogallala Formation is irrigated (U.S. Department of Agriculture, 1999). The NAWQA Program generally defines recently recharged ground water to be water recharged in the last 50 years. The water table in the Ogallala Formation is separated from

Anode pattern formation in atmospheric pressure air glow discharges with water anode

NARCIS (Netherlands)

Verreycken, T.; Bruggeman, P.J.; Leys, C.

2009-01-01

Pattern formation in the anode layer at a water electrode in atmospheric pressure glow discharges in air is studied. With increasing current a sequence of different anode spot structures occurs from a constricted homogeneous spot in the case of small currents to a pattern consisting of small

Intermediate neutron spectrum problems and the intermediate neutron spectrum experiment

International Nuclear Information System (INIS)

Jaegers, P.J.; Sanchez, R.G.

1996-01-01

Criticality benchmark data for intermediate energy spectrum systems does not exist. These systems are dominated by scattering and fission events induced by neutrons with energies between 1 eV and 1 MeV. Nuclear data uncertainties have been reported for such systems which can not be resolved without benchmark critical experiments. Intermediate energy spectrum systems have been proposed for the geological disposition of surplus fissile materials. Without the proper benchmarking of the nuclear data in the intermediate energy spectrum, adequate criticality safety margins can not be guaranteed. The Zeus critical experiment now under construction will provide this necessary benchmark data

Aquifer composition and the tendency toward scale-deposit formation during reverse osmosis desalination - Examples from saline ground water in New Mexico, USA

Science.gov (United States)

Huff, G.F.

2006-01-01

Desalination is expected to make a substantial contribution to water supply in the United States by 2020. Currently, reverse osmosis is one of the most cost effective and widely used desalination technologies. The tendency to form scale deposits during reverse osmosis is an important factor in determining the suitability of input waters for use in desalination. The tendency toward scale formation of samples of saline ground water from selected geologic units in New Mexico was assessed using simulated evaporation. All saline water samples showed a strong tendency to form CaCO3 scale deposits. Saline ground water samples from the Yeso Formation and the San Andres Limestone showed relatively stronger tendencies to form CaSO4 2H2O scale deposits and relatively weaker tendencies to form SiO2(a) scale deposits than saline ground water samples from the Rio Grande alluvium. Tendencies toward scale formation in saline ground water samples from the Dockum Group were highly variable. The tendencies toward scale formation of saline waters from the Yeso Formation, San Andres Limestone, and Rio Grande alluvium appear to correlate with the mineralogical composition of the geologic units, suggesting that scale-forming tendencies are governed by aquifer composition and water-rock interaction. ?? 2006 Elsevier B.V. All rights reserved.

Investigating the role of biofilms in trihalomethane formation in water distribution systems with a multicomponent model.

Science.gov (United States)

Abokifa, Ahmed A; Yang, Y Jeffrey; Lo, Cynthia S; Biswas, Pratim

2016-11-01

Biofilms are ubiquitous in the pipes of drinking water distribution systems (DWDSs), and recent experimental studies revealed that the chlorination of the microbial carbon associated with the biofilm contributes to the total disinfection by-products (DBPs) formation with distinct mechanisms from those formed from precursors derived from natural organic matter (NOM). A multiple species reactive-transport model was developed to explain the role of biofilms in DBPs formation by accounting for the simultaneous transport and interactions of disinfectants, organic compounds, and biomass. Using parameter values from experimental studies in the literature, the model equations were solved to predict chlorine decay and microbial regrowth dynamics in an actual DWDS, and trihalomethanes (THMs) formation in a pilot-scale distribution system simulator. The model's capability of reproducing the measured concentrations of free chlorine, suspended biomass, and THMs under different hydrodynamic and temperature conditions was demonstrated. The contribution of bacteria-derived precursors to the total THMs production was found to have a significant dependence on the system's hydraulics, seasonal variables, and the quality of the treated drinking water. Under system conditions that promoted fast bacterial re-growth, the transformation of non-microbial into microbial carbon DBP precursors by the biofilms showed a noticeable effect on the kinetics of THMs formation, especially when a high initial chlorine dose was applied. These conditions included elevated water temperature and high concentrations of nutrients in the influent water. The fraction of THMs formed from microbial sources was found to reach a peak of 12% of the total produced THMs under the investigated scenarios. The results demonstrated the importance of integrating bacterial regrowth dynamics in predictive DBPs formation models. Copyright © 2016 Elsevier Ltd. All rights reserved.

Modeling SOA formation from the oxidation of intermediate volatility n-alkanes

Directory of Open Access Journals (Sweden)

J. Lee-Taylor

2012-08-01

Full Text Available The chemical mechanism leading to SOA formation and ageing is expected to be a multigenerational process, i.e. a successive formation of organic compounds with higher oxidation degree and lower vapor pressure. This process is here investigated with the explicit oxidation model GECKO-A (Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere. Gas phase oxidation schemes are generated for the C8–C24 series of n-alkanes. Simulations are conducted to explore the time evolution of organic compounds and the behavior of secondary organic aerosol (SOA formation for various preexisting organic aerosol concentration (COA. As expected, simulation results show that (i SOA yield increases with the carbon chain length of the parent hydrocarbon, (ii SOA yield decreases with decreasing COA, (iii SOA production rates increase with increasing COA and (iv the number of oxidation steps (i.e. generations needed to describe SOA formation and evolution grows when COA decreases. The simulated oxidative trajectories are examined in a two dimensional space defined by the mean carbon oxidation state and the volatility. Most SOA contributors are not oxidized enough to be categorized as highly oxygenated organic aerosols (OOA but reduced enough to be categorized as hydrocarbon like organic aerosols (HOA, suggesting that OOA may underestimate SOA. Results show that the model is unable to produce highly oxygenated aerosols (OOA with large yields. The limitations of the model are discussed.

Isotopic Studies of O-O Bond Formation During Water Oxidation (SISGR)

Energy Technology Data Exchange (ETDEWEB)

Roth, Justine P. [Johns Hopkins Univ., Baltimore, MD (United States)

2015-03-03

Isotopic Studies of O-O Bond Formation During Water Oxidation (SISGR) Research during the project period focused primarily on mechanisms of water oxidation by structurally defined transition metal complexes. Competitive oxygen isotope fractionation of water, mediated by oxidized precursors or reduced catalysts together with ceric, Ce(IV), ammonium nitrate in aqueous media, afforded oxygen-18 kinetic isotope effects (O-18 KIEs). Measurement, calculation, and interpretation of O-18 KIEs, described in the accompanying report has important ramifications for the production of electricity and solar hydrogen (as fuel). The catalysis division of BES has acknowledged that understanding mechanisms of transition metal catalyzed water oxidation has major ramifications, potentially leading to transformation of the global economy and natural environment in years to come. Yet, because of program restructuring and decreased availability of funds, it was recommended that the Solar Photochemistry sub-division of BES would be a more appropriate parent program for support of continued research.

Effect of water unextractable solids on gluten formation and properties: Mechanistic considerations

NARCIS (Netherlands)

Wang, M.; Hamer, R.J.; Vliet, T. van; Gruppen, H.; Marseille, H.; Weegels, P.L.

2003-01-01

A miniaturised set-up for gluten-starch separation was used to systematically study the effect of water unextractable solids (WUS) on the formation and properties of gluten. The results showed that WUS not only have a negative effect on gluten yield, but also affect gluten and glutenin macropolymer

Atmospheric fates of Criegee intermediates in the ozonolysis of isoprene.

Science.gov (United States)

Nguyen, Tran B; Tyndall, Geoffrey S; Crounse, John D; Teng, Alexander P; Bates, Kelvin H; Schwantes, Rebecca H; Coggon, Matthew M; Zhang, Li; Feiner, Philip; Milller, David O; Skog, Kate M; Rivera-Rios, Jean C; Dorris, Matthew; Olson, Kevin F; Koss, Abigail; Wild, Robert J; Brown, Steven S; Goldstein, Allen H; de Gouw, Joost A; Brune, William H; Keutsch, Frank N; Seinfeld, John H; Wennberg, Paul O

2016-04-21

We use a large laboratory, modeling, and field dataset to investigate the isoprene + O3 reaction, with the goal of better understanding the fates of the C1 and C4 Criegee intermediates in the atmosphere. Although ozonolysis can produce several distinct Criegee intermediates, the C1 stabilized Criegee (CH2OO, 61 ± 9%) is the only one observed to react bimolecularly. We suggest that the C4 Criegees have a low stabilization fraction and propose pathways for their decomposition. Both prompt and non-prompt reactions are important in the production of OH (28% ± 5%) and formaldehyde (81% ± 16%). The yields of unimolecular products (OH, formaldehyde, methacrolein (42 ± 6%) and methyl vinyl ketone (18 ± 6%)) are fairly insensitive to water, i.e., changes in yields in response to water vapor (≤4% absolute) are within the error of the analysis. We propose a comprehensive reaction mechanism that can be incorporated into atmospheric models, which reproduces laboratory data over a wide range of relative humidities. The mechanism proposes that CH2OO + H2O (k(H2O)∼ 1 × 10(-15) cm(3) molec(-1) s(-1)) yields 73% hydroxymethyl hydroperoxide (HMHP), 6% formaldehyde + H2O2, and 21% formic acid + H2O; and CH2OO + (H2O)2 (k(H2O)2∼ 1 × 10(-12) cm(3) molec(-1) s(-1)) yields 40% HMHP, 6% formaldehyde + H2O2, and 54% formic acid + H2O. Competitive rate determinations (kSO2/k(H2O)n=1,2∼ 2.2 (±0.3) × 10(4)) and field observations suggest that water vapor is a sink for greater than 98% of CH2OO in a Southeastern US forest, even during pollution episodes ([SO2] ∼ 10 ppb). The importance of the CH2OO + (H2O)n reaction is demonstrated by high HMHP mixing ratios observed over the forest canopy. We find that CH2OO does not substantially affect the lifetime of SO2 or HCOOH in the Southeast US, e.g., CH2OO + SO2 reaction is a minor contribution (production by stabilized Criegees is likely unimportant in regions dominated by the reactivity of ozone with isoprene. In contrast

Gibbs Free Energy of Hydrolytic Water Molecule in Acyl-Enzyme Intermediates of a Serine Protease: A Potential Application for Computer-Aided Discovery of Mechanism-Based Reversible Covalent Inhibitors.

Science.gov (United States)

Masuda, Yosuke; Yamaotsu, Noriyuki; Hirono, Shuichi

2017-01-01

In order to predict the potencies of mechanism-based reversible covalent inhibitors, the relationships between calculated Gibbs free energy of hydrolytic water molecule in acyl-trypsin intermediates and experimentally measured catalytic rate constants (k cat ) were investigated. After obtaining representative solution structures by molecular dynamics (MD) simulations, hydration thermodynamics analyses using WaterMap™ were conducted. Consequently, we found for the first time that when Gibbs free energy of the hydrolytic water molecule was lower, logarithms of k cat were also lower. The hydrolytic water molecule with favorable Gibbs free energy may hydrolyze acylated serine slowly. Gibbs free energy of hydrolytic water molecule might be a useful descriptor for computer-aided discovery of mechanism-based reversible covalent inhibitors of hydrolytic enzymes.

Using Theory to Inform Water Conservation in Business Communities: Formative Research from a Chamber Initiative

Science.gov (United States)

Sarge, Melanie A.; Daggett, Samantha; VanDyke, Matthew S.

2018-01-01

This study was designed to collect formative information for the development of theoretically driven water conservation communication efforts targeting the business sector of water users. Members from a West Texas Chamber of Commerce were recruited for participation in an online survey. Questionnaire responses were collected from 176 commercial…

Mediterranean intermediate circulation estimated from Argo data in 2003–2010

Directory of Open Access Journals (Sweden)

M. Menna

2010-03-01

Full Text Available Data from 38 Argo profiling floats are used to describe the intermediate Mediterranean currents for the period October 2003–January 2010. These floats were programmed to execute 5-day cycles, to drift at a neutral parking depth of 350 m and measure temperature and salinity profiles from either 700 or 2000 m up to the surface. At the end of each cycle the floats remained at the sea surface for about 6 h, enough time to be localised and transmit the data to the Argos satellite system. The Argos positions were used to determine the float surface and intermediate displacements. At the surface, the float motion was approximated by a linear displacement and inertial motion. Intermediate velocities estimates were used to investigate the Mediterranean circulation at 350 m, to compute the pseudo-Eulerian statistics and to study the influence of bathymetry on the intermediate currents. Maximum speeds, as large as 33 cm/s, were found northeast of the Balearic Islands (western basin and in the Ierapetra eddy (eastern basin. Typical speeds in the main along-slope currents (Liguro-Provençal-Catalan, Algerian and Libyo-Egyptian Currents were ~20 cm/s. In the central and western part of Mediterranean basin, the pseudo-Eulerian statistics show typical intermediate circulation pathways which can be related to the motion of Levantine Intermediate Water. In general our results agree with the qualitative intermediate circulation schemes proposed in the literature, except in the southern Ionian where we found westward-flowing intermediate currents. Fluctuating currents appeared to be usually larger than the mean flow. Intermediate currents were found to be essentially parallel to the isobaths over most of the areas characterized by strong bathymetry gradients, in particular, in the vicinity of the continental slopes.

Links Between the Deep Western Boundary Current, Labrador Sea Water Formation and Export, and the Meridional Overturning Circulation

Science.gov (United States)

Myers, Paul G.; Kulan, Nilgun

2010-05-01

Based on an isopyncal analysis of historical data, 3-year overlapping triad fields of objectively analysed temperature and salinity are produced for the Labrador Sea, covering 1949-1999. These fields are then used to spectrally nudge an eddy-permitting ocean general circulation model of the sub-polar gyre, otherwise forced by inter annually varying surface forcing based upon the Coordinated Ocean Reference Experiment (CORE). High frequency output from the reanalysis is used to examine Labrador Sea Water formation and its export. A number of different apprpoaches are used to estimate Labrador Sea Water formation, including an instanteous kinematic approach to calculate the annual rate of water mass subduction at a given density range. Historical transports are computed along sections at 53 and 56N for several different water masses for comparison with recent observations, showing a decline in the stength of the deep western boundary current with time. The variability of the strength of the meridional overturning circulation (MOC) from the reanalysis is also examined in both depth and density space. Linkages between MOC variability and water mass formation variability is considered.

Microstructural and magnetic properties of L10 FePt-C (0 0 1) textured nanocomposite films grown on different intermediate layers

International Nuclear Information System (INIS)

Chen, J S; Chow, G M; Lim, B C; Hu, J F; Ding, Y F; Ju, G

2008-01-01

The FePt : C films with different volume fractions of carbon and different thicknesses were epitaxially grown on a CrRu(2 0 0) underlayer with Pt and MgO intermediate layers. The magnetic properties and microstructure of these FePt : C films were investigated. The FePt : C films grown on the Pt intermediate layer consisted of a continuous layer of FePt, with overlying granular FePt grains, while the FePt : C films grown on the MgO intermediate layer consisted of granular FePt : C layers with overlying granular grains. The formation of the overlying granular FePt grains was attributed to carbon diffusion to the surface which resulted in the second nucleation of FePt. The different interface energies and surface energies of FePt on Pt and MgO intermediate layers caused the formation of an initial continuous FePt layer on the Pt intermediate layer and initial granular FePt layers on the MgO intermediate layer. The coupling between the continuous FePt layer or the granular FePt layer and the overlying granular FePt grains resulted in simultaneous magnetization reversal and thus strong exchange coupling in FePt : C films.

The Effect Of Anisotropy In Formation Permeability On The Efficiency Of Cyclic Water Flooding

Directory of Open Access Journals (Sweden)

Al-Obaidi SH

2017-11-01

Full Text Available In oil industry one of the most worldwide used methods a among the hydrodynamic enhanced oil recovery methods is the water flooding including the cyclic water flooding. The efficiency of cyclic water flooding is affected by a number of geophysical and field technological factors. In this work and based on three-dimensional hydrodynamic simulation it is shown that anisotropy of formation permeability has significant effect on justification of the half-cycle time and the technological effectiveness of the method.

Evaluation of Water Injection Effect on NO(x) Formation for a Staged Gas Turbine Combustor

Science.gov (United States)

Fan, L.; Yang, S. L.; Kundu, K. P.

1996-01-01

NO(x) emission control by water injection on a staged turbine combustor (STC) was modeled using the KIVA-2 code with modification. Water is injected into the rich-burn combustion zone of the combustor by a single nozzle. Parametric study for different water injection patterns was performed. Results show NO(x) emission will decrease after water being injected. Water nozzle location also has significant effect for NO formation and fuel ignition. The chemical kinetic model is also sensitive to the excess water. Through this study, a better understanding of the physics and chemical kinetics is obtained, this will enhance the STC design process.

The occurrence of perchlorate during drinking water electrolysis using BDD anodes

International Nuclear Information System (INIS)

Bergmann, M.E. Henry; Rollin, Johanna; Iourtchouk, Tatiana

2009-01-01

Electrochemical studies were carried out to estimate the risks of perchlorate formation in drinking water disinfected by direct electrolysis. Boron Doped Diamond (BDD) anodes were used in laboratory and commercially available cells at 20 deg. C. The current density was changed between 50 and 500 A m -2 . For comparison, other anode materials such as platinum and mixed oxide were also tested. It was found that BDD anodes have a thousandfold higher perchlorate formation potential compared with the other electrode materials that were tested. In long-term discontinuous experiments all the chloride finally reacted to form perchlorate. The same result was obtained when probable oxychlorine intermediates (OCl - , ClO 2 - , ClO 3 - ) were electrolysed in synthetic waters in the ppm range of concentrations. The tendency to form perchlorate was confirmed when the flow rate of drinking water was varied between 100 and 300 L h -1 and the temperature increased to 30 deg. C. In a continuous flow mode of operation a higher chloride concentration in the water resulted in a lower perchlorate formation. This can be explained by reaction competition of species near and on the anode surface for experiments both with synthetic and local drinking waters. It is concluded that the use of electrodes producing highly reactive species must be more carefully controlled in hygienically and environmentally oriented applications

Nitrenes, carbenes, diradicals, and ylides. Interconversions of reactive intermediates.

Science.gov (United States)

Wentrup, Curt

2011-06-21

Rearrangements of aromatic and heteroaromatic nitrenes and carbenes can be initiated with either heat or light. The thermal reaction is typically induced by flash vacuum thermolysis, with isolation of the products at low temperatures. Photochemical experiments are conducted either under matrix isolation conditions or in solution at ambient temperature. These rearrangements are usually initiated by ring expansion of the nitrene or carbene to a seven-membered ring ketenimine, carbodiimide, or allene (that is, a cycloheptatetraene or an azacycloheptatetraene when a nitrogen is involved). Over the last few years, we have found that two types of ring opening take place as well. Type I is an ylidic ring opening that yields nitrile ylides or diazo compounds as transient intermediates. Type II ring opening produces either dienylnitrenes (for example, from 2-pyridylnitrenes) or 1,7-(1,5)-diradicals (such as those formed from 2-quinoxalinylnitrenes), depending on which of these species is better stabilized by resonance. In this Account, we describe our achievements in elucidating the nature of the ring-opened species and unraveling the connections between the various reactive intermediates. Both of these ring-opening reactions are found, at least in some cases, to dominate the subsequent chemistry. Examples include the formation of ring-opened ketenimines and carbodiimides, as well as the ring contraction reactions that form five-membered ring nitriles (such as 2- and 3-cyanopyrroles from pyridylnitrenes, N-cyanoimidazoles from 2-pyrazinyl and 4-pyrimidinylnitrenes, N-cyanopyrazoles from 2-pyrimidinylnitrenes and 3-pyridazinylnitrenes, and so forth). The mechanisms of formation of the open-chain and ring-contraction products were unknown at the onset of this study. In the course of our investigation, several reactions with three or more consecutive reactive intermediates have been unraveled, such as nitrene, seven-membered cyclic carbodiimide, and open-chain nitrile ylide

Methane recovery from coal mine gas using hydrate formation in water-in-oil emulsions

International Nuclear Information System (INIS)

Zhong, Dong-Liang; Ding, Kun; Lu, Yi-Yu; Yan, Jin; Zhao, Wei-Long

2016-01-01

Highlights: • A water-in-oil emulsion was developed for CH_4 separation from coal mine methane gas. • Stable W/O emulsions were obtained with water cut in the range of (10–70%). • Gas hydrates nucleated faster with the reduction of water–oil volume ratio. • Gas uptake increased with the decrease of water–oil volume ratio. • CH_4 recovery was greatly enhanced by hydrate formation in W/O emulsions. - Abstract: In this work, a water-in-oil (W/O) emulsion was developed using liquid water, mineral oil, Sorbitan monooleate (Span 80), and cyclopentane. It was employed to enhance gas hydrate formation for CH_4 separation from a simulated coal mine methane (CMM) gas (30 mol% CH_4, 60 mol% N_2, and 10 mol% O_2). The stability test at atmospheric pressure and at a high pressure of 3.5 MPa showed that stable W/O emulsions were obtained when the water–oil volume ratio (WOR) was below 80%. The emulsified droplets size was measured with WOR ranging from 10% to 70%. Then kinetic experiments of CH_4 separation by hydrate formation in W/O emulsions were carried out at 273.6 K and (3.5–5.0) MPa in batch operation. The results indicated that water–oil volume ratio is a key factor that affects the kinetics of gas hydrate formation from the CMM gas mixture. Hydrate nucleation was observed to occur faster while WOR was decreased, and gas uptake increased significantly with the decrease of WOR. CH_4 concentration in the recovered gas mixture was increased to 52 mol% as compared to 30 mol% in the original gas mixture through one-stage hydrate formation in the W/O emulsions. It was found that the experimental conditions of 273.6 K, 3.5 MPa and WOR = 30% were favorable for CH_4 recovery from the CMM gas. The CH_4 recovery obtained under these conditions was 43%. It was higher than those obtained at WOR = 10% and 70%, and was greatly increased as compared with those obtained in the same reactor with the presence of TBAB (26%) and CP (33%).

XAFS studies of monodisperse Au nanoclusters formation in the etching process

International Nuclear Information System (INIS)

Yang, Lina; Huang, Ting; Liu, Wei; Bao, Jie; Huang, Yuanyuan; Cao, Yuanjie; Yao, Tao; Sun, Zhihu; Wei, Shiqiang

2016-01-01

Understanding the formation mechanism of gold nanoclusters is essential to the development of their synthetic chemistry. Here, by using x-ray absorption fine-structure (XAFS) spectroscopy, UV-Vis and MS spectra, the formation process of monodisperse Au 13 nanoclusters is investigated. We find that a critical step involving the formation of smaller Au 8 -Au 11 metastable intermediate clusters induced by the HCl + HSR etching of the polydisperse Au n precursor clusters occurs firstly. Then these intermediate species undergo a size-growth to Au 13 cores, followed by a slow structure rearrangement to reach the final stable structure. This work enriches the understanding of cluster formation chemistry and may guide the way towards the design and the controllable synthesis of nanoclusters. (paper)

Protein phosphatase dependent circadian regulation of intermediate-term associative memory

OpenAIRE

Michel, Maximilian; Gardner, Jacob S.; Green, Charity L.; Organ, Chelsea L.; Lyons, Lisa C.

2013-01-01

The endogenous circadian clock is a principal factor modulating memory across species. Determining the processes through which the circadian clock modulates memory formation is a key issue in understanding and identifying mechanisms to improve memory. We used the marine mollusk Aplysia californica to investigate circadian modulation of intermediate-term memory (ITM) and the mechanisms through which the circadian clock phase specifically suppresses memory using the operant learning paradigm, l...

Violent storms within the sea: Dense water formation episodes in the Mediterranean.

Science.gov (United States)

Salat, J.

2009-09-01

The Mediterranean is a semi enclosed basin which receives surface water from the Atlantic Ocean. Most of this water is returned into the Ocean with higher density, spreading at more than 1000 m depth (the rest is transported by the atmosphere and the rivers to the Ocean surface). In terms of water budget, the Mediterranean is considered an evaporation basin, but the loss of water is neither the only process that increases the water density nor it is a steady or uniform process. The factors affecting the water density, temperature and salinity, are driven by mass and heat exchanges with the atmosphere. Those exchanges may be by direct contact or mediated by the land. Therefore, changes in water density depend on the water circulation and local weather conditions, both with seasonal and geographical constraints. As the compressibility of water is very low, stratification is expected and horizontal motion is the predominant in the sea interior. Among the few processes that may introduce a vertical component in the water motion are surface heat loss or evaporation that increase the surface water density triggering convective cells. Such processes will be enhanced by surface cooling or by dry continental winds, and counterbalanced by rain, river runoff, solar heating and condensation. Therefore dense water formation are more likely to occur when sea surface temperature is higher than the surface air temperature. There are several scales of convective motions in the ocean, starting from the formation of the surface mixed layer during summer, by night cooling, breezes, and occasional wind storms. During autumn and winter, the vertical scale of the mixing is increasing by steps, through wind storms and progressive cooling, to easily reach the bottom over the continental shelves, typically not deeper than 150 m. However, as the Gibraltar sill is relatively shallow (~350 m) in relation to the average Mediterranean basin (2000-3000 m), the stratification of the deeper layers

pH-induced inversion of water-in-oil emulsions to oil-in-water high internal phase emulsions (HIPEs) using core cross-linked star (CCS) polymer as interfacial stabilizer.

Science.gov (United States)

Chen, Qijing; Deng, Xiaoyong; An, Zesheng

2014-06-01

A pH-responsive core cross-linked star (CCS) polymer containing poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) arms was used as an interfacial stabilizer for emulsions containing toluene (80 v%) and water (20 v%). In the pH range of 12.1-9.3, ordinary water-in-oil emulsions were formed. Intermediate multiple emulsions of oil-in-water-in-oil and water-in-oil-in-water were formed at pH 8.6 and 7.5, respectively. Further lowering the pH resulted in the formation of gelled high internal phase emulsions of oil-in-water type in the pH range of 6.4-0.6. The emulsion behavior was correlated with interfacial tension, conductivity and configuration of the CCS polymer at different pH. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The natural chlorine cycle - Formation of the carcinogenic and greenhouse gas compound chloroform in drinking water reservoirs.

Science.gov (United States)

Forczek, Sándor T; Pavlík, Milan; Holík, Josef; Rederer, Luděk; Ferenčík, Martin

2016-08-01

Chlorine cycle in natural ecosystems involves formation of low and high molecular weight organic compounds of living organisms, soil organic matter and atmospherically deposited chloride. Chloroform (CHCl3) and adsorbable organohalogens (AOX) are part of the chlorine cycle. We attempted to characterize the dynamical changes in the levels of total organic carbon (TOC), AOX, chlorine and CHCl3 in a drinking water reservoir and in its tributaries, mainly at its spring, and attempt to relate the presence of AOX and CHCl3 with meteorological, chemical or biological factors. Water temperature and pH influence the formation and accumulation of CHCl3 and affect the conditions for biological processes, which are demonstrated by the correlation between CHCl3 and ΣAOX/Cl(-) ratio, and also by CHCl3/ΣAOX, CHCl3/AOXLMW, CHCl3/ΣTOC, CHCl3/TOCLMW and CHCl3/Cl(-) ratios in different microecosystems (e.g. old spruce forest, stagnant acidic water, humid and warm conditions with high biological activity). These processes start with the biotransformation of AOX from TOC, continue via degradation of AOX to smaller molecules and further chlorination, and finish with the formation of small chlorinated molecules, and their subsequent volatilization and mineralization. The determined concentrations of chloroform result from a dynamic equilibrium between its formation and degradation in the water; in the Hamry water reservoir, this results in a total amount of 0.1-0.7 kg chloroform and 5.2-15.4 t chloride. The formation of chloroform is affected by Cl(-) concentration, by concentrations and ratios of biogenic substrates (TOC and AOX), and by the ratios of the substrates and the product (feedback control by chloroform itself). Copyright © 2016 Elsevier Ltd. All rights reserved.

The Metallicity Evolution of Low Mass Galaxies: New Contraints at Intermediate Redshift

Science.gov (United States)

Henry, Alaina; Martin, Crystal L.; Finlator, Kristian; Dressler, Alan

2013-01-01

We present abundance measurements from 26 emission-line-selected galaxies at z approx. 0.6-0.7. By reaching stellar masses as low as 10(exp 8) M stellar mass, these observations provide the first measurement of the intermediate-redshift mass-metallicity (MZ) relation below 10(exp 9)M stellar mass. For the portion of our sample above M is greater than 10(exp 9)M (8/26 galaxies), we find good agreement with previous measurements of the intermediate-redshift MZ relation. Compared to the local relation, we measure an evolution that corresponds to a 0.12 dex decrease in oxygen abundances at intermediate redshifts. This result confirms the trend that metallicity evolution becomes more significant toward lower stellar masses, in keeping with a downsizing scenario where low-mass galaxies evolve onto the local MZ relation at later cosmic times. We show that these galaxies follow the local fundamental metallicity relation, where objects with higher specific (mass-normalized) star formation rates (SFRs) have lower metallicities. Furthermore, we show that the galaxies in our sample lie on an extrapolation of the SFR-M* relation (the star-forming main sequence). Leveraging the MZ relation and star-forming main sequence (and combining our data with higher-mass measurements from the literature), we test models that assume an equilibrium between mass inflow, outflow, and star formation.We find that outflows are required to describe the data. By comparing different outflow prescriptions, we show that momentum, driven winds can describe the MZ relation; however, this model underpredicts the amount of star formation in low-mass galaxies. This disagreement may indicate that preventive feedback from gas heating has been overestimated, or it may signify a more fundamental deviation from the equilibrium assumption.

Accurate Treatment of Collisions and Water-Delivery in Models of Terrestrial Planet Formation

Science.gov (United States)

Haghighipour, Nader; Maindl, Thomas; Schaefer, Christoph

2017-10-01

It is widely accepted that collisions among solid bodies, ignited by their interactions with planetary embryos is the key process in the formation of terrestrial planets and transport of volatiles and chemical compounds to their accretion zones. Unfortunately, due to computational complexities, these collisions are often treated in a rudimentary way. Impacts are considered to be perfectly inelastic and volatiles are considered to be fully transferred from one object to the other. This perfect-merging assumption has profound effects on the mass and composition of final planetary bodies as it grossly overestimates the masses of these objects and the amounts of volatiles and chemical elements transferred to them. It also entirely neglects collisional-loss of volatiles (e.g., water) and draws an unrealistic connection between these properties and the chemical structure of the protoplanetary disk (i.e., the location of their original carriers). We have developed a new and comprehensive methodology to simulate growth of embryos to planetary bodies where we use a combination of SPH and N-body codes to accurately model collisions as well as the transport/transfer of chemical compounds. Our methodology accounts for the loss of volatiles (e.g., ice sublimation) during the orbital evolution of their careers and accurately tracks their transfer from one body to another. Results of our simulations show that traditional N-body modeling of terrestrial planet formation overestimates the amount of the mass and water contents of the final planets by over 60% implying that not only the amount of water they suggest is far from being realistic, small planets such as Mars can also form in these simulations when collisions are treated properly. We will present details of our methodology and discuss its implications for terrestrial planet formation and water delivery to Earth.

Disinfection byproduct formation during biofiltration cycle: Implications for drinking water production.

Science.gov (United States)

Delatolla, R; Séguin, C; Springthorpe, S; Gorman, E; Campbell, A; Douglas, I

2015-10-01

The goal of this study was to investigate the potential of biofiltration to reduce the formation potential of disinfection byproducts (DBPs). Particularly, the work investigates the effect of the duration of the filter cycle on the formation potential of total trihalomethanes (TTHM) and five species of haloacetic acids (HAA5), dissolved oxygen (DO), organic carbon, nitrogen and total phosphorous concentrations along with biofilm coverage of the filter media and biomass viability of the attached cells. The study was conducted on a full-scale biologically active filter, with anthracite and sand media, at the Britannia water treatment plant (WTP), located in Ottawa, Ontario, Canada. The formation potential of both TTHMs and HAA5s decreased due to biofiltration. However the lowest formation potentials for both groups of DBPs and or their precursors were observed immediately following a backwash event. Hence, the highest percent removal of DBPs was observed during the early stages of the biofiltration cycle, which suggests that a higher frequency of backwashing will reduce the formation of DBPs. Variable pressure scanning electron microscopy (VPSEM) analysis shows that biofilm coverage of anthracite and sand media increases as the filtration cycle progressed, while biomass viability analysis demonstrates that the percentage of cells attached to the anthracite and sand media also increases as the filtration cycle progresses. These results suggest that the development and growth of biofilm on the filters increases the DPB formation potential. Copyright © 2015 Elsevier Ltd. All rights reserved.

Critical Intermediate Structure That Directs the Crystalline Texture and Surface Morphology of Organo-Lead Trihalide Perovskite.

Science.gov (United States)

Chia, Hao-Chung; Sheu, Hwo-Shuenn; Hsiao, Yu-Yun; Li, Shao-Sian; Lan, Yi-Kang; Lin, Chung-Yao; Chang, Je-Wei; Kuo, Yen-Chien; Chen, Chia-Hao; Weng, Shih-Chang; Su, Chun-Jen; Su, An-Chung; Chen, Chun-Wei; Jeng, U-Ser

2017-10-25

We have identified an often observed yet unresolved intermediate structure in a popular processing with dimethylformamide solutions of lead chloride and methylammonium iodide for perovskite solar cells. With subsecond time-resolved grazing-incidence X-ray scattering and X-ray photoemission spectroscopy, supplemental with ab initio calculation, the resolved intermediate structure (CH 3 NH 3 ) 2 PbI 2 Cl 2 ·CH 3 NH 3 I features two-dimensional (2D) perovskite bilayers of zigzagged lead-halide octahedra and sandwiched CH 3 NH 3 I layers. Such intermediate structure reveals a hidden correlation between the intermediate phase and the composition of the processing solution. Most importantly, the 2D perovskite lattice of the intermediate phase is largely crystallographically aligned with the [110] planes of the three-dimensional perovskite cubic phase; consequently, with sublimation of Cl ions from the organo-lead octahedral terminal corners in prolonged annealing, the zigzagged octahedral layers of the intermediate phase can merge with the intercalated methylammonium iodide layers for templated growth of perovskite crystals. Regulated by annealing temperature and the activation energies of the intermediate and perovskite, deduced from analysis of temperature-dependent structural kinetics, the intermediate phase is found to selectively mature first and then melt along the layering direction for epitaxial conversion into perovskite crystals. The unveiled epitaxial conversion under growth kinetics controls might be general for solution-processed and intermediate-templated perovskite formation.

Criegee Intermediates: What Direct Production and Detection Can Teach Us About Reactions of Carbonyl Oxides

Science.gov (United States)

Taatjes, Craig A.

2017-05-01

The carbonyl oxide intermediates in the ozonolysis of alkenes, often known as Criegee intermediates, are potentially important reactants in Earth's atmosphere. For decades, careful analysis of ozonolysis systems was employed to derive an understanding of the formation and reactions of these species. Recently it has proved possible to synthesize at least some of these intermediates separately from ozonolysis, and hence to measure their reaction kinetics directly. Direct measurements have allowed new or more detailed understanding of each type of gas-phase reaction that carbonyl oxides undergo, often acting as a complement to highly detailed ozonolysis experiments. Moreover, the use of direct characterization methods to validate increasingly accurate theoretical investigations can enhance their impact well beyond the set of specific reactions that have been measured. Reactions that initiate particles or fuel their growth could be a new frontier for direct measurements of Criegee intermediate chemistry.

Introductory Overview of Intermediate-luminosity X-ray Objects

Science.gov (United States)

Colbert, E. J. M.

2001-05-01

Intermediate-luminosity X-ray Objects (IXOs) are defined as compact objects having X-ray luminosities between those of X-ray binaries and low-luminosity AGNs (i.e., 1039.0 erg s-1 < ~ LX [IXOs] < ~ 1041.0 erg s-1). It is not currently known if these objects are intermediate-mass (M ~ 102-104 Msun) black holes accreting near the Eddington limit, near-solar-mass black holes in a super-Eddington state, or are, in some cases, just supermassive black holes accreting at very low rates. However, the first idea has been popularized by recent press coverage. IXOs are quite common (present in about half of spiral galaxies) and are typically found displaced from the optical nucleus, reducing the likelihood that they are low-luminosity AGN. Nearly all of our knowledge of these objects comes from X-ray observations, as observations of optical, NIR and radio counterparts are not widely known. In this session, we will address (1) the phenomenology of the objects, (2) possible geometry and accretion mechanisms for these objects (i.e., are they more similar to black hole X-ray binaries or AGNs), (3) the central black hole masses, and (4) the formation mechanism for these black holes, if they are of intermediate mass. In this talk, I will focus primarily on giving background information of these fascinating objects.

Apparatus for use in predicting hydrocarbon potential of an earth formation underlying a body of water

International Nuclear Information System (INIS)

Demaison, G.J.; Kaplan, I.R.

1984-01-01

In a relatively quick, convenient and highly accurate technique for the determination of a carbonaceous gas, normally methane, contained in water samples collected at depth from a body of water overlying an earth formation to predict the hydrocarbon-containing potential of the earth formation, carbonaceous gaseous constituents liberated from the water are carried via an air stream to flow into and through an isotope trapping network where collection in microlitre amounts occurs. The isotope capture apparatus comprises a box-like structure formed from a series of panel members, front panel member intersecting the bottom panel member near the centre of the latter and carrying interconnected gas trapping and stripping sections, the structure also comprising a detachable lid connectable by means, for protection of sections. (author)

Positron scattering by atomic hydrogen including positronium formation

International Nuclear Information System (INIS)

Higgins, K.; Burke, P.G.

1993-01-01

Positron scattering by atomic hydrogen including positronium formation has been formulated using the R-matrix method and a general computer code written. Partial wave elastic and ground state positronium formation cross sections have been calculated for L ≤ 6 using a six-state approximation which includes the ground state and the 2s and 2p pseudostates of both hydrogen and positronium. The elastic scattering results obtained are in good agreement with those derived from a highly accurate calculation based upon the intermediate energy R-matrix approach. As in a previous coupled-channel static calculation, resonance effects are observed at intermediate energies in the S-wave positronium formation cross section. However, in the present results, the dominant resonance arises in the P-wave cross sections at an energy of 2.73 Ryd and with a width of 0.19 Ryd. (author)

La0.6Sr0.4Co0.2Fe0.8O3-δ nanofiber cathode for intermediate-temperature solid oxide fuel cells by water-based sol-gel electrospinning: Synthesis and electrochemical behaviour

DEFF Research Database (Denmark)

Enrico, Anna; Zhang, Wenjing (Angela); Traulsen, Marie Lund

2018-01-01

Water-based sol-gel electrospinning is employed to manufacture perovskite oxide La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) nanofiber cathodes for intermediate-temperature solid oxide fuel cells. LSCF fibrous scaffolds are synthesized through electrospinning of a sol-gel solution employing water as the only...

Multivariate Analysis Of Ground Water Characteristics Of Geological Formations Of Enugu State Of Nigeria

Directory of Open Access Journals (Sweden)

Orakwe

2015-08-01

Full Text Available Abstract The chemometric data mining techniques using principal factor analysis PFA and hierarchical cluster analysis CA was employed to evaluate and to examine the borehole characteristics of geological formations of Enugu State of Nigeria to determine the latent structure of the borehole characteristics and to classify 9 borehole parameters from 49 locations into borehole groups of similar characteristics. PFA extracted three factors which accounted for a large proportion of the variation in the data 77.305 of the variance. Out of nine parameters examined the first PFA had the highest number of variables loading on a single factor where four borehole parameters borehole depth borehole casing static water level and dynamic water level loaded on it with positive coefficient as the most significant parameters responsible for variation in borehole characteristics in the study. The CA employed in this study to identified three clusters. The first cluster delineated stations that characterise Awgu sandstone geological formation while the second cluster delineated Agbani sandstone geological formation. The third cluster delineated Ajali sandstone formation. The CA grouping of the borehole parameters showed similar trend with PFA hence validating the efficiency of chemometric data mining techniques in grouping of variations in the borehole characteristics in the geological zone of the study area.

Secondary formation of disinfection by-products by UV treatment of swimming pool water

DEFF Research Database (Denmark)

Spiliotopoulou, Aikaterini; Hansen, Kamilla Marie Speht; Andersen, Henrik Rasmus

2015-01-01

Formation of disinfection by-products (DBPs) during experimental UV treatment of pool water has previously been reported with little concurrence between laboratory studies, field studies and research groups. In the current study, changes in concentration of seven out of eleven investigated volatile...

Paleoecological insights from fossil freshwater mollusks of the Kanapoi Formation (Omo-Turkana Basin, Kenya).

Science.gov (United States)

Van Bocxlaer, Bert

2017-09-13

The Early Pliocene Kanapoi Formation of the Omo-Turkana Basin consists of two fluvial/deltaic sedimentary sequences with an intermediate lacustrine sequence that was deposited in Paleolake Lonyumun, the earliest large lake in the basin. Overall, the geology and vertebrate paleontology of the Kanapoi Formation are well studied, but its freshwater mollusks, despite being a major component of the benthic ecosystem, have not been subjected to in-depth study. Here I present the first treatment of these mollusks, which have been retrieved mainly from the lacustrine but also from the upper fluvial sediments, with a focus on paleoecological implications. Overall, the freshwater mollusk fauna is reasonably diverse and contains the gastropods Bellamya (Viviparidae), Melanoides (Thiaridae), Cleopatra (Paludomidae) and Gabbiella (Bithyniidae), as well as the unionoid bivalves Coelatura, Pseudobovaria (Unionidae), Aspatharia, Iridina (Iridinidae) and Etheria (Etheriidae). Material is typically recrystallized and lithified and its taphonomy suggests deposition in a system with intermediate energy, such as a beach, with post-depositional deformation and abrasion. The mollusk assemblage is indicative of perennial, fresh and well-oxygenated waters in the Kanapoi region. It suggests that Paleolake Lonyumun had largely open shores with limited vegetation and that swampy or ephemeral backwaters were rare. Overall, these findings support earlier paleoecological interpretations based on the fish assemblage of Paleolake Lonyumun at Kanapoi. Moreover, mollusk assemblages from this lake are very similar across the Omo-Turkana Basin (Nachukui, Usno, Mursi and Koobi Fora Formations) suggesting that the lacustrine paleoecological conditions found in the Kanapoi Formation existed throughout the basin. Copyright © 2017 Elsevier Ltd. All rights reserved.

Formation of iodo-trihalomethanes, iodo-acetic acids, and iodo-acetamides during chloramination of iodide-containing waters: Factors influencing formation and reaction pathways

Energy Technology Data Exchange (ETDEWEB)

Liu, Shaogang [Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing, 100085 (China); Guangxi Colleges and Universities Key Laboratory of Food Safety and Pharmaceutical Analytical Chemistry, Guangxi Key Laboratory of Chemistry and Engineering of Forest Products, School of Chemistry and Chemical Engineering, Guangxi University for Nationalities, Nanning, 530006, Guangxi (China); Li, Zhenlin [Guangxi Colleges and Universities Key Laboratory of Food Safety and Pharmaceutical Analytical Chemistry, Guangxi Key Laboratory of Chemistry and Engineering of Forest Products, School of Chemistry and Chemical Engineering, Guangxi University for Nationalities, Nanning, 530006, Guangxi (China); Dong, Huiyu [Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing, 100085 (China); Goodman, Bernard A. [College of Physical Science and Engineering, State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning, 520004, Guangxi (China); Qiang, Zhimin, E-mail: qiangz@rcees.ac.cn [Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing, 100085 (China)

2017-01-05

This study investigated systematically the factors influencing the formation of iodinated disinfection by-products (I-DBPs) during chloramination of I{sup −}-containing waters, including reaction time, NH{sub 2}Cl dose, I{sup −} concentration, pH, natural organic matter (NOM) concentration, Br{sup −}/I{sup −} molar ratio, and water matrix. Among the I-DBPs detected, iodoform (CHI{sub 3}), iodoacetic acid (IAA), diiodoacetic acid (DIAA), triiodoacetic acid (TIAA), and diiodoacetamide (DIAcAm) were the major species produced from reactions between reactive iodine species (HOI/I{sub 2}) and NOM. A kinetic model involving the reactions of NH{sub 2}Cl auto-decomposition, iodine species transformation and NOM consumption was developed, which could well describe NH{sub 2}Cl decay and HOI/I{sub 2} evolution. Higher concentrations of CHI{sub 3}, IAA, DIAA, TIAA, and DIAcAm were observed in chloramination than in chlorination, whereas IO{sub 3}{sup −} was only formed significantly in chlorination. Maximum formation of I-DBPs occurred at pH 8.0, but acidic conditions favored the formation of iodinated haloacetic acids and DIAcAm. Increasing Br{sup −}/I{sup −} molar ratio from 1 to 10 did not increase the total amount of I-DBPs, but produced more bromine-substituting species. In addition, chloramination of 18 model compounds indicated that low-SUVA{sub 254} (specific ultraviolet absorbance at 254 nm) NOM generally favored the formation of I-DBPs compared to high-SUVA{sub 254} NOM. Finally, potential pathways for I-DBPs formation from chloramination of NOM were proposed.

The South-to-North Water Diversion Project: effect of the water diversion pattern on transmission of Oncomelania hupensis, the intermediate host of Schistosoma japonicum in China.

Science.gov (United States)

Liang, You-Sheng; Wang, Wei; Li, Hong-Jun; Shen, Xue-Hui; Xu, Yong-Liang; Dai, Jian-Rong

2012-03-20

The South-to-North Water Diversion Project (SNWDP) is the largest national water conservancy project in China. However, the Eastern Route Project (ERP) of SNWDP will refer to the habitats of Oncomelania hupensis, the intermediate host of Schistosoma japonicum. The present study was aimed at investigating the effects of some factors relating to the water diversion pattern on the spread north of O. hupensis and transmission of S. japonicum. Marked snails were attached to the floating debris, and then placed on the water surface, the passage of snails through water pumps was observed. Some marked living adult snails were placed under water in the 5 spots, 15, 30, 60, 90 and 120 days later, their survival and transfer under water were investigated. 2, 4, 8, 16, 32, 64 and 128 juvenile snails, with a male: female ratio of about 1, were caged, 1 year later, their reproductions were calculated. The snails attached on the floating debris at 100-, 50- and 20-cm-distance from the inlet pipe of the big pump (with a diameter of 80 cm), could be absorbed into the pumps, with passing rates of 2.45%, 3.93% and 43.46%, respectively, compared with 72.07% and 91.00% for the snails at 20 cm and 10 cm-distance from the inlet pipe of the small pump (with a diameter of 20 cm). A total of 36,600 marked living snails were put into 5 ponds and ditches, with the water depths of 1-1.6 m, 15-120 days later, no marked ones were found along the ponds and ditches or in the straw packages. The juvenile snails did not reproduce until their density reached up to 8 snails (ratio of male: female of 1)/0.16 m2. During the construction of ERP of SNWDP, the risk of northward spread of schistosomiasis japonica will be decreased or eliminated as long as long-term reliable interventions for snail control are implemented.

Stopped Flow Kinetics of MnII Catalysed Periodate Oxidation of 2, 3- dimethylaniline - Evaluation of Stability Constant of the Ternary Intermediate Complex

Directory of Open Access Journals (Sweden)

Rajneesh Dutt Kaushik

2015-03-01

Full Text Available The formation of ternary intermediate unstable complex during the oxidation of aromatic amines by periodate ion catalysed by MnII has been proposed in case of some anilines. This paper is the first report on stopped-flow kinetic study and evaluation of stability constant of ternary complex forming in the MnII - catalysed periodate oxidation of 2, 3-dimethylaniline (D in acetone-water medium. Stop-flow spectrophotometric method was used to study the ternary complex formation and to determine its stability constant. The stop-flow trace shows the reaction to occur in two steps. The first step, which is presumably the formation of ternary complex, is relatively fast while the second stage is relatively quite slow. The stability constant evaluated for D - MnII - IO4- ternary complex by determining  equilibrium absorbance is (2.2 ± 1.0 × 105. Kinetics of ternary complex formation was defined by the rate law(A  under pseudo first order conditions. ln{[C2]eq / ( [C2]eq -[C2]} = kobs . t (A where, kobs is the pseudo first order rate constant, [C2] is concentration of ternary complex at given time t, and [C2]eq is the equilibrium concentration of ternary complex. © 2015 BCREC UNDIP. All rights reservedReceived: 3rd October 2014; Revised: 4th December 2014; Accepted: 15th December 2014How to Cite: Kaushik, R.D., Agarwal, R., Tyagi, P., Singh, O., Singh, J. (2015. Stopped Flow Kinetics of MnII Catalysed Periodate Oxidation of 2,3-dimethylaniline - Evaluation of Stability Constant of the Ternary Intermediate Complex. Bulletin of Chemical Reaction Engineering & Catalysis, 10 (1: 78-87. (doi:10.9767/bcrec.10.1.7621.78-87Permalink/DOI: http://dx.doi.org/10.9767/bcrec.10.1.7621.78-87

Subsurface water and clay mineral formation during the early history of Mars.

Science.gov (United States)

Ehlmann, Bethany L; Mustard, John F; Murchie, Scott L; Bibring, Jean-Pierre; Meunier, Alain; Fraeman, Abigail A; Langevin, Yves

2011-11-02

Clay minerals, recently discovered to be widespread in Mars's Noachian terrains, indicate long-duration interaction between water and rock over 3.7 billion years ago. Analysis of how they formed should indicate what environmental conditions prevailed on early Mars. If clays formed near the surface by weathering, as is common on Earth, their presence would indicate past surface conditions warmer and wetter than at present. However, available data instead indicate substantial Martian clay formation by hydrothermal groundwater circulation and a Noachian rock record dominated by evidence of subsurface waters. Cold, arid conditions with only transient surface water may have characterized Mars's surface for over 4 billion years, since the early-Noachian period, and the longest-duration aqueous, potentially habitable environments may have been in the subsurface.

Photocatalytic degradation of paracetamol: intermediates and total reaction mechanism.

Science.gov (United States)

Moctezuma, Edgar; Leyva, Elisa; Aguilar, Claudia A; Luna, Raúl A; Montalvo, Carlos

2012-12-01

The advanced oxidation of paracetamol (PAM) promoted by TiO(2)/UV system in aqueous medium was investigated. Monitoring this reaction by HPLC and TOC, it was demonstrated that while oxidation of paracetamol is quite efficient under these conditions, its mineralization is not complete. HPLC indicated the formation of hydroquinone, benzoquinone, p-aminophenol and p-nitrophenol in the reaction mixtures. Further evidence of p-nitrophenol formation was obtained following the reaction by UV-vis spectroscopy. Continuous monitoring by IR spectroscopy demonstrated the breaking of the aromatic amide present in PAM and subsequent formation of several aromatic intermediate compounds such as p-aminophenol and p-nitrophenol. These aromatic compounds were eventually converted into trans-unsaturated carboxylic acids. Based on these experimental results, an alternative deacylation mechanism for the photocatalytic oxidation of paracetamol is proposed. Our studies also demonstrated IR spectroscopy to be a useful technique to investigate oxidative mechanisms of pharmaceutical compounds. Copyright © 2012 Elsevier B.V. All rights reserved.

The Dependence of Chlorine Decay and DBP Formation Kinetics On Pipe Flow Properties in Drinking Water Distribution

Science.gov (United States)

Simultaneous chlorine decay and disinfection byproduct (DBP) formation has long been discussed because of its regulatory and operational significance. This study further examines the water quality changes under hydrodynamic settings during drinking water distribution. Comparative...

Influence of drinking water treatments on chlorine dioxide consumption and chlorite/chlorate formation.

Science.gov (United States)

Sorlini, Sabrina; Gialdini, Francesca; Biasibetti, Michela; Collivignarelli, Carlo

2014-05-01

Disinfection is the last treatment stage of a Drinking Water Treatment Plant (DWTP) and is carried out to maintain a residual concentration of disinfectant in the water distribution system. Chlorine dioxide (ClO2) is a widely used chemical employed for this purpose. The aim of this work was to evaluate the influence of several treatments on chlorine dioxide consumption and on chlorite and chlorate formation in the final oxidation/disinfection stage. A number of tests was performed at laboratory scale employing water samples collected from the DWTP of Cremona (Italy). The following processes were studied: oxidation with potassium permanganate, chlorine dioxide and sodium hypochlorite, coagulation/flocculation with ferric chloride and aluminum sulfate, filtration and adsorption onto activated carbon. The results showed that the chlorine dioxide demand is high if sodium hypochlorite or potassium permanganate are employed in pre-oxidation. On the other hand, chlorine dioxide leads to the highest production of chlorite and chlorate. The coagulation/flocculation process after pre-oxidation shows that chlorine dioxide demand decreases if potassium permanganate is employed as an oxidant, both with ferric chloride and aluminum sulfate. Therefore, the combination of these processes leads to a lower production of chlorite and chlorate. Aluminum sulfate is preferable in terms of the chlorine dioxide demand reduction and minimization of the chlorite and chlorate formation. Activated carbon is the most effective solution as it reduced the chlorine dioxide consumption by about 50% and the DBP formation by about 20-40%. Copyright © 2014 Elsevier Ltd. All rights reserved.

Intermediate Nucleation State of GaN Growth

Science.gov (United States)

Zheng, L. X.; Xie, M. H.; Tong, S. Y.

2001-03-01

Homoexpitaxial nucleation of GaN during molecular-beam epitaxy is followed by scanning tunneling microcopy (STM). We observe a metastable nucleation state, which manifests as “ghost” islands in STM images. These “ghost” islands can be irreversibly driven into normal islands by continuous STM imaging. It is further established that the “ghost” island formation is related to the presence of excess Ga atoms on the surface: Normal islands are only seen under the N-rich or stoichiometric flux condition, whereas “ghost” islands are observed under Ga-rich conditions. For intermediate excess-Ga coverages, both normal and “ghost” islands are present, however, they show distinctly different sizes, suggesting different nucleation states for the two. A growth model is proposed to account for the formation of metastable, “ghost” islands. Kinetic Monte Carlo simulation is carried out and main features of the surface are reproduced. We acknowledge financial support from HK RGC under grant Nos. 7396/00P, 7142/99P, and 7121/00P.

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.

Deep-sea bioluminescence blooms after dense water formation at the ocean surface.

Directory of Open Access Journals (Sweden)

Christian Tamburini

Full Text Available The deep ocean is the largest and least known ecosystem on Earth. It hosts numerous pelagic organisms, most of which are able to emit light. Here we present a unique data set consisting of a 2.5-year long record of light emission by deep-sea pelagic organisms, measured from December 2007 to June 2010 at the ANTARES underwater neutrino telescope in the deep NW Mediterranean Sea, jointly with synchronous hydrological records. This is the longest continuous time-series of deep-sea bioluminescence ever recorded. Our record reveals several weeks long, seasonal bioluminescence blooms with light intensity up to two orders of magnitude higher than background values, which correlate to changes in the properties of deep waters. Such changes are triggered by the winter cooling and evaporation experienced by the upper ocean layer in the Gulf of Lion that leads to the formation and subsequent sinking of dense water through a process known as "open-sea convection". It episodically renews the deep water of the study area and conveys fresh organic matter that fuels the deep ecosystems. Luminous bacteria most likely are the main contributors to the observed deep-sea bioluminescence blooms. Our observations demonstrate a consistent and rapid connection between deep open-sea convection and bathypelagic biological activity, as expressed by bioluminescence. In a setting where dense water formation events are likely to decline under global warming scenarios enhancing ocean stratification, in situ observatories become essential as environmental sentinels for the monitoring and understanding of deep-sea ecosystem shifts.

Deep-sea bioluminescence blooms after dense water formation at the ocean surface.

Science.gov (United States)

Tamburini, Christian; Canals, Miquel; Durrieu de Madron, Xavier; Houpert, Loïc; Lefèvre, Dominique; Martini, Séverine; D'Ortenzio, Fabrizio; Robert, Anne; Testor, Pierre; Aguilar, Juan Antonio; Samarai, Imen Al; Albert, Arnaud; André, Michel; Anghinolfi, Marco; Anton, Gisela; Anvar, Shebli; Ardid, Miguel; Jesus, Ana Carolina Assis; Astraatmadja, Tri L; Aubert, Jean-Jacques; Baret, Bruny; Basa, Stéphane; Bertin, Vincent; Biagi, Simone; Bigi, Armando; Bigongiari, Ciro; Bogazzi, Claudio; Bou-Cabo, Manuel; Bouhou, Boutayeb; Bouwhuis, Mieke C; Brunner, Jurgen; Busto, José; Camarena, Francisco; Capone, Antonio; Cârloganu, Christina; Carminati, Giada; Carr, John; Cecchini, Stefano; Charif, Ziad; Charvis, Philippe; Chiarusi, Tommaso; Circella, Marco; Coniglione, Rosa; Costantini, Heide; Coyle, Paschal; Curtil, Christian; Decowski, Patrick; Dekeyser, Ivan; Deschamps, Anne; Donzaud, Corinne; Dornic, Damien; Dorosti, Hasankiadeh Q; Drouhin, Doriane; Eberl, Thomas; Emanuele, Umberto; Ernenwein, Jean-Pierre; Escoffier, Stéphanie; Fermani, Paolo; Ferri, Marcelino; Flaminio, Vincenzo; Folger, Florian; Fritsch, Ulf; Fuda, Jean-Luc; Galatà, Salvatore; Gay, Pascal; Giacomelli, Giorgio; Giordano, Valentina; Gómez-González, Juan-Pablo; Graf, Kay; Guillard, Goulven; Halladjian, Garadeb; Hallewell, Gregory; van Haren, Hans; Hartman, Joris; Heijboer, Aart J; Hello, Yann; Hernández-Rey, Juan Jose; Herold, Bjoern; Hößl, Jurgen; Hsu, Ching-Cheng; de Jong, Marteen; Kadler, Matthias; Kalekin, Oleg; Kappes, Alexander; Katz, Uli; Kavatsyuk, Oksana; Kooijman, Paul; Kopper, Claudio; Kouchner, Antoine; Kreykenbohm, Ingo; Kulikovskiy, Vladimir; Lahmann, Robert; Lamare, Patrick; Larosa, Giuseppina; Lattuada, Dario; Lim, Gordon; Presti, Domenico Lo; Loehner, Herbert; Loucatos, Sotiris; Mangano, Salvatore; Marcelin, Michel; Margiotta, Annarita; Martinez-Mora, Juan Antonio; Meli, Athina; Montaruli, Teresa; Moscoso, Luciano; Motz, Holger; Neff, Max; Nezri, Emma Nuel; Palioselitis, Dimitris; Păvălaş, Gabriela E; Payet, Kevin; Payre, Patrice; Petrovic, Jelena; Piattelli, Paolo; Picot-Clemente, Nicolas; Popa, Vlad; Pradier, Thierry; Presani, Eleonora; Racca, Chantal; Reed, Corey; Riccobene, Giorgio; Richardt, Carsten; Richter, Roland; Rivière, Colas; Roensch, Kathrin; Rostovtsev, Andrei; Ruiz-Rivas, Joaquin; Rujoiu, Marius; Russo, Valerio G; Salesa, Francisco; Sánchez-Losa, Augustin; Sapienza, Piera; Schöck, Friederike; Schuller, Jean-Pierre; Schussler, Fabian; Shanidze, Rezo; Simeone, Francesco; Spies, Andreas; Spurio, Maurizio; Steijger, Jos J M; Stolarczyk, Thierry; Taiuti, Mauro G F; Toscano, Simona; Vallage, Bertrand; Van Elewyck, Véronique; Vannoni, Giulia; Vecchi, Manuela; Vernin, Pascal; Wijnker, Guus; Wilms, Jorn; de Wolf, Els; Yepes, Harold; Zaborov, Dmitry; De Dios Zornoza, Juan; Zúñiga, Juan

2013-01-01

The deep ocean is the largest and least known ecosystem on Earth. It hosts numerous pelagic organisms, most of which are able to emit light. Here we present a unique data set consisting of a 2.5-year long record of light emission by deep-sea pelagic organisms, measured from December 2007 to June 2010 at the ANTARES underwater neutrino telescope in the deep NW Mediterranean Sea, jointly with synchronous hydrological records. This is the longest continuous time-series of deep-sea bioluminescence ever recorded. Our record reveals several weeks long, seasonal bioluminescence blooms with light intensity up to two orders of magnitude higher than background values, which correlate to changes in the properties of deep waters. Such changes are triggered by the winter cooling and evaporation experienced by the upper ocean layer in the Gulf of Lion that leads to the formation and subsequent sinking of dense water through a process known as "open-sea convection". It episodically renews the deep water of the study area and conveys fresh organic matter that fuels the deep ecosystems. Luminous bacteria most likely are the main contributors to the observed deep-sea bioluminescence blooms. Our observations demonstrate a consistent and rapid connection between deep open-sea convection and bathypelagic biological activity, as expressed by bioluminescence. In a setting where dense water formation events are likely to decline under global warming scenarios enhancing ocean stratification, in situ observatories become essential as environmental sentinels for the monitoring and understanding of deep-sea ecosystem shifts.

Engineering design study for storage and disposal of intermediate level waste

Energy Technology Data Exchange (ETDEWEB)

Griffin, J R; Hackney, S; Richardson, J A; Heafield, W

1982-11-01

A conceptual design study is presented which covers both the storage and disposal of intermediate level waste; repositories in several rock formations are considered at a 300m depth. A total system is proposed including an engineered trench for ..beta gamma.. waste, emplacement systems and off site transportation. Safety during the emplacement phase and the radiological effects of human intrusion and geological catastrophies are considered.

Evaluation of susceptibility of polymer and rubber materials intended into contact with drinking water on biofilm formation

Science.gov (United States)

Szczotko, Maciej; Stankiewicz, Agnieszka; Jamsheer-Bratkowska, Małgorzata

Plumbing materials in water distribution networks and indoor installations are constantly evolving. The application of new, more economical solutions with plastic materials eliminates the corrosion problems, however, do not fully protect the consumer against secondary microbial contamination of water intended for human consumption caused by the presence of a biofilm on the inner surface of materials applied. National Institute of Public Health - National Institute of Hygiene conducts research aimed at a comprehensive assessment of this type of materials, resulting their further marketing authorization in Poland. Evaluation and comparison of polymer and rubber materials intended to contact with water for the susceptibility to biofilm formation. Plastic materials (polyethylene, polypropylene, polyvinyl chloride) and rubber compounds (EPDM, NBR), from different manufacturers were evaluated. The study was carried out on 37 samples, which were divided into groups according to the material of which they were made. The testing was conducted according to the method based on conditions of dynamic flow of tap water. The level of bioluminescence in swabs taken from the surface of the tested materials was investigated with a luminometer. Evaluation of plastic materials does not show major objections in terms of hygienic assessment. All materials met the evaluation criteria established for methodology used. In case of rubber compounds, a substantial part clearly exceeded the limit values, which resulted in their negative assessment and elimination of these materials from domestic market. High susceptibility to the formation of biofilm in the group of products made of rubber compounds has been demonstrated. Examined plastic materials, except for several cases, do not revealed susceptibility to biofilm formation, but application of plastics for distribution of water intended for human consumption does not fully protect water from secondary, microbiological contamination. Complete

Project Guarantee 1985. Final repository for low- and intermediate-level radioactive wastes: The system of safety barriers

International Nuclear Information System (INIS)

Anon.

1985-01-01

The safety barrier system for the type B repository for low- and intermediate-level waste is described. The barrier parameters which are relevant for safety analysis are quantified and associated error limits and data scatter are given. The aim of the report is to give a summary documentation of the safety analysis input data and their scientific background. For secure containment of radioactive waste safety barriers are used which effectively limit the release of radioactive material from the repository (release barriers) and effectively retard the entry of the original radioactive material into the biosphere (time barriers). In the case of low- and intermediate-level waste the technical safety barrier system comprises: waste solidification matrix (cement, bitumen and resin), immobilisation of the waste packages in containers using liquid cement, concrete repository containers, backfilling of remaining vacant storage space with special concrete, concrete lining of the repository caverns, sealing of access tunnels on final closure of the repository. Natural geological safety barriers - host rock and overlying formations - have the following important functions. Because of its stability, the host rock in the repository zone protects the technical safety barrier system from destruction caused by climatic effects and erosion for a sufficient length of time. It also provides for low water flow and favourable chemistry (reducing conditions)

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.

Intermediality and media change

OpenAIRE

2012-01-01

This book is about intermediality as an approach to analysing and understanding media change. Intermediality and Media Change is critical of technological determinism that characterises 'new media discourse' about the ongoing digitalization, framed as a revolution and creating sharp contrasts between old and new media. Intermediality instead emphasises paying attention to continuities between media of all types and privileges a comparative perspective on technological changes in media over ti...

Kinematic variables and water transport control the formation and location of arc volcanoes.

Science.gov (United States)

Grove, T L; Till, C B; Lev, E; Chatterjee, N; Médard, E

2009-06-04

The processes that give rise to arc magmas at convergent plate margins have long been a subject of scientific research and debate. A consensus has developed that the mantle wedge overlying the subducting slab and fluids and/or melts from the subducting slab itself are involved in the melting process. However, the role of kinematic variables such as slab dip and convergence rate in the formation of arc magmas is still unclear. The depth to the top of the subducting slab beneath volcanic arcs, usually approximately 110 +/- 20 km, was previously thought to be constant among arcs. Recent studies revealed that the depth of intermediate-depth earthquakes underneath volcanic arcs, presumably marking the slab-wedge interface, varies systematically between approximately 60 and 173 km and correlates with slab dip and convergence rate. Water-rich magmas (over 4-6 wt% H(2)O) are found in subduction zones with very different subduction parameters, including those with a shallow-dipping slab (north Japan), or steeply dipping slab (Marianas). Here we propose a simple model to address how kinematic parameters of plate subduction relate to the location of mantle melting at subduction zones. We demonstrate that the location of arc volcanoes is controlled by a combination of conditions: melting in the wedge is induced at the overlap of regions in the wedge that are hotter than the melting curve (solidus) of vapour-saturated peridotite and regions where hydrous minerals both in the wedge and in the subducting slab break down. These two limits for melt generation, when combined with the kinematic parameters of slab dip and convergence rate, provide independent constraints on the thermal structure of the wedge and accurately predict the location of mantle wedge melting and the position of arc volcanoes.

Formation and degradation of ethylenethiourea (ETU) in soil and water under tropical conditions

NARCIS (Netherlands)

Ruiz-Suárez, L.E.; Geissen, V.; Jarquin Sánchez, A.; Castro Chan, R.A.; Bello-Mendoza, R.

2013-01-01

Mancozeb is a fungicide frequently used in tropical countries. It rapidly decomposes into ethylenethiourea (ETU), a more stable and toxic metabolite than mancozeb that is, therefore, regarded as a pollutant of concern. The objective was to study ETU formation and decay kinetics in soil and water

Tracer signals of the intermediate layer of the Arabian Sea

Science.gov (United States)

Rhein, Monika; Stramma, Lothar; Plähn, Olaf

In 1995, hydrographic and chlorofluorocarbon (CFCs, components F11, F12) measurements were carried out in the Gulf of Aden, in the Gulf of Oman, and in the Arabian Sea. In the Gulf of Oman, the F12 concentrations in the Persian Gulf outflow (PGW) at about 300m depth were significantly higher than in ambient surface water with saturations reaching 270%. These high values could not be caused by air-sea gas exchange. The outflow was probably contaminated with oil, and the lipophilic character of the CFCs could then lead to the observed supersaturations. The intermediate F12 maximum decreased rapidly further east and south. At the Strait of Bab el Mandeb in the Gulf of Aden, the Red Sea outflow (RSW) was saturated with F12 to about 65% at 400m depth, and decreased to 50% while descending to 800m depth. The low saturation is not surprising, because the outflow contains deep and intermediate water masses from the Red Sea which were isolated from the surface for some time. The tracer contributions to the Arabian Sea for Indian Central Water (ICW) and PGW are about equal, while below 500m depth the RSW contribution greatly exceeds ICW. Modeling the CFC budget of the Arabian Sea, the inflow of ICW north of 12°N is estimated to be 1-6 Sv, depending mainly on the strength of the flow of Red Sea Water into the Arabian Sea.

Intermediate Fragment

DEFF Research Database (Denmark)

Kruse Aagaard, Anders

2015-01-01

This text and its connected exhibition are aiming to reflect both on the thoughts, the processes and the outcome of the design and production of the artefact ‘Intermediate Fragment’ and making as a contemporary architectural tool in general. Intermediate Fragment was made for the exhibition ‘Enga...... of realising an exhibition object was conceived, but expanded, refined and concretised through this process. The context of the work shown here is an interest in a tighter, deeper connection between experimentally obtained material knowledge and architectural design....

Fluorescence lifetime components reveal kinetic intermediate states upon equilibrium denaturation of carbonic anhydrase II.

Science.gov (United States)

Nemtseva, Elena V; Lashchuk, Olesya O; Gerasimova, Marina A; Melnik, Tatiana N; Nagibina, Galina S; Melnik, Bogdan S

2017-12-21

In most cases, intermediate states of multistage folding proteins are not 'visible' under equilibrium conditions but are revealed in kinetic experiments. Time-resolved fluorescence spectroscopy was used in equilibrium denaturation studies. The technique allows for detecting changes in the conformation and environment of tryptophan residues in different structural elements of carbonic anhydrase II which in its turn has made it possible to study the intermediate states of carbonic anhydrase II under equilibrium conditions. The results of equilibrium and kinetic experiments using wild-type bovine carbonic anhydrase II and its mutant form with the substitution of leucine for alanine at position 139 (L139A) were compared. The obtained lifetime components of intrinsic tryptophan fluorescence allowed for revealing that, the same as in kinetic experiments, under equilibrium conditions the unfolding of carbonic anhydrase II ensues through formation of intermediate states.

Protein Topology Determines Cysteine Oxidation Fate: The Case of Sulfenyl Amide Formation among Protein Families

Science.gov (United States)

Defelipe, Lucas A.; Lanzarotti, Esteban; Gauto, Diego; Marti, Marcelo A.; Turjanski, Adrián G.

2015-01-01

Cysteine residues have a rich chemistry and play a critical role in the catalytic activity of a plethora of enzymes. However, cysteines are susceptible to oxidation by Reactive Oxygen and Nitrogen Species, leading to a loss of their catalytic function. Therefore, cysteine oxidation is emerging as a relevant physiological regulatory mechanism. Formation of a cyclic sulfenyl amide residue at the active site of redox-regulated proteins has been proposed as a protection mechanism against irreversible oxidation as the sulfenyl amide intermediate has been identified in several proteins. However, how and why only some specific cysteine residues in particular proteins react to form this intermediate is still unknown. In the present work using in-silico based tools, we have identified a constrained conformation that accelerates sulfenyl amide formation. By means of combined MD and QM/MM calculation we show that this conformation positions the NH backbone towards the sulfenic acid and promotes the reaction to yield the sulfenyl amide intermediate, in one step with the concomitant release of a water molecule. Moreover, in a large subset of the proteins we found a conserved beta sheet-loop-helix motif, which is present across different protein folds, that is key for sulfenyl amide production as it promotes the previous formation of sulfenic acid. For catalytic activity, in several cases, proteins need the Cysteine to be in the cysteinate form, i.e. a low pKa Cys. We found that the conserved motif stabilizes the cysteinate by hydrogen bonding to several NH backbone moieties. As cysteinate is also more reactive toward ROS we propose that the sheet-loop-helix motif and the constraint conformation have been selected by evolution for proteins that need a reactive Cys protected from irreversible oxidation. Our results also highlight how fold conservation can be correlated to redox chemistry regulation of protein function. PMID:25741692

Governance-Default Risk Relationship and the Demand for Intermediated and Non-Intermediated Debt

Directory of Open Access Journals (Sweden)

Husam Aldamen

2012-09-01

Full Text Available This paper explores the impact of corporate governance on the demand for intermediated debt (asset finance, bank debt, non-bank private debt and non-intermediated debt (public debt in the Australian debt market. Relative to other countries the Australian debt market is characterised by higher proportions of intermediated or private debt with a lower inherent level of information asymmetry in that private lenders have greater access to financial information (Gray, Koh & Tong 2009. Our firm level, cross-sectional evidence suggests that higher corporate governance impacts demand for debt via the mitigation of default risk. However, this relationship is not uniform across all debt types. Intermediated debt such as bank and asset finance debt are more responsive to changes in governance-default risk relationship than non-bank and non-intermediated debt. The implication is that a firm’s demand for different debt types will reflect its governance-default risk profile.

The formation of trihalomethanes in the potabilization of natural and synthetic waters; Formacion de trihalometanos en la potabilizacion de aguas naturales y sinteticas

Energy Technology Data Exchange (ETDEWEB)

Rodriguez Vidal, F.J.; Perez Serrano, A.; Orozco Barrenetxea, C.; Sanllorente, M.C.; Garcia Valverde, M. [Universidad de Burgos. Burgos (Spain)

1998-12-01

One of the main aspects in the control drinking water treatment is the formation of disinfection by-pro-ducts (DBPs), some of the most important are the trihalomethanes (THMs). In order to predict and control the THMs formation is necessary to know the influence of the different parameters involved in their formation and the influence of the different techniques used in drinking water treatment. The objective of this study is to investigate these effects on natural waters (Uzquiza reservoir-Burgos) and synthetic waters (fulvic and humic acids extracted from the mentioned reservoir). (Author) 21 refs.

Stabilization and activation of alpha-chymotrypsin in water-organic solvent systems by complex formation with oligoamines.

Science.gov (United States)

Kudryashova, Elena V; Artemova, Tatiana M; Vinogradov, Alexei A; Gladilin, Alexander K; Mozhaev, Vadim V; Levashov, Andrey V

2003-04-01

Formation of enzyme-oligoamine complexes was suggested as an approach to obtain biocatalysts with enhanced resistance towards inactivation in water-organic media. Complex formation results in broadening (by 20-40% v/v ethanol) of the range of cosolvent concentrations where the enzyme retains its catalytic activity (stabilization effect). At moderate cosolvent concentrations (20-40% v/v) complex formation activates the enzyme (by 3-6 times). The magnitude of activation and stabilization effects increases with the number of possible electrostatic contacts between the protein surface and the molecules of oligoamines (OA). Circular dichroism spectra in the far-UV region show that complex formation stabilizes protein conformation and prevents aggregation in water-organic solvent mixtures. Two populations of the complexes with different thermodynamic stabilities were found in alpha-chymotrypsin (CT)-OA systems depending on the CT/OA ratio. The average dissociation constants and stoichiometries of both low- and high-affinity populations of the complexes were estimated. It appears that it is the low-affinity sites on the CT surface that are responsible for the activation effect.

Worldwide data sets constrain the water vapor uptake coefficient in cloud formation.

Science.gov (United States)

Raatikainen, Tomi; Nenes, Athanasios; Seinfeld, John H; Morales, Ricardo; Moore, Richard H; Lathem, Terry L; Lance, Sara; Padró, Luz T; Lin, Jack J; Cerully, Kate M; Bougiatioti, Aikaterini; Cozic, Julie; Ruehl, Christopher R; Chuang, Patrick Y; Anderson, Bruce E; Flagan, Richard C; Jonsson, Haflidi; Mihalopoulos, Nikos; Smith, James N

2013-03-05

Cloud droplet formation depends on the condensation of water vapor on ambient aerosols, the rate of which is strongly affected by the kinetics of water uptake as expressed by the condensation (or mass accommodation) coefficient, αc. Estimates of αc for droplet growth from activation of ambient particles vary considerably and represent a critical source of uncertainty in estimates of global cloud droplet distributions and the aerosol indirect forcing of climate. We present an analysis of 10 globally relevant data sets of cloud condensation nuclei to constrain the value of αc for ambient aerosol. We find that rapid activation kinetics (αc > 0.1) is uniformly prevalent. This finding resolves a long-standing issue in cloud physics, as the uncertainty in water vapor accommodation on droplets is considerably less than previously thought.

Starting mechanisms and dynamics of bubble formation induced by a Ho:Yttrium aluminum garnet laser in water

Science.gov (United States)

Frenz, Martin; Könz, Flurin; Pratisto, Hans; Weber, Heinz P.; Silenok, Alexander S.; Konov, Vitaly I.

1998-12-01

The starting mechanisms and dynamics of laser-induced bubble formation at a submerged fiber tip in distilled water were experimentally investigated using pressure measurements and fast flash videography. A fiber guided Ho:YAG laser operating in the free running (τ=200 μs) and Q-switched (τ=45 ns) mode at a wavelength of λ=2.12 μm was used as a light source. It is shown that the beam profile at the distal fiber tip (multimode fiber d=300 μm) exhibits hot spots that result in an inhomogeneous temperature distribution in the heated water volume. Depending on the laser irradiance, three different bubble formation processes are distinguished: bubble formation by heating, by rarefraction (cavitation), and by a combination of these two processes. For laser irradiances of less than 0.5 MW/ cm2 bubble formation takes place at temperatures near the critical point of water (T=280 °C). A rapid decrease in the threshold temperature for bubble formation was found for laser irradiances between 0.5 and 1 MW/cm 2. At laser irradiances higher than 3 MW/cm2, microbubbles with radii of up to 20 μm were formed at the front of the laser pulse even though the average water temperature was far below 100 °C. The water temperature distribution during the laser pulse was determined by numerical simulation. Simultaneous pressure measurements revealed that each subablative laser spike induces a bipolar pressure transient. The onset of the bubble expansion was found to be correlated with a characteristic pressure increase that can be used for on-line monitoring of the ablation process. The distortion of the temporal profile of the pressure wave is shown to be an effect of diffraction. The reduction of pressure by the negative part of the bipolar pressure transients leads to a lowering of the evaporation pressure and therefore to the initiation of bubbles by cavitation. With increasing irradiance this mechanism becomes more efficient.

A Free Energy Barrier Caused by the Refolding of an Oligomeric Intermediate Controls the Lag Time of Amyloid Formation by hIAPP.

Science.gov (United States)

Serrano, Arnaldo L; Lomont, Justin P; Tu, Ling-Hsien; Raleigh, Daniel P; Zanni, Martin T

2017-11-22

Transiently populated oligomers formed en route to amyloid fibrils may constitute the most toxic aggregates associated with many amyloid-associated diseases. Most nucleation theories used to describe amyloid aggregation predict low oligomer concentrations and do not take into account free energy costs that may be associated with structural rearrangements between the oligomer and fiber states. We have used isotope labeling and two-dimensional infrared spectroscopy to spectrally resolve an oligomeric intermediate during the aggregation of the human islet amyloid protein (hIAPP or amylin), the protein associated with type II diabetes. A structural rearrangement includes the F 23 G 24 A 25 I 26 L 27 region of hIAPP, which starts from a random coil structure, evolves into ordered β-sheet oligomers containing at least 5 strands, and then partially disorders in the fibril structure. The supercritical concentration is measured to be between 150 and 250 μM, which is the thermodynamic parameter that sets the free energy of the oligomers. A 3-state kinetic model fits the experimental data, but only if it includes a concentration independent free energy barrier >3 kcal/mol that represents the free energy cost of refolding the oligomeric intermediate into the structure of the amyloid fibril; i.e., "oligomer activation" is required. The barrier creates a transition state in the free energy landscape that slows fibril formation and creates a stable population of oligomers during the lag phase, even at concentrations below the supercritical concentration. Largely missing in current kinetic models is a link between structure and kinetics. Our experiments and modeling provide evidence that protein structural rearrangements during aggregation impact the populations and kinetics of toxic oligomeric species.

APEX (Aqueous Photochemistry of Environmentally occurring Xenobiotics): a free software tool to predict the kinetics of photochemical processes in surface waters.

Science.gov (United States)

Bodrato, Marco; Vione, Davide

2014-04-01

The APEX software predicts the photochemical transformation kinetics of xenobiotics in surface waters as a function of: photoreactivity parameters (direct photolysis quantum yield and second-order reaction rate constants with transient species, namely ˙OH, CO₃(-)˙, (1)O₂ and the triplet states of chromophoric dissolved organic matter, (3)CDOM*), water chemistry (nitrate, nitrite, bicarbonate, carbonate, bromide and dissolved organic carbon, DOC), and water depth (more specifically, the optical path length of sunlight in water). It applies to well-mixed surface water layers, including the epilimnion of stratified lakes, and the output data are average values over the considered water column. Based on intermediate formation yields from the parent compound via the different photochemical pathways, the software can also predict intermediate formation kinetics and overall yield. APEX is based on a photochemical model that has been validated against available field data of pollutant phototransformation, with good agreement between model predictions and field results. The APEX software makes allowance for different levels of knowledge of a photochemical system. For instance, the absorption spectrum of surface water can be used if known, or otherwise it can be modelled from the values of DOC. Also the direct photolysis quantum yield can be entered as a detailed wavelength trend, as a single value (constant or average), or it can be defined as a variable if unknown. APEX is based on the free software Octave. Additional applications are provided within APEX to assess the σ-level uncertainty of the results and the seasonal trend of photochemical processes.

Disinfection byproduct formation in drinking water sources: A case study of Yuqiao reservoir.

Science.gov (United States)

Zhai, Hongyan; He, Xizhen; Zhang, Yan; Du, Tingting; Adeleye, Adeyemi S; Li, Yao

2017-08-01

This study investigated the potential formation of disinfection byproducts (DBPs) during chlorination and chloramination of 20 water samples collected from different points of Yuqiao reservoir in Tianjin, China. The concentrations of dissolved organic matter and ammonia decreased downstream the reservoir, while the specific UV absorbance (SUVA: the ratio of UV 254 to dissolved organic carbon) increased [from 0.67 L/(mg*m) upstream to 3.58 L/(mg*m) downstream]. The raw water quality played an important role in the formation of DBPs. During chlorination, haloacetic acids (HAAs) were the major DBPs formed in most of the water samples, followed by trihalomethanes (THMs). CHCl 3 and CHCl 2 Br were the major THM species, while trichloroacetic acid (TCAA) and dichloroacetic acid (DCAA) were the major HAA species. Chloramination, on the other hand, generally resulted in lower concentrations of THMs (CHCl 3 ), HAAs (TCAA and DCAA), and haloacetonitriles (HANs). All the species of DBPs formed had positive correlations with the SUVA values, and HANs had the highest one (R 2  = 0.8). The correlation coefficients between the analogous DBP yields and the SUVA values in chlorinated samples were close to those in chloraminated samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

Formation of ‘Crioula’ guava rootstock under saline water irrigation and nitrogen doses

Directory of Open Access Journals (Sweden)

Leandro de P. Souza

Full Text Available ABSTRACT The objective of this research was to evaluate the growth and formation of fresh and dry weight of ‘Crioula’ guava rootstock irrigated with waters of different saline levels and nitrogen (N doses, in an experiment conducted in plastic tubes under greenhouse conditions. The experimental design was randomized blocks, in a 5 x 4 factorial scheme with four replicates, and the treatments consisted of five levels of water electrical conductivity - ECw (0.3, 1.1, 1.9, 2.7 and 3.5 dS m-1 and four N doses (70, 100, 130 and 160% of the N dose recommended for the cultivation of guava seedlings, cv. ‘Paluma’. The dose referring to 100% corresponds to 773 mg of N dm-3. The highest growth of ‘Crioula’ guava rootstock was obtained with ECw of 0.3 dS m-1 and fertilization of 541.1 mg N dm-3 of soil; increasing N doses did not reduce the deleterious effect of the salt stress on the growth and phytomass formation of ‘Crioula’ guava rootstock; irrigation with water of up to 1.75 dS m-1, in the production of guava rootstocks, promotes acceptable reduction of 10% in growth and quality of the seedlings.

Early Events, Kinetic Intermediates and the Mechanism of Protein Folding in Cytochrome c

Directory of Open Access Journals (Sweden)

David S. Kliger

2009-04-01

Full Text Available Kinetic studies of the early events in cytochrome c folding are reviewed with a focus on the evidence for folding intermediates on the submillisecond timescale. Evidence from time-resolved absorption, circular dichroism, magnetic circular dichroism, fluorescence energy and electron transfer, small-angle X-ray scattering and amide hydrogen exchange studies on the t £ 1 ms timescale reveals a picture of cytochrome c folding that starts with the ~ 1-ms conformational diffusion dynamics of the unfolded chains. A fractional population of the unfolded chains collapses on the 1 – 100 ms timescale to a compact intermediate IC containing some native-like secondary structure. Although the existence and nature of IC as a discrete folding intermediate remains controversial, there is extensive high time-resolution kinetic evidence for the rapid formation of IC as a true intermediate, i.e., a metastable state separated from the unfolded state by a discrete free energy barrier. Final folding to the native state takes place on millisecond and longer timescales, depending on the presence of kinetic traps such as heme misligation and proline mis-isomerization. The high folding rates observed in equilibrium molten globule models suggest that IC may be a productive folding intermediate. Whether it is an obligatory step on the pathway to the high free energy barrier associated with millisecond timescale folding to the native state, however, remains to be determined.

Identification and Spectroscopic Characterization of Nonheme Iron(III) Hypochlorite Intermediates**

Science.gov (United States)

Draksharapu, Apparao; Angelone, Davide; Quesne, Matthew G; Padamati, Sandeep K; Gómez, Laura; Hage, Ronald; Costas, Miquel; Browne, Wesley R; de Visser, Sam P

2015-01-01

FeIII–hypohalite complexes have been implicated in a wide range of important enzyme-catalyzed halogenation reactions including the biosynthesis of natural products and antibiotics and post-translational modification of proteins. The absence of spectroscopic data on such species precludes their identification. Herein, we report the generation and spectroscopic characterization of nonheme FeIII–hypohalite intermediates of possible relevance to iron halogenases. We show that FeIII-OCl polypyridylamine complexes can be sufficiently stable at room temperature to be characterized by UV/Vis absorption, resonance Raman and EPR spectroscopies, and cryo-ESIMS. DFT methods rationalize the pathways to the formation of the FeIII-OCl, and ultimately FeIV=O, species and provide indirect evidence for a short-lived FeII-OCl intermediate. The species observed and the pathways involved offer insight into and, importantly, a spectroscopic database for the investigation of iron halogenases. PMID:25663379

Differential role of calpain-dependent protein cleavage in intermediate and long-term operant memory in Aplysia.

Science.gov (United States)

Lyons, Lisa C; Gardner, Jacob S; Lentsch, Cassidy T; Gandour, Catherine E; Krishnan, Harini C; Noakes, Eric J

2017-01-01

In addition to protein synthesis, protein degradation or protein cleavage may be necessary for intermediate (ITM) and long-term memory (LTM) to remove molecular constraints, facilitate persistent kinase activity and modulate synaptic plasticity. Calpains, a family of conserved calcium dependent cysteine proteases, modulate synaptic function through protein cleavage. We used the marine mollusk Aplysia californica to investigate the in vivo role of calpains during intermediate and long-term operant memory formation using the learning that food is inedible (LFI) paradigm. A single LFI training session, in which the animal associates a specific netted seaweed with the failure to swallow, generates short (30min), intermediate (4-6h) and long-term (24h) memory. Using the calpain inhibitors calpeptin and MDL-28170, we found that ITM requires calpain activity for induction and consolidation similar to the previously reported requirements for persistent protein kinase C activity in intermediate-term LFI memory. The induction of LTM also required calpain activity. In contrast to ITM, calpain activity was not necessary for the molecular consolidation of LTM. Surprisingly, six hours after LFI training we found that calpain activity was necessary for LTM, although this is a time at which neither persistent PKC activity nor protein synthesis is required for the maintenance of long-term LFI memory. These results demonstrate that calpains function in multiple roles in vivo during associative memory formation. Copyright © 2016 Elsevier Inc. All rights reserved.

Groundwater flow reference model of the Meuse/Haute-Marne region: implications on performance analysis of high and intermediate level and long lived radwaste repository in clay formation

International Nuclear Information System (INIS)

Benabderrahmane, H.; Plas, F.; Yven, B.; Cornaton, F.; Perrochet, P.; Kerrou, J.; Stucki, J.; Caloz, P.

2010-01-01

flow conditions at the bottom and at the sides of the model. - Volumetric extraction due to pumping in the Albian aquifer in the Paris region (50'000 m 3 /day). The regional flow model was calibrated with neutral faults against 1255 measured hydraulic heads. Top surface head conditions were evaluated by calibrating the inflow fluxes and the hydraulic conductivity distribution of the outcropping formations using 400 head measurements. The mean discrepancy between the measured and computed values is less than 9 m. At local scale, a reference flow model of the Oxfordian and Dogger aquifers, respectively overlaying and underlaying the Callovo-Oxfordian host formation, is calibrated against measured hydraulic heads at Andra boreholes and the flow fields of these aquifers at sector scale derived from hydrogeologic, geologic and seismic data acquired from the last site investigation campaign (2007-2008). It includes the hydraulically active faults of Marne and Poissons as well as the less active faults of Gondrecourt. The parameterization that characterize the hydrogeological role of these faults leads to the calibration of the flow with a mean discrepancy between computed and measured values less than 3 m. The performance analysis of the repository emplacement within the 250 km 2 Andra site area was carried out using the stationary velocity field of this reference flow model and computing (i) the travel time and cumulative distance of purely advective particle trajectories and (ii) the lifetime expectancy of water molecules crossing the waste repository and migrating by hydro-dispersive motion (advection, dispersion and diffusion) through the 3-D structures towards the outlets of the aquifer system, using the method proposed by Cornaton and Perrochet. The corrosion of metals contained in intermediate level waste under reduced chemical conditions will lead to the production of hydrogen gas during the post closure phase of a radioactive waste repository. A rough

Oxidation of Refractory Benzothiazoles with PMS/CuFe2O4: Kinetics and Transformation Intermediates

KAUST Repository

Zhang, Tao; Chen, Yin; Leiknes, TorOve

2016-01-01

Benzothiazole (BTH) and its derivatives, 2-(methylthio)bezothiazole (MTBT), 2-benzothiazolsulfonate (BTSA) and 2-hydroxybenzothiazole (OHBT), are refractory pollutants ubiquitously existing in urban runoff at relatively high concentrations. Here, we report their oxidation by CuFe2O4-activated peroxomonosulfate (PMS/CuFe2O4), focusing on kinetics and transformation intermediates. These benzothiazoles can be efficiently degraded by this oxidation process which is confirmed to generate mainly sulfate radicals (with negligible hydroxyl-radical formation) under slightly acidic to neutral pH conditions. The molar exposure ratio of sulfate radical to residual PMS (i.e. Rct) of this process is a constant which is related to reaction condition and can be easily determined. Reaction rate constants of these benzothiazoles towards sulfate radical are (3.3 ± 0.3) × 109, (1.4 ± 0.3) × 109, (1.5 ± 0.1) × 109 and (4.7 ± 0.5) × 109 M-1s-1, respectively (pH 7 and 20 oC). Based on Rct and these rate constants, their degradation in the presence of organic matter can be well predicted. A number of transformation products were detected and tentatively identified using triple-quadruple/linear ion trap MS/MS and high-resolution MS. It appears that sulfate radicals attack BTH, MTBT and BTSA on their benzo ring via electron transfer, generating multiple hydroxylated intermediates which are reactive towards common oxidants. For OHBT oxidation, it prefers to break down the thiazole ring. Due to competitions of the transformation intermediates, a minimum PMS/pollutant molar ratio of 10-20 is required for effective degradation. The flexible PMS/CuFe2O4 could be a useful process to remove the benzothiazoles from low DOC waters like urban runoff or polluted groundwater.

Oxidation of Refractory Benzothiazoles with PMS/CuFe2O4: Kinetics and Transformation Intermediates

KAUST Repository

Zhang, Tao

2016-05-04

Benzothiazole (BTH) and its derivatives, 2-(methylthio)bezothiazole (MTBT), 2-benzothiazolsulfonate (BTSA) and 2-hydroxybenzothiazole (OHBT), are refractory pollutants ubiquitously existing in urban runoff at relatively high concentrations. Here, we report their oxidation by CuFe2O4-activated peroxomonosulfate (PMS/CuFe2O4), focusing on kinetics and transformation intermediates. These benzothiazoles can be efficiently degraded by this oxidation process which is confirmed to generate mainly sulfate radicals (with negligible hydroxyl-radical formation) under slightly acidic to neutral pH conditions. The molar exposure ratio of sulfate radical to residual PMS (i.e. Rct) of this process is a constant which is related to reaction condition and can be easily determined. Reaction rate constants of these benzothiazoles towards sulfate radical are (3.3 ± 0.3) × 109, (1.4 ± 0.3) × 109, (1.5 ± 0.1) × 109 and (4.7 ± 0.5) × 109 M-1s-1, respectively (pH 7 and 20 oC). Based on Rct and these rate constants, their degradation in the presence of organic matter can be well predicted. A number of transformation products were detected and tentatively identified using triple-quadruple/linear ion trap MS/MS and high-resolution MS. It appears that sulfate radicals attack BTH, MTBT and BTSA on their benzo ring via electron transfer, generating multiple hydroxylated intermediates which are reactive towards common oxidants. For OHBT oxidation, it prefers to break down the thiazole ring. Due to competitions of the transformation intermediates, a minimum PMS/pollutant molar ratio of 10-20 is required for effective degradation. The flexible PMS/CuFe2O4 could be a useful process to remove the benzothiazoles from low DOC waters like urban runoff or polluted groundwater.

Evidence for sites of methylmercury formation in a flowing water system: Impact of anthropogenic barriers and water management

Energy Technology Data Exchange (ETDEWEB)

Pizarro-Barraza, Claudia [Department of Natural Resources and Environmental Sciences, University of Nevada-Reno, Reno, NV 89557 (United States); Gustin, Mae Sexauer, E-mail: mgustin@cabnr.unr.edu [Department of Natural Resources and Environmental Sciences, University of Nevada-Reno, Reno, NV 89557 (United States); Peacock, Mary [Department of Biology, University of Nevada-Reno, Reno, NV 89557 (United States); Miller, Matthieu [Department of Natural Resources and Environmental Sciences, University of Nevada-Reno, Reno, NV 89557 (United States)

2014-04-01

The Truckee River, California-Nevada, USA is impacted by mercury (Hg) contamination associated with legacy gold mining. In this work, we investigated the potential for hot-spots of methylmercury (MeHg) formation in the river. Mercury concentrations in multiple media were also used to assess the impacts of anthropogenic barriers, restoration, and water management in this flowing water ecosystem. Water samples were collected on a seasonal time step over 3 years, and analyzed for total Hg (THg) and MeHg concentrations, along with a variety of other water quality parameters. In addition, we measured THg and MeHg in sediments, THg in macroinvertebrates, and THg and δ{sup 15}N and δ{sup 13}C concentrations in fish. Differences in stable isotopes and Hg concentrations in fish were applied to understand the mobility of fish in the river. Mercury concentrations of specific macroinvertebrate species were used to identify sites of MeHg production. In general, loads of Hg and nutrients in the river reach above the Reno–Sparks metropolitan area were similar to that reported for pristine systems, while within and below the city, water quality impacts were observed. Fish isotope data showed that in the city reach food resources were different than those upriver and downriver. Based on Hg and isotope data, mobility of the fish in the river is impacted by anthropogenic obstructions and water manipulation. Below the city, particle bound Hg, derived from the legacy mining, continues to be input to the Truckee River. This Hg is deposited in riparian habitats and areas of river restoration, where it is methylated and becomes available to biota. During spring, when flows were highest, MeHg produced and stored in the sediments is mobilized and transported downriver. Fish and macroinvertebrate concentrations increased downriver indicating passive uptake from water. The information presented here could be useful for those doing river restoration and water manipulation in mercury

Evidence for sites of methylmercury formation in a flowing water system: Impact of anthropogenic barriers and water management

International Nuclear Information System (INIS)

Pizarro-Barraza, Claudia; Gustin, Mae Sexauer; Peacock, Mary; Miller, Matthieu

2014-01-01

The Truckee River, California-Nevada, USA is impacted by mercury (Hg) contamination associated with legacy gold mining. In this work, we investigated the potential for hot-spots of methylmercury (MeHg) formation in the river. Mercury concentrations in multiple media were also used to assess the impacts of anthropogenic barriers, restoration, and water management in this flowing water ecosystem. Water samples were collected on a seasonal time step over 3 years, and analyzed for total Hg (THg) and MeHg concentrations, along with a variety of other water quality parameters. In addition, we measured THg and MeHg in sediments, THg in macroinvertebrates, and THg and δ 15 N and δ 13 C concentrations in fish. Differences in stable isotopes and Hg concentrations in fish were applied to understand the mobility of fish in the river. Mercury concentrations of specific macroinvertebrate species were used to identify sites of MeHg production. In general, loads of Hg and nutrients in the river reach above the Reno–Sparks metropolitan area were similar to that reported for pristine systems, while within and below the city, water quality impacts were observed. Fish isotope data showed that in the city reach food resources were different than those upriver and downriver. Based on Hg and isotope data, mobility of the fish in the river is impacted by anthropogenic obstructions and water manipulation. Below the city, particle bound Hg, derived from the legacy mining, continues to be input to the Truckee River. This Hg is deposited in riparian habitats and areas of river restoration, where it is methylated and becomes available to biota. During spring, when flows were highest, MeHg produced and stored in the sediments is mobilized and transported downriver. Fish and macroinvertebrate concentrations increased downriver indicating passive uptake from water. The information presented here could be useful for those doing river restoration and water manipulation in mercury contaminated

Intermediate report on the problems of warm water drainage

International Nuclear Information System (INIS)

1976-01-01

The investigation into the solution of the problems of warm water drainage and its related matters was conducted, and the result was summarized by the warm water drainage sectional committee of the central public nuisance-prevention council entrusted by the Environment Agency. The first section of this report deals with the background of the warm water drainage problems. In December 1970, the environmental pollution prevention act was revised so as to include warm water drainage in the law. The second section deals with the progress of deliberation by the sectional committee. The third section deals with the actual conditions of warm water drainage. The temperature difference at the inlet and outlet of water was 5 to 11 0 C in power plants, 5 to 16 0 C in iron and steel works, 4 to 11 0 C in petroleum refineries, and 7 to 25 0 C in petrochemical plants. The amount of heat energy discharged from power plants was greater than that from the others. Other sections deal with its effects on the living things in water, the forecast of diffusion of warm drainage, the concept of the regulation of warm drainage, and the present countermeasure. Twelve points which require future investigation are listed. They are the change in the phases of living things affected by the change in temperature and flow of warm drainage, the effects on fishery resources, the estimation system for the environmental calorific capacity in the sea, the mechanism of diffusion and the forecasting method for the diffusion range. (Iwakiri, K.)

[Ultrasound induced the formation of nitric oxide and nitrosonium ions in water and aqueous solutions].

Science.gov (United States)

Stepuro, I I; Adamchuk, R I; Stepuro, V I

2004-01-01

Nitric oxide, nitrosonium ions, nitrites, and nitrates are formed in water saturated with air under the action of ultrasound. Nitrosonium ions react with water and hydrogen peroxide to form nitrites and nitrates in sonicated solution, correspondingly. Nitric oxide is practically completely released from sonicated water into the atmosphere and reacts with air oxygen, forming NOx compounds. The oxidation of nitric oxide in aqueous medium by hydroxyl radicals and dissolved oxygen is a minor route of the formation of nitrites and nitrates in ultrasonic field.

Characterization of a structural intermediate of flavivirus membrane fusion.

Directory of Open Access Journals (Sweden)

Karin Stiasny

2007-02-01

Full Text Available Viral membrane fusion proceeds through a sequence of steps that are driven by triggered conformational changes of viral envelope glycoproteins, so-called fusion proteins. Although high-resolution structural snapshots of viral fusion proteins in their prefusion and postfusion conformations are available, it has been difficult to define intermediate structures of the fusion pathway because of their transient nature. Flaviviruses possess a class II viral fusion protein (E mediating fusion at acidic pH that is converted from a dimer to a trimer with a hairpin-like structure during the fusion process. Here we show for tick-borne encephalitis virus that exposure of virions to alkaline instead of acidic pH traps the particles in an intermediate conformation in which the E dimers dissociate and interact with target membranes via the fusion peptide without proceeding to the merger of the membranes. Further treatment to low pH, however, leads to fusion, suggesting that these monomers correspond to an as-yet-elusive intermediate required to convert the prefusion dimer into the postfusion trimer. Thus, the use of nonphysiological conditions allows a dissection of the flavivirus fusion process and the identification of two separate steps, in which membrane insertion of multiple copies of E monomers precedes the formation of hairpin-like trimers. This sequence of events provides important new insights for understanding the dynamic process of viral membrane fusion.

Intermediates detected by visible spectroscopy during the reaction of nitrite with deoxyhemoglobin: the effect of nitrite concentration and diphosphoglycerate.

Science.gov (United States)

Nagababu, Enika; Ramasamy, Somasundaram; Rifkind, Joseph M

2007-10-16

The reaction of nitrite with deoxyhemoglobin (deoxyHb) results in the reduction of nitrite to NO, which binds unreacted deoxyHb forming Fe(II)-nitrosylhemoglobin (Hb(II)NO). The tight binding of NO to deoxyHb is, however, inconsistent with reports implicating this reaction with hypoxic vasodilation. This dilemma is resolved by the demonstration that metastable intermediates are formed in the course of the reaction of nitrite with deoxyHb. The level of intermediates is quantitated by the excess deoxyHb consumed over the concentrations of the final products formed. The dominant intermediate has a spectrum that does not correspond to that of Hb(III)NO formed when NO reacts with methemoglobin (MetHb), but is similar to metHb resulting in the spectroscopic determinations of elevated levels of metHb. It is a delocalized species involving the heme iron, the NO, and perhaps the beta-93 thiol. The putative role for red cell reacted nitrite on vasodilation is associated with reactions involving the intermediate. (1) The intermediate is less stable with a 10-fold excess of nitrite and is not detected with a 100-fold excess of nitrite. This observation is attributed to the reaction of nitrite with the intermediate producing N2O3. (2) The release of NO quantitated by the formation of Hb(II)NO is regulated by changes in the distal heme pocket as shown by the 4.5-fold decrease in the rate constant in the presence of 2,3-diphosphoglycerate. The regulated release of NO or N2O3 as well as the formation of the S-nitroso derivative of hemoglobin, which has also been reported to be formed from the intermediates generated during nitrite reduction, should be associated with any hypoxic vasodilation attributed to the RBC.

Effects of conventional ozonation and electro-peroxone pretreatment of surface water on disinfection by-product formation during subsequent chlorination.

Science.gov (United States)

Mao, Yuqin; Guo, Di; Yao, Weikun; Wang, Xiaomao; Yang, Hongwei; Xie, Yuefeng F; Komarneni, Sridhar; Yu, Gang; Wang, Yujue

2018-03-01

The electro-peroxone (E-peroxone) process is an emerging ozone-based electrochemical advanced oxidation process that combines conventional ozonation with in-situ cathodic hydrogen peroxide (H 2 O 2 ) production for oxidative water treatment. In this study, the effects of the E-peroxone pretreatment on disinfection by-product (DBP) formation from chlorination of a synthetic surface water were investigated and compared to conventional ozonation. Results show that due to the enhanced transformation of ozone (O 3 ) to hydroxyl radicals (OH) by electro-generated H 2 O 2 , the E-peroxone process considerably enhanced dissolved organic carbon (DOC) abatement and significantly reduced bromate (BrO 3 - ) formation compared to conventional ozonation. However, natural organic matter (NOM) with high UV 254 absorbance, which is the major precursors of chlorination DBPs, was less efficiently abated during the E-peroxone process than conventional ozonation. Consequently, while both conventional ozonation and the E-peroxone process substantially reduced the formation of DBPs (trihalomethanes and haloacetic acids) during post-chlorination, higher DBP concentrations were generally observed during chlorination of the E-peroxone pretreated waters than conventional ozonation treated. In addition, because of conventional ozonation or the E-peroxone treatment, DBPs formed during post-chlorination shifted to more brominated species. The overall yields of brominated DBPs exhibited strong correlations with the bromide concentrations in water. Therefore, while the E-peroxone process can effectively suppress bromide transformation to bromate, it may lead to higher formation of brominated DBPs during post-chlorination compared to conventional ozonation. These results suggest that the E-peroxone process can lead to different DBP formation and speciation during water treatment trains compared to conventional ozonation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Prediction of the extent of formation damage caused by water injection

Energy Technology Data Exchange (ETDEWEB)

Al-Homadhi, Emad S. [King Saud Univ., Riyadh (Saudi Arabia). Petroleum Engineering Dept.

2013-06-15

As a general practice water is injected along the O/W contact to maintain reservoir pressure during production. Down hole analysis of the injected water shows that, even after surface treatment, it still can contain a considerable amount of solid particles. These particles can bridge formation pores and cause a considerable reduction in the injectivity. To ensure good injectivity over a longer term, the concentration and size of these solids should not exceed certain limits. In this article core flood tests were carried out to simulate high rate injectors. The injected brine contained solid particles in different concentrations and sizes. Particle concentration was between 5 and 20 ppm and the particle mean size was between 2 and 9 {mu}m. The results were presented as damaging ratio versus pore volume injected. Contrarily to previous studies instead of using experimental results in calibrating or evaluating certain theoretical models, the results in this study were directly fitted to produce equations which can predict the extent of damage caused by injected water by knowing the mean size and concentration of the solid particles contained in that water. (orig.)

MHD intermediate shock discontinuities: Pt. 1

International Nuclear Information System (INIS)

Kennel, C.F.; Blandford, R.D.; Coppi, P.

1989-01-01

Recent numerical investigations have focused attention once more on the role of intermediate shocks in MHD. Four types of intermediate shock are identified using a graphical representation of the MHD Rankine-Hugoniot conditions. This same representation can be used to exhibit the close relationship of intermediate shocks to switch-on shocks and rotational discontinuities. The conditions under which intermediate discontinuities can be found are elucidated. The variations in velocity, pressure, entropy and magnetic-field jumps with upstream parameters in intermediate shocks are exhibited graphically. The evolutionary arguments traditionally advanced against intermediate shocks may fail because the equations of classical MHD are not strictly hyperbolic. (author)

Biomass decomposition in near critical water

International Nuclear Information System (INIS)

Sinag, Ali; Guelbay, Selen; Uskan, Burcin; Canel, Muammer

2010-01-01

Conversion of baby food (taken as model biomass for protein and carbohydrate containing biomass) to the valuable chemicals in near critical water (648 K and 24 MPa) in an autoclave is presented in this work. K 2 CO 3 , Nickel on silica and Zeolith (HZSM-5) are selected as catalysts. A detailed characterization of the aqueous phases is performed by High Pressure Liquid Chromatography, UV-Vis Spectroscopy, Total Organic Carbon Analyser. Solid particles recovered by the experiments are also subjected to Scanning Electron Microscopy analysis. This study determines the effect of reaction conditions on the reactivity of the major biomass component. Acetic, formic and glycolic acid, aldehydes (acetaldehyde, formaldehyde), phenol and phenol derivatives, furfural, methyl furfural, hydroxymethyl furfural are the intermediates found in the aqueous phase. Baby food contains mostly carbohydrates, proteins, a variety of salts and minerals, etc. Thus, the results show the effect of these ingredients on the hydrothermal conversion of biomass. It is found that the formation and degradation pathways of the intermediates are influenced by the biomass structure.

Biomass decomposition in near critical water

Energy Technology Data Exchange (ETDEWEB)

Sinag, Ali, E-mail: sinag@science.ankara.edu.t [Department of Chemistry, Science Faculty, Ankara University, 06100 Besevler, Ankara (Turkey); Guelbay, Selen; Uskan, Burcin; Canel, Muammer [Department of Chemistry, Science Faculty, Ankara University, 06100 Besevler, Ankara (Turkey)

2010-03-15

Conversion of baby food (taken as model biomass for protein and carbohydrate containing biomass) to the valuable chemicals in near critical water (648 K and 24 MPa) in an autoclave is presented in this work. K{sub 2}CO{sub 3}, Nickel on silica and Zeolith (HZSM-5) are selected as catalysts. A detailed characterization of the aqueous phases is performed by High Pressure Liquid Chromatography, UV-Vis Spectroscopy, Total Organic Carbon Analyser. Solid particles recovered by the experiments are also subjected to Scanning Electron Microscopy analysis. This study determines the effect of reaction conditions on the reactivity of the major biomass component. Acetic, formic and glycolic acid, aldehydes (acetaldehyde, formaldehyde), phenol and phenol derivatives, furfural, methyl furfural, hydroxymethyl furfural are the intermediates found in the aqueous phase. Baby food contains mostly carbohydrates, proteins, a variety of salts and minerals, etc. Thus, the results show the effect of these ingredients on the hydrothermal conversion of biomass. It is found that the formation and degradation pathways of the intermediates are influenced by the biomass structure.

Intermediate phases in the formation of the Cu-Ba-Y high-Tc superconductor from xerogel

International Nuclear Information System (INIS)

Arcon, I.; Bele, M.; Hribar, M.; Kodre, A.; Stuhec, M.; Pejovnik, S.; Frahm, R.

1995-01-01

In the synthesis of YBa 2 Cu 3 O 7-x superconductor ceramics by the sol-gel method, yttrium K EXAFS spectra of the intermediate products give evidence of the dynamics of the Y ion in the reaction. Together with previous data on Cu K and Ba L 3 EXAFS, the results give information on the processes in the amorphous phase, complementing the diffraction data on crystallite growth. ((orig.))

Novel CLCN7 compound heterozygous mutations in intermediate autosomal recessive osteopetrosis.

Science.gov (United States)

Okamoto, Nana; Kohmoto, Tomohiro; Naruto, Takuya; Masuda, Kiyoshi; Komori, Takahide; Imoto, Issei

2017-01-01

Osteopetrosis is a heritable disorder of the skeleton that is characterized by increased bone density on radiographs caused by defects in osteoclast formation and function. Mutations in >10 genes are identified as causative for this clinically and genetically heterogeneous disease in humans. We report two novel missense variations in a compound heterozygous state in the CLCN7 gene, detected through targeted exome sequencing, in a 15-year-old Japanese female with intermediate autosomal recessive osteopetrosis.

Grapevine species from varied native habitats exhibit differences in embolism formation/repair associated with leaf gas exchange and root pressure.

Science.gov (United States)

Knipfer, Thorsten; Eustis, Ashley; Brodersen, Craig; Walker, Andrew M; McElrone, Andrew J

2015-08-01

Drought induces xylem embolism formation, but grapevines can refill non-functional vessels to restore transport capacity. It is unknown whether vulnerability to embolism formation and ability to repair differ among grapevine species. We analysed in vivo embolism formation and repair using x-ray computed microtomography in three wild grapevine species from varied native habitats (Vitis riparia, V. arizonica, V. champinii) and related responses to measurements of leaf gas exchange and root pressure. Vulnerability to embolism formation was greatest in V. riparia, intermediate in V. arizonica and lowest in V. champinii. After re-watering, embolism repair was rapid and pronounced in V. riparia and V. arizonica, but limited or negligible in V. champinii even after numerous days. Similarly, root pressure measured after re-watering was positively correlated with drought stress severity for V. riparia and V. arizonica (species exhibiting embolism repair) but not for V. champinii. Drought-induced reductions in transpiration were greatest for V. riparia and least in V. champinii. Recovery of transpiration after re-watering was delayed for all species, but was greatest for V. champinii and most rapid in V. arizonica. These species exhibit varied responses to drought stress that involve maintenance/recovery of xylem transport capacity coordinated with root pressure and gas exchange responses. © 2014 John Wiley & Sons Ltd.

Olfactory host finding, intermediate memory and its potential ecological adaptation in Nasonia vitripennis

Science.gov (United States)

Schurmann, Daria; Collatz, Jana; Hagenbucher, Steffen; Ruther, Joachim; Steidle, Johannes L. M.

2009-03-01

Associative learning of host-associated chemical cues was studied in Nasonia vitripennis, a parasitoid of fly pupae in nests of hole-nesting birds. When females encountered a fly pupa and performed one sequence of host recognition behaviour including drilling the ovipositor into the host in the presence of the artificial odour furfurylheptanoate (FFH), they were afterwards arrested by FFH in olfactometer experiments. The response vanished after 4 days and could be blocked after 3 days by feeding wasps with ethacrynic acid prior and after the training. This indicates the formation of an intermediate form of memory by one host experience in N. vitripennis. Interestingly, the trained wasps avoided odours that were not present during the host encounter, although naive wasps did not react to these odours. This unique behaviour probably causes wasps to focus during host searching on those chemical cues they have experienced in the host environment. Studies in nests of hole-nesting birds revealed that about 30% of all nests contained only one fly pupa, and laboratory studies showed that N. vitripennis females are able to parasitise around 100 fly pupae in their life. It is discussed that under these conditions, the formation of a non-permanent intermediate memory for host-associated odours after one host encounter is adaptive to avoid costs involved with formation and maintenance of memory for misleading cues. The demonstration of associative olfactory learning in N. vitripennis, the first parasitoid species with sequenced genome, opens the gate to study molecular mechanisms of memory formation and its ecological adaptation in parasitoids.

Ketene as a Reaction Intermediate in the Carbonylation of Dimethyl Ether to Methyl Acetate over Mordenite

DEFF Research Database (Denmark)

Rasmussen, Dominik Bjørn; Christensen, Jakob Munkholt; Temel, Burcin

2015-01-01

Unprecedented insight into the carbonylation of dimethyl ether over Mordenite is provided through the identification of ketene (CH2CO) as a reaction intermediate. The formation of ketene is predicted by detailed DFT calculations and verified experimentally by the observation of doubly deuterated ...

Turbulence, aeration and bubble features of air-water flows in macro- and intermediate roughness conditions

Directory of Open Access Journals (Sweden)

Stefano Pagliara

2011-06-01

Full Text Available Free surface flows in macro- and intermediate roughness conditions have a high aeration potential causing the flow characteristics to vary with slopes and discharges. The underlying mechanism of two-phase flow characteristics in macro- and intermediate roughness conditions were analyzed in an experimental setup assembled at the Laboratory of Hydraulic Protection of the Territory (PITLAB of the University of Pisa, Italy. Crushed angular rocks and hemispherical boulders were used to intensify the roughness of the bed. Flow rates per unit width ranging between 0.03 m2/s and 0.09 m2/s and slopes between 0.26 and 0.46 were tested over different arrangements of a rough bed. Analyses were mainly carried out in the inner flow region, which consists of both bubbly and intermediate flow regions. The findings revealed that the two-phase flow properties over the rough bed were much affected by rough bed arrangements. Turbulence features of two-phase flows over the rough bed were compared with those of the stepped chute data under similar flow conditions. Overall, the results highlight the flow features in the inner layers of the two-phase flow, showing that the maximum turbulence intensity decreases with the relative submergence, while the bubble frequency distribution is affected by the rough bed elements.

Distribution of oxygen isotopes in the water masses of Drake Passage and the South Atlantic

Science.gov (United States)

Meredith, Michael P.; Grose, Katie E.; McDonagh, Elaine L.; Heywood, Karen J.; Frew, Russell D.; Dennis, Paul F.

1999-09-01

Measurements of the ratio of stable isotopes of oxygen (18O and 16O) from samples collected on World Ocean Circulation Experiment sections SR1b (eastern Drake Passage) and A11 (Punta Arenas to Cape Town) are used, together with hydrographic data, to deduce information about the formation and variability of South Atlantic and Southern Ocean water masses. The Drake Passage surface waters south of the Polar Front (PF) are isotopically light (δ18O around -0.4‰) owing to the influence of meteoric waters. The salinity and δ18O of the A11 surface waters yield an apparent freshwater end-member which is much isotopically lighter than the local precipitation, thus advection of these waters from farther south dominates over local effects in determining the surface water properties. The Drake Passage section shows unusual proximity of the two main fronts of the Antarctic Circumpolar Current (the PF and Subantarctic Front (SAF)), and we observe cold, fresh, and isotopically light water derived from the temperature-minimum Winter Water at the SAF. This water is of the correct density to freshen the intermediate water north of the SAF and thus play a role in the formation of the comparatively fresh Antarctic Intermediate Water (AAIW) of the South Atlantic. This confirms the role of Antarctic water in forming the South Atlantic variety of AAIW. Across the A11 section the oxygen isotope and salinity data at the AAIW core show very similar traces, with waters in the Malvinas Current loop showing lowest values of both. At the eastern boundary of the South Atlantic, the input of Red Sea Water from east of South Africa is observed via the presence of anomalously isotopically heavy AAIW. We deduce potentially significant temporal variability in the isotopic composition of Weddell Sea Deep Water (WSDW) by comparing the Drake Passage data to earlier data covering the outflow of the Weddell Sea. The A11 data show WSDW consistent with such variability, indicating that its effects could

Insight into Chemistry on Cloud/Aerosol Water Surfaces.

Science.gov (United States)

Zhong, Jie; Kumar, Manoj; Francisco, Joseph S; Zeng, Xiao Cheng

2018-05-15

Cloud/aerosol water surfaces exert significant influence over atmospheric chemical processes. Atmospheric processes at the water surface are observed to follow mechanisms that are quite different from those in the gas phase. This Account summarizes our recent findings of new reaction pathways on the water surface. We have studied these surface reactions using Born-Oppenheimer molecular dynamics simulations. These studies provide useful information on the reaction time scale, the underlying mechanism of surface reactions, and the dynamic behavior of the product formed on the aqueous surface. According to these studies, the aerosol water surfaces confine the atmospheric species into a specific orientation depending on the hydrophilicity of atmospheric species or the hydrogen-bonding interactions between atmospheric species and interfacial water. As a result, atmospheric species are activated toward a particular reaction on the aerosol water surface. For example, the simplest Criegee intermediate (CH 2 OO) exhibits high reactivity toward the interfacial water and hydrogen sulfide, with the reaction times being a few picoseconds, 2-3 orders of magnitude faster than that in the gas phase. The presence of interfacial water molecules induces proton-transfer-based stepwise pathways for these reactions, which are not possible in the gas phase. The strong hydrophobicity of methyl substituents in larger Criegee intermediates (>C1), such as CH 3 CHOO and (CH 3 ) 2 COO, blocks the formation of the necessary prereaction complexes for the Criegee-water reaction to occur at the water droplet surface, which lowers their proton-transfer ability and hampers the reaction. The aerosol water surface provides a solvent medium for acids (e.g., HNO 3 and HCOOH) to participate in reactions via mechanisms that are different from those in the gas and bulk aqueous phases. For example, the anti-CH 3 CHOO-HNO 3 reaction in the gas phase follows a direct reaction between anti-CH 3 CHOO and HNO 3

Intermediate levels of hippocampal activity appear optimal for associative memory formation.

NARCIS (Netherlands)

Liu, X.; Qin, S.; Rijpkema, M.J.P.; Luo, J.; Fernandez, G.S.E.

2010-01-01

BACKGROUND: It is well established that hippocampal activity is positively related to effective associative memory formation. However, in biological systems often optimal levels of activity are contrasted by both sub- and supra-optimal levels. Sub-optimal levels of hippocampal activity are commonly

Metal Phosphates as Intermediate Temperature Proton Conducting Electrolytes

DEFF Research Database (Denmark)

Huang, Yunjie; Li, Q.F.; Pan, Chao

2012-01-01

A series of metal phosphates were synthesized and screened as potential proton conductor electrolytes for fuel cells and electrolysers operational at intermediate temperatures. Among the selected, niobium and bismuth phosphates exhibited a proton conductivity of 10-2 and 10-7 S cm-1, respectively......, under the anhydrous atmosphere at 250 °C, showing close correlation with the presence of hydroxyl groups in the phosphate phases. At the water partial pressure of above 0.6 atm, both phosphates possessed a proton conductivity to a level of above 3 x 10-2 S cm-1. Reasonable stability of the proton...... conductivity was observed under either a constant low water partial pressure or under a humidity cycling test within a period of more than 80 hours....

Multiple generations of high salinity formation water in the Triassic Sherwood Sandstone: Wytch Farm oilfield, onshore UK

International Nuclear Information System (INIS)

Worden, R.H.; Manning, D.A.C.; Bottrell, S.H.

2006-01-01

The origin and heterogeneity of oilfield formation water in the Lower Triassic Sherwood Sandstone at Wytch Farm in the Wessex Basin, UK, have been investigated using production data, detailed water geochemistry and O, S and H stable isotope data. The formation waters are highly saline, NaCl-type brines with TDS values of up to 230,000mg/L. There is a general decrease in salinity from the flanks of the field to the crest with Cl - decreasing from about 136,000 to 109,000mg/L. The Cl/Br ratio of the water shows that salinity was largely derived from the dissolution of Upper Triassic continental evaporites found off-structure to the west and north of the field. The water in the field had a meteoric source although variation in δ 2 H values suggests that there may be meteoric waters of different ages in the oilfield, reflecting recharge under different palaeoclimatic conditions. At the crest of the field, aqueous SO 4 2- resulted from dissolution of anhydrite in the reservoir. In contrast, in other parts of the field there is an indication that some of the dissolved SO 4 2- was derived from oxidation of pyrite at some point on the recharge path of meteoric water to the field. There were two meteoric influx events bringing different Cl - concentrations and different δ 2 H values. The first was probably before the Eocene oil influx and could have occurred in the Lower Cretaceous or early Tertiary. The second meteoric influx event probably occurred after or during oil migration into the Wytch Farm structure since the second meteoric water is found at the flanks of the field adjacent to the regions where salt is found in the stratigraphy. The preservation of heterogeneities in oilfield formation water compositions suggests that there has been little aqueous fluid movement or diffusive flux for over 40 million years. Mass flux has been restricted by density stratification within the aquifer and the very low effective permeability for the aqueous phase in the oil

Relationship between THMs/NDMA formation potential and molecular weight of organic compounds for source and treated water in Shanghai, China.

Science.gov (United States)

An, Dong; Gu, Bin; Sun, Sainan; Zhang, Han; Chen, Yanan; Zhu, Huifeng; Shi, Jian; Tong, Jun

2017-12-15

Molecular weight (MW) distributions in source and treated water in Shanghai, China were investigated to understand the relationship between trihalomethanes formation potential/N-nitrosodimethylamine formation potential (THMFP/NDMAFP) and dissolved organic carbon (DOC) for different MW ranges (30KDa). The result of MW distributions in source water indicated a relationship between THMFP/NDMAFP and DOC such that DOC for 30KDa THMFP was totally removed whereas NDMA according to the results for treated water between DOC and NDMAFP (R 2 =0.94 and 0.93 for sand and GAC filtration, respectively). The results may provide researchers with targeted treatment strategies to destroy, remove, or reduce the occurrence of THMs and NDMA precursors. The findings presented in this study will be of great value in future work for selecting suitable drinking water treatment processes to minimize the formation of disinfection by-products using chlorine or chloramine disinfection. Copyright © 2017 Elsevier B.V. All rights reserved.

Studies of water-in-oil emulsions : testing of emulsion formation in OHMSETT

International Nuclear Information System (INIS)

Fingas, M.; Fieldhouse, B.

2001-01-01

A study was conducted to determine the stability of water-in-oil emulsions in the OHMSETT tank facility. The results were then compared with previous laboratory studies which suggested that the stability of emulsions can be grouped into four categories, stable, unstable, meso-stable and entrained. It has been determined that entrained emulsions can retain oil by viscous forces long enough for interfacial agents, resins and asphaltenes to stabilize the droplets. This paper also described the difference in viscosity between the 4 categories of emulsion stability. The OHMSETT tests were conducted in two series of one week each. The first series of tests were conducted in July and involved 12 experiments on 2 different types of oils which were placed at varying thicknesses on the water. The second set of tests were conducted in November and involved 12 experiments on 6 oils. The rheological properties of the oils were measured and compared to the same oils undergoing emulsification in the laboratory. The oils and water-in-oil states produced were found to have analogous properties between the laboratory and the first set of tests at the OHMSETT facility. All the oils tested produced entrained water-in-oil states in both the laboratory and the test tank. The energy in the two test conditions was found to be similar, with the OHMSETT emulsions similar to one produced in the laboratory at high energies. The second series of tests at OHMSETT did not result in the expected water in-oil- states. This unexpected result was most likely due to the residual surfactant from an earlier dispersant experiment. The study showed that the conditions for emulsion formation are analogous in the OHMSETT tank and in the laboratory tests. The level of energy is considered to be the major variant. It was concluded that the energy levels between the laboratory mixing experiments and the OHMSETT is similar. It was shown that surfactants left over from dispersant testing inhibited the formation

Hydrogen-bonded intermediates and transition states during spontaneous and acid-catalyzed hydrolysis of the carcinogen (+)-anti-BPDE.

Science.gov (United States)

Palenik, Mark C; Rodriguez, Jorge H

2014-07-07

Understanding mechanisms of (+)-anti-BPDE detoxification is crucial for combating its mutagenic and potent carcinogenic action. However, energetic-structural correlations of reaction intermediates and transition states during detoxification via hydrolysis are poorly understood. To gain mechanistic insight we have computationally characterized intermediate and transition species associated with spontaneous and general-acid catalyzed hydrolysis of (+)-anti-BPDE. We studied the role of cacodylic acid as a proton donor in the rate limiting step. The computed activation energy (ΔG‡) is in agreement with the experimental value for hydrolysis in a sodium cacodylate buffer. Both types of, spontaneous and acid catalyzed, BPDE hydrolysis can proceed through low-entropy hydrogen bonded intermediates prior to formation of transition states whose energies determine reaction activation barriers and rates.

Apatite Formation and Biocompatibility of a Low Young's Modulus Ti-Nb-Sn Alloy Treated with Anodic Oxidation and Hot Water.

Directory of Open Access Journals (Sweden)

Hidetatsu Tanaka

Full Text Available Ti-6Al-4V alloy is widely prevalent as a material for orthopaedic implants because of its good corrosion resistance and biocompatibility. However, the discrepancy in Young's modulus between metal prosthesis and human cortical bone sometimes induces clinical problems, thigh pain and bone atrophy due to stress shielding. We designed a Ti-Nb-Sn alloy with a low Young's modulus to address problems of stress disproportion. In this study, we assessed effects of anodic oxidation with or without hot water treatment on the bone-bonding characteristics of a Ti-Nb-Sn alloy. We examined surface analyses and apatite formation by SEM micrographs, XPS and XRD analyses. We also evaluated biocompatibility in experimental animal models by measuring failure loads with a pull-out test and by quantitative histomorphometric analyses. By SEM, abundant apatite formation was observed on the surface of Ti-Nb-Sn alloy discs treated with anodic oxidation and hot water after incubation in Hank's solution. A strong peak of apatite formation was detected on the surface using XRD analyses. XPS analysis revealed an increase of the H2O fraction in O 1s XPS. Results of the pull-out test showed that the failure loads of Ti-Nb-Sn alloy rods treated with anodic oxidation and hot water was greater than those of untreated rods. Quantitative histomorphometric analyses indicated that anodic oxidation and hot water treatment induced higher new bone formation around the rods. Our findings indicate that Ti-Nb-Sn alloy treated with anodic oxidation and hot water showed greater capacity for apatite formation, stronger bone bonding and higher biocompatibility for osteosynthesis. Ti-Nb-Sn alloy treated with anodic oxidation and hot water treatment is a promising material for orthopaedic implants enabling higher osteosynthesis and lower stress disproportion.

First-principles quantum mechanical investigations: Catalytic reactions of furfural on Pd(111) and at the water/Pd(111) interface

Science.gov (United States)

Xue, Wenhua

Bio-oils have drawn more and more attention from scientists as a promising new clean, cheap energy source. One of the most interesting relevant issues is the effect of catalysts on the catalytic reactions that are used for producing bio-oils. Furfural, as a very important intermediate during these reactions, has attracted significant studies. However, the effect of catalysts, including particularly the liquid/solid interface formed by a metal catalyst and liquid water, in the catalytic reactions involving furfural still remains elusive. In this research, we performed ab initio molecular dynamics simulations and first-principles density-functional theory calculations to investigate the atomic-scale mechanisms of catalytic hydrogenation of furfural on the palladium surface and at the liquid/state interface formed by the palladium surface and liquid water. We studied all the possible mechanisms that lead to formation of furfuryl alcohol (FOL), formation of tetrahydrofurfural (THFAL), and formation of tetrahydrofurfurfuryl alcohol (THFOL). We found that liquid water plays a significant role in the hydrogenation reactions. During the reaction in the presence of water and the palladium catalyst, in particular, water directly participates in the hydrogenation of the aldehyde group of furfural and facilitates the formation of FOL by reducing the activation energy. Our calculations show that water provides hydrogen for the hydrogenation of the aldehyde group, and at the same time, a pre-existing hydrogen atom, which is resulted from dissociation of molecular hydrogen (experimentally, molecular hydrogen is always supplied for hydrogenation) on the palladium surface, is bonded to water, making the water molecule intact in structure. In the absence of water, on the other hand, formation of FOL and THFAL on the palladium surface involves almost the same energy barriers, suggesting a comparable selectivity. Overall, as water reduces the activation energy for the formation of FOL

New Parameterizations for Neutral and Ion-Induced Sulfuric Acid-Water Particle Formation in Nucleation and Kinetic Regimes

Science.gov (United States)

Määttänen, Anni; Merikanto, Joonas; Henschel, Henning; Duplissy, Jonathan; Makkonen, Risto; Ortega, Ismael K.; Vehkamäki, Hanna

2018-01-01

We have developed new parameterizations of electrically neutral homogeneous and ion-induced sulfuric acid-water particle formation for large ranges of environmental conditions, based on an improved model that has been validated against a particle formation rate data set produced by Cosmics Leaving OUtdoor Droplets (CLOUD) experiments at European Organization for Nuclear Research (CERN). The model uses a thermodynamically consistent version of the Classical Nucleation Theory normalized using quantum chemical data. Unlike the earlier parameterizations for H2SO4-H2O nucleation, the model is applicable to extreme dry conditions where the one-component sulfuric acid limit is approached. Parameterizations are presented for the critical cluster sulfuric acid mole fraction, the critical cluster radius, the total number of molecules in the critical cluster, and the particle formation rate. If the critical cluster contains only one sulfuric acid molecule, a simple formula for kinetic particle formation can be used: this threshold has also been parameterized. The parameterization for electrically neutral particle formation is valid for the following ranges: temperatures 165-400 K, sulfuric acid concentrations 104-1013 cm-3, and relative humidities 0.001-100%. The ion-induced particle formation parameterization is valid for temperatures 195-400 K, sulfuric acid concentrations 104-1016 cm-3, and relative humidities 10-5-100%. The new parameterizations are thus applicable for the full range of conditions in the Earth's atmosphere relevant for binary sulfuric acid-water particle formation, including both tropospheric and stratospheric conditions. They are also suitable for describing particle formation in the atmosphere of Venus.

Review of Global Ocean Intermediate Water Masses: 1.Part A,the Neutral Density Surface (the 'McDougall Surface') as a Study Frame for Water-Mass Analysis

Institute of Scientific and Technical Information of China (English)

Yuzhu You

2006-01-01

This review article commences with a comprehensive historical review of the evolution and application of various density surfaces in atmospheric and oceanic studies.The background provides a basis for the birth of the neutral density idea.Attention is paid to the development of the neutral density surface concept from the nonlinearity of the equation of state of seawater.The definition and properties of neutral density surface are described in detail as developed from the equations of state of seawater and the buoyancy frequency when the squared buoyancy frequency N2 is zero, a neutral state of stability.In order to apply the neutral density surface to intermediate water-mass analysis, this review also describes in detail its practical oceanographic application.The mapping technique is focused for the first time on applying regularly gridded data in this review.It is reviewed how a backbone and ribs framework was designed to flesh out from a reference cast and first mapped the global neutral surfaces in the world's oceans.Several mapped neutral density surfaces are presented as examples for each world ocean.The water-mass property is analyzed in each ocean at mid-depth.The characteristics of neutral density surfaces are compared with those of potential density surfaces.

Disinfection aboard cruise liners and naval units: formation of disinfection by-products using chlorine dioxide in different qualities of drinking water.

Science.gov (United States)

Ufermann, Petra; Petersen, Hauke; Exner, Martin

2011-12-01

The world-wide deployment of cruise liners and naval units has caused an increased need for the disinfection of drinking water. The main cause for this is the unknown quality of drinking water in foreign harbours--besides the formation of bio-films due to the climatically disadvantageous conditions in the operational area. Water conduits on board are currently disinfected with calcium hypochlorite in case of microbiological contamination. Chemical and physical analyses after disinfection with calcium hypochlorite have shown that organic by-products consisting of trihalomethanes develop in considerable amounts during disinfection. Furthermore, the method is susceptible to handling errors and thus often leads to insufficient disinfection results. Hitherto, the use of other disinfection methods allowed by government regulations, especially chlorine dioxide, is not widely spread. Unlike disinfection with calcium hypochlorite, chlorine dioxide does not lead to the formation of trihalomethanes. Typical disinfection by-products (DBP) are the anions chlorite and chlorate, which are formed in oxidative processes. The formation conditions of these anions have not yet been elucidated. For this reason, the probability of the generation of inorganic by-products after disinfection with chlorine dioxide has been determined, and their occurrence in drinking water on board has been examined with respect to a possible correlation between water quality and the formation of chlorate and chlorite. Therefore, a chromatographic method was developed and validated in order to determine the periodical development of chlorate and chlorite from chorine dioxide in purified water at different pH-values as well as in actual drinking water samples from water conduits on board. The formation of the by-products chlorite and chlorate after disinfection with chlorine dioxide is influenced neither by pH-value nor by chemical properties of the disinfected water. Considering the examined conditions