Heterogeneous porous media: Fronts and noise

NASA Astrophysics Data System (ADS)

Chaouchel, M.; Rakotomalala, N.; Salin, D.; Xu, B.; Yortsos, Y. C.

Capillary effects can be important in immiscible flows in heterogeneous media, particularly at low capillary numbers (Ca). We present experiments and simulations of slow drainage in 3-D porous media, either homogeneous and in the presence of buoyancy or heterogeneous and in its absence. An acoustic technique allows for an accurate study of the 3-D fronts and the cross-over region. Our results suggest that both cases can be described by invasion percolation in a gradient. Both front tails scale with the corresponding Bond numbers as σft≈B-47 in agreement with the theory. An analogous scaling for viscous effects is also given. The noise of these fronts are found correlated in the form of a fractional Brownian motion (fBm) of a Hurst exponent H≈.5. At higher Ca, experiments performed in 3-D porous media with sharp changes in permeability, exhibit a saturation profile response closely linked to the permeability variations. This viscous response to heterogeneity provides an opportunity to investigate and determine correlated (even at all scales, i.e. fBm), permeability fields.

Dynamics of liquid spreading on solid surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kalliadasis, S.; Chang, H.C.

1996-09-01

Using simple scaling arguments and a precursor film model, the authors show that the appropriate macroscopic contact angle {theta} during the slow spreading of a completely or partially wetting liquid under conditions of viscous flow and small slopes should be described by tan {theta} = [tan{sup 3} {theta}{sub e} {minus} 9 log {eta}Ca]{sup 1/3} where {theta}{sub e} is the static contact angle, Ca is the capillary number, and {eta} is a scaled Hamaker constant. Using this simple relation as a boundary condition, the authors are able to quantitatively model, without any empirical parameter, the spreading dynamics of several classical spreadingmore » phenomena (capillary rise, sessile, and pendant drop spreading) by simply equating the slope of the leading order static bulk region to the dynamic contact angle boundary condition without performing a matched asymptotic analysis for each case independently as is usually done in the literature.« less

Dynamic pore-scale network model (PNM) of water imbibition in porous media

NASA Astrophysics Data System (ADS)

Li, J.; McDougall, S. R.; Sorbie, K. S.

2017-09-01

A dynamic pore-scale network model is presented which simulates 2-phase oil/water displacement during water imbibition by explicitly modelling intra-pore dynamic bulk and film flows using a simple local model. A new dynamic switching parameter, λ, is proposed within this model which is able to simulate the competition between local capillary forces and viscous forces over a very wide range of flow conditions. This quantity (λ) determines the primary pore filling mechanism during imbibition; i.e. whether the dominant force is (i) piston-like displacement under viscous forces, (ii) film swelling/collapse and snap-off due to capillary forces, or (iii) some intermediate local combination of both mechanisms. A series of 2D dynamic pore network simulations is presented which shows that the λ-model can satisfactorily reproduce and explain different filling regimes of water imbibition over a wide range of capillary numbers (Ca) and viscosity ratios (M). These imbibition regimes are more complex than those presented under drainage by (Lenormand et al. (1983)), since they are determined by a wider group of control parameters. Our simulations show that there is a coupling between viscous and capillary forces that is much less important in drainage. The effects of viscosity ratio during imbibition are apparent even under conditions of very slow flow (low Ca)-displacements that would normally be expected to be completely capillary dominated. This occurs as a result of the wetting films having a much greater relative mobility in the higher M cases (e.g. M = 10) thus leading to a higher level of film swelling/snap-off, resulting in local oil cluster bypassing and trapping, and hence a poorer oil recovery. This deeper coupled viscous mechanism is the underlying reason why the microscopic displacement efficiency is lower for higher M cases in water imbibition processes. Additional results are presented from the dynamic model on the corresponding effluent fractional flows (fw) and global pressure drops (ΔP) as functions of capillary number and viscosity ratio. These results indicate that unsteady-state (USS) relatively permeabilities in imbibition should be inherently rate dependent.

Analysis of the boundary conditions for a Hele--Shaw bubble

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burgess, D.; Foster, M.R.

1990-07-01

Effective boundary conditions are derived to be used with the classical Hele--Shaw equations in calculating the shape and motion of a Hele--Shaw bubble. The main assumptions of this analysis are that the displaced fluid wets the plates, and that the capillary number Ca and the ratio of gap width to characteristic bubble length {epsilon} are both small. In a small region at the sides of the bubble, it is found that the thin-film thickness scales with {epsilon}{sup 2/5} Ca{sup 4/5}, rather than the Ca{sup 2/3} scaling that is valid over most of the thin film above and below the bubble.

Instability of long fingers in Hele--Shaw flows

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, C.W.; Homsy, G.M.

1985-06-01

Experiments on steady fingers and their stability in Hele--Shaw cells, are reported. It is shown that the shape of steady fingers scales with a modified capillary number, Ca', as suggested by McLean and Saffman (J. Fluid. Mech. 102, 455 (1981) and our previous analysis (J. Fluid Mech. 139, 291 (1984)). The behavior at large Ca' is investigated by using a wide Hele--Shaw cell. It is observed that such fingers are unstable for Ca'>100, in agreement with the prediction by Taylor and Saffman (second symposium on naval hydrodynamics, 1958, p. 277) of instability as Ca'..-->..infinity. The mechanism is identified as onemore » of tip-splitting, which occurs periodically in the weakly supercritical regime, and in a more complex fashion for large Ca'.« less

Multi-phase imaging of intermittency at steady state using differential imaging method by X-ray micro-tomography

NASA Astrophysics Data System (ADS)

Gao, Y.; Lin, Q.; Bijeljic, B.; Blunt, M. J.

2017-12-01

To observe intermittency in consolidated rock, we image a steady state flow of brine and decane in Bentheimer sandstone. We devise an experimental method based on X-ray differential imaging method to examine how changes in flow rate impact the pore-scale distribution of fluids during co-injection flow under dynamic flow conditions at steady state. This helps us elucidate the diverse flow regimes (connected, intermittent break-up, or continual break-up of the non-wetting phase pathways) for two capillary numbers. Also, relative permeability curves under both capillary and viscous limited conditions could be measured. We have performed imbibition sample floods using oil-brine and measured steady state relative permeability on a sandstone rock core in order to fully characterize the flow behaviour at low and high Ca. Two sets of experiments at high and low flow rates are provided to explore the time-evolution of the non-wetting phase clusters distribution under different flow conditions. The high flow rate is 0.5 mL/min, whose corresponding capillary number is 7.7×10-6. The low flow rate is 0.02 mL/min, whose capillary number is 3.1×10-7. A procedure based on using high-salinity brine as the contrast phase and applying differential imaging between the dry scan and that of the sample saturation with a 30 wt% Potassium iodide (KI) doped brine help to make sure there is no non-wetting phase in micro-pores. Then the intermittent phase in multiphase flow image at high Ca can be quantified by obtaining the differential image between the 30 wt% KI brine image and the scans that taken at each fixed fractional flow. By using the grey scale histogram distribution of the raw images at each condition, the oil proportion in the intermittent phase can be calculated. The pressure drops at each fractional flow at low and high Ca can be measured by high-precision pressure differential sensors and utilized to calculate to the relative permeability at pore scale. The relative permeability data and fw-Sw relationship obtained by our experiment at pore scale are compared with the data collected from experiments which were conducted at core scale, and they match well.

Lattice Boltzmann study of slip flow over structured surface with transverse slots

NASA Astrophysics Data System (ADS)

Chen, Wei; Wang, Kai; Wang, Lei; Hou, Guoxiang; Leng, Wenjun

2018-04-01

Slip flow over structured superhydrophobic surface with transverse slots is investigated by the lattice Boltzmann method. The Shan-Chen multiphase model is employed to simulate the flow over gas bubbles in the slots. The Carnahan-Starling equation of state is applied to obtain large density ratio. The interface thickness of the multiphase model is discussed. We find that the Cahn number Cn should be smaller than 0.02 when the temperature T = 0.5T c to restrict the influence of interface thickness on slip length. Influences of slot fraction on slip length is then studied, and the result is compared with single LB simulation of which the interface is treated as free-slip boundary. The slip length obtained by the multiphase model is a little smaller. After that, the shape of the liquid-gas interface is considered, and simulations with different initial protrusion angles and capillary numbers are performed. Effective slip length as a function of initial protrusion angle is obtained. The result is in qualitative agreement with a previous study and main features are reproduced. Furthermore, the influence of Capillary number Ca is studied. Larger Ca causes larger interface deformation and smaller slip length. But when the interface is concaving into the slot, this influence is less obvious.

Wettability impact on supercritical CO2 capillary trapping: Pore-scale visualization and quantification

NASA Astrophysics Data System (ADS)

Hu, Ran; Wan, Jiamin; Kim, Yongman; Tokunaga, Tetsu K.

2017-08-01

How the wettability of pore surfaces affects supercritical (sc) CO2 capillary trapping in geologic carbon sequestration (GCS) is not well understood, and available evidence appears inconsistent. Using a high-pressure micromodel-microscopy system with image analysis, we studied the impact of wettability on scCO2 capillary trapping during short-term brine flooding (80 s, 8-667 pore volumes). Experiments on brine displacing scCO2 were conducted at 8.5 MPa and 45°C in water-wet (static contact angle θ = 20° ± 8°) and intermediate-wet (θ = 94° ± 13°) homogeneous micromodels under four different flow rates (capillary number Ca ranging from 9 × 10-6 to 8 × 10-4) with a total of eight conditions (four replicates for each). Brine invasion processes were recorded and statistical analysis was performed for over 2000 images of scCO2 saturations, and scCO2 cluster characteristics. The trapped scCO2 saturation under intermediate-wet conditions is 15% higher than under water-wet conditions under the slowest flow rate (Ca ˜ 9 × 10-6). Based on the visualization and scCO2 cluster analysis, we show that the scCO2 trapping process in our micromodels is governed by bypass trapping that is enhanced by the larger contact angle. Smaller contact angles enhance cooperative pore filling and widen brine fingers (or channels), leading to smaller volumes of scCO2 being bypassed. Increased flow rates suppress this wettability effect.

Analytic theory for the selection of Saffman-Taylor fingers in the presence of thin film effects

NASA Technical Reports Server (NTRS)

Tanveer, S.

1989-01-01

An analytic theory is presented for the width selection of Saffman-Taylor fingers in the presence of thin film effect. In the limit of small capillary number Ca and small gap to width ratio epsilon, such that epsilon much less than Ca much less than 1, it is found that fingers with relative width lambda less than 1/2 are possible such that lambda squared (1-lambda)/(1-2 lambda) = k epsilon/Ca(sup 3/2), where the positive constant k depends on the branch of solution and equals 2.776 for the first branch. A fully nonlinear analysis is necessary in this problem even to obtain the correct scaling law. It is also shown how in principle, the selection rule for arbitrary Ca can be obtained.

Characterization of voids formed during liquid impregnation of nonwoven multifilament glass networks as related to composite processing

NASA Technical Reports Server (NTRS)

Mahale, Anant D.; Prudhomme, Robert K.; Rebenfeld, Ludwig

1993-01-01

A technique based on matching the refractive index of an invading liquid to that of a fiber mat was used to study entrapment of air ('voids') that occurs during forced in-plane radial flow into nonwoven multifilament glass networks. The usefulness of this technique is demonstrated in quantifying and mapping the air pockets. Experiments with a series of fluids with surface tensions varying from 28 x 10(exp -3) to 36 x 10(exp -3) N/m, viscosities from 45 x 10(exp -3) to 290 x 10(exp -3) Pa.s, and inlet flow rates from 0.15 x 10(exp -6) to 0.75 x 10(exp -6) m(exp 3)/s, showed that void content is a function of the capillary number characterizing the flow process. A critical value of capillary number, Ca = 2.5 x 10(exp -3), identifies a zone below which void content increases exponentially with decreasing capillary number. Above this critical value, negligible entrapment of voids is observed. Similar experiments carried out on surface treated nonwoven mats spanning a range of equilibrium contact angles from 20 deg to 78 deg showed that there is a critical contact angle above which negligible entrapment is observed. Below this value, there is no apparent effect of contact angle on the void fraction - capillary number relationship described earlier. Studies on the effect of filament wettability, and fluid velocity and viscosity on the size of the entrapment (voids) were also carried out. These indicate that larger sized entrapments which envelop more than one pore are favored by a low capillary number in comparison to smaller, pore level bubbles. Experiments were carried out on deformed mats - imposing high permeability spots at regular intervals on a background of low permeability. The effect of these spatial fluctuations in heterogeneity of the mat on entrapment is currently being studied.

Stereological Study on the Positive Effect of Running Exercise on the Capillaries in the Hippocampus in a Depression Model.

PubMed

Chen, Linmu; Zhou, Chunni; Tan, Chuanxue; Wang, Feifei; Gao, Yuan; Huang, Chunxia; Zhang, Yi; Jiang, Lin; Tang, Yong

2017-01-01

Running exercise is an effective method to improve depressive symptoms when combined with drugs. However, the underlying mechanisms are not fully clear. Cerebral blood flow perfusion in depressed patients is significantly lower in the hippocampus. Physical activity can achieve cerebrovascular benefits. The purpose of this study was to evaluate the impacts of running exercise on capillaries in the hippocampal CA1 and dentate gyrus (DG) regions. The chronic unpredictable stress (CUS) depression model was used in this study. CUS rats were given 4 weeks of running exercise from the fifth week to the eighth week (20 min every day from Monday to Friday each week). The sucrose consumption test was used to measure anhedonia. Furthermore, stereological methods were used to investigate the capillary changes among the control group, CUS/Standard group and CUS/Running group. Sucrose consumption significantly increased in the CUS/Running group. Running exercise has positive effects on the capillaries parameters in the hippocampal CA1 and DG regions, such as the total volume, total length and total surface area. These results demonstrated that capillaries are protected by running exercise in the hippocampal CA1 and DG might be one of the structural bases for the exercise-induced treatment of depression-like behavior. These results suggest that drugs and behavior influence capillaries and may be considered as a new means for depression treatment in the future.

Pore-level influence of micro-fracture parameters on visco-capillary behavior of two-phase displacements in porous media

NASA Astrophysics Data System (ADS)

Rokhforouz, M. R.; Akhlaghi Amiri, H. A.

2018-03-01

In this work, coupled Cahn-Hilliard phase field and Navier-Stokes equations were solved using finite element method to address the effects of micro-fracture and its characterizations on water-oil displacements in a heterogeneous porous medium. Sensitivity studies at a wide range of viscosity ratios (M) and capillary numbers (Ca), and the resultant log Ca-log M stability phase diagram, revealed that in both media, with/without fracture, the three regimes of viscous fingering, capillary fingering and stable displacement similarly occur. However, presence of the fracture caused water channeling phenomenon which resulted in reduction of the number of active fingers and hence the final oil recovery factor. At high Ca (especially in the stable regime, with log Ca ≥ -2.5 and log M ≥ 0), recovery factor for the fractured medium was relatively identical with the non-fractured one. At log M ≥ 0, the fracture was fully swept, but flow instabilities were observed inside the fracture at lower M values, especially for log Ca > -4.6. In the case of the fractured medium at log Ca = -4.6 and log M = 0 (capillary dominant flow), it is observed that the primary breakthrough took place by a finger progressed through the matrix, not those channeled through the fracture. Geometrical properties of the fracture, including length, aperture and orientation, highly affected both displacement profile and efficiency. The fracture length inversely influenced the oil recovery factor. It was observed that there is a critical fracture width (almost half of the medium average pore diameter) at which the recovery factor of the medium during displacement is minimum, compared to the media having thinner and thicker fractures. Minor channeling effect in the media with thinner fracture and larger fracture swept volume as well as high fracture/matrix cross flow in the media with thicker fracture were detected as the main cause of this non-monotonic behavior. In the models with thick fractures (with the thickness higher than the average pore diameter), considerable trapped oil volumes were observed inside the fracture at low M values. The fracture orientation had the most impressive effect on oil recovery compared to the other studied parameters; where the oil recovery factor incremented more than 20% as the fracture rotated 90° from flow direction. Due to the dominant effect of the channeling phenomenon, the change in the medium wettability from slightly oil-wet to slightly water-wet, did not considerably affect the displacement profile in the fractured medium. However, oil recovery factor increased as the medium became more water-wet. The fracture area was fully swept by the injected water in the oil-wet and neutral-wet media. However, flow instabilities were observed inside the fracture of the water-wet medium due to counter-current imbibition between fracture/matrix. Micro-scale mechanisms of pore doublet effect, interface coalesce, snap-off and reverse movements were captured during the studied unstable displacements.

Development of a Specific Impulse Balance for a Pulsed Capillary Discharge (Preprint)

DTIC Science & Technology

2008-06-13

thrust stand [rad/s] I. Introduction A capillary discharge based coaxial , electrothermal pulsed plasma thruster (PPT) is currently under...20-23 July 2008. 14. ABSTRACT A capillary discharge based pulsed plasma thruster is currently under development at the Air Force Research...Edwards AFB, CA 93524 A capillary discharge based pulsed plasma thruster is currently under development at the Air Force Research Laboratory. A

Optofluidic ring resonator sensor for sensitive label-free detection of breast cancer antigen CA15-3 in human serum

NASA Astrophysics Data System (ADS)

Zhu, Hongying; Dale, Paul S.; Fan, Xudong

2009-05-01

Breast cancer is the most frequently diagnosed malignancy in women worldwide. Because of its great impact on society, a lot of research funding has been used to develop novel detection tools for aiding breast cancer diagnosis and prognosis. In this work, we demonstrated a simple, fast, and sensitive detection of circulating breast cancer biomarker CA15-3 with opto-fluidic ring resonator (OFRR) sensors. The OFRR sensor employs a thin-walled capillary with wall thickness less than 4 μm. The circular cross section of the capillary forms the optical ring resonator, in which the light circulates in the form of whispering gallery modes (WGMs). The capillary wall is thin enough that the evanescent field of the WGM extends into the capillary core and responds to refractive index changes in the capillary core or close to its interior surface. The WGM spectral position will change when the biomolecules bind to the surface, yielding quantitative and kinetic information about the biomolecule interaction. Here, the direct immunoassay method was employed for the detection of CA15-3 antigen without any signal amplification steps. The sensor performance in both PBS buffer and human serum were investigated, respectively. The experimental detection limit was 5 units/mL in PBS buffer and 30 units/mL for CA15-3 spiked in serum, both of which satisfied clinical diagnosis requirements. The potential use of the OFRR as the point-of-care device for breast cancer detection was tested by measuring the CA15-3 level in blood samples collected from stage IV breast cancer patients and the results were compared with standard clinical test.

Crossover from capillary fingering to viscous fingering in a rough fracture

NASA Astrophysics Data System (ADS)

Hu, R.; Chen, Y.; Wu, D. S.

2017-12-01

Controlled by the competition between capillary and viscous forces, the displacement patterns of one fluid displacing another more viscous one exhibit capillary fingering, viscous fingering, and the crossover between the two. Although extensive studies have investigated viscous and capillary fingerings in porous and fractured media, a few studies focused on the crossover in rough fractures, and how viscous and capillary forces affect the crossover remains unclear. Using a transparent fracture visualization system, we studied how the competition impacts the crossover in a horizontal rough fracture. Drainage experiments of water displacing oil were conducted at seven flow rates (capillary number log10Ca ranging from -7.07 to -3.07) and four viscosity ratios (M = 1/1000, 1/500, 1/100 and 1/50). We consistently observed lower invading fluid saturations in the crossover zone. In addition, we proposed a phase diagram for the displacement patterns in a rough fracture that is consistent with similar studies in porous media. Based on real-time imaging and statistical analysis of the invasion morphology, we showed that the competition between the capillary and viscous forces is responsible for the saturation reduction in the crossover zone. In this zone, finger propagation toward the outlet (characteristic of viscous fingering) as well as void-filling in the transverse and backward directions (characteristic of capillary fingering), are both suppressed. Therefore, the invading fluid tends to occupy larger apertures with higher characteristic front velocity, promoting void-filling toward the outlet with thinner finger growth and resulting in a larger volume of defending fluid left behind.

Multiplex ligation-dependent probe amplification analysis on capillary electrophoresis instruments for a rapid gene copy number study.

PubMed

Jankowski, Stéphane; Currie-Fraser, Erica; Xu, Licen; Coffa, Jordy

2008-09-01

Annotated DNA samples that had been previously analyzed were tested using multiplex ligation-dependent probe amplification (MLPA) assays containing probes targeting BRCA1, BRCA2, and MMR (MLH1/MSH2 genes) and the 9p21 chromosomal region. MLPA polymerase chain reaction products were separated on a capillary electrophoresis platform, and the data were analyzed using GeneMapper v4.0 software (Applied Biosystems, Foster City, CA). After signal normalization, loci regions that had undergone deletions or duplications were identified using the GeneMapper Report Manager and verified using the DyeScale functionality. The results highlight an easy-to-use, optimal sample preparation and analysis workflow that can be used for both small- and large-scale studies.

Dynamics of the liquid film around elongated bubbles rising in vertical capillaries

NASA Astrophysics Data System (ADS)

Magnini, Mirco; Khodaparast, Sepideh; Matar, Omar K.; Stone, Howard A.; Thome, John R.

2017-11-01

We performed a theoretical, numerical and experimental study on elongated bubbles rising in vertical tubes in co-current liquid flows. The flow conditions were characterized by capillary, Reynolds and Bond numbers within the range of Ca = 0.005 - 0.1 , Re = 1 - 2000 and Bo = 0 - 20 . Direct numerical simulations of the two-phase flows are run with a self-improved version of OpenFOAM, implementing a coupled Level Set and Volume of Fluid method. A theoretical model based on an extension of the traditional Bretherton theory, accounting for inertia and the gravity force, is developed to obtain predictions of the profiles of the front and rear menisci of the bubble, liquid film thickness and bubble velocity. Different from the traditional theory for bubbles rising in a stagnant liquid, the gravity force impacts the flow already when Bo < 4 . Gravity effects speed up the bubble compared to the Bo = 0 case, making the liquid film thicker and reducing the amplitude of the undulation on the surface of the bubble near its tail. Gravity effects are more apparent in the visco-capillary regime, i.e. when the Reynolds number is below 1.

Red Blood Cell Passage of Small Capillaries Is Associated with Transient Ca2+-mediated Adaptations.

PubMed

Danielczok, Jens G; Terriac, Emmanuel; Hertz, Laura; Petkova-Kirova, Polina; Lautenschläger, Franziska; Laschke, Matthias W; Kaestner, Lars

2017-01-01

When red blood cells (RBCs) pass constrictions or small capillaries they need to pass apertures falling well below their own cross section size. We used different means of mechanical stimulations (hypoosmotic swelling, local mechanical stimulation, passing through microfluidic constrictions) to observe cellular responses of human RBCs in terms of intracellular Ca 2+ -signaling by confocal microscopy of Fluo-4 loaded RBCs. We were able to confirm our in vitro results in a mouse dorsal skinfold chamber model showing a transiently increased intracellular Ca 2+ when RBCs were passing through small capillaries in vivo . Furthermore, we performed the above-mentioned in vitro experiments as well as measurements of RBCs filterability under various pharmacological manipulations (GsMTx-4, TRAM-34) to explore the molecular mechanism of the Ca 2+ -signaling. Based on these experiments we conclude that mechanical stimulation of RBCs activates mechano-sensitive channels most likely Piezo1. This channel activity allows Ca 2+ to enter the cell, leading to a transient activation of the Gardos-channel associated with K + , Cl - , and water loss, i.e., with a transient volume adaptation facilitating the passage of the RBCs through the constriction.

Red Blood Cell Passage of Small Capillaries Is Associated with Transient Ca2+-mediated Adaptations

PubMed Central

Danielczok, Jens G.; Terriac, Emmanuel; Hertz, Laura; Petkova-Kirova, Polina; Lautenschläger, Franziska; Laschke, Matthias W.; Kaestner, Lars

2017-01-01

When red blood cells (RBCs) pass constrictions or small capillaries they need to pass apertures falling well below their own cross section size. We used different means of mechanical stimulations (hypoosmotic swelling, local mechanical stimulation, passing through microfluidic constrictions) to observe cellular responses of human RBCs in terms of intracellular Ca2+-signaling by confocal microscopy of Fluo-4 loaded RBCs. We were able to confirm our in vitro results in a mouse dorsal skinfold chamber model showing a transiently increased intracellular Ca2+ when RBCs were passing through small capillaries in vivo. Furthermore, we performed the above-mentioned in vitro experiments as well as measurements of RBCs filterability under various pharmacological manipulations (GsMTx-4, TRAM-34) to explore the molecular mechanism of the Ca2+-signaling. Based on these experiments we conclude that mechanical stimulation of RBCs activates mechano-sensitive channels most likely Piezo1. This channel activity allows Ca2+ to enter the cell, leading to a transient activation of the Gardos-channel associated with K+, Cl−, and water loss, i.e., with a transient volume adaptation facilitating the passage of the RBCs through the constriction. PMID:29259557

Large scale simulation of liquid water transport in a gas diffusion layer of polymer electrolyte membrane fuel cells using the lattice Boltzmann method

NASA Astrophysics Data System (ADS)

Sakaida, Satoshi; Tabe, Yutaka; Chikahisa, Takemi

2017-09-01

A method for the large-scale simulation with the lattice Boltzmann method (LBM) is proposed for liquid water movement in a gas diffusion layer (GDL) of polymer electrolyte membrane fuel cells. The LBM is able to analyze two-phase flows in complex structures, however the simulation domain is limited due to heavy computational loads. This study investigates a variety means to reduce computational loads and increase the simulation areas. One is applying an LBM treating two-phases as having the same density, together with keeping numerical stability with large time steps. The applicability of this approach is confirmed by comparing the results with rigorous simulations using actual density. The second is establishing the maximum limit of the Capillary number that maintains flow patterns similar to the precise simulation; this is attempted as the computational load is inversely proportional to the Capillary number. The results show that the Capillary number can be increased to 3.0 × 10-3, where the actual operation corresponds to Ca = 10-5∼10-8. The limit is also investigated experimentally using an enlarged scale model satisfying similarity conditions for the flow. Finally, a demonstration is made of the effects of pore uniformity in GDL as an example of a large-scale simulation covering a channel.

Visualizing and quantifying the crossover from capillary fingering to viscous fingering in a rough fracture

NASA Astrophysics Data System (ADS)

Chen, Yi-Feng; Fang, Shu; Wu, Dong-Sheng; Hu, Ran

2017-09-01

Immiscible fluid-fluid displacement in permeable media is important in many subsurface processes, including enhanced oil recovery and geological CO2 sequestration. Controlled by capillary and viscous forces, displacement patterns of one fluid displacing another more viscous one exhibit capillary and viscous fingering, and crossover between the two. Although extensive studies investigated viscous and capillary fingering in porous media, a few studies focused on the crossover in rough fractures, and how viscous and capillary forces affect the crossover remains unclear. Using a transparent fracture-visualization system, we studied how the two forces impact the crossover in a horizontal rough fracture. Drainage experiments of water displacing oil were conducted at seven flow rates (capillary number log10Ca ranging from -7.07 to -3.07) and four viscosity ratios (M=1/1000,1/500,1/100 and 1/50). We consistently observed lower invading fluid saturations in the crossover zone. We also proposed a phase diagram for the displacement patterns in a rough fracture that is consistent with similar studies in porous media. Based on real-time imaging and statistical analysis of the invasion morphology, we showed that the competition between capillary and viscous forces is responsible for the saturation reduction in the crossover zone. In this zone, finger propagation toward the outlet (characteristic of viscous fingering) as well as void-filling in the transverse/backward directions (characteristic of capillary fingering), are both suppressed. Therefore, the invading fluid tends to occupy larger apertures with higher characteristic front velocity, promoting void-filling toward the outlet with thinner finger growth and resulting in a larger volume of defending fluid left behind.

Multiplex Ligation-Dependent Probe Amplification Analysis on Capillary Electrophoresis Instruments for a Rapid Gene Copy Number Study

PubMed Central

Jankowski, Stéphane; Currie-Fraser, Erica; Xu, Licen; Coffa, Jordy

2008-01-01

Annotated DNA samples that had been previously analyzed were tested using multiplex ligation-dependent probe amplification (MLPA) assays containing probes targeting BRCA1, BRCA2, and MMR (MLH1/MSH2 genes) and the 9p21 chromosomal region. MLPA polymerase chain reaction products were separated on a capillary electrophoresis platform, and the data were analyzed using GeneMapper v4.0 software (Applied Biosystems, Foster City, CA). After signal normalization, loci regions that had undergone deletions or duplications were identified using the GeneMapper Report Manager and verified using the DyeScale functionality. The results highlight an easy-to-use, optimal sample preparation and analysis workflow that can be used for both small- and large-scale studies. PMID:19137113

Effective slip over partially filled microcavities and its possible failure

NASA Astrophysics Data System (ADS)

Ge, Zhouyang; Holmgren, Hanna; Kronbichler, Martin; Brandt, Luca; Kreiss, Gunilla

2018-05-01

Motivated by the emerging applications of liquid-infused surfaces (LIS), we study the drag reduction and robustness of transverse flows over two-dimensional microcavities partially filled with an oily lubricant. Using separate simulations at different scales, characteristic contact line velocities at the fluid-solid intersection are first extracted from nanoscale phase field simulations and then applied to micronscale two-phase flows, thus introducing a multiscale numerical framework to model the interface displacement and deformation within the cavities. As we explore the various effects of the lubricant-to-outer-fluid viscosity ratio μ˜2/μ˜1 , the capillary number Ca, the static contact angle θs, and the filling fraction of the cavity δ , we find that the effective slip is most sensitive to the parameter δ . The effects of μ˜2/μ˜1 and θs are generally intertwined but weakened if δ <1 . Moreover, for an initial filling fraction δ =0.94 , our results show that the effective slip is nearly independent of the capillary number when it is small. Further increasing Ca to about 0.01 μ˜1/μ˜2 , we identify a possible failure mode, associated with lubricants draining from the LIS, for μ˜2/μ˜1≲0.1 . Very viscous lubricants (e.g., μ˜2/μ˜1>1 ), however, are immune to such failure due to their generally larger contact line velocity.

Pore-scale analysis of the minimum liquid film thickness around elongated bubbles in confined gas-liquid flows

NASA Astrophysics Data System (ADS)

Magnini, M.; Beisel, A. M.; Ferrari, A.; Thome, J. R.

2017-11-01

The fluid mechanics of elongated bubbles in confined gas-liquid flows in micro-geometries is important in pore-scale flow processes for enhanced oil recovery and mobilization of colloids in unsaturated soil. The efficiency of such processes is traditionally related to the thickness of the liquid film trapped between the elongated bubble and the pore's wall, which is assumed constant. However, the surface of long bubbles presents undulations in the vicinity of the rear meniscus, which may significantly decrease the local thickness of the liquid film, thus impacting the process of interest. This study presents a systematic analysis of these undulations and the minimum film thickness induced in the range Ca = 0.001- 0.5 and Re = 0.1- 2000 . Pore-scale Computational Fluid Dynamics (CFD) simulations are performed with a self-improved version of the opensource solver ESI OpenFOAM which is based on a Volume of Fluid method to track the gas-liquid interface. A lubrication model based on the extension of the classical axisymmetric Bretherton theory is utilized to better understand the CFD results. The profiles of the rear meniscus of the bubble obtained with the lubrication model agree fairly well with those extracted from the CFD simulations. This study shows that the Weber number of the flow, We = Ca Re , is the parameter that best describes the dynamics of the interfacial waves. When We < 0.1, a single wave crest is observed and the minimum film thickness tends to an asymptotic value, which depends on the capillary number, as We → 0. Undulations dampen as the capillary number increases and disappear completely when Ca = 0.5 . When We > 0.1, a larger number of wave crests becomes evident on the surface of the rear meniscus of the bubble. The liquid film thickness at the crests of the undulations thins considerably as the Reynolds number is increased, down to less than 60% of the value measured in the flat film region. This may significantly influence important environmental processes, such as the detachment and mobilization of micron-sized pollutants and pathogenic micro-organisms adhering at the pore's wall in unsaturated soil.

Wall slipping behavior of foam with nanoparticle-armored bubbles and its flow resistance factor in cracks.

PubMed

Lv, Qichao; Li, Zhaomin; Li, Binfei; Husein, Maen; Shi, Dashan; Zhang, Chao; Zhou, Tongke

2017-07-11

In this work, wall slipping behavior of foam with nanoparticle-armored bubbles was first studied in a capillary tube and the novel multiphase foam was characterized by a slipping law. A crack model with a cuboid geometry was then used to compare with the foam slipping results from the capillary tube and also to evaluate the flow resistance factor of the foam. The results showed that the slipping friction force F FR in the capillary tube significantly increased by addition of modified SiO 2 nanoparticles, and an appropriate power law exponents by fitting F FR vs. Capillary number, Ca, was 1/2. The modified nanoparticles at the surface were bridged together and formed a dense particle "armor" surrounding the bubble, and the interconnected structures of the "armor" with strong steric integrity made the surface solid-like, which was in agreement with the slip regime associated with rigid surface. Moreover, as confirmed by 3D microscopy, the roughness of the bubble surface increased with nanoparticle concentration, which in turn increased the slipping friction force. Compared with pure SDBS foam, SDBS/SiO 2 foam shows excellent stability and high flow resistance in visual crack. The resistance factor of SiO 2 /SDBS foam increased as the wall surface roughness increased in core cracks.

Steady displacement of long gas bubbles in channels and tubes filled by a Bingham fluid

NASA Astrophysics Data System (ADS)

Zamankhan, Parsa; Takayama, Shuichi; Grotberg, James B.

2018-01-01

Bingham fluids behave like solids below a von Mises stress threshold, the yield stress, while above it they behave like Newtonian fluids. They are characterized by a dimensionless parameter, Bingham number (Bn), which is the ratio of the yield stress to a characteristic viscous stress. In this study, the noninertial steady motion of a finite-size gas bubble in both a plane two-dimensional (2D) channel and an axisymmetric tube filled by a Bingham fluid has been studied numerically. The Bingham number, Bn, is in the range 0 ≤Bn ≤3 , where Bn =0 is the Newtonian case, while the capillary number, which is the ratio of a characteristic viscous force to the surface tension, has values Ca =0.05 ,0.10 , and 0.25. The volume of all axisymmetric and 2D bubbles has been chosen to be identical for all parameter choices and large enough for the bubbles to be long compared to the channel, tube height, and diameter. The Bingham fluid constitutive equation is approximated by a regularized equation. During the motion, the bubble interface is separated from the wall by a static liquid film. The film thickness scaled by the tube radius (axisymmetric) and half of the channel height (2D) is the dimensionless film thickness, h . The results show that increasing Bn initially leads to an increase in h ; however, the profile h versus Bn can be monotonic or nonmonotonic depending on Ca values and 2D or axisymmetric configurations. The yield stress also alters the shape of the front and rear of the bubble and suppresses the capillary waves at the rear of the bubble. The yield stress increases the magnitude of the wall shear stress and its gradient and therefore increases the potential for epithelial cell injuries in applications to lung airway mucus plugs. The topology of the yield surfaces as well as the flow pattern in the bubble frame of reference varies significantly by Ca and Bn.

Drop deformation and breakup in a partially filled horizontal rotating cylinder

NASA Astrophysics Data System (ADS)

White, Andrew; Pereira, Caroline; Hyacinthe, Hyaquino; Ward, Thomas

2014-11-01

Drop deformation and breakup due to shear flow has been studied extensively in Couette devices as well as in gravity-driven flows. In these cases shear is generated either by the moving wall or the drop's motion. For such flows the drop shape remains unperturbed at low capillary number (Ca), deforms at moderate Ca , and can experience breakup as Ca --> 1 and larger. Here single drops of NaOH(aq) will be placed in a horizontal cylindrical rotating tank partially filled with vegetable oil resulting in 10-2 < Ca <101 . It will be shown that the reactive vegetable oil-NaOH(aq) system, where surfactants are produced in situ by saponification, can yield lower minimum surface tensions and faster adsorption than non-reactive surfactant systems. Oil films between the wall and drop as well as drop shape will be observed as rotation rates and NaOH(aq) concentration are varied. Results will be presented in the context of previous work on bubble and drop shapes and breakup. NSF CBET #1262718.

Electroosmotic Push–Pull Perfusion: Description and Application to Qualitative Analysis of the Hydrolysis of Exogenous Galanin in Organotypic Hippocampal Slice Cultures

PubMed Central

2013-01-01

We demonstrate here a method that perfuses a small region of an organotypic hippocampal culture with a solution containing an enzyme substrate, a neuropeptide. Perfusate containing hydrolysis products is continually collected and subsequently analyzed for the products of the enzymatic degradation of the peptide substrate. The driving force for perfusion is an electric field. The fused silica capillaries used as “push” and “pull” or “source” and “collection” capillaries have a ζ-potential that is negative and greater in magnitude than the tissue’s ζ-potential. Thus, depending on the magnitudes of particular dimensions, the electroosmotic flow in the capillaries augments the fluid velocity in the tissue. The flow rate is not directly measured; however, we determine it using a finite-element approach. We have determined the collection efficiency of the system using an all d-amino acid internal standard. The flow rates are low, in the nL/min range, and adjustable by controlling the current or voltage in the system. The collection efficiency of the d-amino acid peptide internal standard is variable, increasing with increased current and thus electroosmotic flow rate. The collection efficiency can be rationalized in the context of a Peclet number. Electroosmotic push–pull perfusion of the neuropeptide galanin (gal1–29) through the extracellular space of an organotypic hippocampal culture results in its hydrolysis by ectopeptidase reactions occurring in the extracellular space. The products of hydrolysis were identified by MALDI-MS. Experiments at two levels of current (8–12 μA and 19–40 μA) show that the probability of seeing hydrolysis products (apparently from aminopeptidases) is greater in the Cornu Ammonis area 3 (CA3) than in the Cornu Ammonis area 1 (CA1) in the higher current experiments. In the lower current experiments, shorter peptide products of aminopeptidases (gal13–29 to gal20–19) are seen with greater frequency in CA3 than in CA1 but there is no statistically significant difference for longer peptides (gal3–29 to gal12–29). PMID:23614879

Comparison of Pore-scale CO2-water-glass System Wettability and Conventional Wettability Measurement on a Flat Plate for Geological CO2 Sequestration

NASA Astrophysics Data System (ADS)

Jafari, M.; Cao, S. C.; Jung, J.

2017-12-01

Goelogical CO2 sequestration (GCS) has been recently introduced as an effective method to mitigate carbon dioxide emission. CO2 from main producer sources is collected and then is injected underground formations layers to be stored for thousands to millions years. A safe and economical storage project depends on having an insight of trapping mechanisms, fluids dynamics, and interaction of fluids-rocks. Among different forces governing fluids mobility and distribution in GCS condition, capillary pressure is of importance, which, in turn, wettability (measured by contact angel (CA)) is the most controversial parameters affecting it. To explore the sources of discrepancy in the literature for CA measurement, we conducted a series of conventional captive bubble test on glass plates under high pressure condition. By introducing a shape factor, we concluded that surface imperfection can distort the results in such tests. Since the conventional methods of measuring the CA is affected by gravity and scale effect, we introduced a different technique to measure pore-scale CA inside a transparent glass microchip. Our method has the ability to consider pore sizes and simulate static and dynamics CA during dewetting and imbibition. Glass plates shows a water-wet behavior (CA 30° - 45°) by a conventional experiment consistent with literature. However, CA of miniature bubbles inside of the micromodel can have a weaker water-wet behavior (CA 55° - 69°). In a more realistic pore-scale condition, water- CO2 interface covers whole width of a pore throats. Under this condition, the receding CA, which is used for injectability and capillary breakthrough pressure, increases with decreasing pores size. On the other hand, advancing CA, which is important for residual or capillary trapping, does not show a correlation with throat sizes. Static CA measured in the pores during dewetting is lower than static CA on flat plate, but it is much higher when measured during imbibition implying weaker water-wet behavior. Pore-scale CA, which realistically represents rocks wettability behavior, shows weaker water-wet behavior than conventional measurement methods, which must be considered for safety of geological storage.

A drop in uniaxial and biaxial nonlinear extensional flows

NASA Astrophysics Data System (ADS)

Favelukis, M.

2017-08-01

In this theoretical report, we explore small deformations of an initially spherical drop subjected to uniaxial or biaxial nonlinear extensional creeping flows. The problem is governed by the capillary number (Ca), the viscosity ratio (λ), and the nonlinear intensity of the flow (E). When the extensional flow is linear (E = 0), the familiar internal circulations are obtained and the same is true with E > 0, except that the external and internal flow rates increase with increasing E. If E < 0, the external flow consists of some unconnected regions leading to the same number of internal circulations (-3/7 < E < 0) or twice the number of internal circulations (E < -3/7), when compared to the linear case. The shape of the deformed drop is represented in terms of a modified Taylor deformation parameter, and the conditions for the breakup of the drop by a center pinching mechanism are also established. When the flow is linear (E = 0), the literature predicts prolate spheroidal drops for uniaxial flows (Ca > 0) and oblate spheroidal drops for biaxial flows (Ca < 0). For the same |Ca|, if E > 0, the drop is more elongated than the linear case, while E < 0 results in less elongated drops than the linear case. Compared to the linear case, for both uniaxial and biaxial extensional flows, E > 0 tends to facilitate drop breakup, while E < 0 makes drop breakup more difficult.

Early changes in fiber profile and capillary density in long-term stimulated muscles.

PubMed

Hudlická, O; Dodd, L; Renkin, E M; Gray, S D

1982-10-01

Predominantly fast skeletal muscles of rabbits [tibialis anterior (TA), extensor digitorum longus (EDL)] were stimulated at a frequency naturally occurring in nerves to slow muscles (10 Hz continuously) for 8 h/day for 2--4 days. Such stimulation is known to convert all glycolytic fibers to oxidative and to increase capillary density. Our aim was to study early stages of conversion to investigate the factors responsible for the changes. Staining of quick-frozen sections for myosin ATPase, succinic dehydrogenase, and alkaline phosphatase was used to study the distribution of different fiber types and to measure fiber cross-sectional areas, capillaries per square millimeter, and capillary-to-fiber ratios in each fiber category. TA but not EDL showed conversion of fast glycolytic to fast oxidative fibers after 2 days, more after 4 days of stimulation. In both muscles, the largest fast glycolytic fibers were diminished in number after stimulation. There was significant increase in total capillaries per square millimeter after 4 days and some increase after 2 days of stimulation. The increase in capillaries per square millimeter exceeded the increase in the number of fibers per square millimeter, and since there was no change in mean fiber area, the increase is attributed to capillary growth. In EDL, there was an increase in the number of capillaries supplying both fast glycolytic and fast oxidative fibers, suggesting that capillary growth precedes fiber type conversion. In TA, the number of capillaries supplying fast oxidative fibers was increased but that to fast glycolytic fibers, was not. This is consistent with capillary growth simultaneous with or following fiber conversion. In both TA and EDL the number of capillaries perfused after contraction was higher in stimulated muscles, suggesting that increased capillary flow contributed to capillary growth.

Iterated Stretching of Viscoelastic Jets

NASA Technical Reports Server (NTRS)

Chang, Hsueh-Chia; Demekhin, Evgeny A.; Kalaidin, Evgeny

1999-01-01

We examine, with asymptotic analysis and numerical simulation, the iterated stretching dynamics of FENE and Oldroyd-B jets of initial radius r(sub 0), shear viscosity nu, Weissenberg number We, retardation number S, and capillary number Ca. The usual Rayleigh instability stretches the local uniaxial extensional flow region near a minimum in jet radius into a primary filament of radius [Ca(1 - S)/ We](sup 1/2)r(sub 0) between two beads. The strain-rate within the filament remains constant while its radius (elastic stress) decreases (increases) exponentially in time with a long elastic relaxation time 3We(r(sup 2, sub 0)/nu). Instabilities convected from the bead relieve the tension at the necks during this slow elastic drainage and trigger a filament recoil. Secondary filaments then form at the necks from the resulting stretching. This iterated stretching is predicted to occur successively to generate high-generation filaments of radius r(sub n), (r(sub n)/r(sub 0)) = square root of 2[r(sub n-1)/r(sub 0)](sup 3/2) until finite-extensibility effects set in.

Motion and shape of partially non-wetting drops on inclined surfaces

NASA Astrophysics Data System (ADS)

Puthenveettil, Baburaj A.; Senthilkumar K, Vijaya; Hopfinger, E. J.; IIT Madras-LEGI Collaboration

2011-11-01

We study high Reynolds number (Re) motion of partially non- wetting liquid drops on inclined surfaces using (i) water on Fluoro-Alkyl Silane (FAS) coated glass and (ii) mercury on glass. The high hysteresis (35°) water drop experiments have been conducted for a range of inclination angles 26° < α <62° which give a range of Capillary numbers 0 . 0003 < Ca < 0 . 0075 and 137 < Re < 3142 . For low hysteresis (6°) mercury on glass experiments, 5 .5° < α < 14 .3° so that 0 . 0002 < Ca < 0 . 0023 and 3037 < Re < 20069 . It is shown that when Re >>103 for water and Re >> 19 for mercury, the observed velocities are accounted for by a boundary layer flow model. The dimensionless velocity in the inertial regime, Ca√{ Re } scales as the modified Bond number (Bom), while Ca Bom at low Re . We show that even at high Re , the dynamic contact angles (θd) depend only on Ca , similar to that in low Re drops. Only the model by Shikhmurzaev is consistent with the variation of dynamic contact angles in both mercury and water drops. We show that the corner transition at the rear of the mercury drop occurs at a finite, receding contact angle, which is predicted by a wedge flow model that we propose. For water drops, there is a direct transition to a rivulet from the oval shape at a critical ratio of receding to static contact angles.

Velocity dependence of biphasic flow structuration: steady-state and oscillating flow effects

NASA Astrophysics Data System (ADS)

Tore Tallakstad, Ken; Jankov, Mihailo; Løvoll, Grunde; Toussaint, Renaud; Jørgen Mâløy, Knut; Grude Flekkøy, Eirik; Schmittbuhl, Jean; Schäfer, Gerhard; Méheust, Yves; Arendt Knudsen, Henning

2010-05-01

We study various types of biphasic flows in quasi-two-dimensional transparent porous models. These flows imply a viscous wetting fluid, and a lowly viscous one. The models are transparent, allowing the displacement process and structure to be monitored in space and time. Three different aspects will be presented: 1. In stationary biphasic flows, we study the relationship between the macroscopic pressure drop (related to relative permeability) and the average flow rate, and how this arises from the cluster size distribution of the lowly viscous fluid [1]. 2. In drainage situations, we study how the geometry of the invader can be explained, and how it gives rise to apparent dynamic capillary effects. We show how these can be explained by viscous effects on evolving geometries of invading fluid [2]. 3. We study the impact of oscillating pressure fields superimposed to a background flow over the flow regimes patterns [3]. Steady-State Two-Phase Flow in Porous Media: Statistics and Transport Properties. First, in stationary flow with a control of the flux of both fluids, we show how the pressure drop depends on the flow rate. We will show that the dynamics is dominated by the interplay between a viscous pressure field from the wetting fluid and bubble transport of a less viscous, nonwetting phase. In contrast with more studied displacement front systems, steady-state flow is in equilibrium, statistically speaking. The corresponding theoretical simplicity allows us to explain a data collapse in the cluster size distribution of lowly viscous fluid in the system, as well as the relation |?P|∞√Ca--. This allows to explain so called relative permeability effects by the morphological changes of the cluster size distribution. Influence of viscous fingering on dynamic saturation-pressure curves in porous media. Next, we study drainage in such models, and investigate the relationship between the pressure field and the morphology of the invading fluid. This allows to model the impact of the saturation changes in the system over the pressure difference between the wetting and non wetting phase. We show that the so-called dynamic effects referred in the hydrology literature of experimentally measured capillary pressure curves might be explained by the combined effect of capillary pressure along the invasion front of the gaseous phase and pressure changes caused by viscous effects. A detailed study of the structure optically followed shows that the geometry of the invader is self-similar with two different behaviors at small and large scales: the structure corresponds to the ones of invasion percolation models at small scales (capillary fingering structures with fractal dimension D=1.83), whereas at large scales, viscous pressure drops dominate over the capillary threshold variations, and the structures are self-similar fingering structures with a fractal dimension corresponding to Dielectric Breakdown Models (variants of the DLA model), with D ≠ƒ 1.5. The cross-over scale is set by the scale at which capillary fluctuations are of the order of the viscous pressure drops. This leads physically to the fact that cross-over scale between the two fingering dimensions, goes like the inverse of the capillary number. This study utilizes these geometrical characteristics of the viscous fingers forming in dynamic drainage, to obtain a meaningfull scaling law for the saturation-pressure curve at finite speed, i.e. the so-called dynamic capillary pressure relations. We thus show how the micromechanical interplay between viscous and capillary forces leads to some pattern formation, which results in a general form of dynamic capillary pressure relations. By combining these detailed informations on the displacement structure with global measures of pressure, saturation and controlling the capillary number Ca, a scaling relation relating pressure, saturation, system size and capillary number is developed. By applying this scaling relation, pressure-saturation curves for a wide range of capillary numbers can be collapsed. Effects of pressure oscillations on drainage in an elastic porous medium: The effects of seismic stimulation on the flow of two immiscible fluids in an elastic synthetic porous medium is experimentally investigated. A wetting fluid is slowly evacuated from the medium, while a pressure oscillation is applied on the injected non-wetting fluid. The amplitude and frequency of the pressure oscillations as well as the evacuation speed are kept constant throughout an experiment. The resulting morphology of the invading structure is found to be strongly dependent on the interplay between the amplitude and the frequency of the applied pressure oscillations and the elasticity of the porous medium. Different combinations of these properties yield morphologically similar structures, allowing a classification of structures that is found to depend on a proposed dimensionless number. [1] Tallakstad, K.T., H.A. Knudsen, T. Ramstad, G. Løvoll, K.J. Maløy, R. Toussaint and E.G. Flekkøy , Steady-state two-phase flow in porous media: statistics and transport properties, Phys. Rev. Lett. 102, 074502 (2009). doi:10.1103/PhysRevLett.102.074502 [2] Løvoll, G., M. Jankov, K.J. Maløy, R. Toussaint, J. Schmittbuhl, G. Schaefer and Y. Ḿ eheust, Influence of viscous fingering on dynamic saturation-pressure curves in porous media, submitted to Transport In Porous Media, (2010) [3] Jankov, M., G. Løvoll, H.A. Knudsen, K.J. Maløy, R. Planet, R. Toussaint and E.G. Flekkøy; Effects of pressure oscillations on drainage in an elastic porous medium, Transport In Porous Media, in press (2010).

Migration And Entrapment Of Mercury In The Subsurface

NASA Astrophysics Data System (ADS)

M, D.; Nambi, I. M.

2009-12-01

Elemental mercury is an immiscible liquid with high density and high surface tension. The movement of mercury in the saturated subsurface region is therefore considered a case of two phase flow involving mercury and water and is expected to be governed by gravity, viscous and capillary forces. Fundamental investigation into the migration and capillary entrapment of mercury in the subsurface was done by controlled laboratory capillary pressure saturation experiments using mercury and water as non wetting and wetting fluid respectively. Residual mercury saturation and van Genuchten’s capillary entrapment parameters were determined independently for different sizes of porous media. Based on the experimental data, theoretical investigations were done on the role of the three predominant forces and their influence on mercury migration and entrapment. The effects of fluid density and interfacial tension and the influence of Capillary and Bond number on mercury entrapment were analyzed with the help of similar capillary pressure - saturation experiments using Tetrachloroethylene (PCE)-water fluid pair. Mercury-water systems exhibited a low residual saturation of 0.02 and 0.07 as compared to 0.16 and 0.27 for PCE-water systems. Less residual mercury saturation, lack of apparent hysteresis in capillary pressure saturation curves and large variation in van Genuchten’s parameters 'α'(inverse of displacement pressure) and ‘n’ (pore size distribution index) for mercury-water systems compared to PCE-water systems were observed. These anomalies between the two systems elucidate that the capillary trapping is equally dependent on the fluid characteristics especially for high density immiscible fluids. Gravity force nevertheless a predominant controlling factor in the migration of highly dense mercury, is counteracted by not less trivial capillary force which was 1.22x104 times higher than gravity force. The capillary forces thus surmount the gravity forces and cause entrapment of mercury in the soil pores even in homogeneous porous medium system. Bond number (Bond number relates gravity and capillary forces) for mercury-water system was found to 2.5 times higher than PCE-water systems. Large density differences between mercury and water lead to high Bond number and thus less residual saturation. Capillary number (Capillary number relates viscous and capillary forces) was found to be less for mercury-water systems. Literature review unveils that low Capillary number does not influence non wetting residual saturation. But for high density mercury with natural infiltration, even low Capillary number influences residual saturation. With the alarming increase in number of mercury spill sites, results of this study showed a better understanding of the capillary entrapment phenomena and the extent of influence of each predominant force during displacement of highly dense mercury. The fundamental inputs to NAPL entrapment models were generated in this study for mercury for the first time. This data will be used to assess the distribution of mercury in contaminated sites and design suitable remedial alternatives.

Fibro-vascular coupling in the control of cochlear blood flow.

PubMed

Dai, Min; Shi, Xiaorui

2011-01-01

Transduction of sound in the cochlea is metabolically demanding. The lateral wall and hair cells are critically vulnerable to hypoxia, especially at high sound levels, and tight control over cochlear blood flow (CBF) is a physiological necessity. Yet despite the importance of CBF for hearing, consensus on what mechanisms are involved has not been obtained. We report on a local control mechanism for regulating inner ear blood flow involving fibrocyte signaling. Fibrocytes in the super-strial region are spatially distributed near pre-capillaries of the spiral ligament of the albino guinea pig cochlear lateral wall, as demonstrably shown in transmission electron microscope and confocal images. Immunohistochemical techniques reveal the inter-connected fibrocytes to be positive for Na+/K+ ATPase β1 and S100. The connected fibrocytes display more Ca(2+) signaling than other cells in the cochlear lateral wall as indicated by fluorescence of a Ca(2+) sensor, fluo-4. Elevation of Ca(2+) in fibrocytes, induced by photolytic uncaging of the divalent ion chelator o-nitrophenyl EGTA, results in propagation of a Ca(2+) signal to neighboring vascular cells and vasodilation in capillaries. Of more physiological significance, fibrocyte to vascular cell coupled signaling was found to mediate the sound stimulated increase in cochlear blood flow (CBF). Cyclooxygenase-1 (COX-1) was required for capillary dilation. The findings provide the first evidence that signaling between fibrocytes and vascular cells modulates CBF and is a key mechanism for meeting the cellular metabolic demand of increased sound activity.

Dynamic behaviors of liquid droplets on a gas diffusion layer surface: Hybrid lattice Boltzmann investigation

NASA Astrophysics Data System (ADS)

Wu, Jie; Huang, Jun-Jie

2015-07-01

Water management is one of the key issues in proton exchange membrane fuel cells. Fundamentally, it is related to dynamic behaviors of droplets on a gas diffusion layer (GDL) surface, and consequently they are investigated in this work. A two-dimensional hybrid method is employed to implement numerical simulations, in which the flow field is solved by using the lattice Boltzmann method and the interface between droplet and gas is captured by solving the Cahn-Hilliard equation directly. One or two liquid droplets are initially placed on the GDL surface of a gas channel, which is driven by the fully developed Poiseuille flow. At a fixed channel size, the effects of viscosity ratio of droplet to gas ( μ ∗ ), Capillary number (Ca, ratio of gas viscosity to surface tension), and droplet interaction on the dynamic behaviors of droplets are systematically studied. By decreasing viscosity ratio or increasing Capillary number, the single droplet can detach from the GDL surface easily. On the other hand, when two identical droplets stay close to each other or a larger droplet is placed in front of a smaller droplet, the removal of two droplets is promoted.

Experimental investigation of a bioartificial capsule flowing in a narrow tube

NASA Astrophysics Data System (ADS)

Risso, Frédéric; Collé-Paillot, Fabienne; Zagzoule, Mokhtar

This work is an experimental study of the motion and deformation of a bioartificial capsule flowing in a tube of 4 mm diameter. The capsules, initially designed for medical applications, are droplets of salt water surrounded by a thin polymeric membrane. They are immersed in a very viscous Newtonian silicone oil that flows through a tube in the Stokes regime. The properties of the capsules were carefully determined. Two previous experimental papers were devoted to their characterization by osmotic swelling and compression between two plates. The present work also provides a series of tests that allows an accurate definition of the experimental model under investigation. The capsules are buoyant and initially quasi-spherical. Nevertheless, buoyancy and small departures from sphericity are shown to have no significant effects, provided the flowing velocity is large enough for the viscous stress to become predominant. The capsules are also initially slightly over-inflated, but there is no mass transfer through the membrane during the present experiments. Their volume therefore remains constant. The membrane can be described as an elastic two-dimensional material, the elastic moduli of which are independent of the deformation. Far from the tube ends, the capsule reaches a steady state that depends on two parameters: the capillary number, Ca; and the ratio of the radius of the capsule to that of the tube, a/R. The capillary number, which compares the hydrodynamic stresses to the elastic tensions in the membrane, was varied between 0 and 0.125. The radius ratio, which measures the magnitude of the confinement, was varied from 0.75 to 0.95. In the range investigated, the membrane material always remains in the elastic domain. At fixed a/R, the capsule is stretched in the axial direction when Ca is increased. The process of deformation involves two main stages. At small to moderate Ca, the lateral dimension of the capsule decreases whereas its axial length increases. The capsule is rounded at both ends, but the curvature of its rear decreases as Ca increases. At large Ca, the rear buckles inward. Then, the negative rear curvature goes on decreasing whereas the lateral dimension of the capsule reaches a constant value. On the other hand, increasing a/R promotes the deformation: the process remains qualitatively the same, but the different stages are attained for smaller values of Ca. Comparisons with available numerical simulations show that the results are strongly dependent on the properties of the capsules.

Pore-scale modeling of wettability effects on CO2-brine displacement during geological storage

NASA Astrophysics Data System (ADS)

Basirat, Farzad; Yang, Zhibing; Niemi, Auli

2017-11-01

Wetting properties of reservoir rocks and caprocks can vary significantly, and they strongly influence geological storage of carbon dioxide in deep saline aquifers, during which CO2 is supposed to displace the resident brine and to become permanently trapped. Fundamental understanding of the effect of wettability on CO2-brine displacement is thus important for improving storage efficiency and security. In this study, we investigate the influence of wetting properties on two-phase flow of CO2 and brine at the pore scale. A numerical model based on the phase field method is implemented to simulate the two-phase flow of CO2-brine in a realistic pore geometry. Our focus is to study the pore-scale fluid-fluid displacement mechanisms under different wetting conditions and to quantify the effect of wettability on macroscopic parameters such as residual brine saturation, capillary pressure, relative permeability, and specific interfacial area. Our simulation results confirm that both the trapped wetting phase saturation and the normalized interfacial area increase with decreasing contact angle. However, the wetting condition does not appear to influence the CO2 breakthrough time and saturation. We also show that the macroscopic capillary pressures based on the pressure difference between inlet and outlet can differ significantly from the phase averaging capillary pressures for all contact angles when the capillary number is high (log Ca > -5). This indicates that the inlet-outlet pressure difference may not be a good measure of the continuum-scale capillary pressure. In addition, the results show that the relative permeability of CO2 can be significantly lower in strongly water-wet conditions than in the intermediate-wet conditions.

Effects of gravity, inertia, and surfactant on steady plug propagation in a two-dimensional channel

NASA Astrophysics Data System (ADS)

Zheng, Y.; Fujioka, H.; Grotberg, J. B.

2007-08-01

Liquid plugs may form in pulmonary airways during the process of liquid instillation or removal in many clinical treatments. Studies have shown that the effectiveness of these treatments may depend on how liquids distribute in the lung. Better understanding of the fundamental fluid mechanics of liquid plug transport will facilitate treatment strategies. In this paper, we develop a numerical model of steady plug propagation driven by gravity and pressure in a two-dimensional liquid-lined channel oriented at an angle α with respect to gravity. We investigate the effects of gravity through the Bond number, Bo, and α; the plug propagation speed through the capillary number, Ca, or the Reynolds number, Re; the plug length LP, and the surfactant concentration C0. Without gravity, i.e., Bo =0, the plug is symmetric, and there are two regimes for the flow: two wall layers and two trapped vortices in the core. There is no flow interaction between the upper and lower half plug domains. When Bo ≠0 and α ≠0, π, fluid is found to flow from the upper precursor film, through the core and into the lower trailing film. Then the number of vortices can be zero, one, or two, depending on the flow parameters. The vortices have stagnation points on the interface when C0=0, however when the surfactant is present (C0>0), the vortices detach from the interface and create saddle points inside the core. The front meniscus develops a capillary surface wave extending into the precursor film. This is where the film is thinnest and thus the wall shear stress is highest, as high as ˜100dyn /cm2 in adult airways, which indicates a significant risk of pulmonary airway epithelial cell damage. Adding surfactant can decrease the peak magnitude of the shear stress, thus reducing the risk of cell damage. The prebifurcation asymmetry of the plug is quantified by the volume ratio, Vr, defined as the ratio of the liquid above to that below the center line of the channel. Vr is found to increase with LP, Ca, Re, and C0, while it decreases with Bo. The total mass left behind in the trailing films increases with Bo for any α at α >2π/5, Ca and α for any value of Bo >0.

Modeling oxygen transport in human placental terminal villi.

PubMed

Gill, J S; Salafia, C M; Grebenkov, D; Vvedensky, D D

2011-12-21

Oxygen transport from maternal blood to fetal blood is a primary function of the placenta. Quantifying the effectiveness of this exchange remains key in identifying healthy placentas because of the great variability in capillary number, caliber and position within the villus-even in placentas deemed clinically "normal". By considering villous membrane to capillary membrane transport, stationary oxygen diffusion can be numerically solved in terminal villi represented by digital photomicrographs. We aim to provide a method to determine whether and if so to what extent diffusional screening may operate in placental villi. Segmented digital photomicrographs of terminal villi from the Pregnancy, Infection and Nutrition study in North Carolina 2002 are used as a geometric basis for solving the stationary diffusion equation. Constant maternal villous oxygen concentration and perfect fetal capillary membrane absorption are assumed. System efficiency is defined as the ratio of oxygen flux into a villus and the sum of the capillary areas contained within. Diffusion screening is quantified by comparing numerical and theoretical maximum oxygen fluxes. A strong link between various measures of villous oxygen transport efficiency and the number of capillaries within a villus is established. The strength of diffusional screening is also related to the number of capillaries within a villus. Our measures of diffusional efficiency are shown to decrease as a function of the number of capillaries per villus. This low efficiency, high capillary number relationship supports our hypothesis that diffusional screening is present in this system. Oxygen transport per capillary is reduced when multiple capillaries compete for diffusing oxygen. A complete picture of oxygen fluxes, capillary and villus areas is obtainable and presents an opportunity for future work. Copyright © 2011 Elsevier Ltd. All rights reserved.

Motion of deformable drops through granular media and other confined geometries.

PubMed

Davis, Robert H; Zinchenko, Alexander Z

2009-06-15

This article features recent simulation studies of the flow of emulsions containing deformable drops through pores, constrictions, and granular media. The flow is assumed to be at low Reynolds number, so that viscous forces dominate, and boundary-integral methods are used to determine interfacial velocities and, hence, track the drop motion and shapes. A single drop in a flat channel migrates to the channel centerplane due to deformation-induced drift, which increases its steady-state velocity along the channel. A drop moving towards a smaller interparticle constriction squeezes through the constriction if the capillary number (ratio of viscous deforming forces and interfacial tension forces) is large enough, but it becomes trapped when the capillary number is below a critical value. These concepts then influence the flow of an emulsion through a granular medium, for which the drop phase moves faster than the suspending liquid at large capillary numbers but slower than the suspending liquid at smaller capillary numbers. The permeabilities of the granular medium to both phases increase with increasing capillary number, due to the reduced resistance to squeezing of easily deformed drops, though drop breakup must also be considered at large capillary numbers.

MULTILEVEL ISCHEMIA IN DISORGANIZATION OF THE RETINAL INNER LAYERS ON PROJECTION-RESOLVED OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY.

PubMed

Onishi, Alex C; Ashraf, Mohammed; Soetikno, Brian T; Fawzi, Amani A

2018-04-10

To examine the relationship between ischemia and disorganization of the retinal inner layers (DRIL). Cross-sectional retrospective study of 20 patients (22 eyes) with diabetic retinopathy presenting to a tertiary academic referral center, who had DRIL on structural optical coherence tomography (OCT) using Spectralis HRA + OCT (Heidelberg Engineering, Heidelberg, Germany) and OCT angiography with XR Avanti (Optovue Inc, Fremont, CA) on the same day. Optical coherence tomography angiography images were further processed to remove flow signal projection artifacts using a software algorithm adapted from recent studies. Retinal capillary perfusion in the superficial capillary plexuses, middle capillary plexuses, and deep capillary plexuses, as well as integrity of the photoreceptor lines on OCT was compared in areas with DRIL to control areas without DRIL in the same eye. Qualitative assessment of projection-resolved OCT angiography of eyes with DRIL on structural OCT demonstrated significant perfusion deficits compared with adjacent control areas (P < 0.001). Most lesions (85.7%) showed superimposed superficial capillary plexus and/or middle capillary plexus nonperfusion in addition to deep capillary plexus nonflow. Areas of DRIL were significantly associated with photoreceptor disruption (P = 0.035) compared with adjacent DRIL-free areas. We found that DRIL is associated with multilevel retinal capillary nonperfusion, suggesting an important role for ischemia in this OCT phenotype.

Quantitative analysis of nailfold capillary morphology in patients with fibromyalgia

PubMed Central

Choi, Dug-Hyun

2015-01-01

Background/Aims Nailfold capillaroscopy (NFC) has been used to examine morphological and functional microcirculation changes in connective tissue diseases. It has been demonstrated that NFC patterns reflect abnormal microvascular dynamics, which may play a role in fibromyalgia (FM) syndrome. The aim of this study was to determine NFC patterns in FM, and their association with clinical features of FM. Methods A total of 67 patients with FM, and 30 age- and sex-matched healthy controls, were included. Nailfold capillary patterns were quantitatively analyzed using computerized NFC. The parameters of interest were as follows: number of capillaries within the central 3 mm, deletion score, apical limb width, capillary width, and capillary dimension. Capillary dimension was determined by calculating the number of capillaries using the Adobe Photoshop version 7.0. Results FM patients had a lower number of capillaries and higher deletion scores on NFC compared to healthy controls (17.3 ± 1.7 vs. 21.8 ± 2.9, p < 0.05; 2.2 ± 0.9 vs. 0.7 ± 0.6, p < 0.05, respectively). Both apical limb width (µm) and capillary width (µm) were significantly decreased in FM patients (1.1 ± 0.2 vs. 3.7 ± 0.6; 5.4 ± 0.5 vs. 7.5 ± 1.4, respectively), indicating that FM patients have abnormally decreased digital capillary diameter and density. Interestingly, there was no difference in capillary dimension between the two groups, suggesting that the length or tortuosity of capillaries in FM patients is increased to compensate for diminished microcirculation. Conclusions FM patients had altered capillary density and diameter in the digits. Diminished microcirculation on NFC may alter capillary density and increase tortuosity. PMID:26161020

In Vivo Microscopy Reveals Extensive Embedding of Capillaries within the Sarcolemma of Skeletal Muscle Fibers

PubMed Central

Glancy, Brian; Hsu, Li-Yueh; Dao, Lam; Bakalar, Matthew; French, Stephanie; Chess, David J.; Taylor, Joni L.; Picard, Martin; Aponte, Angel; Daniels, Mathew P.; Esfahani, Shervin; Cushman, Samuel; Balaban, Robert S.

2013-01-01

Objective To provide insight into mitochondrial function in vivo, we evaluated the 3D spatial relationship between capillaries, mitochondria, and muscle fibers in live mice. Methods 3D volumes of in vivo murine Tibialis anterior muscles were imaged by multi-photon microscopy (MPM). Muscle fiber type, mitochondrial distribution, number of capillaries, and capillary-to-fiber contact were assessed. The role of myoglobin-facilitated diffusion was examined in myoglobin knockout mice. Distribution of GLUT4 was also evaluated in the context of the capillary and mitochondrial network. Results MPM revealed that 43.6 ± 3.3% of oxidative fiber capillaries had ≥ 50% of their circumference embedded in a groove in the sarcolemma, in vivo. Embedded capillaries were tightly associated with dense mitochondrial populations lateral to capillary grooves and nearly absent below the groove. Mitochondrial distribution, number of embedded capillaries, and capillary-to-fiber contact were proportional to fiber oxidative capacity and unaffected by myoglobin knockout. GLUT4 did not preferentially localize to embedded capillaries. Conclusions Embedding capillaries in the sarcolemma may provide a regulatory mechanism to optimize delivery of oxygen to heterogeneous groups of muscle fibers. We hypothesize that mitochondria locate to paravascular regions due to myofibril voids created by embedded capillaries, not to enhance the delivery of oxygen to the mitochondria. PMID:25279425

Electrohydrodynamics of a viscous drop with inertia.

PubMed

Nganguia, H; Young, Y-N; Layton, A T; Lai, M-C; Hu, W-F

2016-05-01

Most of the existing numerical and theoretical investigations on the electrohydrodynamics of a viscous drop have focused on the creeping Stokes flow regime, where nonlinear inertia effects are neglected. In this work we study the inertia effects on the electrodeformation of a viscous drop under a DC electric field using a novel second-order immersed interface method. The inertia effects are quantified by the Ohnesorge number Oh, and the electric field is characterized by an electric capillary number Ca_{E}. Below the critical Ca_{E}, small to moderate electric field strength gives rise to steady equilibrium drop shapes. We found that, at a fixed Ca_{E}, inertia effects induce larger deformation for an oblate drop than a prolate drop, consistent with previous results in the literature. Moreover, our simulations results indicate that inertia effects on the equilibrium drop deformation are dictated by the direction of normal electric stress on the drop interface: Larger drop deformation is found when the normal electric stress points outward, and smaller drop deformation is found otherwise. To our knowledge, such inertia effects on the equilibrium drop deformation has not been reported in the literature. Above the critical Ca_{E}, no steady equilibrium drop deformation can be found, and often the drop breaks up into a number of daughter droplets. In particular, our Navier-Stokes simulations show that, for the parameters we use, (1) daughter droplets are larger in the presence of inertia, (2) the drop deformation evolves more rapidly compared to creeping flow, and (3) complex distribution of electric stresses for drops with inertia effects. Our results suggest that normal electric pressure may be a useful tool in predicting drop pinch-off in oblate deformations.

Effect of anti-vertigo granule on the opening number and blood flow of mouse ear capillary network

NASA Astrophysics Data System (ADS)

Li, Chongxian; Liu, Xiaobin; Li, Jun; Hao, Shaojun; Wang, Xidong; Li, Wenjun; Zhang, Zhengchen

2018-04-01

To observe the effects of anti-glare particles on the open number and blood flow in the auricle of mice with microcirculation disturbance model. Sixty mice, half male and half female, were randomly divided into 6 groups. The mice were given Kangxuan granule suspension, serum brain granule suspension and normal saline of the same volume, respectively, once a day. The mice were anesthetized by intraperitoneal injection of chloral hydrate at 1 hour after the last administration. The mouse was fixed on the observation platform and the auricle was placed on the transmission stage. BZ-2000 microcirculation microscope and microcirculation analysis system were used to observe the changes of blood velocity and capillary opening volume in auricle of mice before administration. The changes of blood velocity and capillaries opening volume of mouse auricle were observed 2 min after epinephrine injection into tail vein of mice. Bear fruit: Compared with those before epinephrine, the opening number of capillary reticulum of auricle in large dose Kangxuan granule group was significantly decreased (P<0.05), and in normal saline group and middle group. In the small dose Kangxuan granule group, the opening number of capillary network of auricle decreased significantly (P<0.01). Compared with the model group, the large dose Kangxuan granule group could significantly increase the opening number of the auricle capillary network in mice (P<0.01). Yangxuannao granule group could significantly increase the opening number of auricle capillary reticulum in mice (P<0.05), compared with the model group by Ridit test. Both Kangxuan granule group and Yangxuannao granule group could significantly improve the auricle hair of mice with microcirculation disorder. The blood flow in fine blood vessels (P<0.01). Kangxuan granule has a good effect on the opening number of capillary network of auricle and blood flow in mice with microcirculation disorder.

Single-step reinforced microextraction of polycyclic aromatic hydrocarbons from soil samples using an inside needle capillary adsorption trap with electropolymerized aniline/multi-walled carbon nanotube sorbent.

PubMed

Ghiasvand, Ali Reza; Yazdankhah, Fatemeh

2017-03-03

A polyaniline/multi-wall carbon nanotubes (PANI/MWCNT) composite was electrodeposited on the interior surface of a platinized stainless steel capillary needle and used to prepare an inside needle capillary adsorption trap (INCAT) device. The platinization expanded the interior adsorbing surface of the needle and made it more porous and cohesive for nanocomposite film. The nanocomposite was characterized using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The fabricated INCAT was fixed into a cooling capsule to fabricate a cooling-assisted INCAT (CA-INCAT) system. The CA-INCAT device was used to extract polycyclic aromatic hydrocarbons (PAHs) from solid samples followed by gas chromatography-flame ionization detection (GC-FID) determination. To obtain the best extraction efficiency, the important experimental variables were studied and optimized. Under the optimal conditions, the limits of detection (LODs) for the studied PAHs were in the range of 0.002-0.02ngg -1 . Linear dynamic ranges (LDRs) for the calibration curves were found to be 0.1-30,000ngg -1 . Relative standard deviations (RSDs%) for six replicated analysis of 1ngg -1 PAHs were obtained 7.7-11%. The CA-INCAT-GC-FID method was successfully applied for the extraction and determination of PAHs in contaminated soil samples. The results were in agreement with those obtained by a validated ultrasound-assisted solvent extraction (UA-SE) method. Copyright © 2017 Elsevier B.V. All rights reserved.

Visualization and quantification of two-phase flow in transparent miniature packed beds

NASA Astrophysics Data System (ADS)

Zhu, Peixi; Papadopoulos, Kyriakos D.

2012-10-01

Optical microscopy was used to visualize the flow of two phases [British Petroleum (BP) oil and an aqueous surfactant phase] in confined space, three-dimensional, transparent, natural porous media. The porous media consisted of water-wet cryolite grains packed inside cylindrical, glass microchannels, thus producing microscopic packed beds. Primary drainage of BP oil displacing an aqueous surfactant phase was studied at capillary numbers that varied between 10-6 and 10-2. The confinement space had a significant effect on the flow behavior. Phenomena of burst motion and capillary fingering were observed for low capillary numbers due to the domination of capillary forces. It was discovered that breakthrough time and capillary number bear a log-log scale linear relationship, based on which a generalized correlation between oil travel distance x and time t was found empirically.

Visualization and quantification of two-phase flow in transparent miniature packed beds.

PubMed

Zhu, Peixi; Papadopoulos, Kyriakos D

2012-10-01

Optical microscopy was used to visualize the flow of two phases [British Petroleum (BP) oil and an aqueous surfactant phase] in confined space, three-dimensional, transparent, natural porous media. The porous media consisted of water-wet cryolite grains packed inside cylindrical, glass microchannels, thus producing microscopic packed beds. Primary drainage of BP oil displacing an aqueous surfactant phase was studied at capillary numbers that varied between 10(-6) and 10(-2). The confinement space had a significant effect on the flow behavior. Phenomena of burst motion and capillary fingering were observed for low capillary numbers due to the domination of capillary forces. It was discovered that breakthrough time and capillary number bear a log-log scale linear relationship, based on which a generalized correlation between oil travel distance x and time t was found empirically.

Polyamidoamine dendrimer as a spacer for the immobilization of glucose oxidase in capillary enzyme microreactor.

PubMed

Wang, Siming; Su, Ping; Hongjun, E; Yang, Yi

2010-10-15

Polyamidoamine dendrimer (PAMAM) is one of a number of dendritic polymers with precise molecular structure, highly geometric symmetry, and a large number of terminal groups. In this study, different generations of PAMAM (G0-G4) were introduced onto the inner wall of fused-silica capillaries by microwave irradiation and a new type of glucose oxidase (GOx) capillary enzyme microreactor was developed based on enzyme immobilization in the prepared PAMAM-grafted fused-silica capillaries. The optimal enzymolysis conditions for beta-d-glucose in the microreactor were evaluated by capillary zone electrophoresis. In addition, the enzymolysis efficiencies of different generations of PAMAM-GOx capillary enzyme microreactor were compared. The results indicate that enzymolysis efficiency increased with increasing generations of PAMAM. The experimental results provide the possibility for the development and application of an online immobilized capillary enzyme microreactor. Crown Copyright 2010. Published by Elsevier Inc. All rights reserved.

Micro-injector for capillary electrophoresis.

PubMed

Sáiz, Jorge; Koenka, Israel Joel; García-Ruiz, Carmen; Müller, Beat; Chwalek, Thomas; Hauser, Peter C

2015-08-01

A novel micro-injector for capillary electrophoresis for the handling of samples with volumes down to as little as 300 nL was designed and built in our laboratory for analyses in which the available volume is a limitation. The sample is placed into a small cavity located directly in front of the separation capillary, and the injection is then carried out automatically by controlled pressurization of the chamber with compressed air. The system also allows automated flushing of the injection chamber as well as of the capillary. In a trial with a capillary electrophoresis system with contactless conductivity detector, employing a capillary of 25 μm diameter, the results showed good stability of migration times and peak areas. To illustrate the technique, the fast separation of five inorganic cations (Na(+) , K(+) , NH4 (+) , Ca(2+) , and Mg(2+) ) was set up. This could be achieved in less than 3 min, with good limits of detection (10 μM) and linear ranges (between about 10 and 1000 μM). The system was demonstrated for the determination of the inorganic cations in porewater samples of a lake sediment core. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electroosmotic Sampling. Application to Determination of Ectopeptidase Activity in Organotypic Hippocampal Slice Cultures

PubMed Central

Xu, Hongjuan; Guy, Yifat; Hamsher, Amy; Shi, Guoyue; Sandberg, Mats; Weber, Stephen G.

2010-01-01

We hypothesize that peptide-containing solutions pulled through tissue should reveal the presence and activity of peptidases in the tissue. Using the natural ζ-potential in the organotypic hippocampal slice culture (OHSC), physiological fluids can be pulled through the tissue with an electric field. The hydrolysis of the peptides present in the fluid drawn through the tissue can be determined using capillary HPLC with electrochemical detection of the biuret complexes of the peptides following a postcolumn reaction. We have characterized this new sampling method by measuring the flow rate, examining the use of internal standards, and examining cell death caused by sampling. The sampling flow rate ranges from 60 to 150 nL/min with a 150 μm (ID) sampling capillary with an electric field (at the tip of the capillary) from 30 to 60 V/cm. Cell death can be negligible with controlled sampling conditions. Using this sampling approach, we have electroosmotically pulled Leu-enkephalin through OHSCs to identify ectopeptidase activity in the CA3 region. These studies show that a bestatin-sensitive aminopeptidase may be critical for the hydrolysis of exogenous Leu-enkephalin, a neuropeptide present in the CA3 region of OHSCs. PMID:20669992

VEGF-induced neoangiogenesis is mediated by NAADP and two-pore channel-2–dependent Ca2+ signaling

PubMed Central

Favia, Annarita; Desideri, Marianna; Gambara, Guido; D’Alessio, Alessio; Ruas, Margarida; Esposito, Bianca; Del Bufalo, Donatella; Parrington, John; Ziparo, Elio; Palombi, Fioretta; Galione, Antony; Filippini, Antonio

2014-01-01

Vascular endothelial growth factor (VEGF) and its receptors VEGFR1/VEGFR2 play major roles in controlling angiogenesis, including vascularization of solid tumors. Here we describe a specific Ca2+ signaling pathway linked to the VEGFR2 receptor subtype, controlling the critical angiogenic responses of endothelial cells (ECs) to VEGF. Key steps of this pathway are the involvement of the potent Ca2+ mobilizing messenger, nicotinic acid adenine-dinucleotide phosphate (NAADP), and the specific engagement of the two-pore channel TPC2 subtype on acidic intracellular Ca2+ stores, resulting in Ca2+ release and angiogenic responses. Targeting this intracellular pathway pharmacologically using the NAADP antagonist Ned-19 or genetically using Tpcn2−/− mice was found to inhibit angiogenic responses to VEGF in vitro and in vivo. In human umbilical vein endothelial cells (HUVECs) Ned-19 abolished VEGF-induced Ca2+ release, impairing phosphorylation of ERK1/2, Akt, eNOS, JNK, cell proliferation, cell migration, and capillary-like tube formation. Interestingly, Tpcn2 shRNA treatment abolished VEGF-induced Ca2+ release and capillary-like tube formation. Importantly, in vivo VEGF-induced vessel formation in matrigel plugs in mice was abolished by Ned-19 and, most notably, failed to occur in Tpcn2−/− mice, but was unaffected in Tpcn1−/− animals. These results demonstrate that a VEGFR2/NAADP/TPC2/Ca2+ signaling pathway is critical for VEGF-induced angiogenesis in vitro and in vivo. Given that VEGF can elicit both pro- and antiangiogenic responses depending upon the balance of signal transduction pathways activated, targeting specific VEGFR2 downstream signaling pathways could modify this balance, potentially leading to more finely tailored therapeutic strategies. PMID:25331892

Bicarbonate absorption stimulates active calcium absorption in the rat proximal tubule.

PubMed Central

Bomsztyk, K; Calalb, M B

1988-01-01

To evaluate the effect of luminal bicarbonate on calcium reabsorption, rat proximal tubules were perfused in vivo. Perfusion solution contained mannitol to reduce water flux to zero. Total Ca concentration was measured by atomic absorption spectrometry, Ca ion concentration in the tubule lumen (CaL2+) and the peritubular capillary (CaP2+), and luminal pH (pHL) with ion-selective microelectrodes and transepithelial voltage (VTE) with conventional microelectrodes. When tubules were perfused with buffer-free Cl-containing solution, net Ca absorption (JCa) averaged 3.33 pmol/min. Even though VTE was 1.64 mV lumen-positive, CaL2+, 1.05 mM, did not fall below the concentration in the capillary blood, 1.07 mM. When 27 mM of Cl was replaced with HCO3, there was luminal fluid acidification. Despite a decrease in VTE and CaL2+, JCa increased to 7.13 pmol/min, indicating that the enhanced JCa could not be accounted for by the reduced electrochemical gradient, delta CCa. When acetazolamide or an analogue of amiloride was added to the HCO3 solution, JCa was not different from the buffer-free solution, suggesting that HCO3-stimulated JCa may be linked to acidification. To further test this hypothesis, we used 27 mM Hepes as the luminal buffer. With Hepes there was luminal fluid acidification and JCa was not different from the buffer-free solution but delta CCa was significantly reduced, indicating enhanced active calcium transport. We conclude from the results of the present study that HCO3 stimulates active Ca absorption, a process that may be linked to acidification-mediated HCO3 absorption. PMID:3366902

Liquid toroidal drop under uniform electric field

NASA Astrophysics Data System (ADS)

Zabarankin, Michael

2017-06-01

The problem of a stationary liquid toroidal drop freely suspended in another fluid and subjected to an electric field uniform at infinity is addressed analytically. Taylor's discriminating function implies that, when the phases have equal viscosities and are assumed to be slightly conducting (leaky dielectrics), a spherical drop is stationary when Q=(2R2+3R+2)/(7R2), where R and Q are ratios of the phases' electric conductivities and dielectric constants, respectively. This condition holds for any electric capillary number, CaE, that defines the ratio of electric stress to surface tension. Pairam and Fernández-Nieves showed experimentally that, in the absence of external forces (CaE=0), a toroidal drop shrinks towards its centre, and, consequently, the drop can be stationary only for some CaE>0. This work finds Q and CaE such that, under the presence of an electric field and with equal viscosities of the phases, a toroidal drop having major radius ρ and volume 4π/3 is qualitatively stationary-the normal velocity of the drop's interface is minute and the interface coincides visually with a streamline. The found Q and CaE depend on R and ρ, and for large ρ, e.g. ρ≥3, they have simple approximations: Q˜(R2+R+1)/(3R2) and CaE∼3 √{3 π ρ / 2 } (6 ln ⁡ρ +2 ln ⁡[96 π ]-9 )/ (12 ln ⁡ρ +4 ln ⁡[96 π ]-17 ) (R+1 ) 2/ (R-1 ) 2.

Bubble suspension rheology and implications for conduit flow

NASA Astrophysics Data System (ADS)

Llewellin, E. W.; Manga, M.

2005-05-01

Bubbles are ubiquitous in magma during eruption and influence the rheology of the suspension. Despite this, bubble-suspension rheology is routinely ignored in conduit-flow and eruption models, potentially impairing accuracy and resulting in the loss of important phenomenological richness. The omission is due, in part, to a historical confusion in the literature concerning the effect of bubbles on the rheology of a liquid. This confusion has now been largely resolved and recently published studies have identified two viscous regimes: in regime 1, the viscosity of the two-phase (magma-gas) suspension increases as gas volume fraction ϕ increases; in regime 2, the viscosity of the suspension decreases as ϕ increases. The viscous regime for a deforming bubble suspension can be determined by calculating two dimensionless numbers, the capillary number Ca and the dynamic capillary number Cd. We provide a didactic explanation of how to include the effect of bubble-suspension rheology in continuum, conduit-flow models. Bubble-suspension rheology is reviewed and a practical rheological model is presented, followed by an algorithmic, step-by-step guide to including the rheological model in conduit-flow models. Preliminary results from conduit-flow models which have implemented the model presented are discussed and it is concluded that the effect of bubbles on magma rheology may be important in nature and results in a decrease of at least 800 m in calculated fragmentation-depth and an increase of between 40% and 250% in calculated eruption-rate compared with the assumption of Newtonian rheology.

Regulation of store-operated Ca{sup 2+} entry activity by cell cycle dependent up-regulation of Orai2 in brain capillary endothelial cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kito, Hiroaki; Department of Pharmacology, Division of Pathological Sciences, Kyoto Pharmaceutical University, Kyoto; Yamamura, Hisao

2015-04-10

Store-operated Ca{sup 2+} entry (SOCE) via Orai1 and STIM1 complex is supposed to have obligatory roles in the regulation of cellular functions of vascular endothelial cells, while little is known about the contribution of Orai2. Quantitative PCR and Western blot analyses indicated the expression of Orai2 and STIM2, in addition to Orai1 and STIM1 in bovine brain capillary endothelial cell line, t-BBEC117. During the exponential growth of t-BBEC117, the knockdown of Orai1 and STIM1 significantly reduced the SOCE activity, whereas Orai2 and STIM2 siRNAs had no effect. To examine whether endogenous SOCE activity contributes to the regulation of cell cyclemore » progression, t-BBEC117 were synchronized using double thymidine blockage. At the G2/M phase, Ca{sup 2+} influx via SOCE was decreased and Orai2 expression was increased compared to the G0/G1 phase. When Orai2 was knocked down at the G2/M phase, the decrease in SOCE was removed, and cell proliferation was partly attenuated. Taken together, Orai1 significantly contributes to cell proliferation via the functional expression, which is presumably independent of the cell cycle phases. In construct, Orai2 is specifically up-regulated during the G2/M phase, negatively modulates the SOCE activity, and may contribute to the regulation of cell cycle progression in brain capillary endothelial cells. - Highlights: • Orai1 is essential for SOCE activity in brain capillary endothelial cells (BCECs). • Cell cycle independent expression of Orai1 regulated SOCE and cell proliferation. • Orai2 was up-regulated only at G2/M phase and this consequently reduced SOCE. • Orai2 as well as Orai1 is a key player controlling SOCE and proliferation in BCECs.« less

Serum proteins by capillary zone electrophoresis: approaches to the definition of reference values.

PubMed

Petrini, C; Alessio, M G; Scapellato, L; Brambilla, S; Franzini, C

1999-10-01

The Paragon CZE 2000 (Beckman Analytical, Milan, Italy) is an automatic dedicated capillary zone electrophoresis (CZE) system, producing a five-zone serum protein pattern with quantitative estimation of the zones. With the view of substituting this instrument for two previously used serum protein electrophoresis techniques, we planned to produce reference values for the "new" systems leading to compatible interpretation of the results. High resolution cellulose acetate electrophoresis with visual inspection and descriptive reporting (HR-CAE) and five-zone cellulose acetate electrophoresis with densitometry (CAE-D) were the previously used techniques. Serum samples (n = 167) giving "normal pattern" with HR-CAE were assayed with the CZE system, and the results were statistically assessed to yield 0.95 reference intervals. One thousand normal and pathological serum samples were then assayed with the CAE-D and the CZE techniques, and the regression equations of the CAE-D values over the CZE values for the five zones were used to transform the CAE-D reference limits into the CZE reference limits. The two sets of reference values thereby produced were in good agreement with each other and also with reference values previously reported for the CZE system. Thus, reference values for the CZE techniques permit interpretation of results coherent with the previously used techniques and reporting modes.

Deformable micro torque swimmer

NASA Astrophysics Data System (ADS)

Ishikawa, Takuji; Tanaka, Tomoyuki; Omori, Toshihiro; Imai, Yohsuke

2015-11-01

We investigated the deformation of a ciliate swimming freely in a fluid otherwise at rest. The cell body was modeled as a capsule with a hyper elastic membrane enclosing Newtonian fluid. Thrust forces due to the ciliary beat were modeled as torques distributed above the cell body. Effects of the membrane elasticity, the aspect ratio of cell's reference shape and the density difference between the cell and the surrounding fluid were investigated. The results showed that the cell deformed like heart shape when Capillary number (Ca) was sufficiently large, and the swimming velocity decreased as Ca was increased. The gravity effect on the membrane tension suggested that the upwards and downwards swimming velocities of Paramecium might be reglated by the calcium ion channels distributed locally around the anterior end. Moreover, the gravity induced deformation made a cell directed vertically downwards, which resulted in a positive geotaxis like behavior with physical origin. These results are important to understand physiology of ciliate's biological responses to mechanical stimuli.

Oriented shift and inverse of the daughter droplet due to the asymmetry of grand-daughter droplets of multiple emulsions in a symmetric flow field

NASA Astrophysics Data System (ADS)

Wang, Jingtao; Wang, Xiaoyong; Tai, Mo; Guan, Jing

2016-01-01

The rheological behaviors of multiple emulsions with an asymmetric internal structure in its third layer (grand-daughter droplets) under a modest extensional flow are investigated in this paper. The asymmetric structure will lead to the asymmetric circulation and pressure distribution inside the globule and eventually result in the oriented shift of its daughter droplet (in the second layer). The shift direction is affected not only by the structural asymmetry parameter As but also by some flow features including the capillary number Ca and viscosity ratio λ. Changes of these factors might cause the reverse of the shift direction, which are shown in three phase diagrams as a function of As, Ca, and λ. As the oriented shift of the daughter droplet would cause the oriented breakup of the multiple-emulsion globule, this phenomenon could be applied for the controlled release of the globule insertion by a hydrodynamic approach.

Visualization of surfactant enhanced NAPL mobilization and solubilization in a two-dimensional micromodel

DOE Office of Scientific and Technical Information (OSTI.GOV)

ZHONG,LIRONG; MAYER,ALEX; GLASS JR.,ROBERT J.

Surfactant-enhanced aquifer remediation is an emerging technology for aquifers contaminated with nonaqueous phase liquids (NAPLs). A two-dimensional micromodel and image capture system were applied to observe NAPL mobilization and solubilization phenomena. In each experiment, a common residual NAPL field was established, followed by a series of mobilization and solubilization experiments. Mobilization floods included pure water floods with variable flow rates and surfactant floods with variations in surfactant formulations. At relatively low capillary numbers (N{sub ca}<10{sup {minus}3}), the surfactant mobilization floods resulted in higher NAPL saturations than for the pure water flood, for similar N{sub ca}.These differences in macroscopic saturations aremore » explained by differences in micro-scale mobilization processes. Solubilization of the residual NAPL remaining after the mobilization stage was dominated by the formation of dissolution fingers, which produced nonequilibrium NAPL solubilization. A macroemulsion phase also as observed to form spontaneously and persist during the solubilization stage of the experiments.« less

Regulation of store-operated Ca2+ entry activity by cell cycle dependent up-regulation of Orai2 in brain capillary endothelial cells.

PubMed

Kito, Hiroaki; Yamamura, Hisao; Suzuki, Yoshiaki; Yamamura, Hideto; Ohya, Susumu; Asai, Kiyofumi; Imaizumi, Yuji

2015-04-10

Store-operated Ca(2+) entry (SOCE) via Orai1 and STIM1 complex is supposed to have obligatory roles in the regulation of cellular functions of vascular endothelial cells, while little is known about the contribution of Orai2. Quantitative PCR and Western blot analyses indicated the expression of Orai2 and STIM2, in addition to Orai1 and STIM1 in bovine brain capillary endothelial cell line, t-BBEC117. During the exponential growth of t-BBEC117, the knockdown of Orai1 and STIM1 significantly reduced the SOCE activity, whereas Orai2 and STIM2 siRNAs had no effect. To examine whether endogenous SOCE activity contributes to the regulation of cell cycle progression, t-BBEC117 were synchronized using double thymidine blockage. At the G2/M phase, Ca(2+) influx via SOCE was decreased and Orai2 expression was increased compared to the G0/G1 phase. When Orai2 was knocked down at the G2/M phase, the decrease in SOCE was removed, and cell proliferation was partly attenuated. Taken together, Orai1 significantly contributes to cell proliferation via the functional expression, which is presumably independent of the cell cycle phases. In construct, Orai2 is specifically up-regulated during the G2/M phase, negatively modulates the SOCE activity, and may contribute to the regulation of cell cycle progression in brain capillary endothelial cells. Copyright © 2015 Elsevier Inc. All rights reserved.

Lattice Boltzmann simulation of immiscible fluid displacement in porous media: Homogeneous versus heterogeneous pore network

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Haihu, E-mail: haihu.liu@mail.xjtu.edu.cn; James Weir Fluids Laboratory, Department of Mechanical and Aerospace Engineering, University of Strathclyde, Glasgow G1 1XJ; Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801

Injection of anthropogenic carbon dioxide (CO{sub 2}) into geological formations is a promising approach to reduce greenhouse gas emissions into the atmosphere. Predicting the amount of CO{sub 2} that can be captured and its long-term storage stability in subsurface requires a fundamental understanding of multiphase displacement phenomena at the pore scale. In this paper, the lattice Boltzmann method is employed to simulate the immiscible displacement of a wetting fluid by a non-wetting one in two microfluidic flow cells, one with a homogeneous pore network and the other with a randomly heterogeneous pore network. We have identified three different displacement patterns,more » namely, stable displacement, capillary fingering, and viscous fingering, all of which are strongly dependent upon the capillary number (Ca), viscosity ratio (M), and the media heterogeneity. The non-wetting fluid saturation (S{sub nw}) is found to increase nearly linearly with logCa for each constant M. Increasing M (viscosity ratio of non-wetting fluid to wetting fluid) or decreasing the media heterogeneity can enhance the stability of the displacement process, resulting in an increase in S{sub nw}. In either pore networks, the specific interfacial length is linearly proportional to S{sub nw} during drainage with equal proportionality constant for all cases excluding those revealing considerable viscous fingering. Our numerical results confirm the previous experimental finding that the steady state specific interfacial length exhibits a linear dependence on S{sub nw} for either favorable (M ≥ 1) or unfavorable (M < 1) displacement, and the slope is slightly higher for the unfavorable displacement.« less

A con-focal setup for micro-XRF experiments using diamond anvil cells

NASA Astrophysics Data System (ADS)

Wilke, Max; Rickers, Karen; Vincze, Laszlo; Schmidt, Christian; Borchert, Manuela; Pascarelli, Sakura

2010-05-01

In this contribution we introduce an experimental setup to perform con-focal micro X-ray fluorescence measurements in situ in samples at high temperatures and pressures in diamond anvil cells (DAC) (e.g. Schmidt et al. 2007). The con-focal arrangement is used to suppress the background in X-ray fluorescence (XRF) spectra that stems from elastic and inelastic scattering of the diamond anvils. The setup is based on a focusing optic in the incident beam that reaches a spot of 5-10 μm and a focusing poly-capillary in front of an energy-dispersive solid-state detector. The detector poly-capillary is designed to work at a very long working distance of 50 mm in order to collect the radiation from the center of the DAC at 90° to the incident beam. The probing volume is defined by the two foci and has a size of ca. 300 μm at 8 keV and 150 μm at 19 keV as measured by scans through thin metal foils. Comparison of XRF spectra acquired with a usual detector collimator and spectra recorded with the detector capillary shows a strong suppression of XRF signal generated outside the probed volume, i.e. XRF from the gasket material and signal from elastic and Compton scattering by the diamond anvils. The ratio of the Zr K-alpha fluorescence peak to the peak of the Compton scattering changes from 0.5 (collimator) to 1.26 (detector capillary) for a ca. 1000 ppm Zr standard solution and an incident beam energy of 20 keV. For a standard solution containing ca. 1000 ppm Hf, the ratio of the L-alpha to the Compton signal increases to 6 using the detector capillary and an incident beam energy of 9.7 keV. Thus, the con-focal setup substantially improves the fluorescence to background ratio. This will result in higher sensitivities for dilute elements in the sample chamber of the DAC. Furthermore, the possibilities of interference of the sample's signal with signal from the sample environment are greatly reduced. In a broader sense, the setup can also be applied to other confined samples that require long working distances. Schmidt et al. (2007) Lithos 95, 87-102

Liquid film drag out in the presence of molecular forces

NASA Astrophysics Data System (ADS)

Schmidhalter, I.; Cerro, R. L.; Giavedoni, M. D.; Saita, F. A.

2013-03-01

From a practical as well as a conceptual point of view, one of the most interesting problems of physicochemical hydrodynamics is the drag out of a liquid film by a moving solid out of a pool of liquid. The basic problem, sometimes denoted the Landau-Levich problem [L. Landau and B. Levich, "Dragging of a liquid by a moving plate," Acta Physicochim. USSR 17, 42-54 (1942)], involves an interesting blend of capillary and viscous forces plus a matching of the static solution for capillary rise with a numerical solution of the film evolution equation, neglecting gravity, on the downstream region of the flow field. The original solution describes experimental data for a wide range of Capillary numbers but fails to match results for large and very small Capillary numbers. Molecular level forces are introduced to create an augmented version of the film evolution equation to show the effect of van der Waals forces at the lower range of Capillary numbers. A closed form solution for static capillary rise, including molecular forces, was matched with a numerical solution of the augmented film evolution equation in the dynamic meniscus region. Molecular forces do not sensibly modify the static capillary rise region, since film thicknesses are larger than the range of influence of van der Waals forces, but are determinant in shaping the downstream dynamic meniscus of the very thin liquid films. As expected, a quantitatively different level of disjoining pressure for different values of molecular constants remains in the very thin liquid film far downstream. Computational results for a wide range of Capillary numbers and Hamaker constants show a clear transition towards a region where the film thickness becomes independent of the coating speed.

Microfluidic devices connected to fused-silica capillaries with minimal dead volume.

PubMed

Bings, N H; Wang, C; Skinner, C D; Colyer, C L; Thibault, P; Harrison, D J

1999-08-01

Fused-silica capillaries have been connected to microfluidic devices for capillary electrophoresis by drilling into the edge of the device using 200-μm tungsten carbide drills. The standard pointed drill bits create a hole with a conical-shaped bottom that leads to a geometric dead volume of 0.7 nL at the junction, and significant band broadening when used with 0.2-nL sample plugs. The plate numbers obtained on the fused-silica capillary connected to the chip were about 16-25% of the predicted numbers. The conical area was removed with a flat-tipped drill bit and the band broadening was substantially eliminated (on average 98% of the predicted plate numbers were observed). All measurements were made while the device was operating with an electrospray from the end of the capillary. The effective dead volume of the flat-bottom connection is minimal and allows microfluidic devices to be connected to a wide variety of external detectors.

Quantitative nailfold capillaroscopy findings in a population with connective tissue disease and in normal healthy controls.

PubMed Central

Kabasakal, Y; Elvins, D M; Ring, E F; McHugh, N J

1996-01-01

OBJECTIVE: To describe and quantify the morphological characteristics of nailfold capillaries that distinguish different forms of connective tissue disease from healthy controls. METHODS: A CCD video microscope with fibreoptic illumination and PC based image processing was used to visualise nailfold capillaries and to quantify findings in 23 patients with systemic sclerosis (SSc), 22 patients with systemic lupus erythematosus (SLE), 21 patients with undifferentiated connective tissue disease (UCTD), and 38 healthy controls. RESULTS: Capillary density was reduced in SSc (5.2 (SD 1.3) capillaries/mm) compared with other patient groups and controls. The average number of enlarged capillaries/finger was high in all disease groups (5.5-6.6) compared with controls (2). However, giant capillaries were most frequent in SSc (43%) and were not present in controls. Mild and moderate avascular areas were present in all groups (35%-68%), but severe avascularity was most frequent in SSc (44%) compared with other patients (18%-19%) and controls (0%). The greatest frequency of extensive haemorrhage was in SSc (35%). CONCLUSIONS: There is a range of abnormal capillary findings in patients with connective tissue disease and healthy controls. However, certain abnormalities such as a reduced number of capillaries, severe avascularity, giant capillaries, and haemorrhage are most commonly associated with SSc. Videomicroscopy with image processing offers many technical advantages that can be exploited in further studies of nailfold capillaries. Images PMID:8774177

[The diagnostic significance of nailfold video-capillaroscopy in systemic sclerosis].

PubMed

Li, Lin-Guang; Zhang, Jiang-Lin; Liu, Xiu-Hua; Huang, Feng

2012-05-01

To observe nailfold capillary changes in a cohort of connective tissue disease (CTD) with Raynaud's phenomenon (RP) and to explore the diagnostic value of nailfold video-capillaroscopy (NVC) in systemic sclerosis (SSc). Sixty CTD patients with RP divided into SSc group (n = 36) and non-SSc group (n = 24) were referred to an experienced operator for NVC. The patients had decreased capillary loops in SSc group with the capillary diameter more enlarged in SSc group than non-SSc group. The number of patients in SSc group with giant capillaries was 14, while 3 in non-SSc group. There were 23 patients with haemorrhages in SSc group and 9 in non-SSc group. The number of patients with severe effusion was 15 in SSc group, while 2 in non-SSc group. By using the ROC curves, indexes with AUC at least 0.7 of the input capillary diameter, the output capillary diameter, the middle capillary diameter, blood color and effusion for the diagnostic cutoff points were 18.5 µm, 24.5 µm, 19.5µm, deep red and severe effusion. With at least 2 out of the top 3 indexes, the diagnostic sensitivity and specificity of SSc were higher. CTD Patients with RP of SSc have less capillary loops, more enlarged capillaries, more giant capillaries, more severe effusion and more haemorrhages than non-SSc patients. The characteristics of nailfold capillary changes in SSc patients with RP can be helpful for the diagnosis and the differential diagnosis of SSc.

Supplementation with complex milk lipids during brain development promotes neuroplasticity without altering myelination or vascular density

PubMed Central

Guillermo, Rosamond B.; Yang, Panzao; Vickers, Mark H.; McJarrow, Paul; Guan, Jian

2015-01-01

Background Supplementation with complex milk lipids (CML) during postnatal brain development has been shown to improve spatial reference learning in rats. Objective The current study examined histo-biological changes in the brain following CML supplementation and their relationship to the observed improvements in memory. Design The study used the brain tissues from the rats (male Wistar, 80 days of age) after supplementing with either CML or vehicle during postnatal day 10–80. Immunohistochemical staining of synaptophysin, glutamate receptor-1, myelin basic protein, isolectin B-4, and glial fibrillary acidic protein was performed. The average area and the density of the staining and the numbers of astrocytes and capillaries were assessed and analysed. Results Compared with control rats, CML supplementation increased the average area of synaptophysin staining and the number of GFAP astrocytes in the CA3 sub-region of the hippocampus (p<0.01), but not in the CA4 sub-region. The supplementation also led to an increase in dopamine output in the striatum that was related to nigral dopamine expression (p<0.05), but did not alter glutamate receptors, myelination or vascular density. Conclusion CML supplementation may enhance neuroplasticity in the CA3 sub-regions of the hippocampus. The brain regions-specific increase of astrocyte may indicate a supporting role for GFAP in synaptic plasticity. CML supplementation did not associate with postnatal white matter development or vascular remodelling. PMID:25818888

Contribution of capillary electrophoresis to an integrated vision of humic substances size and charge characterizations

DOE Office of Scientific and Technical Information (OSTI.GOV)

D'Orlye, Fanny; Reiller, Pascal E.

2014-02-15

The physicochemical properties of three different humic substances (HS) are probed using capillary zone electrophoresis in alkaline carbonate buffers, pH 10. Special attention is drawn to the impact of the electrolyte ionic strength and counter-ion nature, chosen within the alkali-metal series, on HS electrophoretic mobility. Taylor-Aris dispersion analysis provides insights into the hydrodynamic radius (R-H) distributions of HS. The smallest characterized entities are of nano-metric dimensions, showing neither ionic strength- nor alkali-metal-induced aggregation. These results are compared with the entities evidenced in dynamic light scattering measurements, the size of which is two order of magnitude higher, ca. 100 nm. Themore » extended Onsager model provides a reasonable description of measured electrophoretic mobilities in the ionic strength range 1-50 mM, thus allowing the estimation of limiting mobilities and ionic charge numbers for the different HS samples. An unexpected HS electrophoretic mobility increase (in absolute value) is observed in the order Li{sup +} ≤ Na{sup +} ≤ K{sup +} ≤ Cs{sup +} and discussed either in terms of retarding forces or in terms of ion-ion interactions. (authors)« less

Capillary cerebral amyloid angiopathy in Alzheimer's disease: association with allocortical/hippocampal microinfarcts and cognitive decline.

PubMed

Hecht, Moritz; Krämer, Lara Maria; von Arnim, Christine A F; Otto, Markus; Thal, Dietmar Rudolf

2018-05-01

Cerebral amyloid angiopathy (CAA) is caused by the deposition of the amyloid β-protein (Aβ) in the wall of cerebral and leptomeningeal blood vessels and is related to Alzheimer's disease (AD). Capillary Aβ deposition is observed in a subset of CAA cases and represents a distinct type of CAA named capillary CAA or CAA type 1. This type of CAA is strongly associated with the presence of the apolipoprotein E ε4 allele. CAA type 1-associated AD cases often exhibit a more severe Aβ plaque pathology but less widespread neurofibrillary tangle (NFT) pathology. The objective of this study was to analyze whether capillary CAA and its effects on cerebral blood flow have an impact on dementia. To address this objective, we performed neuropathological evaluation of 284 autopsy cases of demented and non-demented individuals. We assessed the presence of CAA and its subtypes as well as for that of hemorrhages and infarcts. Capillary CAA and CAA severity were associated with allocortical microinfarcts, comprising the CA1 region of the hippocampus. Allocortical microinfarcts, capillary CAA and CAA severity were, thereby, associated with cognitive decline. In conclusion, allocortical microinfarcts, CAA severity, and the capillary type of CAA were associated with one another and with the development of cognitive decline. Thus, AD cases with CAA type 1 (capillary CAA) appear to develop dementia symptoms not only due to AD-related Aβ plaque and NFT pathology but also due to hippocampal microinfarcts that are associated with CAA type 1 and CAA severity, and that damage a brain region important for memory function.

Effects of polymer-nanoparticle interactions on the viscosity of unentangled polymers under extreme nanoconfinement during capillary rise infiltration.

PubMed

Hor, Jyo Lyn; Wang, Haonan; Fakhraai, Zahra; Lee, Daeyeon

2018-03-28

We explore the effect of confinement and polymer-nanoparticle interactions on the viscosity of unentangled polymers undergoing capillary rise infiltration (CaRI) in dense packings of nanoparticles. In CaRI, a polymer is thermally induced to wick into the dense packings of nanoparticles, leading to the formation of polymer-infiltrated nanoparticle films, a new class of thin film nanocomposites with extremely high concentrations of nanoparticles. To understand the effect of this extreme nanoconfinement, as well as polymer-nanoparticle interactions on the polymer viscosity in CaRI films, we use two polymers that are known to have very different interactions with SiO2 nanoparticles. Using in situ spectroscopic ellipsometry, we monitor the polymer infiltration process, from which we infer the polymer viscosity based on the Lucas-Washburn model. Our results suggest that physical confinement increases the viscosity by approximately two orders of magnitude. Furthermore, confinement also increases the glass transition temperature of both polymers. Thus, under extreme nanoconfinement, the physical confinement has a more significant impact than the polymer-nanoparticle interactions on the viscosity of unentangled polymers, measured through infiltration dynamics, as well as the glass transition temperature. These findings will provide fundamental frameworks for designing processes to enable the fabrication of CaRI nanocomposite films with a wide range of nanoparticles and polymers.

Up-regulation of K{sub ir}2.1 by ER stress facilitates cell death of brain capillary endothelial cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kito, Hiroaki; Yamazaki, Daiju; Department of Biological Chemistry, Kyoto University, Graduate School of Pharmaceutical Sciences, Kyoto

Highlights: {yields} We found that application of endoplasmic reticulum (ER) stress with tunicamycin to brain capillary endothelial cells (BCECs) induced cell death. {yields} The ER stress facilitated the expression of inward rectifier K{sup +} channel (K{sub ir}2.1) and induced sustained membrane hyperpolarization. {yields} The membrane hyperpolarization induced sustained Ca{sup 2+} entry through voltage-independent nonspecific cation channels and consequently facilitated cell death. {yields} The K{sub ir}2.1 up-regulation by ER stress is, at least in part, responsible for cell death of BCECs under pathological conditions. -- Abstract: Brain capillary endothelial cells (BCECs) form blood brain barrier (BBB) to maintain brain homeostasis. Cellmore » turnover of BCECs by the balance of cell proliferation and cell death is critical for maintaining the integrity of BBB. Here we found that stimuli with tunicamycin, endoplasmic reticulum (ER) stress inducer, up-regulated inward rectifier K{sup +} channel (K{sub ir}2.1) and facilitated cell death in t-BBEC117, a cell line derived from bovine BCECs. The activation of K{sub ir} channels contributed to the establishment of deeply negative resting membrane potential in t-BBEC117. The deep resting membrane potential increased the resting intracellular Ca{sup 2+} concentration due to Ca{sup 2+} influx through non-selective cation channels and thereby partly but significantly regulated cell death in t-BBEC117. The present results suggest that the up-regulation of K{sub ir}2.1 is, at least in part, responsible for cell death/cell turnover of BCECs induced by a variety of cellular stresses, particularly ER stress, under pathological conditions.« less

Rapid and Simple Capillary-Rise/Vanishing Interfacial Tension Method To Determine Crude Oil Minimum Miscibility Pressure: Pure and Mixed CO 2, Methane, and Ethane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hawthorne, Steven B.; Miller, David J.; Jin, Lu

Here, we report a simplification of the capillary-rise/vanishing interfacial tension (IFT) method to measure minimum miscibility pressure (MMP) based on only requiring knowledge of when the interfacial tension approaches zero. Simply measuring the height of the crude oil in a capillary at several pressures from ambient to near the MMP pressure and extrapolating the oil height versus pressure plot to zero oil height yields the MMP without the need of the additional instrumentation and labor required to perform actual IFT measurements. A total of 2-4 MMP values can be determined per day with only one experimental apparatus, and the methodmore » greatly reduces the initial cost and complexity of the required instrumentation. The use of three capillaries having different inner diameters allows for triplicate determinations of MMP from each experiment. Because the actual MMP pressure need not be reached during the experiment, MMP values that exceed the pressure ratings of the equipment can be reasonably estimated (e.g., MMPs using pure nitrogen). The method was used to determine the MMP pressure for crude oil samples from a conventional Muddy Formation reservoir in the Powder River Basin [American Petroleum Institute (API) gravity of 35.8°] and an unconventional Bakken Formation reservoir in the Williston Basin (API gravity of 38.7°). The method is reproducible [typically <4% relative standard deviation (RSD)], and the method gave good agreement for a “live” Bakken oil with the results from a slim tube test of a commercial laboratory. Approximately 80 MMP values were measured using pure CO 2, methane, and ethane as well as 0-100% mole ratios of methane/CO 2 and methane/ethane. For both oil samples, ethane MMPs were ca. one-half those with CO 2, while methane MMPs were ca. double or triple those with CO 2. MMPs with mixed methane/CO 2 showed a linear increase with mole percent methane for both crude oils, while both oils showed an exponential increase in MMP with mole percent methane in ethane, with a little increase in MMP until ca. 20 mol % methane in ethane.« less

Rapid and Simple Capillary-Rise/Vanishing Interfacial Tension Method To Determine Crude Oil Minimum Miscibility Pressure: Pure and Mixed CO 2, Methane, and Ethane

DOE PAGES

Hawthorne, Steven B.; Miller, David J.; Jin, Lu; ...

2016-07-10

Here, we report a simplification of the capillary-rise/vanishing interfacial tension (IFT) method to measure minimum miscibility pressure (MMP) based on only requiring knowledge of when the interfacial tension approaches zero. Simply measuring the height of the crude oil in a capillary at several pressures from ambient to near the MMP pressure and extrapolating the oil height versus pressure plot to zero oil height yields the MMP without the need of the additional instrumentation and labor required to perform actual IFT measurements. A total of 2-4 MMP values can be determined per day with only one experimental apparatus, and the methodmore » greatly reduces the initial cost and complexity of the required instrumentation. The use of three capillaries having different inner diameters allows for triplicate determinations of MMP from each experiment. Because the actual MMP pressure need not be reached during the experiment, MMP values that exceed the pressure ratings of the equipment can be reasonably estimated (e.g., MMPs using pure nitrogen). The method was used to determine the MMP pressure for crude oil samples from a conventional Muddy Formation reservoir in the Powder River Basin [American Petroleum Institute (API) gravity of 35.8°] and an unconventional Bakken Formation reservoir in the Williston Basin (API gravity of 38.7°). The method is reproducible [typically <4% relative standard deviation (RSD)], and the method gave good agreement for a “live” Bakken oil with the results from a slim tube test of a commercial laboratory. Approximately 80 MMP values were measured using pure CO 2, methane, and ethane as well as 0-100% mole ratios of methane/CO 2 and methane/ethane. For both oil samples, ethane MMPs were ca. one-half those with CO 2, while methane MMPs were ca. double or triple those with CO 2. MMPs with mixed methane/CO 2 showed a linear increase with mole percent methane for both crude oils, while both oils showed an exponential increase in MMP with mole percent methane in ethane, with a little increase in MMP until ca. 20 mol % methane in ethane.« less

Highly efficient monolithic silica capillary columns modified with poly(acrylic acid) for hydrophilic interaction chromatography.

PubMed

Horie, Kanta; Ikegami, Tohru; Hosoya, Ken; Saad, Nabil; Fiehn, Oliver; Tanaka, Nobuo

2007-09-14

Monolithic silica capillary columns for hydrophilic interaction liquid chromatography (HILIC) were prepared by on-column polymerization of acrylic acid on monolithic silica in a fused silica capillary modified with anchor groups. The products maintained the high permeability (K=5 x 10(-14)m(2)) and provided a plate height (H) of less than 10 microm at optimum linear velocity (u) and H below 20 microm at u=6mm/s for polar solutes including nucleosides and carbohydrates. The HILIC mode monolithic silica capillary column was able to produce 10000 theoretical plates (N) with column dead time (t(0)) of 20s at a pressure drop of 20 MPa or lower. The total performance was much higher than conventional particle-packed HILIC columns currently available. The gradient separations of peptides by a capillary LC-electrospray mass spectrometry system resulted in very different retention selectivity between reversed-phase mode separations and the HILIC mode separations with a peak capacity of ca. 100 in a 10 min gradient time in either mode. The high performance observed with the monolithic silica capillary column modified with poly(acrylic acid) suggests that the HILIC mode can be an alternative to the reversed-phase mode for a wide range of compounds, especially for those of high polarity in isocratic as well as gradient elution.

Wettability control on fluid-fluid displacements in patterned microfluidics and porous media

NASA Astrophysics Data System (ADS)

Juanes, Ruben; Trojer, Mathias; Zhao, Benzhong

2014-11-01

While it is well known that the wetting properties are critical in two-phase flows in porous media, the effect of wettability on fluid displacement continues to challenge our microscopic and macroscopic descriptions. Here we study this problem experimentally, starting with the classic experiment of two-phase flow in a capillary tube. We image the shape of the meniscus and measure the associated capillary pressure for a wide range of capillary numbers. We synthesize new observations on the dependence of the dynamic capillary pressure on wetting properties (contact angle) and flow conditions (viscosity contrast and capillary number). We then conduct experiments on a planar microfluidic device patterned with vertical posts. We track the evolution of the fluid-fluid interface and elucidate the impact of wetting on the cooperative nature of fluid displacement during pore invasion events. We use the insights gained from the capillary tube and patterned microfluidics experiments to elucidate the effect of wetting properties on viscous fingering and capillary fingering in a Hele-Shaw cell filled with glass beads, where we observe a contact-angle-dependent stabilizing behavior for the emerging flow instabilities, as the system transitions from drainage to imbibition.

Investigation of the Dynamic Contact Angle Using a Direct Numerical Simulation Method.

PubMed

Zhu, Guangpu; Yao, Jun; Zhang, Lei; Sun, Hai; Li, Aifen; Shams, Bilal

2016-11-15

A large amount of residual oil, which exists as isolated oil slugs, remains trapped in reservoirs after water flooding. Numerous numerical studies are performed to investigate the fundamental flow mechanism of oil slugs to improve flooding efficiency. Dynamic contact angle models are usually introduced to simulate an accurate contact angle and meniscus displacement of oil slugs under a high capillary number. Nevertheless, in the oil slug flow simulation process, it is unnecessary to introduce the dynamic contact angle model because of a negligible change in the meniscus displacement after using the dynamic contact angle model when the capillary number is small. Therefore, a critical capillary number should be introduced to judge whether the dynamic contact model should be incorporated into simulations. In this study, a direct numerical simulation method is employed to simulate the oil slug flow in a capillary tube at the pore scale. The position of the interface between water and the oil slug is determined using the phase-field method. The capacity and accuracy of the model are validated using a classical benchmark: a dynamic capillary filling process. Then, different dynamic contact angle models and the factors that affect the dynamic contact angle are analyzed. The meniscus displacements of oil slugs with a dynamic contact angle and a static contact angle (SCA) are obtained during simulations, and the relative error between them is calculated automatically. The relative error limit has been defined to be 5%, beyond which the dynamic contact angle model needs to be incorporated into the simulation to approach the realistic displacement. Thus, the desired critical capillary number can be determined. A three-dimensional universal chart of critical capillary number, which functions as static contact angle and viscosity ratio, is given to provide a guideline for oil slug simulation. Also, a fitting formula is presented for ease of use.

Muscle fiber type characteristics in females with chronic obstructive pulmonary disease. A preliminary study.

PubMed

Green, Howard J; Burnett, M E; D'Arsigny, C; Iqbal, S; Ouyang, J; Webb, K A; O'Donnell, D E

2009-02-01

Chronic obstructive pulmonary disease (COPD) is known to elicit intrinsic abnormalities in male skeletal muscle. However, it is unclear to what extent these changes occur in women and whether they are fiber-type specific. We investigated fiber-type specific differences in selected histochemical properties in muscle obtained from women with moderate to severe COPD compared to healthy control (CON) women. Tissue was obtained from the vastus lateralis in five COPD patients (age 66.9 +/- 2.6 years; FEV1 = 43 +/- 7%) and eight CON (age 68 +/- 4.9 years; FEV1 = 113 +/- 4.2%). Compared to CON, the distribution (30.6 +/- 5.2 vs. 57.9 +/- 4.6%) and cross sectional area of type I (CSA, 5660 +/- 329 vs. 3586 +/- 257 microm2) and type IIA (2770 +/- 302 vs. 2099 +/- 206 microm2) were lower (P < 0.05) and higher (P < 0.05), respectively, in COPD. Disease state did not alter either the distribution or CSA of the IIA, IIAX or type X subtypes. Although differences were found between fiber types in the number of capillary contacts (n) (I > IIAX, IIX; IIA > IIX) and the capillaries per CSA (microm210(-3)) (I < IIA, IIAX, IIX), no differences were found between CON and COPD. Succinic dehydrogenase activity and sarcoplasmic reticulum (SR) Ca2+-ATPase activity, measured photometrically (OD units), were higher (P < 0.05), and lower (P < 0.05), respectively, in type I compared to the type II fiber subtypes. These properties were not altered with COPD. COPD in females is accompanied by a higher percent of type II fibers, a larger CSA of type I and type IIA fibers, both of which occur in the absence of differences in oxidative potential and the potential for SR Ca2+-sequestration.

Droplets coalescence at microchannel intersection chambers with different shapes

NASA Astrophysics Data System (ADS)

Liu, Zhaomiao; Wang, Xiang; Cao, Rentuo; Pang, Yan

2016-11-01

The influence of microchannel intersection chamber shape on droplets coalescence process is investigated in this study. Three kinds of chamber shapes (half-round, triangle and camber) are designed to realize head-on droplets coalescence. The coalescence processes are visualized with high-speed camera system and the internal flow patterns are resolved with micro-PIV system. Experimental analyses on droplets coalescence position, coalescence time and the critical conditions are discussed. Both direct coalescence and late coalescence can be observed in the camber junction while only the late coalescence is present for the half-round and the triangle junction. The critical capillary number Ca* varies for different working systems or intersection shapes. Ca* in the camber junction is larger than that in the other two junctions for each working system and it decreases with the increase of the viscosity ratios for each intersection shape. Moreover, the characteristics of the velocity fields for different coalescence cases are analyzed for in-depth understanding of the process. The authors do appreciate the financial support of No.11572013 of National Nature Scicence Funding of China.

Micromachined chemical jet dispenser

DOEpatents

Swierkowski, S.P.

1999-03-02

A dispenser is disclosed for chemical fluid samples that need to be precisely ejected in size, location, and time. The dispenser is a micro-electro-mechanical systems (MEMS) device fabricated in a bonded silicon wafer and a substrate, such as glass or silicon, using integrated circuit-like fabrication technology which is amenable to mass production. The dispensing is actuated by ultrasonic transducers that efficiently produce a pressure wave in capillaries that contain the chemicals. The 10-200 {micro}m diameter capillaries can be arranged to focus in one spot or may be arranged in a larger dense linear array (ca. 200 capillaries). The dispenser is analogous to some ink jet print heads for computer printers but the fluid is not heated, thus not damaging certain samples. Major applications are in biological sample handling and in analytical chemical procedures such as environmental sample analysis, medical lab analysis, or molecular biology chemistry experiments. 4 figs.

Nailfold capillaroscopy abnormalities correlate with cutaneous and visceral involvement in systemic sclerosis patients.

PubMed

Sato, Lucy T; Kayser, Cristiane; Andrade, Luís E C

2009-01-01

The aim of this study was to correlate quantitative and semiquantitative nailfold capillaroscopy (NFC) parameters with the extent of cutaneous and visceral involvement in systemic sclerosis (SSc) patients. The presence of clinical and serological alterations was evaluated retrospectively and correlated with NFC findings (number of capillary loops/mm, vascular deletion score and number of enlarged and giant capillary loops). For evaluation of disease extension five manifestations were analyzed: finger pad lesions, skin involvement, esophageal involvement, interstitial lung disease, and pulmonary hypertension. There were 105 NFC examinations in 92 patients, 13 of whom were evaluated at two different time points. Patients with diffuse cutaneous SSc had a higher vascular deletion score than patients with limited cutaneous SSc, sine scleroderma SSc, and overlap syndrome (1.67+/-0.91 vs 0.99+/-0.82; p=0.0005). Modified Rodnan's skin score correlated positively with capillary deletion, evaluated by the vascular deletion score and the number of capillary loops/mm (p<0.001 and p=0.012; respectively). Patients with three or more involved tracts presented lower number of capillary loops/mm (8.00+/-1.69 vs 9.23+/-1.31 capillary loops/mm; p=0.025) and a higher vascular deletion score (1.41+/-0.95 vs 0.73+/-0.76; p=0.027) when compared to patients with less than three affected tracts. Vascular deletion score was significantly higher in patients with anti-Scl-70 antibodies that in patients without anti-Scl-70 antibodies (p=0.02). NFC abnormalities correlated positively with the diffuse form of SSc, the degree of cutaneous involvement, the number of affected tracts, and the presence of anti-Scl-70 antibodies.

Compliance with dietary guidelines affects capillary recruitment in healthy middle-aged men and women.

PubMed

Govoni, Virginia; Sanders, Thomas A B; Reidlinger, Dianne P; Darzi, Julia; Berry, Sarah E E; Goff, Louise M; Seed, Paul T; Chowienczyk, Philip J; Hall, Wendy L

2017-04-01

Healthy microcirculation is important to maintain the health of tissues and organs, most notably the heart, kidney and retina. Single components of the diet such as salt, lipids and polyphenols may influence microcirculation, but the effects of dietary patterns that are consistent with current dietary guidelines are uncertain. It was hypothesized that compliance to UK dietary guidelines would have a favourable effect on skin capillary density/recruitment compared with a traditional British diet (control diet). A 12-week randomized controlled trial in men and women aged 40-70 years was used to test whether skin microcirculation, measured by skin video-capillaroscopy on the dorsum of the finger, influenced functional capillary density (number of capillaries perfused under basal conditions), structural capillary density (number of anatomical capillaries perfused during finger cuff inflation) and capillary recruitment (percentage difference between structural and functional capillary density). Microvascular measures were available for 137 subjects out of the 165 participants randomized to treatment. There was evidence of compliance to the dietary intervention, and participants randomized to follow dietary guidelines showed significant falls in resting supine systolic, diastolic and mean arterial pressure of 3.5, 2.6 and 2.9 mmHg compared to the control diet. There was no evidence of differences in capillary density, but capillary recruitment was 3.5 % (95 % CI 0.2, 6.9) greater (P = 0.04) on dietary guidelines compared with control. Adherence to dietary guidelines may help maintain a healthy microcirculation in middle-aged men and women. This study is registered at www.isrctn.com as ISRCTN92382106.

The elevation, slope, and curvature spectra of a wind roughened sea surface

NASA Technical Reports Server (NTRS)

Pierson, W. J., Jr.; Stacy, R. A.

1973-01-01

The elevation, slope and curvature spectra are defined as a function of wave number and depend on the friction velocity. There are five wave number ranges of definition called the gravity wave-gravity equilibrium range, the isotropic turbulence range, the connecting range due to Leykin Rosenberg, the capillary range, and the viscous cutoff range. The higher wave number ranges are strongly wind speed dependent, and there is no equilibrium (or saturated) capillary range, at least for winds up to 30 meters/sec. Some properties of the angular variation of the spectra are also found. For high wave numbers, especially in the capillary range, the results are shown to be consistent with the Rayleigh-Rice backscattering theory (Bragg scattering), and certain properties of the angular variation are deduced from backscatter measurements.

Capillary density: An important parameter in nailfold capillaroscopy.

PubMed

Emrani, Zahra; Karbalaie, Abdolamir; Fatemi, Alimohammad; Etehadtavakol, Mahnaz; Erlandsson, Björn-Erik

2017-01-01

Nailfold capillaroscopy is one of the various noninvasive bioengineering methods used to investigate skin microcirculation. It is an effective examination for assessing microvascular changes in the peripheral circulation; hence it has a significant role for the diagnosis of Systemic sclerosis with the classic changes of giant capillaries as well as the decline in capillary density with capillary dropout. The decline in capillary density is one of microangiopathic features existing in connective tissue disease. It is detectable with nailfold capillaroscopy. This parameter is assessed by applying quantitative measurement. In this article, we reviewed a common method for calculating the capillary density and the relation between the number of capillaries as well as the existence of digital ulcers, pulmonary arterial hypertension, autoantibodies, scleroderma patterns and different scoring system. Copyright © 2016 Elsevier Inc. All rights reserved.

Capillary spreading of contact line over a sinking sphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Seong Jin; Fezzaa, Kamel; An, Jim

The contact line dynamics over a sinking solid sphere are investigated in comparison with classical spreading theories. Experimentally, high-speed imaging systems with optical light or x-ray illumination are employed to accurately measure the spreading motion and dynamic contact angle of the contact line. Millimetric spheres are controlled to descend with a constant speed ranging from 7.3 × 10-5 to 0.79 m/s. We observed three different spreading stages over a sinking sphere, which depends on the contact line velocity and contact angle. These stages consistently showed the characteristics of capillarity-driven spreading as the contact line spreads faster with a higher contactmore » angle. The contact line velocity is observed to follow a classical capillary-viscous model at a high Ohnesorge number (> 0.02). For the cases with a relatively low Ohnesorge number (< 0.02), the contact line velocity is significantly lower than the speed predicted by the capillary-viscous balance. This indicates the existence of an additional opposing force (inertia) for a decreasing Ohnesorge number. The capillary-inertial balance is only observed at the very beginning of the capillary rise, in which the maximum velocity is independent of the sphere’s sinking speed. Additionally, we observed the linear relation between the contact line velocity and the sphere sinking speed during the second stage, which represents capillary adjustment by dynamic contact angle.« less

Mapping human brain capillary water lifetime: high‐resolution metabolic neuroimaging

PubMed Central

Li, Xin; Sammi, Manoj K.; Bourdette, Dennis N.; Neuwelt, Edward A.

2015-01-01

Shutter‐speed analysis of dynamic‐contrast‐agent (CA)‐enhanced normal, multiple sclerosis (MS), and glioblastoma (GBM) human brain data gives the mean capillary water molecule lifetime (τ b) and blood volume fraction (v b; capillary density–volume product (ρ † V)) in a high‐resolution 1H2O MRI voxel (40 μL) or ROI. The equilibrium water extravasation rate constant, k po (τ b −1), averages 3.2 and 2.9 s−1 in resting‐state normal white matter (NWM) and gray matter (NGM), respectively (n = 6). The results (italicized) lead to three major conclusions. (A) k po differences are dominated by capillary water permeability (P W †), not size, differences. NWM and NGM voxel k po and vb values are independent. Quantitative analyses of concomitant population‐averaged k po, vb variations in normal and normal‐appearing MS brain ROIs confirm PW † dominance. (B) P W † is dominated (>95%) by a trans(endothelial)cellular pathway, not the P CA † paracellular route. In MS lesions and GBM tumors, PCA † increases but PW † decreases. (C) k po tracks steady‐state ATP production/consumption flux per capillary. In normal, MS, and GBM brain, regional k po correlates with literature MRSI ATP (positively) and Na + (negatively) tissue concentrations. This suggests that the PW † pathway is metabolically active. Excellent agreement of the relative NGM/NWM k po vb product ratio with the literature 31PMRSI‐MT CMRoxphos ratio confirms the flux property. We have previously shown that the cellular water molecule efflux rate constant (k io) is proportional to plasma membrane P‐type ATPase turnover, likely due to active trans‐membrane water cycling. With synaptic proximities and synergistic metabolic cooperativities, polar brain endothelial, neuroglial, and neuronal cells form “gliovascular units.” We hypothesize that a chain of water cycling processes transmits brain metabolic activity to k po, letting it report neurogliovascular unit Na+,K+‐ATPase activity. Cerebral k po maps represent metabolic (functional) neuroimages. The NGM 2.9 s−1 k po means an equilibrium unidirectional water efflux of ~1015 H2O molecules s−1 per capillary (in 1 μL tissue): consistent with the known ATP consumption rate and water co‐transporting membrane symporter stoichiometries. © 2015 The Authors NMR in Biomedicine Published by John Wiley & Sons Ltd. PMID:25914365

Mach-like capillary-gravity wakes.

PubMed

Moisy, Frédéric; Rabaud, Marc

2014-08-01

We determine experimentally the angle α of maximum wave amplitude in the far-field wake behind a vertical surface-piercing cylinder translated at constant velocity U for Bond numbers Bo(D)=D/λ(c) ranging between 0.1 and 4.2, where D is the cylinder diameter and λ(c) the capillary length. In all cases the wake angle is found to follow a Mach-like law at large velocity, α∼U(-1), but with different prefactors depending on the value of Bo(D). For small Bo(D) (large capillary effects), the wake angle approximately follows the law α≃c(g,min)/U, where c(g,min) is the minimum group velocity of capillary-gravity waves. For larger Bo(D) (weak capillary effects), we recover a law α∼√[gD]/U similar to that found for ship wakes at large velocity [Rabaud and Moisy, Phys. Rev. Lett. 110, 214503 (2013)]. Using the general property of dispersive waves that the characteristic wavelength of the wave packet emitted by a disturbance is of order of the disturbance size, we propose a simple model that describes the transition between these two Mach-like regimes as the Bond number is varied. We show that the new capillary law α≃c(g,min)/U originates from the presence of a capillary cusp angle (distinct from the usual gravity cusp angle), along which the energy radiated by the disturbance accumulates for Bond numbers of order of unity. This model, complemented by numerical simulations of the surface elevation induced by a moving Gaussian pressure disturbance, is in qualitative agreement with experimental measurements.

Nailfold capillary morphological characteristics of hand-arm vibration syndrome: a cross-sectional study

PubMed Central

Chen, QingSong; Chen, GuiPing; Xiao, Bin; Lin, HanSheng; Qu, HongYing; Zhang, DanYing; Shi, MaoGong; Lang, Li; Yang, Bei; Yan, MaoSheng

2016-01-01

Objective The purpose of this study was to investigate the characteristics of nailfold capillaroscopy associated with hand-arm vibration syndrome (HAVS). Methods In total, 113 male gold miners were recruited: 35 workers who were chronically exposed to vibration and developed vibration-induced white finger were defined as the HAVS group, 39 workers who were exposed to vibration but did not have HAVS were classified as the vibration-exposed controls (VEC) group, and 39 workers without vibration exposure were categorised as the non-VEC (NVEC) group. Video capillaroscopy was used to capture images of the 2nd, 3rd and 4th fingers of both hands. The following nailfold capillary characteristics were included: number of capillaries/mm, avascular areas, haemorrhages and enlarged capillaries. The experiments were carried out in the same winter. All characteristics were evaluated under blinded conditions. Results Significant differences in all morphological characteristics existed between the groups (p<0.05). Avascular areas in the HAVS, VEC and NVEC groups appeared in 74.3%, 43.6% and 25.0% of participants, respectively. A higher percentage of participants had haemorrhages in the HAVS group (65.7%) compared with the other groups (VEC: 7.7% and NVEC: 7.5%). The number of capillaries/mm, input limb width, output limb width, apical width, and ratio of output limb and input limb all had more than 70% sensitivity or specificity of their cut-off value. Conclusions Nailfold capillary characteristics, especially the number of capillaries/mm, avascular areas, haemorrhages, output limb width, input limb width and apical width alterations, revealed significant associations with HAVS. PMID:27888176

MIA PaCa-2 and PANC-1 - pancreas ductal adenocarcinoma cell lines with neuroendocrine differentiation and somatostatin receptors.

PubMed

Gradiz, Rui; Silva, Henriqueta C; Carvalho, Lina; Botelho, Maria Filomena; Mota-Pinto, Anabela

2016-02-17

Studies using cell lines should always characterize these cells to ensure that the results are not distorted by unexpected morphological or genetic changes possibly due to culture time or passage number. Thus, the aim of this study was to describe those MIA PaCa-2 and PANC-1 cell line phenotype and genotype characteristics that may play a crucial role in pancreatic cancer therapeutic assays, namely neuroendocrine chemotherapy and peptide receptor radionuclide therapy. Epithelial, mesenchymal, endocrine and stem cell marker characterization was performed by immunohistochemistry and flow cytometry, and genotyping by PCR, gene sequencing and capillary electrophoresis. MIA PaCa-2 (polymorphism) expresses CK5.6, AE1/AE3, E-cadherin, vimentin, chromogranin A, synaptophysin, SSTR2 and NTR1 but not CD56. PANC-1 (pleomorphism) expresses CK5.6, MNF-116, vimentin, chromogranin A, CD56 and SSTR2 but not E-cadherin, synaptophysin or NTR1. MIA PaCA-1 is CD24(-), CD44(+/++), CD326(-/+) and CD133/1(-), while PANC-1 is CD24(-/+), CD44(+), CD326(-/+) and CD133/1(-). Both cell lines have KRAS and TP53 mutations and homozygous deletions including the first 3 exons of CDKN2A/p16(INK4A), but no SMAD4/DPC4 mutations or microsatellite instability. Both have neuroendocrine differentiation and SSTR2 receptors, precisely the features making them suitable for the therapies we propose to assay in future studies.

Capillary damage in the area postrema by venom of the northern black-tailed rattlesnake (Crotalus molossus molossus)

PubMed Central

Meléndez-Martínez, David; Macias-Rodríguez, Eduardo; Vargas-Caraveo, Alejandra; Martínez-Martínez, Alejandro; Gatica-Colima, Ana; Plenge-Tellechea, Luis Fernando

2014-01-01

The Northern black-tailed rattlesnake (Crotalus molossus molossus) venom is mainly hemotoxic, hemorrhagic, and neurotoxic. Its effects in the central nervous system are unknown and only poorly described for all Viperidae species in general. This is why we are interested in describe the damage induced by C. m. molossus venom in rat brain, particularly in the area postrema capillaries. Four C. m. molossus venom doses were tested (0.02, 0.05, 0.10 and 0.20mg/kg) injected intramuscularly at the lower limb, incubated by 24 hours and the brains were harvested. Area postrema coronal sections were stained with Haematoxylin and Eosin, and examined to observe the venom effect in quantity of capillaries and porphology. Starting from the 0.10mg/kg treatment we observed lysed extravasated erythrocytes and also capillary breakdown, as a consequence of hemorrhages appearance. The number of capillaries decreased significantly in response to the venom dose increment. Hemorrhages could be caused by the metalloproteinase activity on the basal membrane and the apoptosis generated by L-amino acid oxidases. Hemolysis could be caused by phospholipase A2 hemotoxic effect. We conclude that C. m. molossus crude venom produces hemolysis, capillary breakdown, hemorrhages, and the reduction in number of capillaries in the area postrema. PMID:25035793

Effect of Foam on Liquid Phase Mobility in Porous Media

NASA Astrophysics Data System (ADS)

Eftekhari, A. A.; Farajzadeh, R.

2017-03-01

We investigate the validity of the assumption that foam in porous media reduces the mobility of gas phase only and does not impact the liquid-phase mobility. The foam is generated by simultaneous injection of nitrogen gas and a surfactant solution into sandstone cores and its strength is varied by changing surfactant type and concentration. We find, indeed, that the effect of foam on liquid-phase mobility is not pronounced and can be ignored. Our new experimental results and analyses resolve apparent discrepancies in the literature. Previously, some researchers erroneously applied relative permeability relationships measured at small to moderate capillary numbers to foam floods at large capillary number. Our results indicate that the water relative permeability in the absence of surfactant should be measured with the capillary pressure ranging up to values reached during the foam floods. This requires conducting a steady-state gas/water core flood with capillary numbers similar to that of foam floods or measuring the water relative-permeability curve using a centrifuge.

Effect of Foam on Liquid Phase Mobility in Porous Media

PubMed Central

Eftekhari, A. A.; Farajzadeh, R.

2017-01-01

We investigate the validity of the assumption that foam in porous media reduces the mobility of gas phase only and does not impact the liquid-phase mobility. The foam is generated by simultaneous injection of nitrogen gas and a surfactant solution into sandstone cores and its strength is varied by changing surfactant type and concentration. We find, indeed, that the effect of foam on liquid-phase mobility is not pronounced and can be ignored. Our new experimental results and analyses resolve apparent discrepancies in the literature. Previously, some researchers erroneously applied relative permeability relationships measured at small to moderate capillary numbers to foam floods at large capillary number. Our results indicate that the water relative permeability in the absence of surfactant should be measured with the capillary pressure ranging up to values reached during the foam floods. This requires conducting a steady-state gas/water core flood with capillary numbers similar to that of foam floods or measuring the water relative-permeability curve using a centrifuge. PMID:28262795

A novel instrument for studying the flow behaviour of erythrocytes through microchannels simulating human blood capillaries.

PubMed

Sutton, N; Tracey, M C; Johnston, I D; Greenaway, R S; Rampling, M W

1997-05-01

A novel instrument has been developed to study the microrheology of erythrocytes as they flow through channels of dimensions similar to human blood capillaries. The channels are produced in silicon substrates using microengineering technology. Accurately defined, physiological driving pressures and temperatures are employed whilst precise, real-time image processing allows individual cells to be monitored continuously during their transit. The instrument characterises each cell in a sample of ca. 1000 in terms of its volume and flow velocity profile during its transit through a channel. The unique representation of the data in volume/velocity space provides new insight into the microrheological behaviour of blood. The image processing and subsequent data analysis enable the system to reject anomalous events such as multiple cell transits, thereby ensuring integrity of the resulting data. By employing an array of microfluidic flow channels we can integrate a number of different but precise and highly reproducible channel sizes and geometries within one array, thereby allowing multiple, concurrent isobaric measurements on one sample. As an illustration of the performance of the system, volume/velocity data sets recorded in a microfluidic device incorporating multiple channels of 100 microns length and individual widths ranging between 3.0 and 4.0 microns are presented.

Conditions for fluid separations in microchannels, capillary-driven fluid separations, and laminated devices capable of separating fluids

DOEpatents

TeGrotenhuis, Ward E [Kennewick, WA; Stenkamp, Victoria S [Richland, WA

2005-04-05

Methods of separating fluids using capillary forces and/or improved conditions for are disclosed. The improved methods may include control of the ratio of gas and liquid Reynolds numbers relative to the Suratman number. Also disclosed are wick-containing, laminated devices that are capable of separating fluids.

Conditions for fluid separations in microchannels, capillary-driven fluid separations, and laminated devices capable of separating fluids

DOEpatents

TeGrotenhuis, Ward E [Kennewick, WA; Stenkamp, Victoria S [Richland, WA

2008-03-18

Methods of separating fluids using capillary forces and/or improved conditions for are disclosed. The improved methods may include control of the ratio of gas and liquid Reynolds numbers relative to the Suratman number. Also disclosed are wick-containing, laminated devices that are capable of separating fluids.

Effect of viscosity on droplet-droplet collisional interaction

NASA Astrophysics Data System (ADS)

Finotello, Giulia; Padding, Johan T.; Deen, Niels G.; Jongsma, Alfred; Innings, Fredrik; Kuipers, J. A. M.

2017-06-01

A complete knowledge of the effect of droplet viscosity on droplet-droplet collision outcomes is essential for industrial processes such as spray drying. When droplets with dispersed solids are dried, the apparent viscosity of the dispersed phase increases by many orders of magnitude, which drastically changes the outcome of a droplet-droplet collision. However, the effect of viscosity on the droplet collision regime boundaries demarcating coalescence and reflexive and stretching separation is still not entirely understood and a general model for collision outcome boundaries is not available. In this work, the effect of viscosity on the droplet-droplet collision outcome is studied using direct numerical simulations employing the volume of fluid method. The role of viscous energy dissipation is analysed in collisions of droplets with different sizes and different physical properties. From the simulations results, a general phenomenological model depending on the capillary number (Ca, accounting for viscosity), the impact parameter (B), the Weber number (We), and the size ratio (Δ) is proposed.

Capillary isoelectric focusing of probiotic bacteria from cow's milk in tapered fused silica capillary with off-line matrix-assisted laser desorption/ionization time-of-flight mass spectrometry identification.

PubMed

Horká, Marie; Karásek, Pavel; Salplachta, Jiří; Růžička, Filip; Vykydalová, Marie; Kubesová, Anna; Dráb, Vladimír; Roth, Michal; Slais, Karel

2013-07-25

In this study, combination of capillary isoelectric focusing (CIEF) in tapered fused silica (FS) capillary with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is presented as an efficient approach for unambiguous identification of probiotic bacteria in real sample. For this purpose, bacteria within genus Lactobacillus were selected as model bioanalytes and cow's milk was selected as a biological sample. CIEF analysis of both the cultivated bacteria and the bacteria in the milk was optimized and isoelectric points characterizing the examined bacteria were subsequently determined independently of the bacterial sample origin. The use of tapered FS capillary significantly enhanced the separation capacity and efficiency of the CIEF analyses performed. In addition, the cell number injected into the tapered FS capillary was quantified and an excellent linearity of the calibration curves was achieved which enabled quantitative analysis of the bacteria by CIEF with UV detection. The minimum detectable number of bacterial cells was 2×10(6) mL(-1). Finally, cow's milk spiked with the selected bacterium was analyzed by CIEF in tapered FS capillary, the focused and detected bacterial cells were collected from the capillary, deposited onto the cultivation medium, and identified using MALDI-TOF MS afterward. Our results have revealed that the proposed procedure can be advantageously used for unambiguous identification of probiotic bacteria in a real sample. Copyright © 2013 Elsevier B.V. All rights reserved.

Lattice Boltzmann simulations of liquid CO2 displacing water in a 2D heterogeneous micromodel at reservoir pressure conditions.

PubMed

Chen, Yu; Li, Yaofa; Valocchi, Albert J; Christensen, Kenneth T

2018-05-01

We employed the color-fluid lattice Boltzmann multiphase model to simulate liquid CO 2 displacing water documented in experiments in a 2D heterogeneous micromodel at reservoir pressure conditions. The main purpose is to investigate whether lattice Boltzmann simulation can reproduce the CO 2 invasion patterns observed in these experiments for a range of capillary numbers. Although the viscosity ratio used in the simulation matches the experimental conditions, the viscosity of the fluids in the simulation is higher than that of the actual fluids used in the experiments. Doing so is required to enhance numerical stability, and is a common strategy employed in the literature when using the lattice Boltzmann method to simulate CO 2 displacing water. The simulations reproduce qualitatively similar trends of changes in invasion patterns as the capillary number is increased. However, the development of secondary CO 2 pathways, a key feature of the invasion patterns in the simulations and experiments, is found to occur at a much higher capillary number in the simulations compared with the experiments. Additional numerical simulations were conducted to investigate the effect of the absolute value of viscosity on the invasion patterns while maintaining the viscosity ratio and capillary number fixed. These results indicate that the use of a high viscosity (which significantly reduces the inertial effect in the simulations) suppresses the development of secondary CO 2 pathways, leading to a different fluid distribution compared with corresponding experiments at the same capillary number. Therefore, inertial effects are not negligible in drainage process with liquid CO 2 and water despite the low Reynolds number based on the average velocity, as the local velocity can be much higher due to Haines jump events. These higher velocities, coupled with the low viscosity of CO 2 , further amplifies the inertial effect. Therefore, we conclude that caution should be taken when using proxy fluids that only rely on the capillary number and viscosity ratio in both experiment and simulation. Copyright © 2017 Elsevier B.V. All rights reserved.

Direct Numerical Simulation of Low Capillary Number Pore Scale Flows

NASA Astrophysics Data System (ADS)

Esmaeilzadeh, S.; Soulaine, C.; Tchelepi, H.

2017-12-01

The arrangement of void spaces and the granular structure of a porous medium determines multiple macroscopic properties of the rock such as porosity, capillary pressure, and relative permeability. Therefore, it is important to study the microscopic structure of the reservoir pores and understand the dynamics of fluid displacements through them. One approach for doing this, is direct numerical simulation of pore-scale flow that requires a robust numerical tool for prediction of fluid dynamics and a detailed understanding of the physical processes occurring at the pore-scale. In pore scale flows with a low capillary number, Eulerian multiphase methods are well-known to produce additional vorticity close to the interface. This is mainly due to discretization errors which lead to an imbalance of capillary pressure and surface tension forces that causes unphysical spurious currents. At the pore scale, these spurious currents can become significantly stronger than the average velocity in the phases, and lead to unphysical displacement of the interface. In this work, we first investigate the capability of the algebraic Volume of Fluid (VOF) method in OpenFOAM for low capillary number pore scale flow simulations. Afterward, we compare VOF results with a Coupled Level-Set Volume of Fluid (CLSVOF) method and Iso-Advector method. It has been shown that the former one reduces the VOF's unphysical spurious currents in some cases, and both are known to capture interfaces sharper than VOF. As the conclusion, we will investigate that whether the use of CLSVOF or Iso-Advector will lead to less spurious velocities and more accurate results for capillary driven pore-scale multiphase flows or not. Keywords: Pore-scale multiphase flow, Capillary driven flows, Spurious currents, OpenFOAM

Nailfold capillary morphological characteristics of hand-arm vibration syndrome: a cross-sectional study.

PubMed

Chen, QingSong; Chen, GuiPing; Xiao, Bin; Lin, HanSheng; Qu, HongYing; Zhang, DanYing; Shi, MaoGong; Lang, Li; Yang, Bei; Yan, MaoSheng

2016-11-25

The purpose of this study was to investigate the characteristics of nailfold capillaroscopy associated with hand-arm vibration syndrome (HAVS). In total, 113 male gold miners were recruited: 35 workers who were chronically exposed to vibration and developed vibration-induced white finger were defined as the HAVS group, 39 workers who were exposed to vibration but did not have HAVS were classified as the vibration-exposed controls (VEC) group, and 39 workers without vibration exposure were categorised as the non-VEC (NVEC) group. Video capillaroscopy was used to capture images of the 2nd, 3rd and 4th fingers of both hands. The following nailfold capillary characteristics were included: number of capillaries/mm, avascular areas, haemorrhages and enlarged capillaries. The experiments were carried out in the same winter. All characteristics were evaluated under blinded conditions. Significant differences in all morphological characteristics existed between the groups (p<0.05). Avascular areas in the HAVS, VEC and NVEC groups appeared in 74.3%, 43.6% and 25.0% of participants, respectively. A higher percentage of participants had haemorrhages in the HAVS group (65.7%) compared with the other groups (VEC: 7.7% and NVEC: 7.5%). The number of capillaries/mm, input limb width, output limb width, apical width, and ratio of output limb and input limb all had more than 70% sensitivity or specificity of their cut-off value. Nailfold capillary characteristics, especially the number of capillaries/mm, avascular areas, haemorrhages, output limb width, input limb width and apical width alterations, revealed significant associations with HAVS. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Separation of plant hormones from biofertilizer by capillary electrophoresis using a capillary coated dynamically with polycationic polymers.

PubMed

Jiang, Ting-Fu; Lv, Zhi-Hua; Wang, Yuan-Hong; Yue, Mei-E

2006-06-01

A new, simple and rapid capillary electrophoresis (CE) method, using hexadimethrine bromide (HDB) as electroosmotic flow (EOF) modifier, was developed for the identification and quantitative determination of four plant hormones, including gibberellin A3 (GA3), indole-3-acetic acid (IAA), alpha-naphthaleneacetic acid (NAA) and 4-chlorophenoxyacetic acid (4-CA). The optimum separation was achieved with 20 mM borate buffer at pH 10.00 containing 0.005% (w/v) of HDB. The applied voltage was -25 kV and the capillary temperature was kept constant at 25 degrees C. Salicylic acid was used as internal standard for quantification. The calibration dependencies exhibited good linearity within the ratios of the concentrations of standard samples and internal standard and the ratios of the peak areas of samples and internal standard. The correlation coefficients were from 0.9952 to 0.9997. The relative standard deviations of migration times and peak areas were < 1.93 and 6.84%, respectively. The effects of buffer pH, the concentration of HDB and the voltage on the resolution were studied systematically. By this method, the contents of plant hormone in biofertilizer were successfully determined within 7 min, with satisfactory repeatability and recovery.

Rapid and Simple Capillary-Rise/Vanishing Interfacial Tension Method To Determine Crude Oil Minimum Miscibility Pressure: Pure and Mixed CO 2 , Methane, and Ethane

DOE PAGES

Hawthorne, Steven B.; Miller, David J.; Jin, Lu; ...

2016-07-20

We report here a simplification of the capillary-rise/vanishing interfacial tension (IFT) method to measure minimum miscibility pressure (MMP) based on only requiring knowledge of when the interfacial tension approaches zero. Simply measuring the height of the crude oil in a capillary at several pressures from ambient to near the MMP pressure and extrapolating the oil height versus pressure plot to zero oil height yields the MMP without the need of the additional instrumentation and labor required to perform actual IFT measurements. A total of 2−4 MMP values can be determined per day with only one experimental apparatus, and the methodmore » greatly reduces the initial cost and complexity of the required instrumentation. The use of three capillaries having different inner diameters allows for triplicate determinations of MMP from each experiment. Because the actual MMP pressure need not be reached during the experiment, MMP values that exceed the pressure ratings of the equipment can be reasonably estimated (e.g., MMPs using pure nitrogen). The method was used to determine the MMP pressure for crude oil samples from a conventional Muddy Formation reservoir in the Powder River Basin [American Petroleum Institute (API) gravity of 35.8°] and an unconventional Bakken Formation reservoir in the Williston Basin (API gravity of 38.7°). The method is reproducible [typically <4% relative standard deviation (RSD)], and the method gave good agreement for a “live” Bakken oil with the results from a slim tube test of a commercial laboratory. Approximately 80 MMP values were measured using pure CO2, methane, and ethane as well as 0−100% mole ratios of methane/CO2 and methane/ethane. For both oil samples, ethane MMPs were ca. one-half those with CO2, while methane MMPs were ca. double or triple those with CO2. MMPs with mixed methane/CO2 showed a linear increase with mole percent methane for both crude oils, while both oils showed an exponential increase in MMP with mole percent methane in ethane, with a little increase in MMP until ca. 20 mol % methane in ethane.« less

Effect of interfacial slip on the thin film drainage time for two equal-sized, surfactant-free drops undergoing a head-on collision: A scaling analysis

NASA Astrophysics Data System (ADS)

Ramachandran, A.; Leal, L. G.

2016-10-01

Using a scaling analysis, we assess the impact of interfacial slip on the time required for the thin liquid film between two drops undergoing a head-on collision to drain to the critical thickness for rupture by van der Waals forces. Interfacial slip is included in our continuum development using a Navier slip boundary condition, with the slip coefficient modeled using previous theories [Helfand and Tagami, J. Chem. Phys. 57, 1812 (1972), 10.1063/1.1678491; Goveas and Fredrickson, Eur. Phys. J. B 2, 79 (1998), 10.1007/s100510050228]. Slip decreases hydrodynamic resistance and speeds up film drainage. It renders the dependence of the drainage time on capillary number stronger in the spherical-film regime, but, interestingly, this dependence is altered only weakly in the dimpled-film regime. A subtle effect of slip is that it increases the range of capillary numbers in which the film remains predominantly spherical in shape during drainage (as opposed to being dimpled), leading to significantly faster drainage for these capillary numbers. Slip also leads to an increase in the critical capillary number beyond which coalescence is not possible in a head-collision.

Identification of viscous droplets' physical properties that determine droplet behaviors in inertial microfluidics

NASA Astrophysics Data System (ADS)

Hur, Soojung Claire

2013-11-01

Inertial effects in microfluidic systems have recently recognized as a robust and passive way of focusing and ordering microscale particles and cells continuously. Moreover, theoretical analysis has shown that there exists a force away from channel walls in Poiseuille flow that locates deformable particles closer to the channel center than rigid counterparts. Then, the particle deformability can be extrapolated from the positions of particles with known sizes in the channel. Here, behaviors of various viscous droplets in inertial flow were investigated to identify critical properties determining their dynamic lateral position. Fluorinated oil solutions (μ = 1.7 mPas and 5 mPas) containing droplets (1mPas< μ<1.3Pas) were injected into a microfluidic channel with a syringe pump (8 < Rc < 50). Interfacial tension between aqueous and oil phases were varied by adding controlled amount of a surfactant. The diameter, a, deformability, Def, and dynamic lateral position, Xeq, were determined using high-speed microscopy. Xeq, was found to correlate with the particle Capillary Number, CaP, regardless of droplet viscosities when CaP <0.02 or CaP >0.2, suggesting that the viscous drag from the continuous phase and the interfacial tension were competing factors determining Xeq. Experimental results suggested that (i) interplay among droplet's viscosity, interfacial tension and inertia of carrier fluid determines dynamic lateral position of droplets and (ii) the dominant property varies at a different regime.

Multiple capillary biochemical analyzer

DOEpatents

Dovichi, N.J.; Zhang, J.Z.

1995-08-08

A multiple capillary analyzer allows detection of light from multiple capillaries with a reduced number of interfaces through which light must pass in detecting light emitted from a sample being analyzed, using a modified sheath flow cuvette. A linear or rectangular array of capillaries is introduced into a rectangular flow chamber. Sheath fluid draws individual sample streams through the cuvette. The capillaries are closely and evenly spaced and held by a transparent retainer in a fixed position in relation to an optical detection system. Collimated sample excitation radiation is applied simultaneously across the ends of the capillaries in the retainer. Light emitted from the excited sample is detected by the optical detection system. The retainer is provided by a transparent chamber having inward slanting end walls. The capillaries are wedged into the chamber. One sideways dimension of the chamber is equal to the diameter of the capillaries and one end to end dimension varies from, at the top of the chamber, slightly greater than the sum of the diameters of the capillaries to, at the bottom of the chamber, slightly smaller than the sum of the diameters of the capillaries. The optical system utilizes optic fibers to deliver light to individual photodetectors, one for each capillary tube. A filter or wavelength division demultiplexer may be used for isolating fluorescence at particular bands. 21 figs.

Multiple capillary biochemical analyzer

DOEpatents

Dovichi, Norman J.; Zhang, Jian Z.

1995-01-01

A multiple capillary analyzer allows detection of light from multiple capillaries with a reduced number of interfaces through which light must pass in detecting light emitted from a sample being analyzed, using a modified sheath flow cuvette. A linear or rectangular array of capillaries is introduced into a rectangular flow chamber. Sheath fluid draws individual sample streams through the cuvette. The capillaries are closely and evenly spaced and held by a transparent retainer in a fixed position in relation to an optical detection system. Collimated sample excitation radiation is applied simultaneously across the ends of the capillaries in the retainer. Light emitted from the excited sample is detected by the optical detection system. The retainer is provided by a transparent chamber having inward slanting end walls. The capillaries are wedged into the chamber. One sideways dimension of the chamber is equal to the diameter of the capillaries and one end to end dimension varies from, at the top of the chamber, slightly greater than the sum of the diameters of the capillaries to, at the bottom of the chamber, slightly smaller than the sum of the diameters of the capillaries. The optical system utilizes optic fibres to deliver light to individual photodetectors, one for each capillary tube. A filter or wavelength division demultiplexer may be used for isolating fluorescence at particular bands.

Capillary condenser/evaporator

NASA Technical Reports Server (NTRS)

Valenzuela, Javier A. (Inventor)

2010-01-01

A heat transfer device is disclosed for transferring heat to or from a fluid that is undergoing a phase change. The heat transfer device includes a liquid-vapor manifold in fluid communication with a capillary structure thermally connected to a heat transfer interface, all of which are disposed in a housing to contain the vapor. The liquid-vapor manifold transports liquid in a first direction and conducts vapor in a second, opposite direction. The manifold provides a distributed supply of fluid (vapor or liquid) over the surface of the capillary structure. In one embodiment, the manifold has a fractal structure including one or more layers, each layer having one or more conduits for transporting liquid and one or more openings for conducting vapor. Adjacent layers have an increasing number of openings with decreasing area, and an increasing number of conduits with decreasing cross-sectional area, moving in a direction toward the capillary structure.

Experimental methods for the simulation of supercritical CO2 injection at laboratory scale aimed to investigate capillary trapping

NASA Astrophysics Data System (ADS)

Trevisan, L.; Illangasekare, T. H.; Rodriguez, D.; Sakaki, T.; Cihan, A.; Birkholzer, J. T.; Zhou, Q.

2011-12-01

Geological storage of carbon dioxide in deep geologic formations is being considered as a technical option to reduce greenhouse gas loading to the atmosphere. The processes associated with the movement and stable trapping are complex in deep naturally heterogeneous formations. Three primary mechanisms contribute to trapping; capillary entrapment due to immobilization of the supercritical fluid CO2 within soil pores, liquid CO2 dissolving in the formation water and mineralization. Natural heterogeneity in the formation is expected to affect all three mechanisms. A research project is in progress with the primary goal to improve our understanding of capillary and dissolution trapping during injection and post-injection process, focusing on formation heterogeneity. It is expected that this improved knowledge will help to develop site characterization methods targeting on obtaining the most critical parameters that capture the heterogeneity to design strategies and schemes to maximize trapping. This research combines experiments at the laboratory scale with multiphase modeling to upscale relevant trapping processes to the field scale. This paper presents the results from a set of experiments that were conducted in an intermediate scale test tanks. Intermediate scale testing provides an attractive alternative to investigate these processes under controlled conditions in the laboratory. Conducting these types of experiments is highly challenging as methods have to be developed to extrapolate the data from experiments that are conducted under ambient laboratory conditions to high temperatures and pressures settings in deep geologic formations. We explored the use of a combination of surrogate fluids that have similar density, viscosity contrasts and analogous solubility and interfacial tension as supercritical CO2-brine in deep formations. The extrapolation approach involves the use of dimensionless numbers such as Capillary number (Ca) and the Bond number (Bo). A set of experiments that captures some of the complexities of the geologic heterogeneity and injection scenarios are planned in a 4.8 m long tank. To test the experimental methods and instrumentation, a set of preliminary experiments were conducted in a smaller tank with dimensions 90 cm x 60 cm. The tank was packed to represent both homogeneous and heterogeneous conditions. Using the surrogate fluids, different injection scenarios were tested. Images of the migration plume showed the critical role that heterogeneity plays in stable entrapment. Destructive sampling done at the end of the experiments provided data on the final saturation distributions. Preliminary analysis suggests the entrapment configuration is controlled by the large-scale heterogeneities as well as the pore-scale entrapment mechanisms. The data was used in modeling analysis that is presented in a companion abstract.

Nailfold capillaroscopic changes in Kindler syndrome.

PubMed

Dobrev, Hristo P; Vutova, Nina I

2015-11-01

Kindler syndrome (KS), the fourth major type of hereditary epidermolysis bullosa (HEB), is a rare, autosomal recessive disorder characterized by skin fragility and blistering at birth followed by development of marked photosensitivity and progressive poikilodermatous skin changes in later years. We reported here the case of a 54-year-old woman, who fulfills the diagnostic criteria of KS type of HEB, putting accent on the nailfold capillaroscopic changes. Using videocapillaroscopy we observed pronounced alterations in finger nail capillaries including reduction in capillary density, features of neoangiogenesis (architectural derangement, elongated loops, extremely tortuous, bushy or branching capillaries, thin, branching and interconnected capillaries), enlarged and giant capillaries. We consider the changes observed as an adaptive mechanism that compensate the loss of capillaries due to chronic periungual trauma. Further studies with larger number of patients are needed to confirm the significance of capillaroscopy findings for patients with HEB.

Corner-transport-upwind lattice Boltzmann model for bubble cavitation

NASA Astrophysics Data System (ADS)

Sofonea, V.; Biciuşcǎ, T.; Busuioc, S.; Ambruş, Victor E.; Gonnella, G.; Lamura, A.

2018-02-01

Aiming to study the bubble cavitation problem in quiescent and sheared liquids, a third-order isothermal lattice Boltzmann model that describes a two-dimensional (2D) fluid obeying the van der Waals equation of state, is introduced. The evolution equations for the distribution functions in this off-lattice model with 16 velocities are solved using the corner-transport-upwind (CTU) numerical scheme on large square lattices (up to 6144 ×6144 nodes). The numerical viscosity and the regularization of the model are discussed for first- and second-order CTU schemes finding that the latter choice allows to obtain a very accurate phase diagram of a nonideal fluid. In a quiescent liquid, the present model allows us to recover the solution of the 2D Rayleigh-Plesset equation for a growing vapor bubble. In a sheared liquid, we investigated the evolution of the total bubble area, the bubble deformation, and the bubble tilt angle, for various values of the shear rate. A linear relation between the dimensionless deformation coefficient D and the capillary number Ca is found at small Ca but with a different factor than in equilibrium liquids. A nonlinear regime is observed for Ca≳0.2 .

Computation of shear-induced collective-diffusivity in emulsions

NASA Astrophysics Data System (ADS)

Malipeddi, Abhilash Reddy; Sarkar, Kausik

2017-11-01

The shear-induced collective-diffusivity of drops in an emulsion is calculated through simulation. A front-tracking finite difference method is used to integrate the Navier-Stokes equations. When a cloud of drops is subjected to shear flow, after a certain time, the width of the cloud increases with the 1/3 power of time. This scaling of drop-cloud-width with time is characteristic of (sub-)diffusion that arises from irreversible two-drop interactions. The collective diffusivity is calculated from this relationship. A feature of the procedure adopted here is the modest computational requirement, wherein, a few drops ( 70) in shear for short time ( 70 strain) is found to be sufficient to get a good estimate. As far as we know, collective-diffusivity has not been calculated for drops through simulation till now. The computed values match with experimental measurements reported in the literature. The diffusivity in emulsions is calculated for a range of Capillary (Ca) and Reynolds (Re) numbers. It is found to be a unimodal function of Ca , similar to self-diffusivity. A sub-linear increase of the diffusivity with Re is seen for Re < 5 . This work has been limited to a viscosity matched case.

Radiobiological experiments with plant seeds aboard the biosatellite Cosmos 1887

NASA Technical Reports Server (NTRS)

Benton, E. V.; Anikeeva, I. D.; Akatov, Yu. A.; Vaulina, E. N.; Kostina, L. N.; Marenny, A.; Portman, A. I.; Rusin, S. V.

1995-01-01

The effects of spaceflight factors on the seeds of Arabidopsis thaliana and Crepis capillaris were studied. The seeds were located inside the satellite in an open space, protected with aluminum foil and also exposed without the foil cover. When the seeds were in open space without any protection, their viability was found to be suppressed; the survival rate and fertility of plants grown from these seeds were also diminished. An increase in the frequency of chromosome aberrations (CA) and in the number of multiple injuries was registered in this case. Experiments with the aluminum foil shielding showed a decrease in the suppression of the seeds' viability, but mutational changes were found to be even more increased, while the survival rate and fertility of the plants decreased. An increase in the thickness of shielding resulted in a decrease in the effects up to the level of the control, except for the effects connected with CA and fertility of the plants. Analysis of the results shows that these impairments can be ascribed to the action of single heavy charged particles (HCP). The seeds can thus be regarded as an integral biological 'dosimeter' which allows estimation of the total effects of radiation, ecological and biological factors.

A visualization study on two-phase gravity drainage in porous media by using magnetic resonance imaging.

PubMed

Teng, Ying; Liu, Yu; Jiang, Lanlan; Song, Yongchen; Zhao, Jiafei; Zhang, Yi; Wang, Dayong

2016-09-01

Gravity drainage characteristics are important to improve our understanding of gas-liquid or liquid-liquid two-phase flow in porous media. Stable or unstable displacement fronts that controlled by the capillary force, viscous force, gravitational force, etc., are relevant features of immiscible two-phase flow. In this paper, three dimensionless parameters, namely, the gravity number, the capillary number and the Bond number, were used to describe the effect of the above mentioned forces on two-phase drainage features, including the displacement front and final displacing-phase saturation. A series of experiments on the downward displacement of a viscous fluid by a less viscous fluid in a vertical vessel that is filled with quartz beads are performed by using magnetic resonance imaging (MRI). The experimental results indicate that the wetting properties at both high and low capillary numbers exert remarkable control on the fluid displacement. When the contact angle is lower than 90°, i.e., the displaced phase is the wetting phase, the average velocity Vf of the interface of the two phases (displacement front velocity) is observably lower than when the displaced phase is the non-wetting phase (contact angle higher than 90°). The results show that a fingering phenomenon occurs when the gravity number G is less than the critical gravity number G'=Δμ/μg. Moreover, the higher Bond number results in higher final displacing-phase saturation, whereas the capillary number has an opposite effect. Copyright © 2016 Elsevier Inc. All rights reserved.

Water Displacement in Oil-Wet Tight Reservoirs by Dynamic Network Simulation

NASA Astrophysics Data System (ADS)

Wang, Y.; Li, M.; Chen, M.

2017-12-01

Pore network simulation is an effective tool for studying the multiphase flow in porous media. Based on the topological information and pore-throat size distribution obtained from the analysis of Scanning Electron Microscope (SEM) and constant-rate mercury injection (CRMI) for tight cores (composed by micro-nano scale throats and micro scale pores), a simple cubic (SC) pore-throat network was built with equilateral triangular cross-section throats and cubic bodies. Rules for oil and water movement and redistribution were devised in accordance with the physics process at pore-throat scale. Water flooding from oil-saturated under irreducible water were simulated by considering the changing displacement rate and viscosity ratio at the slightly oil-wet condition (the static contact angle ranges between π/2 to 2π/3). Different from the double pressure field algorithm, a single pressure field which solved by using successive over relaxation method was used with the flow of irreducible water in corners was ignored while its swilling was take into consideration. Dynamic of displacement fronts, relative permeability curves and residual oil saturation were obtained. It showed that there were obviously snap-off at low capillary number (Nc<10-5) and fingering at high capillary number (Nc<10-4) even at a favorable viscosity ratio (M=1). The magnitude of viscosity ratio effect on relative permeability depended largely on the capillary number, which the effect wasn't noticeable for a high capillary number. For residual oil saturation Sor, it showed that Sor decreased with the increase of capillary number at different viscosity ratio. Changing of residual oil saturation from simulation was in good agreement with the experimental results in a certain range, which indicated that this network model could be used to character the water flooding in tight reservoirs.

Lattice Boltzmann simulations of supercritical CO2-water drainage displacement in porous media: CO2 saturation and displacement mechanism.

PubMed

Yamabe, Hirotatsu; Tsuji, Takeshi; Liang, Yunfeng; Matsuoka, Toshifumi

2015-01-06

CO2 geosequestration in deep aquifers requires the displacement of water (wetting phase) from the porous media by supercritical CO2 (nonwetting phase). However, the interfacial instabilities, such as viscous and capillary fingerings, develop during the drainage displacement. Moreover, the burstlike Haines jump often occurs under conditions of low capillary number. To study these interfacial instabilities, we performed lattice Boltzmann simulations of CO2-water drainage displacement in a 3D synthetic granular rock model at a fixed viscosity ratio and at various capillary numbers. The capillary numbers are varied by changing injection pressure, which induces changes in flow velocity. It was observed that the viscous fingering was dominant at high injection pressures, whereas the crossover of viscous and capillary fingerings was observed, accompanied by Haines jumps, at low injection pressures. The Haines jumps flowing forward caused a significant drop of CO2 saturation, whereas Haines jumps flowing backward caused an increase of CO2 saturation (per injection depth). We demonstrated that the pore-scale Haines jumps remarkably influenced the flow path and therefore equilibrium CO2 saturation in crossover domain, which is in turn related to the storage efficiency in the field-scale geosequestration. The results can improve our understandings of the storage efficiency by the effects of pore-scale displacement phenomena.

Anisotropic capillary barrier for waste site surface covers

DOEpatents

Stormont, J.C.

1996-08-27

Waste sites are capped or covered upon closure. The cover structure incorporates a number of different layers each having a contributory function. One such layer is the barrier layer. Traditionally the barriers have been compacted soil and geosynthetics. These types of barriers have not been successfully implemented in unsaturated ground conditions like those found in dry climates. Capillary barriers have been proposed as barrier layers in dry environments, but the divergence length of these barriers has been found to be inadequate. An alternative to the capillary barrier is a anisotropic capillary barrier. An anisotropic capillary barrier has an increased divergence length which results in more water being diverted laterally preventing the majority of water from percolating in a downward direction through the barrier. 10 figs.

Anisotropic capillary barrier for waste site surface covers

DOEpatents

Stormont, John C.

1996-01-01

Waste sites are capped or covered upon closure. The cover structure incorporates a number of different layers each having a contributory function. One such layer is the barrier layer. Traditionally the barriers have been compacted soil and geosynthetics. These types of barriers have not been successfully implemented in unsaturated ground conditions like those found in dry climates. Capillary barriers have been proposed as barrier layers in dry environments, but the divergence length of these barriers has been found to be inadequate. An alternative to the capillary barrier is a anisotropic capillary barrier. An anisotropic capillary barrier has an increased divergence length which results in more water being diverted laterally preventing the majority of water from percolating in a downward direction through the barrier.

Incorporating the Impacts of Small Scale Rock Heterogeneity into Models of Flow and Trapping in Target UK CO2 Storage Systems

NASA Astrophysics Data System (ADS)

Jackson, S. J.; Reynolds, C.; Krevor, S. C.

2017-12-01

Predictions of the flow behaviour and storage capacity of CO2 in subsurface reservoirs are dependent on accurate modelling of multiphase flow and trapping. A number of studies have shown that small scale rock heterogeneities have a significant impact on CO2flow propagating to larger scales. The need to simulate flow in heterogeneous reservoir systems has led to the development of numerical upscaling techniques which are widely used in industry. Less well understood, however, is the best approach for incorporating laboratory characterisations of small scale heterogeneities into models. At small scales, heterogeneity in the capillary pressure characteristic function becomes significant. We present a digital rock workflow that combines core flood experiments with numerical simulations to characterise sub-core scale capillary pressure heterogeneities within rock cores from several target UK storage reservoirs - the Bunter, Captain and Ormskirk sandstone formations. Measured intrinsic properties (permeability, capillary pressure, relative permeability) and 3D saturations maps from steady-state core flood experiments were the primary inputs to construct a 3D digital rock model in CMG IMEX. We used vertical end-point scaling to iteratively update the voxel by voxel capillary pressure curves from the average MICP curve; with each iteration more closely predicting the experimental saturations and pressure drops. Once characterised, the digital rock cores were used to predict equivalent flow functions, such as relative permeability and residual trapping, across the range of flow conditions estimated to prevail in the CO2 storage reservoirs. In the case of the Captain sandstone, rock cores were characterised across an entire 100m vertical transect of the reservoir. This allowed analysis of the upscaled impact of small scale heterogeneity on flow and trapping. Figure 1 shows the varying degree to which heterogeneity impacted flow depending on the capillary number in the Captain sandstone. At low capillary numbers, typical of regions where flow is dominated by buoyancy, fluid flow is impeded and trapping enhanced. At high capillary numbers, typical of the near wellbore environment, the fluid distributed homogeneously and the equivalent relative permeability was higher leading to improved injectivity.

Quantitative fine structure of capillaries in subregions of the rat subfornical organ.

PubMed

Shaver, S W; Sposito, N M; Gross, P M

1990-04-01

The differentiated cytology across subregions of the rat subfornical organ (SFO) prompted our hypothesis that ultrastructural features of capillary endothelial cells would vary topographically and quantitatively within this small nucleus. We used electron microscopic and computer-based morphometric methods to assess fine structural dimensions of the capillary endothelium in four distinct subregions of the SFO from Long-Evans and homozygous Brattleboro rats. Three types of capillary were present. Type III capillaries (resembling those of endocrine glands) had an average wall thickness of 0.17 microns, 54% thinner than those of Type I and II capillaries. Pericapillary spaces around Type III capillaries measured 56 microns2, 100% larger than for Type I vessels (resembling those of skeletal muscle). Only Type III capillaries contained fenestrations (9 per microns2 of endothelial cell) and were the predominant type of capillary in central and caudal subregions of the SFO. Type I capillaries, prevalent in the transitional subregion between the central and rostral parts of the SFO, had 10 cytoplasmic vesicles per micron2 of endothelial cell area, a number not different from that of Type III capillaries but 3x the frequency found in Type II vessels. Type II capillaries (those typical of "blood-brain barrier" endothelium) had low vesicular density (3 per microns2), no fenestrations, and no pericapillary spaces. Luminal diameters and the densities of mitochondria and intercellular junctions were not different among capillary types or subregions in the SFO. Furthermore, there were no morphometric differences for any capillary dimensions between Long-Evans and Brattleboro rats.(ABSTRACT TRUNCATED AT 250 WORDS)

DNA-directed trypsin immobilization on a polyamidoamine dendrimer-modified capillary to form a renewable immobilized enzyme microreactor.

PubMed

Wu, Nan; Wang, Siming; Yang, Ye; Song, Jiayi; Su, Ping; Yang, Yi

2018-07-01

A novel type of trypsin capillary microreactor was developed based on a DNA-directed immobilization (DDI) technique applied to a fused-silica capillary modified with polyamidoamine (PAMAM) dendrimers. Trypsin binding to the inner wall of the capillary was confirmed by confocal laser scanning microscopy. The properties of the trypsin-DNA conjugated, PAMAM-modified capillary microreactor were investigated by monitoring hydrolysis of Nα-benzoyl- L -arginine ethyl ester. Through the hybridization and dehybridization of the DNA, the inner wall of the capillary functionalized with trypsin can be regenerated, thus indicating the renewability of this enzyme microreactor. In addition, these results demonstrated that introduction of PAMAM enabled higher amounts of trypsin to be immobilized, markedly improving the enzymolysis efficiency, compared with traditional modified capillaries. The digestion performance of the trypsin capillary microreactor was further evaluated by digesting cytochrome C, and a peptide numbers of 8, and a sequence coverage of 59% were obtained. This renewable and efficient immobilized trypsin capillary microreactor combines advantages of both DDI technology and PAMAM, and is potentially adaptable to high-throughput enzyme assays in biochemical and clinical research. Copyright © 2018. Published by Elsevier B.V.

Capillary electrochromatography of inorganic cations in open tubular columns with a controllable capacity multilayered stationary phase architecture.

PubMed

Kubán, Pavel; Kubán, Petr; Kubán, Vlastimil; Hauser, Peter C; Bocek, Petr

2008-05-09

In this paper capillary electrochromatography of alkali and alkaline-earth metal cations in open tubular capillary columns is described. Capillary columns are prepared by coating fused silica capillaries of 75 microm I.D. with poly(butadiene-maleic acid) copolymer (PBMA) in multiple layers. Thermally initiated radical polymerization is used to crosslink the stationary phase. Capillary columns with different number of stationary phase layers can be prepared and allow for the adjustment of separation selectivity in the electrochromatographic mode. Fast and sensitive separations of common inorganic cations are achieved in less than 6 min in a 60 cm capillary column with on-column capacitively coupled contactless conductivity detector. Limits of detection (S/N=3) for the determination of alkali and alkaline-earth metal cations range from 0.3 to 2.5 microM and repeatability is better than 0.5, 4.5 and 6.1% for migration times, peak heights and peak areas, respectively.

Immunocytochemical localization of carbonic anhydrase in the pseudobranch tissue of the rainbow trout Oncorhynchus mykiss.

PubMed

Rahim, S M; Mazlan, A G; Simon, K D; Delaunoy, J P; Laurent, P

2014-02-01

Pseudobranch function has long interested scientists, but its role has yet to be elucidated. Several studies have suggested that pseudobranchs serve respiratory, osmoregulatory, and sensory functions. This work investigated the immunolocalization of pseudobranch carbonic anhydrase (CA) in the teleost fish species rainbow trout (Oncorhynchus mykiss) to clarify its physiological function. CA was purified from rainbow trout gills O. mykiss and specific antibodies were raised. Immunoblotting between tissue homogenates of pseudobranch and gill CA antibodies showed specific immunostaining with only one band corresponding to CA in the pseudobranch homogenate. Results of immunohistochemical technique revealed that CA was distributed within pseudobranch cells and more precisely in the apical parts (anti-vascular) of cells. The basal (vascular) parts of cells, tubular system, blood capillaries, and pillar cells were not immunostained. Immunocytochemistry confirmed these results and showed that some CA enzyme was cytoplasmic and the remainder was linked to membranous structures. The results also showed that the lacunar tissue layers did not display immunoperoxidase activity. Our results indicated that pseudobranch CA may have a function related to the extracellular medium wherein CA intervenes with the mechanism of stimulation of afferent nerve fibers.

SPECTRAL DOMAIN VERSUS SWEPT SOURCE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY OF THE RETINAL CAPILLARY PLEXUSES IN SICKLE CELL MACULOPATHY.

PubMed

Jung, Jesse J; Chen, Michael H; Frambach, Caroline R; Rofagha, Soraya; Lee, Scott S

2018-01-01

To compare the spectral domain and swept source optical coherence tomography angiography findings in two cases of sickle cell maculopathy. A 53-year-old man and a 24-year-old man both with sickle cell disease (hemoglobin SS) presented with no visual complaints; Humphrey visual field testing demonstrated asymptomatic paracentral scotomas that extended nasally in the involved eyes. Clinical examination and multimodal imaging including spectral domain and swept source optical coherence tomography, and spectral domain optical coherence tomography angiography and swept source optical coherence tomography angiography (Carl Zeiss Meditec Inc, Dublin, CA) were performed. Fundus examination of both patients revealed subtle thinning of the macula. En-face swept source optical coherence tomography confirmed the extent of the thinning correlating with the functional paracentral scotomas on Humphrey visual field. Swept source optical coherence tomography B-scan revealed multiple confluent areas of inner nuclear thinning and significant temporal retinal atrophy. En-face 6 × 6-mm spectral domain optical coherence tomography angiography of the macula demonstrated greater loss of the deep capillary plexus compared with the superficial capillary plexus. Swept source optical coherence tomography angiography 12 × 12-mm imaging captured the same macular findings and loss of both plexuses temporally outside the macula. In these two cases of sickle cell maculopathy, deep capillary plexus ischemia is more extensive within the macula, whereas both the superficial capillary plexus and deep capillary plexus are involved outside the macula likely due to the greater oxygen demands and watershed nature of these areas. Swept source optical coherence tomography angiography clearly demonstrates the angiographic extent of the disease correlating with the Humphrey visual field scotomas and confluent areas of inner nuclear atrophy.

Local CD34-positive capillaries decrease in mouse models of kidney disease associating with the severity of glomerular and tubulointerstitial lesions.

PubMed

Masum, Md Abdul; Ichii, Osamu; Elewa, Yaser Hosny Ali; Nakamura, Teppei; Kon, Yasuhiro

2017-09-04

The renal vasculature plays important roles in both homeostasis and pathology. In this study, we examined pathological changes in the renal microvascular in mouse models of kidney diseases. Glomerular lesions (GLs) in autoimmune disease-prone male BXSB/MpJ-Yaa (Yaa) mice and tubulointerstitial lesions (TILs) in male C57BL/6 mice subjected to unilateral ureteral obstruction (UUO) for 7 days were studied. Collected kidneys were examined using histopathological techniques. A nonparametric Mann-Whitney U test (P < 0.05) was performed to compare healthy controls and the experimental mice. The Kruskal-Wallis test was used to compare three or more groups, and multiple comparisons were performed using Scheffe's method when significant differences were observed (P < 0.05). Yaa mice developed severe autoimmune glomerulonephritis, and the number of CD34 + glomerular capillaries decreased significantly in GLs compared to that in control mice. However, UUO-treated mice showed severe TILs only, and CD34 + tubulointerstitial capillaries were decreased significantly in TILs with the progression of tubulointerstitial fibrosis compared to those in untreated control kidneys. Infiltrations of B-cells, T-cells, and macrophages increased significantly in the respective lesions of both disease models (P < 0.05). In observations of vascular corrosion casts by scanning electron microscopy and of microfil rubber-perfused thick kidney sections by fluorescence microscopy, segmental absences of capillaries were observed in the GLs and TILs of Yaa and UUO-treated mice, respectively. Further, transmission electron microscopy revealed capillary endothelial injury in the respective lesions of both models. The numbers of CD34 + glomerular and tubulointerstitial capillaries were negatively correlated with all examined parameters in GLs (P < 0.05) and TILs (P < 0.01), respectively. From the analysis of mouse models, we identified inverse pathological correlations between the number of local capillaries in GLs and TILs and the severity of kidney diseases.

Fluid mechanics phenomena in microgravity; ASME Winter Annual Meeting, Anaheim, CA, Nov. 8-13, 1992

NASA Technical Reports Server (NTRS)

Siginer, Dennis A. (Editor); Weislogel, Mark M. (Editor)

1992-01-01

This paper is the first in a series of symposia presenting research activity in microgravity fluid mechanics. General topics addressed include two-phase flow and transport phenomena, thermo-capillary flow, and interfacial stability. Papers present mathmatical models of fluid dynamics in the microgravity environment. Applications suggested include space manufacturing and storage of liquids in low gravity.

Capillary Movement in Substrates in Microgravity

NASA Technical Reports Server (NTRS)

Bula, R. J.; Duffie, N. A.

1996-01-01

A more complete understanding of the dynamics of capillary flow through an unsaturated porous medium would be useful for a number of space and terrestrial applications. Knowledge of capillary migration of liquids in granular beds in microgravity would significantly enhance the development and understanding of how a matrix based nutrient delivery system for the growth of plants would function in a microgravity environment. Thus, such information is of interest from the theoretical as well as practical point of view.

Germline PTPN11 and somatic PIK3CA variant in a boy with megalencephaly-capillary malformation syndrome (MCAP) - pure coincidence?

PubMed Central

Döcker, Dennis; Schubach, Max; Menzel, Moritz; Spaich, Christiane; Gabriel, Heinz-Dieter; Zenker, Martin; Bartholdi, Deborah; Biskup, Saskia

2015-01-01

Megalencephaly-capillary malformation (MCAP) syndrome is an overgrowth syndrome that is diagnosed by clinical criteria. Recently, somatic and germline variants in genes that are involved in the PI3K-AKT pathway (AKT3, PIK3R2 and PIK3CA) have been described to be associated with MCAP and/or other related megalencephaly syndromes. We performed trio-exome sequencing in a 6-year-old boy and his healthy parents. Clinical features were macrocephaly, cutis marmorata, angiomata, asymmetric overgrowth, developmental delay, discrete midline facial nevus flammeus, toe syndactyly and postaxial polydactyly—thus, clearly an MCAP phenotype. Exome sequencing revealed a pathogenic de novo germline variant in the PTPN11 gene (c.1529A>G; p.(Gln510Arg)), which has so far been associated with Noonan, as well as LEOPARD syndrome. Whole-exome sequencing (>100 × coverage) did not reveal any alteration in the known megalencephaly genes. However, ultra-deep sequencing results from saliva (>1000 × coverage) revealed a 22% mosaic variant in PIK3CA (c.2740G>A; p.(Gly914Arg)). To our knowledge, this report is the first description of a PTPN11 germline variant in an MCAP patient. Data from experimental studies show a complex interaction of SHP2 (gene product of PTPN11) and the PI3K-AKT pathway. We hypothesize that certain PTPN11 germline variants might drive toward additional second-hit alterations. PMID:24939587

Germline PTPN11 and somatic PIK3CA variant in a boy with megalencephaly-capillary malformation syndrome (MCAP)--pure coincidence?

PubMed

Döcker, Dennis; Schubach, Max; Menzel, Moritz; Spaich, Christiane; Gabriel, Heinz-Dieter; Zenker, Martin; Bartholdi, Deborah; Biskup, Saskia

2015-03-01

Megalencephaly-capillary malformation (MCAP) syndrome is an overgrowth syndrome that is diagnosed by clinical criteria. Recently, somatic and germline variants in genes that are involved in the PI3K-AKT pathway (AKT3, PIK3R2 and PIK3CA) have been described to be associated with MCAP and/or other related megalencephaly syndromes. We performed trio-exome sequencing in a 6-year-old boy and his healthy parents. Clinical features were macrocephaly, cutis marmorata, angiomata, asymmetric overgrowth, developmental delay, discrete midline facial nevus flammeus, toe syndactyly and postaxial polydactyly--thus, clearly an MCAP phenotype. Exome sequencing revealed a pathogenic de novo germline variant in the PTPN11 gene (c.1529A>G; p.(Gln510Arg)), which has so far been associated with Noonan, as well as LEOPARD syndrome. Whole-exome sequencing (>100 × coverage) did not reveal any alteration in the known megalencephaly genes. However, ultra-deep sequencing results from saliva (>1000 × coverage) revealed a 22% mosaic variant in PIK3CA (c.2740G>A; p.(Gly914Arg)). To our knowledge, this report is the first description of a PTPN11 germline variant in an MCAP patient. Data from experimental studies show a complex interaction of SHP2 (gene product of PTPN11) and the PI3K-AKT pathway. We hypothesize that certain PTPN11 germline variants might drive toward additional second-hit alterations.

Effects of the inner droplet of double emulsions on the film drainage during a head-on collision

NASA Astrophysics Data System (ADS)

Wang, Jingtao; Jing, Hefeng; Xu, Genmiao; Wang, Xiaoyong; Duan, Zhenya

2015-07-01

As a critical stage which severely affects the final coalescence of droplets, film drainage in the collision process of two simple droplets has been deeply studied for many years. However, the collision of multiple emulsions which contain other phases (like daughter droplets or particles) has never been studied although multiple emulsions are very important in emulsion industries nowadays. In this paper, the head-on collision of two core-shell double emulsions with equal sizes is investigated through a boundary integral method to disclose the effects of the inner droplet on the film drainage. When capillary number Ca is relatively high, due to the effect of the inner droplet on the inner circulation of mother droplets, the film drainage of double emulsions includes three stages: drainage, drainage halt, and second drainage, instead of two stages for that of simple droplets: drainage and drainage halt.

Bubble deformations and segmented flows in corrugated microchannels at large capillary numbers

NASA Astrophysics Data System (ADS)

Sauzade, Martin; Cubaud, Thomas

2018-03-01

We experimentally investigate the interaction between individual bubble deformations and collective distortions of segmented flows in nonlinear microfluidic geometries. Using highly viscous carrier fluids, we study the evolution of monodisperse trains of gas bubbles from a square to a smoothly corrugated microchannel characterized with a series of extensions and constrictions along the flow path. The hysteresis in the bubble shape between accelerating and decelerating flow fields is shown to increase with the capillary number. Measurements of instantaneous bubble velocities reveal the presence of a capillary pull that produces a nonmonotonic behavior for the front velocity in accelerating flow regions. Functional relationships are developed for predicting the morphology and dynamics of viscous multiphase flow patterns at the pore scale.

Mechanism of oil bank formation, coalescence in porous media and emulsion and foam stability. Quarterly research progress report, July 1, 1984-September 30, 1984

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wasan, D.T.

The relative permeability model for two phase flow in porous media (Wasan 1983; Ramakrishnan and Wasan 1984) provides the necessary fractional flow curves at a given capillary number. These curves can be utilized in modeling both enhanced secondary and tertiary recovery processes. Important parameters in the fractional flow curves of our relative permeability model are the residual wetting and nonwetting phase saturations in a low capillary number flooding process. To understand, what constitutes the residual saturations, this quarter we have studied the displacement of one incompressible fluid by another in a porous medium using the network representation. The Bernoulli percolationmore » model for an infinite lattice graph is utilized in the interpretation of the capillary behavior of the medium, which ultimately determines residual saturations. The calculated capillary pressure-saturation relationship using Bethe lattice results agrees qualitatively with experimental data. 4 references, 2 figures.« less

Use of vancomycin silica stationary phase in packed capillary electrochromatography: III. enantiomeric separation of basic compounds with the polar organic mobile phase.

PubMed

Fanali, Salvatore; Catarcini, Paolo; Quaglia, Maria Giovanna

2002-02-01

The separation of basic compounds into their enantiomers was achieved using capillary electrochromatography in 50 or 75 microm inner diameter (ID) fused-silica capillaries packed with silica a stationary phase derivatized with vancomycin and mobile phases composed of mixtures of polar organic solvents containing 13 mM ammonium acetate. Enantiomer resolution, electroosmotic flow, and the number of theoretical plates were strongly influenced by the type and concentration of the organic solvent. Mobile phases composed of 13 mM ammonium acetate dissolved in mixtures of acetonitrile/methanol, ethanol, n-propanol, or isopropanol were tested and the highest enantioresolutions were achieved using the first mobile phase, allowing the separation of almost all investigated enantiomers (9 from 11 basic compounds). The use of capillaries with different ID (50 and 75 microm ID) packed with the same chiral stationary phase revealed that a higher number of theoretical plates and higher enantioresolution was achieved with the tube with lowest ID.

Evaluation of mast cells, eosinophils, blood capillaries in oral lichen planus and oral lichenoid mucositis.

PubMed

Reddy, D Santhosh; Sivapathasundharam, B; Saraswathi, T R; SriRam, G

2012-01-01

Mast cells are granule containing secretory cells present in oral mucosal and connective tissue environment. Oral lichen planus and oral lichenoid lesions are commonly occurring oral diseases and have some similarity clinically and histologically. Both are characterized by an extensive sub epithelial infiltrate of T cells, together with mast cells, eosinophils and blood capillaries. In this study mast cell and eosinophil densities along with number of blood capillaries were studied to find out if they could aid in histopathological distinction between oral lichen planus and lichenoid mucositis. To enumerate mast cells and compare the status of Mast Cells (Intact or Degranulated) in Lichen planus, Lichenoid mucositis and normal buccal mucosa in tissue sections stained with Toluidine Blue, and also to enumerate Eosinophils and blood capillaries in tissue sections stained with H and E. The study group included 30 cases each of oral lichen planus and oral lichenoid mucositis. 10 cases of clinically normal oral buccal mucosa formed the control group. All the sections were stained with Toluidine blue and H and E separately. Histopathological analysis was done using binocular light microscope equipped with square ocular grid to standardize the field of evaluation. The result of the study showed. · Significant increase in number of mast cells in oral lichen planus and oral lichenoid mucositis compared to normal buccal mucosa. · Significant increase of intact mast cells suepithelially within the inflammatory cell infiltrate in oral lichen planus compared to oral lichenoid mucositis. · Significant increase of degranulated mast cells in oral lichenoid mucositis to oral lichen planus, and increase in number of eosinophil densities in oral lichenoid mucositis compared to oral lichen planus. · Significant increase in number of capillaries in oral lichenoid mucositis compared to oral lichen planus. The findings of increased number of intact mast cells sub epithelially in oral lichen planus to oral lichenoid mucositis and increase in number of degranulated mast cells as well as capillaries subepithelially in oral lichenoid mucositis to oral lichen planus can be used as reliable criteria for histologic distinction between these two lesions. The increase of eosinophils in oral lichenoid mucositis to oral lichen planus could be used as adjunct histologic criterion in the diagnosis of oral lichenoid mucositis.

Diabetic microangiopathy in capillaroscopic examination of juveniles with diabetes type 1.

PubMed

Kaminska-Winciorek, Grażyna; Deja, Grażyna; Polańska, Joanna; Jarosz-Chobot, Przemysława

2012-01-30

The aim of this work was a quantitative and qualitative assessment of a selected part of the microcirculation in children with diabetes type 1 using videocapillaroscopy technique. The authors tested a group consisting of 145 children (70 boys, 75 girls) diagnosed and treated for diabetes type 1 in the Diabetic Clinic of GCZD in Katowice for at least one year. The study included history, clinical examination (including dermatological examination) and videocapillaroscopy. Capillaroscopy, a non-invasive, painless and easily repeatable test, was performed using videocapillaroscopy with digital storage of the obtained images. All nailfolds were examined in all children using videocapillaroscopy, and the obtained images were assessed quantitatively and qualitatively for changes in capillary loops in the tested children according to the defined diagnostic procedure. The analysis of capillaroscopic images described selected quantitative and qualitative characteristics. The conducted analysis showed an increase in the number of capillaries and their elongation, the presence of megacapillaries and Raynaud loops, which were accompanied by an intensive red background, indicating possible neoangiogenesis. The increase in the number of capillaries, disturbances in distribution of capillaries and the presence of abnormal capillaries were correlated with the longer duration of diabetes. Raynaud loops were more frequently found in the cases of increased mean values of HbA1c. Higher values of HbA1c influenced the capillaroscopic images, mainly the number of vessels, including Raynaud loops. Videocapillaroscopy technique could be a useful tool to detect the early changes of microangiopathy in children with diabetes type 1.

Nailfold capillaroscopy for day-to-day clinical use: construction of a simple scoring modality as a clinical prognostic index for digital trophic lesions.

PubMed

Smith, Vanessa; De Keyser, Filip; Pizzorni, Carmen; Van Praet, Jens T; Decuman, Saskia; Sulli, Alberto; Deschepper, Ellen; Cutolo, Maurizio

2011-01-01

Construction of a simple nailfold videocapillaroscopic (NVC) scoring modality as a prognostic index for digital trophic lesions for day-to-day clinical use. An association with a single simple (semi)-quantitatively scored NVC parameter, mean score of capillary loss, was explored in 71 consecutive patients with systemic sclerosis (SSc), and reliable reduction in the number of investigated fields (F32-F16-F8-F4). The cut-off value of the prognostic index (mean score of capillary loss calculated over a reduced number of fields) for present/future digital trophic lesions was selected by receiver operating curve (ROC) analysis. Reduction in the number of fields for mean score of capillary loss was reliable from F32 to F8 (intraclass correlation coefficient of F16/F32: 0.97; F8/F32: 0.90). Based on ROC analysis, a prognostic index (mean score of capillary loss as calculated over F8) with a cut-off value of 1.67 is proposed. This value has a sensitivity of 72.22/70.00, specificity of 70.59/69.77, positive likelihood ratio of 2.46/2.32 and a negative likelihood ratio of 0.39/0.43 for present/future digital trophic lesions. A simple prognostic index for digital trophic lesions for daily use in SSc clinics is proposed, limited to the mean score of capillary loss as calculated over eight fields (8 fingers, 1 field per finger).

Steady propagation of Bingham plugs in 2D channels

NASA Astrophysics Data System (ADS)

Zamankhan, Parsa; Takayama, Shuichi; Grotberg, James

2009-11-01

The displacement of the yield-stress liquid plugs in channels and tubes occur in many biological systems and industrial processes. Among them is the propagation of mucus plugs in the respiratory tracts as may occur in asthma, cystic fibrosis, or emphysema. In this work the steady propagation of mucus plugs in a 2D channel is studied numerically, assuming that the mucus is a pure Bingham fluid. The governing equations are solved by a mixed-discontinuous finite element formulation and the free surface is resolved with the method of spines. The constitutive equation for a pure Bingham fluid is modeled by a regularization method. Fluid inertia is neglected, so the controlling parameters in a steady displacement are; the capillary number, Ca, Bingham number ,Bn, and the plug length. According to the numerical results, the yield stress behavior of the plug modifies the plug shape, the pattern of the streamlines and the distribution of stresses in the plug domain and along the walls in a significant way. The distribution along the walls is a major factor in studying cell injuries. This work is supported through the grant NIH HL84370.

Performance of Different “Lab-On-Chip” Geometries for Making Double Emulsions to Form Polystyrene Shells

DOE PAGES

Viza, N. D.; Harding, D. R.

2017-12-20

Fluid properties and the geometry of lab-on-chip (LOC) designs together affect the formation of double emulsions for making inertial confinement fusion targets. Critical fluid properties include the fluids’ velocities and interfacial tension—a coupled effect that is best characterized by the capillary number (Ca)—and the relative volumetric flow rates (φ). The important geometry of the LOC is the orientation of the channels where they intersect (junction) and the spacing between successive junctions. T-junctions and focus-flow devices were tested. The latter geometry of a double cross (focus flow) performed better: single-emulsion droplets were formed over a wide range of fluid parameters (0.03more » < φ < 0.17 and 0.0003 < Ca < 0.001) at the first junction, and double emulsions were formed over a more limited range (φ > 0.5 and Ca < 0.4) at the second junction. A LOC design using the focus-flow design formed water–oil–water (W/O/W) double emulsions with the oil phase containing polystyrene. The double emulsions yielded shells with an outer dimension ranging from 2.3±0.07 mm to 4.3±0.23 mm and a wall thickness ranging from 30 μm to 1.6 mm. Thus, the value of the flow-rate ratio at the second junction provided the most-effective parameter for controlling the inner diameter, outer diameter, and wall thickness of the shell.« less

Performance of Different “Lab-On-Chip” Geometries for Making Double Emulsions to Form Polystyrene Shells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Viza, N. D.; Harding, D. R.

Fluid properties and the geometry of lab-on-chip (LOC) designs together affect the formation of double emulsions for making inertial confinement fusion targets. Critical fluid properties include the fluids’ velocities and interfacial tension—a coupled effect that is best characterized by the capillary number (Ca)—and the relative volumetric flow rates (φ). The important geometry of the LOC is the orientation of the channels where they intersect (junction) and the spacing between successive junctions. T-junctions and focus-flow devices were tested. The latter geometry of a double cross (focus flow) performed better: single-emulsion droplets were formed over a wide range of fluid parameters (0.03more » < φ < 0.17 and 0.0003 < Ca < 0.001) at the first junction, and double emulsions were formed over a more limited range (φ > 0.5 and Ca < 0.4) at the second junction. A LOC design using the focus-flow design formed water–oil–water (W/O/W) double emulsions with the oil phase containing polystyrene. The double emulsions yielded shells with an outer dimension ranging from 2.3±0.07 mm to 4.3±0.23 mm and a wall thickness ranging from 30 μm to 1.6 mm. Thus, the value of the flow-rate ratio at the second junction provided the most-effective parameter for controlling the inner diameter, outer diameter, and wall thickness of the shell.« less

Computational analysis of microbubble flows in bifurcating airways: role of gravity, inertia, and surface tension.

PubMed

Chen, Xiaodong; Zielinski, Rachel; Ghadiali, Samir N

2014-10-01

Although mechanical ventilation is a life-saving therapy for patients with severe lung disorders, the microbubble flows generated during ventilation generate hydrodynamic stresses, including pressure and shear stress gradients, which damage the pulmonary epithelium. In this study, we used computational fluid dynamics to investigate how gravity, inertia, and surface tension influence both microbubble flow patterns in bifurcating airways and the magnitude/distribution of hydrodynamic stresses on the airway wall. Direct interface tracking and finite element techniques were used to simulate bubble propagation in a two-dimensional (2D) liquid-filled bifurcating airway. Computational solutions of the full incompressible Navier-Stokes equation were used to investigate how inertia, gravity, and surface tension forces as characterized by the Reynolds (Re), Bond (Bo), and Capillary (Ca) numbers influence pressure and shear stress gradients at the airway wall. Gravity had a significant impact on flow patterns and hydrodynamic stress magnitudes where Bo > 1 led to dramatic changes in bubble shape and increased pressure and shear stress gradients in the upper daughter airway. Interestingly, increased pressure gradients near the bifurcation point (i.e., carina) were only elevated during asymmetric bubble splitting. Although changes in pressure gradient magnitudes were generally more sensitive to Ca, under large Re conditions, both Re and Ca significantly altered the pressure gradient magnitude. We conclude that inertia, gravity, and surface tension can all have a significant impact on microbubble flow patterns and hydrodynamic stresses in bifurcating airways.

Effect of surfactants on the deformation of single droplet in shear flow studied by dissipative particle dynamics

NASA Astrophysics Data System (ADS)

Zhang, Yuzhou; Xu, Junbo; He, Xianfeng

2018-07-01

The behaviour of a single droplet in shear flow is a fundamental problem in immiscible liquid-liquid multiphase fluid systems. In this article, the deformation and inclination angle of single droplet covered with surfactants in shear flow at moderate Reynolds number, when both the inertial effects and interfacial tension are the key governing factors, were simulated by dissipative particle dynamics (DPD). Weber number We was adopted to indicate the force state of the droplet and a linear relationship between the deformation parameter D and We was found when Reynolds number Re is about 1-10, which is similar to the relation of D and Capillary number Ca when Re ≪ 1. When the surfactant concentration is lower than the critical micelle concentration (CMC), the distribution of surfactants, the droplet inclination angle θ and the droplet deformation parameter D were investigated at different surfactant density at interface ds and shear rate ?. When the droplet size is close to the characteristic size of surfactant molecules, phase interfaces of water in oil (W/O) and oil in water (O/W) systems have different microstructures, which result in differences in the surfactant distribution, the droplet inclination angle and deformation of the two systems.

CAPILLARY ELECTROPHORESIS IMMUNOASSAY FOR 2,4-DICHLOROPHENOXYACETIC ACID

EPA Science Inventory

A capillary electrophoresis (CE) immunoassay format for 2,4-dichlorophenoxyacetic acid (2,4-D) is demonstrated. A fluorescent labeled 2,4-D analog competes with the analyte of interest for a finite number of binding sites provided by anti-2,4-D monoclonal antibodies. CE then pr...

TRPV4 channels stimulate Ca2+-induced Ca2+ release in astrocytic endfeet and amplify neurovascular coupling responses.

PubMed

Dunn, Kathryn M; Hill-Eubanks, David C; Liedtke, Wolfgang B; Nelson, Mark T

2013-04-09

In the CNS, astrocytes are sensory and regulatory hubs that play important roles in cerebral homeostatic processes, including matching local cerebral blood flow to neuronal metabolism (neurovascular coupling). These cells possess a highly branched network of processes that project from the soma to neuronal synapses as well as to arterioles and capillaries, where they terminate in "endfeet" that encase the blood vessels. Ca(2+) signaling within the endfoot mediates neurovascular coupling; thus, these functional microdomains control vascular tone and local perfusion in the brain. Transient receptor potential vanilloid 4 (TRPV4) channels--nonselective cation channels with considerable Ca(2+) conductance--have been identified in astrocytes, but their function is largely unknown. We sought to characterize the influence of TRPV4 channels on Ca(2+) dynamics in the astrocytic endfoot microdomain and assess their role in neurovascular coupling. We identified local TRPV4-mediated Ca(2+) oscillations in endfeet and further found that TRPV4 Ca(2+) signals are amplified and propagated by Ca(2+)-induced Ca(2+) release from inositol trisphosphate receptors (IP3Rs). Moreover, TRPV4-mediated Ca(2+) influx contributes to the endfoot Ca(2+) response to neuronal activation, enhancing the accompanying vasodilation. Our results identify a dynamic synergy between TRPV4 channels and IP3Rs in astrocyte endfeet and demonstrate that TRPV4 channels are engaged in and contribute to neurovascular coupling.

Increased transfer of 45Ca into brain and cerebrospinal fluid from plasma during chronic hypocalcemia in rats.

PubMed

Murphy, V A; Rapoport, S I

1988-06-28

Recent studies have shown regulation of central nervous system [Ca] after chronic hypo- and hypercalcemia. To investigate the mechanism of this regulation, 3-week-old rats were fed diets for 8 weeks that contained low or normal levels of Ca. Plasma [Ca] was 40% less in rats fed the low Ca diet than in animals fed normal diet. Unidirectional transfer coefficients for Ca (KCa) and Cl (KCl) into cerebrospinal fluid (CSF) and brain were determined from the 10 min uptake of intravenously injected 45Ca and 36Cl in awake animals. KCa for CSF was 68% greater in low-Ca rats than in normal rats. Likewise, the values of KCa for brain regions with areas adjacent to the ventricles like the hippocampus and pons-medulla were 50% higher than in normal animals. On the other hand, KCas for parietal cortex, a brain region distant from the choroid plexus and not expected to be influenced by Ca entry into CSF, were similar between the groups. Comparison of the regional ratios of KCa/KCl revealed that a selective increase of Ca transport occurred into CSF and all brain regions except the parietal cortex in Ca-deficient rats. The results suggest that Ca homeostasis of CSF and brain [Ca] during chronic hypocalcemia is due to increased transfer of Ca from blood to brain, and that the regulation occurs via the CSF, possibly at the choroid plexus, but not via the cerebral capillaries.

Evaporation effect on two-dimensional wicking in porous media.

PubMed

Benner, Eric M; Petsev, Dimiter N

2018-03-15

We analyze the effect of evaporation on expanding capillary flow for losses normal to the plane of a two-dimensional porous medium using the potential flow theory formulation of the Lucas-Washburn method. Evaporation induces a finite steady state liquid flux on capillary flows into fan-shaped domains which is significantly greater than the flux into media of constant cross section. We introduce the evaporation-capillary number, a new dimensionless quantity, which governs the frontal motion when multiplied by the scaled time. This governing product divides the wicking behavior into simple regimes of capillary dominated flow and evaporative steady state, as well as the intermediate regime of evaporation influenced capillary driven motion. We also show flow dimensionality and evaporation reduce the propagation rate of the wet front relative to the Lucas-Washburn law. Copyright © 2017 Elsevier Inc. All rights reserved.

Modeling shear-induced particle ordering and deformation in a dense soft particle suspension

NASA Astrophysics Data System (ADS)

Liao, Chih-Tang; Wu, Yi-Fan; Chien, Wei; Huang, Jung-Ren; Chen, Yeng-Long

2017-11-01

We apply the lattice Boltzmann method and the bead-spring network model of deformable particles (DPs) to study shear-induced particle ordering and deformation and the corresponding rheological behavior for dense DP suspensions confined in a narrow gap under steady external shear. The particle configuration is characterized with small-angle scattering intensity, the real-space 2D local order parameter, and the particle shape factors including deformation, stretching and tilt angles. We investigate how particle ordering and deformation vary with the particle volume fraction ϕ (=0.45-0.65) and the external shear rate characterized with the capillary number Ca (=0.003-0.191). The degree of particle deformation increases mildly with ϕ but significantly with Ca. Under moderate shear rate (Ca  =  0.105), the inter-particle structure evolves from string-like ordering to layered hexagonal close packing (HCP) as ϕ increases. A long wavelength particle slithering motion emerges for sufficiently large ϕ. For ϕ  =  0.61, the structure maintains layered HCP for Ca  =  0.031-0.143 but gradually becomes disordered for larger and smaller Ca. The correlation in particle zigzag movements depends sensitively on ϕ and particle ordering. Layer-by-layer analysis reveals how the non-slippery hard walls affect particle ordering and deformation. The shear-induced reconfiguration of DPs observed in the simulation agrees qualitatively with experimental results of sheared uniform emulsions. The apparent suspension viscosity increases with ϕ but exhibits much weaker dependence compared to hard-sphere suspensions, indicating that particle deformation and unjamming under shear can significantly reduce the viscous stress. Furthermore, the suspension shear-thins, corresponding to increased inter-DP ordering and particle deformation with Ca. This work provides useful insights into the microstructure-rheology relationship of concentrated deformable particle suspensions.

Modeling shear-induced particle ordering and deformation in a dense soft particle suspension.

PubMed

Liao, Chih-Tang; Wu, Yi-Fan; Chien, Wei; Huang, Jung-Ren; Chen, Yeng-Long

2017-11-01

We apply the lattice Boltzmann method and the bead-spring network model of deformable particles (DPs) to study shear-induced particle ordering and deformation and the corresponding rheological behavior for dense DP suspensions confined in a narrow gap under steady external shear. The particle configuration is characterized with small-angle scattering intensity, the real-space 2D local order parameter, and the particle shape factors including deformation, stretching and tilt angles. We investigate how particle ordering and deformation vary with the particle volume fraction ϕ (=0.45-0.65) and the external shear rate characterized with the capillary number Ca (=0.003-0.191). The degree of particle deformation increases mildly with ϕ but significantly with Ca. Under moderate shear rate (Ca  =  0.105), the inter-particle structure evolves from string-like ordering to layered hexagonal close packing (HCP) as ϕ increases. A long wavelength particle slithering motion emerges for sufficiently large ϕ. For ϕ  =  0.61, the structure maintains layered HCP for Ca  =  0.031-0.143 but gradually becomes disordered for larger and smaller Ca. The correlation in particle zigzag movements depends sensitively on ϕ and particle ordering. Layer-by-layer analysis reveals how the non-slippery hard walls affect particle ordering and deformation. The shear-induced reconfiguration of DPs observed in the simulation agrees qualitatively with experimental results of sheared uniform emulsions. The apparent suspension viscosity increases with ϕ but exhibits much weaker dependence compared to hard-sphere suspensions, indicating that particle deformation and unjamming under shear can significantly reduce the viscous stress. Furthermore, the suspension shear-thins, corresponding to increased inter-DP ordering and particle deformation with Ca. This work provides useful insights into the microstructure-rheology relationship of concentrated deformable particle suspensions.

The accuracy of home glucose meters in hypoglycemia.

PubMed

Sonmez, Alper; Yilmaz, Zeynep; Uckaya, Gokhan; Kilic, Selim; Tapan, Serkan; Taslipinar, Abdullah; Aydogdu, Aydogan; Yazici, Mahmut; Yilmaz, Mahmut Ilker; Serdar, Muhittin; Erbil, M Kemal; Kutlu, Mustafa

2010-08-01

Home glucose meters (HGMs) may not be accurate enough to sense hypoglycemia. We evaluated the accuracy and the capillary and venous comparability of five different HGMs (Optium Xceed [Abbott Diabetes Care, Alameda, CA, USA], Contour TS [Bayer Diabetes Care, Basel, Switzerland], Accu-Chek Go [Roche Ltd., Basel, Switzerland], OneTouch Select [Lifescan, Milpitas, CA, USA], and EZ Smart [Tyson Bioresearch Inc., Chu-Nan, Taiwan]) in an adult population. The insulin hypoglycemia test was performed to 59 subjects (56 males; 23.6 +/- 3.2 years old). Glucose was measured from forearm venous blood and finger capillary samples both before and after regular insulin (0.1 U/kg) was injected. Venous samples were analyzed in the reference laboratory by the hexokinase method. In vitro tests for method comparison and precision analyses were also performed by spiking the glucose-depleted venous blood. All HGMs failed to sense hypoglycemia to some extend. EZ Smart was significantly inferior in critical error Zone D, and OneTouch Select was significantly inferior in the clinically unimportant error Zone B. Accu-Chek Go, Optium Xceed, and Contour TS had similar performances and were significantly better than the other two HGMs according to error grid analysis or International Organization for Standardization criteria. The in vitro tests were consistent with the above clinical data. The capillary and venous consistencies of Accu-Chek Go and OneTouch Select were better than the other HGMs. The present results show that not all the HGMs are accurate enough in low blood glucose levels. The patients and the caregivers should be aware of these restrictions of the HGMs and give more credit to the symptoms of hypoglycemia than the values obtained by the HGMs. Finally, these results indicate that there is a need for the revision of the accuracy standards of HGMs in low blood glucose levels.

Capillarization in skeletal muscle of rats with cardiac hypertrophy.

PubMed

Degens, Hans; Anderson, Rebecca K; Alway, Stephen E

2002-02-01

Exercise intolerance during chronic heart failure (CHF) is localized mainly in skeletal muscle. A decreased capillarization may impair exchange of oxygen between capillaries and muscle tissue and in this way contribute to exercise intolerance. We assessed changes in capillary supply in plantaris and diaphragm muscles of a rat aorta-caval fistula (ACF) preparation, a volume overload model for CHF. An ACF was created under equithesin anesthesia. Plantaris and diaphragm muscles were removed 6 wk postsurgery and examined for myosin heavy chain (MyHC) content and capillary supply. Cardiac hypertrophy was 96% (P < 0.002) after ACF. The Type IIb MyHC content of the plantaris muscles increased (33.9 +/- 3.3 vs 49.8 +/- 3.8%; mean +/- SEM) at the expense of Type IIa MyHC (17.6 +/- 1.8 vs 11.2 +/- 1.7%) in ACF rats (P < 0.05). In the diaphragm, the number of Type I (32.1 +/- 2.3 vs 40.6 +/- 2.7%) and IIb fibers (40.6 +/- 1.9 vs 49.6 +/- 3.6%) increased at the expense of Type IIa fibers (26.8 +/- 2.5 vs 9.4 +/- 0.9%) (P < 0.05). The capillary number per fiber did not change, and this indicated that no capillary loss occurred with ACF. Also, the capillary density was maintained in the diaphragm and plantaris muscles of ACF rats. Furthermore, the coupling between fiber type, size, and metabolic type of surrounding fibers, with the capillary supply to a fiber, was maintained in rats with an ACF. The cardiac hypertrophy induced by volume overload seems adequate to prevent atrophy and changes in the microcirculation of limb and diaphragm muscles.

Modeling steady state SO2-dependent changes in capillary ATP concentration using novel O2 micro-delivery methods

PubMed Central

Ghonaim, Nour W.; Fraser, Graham M.; Ellis, Christopher G.; Yang, Jun; Goldman, Daniel

2013-01-01

Adenosine triphosphate (ATP) is known to be released from the erythrocyte in an oxygen (O2) dependent manner. Since ATP is a potent vasodilator, it is proposed to be a key regulator in the pathway that mediates micro-vascular response to varying tissue O2 demand. We propose that ATP signaling mainly originates in the capillaries due to the relatively long erythrocyte transit times in the capillary and the short ATP diffusion distance to the electrically coupled endothelium. We have developed a computational model to investigate the effect of delivering or removing O2 to limited areas at the surface of a tissue with an idealized parallel capillary array on total ATP concentration. Simulations were conducted when exposing full surface to perturbations in tissue O2 tension (PO2) or locally using a circular micro-outlet (~100 μm in diameter), a square micro-slit (200 × 200 μm), or a rectangular micro-slit (1000 μm wide × 200 μm long). Results indicated the rectangular micro-slit has the optimal dimensions for altering hemoglobin saturations (SO2) in sufficient number capillaries to generate effective changes in total [ATP]. This suggests a threshold for the minimum number of capillaries that need to be stimulated in vivo by imposed tissue hypoxia to induce a conducted micro-vascular response. SO2 and corresponding [ATP] changes were also modeled in a terminal arteriole (9 μm in diameter) that replaces 4 surface capillaries in the idealized network geometry. Based on the results, the contribution of terminal arterioles to the net change in [ATP] in the micro-vascular network is minimal although they would participate as O2 sources thus influencing the O2 distribution. The modeling data presented here provide important insights into designing a novel micro-delivery device for studying micro-vascular O2 regulation in the capillaries in vivo. PMID:24069001

Wettability Control on Fluid-Fluid Displacements in Patterned Microfluidics

NASA Astrophysics Data System (ADS)

Zhao, B.; Trojer, M.; Cueto-Felgueroso, L.; Juanes, R.

2014-12-01

Two-phase flow in porous media is important in many natural and industrial processes like geologic CO2 sequestration, enhanced oil recovery, and water infiltration in soil. While it is well known that the wetting properties of porous media can vary drastically depending on the type of media and the pore fluids, the effect of wettability on fluid displacement continues to challenge our microscopic and macroscopic descriptions. Here we study this problem experimentally, starting with the classic experiment of two-phase flow in a capillary tube. We image the shape of the meniscus and measure the associated capillary pressure for a wide range of capillary numbers. We confirm that wettability exerts a fundamental control on meniscus deformation, and synthesize new observations on the dependence of the dynamic capillary pressure on wetting properties (contact angle) and flow conditions (viscosity contrast and capillary number). We compare our experiments to a macroscopic phase-field model of two-phase flow. We use the insights gained from the capillary tube experiments to explore the viscous fingering instability in the Hele-Shaw geometry in the partial-wetting regime. A key difference between a Hele-Shaw cell and a porous medium is the existence of micro-structures (i.e. pores and pore throats). To investigate how these micro-structrues impact fluid-fluid displacement, we conduct experiments on a planar microfluidic device patterned with vertical posts. We track the evolution of the fluid-fluid interface and elucidate the impact of wetting on the cooperative nature of fluid displacement during pore invasion events. We use the insights gained from the capillary tube and patterned microfluidics experiments to elucidate the effect of wetting properties on viscous fingering and capillary fingering in a Hele-Shaw cell filled with glass beads, where we observe a contact-angle-dependent stabilizing behavior for the emerging flow instabilities, as the system transitions from drainage to imbibition.

Radiobiological experiments with plant seeds aboard the biosatellite Kosmos 1887

NASA Technical Reports Server (NTRS)

Anikeeva, I. D.; Vaulina, E. N.; Kostina, L. N.; Marenny, A. M.; Portman, A. I.; Rusin, S. V.; Benton, E. V.

1990-01-01

The effects of spaceflight factors on the seeds of Arabidopsis thaliana and Crepis capillaris were studied provided with various protective measures: the seeds were located inside the satellite and in open space, protected with aluminium foil and also exposed without the foil cover. When the seeds were in open space without any protection, their viability was found to be suppressed; the survival rate and fertility of plants grown from these seeds were also diminished. An increase in the frequency of chromosome aberrations (CA) and in the number of multiple injuries was registered in this case. Experiments with the aluminium foil shielding showed a decrease in the suppression of the seeds' viability, but mutational changes were found to be even more increased, while the survival and fertility of the plants decreased. An increase in the thickness of shielding resulted in a decrease in the effects up to the level of the control, except for the effects connected with CA and fertility of the plants. Analysis of the results shows that these impairments can be ascribed to the action of single heavy charged particles (HCP). The seeds can be thus regarded as an integral biological 'dosimeter' which allows estimation of the total effects of radiation, ecological and biological factors.

Radiobiological experiments with plant seeds aboard the biosatellite Kosmos 1887.

PubMed

Anikeeva, I D; Akatov YuA; Vaulina, E N; Kostina, L N; Marenny, A M; Portman, A I; Rusin, S V; Benton, E V

1990-01-01

The effects of spaceflight factors on the seeds of Arabidopsis thaliana and Crepis capillaris were studied provided with various protective measures: the seeds were located inside the satellite and in open space, protected with aluminium foil and also exposed without the foil cover. When the seeds were in open space without any protection, their viability was found to be suppressed; the survival rate and fertility of plants grown from these seeds were also diminished. An increase in the frequency of chromosome aberrations (CA) and in the number of multiple injuries was registered in this case. Experiments with the aluminium foil shielding showed a decrease in the suppression of the seeds' viability, but mutational changes were found to be even more increased, while the survival and fertility of the plants decreased. An increase in the thickness of shielding resulted in a decrease in the effects up to the level of the control, except for the effects connected with CA and fertility of the plants. Analysis of the results shows that these impairments can be ascribed to the action of single heavy charged particles (HCP). The seeds can be thus regarded as an integral biological 'dosimeter' which allows estimation of the total effects of radiation, ecological and biological factors.

Analysis of the Therapeutic Potential of Stem Cells to Facilitate Recovery from Cardiac Disease and Damage

DTIC Science & Technology

2012-07-01

fraction (as assessed using echocardiography ), infarct area, and number of new capillaries (capillaries will be detected by Isolectin B staining and...assessed prior to Infarction (basetlne)and 30 days after treatment by echocardiography . Mason~s trichrome and lsole<:tln B4 staining were utilized

Investigation of energy dissipation due to contact angle hysteresis in capillary effect

NASA Astrophysics Data System (ADS)

Athukorallage, Bhagya; Iyer, Ram

2016-06-01

Capillary action or Capillarity is the ability of a liquid to flow in narrow spaces without the assistance of, and in opposition to, external forces like gravity. Three effects contribute to capillary action, namely, adhesion of the liquid to the walls of the confining solid; meniscus formation; and low Reynolds number fluid flow. We investigate the dissipation of energy during one cycle of capillary action, when the liquid volume inside a capillary tube first increases and subsequently decreases while assuming quasi-static motion. The quasi-static assumption allows us to focus on the wetting phenomenon of the solid wall by the liquid and the formation of the meniscus. It is well known that the motion of a liquid on an non-ideal surface involves the expenditure of energy due to contact angle hysteresis. In this paper, we derive the equations for the menisci and the flow rules for the change of the contact angles for a liquid column in a capillary tube at a constant temperature and volume by minimizing the Helmholtz free energy using calculus of variations. We describe the numerical solution of these equations and present results from computations for the case of a capillary tube with 1 mm diameter.

Connective Tissue Growth Factor Is Involved in Structural Retinal Vascular Changes in Long-Term Experimental Diabetes

PubMed Central

Van Geest, Rob J.; Leeuwis, Jan Willem; Dendooven, Amélie; Pfister, Frederick; Bosch, Klazien; Hoeben, Kees A.; Vogels, Ilse M.C.; Van der Giezen, Dionne M.; Dietrich, Nadine; Hammes, Hans-Peter; Goldschmeding, Roel; Klaassen, Ingeborg; Van Noorden, Cornelis J.F.

2014-01-01

Early retinal vascular changes in the development of diabetic retinopathy (DR) include capillary basal lamina (BL) thickening, pericyte loss and the development of acellular capillaries. Expression of the CCN (connective tissue growth factor/cysteine-rich 61/nephroblastoma overexpressed) family member CCN2 or connective tissue growth factor (CTGF), a potent inducer of the expression of BL components, is upregulated early in diabetes. Diabetic mice lacking one functional CTGF allele (CTGF+/−) do not show this BL thickening. As early events in DR may be interrelated, we hypothesized that CTGF plays a role in the pathological changes of retinal capillaries other than BL thickening. We studied the effects of long-term (6-8 months) streptozotocin-induced diabetes on retinal capillary BL thickness, numbers of pericytes and the development of acellular capillaries in wild type and CTGF+/− mice. Our results show that an absence of BL thickening of retinal capillaries in long-term diabetic CTGF+/− mice is associated with reduced pericyte dropout and reduced formation of acellular capillaries. We conclude that CTGF is involved in structural retinal vascular changes in diabetic rodents. Inhibition of CTGF in the eye may therefore be protective against the development of DR. PMID:24217924

Molecular and Functional Characterization of Three Different Postzygotic Mutations in PIK3CA-Related Overgrowth Spectrum (PROS) Patients: Effects on PI3K/AKT/mTOR Signaling and Sensitivity to PIK3 Inhibitors

PubMed Central

Forte, Giovanna; Bagnulo, Rosanna; Stella, Alessandro; Lastella, Patrizia; Cutrone, Mario; Benedicenti, Francesco; Susca, Francesco C.; Patruno, Margherita; Varvara, Dora; Germani, Aldo; Chessa, Luciana; Laforgia, Nicola; Tenconi, Romano; Simone, Cristiano; Resta, Nicoletta

2015-01-01

Background PIK3CA-related overgrowth spectrum (PROS) include a group of disorders that affect only the terminal portion of a limb, such as type I macrodactyly, and conditions like fibroadipose overgrowth (FAO), megalencephaly-capillary malformation (MCAP) syndrome, congenital lipomatous asymmetric overgrowth of the trunk, lymphatic, capillary, venous, and combined-type vascular malformations, epidermal nevi, skeletal and spinal anomalies (CLOVES) syndrome and Hemihyperplasia Multiple Lipomatosis (HHML). Heterozygous postzygotic PIK3CA mutations are frequently identified in these syndromes, while timing and tissue specificity of the mutational event are likely responsible for the extreme phenotypic variability observed. Methods We carried out a combination of Sanger sequencing and targeted deep sequencing of genes involved in the PI3K/AKT/mTOR pathway in three patients (1 MCAP and 2 FAO) to identify causative mutations, and performed immunoblot analyses to assay the phosphorylation status of AKT and P70S6K in affected dermal fibroblasts. In addition, we evaluated their ability to grow in the absence of serum and their response to the PI3K inhibitors wortmannin and LY294002 in vitro. Results and Conclusion Our data indicate that patients’ cells showed constitutive activation of the PI3K/Akt pathway. Of note, PI3K pharmacological blockade resulted in a significant reduction of the proliferation rate in culture, suggesting that inhibition of PI3K might prove beneficial in future therapies for PROS patients. PMID:25915946

Capillary Discharge Thruster Experiments and Modeling (Briefing Charts)

DTIC Science & Technology

2016-06-01

Martin1 ERC INC.1, IN-SPACE PROPULSION BRANCH, AIR FORCE RESEARCH LABORATORY EDWARDS AIR FORCE BASE, CA USA Electric propulsion systems June 2016... PROPULSION MODELS & EXPERIMENTS Spacecraft Propulsion Relevant Plasma: From hall thrusters to plumes and fluxes on components Complex reaction physics i.e... Propulsion Plumes FRC Chamber Environment R.S. MARTIN (ERC INC.) DISTRIBUTION A: APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED; PA# 16279 3 / 30 ELECTRIC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Renkin, E.M.; Gustafson-Sgro, M.; Sibley, L.

Bovine serum albumin (BSA) labeled with /sup 131/I or /sup 125/I was injected intravenously in pentobarbital sodium-anesthetized rats, and tracer clearances into leg skin and muscles were measured over 30, 60, and 120 min. BSA labeled with the alternate tracer was used as vascular volume reference. Two minutes before injection of the tracer, a ligature was tied around one femoral vein to occlude outflow partially and raise capillary pressure in that leg. The unoccluded leg served as control. Skin and muscles of the occluded leg had variably and substantially higher water contents (delta W) than paired control tissues and slightlymore » but consistently increased albumin clearances (CA). The delta CA/delta W, equivalent to the albumin concentration of capillary filtrate relative to plasma determined by linear regression, were as follows: leg skin 0.004 (95% confidence limits -0.001 to +0.009), muscle biceps femoris 0.005 (0.001-0.010), muscle gastrocnemius 0.011 (0.004-0.019), muscle tibialis anterior 0.016 (0.012-0.021). All these values are significantly less than 0.10, which corresponds to a reflection coefficient for serum albumin (sigma A) of 0.90. Convective coupling of albumin flux to volume flux in skin and muscles of intact, anesthetized rats is low, with sigma AS in the range 0.98 to greater than 0.99.« less

Irradiation of orderly multiline spectra from linear plasma formed by vacuum discharge capillary

NASA Astrophysics Data System (ADS)

Sato, Eiichi; Hayasi, Yasuomi; Germer, Rudolf; Ojima, Hidenori; Takayama, Kazuyoshi; Ido, Hideaki

2005-03-01

The fundamental experiments for measuring soft x-ray characteristics from the vacuum capillary are described. These experiments are primarily performed in order to generate intense soft x rays. The generator consists of a high-voltage power supply, a polarity-inversion ignitron pulse generator, a turbomolecular pump, and a radiation tube with a capillary. A high-voltage condenser of 200 nF in the pulse generator is charged up to 20 kV by the power supply, and the electric charges in the condenser are discharged to the capillary in the tube after closing the ignitron. During the discharge, weakly ionized plasma forms on the inner and outer sides of a capillary. In the present work, the pump evacuates air from the tube with a pressure of about 1 mPa, and a demountable capillary was developed in order to measure x-ray spectra according to changes in the capillary length. In this capillary, the anode (target) and cathode elements can be changed corresponding to the objectives. The capillary diameter is 2.0 mm, and the length is adjusted from 1 to 50 mm. When a capillary with aluminum anode and cathode electrodes was employed, both the cathode voltage and the discharge current almost displayed damped oscillations. The peak values of the voltage and current increased when the charging voltage was increased, and their maximum values were -11.5 kV and 4.7 kA, respectively. The x-ray durations observed by a 1.6 μm aluminum filter were less than 30 μs. In the spectrum measurement, we observed orderly multi-line spectra. The line photon energies seldom varied according to changes in the condenser charging voltage and to changes in the electrode element. The line number decreased with corresponding decreases in the capillary length.

Computerized nailfold video capillaroscopy--a new tool for assessment of Raynaud's phenomenon.

PubMed

Anderson, Marina E; Allen, P Danny; Moore, Tonia; Hillier, Val; Taylor, Christopher J; Herrick, Ariane L

2005-05-01

To develop a computer based nailfold video capillaroscopy system with enhanced image quality and to assess its disease-subgroup resolving power in patients with primary and secondary Raynaud's phenomenon (RP). Using frame registration software, digitized video images from the microscope were combined to form a panoramic mosaic of the nailfold. Capillary dimensions (apex, arterial, venous, and total width) and density were measured onscreen. Significantly, the new system could guarantee analysis of the same set of capillaries by 2 observers. Forty-eight healthy control subjects, 21 patients with primary RP, 40 patients with limited cutaneous systemic sclerosis (lcSSc), and 11 patients with diffuse cutaneous SSc (dcSSc) were studied. Intra- and interobserver variability were calculated in a subset of 30 subjects. The number of loops/mm was significantly lower, and all 4 capillary dimensions significantly greater, in SSc patients versus controls plus primary RP patients (p < 0.001 for all measures). When comparing control (+ primary RP) patients with SSc patients (lcSSc + dcSSc) the most powerful discriminator was found to be the number of loops/mm. Results for intra- and interobserver reproducibility showed that the limits of agreement were closer when both observers measured the same capillaries. The key feature of the newly developed system is that it improves reproducibility of nailfold capillary measurements by allowing reidentification of the same capillaries by different observers. By allowing access to previous measurements, the new system should improve reliability in longitudinal studies, and therefore has the potential of being a valuable outcome measure of microvessel disease/involvement in clinical trials of scleroderma spectrum disorders.

On-line DNA analysis system with rapid thermal cycling

DOEpatents

Swerdlow, Harold P.; Wittwer, Carl T.

1999-01-01

An apparatus particularly suited for subjecting biological samples to any necessary sample preparation tasks, subjecting the sample to rapid thermal cycling, and then subjecting the sample to subsequent on-line analysis using one or more of a number of analytical techniques. The apparatus includes a chromatography device including an injection means, a chromatography pump, and a chromatography column. In addition, the apparatus also contains a capillary electrophoresis device consisting of a capillary electrophoresis column with an inlet and outlet end, a means of injection, and means of applying a high voltage to cause the differential migration of species of interest through the capillary column. Effluent from the liquid chromatography column passes over the inlet end of the capillary electrophoresis column through a tee structure and when the loading of the capillary electrophoresis column is desired, a voltage supply is activated at a precise voltage and polarity over a specific duration to cause sample species to be diverted from the flowing stream to the capillary electrophoresis column. A laser induced fluorescence detector preferably is used to analyze the products separated while in the electrophoresis column.

On-line DNA analysis system with rapid thermal cycling

DOEpatents

Swerdlow, H.P.; Wittwer, C.T.

1999-08-10

This application describes an apparatus particularly suited for subjecting biological samples to any necessary sample preparation tasks, subjecting the sample to rapid thermal cycling, and then subjecting the sample to subsequent on-line analysis using one or more of a number of analytical techniques. The apparatus includes a chromatography device including an injection means, a chromatography pump, and a chromatography column. In addition, the apparatus also contains a capillary electrophoresis device consisting of a capillary electrophoresis column with an inlet and outlet end, a means of injection, and means of applying a high voltage to cause the differential migration of species of interest through the capillary column. Effluent from the liquid chromatography column passes over the inlet end of the capillary electrophoresis column through a tee structure and when the loading of the capillary electrophoresis column is desired, a voltage supply is activated at a precise voltage and polarity over a specific duration to cause sample species to be diverted from the flowing stream to the capillary electrophoresis column. A laser induced fluorescence detector preferably is used to analyze the products separated while in the electrophoresis column. 6 figs.

Nailfold Capillaroscopy of Fingers and Toes - Variations of Normal.

PubMed

Lambova, Sevdalina Nikolova; Muller-Ladner, Ulf

2018-04-20

Nailfold capillaroscopy is the only method for morphological assessment of nutritive capillaries. The literature data about capillaroscopic findings in healthy individuals are scarce. To evaluate and compare the capillaroscopic findings of fingers and toes in healthy subjects. 22 healthy individuals were included in the study. Capillaroscopic examination was performed with videocapillaroscope Videocap 3.0 (DS Medica). Exclusion criteria were as follows: history of vasospasm, presence of accompanying diseases, taking any medications, arterial hypertension in first degree relatives, overweight or obesity (body mass index > 25kg/m2) and presence of chronic arterial or venous insufficiency. Poor visibility of nailfold capillaries was found significantly more frequently in the toes (22.7%, 5/22) as compared with fingers (0/22). Slight irregularities in capillary distribution and orientation to their parallel axis were significantly more common in the toes (31.8%, 7/22) as compared with fingers (9%, 2/22), (p<0.05). The mean diameter of the arterial (0.012±0.002mm) and the venous limb (0.017±0.002mm) of the toes did not differ significantly as compared to the respective parameters in the fingers (0.013±0.002mm for the arterial limb, p=0.46 and 0.018±0.002mm for the venous limb, p=0.25). The mean capillary density also did not differ significantly in the fingers and toes. The mean capillary length of the toes (0.165±0.096mm) was shorter as compared with hands (0.220±0.079mm), but the difference was not statistically significant (p=0.37). Presence of tortuous capillaries (>10%) was found significantly more often in the toes (12/22) as compared with fingers (6/22, χ2=6.769, p<0.05). Short capillary loops (length<100µm) were observed significantly more often in the toes (11/22 - toes, 1/22 - fingers, χ2=14.666, p<0.05). Capillaroscopic examination of the toes shows some differences as compared to those of the fingers such as greater number of cases with poor visibility and slight irregularities of distribution, greater number of shorter capillaries and increased tortuosity, which might be related to the thicker epidermis of the toes and increased capillary pressure due to gravity. The values of the major capillaroscopic parameters such as capillary diameters and capillary density in fingers and toes do not differ significantly. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

A portable dermatoscope for easy, rapid examination of periungual nailfold capillary changes in patients with systemic sclerosis.

PubMed

Muroi, Eiji; Hara, Toshihide; Yanaba, Koichi; Ogawa, Fumihide; Yoshizaki, Ayumi; Takenaka, Motoi; Shimizu, Kazuhiro; Sato, Shinichi

2011-12-01

Microvascular lesions are a predominant feature in systemic sclerosis (SSc) and seem to play a central pathogenic role. The presence of nailfold capillary abnormalities is useful in diagnosing SSc. Capillaroscopy, however, usually requires special equipment and may be time consuming. Dermatoscope has been presented as a new diagnostic tool for quick and efficient examination of nailfold capillaries for circumstances when standard microscope equipment is not available. To assess the practical utility of dermatoscope for assessment of capillary morphology in patients with SSc, 83 Japanese patients with SSc (68 women, 15 men) and 68 healthy controls were examined in the study. Twenty-one patients (16 women, 5 men) had diffuse cutaneous SSc and 62 (52 women, 10 men) had limited cutaneous SSc. Enlarged capillaries and hemorrhages were evaluated in all 10 fingers with either naked eyes or DermLite(®) DL100 dermatoscope. Enlarged capillaries and hemorrhages were significantly more frequently detected with dermatoscope than without it. These findings were observed most frequently in the fourth finger. The presence of two or more enlarged capillaries in one or more fingers showed 83.1% sensitivity and 100% specificity for SSc. Among patients with SSc with anti-topoisomerase I antibody, the disease duration correlated negatively with the dermatoscopic number of enlarged capillaries and hemorrhages. Dermatoscope allows the easy and rapid identification of capillary nailfold morphological changes in SSc and should be routinely used for diagnosing SSc.

Qualitative and quantitative assessment of nailfold capillaries by capillaroscopy in healthy volunteers.

PubMed

Hoerth, Christian; Kundi, Michael; Katzenschlager, Reinhold; Hirschl, Mirko

2012-01-01

Nailfold capillaroscopy (NVC) is a diagnostic tool particularly useful in the differential diagnosis of rheumatic and connective tissue diseases. Although successfully applied since many years, little is known about prevalence and distribution of NVC changes in healthy individuals. NVC was performed in 120 individuals (57 men and 63 women; age 18 to 70 years) randomly selected according to predefined age and sex strata. Diseases associated with NVC changes were excluded. The nailfolds of eight fingers were assessed according to standardized procedures. A scoring system was developed based on the distribution of the number of morphologically deviating capillaries, microhaemorrhages, and capillary density. Only 18 individuals (15 %) had no deviation in morphology, haemorrhages, or capillary density on any finger. Overall 67 % had morphological changes, 48 % had microhaemorrhages, and 40 % of volunteers below 40 years of age and 18 % above age 40 had less than 8 capillaries/mm. Among morphological changes tortous (43 %), ramified (47 %), and bushy capillaries (27 %) were the most frequently altered capillary types. A semiquantitative scoring system was developed in such a way that a score above 1 indicates an extreme position (above the 90th percentile) in the distribution of scores among healthy individuals. Altered capillaries occur frequently among healthy individuals and should be interpreted as normal unless a suspicious increase in their frequency is determined by reference to the scoring system. Megacapillaries and diffuse loss of capillaries were not found and seem to be of specific diagnostic value.

Quantifying retinal microvascular changes in uveitis using spectral domain optical coherence tomography angiography (SD-OCTA)

PubMed Central

Kim, Alice Y.; Rodger, Damien C.; Shahidzadeh, Anoush; Chu, Zhongdi; Koulisis, Nicole; Burkemper, Bruce; Jiang, Xuejuan; Pepple, Kathryn L.; Wang, Ruikang K.; Puliafito, Carmen A.; Rao, Narsing A.; Kashani, Amir H.

2016-01-01

Purpose To quantify retinal capillary density and morphology in uveitis using SD-OCTA. Design Cross-sectional, observational study Methods Healthy and uveitic subjects were recruited from two tertiary care eye centers. Prototype SD-OCTA devices (Cirrus, Carl Zeiss Meditec, Inc., Dublin, CA) were used to generate 3×3 mm2 OCTA images centered on the fovea. Subjects were placed into 3 groups based on the type of optical microangiography (OMAG) algorithm used for image processing (intensity-and/or phase) and type of retinal segmentation (automatic or manual). A semi-automated method was used to calculate skeleton density (SD), vessel density (VD), fractal dimension (FD), and vessel diameter index (VDI). Retinal vasculature was assessed in the superficial retinal layer (SRL), deep retinal layer (DRL), and non-segmented retinal layer (NS-RL). A generalized estimating equations model was used to analyze associations between the OCTA measures and disease status within each retinal layer. A P value < 0.05 was accepted as significant. Reproducibility and repeatability were assessed using the Intraclass Correlation Coefficient (ICC). Results The SD, VD, and FD of the parafoveal capillaries were lower in uveitic eyes compared to healthy eyes in all retinal segments. In addition, SD and VD were significantly lower in the DRL of subjects with uveitic macular edema. There was no correlation in any capillary parameters and anatomic classification of uveitis. Conclusions Quantitative analysis of parafoveal capillary density and morphology in uveitis demonstrates significantly lower capillary density and complexity. SD-OCTA algorithms are robust enough to detect these changes and can provide a novel diagnostic index of disease for uveitis subjects. PMID:27594138

X-ray Microtomography of Intermittency in Multiphase Flow at Steady State Using a Differential Imaging Method

NASA Astrophysics Data System (ADS)

Gao, Ying; Lin, Qingyang; Bijeljic, Branko; Blunt, Martin J.

2017-12-01

We imaged the steady state flow of brine and decane in Bentheimer sandstone. We devised an experimental method based on differential imaging to examine how flow rate impacts impact the pore-scale distribution of fluids during coinjection. This allows us to elucidate flow regimes (connected, or breakup of the nonwetting phase pathways) for a range of fractional flows at two capillary numbers, Ca, namely 3.0 × 10-7 and 7.5 × 10-6. At the lower Ca, for a fixed fractional flow, the two phases appear to flow in connected unchanging subnetworks of the pore space, consistent with conventional theory. At the higher Ca, we observed that a significant fraction of the pore space contained sometimes oil and sometimes brine during the 1 h scan: this intermittent occupancy, which was interpreted as regions of the pore space that contained both fluid phases for some time, is necessary to explain the flow and dynamic connectivity of the oil phase; pathways of always oil-filled portions of the void space did not span the core. This phase was segmented from the differential image between the 30 wt % KI brine image and the scans taken at each fractional flow. Using the grey scale histogram distribution of the raw images, the oil proportion in the intermittent phase was calculated. The pressure drops at each fractional flow at low and high flow rates were measured by high-precision differential pressure sensors. The relative permeabilities and fractional flow obtained by our experiment at the mm-scale compare well with data from the literature on cm-scale samples.

Visualization and contractile activity of cochlear pericytes in the capillaries of the spiral ligament.

PubMed

Dai, Min; Nuttall, Alfred; Yang, Yue; Shi, Xiaorui

2009-08-01

Pericytes, mural cells located on microvessels, are considered to play an important role in the formation of the vasculature and the regulation of local blood flow in some organs. Little is known about the physiology of cochlear pericytes. In order to investigate the function of cochlear pericytes, we developed a method to visualize cochlear pericytes using diaminofluorescein-2 diacetate (DAF-2DA) and intravital fluorescence microscopy. This method can permit the study of the effect of vasoactive agents on pericytes under the in vivo and normal physiological condition. The specificity of the labeling method was verified by the immunofluorescence labeling of pericyte maker proteins such as desmin, neural proteoglycan (NG2), and thymocyte differentiation antigen 1 (Thy-1). Superfused K(+) and Ca(2+) to the cochlear lateral wall resulted in localized constriction of capillaries at pericyte locations both in vivo and in vitro, while there was no obvious change in cochlear capillary diameters with application of the adrenergic neurotransmitter noradrenaline. The method could be an effective way to visualize cochlear pericytes and microvessels and study lateral wall vascular physiology. Moreover, we demonstrate for the first time that cochlear pericytes have contractility, which may be important for regulation of cochlear blood flow.

Short-term reversibility of ultrastructural changes in pulmonary capillaries caused by stress failure

NASA Technical Reports Server (NTRS)

Elliott, A. R.; Fu, Z.; Tsukimoto, K.; Prediletto, R.; Mathieu-Costello, O.; West, J. B.

1992-01-01

We previously showed that when the pulmonary capillaries in anesthetized rabbits are exposed to a transmural pressure (Ptm) of approximately 40 mmHg, stress failure of the walls occurs with disruption of the capillary endothelium, alveolar epithelium, or sometimes all layers. The present study was designed to determine whether some of the ultrastructural changes are rapidly reversible when the capillary pressure is reduced. To test this, the Ptm was raised to 52.5 cmH2O for 1 min of blood perfusion and then reduced to 12.5 cmH2O for 3 min of saline-dextran perfusion, followed by intravascular fixation at the same pressure. In another group of animals, the pressure was elevated for 1 min of blood and 3 min of saline-dextran before being reduced. The results were compared with previous studies in which the capillary pressures were maintained elevated at 52.5 cmH2O during the entire procedure. Control studies were also done at sustained low pressures. The results showed that the number of endothelial and epithelial breaks per millimeter and the total fraction area of the breaks were reduced when the pressure was lowered. For example, the number of endothelial breaks per millimeter decreased from 7.1 +/- 2.1 to 2.4 +/- 0.7, and the number of epithelial breaks per millimeter fell from 11.4 +/- 3.7 to 3.4 +/- 0.7. There was evidence that the breaks that closed were those that were initially small and were associated with an intact basement membrane. The results suggest that cells can move along their underlying matrix by rapid disengagement and reattachment of cell adhesion molecules, causing breaks to open or close within minutes.(ABSTRACT TRUNCATED AT 250 WORDS).

Cigarette smoke directly impairs skeletal muscle function through capillary regression and altered myofibre calcium kinetics in mice.

PubMed

Nogueira, Leonardo; Trisko, Breanna M; Lima-Rosa, Frederico L; Jackson, Jason; Lund-Palau, Helena; Yamaguchi, Masahiro; Breen, Ellen C

2018-05-23

Cigarette smoke components directly alter muscle fatigue resistance and intracellular muscle fibre Ca 2+ handling independent of a change in lung structure. Changes in muscle vascular structure are associated with a depletion of satellite cells. Sarcoplasmic reticulum Ca 2+ uptake is substantially impaired in myofibres during fatiguing contractions in mice treated with cigarette smoke extract. Cigarette smokers exhibit exercise intolerance before a decline in respiratory function. In the present study, the direct effects of cigarette smoke on limb muscle function were tested by comparing cigarette smoke delivered to mice by weekly injections of cigarette smoke extract (CSE), or nose-only exposure (CS) 5 days each week, for 8 weeks. Cigarette smoke delivered by either route did not alter pulmonary airspace size. Muscle fatigue measured in situ was 50% lower in the CSE and CS groups than in control. This was accompanied by 34% and 22% decreases in soleus capillary-to-fibre ratio of the CSE and CS groups, respectively, and a trend for fewer skeletal muscle actin-positive arterioles (P = 0.07). In addition, fewer quiescent satellite cells (Nes+Pax7+) were associated with soleus fibres in mice with skeletal myofibre VEGF gene deletion (decreased 47%) and CS exposed (decreased 73%) than with control fibres. Contractile properties of isolated extensor digitorum longus and soleus muscles were impaired. In flexor digitorum brevis myofibres isolated from CSE mice, fatigue resistance was diminished by 43% compared to control and CS myofibres, and this was accompanied by a pronounced slowing in relaxation, an increase in intracellular Ca 2+ accumulation, and a slowing in sarcoplasmic reticulum Ca 2+ uptake. These data suggest that cigarette smoke components may impair hindlimb muscle vascular structure, fatigue resistance and myofibre calcium handling, and these changes ultimately affect contractile efficiency of locomotor muscles independent of a change in lung function. © 2018 The Authors. The Journal of Physiology © 2018 The Physiological Society.

Diadenosine polyphosphates as antagonists of the endogenous P2Y1 receptor in rat brain capillary endothelial cells of the B7 and B10 clones

PubMed Central

Vigne, Paul; Breittmayer, Jean Philippe; Frelin, Christian

2000-01-01

Diadenosine polyphosphates (ApnAs, n=2–7) are considered as stress mediators in the cardiovascular system. They act both via identified P2 purinoceptors and via yet to be characterized receptors. This study analyses the actions of ApnAs in clones of rat brain capillary endothelial cells that express P2Y1 receptors (B10 cells) or both P2Y1 and P2Y2 receptors (B7 cells).B10 cells responded to Ap3A with rises in intracellular Ca2+ concentration ([Ca2+]i). This response was prevented by adenosine-3′-phosphate-5′-phosphate, an antagonist of P2Y1 receptors. It was largely suppressed by a treatment with apyrase VII or with creatine phosphokinase/creatine phosphate to degrade contaminating ADP.ApnAs inhibited ADP induced increases in [Ca2+]i mediated by P2Y1 receptors by shifting ADP concentration-response curves to larger concentrations. Apparent Ki values were estimated to be 6 μM for Ap4A, 10 μM for Ap5A and 47 μM for Ap6A. Ap2A and Ap3A were much less active.ApnAs were neither agonists nor antagonists of the endogenous P2Y2 receptor in B7 cells.ApnAs are neither agonists nor antagonists of the Gi-coupled, ADP receptor in B10 cells.The results suggest that most actions of ApnAs in B7 and B10 cells can be accounted for by endogenous P2Y1 receptors. Ap4A, Ap5A and Ap6A are specific antagonists of endogenous Ca2+-coupled P2Y1 receptors. PMID:10742308

Capillary electrophoresis of chitooligosaccharides in acidic solution: simple determination using a quaternary-ammonium-modified column and indirect photometric detection with crystal violet.

PubMed

Hattori, Toshiaki; Anraku, Nobuhiro; Kato, Ryo

2010-02-01

Five chitosan oligosaccharides were separated in acidic aqueous solution by capillary electrophoresis (CE) with indirect photometric detection using a positively coated capillary. Electrophoretic mobility of the chitooligosaccharides (COSs) depended on the number of monomer units in acidic aqueous solution, similar to other polyelectrolyte oligomers. The separation was developed in nitric acid aqueous solution at pH 3.0 with 1 mM Crystal Violet, using a capillary positively coated with N-trimethoxypropyl-N,N,N-trimethylammonium chloride. The limit of the detection for chitooligosaccharides with two to six saccharide chains was less than 5 microM. CE determination of an enzymatically hydrolyzed COS agreed with results from HPLC. 2009 Elsevier B.V. All rights reserved.

Viscosity of particulate soap films: approaching the jamming of 2D capillary suspensions.

PubMed

Timounay, Yousra; Rouyer, Florence

2017-05-14

We compute the effective viscosity of particulate soap films thanks to local velocity fields obtained by Particle Image Velocimetry (PIV) during film retraction experiments. We identify the jamming of these 2D capillary suspensions at a critical particle surface fraction (≃0.84) where effective viscosity diverges. Pair correlation function and number of neighbors in contact or close to contact reveal the cohesive nature of this 2D capillary granular media. The experimental 2D dynamic viscosities can be predicted by a model considering viscous dissipation at the liquid interfaces induced by the motion of individual particles.

Thermal dissociation of ions limits the degree of the gas-phase H/D exchange at the atmospheric pressure.

PubMed

Kostyukevich, Y; Kononikhin, A; Popov, I; Nikolaev, E

2017-04-01

We present the application of the extended desolvating capillaries for increasing the degree of the gas-phase hydrogen/deuterium exchange reaction at atmospheric pressure. The use of the extended capillaries results in the increase of the time that ions spend in the high pressure region, what leads to the significant improvement of the efficiency of the reaction. For the small protein ubiquitin, it was observed that for the same temperature, the number of exchanges increases with the decrease of the charge state so that the lowest charge state can exchange twice the number of hydrogen than the highest one. With the increase of the temperature, the difference decreases, and eventually, the number of exchanges equalizes for all charge states. The value of this temperature and the corresponding number of exchanges depend on the geometric parameters of the capillary. Further increase of the temperature leads to the thermal dissociation of the protein ion. The observed b/y fragments are identical to those produced by collision-induced dissociation performed in the ion trap. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Comparisons Between Histology and Optical Coherence Tomography Angiography of the Periarterial Capillary-Free Zone.

PubMed

Balaratnasingam, Chandrakumar; An, Dong; Sakurada, Yoichi; Lee, Cecilia S; Lee, Aaron Y; McAllister, Ian L; Freund, K Bailey; Sarunic, Marinko; Yu, Dao-Yi

2018-05-01

To use the capillary-free zone along retinal arteries, a physiologic area of superficial avascularization, as an anatomic paradigm to investigate the reliability of optical coherence tomography angiography (OCTA) for visualizing the deep retinal circulation. Validity analysis and laboratory investigation. Five normal human donor eyes (mean age 69.8 years) were perfusion-labeled with endothelial antibodies and the capillary networks of the perifovea were visualized using confocal scanning laser microscopy. Regions of the capillary-free zone along the retinal artery were imaged using OCTA in 16 normal subjects (age range 24-51 years). Then, 3 × 3-mm scans were acquired using the RTVue XR Avanti (ver. 2016.1.0.26; Optovue, Inc, Fremont, California, USA), PLEX Elite 9000 (ver. 1.5.0.15909; Zeiss Meditec, Inc, Dublin, California, USA), Heidelberg Spectralis OCT2 (Family acquisition module 6.7.21.0; Heidelberg Engineering, Heidelberg, Germany), and DRI-OCT Triton (Ver. 1.1.1; Topcon Corp, Tokyo, Japan). Images of the superficial plexus, deep vascular plexus, and a slab containing all vascular plexuses were generated using manufacturer-recommended default settings. Comparisons between histology and OCTA were performed. Histologic analysis revealed that the capillary-free zone along the retinal artery was confined to the plane of the superficial capillary plexus and did not include the intermediate and deep capillary plexuses. Images derived from OCTA instruments demonstrated a prominent capillary-free zone along the retinal artery in slabs of the superficial plexus, deep plexus, and all capillary plexuses. The number of deep retinal capillaries seen in the capillary-free zone was significantly greater on histology than on OCTA (P < .001). Using the capillary-free zone as an anatomic paradigm, we show that the deep vascular beds of the retina are not completely visualized using OCTA. This may be a limitation of current OCTA techniques. Copyright © 2018 Elsevier Inc. All rights reserved.

Cell adhesion during bullet motion in capillaries.

PubMed

Takeishi, Naoki; Imai, Yohsuke; Ishida, Shunichi; Omori, Toshihiro; Kamm, Roger D; Ishikawa, Takuji

2016-08-01

A numerical analysis is presented of cell adhesion in capillaries whose diameter is comparable to or smaller than that of the cell. In contrast to a large number of previous efforts on leukocyte and tumor cell rolling, much is still unknown about cell motion in capillaries. The solid and fluid mechanics of a cell in flow was coupled with a slip bond model of ligand-receptor interactions. When the size of a capillary was reduced, the cell always transitioned to "bullet-like" motion, with a consequent decrease in the velocity of the cell. A state diagram was obtained for various values of capillary diameter and receptor density. We found that bullet motion enables firm adhesion of a cell to the capillary wall even for a weak ligand-receptor binding. We also quantified effects of various parameters, including the dissociation rate constant, the spring constant, and the reactive compliance on the characteristics of cell motion. Our results suggest that even under the interaction between P-selectin glycoprotein ligand-1 (PSGL-1) and P-selectin, which is mainly responsible for leukocyte rolling, a cell is able to show firm adhesion in a small capillary. These findings may help in understanding such phenomena as leukocyte plugging and cancer metastasis. Copyright © 2016 the American Physiological Society.

Computer Simulation of Breast Cancer Screening

DTIC Science & Technology

2001-07-01

21. Tompkins PA, Abreu CC, Carroll FE, Xiao therapeutic medical physics. Med Phys 14. Gentry JR, DeWerd LA. TLD measure- QF, MacDonald CA. Use of...capillary op- 1996; 23:1997-2005. ments of in vivo mammographic expo- tics as a beam intensifier for a Compton 28. Hammerstein GR, Miller DW, White DR...cm), and was only poorly correlated thicker slices. with breast thickness (r2 0.159). The For comparison images and dosimetry , magnification factor

Science of Decision Making: A Data-Modeling Approach

DTIC Science & Technology

2013-10-01

were separated on a capillary column using the Dionex UltiMate 3000 (Sunnyvale, CA). The resolved peptides were then sprayed into a linear ion trap...database (3–5). These algorithms assign a peptide sequence, along with a matching score of the experimental ion product mass spectrum, to a theoretical ion ...Bacterial Sample Processing Samples were prepared for liquid chromatography (LC) tandem MS (LC– MS/MS) in a similar manner to that previously reported

Divalent ion block of inward rectifier current in human capillary endothelial cells and effects on resting membrane potential

PubMed Central

Jow, Flora; Numann, Randy

1998-01-01

Cultured human capillary endothelial cells (HCEC) contain a large inward rectifier current, IK(IR), that can be abolished by removing external K+ or by adding 50 μm Ba2+.We show that IK(IR) is responsible for maintaining the hyperpolarized potential (−60.6 ± 0.5 mV, n = 83) of HCEC. Blocking IK(IR) with 50 μm Ba2+ shifts the zero current level and depolarizes HCEC by 36.5 ± 1.3 mV (n = 4).Increasing external Ca2+ concentration ([Ca2+]o) from 0.5 to 7 mm reduces the magnitude of IK(IR) by 36.5 ± 2.3 % (n = 5) and depolarizes the cells by 10.33 ± 2.4 mV (n = 3), whereas decreasing [Ca2+]o from 1.8 to 0.5 mm increases the amplitude of IK(IR) by 6.9 ± 1.9 % (n = 4). The relationship between [Ca2+]o and the percentage block of IK(IR) gives a Kd value of 5.4 ± 0.6 mm at −120 mV.IK(IR) is also blocked by other divalent ions, with Ba2+ >> Sr2+ > Mg2+ > Mn2+= Ca2+, and the block of peak current at −120 mV being 85.3 ± 3.2 % (n = 5) for 50 μm Ba2+, 62.9 ± 2.2 % (n = 5) for 5 mm Sr2+, 40.7 ± 2.5 % (n = 9) for 5 mm Mg2+, 33.4 ± 2.1 % (n = 5) for 5 mm Mn2+ and 32.9 ± 2.1 % (n = 5) for 5 mm Ca2+.The voltage dependence of Sr2+ block of peak IK(IR) occurred with a Kd value of 1.0 ± 0.09 mm for −140 mV, 1.9 ± 0.16 mm for −130 mV, 3.1 ± 0.28 mm for −120 mV, 4.6 ± 0.34 mm for −110 mV and 6.4 ± 0.5 mm for −100 mV (n = 5), with a calculated electrical distance (δ) of 0.44 from the outside. PMID:9729622

Simultaneous determination of rifabutin and human serum albumin in pharmaceutical formulations by capillary electrophoresis.

PubMed

Ermolenko, Yu; Anshakova, A; Osipova, N; Kamentsev, M; Maksimenko, O; Balabanyan, V; Gelperina, S

Capillary zone electrophoresis (CZE) was used for determination of rifabutin (RFB), an anti-tuberculosis antibiotic drug, in various pharmaceutical formulations. Apart from that, simultaneous determination of RFB and human serum albumin (HSA) was performed. Electrophoretic behaviour of RFB was examined at various pH levels. CE conditions: a quartz capillary tube (internal diameter 75mm, effective length 50cm, total length 60cm), the capillary temperature was 25°С, the voltage applied to the capillary tube was +20kV, the UV detection wavelength was 214nm, hydrodynamic injection of the sample was performed at 30mbar for 5s, tetraborate buffer solution (0.01М, рН9.2). The obtained results are characterized by high efficiency (number of theoretical plates up to 260,000) and sufficient sensitivity (LOQ starting from 0.02μg/ml for RFB). The obtained data are in good accord with both HPLC results (for RFB) and spectrophotometry (for HSA). Copyright © 2017 Elsevier Inc. All rights reserved.

A neuron-in-capillary platform for facile collection and mass spectrometric characterization of a secreted neuropeptide

PubMed Central

Lee, Chang Young; Fan, Yi; Rubakhin, Stanislav S.; Yoon, Sook; Sweedler, Jonathan V.

2016-01-01

The integration of microfluidic devices—which efficiently handle small liquid volumes—with separations/mass spectrometry (MS) is an effective approach for profiling the neurochemistry occurring in selected neurons. Interfacing the microfluidic cell culture to the mass spectrometer is challenging because of geometric and scaling issues. Here we demonstrate the hyphenation of a neuron-in-capillary platform to a solid phase extraction device and off-line MS. A primary neuronal culture of Aplysia californica neurons was established directly inside a cylindrical polyimide capillary. The approach also uses a particle-embedded monolith to condition neuropeptide releasates collected from several Aplysia neurons cultured in the capillary, with the subsequent characterization of released peptides via MS. This system presents a number of advances compared to more traditional microfluidic devices fabricated with polydimethylsiloxane. These include low cost, easy access to cell culture, rigidity, ease of transport, and minimal fluid handling. The cylindrical geometry of the platform allows convenient interface with a wide range of analytical tools that utilize capillary columns. PMID:27245782

Free-surface entrainment into a rimming flow containing surfactants

NASA Astrophysics Data System (ADS)

Thoroddsen, S. T.; Tan, Y.-K.

2004-02-01

We study experimentally the free-surface entrainment of tubes into a steady rimming flow formed inside a partially filled horizontally rotating cylinder. The liquid consists of a glycerin-water mixture containing surfactants (fatty acids). The phenomenon does not occur without the surfactants and the details are sensitive to their concentration. The entrainment of numerous closely spaced air tubes and/or surfactant columns can start intermittently along a two-dimensional stagnation line, but is usually associated with the appearance of an axially periodic vortex structure, the so-called shark teeth, which fixes the spanwise location of these tubes. The number of tubes is governed by the three-dimensional shape of the free surface, reducing from more than 10 to only two in each trough, as the rotation rate is increased. The tubes vary in diameter from 10-30 μm and can extend hundreds of diameters into the liquid layer before breaking up into a continuous stream of bubbles and/or drops. The tubes are driven through the stagnation line by the strong viscous shear and are stretched in the downstream direction. The entrainment starts when the Capillary number Ca=μωR/σ≃0.4.

Measurement and characterization of lift forces on drops and bubbles in microchannels

NASA Astrophysics Data System (ADS)

Stan, Claudiu; Guglielmini, Laura; Ellerbee, Audrey; Caviezel, Daniel; Whitesides, George; Stone, Howard

2013-11-01

The transverse motion of drops and bubbles within liquids flowing in pipes and channels is determined by the combination of several types of hydrodynamic lift forces with external forces. In microfluidic channels, lift forces have been used to position and sort particles with high efficiency and high accuracy. We measured lift forces on drops and bubbles and discriminated between different lift mechanisms under conditions characterized by low particle capillary numbers (0.0003 < CaP < 0.3) and low particle Reynolds numbers (0.0001 < ReP < 0.1). The measured lift forces were often much larger (up to a factor of 1000) than the predictions of analytical models of inertial and deformation-induced lift, indicating that another lift mechanism was the largest contributor to the total lift force. The systems we investigated exhibited either (i) a deformation-induced lift force enhanced by confinement effects, or (ii) a lift force for which to our best knowledge is based on physicochemical effects at the interfaces of drops and bubbles. We will present new experimental data that supports a dynamic interfacial mechanism for the second type of lift force, and discuss possible avenues for creating an analytical model for it.

Numerical studies of film formation in context of steel coating

NASA Astrophysics Data System (ADS)

Aniszewski, Wojciech; Zaleski, Stephane; Popinet, Stephane

2017-11-01

In this work, we present a detailed example of numerical study of film formation in the context of metal coating. Liquid metal is drawn from a reservoir onto a retracting solid sheet, forming a coating film characterized by phenomena such as longitudinal thickness variation (in 3D) or waves akin to that predicted by Kapitza and Kapitza (visible in two dimensions as well). While the industry standard configuration for Zinc coating is marked by coexistence of medium Capillary number (Ca = 0.03) and film Reynolds number above 1000, we present also parametric studies in order to establish more clearly to what degree does the numerical method influence film regimes obtained in the target configuration. The simulations have been performed using Basilisk, a grid-adapting, strongly optimized code derived from Gerris . Mesh adaptation allows for arbitrary precision in relevant regions such as the contact line or the meniscus, while a coarse grid is applied elsewhere. This adaptation strategy, as the results indicate, is the only realistic approach for numerical method to cover the wide range of necessary scales from the predicted film thickness (hundreds of microns) to the domain size (meters).

Prior poliomyelitis-reduced capillary supply and metabolic enzyme content in hypertrophic slow-twitch (type I) muscle fibres.

PubMed Central

Borg, K; Henriksson, J

1991-01-01

Capillary supply and oxidative and glycolytic enzyme activities were determined in muscle biopsies from the tibialis anterior muscle in six prior polio patients and a control group. The polio patients, who had paresis and atrophy, but were able to walk normally by making maximal use of all remaining anterior tibial motor units, showed type I (slow-twitch) muscle fibre predominance with a mean (SD) of 98 (2%) type I fibres versus 81 (8)% in the controls (p less than 0.01) and muscle fibre hypertrophy, the average type I fibre cross-sectional area being 108% (p less than 0.005) larger than in the controls. The number of capillaries per muscle fibre was not significantly different from that in the control group, but with the increased muscle fibre area in the polio patients, the capillary density was significantly lower. The number of capillaries in contact with type I fibres relative to fibre area was 40% lower in the patients than in the controls (p less than 0.005). The levels of citrate synthase and phosphofructokinase were significantly lower (38% and 33%, respectively, p less than 0.05) in the patients than in the controls, indicating decreased oxidative and glycolytic potentials in the muscle fibres of the polio patients. It is proposed that the abnormal high-frequency activation of all remaining motor units during each step cycle recorded in these patients constitutes a stimulus for type I muscle fibre predominance and hypertrophy but that the overall low muscle usage results in a decreased stimulation of capillary proliferation and mitochondrial enzyme synthesis. The low capillary density and decreased oxidative and glycolytic enzyme potentials might be important factors for the development of muscle weakness, fatigue and muscle pain, which are commonly occurring symptoms in patients with prior poliomyelitis. PMID:2030351

Growth of arterioles in chronically stimulated adult rat skeletal muscle.

PubMed

Hansen-Smith, F; Egginton, S; Hudlicka, O

1998-01-01

The purpose of this study was to test the hypothesis that capillary growth induced by chronic electrical stimulation of skeletal muscle is accompanied by the growth of small arterioles. Lower limb flexor muscles of Sprague-Dawley rats were stimulated by electrodes implanted in the vicinity of the peroneal nerve at 10 Hz for 8 h/d for 2 and 7 days. Cryostat sections from the proximal, middle, and distal regions of the extensor digitorum longus muscle (EDL) were fluorescently immunolabeled with alpha-smooth muscle actin (alpha SMA) and myosin heavy chain (MHC) to identify mature (alpha SMA and MHC-positive) and immature (alpha SMA-positive, MHC-negative) arterioles. The fluorescent derivative of the lectin Griffonia simplicifolia I (GSI) was used to identify all microvessels, including arterioles, capillaries, and venules. The number of vessels positive for GSI or alpha SMA surrounding muscle fibers was similar in all three muscle regions (proximal, middle, distal). The mean values +/- SEM for GSI-positive vessels from all regions were similar in control (4.3 +/- 0.07) and 2-day stimulated (4.7 +/- 0.08) but higher in 7-day stimulated muscles (6.7 +/- 0.1, p < 0.05), thus confirming the previous findings on capillary growth. A similar increase was found in the number of alpha SMA positive vessels < or = 10 microns outer diameter (1.3 +/- 0.09 versus 0.4 +/- 0.03 around muscle fibers in controls). The density of terminal arterioles (< or = 10 microns) was slightly but not significantly higher after 2 days of stimulation (19.5 +/- 4 versus 15.6 +/- 2 profiles/mm2 in control muscles) and significantly higher after 7 days (33 +/- 7). While a similar increase was observed in the density of preterminal arterioles > 10 microns (17 +/- 3 control, 22 +/- 3 at 2 days and 40 +/- 5 at 7 days), the density of MHC-positive vessels muscles stimulated for 7 days was unchanged. Seven-day stimulated muscle also had a fivefold higher density of microvessel profiles < or = 10 microns that were only partially surrounded by alpha SMA. This considerably exceeds the relative increase in the number of capillaries and thus supports the concept of arteriolar growth by transformation from capillaries. Chronic electrical stimulation results in an early increase in the number of immature (MHG-negative), but not mature (MHC-positive) arterioles, a process that accompanies the increase in capillarization. The great increase in the number of microvessels only partially covered by alpha SMA suggests arteriolization of capillaries as a contributing mechanism in this growth.

Mitochondrial carbonic anhydrase in the nervous system: expression in neuronal and glial cells.

PubMed

Ghandour, M S; Parkkila, A K; Parkkila, S; Waheed, A; Sly, W S

2000-11-01

Carbonic anhydrase (CA) V is a mitochondrial enzyme that has been reported in several tissues of the gastrointestinal tract. In liver, it participates in ureagenesis and gluconeogenesis by providing bicarbonate ions for two other mitochondrial enzymes: carbamyl phosphate synthetase I and pyruvate carboxylase. This study presents evidence of immunohistochemical localization of CA V in the rodent nervous tissue. Polyclonal rabbit antisera against a polypeptide of 17 C-terminal amino acids of rat CA V and against purified recombinant mouse isozyme were used in western blotting and immunoperoxidase stainings. Immunohistochemistry showed that CA V is expressed in astrocytes and neurons but not in oligodendrocytes, which are rich in CA II, or capillary endothelial cells, which express CA IV on their plasma face. The specificity of the immunohistochemical results was confirmed by western blotting, which identified a major 30-kDa polypeptide band of CA V in mouse cerebral cortex, hippocampus, cerebellum, spinal cord, and sciatic nerve. The expression of CA V in astrocytes and neurons suggests that this isozyme has a cell-specific, physiological role in the nervous system. In astrocytes, CA V may play an important role in gluconeogenesis by providing bicarbonate ions for the pyruvate carboxylase. The neuronal CA V could be involved in the regulation of the intramitochondrial calcium level, thus contributing to the stability of the intracellular calcium concentration. CA V may also participate in bicarbonate ion-induced GABA responses by regulating the bicarbonate homeostasis in neurons, and its inhibition could be the basis of some neurotropic effects of carbonic anhydrase inhibitors.

Hypoxic stress up-regulates Kir2.1 expression and facilitates cell proliferation in brain capillary endothelial cells.

PubMed

Yamamura, Hideto; Suzuki, Yoshiaki; Yamamura, Hisao; Asai, Kiyofumi; Imaizumi, Yuji

2016-08-05

The blood-brain barrier (BBB) is mainly composed of brain capillary endothelial cells (BCECs), astrocytes and pericytes. Brain ischemia causes hypoxic encephalopathy and damages BBB. However, it remains still unclear how hypoxia affects BCECs. In the present study, t-BBEC117 cells, an immortalized bovine brain endothelial cell line, were cultured under hypoxic conditions at 4-5% oxygen for 72 h. This hypoxic stress caused hyperpolarization of resting membrane potential. Patch-clamp recordings revealed a marked increase in Ba(2+)-sensitive inward rectifier K(+) current in t-BBEC117 cells after hypoxic culture. Western blot and real-time PCR analyses showed that Kir2.1 expression was significantly up-regulated at protein level but not at mRNA level after the hypoxic culture. Ca(2+) imaging study revealed that the hypoxic stress enhanced store-operated Ca(2+) (SOC) entry, which was significantly reduced in the presence of 100 μM Ba(2+). On the other hand, the expression of SOC channels such as Orai1, Orai2, and transient receptor potential channels was not affected by hypoxic stress. MTT assay showed that the hypoxic stress significantly enhanced t-BBEC117 cell proliferation, which was inhibited by approximately 60% in the presence of 100 μM Ba(2+). We first show here that moderate cellular stress by cultivation under hypoxic conditions hyperpolarizes membrane potential via the up-regulation of functional Kir2.1 expression and presumably enhances Ca(2+) entry, resulting in the facilitation of BCEC proliferation. These findings suggest potential roles of Kir2.1 expression in functional changes of BCECs in BBB following ischemia. Copyright © 2016 Elsevier Inc. All rights reserved.

Synthetic Capillaries to Control Microscopic Blood Flow

NASA Astrophysics Data System (ADS)

Sarveswaran, K.; Kurz, V.; Dong, Z.; Tanaka, T.; Penny, S.; Timp, G.

2016-02-01

Capillaries pervade human physiology. The mean intercapillary distance is only about 100 μm in human tissue, which indicates the extent of nutrient diffusion. In engineered tissue the lack of capillaries, along with the associated perfusion, is problematic because it leads to hypoxic stress and necrosis. However, a capillary is not easy to engineer due to its complex cytoarchitecture. Here, it is shown that it is possible to create in vitro, in about 30 min, a tubular microenvironment with an elastic modulus and porosity consistent with human tissue that functionally mimicks a bona fide capillary using “live cell lithography”(LCL) to control the type and position of cells on a composite hydrogel scaffold. Furthermore, it is established that these constructs support the forces associated with blood flow, and produce nutrient gradients similar to those measured in vivo. With LCL, capillaries can be constructed with single cell precision—no other method for tissue engineering offers such precision. Since the time required for assembly scales with the number of cells, this method is likely to be adapted first to create minimal functional units of human tissue that constitute organs, consisting of a heterogeneous population of 100-1000 cells, organized hierarchically to express a predictable function.

Synthetic Capillaries to Control Microscopic Blood Flow.

PubMed

Sarveswaran, K; Kurz, V; Dong, Z; Tanaka, T; Penny, S; Timp, G

2016-02-24

Capillaries pervade human physiology. The mean intercapillary distance is only about 100 μm in human tissue, which indicates the extent of nutrient diffusion. In engineered tissue the lack of capillaries, along with the associated perfusion, is problematic because it leads to hypoxic stress and necrosis. However, a capillary is not easy to engineer due to its complex cytoarchitecture. Here, it is shown that it is possible to create in vitro, in about 30 min, a tubular microenvironment with an elastic modulus and porosity consistent with human tissue that functionally mimicks a bona fide capillary using "live cell lithography"(LCL) to control the type and position of cells on a composite hydrogel scaffold. Furthermore, it is established that these constructs support the forces associated with blood flow, and produce nutrient gradients similar to those measured in vivo. With LCL, capillaries can be constructed with single cell precision-no other method for tissue engineering offers such precision. Since the time required for assembly scales with the number of cells, this method is likely to be adapted first to create minimal functional units of human tissue that constitute organs, consisting of a heterogeneous population of 100-1000 cells, organized hierarchically to express a predictable function.

Fast DNA sieving through submicrometer cylindrical glass capillary matrix.

PubMed

Cao, Zhen; Yobas, Levent

2014-01-07

Here, we report on DNA electrophoresis through a novel artificial sieving matrix based on the highly regular submicrometer cylindrical glass capillary segments alternatingly arranged with wells. Such round capillaries pose a higher-order confinement resulting in a lower partition coefficient and greater entropic energy barrier while limiting the driving field strength to a small fraction of the applied electric field. In return, the separation can be performed at high average field strengths (up to 1.6 kV/cm) without encountering the field-dependent loss of resolving power. This leads to fast DNA sieving as demonstrated here on the capillaries of 750 nm in diameter. The 600 bp to 21 kbp long chains are shown to resolve within 4 min after having undergone a fairly limited number of entropic barriers (128 in total). The capillary matrix also exhibits a critical field threshold below which DNA bands fail to launch, and this occurs at a considerably greater magnitude than in other matrixes. The submicrometer capillaries are batch-fabricated on silicon through a fabrication process that does not require high-resolution advanced lithography or well-controlled wafer bonding techniques to define their critical dimension.

Standardization of the capillary electrophoresis procedures Capillarys® CDT and Minicap® CDT in comparison to the IFCC reference measurement procedure.

PubMed

Schellenberg, François; Humeau, Camille

2017-06-01

CDT is at present the most relevant routinely available biological marker of alcohol use and is widely used for screening and monitoring of patients. The lack of standardization leads to specific reference intervals for each procedure. The IFCC working group devoted to CDT demonstrated that the standardization is possible using calibrators assigned to the reference measurement procedure. In this study, we compare the capillary electrophoresis (CE) techniques Capillarys® CDT and Minicap® CDT (Sebia, Lisses, France) to the reference procedure before and after standardization in 126 samples covering the range of CDT measurement. Both capillary electrophoresis procedures show a high correlation (r=0,997) with the reference procedure and the concordance correlation coefficient evaluated according to Mc Bride is "almost perfect" (>0.997 for both CE procedures). The number of results with a relative difference higher than the acceptable difference limit is only 1 for Capillarys® CDT and 5 for Minicap® CDT. These results demonstrate the efficiency of the standardization of CDT measurements for both CE techniques from Sebia, achieved using calibrators assigned to the reference measurement procedure.

Analytic theory for the selection of Saffman-Taylor fingers in the presence of thin film effects

NASA Technical Reports Server (NTRS)

Tanveer, S.

1990-01-01

The present analytic theory for the width selection of Saffman-Taylor (1958) fingers in the presence of the thin film effect establishes that, in the limit of a small capillary number and a small gap-to-width ratio, fingers whose relative width is smaller than 1/2 are possible. It is established that a fully nonlinear analysis is required for this problem in order to obtain even the correct (and rather preliminary) scaling law. The way in which the selection rule for arbitrary small capillary number is obtainable is also presented.

Single-Molecule Detection in Micron-Sized Capillaries

NASA Astrophysics Data System (ADS)

Ball, David A.; Shen, Guoqing; Davis, Lloyd M.

2004-11-01

The detection of individual molecules in solution by laser-induced fluorescence is becoming an increasingly important tool for biophysics research and biotechnology applications. In a typical single-molecule detection (SMD) experiment, diffusion is the dominant mode of transport of fluorophores through the focused laser beam. In order to more rapidly process a large number of slowly diffusing bio-molecules for applications in pharmaceutical drug discovery, a flow can be introduced within a capillary. If the flow speed is sufficient, bio-molecules will be carried through the probe volume significantly faster than by diffusion alone. Here we discuss SMD near the tip of, and in, such micron-sized capillaries, with a high numerical-aperture microscope objective used for confocal-epi-illumination along the axis of the capillary. Problems such as molecular adsorption to the glass are also addressed.

PIK3CA-associated developmental disorders exhibit distinct classes of mutations with variable expression and tissue distribution

PubMed Central

Timms, Andrew E.; Conti, Valerio; Girisha, Katta M.; Martin, Beth; Olds, Carissa; Collins, Sarah; Park, Kaylee; Carter, Melissa; Krägeloh-Mann, Inge; Chitayat, David; Parikh, Aditi Shah; Bradshaw, Rachael; Torti, Erin; Braddock, Stephen; Burke, Leah; Ghedia, Sondhya; Stephan, Mark; Stewart, Fiona; Prasad, Chitra; Napier, Melanie; Saitta, Sulagna; Straussberg, Rachel; Gabbett, Michael; O’Connor, Bridget C.; Yin, Lim Jiin; Lai, Angeline Hwei Meeng; Martin, Nicole; McKinnon, Margaret; Addor, Marie-Claude; Schwartz, Charles E.; Lanoel, Agustina; Conway, Robert L.; Devriendt, Koenraad; Tatton-Brown, Katrina; Pierpont, Mary Ella; Painter, Michael; Worgan, Lisa; Reggin, James; Hennekam, Raoul; Pritchard, Colin C.; Aracena, Mariana; Gripp, Karen W.; Cordisco, Maria; Van Esch, Hilde; Garavelli, Livia; Curry, Cynthia; Goriely, Anne; Kayserilli, Hulya; Shendure, Jay; Graham, John; Guerrini, Renzo; Dobyns, William B.

2016-01-01

Mosaicism is increasingly recognized as a cause of developmental disorders with the advent of next-generation sequencing (NGS). Mosaic mutations of PIK3CA have been associated with the widest spectrum of phenotypes associated with overgrowth and vascular malformations. We performed targeted NGS using 2 independent deep-coverage methods that utilize molecular inversion probes and amplicon sequencing in a cohort of 241 samples from 181 individuals with brain and/or body overgrowth. We identified PIK3CA mutations in 60 individuals. Several other individuals (n = 12) were identified separately to have mutations in PIK3CA by clinical targeted-panel testing (n = 6), whole-exome sequencing (n = 5), or Sanger sequencing (n = 1). Based on the clinical and molecular features, this cohort segregated into three distinct groups: (a) severe focal overgrowth due to low-level but highly activating (hotspot) mutations, (b) predominantly brain overgrowth and less severe somatic overgrowth due to less-activating mutations, and (c) intermediate phenotypes (capillary malformations with overgrowth) with intermediately activating mutations. Sixteen of 29 PIK3CA mutations were novel. We also identified constitutional PIK3CA mutations in 10 patients. Our molecular data, combined with review of the literature, show that PIK3CA-related overgrowth disorders comprise a discontinuous spectrum of disorders that correlate with the severity and distribution of mutations. PMID:27631024

Unusual effect of water vapor pressure on dehydration of dibasic calcium phosphate dihydrate.

PubMed

Kaushal, Aditya M; Vangala, Venu R; Suryanarayanan, Raj

2011-04-01

Dibasic calcium phosphate occurs as an anhydrate (DCPA; CaHPO₄) and as a dihydrate (DCPD; CaHPO₄•2H₂O). Our objective was to investigate the unusual behavior of these phases. Dibasic calcium phosphate dihydrate was dehydrated in a (i) differential scanning calorimeter (DSC) in different pan configurations; (ii) variable-temperature X-ray diffractometer (XRD) at atmospheric and under reduced pressure, and in sealed capillaries; and (iii) water vapor sorption analyzer at varying temperature and humidity conditions. Dehydration was complete by 210°C in an open DSC pan and under atmospheric pressure in the XRD. Unlike "conventional" hydrates, the dehydration of DCPD was facilitated in the presence of water vapor. Variable-temperature XRD in a sealed capillary and DSC in a hermetic pan with pinhole caused complete dehydration by 100°C and 140°C, respectively. Under reduced pressure, conversion to the anhydrate was incomplete even at 300°C. The increase in dehydration rate with increase in water vapor pressure has been explained by the Smith-Topley effect. Under "dry" conditions, a coating of poorly crystalline product is believed to form on the surface of particles and act as a barrier to further dehydration. However, in the presence of water vapor, recrystallization occurs, creating cracks and channels and facilitating continued dehydration. Copyright © 2010 Wiley-Liss, Inc.

Properties of Cement Mortar Produced from Mixed Waste Materials with Pozzolanic Characteristics.

PubMed

Yen, Chi-Liang; Tseng, Dyi-Hwa; Wu, Yue-Ze

2012-07-01

Waste materials with pozzolanic characteristics, such as sewage sludge ash (SSA), coal combustion fly ash (FA), and granulated blast furnace slag (GBS), were reused as partial cement replacements for making cement mortar in this study. Experimental results revealed that with dual replacement of cement by SSA and GBS and triple replacement by SSA, FA, and GBS at 50% of total cement replacement, the compressive strength (Sc) of the blended cement mortars at 56 days was 93.7% and 92.9% of the control cement mortar, respectively. GBS had the highest strength activity index value and could produce large amounts of CaO to enhance the pozzolanic activity of SSA/FA and form calcium silicate hydrate gels to fill the capillary pores of the cement mortar. Consequently, the Sc development of cement mortar with GBS replacement was better than that without GBS, and the total pore volume of blended cement mortars with GBS/SSA replacement was less than that with FA/SSA replacement. In the cement mortar with modified SSA and GBS at 70% of total cement replacement, the Sc at 56 days was 92.4% of the control mortar. Modifying the content of calcium in SSA also increased its pozzolanic reaction. CaCl(2) accelerated the pozzolanic activity of SSA better than lime did. Moreover, blending cement mortars with GBS/SSA replacement could generate more monosulfoaluminate to fill capillary pores.

Properties of Cement Mortar Produced from Mixed Waste Materials with Pozzolanic Characteristics

PubMed Central

Yen, Chi-Liang; Tseng, Dyi-Hwa; Wu, Yue-Ze

2012-01-01

Abstract Waste materials with pozzolanic characteristics, such as sewage sludge ash (SSA), coal combustion fly ash (FA), and granulated blast furnace slag (GBS), were reused as partial cement replacements for making cement mortar in this study. Experimental results revealed that with dual replacement of cement by SSA and GBS and triple replacement by SSA, FA, and GBS at 50% of total cement replacement, the compressive strength (Sc) of the blended cement mortars at 56 days was 93.7% and 92.9% of the control cement mortar, respectively. GBS had the highest strength activity index value and could produce large amounts of CaO to enhance the pozzolanic activity of SSA/FA and form calcium silicate hydrate gels to fill the capillary pores of the cement mortar. Consequently, the Sc development of cement mortar with GBS replacement was better than that without GBS, and the total pore volume of blended cement mortars with GBS/SSA replacement was less than that with FA/SSA replacement. In the cement mortar with modified SSA and GBS at 70% of total cement replacement, the Sc at 56 days was 92.4% of the control mortar. Modifying the content of calcium in SSA also increased its pozzolanic reaction. CaCl2 accelerated the pozzolanic activity of SSA better than lime did. Moreover, blending cement mortars with GBS/SSA replacement could generate more monosulfoaluminate to fill capillary pores. PMID:22783062

Use of microcirculatory parameters to evaluate clinical treatments of chronic venous disorder (CVD).

PubMed

Lascasas-Porto, Carmen Lucia; Milhomens, Ana Letícia M; Virgini-Magalhães, Carlos Eduardo; Fernandes, Fabiano F A; Sicuro, Fernando L; Bouskela, Eliete

2008-05-01

To evaluate changes on cutaneous microangiopathy in chronic venous disorder (CVD) after use of Cirkan [venotonic drug containing Ruscus aculeatus (plant extract), hesperidine methylchalcone (flavonoid) and vitamin C], elastic compression stockings (ECS) or no treatment for four weeks. Fifty-five female patients (85 legs), 25 to 57 years, with at least one limb classified as C2,s or C2,3,s (CEAP classification), were allocated consecutively, according to entrance order, in these three groups. Ten healthy women age-matched were also investigated. Using orthogonal polarization spectral technique (noninvasive method), measurements of functional capillary density (FCD, number of capillaries with flowing red blood cells/mm(2)), capillary morphology (CM, % of abnormal capillaries/mm(2)) and diameters (mum) of dermal papilla (DDP), capillary bulk (DCB) and capillary limb (CD) were obtained on the medial perimalleolar region and later analyzed using CapImage software. CVD patients showed significant changes on CD and CM compared to healthy subjects in agreement with our previous findings (J Vasc Surg 43:1037-1044, 2006). On Cirkan-treated patients, after 4 weeks, CD decreased on both limbs and CM improved on the left one, suggesting an amelioration of the chronic venous hypertension. No significant changes could be detected on other patient groups. These results confirm the existence of microcirculatory dysfunction in early stages of CVD, probably due to post-capillary hypertension, and further support the venotonic action of Cirkan.

Nonequilibrium capillarity effects in multiphase flow through small volume fractured porous media

NASA Astrophysics Data System (ADS)

Tang, M.; Zhan, H.; Lu, S.

2017-12-01

Analyzing and understanding the capillary pressure curves in fractured porous media is a crucial subject in a number of industrial applications, such as crude oil recovery in the fractured reservoir, CO2 sequestration in fractured brine aquifers and shale gas development. Many studies have observed the significant nonequilibrium capillarity effects in multiphase flow through porous media and proposed that conventional equilibrium capillary pressure may not accurately describe transient two-phase flow behavior under dynamical conditions. To date, only several laboratory experiments and numerical models have been conducted into investigating the characteristic of nonequilibrium capillary pressure in unfractured porous media, a clear picture of the effects of fractures on the dynamic capillary pressure in fractured porous media remains elusive. In this study, four digital porous models were built based on CT image data from ZEISS Xradia 520 Versa CT scanning, a series of direct simulations of multiphase flow in fractured porous media were carried out based on lattice Boltzmann method and three-dimensional porous models. The results show that both the aperture and orientation of the fractures have significant effects on the nonequilibrium capillary pressure coefficients and multiphase flow behaviors. The nonequilibrium capillary pressure coefficients in fractured porous media are one to two orders of magnitude lower than unfractured porous media. This study presents a new direct simulation based methodology for the detailed analysis of nonequilibrium capillary pressure in fractured porous media.

Numerical analysis of cell adhesion in capillary flow

NASA Astrophysics Data System (ADS)

Takeishi, Naoki; Imai, Yohsuke; Ishida, Shunichi; Omori, Toshihiro; Kamm, Roger; Ishikawa, Takuji

2016-11-01

Numerical simulation of cell adhesion was performed for capillaries whose diameter is comparable to or smaller than that of the cell. Despite a lot of works about leukocyte and tumor cell rolling, cell motion in capillaries has remained unclear. The solid and fluid mechanics of a cell in flow was coupled with a slip bond model of ligand-receptor interactions. When the size of a capillary was reduced, the cell always transitioned to "bullet-like" motion, with a consequent decrease in the velocity of the cell. A state diagram is obtained for various values of capillary diameter and receptor density. According to our numerical results, bullet motion enables firm adhesion of a cell to the capillary wall even for a weak ligand-receptor binding. We also quantified effects of various parameters, including the dissociation rate constant, the spring constant, and the reactive compliance on the characteristics of cell motion. Our results suggest that even under the interaction between PSGL-1 and P-selectin, which is mainly responsible for leukocyte rolling, a cell is able to show firm adhesion in a small capillary. These findings may help in understanding such phenomena as leukocyte plugging and cancer metastasis. This research was supported by JSPS KAKENHI Grant Numbers 25000008, 26107703, 14J03967. We also acknowledge support from the Tohoku University Division for International Advanced Research and Education Organization.

Effects of membrane deformability and bond formation/dissociation rates on adhesion dynamics of a spherical capsule in shear flow.

PubMed

Zhang, Ziying; Du, Jun; Wei, Zhengying; Wang, Zhen; Li, Minghui

2018-02-01

Cellular adhesion plays a critical role in biological systems and biomedical applications. Cell deformation and biophysical properties of adhesion molecules are of significance for the adhesion behavior. In the present work, dynamic adhesion of a deformable capsule to a planar substrate, in a linear shear flow, is numerically simulated to investigate the combined influence of membrane deformability (quantified by the capillary number) and bond formation/dissociation rates on the adhesion behavior. The computational model is based on the immersed boundary-lattice Boltzmann method for the capsule-fluid interaction and a probabilistic adhesion model for the capsule-substrate interaction. Three distinct adhesion states, detachment, rolling adhesion and firm adhesion, are identified and presented in a state diagram as a function of capillary number and bond dissociation rate. The impact of bond formation rate on the state diagram is further investigated. Results show that the critical bond dissociation rate for the transition of rolling or firm adhesion to detachment is strongly related to the capsule deformability. At the rolling-adhesion state, smaller off rates are needed for larger capillary number to increase the rolling velocity and detach the capsule. In contrast, the critical off rate for firm-to-detach transition slightly increases with the capillary number. With smaller on rate, the effect of capsule deformability on the critical off rates is more pronounced and capsules with moderate deformability are prone to detach by the shear flow. Further increasing of on rate leads to large expansion of both rolling-adhesion and firm-adhesion regions. Even capsules with relatively large deformability can maintain stable rolling adhesion at certain off rate.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marin, A.; Meneghini, C.; Mezzanotte, S.

The tongue was examined microscopically with various staining techniques 5, 15, and 30 days postirradiation. The mucous glands were consistently reduced in thickness, independent of the dose. As seen by the periodic acid-Schiff (PAS) reaction, the polysaccharide material took on a homogeneous appearance after irradiation in contrast to its granular form in control sections. The number of capillary vessels appeared to be increased 5 days after irradiation at all dose levels, whereas after 15 days the number was fewer than in control specimens. At 30 days, further changes were noted: with the 2000-r dose the number of vessels was normalmore » but with the 2 higher doses the number was below normal and many vessels were occluded. The occlusion resulted from hypertrophy of endothelial cells, and the basement membrane was thickened and stained more intensely than normal. The early apparent increase in the number of capillaries could not be traced to newly formed vessels but to dilatation of pre-existing ones. This increase in luminal diameter following irradiation was subsequently (at 15 to 30 days) obliterated by swelling of endothelium. Hemorrhagic changes were present at 5 days after all 3 doses but at 30 days were evident only after 5000 and 10 000 r. The findings are interpreted as indicating that interstitial polysaccharides are depolymerized by radiation and that the thickening of the capillary basement membrane represents increased permeability and accumulation of glycoproteins from the blood. (TCO)« less

Concept for Sustained Plant Production on ISS Using VEGGIE Capillary Mat Rooting System

NASA Technical Reports Server (NTRS)

Stutte, Gary W.; Newsham, Gerard; Morrow, Robert M.; Wheeler, Raymond M.

2011-01-01

Plant growth in microgravity presents unique challenges associated with maintaining appropriate conditions for seed germination, seedling establishment, maturation and harvest. They include maintaining appropriate soil moisture content, nutrient balance, atmospheric mixing and containment. Sustained production imposes additional challenges of harvesting, replanting, and safety. The VEGGIE is a deployable (collapsible) plant growth chamber developed as part of a NASA SBIR Phase II by Orbitec, Madison, WI. The intent of VEGGIE is to provide a low-resource system to produce fresh vegetables for the crew on long duration missions. The VEGGIE uses and LED array for lighting, an expandable bellows for containment, and a capillary matting system for nutrient and water delivery. The project evaluated a number of approaches to achieve sustained production, and repeated plantings, using the capillary rooting system. A number of different root media, seed containment, and nutrient delivery systems were evaluated and effects on seed germination and growth were evaluated. A number of issues limiting sustained production, such as accumulation of nutrients, uniform water, elevated vapor pressure deficit, and media containment were identified. A concept using pre-planted rooting packs shown to effectively address a number of those issues and is a promising approach for future development as a planting system for microgravity conditions.

Effect of gravity on liquid plug transport through an airway bifurcation model.

PubMed

Zheng, Y; Anderson, J C; Suresh, V; Grotberg, J B

2005-10-01

Many medical therapies require liquid plugs to be instilled into and delivered throughout the pulmonary airways. Improving these treatments requires a better understanding of how liquid distributes throughout these airways. In this study, gravitational and surface mechanisms determining the distribution of instilled liquids are examined experimentally using a bench-top model of a symmetrically bifurcating airway. A liquid plug was instilled into the parent tube and driven through the bifurcation by a syringe pump. The effect of gravity was adjusted by changing the roll angle (phi) and pitch angle (gamma) of the bifurcation (phi = gamma =0 deg was isogravitational). Phi determines the relative gravitational orientation of the two daughter tubes: when phi not equal to 0 deg, one daughter tube was lower (gravitationally favored) compared to the other. Gamma determines the component of gravity acting along the axial direction of the parent tube: when gamma not equal to 0 deg, a nonzero component of gravity acts along the axial direction of the parent tube. A splitting ratio Rs, is defined as the ratio of the liquid volume in the upper daughter to the lower just after plug splitting. We measured the splitting ratio, Rs, as a function of: the parent-tube capillary number (Cap); the Bond number (Bo); phi; gamma; and the presence of pre-existing plugs initially blocking either daughter tube. A critical capillary number (Cac) was found to exist below which no liquid entered the upper daughter (Rs = 0), and above which Rs increased and leveled off with Cap. Cac increased while Rs decreased with increasing phi, gamma, and Bo for blocked and unblocked cases at a given Cap > Ca,. Compared to the nonblockage cases, Rs decreased (increased) at a given Cap while Cac increased (decreased) with an upper (lower) liquid blockage. More liquid entered the unblocked daughter with a blockage in one daughter tube, and this effect was larger with larger gravity effect. A simple theoretical model that predicts Rs and Cac is in qualitative agreement with the experiments over a wide range of parameters.

Influence of Capillary Force and Buoyancy on CO2 Migration During CO2 Injection in a Sandstone Reservoir

NASA Astrophysics Data System (ADS)

Wu, H.; Pollyea, R.

2017-12-01

Carbon capture and sequestration (CCS) is one component of a broad carbon management portfolio designed to mitigate adverse effects of anthropogenic CO2 emissions. During CCS, capillary trapping is an important mechanism for CO2 isolation in the disposal reservoir, and, as a result, the distribution of capillary force is an important factor affecting CO2 migration. Moreover, the movement of CO2 being injected to the reservoir is also affected by buoyancy, which results from the density difference between CO2 and brine. In order to understand interactions between capillary force and buoyancy, we implement a parametric modeling experiment of CO2 injections in a sandstone reservoir for combinations of the van Genuchten capillary pressure model that bound the range of capillary pressure-saturation curves measured in laboratory experiments. We simulate ten years supercritical CO2 (scCO2) injections within a 2-D radially symmetric sandstone reservoir for five combinations of the van Genuchten model parameters λ and entry pressure (P0). Results are analyzed on the basis of a modified dimensionless ratio, ω, which is similar to the Bond number and defines the relationship between buoyancy pressure and capillary pressure. We show how parametric variability affects the relationship between buoyancy and capillary force, and thus controls CO2 plume geometry. These results indicate that when ω >1, then buoyancy governs the system and CO2 plume geometry is governed by upward flow. In contrast, when ω <1, then buoyancy is smaller than capillary force and lateral flow governs CO2 plume geometry. As a result, we show that the ω ratio is an easily implemented screening tool for qualitative assessment of reservoir performance.

Characteristics of a capillary-discharge flash x-ray generator

NASA Astrophysics Data System (ADS)

Sato, Eiichi; Hayasi, Yasuomi; Usuki, Tatsumi; Sato, Koetsu; Takayama, Kazuyoshi; Ido, Hideaki

2002-11-01

The fundamental experiments for measuring soft x-ray characteristics from the vacuum capillary are described. These experiments are primarily performed in order to generate line spectra such as x-ray lasers. The generator consists of a high-voltage power supply, a polarity-inversion ignitron pulse generator, a turbo-molecular pump, and a radiation tube with a capillary. A high-voltage condenser of 0.2 μF in the pulse generator is charged up to 20 kV by the power supply, and the electric charges in the condenser are discharged to the capillary in the tube after closing the ignitron. During the discharge, weakly ionized plasma forms on the inner and outer sides of a capillary. In the present work, the pump evacuates air from the tube with a pressure of about 1 mPa, and a demountable capillary was developed in order to measure x-ray spectra according to changes in the capillary length. In this capillary, the anode (target) and cathode elements can be changed corresponding to the objectives. The capillary diameter is 2.0 mm, and the length is adjusted from 1 to 50 mm. When a capillary with aluminum anode and cathode electrodes was employed, both the cathode voltage and the discharge current almost displayed damp oscillations. The peak values of the voltage and current increased when the charging voltage was increased and their maximum values were -10.8 kV and 4.7 kV, respectively. The x-ray durations observed by a 1.6 μm aluminum filter were less than 30 μs, and we detected the aluminum characteristic x-ray intensity using a 6.8 μm aluminum filter. In the spectrum measurement, two sets of aluminum and titanium electrodes were employed, and we observed multi-line spectra. The line photon energies seldom varied according to changes in teh condenser charging voltage and to changes in the electrode element. In the case where the titanium electrode was employed, the line number decreased with corresponding decreases in the capillary length. Compared with incoherent visible light, these rays from the capillary were diffracted greatly after pass through two slits.

Functionalized core-shell hydrogel microsprings by anisotropic gelation with bevel-tip capillary

PubMed Central

Yoshida, Koki; Onoe, Hiroaki

2017-01-01

This study describes a novel microfluidic-based method for the synthesis of hydrogel microsprings that are capable of encapsulating various functional materials. A continuous flow of alginate pre-gel solution can spontaneously form a hydrogel microspring by anisotropic gelation around the bevel-tip of the capillary. This technique allows fabrication of hydrogel microsprings using only simple capillaries and syringe pumps, while their complex compartmentalization characterized by a laminar flow inside the capillary can contribute to the optimization of the microspring internal structure and functionality. Encapsulation of several functional materials including magnetic-responsive nanoparticles or cell dispersed collagen for tissue scaffold was demonstrated to functionalize the microsprings. Our core-shell hydrogel microsprings have immense potential for application in a number of fields, including biological/chemical microsensors, biocompatible soft robots/microactuators, drug release, self-assembly of 3D structures and tissue engineering. PMID:28378803

Wettability control on fluid-fluid displacements in patterned microfluidics

NASA Astrophysics Data System (ADS)

Zhao, B.; MacMinn, C. W.; Juanes, R.

2015-12-01

Two-phase flow in porous media is important in many natural and industrial processes like geologic CO2 sequestration, enhanced oil recovery, and water infiltration in soil. While it is well known that the wetting properties of porous media can vary drastically depending on the type of media and the pore fluids, the effect of wettability on fluid displacement continues to challenge our microscopic and macroscopic descriptions. Here we conduct two-phase flow experiments via radial displacement of viscous silicone oil by water, in planar microfluidic devices patterned with vertical posts. These devices allow for visualization of flow through a complex but well-defined microstructure. In addition, the surface energy of the devices can be tuned over a wide range of contact angles, allowing us to access different wettability conditions. We use a fluorescent dye to measure the in-plane water saturation. We perform constant-rate injection experiments with highly unfavorable mobility contrast (viscosity of injected water is 350 times less than the displaced silicone oil) at injection rates over four orders of magnitude. We focus on three particular wetting conditions: drainage (θ=120°), weak imbibition (θ=60°), and strong imbibition (θ=7°). In drainage, we observe a transition from viscous fingering at high capillary numbers to a morphology that, in contrast with conventional knowledge, is different from capillary fingering. In weak imbibition, we observe an apparent stabilization of flow instabilities, as a result of cooperative invasion at the pore scale. In strong imbibition, we find that the flow behavior is heavily influenced by a precursor front that emanates from the main imbibition front. The nature of the precursor front depends on the capillary number. At intermediate capillary numbers, the precursor front consists primarily of corner flow that connects the surface of neighboring posts, forming ramified fingers. The progress of corner flow is overtaken by the spreading of precursor film (~1 um thick) at lower capillary numbers. The ensuing main imbibition front preferentially invades areas already coated by the precursor film, forming a more compact invasion pattern. Our work demonstrates the important, yet intricate, impact of wettability on the morphology of fluid-fluid displacement in porous media.

Effect of hindpaw electrical stimulation on capillary flow heterogeneity and oxygen delivery (Conference Presentation)

NASA Astrophysics Data System (ADS)

Li, Yuandong; Wei, Wei; Li, Chenxi; Wang, Ruikang K.

2017-02-01

We report a novel use of optical coherence tomography (OCT) based angiography to visualize and quantify dynamic response of cerebral capillary flow pattern in mice upon hindpaw electrical stimulation through the measurement of the capillary transit-time heterogeneity (CTH) and capillary mean transit time (MTT) in a wide dynamic range of a great number of vessels in vivo. The OCT system was developed to have a central wavelength of 1310 nm, a spatial resolution of 8 µm and a system dynamic range of 105 dB at an imaging rate of 92 kHz. The mapping of dynamic cerebral microcirculations was enabled by optical microangiography protocol. From the imaging results, the spatial homogenization of capillary velocity (decreased CTH) was observed in the region of interest (ROI) corresponding to the stimulation, along with an increase in the MTT in the ROI to maintain sufficient oxygen exchange within the brain tissue during functional activation. We validated the oxygen consumption due to an increase of the MTT through demonstrating an increase in the deoxygenated hemoglobin (HbR) during the stimulation by the use of laser speckle contrast imaging.

Behavior of CO2/water flow in porous media for CO2 geological storage.

PubMed

Jiang, Lanlan; Yu, Minghao; Liu, Yu; Yang, Mingjun; Zhang, Yi; Xue, Ziqiu; Suekane, Tetsuya; Song, Yongchen

2017-04-01

A clear understanding of two-phase fluid flow properties in porous media is of importance to CO 2 geological storage. The study visually measured the immiscible and miscible displacement of water by CO 2 using MRI (magnetic resonance imaging), and investigated the factor influencing the displacement process in porous media which were filled with quartz glass beads. For immiscible displacement at slow flow rates, the MR signal intensity of images increased because of CO 2 dissolution; before the dissolution phenomenon became inconspicuous at flow rate of 0.8mLmin -1 . For miscible displacement, the MR signal intensity decreased gradually independent of flow rates, because supercritical CO 2 and water became miscible in the beginning of CO 2 injection. CO 2 channeling or fingering phenomena were more obviously observed with lower permeable porous media. Capillary force decreases with increasing particle size, which would increase permeability and allow CO 2 and water to invade into small pore spaces more easily. The study also showed CO 2 flow patterns were dominated by dimensionless capillary number, changing from capillary finger to stable flow. The relative permeability curve was calculated using Brooks-Corey model, while the results showed the relative permeability of CO 2 slightly decreases with the increase of capillary number. Copyright © 2016 Elsevier Inc. All rights reserved.

Sensitive determination of four tetracycline antibiotics in pig plasma by field-amplified sample stacking open-tubular capillary electrochromatography with dimethylethanolamine aminated polychloromethyl styrene nano-latex coated capillary column.

PubMed

Guo, Yaxiao; Meng, Lei; Zhang, Yanhao; Tang, Wei; Zhang, Wenfen; Xia, Yan; Ban, Fuguo; Wu, Ningpeng; Zhang, Shusheng

2013-12-30

This paper described the preparation and application of a new dimethylethanolamine aminated polychloromethyl styrene nano-latex (DMEAPL) coated capillary column (ccc-DMEAPL) in the determination of four tetracycline antibiotics (TCA) including tetracycline (TC), oxytetracycline (OTC), doxycycline (DC) and chlorotetracycline (CTC) in pig plasma. The ccc-DMEAPL column was characterized with steady EOF values of ca. 1.5-5.2×10(-5)cm(2)/Vs at pH 1.8-6.3. The optimized conditions for field-amplified sample stacking open-tubular capillary electrochromatography (FASS-OT-CEC) were as following: background electrolyte, 10mmol/L Na2HPO4+15mmol/L citric acid (pH 3.2); ccc-DMEAPL, 50μm i.d.×50cm (effective length 41.5cm), separation voltage, 18kV; column temperature, 25°C; UV detection wavelength, 270nm; water-plug injection: 30mbar×10s; sample electrokinetic injection, 10kV×20s. The four TCA were extracted with the solution of 10mmol/L Na2HPO4+15mmol/L citric acid+4g/L EDTA-2Na (pH 3.2). The FASS-OT-CEC method was validated in terms of linearity, sensitivity, selectivity, precision and accuracy. The LODs ranged from 3 to 7ng/mL, the recoveries for the four TCA were all more than 80%. The developed method was successfully applied for the determination of TCs in the actual pig plasma samples. Copyright © 2013 Elsevier B.V. All rights reserved.

[Effect of electroacupuncture on the behavior and hippocampal ultrastructure in APP 695 V 717 I transgenic mice].

PubMed

Xue, Wei-Guo; Ge, Gui-Ling; Zhang, Zhong; Xu, Hong; Bai, Li-Min

2009-10-01

To investigate the ultrastructural basis underlying electroacupuncture (EA) induced improvement of Alzheimer disease (AD) in transgenic mice. Twelve APP 695 V 717 I transgenic mice were randomly divided into model group and EA group; and other 6 negative transgenic mice (C 57 BL/6 J) were made up of normal control group. After 3 months treatment by EA (15 min per other day, 2 Hz/100 Hz, 3-4 mA) applied to "Baihui" (GV 20) and "Yongquan" (KI 1), the learning and memory ability of mice was measured by Lashley III water maze test, and the ultrastructural changes of hippocampal CA 1 region was observed by electronic microscopy. The swimming escape latency and the number of navigating errors (dead-end forward swimming) in model group were significantly longer and more than those in normal control group (P < 0.05); and those in EA group were considerably shorter and fewer than those in model group (P < 0.05), suggesting an improvement of learning-memory ability after EA. Comparison of the ultrastructure of the neurons in the hippocampal CA 1 region showed swelling of the mitochondria, broken or disappearance of the mitochondrial cristae, degeneration of the synapses, breakage and vague outline of the basement membrane of the blood capillaries in mice of model group; and basically distinct outline of the mitochondrial cristae and microvessels, and more synaptic vesicles in EA group. EA may effectively improve the learning-memory capacity of the APP transgenic AD mice and alleviate the pathological changes of neurons of the hippocampal CA 1 region, which may be one of the mechanisms underlying the improvement of AD by EA.

On Porosity Formation in Metal Matrix Composites Made with Dual-Scale Fiber Reinforcements Using Pressure Infiltration Process

NASA Astrophysics Data System (ADS)

Etemadi, Reihaneh; Pillai, Krishna M.; Rohatgi, Pradeep K.; Hamidi, Sajad Ahmad

2015-05-01

This is the first such study on porosity formation phenomena observed in dual-scale fiber preforms during the synthesis of metal matrix composites (MMCs) using the gas pressure infiltration process. In this paper, different mechanisms of porosity formation during pressure infiltration of Al-Si alloys into Nextel™ 3D-woven ceramic fabric reinforcements (a dual-porosity or dual-scale porous medium) are studied. The effect of processing conditions on porosity content of the ceramic fabric infiltrated by the alloys through the gas PIP (PIP stands for "Pressure Infiltration Process" in which liquid metal is injected under pressure into a mold packed with reinforcing fibers.) is investigated. Relative density (RD), defined as the ratio of the actual MMC density and the density obtained at ideal 100 pct saturation of the preform, was used to quantify the overall porosity. Increasing the infiltration temperature led to an increase in RD due to reduced viscosity of liquid metal and enhanced wettability leading to improved feedability of the liquid metal. Similarly, increasing the infiltration pressure led to enhanced penetration of fiber tows and resulted in higher RD and reduced porosity. For the first time, the modified Capillary number ( Ca*), which is found to predict formation of porosity in polymer matrix composites quite well, is employed to study porosity in MMCs made using PIP. It is observed that in the high Ca* regime which is common in PIP, the overall porosity shows a strong downward trend with increasing Ca*. In addition, the effect of matrix shrinkage on porosity content of the samples is studied through using a zero-shrinkage Al-Si alloy as the matrix; usage of this alloy as the matrix led to a reduction in porosity content.

Radial fingering under arbitrary viscosity and density ratios

NASA Astrophysics Data System (ADS)

Anjos, Pedro H. A.; Dias, Eduardo O.; Miranda, José A.

2017-08-01

We study viscous fingering formation in radial Hele-Shaw cell geometry considering the combined action of capillary and inertial effects for arbitrary values of viscosity and density ratios. We tackle the problem by employing a perturbative mode-coupling approach and focus our attention on weakly nonlinear stages of the dynamics. If inertial effects are neglected, our theoretical results indicate that the shape of the resulting interfacial patterns is significantly affected by changes in the viscosity ratio. Under such conditions, the growing fingers tend to proliferate through a repeated ramification process (e.g., by finger bifurcation, quadrifurcation, etc.) as the capillary number is increased. Nevertheless, we find that this scenario is dramatically altered when inertia is taken into account. When inertia is relevant, the conventional finger splitting morphologies are replaced by three-lobed structures, characterized by the occurrence of sidebranching phenomena. We verify that slightly different types of sidebranched patterns arise, presenting either wide or sharp fingertips, for a range of capillary numbers and density ratios.

The Propagation of a Liquid Bolus Through an Elastic Tube and Airway Reopening

NASA Technical Reports Server (NTRS)

Howell, Peter D.; Grotberg, James B.

1996-01-01

We use lubrication theory and matched asymptotic expansions to model the quasi-steady propagation of a liquid bridge through an elastic tube. In the limit of small capillary number, asymptotic expressions are found for the pressure drop across the bridge and the thickness of the liquid film left behind, as functions of the capillary number, the thickness of the liquid lining ahead of the bridge and the elastic characteristics of the tube wall. For a given precursor thickness, we find a critical propagation speed, and hence a critical imposed pressure drop, above which the bridge will eventually burst, and hence the tube will reopen.

Minimal formulation of the linear spatial analysis of capillary jets: Validity of the two-mode approach

NASA Astrophysics Data System (ADS)

González, H.; Vazquez, P. A.; García, F. J.; Guerrero, J.

2018-04-01

A rigorous and complete formulation of the linear evolution of harmonically stimulated capillary jets should include infinitely many spatial modes to account for arbitrary exit conditions [J. Guerrero et al., J. Fluid Mech. 702, 354 (2012), 10.1017/jfm.2012.182]. However, it is not rare to find works in which only the downstream capillary dominant mode, the sole unstable one, is retained, with amplitude determined by the jet deformation at the exit. This procedure constitutes an oversimplification, unable to handle a flow rate perturbation without jet deformation at the exit (the most usual conditions). In spite of its decaying behavior, the other capillary mode (subdominant) must be included in what can be called a "minimal linear formulation." Deformation and mean axial velocity amplitudes at the jet exit are the two relevant parameters to simultaneously find the amplitudes of both capillary modes. Only once these amplitudes are found, the calculation of the breakup length may be eventually simplified by disregarding the subdominant mode. Simple recipes are provided for predicting the breakup length, which are checked against our own numerical simulations. The agreement is better than in previous attempts in the literature. Besides, the limits of validity of the linear formulation are explored in terms of the exit velocity amplitude, the wave number, the Weber number, and the Ohnesorge number. Including the subdominant mode extends the range of amplitudes for which the linear model gives accurate predictions, the criterion for keeping this mode being that the breakup time must be shorter than a given formula. It has been generally assumed that the shortest intact length happens for the stimulation frequency with the highest growth rate. However, we show that this correlation is not strict because the amplitude of the dominant mode has a role in the breakup process and it depends on the stimulation frequency.

The cellular lesion of humoral rejection: predominant recruitment of monocytes to peritubular and glomerular capillaries.

PubMed

Fahim, T; Böhmig, G A; Exner, M; Huttary, N; Kerschner, H; Kandutsch, S; Kerjaschki, D; Bramböck, A; Nagy-Bojarszky, K; Regele, H

2007-02-01

Accumulation of inflammatory cells within capillaries is a common morphologic feature of humoral renal allograft rejection and is most easily appreciated if it occurs in glomeruli. The aim of our study was to determine the amount and composition of immune cells within glomeruli and peritubular capillaries (PTC) in cellular and humoral allograft rejection. Immunofluorescent double-labeling for CD31 and CD3 or CD68 was used for phenotyping and enumerating immune cells within glomeruli and PTC. The major findings are: (1) accumulation of immune cells in PTC is far more common than it would be anticipated based on the assessment by conventional histology; (2) it is not the absolute number of immune cells accumulating within capillaries, but rather the composition of the intracapillary cell population that distinguishes humoral rejection from cellular rejection and (3) in C4d positive biopsies a predominantly monocytic cell population accumulates not only within glomeruli but also within PTC. The median value of monocyte/T-cell ratio within PTC was 2.3 in C4d positive biopsies but only 1 (p = 0.0008) in C4d negative biopsies. Given their prominent presence within capillaries and their extensive biological versatility monocytes might contribute to the capillary damage observed in acute and chronic allograft rejection.

Fine structure of the pecten oculi in the great horned owl (Bubo virginianus).

PubMed

Braekevelt, C R

1993-01-01

The pecten oculi of the great horned owl (Bubo virginianus) has been examined by light and electron microscopy. The pecten in this species is of the pleated type and is small in comparison to the size of the eyeball. It consists of 7-8 accordion folds which are joined apically by a pigmented bridge of tissue. Within each fold are numerous capillaries, larger supply and drainage vessels and plentiful pleomorphic melanocytes. The capillaries are extremely specialized vessels, most of which display plentiful microfolds on both their luminal and abluminal surfaces although some capillaries show but a few microfolds. The endothelial cell bodies are extremely thin with most organelles located near the nucleus. All capillaries are surrounded by a thick fibrillar basal lamina which is felt to be structurally important. Pericytes are a common feature within these thickened basal laminae. The numerous melanocytes form an incomplete sheath around the capillaries and are also presumed to be fulfilling a structural role. While the morphology of the pecten in the great horned owl is certainly indicative of a heavy involvement in transport, when compared to the pecten in species that are more visually oriented it is smaller, displays fewer folds and a reduced number of microfolds within the capillaries.

Cfd Simulation of Capillary Rise of Liquid in Cylindrical Container with Lateral Vanes

NASA Astrophysics Data System (ADS)

Liu, Xiaolin; Huang, Yiyong; Li, Guangyu

2016-06-01

Orbit refueling is one of the most significant technologies, which has vital strategic meaning. It can enhance the flexibility and prolong the lifetime of the spacecrafts. Space propellant management is one of the key technologies in orbit refueling. Based on the background of space propellant management, CFD simulations of capillary rise of liquid in Cylindrical container with lateral vanes in space condition were carried out in this paper. The influence of the size and the number of the vanes to the capillary flow were analyzed too. The results can be useful to the design and optimization of the propellant management device in the vane type surface tension tank.

Recent Developments in Instrumentation for Capillary Electrophoresis and Microchip-Capillary Electrophoresis

PubMed Central

Felhofer, Jessica L.; Blanes, Lucas; Garcia, Carlos D.

2010-01-01

Over the last years there has been an explosion in the number of developments and applications of capillary electrophoresis (CE) and microchip-CE. In part, this growth has been the direct consequence of recent developments in instrumentation associated with CE. This review, which is focused on contributions published in the last five years, is intended to complement the papers presented in this special issue dedicated to Instrumentation and to provide an overview on the general trend and some of the most remarkable developments published in the areas of high voltage power supplies, detectors, auxiliary components, and compact systems. It also includes few examples of alternative uses of and modifications to traditional CE instruments. PMID:20665910

Realizing A Mid-Infrared Optically Pumped Molecular Gas Laser Inside Hollow-Core Photonic Crystal Fiber

DTIC Science & Technology

2012-01-01

54  Figure 5.2 External transmission of (a) BK7 glass , (b) CaF2, and (c) Germanium substrates of various thicknesses. The transmission values...a hollow, air-filled core surrounded by cladding structure which is comprised of a periodic array of smaller air holes. Unlike glass capillaries...region of the fiber’s core. The low overlap of the guided light with the HC-PCF’s glass structure together with a higher threshold for the onset of

Intense laser pulse propagation in ionizing gases

NASA Astrophysics Data System (ADS)

Bian, Zhigang

2003-10-01

There have been considerable technological advances in the development of high intensity, short pulse lasers. However, high intensity laser pulses are subject to various laser-plasma instabilities. In this thesis, a theory is developed to study the scattering instability that occurs when a laser pulse propagates through and ionizes a gas. The instability is due to the intensity dependence of the ionization rate, which leads to a transversely structured free electron density. The instability is convective in the frame of laser pulse, but can have a relatively short growth length scaling as Lg˜k0/k2p where k0 is the laser wave number, k2p=w2p/c 2 and op is the plasma frequency. The most unstable perturbations correspond to a scattering angle for which the transverse wave number is around the plasma wave number, k p. The scattered light is frequency upshifted. The comparison between simple analytic theory and numerical simulation shows good agreement. Instabilities can drastically change the shape of the laser pulse and reduce the propagation distance of the laser pulse. Therefore, we change the propagation conditions and reduce the laser-plasma interaction possibilities in applications which require an interaction length well in excess of the Rayleigh length of the laser beam. One of the methods is to use a capillary to propagate the laser pulse. We studied the propagation of short pulses in a glass capillary. The propagation is simulated using the code WAKE, which has been modified to treat the case in which the simulation boundary is the wall of a capillary. Parameters that were examined include transmission efficiency of the waveguides as a function of gas pressure, laser intensity, and waveguide length, which is up to 40 Rayleigh lengths. The transmission efficiency decreases with waveguide length due to energy loss through the side-walls of the capillary. The loss increases with gas pressure due to ionization of the gas and scattering of the radiation. The intensity on the inner wall of the capillary is monitored to assure realistic simulations, consistent with optical breakdown of the waveguide material. Generally speaking the intensity on the wall increases with gas pressure due to the scattering of the lowest order capillary mode. Finally, the high order harmonic generation (HHG) in a capillary is investigated. The phase matching condition is studied to increase the conversion efficiency for high order harmonics generation. The phase matching occurs as a balance of the dispersion of the neutral gas, plasma and the waveguide.

Generation of capillary instabilities by external disturbances in a liquid jet. Ph.D. Thesis - State Univ. of N.Y.

NASA Technical Reports Server (NTRS)

Leib, S. J.

1985-01-01

The receptivity problem in a circular liquid jet is considered. A time harmonic axial pressure gradient is imposed on the steady, parallel flow of a jet of liquid emerging from a circular duct. Using a technique developed in plasma physics a casual solution to the forced problem is obtained over certain ranges of Weber number for a number of mean velocity profiles. This solution contains a term which grows exponentially in the downstream direction and can be identified with a capillary instability wave. Hence, it is found that the externally imposed disturbances can indeed trigger instability waves in a liquid jet. The amplitude of the instability wave generated relative to the amplitude of the forcing is computed numerically for a number of cases.

Capillary Driven Flows Along Differentially Wetted Interior Corners

NASA Technical Reports Server (NTRS)

Golliher, Eric L. (Technical Monitor); Nardin, C. L.; Weislogel, M. M.

2005-01-01

Closed-form analytic solutions useful for the design of capillary flows in a variety of containers possessing interior corners were recently collected and reviewed. Low-g drop tower and aircraft experiments performed at NASA to date show excellent agreement between theory and experiment for perfectly wetting fluids. The analytical expressions are general in terms of contact angle, but do not account for variations in contact angle between the various surfaces within the system. Such conditions may be desirable for capillary containment or to compute the behavior of capillary corner flows in containers consisting of different materials with widely varying wetting characteristics. A simple coordinate rotation is employed to recast the governing system of equations for flows in containers with interior corners with differing contact angles on the faces of the corner. The result is that a large number of capillary driven corner flows may be predicted with only slightly modified geometric functions dependent on corner angle and the two (or more) contact angles of the system. A numerical solution is employed to verify the new problem formulation. The benchmarked computations support the use of the existing theoretical approach to geometries with variable wettability. Simple experiments to confirm the theoretical findings are recommended. Favorable agreement between such experiments and the present theory may argue well for the extension of the analytic results to predict fluid performance in future large length scale capillary fluid systems for spacecraft as well as for small scale capillary systems on Earth.

Scanning Electron Microscopic Structure of the Lingual Papillae of the Common Opossum (Didelphis marsupialis)

NASA Astrophysics Data System (ADS)

Okada, Shigenori; Schraufnagel, Dean E.

2005-08-01

The mammalian tongue has evolved for specialized functions in different species. The structure of its papillae tells about the animal's diet, habit, and taxonomy. The opossum has four kinds of lingual papillae (filiform, conical, fungiform, vallate). Scanning electron microscopy of the external features, connective tissue cores, and corrosion casts of the microvasculature show the filiform papillae have a spearhead-like main process and spiny accessory processes around the apical part of the main process. The shape and number of both processes depend on their position on the tongue. On the apex, the main processes have shovel-like capillary networks and the accessory processes have small conical networks. On the lingual radix, the processes have small capillary loops. In the patch region, conical papillae have capillaries arranged as a full sail curving posteriorly. The fungiform papillae are scattered among the filiform papillae and have capillary baskets beneath each taste bud. Giant fungiform papillae on the tongue tip are three to four times larger than the ones on the lingual body. Capillaries of giant papillae form a fan-shaped network. The opossum has three vallate papillae arranged in a triangle. Their tops have secondary capillary loops but not their lateral surfaces. Mucosal folds on the posterolateral border have irregular, fingerlike projections with cylindrical capillary networks. These findings and the structure of the rest of the masticatory apparatus suggest the lingual papillae of opossum have kept their ancestral carnivorous features but also developed the herbivore characteristics of other marsupials.

Scanning electron microscopic structure of the lingual papillae of the common opossum (Didelphis marsupialis).

PubMed

Okada, Shigenori; Schraufnagel, Dean E

2005-08-01

The mammalian tongue has evolved for specialized functions in different species. The structure of its papillae tells about the animal's diet, habit, and taxonomy. The opossum has four kinds of lingual papillae (filiform, conical, fungiform, vallate). Scanning electron microscopy of the external features, connective tissue cores, and corrosion casts of the microvasculature show the filiform papillae have a spearhead-like main process and spiny accessory processes around the apical part of the main process. The shape and number of both processes depend on their position on the tongue. On the apex, the main processes have shovel-like capillary networks and the accessory processes have small conical networks. On the lingual radix, the processes have small capillary loops. In the patch region, conical papillae have capillaries arranged as a full sail curving posteriorly. The fungiform papillae are scattered among the filiform papillae and have capillary baskets beneath each taste bud. Giant fungiform papillae on the tongue tip are three to four times larger than the ones on the lingual body. Capillaries of giant papillae form a fan-shaped network. The opossum has three vallate papillae arranged in a triangle. Their tops have secondary capillary loops but not their lateral surfaces. Mucosal folds on the posterolateral border have irregular, fingerlike projections with cylindrical capillary networks. These findings and the structure of the rest of the masticatory apparatus suggest the lingual papillae of opossum have kept their ancestral carnivorous features but also developed the herbivore characteristics of other marsupials.

Fine structure of the pecten oculi of the barred owl (Strix varia).

PubMed

Smith, B J; Smith, S A; Braekevelt, C R

1996-01-01

The pecten oculi of the barred owl (Strix varia) has been examined by light and transmission electron microscopy. The pecten in this species is of the pleated type and is small in comparison to the size of the ocular globe. The pecten consists of 8-10 accordion-like folds that are linked apically by a pigmented tissue bridge. Each fold contains numerous capillaries, larger supply and drainage vessels, and abundant pleomorphic melanocytes. Most of these capillaries are extremely specialized vessels that possess plentiful microfolds on both the luminal and abluminal surfaces. Some capillaries however display only a few microfolds. The endothelial cell bodies are extremely attenuated, with most organelles located near the nucleus. All capillaries are surrounded by a very thick fibrillar basal lamina, which is thought to provide structural support to these small vessels. Pericytes are commonly found within these thickened basal laminae. Numerous melanocytes are also present, with processes that form an incomplete sheath around the capillaries. These processes are also presumed to provide structural support for the capillaries. As in other avian species, the morphology of the barred owl pecten is indicative of extensive involvement in substance transport. When compared to the pecten of more visually-oriented species, this pecten is smaller, has fewer folds, and displays a reduced number of microfolds within the capillaries. In these and other features, the barred owl pecten is similar to the pecten of the great horned owl (Bubo virginianus).

Inclusion evolution in molten and solidifying steel

NASA Astrophysics Data System (ADS)

Wang, Yan

Cleanliness, with respect to impurities and nonmetallic inclusions in the melt, is an important issue in steel production. The commercial interest in controlling steel cleanliness has been growing rapidly, because clean steel exhibits a highly attractive combination of corrosion resistance, good formability, pleasing appearance, and a wide range of strength levels. In order to satisfy the requirements for the degree of cleanliness in steel, controlling the size distribution, chemistry and shape of inclusions are of great importance in the steelmaking process. A knowledge of the formation of nonmetallic inclusions and their chemical and morphological evolution during the steelmaking and casting process is necessary in order to minimize the inclusion size and also try to promote potentially beneficial properties of inclusions, such as grain-refining. In this research, the evolution of inclusions in molten and solidifying steels was investigated through in-situ observations using a high temperature Confocal Scanning Laser Microscope (CSLM). The study focused on solid Al2O3 and liquid Al 2O3-CaO inclusions on low carbon steel melt surfaces. Firstly, the agglomeration and clustering of inclusions on steel surfaces were quantified and compared to predictions according to capillary depression driven attraction forces. A strong agglomeration was observed between the solid Al2O33 particle pairs. However, the liquid Al 2O3-CaO inclusions were not prone to agglomeration due to their lens-like morphology, which causes the absence of capillary force. Secondly, the pushing vs. engulfment and entrapment of both liquid Al 2O3-CaO and solid Al2O3 inclusions by advancing planar and cellular delta-ferrite solidification fronts was studied and compared to model predictions based on the force balances acting on the inclusions at the solid/melt interface. The critical velocity, above which the inclusions get engulfed, was observed to be slower at the cellular front than at the planar interface for liquid Al2O3-CaO inclusions. This indicates that these inclusions tend to more easily get engulfed at inter-cellular boundaries. However, there was no appreciable difference observed about the critical velocity for the large solid Al2O 3 inclusion clusters at the cellular boundary with that at the planar interface. The pushed liquid Al2O3-CaO inclusions were subject to a chemical and morphological change during solidification. (Abstract shortened by UMI.)

High Reynolds Number Thermal Stability Experiments

NASA Technical Reports Server (NTRS)

Emens, Jessica M.; Brown, Sarah P.; Frederick Robert A., Jr.; Wood, A. John

2004-01-01

This work represents preliminary thermal stability results for liquid hydrocarbon fuels. High Reynolds Number Thermal Stability experiments with Jet A and RP-1 resulted in a quantitative measurement of the thermal stability. Each fuel flowed through a heated capillary tube that held the outlet temperature at 290 C. An optical pyrometer measured the surface temperature of the tube at 12 locations as a function of time. The High Reynolds Number Thermal Stability number was then determined using standards published by the American Society for Testing and Materials. The results for Jet A showed lower thermal stability than similar tests conducted at another facility. The RP-1 results are the first reported using this technique. Because the temperature rise on the capillary tube during testing for the RP-1 fuels was not significant, a new standard for the testing conditions should be developed for these types of fuels.

Three-Dimensional Simulation of Liquid Drop Dynamics Within Unsaturated Vertical Hele-Shaw Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hai Huang; Paul Meakin

A three-dimensional, multiphase fluid flow model with volume of fluid-interface tracking was developed and applied to study the multiphase dynamics of moving liquid drops of different sizes within vertical Hele-Shaw cells. The simulated moving velocities are significantly different from those obtained from a first-order analytical approximation, based on simple force-balance concepts. The simulation results also indicate that the moving drops can exhibit a variety of shapes and that the transition among these different shapes is largely determined by the moving velocities. More important, there is a transition from a linear moving regime at small capillary numbers, in which the capillarymore » number scales linearly with the Bond number, to a nonlinear moving regime at large capillary numbers, in which the moving drop releases a train of droplets from its trailing edge. The train of droplets forms a variety of patterns at different moving velocities.« less

High-throughput biological small-angle X-ray scattering with a robotically loaded capillary cell

PubMed Central

Nielsen, S. S.; Møller, M.; Gillilan, R. E.

2012-01-01

With the rise in popularity of biological small-angle X-ray scattering (BioSAXS) measurements, synchrotron beamlines are confronted with an ever-increasing number of samples from a wide range of solution conditions. To meet these demands, an increasing number of beamlines worldwide have begun to provide automated liquid-handling systems for sample loading. This article presents an automated sample-loading system for BioSAXS beamlines, which combines single-channel disposable-tip pipetting with a vacuum-enclosed temperature-controlled capillary flow cell. The design incorporates an easily changeable capillary to reduce the incidence of X-ray window fouling and cross contamination. Both the robot-control and the data-processing systems are written in Python. The data-processing code, RAW, has been enhanced with several new features to form a user-friendly BioSAXS pipeline for the robot. The flow cell also supports efficient manual loading and sample recovery. An effective rinse protocol for the sample cell is developed and tested. Fluid dynamics within the sample capillary reveals a vortex ring pattern of circulation that redistributes radiation-damaged material. Radiation damage is most severe in the boundary layer near the capillary surface. At typical flow speeds, capillaries below 2 mm in diameter are beginning to enter the Stokes (creeping flow) regime in which mixing due to oscillation is limited. Analysis within this regime shows that single-pass exposure and multiple-pass exposure of a sample plug are functionally the same with regard to exposed volume when plug motion reversal is slow. The robot was tested on three different beamlines at the Cornell High-Energy Synchrotron Source, with a variety of detectors and beam characteristics, and it has been used successfully in several published studies as well as in two introductory short courses on basic BioSAXS methods. PMID:22509071

Endurance training in the spontaneously hypertensive rat: conversion of pathological into physiological cardiac hypertrophy.

PubMed

Garciarena, Carolina D; Pinilla, Oscar A; Nolly, Mariela B; Laguens, Ruben P; Escudero, Eduardo M; Cingolani, Horacio E; Ennis, Irene L

2009-04-01

The effect of endurance training (swimming 90 min/d for 5 days a week for 60 days) on cardiac hypertrophy was investigated in the spontaneously hypertensive rat (SHR). Sedentary SHRs (SHR-Cs) and normotensive Wistar rats were used as controls. Exercise training enhanced myocardial hypertrophy assessed by left ventricular weight/tibial length (228+/-7 versus 251+/-5 mg/cm in SHR-Cs and exercised SHRs [SHR-Es], respectively). Myocyte cross-sectional area increased approximately 40%, collagen volume fraction decreased approximately 50%, and capillary density increased approximately 45% in SHR-Es compared with SHR-Cs. The mRNA abundance of atrial natriuretic factor and myosin light chain 2 was decreased by the swimming routine (100+/-19% versus 41+/-10% and 100+/-8% versus 61+/-9% for atrial natriuretic factor and myosin light chain 2 in SHR-Cs and SHR-Es, respectively). The expression of sarcoplasmic reticulum Ca(2+) pump was significantly augmented, whereas that of Na(+)/Ca(2+) exchanger was unchanged (93+/-7% versus 167+/-8% and 158+/-13% versus 157+/-7%, sarcoplasmic reticulum Ca(2+) pump and Na(+)/Ca(2+) exchanger in SHR-Cs and SHR-Es, respectively; P<0.05). Endurance training inhibited apoptosis, as reflected by a decrease in caspase 3 activation and poly(ADP-ribose) polymerase-1 cleavage, and normalized calcineurin activity without inducing significant changes in the phosphatidylinositol 3-kinase/Akt pathway. The swimming routine improved midventricular shortening determined by echocardiography (32.4+/-0.9% versus 36.9+/-1.1% in SHR-Cs and SHR-Es, respectively; P<0.05) and decreased the left ventricular free wall thickness/left ventricular cavity radius toward an eccentric model of cardiac hypertrophy (0.59+/-0.02 versus 0.53+/-0.01 in SHR-Cs and SHR-Es, respectively; P<0.05). In conclusion, we present data demonstrating the effectiveness of endurance training to convert pathological into physiological hypertrophy improving cardiac performance. The reduction of myocardial fibrosis and calcineurin activity plus the increase in capillary density represent factors to be considered in determining this beneficial effect.

Hypoxic stress up-regulates Kir2.1 expression and facilitates cell proliferation in brain capillary endothelial cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamamura, Hideto; Suzuki, Yoshiaki; Yamamura, Hisao

The blood-brain barrier (BBB) is mainly composed of brain capillary endothelial cells (BCECs), astrocytes and pericytes. Brain ischemia causes hypoxic encephalopathy and damages BBB. However, it remains still unclear how hypoxia affects BCECs. In the present study, t-BBEC117 cells, an immortalized bovine brain endothelial cell line, were cultured under hypoxic conditions at 4–5% oxygen for 72 h. This hypoxic stress caused hyperpolarization of resting membrane potential. Patch-clamp recordings revealed a marked increase in Ba{sup 2+}-sensitive inward rectifier K{sup +} current in t-BBEC117 cells after hypoxic culture. Western blot and real-time PCR analyses showed that Kir2.1 expression was significantly up-regulated at protein level butmore » not at mRNA level after the hypoxic culture. Ca{sup 2+} imaging study revealed that the hypoxic stress enhanced store-operated Ca{sup 2+} (SOC) entry, which was significantly reduced in the presence of 100 μM Ba{sup 2+}. On the other hand, the expression of SOC channels such as Orai1, Orai2, and transient receptor potential channels was not affected by hypoxic stress. MTT assay showed that the hypoxic stress significantly enhanced t-BBEC117 cell proliferation, which was inhibited by approximately 60% in the presence of 100 μM Ba{sup 2+}. We first show here that moderate cellular stress by cultivation under hypoxic conditions hyperpolarizes membrane potential via the up-regulation of functional Kir2.1 expression and presumably enhances Ca{sup 2+} entry, resulting in the facilitation of BCEC proliferation. These findings suggest potential roles of Kir2.1 expression in functional changes of BCECs in BBB following ischemia. -- Highlights: •Hypoxic culture of brain endothelial cells (BEC) caused membrane hyperpolarization. •This hyperpolarization was due to the increased expression of Kir2.1 channels. •Hypoxia enhanced store-operated Ca{sup 2+} (SOC) entry via Kir2.1 up-regulation. •Expression levels of putative SOC channels were not affected by hypoxia. •Kir2.1 up-regulation is responsible for hypoxia-enhanced BEC proliferation.« less

The interface of an array of five capillaries with an array of one-nanoliter wells for high-resolution electrophoretic analysis as an approach to high-throughput chemical cytometry

PubMed Central

Boardman, Anna; McQuaide, Sarah C.; Zhu, Cuiru; Whitmore, Colin; Lidstrom, Mary E.; Dovichi, Norman J.

2009-01-01

We report a system that allows the simultaneous aspiration of one or more cells into each of five capillaries for electrophoresis analysis. A glass wafer was etched to create an array of 1 nL wells. The glass was treated with poly(2-hydroxyethyl methacrylate) to control cell adherence. A suspension of formalin-fixed cells was placed on the surface, and cells were allowed to settle. The concentration of cells and the settling time were chosen so that there was, on average, one cell per well. Next, an array of five capillaries was placed so that the tip of each capillary was in contact with a single well. A pulse of vacuum was applied to the distal end of the capillaries to aspirate the content of each well into a capillary. Next, the tips of the capillaries were placed in running buffer and potential was applied. The cells lysed upon contact with the running buffer, and fluorescent components were detected at the distal end of the capillaries by laser-induced fluorescence. The electrophoretic separation efficiency was outstanding, generating over 750,000 theoretical plates (1,800,000 plates/meter). In this example, AtT-20 cells were used that had been treated with TMR-GM1. The cells were allowed to metabolize this substrate into a series of products before the cells were fixed. The number of cells found in each well was estimated visually under the microscope and was described by a Poisson distribution with mean of 0.95 cells/well. This system provides an approach to high-throughput chemical cytometry. PMID:18717573

Impact of maternal diabetes type 1 on proliferative potential, differentiation and apoptotic activity in villous capillaries of term placenta.

PubMed

Jirkovská, Marie; Kučera, Tomáš; Dvořáková, Veronika; Jadrníček, Martin; Moravcová, Milena; Žižka, Zdeněk; Krejčí, Vratislav

2016-04-01

Maternal diabetes mellitus changes morphology and impairs function of placental capillaries. Here, quantitative parameters characterizing cell proliferation using detection of Ki67, differentiation reflected by nestin expression and apoptosis in placental capillary bed with active caspase 3 as a marker were compared in normal term placentas and placentas from pregnancies complicated by Type 1 maternal diabetes mellitus. Specimens of sixteen diabetic placentas and eight control placentas were collected by systematic uniform random sampling. Immunohistochemical detections of Ki67, nestin, and active caspase 3 were performed in histological sections of five haphazardly chosen blocks per placenta. Twenty fields of view per section, i.e. one hundred fields of view per placenta, were used for analysis of proliferation as well as of apoptosis, and in approximately 70 capillary cross-sections per placenta the nestin-positive segments of their circumference were measured. The percentage of Ki67-positive cells counted in the capillary wall was significantly lower in diabetic group. The counts of Ki67-labelled nuclei per villous area unit were significantly lower in cytotrophoblast and capillary wall of terminal villi in diabetic placenta. The proportion of nestin-labeled segments of capillary circumference was significantly higher in placentas of diabetic group. No differences in the numbers of apoptotic cells were found between studied groups. The results show that the term placenta in Type 1 diabetes has lower potential to enlarge the surface area of structures involved in maternofetal transport, and that the villous capillary bed displays delayed differentiation. Those factors may participate in decreased ability of diabetic placenta to comply with fetal requirements in the final stage of pregnancy. Copyright © 2016 Elsevier Ltd. All rights reserved.

Lower capillary density but no difference in VEGF expression in obese vs. lean young skeletal muscle in humans.

PubMed

Gavin, Timothy P; Stallings, Howard W; Zwetsloot, Kevin A; Westerkamp, Lenna M; Ryan, Nicholas A; Moore, Rebecca A; Pofahl, Walter E; Hickner, Robert C

2005-01-01

Obesity is associated with lower skeletal muscle capillarization and lower insulin sensitivity. Vascular endothelial growth factor (VEGF) is important for the maintenance of the skeletal muscle capillaries. To investigate whether VEGF and VEGF receptor [kinase insert domain-containing receptor (KDR) and Flt-1] expression are lower with obesity, vastus lateralis muscle biopsies were obtained from eight obese and eight lean young sedentary men before and 2 h after a 1-h submaximal aerobic exercise bout for the measurement of VEGF, KDR, Flt-1, and skeletal muscle fiber and capillary characteristics. There were no differences in VEGF or VEGF receptor mRNA at rest between lean and obese muscle. Exercise increased VEGF (10-fold), KDR (3-fold), and Flt-1 (5-fold) mRNA independent of group. There were no differences in VEGF, KDR, or Flt-1 protein between groups. Compared with lean skeletal muscle, the number of capillary contacts per fiber was the same, but lower capillary density (CD), greater muscle cross sectional area, and lower capillary-to-fiber area ratio were observed in both type I and II fibers in obese muscle. Multiple linear regression revealed that 49% of the variance in insulin sensitivity (homeostasis model assessment) could be explained by percentage of body fat (35%) and maximal oxygen uptake per kilogram of fat-free mass (14%). Linear regression revealed significant relationships between maximal oxygen uptake and both CD and capillary-to-fiber perimeter exchange. Although differences may exist in CD and capillary-to-fiber area ratio between lean and obese skeletal muscle, the present results provide evidence that VEGF and VEGF receptor expression are not different between lean and obese muscle.

Experimental techniques and computational methods toward the estimation of the effective two-phase flow coefficients and multi-scale heterogeneities of soils

NASA Astrophysics Data System (ADS)

Tsakiroglou, C. D.; Aggelopoulos, C. A.; Sygouni, V.

2009-04-01

A hierarchical, network-type, dynamic simulator of the immiscible displacement of water by oil in heterogeneous porous media is developed to simulate the rate-controlled displacement of two fluids at the soil column scale. A cubic network is constructed, where each node is assigned a permeability which is chosen randomly from a distribution function. The intensity of heterogeneities is quantified by the width of the permeability distribution function. The capillary pressure at each node is calculated by combining a generalized Leverett J-function with a Corey type model. Information about the heterogeneity of soils at the pore network scale is obtained by combining mercury intrusion porosimetry (MIP) data with back-scattered scanning electron microscope (BSEM) images [1]. In order to estimate the two-phase flow properties of nodes (relative permeability and capillary pressure functions, permeability distribution function) immiscible and miscible displacement experiments are performed on undisturbed soil columns. The transient responses of measured variables (pressure drop, fluid saturation averaged over five successive segments, solute concentration averaged over three cross-sections) are fitted with models accounting for the preferential flow paths at the micro- (multi-region model) and macro-scale (multi flowpath model) because of multi-scale heterogeneities [2,3]. Simulating the immiscible displacement of water by oil (drainage) in a large netork, at each time step, the fluid saturation and pressure of each node are calculated formulating mass balances at each node, accounting for capillary, viscous and gravity forces, and solving the system of coupled equations. At each iteration of the algorithm, the pressure drop is so selected that the total flow rate of the injected fluid is kept constant. The dynamic large-scale network simulator is used (1) to examine the sensitivity of the transient responses of the axial distribution of fluid saturation and total pressure drop across the network to the permeability distribution function, spatial correlations of permeability, and capillary number, and (2) to estimate the effective (up-scaled) relative permeability functions at the soil column scale. In an attempt to clarify potential effects of the permeability distribution and spatial permeability correlations on the transient responses of the pressure drop across a soil column, signal analysis with wavelets is performed [4] on experimental and simulated results. The transient variation of signal energy and frequency of pressure drop fluctuations at the wavelet domain are correlated with macroscopic properties such as the effective water and oil relative permeabilities of the porous medium, and microscopic properties such as the variation of the permeability distribution of oil-occupied nodes. Toward the solution of the inverse problem, a general procedure is suggested to identify macro-heterogeneities from the fast analysis of pressure drop signals. References 1. Tsakiroglou, C.D. and M.A. Ioannidis, "Dual porosity modeling of the pore structure and transport properties of a contaminated soil", Eur. J. Soil Sci., 59, 744-761 (2008). 2. Aggelopoulos, C.A., and C.D. Tsakiroglou, "Quantifying the Soil Heterogeneity from Solute Dispersion Experiments", Geoderma, 146, 412-424 (2008). 3. Aggelopoulos, C.A., and C.D. Tsakiroglou, "A multi-flow path approach to model immiscible displacement in undisturbed heterogeneous soil columns", J. Contam. Hydrol., in press (2009). 4. Sygouni, V., C.D. Tsakiroglou, and A.C. Payatakes, "Using wavelets to characterize the wettability of porous materials", Phys. Rev. E, 76, 056304 (2007).

Hardening of particle/oil/water suspensions due to capillary bridges: Experimental yield stress and theoretical interpretation.

PubMed

Danov, Krassimir D; Georgiev, Mihail T; Kralchevsky, Peter A; Radulova, Gergana M; Gurkov, Theodor D; Stoyanov, Simeon D; Pelan, Eddie G

2018-01-01

Suspensions of colloid particles possess the remarkable property to solidify upon the addition of minimal amount of a second liquid that preferentially wets the particles. The hardening is due to the formation of capillary bridges (pendular rings), which connect the particles. Here, we review works on the mechanical properties of such suspensions and related works on the capillary-bridge force, and present new rheological data for the weakly studied concentration range 30-55 vol% particles. The mechanical strength of the solidified capillary suspensions, characterized by the yield stress Y, is measured at the elastic limit for various volume fractions of the particles and the preferentially wetting liquid. A quantitative theoretical model is developed, which relates Y with the maximum of the capillary-bridge force, projected on the shear plane. A semi-empirical expression for the mean number of capillary bridges per particle is proposed. The model agrees very well with the experimental data and gives a quantitative description of the yield stress, which increases with the rise of interfacial tension and with the volume fractions of particles and capillary bridges, but decreases with the rise of particle radius and contact angle. The quantitative description of capillary force is based on the exact theory and numerical calculation of the capillary bridge profile at various bridge volumes and contact angles. An analytical formula for Y is also derived. The comparison of the theoretical and experimental strain at the elastic limit reveals that the fluidization of the capillary suspension takes place only in a deformation zone of thickness up to several hundred particle diameters, which is adjacent to the rheometer's mobile plate. The reported experimental results refer to water-continuous suspension with hydrophobic particles and oily capillary bridges. The comparison of data for bridges from soybean oil and hexadecane surprisingly indicate that the yield strength is greater for the suspension with soybean oil despite its lower interfacial tension against water. The result can be explained with the different contact angles of the two oils in agreement with the theoretical predictions. The results could contribute for a better understanding, quantitative prediction and control of the mechanical properties of three-phase capillary suspensions solid/liquid/liquid. Copyright © 2017 Elsevier B.V. All rights reserved.

Biomonitoring of airborne particulate matter emitted from a cement plant and comparison with dispersion modelling results

NASA Astrophysics Data System (ADS)

Abril, Gabriela A.; Wannaz, Eduardo D.; Mateos, Ana C.; Pignata, María L.

2014-01-01

The influence of a cement plant that incinerates industrial waste on the air quality of a region in the province of Córdoba, Argentina, was assessed by means of biomonitoring studies (effects of immission) and atmospheric dispersion (effects of emission) of PM10 with the application of the ISC3 model (Industrial Source Complex) developed by the USEPA (Environmental Protection Agency). For the biomonitoring studies, samples from the epiphyte plant Tillandsia capillaris Ruíz & Pav. f. capillaris were transplanted to the vicinities of the cement plant in order to determine the physiological damage and heavy metal accumulation (Ca, Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb). For the application of the ISC3 model, point and area sources from the cement plant were considered to obtain average PM10 concentration results from the biomonitoring exposure period. This model permitted it to be determined that the emissions from the cement plant (point and area sources) were confined to the vicinities, without significant dispersion in the study area. This was also observed in the biomonitoring study, which identified Ca, Cd and Pb, pH and electric conductivity (EC) as biomarkers of this cement plant. Vehicular traffic emissions and soil re-suspension could be observed in the biomonitors, giving a more complete scenario. In this study, biomonitoring studies along with the application of atmospheric dispersion models, allowed the atmospheric pollution to be assessed in more detail.

Charge-based characterization of nanometric cationic bifunctional maghemite/silica core/shell particles by capillary zone electrophoresis.

PubMed

d'Orlyé, Fanny; Varenne, Anne; Georgelin, Thomas; Siaugue, Jean-Michel; Teste, Bruno; Descroix, Stéphanie; Gareil, Pierre

2009-07-01

In view of employing functionalized nanoparticles (NPs) in the context of an immunodiagnostic, aminated maghemite/silica core/shell particles were synthesized so as to be further coated with an antibody or an antigen via the amino groups at their surface. Different functionalization rates were obtained by coating these maghemite/silica core/shell particles with 3-(aminopropyl)triethoxysilane and 2-[methoxy(polyethyleneoxy)propyl]-trimethoxysilane at different molar ratios. Adequate analytical performances with CE coupled with UV-visible detection were obtained through semi-permanent capillary coating with didodecyldimethyl-ammonium bromide, thus preventing particle adsorption. First, the influence of experimental conditions such as electric field strength, injected particle amount as well as electrolyte ionic strength and pH, was evaluated. A charge-dependent electrophoretic mobility was evidenced and the separation selectivity was tuned according to electrolyte ionic strength and pH. The best resolutions were obtained at pH 8.0, high ionic strength (ca. 100 mM), and low total particle volume fraction (ca. 0.055%), thus eliminating interference effects between different particle populations in mixtures. A protocol derived from Kaiser's original description was performed for quantitation of the primary amino groups attached onto the NP surface. Thereafter a correlation between particle electrophoretic mobility and the density of amino groups at their surface was established. Eventually, CE proved to be an easy, fast, and reliable method for the determination of NP effective surface charge density.

Comparison of histamine and hyperosmotic arabinose infusion on brain capillary permeability to hydrophilic solutes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lucchesi, K.J.

1986-03-01

The effect of bilateral intracarotid infusion of histamine (HA) on capillary permeability-surface area products (PS) of two metabolically inert tracers was determined and compared to that of L(+)arabinose (ARAB) in rat brain. Ringer's solution alone, or with 1 mg/kg HA diphosphate or 1.6M ARAB added, was infused (0.9 ml over 0.5 min) into each external carotid artery (CA). Five minutes later, a bolus of /sup 14/C-sucrose and /sup 3/H-L-glucose was injected i.v. Estimates of PS for both tracers were computed by the method of Ohno et al after brain concentration was corrected for tracer within cerebral blood vessels. Brain bloodmore » volume, based on the /sup 14/C-dextran space, was the same (.016 ml/g) in discrete cortical and midbrain regions of all rats except those treated with ARAB. The latter yielded .033 ml/g, presumably due to dextran extravasation. Infusion of ARAB, HA and Ringer's increased the PS's of sucrose and L-glucose by 10x, 8x, and 3x in brain regions perfused by the internal CA's. The ratio, PS-sucrose/PS-L-glucose was unchanged by any treatment. Both ARAB and HA caused transient falls in arterial pressure, but only ARAB caused deaths (3 of 9 rats). While as effective as ARAB in opening the blood-brain barrier, HA may be safer than hyperosmotic shock to enhance delivery of chemotherapeutic agents to brain tumors.« less

Near-infrared laser-induced fluorescence detection in capillary electrophoresis.

PubMed

McWhorter, S; Soper, S A

2000-04-01

As capillary electrophoresis continues to focus on miniaturization, either through reducing column dimensions or situating entire electrophoresis systems on planar chips, advances in detection become necessary to meet the challenges posed by these electrophoresis platforms. The challenges result from the fact that miniaturization requires smaller load volumes, demanding highly sensitive detection. In addition, many times multiple targets must be analyzed simultaneously (multiplexed applications), further complicating detection. Near-infrared (NIR) fluorescence offers an attractive alternative to visible fluorescence for critical applications in capillary electrophoresis due to the impressive limits of detection that can be generated, in part resulting from the low background levels that are observed in the NIR. Advances in instrumentation and fluorogenic labels appropriate for NIR monitoring have led to a growing number of examples of the use of NIR fluorescence in capillary electrophoresis. In this review, we will cover instrumental components used to construct ultrasensitive NIR fluorescence detectors, including light sources and photon transducers. In addition, we will discuss various types of labeling dyes appropriate for NIR fluorescence and finally, we will present several applications that have used NIR fluorescence in capillary electrophoresis, especially for DNA sequencing and fragment analysis.

Polycythemia, capillary rarefaction, and focal glomerulosclerosis in two adolescents born extremely low birth weight and premature.

PubMed

Asada, Nariaki; Tsukahara, Takanori; Furuhata, Megumi; Matsuoka, Daisuke; Noda, Shunsuke; Naganuma, Kuniaki; Hashiguchi, Akinori; Awazu, Midori

2017-07-01

Low birthweight infants have a reduced number of nephrons and are at high risk of chronic kidney disease. Preterm birth and/or intrauterine growth restriction (IUGR) may also affect peritubular capillary development, as has been shown in other organs. We report two patients with a history of preterm birth and extremely low birthweight who showed polycythemia and renal capillary rarefaction. Patient 1 and 2, born at 25 weeks of gestation with a birthweight of 728 and 466 g, showed mild proteinuria at age 8 and 6 years, respectively. In addition to increasing proteinuria, hemoglobin levels became elevated towards adolescence and their serum erythropoietin (EPO) was high despite polycythemia. Light microscopic examination of renal biopsy specimens showed glomerular hypertrophy, focal segmental glomerulosclerosis, and only mild tubulointerstitial fibrosis. A decrease in the immunohistochemical staining of CD31 and CD34 endothelial cells in renal biopsy specimens was consistent with peritubular capillary rarefaction. Since kidney function was almost normal and fibrosis was not severe, we consider that the capillary rarefaction and polycythemia associated with elevated EPO levels were largely attributable to preterm birth and/or IUGR.

Twisting microfluidics in a planetary centrifuge.

PubMed

Yasuda, Shoya; Hayakawa, Masayuki; Onoe, Hiroaki; Takinoue, Masahiro

2017-03-15

This paper reports a twisting microfluidic method utilising a centrifuge-based fluid extruding system in a planetary centrifuge which simultaneously generates an orbital rotation and an axial spin. In this method, fluid extrusion from a micro-scale capillary to an 'open-space' solution or air enables release of the fluid from the capillary-based microchannel, which physically means that there is a release of fluids from a confined low-Reynolds-number environment to an open non-low-Reynolds-number environment. As a result, the extruded fluids are separated from the axial spin of the capillary, and the difference in the angular rates of the axial spin between the capillary and the extruded fluids produces the 'twisting' of the fluid. In this study, we achieve control of the twist of highly viscous fluids, and we construct a simple physical model for the fluid twist. In addition, we demonstrate the formation of twisted hydrogel microstructures (stripe-patterned microbeads and multi-helical microfibres) with control over the stripe pattern and the helical pitch length. We believe that this method will enable the generation of more sophisticated microstructures which cannot easily be formed by usual channel-based microfluidic devices. This method can also provide advanced control of microfluids, as in the case of rapid mixing of highly viscous fluids. This method can contribute to a wide range of applications in materials science, biophysics, biomedical science, and microengineering in the future.

Capillary fluctuations of surface steps: An atomistic simulation study for the model Cu(111) system

NASA Astrophysics Data System (ADS)

Freitas, Rodrigo; Frolov, Timofey; Asta, Mark

2017-10-01

Molecular dynamics (MD) simulations are employed to investigate the capillary fluctuations of steps on the surface of a model metal system. The fluctuation spectrum, characterized by the wave number (k ) dependence of the mean squared capillary-wave amplitudes and associated relaxation times, is calculated for 〈110 〉 and 〈112 〉 steps on the {111 } surface of elemental copper near the melting temperature of the classical potential model considered. Step stiffnesses are derived from the MD results, yielding values from the largest system sizes of (37 ±1 ) meV/A ˚ for the different line orientations, implying that the stiffness is isotropic within the statistical precision of the calculations. The fluctuation lifetimes are found to vary by approximately four orders of magnitude over the range of wave numbers investigated, displaying a k dependence consistent with kinetics governed by step-edge mediated diffusion. The values for step stiffness derived from these simulations are compared to step free energies for the same system and temperature obtained in a recent MD-based thermodynamic-integration (TI) study [Freitas, Frolov, and Asta, Phys. Rev. B 95, 155444 (2017), 10.1103/PhysRevB.95.155444]. Results from the capillary-fluctuation analysis and TI calculations yield statistically significant differences that are discussed within the framework of statistical-mechanical theories for configurational contributions to step free energies.

Predictors of cardiovascular fitness in sedentary men.

PubMed

Riou, Marie-Eve; Pigeon, Etienne; St-Onge, Josée; Tremblay, Angelo; Marette, André; Weisnagel, S John; Joanisse, Denis R

2009-04-01

The relative contribution of anthropometric and skeletal muscle characteristics to cardiorespiratory fitness was studied in sedentary men. Cardiorespiratory fitness (maximal oxygen consumption) was assessed using an incremental bicycle ergometer protocol in 37 men aged 34-53 years. Vastus lateralis muscle biopsy samples were used to assess fiber type composition (I, IIA, IIX) and areas, capillary density, and activities of glycolytic and oxidative energy metabolic pathway enzymes. Correlations (all p < 0.05) were observed between maximal oxygen consumption (L.min-1) and body mass (r = 0.53), body mass index (r = 0.39), waist circumference (r = 0.34), fat free mass (FFM; r = 0.68), fat mass (r = 0.33), the enzyme activity of cytochrome c oxidase (COX; r = 0.39), muscle type IIA (r = 0.40) and IIX (r = 0.50) fiber area, and the number of capillaries per type IIA (r = 0.39) and IIX (r = 0.37) fiber. When adjusted for FFM in partial correlations, all correlations were lost, with the exception of COX (r = 0.48). Stepwise multiple regression revealed that maximal oxygen consumption was independently predicted by FFM, COX activity, mean capillary number per fiber, waist circumference, and, to a lesser extent, muscle capillary supply. In the absence of regular physical activity, cardiorespiratory fitness is strongly predicted by the potential for aerobic metabolism of skeletal muscle and negatively correlated with abdominal fat deposition.

Study of the Effect of Heat Supply on the Hydrodynamics of the Flow and Heat Transfer in Capillary Elements of Mixing Heads Jet Thrusters

NASA Astrophysics Data System (ADS)

Nigodjuk, V. E.; Sulinov, A. V.

2018-01-01

The article presents the results of experimental studies of hydrodynamics and those of loobman single-phase and two-phase flows in capillary nozzle elements propellant thrusters and the proposed method of their calculation. An experimental study was performed in capillaries with a sharp entrance edge of the internal diameter of 0.16 and 0.33 mm and a relative length 188 and 161, respectively, in pouring distilled water and acetone in the following range of parameters Reynolds number Re = (0,3 ... 10) · 103, Prandtl number Pr = (2 ... 10), pressure p = (0,1 ... 0,3) MPa, the heat flux q = (0...2)×106 W/m2, the difference of temperature under-heating of liquid Δtn = (5 ... 80)K. The dependences for calculation of single phase boundaries, the undeveloped and the developed surface of the bubble and film key singing of subcooled liquid. It is shown theoretically and experimentally confirmed the virtual absence of areas of undeveloped nucleate boiling in laminar flow. The dependence for calculation of hydraulic resistance and heat transfer in the investigated areas of current. It is shown that in the region of nucleate boiling surface in the flow in capillary tubes, influence of the formed vapor phase on the hydrodynamics and heat transfer substantially higher than in larger diameter pipes.

The Performance and Usability of a Factory-Calibrated Flash Glucose Monitoring System

PubMed Central

Bailey, Timothy; Bode, Bruce W.; Christiansen, Mark P.; Klaff, Leslie J.

2015-01-01

Abstract Introduction: The purpose of the study was to evaluate the performance and usability of the FreeStyle® Libre™ Flash glucose monitoring system (Abbott Diabetes Care, Alameda, CA) for interstitial glucose results compared with capillary blood glucose results. Materials and Methods: Seventy-two study participants with type 1 or type 2 diabetes were enrolled by four U.S. clinical sites. A sensor was inserted on the back of each upper arm for up to 14 days. Three factory-only calibrated sensor lots were used in the study. Sensor glucose measurements were compared with capillary blood glucose (BG) results (approximately eight per day) obtained using the BG meter built into the reader (BG reference) and with the YSI analyzer (Yellow Springs Instrument, Yellow Springs, OH) reference tests at three clinic visits (32 samples per visit). Sensor readings were masked to the participants. Results: The accuracy of the results was demonstrated against capillary BG reference values, with 86.7% of sensor results within Consensus Error Grid Zone A. The percentage of readings within Consensus Error Grid Zone A on Days 2, 7, and 14 was 88.4%, 89.2%, and 85.2%, respectively. The overall mean absolute relative difference was 11.4%. The mean lag time between sensor and YSI reference values was 4.5±4.8 min. Sensor accuracy was not affected by factors such as body mass index, age, type of diabetes, clinical site, insulin administration, or hemoglobin A1c. Conclusions: Interstitial glucose measurements with the FreeStyle Libre system were found to be accurate compared with capillary BG reference values, with accuracy remaining stable over 14 days of wear and unaffected by patient characteristics. PMID:26171659

Optical coherence tomography angiography discerns preclinical diabetic retinopathy in eyes of patients with type 2 diabetes without clinical diabetic retinopathy.

PubMed

Cao, Dan; Yang, Dawei; Huang, Zhongning; Zeng, Yunkao; Wang, Jun; Hu, Yunyan; Zhang, Liang

2018-05-01

To investigate changes in retinal vascular plexuses and choriocapillaris in patients with type 2 diabetes mellitus (DM2) without diabetic retinopathy (DR) and healthy controls using optical coherence tomography angiography (OCTA). A total of 71 DM2 and 67 healthy control subjects were included. All subjects underwent OCTA examination (RTVue-XR Avanti; Optovue, Fremont, CA, USA). Average vessel density in superficial capillary plexus (SCP), deep capillary plexus (DCP) and choriocapillaris, parafoveal vessel density in SCP and DCP, FAZ area (mm 2 ) in SCP, microaneurysms and capillary nonperfusion were taken into analysis. Parafoveal vessel density in both SCP and DCP decreased in the eyes without clinical DR compared to normal controls (p < 0.001). Diabetic patients with no signs of DR also had a significant reduction in average vessel density of SCP, DCP and choriocapillaris (p < 0.001, p < 0.001 and p = 0.006, respectively). No significant difference was found in FAZ area of SCP between DM2 eyes and healthy controls (p = 0.253). The average vessel density of SCP and DCP is not correlated with HbA1c or serum creatinine in DM2 patients. Microaneurysms seen in OCTA but not in fundus examination were found in 8 out of the 71 (11.3%) diabetic eyes, and capillary nonperfusion was noted in 18 of 71 diabetic eyes. We demonstrated that OCTA can identify preclinical DR before the manifestation of clinically apparent retinopathy in diabetic eyes. DM2 patients without DR have SCP, DCP and choriocapillaris impairment. Our results suggested that OCTA might be a promising tool for regular screening of diabetic eyes for DR.

The Performance and Usability of a Factory-Calibrated Flash Glucose Monitoring System.

PubMed

Bailey, Timothy; Bode, Bruce W; Christiansen, Mark P; Klaff, Leslie J; Alva, Shridhara

2015-11-01

The purpose of the study was to evaluate the performance and usability of the FreeStyle(®) Libre™ Flash glucose monitoring system (Abbott Diabetes Care, Alameda, CA) for interstitial glucose results compared with capillary blood glucose results. Seventy-two study participants with type 1 or type 2 diabetes were enrolled by four U.S. clinical sites. A sensor was inserted on the back of each upper arm for up to 14 days. Three factory-only calibrated sensor lots were used in the study. Sensor glucose measurements were compared with capillary blood glucose (BG) results (approximately eight per day) obtained using the BG meter built into the reader (BG reference) and with the YSI analyzer (Yellow Springs Instrument, Yellow Springs, OH) reference tests at three clinic visits (32 samples per visit). Sensor readings were masked to the participants. The accuracy of the results was demonstrated against capillary BG reference values, with 86.7% of sensor results within Consensus Error Grid Zone A. The percentage of readings within Consensus Error Grid Zone A on Days 2, 7, and 14 was 88.4%, 89.2%, and 85.2%, respectively. The overall mean absolute relative difference was 11.4%. The mean lag time between sensor and YSI reference values was 4.5±4.8 min. Sensor accuracy was not affected by factors such as body mass index, age, type of diabetes, clinical site, insulin administration, or hemoglobin A1c. Interstitial glucose measurements with the FreeStyle Libre system were found to be accurate compared with capillary BG reference values, with accuracy remaining stable over 14 days of wear and unaffected by patient characteristics.

Comparative morphometry of fibers and capillaries in soleus following weightlessness (SL-3) and suspension

NASA Technical Reports Server (NTRS)

Musacchia, X. J.; Steffen, Joseph M.; Fell, R. D.; Dombrowski, M. J.

1988-01-01

This work is a continuation of efforts to assess responses of rat skeletal muscle to weightlessness (W) and earthside laboratory experiments with unloading of hind limbs. The soleus is a slow-twitch, load-bearing (antigravity) muscle. Both exposure to W and to the hypokinesia/hypodynamia of whole-body suspension (WBS) results in soleus atrophy. Cross-sectional areas of both slow- and fast-twitch fibers decrease during 7 days of W or 7 or 14 days of WBS. Density and area changes tended to reverse to control levels during 7 days of recovery (R) following WBS. Capillary density was increased with 7 days of W or 7 or 14 days of WBS. During 7 days of R the capillary density returned toward control levels. In summary, the reduction in fiber cross-sectional areas and the increase in fiber and capillary densities support the hypothesis that in both W and WBS there is a loss in soleus muscle cell mass and not in fiber numbers.

Microfluidic step-emulsification in a cylindrical geometry

NASA Astrophysics Data System (ADS)

Chakraborty, Indrajit; Leshansky, Alexander M.

2016-11-01

The model microfluidic device for high-throughput droplet generation in a confined cylindrical geometry is investigated numerically. The device comprises of core-annular pressure-driven flow of two immiscible viscous liquids through a cylindrical capillary connected co-axially to a tube of a larger diameter through a sudden expansion, mimicking the microfluidic step-emulsifier (1). To study this problem, the numerical simulations of axisymmetric Navier-Stokes equations have been carried out using an interface capturing procedure based on coupled level set and volume-of-fluid (CLSVOF) methods. The accuracy of the numerical method was favorably tested vs. the predictions of the linear stability analysis of core-annular two-phase flow in a cylindrical capillary. Three distinct flow regimes can be identified: the dripping (D) instability near the entrance to the capillary, the step- (S) and the balloon- (B) emulsification at the step-like expansion. Based on the simulation results we present the phase diagram quantifying transitions between various regimes in plane of the capillary number and the flow-rate ratio. MICROFLUSA EU H2020 project.

Gas-filled capillaries for plasma-based accelerators

NASA Astrophysics Data System (ADS)

Filippi, F.; Anania, M. P.; Brentegani, E.; Biagioni, A.; Cianchi, A.; Chiadroni, E.; Ferrario, M.; Pompili, R.; Romeo, S.; Zigler, A.

2017-07-01

Plasma Wakefield Accelerators are based on the excitation of large amplitude plasma waves excited by either a laser or a particle driver beam. The amplitude of the waves, as well as their spatial dimensions and the consequent accelerating gradient depend strongly on the background electron density along the path of the accelerated particles. The process needs stable and reliable plasma sources, whose density profile must be controlled and properly engineered to ensure the appropriate accelerating mechanism. Plasma confinement inside gas filled capillaries have been studied in the past since this technique allows to control the evolution of the plasma, ensuring a stable and repeatable plasma density distribution during the interaction with the drivers. Moreover, in a gas filled capillary plasma can be pre-ionized by a current discharge to avoid ionization losses. Different capillary geometries have been studied to allow the proper temporal and spatial evolution of the plasma along the acceleration length. Results of this analysis obtained by varying the length and the number of gas inlets will be presented.

Gas Flow and Ion Transfer in Heated ESI Capillary Interfaces

NASA Astrophysics Data System (ADS)

Bernier, Laurent; Pinfold, Harry; Pauly, Matthias; Rauschenbach, Stephan; Reiss, Julius

2018-02-01

Transfer capillaries are the preferred means to transport ions, generated by electrospray ionization, from ambient conditions to vacuum. During the transfer of ions through the narrow, long tubes into vacuum, substantial losses are typical. However, recently it was demonstrated that these losses can be avoided altogether. To understand the experimental observation and provide a general model for the ion transport, here, we investigate the ion transport through capillaries by numerical simulation of interacting ions. The simulation encompasses all relevant factors, such as space charge, diffusion, gas flow, and heating. Special attention is paid to the influence of the gas flow on the transmission and especially the change imposed by heating. The gas flow is modeled by a one-dimensional gas dynamics description. A large number of ions are treated as point particles in this gas flow. This allows to investigate the influence of the capillary heating on the gas flow and by this on the ion transport. The results are compared with experimental findings. [Figure not available: see fulltext.

Techniques for Measuring Solubility and Electrical Conductivity in Molten Salts

NASA Astrophysics Data System (ADS)

Su, Shizhao; Villalon, Thomas; Pal, Uday; Powell, Adam

Eutectic MgF2-CaF2 based salt containing YF3, CaO and Al2O3 additions were used in this study. The electrical conductivity was measured as a function of temperature by a calibration-free coaxial electrode setup. The materials selection and setup design were optimized to accurately measure the electrical conductivity of the highly conductive molten salts (>1 S/cm). The solubility and diffusion behavior of alumina and zirconia in the molten salts were investigated by drawing and holding the molten salt for different lengths of time within capillary tubes made of alumina and zirconia, respectively. After the time-dependent high temperature holds, the samples were cooled and the solubility of the solute within the molten salt was determined using scanning electron microscopy, energy-dispersive X-ray spectroscopy analysis and wavelength-dispersive X-ray spectroscopy analysis.

Implementation of digital optical capillaroscopy for quantifying and estimating the microvascular abnormalities in type 2 diabetes mellitus

NASA Astrophysics Data System (ADS)

Gurfinkel, Yu. I.; Suchkova, O. V.; Sasonko, M. L.; Priezzhev, A. V.

2016-04-01

This study is aimed to define the extent of digital capillaroscopy possibilities for the quantification and estimation of microvascular abnormalities in type 2 diabetes mellitus (T2DM). A total of 196 adult persons were enrolled in the study including the group of compensated T2DM (n = 52), decompensated diabetics (n = 68), and healthy volunteers (n = 76) with normal blood glucose and without signs of cardiovascular pathology. All participants of the study were examined with the digital optical capillaroscope ("AET", Russia). This instrument is equipped with an image-processing program allowing for quantifying the diameters of the arterial and venous segments of the capillaries and their ratio (coefficient of remodeling), perivascular zone size, capillary blood velocity, and the degree of arterial loops narrowing and the density of the capillary network. Also we estimated the relative amount of coil-shaped capillaries. The study revealed significant difference in the capillary density and the remodeling coefficient in comparison of T2DM patients with non-diabetic individuals. Significant changes are found in the decompensated T2DM group compared to the compensated group of diabetic patients. Furthermore, the number of coil-shaped capillaries differed greatly in T2DM patients as compared to the healthy subjects. The study did not reveal any statistically significant differences in the capillary density between the patients with compensated and decompensated T2DM. The digital optical capillaroscope equipped with the advanced image-processing algorithm opens up new possibilities for obtaining clinically important information on microvascular abnormalities in patients suffering from diabetes mellitus.

Molecular transport through capillaries made with atomic-scale precision

NASA Astrophysics Data System (ADS)

Radha, B.; Esfandiar, A.; Wang, F. C.; Rooney, A. P.; Gopinadhan, K.; Keerthi, A.; Mishchenko, A.; Janardanan, A.; Blake, P.; Fumagalli, L.; Lozada-Hidalgo, M.; Garaj, S.; Haigh, S. J.; Grigorieva, I. V.; Wu, H. A.; Geim, A. K.

2016-10-01

Nanometre-scale pores and capillaries have long been studied because of their importance in many natural phenomena and their use in numerous applications. A more recent development is the ability to fabricate artificial capillaries with nanometre dimensions, which has enabled new research on molecular transport and led to the emergence of nanofluidics. But surface roughness in particular makes it challenging to produce capillaries with precisely controlled dimensions at this spatial scale. Here we report the fabrication of narrow and smooth capillaries through van der Waals assembly, with atomically flat sheets at the top and bottom separated by spacers made of two-dimensional crystals with a precisely controlled number of layers. We use graphene and its multilayers as archetypal two-dimensional materials to demonstrate this technology, which produces structures that can be viewed as if individual atomic planes had been removed from a bulk crystal to leave behind flat voids of a height chosen with atomic-scale precision. Water transport through the channels, ranging in height from one to several dozen atomic planes, is characterized by unexpectedly fast flow (up to 1 metre per second) that we attribute to high capillary pressures (about 1,000 bar) and large slip lengths. For channels that accommodate only a few layers of water, the flow exhibits a marked enhancement that we associate with an increased structural order in nanoconfined water. Our work opens up an avenue to making capillaries and cavities with sizes tunable to ångström precision, and with permeation properties further controlled through a wide choice of atomically flat materials available for channel walls.

Investigation and visualization of liquid-liquid flow in a vertically mounted Hele-Shaw cell: flow regimes, velocity and shape of droplets

NASA Astrophysics Data System (ADS)

Shad, S.; Gates, I. D.; Maini, B. B.

2009-11-01

The motion and shape of a liquid drop flowing within a continuous, conveying liquid phase in a vertical Hele-Shaw cell were investigated experimentally. The continuous phase was more viscous and wetted the bounding walls of the Hele-Shaw cell. The gap between the Hele-Shaw plates was set equal to 0.0226 cm. Four different flow regimes were observed: (a) small-droplet flow, (b) elongated-droplet flow, (c) churn flow and (d) channel flow. At low capillary number, that is, when capillary forces are larger than viscous forces, the droplet shape was irregular and changed with time and distance, and it moved with lower velocity than that of the conveying phase. At higher capillary number, several different shapes of stabilized elongated and flattened drops were observed. In contrast to gas-liquid systems, the velocities of droplets are higher than that of conveying liquid. New correlations derived from dimensionless analysis and fitted to the experimental data were generated to predict the elongated-drop velocity and aspect ratio.

Optimization of post-column reactor radius in capillary high performance liquid chromatography Effect of chromatographic column diameter and particle diameter

PubMed Central

Xu, Hongjuan; Weber, Stephen G.

2006-01-01

A post-column reactor consisting of a simple open tube (Capillary Taylor Reactor) affects the performance of a capillary LC in two ways: stealing pressure from the column and adding band spreading. The former is a problem for very small radius reactors, while the latter shows itself for large reactor diameters. We derived an equation that defines the observed number of theoretical plates (Nobs) taking into account the two effects stated above. Making some assumptions and asserting certain conditions led to a final equation with a limited number of variables, namely chromatographic column radius, reactor radius and chromatographic particle diameter. The assumptions and conditions are that the van Deemter equation applies, the mass transfer limitation is for intraparticle diffusion in spherical particles, the velocity is at the optimum, the analyte’s retention factor, k′, is zero, the post-column reactor is only long enough to allow complete mixing of reagents and analytes and the maximum operating pressure of the pumping system is used. Optimal ranges of the reactor radius (ar) are obtained by comparing the number of observed theoretical plates (and theoretical plates per time) with and without a reactor. Results show that the acceptable reactor radii depend on column diameter, particle diameter, and maximum available pressure. Optimal ranges of ar become narrower as column diameter increases, particle diameter decreases or the maximum pressure is decreased. When the available pressure is 4000 psi, a Capillary Taylor Reactor with 12 μm radius is suitable for all columns smaller than 150 μm (radius) packed with 2–5 μm particles. For 1 μm packing particles, only columns smaller than 42.5 μm (radius) can be used and the reactor radius needs to be 5 μm. PMID:16494886

Production of microbubbles from axisymmetric flow focusing in the jetting regime for moderate Reynolds numbers.

PubMed

Vega, E J; Acero, A J; Montanero, J M; Herrada, M A; Gañán-Calvo, A M

2014-06-01

We analyze both experimentally and numerically the formation of microbubbles in the jetting regime reached when a moderately viscous liquid stream focuses a gaseous meniscus inside a converging micronozzle. If the total (stagnation) pressure of the injected gas current is fixed upstream, then there are certain conditions on which a quasisteady gas meniscus forms. The meniscus tip is sharpened by the liquid stream down to the gas molecular scale. On the other side, monodisperse collections of microbubbles can be steadily produced in the jetting regime if the feeding capillary is appropriately located inside the nozzle. In this case, the microbubble size depends on the feeding capillary position. The numerical simulations for an imposed gas flow rate show that a recirculation cell appears in the gaseous meniscus for low enough values of that parameter. The experiments allow one to conclude that the bubble pinch-off comprises two phases: (i) a stretching motion of the precursor jet where the neck radius versus the time before the pinch essentially follows a potential law, and (ii) a final stage where a very thin and slender gaseous thread forms and eventually breaks apart into a number of micron-sized bubbles. Because of the difference between the free surface and core velocities, the gaseous jet breakage differs substantially from that of liquid capillary jets and gives rise to bubbles with diameters much larger than those expected from the Rayleigh-type capillary instability. The dependency of the bubble diameter upon the flow-rate ratio agrees with the scaling law derived by A. M. Gañán-Calvo [Phys. Rev. E 69, 027301 (2004)], although a slight influence of the Reynolds number can be observed in our experiments.

SITES OF LIPOPROTEIN LIPASE ACTIVITY IN ADIPOSE TISSUE PERFUSED WITH CHYLOMICRONS

PubMed Central

Blanchette-Mackie, E. Joan; Scow, Robert O.

1971-01-01

Lipoprotein lipase activity was studied in rat parametrial adipose tissue perfused with chylomicrons and in gelatin blocks containing postheparin plasma and chylomicrons. The tissues and blocks were fixed in glutaraldehyde and incubated in 0.035 M CaCl2-0.1 M Tris medium (pH 8.3) at 38°C. The doubly labeled chylomicron triglycerides (glycerol-3H and palmitate-14C) in the tissues and blocks were hydrolyzed during incubation to free fatty acids (FFA) and the FFA remained in the specimens; hydrolysis was inhibited by 0.004 M diethyl paranitrophenyl phosphate (E-600). Incubated blocks and tissue were treated with 0.05 M Pb(NO3)2, postfixed in OsO4, dehydrated with acetone, embedded in Epon, and examined by electron microscopy. The incubated blocks contained electronlucent areas and granular and laminar precipitates at sites of hydrolysis. Similar precipitates were found in incubated tissue, within vacuoles and microvesicles of capillary endothelium, and in the subendothelial space (between the endothelium and pericytes), but not in the capillary lumen or in or near fat cells. The cytochemical reaction was greatly reduced, in blocks and tissues incubated with E-600. It is concluded that plasma glycerides are hydrolyzed by lipoprotein lipase in capillary endothelial cells and in the subendothelial space of adipose tissue and that glycerides across the endothelial cells within a membrane-bounded system. PMID:4329521

Relative accuracy of the BD Logic and FreeStyle blood glucose meters.

PubMed

2007-04-01

The BD Logic((R)) (Becton, Dickinson and Co., Franklin Lakes, NJ) and FreeStyle((R)) (Abbott Diabetes Care, Alameda, CA) meters are used to transmit data directly to insulin pumps for calculation of insulin doses and to calibrate continuous glucose sensors as well as to monitor blood glucose levels. The accuracy of the two meters was evaluated in two inpatient studies conducted by the Diabetes Research in Children Network (DirecNet). In both studies, meter glucose measurements made with either venous or capillary blood were compared with reference glucose measurements made by the DirecNet Central Laboratory at the University of Minnesota using a hexokinase enzymatic method. The BD Logic tended to read lower than the laboratory reference regardless of whether venous (median difference = -9 mg/dL) or capillary blood (median difference = -7 mg/dL) was used. This resulted in lower accuracy of the BD Logic compared with the FreeStyle meter based on the median relative absolute difference (RAD) for both venous blood (median RAD, 9% vs. 5%, P < 0.001) and capillary blood (median RAD, 11% vs. 6%, P = 0.008). The greatest discrepancy in the performance of the two meters was at higher reference glucose values. Accuracy was not significantly different when the reference was < or = 70 mg/dL. The BD Logic meter is less accurate than the FreeStyle meter.

Enantioselective column coupled electrophoresis employing large bore capillaries hyphenated with tandem mass spectrometry for ultra-trace determination of chiral compounds in complex real samples.

PubMed

Piešťanský, Juraj; Maráková, Katarína; Kovaľ, Marián; Havránek, Emil; Mikuš, Peter

2015-12-01

A new multidimensional analytical approach for the ultra-trace determination of target chiral compounds in unpretreated complex real samples was developed in this work. The proposed analytical system provided high orthogonality due to on-line combination of three different methods (separation mechanisms), i.e. (1) isotachophoresis (ITP), (2) chiral capillary zone electrophoresis (chiral CZE), and (3) triple quadrupole mass spectrometry (QqQ MS). The ITP step, performed in a large bore capillary (800 μm), was utilized for the effective sample pretreatment (preconcentration and matrix clean-up) in a large injection volume (1-10 μL) enabling to obtain as low as ca. 80 pg/mL limits of detection for the target enantiomers in urine matrices. In the chiral CZE step, the different chiral selectors (neutral, ionizable, and permanently charged cyclodextrins) and buffer systems were tested in terms of enantioselectivity and influence on the MS detection response. The performance parameters of the optimized ITP - chiral CZE-QqQ MS method were evaluated according to the FDA guidance for bioanalytical method validation. Successful validation and application (enantioselective monitoring of renally eliminated pheniramine and its metabolite in human urine) highlighted great potential of this chiral approach in advanced enantioselective biomedical applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Oil/water displacement in microfluidic packed beds under weakly water-wetting conditions: competition between precursor film flow and piston-like displacement

NASA Astrophysics Data System (ADS)

Tanino, Yukie; Zacarias-Hernandez, Xanat; Christensen, Magali

2018-02-01

Optical microscopy was used to measure depth-averaged oil distribution in a quasi-monolayer of crushed marble packed in a microfluidic channel as it was displaced by water. By calibrating the transmitted light intensity to oil thickness, we account for depth variation in the fluid distribution. Experiments reveal that oil saturation at water breakthrough decreases with increasing Darcy velocity, U_{ {w}}, between capillary numbers {Ca} = μ _{ {w}} U_{ {w}}/σ = 9× 10^{-7} and 9× 10^{-6}, where μ _{ {w}} is the dynamic viscosity of water and σ is the oil/water interfacial tension, under the conditions considered presently. In contrast, end-point (long-time) remaining oil saturation depends only weakly on U_{ {w}}. This transient dependence on velocity is attributed to the competition between precursor film flow, which controls early time invasion dynamics but is inefficient at displacing oil, and piston-like displacement, which controls ultimate oil recovery. These results demonstrate that microfluidic experiments using translucent grains and fluids are a convenient tool for quantitative investigation of sub-resolution liquid/liquid displacement in porous media.

A temperature-tolerant multiplex elements and genes screening system for genetically modified organisms based on dual priming oligonucleotide primers and capillary electrophoresis.

PubMed

Fu, Wei; Wei, Shuang; Wang, Chenguang; Du, Zhixin; Zhu, Pengyu; Wu, Xiyang; Wu, Gang; Zhu, Shuifang

2017-08-15

High throughput screening systems are the preferred solution to meet the urgent requirement of increasing number of genetically modified organisms (GMOs). In this study, we have successfully developed a multiplex GMO element screening system with dual priming oligonucleotide (DPO) primers. This system can detect the cauliflower mosaic virus 35S (CaMV 35S), terminator of nopaline synthase gene (NOS), figwort mosaic virus 35S (FMV 35S) promoter, neomycin phosphotransferaseII (NPTII), Bt Cry 1Ab, phosphinothricin acetyltransferase genes (bar) and Streptomyces viridochromogenes (pat) simultaneously, which covers more than 90% of all authorized GMO species worldwide. This system exhibits a high tolerance to annealing temperatures, high specificity and a limit of detection equal to conventional PCR. A total of 214 samples from markets, national entry-exit agencies, the Institute for Reference Materials and Measurement (IRMM) and the American Oil Chemists' Society (AOCS) were also tested for applicability. This screening system is therefore suitable for GMO screening. Copyright © 2017 Elsevier Ltd. All rights reserved.

Intermittent whole-body vibration attenuates a reduction in the number of the capillaries in unloaded rat skeletal muscle.

PubMed

Kaneguchi, Akinori; Ozawa, Junya; Kawamata, Seiichi; Kurose, Tomoyuki; Yamaoka, Kaoru

2014-09-26

Whole-body vibration has been suggested for the prevention of muscle mass loss and muscle wasting as an attractive measure for disuse atrophy. This study examined the effects of daily intermittent whole-body vibration and weight bearing during hindlimb suspension on capillary number and muscle atrophy in rat skeletal muscles. Sixty male Wistar rats were randomly divided into four groups: control (CONT), hindlimb suspension (HS), HS + weight bearing (WB), and HS + whole-body vibration (VIB) (n = 15 each). Hindlimb suspension was applied for 2 weeks in HS, HS + WB, and HS + VIB groups. During suspension, rats in HS + VIB group were placed daily on a vibrating whole-body vibration platform for 20 min. In HS + WB group, suspension was interrupted for 20 min/day, allowing weight bearing. Untreated rats were used as controls. Soleus muscle wet weights and muscle fiber cross-sectional areas (CSA) significantly decreased in HS, HS + WB, and HS + VIB groups compared with CONT group. Both muscle weights and CSA were significantly greater in HS + WB and HS + VIB groups compared with HS group. Capillary numbers (represented by capillary-to-muscle fiber ratio) were significantly smaller in all hindlimb suspension-treated groups compared with CONT group. However, a reduction in capillary number by unloading hindlimbs was partially prevented by whole-body vibration. These findings were supported by examining mRNA for angiogenic-related factors. Expression levels of a pro-angiogenic factor, vascular endothelial growth factor-A mRNA, were significantly lower in all hindlimb suspension-treated groups compared with CONT group. There were no differences among hindlimb suspension-treated groups. Expression levels of an anti-angiogenic factor, CD36 (receptor for thrombospondin-1) mRNA, were significantly higher in all hindlimb suspension-treated groups compared with CONT group. Among the hindlimb suspension-treated groups, expression of CD36 mRNA in HS + VIB group tended to be suppressed (less than half the HS group). Our results suggest that weight bearing with or without vibration is effective for disuse-derived disturbance by preventing muscle atrophy, and whole-body vibration exercise has an additional benefit of maintaining microcirculation of skeletal muscle.

The Hæmorrhagic Diathesis

PubMed Central

Tidy, H. Letheby

1928-01-01

The primary purpuras form a single clinical entity. Variations in the number of platelets can occur without the production of hæmorrhages. These variations are the result of the condition of the capillaries and are not the cause of hæmorrhages. The platelets may vary in any form of purpura, primary or secondary. The essential cause of the hæmorrhagic state is a defect or increased permeability of the capillary endothelium. Purpura is allied to urticaria, the Henoch-Schönlein type being an intermediate state. PMID:19986460

Contact Line Instability Caused by Air Rim Formation under Nonsplashing Droplets.

PubMed

Pack, Min; Kaneelil, Paul; Kim, Hyoungsoo; Sun, Ying

2018-05-01

Drop impact is fundamental to various natural and industrial processes such as rain-induced soil erosion and spray-coating technologies. The recent discovery of the role of air entrainment between the droplet and the impacting surface has produced numerous works, uncovering the unique physics that correlates the air film dynamics with the drop impact outcomes. In this study, we focus on the post-failure air entrainment dynamics for We numbers well below the splash threshold under different ambient pressures and elucidate the interfacial instabilities formed by air entrainment at the wetting front of impacting droplets on perfectly smooth, viscous films of constant thickness. A high-speed total internal reflection microscopy technique accounting for the Fresnel reflection at the drop-air interface allows for in situ measurements of an entrained air rim at the wetting front. The presence of an air rim is found to be a prerequisite to the interfacial instability which is formed when the capillary pressure in the vicinity of the contact line can no longer balance the increasing gas pressure near the wetting front. A critical capillary number for the air rim formation is experimentally identified above which the wetting front becomes unstable where this critical capillary number inversely scales with the ambient pressure. The contact line instabilities at relatively low We numbers ( We ∼ O(10)) observed in this study provide insight into the conventional understanding of hydrodynamic instabilities under drop impact which usually require We ≫ 10.

Galpha13 regulates MEF2-dependent gene transcription in endothelial cells: role in angiogenesis.

PubMed

Liu, Guoquan; Han, Jingyan; Profirovic, Jasmina; Strekalova, Elena; Voyno-Yasenetskaya, Tatyana A

2009-01-01

The alpha subunit of heterotrimeric G13 protein is required for the embryonic angiogenesis (Offermanns et al., Science 275:533-536, 1997). However, the molecular mechanism of Galpha13-dependent angiogenesis is not understood. Here, we show that myocyte-specific enhancer factor-2 (MEF2) mediates Galpha13-dependent angiogenesis. Our data showed that constitutively activated Galpha13Q226L stimulated MEF2-dependent gene transcription. In addition, downregulation of endogenous Galpha13 inhibited thrombin-stimulated MEF2-dependent gene transcription in endothelial cells. Both Ca(2+)/calmodulin-dependent kinase IV (CaMKIV) and histone deacetylase 5 (HDAC5) were involved in Galpha13-mediated MEF2-dependent gene transcription. Galpha13Q226L also increased Ca(2+)/calmodulin-independent CaMKIV activity, while dominant negative mutant of CaMKIV inhibited MEF2-dependent gene transcription induced by Galpha13Q226L. Furthermore, Galpha13Q226L was able to derepress HDAC5-mediated repression of gene transcription and induce the translocation of HDAC5 from nucleus to cytoplasm. Finally, downregulation of endogenous Galpha13 and MEF2 proteins in endothelial cells reduced cell proliferation and capillary tube formation. Decrease of endothelial cell proliferation that was caused by the Galpha13 downregulation was partially restored by the constitutively active MEF2-VP16. Our studies suggest that MEF2 proteins are an important component in Galpha13-mediated angiogenesis.

Characterization of a Vesivirus Associated with an Outbreak of Acute Hemorrhagic Gastroenteritis in Domestic Dogs.

PubMed

Renshaw, Randall W; Griffing, Jennifer; Weisman, Jaime; Crofton, Lisa M; Laverack, Melissa A; Poston, Robert P; Duhamel, Gerald E; Dubovi, Edward J

2018-05-01

Four of eleven affected dogs died despite aggressive treatment during a 2015 focal outbreak of hemorrhagic gastroenteritis following a stay in a pet housing facility. Routine diagnostic investigations failed to identify a specific cause. Virus isolation from fresh necropsy tissues yielded a calicivirus with sequence homology to a vesivirus within the group colloquially known as the vesivirus 2117 strains that were originally identified as contaminants in CHO cell bioreactors. In situ hybridization and reverse transcription-PCR assays of tissues from the four deceased dogs confirmed the presence of canine vesivirus (CaVV) nucleic acids that localized to endothelial cells of arterial and capillary blood vessels. CaVV nucleic acid corresponded to areas of necrosis and hemorrhage primarily in the intestinal tract, but also in the brain of one dog with nonsuppurative meningoencephalitis. This is the first report of an atypical disease association with a putative hypervirulent vesivirus strain in dogs, as all other known strains of CaVV appear to cause nonclinical infections or relatively mild disease. After identification of the CU-296 vesivirus strain from this outbreak, four additional CaVV strains were amplified from unrelated fecal specimens and archived stocks provided by other laboratories. Broader questions include the origins, reservoir(s), and potential for reemergence and spread of these related CaVVs. Copyright © 2018 American Society for Microbiology.

Brain microvascular function during cardiopulmonary bypass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sorensen, H.R.; Husum, B.; Waaben, J.

1987-11-01

Emboli in the brain microvasculature may inhibit brain activity during cardiopulmonary bypass. Such hypothetical blockade, if confirmed, may be responsible for the reduction of cerebral metabolic rate for glucose observed in animals subjected to cardiopulmonary bypass. In previous studies of cerebral blood flow during bypass, brain microcirculation was not evaluated. In the present study in animals (pigs), reduction of the number of perfused capillaries was estimated by measurements of the capillary diffusion capacity for hydrophilic tracers of low permeability. Capillary diffusion capacity, cerebral blood flow, and cerebral metabolic rate for glucose were measured simultaneously by the integral method, different tracersmore » being used with different circulation times. In eight animals subjected to normothermic cardiopulmonary bypass, and seven subjected to hypothermic bypass, cerebral blood flow, cerebral metabolic rate for glucose, and capillary diffusion capacity decreased significantly: cerebral blood flow from 63 to 43 ml/100 gm/min in normothermia and to 34 ml/100 gm/min in hypothermia and cerebral metabolic rate for glucose from 43.0 to 23.0 mumol/100 gm/min in normothermia and to 14.1 mumol/100 gm/min in hypothermia. The capillary diffusion capacity declined markedly from 0.15 to 0.03 ml/100 gm/min in normothermia but only to 0.08 ml/100 gm/min in hypothermia. We conclude that the decrease of cerebral metabolic rate for glucose during normothermic cardiopulmonary bypass is caused by interruption of blood flow through a part of the capillary bed, possibly by microemboli, and that cerebral blood flow is an inadequate indicator of capillary blood flow. Further studies must clarify why normal microvascular function appears to be preserved during hypothermic cardiopulmonary bypass.« less

Nitric oxide enhances angiogenesis via the synthesis of vascular endothelial growth factor and cGMP after stroke in the rat.

PubMed

Zhang, Ruilan; Wang, Lei; Zhang, Li; Chen, Jieli; Zhu, Zhenping; Zhang, Zhenggang; Chopp, Michael

2003-02-21

We investigated the effects of NO on angiogenesis and the synthesis of vascular endothelial growth factor (VEGF) in a model of focal embolic cerebral ischemia in the rat. Compared with control rats, systemic administration of an NO donor, DETANONOate, to rats 24 hours after stroke significantly enlarged vascular perimeters and increased the number of proliferated cerebral endothelial cells and the numbers of newly generated vessels in the ischemic boundary regions, as evaluated by 3-dimensional laser scanning confocal microscopy. Treatment with DETANONOate significantly increased VEGF levels in the ischemic boundary regions as measured by ELISA. A capillary-like tube formation assay was used to investigate whether DETANONOate increases angiogenesis in ischemic brain via activation of soluble guanylate cyclase. DETANONOate-induced capillary-like tube formation was completely inhibited by a soluble guanylate cyclase inhibitor, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxaline-1-one (ODQ). Blocking VEGF activity by a neutralized antibody against VEGF receptor 2 significantly attenuated DETANONOate-induced capillary-like tube formation. Moreover, systemic administration of a phosphodiesterase type 5 inhibitor (Sildenafil) to rats 24 hours after stroke significantly increased angiogenesis in the ischemic boundary regions. Sildenafil and an analog of cyclic guanosine monophosphate (cGMP) also induced capillary-like tube formation. These findings suggest that exogenous NO enhances angiogenesis in ischemic brain, which is mediated by the NO/cGMP pathway. Furthermore, our data suggest that NO, in part via VEGF, may enhance angiogenesis in ischemic brain.

Core analysis of heterogeneous rocks using experimental observations and digital whole core simulation

NASA Astrophysics Data System (ADS)

Jackson, S. J.; Krevor, S. C.; Agada, S.

2017-12-01

A number of studies have demonstrated the prevalent impact that small-scale rock heterogeneity can have on larger scale flow in multiphase flow systems including petroleum production and CO2sequestration. Larger scale modeling has shown that this has a significant impact on fluid flow and is possibly a significant source of inaccuracy in reservoir simulation. Yet no core analysis protocol has been developed that faithfully represents the impact of these heterogeneities on flow functions used in modeling. Relative permeability is derived from core floods performed at conditions with high flow potential in which the impact of capillary heterogeneity is voided. A more accurate representation would be obtained if measurements were made at flow conditions where the impact of capillary heterogeneity on flow is scaled to be representative of the reservoir system. This, however, is generally impractical due to laboratory constraints and the role of the orientation of the rock heterogeneity. We demonstrate a workflow of combined observations and simulations, in which the impact of capillary heterogeneity may be faithfully represented in the derivation of upscaled flow properties. Laboratory measurements that are a variation of conventional protocols are used for the parameterization of an accurate digital rock model for simulation. The relative permeability at the range of capillary numbers relevant to flow in the reservoir is derived primarily from numerical simulations of core floods that include capillary pressure heterogeneity. This allows flexibility in the orientation of the heterogeneity and in the range of flow rates considered. We demonstrate the approach in which digital rock models have been developed alongside core flood observations for three applications: (1) A Bentheimer sandstone with a simple axial heterogeneity to demonstrate the validity and limitations of the approach, (2) a set of reservoir rocks from the Captain sandstone in the UK North Sea targeted for CO2 storage, and for which the use of capillary pressure hysteresis is necessary, and (3) a secondary CO2-EOR production of residual oil from a Berea sandstone with layered heterogeneities. In all cases the incorporation of heterogeneity is shown to be key to the ultimate derivation of flow properties representative of the reservoir system.

CLOVES syndrome: review of a PIK3CA-related overgrowth spectrum (PROS).

PubMed

Martinez-Lopez, A; Blasco-Morente, G; Perez-Lopez, I; Herrera-Garcia, J D; Luque-Valenzuela, M; Sanchez-Cano, D; Lopez-Gutierrez, J C; Ruiz-Villaverde, R; Tercedor-Sanchez, J

2017-01-01

Overgrowth syndromes are characterized by global or localized disproportionate growth associated with other anomalies, including vascular malformations and neurological and/or visceral disorders. CLOVES (Congenital Lipomatous asymmetric Overgrowth of the trunk with lymphatic, capillary, venous, and combined-type Vascular malformations, Epidermal naevi, Scoliosis/Skeletal and spinal anomalies) is an overgrowth syndrome caused by mosaic activating mutation in gene PIK3CA, which gives rise to abnormal PI3K-AKT-mTOR pathway activation. These mutations are responsible for the clinical manifestations of the syndrome, which include low- and high-flow vascular malformations, thoracic lipomatous hyperplasia, asymmetric growth, and visceral and neurological disorders. These common anomalies are illustrated with figures from two personal cases. Identification of the clinical and genetic characteristics of CLOVES syndrome is crucial for the differential diagnosis with other overgrowth syndromes, such as Proteus or Klippel-Trenaunay (K-T) syndromes, and for the therapeutic management of the different anomalies. In this context, a new entity comprising different syndromes with phenotypic mutations in PIK3CA has been proposed, designated PIK3CA-related overgrowth spectrum (PROS), with the aim of facilitating clinical management and establishing appropriate genetic study criteria. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Evaluation of the Chemical and Mechanical Properties of Hardening High-Calcium Fly Ash Blended Concrete

PubMed Central

Fan, Wei-Jie; Wang, Xiao-Yong; Park, Ki-Bong

2015-01-01

High-calcium fly ash (FH) is the combustion residue from electric power plants burning lignite or sub-bituminous coal. As a mineral admixture, FH can be used to produce high-strength concrete and high-performance concrete. The development of chemical and mechanical properties is a crucial factor for appropriately using FH in the concrete industry. To achieve sustainable development in the concrete industry, this paper presents a theoretical model to systematically evaluate the property developments of FH blended concrete. The proposed model analyzes the cement hydration, the reaction of free CaO in FH, and the reaction of phases in FH other than free CaO. The mutual interactions among cement hydration, the reaction of free CaO in FH, and the reaction of other phases in FH are also considered through the calcium hydroxide contents and the capillary water contents. Using the hydration degree of cement, the reaction degree of free CaO in FH, and the reaction degree of other phases in FH, the proposed model evaluates the calcium hydroxide contents, the reaction degree of FH, chemically bound water, porosity, and the compressive strength of hardening concrete with different water to binder ratios and FH replacement ratios. The evaluated results are compared to experimental results, and good consistencies are found. PMID:28793543

Considerations on the determination of the limit of detection and the limit of quantification in one-dimensional and comprehensive two-dimensional gas chromatography.

PubMed

Krupčík, Ján; Májek, Pavel; Gorovenko, Roman; Blaško, Jaroslav; Kubinec, Robert; Sandra, Pat

2015-05-29

Methods based on the blank signal as proposed by IUPAC procedure and on the signal to noise ratio (S/N) as listed in the ISO-11843-1 norm for determination of the limit of detection (LOD) and quantitation (LOQ) in one-dimensional capillary gas chromatography (1D-GC) and comprehensive two-dimensional capillary gas chromatography (CG×GC) are described in detail and compared for both techniques. Flame ionization detection was applied and variables were the data acquisition frequency and, for CG×GC, also the modulation time. It has been stated that LOD and LOQ estimated according to IUPAC might be successfully used for 1D-GC-FID method. Moreover, LOD and LOQ decrease with decrease of data acquisition frequency (DAF). For GC×GC-FID, estimation of LOD by IUPAC gave poor reproducibility of results while for LOQ reproducibility was acceptable (within ±10% rel.). The LOD and LOQ determined by the S/N concept both for 1D-GC-FID and GC×GC-FID methods are ca. three times higher than those values estimated by the standard deviation of the blank. Since the distribution pattern of modulated peaks for any analyte separated by GC×GC is random and cannot be predicted, LOQ and LOD may vary within 30% for 3s modulation time. Concerning sensitivity, 1D-GC-FID at 2Hz and of GC×GC-FID at 50Hz shows a ca. 5 times enhancement of sensitivity in the modulated signal output. Copyright © 2015 Elsevier B.V. All rights reserved.

An experimental investigation of bubble splitting through multiple bifurcations

NASA Astrophysics Data System (ADS)

Bull, Joseph L.; Eshpuniyani, Brijesh; Fowlkes, J. Brian

2004-11-01

A bench top vascular bifurcation model is used to investigate the splitting of long bubbles in a series of liquid-filled bifurcations. These experiments are motivated by a gas embolotherapy technique for the potential treatment of cancer by using gas emboli to infarct tumors. The gas bubbles originate as perfluorocarbon droplets that are small enough to pass through capillaries and are injected into the bloodstream. Low intensity ultrasound is used to track their motion, and they are vaporized at the desired location for treatment via high intensity ultrasound to produce gas bubbles whose volumes are approximately 125 to 150 times the droplet volume. Achieving complete tumor necrosis requires infarction of most of the tumor. Understanding the transport and splitting of the gas bubbles, which can be long enough to extend through more than one bifurcation, is necessary to design delivery strategies. The current experiments investigate the behavior of a bubble as it passes through a series of two geometrically symmetric bifurcations, for different values of effective Bond number, which depends on gravity and the positioning of the bifurcation, capillary number, and bubble volume. The experiments are designed to match the Reynolds, Bond and capillary numbers to the physiological values for arterioles, and to provide guidance in achieving uniform tumor infarction. This work is supported by NSF grant BES-0301278 and NIH grant EB003541-01.

Nailfold capillaroscopy abnormalities as predictors of mortality in patients with systemic sclerosis.

PubMed

Kayser, Cristiane; Sekiyama, Juliana Y; Próspero, Lucas C; Camargo, Cintia Z; Andrade, Luis E C

2013-01-01

Peripheral microangiopathy is a hallmark of systemic sclerosis (SSc) and can be early detected by nailfold capillaroscopy (NFC). This study aimed to examine whether more severe peripheral microangiopathy at NFC are predictive factor for death in SSc patients. 135 SSc patients who performed NFC between June 2001 and July 2009 were included. The following NFC parameters were evaluated: number of capillary loops/mm, avascular score (scored from 0 to 3), and number of enlarged and giant capillary loops. Univariate and multivariate regression models were used to analyse the association of mortality with NFC and clinical parameters. At the time of the analysis (August 2010), 123 patients were alive, and 12 were dead. By univariate analysis, male gender, forced vital capacity <75% predicted, higher number of giant capillary loops, and an avascular score >1.5 on NFC were associated with a significantly increase risk of death. By multivariate analysis, an avascular score >1.5 was the only independent predictor of death (hazard ratio 2.265). Survival rates from diagnosis at 1, 5 and 10 years were lower in patients with avascular score >1.5 (97%, 86%, and 59%, respectively) compared with those with avascular score ≤1.5 (97%, 97%, and 91% respectively) (p=0.009 by log rank test). Avascular scores higher than 1.5 at NFC was an independent predictor of death in SSc, suggesting that NFC can be useful for predicting SSc outcome.

Enrichment of Glycoproteins using Nano-scale Chelating Con A Monolithic Capillary Chromatography

PubMed Central

Feng, Shun; Yang, Na; Pennathur, Subramaniam; Goodison, Steve; Lubman, David M.

2009-01-01

Immobilized lectin chromatography can be employed for glycoprotein enrichment, but commonly used columns have limitations of yield and resolution. In order to improve efficiency and to make the technique applicable to minimal sample material, we have developed a nano-scale chelating Concanavalin A (Con A) monolithic capillary prepared using GMA-EDMA (glycidyl methacrylate–co-ethylene dimethacrylate) as polymeric support. Con A was immobilized on Cu(II)-charged iminodiacetic acid (IDA) regenerable sorbents by forming a IDA:Cu(II):Con A sandwich affinity structure that has high column capacity as well as stability. When compared with conventional Con A lectin chromatography, the monolithic capillary enabled the better reproducible detection of over double the number of unique N-glycoproteins in human urine samples. Utility for analysis of minimal biological samples was confirmed by the successful elucidation of glycoprotein profiles in mouse urine samples at the microliter scale. The improved efficiency of the nano-scale monolithic capillary will impact the analysis of glycoproteins in complex biological samples, especially where only limited material may be available. PMID:19366252

Assay for the simultaneous determination of guanidinoacetic acid, creatinine and creatine in plasma and urine by capillary electrophoresis UV-detection.

PubMed

Zinellu, Angelo; Sotgia, Salvatore; Zinellu, Elisabetta; Chessa, Roberto; Deiana, Luca; Carru, Ciriaco

2006-03-01

Guanidinoacetic acid (GAA) measurement has recently become of great interest for the diagnosis of creatine (Cn) metabolism disorders, and research calls for rapid and inexpensive methods for its detection in plasma and urine in order to assess a large number of patients. We propose a new assay for the measurement of GAA by a simple CZE UV-detection without previous sample derivatization. Plasma samples were filtered by Microcon-10 microconcentrators and directly injected into the capillary, while for urine specimens a simple water dilution before injection was needed. A baseline separation was obtained in less than 8 min using a 60.2 cm x 75 microm uncoated silica capillary, 75 mmol/L Tris-phosphate buffer pH 2.25 at 15 degrees C. The performance of the developed method was assessed by measuring plasma creatinine and Cn in 32 normal subjects and comparing the data obtained by the new method with those found with the previous CE assay. Our new method seems to be an inexpensive, fast and specific tool to assess a large number of patients both in clinical and in research laboratories.

Unloading oxygen in a capillary vessel under a pathological condition.

PubMed

Escobar, C; Méndez, F

2008-10-01

In this work, we study theoretically the unloading of oxygen from a hemoglobin molecule to the wall of a typical capillary vessel, considering that the hemoglobin under pathological conditions, obeys the rheological Maxwell model. Based on recent experimental evidences in hypertension, we consider that the red blood cells (RBCs) are composed by a single continuous medium in contrast with the classical particulate or discrete RBC models, which are only valid under normal physiological conditions. The analysis considers the hemodynamic interactions between the plasma and the hemoglobin, both circulating in a long horizontal capillary. We apply numerical and analytical methods to obtain the main fluid-dynamic characteristics for both fluids in the limit of low Reynolds and Womersley numbers. A diffusion boundary layer formulation for the oxygen transport in the combined plasma-hemoglobin core region is presented. The main aspects derived are the time and spatial evolution of the membrane. The hemoglobin and plasma velocities and the pressure distributions are shown. For the oxygen unloading the results are the oxy-hemoglobin saturation, the oxygen flux and the oxygen concentration in the cell-free plasma layer. The volume fraction of red blood cells and the Strouhal number have a great influence on the hemodynamic interactions.

Dynamic wetting failure in surfactant solutions

NASA Astrophysics Data System (ADS)

Liu, Chen-Yu; Vandre, Eric; Carvalho, Marcio; Kumar, Satish

2015-11-01

The influence of insoluble surfactants on dynamic wetting failure during displacement of Newtonian fluids in a rectangular channel is studied in this work. A hydrodynamic model for steady Stokes flows of dilute surfactant solutions is developed and evaluated using three approaches: (i) a one-dimensional (1D) lubrication-type approach, (ii) a novel hybrid of a 1D description of the receding phase and a 2D description of the advancing phase, and (iii) an asymptotic theory of Cox. Steady-state solution families in the form of macroscopic contact angles as a function of the capillary number are determined and limit points are identified. When air is the receding fluid, Marangoni stresses are found to increase the receding-phase pressure gradients near the contact line by thinning the air film without significantly changing the capillary-pressure gradients there. As consequence, the limit points shift to lower capillary numbers and the onset of wetting failure is promoted. The model predictions are then used to interpret decades-old experimental observations concerning the influence of surfactants on air entrainment. The hybrid modeling approach developed here can readily be extended to more complicated geometries where a thin air layer is present near a contact line.

Nailfold videocapillaroscopy micro-haemorrhage and giant capillary counting as an accurate approach for a steady state definition of disease activity in systemic sclerosis.

PubMed

Sambataro, Domenico; Sambataro, Gianluca; Zaccara, Eleonora; Maglione, Wanda; Polosa, Riccardo; Afeltra, Antonella M V; Vitali, Claudio; Del Papa, Nicoletta

2014-10-09

Nailfold videocapillaroscopy (NVC) in systemic sclerosis (SSc) is a procedure commonly used for patient classification and subsetting, but not to define disease activity (DA). This study aimed to evaluate whether the number of micro-haemorrhages (MHE), micro-thrombosis (MT), giant capillaries (GC), and normal/dilated capillaries (Cs) in NVC could predict DA in SSc. Eight-finger NVC was performed in 107 patients with SSc, and the total number of MHE/MT, GC, and the mean number of Cs were counted and defined as number of micro-haemorrhages (NEMO), GC and Cs scores, respectively. The European Scleroderma Study Group (ESSG) index constituted the gold standard for DA assessment, and scores ≥ 3.5 and = 3 were considered indicative of high and moderate activity, respectively. NEMO and GC scores were positively correlated with ESSG index (R = 0.65, P < 0.0001, and R = 0.47, P <0.0001, respectively), whilst Cs score showed a negative correlation with that DA index (R = -0.30, P <0.001). The area under the curve (AUC) of receiver operating characteristic plots, obtained by NEMO score sensitivity and specificity values in classifying patients with ESSG index ≥ 3.5, was significantly higher than the corresponding AUC derived from either GC or Cs scores (P <0.03 and P <0.0006, respectively). A modified score, defined by the presence of a given number of MHE/MT and GC, had a good performance in classifying active patients (ESSG index ≥ 3, sensitivity 95.1%, specificity 84.8%, accuracy 88.7%). MHE/MT and GC appear to be good indicators of DA in SSc, and enhances the role of NVC as an easy technique to identify active patients.

Rapidly moving contact lines and damping contributions

NASA Astrophysics Data System (ADS)

Xia, Yi; Daniel, Susan; Steen, Paul

2017-11-01

Contact angle varies dynamically with contact line (CL) speed when a liquid moves across a solid support, as when a liquid spreads rapidly. For sufficiently rapid spreading, inertia competes with capillarity to influence the interface shape near the support. We use resonant-mode plane-normal support oscillations of droplets to drive lateral contact-line motion. Reynolds numbers based on CL speeds are high and capillary numbers are low. These are inertial-capillary motions. By scanning the driving frequency, we locate the frequency at peak amplification (resonance), obtain the scaled peak height (amplification factor) and a measure of band-width (damping ratio). We report how a parameter for CL mobility depends on these scanning metrics, with the goal of distinguishing contributions from the bulk- and CL-dissipation to overall damping.

Preliminary application of tapered glass capillary microbeam in MeV-PIXE mapping of longan leaf for elemental concentration distribution analysis

NASA Astrophysics Data System (ADS)

Natyanun, S.; Unai, S.; Yu, L. D.; Tippawan, U.; Pussadee, N.

2017-09-01

This study was aimed at understanding elemental concentration distribution in local longan leaf for how the plant was affected by the environment or agricultural operation. The analysis applied the MeV-microbeam particle induced X-ray emission (PIXE) mapping technique using a home-developed tapered glass capillary microbeam system at Chiang Mai University. The microbeam was 2-MeV proton beam in 130 µm in diameter. The studying interest was in the difference in the elemental concentrations distributed between the leaf midrib and lamina areas. The micro proton beam analyzed the leaf sample across the leaf midrib edge to the leaf lamina area for total 9 data requisition spots. The resulting data were colored to form a 1D-map of the elemental concentration distribution. Seven dominant elements, Al, S, Cl, K, Ca, Sc and Fe, were identified, the first six of which were found having higher concentrations in the midrib area than in the lamina area, while the Fe concentration was in an opposite trend to that of the others.

Detection of Dystrophin Dp71 in Human Skeletal Muscle Using an Automated Capillary Western Assay System.

PubMed

Kawaguchi, Tatsuya; Niba, Emma Tabe Eko; Rani, Abdul Qawee Mahyoob; Onishi, Yoshiyuki; Koizumi, Makoto; Awano, Hiroyuki; Matsumoto, Masaaki; Nagai, Masashi; Yoshida, Shinobu; Sakakibara, Sachiko; Maeda, Naoyuki; Sato, Osamu; Nishio, Hisahide; Matsuo, Masafumi

2018-05-23

Dystrophin Dp71 is one of the isoforms produced by the DMD gene which is mutated in patients with Duchenne muscular dystrophy (DMD). Although Dp71 is expressed ubiquitously, it has not been detected in normal skeletal muscle. This study was performed to assess the expression of Dp71 in human skeletal muscle. Human skeletal muscle RNA and tissues were obtained commercially. Mouse skeletal muscle was obtained from normal and DMD mdx mice. Dp71 mRNA and protein were determined by reverse-transcription PCR and an automated capillary Western assay system, the Simple Western, respectively. Dp71 was over-expressed or suppressed using a plasmid expressing Dp71 or antisense oligonucleotide, respectively. Full-length Dp71 cDNA was PCR amplified as a single product from human skeletal muscle RNA. A ca. 70 kDa protein peak detected by the Simple Western was determined as Dp71 by over-expressing Dp71 in HEK293 cells, or suppressing Dp71 expression with antisense oligonucleotide in rhabdomyosarcoma cells. The Simple Western assay detected Dp71 in the skeletal muscles of both normal and DMD mice. In human skeletal muscle, Dp71 was also detected. The ratio of Dp71 to vinculin of human skeletal muscle samples varied widely, indicating various levels of Dp71 expression. Dp71 protein was detected in human skeletal muscle using a highly sensitive capillary Western blotting system.

Effects of Acanthus ebracteatus Vahl on tumor angiogenesis and on tumor growth in nude mice implanted with cervical cancer

PubMed Central

Mahasiripanth, Taksanee; Hokputsa, Sanya; Niruthisard, Somchai; Bhattarakosol, Parvapan; Patumraj, Suthiluk

2012-01-01

Purpose The aim of this study was to examine the effects of the crude extract of Acanthus ebracteatus Vahl (AE) on tumor growth and angiogenesis by utilizing a tumor model in which nude mice were implanted with cervical cancer cells containing human papillomavirus 16 DNA (HPV-16 DNA). Materials and methods The growth-inhibitory effect of AE was investigated in four different cell types: CaSki (HPV-16 positive), HeLa (HPV-18 positive), hepatocellular carcinoma cells (HepG2), and human dermal fibroblast cells (HDFs). The cell viabilities and IC50 values of AE were determined in cells incubated with AE for different lengths of time. To conduct studies in vivo, female BALB/c nude mice (aged 6–7 weeks, weighing 20–25 g) were used. A cervical cancer-derived cell line (CaSki) with integrated HPV-16 DNA was injected subcutaneously (1 × 107 cells/200 μL) in the middle dorsum of each animal (HPV group). One week after injection, mice were fed orally with AE crude extract at either 300 or 3000 mg/kg body weight/day for 14 or 28 days (HPV-AE groups). Tumor microvasculature and capillary vascularity were determined using laser scanning confocal microscopy. Tumor tissue was collected from each mouse to evaluate tumor histology and vascular endothelial growth factor (VEGF) immunostaining. Results The time-response curves of AE and the dose-dependent effect of AE on growth inhibition were determined. After a 48-hour incubation period, the IC50 of AE in CaSki was discovered to be significantly different from that of HDFs (P < 0.05). A microvascular network was observed around the tumor area in the HPV group on days 21 and 35. Tumor capillary vascularity in the HPV group was significantly increased compared with the control group (P < 0.001). High-dose treatment of AE extract (HPV-3000AE group) significantly attenuated the increase in VEGF expression and tumor angiogenesis in mice that received either the 14- or 28-day treatment period (P < 0.001). Conclusion Our novel findings demonstrated that AE crude extract could inhibit cervical cancer growth, VEGF expression, and angiogenesis in a CaSki-cell transplant model in mice. PMID:22977311

Does stinging nettle (Urtica dioica) have an effect on bone formation in the expanded inter-premaxillary suture?

PubMed

Irgin, Celal; Çörekçi, Bayram; Ozan, Fatih; Halicioğlu, Koray; Toptaş, Orçun; Birinci Yildirim, Arzu; Türker, Arzu; Yilmaz, Fahri

2016-09-01

To determine whether systemically given stinging nettle (SN) has an effect on bone formation in response to expansion of the rat inter-premaxillary suture. A total of 28 male Wistar albino rats were randomly divided into 4 equal groups: control (C), only expansion (OE), SN extract given only during the expansion and retention periods (SN group; a total of 17days), and SN extract given during the nursery phase before expansion (a period of 40days) and during the expansion and retention periods (N+SN group; a total of 57days). After the 5-day expansion period was completed, the rats in the OE, SN, and N+SN groups underwent 12days of mechanical retention, after which they were sacrificed, and their premaxilla were dissected and fixed. A histologic evaluation was done to determine the number of osteoblasts, osteoclasts, and capillaries, as well as the number and intensity of inflammatory cells and new bone formation. Statistically significant differences were found between the groups in all histologic parameters except the ratio of intensities of inflammatory cells. New bone formation and the number of capillaries were significantly higher in the SN groups than in the other groups. The statistical analysis also showed that the numbers of osteoblasts, osteoclasts, and capillaries were highest in the N+SN group. Systemic administration of SN may be effective in accelerating new bone formation and reducing inflammation in the maxillary expansion procedure. It may also be beneficial in preventing relapse after the expansion procedure. Copyright © 2016 Elsevier Ltd. All rights reserved.

Serological cross-reactivity among Sporothrix schenckii, Ceratocystis, Europhium, and Graphium species.

PubMed Central

Ishizaki, H; Wheat, R W; Kiel, D P; Conant, N F

1978-01-01

Ethanol-precipitable culture filtrate antigens of 100 strains of 75 species of the Sporothrix-Ceratocystis-Europhium-Graphium complex and 1 species of Botrytis were examined for neutral sugar components and for serological cross-reactivity with S. schenckii rabbit antiserum and human sporotrichosis sera by capillary precipitin and double immunodiffusion assay. Results revealed that cross-reactive species (60 of 77, ca. 80%) produced exoconidial forms and rhamnose- and mannose-containing polysaccharides and included Ceratocystis, the three known Europhium, and several Graphium-form species. Endoconidial-form Ceratocystis species did not cross-react. Images PMID:99369

Lennard-Jones fluids in two-dimensional nano-pores. Multi-phase coexistence and fluid structure

NASA Astrophysics Data System (ADS)

Yatsyshin, Petr; Savva, Nikos; Kalliadasis, Serafim

2014-03-01

We present a number of fundamental findings on the wetting behaviour of nano-pores. A popular model for fluid confinement is a one-dimensional (1D) slit pore formed by two parallel planar walls and it exhibits capillary condensation (CC): a first-order phase transition from vapour to capillary-liquid (Kelvin shift). Capping such a pore at one end by a third orthogonal wall forms a prototypical two-dimensional (2D) pore. We show that 2D pores possess a wetting temperature such that below this temperature CC remains of first order, above it becomes a continuous phase transition manifested by a slab of capillary-liquid filling the pore from the capping wall. Continuous CC exhibits hysteresis and can be preceded by a first-order capillary prewetting transition. Additionally, liquid drops can form in the corners of the 2D pore (remnant of 2D wedge prewetting). The three fluid phases, vapour, capillary-liquid slab and corner drops, can coexist at the pore triple point. Our model is based on the statistical mechanics of fluids in the density functional formulation. The fluid-fluid and fluid-substrate interactions are dispersive. We analyze in detail the microscopic fluid structure, isotherms and full phase diagrams. Our findings also suggest novel ways to control wetting of nano-pores. We are grateful to the European Research Council via Advanced Grant No. 247031 for support.

Influence of local capillary trapping on containment system effectiveness

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bryant, Steven

2014-03-31

Immobilization of CO 2 injected into deep subsurface storage reservoirs is a critical component of risk assessment for geologic CO 2 storage (GCS). Local capillary trapping (LCT) is a recently established mode of immobilization that arises when CO 2 migrates due to buoyancy through heterogeneous storage reservoirs. This project sought to assess the amount and extent of LCT expected in storage formations under a range of injection conditions, and to confirm the persistence of LCT if the seal overlying the reservoir were to lose its integrity. Numerical simulation using commercial reservoir simulation software was conducted to assess the influence ofmore » injection. Laboratory experiments, modeling and numerical simulation were conducted to assess the effect of compromised seal integrity. Bench-scale (0.6 m by 0.6 m by 0.03 m) experiments with surrogate fluids provided the first empirical confirmation of the key concepts underlying LCT: accumulation of buoyant nonwetting phase at above residual saturations beneath capillary barriers in a variety of structures, which remains immobile under normal capillary pressure gradients. Immobilization of above-residual saturations is a critical distinction between LCT and the more familiar “residual saturation trapping.” To estimate the possible extent of LCT in a storage reservoir an algorithm was developed to identify all potential local traps, given the spatial distribution of capillary entry pressure in the reservoir. The algorithm assumes that the driving force for CO 2 migration can be represented as a single value of “critical capillary entry pressure” P c,entry crit, such that cells with capillary entry pressure greater/less than P c,entry crit act as barriers/potential traps during CO 2 migration. At intermediate values of P c,entry crit, the barrier regions become more laterally extensive in the reservoir, approaching a percolation threshold while non-barrier regions remain numerous. The maximum possible extent of LCT thus occurs at P c,entry crit near this threshold. Testing predictions of this simple algorithm against full-physics simulations of buoyancy-driven CO 2 migration support the concept of critical capillary entry pressure. However, further research is needed to determine whether a single value of critical capillary entry pressure always applies and how that value can be determined a priori. Simulations of injection into high-resolution (cells 0.3 m on a side) 2D and 3D heterogeneous domains show two characteristic behaviors. At small gravity numbers (vertical flow velocity much less than horizontal flow velocity) the CO 2 fills local traps as well as regions that would act as local barriers if CO 2 were moving only due to buoyancy. When injection ceases, the CO 2 migrates vertically to establish large saturations within local traps and residual saturation elsewhere. At large gravity numbers, the CO 2 invades a smaller portion of the perforated interval. Within this smaller swept zone the local barriers are not invaded, but local traps are filled to large saturation during injection and remain during post-injection gravity-driven migration. The small gravity number behavior is expected in the region within 100 m of a vertical injection well at anticipated rates of injection for commercial GCS. Simulations of leakage scenarios (through-going region of large permeability imposed in overlying seal) indicate that LCT persists (i.e. CO 2 remains held in a large fraction of the local iv traps) and the persistence is independent of injection rate during storage. Simulations of leakage for the limiting case of CO 2 migrating vertically from an areally extensive emplacement in the lower portion of a reservoir showed similar strong persistence of LCT. This research has two broad implications for GCS. The first is that LCT can retain a significant fraction of the CO 2 stored in a reservoir – above and beyond the residual saturation -- if the overlying seal were to fail. Thus frameworks for risk assessment should be extended to account for LCT. The second implication is that compared to pressure driven flow in reservoirs, CO 2 migration and trapping behave in a qualitatively different manner in heterogeneous reservoirs when buoyancy is the dominant driving force for flow. Thus simulations of GCS that neglect capillary heterogeneity will fail to capture important features of the CO 2 plume. While commercial reservoir simulation software can account for fine scale capillary heterogeneity, it has not been designed to work efficiently with such domains, and no simulators can handle fine-scale resolution throughout the reservoir. A possible way to upscale the migration and trapping is to apply an “effective residual saturation” to coarse-scale grids. While the extent of overall immobilization can be correlated in this way, all coarser grids failed to capture the distance traveled by the migrating CO 2 for large gravity number. Thus it remains unclear how best to account for LCT in the routine simulation work-flow that will be needed for large-scale GCS. Alternatives meriting investigation include streamline methods, reduced-physics proxies (e.g. particle tracking), and biased invasion percolation algorithms, which are based on precisely the capillary heterogeneity essential for LCT.« less

Local Membrane Deformations Activate Ca2+-Dependent K+ and Anionic Currents in Intact Human Red Blood Cells

PubMed Central

Dyrda, Agnieszka; Cytlak, Urszula; Ciuraszkiewicz, Anna; Lipinska, Agnieszka; Cueff, Anne; Bouyer, Guillaume; Egée, Stéphane; Bennekou, Poul; Lew, Virgilio L.; Thomas, Serge L. Y.

2010-01-01

Background The mechanical, rheological and shape properties of red blood cells are determined by their cortical cytoskeleton, evolutionarily optimized to provide the dynamic deformability required for flow through capillaries much narrower than the cell's diameter. The shear stress induced by such flow, as well as the local membrane deformations generated in certain pathological conditions, such as sickle cell anemia, have been shown to increase membrane permeability, based largely on experimentation with red cell suspensions. We attempted here the first measurements of membrane currents activated by a local and controlled membrane deformation in single red blood cells under on-cell patch clamp to define the nature of the stretch-activated currents. Methodology/Principal Findings The cell-attached configuration of the patch-clamp technique was used to allow recordings of single channel activity in intact red blood cells. Gigaohm seal formation was obtained with and without membrane deformation. Deformation was induced by the application of a negative pressure pulse of 10 mmHg for less than 5 s. Currents were only detected when the membrane was seen domed under negative pressure within the patch-pipette. K+ and Cl− currents were strictly dependent on the presence of Ca2+. The Ca2+-dependent currents were transient, with typical decay half-times of about 5–10 min, suggesting the spontaneous inactivation of a stretch-activated Ca2+ permeability (PCa). These results indicate that local membrane deformations can transiently activate a Ca2+ permeability pathway leading to increased [Ca2+]i, secondary activation of Ca2+-sensitive K+ channels (Gardos channel, IK1, KCa3.1), and hyperpolarization-induced anion currents. Conclusions/Significance The stretch-activated transient PCa observed here under local membrane deformation is a likely contributor to the Ca2+-mediated effects observed during the normal aging process of red blood cells, and to the increased Ca2+ content of red cells in certain hereditary anemias such as thalassemia and sickle cell anemia. PMID:20195477

Local membrane deformations activate Ca2+-dependent K+ and anionic currents in intact human red blood cells.

PubMed

Dyrda, Agnieszka; Cytlak, Urszula; Ciuraszkiewicz, Anna; Lipinska, Agnieszka; Cueff, Anne; Bouyer, Guillaume; Egée, Stéphane; Bennekou, Poul; Lew, Virgilio L; Thomas, Serge L Y

2010-02-26

The mechanical, rheological and shape properties of red blood cells are determined by their cortical cytoskeleton, evolutionarily optimized to provide the dynamic deformability required for flow through capillaries much narrower than the cell's diameter. The shear stress induced by such flow, as well as the local membrane deformations generated in certain pathological conditions, such as sickle cell anemia, have been shown to increase membrane permeability, based largely on experimentation with red cell suspensions. We attempted here the first measurements of membrane currents activated by a local and controlled membrane deformation in single red blood cells under on-cell patch clamp to define the nature of the stretch-activated currents. The cell-attached configuration of the patch-clamp technique was used to allow recordings of single channel activity in intact red blood cells. Gigaohm seal formation was obtained with and without membrane deformation. Deformation was induced by the application of a negative pressure pulse of 10 mmHg for less than 5 s. Currents were only detected when the membrane was seen domed under negative pressure within the patch-pipette. K(+) and Cl(-) currents were strictly dependent on the presence of Ca(2+). The Ca(2+)-dependent currents were transient, with typical decay half-times of about 5-10 min, suggesting the spontaneous inactivation of a stretch-activated Ca(2+) permeability (PCa). These results indicate that local membrane deformations can transiently activate a Ca(2+) permeability pathway leading to increased [Ca(2+)](i), secondary activation of Ca(2+)-sensitive K(+) channels (Gardos channel, IK1, KCa3.1), and hyperpolarization-induced anion currents. The stretch-activated transient PCa observed here under local membrane deformation is a likely contributor to the Ca(2+)-mediated effects observed during the normal aging process of red blood cells, and to the increased Ca(2+) content of red cells in certain hereditary anemias such as thalassemia and sickle cell anemia.

Carbonation acceleration of calcium hydroxide nanoparticles: induced by yeast fermentation

NASA Astrophysics Data System (ADS)

Lopez-Arce, Paula; Zornoza-Indart, Ainara

2015-09-01

Carbonation of Ca(OH)2 nanoparticles and consolidation of limestone are accelerated by high humidity and a yeast fermentation system that supplies a saturated atmosphere on CO2, H2O vapor and ethanol during 28 days. Nanoparticles were analyzed by X-ray diffraction and differential thermal analyses with thermogravimetry. Spectrophotometry, scanning electron microscopy analyses, and hydric and mechanical tests were also performed in stones specimens. Samples exposed to the yeast environment achieve 100 % relative CaCO3 yield, whereas at high humidity but without the yeast and under laboratory environment, relative yields of 95 % CaCO3 and 15 % CaCO3 are, respectively, reached, with white crusts and glazing left on the stone surfaces when the nanoparticles are applied at a concentration of 25 g/l. The largest increase in the drilling resistance and surface hardness values with slight increase in the capillarity absorption and desorption coefficients and with lesser stone color changes are produced at a concentration of 5 g/l, in the yeast system environment. This especially happens in stone specimens initially with bimodal pore size distributions, more amounts of pores with diameters between 0.1 and 1 µm, higher open porosity values and faster capillary coefficients. An inexpensive and reliable method based on water and yeast-sugar solution is presented to speed up carbonation of Ca(OH)2 nanoparticles used as a consolidating product to improve the mechanical properties of decayed limestone from archaeological and architectural heritage.

Experiments versus modeling of buoyant drying of porous media

NASA Astrophysics Data System (ADS)

Salin, D.; Yiotis, A.; Tajer, E.; Yortsos, Y. C.

2012-12-01

Experiments versus modeling of buoyant drying of porous media D. Salin and A.G. Yiotis, Laboratoire FAST, Univ Pierre & Marie Curie, Univ. Paris-Sud, CNRS, Orsay 91405, France and E.S. Tajer and Y.C. Yortsos, Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-1450 A series of isothermal drying experiments in packed glass beads saturated with volatile hydrocarbons (hexane or pentane) are conducted. The transparent glass cells containing the packing allow for the visual monitoring of the phase distribution patterns below the surface, including the formation of liquid films, as the gaseous phase invades the pore space, and for the control of the thickness of the diffusive mass boundary layer over the packing. We demonstrate the existence of an early Constant Rate Period, CRP, that lasts as long as the films saturate the surface of the packing, and of a subsequent Falling Rate Period, FRP, that begins practically after the detachment of the film tips from the external surface. During the CRP, the process is controlled by diffusion within the stagnant gaseous phase in the upper part of the cells, yielding a Stefan tube problem solution. During the FRP, the process is controlled by diffusion within the packing, with a drying rate inversely proportional to the observed position of the film tips in the cell. The critical residual liquid saturation that marks the transition between these two regimes is found to be a function of the average bead size in our packs and the incline of the cells with respect to the flat vertical, with larger beads and angles closer to the vertical position leading to earlier film detachment times and higher critical saturations. We developed a model for the drying of porous media in the presence of gravity. It incorporated effects of corner film flow, internal and external mass transfer and the effect of gravity. Analytical results were derived when gravity opposes drying and hence leads to a stable percolation drying front. We are thus able to obtain results for the drying rates, the critical saturation and the extent of the film region with respect to the various dimensionless numbers that describe the process; the Bond (Bo)number, a film-based Capillary (Ca) number and the dimensionless extent of the mass boundary layer (Sh). The experimental results agree very well with the theory, provided that the latter is generalized to account for the effects of corner roundness in the film region which were neglected in our analytical approach. The agreement is achieved for a specific value of the roundness of the films, which is found to be constant and equal to 0.2 for various conditions, and verify the theoretical dependence on Ca, Bo and Sh numbers.

Separation of organic cations using novel background electrolytes by capillary electrophoresis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steiner, S.; Fritz, J.

2008-02-12

A background electrolyte for capillary electrophoresis containing tris(-hydroxymethyl) aminomethane (THAM) and ethanesulfonic acid (ESA) gives excellent efficiency for separation of drug cations with actual theoretical plate numbers as high as 300,000. However, the analyte cations often elute too quickly and consequently offer only a narrow window for separation. The best way to correct this is to induce a reverse electroosmotic flow (EOF) that will spread out the peaks by slowing their migration rates, but this has always been difficult to accomplish in a controlled manner. A new method for producing a variable EOF is described in which a low variablemore » concentration of tributylammonium- or triethylammonium ESA is added to the BGE. The additive equilibrates with the capillary wall to give it a positive charge and thereby produce a controlled opposing EOF. Excellent separations of complex drug mixtures were obtained by this method.« less

RP-1 and JP-8 Thermal Stability Experiments

NASA Technical Reports Server (NTRS)

Brown, Sarah P.; Emens, Jessica M.; Frederick, Robert A., Jr.

2005-01-01

This work experimentally investigates the effect of fuel composition changes on jet and rocket fuel thermal stability. A High Reynolds Number Thermal Stability test device evaluated JP-8 and RP-1 fuels. The experiment consisted of an electrically heated, stainless steel capillary tube with a controlled fuel outlet temperature. An optical pyrometer monitored the increasing external temperature profiles of the capillary tube as deposits build inside during each test. Multiple runs of each fuel composition provided results on measurement repeatability. Testing a t two different facilities provided data on measurement reproducibility. The technique is able to distinguish between thermally stable and unstable compositions of JP-8 and intermediate blends made by combining each composition. The technique is also able to distinguish among standard RP-1 rocket fuels and those having reduced sulfur levels. Carbon burn off analysis of residue in the capillary tubes on the RP-1 fuels correlates with the external temperature results.

[Characteristics of electroosmotic flow in open-tubular capillary electrochromatography with magnetic nanoparticle coating as mixed-mode stationary phase].

PubMed

Qin, Sasa; Zhou, Chaoran; Zhu, Yaxian; Ren, Zhiyu; Zhang, Lingyi; Fu, Honggang; Zhang, Weibing

2011-09-01

A novel open-tubular capillary electrochromatography (OT-CEC) column with magnetic nanoparticle coating as mixed-mode stationary phase was prepared. The mixed-mode stationary phases were obtained by mixing C18 and amino modified magnetic nanoparticles with different ratios. The mixed modified magnetic nanoparticles as stationary phase were introduced into the capillary by using external magnetic force. The magnetic nanoparticle coating can be easily regenerated by removing the external magnetic field, and applied to other separation modes. The characteristics of electroosmotic flow (EOF) were theoretically investigated through the effect of physicochemical properties of different stationary phases on EOF. The experiment was conducted under different ratios of mixed-mode stationary phases and coating lengths, and it was verified that the theoretical conclusions accorded with the experimental results. It was shown that the EOF can be easily adjusted by changing the ratio of stationary phases or the number of permanent magnets.

Improved DESI-MS Performance using Edge Sampling and aRotational Sample Stage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kertesz, Vilmos; Van Berkel, Gary J

2008-01-01

The position of the surface to be analyzed relative to the sampling orifice or capillary into the mass spectrometer has been known to dramatically affect the observed signal levels in desorption electrospray ionization mass spectrometry (DESIMS). In analyses of sample spots on planar surfaces, DESI-MS signal intensities as much as five times greater were routinely observed when the bottom of the sampling capillary was appropriately positioned beneath the surface plane ( edge sampling") compared to when the capillary just touched the surface. To take advantage of the optimum "edge sampling" geometry and to maximize the number of samples that couldmore » be analyzed in this configuration, a rotational sample stage was integrated into a typical DESI-MS setup. The rapid quantitative determination of caffeine in two diet sport drinks (Diet Turbo Tea, Speed Stack Grape) spiked with an isotopically labeled internal standard demonstrated the utility of this approach.« less

Light-induced cross transport phenomena in a single-component gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chermyaninov, I. V.; Chernyak, V. G., E-mail: Vladimir.Chernyak@usu.ru

2013-07-15

The cross transport processes that occur in a single-component gas in a capillary and are caused by resonance laser radiation and pressure and temperature gradients are studied. An expression for entropy production is derived using a system of kinetic Boltzmann equations in a linear approximation. The kinetic coefficients that determine the transport processes are shown to satisfy the Onsager reciprocal relations at any Knudsen numbers and any character of the elastic interaction of gas particles with the capillary surface. The light-induced baro- and thermoeffects that take place in a closed heat-insulated system in the field of resonance laser radiation aremore » considered. Analytical expressions are obtained for the Onsager coefficients in an almost free-molecular regime. The light-induced pressure and temperature gradients that appear in a closed heat-insulated capillary under typical experimental conditions are numerically estimated.« less

Effect of Royal Jelly on new bone formation in rapid maxillary expansion in rats.

PubMed

Özan, Fatih; Çörekçi, Bayram; Toptaş, Orçun; Halicioğlu, Koray; Irgin, Celal; Yilmaz, Fahri; Hezenci, Yasin

2015-11-01

The aim of this study was to evaluate the effects of long and short term systemic usage of royal jelly on bone formation in the expanded maxillary suture in a rat model. Twenty eight Wistar albino rats were randomly divided into 4 equal groups: Control (C); Only Expansion (OE), Royal Jelly (RJ) group, Royal Jelly was given to rats by oral gavage only during the expansion and retention period; Royal Jelly plus Nursery (RJN) group, Royal Jelly was given to rats by oral gavage during their nursery phase of 40 days and during the retention period. After the 5 day expansion period was completed, the rats underwent 12 days of mechanical retention. All rats were sacrificed in same time. Histological examination was performed to determine the number of osteoclasts, number of osteoblasts, number of capillaries, inflammatory cell infiltration, and new bone formation. New bone formation, number of osteoclasts, number of osteoblasts, and the number of capillaries in the expanded maxillary sutures were higher in the RJ and RJN groups than in the other groups. Statistical analysis also demonstrated that new bone formation and the number of osteoblasts was also highest in the RJN group. The systemic administration of Royal Jelly in conjunction with rapid maxillary expansion may increase the quality of regenerated bone.

Ultrastructural response of rat lung to 90 days' exposure to oxygen at 450 mm Hg

NASA Technical Reports Server (NTRS)

Harrison, G. A.

1974-01-01

Young Sprague-Dawley rats were exposed to 100% oxygen at 450 mm Hg in constant environment capsules for 90 days. Lung tissue examined by electron microscopy revealed a number of changes, many similar to those observed after exposure to oxygen at 760 mm Hg for shorter periods of time. Alterations in vesicle size and number and in mitochondrial matrix and cristae appear in both the endothelial and epithelial cells. Blebbing and rarefication of cytoplasm occur in both cell layers of the alveolo-capillary wall. Also seen are fluid in the basement membrane, platelets in the capillaries, and alveolar fluid and debris. All of these alterations occur at 1 atm exposure. However, after exposure to 450 mm Hg the changes are not as widespread nor as destructive as they are at the higher pressure.

Biochemical process of ureolysis-based microbial CaCO3 precipitation and its application in self-healing concrete.

PubMed

Xu, Jing; Wang, Xianzhi; Wang, Binbin

2018-04-01

Urea hydrolysis has already been considered as the most effective pathway for microbially induced CaCO 3 precipitation (MICP). The present work first studied the combination of several key factors including initial pH, temperature, and dosage of urea, which contribute to the biochemical process of MICP. Under an amiable condition of pH and temperature, the dosage of urea has a significant impact on the rate of urea degradation and CaCO 3 precipitation. A bacteria-based self-healing system was developed by loading healing agents on ceramsite carriers. The self-healing efficiency was evaluated by visual inspection on crack closure, compressive strength regain, and capillary water absorption. A preferable healing effectiveness was obtained when the bacteria and organic nutrients were co-immobilized in carriers. Image analysis showed that cracks up to 273 μm could be healed with a crack closure ratio of 86% in 28 days. The compressive strength regain increased 24% and the water absorption coefficient decreased 27% compared to the reference. The findings indicated a promising application of ureolysis-based MICP in restoring the mechanical properties and enhancing the durability of concrete.

Skeletal muscle satellite cells are located at a closer proximity to capillaries in healthy young compared with older men.

PubMed

Nederveen, Joshua P; Joanisse, Sophie; Snijders, Tim; Ivankovic, Victoria; Baker, Steven K; Phillips, Stuart M; Parise, Gianni

2016-12-01

Skeletal muscle satellite cells (SC) are instrumental in maintenance of muscle fibres, the adaptive responses to exercise, and there is an age-related decline in SC. A spatial relationship exists between SC and muscle fibre capillaries. In the present study, we aimed to investigate whether chronologic age has an impact on the spatial relationship between SC and muscle fibre capillaries. Secondly, we determined whether this spatial relationship changes in response to a single session of resistance exercise. Muscle biopsies were obtained from the vastus lateralis of previously untrained young men (YM, 24 ± 3 years; n  = 23) and older men (OM, 67 ± 4 years; n  = 22) at rest. A subset of YM ( n  = 9) performed a single bout of resistance exercise, where additional muscle biopsies taken at 24 and 72 h post-exercise recovery. Skeletal muscle fibre capillarization, SC content, and activation status were assessed using immunofluorescent microscopy of muscle cross sections. Type II muscle fibre SC and capillary content was significantly lower in the YM compared with OM ( P  < 0.05). Furthermore, type II muscle fibre SC were located at a greater distance from the nearest capillary in OM compared with YM (21.6 ± 1.3 vs. 17.0 ± 0.8 µm, respectively; P  < 0.05). In response to a single bout of exercise, we observed a significant increase in SC number and activation status ( P  < 0.05). In addition, activated vs. quiescent SC were situated closer ( P  < 0.05) to capillaries. We demonstrate that there is a greater distance between capillaries and type II fibre-associated SC in OM as compared with YM. Furthermore, quiescent SC are located significantly further away from capillaries than active SC after single bout of exercise. Our data have implications for how muscle adapts to exercise and how aging may affect such adaptations.

Effect of an insoluble surfactant on the dynamics of a thin liquid film flowing over a non-uniformly heated substrate.

PubMed

Srivastava, Ashna; Tiwari, Naveen

2018-05-07

The stability analysis of a gravity-driven thin liquid film with an insoluble surfactant flowing over a surface with embedded, regularly spaced heaters is investigated. At the leading edge of a heater, the presence of a temperature gradient induces an opposing Marangoni stress at the interface leading to the formation of a capillary ridge. This ridge has been shown to be susceptible to thermocapillary (oscillating in the flow direction) and rivulet (spanwise periodic pattern) instabilities. The presence of an insoluble surfactant is shown to have a stabilizing effect on this system. The governing equations for the evolution of the film thickness and surfactant concentration are obtained within the lubrication approximation. The coupled two-dimensional base solutions for the film thickness and surfactant concentration show that there is no significant change in the height of the capillary ridge at the subsequent heaters downstream. The height of the capillary ridge is reduced by the presence of the surfactant. For very small Peclet number, the presence of multiple heaters has almost no significant effect on the film stability as compared to a single heater and similar trends are observed between the two configurations in the presence of the surfactant as for the case of a clean interface. However, for large Peclet number, the effect was observed on both types of instabilities for certain heater configurations. The Biot number is shown to have a strong effect on the stability results wherein the dominant mode of instability is altered (from rivulet to thermocapillary instability) for a passive or no surfactant case with increase in the Biot number. For an active surfactant thermocapillary instability is found to remain the dominant mode of instability for all the values of the Biot number. It is shown that increasing the number of heaters beyond a couple does not further affect the stability results.

Double emulsion formation through hierarchical flow-focusing microchannel

NASA Astrophysics Data System (ADS)

Azarmanesh, Milad; Farhadi, Mousa; Azizian, Pooya

2016-03-01

A microfluidic device is presented for creating double emulsions, controlling their sizes and also manipulating encapsulation processes. As a result of three immiscible liquids' interaction using dripping instability, double emulsions can be produced elegantly. Effects of dimensionless numbers are investigated which are Weber number of the inner phase (Wein), Capillary number of the inner droplet (Cain), and Capillary number of the outer droplet (Caout). They affect the formation process, inner and outer droplet size, and separation frequency. Direct numerical simulation of governing equations was done using volume of fluid method and adaptive mesh refinement technique. Two kinds of double emulsion formation, the two-step and the one-step, were simulated in which the thickness of the sheath of double emulsions can be adjusted. Altering each dimensionless number will change detachment location, outer droplet size and droplet formation period. Moreover, the decussate regime of the double-emulsion/empty-droplet is observed in low Wein. This phenomenon can be obtained by adjusting the Wein in which the maximum size of the sheath is discovered. Also, the results show that Cain has significant influence on the outer droplet size in the two-step process, while Caout affects the sheath in the one-step formation considerably.

Deformation of ferrofluid marbles in the presence of a permanent magnet.

PubMed

Nguyen, Nam-Trung

2013-11-12

This paper investigates the deformation of ferrofluid marbles in the presence of a permanent magnet. Ferrofluid marbles are formed using a water-based ferrofluid and 1 μm hydrophobic polytetrafluoride particles. A marble placed on a Teflon coated glass plate deforms under gravity. In the presence of a permanent magnet, the marble is further deformed with a larger contact area. The geometric parameters are normalized by the radius of an undistorted spherical marble. The paper first discusses a scaling relationship between the dimensionless radius of the contact area as well as the dimensionless height and the magnetic Bond number. The dimensionless contact radius is proportional to the fourth root of the magnetic bond number. The dimensionless height scales with the inverse square root of the magnetic Bond number. In the case of a moving marble dragged by a permanent magnet, the deformation is evaluated as the difference between advancing and receding curvatures of the top view. The dimensionless height and the contact diameter of the marble do not significantly depend on the speed or the capillary number. The scaling analysis and experimental data show that the deformation is proportional to the capillary number.

Effect of capillary forces on the nonstationary fall of a drop in an infinite fluid

NASA Astrophysics Data System (ADS)

Antanovskii, L. K.

1991-12-01

An explicit solution is presented for the linear problem concerning the motion of a drop in an infinite fluid in the presence of any number of surfactants (chemical reactions are not considered in the first approximation). It is shown that the behavior of the system considered is consistent with the Le Chatelier principle. The reactivity of the capillary forces is directly related to the fundamental principles of thermodynamics, which makes it possible to write equations of surfactant thermodiffusion in symmetric form and obtain a relatively simple solution to the linearized problem.

Enantioselective determination by capillary electrophoresis with cyclodextrins as chiral selectors.

PubMed

Fanali, S

2000-04-14

This review surveys the separation of enantiomers by capillary electrophoresis using cyclodextrins as chiral selector. Cyclodextrins or their derivatives have been widely employed for the direct chiral resolution of a wide number of enantiomers, mainly of pharmaceutical interest, selected examples are reported in the tables. For method optimisation, several parameters influencing the enantioresolution, e.g., cyclodextrin type and concentration, buffer pH and composition, presence of organic solvents or complexing additives in the buffer were considered and discussed. Finally, selected applications to real samples such as pharmaceutical formulations, biological and medical samples are also discussed.

Multiphase Flow Characteristics of Heterogeneous Rocks From CO2 Storage Reservoirs in the United Kingdom

NASA Astrophysics Data System (ADS)

Reynolds, Catriona A.; Blunt, Martin J.; Krevor, Samuel

2018-02-01

We have studied the impact of heterogeneity on relative permeability and residual trapping for rock samples from the Bunter sandstone of the UK Southern North Sea, the Ormskirk sandstone of the East Irish Sea, and the Captain sandstone of the UK Northern North Sea. Reservoir condition CO2-brine relative permeability measurements were made while systematically varying the ratio of viscous to capillary flow potential, across a range of flow rates, fractional flow, and during drainage and imbibition displacement. This variation resulted in observations obtained across a range of core-scale capillary number 0.2

Pressure-viscosity measurements for several lubricants to 5.5 x 10 to the 8th power Newtons per square meter (8 x 10 to the 4th psi) and 149 C (300 F)

NASA Technical Reports Server (NTRS)

Jones, W. R.; Johnson, R. L.; Winer, W. O.; Sanborn, D. M.

1974-01-01

A capillary viscometer was used to measure viscosity as a function of pressure, temperature, and shear stress for a number of lubricants. The conditions under which the measurements were made are specified. The results obtained for each material are analyzed. It was determined that all pressure-viscosity coefficients decreased with increasing temperature. Data from other techniques such as optical elastohydrodynamics, oscillating crystal, and low shear capillary viscometry were compared with the results obtained.

Configurable Cellular Automata for Pseudorandom Number Generation

NASA Astrophysics Data System (ADS)

Quieta, Marie Therese; Guan, Sheng-Uei

This paper proposes a generalized structure of cellular automata (CA) — the configurable cellular automata (CoCA). With selected properties from programmable CA (PCA) and controllable CA (CCA), a new approach to cellular automata is developed. In CoCA, the cells are dynamically reconfigured at run-time via a control CA. Reconfiguration of a cell simply means varying the properties of that cell with time. Some examples of properties to be reconfigured are rule selection, boundary condition, and radius. While the objective of this paper is to propose CoCA as a new CA method, the main focus is to design a CoCA that can function as a good pseudorandom number generator (PRNG). As a PRNG, CoCA can be a suitable candidate as it can pass 17 out of 18 Diehard tests with 31 cells. CoCA PRNG's performance based on Diehard test is considered superior over other CA PRNG works. Moreover, CoCA opens new rooms for research not only in the field of random number generation, but in modeling complex systems as well.

Drop Tower Experiments concerning Fluid Management under Microgravity

NASA Astrophysics Data System (ADS)

Gaulke, Diana; Dreyer, Michael

2012-07-01

Transport and positioning of liquid under microgravity is done utilizing capillary forces. Therefore, capillary transport processes have to be understood for a wide variety of space applications, ranging from propellant management in tanks of space transportation systems to eating and drinking devices for astronauts. There are two types of liquid transportation in microgravity using capillary forces. First, the driven liquid flow in open channels where the capillary forces at free surfaces ensure a gas and vapor free flow. Here it is important to know the limiting flow rate through such an open channel before the free surface collapses and gas is sucked into the channel. A number of different experiments at the drop tower Bremen, on sounding rockets and at the ISS have been conducted to analyse this phenomenon within different geometries. As result a geometry dependent theory for calculating the maximum flow rate has been found. On the other hand liquid positioning and transportation requires the capillary pressure of curved surfaces to achieve a liquid flow to a desired area. Especially for space applications the weight of structure has to be taken into account for development. For example liquid positioning in tanks can be achieved via a complicated set of structure filling the whole tank resulting in heavy devices not reasonable in space applications. Astrium developed in cooperation with ZARM a propellant management device much smaller than the tank volume and ensuring a gas and vapour free supply of propellant to the propulsion system. In the drop tower Bremen a model of this device was tested concerning different microgravity scenarios. To further decrease weight and ensure functionality within different scenarios structure elements are designed as perforated geometries. Capillary transport between perforated plates has been analyzed concerning the influence of geometrical pattern of perforations. The conducted experiments at the drop tower Bremen show the remarkable influence of perforations on the capillary transport capability.

Direct Numerical Simulations of Dynamic Drainage and Imbibition to Investigate Capillary Pressure-Saturation-Interfacial Area Relation

NASA Astrophysics Data System (ADS)

Konangi, S.; Palakurthi, N. K.; Karadimitriou, N.; Comer, K.; Ghia, U.

2017-12-01

We present results of pore-scale direct numerical simulations (DNS) of drainage and imbibition in a quasi-two-dimensional (40µm thickness) porous medium with a randomly distributed packing of cylindrical obstructions. The Navier-Stokes (NS) equations are solved in the pore space on an Eulerian mesh using the open-source finite-volume computational fluid dynamics (CFD) code, OpenFOAM. The Volume-of-Fluid (VOF) method is employed to track the evolution of the fluid-fluid interface; a static contact angle is used to account for wall adhesion. From the DNS data, we focus on the macroscopic capillary pressure-saturation (Pc-Sw) relation, which is known to be hysteretic, i.e., this relation is flow process (such as drainage, imbibition and scanning curves) and history dependent. In order to overcome the problem of hysteresis, extended theories of multiphase flow hypothesized that the inclusion of specific interfacial area as a state variable will result in a unique relation between capillary pressure, saturation and interfacial area (Pc-Sw-awn). We study the role of specific interfacial area on hysteresis in the macroscopic Pc-Sw relation under non-equilibrium (dynamic) conditions. Under dynamic conditions, capillary pressure depends on the rate of change of the wetting phase saturation, and the dynamic Pc-Sw relation includes the changes caused by viscous effects. Simulations of drainage and imbibition are performed for two capillary numbers by controlling the flow rate of the non-wetting (polydimenthlysiloxane oil) and wetting (water) fluids. From these simulations, the Pc-Sw curves will be estimated; the Pc-S-awn surface will be constructed to determine whether the data points from drainage and imbibition processes fall on a unique surface under transient conditions. Different macroscopic capillary pressure definitions based on phase-averaged pressures and interfacial area will be evaluated. Understanding macroscopic capillary pressure definitions and the uniqueness of the Pc-S- awn relation is step towards complete description of two-phase flow at the Darcy scale.

Comparative and Developmental Anatomy of Cardiac Lymphatics

PubMed Central

Ratajska, A.; Gula, G.; Flaht-Zabost, A.; Czarnowska, E.; Ciszek, B.; Jankowska-Steifer, E.; Niderla-Bielinska, J.; Radomska-Lesniewska, D.

2014-01-01

The role of the cardiac lymphatic system has been recently appreciated since lymphatic disturbances take part in various heart pathologies. This review presents the current knowledge about normal anatomy and structure of lymphatics and their prenatal development for a better understanding of the proper functioning of this system in relation to coronary circulation. Lymphatics of the heart consist of terminal capillaries of various diameters, capillary plexuses that drain continuously subendocardial, myocardial, and subepicardial areas, and draining (collecting) vessels that lead the lymph out of the heart. There are interspecies differences in the distribution of lymphatic capillaries, especially near the valves, as well as differences in the routes and number of draining vessels. In some species, subendocardial areas contain fewer lymphatic capillaries as compared to subepicardial parts of the heart. In all species there is at least one collector vessel draining lymph from the subepicardial plexuses and running along the anterior interventricular septum under the left auricle and further along the pulmonary trunk outside the heart and terminating in the right venous angle. The second collector assumes a different route in various species. In most mammalian species the collectors run along major branches of coronary arteries, have valves and a discontinuous layer of smooth muscle cells. PMID:24592145

Comparative and developmental anatomy of cardiac lymphatics.

PubMed

Ratajska, A; Gula, G; Flaht-Zabost, A; Czarnowska, E; Ciszek, B; Jankowska-Steifer, E; Niderla-Bielinska, J; Radomska-Lesniewska, D

2014-01-01

The role of the cardiac lymphatic system has been recently appreciated since lymphatic disturbances take part in various heart pathologies. This review presents the current knowledge about normal anatomy and structure of lymphatics and their prenatal development for a better understanding of the proper functioning of this system in relation to coronary circulation. Lymphatics of the heart consist of terminal capillaries of various diameters, capillary plexuses that drain continuously subendocardial, myocardial, and subepicardial areas, and draining (collecting) vessels that lead the lymph out of the heart. There are interspecies differences in the distribution of lymphatic capillaries, especially near the valves, as well as differences in the routes and number of draining vessels. In some species, subendocardial areas contain fewer lymphatic capillaries as compared to subepicardial parts of the heart. In all species there is at least one collector vessel draining lymph from the subepicardial plexuses and running along the anterior interventricular septum under the left auricle and further along the pulmonary trunk outside the heart and terminating in the right venous angle. The second collector assumes a different route in various species. In most mammalian species the collectors run along major branches of coronary arteries, have valves and a discontinuous layer of smooth muscle cells.

Predictive models for moving contact line flows

NASA Technical Reports Server (NTRS)

Rame, Enrique; Garoff, Stephen

2003-01-01

Modeling flows with moving contact lines poses the formidable challenge that the usual assumptions of Newtonian fluid and no-slip condition give rise to a well-known singularity. This singularity prevents one from satisfying the contact angle condition to compute the shape of the fluid-fluid interface, a crucial calculation without which design parameters such as the pressure drop needed to move an immiscible 2-fluid system through a solid matrix cannot be evaluated. Some progress has been made for low Capillary number spreading flows. Combining experimental measurements of fluid-fluid interfaces very near the moving contact line with an analytical expression for the interface shape, we can determine a parameter that forms a boundary condition for the macroscopic interface shape when Ca much les than l. This parameter, which plays the role of an "apparent" or macroscopic dynamic contact angle, is shown by the theory to depend on the system geometry through the macroscopic length scale. This theoretically established dependence on geometry allows this parameter to be "transferable" from the geometry of the measurement to any other geometry involving the same material system. Unfortunately this prediction of the theory cannot be tested on Earth.

Release from the cone ribbon synapse under bright light conditions can be controlled by the opening of only a few Ca(2+) channels.

PubMed

Bartoletti, Theodore M; Jackman, Skyler L; Babai, Norbert; Mercer, Aaron J; Kramer, Richard H; Thoreson, Wallace B

2011-12-01

Light hyperpolarizes cone photoreceptors, causing synaptic voltage-gated Ca(2+) channels to open infrequently. To understand neurotransmission under these conditions, we determined the number of L-type Ca(2+) channel openings necessary for vesicle fusion at the cone ribbon synapse. Ca(2+) currents (I(Ca)) were activated in voltage-clamped cones, and excitatory postsynaptic currents (EPSCs) were recorded from horizontal cells in the salamander retina slice preparation. Ca(2+) channel number and single-channel current amplitude were calculated by mean-variance analysis of I(Ca). Two different comparisons-one comparing average numbers of release events to average I(Ca) amplitude and the other involving deconvolution of both EPSCs and simultaneously recorded cone I(Ca)-suggested that fewer than three Ca(2+) channel openings accompanied fusion of each vesicle at the peak of release during the first few milliseconds of stimulation. Opening fewer Ca(2+) channels did not enhance fusion efficiency, suggesting that few unnecessary channel openings occurred during strong depolarization. We simulated release at the cone synapse, using empirically determined synaptic dimensions, vesicle pool size, Ca(2+) dependence of release, Ca(2+) channel number, and Ca(2+) channel properties. The model replicated observations when a barrier was added to slow Ca(2+) diffusion. Consistent with the presence of a diffusion barrier, dialyzing cones with diffusible Ca(2+) buffers did not affect release efficiency. The tight clustering of Ca(2+) channels, along with a high-Ca(2+) affinity release mechanism and diffusion barrier, promotes a linear coupling between Ca(2+) influx and vesicle fusion. This may improve detection of small light decrements when cones are hyperpolarized by bright light.

Stability limits of unsteady open capillary channel flow

NASA Astrophysics Data System (ADS)

Grah, Aleksander; Haake, Dennis; Rosendahl, Uwe; Klatte, J.?Rg; Dreyer, Michael E.

This paper is concerned with steady and unsteady flow rate limitations in open capillary channels under low-gravity conditions. Capillary channels are widely used in Space technology for liquid transportation and positioning, e.g. in fuel tanks and life support systems. The channel observed in this work consists of two parallel plates bounded by free liquid surfaces along the open sides. The capillary forces of the free surfaces prevent leaking of the liquid and gas ingestion into the flow.In the case of steady stable flow the capillary pressure balances the differential pressure between the liquid and the surrounding constant-pressure gas phase. Increasing the flow rate in small steps causes a decrease of the liquid pressure. A maximum steady flow rate is achieved when the flow rate exceeds a certain limit leading to a collapse of the free surfaces due to the choking effect. In the case of unsteady flow additional dynamic effects take place due to flow rate transition and liquid acceleration. The maximum flow rate is smaller than in the case of steady flow. On the other hand, the choking effect does not necessarily cause surface collapse and stable temporarily choked flow is possible under certain circumstances.To determine the limiting volumetric flow rate and stable flow dynamic properties, a new stability theory for both steady and unsteady flow is introduced. Subcritical and supercritical (choked) flow regimes are defined. Stability criteria are formulated for each flow type. The steady (subcritical) criterion corresponds to the speed index defined by the limiting longitudinal small-amplitude wave speed, similar to the Mach number. The unsteady (supercritical) criterion for choked flow is defined by a new characteristic number, the dynamic index. It is based on pressure balances and reaches unity at the stability limit.The unsteady model based on the Bernoulli equation and the mass balance equation is solved numerically for perfectly wetting incompressible liquids. The unsteady model and the stability theory are verified by comparison to results of a sounding rocket experiment (TEXUS 41) on capillary channel flows launched in December 2005 from ESRANGE in north Sweden. For a clear overview of subcritical, supercritical, and unstable flow, parametric studies and stability diagrams are shown and compared to experimental observations.

Capillary CAA and perivascular Aβ-deposition: two distinct features of Alzheimer's disease pathology.

PubMed

Attems, Johannes; Yamaguchi, Haruyasu; Saido, Takaomi C; Thal, Dietmar Rudolf

2010-12-15

Cerebral amyloid angiopathy (CAA) is frequently seen in Alzheimer's disease (AD) cases and represents one of its histopathological hallmarks. CAA is characterized by amyloid β-protein (Aβ) deposits within vessel walls. In addition to arteries and veins capillaries can also be affected. Aβ deposition into the capillary wall is, thereby, known as capillary CAA (capCAA) and strongly associated with the apolipoprotein E APOEε4 allele as a risk factor. Aβ deposits along the pericapillary glia limitans are described as pericapillary Aβ (pericapAβ: synonymous with pericapillary CAA in other studies). Here, we studied the relationship between pericapAβ and capCAA in 58 human autopsy cases. Although pericapAβ and capCAA were more frequently found in AD cases compared to controls and although they exhibited a correlation to one another, detailed analysis revealed that there is a significant number of cases with pericapAβ lacking capCAA and vice versa. Moreover, single capillaries show either both pathologies or pericapAβ or capCAA only. There was no local association between these pathologies when analyzing multiple capillaries in each given case. Moreover, pericapAβ predominantly exhibited Aβ(42) whereas capCAA contained both Aβ(42) and Aβ(40). These differences as well as differences in the related astroglial reaction indicate that pericapAβ and capCAA are not directly linked. PericapAβ appears to represent initial Aβ accumulation along the glia limitans that is involved in the perivascular drainage of apoE and Aβ regardless of the APOE genotype whereas capCAA could be explained by a limited transendothelial clearance of apoE4-Aβ complexes compared to apoE2/3-Aβ complexes. Copyright © 2010 Elsevier B.V. All rights reserved.

Structural and functional changes in the microcirculation of lepromatous leprosy patients - Observation using orthogonal polarization spectral imaging and laser Doppler flowmetry iontophoresis

PubMed Central

Treu, Curt; de Souza, Maria das Graças Coelho; Lupi, Omar; Sicuro, Fernando Lencastre; Maranhão, Priscila Alves; Kraemer-Aguiar, Luiz Guilherme; Bouskela, Eliete

2017-01-01

Leprosy is a chronic granulomatous infection of skin and peripheral nerves caused by Mycobacterium leprae and is considered the main infectious cause of disability worldwide. Despite the several studies regarding leprosy, little is known about its effects on microvascular structure and function in vivo. Thus, we have aimed to compare skin capillary structure and functional density, cutaneous vasomotion (spontaneous oscillations of arteriolar diameter), which ensures optimal blood flow distribution to skin capillaries) and cutaneous microvascular blood flow and reactivity between ten men with lepromatous leprosy (without any other comorbidity) and ten age- and gender-matched healthy controls. Orthogonal polarization spectral imaging was used to evaluate skin capillary morphology and functional density and laser Doppler flowmetry to evaluate blood flow, vasomotion and spectral analysis of flowmotion (oscillations of blood flow generated by vasomotion) and microvascular reactivity, in response to iontophoresis of acetylcholine and sodium nitroprusside. The contribution of different frequency components of flowmotion (endothelial, neurogenic, myogenic, respiratory and cardiac) was not statistically different between groups. However, endothelial-dependent and -independent vasodilatations elicited by acetylcholine and sodium nitroprusside iontophoresis, respectively, were significantly reduced in lepromatous leprosy patients compared to controls, characterizing the existence of microvascular dysfunction. These patients also presented a significant increase in the number of capillaries with morphological abnormalities and in the diameters of the dermal papilla and capillary bulk when compared to controls. Our results suggest that lepromatous leprosy causes severe microvascular dysfunction and significant alterations in capillary structure. These structural and functional changes are probably induced by exposure of the microvascular bed to chronic inflammation evoked by the Mycobacterium leprae. PMID:28419120

Impact of polymer film thickness and cavity size on polymer flow during embossing : towards process design rules for nanoimprint lithography.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schunk, Peter Randall; King, William P.; Sun, Amy Cha-Tien

2006-08-01

This paper presents continuum simulations of polymer flow during nanoimprint lithography (NIL). The simulations capture the underlying physics of polymer flow from the nanometer to millimeter length scale and examine geometry and thermophysical process quantities affecting cavity filling. Variations in embossing tool geometry and polymer film thickness during viscous flow distinguish different flow driving mechanisms. Three parameters can predict polymer deformation mode: cavity width to polymer thickness ratio, polymer supply ratio, and Capillary number. The ratio of cavity width to initial polymer film thickness determines vertically or laterally dominant deformation. The ratio of indenter width to residual film thickness measuresmore » polymer supply beneath the indenter which determines Stokes or squeeze flow. The local geometry ratios can predict a fill time based on laminar flow between plates, Stokes flow, or squeeze flow. Characteristic NIL capillary number based on geometry-dependent fill time distinguishes between capillary or viscous driven flows. The three parameters predict filling modes observed in published studies of NIL deformation over nanometer to millimeter length scales. The work seeks to establish process design rules for NIL and to provide tools for the rational design of NIL master templates, resist polymers, and process parameters.« less

π-Conjugated polymer anisotropic organogel nanofibrous assemblies for thermoresponsive photonic switches.

PubMed

Narasimha, Karnati; Jayakannan, Manickam

2014-11-12

The present work demonstrates one of the first examples of π-conjugated photonic switches (or photonic wave plates) based on the tailor-made π-conjugated polymer anisotropic organogel. New semicrystalline segmented π-conjugated polymers are designed with rigid aromatic oligophenylenevinylene π-core and flexible alkyl chain along the polymer backbone. These polymers are found to be self-assembled as semicrystalline or amorphous with respect to the number of carbon atoms in the alkyl units. These semicrystalline polymers produce organogels having nanofibrous morphology of 20 nm thickness with length up to 5 μm. The polymer organogel is aligned in a narrow glass capillary, and this anisotropic gel device is further demonstrated as photonic switches. The glass capillary device behaves as typical λ/4 photonic wave plates upon the illumination of the plane polarized light. The λ/4 photonic switching ability is found to be maximum at θ = 45° angle under the cross polarizers. The orthogonal arrangements of the gel capillaries produce dark and bright spots as on-and-off optical switches. Thermoreversibility of the polymer organogel (also its xerogel) was exploited to construct thermoresponsive photonic switches for the temperature window starting from 25 to 160 °C. The organic photonic switch concept can be adapted to large number of other π-conjugated materials for optical communication and storage.

Influence of Inertial, Visous and Capillary Effects on the Apical Behavior of Taylor Cone Formation in Liquid Metals

NASA Astrophysics Data System (ADS)

Albertson, Theodore; Troian, Sandra

Above a critical applied field strength, the surface of a liquid metal can deform into a conical shape whose apex can emit ions. The precursor shape and dynamics to that event have been debated for decades. In a landmark paper, Zubarev (2001) invoked potential flow theory to predict the existence of self-similar apical sharpening for the case of an ideal perfectly conducting liquid. He found that the Maxwell and capillary pressures at the cone tip scale in time as -2/3 upon approach to the singularity. In this talk, we examine the behavior of thin electrified microscale films placed in close proximity to a grounded planar counter electrode to probe how inertial and viscous forces, diminished or neglected in the original analysis, modify the power law exponents governing the apical self-similar regime. We employ finite element, moving mesh simulations to investigate these effects for low, intermediate and high electric Reynolds and capillary numbers. We confirm the robustness of the self-similar regime characterized by power law exponents despite the lack of potential flow - however, the power law exponents, no longer -2/3, assume values which depend on the choice of dimensionless numbers. TGA gratefully acknowledges support from a NASA Space Technology Research Fellowship.

Lubrication Flows.

ERIC Educational Resources Information Center

Papanastasiou, Tasos C.

1989-01-01

Discusses fluid mechanics for undergraduates including the differential Navier-Stokes equations, dimensional analysis and simplified dimensionless numbers, control volume principles, the Reynolds lubrication equation for confined and free surface flows, capillary pressure, and simplified perturbation techniques. Provides a vertical dip coating…

Airway remodeling associated with cough hypersensitivity as a consequence of persistent cough: An experimental study.

PubMed

Nakaji, Hitoshi; Niimi, Akio; Matsuoka, Hirofumi; Iwata, Toshiyuki; Cui, Shilei; Matsumoto, Hisako; Ito, Isao; Oguma, Tsuyoshi; Otsuka, Kojiro; Takeda, Tomoshi; Inoue, Hideki; Tajiri, Tomoko; Nagasaki, Tadao; Kanemitsu, Yoshihiro; Chin, Kazuo; Mishima, Michiaki

2016-11-01

Chronic cough involves airway remodeling associated with cough reflex hypersensitivity. Whether cough itself induces these features remains unknown. Guinea pigs were assigned to receive treatment with citric acid (CA), saline (SA), or CA+dextromethorphan (DEX). All animals were exposed to 0.5M CA on days 1 and 22. On days 4-20, the CA and CA+DEX groups were exposed to CA, and the SA group to saline thrice weekly, during which the CA+DEX group was administered DEX pretreatment to inhibit cough. The number of coughs was counted during each 10-min CA or SA exposure. Terbutaline premedication was started to prevent bronchoconstriction. Bronchoalveolar lavage and pathology were examined on day 25. Average cough number for 10 CA exposures was examined as "cough index" in the CA group, which was divided into frequent (cough index>5) and infrequent (<5) cough subgroups for lavage and pathology analysis. The number of coughs significantly increased in the CA group from day 13 onwards. In the CA+DEX and SA groups, the number of coughs did not differ between days 1 and 22, while average number of coughs during days 4-20 was significantly lower than at days 1 and 22. Bronchoalveolar cell profiles were similar among the four groups. The smooth muscle area of small airways was significantly greater in the frequent-cough subgroup than in the other groups (in which it was similar), and highly correlated with cough index in CA group. Repeated cough induces airway smooth muscle remodeling associated with cough reflex hypersensitivity. Copyright © 2016 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved.

Distribution of rSlo Ca2+-activated K+ channels in rat astrocyte perivascular endfeet.

PubMed

Price, Diana L; Ludwig, Jeffrey W; Mi, Huaiyu; Schwarz, Thomas L; Ellisman, Mark H

2002-11-29

Evidence that Ca(2+)-activated K(+) (K(Ca)) channels play a role in cell volume changes and K(+) homeostasis led to a prediction that astrocytes would have K(Ca) channels near blood vessels in order to maintain K(+) homeostasis. Consistent with this thinking the present study demonstrates that rSlo K(Ca) channels are in glial cells of the adult rat central nervous system (CNS) and highly localized to specializations of astrocytes associated with the brain vasculature. Using confocal and thin-section electron microscopic immunolabeling methods the distribution of rSlo was examined in adult rat brain. Strong rSlo immunolabeling was present around the vasculature of most brain regions. Examination of dye-filled hippocampal astrocytes revealed rSlo immunolabeling polarized in astrocytic endfeet. Ultrastructural analysis confirmed that the rSlo staining was concentrated in astrocytic endfeet ensheathing capillaries as well as abutting the pia mater. Immunostaining within the endfeet was predominantly distributed at the plasma membrane directly adjacent to either the vascular basal lamina or the pial surface. The distribution of the aquaporin-4 (AQP-4) water channel was also examined using dye-filled hippocampal astrocytes. In confirmation of earlier reports, intense AQP-4 immunolabeling was generally observed at the perimeter of blood vessels, and coincided with perivascular endfeet and rSlo labeling. We propose that rSlo K(Ca) channels, with their sensitivity to membrane depolarization and intracellular calcium, play a role in the K(+) modulation of cerebral blood flow. Additional knowledge of the molecular and cellular machinery present at perivascular endfeet may provide insight into the structural and functional molecular elements responsible for the neuronal activity-dependent regulation of cerebral blood flow. Copyright 2002 Elsevier Science B.V.

Simultaneous enhancement of sludge dewaterability and removal of sludge-borne heavy metals through a novel oxidative leaching induced by nano-CaO2.

PubMed

Wu, Boran; Dai, Xiaohu; Chai, Xiaoli

2017-07-01

The production of sewage sludge with the presence of various contaminants has been a serious issue for the operation of wastewater treatment plants on both the economical and environmental sides. To minimize the sludge volume to be handled and limit the potential environmental risk, this study developed a novel oxidative leaching process for enhanced sewage sludge dewatering and simultaneous removal of heavy metals based on nano-CaO 2 . Response surface methodology determined the following optimal conditioning parameters in terms of capillary suction time reduction: 0.0906 g/g dry solid (DS) nano-CaO 2 , 0.9969 mmol/g DS Fe 2+ , and pH of 5.59. The speciation partitioning analysis of the heavy metals pre and post nano-CaO 2 peroxidation indicated that the content of organically bound metals decreased and the percentage of soluble fraction increased substantially, which was beneficial for the removal of heavy metals through the dewatering unit. Nano-CaO 2 peroxidation could also induce the transformation of extracellular polymeric substances (EPS) from the tightly bound layers to the loosely bound layers of sewage sludge flocs. Through the decline of the Ryan-Weber constant of fluorescence titration and the pseudo-first-order kinetic constant of complexation, it was verified that the binding capacity of EPS with metal ions could be damaged by nano-CaO 2 peroxidation, which was the primary mechanism behind the substantial reduction of organically bound metals. This study is believed to provide novel insights into the application of nanotechnology in terms of the simultaneous volume and toxicity reduction of sewage sludge. Graphical abstract.

Microvasculature of crotaline snake pit organs: possible function as a heat exchange mechanism.

PubMed

Amemiya, F; Nakano, M; Goris, R C; Kadota, T; Atobe, Y; Funakoshi, K; Hibiya, K; Kishida, R

1999-01-01

The infrared sensory membranes of the pit organs of pit vipers have an extremely rich capillary vasculature, which has been noted passim in the literature, but never illustrated or studied in detail. We rendered the pit vasculature visible in various ways, namely, by microinjection of India ink, by a combination of ink and succinate dehydrogenase staining, and by making resin casts for scanning electron microscope study. We also used transmission electron microscopy for identifying the types (arterioles, venules, capillaries) of blood vessels. Then we compared the pit vasculature with that of the retina and the dermis. Good visualization of the vasculature was obtained with both ink and resin injection. Arterioles, venules, and capillaries could be distinguished with all methods used. The monolayer vasculature was denser in the pit membrane than in the retina or skin. Each loop of the network enclosed a small number of infrared receptors so that all receptors were in contact with a capillary on at least one side. The forward-looking areas of the pit had a denser network than side-looking areas. Since infrared rays cause nerve impulses by raising the temperature of individual receptors, the capillary network functions not only as a supplier of energy but also as a cooling mechanism to reduce afterimages. Thus the denser network in the forward-looking areas causes these areas to be more sensitive and have better image resolution than the rest of the membrane.

Tunable thick porous silica coating fabricated by multilayer-by-multilayer bonding of silica nanoparticles for open-tubular capillary chromatographic separation.

PubMed

Qu, Qishu; Liu, Yuanyuan; Shi, Wenjun; Yan, Chao; Tang, Xiaoqing

2015-06-19

A simple coating procedure employing a multilayer-by-multilayer process to modify the inner surface of bare fused-silica capillaries with silica nanoparticles was established. The silica nanoparticles were adsorbed onto the capillary wall via a strong electrostatic interaction between amino functional groups and silica particles. The thickness of the coating could be tuned from 130 to 600 nm by increasing the coating cycles from one to three. Both the retention factor and the resolution were greatly increased with increasing coating cycles. The loading capacity determined by naphthalene in the column with three coating cycles is 152.1 pmol. The effects of buffer concentration and pH value on the stability of the coating were evaluated. The retention reproducibility of the separation of toluene was 0.8, 1.2, 2.3, and 4.5%, respectively, for run-to-run, day-to-day, column-to-column, and batch-to-batch, respectively. The chromatographic performance of these columns was evaluated by both capillary liquid chromatography and open-tubular capillary electrochromatography (OT-CEC). Separation of aromatic hydrocarbons in the column with three coating cycles provided high theoretical plate numbers (up to 269,280 plates m(-1) for toluene) and short separation time (<15 min) by using OT-CEC mode. The method was also used to separate egg white proteins. Both acidic and basic proteins as well as four glycoisoforms were separated in a single run. Copyright © 2015 Elsevier B.V. All rights reserved.

Blood Vessel Adaptation with Fluctuations in Capillary Flow Distribution

PubMed Central

Hu, Dan; Cai, David; Rangan, Aaditya V.

2012-01-01

Throughout the life of animals and human beings, blood vessel systems are continuously adapting their structures – the diameter of vessel lumina, the thickness of vessel walls, and the number of micro-vessels – to meet the changing metabolic demand of the tissue. The competition between an ever decreasing tendency of luminal diameters and an increasing stimulus from the wall shear stress plays a key role in the adaptation of luminal diameters. However, it has been shown in previous studies that the adaptation dynamics based only on these two effects is unstable. In this work, we propose a minimal adaptation model of vessel luminal diameters, in which we take into account the effects of metabolic flow regulation in addition to wall shear stresses and the decreasing tendency of luminal diameters. In particular, we study the role, in the adaptation process, of fluctuations in capillary flow distribution which is an important means of metabolic flow regulation. The fluctuation in the flow of a capillary group is idealized as a switch between two states, i.e., an open-state and a close-state. Using this model, we show that the adaptation of blood vessel system driven by wall shear stress can be efficiently stabilized when the open time ratio responds sensitively to capillary flows. As micro-vessel rarefaction is observed in our simulations with a uniformly decreased open time ratio of capillary flows, our results point to a possible origin of micro-vessel rarefaction, which is believed to induce hypertension. PMID:23029014

Characteristics and dispersity of a two gap capillary discharge applied for long spark gap ignition in air

NASA Astrophysics Data System (ADS)

Huang, Dong; Yang, Lanjun; Guo, Haishan; Zhang, Zhiyuan; Jiang, Hongqiu; Xu, Haipeng

2017-07-01

In this paper, the characteristics and dispersity of a two gap capillary (TGC) discharge applied for long spark gap ignition are studied. Under the same discharge condition, 30 repetitive discharges are done to get a certain number of data samples. Accordingly, the change trend of the characteristics and the dispersity with the charging voltage of C1 are analyzed statistically. The delay of soft capillary discharge is determined by the saturation rate of the magnetic core of the pulse transformer and decreases with the increase in the charging voltage. The main discharge delay decreases from 1.0 kV to 2.0 kV and stops the decreasing trend when the charging voltage increases to 2.5 kV. In contrast, the current amplitude of soft capillary discharge and main discharge increases with charging voltage. Long tail extinction is witnessed at the charging voltage of 1.0 kV and the major cause is the insufficient pressure in the post discharge. The waveform of the capillary arc resistivity is U-like shape and the minimum resistivity decreases with the increase in the charging voltage. Meanwhile, the arc resistivity in the ascending stage is much higher than that in the descending stage with the same value of the discharge current. The energy consumption of the TGC discharge can be mainly divided into four parts and more than 70% of the energy is consumed in main discharge.

Monitoring compliance to therapy during addiction treatments by means of hair analysis for drugs and drug metabolites using capillary zone electrophoresis coupled to time-of-flight mass spectrometry.

PubMed

Gottardo, Rossella; Fanigliulo, Ameriga; Sorio, Daniela; Liotta, Eloisa; Bortolotti, Federica; Tagliaro, Franco

2012-03-10

Capillary electrophoresis coupled to time-of-flight mass spectrometry was used in the present work for the determination of therapeutic and abused drugs and their metabolites in the hair of subjects undergoing addiction treatments, in order to monitor their compliance to therapy. For this purpose a rapid, qualitative drug screening method was adopted based on capillary electrophoresis hyphenated with time-of-flight mass spectrometry, which had earlier been developed and validated for the forensic-toxicological analysis of hair, limitedly to illicit/abused drugs [1]. Sampling of hair was carried out in order to refer to a time window of about two months from the date of sampling (i.e. 2cm ca. from cortex). A single extraction procedure was applied, allowing the determination in the hair matrix of "drugs of abuse" referred to the past abuses, and therapeutic drugs prescribed in the detoxification program as well as their metabolites. Analyte identification was based on accurate mass measurements and comparison of isotope patterns, providing the most likely matching between accurate mass value and elemental formula. Small molecules (<500Da) of forensic and toxicological interest could be identified unambiguously using mass spectrometric conditions tailored to meet a mass accuracy ≤5ppm. In the present study, the proposed approach proved suitable for the rapid broad spectrum screening of hair samples, although needing further confirmation of results by using fragmentation mass spectrometry. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Combination of ICP-MS, capillary electrophoresis, and their hyphenation for probing Ru(III) metallodrug-DNA interactions.

PubMed

Foteeva, Lidia S; Matczuk, Magdalena; Pawlak, Katarzyna; Aleksenko, Svetlana S; Nosenko, Sergey V; Karandashev, Vasily K; Jarosz, Maciej; Timerbaev, Andrei R

2017-03-01

Determination of the DNA-binding reactivity and affinity is an important part of a successful program for the selection of metallodrug candidates. For such assaying, a range of complementary analytical techniques was proposed and tested here using one of few anticancer metal-based drugs that are currently in clinical trials, indazolium trans-[tetrachloridobis(1H-indazole)ruthenate(III), and a DNA oligonucleotide. A high reactivity of the Ru drug was confirmed in affinity capillary electrophoresis (CE) mode, where adduct formation takes place in situ (i.e., in the capillary filled with an oligonucleotide-containing electrolyte). To further characterize the binding kinetics, a drug-oligonucleotide mixture was incubated for a different period of time, followed by ultrafiltration separation into two different in molecular weight fractions (>3 and <3 kDa). The time-dependent distribution profiles of the Ru drug were then assessed by CE-inductively coupled plasma mass spectrometry (ICP-MS), revealing that at least two DNA adducts exist at equilibrium conditions. Using standalone ICP-MS, dominant equilibrium amount of the bound ruthenium was found to occur in a fraction of 5-10 kDa, which includes the oligonucleotide (ca. 6 kDa). Importantly, in all three assays, the drug was used for the first time in in-vitro studies, not in the intact form but as its active species released from the transferrin adduct at simulated cancer cytosolic conditions. This circumstance makes the established analytical platform promising to provide a detailed view on metallodrug targeting, including other possible biomolecules and ex vivo samples.

Effects of deoxygenation on active and passive Ca2+ transport and cytoplasmic Ca2+ buffering in normal human red cells.

PubMed Central

Tiffert, T; Etzion, Z; Bookchin, R M; Lew, V L

1993-01-01

1. The effects of deoxygenation on cytoplasmic Ca2+ buffering, saturated Ca2+ extrusion rate through the Ca2+ pump (Vmax), passive Ca2+ influx and physiological [Ca2+]i level were investigated in human red cells to assess whether or not their Ca2+ metabolism might be altered by deoxygenation in capillaries and venous circulation. 2. The study was performed in fresh human red cells maintained in a tonometer either fully oxygenated or deoxygenated. Cytoplasmic Ca2+ buffering was estimated from the equilibrium distribution of 45Ca2+ induced by the divalent cation ionophore A23187 and the Vmax of the Ca2+ pump was measured either by the Co(2+)-exposure method or following ionophore wash-out. The passive Ca2+ influx and physiological [Ca2+]i were determined in cells preloaded with the Ca2+ chelator benz-2 and resuspended in autologous plasma. 3. Deoxygenation increased the fraction of ionized Ca2+ in cell water by 34-74% and reduced the Vmax of the Ca2+ pump by 18-32%. 4. To elucidate whether or not these effects were secondary to deoxygenation-induced pH shifts, the effects of deoxygenation on cell and medium pH, and of pH on cytoplasmic Ca2+ binding and Ca2+ pump Vmax in oxygenated cells were examined in detail. 5. Deoxygenation generated large alkaline pH shifts that could be explained if the apparent isoelectric point (pI) of haemoglobin increased by 0.2-0.4 pH units in intact cells, consistently higher than the value of 0.15 reported for pure haemoglobin solutions. 6. In oxygenated cells, the fraction of ionized cell calcium, alpha, was little affected by pH within the 7.0-7.7 range. Ca2+ pump Vmax was maximal at a medium pH of about 7.55. Comparison between pH effects elicited by HCl-NaOH additions and by replacing Cl- with gluconate suggested that Vmax was inhibited by both internal acidification and external alkalinization. Since deoxygenation alkalinized cells and medium within a range stimulatory for Vmax, the inhibition observed was not due to pH. 7. There was no significant effect of deoxygenation on passive Ca2+ uptake, or steady-state physiological [Ca2+]i level. 8. The deoxygenation-induced reduction in Ca2+ binding capacity may result from the increased protonation of haemoglobin on deoxygenation and from binding of 2,3-diphosphoglyceric acid (2,3-DPG) and ATP to deoxyhaemoglobin; inhibition of the Ca2+ pump may result from shifts in the [Mg2+]i/[ATP]i ratio away from a near optimal stimulatory value in the oxygenated state. PMID:8229816

Microfluidic breakups of confined droplets against a linear obstacle: The importance of the viscosity contrast

NASA Astrophysics Data System (ADS)

Salkin, Louis; Courbin, Laurent; Panizza, Pascal

2012-09-01

Combining experiments and theory, we investigate the break-up dynamics of deformable objects, such as drops and bubbles, against a linear micro-obstacle. Our experiments bring the role of the viscosity contrast Δη between dispersed and continuous phases to light: the evolution of the critical capillary number to break a drop as a function of its size is either nonmonotonic (Δη>0) or monotonic (Δη≤0). In the case of positive viscosity contrasts, experiments and modeling reveal the existence of an unexpected critical object size for which the critical capillary number for breakup is minimum. Using simple physical arguments, we derive a model that well describes observations, provides diagrams mapping the four hydrodynamic regimes identified experimentally, and demonstrates that the critical size originating from confinement solely depends on geometrical parameters of the obstacle.

Coalescence of viscous drops translating through a capillary tube

NASA Astrophysics Data System (ADS)

AlMatroushi, Eisa; Borhan, Ali

2014-03-01

An experimental study of the interaction and coalescence of viscous drops moving through a cylindrical capillary tube under low Reynolds number conditions is presented. The combined pressure- and buoyancy-driven motion of drops in a Newtonian continuous phase is examined. The interaction between two drops is quantified using image analysis, and measurements of the coalescence time are reported for various drop size ratios, Bond numbers, and viscosity ratios. The time scale for coalescence in the non-axisymmetric configuration is found to be substantially larger than that for coalescence in the axisymmetric configuration. Measurements of the radius of the liquid film formed between the two drops at the instant of apparent contact are used in conjunction with a planar film drainage model to predict the dependence of the coalescence time on drop size ratio for coalescence of low viscosity-ratio drops in the axisymmetric configuration.

Dispersive effects on multicomponent transport through porous media

NASA Astrophysics Data System (ADS)

Dutta, Sourav; Daripa, Prabir

2017-11-01

We use a hybrid numerical method to solve a global pressure based porous media flow model of chemical enhanced oil recovery. This is an extension of our recent work. The numerical method is based on the use of a discontinuous finite element method and the modified method of characteristics. The impact of molecular diffusion and mechanical dispersion on the evolution of scalar concentration distributions are studied through numerical simulations of various flooding schemes. The relative importance of the advective, capillary diffusive and dispersive fluxes are compared over different flow regimes defined in the parameter space of Capillary number, Peclet number, longitudinal and transverse dispersion coefficients. Such studies are relevant for the design of effective injection policies and determining optimal combinations of chemical components for improving recovery. This work has been possible due to financial support from the U.S. National Science Foundation Grant DMS-1522782.

Effects of Pleiotrophin Overexpression on Mouse Skeletal Muscles in Normal Loading and in Actual and Simulated Microgravity

PubMed Central

Liantonio, Antonella; De Bellis, Michela; Cannone, Maria; Sblendorio, Valeriana; Conte, Elena; Mele, Antonietta; Tricarico, Domenico; Tavella, Sara; Ruggiu, Alessandra; Cancedda, Ranieri; Ohira, Yoshinobu; Danieli-Betto, Daniela; Ciciliot, Stefano; Germinario, Elena; Sandonà, Dorianna; Betto, Romeo; Desaphy, Jean-François

2013-01-01

Pleiotrophin (PTN) is a widespread cytokine involved in bone formation, neurite outgrowth, and angiogenesis. In skeletal muscle, PTN is upregulated during myogenesis, post-synaptic induction, and regeneration after crushing, but little is known regarding its effects on muscle function. Here, we describe the effects of PTN on the slow-twitch soleus and fast-twitch extensor digitorum longus (EDL) muscles in mice over-expressing PTN under the control of a bone promoter. The mice were maintained in normal loading or disuse condition, induced by hindlimb unloading (HU) for 14 days. Effects of exposition to near-zero gravity during a 3-months spaceflight (SF) into the Mice Drawer System are also reported. In normal loading, PTN overexpression had no effect on muscle fiber cross-sectional area, but shifted soleus muscle toward a slower phenotype, as shown by an increased number of oxidative type 1 fibers, and increased gene expression of cytochrome c oxidase subunit IV and citrate synthase. The cytokine increased soleus and EDL capillary-to-fiber ratio. PTN overexpression did not prevent soleus muscle atrophy, slow-to-fast transition, and capillary regression induced by SF and HU. Nevertheless, PTN exerted various effects on sarcolemma ion channel expression/function and resting cytosolic Ca2+ concentration in soleus and EDL muscles, in normal loading and after HU. In conclusion, the results show very similar effects of HU and SF on mouse soleus muscle, including activation of specific gene programs. The EDL muscle is able to counterbalance this latter, probably by activating compensatory mechanisms. The numerous effects of PTN on muscle gene expression and functional parameters demonstrate the sensitivity of muscle fibers to the cytokine. Although little benefit was found in HU muscle disuse, PTN may emerge useful in various muscle diseases, because it exerts synergetic actions on muscle fibers and vessels, which could enforce oxidative metabolism and ameliorate muscle performance. PMID:24015201

A Study of Crystalline Mechanism of Penetration Sealer Materials.

PubMed

Teng, Li-Wei; Huang, Ran; Chen, Jie; Cheng, An; Hsu, Hui-Mi

2014-01-14

It is quite common to dispense a topping material like crystalline penetration sealer materials (CPSM) onto the surface of a plastic substance such as concrete to extend its service life span by surface protections from outside breakthrough. The CPSM can penetrate into the existing pores or possible cracks in such a way that it may form crystals to block the potential paths which provide breakthrough for any unknown materials. This study investigated the crystalline mechanism formed in the part of concrete penetrated by the CPSM. We analyzed the chemical composites, in order to identify the mechanism of CPSM and to evaluate the penetrated depth. As shown in the results, SEM observes the acicular-structured crystals filling capillary pores for mortar substrate of the internal microstructure beneath the concrete surface; meanwhile, XRD and FT-IR showed the main hydration products of CPSM to be C-S-H gel and CaCO₃. Besides, MIP also shows CPSM with the ability to clog capillary pores of mortar substrate; thus, it reduces porosity, and appears to benefit in sealing pores or cracks. The depth of CPSM penetration capability indicated by TGA shows 0-10 mm of sealer layer beneath the concrete surface.

Release from the cone ribbon synapse under bright light conditions can be controlled by the opening of only a few Ca2+ channels

PubMed Central

Bartoletti, Theodore M.; Jackman, Skyler L.; Babai, Norbert; Mercer, Aaron J.; Kramer, Richard H.

2011-01-01

Light hyperpolarizes cone photoreceptors, causing synaptic voltage-gated Ca2+ channels to open infrequently. To understand neurotransmission under these conditions, we determined the number of L-type Ca2+ channel openings necessary for vesicle fusion at the cone ribbon synapse. Ca2+ currents (ICa) were activated in voltage-clamped cones, and excitatory postsynaptic currents (EPSCs) were recorded from horizontal cells in the salamander retina slice preparation. Ca2+ channel number and single-channel current amplitude were calculated by mean-variance analysis of ICa. Two different comparisons—one comparing average numbers of release events to average ICa amplitude and the other involving deconvolution of both EPSCs and simultaneously recorded cone ICa—suggested that fewer than three Ca2+ channel openings accompanied fusion of each vesicle at the peak of release during the first few milliseconds of stimulation. Opening fewer Ca2+ channels did not enhance fusion efficiency, suggesting that few unnecessary channel openings occurred during strong depolarization. We simulated release at the cone synapse, using empirically determined synaptic dimensions, vesicle pool size, Ca2+ dependence of release, Ca2+ channel number, and Ca2+ channel properties. The model replicated observations when a barrier was added to slow Ca2+ diffusion. Consistent with the presence of a diffusion barrier, dialyzing cones with diffusible Ca2+ buffers did not affect release efficiency. The tight clustering of Ca2+ channels, along with a high-Ca2+ affinity release mechanism and diffusion barrier, promotes a linear coupling between Ca2+ influx and vesicle fusion. This may improve detection of small light decrements when cones are hyperpolarized by bright light. PMID:21880934

Verification of an analytic modeler for capillary pump loop thermal control systems

NASA Technical Reports Server (NTRS)

Schweickart, R. B.; Neiswanger, L.; Ku, J.

1987-01-01

A number of computer programs have been written to model two-phase heat transfer systems for space use. These programs support the design of thermal control systems and provide a method of predicting their performance in the wide range of thermal environments of space. Predicting the performance of one such system known as the capillary pump loop (CPL) is the intent of the CPL Modeler. By modeling two developed CPL systems and comparing the results with actual test data, the CPL Modeler has proven useful in simulating CPL operation. Results of the modeling effort are discussed, together with plans for refinements to the modeler.

Marangoni effect on small-amplitude capillary waves in viscous fluids

NASA Astrophysics Data System (ADS)

Shen, Li; Denner, Fabian; Morgan, Neal; van Wachem, Berend; Dini, Daniele

2017-11-01

We derive a general integro-differential equation for the transient behavior of small-amplitude capillary waves on the planar surface of a viscous fluid in the presence of the Marangoni effect. The equation is solved for an insoluble surfactant solution in concentration below the critical micelle concentration undergoing convective-diffusive surface transport. The special case of a diffusion-driven surfactant is considered near the the critical damping wavelength. The Marangoni effect is shown to contribute to the overall damping mechanism, and a first-order term correction to the critical wavelength with respect to the surfactant concentration difference and the Schmidt number is proposed.

Big Hydrophobic Capillary Fluidics; Basically Water Ping Pong in Space

NASA Astrophysics Data System (ADS)

Weislogel, Mark; Attari, Babak; Wollman, Andrew; Cardin, Karl; Geile, John; Lindner, Thomas

2016-11-01

Capillary surfaces can be enormous in environments where the effects of gravity are small. In this presentation we review a number of interesting examples from demonstrative experiments performed in drop towers and aboard the International Space Station. The topic then focuses on large length scale hydrophobic phenomena including puddle jumping, spontaneous particle ejections, and large drop rebounds akin to water ping pong in space. Unseen footage of NASA Astronaut Scott Kelly playing water ping pong in space will be shown. Quantitative and qualitative results are offered to assist in the design of experiments for ongoing research. NASA NNX12A047A.

Bubble propagation in Hele-Shaw channels with centred constrictions

NASA Astrophysics Data System (ADS)

Franco-Gómez, Andrés; Thompson, Alice B.; Hazel, Andrew L.; Juel, Anne

2018-04-01

We study the propagation of finite bubbles in a Hele-Shaw channel, where a centred occlusion (termed a rail) is introduced to provide a small axially uniform depth constriction. For bubbles wide enough to span the channel, the system’s behaviour is similar to that of semi-infinite fingers and a symmetric static solution is stable. Here, we focus on smaller bubbles, in which case the symmetric static solution is unstable and the static bubble is displaced towards one of the deeper regions of the channel on either side of the rail. Using a combination of experiments and numerical simulations of a depth-averaged model, we show that a bubble propagating axially due to a small imposed flow rate can be stabilised in a steady symmetric mode centred on the rail through a subtle interaction between stabilising viscous forces and destabilising surface tension forces. However, for sufficiently large capillary numbers Ca, the ratio of viscous to surface tension forces, viscous forces in turn become destabilising thus returning the bubble to an off-centred propagation regime. With decreasing bubble size, the range of Ca for which steady centred propagation is stable decreases, and eventually vanishes through the coalescence of two supercritical pitchfork bifurcations. The depth-averaged model is found to accurately predict all the steady modes of propagation observed experimentally, and provides a comprehensive picture of the underlying steady bifurcation structure. However, for sufficiently large imposed flow rates, we find that initially centred bubbles do not converge onto a steady mode of propagation. Instead they transiently explore weakly unstable steady modes, an evolution which results in their break-up and eventual settling into a steady propagating state of changed topology.

Simulation, Measurements and Image Processing for Capillary Optical Digital Mammography

DTIC Science & Technology

2000-07-01

is the length of the optic. For a point P on the film, scattered radiation could come from any direction in the solid angle Qpatient , which is the...optic p .’optic - N, = T + npatient (13) where Ns-optic is the number of scattered x rays with the optic, N, is the number of scattered x rays without

Multiple-Locus Variable-Number Tandem-Repeats Analysis of Escherichia coli O157 using PCR multiplexing and multi-colored capillary electrophoresis.

PubMed

Lindstedt, Bjørn-Arne; Vardund, Traute; Kapperud, Georg

2004-08-01

The Multiple-Locus Variable-Number Tandem-Repeats Analysis (MLVA) method is currently being used as the primary typing tool for Shiga-toxin-producing Escherichia coli (STEC) O157 isolates in our laboratory. The initial assay was performed using a single fluorescent dye and the different patterns were assigned using a gel image. Here, we present a significantly improved assay using multiple dye colors and enhanced PCR multiplexing to increase speed, and ease the interpretation of the results. The different MLVA patterns are now based on allele sizes entered as character values, thus removing the uncertainties introduced when analyzing band patterns from the gel image. We additionally propose an easy numbering scheme for the identification of separate isolates that will facilitate exchange of typing data. Seventy-two human and animal strains of Shiga-toxin-producing E. coli O157 were used for the development of the improved MLVA assay. The method is based on capillary separation of multiplexed PCR products of VNTR loci in the E. coli O157 genome labeled with multiple fluorescent dyes. The different alleles at each locus were then assigned to allele numbers, which were used for strain comparison.

Determination of somatropin charged variants by capillary zone electrophoresis - optimisation, verification and implementation of the European pharmacopoeia method.

PubMed

Storms, S M; Feltus, A; Barker, A R; Joly, M-A; Girard, M

2009-03-01

Measurement of somatropin charged variants by isoelectric focusing was replaced with capillary zone electrophoresis in the January 2006 European Pharmacopoeia Supplement 5.3, based on results from an interlaboratory collaborative study. Due to incompatibilities and method-robustness issues encountered prior to verification, a number of method parameters required optimisation. As the use of a diode array detector at 195 nm or 200 nm led to a loss of resolution, a variable wavelength detector using a 200 nm filter was employed. Improved injection repeatability was obtained by increasing the injection time and pressure, and changing the sample diluent from water to running buffer. Finally, definition of capillary pre-treatment and rinse procedures resulted in more consistent separations over time. Method verification data are presented demonstrating linearity, specificity, repeatability, intermediate precision, limit of quantitation, sample stability, solution stability, and robustness. Based on these experiments, several modifications to the current method have been recommended and incorporated into the European Pharmacopoeia to help improve method performance across laboratories globally.

High hydrostatic pressures in traumatic joints require elevated synovial capillary pressure probably associated with arteriolar vasodilatation.

PubMed

Ahlqvist, J; Harilainen, A; Aalto, K; Sarna, S; Lalla, M; Osterlund, K

1994-11-01

Three out of the four Starling pressures were determined at arthroscopy of traumatic effusions of the knee. The range of the joint fluid hydrostatic pressure Pjoint was 5-83 cmH2O (0.5-8.1 kPa, 4-61 mmHg), that of the colloid osmotic pressure difference COPplasma-COPjoint 0-21.7 cmH2O. In 11 of 15 cases the sum Pjoint+COP difference exceeded 32.6 cmH2O (3.19 kPa, 24 mmHg), a high estimate of average capillary pressure at the level of the heart. The number of 'exceeding' cases was 8/15 if only 80% of the COP difference was considered effective. Pjoint and the COP difference oppose filtration of fluid from plasma into joints, indicating that mean capillary pressure, the only Starling pressure not determined, was elevated unless the effusions were being resorbed back into the blood. The findings can be explained by tamponade compensated by arteriolar vasodilatation, suspected to be metabolically mediated.

Analysis of mutational spectra by denaturant capillary electrophoresis

PubMed Central

Ekstrøm, Per O.; Khrapko, Konstantin; Li-Sucholeiki, Xiao-Cheng; Hunter, Ian W.; Thilly, William G.

2009-01-01

Numbers and kinds of point mutant within DNA from cells, tissues and human population may be discovered for nearly any 75–250bp DNA sequence. High fidelity DNA amplification incorporating a thermally stable DNA “clamp” is followed by separation by denaturing capillary electrophoresis (DCE). DCE allows for peak collection and verification sequencing. DCE in a mode of cycling temperature, e.g.+/− 5°C, CyDCE, permits high resolution of mutant sequences using computer defined analytes without preliminary optimization experiments. DNA sequencers have been modified to permit higher throughput CyDCE and a massively parallel,~25,000 capillary system, has been designed for pangenomic scans in large human populations. DCE has been used to define quantitative point mutational spectra for study a wide variety of genetic phenomena: errors of DNA polymerases, mutations induced in human cells by chemicals and irradiation, testing of human gene-common disease associations and the discovery of origins of point mutations in human development and carcinogenesis. PMID:18600220

Drainage Behavior in Soap Films Above and Below the CMC

NASA Astrophysics Data System (ADS)

Berg, S.; Adelizzi, E. A.; Troian, S. M.

2003-11-01

We investigate through laser interferometry the drainage behavior of Newtonian soap films initially entrained on a fiber frame at small and constant capillary number. The initial film thickness is sufficiently small that gravitational drainage is presumed minimal. The drainage of rigid soap films by capillary forces alone should proceed according to h(t) ˜ t^- 1/2. Our experimental results show much more rapid drainage with exponents as large as -2, especially for those solutions whose surfactant concentrations are below the CMC. Video recordings of the entire film surface reveal a variety of structures during the drainage process, some attributable to marginal regeneration. Though still a controversial issue, this regeneration process is believed to be caused by surfactant accumulation in the meniscus region (1). We show that modification of the relevant capillary drainage equation to account for Marangoni effects through a course-grained slip condition at the air-liquid interface produces exponents in better agreement with experimental findings. (1) V. A. Nierstrasz and G. Frens, JCIS 215, 28 (1999).

Experimental study of three-wave interactions among capillary-gravity surface waves

NASA Astrophysics Data System (ADS)

Haudin, Florence; Cazaubiel, Annette; Deike, Luc; Jamin, Timothée; Falcon, Eric; Berhanu, Michael

2016-04-01

In propagating wave systems, three- or four-wave resonant interactions constitute a classical nonlinear mechanism exchanging energy between the different scales. Here we investigate three-wave interactions for gravity-capillary surface waves in a closed laboratory tank. We generate two crossing wave trains and we study their interaction. Using two optical methods, a local one (laser doppler vibrometry) and a spatiotemporal one (diffusive light photography), a third wave of smaller amplitude is detected, verifying the three-wave resonance conditions in frequency and in wave number. Furthermore, by focusing on the stationary regime and by taking into account viscous dissipation, we directly estimate the growth rate of the resonant mode. The latter is then compared to the predictions of the weakly nonlinear triadic resonance interaction theory. The obtained results confirm qualitatively and extend previous experimental results obtained only for collinear wave trains. Finally, we discuss the relevance of three-wave interaction mechanisms in recent experiments studying gravity-capillary turbulence.

Experimental study of three-wave interactions among capillary-gravity surface waves.

PubMed

Haudin, Florence; Cazaubiel, Annette; Deike, Luc; Jamin, Timothée; Falcon, Eric; Berhanu, Michael

2016-04-01

In propagating wave systems, three- or four-wave resonant interactions constitute a classical nonlinear mechanism exchanging energy between the different scales. Here we investigate three-wave interactions for gravity-capillary surface waves in a closed laboratory tank. We generate two crossing wave trains and we study their interaction. Using two optical methods, a local one (laser doppler vibrometry) and a spatiotemporal one (diffusive light photography), a third wave of smaller amplitude is detected, verifying the three-wave resonance conditions in frequency and in wave number. Furthermore, by focusing on the stationary regime and by taking into account viscous dissipation, we directly estimate the growth rate of the resonant mode. The latter is then compared to the predictions of the weakly nonlinear triadic resonance interaction theory. The obtained results confirm qualitatively and extend previous experimental results obtained only for collinear wave trains. Finally, we discuss the relevance of three-wave interaction mechanisms in recent experiments studying gravity-capillary turbulence.

3D Printing by Multiphase Silicone/Water Capillary Inks.

PubMed

Roh, Sangchul; Parekh, Dishit P; Bharti, Bhuvnesh; Stoyanov, Simeon D; Velev, Orlin D

2017-08-01

3D printing of polymers is accomplished easily with thermoplastics as the extruded hot melt solidifies rapidly during the printing process. Printing with liquid polymer precursors is more challenging due to their longer curing times. One curable liquid polymer of specific interest is polydimethylsiloxane (PDMS). This study demonstrates a new efficient technique for 3D printing with PDMS by using a capillary suspension ink containing PDMS in the form of both precured microbeads and uncured liquid precursor, dispersed in water as continuous medium. The PDMS microbeads are held together in thixotropic granular paste by capillary attraction induced by the liquid precursor. These capillary suspensions possess high storage moduli and yield stresses that are needed for direct ink writing. They could be 3D printed and cured both in air and under water. The resulting PDMS structures are remarkably elastic, flexible, and extensible. As the ink is made of porous, biocompatible silicone that can be printed directly inside aqueous medium, it can be used in 3D printed biomedical products, or in applications such as direct printing of bioscaffolds on live tissue. This study demonstrates a number of examples using the high softness, elasticity, and resilience of these 3D printed structures. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microcrystallography using single-bounce monocapillary optics

PubMed Central

Gillilan, R. E.; Cook, M. J.; Cornaby, S. W.; Bilderback, D. H.

2010-01-01

X-ray microbeams have become increasingly valuable in protein crystallography. A number of synchrotron beamlines worldwide have adapted to handling smaller and more challenging samples by providing a combination of high-precision sample-positioning hardware, special visible-light optics for sample visualization, and small-diameter X-ray beams with low background scatter. Most commonly, X-ray microbeams with diameters ranging from 50 µm to 1 µm are produced by Kirkpatrick and Baez mirrors in combination with defining apertures and scatter guards. A simple alternative based on single-bounce glass monocapillary X-ray optics is presented. The basic capillary design considerations are discussed and a practical and robust implementation that capitalizes on existing beamline hardware is presented. A design for mounting the capillary is presented which eliminates parasitic scattering and reduces deformations of the optic to a degree suitable for use on next-generation X-ray sources. Comparison of diffraction data statistics for microcrystals using microbeam and conventional aperture-collimated beam shows that capillary-focused beam can deliver significant improvement. Statistics also confirm that the annular beam profile produced by the capillary optic does not impact data quality in an observable way. Examples are given of new structures recently solved using this technology. Single-bounce monocapillary optics can offer an attractive alternative for retrofitting existing beamlines for microcrystallography. PMID:20157276

Computation of three-phase capillary entry pressures and arc menisci configurations in pore geometries from 2D rock images: A combinatorial approach

NASA Astrophysics Data System (ADS)

Zhou, Yingfang; Helland, Johan Olav; Hatzignatiou, Dimitrios G.

2014-07-01

We present a semi-analytical, combinatorial approach to compute three-phase capillary entry pressures for gas invasion into pore throats with constant cross-sections of arbitrary shapes that are occupied by oil and/or water. For a specific set of three-phase capillary pressures, geometrically allowed gas/oil, oil/water and gas/water arc menisci are determined by moving two circles in opposite directions along the pore/solid boundary for each fluid pair such that the contact angle is defined at the front circular arcs. Intersections of the two circles determine the geometrically allowed arc menisci for each fluid pair. The resulting interfaces are combined systematically to allow for all geometrically possible three-phase configuration changes. The three-phase extension of the Mayer and Stowe - Princen method is adopted to calculate capillary entry pressures for all determined configuration candidates, from which the most favorable gas invasion configuration is determined. The model is validated by comparing computed three-phase capillary entry pressures and corresponding fluid configurations with analytical solutions in idealized triangular star-shaped pores. It is demonstrated that the model accounts for all scenarios that have been analyzed previously in these shapes. Finally, three-phase capillary entry pressures and associated fluid configurations are computed in throat cross-sections extracted from segmented SEM images of Bentheim sandstone. The computed gas/oil capillary entry pressures account for the expected dependence of oil/water capillary pressure in spreading and non-spreading fluid systems at the considered wetting conditions. Because these geometries are irregular and include constrictions, we introduce three-phase displacements that have not been identified previously in pore-network models that are based on idealized pore shapes. However, in the limited number of pore geometries considered in this work, we find that the favorable displacements are not generically different from those already encountered in network models previously, except that the size and shape of oil layers that are surrounded by gas and water are described more realistically. The significance of the results for describing oil connectivity in porous media accurately can only be evaluated by including throats with more complex cross-sections in three-phase pore-network models.

Probability modeling of the number of positive cores in a prostate cancer biopsy session, with applications.

PubMed

Serfling, Robert; Ogola, Gerald

2016-02-10

Among men, prostate cancer (CaP) is the most common newly diagnosed cancer and the second leading cause of death from cancer. A major issue of very large scale is avoiding both over-treatment and under-treatment of CaP cases. The central challenge is deciding clinical significance or insignificance when the CaP biopsy results are positive but only marginally so. A related concern is deciding how to increase the number of biopsy cores for larger prostates. As a foundation for improved choice of number of cores and improved interpretation of biopsy results, we develop a probability model for the number of positive cores found in a biopsy, given the total number of cores, the volumes of the tumor nodules, and - very importantly - the prostate volume. Also, three applications are carried out: guidelines for the number of cores as a function of prostate volume, decision rules for insignificant versus significant CaP using number of positive cores, and, using prior distributions on total tumor size, Bayesian posterior probabilities for insignificant CaP and posterior median CaP. The model-based results have generality of application, take prostate volume into account, and provide attractive tradeoffs of specificity versus sensitivity. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Experimental study of two-phase fluid flow in two different porosity types of sandstone by P-wave velocity and electrical Impedance measurement

NASA Astrophysics Data System (ADS)

Honda, H.; Mitani, Y.; Kitamura, K.; Ikemi, H.; Takaki, S.

2015-12-01

Carbon dioxide (CO2) capture and storage (CCS) is recently expected as the promising method to reduce greenhouse gas emissions. It is important to investigate CO2 behavior in the reservoir, to evaluate the safety and to account the stored CO2 volume. In this study, experimental investigation is conducted to discuss the relationships between injected fluid speed (Flow rate: FR) or capillary number (Ca) and non-wetting fluid flow by compressional wave velocity (Vp) and electrical impedance (Z). In the experiment, N2 and supercritical CO2 were injected into the two sandstones with different porosity (φ), Berea sandstone (φ: 18 %), and Ainoura sandstone (φ: 11.9 %). The dimension of the rock specimens is cored cylinder with a 35 mm diameter and 70 mm height. Experimental conditions are nearly same as the reservoir of deep underground (Confining pressure:15MPa, 40℃). Initial conditions of the specimen are brine (0.1wt%-KCl) saturated. Four piezo-electrical transducers (PZTs) are set on the each surface of the top, middle, lower of the specimen to monitor the CO2 bahavior by Vp. To measuring Z, we use for electrodes method with Ag-AgCl electrodes. Four electrodes are wounded around specimen on the both sides of PZTs. We measured the changes of these parameters with injecting N2, injected fluid speed (FR), the differential pore pressure (DP), N2 saturation (SN2), P-wave velocity (Vp) and electrical impedance (Z), respectively. We also estimated the Ca from measured FR. From these experimental results, there are no obvious Vp changes with increasing Ca, while Z measurement indicates clear and continuous increment. In regards to Vp, Vp reduced at the small FR (0.1 to 0.2 ml/min). As the Ca increases, Vp doesn't indicate large reduction. On the other hand, Z is more sensitive to change the fluid saturation than Vp. It is well-known that both of Vp and Z are the function of fluid saturation. Though, these experimental results are not consistent with previous studies. In this study, we will discuss this mismatch by using fluid mechanical theory and numerical simulation of two-phase fluid flow in porous geological medium based on experimental results of two different types of sandstone.

Apparent and microscopic dynamic contact angles in confined flows

NASA Astrophysics Data System (ADS)

Omori, Takeshi; Kajishima, Takeo

2017-11-01

An abundance of empirical correlations between a dynamic contact angle and a capillary number representing a translational velocity of a contact line have been provided for the last decades. The experimentally obtained dynamic contact angles are inevitably apparent contact angles but often undistinguished from microscopic contact angles formed right on the wall. As Bonn et al. ["Wetting and spreading," Rev. Mod. Phys. 81, 739-805 (2009)] pointed out, however, most of the experimental studies simply report values of angles recorded at some length scale which is quantitatively unknown. It is therefore hard to evaluate or judge the physical validity and the generality of the empirical correlations. The present study is an attempt to clear this clutter regarding the dynamic contact angle by measuring both the apparent and the microscopic dynamic contact angles from the identical data sets in a well-controlled manner, by means of numerical simulation. The numerical method was constructed so that it reproduced the fine details of the flow with a moving contact line predicted by molecular dynamics simulations [T. Qian, X. Wang, and P. Sheng, "Molecular hydrodynamics of the moving contact line in two-phase immiscible flows," Commun. Comput. Phys. 1, 1-52 (2006)]. We show that the microscopic contact angle as a function of the capillary number has the same form as Blake's molecular-kinetic model [T. Blake and J. Haynes, "Kinetics of liquid/liquid displacement," J. Colloid Interface Sci. 30, 421-423 (1969)], regardless of the way the flow is driven, the channel width, the mechanical properties of the receding fluid, and the value of the equilibrium contact angle under the conditions where the Reynolds and capillary numbers are small. We have also found that the apparent contact angle obtained by the arc-fitting of the interface behaves surprisingly universally as claimed in experimental studies in the literature [e.g., X. Li et al., "An experimental study on dynamic pore wettability," Chem. Eng. Sci. 104, 988-997 (2013)], although the angle deviates significantly from the microscopic contact angle. It leads to a practically important point that it suffices to measure arc-fitted contact angles to make formulae to predict flow rates in capillary tubes.

Quantitative assessment of macular contraction and vitreoretinal interface alterations in diabetic macular edema treated with intravitreal anti-VEGF injections.

PubMed

Cetin, Ebru Nevin; Demirtaş, Önder; Özbakış, Nihal Cesur; Pekel, Gökhan

2018-06-20

Macular contraction after anti-vascular endothelial growth factor (anti-VEGF) injections for diabetic macular edema (DME) was evaluated by documenting the displacement of macular capillary vessels and epiretinal membrane (ERM) formation. A total of 130 eyes were included in this retrospective study. The study group consisted of 63 eyes which had intravitreal anti-VEGF injections for DME, and the control group included 67 eyes without central DME. The study and the control groups were well balanced in terms of diabetes duration and HbA1c. The distances between the bifurcation of the macular capillary retinal vessels were measured, and ERM status was evaluated based on spectral-OCT findings on the initial and final visit. In the study group, the mean number of injections was 4.7 ± 2.6 (3-14). The mean follow-up time was 16.7 ± 7.8 months in the study group whereas it was 20.7 ± 10.9 months in the control group (p = 0.132). The change in distance measurements between the reference points on macular capillary vessels was significant in all lines except line c (p < 0.05 for lines a, b, d, e, and f) in the study group whereas it was significant in only line e in the control group (p = 0.007, paired samples test). However, when the change in macular thickness was accounted as a confounding factor, the change in distances between the references points from the initial visit to the final visit lost its significance (repeated measures ANCOVA, p > 0.05). During follow-up, the number of cases with ERM changed from 10 to 12 in the study group whereas it remained three in the control group. There was a displacement of macular capillary vessels which was associated with the change in macular thickness in eyes having anti-VEGF injections for DME. The number of ERM cases did not change significantly during the follow-up.

Capillary zone electrophoresis for analysis of phytochelatins and other thiol peptides in complex biological samples derivatized with monobromobimane.

PubMed

Perez-Rama, Mónica; Torres Vaamonde, Enrique; Abalde Alonso, Julio

2005-02-01

A new method to improve the analysis of phytochelatins and their precursors (cysteine, gamma-Glu-Cys, and glutathione) derivatized with monobromobimane (mBrB) in complex biological samples by capillary zone electrophoresis is described. The effects of the background electrolyte pH, concentration, and different organic additives (acetonitrile, methanol, and trifluoroethanol) on the separation were studied to achieve optimum resolution and number of theoretical plates of the analyzed compounds in the electropherograms. Optimum separation of the thiol peptides was obtained with 150 mM phosphate buffer at pH 1.60. Separation efficiency was improved when 2.5% v/v methanol was added to the background electrolyte. The electrophoretic conditions were 13 kV and capillary dimensions with 30 cm length from the inlet to the detector (38 cm total length) and 50 microm inner diameter. The injection was by pressure at 50 mbar for 17 s. Under these conditions, the separation between desglycyl-peptides and phytochelatins was also achieved. We also describe the optimum conditions for the derivatization of biological samples with mBrB to increase electrophoretic sensitivity and number of theoretical plates. The improved method was shown to be simple, reproducible, selective, and accurate in measuring thiol peptides in complex biological samples, the detection limit being 2.5 microM glutathione at a wavelength of 390 nm.

Self-Similar Taylor Cone Formation in Conducting Viscous Films: Computational Study of the Influence of Reynolds Number

NASA Astrophysics Data System (ADS)

Albertson, Theodore; Troian, Sandra

2017-11-01

Previous studies by Zubarev (2001) and Suvorov and Zubarev (2004) have shown that above a critical field strength, an ideal (inviscid) conducting fluid film will deform into a singular profile characterized by a conic cusp. The governing equations for the electrohydrodynamic response beneath the cusp admit self-similar solutions leading to so-called blow-up behavior in the Maxwell pressure, capillary pressure and kinetic energy density. The runaway behavior in these variables reflects divergence in time characterized by an exponent of -2/3. Here we extend the physical system to include viscous effects and conduct a computational study of the cusp region as a function of increasing electrical Reynolds number ReE . We employ a finite element, moving mesh algorithm to examine the behavior of the film shape, Maxwell pressure and capillary pressure upon approach to the blow-up event. Our study indicates that self-similarity establishes at relatively low ReE despite the presence of vorticity, which is localized to the cusp surface region. With increasing ReE , the period of self-similiarity extends further in time as the exponent changes from about -4/5 to the ideal value of -2/3, with slightly different values distinguishing the Maxwell and capillary stresses. T. Albertson gratefully acknowledges support from a NASA Space Technology Research Fellowship.

Nephrocalcinosis and Placental Findings in Neonatal Bartter Syndrome

PubMed Central

Maruyama, Hidehiko; Shinno, Yoko; Fujiwara, Kaori; Nakamura, Akie; Tajima, Toshihiro; Nakamura, Makoto; Kageyama, Misao

2012-01-01

Neonatal Bartter syndrome (NBS) is an inherited renal tubular disorder associated with hypokalemic alkalosis. Here we report a case of genetically diagnosed NBS. Polyhydramnios was noted at 26 weeks. A boy was born at 31 weeks and 1 day, weighed 1344 g, and had an Apgar score of 8/8. We initiated indomethacin (IND) at a dose of 0.2 mg/kg/d on day 31, and increased it to approximately 3 mg/kg/d. However, his urinary calcium (Ca) levels remained unchanged. At 4 months of age, nephrocalcinosis was detected by ultrasound. The placenta weighed 700 g (+2.7 standard deviations). Although the proportion of terminal villi was consistent with the gestational age, many of them exhibited poorly dilated capillaries. Hemosiderin pigment was seen throughout the amniochorionic connective tissue and along about 50% of the trophoblast basement membrane (TBM). Von Kossa stain revealed the corresponding area of mineralization along the TBM. In our opinion, urinary Ca levels were high and did not change after IND initiation, indicating that nephrocalcinosis may be inevitable. Enhanced inflow of maternal plasma through the basement membrane would cause Ca deposition, given that the same finding was obtained in the case with polyhydramnios. The same mechanism would also explain the hemosiderin pigment distribution. PMID:23943704

Rebamipide, an anti-ulcerative drug, inhibits induction of salivary dysfunction by benzodiazepines.

PubMed

Ogane, M; Okubo, M; Yoshikawa, M; Shinomiya, T; Tsukagoshi, E; Kawaguchi, M

2017-05-01

The purpose of this study was to determine whether rebamipide, an antistomach ulcer agent, ameliorated benzodiazepine-induced hyposalivation in rat parotid gland (PG) and submandibular gland (SMG). Saliva was collected from PG and SMG through a capillary cannula inserted into the parotid duct and sublingual papillae, respectively, every 15 min for 1 h after stimulation with pilocarpine dissolved in physiological saline and intraperitoneally administered at 1 mg kg -1 . Diazepam (DZP) was administered intraperitoneally at a dose of 0.2 mg kg -1 twice daily for 7 days. Rebamipide was administered at 10, 20, 30, or 100 mg kg -1 concomitantly with DZP to determine its effect on hyposalivation. The effect of rebamipide on movement of intracellular calcium ([Ca 2+ ]i) in isolated parotid acinar cells was analyzed using Fluo4, a fluorescent dye used to detect Ca 2+ . Repetitive administration of DZP decreased salivary secretion in PG and SMG. This inhibitory effect was weakened by administration of rebamipide. Prior administration of DZP (10 -6 M) significantly suppressed carbachol (10 -7 M)-induced increase in [Ca 2+ ]i. This inhibitory effect was ameliorated by combined use with rebamipide (5 × 10 -4 M). This findings suggest that rebamipide weakens the downregulatory effect of DZP on salivary secretion by preventing DZP-induced suppression of increase in [Ca 2+ ]i. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Single-Pixel Optical Fluctuation Analysis of Calcium Channel Function in Active Zones of Motor Nerve Terminals

PubMed Central

Luo, Fujun; Dittrich, Markus; Stiles, Joel R.; Meriney, Stephen D.

2011-01-01

We used high-resolution fluorescence imaging and single-pixel optical fluctuation analysis to estimate the opening probability of individual voltage-gated calcium (Ca2+) channels during an action potential and the number of such Ca2+ channels within active zones of frog neuromuscular junctions. Analysis revealed ~36 Ca2+ channels within each active zone, similar to the number of docked synaptic vesicles but far less than the total number of transmembrane particles reported based on freeze-fracture analysis (~200–250). The probability that each channel opened during an action potential was only ~0.2. These results suggest why each active zone averages only one quantal release event during every other action potential, despite a substantial number of docked vesicles. With sparse Ca2+ channels and low opening probability, triggering of fusion for each vesicle is primarily controlled by Ca2+ influx through individual Ca2+ channels. In contrast, the entire synapse is highly reliable because it contains hundreds of active zones. PMID:21813687

Taking a Closer Look--Continuous Glucose Monitoring in Non-Critically Ill Hospitalized Patients with Type 2 Diabetes Mellitus Under Basal-Bolus Insulin Therapy.

PubMed

Schaupp, Lukas; Donsa, Klaus; Neubauer, Katharina M; Mader, Julia K; Aberer, Felix; Höll, Bernhard; Spat, Stephan; Augustin, Thomas; Beck, Peter; Pieber, Thomas R; Plank, Johannes

2015-09-01

Inpatient glucose management is based on four daily capillary blood glucose (BG) measurements. The aim was to test the capability of continuous glucose monitoring (CGM) for assessing the clinical impact and safety of basal-bolus insulin therapy in non-critically ill hospitalized patients with type 2 diabetes mellitus (T2DM). Eighty-four patients with T2DM (age, 68±10 years; glycosylated hemoglobin, 72±28 mmol/mol; body mass index, 31±7 kg/m(2)) were treated with basal-bolus insulin. CGM was performed with the iPro(®)2 system (Medtronic MiniMed, Northridge, CA) and calibrated retrospectively. A remarkable consistency between CGM and BG measurements and therapy improvement was shown over the study period of 501 patient-days. The number of CGM and BG measurements (CGM/BG) in the range from 3.9-10 mmol/L increased from 67.7%/67.2% (on Day 1) to 77.5%/78.6% (on the last day) (P<0.04). The number of low glycemic episodes (3.3 to <3.9 mmol/L) during nighttime detected by CGM was 15-fold higher, and the number of episodes >13.9 mmol/L detected by CGM during night was 12.5-fold higher than the values from the BG measurements. Ninety-nine percent of data points were in the clinically accurate or acceptable Clarke Error Grid Zones A+B, and the relative numbers of correctly identified episodes of <3.9 and >13.9 mmol/L detected by CGM (sensitivity) were 47.3% and 81.5%, respectively. Our data exhibit a good agreement between overall CGM and BG measurements, but there were a high number of missed hypo- and hyperglycemic episodes with BG measurements, particularly during nighttime. Overall assessment of glycemic control using CGM is feasible, whereas the use of CGM for individualized therapy decisions needs further improvement.

Calcium environment in silicate and aluminosilicate glasses probed by ⁴³Ca MQMAS NMR experiments and MD-GIPAW calculations.

PubMed

Gambuzzi, Elisa; Pedone, Alfonso; Menziani, Maria Cristina; Angeli, Frédéric; Florian, Pierre; Charpentier, Thibault

2015-01-01

⁴³Ca MQMAS NMR spectra of three silica-based glasses in which Ca²⁺ ions play different structural roles have been collected and processed in order to extract the underlying NMR parameter distributions. The NMR parameters have been interpreted with the help of molecular dynamics simulations and DFT-GIPAW calculations. This synergetic experimental-computational approach has allowed us to investigate the Ca environment, to estimate Ca coordination numbers from MD-derived models, and to push further the discussion about ⁴³Ca NMR sensitivity to the first and second coordination spheres: ⁴³Ca δiso and Ca-O distance can be successfully correlated as a function of Ca coordination number. Copyright © 2015 Elsevier Inc. All rights reserved.

Uniform Laser Excitation And Detection In Capillary Array Electrophoresis System And Method.

DOEpatents

Li, Qingbo; Zhou, Songsan; Liu, Changsheng

2003-10-07

A capillary electrophoresis system comprises capillaries positioned in parallel to each other forming a plane. The capillaries are configured to allow samples to migrate. A light source is configured to illuminate the capillaries and the samples therein. This causes the samples to emit light. A lens is configured to receive the light emitted by the samples and positioned directly over a first group of the capillaries and obliquely over a second group of the capillaries. The light source is further configured to illuminate the second group of capillaries more than the first group of the capillaries such that amount of light received by the lens from the first group of capillaries is substantially identical to amount of light received from the second group of capillaries when an identical amount of the samples is migrating through the first and second group capillaries.

Capillary electrophoresis electrospray ionization mass spectrometry interface

DOEpatents

Smith, Richard D.; Severs, Joanne C.

1999-01-01

The present invention is an interface between a capillary electrophoresis separation capillary end and an electrospray ionization mass spectrometry emitter capillary end, for transporting an anolyte sample from a capillary electrophoresis separation capillary to a electrospray ionization mass spectrometry emitter capillary. The interface of the present invention has: (a) a charge transfer fitting enclosing both of the capillary electrophoresis capillary end and the electrospray ionization mass spectrometry emitter capillary end; (b) a reservoir containing an electrolyte surrounding the charge transfer fitting; and (c) an electrode immersed into the electrolyte, the electrode closing a capillary electrophoresis circuit and providing charge transfer across the charge transfer fitting while avoiding substantial bulk fluid transfer across the charge transfer fitting. Advantages of the present invention have been demonstrated as effective in providing high sensitivity and efficient analyses.

Capillary electrophoresis/mass spectrometry determination of inorganic ions using an ion spray-sheath flow interface.

PubMed

Huggins, T G; Henion, J D

1993-01-01

The determination of inorganic cations and anions by capillary electrophoresis/mass spectrometry (CE/MS) is reported using an ion spray-sheath flow interface coupling. A twelve-component synthetic mixture of cations which included the positive ions of K, Ba, Ca, Mn, Cd, Co, Pb, Cr, Ni, Zn, Ag, and Cu was loaded into the capillary column at levels ranging from 30 to 300 pg, separated by CE, and detected by indirect UV and in the full-scan (m/z 35-450) positive ion CE/MS mode using an aqueous buffer containing 30 mM creatinine and 8 mM alpha-hydroxyisobutyric acid, pH 4.8. Creatinine forms adducts with the cations which are observed in the gas phase and requires rather high (120 electron volts) declustering energy to dissociate. This produces a reduction in charge state to form the free, singly charged, inorganic cations which are observed in the mass spectra. CE/MS analysis of an aqueous acidic extract of used aircraft engine oil revealed high levels of lead as well as lower levels of chromium and nickel. CE-indirect UV analysis of a synthetic mixture containing 300 pg each of 11 inorganic ions, which included the anions of Br, Cl, NO2, NO3, S2O3, N3, SCN, SO4, SeO4, oxalate, and MoO4, is shown. The running buffer which affected this separation contained 5 mM ammonium dichromate, 10 mM ammonium acetate, and 20 mM diethylenetriamine at pH 9.3. Although indirect UV detection revealed good separation of these anions, CE/MS analysis of this mixture was complicated by interfering ion current signals from the cluster ions formed by the interaction between the additives and the analytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular and functional characterization of riboflavin specific transport system in rat brain capillary endothelial cells.

PubMed

Patel, Mitesh; Vadlapatla, Ramya Krishna; Pal, Dhananjay; Mitra, Ashim K

2012-08-15

Riboflavin is an important water soluble vitamin (B2) required for metabolic reactions, normal cellular growth, differentiation and function. Mammalian brain cells cannot synthesize riboflavin and must import from systemic circulation. However, the uptake mechanism, cellular translocation and intracellular trafficking of riboflavin in brain capillary endothelial cells are poorly understood. The primary objective of this study is to investigate the existence of a riboflavin-specific transport system and delineate the uptake and intracellular regulation of riboflavin in immortalized rat brain capillary endothelial cells (RBE4). The uptake of [3H]-riboflavin is sodium, temperature and energy dependent but pH independent. [3H]-Riboflavin uptake is saturable with K(m) and V(max) values of 19 ± 3 μM and 0.235 ± 0.012 pmol/min/mg protein, respectively. The uptake process is inhibited by unlabelled structural analogs (lumiflavin, lumichrome) but not by structurally unrelated vitamins. Ca(++)/calmodulin and protein kinase A (PKA) pathways are found to play an important role in the intracellular regulation of [3H]-riboflavin. Apical and baso-lateral uptake of [3H]-riboflavin clearly indicates that a riboflavin specific transport system is predominantly localized on the apical side of RBE4 cells. A 628 bp band corresponding to a riboflavin transporter is revealed in RT-PCR analysis. These findings, for the first time report the existence of a specialized and high affinity transport system for riboflavin in RBE4 cells. The blood-brain barrier (BBB) is a major obstacle limiting drug transport inside the brain as it regulates drug permeation from systemic circulation. This transporter can be utilized for targeted delivery in enhancing brain permeation of highly potent drugs on systemic administration. Copyright © 2012 Elsevier B.V. All rights reserved.

76 FR 28818 - Division of Federal Employees' Compensation Proposed Renewal of the Existing Collection; Comment...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-18

... Audiological Examination (CA-1087); Referral for a Complete Audiologic and Otologic Examination (CA-1331... Number: CA-7; CA-16; CA-17; CA-20; CA-1090; CA-1305; CA- 1087; CA-1331; CA-1332; OWCP-5a; OWCP-5b; and... 10 min 225 38 CA-1305 20 min 130 43 CA-1331/CA-1087 5 min 1,108 92 CA-1332 30 min 10 5 OWCP-5's 15...

Ultrastructural alteration of mouse lung by prolonged exposure to mixtures of helium and oxygen

NASA Technical Reports Server (NTRS)

Harrison, G. A.; Solomon, J. D.

1975-01-01

Observed changes consist mainly of blebbing of capillary endothelium and alveolar epithelium, which is quite possibly indicative of cellular edema; also, there can be observed highly-convoluted basement membrane, alveolar debris, and increased numbers of platelets.

The relationship of photoreceptor degeneration to retinal vascular development and loss in mutant rhodopsin transgenic and RCS rats.

PubMed

Pennesi, Mark E; Nishikawa, Shimpei; Matthes, Michael T; Yasumura, Douglas; LaVail, Matthew M

2008-12-01

The early loss of photoreceptors in some retinal degenerations in mice has been shown to have a profound effect on vascular development of the retina. To better characterize this relationship, we have examined the formation of retinal blood vessels during the first month of life in 8 lines of transgenic rats with different ages of onset and rates of photoreceptor cell loss mediated by the expression of mutant rhodopsin (P23H and S334ter). The number of capillary profiles in the superficial plexus (SP) and deep capillary plexus (DCP) of the retina were quantified in retinal sections taken at postnatal day (P) 8, 10, 12, 15 and 30. In normal wild-type rats, the SP and DCP had mostly established mature, adult patterns by P15, as previously shown. In the transgenic rats, the loss of photoreceptors had relatively little effect on the SP. By contrast, the loss of photoreceptors during vascular development had a major impact on the DCP. In the two lines with early and most rapid photoreceptor loss, S334ter-7 and S334ter-3, where about 90% and 65%, respectively, of the photoreceptors were already lost by P15, the DCP either failed to form (S334ter-7) or the number of capillary profiles was less than 7% of controls (S334ter-3). In lines where almost all photoreceptors were still present at P15 (S334ter-4, S334ter-9, P23H-2 and P23H-3), the number of profiles in the DCP were the same as in wild-type controls at P30. In two lines with an intermediate rate of degeneration (S334ter-5 and P23H-1), where only about 25% of the photoreceptors were lost by P15, there was an intermediate number of vascular profiles in the DCP at P30. Thus, a very close relationship between the number of photoreceptors and vessel profiles in the DCP during its development exists in the transgenic rats, and the loss of photoreceptors results in the failure or inhibition of the DCP to develop. Several mechanisms may explain this relationship including changes in the level of physiological oxygen tension or alteration in the release of angiogenic factors that normally drive vessel development. Analysis of older transgenic retinas up to 1 year of age revealed that (1) vascular profiles are lost from the DCP in essentially all lines once fewer than about 30-33% of photoreceptors remain; (2) in those lines where the DCP essentially did not develop (S334ter-7 and S334ter-3), the effect of photoreceptor absence was permanent, and there was no late vascularization of the DCP; (3) the number of capillary profiles in the SP remained no different from controls in any of the lines, despite long-standing loss of photoreceptors; and (4) neovascularization of the RPE by retinal capillaries occurred with a latency of 60-180 days after the loss of photoreceptors, except in S334ter-7 rats, where neovascularization essentially did not occur. Analysis of RCS rats was carried out for comparison.

Influence of Peripheral Architecture on the Properties of Aryl Polyhedral Oligomeric Silsesquioxanes

DTIC Science & Technology

2012-03-28

8. PERFORMING ORGANIZATION REPORT NUMBER Air Force Research Laboratory (AFMC) AFRL/RZSM 9 Antares Road Edwards AFB CA 93524-7401 9...SPONSOR/MONITOR’S 5 Pollux Drive NUMBER(S) Edwards AFB CA 93524-7048 AFRL-RZ-ED-VG-2012-086 12. DISTRIBUTION / AVAILABILITY STATEMENT...National Meeting, San Diego, CA , 25-29 March 2012 and publication in Polymer Preprints, March 25, 2012. 14. ABSTRACT POSS compounds with non

Mississippi CaP HBCU Undergraduate Research Training Program

DTIC Science & Technology

2017-11-01

AWARD NUMBER: W81XWH-14-1-0151 TITLE: Mississippi CaP HBCU Undergraduate Research Training Program PRINCIPAL INVESTIGATOR: Christian Gomez...Final PREPARED FOR: U.S. Army Medical Research and Materiel Command Fort Detrick, Maryland 21702-5012 DISTRIBUTION STATEMENT: Approved for...2017 4. TITLE AND SUBTITLE Mississippi CaP HBCU Undergraduate Research Training Program 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-14-1-0151 5c

ESTCP Live Site Demonstrations Former Camp Beale, Marysville, CA

DTIC Science & Technology

2011-08-23

ESTCP Live Site Demonstrations Former Camp Beale Marysville, CA ESTCP MR-201165 Demonstration Data Report Former Camp Beale...with a collection of information if it does not display a currently valid OMB control number. 1. REPORT DATE AUG 2011 2 . REPORT TYPE N/A 3. DATES...COVERED - 4. TITLE AND SUBTITLE ESTCP Live Site Demonstrations Former Camp Beale Marysville, CA 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c

Universal Behavior of the Initial Stage of Drop Impact

NASA Astrophysics Data System (ADS)

Klaseboer, Evert; Manica, Rogerio; Chan, Derek Y. C.

2014-11-01

During the early stages of the impact of a drop on a solid surface, pressure builds up in the intervening thin lubricating air layer and deforms the drop. The extent of the characteristic deformation is determined by the competition between capillary, gravitational, and inertial forces that has been encapsulated in a simple analytic scaling law. For millimetric drops, variations of the observed deformation with impact velocity V exhibit a maximum defined by the Weber and Eötvös numbers: We =1 +Eo . The deformation scales as V1 /2 at the low-velocity capillary regime and as V-1 /2 at the high-velocity inertia regime, in excellent agreement with a variety of experimental systems.

Stability of Capillary Surfaces in Rectangular Containers: The Right Square Cylinder

NASA Technical Reports Server (NTRS)

Weislogel, M. M.; Hsieh, K. C.

1998-01-01

The linearized governing equations for an ideal fluid are presented for numerical analysis for the stability of free capillary surfaces in rectangular containers against unfavorable disturbances (accelerations,i.e. Rayleigh-Taylor instability). The equations are solved for the case of the right square cylinder. The results are expressed graphically in term of a critical Bond number as a function of system contact angle. A critical wetting phenomena in the corners is shown to significantly alter the region of stability for such containers in contrast to simpler geometries such as the right circular cylinder or the infinite rectangular slot. Such computational results provide additional constraints for the design of fluids systems for space-based applications.

Portable, lightweight, low power, ion chromatographic system with open tubular capillary columns.

PubMed

Kiplagat, Isaac K; Kubán, Petr; Pelcová, Pavlína; Kubán, Vlastimil

2010-07-30

Basic operation principles of a lightweight, low power, low cost, portable ion chromatograph utilizing open tubular ion chromatography in capillary columns coated with multi-layer polymeric stationary phases are demonstrated. A minimalistic configuration of a portable IC instrument was developed that does not require any chromatographic eluent delivery system, nor sample injection device as it uses gravity-based eluent flow and hydrodynamic sample injection adopted from capillary electrophoresis. As a detection device, an inexpensive commercially available capacitance sensor is used that has been shown to be a suitable substitute for contactless conductivity detection in capillary separation systems. The built-in temperature sensor allows for baseline drift correction typically encountered in conductivity/capacitance measurements without thermostating device. The whole instrument does not require any power supply for its operation, except the detection and data acquisition part that is provided by a USB port of a Netbook computer. It is extremely lightweight, its total weight including the Netbook computer is less than 2.5kg and it can be continuously operated for more than 8h. Several parameters of the instrument, such as detection cell design, eluent delivery systems and data treatment were optimized as well as the composition of eluent for non-suppressed ion chromatographic analysis of common inorganic cations (Na(+), NH(4)(+), K(+), Cs(+), Ca(2+), Mg(2+), transition metals). Low conductivity eluents based on weakly complexing organic acids such as tartaric, oxalic or pyridine-2,6-dicarboxylic acids were used with contactless capacitance detection for simultaneous separation of mono- and divalent cations. Separation of Na(+) and NH(4)(+) cations was optimized by addition of 18-crown-6 to the eluent. The best separation of 6 metal cations commonly present in various environmental samples was accomplished in less than 30min using a 1.75mM pyridine-2,6-dicarboxylic acid and 3mM 18-crown-6 eluent with excellent repeatability (below 2%) and detection limits in the low micromolar range. The analysis of field samples is demonstrated; the concentrations of common inorganic cations in river water, mineral water and snow samples were determined.

Functional expression of P2X4 receptor in capillary endothelial cells of the cochlear spiral ligament and its role in regulating the capillary diameter.

PubMed

Wu, T; Dai, M; Shi, X R; Jiang, Z G; Nuttall, A L

2011-07-01

The cochlear lateral wall generates the endocochlear potential (EP), which creates a driving force for the hair cell transduction current and is essential for normal hearing. Blood flow at the cochlear lateral wall is critically important for maintaining the EP. The vulnerability of the EP to hypoxia suggests that the blood flow in the cochlear lateral wall is dynamically and precisely regulated to meet the changing metabolic needs of the cochlear lateral wall. It has been reported that ATP, an important extracellular signaling molecule, plays an essential role in regulating cochlear blood flow. However, the cellular mechanism underlying ATP-induced regional blood flow changes has not been investigated. In the current study, we demonstrate that 1) the P2X4 receptor is expressed in endothelial cells (ECs) of spiral ligament (SL) capillaries. 2) ATP elicits a characteristic current through P2X4 on ECs in a dose-dependent manner (EC(50) = 0.16 mM). The ATP current has a reversal potential at ∼0 mV; is inhibited by 5-(3-bromophenyl)-1,3-dihydro-2H-benzofuro[3,2-e]-1,4-diazepin-2-one (5-BDBD), LaCl(3), pyridoxal phosphate-6-azo(benzene-2,4-disulfonic acid) tetrasodium salt hydrate (PPADS), and extracellular acidosis; and is less sensitive to α,β-methyleneadenosine 5'-triphosphate (α,β-MeATP) and 2'- and 3'-O-(4-benzoyl-benzoyl) adenosine 5'-triphosphate (BzATP). 3) ATP elicits a transient increase of intracellular Ca(2+) in ECs. 4) In accordance with the above in vitro findings, perilymphatic ATP (1 mM) caused dilation in SL capillaries in vivo by 11.5%. N(ω)-nitro-l-arginine methyl ester hydrochloride (l-NAME), a nonselective inhibitor of nitric oxide synthase, or 5-BDBD, the specific P2X4 inhibitor, significantly blocked the dilation. These findings support our hypothesis that extracellular ATP regulates cochlear lateral blood flow through P2X4 activation in ECs.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Hongwu; Guo, Xiaofeng; Bai, Jianming

As an accessory mineral in marine evaporites, polyhalite, K 2MgCa 2(SO 4) 4·2H 2O, coexists with halite (NaCl) in salt formations, which have been considered as potential repositories for permanent storage of high-level nuclear wastes. However, because of the heat generated by radioactive decays in the wastes, polyhalite may dehydrate, and the released water will dissolve its neighboring salt, potentially affecting the repository integrity. Thus, studying the thermal behavior of polyhalite is important. In this paper, a polyhalite sample containing a small amount of halite was collected from the Salado formation at the WIPP site in Carlsbad, New Mexico. Tomore » determine its thermal behavior, in situ high-temperature synchrotron X-ray diffraction was conducted from room temperature to 1066 K with the sample powders sealed in a silica-glass capillary. At about 506 K, polyhalite started to decompose into water vapor, anhydrite (CaSO 4) and two langbeinite-type phases, K 2Ca x Mg 2-x (SO 4) 3, with different Ca/Mg ratios. XRD peaks of the minor halite disappeared, presumably due to its dissolution by water vapor. With further increasing temperature, the two langbeinite solid solution phases displayed complex variations in crystallinity, composition and their molar ratio and then were combined into the single-phase triple salt, K 2CaMg(SO 4) 3, at ~919 K. Rietveld analyses of the XRD data allowed determination of structural parameters of polyhalite and its decomposed anhydrite and langbeinite phases as a function of temperature. Finally, from the results, the thermal expansion coefficients of these phases have been derived, and the structural mechanisms of their thermal behavior been discussed.« less

PIK3CA-related overgrowth spectrum (PROS): diagnostic and testing eligibility criteria, differential diagnosis, and evaluation.

PubMed

Keppler-Noreuil, Kim M; Rios, Jonathan J; Parker, Victoria E R; Semple, Robert K; Lindhurst, Marjorie J; Sapp, Julie C; Alomari, Ahmad; Ezaki, Marybeth; Dobyns, William; Biesecker, Leslie G

2015-02-01

Somatic activating mutations in the phosphatidylinositol-3-kinase/AKT/mTOR pathway underlie heterogeneous segmental overgrowth phenotypes. Because of the extreme differences among patients, we sought to characterize the phenotypic spectrum associated with different genotypes and mutation burdens, including a better understanding of associated complications and natural history. Historically, the clinical diagnoses in patients with PIK3CA activating mutations have included Fibroadipose hyperplasia or Overgrowth (FAO), Hemihyperplasia Multiple Lipomatosis (HHML), Congenital Lipomatous Overgrowth, Vascular Malformations, Epidermal Nevi, Scoliosis/Skeletal and Spinal (CLOVES) syndrome, macrodactyly, Fibroadipose Infiltrating Lipomatosis, and the related megalencephaly syndromes, Megalencephaly-Capillary Malformation (MCAP or M-CM) and Dysplastic Megalencephaly (DMEG). A workshop was convened at the National Institutes of Health (NIH) to discuss and develop a consensus document regarding diagnosis and treatment of patients with PIK3CA-associated somatic overgrowth disorders. Participants in the workshop included a group of researchers from several institutions who have been studying these disorders and have published their findings, as well as representatives from patient-advocacy and support groups. The umbrella term of "PIK3CA-Related Overgrowth Spectrum (PROS)" was agreed upon to encompass both the known and emerging clinical entities associated with somatic PIK3CA mutations including, macrodactyly, FAO, HHML, CLOVES, and related megalencephaly conditions. Key clinical diagnostic features and criteria for testing were proposed, and testing approaches summarized. Preliminary recommendations for a uniform approach to assessment of overgrowth and molecular diagnostic testing were determined. Future areas to address include the surgical management of overgrowth tissue and vascular anomalies, the optimal approach to thrombosis risk, and the testing of potential pharmacologic therapies. © 2014 Wiley Periodicals, Inc.

PIK3CA-Related Overgrowth Spectrum (PROS): Diagnostic and Testing Eligibility Criteria, Differential Diagnosis, and Evaluation

PubMed Central

Keppler-Noreuil, Kim M.; Rios, Jonathan J.; Parker, Victoria E.R.; Semple, Robert K.; Lindhurst, Marjorie J.; Sapp, Julie C.; Alomari, Ahmad; Ezaki, Marybeth; Dobyns, William; Biesecker, Leslie G.

2015-01-01

Somatic activating mutations in the phosphatidylinositol-3-kinase/AKT/mTOR pathway underlie heterogeneous segmental overgrowth phenotypes. Because of the extreme differences among patients, we sought to characterize the phenotypic spectrum associated with different genotypes and mutation burdens, including a better understanding of associated complications and natural history. Historically, the clinical diagnoses in patients with PIK3CA activating mutations have included Fibroadipose hyperplasia or Overgrowth (FAO), Hemihyperplasia Multiple Lipomatosis (HHML), Congenital Lipomatous Overgrowth, Vascular Malformations, Epidermal Nevi, Scoliosis/Skeletal and Spinal (CLOVES) syndrome, macrodactyly, Fibroadipose Infiltrating Lipomatosis, and the related megalencephaly syndromes, Megalencephaly-Capillary Malformation (MCAP or M-CM) and Dysplastic Megalencephaly (DMEG). A workshop was convened at the National Institutes of Health (NIH) to discuss and develop a consensus document regarding diagnosis and treatment of patients with PIK3CA-associated somatic overgrowth disorders. Participants in the workshop included a group of researchers from several institutions who have been studying these disorders and have published their findings, as well as representatives from patient-advocacy and support groups. The umbrella term of “PIK3CA-Related Overgrowth Spectrum (PROS)” was agreed upon to encompass both the known and emerging clinical entities associated with somatic PIK3CA mutations including, macrodactyly, FAO, HHML, CLOVES, and related megalencephaly conditions. Key clinical diagnostic features and criteria for testing were proposed, and testing approaches summarized. Preliminary recommendations for a uniform approach to assessment of overgrowth and molecular diagnostic testing were determined. Future areas to address include the surgical management of overgrowth tissue and vascular anomalies, the optimal approach to thrombosis risk, and the testing of potential pharmacologic therapies. PMID:25557259

Thermal behavior of polyhalite: a high-temperature synchrotron XRD study

DOE PAGES

Xu, Hongwu; Guo, Xiaofeng; Bai, Jianming

2016-09-17

As an accessory mineral in marine evaporites, polyhalite, K 2MgCa 2(SO 4) 4·2H 2O, coexists with halite (NaCl) in salt formations, which have been considered as potential repositories for permanent storage of high-level nuclear wastes. However, because of the heat generated by radioactive decays in the wastes, polyhalite may dehydrate, and the released water will dissolve its neighboring salt, potentially affecting the repository integrity. Thus, studying the thermal behavior of polyhalite is important. In this paper, a polyhalite sample containing a small amount of halite was collected from the Salado formation at the WIPP site in Carlsbad, New Mexico. Tomore » determine its thermal behavior, in situ high-temperature synchrotron X-ray diffraction was conducted from room temperature to 1066 K with the sample powders sealed in a silica-glass capillary. At about 506 K, polyhalite started to decompose into water vapor, anhydrite (CaSO 4) and two langbeinite-type phases, K 2Ca x Mg 2-x (SO 4) 3, with different Ca/Mg ratios. XRD peaks of the minor halite disappeared, presumably due to its dissolution by water vapor. With further increasing temperature, the two langbeinite solid solution phases displayed complex variations in crystallinity, composition and their molar ratio and then were combined into the single-phase triple salt, K 2CaMg(SO 4) 3, at ~919 K. Rietveld analyses of the XRD data allowed determination of structural parameters of polyhalite and its decomposed anhydrite and langbeinite phases as a function of temperature. Finally, from the results, the thermal expansion coefficients of these phases have been derived, and the structural mechanisms of their thermal behavior been discussed.« less

The sow endometrium at different stages of the oestrous cycle: studies on morphological changes and infiltration by cells of the immune system.

PubMed

Kaeoket, K; Persson, E; Dalin, A M

2001-01-31

The aim of this study was to investigate the distribution of leukocytes and the morphological changes of the sow endometrium throughout the oestrous cycle. Fifteen crossbred multiparous sows (Swedish Landrace x Swedish Yorkshire), with an average parity number of 3.4 +/- 0.7 (mean +/- S.D.) were used. Blood samples were collected from the jugular vein 1h before slaughter for analyses of oestradiol-17beta and progesterone levels. Uterine samples from the mesometrial side of both horns, taken immediately after slaughter at late dioestrus, prooestrus, oestrus, early dioestrus and dioestrus, were fixed, embedded in plastic resin and stained with toluidine blue. The surface and glandular epithelium as well as subepithelial and glandular connective tissue layers were examined by light microscopy. The significantly highest surface and the glandular epithelium were observed at oestrus and dioestrus, respectively. The largest number of capillaries (underneath the surface epithelium) was found at oestrus. In the surface epithelium, the largest number of intraepithelial lymphocytes (IELs, round nucleus) was found at early dioestrus. The largest number of lymphocytes and macrophages within the glandular epithelium were found at early dioestrus and oestrus, respectively. In the subepithelial connective tissue layer, the most common type of leukocytes during all stages was the lymphocyte. The largest numbers of lymphocytes and neutrophils were found at oestrus while the largest number of eosinophils was found at dioestrus. The dominating cells of the immune system in the connective tissue of the glandular layer were lymphocytes and macrophages. The significantly largest numbers of lymphocytes and plasma cells were found at early dioestrus and dioestrus, respectively. The number of lymphocytes in the connective tissue of the glandular layer and the number of plasma cells in the subepithelial layer were positively correlated with the plasma level of progesterone (P < or = 0.05). The numbers of capillaries and neutrophils in the subepithelial layer underneath the surface epithelium as well as the number of macrophages in both surface and glandular epithelium were positively correlated with the plasma level of oestradiol-17beta (P < or = 0.05). In conclusion, the present study showed a variation in the infiltration and distribution of lymphocytes, neutrophils, eosinophils, macrophages, mast cells and plasma cells in the sow endometrium during different stages of the oestrous cycle. Also morphological parameters (e.g. height of surface and glandular epithelium, capillaries density and degree of oedema) varied throughout the oestrous cycle.

Corrigendum to "The sow endometrium at different stages of the oestrus cycle: studies on morphological changes and infiltration by cells of the immune system." [Anim. Reprod. Sci. 65 (2001) 95-114].

PubMed

Kaeoket, K; Persson, E; Dalin, A-M

2002-09-16

The aim of this study was to investigate the distribution of leukocytes and the morphological changes of the sow endometrium throughout the oestrous cycle. Fifteen crossbred multiparous sows (Swedish Landrace x Swedish Yorkshire), with an average parity number of 3.4+/-0.7 (mean+/-S.D.) were used. Blood samples were collected from the jugular vein 1 h before slaughter for analyses of oestradiol-17beta and progesterone levels. Uterine samples from the mesometrial side of both horns, taken immediately after slaughter at late dioestrus, prooestrus, oestrus, early dioestrus and dioestrus, were fixed, embedded in plastic resin and stained with toluidine blue. The surface and glandular epithelium as well as subepithelial and glandular connective tissue layers were examined by light microscopy (LM). The significantly highest surface and the glandular epithelium were observed at oestrus and dioestrus, respectively. The largest number of capillaries (underneath the surface epithelium) was found at oestrus. In the surface epithelium, the largest number of intraepithelial lymphocytes (IELs, round nucleus) was found at early dioestrus. The largest number of lymphocytes and macrophages within the glandular epithelium were found at early dioestrus and oestrus, respectively. In the subepithelial connective tissue layer, the most common type of leukocytes during all stages was the lymphocyte. The largest numbers of lymphocytes and neutrophils were found at oestrus while the largest number of eosinophils was found at dioestrus. The dominating cells of the immune system in the connective tissue of the glandular layer were lymphocytes and macrophages. The significantly largest numbers of lymphocytes and plasma cells were found at early dioestrus and dioestrus, respectively. The number of lymphocytes in the connective tissue of the glandular layer and the number of plasma cells in the subepithelial layer were positively correlated with the plasma level of progesterone (P < or = 0.05). The numbers of capillaries and neutrophils in the subepithelial layer underneath the surface epithelium as well as the number of macrophages in both surface and glandular epithelium were positively correlated with the plasma level of oestradiol-17beta (P < or = 0.05). In conclusion, the present study showed a variation om the infiltration and distrobution of lymphocytes, neutrophils, eosinophils, macrophages, mast cells, and plasma cells in the sow endometrium during different stages of the oestrous cycle. Also morphological parameters (e.g. height of surface and glandular epithelium, capillaries density and degree of oedema) varied throughout the oestrous cycle. Copyright 2002 Elsevier Science B.V.

Detachable strong cation exchange monolith, integrated with capillary zone electrophoresis and coupled with pH gradient elution, produces improved sensitivity and numbers of peptide identifications during bottom-up analysis of complex proteomes.

PubMed

Zhang, Zhenbin; Yan, Xiaojing; Sun, Liangliang; Zhu, Guijie; Dovichi, Norman J

2015-04-21

A detachable sulfonate-silica hybrid strong cation-exchange monolith was synthesized in a fused silica capillary, and used for solid phase extraction with online pH gradient elution during capillary zone electrophoresis-tandem mass spectrometry (CZE-MS/MS) proteomic analysis. Tryptic digests were prepared in 50 mM formic acid and loaded onto the strong cation-exchange monolith. Fractions were eluted using a series of buffers with lower concentration but higher pH values than the 50 mM formic acid background electrolyte. This combination of elution and background electrolytes results in both sample stacking and formation of a dynamic pH junction and allows use of relatively large elution buffer volumes while maintaining reasonable peak efficiency and resolution. A series of five pH bumps were applied to elute E. coli tryptic peptides from the monolith, followed by analysis using CZE coupled to an LTQ-Orbitrap Velos mass spectrometer; 799 protein groups and 3381 peptides were identified from 50 ng of the digest in a 2.5 h analysis, which approaches the identification rate for this organism that was obtained with an Orbitrap Fusion. We attribute the improved numbers of peptide and protein identifications to the efficient fractionation by the online pH gradient elution, which decreased the complexity of the sample in each elution step and improved the signal intensity of low abundance peptides. We also performed a comparative analysis using a nanoACQUITY UltraPerformance LCH system. Similar numbers of protein and peptide identifications were produced by the two methods. Protein identifications showed significant overlap between the two methods, whereas peptide identifications were complementary.

Observations of the Dynamic Connectivity of the Non-Wetting Phase During Steady State Flow at the Pore Scale Using 3D X-ray Microtomography

NASA Astrophysics Data System (ADS)

Reynolds, C. A.; Menke, H. P.; Blunt, M. J.; Krevor, S. C.

2015-12-01

We observe a new type of non-wetting phase flow using time-resolved pore scale imaging. The traditional conceptual model of drainage involves a non-wetting phase invading a porous medium saturated with a wetting phase as either a fixed, connected flow path through the centres of pores or as discrete ganglia which move individually through the pore space, depending on the capillary number. We observe a new type of flow behaviour at low capillary number in which the flow of the non-wetting phase occurs through networks of persistent ganglia that occupy the large pores but continuously rearrange their connectivity (Figure 1). Disconnections and reconnections occur randomly to provide short-lived pseudo-steady state flow paths between pores. This process is distinctly different to the notion of flowing ganglia which coalesce and break-up. The size distribution of ganglia is dependent on capillary number. Experiments were performed by co-injecting N2and 25 wt% KI brine into a Bentheimer sandstone core (4mm diameter, 35mm length) at 50°C and 10 MPa. Drainage was performed at three flow rates (0.04, 0.3 and 1 ml/min) at a constant fractional flow of 0.5 and the variation in ganglia populations and connectivity observed. We obtained images of the pore space during steady state flow with a time resolution of 43 s over 1-2 hours. Experiments were performed at the Diamond Light Source synchrotron. Figure 1. The position of N2 in the pore space during steady state flow is summed over 40 time steps. White indicates that N2 occupies the space over >38 time steps and red <5 time steps.

Correlation of macro and micro cardiovascular function during weightlessness and simulated weightlessness

NASA Technical Reports Server (NTRS)

Hutchins, P. M.; Marshburn, T. H.; Smith, T. L.; Osborne, S. W.; Lynch, C. D.; Moultsby, S. J.

1988-01-01

The investigation of cardiovascular function necessarily involves a consideration of the exchange of substances at the capillary. If cardiovascular function is compromised or in any way altered during exposure to zero gravity in space, then it stands to reason that microvascular function is also modified. We have shown that an increase in cardiac output similar to that reported during simulated weightlessness is associated with a doubling of the number of post-capillary venules and a reduction in the number of arterioles by 35%. If the weightlessness of space travel produces similar changes in cardiopulmonary volume and cardiac output, a reasonable expectation is that astronauts will undergo venous neovascularization. We have developed an animal model in which to correlate microvascular and systemic cardiovascular function. The microcirculatory preparation consists of a lightweight, thermo-neutral chamber implanted around intact skeletal muscle on the back of a rat. Using this technique, the performed microvasculature of the cutaneous maximus muscle may be observed in the conscious, unanesthetized animal. Microcirculatory variables which may be obtained include venular and arteriolar numbers, lengths and diameters, single vessel flow velocities, vasomotion, capillary hematocrit anastomoses and orders of branching. Systemic hemodynamic monitoring of cardiac output by electromagnetic flowmetry, and arterial and venous pressures allows correlation of macro- and microcirculatory changes at the same time, in the same animal. Observed and calculated hemodynamic variables also include pulse pressure, heart rate, stroke volume, total peripheral resistance, aortic compliance, minute work, peak aortic flow velocity and systolic time interval. In this manner, an integrated assessment of total cardiovascular function may be obtained in the same animal without the complicating influence of anesthetics.

Capillary instability of periodic polymer structures: Influence of viscosity, substrate confinement and local curvature

NASA Astrophysics Data System (ADS)

Zhang, Zheng; Ding, Yifu

2015-03-01

NMR spectrum and spin-lattice relaxation time(T1) of CaF2 thin film samples deposited on a silicon cantilever tip were obtained by magnetic resonance force microscopy(MRFM). Thickness of the thin films were 50nm and 150nm. In order to measure T1, a cyclic adiabatic inversion method was used with periodic phase inversion. A comparison of the bulk and two thin films showed that T1 becomes shorter as the film thickness decreases. To make the comparison as accurate as possible, all three samples were loaded onto different beams of a multi-cantilever array and measured in the same experimental conditions such as temperature and magnetic field.

Cerebral amyloid angiopathy, blood-brain barrier disruption and amyloid accumulation in SAMP8 mice.

PubMed

del Valle, Jaume; Duran-Vilaregut, Joaquim; Manich, Gemma; Pallàs, Mercè; Camins, Antoni; Vilaplana, Jordi; Pelegrí, Carme

2011-01-01

Cerebrovascular dysfunction and β-amyloid peptide deposition on the walls of cerebral blood vessels might be an early event in the development of Alzheimer's disease. Here we studied the time course of amyloid deposition in blood vessels and blood-brain barrier (BBB) disruption in the CA1 subzone of the hippocampus of SAMP8 mice and the association between these two variables. We also studied the association between the amyloid deposition in blood vessels and the recently described amyloid clusters in the parenchyma, as well as the association of these clusters with vessels in which the BBB is disrupted. SAMP8 mice showed greater amyloid deposition in blood vessels than age-matched ICR-CD1 control mice. Moreover, at 12 months of age the number of vessels with a disrupted BBB had increased in both strains, especially SAMP8 animals. At this age, all the vessels with amyloid deposition showed BBB disruption, but several capillaries with an altered BBB showed no amyloid on their walls. Moreover, amyloid clusters showed no spatial association with vessels with amyloid deposition, nor with vessels in which the BBB had been disrupted. Finally, we can conclude that vascular amyloid deposition seems to induce BBB alterations, but BBB disruption may also be due to other factors. Copyright © 2011 S. Karger AG, Basel.

Regulation of Neurovascular Coupling in Autoimmunity to Water and Ion Channels

PubMed Central

Jukkola, Peter; Gu, Chen

2014-01-01

Much progress has been made in understanding autoimmune channelopathies, but the underlying pathogenic mechanisms are not always clear due to broad expression of some channel proteins. Recent studies show that autoimmune conditions that interfere with neurovascular coupling in the central nervous system (CNS) can lead to neurodegeneration. Cerebral blood flow that meets neuronal activity and metabolic demand is tightly regulated by local neural activity. This process of reciprocal regulation involves coordinated actions of a number of cell types, including neurons, glia, and vascular cells. In particular, astrocytic endfeet cover more than 90% of brain capillaries to assist blood-brain barrier (BBB) function, and wrap around synapses and nodes of Ranvier to communicate with neuronal activity. In this review, we highlight four types of channel proteins that are expressed in astrocytes, regarding their structures, biophysical properties, expression and distribution patterns, and related diseases including autoimmune disorders. Water channel aquaporin 4 (AQP4) and inwardly-rectifying potassium (Kir4.1) channels are concentrated in astrocytic endfeet, whereas some voltage-gated Ca2+ and two-pore-domain K+ channels are expressed throughout the cell body of reactive astrocytes. More channel proteins are found in astrocytes under normal and abnormal conditions. This research field will contribute to a better understanding of pathogenic mechanisms underlying autoimmune disorders. PMID:25462580

Flows in films and over flippers

NASA Astrophysics Data System (ADS)

van Nierop, Ernst Adriaan

Three topics in fluid mechanics are dealt with in this dissertation, namely (i) reactive spreading and recoil of oil on water, (ii) free film formation theory and experiment, and (iii) how humpback whale flippers delay stall. Reactive spreading of an oil droplet on water is described in Chapter 1. Small amounts of acid and base were added to the oil and water respectively, such that a surfactant was produced at the interface between the oil and the water, greatly enhancing spreading rates. After the oil drop spreads out to some maximum radius, the drop recoils on a timescale that is indicative of a diffusive process redistributing the surfactant over the entire volume of water. In Chapter 2, the theory of soap film formation by withdrawal from a bath of soapy liquid is reviewed, and the assumptions supporting Frankel's law are challenged. Stress balances that describe film evolution in either extensional or shear flow are rigorously derived and we find that the strength of surface stress terms pick the resulting flow type. With this background in mind, we describe in Chapter 3 how films were made using aqueous solutions of poly(ethylene oxide) or PEO with and without surfactant. The initial thickness of these films agrees well with existing data in the literature for overlapping ranges of the capillary number Ca. For larger Ca numbers, we observe that (i) the addition of SDS results in thinner films, (ii) films can be made that are thicker than the wire thickness, and (iii) films swell in thickness when the withdrawal process stops. Some potential mechanisms are described to explain the novel swelling phenomenon. Finally, in Chapter 4, we model the bumpy flipper of a humpback whale as a perturbed elliptic wing with Joukowski profiles of varying chord length, and combine this with lifting line theory as well as experimental stall characteristics of smooth wings. This model shows that the perturbations rearrange the downwash distribution on the wing, smoothing the transition to stall. Bump amplitude dominates the smoothing, while the wavelength of the bumps plays only a small role.

Transient Droplet Behavior and Droplet Breakup during Bulk and Confined Shear Flow in Blends with One Viscoelastic Component: Experiments, Modelling and Simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cardinaels, Ruth; Verhulst, Kristof; Moldenaers, Paula

2008-07-07

The transient droplet deformation and droplet orientation after inception of shear, the shape relaxation after cessation of shear and droplet breakup during shear, are microscopically studied, both under bulk and confined conditions. The studied blends contain one viscoelastic Boger fluid phase. A counter rotating setup, based on a Paar Physica MCR300, is used for the droplet visualisation. For bulk shear flow, it is shown that the droplet deformation during startup of shear flow and the shape relaxation after cessation of shear flow are hardly influenced by droplet viscoelasticity, even at moderate to high capillary and Deborah numbers. The effects ofmore » droplet viscoelasticity only become visible close to the critical conditions and a novel break-up mechanism is observed. Matrix viscoelasticity has a more pronounced effect, causing overshoots in the deformation and significantly inhibiting relaxation. However, different applied capillary numbers prior to cessation of shear flow, with the Deborah number fixed, still result in a single master curve for shape retraction, as in fully Newtonian systems. The long tail in the droplet relaxation can be qualitatively described with a phenomenological model for droplet deformation, when using a 5-mode Giesekus model for the fluid rheology. It is found that the shear flow history significantly affects the droplet shape evolution and the breakup process in blends with one viscoelastic component. Confining a droplet between two plates accelerates the droplet deformation kinetics, similar to fully Newtonian systems. However, the increased droplet deformation, due to wall effects, causes the steady state to be reached at a later instant in time. Droplet relaxation is less sensitive to confinement, leading to slower relaxation kinetics only for highly confined droplets. For the blend with a viscoelastic droplet, a non-monotonous trend is found for the critical capillary number as a function of the confinement ratio. Finally, experimental data are compared with 3D simulations, performed with a volume-of-fluid algorithm.« less

Real-Time Continuous Glucose Monitoring Reduces the Duration of Hypoglycemia Episodes: A Randomized Trial in Very Low Birth Weight Neonates

PubMed Central

Uettwiller, Florence; Chemin, Aude; Bonnemaison, Elisabeth; Favrais, Géraldine; Saliba, Elie; Labarthe, François

2015-01-01

Objectives Hypoglycemia is frequent in very low birth weight (VLBW) neonates and compromises their neurological outcome. The aim of this study was to compare real-time continuous glucose monitoring system (RT-CGMS) to standard methods by intermittent capillary blood glucose testing in detecting and managing hypoglycemia. Study design Forty-eight VLBW neonates were enrolled in this prospective study. During their 3 first days of life, their glucose level was monitored either by RT-CGMS (CGM-group), or by intermittent capillary glucose testing (IGM-group) associated with a blind-CGMS to detect retrospectively missed hypoglycemia. Outcomes were the number and duration of hypoglycemic (≤50mg/dl) episodes per patient detected by CGMS. Results Forty-three monitorings were analyzed (IGM n = 21, CGM n = 22), with a median recording time of 72 hours. In the IGM group, blind-CGMS revealed a significantly higher number of hypoglycemia episodes than capillary blood glucose testing (1.2±0.4 vs 0.4±0.2 episode/patient, p<0.01). In the CGM-group, the use of RT-CGMS made it possible (i) to detect the same number of hypoglycemia episodes as blind-CGMS (1.2±0.4 episode/patient), (ii) to adapt the glucose supply in neonates with hypoglycemia (increased supply during days 1 and 2), and (iii) to significantly reduce the duration of hypoglycemia episodes per patient (CGM 44[10–140] min versus IGM 95[15–520] min, p<0.05). Furthermore, it reduced the number of blood samples (CGM 16.9±1.0 vs IGM 21.9±1.0 blood sample/patient, p<0.001). Conclusion RT-CGMS played a beneficial role in managing hypoglycemia in VLBW neonates by adjusting the carbohydrate supply to the individual needs and by reducing the duration of hypoglycemia episodes. The clinical significance of the biological differences observed in our study need to be explored. PMID:25590334

Gender differences and lateralization in the distribution pattern of insulin-like growth factor-1 receptor in developing rat hippocampus: an immunohistochemical study.

PubMed

Hami, Javad; Kheradmand, Hamed; Haghir, Hossein

2014-03-01

Numerous investigators have provided data supporting essential roles for insulin-like growth factor-I (IGF-I) in development of the brain. The aim of this study was to immunohistochemically determine the distinct regional distribution pattern of IGF-1 receptor (IGF-IR) expression in various portions of newborn rat hippocampus on postnatal days 0 (P0), 7 (P7), and 14 (P14), with comparison between male/female and right/left hippocampi. We found an overall significant increase in distribution of IGF-IR-positive (IGF-IR+) cells in CA1 from P0 until P14. Although, no marked changes in distribution of IGF-IR+ cells in areas CA2 and CA3 were observed; IGF-IR+ cells in DG decreased until P14. The smallest number of immunoreactive cells was present in CA2 and the highest number in DG at P0. Moreover, in CA1, CA3, and DG, the number of IGF-IR+ cells was markedly higher in both sides of the hippocampus in females. Our data also showed a higher mean number of IGF-IR+ cells in the left hippocampus of female at P7. By contrast, male pups showed a significantly higher number of IGF-IR+ cells in the DG of the right hippocampus. At P14, the mean number of immunoreactive cells in CA1, CA3, and DG areas found to be significantly increased in left side of hippocampus of males, compared to females. These results indicate the existence of a differential distribution pattern of IGF-IR between left-right and male-female hippocampi. Together with other mechanisms, these differences may underlie sexual dimorphism and left-right asymmetry in the hippocampus.

Recombination-pumped XUV lasing in capillary discharges and dynamic z-pinches

NASA Astrophysics Data System (ADS)

Pöckl, M.; Hebenstreit, M.; Fertner, R.; Neger, T.; Aumayr, F.

1996-08-01

A fully time-dependent collisional - radiative model is employed to calculate relevant population densities in a recombining carbon/hydrogen z-pinch plasma. In particular, the dependence of the small signal gain G on the maximum electron temperature and cooling rate, as well as the influence of Lyman-0022-3727/29/8/005/img8 reabsorption, are studied. Although in conditions typical for dynamic z-pinches the maximum electron temperature and cooling rates would, in principle, be sufficiently high, gain on the Balmer-0022-3727/29/8/005/img8 transition is strongly reduced by Lyman-0022-3727/29/8/005/img8 reabsorption. In order to investigate vacuum spark capillary discharges, the system of rate equations is coupled with balance equations of the plasma energy and the total number of heavy particles. The resulting set of equations is solved self-consistently. Results are presented that show the systematic dependence of the small signal gain on electrical input power, wall material, and capillary geometry. High gain coefficients 0022-3727/29/8/005/img11 could be achieved by modelling high-voltage discharges with short ringing periods through capillaries containing boron or carbon. While the maximum achievable gain coefficient for lithium is rather poor 0022-3727/29/8/005/img12 the duration of population inversion would be long enough (a few tens of nanoseconds) to make multi-pass operation possible.

The Study of Compact Plasma Source of SXR of Vacuum Spark Type with Capillary Concentrator and It's Application

NASA Astrophysics Data System (ADS)

Kantsyrev, V. L.; Kopytok, K. I.; Shlyaptseva, A. S.

1994-03-01

The results are presented dealing with the working out and study of the plasma source of soft X-ray (SXR) of the new type. Experimental set up included compact low-inductance vacuum spark (LIVS) with initial energy supply equal up to 2.5 kJ and glass-capillary concentrator (GCC) of SXR. The characteristics of SXR of vacuum spark and properties of SXR were studied using diagnostic complex. The coefficient of conversion of initial energy supply into SXR (η) amounted to 0.01 in range 1.2nm. Value η had peak dependence on atomic number of anode Za. The spectra were recorded belonging to Ne-like, F-like ions of Fe, Cu ions and He-like, H-like ions of Al, Ti, Fe. Glass capillary concentrator consists of about several hundreds glass capillaries Flux density of SXR in focusing spot was up to 105-106 Wt/cm, density of energy is up to 20-30 mJ/cm2 at diameter of SXR focusing spot equal to about 2-3mm in the range 0.7-1.0 nm. The plasma source of the new type is intended for X-ray microscopy, study of influence of SXR on the surface of solid state. It allows to carry out experiments making only on electron synchrotronic sources of SXR.

Analysis and characterization of aluminum chlorohydrate oligocations by capillary electrophoresis.

PubMed

Ouadah, Nesrine; Moire, Claudine; Kuntz, Jean-François; Brothier, Fabien; Cottet, Hervé

2017-04-07

Aluminum chlorohydrates (ACH) are the active ingredients used in most antiperspirant products. ACH is a water soluble aluminum complex which contains several oligomeric polycations of aluminum with degrees of polymerization up to Al 13 or Al 30 . The characterization and quantification of ACH oligo-cations remain a challenging issue of primary interest for developing structure/antiperspirant activity correlations, and for controlling the ACH ingredients. In this work, highly repeatable capillary electrophoresis (CE) separation of A l3 + , Al 13 and Al 30 oligomers contained in ACH samples was obtained at pH 4.8, owing to a careful choice of the background electrolyte counter-ion and chromophore, capillary I.D. and capillary coating. This is the first reported separation of Al 13 and Al 30 oligomers in conditions that are compatible with the aluminum speciation in ACH solution or in conditions of antiperspirant application/formulation. Al 13 and Al 30 effective charge numbers were also determined from the sensitivity of detection in indirect UV detection mode. The relative mass proportion of Al 13 compared to Al 13 +Al 30 could be determined in different aluminum chlorohydrate samples. Due to its simplicity, repeatability/reproducibility, minimal sample preparation and mild analytical conditions, CE appears to be a promising analytical separation technique for the characterization of ACH materials and for the study of structure/antiperspirant activity correlations. Copyright © 2017. Published by Elsevier B.V.

Nano-amylose-2,3-bis(3,5-dimethylphenylcarbamate)-silica hybrid sol immobilized on open tubular capillary column for capillary electrochromatography enantioseparation.

PubMed

Sun, Yaming; Wu, Qi; Shi, Xiaofeng; Gao, Jie; Dong, Shuqing; Zhao, Liang

2018-04-01

The chiral organic-inorganic hybrid materials can exhibit a high loading, and the chiral selector nanoparticles can create efficient stationary phases for open-tubular capillary electrochromatography (OT-CEC). Hence, a novel protocol for the preparation of an OT column coated with nano-amylose-2,3-bis(3,5-dimethylphenylcarbamate) (nano-ABDMPC)-silica hybrid sol through in situ layer-by-layer self-assembly method was developed for CEC enantioseparation. By controlling the assembly cycle number of nano-ABDMPC-silica hybrid sol, a homogeneous, dense and stable coating was successfully prepared, which was confirmed by SEM and elemental analysis. As the main parameter influencing the chiral separating effect, the nano-ABDMPC bearing 3-(triethoxysilyl)propyl residues concentration was investigated. The experimental results showed that 10.0 mg/mL nano-ABDMPC bearing 3-(triethoxysilyl)propyl residues coated OT capillary column possessed chiral recognition ability toward the six enantiomers (phenylalanine, tyrosine, tryptophan, phenethyl alcohol, 1-phenyl-2-propanol, and Tröger's base) at some of the different conditions tested. Additionally, the coated OT column revealed adequate repeatability concerning run-to-run, day-to-day and column-to-column. These results demonstrated the promising applicability of nano-ABDMPC-silica hybrid sol coated OT column in CEC enantioseparations. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Definitive screening design enables optimization of LC-ESI-MS/MS parameters in proteomics.

PubMed

Aburaya, Shunsuke; Aoki, Wataru; Minakuchi, Hiroyoshi; Ueda, Mitsuyoshi

2017-12-01

In proteomics, more than 100,000 peptides are generated from the digestion of human cell lysates. Proteome samples have a broad dynamic range in protein abundance; therefore, it is critical to optimize various parameters of LC-ESI-MS/MS to comprehensively identify these peptides. However, there are many parameters for LC-ESI-MS/MS analysis. In this study, we applied definitive screening design to simultaneously optimize 14 parameters in the operation of monolithic capillary LC-ESI-MS/MS to increase the number of identified proteins and/or the average peak area of MS1. The simultaneous optimization enabled the determination of two-factor interactions between LC and MS. Finally, we found two parameter sets of monolithic capillary LC-ESI-MS/MS that increased the number of identified proteins by 8.1% or the average peak area of MS1 by 67%. The definitive screening design would be highly useful for high-throughput analysis of the best parameter set in LC-ESI-MS/MS systems.

Study on clinical effect and immunologic mechanism of infants capillary bronchitis secondary bronchial asthma treated with bacterial lysates Broncho-Vaxom.

PubMed

Han, R-F; Li, H-Y; Wang, J-W; Cong, X-J

2016-05-01

To study the clinical effects and immunologic mechanism of infant capillary bronchitis secondary bronchial asthma treated with bacterial lysates (Broncho-Vaxom OM-85BV). Between February 2013 and February 2014, 136 infant capillary bronchitis secondary bronchial asthma cases were chosen. This research was approved by Ethics Committee in our hospital and obtained the informed consent right from patients and guardians. Patients were divided into the control group (n = 62) and the observation group (n = 74) using random number table method. Patients in the control group were treated with normal glucocorticoid atomizing inhalation, aminophylline and antibiotic treatment. In the observation group besides the abovementioned treatment, we added Broncho-Vaxom OM-85BV, qd po for 10 days continuously and quitted it for 20 days. This continued for a total of 3 months. Follow-ups were set for about one year to compare the effects. The onset frequency and duration of capillary bronchitis and asthma in observation group declined remarkably compared with control group and the differences were statistically significant (p < 0.05). The level of IL-17 and IL-4 in the observation group decreased significantly, whereas, the level of IL-10 and IFN- γ increased considerably. Differences were all statistically significant (p < 0.05). Peripheral blood CD4+ T lymphocytes in the observation group patients expressed lower levels of nicotinic acetylcholine receptors α7 (α7nAChR) compared to the control group. Then difference was statistically significant (p < 0.05). Broncho-Vaxom OM-85BV reduced the onset of infant capillary bronchitis secondary bronchial asthma, relating to the reduced inflammation reaction. It also regulated the immunologic function of Th1/Th2, and lowered the α7nAChR level.

Tuning preparation conditions towards optimized separation performance of thermally polymerized organo-silica monolithic columns in capillary liquid chromatography.

PubMed

Gharbharan, Deepa; Britsch, Denae; Soto, Gabriela; Weed, Anna-Marie Karen; Svec, Frantisek; Zajickova, Zuzana

2015-08-21

Tuning of preparation conditions, such as variations in the amount of a porogen, concentration of an aqueous acid catalyst, and adjustment in polymerization temperature and time, towards optimized chromatographic performance of thermally polymerized monolithic capillaries prepared from 3-(methacryloyloxy)propyltrimethoxysilane has been carried out. Performance of capillary columns in reversed-phase liquid chromatography was assessed utilizing various sets of solutes. Results describing hydrophobicity, steric selectivity, and extent of hydrogen bonding enabled comparison of performance of hybrid monolithic columns prepared under thermal (TSG) and photopolymerized (PSG) conditions. Reduced amounts of porogen in the polymerization mixture, and prolonged reaction times were necessary for the preparation of monolithic columns with enhanced retention and column efficiency that reached to 111,000 plates/m for alkylbenzenes with shorter alkyl chains. Both increased concentration of catalyst and higher temperature resulted in faster polymerization but inevitably in insufficient time for pore formation. Thermally polymerized monoliths produced surfaces, which were slightly more hydrophobic (a methylene selectivity of 1.28±0.002 TSG vs 1.20±0.002 PSG), with reduced number of residual silanols (a caffeine/phenol selectivity of 0.13±0.001 TSG vs 0.17±0.003 PSG). However, steric selectivity of 1.70±0.01 was the same for both types of columns. The batch-to-batch repeatability was better using thermal initiation compared to monolithic columns prepared under photopolymerized conditions. RSD for retention factor of benzene was 3.7% for TSG capillaries (n=42) vs. 6.6% for PSG capillaries (n=18). A similar trend was observed for columns prepared within the same batch. Copyright © 2015 Elsevier B.V. All rights reserved.

Laser illumination of multiple capillaries that form a waveguide

DOEpatents

Dhadwal, Harbans S.; Quesada, Mark A.; Studier, F. William

1998-08-04

A system and method are disclosed for efficient laser illumination of the interiors of multiple capillaries simultaneously, and collection of light emitted from them. Capillaries in a parallel array can form an optical waveguide wherein refraction at the cylindrical surfaces confines side-on illuminating light to the core of each successive capillary in the array. Methods are provided for determining conditions where capillaries will form a waveguide and for assessing and minimizing losses due to reflection. Light can be delivered to the arrayed capillaries through an integrated fiber optic transmitter or through a pair of such transmitters aligned coaxially at opposite sides of the array. Light emitted from materials within the capillaries can be carried to a detection system through optical fibers, each of which collects light from a single capillary, with little cross talk between the capillaries. The collection ends of the optical fibers can be in a parallel array with the same spacing as the capillary array, so that the collection fibers can all be aligned to the capillaries simultaneously. Applicability includes improving the efficiency of many analytical methods that use capillaries, including particularly high-throughput DNA sequencing and diagnostic methods based on capillary electrophoresis.

Laser illumination of multiple capillaries that form a waveguide

DOEpatents

Dhadwal, H.S.; Quesada, M.A.; Studier, F.W.

1998-08-04

A system and method are disclosed for efficient laser illumination of the interiors of multiple capillaries simultaneously, and collection of light emitted from them. Capillaries in a parallel array can form an optical waveguide wherein refraction at the cylindrical surfaces confines side-on illuminating light to the core of each successive capillary in the array. Methods are provided for determining conditions where capillaries will form a waveguide and for assessing and minimizing losses due to reflection. Light can be delivered to the arrayed capillaries through an integrated fiber optic transmitter or through a pair of such transmitters aligned coaxially at opposite sides of the array. Light emitted from materials within the capillaries can be carried to a detection system through optical fibers, each of which collects light from a single capillary, with little cross talk between the capillaries. The collection ends of the optical fibers can be in a parallel array with the same spacing as the capillary array, so that the collection fibers can all be aligned to the capillaries simultaneously. Applicability includes improving the efficiency of many analytical methods that use capillaries, including particularly high-throughput DNA sequencing and diagnostic methods based on capillary electrophoresis. 35 figs.

Device to improve detection in electro-chromatography

DOEpatents

Garguilo, Michael G.; Paul, Phillip H.; Rakestraw, David J.

2000-01-01

Apparatus and method for improving the resolution of non-pressure driven capillary chromatographic systems, and particularly for capillary electrochromatography (CEC) systems. By reducing the cross-sectional area of a packed capillary column by means of a second open capillary contiguous with the outlet end of a packed capillary column, where the packed capillary column has a cross sectional area of between about 2 and 5 times that of the open capillary column, the phenomenon of band broadening in the transition region between the open capillary and the packed capillary column, where the individual components of the mixture are analyzed, can be eliminated, thereby providing for a significant improvement in resolution and more accurate detection and analysis.

Device to improve detection in electro-chromatography

DOEpatents

Garguilo, Michael G.; Paul, Phillip H.; Rakestraw, David J.

2002-01-01

Apparatus and method for improving the resolution of non-pressure driven capillary chromatographic systems, and particularly for capillary electrochromatography (CEC) systems. By reducing the cross-sectional area of a packed capillary column by means of a second open capillary contiguous with the outlet end of a packed capillary column, where the packed capillary column has a cross sectional area of between about 2 and 5 times that of the open capillary column, the phenomenon of band broadening in the transition region between the open capillary and the packed capillary column, where the individual components of the mixture are analyzed, can be eliminated, thereby providing for a significant improvement in resolution and more accurate detection and analysis.

Sheathless interface for coupling capillary electrophoresis with mass spectrometry

DOEpatents

Wang, Chenchen; Tang, Keqi; Smith, Richard D.

2014-06-17

A sheathless interface for coupling capillary electrophoresis (CE) with mass spectrometry is disclosed. The sheathless interface includes a separation capillary for performing CE separation and an emitter capillary for electrospray ionization. A portion of the emitter capillary is porous or, alternatively, is coated to form an electrically conductive surface. A section of the emitter capillary is disposed within the separation capillary, forming a joint. A metal tube, containing a conductive liquid, encloses the joint.

Design of Capillary Flows with Spatially Graded Porous Films

NASA Astrophysics Data System (ADS)

Joung, Young Soo; Figliuzzi, Bruno Michel; Buie, Cullen

2013-11-01

We have developed a new capillary tube model, consisting of multi-layered capillary tubes oriented in the direction of flow, to predict capillary speeds on spatially graded porous films. Capillary flows through thin porous media have been widely utilized for small size liquid transport systems. However, for most media it is challenging to realize arbitrary shapes and spatially functionalized micro-structures with variable flow properties. Therefore, conventional media can only be used for capillary flows obeying Washburn's equation and the modifications thereof. Given this background, we recently developed a method called breakdown anodization (BDA) to produce highly wetting porous films. The resulting surfaces show nearly zero contact angles and fast water spreading speed. Furthermore, capillary pressure and spreading diffusivity can be expressed as functions of capillary height when customized electric fields are used in BDA. From the capillary tube model, we derived a general capillary flow equation of motion in terms of capillary pressure and spreading diffusivity. The theoretical model shows good agreement with experimental capillary flows. The study will provide novel design methodologies for paper-based microfluidic devices.

Separation of attogram terpenes by the capillary zone electrophoresis with fluorometric detection.

PubMed

Kubesová, Anna; Horká, Marie; Růžička, Filip; Slais, Karel; Glatz, Zdeněk

2010-11-12

An original method based on capillary zone electrophoresis with fluorimetric detection has been developed for the determination of terpenic compounds. The method is based on the separation of a terpenes dynamically labeled by the non-ionogenic tenside poly(ethylene glycol) pyrenebutanoate, which was used previously for the labeling of biopolymers. The background electrolytes were composed of taurine-Tris buffer (pH 8.4). In addition to the non-ionogenic tenside aceton and poly(ethylene glycol) were used as the additives. The capillary zone electrophoresis with fluorometric detection at the excitation wavelength 335 nm and the emission wavelength 463 nm was successfully applied to the analysis of tonalid, cholesterol, vitamin A, ergosterol, estrone and farnesol at level of 10(-17) mol L(-1). Farnesol, is produced by Candida albicans as an extracellular quorum-sensing molecule that influences expression of a number of virulence factors, especially morphogenesis and biofilm formation. It enables this yeast to cause serious nosocomial infections. The sensitivity of this method was demonstrated on the separation of farnesol directly from the cultivation medium. Copyright © 2010 Elsevier B.V. All rights reserved.

Can flexibility help you float?

NASA Astrophysics Data System (ADS)

Burton, L. J.; Bush, J. W. M.

2012-10-01

We consider the role of flexibility in the weight-bearing characteristics of bodies floating at an interface. Specifically, we develop a theoretical model for a two-dimensional thin floating plate that yields the maximum stable plate load and optimal stiffness for weight support. Plates small relative to the capillary length are primarily supported by surface tension, and their weight-bearing potential does not benefit from flexibility. Above a critical size comparable to the capillary length, flexibility assists interfacial flotation. For plates on the order of and larger than the capillary length, deflection from an initially flat shape increases the force resulting from hydrostatic pressure, allowing the plate to support a greater load. In this large plate limit, the shape that bears the most weight is a semicircle, which displaces the most fluid above the plate for a fixed plate length. Exact results for maximum weight-bearing plate shapes are compared to analytic approximations made in the limits of large and small plate sizes. The value of flexibility for floating to a number of biological organisms is discussed in light of our study.

Capillary Ion Concentration Polarization for Power-Free Salt Purification

NASA Astrophysics Data System (ADS)

Park, Sungmin; Jung, Yeonsu; Cho, Inhee; Kim, Ho-Young; Kim, Sung Jae

2014-11-01

In this presentation, we experimentally and theoretically demonstrated the capillary based ion concentration polarization for power-free salt purification system. Traditional ion concentration polarization phenomenon has been studied for a decade for both fundamental nanoscale fluid dynamics and novel engineering applications such as desalination, preconcentration and energy harvesting devices. While the conventional system utilizes an external power source, the system based on capillary ion concentration polarization is capable of perm-selective ion transportation only by capillarity so that the same ion depletion zone can be formed without any external power sources. An ion concentration profile near the nanostructure was tracked using fluorescent probes and analyzed by solving the modified Nernst-Planck equation. As a result, the concentration in the vicinity of the nanostructure was at least 10 times lower than that of bulk electrolyte and thus, the liquid absorbed into the nanostructure had the low concentration. This mechanism can be used for the power free salt purification system which would be significantly useful in underdeveloped and remote area. This work was supported by Samsung Research Funding Center of Samsung Electronics under Project Number SRFC-MA1301-02.

Determining a membrane's shear modulus, independent of its area-dilatation modulus, via capsule flow in a converging micro-capillary.

PubMed

Dimitrakopoulos, P; Kuriakose, S

2015-04-14

Determination of the elastic properties of the membrane of artificial capsules is essential for the better design of the various devices that are utilized in their engineering and biomedical applications. However this task is complicated owing to the combined effects of the shear and area-dilatation moduli on the capsule deformation. Based on computational investigation, we propose a new methodology to determine a membrane's shear modulus, independent of its area-dilatation modulus, by flowing strain-hardening capsules in a converging micro-capillary of comparable size under Stokes flow conditions, and comparing the experimental measurements of the capsule elongation overshooting with computational data. The capsule prestress, if any, can also be determined with the same methodology. The elongation overshooting is practically independent of the viscosity ratio for low and moderate viscosity ratios, and thus a wide range of capsule fluids can be employed. Our proposed experimental device can be readily produced via glass fabrication while owing to the continuous flow in the micro-capillary, the characterization of a large number of artificial capsules is possible.

The potential of SNP-based PCR-RFLP capillary electrophoresis analysis to authenticate and detect admixtures of Mediterranean olive oils.

PubMed

Bazakos, Christos; Khanfir, Emna; Aoun, Mariem; Spano, Thodhoraq; Zein, Zeina El; Chalak, Lamis; Riachy, Milad El; Abou-Sleymane, Gretta; Ali, Sihem Ben; Grati Kammoun, Naziha; Kalaitzis, Panagiotis

2016-07-01

Authentication and traceability of extra virgin olive oil is a challenging research task due to the complexity of fraudulent practices. In this context, the monovarietal olive oils of Protected Designation of Origin (PDO) and Protected Geographical Indication (PGI) require new tests and cutting edge analytical technologies to detect mislabeling and misleading origin. Toward this direction, DNA-based technologies could serve as a complementary to the analytical techniques assay. Single nucleotide polymorphisms are ideal molecular markers since they require short PCR analytical targets which are a prerequisite for forensic applications in olive oil sector. In the present study, a small number of polymorphic SNPs were used with an SNP-based PCR-RFLP capillary electrophoresis platform to discriminate six out of 13 monovarietal olive oils of Mediterranean origin from three different countries, Greece, Tunisia, and Lebanon. Moreover, the high sensitivity of capillary electrophoresis in combination with the DNA extraction protocol lowered the limit of detection to 10% in an admixture of Tsounati in a Koroneiki olive oil matrix. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermocapillary phenomena and performance limitations of a wickless heat pipe in microgravity.

PubMed

Kundan, Akshay; Plawsky, Joel L; Wayner, Peter C; Chao, David F; Sicker, Ronald J; Motil, Brian J; Lorik, Tibor; Chestney, Louis; Eustace, John; Zoldak, John

2015-04-10

A counterintuitive, thermocapillary-induced limit to heat- pipe performance was observed that is not predicted by current thermal-fluid models. Heat pipes operate under a number of physical constraints including the capillary, boiling, sonic, and entrainment limits that fundamentally affect their performance. Temperature gradients near the heated end may be high enough to generate significant Marangoni forces that oppose the return flow of liquid from the cold end. These forces are believed to exacerbate dry out conditions and force the capillary limit to be reached prematurely. Using a combination of image and thermal data from experiments conducted on the International Space Station with a transparent heat pipe, we show that in the presence of significant Marangoni forces, dry out is not the initial mechanism limiting performance, but that the physical cause is exactly the opposite behavior: flooding of the hot end with liquid. The observed effect is a consequence of the competition between capillary and Marangoni-induced forces. The temperature signature of flooding is virtually identical to dry out, making diagnosis difficult without direct visual observation of the vapor-liquid interface.

Soil-Moisture Retention Curves, Capillary Pressure Curves, and Mercury Porosimetry: A Theoretical and Computational Investigation of the Determination of the Geometric Properties of the Pore Space

NASA Astrophysics Data System (ADS)

Strand, T. E.; Wang, H. F.

2003-12-01

Immiscible displacement protocols have long been used to infer the geometric properties of the void space in granular porous media. The three most commonly used experimental techniques are the measurement of soil-moisture retention curves and relative permeability-capillary pressure-saturation relations, as well as mercury intrusion porosimetry experiments. A coupled theoretical and computational investigation was performed that provides insight into the limitations associated with each technique and quantifies the relationship between experimental observations and the geometric properties of the void space. It is demonstrated that the inference of the pore space geometry from both mercury porosimetry experiments and measurements of capillary pressure curves is influenced by trapping/mobilization phenomena and subject to scaling behavior. In addition, both techniques also assume that the capillary pressure at a location on the meniscus can be approximated by a pressure difference across a region or sample. For example, when performing capillary pressure measurements, the capillary pressure, taken to be the difference between the injected fluid pressure at the inlet and the defending fluid pressure at the outlet, is increased in a series of small steps and the fluid saturation is measured each time the system reaches steady. Regions of defending fluid that become entrapped by the invading fluid can be subsequently mobilized at higher flow rates (capillary pressures), contributing to a scale-dependence of the capillary pressure-saturation curve that complicates the determination of the properties of the pore space. This scale-dependence is particularly problematic for measurements performed at the core scale. Mercury porosimetry experiments are subject to similar limitations. Trapped regions of defending fluid are also present during the measurement of soil-moisture retention curves, but the effects of scaling behavior on the evaluation of the pore space properties from the immiscible displacement structure are much simpler to account for due to the control of mobilization phenomena. Some mobilization may occur due to film flow, but this can be limited by keeping time scales relatively small or exploited at longer time scales in order to quantify the rate of film flow. Computer simulations of gradient-stabilized drainage and imbibition to the (respective) equilibrium positions were performed using a pore-scale modified invasion percolation (MIP) model in order to quantify the relationship between the saturation profile and the geometric properties of the void space. These simulations are similar to the experimental measurement of soil-moisture retention curves. Results show that the equilibrium height and the width of the equilibrium fringe depend on two length scale distributions, one controlling the imbibition equilibrium structure and the other controlling the drainage structure. The equilibrium height is related to the mean value of the appropriate distribution as described by Jurin's law, and the width of the equilibrium fringe scales as a function of a combined parameter, the Bond number, Bo, divided by the coefficient of variation (cov). Simulations also demonstrate that the apparent radius distribution obtained from saturation profiles using direct inversion by Jurin's law is a subset of the actual distribution in the porous medium. The relationship between the apparent and actual radius distributions is quantified in terms of the combined parameter, Bo/cov, and the mean coordination number of the porous medium.

Morphometric assessment of the dermal microcirculation in patients with chronic venous insufficiency.

PubMed

Pappas, P J; DeFouw, D O; Venezio, L M; Gorti, R; Padberg, F T; Silva, M B; Goldberg, M C; Durán, W N; Hobson, R W

1997-11-01

Ultrastructural assessments of the dermal microcirculation in patients with chronic venous insufficiency have been limited to qualitative morphologic descriptions of venous ulcer edges or venous stasis dermatitis. The purpose of this investigation was to quantify differences in endothelial cell structure and local cell type with emphasis on leukocytes and their relationship to arterioles, capillaries, and postcapillary venules (PCVs). Two 4.0 mm punch biopsies were obtained from areas of dermal stasis skin changes in the gaiter region of the leg, as well as from noninvolved areas of skin in the ipsilateral thigh, from 35 patients: CEAP class 4 (11 patients), class 5 (9 patients), class 6 (10 patients), and five normal skin biopsies from patients without chronic venous insufficiency. Electron microscopy was performed on sections at 6700x and 23,800x magnification. At 6700x endothelial cell thickness was determined, and the number of fibroblasts, leukocytes, and mast cells were recorded relative to their proximity to arterioles, capillaries, and PCVs. Similarly, at 23,800x endothelial cell vesicle density, interendothelial junctional widths, and basal lamina thickness (cuff width) were measured. Preliminary evaluation for the presence of transforming growth factor-beta 1 (TGF-beta 1) was performed on three patients using reverse transcriptase-polymerase chain reaction (RT-PCR). Quantitative measurements demonstrated increased mast cell content for class 4 and 5 patients around arterioles and PCVs and increased macrophage numbers for class 6 patients around PCVs (p < 0.05). Fibroblasts were the most common cells observed; however, no differences were demonstrated between groups. No differences were observed in interendothelial junctional widths or vesicle densities in arterioles, capillaries, or PCVs. Basal lamina thickness was increased only at the capillary level (p < 0.05). The results of RT-PCR for TGF-beta 1 messenger RNA were positive in the three patients studied. Our data suggest that (1) mast cells play a role in the pathogenesis of chronic venous insufficiency; (2) the effects of mast cells, macrophages, or both may be mediated in part by TGF-beta 1; and (3) capillary cuff formation is not associated with widened interendothelial gap junctions, but may be a result of enhanced vesicular transport rate or conformational changes in the interendothelial glycocalyx.

Equation of state of wet granular matter.

PubMed

Fingerle, A; Herminghaus, S

2008-01-01

An expression for the near-contact pair correlation function of D -dimensional weakly polydisperse hard spheres is presented, which arises from elementary free-volume arguments. Its derivative at contact agrees very well with our simulations for D=2 . For jammed states, the expression predicts that the number of exact contacts is equal to 2D, in agreement with established simulations. When the particles are wetted, they interact by the formation and rupture of liquid capillary bridges. Since formation and rupture events of capillary bonds are well separated in configuration space, the interaction is hysteretic with a characteristic energy loss Ecb. The pair correlation is strongly affected by this capillary interaction depending on the liquid-bond status of neighboring particles. A theory is derived for the nonequilibrium probability currents of the capillary interaction which determines the pair correlation function near contact. This finally yields an analytic expression for the equation of state, P=P(N/V,T), of wet granular matter for D=2, valid in the complete density range from gas to jamming. Driven wet granular matter exhibits a van der Waals-like unstable branch at granular temperatures TT, is of relevance for aggregation in general, simulations have been performed which show very good agreement with the theoretically predicted coordination K of capillary bonds as a function of the bond length scrit. This result implies that particles that stick at the surface, scrit=0, form isostatic clusters. An extension of the theory in which the bridge coordination number K plays the role of a self-consistent mean-field is proposed.

Equation of state of wet granular matter

NASA Astrophysics Data System (ADS)

Fingerle, A.; Herminghaus, S.

2008-01-01

An expression for the near-contact pair correlation function of D -dimensional weakly polydisperse hard spheres is presented, which arises from elementary free-volume arguments. Its derivative at contact agrees very well with our simulations for D=2 . For jammed states, the expression predicts that the number of exact contacts is equal to 2D, in agreement with established simulations. When the particles are wetted, they interact by the formation and rupture of liquid capillary bridges. Since formation and rupture events of capillary bonds are well separated in configuration space, the interaction is hysteretic with a characteristic energy loss Ecb . The pair correlation is strongly affected by this capillary interaction depending on the liquid-bond status of neighboring particles. A theory is derived for the nonequilibrium probability currents of the capillary interaction which determines the pair correlation function near contact. This finally yields an analytic expression for the equation of state, P=P(N/V,T) , of wet granular matter for D=2 , valid in the complete density range from gas to jamming. Driven wet granular matter exhibits a van der Waals-like unstable branch at granular temperatures T

De novo germline and postzygotic mutations in AKT3, PIK3R2 and PIK3CA cause a spectrum of related megalencephaly syndromes

PubMed Central

Rivière, Jean-Baptiste; Mirzaa, Ghayda M.; O’Roak, Brian J.; Beddaoui, Margaret; Alcantara, Diana; Conway, Robert L.; St-Onge, Judith; Schwartzentruber, Jeremy A.; Gripp, Karen W.; Nikkel, Sarah M.; Worthylake, Thea; Sullivan, Christopher T.; Ward, Thomas R.; Butler, Hailly E.; Kramer, Nancy A.; Albrecht, Beate; Armour, Christine M.; Armstrong, Linlea; Caluseriu, Oana; Cytrynbaum, Cheryl; Drolet, Beth A.; Innes, A. Micheil; Lauzon, Julie L.; Lin, Angela E.; Mancini, Grazia M. S.; Meschino, Wendy S.; Reggin, James D.; Saggar, Anand K.; Lerman-Sagie, Tally; Uyanik, Gökhan; Weksberg, Rosanna; Zirn, Birgit; Beaulieu, Chandree L.; Majewski, Jacek; Bulman, Dennis E.; O’Driscoll, Mark; Shendure, Jay; Graham, John M.; Boycott, Kym M.; Dobyns, William B.

2012-01-01

Megalencephaly-capillary malformation (MCAP) and megalencephaly-polymicrogyria-polydactyly-hydrocephalus (MPPH) syndromes are sporadic overgrowth disorders associated with markedly enlarged brain size and other recognizable features1-5. We performed exome sequencing in three families with MCAP or MPPH and confirmed our initial observations in exomes from 7 MCAP and 174 control individuals, as well as in 40 additional megalencephaly subjects using a combination of Sanger sequencing, restriction-enzyme assays, and targeted deep sequencing. We identified de novo germline or postzygotic mutations in three core components of the phosphatidylinositol-3-kinase (PI3K)/AKT pathway. These include two mutations of AKT3, one recurrent mutation of PIK3R2 in 11 unrelated MPPH families, and 15 mostly postzygotic mutations of PIK3CA in 23 MCAP and one MPPH patients. Our data highlight the central role of PI3K/AKT signaling in vascular, limb and brain development, and emphasize the power of massively parallel sequencing in a challenging context of phenotypic and genetic heterogeneity combined with postzygotic mosaicism. PMID:22729224

De novo germline and postzygotic mutations in AKT3, PIK3R2 and PIK3CA cause a spectrum of related megalencephaly syndromes.

PubMed

Rivière, Jean-Baptiste; Mirzaa, Ghayda M; O'Roak, Brian J; Beddaoui, Margaret; Alcantara, Diana; Conway, Robert L; St-Onge, Judith; Schwartzentruber, Jeremy A; Gripp, Karen W; Nikkel, Sarah M; Worthylake, Thea; Sullivan, Christopher T; Ward, Thomas R; Butler, Hailly E; Kramer, Nancy A; Albrecht, Beate; Armour, Christine M; Armstrong, Linlea; Caluseriu, Oana; Cytrynbaum, Cheryl; Drolet, Beth A; Innes, A Micheil; Lauzon, Julie L; Lin, Angela E; Mancini, Grazia M S; Meschino, Wendy S; Reggin, James D; Saggar, Anand K; Lerman-Sagie, Tally; Uyanik, Gökhan; Weksberg, Rosanna; Zirn, Birgit; Beaulieu, Chandree L; Majewski, Jacek; Bulman, Dennis E; O'Driscoll, Mark; Shendure, Jay; Graham, John M; Boycott, Kym M; Dobyns, William B

2012-06-24

Megalencephaly-capillary malformation (MCAP) and megalencephaly-polymicrogyria-polydactyly-hydrocephalus (MPPH) syndromes are sporadic overgrowth disorders associated with markedly enlarged brain size and other recognizable features. We performed exome sequencing in 3 families with MCAP or MPPH, and our initial observations were confirmed in exomes from 7 individuals with MCAP and 174 control individuals, as well as in 40 additional subjects with megalencephaly, using a combination of Sanger sequencing, restriction enzyme assays and targeted deep sequencing. We identified de novo germline or postzygotic mutations in three core components of the phosphatidylinositol 3-kinase (PI3K)-AKT pathway. These include 2 mutations in AKT3, 1 recurrent mutation in PIK3R2 in 11 unrelated families with MPPH and 15 mostly postzygotic mutations in PIK3CA in 23 individuals with MCAP and 1 with MPPH. Our data highlight the central role of PI3K-AKT signaling in vascular, limb and brain development and emphasize the power of massively parallel sequencing in a challenging context of phenotypic and genetic heterogeneity combined with postzygotic mosaicism.

Surface roughness effects on contact line motion with small capillary number

NASA Astrophysics Data System (ADS)

Yang, Feng-Chao; Chen, Xiao-Peng; Yue, Pengtao

2018-01-01

In this work, we investigate how surface roughness influences contact line dynamics by simulating forced wetting in a capillary tube. The tube wall is decorated with microgrooves and is intrinsically hydrophilic. A phase-field method is used to capture the fluid interface and the moving contact line. According to the numerical results, a criterion is proposed to judge whether the grooves are entirely wetted or not at vanishing capillary numbers. When the contact line moves over a train of grooves, the apparent contact angle exhibits a periodic nature, no matter whether the Cassie-Baxter or the Wenzel state is achieved. The oscillation amplitude of apparent contact angle is analyzed and found to be inversely proportional to the interface area. The contact line motion can be characterized as stick-jump-slip in the Cassie-Baxter state and stick-slip in the Wenzel state. By comparing to the contact line dynamics on smooth surfaces, equivalent microscopic contact angles and slip lengths are obtained. The equivalent slip length in the Cassie-Baxter state agrees well with the theoretical model in the literature. The equivalent contact angles are, however, much greater than the predictions of the Cassie-Baxter model and the Wenzel model for equilibrium stable states. Our results reveal that the pinning of the contact line at surface defects effectively enhances the hydrophobicity of rough surfaces, even when the surface material is intrinsically hydrophilic and the flow is under the Wenzel state.

Effects of plastic mulches and high tunnel raspberry production systems on soil physicochemical quality indicators

NASA Astrophysics Data System (ADS)

Domagała-Świątkiewicz, Iwona; Siwek, Piotr

2018-01-01

In horticulture, degradable materials are desirable alternatives to plastic films. Our aim was to study the impact of soil plastic mulching on the soil properties in the high tunnel and open field production systems of raspberry. The raised beds were mulched with a polypropylene non-woven and two degradable mulches: polypropylene with a photodegradant and non-woven polylactide. The results indicated that the system of raspberry production, as well as the type of mulching had significant impact on soil organic carbon stock, moisture content and water stable aggregate amount. Soils taken from the open field system had a lower bulk density and water stability aggregation index, but higher organic carbon and capillary water content as compared to soils collected from high tunnel conditions. In comparison with the open field system, soil salinity was also found to be higher in high tunnel, as well as with higher P, Mg, Ca, S, Na and B content. Furthermore, mulch covered soils had more organic carbon amount than the bare soils. Soil mulching also enhanced the water capacity expressed as a volume of capillary water content. In addition, mulching improved the soil structure in relation to the bare soil, in particular, in open field conditions. The impact of the compared mulches on soil quality indicators was similar.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheshire, Michael C.; Stack, Andrew G.; Carey, J. William

Mineral reactions during CO 2 sequestration will change the pore-size distribution and pore surface characteristics, complicating permeability and storage security predictions. In this study, we report a small/wide angle scattering study of wellbore cement that has been exposed to carbon dioxide for three decades. We have constructed detailed contour maps that describe local porosity distributions and the mineralogy of the sample and relate these quantities to the carbon dioxide reaction front on the cement. We find that the initial bimodal distribution of pores in the cement, 1–2 and 10–20 nm, is affected differently during the course of carbonation reactions. Initialmore » dissolution of cement phases occurs in the 10–20 nm pores and leads to the development of new pore spaces that are eventually sealed by CaCO 3 precipitation, leading to a loss of gel and capillary nanopores, smoother pore surfaces, and reduced porosity. This suggests that during extensive carbonation of wellbore cement, the cement becomes less permeable because of carbonate mineral precipitation within the pore space. Additionally, the loss of gel and capillary nanoporosities will reduce the reactivity of cement with CO 2 due to reactive surface area loss. Finally, this work demonstrates the importance of understanding not only changes in total porosity but also how the distribution of porosity evolves with reaction that affects permeability.« less

In-house-made capillary electrophoresis instruments coupled with contactless conductivity detection as a simple and inexpensive solution for water analysis: a case study in Vietnam.

PubMed

Duong, Hong Anh; Le, Minh Duc; Nguyen, Kim Diem Mai; Hauser, Peter C; Pham, Hung Viet; Mai, Thanh Duc

2015-11-01

A simple and inexpensive method for the determination of various ionic species in different water matrices is discussed in this study. The approach is based on the employment of in-house-made capillary electrophoresis (CE) instruments with capacitively coupled contactless conductivity detection (C(4)D), which can be realized even when only a modest financial budget and limited expertise are available. Advantageous features and considerations of these instruments are detailed following their pilot deployment in Vietnam. Different categories of ionic species, namely major inorganic cations (K(+), Na(+), Ca(2+), Mg(2+), and NH4(+)) and major inorganic anions (Cl(-), NO3(-), NO2(-), SO4(2-), and phosphate), in different water matrices in Vietnam were determined using these in-house fabricated instruments. Inorganic trivalent arsenic (As(iii)), which is the most abundant form of arsenic in reducing groundwater, was determined by CE-C(4)D. The effect of some interfering ions in groundwater on the analytical performance was investigated and is highlighted. The results from in-house-made CE-C(4)D-instruments were cross-checked with those obtained using the standard methods (AAS, AES, UV and IC), with correlation coefficients r(2) ≥ 0.9 and deviations from the referenced results less than 15%.

Ultrasound-Mediated Microbubble Destruction (UMMD) Facilitates the Delivery of CA19-9 Targeted and Paclitaxel Loaded mPEG-PLGA-PLL Nanoparticles in Pancreatic Cancer.

PubMed

Xing, Lingxi; Shi, Qiusheng; Zheng, Kailiang; Shen, Ming; Ma, Jing; Li, Fan; Liu, Yang; Lin, Lizhou; Tu, Wenzhi; Duan, Yourong; Du, Lianfang

2016-01-01

Pancreatic cancer, one of the most lethal human malignancies with dismal prognosis, is refractory to existing radio-chemotherapeutic treatment modalities. There is a critical unmet need to develop effective approaches, especially for targeted pancreatic cancer drug delivery. Targeted and drug-loaded nanoparticles (NPs) combined with ultrasound-mediated microbubble destruction (UMMD) have been shown to significantly increase the cellular uptake in vitro and drug retention in vivo, suggesting a promising strategy for cancer therapy. In this study, we synthesized pancreatic cancer-targeting organic NPs that were modified with anti CA19-9 antibody and encapsulated paclitaxol (PTX). The three-block copolymer methoxy polyethylene glycol-polylacticco-glycolic acid-polylysine (mPEG-PLGA-PLL) constituted the skeleton of the NPs. We speculated that the PTX-NPs-anti CA19-9 would circulate long-term in vivo, "actively target" pancreatic cancer cells, and sustainably release the loaded PTX while UMMD would "passively target" the irradiated tumor and effectively increase the permeability of cell membrane and capillary gaps. Our results demonstrated that the combination of PTX-NPs-anti CA19-9 with UMMD achieved a low IC50, significant cell cycle arrest, and cell apoptosis in vitro. In mouse pancreatic tumor xenografts, the combined application of PTX-NP-anti CA19-9 NPs with UMMD attained the highest tumor inhibition rate, promoted the pharmacokinetic profile by increasing AUC, t1/2, and mean residence time (MRT), and decreased clearance. Consequently, the survival of the tumor-bearing nude mice was prolonged without obvious toxicity. The dynamic change in cellular uptake, targeted real-time imaging, and the concentration of PTX in the plasma and tumor were all closely associated with the treatment efficacy both in vitro and in vivo. Our study suggests that PTX-NP-anti CA19-9 NPs combined with UMMD is a promising strategy for the treatment of pancreatic cancer.

Affinity capillary electrophoresis and density functional theory study of noncovalent interactions of cyclic peptide [Gly6 ]-antamanide with small cations.

PubMed

Pangavhane, Sachin; Böhm, Stanislav; Makrlík, Emanuel; Ruzza, Paolo; Kašička, Václav

2017-08-01

ACE and density functional theory were employed to study the noncovalent interactions of cyclic decapeptide glycine-6-antamanide ([Gly 6 ]AA), synthetic derivative of native antamanide (AA) peptide from the deadly poisonous fungus Amanita phalloides, with small cations (Li + , Rb + , Cs + , NH 4 + , and Ca 2+ ) in methanol. The strength of these interactions was quantified by the apparent stability constants of the appropriate complexes determined by ACE. The stability constants were calculated using the nonlinear regression analysis of the dependence of the effective electrophoretic mobility of [Gly 6 ]AA on the concentration of the above ions in the BGE (methanolic solution of 20 mM chloroacetic acid, 10 mM Tris, pH MeOH 7.8, containing 0-70 mM concentrations of the above ions added in the form of chlorides). Prior to stability constant calculation, the effective mobilities measured at actual temperature inside the capillary and at variable ionic strength of the BGEs were corrected to the values corresponding to the reference temperature of 25°C and to the constant ionic strength of 10 mM. From the above ions, Rb + and Cs + cations interacted weakly with [Gly 6 ]AA but no interactions of [Gly 6 ]AA with univalent Li + and NH 4 + ions and divalent Ca 2+ ion were observed. The apparent stability constants of [Gly 6 ]AA-Rb + and [Gly 6 ]AA-Cs + complexes were found to be equal to 13 ± 4 and 22 ± 3 L/mol, respectively. The structural characteristics of these complexes, such as position of the Rb + and Cs + ions in the cavity of the [Gly 6 ]AA molecule and the interatomic distances within these complexes, were obtained by the density functional theory calculations. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Neuroimmunological Blood Brain Barrier Opening in Experimental Cerebral Malaria

PubMed Central

Baer, Kerstin; Mikolajczak, Sebastian A.; Kappe, Stefan H. I.; Frevert, Ute

2012-01-01

Plasmodium falciparum malaria is responsible for nearly one million annual deaths worldwide. Because of the difficulty in monitoring the pathogenesis of cerebral malaria in humans, we conducted a study in various mouse models to better understand disease progression in experimental cerebral malaria (ECM). We compared the effect on the integrity of the blood brain barrier (BBB) and the histopathology of the brain of P. berghei ANKA, a known ECM model, P. berghei NK65, generally thought not to induce ECM, P. yoelii 17XL, originally reported to induce human cerebral malaria-like histopathology, and P. yoelii YM. As expected, P. berghei ANKA infection caused neurological signs, cerebral hemorrhages, and BBB dysfunction in CBA/CaJ and Swiss Webster mice, while Balb/c and A/J mice were resistant. Surprisingly, PbNK induced ECM in CBA/CaJ mice, while all other mice were resistant. P. yoelii 17XL and P. yoelii YM caused lethal hyperparasitemia in all mouse strains; histopathological alterations, BBB dysfunction, or neurological signs were not observed. Intravital imaging revealed that infected erythrocytes containing mature parasites passed slowly through capillaries making intimate contact with the endothelium, but did not arrest. Except for relatively rare microhemorrhages, mice with ECM presented no obvious histopathological alterations that would explain the widespread disruption of the BBB. Intravital imaging did reveal, however, that postcapillary venules, but not capillaries or arterioles, from mice with ECM, but not hyperparasitemia, exhibit platelet marginalization, extravascular fibrin deposition, CD14 expression, and extensive vascular leakage. Blockage of LFA-1 mediated cellular interactions prevented leukocyte adhesion, vascular leakage, neurological signs, and death from ECM. The endothelial barrier-stabilizing mediators imatinib and FTY720 inhibited vascular leakage and neurological signs and prolonged survival to ECM. Thus, it appears that neurological signs and coma in ECM are due to regulated opening of paracellular-junctional and transcellular-vesicular fluid transport pathways at the neuroimmunological BBB. PMID:23133375

CSE-MECC two-dimensional capillary electrophoresis analysis of proteins in the mouse tumor cell (AtT-20) homogenate

PubMed Central

Chen, Xingguo; Fazal, Md. Abul; Dovichi, Norman J.

2007-01-01

Two-dimensional capillary electrophoresis was used for the separation of proteins and biogenic amines from the mouse AtT-20 cell line. The first-dimension capillary contained a TRIS-CHES-SDS-dextran buffer to perform capillary sieving electrophoresis, which is based on molecular weight of proteins. The second-dimension capillary contained a TRIS-CHES-SDS buffer for micel1ar electrokinetic capillary chromatography. After a 61 seconds preliminary separation, fractions from the first-dimension capillary were successively transferred to the second-dimension capillary, where they further separated by MECC. The two-dimensional separation required 60 minutes. PMID:17637850

Numerical simulation and stability analysis of solutocapillary effect in ultrathin films

NASA Astrophysics Data System (ADS)

Gordeeva, V. Yu.; Lyushnin, A. V.

2017-04-01

Polar fluids, like water or polydimethylsiloxane, are widely used in technical and medical applications. Capillary effects arising from surface tension gradients can be significant in thin liquid films. The present paper is dedicated to investigation of capillary flow due to a surfactant added to a polar liquid under conditions when intermolecular forces and disjoining pressure play an important role. Evolution equations are formulated for a film profile and the surfactant concentration. Stability analysis shows that the Marangoni effect destabilizes the film, and oscillatory modes appear at slow evaporation rates. We find that the film has four stability modes of at slow evaporation: monotonic stable, monotonic unstable, oscillatory stable, and oscillatory unstable, depending on the wave number of disturbances.

Observation of emission process in hydrogen-like nitrogen Z-pinch discharge with time integrated soft X-ray spectrum pinhole image

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sakai, Y.; Kumai, H.; Nakanishi, Y.

2013-02-15

The emission spectra of hydrogen-like nitrogen Balmer at the wavelength of 13.4 nm in capillary Z-pinch discharge plasma are experimentally examined. Ionization to fully strip nitrogen at the pinch maximum, and subsequent rapid expansion cooling are required to establish the population inversion between the principal quantum number of n = 2 and n = 3. The ionization and recombination processes with estimated plasma parameters are evaluated by utilizing a time integrated spectrum pinhole image containing radial spatial information. A cylindrical capillary plasma is pinched by a triangular pulsed current with peak amplitude of 50 kA and pulse width of 50more » ns.« less

Volcanic emissions from soils at the base of La Fossa volcano, Vulcano island, Italy

NASA Astrophysics Data System (ADS)

Obenholzner, J. H.; Parks, J. L.

2006-12-01

A top-sealed plastic tube with a diameter of ca. 15 cm had been buried vertically at the base of La Fossa volcano, Volcano island, Italy, next to the front of the obsidian flow. The tube had been filled with quartz wool to condense vapors emanating from the soil. At ca. 75 cm below the surface the sample had been exposed to vapors from Sept. 2005 to April 2006. The leached sample had not been in touch with the ground. Another glass wool cushion (ca. 3 cm thick) had been underneath to minimize capillary effects. Leaching of the quartz wool and ICP-MS analysis documented positive values for: Mg, Al, Si, P, K, Ca, Cr, Mn, Ni, Cu, Zn, Cd, Sn, Pb. Leaching with nitric acid documented also V and Fe. Acid leaching produced higher values for all elements, except K and Sn, than leaching with deionized water. Negative values had been obtained for As, Se, Mo. Influence from soil breathing can be excluded as the active fumaroles contain As and Se. This experiment documents for the first time an unknown element transport by vapors/gases through a volcanic edifice interacting with hydrothermal and magmatic gases. It remains unknown if elements detected are entering the atmosphere or are getting adsorbed onto the volcanic ash soil particles derived from reworked surge beds. This question is very important as soils might be an unknown filter medium to filter volcanically polluted air in case of major volcanic crises. Data can be obtained from the authors.

Synthesis of Hydroxy-Terminated Dinitropropyl Acrylate Polymers and Improved Characterization of Hydroxy-Terminated Prepolymers

DTIC Science & Technology

1983-03-01

Carbonate GPC Gel Permeation Chromatography HEDS Hydroxyethyl Disulfide HPLC High Pressure Liquid Chromatography NMIM N-methyl imidazole NPGA Neopentyl... analysis and intrinsic viscosity determination by a capillary viscometry shows promise as a reliable approach for the determination of the molecular...more reliable and meaningful data than GPC analysis alone. 3.2.3 Determination of Number Average Functionality of Prepolymer of fp < 2.0 The number

Mobile, Multi-modal, Label-Free Imaging Probe Analysis of Choroidal Oximetry and Retinal Hypoxia

DTIC Science & Technology

2015-10-01

eyes and image choroidal vessels/capillaries using CARS intravital microscopy Subtask 3: Measure oxy-hemoglobin levels in PBI test and control eyes...AWARD NUMBER: W81XWH-14-1-0537 TITLE: Mobile, Multi-modal, Label-Free Imaging Probe Analysis of Choroidal Oximetry and Retinal Hypoxia...4. TITLE AND SUBTITLE Mobile, Multimodal, Label-Free Imaging Probe Analysis of Choroidal Oximetry and Retinal Hypoxia 5a. CONTRACT NUMBER W81XWH

77 FR 53212 - Federal Property Suitable as Facilities To Assist the Homeless

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-31

... Buildings Duplex Cabins Yosemite CA 95389 Landholding Agency: Interior Property Number: 61201230009 Status... details 33 Buildings Duplex Cabins Yosemite CA 95389 Landholding Agency: Interior Property Number...

Effect of running exercise on the number of the neurons in the hippocampus of young transgenic APP/PS1 mice.

PubMed

Jiang, Lin; Ma, Jing; Zhang, Yi; Zhou, Chun-Ni; Zhang, Lei; Chao, Feng-Lei; Chen, Lin-Mu; Jiang, Rong; Wu, Hong; Tang, Yong

2018-08-01

To investigate the effect of running exercise on the number of the neurons in the hippocampus of young APP/PS1 mice, twenty 6-month-old male APP/ PS1 transgenic mice were randomly divided into the APP/PS1 control (AD control) group and the APP/PS1 running (AD running) group (10 mice per group), and ten wild-type mice of the littermate were regarded as the wild-type (WT) group. The AD running mice ran on motorized treadmill machiene for 4 months, while the WT mice and AD control mice were housed in standard condition without running. Then, Morris water maze tests (MWM) were used to assess the special learning and memory abilities of mice in three groups. The stereological methods were used to quantitatively evaluate the volume of the hippocampus, CA1/2, CA3 and the dentate gyrus (DG) and count the number of the neurons in CA1/2, CA3 and DG. We found that 4-month running effectively shortened the escape latency of young APP/PS1 control mice in MWM. More importantly, 4-month running effectively increased the volumes of the hippocampus, CA1/2, CA3 and DG and increased the number of neurons in CA1/2, CA3 and DG in young APP/PS1 mice. The present results suggested that 4-month running has significant beneficial effects on the spatial learning and memory capacities of young APP/PS1 mice and could delay the progress of atrophy of hippocampus and the neuron death in CA1/2, CA3 and DG in young APP/PS1 mice. Copyright © 2018 Elsevier B.V. All rights reserved.

The impact of automatic devices for capillary blood collection on efficiency and pain response in newborns: A randomized controlled trial.

PubMed

Sorrentino, G; Fumagalli, M; Milani, S; Cortinovis, I; Zorz, A; Cavallaro, G; Mosca, F; Plevani, L

2017-07-01

The heel stick is the method of choice in most neonatal units for capillary blood sampling, and it represents the most common event among all painful procedures performed on newborns. The type and design of heel stick device and the clinical procedure to collect a blood sample may have an impact on newborn pain response as well. To compare the pain response and efficiency of different automated devices for capillary blood collection in newborns. Randomized clinical trial. Postnatal ward of a tertiary-care university hospital in Italy. Newborn infants at gestational age ≥34 weeks undergoing the metabolic screening test after the 49th hour of life. A total of 762 neonates were recruited and randomized into 6 groups (127 babies in each group) assigned to 6 different capillary blood collection devices (Ames Minilet™ Lancet; Cardinal Health Gentleheel ® ; Natus Medical NeatNick™; BD Quikheel™ Lancet; Vitrex Steriheel ® Baby Lancet; Accriva Diagnostics Tenderfoot ® ). The following data were collected and assessed for each of the 6 groups evaluated: a) number of heel sticks, b) pain score according to the Neonatal Infant Pain Scale (NIPS) and c) need to squeeze the heel. The Ames Minilet™ Lancet device was found to perform by far the worst compared to the five device underexamination: it required the highest number of sticks (mean=3.91; 95% CI: 3.46-4.36), evoked the most intense pain (mean=3.98; 95% CI: 3.77-4.20), and most frequently necessitated squeezing the heel (92.9%; 95% CI: 86.9-96.3). The five devices under examination appeared to be similar in terms of the number of sticks required, but differed slightly in NIPS score and in need to squeeze the heel. The Accriva Diagnostics Tenderfoot ® device demonstrated the greatest efficiency for blood sampling and evoked the least pain. With this device, the metabolic screening test could be performed with a single skin incision in the large majority of infants (98.4%), heel squeezing was limited to only 6.3% of infants, and the NIPS score turns out to be lower than other devices in our study (1.22; 95% CI 1.05-1.39). Copyright © 2017 Elsevier Ltd. All rights reserved.

Insulin-induced changes in microvascular vasomotion and capillary recruitment are associated in humans.

PubMed

de Boer, Michiel P; Meijer, Rick I; Newman, John; Stehouwer, Coen D A; Eringa, Etto C; Smulders, Yvo M; Serné, Erik H

2014-07-01

Insulin-induced capillary recruitment is considered a significant regulator of overall insulin-stimulated glucose uptake. Insulin's action to recruit capillaries has been hypothesized to involve insulin-induced changes in vasomotion. Data directly linking vasomotion to capillary perfusion, however, are presently lacking. We, therefore, investigated whether insulin's actions on capillary recruitment and vasomotion were interrelated in a group of healthy individuals. We further assessed the role of capillary recruitment in the association between vasomotion and insulin-mediated glucose uptake. Changes in vasomotion and capillary density were determined by LDF and capillary videomicroscopy in skin, respectively, before and during a hyperinsulinemic euglycemic clamp in 19 healthy volunteers. Insulin-induced increase in the neurogenic vasomotion domain was positively related to insulin-augmented capillary recruitment (r = 0.51, p = 0.04), and both parameters were related to insulin-mediated glucose uptake (r = 0.47, p = 0.06 and r = 0.73, p = 0.001, respectively). The change in insulin-augmented capillary recruitment could, at least statistically, largely explain the association between the neurogenic domain and insulin-mediated glucose uptake. Insulin-induced changes in vasomotion and capillary recruitment are associated in healthy volunteers. These data suggest that insulin's action to recruit capillaries may in part involve action on the neurogenic vasomotion domain, thereby enhancing capillary perfusion and glucose uptake. © 2014 John Wiley & Sons Ltd.

Formation of self-organized nanoporous anodic oxide from metallic gallium.

PubMed

Pandey, Bipin; Thapa, Prem S; Higgins, Daniel A; Ito, Takashi

2012-09-25

This paper reports the formation of self-organized nanoporous gallium oxide by anodization of solid gallium metal. Because of its low melting point (ca. 30 °C), metallic gallium can be shaped into flexible structures, permitting the fabrication of nanoporous anodic oxide monoliths within confined spaces like the inside of a microchannel. Here, solid gallium films prepared on planar substrates were employed to investigate the effects of anodization voltage (1, 5, 10, 15 V) and H(2)SO(4) concentration (1, 2, 4, 6 M) on anodic oxide morphology. Self-organized nanopores aligned perpendicular to the film surface were obtained upon anodization of gallium films in ice-cooled 4 and 6 M aqueous H(2)SO(4) at 10 and 15 V. Nanopore formation could be recognized by an increase in anodic current after a current decrease reflecting barrier oxide formation. The average pore diameter was in the range of 18-40 nm with a narrow diameter distribution (relative standard deviation ca. 10-20%), and was larger at lower H(2)SO(4) concentration and higher applied voltage. The maximum thickness of nanoporous anodic oxide was ca. 2 μm. In addition, anodic formation of self-organized nanopores was demonstrated for a solid gallium monolith incorporated at the end of a glass capillary. Nanoporous anodic oxide monoliths formed from a fusible metal will lead to future development of unique devices for chemical sensing and catalysis.

Monitoring of peri-distal gastrectomy carbohydrate antigen 19-9 level in gastric juice and its significance

PubMed Central

Xu, A-Man; Huang, Lei; Han, Wen-Xiu; Wei, Zhi-Jian

2014-01-01

Gastric carcinoma is one of the most common and deadly malignancies nowadays, and carbohydrate antigen 19-9 (CA 19-9) in gastric juice has been rarely studied. To compare peri-distal gastrectomy (DG) gastric juice and serum CA 19-9 and reveal its significance, we selected 67 patients diagnosed with gastric carcinoma who underwent DG, and collected their perioperative gastric juice whose CA 19-9 was detected, with serum CA 19-9 monitored as a comparison. We found that: gastric juice CA 19-9 pre-gastrectomy was significantly correlated with tumor TNM classification, regarding tumor size, level of gastric wall invaded, differentiated grade and number of metastatic lymph nodes as influencing factors, while serum CA 19-9 revealed little information; gastric juice CA 19-9 was significantly correlated with radical degree, and regarded number of resected lymph nodes and classification of cutting edge as impact factors; thirteen patients whose gastric juice CA 19-9 rose post-DG showed features indicating poor prognosis; the difference of gastric juice CA 19-9 between pre- and post-gastrectomy was correlated with tumor TNM classification and radical degree, and regarded tumor size, number of resected metastatic and normal lymph nodes, sum of distances from tumor to cutting edges and classification of cutting edge as influential factors. We conclude that peri-DG gastric juice CA 19-9 reveals much information about tumor and radical gastrectomy, and may indicate prognosis; while serum CA 19-9 has limited significance. PMID:24482710

[Interaction of human factor X with thromboplastin].

PubMed

Kiselev, S V; Zubairov, D M; Timarbaev, V N

2003-01-01

The binding of 125I-labeled human factor X to native and papaine-treated tissue tromboplastin in the presence of CaCl2 or EDTA was studied. The Scatchard analysis suggests the existence of high (Kd=l,8 x10(-9) M) and low affinity binding sites on the thromboplastin surface. The removal of Ca2+ reduced affinity of factor X to the high affinity sites. This was accompanied by some increase of their number. Proteolysis by papaine decreased affinity of high affinity sites and caused the increase of their number in the presence of Ca2+. In the absence of Ca2+ the affinity remained unchanged, but the number of sites decreased. At low concentrations of factor X positive cooperativity for high affinity binding sites was observed. It did not depend on the presence of Ca2+. The results indirectly confirm the role of hydrophobic interactons in Ca2+ dependent binding of factor X to thromboplastin and the fact that heterogeneity of this binding is determined by mesophase structure of the thromboplastin phospholipids.

Effect of Capillary Tube’s Shape on Capillary Rising Regime for Viscos Fluids

NASA Astrophysics Data System (ADS)

Soroush, F.; Moosavi, A.

2018-05-01

When properties of the displacing fluid are considered, the rising profile of the penetrating fluid in a capillary tube deviates from its classical Lucas-Washburn profile. Also, shape of capillary tube can affect the rising profile in different aspects. In this article, effect of capillary tube’s shape on the vertical capillary motion in presence of gravity is investigated by considering the properties of the displacing fluid. According to the fact that the differential equation of the capillary rising for a non-simple wall type is very difficult to solve analytically, a finite element simulation model is used for this study. After validation of the simulation model with an experiment that has been done with a simple capillary tube, shape of the capillary tube’s wall is changed in order to understand its effects on the capillary rising and different motion regimes that may appear according to different geometries. The main focus of this article is on the sinusoidal wall shapes and comparing them with a simple wall.

Means and method for capillary zone electrophoresis with laser-induced indirect fluorescence detection

DOEpatents

Yeung, Edward S.; Kuhr, Werner G.

1996-02-20

A means and method for capillary zone electrphoresis with laser-induced indirect fluorescence detection. A detector is positioned on the capillary tube of a capillary zone electrophoresis system. The detector includes a laser which generates a laser beam which is imposed upon a small portion of the capillary tube. Fluorescence of the elutant electromigrating through the capillary tube is indirectly detected and recorded.

Means and method for capillary zone electrophoresis with laser-induced indirect fluorescence detection

DOEpatents

Yeung, Edwards; Kuhr, Werner G.

1991-04-09

A means and method for capillary zone electrphoresis with laser-induced indirect fluorescence detection. A detector is positioned on the capillary tube of a capillary zone electrophoresis system. The detector includes a laser which generates a laser beam which is imposed upon a small portion of the capillary tube. Fluorescence of the elutant electromigrating through the capillary tube is indirectly detected and recorded.

Enhancing separation in short-capillary electrophoresis via pressure-driven backflow.

PubMed

Tian, Miaomiao; Wang, Yujia; Mohamed, Amara Camara; Guo, Liping; Yang, Li

2015-07-01

We present a novel easy-to-operate and efficient method to improve the separation efficiency in short-capillary electrophoresis by introducing steady backflow to counterbalance electro-osmotic flow without the use of any external pressure. The backflow was easily generated by tapering the capillary end, which was achieved by heating a straight capillary and stretching it with a constant force. We investigated the net fluidic transport rate under different tip lengths and separation voltages. Good run-to-run repeatability and capillary-to-capillary reproducibility of the present method were obtained with RSD less than 1.5%, indicating the stability of the fluid transport rate in the tapered capillary, which ensures the quantification and repeatability of capillary zone electrophoresis (CZE) analysis. Enhanced separation of the tapered short capillary electrophoresis was demonstrated by CZE analyzing amino acids and positional isomers. Baseline separations were achieved in less than 60 s using a tapered capillary with the effective length of 5 cm, while no separation was achieved using a normal capillary without a tapered tip. The present study provides a promising method to use pressure-driven backflow to enhance separation efficiency in short-capillary electrophoresis, which would be of potential value in a wide application for fast analysis of complex samples. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Measurement of Capillary Radius and Contact Angle within Porous Media.

PubMed

Ravi, Saitej; Dharmarajan, Ramanathan; Moghaddam, Saeed

2015-12-01

The pore radius (i.e., capillary radius) and contact angle determine the capillary pressure generated in a porous medium. The most common method to determine these two parameters is through measurement of the capillary pressure generated by a reference liquid (i.e., a liquid with near-zero contact angle) and a test liquid. The rate of rise technique, commonly used to determine the capillary pressure, results in significant uncertainties. In this study, we utilize a recently developed technique for independently measuring the capillary pressure and permeability to determine the equivalent minimum capillary radii and contact angle of water within micropillar wick structures. In this method, the experimentally measured dryout threshold of a wick structure at different wicking lengths is fit to Darcy's law to extract the maximum capillary pressure generated by the test liquid. The equivalent minimum capillary radii of different wick geometries are determined by measuring the maximum capillary pressures generated using n-hexane as the working fluid. It is found that the equivalent minimum capillary radius is dependent on the diameter of pillars and the spacing between pillars. The equivalent capillary radii of micropillar wicks determined using the new method are found to be up to 7 times greater than the current geometry-based first-order estimates. The contact angle subtended by water at the walls of the micropillars is determined by measuring the capillary pressure generated by water within the arrays and the measured capillary radii for the different geometries. This mean contact angle of water is determined to be 54.7°.

Experiments on the Effects of Confining Pressure During Reaction-Driven Cracking

NASA Astrophysics Data System (ADS)

Skarbek, R. M.; Savage, H. M.; Kelemen, P. B.; Lambart, S.; Robinson, B.

2016-12-01

Cracking caused by reaction-driven volume increase is an important process in many geological settings. In particular, the interaction of brittle rocks with reactive fluids can create fractures that modify the permeability and reactive surface area, leading to a large variety of feedbacks. The conditions controlling reaction-driven cracking are poorly understood, especially at geologically relevant confining pressures. We conducted two sets of experiments to study the effects of confining pressure on cracking during the formation of gypsum from anhydrite CaSO4 + 2H2O = CaSO4•2H2O, and portlandite from calcium oxide CaO + H2O = Ca(OH)2. In the first set of experiments, we cold-pressed CaSO4, or CaO powder to form cylinders. Samples were confined in steel, and compressed with an axial load of 0.1 to 4 MPa. Water was allowed to infiltrate the initially unsaturated samples through the bottom face via capillary and Darcian flow across a micro-porous frit. The height of the sample was recorded during the experiment, and serves as a measure of volume change due to the hydration reaction. We also recorded acoustic emissions (AEs) using piezoelectric transducers (PZTs), to serve as a measure of cracking during an experiment. Experiments were stopped when the recorded volume change reached 80% - 100% of the stoichiometrically calculated volume change of the reaction. In a second set of experiments, we pressed CaSO4 powder to form cylinders 8.9 cm in length and 3.5 cm in diameter for testing in a tri-axial press with ports for fluid input and output, across the top and bottom faces of the sample. The tri-axial experiments were set up to investigate the reaction-driven cracking process for a range of confining pressures. Cracking during experiments was monitored using strain gauges and PZTs attached to the sample. We measured permeability during experiments by imposing a fluid pressure gradient across the sample. These experiments elucidate the role of cracking caused by crystallization pressure in many important hydration reactions.

Renal Autoregulation in Health and Disease

PubMed Central

Carlström, Mattias; Wilcox, Christopher S.; Arendshorst, William J.

2015-01-01

Intrarenal autoregulatory mechanisms maintain renal blood flow (RBF) and glomerular filtration rate (GFR) independent of renal perfusion pressure (RPP) over a defined range (80–180 mmHg). Such autoregulation is mediated largely by the myogenic and the macula densa-tubuloglomerular feedback (MD-TGF) responses that regulate preglomerular vasomotor tone primarily of the afferent arteriole. Differences in response times allow separation of these mechanisms in the time and frequency domains. Mechanotransduction initiating the myogenic response requires a sensing mechanism activated by stretch of vascular smooth muscle cells (VSMCs) and coupled to intracellular signaling pathways eliciting plasma membrane depolarization and a rise in cytosolic free calcium concentration ([Ca2+]i). Proposed mechanosensors include epithelial sodium channels (ENaC), integrins, and/or transient receptor potential (TRP) channels. Increased [Ca2+]i occurs predominantly by Ca2+ influx through L-type voltage-operated Ca2+ channels (VOCC). Increased [Ca2+]i activates inositol trisphosphate receptors (IP3R) and ryanodine receptors (RyR) to mobilize Ca2+ from sarcoplasmic reticular stores. Myogenic vasoconstriction is sustained by increased Ca2+ sensitivity, mediated by protein kinase C and Rho/Rho-kinase that favors a positive balance between myosin light-chain kinase and phosphatase. Increased RPP activates MD-TGF by transducing a signal of epithelial MD salt reabsorption to adjust afferent arteriolar vasoconstriction. A combination of vascular and tubular mechanisms, novel to the kidney, provides for high autoregulatory efficiency that maintains RBF and GFR, stabilizes sodium excretion, and buffers transmission of RPP to sensitive glomerular capillaries, thereby protecting against hypertensive barotrauma. A unique aspect of the myogenic response in the renal vasculature is modulation of its strength and speed by the MD-TGF and by a connecting tubule glomerular feedback (CT-GF) mechanism. Reactive oxygen species and nitric oxide are modulators of myogenic and MD-TGF mechanisms. Attenuated renal autoregulation contributes to renal damage in many, but not all, models of renal, diabetic, and hypertensive diseases. This review provides a summary of our current knowledge regarding underlying mechanisms enabling renal autoregulation in health and disease and methods used for its study. PMID:25834230

Acupuncture attenuates cognitive deficits and increases pyramidal neuron number in hippocampal CA1 area of vascular dementia rats.

PubMed

Li, Fang; Yan, Chao-Qun; Lin, Li-Ting; Li, Hui; Zeng, Xiang-Hong; Liu, Yi; Du, Si-Qi; Zhu, Wen; Liu, Cun-Zhi

2015-04-28

Decreased cognition is recognized as one of the most severe and consistent behavioral impairments in dementia. Experimental studies have reported that acupuncture may improve cognitive deficits, relieve vascular dementia (VD) symptoms, and increase cerebral perfusion and electrical activity. Multi-infarction dementia was modeled in rats with 3% microemboli saline suspension. Two weeks after acupuncture at Zusanli (ST36), all rats were subjected to a hidden platform trial to test their 3-day spatial memory using the Morris water maze test. To estimate the numbers of pyramidal neuron, astrocytes, and synaptic boutons in hippocampal CA1 area, we adopted an unbiased stereology method to accurately sample and measure the size of cells. We found that acupuncture at ST36 significantly decreased the escape latency of VD rats. In addition, acupuncture significantly increased the pyramidal neuron number in hippocampal CA1 area (P < 0.05) and tended to decrease the number of astrocytes (P = 0.063). However, there was no significant change in the synaptic bouton number of hippocampal CA1 area in any of the groups (P > 0.05). These findings suggest that acupuncture may improve cognitive deficits and increase pyramidal neuron number of hippocampal CA1 area in VD rats.

A capillary electrophoresis method to explore the self-assembly of a novel polypeptide ligand with quantum dots.

PubMed

Wang, Jianhao; Zhang, Chencheng; Liu, Li; Kalesh, Karunakaran A; Qiu, Lin; Ding, Shumin; Fu, Minli; Gao, Li-Qian; Jiang, Pengju

2016-08-01

Polyhistidine peptides are effective ligands to coat quantum dots (QDs). It is known that both the number of histidine (His) residues repeats and their structural arrangements in a peptide ligand play important roles in the assembly of the peptide onto CdSe/ZnS QDs. However, due to steric hindrance, a peptide sequence with more than six His residue tandem repeats would hardly coordinate well with Zn(2+) in the QD shell to further enhance the binding affinity. To solve this problem, a His-containing peptide ligand, ATTO 590-E2 G (NH)6 (ATTO-NH), was specifically designed and synthesized for assembly with QDs. With sequential injection of QDs and ATTO-NH into the capillary electrophoresis with fluorescence detection, strong Förster resonance energy transfer phenomenon between the QDs and the ATTO 590 dye was observed, indicating efficient self-assembly of the novel peptide onto the QDs to form ATTO-NH capped QDs inside the capillary. The binding stability of the ligand onto the QD was then systematically investigated by titrating with imidazole, His, and a his-tag containing competitive peptide. It is believed that this new in-capillary assay significantly reduced the sample consumption and the analysis time. By functionalizing QDs with certain metal cation-specific group fused peptide ligand, the QD-based probes could be even extended to the online detection of metal cations for monitoring environment in the future. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Jet dynamics post drop impact on a deep pool

NASA Astrophysics Data System (ADS)

Michon, Guy-Jean; Josserand, Christophe; Séon, Thomas

2017-02-01

We investigate experimentally the jet formed by the collapse of a cavity created by the impact of a drop on a pool of the same aqueous liquid. We show that jets can emerge with very different shapes and velocities, depending on the impact parameters, thus generating droplets with various initial sizes and velocities. After presenting the jet velocity and top drop radius variation as a function of the impact parameters, we discuss the influence of the liquid parameters on the jet velocity. This allows us to define two different regimes: the singular jet and the cavity jet regimes, where the mechanisms leading to the cavity retraction and subsequent jet dynamics are drastically different. In particular, we demonstrate that in the first regime, a singular capillary wave collapse sparks the whole jet dynamics, making the jet's fast, thin, liquid parameters dependent and barely reproducible. On the contrary, in the cavity jet regime, defined for higher impact Froude numbers, the jets are fat and slow. We show that jet velocity is simply proportional to the capillary velocity √{γ /ρlDd }, where γ is the liquid surface tension, ρl the liquid density, and Dd the impacting drop diameter, and it is in particular independent of viscosity, impact velocity, and gravity, even though the cavity is larger than the capillary length. Finally, we demonstrate that capillary wave collapse and cavity retraction are correlated in the singular regime and decorrelated in the cavity jet regime.

Simultaneous detection of genetically modified organisms by multiplex ligation-dependent genome amplification and capillary gel electrophoresis with laser-induced fluorescence.

PubMed

García-Cañas, Virginia; Mondello, Monica; Cifuentes, Alejandro

2010-07-01

In this work, an innovative method useful to simultaneously analyze multiple genetically modified organisms is described. The developed method consists in the combination of multiplex ligation-dependent genome dependent amplification (MLGA) with CGE and LIF detection using bare-fused silica capillaries. The MLGA process is based on oligonucleotide constructs, formed by a universal sequence (vector) and long specific oligonucleotides (selectors) that facilitate the circularization of specific DNA target regions. Subsequently, the circularized target sequences are simultaneously amplified with the same couple of primers and analyzed by CGE-LIF using a bare-fused silica capillary and a run electrolyte containing 2-hydroxyethyl cellulose acting as both sieving matrix and dynamic capillary coating. CGE-LIF is shown to be very useful and informative for optimizing MLGA parameters such as annealing temperature, number of ligation cycles, and selector probes concentration. We demonstrate the specificity of the method in detecting the presence of transgenic DNA in certified reference and raw commercial samples. The method developed is sensitive and allows the simultaneous detection in a single run of percentages of transgenic maize as low as 1% of GA21, 1% of MON863, and 1% of MON810 in maize samples with signal-to-noise ratios for the corresponding DNA peaks of 15, 12, and 26, respectively. These results demonstrate, to our knowledge for the first time, the great possibilities of MLGA techniques for genetically modified organisms analysis.

Ion guiding in macro-size insulating capillaries: straight, tapered, and curved shapes

NASA Astrophysics Data System (ADS)

Kojima, Takao M.

2018-02-01

When keV energy ions are injected into a tilted insulating capillary, a certain fraction of the injected ions are transported through the tilt angle of the capillary. This ion guiding phenomenon is considered to be caused by a self-organizing charge distribution, where the inner wall of the capillary becomes charged by initial incoming ions. The charge distribution, which is formed, can guide following ions toward the exit of the capillary. Since the initial discovery of this effect, studies of ion guiding by insulating capillaries have been extended to various materials, and different sizes and shapes of capillaries. In recent years, some investigations of the guiding effect of macro-size curved capillaries have also been reported. In this review, relevant studies in a history of ion guiding in curved capillaries are discussed and future directions in this field are considered.

High-speed video capillaroscopy method for imaging and evaluation of moving red blood cells

NASA Astrophysics Data System (ADS)

Gurov, Igor; Volkov, Mikhail; Margaryants, Nikita; Pimenov, Aleksei; Potemkin, Andrey

2018-05-01

The video capillaroscopy system with high image recording rate to resolve moving red blood cells with velocity up to 5 mm/s into a capillary is considered. Proposed procedures of the recorded video sequence processing allow evaluating spatial capillary area, capillary diameter and central line with high accuracy and reliability independently on properties of individual capillary. Two-dimensional inter frame procedure is applied to find lateral shift of neighbor images in the blood flow area with moving red blood cells and to measure directly the blood flow velocity along a capillary central line. The developed method opens new opportunities for biomedical diagnostics, particularly, due to long-time continuous monitoring of red blood cells velocity into capillary. Spatio-temporal representation of capillary blood flow is considered. Experimental results of direct measurement of blood flow velocity into separate capillary as well as capillary net are presented and discussed.

Automated Parallel Capillary Electrophoretic System

DOEpatents

Li, Qingbo; Kane, Thomas E.; Liu, Changsheng; Sonnenschein, Bernard; Sharer, Michael V.; Kernan, John R.

2000-02-22

An automated electrophoretic system is disclosed. The system employs a capillary cartridge having a plurality of capillary tubes. The cartridge has a first array of capillary ends projecting from one side of a plate. The first array of capillary ends are spaced apart in substantially the same manner as the wells of a microtitre tray of standard size. This allows one to simultaneously perform capillary electrophoresis on samples present in each of the wells of the tray. The system includes a stacked, dual carousel arrangement to eliminate cross-contamination resulting from reuse of the same buffer tray on consecutive executions from electrophoresis. The system also has a gel delivery module containing a gel syringe/a stepper motor or a high pressure chamber with a pump to quickly and uniformly deliver gel through the capillary tubes. The system further includes a multi-wavelength beam generator to generate a laser beam which produces a beam with a wide range of wavelengths. An off-line capillary reconditioner thoroughly cleans a capillary cartridge to enable simultaneous execution of electrophoresis with another capillary cartridge. The streamlined nature of the off-line capillary reconditioner offers the advantage of increased system throughput with a minimal increase in system cost.

Fluid Delivery System For Capillary Electrophoretic Applications.

DOEpatents

Li, Qingbo; Liu, Changsheng; Kane, Thomas E.; Kernan, John R.; Sonnenschein, Bernard; Sharer, Michael V.

2002-04-23

An automated electrophoretic system is disclosed. The system employs a capillary cartridge having a plurality of capillary tubes. The cartridge has a first array of capillary ends projecting from one side of a plate. The first array of capillary ends are spaced apart in substantially the same manner as the wells of a microtitre tray of standard size. This allows one to simultaneously perform capillary electrophoresis on samples present in each of the wells of the tray. The system includes a stacked, dual carrousel arrangement to eliminate cross-contamination resulting from reuse of the same buffer tray on consecutive executions from electrophoresis. The system also has a gel delivery module containing a gel syringe/a stepper motor or a high pressure chamber with a pump to quickly and uniformly deliver gel through the capillary tubes. The system further includes a multi-wavelength beam generator to generate a laser beam which produces a beam with a wide range of wavelengths. An off-line capillary reconditioner thoroughly cleans a capillary cartridge to enable simultaneous execution of electrophoresis with another capillary cartridge. The streamlined nature of the off-line capillary reconditioner offers the advantage of increased system throughput with a minimal increase in system cost.

An Electrochemical Investigation of the Chemical Diffusivity in Liquid Metal Alloys

NASA Astrophysics Data System (ADS)

Barriga, Salvador A.

The liquid metal battery has been shown to be a viable candidate for grid-scale energy storage, due to its fast kinetics and ability to be constructed from economically feasible materials. Various of the liquid metal couples that form high stable voltages, such as the calcium chemistries, are rate limited because they tend to form solid intermetallic compounds with high melting points. In order to understand and better engineer these batteries, the kinetic properties of these liquid alloys, in particular the chemical diffusivity, must be known accurately so that it can be used as input in computational simulations to avoid the nucleation of any solids. Unfortunately, the dominant experimental methods for measuring diffusion in liquid metals today are unreliable because the measurement timescales are on the order of days, require long capillaries susceptible to buoyancy-driven flow from temperature fluctuations, and composition analysis must be done ex-situ as a solid. To counter all these problems, a new and novel method for measuring the chemical diffusivity of metals in liquid alloys derived from electrochemical principles is presented in this thesis. This new method has the advantage of operating in shorter times scales of minutes rather than days, and requires the use of small capillaries which collectively minimize the effect of convectively-driven flow caused from temperature gradients. This new method was derived by solving the same boundary conditions required by the galvanostatic intermittent titration technique for solid-state electrodes. To verify the validity of the new theoretical derivation, the method was used to measure the chemical diffusivity of calcium in liquid bismuth within the temperature range of 550 - 700 °C using a three-electrode setup with a ternary molten salt electrolyte. Three compositions where studied (5% Ca-Bi, 10% Ca-Bi, and 15% Ca-Bi) for comparison. The chemical diffusion coefficient was found to range between (6.77 +/- 0.21)x10-5 cm2/s - (10.9 +/- 0.21 )x10-5 cm2/s at 5% Ca-Bi, (4.95 +/- 0.65)x10-5 cm2/s - (7.93 +/- 0.37)x10 -5 cm2/s at 10% Ca-Bi, and (6.22 +/- 1.2)x10 -5 cm2/s- (10.2 +/- 0.26)x10-5 cm2/s at 15% Ca-Bi which, to our knowledge, are the first successful measurements of calcium diffusivity in the liquid state. Arrhenius fits with good correlations revealed the activation energy for diffusion to be (21.4+/-1.7) kJ/mol, (23 .0+/-2.4) kJ/mol, and (17.7+/-5.9) kJ/mol as the calcium concentration increased, which are in excellent agreement with literature published values and lie in the same range of 15-30 kJ/mol that is reported for most liquid metals. The chemical diffusivity value was then used as input in finite element simulations to model how convection affects the overall transport inside a 20-Ah liquid bismuth electrode under the influence of different thermal boundary conditions. Also, a phase field model was created to simulate the motion of the two interfaces inside a liquid metal battery during operation, which to our knowledge, is the first time phase field has been extended beyond two phases. Experimental kinetic values can then be used as input in these numerical models to help characterize and optimize the entire battery. (Copies available exclusively from MIT Libraries, libraries.mit.edu/docs - docs mit.edu)

Reaction of Chlorosulfonyl Isocyanate (CSI) with Fluorosubstituted Alkenes: Evidence of a Concerted Pathway for Reaction of CSI with Fluorosubstituted Alkenes (Preprint)

DTIC Science & Technology

2010-06-01

REPORT NUMBER ir Force Research Laboratory (AFMC) AFRL/RZSP 10 E. Saturn Blvd. Edwards AFB CA 93524-7680 AFRL-RZ-ED-JA-2010-282 9...MONITOR’S 5 Pollux Drive NUMBER(S) Edwards AFB CA 93524-70448 AFRL-RZ-ED-JA-2010-282 12. DISTRIBUTION / AVAILABILITY STATEMENT Approved...Boatz§, Arnold L. Reingold± and Curtis E. Moore±. ≠Department of Chemistry, Point Loma Nazarene University, San Diego, CA . 92106-2899 §Air Force

VizieR Online Data Catalog: Empirical calibration of the near-IR Ca triplet (Cenarro+ 2001)

NASA Astrophysics Data System (ADS)

Cenarro; A. J.; Cardiel; N.; Gorgas; J.; Peletier; R. F.; Vazdekis; A.; Prada; F.

2001-09-01

File table contains details of the new near-IR stellar library observed to calibrate the Ca II triplet. It includes the indices CaT*, CaT and PaT measured over the final spectra as well as their corresponding errors. The Henry Draper Catalogue number, other names (mainly HR and BD numbers), coordinates, spectral type, luminosity class, apparent magnitude and atmospheric parameters (as derived in Paper II; Cenarro et al., 2001MNRAS.326..981C) are also given. (1 data file).

How many taxa can be recognized within the complex Tillandsia capillaris (Bromeliaceae, Tillandsioideae)? Analysis of the available classifications using a multivariate approach.

PubMed

Castello, Lucía V; Galetto, Leonardo

2013-01-01

Tillandsia capillaris Ruiz & Pav., which belongs to the subgenus Diaphoranthema is distributed in Ecuador, Peru, Bolivia, northern and central Argentina, and Chile, and includes forms that are difficult to circumscribe, thus considered to form a complex. The entities of this complex are predominantly small-sized epiphytes, adapted to xeric environments. The most widely used classification defines 5 forms for this complex based on few morphological reproductive traits: Tillandsia capillaris Ruiz & Pav. f. capillaris, Tillandsia capillaris f. incana (Mez) L.B. Sm., Tillandsia capillaris f. cordobensis (Hieron.) L.B. Sm., Tillandsia capillaris f. hieronymi (Mez) L.B. Sm. and Tillandsia capillaris f. virescens (Ruiz & Pav.) L.B. Sm. In this study, 35 floral and vegetative characters were analyzed with a multivariate approach in order to assess and discuss different proposals for classification of the Tillandsia capillaris complex, which presents morphotypes that co-occur in central and northern Argentina. To accomplish this, data of quantitative and categorical morphological characters of flowers and leaves were collected from herbarium specimens and field collections and were analyzed with statistical multivariate techniques. The results suggest that the last classification for the complex seems more comprehensive and three taxa were delimited: Tillandsia capillaris (=Tillandsia capillaris f. incana-hieronymi), Tillandsia virescens s. str. (=Tillandsia capillaris f. cordobensis) and Tillandsia virescens s. l. (=Tillandsia capillaris f. virescens). While Tillandsia capillaris and Tillandsia virescens s. str. co-occur, Tillandsia virescens s. l. is restricted to altitudes above 2000 m in Argentina. Characters previously used for taxa delimitation showed continuous variation and therefore were not useful. New diagnostic characters are proposed and a key is provided for delimiting these three taxa within the complex.

How many taxa can be recognized within the complex Tillandsia capillaris (Bromeliaceae, Tillandsioideae)? Analysis of the available classifications using a multivariate approach

PubMed Central

Castello, Lucía V.; Galetto, Leonardo

2013-01-01

Abstract Tillandsia capillaris Ruiz & Pav., which belongs to the subgenus Diaphoranthema is distributed in Ecuador, Peru, Bolivia, northern and central Argentina, and Chile, and includes forms that are difficult to circumscribe, thus considered to form a complex. The entities of this complex are predominantly small-sized epiphytes, adapted to xeric environments. The most widely used classification defines 5 forms for this complex based on few morphological reproductive traits: Tillandsia capillaris Ruiz & Pav. f. capillaris, Tillandsia capillaris f. incana (Mez) L.B. Sm., Tillandsia capillaris f. cordobensis (Hieron.) L.B. Sm., Tillandsia capillaris f. hieronymi (Mez) L.B. Sm. and Tillandsia capillaris f. virescens (Ruiz & Pav.) L.B. Sm. In this study, 35 floral and vegetative characters were analyzed with a multivariate approach in order to assess and discuss different proposals for classification of the Tillandsia capillaris complex, which presents morphotypes that co-occur in central and northern Argentina. To accomplish this, data of quantitative and categorical morphological characters of flowers and leaves were collected from herbarium specimens and field collections and were analyzed with statistical multivariate techniques. The results suggest that the last classification for the complex seems more comprehensive and three taxa were delimited: Tillandsia capillaris (=Tillandsia capillaris f. incana-hieronymi), Tillandsia virescens s. str. (=Tillandsia capillaris f. cordobensis) and Tillandsia virescens s. l. (=Tillandsia capillaris f. virescens). While Tillandsia capillaris and Tillandsia virescens s. str. co-occur, Tillandsia virescens s. l. is restricted to altitudes above 2000 m in Argentina. Characters previously used for taxa delimitation showed continuous variation and therefore were not useful. New diagnostic characters are proposed and a key is provided for delimiting these three taxa within the complex. PMID:23805053

Capillary Structures for Exploration Life Support (Capillary Structures)

NASA Image and Video Library

2017-07-10

iss052e013146 (July 10, 2017) --- Astronaut Jack Fischer is photographed during setup of hardware for the Capillary Structures for Exploration Life Support (Capillary Structures) two sorbent demonstrations. The Capillary Structures for Exploration Life Support (Capillary Structures) investigation studies a new method using structures of specific shapes to manage fluid and gas mixtures. The investigation studies water recycling and carbon dioxide removal, benefiting future efforts to design lightweight, more reliable life support systems for future space missions.

Skin Mast Cell Promotion in Random Skin Flaps in Rats using Bone Marrow Mesenchymal Stem Cells and Amniotic Membrane

PubMed

Chehelcheraghi, Farzaneh; Abbaszadeh, Abolfazl; Tavafi, Magid

2018-03-06

Skin flap procedures are employed in plastic surgery, but failure can lead to necrosis of the flap. Studies have used bone marrow mesenchymal stem cells (BM-MSCs) to improve flap viability. BM-MSCs and acellular amniotic membrane (AAM) have been introduced as alternatives. The objective of this study was to evaluate the effect of BM-MSCs and AAM on mast cells of random skin flaps (RSF) in rats. RSFs (80 × 30 mm) were created on 40 rats that were randomly assigned to one of four groups, including (I) AAM, (II) BM-MSCs, (III) BM-MSCs/AAM, and (IV) saline (control). Transplantation was carried out during the procedure (zero day). Flap necrosis was observed on day 7, and skin samples were collected from the transition line of the flap to evaluate the total number and types of mast cells. The development and the total number of mast cells were related to the development of capillaries. The results of one-way ANOVA indicated that there was no statistically significant difference between the mean numbers of mast cell types for different study groups. However, the difference between the total number of mast cells in the study groups was statistically significant (p = 0.001). The present study suggests that the use of AAM/BM-MSCs can improve the total number of mast cells and accelerate the growth of capillaries at the transient site in RSFs in rats.

Changes in oxygenation and phosphocreatine during exercise and recovery in relation to fiber types and capillary supply in human skeletal muscle

NASA Astrophysics Data System (ADS)

Hamaoka, Takatumi; Mizuno, Masano; Osada, Takuya; Ratkevicius, Aivaras; Nielsen, Alexander N.; Nakagawa, Yoshinao; Katsumura, Toshihito; Shimomitsu, Teruichi; Quistorff, Bjorn

1998-01-01

The purpose of this study was to examine the relationship between histochemical characteristics obtained from the gastrocnemius and changes in muscle energetics. Muscle oxygenation was determined by near infrared spectroscopy, and phosphocreatine (PCr) by 31-phosphorus magnetic resonance spectroscopy (31P-MRS) during a submaximal plantar flexion exercise and recovery. The relative occurrence (%) of slow-twitch fibers (ST), fast-twitch oxidative fibers (FTa), fast-twitch glycolytic fibers (FTb), and the number of capillaries per fiber (Cap/Fiber) were also determined. The sum of %ST and %FTa (%ST + %FTa) was 85.8 +/- 8.74% (mean +/- SD), while the number of Cap/Fiber was 2.52 +/- 0.63. The initial rate of deoxygenation (Ratedeoxy) at the beginning of the exercise was 2.43 +/- 0.95 %(DOT)sec-1. The time constants (Tc) for the recovery of PCr and muscle oxygenation after exercise were 22.1 +/- 6.3 sec. and 20.3 +/- 13.6 sec., respectively. The %ST + FTa, and the number of Cap/Fiber were each positively correlated to the Ratedeoxy (P < 0.05). The %ST + %FTa, and the number of Cap/Fiber were negatively correlated to the Tc for PCr recovery (P < 0.05), but not correlated to that for muscle oxygenation recovery. In conclusion, the Ratedeoxy during localized submaximal exercise, and the Tc for PCr recovery are indicators of the muscle's oxidative capacity.

Changes in oxygenation and phosphocreatine during exercise and recovery in relation to fiber types and capillary supply in human skeletal muscle

NASA Astrophysics Data System (ADS)

Hamaoka, Takatumi; Mizuno, Masano; Osada, Takuya; Ratkevicius, Aivaras; Nielsen, Alexander N.; Nakagawa, Yoshinao; Katsumura, Toshihito; Shimomitsu, Teruichi; Quistorff, Bjorn

1997-12-01

The purpose of this study was to examine the relationship between histochemical characteristics obtained from the gastrocnemius and changes in muscle energetics. Muscle oxygenation was determined by near infrared spectroscopy, and phosphocreatine (PCr) by 31-phosphorus magnetic resonance spectroscopy (31P-MRS) during a submaximal plantar flexion exercise and recovery. The relative occurrence (%) of slow-twitch fibers (ST), fast-twitch oxidative fibers (FTa), fast-twitch glycolytic fibers (FTb), and the number of capillaries per fiber (Cap/Fiber) were also determined. The sum of %ST and %FTa (%ST + %FTa) was 85.8 +/- 8.74% (mean +/- SD), while the number of Cap/Fiber was 2.52 +/- 0.63. The initial rate of deoxygenation (Ratedeoxy) at the beginning of the exercise was 2.43 +/- 0.95 %(DOT)sec-1. The time constants (Tc) for the recovery of PCr and muscle oxygenation after exercise were 22.1 +/- 6.3 sec. and 20.3 +/- 13.6 sec., respectively. The %ST + FTa, and the number of Cap/Fiber were each positively correlated to the Ratedeoxy (P < 0.05). The %ST + %FTa, and the number of Cap/Fiber were negatively correlated to the Tc for PCr recovery (P < 0.05), but not correlated to that for muscle oxygenation recovery. In conclusion, the Ratedeoxy during localized submaximal exercise, and the Tc for PCr recovery are indicators of the muscle's oxidative capacity.

New type of capillary for use as ion beam collimator and air-vacuum interface

NASA Astrophysics Data System (ADS)

Stoytschew, V.; Schulte-Borchers, M.; Božičević Mihalića, Iva; Perez, R. D.

2016-08-01

Glass capillaries offer a unique way to combine small diameter ion beam collimation with an air-vacuum interface for ambient pressure ion beam applications. Usually they have an opening diameter of a few microns, limiting the air inflow sufficiently to maintain stable conditions on the vacuum side. As the glass capillaries generally are quite thin and fragile, handling of the capillary in the experiment becomes difficult. They also introduce an X-ray background produced by the capillary wall material, which has to be shielded or subtracted from the data for Particle Induced X-ray Emission (PIXE) applications. To overcome both drawbacks, a new type of conical glass capillary has been developed. It has a higher wall thickness eliminating the low energy X-ray background produced by common capillaries and leading to a more robust lens. The results obtained in first tests show, that this new capillary is suitable for ion beam collimation and encourage further work on the capillary production process to provide thick wall capillaries with an outlet diameter in the single digit micro- or even nanometre range.

Pore-scale modeling of Capillary Penetration of Wetting Liquid into 3D Fibrous Media: A Critical Examination of Equivalent Capillary Concept

NASA Astrophysics Data System (ADS)

Palakurthi, Nikhil Kumar; Ghia, Urmila; Comer, Ken

2013-11-01

Capillary penetration of liquid through fibrous porous media is important in many applications such as printing, drug delivery patches, sanitary wipes, and performance fabrics. Historically, capillary transport (with a distinct liquid propagating front) in porous media is modeled using capillary-bundle theory. However, it is not clear if the capillary model (Washburn equation) describes the fluid transport in porous media accurately, as it assumes uniformity of pore sizes in the porous medium. The present work investigates the limitations of the applicability of the capillary model by studying liquid penetration through virtual fibrous media with uniform and non-uniform pore-sizes. For the non-uniform-pore fibrous medium, the effective capillary radius of the fibrous medium was estimated from the pore-size distribution curve. Liquid penetration into the 3D virtual fibrous medium at micro-scale was simulated using OpenFOAM, and the numerical results were compared with the Washburn-equation capillary-model predictions. Preliminary results show that the Washburn equation over-predicts the height rise in the early stages (purely inertial and visco-inertial stages) of capillary transport.

Two-dimensional capillary electrophoresis: capillary isoelectric focusing and capillary zone electrophoresis with laser-induced fluorescence detection

PubMed Central

Dickerson, Jane A.; Ramsay, Lauren M.; Dada, Oluwatosin O.; Cermak, Nathan

2011-01-01

Capillary isoelectric focusing and capillary zone electrophoresis are coupled with laser-induced fluorescence detection to create an ultrasensitive two-dimensional separation method for proteins. In this method, two capillaries are joined through a buffer filled interface. Separate power supplies control the potential at the injection end of the first capillary and at the interface; the detector is held at ground potential. Proteins are labeled with the fluorogenic reagent Chromeo P503, which preserves the isoelectric point of the labeled protein. The labeled proteins were mixed with ampholytes and injected into the first dimension capillary. A focusing step was performed with the injection end of the capillary at high pH and the interface at low pH. To mobilize components, the interface was filled with a high pH buffer, which was compatible with the second dimension separation. A fraction was transferred to the second dimension capillary for separation. The process of fraction transfer and second dimension separation was repeated two dozen times. The separation produced a spot capacity of 125. PMID:20603830

Capillarics: pre-programmed, self-powered microfluidic circuits built from capillary elements.

PubMed

Safavieh, Roozbeh; Juncker, David

2013-11-07

Microfluidic capillary systems employ surface tension effects to manipulate liquids, and are thus self-powered and self-regulated as liquid handling is structurally and chemically encoded in microscale conduits. However, capillary systems have been limited to perform simple fluidic operations. Here, we introduce complex capillary flow circuits that encode sequential flow of multiple liquids with distinct flow rates and flow reversal. We first introduce two novel microfluidic capillary elements including (i) retention burst valves and (ii) robust low aspect ratio trigger valves. These elements are combined with flow resistors, capillary retention valves, capillary pumps, and open and closed reservoirs to build a capillary circuit that, following sample addition, autonomously delivers a defined sequence of multiple chemicals according to a preprogrammed and predetermined flow rate and time. Such a circuit was used to measure the concentration of C-reactive protein. This work illustrates that as in electronics, complex capillary circuits may be built by combining simple capillary elements. We define such circuits as "capillarics", and introduce symbolic representations. We believe that more complex circuits will become possible by expanding the library of building elements and formulating abstract design rules.

Does cranberry have a role in catheter-associated urinary tract infections?

PubMed

Thomas, Dominique; Rutman, Matthew; Cooper, Kimberly; Abrams, Andrew; Finkelstein, Julia; Chughtai, Bilal

2017-11-01

Catheter-associated urinary tract infections (CA-UTIs) are a prevalent and costly condition, with very few therapeutic options. We sought to evaluate the efficacy of an oral cranberry supplement on CA-UTIs over a six-month period. Subjects with long-term indwelling catheters and recurrent symptomatic CA-UTIs were enrolled to take a once-daily oral cranberry supplement with 36 mg of the active ingredient proanthocyanidin (PACs). Primary outcome was reducing the number of symptomatic CA-UTIs. This was defined by ≥10 3 (cfu)/mL of ≥1 bacterial species in a single catheter urine specimen and signs and symptoms compatible with CA-UTI. Secondary outcomes included bacterial counts and resistance patterns to antibiotics. Thirty-four patients were enrolled in the trial; 22 patients (mean age 77.22 years, 77.27% were men) completed the study. Cranberry was effective in reducing the number of symptomatic CA-UTIs in all patients (n=22). Resistance to antibiotics was reduced by 28%. Furthermore, colony counts were reduced by 58.65%. No subjects had adverse events while taking cranberry. The cranberry supplement reduced the number of symptomatic CA-UTIs, antibiotic resistances, and major causative organisms in this cohort. Larger, placebo-controlled studies are needed to further define the role of cranberry in CA-UTIs.

Does cranberry have a role in catheter-associated urinary tract infections?

PubMed Central

Thomas, Dominique; Rutman, Matthew; Cooper, Kimberly; Abrams, Andrew; Finkelstein, Julia; Chughtai, Bilal

2017-01-01

Introduction Catheter-associated urinary tract infections (CA-UTIs) are a prevalent and costly condition, with very few therapeutic options. We sought to evaluate the efficacy of an oral cranberry supplement on CA-UTIs over a six-month period. Methods Subjects with long-term indwelling catheters and recurrent symptomatic CA-UTIs were enrolled to take a once-daily oral cranberry supplement with 36 mg of the active ingredient proanthocyanidin (PACs). Primary outcome was reducing the number of symptomatic CA-UTIs. This was defined by ≥103 (cfu)/mL of ≥1 bacterial species in a single catheter urine specimen and signs and symptoms compatible with CA-UTI. Secondary outcomes included bacterial counts and resistance patterns to antibiotics. Results Thirty-four patients were enrolled in the trial; 22 patients (mean age 77.22 years, 77.27% were men) completed the study. Cranberry was effective in reducing the number of symptomatic CA-UTIs in all patients (n=22). Resistance to antibiotics was reduced by 28%. Furthermore, colony counts were reduced by 58.65%. No subjects had adverse events while taking cranberry. Conclusions The cranberry supplement reduced the number of symptomatic CA-UTIs, antibiotic resistances, and major causative organisms in this cohort. Larger, placebo-controlled studies are needed to further define the role of cranberry in CA-UTIs. PMID:29072566

Particle sizer and DNA sequencer

DOEpatents

Olivares, Jose A.; Stark, Peter C.

2005-09-13

An electrophoretic device separates and detects particles such as DNA fragments, proteins, and the like. The device has a capillary which is coated with a coating with a low refractive index such as Teflon.RTM. AF. A sample of particles is fluorescently labeled and injected into the capillary. The capillary is filled with an electrolyte buffer solution. An electrical field is applied across the capillary causing the particles to migrate from a first end of the capillary to a second end of the capillary. A detector light beam is then scanned along the length of the capillary to detect the location of the separated particles. The device is amenable to a high throughput system by providing additional capillaries. The device can also be used to determine the actual size of the particles and for DNA sequencing.

Modeling Wind Wave Evolution from Deep to Shallow Water

DTIC Science & Technology

2013-09-30

Janssen Theiss Research, PO Box 1533, El Granada , CA 94018 t: 415 609 5359 e: ttjanssen@gmail.com Thomas H. C. Herbers Department of Oceanography...NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Theiss Research,PO Box 1533,El Granada ,CA,94018 8

Subgrouping Chronic Fatigue Syndrome Patients by Genetic and Immune Profiling

DTIC Science & Technology

2013-10-01

CONTRACTING ORGANIZATION : Stanford University Stanford, CA 94305-2004 REPORT DATE...Rosemary Fernandez 5e. TASK NUMBER E-Mail: gilberto@stanford.edu 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES...8. PERFORMING ORGANIZATION REPORT NUMBER Stanford University Stanford, CA 94305-2004 9. SPONSORING / MONITORING AGENCY NAME

Total neuron numbers in CA1-4 sectors of the dog hippocampus.

PubMed

Rağbetli, Murat Cetin; Aydinlioğlu, Atif; Koyun, Necat; Yayici, Recep; Arslan, Kadir

2010-06-01

Early reports addressed morphological asymmetry in the cross-sectional width of the rat hippocampus. The present study was aimed at counting total number of neurons in CA1-4 sectors and the subiculum of the dog hippocampus as well as investigating possible left /right and male/female asymmetry. Adult mongrel dogs (8 female and 5 male) were assessed by the right and left pawedness and sacrificed by exsanguinations. In each hippocampus dissected, the total neuron numbers of CAs and subiculum were estimated by the physical fractioning method. Significant hemispheric asymmetries were found in the number of pyramidal cells of CA1, CA3/2, CA4 and the subiculum. Sex difference was also found in the subiculum, in favour of the males. Our study indicated a left dominant asymmetry in males and right dominancy in females as well as no functional asymmetry in specific regions of the dog hippocampus. Further investigations are necessary to verify the hypothesis that hippocampal morphological asymmetries in normal subjects are functionally related in memory or in cognitive skills.

Skeletal age and age verification in youth sport.

PubMed

Malina, Robert M

2011-11-01

Problems with accurate chronological age (CA) reporting occur on a more or less regular basis in youth sports. As a result, there is increasing discussion of age verification. Use of 'bone age' or skeletal age (SA) for the purpose of estimating or verifying CA has been used in medicolegal contexts for many years and also in youth sport competitions. This article reviews the concept of SA, and the three most commonly used methods of assessment. Variation in SA within CA groups among male soccer players and female artistic gymnasts is evaluated relative to the use of SA as a tool for verification of CA. Corresponding data for athletes in several other sports are also summarized. Among adolescent males, a significant number of athletes will be identified as older than a CA cutoff because of advanced skeletal maturation when they in fact have a valid CA. SA assessments of soccer players are comparable to MRI assessments of epiphyseal-diaphyseal union of the distal radius in under-17 soccer players. Both protocols indicate a relatively large number of false negatives among youth players aged 15-17 years. Among adolescent females, a significant number of age-eligible artistic gymnasts will be identified as younger than the CA cutoff because of later skeletal maturation when in fact they have a valid CA. There is also the possibility of false positives-identifying gymnasts as younger than the CA cutoff because of late skeletal maturation when they have a valid CA. The risk of false negatives and false positives implies that SA is not a valid indicator of CA.