An upscaling method and a numerical analysis of swelling/shrinking processes in a compacted bentonite/sand mixture

NASA Astrophysics Data System (ADS)

Xie, M.; Agus, S. S.; Schanz, T.; Kolditz, O.

2004-12-01

This paper presents an upscaling concept of swelling/shrinking processes of a compacted bentonite/sand mixture, which also applies to swelling of porous media in general. A constitutive approach for highly compacted bentonite/sand mixture is developed accordingly. The concept is based on the diffuse double layer theory and connects microstructural properties of the bentonite as well as chemical properties of the pore fluid with swelling potential. Main factors influencing the swelling potential of bentonite, i.e. variation of water content, dry density, chemical composition of pore fluid, as well as the microstructures and the amount of swelling minerals are taken into account. According to the proposed model, porosity is divided into interparticle and interlayer porosity. Swelling is the potential of interlayer porosity increase, which reveals itself as volume change in the case of free expansion, or turns to be swelling pressure in the case of constrained swelling. The constitutive equations for swelling/shrinking are implemented in the software GeoSys/RockFlow as a new chemo-hydro-mechanical model, which is able to simulate isothermal multiphase flow in bentonite. Details of the mathematical and numerical multiphase flow formulations, as well as the code implementation are described. The proposed model is verified using experimental data of tests on a highly compacted bentonite/sand mixture. Comparison of the 1D modelling results with the experimental data evidences the capability of the proposed model to satisfactorily predict free swelling of the material under investigation. Copyright

Tissue fluid pressures - From basic research tools to clinical applications

NASA Technical Reports Server (NTRS)

Hargens, Alan R.; Akeson, Wayne H.; Mubarak, Scott J.; Owen, Charles A.; Gershuni, David H.

1989-01-01

This paper describes clinical applications of two basic research tools developed and refined in the past 20 years: the wick catheter (for measuring tissue fluid pressure) and the colloid osmometer (for measuring osmotic pressure). Applications of the osmometer include estimations of the reduced osmotic pressure of sickle-cell hemoglobin with deoxygenation, and of reduced swelling pressure of human nucleus pulposus with hydration or upon action of certain enzymes. Clinical uses of the wick-catheter technique include an improvement of diagnosis and treatment of acute and chronic compartment syndromes, the elucidation of the tissue pressure thresholds for neuromuscular dysfunction, and the development of a better tourniquet for orthopedics.

Flakeboard thickness swelling. Part II, Fundamental response of board properties to steam injection pressing

Treesearch

Robert L. Geimer; Jin Heon Kwon

1999-01-01

The results of this study showed that the same relative reductions in thickness swelling (TS) previously obtained with steam-injection-pressed (SIP) resinless mats are also obtained in boards bonded with 3% isocyanate resin. Reductions in thickness swelling were proportional to steam time and pressure. Thickness swelling of 40% measured in conventionally pressed boards...

Rheological behavior of rat mesangial cells during swelling in vitro.

PubMed

Craelius, W; Huang, C J; Guber, H; Palant, C E

1997-01-01

The response of cells to mechanical forces depends on the rheological properties of their membranes and cytoplasm. To characterize those properties, mechanical and electrical responses to swelling were measured in rat mesangial cells (MC) using electrophysiologic and video microscopic techniques. Ion transport rates during hyposmotic exposures were measured with whole-cell recording electrodes. Results showed that cell swelling varied nonlinearly with positive internal pressure, consistent with a viscoelastic cytoplasm. The extrapolated area expansivity modulus for small deformations was estimated to be 450 dyne/cm. Cell swelling, caused either by positive pipet pressure or hyposmotic exposure (40-60 mOsm Kg-1), rapidly induced an outwardly rectifying membrane conductance with an outward magnitude 4-5 times the baseline conductance of 0.9 +/- 0.5 nS (p < .01). Swelling-induced (SI) current was weakly selective for K+ over Na+, partially reversed upon return to isotonicity, and was antagonized by 0.5 mM GdCl3 (p < 0.02; n = 6). Isolated cells treated with GdCl3 rapidly lysed after hypotonic exposure, in contrast to untreated cells that exhibited regulatory volume decrease (RVD). Our results indicate that volume regulation by MC depends upon a large swelling-induced K+ efflux, and suggest that swelling in MC is a viscoelastic process, with a viscosity dependent on the degree of swelling.

High-Pressure CO2 Sorption in Polymers of Intrinsic Microporosity under Ultrathin Film Confinement.

PubMed

Ogieglo, Wojciech; Ghanem, Bader; Ma, Xiaohua; Wessling, Matthias; Pinnau, Ingo

2018-04-04

Ultrathin microporous polymer films are pertinent to the development and further spread of nanotechnology with very promising potential applications in molecular separations, sensors, catalysis, or batteries. Here, we report high-pressure CO 2 sorption in ultrathin films of several chemically different polymers of intrinsic microporosity (PIMs), including the prototypical PIM-1. Films with thicknesses down to 7 nm were studied using interference-enhanced in situ spectroscopic ellipsometry. It was found that all PIMs swell much more than non-microporous polystyrene and other high-performance glassy polymers reported previously. Furthermore, chemical modifications of the parent PIM-1 strongly affected the swelling magnitude. By investigating the behavior of relative refractive index, n rel , it was possible to study the interplay between micropores filling and matrix expansion. Remarkably, all studied PIMs showed a maximum in n rel at swelling of 2-2.5% indicating a threshold point above which the dissolution in the dense matrix started to dominate over sorption in the micropores. At pressures above 25 bar, all PIMs significantly plasticized in compressed CO 2 and for the ones with the highest affinity to the penetrant, a liquidlike mixing typical for rubbery polymers was observed. Reduction of film thickness below 100 nm revealed pronounced nanoconfinement effects and resulted in a large swelling enhancement and a quick loss of the ultrarigid character. On the basis of the partial molar volumes of the dissolved CO 2 , the effective reduction of the T g was estimated to be ∼200 °C going from 128 to 7 nm films.

Spinal Cord Swelling and Alterations in Hydrostatic Pressure After Acute Injury

DTIC Science & Technology

2016-10-01

8217 started’ surgeries ’ as’ part’ of’ Aim’ 2’ to’ determine...and!to!guide!optimal!perfusion!support! based !on!that.!The! PRx! has! not! been! investigated! in! SCI,! but! given! that! the! cord! also! swells! and...2.!Animal!training!/! Surgery ! ! ! ! ! ! ! ! ! ! ! ! ! 3.!Spinal!cord!monitoring!of!pressure,! oxygenation,!SCBF!and! microdiaysis

Baker cyst

MedlinePlus

Popliteal cyst; Bulge-knee ... Baker cyst is caused by swelling in the knee. The swelling is due to an increase in the fluid that lubricates the knee joint (synovial fluid). When pressure builds up, fluid ...

Apparatus measures swelling of membranes in electrochemical cells

NASA Technical Reports Server (NTRS)

Hennigan, T. J.

1965-01-01

Apparatus consisting of a pressure plate unit, four springs of known spring constant and a micrometer measures the swelling and force exerted by the polymer membranes of alkaline electrochemical cells.

A Process to Reduce DC Ingot Butt Curl and Swell

NASA Astrophysics Data System (ADS)

Yu, Ho

1980-11-01

A simple and effective process to reduce DC ingot butt curl and swell has been developed in the Ingot Casting Division of Alcoa Technical Center.1 In the process, carbon dioxide gas is dissolved under high pressure into the ingot cooling water upstream of the mold during the first several inches of the ingot cast. As the cooling water exits from the mold, the dissolved gas evolves as micron-size bubbles, forming a temporary effective insulation layer on the ingot surface. This reduces thermal stress in the ingot butt. An insulation pad covering about 60% of the bottom block is used in conjunction with the carbon dioxide injection when maximum butt swell reduction is desired. The process, implemented in four Alcoa ingot plants, has proven extremely successful.

In situ microscopy reveals reversible cell wall swelling in kelp sieve tubes: one mechanism for turgor generation and flow control?

PubMed

Knoblauch, Jan; Tepler Drobnitch, Sarah; Peters, Winfried S; Knoblauch, Michael

2016-08-01

Kelps, brown algae (Phaeophyceae) of the order Laminariales, possess sieve tubes for the symplasmic long-distance transport of photoassimilates that are evolutionarily unrelated but structurally similar to the tubes in the phloem of vascular plants. We visualized sieve tube structure and wound responses in fully functional, intact Bull Kelp (Nereocystis luetkeana [K. Mertens] Postels & Ruprecht 1840). In injured tubes, apparent slime plugs formed but were unlikely to cause sieve tube occlusion as they assembled at the downstream side of sieve plates. Cell walls expanded massively in the radial direction, reducing the volume of the wounded sieve elements by up to 90%. Ultrastructural examination showed that a layer of the immediate cell wall characterized by circumferential cellulose fibrils was responsible for swelling and suggested that alginates, abundant gelatinous polymers of the cell wall matrix, were involved. Wall swelling was rapid, reversible and depended on intracellular pressure, as demonstrated by pressure-injection of silicon oil. Our results revive the concept of turgor generation and buffering by swelling cell walls, which had fallen into oblivion over the last century. Because sieve tube transport is pressure-driven and controlled physically by tube diameter, a regulatory role of wall swelling in photoassimilate distribution is implied in kelps. © 2016 John Wiley & Sons Ltd.

Modelling of wicking and moisture interactions of flax and viscose fibres.

PubMed

Stuart, T; McCall, R D; Sharma, H S S; Lyons, G

2015-06-05

Methods for assessing the wicking properties of individual fibre bundles have been developed from models based on the original Washburn equation (WE) and the modified Washburn equation (MWE), which also accounts for swelling. Both models gave indication of differences in wicking properties of flax and the viscose fibres, though MWE gave additional information that could be interpreted in terms of the physical model. Wicking of the viscose fibres is mainly via inter-fibre capillaries while that of flax is a combination of inter-fibre capillaries and lumen present in some elementary fibres. The degree of swelling and associated rotation of flax fibre in a vapour pressure range of 1-6torr were monitored using an environmental scanning electron microscope (ESEM). Viscose fibre exhibited swelling under the same conditions but did not rotate. The two techniques highlighted different mechanisms of wicking which can be used for monitoring moisture uptake/swelling of treated fibres for fabrication of composites. Copyright © 2015 Elsevier Ltd. All rights reserved.

Inverse Association between Air Pressure and Rheumatoid Arthritis Synovitis

PubMed Central

Furu, Moritoshi; Nakabo, Shuichiro; Ohmura, Koichiro; Nakashima, Ran; Imura, Yoshitaka; Yukawa, Naoichiro; Yoshifuji, Hajime; Matsuda, Fumihiko; Ito, Hiromu; Fujii, Takao; Mimori, Tsuneyo

2014-01-01

Rheumatoid arthritis (RA) is a bone destructive autoimmune disease. Many patients with RA recognize fluctuations of their joint synovitis according to changes of air pressure, but the correlations between them have never been addressed in large-scale association studies. To address this point we recruited large-scale assessments of RA activity in a Japanese population, and performed an association analysis. Here, a total of 23,064 assessments of RA activity from 2,131 patients were obtained from the KURAMA (Kyoto University Rheumatoid Arthritis Management Alliance) database. Detailed correlations between air pressure and joint swelling or tenderness were analyzed separately for each of the 326 patients with more than 20 assessments to regulate intra-patient correlations. Association studies were also performed for seven consecutive days to identify the strongest correlations. Standardized multiple linear regression analysis was performed to evaluate independent influences from other meteorological factors. As a result, components of composite measures for RA disease activity revealed suggestive negative associations with air pressure. The 326 patients displayed significant negative mean correlations between air pressure and swellings or the sum of swellings and tenderness (p = 0.00068 and 0.00011, respectively). Among the seven consecutive days, the most significant mean negative correlations were observed for air pressure three days before evaluations of RA synovitis (p = 1.7×10−7, 0.00027, and 8.3×10−8, for swellings, tenderness and the sum of them, respectively). Standardized multiple linear regression analysis revealed these associations were independent from humidity and temperature. Our findings suggest that air pressure is inversely associated with synovitis in patients with RA. PMID:24454853

Analysis of Effective Interconnectivity of DegraPol-foams Designed for Negative Pressure Wound Therapy

PubMed Central

Milleret, Vincent; Bittermann, Anne Greet; Mayer, Dieter; Hall, Heike

2009-01-01

Many wounds heal slowly and are difficult to manage. Therefore Negative Pressure Wound Therapy (NPWT) was developed where polymer foams are applied and a defined negative pressure removes wound fluid, reduces bacterial burden and increases the formation of granulation tissue. Although NPWT is used successfully, its mechanisms are not well understood. In particular, different NPWT dressings were never compared. Here a poly-ester urethane Degrapol® (DP)-foam was produced and compared with commercially available dressings (polyurethane-based and polyvinyl-alcohol-based) in terms of apparent pore sizes, swelling and effective interconnectivity of foam pores. DP-foams contain relatively small interconnected pores; PU-foams showed large pore size and interconnectivity; whereas PVA-foams displayed heterogeneous and poorly interconnected pores. PVA-foams swelled by 40 %, whereas DP- and PU-foams remained almost without swelling. Effective interconnectivity was investigated by submitting fluorescent beads of 3, 20 and 45 μm diameter through the foams. DP- and PU-foams removed 70-90 % of all beads within 4 h, independent of the bead diameter or bead pre-adsorption with serum albumin. For PVA-foams albumin pre-adsorbed beads circulated longer, where 20 % of 3 μm and 10 % of 20 μm diameter beads circulated after 96 h. The studies indicate that efficient bead perfusion does not only depend on pore size and swelling capacity, but effective interconnectivity might also depend on chemical composition of the foam itself. In addition due to the efficient sieve-effect of the foams uptake of wound components in vivo might occur only for short time suggesting other mechanisms being decisive for success of NPWT.

Effects of Cold and Compression on Edema.

ERIC Educational Resources Information Center

Sloan, J. P.; And Others

1988-01-01

Investigation of ways to treat artificially induced acute inflammatory reactions in human tissue found that neither cooling or pressure alone reduced the swelling, while a combination of the two methods produced a significant reduction in swelling. (Author/CB)

The effect of colloid osmotic pressure in human spermatozoa exposed to hypoosmotic conditions.

PubMed

Correa-Pérez, J R; Fernández-Pelegrina, R; Zarmakoupis-Zavos, P N; Zavos, P M

2003-04-01

The use of a protein source such as serum and albumin had been extensively employed as supplements of culture media for handling and culture of gametes and embryos. Protein molecules behave as colloids in solution and contribute to the osmotic pressure of fluids. The interaction of proteins in solution and spermatozoa needs to be assessed in order to determine their possible role in osmoregulation. The aim of this study was to assess possible osmoregulatory mechanisms of protein supplementation against exposure to hypoosmotic conditions by assessing the sperm's response to those environments. A stock hypoosmotic solution (HOS) was prepared by using a mixture of fructose and sodium citrate and adjusted to an osmotic pressure of 150 mOsm l-1. Another stock solution was prepared by diluting a preparation of synthetic serum supplement [SSS; 6% (v/v) total protein] with distilled water to obtain an osmotic pressure of 150 mOsm l-1 (hypoosmotic SSS or H-SSS). Three additional solutions were prepared by mixing the stock HOS and H-SSS solutions in the following proportions (v/v): (i) 75% H-SSS/25% HOS, (ii) 50% H-SSS/50% HOS and (iii) 25% H-SSS/75% HOS. Aliquots of washed spermatozoa from 18 men were diluted 1 : 10 (v/v) with each of the testing solutions and incubated for 60 min. Specimens were assessed on wet mounts for total and specific swelling patterns. Swelling patterns were classified as maximal (>50% tail length swollen) and minimal (<50% tail length swollen) swelling with or without associated sperm motility. The major finding of this study was that increasing the concentration of protein supplementation resulted in a decrease in the proportion of maximal sperm tail swelling patterns and an increase in the proportion of minimal tail swelling patterns. A proportion of spermatozoa which exhibited minimal swelling patterns were still motile in all solutions tested, and the percentage of those spermatozoa increased as the protein supplementation was also increased in the testing solutions. Incorporation of protein supplementation as described in this study delays the effect of sperm swelling in hypoosmotic conditions.

The Role of Cell Volume in the Dynamics of Seizure, Spreading Depression, and Anoxic Depolarization

PubMed Central

Ullah, Ghanim; Wei, Yina; Dahlem, Markus A; Wechselberger, Martin; Schiff, Steven J

2015-01-01

Cell volume changes are ubiquitous in normal and pathological activity of the brain. Nevertheless, we know little of how cell volume affects neuronal dynamics. We here performed the first detailed study of the effects of cell volume on neuronal dynamics. By incorporating cell swelling together with dynamic ion concentrations and oxygen supply into Hodgkin-Huxley type spiking dynamics, we demonstrate the spontaneous transition between epileptic seizure and spreading depression states as the cell swells and contracts in response to changes in osmotic pressure. Our use of volume as an order parameter further revealed a dynamical definition for the experimentally described physiological ceiling that separates seizure from spreading depression, as well as predicted a second ceiling that demarcates spreading depression from anoxic depolarization. Our model highlights the neuroprotective role of glial K buffering against seizures and spreading depression, and provides novel insights into anoxic depolarization and the relevant cell swelling during ischemia. We argue that the dynamics of seizures, spreading depression, and anoxic depolarization lie along a continuum of the repertoire of the neuron membrane that can be understood only when the dynamic ion concentrations, oxygen homeostasis,and cell swelling in response to osmotic pressure are taken into consideration. Our results demonstrate the feasibility of a unified framework for a wide range of neuronal behaviors that may be of substantial importance in the understanding of and potentially developing universal intervention strategies for these pathological states. PMID:26273829

Persistent Asymmetric Optic Disc Swelling After Long-Duration Space Flight: Implications for Pathogenesis.

PubMed

Mader, Thomas H; Gibson, C Robert; Otto, Christian A; Sargsyan, Ashot E; Miller, Neil R; Subramanian, Prem S; Hart, Stephen F; Lipsky, William; Patel, Nimesh B; Lee, Andrew G

2017-06-01

Several ophthalmic findings including optic disc swelling, globe flattening and choroidal folds have been observed in astronauts following long-duration space flight. The authors now report asymmetric choroidal expansion, disc swelling and optic disc morphologic changes in a 45-year-old astronaut which occurred during long-duration space flight and persisted following his space mission. Case study of ocular findings in an astronaut documented during and after a long-duration space flight of approximately 6 months. Before, during and after his spaceflight, he underwent complete eye examination, including fundus photography, ultrasound, and optical coherence tomography. We documented asymmetric choroidal expansion inflight that largely resolved by 30 days postflight, asymmetric disc swelling observed inflight that persisted for over 180 days postflight, asymmetric optic disc morphologic changes documented inflight by OCT that persisted for 630 days postflight and asymmetric globe flattening that began inflight and continued 660 days postflight. Lumbar puncture opening pressures obtained at 7 and 365 days post-mission were 22 and 16 cm H20 respectively. The persistent asymmetric findings noted above, coupled with the lumbar puncture opening pressures, suggest that prolonged microgravity exposure may have produced asymmetric pressure changes within the perioptic subarachnoid space.

Development, Fabrication, and Characterization of Hydrogel Based Piezoresistive Pressure Sensors with Perforated Diaphragms

PubMed Central

Orthner, M.P.; Buetefisch, Sebastian; Magda, J.; Rieth, L.W.; Solzbacher, F.

2010-01-01

Hydrogels have been demonstrated to swell in response to a number of external stimuli including pH, CO2, glucose, and ionic strength making them useful for detection of metabolic analytes. To measure hydrogel swelling pressure, we have fabricated and tested novel perforated diaphragm piezoresistive pressure sensor arrays that couple the pressure sensing diaphragm with a perforated semi-permeable membrane. The 2×2 arrays measure approximately 3 × 5 mm2 and consist of four square sensing diaphragms with widths of 1.0, 1.25, and 1.5 mm used to measure full scale pressures of 50, 25, and 5 kPa, respectively. An optimized geometry of micro pores was etched in silicon diaphragm to allow analyte diffusion into the sensor cavity where the hydrogel material is located. The 14-step front side wafer process was carried out by a commercial foundry service (MSF, Frankfurt (Oder), Germany) and diaphragm pores were created using combination of potassium hydroxide (KOH) etching and deep reactive ion etching (DRIE). Sensor characterization was performed (without the use of hydrogels) using a custom bulge testing apparatus that simultaneously measured deflection, pressure, and electrical output. Test results are used to quantify the sensor sensitivity and demonstrate proof-of-concept. Simulations showed that the sensitivity was slightly improved for the perforated diaphragm designs while empirical electrical characterization showed that the perforated diaphragm sensors were slightly less sensitive than solid diaphragm sensors. This discrepancy is believed to be due to the influence of compressive stress found within passivation layers and poor etching uniformity. The new perforated diaphragm sensors were fully functional with sensitivities ranging from 23 to 252 μV/V-kPa (FSO= 5 to 80mV), and show a higher nonlinearity at elevated pressures than identical sensors with solid diaphragms. Sensors (1.5×1.5 mm2) with perforated diaphragms (pores=40 μm) have a nonlinearity of approximately 10% while for the identical solid diaphragm sensor it was roughly 3 % over the entire 200 kPa range. This is the first time piezoresistive pressure sensors with integrated diffusion pores for detection of hydrogel swelling pressure have been fabricated and tested. PMID:20657810

Conceptual design of an astronaut hand anthropometry device

NASA Technical Reports Server (NTRS)

Mcmahan, Robert

1993-01-01

In a microgravity environment, fluid equalizes throughout the body, causing the upper body to swell. This causes the hands to swell which can cause problems for astronauts trying to do work in pressurized EVA (extravehicular activity) gloves. To better design these gloves, accurate measurements of the astronauts swollen hands are needed. Five concepts were developed in this report from an original field of 972 possible concepts. These five concepts were based on mold impression, ultrasound, laser topography, white light photography, and video imaging. From a decision matrix based on nine weighted criteria, the video imaging technique was found to be the best design to pursue.

Sustainable stabilization of sulfate-bearing soils with expansive soil-rubber technology.

DOT National Transportation Integrated Search

2013-03-01

The beneficial use of scrap tire rubber mixed with expansive soils is of interest to civil engineering : applications since the swell percent and the swell pressure can be potentially reduced with no deleterious : effect to the shear strength of the ...

Irradiation creep due to SIPA under cascade damage conditions

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

Woo, C.H.; Garner, F.A.; Holt, R.A.

1992-12-31

This paper derives the relationships between void swelling and irradiation creep due to Stress-Induced Preferred Absorption (SIPA) and SIPA-Induced Growth (SIG) under cascade damage conditions in an irradiated pressurized tube. It is found that at low swelling rates irradiation creep is a major contribution to the total diametral strain rate of the tube, whereas at high swelling rates the creep becomes a minor contribution. The anisotropy of the corresponding dislocation structure is also predicted to decline as the swelling rate increases. The theoretical predictions are found to agree very well with experimental results.

Extreme embrittlement of austenitic stainless steel irradiated to 75-81 dpa at 335-360{degrees}C

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

Porollo, S.I.; Vorobjev, A.N.; Konobeev, Yu.V.

1997-04-01

It is generally accepted that void swelling of austenitic steels ceases below some temperature in the range 340-360{degrees}C, and exhibits relatively low swelling rates up to {approximately}400{degrees}C. This perception may not be correct at all irradiation conditions, however, since it was largely developed from data obtained at relatively high displacement rates in fast reactors whose inlet temperatures were in the range 360-370{degrees}C. There is an expectation, however, that the swelling regime can shift to lower temperatures at low displacement rates via the well-known {open_quotes}temperature shift{close_quotes} phenomenon. It is also known that the swelling rates at the lower end of themore » swelling regime increase continuously at a sluggish rate, never approaching the terminal 1%/dpa level within the duration of previous experiments. This paper presents the results of an experiment conducted in the BN-350 fast reactor in Kazakhstan that involved the irradiation of argon-pressurized thin-walled tubes (0-200 MPa hoop stress) constructed from Fe-16Cr-15Ni-3Mo-Nb stabilized steel in contact with the sodium coolant, which enters the reactor at {approx}270{degrees}C. Tubes in the annealed condition reached 75 dpa at 335{degrees}C, and another set in the 20% cold-worked condition reached 81 dpa at 360{degrees}C. Upon disassembly all tubes, except those in the stress-free condition, were found to have failed in an extremely brittle fashion. The stress-free tubes exhibited diameter changes that imply swelling levels ranging from 9 to 16%. It is expected that stress-enhancement of swelling induced even larger swelling levels in the stressed tubes.« less

Counterion-induced swelling of ionic microgels

NASA Astrophysics Data System (ADS)

Denton, Alan R.; Tang, Qiyun

2016-10-01

Ionic microgel particles, when dispersed in a solvent, swell to equilibrium sizes that are governed by a balance between electrostatic and elastic forces. Tuning of particle size by varying external stimuli, such as pH, salt concentration, and temperature, has relevance for drug delivery, microfluidics, and filtration. To model swelling of ionic microgels, we derive a statistical mechanical theorem, which proves exact within the cell model, for the electrostatic contribution to the osmotic pressure inside a permeable colloidal macroion. Applying the theorem, we demonstrate how the distribution of counterions within an ionic microgel determines the internal osmotic pressure. By combining the electrostatic pressure, which we compute via both Poisson-Boltzmann theory and molecular dynamics simulation, with the elastic pressure, modeled via the Flory-Rehner theory of swollen polymer networks, we show how deswelling of ionic microgels with increasing concentration of particles can result from a redistribution of counterions that reduces electrostatic pressure. A linearized approximation for the electrostatic pressure, which proves remarkably accurate, provides physical insight and greatly eases numerical calculations for practical applications. Comparing with experiments, we explain why soft particles in deionized suspensions deswell upon increasing concentration and why this effect may be suppressed at higher ionic strength. The failure of the uniform ideal-gas approximation to adequately account for counterion-induced deswelling below close packing of microgels is attributed to neglect of spatial variation of the counterion density profile and the electrostatic pressure of incompletely neutralized macroions.

Differential Response of Neural Cells to Trauma-Induced Swelling In Vitro.

PubMed

Jayakumar, A R; Taherian, M; Panickar, K S; Shamaladevi, N; Rodriguez, M E; Price, B G; Norenberg, M D

2018-02-01

Brain edema and the associated increase in intracranial pressure are major consequences of traumatic brain injury (TBI) that accounts for most early deaths after TBI. We recently showed that acute severe trauma to cultured astrocytes results in cell swelling. We further examined whether trauma induces cell swelling in neurons and microglia. We found that severe trauma also caused cell swelling in cultured neurons, whereas no swelling was observed in microglia. While severe trauma caused cell swelling in both astrocytes and neurons, mild trauma to astrocytes, neurons, and microglia failed to cell swelling. Since extracellular levels of glutamate are increased in brain post-TBI and microglia are known to release cytokine, and direct exposure of astrocytes to these molecules are known to stimulate cell swelling, we examined whether glutamate or cytokines have any additive effect on trauma-induced cell swelling. Exposure of cultured astrocytes to trauma caused cell swelling, and such swelling was potentiated by the exposure of traumatized astrocytes to glutamate and cytokines. Conditioned medium (CM) from traumatized astrocytes had no effect on neuronal swelling post-trauma, while CM from traumatized neurons and microglia potentiated the effect of trauma on astrocyte swelling. Further, trauma significantly increased the Na-K-Cl co-transporter (NKCC) activity in neurons, and that inhibition of NKCC activity diminished the trauma-induced neuronal swelling. Our results indicate that a differential sensitivity to trauma-induced cell swelling exists in neural cells and that neurons and microglia are likely to be involved in the potentiation of the astrocyte swelling post-trauma.

Brain swelling and death in children with cerebral malaria.

PubMed

Seydel, Karl B; Kampondeni, Samuel D; Valim, Clarissa; Potchen, Michael J; Milner, Danny A; Muwalo, Francis W; Birbeck, Gretchen L; Bradley, William G; Fox, Lindsay L; Glover, Simon J; Hammond, Colleen A; Heyderman, Robert S; Chilingulo, Cowles A; Molyneux, Malcolm E; Taylor, Terrie E

2015-03-19

Case fatality rates among African children with cerebral malaria remain in the range of 15 to 25%. The key pathogenetic processes and causes of death are unknown, but a combination of clinical observations and pathological findings suggests that increased brain volume leading to raised intracranial pressure may play a role. Magnetic resonance imaging (MRI) became available in Malawi in 2009, and we used it to investigate the role of brain swelling in the pathogenesis of fatal cerebral malaria in African children. We enrolled children who met a stringent definition of cerebral malaria (one that included the presence of retinopathy), characterized them in detail clinically, and obtained MRI scans on admission and daily thereafter while coma persisted. Of 348 children admitted with cerebral malaria (as defined by the World Health Organization), 168 met the inclusion criteria, underwent all investigations, and were included in the analysis. A total of 25 children (15%) died, 21 of whom (84%) had evidence of severe brain swelling on MRI at admission. In contrast, evidence of severe brain swelling was seen on MRI in 39 of 143 survivors (27%). Serial MRI scans showed evidence of decreasing brain volume in the survivors who had had brain swelling initially. Increased brain volume was seen in children who died from cerebral malaria but was uncommon in those who did not die from the disease, a finding that suggests that raised intracranial pressure may contribute to a fatal outcome. The natural history indicates that increased intracranial pressure is transient in survivors. (Funded by the National Institutes of Health and Wellcome Trust U.K.).

Numerical studies of temperature effect on the extrusion fracture and swell of plastic micro-pipe

NASA Astrophysics Data System (ADS)

Ren, Zhong; Huang, Xingyuan; Xiong, Zhihua

2018-03-01

Temperature is a key factor that impacts extrusion forming quality of plastic micro-pipe. In this study, the effect of temperature on extrusion fracture and swell of plastic micro-pipe was investigated by numerical method. Under a certain of the melt’s flow volume, the extrusion pattern, extrusion swelling ratio of melt are obtained under different temperatures. Results show that the extrusion swelling ratio of plastic micro-pipe decreases with increasing of temperature. In order to study the reason of temperature effect, the physical distributions of plastic micro-pipe are gotten. Numerical results show that the viscosity, pressure, stress value of melt are all decreased with the increasing of temperature, which leads to decrease the extrusion swell and fracture phenomenon for the plastic micro-pipe.

Exercise-induced bilateral rectus sheath hematomas presenting as acute abdominal pain with scrotal swelling and pressure: case report and review.

PubMed

Auten, Jonathan D; Schofer, Joel M; Banks, Steven L; Rooney, Timothy B

2010-04-01

Rectus sheath hematoma (RSH) is an uncommon but significant cause of acute abdominal pain in patients presenting to the Emergency Department. RSHs are often misdiagnosed as other more common causes of abdominal pain. This case describes a 23-year-old male presenting with acute abdominal pain, scrotal swelling, and associated scrotal pressure. The case highlights the uniqueness of this particular presentation and the clinical features, risk factors, diagnosis, and treatment of RSH. Published by Elsevier Inc.

What Causes Ankle Swelling During Pregnancy - And What Can I do About it?

MedlinePlus

... or walk in the pool. Although there's little research on the use of water pressure for foot and ankle swelling, standing or walking in a pool seems to help compress tissues in the legs and might provide ... Some research suggests that foot massage and reflexology, which involves ...

Bilateral parotitis in a patient under continuous positive airway pressure treatment.

PubMed

Abdullayev, Ruslan; Saral, Filiz Cosku; Kucukebe, Omer Burak; Sayiner, Hakan Sezgin; Bayraktar, Cem; Akgun, Sadik

Many conditions such as bacterial and viral infectious diseases, mechanical obstruction due to air and calculi and drugs can cause parotitis. We present a case of unusual bilateral parotitis in a patient under non-invasive continuous positive airway pressure (CPAP) therapy for chronic obstructive pulmonary disease exacerbation in intensive care unit. A 36-year-old patient was admitted to intensive care unit with the diagnosis of chronic obstructive pulmonary disease exacerbation. Antibiotherapy, bronchodilator therapy and non-invasive positive pressure ventilation were applied as treatment regimen. Painless swellings developed on the 3rd day of admission on the right and a day after this on the left parotid glands. Amylase levels were increased and ultrasonographic evaluation revealed bilateral parotitis. No intervention was made and the therapy was continued. The patient was discharged on the 6th day with clinical improvement and regression of parotid swellings without any complications. Parotitis may have occurred after retrograde air flow in the Stensen duct during CPAP application. After the exclusion of possible viral and bacteriological etiologies and possible drug reactions we can focus on this diagnosis. Copyright © 2014 Sociedade Brasileira de Anestesiologia. Published by Elsevier Editora Ltda. All rights reserved.

Development of swelling/floating gastroretentive drug delivery system based on a combination of hydroxyethyl cellulose and sodium carboxymethyl cellulose for Losartan and its clinical relevance in healthy volunteers with CYP2C9 polymorphism.

PubMed

Chen, Ray-Neng; Ho, Hsiu-O; Yu, Chiao-Ya; Sheu, Ming-Thau

2010-01-31

The aim of this study was to develop an optimal gastroretentive drug delivery system (GRDDS) for administering Losartan. Additionally, the influence of optimized GRDDS on the bioavailability of Losartan and the formation extent of active metabolite E3174 by CYP2C9 polymorphism was investigated. Swellable and floatable GRDDS tablets combining hydroxyethyl cellulose (HEC), sodium carboxymethyl cellulose (NaCMC), and sodium bicarbonate were prepared at various compression pressures for evaluating swelling characteristics and floating capacity. Then Losartan was incorporated into optimized formulations for in vitro and in vivo characterizations. An appropriate ratio of HEC to NaCMC, addition of sodium bicarbonate, and compression at lower pressures resulted in the tablets floating over SGF for more than 16 h and swelling to 2 cm in diameter within 3h. The release patterns of Losartan from these tablets were pH-dependent. Results of the clinical trials showed that the mean bioavailability from GRD-A (HEC 91.67%, sodium bicarbonate 3.33% and Losartan 8.33%) was approximately 164%, relative to the immediate-release product (Cozaar). MRT and t(max) values were greater and C(max) values were lower for the GRDDS tablets compared with Cozaa. The lower bioavailability of Losartan in the CYP2C9*1/*1 subjects than CYP2C9*1/*3 subjects was found and could be due to the variety of enzymatic activity. Copyright 2009 Elsevier B.V. All rights reserved.

Permeability Evolution of Propped Artificial Fractures in Green River Shale

NASA Astrophysics Data System (ADS)

Li, Xiang; Feng, Zijun; Han, Gang; Elsworth, Derek; Marone, Chris; Saffer, Demian; Cheon, Dae-Sung

2017-06-01

This paper compares the evolution of permeability with effective stress in propped fractures in shale for native CH4 compared with that for sorbing CO2, slightly sorbing N2 and non-sorbing He. We examine the response for laboratory experiments on artificial propped fractures in Green River Shale to explore mechanisms of proppant embedment and fracture diagenesis. Split cylindrical specimens sandwich a proppant bead-pack at a constant confining stress of 20 MPa and with varied pore pressure. Permeability and sorption characteristics are measured with the pulse transient method. To explore the effect of swelling and embedment on fracture surface geometry, we measure the evolution of conductivity characteristics for different proppant geometries (single layer vs. multilayer), gas saturation and specimen variation in order to simulate both production and enhanced gas recovery. The resulting morphology of embedment is measured by white light interferometry and characterized via surface roughness parameter of mean, maximum and root-mean-square amplitudes. For both strongly (CO2, CH4) and slightly adsorptive gases (N2), the permeability first decreases with an increase in gas pressure due to swelling before effective stress effects dominate above the Langmuir pressure threshold. CO2 with its highest adsorption affinity produces the lowest permeability among these three gas permeants. Monolayer propped specimens show maximum swelling and lowered k/k 0 ratio and increased embedment recorded in the surface roughness relative to the multilayered specimens. Permeabilities measured for both injection and depletion cycles generally overlap and are repeatable with little hysteresis. This suggests the dominant role of reversible swelling over irreversible embedment. Gas permeant composition and related swelling have an important effect on the permeability evolution of shales.

FURTHER STUDIES ON THE KINETICS OF OSMOSIS IN LIVING CELLS

PubMed Central

Lucké, Balduin; Hartline, H. Keffer; McCutcheon, Morton

1931-01-01

Using unfertilized eggs of Arbacia punctulata as natural osmometers an attempt has been made to account for the course of swelling and shrinking of these cells in anisotonic solutions by means of the laws governing osmosis and diffusion. The method employed has been to compute permeability of the cell to water, as measured by the rate of volume change per unit of cell surface per unit of osmotic pressure outstanding between the cell and its medium. Permeability to water as here defined and as somewhat differently defined by Northrop is approximately constant during swelling and shrinking, at least for the first several minutes of these processes. Permeability is found to be independent of the osmotic pressure of the solution in which cells are swelling. Water is found to leave cells more readily than it enters, that is, permeability is greater during exosmosis than during endosmosis. PMID:19872594

Downregulation of Glutamine Synthetase via GLAST Suppression Induces Retinal Axonal Swelling in a Rat Ex Vivo Hydrostatic Pressure Model

PubMed Central

Yoshitomi, Takeshi; Zorumski, Charles F.; Izumi, Yukitoshi

2011-01-01

Purpose. High levels of glutamate can be toxic to retinal GCs. Thus, effective buffering of extracellular glutamate is important in preserving retinal structure and function. GLAST, a major glutamate transporter in the retina, and glutamine synthetase (GS) regulate extracellular glutamate accumulation and prevent excitotoxicity. This study was an examination of changes in function and expression of GLAST and GS in ex vivo rat retinas exposed to acute increases in ambient pressure. Methods. Ex vivo rat retinas were exposed to elevated hydrostatic pressure for 24 hours. The expression of GLAST and GS were examined using immunochemistry and real-time PCR analysis. Also examined were the effects of (2S,3S)-3-[3-[4-(trifluoromethyl) benzoylamino] benzyloxy] aspartate (TFB-TBOA), an inhibitor of glutamate transporters, and l-methionine-S-sulfoximine (MSO), an inhibitor of GS. Results. In this acute model, Western blot and real-time RT-PCR analyses revealed that substantially (75 mm Hg), but not moderately (35 mm Hg), elevated pressure depressed GLAST expression, diminished GS activity, and induced axonal swelling between the GC layer and the inner limiting membrane. However, at the moderately elevated pressure (35 mm Hg), administration of either TFB-TBOA or MSO also induced axonal swelling and excitotoxic neuronal damage. MSO did not depress GLAST expression but TFB-TBOA significantly suppressed GS, suggesting that downregulation of GS during pressure loading may result from impaired GLAST expression. Conclusions. The retina is at risk during acute intraocular pressure elevation due to downregulation of GS activity resulting from depressed GLAST expression. PMID:21775659

Downregulation of glutamine synthetase via GLAST suppression induces retinal axonal swelling in a rat ex vivo hydrostatic pressure model.

PubMed

Ishikawa, Makoto; Yoshitomi, Takeshi; Zorumski, Charles F; Izumi, Yukitoshi

2011-08-22

PURPOSE. High levels of glutamate can be toxic to retinal GCs. Thus, effective buffering of extracellular glutamate is important in preserving retinal structure and function. GLAST, a major glutamate transporter in the retina, and glutamine synthetase (GS) regulate extracellular glutamate accumulation and prevent excitotoxicity. This study was an examination of changes in function and expression of GLAST and GS in ex vivo rat retinas exposed to acute increases in ambient pressure. METHODS. Ex vivo rat retinas were exposed to elevated hydrostatic pressure for 24 hours. The expression of GLAST and GS were examined using immunochemistry and real-time PCR analysis. Also examined were the effects of (2S,3S)-3-[3-[4-(trifluoromethyl) benzoylamino] benzyloxy] aspartate (TFB-TBOA), an inhibitor of glutamate transporters, and l-methionine-S-sulfoximine (MSO), an inhibitor of GS. RESULTS. In this acute model, Western blot and real-time RT-PCR analyses revealed that substantially (75 mm Hg), but not moderately (35 mm Hg), elevated pressure depressed GLAST expression, diminished GS activity, and induced axonal swelling between the GC layer and the inner limiting membrane. However, at the moderately elevated pressure (35 mm Hg), administration of either TFB-TBOA or MSO also induced axonal swelling and excitotoxic neuronal damage. MSO did not depress GLAST expression but TFB-TBOA significantly suppressed GS, suggesting that downregulation of GS during pressure loading may result from impaired GLAST expression. CONCLUSIONS. The retina is at risk during acute intraocular pressure elevation due to downregulation of GS activity resulting from depressed GLAST expression.

Acute arterial occlusion - kidney

MedlinePlus

... the second kidney can filter the blood. However, high blood pressure (hypertension) may come on suddenly and be difficult ... pain or pain in the side Symptoms of high blood pressure such as headache, change in vision, and swelling ...

Thermodynamic Investigation of the Interaction between Polymer and Gases

NASA Astrophysics Data System (ADS)

Mahmood, Syed Hassan

This thesis investigates the interaction between blowing agents and polymer matrix. Existing theoretical model was further developed to accommodate the polymer and blowing agent under study. The obtained results are not only useful for the optimization of the plastic foam fabrication process but also provides a different approach to usage of blowing agents. A magnetic suspension balance and an in-house visualizing dilatometer were used to obtain the sorption of blowing agents in polymer melts under elevated temperature and pressure. The proposed theoretical approach based on the thermodynamic model of SS-EOS is applied to understand the interaction of blowing agents with the polymer melt and one another (in the case of blend blowing agent). An in-depth study of the interaction of a blend of CO2 and DME with PS was conducted. Experimental volume swelling of the blend/PS mixture was measured and compared to the theoretical volume swelling obtained via ternary based SS-EOS, insuring the models validity. The effect of plasticization due to dissolution of DME on the solubility of CO2 in PS was then investigated by utilizing the aforementioned model. It was noted that the dissolution of DME increased the concentration of CO2 in PS and lowering the saturation pressure needed to dissolved a certain amount of CO2 in PS melt. The phenomenon of retrograde vitrification in PMMA induced due dissolution of CO2 was investigated in light of the thermodynamic properties resulting from the interaction of polymer and blowing agent. Solubility and volume swelling were measured in the pressure and temperature ranges promoting vitrification phenomenon, with relation being established between the thermodynamic properties and the vitrification process. Foaming of PMMA was conducted at various temperature values to investigate the application of this phenomenon.

Pressure-flow relationships in in vitro model of compartment syndrome.

PubMed

Shrier, I; Magder, S

1995-07-01

Compartment syndrome is a condition in which an increase in intramuscular pressure decreases blood flow to skeletal muscle. According to the Starling resistor (i.e., vascular waterfall) model of blood flow, the decrease in flow could occur through an increase in arterial resistance (Rart) or an increase in the critical closing pressure (Pcrit). To determine which explains the decrease in flow, we pump perfused a canine gastrocnemius muscle placed within an airtight box, controlled box pressures (Pbox) so that flow ranged from 100 to 50%, and measured Pcrit, Rart, arterial compliance, small venular pressure (measured by the double-occlusion technique), and venous pressure. An increase in Pbox limited flow mainly through an increase in Pcrit (75-85%), with only small changes in Rart (15-25%) and no change in arterial compliance. Increases in Pbox also produced a vascular waterfall in the venous circulation, but small venular transmural pressure always remained less than control levels. We conclude that increases in Pbox mostly limit blood flow through increases in Pcrit and that Rart plays a minor role. Transmural pressure across the small venules decreases with increases in intramuscular pressure, which contradicts the currently held belief that compartment syndrome is due to a cycle of swelling-ischemia-swelling.

Osmotic swelling of polyacrylate hydrogels in physiological salt solutions.

PubMed

Horkay, F; Tasaki, I; Basser, P J

2000-01-01

The swelling behavior of fully neutralized sodium polyacrylate gels was investigated in aqueous solutions of alkali metal (LiCl, NaCl, KCl, CsCl) and alkaline earth metal salts (CaCl2, SrCl2, BaCl2). The total salt concentration and the ratio of monovalent to divalent cations were varied in the biologically significant range. It is found that the concentrations of both monovalent and divalent cations vary continuously and smoothly in the gel despite the abrupt change in the gel volume. The individual elastic, mixing, and ionic contributions to the free energy of the gel were separately determined as a function of the degree of network swelling to elucidate the thermodynamics of swelling. Shear modulus measurements performed at different Ca2+ concentrations suggest that Ca2+ does not form stable cross-links between the polymer chains. At low and moderate swelling ratios the concentration dependence of the shear modulus follows a power law behavior, G variation of phi n, with n = 0.34 +/- 0.03. At high swelling degrees, however, the shear modulus increases with increasing swelling. The value of the Flory-Huggins interaction parameter, chi, determined from osmotic swelling pressure and shear modulus measurements, strongly depends on the ionic composition of the equilibrium solution and increases with increasing Ca2+ concentration.

Analysis and prediction of ocean swell using instrumented buoys

NASA Technical Reports Server (NTRS)

Mettlach, Theodore; Wang, David; Wittmann, Paul

1994-01-01

During the period 20-23 September 1990, the remnants of Supertyphoon Flo moved into the central North Pacific Ocean with sustained wind speeds of 28 m/s. The strong wind and large fetch area associated with this storm generated long-period swell that propagated to the west coast of North America. National Data Buoy Center moored-buoy stations, located in a network that ranged from the Gulf of Alaska to the California Bight, provided wave spectral estimates of the swell from this storm. The greatest dominant wave periods measured were approximately 20-25 s, and significant wave heights measured ranged from 3 to 8 m. Wave spectra from an array of three nondirectional buoys are used to find the source of the long-period swell. Directional wave spectra from a heave-pitch-roll buoy are also used to make an independent estimate of the source of the swell. The ridge-line method, using time-frequency contour plots of wave spectral energy density, is used to determine the time of swell generation, which is used with the appropriate surface pressure analysis to infer the swell generation area. The diagnosed sources of the swell are also compared with nowcasts from the Global Spectral Ocean Wave Model of the Fleet Numerical Oceanography Center. A simple method of predicting the propagation of ocean swell, by applying a simple kinematic model of wave propagation to the estimated point and time source, is demonstrated.

[Experimental study of acute brain swelling under acute intracranial hypertension (author's transl)].

PubMed

Shigemori, M; Watanabe, M; Kuramoto, S

1976-12-01

There are many problems about the cause, pathophysiology and treatment of acute brain swelling under intracranial hypertension frequently encountered in the neurosurgical clinics. Generally, rapid increase of the cerebral vasoparesis caused by unknown etiology is thought to be the main cause of acute brain swelling under intracranial hypertension. Moreover, disturbance of the cerebral venous circulatory system is discussed recently by many authors. But, research from the point of systemic respiration and hemodynamics is necessary for resolving these problems. This experiment was designed to study the effects of respiration and hemodynamics on the cerebral vasoparesis. Using 22 adult dogs, acute intracranial hypertension was produced by epidural balloon inflation sustained at the level of 300 - 400 mmH2O. Simultaneously with measurement of intracranial pressure at the epidural space, superior sagittal sinus pressure, respirogram, systemic blood pressure (femoral artery), central venous pressure, common carotid blood flow, EKG and bipolar lead EEG were monitored continuously. The experimental group was divided by the respiratory loading into 5 groups as follows: control (6 cases), 10% CO2 hypercapnia (4 cases), 10% O2 hypoxia (4 cases), stenosis of airway (5 cases), 100% O2-controled respiration (3 cases). 1) Cerebral vasoparesis under acute intracranial hypertension took place earlier and showed more rapid progression in groups of stenosis of airway, hypercapnia and hypoxia than control group of spontaneous respiration in room air. No occurrence of cerebral vasoparesis was found out in a group of 100% O2 controlled respiration. It is proved that increased airway resistance or asphyxia, hypercapnia and hypoxia have strictly reference to the occurrence and progression of cerebral vasoparesis and for the prevention of cerebral vasoparesis, correct 100% O2 cont rolled respiration is effective. 2) From the hemodynamic change, the progression of rapid increase of cerebral blood volume with increase of blood volume in the superior sagitta sinus during cerebral vasoparesis under intracranial hypertension is presumed. It is suggested from the superior sagittal sinus pressure in various experimental groups that the site, reactivity and disturbed degree of the cerebral venous system are changed by the difference of respiratory or ventrilatory state and the cerebral venous circulatory disturbance has also reference to the occurrence of acute brain swelling. 3) During cerebral vasopareris under acute intracranial hypertension, remarkable supression of respiration, increased central venous pressure and increased common carotid blood flow were observed. It is concluded that the reaction of systemic hemodynamics following respiratory change effects on cerebral circulation markedly and they are being important factors to occurrence of acute brain swelling.

Controlling the extrudate swell in melt extrusion additive manufacturing of 3D scaffolds: a designed experiment.

PubMed

Yousefi, Azizeh-Mitra; Smucker, Byran; Naber, Alex; Wyrick, Cara; Shaw, Charles; Bennett, Katelyn; Szekely, Sarah; Focke, Carlie; Wood, Katherine A

2018-02-01

Tissue engineering using three-dimensional porous scaffolds has shown promise for the restoration of normal function in injured and diseased tissues and organs. Rigorous control over scaffold architecture in melt extrusion additive manufacturing is highly restricted mainly due to pronounced variations in the deposited strand diameter upon any variations in process conditions and polymer viscoelasticity. We have designed an I-optimal, split-plot experiment to study the extrudate swell in melt extrusion additive manufacturing and to control the scaffold architecture. The designed experiment was used to generate data to relate three responses (swell, density, and modulus) to a set of controllable factors (plotting needle diameter, temperature, pressure, and the dispensing speed). The fitted regression relationships were used to optimize the three responses simultaneously. The swell response was constrained to be close to 1 while maximizing the modulus and minimizing the density. Constraining the extrudate swell to 1 generates design-driven scaffolds, with strand diameters equal to the plotting needle diameter, and allows a greater control over scaffold pore size. Hence, the modulus of the scaffolds can be fully controlled by adjusting the in-plane distance between the deposited strands. To the extent of the model's validity, we can eliminate the effect of extrudate swell in designing these scaffolds, while targeting a range of porosity and modulus appropriate for bone tissue engineering. The result of this optimization was a predicted modulus of 14 MPa and a predicted density of 0.29 g/cm 3 (porosity ≈ 75%) using polycaprolactone as scaffold material. These predicted responses corresponded to factor levels of 0.6 μm for the plotting needle diameter, plotting pressure of 2.5 bar, melt temperature of 113.5 °C, and dispensing speed of 2 mm/s. The validation scaffold enabled us to quantify the percentage difference for the predictions, which was 9.5% for the extrudate swell, 19% for the density, and 29% for the modulus.

Swelling, Structure, and Phase Stability of Soft, Compressible Microgels

NASA Astrophysics Data System (ADS)

Denton, Alan R.; Urich, Matthew

Microgels are soft colloidal particles that swell when dispersed in a solvent. The equilibrium particle size is governed by a delicate balance of osmotic pressures, which can be tuned by varying single-particle properties and externally controlled conditions, such as temperature, pH, ionic strength, and concentration. Because of their tunable size and ability to encapsulate dye or drug molecules, microgels have practical relevance for biosensing, drug delivery, carbon capture, and filtration. Using Monte Carlo simulation, we model suspensions of microgels that interact via Hertzian elastic interparticle forces and can expand or contract via trial size changes governed by the Flory-Rehner free energy of cross-linked polymer gels. We analyze the influence of particle compressibility and size fluctuations on bulk structural and thermal properties by computing swelling ratios, radial distribution functions, static structure factors, osmotic pressures, and freezing densities. With increasing density, microgels progressively deswell and their intrinsic polydispersity broadens, while compressibility acts to forestall crystallization. This work was supported by the National Science Foundation under Grant No. DMR- 1106331.

A novel hydrogel based piezoresistive pressure sensor platform for chemical sensing

NASA Astrophysics Data System (ADS)

Orthner, Michael P.

New hydrogel-based micropressure sensor arrays for use in the fields of chemical sensing, physiological monitoring, and medical diagnostics are developed and demonstrated. This sensor technology provides reliable, linear, and accurate measurements of hydrogel swelling pressures, a function of ambient chemical concentrations. For the first time, perforations were implemented into the pressure sensors piezoresistive diaphragms, used to simultaneously increase sensor sensitivity and permit diffusion of analytes into the hydrogel cavity. It was shown through analytical and numerical (finite element) methods that pore shape, location, and size can be used to modify the diaphragm mechanics and concentrate stress within the piezoresistors, thus improving electrical output (sensitivity). An optimized pore pattern was chosen based on these numerical calculations. Fabrication was performed using a 14-step semiconductor fabrication process implementing a combination of potassium hydroxide (KOH) and deep reactive ion etching (DRIE) to create perforations. The sensor arrays (2x2) measure approximately 3 x 5 mm2 and used to measure full scale pressures of 50, 25, and 5 kPa, respectively. These specifications were defined by the various swelling pressures of ionic strength, pH and glucose specific hydrogels that were targeted in this work. Initial characterization of the sensor arrays was performed using a custom built bulge testing apparatus that simultaneously measured deflection (optical profilometry), pressure, and electrical output. The new perforated diaphragm sensors were found to be fully functional with sensitivities ranging from 23 to 252 muV/V-kPa with full scale output (FSO) ranging from 5 to 80 mV. To demonstrate proof of concept, hydrogels sensitive to changes in ionic strength were synthesized using hydroxypropyl-methacrylate (HPMA), N,N-dimethylaminoethyl-methacrylate (DMA) and a tetra-ethyleneglycol-dimethacrylate (TEGDMA) crosslinker. This hydrogel quickly and reversibly swells when placed environments of physiological buffer solutions (PBS) with ionic strengths ranging from 0.025 to 0.15 M. Chemical testing showed sensors with perforated diaphragms have higher sensitivity than those with solid diaphragms, and sensitivities ranging from 53.3+/-6.5 to 271.47+/-27.53 mV/V-M, depending on diaphragm size. Additionally, recent experiments show sensors utilizing Ultra Violet (UV) polymerized glucose sensitive hydrogels respond reversibly to physiologically relevant glucose concentrations from 0 to 20 mM.

Pathophysiology of cerebral oedema in acute liver failure.

PubMed

Scott, Teresa R; Kronsten, Victoria T; Hughes, Robin D; Shawcross, Debbie L

2013-12-28

Cerebral oedema is a devastating consequence of acute liver failure (ALF) and may be associated with the development of intracranial hypertension and death. In ALF, some patients may develop cerebral oedema and increased intracranial pressure but progression to life-threatening intracranial hypertension is less frequent than previously described, complicating less than one third of cases who have proceeded to coma since the advent of improved clinical care. The rapid onset of encephalopathy may be dramatic with the development of asterixis, delirium, seizures and coma. Cytotoxic and vasogenic oedema mechanisms have been implicated with a preponderance of experimental data favouring a cytotoxic mechanism. Astrocyte swelling is the most consistent neuropathological finding in humans with ALF and ammonia plays a definitive role in the development of cytotoxic brain oedema. The mechanism(s) by which ammonia induces astrocyte swelling remains unclear but glutamine accumulation within astrocytes has led to the osmolyte hypothesis. Current evidence also supports an alternate 'Trojan horse' hypothesis, with glutamine as a carrier of ammonia into mitochondria, where its accumulation results in oxidative stress, energy failure and ultimately astrocyte swelling. Although a complete breakdown of the blood-brain barrier is not evident in human ALF, increased permeation to water and other small molecules such as ammonia has been demonstrated resulting from subtle alterations in the protein composition of paracellular tight junctions. At present, there is no fully efficacious therapy for cerebral oedema other than liver transplantation and this reflects our incomplete knowledge of the precise mechanisms underlying this process which remain largely unknown.

An experimental study of the effects of adsorbing and non-adsorbing gases on friction and permeability evolution in clay-rich fault gouge

NASA Astrophysics Data System (ADS)

Lisabeth, H. P.; Zoback, M. D.

2017-12-01

Understanding the flow of fluids through fractures in clay-rich rocks is fundamental to a number of geoengineering enterprises, including development of unconventional hydrocarbon resources, nuclear waste storage and geological carbon sequestration. High clay content tends to make rocks plastic, low-porosity and anisotropic. In addition, some gasses adsorb to clay mineral surfaces, resulting in swelling and concomitant changes in physical properties. These complexities can lead to coupled behaviors that render prediction of fluid behavior in the subsurface difficult. We present the results of a suite of triaxial experiments on binary mixtures of quartz and illite grains to separate and quantify the effects of hydrostatic pressure, differential stress, clay content and gas chemistry on the evolution of mechanical and hydraulic characteristics of the gouge material during deformation. Tests are run on saw-cut samples prepared with gouge at 20 MPa confining pressure, 10 MPa pore pressure and at room temperature. Argon or carbon dioxide is used as pore fluid. Sample permeability, stress and strain are monitored continuously during hydrostatic and axial deformation. We find that pressure and shearing both lead to reductions in permeability. Adsorbing gas leads to swelling and promotes permeability reduction, but appears to have no effect on frictional properties. These results indicate that the seal integrity of clay-rich caprocks may not be compromised by shear deformation, and that depletion and shear deformation of unconventional reservoirs is expected to result in production declines.

Unpredicted spontaneous extrusion of a renal calculus in an adult male with spina bifida and paraplegia: report of a misdiagnosis. Measures to be taken to reduce urological errors in spinal cord injury patients

PubMed Central

Vaidyanathan, Subramanian; Hughes, Peter L; Soni, Bhakul M; Singh, Gurpreet; Mansour, Paul; Sett, Pradipkumar

2001-01-01

Background A delay in diagnosis or a misdiagnosis may occur in patients with spinal cord injury (SCI) or spinal bifida as typical symptoms of a clinical condition may be absent because of their neurological impairment. Case presentation A 29-year old male, who was born with spina bifida and hydrocephalus, became unwell and developed a swelling and large red mark in his left loin eighteen months ago. Pyonephrosis or perinephric abscess was suspected. X-ray of the abdomen showed left-sided staghorn calculus. Since ultrasound scan showed no features of pyonephrosis or perinephric abscess, he was prescribed a prolonged course of antibiotics for infection presumed to arise from the site of metal implant in spine. He developed a discharging sinus, following which the loin swelling and red mark subsided. About three months ago, he again developed a red mark and minimal swelling in the left loin. Ultrasound scan detected no abnormality in the renal or perinephric region. Therefore, the red mark and swelling were attributed to pressure from the backrest of his chair. Five weeks later, the swelling in the left loin burst open and a large stone was extruded spontaneously. An X-ray of the abdomen showed that he had extruded the central portion of the staghorn calculus from left kidney. With hindsight, the extruded renal calculus could be seen lying in the subcutaneous tissue of left loin lateral to the 10th rib in the X-ray of abdomen, which was taken when he presented with red mark and minimal swelling. Conclusion This case illustrates how mistakes in diagnosis could occur in spinal cord injury patients, and highlights the need for corrective measures to reduce urological errors in these patients. Voluntary reporting of urological errors is recommended to facilitate learning from our mistakes. In the patients who have marked spinal curvature, ultrasonography of kidneys and perinephric region may not be entirely reliable. As clinical symptoms and signs may be non-specific in SCI patients, they require prompt, detailed and occasionally, repeated investigations. A joint team approach by health professionals belonging to various medical disciplines, which is strengthened by frequent, informal and honest discussions of a patient's clinical condition, is likely to reduce urological errors in SCI patients. PMID:11801198

Study of swelling behavior in ArF resist during development by the QCM method (3): observations of swelling layer elastic modulus

NASA Astrophysics Data System (ADS)

Sekiguchi, Atsushi

2013-03-01

The QCM method allows measurements of impedance, an index of swelling layer viscosity in a photoresist during development. While impedance is sometimes used as a qualitative index of change in the viscosity of the swelling layer, it has to date not been used quantitatively, for data analysis. We explored a method for converting impedance values to elastic modulus (Pa), a coefficient expressing viscosity. Applying this method, we compared changes in the viscosity of the swelling layer in an ArF resist generated during development in a TMAH developing solution and in a TBAH developing solution. This paper reports the results of this comparative study.

Microfluidic diffusivity meter: a tool to optimize CO2 driven enhanced oil recovery

NASA Astrophysics Data System (ADS)

Puneeth, S. B.; Kim, Young Ho; Goel, Sanket

2017-02-01

As the energy demands continue to swell with growing population and there persists a lack of unexploited oilfields, the prime focus of any nation would be to maximize the oil recovery factor from existing oil fields. CO2-Enhanced oil recovery is a process to improve the recovery of crude oil from an oil field and works at high pressure and in very deep conditions. CO2 and oil are miscible at high pressure, resulting in low viscosity and oil swells. This swelling can be measured based on mathematical calculations in real time and correlated with the CO2 concentration. This process has myriad advantages over its counterparts which include being able to harness oil trapped in reservoirs besides being cheaper and more efficient. A Diffusivity meter is inevitable in the measurement of the diffusion co-efficient of two samples. Diffusivity meters currently available in the market are weighed down by disadvantages like the requirement of large samples for testing, high cost and complexity. This elicits the need for a Microfluidic based diffusivity meter capable of analyzing Nano-liter sample volumes besides being more precise and affordable. The scope of this work involves the design and development of a Microfluidic robust and inexpensive prototype diffusivity meter using a capillary tube and endorsing its performance by comparison of results with known diffusivity range and supervision of the results with an electronic microscope coupled to PC and Data Acquisition System. The prototype produced at the end of the work is expected to outweigh disadvantages in existing products in terms of sample size, efficiency and time saving.

Amino Acid-Based Material for the Complementary Therapy of Decubitus Ulcers.

PubMed

Nogueira, Frederico; Gouveia, Isabel C

2017-04-28

Chronic wounds, pressure sores, lesions, and infections of microbial origin in bedridden, paralyzed, or malnutrition patients remain the object of study of many researchers. A variety of factors behind the development of these disorders are related to the patient's immune system, making it unable to respond effectively to the treatment of the wound. These factors can be properly controlled, giving particular importance to the ethiology and stage of the wound, as well as the time periods corresponding to the replacement of the dressings. The present research reports a novel foam/soft material, L -Cys-g-PCL, with an application for decubitus/pressure ulcers, especially for wounds with a difficult healing process due to infections and constant oxidation of the soft tissues. During this work, the interactions between S. aureus and L -Cys-g-PCL foam were studied under conditions that simulate decubitus ulcers; namely, pH and exudate. The effects of duration of grafting (1 or 8 h) and pH (7.0 and 8.9) on wettability, surface energy, swelling, and porosity were also evaluated. Results showed an effective microbicidal activity exhibiting an inhibition ratio of 99.73% against S. aureu s. This new L -Cys-g-PCL soft material showed saftey to contact skin, ability to be shaped to fill in sunken holes (craters) - pressure ulcers stage III - and to act as a smart material responsive to pH, which can be tailored to develop better swelling properties at alkaline pH where exudates are normally higher, so as to address exudate self-cleaning and prevention of desiccation..

Recombinant human hyaluronidase PH20 (rHuPH20) facilitates subcutaneous infusions of large volumes of immunoglobulin in a swine model.

PubMed

Kang, David W; Jadin, Laurence; Nekoroski, Tara; Drake, Fred H; Zepeda, Monica L

2012-08-01

Many patients with primary immunodeficiency disease (PIDD) require lifelong immunoglobulin (Ig) replacement therapy. Home-based subcutaneous (SC) infusion provides advantages to patients with PIDD compared to hospital-based intravenous infusion. One limitation of current practice with SCIg infusion is the need for small-volume infusions at multiple injection sites on a frequent basis. A method was developed for large-volume SC infusion that uses preinfusion of recombinant human hyaluronidase (rHuPH20) to facilitate fluid dispersion. Miniature swine was used as a preclinical model to assess the effects of rHuPH20-facilitated infusions, of a single monthly dose, on fluid dispersion, infusion-related pressure, swelling, induration, and tissue damage. Preinfusion of vehicle (control) or rHuPH20 (75 U/g Ig) was performed simultaneously on contralateral abdominal sites on each animal, followed by infusion of 300 mL 10 % Ig (30 g) at each site. Compared to control infusions, rHuPH20 significantly reduced infusion pressure and induration (p < 0.05) and accelerated postinfusion Ig dispersion. Histological evaluation of infusion site tissue showed moderate to severe swelling for the control. Swelling after rHuPH20-facilitated infusion was mild on day 1 and had completely resolved shortly thereafter. Laser Doppler imaging of control infusion sites revealed local cutaneous hypoperfusion during Ig infusion, which was reduced almost 7-fold (p < 0.05) with the use of rHuPH20. These results demonstrate that rHuPH20-facilitated Ig infusion is associated with improved dispersion of Ig, resulting in reduced tissue pressure, induration, and reduced risk of tissue damage from mechanical trauma or local ischemia, thus enabling SC administration of large volumes of Ig at a single site.

A molecular model of proteoglycan-associated electrostatic forces in cartilage mechanics.

PubMed

Buschmann, M D; Grodzinsky, A J

1995-05-01

Measured values of the swelling pressure of charged proteoglycans (PG) in solution (Williams RPW, and Comper WD; Biophysical Chemistry 36:223, 1990) and the ionic strength dependence of the equilibrium modulus of PG-rich articular cartilage (Eisenberg SR, and Grodzinsky AJ; J Orthop Res 3: 148, 1985) are compared to the predictions of two models. Each model is a representation of electrostatic forces arising from charge present on spatially fixed macromolecules and spatially mobile micro-ions. The first is a macroscopic continuum model based on Donnan equilibrium that includes no molecular-level structure and assumes that the electrical potential is spatially invariant within the polyelectrolyte medium (i.e. zero electric field). The second model is based on a microstructural, molecular-level solution of the Poisson-Boltzmann (PB) equation within a unit cell containing a charged glycosaminoglycan (GAG) molecule and its surrounding atmosphere of mobile ions. This latter approach accounts for the space-varying electrical potential and electrical field between the GAG constituents of the PG. In computations involving no adjustable parameters, the PB-cell model agrees with the measured pressure of PG solutions to within experimental error (10%), whereas the ideal Donnan model overestimates the pressure by up to 3-fold. In computations involving one adjustable parameter for each model, the PB-cell model predicts the ionic strength dependence of the equilibrium modulus of articular cartilage. Near physiological ionic strength, the Donnan model overpredicts the modulus data by 2-fold, but the two models coincide for low ionic strengths (C0 < 0.025M) where the spatially invariant Donnan potential is a closer approximation to the PB potential distribution. The PB-cell model result indicates that electrostatic forces between adjacent GAGs predominate in determining the swelling pressure of PG in the concentration range found in articular cartilage (20-80 mg/ml). The PB-cell model is also consistent with data (Eisenberg and Grodzinsky, 1985, Lai WM, Hou JS, and Mow VC; J Biomech Eng 113: 245, 1991) showing that these electrostatic forces account for approximately 1/2 (290kPa) the equilibrium modulus of cartilage at physiological ionic strength while absolute swelling pressures may be as low as approximately 25-100kPa. This important property of electrostatic repulsion between GAGs that are highly charged but spaced a few Debye lengths apart allows cartilage to resist compression (high modulus) without generating excessive intratissue swelling pressures.

Determination of the parameters controlling swelling of chemically cross-linked pH-sensitive poly(N-vinylimidazole) hydrogels.

PubMed

Molina, M Jesús; Gómez-Antón, M Rosa; Piérola, Inés F

2007-10-25

The number of variables controlling the behavior of ionic gels is large and very often some of them are unknown. The aim of this work is to interpret quantitatively the swelling behavior of pH sensitive gels, with the minimum number of simplifying assumptions. With this purpose, the equilibrium degree of swelling (S) and protonation (alpha) of chemically cross-linked poly(N-vinylimidazole) (PVI) immersed in aqueous salt solutions were measured as a function of the ionic strength (mu), in the whole range of pH. In acid solutions with pH in the range 0 to 4, imidazole moieties become protonated, and PVI behaves as a polyelectrolyte gel: S decreases upon increasing mu both for NaCl and for CaCl(2), with HCl as protonating acid. In aqueous solutions with larger pH, between 4 and 12, the hydrogel is practically neutral, and S increases as mu rises, showing a salting-in effect. From the quantitative analysis of these results, the following facts emerged. Protonation induces chain stiffness (as measured by the non-Gaussian factor) and worsening of the solvent quality of the aqueous media (as measured by the polymer-solvent interaction parameter). For alpha below 33%, swelling seems to be governed by the excess of mobile counterions inside the gel with respect to the bath, with a minor but still significantly negative contribution of the osmotic swelling pressure due to polymer-solvent mixing. Above 33% protonation, it is necessary to consider Manning counterion condensation to get parameters with physical meaning. The crossover between polyelectrolyte and salting-in effects corresponds to alpha and mu values with the same ionic and mixing contributions to the osmotic swelling pressure. The formation of ionic nonpermanent cross-links, with H(2)SO(4) as the protonating acid, was discarded.

Effects of osmotic pressure in the extracellular matrix on tissue deformation.

PubMed

Lu, Y; Parker, K H; Wang, W

2006-06-15

In soft tissues, large molecules such as proteoglycans trapped in the extracellular matrix (ECM) generate high levels of osmotic pressure to counter-balance external pressures. The semi-permeable matrix and fixed negative charges on these molecules serve to promote the swelling of tissues when there is an imbalance of molecular concentrations. Structural molecules, such as collagen fibres, form a network of stretch-resistant matrix, which prevents tissue from over-swelling and keeps tissue integrity. However, collagen makes little contribution to load bearing; the osmotic pressure in the ECM is the main contributor balancing external pressures. Although there have been a number of studies on tissue deformation, there is no rigorous analysis focusing on the contribution of the osmotic pressure in the ECM on the viscoelastic behaviour of soft tissues. Furthermore, most previous works were carried out based on the assumption of infinitesimal deformation, whereas tissue deformation is finite under physiological conditions. In the current study, a simplified mathematical model is proposed. Analytic solutions for solute distribution in the ECM and the free-moving boundary were derived by solving integro-differential equations under constant and dynamic loading conditions. Osmotic pressure in the ECM is found to contribute significantly to the viscoelastic characteristics of soft tissues during their deformation.

Benchtop-magnetic resonance imaging (BT-MRI) characterization of push-pull osmotic controlled release systems.

PubMed

Malaterre, Vincent; Metz, Hendrik; Ogorka, Joerg; Gurny, Robert; Loggia, Nicoletta; Mäder, Karsten

2009-01-05

The mechanism of drug release from push-pull osmotic systems (PPOS) has been investigated by Magnetic Resonance Imaging (MRI) using a new benchtop apparatus. The signal intensity profiles of both PPOS layers were monitored non-invasively over time to characterize the hydration and swelling kinetics. The drug release performance was well-correlated to the hydration kinetics. The results show that (i) hydration and swelling critically depend on the tablet core composition, (ii) high osmotic pressure developed by the push layer may lead to bypassing the drug layer and incomplete drug release and (iii) the hydration of both the drug and the push layers needs to be properly balanced to efficiently deliver the drug. MRI is therefore a powerful tool to get insights on the drug delivery mechanism of push-pull osmotic systems, which enable a more efficient optimization of such formulations.

Pathophysiology of cerebral oedema in acute liver failure

PubMed Central

Scott, Teresa R; Kronsten, Victoria T; Hughes, Robin D; Shawcross, Debbie L

2013-01-01

Cerebral oedema is a devastating consequence of acute liver failure (ALF) and may be associated with the development of intracranial hypertension and death. In ALF, some patients may develop cerebral oedema and increased intracranial pressure but progression to life-threatening intracranial hypertension is less frequent than previously described, complicating less than one third of cases who have proceeded to coma since the advent of improved clinical care. The rapid onset of encephalopathy may be dramatic with the development of asterixis, delirium, seizures and coma. Cytotoxic and vasogenic oedema mechanisms have been implicated with a preponderance of experimental data favouring a cytotoxic mechanism. Astrocyte swelling is the most consistent neuropathological finding in humans with ALF and ammonia plays a definitive role in the development of cytotoxic brain oedema. The mechanism(s) by which ammonia induces astrocyte swelling remains unclear but glutamine accumulation within astrocytes has led to the osmolyte hypothesis. Current evidence also supports an alternate ‘Trojan horse’ hypothesis, with glutamine as a carrier of ammonia into mitochondria, where its accumulation results in oxidative stress, energy failure and ultimately astrocyte swelling. Although a complete breakdown of the blood-brain barrier is not evident in human ALF, increased permeation to water and other small molecules such as ammonia has been demonstrated resulting from subtle alterations in the protein composition of paracellular tight junctions. At present, there is no fully efficacious therapy for cerebral oedema other than liver transplantation and this reflects our incomplete knowledge of the precise mechanisms underlying this process which remain largely unknown. PMID:24409052

Simulation and evaluation of rupturable coated capsules by finite element method.

PubMed

Yang, Yan; Fang, Jie; Shen, Lian; Shan, Weiguang

2017-03-15

The objective of this study was to simulate and evaluate the burst behavior of rupturable coated capsules by finite element method (FEM). Film and coated capsules were prepared by dip-coating method and their dimensions were determined by stereomicroscope. Mechanical properties of the film were measured by tensile test and used as material properties of FEM models. Swelling pressure was determined by restrained expansion method and applied to the internal surface of FEM models. Water uptake of coated capsules was determined to study the formation of internal pressure. Burst test and in vitro dissolution was used to verify the FEM models, which were used to study and predict the coating burst behavior. Simulated results of coating burst behavior were well agreed with the experiment results. Swelling pressure, material properties and dimensions of coating had influence on the maximum stress. Burst pressure and critical L-HPC content were calculated for burst prediction and formulation optimization. FEM simulation was a feasible way to simulate and evaluate the burst behavior of coated capsules. Copyright © 2017 Elsevier B.V. All rights reserved.

Muscle changes with eccentric exercise: Implications on earth and in space

NASA Technical Reports Server (NTRS)

Hargens, Alan R.; Parazynski, Scott; Aratow, Michael; Friden, Jan

1989-01-01

Recent investigations of fluid pressure, morpholo gy, and enzyme activities of skeletal muscle exercised eccentrically or concentrically in normal human subjects are reviewed. Intramuscular pressures were measured before, during, and after submaximal exercise and correlated with subjective muscle soreness, fiber size, water content, and blood indices of muscle enzymes. High intensity eccentric exercise is characterized by post exercise pain, elevated intramuscular pressures, and swelling of both type 1 and 2 fibers as compared to concentric exercise. Thus, long periods of unaccustomed, high level eccentric contraction may cause muscle injury, fiber swelling, fluid accumulation, elevated intramuscular pressure, and delayed muscle soreness. Training regimens of progressively increasing eccentric exercise, however, cause less soreness and are extremely efficacious in increasing muscle mass and strength. It is proposed that on Earth, postural muscles are uniquely adapted to low levels of prolonged eccentric contraction that are absent during weightlessness. The almost complete absence of eccentric exercise in space may be an important contributor to muscle atrophy and therefore equipment should be designed to integrate eccentric contractions into exercise protocols for long-term spaceflight.

Acute Parotitis as a Complication of Noninvasive Ventilation.

PubMed

Alaya, S; Mofredj, Ali; Tassaioust, K; Bahloul, H; Mrabet, A

2016-09-01

Several conditions, including oropharyngeal dryness, pressure sores, ocular irritation, epistaxis, or gastric distension, have been described during noninvasive ventilation (NIV). Although this technique has been widely used in intensive care units and emergency wards, acute swelling of the parotid gland remains a scarcely reported complication. We describe herein the case of an 82-year-old man who developed unilateral parotitis during prolonged NIV for acute heart failure. Intravenous antibiotics, corticosteroids, and adjusting the mask laces' position allowed rapid resolution of clinical symptoms. © The Author(s) 2016.

Detecting self-ion irradiation-induced void swelling in pure copper using transient grating spectroscopy

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

Dennett, C. A.; So, K. P.; Kushima, A.

Irradiation-induced void swelling remains a major challenge to nuclear reactor operation. Swelling may take years to initiate and often results in rapid material property degradation once started. Alloy development for advanced nuclear systems will require rapid characterization of the swelling breakaway dose in new alloys, yet this capability does not yet exist. In this paper, we demonstrate that transient grating spectroscopy (TGS) can detect void swelling in single crystal copper via changes in surface acoustic wave (SAW) velocity. Scanning transmission electron microscopy (STEM) links the TGS-observed changes with void swelling-induced microstructural evolution. Finally, these results are considered in the contextmore » of previous work to suggest that in situ TGS will be able to rapidly determine when new bulk materials begin void swelling, shortening alloy development and testing times.« less

Detecting self-ion irradiation-induced void swelling in pure copper using transient grating spectroscopy

DOE PAGES

Dennett, C. A.; So, K. P.; Kushima, A.; ...

2017-12-20

Irradiation-induced void swelling remains a major challenge to nuclear reactor operation. Swelling may take years to initiate and often results in rapid material property degradation once started. Alloy development for advanced nuclear systems will require rapid characterization of the swelling breakaway dose in new alloys, yet this capability does not yet exist. In this paper, we demonstrate that transient grating spectroscopy (TGS) can detect void swelling in single crystal copper via changes in surface acoustic wave (SAW) velocity. Scanning transmission electron microscopy (STEM) links the TGS-observed changes with void swelling-induced microstructural evolution. Finally, these results are considered in the contextmore » of previous work to suggest that in situ TGS will be able to rapidly determine when new bulk materials begin void swelling, shortening alloy development and testing times.« less

Extracellular-matrix-mediated osmotic pressure drives Vibrio cholerae biofilm expansion and cheater exclusion.

PubMed

Yan, Jing; Nadell, Carey D; Stone, Howard A; Wingreen, Ned S; Bassler, Bonnie L

2017-08-23

Biofilms, surface-attached communities of bacteria encased in an extracellular matrix, are a major mode of bacterial life. How the material properties of the matrix contribute to biofilm growth and robustness is largely unexplored, in particular in response to environmental perturbations such as changes in osmotic pressure. Here, using Vibrio cholerae as our model organism, we show that during active cell growth, matrix production enables biofilm-dwelling bacterial cells to establish an osmotic pressure difference between the biofilm and the external environment. This pressure difference promotes biofilm expansion on nutritious surfaces by physically swelling the colony, which enhances nutrient uptake, and enables matrix-producing cells to outcompete non-matrix-producing cheaters via physical exclusion. Osmotic pressure together with crosslinking of the matrix also controls the growth of submerged biofilms and their susceptibility to invasion by planktonic cells. As the basic physicochemical principles of matrix crosslinking and osmotic swelling are universal, our findings may have implications for other biofilm-forming bacterial species.Most bacteria live in biofilms, surface-attached communities encased in an extracellular matrix. Here, Yan et al. show that matrix production in Vibrio cholerae increases the osmotic pressure within the biofilm, promoting biofilm expansion and physical exclusion of non-matrix producing cheaters.

Properties of lotus seed starch-glycerin monostearin complexes formed by high pressure homogenization.

PubMed

Chen, Bingyan; Zeng, Shaoxiao; Zeng, Hongliang; Guo, Zebin; Zhang, Yi; Zheng, Baodong

2017-07-01

Starch-lipid complexes were prepared using lotus seed starch (LS) and glycerin monostearate (GMS) via a high pressure homogenization (HPH) process, and the effect of HPH on the physicochemical properties of LS-GMS complexes was investigated. The results of Fourier transform infrared spectroscopy and complex index analysis showed that LS-GMS complexes were formed at 40MPa by HPH and the complex index increased with the increase of homogenization pressure. Scanning electron microscopy displayed LS-GMS complexes present more nest-shape structure with increasing homogenization pressure. X-ray diffraction and differential scanning calorimetry results revealed that V-type crystalline polymorph was formed between LS and GMS, with higher homogenization pressure producing an increasingly stable complex. LS-GMS complex inhibited starch granules swelling, solubility and pasting development, which further reduced peak and breakdown viscosity. During storage, LS-GMS complexes prepared by 70-100MPa had higher Avrami exponent values and lower recrystallization rates compared with native starch, which suggested a lower retrogradation trendency. Copyright © 2017 Elsevier Ltd. All rights reserved.

MOELCULAR SIZE EXCLUSION BY SOIL ORGANIC MATERIALS ESTIMATED FROM THEIR SWELLING IN ORGANIC SOLVENTS

EPA Science Inventory

A published method previously developed to measure the swelling characteristics of pow dered coal samples has been adapted for swelling measurements on various peat, pollen, chain, and cellulose samples The swelling of these macromolecular materials is the volumetric manifestatio...

MOLECULAR SIZE EXCLUSION BY SOIL ORGANIC MATERIALS ESTIMATED FROM THEIR SWELLING IN ORGANIC SOLVENTS

EPA Science Inventory

A published method previously developed to measure the swelling characteristics of powdered coal samples has been adapted for swelling measurements on various peat, pollen, chitin, and cellulose samples. he swelling of these macromolecular materials is the volumetric manifestatio...

Low-load resistance training with low relative pressure produces muscular changes similar to high-load resistance training.

PubMed

Kim, Daeyeol; Loenneke, Jeremy P; Ye, Xin; Bemben, Debra A; Beck, Travis W; Larson, Rebecca D; Bemben, Michael G

2017-12-01

This study compares the acute and chronic response of high-load resistance training (HL) to low-load resistance training with low blood flow restriction (LL-BFR) pressure. Participants completed elbow flexion with either HL or LL-BFR or nonexercise. In the chronic study, participants in the HL and LL-BFR groups were trained for 8 weeks to determine differences in muscle size and strength. The acute study examined the changes in pretesting/posttesting (Pre/Post) torque, muscle swelling, and blood lactate. In the chronic study, similar changes in muscle size and strength were observed for both HL and LL-BFR. In the acute study, Pre/Post changes in the torque, muscle swelling, and blood lactate were similar between HL and LL-BFR. Our findings indicate that pressure as low as 50% arterial occlusion can produce similar changes in muscle mass and strength compared with traditional HL. Muscle Nerve 56: E126-E133, 2017. © 2017 Wiley Periodicals, Inc.

Decoupling of mass transport mechanisms in the stagewise swelling of multiple emulsions.

PubMed

Bahtz, Jana; Gunes, Deniz Z; Hughes, Eric; Pokorny, Lea; Riesch, Francesca; Syrbe, Axel; Fischer, Peter; Windhab, Erich J

2015-05-19

This contribution reports on the mass transport kinetics of osmotically imbalanced water-in-oil-in-water (W1/O/W2) emulsions. Although frequently studied, the control of mass transport in W1/O/W2 emulsions is still challenging. We describe a microfluidics-based method to systematically investigate the impact of various parameters, such as osmotic pressure gradient, oil phase viscosity, and temperature, on the mass transport. Combined with optical microscopy analyses, we are able to identify and decouple the various mechanisms, which control the dynamic droplet size of osmotically imbalanced W1/O/W2 emulsions. So, swelling kinetics curves with a very high accuracy are generated, giving a basis for quantifying the kinetic aspects of transport. Two sequential swelling stages, i.e., a lag stage and an osmotically dominated stage, with different mass transport mechanisms are identified. The determination and interpretation of the different stages are the prerequisite to control and trigger the swelling process. We show evidence that both mass transport mechanisms can be decoupled from each other. Rapid osmotically driven mass transport only takes place in a second stage induced by structural changes of the oil phase in a lag stage, which allow an osmotic exchange between both water phases. Such structural changes are strongly facilitated by spontaneous water-in-oil emulsification. The duration of the lag stage is pressure-independent but significantly influenced by the oil phase viscosity and temperature.

Self-healing mortar with pH-sensitive superabsorbent polymers: testing of the sealing efficiency by water flow tests

NASA Astrophysics Data System (ADS)

Gruyaert, Elke; Debbaut, Brenda; Snoeck, Didier; Díaz, Pilar; Arizo, Alejandro; Tziviloglou, Eirini; Schlangen, Erik; De Belie, Nele

2016-08-01

Superabsorbent polymers (SAPs) have potential to be used as healing agent in self-healing concrete due to their property to attract moisture from the environment and their capacity to promote autogenous healing. A possible drawback, however, is their uptake of mixing water during concrete manufacturing, resulting in an increased volume of macro-pores in the hardened concrete. To limit this drawback, newly developed SAPs with a high swelling and pH-sensitiveness were developed and tested within the FP7 project HEALCON. Evaluation of their self-sealing performance occurred through a water permeability test via water flow, a test method also developed within HEALCON. Three different sizes of the newly developed SAP were compared with a commercial SAP. Swelling tests in cement filtrate solution indicated that the commercial and in-house synthesized SAPs performed quite similar, but the difference between the swelling capacity at pH 9 and pH 13 is more pronounced for the self-synthesized SAPs. Moreover, in comparison to the commercial SAPs, less macro-pores are formed in the cement matrix of mixes with self-synthesized SAPs and the effect on the mechanical properties is lower, but not negligible, when using high amounts of SAPs. Although the immediate sealing effect of cracks in mortar was the highest for the commercial SAPs, the in-house made SAPs with a particle size between 400 and 600 μm performed the best with regard to crack closure (mainly CaCO3 precipitation) and self-sealing efficiency, after exposing the specimens to 28 wet-dry cycles. Some specimens could even withstand a water pressure of 2 bar.

Exposure of natural rubber to personal lubricants--swelling and stress relaxation as potential indicators of reduced seal integrity of non-lubricated male condoms.

PubMed

Sarkar Das, Srilekha; Coburn, James C; Tack, Charles; Schwerin, Matthew R; Richardson, D Coleman

2014-07-01

Male condoms act as mechanical barriers to prevent passage of body fluids. For effective use of condoms the mechanical seal is also expected to remain intact under reasonable use conditions, including with personal lubricants. Absorption of low molecular weight lubricant components into the material of male condoms may initiate material changes leading to swelling and stress relaxation of the polymer network chains that could affect performance of the sealing function of the device. Swelling indicates both a rubber-solvent interaction and stress relaxation, the latter of which may indicate and/or result in a reduced seal pressure in the current context. Swelling and stress relaxation of natural rubber latex condoms were assessed in a laboratory model in the presence of silicone-, glycol-, and water-based lubricants. Within 15 minutes, significant swelling (≥6 %) and stress reduction (≥12 %) of condoms were observed with 2 out of 4 silicone-based lubricants tested, but neither was observed with glycol- or water-based lubricants tested. Under a given strain, reduction in stress was prominent during the swelling processes, but not after the process was complete. Lubricant induced swelling and stress relaxation may loosen the circumferential stress responsible for the mechanical seal. Swelling and stress relaxation behavior of latex condoms in the presence of personal lubricants may be useful tests to identify lubricant-rooted changes in condom-materials. For non-lubricated latex condoms, material characteristics--which are relevant to failure--may change in the presence of a few silicone-based personal lubricants. These changes may in turn induce a loss of condom seal during use, specifically at low strain conditions. Published by Elsevier Inc.

Increased toll-like receptor 4 in cerebral endothelial cells contributes to the astrocyte swelling and brain edema in acute hepatic encephalopathy.

PubMed

Jayakumar, Arumugam R; Tong, Xiao Y; Curtis, Kevin M; Ruiz-Cordero, Roberto; Abreu, Maria T; Norenberg, Michael D

2014-03-01

Astrocyte swelling and the subsequent increase in intracranial pressure and brain herniation are major clinical consequences in patients with acute hepatic encephalopathy. We recently reported that conditioned media from brain endothelial cells (ECs) exposed to ammonia, a mixture of cytokines (CKs) or lipopolysaccharide (LPS), when added to astrocytes caused cell swelling. In this study, we investigated the possibility that ammonia and inflammatory agents activate the toll-like receptor 4 (TLR4) in ECs, resulting in the release of factors that ultimately cause astrocyte swelling. We found a significant increase in TLR4 protein expression when ECs were exposed to ammonia, CKs or LPS alone, while exposure of ECs to a combination of these agents potentiate such effects. In addition, astrocytes exposed to conditioned media from TLR4-silenced ECs that were treated with ammonia, CKs or LPS, resulted in a significant reduction in astrocyte swelling. TLR4 protein up-regulation was also detected in rat brain ECs after treatment with the liver toxin thioacetamide, and that thioacetamide-treated TLR4 knock-out mice exhibited a reduction in brain edema. These studies strongly suggest that ECs significantly contribute to the astrocyte swelling/brain edema in acute hepatic encephalopathy, likely as a consequence of increased TLR4 protein expression by blood-borne noxious agents. © 2013 International Society for Neurochemistry.

Ophthalmodynamometry for ICP prediction and pilot test on Mt. Everest.

PubMed

Querfurth, Henry W; Lieberman, Philip; Arms, Steve; Mundell, Steve; Bennett, Michael; van Horne, Craig

2010-11-01

A recent development in non-invasive techniques to predict intracranial pressure (ICP) termed venous ophthalmodynamometry (vODM) has made measurements in absolute units possible. However, there has been little progress to show utility in the clinic or field. One important application would be to predict changes in actual ICP during adaptive responses to physiologic stress such as hypoxia. A causal relationship between raised intracranial pressure and acute mountain sickness (AMS) is suspected. Several MRI studies report that modest physiologic increases in cerebral volume, from swelling, normally accompany subacute ascent to simulated high altitudes. 1) Validate and calibrate an advanced, portable vODM instrument on intensive patients with raised intracranial pressure and 2) make pilot, non-invasive ICP estimations of normal subjects at increasing altitudes. The vODM was calibrated against actual ICP in 12 neurosurgical patients, most affected with acute hydrocephalus and monitored using ventriculostomy/pressure transducers. The operator was blinded to the transducer read-out. A clinical field test was then conducted on a variable data set of 42 volunteer trekkers and climbers scaling Mt. Everest, Nepal. Mean ICPs were estimated at several altitudes on the ascent both across and within subjects. Portable vODM measurements increased directly and linearly with ICP resulting in good predictability (r = 0.85). We also found that estimated ICP increases normally with altitude (10 ± 3 mm Hg; sea level to 20 ± 2 mm Hg; 6553 m) and that AMS symptoms did not correlate with raised ICP. vODM technology has potential to reliably estimate absolute ICP and is portable. Physiologic increases in ICP and mild-mod AMS are separate responses to high altitude, possibly reflecting swelling and vasoactive instability, respectively.

Psyllium

MedlinePlus

Psyllium, a bulk-forming laxative, is used to treat constipation. It absorbs liquid in the intestines, swells, and forms a bulky stool, which ... doctor if you have or have ever had diabetes mellitus, heart disease, high blood pressure, kidney disease, ...

Swelling of two-dimensional polymer rings by trapped particles.

PubMed

Haleva, E; Diamant, H

2006-09-01

The mean area of a two-dimensional Gaussian ring of N monomers is known to diverge when the ring is subject to a critical pressure differential, p c ~ N -1. In a recent publication (Eur. Phys. J. E 19, 461 (2006)) we have shown that for an inextensible freely jointed ring this divergence turns into a second-order transition from a crumpled state, where the mean area scales as [A]~N-1, to a smooth state with [A]~N(2). In the current work we extend these two models to the case where the swelling of the ring is caused by trapped ideal-gas particles. The Gaussian model is solved exactly, and the freely jointed one is treated using a Flory argument, mean-field theory, and Monte Carlo simulations. For a fixed number Q of trapped particles the criticality disappears in both models through an unusual mechanism, arising from the absence of an area constraint. In the Gaussian case the ring swells to such a mean area, [A]~ NQ, that the pressure exerted by the particles is at p c for any Q. In the freely jointed model the mean area is such that the particle pressure is always higher than p c, and [A] consequently follows a single scaling law, [A]~N(2) f (Q/N), for any Q. By contrast, when the particles are in contact with a reservoir of fixed chemical potential, the criticality is retained. Thus, the two ensembles are manifestly inequivalent in these systems.

Aquaporin-4 deletion in mice reduces encephalopathy and brain edema in experimental acute liver failure.

PubMed

Rama Rao, Kakulavarapu V; Verkman, A S; Curtis, Kevin M; Norenberg, Michael D

2014-03-01

Brain edema and associated astrocyte swelling leading to increased intracranial pressure are hallmarks of acute liver failure (ALF). Elevated blood and brain levels of ammonia have been implicated in the development of brain edema in ALF. Cultured astrocytes treated with ammonia have been shown to undergo cell swelling and such swelling was associated with an increase in the plasma membrane expression of aquaporin-4 (AQP4) protein. Further, silencing the AQP4 gene in cultured astrocytes was shown to prevent the ammonia-induced cell swelling. Here, we examined the evolution of brain edema in AQP4-null mice and their wild type counterparts (WT-mice) in different models of ALF induced by thioacetamide (TAA) or acetaminophen (APAP). Induction of ALF with TAA or APAP significantly increased brain water content in WT mice (by 1.6% ± 0.3 and 2.3 ± 0.4%, respectively). AQP4 protein was significantly increased in brain plasma membranes of WT mice with ALF induced by either TAA or APAP. In contrast to WT-mice, brain water content did not increase in AQP4-null mice. Additionally, AQP4-null mice treated with either TAA or APAP showed a remarkably lesser degree of neurological deficits as compared to WT mice; the latter displayed an inability to maintain proper gait, and demonstrated a markedly reduced exploratory behavior, with the mice remaining in one corner of the cage with its head tilted downwards. These results support a central role of AQP4 in the brain edema associated with ALF. Published by Elsevier Inc.

Aquaporin-4 Deletion in Mice Reduces Encephalopathy and Brain Edema in Experimental Acute Liver Failure

PubMed Central

Rama Rao, Kakulavarapu V.; Verkman, A. S.; Curtis, Kevin M.; Norenberg, Michael D.

2014-01-01

Brain edema and associated astrocyte swelling leading to increased intracranial pressure are hallmarks of acute liver failure (ALF). Elevated blood and brain levels of ammonia have been implicated in the development of brain edema in ALF. Cultured astrocytes treated with ammonia have been shown to undergo cell swelling and such swelling was associated with an increase in the plasma membrane expression of aquaporin-4 (AQP4) protein. Further, silencing the AQP4 gene in cultured astrocytes was shown to prevent the ammonia-induced cell swelling. Here, we examined the evolution of brain edema in AQP4-null mice and their wild type counterparts (WT-mice) in different models of ALF induced by thioacetamide (TAA) or acetaminophen (APAP). Induction of ALF with TAA or APAP significantly increased brain water content in WT mice (by 1.6 ± 0.3 and 2.3 ± 0.4 %, respectively). AQP4 protein was significantly increased in brain plasma membranes of WT mice with ALF induced by either TAA or APAP. In contrast to WT-mice, brain water content did not increase in AQP4-null mice. Additionally, AQP4-null mice treated with either TAA or APAP showed a remarkably lesser degree of neurological deficits as compared to WT mice; the latter displayed an inability to maintain proper gait, and demonstrated a markedly reduced exploratory behavior, with the mice remaining in one corner of the cage with its head tilted downwards. These results support a central role of AQP4 in the brain edema associated with ALF. PMID:24321433

Etude de l'effet du gonflement par les solvants sur les proprietes du caoutchouc butyle

NASA Astrophysics Data System (ADS)

Nohile, Cedrick

Polymers and in particular elastomers are widely used for personal protective equipment against chemical and biological hazards. Among them, butyl rubber is one of the most effective elastomers against chemicals. However, if this rubber has a very good resistance to a wide range of them, it is sensitive to non polar solvents. These solvents will easily swell the material and may dramatically affect its properties. This situation may involve a large risk for. butyl rubber protective equipment users. It is thus essential to improve the understanding of the effect of solvents on the properties of butyl rubber. The research that was carried out had two objectives: to identify the parameters controlling the resistance of butyl rubber to solvents and to study the effect of swelling on the properties of butyl rubber. The results show that the resistance of butyl rubber to solvents appears to be controlled by three main parameters: the chemical class of the solvent, its saturation vapor pressure and its molar volume. In addition, swelling affects butyl rubber mechanical properties in a permanent way. The effects can be attributed to the extraction of plasticizers by the solvent and to the degradation of the physico-chemical structure of the polymer network. This chemical degradation was linked to a phenomenon of differential swelling which seems to be controlled by the solvent flow inside the material. These results question some general beliefs within the field of protection against chemical risks. They also open new perspectives for the development of predictive tools relative to the behavior of butyl rubber in the presence of solvents

Effects of gas sorption-induced swelling/shrinkage on the cleat compressibility of coal under different bedding directions.

PubMed

Peng, Shoujian; Fang, Zhiming; Shen, Jian; Xu, Jiang; Wang, Geoff

2017-10-30

The cleat compressibility of coal is a key parameter that is extensively used in modeling the coal reservoir permeability for Coal Bed Methane (CBM) recovery. Cleat compressibility is often determined from the permeability measurement made at different confining pressures but with a constant pore pressure. Hence, this parameter ignores the sorption strain effects on the cleat compressibility. By using the transient pulse decay (TPD) technique, this study presents the results from a laboratory characterization program using coal core drilled from different bedding directions to estimate gas permeability and coal cleat compressibility under different pore pressures while maintaining effective stress constant. Cleat compressibility was determined from permeability and sorption strain measurements that are made at different pore pressures under an effective stress constant. Results show that the cleat compressibility of coal increases slightly with the increase of pore pressure. Moreover, the cleat compressibility of Sample P (representing the face cleats in coal) is larger than that of Sample C (representing the butt cleats in coal). This result suggests that cleat compressibility should not be regarded as constant in the modeling of the CBM recovery. Furthermore, the compressibility of face cleats is considerably sensitive to the sorption-induced swelling/shrinkage and offers significant effects on the coal permeability.

Recrystallization characteristics of high hydrostatic pressure gelatinized normal and waxy corn starch.

PubMed

Li, Wenhao; Tian, Xiaoling; Wang, Peng; Saleh, Ahmed S M; Luo, Qingui; Zheng, Jianmei; Ouyang, Shaohui; Zhang, Guoquan

2016-02-01

High hydrostatic pressure (HHP) can lead to starch gelatinization at room temperature, while the retrogradation mechanism of HHP gelatinized starch is not well known. HHP gelatinized normal and waxy corn starches were stored at room temperature for 192 h in order to investigate the retrogradation characteristics. The scanning electron microscopy (SEM), polarised light microscopy and differential scanning calorimetric (DSC) analysis showed that the pressurization of normal and waxy corn starch suspensions with concentration of 30% (w/v) at 600 MPa for 15 min resulted in a complete gelatinization. In addition, the pressure-gelatinized normal and waxy corn starch gels were stored and subjected to X-ray diffraction (XRD) analysis, resistant starch content determination, swelling power and pasting behavior. The retrograded normal maize and waxy maize starch showed a substantial loss of A-type crystallinity. Both pressure-gelatinized normal and waxy corn starches showed an increase in resistant starch content and relative crystallinity degree with the increase of storage time. In addition, restricted starch swelling power and lower pasting viscosities were observed for these two retrograded starches. The amylose molecule within starch granules has been regarded as the main factor to affect the structural and physicochemical properties during the retrogradation process of HHP-gelatinized starch granules. Copyright © 2015 Elsevier B.V. All rights reserved.

Growth regulation in tip-growing cells that develop on the epidermis.

PubMed

Honkanen, Suvi; Dolan, Liam

2016-12-01

Plants develop tip-growing extensions-root hairs and rhizoids-that initiate as swellings on the outer surface of individual epidermal cells. A conserved genetic mechanism controls the earliest stages in the initiation of these swellings. The same mechanism controls the formation of multicellular structures that develop from swellings on epidermal cells in early diverging land plants. Details of the molecular events that regulate the positioning of the swellings involve sterols and phosphatidylinositol phosphates. The final length of root hairs is determined by the intensity of a pulse of transcription factor synthesis. Genes encoding similar transcription factors control root hair development in cereals and are potential targets for crop improvement. Copyright © 2016. Published by Elsevier Ltd.

Na-K-Cl Cotransporter-1 in the Mechanism of Ammonia-induced Astrocyte Swelling*

PubMed Central

Jayakumar, Arumugam R.; Liu, Mingli; Moriyama, Mitsuaki; Ramakrishnan, Ramugounder; Forbush, Bliss; Reddy, Pichili V. B.; Norenberg, Michael D.

2008-01-01

Brain edema and the consequent increase in intracranial pressure and brain herniation are major complications of acute liver failure (fulminant hepatic failure) and a major cause of death in this condition. Ammonia has been strongly implicated as an important factor, and astrocyte swelling appears to be primarily responsible for the edema. Ammonia is known to cause cell swelling in cultured astrocytes, although the means by which this occurs has not been fully elucidated. A disturbance in one or more of these systems may result in loss of ion homeostasis and cell swelling. In particular, activation of the Na-K-Cl cotransporter (NKCC1) has been shown to be involved in cell swelling in several neurological disorders. We therefore examined the effect of ammonia on NKCC activity and its potential role in the swelling of astrocytes. Cultured astrocytes were exposed to ammonia (NH4Cl; 5 mm), and NKCC activity was measured. Ammonia increased NKCC activity at 24 h. Inhibition of this activity by bumetanide diminished ammonia-induced astrocyte swelling. Ammonia also increased total as well as phosphorylated NKCC1. Treatment with cyclohexamide, a potent inhibitor of protein synthesis, diminished NKCC1 protein expression and NKCC activity. Since ammonia is known to induce oxidative/nitrosative stress, and antioxidants and nitric-oxide synthase inhibition diminish astrocyte swelling, we also examined whether ammonia caused oxidation and/or nitration of NKCC1. Cultures exposed to ammonia increased the state of oxidation and nitration of NKCC1, whereas the antioxidants N-nitro-l-arginine methyl ester and uric acid all significantly diminished NKCC activity. These agents also reduced phosphorylated NKCC1 expression. These results suggest that activation of NKCC1 is an important factor in the mediation of astrocyte swelling by ammonia and that such activation appears to be mediated by NKCC1 abundance as well as by its oxidation/nitration and phosphorylation. PMID:18849345

The application of the high-speed photography in the experiments of boiling liquid expanding vapor explosions

NASA Astrophysics Data System (ADS)

Chen, Sining; Sun, Jinhua; Chen, Dongliang

2007-01-01

The liquefied-petroleum gas tank in some failure situations may release its contents, and then a series of hazards with different degrees of severity may occur. The most dangerous accident is the boiling liquid expanding vapor explosion (BLEVE). In this paper, a small-scale experiment was established to experimentally investigate the possible processes that could lead to a BLEVE. As there is some danger in using LPG in the experiments, water was used as the test fluid. The change of pressure and temperature was measured during the experiment. The ejection of the vapor and the sequent two-phase flow were recorded by a high-speed video camera. It was observed that two pressure peaks result after the pressure is released. The vapor was first ejected at a high speed; there was a sudden pressure drop which made the liquid superheated. The superheated liquid then boiled violently causing the liquid contents to swell, and also, the vapor pressure in the tank increased rapidly. The second pressure peak was possibly due to the swell of this two-phase flow which was likely to violently impact the wall of the tank with high speed. The whole evolution of the two-phase flow was recorded through photos captured by the high-speed video camera, and the "two step" BLEVE process was confirmed.

Interface fluid syndrome in human eye bank corneas after LASIK: causes and pathogenesis.

PubMed

Dawson, Daniel G; Schmack, Ingo; Holley, Glenn P; Waring, George O; Grossniklaus, Hans E; Edelhauser, Henry F

2007-10-01

To evaluate the effects of corneal edema on human donor corneas that had previous LASIK using a laboratory model with histologic and ultrastructural correlations. Experimental study. Thirty human eye bank corneas from 15 donors (mean age +/- standard deviation, 49.9+/-8.9 years) who had had previous LASIK surgery (2-8 years before death). The corneas were mounted in an artificial anterior chamber and the corneal endothelium was perfused for up to 5.0 hours with 0.9% saline solution (endothelial cell damage group) or BSS Plus at a pressure of 15 mmHg (control group), or BSS Plus at a pressure of 55 mmHg (high-pressure group). The corneas were evaluated by confocal and specular microscopy before, during, and at the end of the experimental period. Subsequently, the specimens were evaluated by light and electron microscopy. Corneal thickness, reflectivity, histology, and ultrastructure. Endothelial cell damage resulted in an increased (141.5+/-38.8 microm) total corneal thickness relative to controls (52.3+/-33.7 microm), whereas high pressure resulted in a decreased thickness (24.8+/-14.1 microm) relative to controls. This ultimately was due to swelling of the LASIK interface in both groups and swelling of the residual stromal bed (RSB) in the endothelial cell damage group or compression of the RSB and, possibly, the flap in the high-pressure group. A significant increase in corneal reflectivity at the LASIK interface occurred in both groups, primarily due to varying degrees of fluid accumulation and associated hydropic keratocyte degeneration, as well as increased corneal reflectivity in the RSB only in the endothelial cell damage group. After LASIK surgery, edematous corneas preferentially hydrate and swell in the paracentral and central interface wound, commonly resulting in a hazy corneal appearance primarily due to keratocyte hydropic degeneration. More severe corneal edema is characterized by the formation of an optically empty space corresponding to an interface fluid pocket. The spectrum of interface fluid syndrome can be described in 3 stages.

Lupus nephritis

MedlinePlus

... time, kidney failure can result. Symptoms Symptoms of lupus nephritis include: Blood in the urine Foamy appearance to urine Swelling (edema) of any area of the body High blood pressure Exams and Tests The health care provider will perform a physical ...

Shaken baby symptoms (image)

MedlinePlus

... is a severe form of head injury caused by the baby's brain rebounding inside of the baby's skull when shaken. In this injury there is bruising of the brain, swelling, pressure, and bleeding (intracerebral hemorrhage). This can easily lead ...

Ambient seismic wave field

PubMed Central

NISHIDA, Kiwamu

2017-01-01

The ambient seismic wave field, also known as ambient noise, is excited by oceanic gravity waves primarily. This can be categorized as seismic hum (1–20 mHz), primary microseisms (0.02–0.1 Hz), and secondary microseisms (0.1–1 Hz). Below 20 mHz, pressure fluctuations of ocean infragravity waves reach the abyssal floor. Topographic coupling between seismic waves and ocean infragravity waves at the abyssal floor can explain the observed shear traction sources. Below 5 mHz, atmospheric disturbances may also contribute to this excitation. Excitation of primary microseisms can be attributed to topographic coupling between ocean swell and seismic waves on subtle undulation of continental shelves. Excitation of secondary microseisms can be attributed to non-linear forcing by standing ocean swell at the sea surface in both pelagic and coastal regions. Recent developments in source location based on body-wave microseisms enable us to estimate forcing quantitatively. For a comprehensive understanding, we must consider the solid Earth, the ocean, and the atmosphere as a coupled system. PMID:28769015

Laser swelling of soft biological tissue by IR pulses

NASA Astrophysics Data System (ADS)

Malyshev, A.; Bityurin, N.

The temporal dynamics of biological tissue swelling under the effect of mid-IR laser radiation is considered theoretically following the experimental investigation published earlier. The probable mechanism of laser swelling is suggested. This mechanism consists of deformation of tissue protein base by vapor pressure, which appears due to evaporation of tissue water. The formation and relaxation of a hump on the surface was determined by both mechanical properties (elastic, plastic) and porosity of material providing water vapor transfer within tissue. It is found that these mechanisms can lead to the formation of both transient and stationary hump structures on the surface. To describe the hump relaxation, we consider a new, evaporation-condensation, mechanism of heat transfer within the region of biotissue with microchannels. This mechanism allows us to explain the value of relaxation time of the hump measured in experiment.

Geological Disposal of Nuclear Waste: Investigating the Thermo-Hygro-Mechanical-Chemical (THMC) Coupled Processes at the Waste Canister- Bentonite Barrier Interface

NASA Astrophysics Data System (ADS)

Davies, C. W.; Davie, D. C.; Charles, D. A.

2015-12-01

Geological disposal of nuclear waste is being increasingly considered to deal with the growing volume of waste resulting from the nuclear legacy of numerous nations. Within the UK there is 650,000 cubic meters of waste safely stored and managed in near-surface interim facilities but with no conclusive permanent disposal route. A Geological Disposal Facility with incorporated Engineered Barrier Systems are currently being considered as a permanent waste management solution (Fig.1). This research focuses on the EBS bentonite buffer/waste canister interface, and experimentally replicates key environmental phases that would occur after canister emplacement. This progresses understanding of the temporal evolution of the EBS and the associated impact on its engineering, mineralogical and physicochemical state and considers any consequences for the EBS safety functions of containment and isolation. Correlation of engineering properties to the physicochemical state is the focus of this research. Changes to geotechnical properties such as Atterberg limits, swelling pressure and swelling kinetics are measured after laboratory exposure to THMC variables from interface and batch experiments. Factors affecting the barrier, post closure, include corrosion product interaction, precipitation of silica, near-field chemical environment, groundwater salinity and temperature. Results show that increasing groundwater salinity has a direct impact on the buffer, reducing swelling capacity and plasticity index by up to 80%. Similarly, thermal loading reduces swelling capacity by 23% and plasticity index by 5%. Bentonite/steel interaction studies show corrosion precipitates diffusing into compacted bentonite up to 3mm from the interface over a 4 month exposure (increasing with temperature), with reduction in swelling capacity in the affected zone, probably due to the development of poorly crystalline iron oxides. These results indicate that groundwater conditions, temperature and corrosion may affect the engineering performance of the bentonite buffer such that any interfaces between bentonite blocks that may be present immediately following buffer emplacement may persist in the longer term.

Clustering of Synoptic Pattern over the Korean Peninsula from Meteorological Models

NASA Astrophysics Data System (ADS)

Kim, Jinah; Heo, Kiyoung; Choi, Jungwoon; Jung, Sanghoon

2017-04-01

Numerical modeling data on meteorological and ocean science is one of example of big geographic data sources. The properties of the data including the volume, variety, and dynamic aspects pose new challenges for geographic visualization, and visual geoanalytics using big data analysis using machine learning method. A combination of algorithmic and visual approaches that make sense of large volumes of various types of spatiotemporal data are required to gain knowledge about complex phenomena. In the East coast of Korea, it is suffering from property damages and human causalities due to abnormal high waves (swell-like high-height waves). It is known to be caused by local meteorological conditions on the East Sea of Korean Peninsula in previous research and they proposed three kinds of pressure patterns that generate abnormal high waves. However, they cannot describe all kinds of pressure patterns that generate abnormal high waves. In our study, we propose unsupervised machine learning method for pattern clustering and applied it to classify a pattern which has occurred abnormal high waves using numerical meteorological model's reanalysis data from 2000 to 2015 and past historical records of accidents by abnormal high waves. About 25,000 patterns of total spatial distribution of sea surface pressure are clustered into 30 patterns and they are classified into seasonal sea level pressure patterns based on meteorological characteristics of Korean peninsula. Moreover, in order to determine the representative patterns which occurs abnormal high waves, we classified it again using historical accidents cases among the winter season pressure patterns. In this work, we clustered synoptic pattern over the Korean Peninsula in meteorological modeling reanalysis data and we could understand a seasonal variation through identifying the occurrence of clustered synoptic pattern. For the future work, we have to identify the relationship of wave modeling data for better understanding of abnormal high waves and we will develop pattern decision system to predict abnormal high waves in advances. This research was a part of the project titled "Development of Korea Operational Oceanographic System (KOOS), Phase 2" and "Investigation of Large Swell Waves and Rip currents and Development of The Disaster Response System," funded by the Ministry of Oceans & Fisheries Korea (Grant PM59691 and PM59240).

TSPO activation modulates the effects of high pressure in a rat ex vivo glaucoma model

PubMed Central

Ishikawa, Makoto; Yoshitomi, Takeshi; Covey, Douglas F.; Zorumski, Charles F.; Izumi, Yukitoshi

2017-01-01

We previously reported that elevated pressure induces axonal swelling and facilitates the synthesis of the neurosteroid, allopregnanolone (AlloP), in the ex vivo rat retina. Exogenously applied AlloP attenuates the axonal swelling, suggesting that the neurosteroid plays a neuroprotective role against glaucomatous pressure-induced injuries, although mechanisms underlying neurosteroidogenesis have not been clarified. The aim of this study was to determine whether AlloP synthesis involves activation of translocator protein 18 kD (TSPO) and whether TSPO modulates pressure-induced retinal injury. Ex vivo rat retinas were exposed to various pressures (10, 35, or 75 mmHg) for 24 hours. Expression of TSPO, 5α-reductase (5aRD), and AlloP was examined by quantitative real-time RT-PCR, ELISA, immunohistochemistry, and LC-MS/MS. We also examined the effects of TSPO ligands on AlloP synthesis and retinal damage. In this acute model, quantitative real-time RT-PCR and ELISA analyses revealed that elevated pressure facilitated TSPO expression. Similarly, these methods also detected enhanced 5aRD (mostly type II), which was observed in retinal ganglion cells (RGC) and the inner nuclear layer (INL). Atriol, a TSPO antagonist, suppressed pressure mediated AlloP synthesis and induced more severe histological changes in the inner retina when combined with elevated pressure. PK11195, a TSPO ligand that facilitates AlloP synthesis by itself, remarkably diminished pressure-mediated retinal degeneration. These results suggest that AlloP synthesis is induced by sequential activation of TSPO and 5aRD in an ex vivo glaucoma model, and that TSPO agonists may serve as potential therapeutic agents for the prevention of pressure-induced retinal damage. PMID:27596950

The central tower of the cathedral of Schleswig - New investigations to understand the alcali-silica reaction of historical mortars

NASA Astrophysics Data System (ADS)

Wedekind, Wanja; Protz, Andreas

2016-04-01

The damaging alcali-silica reaction leads to crack-formation and structural destruction at noumerous, constructed with cement mortar, buildings worldwide. The ASR-reaction causes the expansion of altered aggregates by the formation of a swelling gel. This gel consists of calcium silicate hydrate (C-S-H) that increases in volume with water, which exerts an expansive pressure inside the material. The cathedral of Schleswig is one of the oldest in northern Germany. The first church was built in 985-965. The Romanesque building part was erected around 1180 and the Gothic nave at the end of the 13th century. The central tower was constructed between 1888 and 1894 with brick and cement mortar. With 112 meters, the tower is the second-largest church spire of the country of Schleswig-Holstein in northern Germany. Due to the formation of cracks and damages from 1953 to 1956 first restoration works took place. Further developments of cracks are making restoration necessary again today. For developing a suitable conservation strategy, different investigations were done. The investigation included the determination of the pore space properties, the hygric and thermal dilatation and mercury porosimetry measurements. Furthermore, the application of cathodoluminescence microscopy may give information about the alteration process and microstructures present and reveal the differences between unaltered and altered mortars. An obvious relation between the porosity and the swelling intensity could be detected. Furthermore it becomes apparent, that a clear zonation of the mortar took place. The mortar near the surface is denser with a lower porosity and has a significantly lower swelling or dilatation.

Prefabricated Cervical Skin Flaps for Hemi-Facial Resurfacing: Elucidating the Natural History of Postoperative Edema Using Indocyanine Green.

PubMed

Li, Ke; Min, Peiru; Sadigh, Parviz; Grassetti, Luca; Lazzeri, Davide; Torresetti, Matteo; Marsili, Riccardo; Feng, Shaoqing; Liu, Ningfei; Zhang, Yi Xin

2018-02-01

The increases in capillary wall permeability and capillary hydrostatic pressure are considered to be the causes for the acute swelling seen in flaps; however, disruption of the circulating flap lymphatics could be another contributory factor. In this study we monitor the development of flap edema in a series of 18 prefabricated flaps and aim to delineate the natural history of this phenomenon by use of lymphography. Postoperative swelling was monitored in a series of 18 pre-expanded prefabricated cervical skin flaps used for hemi-facial burns-scar resurfacing. Time to spontaneous resolution, presence or absence of venous congestion, and clinical outcome were recorded. In two cases, indocyanine-green (ICG) lymphography was used to monitor the dermal backflow pattern until swelling had completely resolved. Average moving velocity of ICG after injection as well as flap thickness was also recorded over the follow-up period. The average moving velocity of ICG in the flap lymphatics improved from 0.48 cm/min to 1.5 cm/min in the first 12 days after flap transfer. The dermal backflow pattern was stardust in the first 12 days, indicating moderate lymphedema, transforming to splash from week three, and a robust collecting lymphatic vessel occurring from the fifth month, indicating mild lymphedema and lymphatic channel recovery, respectively. Transient swelling was observed in all prefabricated flaps in our series. We postulate that this is mostly secondary to lymphatic disruption that subsides as lymphangiogenesis takes place. ICG lymphography is an inexpensive, safe, and easy-to-use imaging technology that could be used in the monitoring of postoperative lymphedema seen in prefabricated flaps.

Preparation of SMART wound dressings based on colloidal microgels and textile fibres

NASA Astrophysics Data System (ADS)

Cornelius, Victoria J.; Majcen, Natasa; Snowden, Martin J.; Mitchell, John C.; Voncina, Bojana

2007-01-01

Wound dressings and other types of wound healing technologies are experiencing fast-paced development and rapid growth. As the population ages, demand will continue to rise for advanced dressings used to treat chronic wounds, such as pressure ulcers, venous stasis ulcers, and diabetic ulcers. Moist wound dressings, which facilitate natural wound healing in a cost-effective manner, will be increasingly important. In commercially available hydrogel / gauze wound dressings the gel swells to adsorb wound excreta and provide an efficient non adhesive particle barrier. An alternative to hydrogels are microgels. Essentially discrete colloidal gel particles, as a result of their very high surface area to volume ratio compared to bulk gels, they have a much faster response to external stimuli such as temperature or pH. In response to either an increase or decrease in solvent quality these porous networks shrink and swell reversibly. When swollen the interstitial regions within the polymer matrix are available for further chemistry; such as the incorporation of small molecules. The reversible shrinking and swelling as a function of external stimuli provides a novel drug release system. As the environmental conditions of a wound change over its lifetime, tending to increase in pH if there is an infection combining these discrete polymeric particles with a substrate such as cotton, results in a smart wound dressing.

The Effect of the South Asia Monsoon on the Wind Sea and Swell Patterns in the Arabian Sea

NASA Astrophysics Data System (ADS)

Semedo, Alvaro

2015-04-01

Ocean surface gravity waves have a considerable impact on coastal and offshore infrastructures, and are determinant on ship design and routing. But waves also play an important role on the coastal dynamics and beach erosion, and modulate the exchanges of momentum, and mass and other scalars between the atmosphere and the ocean. A constant quantitative and qualitative knowledge of the wave patterns is therefore needed. There are two types of waves at the ocean surface: wind-sea and swell. Wind-sea waves are growing waves under the direct influence of local winds; as these waves propagate away from their generation area, or when their phase speed overcomes the local wind speed, they are called swell. Swell waves can propagate thousands of kilometers across entire ocean basins. The qualitative analysis of ocean surface waves has been the focus of several recent studies, from the wave climate to the air-sea interaction community. The reason for this interest lies mostly in the fact that waves have an impact on the lower atmosphere, and that the air-sea coupling is different depending on the wave regime. Waves modulate the exchange of momentum, heat, and mass across the air-sea interface, and this modulation is different and dependent on the prevalence of one type of waves: wind sea or swell. For fully developed seas the coupling between the ocean-surface and the overlaying atmosphere can be seen as quasi-perfect, in a sense that the momentum transfer and energy dissipation at the ocean surface are in equilibrium. This can only occur in special areas of the Ocean, either in marginal seas, with limited fetch, or in Open Ocean, in areas with strong and persistent wind speed with little or no variation in direction. One of these areas is the Arabian Sea, along the coasts of Somalia, Yemen and Oman. The wind climate in the Arabian sea is under the direct influence of the South Asia monsoon, where the wind blows steady from the northeast during the boreal winter, and reverses direction to blow also steady but stronger from the southwest during the boreal summer months. During the summer monsoon the wind pattern in the north Arabian Sea is rather intricate, with a large scale synoptic forcing with a high pressure cell over the ocean and a thermal low pressure system in-land, but also with at least two low-level wind jets, the Finlater (or Somali) jet, and the Oman coastal jet. This wind pattern leads to a particular wave pattern and seasonal variability. The monsoon wind pattern has a direct influence in the wave climate in that area, The particular wind-sea and swell climates of the Arabian Sea are presented. The study is based on the ERA-Interim wave reanalysis from the European Centre for Medium-Range Weather Forecasts.

A three-scale model for ionic solute transport in swelling clays incorporating ion-ion correlation effects

NASA Astrophysics Data System (ADS)

Le, Tien Dung; Moyne, Christian; Murad, Marcio A.

2015-01-01

A new three-scale model is proposed to describe the movement of ionic species of different valences in swelling clays characterized by three separate length scales (nano, micro, and macro) and two levels of porosity (nano- and micropores). At the finest (nano) scale the medium is treated as charged clay particles saturated by aqueous electrolyte solution containing monovalent and divalent ions forming the electrical double layer. A new constitutive law is constructed for the disjoining pressure based on the numerical resolution of non-local problem at the nanoscale which, in contrast to the Poisson-Boltzmann theory for point charge ions, is capable of capturing the short-range interactions between the ions due to their finite size. At the intermediate scale (microscale), the two-phase homogenized particle/electrolyte solution system is represented by swollen clay clusters (or aggregates) with the nanoscale disjoining pressure incorporated in a modified form of Terzaghi's effective principle. At the macroscale, the electro-chemical-mechanical couplings within clay clusters is homogenized with the ion transport in the bulk fluid lying in the micro pores. The resultant macroscopic picture is governed by a three-scale model wherein ion transport takes place in the bulk solution strongly coupled with the mechanics of the clay clusters which play the role of sources/sinks of mass to the bulk fluid associated with ion adsorption/desorption in the electrical double layer at the nanoscale. Within the context of the quasi-steady version of the multiscale model, wherein the electrolyte solution in the nanopores is assumed at instantaneous thermodynamic equilibrium with the bulk fluid in the micropores, we build-up numerically the ion-adsorption isotherms along with the constitutive law of the retardation coefficients of monovalent and divalent ions. In addition, the constitutive law for the macroscopic swelling pressure is reconstructed numerically showing patterns of attractive forces between particles for bivalent ions for particular ranges of bulk concentrations. The three-scale model is applied to numerically simulate ion diffusion in a compacted clay liner underneath a sanitary landfill. Owing to the distinct constitutive behavior of the swelling pressure and partition coefficient for each ionic species, different compaction regimes and diffusion/adsorption patterns, with totally different characteristic time scales, are observed for sodium and calcium migration in the clay liner.

Effect of water on methane adsorption on the kaolinite (0 0 1) surface based on molecular simulations

NASA Astrophysics Data System (ADS)

Zhang, Bin; Kang, Jianting; Kang, Tianhe

2018-05-01

CH4 adsorption isotherms of kaolinite with moisture contents ranging from 0 to 5 wt% water, the effects of water on maximum adsorption capacity, kaolinite swelling, and radial distribution function were modelled by the implementing combined Monte Carlo (MC) and molecular dynamics (MD) simulations at 293.15 K (20 °C) and a pressure range of 1-20 MPa. The simulation results showed that the absolute adsorption of CH4 on both dry and moist kaolinite followed a Langmuir isotherm within the simulated pressure range, and both the adsorption capacity and the rate of CH4 adsorption decreased with the water content increases. The adsorption isosteric heats of CH4 on kaolinite decreased linearly with increasing water content, indicating that at higher water contents, the interaction energy between the CH4 and kaolinite was weaker. The interaction between kaolinite and water dominates and was the main contributing factor to kaolinite clay swelling. Water molecules were preferentially adsorbed onto oxygen and hydrogen atoms in kaolinite, while methane showed a tendency to be adsorbed only onto oxygen. The simulation results of our study provide the quantitative analysis of effect of water on CH4 adsorption capacity, adsorption rate, and interaction energy from a microscopic perspective. We hope that our study will contribute to the development of strategies for the further exploration of coal bed methane and shale gas.

Effect of Casting Material on the Cast Pressure After Sequential Cast Splitting.

PubMed

Roberts, Aaron; Shaw, K Aaron; Boomsma, Shawn E; Cameron, Craig D

2017-01-01

Circumferential casting is a vital component of nonoperative fracture management. These casts are commonly valved to release pressure and decrease the risk of complications from swelling. However, little information exists regarding the effect of different casting supplies on the pressure within the cast. Seventy-five long-arm casts were performed on human volunteers, divided between 5 experimental groups with 15 casts in each groups. Testing groups consisted of 2 groups with a plaster short-arm cast overwrapped with fiberglass to a long arm with either cotton or synthetic cast padding. The 3 remaining groups included fiberglass long-arm casts with cotton, synthetic, or waterproof cast padding. A pediatric blood pressure cuff bladder was placed within the cast and inflated to 100 mm Hg. After inflation, the cast was sequentially released with pressure reading preformed after each stage. Order of release consisted of cast bivalve, cast padding release, and cotton stockinet release. After release, the cast was overwrapped with a loose elastic bandage. Difference in pressure readings were compared based upon the cast material. Pressures within the cast were found to decrease with sequential release of cast. The cast type had no effect of change in pressure. Post hoc testing demonstrated that the type of cast padding significantly affected the cast pressures with waterproof padding demonstrating the highest pressure readings at all time-points in the study, followed by synthetic padding. Cotton padding had the lowest pressure readings at all time-points. Type of cast padding significantly influences the amount of pressure within a long-arm cast, even after bivalving the cast and cutting the cast padding. Cotton cast padding allows for the greatest change in pressure. Cotton padding demonstrates the greatest change in pressure within a long-arm cast after undergoing bivalve. Synthetic and waterproof cast padding should not be used in the setting of an acute fracture to accommodate swelling.

On sorption and swelling of CO 2 in clays

DOE PAGES

Busch, A.; Bertier, P.; Gensterblum, Y.; ...

2016-03-23

One well-studied technology is the geological storage of carbon dioxide (CO 2), and a number of demonstration projects around the world have proven its feasibility and challenges. Storage conformance and seal integrity are among the most important aspects, as they determine risk of leakage as well as limits for storage capacity and injectivity. By providing evidence for safe storage is critical for improving public acceptance. Most caprocks are composed of clays as dominant mineral type which can typically be illite, kaolinite, chlorite or smectite. A number of recent studies addressed the interaction between CO 2 and these different clays andmore » it was shown that clay minerals adsorb considerable quantities of CO 2. For smectite this uptake can lead to volumetric expansion followed by the generation of swelling pressures. On the one hand CO 2 adsorption traps CO 2, on the other hand swelling pressures can potentially change local stress regimes and in unfavourable situations shear-type failure is assumed to occur. Moreover, for storage in a reservoir having high clay contents the CO 2 uptake can add to storage capacity which is widely underestimated so far. Smectite-rich seals in direct contact with a dry CO 2 plume at the interface to the reservoir might dehydrate leading to dehydration cracks. Such dehydration cracks can provide pathways for CO 2 ingress and further accelerate dewatering and penetration of the seal by supercritical CO 2. At the same time, swelling may also lead to the closure of fractures or the reduction of fracture apertures, thereby improving seal integrity. Finally, the goal of this communication is to theoretically evaluate and discuss these scenarios in greater detail in terms of phenomenological mechanisms, but also in terms of potential risks or benefits for carbon storage.« less

Snoring-Induced Vibratory Angioedema

PubMed Central

Kalathoor, Ipe

2015-01-01

Patient: Female, 70 Final Diagnosis: Snoring induced vibratory angioedema Symptoms: Swelling of tongue • roof of mouth and throat • multiple episodes at night Medication: — Clinical Procedure: Continuous positive airway pressure therapy Specialty: Allergology Objective: Rare disease Background: Vibratory angioedema (VA) is a rare physical urticaria, with symptoms of itching and swelling of the skin or mucosa when it is exposed to vibration. Avoidance of vibration is the best way to manage this condition. This case report will assist physicians to diagnose this rare condition. Here, a previously unpublished potential successful treatment modality is being presented, with good symptom control, along with some photographs taken during an acute attack. A literature review points towards potential undiagnosed cases. Case Report: A 70-year-old woman had multiple emergency department visits for tongue and throat swelling over 3 years. The episodes always happened at night. Detailed history elicited some episodes of itching and swelling of hands when driving as well as significant snoring while sleeping. Physical examination was unremarkable except for morbid obesity. Complement factor 4 and C1esterase inhibitor level were within normal limits. A tentative diagnosis of angioedema induced by oropharyngeal vibration from snoring was made. A sleep study confirmed sleep apnea with severe snoring. After CPAP (continuous positive airway pressure) treatment, she had successful symptom control. Conclusions: Snoring-induced VA is very likely an under-diagnosed condition in the community. The typical history is the key to the diagnosis. This condition could be confirmed by vibration test or by the resolution of symptoms with elimination of vibration. Effective symptom control is possible by avoidance of oropharyngeal vibration from snoring with the administration of CPAP therapy, making it a potential novel indication for this condition. PMID:26437464

Wicking Tests for Unidirectional Fabrics: Measurements of Capillary Parameters to Evaluate Capillary Pressure in Liquid Composite Molding Processes.

PubMed

Pucci, Monica Francesca; Liotier, Pierre-Jacques; Drapier, Sylvain

2017-01-27

During impregnation of a fibrous reinforcement in liquid composite molding (LCM) processes, capillary effects have to be understood in order to identify their influence on void formation in composite parts. Wicking in a fibrous medium described by the Washburn equation was considered equivalent to a flow under the effect of capillary pressure according to the Darcy law. Experimental tests for the characterization of wicking were conducted with both carbon and flax fiber reinforcement. Quasi-unidirectional fabrics were then tested by means of a tensiometer to determine the morphological and wetting parameters along the fiber direction. The procedure was shown to be promising when the morphology of the fabric is unchanged during capillary wicking. In the case of carbon fabrics, the capillary pressure can be calculated. Flax fibers are sensitive to moisture sorption and swell in water. This phenomenon has to be taken into account to assess the wetting parameters. In order to make fibers less sensitive to water sorption, a thermal treatment was carried out on flax reinforcements. This treatment enhances fiber morphological stability and prevents swelling in water. It was shown that treated fabrics have a linear wicking trend similar to those found in carbon fabrics, allowing for the determination of capillary pressure.

Laboratory correlation of soil swell potential : final report.

DOT National Transportation Integrated Search

1979-03-01

The objective of the study was to determine if a correlation exists between the Potential Volume Change Test and the Potential Vertical Rise Test as compared to the Third Cycle Expansion Pressure Test. In order to accomplish this objective, samples o...

A procyanidin type A trimer from cinnamon extract attenuates glial cell swelling and the reduction in glutamate uptake following ischemia-like injury in vitro.

PubMed

Panickar, K S; Polansky, M M; Graves, D J; Urban, J F; Anderson, R A

2012-01-27

Dietary polyphenols exert neuroprotective effects in ischemic injury. The protective effects of a procyanidin type A trimer (trimer 1) isolated from a water soluble cinnamon extract (CE) were investigated on key features of ischemic injury, including cell swelling, increased free radical production, increased intracellular calcium ([Ca(2+)](i)), mitochondrial dysfunction, and the reduction in glutamate uptake. Astrocyte (glial) swelling is a major component of cytotoxic brain edema in ischemia and, along with vasogenic edema, may contribute to increased intracranial pressure, brain herniation, and additional ischemic injuries. C6 glial cultures were exposed to oxygen-glucose deprivation (OGD) for 5 h, and cell swelling was determined at 90 min after the end of OGD. OGD-induced increases in glial swelling were significantly blocked by trimer 1, but not by the major nonpolyphenol fractions of CE including cinnamaldehyde and coumarin. Increased free radical production, a contributing factor in cell swelling following ischemic injury, was also significantly reduced by trimer 1. Mitochondrial dysfunction, another key feature of ischemic injury, is hypothesized to contribute to glial swelling. Depolarization of the inner mitochondrial membrane potential (ΔΨ(m)) was assessed using a fluorescent dye (tetramethylrhodamine ethyl ester [TMRE]), and was significantly attenuated by trimer 1 as was OGD-induced increased [Ca(2+)](i). Taken together with our previous observation that blockers of [Ca(2+)](i) reduce cell swelling, our results indicate that trimer 1 may attenuate cell swelling by regulating [Ca(2+)](i). Trimer 1 also significantly attenuated the OGD-induced decrease in glutamate uptake. In addition, cyclosporin A, a blocker of the mitochondrial permeability pore (mPT), but not FK506 (that does not block the mPT), reduced the OGD-induced decline in glutamate uptake indicating a role of the mPT in such effects. Thus, the effects of trimer 1 in attenuating the reduction in glutamate uptake are likely mediated through their action on the mitochondria. Published by Elsevier Ltd on behalf of IBRO.

Simulating the swelling and deformation behaviour in soft tissues using a convective thermal analogy

PubMed Central

Wu, John Z; Herzog, Walter

2002-01-01

Background It is generally accepted that cartilage adaptation and degeneration are mechanically mediated. Investigating the swelling behaviour of cartilage is important because the stress and strain state of cartilage is associated with the swelling and deformation behaviour. It is well accepted that the swelling of soft tissues is associated with mechanical, chemical, and electrical events. Method The purpose of the present study was to implement the triphasic theory into a commercial finite element tool (ABAQUS) to solve practical problems in cartilage mechanics. Because of the mathematical identity between thermal and mass diffusion processes, the triphasic model was transferred into a convective thermal diffusion process in the commercial finite element software. The problem was solved using an iterative procedure. Results The proposed approach was validated using the one-dimensional numerical solutions and the experimental results of confined compression of articular cartilage described in the literature. The time-history of the force response of a cartilage specimen in confined compression, which was subjected to swelling caused by a sudden change of saline concentration, was predicted using the proposed approach and compared with the published experimental data. Conclusion The advantage of the proposed thermal analogy technique over previous studies is that it accounts for the convective diffusion of ion concentrations and the Donnan osmotic pressure in the interstitial fluid. PMID:12685940

Effective diffusion coefficients of gas mixture in heavy oil under constant-pressure conditions

NASA Astrophysics Data System (ADS)

Li, Huazhou Andy; Sun, Huijuan; Yang, Daoyong

2017-05-01

We develop a method to determine the effective diffusion coefficient for each individual component of a gas mixture in a non-volatile liquid (e.g., heavy oil) at high pressures with compositional analysis. Theoretically, a multi-component one-way diffusion model is coupled with the volume-translated Peng-Robinson equation of state to quantify the mass transfer between gas and liquid (e.g., heavy oil). Experimentally, the diffusion tests have been conducted with a PVT setup for one pure CO2-heavy oil system and one C3H8-CO2-heavy oil system under constant temperature and pressure, respectively. Both the gas-phase volume and liquid-phase swelling effect are simultaneously recorded during the measurement. As for the C3H8-CO2-heavy oil system, the gas chromatography method is employed to measure compositions of the gas phase at the beginning and end of the diffusion measurement, respectively. The effective diffusion coefficients are then determined by minimizing the discrepancy between the measured and calculated gas-phase composition at the end of diffusion measurement. The newly developed technique can quantify the contributions of each component of mixture to the bulk mass transfer from gas into liquid. The effective diffusion coefficient of C3H8 in the C3H8-CO2 mixture at 3945 ± 20 kPa and 293.85 K, i.e., 18.19 × 10^{ - 10} {{m}}^{ 2} / {{s}}, is found to be much higher than CO2 at 3950 ± 18 kPa and 293.85 K, i.e., 8.68 × 10^{ - 10} {{m}}^{ 2} / {{s}}. In comparison with pure CO2, the presence of C3H8 in the C3H8-CO2 mixture contributes to a faster diffusion of CO2 from the gas phase into heavy oil and consequently a larger swelling factor of heavy oil.

[Effects of mercazolyl and L-thyroxine on the antiedematous activity of immunotropic preparations during development of toxic brain edema and swelling].

PubMed

Platonov, I A; Anashchenkova, T A; Andreeva, T A

2008-01-01

Dysfunction of thyroid gland plays an important role in the pathogenesis of brain edema and swelling. Toxic brain edema and swelling was modeled under condition of hypo- and hyperfunction of thyroid gland. Mercazolyl and L-thyroxine ambiguously influence the development of toxic brain edema and swelling in rats. L-thyroxin (35.7 microg/kg) favors increase in the water content in brain tissue, which can be considered as synergism with the edematous factor and the formation of brain tissue susceptibility to the development of brain edema and swelling. The administration of mercazolyl (5 mg/kg) and L-thyroxin (35.7 microg/kg) with thymogen (10 microg/kg), thymalin (1.2 mg/kg), cycloferon (0.5 mg/kg) results in decreasing brain tissue density as compared to intact animals. Dysfunction of the thyroid gland leads to changes in pharmacodynamics of immune preparations, which results in a decrease of their antiedematous activity.

THE SWELLING PROPERTIES OF SOIL ORGANIC MATTER AND THEIR RELATION TO SORPTION OF NON-IONIC ORGANIC COMPOUNDS

EPA Science Inventory

A method has been developed to measure the swelling properties of Concentrated natural organic materials in various organic liquids, and has been applied to various eat, pollen, chitin and cellulose samples. The swelling of these macromolecular aterials is rhe volumetric manifest...

SWELLING PROPERTIES OF SOIL ORGANIC MATTER AND THEIR RELATION TO SORPTION OF NON-IONIC ORGANIC COMPOUNDS

EPA Science Inventory

A method has been developed to measure the swelling properties of Concentrated natural organic materials in various organic liquids, and has been applied to various eat, pollen, chitin and cellulose samples. he swelling of these macromolecular aterials is rhe volumetric manifesta...

Injectable hydrogels with high fixed charge density and swelling pressure for nucleus pulposus repair: biomimetic glycosaminoglycan analogues.

PubMed

Sivan, S S; Roberts, S; Urban, J P G; Menage, J; Bramhill, J; Campbell, D; Franklin, V J; Lydon, F; Merkher, Y; Maroudas, A; Tighe, B J

2014-03-01

The load-bearing biomechanical role of the intervertebral disc is governed by the composition and organization of its major macromolecular components, collagen and aggrecan. The major function of aggrecan is to maintain tissue hydration, and hence disc height, under the high loads imposed by muscle activity and body weight. Key to this role is the high negative fixed charge of its glycosaminoglycan side chains, which impart a high osmotic pressure to the tissue, thus regulating and maintaining tissue hydration and hence disc height under load. In degenerate discs, aggrecan degrades and is lost from the disc, particularly centrally from the nucleus pulposus. This loss of fixed charge results in reduced hydration and loss of disc height; such changes are closely associated with low back pain. The present authors developed biomimetic glycosaminoglycan analogues based on sulphonate-containing polymers. These biomimetics are deliverable via injection into the disc where they polymerize in situ, forming a non-degradable, nuclear "implant" aimed at restoring disc height to degenerate discs, thereby relieving back pain. In vitro, these glycosaminoglycan analogues possess appropriate fixed charge density, hydration and osmotic responsiveness, thereby displaying the capacity to restore disc height and function. Preliminary biomechanical tests using a degenerate explant model showed that the implant adapts to the space into which it is injected and restores stiffness. These hydrogels mimic the role taken by glycosaminoglycans in vivo and, unlike other hydrogels, provide an intrinsic swelling pressure, which can maintain disc hydration and height under the high and variable compressive loads encountered in vivo. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Negative Pressure Wound Therapy with Surgical Gloves to Repair Soft Tissue Defects in Hands.

PubMed

Fujitani, Teruaki; Zenke, Yukichi; Shinone, Michitaka; Menuki, Kunitaka; Fukumoto, Keizo; Sakai, Akinori

2015-09-01

The efficacy of negative pressure wound therapy (NPWT) in the treatment of skin defect wounds has been established, but it is difficult to apply to hand surgery because of the easy occurrence of air leaks. We report two cases of performing NPWT with surgical gloves. Case1: A 37-year-old male was injured on his right dorsal hand from a punch. He presented to our hospital three days after the injury because of swelling and pain. The wound was infected and contused, so wound lavage and debridement (W&D) were performed under local anesthesia. The infected condition didn't improve after antimicrobial infusion, so W&D were performed again 8 days after the first visit. Then W&D were performed every day, and the infection subsided 15 days after the first visit. NPWT was initiated for the purpose of managing exudate and the wound condition, and healthy granulation tissue formed gradually. Finally, transpositional flap and full-thickness skin graft were performed on day 29. Case2: A 43-year-old male accidentally sustained a high pressure injection of oil into his dorsal hand. He presented to our hospital the next day, and W&D were performed. W&D were performed again two days after the first visit, and artificial dermis was applied over a part of the wound that was impossible to close. A decision was made to apply NPWT and a surgical glove for the purpose of reducing swelling and managing wound exudate. The swelling decreased and granulation tissue formed gradually, then nine days after the first visit a sural nerve graft was applied to bridge the defective area, and a full thickness skin graft was applied. We achieved good wound closure and hand function recovery after using NPWT and a surgical glove.

Separation of Solid Stress From Interstitial Fluid Pressure in Pancreas Cancer Correlates With Collagen Area Fraction.

PubMed

Nieskoski, Michael D; Marra, Kayla; Gunn, Jason R; Kanick, Stephen C; Doyley, Marvin M; Hasan, Tayyaba; Pereira, Stephen P; Stuart Trembly, B; Pogue, Brian W

2017-06-01

Elevated total tissue pressure (TTP) in pancreatic adenocarcinoma is often associated with stress applied by cellular proliferation and hydrated hyaluronic acid osmotic swelling; however, the causal roles of collagen in total tissue pressure have yet to be clearly measured. This study illustrates one direct correlation between total tissue pressure and increased deposition of collagen within the tissue matrix. This observation comes from a new modification to a conventional piezoelectric pressure catheter, used to independently separate and quantify total tissue pressure, solid stress (SS), and interstitial fluid pressure (IFP) within the same tumor location, thereby clarifying the relationship between these parameters. Additionally, total tissue pressure shows a direct correlation with verteporfin uptake, demonstrating the impediment of systemically delivered molecules with increased tissue hypertension.

Pathogenesis of Brain Edema and Investigation into Anti-Edema Drugs

PubMed Central

Michinaga, Shotaro; Koyama, Yutaka

2015-01-01

Brain edema is a potentially fatal pathological state that occurs after brain injuries such as stroke and head trauma. In the edematous brain, excess accumulation of extracellular fluid results in elevation of intracranial pressure, leading to impaired nerve function. Despite the seriousness of brain edema, only symptomatic treatments to remove edema fluid are currently available. Thus, the development of novel anti-edema drugs is required. The pathogenesis of brain edema is classified as vasogenic or cytotoxic edema. Vasogenic edema is defined as extracellular accumulation of fluid resulting from disruption of the blood-brain barrier (BBB) and extravasations of serum proteins, while cytotoxic edema is characterized by cell swelling caused by intracellular accumulation of fluid. Various experimental animal models are often used to investigate mechanisms underlying brain edema. Many soluble factors and functional molecules have been confirmed to induce BBB disruption or cell swelling and drugs targeted to these factors are expected to have anti-edema effects. In this review, we discuss the mechanisms and involvement of factors that induce brain edema formation, and the possibility of anti-edema drugs targeting them. PMID:25941935

Cardiac Mitochondria l Membrane Stability after Deep Hypothermia using a Xenon Clathrate Cryostasis Protocol – an Electron Microscopy Study

PubMed Central

Sheleg, Sergey; Hixon, Hugh; Cohen, Bruce; Lowry, David; Nedzved, Mikhail

2008-01-01

We investigated a new cryopreservation method using xenon, a clathrate-forming gas, under medium pressure (100psi). The objective of the study was to determine whether this cryostasis protocol could protect cardiac mitochondria at cryogenic temperatures (below 100 degrees Celsius).We analyzed transmission electron microscopy images to obtain information about changes in mitochondrial morphology induced by cryopreservation of the hearts. Our data showed absence of mitochondrial swelling, rupture of inner and outer membranes, and leakage of mitochondrial matrix into the cytoplasm after applying this cryostasis protocol. The electron microscopy results provided the first evidence that a cryostasis protocol using xenon as a clathrate-forming gas under pressure may have protective effects on intracellular membranes. This cryostasis technology may find applications in developing new approaches for long-term cryopreservation protocols. PMID:18787624

Modelling heat and mass transfer in bread baking with mechanical deformation

NASA Astrophysics Data System (ADS)

Nicolas, V.; Salagnac, P.; Glouannec, P.; Ploteau, J.-P.; Jury, V.; Boillereaux, L.

2012-11-01

In this paper, the thermo-hydric behaviour of bread during baking is studied. A numerical model has been developed with Comsol Multiphysics© software. The model takes into account the heat and mass transfers in the bread and the phenomenon of swelling. This model predicts the evolution of temperature, moisture, gas pressure and deformation in French "baguette" during baking. Local deformation is included in equations using solid phase conservation and, global deformation is calculated using a viscous mechanic model. Boundary conditions are specified with the sole temperature model and vapour pressure estimation of the oven during baking. The model results are compared with experimental data for a classic baking. Then, the model is analysed according to physical properties of bread and solicitations for a better understanding of the interactions between different mechanisms within the porous matrix.

Developmental adaptations to gravity in animals

NASA Technical Reports Server (NTRS)

Hargens, Alan R.

1991-01-01

Terrestrial animals have adapted to a constant gravitational stress over millions of years. Tissues of the cardiovascular system and lumbar spine in tall species of animals such as the giraffe are particularly well adapted to high and variable vectors of gravitational force. Swelling of the leg tissues in the giraffe is prevented by a variety of physiological mechanisms including (1) a natural 'antigravity suit', (2) impermeable capillaries, (3) arterial-wall hypertrophy, (4) variable blood pressures during normal activity, and (5) a large-capacity lymphatic system. These adaptations, as well as a natural hypertension, maintain blood perfusion to the giraffe's brain. The intervertebral disk is another tissue that is uniquely adapted to gravitational stress. Tall and large terrestrial animals have higher swelling pressures than their smaller or aquatic counterparts. Finally, the meniscus of the rabbit knee provides information on the effects of aging and load-bearing on cartilaginous tissues. Such tissues within the joints of animals are important for load-bearing on Earth; these connective tissues may degenerate during long-duration space flight.

The mechanics of decompressive craniectomy: Bulging in idealized geometries

NASA Astrophysics Data System (ADS)

Weickenmeier, Johannes; Kuhl, Ellen; Goriely, Alain

2016-11-01

In extreme cases of traumatic brain injury or a stroke, the resulting uncontrollable swelling of the brain may lead to a harmful increase of the intracranial pressure. As a common measure for immediate release of pressure on the brain, part of the skull is surgically removed allowing for the brain to bulge outwards, a procedure known as a decompressive craniectomy. During this excessive brain swelling, the affected tissue typically undergoes large deformations resulting in a complex three-dimensional mechanical loading state with several important implications on optimal treatment strategies and outcome. Here, as a first step towards a better understanding of the mechanics of a decompressive craniectomy, we consider simple models for the bulging of elastic solids under geometric constraints representative of the surgical intervention. In small deformations and simple geometries, the exact solution of this problem is derived from the theory of contact mechanics. The analysis of these solutions reveals a number of interesting generic features relevant for the mechanics of craniectomy.

Familial Schwannomatosis: A Diagnostic Challenge

PubMed Central

Butala, Rajendra Prasad R.; Shetty, Sunil H; Khedekar, Ravindra G

2017-01-01

Schwannomatosis is a disease characterized by the development of multiple benign tumours originating from Schwann cells. Schwannomatosis is a member of the family of diseases known as Neurofibromatosis (NF). Patients with Schwannomatosis develop multiple Schwannomas on cranial, spinal and peripheral nerves. We report a rare case of a 60-year-old female who presented with a painful swelling on the ulnar aspect of her distal forearm. She underwent an excisional biopsy for it; which was suggestive of a Schwannoma. Following ulnar swelling surgery, she developed acute low back pain, which was burning in nature with radiation along both lower limbs without any neurovascular deficit. She was treated conservatively, failing which an MRI was performed which suggested abnormal lesions in the intradural extra medullary compartment of the spinal canal. She had multiple swellings over the entire body with a positive family history of similar swellings in her sister and nephew. The painful lumbar swellings were excised which on histopathological examination revealed to be Schwannomas. No neurological deficit was observed postoperatively. There were no neurocutaneous markers, axillary freckling, visual or auditory disturbances seen in the patient or her relatives. Any patient with multiple painful progressive swellings in the body without the characteristic features of NF-1 and NF-2 should raise the suspicion of Schwannomatosis. PMID:28384950

Familial Schwannomatosis: A Diagnostic Challenge.

PubMed

Mansukhani, Sameer Ajit; Butala, Rajendra Prasad R; Shetty, Sunil H; Khedekar, Ravindra G

2017-02-01

Schwannomatosis is a disease characterized by the development of multiple benign tumours originating from Schwann cells. Schwannomatosis is a member of the family of diseases known as Neurofibromatosis (NF). Patients with Schwannomatosis develop multiple Schwannomas on cranial, spinal and peripheral nerves. We report a rare case of a 60-year-old female who presented with a painful swelling on the ulnar aspect of her distal forearm. She underwent an excisional biopsy for it; which was suggestive of a Schwannoma. Following ulnar swelling surgery, she developed acute low back pain, which was burning in nature with radiation along both lower limbs without any neurovascular deficit. She was treated conservatively, failing which an MRI was performed which suggested abnormal lesions in the intradural extra medullary compartment of the spinal canal. She had multiple swellings over the entire body with a positive family history of similar swellings in her sister and nephew. The painful lumbar swellings were excised which on histopathological examination revealed to be Schwannomas. No neurological deficit was observed postoperatively. There were no neurocutaneous markers, axillary freckling, visual or auditory disturbances seen in the patient or her relatives. Any patient with multiple painful progressive swellings in the body without the characteristic features of NF-1 and NF-2 should raise the suspicion of Schwannomatosis.

Characterization of the Rheological and Swelling Properties of Synthetic Alkali Silicate Gels in Order to Predict Their Behavior in ASR Damaged Concrete

NASA Astrophysics Data System (ADS)

Vayghan, Asghar Gholizadeh

Alkali-silica reaction (ASR) is a major concrete durability concern that is responsible for the deterioration of concrete infrastructure in the world. The resultant of the reaction between the cement alkali hydroxides and the metastable silicates in the aggregates is a hygroscopic and expansive alkali-silicate gel (referred to as ASR gel in this document). The swelling behavior of ASR gels determines the extent of damage to concrete structures and, as such, mitigation of ASR relies on understanding these gels and finding ways to prevent them either from formation, or from swelling after formation. This dissertation focuses on the synthesis and characterization of ASR gels with wide ranges of compositions similar to what has been reported for the filed ASR gels in the literature. The experimental work consisted of three phases as follow. Phase I: Investigation of rheology, chemistry and physics of ASR gels produced through sol-method. Inspired from the existing literature, two sol-gel methods have been developed for the synthesis of ASR gels. The rheological (primarily gelation time, yield stress, and equilibrium stress), chemical (pore solution pH, pore solution composition, osmotic pressure, solid phase composition, stoichiometry of gelation reactions) and physical (evaporable water, solid content, etc.) properties of synthetic ASR gels have been extensively investigated in this phase. Ca/Si, Na/Si and K/Si, and water content were considered as the main chemical composition variables. In order to investigate the suppressing effects of lithium on the swelling properties of ASR gels, the gels were added with lithium in a part of the experimental program. The results strongly suggested that Ca/Si has a positive effect on the yield stress of the gels and their rate of gelation. Na/Si was found to have a decreasing effect on the yield stress and gelation rate (especially at low Ca/Si levels). K/Si and Li/Si had second-order (i.e., polynomial) effects on the yield stress of the gels, causing a significant drop in this parameter followed by some increase as they approached their upper values. Na/Si and K/Si were both found contribute to the osmotic potential of the ASR gels, while increase in Ca/Si generally led to a drop in this parameter. The presence of all components (Ca, Na, and K) were found to contribute to the pH of the gels' pore solution, and Ca/Si and Na/Si showed a synergistic effect on this parameter. Lithium, on the other hand, was found to be able to drop the OH- concentration of the pore solution by a factor of five in the case of high-sodium gels, which could partially explain its ASR mitigating effect. Phase II: Investigation of the free and restrained swelling behavior, hydrophilic potential and viscoelastic properties of ASR gels produced through the "paste method". 20 gel compositions were selected (using the central composite design method) with Ca/Si, Na/Si and K/Si molar ratios varying in the ranges (0.05-0.5), (0.1-1.0) and (0.0-0.3), respectively. The gels were produced by batching appropriate amounts of certain precursors containing different chemical components. After curing, the gels were tested for the abovementioned parameters using some innovative test methods as explained in the relevant chapters. The results suggest that increasing the alkali content (Na/Si and K/Si) in ASR gels resulted in an increase in the gels' free swelling and water absorption, and a reduction in the equilibrium relative humidity (ERH). However, no significant effect was found for Ca/Si with respect to the ERH. Ca/Si was found to have a multi-episode effect on the swelling and water absorption properties of the gels. An increase in Ca/Si up to 0.18 led to a considerable reduction in the swelling strain, followed by a slight increasing effect as it approached 0.4. Further increase in Ca/Si resulted in complete elimination of swelling strain. While Na/Si and K/Si could constantly increase the free swelling strain, their excessive presence was found to have a softening effect on the gels' structure, leading to a drop in their swelling pressure. Finally, all gels were found to show viscoelastic behavior that could be best explained via Burger's model. The elastic and viscous components have been measured for each gel and related to their composition using regression. Phase III: An Extended Chemical Index Model to Predict the Fly Ash Dosage Necessary for Mitigating Alkali-Silica Reaction in Concrete . In order to have an applied and ready-to-implement contribution to the realm of alkali-silica reaction, a predictive statistical model was developed that determines the optimum fly ash dosage for ASR mitigation depending on the acceptable risk of ASR and structure's importance. (Abstract shortened by ProQuest.).

Activation of a Ca-bentonite as buffer material

NASA Astrophysics Data System (ADS)

Huang, Wei-Hsing; Chen, Wen-Chuan

2016-04-01

Swelling behavior is an important criterion in achieving the low-permeability sealing function of buffer material. A potential buffer material may be used for radioactive waste repository in Taiwan is a locally available clayey material known as Zhisin clay, which has been identified as a Ca-bentonite. Due to its Ca-based origin, Zhisin was found to exhibit swelling capacity much lower than that of Na-bentonite. To enhance the swelling potential of Zhisin clay, a cation exchange process by addition of Na2CO3 powder was introduced in this paper. The addition of Na2CO3 reagent to Zhisin clay, in a liquid phase, caused the precipitation of CaCO3 and thereby induced a replacement of Ca2+ ions by Na+ ions on the surface of bentonite. Characterization test conducted on Zhisin clay includes chemical analysis, cation exchange capacity, X-ray diffraction, and thermogravimetry (TG). Free-swelling test apparatus was developed according to International Society of Rock Mechanics recommendations. A series of free-swelling tests were conducted on untreated and activated specimens to characterize the effect of activation on the swelling capacity of Zhisin clay. Efforts were made to determine an optimum dosage for the activation, and to evaluate the aging effect. Also, the activated material was evaluated for its stability in various hydrothermal conditions for potential applications as buffer material in a repository. Experimental results show that Na2CO3-activated Zhisin clay is superior in swelling potential to untreated Zhisin clay. Also, there exists an optimum amount of activator in terms of improvements in the swelling capacity. A distinct time-swell relationship was discovered for activated Zhisin clay. The corresponding mechanism refers to exchange of cations and breakdown of quasi-crystal, which results in ion exchange hysteresis of Ca-bentonite. Due to the ion exchange hysteresis, activated bentonite shows a post-rise time-swell relationship different than the sigmoid-shaped time-swell curves of typical bentonites. That is, a greater part of swelling strain develops after the completion of primary swelling strain. At an optimal amount of 1% Na2CO3 in weight, the maximum swelling strain was found to be 3 times as much as that of untreated Zhisin clay. Furthermore, the Na2CO3-activated Zhisin clay exhibited improved resistance to thermal environments and behaved similar to Na-type bentonites under various hydrothermal temperatures.

Full Characterization of CO2-Oil Properties On-Chip: Solubility, Diffusivity, Extraction Pressure, Miscibility, and Contact Angle.

PubMed

Sharbatian, Atena; Abedini, Ali; Qi, ZhenBang; Sinton, David

2018-02-20

Carbon capture, storage, and utilization technologies target a reduction in net CO 2 emissions to mitigate greenhouse gas effects. The largest such projects worldwide involve storing CO 2 through enhanced oil recovery-a technologically and economically feasible approach that combines both storage and oil recovery. Successful implementation relies on detailed measurements of CO 2 -oil properties at relevant reservoir conditions (P = 2.0-13.0 MPa and T = 23 and 50 °C). In this paper, we demonstrate a microfluidic method to quantify the comprehensive suite of mutual properties of a CO 2 and crude oil mixture including solubility, diffusivity, extraction pressure, minimum miscibility pressure (MMP), and contact angle. The time-lapse oil swelling/extraction in response to CO 2 exposure under stepwise increasing pressure was quantified via fluorescence microscopy, using the inherent fluorescence property of the oil. The CO 2 solubilities and diffusion coefficients were determined from the swelling process with measurements in strong agreement with previous results. The CO 2 -oil MMP was determined from the subsequent oil extraction process with measurements within 5% of previous values. In addition, the oil-CO 2 -silicon contact angle was measured throughout the process, with contact angle increasing with pressure. In contrast with conventional methods, which require days and ∼500 mL of fluid sample, the approach here provides a comprehensive suite of measurements, 100-fold faster with less than 1 μL of sample, and an opportunity to better inform large-scale CO 2 projects.

Permeability of sediment cores from methane hydrate deposit in the Eastern Nankai Trough, Japan

NASA Astrophysics Data System (ADS)

Konno, Y.; Yoneda, J.; Egawa, K.; Ito, T.; Jin, Y.; Kida, M.; Suzuki, K.; Nakatsuka, Y.; Nagao, J.

2013-12-01

Effective and absolute permeability are key parameters for gas production from methane-hydrate-bearing sandy sediments. Effective and/or absolute permeability have been measured using methane-hydrate-bearing sandy cores and clayey and silty cores recovered from Daini Atsumi Knoll in the Eastern Nankai Trough during the 2012 JOGMEC/JAPEX Pressure coring operation. Liquid-nitrogen-immersed cores were prepared by rapid depressurization of pressure cores recovered by a pressure coring system referred to as the Hybrid PCS. Cores were shaped cylindrically on a lathe with spraying of liquid nitrogen to prevent hydrate dissociation. Permeability was measured by a flooding test or a pressure relaxation method under near in-situ pressure and temperature conditions. Measured effective permeability of hydrate-bearing sediments is less than tens of md, which are order of magnitude less than absolute permeability. Absolute permeability of clayey cores is approximately tens of μd, which would perform a sealing function as cap rocks. Permeability reduction due to a swelling effect was observed for a silty core during flooding test of pure water mimicking hydrate-dissociation-water. Swelling effect may cause production formation damage especially at a later stage of gas production from methane hydrate deposits. This study was financially supported by the Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium) that carries out Japan's Methane Hydrate R&D Program conducted by the Ministry of Economy, Trade and Industry (METI).

Evolution of water repellency of organic growing media used in Horticulture and consequences on hysteretic behaviours of the water retention curve

NASA Astrophysics Data System (ADS)

Michel, Jean-Charles; Qi, Guifang; Charpentier, Sylvain; Boivin, Pascal

2010-05-01

Most of growing media used in horticulture (particularly peat substrates) shows hysteresis phenomena during desiccation and rehydration cycles, which greatly affects their hydraulic properties. The origins of these properties have often been related to one or several of the specific mechanisms such as the non-geometrical uniformity of the pores (also called ‘ink bottle' effect), presence of trapped air, shrinkage-swelling phenomena, and changes in water repellency. However, recent results showed that changes in wettability during desiccation and rehydration could be considered as one of the main factors leading to hysteretic behaviour in these materials with high organic matter contents (Naasz et al., 2008). The general objective was to estimate the evolutions of changes in water repellency on the water retention properties and associated hysteresis phenomena in relation to the intensity and the number of drying/wetting cycles. For this, simultaneous shrinkage/swelling and water retention curves were obtained using method previously developed for soil shrinkage analysis by Boivin (2006) that we have adapted for growing media and to their physical behaviours during rewetting. The experiment was performed in a climatic chamber at 20°C. A cylinder with the growing medium tested was placed on a porous ceramic disk which is used to control the pressure and to full/empty water of the sample. The whole of the device was then placed on a balance to record the water loss/storage with time; whereas linear displacement transducers were used to measure the changes in sample height and diameter upon drying and wetting in the axial and radial directions. Ceramic cups (2 cm long and 0.21 cm diameter) connected to pressure transducers were inserted in the middle of the samples to record the water pressure head. In parallell, contact angles were measured by direct droplet method at different steps during the drying/rewetting cycles. First results obtained on weakly decomposed peat samples with or without surfactants showed isotropic shrinkage and swelling, and highlighted hysteresis phenomena in relation to the intensity of drying/wetting cycle. Contact angle measurements are in progress. Other measurements on highly decomposed peat (more repellent than weakly decomposed), composted pine bark (without volume change during dryin/wetting cycles), and coco fiber (expected as non repellent organic growing media) are also in progress.

Historical Material Analysis of DC745U Pressure Pads

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

Ortiz-Acosta, Denisse

As part of the Enhance Surveillance mission, it is the goal to provide suitable lifetime assessment of stockpile materials. This report is an accumulation of historical publication on the DC745U material and their findings. It is the intention that the B61 LEP program uses this collection of data to further develop their understanding and potential areas of study. DC745U is a commercially available silicone elastomer consisting of dimethyl, methyl-phenyl, and methyl-vinyl siloxane repeat units. Originally, this material was manufactured by Dow Corning as Silastic{reg_sign} DC745U at their manufacturing facility in Kendallville, IN. Recently, Dow Corning shifted this material to themore » Xiameter{reg_sign} brand product line. Currently, DC745U is available through Xiameter{reg_sign} or Dow Corning's distributor R. D. Abbott Company. DC745U is cured using 0.5 wt% vinyl-specific peroxide curing agent known as Luperox 101 or Varox DBPH-50. This silicone elastomer is used in numerous parts, including two major components (outer pressure pads and aft cap support) in the W80 and as pressure pads on the B61. DC745U is a proprietary formulation, thus Dow Corning provides limited information on its composition and properties. Based on past experience with Dow Corning, DC745U is at risk of formulation changes without notification to the costumer. A formulation change for DC745U may have a significant impact because the network structure is a key variable in determining material properties. The purpose of this report is to provide an overview of historical DC745U studies and identify gaps that need to be addressed in future work. Some of the previous studies include the following: 1. Spectroscopic characterization of raw gum stock. 2. Spectroscopic, thermal, and mechanical studies on cured DC745U. 3. Nuclear Magnetic Resonance (NMR) and solvent swelling studies on DC745U with different crosslink densities. 4. NMR, solvent swelling, thermal, and mechanical studies on thermally aged DC745U. 5. NMR, solvent swelling, thermal, and mechanical studies on radiolytically aged DC745U. Each area is reviewed and further work is suggested to improve our understanding of DC745U for systems engineering, surveillance, aging assessments, and lifetime assessment.« less

Traumatic brain injury and hemorrhagic shock: evaluation of different resuscitation strategies in a large animal model of combined insults.

PubMed

Jin, Guang; DeMoya, Marc A; Duggan, Michael; Knightly, Thomas; Mejaddam, Ali Y; Hwabejire, John; Lu, Jennifer; Smith, William Michael; Kasotakis, Georgios; Velmahos, George C; Socrate, Simona; Alam, Hasan B

2012-07-01

Traumatic brain injury (TBI) and hemorrhagic shock (HS) are the leading causes of trauma-related mortality and morbidity. Combination of TBI and HS (TBI + HS) is highly lethal, and the optimal resuscitation strategy for this combined insult remains unclear. A critical limitation is the lack of suitable large animal models to test different treatment strategies. We have developed a clinically relevant large animal model of TBI + HS, which was used to evaluate the impact of different treatments on brain lesion size and associated edema. Yorkshire swine (42-50 kg) were instrumented to measure hemodynamic parameters and intracranial pressure. A computer-controlled cortical impact device was used to create a TBI through a 20-mm craniotomy: 15-mm cylindrical tip impactor at 4 m/s velocity, 100-ms dwell time, and 12-mm penetration depth. Volume-controlled hemorrhage was started (40% blood volume) concurrent with the TBI. After 2 h of shock, animals were randomized to one of three resuscitation groups (n = 5/group): (a) normal saline (NS); (b) 6% hetastarch, Hextend (Hex); and (c) fresh frozen plasma (FFP). Volumes of Hex and FFP matched the shed blood, whereas NS was three times the volume. After 6 h of postresuscitation monitoring, brains were sectioned into 5-mm slices and stained with TTC (2,3,5-triphenyltetrazolium chloride) to quantify the lesion size and brain swelling. Combination of 40% blood loss with cortical impact and a period of shock (2 h) resulted in a highly reproducible brain injury. Total fluid requirements were lower in the Hex and FFP groups. Lesion size and brain swelling in the FFP group (2,160 ± 202.63 mm and 22% ± 1.0%, respectively) were significantly smaller than those in the NS group (3,285 ± 130.8 mm3 and 37% ± 1.6%, respectively) (P < 0.05). Hex treatment decreased the swelling (29% ± 1.6%) without reducing the lesion size. Early administration of FFP reduces the size of brain lesion and associated swelling in a large animal model of TBI + HS. In contrast, artificial colloid (Hex) decreases swelling without reducing the actual size of the brain lesion.

Marked potentiation of cell swelling by cytokines in ammonia-sensitized cultured astrocytes

PubMed Central

2010-01-01

Background Brain edema leading to high intracranial pressure is a lethal complication of acute liver failure (ALF), which is believed to be cytotoxic due to swelling of astrocytes. In addition to the traditional view that elevated levels of blood and brain ammonia are involved in the mechanism of brain edema in ALF, emerging evidence suggests that inflammatory cytokines also contribute to this process. We earlier reported that treatment of astrocyte cultures with a pathophysiological concentration of ammonia (5 mM NH4Cl) resulted in the activation of nuclear factor-kappaB (NF-κB) and that inhibition of such activation diminished astrocyte swelling, suggesting a key role of NF-κB in the mechanism of ammonia-induced astrocyte swelling. Since cytokines are also well-known to activate NF-κB, this study examined for additive/synergistic effects of ammonia and cytokines in the activation of NF-κB and their role in astrocyte swelling. Methods Primary cultures of astrocytes were treated with ammonia and cytokines (TNF-α, IL-1, IL-6, IFN-γ, each at 10 ng/ml), individually or in combination, and cell volume was determined by the [3H]-O-methylglucose equilibration method. The effect of ammonia and cytokines on the activation of NF-κB was determined by immunoblots. Results Cell swelling was increased by ammonia (43%) and by cytokines (37%) at 24 h. Simultaneous co-treatment with cytokines and ammonia showed no additional swelling. By contrast, cultures pretreated with ammonia for 24 h and then exposed to cytokines for an additional 24 h, showed a marked increase in astrocyte swelling (129%). Treatment of cultures with ammonia or cytokines alone also activated NF-κB (80-130%), while co-treatment had no additive effect. However, in cultures pre-treated with ammonia for 24 h, cytokines induced a marked activation of NF-κB (428%). BAY 11-7082, an inhibitor of NF-κB, completely blocked the astrocyte swelling in cultures pre-treated with ammonia and followed by the addition of a mixture of cytokines. Conclusion Our results indicate that ammonia and a mixture of cytokines each cause astrocyte swelling but when these agents are added simultaneously, no additive effects were found. On the other hand, when cells were initially treated with ammonia and 24 h later given a mixture of cytokines, a marked potentiation in cell swelling and NF-κB activation occurred. These data suggest that the potentiation in cell swelling is a consequence of the initial activation of NF-κB by ammonia. These findings provide a likely mechanism for the exacerbation of brain edema in patients with ALF in the setting of sepsis/inflammation. PMID:20942959

Development of a lameness model in sheep for assessing efficacy of analgesics.

PubMed

Colditz, I G; Paull, D R; Hervault, G; Aubriot, D; Lee, C

2011-08-01

To develop a lameness model to assess the efficacy of analgesics for alleviating pain, swelling and systemic signs of inflammation in sheep. The response to subcutaneous injection of 0.1 or 0.2 mL turpentine in a forelimb pastern (n = 4 ewes per dose) was examined at 0, 3, 6, 24, 48 and 72 h. In a second experiment, responses were measured at 0, 2, 4, 6, 8, 10, 12 and 24 h in ewes receiving 0.1 mL turpentine ± meloxicam 1 mg/kg IV at 0 h (n = 6 per group). Responses measured included forceplate pressure, skin temperature, limb circumference, nociception, leucocyte count, neutrophil : lymphocyte ratio, haptoglobin and daily feed intake. Turpentine injection caused a decrease in weight borne on the treated limb, increased skin temperature, increased sensitivity at the injection site and leucocytosis by 2 h and increased limb circumference by 4 h. Weight borne and sensitivity of the injected limb returned to control levels after around 24 h, whereas tissue swelling, elevated skin temperature and elevated haptoglobin levels persisted for at least 72 h. Treatment with meloxicam improved weight borne by and tolerance to pressure exerted on the turpentine-injected limb. The local and systemic signs of inflammation and pain, temporary reduction in function of the affected limb and partial amelioration of some of these changes by the dose of meloxicam used here suggest that injection of turpentine in the lower forelimb provides a suitable model for examining the efficacy of analgesics for alleviation of pain and inflammation in sheep. © 2011 The Authors. Australian Veterinary Journal © 2011 Australian Veterinary Association.

Mechanical stimulation by osmotic and hydrostatic pressure activates Drosophila oocytes in vitro in a calcium-dependent manner

PubMed Central

Horner, Vanessa L.; Wolfner, Mariana F.

2008-01-01

Summary Embryogenesis in vertebrates and marine invertebrates begins when a mature oocyte is fertilized, resulting in a rise in intracellular calcium (Ca2+) that activates development. Insect eggs activate without fertilization via an unknown signal imparted to the egg during ovulation or egg laying. One hypothesis for the activating signal is that deformation of eggs as they pass through a tight orifice provides a mechanical stimulus to trigger activation. Ovulation could produce two forms of mechanical stimulus: external pressure resulting from the passage of oocytes from the ovary into the narrow oviducts, and osmotic pressure caused by hydration-induced swelling of the oocyte within the oviducts. Ovulation could also trigger activation by placing the oocyte in a new environment that contains an activating substance, such as a particular ion. Here, we provide the first evidence that Drosophila oocytes require Ca2+ for activation, and that activation can be triggered in vitro by mechanical stimuli, specifically osmotic and hydrostatic pressure. Our results suggest that activation in Drosophila is triggered by a mechanosensitive process that allows external Ca2+ to enter the oocyte and drive the events of activation. This will allow exploitation of Drosophila genetics to dissect molecular pathways involving Ca2+ and the activation of development. PMID:18304524

The effect of cyclic hydrostatic pressure on the functional development of cartilaginous tissues engineered using bone marrow derived mesenchymal stem cells.

PubMed

Meyer, E G; Buckley, C T; Steward, A J; Kelly, D J

2011-10-01

Mechanical signals can play a key role in regulating the chondrogenic differentiation of mesenchymal stem cells (MSCs). The objective of this study was to determine if the long-term application of cyclic hydrostatic pressure could be used to improve the functional properties of cartilaginous tissues engineered using bone marrow derived MSCs. MSCs were isolated from the femora of two porcine donors, expanded separately under identical conditions, and then suspended in cylindrical agarose hydrogels. Constructs from both donors were maintained in a chemically defined media supplemented with TGF-β3 for 42 days. TGF-β3 was removed from a subset of constructs from day 21 to 42. Loaded groups were subjected to 10 MPa of cyclic hydrostatic pressurisation at 1 Hz for one hour/day, five days/week. Loading consisted either of continuous hydrostatic pressure (CHP) initiated at day 0, or delayed hydrostatic pressure (DHP) initiated at day 21. Free swelling (FS) constructs were cultured in parallel as controls. Constructs were assessed at days 0, 21 and 42. MSCs isolated from both donors were morphologically similar, demonstrated comparable colony forming unit-fibroblast (CFU-F) numbers, and accumulated near identical levels of collagen and GAG following 42 days of free swelling culture. Somewhat unexpectedly the two donors displayed a differential response to hydrostatic pressure. For one donor the application of CHP resulted in increased collagen and GAG accumulation by day 42, resulting in an increased dynamic modulus compared to FS controls. In contrast, CHP had no effect on matrix accumulation for the other donor. The application of DHP had no effect on either matrix accumulation or construct mechanical properties for both donors. Variability in the response to hydrostatic pressure was also observed for three further donors. In conclusion, this study demonstrates that the application of long-term hydrostatic pressure can be used to improve the functional properties of cartilaginous tissues engineered using bone marrow derived MSCs by enhancing collagen and GAG accumulation. The response to such loading however is donor dependent, which has implications for the clinical utilisation of such a stimulus when engineering cartilaginous grafts using autologous MSCs. Copyright © 2011 Elsevier Ltd. All rights reserved.

Prevertebral space effusion caused by the breaking of swollen lymphonodi retropharynici in nasopharyngeal carcinoma: A case report.

PubMed

Liu, Lian-Hua; Yang, Xiao-Feng

2016-06-01

A 20-year-old male presented to hospital with blood in the mucus, which had occurred for 6 months, and was diagnosed with nasopharyngeal carcinoma (NPC). Due to passive smoking, the patient developed a constant and violent cough, pain behind the right ear and swelling of the retropharynx. The results of a computed tomography scan, which was performed during re-examination of the patient, revealed that the right lymphonodi retropharynici had decreased in size and the hypodense shadow of the prevertebral space had become clear. Therefore, the retropharyngeal pressure was suspected to be increased due to the violent cough. Consequently, the increased pressure may have caused the swollen lymph nodes on the right side of the pharynx to break, which allowed the necrotic liquid to seep into the prevertebral space and result in effusion. Subsequent to 5 days of treatment with methylprednisolone (40 mg ivgtt qd, d1-5), the results from the cone bean computed tomography examination, which had been performed prior to radiotherapy, indicated that the retropharyngeal swelling had improved and the prevertebral space had returned to normal. To the best of our knowledge, the present study is the first reported case of effusion in the prevertebral space caused by the breaking of swollen lymphonodi retropharynici in NPC. The present study acts as a reminder of the possible delays in the treatments for head and neck tumor patients that demonstrate swollen retropharyngeal lymph nodes due to the occurrence of effusion in the prevertebral space.

Tracking the attenuation and nonbreaking dissipation of swells using altimeters

NASA Astrophysics Data System (ADS)

Jiang, Haoyu; Stopa, Justin E.; Wang, He; Husson, Romain; Mouche, Alexis; Chapron, Bertrand; Chen, Ge

2016-02-01

A method for systematically tracking swells across oceanic basins is developed by taking advantage of high-quality data from space-borne altimeters and wave model output. The evolution of swells is observed over large distances based on 202 swell events with periods ranging from 12 to 18 s. An empirical attenuation rate of swell energy of about 4 × 10-7 m-1 is estimated using these observations, and the nonbreaking energy dissipation rates of swells far away from their generating areas are also estimated using a point source model. The resulting acceptance range of nonbreaking dissipation rates is -2.5 to 5.0 × 10-7 m-1, which corresponds to a dissipation e-folding scales of at least 2000 km for steep swells, to almost infinite for small-amplitude swells. These resulting rates are consistent with previous studies using in-situ and synthetic aperture radar (SAR) observations. The frequency dispersion and angular spreading effects during swell propagation are discussed by comparing the results with other studies, demonstrating that they are the two dominant processes for swell height attenuation, especially in the near field. The resulting dissipation rates from these observations can be used as a reference for ocean engineering and wave modeling, and for related studies such as air-sea and wind-wave-turbulence interactions.

Clinical characteristics of acute encephalopathy with acute brain swelling: A peculiar type of acute encephalopathy.

PubMed

Nukui, Megumi; Kawawaki, Hisashi; Inoue, Takeshi; Kuki, Ichiro; Okazaki, Shin; Amo, Kiyoko; Togawa, Masao; Ishikawa, Junichi; Rinka, Hiroshi; Shiomi, Masashi

2018-06-07

Acute encephalopathy has been observed with acute brain swelling (ABS) that is characterized by rapid progression to whole-brain swelling. The objective of this study was to describe the clinical characteristics of ABS. We encountered four patients with ABS and retrospectively investigated their clinical data with a medical chart review. Three patients had seizure clustering or status epilepticus in the clinical course. Signs of elevated intracranial pressure (ICP) appeared 3-9 h after the first convulsive attack in three patients. In all patients, signs of brainstem involvement appeared 1-8 h after signs of elevated ICP. Mild hyponatremia that progressed after signs of elevated ICP appeared was noted in three patients. Brain CT revealed mild brain swelling in the initial phase, which rapidly progressed to whole-brain swelling. No focal abnormalities were detected on brain MRI in one patient. Continuous electroencephalography was initially normal, but in two patients, high-amplitude slow waves appeared with rapid changes before signs of brainstem involvement. Although recovery was achieved without sequelae in two patients, outcome was fatal for the other two. The pathogenesis of ABS has yet to be clarified, but clinical features in our patients are not consistent with any established subtypes of acute encephalopathy. Therefore, we believe that ABS should be recognized as a new type of acute encephalopathy. Copyright © 2018 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

Release profiles of phenytoin from new oral dosage form for the elderly.

PubMed

Watanabe, A; Hanawa, T; Sugihara, M; Yamamoto, K

1994-08-01

Utilization of the solid mass containing phenytoin, sodium caseinate and microcrystalline cellulose (MCC) as a new dosage form for the elderly was studied. The solid mass was prepared by treatment of the powder mixture with high pressure steam at 115 degrees C for 10 min. The stability of phenytoin in the solid mass was confirmed by infrared spectroscopy and high performance liquid chromatography. The extent of swelling of the solid mass containing phenytoin was investigated by water absorption test and gel strength test, and the swelling property was almost independent of the presence of phenytoin. The release profile of phenytoin from the solid mass was determined under various conditions, and was found to be influenced by the extent of swelling and the swollen state. It was observed that the protein adsorption to the phenytoin crystal surface and the addition of digestive enzyme also affected the release profile. In water, the solid mass prepared from a ground mixture of phenytoin and MCC showed remarkable improvement of release profile of phenytoin.

Upper crustal structure of the Hawaiian Swell from seafloor compliance measurements

NASA Astrophysics Data System (ADS)

Doran, A. K.; Laske, G.

2017-12-01

We present new constraints on elastic properties of the marine sediments and crust surrounding the Hawaiian Islands derived from seafloor compliance measurements. We analyze long-period seismic and pressure data collected during the Plume-Lithosphere Undersea Mantle Experiment [Laske et al, 2009], a deployment consisting of nearly 70 broadband ocean-bottom seismometers with an array aperture of over 1000 kilometers. Our results are supported by previous reflection & refraction studies and by direct sampling of the crust from regional drilling logs. We demonstrate the importance of simultaneously modeling density, compressional velocity, and shear velocity, the former two of which are often ignored during compliance investigations. We find variable sediment thickness and composition across the Hawaiian Swell, with the thickest sediments located within the Hawaiian Moat. Improved resolution of near-surface structure of the Hawaiian Swell is crucially important to improve tomographic images of the underlying lithosphere and asthenosphere and to address outstanding questions regarding the size, source, and location of the hypothesized mantle plume.

An Evaluation of the Softperm Contact Lens in the Simulated Aircraft Environment

DTIC Science & Technology

1991-01-01

potential effect on the eye of low atmospheric pressure and resultant low oxygen pressure that occurs with increased altitude. The cornea, which is avascular ... avascularity as well as its morphology and chemical composition. The epithelial cells are not keratinized and their components have a uniform index of refraction...noted that cell damage and/or necrosis was much less likely to occur if cellular swelling does not occur. They observed no epithelial staining in their

Spinal Cord Swelling and Alterations in Hydrostatic Pressure after Acute Injury

DTIC Science & Technology

2015-10-01

after SCI, half of the animals that received a duraplasty after SCI (50%) were already capable of weight-supported rhythmic hindlimb movements or...actual force, displacement or velocity at impact. Correlation analysis demonstrated a linear relationship between PTIBS and body weight after SCI

Morphological study on the pressure ulcer-like dermal lesions formed in the rat heel skin after transection of the sciatic nerves.

PubMed

Haba, Daijiro; Minami, Chie; Miyagawa, Miki; Arakawa, Takamitsu; Miki, Akinori

2017-01-01

Due to transection of bilateral sciatic nerves, pressure ulcer-like dermal lesion occurred in the hairy skin covering of the heel skin in almost all rats. In the present study, chronological changes of the rat heel skin after the transection were morphologically and immunohistochemically examined. In the heel skin, redness and swelling began by 3days after the operation, and open wound formed by 17days. At the redness and swelling stage, edema extensively occurred in the dermis. At the thickening stage, the epidermis at the pressed site became transiently thicker, and at the whitening stage, rapidly thinner. At these stages, the epidermis in the skin surrounding the pressed site became gradually thicker. At the yellow scar stage, the skin was covered only by necrotic tissues and horny layer. These layers were scratched during walking and turning, and the yellow scar stage became the open wound stage. Inflammatory reaction began at the thickening stage, and at the yellow scar and open wound stages, necrosis, infiltration of inflammatory cells and dilation of small blood vessels were observed. These morphological features are quite similar to those in the human pressure ulcer. These findings suggest that these dermal injuries could compare the human pressure ulcer for medical treatment and depressurization in future study. Copyright © 2016 Elsevier GmbH. All rights reserved.

Development of Bench and Full-Scale Temperature and pH Responsive Functionalized PVDF Membranes with Tunable Properties

PubMed Central

Xiao, Li; Isner, Austin; Waldrop, Krysta; Saad, Anthony; Takigawa, Doreen; Bhattacharyya, Dibakar

2014-01-01

Temperature and pH responsive polymers (poly(N-isopropylacrylamide) (PNIPAAm), and polyacrylic acid, PAA) were synthesized in one common macrofiltration PVDF membrane platform by pore-filling method. The microstructure and morphology of the PNIPAAm-PVDF, and PNIPAAm-FPAA-PVDF membranes were studied by attenuated total reflectance Fourier transform infrared (ATR-FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The membrane pore size was controlled by the swelling and shrinking of the PNIPAAm at the temperature around lower critical solution temperature (LCST). The composite membrane demonstrated a rapid and reversible swelling and deswelling change within a small temperature range. The controllable flux makes it possible to utilize this temperature responsive membrane as a valve to regulate filtration properties by temperature change. Dextran solution (Mw=2,000,000g/mol, 26 nm diameter) was used to evaluate the separation performance of the temperature responsive membranes. The ranges of dextran rejection are from 4% to 95% depending on the temperature, monomer amount and pressure. The full-scale membrane was also developed to confirm the feasibility of our bench-scale experimental results. The full-scale membrane also exhibited both temperature and pH responsivity. This system was also used for controlled nanoparticles synthesis and for dechlorination reaction. PMID:24944434

Friction of sodium alginate hydrogel scaffold fabricated by 3-D printing.

PubMed

Yang, Qian; Li, Jian; Xu, Heng; Long, Shijun; Li, Xuefeng

2017-04-01

A rapid prototyping technology, formed by three-dimensional (3-D) printing and then crosslinked by spraying Ca 2+ solution, is developed to fabricate a sodium alginate (SA) hydrogel scaffold. The porosity, swelling ratio, and compression modulus of the scaffold are investigated. A friction mechanism is developed by studying the reproducible friction behavior. Our results show that the scaffold can have 3-D structure with a porosity of 52%. The degree of swelling of the SA hydrogel scaffold is 8.5, which is nearly the same as bulk SA hydrogel. SA hydrogel exhibits better compressive resilience than bulk hydrogel despite its lower compressive modulus compared to bulk hydrogel. The SA hydrogel scaffold exhibits a higher frictional force at low sliding velocity (10 -6 to 10 -3  m/s) compared to bulk SA hydrogel, and they are equal at high sliding velocity (10 -2 to 1 m/s). For a small pressure (0.3 kPa), the SA hydrogel scaffold shows good friction reproducibility. In contrast, bulk SA hydrogel shows poor reproducibility with respect to friction behavior. The differences in friction behaviors between the SA hydrogel scaffold and bulk SA hydrogel are related to the structure of the scaffold, which can keep a stable hydrated lubrication layer.

Propagation Route and Speed of Swell in the Indian Ocean

NASA Astrophysics Data System (ADS)

Zheng, C. W.; Li, C. Y.; Pan, J.

2018-01-01

The characteristics of swell propagation play an important role in the forecasting of ocean waves as well as on research on global climate change, wave energy development, and disaster prevention and reduction. To reveal the propagation routes, terminal targets and speeds of swells that originate from the southern Indian Ocean westerly (SIOW), an intraseasonal swell index (SI) was defined based on the 45 year (September 1957 to August 2002) ERA-40 wave reanalysis data product from the European Center for Medium-Range Weather Forecasts (ECMWF). The results show that the main body of the SIOW-related swells typically spread to the waters off Sri Lanka and Christmas Island, while the branches spread to the Arabian Sea and other waters. The propagation speeds of swells originated in the SIOW were fastest in May and August, followed by November, and were slowest in February. Swells usually required 4-6 days to propagate from the western part of the SIOW to the waters off Sri Lanka and Christmas Island, whereas swells usually required 2-4 days to propagate from the eastern part of the SIOW to the waters off Christmas Island.

Self-Sealing Cementitious Materials by Using Water-Swelling Rubber Particles

PubMed Central

Lv, Leyang; Schlangen, Erik; Xing, Feng

2017-01-01

Water ingress into cracked concrete structures is a serious problem, as it can cause leakage and reinforcement corrosion and thus reduce functionality and safety of the structures. In this study, the application of water-swelling rubber particles for providing the cracked concrete a self-sealing function was developed. The feasibility of applying water-swelling rubber particles and the influence of incorporating water-swelling rubber particles on the mechanical properties of concrete was investigated. The self-sealing efficiency of water-swelling rubber particles with different content and particle size was quantified through a permeability test. The sealing effect of the water swelling rubber particles was monitored by X-ray computed tomography. The experimental results show that, by using 6% of these water swelling rubber particles as a replacement of aggregates in concrete, up to 64% and 61% decrease of water permeability was realized for 0.7 mm and 1.0 mm cracks. Furthermore, when the concrete cracks, the water swelling rubber particles can act as a crack bridging filler, preventing the crack from fully separating the specimens in two pieces. PMID:28829384

Determination of Oriented Strandboard properties from a three-dimensional density distribution using the finite element method

NASA Astrophysics Data System (ADS)

Tackie, Alan Derek Nii

Computer modeling of Oriented Strand Board (OSB) properties has gained widespread attention with numerous models created to better understand OBS behavior. Recent models allow researchers to observe multiple variables such as changes in moisture content, density and resin effects on panel performance. Thickness-swell variation influences panel durability and often has adverse effects on a structural panel's bending stiffness. The prediction of out-of-plane swell under changing moisture conditions was, therefore, the essence for developing a model in this research. The finite element model accounted for both vertical and horizontal density variations, the three-dimensional (3D) density variation of the board. The density variation, resulting from manufacturing processes, affects the uniformity of thickness-swell in OSB and is often exacerbated by continuous sorption of moisture that leads to potentially damaging internal stresses in the panel. The overall thickness-swell (the cumulative swell from non-uniform horizontal density profile, panel swell from free water, and spring-back from panel compression) was addressed through the finite element model in this research. The pursued goals in this study were, first and foremost, the development of a robust and comprehensive finite element model which integrated several component studies to investigate the effects of moisture variation on the out-of-plane thickness-swell of OSB panels, and second, the extension of the developed model to predict panel stiffness. It is hoped that this paper will encourage researchers to adopt the 3D density distribution approach as a viable approach to analyzing the physical and mechanical properties of OSB.

* Constrained Cage Culture Improves Engineered Cartilage Functional Properties by Enhancing Collagen Network Stability.

PubMed

Nims, Robert J; Cigan, Alexander D; Durney, Krista M; Jones, Brian K; O'Neill, John D; Law, Wing-Sum A; Vunjak-Novakovic, Gordana; Hung, Clark T; Ateshian, Gerard A

2017-08-01

When cultured with sufficient nutrient supply, engineered cartilage synthesizes proteoglycans rapidly, producing an osmotic swelling pressure that destabilizes immature collagen and prevents the development of a robust collagen framework, a hallmark of native cartilage. We hypothesized that mechanically constraining the proteoglycan-induced tissue swelling would enhance construct functional properties through the development of a more stable collagen framework. To test this hypothesis, we developed a novel "cage" growth system to mechanically prevent tissue constructs from swelling while ensuring adequate nutrient supply to the growing construct. The effectiveness of constrained culture was examined by testing constructs embedded within two different scaffolds: agarose and cartilage-derived matrix hydrogel (CDMH). Constructs were seeded with immature bovine chondrocytes and cultured under free swelling (FS) conditions for 14 days with transforming growth factor-β before being placed into a constraining cage for the remainder of culture. Controls were cultured under FS conditions throughout. Agarose constructs cultured in cages did not expand after the day 14 caging while FS constructs expanded to 8 × their day 0 weight after 112 days of culture. In addition to the physical differences in growth, by day 56, caged constructs had higher equilibrium (agarose: 639 ± 179 kPa and CDMH: 608 ± 257 kPa) and dynamic compressive moduli (agarose: 3.4 ± 1.0 MPa and CDMH 2.8 ± 1.0 MPa) than FS constructs (agarose: 193 ± 74 kPa and 1.1 ± 0.5 MPa and CDMH: 317 ± 93 kPa and 1.8 ± 1.0 MPa for equilibrium and dynamic properties, respectively). Interestingly, when normalized to final day wet weight, cage and FS constructs did not exhibit differences in proteoglycan or collagen content. However, caged culture enhanced collagen maturation through the increased formation of pyridinoline crosslinks and improved collagen matrix stability as measured by α-chymotrypsin solubility. These findings demonstrate that physically constrained culture of engineered cartilage constructs improves functional properties through improved collagen network maturity and stability. We anticipate that constrained culture may benefit other reported engineered cartilage systems that exhibit a mismatch in proteoglycan and collagen synthesis.

Concurrent changes in aggregation and swelling of coal particles in solvents

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

Nishioka, M.

1995-12-31

A new method of coal swelling has been developed tinder the condition of low coal concentrations with continuous mixing of coal and solvent. The change in particle size distributions by a laser scattering procedure was used for the evaluation of coal swelling. Particle size distributions in good and poor solvents were nearly equal, but reversibly changed in good solvents from time to time. The effects of solubles and coal concentrations on the distributions were small. It was concluded that aggregate d coal particles disaggregate in good solvents, and that an increase in the particle size distribution due to swelling inmore » good solvents are compensated by a decrease in the particle size due to disaggregation. Therefore, the behavior of coal particles in solvents is controlled by aggregation in addition to coal swelling. This implies that an increase in the particle size due to coal swelling in actual processes is not so large as expected by the results obtained from the conventional coal swelling methods.« less

A dual-core double emulsion platform for osmolarity-controlled microreactor triggered by coalescence of encapsulated droplets.

PubMed

Guan, Xuewei; Hou, Likai; Ren, Yukun; Deng, Xiaokang; Lang, Qi; Jia, Yankai; Hu, Qingming; Tao, Ye; Liu, Jiangwei; Jiang, Hongyuan

2016-05-01

Droplet-based microfluidics has provided a means to generate multi-core double emulsions, which are versatile platforms for microreactors in materials science, synthetic biology, and chemical engineering. To provide new opportunities for double emulsion platforms, here, we report a glass capillary microfluidic approach to first fabricate osmolarity-responsive Water-in-Oil-in-Water (W/O/W) double emulsion containing two different inner droplets/cores and to then trigger the coalescence between the encapsulated droplets precisely. To achieve this, we independently control the swelling speed and size of each droplet in the dual-core double emulsion by controlling the osmotic pressure between the inner droplets and the collection solutions. When the inner two droplets in one W/O/W double emulsion swell to the same size and reach the instability of the oil film interface between the inner droplets, core-coalescence happens and this coalescence process can be controlled precisely. This microfluidic methodology enables the generation of highly monodisperse dual-core double emulsions and the osmolarity-controlled swelling behavior provides new stimuli to trigger the coalescence between the encapsulated droplets. Such swelling-caused core-coalescence behavior in dual-core double emulsion establishes a novel microreactor for nanoliter-scale reactions, which can protect reaction materials and products from being contaminated or released.

A dual-core double emulsion platform for osmolarity-controlled microreactor triggered by coalescence of encapsulated droplets

PubMed Central

Guan, Xuewei; Hou, Likai; Ren, Yukun; Deng, Xiaokang; Lang, Qi; Jia, Yankai; Hu, Qingming; Tao, Ye; Liu, Jiangwei; Jiang, Hongyuan

2016-01-01

Droplet-based microfluidics has provided a means to generate multi-core double emulsions, which are versatile platforms for microreactors in materials science, synthetic biology, and chemical engineering. To provide new opportunities for double emulsion platforms, here, we report a glass capillary microfluidic approach to first fabricate osmolarity-responsive Water-in-Oil-in-Water (W/O/W) double emulsion containing two different inner droplets/cores and to then trigger the coalescence between the encapsulated droplets precisely. To achieve this, we independently control the swelling speed and size of each droplet in the dual-core double emulsion by controlling the osmotic pressure between the inner droplets and the collection solutions. When the inner two droplets in one W/O/W double emulsion swell to the same size and reach the instability of the oil film interface between the inner droplets, core-coalescence happens and this coalescence process can be controlled precisely. This microfluidic methodology enables the generation of highly monodisperse dual-core double emulsions and the osmolarity-controlled swelling behavior provides new stimuli to trigger the coalescence between the encapsulated droplets. Such swelling-caused core-coalescence behavior in dual-core double emulsion establishes a novel microreactor for nanoliter-scale reactions, which can protect reaction materials and products from being contaminated or released. PMID:27279935

Enhancement of gravimetric forced flow through system to determine sorption, swelling, and mass transfer characteristics of liquid sorbents

NASA Astrophysics Data System (ADS)

Dresp, G.; Petermann, M.; Fieback, T. M.

2018-04-01

An existing apparatus for forced flow through of liquid sorbents has been enhanced with an optically accessible system including a transparent crucible, high pressure viewing cell, and camera. With this optical system, the active surface area between gas and liquid can be determined in situ for the first time under industrial process conditions while maintaining the accuracy of a magnetic suspension balance. Additionally, occurring swelling and the resulting buoyancy changes can now be corrected, further improving the quality of the data. Validation measurements focusing on the sorption isotherms, swelling, and bubble geometry of 1-butyl-3-methylimidazolium tetrafluoroborate with nitrogen at 303 K and up to 17 MPa, as well as with carbon dioxide at 303 K, 323 K, and 373 K at up to 3.5 MPa were completed. Absorption of nitrogen resulted in no observable volume change, whereas absorption of carbon dioxide resulted in temperature independent swelling of up to 9.8%. The gas bubble's structure and behavior during its ascend through the liquid was optically tracked in situ. Combining these two data sets with the absorption kinetics forms the basis to determine the measuring system independent mass transfer coefficients, which are applicable in other laboratory scale and industrial processes.

Tuning, Validation, and Uncertainty Estimates for a Sound Exposure Model

DTIC Science & Technology

2011-09-01

to swell height. This phenomenon is described in ―Observations of Fluctuation of Transmitted Sound in Shallow Water‖ ( Urick 1969). Mean wave...newport/usrdiv/Transducers/G34.pdf] 40 Saunders, P. M., 1981: Practical Conversion of Pressure to Depth. J. Phys. Oceanogr., 11, 573–574. Urick , R

Pressure induced swelling in microporous materials

DOEpatents

Vogt, Thomas; Hriljac, Joseph A.; Lee, Yongjae

2006-07-11

A method for capturing specified materials which includes contacting a microporous material with a hydrostatic fluid having at least one specified material carried therein, under pressure which structurally distorts the lattice sufficiently to permit entry of the at least one specified material. The microporous material is capable of undergoing a temporary structural distortion which alters resting lattice dimensions under increased ambient pressure and at least partially returning to rest lattice dimensions when returned to ambient pressure. The pressure of the fluid is then reduced to permit return to at least partial resting lattice dimension while the at least one specified material is therein. By this method, at least one specified material is captured in the microporous material to form a modified microporous material.

Transmission seal development

NASA Technical Reports Server (NTRS)

Brien, M.

1977-01-01

An experimental evaluation was performed on a high-speed (72.9 m/s, 14,349 ft/min) transmission seal of the synergistic type. During testing of the seal, oil leakage occurred at positive bearing cavity pressures. Modifications were made in an attempt to eliminate the leakage but none were completely successful. Leakage appears to be the result of questionable positioning of the sealing elements resulting in inadequate shaft contact by the oil side sealing element. This condition may be related to the nonsymmetrical shape of the elastomeric retainer and to dimensional changes caused by swelling of the elastomeric retainer from exposure to the sealed fluid. Indications of a speed dependent leakage characteristic were also observed.

Etanercept Injection

MedlinePlus

... own joints, causing pain, swelling, and loss of function) in adults, psoriatic arthritis (condition that causes joint ... its own joints, causing pain, swelling, loss of function, and delays in growth and development) in children ...

Conceptual design of a device to measure hand swelling in a micro-gravity environment

NASA Technical Reports Server (NTRS)

Hysinger, Christopher L.

1993-01-01

In the design of pressurized suits for use by astronauts in space, proper fit is an important consideration. One particularly difficult aspect of the suit design is the design of the gloves. If the gloves of the suit do not fit properly, the grip strength of the astronaut can be decreased by as much as fifty percent. These gloves are designed using an iterative process and can cost over 1.5 million dollars. Glove design is further complicated by the way the body behaves in a micro-gravity environment. In a micro-gravity setting, fluid from the lower body tends to move into the upper body. Some of this fluid collects in the hands and causes the hands to swell. Therefore, a pair of gloves that fit well on earth may not fit well when they are used in space. The conceptual design process for a device which can measure the swelling that occurs in the hands in a micro-gravity environment is described. This process involves developing a specifications list and function structure for the device and generating solution variants for each of the sub functions. The solution variants are then filtered, with the variants that violate any of the specifications being discarded. After acceptable solution variants are obtained, they are combined to form design concepts. These design concepts are evaluated against a set of criteria and the design concepts are ranked in order of preference. Through this process, the two most plausible design concepts were an ultrasonic imaging technique and a laser mapping technique. Both of these methods create a three dimensional model of the hand, from which the amount of swelling can be determined. In order to determine which of the two solutions will actually work best, a further analysis will need to be performed.

Effect of grain morphology on gas bubble swelling in UMo fuels – A 3D microstructure dependent Booth model

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

Hu, Shenyang; Burkes, Douglas; Lavender, Curt A.

2016-11-01

A three dimensional microstructure dependent swelling model is developed for studying the fission gas swelling kinetics in irradiated nuclear fuels. The model is extended from the Booth model [1] in order to investigate the effect of heterogeneous microstructures on gas bubble swelling kinetics. As an application of the model, the effect of grain morphology, fission gas diffusivity, and spatial dependent fission rate on swelling kinetics are simulated in UMo fuels. It is found that the decrease of grain size, the increase of grain aspect ratio for the grain having the same volume, and the increase of fission gas diffusivity (fissionmore » rate) cause the increase of swelling kinetics. Other heterogeneities such as second phases and spatial dependent thermodynamic properties including diffusivity of fission gas, sink and source strength of defects could be naturally integrated into the model to enhance the model capability.« less

The wind sea and swell waves climate in the Nordic seas

NASA Astrophysics Data System (ADS)

Semedo, Alvaro; Vettor, Roberto; Breivik, Øyvind; Sterl, Andreas; Reistad, Magnar; Soares, Carlos Guedes; Lima, Daniela

2015-02-01

A detailed climatology of wind sea and swell waves in the Nordic Seas (North Sea, Norwegian Sea, and Barents Sea), based on the high-resolution reanalysis NORA10, developed by the Norwegian Meteorological Institute, is presented. The higher resolution of the wind forcing fields, and the wave model (10 km in both cases), along with the inclusion of the bottom effect, allowed a better description of the wind sea and swell features, compared to previous global studies. The spatial patterns of the swell-dominated regional wave fields are shown to be different from the open ocean, due to coastal geometry, fetch dimensions, and island sheltering. Nevertheless, swell waves are still more prevalent and carry more energy in the Nordic Seas, with the exception of the North Sea. The influence of the North Atlantic Oscillation on the winter regional wind sea and swell patterns is also presented. The analysis of the decadal trends of wind sea and swell heights during the NORA10 period (1958-2001) shows that the long-term trends of the total significant wave height (SWH) in the Nordic Seas are mostly due to swell and to the wave propagation effect.

Evaluation on expansive performance of the expansive soil using electrical responses

NASA Astrophysics Data System (ADS)

Chu, Ya; Liu, Songyu; Bate, Bate; Xu, Lei

2018-01-01

Light structures, such as highways and railroads, built on expansive soils are prone to damages from the swelling of their underlain soil layers. Considerable amount of research has been conducted to characterize the swelling properties of expansive soils. Current swell characterization models, however, are limited by lack of standardized tests. Electrical methods are non-destructive, and are faster and less expensive than the traditional geotechnical methods. Therefore, geo-electrical methods are attractive for defining soil characteristics, including the swelling behavior. In this study, comprehensive laboratory experiments were undertaken to measure the free swelling and electrical resistivity of the mixtures of commercial kaolinite and bentonite. The electrical conductivity of kaolinite-bentonite mixtures was measured by a self-developed four-electrode soil resistivity box. Increasing the free swelling rate of the kaolinite-bentonite mixtures (0.72 to 1 of porosity of soils samples) led to a reduction in the electrical resistivity and an increase in conductivity. A unique relationship between free swelling rate and normalized surface conductivity was constructed for expensive soils by eliminating influences of porosity and m exponent. Therefore, electrical response measurement can be used to characterize the free swelling rate of expensive soils.

Africa's Megafans and Their Tectonic Setting

NASA Technical Reports Server (NTRS)

Wilkinson, M. J.; Burke, K.

2016-01-01

Megafans are a really extensive continental sediment bodies, fluvially derived, and fan-shaped in planform. Only those >80 km long were included in this study. Africa's megafans were mapped for purposes of both comprehensive geomorphic description and as a method of mapping by remote sensing large probable fluvial sediment bodies (we exclude sediment bodies deposited in well defined, modern floodplains and coastal deltas). Our criteria included a length dimension of >80 km and maximum width >40 km, partial cone morphology, and a radial drainage pattern. Visible and especially IR imagery were used to identify the features, combined with topographic SRTM data. We identified 99 megafans most of which are unstudied thus far. Their feeder rivers responsible for depositing megafan sediments rise on, and are consequent drainages oriented down the slopes of the swells that have dominated African landscapes since approximately 34 Ma (the high points in Africa's so-called basin-and-swell topography [1]). Most megafans (66%) have developed along these consequent rivers relatively near the swell cores, oriented radially away from the swells. The vast basins between the swells provide accommodation for megafan sediment wedges. Although clearly visible remotely, most megafans are inactive as a result of incision by the feeder river (which then no longer operates on the fan surface). Two tectonic settings control the location of Africa's megafans, 66% on swell flanks, and 33% related to rifts. (i) Swell flanks Most megafans are apexed relatively near the core of the parent swell, and are often clustered in groups: e.g., six on the west and north flanks of the Hoggar Swell (Algeria), seven on the north and south flanks of the Tibesti Swell (Libya-Chad borderlands), twelve on the west flank of the Ethiopian Swell, four on the east flank of the East African Swell (Kenya), Africa's largest, and eight around Angola's Bié Swell (western Zambia, northern Namibia). A cluster of possible fans lies on the western margin of the Congo Basin (Mayombe Swell), and on the coastal slopes of the Namibia Swell. Sheer size may have militated aginst the recognition of many megafans: the largest in the Sahara are the Teghahart (378 km, Hoggar Swell, Algeria), and the Wadi Albalata (340 km, Uweinat Swell, Egypt). In southern Africa the largest are the Cubango (320 km, Bié Swell, Angola/ Namibia), and the Limpopo (230 km, Mozambique). (ii) Rift zones (a) Steer's horns basins-wide depressions centered on rifts. The largest contiguous group (n=14) developed in a steer's-horns basin occupies the wide Muglad depression (200-350 km, South Sudan). Four rift-related megafans lie SE of Lake Chad (Chad). Nine megafans occupy the complex Anza Rift in Kenya/South Somalia. The Salamat megafan (Chad), is unusual because it oriented parallel with the linked Salamat, Doseo and Doba rift axes, and is consequently one of the longest in Africa (465 km). (b) Rift depressions sensu stricto. Most rifts are too narrow to provide a transverse dimension large enough to accommodate megafans. Although well-known, the Okavango Rift (NW Botswana, NE Namibia) is unique in Africa in hosting three megafans within identifiable faulted margins. The Nile megafan is Africa's largest (476 km) and comprises the vast Sudd wetland (South Sudan). An explanation for its remarkable size may be its location in a depression at the junction of two conducive tectonic zones, the East African Swell margin and the Muglad steer's-horns depression. Discharge of the River Nile, the largest in the region, has allowed the Nile megafan to outcompete neighboring megafans for space.

Development and Characterization of UHMWPE Fiber-Reinforced Hydrogels For Meniscal Replacement

NASA Astrophysics Data System (ADS)

Holloway, Julianne Leigh

Meniscal tears are the most common orthopedic injuries to the human body. The current treatment of choice, however, is a partial meniscectomy that leads to osteoarthritis proportional to the amount of tissue removed. As a result, there is a significant clinical need to develop materials capable of restoring the biomechanical contact stress distribution to the knee after meniscectomy and preventing the onset of osteoarthritis. In this work, a fiber-reinforced hydrogel-based synthetic meniscus was developed that allows for tailoring of the mechanical properties and molding of the implant to match the size, shape, and property distribution of the native tissue. Physically cross-linked poly(vinyl alcohol) (PVA) hydrogels were reinforced with ultrahigh molecular weight polyethylene (UHMWPE) fibers and characterized in compression (0.1-0.8 MPa) and tension (0.1-250 MPa) showing fine control over mechanical properties within the range of the human meniscus. Morphology and crystallinity analysis of PVA hydrogels showed increases in crystallinity and PVA densification, or phase separation, with freeze-thaw cycles. A comparison of freeze-thawed and aged, physically cross-linked hydrogels provided insight on both crystallinity and phase separation as mechanisms for PVA gelation. Results indicated both mechanisms independently contributed to hydrogel modulus for freeze-thawed hydrogels. In vitro swelling studies were performed using osmotic solutions to replicate the swelling pressure present in the knee. Minimal swelling was observed for hydrogels with a PVA concentration of 30-35 wt%, independently of hydrogel freeze-thaw cycles. This allows for independent tailoring of hydrogel modulus and pore structure using freeze-thaw cycles and swelling behavior using polymer concentration to match a wide range of properties needed for various soft tissue applications. The UHMWPE-PVA interface was identified as a significant weakness. To improve interfacial adhesion, a novel biocompatible PVA grafting technique was developed to form a direct covalent linkage at the fiber-matrix interface. Chemical grafting was tailored as a function of the number of sites available for covalent bonding and the percentage of sites reacted. PVA grafting resulted in significant improvements to interfacial shear strength from 11 kPa without any treatment to above 220 kPa following grafting. After grafting, failure was observed cohesively within the PVA hydrogel indicating the UHMWPE-PVA interface was successfully optimized. Lastly, in vitro gait simulations and an in vivo sheep study demonstrated the feasibility and biocompatibility of the proposed UHMWPE-PVA composite. The results from this work can be applied to designing materials for other soft tissue applications, including the anterior cruciate ligament (ACL) and the annulus fibrosus.

Sustaining the Human Spirit of the High School Principal Leading for Equity

ERIC Educational Resources Information Center

Richardson, Ryan David

2017-01-01

Shrinking budgets and swelling public accountability characterize public education in the 21st century. Pressures to increase achievement while assuring the emotional and physical safety of all students make the work of the secondary principal daunting. A leader for equity must be a symbolic, visionary, and instructional leader that creates…

Xiphoid syndrome: an uncommon occupational disorder.

PubMed

Yapici Ugurlar, O; Ugurlar, M; Ozel, A; Erturk, S M

2014-01-01

We report a case of a 45-year-old man, complaining of swelling and pain in his epigastric region for the last 3 years. According to his medical history, he had undergone various investigations and treatments for gastro-oesophageal reflux, without relief. He had had a history of chronic repeated microtraumas to his sternum during 9 years of working as a carpenter, as a result of placing wood against his anterior chest wall and pushing the former into a plank cutting machine. On examination, a tender swelling was palpable as an immobile, hard mass showing minimal protrusion under the skin on the xiphoid process. He was diagnosed as having xiphoid syndrome. We prescribed anti-inflammatory medication and advised him to avoid pressure on his anterior chest wall, especially on the sternum, while cutting wood. At follow-up, the symptoms were relieved. Xiphoid syndrome may be seen in people performing hard physical work who incur sustained pressure or friction on their anterior chest wall. The case emphasizes the importance of the occupational history as well as clinical and radiological investigation of unusual conditions as mentioned above.

Effects of pressure on morphology and structure of bio-char from pressurized entrained-flow pyrolysis of microalgae.

PubMed

Maliutina, Kristina; Tahmasebi, Arash; Yu, Jianglong

2018-06-01

The present dataset describes the entrained-flow pyrolysis of Microalgae Chlorella vulgaris and the results obtained during bio-char characterization. The dataset includes a brief explanation of the experimental procedure, experimental conditions and the influence of pyrolysis conditions on bio-chars morphology and carbon structure. The data show an increase in sphericity and surface smoothness of bio-chars at higher pressures and temperatures. Data confirmed that the swelling ratio of bio-chars increased with pressure up to 2.0 MPa. Consequently, changes in carbon structure of bio-chars were investigated using Raman spectroscopy. The data showed the increase in carbon order of chars at elevated pressures. Changes in the chemical structure of bio-char as a function of pyrolysis conditions were investigated using FTIR analysis.

Effect of the crystal chemistry on the hydration mechanism of swelling micas

NASA Astrophysics Data System (ADS)

Pavón, Esperanza; Alba, María D.; Castro, Miguel A.; Cota, A.; Osuna, Francisco J.; Pazos, M. Carolina

2017-11-01

Swelling and dehydration under minor changes in temperature and water vapor pressure is an important property that clays and clay minerals exhibit. In particular, their interlayer space, the solid-water interface and the layers' collapse and re-expansion have received much attention because it affects to the dynamical properties of interlayer cations and thus the transfer and fate of water and pollutants. In this contribution, the dehydration and rehydration mechanism of a swelling high-charge mica family is examined by in situ X-ray Diffraction. The effect of the aluminosilicate layer charge and the physicochemical properties of the interlayer cations on these processes are analyzed. The results showed that the dehydration temperature and the number of steps involved in this process are related to the layer charge of the silicate and the physicochemical properties of the interlayer cations. Moreover, the ability to adsorb water molecules in a confined space with high electric field by the interlayer cations does not only depend on their hydration enthalpy but also on the electrostatic parameters of these cations.

Monitoring austral and cyclonic swells in the "Iles Eparses" (Mozambique channel) from microseismic noise

NASA Astrophysics Data System (ADS)

Barruol, Guilhem; Davy, Céline; Fontaine, Fabrice R.; Schlindwein, V.; Sigloch, K.

2016-04-01

We deployed five broadband three-components seismic stations in the Iles Eparses in the south-west Indian Ocean and on Mayotte Island, between April 2011 and January 2014. These small and remote oceanic islands suffer the effects of strong ocean swells that affect their coastal environments but most islands are not instrumented by wave gauges to characterize the swells. However, wave action on the coast causes high levels of ground vibrations in the solid earth, so-called microseismic noise. We use this link between the solid earth and ocean wave activity to quantify the swells locally. Spectral analyses of the continuous seismic data show clear peaks in the 0.05-0.10 Hz frequency band (periods between 10 and 20 s), corresponding to the ocean wave periods of the local swells. We analyze an example of austral swell occurring in August 2013 and a cyclonic event (Felleng) that developed in January 2013, and quantify the ground motion at each station induced by these events. In both cases, we find a linear polarization in the horizontal plane with microseismic amplitude directly correlated to the swell height (as predicted by the global swell model WaveWatchIII), and a direction of polarization close to the predicted swell propagation direction. Although this analysis has not been performed in real time, it demonstrates that terrestrial seismic stations can be efficiently used as wave gauges, and are particularly well suited for quantifying extreme swell events. This approach may therefore provide useful and cheaper alternatives to wave buoys for monitoring swells and the related environmental processes such as beach erosion or coral reef damages.

Polyelectrolyte polymer properties in relation to male contraceptive RISUG action.

PubMed

Roy, Sohini; Ghosh, Debidas; Guha, Sujoy K

2009-02-15

RISUG a polyelectrolytic hydrogel (styrene maleic anhydride and dimethyl sulfoxide) has proven to be efficacious as a contraceptive for a long term when injected into the lumen of vas deferens. Currently it is in advanced phase III clinical trials in India. Present investigation analyzes the swelling characteristics of RISUG hydrogel in different pH buffers and various biological fluids to understand its retention in the vas deferens as reported in previous studies. Significant variation in degree of swelling and equilibrium swelling ratio with transformation of Fickian to non-Fickian mode of diffusion was observed with increased pH. This might be due to ionization of carboxylic groups at high pH resulting in increased electrostatic repulsive force and high osmotic pressure inside the hydrogel network affecting its physical cross-linking and increases the free volume. Conversely, at low pH the dissociation of carboxylic group is limited making the hydrogel more stable. Interaction with various biomolecules present in various biological fluids was also studied. SEM, AFM and FTIR were used to analyze the topological and structural parameters of the polymer in different mediums. Loosening of structure and increasing porosity with significant adsorption of various biomolecules was observed. AFM revealed a significant change in overall roughness of polymer surface on interaction with different biological fluids. These observations suggest that the swelling and increased roughness will lead to increased resistance to sperm movement in the vas deferens.

Hydrogel-forming microneedles increase in volume during swelling in skin, but skin barrier function recovery is unaffected

PubMed Central

Donnelly, Ryan F.; Mooney, Karen; McCrudden, Maelíosa T.C.; Vicente-Pérez, Eva M.; Belaid, Luc; González-Vázquez, Patricia; McElnay, James C.; Woolfson, A. David

2014-01-01

We describe, for the first time, quantification of in-skin swelling and fluid uptake by hydrogel-forming microneedle arrays (MN) and skin barrier recovery in human volunteers. Such MN, prepared from aqueous blends of hydrolysed poly(methylvinylether/maleicanhydride) (15% w/w) and the crosslinker poly(ethyleneglycol) 10,000 daltons (7.5% w/w), were inserted into the skin of human volunteers (n = 15) to depths of approximately 300 μm by gentle hand pressure. The MN swelled in skin, taking up skin interstitial fluid, such that their mass had increased by approximately 30% after 6 hours in skin. Importantly, however, skin barrier function recovered within 24 hours post microneedle removal, regardless of how long the MN had been in skin or how much their volume had increased with swelling. Further research on closure of MN-induced micropores is required, since transepidermal water loss measurements suggested micropore closure, while optical coherence tomography indicated that MN-induced micropores had not closed over, even 24 hours after MN had been removed. There were no complaints of skin reactions, adverse events or strong views against MN use by any of the volunteers. Only some minor erythema was noted after patch removal, although this always resolved within 48 hours and no adverse events were present on follow-up. PMID:24633895

Thyroid swellings in the art of the Italian Renaissance.

PubMed

Sterpetti, Antonio V; De Toma, Giorgio; De Cesare, Alessandro

2015-09-01

Thyroid swellings in the art of the Italian Renaissance are sporadically reported in the medical literature. Six hundred paintings and sculptures from the Italian Renaissance, randomly selected, were analyzed to determine the prevalence of personages with thyroid swellings and its meaning. The prevalence of personages with thyroid swellings in the art of Italian Renaissance is much higher than previously thought. This phenomenon was probably secondary to iodine deficiency. The presence of personages with thyroid swelling was related to specific meanings the artists wanted to show in their works. Even if the function and the role of the thyroid were discovered only after thyroidectomy was started to be performed, at the beginning of the 19th century, artists of the Italian Renaissance had the intuition that thyroid swellings were related to specific psychological conditions. Artistic intuition and sensibility often comes before scientific demonstration, and it should be a guide for science development. Copyright © 2015 Elsevier Inc. All rights reserved.

Intraoperative Tumoral Bleeding of Hypervascular Medulloblastoma after Ventricular Drainage: A Case Report.

PubMed

Ryu, Han-Seung; Jung, Tae-Young; Han, Moon-Soo; Kim, Seul-Ki; Lee, Kyung-Hwa

2017-01-01

We report a rare case of intraoperative tumoral bleeding of a hypervascular medulloblastoma. A 12-year-old girl presented with dizziness and nausea. Brain magnetic resonance (MR) images revealed an approximately 4.2-cm enhanced mass on the cerebellar vermis associated with mild perilesional edema and increased cerebral blood volume. Angiography showed tumoral staining and developed occipital and circular dural sinuses in the venous phase. A suboccipital craniotomy was performed. To relieve the intracranial pressure, cerebrospinal fluid (CSF) was drained via a lateral ventricular catheter in the occipital horn. During the opening of the dura, the brain swelling had progressed, and brain computed tomography revealed an intratumoral hemorrhage with brainstem compression. The patient was in a stuporous mental state. A reoperation was performed, and the mass was totally removed. The pathologic findings revealed a medulloblastoma with abnormal enlarged arterial vascular structures. Postoperatively, the patient recovered to an alert mental state. She underwent chemotherapy and radiotherapy. There was no recurrence after 1 year. Pre-resectional CSF drainage should not be routinely performed in posterior fossa tumors, especially with increased cerebral blood volume on MR perfusion images. Complete removal should be performed quickly while CSF drainage should be performed slowly. An intratumoral hemorrhage should be considered in posterior fossa tumors when severe brain swelling suddenly develops after CSF drainage. © 2016 S. Karger AG, Basel.

Coupled THMC models for bentonite in clay repository for nuclear waste

NASA Astrophysics Data System (ADS)

Zheng, L.; Rutqvist, J.; Birkholzer, J. T.; Li, Y.; Anguiano, H. H.

2015-12-01

Illitization, the transformation of smectite to illite, could compromise some beneficiary features of an engineered barrier system (EBS) that is composed primarily of bentonite and clay host rock. It is a major determining factor to establish the maximum design temperature of the repositories because it is believed that illitization could be greatly enhanced at temperatures higher than 100 oC and thus significantly lower the sorption and swelling capacity of bentonite and clay rock. However, existing experimental and modeling studies on the occurrence of illitization and related performance impacts are not conclusive, in part because the relevant couplings between the thermal, hydrological, chemical, and mechanical (THMC) processes have not been fully represented in the models. Here we present fully coupled THMC simulations of a generic nuclear waste repository in a clay formation with bentonite-backfilled EBS. Two scenarios were simulated for comparison: a case in which the temperature in the bentonite near the waste canister can reach about 200 oC and a case in which the temperature in the bentonite near the waste canister peaks at about 100 oC. The model simulations demonstrate that illitization is in general more significant at higher temperatures. We also compared the chemical changes and the resulting swelling stress change for two types of bentonite: Kunigel-VI and FEBEX bentonite. Higher temperatures also lead to much higher stress in the near field, caused by thermal pressurization and vapor pressure buildup in the EBS bentonite and clay host rock. Chemical changes lead to a reduction in swelling stress, which is more pronounced for Kunigel-VI bentonite than for FEBEX bentonite.

Dimensional Changes of Tracheids during Drying of Radiata Pine (Pinus radiata D. Don) Compression Woods: A Study Using Variable-Pressure Scanning Electron Microscopy (VP-SEM)

PubMed Central

Zhang, Miao; Smith, Bronwen G.; McArdle, Brian H.; Chavan, Ramesh R.; James, Bryony J.

2018-01-01

Variable-pressure scanning electron microscopy was used to investigate the dimensional changes in longitudinal, tangential and radial directions, on wetting and drying, of tracheids of opposite wood (OW) and three grades of compression woods (CWs), including severe CW (SCW) and two grades of mild compression wood (MCW) (MCW1 and MCW2) in corewood of radiata pine (Pinus radiata) saplings. The CW was formed on the underside and OW on the upper side of slightly tilted stems. In the longitudinal direction, the shrinkage of SCW tracheids was ~300% greater than that of OW tracheids, with the shrinkage of the MCW1 and MCW2 tracheids being intermediate. Longitudinal swelling was also investigated and hysteresis was demonstrated for the tracheids of all corewood types, with the extent of hysteresis increasing with CW severity. A statistical association was found between longitudinal shrinkage and the content of lignin and galactosyl residues in the cell-wall matrix. The galactosyl residues are present mostly as (1→4)-β-galactans, which are known to have a high capacity for binding water and swell on hydration. The small proportions of (1→3)-β-glucans in the CWs have similar properties. These polysaccharides may play a functional role in the longitudinal shrinking and swelling of CW tracheids. Tangential shrinkage of tracheids was greater than radial shrinkage but both were greatest for OW and least for SCW, with the MCW1 and MCW2 being intermediate. PMID:29495536

Development of acute parotitis after non-invasive ventilation

PubMed Central

Martinez, Eduardo

2017-01-01

A 90-year-old woman underwent laparoscopic exploratory laparotomy for evaluation of suspected mesenteric ischemia. She was promptly extubated postoperatively and transferred to the intensive care unit, where on the first postoperative day she developed hypoxemia necessitating initiation of noninvasive ventilation (NIV) with bilevel positive airway pressure (BiPAP). After 8 hours of BiPAP, she was noted to have swelling, erythema and tenderness in the right preauricular area. Ultrasound evaluation demonstrated an enlarged right parotid gland. With discontinuation of BiPAP and supportive measures, parotitis resolved within 6 days. The mechanism of NIV-induced acute parotitis likely involves transmission of positive pressure to the oral cavity, causing obstruction to salivary flow within the parotid (Stensen) duct. Conditions that increase salivary viscosity and promote salivary stasis, such as advanced age, dehydration, and absence of salivary gland stimulation due to restriction of oral intake, may render patients more susceptible to this complication. As NIV will continue to be a commonly-used modality for the treatment of acute respiratory failure, clinicians should be aware of this phenomenon. PMID:28840025

Sulfur removal and comminution of carbonaceous material

DOEpatents

Narain, Nand K.; Ruether, John A.; Smith, Dennis N.

1988-01-01

Finely divided, clean coal or other carbonaceous material is provided by forming a slurry of coarse coal in aqueous alkali solution and heating the slurry under pressure to above the critical conditions of steam. The supercritical fluid penetrates and is trapped in the porosity of the coal as it swells in a thermoplastic condition at elevated temperature. By a sudden, explosive release of pressure the coal is fractured into finely divided particles with release of sulfur-containing gases and minerals. The finely divided coal is recovered from the minerals for use as a clean coal product.

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

Szlufarska, Izabela; Voyles, Paul; Sridharan, Kumar

Silicon carbide is a promising cladding material because of its high strength and relatively good corrosion resistance. However, SiC is brittle and therefore SiC-based components need to be carefully designed to avoid cracking and failure by fracture. In design of SiC-based composites for nuclear reactor applications it is essential to take into account how mechanical properties are affected by radiation and temperature, or in other words, what strains and stresses develop in this material due to environmental conditions. While thermal strains in SiC can be predicted using classical theories, radiation-induced strains are much less understood. In particular, it is criticalmore » to correctly account for radiation swelling and radiation creep, which contribute significantly to dimensional instability of SiC under radiation. Swelling typically increases logarithmically with radiation dose and saturates at relatively low doses (damage levels of a few dpa). Consequently, swelling-induced stresses are likely to develop within a few months of operation of a reactor. Radiation-induced volume swelling in SiC can be as high as 2%, which is significantly higher than the cracking strain of 0.1% in SiC. Swelling-induced strains will lead to enormous stresses and fracture, unless these stresses can be relaxed via some other mechanism. An effective way to achieve stress relaxation is via radiation creep. Although it has been hypothesized that both radiation swelling and radiation creep are driven by formation of defect clusters, existing models for swelling and creep in SiC are limited by the lack of understanding of specific defects that form due to radiation in the range of temperatures relevant to fuel cladding in light water reactors (LWRs) (<1000°C). For example, defects that can be detected with traditional transmission electron microscopy (TEM) techniques account only for 10-45% of the swelling measured in irradiated SiC. Here, we have undertaken an integrated experimental and modeling effort to discover the previously invisible defects in irradiated SiC and to determine the contributions of these defects to radiation swelling. Knowledge of the most stable defect structures and the rate controlling processes during defect evolution is essential for development of predictive models for swelling and creep as a function of temperature and radiation dose. This research has been enabled by state-of-the-art imaging techniques, such as the aberration corrected scanning transmission electron microscopy (STEM) (FEI TITAN) closely coupled with multi-scale models of stable defect clusters and their evolution.« less

Dimensional stability of flakeboards as affected by board specific gravity and flake alignment

Treesearch

Robert L. Geimer

1982-01-01

The objective was to determine the relationship between the variables specific gravity (SG) and flake alignment and the dimensional stability properties of flakeboard. Boards manufactured without a density gradient were exposed to various levels of relative humidity and a vacuum-pressure soak (VPS) treatment. Changes in moisture content (MC), thickness swelling, and...

Resin impregnation of cellulose nanofibril films facilitated by water swelling

Treesearch

Yan Qing; Ronald Sabo; Zhiyong Cai; Yiqiang Wu

2013-01-01

Flexible composite films were produced by impregnating aqueous phenol formaldehyde (PF) resin into water-swollen cellulose nanofibril (CNF) films. CNF films were prepared using a pressurized filtration method in combination with freeze drying. The freeze-dried films were swollen with water then impregnated with PF resin by soaking in aqueous resin solutions of varying...

TMEM16A Channels Contribute to the Myogenic Response in Cerebral Arteries

PubMed Central

Bulley, Simon; Neeb, Zachary P.; Burris, Sarah K.; Bannister, John P.; Thomas-Gatewood, Candice M.; Jangsangthong, Wanchana; Jaggar, Jonathan H.

2013-01-01

Rationale Pressure-induced arterial depolarization and constriction (the myogenic response), is a smooth muscle cell (myocyte)-specific mechanism that controls regional organ blood flow and systemic blood pressure. Several different non-selective cation channels contribute to pressure-induced depolarization, but signaling mechanisms involved are unclear. Similarly uncertain is the contribution of anion channels to the myogenic response and physiological functions and mechanisms of regulation of recently discovered transmembrane 16A (TMEM16A) chloride (Cl−) channels in arterial myocytes. Objective Investigate the hypothesis that myocyte TMEM16A channels control membrane potential and contractility and contribute to the myogenic response in cerebral arteries. Methods and Results Cell swelling induced by hyposmotic bath solution stimulated Cl− currents in arterial myocytes that were blocked by TMEM16A channel inhibitory antibodies, RNAi-mediated selective TMEM16A channel knockdown, removal of extracellular calcium (Ca2+), replacement of intracellular EGTA with BAPTA, a fast Ca2+ chelator, and Gd3+ and SKF-96365, non-selective cation channel blockers. In contrast, nimodipine, a voltage-dependent Ca2+ channel inhibitor, or thapsigargin, which depletes intracellular Ca2+ stores, did not alter swelling-activated TMEM16A currents. Pressure (−40 mmHg)-induced membrane stretch activated ion channels in arterial myocyte cell-attached patches that were inhibited by TMEM16A antibodies and were of similar amplitude to recombinant TMEM16A channels. TMEM16A knockdown reduced intravascular pressure-induced depolarization and vasoconstriction, but did not alter depolarization (60 mmol/L K+)-induced vasoconstriction. Conclusions Membrane stretch activates arterial myocyte TMEM16A channels, leading to membrane depolarization and vasoconstriction. Data also provide a mechanism by which a local Ca2+ signal generated by non-selective cation channels stimulates TMEM16A channels to induce myogenic constriction. PMID:22872152

How Do Organic Vapors Swell Ultrathin Films of Polymer of Intrinsic Microporosity PIM-1?

PubMed

Ogieglo, Wojciech; Rahimi, Khosorov; Rauer, Sebastian Bernhard; Ghanem, Bader; Ma, Xiaohua; Pinnau, Ingo; Wessling, Matthias

2017-07-27

Dynamic sorption of ethanol and toluene vapor into ultrathin supported films of polymer of intrinsic microporosity PIM-1 down to a thickness of 6 nm are studied with a combination of in situ spectroscopic ellipsometry and in situ X-ray reflectivity. Both ethanol and toluene significantly swell the PIM-1 matrix and, at the same time, induce persistent structural relaxations of the frozen-in glassy PIM-1 morphology. For ethanol below 20 nm, three effects were identified. First, the swelling magnitude at high vapor pressures is reduced by about 30% as compared to that of thicker films. Second, at low penetrant activities (below 0.3p/p 0 ), films below 20 nm are able to absorb slightly more penetrant as compared with thicker films despite a similar swelling magnitude. Third, for the ultrathin films, the onset of the dynamic penetrant-induced glass transition P g has been found to shift to higher values, indicating higher resistance to plasticization. All of these effects are consistent with a view where immobilization of the superglassy PIM-1 at the substrate surface leads to an arrested, even more rigid, and plasticization-resistant, yet still very open, microporous structure. PIM-1 in contact with the larger and more condensable toluene shows very complex, heterogeneous swelling dynamics, and two distinct penetrant-induced relaxation phenomena, probably associated with the film outer surface and the bulk, are detected. Following the direction of the penetrant's diffusion, the surface seems to plasticize earlier than the bulk, and the two relaxations remain well separated down to 6 nm film thickness, where they remarkably merge to form just a single relaxation.

Regulation of the epithelial Na+ channel by membrane tension.

PubMed

Awayda, M S; Subramanyam, M

1998-08-01

The sensitivity of alphabetagamma rat epithelial Na+ channel (rENaC) to osmotically or mechanically induced changes of membrane tension was investigated in the Xenopus oocyte expression system, using both dual electrode voltage clamp and cell-attached patch clamp methodologies. ENaC whole-cell currents were insensitive to mechanical cell swelling caused by direct injection of 90 or 180 nl of 100-mM KCl. Similarly, ENaC whole-cell currents were insensitive to osmotic cell swelling caused by a 33% decrease of bathing solution osmolarity. The lack of an effect of cell swelling on ENaC was independent of the status of the actin cytoskeleton, as ENaC remained insensitive to osmotic and mechanical cell swelling in oocytes pretreated with cytochalasin B for 2-5 h. This apparent insensitivity of ENaC to increased cell volume and changes of membrane tension was also observed at the single channel level in membrane patches subjected to negative or positive pressures of 5 or 10 in. of water. However, and contrary to the lack of an effect of cell swelling, ENaC currents were inhibited by cell shrinking. A 45-min incubation in a 260-mosmol solution (a 25% increase of solution osmolarity) caused a decrease of ENaC currents (at -100 mV) from -3.42 +/- 0.34 to -2.02 +/- 0.23 microA (n = 6). This decrease of current with cell shrinking was completely blocked by pretreatment of oocytes with cytochalasin B, indicating that these changes of current are not likely related to a direct effect of cell shrinking. We conclude that alpha beta gamma rENaC is not directly mechanosensitive when expressed in a system that can produce a channel with identical properties to those found in native epithelia.

Oxygen-deficient metabolism and corneal edema

PubMed Central

Leung, B.K.; Bonanno, J.A.; Radke, C.J.

2014-01-01

Wear of low-oxygen-transmissible soft contact lenses swells the cornea significantly, even during open eye. Although oxygen-deficient corneal edema is well-documented, a self-consistent quantitative prediction based on the underlying metabolic reactions is not available. We present a biochemical description of the human cornea that quantifies hypoxic swelling through the coupled transport of water, salt, and respiratory metabolites. Aerobic and anaerobic consumption of glucose, as well as acidosis and pH buffering, are incorporated in a seven-layer corneal model (anterior chamber, endothelium, stroma, epithelium, postlens tear film, contact lens, and prelens tear film). Corneal swelling is predicted from coupled transport of water, dissolved salts, and especially metabolites, along with membrane-transport resistances at the endothelium and epithelium. At the endothelium, the Na+/K+ - ATPase electrogenic channel actively transports bicarbonate ion from the stroma into the anterior chamber. As captured by the Kedem–Katchalsky membrane-transport formalism, the active bicarbonate-ion flux provides the driving force for corneal fluid pump-out needed to match the leak-in tendency of the stroma. Increased lactate-ion production during hypoxia osmotically lowers the pump-out rate requiring the stroma to swell to higher water content. Concentration profiles are predicted for glucose, water, oxygen, carbon dioxide, and hydronium, lactate, bicarbonate, sodium, and chloride ions, along with electrostatic potential and pressure profiles. Although the active bicarbonate-ion pump at the endothelium drives bicarbonate into the aqueous humor, we find a net flux of bicarbonate ion into the cornea that safeguards against acidosis. For the first time, we predict corneal swelling upon soft-contact-lens wear from fundamental biophysico-chemical principles. We also successfully predict that hypertonic tear alleviates contact-lens-induced edema. PMID:21820076

Oxygen-deficient metabolism and corneal edema.

PubMed

Leung, B K; Bonanno, J A; Radke, C J

2011-11-01

Wear of low-oxygen-transmissible soft contact lenses swells the cornea significantly, even during open eye. Although oxygen-deficient corneal edema is well-documented, a self-consistent quantitative prediction based on the underlying metabolic reactions is not available. We present a biochemical description of the human cornea that quantifies hypoxic swelling through the coupled transport of water, salt, and respiratory metabolites. Aerobic and anaerobic consumption of glucose, as well as acidosis and pH buffering, are incorporated in a seven-layer corneal model (anterior chamber, endothelium, stroma, epithelium, postlens tear film, contact lens, and prelens tear film). Corneal swelling is predicted from coupled transport of water, dissolved salts, and especially metabolites, along with membrane-transport resistances at the endothelium and epithelium. At the endothelium, the Na+/K+ - ATPase electrogenic channel actively transports bicarbonate ion from the stroma into the anterior chamber. As captured by the Kedem-Katchalsky membrane-transport formalism, the active bicarbonate-ion flux provides the driving force for corneal fluid pump-out needed to match the leak-in tendency of the stroma. Increased lactate-ion production during hypoxia osmotically lowers the pump-out rate requiring the stroma to swell to higher water content. Concentration profiles are predicted for glucose, water, oxygen, carbon dioxide, and hydronium, lactate, bicarbonate, sodium, and chloride ions, along with electrostatic potential and pressure profiles. Although the active bicarbonate-ion pump at the endothelium drives bicarbonate into the aqueous humor, we find a net flux of bicarbonate ion into the cornea that safeguards against acidosis. For the first time, we predict corneal swelling upon soft-contact-lens wear from fundamental biophysico-chemical principles. We also successfully predict that hypertonic tear alleviates contact-lens-induced edema. Copyright © 2011 Elsevier Ltd. All rights reserved.

Development and characterization of a gastroretentive dosage form composed of chitosan and hydroxyethyl cellulose for alendronate

PubMed Central

Chen, Ying-Chen; Ho, Hsiu-O; Chiu, Chiao-Chi; Sheu, Ming-Thau

2014-01-01

In this study, alendronate, the most commonly used biphosphonate for treating osteoporosis, was formulated as gastroretentive dosage form (GRDF) tablets to enhance its oral bioavailability. GRDF tablets were characterized with the effects of different molecular weights (MWs) of chitosan (CS) and hydroxyethyl cellulose (HEC) at various ratios on swelling, floating, and physical integrity. The CS component was formed using various acids: acetic, lactic, malic, succinic, and citric, and a high viscosity grade of HEC was selected. The results demonstrated that the swelling ratios of the formulations comprising high MW CS were lower than those of low or medium MW CS when salts were formed with any countering acids except for acetic acid. The decreasing ranking of the swelling rates was: CS-citrate > CS-malate > CS-lactate > CS-succinate > CS-acetate. A negative correlation was found between the pKa of the respective countering acid and the swelling rate. The swelling rate was promoted if an acidic salt of CS with a lower water content was incorporated, while it became slower when tablet hardness was higher or the compression force to form tablets was increased. Although HEC did not contribute to swelling or floating, it played a role in maintaining structural integrity. A prolonged dissolution profile of alendronate GRDF tablets developed in this study was observed. PMID:24403821

Irradiation creep and stress-enhanced swelling of Fe-16Cr-15Ni-Nb austenitic stainless steel in BN-350

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

Vorobjev, A.N.; Porollo, S.I.; Konobeev, Yu.V.

1997-04-01

Irradiation creep and void swelling will be important damage processes for stainless steels when subjected to fusion neutron irradiation at elevated temperatures. The absence of an irradiation device with fusion-relevant neutron spectra requires that data on these processes be collected in surrogate devices such as fast reactors. This paper presents the response of an annealed austenitic steel when exposed to 60 dpa at 480{degrees}C and to 20 dpa at 520{degrees}C. This material was irradiated as thin-walled argon-pressurized tubes in the BN-350 reactor located in Kazakhstan. These tubes were irradiated at hoop stresses ranging from 0 to 200 MPa. After irradiationmore » both destructive and non-destructive examination was conducted.« less

Under pressure: progressively enlarging facial mass following high-pressure paint injection injury.

PubMed

Mushtaq, Jameel; Walker, Abigail; Hunter, Ben

2016-01-19

High-pressure paint injection injuries are relatively rare industrial accidents and almost exclusively occur on the non-dominant hand. A rarely documented complication of these injuries is the formation of a foreign body granuloma. We report a case of a 33-year-old man presenting with extensive facial scarring and progressive right paranasal swelling 7 years after a high-pressure paint injury. After imaging investigations, an excision of the mass and revision of scarring was performed. Access to the mass was gained indirectly through existing scarring over the nose to ensure an aesthetic result. Histological analysis revealed a florid granulomatous foreign body reaction to retained paint. To the best of our knowledge, this is the first reported case of a facial high-pressure paint injury with consequent formation of a foreign body granuloma. 2016 BMJ Publishing Group Ltd.

Dramatic reduction of void swelling by helium in ion-irradiated high purity α-iron

DOE PAGES

Bhattacharya, Arunodaya; Meslin, Estelle; Henry, Jean; ...

2018-04-11

Effect of helium on void swelling was studied in high-purity α-iron, irradiated using energetic self-ions to 157 displacements per atom (dpa) at 773 K, with and without helium co-implantation up to 17 atomic parts-per-million (appm) He/dpa. Helium is known to enhance cavity formation in metals in irradiation environments, leading to early void swelling onset. In this study, microstructure characterization by transmission electron microscopy revealed compelling evidence of dramatic swelling reduction by helium co-implantation, achieved primarily by cavity size reduction. In conclusion, a comprehensive understanding of helium induced cavity microstructure development is discussed using sink strength ratios of dislocations and cavities.

Using CO2 Prophet to estimate recovery factors for carbon dioxide enhanced oil recovery

USGS Publications Warehouse

Attanasi, Emil D.

2017-07-17

IntroductionThe Oil and Gas Journal’s enhanced oil recovery (EOR) survey for 2014 (Koottungal, 2014) showed that gas injection is the most frequently applied method of EOR in the United States and that carbon dioxide (CO2 ) is the most commonly used injection fluid for miscible operations. The CO2-EOR process typically follows primary and secondary (waterflood) phases of oil reservoir development. The common objective of implementing a CO2-EOR program is to produce oil that remains after the economic limit of waterflood recovery is reached. Under conditions of miscibility or multicontact miscibility, the injected CO2 partitions between the gas and liquid CO2 phases, swells the oil, and reduces the viscosity of the residual oil so that the lighter fractions of the oil vaporize and mix with the CO2 gas phase (Teletzke and others, 2005). Miscibility occurs when the reservoir pressure is at least at the minimum miscibility pressure (MMP). The MMP depends, in turn, on oil composition, impurities of the CO2 injection stream, and reservoir temperature. At pressures below the MMP, component partitioning, oil swelling, and viscosity reduction occur, but the efficiency is increasingly reduced as the pressure falls farther below the MMP. CO2-EOR processes are applied at the reservoir level, where a reservoir is defined as an underground formation containing an individual and separate pool of producible hydrocarbons that is confined by impermeable rock or water barriers and is characterized by a single natural pressure system. A field may consist of a single reservoir or multiple reservoirs that are not in communication but which may be associated with or related to a single structural or stratigraphic feature (U.S. Energy Information Administration [EIA], 2000). The purpose of modeling the CO2-EOR process is discussed along with the potential CO2-EOR predictive models. The data demands of models and the scope of the assessments require tradeoffs between reservoir-specific data that can be assembled and simplifying assumptions that allow assignment of default values for some reservoir parameters. These issues are discussed in the context of the CO2 Prophet EOR model, and their resolution is demonstrated with the computation of recovery-factor estimates for CO2-EOR of 143 reservoirs in the Powder River Basin Province in southeastern Montana and northeastern Wyoming.

Microstructural characterization and density change of 304 stainless steel reflector blocks after long-term irradiation in EBR-II

NASA Astrophysics Data System (ADS)

Huang, Y.; Wiezorek, J. M. K.; Garner, F. A.; Freyer, P. D.; Okita, T.; Sagisaka, M.; Isobe, Y.; Allen, T. R.

2015-10-01

While thin reactor structural components such as cladding and ducts do not experience significant gradients in dpa rate, gamma heating rate, temperature or stress, thick components can develop strong local variations in void swelling and irradiation creep in response to gradients in these variables. In this study we conducted microstructural investigations by transmission electron microscopy of two 52 mm thick 304-type stainless steel hex-blocks irradiated for 12 years in the EBR-II reactor with accumulated doses ranging from ∼0.4 to 33 dpa. Spatial variations in the populations of voids, precipitates, Frank loops and dislocation lines have been determined for 304 stainless steel sections exposed to different temperatures, different dpa levels and at different dpa rates, demonstrating the existence of spatial gradients in the resulting void swelling. The microstructural measurements compare very well with complementary density change measurements regarding void swelling gradients in the 304 stainless steel hex-block components. The TEM studies revealed that the original cold-worked-state microstructure of the unirradiated blocks was completely erased by irradiation, replaced by high densities of interstitial Frank loops, voids and carbide precipitates at both the lowest and highest doses. At large dose levels the amount of volumetric void swelling correlated directly with the gamma heating gradient-related temperature increase (e.g. for 28 dpa, ∼2% swelling at 418 °C and ∼2.9% swelling at 448 °C). Under approximately iso-thermal local conditions, volumetric void swelling was found to increase with dose level (e.g. ∼0.2% swelling at 0.4 dpa, ∼0.5% swelling at 4 dpa and ∼2% swelling at 28 dpa). Carbide precipitate formation levels were found to be relatively independent of both dpa level and temperature and induced a measurable densification. Void swelling was dominant at the higher dose levels and caused measurable decreases in density. Void swelling at the lowest doses was larger than might be expected based on the dpa level, an observation in agreement with earlier studies showing that the onset of void swelling is accelerated by decreasing dpa rates.

Development of a novel drug release system, time-controlled explosion system (TES). I. Concept and design.

PubMed

Ueda, S; Hata, T; Asakura, S; Yamaguchi, H; Kotani, M; Ueda, Y

1994-01-01

A novel controlled drug release system. Time-Controlled Explosion System (TES) has been developed. TES has a four-layered spherical structure, which consists of core, drug, swelling agent and water insoluble polymer membrane. TES is characterized by a rapid drug release with a precisely programmed lag time; i.e. expansion of the swelling agent by water penetrating through the outer membrane, destruction of the membrane by stress due to swelling force and subsequent rapid drug release. For establishing the concept and development strategy, TES was designed using metoprolol and polystyrene balls (size: 3.2 mm in diameter) as a model drug and core particles. Among the polymers screened, low-substituted hydroxypropylcellulose (L-HPC) and ethylcellulose (EC) were selected for a swelling agent and an outer water insoluble membrane, respectively. The release profiles of metoprolol from the system were not affected by the pH of the dissolution media. Lag time was controlled by the thickness of the outer EC membrane; thus, a combination of TES particles possessing different lag times could offer any desired release profile of the model compound, metoprolol.

Intracanalicular Optic Nerve Swelling and Signal Change in Fulminant Untreated Idiopathic Intracranial Hypertension.

PubMed

Moodley, Anand A; Dlwati, Mahlubonke S; Durand, Miranda

2017-04-01

The role of the optic canal in the pathogenesis of papilloedema has been under scrutiny recently. Whether a larger canal precedes more severe papilloedema or is the result of bone remodelling from chronically raised pressure across a pressure gradient is not clear. The authors present the magnetic resonance imaging findings of a 29-year-old female with fulminant and untreated idiopathic intracranial hypertension. Imaging showed focal expansion and intrinsic signal changes of the intracanalicular optic nerve. The authors discuss the possibility of either fluid accumulation within the optic nerves from a water hammer effect across blocked optic canals resulting from the steep pressure gradient or opticomalacia (optic nerve softening) from chronic ischaemia.

Cracking up (and down): Linking multi-domain hydraulic properties with multi-scale hydrological processes in shrink-swell soils

NASA Astrophysics Data System (ADS)

Stewart, R. D.; Rupp, D. E.; Abou Najm, M. R.; Selker, J. S.

2017-12-01

Shrink-swell soils, often classified as Vertisols or vertic intergrades, are found on every continent except Antarctica and within many agricultural and urban regions. These soils are characterized by cyclical shrinking and swelling, in which bulk density and porosity distributions vary as functions of time and soil moisture. Crack networks that form in these soils act as dominant environmental controls on the movement of water, contaminants, and gases, making it important to develop fundamental understanding and tractable models of their hydrologic characteristics and behaviors. In this study, which took place primarily in the Secano Interior region of South-Central Chile, we quantified soil-water interactions across scales using a diverse and innovative dataset. These measurements were then utilized to develop a set of parsimonious multi-domain models for describing hydraulic properties and hydrological processes in shrink-swell soils. In a series of examples, we show how this model can predict porosity distributions, crack widths, saturated hydraulic conductivities, and surface runoff (i.e., overland flow) thresholds, by capturing the dominant mechanisms by which water moves through and interacts with clayey soils. Altogether, these models successfully link small-scale shrinkage/swelling behaviors with large-scale thresholds, and can be applied to describe important processes such as infiltration, overland flow development, and the preferential flow and transport of fluids and gases.

Hydrogel based sensor arrays (2 × 2) with perforated piezoresistive diaphragms for metabolic monitoring (in vitro)

PubMed Central

Orthner, M.P.; Lin, G.; Avula, M.; Buetefisch, S.; Magda, J.; Rieth, L.W.; Solzbacher, F.

2010-01-01

This report details the first experimental results from novel hydrogel sensor array (2 × 2) which incorporates analyte diffusion pores into a piezoresistive diaphragm for the detection of hydrogel swelling pressures and hence chemical concentrations. The sensor assembly was comprised of three components, the active four sensors, HPMA/DMA/TEGDMA (hydroxypropyl methacrylate (HPMA), N,N-dimethylaminoethyl methacrylate (DMA) and crosslinker tetra-ethyleneglycol dimethacrylate (TEGDMA)) hydrogel, and backing plate. Each of the individual sensors of the array can be used with various hydrogels used to measure the presence of a number of stimuli including pH, ionic strength, and glucose concentrations. Ideally, in the future, these sensors will be used for continuous metabolic monitoring applications and implanted subcutaneously. In this paper and to properly characterize the sensor assembly, hydrogels sensitive to changes ionic strength were synthesized using hydroxypropyl methacrylate (HPMA), N,N-dimethylaminoethyl methacrylate (DMA) and crosslinker tetra-ethyleneglycol dimethacrylate (TEGDMA) and inserted into the sensor assembly. This hydrogel quickly and reversibly swells when placed environments of physiological buffer solutions (PBS) with ionic strengths ranging from 0.025 to 0.15 M, making it ideal for proof-of-concept testing and initial characterization. The assembly was wire bonded to a printed circuit board and coated with 3 ± 0.5 μm of Parylene-C using chemical vapor deposition (CVD) to protect the sensor and electrical connections during ionic strength wet testing. Two versions of sensors were fabricated for comparison, the first incorporated diffusion pores into the diaphragm, and the second used a solid diaphragm with perforated backing plate. This new design (perforated diaphragm) was shown to have slightly higher sensitivity than solid diaphragm sensors with separate diffuse backing plates when coupled with the hydrogel. The sensitivities for the 1 mm × 1 mm, 1.25 mm × 1.25 mm, 1.5 mm × 1.5 mm perforated diaphragm sensors were 53.3 ± 6.5, 171.7 ± 8.8, and 271.47 ± 27.53 mV/V-M, respectively. These results show that perforations in the diaphragm can be used not only to allow the diffusion of analyte into the cavity but to increase mechanical stress in the piezoresistive diaphragm, thereby increasing sensor output signal. The time constants for swelling (τswelling) and contracting (τcontracting) were calculated by fitting the sensor output half cycles to an exponential growth function. We found that the sensors' response was initially retarded during the preliminary hydrogel conditioning period then improved after 3–5 cycles with values of approximately 9 and 7 min for τswelling and τcontracting. For all sensors tested τswelling > τcontracting. This may be due to the increased loading on the hydrogel from the diaphragm during the swelling process. During contraction the diaphragm aids the hydrogel by reversibly applying mechanical pressure and therefore reducing τcontracting. Long term stability testing showed the sensors remained functional for upwards of 2 weeks in the test phosphate buffer solution (PBS). PMID:23750073

Hydrogel based sensor arrays (2 × 2) with perforated piezoresistive diaphragms for metabolic monitoring (in vitro).

PubMed

Orthner, M P; Lin, G; Avula, M; Buetefisch, S; Magda, J; Rieth, L W; Solzbacher, F

2010-03-19

This report details the first experimental results from novel hydrogel sensor array (2 × 2) which incorporates analyte diffusion pores into a piezoresistive diaphragm for the detection of hydrogel swelling pressures and hence chemical concentrations. The sensor assembly was comprised of three components, the active four sensors, HPMA/DMA/TEGDMA (hydroxypropyl methacrylate (HPMA), N,N-dimethylaminoethyl methacrylate (DMA) and crosslinker tetra-ethyleneglycol dimethacrylate (TEGDMA)) hydrogel, and backing plate. Each of the individual sensors of the array can be used with various hydrogels used to measure the presence of a number of stimuli including pH, ionic strength, and glucose concentrations. Ideally, in the future, these sensors will be used for continuous metabolic monitoring applications and implanted subcutaneously. In this paper and to properly characterize the sensor assembly, hydrogels sensitive to changes ionic strength were synthesized using hydroxypropyl methacrylate (HPMA), N,N-dimethylaminoethyl methacrylate (DMA) and crosslinker tetra-ethyleneglycol dimethacrylate (TEGDMA) and inserted into the sensor assembly. This hydrogel quickly and reversibly swells when placed environments of physiological buffer solutions (PBS) with ionic strengths ranging from 0.025 to 0.15 M, making it ideal for proof-of-concept testing and initial characterization. The assembly was wire bonded to a printed circuit board and coated with 3 ± 0.5 μm of Parylene-C using chemical vapor deposition (CVD) to protect the sensor and electrical connections during ionic strength wet testing. Two versions of sensors were fabricated for comparison, the first incorporated diffusion pores into the diaphragm, and the second used a solid diaphragm with perforated backing plate. This new design (perforated diaphragm) was shown to have slightly higher sensitivity than solid diaphragm sensors with separate diffuse backing plates when coupled with the hydrogel. The sensitivities for the 1 mm × 1 mm, 1.25 mm × 1.25 mm, 1.5 mm × 1.5 mm perforated diaphragm sensors were 53.3 ± 6.5, 171.7 ± 8.8, and 271.47 ± 27.53 mV/V-M, respectively. These results show that perforations in the diaphragm can be used not only to allow the diffusion of analyte into the cavity but to increase mechanical stress in the piezoresistive diaphragm, thereby increasing sensor output signal. The time constants for swelling ( τ swelling ) and contracting ( τ contracting ) were calculated by fitting the sensor output half cycles to an exponential growth function. We found that the sensors' response was initially retarded during the preliminary hydrogel conditioning period then improved after 3-5 cycles with values of approximately 9 and 7 min for τ swelling and τ contracting . For all sensors tested τ swelling > τ contracting . This may be due to the increased loading on the hydrogel from the diaphragm during the swelling process. During contraction the diaphragm aids the hydrogel by reversibly applying mechanical pressure and therefore reducing τ contracting . Long term stability testing showed the sensors remained functional for upwards of 2 weeks in the test phosphate buffer solution (PBS).

What can asymmetry tell us? Investigation of asymmetric versus symmetric pinch and swell structures in nature and simulation

NASA Astrophysics Data System (ADS)

Gardner, Robyn; Piazolo, Sandra; Daczko, Nathan

2015-04-01

Pinch and swell structures occur from microscopic to landscape scales where a more competent layer in a weaker matrix is deformed by pure shear, often in rifting environments. The Anita Shear Zone (ASZ) in Fiordland, New Zealand has an example of landscape scale (1 km width) asymmetric pinch and swell structures developed in ultramafic rocks. Field work suggests that the asymmetry is a result of variations in the surrounding 'matrix' flow properties as the ultramafic band is surrounded to the east by an orthogneiss (Milford Orthogneiss) and to the west by a paragneiss (Thurso Paragneiss). In addition, there is a narrow and a much wider shear zone between the ultramafics and the orthogneiss and paragneiss, respectively. Detailed EBSD analysis of samples from a traverse across the pinch and swell structure indicate the ultramafics in the shear zone on the orthogneiss side have larger grain size than the ultramafics in the shear zone on the paragneiss side. Ultramafic samples from the highly strained paragneiss and orthogneiss shear zones show dislocation creep behaviour, and, on the paragneiss side, also significant deformation by grain boundary sliding. To test if asymmetry of pinch and swell structures can be used to derive the rheological properties of not only the pinch and swell lithologies, but also of the matrix, numerical simulations were performed. Numerical modelling of pure shear (extension) was undertaken with (I) initially three layers and then (II) five layers by adding soft high strain zones on both sides of the rheological hard layer. The matrix was given first symmetric, then asymmetric viscosity. Matrix viscosity was found to impact the formation of pinch and swell structures with the weaker layer causing increased tortuosity of the competent layer edge due to increased local differential stress. Results highlight that local, rheologically soft layers and the relative viscosity of matrix both impact significantly the shape and symmetry of developing pinch and swell structures.

Fuel swelling and interaction layer formation in the SELENIUM Si and ZrN coated U(Mo) dispersion fuel plates irradiated at high power in BR2

NASA Astrophysics Data System (ADS)

Leenaers, A.; Van den Berghe, S.; Koonen, E.; Kuzminov, V.; Detavernier, C.

2015-03-01

In the framework of the SELENIUM project two full size flat fuel plates were produced with respectively Si and ZrN coated U(Mo) particles and irradiated in the BR2 reactor at SCK•CEN. Non-destructive analysis of the plates showed that the fuel swelling profiles of both SELENIUM plates were very similar to each other and none of the plates showed signs of pillowing or excessive swelling at the end of irradiation at the highest power position (local maximum 70% 235U). The microstructural analysis showed that the Si coated fuel has less interaction phase formation at low burn-up but at the highest burn-ups, defects start to develop on the IL-matrix interface. The ZrN coated fuel, shows a virtual absence of reaction between the U(Mo) and the Al, up to high fission densities after which the interaction layer formation starts and defects develop in the matrix near the U(Mo) particles. It was found and is confirmed by the SELENIUM (Surface Engineering of Low ENrIched Uranium-Molybdenum) experiment that there are two phenomena at play that need to be controlled: the formation of an interaction layer and swelling of the fuel. As the interaction layer formation occurs at the U(Mo)-matrix interface, applying a diffusion barrier (coating) at that interface should prevent the interaction between U(Mo) and the matrix. The U(Mo) swelling, observed to proceed at an accelerating rate with respect to fission density accumulation, is governed by linear solid state swelling and fission gas bubble swelling due to recrystallization of the fuel. The examination of the SELENIUM fuel plates clearly show that for the U(Mo) dispersion fuel to be qualified, the swelling rate at high burn-up needs to be reduced.

NF-κB in The Mechanism of Brain Edema in Acute Liver Failure: Studies in Transgenic Mice

PubMed Central

Jayakumar, A.R.; Bethea, J.R.; Tong, X.Y.; Gomez, J.; Norenberg, M.D.

2014-01-01

Astrocyte swelling and brain edema are major complications of the acute form of hepatic encephalopathy (acute liver failure, ALF). While elevated brain ammonia level is a well-known etiological factor in ALF, the mechanism by which ammonia brings about astrocyte swelling is not well understood. We recently found that astrocyte cultures exposed to ammonia activated nuclear factor-kappaB (NF-κB), and that pharmacological inhibition of such activation led to a reduction in astrocyte swelling. Although these findings suggest the involvement of NF-κB in astrocyte swelling in vitro, it is not known whether NF-κB contributes to the development of brain edema in ALF in vivo. Furthermore, pharmacological agents used to inhibit NF-κB may have non-specific effects. Accordingly, we used transgenic (Tg) mice that have a functional inactivation of astrocytic NF-κB and examined whether these mice are resistant to ALF-associated brain edema. ALF was induced in mice by treatment with the hepatotoxin thioacetamide (TAA). Wild type (WT) mice treated with TAA showed a significant increase in brain water content (1.65%) along with prominent astrocyte swelling and spongiosis of the neuropil, consistent with the presence of cytotoxic edema. These changes were not observed in Tg mice treated with TAA. Additionally, WT mice with ALF showed an increase in inducible nitric oxide synthase (iNOS) immunoreactivity in astrocytes from WT mice treated with TAA (iNOS is known to be activated by NF-κB and to contribute to cell swelling). By contrast, Tg mice treated with TAA did not exhibit brain edema, histological changes nor an increase in iNOS immunoreactivity. We also examined astrocytes cultures derived from Tg mice to determine whether these cells exhibit a lesser degree of swelling and cytopathological changes following exposure to ammonia. Astrocyte cultures derived from Tg mice showed no cell swelling nor morphological abnormalities when exposed to ammonia for 24 h. By contrast, ammonia significantly increased cell swelling (31.7%) in cultured astrocytes from WT mice and displayed cytological abnormalities. Moreover, we observed a lesser increment in inducible nitric oxide synthase and NADPH oxidase activity (both are also known to be activated by NF-κB and to contribute to astrocyte swelling) in astrocyte cultures from Tg mice treated with ammonia, as compared to ammonia-treated WT mice astrocytes. These findings strongly suggest that activation of NF-κB is a critical factor in the development of astrocyte swelling/brain edema in ALF. PMID:21087666

A Means of Predicting Swelling Pressures of Soils Found in the Rocky Mountain Area.

DTIC Science & Technology

1980-05-19

also known as nattahalloysite. or halLoysite (2H 2 0) noupiestic: Al4Si4 Oio(OH)sr 5. Endellite, also known as halloysite , hydrated hallo)-site. or... halloysite (4H20) nonpstic: AS0001O-42 Aloft: Halloysits (4HIO) lowos water between site and laboratory at moderate tempematures, to form metaballoysite

Poro-elasto-capillary wicking of cellulose sponges

PubMed Central

Kim, Do-Nyun

2018-01-01

We mundanely observe cellulose (kitchen) sponges swell while absorbing water. Fluid flows in deformable porous media, such as soils and hydrogels, are classically described on the basis of the theories of Darcy and poroelasticity, where the expansion of media arises due to increased pore pressure. However, the situation is qualitatively different in cellulosic porous materials like sponges because the pore expansion is driven by wetting of the surrounding cellulose walls rather than by increase of the internal pore pressure. We address a seemingly so simple but hitherto unanswered question of how fast water wicks into the swelling sponge. Our experiments uncover a power law of the wicking height versus time distinct from that for nonswelling materials. The observation using environmental scanning electron microscopy reveals the coalescence of microscale wall pores with wetting, which allows us to build a mathematical model for pore size evolution and the consequent wicking dynamics. Our study sheds light on the physics of water absorption in hygroscopically responsive multiscale porous materials, which have far more implications than everyday activities (for example, cleaning, writing, and painting) carried out with cellulosic materials (paper and sponge), including absorbent hygiene products, biomedical cell cultures, building safety, and cooking. PMID:29682606

Gluteal Compartment Syndrome following an Iliac Bone Marrow Aspiration

PubMed Central

Vega-Najera, Carlos; Leal-Contreras, Carlos; Leal-Berumen, Irene

2013-01-01

The compartment syndrome is a condition characterized by a raised hydraulic pressure within a closed and non expandable anatomical space. It leads to a vascular insufficiency that becomes critical once the vascular flow cannot return the fluids back to the venous system. This causes a potential irreversible damage of the contents of the compartment, especially within the muscle tissues. Gluteal compartment syndrome (GCS) secondary to hematomas is seldom reported. Here we present a case of a 51-year-old patient with history of a non-Hodgkin lymphoma who underwent a bone marrow aspiration from the posterior iliac crest that had excessive bleeding at the puncture zone. The patient complained of increasing pain, tenderness, and buttock swelling. Intraoperative pressure validation of the gluteal compartment was performed, and a GCS was diagnosed. The patient was treated with a gluteal region fasciotomy. The patient recovered from pain and swelling and was discharged shortly after from the hospital. We believe clotting and hematologic disorders are a primary risk factor in patients who require bone marrow aspirations or biopsies. It is important to improve awareness of GCS in order to achieve early diagnosis, avoid complications, and have a better prognosis. PMID:24392235

The analysis of creep characteristics of the surrounding rock of the carbonaceous rock tunnel based on Singh-Mitchell model

NASA Astrophysics Data System (ADS)

Luo, Junhui; Mi, Decai; Ye, Qiongyao; Deng, Shengqiang; Zeng, Fuquan; Zeng, Yongjun

2018-01-01

Carbonaceous rock has the characteristics of easy disintegration, softening, swelling and environmental sensitivity, which belongs to soft surrounding rock, and the deformation during excavation and long-term stability of the surrounding rock of carbonaceous rock tunnel are common problems in the construction of carbonaceous rock tunnel. According to the above, the Monitor and measure the displacement, temperature and osmotic pressure of the surrounding carbonaceous rock of the tunnel of Guangxi Hebai highway. Then it based on the obtaining data to study the creep mechanism of surrounding rock using Singh-Mitchell model and predict the deformation of surrounding rock before the tunnel is operation. The results show that the Singh-Mitchell creep model can effectively analyse and predict the deformation development law of surrounding rock of tunnel without considering temperature and osmotic pressure, it can provide reference for the construction of carbonaceous rock tunnel and the measures to prevent and reinforce it..

Unrecognized anterior compartment syndrome following ankle fracture surgery: a case report.

PubMed

Seyahi, Aksel; Uludag, Serkan; Akman, Senol; Demirhan, Mehmet

2009-01-01

A 35-year-old male sustained a lateral malleolar fracture while playing football. The fracture was treated by open reduction and internal fixation with a tourniquet. The next day, the patient returned with pain and swelling of the ankle and was admitted again to the hospital with a suspected diagnosis of cellulitis. Ten hours later, the patient developed the symptoms of anterior compartment syndrome. Emergency open fasciotomy of the anterior compartment was performed. The retrospective analysis of the patient's history was suggestive of a predisposition to an exercise-induced compartment syndrome. We think that exertional increase of the compartmental pressure before the injury and the tourniquet used during surgery contributed together to the development of compartment syndrome. Physicians should be vigilant in identifying the features of compartment syndrome when managing patients injured during a sporting activity.

Foot Comfort for the Fashionable

NASA Technical Reports Server (NTRS)

2002-01-01

Modellista Footwear's new shoe line uses Tempur(TM) material, which conforms to each wearer's unique foot shape to absorb shock and cushion the foot. The foam's properties allow the shoe to change with the wearer's foot as it shrinks and swells throughout the day. Scientists at NASA's Ames Research Center originally developed temper foam in the early 1970s to relieve the intense pressure of G-forces experienced by astronauts during rocket launches. Tempur-Pedic, Inc., further developed the foam and granted Modellista a license to use it in footwear. The Modellista collection is the first shoe design and construction to be certified by the Space Awareness Alliance. The shoes, with designs ranging from traditional clog shapes to sling backs and open-toe sandals, are currently available nationwide at select specialty shoe stores and through catalogs. Tempur(TM) is a registered trademark of Tempur-Pedic, Inc.

Paradoxes of thermodynamics of swelling equilibria of polymers in liquids and vapors.

PubMed

Davankov, Vadim A; Pastukhov, Alexander V

2011-12-29

An automatic registration of the changing size of a single spherical microbead of a cross-linked polymer was applied for studying the swelling process of the bead by the sorption of vapors and/or liquids. Many representatives of all three basic types of polymeric networks, gel-type, hypercrosslinked, and macroporous, were examined. Only the first two display large volume changes and prove suitable for following the kinetics and extent of swelling by the above dilatometric technique. The results unambiguously prove that swelling of all polymeric networks in liquids is always higher than in corresponding saturated vapors (Schroeder's paradox). The general nature of this phenomenon implies that the absolute activity of any sorbate in its liquid form is always larger than in the form of its saturated vapor. Surprisingly, gels with any solvent contents, which fall into the broad range between the vapor-equilibrated and liquid-equilibrated extreme contents, retain their volumes constant in the saturated vapor atmosphere. This paradox of a wide range of gels swollen to a different extent and, nevertheless, standing in equilibrium with saturated vapor is explained by the specificity of the network polymers, namely, that the energy of the solvent-polymer interactions is easily compensated by the energy of remaining between-chain interactions at any solvent content in the above range. Therefore, the strain-free swollen gels do not generate enhanced vapor pressure, but neither display the ability to take up more sorbate from its vapor. © 2011 American Chemical Society

[A woman with a postoperative lumbar swelling].

PubMed

Hulshof, Hanna M; Elsenburg, Patric H J M; Frequin, Stephan T F M

2013-01-01

A 65-year-old woman had developed a large lumbar swelling in a period of four weeks following lumbar laminectomy. An MRI-scan revealed a large fluid collection, which had formed from the spinal canal. The diagnosis 'liquorcele', a rare complication of spine surgery, was established.

Low Activation Joining of SiC/SiC Composites for Fusion Applications: Modeling Thermal and Irradiation-induced Swelling Effects on Integrity of Ti3SiC2/SiC Joint

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

Nguyen, Ba Nghiep; Henager, Charles H.; Kurtz, Richard J.

This work developed a continuum damage mechanics model that incorporates thermal expansion combined with irradiation-induced swelling effects to study the origin of cracking observed in recent irradiation experiments. Micromechanical modeling using an Eshelby-Mori-Tanaka approach was used to compute the thermoelastic properties of the Ti3SiC2/SiC joint needed for the model. In addition, a microstructural dual-phase Ti3SiC2/SiC model was developed to determine irradiation-induced swelling of the composite joint at a given temperature resulting from differential swelling of SiC and the Ti3SiC2 MAX phase. Three cases for the miniature torsion hourglass (THG) specimens containing a Ti3SiC2/SiC joint were analyzed corresponding to three irradiationmore » temperatures: 800oC, 500oC, and 400oC.« less

A β-cyclodextrin, polyethyleneimine and silk fibroin hydrogel containing Centella asiatica extract and hydrocortisone acetate: releasing properties and in vivo efficacy for healing of pressure sores.

PubMed

Lee, M S; Seo, S R; Kim, J-C

2012-10-01

  Pressure sores are lesions caused by impaired blood flow. Conventional dressings can absorb exudates, but do not promote wound healing. A hydrogel composed of β-cyclodextrin (β-CD), polyethyleneimine (PEI) and silk fibroin (SF) was assessed for use in healing of pressure sores. The hydrogel was prepared by crosslinking β-CD-grafted PEI and SF using epichlorohydrin. The gel was then immersed in an aqueous solution of Centella asiatica extract (CAE) 0.7 mg/mL and/or hydrocortisone acetate (HCA) 0.5 mg/mL. The in vivo pressure sore-healing efficacy of the dry gel (with or without the drugs) was investigated in terms of the hyperplasia of epidermis and the number of neutrophils in the skin tissue. The specific loading of CAE was 0.0091 g/g of dry gel. The percentage of CAE released at 24 h at pH 3.0, 5.0 and 7.4 was approximately 63.9%, 55.0% and 44.4%, respectively. This pH-dependent release is possibly due to the degree of gel swelling, which decreased with increasing pH. The specific loading of HCA was 0.0050 g/g dry gel, and the percentage release of HCA at 24 h was around 20% at all three pH points. It is likely that HCA release is independent of pH. HCA is a hydrophobic compound, and therefore the release of HCA is affected by the partitioning of HCA between the β-CD cavity and the bulk water phase, but not by the degree of swelling of the hydrogel. The pressure sores treated with the hydrogel healed in 6 days, compared with 10 days for controls. In this study, a β-CD/PEI/SF hydrogel containing CAE and HCA reduced the healing time for pressure sores. © The Author(s). CED © 2012 British Association of Dermatologists.

In situ investigation of supercritical CO2 assisted impregnation of drugs into a polymer by high pressure FTIR micro-spectroscopy.

PubMed

Champeau, M; Thomassin, J-M; Jérôme, C; Tassaing, T

2015-02-07

An original experimental set-up combining a FTIR micro-spectrometer with a high pressure cell has been built in order to analyze in situ the impregnation of a solute into microscopic polymer samples, such as fibers or films, subjected to supercritical CO2. Thanks to this experimental set-up, key factors governing the impregnation process can be simultaneously followed such as the swelling of the polymeric matrix, the CO2 sorption, the kinetics of impregnation and the drug loading into the matrix. Moreover, the solute/polymer interactions and the speciation of the solute can be analyzed. We have monitored in situ the impregnation of aspirin and ketoprofen into PEO (Polyethylene Oxide) platelets at T = 40 °C and P = 5; 10 and 15 MPa. The kinetics of impregnation of aspirin was quicker than the one of ketoprofen and the final drug loading was also higher in the case of aspirin. Whereas the CO2 sorption and the PEO swelling remain constant when PEO is just subjected to CO2 under isobaric conditions, we noticed that both parameters can increase while the drug impregnates PEO. Coupling these results with DSC measurements, we underlined the plasticizing effect of the drug that also leads to a decrease in the crystallinity of PEO in situ thus favoring the sorption of CO2 molecules into the matrix and the swelling of the matrix. The plasticizing effect increases with the drug loading. Finally, the speciation of drugs was investigated considering the shift of the carboxyl bands of the drugs. Both drugs were found to be mainly homogeneously dispersed into PEO.

Effects of matrix shrinkage and swelling on the economics of enhanced-coalbed-methane production and CO{sub 2} sequestration in coal

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

Gorucu, F.B.; Jikich, S.A.; Bromhal, G.S.

2007-08-15

In this work, the Palmer-Mansoori model for coal shrinkage and permeability increases during primary methane production was rewritten to also account for coal swelling caused by CO{sub 2} sorption. The generalized model was added to a compositional, dual porosity coalbed-methane reservoir simulator for primary (CBM) and ECBM production. A standard five-spot of vertical wells and representative coal properties for Appalachian coals was used. Simulations and sensitivity analyses were performed with the modified simulator for nine different parameters, including coal seam and operational parameters and economic criteria. The coal properties and operating parameters that were varied included Young's modulus, Poisson's ratio,more » cleat porosity, and injection pressure. The economic variables included CH{sub 4}, price, Col Cost, CO{sub 2} credit, water disposal cost, and interest rate. Net-present value (NPV) analyses of the simulation results included profits resulting from CH{sub 4}, production and potential incentives for sequestered CO{sub 2}, This work shows that for some coal seams, the combination of compressibility, cleat porosity, and shrinkage/swelling of the coal may have a significant impact on project economics.« less

Chitin's Functionality as a Novel Disintegrant: Benchmarking Against Commonly Used Disintegrants in Different Physicochemical Environments.

PubMed

Chaheen, Mohammad; Soulairol, Ian; Bataille, Bernard; Yassine, Ahmad; Belamie, Emmanuel; Sharkawi, Tahmer

2017-07-01

Disintegrants are used as excipients to ensure rapid disintegration of pharmaceutical tablets and further ensure proper dissolution of the active pharmaceutical ingredient. This study investigates disintegration mechanisms of chitin and common disintegrants. Swelling assessment (swelling force and swelling ratio) in different media, and compaction behavior (pure or mixed with other excipients) tabletability, deformation (Heckel modeling), and compact disintegration times were investigated on the tested disintegrants (alginic acid calcium salt, crospovidone, sodium starch glycolate, croscarmellose sodium, and chitin). Results show that the physicochemical properties of the disintegration medium such as pH and ionic strength, as well as other formulation ingredients, affect the disintegrant functionalities. Heckel analysis using the mean yield pressure "Py" shows that alginic acid calcium salt is the most brittle among the studied disintegrants, while crospovidone has the most plastic deformation mechanism, followed by chitin. Chitin showed good tabletability and disintegration properties that were not influenced by the physicochemical formulation environment. Chitin is largely available and easily modifiable and thus a promising material that could be used as a multifunctional excipient in tablet formulation. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Sulfur removal and comminution of carbonaceous material

DOEpatents

Narain, N.K.; Ruether, J.A.; Smith, D.N.

1987-10-07

Finely divided, clean coal or other carbonaceous material is provided by forming a slurry of coarse coal in aqueous alkali solution and heating the slurry under pressure to above the critical conditions of steam. The supercritical fluid penetrates and is trapped in the porosity of the coal as it swells in a thermoplastic condition at elevated temperature. By a sudden, explosive release of pressure the coal is fractured into finely divided particles with release of sulfur-containing gases and minerals. The finely divided coal is recovered from the minerals for use as a clean coal product. 2 figs.

Smart responsive microcapsules capable of recognizing heavy metal ions.

PubMed

Pi, Shuo-Wei; Ju, Xiao-Jie; Wu, Han-Guang; Xie, Rui; Chu, Liang-Yin

2010-09-15

Smart responsive microcapsules capable of recognizing heavy metal ions are successfully prepared with oil-in-water-in-oil double emulsions as templates for polymerization in this study. The microcapsules are featured with thin poly(N-isopropylacrylamide-co-benzo-18-crown-6-acrylamide) (P(NIPAM-co-BCAm)) membranes, and they can selectively recognize special heavy metal ions such as barium(II) or lead(II) ions very well due to the "host-guest" complexation between the BCAm receptors and barium(II) or lead(II) ions. The stable BCAm/Ba(2+) or BCAm/Pb(2+) complexes in the P(NIPAM-co-BCAm) membrane cause a positive shift of the volume phase transition temperature of the crosslinked P(NIPAM-co-BCAm) hydrogel to a higher temperature, and the repulsion among the charged BCAm/Ba(2+) or BCAm/Pb(2+) complexes and the osmotic pressure within the P(NIPAM-co-BCAm) membranes result in the swelling of microcapsules. Induced by recognizing barium(II) or lead(II) ions, the prepared microcapsules with P(NIPAM-co-BCAm) membranes exhibit isothermal and significant swelling not only in outer and inner diameters but also in the membrane thickness. The proposed microcapsules in this study are highly attractive for developing smart sensors and/or carriers for detection and/or elimination of heavy metal ions. Copyright 2010 Elsevier Inc. All rights reserved.

Elevated compartment pressures from copperhead envenomation successfully treated with antivenin.

PubMed

Mazer-Amirshahi, Maryann; Boutsikaris, Amy; Clancy, Cathleen

2014-01-01

Copperhead envenomation causes local soft tissue effects; however, associated compartment syndrome is rare. We report a case of a 17-month-old with significantly elevated compartment pressures successfully treated with antivenin and supportive care. A 17-month-old girl sustained a copperhead bite to the foot and presented with circumferential edema, erythema, and ecchymosis of the foot and distal ankle. The patient had palpable pulses and was neurologically intact. Four vials of Crotalidae polyvalent immune Fab was initiated and additional doses were administered in an attempt to achieve local control. Within 10 h of presentation, the patient's edema extended to the groin, although sensation was maintained and pulses were documented by Doppler. Lower-extremity compartment pressures were measured and were most notable for an anterior pressure of 85 mm Hg, despite having received 12 vials of antivenin. Fasciotomy was deferred and the patient received two additional six-vial doses of antivenin to achieve local control. Compartment pressures improved with a 2.2-cm mean decrease in limb diameter within 48 h. Maintenance dosing was initiated and the patient ultimately received a total of 26 vials of antivenin. The patient did not develop significant coagulopathy or thrombocytopenia. Swelling continued to improve with return of limb function. In this case, early and aggressive treatment with antivenin may have avoided invasive fasciotomy, and its use should be considered in patients with copperhead envenomation and significantly elevated compartment pressures. Copyright © 2014 Elsevier Inc. All rights reserved.

Muzzle size, paranasal swelling size and body mass in Mandrillus leucophaeus.

PubMed

Elton, Sarah; Morgan, Bethan J

2006-04-01

The drill (Mandrillus leucophaeus), a forest-living Old World monkey, is highly sexually dimorphic, with males exhibiting extreme secondary sexual characteristics, including growth of paranasal swellings on the muzzle. In this study, the size of the secondary bone that forms the paranasal swellings on the muzzles of drills was assessed in relation to body mass proxies. The relationship between the overall size of the muzzle and surrogate measures of body mass was also examined. In female drills, muzzle breadth was positively correlated with two proxies of overall body mass, greatest skull length and upper M1 area. However, there was no such correlation in males. Paranasal swellings in males also appeared to have no significant relationship to body mass proxies. This suggests that secondary bone growth on the muzzles of male drills is independent of overall body size. Furthermore, this secondary bone appears to be vermiculate, probably developing rapidly and in an irregular manner, with no correlation in the sizes of paranasal swelling height and breadth. However, various paranasal swelling dimensions were related to the size of the muzzle. It is suggested that the growth of the paranasal swellings and possibly the muzzle could be influenced by androgen production and reflect testes size and sperm motility. The size and appearance of the paranasal swellings may thus be an indicator of reproductive quality both to potential mates and male competitors. Further work is required to investigate the importance of the paranasal swellings as secondary sexual characteristics in Mandrillus and the relationship between body size and secondary sexual characteristics. Attention should also be paid to the mechanisms and trajectories of facial growth in Mandrillus.

Non-monotonic swelling of surface grafted hydrogels induced by pH and/or salt concentration

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

Longo, Gabriel S.; Department of Biomedical Engineering, Northwestern University, Evanston, Illinois 60208; Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois 60208

2014-09-28

We use a molecular theory to study the thermodynamics of a weak-polyacid hydrogel film that is chemically grafted to a solid surface. We investigate the response of the material to changes in the pH and salt concentration of the buffer solution. Our results show that the pH-triggered swelling of the hydrogel film has a non-monotonic dependence on the acidity of the bath solution. At most salt concentrations, the thickness of the hydrogel film presents a maximum when the pH of the solution is increased from acidic values. The quantitative details of such swelling behavior, which is not observed when themore » film is physically deposited on the surface, depend on the molecular architecture of the polymer network. This swelling-deswelling transition is the consequence of the complex interplay between the chemical free energy (acid-base equilibrium), the electrostatic repulsions between charged monomers, which are both modulated by the absorption of ions, and the ability of the polymer network to regulate charge and control its volume (molecular organization). In the absence of such competition, for example, for high salt concentrations, the film swells monotonically with increasing pH. A deswelling-swelling transition is similarly predicted as a function of the salt concentration at intermediate pH values. This reentrant behavior, which is due to the coupling between charge regulation and the two opposing effects triggered by salt concentration (screening electrostatic interactions and charging/discharging the acid groups), is similar to that found in end-grafted weak polyelectrolyte layers. Understanding how to control the response of the material to different stimuli, in terms of its molecular structure and local chemical composition, can help the targeted design of applications with extended functionality. We describe the response of the material to an applied pressure and an electric potential. We present profiles that outline the local chemical composition of the hydrogel, which can be useful information when designing applications that pursue or require the absorption of biomolecules or pH-sensitive molecules within different regions of the film.« less

Synthesis and characterization of psyllium-NVP based drug delivery system through radiation crosslinking polymerization

NASA Astrophysics Data System (ADS)

Singh, Baljit; Kumar, S.

2008-08-01

In order to develop the hydrogels meant for the drug delivery, we have prepared psyllium- N-vinylpyrrolidone (NVP) based hydrogels by radiation induced crosslinking. Polymers were characterized with SEMs, FTIR and swelling studies. Swelling of the hydrogels was studied as a function of monomer concentration, total radiation dose, temperature, pH and [NaCl] of the swelling medium. The swelling kinetics of the hydrogels and release dynamics of anticancer model drug (5-fluorouracil) from the hydrogels have been carried out for the evaluation of swelling and drug release mechanism. It has been observed that diffusion exponent ' n' have 0.8, 0.9, 0.8 and gel characteristics constant ' k' have 9.22 × 10 -3, 2.06 × 10 -3, 11.72 × 10 -3 values for the release of drug from the drug loaded hydrogels in distilled water, pH 2.2 buffer and pH 7.4 buffer, respectively. The present study shows that the release of drug from the hydrogels occurred through Non-Fickian diffusion mechanism.

Intracanalicular Optic Nerve Swelling and Signal Change in Fulminant Untreated Idiopathic Intracranial Hypertension

PubMed Central

Moodley, Anand A.; Dlwati, Mahlubonke S.; Durand, Miranda

2017-01-01

ABSTRACT The role of the optic canal in the pathogenesis of papilloedema has been under scrutiny recently. Whether a larger canal precedes more severe papilloedema or is the result of bone remodelling from chronically raised pressure across a pressure gradient is not clear. The authors present the magnetic resonance imaging findings of a 29-year-old female with fulminant and untreated idiopathic intracranial hypertension. Imaging showed focal expansion and intrinsic signal changes of the intracanalicular optic nerve. The authors discuss the possibility of either fluid accumulation within the optic nerves from a water hammer effect across blocked optic canals resulting from the steep pressure gradient or opticomalacia (optic nerve softening) from chronic ischaemia. PMID:28348630

A novel multiphysic model for simulation of swelling equilibrium of ionized thermal-stimulus responsive hydrogels

NASA Astrophysics Data System (ADS)

Li, Hua; Wang, Xiaogui; Yan, Guoping; Lam, K. Y.; Cheng, Sixue; Zou, Tao; Zhuo, Renxi

2005-03-01

In this paper, a novel multiphysic mathematical model is developed for simulation of swelling equilibrium of ionized temperature sensitive hydrogels with the volume phase transition, and it is termed the multi-effect-coupling thermal-stimulus (MECtherm) model. This model consists of the steady-state Nernst-Planck equation, Poisson equation and swelling equilibrium governing equation based on the Flory's mean field theory, in which two types of polymer-solvent interaction parameters, as the functions of temperature and polymer-network volume fraction, are specified with or without consideration of the hydrogen bond interaction. In order to examine the MECtherm model consisting of nonlinear partial differential equations, a meshless Hermite-Cloud method is used for numerical solution of one-dimensional swelling equilibrium of thermal-stimulus responsive hydrogels immersed in a bathing solution. The computed results are in very good agreements with experimental data for the variation of volume swelling ratio with temperature. The influences of the salt concentration and initial fixed-charge density are discussed in detail on the variations of volume swelling ratio of hydrogels, mobile ion concentrations and electric potential of both interior hydrogels and exterior bathing solution.

An investigation on "nano-swelling" phenomenon during resist dissolution using in situ high-speed atomic force microscopy

NASA Astrophysics Data System (ADS)

Santillan, Julius Joseph; Itani, Toshiro

2017-03-01

This work focuses on the application of a high-speed atomic force microscope (HS-AFM) for the in situ observation / quantification of the resist dissolution process. Specifically, this paper discusses on the existence of what the authors refer to as "nano-swelling" which occurs in the extreme ultraviolet (EUV) exposed areas of a positive-tone chemically amplified resist, just before it dissolves into the aqueous tetramethylammonium hydroxide (TMAH) developer solution. In earlier experiments using typical EUVL resist materials (e.g. polyhydroxystyrene (PHS) polymer and hybrid PHS-methacryl polymer model resists), it was understood that nano-swelling is mainly material type-dependent. As shown in the investigations/results in this paper, nano-swelling has variations in the timing of occurrence and amount/size depending on the size of the dissolvable areas (i.e. larger dissolvable areas dissolve faster, swell more compared to smaller ones). Lastly, a comparison of surface analyses results of a resist pattern before, during, and after the occurrence of nano-swelling suggests the significant impact of these kinds of non-uniformities in the formation of line edge/line width roughness (LER/LWR).

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

Liang, Linyun; Mei, Zhi-Gang; Yacout, Abdellatif M.

We have developed a mesoscale phase-field model for studying the effect of recrystallization on the gas-bubble-driven swelling in irradiated U-Mo alloy fuel. The model can simulate the microstructural evolution of the intergranular gas bubbles on the grain boundaries as well as the recrystallization process. Our simulation results show that the intergranular gas-bubble-induced fuel swelling exhibits two stages: slow swelling kinetics before recrystallization and rapid swelling kinetics with recrystallization. We observe that the recrystallization can significantly expedite the formation and growth of gas bubbles at high fission densities. The reason is that the recrystallization process increases the nucleation probability of gasmore » bubbles and reduces the diffusion time of fission gases from grain interior to grain boundaries by increasing the grain boundary area and decreasing the diffusion distance. The simulated gas bubble shape, size distribution, and density on the grain boundaries are consistent with experimental measurements. We investigate the effect of the recrystallization on the gas-bubble-driven fuel swelling in UMo through varying the initial grain size and grain aspect ratio. We conclude that the initial microstructure of fuel, such as grain size and grain aspect ratio, can be used to effectively control the recrystallization and therefore reduce the swelling in U-Mo fuel.« less

A Finite Element Model for Mixed Porohyperelasticity with Transport, Swelling, and Growth.

PubMed

Armstrong, Michelle Hine; Buganza Tepole, Adrián; Kuhl, Ellen; Simon, Bruce R; Vande Geest, Jonathan P

2016-01-01

The purpose of this manuscript is to establish a unified theory of porohyperelasticity with transport and growth and to demonstrate the capability of this theory using a finite element model developed in MATLAB. We combine the theories of volumetric growth and mixed porohyperelasticity with transport and swelling (MPHETS) to derive a new method that models growth of biological soft tissues. The conservation equations and constitutive equations are developed for both solid-only growth and solid/fluid growth. An axisymmetric finite element framework is introduced for the new theory of growing MPHETS (GMPHETS). To illustrate the capabilities of this model, several example finite element test problems are considered using model geometry and material parameters based on experimental data from a porcine coronary artery. Multiple growth laws are considered, including time-driven, concentration-driven, and stress-driven growth. Time-driven growth is compared against an exact analytical solution to validate the model. For concentration-dependent growth, changing the diffusivity (representing a change in drug) fundamentally changes growth behavior. We further demonstrate that for stress-dependent, solid-only growth of an artery, growth of an MPHETS model results in a more uniform hoop stress than growth in a hyperelastic model for the same amount of growth time using the same growth law. This may have implications in the context of developing residual stresses in soft tissues under intraluminal pressure. To our knowledge, this manuscript provides the first full description of an MPHETS model with growth. The developed computational framework can be used in concert with novel in-vitro and in-vivo experimental approaches to identify the governing growth laws for various soft tissues.

A Finite Element Model for Mixed Porohyperelasticity with Transport, Swelling, and Growth

PubMed Central

Armstrong, Michelle Hine; Buganza Tepole, Adrián; Kuhl, Ellen; Simon, Bruce R.; Vande Geest, Jonathan P.

2016-01-01

The purpose of this manuscript is to establish a unified theory of porohyperelasticity with transport and growth and to demonstrate the capability of this theory using a finite element model developed in MATLAB. We combine the theories of volumetric growth and mixed porohyperelasticity with transport and swelling (MPHETS) to derive a new method that models growth of biological soft tissues. The conservation equations and constitutive equations are developed for both solid-only growth and solid/fluid growth. An axisymmetric finite element framework is introduced for the new theory of growing MPHETS (GMPHETS). To illustrate the capabilities of this model, several example finite element test problems are considered using model geometry and material parameters based on experimental data from a porcine coronary artery. Multiple growth laws are considered, including time-driven, concentration-driven, and stress-driven growth. Time-driven growth is compared against an exact analytical solution to validate the model. For concentration-dependent growth, changing the diffusivity (representing a change in drug) fundamentally changes growth behavior. We further demonstrate that for stress-dependent, solid-only growth of an artery, growth of an MPHETS model results in a more uniform hoop stress than growth in a hyperelastic model for the same amount of growth time using the same growth law. This may have implications in the context of developing residual stresses in soft tissues under intraluminal pressure. To our knowledge, this manuscript provides the first full description of an MPHETS model with growth. The developed computational framework can be used in concert with novel in-vitro and in-vivo experimental approaches to identify the governing growth laws for various soft tissues. PMID:27078495

Dart model for irradiation-induced swelling of dispersion fuel elements including aluminum-fuel interaction

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

Rest, J.; Hofman, G.L.

1997-06-01

The Dispersion Analysis Research Tool (DART) contains models for fission-gas induced fuel swelling, interaction of fuel with the matrix aluminum, resultant reaction-product swelling, and calculation of the stress gradient within the fuel particle. The effects of an aluminide shell on fuel particle swelling are evaluated. Validation of the model is demonstrated by a comparison of DART calculations of fuel swelling of U{sub 3}SiAl-Al and U{sub 3}Si{sub 2}-Al for various dispersion fuel element designs with the data. DART results are compared with data for fuel swelling Of U{sub 3}SiAl-Al in plate, tube, and rod configurations as a function of fission density.more » Plate and tube calculations were performed at a constant fuel temperature of 373 K and 518 K, respectively. An irradiation temperature of 518 K results in a calculated aluminide layer thickness for the Russian tube that is in the center of the measured range (16 {mu}m). Rod calculations were performed with a temperature gradient across the rod characterized by surface and central temperatures of 373 K and 423 K, respectively. The effective yield stress of irradiated Al matrix material and the aluminide was determined by comparing the results of DART calculations with postirradiation immersion volume measurement of U{sub 3}SiAl plates. The values for the effective yield stress were used in all subsequent simulations. The lower calculated fuel swelling in the rod-type element is due to an assumed biaxial stress state. Fuel swelling in plates results in plate thickness increase only. Likewise, in tubes, only the wall thickness increases. Irradiation experiments have shown that plate-type dispersion fuel elements can develop blisters or pillows at high U-235 burnup when fuel compounds exhibiting breakaway swelling are used at moderate to high fuel volume fractions. DART-calculated interaction layer thickness and fuel swelling follows the trends of the observations. 3 refs., 2 figs.« less

Decay and termite resistance, water absorption and swelling of thermally compressed wood panels

Treesearch

Oner Unsal; S. Nami Kartal; Zeki Candan; Rachel A. Arango; Carol A. Clausen; Frederick Green

2009-01-01

This study evaluated decay and termite resistance of thermally compressed pine wood panels under pressure at either 5 or 7 MPa and either 120 or 150 °C for 1 h. Wood specimens from the panels were exposed to laboratory decay resistance by using the wood degrading fungi, Gloeophyllum trabeum and Trametes versicolor. The thermal compression process caused increases in...

Infrasound-induced hemodynamics, ultrastructure, and molecular changes in the rat myocardium.

PubMed

Pei, Zhaohui; Sang, Hanfei; Li, Ruiman; Xiao, Pingxi; He, Jiangui; Zhuang, Zhiqiang; Zhu, Miaozhang; Chen, Jingzao; Ma, Hong

2007-04-01

Recent interest in adverse effects of infrasound on organisms arises from health concerns. We assessed the association between infrasound exposure of 5 Hz at 130 dB and changes of cardiac ultrastructure and function in rats. Thirty-two Sprague-Dawley rats were randomized into control, 1, 7, and 14 days groups for 2 h of infrasound once daily according to planned schedules. Changes of cardiac ultrastructure, hemodynamics indices, intracellular Ca(2+) concentrations ([Ca(2+)](i)), and sarcoplasmic reticulum Ca(2+)-ATPase 2 (SERCA2) were detected. Heart rates in 1 day group were significantly increased compared with control group and no significant changes in other groups. Left ventricular systolic pressures were significantly increased with time. Left ventricular diastolic end pressure and maximum rising rates of left ventricular pressure (+dl/dt) were significantly increased in 7 and 14 days groups and not changed in 1 day group, compared with control group. Maximum dropping rates of left ventricular pressure (-dl/dt) were significantly decreased in 7 and 14 days groups and not changed in 1 day group, compared with control group. In heart cells, there were several swelled mitochondria in 1 day group, more swelled mitochondria in 7 days group, platelet aggregation in the intercellular substance in 14 days group. [Ca(2+)](i) were significantly increased with time. There was a significant increase in SERCA2 in 1 day group, while a significant decrease in 7 and 14 days groups, compared with control group. Infrasound of 5 Hz at 130 dB can damage cardiac ultrastructure and function. Changes of [Ca(2+)](i) and SERCA2 play an important role in the secondary cardiac damage. (c) 2007 Wiley Periodicals, Inc.

Release of Water Soluble Drugs from Dynamically Swelling POLY(2-HYDROXYETHYL Methacrylate - CO - Methacrylic Acid) Hydrogels.

NASA Astrophysics Data System (ADS)

Kou, Jim Hwai-Cher

In this study, ionizable copolymers of HEMA and methacrylic acid (MA) are investigated for their potential use in developing pH dependent oral delivery systems. Because of the MA units, these gels swell extensively at high pH. Since solute diffusion in the hydrophilic polymers depends highly on the water content of the matrix, it is anticipated that the release rate will be modulated by this pH induced swelling. From a practical point of view, the advantage of the present system is that one can minimize drug loss in the stomach and achieve a programmed release in intestine. This approach is expected to improve delivery of acid labile drugs or drugs that cause severe gastrointestinal side effects. This work mainly focuses on the basic understanding of the mechanism involved in drug release from the poly(HEMA -co- MA) gels, especially under dynamic swelling conditions. Equilibrium swelling is first characterized since water content is the major determinant of transport properties in these gels. Phenylpropanolamine (PPA) is chosen as the model drug for the release study and its diffusion characteristics in the gel matrix determined. The data obtained show that the PPA diffusivity follows the free volume theory of Yasuda, which explains the accelerating effect of swelling on drug release. A mathematical model based on a diffusion mechanism has been developed to describe PPA release from the swelling gels. Based on this model, several significant conclusions can be drawn. First, the release rate can be modulated by the aspect ratio of the cylindrical geometry, and this has a practical implication in dosage form design. Second, the release rate can be lowered quite considerably if the dimensional increase due to swelling is significant. Consequently, it is the balance between the drug diffusivity increase and the gel dimensional growth that determines the release rate from the swelling matrix. Third, quasi-steady release kinetics, which are characteristic of swelling release systems, can also be predicted by this model. PPA release from initially dry poly(HEMA -co- MA) gels has also been studied. The data show that the release rate is mainly controlled by the PPA loading level and quite insensitive to the methacrylic acid composition of the gels. These phenomena can be adequately explained by analyzing the transport resistances in the gels. The overall time scale of release from these gels were shown to be in the range which was suitable for oral controlled release applications. (Abstract shortened with permission of author.).

Optical scatter imaging of cellular and mitochondrial swelling in brain tissue models of stroke

NASA Astrophysics Data System (ADS)

Johnson, Lee James

2001-08-01

The severity of brain edema resulting from a stroke can determine a patient's survival and the extent of their recovery. Cellular swelling is the microscopic source of a significant part of brain edema. Mitochondrial swelling also appears to be a determining event in the death or survival of the cells that are injured during a stroke. Therapies for reducing brain edema are not effective in many cases and current treatments of stroke do not address mitochondrial swelling at all. This dissertation is motivated by the lack of a complete understanding of cellular swelling resulting from stroke and the lack of a good method to begin to study mitochondrial swelling resulting from stroke in living brain tissue. In this dissertation, a novel method of detecting mitochondrial and cellular swelling in living hippocampal slices is developed and validated. The system is used to obtain spatial and temporal information about cellular and mitochondrial swelling resulting from various models of stroke. The effect of changes in water content on light scatter and absorption are examined in two models of brain edema. The results of this study demonstrate that optical techniques can be used to detect changes in water content. Mie scatter theory, the theoretical basis of the dual- angle scatter ratio imaging system, is presented. Computer simulations based on Mie scatter theory are used to determine the optimal angles for imaging. A detailed account of the early systems is presented to explain the motivations for the system design, especially polarization, wavelength and light path. Mitochondrial sized latex particles are used to determine the system response to changes in scattering particle size and concentration. The dual-angle scatter ratio imaging system is used to distinguish between osmotic and excitotoxic models of stroke injury. Such distinction cannot be achieved using the current techniques to study cellular swelling in hippocampal slices. The change in the scatter ratio is then shown to correlate to mitochondrial swelling, as observed with electron microscopy. The system is finally used to study mitochondrial and cellular swelling. Evidence of the susceptibility of certain hippocampal regions, CA1 and the dentate gyrus, to exhibit mitochondrial swelling as the result of oxygen and glucose deprivation is presented. In addition, for the first time, the time course of mitochondrial swelling is seen. Finally, experiments with scatter imaging and measurement of nitric oxide with carbon fiber electrodes demonstrate a clear link between nitric oxide and cellular swelling. A potential mechanism of the action of nitric oxide is evaluated. Nitric oxide appears to act to cause cellular swelling without the release of glutamate. The use of targeted nitric oxide inhibitors may be useful for the reduction of edema.

AKT activation promotes PTEN hamartoma tumor syndrome–associated cataract development

PubMed Central

Sellitto, Caterina; Li, Leping; Gao, Junyuan; Robinson, Michael L.; Lin, Richard Z.; Mathias, Richard T.; White, Thomas W.

2013-01-01

Mutations in the human phosphatase and tensin homolog (PTEN) gene cause PTEN hamartoma tumor syndrome (PHTS), which includes cataract development among its diverse clinical pathologies. Currently, it is not known whether cataract formation in PHTS patients is secondary to other systemic problems, or the result of the loss of a critical function of PTEN within the lens. We generated a mouse line with a lens-specific deletion of Pten (PTEN KO) and identified a regulatory function for PTEN in lens ion transport. Specific loss of PTEN in the lens resulted in cataract. PTEN KO lenses exhibited a progressive age-related increase in intracellular hydrostatic pressure, along with, increased intracellular sodium concentrations, and reduced Na+/K+-ATPase activity. Collectively, these defects lead to lens swelling, opacities and ultimately organ rupture. Activation of AKT was highly elevated in PTEN KO lenses compared to WT mice. Additionally, pharmacological inhibition of AKT restored normal Na+/K+-ATPase activity in primary cultured lens cells and reduced lens pressure in intact lenses from PTEN KO animals. These findings identify a direct role for PTEN in the regulation of lens ion transport through an AKT-dependent modulation of Na+/K+-ATPase activity, and provide a new animal model to investigate cataract development in PHTS patients. PMID:24270425

Preparation and physico-chemical properties of hydrogels from carboxymethyl cassava starch crosslinked with citric acid

NASA Astrophysics Data System (ADS)

Boonkham, Sasikan; Sangseethong, Kunruedee; Chatakanon, Pathama; Niamnuy, Chalida; Nakasaki, Kiyohiko; Sriroth, Klanarong

2014-06-01

Recently, environmentally friendly hydrogels prepared from renewable bio-based resources have drawn significant attention from both industrial and academic sectors. In this study, chemically crosslinked hydrogels have been developed from cassava starch which is a bio-based polymer using a non-toxic citric acid as a crosslinking agent. Cassava starch was first modified by carboxymethylation to improve its water absorbency property. The carboxymethyl cassava starch (CMCS) obtained was then crosslinked with citric acid at different concentrations and reaction times. The gel fraction of hydrogels increased progressively with increasing citric acid concentration. Free swelling capacity of hydrogels in de-ionized water, saline solution and buffers at various pHs as well as absorption under load were investigated. The results revealed that swelling behavior and mechanical characteristic of hydrogels depended on the citric acid concentration used in reaction. Increasing citric acid concentration resulted in hydrogels with stronger network but lower swelling and absorption capacity. The cassava starch hydrogels developed were sensitive to ionic strength and pH of surrounding medium, showing much reduced swelling capacity in saline salt solution and acidic buffers.

In vivo optophysiology reveals that G-protein activation triggers osmotic swelling and increased light scattering of rod photoreceptors.

PubMed

Zhang, Pengfei; Zawadzki, Robert J; Goswami, Mayank; Nguyen, Phuong T; Yarov-Yarovoy, Vladimir; Burns, Marie E; Pugh, Edward N

2017-04-04

The light responses of rod and cone photoreceptors have been studied electrophysiologically for decades, largely with ex vivo approaches that disrupt the photoreceptors' subretinal microenvironment. Here we report the use of optical coherence tomography (OCT) to measure light-driven signals of rod photoreceptors in vivo. Visible light stimulation over a 200-fold intensity range caused correlated rod outer segment (OS) elongation and increased light scattering in wild-type mice, but not in mice lacking the rod G-protein alpha subunit, transducin (Gα t ), revealing these responses to be triggered by phototransduction. For stimuli that photoactivated one rhodopsin per Gα t the rod OS swelling response reached a saturated elongation of 10.0 ± 2.1%, at a maximum rate of 0.11% s -1 Analyzing swelling as osmotically driven water influx, we find the H 2 O membrane permeability of the rod OS to be (2.6 ± 0.4) × 10 -5 cm⋅s -1 , comparable to that of other cells lacking aquaporin expression. Application of Van't Hoff's law reveals that complete activation of phototransduction generates a potentially harmful 20% increase in OS osmotic pressure. The increased backscattering from the base of the OS is explained by a model combining cytoplasmic swelling, translocation of dissociated G-protein subunits from the disc membranes into the cytoplasm, and a relatively higher H 2 O permeability of nascent discs in the basal rod OS. Translocation of phototransduction components out of the OS may protect rods from osmotic stress, which could be especially harmful in disease conditions that affect rod OS structural integrity.

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

Bhattacharya, Arunodaya; Meslin, Estelle; Henry, Jean

Effect of helium on void swelling was studied in high-purity α-iron, irradiated using energetic self-ions to 157 displacements per atom (dpa) at 773 K, with and without helium co-implantation up to 17 atomic parts-per-million (appm) He/dpa. Helium is known to enhance cavity formation in metals in irradiation environments, leading to early void swelling onset. In this study, microstructure characterization by transmission electron microscopy revealed compelling evidence of dramatic swelling reduction by helium co-implantation, achieved primarily by cavity size reduction. In conclusion, a comprehensive understanding of helium induced cavity microstructure development is discussed using sink strength ratios of dislocations and cavities.

Orbital necrotizing fasciitis and osteomyelitis caused by arcanobacterium haemolyticum: a case report.

PubMed

Stone, Lindsay A; Harshbarger, Raymond J

2015-01-01

The facial region is infrequently affected by necrotizing infections. Orbital necrotizing infections are even rarer, seen following trauma, local skin infection, and sinusitis. The authors report a unique case of orbital necrotizing fasciitis and osteomyelitis resulting from Arcanobacterium Haemolyticum ethmoid sinusitis. No prior occurrences of Arcanobacterial species orbital necrotizing fasciitis/osteomyelitis have been reported.A 16-year-old boy presented to the ER with a 3-day history of fever, chills, headache, and sinus pressure. CT scan revealed soft tissue swelling of the right orbit, forehead, and ethmoid sinusitis. Within 24 hours of admission, he suffered rapidly progressive swelling and erythema of the right orbit and forehead with diminished visual acuity, despite broad-spectrum antibiotics. Orbital exploration revealed frankly necrotic fascia and periosteum along the superior aspect. Lateral canthotomy, cantholysis, decompression of the optic nerve, and soft tissue debridement with bone biopsy was performed. Operative specimens isolated Arcanobacterium Haemolyticum. Pathologic examination revealed right orbital osteomyelitis.

Geophysics and Nanosciences: Nano to Micro to Meso to Macro Scale Swelling Soils

NASA Astrophysics Data System (ADS)

Cushman, J.

2003-04-01

We use statistical mechanical simulations of nanoporous materials to motivate a choice of independent constitutive variables for a multiscale mixture theory of swelling soils. A video will illustrate the structural behavior of fluids in nanopores when they are adsorbed from a bulk phase vapor to form capillaries on the nanoscale. These simulations suggest that when a swelling soil is very dry, the full strain tensor for the liquid phase should be included in the list of independent variables in any mixture theory. We use this information to develop a three-scale (micro, meso, macro) mixture theory for swelling soils. For a simplified case, we present the underlying multiscale field equations and constitutive theory, solve the resultant well posed system numerically, and present some graphical results for a drying and shrinking body.

Braking, Wheeled Vehicles. Test Operations Procedure (TOP)

DTIC Science & Technology

2008-05-20

actuated. 2. Hydraulic System Procedure: Visually inspect the lines, hoses , master cylinder and cap. Reject the vehicle if: • Lines and... hoses are leaking, welded, cracked, chafed, flattened, insecurely mounted or have restricted sections. • Repairs to lines and hoses have been made...608 20 May 2008 D-3 HAZARDOUS CONDITION • Any brake hose or line seeps or swells under pressure. • Any brake hose is cracked to the second

Efficiency of a borehole seal by means of pre-compacted bentonite blocks

NASA Astrophysics Data System (ADS)

Van Geet, M.; Volckaert, G.; Bastiaens, W.; Maes, N.; Weetjens, E.; Sillen, X.; Vallejan, B.; Gens, A.

The backfilling and sealing of shafts and galleries is an essential part of the design of underground repositories for high-level radioactive waste. Part of the EC funded project RESEAL studied the feasibility of sealing off a borehole in plastic Boom Clay by means of pre-compacted bentonite blocks. Two bentonites, namely the FoCa and Serrata clay, have been used. Based on laboratory tests, the bentonite blocks had an initial dry density of about 1.8 g/cm 3 to obtain a swelling pressure of about 4.4 MPa, corresponding to the in situ lithostatic stress, at full saturation. The set-up was equipped with several sensors to follow-up the behaviour of the seal and the surrounding host rock during hydration. Full saturation was reached after five months and was mainly reached by natural hydration. Swelling pressure was lower than originally foreseen due to the slow reconsolidation of the host rock. Later on, the efficiency of the seal with respect to water, gas and radionuclide migration was tested. The in situ measured permeability of the seals was about 5 × 10 -13 m/s. A gas breakthrough experiment did not show any preferential gas migration through the seal. No evidences of a preferential pathway could be detected from 125I tracer test results.

Soft mechanical metamaterials with unusual swelling behavior and tunable stress-strain curves

PubMed Central

Guo, Xiaogang; Wu, Jun

2018-01-01

Soft adaptable materials that change their shapes, volumes, and properties in response to changes under ambient conditions have important applications in tissue engineering, soft robotics, biosensing, and flexible displays. Upon water absorption, most existing soft materials, such as hydrogels, show a positive volume change, corresponding to a positive swelling. By contrast, the negative swelling represents a relatively unusual phenomenon that does not exist in most natural materials. The development of material systems capable of large or anisotropic negative swelling remains a challenge. We combine analytic modeling, finite element analyses, and experiments to design a type of soft mechanical metamaterials that can achieve large effective negative swelling ratios and tunable stress-strain curves, with desired isotropic/anisotropic features. This material system exploits horseshoe-shaped composite microstructures of hydrogel and passive materials as the building blocks, which extend into a periodic network, following the lattice constructions. The building block structure leverages a sandwiched configuration to convert the hydraulic swelling deformations of hydrogel into bending deformations, thereby resulting in an effective shrinkage (up to around −47% linear strain) of the entire network. By introducing spatially heterogeneous designs, we demonstrated a range of unusual, anisotropic swelling responses, including those with expansion in one direction and, simultaneously, shrinkage along the perpendicular direction. The design approach, as validated by experiments, allows the determination of tailored microstructure geometries to yield desired length/area changes. These design concepts expand the capabilities of existing soft materials and hold promising potential for applications in a diverse range of areas.

Study on dissolution behavior of polymer-bound and polymer-blended photo-acid generator (PAG) resists

NASA Astrophysics Data System (ADS)

Yamamoto, Hiroki; Kozawa, Takahiro; Tagawa, Seiichi

2013-03-01

The requirements for the next generation resist materials are so challenging that it is indispensable for feasibility of EUV lithography to grasp basic chemistry of resist matrices in all stage of resist processes. Under such circumstances, it is very important to know dissolution characteristics of the resist film into alkaline developer though the dissolution of exposed area of resist films in alkaline developer to form a pattern is a complex reactive process. In this study, the influence of EUV and KrF exposure on the dissolution behavior of polymer bound PAG and polymer blended PAG was studied in detail using quartz crystal microbalance (QCM) methods. The difference in swelling formation between KrF and EUV exposure was observed. It is likely that difference of reaction mechanism induces the difference of these swelling. Also, it is observed that the swelling of polymer-bound PAG is less than that of polymer blended PAG in both KrF and EUV exposure. This result indicates that polymer-bound PAG suppresses swelling very well and showed an excellent performance. Actually, the developed polymer bound-PAG resist showed an excellent performance (half pitch 50 nm line and space pattern). Thus, polymer bound PAG is one of the promising candidate for 16 nm EUV resist.

The Influence of Fracturing Fluids on Fracturing Processes: A Comparison Between Water, Oil and SC-CO2

NASA Astrophysics Data System (ADS)

Wang, Jiehao; Elsworth, Derek; Wu, Yu; Liu, Jishan; Zhu, Wancheng; Liu, Yu

2018-01-01

Conventional water-based fracturing treatments may not work well for many shale gas reservoirs. This is due to the fact that shale gas formations are much more sensitive to water because of the significant capillary effects and the potentially high contents of swelling clay, each of which may result in the impairment of productivity. As an alternative to water-based fluids, gaseous stimulants not only avoid this potential impairment in productivity, but also conserve water as a resource and may sequester greenhouse gases underground. However, experimental observations have shown that different fracturing fluids yield variations in the induced fracture. During the hydraulic fracturing process, fracturing fluids will penetrate into the borehole wall, and the evolution of the fracture(s) then results from the coupled phenomena of fluid flow, solid deformation and damage. To represent this, coupled models of rock damage mechanics and fluid flow for both slightly compressible fluids and CO2 are presented. We investigate the fracturing processes driven by pressurization of three kinds of fluids: water, viscous oil and supercritical CO2. Simulation results indicate that SC-CO2-based fracturing indeed has a lower breakdown pressure, as observed in experiments, and may develop fractures with greater complexity than those developed with water-based and oil-based fracturing. We explore the relation between the breakdown pressure to both the dynamic viscosity and the interfacial tension of the fracturing fluids. Modeling demonstrates an increase in the breakdown pressure with an increase both in the dynamic viscosity and in the interfacial tension, consistent with experimental observations.

Osmotic Engine: Translating Osmotic Pressure into Macroscopic Mechanical Force via Poly(Acrylic Acid) Based Hydrogels

PubMed Central

Arens, Lukas; Weißenfeld, Felix; Klein, Christopher O.; Schlag, Karin

2017-01-01

Poly(acrylic acid)‐based hydrogels can swell up to 100–1000 times their own weight in desalinated water due to osmotic forces. As the swelling is about a factor of 2–12 lower in seawater‐like saline solutions (4.3 wt% NaCl) than in deionized water, cyclic swelling, and shrinking can potentially be used to move a piston in an osmotic motor. Consequently, chemical energy is translated into mechanical energy. This conversion is driven by differences in chemical potential and by changes in entropy. This is special, as most thermodynamic engines rely instead on the conversion of heat into mechanical energy. To optimize the efficiency of this process, the degree of neutralization, the degree of crosslinking, and the particle size of the hydrogels are varied. Additionally, different osmotic engine prototypes are constructed. The maximum mean power of 0.23 W kg−1 dry hydrogel is found by using an external load of 6 kPa, a polymer with 1.7 mol% crosslinking, a degree of neutralization of 10 mol%, and a particle size of 370–670 µm. As this is achieved only in the first round of optimization, higher values of the maximum power average over one cycle seem realistic. PMID:28932675

Applying terahertz technology for nondestructive detection of crack initiation in a film-coated layer on a swelling tablet

PubMed Central

Momose, Wataru; Yoshino, Hiroyuki; Katakawa, Yoshifumi; Yamashita, Kazunari; Imai, Keiji; Sako, Kazuhiro; Kato, Eiji; Irisawa, Akiyoshi; Yonemochi, Etsuo; Terada, Katsuhide

2012-01-01

Here, we describe a nondestructive approach using terahertz wave to detect crack initiation in a film-coated layer on a drug tablet. During scale-up and scale-down of the film coating process, differences in film density and gaps between the film-coated layer and the uncoated tablet were generated due to differences in film coating process parameters, such as the tablet-filling rate in the coating machine, spray pressure, and gas–liquid ratio etc. Tablets using the PEO/PEG formulation were employed as uncoated tablets. We found that heat and humidity caused tablets to swell, thereby breaking the film-coated layer. Using our novel approach with terahertz wave nondestructively detect film surface density (FSD) and interface density differences (IDDs) between the film-coated layer and an uncoated tablet. We also found that a reduced FSD and IDD between the film-coated layer and uncoated tablet increased the risk of crack initiation in the film-coated layer, thereby enabling us to nondestructively predict initiation of cracks in the film-coated layer. Using this method, crack initiation can be nondestructively assessed in swelling tablets after the film coating process without conducting accelerated stability tests, and film coating process parameters during scale-up and scale-down studies can be appropriately established. PMID:25755992

Lymphatic System Flows

NASA Astrophysics Data System (ADS)

Moore, James E., Jr.; Bertram, Christopher D.

2018-01-01

The supply of oxygen and nutrients to tissues is performed by the blood system and involves a net leakage of fluid outward at the capillary level. One of the principal functions of the lymphatic system is to gather this fluid and return it to the blood system to maintain overall fluid balance. Fluid in the interstitial spaces is often at subatmospheric pressure, and the return points into the venous system are at pressures of approximately 20 cmH2O. This adverse pressure difference is overcome by the active pumping of collecting lymphatic vessels, which feature closely spaced one-way valves and contractile muscle cells in their walls. Passive vessel squeezing causes further pumping. The dynamics of lymphatic pumping have been investigated experimentally and mathematically, revealing complex behaviors that indicate that the system performance is robust against minor perturbations in pressure and flow. More serious disruptions can lead to incurable swelling of tissues called lymphedema.

Pressure wave injuries to rat dorsal root ganglion cells in culture caused by high-energy missiles.

PubMed

Suneson, A; Hansson, H A; Lycke, E; Seeman, T

1989-01-01

A high-energy missile impact in an extremity of an animal creates a shock wave which is rapidly dispersed as a burst of oscillating pressure waves that traverses the entire body causing local, regional, and distant injuries. The present study was performed on dorsal root ganglion (DRG) cells, cultured for 3 weeks, to elucidate the cellular mechanism for damage of nerve cells, using a simplified test system. A model system was developed allowing exposure of DRG cultures to a burst of high-frequency oscillating pressure waves, comparable to those recorded in animals after high-energy missile extremity impact. The pressure waves were induced by impact of a high-energy missile in a rubber tube filled with water, in which nerve cell cultures were kept in a closed rubber glove filled with tissue culture medium. The pressure waves had a duration of 0.5-1.5 ms and a frequency spectrum ranging from 0-250 kHz. Within minutes the neurites showed changes in their microtubules. In addition, varicosities, enriched with tubulin immunoreactive material, became irregularly studded along the nerve cell processes. Scattered DRG cells were initially permeable to the marker complex Evans-blue albumin (EBA), used as an indicator of the ability of the plasma membranes to exclude proteins. After 6 hr, however, almost every DRG neuron was intensely stained by EBA. Concomitantly, there was swelling of the nerve cell cytoplasm and organelles, and, to a variable extent, neurofilament tangles were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Formation of nanoscale networks: selectively swelling amphiphilic block copolymers with CO2-expanded liquids

NASA Astrophysics Data System (ADS)

Gong, Jianliang; Zhang, Aijuan; Bai, Hua; Zhang, Qingkun; Du, Can; Li, Lei; Hong, Yanzhen; Li, Jun

2013-01-01

Polymeric films with nanoscale networks were prepared by selectively swelling an amphiphilic diblock copolymer, polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP), with the CO2-expanded liquid (CXL), CO2-methanol. The phase behavior of the CO2-methanol system was investigated by both theoretical calculation and experiments, revealing that methanol can be expanded by CO2, forming homogeneous CXL under the experimental conditions. When treated with the CO2-methanol system, the spin cast compact PS-b-P4VP film was transformed into a network with interconnected pores, in a pressure range of 12-20 MPa and a temperature range of 45-60 °C. The formation mechanism of the network, involving plasticization of PS and selective swelling of P4VP, was proposed. Because the diblock copolymer diffusion process is controlled by the activated hopping of individual block copolymer chains with the thermodynamic barrier for moving PVP segments from one to another, the formation of the network structures is achieved in a short time scale and shows ``thermodynamically restricted'' character. Furthermore, the resulting polymer networks were employed as templates, for the preparation of polypyrrole networks, by an electrochemical polymerization process. The prepared porous polypyrrole film was used to fabricate a chemoresistor-type gas sensor which showed high sensitivity towards ammonia.Polymeric films with nanoscale networks were prepared by selectively swelling an amphiphilic diblock copolymer, polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP), with the CO2-expanded liquid (CXL), CO2-methanol. The phase behavior of the CO2-methanol system was investigated by both theoretical calculation and experiments, revealing that methanol can be expanded by CO2, forming homogeneous CXL under the experimental conditions. When treated with the CO2-methanol system, the spin cast compact PS-b-P4VP film was transformed into a network with interconnected pores, in a pressure range of 12-20 MPa and a temperature range of 45-60 °C. The formation mechanism of the network, involving plasticization of PS and selective swelling of P4VP, was proposed. Because the diblock copolymer diffusion process is controlled by the activated hopping of individual block copolymer chains with the thermodynamic barrier for moving PVP segments from one to another, the formation of the network structures is achieved in a short time scale and shows ``thermodynamically restricted'' character. Furthermore, the resulting polymer networks were employed as templates, for the preparation of polypyrrole networks, by an electrochemical polymerization process. The prepared porous polypyrrole film was used to fabricate a chemoresistor-type gas sensor which showed high sensitivity towards ammonia. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr33188h

Investigating the effect of processing parameters on pharmaceutical tablet disintegration using a real-time particle imaging approach.

PubMed

Rajkumar, Arthi D; Reynolds, Gavin K; Wilson, David; Wren, Stephen; Hounslow, Michael J; Salman, Agba D

2016-09-01

Tablet disintegration is a fundamental parameter that is tested in vitro before a product is released to the market, to give confidence that the tablet will break up in vivo and that active drug will be available for absorption. Variations in tablet properties cause variation in disintegration behaviour. While the standardised pharmacopeial disintegration test can show differences in the speed of disintegration of different tablets, it does not give any mechanistic information about the underlying cause of the difference. With quantifiable disintegration data, and consequently an improved understanding into tablet disintegration, a more knowledge-based approach could be applied to the research and development of future tablet formulations. The aim of the present research was to introduce an alternative method which will enable a better understanding of tablet disintegration using a particle imaging approach. A purpose-built flow cell was employed capable of online observation of tablet disintegration, which can provide information about the changing tablet dimensions and the particles released with time. This additional information can improve the understanding of how different materials and process parameters affect tablet disintegration. Standard USP analysis was also carried out to evaluate and determine whether the flow cell method can suitably differentiate the disintegration behaviour of tablets produced using different processing parameters. Placebo tablets were produced with varying ratios of insoluble and soluble filler (mannitol and MCC, respectively) so that the effect of variation in the formulation can be investigated. To determine the effect of the stress applied during granulation and tableting on tablet disintegration behaviour, analysis was carried out on tablets produced using granular material compressed at 20 or 50bar, where a tableting load of either 15 or 25kN was used. By doing this the tablet disintegration was examined in terms of the tablet porosity by monitoring the tablet area and particle release. It was found that when 20 and 50bar roller compaction pressure was used the USP analysis showed almost identical disintegration times for the consequent tablets. With the flow cell method a greater tablet swelling was observed for the lower pressure followed by steady tablet erosion. Additionally, more particles were released during disintegration due to the smaller granule size distribution within the tablet. When a higher tableting pressure was applied the tablet exhibited a delay in the time taken to reach the maximum swelling area, and slower tablet erosion and particle release were also observed, largely due to the tablet being much denser causing slower water uptake. This was in agreement with the USP analysis data. Overall it was confirmed by using both the standard USP analysis and flow cell method that the tablet porosity affects the tablet disintegration, whereby a more porous tablet disintegrates more slowly. But a more in-depth understanding was obtained using the flow cell method as it was determined that tablets will swell to varying degrees and release particles at different rates depending on the roller compaction and tableting pressure used. Copyright © 2016 Elsevier B.V. All rights reserved.

Charge-regularized swelling kinetics of polyelectrolyte gels

NASA Astrophysics Data System (ADS)

Sen, Swati; Kundagrami, Arindam

The swelling kinetics of polyelectrolyte gels with fixed and variable degrees of ionization in salt-free solvent is studied by solving the constitutive equation of motion of the spatially and temporally varying displacement variable. Two methods for the swelling kinetics - the Bulk Modulus Method (BMM), which uses a linear stress-strain relationship (and, hence a bulk modulus), and the Stress Relaxation Method (SRM), which uses a phenomenological expression of osmotic stress, are explored to provide the spatio-temporal profiles for polymer density, osmotic stress, and degree of ionization, along with the time evolution of the gel size. Further, we obtain an analytical expression for the elastic modulus for linearized stress in the limit of small deformations. We match our theoretical profiles with the experiments of swelling of PNIPAM (uncharged) and Imidazolium-based (charged) minigels available in the literature. Ministry of Human Resource Development (MHRD), Government of India.

Severe facial swelling in a pregnant woman after using hair dye.

PubMed

van Genderen, Michel E; Carels, Ginette; Lonnee, Edward R; Dees, Adriaan

2014-03-31

A 33-year-old Caucasian pregnant woman (26 weeks' gestation) presented to the emergency department. She had a 2-day history of severe itching of the scalp and steadily worsening swelling of the face over the previous 12 h, which had extended to the neck. She had no difficulty breathing. The itching and swelling had developed 3 days after she had used hair dye. The patient had no history of allergic responses to hair dye or black henna tattoos. A diagnosis of type IV delayed hypersensitivity reaction was made. Permanent hair dyes are the most frequently used professional hair dyes and are most commonly based on paraphenylenediamine (PPD) or related chemicals. PPD is known to be one of the most potent allergens which cause allergic contact dermatitis. After treatment with intravenous antihistamines and steroids, the facial swelling reduced and the patient had completely recovered by the following day.

Coking properties of coal under pressure and their influence on moving-bed gasification. Final report

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

Lancet, M.S.; Curran, G.P.; Sim, F.A.

1982-08-01

The coking properties of seven bituminous coals, including three Eastern US coals, one Midwestern US coal, a Western US coal and two from the UK were studied with respect to the possible utilization of these coals in moving bed gasifier systems. Complete physical, chemical and petrographic analyses were obtained for each coal in addition to the highly specialized CCDC simulated gasifier coking test data. The effects of total pressure, hydrogen partial pressure, heating rate and the addition of gob and tar on the fluidity and swelling properties of each coal was studied. Samples of each coal were shock heated undermore » pressure to simulate coking in the top of a Lurgi gasifier. The resultant cokes were tested for various physical properties and the product yields were determined. Gas release patterns during pressurized pyrolysis were obtained in several instances. The data obtained in this work should provide a valuable data base for future gasifier feedstock evaluation programs.« less

Altering the swelling pressures within in vitro engineered cartilage is predicted to modulate the configuration of the collagen network and hence improve tissue mechanical properties.

PubMed

Nagel, Thomas; Kelly, Daniel J

2013-06-01

Prestress in the collagen network has a significant impact on the material properties of cartilaginous tissues. It is closely related to the recruitment configuration of the collagen network which defines the transition from lax collagen fibres to uncrimped, load-bearing collagen fibres. This recruitment configuration can change in response to alterations in the external environmental conditions. In this study, the influence of changes in external salt concentration or sequential proteoglycan digestion on the configuration of the collagen network of tissue engineered cartilage is investigated using a previously developed computational model. Collagen synthesis and network assembly are assumed to occur in the tissue configuration present during in vitro culture. The model assumes that if this configuration is more compact due to changes in tissue swelling, the collagen network will adapt by lowering its recruitment stretch. When returned to normal physiological conditions, these tissues will then have a higher prestress in the collagen network. Based on these assumptions, the model demonstrates that proteoglycan digestion at discrete time points during culture as well as culture in a hypertonic medium can improve the functionality of tissue engineered cartilage, while culture in hypotonic solution is detrimental to the apparent mechanical properties of the graft. Copyright © 2013 Elsevier Ltd. All rights reserved.

Modeling and simulation of a chemically stimulated hydrogel bilayer bending actuator

NASA Astrophysics Data System (ADS)

Sobczyk, Martin; Wallmersperger, Thomas

2017-04-01

Stimuli-sensitive hydrogels are polymeric materials, which are able to reversibly swell in water in response to evironmental changes. Relevant stimuli include variations of pH, temperature, concentration of specific ions etc. Stacked layers composed of multiple thin hydrogels - also referred to as hydrogel-layer composites - combine the distinct sensing properties of different hydrogels. This approach enables the development of sophisticated microfluidic devices such as bisensitive valves or fluid-sensitive deflectors. In order to numerically simulate the swelling of a polyelectrolyte hydrogel in response to an ion concentration change the multifield theory is adopted. The set of partial differential equations - including the description of the chemical, the electrical and the mechanical field - are solved using the Finite Element Method. Simulations are carried out on a two-dimensional domain in order to capture interactions between the different fields. In the present work, the ion transport is governed by diffusive and migrative fluxes. The distribution of ions in the gel and the solution bath result in an osmotic pressure difference, which is responsible for the mechanical deformation of the hydrogel-layer composite. The realized numerical investigation gives an insight into the evolution of the displacement field, the distribution of ions and the electric potential within the bulk material and the interface between gel and solution bath. The predicted behavior of the relevant field variables is in excellent agreement with results available in the literature.

Experimental determination and modelling of the swelling speed of a hydrogel polymer

NASA Astrophysics Data System (ADS)

Lenk, Sándor; Majoros, Tamás; Beleznai, Szabolcs; Ujhelyi, Ferenc; Péczeli, Imre; Karda, Zsolt; Barócsi, Attila

2018-03-01

When a hydrophilic intraocular lens material is immersed, its volume and mass start increase due to the diffusion of water (or isotonic saline solution) reaching a quasi-equilibrium in a time scale of several hours. Here, we present a combination of atomic force and confocal microscopy to measure the axial swelling speed of such polymers in distilled water. The measurements are used for the experimental verification of a simplistic finite element model developed for engineering applications in COMSOL environment. The model is calibrated with the temporal change of the sample mass. The swelling velocity is found to be inversely proportional to the square root of time.

Pressurized entrained-flow pyrolysis of microalgae: Enhanced production of hydrogen and nitrogen-containing compounds.

PubMed

Maliutina, Kristina; Tahmasebi, Arash; Yu, Jianglong

2018-05-01

Pressurized entrained-flow pyrolysis of Chlorella vulgaris microalgae was investigated. The impact of pressure on the yield and composition of pyrolysis products were studied. The results showed that the concentration of H 2 in bio-gas increased sharply with increasing pyrolysis pressure, while those of CO, CO 2 , CH 4 , and C 2 H 6 were dramatically decreased. The concentration of H 2 reached 88.01 vol% in bio-gas at 900 °C and 4 MPa. Higher pressures promoted the hydrogen transfer to bio-gas. The bio-oils derived from pressurized pyrolysis were rich in nitrogen-containing compounds and PAHs. The highest concentration of nitrogen-containing compounds in bio-oil was achieved at 800 °C and 1 MPa. Increasing pyrolysis pressure promoted the formation of nitrogen-containing compounds such as indole, quinoline, isoquinoline and phenanthridine. Higher pyrolysis pressures led to increased sphericity, enhanced swelling, and higher carbon order of bio-chars. Pressurized pyrolysis of biomass has a great potential for poly-generation of H 2 , nitrogen containing compounds and bio-char. Copyright © 2018 Elsevier Ltd. All rights reserved.

Climatology of Global Swell-Atmosphere Interaction

NASA Astrophysics Data System (ADS)

Semedo, Alvaro

2016-04-01

At the ocean surface wind sea and swell waves coexist. Wind sea waves are locally generated growing waves strongly linked to the overlaying wind field. Waves that propagate away from their generation area, throughout entire ocean basins, are called swell. Swell waves do not receive energy from local wind. Ocean wind waves can be seen as the "gearbox" between the atmosphere and the ocean, and are of critical importance to the coupled atmosphere-ocean system, since they modulate most of the air-sea interaction processes and exchanges, particularly the exchange of momentum. This modulation is most of the times sea-state dependent, i.e., it is a function of the prevalence of one type of waves over the other. The wave age parameter, defined as the relative speed between the peak wave and the wind (c_p⁄U_10), has been largely used in different aspects of the air-sea interaction theory and in practical modeling solutions of wave-atmosphere coupled model systems. The wave age can be used to assess the development of the sea state but also the prevalence (domination) of wind sea or swell waves at the ocean surface. The presence of fast-running waves (swell) during light winds (at high wave age regimes) induces an upward momentum flux, directed from the water surface to the atmosphere. This upward directed momentum has an impact in the lower marine atmospheric boundary layer (MABL): on the one hand it changes the vertical wind speed profile by accelerating the flow at the first few meters (inducing the so called "wave-driven wind"), and on the other hand it changes the overall MABL turbulence structure by limiting the wind shear - in some observed and modeled situations the turbulence is said to have "collapse". The swell interaction with the lower MABL is a function of the wave age but also of the swell steepness, since steeper waves loose more energy into the atmosphere as their energy attenuates. This interaction can be seen as highest in areas where swells are steepest, but also where the wind speed is lowest and consequently the wave age is high. A detailed global climatology of the wave age and swell steepness parameters, based on the ECMWF (European Centre for Medium-Range Weather Forecasts) ERA-Interim reanalysis is presented. It will be shown, in line with previous studies, that the global climatological patterns of the wave age confirm the global dominance of the World Ocean by swell waves. The areas of the ocean where the highest interaction of swell waves and the lower atmosphere can be expected are also presented.

Mechanical analysis of the strains generated by water tension in plant stems. Part I: stress transmission from the water to the cell walls.

PubMed

Alméras, Tancrède; Gril, Joseph

2007-11-01

Plant tissues shrink and swell in response to changes in water pressure. These strains can be easily measured, e.g., at the surface of tree stems, to obtain indirect information about plant water status and other physiological parameters. We developed a mechanical model to clarify how water pressure is transmitted to cell walls and causes shrinkage of plant tissues, particularly in the case of thick-walled cells such as wood fibers. Our analysis shows that the stress inside the fiber cell walls is lower than the water tension. The difference is accounted for by a stress transmission factor that depends on two main effects. The first effect is the dilution of the stress through the cell wall, because water acts at the lumen border and is transmitted to the outer border of the cell, which has a larger circumference. The second effect is the partial conversion of radial stress into tangential stress. Both effects are quantified as functions of parameters of the cell wall structure and its mechanical properties.

Culture of preantral follicles in poly(ethylene) glycol-based, three-dimensional hydrogel: a relationship between swelling ratio and follicular developments

PubMed Central

Ahn, Jong Il; Kim, Gil Ah; Kwon, Hyo Suk; Ahn, Ji Yeon; Hubbell, Jeffrey A; Song, Yong Sang; Lee, Seung Tae; Lim, Jeong Mook

2015-01-01

This study was undertaken to examine how the softness of poly(ethylene) glycol (PEG)-based hydrogels, creating a three-dimensional (3D) microenvironment, influences the in vitro growth of mouse ovarian follicles. Early secondary, preantral follicles of 2 week-old mice were cultured in a crosslinked four-arm PEG hydrogel. The hydrogel swelling ratio, which relates to softness, was modified within the range 25.7–15.5 by increasing the reactive PEG concentration in the precursor solution from 5% to 15% w/v, but it did not influence follicular growth to form the pseudoantrum (60–80%; p = 0.76). Significant (p < 0.04) model effects, however, were detected in the maturation and developmental competence of the follicle-derived oocytes. A swelling ratio of > 21.4 yielded better oocyte maturation than other levels, while the highest competence to develop pronuclear and blastocyst formation was detected at 20.6. In conclusion, gel softness, as reflected in swelling ratio, was one of the essential factors for supporting folliculogenesis in vivo within a hydrogel-based, 3D microenvironment. © 2014 The Authors. Journal of Tissue Engineering and Regenerative Medicine published by John Wiley & Sons, Ltd. PMID:24493269

Conversion of Nitrocellulose to Smokeless Powder

DTIC Science & Technology

1941-01-17

for Various Cellulose Esters. The Correlation of Solvent Power and the Vis- cosity of Cellulose Ester Solutions fi number of binary and ternary...Kon.Akad.WetenSch.Amsterdam The Osmotic Pressure and the Vlscosity3of671ඕ(l933) Nitrocellulose Solutions 6. J.DuClaux and J.Barblere. Bull Soc nbim /k^ ^c...solvents are added to nitrocellulose, swelling oc- curs and if enough solvent is present, the gelatinized mass then passes into a liquid solution

Modeling High-Pressure Gas-Polymer Sorpion Behavior Using the Sanchez-Lacombe Equation of State.

DTIC Science & Technology

1987-06-01

The solubility of a gas in an amorphous or molten polymer is an important consideration in membrane and polymer processes . For instance, the efficacy...to a supercritical fluid during the impregnation process . Swelling the polymer effectively increases the diffusion coefficient of the heavy dopant by...dissolve the impurity, and then diffuse out of the swollen matrix thus removing the impurity. This supercritical fluid extraction process is somewhat

Elastic-Brittle-Plastic Behaviour of Shale Reservoirs and Its Implications on Fracture Permeability Variation: An Analytical Approach

NASA Astrophysics Data System (ADS)

Masoudian, Mohsen S.; Hashemi, Mir Amid; Tasalloti, Ali; Marshall, Alec M.

2018-05-01

Shale gas has recently gained significant attention as one of the most important unconventional gas resources. Shales are fine-grained rocks formed from the compaction of silt- and clay-sized particles and are characterised by their fissured texture and very low permeability. Gas exists in an adsorbed state on the surface of the organic content of the rock and is freely available within the primary and secondary porosity. Geomechanical studies have indicated that, depending on the clay content of the rock, shales can exhibit a brittle failure mechanism. Brittle failure leads to the reduced strength of the plastic zone around a wellbore, which can potentially result in wellbore instability problems. Desorption of gas during production can cause shrinkage of the organic content of the rock. This becomes more important when considering the use of shales for CO2 sequestration purposes, where CO2 adsorption-induced swelling can play an important role. These phenomena lead to changes in the stress state within the rock mass, which then influence the permeability of the reservoir. Thus, rigorous simulation of material failure within coupled hydro-mechanical analyses is needed to achieve a more systematic and accurate representation of the wellbore. Despite numerous modelling efforts related to permeability, an adequate representation of the geomechanical behaviour of shale and its impact on permeability and gas production has not been achieved. In order to achieve this aim, novel coupled poro-elastoplastic analytical solutions are developed in this paper which take into account the sorption-induced swelling and the brittle failure mechanism. These models employ linear elasticity and a Mohr-Coulomb failure criterion in a plane-strain condition with boundary conditions corresponding to both open-hole and cased-hole completions. The post-failure brittle behaviour of the rock is defined using residual strength parameters and a non-associated flow rule. Swelling and shrinkage are considered to be elastic and are defined using a Langmuir-like curve, which is directly related to the reservoir pressure. The models are used to evaluate the stress distribution and the induced change in permeability within a reservoir. Results show that development of a plastic zone near the wellbore can significantly impact fracture permeability and gas production. The capabilities and limitations of the models are discussed and potential future developments related to modelling of permeability in brittle shales under elastoplastic deformations are identified.

Progression of asymptomatic optic disc swelling to non-arteritic anterior ischaemic optic neuropathy.

PubMed

Subramanian, Prem S; Gordon, Lynn K; Bonelli, Laura; Arnold, Anthony C

2017-05-01

The time of onset of optic disc swelling in non-arteritic anterior ischaemic optic neuropathy (NAION) is not known, and it is commonly assumed to arise simultaneously with vision loss. Our goal is to report the presence and persistence of optic disc swelling without initial vision loss and its subsequent evolution to typical, symptomatic NAION. Clinical case series of patients with optic disc swelling and normal visual acuity and visual fields at initial presentation who progressed to have vision loss typical of NAION. All subjects underwent automated perimetry, disc photography and optic coherence tomography and/or fluorescein angiography to evaluate optic nerve function and perfusion. Four patients were found to have sectoral or diffuse optic disc swelling without visual acuity or visual field loss; the fellow eye of all four had either current or prior NAION or a 'disc at risk' configuration. Over several weeks of clinical surveillance, each patient experienced sudden onset of visual field and/or visual acuity loss typical for NAION. Current treatment options for NAION once vision loss occurs are limited and may not alter the natural history of the disorder. Subjects with NAION may have disc swelling for 2-10 weeks prior to the occurrence of visual loss, and with the development of new therapeutic agents, treatment at the time of observed disc swelling could prevent vision loss from NAION. 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/.

In vivo optophysiology reveals that G-protein activation triggers osmotic swelling and increased light scattering of rod photoreceptors

PubMed Central

Nguyen, Phuong T.; Yarov-Yarovoy, Vladimir; Burns, Marie E.; Pugh, Edward N.

2017-01-01

The light responses of rod and cone photoreceptors have been studied electrophysiologically for decades, largely with ex vivo approaches that disrupt the photoreceptors’ subretinal microenvironment. Here we report the use of optical coherence tomography (OCT) to measure light-driven signals of rod photoreceptors in vivo. Visible light stimulation over a 200-fold intensity range caused correlated rod outer segment (OS) elongation and increased light scattering in wild-type mice, but not in mice lacking the rod G-protein alpha subunit, transducin (Gαt), revealing these responses to be triggered by phototransduction. For stimuli that photoactivated one rhodopsin per Gαt the rod OS swelling response reached a saturated elongation of 10.0 ± 2.1%, at a maximum rate of 0.11% s−1. Analyzing swelling as osmotically driven water influx, we find the H2O membrane permeability of the rod OS to be (2.6 ± 0.4) × 10−5 cm⋅s−1, comparable to that of other cells lacking aquaporin expression. Application of Van’t Hoff’s law reveals that complete activation of phototransduction generates a potentially harmful 20% increase in OS osmotic pressure. The increased backscattering from the base of the OS is explained by a model combining cytoplasmic swelling, translocation of dissociated G-protein subunits from the disc membranes into the cytoplasm, and a relatively higher H2O permeability of nascent discs in the basal rod OS. Translocation of phototransduction components out of the OS may protect rods from osmotic stress, which could be especially harmful in disease conditions that affect rod OS structural integrity. PMID:28320964

Effect of defect imbalance on void swelling distributions produced in pure iron irradiated with 3.5 MeV self-ions

DOE PAGES

Shao, Lin; Wei, C. -C.; Gigax, J.; ...

2014-06-10

Ion irradiation has been widely used to simulate radiation damage induced by neutrons. However, there are a number of features of ion-induced damage that differ from neutron-induced damage, and these differences require investigation before behavior arising from neutron bombardment can be confidently predicted from ion data. In this study 3.5 MeV self-ion irradiation of pure iron was used to study the influence on void swelling of the depth-dependent defect imbalance between vacancies and interstitials that arises from various surface effects, forward scattering of displaced atoms, and especially the injected interstitial effect. The depth dependence of void swelling was observed notmore » to follow the behavior anticipated from the depth dependence of the damage rate. Void nucleation and growth develop first in the lower-dose, near-surface region, and then, during continued irradiation, move to progressively deeper and higher-damage depths. This indicates a strong initial suppression of void nucleation in the peak damage region that continued irradiation eventually overcomes. This phenomenon is shown by the Boltzmann transport equation method to be due to depth-dependent defect imbalances created under ion irradiation. These findings thus demonstrate that void swelling does not depend solely on the local dose level and that this sensitivity of swelling to depth must be considered in extracting and interpreting ion-induced swelling data.« less

Sorption Behavior of Compressed CO2 and CH4 on Ultrathin Hybrid Poly(POSS-imide) Layers.

PubMed

Raaijmakers, Michiel J T; Ogieglo, Wojciech; Wiese, Martin; Wessling, Matthias; Nijmeijer, Arian; Benes, Nieck E

2015-12-09

Sorption of compressed gases into thin polymeric films is essential for applications including gas sensors and membrane based gas separation. For glassy polymers, the sorption behavior is dependent on the nonequilibrium status of the polymer. The uptake of molecules by a polymer is generally accompanied by dilation, or swelling, of the polymer material. In turn, this dilation can result in penetrant induced plasticization and physical aging that affect the nonequilibrium status of the polymer. Here, we investigate the dilation and sorption behavior of ultrathin membrane layers of a hybrid inorganic-organic network material that consists of alternating polyhedral oligomeric silsesquioxane and imide groups, upon exposure to compressed carbon dioxide and methane. The imide precursor contains fluoroalkene groups that provide affinity toward carbon dioxide, while the octa-functionalized silsesquioxane provides a high degree of cross-linking. This combination allows for extremely high sorption capacities, while structural rearrangements of the network are hindered. We study the simultaneous uptake of gases and dilation of the thin films at high pressures using spectroscopic ellipsometry measurements. Ellipsometry provides the changes in both the refractive index and the film thickness, and allows for accurate quantification of sorption and swelling. In contrast, gravimetric and volumetric measurements only provide a single parameter; this does not allow an accurate correction for, for instance, the changes in buoyancy because of the extensive geometrical changes of highly swelling films. The sorption behavior of the ultrathin hybrid layers depends on the fluoroalkene group content. At low pressure, the apparent molar volume of the gases is low compared to the liquid molar volume of carbon dioxide and methane, respectively. At high gas concentrations in the polymer film, the apparent molar volume of carbon dioxide and methane exceeds that of the liquid molar volume, and approaches that of the gas phase. The high sorption capacity and reversible dilation characteristics of the presented materials provide new directions for applications including gas sensors and gas separation membranes.

Embryonic development of Carabus insulicola (Insecta, Coleoptera, Carabidae) with special reference to external morphology and tangible evidence for the subcoxal theory.

PubMed

Kobayashi, Yukimasa; Niikura, Kazuhiro; Oosawa, Yuuki; Takami, Yasuoki

2013-12-01

The egg morphology and successive changes in the developing embryos of the carabid ground beetle Carabus insulicola (Carabidae) are described based on light and scanning electron microscopy observations. Newly laid eggs of this species are ellipsoid and measure approximately 6.1 × 2.9 mm, before increasing to 6.6 × 3.4 mm at hatching. The egg period is about 11 days at 23°C. The egg shell is characterized by a thin fragile chorion covering a hard serosal cuticle. The embryo forms on the ventral egg surface, where it develops for the duration of the egg period. During the process of thoracic leg formation, two subcoxal rings, subcoxae-1 and 2, are clearly discernible at the basalmost region of the leg rudiments, and these subcoxae participate in the formation of the larval pleura and sterna. The result thus provides tangible evidence for the subcoxal theory, that is, that thoracic pleura and sterna are derived from subcoxal regions. Despite the complete absence of abdominal appendages in the larvae of this species, two pairs of appendage-like swellings, the medial and lateral ones, temporarily arise in the first eight abdominal segments during the middle of embryonic development. The medial swellings are assumed to be serially homologous with the coxal part of the thoracic leg, and they later flatten out and participate in the formation of the larval pleura (hypopleurites). In the light of the serially homologous relationships among gnathal appendages, thoracic legs, and abdominal appendage-like swellings, we identified the subcoxal regions in both the gnathal and abdominal segments. Although, the lateral swellings soon degenerate and disappear, it is considered that the swellings originate in the abdominal subcoxae-2 and may be homologous to the tracheal gills of larvae of Gyrinidae. Based on the embryological results, new interpretations for the constituent of gnathal appendages are proposed. Copyright © 2013 Wiley Periodicals, Inc.

Brain damage in fatal non-missile head injury without high intracranial pressure.

PubMed Central

Graham, D I; Lawrence, A E; Adams, J H; Doyle, D; McLellan, D R

1988-01-01

As part of a comprehensive study of brain damage in 635 fatal non-missile head injuries, the type and prevalence of brain damage occurring in the absence of high intracranial pressure were analysed. Of 71 such cases, 53 sustained their injury as a result of a road traffic accident; only 25 experienced a lucid interval. Thirty eight had a fractured skull, a mean total contusion index of 12.9 and diffuse axonal injury in 29: severe to moderate ischaemic damage was present in the cerebral cortex in 25, brain swelling in 13, and acute bacterial meningitis in nine. The prevalence and range of brain damage that may occur in the absence of high intracranial pressure are important to forensic pathologists in the medicolegal interpretation of cases of fatal head injury. PMID:3343378

Multicycle Wilhelmy plate method for wetting properties, swelling and liquid sorption of wood.

PubMed

Moghaddam, Maziar Sedighi; Wålinder, Magnus E P; Claesson, Per M; Swerin, Agne

2013-10-01

A multicycle Wilhelmy plate method has been developed to investigate wetting properties, liquid sorption, and swelling of porous substrates such as wood. The use of the method is exemplified by studies of wood veneers of Scots pine sapwood and heartwood, which were subjected to repeated immersion and withdrawal in a swelling liquid (water) and in a nonswelling liquid (octane). The swelling liquid changes the sample dimensions during measurements, in particular its perimeter. This, in turn, influences the force registered. A model based on a linear combination of the measured force and final change in sample perimeter is suggested, and validated to elucidate the dynamic perimeter change of wood veneer samples. We show that pine heartwood and pine sapwood differ in several respects in their interaction with water. Pine heartwood showed (i) lower liquid uptake, (ii) lower swelling, (iii) higher contact angle, and (iv) lower level of dissolution of surface active components (extractives) than pine sapwood. We conclude that the method is also suitable for studying wetting properties of other porous and swellable materials. The wettability results were supported by surface chemical analysis using X-ray photoelectron spectroscopy, showing higher extractives and lignin content on heartwood than on sapwood surfaces.

Reversible Structural Swell-Shrink and Recoverable Optical Properties in Hybrid Inorganic-Organic Perovskite.

PubMed

Zhang, Yupeng; Wang, Yusheng; Xu, Zai-Quan; Liu, Jingying; Song, Jingchao; Xue, Yunzhou; Wang, Ziyu; Zheng, Jialu; Jiang, Liangcong; Zheng, Changxi; Huang, Fuzhi; Sun, Baoquan; Cheng, Yi-Bing; Bao, Qiaoliang

2016-07-26

Ion migration in hybrid organic-inorganic perovskites has been suggested to be an important factor for many unusual behaviors in perovskite-based optoelectronics, such as current-voltage hysteresis, low-frequency giant dielectric response, and the switchable photovoltaic effect. However, the role played by ion migration in the photoelectric conversion process of perovskites is still unclear. In this work, we provide microscale insights into the influence of ion migration on the microstructure, stability, and light-matter interaction in perovskite micro/nanowires by using spatially resolved optical characterization techniques. We observed that ion migration, especially the migration of MA(+) ions, will induce a reversible structural swell-shrink in perovskites and recoverably affect the reflective index, quantum efficiency, light-harvesting, and photoelectric properties. The maximum ion migration quantity in perovskites was as high as approximately 30%, resulting in lattice swell or shrink of approximately 4.4%. Meanwhile, the evidence shows that ion migration in perovskites could gradually accelerate the aging of perovskites because of lattice distortion in the reversible structural swell-shrink process. Knowledge regarding reversible structural swell-shrink and recoverable optical properties may shed light on the development of optoelectronic and converse piezoelectric devices based on perovskites.

Structural elucidation, molecular representation and solvent interactions of vitrinite-rich and inertinite-rich South African coals

NASA Astrophysics Data System (ADS)

van Niekerk, Daniel

The structural differences and similarities of two Permian-aged South African coals, vitrinite-rich Waterberg and inertinite-rich Highveld coals (similar rank, carbon content and Permian age), were evaluated. With South African coals the opportunity presented itself to study not only Permian-aged Gondwana vitrinite but also inertinite. It was expected that these coals would differ from Northern hemisphere Carboniferous coals. It was concluded from various structural data that both coals, although different in maceral composition and depositional basins, are similar in their base structural composition. The main differences were that the inertinite-rich Highveld coal was more ordered, more aromatic, and had less hydrogen than the vitrinite-rich Waterberg coal. Analytical data were used to construct large-scale advanced molecular representations for vitrinite-rich Waterberg and inertinite-rich Highveld coals. The three-dimensional models were structurally diverse with a molecular weight range of 78 to 1900 amu. The vitrinite-rich coal model consisted of 18,572 atoms and 191 individual molecules and the inertinite-rich coal model consisted of 14,242 atoms and 158 individual molecules. This largescale modeling effort was enabled by the development of various PERL scripts to automate various visualization and analytical aspects. Coal swelling studies were conducted using the traditional pack-bed swelling method and a new novel single-particle stop-motion videography swelling method with NMP and CS2/NMP solvents. The pack-bed swelling showed that vitrinite-rich coal had a greater swelling extent and that swelling extent for both coals was greater in CS2/NMP binary solvent than for NMP. Single-particle swelling experiments showed that both coals, for both solvents, exhibit overshoot-type and climbing-type swelling behaviors. Inertinite-coal had a faster swelling rate, in both solvents, than the vitrinite-rich coal. The single-particle swelling data was used to calculate the kinetic parameters and it was found that the swelling was governed by relaxation of the coal structure (super-Case II swelling). X-ray computed tomography was conducted confirming anisotropic swelling. The petrographic transitions (maceral-group composition and reflectance) with solvent swelling and extraction were quantified. No changes in the maceral compositions were found, but changes in some coal particles were observed. Random reflectance analysis showed that, for both vitrinite and inertinite, there is a decrease in reflectance values with solvent treatment. Vitrinite reflectograms showed a shift from the dominant reflecting V-types to lower V-types. The inertinite reflectograms exhibited an increase in number of I-types (broadening of reflectrograms). Molecular simulation and visualization approaches to solvent swelling and extraction were performed on the proposed molecular models of vitrinite-rich and inertinite-rich coals. A theoretical extraction yield was determined using solubility parameters and showed agreement with experimental extraction yield trends. Statistical Associating Fluid Theory (SAFT) modeling was explored to test whether this method could predict swelling extent. The predicted swelling trends of SAFT were comparable to that of the experimental swelling results. SAFT was found to be a promising tool for solvent-coal interaction predictions. Partially solvent swollen structures were constructed by the addition of solvent molecules to the original coal molecules using a amorphous building approach. This method showed that coal-coal non-bonding interaction changed with the introduction of solvent. A disruption in the van der Waals interaction energies and a change in hydrogen bond distributions were observed in the swollen coal models and quantified. It was concluded that small changes in coal structure translates to significant changes in solvent interaction behavior. These changes were successfully visualized and simulated using atomistic molecular representations.

Stress Singularities in Swelling Soft Solids.

PubMed

Goriely, Alain; Weickenmeier, Johannes; Kuhl, Ellen

2016-09-23

When a swelling soft solid is rigidly constrained on all sides except for a circular opening, it will bulge out to expand as observed during decompressive craniectomy, a surgical procedure used to reduce stresses in swollen brains. While the elastic energy of the solid decreases throughout this process, large stresses develop close to the opening. At the point of contact, the stresses exhibit a singularity similar to the ones found in the classic punch indentation problem. Here, we study the stresses generated by swelling and the evolution of the bulging shape associated with this process. We also consider the possibility of damage triggered by zones of either high shear stresses or high fiber stretches.

Beam-contamination-induced compositional alteration and its neutron-atypical consequences in ion simulation of neutron-induced void swelling

DOE PAGES

Gigax, Jonathan G.; Kim, Hyosim; Aydogan, Eda; ...

2017-05-16

Although accelerator-based ion irradiation has been widely accepted to simulate neutron damage, neutron-atypical features need to be carefully investigated. In this study, we have shown that Coulomb force drag by ion beams can introduce significant amounts of carbon, nitrogen, and oxygen into target materials even under ultra-high vacuum conditions. The resulting compositional and microstructural changes dramatically suppress void swelling. By applying a beam-filtering technique, introduction of vacuum contaminants is greatly minimized and the true swelling resistance of the alloys is revealed and matches neutron behavior closely. These findings are a significant step toward developing standardized procedures for emulating neutron damage.

Drainage and Landscape Evolution in the Bighorn Basin Accompanying Advection of the Yellowstone Hotspot Swell Through North America

NASA Astrophysics Data System (ADS)

Guerrero, E. F.; Meigs, A.

2012-12-01

Mantle plumes have been recognized to express themselves on the surface as long wavelength and low amplitude topographic swells. These swells are measured as positive geoid anomalies and include shorter wavelength topographic features such as volcanic edifices and pre-exisitng topography. Advection of the topographic swell is expected as the lithosphere passes over the plume uplift source. The hot spot swell occurs in the landscape as transient signal that is expressed with waxing and waning topography. Waxing topography occurs at the leading edge of the swell and is expressed as an increase in rock uplift that is preserved by rivers and landscapes. Advection of topography predicts a shift in a basin from deposition to incision, an increase in convexity of a transverse river's long profile and a lateral river migration in the direction of advection. The Yellowstone region has a strong positive geoid anomaly and the volcanic signal, which have been interpreted as the longer and shorter wavelength topographic expressions of the hot spot. These expressions of the hot spot developed in a part of North America with a compounded deformation and topographic history. Previous studies of the Yellowstone topographic swell have concentrated on the waning or trailing signal preserved in the Snake River Plain. Our project revisits the classic geomorphology study area in the Bighorn Basin of Wyoming and Montana, which is in leading edge of the swell. Present models identify the swell as having a 400 km in diameter and that it is centered on the Yellowstone caldera. If we assume advection to occur in concert with the caldera eruptive track, the Yellowstone swell has migrated to the northeast at a rate of 3 cm yr-1 and began acting on the Bighorn Basin's landscape between 3 and 2 Ma. The Bighorn Basin has an established history of a basin-wide switch from deposition to incision during the late Pliocene, yet the age control on the erosional evolution of the region is relative. This basin is an ideal location to quantify long wavelength dynamic topography due to its low relief. Long river profiles streams that are transverse to the topographic swell in the basin suggest a transient advective signal preserved as profile knickpoints. Abandoned strath terraces, stream piracy, drainage reorganization, and lateral channel migration within the Bighorn Basin are all consistent indicators of the advection of a topographic swell. However, the lack of a high-resolution absolute age chronology precludes us from attributing the primary landscape and drainage forcing to climate change or dynamic topography. Our future work will focus on the timing of geomorphic and river profile evolution to disentangle competing effects of topographic advection, climate, and other factors.

Gingival abscess due to an unusual nail-biting habit: a case report.

PubMed

Sousa, Denise; Pinto, Daniela; Araujo, Rebecca; Rego, Rodrigo Otavio; Moreira-Neto, Jose

2010-03-01

Nail-biting is one of the most frequent deleterious oral habits in children. It can result in systemic diseases or oral traumatic lesion. This report describes a case of gingival abscess in a child due to a fingernail-biting habit. A 5-year, 6-month-old female presented gingival swelling and fistula in the primary maxillary left central and right lateral incisors as an unusual sequelae to the periodontal tissues from fingernail-biting. A periodontal curette was used to remove the fragments and to curette the area. After the curettage, an exudate of blood and pus was drained. Then the area was irrigated with 0.12% chlorhexidine solution; applying finger pressure controlled the secretion. After one week, the patient returned with gingival swelling present in the same teeth. The same curettage procedure was performed. It was suggested that the deleterious habit was related to emotional tension and anxiety behaviors and the patient was referred for psychological treatment. When the patient returned one month later, she was still biting her fingernails, but she had stopped placing fragments into the gingival crevice. No more gingival inflammation or swelling was observed. his paper presents an unusual case report of a gingival abscess due to a fingernail-biting habit in a child, probably related to an emotional condition. The fingernail-biting habit can induce a periodontal traumatic injury yielding a more serious complication such as a gingival abscess.

Wind and wave dataset for Matara, Sri Lanka

NASA Astrophysics Data System (ADS)

Luo, Yao; Wang, Dongxiao; Priyadarshana Gamage, Tilak; Zhou, Fenghua; Madusanka Widanage, Charith; Liu, Taiwei

2018-01-01

We present a continuous in situ hydro-meteorology observational dataset from a set of instruments first deployed in December 2012 in the south of Sri Lanka, facing toward the north Indian Ocean. In these waters, simultaneous records of wind and wave data are sparse due to difficulties in deploying measurement instruments, although the area hosts one of the busiest shipping lanes in the world. This study describes the survey, deployment, and measurements of wind and waves, with the aim of offering future users of the dataset the most comprehensive and as much information as possible. This dataset advances our understanding of the nearshore hydrodynamic processes and wave climate, including sea waves and swells, in the north Indian Ocean. Moreover, it is a valuable resource for ocean model parameterization and validation. The archived dataset (Table 1) is examined in detail, including wave data at two locations with water depths of 20 and 10 m comprising synchronous time series of wind, ocean astronomical tide, air pressure, etc. In addition, we use these wave observations to evaluate the ERA-Interim reanalysis product. Based on Buoy 2 data, the swells are the main component of waves year-round, although monsoons can markedly alter the proportion between swell and wind sea. The dataset (Luo et al., 2017) is publicly available from Science Data Bank (https://doi.org/10.11922/sciencedb.447).

Confined wetting of FoCa clay powder/pellet mixtures: Experimentation and numerical modeling

NASA Astrophysics Data System (ADS)

Maugis, Pascal; Imbert, Christophe

Potential geological nuclear waste disposals must be properly sealed to prevent contamination of the biosphere by radionuclides. In the framework of the RESEAL project, the performance of a bentonite shaft seal is currently studied at Mol (Belgium). This paper focuses on the hydro-mechanical physical behavior of centimetric, unsaturated samples of the backfilling material - a mixture of FoCa-clay powder and pellets - during oedometer tests. The hydro-mechanical response of the samples is observed experimentally, and then compared to numerical simulations performed by our Cast3M Finite Element code. The generalized Darcy’s law and the Barcelona Basic Model mechanical model formed the physical basis of the numerical model and the interpretation. They are widely used in engineered barriers modeling. Vertical swelling pressure and water intake were measured throughout the test. Although water income presents a monotonous increase, the swelling pressure evolution is marked by a peak, and then a local minimum before increasing again to an asymptotic value. This unexpected behavior is explained by yielding rather than by heterogeneity. It is satisfactorily reproduced by the model after parameter calibration. Several samples with different heights ranging from 5 to 12 cm show the same hydro-mechanical response, apart from a dilatation of the time scale. The interest of the characterization of centimetric samples to predicting the efficiency of a metric sealing is discussed.

[Vacuum sealing drainage for infection wound in earthquake].

PubMed

Liao, Dengbin; Ning, Ning; Liu, Xiaoyan; Gan, Chunlan

2009-10-01

To investigate the effect of vacuum sealing drainage (VSD) technology on prevention and treatment of infection wound and to repair the infectious fracture wound in earthquake. Twenty-two patients with limb fractures and open infection wound received VSD from May 12, 2008 to June 19, 2008 in West China Hospital of Sichuan University. Before the VSD, we debrided all wounds and gave effective systemic antibiotics. A -18 ~ -14 kPa pressure was exerted to the wound, and the VSD was used for 8-10 days. We took a germiculture regularly. The capacity, color, and nature of negative pressure drainage, the regression of limb swelling, and systemic inflammatory responses were observed. There was no active bleeding wound or transparent film off in all patients. Three patients had drainage clogging, and were kept flowing freely using the sterile saline pipe to remove the blockage of necrotic tissues. During the VSD, granulation tissues grew well in the 13 patients with bone exposure of the wounded. Two patients whose symptom of inflammatory was not obviously eased had another debridement to completely remove the necrosis, and the symptom was relieved. After 3-5 days of VSD, swelling and fever in the other 20 patients significantly subsided. VSD can alleviate the wound inflammation, facilitate the growth of the fresh granulation tissue from the surrounding to the center, and reduce the flap transfer area for the Stage II coverage of the exposed bone.

The mechanism of muscle injury in the crush syndrome: ischemic versus pressure-stretch myopathy.

PubMed

Better, O S; Abassi, Z; Rubinstein, I; Marom, S; Winaver, Y; Silberman, M

1990-01-01

Crush injuries are ubiquitous, common sequelae in victims of seismic, industrial and military catastrophes, and were considered to be mainly due to ischemia of the affected limbs. Our clinical experience suggests that early in the crush syndrome, interference with the circulation may occur but is rare. The predominant earliest lesion in the crush syndrome is postulated to be pressure-stretch myopathy, rather than ischemic myopathy. It is proposed that at the membrane level, stretch increases sarcoplasmic influx of Na, Cl, H2O and Ca down their electrochemical gradient. Energy-requiring cationic extrusion pumps work at maximal capacity, but are unable to cope with the increased load. This results in cell swelling and increase in cytosolic and mitochondrial calcium with activation of autolytic destructive processes and interference with cellular respiration. Extensive muscle swelling may cause late muscle tamponade and myoneural ischemic damage (compartmental syndrome). Thus, whereas prevalent theory suggests that the sarcolemmal cationic pump activity is attenuated in the crush syndrome due to early ischemia, we propose that the cationic extrusion pump is maximally activated as in the amphotericin B model. Because the cationic pump is maximally activated in the stretched muscle and in cells exposed to amphotericin, these models rapidly deplete their scarce ATP stores and are susceptible to hypoxia in the face of initially normal circulation.

Scaling Theory of Polyelectrolyte Nanogels

NASA Astrophysics Data System (ADS)

Qu, Li-Jian

2017-08-01

The present paper develops the scaling theory of polyelectrolyte nanogels in dilute and semidilute solutions. The dependencies of the nanogel dimension on branching topology, charge fraction, subchain length, segment number, solution concentration are obtained. For a single polyelectrolyte nanogel in salt free solution, the nanogel may be swelled by the Coulombic repulsion (the so-called polyelectrolyte regime) or the osmotic counterion pressure (the so-called osmotic regime). Characteristics and boundaries between different regimes of a single polyelectrolyte nanogel are summarized. In dilute solution, the nanogels in polyelectrolyte regime will distribute orderly with the increase of concentration. While the nanogels in osmotic regime will always distribute randomly. Different concentration dependencies of the size of a nanogel in polyelectrolyte regime and in osmotic regime are also explored. Supported by China Earthquake Administration under Grant No. 20150112 and National Natural Science Foundation of China under Grant No. 21504014

SwellGel: an affinity chromatography technology for high-capacity and high-throughput purification of recombinant-tagged proteins.

PubMed

Draveling, C; Ren, L; Haney, P; Zeisse, D; Qoronfleh, M W

2001-07-01

The revolution in genomics and proteomics is having a profound impact on drug discovery. Today's protein scientist demands a faster, easier, more reliable way to purify proteins. A high capacity, high-throughput new technology has been developed in Perbio Sciences for affinity protein purification. This technology utilizes selected chromatography media that are dehydrated to form uniform aggregates. The SwellGel aggregates will instantly rehydrate upon addition of the protein sample, allowing purification and direct performance of multiple assays in a variety of formats. SwellGel technology has greater stability and is easier to handle than standard wet chromatography resins. The microplate format of this technology provides high-capacity, high-throughput features, recovering milligram quantities of protein suitable for high-throughput screening or biophysical/structural studies. Data will be presented applying SwellGel technology to recombinant 6x His-tagged protein and glutathione-S-transferase (GST) fusion protein purification. Copyright 2001 Academic Press.

Chemical crosslinking of acrylic acid to form biocompatible pH sensitive hydrogel reinforced with cellulose nanocrystals (CNC)

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

Lim, Lim Sze; Ahmad, Ishak; Lazim, Mohd Azwani Shah Mat

2014-09-03

The purpose of this study is to produce a novel pH and temperature sensitive hydrogel, composed of poly(acrylic acid) (PAA) and cellulose nanocrystal (CNC). CNC was extracted from kenaf fiber through a series of alkali and bleaching treatments followed by acid hydrolysis. The PAA was then subjected to chemical cross-linking using the cross-linking agent (N,N-methylenebisacrylamide) with CNC entrapped in PAA matrix. The mixture was casted onto petri dish to obtain disc shape hydrogel. The effects of reaction conditions such as the ratio of PAA and CNC on the swelling behavior of the hydrogel obtained towards pH and temperature were studied.more » The obtained hydrogel was further subjected to different tests such swelling test for swelling behaviour at different pH and temperature along with scanning electron microscopy (SEM) for morphology analysis. The hydrogel obtained showed excellent pH sensitivity and obtained maximum swelling at pH 7. Besides that, hydrogel obtained showed significant increase in swelling ratio when temperature of swelling medium was increased from 25°C to 37°C. SEM micrograph showed that the pore size of the hydrogel decreases with increase of CNC content proving that the hydrogel structure became more rigid with addition of CNC. The PAA/CNC hydrogel with such excellent sensitivity towards pH and temperature can be developed further as drug carrier.« less

Comparison of high-pressure CO 2 sorption isotherms on Eastern and Western US coals

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

Romanov, V; Hur, T -B; Fazio, J

2013-10-01

Accurate estimation of carbon dioxide (CO 2) sorption capacity of coal is important for planning the CO 2 sequestration efforts. In this work, we investigated sorption and swelling behavior of several Eastern and Western US coal samples from the Central Appalachian Basin and from San Juan Basin. The CO 2 sorption isotherms have been completed at 55°C for as received and dried samples. The role of mineral components in coal, the coal swelling, the effects of temperature and moisture, and the error propagation have been analyzed. Changes in void volume due to dewatering and other factors such as temporary cagingmore » of carbon dioxide molecules in coal matrix were identified among the main factors affecting accuracy of the carbon dioxide sorption isotherms. The (helium) void volume in the sample cells was measured before and after the sorption isotherm experiments and was used to build the volume-corrected data plots.« less

Hypothyroid-induced acute compartment syndrome in all extremities.

PubMed

Musielak, Matthew C; Chae, Jung Hee

2016-12-20

Acute compartment syndrome (ACS) is an uncommon complication of uncontrolled hypothyroidism. If unrecognized, this can lead to ischemia, necrosis and potential limb loss. A 49-year-old female presented with the sudden onset of bilateral lower and upper extremity swelling and pain. The lower extremity anterior compartments were painful and tense. The extensor surface of the upper extremities exhibited swelling and pain. Motor function was intact, however, limited due to pain. Bilateral lower extremity fasciotomies were performed. Postoperative Day 1, upper extremity motor function decreased significantly and paresthesias occurred. She therefore underwent bilateral forearm fasciotomies. The pathogenesis of hypothyroidism-induced compartment syndrome is unclear. Thyroid-stimulating hormone-induced fibroblast activation results in increased glycosaminoglycan deposition. The primary glycosaminoglycan in hypothyroid myxedematous changes is hyaluronic acid, which binds water causing edema. This increases vascular permeability, extravasation of proteins and impaired lymphatic drainage. These contribute to increased intra-compartmental pressure and subsequent ACS. Published by Oxford University Press and JSCR Publishing Ltd. All rights reserved. © The Author 2016.

Mechanistic modelling of drug release from polymer-coated and swelling and dissolving polymer matrix systems.

PubMed

Kaunisto, Erik; Marucci, Mariagrazia; Borgquist, Per; Axelsson, Anders

2011-10-10

The time required for the design of a new delivery device can be sensibly reduced if the release mechanism is understood and an appropriate mathematical model is used to characterize the system. Once all the model parameters are obtained, in silico experiments can be performed, to provide estimates of the release from devices with different geometries and compositions. In this review coated and matrix systems are considered. For coated formulations, models describing the diffusional drug release, the osmotic pumping drug release, and the lag phase of pellets undergoing cracking in the coating due to the build-up of a hydrostatic pressure are reviewed. For matrix systems, models describing pure polymer dissolution, diffusion in the polymer and drug release from swelling and eroding polymer matrix formulations are reviewed. Importantly, the experiments used to characterize the processes occurring during the release and to validate the models are presented and discussed. Copyright © 2011 Elsevier B.V. All rights reserved.

Methods of making membrane electrode assemblies

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

Kim, Yu Seung; Lee, Kwan -Soo; Rockward, Tommy Q. T.

Method of making a membrane electrode assembly comprising: providing a membrane comprising a perfluorinated sulfonic acid; providing a first transfer substrate; applying to a surface of the first transfer substrate a first ink, said first ink comprising an ionomer and a catalyst; applying to the first ink a suitable non-aqueous swelling agent; forming an assembly comprising: the membrane; and the first transfer substrate, wherein the surface of the first transfer substrate comprising the first ink and the non-aqueous swelling agent is disposed upon one surface of the membrane; and heating the assembly at a temperature of 150.degree. C. or lessmore » and at a pressure of from about 250 kPa to about 3000 kPa or less for a time suitable to allow substantially complete transfer of the first ink and the second ink to the membrane; and cooling the assembly to room temperature and removing the first transfer substrate and the second transfer substrate.« less

Bilateral Parotid Swelling in Polycystic Ovarian Syndrome.

PubMed

Yakubov, Yakov; Mandel, Louis

2016-05-01

Polycystic ovarian syndrome (PCOS) is recognized by the presence of polycystic ovaries, irregular menstruation, and increased androgen levels. Many patients have insulin resistance or impaired glucose tolerance and an associated development of type 2 diabetes mellitus. A patient with PCOS is presented whose cosmetic concerns centered on the prolonged existence of substantial bilateral parotid swelling. The pathophysiology, diagnosis, and therapy of sialosis are discussed. Copyright © 2016. Published by Elsevier Inc.

Quantitative evaluation of polymer concentration profile during swelling of hydrophilic matrix tablets using 1H NMR and MRI methods.

PubMed

Baumgartner, Sasa; Lahajnar, Gojmir; Sepe, Ana; Kristl, Julijana

2005-02-01

Many pharmaceutical tablets are based on hydrophilic polymers, which, after exposure to water, form a gel layer around the tablet that limits the dissolution and diffusion of the drug and provides a mechanism for controlled drug release. Our aim was to determine the thickness of the swollen gel layer of matrix tablets and to develop a method for calculating the polymer concentration profile across the gel layer. MR imaging has been used to investigate the in situ swelling behaviour of cellulose ether matrix tablets and NMR spectroscopy experiments were performed on homogeneous hydrogels with known polymer concentration. The MRI results show that the thickest gel layer was observed for hydroxyethylcellulose tablets, followed by definitely thinner but almost equal gel layer for hydroxypropylcellulose and hydroxypropylmethylcellulose of both molecular weights. The water proton NMR relaxation parameters were combined with the MRI data to obtain a quantitative description of the swelling process on the basis of the concentrations and mobilities of water and polymer as functions of time and distance. The different concentration profiles observed after the same swelling time are the consequence of the different polymer characteristics. The procedure developed here could be used as a general method for calculating polymer concentration profiles on other similar polymeric systems.

Superporous thermo-responsive hydrogels by combination of cellulose fibers and aligned micropores.

PubMed

Halake, Kantappa S; Lee, Jonghwi

2014-05-25

In the area of artificial hydrogels, simultaneous engineering of the volume transition characteristics and mechanical properties of stimuli-responsive hydrogels is an important subject. By unrestricted architecting of hierarchical structures, natural hydrogels are able to provide a wide range of swelling and mechanical properties, beyond the limits of artificial hydrogels. Herein, a combination of nanostructures and microstructures was developed to construct superporous hydrogels. Fibers of microfibrillated cellulose (MFC), an eco-friendly reinforcing material, were used as nanostructures, aligned micropores were used as microstructures, and in situ photopolymerization was used to immobilize the two structures together within the gel networks of poly(N-isopropyl acrylamide) (PNIPAm). The introduction of MFC distinctly enhanced volume transition, mainly by decreasing the swelling ratios above the transition. The introduction of directional micropores increased the swelling ratio below the transition and decreased the swelling ratio above the transition, thereby also enhancing the volume transition. Additionally, the formation of aligned micropores achieved fast water infiltration, which is beneficial for superabsorbent applications. The introduction of aligned micropores reduced the elastic modulus, but this could partially be compensated for by reinforcement with MFC. This combination of crystalline nanofibers and aligned micropores has great potential for the development of stimuli-responsive superporous hydrogels outperforming current artificial hydrogels. Copyright © 2014 Elsevier Ltd. All rights reserved.

Physicochemical properties and in vitro digestibility of sorghum starch altered by high hydrostatic pressure.

PubMed

Liu, Hang; Fan, Huanhuan; Cao, Rong; Blanchard, Christopher; Wang, Min

2016-11-01

A nonthermal processing technology, high hydrostatic pressure (HHP) treatment, was investigated to assess its influence on the physicochemical properties and in vitro digestibility of sorghum starch (SS). There was no change in the 'A'-type crystalline pattern of SS after the pressure treatments at 120-480MPa. However, treatment at 600MPa produced a pattern similar to 'B'-type crystalline. HHP treatment also resulted in SS granules with rough surfaces. Measured amylose content, water absorption capacity, alkaline water retention, pasting temperature and thermostability increased with increasing pressure levels, while the oil absorption capacity, swelling power, relative crystallinity and viscosity decreased. Compared with native starch, HHP-modified SS samples had lower in vitro hydrolysis, reduced amount of rapidly digestible starch, as well as increased levels of slowly digestible starch and resistant starch. These results indicate that HHP treatment is an effective modification method for altering in vitro digestibility and physicochemical properties of SS. Copyright © 2016 Elsevier B.V. All rights reserved.

PATHOGENESIS OF OPTIC DISC EDEMA IN RAISED INTRACRANIAL PRESSURE

PubMed Central

Hayreh, Sohan Singh

2015-01-01

Optic disc edema in raised intracranial pressure was first described in 1853. Ever since, there has been a plethora of controversial hypotheses to explain its pathogenesis. I have explored the subject comprehensively by doing basic, experimental and clinical studies. My objective was to investigate the fundamentals of the subject, to test the validity of the previous theories, and finally, based on all these studies, to find a logical explanation for the pathogenesis. My studies included the following issues pertinent to the pathogenesis of optic disc edema in raised intracranial pressure: the anatomy and blood supply of the optic nerve, the roles of the sheath of the optic nerve, of the centripetal flow of fluids along the optic nerve, of compression of the central retinal vein, and of acute intracranial hypertension and its associated effects. I found that, contrary to some previous claims, an acute rise of intracranial pressure was not quickly followed by production of optic disc edema. Then, in rhesus monkeys, I produced experimentally chronic intracranial hypertension by slowly increasing in size space-occupying lesions, in different parts of the brain. Those produced raised cerebrospinal fluid pressure (CSFP) and optic disc edema, identical to those seen in patients with elevated CSFP. Having achieved that, I investigated various aspects of optic disc edema by ophthalmoscopy, stereoscopic color fundus photography and fluorescein fundus angiography, and light microscopic, electron microscopic, horseradish peroxidase and axoplasmic transport studies, and evaluated the effect of opening the sheath of the optic nerve on the optic disc edema. This latter study showed that opening the sheath resulted in resolution of optic disc edema on the side of the sheath fenestration, in spite of high intracranial CSFP, proving that a rise of CSFP in the sheath was the essential pre-requisite for the development of optic disc edema. I also investigated optic disc edema with raised CSFP in patients, by evaluating optic disc and fundus changes by stereoscopic fundus photography and fluorescein fundus angiography. Based on the combined information from all the studies discussed above, it is clear that the pathogenesis of optic disc edema in raised intracranial pressure is a mechanical phenomenon. It is primarily due to a rise of CSFP in the optic nerve sheath, which produces axoplasmic flow stasis in the optic nerve fibers in the surface nerve fiber layer and prelaminar region of the optic nerve head. Axoplasmic flow stasis then results in swelling of the nerve fibers, and consequently of the optic disc. Swelling of the nerve fibers and of the optic disc secondarily compresses the fine, low-pressure venules in that region, resulting in venous stasis and fluid leakage; that leads to the accumulation of extracellular fluid. Contrary to the previous theories, the various vascular changes seen in optic disc edema are secondary and not primary. Thus, optic disc edema in raised CSFP is due to a combination of swollen nerve fibers and the accumulation of extracellular fluid. My studies also provided information about the pathogeneses of visual disturbances in raised intracranial pressure. PMID:26453995

Pathogenesis of optic disc edema in raised intracranial pressure.

PubMed

Hayreh, Sohan Singh

2016-01-01

Optic disc edema in raised intracranial pressure was first described in 1853. Ever since, there has been a plethora of controversial hypotheses to explain its pathogenesis. I have explored the subject comprehensively by doing basic, experimental and clinical studies. My objective was to investigate the fundamentals of the subject, to test the validity of the previous theories, and finally, based on all these studies, to find a logical explanation for the pathogenesis. My studies included the following issues pertinent to the pathogenesis of optic disc edema in raised intracranial pressure: the anatomy and blood supply of the optic nerve, the roles of the sheath of the optic nerve, of the centripetal flow of fluids along the optic nerve, of compression of the central retinal vein, and of acute intracranial hypertension and its associated effects. I found that, contrary to some previous claims, an acute rise of intracranial pressure was not quickly followed by production of optic disc edema. Then, in rhesus monkeys, I produced experimentally chronic intracranial hypertension by slowly increasing in size space-occupying lesions, in different parts of the brain. Those produced raised cerebrospinal fluid pressure (CSFP) and optic disc edema, identical to those seen in patients with elevated CSFP. Having achieved that, I investigated various aspects of optic disc edema by ophthalmoscopy, stereoscopic color fundus photography and fluorescein fundus angiography, and light microscopic, electron microscopic, horseradish peroxidase and axoplasmic transport studies, and evaluated the effect of opening the sheath of the optic nerve on the optic disc edema. This latter study showed that opening the sheath resulted in resolution of optic disc edema on the side of the sheath fenestration, in spite of high intracranial CSFP, proving that a rise of CSFP in the sheath was the essential pre-requisite for the development of optic disc edema. I also investigated optic disc edema with raised CSFP in patients, by evaluating optic disc and fundus changes by stereoscopic fundus photography and fluorescein fundus angiography. Based on the combined information from all the studies discussed above, it is clear that the pathogenesis of optic disc edema in raised intracranial pressure is a mechanical phenomenon. It is primarily due to a rise of CSFP in the optic nerve sheath, which produces axoplasmic flow stasis in the optic nerve fibers in the surface nerve fiber layer and prelaminar region of the optic nerve head. Axoplasmic flow stasis then results in swelling of the nerve fibers, and consequently of the optic disc. Swelling of the nerve fibers and of the optic disc secondarily compresses the fine, low-pressure venules in that region, resulting in venous stasis and fluid leakage; that leads to the accumulation of extracellular fluid. Contrary to the previous theories, the various vascular changes seen in optic disc edema are secondary and not primary. Thus, optic disc edema in raised CSFP is due to a combination of swollen nerve fibers and the accumulation of extracellular fluid. My studies also provided information about the pathogeneses of visual disturbances in raised intracranial pressure. Copyright © 2015 Elsevier Ltd. All rights reserved.

Maxillary bone epithelial cyst in an adult miniature schnauzer.

PubMed

Lin, Chung-Tien; Tasi, Wen-Chih; Hu, Chun-Kun; Lin, Nien-Ting; Huang, Pei-Yun; Yeh, Lih-Seng

2008-09-01

Maxillary bone epithelial cyst is rare in dogs. A 5-year-old, spayed female miniature schnauzer developed a swelling below the nasal canthus of left eye. Plain radiograph demonstrated a 1.5 cm diameter of radiolucent lesion on the maxillary bone anteroventral to the eye, and contrast dacryocystorhinography confirmed an obstructed nasolarcrimal duct. The swelling showed poor response to antibiotic treatment but responded well to oral prednisolone. Exploratory surgery revealed a cyst-like structure filled with brown serous fluid. Histopathological examination of the removed cyst revealed a double cuboidal epithelial cyst. The dog recovered rapidly after surgery, and the swelling had not recurred for a 36-month follow-up. It is the first case of periorbital bone epithelial cyst reported in an adult miniature schnauzer.

Acute compartment syndrome caused by uncontrolled hypothyroidism.

PubMed

Modi, Anar; Amin, Hari; Salzman, Matthew; Morgan, Farah

2017-06-01

Acute compartment syndrome is increased tissue pressure exceeding perfusion pressure in a closed compartment resulting in nerve and muscle ischemia. Common precipitating causes are crush injuries, burns, substance abuse, osseous or vascular limb trauma. This is a case of 42year old female with history of hypothyroidism who presented to emergency room with acute onset of severe pain and swelling in right lower extremity. Physical examination was concerning for acute compartment syndrome of right leg which was confirmed by demonstration of elevated compartmental pressures. No precipitating causes were readily identified. Further laboratory testing revealed uncontrolled hypothyroidism. Management included emergent fasciotomy and initiating thyroid hormone replacement. This case represents a rare association between acute compartment syndrome and uncontrolled hypothyroidism. We also discuss the pathogenesis of compartment syndrome in hypothyroid patients and emphasize the importance of evaluating for less common causes, particularly in setting of non-traumatic compartment syndrome. Copyright © 2016 Elsevier Inc. All rights reserved.

Swelling and tribological properties of melt-mixed fluoroelastomer/nitrile rubber blends under crude oil

NASA Astrophysics Data System (ADS)

Tagelsir, Yasin; Li, San-Xi; Lv, Xiaoren; Wang, Shijie; Wang, Song; Osman, Zeinab

2018-01-01

The melt-mixed fluoroelastomer (FKM)/ nitrile rubber (NBR) blends of (90/10, 80/20, 70/30, 60/40 and 50/50) ratios with same hardness were prepared, and their swelling and tribological properties under crude oil were investigated for the purpose of developing high performance cost-effective elastomers meeting requirement of oil extraction progressive cavity pump stator. Differential scanning calorimetry confirmed compatible blend system for all blends. Field emission scanning electron microscopy (FE-SEM) showed co-continuous morphology of 200-400 nm phase size for all blends, expect FKM/NBR (90/10) which exhibited partially continuous phase morphology of 100-250 nm phase size. The results of swelling and linear wear tests under crude oil indicated that swelling percentage, coefficient of friction and specific wear rate of FKM/NBR blends were much better than NBR, with FKM/NBR (90/10 and 80/20) showing swelling percentage and specific wear rate very close to FKM. Attenuated total reflectance-Fourier transform infrared spectroscopy disclosed that fracture of macromolecular chains was the main mechanochemical effect of unswollen and swollen worn surfaces, in addition to oxygenated degradation detected with increasing NBR ratio in the blends. The fracture of macromolecular chains resulted in slight fatigue wear mechanism, which was also confirmed by FE-SEM of the worn surfaces.

Contribution to irradiation creep arising from gas-driven bubbles

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

Woo, C.H.; Garner, F.A.

1998-03-01

In a previous paper the relationship was defined between void swelling and irradiation creep arising from the interaction of the SIPA and SIG creep-driven deformation and swelling-driven deformation was highly interactive in nature, and that the two contributions could not be independently calculated and then considered as directly additive. This model could be used to explain the recent experimental observation that the creep-swelling coupling coefficient was not a constant as previously assumed, but declined continuously as the swelling rate increased. Such a model thereby explained the creep-disappearance and creep-damping anomalies observed in conditions where significant void swelling occurred before substantialmore » creep deformation developed. At lower irradiation temperatures and high helium/hydrogen generation rates, such as found in light water cooled reactors and some fusion concepts, gas-filled cavities that have not yet exceeded the critical radius for bubble-void conversion should also exert an influence on irradiation creep. In this paper the original concept is adapted to include such conditions, and its predictions then compared with available data. It is shown that a measurable increase in the creep rate is expected compared to the rate found in low gas-generating environments. The creep rate is directly related to the gas generation rate and thereby to the neutron flux and spectrum.« less

Mechanics of interstitial-lymphatic fluid transport: theoretical foundation and experimental validation.

PubMed

Swartz, M A; Kaipainen, A; Netti, P A; Brekken, C; Boucher, Y; Grodzinsky, A J; Jain, R K

1999-12-01

Interstitial fluid movement is intrinsically linked to lymphatic drainage. However, their relationship is poorly understood, and associated pathologies are mostly untreatable. In this work we test the hypothesis that bulk tissue fluid movement can be evaluated in situ and described by a linear biphasic theory which integrates the regulatory function of the lymphatics with the mechanical stresses of the tissue. To accomplish this, we develop a novel experimental and theoretical model using the skin of the mouse tail. We then use the model to demonstrate how interstitial-lymphatic fluid movement depends on a balance between the elasticity, hydraulic conductivity, and lymphatic conductance as well as to demonstrate how chronic swelling (edema) alters the equipoise between tissue fluid balance parameters. Specifically, tissue fluid equilibrium is perturbed with a continuous interstitial infusion of saline into the tip of the tail. The resulting gradients in tissue stress are measured in terms of interstitial fluid pressure using a servo-null system. These measurements are then fit to the theory to provide in vivo estimates of the tissue hydraulic conductivity, elastic modulus, and overall resistance to lymphatic drainage. Additional experiments are performed on edematous tails to show that although chronic swelling causes an increase in the hydraulic conductivity, its greatly increased distensibility (due to matrix remodeling) dampens the driving forces for fluid movement and leads to fluid stagnation. This model is useful for examining potential treatments for edema and lymphatic disorders as well as substances which may alter tissue fluid balance and/or lymphatic drainage.

Spinal Cord Swelling and Alterations in Hydrostatic Pressure After Acute Injury

DTIC Science & Technology

2017-10-01

finalized and reported on the metabolite responses data over a 7-day period with or without duraplasty surgery. Eight female Yucatan pigs, weighing 29-34...Control 8371 Badminton Yucatan Contusion: 50gr/20cm Compression : 150gr/5min 3227.00 33.0 2016-09-06 Control 8372 Diving Yucatan 2154.00 34.0 2016...09-21 Control 8437 Gymnastics Yucatan 2538.00 32.0 2016-09-27 Control 8400 Heptathlon Yucatan 2539.00 34.0 SX date Group ID# Name Species Injury

Updated Lagrangian finite element formulations of various biological soft tissue non-linear material models: a comprehensive procedure and review.

PubMed

Townsend, Molly T; Sarigul-Klijn, Nesrin

2016-01-01

Simplified material models are commonly used in computational simulation of biological soft tissue as an approximation of the complicated material response and to minimize computational resources. However, the simulation of complex loadings, such as long-duration tissue swelling, necessitates complex models that are not easy to formulate. This paper strives to offer the updated Lagrangian formulation comprehensive procedure of various non-linear material models for the application of finite element analysis of biological soft tissues including a definition of the Cauchy stress and the spatial tangential stiffness. The relationships between water content, osmotic pressure, ionic concentration and the pore pressure stress of the tissue are discussed with the merits of these models and their applications.

Development and Implementation of the National Test Facility (NaTeF) for Fuels and Propulsion

DTIC Science & Technology

2013-10-01

permanent indentation. This equipment is used in the Materials Laboratory to determine hardness in polymers, elastomers, and rubbers , characteristics...impacted by exposure to synthetic fuels was the nitrile rubber , one of the materials selected for this research. Further research found a relationship...Similarly, as the molecular weight decreased, the volume swell increased. Therefore, it is indicated that the greatest swell in nitrile rubber will be

Validation and Parameter Sensitivity Tests for Reconstructing Swell Field Based on an Ensemble Kalman Filter

PubMed Central

Wang, Xuan; Tandeo, Pierre; Fablet, Ronan; Husson, Romain; Guan, Lei; Chen, Ge

2016-01-01

The swell propagation model built on geometric optics is known to work well when simulating radiated swells from a far located storm. Based on this simple approximation, satellites have acquired plenty of large samples on basin-traversing swells induced by fierce storms situated in mid-latitudes. How to routinely reconstruct swell fields with these irregularly sampled observations from space via known swell propagation principle requires more examination. In this study, we apply 3-h interval pseudo SAR observations in the ensemble Kalman filter (EnKF) to reconstruct a swell field in ocean basin, and compare it with buoy swell partitions and polynomial regression results. As validated against in situ measurements, EnKF works well in terms of spatial–temporal consistency in far-field swell propagation scenarios. Using this framework, we further address the influence of EnKF parameters, and perform a sensitivity analysis to evaluate estimations made under different sets of parameters. Such analysis is of key interest with respect to future multiple-source routinely recorded swell field data. Satellite-derived swell data can serve as a valuable complementary dataset to in situ or wave re-analysis datasets. PMID:27898005

Modeling Scala Media as a Pressure Vessel

NASA Astrophysics Data System (ADS)

Lepage, Eric; Olofsson, A.˚Ke

2011-11-01

The clinical condition known as endolymphatic hydrops is the swelling of scala media and may result in loss in hearing sensitivity consistent with other forms of low-frequency biasing. Because outer hair cells (OHCs) are displacement-sensitive and hearing levels tend to be preserved despite large changes in blood pressure and CSF pressure, it seems unlikely that the OHC respond passively to changes in static pressures in the chambers. This suggests the operation of a major feedback control loop which jointly regulates homeostasis and hearing sensitivity. Therefore the internal forces affecting the cochlear signal processing amplifier cannot be just motile responses. A complete account of the cochlear amplifier must include static pressures. To this end we have added a third, pressure vessel to our 1-D 140-segment, wave-digital filter active model of cochlear mechanics, incorporating the usual nonlinear forward transduction. In each segment the instantaneous pressure is the sum of acoustic pressure and global static pressure. The object of the model is to maintain stable OHC operating point despite any global rise in pressure in the third chamber. Such accumulated pressure is allowed to dissipate exponentially. In this first 3-chamber implementation we explore the possibility that acoustic pressures are rectified. The behavior of the model is critically dependent upon scaling factors and time-constants, yet by initial assumption, the pressure tends to accumulate in proportion to sound level. We further explore setting of the control parameters so that the accumulated pressure either stays within limits or may rise without bound.

Magnetic resonance imaging (MRI) and relaxation spectrum analysis as methods to investigate swelling in whey protein gels.

PubMed

Oztop, Mecit H; Rosenberg, Moshe; Rosenberg, Yael; McCarthy, Kathryn L; McCarthy, Michael J

2010-10-01

Effective means for controlled delivery of nutrients and nutraceuticals are needed. Whey protein-based gels, as a model system and as a potential delivery system, exhibit pH-dependent swelling when placed in aqueous solutions. Understanding the physics that govern gel swelling is thus important when designing gel-based delivery platforms. The extent of swelling over time was monitored gravimetrically. In addition to gravimetric measurements, magnetic resonance imaging (MRI) a real-time noninvasive imaging technique that quantified changes in geometry and water content of these gels was utilized. Heat-set whey protein gels were prepared at pH 7 and swelling was monitored in aqueous solutions with pH values of 2.5, 7, and 10. Changes in dimension over time, as characterized by the number of voxels in an image, were correlated to gravimetric measurements. Excellent correlations between mass uptake and volume change (R(2)= 0.99) were obtained for the gels in aqueous solutions at pH 7 and 10, but not for gels in the aqueous solution at pH 2.5. To provide insight into the mechanisms for water uptake, nuclear magnetic resonance (NMR) relaxation times were measured in independent experiments. The relaxation spectrum for the spin-spin relaxation time (T(2)) showed the presence of 3 proton pools for pH 7 and 10 trials and 4 proton pools for pH 2.5 trials. Results demonstrate that MRI and NMR relaxation measurements provided information about swelling in whey protein gels that can constitute a new means for investigating and developing effective delivery systems for foods.

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

Gigax, J. G.; Chen, T.; Kim, Hyosim

Ferritic/martensitic alloys are required for advanced reactor components to survive 500–600 neutron-induced dpa. In this paper, ion-induced void swelling of ferritic/martensitic alloy T91 in the quenched and tempered condition has been studied using a defocused, non-rastered 3.5 MeV Fe-ion beam at 475 °C to produce damage levels up to 1000 peak displacements per atom (dpa). The high peak damage level of 1000 dpa is required to reach 500–600 dpa level due to injected interstitial suppression of void nucleation in the peak dpa region, requiring data extraction closer to the surface at lower dpa levels. At a relatively low peak damagemore » level of 250 dpa, voids began to develop, appearing first in the near-surface region. With increasing ion fluence, swelling was observed deeper in the specimen, but remained completely suppressed in the back half of the ion range, even at 1000 peak dpa. The local differences in dpa rate in the front half of the ion range induce an “internal temperature shift” that strongly influences the onset of swelling, with shorter transient regimes resulting from lower dpa rates, in agreement not only with observations in neutron irradiation studies but also in various ion irradiations. Swelling was accompanied by radiation-induced precipitation of Cu-rich and Si, Ni, Mn-rich phases were observed by atom probe tomography, indicating concurrent microchemical evolution was in progress. Finally, in comparison to other ferritic/martensitic alloys during ion irradiation, T91 exhibits good swelling resistance with a swelling incubation period of about 400 local dpa.« less

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

Gigax, J. G.; Chen, T.; Kim, Hyosim

Ferritic/martensitic alloys are required for advanced reactor components to survive 500e600 neutroninduced dpa. Ion-induced void swelling of ferritic/martensitic alloy T91 in the quenched and tempered condition has been studied using a defocused, non-rastered 3.5 MeV Fe-ion beam at 475 C to produce damage levels up to 1000 peak displacements per atom (dpa). The high peak damage level of 1000 dpa is required to reach 500e600 dpa level due to injected interstitial suppression of void nucleation in the peak dpa region, requiring data extraction closer to the surface at lower dpa levels. At a relatively low peak damage level of 250more » dpa, voids began to develop, appearing first in the near-surface region. With increasing ion fluence, swelling was observed deeper in the specimen, but remained completely suppressed in the back half of the ion range, even at 1000 peak dpa. The local differences in dpa rate in the front half of the ion range induce an “internal temperature shift” that strongly influences the onset of swelling, with shorter transient regimes resulting from lower dpa rates, in agreement not only with observations in neutron irradiation studies but also in various ion irradiations. Swelling was accompanied by radiation-induced precipitation of Cu-rich and Si, Ni, Mn-rich phases were observed by atom probe tomography, indicating concurrent microchemical evolution was in progress. In comparison to other ferritic/martensitic alloys during ion irradiation, T91 exhibits good swelling resistance with a swelling incubation period of about 400 local dpa.« less

Foot, leg, and ankle swelling

MedlinePlus

... feet - legs; Ankle swelling; Foot swelling; Leg swelling; Edema - peripheral; Peripheral edema ... 31. Trayes KP, Studdiford JS, Pickle S, Tully AS. Edema: diagnosis and management. Am Fam Physician . 2013;88( ...

Stimuli-sensitive hydrogels: an excellent carrier for drug and cell delivery.

PubMed

Garg, Tarun; Singh, Simranjit; Goyal, Amit Kumar

2013-01-01

The stimuli-sensitive hydrogel is an injectable formulation that is used to deliver drugs, cells, and genes into the body. Hydrogels are available in various physical forms such as solid molded, pressed powder matrix, microparticle, coating, or membrane forms. The network structure of hydrogels can be macroporous, microporous, or nonporous. Different categories of biomaterials, such as natural, synthetic, and combinations (e.g., semisynthetic such as natural-natural, natural-synthetic, and synthetic-synthetic polymers), are commonly used in hydrogel preparation. Classification of hydrogels mainly depends upon physical stimuli (temperature, electric fields, solvent composition, light, pressure, sound, and magnetic fields) and chemical or biochemical stimuli (pH, ions, and specific molecular recognition events). Several approaches for the synthesis of hydrogels have been reported, including emulsification, micromolding, photolithography, isostatic ultra high pressure, and microfluidic techniques. Hydrogels provide structural integrity and cellular organization, serve as tissue barriers, act as bioadhesive and drug depots, deliver bioactive agents and cells, and possess unique swelling properties and structures. This review provides a detailed account of the need for development of hydrogels, along with the materials used and techniques adopted to manufacture scaffolds for tissue engineering and for prolonged drug, cell, and gene delivery.

Processes and controls in swelling anhydritic clay rocks

NASA Astrophysics Data System (ADS)

Mutschler, Thomas; Blum, Philipp; Butscher, Christoph

2015-04-01

Referring to the swelling of anhydritic clay rocks in tunneling, Leopold Müller-Salzburg noted in the third volume on tunneling of his fundamental text book on rock engineering that "a truly coherent explanation of these phenomena is still owing" (Müller-Salzburg 1978, p. 306). This valuation is still true after more than three decades of research in the field of swelling anhydritic clay rocks. One of the reasons is our limited knowledge of the processes involved in the swelling of such rocks, and of the geological, mineralogical, hydraulic, chemical and mechanical controls of the swelling. In this contribution, a review of processes in swelling anhydritic clay rocks and of associated controls is presented. Also numerical models that aim at simulating the swelling processes and controls are included in this review, and some of the remaining open questions are pointed out. By focusing on process-oriented work in this review, the presentation intends to stimulate further research across disciplines in the field of swelling anhydritic clay rocks to finally get a step further in managing the swelling problem in geotechnical engineering projects. Keywords: swelling; anhydritic clay rocks; review

Hydro-mechanical model for wetting/drying and fracture development in geomaterials

DOE PAGES

Asahina, D.; Houseworth, J. E.; Birkholzer, J. T.; ...

2013-12-28

This study presents a modeling approach for studying hydro-mechanical coupled processes, including fracture development, within geological formations. This is accomplished through the novel linking of two codes: TOUGH2, which is a widely used simulator of subsurface multiphase flow based on the finite volume method; and an implementation of the Rigid-Body-Spring Network (RBSN) method, which provides a discrete (lattice) representation of material elasticity and fracture development. The modeling approach is facilitated by a Voronoi-based discretization technique, capable of representing discrete fracture networks. The TOUGH–RBSN simulator is intended to predict fracture evolution, as well as mass transport through permeable media, under dynamicallymore » changing hydrologic and mechanical conditions. Numerical results are compared with those of two independent studies involving hydro-mechanical coupling: (1) numerical modeling of swelling stress development in bentonite; and (2) experimental study of desiccation cracking in a mining waste. The comparisons show good agreement with respect to moisture content, stress development with changes in pore pressure, and time to crack initiation. Finally, the observed relationship between material thickness and crack patterns (e.g., mean spacing of cracks) is captured by the proposed modeling approach.« less

Case of cheilitis granulomatosa associated with apical periodontitis.

PubMed

Kawakami, Tomoko; Fukai, Kazuyoshi; Sowa, Junko; Ishii, Masamitsu; Teramae, Hiroyuki; Kanazawa, Koutetsu

2008-02-01

The etiology of cheilitis granulomatosa is unknown. In some cases, rapid improvement and/or complete elimination of swelling of the lips after dental treatment has been reported. Here, we describe another case of improvement following dental treatment. A 57-year-old woman had developed asymptomatic swelling of the lower lip 2 months previously. Histological examination revealed non-caseous giant cell granulomas. Neither facial nerve palsy nor fissuring of the tongue was present. Patch testing for metal allergy revealed only mild irritation to zinc ion. Although topical corticosteroid ointment and oral tranilast for 4 months were ineffective, rapid and remarkable improvement of the swelling was noted soon after treatment of two lesions of apical periodontitis. Thorough examination for foci of infection is necessary when treating a patient with cheilitis granulomatosa.

Anisotropic Swelling and Fracture of Silicon Nanowires during Lithiation

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

Liu, Xiao Hua; Zheng, He; Zhong, Li

2011-08-10

We report direct observation of an unexpected anisotropic swelling of Si nanowires during lithiation against either a solid electrolyte with a lithium counter-electrode or a liquid electrolyte with a LiCoO2 counter-electrode. Such anisotropic expansion is attributed to the interfacial processes of accommodating large volumetric strains at the lithiation reaction front that depend sensitively on the crystallographic orientation. This anisotropic swelling results in lithiated Si nanowires with a remarkable dumbbell-shaped cross section, which develops due to plastic flow and an ensuing necking instability that is induced by the tensile hoop stress buildup in the lithiated shell. The plasticity-driven morphological instabilities oftenmore » lead to fracture in lithiated nanowires, now captured in video. These results provide important insight into the battery degradation mechanisms.« less

Swell Sleeves for Testing Explosive Devices

NASA Technical Reports Server (NTRS)

Hinkel, Todd J.; Dean, Richard J.; Hohmann, Carl W.; Hacker, Scott C.; Harrington, Douglas W.; Bacak, James W.

2003-01-01

A method of testing explosive and pyrotechnic devices involves exploding the devices inside swell sleeves. Swell sleeves have been used previously for measuring forces. In the present method, they are used to obtain quantitative indications of the energy released in explosions of the devices under test. A swell sleeve is basically a thick-walled, hollow metal cylinder threaded at one end to accept a threaded surface on a device to be tested (see Figure 1). Once the device has been tightly threaded in place in the swell sleeve, the device-and-swell-sleeve assembly is placed in a test fixture, then the device is detonated. After the explosion, the assembly is removed from the test fixture and placed in a coordinate-measuring machine for measurement of the diameter of the swell sleeve as a function of axial position. For each axial position, the original diameter of the sleeve is subtracted from the diameter of the sleeve as swollen by the explosion to obtain the diametral swelling as a function of axial position (see Figure 2). The amount of swelling is taken as a measure of the energy released in the explosion. The amount of swelling can be compared to a standard amount of swelling to determine whether the pyrotechnic device functioned as specified.

Common symptoms during pregnancy

MedlinePlus

... keep your gums healthy Swelling, Varicose Veins, and Hemorrhoids Swelling in your legs is common. You may ... In your rectum, veins that swell are called hemorrhoids. To reduce swelling: Raise your legs and rest ...

Management of venomous snakebite injury to the extremities.

PubMed

Anz, Adam W; Schweppe, Mark; Halvorson, Jason; Bushnell, Brandon; Sternberg, Michael; Andrew Koman, L

2010-12-01

Pit vipers (subfamily Crotalinae) are responsible for most venomous snakebites in the United States. The mixture of proteins with cytotoxic, proteolytic, and/or neurotoxic enzymes in snake venom varies by species. Treatment in the field consists of safe identification of the species of snake and rapid transport of the patient to the nearest health care facility. Swelling, bruising, and systemic symptoms are seen following snakebite. Most patients respond to elevation of the affected extremity and observation. Some require the administration of antivenin. Crotalidae Polyvalent Immune Fab (Ovine) (CroFab, BTG International, West Conshohocken, PA) antivenin is safe and effective for the management of local and systemic effects of envenomation. Rarely, compartment syndrome may develop in the affected limb because of edema and tissue necrosis. Close monitoring of the extremity via serial physical examination and measurement of compartment pressure is a reliable method of determining whether surgical intervention is required.

Cyclodialysis: an update.

PubMed

González-Martín-Moro, Julio; Contreras-Martín, Inés; Muñoz-Negrete, Francisco José; Gómez-Sanz, Fernando; Zarallo-Gallardo, Jesús

2017-04-01

Cyclodialysis is the result of the separation of the longitudinal ciliary muscle fibers from the scleral spur, which creates an abnormal pathway for aqueous humor drainage that may lead to ocular hypotony. For many years cyclodialysis was considered a treatment option for glaucoma. However, today it usually occurs as a complication of blunt trauma or more rarely as a complication of anterior segment ocular surgery. Ocular hypotony can lead to cataract development, optic disk swelling, refractive changes, and several retinal complications, making accurate identification and timely intervention of the cleft mandatory. Traditionally gonioscopy was the only available technique to diagnose and localize the cleft. However, other tests such as optical coherence tomography, magnetic resonance imaging, transillumination, and specially ultrasound biomicroscopy are now available for the diagnosis of cyclodialysis. Multiple treatment options are also available for this condition. Although medical treatment can be effective to close small clefts, surgery is needed in most patients to restore ocular pressure.

Forskolin-induced Swelling in Intestinal Organoids: An In Vitro Assay for Assessing Drug Response in Cystic Fibrosis Patients.

PubMed

Boj, Sylvia F; Vonk, Annelotte M; Statia, Marvin; Su, Jinyi; Vries, Robert R G; Beekman, Jeffrey M; Clevers, Hans

2017-02-11

Recently-developed cystic fibrosis transmembrane conductance regulator (CFTR)-modulating drugs correct surface expression and/or function of the mutant CFTR channel in subjects with cystic fibrosis (CF). Identification of subjects that may benefit from these drugs is challenging because of the extensive heterogeneity of CFTR mutations, as well as other unknown factors that contribute to individual drug efficacy. Here, we describe a simple and relatively rapid assay for measuring individual CFTR function and response to CFTR modulators in vitro. Three dimensional (3D) epithelial organoids are grown from rectal biopsies in standard organoid medium. Once established, the organoids can be bio-banked for future analysis. For the assay, 30-80 organoids are seeded in 96-well plates in basement membrane matrix and are then exposed to drugs. One day later, the organoids are stained with calcein green, and forskolin-induced swelling is monitored by confocal live cell microscopy at 37 °C. Forskolin-induced swelling is fully CFTR-dependent and is sufficiently sensitive and precise to allow for discrimination between the drug responses of individuals with different and even identical CFTR mutations. In vitro swell responses correlate with the clinical response to therapy. This assay provides a cost-effective approach for the identification of drug-responsive individuals, independent of their CFTR mutations. It may also be instrumental in the development of future CFTR modulators.

An improved correlation to predict molecular weight between crosslinks based on equilibrium degree of swelling of hydrogel networks.

PubMed

Jimenez-Vergara, Andrea C; Lewis, John; Hahn, Mariah S; Munoz-Pinto, Dany J

2018-04-01

Accurate characterization of hydrogel diffusional properties is of substantial importance for a range of biotechnological applications. The diffusional capacity of hydrogels has commonly been estimated using the average molecular weight between crosslinks (M c ), which is calculated based on the equilibrium degree of swelling. However, the existing correlation linking M c and equilibrium swelling fails to accurately reflect the diffusional properties of highly crosslinked hydrogel networks. Also, as demonstrated herein, the current model fails to accurately predict the diffusional properties of hydrogels when polymer concentration and molecular weight are varied simultaneously. To address these limitations, we evaluated the diffusional properties of 48 distinct hydrogel formulations using two different photoinitiator systems, employing molecular size exclusion as an alternative methodology to calculate average hydrogel mesh size. The resulting data were then utilized to develop a revised correlation between M c and hydrogel equilibrium swelling that substantially reduces the limitations associated with the current correlation. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1339-1348, 2018. © 2017 Wiley Periodicals, Inc.

Snoring-Induced Vibratory Angioedema.

PubMed

Kalathoor, Ipe

2015-10-01

Vibratory angioedema (VA) is a rare physical urticaria, with symptoms of itching and swelling of the skin or mucosa when it is exposed to vibration. Avoidance of vibration is the best way to manage this condition. This case report will assist physicians to diagnose this rare condition. Here, a previously unpublished potential successful treatment modality is being presented, with good symptom control, along with some photographs taken during an acute attack. A literature review points towards potential undiagnosed cases. A 70-year-old woman had multiple emergency department visits for tongue and throat swelling over 3 years. The episodes always happened at night. Detailed history elicited some episodes of itching and swelling of hands when driving as well as significant snoring while sleeping. Physical examination was unremarkable except for morbid obesity. Complement factor 4 and C1esterase inhibitor level were within normal limits. A tentative diagnosis of angioedema induced by oropharyngeal vibration from snoring was made. A sleep study confirmed sleep apnea with severe snoring. After CPAP (continuous positive airway pressure) treatment, she had successful symptom control. Snoring-induced VA is very likely an under-diagnosed condition in the community. The typical history is the key to the diagnosis. This condition could be confirmed by vibration test or by the resolution of symptoms with elimination of vibration. Effective symptom control is possible by avoidance of oropharyngeal vibration from snoring with the administration of CPAP therapy, making it a potential novel indication for this condition.

Differences in time-dependent mechanical properties between extruded and molded hydrogels

PubMed Central

Ersumo, N; Witherel, CE; Spiller, KL

2016-01-01

The mechanical properties of hydrogels used in biomaterials and tissue engineering applications are critical determinants of their functionality. Despite the recent rise of additive manufacturing, and specifically extrusion-based bioprinting, as a prominent biofabrication method, comprehensive studies investigating the mechanical behavior of extruded constructs remain lacking. To address this gap in knowledge, we compared the mechanical properties and swelling properties of crosslinked gelatin-based hydrogels prepared by conventional molding techniques or by 3D bioprinting using a BioBots Beta pneumatic extruder. A preliminary characterization of the impact of bioprinting parameters on construct properties revealed that both Young's modulus and optimal extruding pressure increased with polymer content, and that printing resolution increased with both printing speed and nozzle gauge. High viability (>95%) of encapsulated NIH 3T3 fibroblasts confirmed the cytocompatibility of the construct preparation process. Interestingly, the Young's moduli of extruded and molded constructs were not different, but extruded constructs did show increases in both the rate and extent of time-dependent mechanical behavior observed in creep. Despite similar polymer densities, extruded hydrogels showed greater swelling over time compared to molded hydrogels, suggesting that differences in creep behavior derived from differences in microstructure and fluid flow. Because of the crucial roles of time-dependent mechanical properties, fluid flow, and swelling properties on tissue and cell behavior, these findings highlight the need for greater consideration of the effects of the extrusion process on hydrogel properties. PMID:27550945

Swelling/Floating Capability and Drug Release Characterizations of Gastroretentive Drug Delivery System Based on a Combination of Hydroxyethyl Cellulose and Sodium Carboxymethyl Cellulose

PubMed Central

Chen, Ying-Chen; Ho, Hsiu-O; Liu, Der-Zen; Siow, Wen-Shian; Sheu, Ming-Thau

2015-01-01

The aim of this study was to characterize the swelling and floating behaviors of gastroretentive drug delivery system (GRDDS) composed of hydroxyethyl cellulose (HEC) and sodium carboxymethyl cellulose (NaCMC) and to optimize HEC/NaCMC GRDDS to incorporate three model drugs with different solubilities (metformin, ciprofloxacin, and esomeprazole). Various ratios of NaCMC to HEC were formulated, and their swelling and floating behaviors were characterized. Influences of media containing various NaCl concentrations on the swelling and floating behaviors and drug solubility were also characterized. Finally, release profiles of the three model drugs from GRDDS formulation (F1-4) and formulation (F1-1) were examined. Results demonstrated when the GRDDS tablets were tested in simulated gastric solution, the degree of swelling at 6 h was decreased for each formulation that contained NaCMC in comparison to those in de-ionized water (DIW). Of note, floating duration was enhanced when in simulated gastric solution compared to DIW. Further, the hydration of tablets was found to be retarded as the NaCl concentration in the medium increased resulting in smaller gel layers and swelling sizes. Dissolution profiles of the three model drugs in media containing various concentrations of NaCl showed that the addition of NaCl to the media affected the solubility of the drugs, and also their gelling behaviors, resulting in different mechanisms for controlling a drug’s release. The release mechanism of the freely water-soluble drug, metformin, was mainly diffusion-controlled, while those of the water-soluble drug, ciprofloxacin, and the slightly water-soluble drug, esomeprazole, were mainly anomalous diffusion. Overall results showed that the developed GRDDS composed of HEC 250HHX and NaCMC of 450 cps possessed proper swelling extents and desired floating periods with sustained-release characteristics. PMID:25617891

Ultrasonic characterization of silicate glasses, polymer composites and hydrogels

NASA Astrophysics Data System (ADS)

Lee, Wan Jae

In many applications of material designing and engineering, high-frequency linear viscoelastic properties of materials are essential. Traditionally, the high-frequency properties are estimated through the time-temperature superposition (WLF equation) of low-frequency data, which are questionable because the existence of multi-phase in elastomer compounds. Moreover, no reliable data at high frequencies over MHz have been available thus far. Ultrasound testing is cost-effective for measuring high-frequency properties. Although both ultrasonic longitudinal and shear properties are necessary in order to fully characterize high-frequency mechanical properties of materials, longitudinal properties will be extensively explored in this thesis. Ultrasonic pulse echo method measures longitudinal properties. A precision ultrasonic measurement system has been developed in our laboratory, which allows us to monitor the in-situ bulk and/or surface properties of silicate glasses, polymer composites and even hydrogels. The system consists of a pulse-echo unit and an impedance measurement unit. A pulse echo unit is explored mainly. First, a systematic procedure was developed to obtain precise water wavespeed value. A calibration curve of water wavespeed as a function of temperature has been established, and water wavespeed at 23°C serves as a yardstick to tell whether or not a setup is properly aligned. Second, a sound protocol in calculating attenuation coefficient and beam divergence effects was explored using three kinds of silicate glass of different thicknesses. Then the system was applied to four composite slabs, two slabs for each type of fiberglass reinforced plastics, phenolic and polyester manufactured under different processing conditions: one was made by the normal procedures and the other with deliberate flaws such as voids, tapes and/or prepared at improper operation temperature and pressure. The experiment was conducted under the double blind test protocol. After carefully and methodically analyzing the data, we are able to detect defected specimens from all the specimens supplied to us, differentiate polyester-based composite from the phenolic-based composite and even recognized types of defects. Lastly, ultrasonic monitoring of advancement of the swollen-unswollen fronts, and hence monitor phase transition from glassy state to rubbery state, of poly(acrylic-acid) hydrogel of one of the three different crosslinking densities is performed. With ultrasonic measurement, swelling monitoring is possible since the structural and mechanical changes during swelling of a dry hydrogel are related to changes in density and elastic constants. Using our carefully developed methodology from previous chapters, we may obtain and monitor average acoustic properties of each layer of hydrogel as it swells.

Morphosedimentary evolution of carbonate sandy beaches at decadal scale : case study in Reunion Island , Indian Ocean

NASA Astrophysics Data System (ADS)

Mahabot, Marie-Myriam; Pennober, Gwenaelle; Suanez, Serge; Troadec, Roland; Delacourt, Christophe

2017-04-01

Global change introduce a lot of uncertainties concerning future trajectory of beaches by directly or indirectly modifying major driving factors. An improved understanding of the past shoreline evolution may help for anticipate future coastline response. However, in tropical environment, studies concerning carbonate beaches dynamics are scarce compared to open sandy beaches. Consequently, coral reef protected beaches morphological adjustment is still poorly understood and long-term evolution rate are poorly quantified in these specific environment. In this context, La Reunion Island, insular department of France located in Indian Ocean, constitute a favoured laboratory. This high volcanic island possesses 25 km of carbonate beaches which experience hydrodynamic forcing specific from tropical environment: cyclonic swell during summer and long period swell during winter. Because of degraded coral reef health and high anthropogenic pressure, 50% of the beaches are in erosion since 1970s. Beach survey has been conducted since 1990s by scientist and are now encompassed as pilot site within a French observatory network which guarantee long-term survey with high resolution observational techniques. Thus, La Reunion Island is one of the rare carbonate beach to be surveyed since 20 years. This study aims to examined and quantify beach response at decadal scale on carbonate sandy beaches of Reunion Island. The study focus on 12 km of beaches from Cap Champagne to the Passe de Trois-Bassins. The analyze of 15 beach profile data originated from historical and DGPS beach topographic data confirm long term trend to erosion. Sediment lost varies between 0.5 and 2 m3.yr-1 since 1998. However longshore current have led to accretion of some part of beach compartment with rate of 0.7 to 1.6 m3.yr-1. Wave climate was examined from in-situ measurement over 15 years and show that extreme waves associated with tropical cyclones and long period swell play a major role in beach dynamics. Swell frequency and intensity are both determinant for beach evolution.

Water Migration and Swelling in Bentonite Quantified using Neutron Radiography

NASA Astrophysics Data System (ADS)

Vial, A.; DiStefano, V. H.; Perfect, E.; Hale, R. E.; Anovitz, L. M.; McFarlane, J.

2016-12-01

Permanent disposal of radioactive waste remains a critical challenge for the nation's energy future. All disposal system concepts include interfaces between engineered systems and natural materials requiring extensive characterization. Bentonite is often used to buffer subsurface disposal systems from geologic media containing ground water. Bentonite characterization experiments were carried out using the CG-1D neutron imaging beam line at Oak Ridge National Laboratory. Dry bentonite was packed into vertically-oriented aluminum cylinders. Water was ponded on the top surface of each packed cylinder. Images were acquired at 2 min intervals using dynamic neutron radiography. The detector consisted of stacked neutron sensitive microchannel plates above a quad Timepix readout with a 28 x 28 mm2 field of view. The spatial resolution of the detector was 55 μm. Raw neutron radiographs were imported into ImageJ and normalized with respect to the initial completely dry state. The wetting process was 1-dimensional, and vertical intensity profiles were computed by averaging pixel rows. The vertical distance between the clay-water interface and the wetting front could then be determined as a function of time. Depth of water infiltration increased linearly with the square root of time, yielding a sorptivity value of 0.75 (± 0.070) mm/min0.5. Swelling occurred in the form of upward movement of clay particles into the ponded water over time. The resulting low density assemblage was discernable by normalizing the raw profiles with respect to the intensity profile immediately after ponding. The packed clay-water interface was clearly visible in the normalized profiles, and swelling was quantified as the height of the low density assemblage above the original interface. Swelling occurred as a linear function of time, at a rate of 0.054 (± 0.020) mm/min. Further experiments of this type are planned under variable temperature and pressure regimes applicable to subsurface repositories.

Carbohydrate gel beads as model probes for quantifying non-ionic and ionic contributions behind the swelling of delignified plant fibers.

PubMed

Karlsson, Rose-Marie Pernilla; Larsson, Per Tomas; Yu, Shun; Pendergraph, Samuel Allen; Pettersson, Torbjörn; Hellwig, Johannes; Wågberg, Lars

2018-06-01

Macroscopic beads of water-based gels consisting of uncharged and partially charged β-(1,4)-d-glucan polymers were developed to be used as a novel model material for studying the water induced swelling of the delignified plant fiber walls. The gel beads were prepared by drop-wise precipitation of solutions of dissolving grade fibers carboxymethylated to different degrees. The internal structure was analyzed using Solid State Cross-Polarization Magic Angle Spinning Carbon-13 Nuclear Magnetic Resonance and Small Angle X-ray Scattering showing that the internal structure could be considered a homogeneous, non-crystalline and molecularly dispersed polymer network. When beads with different charge densities were equilibrated with aqueous solutions of different ionic strengths and/or pH, the change in water uptake followed the trends expected for weak polyelectrolyte gels and the trends found for cellulose-rich fibers. When dried and subsequently immersed in water the beads also showed an irreversible loss of swelling depending on the charge and type of counter-ion which is commonly also found for cellulose-rich fibers. Taken all these results together it is clear that the model cellulose-based beads constitute an excellent tool for studying the fundamentals of swelling of cellulose rich plant fibers, aiding in the elucidation of the different molecular and supramolecular contributions to the swelling. Copyright © 2018 Elsevier Inc. All rights reserved.

Temporal and Spatial Scales of Sub-Continental Mantle Convection: Comparison of Modern and Geological Observations of Dynamic Support

NASA Astrophysics Data System (ADS)

Jones, S. M.; Lovell, B.; Crosby, A. G.

2011-12-01

The topographies of Africa and Antarctica form patterns of interlocking swells. The admittance between swell topography and free-air gravity indicates that these swells are dynamically supported by mantle convection, with swell diameters of 1850±450 km and full heights between 800 and 1800 m. The implication is that mantle convection not only supports swells surrounding hotspots but also influences topography across the entire surface areas of Africa and Antarctica. Topographic swells and associated gravity anomalies with diameters over 1000 km are observed on other continents and throughout the oceans. Numerical models support the idea that dynamically supported swell topography is a worldwide phenomenon. We investigate whether dynamically supported swells are also observed throughout the geological record, focussing on intensively studied Mesozoic- Cenozoic sedimentary rocks around Britain and Ireland. Since 200 Ma, this region was affected by three dynamically supported swells that peaked during the Middle Jurassic, Early Cretaceous and Eocene (c. 175, 146 and 56 Ma), each several thousand kilometres in diameter, and the region now lies on the edge of the modern swell centred on Iceland. The diameters and maximum heights of the Mesozoic British swells and the modern African and Antarctic swells are similar. The ancient British swells grew in 5--10 Myr and decayed over 20--30 Myr, suggesting vertical motion rates comparable to those estimated from geomorphological studies of Africa. Igneous production rate and swell height are not correlated in the modern and the geological records. Vertical motions of Britain and Ireland, a typical piece of continental lithosphere far from a destructive plate boundary, have been demonstrably affected by convective support for over half of the past 200 Ma period. Mantle convection should be considered as a common control on regional sea-level at time periods from 10s down to 1 Myr or less, and with vertical motion rates in the order 10s to 100s m/Myr.

Appraisal of jaw swellings in a Nigerian tertiary healthcare facility.

PubMed

Lasisi, Taye J; Adisa, Akinyele O; Olusanya, Adeola A

2013-02-01

The mandible and maxilla can be the site of myriads of lesions that may be categorized as neoplastic, cystic, reactive and infective or inflammatory. Literature reviewing jaw swellings in an amalgamated fashion are uncommon, probably because aetiologies for these swellings are varied. However, to appreciate their relative relationship, it is essential to evaluate the clinico-pathologic profile of jaw swellings. The aim of this appraisal is to describe the array of jaw swellings seen at our hospital from 1990 to 2011, to serve as a reference database. Biopsy records of all histologically diagnosed cases of jaw swellings seen at the department of Oral Pathology, University College Hospital between January 1990 and December 2011 were retrieved, coded and inputted into SPSS version 20. Data on prevalence, age, sex, site and histological diagnosis were analysed descriptively for each category of jaw swellings. All patients below 16 years were regarded as children. A total of 638 jaw swellings were recorded in the 22-year study period. The Non Odontogenic Tumours (NOT) were the commonest, accounting for 46.2% of all jaw swellings. Odontogenic Tumours (OT) formed 45% of all adult jaw swelling while it formed 25.2% in children and adolescents. Ameloblastoma was the commonest while the most common NOT was ossifying fibroma (OF). Chronic osteomyelitis of the jaws was about 6 times commoner in adult females than males and mostly involved the mandible. The most common malignant jaw swelling was Burkitts' lymphoma (BL) that was about 7 times more in children than adults. Osteogenic sarcoma was the most common malignancy in adults. Jaw swellings are extensively varied in types and pattern of occurrence. This study has categorized jaw swellings in a simple but comprehensive fashion to allow for easy referencing in local and international data acquisition and epidemiological comparison. Key words:Jaw swellings, odontogenic, Nigeria.

Water saturation of hydrothermal smectite-rich clay might have promoted slope instability prior to the 1998 debris avalanche at Casita volcano, Nicaragua

NASA Astrophysics Data System (ADS)

Delmelle, P.; Opfergelt, S.; Boivin, P.; Delvaux, B.

2006-12-01

In October 1998, a relatively small collapse (1 600 000 cubic meters) of a pre-existing scarp occurred on the southern flank of the dormant Casita volcano, Nicaragua. It resulted in a debris avalanche, which quickly transformed into a disastrous debris flow that destroyed two towns and killed more than 2500 people. The failure was shown to be triggered by an excess pore water pressure within highly fractured rocks, following prolonged seasonal rains and precipitations from Hurricane Mitch. This pressure was linked to the water saturation of a hydrothermally-altered clay bedrock impeding in-depth infiltration. Yet, the nature and amounts of the clay material involved in the slope failure were still unknown. Here we report on physical, chemical and mineralogical investigations aimed at quantifying the clay content, and identifying the layer silicates of the hydrothermally-altered clays uncovered by the 1998 debris avalanche. The fine clay material was exceptionally rich in smectite (up to 50 wt. percent), which swells upon wetting and shrinks during dry conditions (Opfergelt et al., 2006, Geophys. Res. Lett., 33 (15), L15305). The smectite belonged to the beidellite-montmorillonite series. The pervasive presence of water-saturated smectitic clay strongly reduced the permeability in depth, and also altered the rheological and mechanical properties of both the pre-failure rock mass and flow materials. The shrink-swell behavior progressively decreased the rock's shear strength, and gradually destabilized the overlying rock mass in the decades and centuries before the landslide, thereby contributing to slope instability. Prolonged intense rainfall led to the formation of incipient weak failure surfaces in the superficial rock mass. As provoked by water saturation, this process was likely favored by the rapid change of the mechanical properties of smectite-rich clays deposited in fracture, joint and gouge interfaces. We suggest that hazard assessments associated with unstable volcanic slopes, especially on volcanoes hosting a long-lived hydrothermal system, should include the potential long and short-term impacts of swelling clays.

Site-Specific Pre-Swelling-Directed Morphing Structures of Patterned Hydrogels.

PubMed

Wang, Zhi Jian; Hong, Wei; Wu, Zi Liang; Zheng, Qiang

2017-12-11

Morphing materials have promising applications in various fields, yet how to program the self-shaping process for specific configurations remains a challenge. Herein we show a versatile approach to control the buckling of individual domains and thus the outcome configurations of planar-patterned hydrogels. By photolithography, high-swelling disc gels were positioned in a non-swelling gel sheet; the swelling mismatch resulted in out-of-plain buckling of the disc gels. To locally control the buckling direction, masks with holes were used to guide site-specific swelling of the high-swelling gel under the holes, which built a transient through-thickness gradient and thus directed the buckling during the subsequent unmasked swelling process. Therefore, various configurations of an identical patterned hydrogel can be programmed by the pre-swelling step with different masks to encode the buckling directions of separate domains. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Compressive and swelling behavior of cuttlebone derived hydroxyapatite loaded PVA hydrogel implants for articular cartilage

NASA Astrophysics Data System (ADS)

Kumar, B. Y. Santosh; Kumar, G. C. Mohan; Isloor, Arun M.

2018-04-01

Developing a novel antibacterial, nontoxic and biocompatible hydrogel with superior physio mechanical properties is still becoming a challenge. Herein, we synthesize hydroxyapatite (HA) powder from cuttlefish bone and prepare a series of stiff, tough, high strength, biocompatible hydrogel reinforced with HA by integrating glutaraldehyde into PVA/HA. Powder was characterized by SEM and XRD. Compressive strength and swelling properties are studied and compare the results with the properties of healthy natural articular cartilage.

The development and structure of thick-walled, multicellular, aerial spores in Diheterospora chlamydosporia (=Verticillium chlamydosporium).

PubMed

Cambell, W P; Griffiths, D A

1975-07-01

The aerial, thick-walled spores in Diheterospara chlamydosporia arose as terminal swellings on erect hyphae. Repeated septation of the continuously swelling spore resulted in a multicellular structure. Immediately after the onset of septation secondary wall material was laid down between the two-layered primary wall and the plasmalemma. The presence of secondary wall material indicates that the multicellular spore is a dictyochlamydospore and not an aleuriospore. The relationship between chlamydospores and aleuriospores in other fungi is discussed.

Charge-regularized swelling kinetics of polyelectrolyte gels: Elasticity and diffusion

NASA Astrophysics Data System (ADS)

Sen, Swati; Kundagrami, Arindam

2017-11-01

We apply a recently developed method [S. Sen and A. Kundagrami, J. Chem. Phys. 143, 224904 (2015)], using a phenomenological expression of osmotic stress, as a function of polymer and charge densities, hydrophobicity, and network elasticity for the swelling of spherical polyelectrolyte (PE) gels with fixed and variable charges in a salt-free solvent. This expression of stress is used in the equation of motion of swelling kinetics of spherical PE gels to numerically calculate the spatial profiles for the polymer and free ion densities at different time steps and the time evolution of the size of the gel. We compare the profiles of the same variables obtained from the classical linear theory of elasticity and quantitatively estimate the bulk modulus of the PE gel. Further, we obtain an analytical expression of the elastic modulus from the linearized expression of stress (in the small deformation limit). We find that the estimated bulk modulus of the PE gel decreases with the increase of its effective charge for a fixed degree of deformation during swelling. Finally, we match the gel-front locations with the experimental data, taken from the measurements of charged reversible addition-fragmentation chain transfer gels to show an increase in gel-size with charge and also match the same for PNIPAM (uncharged) and imidazolium-based (charged) minigels, which specifically confirms the decrease of the gel modulus value with the increase of the charge. The agreement between experimental and theoretical results confirms general diffusive behaviour for swelling of PE gels with a decreasing bulk modulus with increasing degree of ionization (charge). The new formalism captures large deformations as well with a significant variation of charge content of the gel. It is found that PE gels with large deformation but same initial size swell faster with a higher charge.

Radiation response of alloy T91 at damage levels up to 1000 peak dpa

DOE PAGES

Gigax, J. G.; Chen, T.; Kim, Hyosim; ...

2016-10-04

Ferritic/martensitic alloys are required for advanced reactor components to survive 500–600 neutron-induced dpa. In this paper, ion-induced void swelling of ferritic/martensitic alloy T91 in the quenched and tempered condition has been studied using a defocused, non-rastered 3.5 MeV Fe-ion beam at 475 °C to produce damage levels up to 1000 peak displacements per atom (dpa). The high peak damage level of 1000 dpa is required to reach 500–600 dpa level due to injected interstitial suppression of void nucleation in the peak dpa region, requiring data extraction closer to the surface at lower dpa levels. At a relatively low peak damagemore » level of 250 dpa, voids began to develop, appearing first in the near-surface region. With increasing ion fluence, swelling was observed deeper in the specimen, but remained completely suppressed in the back half of the ion range, even at 1000 peak dpa. The local differences in dpa rate in the front half of the ion range induce an “internal temperature shift” that strongly influences the onset of swelling, with shorter transient regimes resulting from lower dpa rates, in agreement not only with observations in neutron irradiation studies but also in various ion irradiations. Swelling was accompanied by radiation-induced precipitation of Cu-rich and Si, Ni, Mn-rich phases were observed by atom probe tomography, indicating concurrent microchemical evolution was in progress. Finally, in comparison to other ferritic/martensitic alloys during ion irradiation, T91 exhibits good swelling resistance with a swelling incubation period of about 400 local dpa.« less

Application of laboratory reflectance spectroscopy to target and map expansive soils: example of the western Loiret, France

NASA Astrophysics Data System (ADS)

Hohmann, Audrey; Dufréchou, Grégory; Grandjean, Gilles; Bourguignon, Anne

2014-05-01

Swelling soils contain clay minerals that change volume with water content and cause extensive and expensive damage on infrastructures. Based on spatial distribution of infrastructure damages and existing geological maps, the Bureau de Recherches Géologiques et Minières (BRGM, i.e. the French Geological Survey) published in 2010 a 1:50 000 swelling hazard map of France, indexing the territory to low, moderate, or high swelling risk. This study aims to use SWIR (1100-2500 nm) reflectance spectra of soils acquired under laboratory controlled conditions to estimate the swelling potential of soils and improve the swelling risk map of France. 332 samples were collected at the W of Orléans (France) in various geological formations and swelling risk areas. Comparisons of swelling potential of soil samples and swelling risk areas of the map show several inconsistent associations that confirm the necessity to redraw the actual swelling risk map of France. New swelling risk maps of the sampling area were produce from soil samples using three interpolation methods. Maps produce using kriging and Natural neighbour interpolation methods did not permit to show discrete lithological units, introduced unsupported swelling risk zones, and did not appear useful to refine swelling risk map of France. Voronoi polygon was also used to produce map where swelling potential estimated from each samples were extrapolated to a polygon and all polygons were thus supported by field information. From methods tested here, Voronoi polygon appears thus the most adapted method to produce expansive soils maps. However, size of polygon is highly dependent of the samples spacing and samples may not be representative of the entire polygon. More samples are thus needed to provide reliable map at the scale of the sampling area. Soils were also sampled along two sections with a sampling interval of ca. 260 m and ca. 50 m. Sample interval of 50 m appears more adapted for mapping of smallest lithological units. The presence of several samples close to themselves indicating the same swelling potential is a good indication of the presence of a zone with constant swelling potential. Combination of Voronoi method and sampling interval of ca. 50 m appear adapted to produce local swelling potential maps in areas where doubt remain or where infrastructure damages attributed to expansive soils are knew.

Fish allergy causing angioedema and secondary angle-closure glaucoma.

PubMed

Calder, Donovan; Calder, Jennifer

2013-03-06

A 56-year-old woman with a history of primary angle-closure glaucoma presented with acute generalised swelling, and facial angioedema following a fish meal. She complained of nausea, vomiting, headache, pain in both eyes and acute loss of vision. Her visual acuity was reduced and intraocular pressures (IOP) were elevated. Gonioscopy revealed complete angle closure in the left eye and complete to partial closure in the right eye. Through existing peripheral iridotomies the anterior capsules were seen pressed up against the iris of both eyes. A diagnosis of angle-closure glaucoma was made, medications were started to reduce the elevated intraocular pressure and systemic antihistamine to counter the allergic reaction. She was hospitalised for further management. A follow-up at 2 years revealed her visual acuities and IOP had remained normal.

Protein vs electrolytes and all of the Starling forces.

PubMed

Peters, R M; Hargens, A R

1981-10-01

Hemodilution-induced reductions of the intravascular protein concentration in patients and experimental animals with intact capillaries do not lead to pulmonary edema, despite significant increases in the amount of extravascular water in the systemic interstitial space. The protective factors are a drop in the extravascular concentration of protein, a rise in interstitial tissue pressure, and an increase in lymph flow. If the capillary endothelium is damaged, protein leaks into the extravascular space, and protein infusion has a diminished effect on fluid exchange across the capillary. Whether capillaries are intact or injured, prevention of increases in capillary hydrostatic pressure is the most important factor in preventing pulmonary edema. Administration of hypertonic fluids may provide a useful method of limiting total fluid infusion and reducing cell swelling after blood loss.

Understanding the Alteration of Bentonite Backfill Using Coupled THMC Modeling for a Long Term Heater Test at the Grimsel Underground Research Lab

NASA Astrophysics Data System (ADS)

Birkholzer, J. T.; Zheng, L.; Xu, H.; Rutqvist, J.

2017-12-01

Compacted bentonite is commonly used as backfill material in emplacement tunnels of nuclear waste repositories because of its low permeability, high swelling pressure, and retardation capacity of radionuclide. To assess whether this backfill material can maintain these favorable features when undergoing heating from the waste package and hydration from the host rock, we need a thorough understanding of the thermal, hydrological, mechanical, and chemical evolution of bentonite under disposal conditions. Dedicated field tests integrated with THMC modeling provide an effective way to deepen such understanding. Here, we present coupled THMC models for an in situ heater test which was conducted at the Grimsel Test Site in Switzerland for 18 years. The comprehensive monitoring data obtained in the test provide a unique opportunity to evaluate bentonite integrity and test coupled THMC models. We developed a modeling strategy where conceptual model complexity is increased gradually by adding/testing processes such as Non-Darcian flow, enhanced vapor diffusion, thermal osmosis and different constitutive relationships for permeability/porosity changes due to swelling. The final THMC model explains well all the THM data and the concentration profiles of conservative chemical species. Over the course of modeling the in situ test, we learned that (1) including Non-Darcian flow into the model leads to a significant underestimation of hydration rate of bentonite, (2) chemical data provide an important additional piece of information for calibrating a THM model; (3) key processes needed to reproduce the data include vapor diffusion, as well as porosity and permeability changes due to swelling and thermal osmosis; (4) the concentration profiles of cations (calcium, potassium, magnesium and sodium) were largely shaped by transport processes despite their concentration levels being affected by mineral dissolution/precipitation and cation exchange. The concentration profiles of pH, bicarbonate and sulphate were largely determined by chemical reactions. These findings enable more reliable calculation of the time frame and condition of the early unsaturated phase in bentonite, the porosity and permeability after the bentonite becomes fully saturated, and how transport processes interact with reactions.

Evaluation of potential variables contributing to the development and duration of plantar lesions in a population of aquarium-maintained African penguins (Spheniscus demersus).

PubMed

Erlacher-Reid, Claire; Dunn, J Lawrence; Camp, Tracy; Macha, Laurie; Mazzaro, Lisa; Tuttle, Allison D

2012-01-01

Bumblefoot (pododermatitis), often described as the most significant environmental disease of captive penguins, is commonly due to excessive pressure or trauma on the plantar surface of the avian foot, resulting in inflammation or necrosis and causing severe swelling, abrasions, or cracks in the skin. Although not formally evaluated in penguins, contributing factors for bumblefoot are thought to be similar to those initiating the condition in raptors and poultry. These factors include substrate, body weight, and lack of exercise. The primary purpose of this retrospective study was to evaluate variables potentially contributing to the development and duration of plantar lesions in aquarium-maintained African penguins (Spheniscus demersus), including sex, weight, age, season, exhibit activity, and territory substrate. Results indicate that males develop significantly more plantar lesions than females. Penguins weighing between 3.51 and 4.0 kg develop plantar lesions significantly more often than penguins weighing between 2.5 and 3.5 kg, and because male African penguins ordinarily weigh significantly more than females, weight is likely a contributing factor in the development of lesions in males compared with females. Significantly more plantar lesions were observed in penguins standing for greater than 50% of their time on exhibit than swimming. Penguins occupying smooth concrete territories developed more plantar lesions compared with penguins occupying grate territories. Recommendations for minimizing bumblefoot in African penguins include training penguins for monthly foot examinations for early detection of plantar lesions predisposing for the disease, encouraging swimming activity, and replacing smooth surfaces on exhibit with surfaces providing variable degrees of pressure and texture on the feet. © 2011 Wiley Periodicals, Inc.

Wind, current and swell influences on the ice extent and flux in the Grand Banks-Labrador sea area as observed in the LIMEX '87 experiment

NASA Technical Reports Server (NTRS)

Argus, Susan Digby; Carsey, Frank; Holt, Benjamin

1988-01-01

This paper presents data collected by airborne and satellite instruments during the Labrador Ice Margin Experiment, that demonstrate the effects of oceanic and atmospheric processes on the ice conditions in the Grand Banks-Labrador sea area. Special consideration is given to the development of algorithms for extracting information from SAR data. It is shown that SAR data can be used to monitor ice extent, determine ice motion, locate shear zones, monitor the penetration of swell into the ice, estimate floe sizes, and establish the dimensions of the ice velocity zones. It is also shown that the complex interaction of the ice cover with winds, currents, swell, and coastlines is similar to the dynamics established for a number of sites in both polar regions.

Sorption equilibria of ethanol on cork.

PubMed

Lequin, Sonia; Chassagne, David; Karbowiak, Thomas; Bellat, Jean-Pierre

2013-06-05

We report here for the first time a thermodynamic study of gaseous ethanol sorption on raw cork powder and plate. Our study aims at a better understanding of the reactivity of this material when used as a stopper under enological conditions, thus in close contact with a hydroethanolic solution, wine. Sorption−desorption isotherms were accurately measured by thermogravimetry at 298 K in a large range of relative pressures. Sorption enthalpies were determined by calorimetry as a function of loading. Sorption−desorption isotherms exhibit a hysteresis loop probably due to the swelling of the material and the absorption of ethanol. Surprisingly, the sorption enthalpy of ethanol becomes lower than the liquefaction enthalpy as the filling increases. This result could be attributed to the swelling of the material, which would generate endothermic effects. Sorption of SO₂ on cork containing ethanol was also studied. When the ethanol content in cork is 2 wt %, the amount of SO₂ sorbed is divided by 2. Thus, ethanol does not enhance the sorption rate for SO₂ but, on the contrary, decreases the SO₂ sorption activity onto cork, probably because of competitive sorption mechanisms.

Compatibility of Halthane 88-3 urethane adhesive with the replacement cleaning solvent D-Limonene

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

LeMay, J.D.; Mendoza, B.

1991-08-01

D-Limonene, (R)1-methyl-4-isopropenyl-1-cyclohexene, has been identified as a leading replacement for chlorinated solvents traditionally used to clean electrical assemblies and critical components in some phases of weapons production. Unfortunately, d-limonene has a much lower vapor pressure than the chlorinated solvents if replaces (<2 torr at ambient). This makes its complete elimination from cleaned subassemblies potentially difficult, and gives rise to concerns about the compatibility of d-limonene with materials in the warhead. During the past year many WR polymers and adhesives have been surveyed for their compatibility with d-limonene. Preliminary test results obtained at Sandia (Albuquerque) and Allied-Signal (KCD) showed that Aluminum/Halthanemore » 88-3/Aluminum joints were destroyed during exposure to saturated d-limonene vapor. The cause of bond failure appeared to be d-limonene induced swelling of the Halthane polymer. This report describes recent work performed at LLNL to study the swelling behavior and bond strength degradation of Halthane 88-3 resulting from exposure to d-limonene vapor.« less

Helium in inert matrix dispersion fuels

NASA Astrophysics Data System (ADS)

van Veen, A.; Konings, R. J. M.; Fedorov, A. V.

2003-07-01

The behaviour of helium, an important decay product in the transmutation chains of actinides, in dispersion-type inert matrix fuels is discussed. A phenomenological description of its accumulation and release in CERCER and CERMET fuel is given. A summary of recent He-implantation studies with inert matrix metal oxides (ZrO 2, MgAl 2O 4, MgO and Al 2O 3) is presented. A general picture is that for high helium concentrations helium and vacancy defects form helium clusters which convert into over-pressurized bubbles. At elevated temperature helium is released from the bubbles. On some occasions thermal stable nano-cavities or nano-pores remain. On the basis of these results the consequences for helium induced swelling and helium storage in oxide matrices kept at 800-1000 °C will be discussed. In addition, results of He-implantation studies for metal matrices (W, Mo, Nb and V alloys) will be presented. Introduction of helium in metals at elevated temperatures leads to clustering of helium to bubbles. When operational temperatures are higher than 0.5 melting temperature, swelling and helium embrittlement might occur.

A biphasic model for bleeding in soft tissue

NASA Astrophysics Data System (ADS)

Chang, Yi-Jui; Chong, Kwitae; Eldredge, Jeff D.; Teran, Joseph; Benharash, Peyman; Dutson, Erik

2017-11-01

The modeling of blood passing through soft tissues in the body is important for medical applications. The current study aims to capture the effect of tissue swelling and the transport of blood under bleeding or hemorrhaging conditions. The soft tissue is considered as a non-static poro-hyperelastic material with liquid-filled voids. A biphasic formulation effectively, a generalization of Darcy's law-is utilized, treating the phases as occupying fractions of the same volume. The interaction between phases is captured through a Stokes-like friction force on their relative velocities and a pressure that penalizes deviations from volume fractions summing to unity. The soft tissue is modeled as a hyperelastic material with a typical J-shaped stress-strain curve, while blood is considered as a Newtonian fluid. The method of Smoothed Particle Hydrodynamics is used to discretize the conservation equations based on the ease of treating free surfaces in the liquid. Simulations of swelling under acute hemorrhage and of draining under gravity and compression will be demonstrated. Ongoing progress in modeling of organ tissues under injuries and surgical conditions will be discussed.

Modified developer increases line resolution in photosensitive resist

NASA Technical Reports Server (NTRS)

1965-01-01

Standard developer solution is mixed with dipropyl carbonate. This reduces swelling in the photosensitive resist and permits application of relatively thick films with minimal pinhole formation and increased line resolution.

Visual Impairment/Increased Intracranial Pressure (VIIP): Layman's Summary

NASA Technical Reports Server (NTRS)

Fogarty, Jennifer

2011-01-01

To date NASA has documented that seven long duration astronauts have experienced in-flight and post-flight changes in vision and eye anatomy including degraded distant vision, swelling of the back of the eye, and changes in the shape of the globe. We have also documented in a few of these astronauts post-flight, increases in the pressure of the fluid that surrounds the brain and spinal cord. This is referred to as increased intracranial pressure (ICP). The functional and anatomical changes have varied in severity and duration. In the post-flight time period, some individuals have experienced a return to a pre-flight level of visual function while others have experienced changes that remain significantly altered compared to pre-flight. In addition, the increased ICP also persists in the post-flight time period. Currently, the underlying cause or causes of these changes is/are unknown but the spaceflight community at NASA suspects that the shift of blood toward the head and the changes in physiology that accompany it, such as increased intracranial pressure, play a significant role.

Osmotic Pressure in Ionic Microgel Dispersions

NASA Astrophysics Data System (ADS)

Denton, Alan R.; Tang, Qiyun

2015-03-01

Microgels are microscopic gel particles, typically 10-1000 nm in size, that are swollen by a solvent. Hollow microgels (microcapsules) can encapsulate cargo, such as dye molecules or drugs, in their solvent-filled cavities. Their sensitive response to environmental conditions (e.g., temperature, pH) and influence on flow properties suit microgels to widespread applications in the chemical, pharmaceutical, food, and consumer care industries. When dispersed in water, polyelectrolyte gels become charged through dissociation of counterions. The electrostatic contribution to the osmotic pressure inside and outside of ionic microgels influences particle swelling and bulk materials properties, including thermodynamic, structural, optical, and rheological properties. Within the primitive and cell models of polyelectrolyte solutions, we derive an exact statistical mechanical formula for the contribution of mobile microions to the osmotic pressure within ionic microgels. Using Poisson-Boltzmann theory, we validate this result by explicitly calculating ion distributions across the surface of an ionic microgel and the electrostatic contribution to the osmotic pressure. Within a coarse-grained one-component model, we further chart the limits of the cell model for salty dispersions. This work was supported by the National Science Foundation under Grant No. DMR-1106331.

Non-traumatic trans-diaphragmatic intercostal hernia and cor pulmonale in a patient with poorly controlled obstructive sleep apnoea.

PubMed

Mehdi, Syed Basharath; Madi, Salem; Sudworth, Jordan

2016-10-28

Trans-diaphragmatic intercostal hernia is a rare entity. Patient with multiple medical comorbidities, including obstructive sleep apnoea, presents with shortness of breath, leg oedema and a bulging swelling through the right chest wall. CT shows partial herniation of the right lung and liver through intercostal space and an echocardiogram reveals right heart failure. He was treated initially with continuous positive airway pressure with poor response and subsequently treated with adaptive servo ventilation with much better symptomatic relief and treatment tolerance. 2016 BMJ Publishing Group Ltd.

Stratus 10: Tenth Setting of the Stratus Ocean Reference Station. Cruise RB-10-01 January 2 - January 30, 2010 Charleston, South Carolina - Valparaiso, Chile

DTIC Science & Technology

2010-05-01

data. Passed Florida Keys, turned south and crossed the Loop current. Swell from the west, choppy sea, cloudy then clearing in evening. Fire alarm...yr): 2 W/m2 (Colbo and Weller, 2009). Measurement is formed from one single snapshot each minute. 7) Barometric pressure Heise DXD ( Dresser ...have been crossing the ridge there because of a gap in the topography (Figures 5-9 and 5-13). A Seabeam survey was also done in anticipation of use

Creep and Sliding in Clay Slopes: Mutual Effects of Interlayer Swelling and Ice Jacking.

DTIC Science & Technology

1983-08-24

project, swelling and freezing, have been treated as well. The extent of swell heave of the montmorillonite clay under investigation depends on the...the amount of clay size particles: up to 70% and the amount of montmorillonite : up to 35%. 1.2. Grain Size Distribution Twelve hydrometer tests were...in physical conditions and exhibit swelling again upon subsequent wetting. Another important swelling parameter is the montmorillonite content, that

Dissecting anode swelling in commercial lithium-ion batteries

NASA Astrophysics Data System (ADS)

Zhang, Ningxin; Tang, Huaqiong

2012-11-01

An innovative method is applied to investigate anode swelling during electrochemical processes in commercial lithium-ion batteries. Cathode surface is partially covered with a piece of paste to block the transportation of lithium ion from active material during charging/discharging, and the corresponding part on the anode film shows no formation of Li-graphite compounds during different electrochemical processes, which is confirmed by XRD analysis. The increases of anode thickness within and outside lithiated zone are measured, and defined as electrochemical swelling and physical swelling respectively. The microscopic lattice expansion of graphite due to lithiation process correlates to mesoscopic electrochemical swelling synchronically, while physical swelling tends to decrease steadily with time. The relationship among the microscopic stress due to lithium-ion intercalation, the mesoscopic stress resulting in anode swelling, and the macroscopic rippling of pouch cell after a large number of cycle test, is analyzed and correlated in terms of stress evolution across different scales, and suggestions for solving anode swelling are provided.

Effect of synthesis parameters on polymethacrylic acid xerogel structures and equilibrium swelling

NASA Astrophysics Data System (ADS)

Panić, V.; Jovanović, J.; Adnadjević, B.; Velicković, S.

2009-09-01

Hydrogels based on crosslinked polymethacrylic acid were synthesized via free-radical polymerization in aqueous solution, using N,N'-methylene bisacrylamide as a crosslinking agent and 2,2'-azobis-[2-(2-imidazolin-2-yl)propane] dihydrochloride as an initiator. The influence of the reaction parameters (the neutralization degree of methacrylic acid and the initial monomer concentration) on the equilibrium swelling degree, the swelling kinetic parameters and the basic structural properties of xerogels was investigated. The change of synthesis parameters leads to the change of the basic structural parameters of xerogel, as well as the equilibrium swelling degree and the initial swelling rate of the hydrogels. It is found that there are power form relationships between the equilibrium swelling degree, the initial swelling rate and the structural xerogel’s properties and the change of the neutralization degree of monomer, i.e. the monomer concentration. The examined correlations proved that the crosslinking density is the crucial parameter which determines all the other investigated structural and swelling parameters.

Dimensional stability and anisotropy of SiC and SiC-based composites in transition swelling regime

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

Katoh, Yutai; Koyanagi, Takaaki; McDuffee, Joel L.

Swelling, or volumetric expansion, is an inevitable consequence of the atomic displacement damage in crystalline silicon carbide (SiC) caused by energetic neutron irradiation. Because of its steep temperature and dose dependence, understanding swelling is essential for designing SiC-based components for nuclear applications. Here in this study, swelling behaviors of monolithic CVD SiC and nuclear grade SiC fiber – SiC matrix (SiC/SiC) composites were accurately determined, supported by the irradiation temperature determination for individual samples, following neutron irradiation within the lower transition swelling temperature regime. Slightly anisotropic swelling behaviors were found for the SiC/SiC samples and attributed primarily to the combinedmore » effects of the pre-existing microcracking, fiber architecture, and specimen dimension. A semi-empirical model of SiC swelling was calibrated and presented. Finally, implications of the refined model to selected swelling-related issues for SiC-based nuclar reactor components are discussed.« less

Dimensional stability and anisotropy of SiC and SiC-based composites in transition swelling regime

DOE PAGES

Katoh, Yutai; Koyanagi, Takaaki; McDuffee, Joel L.; ...

2017-12-08

Swelling, or volumetric expansion, is an inevitable consequence of the atomic displacement damage in crystalline silicon carbide (SiC) caused by energetic neutron irradiation. Because of its steep temperature and dose dependence, understanding swelling is essential for designing SiC-based components for nuclear applications. Here in this study, swelling behaviors of monolithic CVD SiC and nuclear grade SiC fiber – SiC matrix (SiC/SiC) composites were accurately determined, supported by the irradiation temperature determination for individual samples, following neutron irradiation within the lower transition swelling temperature regime. Slightly anisotropic swelling behaviors were found for the SiC/SiC samples and attributed primarily to the combinedmore » effects of the pre-existing microcracking, fiber architecture, and specimen dimension. A semi-empirical model of SiC swelling was calibrated and presented. Finally, implications of the refined model to selected swelling-related issues for SiC-based nuclar reactor components are discussed.« less

Musculoskeletal Modeling of the Lumbar Spine to Explore Functional Interactions between Back Muscle Loads and Intervertebral Disk Multiphysics

PubMed Central

Toumanidou, Themis; Noailly, Jérôme

2015-01-01

During daily activities, complex biomechanical interactions influence the biophysical regulation of intervertebral disks (IVDs), and transfers of mechanical loads are largely controlled by the stabilizing action of spine muscles. Muscle and other internal forces cannot be easily measured directly in the lumbar spine. Hence, biomechanical models are important tools for the evaluation of the loads in those tissues involved in low-back disorders. Muscle force estimations in most musculoskeletal models mainly rely, however, on inverse calculations and static optimizations that limit the predictive power of the numerical calculations. In order to contribute to the development of predictive systems, we coupled a predictive muscle model with the passive resistance of the spine tissues, in a L3–S1 musculoskeletal finite element model with osmo-poromechanical IVD descriptions. The model included 46 fascicles of the major back muscles that act on the lower spine. The muscle model interacted with activity-related loads imposed to the osteoligamentous structure, as standing position and night rest were simulated through distributed upper body mass and free IVD swelling, respectively. Calculations led to intradiscal pressure values within ranges of values measured in vivo. Disk swelling led to muscle activation and muscle force distributions that seemed particularly appropriate to counterbalance the anterior body mass effect in standing. Our simulations pointed out a likely existence of a functional balance between stretch-induced muscle activation and IVD multiphysics toward improved mechanical stability of the lumbar spine understanding. This balance suggests that proper night rest contributes to mechanically strengthen the spine during day activity. PMID:26301218

Multiscale climate emulator of multimodal wave spectra: MUSCLE-spectra

NASA Astrophysics Data System (ADS)

Rueda, Ana; Hegermiller, Christie A.; Antolinez, Jose A. A.; Camus, Paula; Vitousek, Sean; Ruggiero, Peter; Barnard, Patrick L.; Erikson, Li H.; Tomás, Antonio; Mendez, Fernando J.

2017-02-01

Characterization of multimodal directional wave spectra is important for many offshore and coastal applications, such as marine forecasting, coastal hazard assessment, and design of offshore wave energy farms and coastal structures. However, the multivariate and multiscale nature of wave climate variability makes this complex problem tractable using computationally expensive numerical models. So far, the skill of statistical-downscaling model-based parametric (unimodal) wave conditions is limited in large ocean basins such as the Pacific. The recent availability of long-term directional spectral data from buoys and wave hindcast models allows for development of stochastic models that include multimodal sea-state parameters. This work introduces a statistical downscaling framework based on weather types to predict multimodal wave spectra (e.g., significant wave height, mean wave period, and mean wave direction from different storm systems, including sea and swells) from large-scale atmospheric pressure fields. For each weather type, variables of interest are modeled using the categorical distribution for the sea-state type, the Generalized Extreme Value (GEV) distribution for wave height and wave period, a multivariate Gaussian copula for the interdependence between variables, and a Markov chain model for the chronology of daily weather types. We apply the model to the southern California coast, where local seas and swells from both the Northern and Southern Hemispheres contribute to the multimodal wave spectrum. This work allows attribution of particular extreme multimodal wave events to specific atmospheric conditions, expanding knowledge of time-dependent, climate-driven offshore and coastal sea-state conditions that have a significant influence on local nearshore processes, coastal morphology, and flood hazards.

Multiscale Climate Emulator of Multimodal Wave Spectra: MUSCLE-spectra

NASA Astrophysics Data System (ADS)

Rueda, A.; Hegermiller, C.; Alvarez Antolinez, J. A.; Camus, P.; Vitousek, S.; Ruggiero, P.; Barnard, P.; Erikson, L. H.; Tomas, A.; Mendez, F. J.

2016-12-01

Characterization of multimodal directional wave spectra is important for many offshore and coastal applications, such as marine forecasting, coastal hazard assessment, and design of offshore wave energy farms and coastal structures. However, the multivariate and multiscale nature of wave climate variability makes this problem complex yet tractable using computationally-expensive numerical models. So far, the skill of statistical-downscaling models based parametric (unimodal) wave conditions is limited in large ocean basins such as the Pacific. The recent availability of long-term directional spectral data from buoys and wave hindcast models allows for development of stochastic models that include multimodal sea-state parameters. This work introduces a statistical-downscaling framework based on weather types to predict multimodal wave spectra (e.g., significant wave height, mean wave period, and mean wave direction from different storm systems, including sea and swells) from large-scale atmospheric pressure fields. For each weather type, variables of interest are modeled using the categorical distribution for the sea-state type, the Generalized Extreme Value (GEV) distribution for wave height and wave period, a multivariate Gaussian copula for the interdependence between variables, and a Markov chain model for the chronology of daily weather types. We apply the model to the Southern California coast, where local seas and swells from both the Northern and Southern Hemispheres contribute to the multimodal wave spectrum. This work allows attribution of particular extreme multimodal wave events to specific atmospheric conditions, expanding knowledge of time-dependent, climate-driven offshore and coastal sea-state conditions that have a significant influence on local nearshore processes, coastal morphology, and flood hazards.

Recommendations for the management of cerebral and cerebellar infarction with swelling: a statement for healthcare professionals from the American Heart Association/American Stroke Association.

PubMed

Wijdicks, Eelco F M; Sheth, Kevin N; Carter, Bob S; Greer, David M; Kasner, Scott E; Kimberly, W Taylor; Schwab, Stefan; Smith, Eric E; Tamargo, Rafael J; Wintermark, Max

2014-04-01

There are uncertainties surrounding the optimal management of patients with brain swelling after an ischemic stroke. Guidelines are needed on how to manage this major complication, how to provide the best comprehensive neurological and medical care, and how to best inform families facing complex decisions on surgical intervention in deteriorating patients. This scientific statement addresses the early approach to the patient with a swollen ischemic stroke in a cerebral or cerebellar hemisphere. The writing group used systematic literature reviews, references to published clinical and epidemiology studies, morbidity and mortality reports, clinical and public health guidelines, authoritative statements, personal files, and expert opinion to summarize existing evidence and to indicate gaps in current knowledge. The panel reviewed the most relevant articles on adults through computerized searches of the medical literature using MEDLINE, EMBASE, and Web of Science through March 2013. The evidence is organized within the context of the American Heart Association framework and is classified according to the joint American Heart Association/American College of Cardiology Foundation and supplementary American Heart Association Stroke Council methods of classifying the level of certainty and the class and level of evidence. The document underwent extensive American Heart Association internal peer review. Clinical criteria are available for hemispheric (involving the entire middle cerebral artery territory or more) and cerebellar (involving the posterior inferior cerebellar artery or superior cerebellar artery) swelling caused by ischemic infarction. Clinical signs that signify deterioration in swollen supratentorial hemispheric ischemic stroke include new or further impairment of consciousness, cerebral ptosis, and changes in pupillary size. In swollen cerebellar infarction, a decrease in level of consciousness occurs as a result of brainstem compression and therefore may include early loss of corneal reflexes and the development of miosis. Standardized definitions should be established to facilitate multicenter and population-based studies of incidence, prevalence, risk factors, and outcomes. Identification of patients at high risk for brain swelling should include clinical and neuroimaging data. If a full resuscitative status is warranted in a patient with a large territorial stroke, admission to a unit with neurological monitoring capabilities is needed. These patients are best admitted to intensive care or stroke units attended by skilled and experienced physicians such as neurointensivists or vascular neurologists. Complex medical care includes airway management and mechanical ventilation, blood pressure control, fluid management, and glucose and temperature control. In swollen supratentorial hemispheric ischemic stroke, routine intracranial pressure monitoring or cerebrospinal fluid diversion is not indicated, but decompressive craniectomy with dural expansion should be considered in patients who continue to deteriorate neurologically. There is uncertainty about the efficacy of decompressive craniectomy in patients ≥60 years of age. In swollen cerebellar stroke, suboccipital craniectomy with dural expansion should be performed in patients who deteriorate neurologically. Ventriculostomy to relieve obstructive hydrocephalus after a cerebellar infarct should be accompanied by decompressive suboccipital craniectomy to avoid deterioration from upward cerebellar displacement. In swollen hemispheric supratentorial infarcts, outcome can be satisfactory, but one should anticipate that one third of patients will be severely disabled and fully dependent on care even after decompressive craniectomy. Surgery after a cerebellar infarct leads to acceptable functional outcome in most patients. Swollen cerebral and cerebellar infarcts are critical conditions that warrant immediate, specialized neurointensive care and often neurosurgical intervention. Decompressive craniectomy is a necessary option in many patients. Selected patients may benefit greatly from such an approach, and although disabled, they may be functionally independent.

Protein kinase C enhances the swelling-induced chloride current in human atrial myocytes.

PubMed

Li, Ye-Tao; Du, Xin-Ling

2016-06-01

Swelling-activated chloride currents (ICl.swell) are thought to play a role in several physiologic and pathophysiologic processes and thus represent a target for therapeutic approaches. However, the mechanism of ICl.swell regulation remains unclear. In this study, we used the whole-cell patch-clamp technique to examine the role of protein kinase C (PKC) in the regulation of ICl.swell in human atrial myocytes. Atrial myocytes were isolated from the right atrial appendages of patients undergoing coronary artery bypass and enzymatically dissociated. ICl.swell was evoked in hypotonic solution and recorded using the whole-cell patch-clamp technique. The PKC agonist phorbol dibutyrate (PDBu) enhanced ICl.swell in a concentration-dependent manner, which was reversed in isotonic solution and by a chloride current inhibitor, 9-anthracenecarboxylicacid. Furthermore, the PKC inhibitor bis-indolylmaleimide attenuated the effect and 4α-PDBu, an inactive PDBu analog, had no effect on ICl.swell. These results, obtained using the whole-cell patch-clamp technique, demonstrate the ability of PKC to activate ICl,swell in human atrial myocytes. This observation was consistent with a previous study using a single-channel patch-clamp technique, but differed from some findings in other species.

Brain anti-cytoxic edema agents.

PubMed

Kimelberg, H K; Barron, K D; Bourke, R S; Nelson, L R; Cragoe, E J

1990-01-01

The work described in this chapter has indicated that improved outcome from an experimental head injury model can be achieved by drugs which are non-diuretic derivatives of loop diuretics, namely indanyl and fluorenyl compounds which are derivatives of ethacrynic acid. These drugs were originally identified by us on the basis of their efficacy in inhibiting [K+]-stimulated, HCO3(-)-dependent swelling of brain cerebrocortical slices. Swelling of glial cells (astrocytes) has long been known to be associated with such slice swelling and astrocyte swelling is a major locus of cytotoxic or cellular brain edema. Qualitative and quantitative electron microscope studies have shown that L644,711, a particularly effective member of the fluorenyl class of drugs, inhibits astrocytic swelling associated with an experimental animal head injury model. We have suggested that astrocytic swelling in pathological states may be partly due to activation of Cl-/HCO3- and Na+/H+ exchange systems driven by increased astrocytic intracellular hydration of CO2, and recent work has indeed shown that the ability of the indanyl and fluorenyl drugs to inhibit brain slice swelling and protect against head injury correlates closely with their ability to inhibit Cl-/HCO3- exchange. All these data suggest that astrocytic swelling, which seems to precede neuronal degeneration and breakdown of the blood-brain barrier, is deleterious and that prevention of such swelling can lead to effective therapy. We have used primary astrocytic cultures to explore reasons why astrocytic swelling could be harmful. Exposing such astrocytes to hypotonic medium causes rapid swelling with a slower return to normal volume in the continued presence of hypotonic medium, a process known as regulatory volume decrease or RVD. Such RVD is associated with marked release of several amino acids, including L-glutamate. L644,711 and other Cl-/HCO3- transport inhibitors such as SITS and furosemide, but not the selective Na+ + K+ + 2Cl- co-transport inhibitor bumetanide, inhibit such swelling-induced release of L-glutamate. Thus, L644,711 and other drugs may be effective in promoting recovery from head injury and other pathological states in which astrocytic swelling occurs either by initially preventing the swelling or inhibiting the release of excitotoxic excitatory amino acids if swelling does occur, perhaps depending at what time the drug is given.

Interferon-alpha/beta deficiency greatly exacerbates arthritogenic disease in mice infected with wild-type chikungunya virus but not with the cell culture-adapted live-attenuated 181/25 vaccine candidate

PubMed Central

Gardner, Christina L.; Burke, Crystal W.; Higgs, Stephen T.; Klimstra, William B.; Ryman, Kate D.

2012-01-01

In humans, chikungunya virus (CHIKV) infection causes fever, rash, and acute and persisting polyarthalgia/arthritis associated with joint swelling. We report a new CHIKV disease model in adult mice that distinguishes the wild-type CHIKV-LR strain from the live-attenuated vaccine strain (CHIKV-181/25). Although eight-week old normal mice inoculated in the hind footpad developed no hind limb swelling with either virus, CHIKV-LR replicated in musculoskeletal tissues and caused detectable inflammation. In mice deficient in STAT1-dependent interferon (IFN) responses, CHIKV-LR caused significant swelling of the inoculated and contralateral limbs and dramatic inflammatory lesions, while CHIKV-181/25 vaccine and another arthritogenic alphavirus, Sindbis, failed to induce swelling. IFN responses suppressed CHIKV-LR and CHIKV-181/25 replication equally in dendritic cells in vitro whereas macrophages were refractory to infection independently of STAT1-mediated IFN responses. Glycosaminoglycan (GAG) binding may be a CHIKV vaccine attenuation mechanism as CHIKV-LR infectivity was not dependent upon GAG, while CHIKV-181/25 was highly dependent. PMID:22305131

The engineering significance of shrinkage and swelling soils in blast damage investigations

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

Vitton, S.J.; Harris, W.W.

1996-12-01

In the US each year it has been estimated that expansive soils cause approximately $9.0 billion in damage to buildings, roads, airports, and other facilities. This figure alone exceeds the damage estimate for earthquakes, floods, tornadoes, and hurricanes combined. Unfortunately, some cases of expansive soil damage (swelling) are blamed on rock blasting operations if the blasting operations are located within the immediate area. While simple tests, such as the Atterberg limits test, can characterize a soil as expansive, it does not necessarily answer the question whether the foundation soils are causing distresses to a structure. In particular, it appears thatmore » once a soil has been labeled as nonexpansive it is no longer considered as a problem soil, in which case blast vibrations become the prime suspect. It should be emphasized, however, that even non-plastic soils, those soils with low to nonexistent plastic indexes, can exhibit significant shrinkage characteristics that can result in significant damage to structures. While expansive soil is a function of the mineralogy of the soil particles, i.e., swelling clay minerals, shrinkage is caused by the loss of moisture from soil as capillary pressures exceed the cohesion or tensile strength and is therefore a function of the soils particle size and its pore size distribution. This is a significant problem for all fine grained soils regardless of the soil`s mineralogy. It`s particularly important for regions of the US that typically have a positive water balance but experience significant drought periods when soil moisture is lost.« less

An atomistic model for cross-linked HNBR elastomers used in seals

NASA Astrophysics Data System (ADS)

Molinari, Nicola; Sutton, Adrian; Stevens, John; Mostofi, Arash

2015-03-01

Hydrogenated nitrile butadiene rubber (HNBR) is one of the most common elastomeric materials used for seals in the oil and gas industry. These seals sometimes suffer ``explosive decompression,'' a costly problem in which gases permeate a seal at the elevated temperatures and pressures pertaining in oil and gas wells, leading to rupture when the seal is brought back to the surface. The experimental evidence that HNBR and its unsaturated parent NBR have markedly different swelling properties suggests that cross-linking may occur during hydrogenation of NBR to produce HNBR. We have developed a code compatible with the LAMMPS molecular dynamics package to generate fully atomistic HNBR configurations by hydrogenating initial NBR structures. This can be done with any desired degree of cross-linking. The code uses a model of atomic interactions based on the OPLS-AA force-field. We present calculations of the dependence of a number of bulk properties on the degree of cross-linking. Using our atomistic representations of HNBR and NBR, we hope to develop a better molecular understanding of the mechanisms that result in explosive decompression.

Characterization of poly(vinyl acetate) based floating matrix tablets.

PubMed

Strübing, Sandra; Metz, Hendrik; Mäder, Karsten

2008-03-03

Floating Kollidon SR matrix tablets containing Propranolol HCl were developed and characterized with respect to drug release characteristics and floating strength. Kollidon SR was able to delay Propranolol HCl release efficiently. Drug release kinetics was evaluated using the Korsmeyer-Peppas model and found to be governed by Fickian diffusion. Tablet floating started immediately and continued for 24 h. It was possible to monitor the floating strength of the matrix devices using a simple experimental setup. Floating strength was related to Kollidon SR level with improved floating characteristics for samples with a high polymer/drug ratio. Swelling characteristics of the tablets were analyzed by applying the equation according to Therien-Aubin et al. The influence of the polymer content on swelling characteristics was found to be only marginal. Furthermore, the new method of benchtop MRI was introduced to study the water diffusion and swelling behaviour non-invasively and continuously.

Mechanics of the fast-start: muscle function and the role of intramuscular pressure in the escape behavior of amia calva and polypterus palmas

PubMed

Westneat; Hale; Mchenry; Long

1998-11-01

The fast-start escape response is a rapid, powerful body motion used to generate high accelerations of the body in virtually all fishes. Although the neurobiology and behavior of the fast-start are often studied, the patterns of muscle activity and muscle force production during escape are less well understood. We studied the fast-starts of two basal actinopterygian fishes (Amia calva and Polypterus palmas) to investigate the functional morphology of the fast-start and the role of intramuscular pressure (IMP) in escape behavior. Our goals were to determine whether IMP increases during fast starts, to look for associations between muscle activity and elevated IMP, and to determine the functional role of IMP in the mechanics of the escape response. We simultaneously recorded the kinematics, muscle activity patterns and IMP of four A. calva and three P. palmas during the escape response. Both species generated high IMPs of up to 90 kPa (nearly 1 atmosphere) above ambient during the fast-start. The two species showed similar pressure magnitudes but had significantly different motor patterns and escape performance. Stage 1 of the fast-start was generated by simultaneous contraction of locomotor muscle on both sides of the body, although electromyogram amplitudes on the contralateral (convex) side of the fish were significantly lower than on the ipsilateral (concave) side. Simultaneous recordings of IMP, escape motion and muscle activity suggest that pressure change is caused by the contraction and radial swelling of cone-shaped myomeres. We develop a model of IMP production that incorporates myomere geometry, the concept of constant-volume muscular hydrostats, the relationship between fiber angle and muscle force, and the forces that muscle fibers produce. The timing profile of pressure change, behavior and muscle action indicates that elevated muscle pressure is a mechanism of stiffening the body and functions in force transmission during the escape response.

The Time Course of Knee Swelling Post Total Knee Arthroplasty and Its Associations with Quadriceps Strength and Gait Speed.

PubMed

Pua, Yong-Hao

2015-07-01

This study examines the time course of knee swelling post total knee arthroplasty (TKA) and its associations with quadriceps strength and gait speed. Eighty-five patients with unilateral TKA participated. Preoperatively and on post-operative days (PODs) 1, 4, 14, and 90, knee swelling was measured using bioimpedance spectrometry. Preoperatively and on PODs 14 and 90, quadriceps strength was measured using isokinetic dynamometry while fast gait speed was measured using the timed 10-meter walk. On POD1, knee swelling increased ~35% from preoperative levels after which, knee swelling reduced but remained at ~11% above preoperative levels on POD90. In longitudinal, multivariable analyses, knee swelling was associated with quadriceps weakness (P<0.01) and slower gait speed (P=0.03). Interventions to reduce post-TKA knee swelling may be indicated to improve quadriceps strength and gait speed. Copyright © 2015 Elsevier Inc. All rights reserved.

Influence of Chitosan Swelling Behaviour on Controlled Release of Tenofovir from Mucoadhesive Vaginal Systems for Prevention of Sexual Transmission of HIV

PubMed Central

Notario-Pérez, Fernando; Martín-Illana, Araceli; Cazorla-Luna, Raúl; Ruiz-Caro, Roberto; Bedoya, Luis-Miguel; Tamayo, Aitana; Rubio, Juan; Veiga, María-Dolores

2017-01-01

The main challenges facing efforts to prevent the transmission of human immunodeficiency virus (HIV) are the lack of access to sexual education services and sexual violence against young women and girls. Vaginal formulations for the prevention of sexually transmitted infections are currently gaining importance in drug development. Vaginal mucoadhesive tablets can be developed by including natural polymers that have good binding capacity with mucosal tissues, such as chitosan or guar gum, semisynthetic polymers such as hydroxypropylmethyl cellulose, or synthetic polymers such as Eudragit® RS. This paper assesses the potential of chitosan for the development of sustained-release vaginal tablets of Tenofovir and compares it with different polymers. The parameters assessed were the permanence time of the bioadhesion—determined ex vivo using bovine vaginal mucosa as substrate—the drug release profiles from the formulation to the medium (simulated vaginal fluid), and swelling profiles in the same medium. Chitosan can be said to allow the manufacture of tablets that remain adhered to the vaginal mucosa and release the drug in a sustained way, with low toxicity and moderate swelling that ensures the comfort of the patient and may be useful for the prevention of sexual transmission of HIV. PMID:28230790

Influence of Chitosan Swelling Behaviour on Controlled Release of Tenofovir from Mucoadhesive Vaginal Systems for Prevention of Sexual Transmission of HIV.

PubMed

Notario-Pérez, Fernando; Martín-Illana, Araceli; Cazorla-Luna, Raúl; Ruiz-Caro, Roberto; Bedoya, Luis-Miguel; Tamayo, Aitana; Rubio, Juan; Veiga, María-Dolores

2017-02-21

The main challenges facing efforts to prevent the transmission of human immunodeficiency virus (HIV) are the lack of access to sexual education services and sexual violence against young women and girls. Vaginal formulations for the prevention of sexually transmitted infections are currently gaining importance in drug development. Vaginal mucoadhesive tablets can be developed by including natural polymers that have good binding capacity with mucosal tissues, such as chitosan or guar gum, semisynthetic polymers such as hydroxypropylmethyl cellulose, or synthetic polymers such as Eudragit ® RS. This paper assesses the potential of chitosan for the development of sustained-release vaginal tablets of Tenofovir and compares it with different polymers. The parameters assessed were the permanence time of the bioadhesion-determined ex vivo using bovine vaginal mucosa as substrate-the drug release profiles from the formulation to the medium (simulated vaginal fluid), and swelling profiles in the same medium. Chitosan can be said to allow the manufacture of tablets that remain adhered to the vaginal mucosa and release the drug in a sustained way, with low toxicity and moderate swelling that ensures the comfort of the patient and may be useful for the prevention of sexual transmission of HIV.

Molecular Dynamics Study of Crystalline Swelling of Montmorillonite as Affected by Interlayer Cation Hydration

NASA Astrophysics Data System (ADS)

Li, Hongliang; Song, Shaoxian; Dong, Xianshu; Min, Fanfei; Zhao, Yunliang; Peng, Chenliang; Nahmad, Yuri

2018-04-01

Swelling of montmorillonite (Mt) is an important factor for many industrial applications. In this study, crystalline swelling of alkali-metal- and alkaline-earth-metal-Mt has been studied through energy optimization and molecular dynamics simulations using the clay force field by Materials Studio 8.0. The delamination and exfoliation of Mt are primarily realized by crystalline swelling caused by the enhanced interlayer cation hydration. The initial position of the interlayer cations and water molecules is the dominated factor for the accuracy of the Mt simulations. Crystalline swelling can be carried out in alkali-metal-Mt and Mg-Mt but with difficulty in Ca-Mt, Sr-Mt and Ba-Mt. The crystalline swelling capacity values are in the order Na-Mt > K-Mt > Cs-Mt > Mg-Mt. This order of crystalline swelling of Mt in the same group can be attributed to the differences between the interlayer cation hydration strengths. In addition, the differences in the crystalline swelling between the alkali-metal-Mt and alkaline-earth-metal-Mt can be primarily attributed to the valence of the interlayer cations.

Influence of injected interstitials on the void swelling in two structural variants of 304L stainless steel induced by self-ion irradiation at 500 °C

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

Sun, C.; Garner, F. A.; Shao, L.

The two variants of AISI 304L stainless steel (SS) with different grain size distributions were ion irradiated at 500 °C to a peak dose of ~60 dpa. In the coarse-grained annealed variant, a peak swelling of ~12% was observed closer to the specimen surface rather than at the depth of peak displacement damage. The forward shift in depth between peak swelling and peak dose is proposed to be a consequence of suppression of void nucleation by injected interstitials. The swelling behavior in the front portion of the ion range mirrors that of neutron-induced swelling in this steel, exhibiting significant curvaturemore » with increasing dose as the swelling rate approaches the terminal swelling rate of 1%/dpa. Furthermore, an ultrafine grain variant of this steel produced by severely plastic deformation exhibits a similar suppression of void nucleation in the injected interstitial region, but also shows a significantly extended transient regime, not reaching the terminal swelling rate by 60 dpa.« less

Influence of injected interstitials on the void swelling in two structural variants of 304L stainless steel induced by self-ion irradiation at 500 °C

DOE PAGES

Sun, C.; Garner, F. A.; Shao, L.; ...

2017-03-28

The two variants of AISI 304L stainless steel (SS) with different grain size distributions were ion irradiated at 500 °C to a peak dose of ~60 dpa. In the coarse-grained annealed variant, a peak swelling of ~12% was observed closer to the specimen surface rather than at the depth of peak displacement damage. The forward shift in depth between peak swelling and peak dose is proposed to be a consequence of suppression of void nucleation by injected interstitials. The swelling behavior in the front portion of the ion range mirrors that of neutron-induced swelling in this steel, exhibiting significant curvaturemore » with increasing dose as the swelling rate approaches the terminal swelling rate of 1%/dpa. Furthermore, an ultrafine grain variant of this steel produced by severely plastic deformation exhibits a similar suppression of void nucleation in the injected interstitial region, but also shows a significantly extended transient regime, not reaching the terminal swelling rate by 60 dpa.« less

Molecular simulation of the swelling of polyelectrolyte gels by monovalent and divalent counterions

PubMed Central

Yin, De-Wei; Horkay, Ferenc; Douglas, Jack F.; de Pablo, Juan J.

2008-01-01

Permanently crosslinked polyelectrolyte gels are known to undergo discontinuous first-order volume phase transitions, the onset of which may be caused by a number of factors. In this study we examine the volumetric properties of such polyelectrolyte gels in relation to the progressive substitution of monovalent counterions by divalent counterions as the gels are equilibrated in solvents of different dielectric qualities. We compare the results of coarse-grained molecular dynamics simulations of polyelectrolyte gels with previous experimental measurements by others on polyacrylate gels. The simulations show that under equilibrium conditions there is an approximate cancellation between the electrostatic contribution and the counterion excluded-volume contribution to the osmotic pressure in the gel-solvent system; these two contributions to the osmotic pressure have, respectively, energetic and entropic origins. The finding of such a cancellation between the two contributions to the osmotic pressure of the gel-solvent system is consistent with experimental observations that the swelling behavior of polyelectrolyte gels can be described by equations of state for neutral gels. Based on these results, we show and explain that a modified form of the Flory–Huggins model for nonionic polymer solutions, which accounts for neither electrostatic effects nor counterion excluded-volume effects, fits both experimental and simulated data for polyelectrolyte gels. The Flory–Huggins interaction parameters obtained from regression to the simulation data are characteristic of ideal polymer solutions, whereas the experimentally obtained interaction parameters, particularly that associated with the third virial coefficient, exhibit a significant departure from ideality, leading us to conclude that further enhancements to the simulation model, such as the inclusion of excess salt, the allowance for size asymmetric electrolytes, or the use of a distance-dependent solvent dielectricity model, may be required. Molecular simulations also reveal that the condensation of divalent counterions onto the polyelectrolyte network backbone occurs preferentially over that of monovalent counterions. PMID:19045224

Molecular simulation of the swelling of polyelectrolyte gels by monovalent and divalent counterions.

PubMed

Yin, De-Wei; Horkay, Ferenc; Douglas, Jack F; de Pablo, Juan J

2008-10-21

Permanently crosslinked polyelectrolyte gels are known to undergo discontinuous first-order volume phase transitions, the onset of which may be caused by a number of factors. In this study we examine the volumetric properties of such polyelectrolyte gels in relation to the progressive substitution of monovalent counterions by divalent counterions as the gels are equilibrated in solvents of different dielectric qualities. We compare the results of coarse-grained molecular dynamics simulations of polyelectrolyte gels with previous experimental measurements by others on polyacrylate gels. The simulations show that under equilibrium conditions there is an approximate cancellation between the electrostatic contribution and the counterion excluded-volume contribution to the osmotic pressure in the gel-solvent system; these two contributions to the osmotic pressure have, respectively, energetic and entropic origins. The finding of such a cancellation between the two contributions to the osmotic pressure of the gel-solvent system is consistent with experimental observations that the swelling behavior of polyelectrolyte gels can be described by equations of state for neutral gels. Based on these results, we show and explain that a modified form of the Flory-Huggins model for nonionic polymer solutions, which accounts for neither electrostatic effects nor counterion excluded-volume effects, fits both experimental and simulated data for polyelectrolyte gels. The Flory-Huggins interaction parameters obtained from regression to the simulation data are characteristic of ideal polymer solutions, whereas the experimentally obtained interaction parameters, particularly that associated with the third virial coefficient, exhibit a significant departure from ideality, leading us to conclude that further enhancements to the simulation model, such as the inclusion of excess salt, the allowance for size asymmetric electrolytes, or the use of a distance-dependent solvent dielectricity model, may be required. Molecular simulations also reveal that the condensation of divalent counterions onto the polyelectrolyte network backbone occurs preferentially over that of monovalent counterions.

Inhibition of VEGF Signaling Reduces Diabetes-Exacerbated Brain Swelling, but Not Infarct Size, in Large Cerebral Infarction in Mice.

PubMed

Kim, Eunhee; Yang, Jiwon; Park, Keun Woo; Cho, Sunghee

2017-12-30

In light of repeated translational failures with preclinical neuroprotection-based strategies, this preclinical study reevaluates brain swelling as an important pathological event in diabetic stroke and investigates underlying mechanism of the comorbidity-enhanced brain edema formation. Type 2 (mild), type 1 (moderate), and mixed type 1/2 (severe) diabetic mice were subjected to transient focal ischemia. Infarct volume, brain swelling, and IgG extravasation were assessed at 3 days post-stroke. Expression of vascular endothelial growth factor (VEGF)-A, endothelial-specific molecule-1 (Esm1), and the VEGF receptor 2 (VEGFR2) was determined in the ischemic brain. Additionally, SU5416, a VEGFR2 inhibitor, was treated in the type 1/2 diabetic mice, and stroke outcomes were determined. All diabetic groups displayed bigger infarct volume and brain swelling compared to nondiabetic mice, and the increased swelling was disproportionately larger relative to infarct enlargement. Diabetic conditions significantly increased VEGF-A, Esm1, and VEGFR2 expressions in the ischemic brain compared to nondiabetic mice. Notably, in diabetic mice, VEGFR2 mRNA levels were positively correlated with brain swelling, but not with infarct volume. Treatment with SU5416 in diabetic mice significantly reduced brain swelling. The study shows that brain swelling is a predominant pathological event in diabetic stroke and that an underlying event for diabetes-enhanced brain swelling includes the activation of VEGF signaling. This study suggests consideration of stroke therapies aiming at primarily reducing brain swelling for subjects with diabetes.

Antisense oligodeoxynucleotide inhibition of a swelling-activated cation channel in osteoblast-like osteosarcoma cells

NASA Technical Reports Server (NTRS)

Duncan, R. L.; Kizer, N.; Barry, E. L.; Friedman, P. A.; Hruska, K. A.

1996-01-01

By patch-clamp analysis, we have shown that chronic, intermittent mechanical strain (CMS) increases the activity of stretch-activated cation channels of osteoblast-like UMR-106.01 cells. CMS also produces a swelling-activated whole-cell conductance (Gm) regulated by varying strain levels. We questioned whether the swelling-activated conductance was produced by stretch-activated cation channel activity. We have identified a gene involved in the increase in conductance by using antisense oligodeoxynucleotides (ODN) derived from the alpha 1-subunit genes of calcium channels found in UMR-106.01 cells (alpha1S, alpha1C, and alpha1D). We demonstrate that alpha 1C antisense ODNs abolish the increase in Gm in response to hypotonic swelling following CMS. Antisense ODNs to alpha1S and alpha1D, sense ODNs to alpha1C, and sham permeabilization had no effect on the conductance increase. In addition, during cell-attached patch-clamp studies, antisense ODNs to alpha1c completely blocked the swelling-activated and stretch-activated nonselective cation channel response to strain. Antisense ODNs to alpha1S treatment produced no effect on either swelling-activated or stretch-activated cation channel activity. There were differences in the stretch-activated and swelling-activated cation channel activity, but whether they represent different channels could not be determined from our data. Our data indicate that the alpha1C gene product is involved in the Gm and the activation of the swelling-activated cation channels induced by CMS. The possibility that swelling-activated cation channel genes are members of the calcium channel superfamily exists, but if alpha1c is not the swelling-activated cation channel itself, then its expression is required for induction of swelling-activated cation channel activity by CMS.

Early awareness of cerebrospinal fluid hypovolemia after craniotomy for microsurgical aneurysmal clipping.

PubMed

Kawahara, Ichiro; Tsutsumi, Keisuke; Matsunaga, Yuki; Takahata, Hideaki; Ono, Tomonori; Toda, Keisuke; Baba, Hiroshi

2013-08-01

Mild cerebrospinal fluid (CSF) hypovolemia is a well-known clinical entity, but critical CSF hypovolemia that can cause transtentorial herniation is an unusual and rare clinical entity that occurs after craniotomy. We investigated CSF hypovolemia after microsurgical aneurysmal clipping for subarachnoid hemorrhage (SAH). This study included 144 consecutive patients with SAH. Lumbar drainage (LD) was inserted after general anesthesia or postoperatively as a standard perioperative protocol. CSF hypovolemia diagnosis was based on three criteria. Eleven patients (7.6%) were diagnosed with CSF hypovolemia according to diagnostic criteria in a postoperative range of 0-8 days. In all patients, signs or symptoms of CSF hypovolemia improved within 24 hours by clamping LD and using the Trendelenburg position. As a cause of acute clinical deterioration after aneurysmal clipping, CSF hypovolemia is likely under-recognized, and may actually be misdiagnosed as vasospasm or brain swelling. We should always take the etiology of CSF hypovolemia into consideration, and especially pay attention in patients with pneumocephalus and subdural fluid collection alongside brain sag on computed tomography. These patients are at higher risk developing of pressure gradients between their cranial and spinal compartments, and therefore, brain sagging after LD, than after ventricular drainage. We should be vigilant to strictly manage LD so as not to produce high pressure gradients.

The Darfur Swell, Africa: Gravity constraints on its isostatic compensation

NASA Astrophysics Data System (ADS)

Crough, S. Thomas

The free-air gravity anomaly observed over the Darfur Swell is explainable by local isostatic balance with a root approximately 50 km deep on average. This root depth is similar to that inferred beneath other African domes and beneath oceanic midplate swells, suggesting that the Darfur Swell is a hotspot uplift created by lithospheric reheating.

Process for treating biomass

DOEpatents

Campbell, Timothy J; Teymouri, Farzaneh

2015-11-04

This invention is directed to a process for treating biomass. The biomass is treated with a biomass swelling agent within the vessel to swell or rupture at least a portion of the biomass. A portion of the swelling agent is removed from a first end of the vessel following the treatment. Then steam is introduced into a second end of the vessel different from the first end to further remove swelling agent from the vessel in such a manner that the swelling agent exits the vessel at a relatively low water content.

Process for treating biomass

DOEpatents

Campbell, Timothy J.; Teymouri, Farzaneh

2015-08-11

This invention is directed to a process for treating biomass. The biomass is treated with a biomass swelling agent within the vessel to swell or rupture at least a portion of the biomass. A portion of the swelling agent is removed from a first end of the vessel following the treatment. Then steam is introduced into a second end of the vessel different from the first end to further remove swelling agent from the vessel in such a manner that the swelling agent exits the vessel at a relatively low water content.

Process for treating biomass

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

Campbell, Timothy J.; Teymouri, Farzaneh

This invention is directed to a process for treating biomass. The biomass is treated with a biomass swelling agent within the vessel to swell or rupture at least a portion of the biomass. A portion of the swelling agent is removed from a first end of the vessel following the treatment. Then steam is introduced into a second end of the vessel different from the first end to further remove swelling agent from the vessel in such a manner that the swelling agent exits the vessel at a relatively low water content.

Development of Ultrafiltration Membrane-Separation Technology for Energy-Efficient Water Treatment and Desalination Process

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

Yim, Woosoon; Bae, Chulsung

The growing scarcity of fresh water is a major political and economic challenge in the 21st century. Compared to thermal-based distillation technique of water production, pressure driven membrane-based water purification process, such as ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO), can offer more energy-efficient and environmentally friendly solution to clean water production. Potential applications also include removal of hazardous chemicals (i.e., arsenic, pesticides, organics) from water. Although those membrane-separation technologies have been used to produce drinking water from seawater (desalination) and non-traditional water (i.e., municipal wastewater and brackish groundwater) over the last decades, they still have problems in ordermore » to be applied in large-scale operations. Currently, a major huddle of membrane-based water purification technology for large-scale commercialization is membrane fouling and its resulting increases in pressure and energy cost of filtration process. Membrane cleaning methods, which can restore the membrane properties to some degree, usually cause irreversible damage to the membranes. Considering that electricity for creating of pressure constitutes a majority of cost (~50%) in membrane-based water purification process, the development of new nano-porous membranes that are more resistant to degradation and less subject to fouling is highly desired. Styrene-ethylene/butylene-styrene (SEBS) block copolymer is one of the best known block copolymers that induces well defined morphologies. Due to the polarity difference of aromatic styrene unit and saturated ethylene/butylene unit, these two polymer chains self-assemble each other and form different phase-separated morphologies depending on the ratios of two polymer chain lengths. Because the surface of SEBS is hydrophobic which easily causes fouling of membrane, incorporation of ionic group (e,g, sulfonate) to the polymer is necessary to reduces fouling. Recently, sulfonated SEBS became commercially available and has been extensively explored for membrane-mediated water purification technology. The sulfonated block copolymer creates a well developed nano-sale phase-separated morphologies composed of hydrophilic domains (sulfonated polystyrene) and hydrophobic domains (polyethylene/polybutylene). The hydrophilic domains determines transport properties (water transport, salt and/or ion rejection, etc) and the hydrophobic domains provides mechanical stability of the membrane. Unfortunately, a high degree of sulfonation of SEBS induces excessive swelling and deterioration of mechanical stability of the membrane. In an effort to develop robust polymeric membrane materials for water purification technology, phosphonic acid-functionalized SEBS membranes are investigated during this report period. In compare to sulfonated polymers, the corresponding phosphonated polymers are known to swell less because of the formation of extensive hydrogen bonding networks between phosphonates. In addition to the expected better mechanical stability, phosphonated polymers has another advantage over sulfonated polymers for the use water purification membrane; each phosphonate can accommodate two ions while each sulfonate accommodates only one ion. Membrane properties (ion type, ionic density, etc) of new membranes will be studied and their separation performance will be evaluated in water purification and desalination process. Through systematic study of the relationship of chemical structure–surface property–membrane performance, we aim to better understand the nature of membrane fouling and develop more fouling-resistant water purification membranes. The basic understanding of this relationship will lead to the development of advanced membrane materials which can offer a solution to environmentally sustainable production of fresh water.« less

Effect of Guci powder on toe swelling induced by egg white in rats

NASA Astrophysics Data System (ADS)

Xie, Guoqi; Hao, Shaojun; Shen, Huiling; Ma, Zhenzhen; Zhang, Xuehui; Zhang, Zhengchen

2018-04-01

To observe the effect of Guci Powder on foot swelling induced by egg white in rats. 50 male rats were randomly divided into normal saline group (n=10), white vinegar group (n=10) and Guning lotion group (n=10). There were 10 rats in the high-dose group and 10 in the low-dose group. The rats in each group were treated with the drug on the left and right feet of the rats. 0.5 hours after the last administration, the rats in each group were inflamed. The left hindsole plantar volume was measured respectively, so that the difference of the posterior toe volume before inflammation was taken as the swelling degree, and the swelling degree of each group was calculated. Compared with physiological saline group, the rats' egg white toe swelling (P<0.01) was significantly inhibited at 0.5˜6h after administration. The swelling of egg white toe in rats was inhibited at 0.5˜2h (P<0.05). Bone spur powder has a good intervention effect on the model of toe swelling induced by egg white in rats, and the external application of bone spur powder has anti-inflammatory and swelling effect.

Deformation mechanisms in a coal mine roadway in extremely swelling soft rock.

PubMed

Li, Qinghai; Shi, Weiping; Yang, Renshu

2016-01-01

The problem of roadway support in swelling soft rock was one of the challenging problems during mining. For most geological conditions, combinations of two or more supporting approaches could meet the requirements of most roadways; however, in extremely swelling soft rock, combined approaches even could not control large deformations. The purpose of this work was to probe the roadway deformation mechanisms in extremely swelling soft rock. Based on the main return air-way in a coal mine, deformation monitoring and geomechanical analysis were conducted, as well as plastic zone mechanical model was analysed. Results indicated that this soft rock was potentially very swelling. When the ground stress acted alone, the support strength needed in situ was not too large and combined supporting approaches could meet this requirement; however, when this potential released, the roadway would undergo permanent deformation. When the loose zone reached 3 m within surrounding rock, remote stress p ∞ and supporting stress P presented a linear relationship. Namely, the greater the swelling stress, the more difficult it would be in roadway supporting. So in this extremely swelling soft rock, a better way to control roadway deformation was to control the releasing of surrounding rock's swelling potential.

Swelling kinetics and electrical charge transport in PEDOT:PSS thin films exposed to water vapor.

PubMed

Sarkar, Biporjoy; Jaiswal, Manu; Satapathy, Dillip K

2018-06-06

We report the swelling kinetics and evolution of the electrical charge transport in poly(3,4-ethylene dioxythiophene) polystyrene sulfonate (PEDOT:PSS) thin films subjected to water vapor. Polymer films swell by the diffusion of water vapor and are found to undergo structural relaxations. Upon exposure to water vapor, primarily the hygroscopic PSS shell, which surrounds the conducting PEDOT-rich cores, takes up water vapor and subsequently swells. We found that the degree of swelling largely depends on the PEDOT to PSS ratio. Swelling driven microscopic rearrangement of the conducting PEDOT-rich cores in the PSS matrix strongly influences the electrical charge transport of the polymer film. Swelling induced increase as well as decrease of electrical resistance are observed in polymer films having different PEDOT to PSS ratio. This anomalous charge transport behavior in PEDOT:PSS films is reconciled by taking into account the contrasting swelling behavior of the PSS and the conducting PEDOT-rich cores leading to spatial segregation of PSS in films with PSS as a minority phase and by a net increase in mean separation between conducting PEDOT-rich cores for films having abundance of PSS.

Swelling kinetics and electrical charge transport in PEDOT:PSS thin films exposed to water vapor

NASA Astrophysics Data System (ADS)

Sarkar, Biporjoy; Jaiswal, Manu; Satapathy, Dillip K.

2018-06-01

We report the swelling kinetics and evolution of the electrical charge transport in poly(3,4-ethylene dioxythiophene) polystyrene sulfonate (PEDOT:PSS) thin films subjected to water vapor. Polymer films swell by the diffusion of water vapor and are found to undergo structural relaxations. Upon exposure to water vapor, primarily the hygroscopic PSS shell, which surrounds the conducting PEDOT-rich cores, takes up water vapor and subsequently swells. We found that the degree of swelling largely depends on the PEDOT to PSS ratio. Swelling driven microscopic rearrangement of the conducting PEDOT-rich cores in the PSS matrix strongly influences the electrical charge transport of the polymer film. Swelling induced increase as well as decrease of electrical resistance are observed in polymer films having different PEDOT to PSS ratio. This anomalous charge transport behavior in PEDOT:PSS films is reconciled by taking into account the contrasting swelling behavior of the PSS and the conducting PEDOT-rich cores leading to spatial segregation of PSS in films with PSS as a minority phase and by a net increase in mean separation between conducting PEDOT-rich cores for films having abundance of PSS.

Spontaneous rupture of the renal pelvis presenting as an urinoma in locally advanced rectal cancer

PubMed Central

Garg, Pankaj Kumar; Mohanty, Debajyoti; Rathi, Vinita; Jain, Bhupendra Kumar

2014-01-01

A 29-year-old gentleman underwent a transverse colostomy for intestinal obstruction caused by advanced rectal carcinoma. On the 5th postoperative day, the patient developed a painful swelling on the right side of the abdomen. The contrast enhanced computed tomography of the abdomen revealed a right sided hydronephrosis, a large rent in the renal pelvis, and a large retroperitoneal fluid collection on the right side. Percutaneous nephrostomy and pigtail catheter drainage of the urinoma led to resolution of abdominal swelling. Development of a urinoma as a consequence of rectal carcinoma is highly unusual. Prompt imaging for confirmation of diagnosis, decompression of the renal pelvicalyceal system, and drainage of the urinoma limits morbidity. PMID:24749123

Development of visible-light responsive and mechanically enhanced "smart" UCST interpenetrating network hydrogels.

PubMed

Xu, Yifei; Ghag, Onkar; Reimann, Morgan; Sitterle, Philip; Chatterjee, Prithwish; Nofen, Elizabeth; Yu, Hongyu; Jiang, Hanqing; Dai, Lenore L

2017-12-20

An interpenetrating polymer network (IPN), chlorophyllin-incorporated environmentally responsive hydrogel was synthesized and exhibited the following features: enhanced mechanical properties, upper critical solution temperature (UCST) swelling behavior, and promising visible-light responsiveness. Poor mechanical properties are known challenges for hydrogel-based materials. By forming an interpenetrating network between polyacrylamide (PAAm) and poly(acrylic acid) (PAAc) polymer networks, the mechanical properties of the synthesized IPN hydrogels were significantly improved compared to hydrogels made of a single network of each polymer. The formation of the interpenetrating network was confirmed by Fourier Transform Infrared Spectroscopy (FTIR), the analysis of glass transition temperature, and a unique UCST responsive swelling behavior, which is in contrast to the more prevalent lower critical solution temperature (LCST) behaviour of environmentally responsive hydrogels. The visible-light responsiveness of the synthesized hydrogel also demonstrated a positive swelling behavior, and the effect of incorporating chlorophyllin as the chromophore unit was observed to reduce the average pore size and further enhance the mechanical properties of the hydrogel. This interpenetrating network system shows potential to serve as a new route in developing "smart" hydrogels using visible-light as a simple, inexpensive, and remotely controllable stimulus.

How Much Do Ultrathin Polymers with Intrinsic Microporosity Swell in Liquids?

PubMed

Ogieglo, Wojciech; Ghanem, Bader; Ma, Xiaohua; Pinnau, Ingo; Wessling, Matthias

2016-10-06

As synthetic membrane materials, polymers with intrinsic microporosity (PIMs) have demonstrated unprecedented permeation and molecular-separation properties. Here, we report the swelling characteristics of submicron-thick supported films of spirobisindane-based PIMs, PIM-1 and PIM-6FDA-OH, for six organic solvents and water using in situ spectroscopic ellipsometry. Surprisingly, PIMs swell significantly in most organic solvents, with swelling factors (SF = h swollen /h dry ) as high as 2.5. This leads to the loss of the ultrarigid character of the polymer and produces equilibrated liquid-like swollen films. Filling of the excess frozen-in fractional free volume with liquid was discovered next to swelling-induced polymer matrix dilation. Water hardly swells the polymer matrix, but it penetrates into the intrinsic microporous structure. This study is the first to provide fundamental swelling data for PIMs, leading to better comprehension of their permeation properties. Such an understanding is indispensable for applications such as solvent filtration, natural-gas separation, and ion retention in flow batteries.

Modeling thermal and irradiation-induced swelling effects on the integrity of Ti3SiC2/SiC joints

NASA Astrophysics Data System (ADS)

Nguyen, Ba Nghiep; Henager, Charles H.; Kurtz, Richard J.

2017-11-01

Previously, results for CVD-SiC joined by a solid state displacement reaction to form a dual-phase SiC/MAX phase joint subsequently irradiated at 800 °C to 5 dpa indicated some cracking in the joint. This paper elucidates the cracking origin by developing a model that accounts for differential thermal expansion and irradiation-induced swelling between the substrate and joint materials by using a continuum damage mechanics approach with support from micromechanical modeling. Damage accumulation in joined specimens irradiated at four temperatures (300 °C, 400 °C, 500 °C and 800 °C) is analyzed. We assume the experimental irradiation dose is sufficient to cause saturation swelling in SiC. The analyses indicate that the SiC/MAX joint survives irradiation-induced swelling at all the irradiation temperatures considered. The joint experiences only minor damage when heated to and irradiated at 800 °C as well as cooling to room temperature. The prediction agrees with the experimental findings available for this case. However, the joint heated to 300 °C suffers severe damage during irradiation-induced swelling at this temperature, and additional damage after cooling to room temperature. Irradiation at 400 °C and subsequent cooling to room temperature produced similar damage to the irradiation 300 °C case, but to a lesser extent. The joint heated to 500 °C and irradiated at this temperature suffered only very minor damage, but further moderate damage occurred after cooling to room temperature.

A dual-phase microstructural approach to damage and fracture of Ti3SiC2/SiC joints

NASA Astrophysics Data System (ADS)

Nguyen, Ba Nghiep; Henager, Charles H.; Kurtz, Richard J.

2018-02-01

The microcracking mechanisms responsible for Ti3SiC2/SiC joint damage observed at the macroscopic scale after neutron irradiation experiments are investigated in detail. A dual-phase microstructural approach to damage and fracture of Ti3SiC2/SiC joints is developed that uses a finely discretized two-phase domain based on a digital image of an actual microstructure involving embedded Ti3SiC2 and SiC phases. The behaviors of SiC and Ti3SiC2 in the domain are described by the continuum damage mechanics (CDM) model reported in Nguyen et al., J. Nucl. Mater., 2017, 495:504-515. This CDM model describes microcracking damage in brittle ceramics caused by thermomechanical loading and irradiation-induced swelling. The dual-phase microstructural model is applied to predict the microcracking mechanisms occurring in a typical Ti3SiC2/SiC joint subjected to heating to 800 °C followed by irradiation-induced swelling at this temperature and cooling to room temperature after the applied swelling has reached the maximum swelling levels observed in the experiments for SiC and Ti3SiC2. The model predicts minor damage of the joint after heating but significant microcracking in the SiC phase and along the boundaries between SiC and Ti3SiC2 as well as along the bonding joint during irradiation-induced swelling and cooling to room temperature. These predictions qualitatively agree with the limited experimental observations of joint damage at this irradiation temperature.

Advanced fuels modeling: Evaluating the steady-state performance of carbide fuel in helium-cooled reactors using FRAPCON 3.4

NASA Astrophysics Data System (ADS)

Hallman, Luther, Jr.

Uranium carbide (UC) has long been considered a potential alternative to uranium dioxide (UO2) fuel, especially in the context of Gen IV gas-cooled reactors. It has shown promise because of its high uranium density, good irradiation stability, and especially high thermal conductivity. Despite its many benefits, UC is known to swell at a rate twice that of UO2. However, the swelling phenomenon is not well understood, and we are limited to a weak empirical understanding of the swelling mechanism. One suggested cladding for UC is silicon carbide (SiC), a ceramic that demonstrates a number of desirable properties. Among them are an increased corrosion resistance, high mechanical strength, and irradiation stability. However, with increased temperatures, SiC exhibits an extremely brittle nature. The brittle behavior of SiC is not fully understood and thus it is unknown how SiC would respond to the added stress of a swelling UC fuel. To better understand the interaction between these advanced materials, each has been implemented into FRAPCON, the preferred fuel performance code of the Nuclear Regulatory Commission (NRC); additionally, the material properties for a helium coolant have been incorporated. The implementation of UC within FRAPCON required the development of material models that described not only the thermophysical properties of UC, such as thermal conductivity and thermal expansion, but also models for the swelling, densification, and fission gas release associated with the fuel's irradiation behavior. This research is intended to supplement ongoing analysis of the performance and behavior of uranium carbide and silicon carbide in a helium-cooled reactor.

Modeling thermal and irradiation-induced swelling effects on the integrity of Ti 3SiC 2/SiC joints

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

Nguyen, Ba Nghiep; Henager, Charles H.; Kurtz, Richard J.

Previously, results for CVD-SiC joined by a solid state displacement reaction to form a dual-phase SiC/MAX phase joint subsequently irradiated at 800 °C to 5 dpa indicated some cracking in the joint. Here, this paper elucidates the cracking origin by developing a model that accounts for differential thermal expansion and irradiation-induced swelling between the substrate and joint materials by using a continuum damage mechanics approach with support from micromechanical modeling. Damage accumulation in joined specimens irradiated at four temperatures (300 °C, 400 °C, 500 °C and 800 °C) is analyzed. We assume the experimental irradiation dose is sufficient to causemore » saturation swelling in SiC. The analyses indicate that the SiC/MAX joint survives irradiation-induced swelling at all the irradiation temperatures considered. The joint experiences only minor damage when heated to and irradiated at 800 °C as well as cooling to room temperature. The prediction agrees with the experimental findings available for this case. However, the joint heated to 300 °C suffers severe damage during irradiation-induced swelling at this temperature, and additional damage after cooling to room temperature. Irradiation at 400 °C and subsequent cooling to room temperature produced similar damage to the irradiation 300 °C case, but to a lesser extent. Finally, the joint heated to 500 °C and irradiated at this temperature suffered only very minor damage, but further moderate damage occurred after cooling to room temperature.« less

Modeling thermal and irradiation-induced swelling effects on the integrity of Ti 3SiC 2/SiC joints

DOE PAGES

Nguyen, Ba Nghiep; Henager, Charles H.; Kurtz, Richard J.

2017-09-08

Previously, results for CVD-SiC joined by a solid state displacement reaction to form a dual-phase SiC/MAX phase joint subsequently irradiated at 800 °C to 5 dpa indicated some cracking in the joint. Here, this paper elucidates the cracking origin by developing a model that accounts for differential thermal expansion and irradiation-induced swelling between the substrate and joint materials by using a continuum damage mechanics approach with support from micromechanical modeling. Damage accumulation in joined specimens irradiated at four temperatures (300 °C, 400 °C, 500 °C and 800 °C) is analyzed. We assume the experimental irradiation dose is sufficient to causemore » saturation swelling in SiC. The analyses indicate that the SiC/MAX joint survives irradiation-induced swelling at all the irradiation temperatures considered. The joint experiences only minor damage when heated to and irradiated at 800 °C as well as cooling to room temperature. The prediction agrees with the experimental findings available for this case. However, the joint heated to 300 °C suffers severe damage during irradiation-induced swelling at this temperature, and additional damage after cooling to room temperature. Irradiation at 400 °C and subsequent cooling to room temperature produced similar damage to the irradiation 300 °C case, but to a lesser extent. Finally, the joint heated to 500 °C and irradiated at this temperature suffered only very minor damage, but further moderate damage occurred after cooling to room temperature.« less

Temporal expression and mitochondrial localization of a Foxp2 isoform lacking the forkhead domain in developing Purkinje cells.

PubMed

Tanabe, Yuko; Fujiwara, Yuji; Matsuzaki, Ayumi; Fujita, Eriko; Kasahara, Tadashi; Yuasa, Shigeki; Momoi, Takashi

2012-07-01

FOXP2, a forkhead box-containing transcription factor, forms homo- or hetero-dimers with FOXP family members and localizes to the nucleus, while FOXP2(R553H), which contains a mutation related to speech/language disorders, features reduced DNA binding activity and both cytoplasmic and nuclear localization. In addition to being a loss-of-function mutation, it is possible that FOXP2(R553H) also may act as a gain-of-function mutation to inhibit the functions of FOXP2 isoforms including FOXP2Ex10+ lacking forkhead domain. Foxp2(R552H) knock-in mouse pups exhibit impaired ultrasonic vocalization and poor dendritic development in Purkinje cells. However, expressions of Foxp2 isoforms in the developing Purkinje are unclear. The appearance of 'apical cytoplasmic swelling' (mitochondria-rich regions that are the source of budding processes) correlates with dendritic development of Purkinje cells. In the present study, we focused on Foxp2 isoforms localizing to the apical cytoplasmic swelling and identified two isoforms lacking forkhead domain: Foxp2Ex12+ and Foxp2Ex15. They partly localized to the membrane fraction that includes mitochondria. Foxp2Ex12+ mainly localized to the apical cytoplasmic swelling in early developing Purkinje cells at the stellate stage (P2-P4). Mitochondrial localization of Foxp2Ex12+ in Purkinje cells was confirmed by immune-electron microscopic analysis. Foxp2Ex12+ may play a role in dendritic development in Purkinje cells. © 2011 The Authors. Journal of Neurochemistry © 2011 International Society for Neurochemistry.

DART model for irradiation-induced swelling of dispersion fuel elements including aluminum-fuel interaction

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

Rest, J.; Hofman, G.L.

1997-12-01

The Dispersion Analysis Research Tool (DART) contains models for fission-gas-induced fuel swelling, interaction of fuel with the matrix aluminum, for the resultant reaction-product swelling, and for the calculation of the stress gradient within the fuel particle. The effects of an aluminide shell on fuel particle swelling are evaluated. Validation of the model is demonstrated by a comparison of DART calculations of fuel swelling of U{sub 3}SiAl-Al and U{sub 3}Si{sub 2}-Al for various dispersion fuel element designs with the data.

DART model for irradiation-induced swelling of uranium silicide dispersion fuel elements

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

Rest, J.; Hofman, G.L.

1999-04-01

Models for the interaction of uranium silicide dispersion fuels with an aluminum matrix, for the resultant reaction product swelling, and for the calculation of the stress gradient within the fuel particles are described within the context of DART fission-gas-induced swelling models. The effects of an aluminide shell on fuel particle swelling are evaluated. Validation of the model is demonstrated by comparing DART calculations with irradiation data for the swelling of U{sub 3}SiAl-Al and U{sub 3}Si{sub 2}-Al in variously designed dispersion fuel elements.

Ascites: A Common Problem in People with Cirrhosis

MedlinePlus

... liver (portal hypertension) and a decrease in liver function caused by scarring of the liver, i.e., cirrhosis. Symptoms Most patients who develop ascites notice abdominal distension and rapid weight gain. Some people also develop swelling of ankles and ...

Current Treatment Options for Penile Fractures

PubMed Central

Jack, Gregory S; Garraway, Isla; Reznichek, Richard; Rajfer, Jacob

2004-01-01

The diagnosis of “penile fracture” describes the traumatic rupture of the tunica albuginea of an erect penis. Penile fractures typically occur when the engorged penile corpora are forced to buckle and literally “pop” under the pressure of a blunt sexual trauma. Patients typically describe immediate detumescence, severe pain, and swelling as a result of the injury. Prompt surgical exploration and corporal repair is the most efficacious therapy. Although a majority of cases can be diagnosed from the history and physical examination alone, radiographic studies, including retrograde urethrography and corporal cavernosography can aid in the diagnosis of unusual cases. PMID:16985591

Modular microfluidic valve structures based on reversible thermoresponsive ionogel actuators.

PubMed

Benito-Lopez, Fernando; Antoñana-Díez, Marta; Curto, Vincenzo F; Diamond, Dermot; Castro-López, Vanessa

2014-09-21

This paper reports for the first time the use of a cross-linked poly(N-isopropylacrylamide) ionogel encapsulating the ionic liquid 1-ethyl-3-methylimidazolium ethyl sulphate as a thermoresponsive and modular microfluidic valve. The ionogel presents superior actuation behaviour to its equivalent hydrogel. Ionogel swelling and shrinking mechanisms and kinetics are investigated as well as the performance of the ionogel when integrated as a valve in a microfluidic device. The modular microfluidic valve demonstrates fully a reversible on-off behaviour without failure for up to eight actuation cycles and a pressure resistance of 1100 mbar.

Mixed messages: wild female bonobos show high variability in the timing of ovulation in relation to sexual swelling patterns.

PubMed

Douglas, Pamela Heidi; Hohmann, Gottfried; Murtagh, Róisín; Thiessen-Bock, Robyn; Deschner, Tobias

2016-06-30

The evolution of primate sexual swellings and their influence on mating strategies have captivated the interest of biologists for over a century. Across the primate order, variability in the timing of ovulation with respect to females' sexual swelling patterns differs greatly. Since sexual swellings typically function as signals of female fecundity, the temporal relation between ovulation and sexual swellings can impact the ability of males to pinpoint ovulation and thereby affect male mating strategies. Here, we used endocrine parameters to detect ovulation and examined the temporal relation between the maximum swelling phase (MSP) and ovulation in wild female bonobos (Pan paniscus). Data were collected at the Luikotale field site, Democratic Republic of Congo, spanning 36 months. Observational data from 13 females were used to characterise female swelling cycles (N = 70). Furthermore, we measured urinary oestrone and pregnanediol using liquid chromatography-tandem mass spectrometry, and used pregnanediol to determine the timing of ovulation in 34 cycles (N = 9 females). We found that the duration of females' MSP was highly variable, ranging from 1 to 31 days. Timing of ovulation varied considerably in relation to the onset of the MSP, resulting in a very low day-specific probability of ovulation and fecundity across female cycles. Ovulation occurred during the MSP in only 52.9 % of the analysed swelling cycles, and females showed regular sexual swelling patterns in N = 8 swelling cycles where ovulation did not occur. These findings reveal that sexual swellings of bonobos are less reliable indicators of ovulation compared to other species of primates. Female bonobos show unusual variability in the duration of the MSP and in the timing of ovulation relative to the sexual swelling signal. These data are important for understanding the evolution of sexual signals, how they influence male and female mating strategies, and how decoupling visual signals of fecundity from the periovulatory period may affect intersexual conflict. By prolonging the period during which males would need to mate guard females to ascertain paternity, the temporal variability of this signal may constrain mate-guarding efforts by male bonobos.

Bowers Swell: Evidence for a zone of compressive deformation concentric with Bowers Ridge, Bering Sea

USGS Publications Warehouse

Marlow, M. S.; Cooper, A. K.; Dadisman, S.V.; Geist, E.L.; Carlson, P.R.

1990-01-01

Bowers Swell is a newly discovered bathymetric feature which is up to 90 m high, between 12 and 20 km wide, and which extends arcuately about 400 km along the northern and eastern sides of Bowers Ridge. The swell was first revealed on GLORIA sonographs and subsequently mapped on seismic reflection and 3.5 kHz bathymetric profiles. These geophysical data show that the swell caps an arcuate anticlinal ridge, which is composed of deformed strata in an ancient trench on the northern and eastern sides of Bowers Ridge. The trench fill beneath the swell is actively deforming, as shown by faulting of the sea floor and by thinning of the strata across the crest of the swell. Thinning and faulting of the trench strata preclude an origin for the swell by simple sediment draping over an older basement high. We considered several models for the origin of Bowers Swell, including folding and uplift of the underlying trench sediment during the interaction between the Pacific plate beneath the Aleutian Ridge and a remnant oceanic slab beneath Bowers Ridge. However, such plate motions should generate extensive seismicity beneath Bowers Ridge, which is aseismic, and refraction data do not show any remnant slab beneath Bowers Ridge. Another origin considered for Bowers Swell invokes sediment deformation resulting from differential loading and diapirism in the trench fill. However, diapirism is not evident on seismic reflection profiles across the swell. We favour a model in which sediment deformation and swell formation resulted from a few tens of kilometers of low seismicity motion by intraplate crustal blocks beneath the Aleutian Basin. This motion may result from the translation of blocks in western Alaska to the south-west, forcing the movement of the Bering Sea margin west of Alaska into the abyssal Aleutian Basin. ?? 1990.

Adsorption of nucleotides onto ferromagnesian phyllosilicates: Significance for the origin of life

NASA Astrophysics Data System (ADS)

Pedreira-Segade, Ulysse; Feuillie, Cécile; Pelletier, Manuel; Michot, Laurent J.; Daniel, Isabelle

2016-03-01

The concentration of prebiotic organic building blocks may have promoted the formation of biopolymers in the environment of the early Earth. We therefore studied the adsorption of RNA monomers AMP, GMP, CMP, and UMP, and DNA monomers dGMP, dCMP, and TMP, on minerals that were abundant in the early Earth environment as the result of aqueous or hydrothermal alteration of the primitive oceanic crust. We focused our study on swelling clays, i.e. nontronite and montmorillonite, and non-swelling phyllosilicates, i.e. pyrophyllite, chlorite, lizardite and chrysotile suspended in an aqueous saline solution analog to seawater. In this reference study, adsorption experiments were carried out under standard conditions of pressure and temperature and controlled pH. Under such conditions, this work is also relevant to the preservation of nucleic acids in Fe-Mg-rich terrestrial and Martian soils. We compared the adsorption of the different monomers on individual minerals, as well as the adsorption of single monomers on the whole suite of minerals. We found that DNA monomers adsorb much more strongly than RNA monomers, and that any monomer containing the G nucleobase adsorbed more strongly than one containing the C nucleobase. At high surface loadings (greater than about 1 mM monomer in aqueous solution) we also found a dramatic increase in the slope of adsorption isotherm on the swelling clays, leading to large increases in the amounts adsorbed. Data were processed in order to understand the adsorption mechanism of nucleotides onto mineral surfaces. We infer that all nucleotides behave as homologous molecules in regard to their adsorption onto the studied mineral surfaces. At low to moderate surface loadings, their adsorption is best explained by a single mechanism common to the suite of minerals of the present study. At pH 7, adsorption certainly proceeds by ligand exchange between the phosphate group and the hydroxyls of the broken edges of phyllosilicates leading to the saturation of lateral surfaces. Below pH 4, swelling clays also adsorb nucleotides through cation exchange on basal surfaces, whereas non-swelling phyllosilicates do not. However, at high surface loadings an additional mechanism stabilizing adsorption occurs. Given the proposed adsorption mechanisms, the possibility of a favorable polymerization at the mineral-water interface is discussed. We propose that Fe-Mg rich phyllosilicates tightly bind nucleotides, under ambient conditions, and concentrate them up to 1000 times the solution concentration upon saturation. Nontronites have the most diverse and favorable adsorption behaviors and could have helped to the concentration and polymerization of nucleotides under primitive Earth-like conditions.

Compression Therapy: Clinical and Experimental Evidence

PubMed Central

2012-01-01

Aim: A review is given on the different tools of compression therapy and their mode of action. Methods: Interface pressure and stiffness of compression devices, alone or in combination can be measured in vivo. Hemodynamic effects have been demonstrated by measuring venous volume and flow velocity using MRI, Duplex and radioisotopes, venous reflux and venous pumping function using plethysmography and phlebodynamometry. Oedema reduction can be measured by limb volumetry. Results: Compression stockings exerting a pressure of ~20 mmHg on the distal leg are able to increase venous blood flow velocity in the supine position and to prevent leg swelling after prolonged sitting and standing. In the upright position, an interface pressure of more than 50 mmHg is needed for intermittent occlusion of incompetent veins and for a reduction of ambulatory venous hypertension during walking. Such high intermittent interface pressure peaks exerting a “massaging effect” may rather be achieved by short stretch multilayer bandages than by elastic stockings. Conclusion: Compression is a cornerstone in the management of venous and lymphatic insufficiency. However, this treatment modality is still underestimated and deserves better understanding and improved educational programs, both for patients and medical staff. PMID:23641263

Fission product release and survivability of UN-kernel LWR TRISO fuel

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

T. M. Besmann; M. K. Ferber; H.-T. Lin

2014-05-01

A thermomechanical assessment of the LWR application of TRISO fuel with UN kernels was performed. Fission product release under operational and transient temperature conditions was determined by extrapolation from fission product recoil calculations and limited data from irradiated UN pellets. Both fission recoil and diffusive release were considered and internal particle pressures computed for both 650 and 800 um diameter kernels as a function of buffer layer thickness. These pressures were used in conjunction with a finite element program to compute the radial and tangential stresses generated within a TRISO particle undergoing burnup. Creep and swelling of the inner andmore » outer pyrolytic carbon layers were included in the analyses. A measure of reliability of the TRISO particle was obtained by computing the probability of survival of the SiC barrier layer and the maximum tensile stress generated in the pyrolytic carbon layers from internal pressure and thermomechanics of the layers. These reliability estimates were obtained as functions of the kernel diameter, buffer layer thickness, and pyrolytic carbon layer thickness. The value of the probability of survival at the end of irradiation was inversely proportional to the maximum pressure.« less

Effect of high hydrostatic pressure on the supramolecular structure of corn starch with different amylose contents.

PubMed

Yang, Zhi; Swedlund, Peter; Hemar, Yacine; Mo, Guang; Wei, Yanru; Li, Zhihong; Wu, Zhonghua

2016-04-01

Corn starches with amylose contents ranging from 0 to 80% were suspended in 60 wt% water or ethanol and subjected to high hydrostatic pressure (HHP) up to 600 MPa. The impact of HHP treatment on the granule morphology, lamellae structures, and crystalline characteristics were examined with a combination of SAXS, WAXS and optical microscopy. All starch dispersed in water showed a decrease in area of the lamellar peak in the SAXS data at q∼0.6 nm(-1). The lamellae thickness (d) increased for pressurized waxy, normal, and Gelose80 corn starches, suggesting water is forced into starch lamellae during HHP. However, for Gelose50 corn starch, the d remained constant over the whole pressure range and light microscopy showed no obvious granule swelling. WAXS studies demonstrated that HHP partially converted A-type starches (waxy and normal corn) to starches with a faint B-type pattern while starches with a B+V-type pattern (Gelose50 and Gelose80), were not affected by HHP. All corn starches suspended in ethanol showed no detectable changes in either granule morphology, or the fractal, the lamellae, and the crystalline structures. Copyright © 2016 Elsevier B.V. All rights reserved.

Hypotonic swelling promotes nitric oxide release in cardiac ventricular myocytes: impact on swelling-induced negative inotropic effect

PubMed Central

Gonano, Luis Alberto; Morell, Malena; Burgos, Juan Ignacio; Dulce, Raul Ariel; De Giusti, Verónica Celeste; Aiello, Ernesto Alejandro; Hare, Joshua Michael; Vila Petroff, Martin

2014-01-01

Aims Cardiomyocyte swelling occurs in multiple pathological situations and has been associated with contractile dysfunction, cell death, and enhanced propensity to arrhythmias. We investigate whether hypotonic swelling promotes nitric oxide (NO) release in cardiomyocytes, and whether it impacts on swelling-induced contractile dysfunction. Methods and results Superfusing rat cardiomyocytes with a hypotonic solution (HS; 217 mOsm), increased cell volume, reduced myocyte contraction and Ca2+ transient, and increased NO-sensitive 4-amino-5-methylamino-2′,7′-difluorofluorescein diacetate (DAF-FM) fluorescence. When cells were exposed to HS + 2.5 mM of the NO synthase inhibitor l-NAME, cell swelling occurred in the absence of NO release. Swelling-induced NO release was also prevented by the nitric oxide synthase 1 (NOS1) inhibitor, nitroguanidine, and significantly reduced in NOS1 knockout mice. Additionally, colchicine (inhibitor of microtubule polymerization) prevented the increase in DAF-FM fluorescence induced by HS, indicating that microtubule integrity is necessary for swelling-induced NO release. The swelling-induced negative inotropic effect was exacerbated in the presence of either l-NAME, nitroguandine, the guanylate cyclase inhibitor, ODQ, or the PKG inhibitor, KT5823, suggesting that NOS1-derived NO provides contractile support via a cGMP/PKG-dependent mechanism. Indeed, ODQ reduced Ca2+ wave velocity and both ODQ and KT5823 reduced the HS-induced increment in ryanodine receptor (RyR2, Ser2808) phosphorylation, suggesting that in this context, cGMP/PKG may contribute to preserve contractile function by enhancing sarcoplasmic reticulum Ca2+ release. Conclusions Our findings suggest a novel mechanism for NO release in cardiomyocytes with putative pathophysiological relevance determined, at least in part, by its capability to reduce the extent of contractile dysfunction associated with hypotonic swelling. PMID:25344365

Thermal insulation of pipelines by foamed glass-ceramic

NASA Astrophysics Data System (ADS)

Apkaryan, A. S.; Kudyakov, A. I.

2015-01-01

Based on broken glass, clay and organic additives granular insulating glass crystalline material and technology of its receipt are developed. The regularities of the effect of composition and firing temperature on the properties of the granules are specified. The resulting granular thermally insulating material is produced with a bulk density of 260-280 kg/m3 pellet strength - 1.74 MPa, thermal conductivity - 0.075 W/m °C, water absorption - 2.6 % by weight. The effect of the basic physical characteristics of the components of the charge on the process of pore formation is studied. According to the research results, basic parameters affecting the sustainability of the swelling glass are specified. Rational charge composition, thermal and gas synthesis mode are chosen so that the partial pressure of gases is below the surface tension of the melt. This enables the formation of granules with small closed pores and vitrified surface. The article is the result of studies on the application of materials for pipe insulation of heating mains with foamed glass ceramics.

Thoracic meningocele in lumbo-costo-vertebral syndrome in a child: possible enlargement with repeated motion by anchoring to the diaphragm.

PubMed

Wataya, Takafumi; Horikawa, Kyohei; Kitagawa, Masashi; Tashiro, Yuzuru

2016-08-01

Lumbo-costo-vertebral syndrome (LCVS) is a rare disorder in children that is characterized by hemivertebrae, congenital absence of ribs, meningocele, and hypoplasia of the truncal and abdominal wall presenting as a congenital lumbar hernia. An otherwise healthy 12-month-old girl was referred to the authors' hospital with soft swelling on her left middle back; scoliosis had been present since birth. Imaging revealed a thoracic meningocele, ectopia of the spleen suggesting lumbar hernia, multiple anomalies of the thoracic vertebral columns, and defects of the ribs; thus, LCVS was diagnosed. Surgical observation revealed that the meningocele was firmly anchored to part of the diaphragm, which created stretching tension in the meningocele continuously with exhalation. Once detached, the meningocele shrank spontaneously and never developed again after cauterization. In this case, continuous or pulsatile pressure in the presence of a vertebral defect was thus considered to be an important factor for formation of the thoracic meningocele.

Thermochemical and Physical Properties of Fluids, Lubricants and Related Materials. Delivery Order 0001 : Improved Methods Development for Determining Thermophysical and Thermochemical Properties of Fluids, Lubricants and Related Materials

DTIC Science & Technology

2008-07-01

PRF-5606H, ...................76 FTM 791C, method 36003) 168 hrs. @ 70ºC using NBR -L (AMS3217/2B Rubber specimens. 42. MLO-06...0275: Rubber Swell Test (MIL-PRF-5606H, .................77 FTM 791C, method 3603) 168 hrs. @ 70ºC using NBR -L...NUMBER MLO-05-421 Rubber Swell Test (MIL-PRF-5606H, FTM 791C, method 36003) 168 Hours @ 70°C (158°F) using NBR -L(AMS 3217/2B) rubber specimens

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

Gigax, Jonathan G.; Kim, Hyosim; Aydogan, Eda

Although accelerator-based ion irradiation has been widely accepted to simulate neutron damage, neutron-atypical features need to be carefully investigated. In this study, we have shown that Coulomb force drag by ion beams can introduce significant amounts of carbon, nitrogen, and oxygen into target materials even under ultra-high vacuum conditions. The resulting compositional and microstructural changes dramatically suppress void swelling. By applying a beam-filtering technique, introduction of vacuum contaminants is greatly minimized and the true swelling resistance of the alloys is revealed and matches neutron behavior closely. These findings are a significant step toward developing standardized procedures for emulating neutron damage.

Impact of grain size evolution on necking and pinch-and-swell formation in calcite layers

NASA Astrophysics Data System (ADS)

Schmalholz, Stefan Markus; Duretz, Thibault

2017-04-01

The formation of necking zones and the associated formation of pinch-and-swell structure is one form of strain localization in extending, competent layers. Natural pinch-and-swell structure in centimetre-thick calcite layers typically shows a reduction of grain size from swell towards pinch. However, the impact of grain size evolution on necking and pinch-and-swell formation is incompletely understood. We perform zero-dimensional (0D) and 2D thermo-mechanical numerical simulations to quantify the impact of grain size evolution on necking for extension rates between 10-12s^-1and10^-14 s-1 and temperatures around 350°C. For a combination of diffusion and dislocation creep we calculate grain size evolution according to the paleowattmeter (grain size is proportional to mechanical work rate) or the paleopiezometer (grain size is proportional to stress). Numerical results fit two observations: (i) grain size reduction from swells towards pinches, and (ii) dislocation creep dominated deformation in swells and significant contribution of diffusion creep in pinches. Modelled grain size in pinches (10 to 60 μm) and swells (70 to 800 μm) is close to observed grain size in pinches (15 to 27 μm) and in swells (250 to 1500 μm). Grain size evolution has only a minor impact on necking suggesting that grain size evolution is a consequence, and not the cause of necking. Viscous shear heating and grain size evolution had a negligible thermal impact in the simulations.

Atomistic simulation of laser-pulse surface modification: Predictions of models with various length and time scales

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

Starikov, Sergey V., E-mail: starikov@ihed.ras.ru; Pisarev, Vasily V.; Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow 125412

2015-04-07

In this work, the femtosecond laser pulse modification of surface is studied for aluminium (Al) and gold (Au) by use of two-temperature atomistic simulation. The results are obtained for various atomistic models with different scales: from pseudo-one-dimensional to full-scale three-dimensional simulation. The surface modification after laser irradiation can be caused by ablation and melting. For low energy laser pulses, the nanoscale ripples may be induced on a surface by melting without laser ablation. In this case, nanoscale changes of the surface are due to a splash of molten metal under temperature gradient. Laser ablation occurs at a higher pulse energymore » when a crater is formed on the surface. There are essential differences between Al ablation and Au ablation. In the first step of shock-wave induced ablation, swelling and void formation occur for both metals. However, the simulation of ablation in gold shows an additional athermal type of ablation that is associated with electron pressure relaxation. This type of ablation takes place at the surface layer, at a depth of several nanometers, and does not induce swelling.« less

Cold Spray Coating of Submicronic Ceramic Particles on Poly(vinyl alcohol) in Dry and Hydrogel States

NASA Astrophysics Data System (ADS)

Moreau, David; Borit, François; Corté, Laurent; Guipont, Vincent

2017-06-01

We report an approach using cold spray technology to coat poly(vinyl alcohol) (PVA) in polymer and hydrogel states with hydroxyapatite (HA). Using porous aggregated HA powder, we hypothesized that fragmentation of the powder upon cold spray could lead to formation of a ceramic coating on the surface of the PVA substrate. However, direct spraying of this powder led to complete destruction of the swollen PVA hydrogel substrate. As an alternative, HA coatings were successfully produced by spraying onto dry PVA substrates prior to swelling in water. Dense homogeneous HA coatings composed of submicron particles were obtained using rather low-energy spraying parameters (temperature 200-250 °C, pressure 1-3 MPa). Coated PVA substrates could swell in water without removal of the ceramic layer to form HA-coated hydrogels. Microscopic observations and in situ measurements were used to explain how local heating and impact of sprayed aggregates induced surface roughening and strong binding of HA particles to the molten PVA substrate. Such an approach could lead to design of ceramic coatings whose roughness and crystallinity can be finely adjusted to improve interfacing with biological tissues.

Functional materials for breeding blankets—status and developments

NASA Astrophysics Data System (ADS)

Konishi, S.; Enoeda, M.; Nakamichi, M.; Hoshino, T.; Ying, A.; Sharafat, S.; Smolentsev, S.

2017-09-01

The development of tritium breeder, neutron multiplier and flow channel insert materials for the breeding blanket of the DEMO reactor is reviewed. Present emphasis is on the ITER test blanket module (TBM); lithium metatitanate (Li2TiO3) and lithium orthosilicate (Li4SiO4) pebbles have been developed by leading TBM parties. Beryllium pebbles have been selected as the neutron multiplier. Good progress has been made in their fabrication; however, verification of the design by experiments is in the planning stage. Irradiation data are also limited, but the decrease in thermal conductivity of beryllium due to irradiation followed by swelling is a concern. Tests at ITER are regarded as a major milestone. For the DEMO reactor, improvement of the breeder has been attempted to obtain a higher lithium content, and Be12Ti and other beryllide intermetallic compounds that have superior chemical stability have been studied. LiPb eutectic has been considered as a DEMO blanket in the liquid breeder option and is used as a coolant to achieve a higher outlet temperature; a SiC flow channel insert is used to prevent magnetohydrodynamic pressure drop and corrosion. A significant technical gap between ITER TBM and DEMO is recognized, and the world fusion community is working on ITER TBM and DEMO blanket development in parallel.

Fractional cable equation for general geometry: A model of axons with swellings and anomalous diffusion.

PubMed

López-Sánchez, Erick J; Romero, Juan M; Yépez-Martínez, Huitzilin

2017-09-01

Different experimental studies have reported anomalous diffusion in brain tissues and notably this anomalous diffusion is expressed through fractional derivatives. Axons are important to understand neurodegenerative diseases such as multiple sclerosis, Alzheimer's disease, and Parkinson's disease. Indeed, abnormal accumulation of proteins and organelles in axons is a hallmark of these diseases. The diffusion in the axons can become anomalous as a result of this abnormality. In this case the voltage propagation in axons is affected. Another hallmark of different neurodegenerative diseases is given by discrete swellings along the axon. In order to model the voltage propagation in axons with anomalous diffusion and swellings, in this paper we propose a fractional cable equation for a general geometry. This generalized equation depends on fractional parameters and geometric quantities such as the curvature and torsion of the cable. For a cable with a constant radius we show that the voltage decreases when the fractional effect increases. In cables with swellings we find that when the fractional effect or the swelling radius increases, the voltage decreases. Similar behavior is obtained when the number of swellings and the fractional effect increase. Moreover, we find that when the radius swelling (or the number of swellings) and the fractional effect increase at the same time, the voltage dramatically decreases.

Nanosize effect of clay mineral nanoparticles on the drug diffusion processes in polyurethane nanocomposite hydrogels

NASA Astrophysics Data System (ADS)

Miotke, M.; Strankowska, J.; Kwela, J.; Strankowski, M.; Piszczyk, Ł.; Józefowicz, M.; Gazda, M.

2017-09-01

Studies of swelling and release of naproxen sodium (NAP) solution by polyurethane nanocomposite hydrogels containing Cloisite® 30B (organically modified montmorillonite (OMMT)) have been performed. Polyurethane nanocomposite hydrogels are hybrid, nontoxic biomaterials with unique swelling and release properties in comparison with unmodified hydrogels. These features enable to use nanocomposite hydrogels as a modern wound dressing. The presence of nanoparticles significantly improves the swelling. On the other hand, their presence hinders drug diffusion from polymer matrix and consequently causes delay of the drug release. The kinetics of swelling and release were carefully analyzed using the Korsmeyer-Peppas and the modified Hopfenberg models. The models were fitted to precise experimental data allowing accurate quantitative and qualitative analysis. We observed that 0.5% admixture of nanoparticles (Cloisite® 30B) is the best concentration for hydrogel swelling properties. The release process was studied using fluorescence excitation spectra of NAP. Furthermore, we studied swelling hysteresis; polymer chains have not been destroyed after the swelling and part of swelled solution with active substances which remained absorbed in the polymer matrix after the drying process. We have found that the amount of solution with NAP remained in the nanocomposite matrix is greater than in pure hydrogel, as a consequence of NAP-OMMT interactions (nanosize effect).

Fractional cable equation for general geometry: A model of axons with swellings and anomalous diffusion

NASA Astrophysics Data System (ADS)

López-Sánchez, Erick J.; Romero, Juan M.; Yépez-Martínez, Huitzilin

2017-09-01

Different experimental studies have reported anomalous diffusion in brain tissues and notably this anomalous diffusion is expressed through fractional derivatives. Axons are important to understand neurodegenerative diseases such as multiple sclerosis, Alzheimer's disease, and Parkinson's disease. Indeed, abnormal accumulation of proteins and organelles in axons is a hallmark of these diseases. The diffusion in the axons can become anomalous as a result of this abnormality. In this case the voltage propagation in axons is affected. Another hallmark of different neurodegenerative diseases is given by discrete swellings along the axon. In order to model the voltage propagation in axons with anomalous diffusion and swellings, in this paper we propose a fractional cable equation for a general geometry. This generalized equation depends on fractional parameters and geometric quantities such as the curvature and torsion of the cable. For a cable with a constant radius we show that the voltage decreases when the fractional effect increases. In cables with swellings we find that when the fractional effect or the swelling radius increases, the voltage decreases. Similar behavior is obtained when the number of swellings and the fractional effect increase. Moreover, we find that when the radius swelling (or the number of swellings) and the fractional effect increase at the same time, the voltage dramatically decreases.

Ocular Inserts for Sustained Release of the Angiotensin-Converting Enzyme 2 Activator, Diminazene Aceturate, to Treat Glaucoma in Rats

PubMed Central

Nogueira, José Carlos; Fulgêncio, Gustavo de Oliveira; Ribeiro, Tatiana Gomes; Castilho, Rachel Oliveira; Yoshida, Maria Irene; Fuscaldi, Leonardo Lima; Fernandes, Simone Odília Antunes; Cardoso, Valbert Nascimento; Cronemberger, Sebastião; Faraco, André Augusto Gomes; Ferreira, Anderson José

2015-01-01

The aim of this study was to develop and evaluate the effects of chitosan inserts for sustained release of the angiotensin-converting enzyme 2 (ACE2) activator, diminazene aceturate (DIZE), in experimental glaucoma. Monolayer DIZE loaded inserts (D+I) were prepared and characterized through swelling, attenuated total reflectance Fourier transformed infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC) and in vitro drug release. Functionally, the effects of D+I were tested in glaucomatous rats. Glaucoma was induced by weekly injections of hyaluronic acid (HA) into the anterior chamber and intraocular pressure (IOP) measurements were performed. Retinal ganglion cells (RGC) and optic nerve head cupping were evaluated in histological sections. Biodistribution of the drug was accessed by scintigraphic images and ex vivo radiation counting. We found that DIZE increased the swelling index of the inserts. Also, it was molecularly dispersed and interspersed in the polymeric matrix as a freebase. DIZE did not lose its chemical integrity and activity when loaded in the inserts. The functional evaluation demonstrated that D+I decreased the IOP and maintained the IOP lowered for up to one month (last week: 11.0±0.7 mmHg). This effect of D+I prevented the loss of RGC and degeneration of the optic nerve. No toxic effects in the eyes related to application of the inserts were observed. Moreover, biodistribution studies showed that D+I prolonged the retention of DIZE in the corneal site. We concluded that D+I provided sustained DIZE delivery in vivo, thereby evidencing the potential application of polymeric-based DIZE inserts for glaucoma management. PMID:26204514

Novel biodegradable hydrogel sponge containing curcumin and honey for wound healing.

PubMed

Momin, M; Kurhade, S; Khanekar, P; Mhatre, S

2016-06-01

To develop and evaluate a biodegradable superporous hydrogel based wound healing composite of chitosan and alginate incorporated with curcumin and honey. A 3(2) factorial design was adopted to optimise the honey-curcumin hydrogel composite sponge (CHS). Sodium alginate and chitosan were dissolved in deionised water and 1% aqueous acetic acid solution at room temperature, respectively. Ethanolic solution of curcumin was poured into the chitosan solution followed by an addition of sodium alginate solution. In situ polymerisation was carried out by adding acrylamide base components to the polymeric solution of curcumin. Finally, honey was added with slow stirring and a sponge was cast on a glass surface by solvent evaporation at 45ºC. The produced sponge was assessed for swelling capacity, moisture loss, tensile strength, biocompatibility, bioadhesion, biodegradation, drug diffusion and wound healing properties. The morphology of CHS was studied by scanning electron microscopy (SEM). The optimised CHS demonstrated a high swelling capacity (111.05 ± 05%), tensile strength (4323gm/mm(2)), in vitro drug diffusion (75.03 ± 3.59%/20days), bioadhesion (20 ± 0.2mg force) and ability of water vapour transmission. A rapid induction of tissue granulation and re-epithelialisation was observed. Time to complete healing (94.14 ± 1.04% wound contraction) was 7 ± 2 days. This study has shown that honey-curcumin hydrogel composite sponge can be formulated by a simple mixing and in situ polymerisation method. The hydrogel base provided a dry wound bed due to excellent fluid absorption capacity. Chitosan and honey contributed to effective faster wound healing. We recommend further clinical studies of the soft sponge wound healing composite for diabetic foot or pressure ulcers.

A study on the swelling behavior of poly(acrylic acid) hydrogels obtained by electron beam crosslinking

NASA Astrophysics Data System (ADS)

Sheikh, N.; Jalili, L.; Anvari, F.

2010-06-01

Poly(acrylic acid) (PAA) hydrogels were prepared by using electron beam (EB) crosslinking of PAA homopolymer from its aqueous solutions. The swelling behavior of the hydrogels was studied as a function of the concentration of PAA solution, radiation dose, pH of the swelling medium and swelling time. Also the environmental pH effect on the water diffusion mode into hydrogels was investigated. These hydrogels clearly showed pH-sensitive swelling behavior with Fickian type of diffusion in the stomach-like pH medium (pH 1.3) and non-Fickian type in the intestine-like pH medium (pH 6.8).

Wave Dissipation on Low- to Super-Energy Coral Reefs

NASA Astrophysics Data System (ADS)

Harris, D. L.

2016-02-01

Coral reefs are valuable, complex and bio-diverse ecosystems and are also known to be one of the most effective barriers to swell events in coastal environments. Previous research has found coral reefs to be remarkably efficient in removing most of the wave energy during the initial breaking and transformation on the reef flats. The rate of dissipation is so rapid that coral reefs have been referred to as rougher than any known coastal barrier. The dissipation of wave energy across reef flats is crucial in maintaining the relatively low-energy conditions in the back reef and lagoonal environments providing vital protection to adjacent beach or coastal regions from cyclone and storm events. A shift in the regulation of wave energy by reef flats could have catastrophic consequences ecologically, socially, and economically. This study examined the dissipation of wave energy during two swell events in Tahiti and Moorea, French Polyesia. Field sites were chosen in varying degrees of exposure and geomorphology from low-energy protected sites (Tiahura, Moorea) to super-energy sites (Teahupo'o, Tahiti). Waves were measured during two moderate to large swell events in cross reef transects using short-term high-resolution pressure transducers. Wave conditions were found to be similar in all back reef locations despite the very different wave exposure at each reef site. However, wave conditions on the reef flats were different and mirrored the variation in wave exposure with depth over the reef flat the primary regulator of reef flat wave height. These results indicate that coral reef flats evolve morphodynamically with the wave climate, which creates coral reef geomorphologies capable of dissipating wave energy that results in similar back reef wave conditions regardless of the offshore wave climate.

Hygroscopic Swelling Determination of Cellulose Nanocrystal (CNC) Films by Polarized Light Microscopy Digital Image Correlation.

PubMed

Shrestha, Shikha; Diaz, Jairo A; Ghanbari, Siavash; Youngblood, Jeffrey P

2017-05-08

The coefficient of hygroscopic swelling (CHS) of self-organized and shear-oriented cellulose nanocrystal (CNC) films was determined by capturing hygroscopic strains produced as result of isothermal water vapor intake in equilibrium. Contrast enhanced microscopy digital image correlation enabled the characterization of dimensional changes induced by the hygroscopic swelling of the films. The distinct microstructure and birefringence of CNC films served in exploring the in-plane hygroscopic swelling at relative humidity values ranging from 0% to 97%. Water vapor intake in CNC films was measured using dynamic vapor sorption (DVS) at constant temperature. The obtained experimental moisture sorption and kinetic profiles were analyzed by fitting with Guggenheim, Anderson, and deBoer (GAB) and Parallel Exponential Kinetics (PEK) models, respectively. Self-organized CNC films showed isotropic swelling, CHS ∼0.040 %strain/%C. By contrast, shear-oriented CNC films exhibited an anisotropic swelling, resulting in CHS ∼0.02 and ∼0.30 %strain/%C, parallel and perpendicular to CNC alignment, respectively. Finite element analysis (FEA) further predicted moisture diffusion as the predominant mechanism for swelling of CNC films.

Swelling-induced chloride current in glioblastoma proliferation, migration, and invasion.

PubMed

Wong, Raymond; Chen, Wenliang; Zhong, Xiao; Rutka, James T; Feng, Zhong-Ping; Sun, Hong-Shuo

2018-01-01

Glioblastoma (GBM) remains as the most common and aggressive brain tumor. The survival of GBM has been linked to the aberrant activation of swelling-induced chloride current I Cl,swell . In this study, we investigated the effects of I Cl,swell on cell viability, proliferation, and migration in the human GBM cell lines, U251 and U87, using a combination of patch clamp electrophysiology, MTT, colony formation, wound healing assays and Western immunoblotting. First, we showed that the specific inhibitor of I Cl,swell , DCPIB, potently reduced the I Cl,swell in U87 cells. Next, in both U87 and U251 cells, we found that DCPIB reduced GBM viability, proliferation, colony formation, migration, and invasion. In addition, our Western immunoblot assay showed that DCPIB-treated U251 cells had a reduction in JAK2, STAT3, and Akt phosphorylation, thus, suggesting that DCPIB potentially suppresses GBM functions through inhibition of the JAK2/STAT3 and PI3K/Akt signaling pathways. Therefore, the I Cl,swell may be a potential drug target for GBM. © 2017 Wiley Periodicals, Inc.

Kinetics of electrically and chemically induced swelling in polyelectrolyte gels

NASA Astrophysics Data System (ADS)

Grimshaw, P. E.; Nussbaum, J. H.; Grodzinsky, A. J.; Yarmush, M. L.

1990-09-01

Controlled swelling and shrinking of polyelectrolyte gels is useful for regulating the transport of solutes into, out of, and through these materials. A macroscopic continuum model is presented to predict the kinetics of swelling in polyelectrolyte gel membranes induced by augmentation of electrostatic swelling forces arising from membrane fixed charge groups. The model accounts for ionic transport within the membrane, electrodiffusion phenomena, dissociation of membrane charge groups, intramembrane fluid flow, and mechanical deformation of the membrane matrix. Model predictions are compared with measurements of chemically and electrically induced swelling and shrinking in crosslinked polymethacrylic acid (PMAA) membranes. Large, reversible changes in PMAA membrane hydration were observed after changing the bath pH or by applying an electric field to modify the intramembrane ionic environment and fixed charge density. A relatively slow swelling process and more rapid shrinking for both chemical and electrical modulation of the intramembrane pH are observed. The model indicates that retardation of membrane swelling is dominated by diffusion-limited reaction of H+ ions with membrane charge groups, and that the more rapid shrinking is limited primarily by mechanical processes.

Swelling of Superabsorbent Poly(Sodium-Acrylate Acrylamide) Hydrogels and Influence of Chemical Structure on Internally Cured Mortar

NASA Astrophysics Data System (ADS)

Krafcik, Matthew J.; Erk, Kendra A.

Superabsorbent hydrogel particles show promise as internal curing agents for high performance concrete (HPC). These gels can absorb and release large volumes of water and offer a solution to the problem of self-dessication in HPC. However, the gels are sensitive to ions naturally present in concrete. This research connects swelling behavior with gel-ion interactions to optimize hydrogel performance for internal curing, reducing the chance of early-age cracking and increasing the durability of HPC. Four different hydrogels of poly(sodium-acrylate acrylamide) are synthesized and characterized with swelling tests in different salt solutions. Depending on solution pH, ionic character, and gel composition, diffrerent swelling behaviors are observed. As weight percent of acrylic acid increases, gels demonstrate higher swelling ratios in reverse osmosis water, but showed substantially decreased swelling when aqueous cations are present. Additionally, in multivalent cation solutions, overshoot peaks are present, whereby the gels have a peak swelling ratio but then deswell. Multivalent cations interact with deprotonated carboxylic acid groups, constricting the gel and expelling water. Mortar containing hydrogels showed reduced autogenous shrinkage and increased relative humidity.

Intramuscular pressures for monitoring different tasks and muscle conditions

NASA Technical Reports Server (NTRS)

Sejersted, O. M.; Hargens, A. R.

1995-01-01

Intramuscular fluid pressure (IMP) can easily be measured in man and animals. It follows the law of Laplace which means that it is determined by the tension of the muscle fibers, the recording depth and by fiber geometry (fiber curvature or pennation angle). Thick, bulging muscles create high IMPs (up to 1000 mmHg) and force transmission to tendons becomes inefficient. High resting or postexercise IMPs are indicative of a compartment syndrome due to muscle swelling within a low-compliance osseofascial boundary. IMP increases linearly with force (torque) independent of the mode or speed of contraction (isometric, eccentric, concentric). IMP is also a much better predictor of muscle force than the EMG signal. During prolonged low-force isometric contractions, cyclic variations in IMP are seen. Since IMP influences muscle blood flow through the muscle pump, autoregulating vascular elements, and compression of the intramuscular vasculature, alterations in IMP have important implications for muscle function.

Seafloor doming driven by degassing processes unveils sprouting volcanism in coastal areas.

PubMed

Passaro, Salvatore; Tamburrino, Stella; Vallefuoco, Mattia; Tassi, Franco; Vaselli, Orlando; Giannini, Luciano; Chiodini, Giovanni; Caliro, Stefano; Sacchi, Marco; Rizzo, Andrea Luca; Ventura, Guido

2016-03-01

We report evidences of active seabed doming and gas discharge few kilometers offshore from the Naples harbor (Italy). Pockmarks, mounds, and craters characterize the seabed. These morphologies represent the top of shallow crustal structures including pagodas, faults and folds affecting the present-day seabed. They record upraise, pressurization, and release of He and CO2 from mantle melts and decarbonation reactions of crustal rocks. These gases are likely similar to those that feed the hydrothermal systems of the Ischia, Campi Flegrei and Somma-Vesuvius active volcanoes, suggesting the occurrence of a mantle source variously mixed to crustal fluids beneath the Gulf of Naples. The seafloor swelling and breaching by gas upraising and pressurization processes require overpressures in the order of 2-3 MPa. Seabed doming, faulting, and gas discharge are manifestations of non-volcanic unrests potentially preluding submarine eruptions and/or hydrothermal explosions.

Seafloor doming driven by degassing processes unveils sprouting volcanism in coastal areas

PubMed Central

Passaro, Salvatore; Tamburrino, Stella; Vallefuoco, Mattia; Tassi, Franco; Vaselli, Orlando; Giannini, Luciano; Chiodini, Giovanni; Caliro, Stefano; Sacchi, Marco; Rizzo, Andrea Luca; Ventura, Guido

2016-01-01

We report evidences of active seabed doming and gas discharge few kilometers offshore from the Naples harbor (Italy). Pockmarks, mounds, and craters characterize the seabed. These morphologies represent the top of shallow crustal structures including pagodas, faults and folds affecting the present-day seabed. They record upraise, pressurization, and release of He and CO2 from mantle melts and decarbonation reactions of crustal rocks. These gases are likely similar to those that feed the hydrothermal systems of the Ischia, Campi Flegrei and Somma-Vesuvius active volcanoes, suggesting the occurrence of a mantle source variously mixed to crustal fluids beneath the Gulf of Naples. The seafloor swelling and breaching by gas upraising and pressurization processes require overpressures in the order of 2–3 MPa. Seabed doming, faulting, and gas discharge are manifestations of non-volcanic unrests potentially preluding submarine eruptions and/or hydrothermal explosions. PMID:26925957

Effect of dynamic high pressure on technological properties of cashew tree gum (Anacardium occidentale L.).

PubMed

Porto, Bruna Castro; Augusto, Pedro E D; Terekhov, Anton; Hamaker, Bruce R; Cristianini, Marcelo

2015-09-20

Dynamic high pressure (DHP) appears to be an alternative approach to physical modification of polysaccharides aimed improving their technological properties. Therefore, its effect on the functional properties of polysaccharides (i.e., oil absorption capacity, emulsifier, and rheology) needs to be investigated. Cashew tree gum (CG) is a biological macromolecule that has been proposed to be used as an emulsifier in beverage emulsions. To the best of our knowledge, none of the articles in the literature investigates the effect of DHP on the CG properties. This work presents a study on the evaluation of the effects of DHP on functional characteristics of CG, including rheological properties, molecular weight, glycosyl-linkage analysis, solubility, swelling and oil absorption capacity (OAC). The results suggest that DHP is able to modify the technological properties of cashew tree gum (increasing solubility and decreasing apparent viscosity). Copyright © 2015 Elsevier Ltd. All rights reserved.

ELASTICITY, DOUBLE REFRACTION AND SWELLING OF ISOELECTRIC GELATIN

PubMed Central

Kunitz, M.

1930-01-01

Quincke's researches (1904) have demonstrated that when a 20 per cent gelatin gel is allowed to swell in water it gives rise to positive double refraction, as if the gel were under tensile stresses. If, on the other hand, the gel shrinks on being placed in alcohol it becomes negatively double refractive, as if it were compressed. But the double refraction as found by Quincke lasts only during the process of swelling or shrinking, and disappears as soon as the gel reaches a state of equilibrium. This phenomenon was investigated here and it was found that the reason for the disappearance of the double refraction is due to the fact that at equilibrium the percentage change in the size of a gel is equal in all three dimensions and the strain is therefore uniform. Double refraction persists as long as there is a difference in the elastic strain in the three dimensions of the strained material. It was found that when gels are cast on glass slides or in glass frames, so as to prevent swelling in certain directions, the double refraction produced by swelling at 6°C. persists permanently in the gel as long as it is swollen, and is proportional to the percentage change in the linear dimensions of the gel. Gels made up of various concentrations of isoelectric gelatin of less than 10 per cent when placed in dilute buffer of the same pH as that of the isoelectric point of the gelatin shrink and give rise to negative double refraction, while gels of concentrations of more than 10 per cent swell and give rise to positive double refraction. The double refraction produced in either case when divided by the percentage change in the dimensions of the gel and by its changed concentration gives a constant value both for swelling and shrinking. This constant which stands for the double refraction produced in a gel of unit concentration per unit strain is termed here the optical modulus of elasticity since it is proportional to the internal elastic stress in the swollen gelatin. It was found that the optical modulus of elasticity is the same both for gels cast on slides and in frames, although the mode of swelling is different in the two forms of gels. Gels removed from their glass supports after apparent swelling equilibrium, when placed in dilute buffer, begin to swell gradually in all three dimensions and the double refraction decreases slowly, though it persists for a long time. But the double refraction per unit change in dimension and per unit concentration still remains the same as before, thus proving that the internal elastic stress as indicated by the double refraction is brought about by the resistance of the gel itself to deformation. A study was also made on the effect of salts, acid and base on the double refraction of a 10 per cent gel during swelling. The experiments show that below M/8 salts affect very slightly the optical modulus of elasticity of the gel. At higher concentrations of salts the elasticity of the gel is reduced by some salts and increased by others, while such salts as sodium acetate and sodium and ammonium sulfates do not change the elasticity of the gels at all during swelling. The investigated salts may thus be arranged in this respect in the following approximate series: CaCl2, NaI, NaSCN, NaBr, AlCl3, NaCl, Na acetate, Na2SO4, (NH4)2SO4, Al2SO4 and MgSO4. The first five in the series decrease the elasticity while the last two in the series increase the elasticity of the gels during swelling. Acids and bases in higher concentrations exert a powerful influence on the reduction of the elasticity of the gel but in the range of pH between 2.0 and 10.0 the elasticity remains unaffected. The general conclusions to be drawn from these studies are as follows: 1. Swelling or shrinking produces elastic stresses in gels of gelatin, tensile in the first case and compressive in the second case, both being proportional to the percentage change in the dimensions of the gel. 2. Unsupported gels when immersed in aqueous solutions swell or shrink in such a manner that at equilibrium the percentage change in size is equal in all three dimensions, and the stresses become equalized throughout the gel. 3. Gels cast on glass slides or in frames when immersed in aqueous solutions swell or shrink mostly in one direction, and give rise to unidirectional stresses that can be determined accurately by measuring the double refraction produced. 4. The modulus of elasticity of swelling gelatin gels, as calculated from the double refraction measurements, is the same both for compression and for tension and is proportional to the concentration of gelatin in the gel. 5. The modulus of elasticity of gels during swelling is affected only slightly or not at all by salts at concentrations of less than M/8 and is independent of the pH in the range approximately between 2.0 and 10.0. 6. Higher concentrations of salts affect the modulus of elasticity of gelatin gels and the salts in their effectiveness may be arranged in a series similar to the known Hoffmeister series. 7. Acid and alkali have a strong reducing influence on the elastic modulus of swelling gels. 8. The swelling produced in isoelectric gelatin by salts is due primarily to a change brought about by the salts in the osmotic forces in the gel, but in high concentrations of some salts the swelling is increased by the influence of the salt on the elasticity of the gel. This agrees completely with the theory of swelling of isoelectric gelatin as developed by Northrop and the writer in former publications. 9. The studies of Loeb and the writer on the effect of salts on swelling of gelatin in acid and alkali have been in the range of concentrations of salts where the modulus of elasticity of the gelatin is practically constant, and the specific effect of the various salts has been negligible as compared with the effect of the valency of the ions. In concentrations of salts below M/4 or M/8 the Hoffmeister series plays no rôle. PMID:19872548

Through the looking glass: Unraveling the network structure of coal

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

Gregory, D. M.; Stec, D. F.; Botto, R. E.

1999-12-23

Since the original idea by Sanada and Honda of treating coal as a three-dimensional cross-linked network, coal structure has been probed by monitoring ingress of solvents using traditional volumetric or gravimetric methods. However, using these techniques has allowed only an indirect observation of the swelling process. More recently, the authors have developed magnetic resonance microscopy (MRM) approaches for studying solvent ingress in polymeric systems, about which fundamental aspects of the swelling process can be deduced directly and quantitatively. The aim of their work is to utilize solvent transport and network response parameters obtained from these methods to assess fundamental propertiesmore » of the system under investigation. Polymer and coal samples have been studied to date. Numerous swelling parameters measured by magnetic resonance microscopy are found to correlate with cross-link density of the polymer network under investigation. Use of these parameters to assess the three-dimensional network structure of coal is discussed.« less

Development of smart delivery system for ascorbic acid using pH-responsive P(MAA-co-EGMA) hydrogel microparticles.

PubMed

Lee, Eunmi; Kim, Kyusik; Choi, Moonjae; Lee, Youngmoo; Park, Jin-Won; Kim, Bumsang

2010-11-01

pH-Responsive P(MAA-co-EGMA) hydrogel microparticles were prepared and their feasibility as intelligent delivery carriers was evaluated. P(MAA-co-EGMA) hydrogel microparticles were synthesized via dispersion photopolymerization. There was a drastic change in the swelling ratio of P(MAA-co-EGMA) microparticles at a pH of ~ 5 and, as the amount of MAA in the hydrogel increased, the swelling ratio increased at a pH above 5. The loading efficiency of the ascorbic acid into the hydrogel was affected more by the degree of swelling of the hydrogel than the electrostatic interaction between the hydrogel and the loaded ascorbic acid. The P(MAA-co-EGMA) hydrogel microparticles showed a pH-sensitive release behavior. Thus, at pH 4 almost none of the ascorbic acid permeated through the skin while at pH 6 relatively high skin permeability was obtained. The ascorbic acid loaded in the hydrogel particles was hardly degraded and its stability was maintained at high temperature.

Design of radiation resistant metallic multilayers for advanced nuclear systems

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

Zhernenkov, Mikhail, E-mail: zherne@bnl.gov, E-mail: gills@bnl.gov; Gill, Simerjeet, E-mail: zherne@bnl.gov, E-mail: gills@bnl.gov; Stanic, Vesna

2014-06-16

Helium implantation from transmutation reactions is a major cause of embrittlement and dimensional instability of structural components in nuclear energy systems. Development of novel materials with improved radiation resistance, which is of the utmost importance for progress in nuclear energy, requires guidelines to arrive at favorable parameters more efficiently. Here, we present a methodology that can be used for the design of radiation tolerant materials. We used synchrotron X-ray reflectivity to nondestructively study radiation effects at buried interfaces and measure swelling induced by He implantation in Cu/Nb multilayers. The results, supported by transmission electron microscopy, show a direct correlation betweenmore » reduced swelling in nanoscale multilayers and increased interface area per unit volume, consistent with helium storage in Cu/Nb interfaces in forms that minimize dimensional changes. In addition, for Cu/Nb layers, a linear relationship is demonstrated between the measured depth-dependent swelling and implanted He density from simulations, making the reflectivity technique a powerful tool for heuristic material design.« less

Effects of an alveolar recruitment maneuver on subdural pressure, brain swelling, and mean arterial pressure in patients undergoing supratentorial tumour resection: a randomized crossover study.

PubMed

Flexman, Alana M; Gooderham, Peter A; Griesdale, Donald E; Argue, Ruth; Toyota, Brian

2017-06-01

Although recruitment maneuvers have been advocated as part of a lung protective ventilation strategy, their effects on cerebral physiology during elective neurosurgery are unknown. Our objectives were to determine the effects of an alveolar recruitment maneuver on subdural pressure (SDP), brain relaxation score (BRS), and cerebral perfusion pressure among patients undergoing supratentorial tumour resection. In this prospective crossover study, patients scheduled for resection of a supratentorial brain tumour were randomized to undergo either a recruitment maneuver (30 cm of water for 30 sec) or a "sham" maneuver (5 cm of water for 30 sec), followed by the alternative intervention after a 90-sec equilibration period. Subdural pressure was measured through a dural perforation following opening of the cranium. Subdural pressure and mean arterial pressure (MAP) were recorded continuously. The blinded neurosurgeon provided a BRS at baseline and at the end of each intervention. During each treatment, the changes in SDP, BRS, and MAP were compared. Twenty-one patients underwent the study procedure. The increase in SDP was higher during the recruitment maneuver than during the sham maneuver (difference, 3.9 mmHg; 95% confidence interval [CI], 2.2 to 5.6; P < 0.001). Mean arterial pressure decreased further in the recruitment maneuver than in the sham maneuver (difference, -9.0 mmHg; 95% CI, -12.5 to -5.6; P < 0.001). Cerebral perfusion pressure decreased 14 mmHg (95% CI, 4 to 24) during the recruitment maneuver. The BRS did not change with either maneuver. Our results suggest that recruitment maneuvers increase subdural pressure and reduce cerebral perfusion pressure, although the clinical importance of these findings is thus far unknown. This trial was registered with ClinicalTrials.gov, NCT02093117.

Side Effects: Edema (Swelling)

Cancer.gov

Edema is a condition in which fluid builds up in your body’s tissues. The swelling may be caused by chemotherapy, cancer, and conditions not related to cancer. Learn about signs of edema, including swelling in your feet, ankles, and legs.

Application of pinch-and-swell structure rheology gauge to determine rock paleo-rheological parameters in Taili, western Liaoning, NE China

NASA Astrophysics Data System (ADS)

Sun, Zhengquan; Zeng, Zuoxun; Wu, Linbo; Xu, Shaopeng; Yang, Shuang; Chen, Deli; Wang, Jianxiu

2017-05-01

New results, in combination with previously published ones, reveal that when the Stress Exponent of the Competent layer (SEC) ranges from 1 to 10 (1 < n < 10), Pinch-and-Swell structure Rheology Gauge (PSRG) can only be available under the condition that the Viscosity ratio between the Competent layer and its corresponding Matrix layer (VCM) is larger than 10. Therefore, we made the attempt to calculate the viscosity ratio of pinch-and-swell structure of competent layer to the related matrix and stress exponent. Based on this knowledge, we applied this gauge to calculate SECs and VCMs of eight types of pinch-and-swell structures, which are widely developed in the Taili area of the west Liaoning Province in China. Statistical analysis of the SEC resulted in intervals of four types of competent layers, that is, Medium-scale Granitic coarse-to-pegmatitic Veins, Small-scale Augen Granite aplite Veins, Small-scale Granite aplite Veins, and Small-scale Augen Quartz-K-feldspar veins, with intervals of [3.50, 4.63], [2.64, 4.29], [2.70, 3.51], and [2.50, 3.36] respectively. The preferred intervals of VCM of the five types of pinch-and-swell structures, Small-scale Augen Granite aplite Veins + Fine-grained Biotite-Hornblende-plagioclase Gneiss, Medium-scale Granitic coarse-to-pegmatitic Veins + Fine-grained Biotite-Hornblende-plagioclase Gneiss, Small-scale Augen Granite aplite Veins + medium-to-fine-grained granitic gneiss, Medium-scale Granitic coarse-to-pegmatitic Veins + medium-to-fine-grained granitic gneiss, and Small-scale Augen Granite aplite Veins + fine-grained biotite-plagioclase gneiss, are [19.98, 62.51], [15.90, 61.17], [26.72, 93.27], [22.21, 107.26], and [76.33, 309.39] respectively. The similarities between these calculated SEC statistical preferred intervals and the physical experimental results verify the validity of the PSRG. The competent layers of the pinch-and-swell structures were presented in this study as power-law flow with SEC values that increased with the thickness of the layer. Grain-size plays an important role in the rheology of pinch-and-swell structures. The results offer a case for the application of PSRG and determine the key rock rheological parameters of North China Craton for future related studies.

A volatile tracer-assisted headspace analytical technique for determining the swelling capacity of superabsorbent polymers.

PubMed

Zhang, Shu-Xin; Jiang, Ran; Chai, Xin-Sheng

2017-09-01

This paper reports on a new method for the determination of swelling capacity of superabsorbent polymers by a volatile tracer-assisted headspace gas chromatography (HS-GC). Toluene was used as a tracer and added to the solution for polymers swelling test. Based on the differences of the tracer partitioned between the vapor and hydrogel phase before and after the polymer's swelling capacity, a transition point (corresponding to the material swelling capacity) can be observed when plotting the GC signal of toluene vs. the ratio of solution added to polymers. The present method has good precision (RSD<2.1%) and good accuracy, in which the relative deference between the data measured by the HS-GC method and the reference method were within 8.0%. The present method is very suitable to be used for testing the swelling capacity of polymers at the elevated temperatures. Copyright © 2017 Elsevier B.V. All rights reserved.

Optimizing membrane electrode assembly of direct methanol fuel cells for portable power

NASA Astrophysics Data System (ADS)

Liu, Fuqiang

Direct methanol fuel cells (DMFCs) for portable power applications require high power density, high-energy conversion efficiency and compactness. These requirements translate to fundamental properties of high methanol oxidation and oxygen reduction kinetics, as well as low methanol and water crossover. In this thesis a novel membrane electrode assembly (MEA) for direct methanol fuel cells has been developed, aiming to improve these fundamental properties. Firstly, methanol oxidation kinetics has been enhanced and methanol crossover has been minimized by proper control of ionomer crystallinity and its swelling in the anode catalyst layer through heat-treatment. Heat-treatment has a major impact on anode characteristics. The short-cured anode has low ionomer crystallinity, and thus swells easily when in contact with methanol solution to create a much denser anode structure, giving rise to higher methanol transport resistance than the long-cured anode. Variations in interfacial properties in the anode catalyst layer (CL) during cell conditioning were also characterized, and enhanced kinetics of methanol oxidation and severe limiting current phenomenon were found to be caused by a combination of interfacial property variations and swelling of ionomer over time. Secondly, much effort has been expended to develop a cathode CL suitable for operation under low air stoichiometry. The effects of fabrication procedure, ionomer content, and porosity distribution on the microstructure and cathode performance under low air stoichiometry are investigated using electrochemical and surface morphology characterizations to reveal the correlation between microstructure and electrochemical behavior. At the same time, computational fluid dynamics (CFD) models of DMFC cathodes have been developed to theoretically interpret the experimental results, to investigate two-phase transport, and to elucidate mechanism of cathode mixed potential due to methanol crossover. Thirdly, a MEA with low water crossover has been developed by employing a highly-hydrophobic microporous layer (MPL) to build up hydraulic pressure at the cathode, promoting product water permeation from the cathode to anode to offset water dragged by electro-osmosis. Water crossover through the MEA is further reduced by an anode hydrophobic MPL through facilitating water back diffusion. Under different current densities, the MEA with hydrophobic MPL has consistently low alpha, several times smaller than those with hydrophilic or without MPL. A simulation study of anode water transport by a two-phase model shows that anode MPL wettability strongly determines liquid saturation in the anode, and thus is identified as playing a crucial role in promoting water back diffusion. Finally, direct feed of highly-concentrated methanol using the optimized MEA has been successfully demonstrated by a face-feed anode plate, which minimizes methanol crossover by controlling the fuel delivery rate. Using 10 M methanol, a steady-state power density of ˜67mW/cm2 is reached at 60°C and 175mA/cm2, which is almost identical to that with 2M methanol.

Evaluation of a novel delayed-type hypersensitivity assay to Candida albicans in adult and neonatal rats.

PubMed

Thorn, Mitchell; Hudson, Adam W; Kreeger, John; Kawabe, Thomas T; Bowman, Christopher J; Collinge, Mark

2015-01-01

Delayed-type hypersensitivity (DTH) is a T-cell-mediated immune response that may be used for immunotoxicity testing in non-clinical species. However, in some cases DTH assays using T-dependent antigens may be confounded by the production of antibodies to the antigen. The authors have previously modified a DTH assay, initially validated in the mouse, for use in juvenile rats to assess the effect of immunosuppressive drugs on the developing rat immune system. The assay measures footpad swelling induced by subcutaneous footpad injection of Candida albicans (C. albicans) derived-chitosan in rats previously sensitized with C. albicans. Antibodies to chitosan are not produced in this model. However, considerable inter-animal variability inherent in the footpad swelling assay can make it difficult to precisely quantify the magnitude of the immune response and inhibition by immunosuppressants, particularly if complete suppression is not observed. This report describes the development of an ex vivo assay to assess DTH in rats using interferon (IFN)-γ production by splenocytes, obtained from rats sensitized with C. albicans, as the quantifiable measure of the DTH response. Adult and neonatal rats administered dexamethasone (DEX), a known immunosuppressant, exhibited immunosuppression as evidenced by a reduction in ex vivo IFNγ production from splenocytes challenged with C. albicans-derived chitosan. Current data indicate that the ex vivo based DTH assay is more sensitive than the conventional footpad swelling assay due to a lower background response and the ability to detect a response as early as post-natal day (PND) 12. The ex vivo based rat DTH assay offers a highly sensitive and quantitative alternative to the footpad swelling assay for the assessment of the immunotoxic potential of drugs. The increased sensitivity of the ex vivo DTH assay may be useful for identifying smaller changes in response to immunotoxic drugs, as well as detecting responses earlier in animal development.

HIV/AIDS

MedlinePlus

... on the phase of infection. Primary infection (Acute HIV) Most people infected by HIV develop a flu- ... during the next stage. Clinical latent infection (Chronic HIV) In some people, persistent swelling of lymph nodes ...

A new approach combining different MRI methods to provide detailed view on swelling dynamics of xanthan tablets influencing drug release at different pH and ionic strength.

PubMed

Mikac, Ursa; Sepe, Ana; Kristl, Julijana; Baumgartner, Sasa

2010-08-03

The key element in drug release from hydrophilic matrix tablets is the gel layer that regulates the penetration of water and controls drug dissolution and diffusion. We have selected magnetic resonance imaging (MRI) as the method of choice for visualizing the dynamic processes occurring during the swelling of xanthan tablets in a variety of media. The aims were (i) to develop a new method using MRI for accurate determination of penetration, swelling and erosion fronts, (ii) to investigate the effects of pH and ionic strength on swelling, and (iii) to study the influence of structural changes in xanthan gel on drug release. Two dimensional (2D) MRI and one dimensional single point imaging (SPI) of swollen xanthan tablets were recorded, together with T(2) mapping. The border between dry and hydrated glassy xanthan-the penetration front-was determined from 1D SPI signal intensity profiles. The erosion front was obtained from signal intensity profiles of 2D MR images. The swelling front, where xanthan is transformed from a glassy to a rubbery state (gel formation), was determined from T(2) profiles. Further, the new combination of MRI methods for swelling front determination enables to explain the appearance of the unusual "bright front" observed on 2D MR images in tablets swollen in HCl pH 1.2 media, which represents the position of swelling front. All six media studied, differing in pH and ionic strength, penetrate through the whole tablet in 4h+/-0.3h, but formation of the gel layer is significantly delayed. Unexpectedly, the position of the swelling front was the same, independently of the different xanthan gel structures formed under different conditions of pH and ionic strength. The position of the erosion front, on the other hand, is strongly dependent on pH and ionic strength, as reflected in different thicknesses of the gel layers. The latter are seen to be the consequence of the different hydrodynamic radii of the xanthan molecules, which affect the drug release kinetics. The slowest release of pentoxifylline was observed in water where the thickest gel was formed, whereas the fastest release was observed in HCl pH 1.2, in which the gel layer was thinnest. Moreover, experiments simulating physiological conditions showed that changes of pH and ionic strength influence the xanthan gel structure relatively quickly, and consequently the drug release kinetics. It is therefore concluded that drug release is greatly influenced by changes in the xanthan molecular conformation, as reflected in changed thickness of the gel layer. A new method utilizing combination of SPI, multi-echo MRI and T(2) mapping eliminates the limitations of standard methods used in previous studies for determining moving fronts and improves current understanding of the dynamic processes involved in polymer swelling. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Ischemia-induced endothelial cell swelling and mitochondrial dysfunction are attenuated by cinnamtannin D1, green tea extract, and resveratrol in vitro.

PubMed

Panickar, Kiran S; Qin, Bolin; Anderson, Richard A

2015-10-01

Polyphenols possess antioxidant and anti-inflammatory properties. Oxidative stress (OS) and inflammation have been implicated in the pathogenesis of cytotoxic brain edema in cerebral ischemia. In addition, OS and pro-inflammatory cytokines also damage the endothelial cells and the neurovascular unit. Endothelial cell swelling may contribute to a leaky blood-brain barrier which may result in vasogenic edema in the continued presence of the existing cytotoxic edema. We investigated the protective effects of polyphenols on cytotoxic cell swelling in bEND3 endothelial cultures subjected to 5 hours oxygen-glucose deprivation (OGD). A polyphenol trimer from cinnamon (cinnamtannin D1), a polyphenol-rich extract from green tea, and resveratrol prevented the OGD-induced rise in mitochondrial free radicals, cell swelling, and the dissipation of the inner mitochondrial membrane potential. Monocyte chemoattractant protein (also called CCL2), a chemokine, but not tumor necrosis factor-α or interleukin-6, augmented the cell swelling. This effect of monochemoattractant protein 1-1 was attenuated by the polyphenols. Cyclosporin A, a blocker of the mitochondrial permeability transition pore, did not attenuate cell swelling but BAPTA-AM, an intracellular calcium chelator did, indicating a role of [Ca(2+)]i but not the mPT in cell swelling. These results indicate that the polyphenols reduce mitochondrial reactive oxygen species and subsequent cell swelling in endothelial cells following ischemic injury and thus may reduce brain edema and associated neural damage in ischemia. One possible mechanism by which the polyphenols may attenuate endothelial cell swelling is through the reduction in [Ca(2+)]i.

Differential resource allocation in deer mice exposed to sin nombre virus.

PubMed

Lehmer, Erin M; Clay, Christine A; Wilson, Eric; St Jeor, Stephen; Dearing, M Denise

2007-01-01

The resource allocation hypothesis predicts that reproductive activity suppresses immunocompetence; however, this has never been tested in an endemic disease system with free-ranging mammals. We tested the resource allocation hypothesis in wild deer mice (Peromyscus maniculatus) with natural exposure to Sin Nombre Virus (SNV). Immunocompetence was estimated from the extent of swelling elicited after deer mice were injected with phytohemagglutinin (PHA); swelling is positively correlated with immunocompetence. After livetrapping deer mice, we determined their reproductive state and SNV infection status. Males were more likely to be seropositive for SNV than females (37% vs. 25%) and exhibited 10% less swelling after PHA injection. The swelling response of females differed with both infection status and reproductive condition. There was also a significant infection status by reproductive condition interaction: non-reproductive, seropositive females experienced the least amount of swelling, whereas females in all other categories experienced significantly greater swelling. The swelling response of males differed with both SNV infection status and reproductive condition, but there was no significant infection status by reproductive condition interaction. Seronegative males elicited greater swelling than seropositive males regardless of reproductive status. In contrast to the resource allocation hypothesis, these results do not indicate that reproductive activity suppresses immunocompetence of deer mice but rather suggest that chronic SNV infection reduces immunocompetence. Sex-based differences in swelling indicate that SNV modulates the immune system of female deer mice differently than it does that of males, particularly during reproduction. We propose that differences in resource allocation between males and females could result from inherent sex-based differences in parental investment.

Grid pattern of nanothick microgel network.

PubMed

Chen, Guoping; Kawazoe, Naoki; Fan, Yujiang; Ito, Yoshihiro; Tateishi, Tetsuya

2007-05-22

A novel grid pattern of two kinds of nanothick microgels was developed by alternate patterning using photolithography. At first, 100-microm-wide nanothick PAAm microgel stripes were grafted on a polystyrene surface by UV irradiation of the photoreactive azidobenzoyl-derivatized polyallylamine-coated surface through a photomask with 100-microm-wide stripes. Then, a second set of 100-microm-wide nanothick PAAc microgel stripes were grafted across the PAAm-grated polystyrene surface by UV irradiation of the photoreactive azidophenyl-derivatized poly(acrylic acid)-coated surface through a photomask placed perpendicularly to the first set of PAAm microgel stripes. The PAAc microgel stripe pattern was formed over the PAAm microgel stripe pattern. The cross angle of the two microgel stripes could be controlled by adjusting the position of the photomask when the second microgel pattern was prepared. Swelling and shrinking of the microgels were investigated by scanning probe microscopy (SPM) in an aqueous solution. SPM observation indicated that the thickness of the gel network was 100 to 500 nm. The regions containing PAAm, PAAc, and the PAAc-PAAm overlapping microgels showed different swelling and shrinking properties when the pH was changed. The PAAm microgel swelled at low pH and shrank at high pH whereas the PAAc microgel swelled at high pH and shrank at low pH. However, the PAAc-PAAm overlapping microgel did not change as significantly as did the two microgels, indicating that the swelling and shrinking of the two gels was partially offset. The pH-induced structural change was repeatedly reversible. The novel grid pattern of nanothick microgels will find applications in various fields such as smart actuators, artificial muscles, sensors, and drug delivery systems as well as in tissue engineering and so forth.

Formulation and evaluation of different floating tablets containing metronidazole to target stomach.

PubMed

Loh, Zhiao C; Elkordy, Amal A

2015-01-01

The purpose of this study is to formulate and develop tablets dosage form containing Metronidazole which has swelling and floating properties as a gastroretentive controlled-release drug delivery system to improve drug bioavailability. Fifteen different formulations of effervescence-forming floating systems were designed using HPMC K15M, xanthan gum, co-povidone, Eudragit® RL PO, pluronic® F-127 and/or polypropylene foam powder as swelling agents and sodium bicarbonate with/ without citric acid as gas-forming agents at different compositions. Six out of these 15 formulations which have satisfactory tablet floating behaviour were further studied with the incorporation of Metronidazole. The tablets were evaluated based on tablet physicochemical properties, floating behaviour, swelling ability and drug dissolution studies which were carried out using 0.1M HCl at 37°C for 8 hours. Furthermore, evaluation of the powder mixtures using Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC) and scanning electron microscope (SEM) were investigated. Most of the tablets show good physicochemical properties except for F11 which contains pluronic® F-127 as its release-retarding matrix-forming polymer. Other formulations show high swelling capacity, ability to float for at least 8 hours in vitro and have sustained drug release characteristics. Data obtained indicated that F3 which contains HPMC (12.5%w/w), xanthan gum (25%w/w), co-povidone (12.5%w/w) and sodium bicarbonate (31.7%w/w) is a suitable formulation with short floating lag time, good floating behaviour and sustained drug release for at least 8 hours in vitro with a zero order kinetic. Combinations of HPMC K15M and xanthan gum as swelling agents show synergistic effect in retarding drug release and are suitable in providing the most sustained drug release system.

Advanced liquefaction using coal swelling and catalyst dispersion techniques. Quarterly progress report, July--September 1993

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

Curtis, C.W.; Gutterman, C.; Chander, S.

The overall objective of this project is to develop a new approach for the direct liquefaction of coal to produce an all-distillate product slate at a sizable cost reduction over current technology. The approach integrates coal selection, pretreatment, coal swelling with catalyst impregnation, liquefaction, product recovery with characterization, alternate bottoms processing, and carrying out a technical assessment including an economic evaluation. The primary coal of this program, Black Thunder subbituminous coal, can be effectively beneficiated to about 3.5 wt % ash using aqueous sulfurous acid pretreatment. This treated coal can be further beneficiated to about 2 wt % ash usingmore » commercially available procedures. All three coals used in this study (Black Thunder, Burning Star bituminous, and Martin Lake lignite) are effectively swelled by a number of solvents. The most effective solvents are those having hetero-functionality. laboratory- and bench-scale liquefaction experimentation is underway using swelled and catalyst impregnated coal samples. Higher coal conversions were observed for the SO{sub 2}-treated subbituminous coal than the raw coal, regardless of catalyst type. Conversions of swelled coal were highest when Molyvan L, molybdenum naphthenate, and nickel octoate, respectively, were added to the liquefaction solvent. The study of bottoms processing consists of combining the ASCOT process which consists of coupling solvent deasphalting with delayed coking to maximize the production of coal-derived liquids while rejecting solids within the coke drum. The asphalt production phase has been completed; representative product has been evaluated. The solvent system for the deasphalting process has been established. Two ASCOT tests produced overall liquid yields (63.3 wt % and 61.5 wt %) that exceeded the combined liquid yields from the vacuum tower and ROSE process.« less

A dual-phase microstructural approach to damage and fracture of Ti 3SiC 2/SiC joints

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

Nguyen, Ba Nghiep; Henager, Charles H.; Kurtz, Richard J.

We investigate the microcracking mechanisms responsible for Ti 3SiC 2/SiC joint damage observed at the macroscopic scale after neutron irradiation experiments in detail. A dual-phase microstructural approach to damage and fracture of Ti 3SiC 2/SiC joints is developed that uses a finely discretized two-phase domain based on a digital image of an actual microstructure involving embedded Ti 3SiC 2 and SiC phases. The behaviors of SiC and Ti 3SiC 2 in the domain are described by the continuum damage mechanics (CDM) model reported in Nguyen et al., J. Nucl. Mater., 2017, 495:504–515. This CDM model describes microcracking damage in brittlemore » ceramics caused by thermomechanical loading and irradiation-induced swelling. The dual-phase microstructural model is applied to predict the microcracking mechanisms occurring in a typical Ti 3SiC 2/SiC joint subjected to heating to 800 °C followed by irradiation-induced swelling at this temperature and cooling to room temperature after the applied swelling has reached the maximum swelling levels observed in the experiments for SiC and Ti 3SiC 2. The model predicts minor damage of the joint after heating but significant microcracking in the SiC phase and along the boundaries between SiC and Ti 3SiC 2 as well as along the bonding joint during irradiation-induced swelling and cooling to room temperature. Our predictions qualitatively agree with the limited experimental observations of joint damage at this irradiation temperature.« less

A dual-phase microstructural approach to damage and fracture of Ti 3SiC 2/SiC joints

DOE PAGES

Nguyen, Ba Nghiep; Henager, Charles H.; Kurtz, Richard J.

2017-12-05

We investigate the microcracking mechanisms responsible for Ti 3SiC 2/SiC joint damage observed at the macroscopic scale after neutron irradiation experiments in detail. A dual-phase microstructural approach to damage and fracture of Ti 3SiC 2/SiC joints is developed that uses a finely discretized two-phase domain based on a digital image of an actual microstructure involving embedded Ti 3SiC 2 and SiC phases. The behaviors of SiC and Ti 3SiC 2 in the domain are described by the continuum damage mechanics (CDM) model reported in Nguyen et al., J. Nucl. Mater., 2017, 495:504–515. This CDM model describes microcracking damage in brittlemore » ceramics caused by thermomechanical loading and irradiation-induced swelling. The dual-phase microstructural model is applied to predict the microcracking mechanisms occurring in a typical Ti 3SiC 2/SiC joint subjected to heating to 800 °C followed by irradiation-induced swelling at this temperature and cooling to room temperature after the applied swelling has reached the maximum swelling levels observed in the experiments for SiC and Ti 3SiC 2. The model predicts minor damage of the joint after heating but significant microcracking in the SiC phase and along the boundaries between SiC and Ti 3SiC 2 as well as along the bonding joint during irradiation-induced swelling and cooling to room temperature. Our predictions qualitatively agree with the limited experimental observations of joint damage at this irradiation temperature.« less

Growth of the interaction layer around fuel particles in dispersion fuel

NASA Astrophysics Data System (ADS)

Olander, D.

2009-01-01

Corrosion of uranium particles in dispersion fuel by the aluminum matrix produces interaction layers (an intermetallic-compound corrosion product) around the shrinking fuel spheres. The rate of this process was modeled as series resistances due to Al diffusion through the interaction layer and reaction of aluminum with uranium in the fuel particle to produce UAl x. The overall kinetics are governed by the relative rates of these two steps, the slowest of which is reaction at the interface between Al in the interaction layer and U in the fuel particle. The substantial volume change as uranium is transferred from the fuel to the interaction layer was accounted for. The model was compared to literature data on in-reactor growth of the interaction layer and the Al/U gradient in this layer, the latter measured in ex-reactor experiments. The rate constant of the Al-U interface reaction and the diffusivity of Al in the interaction layer were obtained from this fitting procedure. The second feature of the corrosion process is the transfer of fission products from the fuel particle to the interaction layer due to the reaction. It is commonly assumed that the observed swelling of irradiated fuel elements of this type is due to release of fission gas in the interaction layer to form large bubbles. This hypothesis was tested by using the model to compute the quantity of fission gas available from this source and comparing the pressure of the resulting gas with the observed swelling of fuel plates. It was determined that the gas pressure so generated is too small to account for the observed delamination of the fuel.

Fundamental properties of monolithic bentonite buffer material formed by cold isostatic pressing for high-level radioactive waste repository

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

Kawakami, S.; Yamanaka, Y.; Kato, K.

1999-07-01

The methods of fabrication, handling, and emplacement of engineered barriers used in a deep geological repository for high level radioactive waste should be planned as simply as possible from the engineering and economic viewpoints. Therefore, a new concept of a monolithic buffer material around a waste package have been proposed instead of the conventional concept with the use of small blocks, which would decrease the cost for buffer material. The monolithic buffer material is composed of two parts of highly compacted bentonite, a cup type body and a cover. As the forming method of the monolithic buffer material, compaction bymore » the cold isostatic pressing process (CIP) has been employed. In this study, monolithic bentonite bodies with the diameter of about 333 mm and the height of about 455 mm (corresponding to the approx. 1/5 scale for the Japanese reference concept) were made by the CIP of bentonite powder. The dry densities: {rho}d of the bodies as a whole were measured and the small samples were cut from several locations to investigate the density distribution. The swelling pressure and hydraulic conductivity as function of the monolithic body density for CIP-formed specimens were also measured. High density ({rho}d: 1.4--2.0 Mg/m{sup 3}) and homogeneous monolithic bodies were formed by the CIP. The measured results of the swelling pressure (3--15 MPa) and hydraulic conductivity (0.5--1.4 x 10{sup {minus}13} m/s) of the specimens were almost the same as those for the uniaxial compacted bentonite in the literature. It is shown that the vacuum hoist system is an applicable handling method for emplacement of the monolithic bentonite.« less

Swelling and gas release in oxide fuels during fast temperature transients

NASA Astrophysics Data System (ADS)

Dollins, C. C.; Jursich, M.

1982-05-01

A previously reported intergranular swelling and gas release model for oxide fuels has been modified to predict fission gas behavior during fast temperature transients. Under steady state or slowly varying conditions it has been assumed in the previous model that the pressure caused by the fission gas within the gas bubbles is in equilibrium with the surface tension of the bubbles. During a fast transient, however, net vacancy migration to the bubbles may be insufficient to maintain this equilibrium. In order to ascertain the net vacancy flow, it is necessary to model the point defect behavior in the fuel. Knowing the net flow of vacancies to the bubble and the bubble size, the bubble diffusivity can be determined and the long range migration of the gas out of the fuel can be calculated. The model has also been modified to allow release of all the gas on the grain boundaries during a fast temperature transient. The gas release predicted by the revised model shows good agreement to fast transient gas release data from an EBR-II TREAT H-3 (Transient Reactor Test Facility) test. Agreement has also been obtained between predictions using the model and gas release data obtained by Argonne National Laboratory from out-of-reactor transient heating experiments on irradiated UO 2. It was found necessary to increase the gas bubble diffusivity used in the model by a factor of thirty during the transient to provide agreement between calculations and measurements. Other workers have also found that such an increase is necessary for agreement and attribute the increased diffusivity to yielding at the bubble surface due to the increased pressure.

The effect of complementary therapies on post-operative pain control in ambulatory knee surgery: a systematic review.

PubMed

Barlow, Timothy; Downham, Christopher; Barlow, David

2013-10-01

Ambulatory knee surgery is a common procedure with over 100,000 knee arthroscopies performed in the U.K. in 2010-2011. Pain after surgery can decrease patient satisfaction, delay discharge, and decrease cost effectiveness. Multi-modal therapies, including complementary therapies, to improve pain control after surgery have been recommended. However, a comprehensive review of the literature regarding the use of complementary therapies to enhance pain control after ambulatory knee surgery is lacking, and this article aims to address this deficit. CINHAL, EMBASE, MEDLINE, AMED and CENTRAL databases were searched. Only Randomised Controlled Trials were included. All eligible papers were quality assessed using the Jadad system, and data was extracted using piloted forms. Two independent reviewers performed each stage of the review. Full details of the study methodology can be found on Prospero, a systematic review register. Five studies satisfied our eligibility criteria: three reporting on acupuncture, one on homeopathy, and one on acupoints. Acupoint pressure was the only study that demonstrated reduced pain compared with placebo. This study was the least methodologically robust. Arnica, although demonstrating a significant reduction in swelling, did not affect post-operative pain. Acupuncture did not affect post-operative pain; however, a reduction in ibuprofen use was demonstrated in two studies. Before recommending complementary therapy for routine use in ambulatory knee surgery, further work is required. Two areas of future research likely to bear fruit are demonstrating robust evidence for the effect of acupoint pressure on post-operative pain, and quantifying the positive effect of homeopathic arnica on post-operative swelling. Copyright © 2013 Elsevier Ltd. All rights reserved.

Swelling pavements : KY 499 Estill County.

DOT National Transportation Integrated Search

2006-03-01

A field laboratory investigation was performed to determine why excessive swelling was occurring on a pavement section of KY Route 499 that was about four years old. Swelling occurred on a section of roadway that had been constructed with a hydrated ...

Intermittent midline suprasternal neck mass caused by superior herniation of the thymus.

PubMed

Su, Siew Choo; Hess, Thomas; Whybourne, Annie; Chang, Anne B

2015-03-01

Neck masses in infants and children have a wide differential diagnosis. However, neck masses apparent only during raised intrathoracic pressure are rare with a limited number of causes, including superior herniation of the normal thymus, apical lung herniation, jugular phlebectasia and laryngocoele. These conditions can easily be differentiated from one another by imaging. We present an infant with intermittent suprasternal neck mass visible only during increased intrathoracic pressure, produced either by crying or straining. Diagnosis of superior herniation of the thymus into the neck was confirmed by ultrasonography with the characteristic sonographic appearances of the normal thymus as well as its shape, size and location. Ultrasonography should be the first imaging modality of choice. Management of superior herniation of the thymus into the neck should be conservative as the thymus naturally involutes with increasing age. Awareness of the differential diagnosis of neck swelling present only on Vasalva manoeuvre or increased intrathoracic pressure is important to prevent unnecessary tests, avoid radiation, biopsy and surgery. © 2014 The Authors. Journal of Paediatrics and Child Health © 2014 Paediatrics and Child Health Division (Royal Australasian College of Physicians).

Theoretical analysis of swelling characteristics of cylindrical uranium dioxide fuel pins with a niobium - 1-percent-zirconium clad

NASA Technical Reports Server (NTRS)

Saltsman, J. F.

1973-01-01

The relations between clad creep strain and fuel volume swelling are shown for cylindrical UO2 fuel pins with a Nb-1Zr clad. These relations were obtained by using the computer code CYGRO-2. These clad-strain - fuel-volume-swelling relations may be used with any fuel-volume-swelling model, provided the fuel volume swelling is isotropic and independent of the clad restraints. The effects of clad temperature (over a range from 118 to 1642 K (2010 to 2960 R)), pin diameter, clad thickness and central hole size in the fuel have been investigated. In all calculations the irradiation time was 500 hours. The burnup rate was varied.

Micro-structure and Swelling Behaviour of Compacted Clayey Soils: A Quantitative Approach

NASA Astrophysics Data System (ADS)

Ferber, Valéry; Auriol, Jean-Claude; David, Jean-Pierre

In this paper, the clay aggregate volume and inter-aggregate volume in compacted clayey soils are quantified, on the basis of simple hypothesis, using only their water content and dry density. Swelling tests on a highly plastic clay are then interpreted by describing the influence of the inter-aggregate volume before swelling on the total volume of samples after swelling. This approach leads to a linear relation between these latter parameters. Based on these results, a description of the evolution of the microstructure due to imbibition can be proposed. Moreover, this approach enables a general quantification of the influence of initial water content and dry density on the swelling behaviour of compacted clayey soils.

A hemangioma on the floor of the mouth presenting as a ranula.

PubMed

Skoulakis, Charalampos E; Khaldi, Lubna; Serletis, Demetre; Semertzidis, Themistoklis

2008-11-01

A painless, bluish, submucosal swelling on one side of the floor of the mouth usually indicates the presence of a ranula. Rarely, such a swelling may be caused by an inflammatory disease process in a salivary gland, a neoplasm in the sublingual salivary gland, a lymphatic nodular swelling, or embryologic cysts. We report a patient with swelling in the floor of her mouth that was clinically diagnosed as a ranula. Suspicion arose during surgery that it was a vascular tumor and, on histologic testing, the swelling was confirmed to be a hemangioma. To our knowledge, this is the first report in the literature of a hemangioma presenting as a ranula.

Swelling kinetics of spray-dried chitosan acetate assessed by magnetic resonance imaging and their relation to drug release kinetics of chitosan matrix tablets.

PubMed

Huanbutta, Kampanart; Sriamornsak, Pornsak; Limmatvapirat, Sontaya; Luangtana-anan, Manee; Yoshihashi, Yasuo; Yonemochi, Etsuo; Terada, Katsuhide; Nunthanid, Jurairat

2011-02-01

Magnetic resonance imaging (MRI) was used to assess in situ swelling behaviors of spray-dried chitosan acetate (CSA) in 0.1N HCl, pH 6.8 and pH 5.0 Tris-HCl buffers. The in vitro drug releases from CSA matrix tablets containing the model drugs, diclofenac sodium and theophylline were investigated in all media using USP-4 apparatus. The effect of chitosan molecular weight, especially in pH 6.8 Tris-HCl, was also studied. In 0.1N HCl, the drug release from the matrix tablets was the lowest in relation to the highest swelling of CSA. The swelling kinetics in Tris-HCl buffers are Fickian diffusion according to their best fit to Higuchi's model as well as the drug release kinetics in all the media. The high swelling rate (k(s)(')) was found to delay the drug release rate (k'). The linear relationship between the swelling and fractions of drug release in Tris-HCl buffers was observed, indicating an important role of the swelling on controlling the drug release mechanism. Additionally, CSA of 200 and 800 kDa chitosan did not swell in pH 6.8 Tris-HCl but disintegrated into fractions, and the drug release from the matrix tablets was the highest. Copyright © 2010 Elsevier B.V. All rights reserved.

Neck swelling due to skull base (pseudo)meningocele protruding through a congenital skull base bone defect: a case report.

PubMed

Sharma, Rajeev; Singh, Bhoopendra; Kedia, Shweta; Laythalling, Rajinder Kumar

2017-02-01

Meningocele is defined as a protrusion of the meninges through an opening in the skull or spinal column, forming a bulge or sac filled with cerebrospinal fluid. A pseudomeningocele is defined as a cerebrospinal fluid (CSF) collection formed due to escape of CSF through a dural defect with trapping of CSF into the surrounding soft tissues. We herby report rare occurrence of a large (pseudo)meningocele in a young patient with congenital skull base defect presenting as upper lateral neck swelling. We present the case of a 17-year-old boy who had painless progressive swelling right side of the upper neck without any history of meningitis or CSF leak. He had a history of undergoing cranioplasty using steel plates for nontraumatic boggy swelling right parieto-occipital region at the age of 5 years at another hospital. Clinical examination showed painless swelling right side of the upper neck, with positive cough impulse and transillumination. CT head with cisternography showed a large right skull base defect through which a large pseudomeningocele was herniating, thus producing upper neck swelling and compressing oral cavity. The neck swelling and intraoral bulge reduced in size after the coperitoneal shunt. Differential diagnosis of (pseudo)meningocele should be considered while evaluating a painless progressive upper neck swelling having cough impulse and transillumination in a young patient.

Tailor's Bunion (Bunionette)

MedlinePlus

... bony framework, resulting in the development of an enlargement. The fifth metatarsal bone starts to protrude outward, ... swelling and pain at the site of the enlargement. These symptoms occur when wearing shoes that rub ...

Dynamic Regulation of Cell Volume and Extracellular ATP of Human Erythrocytes

PubMed Central

Leal Denis, M. Florencia; Alvarez, H. Ariel; Lauri, Natalia; Alvarez, Cora L.; Chara, Osvaldo; Schwarzbaum, Pablo J.

2016-01-01

Introduction The peptide mastoparan 7 (MST7) triggered in human erythrocytes (rbcs) the release of ATP and swelling. Since swelling is a well-known inducer of ATP release, and extracellular (ATPe), interacting with P (purinergic) receptors, can affect cell volume (Vr), we explored the dynamic regulation between Vr and ATPe. Methods and Treatments We made a quantitative assessment of MST7-dependent kinetics of Vr and of [ATPe], both in the absence and presence of blockers of ATP efflux, swelling and P receptors. Results In rbcs 10 μM MST7 promoted acute, strongly correlated changes in [ATPe] and Vr. Whereas MST7 induced increases of 10% in Vr and 190 nM in [ATPe], blocking swelling in a hyperosmotic medium + MST7 reduced [ATPe] by 40%. Pre-incubation of rbcs with 10 μM of either carbenoxolone or probenecid, two inhibitors of the ATP conduit pannexin 1, reduced [ATPe] by 40–50% and swelling by 40–60%, while in the presence of 80 U/mL apyrase, an ATPe scavenger, cell swelling was prevented. While exposure to 10 μM NF110, a blocker of ATP-P2X receptors mediating sodium influx, reduced [ATPe] by 48%, and swelling by 80%, incubation of cells in sodium free medium reduced swelling by 92%. Analysis and Discussion Results were analyzed by means of a mathematical model where ATPe kinetics and Vr kinetics were mutually regulated. Model dependent fit to experimental data showed that, upon MST7 exposure, ATP efflux required a fast 1960-fold increase of ATP permeability, mediated by two kinetically different conduits, both of which were activated by swelling and inactivated by time. Both experimental and theoretical results suggest that, following MST7 exposure, ATP is released via two conduits, one of which is mediated by pannexin 1. The accumulated ATPe activates P2X receptors, followed by sodium influx, resulting in cell swelling, which in turn further activates ATP release. Thus swelling and P2X receptors constitute essential components of a positive feedback loop underlying ATP-induced ATP release of rbcs. PMID:27355484

A new approach to enhance the selectivity of liberation and the efficiency of coal grinding

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

Wang, X.H.; Guo, Q.; Parekh, B.K.

1993-12-31

An innovative process has been developed at the University of Kentucky to enhance the liberation of mineral matter from coal and the efficiency of grinding energy utilization. Through treating coal with a swelling agent prior to grinding, the grindability of coals can be considerably improved. The Hardgrove Grindability tests show that the HGI of a KY. No. 9 coal increases from 41 for the untreated coal to 60-90 after swelling pretreatment for a short time. Batch stirred ball mill grinding results demonstrate that this new technique has a great potential in reducing the energy consumption of fine coal grinding. Dependingmore » on the pretreatment conditions, the specific energy consumption of producing less than 10 {mu}m product is reduced to 41-60% of that of the untreated coal feed. The production rate of -10 {mu}m particles increases considerably for the pretreated coal. The Energy-Dispersive-X-ray Analytical Scanning Electron Microscope (EDXA-SEM) studies clearly demonstrate that intensive cracking and fracturing were developed during the swelling pretreatment. Cracks and fractures were induced in the coal matrix, preferentially along the boundaries between the pyrite particles and coal matrix. These may be responsible for enhancement in both the efficiency of grinding energy consumption and the selectivity of liberation.« less

A three-dimensional transient mixed hybrid finite element model for superabsorbent polymers with strain-dependent permeability.

PubMed

Yu, Cong; Malakpoor, Kamyar; Huyghe, Jacques M

2018-05-16

A hydrogel is a cross-linked polymer network with water as solvent. Industrially widely used superabsorbent polymers (SAP) are partially neutralized sodium polyacrylate hydrogels. The extremely large degree of swelling is one of the most distinctive characteristics of such hydrogels, as the volume increase can be about 30 times its original volume when exposed to physiological solution. The large deformation resulting from the swelling demands careful numerical treatment. In this work, we present a biphasic continuum-level swelling model using the mixed hybrid finite element method (MHFEM) in three dimensions. The hydraulic permeability is highly dependent on the swelling ratio, resulting in values that are orders of magnitude apart from each other. The property of the local mass conservation of MHFEM contributes to a more accurate calculation of the deformation as the permeability across the swelling gel in a transient state is highly non-uniform. We show that the proposed model is able to simulate the free swelling of a random-shaped gel and the squeezing of fluid out of a swollen gel. Finally, we make use of the proposed numerical model to study the onset of surface instability in transient swelling.

Swelling and Softening of the Cowpea Chlorotic Mottle Virus in Response to pH Shifts

PubMed Central

Wilts, Bodo D.; Schaap, Iwan A.T.; Schmidt, Christoph F.

2015-01-01

Cowpea chlorotic mottle virus (CCMV) forms highly elastic icosahedral protein capsids that undergo a characteristic swelling transition when the pH is raised from 5 to 7. Here, we performed nano-indentation experiments using an atomic force microscope to track capsid swelling and measure the shells’ Young’s modulus at the same time. When we chelated Ca2+ ions and raised the pH, we observed a gradual swelling of the RNA-filled capsids accompanied by a softening of the shell. Control experiments with empty wild-type virus and a salt-stable mutant revealed that the softening was not strictly coupled to the swelling of the protein shells. Our data suggest that a pH increase and Ca2+ chelation lead primarily to a loosening of contacts within the protein shell, resulting in a softening of the capsid. This appears to render the shell metastable and make swelling possible when repulsive forces among the capsid proteins become large enough, which is known to be followed by capsid disassembly at even higher pH. Thus, softening and swelling are likely to play a role during inoculation. PMID:25992732

Irradiation creep and swelling of AISI 316 to exposures of 130 dpa at 385?400$deg;C

NASA Astrophysics Data System (ADS)

Garner, F. A.; Porter, D. L.

1988-07-01

The creep and swelling of AISI 316 stainless steel have been studied at 385 to 400°C in EBR-II to doses of 130 dpa. Most creep capsules were operated at constant stress and temperature but mid-life changes in these variables were also made. This paper concentrates on the behavior of the 20% cold-worked condition but five other conditions were also studied. Swelling at ⩽ 400° C was found to lose the sensitivity to stress exhibited at higher temperatures while the creep rate was found to retain linear dependencies on both stress and swelling rate. The creep coefficients extracted at 400°C agree with those found in other experiments conducted at higher temperatures. In the temperature range of ⩽ 400° C, swelling is in the recombinationdominated regime and the swelling rate falls strongly away from the ~1%/dpa rate observed at higher temperatures. These lower rates of creep and swelling, coupled with the attainment of high damage levels without failure, encourage the use of AISI 316 in the construction of water-cooled fusion first walls operating at temperatures below 400°C.

Acute Hyperglycemia Does Not Affect Brain Swelling or Infarction Volume After Middle Cerebral Artery Occlusion in Rats.

PubMed

McBride, Devin W; Matei, Nathanael; Câmara, Justin R; Louis, Jean-Sébastien; Oudin, Guillaume; Walker, Corentin; Adam, Loic; Liang, Xiping; Hu, Qin; Tang, Jiping; Zhang, John H

2016-01-01

Stroke disproportionally affects diabetic and hyperglycemic patients with increased incidence and is associated with higher morbidity and mortality due to brain swelling. In this study, the intraluminal suture middle cerebral artery occlusion (MCAO) model was used to examine the effects of blood glucose on brain swelling and infarct volume in acutely hyperglycemic rats and normo-glycemic controls. Fifty-four rats were distributed into normo-glycemic sham surgery, hyperglycemic sham surgery, normo-glycemic MCAO, and hyperglycemic MCAO. To induce hyperglycemia, 15 min before MCAO surgery, animals were injected with 50 % dextrose. Animals were subjected to 90 min of MCAO and sacrificed 24 h after reperfusion for hemispheric brain swelling and infarct volume calculations using standard equations. While normo-glycemic and hyperglycemic animals after MCAO presented with significantly higher brain swelling and larger infarcts than their respective controls, no statistical difference was observed for either brain swelling or infarct volume between normo-glycemic shams and hyperglycemic shams or normo-glycemic MCAO animals and hyperglycemic MCAO animals. The findings of this study suggest that blood glucose does not have any significant effect on hemispheric brain swelling or infarct volume after MCAO in rats.

Modeling the effects of pH and ionic strength on swelling of anionic polyelectrolyte gels

NASA Astrophysics Data System (ADS)

Drozdov, A. D.; deClaville Christiansen, J.

2015-07-01

A constitutive model is developed for the elastic response of an anionic polyelectrolyte gel under swelling in water with an arbitrary pH and an arbitrary molar fraction of dissolved monovalent salt. A gel is treated as a three-phase medium consisting of a solid phase (polymer network), solvent (water), and solute (mobile ions). Transport of solvent and solute is thought of as their diffusion through the polymer network accelerated by an electric field formed by mobile and fixed ions and accompanied by chemical reactions (dissociation of functional groups attached to polymer chains and formation of ion pairs between bound charges and mobile counter-ions). Constitutive equations are derived by means of the free energy imbalance inequality for an arbitrary three-dimensional deformation with finite strains. These relations are applied to analyze equilibrium swelling diagrams on poly(acrylic acid) gel, poly(methacrylic acid) gel, and three composite hydrogels under water uptake in a bath (i) with a fixed molar fraction of salt and varied pH, and (ii) with a fixed pH and varied molar fraction of salt. To validate the ability of the model to predict observations quantitatively, material constants are found by matching swelling curves under one type of experimental conditions and results of simulation are compared with experimental data in the other type of tests.

Docosahexaenoic acid supplementation alters key properties of cardiac mitochondria and modestly attenuates development of left ventricular dysfunction in pressure overload-induced heart failure.

PubMed

Dabkowski, Erinne R; O'Connell, Kelly A; Xu, Wenhong; Ribeiro, Rogerio F; Hecker, Peter A; Shekar, Kadambari Chandra; Daneault, Caroline; Des Rosiers, Christine; Stanley, William C

2013-12-01

Supplementation with the n3 polyunsaturated fatty acid docosahexaenoic acid (DHA) is beneficial in heart failure patients, however the mechanisms are unclear. DHA is incorporated into membrane phospholipids, which may prevent mitochondrial dysfunction. Thus we assessed the effects of DHA supplementation on cardiac mitochondria and the development of heart failure caused by aortic pressure overload. Pathological cardiac hypertrophy was generated in rats by thoracic aortic constriction. Animals were fed either a standard diet or were supplemented with DHA (2.3 % of energy intake). After 14 weeks, heart failure was evident by left ventricular hypertrophy and chamber enlargement compared to shams. Left ventricle fractional shortening was unaffected by DHA treatment in sham animals (44.1 ± 1.6 % vs. 43.5 ± 2.2 % for standard diet and DHA, respectively), and decreased with heart failure in both treatment groups, but to a lesser extent in DHA treated animals (34.9 ± 1.7 %) than with the standard diet (29.7 ± 1.5 %, P < 0.03). DHA supplementation increased DHA content in mitochondrial phospholipids and decreased membrane viscosity. Myocardial mitochondrial oxidative capacity was decreased by heart failure and unaffected by DHA. DHA treatment enhanced Ca(2+) uptake by subsarcolemmal mitochondria in both sham and heart failure groups. Further, DHA lessened Ca(2+)-induced mitochondria swelling, an index of permeability transition, in heart failure animals. Heart failure increased hydrogen peroxide-induced mitochondrial permeability transition compared to sham, which was partially attenuated in interfibrillar mitochondria by treatment with DHA. DHA decreased mitochondrial membrane viscosity and accelerated Ca(2+) uptake, and attenuated susceptibility to mitochondrial permeability transition and development of left ventricular dysfunction.

[Rhabdomyolysis after lifting IKEA bags in a man using sertraline].

PubMed

Kummen, Ingvild; Jensen, Thomas Giver

2016-12-12

We present a case of a 28-year-old male, using sertraline, who experienced progressive oedema in both upper extremities after having lifted two IKEA bags weighing 20 kg each from his car up to the third floor. Blood creatine kinase (CK) level was measured 5,260 U/l, and the patient was admitted for oral rehydration with the diagnosis rhabdomyolysis. The MRI showed swelling in the triceps muscles and latissimus dorsi muscles resulting in compression of the brachial vein. We discuss the pathomechanism behind the increased CK level and the swelling, and the possible effect sertraline may have had on the development of rhabdomyolysis.

Equilibrium swelling properties of polyampholytic hydrogels

NASA Astrophysics Data System (ADS)

English, Anthony E.; Mafé, Salvador; Manzanares, José A.; Yu, Xiahong; Grosberg, Alexander Yu.; Tanaka, Toyoichi

1996-06-01

The role of counter ions and ion dissociation in establishing the equilibrium swelling of balanced and unbalanced polyampholytic hydrogels has been investigated experimentally and theoretically. The swelling dependence on both the net charge offset and the external bath salt concentration has been examined using an acrylamide based polyampholytic hydrogels. By careful consideration of the swelling kinetics, we illustrate the effects of ion dissociation equilibria and counter ion shielding in polyampholytic hydrogels near their balance point where both polyelectrolyte and polyampholyte effects are present. The theory considers a Flory type swelling model where the Coulombic interactions between fixed ions in the hydrogel resemble those of an ionic solid with a Debye screening factor. Theoretical predictions from this model are in qualitative agreement with our experimental results.

A new serotyping method for Klebsiella species: evaluation of the technique.

PubMed Central

Riser, E; Noone, P; Bonnet, M L

1976-01-01

A new indirect fluorescent typing method for Klebsiella species is compared with an established method, capsular swelling. The fluorescent antibody (FA) technique was tested with standards and unknowns, and the results were checked by capsular swelling. Several unknowns were sent away for confirmation of typing, by capsular swelling. The FA method was also tried by a technician in the routine department for blind identification of standards. Fluorescence typing gives close correlation with the established capsular swelling technique but has greater sensitivity; allows more econimical use of expensive antisera; possesses greater objectivity as it requires less operator skill in the reading of results; resolves most of the cross reactions observed with capsular swelling; and has a higher per cent success rate in identification. PMID:777043

Post-irradiation examination of prototype Al-64 wt% U{sub 3}Si{sub 2} fuel rods from NRU

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

Sears, D.F.; Primeau, M.F.; Buchanan, C.

1997-08-01

Three prototype fuel rods containing Al-64 wt% U{sub 3}Si{sub 2} (3.15 gU/cm{sup 3}) have been irradiated to their design burnup in the NRU reactor without incident. The fuel was fabricated using production-scale equipment and processes previously developed for Al-U{sub 3}Si fuel fabrication at Chalk River Laboratories, and special equipment developed for U{sub 3}Si{sub 2} powder production and handling. The rods were irradiated in NRU up to 87 at% U-235 burnup under typical driver fuel conditions; i.e., nominal coolant inlet temperature 37{degrees}C, inlet pressure 654 kPa, mass flow 12.4 L/s, and element linear power ratings up to 73 kW/m. Post-irradiation examinationsmore » showed that the fuel elements survived the irradiation without defects. Fuel core diametral increases and volumetric swelling were significantly lower than that of Al-61 wt% U{sub 3}Si fuel irradiated under similar conditions. This irradiation demonstrated that the fabrication techniques are adequate for full-scale fuel manufacture, and qualified the fuel for use in AECL`s research reactors.« less

Nasal Bubble CPAP: One Year Experience in a Neonatal Unit of a Tertiary Health Facility in Northwestern Nigeria.

PubMed

Abdulkadir, I; Hassan, L; Abdullahi, F; Purdue, S; Ogala, W N

2015-03-01

Nasal bubble continuous positive airway pressure (NBCPAP) respiratory support, though decades old, is beginning to gain popularity in developing countries including Nigeria. We reviewed neonates who benefitted from NBCPAP, to describe the demographics and outcome of NBCPAP respiratory support in newborns admitted to the neonatal unit of Ahmadu Bello University Teaching Hospital (ABUTH), Zaria, over a one year period. The study is a descriptive observational review of all neonates who required NBCPAP respiratory support in the neonatal unit of ABUTH Zaria. Data was extracted from a specifically designed proforma used to obtain information on each neonate throughout the period of admission. Twenty babies received NBCPAP respiratory support during the period of study. Seventeen (85%) of the neonates were successfully weaned off CPAP while three (15%) failed CPAP. Three neonates developed complications with two having CPAP belly syndrome and the third had facial swelling which resolved spontaneously after 6 hours. Overall, seven (41%) of the neonates who were successfully weaned off CPAP were discharged home. MajorityofnewbornswhorequirerespiratorysupportwillbenefitfromNBCPAP therefore, this method of respiratory support should be popularized and neonatal units in the country should be supported to efficiently offer the service.

[Eosin Y-water test for sperm function examination].

PubMed

Zha, Shu-wei; Lü, Nian-qing; Xu, Hao-qin

2015-06-01

Based on the principles of the in vitro staining technique, hypotonic swelling test, and water test, the Eosin Y-water test method was developed to simultaneously detect the integrity of the sperm head and tail and sperm membrane structure and function. As a widely used method in clinical laboratories in China, the Eosin Y-water test is methodologically characterized by three advantages. Firstly, both the sperm head and tail can be detected at the same time, which allows easy and comprehensive assessment of membrane damage in different parts of sperm. Secondly, distilled water is used instead of the usual formula solution to simplify and standardize the test by eliminating any potential effects on the water molecules through the sperm membrane due to different osmotic pressure or different sugar proportions and electrolyte solutions. Thirdly, the test takes less time and thus can be repeated before and after treatment. This article focuses on the fundamental principles and modification of the Eosin Y-water test and its application in sperm function examination and routine semen analysis for male infertility, assessment of the quality of sperm retrieved by testicular fine needle aspiration, semen cryopreservation program development, and evaluation of sperm membrane integrity after microwave radiation.

Characterization and swelling-deswelling properties of wheat straw cellulose based semi-IPNs hydrogel.

PubMed

Liu, Jia; Li, Qian; Su, Yuan; Yue, Qinyan; Gao, Baoyu

2014-07-17

A novel wheat straw cellulose-g-poly(potassium acrylate)/polyvinyl alcohol (WSC-g-PKA/PVA) semi-interpenetrating polymer networks (semi-IPNs) hydrogel was prepared by polymerizing wheat straw and an aqueous solution of acrylic acid (AA), and further semi-interpenetrating with PVA occurred during the chemosynthesis. The swelling and deswelling properties of WSC-g-PKA/PVA semi-IPNs hydrogel and WSC-g-PKA hydrogel were studied and compared in various pH solutions, salt solutions, temperatures, particle sizes and ionic strength. The results indicated that both hydrogels had the largest swelling capacity at pH=6, and the effect of ions on the swelling of hydrogels was in the order: Na(+)>K(+)>Mg(2+)>Ca(2+). The Schott's pseudo second order model can be effectively used to evaluate swelling kinetics of hydrogels. Moreover, the semi-IPNs hydrogel had improved swelling-deswelling properties compared with that of WSC-g-PKA hydrogel. Copyright © 2014 Elsevier Ltd. All rights reserved.

Impact of salt form and molecular weight of chitosan on swelling and drug release from chitosan matrix tablets.

PubMed

Huanbutta, Kampanart; Cheewatanakornkool, Kamonrak; Terada, Katsuhide; Nunthanid, Jurairat; Sriamornsak, Pornsak

2013-08-14

Magnetic resonance imaging (MRI) and gravimetric techniques were used to assess swelling and erosion behaviors of hydrophilic matrix tablets made of chitosan. The impact of salt form, molecular weight (MW) and dissolution medium on swelling behavior and drug (theophylline) release was studied. The matrix tablets made of chitosan glycolate (CGY) showed the greatest swelling in both acid and neutral media, compared to chitosan aspartate, chitosan glutamate and chitosan lactate. MRI illustrated that swelling region of CGY in both media was not different in the first 100 min but glassy region (dry core) in 0.1N HCl was less than in pH 6.8 buffer. The tablets prepared from chitosan with high MW swelled greater than those of low MW. Moreover, CGY can delay drug release in the acid condition due to thick swollen gel and low erosion rate. Therefore, CGY may be suitably applied as sustained drug release polymer or enteric coating material. Copyright © 2013 Elsevier Ltd. All rights reserved.

Utility of ultrasonography for diagnosis of superficial swellings in buffalo (Bubalus bubalis)

PubMed Central

ABOUELNASR, Khaled; EL-SHAFAEY, El-Sayed; MOSBAH, Esam; EL-KHODERY, Sabry

2016-01-01

We studied 72 buffalo with superficial swellings in the head (n=4), neck (n=5), chest wall (n=4), abdominal wall (n=28), limbs (n=16), gluteal region (n=8), perineal region (n=6) and udder (n=1). Ultrasonographically, the swellings varied according to type, duration, content and location. The clinical use of ultrasound to assess these superficial swellings allowed diagnosis of abscesses (n=21), hematomas (n=11), hernias (n=17), bursitis (n=13), urethral diverticula (n=6) and tumors (n=4). Ultrasonography could precisely discriminate each lesion type (sensitivity, 71–100%; specificity, 75–100%; odds ratio, 1.0–8.4; Confidence Interval, 74.2–20; and P value 0.001). The specificity for ultrasonographic evaluation of superficial swellings was 100% for hernias, urethral diverticula and tumors, whilst the lowest specificity was recorded for hematomas (75%) and abscesses (92%). In conclusion, ultrasonography provides a precise, non-invasive and fast technique for the evaluation, classification and subsequent treatment of a variety of superficial swellings in buffalo. PMID:27181085

Development, optimization and evaluation of curcumin loaded biodegradable crosslinked gelatin film for the effective treatment of periodontitis.

PubMed

Chauhan, Sheetal; Bansal, Monika; Khan, Gayasuddin; Yadav, Sarita K; Singh, Ashish K; Prakash, Pradyot; Mishra, Brahmeshwar

2018-07-01

Aim of the present study was to prepare curcumin (CUR) loaded biodegradable crosslinked gelatin (GE) film to alleviate the existing shortcomings in the treatment of periodontitis. Gelatin film was optimized to provide anticipated mucoadhesive strength, mechanical properties, folding endurance, and prolonged drug release over treatment duration, for successful application in the periodontitis. The film was developed by using solvent casting technique and "Design of Experiments" approach was employed for evaluating the influence of independent variables on dependent response variables. Solid-state characterization of the film was performed by FTIR, XRD, and SEM. Further, prepared formulations were evaluated for drug content uniformity, surface pH, folding endurance, swelling index, mechanical strength, mucoadhesive strength, in vitro biodegradation, and in vitro drug release behavior. Solid state characterization of the formulation showed that CUR is physico-chemically compatible with other excipients and CUR was entrapped in an amorphous form inside the smooth and uniform film. The optimized film showed degree of crosslinking 51.04 ± 2.4, swelling index 138.10 ± 1.25, and folding endurance 270 ± 3 with surface pH around 7.0. Crosslinker concentrations positively affected swelling index and biodegradation of film due to altered matrix density of the polymer. Results of in vitro drug release demonstrated the capability of the developed film for efficiently delivering CUR in a sustained manner up to 7 days. The developed optimized film could be considered as a promising delivery strategy to administer medicament locally into the periodontal pockets for the safe and efficient management of periodontitis.

Evaluation about wettability, water absorption or swelling of excipients through various methods and the correlation between these parameters and tablet disintegration.

PubMed

Yang, Baixue; Wei, Chen; Yang, Yang; Wang, Qifang; Li, Sanming

2018-04-06

To evaluate parameters about wettability, water absorption or swelling of excipients in forms of powders or dosage through various methods systematically and explore its correlation with tablet disintegration. The water penetration and swelling of powders with different proportions of excipients including microcrystalline cellulose (MCC), mannitol, low-substituted hydroxypropyl cellulose (L-HPC), crospolyvinylpyrrolidone (PVPP), carboxymethyl starch sodium (CMS-Na), croscarmellose sodium (CCMC-Na) and magnesium stearate (MgSt) were determined by Washburn capillary rise. Both contact angle of water on the excipient compacts and surface swelling volume were measured by sessile drop technique. Moreover, the test about water absorption and swelling of compacts was fulfilled by a modified method. Eventually, the disintegration of tablets with or without loratadine was performed according to the method described in USP. These parameters were successfully identified by the methods above, which proved that excipient wettability or swelling properties varied with the structure of excipients. For example, MgSt could improve the water uptake, while impeded tablet swelling. Furthermore, in the present study it is verified that tablet disintegration was closely related to these parameters, especially wetting rate and initial water absorption rate. The higher wetting rate of water on tablet or initial water absorption rate, the faster swelling it be, resulting in the shorter tablet disintegration time. The methods utilized in the present study were feasible and effective. The disintegration of tablets did relate to these parameters, especially wetting rate and initial water absorption rate.

Lesch-Nyhan syndrome

MedlinePlus

... recycle purines. Without it, abnormally high levels of uric acid build up in the body. ... Too much uric acid can cause gout-like swelling in some of the joints. In some cases, kidney and bladder stones develop. ...

Development of the West Virginia University Small Microgravity Research Facility (WVU SMiRF)

NASA Astrophysics Data System (ADS)

Phillips, Kyle G.

West Virginia University (WVU) has created the Small Microgravity Research Facility (SMiRF) drop tower through a WVU Research Corporation Program to Stimulate Competitive Research (PSCoR) grant on its campus to increase direct access to inexpensive and repeatable reduced gravity research. In short, a drop tower is a tall structure from which experimental payloads are dropped, in a controlled environment, and experience reduced gravity or microgravity (i.e. "weightlessness") during free fall. Currently, there are several methods for conducting scientific research in microgravity including drop towers, parabolic flights, sounding rockets, suborbital flights, NanoSats, CubeSats, full-sized satellites, manned orbital flight, and the International Space Station (ISS). However, none of the aforementioned techniques is more inexpensive or has the capability of frequent experimentation repeatability as drop tower research. These advantages are conducive to a wide variety of experiments that can be inexpensively validated, and potentially accredited, through repeated, reliable research that permits frequent experiment modification and re-testing. Development of the WVU SMiRF, or any drop tower, must take a systems engineering approach that may include the detailed design of several main components, namely: the payload release system, the payload deceleration system, the payload lifting and transfer system, the drop tower structure, and the instrumentation and controls system, as well as a standardized drop tower payload frame for use by those researchers who cannot afford to spend money on a data acquisition system or frame. In addition to detailed technical development, a budgetary model by which development took place is also presented throughout, summarized, and detailed in an appendix. After design and construction of the WVU SMiRF was complete, initial calibration provided performance characteristics at various payload weights, and full-scale checkout via experimentation provided repeatability characteristics of the facility. Based on checkout instrumentation, Initial repeatability results indicated a drop time of 1.26 seconds at an average of 0.06g, with a standard deviation of 0.085g over the period of the drop, and a peak impact load of 28.72g, with a standard deviation of 10.73g, for a payload weight of 113.8 lbs. In order to thoroughly check out the facility, a full-scale, fully operational experiment was developed to create an experience that provides a comprehensive perspective of the end-user experience to the developer, so as to incorporate the details that may have been overlooked to the designer and/or developer, in this case, Kyle Phillips. The experiment that was chosen was to determine the effects of die swell, or extrudate swell, in reduced gravity. Die swell is a viscoelastic phenomenon that occurs when a dilatant, or shear-thickening substance is forced through a sufficient constriction, or "die," such that the substance expands, or "swells," downstream of the constriction, even while forming and maintaining a free jet at ambient sea level conditions. A wide range of dilatants exhibit die swell when subjected to the correct conditions, ranging from simple substances such as ketchup, oobleck, and shampoo to complex specially-formulated substances to be used for next generation body armor and high performance braking systems. To date, very few, if any, have researched the stabilizing effect that gravity may have on the phenomenon of die swell. By studying a fluid phenomenon in a reduced gravity environment, both the effect of gravity can be studied and the predominant forces acting on the fluid can be concluded. Furthermore, a hypothesis describing the behavior of a viscoelastic fluid particle employing the viscous Navier-Stokes Equations was derived to attempt to push the fluid mechanics community toward further integrating more fluid behavior into a unified mathematical model of fluid mechanics. While inconclusive in this experiment, several suggestions for future research were made in order to further the science behind die swell, and a comprehensive checkout of the facility and its operations were characterized. As a result of this checkout experience, several details were modified or added to the facility in order for the drop tower to be properly operated and provide the optimal user experience, such that open operation of the WVU SMiRF may begin in the Fall of 2014.

[Effects of medullary ischemia on respiratory and blood pressure induced by ligating basilar artery in cat].

PubMed

Zhuang, Xu; Guo, Jun-Xia; Zhang, Cheng-Wu; Zheng, Yu

2003-11-01

Observations on medullary ischemia region, the morphology of neurons and changes of respiration and blood pressure were made, in order to give evidences on how medullary ischemia affects respiration and circulation and give some advices on how to protect from it. Using cats as the experimental animals, the different parts of the basilar artery trunk were ligated. The changes in the density of blood vessels, the morphology of neurons in the brainstem, the electromyogram (EMG) of the diaphragm and the blood pressure of the femoral artery were investigated. The density of blood vessels notably decreased in the medulla after ligating the basilar artery trunk. The ischemic range induced by ligation of the different parts of the basilar artery trunk overlapped, mainly locating in the medulla rostral to the obex. The soma were swelled and the Nissl bodies decreased in some of neurons in the ischemic region of medulla. The duration of inspiration (T1) and expiration (TE) shortened, respiratory frequency (RF) increased, and mean blood pressure (MBP) decreased in the experimental groups (P < 0.05). There is an obvious overlap of the areas in which blood supplied by different parts of the basilar artery trunk. Medullary ischemia can involve in changes of respiration and blood pressure. The ischemic damage of neurons in the medulla might be the structural basis of the changes in the respiratory and circulatory functions.

The Multi-Porosity Multi-Permeability and Electrokinetic Natures of Shales and Their Effects in Hydraulic Fracturing of Unconventional Shale Reservoirs

NASA Astrophysics Data System (ADS)

Liu, C.; Hoang, S. K.; Tran, M. H.; Abousleiman, Y. N.

2013-12-01

Imaging studies of unconventional shale reservoir rocks have recently revealed the multi-porosity multi-permeability nature of these intricate formations. In particular, the porosity spectrum of shale reservoir rocks often comprises of the nano-porosity in the organic matters, the inter-particle micro-porosity, and the macroscopic porosity of the natural fracture network. Shale is also well-known for its chemically active behaviors, especially shrinking and swelling when exposed to aqueous solutions, as the results of pore fluid exchange with external environment due to the difference in electro-chemical potentials. In this work, the effects of natural fractures and electrokinetic nature of shale on the formation responses during hydraulic fracturing are examined using the dual-poro-chemo-electro-elasticity approach which is a generalization of the classical Biot's poroelastic formulation. The analyses show that the presence of natural fractures can substantially increase the leak-off rate of fracturing fluid into the formation and create a larger region of high pore pressure near the fracture face as shown in Fig.1a. Due to the additional fluid invasion, the naturally fractured shale swells up more and the fracture aperture closes faster compared to an intrinsically low permeability non-fractured shale formation as shown in Fig.1b. Since naturally fractured zones are commonly targeted as pay zones, it is important to account for the faster fracture closing rate in fractured shales in hydraulic fracturing design. Our results also show that the presence of negative fixed charges on the surface of clay minerals creates an osmotic pressure at the interface of the shale and the external fluid as shown in Fig.1c. This additional Donnan-induced pore pressure can result in significant tensile effective stresses and tensile damage in the shale as shown in Fig.1d. The induced tensile damage can exacerbate the problem of proppant embedment resulting in more fracture closure and reduction of fracture length and productivity. The results also suggest that a fracturing fluid with appropriately designed salinity can minimize the chemically induced tensile damage and, thus, maximize the productivity from the created hydraulic fractures.

Using the adaptive SMA composite cylinder concept to reduce radial dilation in composite pressure vessels

NASA Astrophysics Data System (ADS)

Paine, Jeffrey S.; Rogers, Craig A.

1995-05-01

Composite materials are widely used in the design of pressurized gas and fluid vessels for applications ranging from underground gasoline storage tanks to rocket motors for the space shuttle. In the design of a high pressure composite vessel (Pi > 12 Ksi), thick-wall (R/h < 15) vessels are required. For efficient material use in composite material vessels, the radial dilation (expansion or swelling) of the composite vessel can often approach values nearing 2 percent of the diameter. Over long periods of internal pressure loading over elevated temperatures, composite material cylinders may also experience substantial creep. The short term dilation and long term creep are not problematic for applications requiring only the containment of the pressurized fluid. In applications where metallic liners are required, however, substantial dilation and creep causes plastic yielding which leads to reduced fatigue life. To applications such as a hydraulic accumulator, where a piston is employed to fit and seal the fluid in the composite cylinder, the dilation and creep may allow leakage and pressure loss around the piston. A concept called the adaptive composite cylinder is experimentally presented. Shape memory alloy wire in epoxy resin is wrapped around or within polymer matrix composite cylinders to reduce radial dilation of the cylinder. Experimental results are presented that demonstrate the ability of the SMA wire layers to reduce radial dilation. Results from experimental testing of the recovery stress fatigue response of nitinol shape memory alloy wires is also presented.

Blockade of the swelling-induced chloride current attenuates the mouse neonatal hypoxic-ischemic brain injury in vivo.

PubMed

Wong, Raymond; Abussaud, Ahmed; Leung, Joseph Wh; Xu, Bao-Feng; Li, Fei-Ya; Huang, Sammen; Chen, Nai-Hong; Wang, Guan-Lei; Feng, Zhong-Ping; Sun, Hong-Shuo

2018-05-01

Activation of swelling-induced Cl - current (I Cl,swell ) during neonatal hypoxia-ischemia (HI) may induce brain damage. Hypoxic-ischemic brain injury causes chronic neurological morbidity in neonates as well as acute mortality. In this study, we investigated the role of I Cl,swell in hypoxic-ischemic brain injury using a selective blocker, 4-(2-butyl-6,7-dichloro-2-cyclopentylindan-1-on-5-yl) oxybutyric acid (DCPIB). In primary cultured cortical neurons perfusion of a 30% hypotonic solution activated I Cl,swell , which was completely blocked by the application of DCPIB (10 μmol/L). The role of I Cl,swell in neonatal hypoxic-ischemic brain injury in vivo was evaluated in a modified neonatal hypoxic-ischemic brain injury model. Before receiving the ischemic insult, the mouse pups were injected with DCPIB (10 mg/kg, ip). We found that pretreatment with DCPIB significantly reduced the brain damage assessed using TTC staining, Nissl staining and whole brain imaging, and improved the sensorimotor and vestibular recovery outcomes evaluated in neurobehavioural tests (i.e. geotaxis reflex, and cliff avoidance reflex). These results show that DCPIB has neuroprotective effects on neonatal hypoxic-ischemic brain injury, and that the I Cl,swell may serve as a therapeutic target for treatment of hypoxic-ischemic encephalopathy.

Comparison of pain and swelling after removal of oral leukoplakia with CO2 laser and cold knife: A randomized clinical trial

PubMed Central

López-Jornet, Pía

2013-01-01

Objective: The aim of this study was to compare conventional surgery with carbon dioxide (CO2) laser in patients with oral leukoplakia, and to evaluate the postoperative pain and swelling. Study design: A total of 48 patients (27 males and 21 females) with a mean age of 53.7 ± 11.7 years and diagnosed with oral leukoplakia were randomly assigned to receive treatment either with conventional surgery using a cold knife or with a CO2 laser technique. A visual analog scale (VAS) was used to score pain and swelling at different postoperative time points. Results: Pain and swelling reported by the patients was greater with the conventional cold knife than with the CO2 laser, statistically significant differences for pain and swelling were observed between the two techniques during the first three days after surgery. Followed by a gradual decrease over one week. In neither group was granuloma formation observed, and none of the patients showed malignant transformation during the period of follow-up. Conclusions: The CO2 laser causes only minimal pain and swelling, thus suggesting that it may be an alternative method to conventional surgery in treating patients with oral leukoplakia. Key words:Oral leukoplakia, treatment, laser surgery, cold knife, pain, swelling. PMID:23229239

Urinary steroid hormone analysis of ovarian cycles and pregnancy in mandrills (Mandrillus sphinx) indicate that menses, copulatory behavior, sexual swellings and reproductive condition are associated with changing estrone conjugates (E(1)C) and pregnanediol-3-glucuronide (PdG).

PubMed

Phillips, Rebecca Sellin; Wheaton, Catharine J

2008-07-01

The objective of this study was to determine if sexual swellings in mandrills (Mandrillus sphinx) are a reflection of reproductive endocrine state. Urine samples were assayed using an enzyme immunoassay measuring pregnanediol-3-glucuronide (PdG) and estrone conjugates (E(1)C). Hormone patterns of ovarian cycles, pregnancy and lactation were characterized and compared with sexual swellings and copulations relative to menses and peak E(1)C. Cycle lengths averaging 28.7 days and pregnancy length of 181 days determined by hormonal and sexual swelling measures were similar to those reported in other Old World primate species. First day of copulation was observed during rising E(1)C concentrations and preceded observations of peak swelling by 1-2 days. Observations of peak sexual swellings occurred at or on the day after peak E(1)C and decreased following the ovulatory increase in PdG. Observations of menses and sexual swellings are a useful method to track mandrill ovarian cycles and can assist zoos in determining the reproductive state of females in their collections. Zoo Biol 27:320-330, 2008. (c) 2008 Wiley-Liss, Inc.

Mathematical modelling of liquid transport in swelling pharmaceutical immediate release tablets.

PubMed

Markl, Daniel; Yassin, Samy; Wilson, D Ian; Goodwin, Daniel J; Anderson, Andrew; Zeitler, J Axel

2017-06-30

Oral dosage forms are an integral part of modern health care and account for the majority of drug delivery systems. Traditionally the analysis of the dissolution behaviour of a dosage form is used as the key parameter to assess the performance of a drug product. However, understanding the mechanisms of disintegration is of critical importance to improve the quality of drug delivery systems. The disintegration performance is primarily impacted by the hydration and subsequent swelling of the powder compact. Here we compare liquid ingress and swelling data obtained using terahertz pulsed imaging (TPI) to a set of mathematical models. The interlink between hydration kinetics and swelling is described by a model based on Darcy's law and a modified swelling model based on that of Schott. Our new model includes the evolution of porosity, pore size and permeability as a function of hydration time. Results obtained from two sets of samples prepared from pure micro-crystalline cellulose (MCC) indicate a clear difference in hydration and swelling for samples of different porosities and particle sizes, which are captured by the model. Coupling a novel imaging technique, such as TPI, and mathematical models allows better understanding of hydration and swelling and eventually tablet disintegration. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

Oesophageal bioadhesion of sodium alginate suspensions: particle swelling and mucosal retention.

PubMed

Richardson, J Craig; Dettmar, Peter W; Hampson, Frank C; Melia, Colin D

2004-09-01

This paper describes a prospective bioadhesive liquid dosage form designed to specifically adhere to the oesophageal mucosa. It contains a swelling polymer, sodium alginate, suspended in a water-miscible vehicle and is activated by dilution with saliva to form an adherent layer of polymer on the mucosal surface. The swelling of alginate particles and the bioadhesion of 40% (w/w) sodium alginate suspensions were investigated in a range of vehicles: glycerol, propylene glycol, PEG 200 and PEG 400. Swelling of particles as a function of vehicle dilution with artificial saliva was quantified microscopically using 1,9-dimethyl methylene blue (DMMB) as a visualising agent. The minimum vehicle dilution to initiate swelling varied between vehicles: glycerol required 30% (w/w) dilution whereas PEG 400 required nearly 60% (w/w). Swelling commenced when the Hildebrand solubility parameter of the diluted vehicle was raised to 37 MPa(1/2). The bioadhesive properties of suspensions were examined by quantifying the amount of sodium alginate retained on oesophageal mucosa after washing in artificial saliva. Suspensions exhibited considerable mucoretention and strong correlations were obtained between mucosal retention, the minimum dilution to initiate swelling, and the vehicle Hildebrand solubility parameter. These relationships may allow predictive design of suspensions with specific mucoretentive properties, through judicious choice of vehicle characteristics.

A Coupled Thermal–Hydrological–Mechanical Damage Model and Its Numerical Simulations of Damage Evolution in APSE

PubMed Central

Wei, Chenhui; Zhu, Wancheng; Chen, Shikuo; Ranjith, Pathegama Gamage

2016-01-01

This paper proposes a coupled thermal–hydrological–mechanical damage (THMD) model for the failure process of rock, in which coupling effects such as thermally induced rock deformation, water flow-induced thermal convection, and rock deformation-induced water flow are considered. The damage is considered to be the key factor that controls the THM coupling process and the heterogeneity of rock is characterized by the Weibull distribution. Next, numerical simulations on excavation-induced damage zones in Äspö pillar stability experiments (APSE) are carried out and the impact of in situ stress conditions on damage zone distribution is analysed. Then, further numerical simulations of damage evolution at the heating stage in APSE are carried out. The impacts of in situ stress state, swelling pressure and water pressure on damage evolution at the heating stage are simulated and analysed, respectively. The simulation results indicate that (1) the v-shaped notch at the sidewall of the pillar is predominantly controlled by the in situ stress trends and magnitude; (2) at the heating stage, the existence of confining pressure can suppress the occurrence of damage, including shear damage and tensile damage; and (3) the presence of water flow and water pressure can promote the occurrence of damage, especially shear damage. PMID:28774001

Regional Wave Climates along Eastern Boundary Currents

NASA Astrophysics Data System (ADS)

Semedo, Alvaro; Soares, Pedro

2016-04-01

Two types of wind-generated gravity waves coexist at the ocean surface: wind sea and swell. Wind sea waves are waves under growing process. These young growing waves receive energy from the overlaying wind and are strongly coupled to the local wind field. Waves that propagate away from their generation area and no longer receive energy input from the local wind are called swell. Swell waves can travel long distances across entire ocean basins. A qualitative study of the ocean waves from a locally vs. remotely generation perspective is important, since the air sea interaction processes is strongly modulated by waves and vary accordingly to the prevalence of wind sea or swell waves in the area. A detailed climatology of wind sea and swell waves along eastern boundary currents (EBC; California Current, Canary Current, in the Northern Hemisphere, and Humboldt Current, Benguela Current, and Western Australia Current, in the Southern Hemisphere), based on the ECMWF (European Centre for Medium-Range Weather Forecasts) ERA-Interim reanalysis will be presented. The wind regime along EBC varies significantly from winter to summer. The high summer wind speeds along EBC generate higher locally generated wind sea waves, whereas lower winter wind speeds in these areas, along with stronger winter extratropical storms far away, lead to a predominance of swell waves there. In summer, the coast parallel winds also interact with coastal headlands, increasing the wind speed through a process called "expansion fan", which leads to an increase in the height of locally generated waves downwind of capes and points. Hence the spatial patterns of the wind sea or swell regional wave fields are shown to be different from the open ocean along EBC, due to coastal geometry and fetch dimensions. Swell waves will be shown to be considerably more prevalent and to carry more energy in winter along EBC, while in summer locally generated wind sea waves are either more comparable to swell waves or, particularly in the lee of headlands, or even more prevalent and more energized than swell. This study is part of the WRCP-JCOMM COWCLIP (Coordinated Ocean Wave Climate Project) effort.

Carbon dioxide adsorption in Brazilian coals

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

Jose Luciano Soares; Andre L.B. Oberziner; Humberto J. Jose

Carbon dioxide (CO{sub 2}) is one of the most important greenhouse gases. In the period between 1980 and 1998, CO{sub 2} emissions increased more than 21% and projections suggest that the emissions will continue to increase globally by 2.2% between 2000 and 2020 and 3.3% in the developed countries. The sequestration of CO{sub 2} in deep unminable coal beds is one of the more promising of several methods of geological sequestration that are currently being investigated. CO{sub 2} can adsorb onto coal, and there are several studies demonstrating that CO{sub 2} dissolves in coals and swells them. At very lowmore » pressures (P {lt} 1 bar), CO{sub 2} dissolution does not seem to be a problem; however, high pressures are necessary for CO{sub 2} sequestration (P {gt} 50 bar). In this study, we evaluated the kinetics and equilibrium of sorption of CO{sub 2} on Brazilian coals at low pressures. The adsorption equilibrium isotherm at room temperature (30{sup o}C) was measured through the static method. The results showed that the Freundlich model or the Langmuir model is suitable to describe the equilibrium experimental results. The CO{sub 2} adsorption capacity of Brazilian coals are in the range of 0.089-0.186 mmol CO{sub 2}/g, which are typical values for coals with high ash content. The dynamics of adsorption in a fixed-bed column that contains granular coal (particle sizes of 0.8, 2.4, and 4.8 mm) showed that the adsorption rate is fast and a mathematical model was developed to describe the CO{sub 2} dynamics of the adsorption in a fixed-bed column. The linear driving force (LDF) was used to describe the rate of adsorption and the mass-transfer constants of the LDF model (K{sub s}) are in the range of 1.0-2.0 min{sup -1}. 29 refs., 5 figs., 3 tabs.« less

Exaggerated sexual swellings and male mate choice in primates: testing the reliable indicator hypothesis in the Amboseli baboons.

PubMed

Fitzpatrick, Courtney L; Altmann, Jeanne; Alberts, Susan C

2015-06-01

The paradigm of competitive males vying to influence female mate choice has been repeatedly upheld, but, increasingly, studies also report competitive females and choosy males. One female trait that is commonly proposed to influence male mate choice is the exaggerated sexual swelling displayed by females of many Old World primate species. The reliable indicator hypothesis posits that females use the exaggerated swellings to compete for access to mates, and that the swellings advertise variation in female fitness. We tested the two main predictions of this hypothesis in a wild population of baboons ( Papio cynocephalus) . First, we examined the effect of swelling size on the probability of mate-guarding ('consortship') by the highest-ranking male and the behavior of those males that trailed consorshipts ('follower males'). Second, we asked whether a female's swelling size predicted several fitness measures. We found that high-ranking males do not prefer females with larger swellings (when controlling for cycle number and conception) and that females with larger swellings did not have higher reproductive success. Our study-the only complete test of the reliable indicator hypothesis in a primate population-rejects the idea that female baboons compete for mates by advertising heritable fitness differences. Furthermore, we found unambiguous evidence that males biased their mating decisions in favor of females who had experienced more sexual cycles since their most recent pregnancy. Thus, rather than tracking the potential differences in fitness between females, male baboons appear to track and target the potential for a given reproductive opportunity to result in fertilization.

Exaggerated sexual swellings and male mate choice in primates: testing the reliable indicator hypothesis in the Amboseli baboons

PubMed Central

Fitzpatrick, Courtney L.; Altmann, Jeanne; Alberts, Susan C.

2015-01-01

The paradigm of competitive males vying to influence female mate choice has been repeatedly upheld, but, increasingly, studies also report competitive females and choosy males. One female trait that is commonly proposed to influence male mate choice is the exaggerated sexual swelling displayed by females of many Old World primate species. The reliable indicator hypothesis posits that females use the exaggerated swellings to compete for access to mates, and that the swellings advertise variation in female fitness. We tested the two main predictions of this hypothesis in a wild population of baboons (Papio cynocephalus). First, we examined the effect of swelling size on the probability of mate-guarding (‘consortship’) by the highest-ranking male and the behavior of those males that trailed consorshipts (‘follower males’). Second, we asked whether a female’s swelling size predicted several fitness measures. We found that high-ranking males do not prefer females with larger swellings (when controlling for cycle number and conception) and that females with larger swellings did not have higher reproductive success. Our study—the only complete test of the reliable indicator hypothesis in a primate population—rejects the idea that female baboons compete for mates by advertising heritable fitness differences. Furthermore, we found unambiguous evidence that males biased their mating decisions in favor of females who had experienced more sexual cycles since their most recent pregnancy. Thus, rather than tracking the potential differences in fitness between females, male baboons appear to track and target the potential for a given reproductive opportunity to result in fertilization. PMID:26752790

Studies on Poly(propylene fumarate-co-caprolactone diol) Thermoset Composites towards the Development of Biodegradable Bone Fixation Devices

PubMed Central

Jayabalan, M.

2009-01-01

The effect of reinforcement in the cross-linked poly(propylene fumarate-co-caprolactone diol) thermoset composites based on Kevlar fibres and hydroxyapatite was studied. Cross-linked poly(propylene fumarate-co-caprolactone diol) was also studied without any reinforcement for comparison. The reinforcing fibre acts as a barrier for the curing reaction leading to longer setting time and lesser cross-link density. The fibre and HA reinforced composites have almost the same compressive strength. Nonreinforced material undergoes greater degree of swelling. Among the reinforced materials, the hydroxyapatite reinforced composite has a much higher swelling percentage than the fibre reinforced one. The studies on in vitro degradation of the cured materials reveal hydrolytic degradation in Ringer's solution and PBS medium during aging. All the three materials are found to swell initially in Ringer's solution and PBS medium during aging and then undergo gradual degradation. Compression properties of these cross-linked composites increase with aging; HA reinforced composite has the highest compressive strength and compressive modulus, whereas the aged fibre-reinforced composite has the least compressive strength and modulus. PMID:20126578