Higher Fluid Research Articles

The relationship between fluid intelligence and sustained inattentional blindness in 7-to-14-year-old children.

Previous researches have shown that people with higher fluid intelligence are more likely to detect the unexpected stimuli. The current study systematically explored the relationship between fluid intelligence and sustained inattentional blindness in children. In Experiment 1, we measured one hundred and seventy-nine 7-to-14-year-old children's fluid intelligence and sustained inattentional blindness. The results showed that fluid intelligence was negatively related to sustained inattentional blindness only in 7-to-8-year-old children. In Experiment 2, we explored sustained inattentional blindness in sixty children with high Raven's scores. We found that compared with children who have average Raven's scores aged 11-to-12 years old, children with high Raven's scores were unable to better avoid sustained inattentional blindness. In general, this research implies that the relation between fluid intelligence and sustained inattentional blindness is weak. Fluid intelligence could predict sustained inattentional blindness only when children do not have enough perceptual capacities to complete the primary task.

Microvascular fluid exchange during CPB with deep hypothermia circulatory arrest or low flow.

Use of deep hypothermic low-flow (DHLF) cardiopulmonary bypass (CPB) has been associated with higher fluid loading than the use of deep hypothermia circulatory arrest (DHCA). We evaluated whether these perfusion strategies influenced fluid extravasation rates and edema generation differently per-operatively. Twelve anesthetized pigs, randomly allocated to DHLF (n = 6) or DHCA (n = 6), underwent 2.5 hours CPB with cooling to 20°C for 30 minutes (min), followed by 30 min arrested circulation (DHCA) or 30 min low-flow circulation (DHLF) before 90 min rewarming to normothermia. Perfusion of tissues, fluid requirements, plasma volumes, colloid osmotic pressures and total tissue water contents were recorded and fluid extravasation rates calculated. During the experiments, cerebral microdialysis was performed in both groups. Microvascular fluid homeostasis was similar in both groups, with no between-group differences, reflected by similar fluid extravasation rates, plasma colloid osmotic pressures and total tissue water contents. Although extravasation rates increased dramatically from 0.10 (0.11) ml/kg/min (mean with standard deviation in parentheses) and 0.16 (0.02) ml/kg/min to 1.28 (0.58) ml/kg/min and 1.06 (0.41) ml/kg/min (DHCA and DHLF, respectively) after the initiation of CPB, fluid filtrations during both cardiac arrest and low flow were modest and close to baseline values. Cerebral microdialysis indicated anaerobic metabolism and ischemic brain injury in the DHCA group. No differences in microvascular fluid exchange could be demonstrated as a direct effect of DHCA compared with DHLF. Thirty minutes of DHCA was associated with anaerobic cerebral metabolism and possible brain injury.

Adsorption of Alkanes in the Dense Vapor Phase on a Microporous Activated Carbon

Adsorption isotherms and enthalpies of adsorption of supercritical methane and n-propane, n-pentane, and n-heptane in the dense vapor phase were determined on a fully characterized microporous activated carbon (AC) over a wide range of temperature [303.15 (K)–443.15 (K)] and pressure [0.1–2 (MPa)]. These measurements were performed using a homemade manometric-calorimetry device (Mouahid et al. 20121). The most striking adsorption behaviors were encountered: (1) at low coverage zone, preferential adsorption of the n-alkanes is increasing with chain length; (2) at higher pressures and higher fluid densities, where the adsorbate–adsorbate are predominant, a linear regression was found between the adsorption enthalpies and the number chain segment. These original data obtained in a very broad experimental [P,T] range represent meaningful information which can be used for theoretical development.

The relation between positive fluid balance and the prognosis in severe sepsis patients with acute kidney injury

Objective To investigate the relation between positive fluid balance and the prognosis in severe sepsis patients with acute kidney injury (AKI). Methods A retrospective analysis of clinical data of 90 patients in our department was carried out. According to the final outcome, patients were divided into survival group (n=26) and non-survival group (n=64), in which the relation between patients’positive fluid balance and the prognosis was evaluated. Results (1)There was no statistically significant difference in the age and severity between survival group and non-survival group of patients with severe sepsis and consequent AKI, but the patients in non-survival group had greater volume overload. Compared with the survival group, higher mean fluid balance [(1 112.12±546.85) mLvs.(644.69±474.93)mL, P=0.00], and less urine output [(1 224.07±708.79)mL vs.(2 032.36±723.53)mL, P=0.00) in non-survival group.(2)There was no significant difference in mortality between early and late continuous renal replacement therapy (CRRT) during ICU care. However, the average daily fluid load in late CRRT patients was significantly greater than that in early CRRT patients [(1178.81±397.03)mLvs.(287.22±433.53)mL, P=0.00]and the lung oxygenation index in late CRRT patients was significantly worse than that in early CRRT patients [(211.22±42.56)vs.(169.46±57.40), P=0.04](3)The relevant variables to 28-day mortality in AKI patients with severe sepsis included CRRT treatment, oxygenation index and the average daily fluid balance>500 mL.Among them, fluid balance>500mL was an independent risk factor for AKI patients with severe sepsis. Their prognosis was worse if they had greater positive fluid balance. CRRT was the protective factor which could affect the prognosis of patients with severe sepsis complicated by AKI. Conclusions Patients with severe sepsis complicated by AKI has a high mortality. Persistent fluid overload can lead to increased mortality in patients with severe sepsis complicated by AKI. Early CRRT can reduce fluid retention in patients with renal failure and improve oxygenation index. Key words: Acute kidney injury; Severe sepsis; Positive fluid balance

A molecular dynamics simulation on the effect of different parameters on thermal resistance of graphene-argon interface

Molecular dynamics simulations of argon molecules confined between two parallel graphene sheets are carried out to investigate the parameters affecting heat transfer and thermal properties. These parameters include wall–fluid interaction strength, fluid density and wall temperature. For constant wall temperature simulations, we show that the first two parameters have influence on near-wall fluid density. As a result, the heat transfer at wall–fluid interfaces and thus through argon molecules across the domain will change. Also, we demonstrate that variations in wall temperature rarely affects the density profiles of argon molecules next to the walls. Therefore, in these cases, the variations in thermal resistance at the interface is most dominantly due to wall temperature itself. To analyse the results, the density and temperature profiles and also other parameters including heat flux and temperature gradient of bulk of argon molecules, Kapitza length and argon thermal conductivity are considered. The Kapitza length describes thermal resistance at liquid–solid interface. According to the results, increasing wall–fluid interaction strength leads to greater molecular aggregation of argon molecules near the walls and, consequently, decreasing the Kapitza length. Furthermore, higher fluid density leads to greater thermal resistance at wall–fluid interactions and therefore greater temperature jumps are observed in temperature profiles.

Long-term coupled behaviour of cemented paste backfill in load cell experiments

ABSTRACTA pressure cell apparatus has been developed in this research work to study the long-term hydro-mechanical behaviour of cemented paste backfill (CPB) cured under applied stress. The samples are cured for 7, 28, 90 and 150 days and the evolution of their mechanical, hydraulic, physical and microstructural properties is studied. Also, the suction, temperature and electrical conductivity are monitored for a period of 150 days of curing. The testing and monitoring programmes are conducted in undrained conditions, with and without pressure application. The obtained results show that the curing stress affects the hydro-mechanical behaviour of CPB for up to 28 days. Within this curing period, the CPB exhibits enhanced hydro-mechanical performance. However, application of sustained excessive curing stress onto the CPB samples induces the propagation of microcracks in the backfill structure, thus causing lower mechanical strength and higher fluid permeability at the more advanced ages. Furthermore, the mineralogical and chemical compositions of the tailings (e.g., sulfidic tailings) can significantly alter the mechanical strength properties (uniaxial compressive strength and elastic modulus) and the permeability of the CPB. The evolution of coupled factors and characteristics of the CPB at an early age control and influence its long-term behaviour and performance.

Influence of Bacterial Detachment on the Bioflotation of Malachite

The effects of the bacterial growth phase on the malachite flotation were investigated in a well-controlled Hallimond tube system. Rhodococcus opacus, which is one of representative hydrophobic bacteria, was employed for this study. The test results showed that the bacteria in the stationary phase exhibit two-fold greater floatability than those in mid-exponential phase. To understand the observed flotation behavior, complementary cell characterization tests (e.g., zeta potential and contact angle measurements) and cell attachment tests were conducted. Interestingly, the bacteria at both phases exhibited similar surface properties as well as almost identical amount of cells attached onto the malachite, suggesting that the growth phase dependent flotation behavior cannot be attributed to the variation of cell surface properties and the extent of cell adsorption. On the other hand, cell detachment tests revealed that the amount of cells detached from the malachite surface is greater for the mid-exponential phase than the stationary phase due to the higher fluid drag applied to the cells at the mid-exponential phase, which was explained by the differences in the size and shape of attached bacteria onto the malachite surface. Specifically, the bacteria in the mid-exponential phase had a larger size and formed loosely-packed structures like an end-to end on the malachite surface. These morphological characteristics were found to cause the bacteria of mid-exponential phase to be separated highly sensitive and easy from malachite surface due to the fluid flow. The findings from this study suggest that in the case of bioflotation using a relatively large bacteria size than the collector, it is important to consider the cell detachment by the fluid flow that occurs during a flotation process.

Induced flow field of randomly moving nanoparticles: a statistical perspective

Thermal transport in nanofluids, i.e., suspensions of nanoparticles in a base fluid, is a subject of dispute in the literature with no conclusion as to the governing mechanisms describing it. The interaction between the suspended particles and the base fluid has been cited as the main contributor to the phenomenon. However, the exact cause of the enhancement of heat transfer in nanofluids is still not fully understood. In this study, a simplified computational approach for a nanofluid simulation is proposed. The fluid motions induced by the random Brownian motions of suspended particles are examined from a statistical perspective. The results confirm that the motions of the suspended particles induce a random flow field within the fluid and provide a statistical assessment of this field. As the Brownian time-step is reduced, the statistics of the fluid phase slowly converge. The statistics also indicate the existence of local convective eddies throughout the fluid phase as particles move about. Parameters related to the computational setup do not affect the statistics of the induced fluid velocity. However, implementation of the slip assumption affects the results of the simulation. The calculated local fluid disturbance varies with the particle size with the location of maximum depending on the slip assumption. Finally, it was observed that higher fluid temperature will have a stronger effect on the induced flow field.

Riftogenesis attractor structures in the lithosphere of the Baikal Rift System: Nature and formation mechanism

The results of fluid regime and seismic source studysuggest that the formation and arrangement of the riftogenesis attractor structures (RAS) in the lithosphereof the Baikal Rift System (BRS) are caused by thedynamics and energy release of the fluid systems. Themechanism of RAS formation and functioning arebased on the processes of selforganization in fluidizedmelts and rocks at different decompression regimes.The absolute majority of fluid systems of the lithosphere are open dissipative ones with selforganizationprocesses typical for them; the degree of manifestationof these selforganization processes depends on theenergy state of the system and the position relative tothe equilibrium state [1]. The lithosphere was selforganized on a global level in the Early Archaean,when the energy potential of dissipation was maximaland degassing was of an areal character. As the energypotential of fluid transfer decreased, the style of allendogenous processes changed from areal to belt andlinear at the boundary between the Archaean and Proterozoic. Later on, processes of lithosphere fluidization were located along linear zones of energy dissipation (deep faults). The deeper mantle levels werereached by a fault, the higher the solvent ability andenergy capacity of a fluid were, the stronger the selforganization of matter in the fault was. As a result,hightemperature massdemanding deep fluid systemsformed and then melting sources, zones of regionalmetasomatosis, and autonomous orebearing fluidsystems were organized on their basis in the upperlithosphere.The role played by deep fluids in the formation ofregional tectonic structures is exceptionally great, soany tectonic zone of higher fluid conductivitybecomes a selforganizing system in the future. Notethat the role played by tectonic factor is obviouslydeterminative at the first stage, but fluid systemsbecome so at the following stages. It is fluid systemsthat are forces breaking and restructuring the lithosphere after the influence of the tectonic factor finished. For the structures of this kind, three evolutionstages are distinguished: (1) disturbance of stationarity, (2) growth of the system’s energy potential withenergy absorption and the system’s selforganization,and (3) reduction of the energy potential and fade outof the system as an active fluidconductor. Analysis ofthe global geochronological data on the “lifetime” offluidized zones in the lithosphere indicates that theselonglived systems evolve under an oscillating regime.In the hierarchy of natural systems, intracontinental rift systems, consisting of deep fault zones andzones functioning in a relatively narrow thermodynamical regime, are classified as mesosystems [2]. It isknown that processes of different kinds run in openstationary systems, but the average parameters of theseprocesses do not change in any chosen time interval,while they vary in different parts of the system [3].These systems that change in space and time are identified as dynamic ones [4], and it follows from the theory that dissipative dynamic systems in geological–geophysical media must have spatiotemporal attractors, which are classified as riftogenesis attractors interms of the lithosphere of the rift zone; riftogenesisattractors are the zones in the medium and time periods, where and when earthquakes with normal faultingmechanisms dominate. Based on the data on earthquake source parameters in the BRS lithosphere, threeRASs are distinguished (Fig. 1) [5], and the timeattractors reflect the “assembling” structure in termsof an evolutionary scenario with bifurcation of tripleequilibrium [6]. In accordance with the actualismprinciple, RASs are considered as attributes of theBRS Cenozoic dynamics [7], and the three stages ofvolcanic activation are explained by consecutive origination and development of the three RASs: firstly inthe South Baikal Basin (Late Cretaceous–Paleocene),then in the Khubsugul Basin (Eocene–Oligocene),and finally in the Muya Basin (postOligocene). Two“rifting” stages [8], growing rates of rift processes, andpropagation of riftogenesis in the southwest andnortheast directions from the South Baikal Basin arerelated to the appearance and twoway evolution of the

Assessment of circulating blood volume with fluid administration targeting euvolemia or hypervolemia.

The occurrence of hypovolemia in the setting of cerebral vasospasm reportedly increases the risk for delayed ischemic neurologic deficits. Few studies have objectively assessed blood volume (BV) in response to fluid administration targeting normovolemia (NV) or hypervolemia (HV) and none have done so with crystalloids alone. The primary purpose was to evaluate the BV of patients with SAH receiving crystalloid fluid administration targeting NV or HV. The University of Washington IRB approved the study. Prospectively collected data was obtained from patients enrolled in a clinical trial and a concurrent group of patients who received IV fluids during the ICU stay. We defined a normovolemia (NV) and hypervolemia (HV) group based on the cumulative amount of IV fluid administered in mL/kg from ICU admission to day 5; ≥30-60mL/kg/day (NV) and ≥60mL/kg/day (HV), respectively. In a subgroup of patients, BV was measured on day 5 post ictus using iodinated (131)I-labeled albumin injection and the BVA-100 (Daxor Corp, New York, NY). Differences between the NV and HV groups were compared using Student's t-test with assumption for unequal variance. Twenty patients in the NV and 19 in the HV groups were included. The HV group received more fluid and had a higher fluid balance than the NV group. The subgroup of patients in whom BV was measured on day 5 (n=19) was not different from the remainder of the cohort with respect to the total amount of administered fluid and net cumulative fluid balance by day 5. BV was not different between the two groups and varied widely. Routinely targeting prophylactic HV using crystalloids does not result in a higher circulating BV compared to targeting NV, but the possibility of clinically unrecognized hypovolemia remains.

Evaluation of the sealing ability of pulp capping agents against leakage on direct pulp capping with a computerized fluid filtration meter

Objective: The aim of this study was to assess the sealing abilities of two calcium hydroxide (Ca[OH] 2) pastes and two mineral trioxide aggregates (MTA) against leakage on direct pulp capping with a computerized fluid filtration (CFF) method. Materials and Methods: The 60 recently extracted sound human molar teeth were sectioned at the level of the highest pulp horn to obtain dentin discs of 0.5 ± 0.2 mm. The dentin discs were numbered and permeability measurements were done before and after the operation for the same sample. For simulating direct pulp capping, dentin discs were perforated with a standard diamond bur and restorated with four different capping materials: Dycal, Calcimol light-curing (LC), ProRoot MTA and DiaRoot BioAggregate. Fluid movement measurements were tested with a CFF method and a mean value was calculated for each specimen. Results: Calcimol LC and Dycal showed significantly higher fluid conductance values compared to other pulp capping materials (P 0.05). Conclusion: Within the limitations of this study, it can be concluded that using the MTA materials as a pulp-capping agent would be more efficient than Ca (OH) 2 materials with regard to pulpal microleakage.

Development and Validation of Condensation Heat Exchanger Heat Transfer Model in TASS/SMR-S Code for the Integral Reactor SMART

SMART (system-integrated modular advanced reactor), which is a 330 MWt advanced integral nuclear power plant, was developed by the Korea Atomic Energy Institute (KAERI) for generating electricity and desalinating seawater. To enhance its safety, various design concepts were adopted, such as containing most of the reactor coolant system (RCS) components and a passive residual heat removal system (PRHRS). A thermal hydraulic evaluation and analysis of SMART is performed by TASS/SMR-S (transient and setpoint simulation/system-integrated modular reactor safety). The TASS/SMR-S code has various models reflecting the design features for SMART such as the core models (core power and core heat transfer models), the component model,s and the condensation heat exchanger (CHX) model. In this paper, the validation of the CHX model in the TASS/SMR-S code was performed with the POSTECH (Pohang University of Science & Technology) CHX test to evaluate the conservative prediction capability of the heat transfer coefficient on CHX. According to the calculation results, the TASS/SMR-S code calculates higher fluid temperature on the CHX tube outlet than the test data in all the cases. In addition, the coolant temperature for the coolant pool outlet and the local heat transfer coefficients in the two phase region are underpredicted compared with the test results. Involving heat removal for the RCS, it is possible to conservatively predict the TASS/SMR-S code compared with the test results.

Changes of the hemodynamics and extravascular lung water after different-volume fluid resuscitation in a piglet model of endotoxic shock

Practice recommendations have evolved, and consensus now exists among leading organizations such as the American College of Critical Care Medicine (ACCM) and Surviving Sepsis Campaign that fluid infusion is best initiated with boluses of 20 ml/kg, commonly requires 40-60 ml/kg but can be as much as 200 ml/kg if the liver is not enlarged and/or rales are not heard. The present study aimed to investigate and compare the changes of the hemodynamics and extravascular lung water after higher volume fluid resuscitation in a piglet model of endotoxic shock. Twenty piglets were used for establishing animal models of endotoxic shock by intravenous infusing lipopolysaccharide (LPS). The experimental animals were divided into three groups according to the volume infused during the resuscitation. The three groups received different volume of saline in less than an hour after endotoxic shock. By the PiCCO plus system, we investigated the changes of hemodynamics and extravascular lung water. After fluid resuscitation, global end diastolic volume inder, (GEDI) and intrathoracic blood volume index, (ITBI) markedly increased in the group of 80 ml/kg and 120 ml/kg, but there was no change in the group of 40 ml/kg. GEDI: Fifteen min after fluid resuscitation R1 was (261 ± 64) ml/m(2), R2 (457 ± 124) ml/m(2), R3 (413 ± 148) ml/m(2), 4 h R1 (251 ± 68) ml/m(2), R2 (422 ± 70) ml/m(2), R3 (470 ± 160) ml/m(2); ITBI: Fifteen min after fluid resuscitation R1 was (335 ± 69) ml/m(2), R2 (550 ± 179) ml/m(2), R3 (520 ± 183) ml/m(2), 4 h R1 (314 ± 84) ml/m(2), R2 (534 ± 96) ml/m(2), R3 (594 ± 200) ml/m(2) (R1 vs. R2 vs. R3, F = 26.373, P < 0.05; R1 vs. R2, R1 vs. R3, P < 0.05; R2 vs. R3, P > 0.05). CI of all three groups significantly decreased when the models were established. After fluid resuscitation, the base level was maintained in the group of 80 ml/kg and 120 ml/kg, but it was under the basic level in the group of 40 ml/kg.Fifteen min after fluid resuscitation R1 was (4.5 ± 0.7) L/(min·m(2)), R2 (6.4 ± 2.2) L/(min·m(2)), R3 (5.5 ± 0.7) L/(min·m(2)), 4 h R1 (4.1 ± 1.0) L/(min·m(2)), R2 (5.2 ± 0.9) L/(min·m(2)), R3 (5.1 ± 0.8) L/(min·m(2)). There was no significant difference in CI between these two groups (P > 0.05).ELWI of the group of 80 ml/kg and 120 ml/kg were still higher than that of the group of 40 ml/kg, 15 min after fluid resuscitation R1 was (19.2 ± 8.6) ml/kg, R2 (29.2 ± 5.5) ml/kg, R3 (23.4 ± 8.2) ml/kg, 4 h R1 (18.3 ± 6.5) ml/kg, R2 (23.8 ± 2.6) ml/kg, R3 (21.4 ± 3.9) ml/kg, but there was no significant difference in ELWI among the groups (P > 0.05). Resuscitation with higher volume of fluid infusion in the early stage of endotoxic shock was more efficient to increase the preload and maintain the cardiac output at the baseline level, and might reduce the need for vasoactive agents. Meanwhile, resuscitation with higher volume of fluid in the early stage of endotoxic shock did not sharply increase the extravascular lung water.

Experimental Study of Fouling Resistance in Twisted Tube Heat Exchanger

This paper discusses fouling of a twisted tube heat exchanger under different conditions of fluid velocity and heat input. The fluid velocity was varied from 0.5 to 2.0 m/s, whereas the heat input to the heat exchanger was varied from 200 to 800 W. The experimental results show that for low fluid velocity of 0.5 m/s, the fouling resistance showed noticeable variation with respect to heat input, whereas for high velocity ranges, that is, 1.0–2 m/s, the variation in fouling resistance is less. The fouling in twisted tube steadily increases with time for different values of heat input from 1000 min onward for fluid velocity in the range from 1.0 to 2.0 m/s. It is also observed that fouling resistance curves overlap for various values of heat input. During the initial 1000 min of the test duration, the maximum fouling in a twisted tube heat exchanger decreases with increase in fluid velocity from 1.0 to 2.0 m/s. This behavior of the fouling rate can be attributed to the fact that at higher fluid velocity, flow becomes turbulent, and this in turn flushes the fouling particles. The time-series correlations for the fouling resistance are found to be logarithmic in nature.

Effects of Restricted Fructose Access on Body Weight and Blood Pressure Circadian Rhythms

High-fructose diet is known to produce cardiovascular and metabolic pathologies. The objective was to determine whether the timing of high fructose (10% liquid solution) intake affect the metabolic and cardiovascular outcomes. Male C57BL mice with radiotelemetric probes were divided into four groups: (1) 24 h water (control); (2) 24 h fructose (F24); (3) 12 h fructose during the light phase (F12L); (4) 12 h fructose during the dark phase (F12D). All fructose groups had higher fluid intake. Body weight was increased in mice on restricted access with no difference in total caloric intake. Fasting glycemia was higher in groups with restricted access. F24 mice showed a fructose-induced blood pressure increase during the dark period. Blood pressure circadian rhythms were absent in F12L mice. Results suggest that the timing of fructose intake is an important variable in the etiology of cardiovascular and metabolic pathologies produced by high fructose consumption.

Chemical microenvironments within sulfide structures from the Mothra Hydrothermal Field: Evidence from high-resolution zoning of trace elements

Massive portions of a ~ 300 °C black smoker (Finn) and a diffusely venting, intermediate temperature (~ 200 °C) chimney (Roane) recovered from the Mothra Hydrothermal Field on the Juan de Fuca Ridge have been analyzed in detail for bulk chemistry. The size of the recovered pieces of chimney enabled physical segregation and analysis of distinct chemical zonation within the structures. In particular, large variations in the concentrations of minor and trace elements in the different mineralogical zones provide new insight into the processes involved in chimney growth that are not evident from the bulk mineralogy. Systematic zonation of trace and minor elements is strongly influenced by redox conditions, multiple host phases, single or dual fluid source, and the mixing–cooling history of the fluids, even within an individual mineralogical zone. Distinct chemical microenvironments within the chimneys are recognized that provide a basis for detailed reconstruction of the changing conditions in the interiors of the chimneys during their growth. In Finn, 14 discrete chemical microenvironments are recognized in 80 of 90 samples based on high resolution zoning of major and trace elements. Four of the microenvironments are Cu-rich, three are Zn-rich, one is Fe-rich with low Cu, two are Ca-rich, three are SiO 2-rich, and one is Ba and SiO 2-rich. In Roane, 24 discrete chemical microenvironments are recognized. Six of the microenvironments are SiO 2-poor (< 1 wt.%) with low SO 4, two have low SiO 2 (1–10 wt.%) and low SO 4, four have low SiO 2 and are SO 4-free, four have moderate SiO 2, three are SiO 2-rich, four have low to moderate Ba, and one is Ba-rich. The trace elements Se, Co, In, and Te do not display their typical simple associations with high concentrations of Cu. Variable Se concentrations in the most Cu-rich samples likely reflect variable Se/S ratios of the hydrothermal fluids in response to changing pH, oxidation state or mixing. Co and Te are strongly partitioned into pyrite instead of chalcopyrite indicated by concentrations of these elements remaining high even as the Cu content decreases. Indium also may be present either in chalcopyrite or in Zn sulfides ± chalcopyrite disease. In Roane, an unexpected correlation between Zn, Cd, Cu and Se is thought to reflect buffering of the fluids to a high pH by ammonia, which increases the saturation temperature of Zn sulfides and caused codeposition of Cu and Zn, with Cd enriched in Zn sulfides and Se enriched in Cu sulfides. The notable Ag enrichment in the Cu-rich samples from Finn are distinct from East Pacific Rise black smokers, possibly due to the lower temperatures (~ 300 °C vs. ≥ 350 °C) and higher fluid pH. Lower temperature assemblages in both Finn and Roane are enriched in Sb, Tl, Hg, Pb, ± Au, and ± Ag. Arsenic is enriched in some low-temperature zones but is most strongly correlated with Mo in pyrite; both elements are also absorbed from seawater as oxyanions. Uranium and V are also interpreted to have a seawater source and both may be present in clay minerals, together with the alkalies (Na, K, Rb, and Cs) while U may also be associated with sulfate minerals. Variable enrichments of Al 2O 3, U, and V in the silica-rich microenvironments within Finn and Roane indicate either seawater–hydrothermal fluid mixing or conductive cooling of hydrothermal fluid as the main process precipitating the silica. These findings have implications for the range of possible microbial habitats that may develop within chimney structures during their growth, which may include highly variable redox gradients and the availability of different nutrients.

Seasonal dynamics of three inquiline species in isolated island populations of Sarracenia purpurea L. in Lake Michigan

AbstractA seasonal survey of the abundances of three inquilines species in Sarracenia purpurea L. leaves was conducted by sampling 240 leaves from three pitcher plant populations on Beaver Island in Lake Michigan, United States. Leaf characteristics such as fluid pH, fluid volume, and keel length were quantified. The study focused primarily on the larvae of three dipteran inquiline species – the midge, Metriocnemus knabi Coquillet, the mosquito, Wyeomyia smithii (Coquillet), and the flesh fly, Fletcherimyia fletcheri Aldrich. Dipteran inquiline abundances varied with sampling season. Most pitchers contained one of the three studied inquilines species. Mosquito abundances were low relative to the other inquilines. In samples collected soon after new leaves open, a mixture of mosquito and midge larvae was characteristic. We related inquilines abundances to leaf parameters using generalized linear mixed models. The midge and mosquito responded differently to leaf parameters during different sampling seasons, where as the flesh fly showed no response. The most important leaf parameters were pH and percent of total leaf volume filled with fluid (relative volume). The midge and mosquito were more likely to be present in pitchers with low pH and higher fluid volume. Our results indicate that pitchers of isolated northern populations of S. purpurea are inhabited by a less diverse insect community than reported elsewhere. Our study also suggests that site isolation may play an important role in the seasonal variation of inquiline community structure.

Analytical and experimental investigation of grinding fluid hydrodynamic pressure at wedge-shaped zone

The conventional method of delivering grinding fluid with a high supply of pressure and hydrodynamic fluid pressure can be generated ahead of the contact zone due to the wedge effect. In the present paper, theoretical hydrodynamic pressure modelling was applied to induce a flow of coolant fluid through the grinding zone during flood delivery grinding. The simulation results show that hydrodynamic pressure was proportional to grinding wheel velocity, and inversely proportional to the minimum gap between the wheel and workpiece surface. The maximum pressure value was generated in the minimum gap region where higher fluid pressure gradient occurred. Moreover, the hydrodynamic pressure at the wedge-shaped zone was also measured through experiments. The results suggest that the proposed model agrees with the theoretical model and it can accurately forecast changes in the hydrodynamic pressure at the contact zone between the grinding wheel and the workpiece.

An Investigation Hydrodynamic Fluid Pressure at Wedge-Shaped Gap between Grinding Wheel and Workpiece

In the grinding process, conventional method of flood delivering coolant fluid by a nozzle in order to achieve good surface integrity. However, hydrodynamic fluid pressure can be generated ahead of the contact zone due to the wedge effect between wheel peripheral surface and work surface. In the paper, a theoretical hydrodynamic pressure modeling is presented for flow of coolant fluid through the grinding zone in flood delivery grinding. Moreover, coolant induced force can be calculated by integrate the hydrodynamic pressure distribution over the whole contact length. The theoretical results show that the hydrodynamic pressure was proportion to grinding wheel velocity, and inverse proportion to the minimum gap between wheel and work surface and the maximum pressure value was generated just in the minimum gap region in which higher fluid pressure gradient occuring. It can also be concluded the pressure distribution was uniform in the direction of width of wheel except at the edge of wheel because of the side-leakage.

Technology Focus: Drilling and Completion Fluids (November 2010)

Technology Focus Last year, I wrote about the science-based approach to fluids and the increased level of knowledge required of drilling-fluids-related professionals. This year, I want to emphasize the importance of drilling and completion fluids in well control, lost-circulation mitigation, and wellbore stability. One of the first things you learn as a drilling engineer or rig supervisor is that the most important aspect in drilling is the drilling fluid (this may be a little biased coming from a fluids specialist). It is like the blood in our circulatory system! It serves many functions and can be either friend or foe, depending upon how it is maintained. The primary function of drilling or completion fluids is to control subsurface pressures. With the challenge of drilling in ever-increasing water depths and into higher-pressure and temperature reservoirs in the pursuit of hydrocarbons, this becomes even more important and more difficult to accomplish. Additionally, the fluid density required to control formation pressures often is very close to the fracture gradient, so that there is a delicate balance between well control and lost returns. Another issue to consider is the effect that fluids have on wellbore stability. With the increased complexity of the wells being drilled, higher fluid densities are needed to prevent the hole from becoming mechanically unstable, thus narrowing the “safe drilling window” between borehole stability and lost returns. Various techniques are used to address this issue. Factors such as formation type and characteristics, type of loss, and others should be considered when selecting the most appropriate solution. There is no “one size fits all” approach that works. The papers in this feature address issues in the preceding discussion. Please take time to read them along with the papers listed for additional reading. Drilling and Completion Fluids additional reading available at OnePetro: www.onepetro.org SPE 130413 • “Vital Role of Nanopolymers in Drilling- and Stimulation-Fluid Applications” by Subodh Singh, University of Oklahoma, et al. SPE 125708 • “Remote Real-Time Monitoring of Particle-Size Distribution in Drilling Fluids During Drilling of a Depleted HP/HT Reservoir” by Egil Ronaes, SPE, M-I Swaco, et al. SPE 130421 • “Utility-Calculation Method of New Four-Parameter Rheological Model for Drilling Hydraulics” by Guo Wang, China University of Petroleum, Beijing, et al. SPE 128405 • “Salinity-Based Pump-and-Dump Strategy for Drilling Salt With Supersaturated Fluids” by T.J. Akers, SPE, ExxonMobil