Constant Cl Research Articles

Exploring the pore fluid origin and methane-derived authigenic carbonate properties in response to changes in the methane flux at the southern Ulleung Basin, South Korea

We investigated the geochemistry of gas, pore fluid, and methane-derived authigenic carbonate (MDAC) from four sites in the southern Ulleung Basin, South Korea. In contrast to Sites 16GH-P1 and 16GH-P5, Sites 16GH-P3, and 16GH-P4 are characterized by acoustic chimney structures associated with gas flux. The composition of gas and isotopic signatures of methane (CH4) (C1/C2+ > 300, δ13CCH4 < -60‰, δDCH4 ≤ -190‰) indicate microbial source CH4 at all sites. The upward migration of CH4 can affect the chemical and isotopic properties of pore fluid and gas-related byproducts (e.g., gas hydrate (GH) and MDAC) within the shallow sediments including the current sulfate-methane transition (SMT) (< 5 meters below seafloor). Although no GH was found, elevated Cl- concentrations (maximum = 609 mM) with low δD and δ18O values in Site 16GH-P4 pore fluids delineate the influence of massive GH formation in deeper sediment. In contrast, relatively constant Cl-, δD, and δ18O values in fluids from Sites 16GH-P1, 16GH-P3, and 16GH-P5 indicate a predominant origin from seawater. Pore fluids also exhibit higher concentrations of H4SiO4, B, Mg2+, and K+, along with increasing alkalinity compared to seawater. These observations suggest that marine silicate weathering alters fluid chemistry within the sediment, affecting element and carbon cycles. High alkalinity (up to 60 mM) and Mg2+/Ca2+ ratios (> 6) alongside decreasing Ca2+ and Sr2+ concentrations imply carbonate precipitation. MDACs with diverse morphologies, mainly composed of aragonite and magnesian calcite, and characterized by low carbon isotopic values (δ13CMDAC < -31.3‰), were found at Sites 16GH-P3 and 16GH-P4. Interestingly, δ13CMDAC values at Site 16GH-P3 are clearly differentiated above and below the current SMT. High δ13CMDAC values above the SMT (> -34.3‰) suggest the combined influence of seawater and CH4 migrating upward on MDAC precipitation, whereas low δ13CMDAC values below it (< -41.6‰) indicate a predominant impact of CH4 on MDAC formation. Additionally, the vertical variation of δ18OMDAC values at Site 16GH-P4, compared to the theoretical values, reflects an association with GH dissociation and formation. Our findings improve the understanding of fluid, gas, and MDAC geochemistry in continental margin cold seeps, providing insights into global carbon and element cycles.

A model for the momentum flux parameters of the 1D Two-Fluid Model in vertical annular flows: Linear stability and numerical analysis

The 1D Two-Fluid model is based on an area average process of the time and phase averaged Two-Fluid conservation equations to render the model tractable for industrial scale problems. Due to the averaging processes, the loss of information renders the standard model ill-posed for certain configurations, i.e., short wavelengths disturbances are amplified at an unbounded rate and unphysical solutions are obtained. Closure relations play a key role in this problem, since they are required to close the 1D system and they reintroduce missing physical parameters that may stabilize the flow and render the model well-posed. Two formulations for the liquid momentum flux parameter (CL) for vertical annular flows are proposed based on local velocities distributions. Differential viscous Kelvin-Helmholtz and von Neumann stability analyses are performed to evaluate the proposed CL formulations and three dynamic pressure models. Results have shown that dynamic pressure closure models introduce a small additional amount of damping into the growth rate curves, without a significant change in the hyperbolicity of the system. On the other hand, the novel CL models can guarantee well posedness of the linear system by introducing a growth rate plateau, blocking the unbounded growth of instabilities. Numerical simulations were also performed, and numerical dispersion relations were extracted from the results showing good agreement against LST data, validating the methodology. The novel CLmodels are evaluated against a large experimental database from the literature, showing that the proposed models outperform the standard constant CL values for both pressure drop and liquid film thickness.

Chloride binding of monosulfate hydrate (AFm) and its effect on steel corrosion in simulated concrete pore solution

The impact of monosulfate hydrate (AFm) on chloride (Cl−) binding and steel corrosion in simulated concrete pore solutions (SCPSs) was evaluated. In the SCPS with AFm added, a high concentration of Cl− promoted the Cl− binding amount per unit AFm without producing Kuzel's salt. The Cl− binding capacity of AFm could be improved by appropriately changing the amount of AFm with a constant Cl− concentration. The addition of AFm to the SCPS shortened the passivation time and created a more stable passivation film of the steel. The SO42− produced by the AFm binding with Cl− preferentially reacted with AFm to form AFt, and it affected the stability of the Friedel's salt to release Cl−. The addition of AFm raised the chloride threshold value (CTV) for steel corrosion. However, after reaching the CTV, the corrosion rate of steels increased dramatically, due to the release of the bound Cl−.

On the number of real eigenvalues of a product of truncated orthogonal random matrices

Let O be chosen uniformly at random from the group of (N+L)×(N+L) orthogonal matrices. Denote by O˜ the upper-left N×N corner of O, which we refer to as a truncation of O. In this paper we prove two conjectures of Forrester, Ipsen and Kumar (2020) on the number of real eigenvalues NR(m) of the product matrix O˜1…O˜m, where the matrices {O˜j}j=1m are independent copies of O˜. When L grows in proportion to N, we prove that E(NR(m))= 2mL πarctanh N N+L+O(1),N→∞. We also prove the conjectured form of the limiting real eigenvalue distribution of the product matrix. Finally, we consider the opposite regime where L is fixed with respect to N, known as the regime of weak non-orthogonality. In this case each matrix in the product is very close to an orthogonal matrix. We show that E(NR(m))∼cL,mlog(N) as N→∞ and compute the constant cL,m explicitly. These results generalise the known results in the one matrix case due to Khoruzhenko, Sommers and Życzkowski (2010).

High Time Resolution Analysis of Voltage-Dependent and Voltage-Independent Calcium Sparks in Frog Skeletal Muscle Fibers.

In amphibian skeletal muscle calcium (Ca2+) sparks occur both as voltage-dependent and voltage-independent ligand-activated release events. However, whether their properties and their origin show similarities are still in debate. Elevated K+, constant Cl– content solutions were used to initiate small depolarizations of the resting membrane potential to activate dihydropyridine receptors (DHPR) and caffeine to open ryanodine receptors (RyR) on intact fibers. The properties of Ca2+ sparks observed under control conditions were compared to those measured on depolarized cells and those after caffeine treatment. Calcium sparks were recorded on intact frog skeletal muscle fibers using high time resolution confocal microscopy (x-y scan: 30 Hz). Sparks were elicited by 1 mmol/l caffeine or subthreshold depolarization to different membrane potentials. Both treatments increased the frequency of sparks and altered their morphology. Images were analyzed by custom-made computer programs. Both the amplitude (in ΔF/F0; 0.259 ± 0.001 vs. 0.164 ± 0.001; n = 24942 and 43326, respectively; mean ± SE, p < 0.001) and the full width at half maximum (FWHM, in μm; parallel with fiber axis: 2.34 ± 0.01 vs. 1.92 ± 0.01, p < 0.001; perpendicular to fiber axis: 2.08 ± 0.01 vs. 1.68 ± 0.01, p < 0.001) of sparks was significantly greater after caffeine treatment than on depolarized cells. 9.8% of the sparks detected on depolarized fibers and about one third of the caffeine activated sparks (29.7%) overlapped with another one on the previous frame on x-y scans. Centre of overlapping sparks travelled significantly longer distances between consecutive frames after caffeine treatment then after depolarization (in μm; 1.66 ± 0.01 vs. 0.95 ± 0.01, p < 0.001). Our results suggest that the two types of ryanodine receptors, the junctional RyRs controlled by DHPRs and the parajunctional RyRs are activated independently, using alternate ways, with the possibility of cooperation between neighboring release channels.

Experimental and numerical investigation on flow characteristics of inter-wrapper channel in LMFBR

In this paper, both experimental and numerical methods were adopted to study the flow characteristics of inter-wrapper channel in LMFBR. The minimum repeating unit of inter-wrapper channel was selected as the research object of experimental and numerical study.Experimental investigation of friction factors in the inter-wrapper channel with the aspect ratio (a/b) of 0.09 was performed. The working fluid is deionized water and the experiment was performed at the mass flow rate between 0.025 ~ 0.361 kg/s, and the temperature between 20 ~ 25 °C. The Reynolds number of the test section covers the range of 500 ~ 7500. Numerical analyses were used to study the flow characteristics of inter-wrapper channels with different aspect ratios at laminar and turbulent regime. In laminar regime, one sixth of the cross section of the flow channel was chosen as research object because of symmetry. A universal laminar pressure drop correlation for inter-wrapper flow channels with different aspect ratios was obtained by numerical calculations. In turbulent regime, a CFD analysis was carried out to investigate the flow characteristics of seven inter-wrapper channels with different aspect ratios.The numerical results were in good agreement with experimental results when the aspect ratio a/b is 0.09, which indicates the accuracy of the numerical methods. The laminar flow characteristics of the inter-wrapper channel are completely different from the rectangular channel. The constant Cl of the inter-wrapper channel increases with the increase of aspect ratio a/b. In turbulent regime, the constant Ct is about 0.3342 when the aspect ratio is less than 0.16. It seems to be relatively insensitive to the change of the aspect ratio. Sadatomi's correlation is also applicable to inter-wrapper channels.

Immunex Corp. v. Sandoz Inc. United States Court of Appeals of the Federal Circuit, 2020 964 F.3d 1049

Immunex Corp. v. Sandoz Inc. United States Court of Appeals of the Federal Circuit, 2020 964 F.3d 1049

Origin and evolution of Cl in CO2-rich thermal and mineral waters from northern Portugal

The origin and evolution of the CO2-rich mineral waters from the Vilarelho da Raia, Chaves, Vidago and Pedras Salgadas areas (N-Portugal) has been studied in detail in the past. However, little attention has been paid to the geochemistry (both concentration and isotope) of chlorine as the chloride concentration in the mineral waters was only about 1% of the total dissolved load. As chloride is relevant to the origin and evolution of mineral waters the data obtained in earlier investigations are reinterpreted in this study in order to use Cl geochemistry to improve our knowledge on the origin of Cl in the hot (≈77 °C) and cold (≈17 °C) Na–HCO3–CO2-rich mineral waters that discharge in this region. Chloride is a good tracer of water-rock interaction and presents a strong correlation with the dominant cation sodium. This suggests that chloride present in the mineral waters, despite its small concentration, originates from water-granitic rock interaction. Mineral waters from the different locations show slightly different Cl isotope characteristics. This indicates that not all Cl is originated from water-rock interaction from the granites, as more constant Cl isotope variations would be expected from this process. Due to the deep seated (even mantle) origin of (part of) the He and CO2 in the mineral waters, it is reasonable to conclude that Cl could probably be of mantle origin. This is further suggested by the relative depletion of 37Cl in the mineral waters from the Vidago area presenting higher Cl concentrations.

Biogeochemical cycles at the sulfate-methane transition zone (SMTZ) and geochemical characteristics of the pore fluids offshore southwestern Taiwan

In this study, we used pore water dissolved inorganic carbon (DIC), SO42−, Ca2+ and Mg2+ gradients at the sulfate-methane transition zone (SMTZ) to estimate biogeochemical fluxes for cored sediments collected offshore SW Taiwan. Net DIC flux changes (ΔDIC-Prod) were applied to determine the proportion of sulfate consumption by organic matter oxidation (heterotrophic sulfate reduction) and anaerobic oxidation of methane (AOM), and to determine reliable CH4 fluxes at the SMTZ. Our results show that SO42− profiles are mainly controlled by AOM rather than heterotrophic sulfate reduction. Refinement of CH4 flux estimates enhance our understanding of methane abundance from deep carbon reservoirs to the SMTZ. Concentrations of chloride (Cl−), bromide (Br−) and iodide (I−) dissolved in pore water were used to identify potential sources that control fluid compositions and the behavior of dissolved ions. Constant Cl− concentrations throughout ∼30m sediment suggest no influence of gas hydrates for the compositions within the core. Bromide (Br−) and Iodine (I−) concentrations increase with sediment depth. The I−/Br− ratio appears to reflect organic matter degradation. SO42− concentrations decrease with sediment depth at a constant rate, and sediment depth profiles of Br− and I− concentrations suggests diffusion as the main transport mechanism. Therefore diffusive flux calculations are reasonable. Coring sites with high CH4 fluxes are more common in the accretionary wedge, amongst thrust faults and fractures, than in the passive continental margin offshore southwestern Taiwan. AOM reactions are a major sink for CH4 passing upward through the SMTZ and prevent high methane fluxes in the water column and to the atmosphere.

Efficacy and toxicity of once versus twice daily regimens of amikacin in febrile neutropenic pediatric cancer patients

PurposeTo compare the pharmacokinetic profile, clinical efficacy and toxicity of once-daily dosing of amikacin compared to twice-daily dosing among pediatric cancer patients with fever and neutropenia. Methods134 pediatric patients with hematological malignancies were randomly assigned to receive 15mg/kg/day amikacin intravenously, either once or twice-daily dosing. For pharmacokinetics, two blood samples were obtained from each patient, the first sample was taken after 1h from the beginning of infusion and the second sample was taken after 3h from the first sample. Treatment success was considered when the patient improved without a change in the assigned antibiotic regimen or mortality from infection. Nephrotoxicity was assessed by following the increase in serum creatinine level. ResultsPharmacokinetic data revealed superiority in once-daily dosing where maximum concentration Cmax, area under the concentration time curve in 24h AUC24 and elimination half-life t1/2 were a significantly higher while minimum concentration Cmin, elimination rate constant Ke and clearance CL were significantly lower in once-daily dosing compared to the twice-daily dosing. Clinical response achieved in 76.8% in once-daily group compared to 69.2% in twice-daily group. Nephrotoxicity was recorded in two patients in once-daily group and six patients in the twice-daily group. After stratifying our patients according to age, a significant increase was observed in the volume of distribution V and CL in pediatrics with age ⩽five compared to >five years. Cmax and AUC24 were significantly lower in the age group of ⩽five years. ConclusionsClinical efficacy and nephrotoxicity were slightly improved in once-daily dosing compared to twice-daily dosing.

Apatite as probe for the halogen composition of metamorphic fluids (Bamble Sector, SE Norway)

Halogen composition of replaced apatite formed during a regional metasomatic event (Bamble Sector, SE Norway) reveals information about the composition and evolution of the hydrothermal fluid. Infiltration and pervasive fluid flow of highly saline fluids into gabbroic bodies lead to scapolitization and amphibolitization, where magmatic Cl-rich apatite reacts with the hydrothermal fluid to form OH- and/or F-rich apatite. Apatite from highly altered samples adjacent to the shear zone has highest F (up to 15,000 µg/g) and lowest Br (4–25 µg/g) concentrations, whereas apatite from least altered samples has very low F (30–200 µg/g) and high Br (30–85 µg/g). In addition, individual replaced apatite grains show a zonation in F with high concentrations along rims and cracks and low F in core regions. Iodine concentrations remain rather constant as low values of 0.18–0.70 µg/g. We interpret all observed compositional features of replaced apatite to be the result of a continuous evolution of the fluid during fluid–rock interaction. Due to its high compatibility, F from the infiltrating fluid is incorporated early into recrystallized apatite (close to shear zone and rims of individual apatite grains). In contrast, Br as an incompatible halogen becomes enriched in the fluid and is highest in the most evolved fluid. Using experimental partition data between replaced apatite and fluid, we calculated F concentrations of the evolving fluid to decrease from 60 to <1 µg/g and Br to increase from ~1200 to ~5000 µg/g; I concentrations of the fluid are constant in the order of 370 µg/g. Although Cl is expected to show a similar behavior as Br, replaced apatite has constant Cl concentrations throughout the alteration sequence (~1 wt.%), which is likely the result of a rather constant Cl activity in the fluid. Chlorine stable isotope values of individual apatite grains are heterogeneous and range from −1.2 to +3.7 ‰. High δ 37Cl values are generally correlated with OH-rich zones of replaced apatite, whereas low δ 37Cl values are measured in F-rich zones of replaced apatite and in Cl-apatite of probably magmatic origin. Though apatite δ 37Cl values follow the general bulk trend, the individual δ 37Cl signature seems to reflect the highly localized composition of interfacial fluid at the reaction front. Our observations suggest that apatite can be used as a fluid probe for F, Br, and I to detect a compositional evolution of the fluid, which can be quantified by using experimentally derived partition coefficients. Partitioning of Cl and Cl stable isotopes between highly saline fluids and apatite is complex and likely controlled by more unknown factors than just the Cl concentration.

Analysis of lift and drag coefficients of a GT2 racing car at various speeds with movable wheels and ground

The paper proposes a study of a GT2 racing car with a computational fluid dynamic (CFD) tool. Results of STAR-CCM+ simulations of the flow around the car in a wind tunnel with movable ground and wheels are presented for different air speeds to assess the different contributions of pressure and shear to lift and drag over the speed range. The rear wing contributes more than 85% of the lift force and 7-8% of the drag force for this particular class of racing cars. When reference is made to the low speed drag and lift coefficients, increasing the speed from 25 to 100 m/s produces an increase of CD of more than 3% and a reduction of CL of more than 2%. The resultsuggests modifying the constant CD and CL values used in lap time simulation toolsintroducing the tabulated values to interpolate vs. the speed of the car.

Interpreting Ion-Specific Effects on the Reduction of an Arenediazonium Ion by t-Butylhydroquinone (TBHQ) Using the Pseudophase Kinetic Model in Emulsions Prepared with a Zwitterionic Sulfobetaine Surfactant

Specific salt effects on the reduction of an amphiphilic arenediazonium ion, 16-ArN2(+), by TBHQ in opaque, stirred, and kinetically stable emulsions prepared with a zwitterionic sulfobetaine surfactant are consistent with the chameleon effect: selective anion binding/induced cation binding in the interfacial region of the emulsions. Added NaX salts with different anions decrease the observed first-order rate constant, k(obs), for the reduction in the order X(-) = ClO4(-) > Br(-) ≈ CCl3CO2(-) > Cl(-) > MeSO3(-). Added MCln salts of increasing cation valence at constant total Cl(-) concentration increase kobs in the order M(n+) = Cs(+) < Ca(2+) < Al(3+) in the same emulsions. These results, combined with recent results for nonionic and ionic emulsions, demonstrate that pseudophase kinetic models provide general, coherent explanations of chemical reactivity in homogeneous micelles, microemulsions, vesicles, and now biphasic emulsions and with all types of basic surfactant structures: nonionic, cationic, anionic, and now zwitterionic.

A form of feasible interpolation for constant depth Frege systems

AbstractLet L be a first-order language and Φ and Ψ two L-sentences that cannot be satisfied simultaneously in any finite L-structure. Then obviously the following principle ChainL,Φ,Ψ(n, m) holds: For any chain of finite L-structures C1, …, Cm with the universe [n] one of the following conditions must fail:For each fixed L and parameters n, m the principle ChainL,Φ,Ψ(n,m) can be encoded into a propositional DNF formula of size polynomial in n, m.For any language L containing only constants and unary predicates we show that there is a constant CL such that the following holds: If a constant depth Frege system in DeMorgan language proves ChainL,Φ,Ψ(n, cL . n) by a size s proof then the class of finite L-structures with universe [n] satisfying Φ can be separated from the class of those L-structures on [n] satisfying ψ by a depth 3 formula of size 2log(S)O(1) and with bottom fan-in log(S)O(1).

Quadrupole order in clathrate compound Pr3Pd20Si6

In order to investigate ordered phases revealed at low temperatures in clathrate compound Pr3Pd20Si6, we have performed ultrasonic measurements using a single crystal in magnetic fields at low temperatures. Temperature dependence of elastic constant C11 and CL[11̄0] = (C11 + C12 + 2C44)/2 shows the anomalies at about 150 mK in zero field. Magnetic phase diagrams are determined by measuring C11 in H || [001] and CL[l1̄0] in H || [111]. The magnetic phase diagrams along the three principal axes indicate a closed loop and a strong magnetic anisotropy. This result suggests that antiferroquadrupole ordering appears at low temperatures in Pr3Pd20Si6.

Solubility of H 2O- and chlorine-bearing fluids in basaltic melt of Mount Etna at T = 1050–1250 °C and P = 200 MPa

An experimental study on the solubility of H–O–Cl-bearing fluids in basaltic melts has been conducted at total pressure of 200 MPa, in the temperature range from 1050 to 1250 °C and at redox conditions corresponding to lof fO 2 ∼ QFM + 1 (QFM = quartz–fayalite–magnetite oxygen buffer). A natural trachybasaltic sample of Mount Etna's July–August 2001 eruption has been used as starting material. Water concentrations in the melt (H 2O melt) increase from 4.6 up to 5.4 wt.% with an increase in Cl concentration in the melt (Cl melt) from 0 to 2.5 wt.%. The H 2O melt dramatically decreases to ∼ 2–3 wt.% at Cl melt > 2.5 wt.%. The saturation of the melt with Cl is reached at 4 wt.% Cl melt which is significantly higher than predicted by the existing models. Although increasing total Cl concentration in the system (bulk Cl in fluid and melt) leads to significant extraction of cations like Na, K and Fe from the melt into the fluid(s), the observed systematic increase in H 2O melt cannot be directly attributed to the change in melt composition, indicating that the presence of Cl may decrease the activity coefficient of dissolved H 2O in the melt. The complex non-linear relationships between H 2O and Cl concentrations in basaltic melt and fluid phase point to a strong non-ideality of mixing between fluid components, presumably resulting in an increase in the activity coefficient of Cl in the fluid and in the formation of two fluid phases (vapor and liquid) at the studied conditions. The effect of temperature on the solubility of H–O–Cl-bearing fluids in trachybasaltic melt and, hence, on the mixing properties of the fluid phase is not resolved from the obtained experimental data. The experimentally determined partition coefficient of Cl between fluid(s) and melt ( K d′Cl, based on a molar ratio) exponentially increases from 0.04 up to 14 with increasing Cl melt and shows almost linear dependence on bulk Cl content of the fluid(s). The K d′Cl values < 1 are observed at Cl melt lower than 1.0 wt.%, explaining the almost constant Cl concentrations (∼ 0.2 wt.%) in melt inclusions and variations of H 2O/Cl and S/Cl ratios in melt inclusions and volcanic gasses with ongoing magma degassing and changes in eruptive activity of Mt. Etna. Thus, the obtained data represent an experimental database necessary for the accurate modeling of natural processes of magma degassing at basaltic volcanoes.

Chloride Homeostasis in Saccharomyces cerevisiae: High Affinity Influx, V-ATPase-dependent Sequestration, and Identification of a Candidate Cl− Sensor

Chloride homeostasis in Saccharomyces cerevisiae has been characterized with the goal of identifying new Cl− transport and regulatory pathways. Steady-state cellular Cl− contents (∼0.2 mEq/liter cell water) differ by less than threefold in yeast grown in media containing 0.003–5 mM Cl−. Therefore, yeast have a potent mechanism for maintaining constant cellular Cl− over a wide range of extracellular Cl−. The cell water:medium [Cl−] ratio is >20 in media containing 0.01 mM Cl− and results in part from sequestration of Cl− in organelles, as shown by the effect of deleting genes involved in vacuolar acidification. Organellar sequestration cannot account entirely for the Cl− accumulation, however, because the cell water:medium [Cl−] ratio in low Cl− medium is ∼10 at extracellular pH 4.0 even in vma1 yeast, which lack the vacuolar H+-ATPase. Cellular Cl− accumulation is ATP dependent in both wild type and vma1 strains. The initial 36Cl− influx is a saturable function of extracellular [36Cl−] with K1/2 of 0.02 mM at pH 4.0 and >0.2 mM at pH 7, indicating the presence of a high affinity Cl− transporter in the plasma membrane. The transporter can exchange 36Cl− for either Cl− or Br− far more rapidly than SO4 =, phosphate, formate, HCO3 −, or NO3 −. High affinity Cl− influx is not affected by deletion of any of several genes for possible Cl− transporters. The high affinity Cl− transporter is activated over a period of ∼45 min after shifting cells from high-Cl− to low-Cl− media. Deletion of ORF YHL008c (formate-nitrite transporter family) strongly reduces the rate of activation of the flux. Therefore, Yhl008cp may be part of a Cl−-sensing mechanism that activates the high affinity transporter in a low Cl− medium. This is the first example of a biological system that can regulate cellular Cl− at concentrations far below 1 mM.

Topology Optimization of a Reinforced Wing Box for Enhanced Roll Maneuvers

In this paper, the aileron reversal speed of a wing torsion box is maximized by reinforcing its upper skin. We propose a topology optimization approach using the spectral level set methodology. This is based on the level set methods,which represent theinterface describing thereinforcements asthe zerolevel setofafunction. Accordingto the proposed methodology, this function is discretized using its Fourier coefficients. These coefficients become the design variables of the optimization problem assigned to define the reinforcing layout. Results show that approximately the sameoptimal reinforcement layout isobtained from topologically different initialconfigurations. The two underlying ideas of the present work are to propose the spectral level set methodology as a framework for topology optimization, given its potential for reducing the design space dimension, and, considering the possibilities of new custom-made materials, to readdress the reinforcement perspective in aircraft structures without the weight penalty. Nomenclature ai,bi = problem domain boundaries corresponding to componenti ofx at = � t smoothness parameter aV = � V smoothness parameter a0 = lift curve slope bt = minimum thickness C = positive constant Cl� = derivative of the rolling moment coefficient of the rigid airplane with respect to� C �� � y;n� = twist aty produced by a unit moment at�

The effect of CO2 on the solubility of H2O-Cl fluids in andesitic melt

The solubility of C-O-H-Cl-bearing fluids in andesitic melt was investigated experimentally at temperatures of 1050 and 1200 °C and pressure of 200 MPa. The CO 2 -free andesitic melts produced experimentally contained up to 5.5–6 wt.% H 2 O and up to 2.5 wt.% Cl at the investigated conditions. The complex non-linear relationship between the concentrations of H 2 O and Cl in the melt indicates a strong non-ideality of the H 2 O-salt-bearing fluid phase(s), presumably resulting in the formation of two immiscible fluids. The addition of CO 2 to the system (80–800 ppm dissolved CO 2 in the melt) has two effects: a simple dilution of the fluid at low bulk Cl concentration and a significant influence on the mixing properties of the H 2 O- and Cl-bearing fluids related to the enlargement of the immiscibility gap in the fluid at higher bulk Cl content. The first effect results in lower H 2 O (by ∼ 1 wt.%) and almost constant Cl concentrations in the melt, while the second effect causes an increase in activity coefficients of both H2O and Cl. This effect of CO 2 is expected to be most pronounced at low pressures and high CO 2 concentrations in Cl-bearing mafic melts due to an enlargement of the immiscibility gap in fluids with decreasing pressure and an increase in proportions of divalent cations.

多雪山地流域の融雪期における河川水の水質形成過程

In a snowy watershed, the response of streamwater chemistry to snowmelt depends not only on meltwater chemistry but on the hydrochemical processes of the subsurface water. In this study, the δ18O values and solute concentrations of the precipitation, meltwater, subsurface water and surface water at the Moshiri experimental watershed located in the northern part of Hokkaido, Japan were obtained, and were discussed here in order to clarify the subsurface runoff processes and the formational mechanisms of the subsurface and surface water chemistry during the snowmelt season. A groundwater with a constant δ18O value (-12.3‰) and constant Cl- concentration (200 μeq/L) was widely found in the watershed and in the shallow saturated water zone. Hydrograph separations with high precision were conducted using δ18O early in the snowmelt season (Mar. 23-Apr. 14), and using a Cl- concentration during the active snowmelt season (Apr. 21-May 1). The contributions of the old water to the streamwater discharge were 82% (Mar. 23-Apr. 14) and 76% (Apr. 21-May 1). The contributions of old water were very high throughout the snowmelt season, which means that the groundwater reservoir must be significantly large. Subsequently, the temporal and spatial variations of the SiO2 concentrations of the subsurface water and surface water were observed to clarify the chemistry of the subsurface water, and revealed that there were two geographic sources (shallow groundwater and deep groundwater) in the ground. The SiO2 concentration of the deep groundwater was higher than that of the shallow groundwater. The sources of two spring waters changed from the deep groundwater to the shallow groundwater, and the SiO2 concentrations of these waters decreased while the discharges of these waters increased. The SiO2 concentration of old water was estimated using the results of isotopic and chloride hydrograph separation. Then, the result of the relationship between the amount of old water discharge and the SiO2 concentration of old water showed that the source of old water during the low outflow period was deep groundwater, and the source during the low outflow period was shallow groundwater. As the discharge of the old water reached over 0.08m3/s, the estimated SiO2 concentration of the old water became constant. These results indicated that a large amount of the old water flowing out to the river in the active snowmelt season was discharged from shallow groundwater. By observing the snowmelt runoff processes in a nival watershed, it was clarified that the old water is composed of a combination of two sources of groundwater and that the shallow groundwater chemistry greatly affects the streamwater chemistry during the large stormflow period.