Science.gov

Sample records for acetate-polyacrylamide gels maintained

  1. Simultaneous electrophoretic analysis of proteins of very high and low molecular mass using Tris-acetate polyacrylamide gels.

    PubMed

    Cubillos-Rojas, Monica; Amair-Pinedo, Fabiola; Tato, Irantzu; Bartrons, Ramon; Ventura, Francesc; Rosa, Jose Luis

    2010-04-01

    To separate and analyze giant and small proteins in the same electrophoresis gel, we have used a 3-15% polyacrylamide gradient gel containing 2.6% of the crosslinker bisacrylamide and 0.2 M of Tris-acetate buffer (pH 7.0). Samples were prepared in a sample buffer containing lithium dodecyl sulphate and were run in the gel described above using Tris-Tricine-SDS-sodium bisulfite buffer, pH 8.2, as electrophoresis buffer. Here, we show that this system can be successfully used for general applications of SDS-PAGE such as CBB staining and immunoblot. Thus, by using Tris-acetate 3-15% polyacrylamide gels, it is possible to simultaneously analyze proteins, in the mass range of 10-500 kDa, such as HERC1 (532 kDa), HERC2 (528 kDa), mTOR (289 kDa), Clathrin heavy chain (192 kDa), RSK (90 kDa), S6K (70 kDa), beta-actin (42 kDa), Ran (24 kDa) and LC3 (18 kDa). This system is highly sensitive since it allows detection from as low as 10 microg of total protein per lane. Moreover, it has a good resolution, low cost, high reproducibility and allows for analysis of proteins in a wide range of weights within a short period of time. All these features together with the use of a standard electrophoresis apparatus make the Tris-acetate-PAGE system a very helpful tool for protein analysis. PMID:20309890

  2. Fluid diversion and sweep improvement with chemical gels in oil recovery processes. [Four types of gels: resorcinol-formaldehyde; colloidal silica; Cr sup 3+ (chloride)-xanthan; and Cr sup 3+ (acetate)-polyacrylamide

    SciTech Connect

    Seright, R.S.; Martin, F.D.

    1992-09-01

    The objectives of this project were to identify the mechanisms by which gel treatments divert fluids in reservoirs and to establish where and how gel treatments are best applied. Several different types of gelants were examined, including polymer-based gelants, a monomer-based gelant, and a colloidal-silica gelant. This research was directed at gel applications in water injection wells, in production wells, and in high-pressure gas floods. The work examined how the flow properties of gels and gelling agents are influenced by permeability, lithology, and wettability. Other goals included determining the proper placement of gelants, the stability of in-place gels, and the types of gels required for the various oil recovery processes and for different scales of reservoir heterogeneity. During this three-year project, a number of theoretical analyses were performed to determine where gel treatments are expected to work best and where they are not expected to be effective. The most important, predictions from these analyses are presented. Undoubtedly, some of these predictions will be controversial. However, they do provide a starting point in establishing guidelines for the selection of field candidates for gel treatments. A logical next step is to seek field data that either confirm or contradict these predictions. The experimental work focused on four types of gels: (1) resorcinol-formaldehyde, (2) colloidal silica, (3) Cr{sup 3+}(chloride)-xanthan, and (4) Cr{sup 3+}(acetate)-polyacrylamide. All experiments were performed at 41{degrees}C.

  3. Novel edible coating based on aloe vera gel to maintain table grape quality and safety.

    PubMed

    Valverde, Juan Miguel; Valero, Daniel; Martínez-Romero, Domingo; Guillén, Fabián; Castillo, Salvador; Serrano, María

    2005-10-01

    A novel edible coating based on Aloe vera gel obtained according to SP Patent Filed 200302937 has been used as a means of preservation to maintain the quality and safety of cv. Crimson Seedless table grapes during cold storage and subsequent shelf life. Table grapes have a crucial economic value as a dessert fruit, but once harvested show a reduction of shelf life due to a rapid loss of quality. Uncoated clusters showed a rapid deterioration with an estimated shelf life period of 7 days at 1 degrees C plus 4 days at 20 degrees C, based on the fast weight loss, color changes, accelerated softening and ripening, rachis browning, and high incidence of berry decay. On the contrary, those clusters treated with A. vera gel significantly delayed the above parameters related to postharvest quality losses, and storability could be extended up to 35 days at 1 degrees C. Interestingly, this edible coating was able to reduce the initial microbial counts for both mesophillic aerobic and yeast and molds, which significantly increased in uncoated berries over storage. Moreover, the sensory analyses revealed beneficial effects in terms of delaying rachis browning and dehydration and maintenance of the visual aspect of the berry without any detrimental effect on taste, aroma, or flavors. To the authors' knowledge, this is the first time A. vera gel has been used as an edible coating in fruits, which would be an innovative and interesting means for commercial application and an alternative to the use of postharvest chemical treatments. PMID:16190634

  4. Fluid diversion and sweep improvement with chemical gels in oil recovery processes. Final report

    SciTech Connect

    Seright, R.S.; Martin, F.D.

    1992-09-01

    The objectives of this project were to identify the mechanisms by which gel treatments divert fluids in reservoirs and to establish where and how gel treatments are best applied. Several different types of gelants were examined, including polymer-based gelants, a monomer-based gelant, and a colloidal-silica gelant. This research was directed at gel applications in water injection wells, in production wells, and in high-pressure gas floods. The work examined how the flow properties of gels and gelling agents are influenced by permeability, lithology, and wettability. Other goals included determining the proper placement of gelants, the stability of in-place gels, and the types of gels required for the various oil recovery processes and for different scales of reservoir heterogeneity. During this three-year project, a number of theoretical analyses were performed to determine where gel treatments are expected to work best and where they are not expected to be effective. The most important, predictions from these analyses are presented. Undoubtedly, some of these predictions will be controversial. However, they do provide a starting point in establishing guidelines for the selection of field candidates for gel treatments. A logical next step is to seek field data that either confirm or contradict these predictions. The experimental work focused on four types of gels: (1) resorcinol-formaldehyde, (2) colloidal silica, (3) Cr{sup 3+}(chloride)-xanthan, and (4) Cr{sup 3+}(acetate)-polyacrylamide. All experiments were performed at 41{degrees}C.

  5. BST-CarGel® Treatment Maintains Cartilage Repair Superiority over Microfracture at 5 Years in a Multicenter Randomized Controlled Trial

    PubMed Central

    Stanish, William D.; McCormack, Robert; Forriol, Francisco; Mohtadi, Nicholas; Pelet, Stéphane; Desnoyers, Jacques; Méthot, Stéphane; Vehik, Kendra; Restrepo, Alberto

    2015-01-01

    Objective The efficacy and safety of BST-CarGel®, a chitosan scaffold for cartilage repair was compared with microfracture alone at 1 year during a multicenter randomized controlled trial in the knee. This report was undertaken to investigate 5-year structural and clinical outcomes. Design The international randomized controlled trial enrolled 80 patients, aged 18 to 55 years, with grade III or IV focal lesions on the femoral condyles. Patients were randomized to receive BST-CarGel® treatment or microfracture alone, and followed standardized 12-week rehabilitation. Co-primary endpoints of repair tissue quantity and quality were evaluated by 3-dimensional MRI quantification of the degree of lesion filling (%) and T2 relaxation times. Secondary endpoints were clinical benefit measured with WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) questionnaires and safety. General estimating equations were used for longitudinal statistical analysis of repeated measures. Results Blinded MRI analysis demonstrated that BST-CarGel®-treated patients showed a significantly greater treatment effect for lesion filling (P = 0.017) over 5 years compared with microfracture alone. A significantly greater treatment effect for BST-CarGel® was also found for repair tissue T2 relaxation times (P = 0.026), which were closer to native cartilage compared to the microfracture group. BST-CarGel® and microfracture groups showed highly significant improvement at 5 years from pretreatment baseline for each WOMAC subscale (P < 0.0001), and there were no differences between the treatment groups. Safety was comparable for both groups. Conclusions BST-CarGel® was shown to be an effective mid-term cartilage repair treatment. At 5 years, BST-CarGel® treatment resulted in sustained and significantly superior repair tissue quantity and quality over microfracture alone. Clinical benefit following BST-CarGel® and microfracture treatment were highly significant over baseline

  6. COUPLING THE ALKALINE-SURFACTANT-POLYMER TECHNOLOGY AND THE GELATION TECHNOLOGY TO MAXIMIZE OIL PRODUCTION

    SciTech Connect

    Malcolm Pitts; Jie Qi; Dan Wilson

    2004-10-01

    Gelation technologies have been developed to provide more efficient vertical sweep efficiencies for flooding naturally fractured oil reservoirs or more efficient areal sweep efficiency for those with high permeability contrast ''thief zones''. The field proven alkaline-surfactant-polymer technology economically recovers 15% to 25% OOIP more oil than waterflooding from swept pore space of an oil reservoir. However, alkaline-surfactant-polymer technology is not amenable to naturally fractured reservoirs or those with thief zones because much of injected solution bypasses target pore space containing oil. This work investigates whether combining these two technologies could broaden applicability of alkaline-surfactant-polymer flooding into these reservoirs. A prior fluid-fluid report discussed interaction of different gel chemical compositions and alkaline-surfactant-polymer solutions. Gel solutions under dynamic conditions of linear corefloods showed similar stability to alkaline-surfactant-polymer solutions as in the fluid-fluid analyses. Aluminum-polyacrylamide, flowing gels are not stable to alkaline-surfactant-polymer solutions of either pH 10.5 or 12.9. Chromium acetate-polyacrylamide flowing and rigid flowing gels are stable to subsequent alkaline-surfactant-polymer solution injection. Rigid flowing chromium acetate-polyacrylamide gels maintained permeability reduction better than flowing chromium acetate-polyacrylamide gels. Silicate-polyacrylamide gels are not stable with subsequent injection of either a pH 10.5 or a 12.9 alkaline-surfactant-polymer solution. Neither aluminum citrate-polyacrylamide nor silicate-polyacrylamide gel systems produced significant incremental oil in linear corefloods. Both flowing and rigid flowing chromium acetate-polyacrylamide gels produced incremental oil with the rigid flowing gel producing the greatest amount. Higher oil recovery could have been due to higher differential pressures across cores. None of the gels tested

  7. Conformance Improvement Using Gels

    SciTech Connect

    Seright, Randall S.; Schrader, Richard; II Hagstrom, John; Wang, Ying; Al-Dahfeeri, Abdullah; Gary, Raven; Marin; Amaury; Lindquist, Brent

    2002-09-26

    This research project had two objectives. The first objective was to identify gel compositions and conditions that substantially reduce flow through fractures that allow direct channeling between wells, while leaving secondary fractures open so that high fluid injection and production rates can be maintained. The second objective was to optimize treatments in fractured production wells, where the gel must reduce permeability to water much more than that to oil.

  8. CONFORMANCE IMPROVEMENT USING GELS

    SciTech Connect

    Randall S. Seright

    2003-09-01

    This report describes work performed during the second year of the project, ''Conformance Improvement Using Gels.'' The project has two objectives. The first objective is to identify gel compositions and conditions that substantially reduce flow through fractures that allow direct channeling between wells, while leaving secondary fractures open so that high fluid injection and production rates can be maintained. The second objective is to optimize treatments in fractured production wells, where the gel must reduce permeability to water much more than that to oil. Pore-level images from X-ray computed microtomography were re-examined for Berea sandstone and porous polyethylene. This analysis suggests that oil penetration through gel-filled pores occurs by a gel-dehydration mechanism, rather than a gel-ripping mechanism. This finding helps to explain why aqueous gels can reduce permeability to water more than to oil. We analyzed a Cr(III)-acetate-HPAM gel treatment in a production well in the Arbuckle formation. The availability of accurate pressure data before, during, and after the treatment was critical for the analysis. After the gel treatment, water productivity was fairly constant at about 20% of the pre-treatment value. However, oil productivity was stimulated by a factor of 18 immediately after the treatment. During the six months after the treatment, oil productivity gradually decreased to approach the pre-treatment value. To explain this behavior, we proposed that the fracture area open to oil flow was increased substantially by the gel treatment, followed by a gradual closing of the fractures during subsequent production. For a conventional Cr(III)-acetate-HPAM gel, the delay between gelant preparation and injection into a fracture impacts the placement, leakoff, and permeability reduction behavior. Formulations placed as partially formed gels showed relatively low pressure gradients during placement, and yet substantially reduced the flow capacity of

  9. Polyelectrolyte gels

    SciTech Connect

    Segalman, D.J.; Witkowski, W.R.

    1995-06-01

    Polyelectrolyte (PE) gels are swollen polymer/solvent networks that undergo a reversible volume collapse/expansion through various types of stimulation. Applications that could exploit this large deformation and solvent expulsion/absorption characteristics include robotic {open_quotes}fingers{close_quotes} and drug delivery systems. The goals of the research were to first explore the feasibility of using the PE gels as {open_quotes}smart materials{close_quotes} - materials whose response can be controlled by an external stimulus through a feedback mechanism. Then develop a predictive capability to simulate the dynamic behavior of these gels. This involved experimentally characterizing the response of well-characterized gels to an applied electric field and other stimuli to develop an understanding of the underlying mechanisms which cause the volume collapse. Lastly, the numerical analysis tool was used to simulate various potential engineering devices based on PE gels. This report discusses the pursuit of those goals through experimental and computational means.

  10. Adhesive, elastomeric gel impregnating composition

    DOEpatents

    Shaw, David Glenn; Pollard, John Randolph; Brooks, Robert Aubrey

    2002-01-01

    An improved capacitor roll with alternating film and foil layers is impregnated with an adhesive, elastomeric gel composition. The gel composition is a blend of a plasticizer, a polyol, a maleic anhydride that reacts with the polyol to form a polyester, and a catalyst for the reaction. The impregnant composition is introduced to the film and foil layers while still in a liquid form and then pressure is applied to aid with impregnation. The impregnant composition is cured to form the adhesive, elastomeric gel. Pressure is maintained during curing.

  11. COUPLING THE ALKALINE-SURFACTANT-POLYMER TECHNOLOGY AND THE GELATION TECHNOLOGY TO MAXIMIZE OIL PRODUCTION

    SciTech Connect

    Malcolm Pitts; Jie Qi; Dan Wilson; David Stewart; Bill Jones

    2005-04-01

    Gelation technologies have been developed to provide more efficient vertical sweep efficiencies for flooding naturally fractured oil reservoirs or more efficient areal sweep efficiency for those with high permeability contrast ''thief zones''. The field proven alkaline-surfactant-polymer technology economically recovers 15% to 25% OOIP more oil than waterflooding from swept pore space of an oil reservoir. However, alkaline-surfactant-polymer technology is not amenable to naturally fractured reservoirs or those with thief zones because much of injected solution bypasses target pore space containing oil. This work investigates whether combining these two technologies could broaden applicability of alkaline-surfactant-polymer flooding into these reservoirs. A prior fluid-fluid report discussed interaction of different gel chemical compositions and alkaline-surfactant-polymer solutions. Gel solutions under dynamic conditions of linear corefloods showed similar stability to alkaline-surfactant-polymer solutions as in the fluid-fluid analyses. Aluminum-polyacrylamide, flowing gels are not stable to alkaline-surfactant-polymer solutions of either pH 10.5 or 12.9. Chromium acetate-polyacrylamide flowing and rigid flowing gels are stable to subsequent alkaline-surfactant-polymer solution injection. Rigid flowing chromium acetate-polyacrylamide gels maintained permeability reduction better than flowing chromium acetate-polyacrylamide gels. Silicate-polyacrylamide gels are not stable with subsequent injection of either a pH 10.5 or a 12.9 alkaline-surfactant-polymer solution. Chromium acetate-xanthan gum rigid gels are not stable to subsequent alkaline-surfactant-polymer solution injection. Resorcinol-formaldehyde gels were stable to subsequent alkaline-surfactant-polymer solution injection. When evaluated in a dual core configuration, injected fluid flows into the core with the greatest effective permeability to the injected fluid. The same gel stability trends to subsequent

  12. Rheology of Active Gels

    NASA Astrophysics Data System (ADS)

    Chen, Daniel

    2015-03-01

    Active networks drive a diverse range of critical processes ranging from motility to division in living cells, yet a full picture of their rheological capabilities in non-cellular contexts is still emerging, e.g., How does the rheological response of a network capable of remodeling under internally-generated stresses differ from that of a passive biopolymer network? In order to address this and other basic questions, we have engineered an active gel composed of microtubules, bidirectional kinesin motors, and molecular depletant that self-organizes into a highly dynamic network of active bundles. The network continually remodels itself under ATP-tunable cycles of extension, buckling, fracturing, and self-healing. Using confocal rheometry we have simultaneously characterized the network's linear and non-linear rheological responses to shear deformation along with its dynamic morphology. We find several surprising and unique material properties for these active gels; most notably, rheological cloaking, the ability of the active gel to drive large-scale fluid mixing over several orders of flow magnitude while maintaining an invariant, solid-like rheological profile and spontaneous flow under confinement, the ability to exert micro-Newton forces to drive persistent directed motion of the rheometer tool. Taken together, these results and others to be discussed highlight the rich stress-structure-dynamics relationships in this class of biologically-derived active gels.

  13. Aerosol gels

    NASA Technical Reports Server (NTRS)

    Sorensen, Christopher M. (Inventor); Chakrabarti, Amitabha (Inventor); Dhaubhadel, Rajan (Inventor); Gerving, Corey (Inventor)

    2010-01-01

    An improved process for the production of ultralow density, high specific surface area gel products is provided which comprises providing, in an enclosed chamber, a mixture made up of small particles of material suspended in gas; the particles are then caused to aggregate in the chamber to form ramified fractal aggregate gels. The particles should have a radius (a) of up to about 50 nm and the aerosol should have a volume fraction (f.sub.v) of at least 10.sup.-4. In preferred practice, the mixture is created by a spark-induced explosion of a precursor material (e.g., a hydrocarbon) and oxygen within the chamber. New compositions of matter are disclosed having densities below 3.0 mg/cc.

  14. Tissue simulating gel for medical research

    NASA Technical Reports Server (NTRS)

    Companion, John A. (Inventor)

    1991-01-01

    A tissue simulating gel and a method for preparing the tissue simulating gel are disclosed. The tissue simulating gel is prepared by a process using water, gelatin, ethylene glycol, and a cross-linking agent. In order to closely approximate the characteristics of the type of tissue being simulated, other material has been added to change the electrical, sound conducting, and wave scattering properties of the tissue simulating gel. The result of the entire process is a formulation that will not melt at the elevated temperatures involved in hyperthermia medical research. Furthermore, the tissue simulating gel will not support mold or bacterial growth, is of a sufficient mechanical strength to maintain a desired shape without a supporting shell, and is non-hardening and non-drying. Substances have been injected into the tissue simulating gel prior to the setting-up thereof just as they could be injected into actual tissue, and the tissue simulating gel is translucent so as to permit visual inspection of its interior. A polyurethane spray often used for coating circuit boards can be applied to the surface of the tissue simulating gel to give a texture similar to human skin, making the tissue simulating gel easier to handle and contributing to its longevity.

  15. Maintaining Medicinal Plant Germplasm

    Technology Transfer Automated Retrieval System (TEKTRAN)

    For all plant genetic resources collections, including medicinal plant germplasm, maintaining the genetic integrity of material held ex situ is of major importance. This holds true for all intended end uses of the material whether it is as a source for crop improvement, medical research, as voucher...

  16. Maintaining Your Health

    MedlinePlus

    ... center but can also be done in nursing facilities, hospitals, or at home. Book a PFF Ambassador for your event. Call 844.TalkPFF > Life with PF About PF Treatment Options Clinical Trials Maintaining Your Health Find Medical Care Support Groups PFF ...

  17. Fundamentals of gel dosimeters

    NASA Astrophysics Data System (ADS)

    McAuley, K. B.; Nasr, A. T.

    2013-06-01

    Fundamental chemical and physical phenomena that occur in Fricke gel dosimeters, polymer gel dosimeters, micelle gel dosimeters and genipin gel dosimeters are discussed. Fricke gel dosimeters are effective even though their radiation sensitivity depends on oxygen concentration. Oxygen contamination can cause severe problems in polymer gel dosimeters, even when THPC is used. Oxygen leakage must be prevented between manufacturing and irradiation of polymer gels, and internal calibration methods should be used so that contamination problems can be detected. Micelle gel dosimeters are promising due to their favourable diffusion properties. The introduction of micelles to gel dosimetry may open up new areas of dosimetry research wherein a range of water-insoluble radiochromic materials can be explored as reporter molecules.

  18. Nuclear power plant maintainability.

    PubMed

    Seminara, J L; Parsons, S O

    1982-09-01

    In the mid-1970s a general awareness of human factors engineering deficiencies associated with power plant control rooms took shape and the Electric Power Research Institute (EPRI) awarded the Lockheed Corporation a contract to review the human factors aspects of five representative operational control rooms and their associated simulators. This investigation revealed a host of major and minor deficiencies that assumed unforeseen dimensions in the post- Three Mile Island accident period. In the course of examining operational problems (Seminara et al, 1976) and subsequently the methods for overcoming such problems (Seminara et al, 1979, 1980) indications surfaced that power plants were far from ideal in meeting the needs of maintenance personnel. Accordingly, EPRI sponsored an investigation of the human factors aspects of power plant maintainability (Seminara, 1981). This paper provides an overview of the maintainability problems and issues encountered in the course of reviewing five nuclear power plants. PMID:15676441

  19. Obtaining and maintaining funding

    SciTech Connect

    Beverly Hartline

    1996-04-01

    Obtaining and maintaining funding is important for individuals, groups, institutions, and fields. This challenge is easier during times of abundant and growing resources than it is now, when funding is tight and shrinking. Thus, to obtain and maintain funding will require: maintaining healthy funding levels for all of science; maintaining healthy funding levels for the field(s) you work in; and competing successfully for the available funds. Everyone should pay attention to the overall prospects for science funding and dedicate some effort to working with others to grow the constituency for science. Public support is likely an important prerequisite for keeping future science budgets high. In this context, researchers should share with society at large the benefits of their research, so that taxpayers can see and appreciate some return from the federal investment in science. Assuming this effort is successful, and there continue to be government and private organizations with substantial resources to invest in research, what can the individual investigator do to improve her chances? She can be clear about her goal(s) and carefully plan her effort to make maximum progress for minimum resources, especially early in her career while she is establishing a solid professional reputation. Specific useful strategies include: brainstorm funding options and select the most promising one(s); be persistent but flexible, responsive to new information and changing circumstances; provide value and assistance to prospective funding sources both before and after receiving funding; know the funding agents and what their goals are, they are the customers; promise a lot and always deliver more; build partnerships and collaboration to leverage interest and resources; and develop capabilities and ideas with a promising, irresistible future. There is no guarantee of success. For the best chances, consistently contribute positively and productively in all your efforts, and continue to

  20. Maintaining radiation protection records

    SciTech Connect

    Not Available

    1992-11-30

    This Report is part of a series prepared under the auspices of Scientific Committee 46 on Operational Radiation Safety. It provides guidance on maintaining radiation protection records. Record keeping is an essential element of every radiation protection program. This Report describes the elements that should enter into the design of a program for the maintenance of operational radiation safety records. The problems of the length of time for retention of records for operational, regulatory, epidemiologic and legal uses are discussed in detail.

  1. Coupling the Alkaline-Surfactant-Polymer Technology and The Gelation Technology to Maximize Oil Production

    SciTech Connect

    Malcolm Pitts; Jie Qi; Dan Wilson; Phil Dowling; David Stewart; Bill Jones

    2005-12-01

    the fluid-fluid analyses with the exception of the xanthan gum-chromium acetate gels. Aluminum-polyacrylamide flowing gels are not stable to alkaline-surfactant-polymer solutions of either pH 10.5 or 12.9, either in linear corefloods or in dual separate radial core, common manifold corefloods. Chromium acetate-polyacrylamide flowing and rigid tonguing gels are stable to subsequent alkaline-surfactant-polymer solution injection. Rigid tonguing chromium acetate-polyacrylamide gels maintained permeability reduction better than flowing chromium acetate-polyacrylamide gels. Chromium acetate gels were stable to injection of alkaline-surfactant-polymer solutions at 72 F, 125 F and 175 F in linear corefloods. Chromium acetate-polyacrylamide gels maintained diversion capability after injection of an alkaline-surfactant-polymer solution in stacked; radial coreflood with a common well bore. Chromium acetate-polyacrylamide gel used to seal fractured core maintain fracture closure if followed by an alkaline-surfactant-polymer solution. Chromium acetatexanthan gum rigid gels are not stable to subsequent alkaline-surfactant-polymer solution injection at 72, 125, and 175 F. Silicate-polyacrylamide gels are not stable with subsequent injection of either a pH 10.5 or a 12.9 alkaline-surfactant-polymer solution. Resorcinol-formaldehyde gels were stable to subsequent alkaline-surfactant-polymer solution injection. When evaluated in a dual core configuration, injected fluid flows into the core with the greatest effective permeability to the injected fluid. The same gel stability trends to subsequent alkaline-surfactant-polymer injected solution were observed. Aluminum citrate-polyacrylamide, resorcinol-formaldehyde, and the silicate-polyacrylamide gel systems did not produce significant incremental oil in linear corefloods. Both flowing and rigid tonguing chromium acetate-polyacrylamide gels and the xanthan gum-chromium acetate gel system produced incremental oil with the rigid tonguing

  2. Coupling the Alkaline-Surfactant-Polymer Technology and the Gelation Technology to Maximize Oil Production

    SciTech Connect

    Malcolm Pitts; Jie Qi; Dan Wilson; Phil Dowling; David Stewart; Bill Jones

    2005-12-01

    the fluid-fluid analyses with the exception of the xanthan gum-chromium acetate gels. Aluminum-polyacrylamide flowing gels are not stable to alkaline-surfactant-polymer solutions of either pH 10.5 or 12.9, either in linear corefloods or in dual separate radial core, common manifold corefloods. Chromium acetate-polyacrylamide flowing and rigid tonguing gels are stable to subsequent alkaline-surfactant-polymer solution injection. Rigid tonguing chromium acetate-polyacrylamide gels maintained permeability reduction better than flowing chromium acetate-polyacrylamide gels. Chromium acetate gels were stable to injection of alkaline-surfactant-polymer solutions at 72 F, 125 F and 175 F in linear corefloods. Chromium acetate-polyacrylamide gels maintained diversion capability after injection of an alkaline-surfactant-polymer solution in stacked; radial coreflood with a common well bore. Chromium acetate-polyacrylamide gel used to seal fractured core maintain fracture closure if followed by an alkaline-surfactant-polymer solution. Chromium acetate-xanthan gum rigid gels are not stable to subsequent alkaline-surfactant-polymer solution injection at 72, 125, and 175 F. Silicate-polyacrylamide gels are not stable with subsequent injection of either a pH 10.5 or a 12.9 alkaline-surfactant-polymer solution. Resorcinol-formaldehyde gels were stable to subsequent alkaline-surfactant-polymer solution injection. When evaluated in a dual core configuration, injected fluid flows into the core with the greatest effective permeability to the injected fluid. The same gel stability trends to subsequent alkaline-surfactant-polymer injected solution were observed. Aluminum citrate-polyacrylamide, resorcinol-formaldehyde, and the silicate-polyacrylamide gel systems did not produce significant incremental oil in linear corefloods. Both flowing and rigid tonguing chromium acetate-polyacrylamide gels and the xanthan gum-chromium acetate gel system produced incremental oil with the rigid tonguing

  3. Testosterone Nasal Gel

    MedlinePlus

    Testosterone nasal gel is used to treat symptoms of low testosterone in men who have hypogonadism (a condition in which the body does not produce enough natural testosterone). Testosterone nasal gel is used only for men ...

  4. Gel pad application for automated breast sonography.

    PubMed

    Kim, Yun Ju; Kim, Sung Hun; Jeh, Su Kyung; Choi, Jae Jeong; Kang, Bong Joo; Song, Byung Joo

    2015-04-01

    The purpose of this study was to describe the technical aspects of gel pad application for automated breast sonography and to show its effects on pain relief, scan coverage, and image quality. Twenty patients underwent 2 sets of automated breast sonography with and without gel pad application and were then asked to provide feedback on the examination-related pain. Scan coverage and image quality were compared quantitatively and qualitatively. The degree of pain was significantly decreased after gel pad application (P < .0001). The scan coverage was expanded particularly at the mid-portion of the breast. Image quality was satisfactory without significant differences between the sets. Gel pad application for automated breast sonography is easy and provides significant pain relief. The scan coverage was expanded, while the image quality was maintained. PMID:25792588

  5. Improving immobilized biocatalysts by gel phase polymerization

    SciTech Connect

    Kuu, W.Y.; Polack, J.A.

    1983-08-01

    A new method is presented for the treatment of gel-type supports, used for immobilizing microbial cells and enzymes, to obtain high mechanical strength. It is particularly useful for ethanol fermentation over gel beads containing immobilized viable cells, where the beads can be ruptured by gas production and the growth of cells within the gels. This method consists of treating agar or carrageenan gel with polyacrylamide to form a rigid support which retains the high catalytic activity characteristic of the untreated biocatalysts. The size and shape of the biocatalyst is unaffected by this treatment. The method involves the diffusion of acrylamide, N,N'-methylenebisacrylamide and ..beta..-dimethylaminopropionitrile (or N,N,N',N'-tetramethylethylenediamine) into the preformed biocatalyst beads followed by the addition of an initiator to cause polymerization within the beads. Treated gels have been used for the continuous fermentation of glucose to ethanol in a packed column for over two months. During this operation, the gel beads maintained their rigidity, and the maximum productivity was as high as 50 gh/sup -1/ L/sup -1/ gel. There was no appreciable decay of cell activity.

  6. Maintaining gas cooling equipment

    SciTech Connect

    Rector, J.D.

    1997-05-01

    An often overlooked key to satisfactory operation and longevity of any mechanical device is proper operation and maintenance in accordance with the manufacturer`s written instructions. Absorption chillers, although they use a different technology than the more familiar vapor compression cycle to produce chilled water, operate successfully in a variety of applications if operated and maintained properly. Maintenance procedures may be more frequent than those required for vapor compression chillers, but they are also typically less complex. The goal of this article is to describe the basic operation of an absorption chiller to provide an understanding of the relatively simple tasks required to keep the machine operating at maximum efficiency for its design life and beyond. A good starting point is definitions. Gas cooling equipment is generally defined as alternative energy, non-electric cooling products. This includes absorption chillers, engine-drive chillers and packaged desiccant units, among others. Natural gas combustion drives the equipment.

  7. Reagan: Maintain Antarctic program

    NASA Astrophysics Data System (ADS)

    Richman, Barbara T.

    President Ronald Reagan has decided that the United States should maintain an ‘active and influential presence’ in Antarctica to support the nation's interests. Following a review of a study by the Antarctica Policy Group, Reagan issued a memorandum, dated February 5, to the heads of 14 government agencies, including the National Science Foundation (NSF), the Office of Science and Technology Policy, and the Office of Management and Budget.The U.S. presence in Antarctica ‘shall include the conduct of scientific activities in major disciplines; year-round occupation of the South Pole and two coastal stations; and availability of related necessary logistics support,’ wrote the President. In addition, NSF should continue to budget for the entire U.S. program in Antarctica. Short-term programs by other agencies require the recommendation of the Antarctica Policy Group and should be coordinated within the framework of NSF logistics support.

  8. Genipin-crosslinked chitosan/poly-L-lysine gels promote fibroblast adhesion and proliferation.

    PubMed

    Mekhail, Mina; Jahan, Kaushar; Tabrizian, Maryam

    2014-08-01

    Chitosan blends have been widely investigated to create biomaterials with desirable physicochemical and biological properties for tissue engineering applications. A recurring difficulty, however, has been to maintain their stability in an aqueous environment. The rationale behind this study was to demonstrate that genipin crosslinking can improve and maintain the stability of chitosan/poly-l-lysine (PLL) blends. Four gel formulations were prepared by varying the weight ratios of chitosan and PLL. Electron microscopy revealed that genipin crosslinking provided a more homogenous gel surface compared to uncrosslinked gels. Moreover, it was discovered that 3h was sufficient to stabilize the gels. In vitro studies using fibroblasts demonstrated that genipin-crosslinked gels enhanced fibroblasts' attachment as compared to uncrosslinked gels. Moreover, cell viability was significantly improved by 1.6 times on 60:40 gels, and 6.5 times on 50:50 gels after crosslinking. Finally, proliferation was enhanced up to 5 times on 60:40 gels. PMID:24751251

  9. Maintaining proper dental records.

    PubMed

    Leeuw, Wilhemina

    2014-01-01

    Referred to as Standard of Care, the legal duty of a dentist requires exercising the degree of skill and care that would be exhibited by other prudent dentists faced with the same patient-care situation. Primarily, the goal of keeping good dental records is to maintain continuity of care. Diligent and complete documentation and charting procedures are essential to fulfilling the Standard of Care. Secondly, because dental records are considered legal documents they help protect the interest of the dentist and/or the patient by establishing the details of the services rendered. Patients today are better educated and more assertive than ever before and dentists must be equipped to protect themselves against malpractice claims. Every record component must be handled as if it could be summoned to a court room and scrutinized by an attorney, judge or jury. Complete, accurate, objective and honest entries in a patient record are the only way to defend against any clinical and/or legal problems that might arise. Most medical and dental malpractice claims arise from an unfavorable interaction with the dentist and not from a poor treatment outcome. By implementing the suggestions mentioned in this course, dental health care professionals can minimize the legal risks associated with the delivery of dental care to promote greater understanding for patients of their rights and privileges to their complete record. PMID:24834675

  10. Sol-Gel Glasses

    NASA Technical Reports Server (NTRS)

    Mukherjee, S. P.

    1985-01-01

    Multicomponent homogeneous, ultrapure noncrystalline gels/gel derived glasses are promising batch materials for the containerless glass melting experiments in microgravity. Hence, ultrapure, homogeneous gel precursors could be used to: (1) investigate the effect of the container induced nucleation on the glass forming ability of marginally glass forming compositions; and (2) investigate the influence of gravity on the phase separation and coarsening behavior of gel derived glasses in the liquid-liquid immiscibility zone of the nonsilicate systems having a high density phase. The structure and crystallization behavior of gels in the SiO2-GeO2 as a function of gel chemistry and thermal treatment were investigated. As are the chemical principles involved in the distribution of a second network former in silica gel matrix being investigated. The procedures for synthesizing noncrystalline gels/gel-monoliths in the SiO2-GeO2, GeO2-PbO systems were developed. Preliminary investigations on the levitation and thermal treatment of germania silicate gel-monoliths in the Pressure Facility Acoustic Levitator were done.

  11. ADAS Update and Maintainability

    NASA Technical Reports Server (NTRS)

    Watson, Leela R.

    2010-01-01

    Since 2000, both the National Weather Service Melbourne (NWS MLB) and the Spaceflight Meteorology Group (SMG) have used a local data integration system (LOIS) as part of their forecast and warning operations. The original LOIS was developed by the Applied Meteorology Unit (AMU) in 1998 (Manobianco and Case 1998) and has undergone subsequent improvements. Each has benefited from three-dimensional (3-D) analyses that are delivered to forecasters every 15 minutes across the peninsula of Florida. The intent is to generate products that enhance short-range weather forecasts issued in support of NWS MLB and SMG operational requirements within East Central Florida. The current LDIS uses the Advanced Regional Prediction System (ARPS) Data Analysis System (AD AS) package as its core, which integrates a wide variety of national, regional, and local observational data sets. It assimilates all available real-time data within its domain and is run at a finer spatial and temporal resolution than current national or regional-scale analysis packages. As such, it provides local forecasters with a more comprehensive understanding of evolving fine-scale weather features. Over the years, the LDIS has become problematic to maintain since it depends on AMU-developed shell scripts that were written for an earlier version of the ADAS software. The goals of this task were to update the NWS MLB/SMG LDIS with the latest version of ADAS, incorporate new sources of observational data, and upgrade and modify the AMU-developed shell scripts written to govern the system. In addition, the previously developed ADAS graphical user interface (GUI) was updated. Operationally, these upgrades will result in more accurate depictions of the current local environment to help with short-range weather forecasting applications, while also offering an improved initialization for local versions of the Weather Research and Forecasting (WRF) model used by both groups.

  12. Maintaining the unmethylated state

    PubMed Central

    2013-01-01

    Background A remarkable correspondence exists between the cytogenetic locations of the known fragile sites and frequently reported sites of hypermethylation. The best-known features of fragile sites are sequence motifs that are prone to the spontaneous formation of a non-B DNA structure. These facts, coupled with the known enzymological specificities of DNA methyltransferase 1 (DNMT1), the ATP-dependent and actin-dependent helicases, and the ten-eleven translocation (TET) dioxygenases, suggest that these enzymes are involved in an epigenetic cycle that maintains the unmethylated state at these sites by resolving non-B structure, preventing both the sequestration of DNA methyltransferases (DNMTs) and hypermethylation in normal cells. Presentation of the hypothesis The innate tendency of DNA sequences present at fragile sites to form non-B DNA structures results in de novo methylation of DNA at these sites that is held in check in normal cells by the action of ATP-dependent and actin-dependent helicases coupled with the action of TET dioxygenases. This constitutes a previously unrecognized epigenetic repair cycle in which spontaneously forming non-B DNA structures formed at fragile sites are methylated by DNMTs as they are removed by the action of ATP-dependent and actin-dependent helicases, with the resulting nascent methylation rendered non-transmissible by TET dioxygenases. Testing the hypothesis A strong prediction of the hypothesis is that knockdown of ATP-dependent and actin-dependent helicases will result in enhanced bisulfite sensitivity and hypermethylation at non-B structures in multiple fragile sites coupled with global hypomethylation. Implications of the hypothesis A key implication of the hypothesis is that helicases, like the lymphoid-specific helicase and alpha thalassemia/mental retardation syndrome X-linked helicase, passively promote accurate maintenance of DNA methylation by preventing the sequestration of DNMTs at sites of unrepaired non-B DNA

  13. CONFORMANCE IMPROVEMENT USING GELS

    SciTech Connect

    Randall S. Seright

    2004-09-30

    This report describes work performed during the third and final year of the project, ''Conformance Improvement Using Gels.'' Corefloods revealed throughput dependencies of permeability reduction by polymers and gels that were much more prolonged during oil flow than water flow. This behavior was explained using simple mobility ratio arguments. A model was developed that quantitatively fits the results and predicts ''clean up'' times for oil productivity when production wells are returned to service after application of a polymer or gel treatment. X-ray computed microtomography studies of gels in strongly water-wet Berea sandstone and strongly oil-wet porous polyethylene suggested that oil penetration through gel-filled pores occurs by a gel-dehydration mechanism, rather than gel-ripping or gel-displacement mechanisms. In contrast, analysis of data from the University of Kansas suggests that the gel-ripping or displacement mechanisms are more important in more permeable, strongly water-wet sandpacks. These findings help to explain why aqueous gels can reduce permeability to water more than to oil under different conditions. Since cement is the most commonly used material for water shutoff, we considered when gels are preferred over cements. Our analysis and experimental results indicated that cement cannot be expected to completely fill (top to bottom) a vertical fracture of any width, except near the wellbore. For vertical fractures with apertures less than 4 mm, the cement slurry will simply not penetrate very far into the fracture. For vertical fractures with apertures greater than 4 mm, the slurry may penetrate a substantial distance into the bottom part of the fracture. However, except near the wellbore, the upper part of the fracture will remain open due to gravity segregation. We compared various approaches to plugging fractures using gels, including (1) varying polymer content, (2) varying placement (extrusion) rate, (3) using partially formed gels, (4

  14. CONFORMANCE IMPROVEMENT USING GELS

    SciTech Connect

    Randall S. Seright

    2004-03-01

    This technical progress report describes work performed from September 1, 2003, through February 29, 2004, for the project, ''Conformance Improvement Using Gels.'' We examined the properties of several ''partially formed'' gels that were formulated with a combination of high and low molecular weight HPAM polymers. After placement in 4-mm-wide fractures, these gels required about 25 psi/ft for brine to breach the gel (the best performance to date in fractures this wide). After this breach, stabilized residual resistance factors decreased significantly with increased flow rate. Also, residual resistance factors were up to 9 times greater for water than for oil. Nevertheless, permeability reduction factors were substantial for both water and oil flow. Gel with 2.5% chopped fiberglass effectively plugged 4-mm-wide fractures if a 0.5-mm-wide constriction was present. The ability to screen-out at a constriction appears crucial for particulate incorporation to be useful in plugging fractures. In addition to fiberglass, we examined incorporation of polypropylene fibers into gels. Once dispersed in brine or gelant, the polypropylene fibers exhibited the least gravity segregation of any particulate that we have tested to date. In fractures with widths of at least 2 mm, 24-hr-old gels (0.5% high molecular weight HPAM) with 0.5% fiber did not exhibit progressive plugging during placement and showed extrusion pressure gradients similar to those of gels without the fiber. The presence of the fiber roughly doubled the gel's resistance to first breach by brine flow. The breaching pressure gradients were not as large as for gels made with high and low molecular weight polymers (mentioned above). However, their material requirements and costs (i.e., polymer and/or particulate concentrations) were substantially lower than for those gels. A partially formed gel made with 0.5% HPAM did not enter a 0.052-mm-wide fracture when applying a pressure gradient of 65 psi/ft. This result

  15. Modeling chemoresponsive polymer gels.

    PubMed

    Kuksenok, Olga; Deb, Debabrata; Dayal, Pratyush; Balazs, Anna C

    2014-01-01

    Stimuli-responsive gels are vital components in the next generation of smart devices, which can sense and dynamically respond to changes in the local environment and thereby exhibit more autonomous functionality. We describe recently developed computational methods for simulating the properties of such stimuli-responsive gels in the presence of optical, chemical, and thermal gradients. Using these models, we determine how to harness light to drive shape changes and directed motion in spirobenzopyran-containing gels. Focusing on oscillating gels undergoing the Belousov-Zhabotinksy reaction, we demonstrate that these materials can spontaneously form self-rotating assemblies, or pinwheels. Finally, we model temperature-sensitive gels that encompass chemically reactive filaments to optimize the performance of this system as a homeostatic device for regulating temperature. These studies could facilitate the development of soft robots that autonomously interconvert chemical and mechanical energy and thus perform vital functions without the continuous need of external power sources. PMID:24498954

  16. Ultraflexible organic amplifier with biocompatible gel electrodes.

    PubMed

    Sekitani, Tsuyoshi; Yokota, Tomoyuki; Kuribara, Kazunori; Kaltenbrunner, Martin; Fukushima, Takanori; Inoue, Yusuke; Sekino, Masaki; Isoyama, Takashi; Abe, Yusuke; Onodera, Hiroshi; Someya, Takao

    2016-01-01

    In vivo electronic monitoring systems are promising technology to obtain biosignals with high spatiotemporal resolution and sensitivity. Here we demonstrate the fabrication of a biocompatible highly conductive gel composite comprising multi-walled carbon nanotube-dispersed sheet with an aqueous hydrogel. This gel composite exhibits admittance of 100 mS cm(-2) and maintains high admittance even in a low-frequency range. On implantation into a living hypodermal tissue for 4 weeks, it showed a small foreign-body reaction compared with widely used metal electrodes. Capitalizing on the multi-functional gel composite, we fabricated an ultrathin and mechanically flexible organic active matrix amplifier on a 1.2-μm-thick polyethylene-naphthalate film to amplify (amplification factor: ∼200) weak biosignals. The composite was integrated to the amplifier to realize a direct lead epicardial electrocardiography that is easily spread over an uneven heart tissue. PMID:27125910

  17. Ultraflexible organic amplifier with biocompatible gel electrodes

    NASA Astrophysics Data System (ADS)

    Sekitani, Tsuyoshi; Yokota, Tomoyuki; Kuribara, Kazunori; Kaltenbrunner, Martin; Fukushima, Takanori; Inoue, Yusuke; Sekino, Masaki; Isoyama, Takashi; Abe, Yusuke; Onodera, Hiroshi; Someya, Takao

    2016-04-01

    In vivo electronic monitoring systems are promising technology to obtain biosignals with high spatiotemporal resolution and sensitivity. Here we demonstrate the fabrication of a biocompatible highly conductive gel composite comprising multi-walled carbon nanotube-dispersed sheet with an aqueous hydrogel. This gel composite exhibits admittance of 100 mS cm-2 and maintains high admittance even in a low-frequency range. On implantation into a living hypodermal tissue for 4 weeks, it showed a small foreign-body reaction compared with widely used metal electrodes. Capitalizing on the multi-functional gel composite, we fabricated an ultrathin and mechanically flexible organic active matrix amplifier on a 1.2-μm-thick polyethylene-naphthalate film to amplify (amplification factor: ~200) weak biosignals. The composite was integrated to the amplifier to realize a direct lead epicardial electrocardiography that is easily spread over an uneven heart tissue.

  18. Coupling the Alkaline-Surfactant-Polymer Technology and The Gelation Technology to Maximize Oil Production

    SciTech Connect

    Malcolm Pitts; Jie Qi; Dan Wilson; David Stewart; Bill Jones

    2005-10-01

    Gelation technologies have been developed to provide more efficient vertical sweep efficiencies for flooding naturally fractured oil reservoirs or more efficient areal sweep efficiency for those with high permeability contrast ''thief zones''. The field proven alkaline-surfactant-polymer technology economically recovers 15% to 25% OOIP more oil than waterflooding from swept pore space of an oil reservoir. However, alkaline-surfactant-polymer technology is not amenable to naturally fractured reservoirs or those with thief zones because much of injected solution bypasses target pore space containing oil. This work investigates whether combining these two technologies could broaden applicability of alkaline-surfactant-polymer flooding into these reservoirs. A prior fluid-fluid report discussed interaction of different gel chemical compositions and alkaline-surfactant-polymer solutions. Gel solutions under dynamic conditions of linear corefloods showed similar stability to alkaline-surfactant-polymer solutions as in the fluid-fluid analyses. Aluminum-polyacrylamide, flowing gels are not stable to alkaline-surfactant-polymer solutions of either pH 10.5 or 12.9. Chromium acetate-polyacrylamide flowing and rigid flowing gels are stable to subsequent alkaline-surfactant-polymer solution injection. Rigid flowing chromium acetate-polyacrylamide gels maintained permeability reduction better than flowing chromium acetate-polyacrylamide gels. Silicate-polyacrylamide gels are not stable with subsequent injection of either a pH 10.5 or a 12.9 alkaline-surfactant-polymer solution. Chromium acetate-xanthan gum rigid gels are not stable to subsequent alkaline-surfactant-polymer solution injection. Resorcinol-formaldehyde gels were stable to subsequent alkaline-surfactant-polymer solution injection. When evaluated in a dual core configuration, injected fluid flows into the core with the greatest effective permeability to the injected fluid. The same gel stability trends to subsequent

  19. Viscoelasticity of silica gels

    SciTech Connect

    Scherer, G.W.

    1995-12-01

    The response of silica gels to mechanical loads depends on the properties of the solid phase and the permeability of the network. Understanding this behavior is essential for modeling of stresses developed during drying or heating of gels. The permeability and the mechanical properties are readily determined from a simple beam-bending experiment, by measuring the load relaxation that occurs at constant deflection. Load decay results from movement of the liquid within the network; in addition, there may be viscoelastic relaxation of the network itself. Silica gel is viscoelastic in chemically aggressive media, but in inert liquids (such as ethanol or acetone) it is elastic. Experiments show that the viscoelastic relaxation time decreases as the concentration and pH of the water in the pore liquid increase. During drying, the permeability decreases and the viscosity increases, both exhibiting a power-law dependence on density of the gel network.

  20. Testosterone Nasal Gel

    MedlinePlus

    ... enough natural testosterone). Testosterone nasal gel is used only for men with low testosterone levels caused by ... is a controlled substance. Prescriptions may be refilled only a limited number of times; ask your pharmacist ...

  1. Microfluidics with Gel Emulsions

    NASA Astrophysics Data System (ADS)

    Priest, Craig; Surenjav, Enkhtuul; Herminghaus, Stephan; Seemann, Ralf

    2006-03-01

    Microfluidic processing is usually achieved using single phase liquids. Instead, we use monodisperse emulsions to compartment liquids within microchannel geometries. At low continuous phase volume fractions, droplets self-organize to form well-defined arrangements, analogous to foam. While it is well-known that confined geometries can induce rearrangement of foam compartments at the millimeter-scale, similar dynamics are also expected for gel emulsions. We have studied online generation, organization and manipulation of gel emulsions using a variety of microchannel geometries. ``Passive'' reorganization, based on fixed channel geometries, can be supplemented by ``active'' manipulation by incorporating a ferrofluid phase. A ferromagnetic phase facilitates reorganization of liquid compartments on demand using an electromagnetic trigger. Moreover, coalescence between adjacent compartments within a gel emulsion can be induced using electrical potential. Microfluidics using gel emulsions will be well-suited for combinatorial chemistry, DNA sequencing, drug screening and protein crystallizations.

  2. Microfluidics of soft granular gels

    NASA Astrophysics Data System (ADS)

    Nixon, Ryan; Bhattacharjee, Tapomoy; Sawyer, W. Gregory; Angelini, Thomas E.

    Microfluidic methods for encapsulating cells and particles typically involve drop making with two immiscible fluids. The main materials constraint in this approach is surface tension, creating inherent instability between the two fluids. We can eliminate this instability by using miscible inner and outer phases. This is achieved by using granular micro gels which are chemically miscible but physically do not mix. These microgels are yield stress materials, so they flow as solid plugs far from shear gradients, and fluidize where gradients are generated - near an injection nozzle for example. We have found that tuning the yield stress of the material by varying polymer concentration, device performance can be controlled. The solid like behavior of the gel allows us to produces infinitely stable jets that maintain their integrity and configuration over long distances and times. These properties can be combined and manipulated to produce discrete particulate bunches of an inner phase, flowing inside of an outer phase, well enough even to print a Morse code message suspended within flow chambers about a millimeter in diameter moving at millimeters a second.

  3. Preparation of chitosan gel

    NASA Astrophysics Data System (ADS)

    Moussaoui, Y.; Mnasri, N.; Elaloui, E.; Ben Salem, R.; Lagerge, S.; de Menorval, L. C.

    2012-06-01

    Aerogel conditioning of the chitosan makes it possible to prepare porous solids of significant specific surface. The increase in the chitosan concentration or the degree of acetylation decreases the specific surface of the synthesized chitosan gel. Whereas drying with supercritical CO2 more effectively makes it possible to preserve the volume of the spheres of gel and to have a more significant specific surface in comparison with evaporative drying.

  4. Crystallization from Gels

    NASA Astrophysics Data System (ADS)

    Narayana Kalkura, S.; Natarajan, Subramanian

    Among the various crystallization techniques, crystallization in gels has found wide applications in the fields of biomineralization and macromolecular crystallization in addition to crystallizing materials having nonlinear optical, ferroelectric, ferromagnetic, and other properties. Furthermore, by using this method it is possible to grow single crystals with very high perfection that are difficult to grow by other techniques. The gel method of crystallization provides an ideal technique to study crystal deposition diseases, which could lead to better understanding of their etiology. This chapter focuses on crystallization in gels of compounds that are responsible for crystal deposition diseases. The introduction is followed by a description of the various gels used, the mechanism of gelling, and the fascinating phenomenon of Liesegang ring formation, along with various gel growth techniques. The importance and scope of study on crystal deposition diseases and the need for crystal growth experiments using gel media are stressed. The various crystal deposition diseases, viz. (1) urolithiasis, (2) gout or arthritis, (3) cholelithiasis and atherosclerosis, and (4) pancreatitis and details regarding the constituents of the crystal deposits responsible for the pathological mineralization are discussed. Brief accounts of the theories of the formation of urinary stones and gallstones and the role of trace elements in urinary stone formation are also given. The crystallization in gels of (1) the urinary stone constituents, viz. calcium oxalate, calcium phosphates, uric acid, cystine, etc., (2) the constituents of the gallstones, viz. cholesterol, calcium carbonate, etc., (3) the major constituent of the pancreatic calculi, viz., calcium carbonate, and (4) cholic acid, a steroidal hormone are presented. The effect of various organic and inorganic ions, trace elements, and extracts from cereals, herbs, and fruits on the crystallization of major urinary stone and gallstone

  5. Polyacrylamide gel electrophoresis.

    PubMed

    Chrambach, A; Rodbard, D

    1971-04-30

    Polyacrylamide gel electrophoresis (PAGE) provides a versatile, gentle, high resolution method for fractionation and physical-chemical characterization of molecules on the basis of size, conformation, and net charge. The polymerization reaction can be rigorously controlled to provide uniform gels of reproducible, measurable pore size over a wide range. This makes it possible to obtain reproducible relative mobility (Rf) values as physical-chemical constants. Application and extension of Ogston's (random fiber) model for a gel allows for calculation of molecular volume, surface area, or radius, free mobility, and valence from RJ measurements at several gel concentrations, to calculate gel concentration for optimal resolution, and to predict behavior of macromolecules on gel gradients by computerized methods. Extension of classical moving boundary theory has been used to generate multiphasic buffer systems (providing selective stacking, unstacking, restacking, and preparative steady-state-stacking) with known operating characteristics for any pH at 0 degrees and 25 degrees C. A general strategy for isolation of macromolecules and for macromolecular mapping has been developed. Preparative scale PAGE is operational for milligram loads and feasible for gram quantities. PMID:4927678

  6. CONFORMANCE IMPROVEMENT USING GELS

    SciTech Connect

    Randall S. Seright

    2002-02-28

    This technical progress report describes work performed from June 20 through December 19, 2001, for the project, ''Conformance Improvement Using Gels''. Interest has increased in some new polymeric products that purport to substantially reduce permeability to water while causing minimum permeability reduction to oil. In view of this interest, we are currently studying BJ's Aqua Con. Results from six corefloods revealed that the Aqua Con gelant consistently reduced permeability to water more than that to oil. However, the magnitude of the disproportionate permeability reduction varied significantly for the various experiments. Thus, as with most materials tested to date, the issue of reproducibility and control of the disproportionate permeability remains to be resolved. Concern exists about the ability of gels to resist washout after placement in fractures. We examined whether a width constriction in the middle of a fracture would cause different gel washout behavior upstream versus downstream of the constriction. Tests were performed using a formed Cr(III)-acetate-HPAM gel in a 48-in.-long fracture with three sections of equal length, but with widths of 0.08-, 0.02-, and 0.08-in., respectively. The pressure gradients during gel extrusion (i.e., placement) were similar in the two 0.08-in.-wide fracture sections, even though they were separated by a 0.02-in.-wide fracture section. The constriction associated with the middle fracture section may have inhibited gel washout during the first pulse of brine injection after gel placement. However, during subsequent phases of brine injection, the constriction did not inhibit washout in the upstream fracture section any more than in the downstream section.

  7. Simple Fixed Functional Space Maintainer

    PubMed Central

    Sarawgi, Aditi; Marwah, Nikhil; Gumber, Parvind; Dutta, Samir

    2014-01-01

    ABSTRACT% Premature loss of a primary tooth is one of the most common etiology for malocclusion. Space maintainers are employed to prevent this complication. In anterior region, esthetics is an important concern along with function and space management. Fiber-reinforced composite (FRC) retained space maintainer solves all these purposes ef ficiently and ef fectively. In addition, the technique is simple and the appliance is very comfortable inside the oral cavity. Here is a case of premature loss of anterior primary tooth which was replaced by FRC retained esthetic functional space maintainer. The appliance was found to be functioning satisfactorily inside the oral cavity till the last visit (1 Year). How to cite this article: Goenka P, Sarawgi A, Marwah N, Gumber P, Dutta S. Simple Fixed Functional Space Maintainer. Int J Clin Pediatr Dent 2014;7(3):225-228. PMID:25709309

  8. Growth of lead tin telluride crystals in gels

    NASA Technical Reports Server (NTRS)

    Barber, Patrick G.

    1986-01-01

    Improved gels and several geometries were investigated for use in growing crystals. The use of lead sulfide test crystals proved workable, but it was impossible to obtain and maintain a sufficiently concentrated telluride ion solution to successfully grow lead telluride crystals. It appears that oxygen in the solution is capable of oxidizing the telluride ion up to tellurium metal. The method may still be successful, but only if precautions are taken to eliminate dissolved oxygen from the gels and aqueous solutions and to maintain a suitable concentration of telluride, Te(2)-(aq.).

  9. Swelling of Olympic Gels

    NASA Astrophysics Data System (ADS)

    Lang, M.; Fischer, J.; Werner, M.; Sommer, J.-U.

    2014-06-01

    The swelling equilibrium of Olympic gels, which are composed of entangled cyclic polymers, is studied by Monte Carlo simulations. In contrast to chemically cross-linked polymer networks, we observe that Olympic gels made of chains with a larger degree of polymerization, N, exhibit a smaller equilibrium swelling degree, Q∝N-0.28ϕ0-0.72, at the same polymer volume fraction ϕ0 at network preparation. This observation is explained by a desinterspersion (reorganization with release of nontrapped entanglements) process of overlapping nonconcatenated rings upon swelling.

  10. Cell viability in a wet silica gel.

    PubMed

    Nieto, Alejandra; Areva, Sami; Wilson, Timothy; Viitala, Reeta; Vallet-Regi, Maria

    2009-11-01

    A modified two-step sol-gel route using silicon ethoxide (TEOS) has been used to synthesize amorphous sol-gel-derived silica, which has been successfully used as a cell encapsulation matrix for 3T3 mouse fibroblasts and CRL-2595 epithelial cells due to its non-toxicity. The sol-gel procedure comprised a first, low pH hydrolysis step, followed by a neutral condensation-gelation step. A high water-to-TEOS ratio and the addition of d-glucose as a porogen and source of nutrients were chosen to minimize silica dissolution and improve the biocompatibility of the process. Indeed, the cell integrity in the encapsulation process was preserved by alcohol removal from the starting solution. Cells were then added in a buffered medium, causing rapid gelation and entrapment of the cells within a randomly structured siloxane matrix in the shape of a monolith, which was maintained in the wet state. MTT and alamarBlue assays were used to check the cytotoxicity of the silica gels and the viability of entrapped cells at initial times in contact with silica. To improve cell attachment, cell clumping experiments - where groups of cells were formed - were designed, rendering improved viability. The obtained materials are therefore excellent candidates for designing tissue-culture scaffolds and implantable bioreactors for biomedical applications. PMID:19481618

  11. Self-selecting fluid intake while maintaining high carbohydrate availability does not impair half-marathon performance.

    PubMed

    Lee, M J C; Hammond, K M; Vasdev, A; Poole, K L; Impey, S G; Close, G L; Morton, J P

    2014-12-01

    We aimed to test the hypothesis that self-selecting fluid intake but maintaining high exogenous CHO availability (60 g/h) does not compromise half-marathon performance. 15 participants completed 3 half-marathons while drinking a 6% CHO solution to guidelines (DRINK) or a non-caloric solution in self-selected volumes when consuming 3×glucose (20 g) gels (G-GEL) or glucose-fructose (13 g glucose+7 g fructose) gels (GF-GEL) per hour. Fluid intake (DRINK: 1 557±182, G-GEL: 473±234, GF-GEL: 404±144 ml) and percent body mass loss (DRINK: - 0.8±0.9, G-GEL: - 2.0±0.6, GF-GEL: -2.3±1.1) were different (P<0.05) between conditions, though race time did not differ (DRINK: 110.6±14.4, G-GEL: 110.3±14.6, GF-GEL: 113.7±12.8 min). In G-GEL, there was a positive correlation (P<0.05) between body mass loss and race time. Plasma glucose was lower (P<0.05) in GF-GEL compared with other conditions, and total CHO oxidation (DRINK: 3.2±0.5, G-GEL: 3.0±0.4, GF-GEL: 2.6±0.4 g/min) was lower (P=0.06) in this trial. Self-selecting fluid intake but maintaining high CHO availability does not impair half-marathon performance. Additionally, consuming glucose-fructose mixtures in sub-optimal amounts reduces plasma glucose and total rates of CHO oxidation. PMID:25144431

  12. Maintaining qualification for 340B.

    PubMed

    Gricius, Robert F; Wong, Douglas

    2016-03-01

    After initial acceptance in the 340B Drug Pricing Program, hospitals and health systems should monitor and take steps to maintain their disproportionate share hospital status to continue to qualify for participation. Proactively managing the Supplemental Security Income (SSI) Ratio will ensure the organization avoids an unexpected decline in the Medicare portion of its 340B patient base. Even with the surge resulting from Medicaid expansion, tracking patient eligibility for Medicare/ SSI to ensure all patients who qualify are appropriately enrolled in the program is an important step in maintaining 340B program eligibility. PMID:27183761

  13. Strategies for Maintaining Community Integration.

    ERIC Educational Resources Information Center

    Gruber, Fred

    1986-01-01

    This article outlines strategies of maintaining integration emphasizing: (1) housing offices and counseling; (2) community action to alter real estate policies; (3) school action including public relations and human relations thinking; (4) community organization of commercial and religious institutions; (5) financial incentives for pro-integrative…

  14. Maintaining Sustainability for Green Schools

    ERIC Educational Resources Information Center

    Kennedy, Mike

    2011-01-01

    The promise of sustainably designed school facilities is that they will operate more efficiently and last longer than buildings constructed in more traditional ways. But that promise comes with a big if. The payoff is delivered only if the facility managers operate and maintain the buildings in ways that adhere to sustainable strategies called for…

  15. Synthesis, structure, and mechanical properties of silica nanocomposite polyrotaxane gels

    PubMed Central

    Matsui, Daisuke; Mayumi, Koichi

    2015-01-01

    Summary A significantly soft and tough nanocomposite gel was realized by a novel network formed using cyclodextrin-based polyrotaxanes. Covalent bond formation between the cyclic components of polyrotaxanes and the surface of silica nanoparticles (15 nm diameter) resulted in an infinite network structure without direct bonds between the main chain polymer and the silica. Small-angle X-ray scattering revealed that the homogeneous distribution of silica nanoparticles in solution was maintained in the gel state. Such homogeneous nanocomposite gels were obtained with at least 30 wt % silica content, and the Young’s modulus increased with silica content. Gelation did not occur without silica. This suggests that the silica nanoparticles behave as cross-linkers. Viscoelastic measurements of the nanocomposite gels showed no stress relaxation regardless of the silica content for <20% compression strain, indicating an infinite stable network without physical cross-links that have finite lifetime. On the other hand, the infinite network exhibited an abnormally low Young’s modulus, ~1 kPa, which is not explainable by traditional rubber theory. In addition, the composite gels were tough enough to completely maintain the network structure under 80% compression strain. These toughness and softness properties are attributable to both the characteristic sliding of polymer chains through the immobilized cyclodextrins on the silica nanoparticle and the entropic contribution of the cyclic components to the elasticity of the gels. PMID:26664642

  16. Synthesis, structure, and mechanical properties of silica nanocomposite polyrotaxane gels.

    PubMed

    Kato, Kazuaki; Matsui, Daisuke; Mayumi, Koichi; Ito, Kohzo

    2015-01-01

    A significantly soft and tough nanocomposite gel was realized by a novel network formed using cyclodextrin-based polyrotaxanes. Covalent bond formation between the cyclic components of polyrotaxanes and the surface of silica nanoparticles (15 nm diameter) resulted in an infinite network structure without direct bonds between the main chain polymer and the silica. Small-angle X-ray scattering revealed that the homogeneous distribution of silica nanoparticles in solution was maintained in the gel state. Such homogeneous nanocomposite gels were obtained with at least 30 wt % silica content, and the Young's modulus increased with silica content. Gelation did not occur without silica. This suggests that the silica nanoparticles behave as cross-linkers. Viscoelastic measurements of the nanocomposite gels showed no stress relaxation regardless of the silica content for <20% compression strain, indicating an infinite stable network without physical cross-links that have finite lifetime. On the other hand, the infinite network exhibited an abnormally low Young's modulus, ~1 kPa, which is not explainable by traditional rubber theory. In addition, the composite gels were tough enough to completely maintain the network structure under 80% compression strain. These toughness and softness properties are attributable to both the characteristic sliding of polymer chains through the immobilized cyclodextrins on the silica nanoparticle and the entropic contribution of the cyclic components to the elasticity of the gels. PMID:26664642

  17. The SWISS-2DPAGE database of two-dimensional polyacrylamide gel electrophoresis.

    PubMed Central

    Appel, R D; Sanchez, J C; Bairoch, A; Golaz, O; Ravier, F; Pasquali, C; Hughes, G J; Hochstrasser, D F

    1994-01-01

    SWISS-2DPAGE is a database of proteins identified on two-dimensional polyacrylamide gel electrophoresis (2-D PAGE), created and maintained at the University Hospital of Geneva in collaboration with the Department of Medical Biochemistry of Geneva University. The proteins have been identified on various 2-D PAGE reference maps by microsequencing, immunoblotting, gel comparison and amino acid composition. Images PMID:7937063

  18. Disturbance maintains alternative biome states.

    PubMed

    Dantas, Vinícius de L; Hirota, Marina; Oliveira, Rafael S; Pausas, Juli G

    2016-01-01

    Understanding the mechanisms controlling the distribution of biomes remains a challenge. Although tropical biome distribution has traditionally been explained by climate and soil, contrasting vegetation types often occur as mosaics with sharp boundaries under very similar environmental conditions. While evidence suggests that these biomes are alternative states, empirical broad-scale support to this hypothesis is still lacking. Using community-level field data and a novel resource-niche overlap approach, we show that, for a wide range of environmental conditions, fire feedbacks maintain savannas and forests as alternative biome states in both the Neotropics and the Afrotropics. In addition, wooded grasslands and savannas occurred as alternative grassy states in the Afrotropics, depending on the relative importance of fire and herbivory feedbacks. These results are consistent with landscape scale evidence and suggest that disturbance is a general factor driving and maintaining alternative biome states and vegetation mosaics in the tropics. PMID:26493189

  19. On research: new contraceptive gel prevents pregnancy and STDs.

    PubMed

    Venere, E

    1996-09-30

    A contraceptive gel, which prevents pregnancy as well as sexually transmitted diseases, created by scientists at the Johns Hopkins University has been selected for clinical trials by the National Institutes of Health. The gel is a vaginal microbicide that kills both sperm and microbes. It also destroys white blood cells in sperm and cervical mucus that can be infected with HIV. The creators of the gel found out that an effective acidic microbicide should neither harm the cells of the vaginal lining nor kill the beneficial bacteria in the vagina. Thus they created an ¿acidic buffer¿ that would be unable to penetrate the membranes of beneficial cells, rendering the buffer harmless to those cells. Yet, it would maintain the mild acidity which kills sperm and microbes that are sensitive to acid. The scientists are also developing ways to increase the gel's effectiveness by incorporating antibodies and vaccines. Additional research could result in a contraceptive gel lasting for 24 hours or longer. The gel, which they call BufferGel, may be marketed after undergoing extensive tests over the next 2 years. PMID:12295770

  20. NMG documentation, part 3: maintainer`s guide

    SciTech Connect

    Fritsch, F.N.; Dickinson, R.P. Jr.

    1996-07-01

    This is the third of a three-part report documenting NMG, the Numerical Mathematics Guide. Part I is aimed at the user of the systenL It contains an introduction, with an out- line of the complete report, and Chapter 1, User`s Point of View. Part II is aimed at the programmer and contains Chapter 2, How It Works. Part III is aimed at the maintainer of NMG and contains Chapter 3, Maintenance, and Chapter 4, Validation. Because its contents are so specialized, Part III will receive only limited distribution. Note that each chapter has its own page numbering and table of contents.

  1. Staradmin -- Starlink User Database Maintainer

    NASA Astrophysics Data System (ADS)

    Fish, Adrian

    The subject of this SSN is a utility called STARADMIN. This utility allows the system administrator to build and maintain a Starlink User Database (UDB). The principal source of information for each user is a text file, named after their username. The content of each file is a list consisting of one keyword followed by the relevant user data per line. These user database files reside in a single directory. The STARADMIN program is used to manipulate these user data files and automatically generate user summary lists.

  2. Clarification Procedure for Gels

    NASA Technical Reports Server (NTRS)

    Barber, Patrick G.; Simpson, Norman R.

    1987-01-01

    Procedure developed to obtain transparent gels with consistencies suitable for crystal growth, by replacing sodium ions in silicate solution with potassium ions. Clarification process uses cation-exchange resin to replace sodium ions in stock solution with potassium ions, placed in 1M solution of soluble potassium salt. Slurry stirred for several hours to allow potassium ions to replace all other cations on resin. Supernatant solution decanted through filter, and beads rinsed with distilled water. Rinsing removes excess salt but leaves cation-exchange beads fully charged with potassium ions.

  3. High transparent shape memory gel

    NASA Astrophysics Data System (ADS)

    Gong, Jin; Arai, Masanori; Kabir, M. H.; Makino, Masato; Furukawa, Hidemitsu

    2014-03-01

    Gels are a new material having three-dimensional network structures of macromolecules. They possess excellent properties as swellability, high permeability and biocompatibility, and have been applied in various fields of daily life, food, medicine, architecture, and chemistry. In this study, we tried to prepare new multi-functional and high-strength gels by using Meso-Decoration (Meso-Deco), one new method of structure design at intermediate mesoscale. High-performance rigid-rod aromatic polymorphic crystals, and the functional groups of thermoreversible Diels-Alder reaction were introduced into soft gels as crosslinkable pendent chains. The functionalization and strengthening of gels can be realized by meso-decorating the gels' structure using high-performance polymorphic crystals and thermoreversible pendent chains. New gels with good mechanical properties, novel optical properties and thermal properties are expected to be developed.

  4. Foam and gel decontamination techniques

    SciTech Connect

    McGlynn, J.F.; Rankin, W.N.

    1989-01-01

    The Savannah River Site is investigating decontamination technology to improve current decontamination techniques, and thereby reduce radiation exposure to plant personnel, reduce uptake of radioactive material, and improve safety during decontamination and decommissioning activities. When decontamination chemicals are applied as foam and gels, the contact time and cleaning ability of the chemical increases. Foam and gel applicators apply foam or gel that adheres to the surface being decontaminated for periods ranging from fifteen minutes (foam) to infinite contact (gel). This equipment was started up in a cold environment. The desired foam and gel consistency was achieved, operators were trained in its proper maintenance and operation, and the foam and gel were applied to walls, ceilings, and hard to reach surfaces. 17 figs.

  5. Polyoxometalate-based Supramolecular Gel

    NASA Astrophysics Data System (ADS)

    He, Peilei; Xu, Biao; Liu, Huiling; He, Su; Saleem, Faisal; Wang, Xun

    2013-05-01

    Self-assemblyings of surfactant-encapsulated Wells-Dawson polyoxometalates (SEPs) nanobuilding blocks in butanone and esters yielded supramolecular gels showing thermo and photo responsive properties. The gels can be further polymerized if unsaturated esters were used and subsequently electrospinned into nanowires and non-woven mats. The as-prepared non-woven mats have a Young's modulus as high as 542.55 MPa. It is believed that this supramolecular gel is a good platform for polyoxometalates processing.

  6. Maintaining consistency in distributed systems

    NASA Technical Reports Server (NTRS)

    Birman, Kenneth P.

    1991-01-01

    In systems designed as assemblies of independently developed components, concurrent access to data or data structures normally arises within individual programs, and is controlled using mutual exclusion constructs, such as semaphores and monitors. Where data is persistent and/or sets of operation are related to one another, transactions or linearizability may be more appropriate. Systems that incorporate cooperative styles of distributed execution often replicate or distribute data within groups of components. In these cases, group oriented consistency properties must be maintained, and tools based on the virtual synchrony execution model greatly simplify the task confronting an application developer. All three styles of distributed computing are likely to be seen in future systems - often, within the same application. This leads us to propose an integrated approach that permits applications that use virtual synchrony with concurrent objects that respect a linearizability constraint, and vice versa. Transactional subsystems are treated as a special case of linearizability.

  7. COOPERATION MAINTAINED BY FITNESS ADJUSTMENT

    PubMed Central

    TAYLOR, CHRISTINE; CHEN, JANET; IWASA, YOH

    2008-01-01

    Questions Whether or not cooperation can be enhanced if players with a performance higher than the mean are forced to pay an additional cost in each generation? Mathematical Methods Analysis of replicator dynamics with mutation. The ESS distribution of cooperation level is obtained. Key Assumptions Players engage in cooperative dilemma game, and at the end of each generation, those with higher performance than the mean are forced to pay additional cost. Conclusions Without mutation, the entire population eventually conforms to a single cooperation level determined by the initial composition of the population. With mutation, there is an equilibrium distribution of cooperation level, which has a peak at an intermediate level of cooperation. Whether it is institutionalized such as tax or just a social custom, fitness adjustment based ultimately on people’s emtion of “envy” is able to maintain cooperation. PMID:19079742

  8. Installing and maintaining gear pumps

    SciTech Connect

    Whitmire, K.

    1996-03-01

    While not as common as centrifugal pumps in the CPI, gear pumps play important roles in handling many of today`s more difficult-to-pump fluids. Because they operate at lower speeds -- generally, 900 rpm or less -- their seals and bearings tend to last longer than those of centrifugal models. In addition, unlike centrifugal pumps, gear pumps` flows are independent of their systems` pressure curves, and they can handle a wider range of viscosities. Although high-flow, low-head applications remain the domain of centrifugal pumps, the use of gear pumps is increasing in the chemical process industries (CPI). While some application boundaries between gears and centrifugals are blurring, there are some crucial differences between the way the two are operated and maintained -- for example, where pressure relief is concerned. This article provides a general summary of gear pump characteristics and applications, highlighting critical aspects of installation, operation and maintenance.

  9. When to maintain centrifugal pumps

    SciTech Connect

    Karassik, I.J.

    1993-04-01

    Centrifugal pumps comprise critical maintenance equipment. The rationale of when to maintain them relates to a spreading tendency to contain costs in the face of tight money. Plant managers are thus entitled to a thorough analysis of whether reduced expenditures truly lower costs or actually hinder maintenance and increase costs. Absence of such an analysis hides the fact that proper and timely maintenance has a double effect: it not only reduces power consumption but also extends equipment life, and thus reduces the frequency of labor and material expenditures for scheduled or crisis maintenance. Centrifugal pump maintenance can demonstrate well the validity of this observation. The paper discusses: restoring internal clearances; real cost of renewing clearances; and monitoring clearances and pump performance.

  10. Electrically controlled polymeric gel actuators

    DOEpatents

    Adolf, Douglas B.; Shahinpoor, Mohsen; Segalman, Daniel J.; Witkowski, Walter R.

    1993-01-01

    Electrically controlled polymeric gel actuators or synthetic muscles capable of undergoing substantial expansion and contraction when subjected to changing pH environments, temperature, or solvent. The actuators employ compliant containers for the gels and their solvents. The gels employed may be cylindrical electromechanical gel fibers such as polyacrylamide fibers or a mixture of poly vinyl alcohol-polyacrylic acid arranged in a parallel aggregate and contained in an electrolytic solvent bath such as salt water. The invention includes smart, electrically activated devices exploiting this phenomenon. These devices are capable of being manipulated via active computer control as large displacement actuators for use in adaptive structure such as robots.

  11. Electrically controlled polymeric gel actuators

    DOEpatents

    Adolf, D.B.; Shahinpoor, M.; Segalman, D.J.; Witkowski, W.R.

    1993-10-05

    Electrically controlled polymeric gel actuators or synthetic muscles are described capable of undergoing substantial expansion and contraction when subjected to changing pH environments, temperature, or solvent. The actuators employ compliant containers for the gels and their solvents. The gels employed may be cylindrical electromechanical gel fibers such as polyacrylamide fibers or a mixture of poly vinyl alcohol-polyacrylic acid arranged in a parallel aggregate and contained in an electrolytic solvent bath such as salt water. The invention includes smart, electrically activated devices exploiting this phenomenon. These devices are capable of being manipulated via active computer control as large displacement actuators for use in adaptive structure such as robots. 11 figures.

  12. Gel polymer electrolytes for batteries

    DOEpatents

    Balsara, Nitash Pervez; Eitouni, Hany Basam; Gur, Ilan; Singh, Mohit; Hudson, William

    2014-11-18

    Nanostructured gel polymer electrolytes that have both high ionic conductivity and high mechanical strength are disclosed. The electrolytes have at least two domains--one domain contains an ionically-conductive gel polymer and the other domain contains a rigid polymer that provides structure for the electrolyte. The domains are formed by block copolymers. The first block provides a polymer matrix that may or may not be conductive on by itself, but that can soak up a liquid electrolyte, thereby making a gel. An exemplary nanostructured gel polymer electrolyte has an ionic conductivity of at least 1.times.10.sup.-4 S cm.sup.-1 at 25.degree. C.

  13. Colloidal thermoresponsive gel forming hybrids.

    PubMed

    Liu, Ruixue; Tirelli, Nicola; Cellesi, Francesco; Saunders, Brian R

    2010-09-15

    Colloidal hybrids comprise organic and inorganic components and are attracting considerable attention in the literature. Recently, we reported hybrid anisotropic microsheets that formed thermoresponsive gels in polymer solutions [Liu et al., Langmuir, 25, 490, 2009]. Here, we investigate the composition and properties of these hybrid colloids themselves in detail for the first time. Three different cationic PNIPAm (N-isopropylacrylamide) graft copolymers and two inorganic nanoparticle types (laponite and Ludox silica) were used to prepare a range of hybrids. Anisotropic microsheets only formed when laponite particles were added to the copolymer implying directed self-assembly. Aqueous dispersions of the microsheets spontaneously formed gels at room temperature and these gels were thermoresponsive. They represent a new class of gel forming colloid and are termed thermoresponsive gel forming hybrids. The compositions of the hybrids were determined from thermogravimetric analysis and those that gave gel forming behaviour identified. Variable-temperature rheology experiments showed that the elasticity of the gels increased linearly with temperature. The reversibility of the thermally-triggered changes in gel elasticity was investigated. The concentration dependence of the rheology data was well described by elastic percolation scaling theory and the data could be collapsed onto a master curve. The concentration exponent for the elastic modulus was 2.5. The strong attractive interactions that exist between the dispersed gel forming hybrids was demonstrated by the formation of stable thermoresponsive hybrid hydrogels through casting of hybrid dispersions. PMID:20561633

  14. Homogeneity of gels and gel-derived glasses

    NASA Technical Reports Server (NTRS)

    Mukherjee, S. P.

    1984-01-01

    The significance and implications of gel preparation procedures in controlling the homogeneity of multicomponent oxide gels are discussed. The role of physicochemical factors such as the structure and chemical reactivities of alkoxides, the formation of double-metal alkoxides, and the nature of solvent(s) are critically analyzed in the context of homogeneity of gels during gelation. Three procedures for preparing gels in the SiO2-B2O3-Na2O system are examined in the context of cation distribution. Light scattering results for glasses in the SiO2-B2O3-Na2O system prepared by both the gel technique and the conventional technique are examined.

  15. Structurally stable gel bead containing entrapped enzyme and method for manufacture thereof

    DOEpatents

    Woodward, Jonathan

    1998-01-01

    A structurally stable gel bead containing an entrapped enzyme and a method for its manufacture. The enzyme is covalently cross-linked to gelatin in the presence of glutaraldehyde prior to the formation of the gel bead, to prevent leakage of the enzyme. Propylene glycol alginate is then added to the mixture. Once the gel beads are formed, they are then soaked in glutaraldehyde, which imparts structural stability to the gel beads. This method can be used with many types of enzymes, such as proteases, carbohydrases, proteases, ligases, isomerases, oxidoreductases, and specialty enzymes. These and other enzymes can be immobilized in the gel beads and utilized in a number of enzymatic processes. Exogenously added ions are not required to maintain the structural stability of these gel beads.

  16. Structurally stable gel bead containing entrapped enzyme and method for manufacture thereof

    DOEpatents

    Woodward, J.

    1998-12-08

    This research provides a structurally stable gel bead containing an entrapped enzyme and a method for its manufacture. The enzyme is covalently cross-linked to gelatin in the presence of glutaraldehyde prior to the formation of the gel bead, to prevent leakage of the enzyme. Propylene glycol alginate is then added to the mixture. Once the gel beads are formed, they are then soaked in glutaraldehyde, which imparts structural stability to the gel beads. This method can be used with many types of enzymes, such as proteases, carbohydrases, proteases, ligases, isomerases, oxidoreductases, and specialty enzymes. These and other enzymes can be immobilized in the gel beads and utilized in a number of enzymatic processes. Exogenously added ions are not required to maintain the structural stability of these gel beads. 7 figs.

  17. Efficient and selective removal of dyes using imidazolium-based supramolecular gels.

    PubMed

    Cheng, Ni; Hu, Qiongzheng; Guo, Yongxian; Wang, Yong; Yu, Li

    2015-05-20

    A supramolecular gel was constructed by using an imidazolium-based surfactant, N-cetyl-N'-carboxymethyl imidazolium bromide ([N-C16, N'-CO2H-Im]Br), in the DMSO/H2O binary solvent mixtures and investigated as an adsorbent for removing dyes from aqueous solution. The self-assembled gel displays a morphology of microplatelets stacked in bilayer units with interdigitated hydrocarbon tails, and the structure remains unchanged below the sol-gel transition temperature. The gel also exhibits a strong birefringence property and excellent mechanical strength. In particular, the gels show superior performance in removal of anionic dye molecules, for example, removing 80% of eosin Y within 10 min, The constructed gels also present excellent salinity tolerance, even when the concentration of NaCl is 1000 times higher than that of the dye, and can maintain their high efficiency after 25 cycles, indicative of their promise in water treatment. PMID:25938635

  18. Remotely maintained waste transfer pump

    SciTech Connect

    Eargle, J.C.

    1990-12-31

    Westinghouse Savannah River Company (WSRC) operates the Savannah River Site (SRS) for the Department of Energy (DOE). Waste from the processing of irradiated material is stored in large shielded tanks. Treated liquid wastes are to be transferred from these tanks to the Defense Waste Processing Facility (DWPF) for incorporation in glass suitable for storage in a federal repository. Characteristics of the wastes range from water-like liquid to highly viscous wastes containing suspended solids. Pumping head requirements for various conditions ranged from 10 meters (35 feet) to 168 meters (550 feet). A specially designed, cantilever type, remotely operated and maintained pump was designed and built to transfer the wastes. To demonstrate the design, a prototype pump was built and testing thoroughly with simulated waste. Severe vibration problems were overcome by proper drive shaft selection and careful control of the space between the pump shaft and fixed running clearances (sometimes called seals). Eleven pumps are now installed and six pumps have been successfully run in water service.

  19. Remotely maintained waste transfer pump

    SciTech Connect

    Eargle, J.C.

    1990-01-01

    Westinghouse Savannah River Company (WSRC) operates the Savannah River Site (SRS) for the Department of Energy (DOE). Waste from the processing of irradiated material is stored in large shielded tanks. Treated liquid wastes are to be transferred from these tanks to the Defense Waste Processing Facility (DWPF) for incorporation in glass suitable for storage in a federal repository. Characteristics of the wastes range from water-like liquid to highly viscous wastes containing suspended solids. Pumping head requirements for various conditions ranged from 10 meters (35 feet) to 168 meters (550 feet). A specially designed, cantilever type, remotely operated and maintained pump was designed and built to transfer the wastes. To demonstrate the design, a prototype pump was built and testing thoroughly with simulated waste. Severe vibration problems were overcome by proper drive shaft selection and careful control of the space between the pump shaft and fixed running clearances (sometimes called seals). Eleven pumps are now installed and six pumps have been successfully run in water service.

  20. Hydroelectric redevelopment maintains heritage values

    SciTech Connect

    Bulkovshteyn, L.; Chidiac, M.; Hall, W.

    1995-12-31

    The Seymour GS is an 80 year old generating station on the historic Trent-Severn Waterway in Ontario, Canada. The rehabilitation at Seymour was approved by Provincial and Federal authorities on condition that the original appearance of the building be maintained. The capacity of the Generating Station (GS) is being uprated from 3.15 MW to 5.7 MW, by replacing five vertical double runner Francis units with five horizontal Kaplan turbines. The replacement of vertical Francis units with horizontal Kaplan units, necessitated an extensive and innovative demolition approach for the substructure modification. The new turbines required a powerhouse base slab 3.5 m below the grade of the original slab. This required removal of the existing slabs and foundation rock along with most of the interior powerhouse walls. The type of modification and demolition were carefully chosen to accommodate a very tight schedule dictated by the requirement of the Federal Department of Fisheries and Oceans (DFO), where in-water work is restricted to certain months of the year.

  1. 10 CFR 26.71 - Maintaining authorization.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Maintaining authorization. 26.71 Section 26.71 Energy NUCLEAR REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Granting and Maintaining Authorization § 26.71 Maintaining authorization. (a) Individuals may maintain authorization under the following conditions: (1)...

  2. 10 CFR 26.71 - Maintaining authorization.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Maintaining authorization. 26.71 Section 26.71 Energy NUCLEAR REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Granting and Maintaining Authorization § 26.71 Maintaining authorization. (a) Individuals may maintain authorization under the following conditions: (1)...

  3. 10 CFR 26.71 - Maintaining authorization.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Maintaining authorization. 26.71 Section 26.71 Energy NUCLEAR REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Granting and Maintaining Authorization § 26.71 Maintaining authorization. (a) Individuals may maintain authorization under the following conditions: (1)...

  4. 10 CFR 26.71 - Maintaining authorization.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Maintaining authorization. 26.71 Section 26.71 Energy NUCLEAR REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Granting and Maintaining Authorization § 26.71 Maintaining authorization. (a) Individuals may maintain authorization under the following conditions: (1)...

  5. 10 CFR 26.71 - Maintaining authorization.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Maintaining authorization. 26.71 Section 26.71 Energy NUCLEAR REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Granting and Maintaining Authorization § 26.71 Maintaining authorization. (a) Individuals may maintain authorization under the following conditions: (1)...

  6. Antimicrobial Graft Copolymer Gels.

    PubMed

    Harvey, Amanda C; Madsen, Jeppe; Douglas, C W Ian; MacNeil, Sheila; Armes, Steven P

    2016-08-01

    In view of the growing worldwide rise in microbial resistance, there is considerable interest in designing new antimicrobial copolymers. The aim of the current study was to investigate the relationship between antimicrobial activity and copolymer composition/architecture to gain a better understanding of their mechanism of action. Specifically, the antibacterial activity of several copolymers based on 2-(methacryloyloxy)ethyl phosphorylcholine [MPC] and 2-hydroxypropyl methacrylate (HPMA) toward Staphylococcus aureus was examined. Both block and graft copolymers were synthesized using either atom transfer radical polymerization or reversible addition-fragmentation chain transfer polymerization and characterized via (1)H NMR, gel permeation chromatography, rheology, and surface tensiometry. Antimicrobial activity was assessed using a range of well-known assays, including direct contact, live/dead staining, and the release of lactate dehydrogenase (LDH), while transmission electron microscopy was used to study the morphology of the bacteria before and after the addition of various copolymers. As expected, PMPC homopolymer was biocompatible but possessed no discernible antimicrobial activity. PMPC-based graft copolymers comprising PHPMA side chains (i.e. PMPC-g-PHPMA) significantly reduced both bacterial growth and viability. In contrast, a PMPC-PHPMA diblock copolymer comprising a PMPC stabilizer block and a hydrophobic core-forming PHPMA block did not exhibit any antimicrobial activity, although it did form a biocompatible worm gel. Surface tensiometry studies and LDH release assays suggest that the PMPC-g-PHPMA graft copolymer exhibits surfactant-like activity. Thus, the observed antimicrobial activity is likely to be the result of the weakly hydrophobic PHPMA chains penetrating (and hence rupturing) the bacterial membrane. PMID:27409712

  7. Crystallization of steroids in gels

    NASA Astrophysics Data System (ADS)

    Kalkura, S. Narayana; Devanarayanan, S.

    1991-03-01

    The crystal growth and characterization of certain steriods, viz., cholesterol, cholesteryl acetate, β-sitosterol, progesterone and testosterone, in a silica gel medium is discussed. The present study shows that the single test tube diffusion method can be used to grow crystals of steroids in a silica gel medium by the reduction of steroid solubility.

  8. Nanocrystal/sol-gel nanocomposites

    DOEpatents

    Petruska, Melissa A.; Klimov, Victor L.

    2012-06-12

    The present invention is directed to solid composites including colloidal nanocrystals within a sol-gel host or matrix and to processes of forming such solid composites. The present invention is further directed to alcohol soluble colloidal nanocrystals useful in formation of sol-gel based solid composites

  9. Nanocrystal/sol-gel nanocomposites

    DOEpatents

    Petruska, Melissa A.; Klimov, Victor L.

    2007-06-05

    The present invention is directed to solid composites including colloidal nanocrystals within a sol-gel host or matrix and to processes of forming such solid composites. The present invention is further directed to alcohol soluble colloidal nanocrystals useful in formation of sol-gel based solid composites.

  10. Sucrose release from polysaccharide gels.

    PubMed

    Nishinari, Katsuyoshi; Fang, Yapeng

    2016-05-18

    Sucrose release from polysaccharide gels has been studied extensively because it is expected to be useful in understanding flavour release from solid foods and to find a new processing method which produces more palatable and healthier foods. We provide an overview of the release of sucrose and other sugars from gels of agar and related polysaccharides. The addition of sucrose to agar solutions leads to the increase in transparency of the resulting gels and the decrease in syneresis, which is attributed to the decrease in mesh size in gels. The syneresis occurring in the quiescent condition and fluid release induced by compression is discussed. The relationship between the sugar release and the structural, rheological and thermal properties of gels is also discussed. Finally, the future research direction is proposed. PMID:26952168

  11. Bouncing gel balls: Impact of soft gels onto rigid surface

    NASA Astrophysics Data System (ADS)

    Tanaka, Y.; Yamazaki, Y.; Okumura, K.

    2003-07-01

    After being thrown onto a solid substrate, very soft spherical gels bounce repeatedly. Separate rheological measurements suggest that these balls can be treated as nearly elastic. The Hertz contact deformation expected in the static (elastic) limit was observed only at very small impact velocities. For larger velocities, the gel ball deformed into flattened forms like a pancake. We measured the size of the gel balls at the maximal deformation and the contact time as a function of velocities for samples different in the original spherical radius and the Young modulus. The experimental results revealed a number of scaling relations. To interpret these relations, we developed scaling arguments to propose a physical picture.

  12. Maintaining quality in blood banking.

    PubMed

    Harvey, E; Hewison, C; Nevalainen, D E; Lloyd, H L

    1995-03-01

    component will warrant redress. The degree of fault attributed to the producer will in part depend on whether they have met the best available standards at all stages in the preparation of the product. If a Transfusion Service can show that it's operation has external accreditation, particularly to an internationally recognised standard such as ISO 9000 and they can show that staff have been properly trained, that equipment is properly supplied and maintained and that the facility is appropriate to the work being carried out, then the liability that exists when something goes wrong will be reduced.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:7795421

  13. Bacteria immobilised in Gels: Improved methodologies for antifouling and biocontrol applications.

    PubMed

    Holmström, C; Steinberg, P; Christov, V; Christie, G; Kjelleberg, S

    2000-01-01

    A range of bacteria, including the marine bacterium Pseudoalteromonas tunicata which produces antifouling compounds, and Escherichia coli were used to investigate methods for immobilising bacteria in gels. Different types of matrices were screened using the survival of barnacle nauplii as a bioassay. A Dupont® polyvinylalcohol (PVOH) 10% gel was found to be the optimal matrix. This non-toxic gel remained stable in seawater while allowing for an outflux of active biological compounds from the bacterial cells. The presence of active bacterial cells in the matrix was tested by CTC-staining, green fluorescent protein (GFP) expressing bacteria and a barnacle larvae bioassay. The Dupont® PVOH 10% gels containing P. tunicata cells were inhibitory against larvae for a period of up to 2 weeks. In further studies using gels containing immobilised bacteria, the E. coli strain C600 was employed based on its cell size, stress resistance and the fact that a plasmid for the expression of GFP could be transferred and maintained in the cells. Immobilised E. Coli cells maintained their viability in the Dupont® PVOH 10% gels for as long as 2 months, and the life-span of these "biologically active"; gels was increased to more than 2 months by the incorporation of small beads into the gels. The results indicate that bacteria can be immobilised in coatings for periods of time consistent with the needs of some antifouling and antibacterial applications. PMID:22115296

  14. Mechanical Failure in Colloidal Gels

    NASA Astrophysics Data System (ADS)

    Kodger, Thomas Edward

    When colloidal particles in a dispersion are made attractive, they aggregate into fractal clusters which grow to form a space-spanning network, or gel, even at low volume fractions. These gels are crucial to the rheological behavior of many personal care, food products and dispersion-based paints. The mechanical stability of these products relies on the stability of the colloidal gel network which acts as a scaffold to provide these products with desired mechanical properties and to prevent gravitational sedimentation of the dispersed components. Understanding the mechanical stability of such colloidal gels is thus of crucial importance to predict and control the properties of many soft solids. Once a colloidal gel forms, the heterogeneous structure bonded through weak physical interactions, is immediately subject to body forces, such as gravity, surface forces, such as adhesion to a container walls and shear forces; the interplay of these forces acting on the gel determines its stability. Even in the absence of external stresses, colloidal gels undergo internal rearrangements within the network that may cause the network structure to evolve gradually, in processes known as aging or coarsening or fail catastrophically, in a mechanical instability known as syneresis. Studying gel stability in the laboratory requires model colloidal system which may be tuned to eliminate these body or endogenous forces systematically. Using existing chemistry, I developed several systems to study delayed yielding by eliminating gravitational stresses through density matching and cyclic heating to induce attraction; and to study syneresis by eliminating adhesion to the container walls, altering the contact forces between colloids, and again, inducing gelation through heating. These results elucidate the varied yet concomitant mechanisms by which colloidal gels may locally or globally yield, but then reform due to the nature of the physical, or non-covalent, interactions which form

  15. Polyoxometalate-based Supramolecular Gel

    PubMed Central

    He, Peilei; Xu, Biao; Liu, Huiling; He, Su; Saleem, Faisal; Wang, Xun

    2013-01-01

    Self-assemblyings of surfactant-encapsulated Wells-Dawson polyoxometalates (SEPs) nanobuilding blocks in butanone and esters yielded supramolecular gels showing thermo and photo responsive properties. The gels can be further polymerized if unsaturated esters were used and subsequently electrospinned into nanowires and non-woven mats. The as-prepared non-woven mats have a Young's modulus as high as 542.55 MPa. It is believed that this supramolecular gel is a good platform for polyoxometalates processing. PMID:23666013

  16. Sol-gel encapsulation for controlled drug release and biosensing

    NASA Astrophysics Data System (ADS)

    Fang, Jonathan

    The main focus of this dissertation is to investigate the use of sol-gel encapsulation of biomolecules for controlled drug release and biosensing. Controlled drug release has advantages over conventional therapies in that it maintains a constant, therapeutic drug level in the body for prolonged periods of time. The anti-hypertensive drug Captopril was encapsulated in sol-gel materials of various forms, such as silica xerogels and nanoparticles. The primary objective was to show that sol-gel silica materials are promising drug carriers for controlled release by releasing Captopril at a release rate that is within a therapeutic range. We were able to demonstrate desired release for over a week from Captopril-doped silica xerogels and overall release from Captopril-doped silica nanoparticles. As an aside, the antibiotic Vancomycin was also encapsulated in these porous silica nanoparticles and desired release was obtained for several days in-vitro. The second part of the dissertation focuses on immobilizing antibodies and proteins in sol-gel to detect various analytes, such as hormones and amino acids. Sol-gel competitive immunoassays on antibody-doped silica xerogels were used for hormone detection. Calibration for insulin and C-peptide in standard solutions was obtained in the nM range. In addition, NASA-Ames is also interested in developing a reagentless biosensor using bacterial periplasmic binding proteins (bPBPs) to detect specific biomarkers, such as amino acids and phosphate. These bPBPs were doubly labeled with two different fluorophores and encapsulated in silica xerogels. Ligand-binding experiments were performed on the bPBPs in solution and in sol-gel. Ligand-binding was monitored by fluorescence resonance energy transfer (FRET) between the two fluorophores on the bPBP. Titration data show that one bPBP has retained its ligand-binding properties in sol-gel.

  17. Breeding maintainer lines for hybrid rice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maintainer lines are a component of 3-line hybrid rice production, necessary to perpetuate the male-sterile (MS) line. In practice, it is often the maintainer that is bred with an array of desirable traits, then male-sterility is transferred in through several backcrosses with the new maintainer to...

  18. Dynamics of a DNA Gel

    NASA Astrophysics Data System (ADS)

    Adhikari, Ramesh; Bhattacharya, Aniket; Dogariu, Aristide

    We study in silico the properties of a gel consisting of DNA strands (modeled as semi-flexible chains) and linkers of varying flexibility, length, and topology. These linkers are envisioned and modeled as active components with additional attributes so as to mimic properties of a synthetic DNA gel containing motor proteins. We use Brownian dynamics to directly obtain frequency dependent complex shear moduli of the gel. We further carry out force spectroscopy on these computer generated gels and study the relaxation properties as a function of the important parameters of the model, e.g., densities and relative ratios of the DNAs and the linkers, the average life time of a link, etc. Our studies are relevant for designing synthetic bio-materials for both materials and medical applications.

  19. TOPICAL REVIEW: Polymer gel dosimetry

    NASA Astrophysics Data System (ADS)

    Baldock, C.; De Deene, Y.; Doran, S.; Ibbott, G.; Jirasek, A.; Lepage, M.; McAuley, K. B.; Oldham, M.; Schreiner, L. J.

    2010-03-01

    Polymer gel dosimeters are fabricated from radiation sensitive chemicals which, upon irradiation, polymerize as a function of the absorbed radiation dose. These gel dosimeters, with the capacity to uniquely record the radiation dose distribution in three-dimensions (3D), have specific advantages when compared to one-dimensional dosimeters, such as ion chambers, and two-dimensional dosimeters, such as film. These advantages are particularly significant in dosimetry situations where steep dose gradients exist such as in intensity-modulated radiation therapy (IMRT) and stereotactic radiosurgery. Polymer gel dosimeters also have specific advantages for brachytherapy dosimetry. Potential dosimetry applications include those for low-energy x-rays, high-linear energy transfer (LET) and proton therapy, radionuclide and boron capture neutron therapy dosimetries. These 3D dosimeters are radiologically soft-tissue equivalent with properties that may be modified depending on the application. The 3D radiation dose distribution in polymer gel dosimeters may be imaged using magnetic resonance imaging (MRI), optical-computerized tomography (optical-CT), x-ray CT or ultrasound. The fundamental science underpinning polymer gel dosimetry is reviewed along with the various evaluation techniques. Clinical dosimetry applications of polymer gel dosimetry are also presented.

  20. Topical Review: Polymer gel dosimetry

    PubMed Central

    Baldock, C; De Deene, Y; Doran, S; Ibbott, G; Jirasek, A; Lepage, M; McAuley, K B; Oldham, M; Schreiner, L J

    2010-01-01

    Polymer gel dosimeters are fabricated from radiation sensitive chemicals which, upon irradiation, polymerize as a function of the absorbed radiation dose. These gel dosimeters, with the capacity to uniquely record the radiation dose distribution in three-dimensions (3D), have specific advantages when compared to one-dimensional dosimeters, such as ion chambers, and two-dimensional dosimeters, such as film. These advantages are particularly significant in dosimetry situations where steep dose gradients exist such as in intensity-modulated radiation therapy (IMRT) and stereotactic radiosurgery. Polymer gel dosimeters also have specific advantages for brachytherapy dosimetry. Potential dosimetry applications include those for low-energy x-rays, high-linear energy transfer (LET) and proton therapy, radionuclide and boron capture neutron therapy dosimetries. These 3D dosimeters are radiologically soft-tissue equivalent with properties that may be modified depending on the application. The 3D radiation dose distribution in polymer gel dosimeters may be imaged using magnetic resonance imaging (MRI), optical-computerized tomography (optical-CT), x-ray CT or ultrasound. The fundamental science underpinning polymer gel dosimetry is reviewed along with the various evaluation techniques. Clinical dosimetry applications of polymer gel dosimetry are also presented. PMID:20150687

  1. Alternative imaging modalities for polymer gel dosimetry

    NASA Astrophysics Data System (ADS)

    Jirasek, Andrew

    2010-11-01

    This review summarizes recent work in the area of imaging polymer gel dosimeters using x-ray CT imaging, ultrasound, and radiation-induced changes in gel mechanical properties. In addition, recent work in the area of Raman tomographic imaging of canine bone, in conjunction with past efforts in Raman imaging of polymer gel dosimeters, raises new possibilities for new polymer gel imaging techniques.

  2. Rheological behavior of Slide Ring Gels.

    NASA Astrophysics Data System (ADS)

    Sharma, Vivek; Park, Jong Seung; Park, Jung O.; Srinivasarao, Mohan

    2006-03-01

    Slide ring gels were synthesized by chemically crosslinking, sparsely populated α-cyclodextrin (α-CD) present on the polyrotaxanes consisting of α-CD and polyethylene glycol (PEG). [1] Unlike physically or chemically crosslinked gels, slide ring gels are topological gels where crosslinks can slide along the chain. [2] We investigate the rheological behavior of these gels swollen in water and compare their viscoelastic properties to those of physical and chemical gels. We also study the equilibrium swelling behavior of these gels. [1] Okumura and Ito, Adv. Mater. 2001, 13, 485 [2] C. Zhao et al, J. Phys. Cond. Mat. 2005, 17, S2841

  3. Thixotropic gel for vadose zone remediation

    DOEpatents

    Riha, Brian D.

    2012-07-03

    A thixotropic gel suitable for use in subsurface bioremediation is provided along with a process of using the gel. The thixotropic gel provides a non-migrating injectable substrate that can provide below ground barrier properties. In addition, the gel components provide for a favorable environment in which certain contaminants are preferentially sequestered in the gel and subsequently remediated by either indigenous or introduced microorganisms.

  4. Thixotropic gel for vadose zone remediation

    DOEpatents

    Rhia, Brian D.

    2011-03-01

    A thixotropic gel suitable for use in subsurface bioremediation is provided along with a process of using the gel. The thixotropic gel provides a non-migrating injectable substrate that can provide below ground barrier properties. In addition, the gel components provide for a favorable environment in which certain contaminants are preferentially sequestered in the gel and subsequently remediated by either indigenous or introduced microorganisms.

  5. Thixotropic gel for vadose zone remediation

    DOEpatents

    Riha, Brian D.; Looney, Brian B.

    2015-10-27

    A thixotropic gel suitable for use in subsurface bioremediation is provided along with a process of using the gel. The thixotropic gel provides a non-migrating injectable substrate that can provide below ground barrier properties. In addition, the gel components provide for a favorable environment in which certain contaminants are preferentially sequestered in the gel and subsequently remediated by either indigenous or introduced microorganisms.

  6. Gel placement in fractured systems

    SciTech Connect

    Seright, R.S.

    1995-11-01

    This paper examines several factors that can have an important effect on gel placement in fractured systems, including gelant viscosity, degree of gelation, and gravity. For an effective gel treatment, the conductivity of the fracture must be reduced and a viable flow path must remain open between the wellbore and mobile oil in the reservoir. During placement, the gelant that``leaks off`` from the fracture into the rock plays an important role in determining how well a gel treatment will reduce channeling. For a given volume of gelant injected the distance of gelant leakoff is greater for a viscous gelant than for a low-viscosity gelant. In one method to minimize gelant leakoff, sufficient gelation is designed to occur before the gelant leaves the wellbore. The authors investigated this approach in numerous experiments with both fractured and unfractured cores. They studied Cr(III)/acetate/hydrolyzed polyacrylamide (HPAM), resorcinol/formaldehyde, Cr(III)/xanthan, aluminum/citrate/HPAM, and other gelants and gels with various delay times between gelant preparation and injection. Their results suggest both hope and caution concerning the injection of gels into fractured systems.

  7. Designing for Maintainability and System Availability

    NASA Technical Reports Server (NTRS)

    Lalli, Vincent R.; Packard, Michael H.

    1997-01-01

    The final goal for a delivered system (whether a car, aircraft, avionics box or computer) should be its availability to operate and perform its intended function over its expected design life. Hence, in designing a system, we cannot think in terms of delivering the system and just walking away. The system supplier needs to provide support throughout the operating life of the product. Here, supportability requires an effective combination of reliability, maintainability, logistics and operations engineering (as well as safety engineering) to have a system that is available for its intended use throughout its designated mission lifetime. Maintainability is a key driving element in the effective support and upkeep of the system as well as providing the ability to modify and upgrade the system throughout its lifetime. This paper then, will concentrate on maintainability and its integration into the system engineering and design process. The topics to be covered include elements of maintainability, the total cost of ownership, how system availability, maintenance and logistics costs and spare parts cost effect the overall program costs. System analysis and maintainability will show how maintainability fits into the overall systems approach to project development. Maintainability processes and documents will focus on how maintainability is to be performed and what documents are typically generated for a large scale program. Maintainability analysis shows how trade-offs can be performed for various alternative components. The conclusions summarize the paper and are followed by specific problems for hands-on training.

  8. Space Maintainers in Dentistry: Past to Present

    PubMed Central

    Setia, Vikas; Pandit, Inder Kumar; Srivastava, Nikhil; Gugnani, Neeraj; Sekhon, Harveen Kaur

    2013-01-01

    Early orthodontic interventions are often initiated in the developing dentition to promote favourable developmental changes. Interceptive orthodontic can eliminate or reduce the severity of a developing malocclusion, the complexity of orthodontic treatment, overall treatment time and cost. The safest way to prevent future malocclusions from tooth loss is to place a space maintainer that is effective and durable. An appropriate use of space maintainer is advocated to hold the space until the eruption of permanent teeth. This case report describes the various changing trends in use of space maintainers: conventional band and loop, prefabricated band with custom made loop and glass fibre reinforced composite resins as space maintainers. PMID:24298544

  9. Copolymers For Capillary Gel Electrophoresis

    DOEpatents

    Liu, Changsheng; Li, Qingbo

    2005-08-09

    This invention relates to an electrophoresis separation medium having a gel matrix of at least one random, linear copolymer comprising a primary comonomer and at least one secondary comonomer, wherein the comonomers are randomly distributed along the copolymer chain. The primary comonomer is an acrylamide or an acrylamide derivative that provides the primary physical, chemical, and sieving properties of the gel matrix. The at least one secondary comonomer imparts an inherent physical, chemical, or sieving property to the copolymer chain. The primary and secondary comonomers are present in a ratio sufficient to induce desired properties that optimize electrophoresis performance. The invention also relates to a method of separating a mixture of biological molecules using this gel matrix, a method of preparing the novel electrophoresis separation medium, and a capillary tube filled with the electrophoresis separation medium.

  10. Fundamentals of Polymer Gel Dosimeters

    NASA Astrophysics Data System (ADS)

    McAuley, Kim B.

    2006-12-01

    The recent literature on polymer gel dosimetry contains application papers and basic experimental studies involving polymethacrylic-acid-based and polyacrylamide-based gel dosimeters. The basic studies assess the relative merits of these two most commonly used dosimeters, and explore the effects of tetrakis hydroxymethyl phosphonium chloride (THPC) antioxidant on dosimeter performance. Polymer gel dosimeters that contain THPC or other oxygen scavengers are called normoxic dosimeters, because they can be prepared under normal atmospheric conditions, rather than in a glove box that excludes oxygen. In this review, an effort is made to explain some of the underlying chemical phenomena that affect dosimeter performance using THPC, and that lead to differences in behaviour between dosimeters made using the two types of monomer systems. Progress on the development of new more effective and less toxic dosimeters is also reported.

  11. Sol-gel derived sorbents

    DOEpatents

    Sigman, Michael E.; Dindal, Amy B.

    2003-11-11

    Described is a method for producing copolymerized sol-gel derived sorbent particles for the production of copolymerized sol-gel derived sorbent material. The method for producing copolymerized sol-gel derived sorbent particles comprises adding a basic solution to an aqueous metal alkoxide mixture for a pH.ltoreq.8 to hydrolyze the metal alkoxides. Then, allowing the mixture to react at room temperature for a precalculated period of time for the mixture to undergo an increased in viscosity to obtain a desired pore size and surface area. The copolymerized mixture is then added to an immiscible, nonpolar solvent that has been heated to a sufficient temperature wherein the copolymerized mixture forms a solid upon the addition. The solid is recovered from the mixture, and is ready for use in an active sampling trap or activated for use in a passive sampling trap.

  12. Statistical physics of polymer gels

    NASA Astrophysics Data System (ADS)

    Panyukov, Sergei; Rabin, Yitzhak

    1996-05-01

    This work presents a comprehensive analysis of the statistical mechanics of randomly cross-linked polymer gels, starting from a microscopic model of a network made of instantaneously cross-linked Gaussian chains with excluded volume, and ending with the derivation of explicit expressions for the thermodynamic functions and for the density correlation functions which can be tested by experiments. Using replica field theory we calculate the mean field density in replica space and show that this solution contains statistical information about the behavior of individual chains in the network. The average monomer positions change affinely with macroscopic deformation and fluctuations about these positions are limited to length scales of the order of the mesh size. We prove that a given gel has a unique state of microscopic equilibrium which depends on the temperature, the solvent, the average monomer density and the imposed deformation. This state is characterized by the set of the average positions of all the monomers or, equivalently, by a unique inhomogeneous monomer density profile. Gels are thus the only known example of equilibrium solids with no long-range order. We calculate the RPA density correlation functions that describe the statistical properties of small deviations from the average density, due to both static spatial heterogeneities (which characterize the inhomogeneous equilibrium state) and thermal fluctuations (about this equilibrium). We explain how the deformation-induced anisotropy of the inhomogeneous equilibrium density profile is revealed by small angle neutron scattering and light scattering experiments, through the observation of the butterfly effect. We show that all the statistical information about the structure of polymer networks is contained in two parameters whose values are determined by the conditions of synthesis: the density of cross-links and the heterogeneity parameter. We find that the structure of instantaneously cross

  13. Encapsulation method for maintaining biodecontamination activity

    DOEpatents

    Rogers, Robert D.; Hamilton, Melinda A.; Nelson, Lee O.; Benson, Jennifer; Green, Martin J.; Milner, Timothy N.

    2002-01-01

    A method for maintaining the viability and subsequent activity of microorganisms utilized in a variety of environments to promote biodecontamination of surfaces. One application involves the decontamination of concrete surfaces. Encapsulation of microbial influenced degradation (MID) microorganisms has shown that MID activity is effectively maintained under passive conditions, that is, without manual addition of moisture or nutrients, for an extended period of time.

  14. Encapsulation method for maintaining biodecontamination activity

    DOEpatents

    Rogers, Robert D.; Hamilton, Melinda A.; Nelson, Lee O.; Benson, Jennifer; Green, Martin J.; Milner, Timothy N.

    2006-04-11

    A method for maintaining the viability and subsequent activity of microorganisms utilized in a variety of environments to promote biodecontamination of surfaces. One application involves the decontamination of concrete surfaces. Encapsulation of microbial influenced degradation (MID) microorganisms has shown that MID activity is effectively maintained under passive conditions, that is, without manual addition of moisture or nutrients, for an extended period of time.

  15. 42 CFR 431.230 - Maintaining services.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 4 2010-10-01 2010-10-01 false Maintaining services. 431.230 Section 431.230 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Applicants and Recipients Procedures § 431.230 Maintaining services. (a) If the agency mails the 10-day or...

  16. 42 CFR 431.230 - Maintaining services.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 4 2012-10-01 2012-10-01 false Maintaining services. 431.230 Section 431.230 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Applicants and Beneficiaries Procedures § 431.230 Maintaining services. (a) If the agency mails the 10-day...

  17. Fabricating silver nanoplate/hybrid silica gel glasses and investigating their nonlinear optical absorption behavior

    NASA Astrophysics Data System (ADS)

    Zheng, Chan; Wenzhe, Chen; Xiaoyun, Ye; Cai, Shuguang; Xiao, Xueqing

    2014-03-01

    Silver nanoplate/hybrid silica gel glasses were prepared via the sol-gel technique. Analysis of ultraviolet-visible spectroscopy extinction spectra confirmed the successful incorporation of silver nanoplates into the hybrid silica gel glasses. The silver nanoplate/hybrid silica gel glass composites are completely noncrystalline because of their low doping level compared with that of the silica matrix. The nonlinear optical absorption behavior of the silver nanoplate/hybrid silica gel glass composites was studied via open-aperture Z-scan technique with 4 ns pulse durations at 532 nm and 1064 nm. The nonlinear optical properties of silver nanoplates are maintained after they were introduced into silica gel glasses. Furthermore, the silver nanoplate/hybrid silica gel glasses exhibit intensity-dependent transformation from saturable absorption (SA) to reverse saturable absorption (RSA). The SA behavior at low excitation intensity can be attributed to the bleaching of ground-state surface plasmon resonance absorption induced by the retarded electronic relaxation process in solid-state gel glasses. By contrast, the RSA at high incident influence may have resulted from excited-state absorption and two-photon absorption.

  18. A New Combination of Testosterone and Nestorone Transdermal Gels for Male Hormonal Contraception

    PubMed Central

    Ilani, Niloufar; Roth, Mara Y.; Amory, John K.; Swerdloff, Ronald S.; Dart, Clint; Page, Stephanie T.; Bremner, William J.; Sitruk-Ware, Regine; Kumar, Narender; Blithe, Diana L.

    2012-01-01

    Context: Combinations of testosterone (T) and nestorone (NES; a nonandrogenic progestin) transdermal gels may suppress spermatogenesis and prove appealing to men for contraception. Objective: The objective of the study was to determine the effectiveness of T gel alone or combined with NES gel in suppressing spermatogenesis. Design and Setting: This was a randomized, double-blind, comparator clinical trial conducted at two academic medical centers. Participants: Ninety-nine healthy male volunteers participated in the study. Interventions: Volunteers were randomized to one of three treatment groups applying daily transdermal gels (group 1: T gel 10 g + NES 0 mg/placebo gel; group 2: T gel 10 g + NES gel 8 mg; group 3: T gel 10 g + NES gel 12 mg). Main Outcome Variable: The main outcome variable of the study was the percentage of men whose sperm concentration was suppressed to 1 million/ml or less by 20–24 wk of treatment. Results: Efficacy data analyses were performed on 56 subjects who adhered to the protocol and completed at least 20 wk of treatment. The percentage of men whose sperm concentration was 1 million/ml or less was significantly higher for T + NES 8 mg (89%, P < 0.0001) and T + NES 12 mg (88%, P = 0.0002) compared with T + NES 0 mg group (23%). The median serum total and free T concentrations in all groups were maintained within the adult male range throughout the treatment period. Adverse effects were minimal in all groups. Conclusion: A combination of daily NES + T gels suppressed sperm concentration to 1 million/ml or less in 88.5% of men, with minimal adverse effects, and may be further studied as a male transdermal hormonal contraceptive. PMID:22791756

  19. Nonlinear elasticity of alginate gels

    NASA Astrophysics Data System (ADS)

    Hashemnejad, Seyed Meysam; Kundu, Santanu

    Alginate is a naturally occurring anionic polysaccharide extracted from brown algae. Because of biocompatibility, low toxicity, and simple gelation process, alginate gels are used in biomedical and food applications. Here, we report the rheological behavior of ionically crosslinked alginate gels, which are obtained by in situ gelation of alginates with calcium salts, in between two parallel plates of a rheometer. Strain stiffening behavior was captured using large amplitude oscillatory shear (LAOS) experiments. In addition, negative normal stress was observed for these gels, which has not been reported earlier for any polysaccharide networks. The magnitude of negative normal stress increases with applied strain and can exceed that of the shear stress at large strain. Rheological results fitted with a constitutive model that considers both stretching and bending of chains indicate that nonlinearity is likely related to the stretching of the chains between the crosslink junctions. The results provide an improved understanding of the deformation mechanism of ionically crosslinked alginate gel and the results will be important in developing synthetic extracellular matrix (ECM) from these materials.

  20. Calculating Percent Gel For Process Control

    NASA Technical Reports Server (NTRS)

    Webster, Charles Neal; Scott, Robert O.

    1988-01-01

    Reaction state of thermosetting resin tracked to assure desired properties. Rate of gel determined as function of temperature by measuring time to gel of part of graphite fabric impregnated with Hexcel R120 (or equivalent) phenolic resin.

  1. Generation of 3D Collagen Gels with Controlled Diverse Architectures.

    PubMed

    Doyle, Andrew D

    2016-01-01

    Rat tail collagen solutions have been used as polymerizable in vitro three dimensional (3D) extracellular matrix (ECM) gels for single and collective cell migration assays as well as spheroid formation. Factors such as ECM concentration, pH, ionic concentration, and temperature can alter collagen polymerization and ECM architecture. This unit describes how to generate 3D collagen gels that have distinct architectures ranging from a highly reticular meshwork of short thin fibrils with small pores to a loose matrix consisting of stiff, parallel-bundled long fibrils by changing collagen polymerization temperature. This permits analysis of 3D cell migration in different ECM architectures found in vivo while maintaining a similar ECM concentration. Also included are collagen labeling techniques helpful for ECM visualization during live fluorescence imaging. © 2016 by John Wiley & Sons, Inc. PMID:27580704

  2. Stable and responsive fluorescent carbon nanotube silica gels

    SciTech Connect

    Dattelbaum, Andrew M; Gupta, Gautam; Doorn, Stephen K; Duque, Juan G

    2010-05-03

    Here we report a general route to prepare silica nanocomposite gels doped with fluorescent single walled carbon nanotubes (SWNT). We show that tetramethylorthosilicate (TMOS) vapors can be used to gel an aqueous suspension of surfactant-wrapped SWNT while maintaining fluorescence from the semiconducting nanotubes. The vapor phase silica process is performed at room temperature and is simple, reproducible, relatively quick, and requires no dilution of SWNT dispersions. However, exposure of aqueous SWNT suspensions to TMOS vapors resulted in an acidification of the suspension prior to gelation that caused a decrease in the emission signal from sodium dodecylsulfate (SDS) wrapped SWNT. We also show that although the SWNT are encapsulated in silica the emission signal from the encapsulated SWNT may be attenuated by exposing the nanocomposites to small aromatic molecules known to mitigate SWNT emission. These results demonstrate a new route for the preparation of highly luminescent SWNT/silica composite materials that are potentially useful for future sensing applications.

  3. Mechanisms maintaining grassland biodiversity and ecosystem stability

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ecologists need to know how particular processes influence biodiversity and ecosystem stability. We demonstrate how data from biodiversity-ecosystem functioning experiments can be used to identify and quantify the classes of mechanisms maintaining biodiversity and ecosystem stability. We predicted...

  4. Ecology: Tribal Warfare Maintains Microbial Diversity.

    PubMed

    Greig, Duncan; Goddard, Matthew

    2015-07-20

    When two tribes of Myxococcus bacteria attack each other, the most numerous usually wins. Established colonies can therefore resist invaders by outnumbering them. This shows how positive frequency dependence can maintain diversity across spatially structured environments. PMID:26196492

  5. Control system maintains compartment at constant temperature

    NASA Technical Reports Server (NTRS)

    Lindberg, J. G.

    1966-01-01

    Gas-filled permeable insulating material maintains an enclosed compartment at a uniform temperature. The material is interposed between the two walls of a double-walled enclosure surrounding the compartment.

  6. An Introduction to Reliability and Maintainability.

    ERIC Educational Resources Information Center

    Berridge, C. R.

    1984-01-01

    Discusses the need to include studies of reliability and maintainability during the design of any system. Topic areas addressed include availability calculations, complex systems and standby redundancy, availability and malfunction levels, design techniques, fault trees, functional maintenance, and others. (DH)

  7. Older Runners Can Maintain Their 'Fuel Efficiency'

    MedlinePlus

    ... of oxygen consumption is what researchers call "running economy." They found that even though the gait of ... still maintain youthful energy levels, or good running economy, while exercising. "There's good evidence that it's never ...

  8. Maintainability planning for the Space Station

    NASA Technical Reports Server (NTRS)

    Egan, G. R.

    1986-01-01

    The planned NASA Space Station, which is expected to have many years of on-orbit operation, for the first time confronts spacecraft designers with major questions of maintainability in design. A Maintainability Guidelines Document has been distributed to all Space Station Definition and Preliminary Design personnel of the Space Station Program Office. Trade studies are being performed to determine the most economical balance between initial (reliability) cost and life cycle cost (crew time and replacement hardware) costs.

  9. Maintainability program requirements for space systems

    NASA Technical Reports Server (NTRS)

    1987-01-01

    This document is established to provide common general requirements for all NASA programs to: design maintainability into all systems where maintenance is a factor in system operation and mission success; and ensure that maintainability characteristics are developed through the systems engineering process. These requirements are not new. Design for ease of maintenance and minimization of repair time have always been fundamental requirements of the systems engineering process. However, new or reusable orbital manned and in-flight maintainable unmanned space systems demand special emphasis on maintainability, and this document has been prepared to meet that need. Maintainability requirements on many NASA programs differ in phasing and task emphasis from requirements promulgated by other Government agencies. This difference is due to the research and development nature of NASA programs where quantities produced are generally small; therefore, the depth of logistics support typical of many programs is generally not warranted. The cost of excessive maintenance is very high due to the logistics problems associated with the space environment. The ability to provide timely maintenance often involves safety considerations for manned space flight applications. This document represents a basic set of requirements that will achieve a design for maintenance. These requirements are directed primarily at manned and unmanned orbital space systems. To be effective, maintainability requirements should be tailored to meet specific NASA program and project needs and constraints. NASA activities shall invoke the requirements of this document consistent with program planning in procurements or on inhouse development efforts.

  10. Characteristics of platelet gels combined with silk

    PubMed Central

    Pallotta, Isabella; Kluge, Jonathan A.; Moreau, Jodie; Calabrese, Rossella

    2014-01-01

    Platelet gel, a fibrin network containing activated platelets, is widely used in regenerative medicine due the capacity of platelet-derived growth factors to accelerate and direct healing processes. However, limitations to this approach include poor mechanical properties, relatively rapid degradation, and the lack of control of release of growth factors at the site of injection. These issues compromise the ability of platelet gels for sustained function in regenerative medicine. In the present study, a combination of platelet gels with silk fibroin gel was studied to address the above limitations. Mixing sonicated silk gels with platelet gels extended the release of growth factors without inhibiting gel forming ability. The released growth factors were biologically active and their delivery was modified further by manipulation of the charge of the silk protein. Moreover, the silk gel augmented both the rheological properties and compressive stiffness of the platelet gel, tuned by the silk concentration and/or silk/platelet gel ratio. Silk-platelet gel injections in nude rats supported enhanced cell infiltration and blood vessel formation representing a step towards new platelet gel formulations with enhanced therapeutic impact. PMID:24480538

  11. Spring-loaded polymeric gel actuators

    DOEpatents

    Shahinpoor, M.

    1995-02-14

    Spring-loaded electrically controllable polymeric gel actuators are disclosed. The polymeric gels can be polyvinyl alcohol, polyacrylic acid, or polyacrylamide, and are contained in an electrolytic solvent bath such as water plus acetone. The action of the gel is mechanically biased, allowing the expansive and contractile forces to be optimized for specific applications. 5 figs.

  12. A clarified gel for crystal growth

    NASA Technical Reports Server (NTRS)

    Barber, P. G.; Simpson, N. R.

    1985-01-01

    A procedure for preparing clarified sodium silicate gels suitable for crystal growth is described. In the method described here, the silicate stock is clarified by pretreating it with cation exchange resins before preparing the gels. Also, a modified recipe is proposed for preparing gels to achieve improved transparency.

  13. Characteristics of platelet gels combined with silk.

    PubMed

    Pallotta, Isabella; Kluge, Jonathan A; Moreau, Jodie; Calabrese, Rossella; Kaplan, David L; Balduini, Alessandra

    2014-04-01

    Platelet gel, a fibrin network containing activated platelets, is widely used in regenerative medicine due the capacity of platelet-derived growth factors to accelerate and direct healing processes. However, limitations to this approach include poor mechanical properties, relatively rapid degradation, and the lack of control of release of growth factors at the site of injection. These issues compromise the ability of platelet gels for sustained function in regenerative medicine. In the present study, a combination of platelet gels with silk fibroin gel was studied to address the above limitations. Mixing sonicated silk gels with platelet gels extended the release of growth factors without inhibiting gel-forming ability. The released growth factors were biologically active and their delivery was modified further by manipulation of the charge of the silk protein. Moreover, the silk gel augmented both the rheological properties and compressive stiffness of the platelet gel, tuned by the silk concentration and/or silk/platelet gel ratio. Silk-platelet gel injections in nude rats supported enhanced cell infiltration and blood vessel formation representing a step towards new platelet gel formulations with enhanced therapeutic impact. PMID:24480538

  14. Spring-loaded polymeric gel actuators

    DOEpatents

    Shahinpoor, Mohsen

    1995-01-01

    Spring-loaded electrically controllable polymeric gel actuators are disclosed. The polymeric gels can be polyvinyl alcohol, polyacrylic acid, or polyacrylamide, and are contained in an electrolytic solvent bath such as water plus acetone. The action of the gel is mechanically biased, allowing the expansive and contractile forces to be optimized for specific applications.

  15. The Swelling of Olympic Gels

    NASA Astrophysics Data System (ADS)

    Lang, Michael; Fischer, Jakob; Werner, Marco; Sommer, Jens-Uwe

    2014-03-01

    The swelling equilibrium of Olympic gels is studied by Monte Carlo Simulations. We observe that gels consisting of flexible cyclic molecules of a higher degree of polymerization N show a smaller equilibrium swelling degree Q ~N - 0 . 28φ0- 0 . 72 for the same monomer volume fraction φ0 at network preparation. This observation is explained by a disinterpenetration process of overlapping non-concatenated polymers upon swelling. In the limit of a sufficiently large number of concatenations per cyclic molecule we expect that the equilibrium degree of swelling becomes proportional to φ0- 1 / 2 independent of N. Our results challenge current textbook models for the equilibrium degree of swelling of entangled polymer networks. Now at: Bio Systems Analysis Group, Jena Centre for Bioinformatics (JCB) and Department for Mathematics and Computer Sciences, Friedrich Schiller University of Jena, 07743 Jena, Germany.

  16. Supercoiling transformation of chemical gels.

    PubMed

    Asai, Makoto; Katashima, Takuya; Sakai, Takamasa; Shibayama, Mitsuhiro

    2015-09-28

    The swelling/deswelling behavior of chemical gels has been an unsolved problem disputed over for a long time. The Obukhov-Rubinstein-Colby model depicts the influence that swelling/deswelling has on elasticity, but its physical picture is too complicated to be sufficiently validated by experiment. In this study, we use molecular dynamics simulation to verify the validity of the molecular picture of network strands predicted by the Obukhov-Rubinstein-Colby model. We conclude that the physical picture of the Obukhov-Rubinstein-Colby model is reasonable, and furthermore the simulation can reveal the details of conformational changes in network strands during the supercoiling transformation. Our findings not only reveal the validity, but also give a better understanding of the dynamics of the swelling/deswelling behavior of chemical gels. PMID:26279149

  17. Nanocrystal/sol-gel nanocomposites

    DOEpatents

    Klimov, Victor L.; Petruska, Melissa A.

    2010-05-25

    The present invention is directed to a process for preparing a solid composite having colloidal nanocrystals dispersed within a sol-gel matrix, the process including admixing colloidal nanocrystals with an amphiphilic polymer including hydrophilic groups selected from the group consisting of --COOH, --OH, --SO.sub.3H, --NH.sub.2, and --PO.sub.3H.sub.2 within a solvent to form an alcohol-soluble colloidal nanocrystal-polymer complex, admixing the alcohol-soluble colloidal nanocrystal-polymer complex and a sol-gel precursor material, and, forming the solid composite from the admixture. The present invention is also directed to the resultant solid composites and to the alcohol-soluble colloidal nanocrystal-polymer complexes.

  18. Microchannel gel electrophoretic separation systems and methods for preparing and using

    DOEpatents

    Herr, Amy; Singh, Anup K; Throckmorton, Daniel J

    2013-09-03

    A micro-analytical platform for performing electrophoresis-based immunoassays was developed by integrating photopolymerized cross-linked polyacrylamide gels within a microfluidic device. The microfluidic immunoassays are performed by gel electrophoretic separation and quantifying analyte concentration based upon conventional polyacrylamide gel electrophoresis (PAGE). To retain biological activity of proteins and maintain intact immune complexes, native PAGE conditions were employed. Both direct (non-competitive) and competitive immunoassay formats are demonstrated in microchips for detecting toxins and biomarkers (cytokines, c-reactive protein) in bodily fluids (serum, saliva, oral fluids). Further, a description of gradient gels fabrication is included, in an effort to describe methods we have developed for further optimization of on-chip PAGE immunoassays. The described chip-based PAGE immunoassay method enables immunoassays that are fast (minutes) and require very small amounts of sample (less than a few microliters). Use of microfabricated chips as a platform enables integration, parallel assays, automation and development of portable devices.

  19. Microchannel gel electrophoretic separation systems and methods for preparing and using

    DOEpatents

    Herr, Amy E; Singh, Anup K; Throckmorton, Daniel J

    2015-02-24

    A micro-analytical platform for performing electrophoresis-based immunoassays was developed by integrating photopolymerized cross-linked polyacrylamide gels within a microfluidic device. The microfluidic immunoassays are performed by gel electrophoretic separation and quantifying analyte concentration based upon conventional polyacrylamide gel electrophoresis (PAGE). To retain biological activity of proteins and maintain intact immune complexes, native PAGE conditions were employed. Both direct (non-competitive) and competitive immunoassay formats are demonstrated in microchips for detecting toxins and biomarkers (cytokines, c-reactive protein) in bodily fluids (serum, saliva, oral fluids). Further, a description of gradient gels fabrication is included, in an effort to describe methods we have developed for further optimization of on-chip PAGE immunoassays. The described chip-based PAGE immunoassay method enables immunoassays that are fast (minutes) and require very small amounts of sample (less than a few microliters). Use of microfabricated chips as a platform enables integration, parallel assays, automation and development of portable devices.

  20. Ciprofloxacin monoolein water gels as implants for the treatment of chronic osteomyelitis: In vitro characterization

    PubMed Central

    Sombié, Bavouma Charles; Yameogo, Josias Gérard; Semdé, Rasmané; Henschel, Viviane; Amighi, Karim; Goole, Jonathan

    2014-01-01

    This work investigated the possibility of using the biodegradable gentamicin-monoolein-water gels as models, in order to obtain a similar sustained release of ciprofloxacin hydrochloride. Four gels containing antibiotics were prepared and were examined with regard to their physicochemical properties and in vitro drug release characteristics. Ciprofloxacin, unlike gentamicin, which was dissolved in the matrix, was in dispersed form. However, despite its insolubility, microscopic observation, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and X-ray diffraction showed that the developed gel was in the cubic liquid crystalline structure and have maintained their ability to progressively release ciprofloxacin. ciprofloxacin-monoolein-water (5:80:15% w/w), which released in vitro approximately 85% of ciprofloxacin after 16 days could possibly be considered as an alternative to a gentamicin-monoolein-water gel for the treatment of chronic osteomyelitis. PMID:25364693

  1. Ciprofloxacin monoolein water gels as implants for the treatment of chronic osteomyelitis: In vitro characterization.

    PubMed

    Sombié, Bavouma Charles; Yameogo, Josias Gérard; Semdé, Rasmané; Henschel, Viviane; Amighi, Karim; Goole, Jonathan

    2014-10-01

    This work investigated the possibility of using the biodegradable gentamicin-monoolein-water gels as models, in order to obtain a similar sustained release of ciprofloxacin hydrochloride. Four gels containing antibiotics were prepared and were examined with regard to their physicochemical properties and in vitro drug release characteristics. Ciprofloxacin, unlike gentamicin, which was dissolved in the matrix, was in dispersed form. However, despite its insolubility, microscopic observation, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and X-ray diffraction showed that the developed gel was in the cubic liquid crystalline structure and have maintained their ability to progressively release ciprofloxacin. ciprofloxacin-monoolein-water (5:80:15% w/w), which released in vitro approximately 85% of ciprofloxacin after 16 days could possibly be considered as an alternative to a gentamicin-monoolein-water gel for the treatment of chronic osteomyelitis. PMID:25364693

  2. Porous alumina scaffold produced by sol-gel combined polymeric sponge method

    NASA Astrophysics Data System (ADS)

    Hasmaliza, M.; Fazliah, M. N.; Shafinaz, R. J.

    2012-09-01

    Sol gel is a novel method used to produce high purity alumina with nanometric scale. In this study, three-dimensional porous alumina scaffold was produced using sol-gel polymeric sponge method. Briefly, sol gel alumina was prepared by evaporation and polymeric sponge cut to designated sizes were immersed in the sol gel followed by sintering at 1250 and 1550°C. In order to study the cell interaction, the porous alumina scaffold was sterilized using autoclave prior to Human Mesenchymal Stem Cells (HMSCs) seeding on the scaffold and the cell proliferation was assessed by alamarBlue® assay. SEM results showed that during the 21 day period, HMSCs were able to attach on the scaffold surface and the interconnecting pores while maintaining its proliferation. These findings suggested the potential use of the porous alumina produced as a scaffold for implantation procedure.

  3. Crosslinked polymer gel electrolytes based on polyethylene glycol methacrylate and ionic liquid for lithium battery applications

    SciTech Connect

    Liao, Chen; Sun, Xiao-Guang; Dai, Sheng

    2013-01-01

    Gel polymer electrolytes were synthesized by copolymerization polyethylene glycol methyl ether methacrylate with polyethylene glycol dimethacrylate in the presence of a room temperature ionic liquid, methylpropylpyrrolidinium bis(trifluoromethanesulfonyl)imide (MPPY TFSI). The physical properties of gel polymer electrolytes were characterized by thermal analysis, impedance spectroscopy, and electrochemical tests. The ionic conductivities of the gel polymer electrolytes increased linearly with the amount of MPPY TFSI and were mainly attributed to the increased ion mobility as evidenced by the decreased glass transition temperatures. Li||LiFePO4 cells were assembled using the gel polymer electrolytes containing 80 wt% MPPY TFSI via an in situ polymerization method. A reversible cell capacity of 90 mAh g 1 was maintained under the current density of C/10 at room temperature, which was increased to 130 mAh g 1 by using a thinner membrane and cycling at 50 C.

  4. Multiscale modeling of polyelectrolyte gels

    NASA Astrophysics Data System (ADS)

    Wallmersperger, Thomas; Wittel, Falk K.; Kröplin, Bernd H.

    2006-03-01

    Electrolyte polymer gels are a very attractive class of actuation materials with remarkable electronic and mechanical properties having a great similarity to biological contractile tissues. They consist of a polymer network with ionizable groups and a liquid phase with mobile ions. Absorption and delivery of solvent lead to a considerably large change of volume. Due to this capability, they can be used as actuators for technical applications, where large swelling and shrinkage is desired. In the present work chemically and electrically stimulated polymer gels in a solution bath are investigated. To describe the different complicated phenomena occurring in these gels adequately, the modeling can be conducted on different scales. Therefore, models based on the statistical theory and porous media theory, as well as a multi-field model and a discrete element formulation are derived. A refinement of the different theories from global macroscopic to microscopic are presented in this paper: The statistical theory is a macroscopic theory capable to describe the global swelling or bending e.g. of a gel film, while the general theory of porous media (TPM) is a macroscopic continuum theory which is based on the theory of mixtures extended by the concept of volume fractions. The TPM is a homogenized model, i.e. all geometrical and physical quantities can be seen as statistical averages of the real quantities. The presented chemo-electro-mechanical multi-field formulation is a mesoscopic theory. It is capable of giving the concentrations and the electric potential in the whole domain. Finally the (micromechanical) discrete element (DE) theory is employed. In this case, the continuum is represented by distributed particles with local interaction relations combined with balance equations for the chemical field. This method is predestined for problems involving large displacements, strains and discontinuities. The presented formulations are compared and conclusions on their

  5. Super-absorbency and phase transition of gels in physiological salt solutions

    NASA Astrophysics Data System (ADS)

    Zhang, Yong-Qing; Tanaka, Toyoichi; Shibayama, Mitsuhiro

    1992-11-01

    IONIC gels with the ability to absorb many times their dry weight of water have found widespread use as absorbents in medical, chemical and agricultural applications1. The dramatic swelling power of these super-absorbent gels results from both the electrostatic repulsion between the charges on the polymer chains, and the osmotic pressure of the counter-ions2. In salt solutions such as saline, urine or blood, however, excess Na+ and Cl- ions screen the polymer charges and eliminate the osmotic imbalance, effectively changing the properties of the material to that of a non-ionic gel3: this greatly diminishes the swelling power, and hence the utility of these materials under physiological conditions. Here we report the development of a system combining a non-ionic gel with ionized surfactants, which shows super-absorbent behaviour even in the presence of salt. In water, the hydrophobic gel facilitates the formation of spherical surfactant micelles, which mimic the charged sites of an ionic gel. As the salt concentration is increased, the micelles become rod-like, maintaining the electrostatic repulsion along the polymer chains and thereby preserving the swelling power of the gel.

  6. Quality change of apple slices coated with Aloe vera gel during storage.

    PubMed

    Song, Hye-Yeon; Jo, Wan-Shin; Song, Nak-Bum; Min, Sea C; Song, Kyung Bin

    2013-06-01

    Fresh-cut apples are easily susceptible to browning and microbial spoilage. In this study, an edible coating prepared from Aloe vera gel containing antibrowning solution was applied to preserve the quality of fresh-cut apples during storage. Fresh-cut apples were treated with both an Aloe vera gel and an Aloe vera gel containing 0.5% cysteine and then stored at 4 °C for 16 d. The color, firmness, weight loss, soluble solid content, titratable acidity, microbial analysis, and sensory evaluation were analyzed during storage. Fresh-cut apples coated with the Aloe vera gel showed delayed browning and reduced weight loss and softening compared to the control. The Aloe vera gel coating was also effective in reducing the populations of the total aerobic bacteria and yeast and molds. In particular, Aloe vera gel containing 0.5% cysteine was most effective in delaying browning and the reduction of microbial populations among the treatments. These results suggest that an Aloe vera gel coating can be used for maintaining the quality of fresh-cut apples. PMID:23647574

  7. Selective gel system for permeability profile control

    SciTech Connect

    Shu, P.

    1990-02-27

    This patent describes a process for closing pores in a more permeable zone of a formation. It comprises: placing into an aqueous solution a first composition sufficient to form ex-situ a size selective, shear thinning first gel which comprises a xanthan biopolymer, and a transitional metal ion; placing into the aqueous solution a second composition sufficient to form thermally a second in-situ gel which is substantially more resistant to formation conditions than the first gel. The composition comprises an aldehyde, and a phenolic compound; allowing the aqueous solution sufficient time to form the ex-situ gel; and injecting the aqueous solution containing the gel into the permeable zone where it reheals, is heated by the formation and thereafter forms a solid gel substantially more resistant to formation conditions than the first gel.

  8. Automated Methods to Maintain Aircraft Separation

    NASA Technical Reports Server (NTRS)

    Lauderdale, Todd

    2011-01-01

    The air traffic control system in the United States has a great track-record for safety. As more aircraft enter the system at a given time, the situation becomes more complex though. Researchers at NASA are attempting to leverage advances in many fields including optimization, data mining, and numerical modeling of systems to improve the air-transportation system maintaining safety while increasing throughput and reducing delays. This talk will give a brief overview of the research at NASA towards modernizing the air-transportation system. It will then focus on the specific area of automation tools for maintaining physical separation between aircraft known as Separation Assurance.

  9. 7 CFR 1430.508 - Maintaining records.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS DAIRY PRODUCTS Dairy Market Loss Assistance Program § 1430.508 Maintaining records. Dairy operations making application for benefits under this... after the date of the cash payment to dairy operations under this program....

  10. 7 CFR 1430.508 - Maintaining records.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS DAIRY PRODUCTS Dairy Market Loss Assistance Program § 1430.508 Maintaining records. Dairy operations making application for benefits under this... after the date of the cash payment to dairy operations under this program....

  11. 7 CFR 1430.508 - Maintaining records.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS DAIRY PRODUCTS Dairy Market Loss Assistance Program § 1430.508 Maintaining records. Dairy operations making application for benefits under this... after the date of the cash payment to dairy operations under this program....

  12. 7 CFR 1430.508 - Maintaining records.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS DAIRY PRODUCTS Dairy Market Loss Assistance Program § 1430.508 Maintaining records. Dairy operations making application for benefits under this... after the date of the cash payment to dairy operations under this program....

  13. 7 CFR 1430.508 - Maintaining records.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS DAIRY PRODUCTS Dairy Market Loss Assistance Program § 1430.508 Maintaining records. Dairy operations making application for benefits under this... after the date of the cash payment to dairy operations under this program....

  14. 7 CFR 786.112 - Maintaining records.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Agriculture Regulations of the Department of Agriculture (Continued) FARM SERVICE AGENCY, DEPARTMENT OF AGRICULTURE SPECIAL PROGRAMS DAIRY DISASTER ASSISTANCE PAYMENT PROGRAM (DDAP-III) § 786.112 Maintaining... after the date of payment to their dairy operations under this program. Destruction of the records...

  15. 7 CFR 786.112 - Maintaining records.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Agriculture Regulations of the Department of Agriculture (Continued) FARM SERVICE AGENCY, DEPARTMENT OF AGRICULTURE SPECIAL PROGRAMS DAIRY DISASTER ASSISTANCE PAYMENT PROGRAM (DDAP-III) § 786.112 Maintaining... after the date of payment to their dairy operations under this program. Destruction of the records...

  16. Maintaining Interest in Operator Requal Training.

    ERIC Educational Resources Information Center

    Lapp, H. J., Jr.

    A study reviewed operator training programs at Oyster Creek Nuclear Generating Station to determine their interface with plant operations and to devise new ways of maintaining interest in requalification (requal) training. The operator training review committee that was formed to implement the review documented over 100 issues and concerns…

  17. Obtaining, Maintaining, and Advancing Your Fitness Certification

    ERIC Educational Resources Information Center

    Pierce, Patricia; Herman, Susan

    2004-01-01

    Public awareness of health, fitness, and exercise has increased and the fitness industry has expanded in recent years. Yet, ironically, the health of our nation continues to deteriorate. Now more than ever there is the need for qualified fitness professionals to help individuals to improve or maintain health and fitness. Since fitness…

  18. Maintaining and Repairing. CAP Job Function.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. National Center for Research in Vocational Education.

    This Job Function Booklet (Maintaining and Repairing) is one of the 14 components (see note) of the Career Alert Planning (CAP) program, a set of individualized materials designed to help participants find out about themselves and about the kind of work for which they are suited. In this program, participants become acquainted with occupations…

  19. Maintaining Hope in the Face of Evil.

    ERIC Educational Resources Information Center

    Miller, Geri

    2002-01-01

    P. G. Zimbardo (2001) and M. E. P. Seligman (in an interview with S. Carpenter, 2001) discuss evil and hope in response to the September 11, 2001, disaster. The implications for counseling are presented with an emphasis on how counselors can maintain hope for themselves and their clients in the face of evil. (Author)

  20. Maintaining ideal body weight counseling sessions

    SciTech Connect

    Brammer, S.H.

    1980-10-09

    The purpose of this program is to provide employees with the motivation, knowledge and skills necessary to maintain ideal body weight throughout life. The target audience for this program, which is conducted in an industrial setting, is the employee 40 years of age or younger who is at or near his/her ideal body weight.

  1. How Do Positive Views Maintain Life Satisfaction?

    ERIC Educational Resources Information Center

    Wu, Chia-Huei; Tsai, Ying-Mei; Chen, Lung Hung

    2009-01-01

    This study proposes three mediation pathways to explain how the positive views (perceived control, optimism and self-enhancement) proposed by Cummins and Nistico (Journal of Happiness Studies 3:37-69 2002) maintain life satisfaction. The three pathways were enhancing self-esteem, reducing have-want discrepancy and changing importance perceptions.…

  2. Metal-silica sol-gel materials

    NASA Technical Reports Server (NTRS)

    Stiegman, Albert E. (Inventor)

    2002-01-01

    The present invention relates to a single phase metal-silica sol-gel glass formed by the co-condensation of a transition metal with silicon atoms where the metal atoms are uniformly distributed within the sol-gel glass as individual metal centers. Any transition metal may be used in the sol-gel glasses. The present invention also relates to sensor materials where the sensor material is formed using the single phase metal-silica sol-gel glasses. The sensor materials may be in the form of a thin film or may be attached to an optical fiber. The present invention also relates to a method of sensing chemicals using the chemical sensors by monitoring the chromatic change of the metal-silica sol-gel glass when the chemical binds to the sensor. The present invention also relates to oxidation catalysts where a metal-silica sol-gel glass catalyzes the reaction. The present invention also relates to a method of performing oxidation reactions using the metal-silica sol-gel glasses. The present invention also relates to organopolymer metal-silica sol-gel composites where the pores of the metal-silica sol-gel glasses are filled with an organic polymer polymerized by the sol-gel glass.

  3. Intermittent use of an antimicrobial hand gel for reducing soap-induced irritation of health care personnel.

    PubMed

    Newman, J L; Seitz, J C

    1990-06-01

    We evaluated the effects of an antimicrobial hand gel (containing 60% ethanol plus emollients) on skin condition when used as a supplement to handwashing. Volunteers washed their hands 10 times per day for 5 days with a bar soap. Between washings one hand was treated with 1.0 ml of the gel while the other hand was untreated. By the conclusion of the study the gel-treated hands exhibited significantly lower (p less than 0.05) photographic scores for cracking, scaling, and erythema (redness), the major symptoms of dry, irritated skin. The gel treatment also helped to maintain normal skin hydration levels as measured by transepidermal water loss and skin impedance. By reducing soap-induced irritation, an alcohol gel with the appropriate emollients can help eliminate a major deterrent to handwashing among health care personnel. PMID:2363539

  4. Formulation development and evaluation of innovative two-polymer (SR-2P) bioadhesive vaginal gel.

    PubMed

    Podaralla, Satheesh; Alt, Carsten; Shankar, Gita N

    2014-08-01

    The main objective of this investigation was to study the feasibility of developing a vaginal bioadhesive microbicide using a SRI's proprietary two-polymer gel platform (SR-2P). Several formulations were prepared with different combinations of temperature-sensitive polymer (Pluronic® F-127) and mucoadhesive polymer (Noveon® AA-1), producing gels of different characteristics. Prototype polymeric gels were evaluated for pH, osmolality, buffering capacity, and viscosity under simulated vaginal semen dilutions, and bioadhesivity using ex vivo mini pig vaginal tissues and texture analyzer. The pH of the polymeric gel formulations ranged from 5.1 to 6.4; the osmolality varied from 13 to 173 mOsm. Absolute viscosity ranged from 513 to 3,780 cPs, and was significantly reduced (1.5- to 3-fold) upon incubation with simulated vaginal and semen fluid mixture. Among the tested gels (indicated in the middle row as a molar ratio of a mixture of Noveon vs. Pluronic), only SR-2P retained gel structure upon dilution with simulated fluids and mild simulated coital stress. The pH of the SR-2P gel was maintained at about 4.6 in simulated vaginal fluid and also showed high peak force of adhesion in mini pig vaginal tissue. Furthermore, SR-2P gel caused no or only minimal irritation in a mouse vaginal irritation model. The results of this preliminary study demonstrated the potential application of SR-2P gel as a vaginal microbicide vehicle for delivery of anti-HIV agents. PMID:24781671

  5. Ultrafast Sol-Gel Synthesis of Graphene Aerogel Materials

    SciTech Connect

    Lim, Mathew; Hu, Matthew; Manandhar, Sandeep; Sakshaug, Avery; Strong, Adam; Riley, Leah; Pauzauskie, Peter J.

    2015-12-01

    Graphene aerogels derived from graphene-oxide (GO) starting materials recently have been shown to exhibit a combination of high electrical conductivity, chemical stability, and low cost that has enabled a range of electrochemical applications. Standard synthesis protocols for manufacturing graphene aerogels require the use of sol-gel chemical reactions that are maintained at high temperatures for long periods of time ranging from 12 hours to several days. Here we report an ultrafast, acid-catalyzed sol-gel formation process in acetonitrile in which wet GO-loaded gels are realized within 2 hours at temperatures below 45°C. Spectroscopic and electrochemical analysis following supercritical drying and pyrolysis confirms the reduction of the GO in the aerogels to sp2 carbon crystallites with no residual carbon–nitrogen bonds from the acetonitrile or its derivatives. This rapid synthesis enhances the prospects for large-scale manufacturing of graphene aerogels for use in numerous applications including sorbents for environmental toxins, support materials for electrocatalysis, and high-performance electrodes for electrochemical capacitors and solar cells.

  6. Automated apparatus for producing gradient gels

    DOEpatents

    Anderson, Norman L.

    1986-01-01

    Apparatus for producing a gradient gel which serves as a standard medium for a two-dimensional analysis of proteins, the gel having a density gradient along its height formed by a variation in gel composition, with the apparatus including first and second pumping means each including a plurality of pumps on a common shaft and driven by a stepping motor capable of providing small incremental changes in pump outputs for the gel ingredients, the motors being controlled, by digital signals from a digital computer, a hollow form or cassette for receiving the gel composition, means for transferring the gel composition including a filler tube extending near the bottom of the cassette, adjustable horizontal and vertical arms for automatically removing and relocating the filler tube in the next cassette, and a digital computer programmed to automatically control the stepping motors, arm movements, and associated sensing operations involving the filling operation.

  7. Automated apparatus for producing gradient gels

    DOEpatents

    Anderson, N.L.

    1983-11-10

    Apparatus for producing a gradient gel which serves as a standard medium for a two-dimensional analysis of proteins, the gel having a density gradient along its height formed by a variation in gel composition, with the apparatus including first and second pumping means each including a plurality of pumps on a common shaft and driven by a stepping motor capable of providing small incremental changes in pump outputs for the gel ingredients, the motors being controlled, by digital signals from a digital computer, a hollow form or cassette for receiving the gel composition, means for transferring the gel composition including a filler tube extending near the bottom of the cassette, adjustable horizontal and vertical arms for automatically removing and relocating the filler tube in the next cassette, and a digital computer programmed to automatically control the stepping motors, arm movements, and associated sensing operations involving the filling operation.

  8. Selective gel system for permeability profile control

    SciTech Connect

    Shu, P.

    1990-10-16

    This patent describes a selective gel for closing pores in a more permeable zone of a formation. It comprises: an aqueous solution of a first composition sufficient to form ex-situ a size selective, shear thinning first gel which comprises a xanthan biopolymer, and a transitional metal ion; and an aqueous solution of a second composition sufficient to form thermally a second in-situ gel that which comprises and aldehyde, and a phenolic compound which solutions are combined and allowed to form a shearable, rehealable ex-situ gel which can be injected into the permeable zone where it reheals when heated by the formation and thereafter forms a solid gel substantially more resistant to formation conditions than the first gel.

  9. Managing Self-Governing Primary Schools in the Locally Maintained, Grant-Maintained and Private Sectors.

    ERIC Educational Resources Information Center

    Bell, Les; And Others

    1996-01-01

    Discusses a study that surveyed heads of locally maintained, grant-maintained, and private sector (British) primary schools concerning their management styles. Questionnaire and interview data suggest that autonomous primary schools are characterized by collective decision making and high job satisfaction levels. Private sector school heads'…

  10. GEM printer: 3D gel printer for free shaping of functional gel engineering materials

    NASA Astrophysics Data System (ADS)

    Furukawa, Hidemitsu; Muroi, Hisato; Yamamoto, Kouki; Serizawa, Ryo; Gong, Jin

    2013-04-01

    In the past decade, several high-strength gels have been developed. These gels are expected to use as a kind of new engineering materials in the fields of industry and medical as substitutes to polyester fibers, which are materials of artificial blood vessels. The gels have both low surface friction and well permeability due to a large amount of water absorbed in the gels, which are superiority of the gels compering to the polyester fibers. It is, however, difficult for gels to be forked structure or cavity structure by using cutting or mold. Consequently, it is necessary to develop the additive manufacturing device to synthesize and mode freely gels at the same time. Here we try to develop an optical 3D gel printer that enables gels to be shaped precisely and freely. For the free forming of high-strength gels, the 1st gels are ground to particles and mixed with 2nd pregel solution, and the mixed solution is gelled by the irradiation of UV laser beam through an optical fiber. The use of the optical fiber makes one-point UV irradiation possible. Since the optical fiber is controlled by 3D-CAD, the precise and free molding in XYZ directions is easily realized. We successfully synthesized tough gels using the gel printer.

  11. Characteristics of polyacrylamide gel with THPC and Turnbull Blue gel dosimeters evaluated using optical tomography

    NASA Astrophysics Data System (ADS)

    Pilařová (Vávrů), Kateřina; Kozubíková, Petra; Šolc, Jaroslav; Spěváček, Václav

    2014-11-01

    The purpose of this study was to compare characteristics of radiochromic gel - Turnbull Blue gel (TB gel) with polymer gel - polyacrylamide gel and tetrakis hydroxymethyl phosphonium chloride (PAGAT) using optical tomography. Both types of gels were examined in terms of dose sensitivity, dose response linearity and background value of spectrophotometric absorbance. The calibration curve was obtained for 60Co irradiation performed on Gammacell 220 at predefined gamma dose levels between 0 and 140 Gy for TBG and 0-15 Gy for PAGAT. To measure relative dose distributions from stereotactic irradiation, dosimeters were irradiated on Leksell Gamma Knife Perfexion. The cylindrical glass housings filled with gel were attached to the stereotactic frame. They were exposed with single shot and 16 mm collimator by 65 Gy to a 50% prescription isodose for TB gel and 4 Gy to a 50% prescription isodose for PAGAT. Evaluations of dosimeters were performed on an UV-vis Spectrophotometer Helios β and an optical cone beam homemade tomography scanner with a 16-bit astronomy CCD camera with a set of color filters. The advantages and potential disadvantages for both types of gel dosimeters were summarized. Dose distribution in central slice and measured profiles of 16 mm shot shows excellent correspondence with treatment planning system Leksell GammaPlan® for both PAGAT and Turnbull Blue gels. Gel dosimeters are suitable for steep dose gradient verification. An optical tomography evaluation method is successful. Dose response characteristics of TB gel and PAGAT gel are presented.

  12. Autophagy maintains stemness by preventing senescence.

    PubMed

    García-Prat, Laura; Martínez-Vicente, Marta; Perdiguero, Eusebio; Ortet, Laura; Rodríguez-Ubreva, Javier; Rebollo, Elena; Ruiz-Bonilla, Vanessa; Gutarra, Susana; Ballestar, Esteban; Serrano, Antonio L; Sandri, Marco; Muñoz-Cánoves, Pura

    2016-01-01

    During ageing, muscle stem-cell regenerative function declines. At advanced geriatric age, this decline is maximal owing to transition from a normal quiescence into an irreversible senescence state. How satellite cells maintain quiescence and avoid senescence until advanced age remains unknown. Here we report that basal autophagy is essential to maintain the stem-cell quiescent state in mice. Failure of autophagy in physiologically aged satellite cells or genetic impairment of autophagy in young cells causes entry into senescence by loss of proteostasis, increased mitochondrial dysfunction and oxidative stress, resulting in a decline in the function and number of satellite cells. Re-establishment of autophagy reverses senescence and restores regenerative functions in geriatric satellite cells. As autophagy also declines in human geriatric satellite cells, our findings reveal autophagy to be a decisive stem-cell-fate regulator, with implications for fostering muscle regeneration in sarcopenia. PMID:26738589

  13. Maintaining professional resilience through group restorative supervision.

    PubMed

    Wallbank, Sonya

    2013-08-01

    Restorative clinical supervision has been delivered to over 2,500 professionals and has shown to be highly effective in reducing burnout, stress and increasing compassion satisfaction. Demand for the programme has shown that a sustainable model of implementation is needed for organisations who may not be able to invest in continued individual sessions. Following the initial six sessions, group restorative supervision has been developed and this paper reports on the programme's success in maintaining and continuing to improve compassion satisfaction, stress and burnout through the process of restorative group supervision. This means that organisations can continue to maintain the programme once the initial training has been completed and have confidence within the restorative group supervision to support professionals in managing the emotional demands of their role. The restorative groups have also had inadvertent positive benefits in workplace functioning. The paper outlines how professionals have been able to use this learning to support them in being more effective. PMID:23986988

  14. Self-Pumping Active Gel

    NASA Astrophysics Data System (ADS)

    Wu, Kun-Ta; Hishamunda, Jean Bernard; Fraden, Seth; Dogic, Zvonimir

    Isotropic active gels are the network which is consist of cross-linked building blocks and the structure of which changes randomly and isotropically with time. Dogic et. al. show that pairs of anti-parallel microtubules form extensile bundles, which merge, extend, and buckle. In an unconfined system, the dynamics of these bundles causes spontaneous turbulent-like flow driven by motion of microscopic molecular motors. We found that confining these active gels in a millimeter sized toroids causes a transition into a new dynamical state characterized by circulation currents persisting for hours until ATP is depleted. We show how toroid dimensions impact the properties of self-organized circular currents, how directions of circulation can be designed by engineering ratchet-shaped boundaries, and how circulations of connected toroids can be either synchronized or antisynchronized. Furthermore, we demonstrate that the flow rate in the circulation is independent of curvature and length of flow path. The flow rate persists for centimeters without decay, disregarding conventional pipe flow resistance. Such findings pave the path to self-pumping pipe transport and performing physical work with biological system.

  15. [Electron microscopy study of artificial vitreous gel].

    PubMed

    Ehgartner, E M; Schmut, O; Hofmann, H

    1986-04-01

    Artificial gels prepared from Cu2+-ions and hyaluronic acid were studied in the electron microscope and compared with the native vitreous body. Additionally, the authors attempted to produce transparent gels from the native constituents of the vitreous body, namely collagen and hyaluronic acid. Mixing of solutions of these constituents formed no gels but white precipitates. The ultrastructure of these precipitates was also studied in the electron microscope. PMID:3723971

  16. Gel time of calcium acrylate grouting material.

    PubMed

    Han, Tong-Chun

    2004-08-01

    Calcium acrylate is a polymerized grout, and can polymerize in an aqueous solution. The polymerization reaction utilizes ammonium persulfate as a catalyst and sodium thiosulfate as the activator. Based on the theory of reaction kinetics, this study on the relation between gel time and concentration of activator and catalyst showed that gel time of calcium acrylate is inversely proportional to activator and catalyst concentration. A formula of gel time is proposed, and an example is provided to verify the proposed formula. PMID:15236477

  17. Device Maintains Water At The Triple Point

    NASA Technical Reports Server (NTRS)

    West, J. W.; Burkett, C. G.

    1988-01-01

    Inexpensive device maintains water at 0.01 degree C for 10 weeks or longer. New device consists of four basic assemblies; small, commercial chest freezer containing insulated water tank; insulated copper cell holder; "ice switch" for cycling freezer compressor and externally-mounted air pump for circulation. Access hole in freezer lid allows triple point measurements without opening lid. Modified freezer used to calibrate standard platinum resistance thermomenters.

  18. Issues in Purchasing and Maintaining Intrinsic Standards

    SciTech Connect

    PETTIT,RICHARD B.; JAEGER,KLAUS; EHRLICH,CHARLES D.

    2000-09-12

    Intrinsic standards are widely used in the metrology community because they realize the best level uncertainty for many metrology parameters. For some intrinsic standards, recommended practices have been developed to assist metrologists in the selection of equipment and the development of appropriate procedures in order to realize the intrinsic standard. As with the addition of any new standard, the metrology laboratory should consider the pros and cons relative to their needs before purchasing the standard so that the laboratory obtains the maximum benefit from setting up and maintaining these standards. While the specific issues that need to be addressed depend upon the specific intrinsic standard and the level of realization, general issues that should be considered include ensuring that the intrinsic standard is compatible with the laboratory environment, that the standard is compatible with the current and future workload, and whether additional support standards will be required in order to properly maintain the intrinsic standard. When intrinsic standards are used to realize the best level of uncertainty for a specific metrology parameter, they usually require critical and important maintenance activities. These activities can including training of staff in the system operation, as well as safety procedures; performing periodic characterization measurements to ensure proper system operation; carrying out periodic intercomparisons with similar intrinsic standards so that proper operation is demonstrated; and maintaining control or trend charts of system performance. This paper has summarized many of these important issues and therefore should be beneficial to any laboratory that is considering the purchase of an intrinsic standard.

  19. Interventions to Maintain Mobility: What Works?

    PubMed Central

    Ross, Lesley A.; Schmidt, Erica L.; Ball, Karlene

    2012-01-01

    Mobility, in broad terms, includes everything from the ability to move within your immediate environment (e.g., get out of bed) to the ability to drive across the country. Mobility is essential to maintaining independence and wellbeing, particularly for older adults. This is highlighted by the large number of interventions developed for older adults with the goal of maintaining such mobility. The current paper reviews the state of the science with respect to mobility interventions. Inclusion criteria for the review were: (1) articles must have been peer-reviewed; (2) interventions were evaluated in a randomized controlled trial (RCT); (3) studies included a mobility outcome such as lifespace, driving, or walking ability, (4) studies included a sample of healthy community-dwelling older adults (e.g., not investigations of disease conditions); and (5) studies reported enough empirical data and detail such that results could potentially be replicated. Three main types of interventions were identified: cognitive training, educational interventions, and exercise interventions. A detailed summary and evaluation of each type of intervention, and the current evidence regarding its effectiveness in maintaining mobility, are discussed. Several interventions show clear evidence of effectiveness, and thus are prime areas for translation of results to the older population. Needs and issues for future intervention research are also detailed. PMID:23083492

  20. Alertness maintaining tasks (AMTs) while driving.

    PubMed

    Oron-Gilad, Tal; Ronen, Adi; Shinar, David

    2008-05-01

    We evaluated the effectiveness of alertness maintaining tasks (AMTs) on driver performance, subjective feelings, and psychophysiological state in monotonous simulated driving in two experiments. In the first experiment, 12 professional truck drivers participated in five sessions of simulated driving: driving only, driving with one of three AMTs (counterbalanced), and driving while listening to music. AMTs were not equally effective in maintaining alertness. The trivia AMT prevented driving performance deterioration, and increased alertness (measured by standardized HRV). The choice reaction time AMT was least demanding but also increased subjective sleepiness and reduced arousal (measured by alpha/beta ratio). The working memory AMT caused a significant decrement in driving speed, increased subjective fatigue, and was regarded by the participants as detrimental to driving. Trivia was preferred by the majority of the drivers over the other two AMTs. Experiment 2 further examined the utility of the trivia AMT. When the drivers engaged in the trivia AMT they maintained better driving performance and perceived the driving duration as shorter than the control condition. The two experiments demonstrated that AMTs can have a positive effect on alertness. The effect is localized in the sense that it does not persist beyond the period of the AMT activation. PMID:18460351

  1. Colloidal gel and its application in tissue engineering

    NASA Astrophysics Data System (ADS)

    Xie, Baojun

    2005-12-01

    Scope and method of study. Three dimensional, porous polymer scaffolds are fabricated by direct writing of colloidal gels. This work focuses on both the processing of colloidal gel and assembly of the scaffold structures as well as characterization of cytotoxicity and protein release kinetics. Specifically, rheological and elastic properties of the colloidal gels are probed as a function of solids loading and binder concentration. Porous scaffolds are characterized by optical and electron microscopy. In vitro studies include cell mortality after six weeks culture on passive scaffolds, model protein release profiles from scaffolds, and quantitative measurement of protein activity upon release from the scaffolds by chemotaxis. Findings and conclusions. The polymer colloidal gels formulated with acrylic latex particles and Pluronic F127 copolymer binder have pseudoplastic with yield stress rheology. Increases in solids loading and Pluronic concentration cause increased viscosity, elastic modulus, and yield stress. The rheology and rapid recovery of yield allow for flow through a deposition nozzle of the direct write toot and rapid setting of the extrudate to maintain the deposited structure. Scaffolds with a wide variety of porosity are fabricated. Because of the aqueous and low temperature nature of the process, bioactive molecules such as proteins are readily incorporated into the scaffold either in their original form or encapsulated in chitosan nanoparticles and subsequently released without denaturation and in a controlled fashion. Protein release rate is dependent on both the degree of coalescence of the scaffold material and the molecular weight of the chitosan nanoparticles. Protein inclusion and subsequent release is demonstrated using BSA and PDGF-BB. The scaffolds fabricated are non-cytotoxic as confirmed by QEC6 cell culture. Heterogeneous scaffolds with localized regions of dissolved species are demonstrated to illustrate the capability to assembly

  2. Flexible polyester cellulose paper supercapacitor with a gel electrolyte.

    PubMed

    Karthika, Prasannan; Rajalakshmi, Natarajan; Dhathathreyan, Kaveripatnam S

    2013-11-11

    A low-cost polyester cellulose paper has been used as a substrate for a flexible supercapacitor device that contains aqueous carbon nanotube ink as the electrodes and a polyvinyl alcohol (PVA)-based gel as the electrolyte. Gel electrolytes have attracted much interest due to their solvent-holding capacity and good film-forming capability. The electrodes are characterized for their conductivity and morphology. Because of its high conductivity, the conductive paper is studied in supercapacitor applications as active electrodes and as separators after coating with polyvinylidene fluoride. Carbon nanotubes deposited on porous paper are more accessible to ions in the electrolyte than those on flat substrates, which results in higher power density. A simple fabrication process is achieved and paper supercapacitors are tested for their performance in both aqueous and PVA gel electrolytes by using galvanostatic and cyclic voltammetry methods. A high specific capacitance of 270 F g(-1) and an energy density value of 37 W h kg(-1) are achieved for devices with PVA gel electrolytes. Furthermore, this device can maintain excellent specific capacitance even under high currents. This is also confirmed by another counter experiment with aqueous sulfuric acid as the electrolyte. The cycle life, one of the most critical parameters in supercapacitor operations, is found to be excellent (6000 cycles) and less than 0.5 % capacitance loss is observed. Moreover, the supercapacitor device is flexible and even after twisting does not show any cracks or evidence of breakage, and shows almost the same specific capacitance of 267 F g(-1) and energy density of 37 W h kg(-1) . This work suggests that a paper substrate can be a highly scalable and low-cost solution for high-performance supercapacitors. PMID:24155269

  3. Conducting Polymer Electrodes for Gel Electrophoresis

    PubMed Central

    Bengtsson, Katarina; Nilsson, Sara; Robinson, Nathaniel D.

    2014-01-01

    In nearly all cases, electrophoresis in gels is driven via the electrolysis of water at the electrodes, where the process consumes water and produces electrochemical by-products. We have previously demonstrated that π-conjugated polymers such as poly(3,4-ethylenedioxythiophene) (PEDOT) can be placed between traditional metal electrodes and an electrolyte to mitigate electrolysis in liquid (capillary electroosmosis/electrophoresis) systems. In this report, we extend our previous result to gel electrophoresis, and show that electrodes containing PEDOT can be used with a commercial polyacrylamide gel electrophoresis system with minimal impact to the resulting gel image or the ionic transport measured during a separation. PMID:24586761

  4. Functional behavior of isotropic magnetorheological gels

    NASA Astrophysics Data System (ADS)

    Venkateswara Rao, P.; Maniprakash, S.; Srinivasan, S. M.; Srinivasa, A. R.

    2010-08-01

    Magnetorheological (MR) gels are a new class of soft polymers whose properties can be controlled using a magnetic field. The functional effectiveness of these gels depends on their magnetic controllability. In this paper, an experimental investigation on the functional behavior of a particular type of magnetorheological gels under dynamic and static shear conditions in the presence of a magnetic field is studied. MR gels are prepared with micron sized polarizable carbonyl iron particles interspersed in a polymer matrix gel. The compliance of this magnetic gel can be varied under the influence of an external magnetic field. Since dynamical mechanical analysis tests are difficult to conduct in the presence of large deformations of the order of 50% and strong magnetic fields, a free decay test apparatus is designed and fabricated for obtaining the magnetic field dependent shearing response under dynamic conditions at room temperature. It is observed that a significant change in the elastic modulus occurs in the gels under a magnetic field in the range of 0.1-0.4 T. However, no significant change in the damping ratio is observed under various magnitudes of magnetic field. It is shown that the increase in shear modulus of this kind of magnetic composite gel could be as high as 59% of the zero field value for a gel prepared with 50% by weight of carbonyl iron particles.

  5. Ionic liquid based multifunctional double network gel

    NASA Astrophysics Data System (ADS)

    Ahmed, Kumkum; Higashihara, Tomoya; Arafune, Hiroyuki; Kamijo, Toshio; Morinaga, Takashi; Sato, Takaya; Furukawa, Hidemitsu

    2015-04-01

    Gels are a promising class of soft and wet materials with diverse application in tissue engineering and bio-medical purpose. In order to accelerate the development of gels, it is required to synthesize multi-functional gels of high mechanical strength, ultra low surface friction and suitable elastic modulus with a variety of methods and new materials. Among many types of gel ionic gel made from ionic liquids (ILs) could be used for diverse applications in electrochemical devices and in the field of tribology. IL, a promising materials for lubrication, is a salt with a melting point lower than 100 °C. As a lubricant, ILs are characterized by an extremely low vapor pressure, high thermal stability and high ion conductivity. In this work a novel approach of making double network DN ionic gel using IL has been made utilizing photo polymerization process. A hydrophobic monomer Methyl methacrylate (MMA) has been used as a first network and a hydrophobic IL monomer, N,N-diethyl-N-(2-mthacryloylethyl)-N-methylammonium bistrifluoromethylsulfonyl)imide (DEMM-TFSI) has been used as a second network using photo initiator benzophenon and crosslinker triethylene glycol dimethacrylate (TEGDMA). The resulting DN ionic gel shows transparency, flexibility, high thermal stability, good mechanical toughness and low friction coefficient value which can be a potential candidate as a gel slider in different mechanical devices and can open a new area in the field of gel tribology.

  6. Structure of chitosan gels mineralized by sorption

    NASA Astrophysics Data System (ADS)

    Modrzejewska, Z.; Skwarczyńska, A.; Douglas, T. E. L.; Biniaś, D.; Maniukiewicz, W.; Sielski, J.

    2015-10-01

    The paper presents the structural studies of mineralized chitosan hydrogels. Hydrogels produced by using sodium beta-glycerophosphate (Na-β-GP) as a neutralizing agent. Mineralization was performed method "post loading", which consisted in sorption to the gels structure Ca ions. In order to obtain - in the structure of gels - compounds similar to the hydroxyapatites present naturally in bone tissue, gels after sorption were modified in: pH 7 buffer and sodium hydrogen phosphate. In order to determine the structural properties of the gels, the following methods were used: infrared spectroscopy with Fourier transformation, FTIR, X-ray diffractometry, XRD, scanning electron microscopy, SEM.

  7. Effect of ozonated oil and chlorhexidine gel on plaque induced gingivitis: A randomized control clinical trial

    PubMed Central

    Indurkar, Maya Sanjeev; Verma, Renu

    2016-01-01

    Background: Several chemotherapeutic agents have been developed to prevent gingivitis and its progression into periodontitis. In this present study, the efficacy of ozonated oil and chlorhexidine gel was assessed and compared on plaque induced gingivitis. Aim: To evaluate the effect of ozonated oil on plaque induced gingivitis and to compare its efficacy with chlorhexidine gel. Materials and Methods: A total of 20 subjects, aged from 18 to 65 years, with plaque-induced gingivitis were selected from the outpatient Department of Periodontology, Government Dental College and Hospital, Aurangabad, for this study. They were divided randomly into the test or ozonated oil group (Group I) and the control or chlorhexidine gel group (Group II) with 10 subjects in each group. Subjects were randomly assigned to massage their gingiva thrice a day for 3 weeks with ozonated oil (test), and chlorhexidine gel (control). Plaque index and gingival index scores were recorded for the 20 subjects at baseline and after 3 weeks. Results: Ozonated oil (Group I) and chlorhexidine gel (Group II) groups showed statistically significant differences with respect to plaque index and gingival index, from the baseline to 3 weeks (P < 0.001 in both). But the difference between Group I and Group II, at the end of the study period, was not statistically significant with respect to the plaque index and gingival index. Conclusions: The ozonated oil and chlorhexidine gel, both can be used as an effective agent in maintaining and improving gingival health. PMID:27041835

  8. Stacking gels: A method for maximising output for pulsed-field gel electrophoresis.

    PubMed

    Heng, See Kah; Heng, Chua Kek; Puthucheary, S D

    2009-01-01

    Pulsed field gel electrophoresis (PFGE), the gold standard of molecular typing methods, has a major disadvantage of an unusually long electrophoretic time. From the original protocol of 6 days, it was modified to 3 days and subsequently to a single day. We describe the procedure of stacking five to six gels one on top of another in order to increase and maximize the output in a shorter time without compromising the resolution and reproducibility. All the variables that affect pulsed field gels during electrophoresis were taken into consideration. We firstly optimized the parameters to be used and secondly determined whether stacking of five to six gels had any effect on the molecular separation during electrophoresis in comparison with a single gel run. DNA preparation, restriction, electrophoresis, staining and gel documentation was carried out based on previously published methods. Gels were analysed using BioNumerics and dice coefficient and unweighted pair group methods were used to generate dendrograms based on 1.5% tolerance values. Identical band profiles and band resolution-separation were seen in the PFGE patterns with single gel and multiple stacking gels. Cluster analysis further strengthened the fact that results from stacking gels were reproducible and comparable with a single gel run. This method of stacking gels saves time and maximizes the output at the same time. The run time for a single gel was about 28 hours, but with six stacked gels the run time was 54 hours compared with 28 x 6 = 168 hours if they were run separately as single gels thus saving time of 67.86%. Beside the big factor of saving time, stacking gels save resources (electricity, reagents, water, chemicals and working time) by increasing the sample throughput in a shorter time without compromising on quality of data. But optimization of working parameters is vital depending on the PFGE system used. PMID:19384038

  9. Terpolymer smart gels: synthesis and characterizations

    NASA Astrophysics Data System (ADS)

    Bag, Dibyendu S.; Alam, Sarfaraz; Mathur, G. N.

    2004-10-01

    Two smart terpolymer gels, MS-1 and MS-2, were synthesized such that the same gel can respond to more than one external environmental condition, such as pH, temperature, solvent composition, electric field. So two terpolymers gels of vinyl monomers such as sodium acrylate, acrylamide and N-isopropyl acrylamide were synthesized by using ammonium persulfate (APS) as an initiator, N,N,N',N'-tetramethyl ethylene diamine (TMEDA) as an accelerator and methylene bisacrylamide as a cross-linker. These terpolymers were characterized by elemental and Fourier transform infrared analysis. The swelling behavior of these terpolymer smart gels was evaluated by changing the pH, temperature and solvent composition. The variation of the swelling behavior with time was evaluated in an aqueous medium at room temperature. The time taken for maximum swelling (tm) was about 20 min for the gel MS-2. However the tm value for the gel MS-1 is higher than that of MS-2. The swelling behavior remains almost unchanged over a temperature range of 22-50 °C for both the gels. The discontinuous volume transitions were observed at pH 7.6 and 8.2 for the two gels, MS-1 and MS-2, respectively. The gel MS-1 suddenly shrinks below and swells above pH 7.6. Correspondingly, the pH is 8.2 for the case of MS-2. Volume transitions in an acetone-water mixture were also observed for these gels. The swelling behaviors of these two smart gels are almost parallel above the 40% acetone concentration.

  10. Calcium Alginate Gels as Stem Cell Matrix – Making Paracrine Stem Cell Activity Available for Enhanced Healing after Surgery

    PubMed Central

    Schmitt, Andreas; Rödel, Philipp; Anamur, Cihad; Seeliger, Claudine; Imhoff, Andreas B.; Herbst, Elmar; Vogt, Stephan; van Griensven, Martijn; Winter, Gerhard; Engert, Julia

    2015-01-01

    Regeneration after surgery can be improved by the administration of anabolic growth factors. However, to locally maintain these factors at the site of regeneration is problematic. The aim of this study was to develop a matrix system containing human mesenchymal stem cells (MSCs) which can be applied to the surgical site and allows the secretion of endogenous healing factors from the cells. Calcium alginate gels were prepared by a combination of internal and external gelation. The gelling behaviour, mechanical stability, surface adhesive properties and injectability of the gels were investigated. The permeability of the gels for growth factors was analysed using bovine serum albumin and lysozyme as model proteins. Human MSCs were isolated, cultivated and seeded into the alginate gels. Cell viability was determined by AlamarBlue assay and fluorescence microscopy. The release of human VEGF and bFGF from the cells was determined using an enzyme-linked immunoassay. Gels with sufficient mechanical properties were prepared which remained injectable through a syringe and solidified in a sufficient time frame after application. Surface adhesion was improved by the addition of polyethylene glycol 300,000 and hyaluronic acid. Humans MSCs remained viable for the duration of 6 weeks within the gels. Human VEGF and bFGF was found in quantifiable concentrations in cell culture supernatants of gels loaded with MSCs and incubated for a period of 6 weeks. This work shows that calcium alginate gels can function as immobilization matrices for human MSCs. PMID:25793885

  11. Poly(aryl ether) Dendrons with Monopyrrolotetrathiafulvalene Unit-Based Organogels exhibiting Gel-Induced Enhanced Emission (GIEE).

    PubMed

    Liu, Yucun; Lei, Wenwei; Chen, Tie; Jin, Longyi; Sun, Guangyan; Yin, Bingzhu

    2015-10-19

    A series of poly(aryl ether) dendrons with a monopyrrolo-tetrathiafulvalene unit linked through an acyl hydrazone linkage were designed and synthesized as low molecular mass organogelators (LMOGs). Two of the dendrons could gelate the aromatic solvents and some solvent mixtures, but the others could not gel all solvents tested except for n-pentanol. A subtle change on the molecular structure produces a great influence on the gelation behavior. Note that the dendrons could form the stable gel in the DMSO/water mixture without thermal treatment and could also form the binary gel with fullerene (C60 ) in toluene. The formed gels undergo a reversible gel-sol phase transition upon exposure to external stimuli, such as temperature and chemical oxidation/reduction. A number of experiments (SEM, FTIR spectroscopy, (1) H NMR spectroscopy, and UV/Vis absorption spectroscopy, and XRD) revealed that these dendritic molecules self-assembled into elastically interpenetrating one-dimensional fibrillar aggregates and maintain rectangular molecular-packing mode in organogels. The hydrogen bonding, π-π, and donor-acceptor interactions were found to be the main driving forces for formation of the gels. Moreover, the gel system exhibited gel-induced enhanced emission (GIEE) property in the visible region in spite of the absence of a conventional fluorophore unit and the fluorescence was effectively quenched by introduction of C60 . PMID:26471439

  12. Visual Recognition of Aliphatic and Aromatic Amines Using a Fluorescent Gel: Application of a Sonication-Triggered Organogel.

    PubMed

    Pang, Xuelei; Yu, Xudong; Lan, Haichuang; Ge, Xiaoting; Li, Yajuan; Zhen, Xiaoli; Yi, Tao

    2015-06-24

    A naphthalimide-based fluorescent gelator (N1) containing an alkenyl group has been designed and characterized. This material is able to gelate alcohols via a precipitate-to-gel transformation when triggered with ultrasound for less than 2 min (S-gel). The gelation process in n-propanol was studied by means of absorption, fluorescence, and IR spectra, scanning electron microscopy (SEM) images, and X-ray diffraction patterns. The fluorescence intensity of N1 decreased during the gelation process in a linear relationship with the sonication time. The S-gel of N1 could be used to sense aliphatic and aromatic amines by measuring the change in the signal output. For example, the addition of propylamine to the S-gel of N1 resulted in a dramatic enhancement of the fluorescence intensity, accompanied by a gel-to-sol transition. On the contrary, when the S-gel of N1 was treated with aromatic amines such as aniline, fluorescence was quenched and there was no gel collapse. The sensing mechanisms were studied by (1)H NMR, small-angle X-ray scattering, SEM and spectroscopic experiments. It is proposed that isomerization of the alkenyl group of N1 from the trans to cis form occurs when the S-gel is treated with propylamine, resulting in a gel-sol transition. However, the aromatic aniline molecules prefer to insert into the gel networks of N1 via hydrogen-bonding and charge-transfer interactions, maintaining the gel state. As potential applications, testing strips of N1 were prepared to detect aniline. PMID:26040296

  13. Laboratory services: regaining and maintaining control.

    PubMed

    Lee, Graham R; Fitzgibbon, Maria C; O'Shea, Paula

    2016-06-13

    Purpose - After implementing an internal quality control (IQC) programme, the purpose of this paper is to maintain the requisite analytical performance for clinical laboratory staff, thereby safeguarding patient test results for their intended medical purpose. Design/methodology/approach - The authors address how quality can be maintained and if lost, how it can be regained. The methodology is based on the experience working in clinical laboratory diagnostics and is in accord with both international accreditation requirements and laboratory best practice guidelines. Findings - Monitoring test performance usually involves both prospective and retrospective IQC data analysis. The authors present a number of different approaches together with software tools currently available and emerging, that permit performance monitoring at the level of the individual analyser, across analysers and laboratories (networks). The authors make recommendations on the appropriate response to IQC rule warnings, failures and metrics that indicate analytical control loss, that either precludes further analysis, or signifies deteriorating performance and eventual unsuitability. The authors provide guidance on systematic troubleshooting, to identify undesirable performance and consider risk assessment preventive measures and continuous quality improvement initiatives; e.g., material acceptance procedures, as tools to help regain and maintain analytical control and minimise potential for patient harm. Practical implications - The authors provide a template for use by laboratory scientific personnel that ensures the optimal monitoring of analytical test performance and response when it changes undesirably. Originality/value - The proposed template has been designed to meet the International Organisation for Standardisation for medical laboratories ISO15189:2012 requirements and therefore includes the use of External Quality Assessment and patient results data, as an adjunct to IQC data. PMID

  14. Identifying Crucial Parameter Correlations Maintaining Bursting Activity

    PubMed Central

    Doloc-Mihu, Anca; Calabrese, Ronald L.

    2014-01-01

    Recent experimental and computational studies suggest that linearly correlated sets of parameters (intrinsic and synaptic properties of neurons) allow central pattern-generating networks to produce and maintain their rhythmic activity regardless of changing internal and external conditions. To determine the role of correlated conductances in the robust maintenance of functional bursting activity, we used our existing database of half-center oscillator (HCO) model instances of the leech heartbeat CPG. From the database, we identified functional activity groups of burster (isolated neuron) and half-center oscillator model instances and realistic subgroups of each that showed burst characteristics (principally period and spike frequency) similar to the animal. To find linear correlations among the conductance parameters maintaining functional leech bursting activity, we applied Principal Component Analysis (PCA) to each of these four groups. PCA identified a set of three maximal conductances (leak current, Leak; a persistent K current, K2; and of a persistent Na+ current, P) that correlate linearly for the two groups of burster instances but not for the HCO groups. Visualizations of HCO instances in a reduced space suggested that there might be non-linear relationships between these parameters for these instances. Experimental studies have shown that period is a key attribute influenced by modulatory inputs and temperature variations in heart interneurons. Thus, we explored the sensitivity of period to changes in maximal conductances of Leak, K2, and P, and we found that for our realistic bursters the effect of these parameters on period could not be assessed because when varied individually bursting activity was not maintained. PMID:24945358

  15. Viscoelastic Properties of Vitreous Gel

    NASA Astrophysics Data System (ADS)

    Pirouz Kavehpour, H.; Sharif-Kashani, Pooria

    2010-11-01

    We studied the rheological properties of porcine vitreous humor using a stressed-control shear rheometer. All experiments were performed in a closed environment at body temperature to mimic in-vivo conditions. We modeled the creep deformation using a two-element retardation spectrum model. By associating each element of the model to an individual biopolymeric system in the vitreous gel, a separate response to the applied stress was obtained from each component. The short time scale was associated with the collagen structure, while the longer time scale was related to the microfibrilis and hyaluronan network. We were able to distinguish the role of each main component from the overall rheological properties. Knowledge of this correlation enables us to relate the physical properties of vitreous to its pathology, as well as optimize surgical procedures such as vitrectomy.

  16. Gel transitions in colloidal suspensions

    NASA Astrophysics Data System (ADS)

    Bergenholtz, J.; Fuchs, M.

    1999-12-01

    The idealized mode-coupling theory (MCT) is applied to colloidal systems interacting via short-range attractive interactions of Yukawa form. At low temperatures, MCT predicts a slowing down of the local dynamics and ergodicity-breaking transitions. The non-ergodicity transitions share many features with the colloidal gel transition, and are proposed to be the source of gelation in colloidal systems. Previous calculations of the phase diagram are complemented with additional data for shorter ranges of the attractive interaction, showing that the path of the non-ergodicity transition line is then unimpeded by the gas-liquid critical curve at low temperatures. Particular attention is given to the critical non-ergodicity parameters; this is motivated by recent experimental measurements. An asymptotic model is developed, valid for dilute systems of spheres interacting via strong short-range attractions, and is shown to capture all aspects of the low-temperature MCT non-ergodicity transitions.

  17. Polyphenoloxidases immobilized in organic gels: Properties and applications in the detoxification of aromatic compounds

    SciTech Connect

    Crecchio, C.; Ruggiero, P.; Pizzigallo, M.D.R.

    1995-12-20

    Gelatine gels originate from water in oil microemulsions in which the ternary system consists of isooctane/sulfosuccinic acid bis [2-ethyl hexyl] ester/water; the solubilization of gelatin in the water pool of these microemulsions transforms them into viscous gels in which it is possible to cosolubilize various reactive molecules. These gels were used to immobilize two phenoloxidases, a laccase from Trametes versicolor and a tyrosinase from mushroom. The best balance between gel retention and catalytic activity was reached at a gelatine concentration of 2.5% (w/v) in the case of tyrosinase, while laccase immobilization was independent of gelatine concentration. Both enzymes kept the same optimum pH as the corresponding soluble controls, while a partial loss of activity was observed when they were immobilized. Immobilized enzymes showed an increased stability when incubated for several days at 4 C with a very low release from the gels in the incubation solutions. The immobilization of tyrosinase and of laccase enhanced stability to thermal inactivation. Furthermore, gel-entrapped tyrosinase was almost completely preserved from proteolysis: more than 80% of the activity was maintained, while only 25% of the soluble control activity was detected after the same proteolytic treatments. A column packed with gel-immobilized tyrosinase was used to demonstrate that enzymes immobilized with this technique may be reused several times in the same reaction without loosing their efficiency. Finally, gel-entrapped tyrosinase and laccase were capable of removing naturally occurring and xenobiotic aromatic compounds from aqueous suspensions with different degrees of efficiency.

  18. A Simple Vertical Slab Gel Electrophoresis Apparatus.

    ERIC Educational Resources Information Center

    Carter, J. B.; And Others

    1983-01-01

    Describes an inexpensive, easily constructed, and safe vertical slab gel kit used routinely for sodium dodecyl sulphate-polyacrylamide gel electrophoresis research and student experiments. Five kits are run from a single transformer. Because toxic solutions are used, students are given plastic gloves and closely supervised during laboratory…

  19. Chain Release Behavior of Gellan Gels

    NASA Astrophysics Data System (ADS)

    Hossain, Khandker S.; Nishinari, Katsuyoshi

    The chain release behavior from gellan gels was studied by immersing the gel into water and monitoring the mass loss as a function of time. Concentration of released gellan in the external solution was determined for gels of different sizes using phenol-sulfuric acid method. The chain release process became faster with increasing total surface area and volume. However the concentration of released chain normalized by surface area and volume suggests that the chain release itself is governed not only by the ionic effect and the amount of unassociated chains in gel but other factors such as osmotic pressure may play an important role on the chain release from the gels. The diffusion coefficient was estimated from the chain release process which is in the same order of magnitude reported for an isolated gellan chain by light scattering. Rheological measurements also suggest that the unassociated gellan chains are released out when immersed in pure water while unassociated chains are restricted to release out when immersed in salt solution due to the intrusion of cations which is responsible for further association of the unassociated gellan chains being in agreement with the previously published results. The elastic modulus of gels was increased by immersion of gels in water and in salt solutions, which can be attributed as the stiffening of network chains due to gel swelling and the conversion from free and unassociated chains into network chains, respectively, leading to an increase in elastic modulus with time.

  20. Sol-gel kinetics by NMR

    SciTech Connect

    Assink, R.A.; Kay, B.D.

    1991-01-01

    The chemical synthesis of advanced ceramic and glass materials by the sol-gel process has become an area of increasing activity in the field of material science. The sol-gel process provides a means to prepare homogeneous, high purity materials with tailored chemical and physical properties. This paper surveyed the nuclear magnetic resonance (NMR) studies of silicon-based sol-gel kinetics. A review of the various models which have been used to analyze the chemical kinetics of various sol-gel systems was presented. The utility of NMR spectroscopy was demonstrated in investigating the influence that various reaction conditions have on the reaction pathways by which sol-gel derived materials are synthesized. By observing in a direct fashion the chemical pathway of the sol-gel, it is often possible to relate the final properties of the material to the formulation and reaction conditions of the sol-gel. The study of reaction kinetics by NMR is expected to play an increasingly important role in understanding sol-gel processing and material properties. 15 refs. (DP)

  1. A Short-Duration Gel Diffusion Experiment.

    ERIC Educational Resources Information Center

    Mulcahy, D. E.

    1980-01-01

    Described is a gel diffusion experiment that permits the completion of duplicate diffusion runs within a three-hour laboratory session. Information included for the short-duration gel diffusion experiment is the diffusion cell, the experiment, data treatment, and the expected results of the experiment. (Author/DS)

  2. 21 CFR 866.4900 - Support gel.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Support gel. 866.4900 Section 866.4900 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents § 866.4900 Support gel....

  3. 21 CFR 866.4900 - Support gel.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Support gel. 866.4900 Section 866.4900 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents § 866.4900 Support gel....

  4. 21 CFR 866.4900 - Support gel.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Support gel. 866.4900 Section 866.4900 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents § 866.4900 Support gel....

  5. 21 CFR 866.4900 - Support gel.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Support gel. 866.4900 Section 866.4900 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents § 866.4900 Support gel....

  6. 21 CFR 866.4900 - Support gel.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Support gel. 866.4900 Section 866.4900 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents § 866.4900 Support gel....

  7. Fluorescence detection for gel and capillary electrophoresis

    SciTech Connect

    Hogan, B.

    1992-07-21

    First, an indirect fluorescence detection system for the separation of proteins via gel electrophoresis. Quantities as low as 50 nanograms of bovine serum albumin and soybean trypsin inhibitor are separated and detected visually without the need for staining of the analytes. This is very similar to levels of protein commonly separated with gel electrophoresis.

  8. To Grow, Nurture, and Maintain: Soil

    NASA Astrophysics Data System (ADS)

    Joshi, I.; Lam, K.; Hennelly, L. O.; Archie, J. P.

    2012-12-01

    The importance and difficulties encountered in a sustainable urban farm can be witnessed at the Stanford Earth Systems Educational Garden, in the growth, maintenance, and nurturing of the soil. Techniques and chemicals developed in the mid to late 1900's have infiltrated the traditional farming techniques that allowed humans to continuously farm for hundreds of years. The sudden spur of interest in sustainability has lead many, including Stanford Earth Systems, to reincorporate traditional methods in conjunction with modern technology. To override the damage made by chemicals and industrial farming, we had to recognize that healthy crops originated from healthy soil; thus we began investigating how to nourish soil. We began to research the ideal composition and structure of soil and methods to create and maintain fertile soil. Secondly, we prioritized the importance of nurturing plants and fed the plants with a plethora of natural fertilizers. We also created a compost pile so that the soil could rehabilitate and refill with nutrients with help provided by bacteria. Lastly, we had to maintain the soil to keep the soil viable for future crops. To do this, we had to acknowledge the chemical composition of the soil and plant cover crops to ensure that the nutrients are replenished. Our experiences enabled us to understand the time and effort required to manage suitable crops, animals, and structures for an urban farm.

  9. Maintaining Ancient Organelles: Mitochondrial Biogenesis and Maturation

    PubMed Central

    Vega, Rick B.; Horton, Julie L.; Kelly, Daniel P.

    2015-01-01

    The ultrastructure of the cardiac myocyte is remarkable for the high density of mitochondria tightly packed between sarcomeres. This structural organization is designed to provide energy in the form of ATP to fuel normal pump function of the heart. A complex system comprised of regulatory factors and energy metabolic machinery, encoded by both mitochondrial and nuclear genomes, is required for the coordinate control of cardiac mitochondrial biogenesis, maturation, and high-capacity function. This process involves the action of a transcriptional regulatory network that builds and maintains the mitochondrial genome, and to drive the expression of the energy transduction machinery. This finely tuned system is responsive to developmental and physiological cues as well as changes in fuel substrate availability. Deficiency of components critical for mitochondrial energy production frequently manifests as a cardiomyopathic phenotype, underscoring the requirement to maintain high respiration rates in the heart. Although a precise causative role is not clear, there is increasing evidence that perturbations in this regulatory system occur in the hypertrophied and failing heart. This review summarizes current knowledge and highlights recent advances in our understanding of the transcriptional regulatory factors and signaling networks that serve to regulate mitochondrial biogenesis and function in the mammalian heart. PMID:25999422

  10. Online maintaining appearance model using particle filter

    NASA Astrophysics Data System (ADS)

    Chen, Siying; Lan, Tian; Wang, Jianyu; Ni, Guoqiang

    2008-03-01

    Tracking by foreground matching heavily depends on the appearance model to establish object correspondences among frames and essentially, the appearance model should encode both the difference part between the object and background to guarantee the robustness and the stable part to ensure tracking consistency. This paper provides a solution for online maintaining appearance models by adjusting features in the model. Object appearance is co-modeled by a subset of Haar features selected from the over-complete feature dictionary which encodes the discriminative part of object appearance and the color histogram which describes the stable appearance. During the particle filtering process, feature values both from background patches and object observations are sampled efficiently by the aid of "foreground" and "background" particles respectively. Based on these sampled values, top-ranked discriminative features are added and invalid features are removed out to ensure the object being distinguishable from current background according to the evolving appearance model. The tracker based on this online appearance model maintaining technique has been tested on people and car tracking tasks and promising experimental results are obtained.

  11. Maintaining heterokaryosis in pseudo-homothallic fungi.

    PubMed

    Grognet, Pierre; Silar, Philippe

    2015-01-01

    Among all the strategies displayed by fungi to reproduce and propagate, some species have adopted a peculiar behavior called pseudo-homothallism. Pseudo-homothallic fungi are true heterothallics, i.e., they need 2 genetically-compatible partners to mate, but they produce self-fertile mycelium in which the 2 different nuclei carrying the compatible mating types are present. This lifestyle not only enables the fungus to reproduce without finding a compatible partner, but also to cross with any mate it may encounter. However, to be fully functional, pseudo-homothallism requires maintaining heterokaryosis at every stage of the life cycle. We recently showed that neither the structure of the mating-type locus nor hybrid-enhancing effect due to the presence of the 2 mating types accounts for the maintenance of heterokaryosis in the pseudo-homothallic fungus P. anserina. In this addendum, we summarize the mechanisms creating heterokaryosis in P. anserina and 2 other well-known pseudo-homothallic fungi, Neurospora tetrasperma and Agaricus bisporus. We also discuss mechanisms potentially involved in maintaining heterokaryosis in these 3 species. PMID:26479494

  12. Chewing Maintains Hippocampus-Dependent Cognitive Function

    PubMed Central

    Chen, Huayue; Iinuma, Mitsuo; Onozuka, Minoru; Kubo, Kin-Ya

    2015-01-01

    Mastication (chewing) is important not only for food intake, but also for preserving and promoting the general health. Recent studies have showed that mastication helps to maintain cognitive functions in the hippocampus, a central nervous system region vital for spatial memory and learning. The purpose of this paper is to review the recent progress of the association between mastication and the hippocampus-dependent cognitive function. There are multiple neural circuits connecting the masticatory organs and the hippocampus. Both animal and human studies indicated that cognitive functioning is influenced by mastication. Masticatory dysfunction is associated with the hippocampal morphological impairments and the hippocampus-dependent spatial memory deficits, especially in elderly. Mastication is an effective behavior for maintaining the hippocampus-dependent cognitive performance, which deteriorates with aging. Therefore, chewing may represent a useful approach in preserving and promoting the hippocampus-dependent cognitive function in older people. We also discussed several possible mechanisms involved in the interaction between mastication and the hippocampal neurogenesis and the future directions for this unique fascinating research. PMID:26078711

  13. Design guidelines for remotely maintainable equipment

    NASA Technical Reports Server (NTRS)

    Clarke, Margaret M.; Manouchehri, Davoud

    1988-01-01

    The quantity and complexity of on-orbit assets will increase significantly over the next decade. Maintaining and servicing these costly assets represent a difficult challenge. Three general methods are proposed to maintain equipment while it is still in orbit: an extravehicular activity (EVA) crew can perform the task in an unpressurized maintenance area outside any space vehicle; an intravehicular activity (IVA) crew can perform the maintenance in a shirt sleeve environment, perhaps at a special maintenance work station in a space vehicle; or a telerobotic manipulator can perform the maintenance in an unpressurized maintenance area at a distance from the crew (who may be EVA, IVA, or on the ground). However, crew EVA may not always be possible; the crew may have other demands on their time that take precedence. In addition, the orbit of the tasks themselves may be impossible for crew entry. Also crew IVA may not always be possible as option for equipment maintenance. For example, the equipment may be too large to fit through the vehicle airlock. Therefore, in some circumstances, the third option, telerobotic manipulation, may be the only feasible option. Telerobotic manipulation has, therefore, an important role for on-orbit maintenance. It is not only used for the reasons outlined above, but also used in some cases as backup to the EVA crew in an orbit that they can reach.

  14. Transparent poly(vinyl acetate)-silica gels by a sol-gel process

    NASA Astrophysics Data System (ADS)

    Wojcik, Anna B.; Klein, Lisa C.

    1993-12-01

    Rod shaped silica-poly(vinyl acetate) (PVAc) gels have been prepared by a sol gel process. In situ polymerization of tetraethoxysilane (TEOS) was accomplished in the presence of low molecular weight PVAc by dissolving various amounts of PVAc in a mixture of TEOS, ethanol, water and hydrochloric acid (HCl). Gelation of this mixture was carried out between room temperature and slightly above. Silica-PVAc rods recovered from cylindrical molds were homogeneous and transparent. Gels with weight percents of PVAc ranging from 2% to 50% were prepared. Silica-PVAc gels have higher flexure strengths, less brittle character and improved water durability in comparison with pure sol- gel silica.

  15. Thermotropic nanostructured "gel in gel" systems for improved oil recovery and water shutoff

    NASA Astrophysics Data System (ADS)

    Altunina, L. K.; Kuvshinov, V. A.; Stasyeva, L. A.

    2015-10-01

    Thermotropic nanostructured system with two gel-forming components has been created based on inorganic hydroxypolymer and organic polymer with a lower critical solution temperature of "aluminum salt-cellulose ether-carbamide-water", forming at heating a bound-dispersed nano-sized "gel in gel" structure. The studies on the kinetics of gelation and rheological properties of solutions and gels in this system have shown that the gels have a higher viscosity and elasticity and thereby are promising for creating deflecting screens in oil reservoirs, redistribution of filtration flows, improved oil recovery and for water shutoff.

  16. Drop spreading and resorbtion on gel surfaces

    NASA Astrophysics Data System (ADS)

    Banaha, Mehdi; Daerr, Adrian; Limat, Laurent

    2008-03-01

    We have studied the dynamics of liquid drops on agar gels, using a visualisation method which captures the evolution of the free surface. A first remarquable observation is that drops of water deposited on the surface do not spread, although the gel consists of up to 99.7% water and as low as 0.3% agarose. Instead, the drop slowly de-wets and resorbs into the gel which swells locally. If the deposited drop contains surfactants, the dynamics is very different. A sharp circular swelling front develops and progressively invades the whole surface. We study the propagation of this front as a function of surfactant and agarose concentration, and compare its typical properties to similar fronts appearing during mass swarming events of bacterial colonies under the same conditions. The observations reveal the complex nature of gel surface physico-chemistry and its aging, and may be related to recent friction measurements at gel interfaces.

  17. Photoswitchable gel assembly based on molecular recognition.

    PubMed

    Yamaguchi, Hiroyasu; Kobayashi, Yuichiro; Kobayashi, Ryosuke; Takashima, Yoshinori; Hashidzume, Akihito; Harada, Akira

    2012-01-01

    The formation of effective and precise linkages in bottom-up or top-down processes is important for the development of self-assembled materials. Self-assembly through molecular recognition events is a powerful tool for producing functionalized materials. Photoresponsive molecular recognition systems can permit the creation of photoregulated self-assembled macroscopic objects. Here we demonstrate that macroscopic gel assembly can be highly regulated through photoisomerization of an azobenzene moiety that interacts differently with two host molecules. A photoregulated gel assembly system is developed using polyacrylamide-based hydrogels functionalized with azobenzene (guest) or cyclodextrin (host) moieties. Reversible adhesion and dissociation of the host gel from the guest gel may be controlled by photoirradiation. The differential affinities of α-cyclodextrin or β-cyclodextrin for the trans-azobenzene and cis-azobenzene are employed in the construction of a photoswitchable gel assembly system. PMID:22215078

  18. Photoswitchable gel assembly based on molecular recognition

    PubMed Central

    Yamaguchi, Hiroyasu; Kobayashi, Yuichiro; Kobayashi, Ryosuke; Takashima, Yoshinori; Hashidzume, Akihito; Harada, Akira

    2012-01-01

    The formation of effective and precise linkages in bottom-up or top-down processes is important for the development of self-assembled materials. Self-assembly through molecular recognition events is a powerful tool for producing functionalized materials. Photoresponsive molecular recognition systems can permit the creation of photoregulated self-assembled macroscopic objects. Here we demonstrate that macroscopic gel assembly can be highly regulated through photoisomerization of an azobenzene moiety that interacts differently with two host molecules. A photoregulated gel assembly system is developed using polyacrylamide-based hydrogels functionalized with azobenzene (guest) or cyclodextrin (host) moieties. Reversible adhesion and dissociation of the host gel from the guest gel may be controlled by photoirradiation. The differential affinities of α-cyclodextrin or β-cyclodextrin for the trans-azobenzene and cis-azobenzene are employed in the construction of a photoswitchable gel assembly system. PMID:22215078

  19. Improving immobilized biocatalysts by gel phase polymerization

    SciTech Connect

    Kuu, W.Y.; Polack, J.A.

    1983-08-01

    A new method is presented for the treatment of gel-type supports, used for immobilizing microbial cells and enzymes, to obtain high mechanical strength. It is particularly useful for ethanol fermentation over gel beads containing immobilized viable cells, where the beads can be ruptured by gas production and the growth of cells within the gels. This method consists of treating agar or carrageenan gel with polyacrylamide to form a rigid support which retains the high catalytic activity characteristic of the untreated biocatalysts. The size and shape of the biocatalyst is unaffected by this treatment. The method involves the diffusion of acrylamide, N,N'-methylenebisacrylamide and BETA-dimethylaminopropionitrile (or N,N,N',N'-tetramethylethylenediamine) into the preformed biocatalyst beads followed by the addition of an initiator to cause polymerization within the beads. Treated gels have been used for the continuous fermentation of glucose to ethanol in a packed column for over two months.

  20. Generation of inkjet drop of particulate gel

    NASA Astrophysics Data System (ADS)

    Yoo, Hansol; Kim, Chongyoup

    2015-08-01

    The generation of inkjet drops of colloidal gels is studied experimentally. Particle suspensions are prepared by dispersing spherical polystyrene particles of 620 nm in the 1:1 mixture of deionized water and ethylene glycol. The gels are prepared by adding polyethylene oxide to the suspensions by inducing the depletion interaction between particles. It is demonstrated that inkjet drops can be generated by using the colloidal gels. It is found that the ligament extended from the inkjet nozzle is stabilized so that the drop can be generated without satellite droplets behind the main drop and the velocity of the gel drop is faster than that of the polymer solution at the same concentration. The gel drop generation characteristics are found to be sensitive to input voltage.

  1. Radiological properties of normoxic polymer gel dosimeters

    SciTech Connect

    Venning, A.J.; Nitschke, K.N.; Keall, P.J.; Baldock, C.

    2005-04-01

    The radiological properties of the normoxic polymer gel dosimeters MAGIC, MAGAS, and MAGAT [methacrylic and ascorbic acid in gelatin initiated by copper; methacrylic acid gelatine gel with ascorbic acid; and methacrylic acid gelatine and tetrakis (hydroxymethyl) phosphonium chloride, respectively] have been investigated. The radiological water equivalence was determined by comparing the polymer gel macroscopic photon and electron interaction cross sections over the energy range from 10 keV to 20 MeV and by Monte Carlo modeling of depth doses. Normoxic polymer gel dosimeters have a high gelatine and monomer concentration and therefore mass density (kg m{sup -3}) up to 3.8% higher than water. This results in differences between the cross-section ratios of the normoxic polymer gels and water of up to 3% for the attenuation, energy absorption, and collision stopping power coefficient ratios through the Compton dominant energy range. The mass cross-section ratios were within 2% of water except for the mass attenuation and energy absorption coefficients ratios, which showed differences with water of up to 6% for energies less than 100 keV. Monte Carlo modeling was undertaken for the polymer gel dosimeters to model the electron and photon transport resulting from a 6 MV photon beam. The absolute percentage differences between gel and water were within 1% and the relative percentage differences were within 3.5%. The results show that the MAGAT gel formulation is the most radiological water equivalent of the normoxic polymer gel dosimeters investigated due to its lower mass density measurement compared with MAGAS and MAGIC gels.

  2. Dewatering fine coal slurries by gel extraction

    SciTech Connect

    Gehrke, S.H.; Lyu, Lii-Hurng.

    1990-01-01

    A new technology called gel extraction has been evaluated to determine its economic viability in dewatering the fine and ultrafine coal slurries generated upon separation of sulfur and ash from clean coal during the physical coal cleaning process. Water must be removed from such slurries prior to transportation and combustion but the dewatering costs are substantial, especially for the fine particles below 28 mesh (0.6 mm). Gel extraction is a potential breakthrough in slurry dewatering technology. The goal of this project was to acquire the qualitative and quantitative data needed to estimate the potential of gel extraction for dewatering coal slurries. The specific objectives were to determine the maximum extents of dewatering (minimum surface moisture in the coal product), the clarity of the water removed (minimum solids content), the speed of the dewatering cycles, the service lifetime of the gels, and the factors which influence all of these. With the results obtained, an economic analysis of Ohio coal cleaning plant dewatering technologies was carried out. The polymer gel at the heart of this project, poly (N-isopropylacrylamide) (PNIPA), can swell several times its shrunken weight at 32[degrees]C by absorbing water at 25[degrees]C. In gel extraction, a shrunken NIPA gel is contacted with a slurry at ambient temperature or cooler; the gel swells by absorbing water from the slurry. The gel is then removed from the dewatered slurry and warmed above its critical temperature of 33[degrees]C, which returns it to the shrunken state by releasing the absorbed water. The facts that the gel is reusable and the process is simple and driven by low-grade energy (warm temperatures), and not inherently limited by particle size, made the process an attractive possible alternative to centrifugation, screening, filtration, etc. for slurry dewatering.

  3. Sol–gel composite material characteristics caused by different dielectric constant sol–gel phases

    NASA Astrophysics Data System (ADS)

    Kimoto, Keisuke; Matsumoto, Makoto; Kaneko, Tsukasa; Kobayashi, Makiko

    2016-07-01

    Ultrasonic transducers prepared by a sol–gel composite method have been investigated in the field of nondestructive testing (NDT). Sol–gel composite materials could be ideal piezoelectric materials for ultrasonic transducer applications in the NDT field, and a new sol–gel composite with desirable characteristics has been developed. Three kinds of sol–gel composite materials composed of different dielectric constant sol–gel phases, Pb(Zr,Ti)O3 (PZT), Bi4Ti3O12 (BiT), and BaTiO3 (BT), and the same piezoelectric powder phase, PbTiO3 (PT), were fabricated and their properties were compared quantitatively. As a result, the PT/BT, sol–gel composite with the highest dielectric constant sol–gel phase showed the highest d 33 and signal strength. In addition, only PT/BT was successfully poled by room-temperature corona poling with reasonable signal strength.

  4. Moisture Transport in Silica Gel Particle Beds: I. Theoretical Study

    SciTech Connect

    Pesaran, A. A.; Mills, A. F.

    1986-08-01

    Diffusion mechanisms of moisture within silica gel particles are investigated. It is found that for microporous silica gel surface diffusion is the dominant mechanism of moisture transport, while for macroporous silica gel both Knudsen and surface diffusion are important.

  5. Heartwarming memories: Nostalgia maintains physiological comfort.

    PubMed

    Zhou, Xinyue; Wildschut, Tim; Sedikides, Constantine; Chen, Xiaoxi; Vingerhoets, Ad J J M

    2012-08-01

    Nostalgia, a sentimental longing or wistful affection for the past, is a predominantly positive and social emotion. Recent evidence suggests that nostalgia maintains psychological comfort. Here, we propose, and document in five methodologically diverse studies, a broader homeostatic function for nostalgia that also encompasses the maintenance of physiological comfort. We show that nostalgia--an emotion with a strong connotation of warmth--is triggered by coldness. Participants reported stronger nostalgia on colder (vs. warmer) days and in a cold (vs. neutral or warm) room. Nostalgia, in turn, modulates the interoceptive feeling of temperature. Higher levels of music-evoked nostalgia predicted increased physical warmth, and participants who recalled a nostalgic (vs. ordinary autobiographical) event perceived ambient temperature as higher. Finally, and consistent with the close central nervous system integration of temperature and pain sensations, participants who recalled a nostalgic (vs. ordinary autobiographical) event evinced greater tolerance to noxious cold. PMID:22390713

  6. Maintaining human productivity during Mars transit

    NASA Technical Reports Server (NTRS)

    Statler, Irving C.; Billings, Charles E.

    1989-01-01

    This paper addresses the special nature of the human-machine relationship during a trip to Mars. In particular, the potential for monotony and boredom during a long-duration space voyage and the effect on motivation and productivity can be important considerations to the health and welfare of the crew. For the voyage to Mars, a design may be considered that will purposefully maintain some level of workload for the crew as a preventive measure for the deterioration of productivity that comes with boredom. This paper speculates on these considerations, on the appropriate level of workload for maximum productivity, and on what might be done during the mission to alleviate the problems caused by monotony and boredom.

  7. Maintained generalization of delay-specific remembering.

    PubMed

    White, K Geoffrey; Sargisson, Rebecca J

    2011-07-01

    According to the discrimination hypothesis (White, 2002), remembering is a delay-specific discrimination made at the time of retrieval. In the present experiment the delay-specific nature of the discrimination was made explicit by making correct choices in a delayed matching-to-sample task performed by pigeons conditional on whether the retention interval was short or long. Retention interval was varied over several durations in a maintained generalization test without reinforcement for correct matching responses. Opposing gradients demonstrated generalization of delay-specific remembering, consistent with the view that the temporal dimension of the retention interval can be treated in the same way as non-temporal dimensions of the sample stimulus. PMID:21704683

  8. Peru struggles to maintain crude production

    SciTech Connect

    Not Available

    1991-01-14

    Revival of Peru's moribund oil and gas industry in the 1990s hinges on whether the new administration of President Alberto Fujimori is successful in attracting foreign investment in Peru. Fujimori's success would mean Peru pushing ahead into stepped up exploration and major development projects, such as the huge Camisea gas/condensate field discovered 2 years ago. His failure could mean Peru continuing to fall further behind in its already lagging low oil production. Huge sums of money will be needed. Peru also needs to succeed in its efforts to become creditworthy again for international agencies, foreign governments, and commercial banks. Meanwhile, Petroleos del Peru SA (Petroperu), the state oil company, will have to transfer an increasing share of its operations to private investors. But the company is likely to try to hold onto producing fields, even though it is unable to maintain full output.

  9. Implementing and maintaining an infusion alliance.

    PubMed

    Meyer, Britt M

    2010-01-01

    Infusion therapy models are ever changing and growing in modern health care. New technologies and problems arise daily as researchers and clinicians explore our world. As technologies advance, health care costs are also skyrocketing. The vast majority of hospitalized patients will receive some form of infusion therapy during their stay, and many will continue to receive therapy after they are discharged from the inpatient setting. Infusion alliances can aid cost containment by decreasing infusion-related complication rates, affect customer satisfaction, and promote interdisciplinary collaboration. This article discusses the potential benefits of an infusion alliance, details steps for using the performance improvement process when implementing and maintaining an alliance, and outlines the components of a successful business plan. PMID:20841983

  10. Maintaining robust connectivity in heterogeneous robotic networks

    NASA Astrophysics Data System (ADS)

    Cruz, P.; Fierro, R.; Lu, W.; Ferrari, S.

    2013-05-01

    In this paper, we are interested in exploiting the heterogeneity of a robotic network made of ground and aerial agents to sense multiple targets in a cluttered environment. Maintaining wireless communication on this type of networks is fundamentally important specially for cooperative purposes. The proposed heterogeneous network consists of ground sensors, e.g., OctoRoACHes, and aerial routers, e.g., quadrotors. Adaptive potential field methods are used to coordinate the ground mobile sensors. Moreover, a reward function for the aerial mobile wireless routers is formulated to guarantee communication coverage among the ground sensors and a fixed base station. A sub-optimal controller is proposed based on an approximate control policy iteration technique. Simulation results of a case study are presented to illustrate the proposed methodology.

  11. [Maintaining solidarity: is mutuality the solution?].

    PubMed

    Gevers, J K M; Ploem, M C

    2013-01-01

    Solidarity is essentially the willingness to contribute to the community and its demands, which may even involve contributing more than one is expecting to receive. Another principle is mutuality: this refers to a balance between rights and obligations or between mutual obligations. In its advisory document 'The importance of mutuality......solidarity takes work!', The Dutch Council for Public Health and Health Care underlines the importance of ensuring solidarity within the Dutch health care system, e.g. by encouraging patients to take responsibility for their own health, possibly by introducing elements of mutuality. In our contribution, we comment on the Council's advice. Although we fully agree with the overall conclusion that solidarity should be maintained within the system, we do not see how the introduction of increased mutuality will contribute to this goal. PMID:23945438

  12. Maintaining technical excellence requires a national plan

    NASA Technical Reports Server (NTRS)

    Davidson, T. F.

    1991-01-01

    To meet the challenge of technical excellence, AIA established a rocket propulsion committee to develop the National Rocket Propulsion Strategic Plan. Developing such a plan required a broad spectrum of experience and disciplines. The Strategic Plan team needed the participation of industry, government, and academia. The plan provides, if followed, a means for the U.S. to maintain technical excellence and world leadership in rocket propulsion. To implement the National Rocket Propulsion Strategic Plan is to invest in the social, economic, and technological futures of America. The plan lays the basis for upgrading existing propulsion systems and a firm base for future full scale development, production, and operation of rocket propulsion systems for space, defense, and commercial applications.

  13. Opportunities for improving the performance of LCV micelle gel dosimeters: II. Recipe optimization

    NASA Astrophysics Data System (ADS)

    Nasr, A. T.; Alexander, K. M.; Olding, T.; Schreiner, L. J.; McAuley, K. B.

    2015-01-01

    Designed experiments and empirical models are used to optimize a Leuco Crystal Violet (LCV) micelle gel recipe to improve dose sensitivity and initial colour. The optimized recipe contains 0.75 mM LCV, 17.0 mM Cetyl Trimethyl Ammonium Bromide (CTAB), 120 mM 2,2,2-trichloroethanol (TCE), 25.0 mM tri-chloro acetic acid (TCAA), 4 wt% gelatin and ~96 wt% water. Dose sensitivity of the optimized gel is 1.5 times higher than Jordan's standard LCV gel. Spatial integrity of the 3D dose distribution information in 1L jar phantoms made using this recipe is maintained for more than two weeks.

  14. Highly stretchable carbon nanotube transistors enabled by buckled ion gel gate dielectrics

    SciTech Connect

    Wu, Meng-Yin; Chang, Tzu-Hsuan; Ma, Zhenqiang; Zhao, Juan; Xu, Feng; Jacobberger, Robert M.; Arnold, Michael S.

    2015-08-03

    Deformable field-effect transistors (FETs) are expected to facilitate new technologies like stretchable displays, conformal devices, and electronic skins. We previously demonstrated stretchable FETs based on buckled thin films of polyfluorene-wrapped semiconducting single-walled carbon nanotubes as the channel, buckled metal films as electrodes, and unbuckled flexible ion gel films as the dielectric. The FETs were stretchable up to 50% without appreciable degradation in performance before failure of the ion gel film. Here, we show that by buckling the ion gel, the integrity and performance of the nanotube FETs are extended to nearly 90% elongation, limited by the stretchability of the elastomer substrate. The FETs maintain an on/off ratio of >10{sup 4} and a field-effect mobility of 5 cm{sup 2} V{sup −1} s{sup −1} under elongation and demonstrate invariant performance over 1000 stretching cycles.

  15. Use of Aloe vera gel coating preserves the functional properties of table grapes.

    PubMed

    Serrano, María; Valverde, Juan Miguel; Guillén, Fabian; Castillo, Salvador; Martínez-Romero, Domingo; Valero, Daniel

    2006-05-31

    Table grapes (Vitis vinifera L. cv. Crimson Seedless) were coated with Aloe vera gel according to our developed patent (SP Patent P200302937) and then stored for 35 days at 1 degrees C, and the subsequent shelf life (SL) was monitored at 20 degrees C. Uncoated clusters showed a rapid loss of functional compounds, such as total phenolics and ascorbic acid. These changes were accompanied by reduction of the total antioxidant activity (TAA) and increases in total anthocyanins, showing an accelerated ripening process. On the contrary, table grapes coated with Aloe vera gel significantly delayed the above changes, such as the retention of ascorbic acid during cold storage or SL. Consequently, Aloe vera gel coating, a simple and noncontaminating treatment, maintained the functional properties during postharvest storage of table grapes. PMID:16719510

  16. Sol-Gel Manufactured Energetic Materials

    DOEpatents

    Simpson, Randall L.; Lee, Ronald S.; Tillotson, Thomas M.; Hrubesh, Lawrence W.; Swansiger, Rosalind W.; Fox, Glenn A.

    2005-05-17

    Sol-gel chemistry is used for the preparation of energetic materials (explosives, propellants and pyrotechnics) with improved homogeneity, and/or which can be cast to near-net shape, and/or made into precision molding powders. The sol-gel method is a synthetic chemical process where reactive monomers are mixed into a solution, polymerization occurs leading to a highly cross-linked three dimensional solid network resulting in a gel. The energetic materials can be incorporated during the formation of the solution or during the gel stage of the process. The composition, pore, and primary particle sizes, gel time, surface areas, and density may be tailored and controlled by the solution chemistry. The gel is then dried using supercritical extraction to produce a highly porous low density aerogel or by controlled slow evaporation to produce a xerogel. Applying stress during the extraction phase can result in high density materials. Thus, the sol-gel method can be used for precision detonator explosive manufacturing as well as producing precision explosives, propellants, and pyrotechnics, along with high power composite energetic materials.

  17. Sol-gel manufactured energetic materials

    DOEpatents

    Simpson, Randall L.; Lee, Ronald S.; Tillotson, Thomas M.; Hrubesh, Lawrence W.; Swansiger, Rosalind W.; Fox, Glenn A.

    2003-12-23

    Sol-gel chemistry is used for the preparation of energetic materials (explosives, propellants and pyrotechnics) with improved homogeneity, and/or which can be cast to near-net shape, and/or made into precision molding powders. The sol-gel method is a synthetic chemical process where reactive monomers are mixed into a solution, polymerization occurs leading to a highly cross-linked three dimensional solid network resulting in a gel. The energetic materials can be incorporated during the formation of the solution or during the gel stage of the process. The composition, pore, and primary particle sizes, gel time, surface areas, and density may be tailored and controlled by the solution chemistry. The gel is then dried using supercritical extraction to produce a highly porous low density aerogel or by controlled slow evaporation to produce a xerogel. Applying stress during the extraction phase can result in high density materials. Thus, the sol-gel method can be used for precision detonator explosive manufacturing as well as producing precision explosives, propellants, and pyrotechnics, along with high power composite energetic materials.

  18. Electroacoustics of Particles Dispersed in Polymer Gel

    SciTech Connect

    Bhosale, Prasad S.; Chun, Jaehun; Berg, John C.

    2011-06-27

    This study examines the acoustic electrophoresis of particles dispersed in polymer hydrogels, with the particle size either less than or greater than the gel mesh size. When the particles are smaller than the gel mesh size, their acoustic vibration is resisted by only the background water medium, and the measured dynamic electrophoretic mobility, μd (obtained in terms of colloid vibration current, CVI), is the same as in water. For the case of particles larger than the gel mesh size, μd is decreased due to trapping, and the net decrease depends on the viscoelastic properties of the gel. The gel mesh size was varied by varying its crosslink density, the latter being characterized as the storage modulus, G’. The dependence of mobility on G’, for systems of a given particle size, and on particle size, for gels of a given G’, are investigated. The measured mobility remains constant as G’ is increased (i.e., mesh size is decreased) up to a value of approximately 300 Pa, beyond which it decreases. In the second set of measurements, the trapped particle size was increased in a gel medium of constant mesh size, with G’ approximately 100 Pa. In this case, the measured μd is found to be effectively constant over the particle size range studied (14-120 nm), i.e., it is independent of the degree of trapping as expressed by the ratio of the particle size to the mesh size.

  19. Light-activated, in situ forming gel for sustained suprachoroidal delivery of bevacizumab.

    PubMed

    Tyagi, Puneet; Barros, Matthew; Stansbury, Jeffrey W; Kompella, Uday B

    2013-08-01

    A light-activated polycaprolactone dimethacrylate (PCM) and hydroxyethyl methacrylate (HEMA) based gel network was developed to sustain the release of stable, active bevacizumab (an anti-VEGF antibody used to treat choroidal neovascularization) and used to assess sustained ex vivo delivery in rabbit eyes and in vivo delivery in rat eyes following in situ gel formation in the suprachoroidal space. PCM was synthesized from polycaprolactone diol (PCD) and evaluated using NMR spectroscopy. PCM was used to cross-link HEMA in the presence of 365 nm UV light and 2,2-dimethoxy-2-phenylacetophenone (DMPA) as a photoinitiator. Bevacizumab was entrapped in the gel using three different cross-linking durations of 3, 7, and 10 min. In vitro release of bevacizumab in PBS pH 7.4 at 37 °C during a 4 month study was quantified using a VEGF-binding based ELISA. The stability of released bevacizumab was monitored by size exclusion chromatography (SEC) and circular dichroism. Alexa Fluor 488 dye conjugated bevacizumab mixed with polymers was injected suprachoroidally in rabbit eyes to study the effect of different cross-linking durations on the spread of the dye conjugated bevacizumab. In vivo delivery was assessed in Sprague-Dawley (SD) rats by injecting Alexa Fluor 488 dye conjugated bevacizumab mixed with polymers followed by cross-linking for 10 min. Spread in the rabbit eyes and in vivo delivery in rat eyes was monitored noninvasively using a fundus camera and Fluorotron Master. The formation of PCM was confirmed by the disappearance of hydroxyl peak in NMR spectra. A cross-linking duration of 10 min resulted in a burst release of 21% of bevacizumab. Other cross-linking durations had ≥62% burst release. Bevacizumab release from 10 min cross-linked gel was sustained for ∼4 months. Release samples contained ≥96.1% of bevacizumab in the monomeric form as observed in SEC chromatograms. Circular dichroism confirmed that secondary β-sheet structure of bevacizumab was maintained

  20. Evaluation of radiochromic gel dosimetry and polymer gel dosimetry in a clinical dose verification

    NASA Astrophysics Data System (ADS)

    Vandecasteele, Jan; De Deene, Yves

    2013-09-01

    A quantitative comparison of two full three-dimensional (3D) gel dosimetry techniques was assessed in a clinical setting: radiochromic gel dosimetry with an in-house developed optical laser CT scanner and polymer gel dosimetry with magnetic resonance imaging (MRI). To benchmark both gel dosimeters, they were exposed to a 6 MV photon beam and the depth dose was compared against a diamond detector measurement that served as golden standard. Both gel dosimeters were found accurate within 4% accuracy. In the 3D dose matrix of the radiochromic gel, hotspot dose deviations up to 8% were observed which are attributed to the fabrication procedure. The polymer gel readout was shown to be sensitive to B0 field and B1 field non-uniformities as well as temperature variations during scanning. The performance of the two gel dosimeters was also evaluated for a brain tumour IMRT treatment. Both gel measured dose distributions were compared against treatment planning system predicted dose maps which were validated independently with ion chamber measurements and portal dosimetry. In the radiochromic gel measurement, two sources of deviations could be identified. Firstly, the dose in a cluster of voxels near the edge of the phantom deviated from the planned dose. Secondly, the presence of dose hotspots in the order of 10% related to inhomogeneities in the gel limit the clinical acceptance of this dosimetry technique. Based on the results of the micelle gel dosimeter prototype presented here, chemical optimization will be subject of future work. Polymer gel dosimetry is capable of measuring the absolute dose in the whole 3D volume within 5% accuracy. A temperature stabilization technique is incorporated to increase the accuracy during short measurements, however keeping the temperature stable during long measurement times in both calibration phantoms and the volumetric phantom is more challenging. The sensitivity of MRI readout to minimal temperature fluctuations is demonstrated which

  1. Normoxic polymer gels: are they magic?

    NASA Astrophysics Data System (ADS)

    Amin, M. N.; Bonnett, D. E.; Horsfield, M. A.

    2004-01-01

    In the last few years there has been considerable interest in the use of polymer gels to measure complex dose distributions in radiotherapy. Despite considerable advantages they are still not widely used in clinical situations. This is due primarily to the difficulty in manufacture, particularly the need to exclude oxygen both from the gel and the manufacturing process, the limited number of suitable phantom materials and the need for easy access to an MRI facility. The purpose of this paper is to report on an investigation of the basic properties of MAGIC gels namely: linearity of response, effects of temperature and stability.

  2. Phantom for moving organ dosimetry with gel

    NASA Astrophysics Data System (ADS)

    Ravindran, Paul; Mahata, Anurupa; Suman Babu, Ebenezer

    2009-05-01

    The displacements caused by the cardiac and respiratory motions cause smearing of the dose distribution that defeats the purpose of high precision radiotherapy. A phontom that holds a gel cylinder and radiochromic film, was designed and developed to simulate the respiratory motion in the superior and inferior directions. The effect of lung movement on dose distribution was studied by exposing gel as well as a radiochromic film using the phantom. The results obtained with Gel was comparable to those obtained with the radiochromic films.

  3. Communicating contentious geoscience issues and maintaining impartiality

    NASA Astrophysics Data System (ADS)

    Nice, S. E.; Mitchell, C.

    2013-12-01

    Shale Gas exploration in the UK has been major and often controversial news in the British media over the last 2 years. The British Geological Survey (BGS) has been an integral part of this story as the UK Governments independent and impartial advisor on geosciences. BGS has been involved in writing policy on fracking and induced earthquakes as well as researching potential quantities of shale gas in the UK and also researching natural methane levels in groundwater before large scale fracking activities begin. Shale Gas in the UK, as in the US and Europe has caused much controversy and as a result has many pro and anti fracking campaigns. The challenge for BGS has been to deliver front line science, whilst maintaining complete impartiality on the subject. The BGS communications team developed a strategy over this period to ensure that our message was clear and strong. This involved working closely with the scientists involved to formulate key messages that could delivered through controlled statements on the BGS webpages, press releases, at press conferences as well as on broadcast and print media. Our scientists were media trained during this time to ensure that they stayed en message and wouldn't be caught by the press or opponents of fracking into making statements that could have been used to either scare up the position or give the antagonist room to cast doubt on our impartiality. This strategy proved highly successful and BGS managed to communicate the facts, remain impartial whilst avoiding attempts to undermine the potential for Shale gas exploitation in the UK. The success of this communication strategy was due to the cooperation of the scientists, a clear strategy from the communications team and the unequivocal support of the senior executive at BGS. This abstract will conclude how the BGS has developed its communication strategy to be more streamlined and open. BGS must allow it's scientists to talk to the media about the science that they do. Much of

  4. Endotracheal intubation using i-gel® and lightwand in a patient with difficult airway: a case report

    PubMed Central

    Choi, Chun Gil; Yang, Ki-Hwan; Jung, Jong-Kwon; Han, Jeong Uk; Lee, Choon Soo; Cha, Young-Deog

    2015-01-01

    This case report involves tracheal intubation using i-gel® in combination with a lightwand in a patient with a difficult airway, classified as Cormack-Lehane grade 3. I-gel® was used during anesthesia induction to properly maintain ventilation. The authors have previously reported successful tracheal intubation on a patient with a difficult airway through the use of i-gel® and a fiberoptic bronchoscope. However, if the use of a fiberoptic bronchoscope is not immediately available in a patient with a difficult airway, tracheal intubation may be performed by using i-gel® and a lightwand in a patient with difficult airway, allowing the safe induction of anesthesia. PMID:26495062

  5. Virus Movement Maintains Local Virus Population Diversity

    SciTech Connect

    J. Snyder; B. Wiedenheft; M. Lavin; F. Roberto; J. Spuhler; A. Ortmann; T. Douglas; M. Young

    2007-11-01

    Viruses are the largest reservoir of genetic material on the planet, yet little is known about the population dynamics of any virus within its natural environment. Over a 2-year period, we monitored the diversity of two archaeal viruses found in hot springs within Yellowstone National Park (YNP). Both temporal phylogeny and neutral biodiversity models reveal that virus diversity in these local environments is not being maintained by mutation but rather by high rates of immigration from a globally distributed metacommunity. These results indicate that geographically isolated hot springs are readily able to exchange viruses. The importance of virus movement is supported by the detection of virus particles in air samples collected over YNP hot springs and by their detection in metacommunity sequencing projects conducted in the Sargasso Sea. Rapid rates of virus movement are not expected to be unique to these archaeal viruses but rather a common feature among virus metacommunities. The finding that virus immigration rather than mutation can dominate community structure has significant implications for understanding virus circulation and the role that viruses play in ecology and evolution by providing a reservoir of mobile genetic material.

  6. Exploring how nurse lecturers maintain clinical credibility.

    PubMed

    Fisher, Melanie T

    2005-01-01

    The role of the nurse lecturer is changing. There is growing pressure from the government and professionals alike to recruit nurse teachers who posses both practical and recent experience of nursing [Department of Health, 1999. Making a Difference: Strengthening the Nursing, Midwifery and Health Visiting Contribution to Health and Health Care. DOH, London; UKCC, 2000. Standards for the Preparation of Teachers of Nursing, Midwifery and Health Visiting. UKCC, London]. Whilst much of the literature available suggests a growing concern amongst practitioners, students and nurse educationalists themselves about the importance of being ;clinically credible', what is not clear is how tangible it is to maintain currency and clinical credibility. In addition, the term ;clinical credibility' is in itself ill-defined. An exploratory study was undertaken within one higher education institution which sought to seek the views of nurse lecturers. The principles of ethnography were applied to this research. The sample included six of the most recently appointed nurse lecturers within one academic faculty who taught predominantly on pre-registration programmes. Data from individual and focus group interviews was analysed using a thematic content analysis approach. The findings are discussed which embrace the concepts of: working ;hands on' in the clinical area, clinical currency, transferability of skills, clinical visibility and role development. Recommendations for the development of professional practice are offered. PMID:19038175

  7. Achieving and maintaining cognitive vitality with aging.

    PubMed

    Fillit, Howard M; Butler, Robert N; O'Connell, Alan W; Albert, Marilyn S; Birren, James E; Cotman, Carl W; Greenough, William T; Gold, Paul E; Kramer, Arthur F; Kuller, Lewis H; Perls, Thomas T; Sahagan, Barbara G; Tully, Tim

    2002-07-01

    Cognitive vitality is essential to quality of life and survival in old age. With normal aging, cognitive changes such as slowed speed of processing are common, but there is substantial interindividual variability, and cognitive decline is clearly not inevitable. In this review, we focus on recent research investigating the association of various lifestyle factors and medical comorbidities with cognitive aging. Most of these factors are potentially modifiable or manageable, and some are protective. For example, animal and human studies suggest that lifelong learning, mental and physical exercise, continuing social engagement, stress reduction, and proper nutrition may be important factors in promoting cognitive vitality in aging. Manageable medical comorbidities, such as diabetes, hypertension, and hyperlipidemia, also contribute to cognitive decline in older persons. Other comorbidities such as smoking and excess alcohol intake may contribute to cognitive decline, and avoiding these activities may promote cognitive vitality in aging. Various therapeutics, including cognitive enhancers and protective agents such as antioxidants and anti-inflammatories, may eventually prove useful as adjuncts for the prevention and treatment of cognitive decline with aging. The data presented in this review should interest physicians who provide preventive care management to middle-aged and older individuals who seek to maintain cognitive vitality with aging. PMID:12108606

  8. Support activities to maintain SUMS flight readiness

    NASA Technical Reports Server (NTRS)

    Wright, Willie

    1992-01-01

    The Shuttle Upper Atmosphere Mass Spectrometer (SUMS), a component experiment of the NASA Orbital Experiments Program (OEX), was flown aboard the shuttle Columbia (OV102) mounted at the forward end of the nose landing gear well with an atmospheric gas inlet system fitted to the lower fuselage (chin panel) surface. The SUMS was designed to provide atmospheric data in flow regimes inaccessible prior to the development of the Space Transportation System (STS). The experiment mission operation began about one hour prior to shuttle de-orbit entry maneuver and continued until reaching 1.6 torr (about 86 km altitude). The SUMS mass spectrometer consists of the spare unit from the Viking mission to Mars. Bendix Aerospace under contract to NASA LaRC incorporated the Viking mass spectrometer, a microprocessor based logic card, a pressurized instrument case, and the University of Texas at Dallas provided a gas inlet system into a configuration suited to interface with the shuttle Columbia. The SUMS experiment underwent static and dynamic calibration as well as vacuum maintenance before and after STS 40 shuttle flight. The SUMS flew a total of 3 times on the space shuttle Columbia. Between flights the SUMS was maintained in flight ready status. The flight data has been analyzed by the NASA LaRC Aerothermodynamics Branch. Flight data spectrum plots and reports are presented in the Appendices to the Final Technical Report for NAS1-17399.

  9. MAVS maintains mitochondrial homeostasis via autophagy

    PubMed Central

    Sun, Xiaofeng; Sun, Liwei; Zhao, Yuanyuan; Li, Ying; Lin, Wei; Chen, Dahua; Sun, Qinmiao

    2016-01-01

    Mitochondrial antiviral signalling protein (MAVS) acts as a critical adaptor protein to transduce antiviral signalling by physically interacting with activated RIG-I and MDA5 receptors. MAVS executes its functions at the outer membrane of mitochondria to regulate downstream antiviral signalling, indicating that the mitochondria provides a functional platform for innate antiviral signalling transduction. However, little is known about whether and how MAVS-mediated antiviral signalling contributes to mitochondrial homeostasis. Here we show that the activation of MAVS is sufficient to induce autophagic signalling, which may mediate the turnover of the damaged mitochondria. Importantly, we find MAVS directly interacts with LC3 through its LC3-binding motif ‘YxxI’, suggesting that MAVS might act as an autophagy receptor to mediate mitochondrial turnover upon excessive activation of RLR signalling. Furthermore, we provide evidence that both MAVS self-aggregation and its interaction with TRAF2/6 proteins are important for MAVS-mediated mitochondrial turnover. Collectively, our findings suggest that MAVS acts as a potential receptor for mitochondria-associated autophagic signalling to maintain mitochondrial homeostasis. PMID:27551434

  10. CDC20 maintains tumor initiating cells

    PubMed Central

    Xie, Qi; Wu, Qiulian; Mack, Stephen C.; Yang, Kailin; Kim, Leo; Hubert, Christopher G.; Flavahan, William A.; Chu, Chengwei; Bao, Shideng; Rich, Jeremy N.

    2015-01-01

    Glioblastoma is the most prevalent and lethal primary intrinsic brain tumor. Glioblastoma displays hierarchical arrangement with a population of self-renewing and tumorigenic glioma tumor initiating cells (TICs), or cancer stem cells. While non-neoplastic neural stem cells are generally quiescent, glioblastoma TICs are often proliferative with mitotic control offering a potential point of fragility. Here, we interrogate the role of cell-division cycle protein 20 (CDC20), an essential activator of anaphase-promoting complex (APC) E3 ubiquitination ligase, in the maintenance of TICs. By chromatin analysis and immunoblotting, CDC20 was preferentially expressed in TICs relative to matched non-TICs. Targeting CDC20 expression by RNA interference attenuated TIC proliferation, self-renewal and in vivo tumor growth. CDC20 disruption mediated its effects through induction of apoptosis and inhibition of cell cycle progression. CDC20 maintains TICs through degradation of p21CIP1/WAF1, a critical negative regulator of TICs. Inhibiting CDC20 stabilized p21CIP1/WAF1, resulting in repression of several genes critical to tumor growth and survival, including CDC25C, c-Myc and Survivin. Transcriptional control of CDC20 is mediated by FOXM1, a central transcription factor in TICs. These results suggest CDC20 is a critical regulator of TIC proliferation and survival, linking two key TIC nodes – FOXM1 and p21CIP1/WAF1 — elucidating a potential point for therapeutic intervention. PMID:25938542

  11. Two retrotransposons maintain telomeres in Drosophila

    PubMed Central

    Pardue, M.-L.; Rashkova, S.; Casacuberta, E.; DeBaryshe, P.G.; George, J. A.; Traverse, K.L.

    2005-01-01

    Telomeres across the genus Drosophila are maintained, not by telomerase, but by two non-LTR retrotransposons, HeT-A and TART, that transpose specifically to chromosome ends. Successive transpositions result in long head-to-tail arrays of these elements. Thus Drosophila telomeres, like those produced by telomerase, consist of repeated sequences reverse transcribed from RNA templates. The Drosophila repeats, complete and 5′-truncated copies of HeT-A and TART, are more complex than telomerase repeats; nevertheless these evolutionary variants have functional similarities to the more common telomeres. Like other telomeres, the Drosophila arrays are dynamic, fluctuating around an average length that can be changed by changes in the genetic background. Several proteins that interact with telomeres in other species have been found to have homologues that interact with Drosophila telomeres. Although they have hallmarks of non-LTR retrotransposons, HeT-A and TART appear to have a special relationship to Drosophila. Their Gag proteins are efficiently transported into diploid nuclei where HeT-A Gag recruits TART Gag to chromosome ends. Gags of other non-LTR elements remain predominantly in the cytoplasm. These studies provide intriguing evolutionary links between telomeres and retrotransposable elements. PMID:16132810

  12. Neurosteroids; potential underpinning roles in maintaining homeostasis.

    PubMed

    Rahmani, Behrouz; Ghasemi, Rasoul; Dargahi, Leila; Ahmadiani, Abolhassan; Haeri, Ali

    2016-01-01

    The neuroactive steroids which are synthesized in the brain and nervous system are known as "Neurosteroids". These steroids have crucial functions such as contributing to the myelination and organization of the brain connectivity. Under the stressful circumstances, the concentrations of neurosteroid products such as allopregnanolone (ALLO) and allotetrahydrodeoxycorticosterone (THDOC) alter. It has been suggested that these stress-derived neurosteroids modulate the physiological response to stress. Moreover, it has been demonstrated that the hypothalamic-pituitary-adrenal (HPA) axis mediates the physiological adaptation following stress in order to maintain homeostasis. Although several regulatory pathways have been introduced, the exact role of neurosteroids in controlling HPA axis is not clear to date. In this review, we intend to discern specific pathways associated with regulation of HPA axis in which neuroactive steroids have the main role. In this respect, we propose pathways that may be initiated after neurosteroidogenesis in different brain subregions following acute stress which are potentially capable of activating or inhibiting the HPA axis. PMID:26432100

  13. MAVS maintains mitochondrial homeostasis via autophagy.

    PubMed

    Sun, Xiaofeng; Sun, Liwei; Zhao, Yuanyuan; Li, Ying; Lin, Wei; Chen, Dahua; Sun, Qinmiao

    2016-01-01

    Mitochondrial antiviral signalling protein (MAVS) acts as a critical adaptor protein to transduce antiviral signalling by physically interacting with activated RIG-I and MDA5 receptors. MAVS executes its functions at the outer membrane of mitochondria to regulate downstream antiviral signalling, indicating that the mitochondria provides a functional platform for innate antiviral signalling transduction. However, little is known about whether and how MAVS-mediated antiviral signalling contributes to mitochondrial homeostasis. Here we show that the activation of MAVS is sufficient to induce autophagic signalling, which may mediate the turnover of the damaged mitochondria. Importantly, we find MAVS directly interacts with LC3 through its LC3-binding motif 'YxxI', suggesting that MAVS might act as an autophagy receptor to mediate mitochondrial turnover upon excessive activation of RLR signalling. Furthermore, we provide evidence that both MAVS self-aggregation and its interaction with TRAF2/6 proteins are important for MAVS-mediated mitochondrial turnover. Collectively, our findings suggest that MAVS acts as a potential receptor for mitochondria-associated autophagic signalling to maintain mitochondrial homeostasis. PMID:27551434

  14. Virus movement maintains local virus population diversity.

    PubMed

    Snyder, Jamie C; Wiedenheft, Blake; Lavin, Matthew; Roberto, Francisco F; Spuhler, Josh; Ortmann, Alice C; Douglas, Trevor; Young, Mark

    2007-11-27

    Viruses are the largest reservoir of genetic material on the planet, yet little is known about the population dynamics of any virus within its natural environment. Over a 2-year period, we monitored the diversity of two archaeal viruses found in hot springs within Yellowstone National Park (YNP). Both temporal phylogeny and neutral biodiversity models reveal that virus diversity in these local environments is not being maintained by mutation but rather by high rates of immigration from a globally distributed metacommunity. These results indicate that geographically isolated hot springs are readily able to exchange viruses. The importance of virus movement is supported by the detection of virus particles in air samples collected over YNP hot springs and by their detection in metacommunity sequencing projects conducted in the Sargasso Sea. Rapid rates of virus movement are not expected to be unique to these archaeal viruses but rather a common feature among virus metacommunities. The finding that virus immigration rather than mutation can dominate community structure has significant implications for understanding virus circulation and the role that viruses play in ecology and evolution by providing a reservoir of mobile genetic material. PMID:18025457

  15. Protecting America's secrets while maintaining academic freedom.

    PubMed

    Keel, Brooks A

    2004-04-01

    The terrorist attacks of September 11, 2001, and the subsequent anthrax mail attacks, have had a profound impact on Americans' personal and professional lives and have sparked an active debate regarding the delicate balance between the need for national security and the pursuit of academic freedom. Although academic freedom can be defined in many ways, there are four primary tenets of freedom in an academic environment: freedom to research, freedom to publish, freedom to teach, and freedom to speak. Each of these tenets has come under attack in the wake of September 11, 2001. In this report the author further defines academic freedom and reflects upon recent events that have had a real or perceived impact on this freedom, including (1) attempts to categorize and restrict some research as "sensitive," (2) implementation of export control laws and select agent regulations, (3) limitations on the publication of research findings, (4) prohibition of certain foreign nationals from collaborating with U.S. researchers and receiving education and training in U.S. colleges and universities, and (5) restraint of faculty free speech. The author offers some suggestions as to how academia might achieve a proper balance between protecting our national security while promoting and maintaining academic freedom. PMID:15044166

  16. Work Adjustment of the Methadone-Maintained Corporate Employee

    ERIC Educational Resources Information Center

    Yankowitz, Robert; Randell, Joan

    1977-01-01

    The work adjustment of 26 methadone-maintained corporate employees was evaluated. Results indicated: (a) relative to their nonmethadone-maintained coworkers, the methadone-maintained employees had comparable job performance and superior punctuality and attendance; and (b) the methadone-maintained skilled laborers were satisfied with their…

  17. Human glans penis augmentation using injectable hyaluronic acid gel.

    PubMed

    Kim, J J; Kwak, T I; Jeon, B G; Cheon, J; Moon, D G

    2003-12-01

    Although augmentation phalloplasty is not an established procedure, some patients still need enlargement of their penis. Current penile augmentation is girth enhancement of penile body by dermofat graft. We performed this study to identify the efficacy and the patient's satisfaction of human glans penis augmentation with injectable hyaluronic acid gel. In 100 patients of subjective small penis (Group I) and 87 patients of small glans after dermofat graft (Group II), 2 cm(3) of hyaluronic acid gel was injected into the glans penis, subcutaneously. At 1 y after injection, changes of glandular diameter were measured by tapeline. Patient's visual estimation of glandular size (Gr 0-4) and patient's satisfaction (Grade (Gr) 0-4) were evaluated, respectively. Any adverse reactions were also evaluated. The mean age of patients was 42.2 (30-70) y in Group I and 42.13 (28-61) y in Group II. The maximal glandular circumference was significantly increased compared to basal circumference of 9.13+/-0.64 cm in Group I (P<0.01) and 9.49+/-1.05 cm in Group II (P<0.01) at 1 y after injection. Net increase of maximal glandular circumference after glans augmentation was 14.93+/-0.80 mm in Group I and 14.78+/-0.89 mm in Group II. In patient's visual estimation, more than 50% of injected volume was maintained in 95% of Group 1 and 100% of Group II. The percentage of postoperative satisfaction (Gr 4, 5) was 77% in Group 1 and 69% in Group II. There was no abnormal reaction in area feeling, texture, and color. In most cases, initial discoloration by glandular swelling recovered to normal within 2 weeks. There were no signs of inflammation and no serious adverse reactions in all cases. These results suggest that injectable hyaluronic acid gel is a safe and effective material for augmentation of glans penis. PMID:14671664

  18. Cell response to silica gels with varying mechanical properties

    NASA Astrophysics Data System (ADS)

    Lefebvre, Molly Ann

    Sol-gel encapsulation has a variety of applications in biotechnology and medicine: creating biosensors, biocatalysts, and bioartificial organs. However, encapsulated cell viability is a major challenge. Consequently, interactions between cells and their 3D microenvironment were studied through rheological, metabolic activity, and extraction studies to aid in the development of new gel protocols. The cells were encapsulated in variations of three silica sol-gels with varying stiffness. It was hypothesized that the cell viability and the amount of extracted cells would depend on gel stiffness. For two gels, there was no apparent correlation between the gel stiffness and the cell viability and extracted cell quantity. These gels did strongly depend on the varying gel ingredient, polyethylene glycol. The third gel appeared to follow the hypothesized correlation, but it was not statistically significant. Finally, one gel had a significantly longer period of cell viability and higher quantity of extracted cells than the other gels.

  19. In situ injection of phenylboronic acid based low molecular weight gels for efficient chemotherapy.

    PubMed

    Gao, Wenxia; Liang, Yan; Peng, Xinyu; Hu, Yalong; Zhang, Longgui; Wu, Huayue; He, Bin

    2016-10-01

    Injectable low molecular weight gels (LMWGs) based on the derivatives of phenylboronic acid were prepared and used as substrates for efficient in situ chemotherapy. The gelators as well as LMWGs were characterized by (1)H NMR, UV-vis, FTIR, MS and SEM. Anticancer drug doxorubicin hydrochloride (DOX) was encapsulated in the gels. The rheological properties and rapid recovery capability of both blank and drug-loaded gels were tested. The LMWGs were non-toxic to both 3T3 fibroblasts and 4T1 breast cancer cells. The gels were formed rapidly after injected in vivo. The in vivo anticancer activities of DOX-loaded LMWGs were investigated in breast cancer bearing mice. The intratumoral injection of DOX loaded LMWGs with dose of 30 mg/kg revealed that the gels could coat around the tumor tissues to release DOX sustainingly and maintain effective DOX concentration for chemotherapy. The systemic toxicity of DOX was reduced significantly with the in situ administration of LMWGs formulations. The injectable LMWGs exhibited excellent therapeutic efficacy and low side effects in local chemotherapy. PMID:27497056

  20. Heteropoly acids triggered self-assembly of cationic peptides into photo- and electro-chromic gels.

    PubMed

    Li, Jingfang; Xu, Jing; Li, Xiaodong; Gao, Wenmei; Wang, Liyan; Wu, Lixin; Lee, Myongsoo; Li, Wen

    2016-07-01

    A series of cationic peptides with alternating lysines and hydrophobic residues were designed and synthesized. These kinds of short peptides with protonated lysines can complex with anionic heteropoly acids (HPAs) to form a stable gel in water/ethanol mixed solution. Circular dichroism spectroscopy showed that the short peptides adopted a mixed conformation (β-sheet and random-coil) within the gel matrix. Scanning and transmission electron microscopy revealed that the heteropoly acids, acting as nanosized cross-linkers, first initiated the self-assembly of the cationic peptides into spherical nanostructures. Then these nanospheres accumulated with each other through hydrogen bonds and hydrophobic interactions to form large sheet-like assemblies, which further interconnected with each other forming continuous 3D network structures. Fourier-transform infrared spectroscopy showed that the structural integrity of the HPAs was maintained during the gelation process. The resultant hybrid gels showed reversible photo- and elecrtro-chromic properties. X-ray photoelectron spectroscopy revealed that the hybrid gels, capable of persistent and reversible changes of their colour, are attributed to the intervalence charge-transfer transition of the HPAs. Reversible information writing and erasing were demonstrated through a repeated photo-lithograph or electric stimuli without significant loss of the gel performance. PMID:27240759

  1. VB12-coated Gel-Core-SLN containing insulin: Another way to improve oral absorption.

    PubMed

    He, Haibing; Wang, Puxiu; Cai, Cuifang; Yang, Rui; Tang, Xing

    2015-09-30

    To improve the oral absorption of insulin, a novel carrier of Vitamin B12 (VB12) gel core solid lipid nanopaticles (Gel-Core-SLN, GCSLN) was designed with a gel core, lipid matrix and VB12-coated surface. VB12-stearate was synthesized and characterized by infrared spectroscopy (IR), nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS). Sol-gel conversion following ultrasonic heating and double emulsion technology were combined to implant the insulin-containing gel into solid lipid nanoparticles (SLN). The influence of the mode of administration, food, the amount of VB12-stearate and the particle size on the oral absorption of insulin incorporated in the VB12-GCSLN was investigated. The determined partition coefficient (LogP) of VB12-stearate in a dichloromethane (DCM)-water system was 3.4. This new structure of VB12-GCSLN had higher insulin encapsulation efficiency (EE) of 55.9%, a lower burst release of less than 10% in the first 2h. In vivo studies demonstrated that stronger absorption of insulin with a relative pharmacological availability (PA) of 9.31% compared with the normal insulin-loaded SLN and GCSLN and fairly stable blood glucose levels up to 12h were maintained without any sharp fluctuations. This study suggests that VB12-GCSLN containing insulin appears to be a promising nano carrier for oral delivery of biomacromolecules with relatively high pharmacological availability. PMID:26253378

  2. Improving pancreatic islet in vitro functionality and transplantation efficiency by using heparin mimetic peptide nanofiber gels.

    PubMed

    Uzunalli, Gozde; Tumtas, Yasin; Delibasi, Tuncay; Yasa, Oncay; Mercan, Sercan; Guler, Mustafa O; Tekinay, Ayse B

    2015-08-01

    Pancreatic islet transplantation is a promising treatment for type 1 diabetes. However, viability and functionality of the islets after transplantation are limited due to loss of integrity and destruction of blood vessel networks. Thus, it is important to provide a proper mechanically and biologically supportive environment for enhancing both in vitro islet culture and transplantation efficiency. Here, we demonstrate that heparin mimetic peptide amphiphile (HM-PA) nanofibrous network is a promising platform for these purposes. The islets cultured with peptide nanofiber gel containing growth factors exhibited a similar glucose stimulation index as that of the freshly isolated islets even after 7 days. After transplantation of islets to STZ-induced diabetic rats, 28 day-long monitoring displayed that islets that were transplanted in HM-PA nanofiber gels maintained better blood glucose levels at normal levels compared to the only islet transplantation group. In addition, intraperitoneal glucose tolerance test revealed that animals that were transplanted with islets within peptide gels showed a similar pattern with the healthy control group. Histological assessment showed that islets transplanted within peptide nanofiber gels demonstrated better islet integrity due to increased blood vessel density. This work demonstrates that using the HM-PA nanofiber gel platform enhances the islets function and islet transplantation efficiency both in vitro and in vivo. PMID:25931015

  3. Hypoglycemic effect of Aloe vera gel on streptozotocin-induced diabetes in experimental rats.

    PubMed

    Rajasekaran, S; Sivagnanam, K; Ravi, K; Subramanian, S

    2004-01-01

    In the present study an attempt has been made to evaluate the presence of hypoglycemic activity in the alcoholic extract of Aloe vera gel. Effects of oral administration of A. vera extract at a concentration of 200 and 300 mg/kg of body weight on (a) normal fasted rats, (b) oral glucose-loaded rats, and (c) streptozotocin-induced diabetic rats have been studied. A. vera extract maintain the glucose homeostasis by controlling the carbohydrate metabolizing enzymes. PMID:15117555

  4. Influence of gel dimensions on resolution and sample throughput on two-dimensional gels.

    PubMed

    Lee, KiBeom; Pi, KyungBae; Lee, Hong-Gu

    2008-04-01

    To achieve high throughput and economical format of 2-D PAGE, comparison between gel size and resolution was conducted on human breast carcinoma cell line (MCF-7/AZ) proteins. SDS gel length showed a weaker influence of separation length on resolution in the second dimension, and there was little benefit of separation distances greater than 15 to 19 cm. IPG strip separation distances were very important with dramatic increase in resolution of longer gels compared with smaller gels, and maximal resolution was obtained using 18- and 24-cm IPG strips. Loading optimal amount of proteins on 2-D gels can also increase the number of detected spots. Therefore, taken together, compromise 2-D gels are crucial for higher capacity and higher throughput. PMID:18457572

  5. Manual control of catalytic reactions: Reactions by an apoenzyme gel and a cofactor gel

    PubMed Central

    Kobayashi, Yuichiro; Takashima, Yoshinori; Hashidzume, Akihito; Yamaguchi, Hiroyasu; Harada, Akira

    2015-01-01

    Enzymes play a vital role in catalysing almost all chemical reactions that occur in biological systems. Some enzymes must form complexes with non-protein molecules called cofactors to express catalytic activities. Although the control of catalytic reactions via apoenzyme–cofactor complexes has attracted significant attention, the reports have been limited to the microscale. Here, we report a system to express catalytic activity by adhesion of an apoenzyme gel and a cofactor gel. The apoenzyme and cofactor gels act as catalysts when they form a gel assembly, but they lose catalytic ability upon manual dissociation. We successfully construct a system with switchable catalytic activity via adhesion and separation of the apoenzyme gel with the cofactor gel. We expect that this methodology can be applied to regulate the functional activities of enzymes that bear cofactors in their active sites, such as the oxygen transport of haemoglobin or myoglobin and the electron transport of cytochromes. PMID:26537172

  6. Manual control of catalytic reactions: Reactions by an apoenzyme gel and a cofactor gel

    NASA Astrophysics Data System (ADS)

    Kobayashi, Yuichiro; Takashima, Yoshinori; Hashidzume, Akihito; Yamaguchi, Hiroyasu; Harada, Akira

    2015-11-01

    Enzymes play a vital role in catalysing almost all chemical reactions that occur in biological systems. Some enzymes must form complexes with non-protein molecules called cofactors to express catalytic activities. Although the control of catalytic reactions via apoenzyme-cofactor complexes has attracted significant attention, the reports have been limited to the microscale. Here, we report a system to express catalytic activity by adhesion of an apoenzyme gel and a cofactor gel. The apoenzyme and cofactor gels act as catalysts when they form a gel assembly, but they lose catalytic ability upon manual dissociation. We successfully construct a system with switchable catalytic activity via adhesion and separation of the apoenzyme gel with the cofactor gel. We expect that this methodology can be applied to regulate the functional activities of enzymes that bear cofactors in their active sites, such as the oxygen transport of haemoglobin or myoglobin and the electron transport of cytochromes.

  7. Sol-gel antireflective coating on plastics

    DOEpatents

    Ashley, C.S.; Reed, S.T.

    1988-01-26

    An antireflection film made from reliquified sol-gel hydrolyzation, condensation polymeric reaction product of a silicon, alkoxides and/or metal alkoxides, or mixtures thereof. The film is particularly useful for coating plastics.

  8. Magnetic Hyperthermia in ferrofluid-gel composites

    NASA Astrophysics Data System (ADS)

    Nemala, Humeshkar; Wadehra, Anshu; Dixit, Ambesh; Regmi, Rajesh; Vaishnava, Prem; Lawes, Gavin; Naik, Ratna

    2012-02-01

    Magnetic hyperthermia is the generation of heat by an external magnetic field using superparamagnetic nanoparticles. However, there are still questions concerning magnetic hyperthermia in tissue; in particular the confinement of the nanoparticles at mesoscopic scales. We used Agarose and Alginate gels as models for human tissue and embedded magnetic nanoparticles in them. We report the synthesis and characterization of dextran coated iron oxide (Fe3O4) nanoparticles. Characterization of these nanoparticles was done using X-ray diffraction, transmission electron microscopy, magnetometry, and hyperthermia measurements. Temperature dependent susceptibility measurements reveal a sharp anomaly in the ferrofluid sample at the freezing temperature. This is conspicuously absent in the ferrofluid-gel composites. Heat generation studies on these superparamagnetic gel-composites revealed a larger heat production in the ferrofluids(˜4W/g) as compared to the gels(˜1W/g), which we attribute to a reduction in Brownian relaxation for the nanoparticles embedded in Agarose and Alginate.

  9. Turbidimetric studies of Limulus coagulin gel formation.

    PubMed Central

    Moody, T P; Donovan, M A; Laue, T M

    1996-01-01

    The turbidity during trypsin-induced coagulin gel formation was studied over a range of wavelengths. The range of wavelengths used (686-326 nm) also made it possible to investigate the dependence of turbidity on wavelength (the wavelength exponent). Using the results from that work, and structural information on coagulin and the coagulin gel from other studies, a model gel-forming system was designed that consists of species for which the turbidity can be calculated relatively simply. These species include small particles (small in all dimensions relative to the wavelength of incident light); long rods and long random coils (particles that are large in just one dimension relative to the wavelength of incident light); and reflective regions (aggregated material that is large in more than one dimension relative to the wavelength of incident light). The turbidimetric characteristics of the real coagulin gel-forming system are compared with those of the model system. PMID:8889175

  10. Elastocapillary Deformations and Fracture of Soft Gels

    NASA Astrophysics Data System (ADS)

    Daniels, Karen; Grzelka, Marion; Bostwick, Joshua

    When a droplet is placed on the surface of a soft gel, the surface deforms by an amount proportional to the elastocapillary length calculated from the ratio of surface tension and elastic modulus. For sufficiently large deformations, the gel can fracture due to the forces generated under the liquid-gel contact line. We observe that a starburst of channel fractures forms at the surface of the gel, driven by fluid propagating away from the central droplet. To understand the initiation of these cracks, we model the substrate as an incompressible, linear-elastic solid and quantify the elastic response. This provides quantitative agreement with experimental measurements of the number of fracture arms as a function of material properties and geometric parameters. In addition, we find that the initiation process is thermally-activated, with delay time that decreases as a function of the elastocapillary length.

  11. Sol-gel antireflective coating on plastics

    DOEpatents

    Ashley, Carol S.; Reed, Scott T.

    1990-01-01

    An antireflection film made from a reliquified sol-gel hydrolyzation, condensation polymeric reaction product of a silicon, alkoxides and/or metal alkoxides, or mixtures thereof. The film is particularly useful for coating plastics.

  12. Procedure to prepare transparent silica gels

    NASA Technical Reports Server (NTRS)

    Barber, Patrick G. (Inventor); Simpson, Norman R. (Inventor)

    1987-01-01

    This invention relates to the production of silica gels and in particular to a process for the preparation of silica gels which can be used as a crystal growth medium that simulates the convectionless environment of space to produce structurally perfect crystals. Modern utilizations of substances in electronics, such as radio transmitters and high frequency microphones, often require single crystals with controlled purity and structural perfection. The near convectionless environment of silica gel suppresses nucleation, thereby reducing the competitive nature of crystal growth. This competition limits the size and perfection of the crystal; and it is obviously desirable to suppress nucleation until, ideally, only one crystal grows in a predetermined location. A silica gel is not a completely convectionless environment like outer space, but is the closest known environment to that of outer space that can be created on Earth.

  13. Sol-gel deposited electrochromic coatings

    SciTech Connect

    Ozer, N.; Lampert, C.M.

    1995-06-01

    Electrochromic devices have increasing application in display devices, switchable mirrors and smart windows. A variety of vacuum deposition technologies have been used to make electrochromic devices. The sol- gel process offers an alternative approach to the synthesis of optical quality and low cost electrochromic device layers. This study summarizes the developments in sol-gel deposited electrochromic films. The sol-gel process involves the formation of oxide networks upon hydrolysis-condensation of alkoxide precursors. In this study we cover the sol-gel deposited oxides of WO[sub 3], V[sub 2]O[sub 5], TiO[sub 2], Nb[sub 2]O[sub 5], and NiO[sub x].

  14. K-Basin gel formation studies

    SciTech Connect

    Beck, M.A.

    1998-07-23

    A key part of the proposed waste treatment for K Basin sludge is the elimination of reactive uranium metal by dissolution in nitric acid (Fkirnent, 1998). It has been found (Delegard, 1998a) that upon nitric acid dissolution of the sludge, a gel sometimes forms. Gels are known to sometimes impair solid/liquid separation and/or material transfer. The purpose of the work reported here is to determine the cause(s) of the gel formation and to determine operating parameters for the sludge dissolution that avoid formation of gel. This work and related work were planned in (Fkunent, 1998), (Jewett, 1998) and (Beck, 1998a). This report describes the results of the tests in (Beck, 1998a) with non-radioactive surrogates.

  15. Advanced gel propulsion controls for kill vehicles

    NASA Astrophysics Data System (ADS)

    Yasuhara, W. K.; Olson, A.; Finato, S.

    1993-06-01

    A gel propulsion control concept for tactical applications is reviewed, and the status of the individual component technologies currently under development at the Aerojet Propulsion Division is discussed. It is concluded that a gel propellant Divert and Attitude Control Subsystem (DACS) provides a safe, insensitive munitions compliant alternative to current liquid Theater Missile Defense (TMD) DACS approaches. The gel kill vehicle (KV) control system packages a total impulse typical of a tactical weapon interceptor for the ground- or sea-based TMD systems. High density packaging makes it possible to increase firepower and to eliminate long-term high pressure gas storage associated with bipropellant systems. The integrated control subsystem technologies encompass solid propellant gas generators, insulated composite overwrapped propellant tanks, lightweight endoatmospheric thrusters, and insensitive munition gel propellants, which meet the requirements of a deployable, operationally safe KV.

  16. Sample collection system for gel electrophoresis

    SciTech Connect

    Olivares, Jose A.; Stark, Peter C.; Dunbar, John M.; Hill, Karen K.; Kuske, Cheryl R.; Roybal, Gustavo

    2004-09-21

    An automatic sample collection system for use with an electrophoretic slab gel system is presented. The collection system can be used with a slab gel have one or more lanes. A detector is used to detect particle bands on the slab gel within a detection zone. Such detectors may use a laser to excite fluorescently labeled particles. The fluorescent light emitted from the excited particles is transmitted to low-level light detection electronics. Upon the detection of a particle of interest within the detection zone, a syringe pump is activated, sending a stream of buffer solution across the lane of the slab gel. The buffer solution collects the sample of interest and carries it through a collection port into a sample collection vial.

  17. Rheological Characterization of Ethanolamine Gel Propellants

    NASA Astrophysics Data System (ADS)

    V. S Jyoti, Botchu; Baek, Seung Wook

    2016-07-01

    Ethanolamine is considered to be an environmentally friendly propellant system because it has low toxicity and is noncarcinogenic in nature. In this article, efforts are made to formulate and prepare ethanolamine gel systems, using pure agarose and hybrids of paired gelling agents (agarose + polyvinylpyrrolidine (PVP), agarose + SiO2, and PVP + SiO2), that exhibit a measurable yield stress, thixotropic behavior under shear rate ranges of 1-1,000 s-1 and a viscoelastic nature. To achieve these goals, multiple rheological experiments (including flow and dynamic studies) are performed. In this article, results are presented from experiments measuring the apparent viscosity, yield stress, thixotropy, dynamic strain, frequency sweep, and tan δ behaviors, as well as the effects of the test temperature, in the gel systems. The results show that the formulated ethanolamine gels are thixotropic in nature with yield stress between 30 and 60 Pa. The apparent viscosity of the gel decreases as the test temperature increases, and the apparent activation energy is the lowest for the ethanolamine-(PVP + SiO2) gel system. The dynamic rheology study shows that the type of gellant, choice of hybrid gelling materials and their concentration, applied frequencies, and strain all vitally affect the viscoelastic properties of the ethanolamine gel systems. In the frequency sweep experiment, the ethanolamine gels to which agarose, agarose + PVP, and agarose + SiO2 were added behave like linear frequency-dependent viscoelastic liquids, whereas the ethanolamine gel to which PVP + SiO2 was added behaves like a nearly frequency-independent viscoelastic solid. The variation in the tan δ of these gelled propellants as a function of frequency is also discussed.

  18. Annular gel reactor for chemical pattern formation

    DOEpatents

    Nosticzius, Zoltan; Horsthemke, Werner; McCormick, William D.; Swinney, Harry L.; Tam, Wing Y.

    1990-01-01

    The present invention is directed to an annular gel reactor suitable for the production and observation of spatiotemporal patterns created during a chemical reaction. The apparatus comprises a vessel having at least a first and second chamber separated one from the other by an annular polymer gel layer (or other fine porous medium) which is inert to the materials to be reacted but capable of allowing diffusion of the chemicals into it.

  19. Sol-Gels for Optical Sensors

    NASA Astrophysics Data System (ADS)

    Podbielska, Halina; Ulatowska-Jarża, Agnieszka; Müller, Gerhard; Eichler, Hans J.

    Sol-gel process allows for formation of glassy and ceramics materials in temperatures much lower than offered by conventional melting techniques. The first paper on sol-gels was published over 150 years ago by Ebelmen, however, the rapid development of this technology and applications occurred in the last few years. There is a broad range of possible applications of solgel derived materials, what marked this technology as one of the most promising fields of contemporary material sciences

  20. Maintaining Homeostasis by Decision-Making

    PubMed Central

    Korn, Christoph W.; Bach, Dominik R.

    2015-01-01

    Living organisms need to maintain energetic homeostasis. For many species, this implies taking actions with delayed consequences. For example, humans may have to decide between foraging for high-calorie but hard-to-get, and low-calorie but easy-to-get food, under threat of starvation. Homeostatic principles prescribe decisions that maximize the probability of sustaining appropriate energy levels across the entire foraging trajectory. Here, predictions from biological principles contrast with predictions from economic decision-making models based on maximizing the utility of the endpoint outcome of a choice. To empirically arbitrate between the predictions of biological and economic models for individual human decision-making, we devised a virtual foraging task in which players chose repeatedly between two foraging environments, lost energy by the passage of time, and gained energy probabilistically according to the statistics of the environment they chose. Reaching zero energy was framed as starvation. We used the mathematics of random walks to derive endpoint outcome distributions of the choices. This also furnished equivalent lotteries, presented in a purely economic, casino-like frame, in which starvation corresponded to winning nothing. Bayesian model comparison showed that—in both the foraging and the casino frames—participants’ choices depended jointly on the probability of starvation and the expected endpoint value of the outcome, but could not be explained by economic models based on combinations of statistical moments or on rank-dependent utility. This implies that under precisely defined constraints biological principles are better suited to explain human decision-making than economic models based on endpoint utility maximization. PMID:26024504

  1. Andean flat subduction maintained by slab tunneling

    NASA Astrophysics Data System (ADS)

    Schepers, Gerben; van Hinsbergen, Douwe; Kosters, Martha; Boschman, Lydian; McQuarrie, Nadine; Spakman, Wim

    2016-04-01

    In two segments below the Andean mountain belt, the Nazca Plate is currently subducting sub-horizontally below South America over a distance of 200-300 km before the plate bends into the mantle. Such flat slab segments have pronounced effects on orogenesis and magmatism and are widely believed to be caused by the downgoing plate resisting subduction due to its local positive buoyancy. In contrast, here we show that flat slabs primarily result from a local resistance against rollback rather than against subduction. From a kinematic reconstruction of the Andean fold-thrust belt we determine up to ~390 km of shortening since ~50 Ma. During this time the South American Plate moved ~1400 km westward relative to the mantle, thus forcing ~1000 km of trench retreat. Importantly, since the 11-12 Ma onset of flat slab formation, ~1000 km of Nazca Plate subduction occurred, much more than the flat slab lengths, which leads to our main finding that the flat slabs, while being initiated by arrival of buoyant material at the trench, are primarily maintained by locally impeded rollback. We suggest that dynamic support of flat subduction comes from the formation of slab tunnels below segments with the most buoyant material. These tunnels trap mantle material until tearing of the tunnel wall provides an escape route. Fast subduction of this tear is followed by a continuous slab and the process can recur during ongoing rollback of the 7000 km wide Nazca slab at segments with the most buoyant subducting material, explaining the regional and transient character of flat slabs. Our study highlights the importance of studying subduction dynamics in absolute plate motion context.

  2. Maintaining homeostasis by decision-making.

    PubMed

    Korn, Christoph W; Bach, Dominik R

    2015-05-01

    Living organisms need to maintain energetic homeostasis. For many species, this implies taking actions with delayed consequences. For example, humans may have to decide between foraging for high-calorie but hard-to-get, and low-calorie but easy-to-get food, under threat of starvation. Homeostatic principles prescribe decisions that maximize the probability of sustaining appropriate energy levels across the entire foraging trajectory. Here, predictions from biological principles contrast with predictions from economic decision-making models based on maximizing the utility of the endpoint outcome of a choice. To empirically arbitrate between the predictions of biological and economic models for individual human decision-making, we devised a virtual foraging task in which players chose repeatedly between two foraging environments, lost energy by the passage of time, and gained energy probabilistically according to the statistics of the environment they chose. Reaching zero energy was framed as starvation. We used the mathematics of random walks to derive endpoint outcome distributions of the choices. This also furnished equivalent lotteries, presented in a purely economic, casino-like frame, in which starvation corresponded to winning nothing. Bayesian model comparison showed that--in both the foraging and the casino frames--participants' choices depended jointly on the probability of starvation and the expected endpoint value of the outcome, but could not be explained by economic models based on combinations of statistical moments or on rank-dependent utility. This implies that under precisely defined constraints biological principles are better suited to explain human decision-making than economic models based on endpoint utility maximization. PMID:26024504

  3. Maintaining professional activity during breast cancer treatment.

    PubMed

    Ganem, G; Antoine, E-C; Touboul, C; Naman, H; Dohollou, N; Facchini, T; Coscas, Y; Lortholary, A; Catala, S; Jacquot, S; Lhomel, C; Eisinger, F

    2016-05-01

    The question of returning to work and pursuing professional activity during cancer treatment is an increasingly important consideration. The present work focuses on factors affecting the feasibility of maintaining professional activity during treatment for breast cancer, for women who wished to do so. Written questionnaires were collected from 216 patients between March and November 2012. Since the onset of their treatment, 31.4% of the women (68/216) had not been on sick-leave. The main factors associated with the pursuit of professional activity were: considering the availability of their physician to answer questions as unimportant [OR = 18.83 (3.60-98.53); P ≤ 0.05]; considering the diagnosis of cancer as likely to have a weak impact on career perspectives [OR = 4.07 (2.49-6.64); P ≤ 0.05]; not having any children in the household [OR = 3.87 (2.38-6.28); P ≤ 0.05]; being in a managerial position [OR = 3.13 (1.88-5.21); P ≤ 0.05]. Negative predictive factors were: physician mentioning adverse effects of the treatment [OR = 0.31 (0.16-0.58); P ≤ 0.05], and patient rating workload as high [OR = 0.26 (0.15-0.46); P ≤ 0.05]. As a result of advances in therapeutic strategies, more patients will expect healthcare professionals, as well as employers and occupational health societies, to prioritise issues pertaining to the maintenance of professional activities during cancer treatment. PMID:26891443

  4. Maintaining the cold chain for vaccines.

    PubMed

    Petrović, Vladimir; Seguljev, Zorica; Gajin, Branka

    2005-01-01

    Cold chain for vaccines a is a system for storing and transporting vaccines at very low temperatures to maintain their effectiveness before use. Because vaccines are sensitive biological substances, their exposition to high temperatures directly affects the quality of vaccines and safety of immunization. The goal of this study was to assess the safety of cold chain for vaccines within the cold chain system in two services of Health Center Novi Sad. Cold Chain Monitors (CCM) and Freeze Watch (FW) indicators were used. A total of 155 (94.5%) Cold Chain Monitors (CCM) and 100 (95.2%) Freeze Watch (FW) indicators were analyzed. Only one CCM showed a breack in cold chain. A total of 3 CCMs indicated risk of vaccine wastage. A total of 9 CCMs were colorized without risk of vaccine wastage. FWs were positive in a high percentage in both services of Health Center Novi Sad. FWs were exposed to low temperatures during transport. Statistically significant differencies in the number of exposed CCMs to high temperatures and the number of exposed FWs to low temperatures were observed in these two services. A statistically significant difference in number of FWs exposed to low temperatures was observed in regard to the period of transport and the period of storage at the vaccination stations. The study shows high level of safety of the cold chain in two services of Health Center Novi Sad Cold Chain Monitor is a reliable indicator of the quality of cold chain for vaccines. Freeze Watch is a reliable indicator of the quality of cold chain during storage of vaccines, but not during their transport. PMID:16296574

  5. Cavitation of a Physically Associating Gel

    NASA Astrophysics Data System (ADS)

    Mishra, Satish; Kundu, Santanu

    Self-assembly of block copolymers in selective solvents form ordered structures such as micelles, vesicles, and physically crosslinked gels due to difference in their interaction with solvents. These gels have wide range of applications in tissue engineering, food science and biomedical field due to their tunable properties and responsiveness with changing environmental conditions. Pressurization of a defect inside a physically associating gel can lead to elastic instability (cavitation) leading to failure of the gel. The failure behavior involves dissociation of physical networks. A thermoreversible, physically associating gel with different volume fractions of a triblock copolymer, poly (methyl methacrylate)-poly (n-butyl acrylate)-poly (methyl methacrylate) [PMMA-PnBA-PMMA] in 2-ethyl 1-hexanol, a midblock selective solvent, is considered here. Mechanical properties were investigated using shear rheology and cavitation experiments. The experimental data is fitted with a constitutive model that captures the stiffening behavior followed by softening behavior of a physical gel. Finite element analysis has been performed on cavitation rheology geometry to capture the failure behavior and to calculate energy release rate during cavitation experiments.

  6. Treatment of osteochondral injuries with platelet gel

    PubMed Central

    Danieli, Marcus Vinicius; da Rosa Pereira, Hamilton; de Sá Carneiro, Carlos Augusto; Felisbino, Sérgio Luiz; Deffune, Elenice

    2014-01-01

    OBJECTIVES: Treatments for injured articular cartilage have not advanced to the point that efficient regeneration is possible. However, there has been an increase in the use of platelet-rich plasma for the treatment of several orthopedic disorders, including chondral injuries. Our hypothesis is that the treatment of chondral injuries with platelet gel results in higher-quality repair tissue after 180 days compared with chondral injuries not treated with gel. METHODS: A controlled experimental laboratory study was performed on 30 male rabbits to evaluate osteochondral injury repair after treatment with or without platelet gel. Osteochondral injuries were surgically induced in both knees of each rabbit at the medial femoral condyle. The left knee injury was filled with the platelet gel, and the right knee was not treated. Microscopic analysis of both knee samples was performed after 180 days using a histological grading scale. RESULTS: The only histological evaluation criterion that was not significantly different between treatments was metachromasia. The group that was treated with platelet gel exhibited superior results in all other criteria (cell morphology, surface regularity, chondral thickness and repair tissue integration) and in the total score. CONCLUSION: The repair tissue was histologically superior after 180 days in the study group treated with platelet gel compared with the group of untreated injuries. PMID:25518022

  7. Basic investigations on LCV micelle gel

    NASA Astrophysics Data System (ADS)

    Ebenezer, S. B.; Rafic, M. K.; Ravindran, P. B.

    2013-06-01

    The aim of this study was to investigate the feasibility of using Leuco Crystal Violet (LCV) based micelle gel dosimeter as a quality assurance tool in radiotherapy applications. Basic properties such as absorption coefficient and diffusion of LCV gel phantom over time were evaluated. The gel formulation consisted of 25 mM Trichloroacetic acid, 1mM LCV, 4 mM Triton X-100, 4% gelatin by mass and distilled water. The advantages of using this gel are its tissue equivalence, easy and less preparation time, lower diffusion rate and it can be read with an optical scanner. We were able to reproduce some of the results of Babic et al. The peak absorption was found to be at 600 nm and hence a matrix of yellow LEDs was used as light source. The profiles obtained from projection images confirmed the diffusion of LCV gel after 6 hours of irradiation. Hence the LCV gel phantom should be read before 6 hours post irradiation to get accurate dose information as suggested previously.

  8. Actuator device utilizing a conductive polymer gel

    DOEpatents

    Chinn, Douglas A.; Irvin, David J.

    2004-02-03

    A valve actuator based on a conductive polymer gel is disclosed. A nonconductive housing is provided having two separate chambers separated by a porous frit. The conductive polymer is held in one chamber and an electrolyte solution, used as a source of charged ions, is held in the second chamber. The ends of the housing a sealed with a flexible elastomer. The polymer gel is further provide with electrodes with which to apply an electrical potential across the gel in order to initiate an oxidation reaction which in turn drives anions across the porous frit and into the polymer gel, swelling the volume of the gel and simultaneously contracting the volume of the electrolyte solution. Because the two end chambers are sealed the flexible elastomer expands or contracts with the chamber volume change. By manipulating the potential across the gel the motion of the elastomer can be controlled to act as a "gate" to open or close a fluid channel and thereby control flow through that channel.

  9. The Gel Electrophoresis Markup Language (GelML) from the Proteomics Standards Initiative

    PubMed Central

    Gibson, Frank; Hoogland, Christine; Martinez-Bartolomé, Salvador; Medina-Aunon, J. Alberto; Albar, Juan Pablo; Babnigg, Gyorgy; Wipat, Anil; Hermjakob, Henning; Almeida, Jonas S; Stanislaus, Romesh; Paton, Norman W; Jones, Andrew R

    2011-01-01

    The Human Proteome Organisation’s Proteomics Standards Initiative (HUPO-PSI) has developed the GelML data exchange format for representing gel electrophoresis experiments performed in proteomics investigations. The format closely follows the reporting guidelines for gel electrophoresis, which are part of the Minimum Information About a Proteomics Experiment (MIAPE) set of modules. GelML supports the capture of metadata (such as experimental protocols) and data (such as gel images) resulting from gel electrophoresis so that laboratories can be compliant with the MIAPE Gel Electrophoresis guidelines, while allowing such data sets to be exchanged or downloaded from public repositories. The format is sufficiently flexible to capture data from a broad range of experimental processes, and complements other PSI formats for mass spectrometry data and the results of protein and peptide identifications to capture entire gel-based proteome workflows. GelML has resulted from the open standardisation process of PSI consisting of both public consultation and anonymous review of the specifications. PMID:20677327

  10. Slow Release of Permanganate from Injectable Fumed Silica Gel: Rheological Properties and Release Dynamics

    NASA Astrophysics Data System (ADS)

    Yang, S.; Zhong, L.; Oostrom, M.; Li, G.

    2014-12-01

    ISCO (In Situ Chemical Oxidation) has been proved to be a useful remediation technology in destroying most prevalent aqueous organic contaminants. For permanganate (MnO4-) in particular, the chemistry of degradative oxidation is well established for cleaning up groundwater containing trichloroethene (TCE) and tetrachloroethene (PCE). However the long-term effectiveness of the application of this oxidant has been questioned due to the observed post remediation rebound of contaminant concentrations. To improve the efficiency of ISCO using MnO4-under specific site conditions, the technology of emplacing slow-releasing permanganate in an aquifer has been studied. We have developed an injectable slow-release permanganate slurry/gel (ISRPG) by mixing KMnO4 with fumed silica in water. Ideally, the slurry/gel forms would release low concentration of MnO4- by diffusion to maintain a desired concentration level of the agent within the chemically active zone. We have investigated the properties and tested the application of this ISRPG in laboratory studies. Rheological study indicated ISRPG has high viscosity and shear thinning property. The viscosity of silica gel could be lowered by mechanical mixing thus making it easy for subsurface injection. Batch tests revealed that MnO4- was diffused from ISRPG and the gel did not disperse but maintained its initial shape. In column experiments we showed that permanganate release covered 6 times more effluent pore volumes when ISRPG was injected compared to MnO4- solution injection. We also observed TCE degradation by released MnO4-, and the remedial performance occurred over a much longer timeframe with ISRPG compared to MnO4- solution injection. In 2-D flow cell tests we demonstrated that water flows around the injected gel, carrying MnO4- diffused out from the gel and forming a downstream oxidant plume, while the gel was stationary. ISRPG slowly released low concentrations of permanganate to maintain a predetermined level of the

  11. Preparation and characterization of lidocaine rice gel for oral application.

    PubMed

    Okonogi, Siriporn; Kaewpinta, Adchareeya; Yotsawimonwat, Songwut; Khongkhunthian, Sakornrat

    2015-12-01

    The objective of the present study was to prepare buccal anesthetic gels using rice as gelling agent. Rice grains of four rice varieties, Jasmine (JM), Saohai (SH), Homnil (HN), and Doisket (DS) were chemically modified. Buccal rice gels, containing lidocaine hydrochloride as local anesthetic drug were formulated using the respective modified rice varieties. The gels were evaluated for outer appearance, pH, color, gel strength, foaming property, adhesion, in vitro drug release and in vivo efficacy. It was found that the developed rice gels possessed good texture. Rice varieties showed influence on gel strength, color, turbidity, adhesive property, release property, and anesthetic efficacy. JM gel showed the lowest turbidity with light transmission of 86.76 ± 1.18% whereas SH gel showed the highest gel strength of 208.78 ± 10.42 g/cm(2). Lidocaine hydrochloride can cause a decrease in pH and adhesive property but an increase in turbidity of the gels. In vitro drug release profile within 60 min of lidocaine SH gel and lidocaine HN gel showed that lidocaine could be better released from SH gel. Evaluation of in vivo anesthetic efficacy in 100 normal volunteers indicates that both lidocaine rice gels have high efficacy but different levels. Lidocaine SH gel possesses faster onset of duration and longer duration of action than lidocaine HN gel. PMID:26781924

  12. 21 CFR 524.660b - Dimethyl sulfoxide gel.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Dimethyl sulfoxide gel. 524.660b Section 524.660b... Dimethyl sulfoxide gel. (a) Specifications. Dimethyl sulfoxide gel, veterinary contains 90 percent dimethyl sulfoxide in an aqueous gel. (b) Sponsor. See No. 000856 in § 510.600(c) of this chapter. (c) Conditions...

  13. Uncertainty in 3D gel dosimetry

    NASA Astrophysics Data System (ADS)

    De Deene, Yves; Jirasek, Andrew

    2015-01-01

    Three-dimensional (3D) gel dosimetry has a unique role to play in safeguarding conformal radiotherapy treatments as the technique can cover the full treatment chain and provides the radiation oncologist with the integrated dose distribution in 3D. It can also be applied to benchmark new treatment strategies such as image guided and tracking radiotherapy techniques. A major obstacle that has hindered the wider dissemination of gel dosimetry in radiotherapy centres is a lack of confidence in the reliability of the measured dose distribution. Uncertainties in 3D dosimeters are attributed to both dosimeter properties and scanning performance. In polymer gel dosimetry with MRI readout, discrepancies in dose response of large polymer gel dosimeters versus small calibration phantoms have been reported which can lead to significant inaccuracies in the dose maps. The sources of error in polymer gel dosimetry with MRI readout are well understood and it has been demonstrated that with a carefully designed scanning protocol, the overall uncertainty in absolute dose that can currently be obtained falls within 5% on an individual voxel basis, for a minimum voxel size of 5 mm3. However, several research groups have chosen to use polymer gel dosimetry in a relative manner by normalizing the dose distribution towards an internal reference dose within the gel dosimeter phantom. 3D dosimetry with optical scanning has also been mostly applied in a relative way, although in principle absolute calibration is possible. As the optical absorption in 3D dosimeters is less dependent on temperature it can be expected that the achievable accuracy is higher with optical CT. The precision in optical scanning of 3D dosimeters depends to a large extend on the performance of the detector. 3D dosimetry with X-ray CT readout is a low contrast imaging modality for polymer gel dosimetry. Sources of error in x-ray CT polymer gel dosimetry (XCT) are currently under investigation and include inherent

  14. Fabricating porous materials using interpenetrating inorganic-organic composite gels

    DOEpatents

    Seo, Dong-Kyun; Volosin, Alex

    2016-06-14

    Porous materials are fabricated using interpenetrating inorganic-organic composite gels. A mixture or precursor solution including an inorganic gel precursor, an organic polymer gel precursor, and a solvent is treated to form an inorganic wet gel including the organic polymer gel precursor and the solvent. The inorganic wet gel is then treated to form a composite wet gel including an organic polymer network in the body of the inorganic wet gel, producing an interpenetrating inorganic-organic composite gel. The composite wet gel is dried to form a composite material including the organic polymer network and an inorganic network component. The composite material can be treated further to form a porous composite material, a porous polymer or polymer composite, a porous metal oxide, and other porous materials.

  15. Recycling of superfine resolution agarose gel.

    PubMed

    Seng, T-Y; Singh, R; Faridah, Q Z; Tan, S-G; Alwee, S S R S

    2013-01-01

    Genetic markers are now routinely used in a wide range of applications, from forensic DNA analysis to marker-assisted plant and animal breeding. The usual practice in such work is to extract the DNA, prime the markers of interest, and sift them out by electrically driving them through an appropriate matrix, usually a gel. The gels, made from polyacrylamide or agarose, are of high cost, limiting their greater applications in molecular marker work, especially in developing countries where such technology has great potential. Trials using superfine resolution (SFR) agarose for SSR marker screening showed that it is capable of resolving SSR loci and can be reused up to 14 times, thus greatly reducing the cost of each gel run. Furthermore, for certain applications, low concentrations of agarose sufficed and switching to lithium borate buffer, instead of the conventional Tris-borate-ethylenediaminetetraacetic acid buffer, will further save time and cost. The 2.5% gel was prepared following the Agarose SFR(TM) manual by adding 2.5 g agarose powder into 100 mL 1X lithium borate buffer in a 250-mL flask with rapid stirring. Two midigels (105 x 83 mm, 17 wells) or 4 minigels (50 x 83 mm, 8 wells), 4 mm thickness can be prepared from 100 mL gel solution. A total of 1680 PCR products amplified using 140 SSR markers from oil palm DNA samples were tested in this study using SFR recycled gel. As average, the gel can be recycled 8 times with good resolution, but can be recycled up to 14 times before the resolutions get blurred. PMID:23546970

  16. Optimal processing for gel electrophoresis images: Applying Monte Carlo Tree Search in GelApp.

    PubMed

    Nguyen, Phi-Vu; Ghezal, Ali; Hsueh, Ya-Chih; Boudier, Thomas; Gan, Samuel Ken-En; Lee, Hwee Kuan

    2016-08-01

    In biomedical research, gel band size estimation in electrophoresis analysis is a routine process. To facilitate and automate this process, numerous software have been released, notably the GelApp mobile app. However, the band detection accuracy is limited due to a band detection algorithm that cannot adapt to the variations in input images. To address this, we used the Monte Carlo Tree Search with Upper Confidence Bound (MCTS-UCB) method to efficiently search for optimal image processing pipelines for the band detection task, thereby improving the segmentation algorithm. Incorporating this into GelApp, we report a significant enhancement of gel band detection accuracy by 55.9 ± 2.0% for protein polyacrylamide gels, and 35.9 ± 2.5% for DNA SYBR green agarose gels. This implementation is a proof-of-concept in demonstrating MCTS-UCB as a strategy to optimize general image segmentation. The improved version of GelApp-GelApp 2.0-is freely available on both Google Play Store (for Android platform), and Apple App Store (for iOS platform). PMID:27251892

  17. Evolution of gel structure during thermal processing of Na-geopolymer gels.

    PubMed

    Duxson, Peter; Lukey, Grant C; van Deventer, Jannie S J

    2006-10-10

    The present work examines how the gel structure and phase composition of Na-geopolymers derived from metakaolin with varied Si/Al ratio evolve with exposure to temperatures up to 1000 degrees C. Gels were thermally treated and characterized using quantitative XRD, DTA, and FTIR to elucidate the changes in gel structure, phase composition, and porosity at each stage of heating. It is found that the phase stability, defined by the amount and onset temperature of crystallization, is improved at higher Si/Al ratios. Two different mechanisms of densification have been isolated by FTIR, related to viscous flow and collapse of the highly distributed pore network in the gel. Gels with low Si/Al ratio only experience viscous flow that correlates with low thermal shrinkage. Gels at a higher Si/Al ratio, which have a homogeneous microstructure composed of a highly distributed porosity, undergo both densification processes corresponding to a large extent of thermal shrinkage during densification. This work elucidates the intimate relationship between gel microstructure, chemistry, and thermal evolution of Na-geopolymer gels. PMID:17014113

  18. Silica gel-encapsulated AtzA biocatalyst for atrazine biodegradation.

    PubMed

    Reátegui, Eduardo; Reynolds, Erik; Kasinkas, Lisa; Aggarwal, Amit; Sadowsky, Michael J; Aksan, Alptekin; Wackett, Lawrence P

    2012-10-01

    Encapsulation of recombinant Escherichia coli cells expressing a biocatalyst has the potential to produce stable, long-lasting enzyme activity that can be used for numerous applications. The current study describes the use of this technology with recombinant E. coli cells expressing the atrazine-dechlorinating enzyme AtzA in a silica/polymer porous gel. This novel recombinant enzyme-based method utilizes both adsorption and degradation to remove atrazine from water. A combination of silica nanoparticles (Ludox TM40), alkoxides, and an organic polymer was used to synthesize a porous gel. Gel curing temperatures of 23 or 45 °C were used either to maintain cell viability or to render the cells non-viable, respectively. The enzymatic activity of the encapsulated viable and non-viable cells was high and extremely stable over the time period analyzed. At room temperature, the encapsulated non-viable cells maintained a specific activity between (0.44 ± 0.06) μmol/g/min and (0.66 ± 0.12) μmol/g/min for up to 4 months, comparing well with free, viable cell-specific activities (0.61 ± 0.04 μmol/g/min). Gels cured at 45 °C had excellent structural rigidity and contained few viable cells, making these gels potentially compatible with water treatment facility applications. When encapsulated, non-viable cells were assayed at 4 °C, the activity increased threefold over free cells, potentially due to differences in lipid membranes as shown by FTIR spectroscopy and electron microscopy. PMID:22228259

  19. AMPK directly inhibits NDPK through a phosphoserine switch to maintain cellular homeostasis

    PubMed Central

    Onyenwoke, Rob U.; Forsberg, Lawrence J.; Liu, Lucy; Williams, Tyisha; Alzate, Oscar; Brenman, Jay E.

    2012-01-01

    AMP-activated protein kinase (AMPK) is a key energy sensor that regulates metabolism to maintain cellular energy balance. AMPK activation has also been proposed to mimic benefits of caloric restriction and exercise. Therefore, identifying downstream AMPK targets could elucidate new mechanisms for maintaining cellular energy homeostasis. We identified the phosphotransferase nucleoside diphosphate kinase (NDPK), which maintains pools of nucleotides, as a direct AMPK target through the use of two-dimensional differential in-gel electrophoresis. Furthermore, we mapped the AMPK/NDPK phosphorylation site (serine 120) as a functionally potent enzymatic “off switch” both in vivo and in vitro. Because ATP is usually the most abundant cellular nucleotide, NDPK would normally consume ATP, whereas AMPK would inhibit NDPK to conserve energy. It is intriguing that serine 120 is mutated in advanced neuroblastoma, which suggests a mechanism by which NDPK in neuroblastoma can no longer be inhibited by AMPK-mediated phosphorylation. This novel placement of AMPK upstream and directly regulating NDPK activity has widespread implications for cellular energy/nucleotide balance, and we demonstrate in vivo that increased NDPK activity leads to susceptibility to energy deprivation–induced death. PMID:22114351

  20. Sol-gel processing of metal sulfides

    NASA Astrophysics Data System (ADS)

    Stanic, Vesha

    Metal sulfides were synthesised via a sol-gel process using various metal alkoxides and hydrogen sulfide in toluene. Colloidal gels were prepared from germanium ethoxide, germanium isopropoxide, zinc tert-butoxide and tungsten (VI) ethoxide, whereas colloidal powder was produced from tungsten (V) dichloride ethoxide. Special precautions were necessary to protect the reaction mixture from water contamination which produced metal oxides. Results indicated that the main source of water is the hydrogen sulfide gas. In addition, synthesis of metal sulfides from a mixture of metal oxide and sulfide was demonstrated by the example of monoclinic germanium disulfide. It was produced by reaction of the sol-gel product with sulfur. Heat treatment of the sol-gel product and sulfur yielded single phase GeSsb2. The sol-gel prepared materials and their heat treated products were characterized by various methods. A chemical kinetics study of the functional groups -OR, -SH and Ssp{2-} was carried out for the sol-gel processing of GeSsb2 from of hydrogen sulfide and two different alkoxides, germanium ethoxide and germanium isopropoxide. The study was performed for different concentrations of precursors at different molar ratios and temperatures. The results indicate that the proposed reaction mechanism was simplified under appropriate reaction conditions. Experimentally determined rate constants of thiolysis and condensations demonstrate that thiolysis is slow and that condensations are fast steps, regardless of the studied reaction conditions. A study of the temperature effect on the reaction rate constant shows that it increases with temperature in accord with both Arrhenius law and transition-state theory. Activation energies, Esba, and activation parameters DeltaSsp{ddagger}, DeltaHsp{ddagger} and DeltaGsp{ddagger}, were determined for thiolysis and condensation reactions. The potentiometric tiration method was used for quantitative determination of germanium sulfide and

  1. Reversible Gel-Sol Transition of a Photo-Responsive DNA Gel.

    PubMed

    Kandatsu, Daisuke; Cervantes-Salguero, Keitel; Kawamata, Ibuki; Hamada, Shogo; Nomura, Shin-Ichiro M; Fujimoto, Kenzo; Murata, Satoshi

    2016-06-16

    Stimuli-responsive DNA gels that can undergo a sol-gel transition in response to photo-irradiation provide a way to engineer functional gel material with fully designed DNA base sequences. We propose an X-shaped DNA motif that turns into a gel by hybridization of self-complementary sticky ends. By embedding a photo-crosslinking artificial base in the sticky-end sequence, repetitive gel-sol transitions are achieved through UV irradiation at different wavelengths. The concentration of the DNA motif necessary for gelation is as low as 40 μm after modification of the geometrical properties of the motif. The physical properties, such as swelling degree and diffusion coefficient, were assessed experimentally. PMID:27123549

  2. Comparison of electrical conductivities of various brain phantom gels: Developing a ‘Brain Gel Model’

    PubMed Central

    Kandadai, Madhuvanthi A.; Raymond, Jason L.; Shaw, George J.

    2012-01-01

    The use of conducting gels to mimic brain and other tissues is of increasing interest in the development of new medical devices. Currently, there are few such models that can be utilized at physiologic temperatures. In this work, the conductivities of agar, agarose and gelatin gels were manipulated by varying NaCl concentration from 0–1 mg/ml. The AC conductivity was measured at room and physiological temperatures (37°C) in the 100–500 Hz frequency range. Conductivity (σ) was nearly independent of frequency but increased linearly with NaCl concentration and was higher at physiological temperatures in these gels. A formula for predicting conductivity as a function of NaCl concentration was derived for each gel type. The overall goal is to develop a ‘brain gel model’, for studying low frequency electrical properties of the brain and other tissues at physiological temperatures. PMID:23139442

  3. Comparison of electrical conductivities of various brain phantom gels: Developing a 'Brain Gel Model'

    PubMed

    Kandadai, Madhuvanthi A; Raymond, Jason L; Shaw, George J

    2012-12-01

    The use of conducting gels to mimic brain and other tissues is of increasing interest in the development of new medical devices. Currently, there are few such models that can be utilized at physiologic temperatures. In this work, the conductivities of agar, agarose and gelatin gels were manipulated by varying NaCl concentration from 0-1 mg/ml. The AC conductivity was measured at room and physiological temperatures (37°C) in the 100-500 Hz frequency range. Conductivity (σ) was nearly independent of frequency but increased linearly with NaCl concentration and was higher at physiological temperatures in these gels. A formula for predicting conductivity as a function of NaCl concentration was derived for each gel type. The overall goal is to develop a 'brain gel model', for studying low frequency electrical properties of the brain and other tissues at physiological temperatures. PMID:23139442

  4. Enhanced detection of glycoproteins in polyacrylamide gels.

    PubMed

    Muñoz, G; Marshall, S; Cabrera, M; Horvat, A

    1988-05-01

    A highly sensitive and simple method to enhance detection of glycoproteins resolved by either one- or two-dimensional polyacrylamide gel electrophoresis is described. The method is a modification of the procedure described by D. Fargeaud et al. (D. Fargeaud, J. C. Benoit, F. Kato, and G. Chappuis (1984) Arch. Virol. 80, 69-82) that uses concanavalin A conjugated with fluorescein isothyocyanate to detect the carbohydrate moiety of glycoproteins. Briefly, the electrophoresed gel is exposed to the fluorescent lectin, thoroughly washed, and sequentially transferred to 50% methanol in deionized water and to absolute methanol. The result is an abrupt dehydration of the gel which turns evenly white and stiff. At least a twofold enhancement of fluorescence is obtained as detected by exposing the treated gel to an appropriate uv source. The sensitivity of the procedure allows us to detect purified immunoglobulin molecules by their carbohydrate content in the range of 0.2 microgram of total protein. The specificity of the detection is demonstrated by a comparison with the corresponding polypeptide profile obtained by silver nitrate staining of the gel. PMID:3394948

  5. Structural evolution of Colloidal Gels under Flow

    NASA Astrophysics Data System (ADS)

    Boromand, Arman; Maia, Joao; Jamali, Safa

    Colloidal suspensions are ubiquitous in different industrial applications ranging from cosmetic and food industries to soft robotics and aerospace. Owing to the fact that mechanical properties of colloidal gels are controlled by its microstructure and network topology, we trace the particles in the networks formed under different attraction potentials and try to find a universal behavior in yielding of colloidal gels. Many authors have implemented different simulation techniques such as molecular dynamics (MD) and Brownian dynamics (BD) to capture better picture during phase separation and yielding mechanism in colloidal system with short-ranged attractive force. However, BD neglects multi-body hydrodynamic interactions (HI) which are believed to be responsible for the second yielding of colloidal gels. We envision using dissipative particle dynamics (DPD) with modified depletion potential and hydrodynamic interactions, as a coarse-grain model, can provide a robust simulation package to address the gel formation process and yielding in short ranged-attractive colloidal systems. The behavior of colloidal gels with different attraction potentials under flow is examined and structural fingerprints of yielding in these systems will be discussed.

  6. Mucosal effects of tenofovir 1% gel.

    PubMed

    Hladik, Florian; Burgener, Adam; Ballweber, Lamar; Gottardo, Raphael; Vojtech, Lucia; Fourati, Slim; Dai, James Y; Cameron, Mark J; Strobl, Johanna; Hughes, Sean M; Hoesley, Craig; Andrew, Philip; Johnson, Sherri; Piper, Jeanna; Friend, David R; Ball, T Blake; Cranston, Ross D; Mayer, Kenneth H; McElrath, M Juliana; McGowan, Ian

    2015-01-01

    Tenofovir gel is being evaluated for vaginal and rectal pre-exposure prophylaxis against HIV transmission. Because this is a new prevention strategy, we broadly assessed its effects on the mucosa. In MTN-007, a phase-1, randomized, double-blinded rectal microbicide trial, we used systems genomics/proteomics to determine the effect of tenofovir 1% gel, nonoxynol-9 2% gel, placebo gel or no treatment on rectal biopsies (15 subjects/arm). We also treated primary vaginal epithelial cells from four healthy women with tenofovir in vitro. After seven days of administration, tenofovir 1% gel had broad-ranging effects on the rectal mucosa, which were more pronounced than, but different from, those of the detergent nonoxynol-9. Tenofovir suppressed anti-inflammatory mediators, increased T cell densities, caused mitochondrial dysfunction, altered regulatory pathways of cell differentiation and survival, and stimulated epithelial cell proliferation. The breadth of mucosal changes induced by tenofovir indicates that its safety over longer-term topical use should be carefully monitored. PMID:25647729

  7. Continuum Models of Stimuli-responsive Gels

    NASA Astrophysics Data System (ADS)

    Hong, Wei

    Immersed in a solution of small molecules and ions, a network of long-chain polymers may imbibe the solution and swell, resulting in a polymeric gel. Depending on the molecular structure of the polymers, the amount of swelling can be regulated by moisture, mechanical forces, ionic strength, electric field, pH value, and many other types of stimuli. Starting from the basic principles of non-equilibrium thermodynamics, this chapter formulates a field theory of the coupled large deformation and mass transportation in a neutral polymeric gel. The theory is then extended to study polyelectrolyte gels with charge-carrying networks by accounting for the electromechanical coupling and migration of solute ions. While the theoretical framework is adaptable to various types of material models, some representative ones are described through specific free-energy functions and kinetic laws. A specific material law for pH-sensitive gels—a special type of polyelectrolyte gels—is introduced as an example of incorporating chemical reactions in modeling stimuli-responsive gels. Finally, a simplified theory for the equilibrium but inhomogeneous swelling of a polymeric gel is deduced. The theory and the specific material models are illustrated through several examples.

  8. Toward sol-gel-based sensors

    SciTech Connect

    Jordan, J.D.; Ingersoll, C.M.; Dunbar, R.A.

    1995-12-31

    Advances in biotechnology have produced a variety of antibodies and other biomolecules that possess selective recognition capabilities. Current techniques for the immobilization of these biomolecules typically involve multistep derivatization of a primary substrate, which is labor intensive and often requires large volumes of costly reagents. Further, these immobilization chemistries often adversely affect the characteristic properties of the protein (e.g., the binding affinity). As a result, the need for fast, accurate, inexpensive, and simple to operate diagnostic assays escalates. Because of their room temperature processing, transparency, inertness, and tunable pore structure, sol-gel-derived composites represent promising chemical and biosensing platforms. To date, many researchers have entrapped proteins and enzymes in sol-gel monoliths, and found that they retain some of their native properties. Our group first reported on the affinity of a sol-gel entrapped antibody. However, although these biogel monoliths were promising, analyte diffusion through the monolith matrix is slow, resulting in long response times. Thus, it is clear that the next level of sol-gel-derived biosensor must depend on thin film technology. In the current work, the affinity of fluorescein entrapped within a sol-gel derived thin film for the anti fluorescent hapten, 5- (and 6-)-carboxy 4{prime}, 5{prime}-dimethylfluorescein, is investigated. A novel film preparation technique will be introduced, and the response and response times of these films as a function of processing and storage conditions will be discussed.

  9. DNA DAMAGE QUANTITATION BY ALKALINE GEL ELECTROPHORESIS.

    SciTech Connect

    SUTHERLAND,B.M.; BENNETT,P.V.; SUTHERLAND, J.C.

    2004-03-24

    Physical and chemical agents in the environment, those used in clinical applications, or encountered during recreational exposures to sunlight, induce damages in DNA. Understanding the biological impact of these agents requires quantitation of the levels of such damages in laboratory test systems as well as in field or clinical samples. Alkaline gel electrophoresis provides a sensitive (down to {approx} a few lesions/5Mb), rapid method of direct quantitation of a wide variety of DNA damages in nanogram quantities of non-radioactive DNAs from laboratory, field, or clinical specimens, including higher plants and animals. This method stems from velocity sedimentation studies of DNA populations, and from the simple methods of agarose gel electrophoresis. Our laboratories have developed quantitative agarose gel methods, analytical descriptions of DNA migration during electrophoresis on agarose gels (1-6), and electronic imaging for accurate determinations of DNA mass (7-9). Although all these components improve sensitivity and throughput of large numbers of samples (7,8,10), a simple version using only standard molecular biology equipment allows routine analysis of DNA damages at moderate frequencies. We present here a description of the methods, as well as a brief description of the underlying principles, required for a simplified approach to quantitation of DNA damages by alkaline gel electrophoresis.

  10. Mucosal effects of tenofovir 1% gel

    PubMed Central

    Hladik, Florian; Burgener, Adam; Ballweber, Lamar; Gottardo, Raphael; Vojtech, Lucia; Fourati, Slim; Dai, James Y; Cameron, Mark J; Strobl, Johanna; Hughes, Sean M; Hoesley, Craig; Andrew, Philip; Johnson, Sherri; Piper, Jeanna; Friend, David R; Ball, T Blake; Cranston, Ross D; Mayer, Kenneth H; McElrath, M Juliana; McGowan, Ian

    2015-01-01

    Tenofovir gel is being evaluated for vaginal and rectal pre-exposure prophylaxis against HIV transmission. Because this is a new prevention strategy, we broadly assessed its effects on the mucosa. In MTN-007, a phase-1, randomized, double-blinded rectal microbicide trial, we used systems genomics/proteomics to determine the effect of tenofovir 1% gel, nonoxynol-9 2% gel, placebo gel or no treatment on rectal biopsies (15 subjects/arm). We also treated primary vaginal epithelial cells from four healthy women with tenofovir in vitro. After seven days of administration, tenofovir 1% gel had broad-ranging effects on the rectal mucosa, which were more pronounced than, but different from, those of the detergent nonoxynol-9. Tenofovir suppressed anti-inflammatory mediators, increased T cell densities, caused mitochondrial dysfunction, altered regulatory pathways of cell differentiation and survival, and stimulated epithelial cell proliferation. The breadth of mucosal changes induced by tenofovir indicates that its safety over longer-term topical use should be carefully monitored. Clinical trial registration: NCT01232803. DOI: http://dx.doi.org/10.7554/eLife.04525.001 PMID:25647729

  11. 34 CFR 668.163 - Maintaining and accounting for funds.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 34 Education 3 2012-07-01 2012-07-01 false Maintaining and accounting for funds. 668.163 Section... POSTSECONDARY EDUCATION, DEPARTMENT OF EDUCATION STUDENT ASSISTANCE GENERAL PROVISIONS Cash Management § 668.163 Maintaining and accounting for funds. (a)(1) Bank or investment account. An institution must maintain title...

  12. 34 CFR 668.163 - Maintaining and accounting for funds.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 34 Education 3 2010-07-01 2010-07-01 false Maintaining and accounting for funds. 668.163 Section... POSTSECONDARY EDUCATION, DEPARTMENT OF EDUCATION STUDENT ASSISTANCE GENERAL PROVISIONS Cash Management § 668.163 Maintaining and accounting for funds. (a)(1) Bank or investment account. An institution must maintain title...

  13. 34 CFR 668.163 - Maintaining and accounting for funds.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 34 Education 3 2011-07-01 2011-07-01 false Maintaining and accounting for funds. 668.163 Section... POSTSECONDARY EDUCATION, DEPARTMENT OF EDUCATION STUDENT ASSISTANCE GENERAL PROVISIONS Cash Management § 668.163 Maintaining and accounting for funds. (a)(1) Bank or investment account. An institution must maintain title...

  14. 34 CFR 668.163 - Maintaining and accounting for funds.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 34 Education 3 2014-07-01 2014-07-01 false Maintaining and accounting for funds. 668.163 Section... POSTSECONDARY EDUCATION, DEPARTMENT OF EDUCATION STUDENT ASSISTANCE GENERAL PROVISIONS Cash Management § 668.163 Maintaining and accounting for funds. (a)(1) Bank or investment account. An institution must maintain title...

  15. 34 CFR 668.163 - Maintaining and accounting for funds.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 34 Education 3 2013-07-01 2013-07-01 false Maintaining and accounting for funds. 668.163 Section... POSTSECONDARY EDUCATION, DEPARTMENT OF EDUCATION STUDENT ASSISTANCE GENERAL PROVISIONS Cash Management § 668.163 Maintaining and accounting for funds. (a)(1) Bank or investment account. An institution must maintain title...

  16. 10 CFR 1304.111 - Maintaining records of disclosures.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 4 2011-01-01 2011-01-01 false Maintaining records of disclosures. 1304.111 Section 1304.111 Energy NUCLEAR WASTE TECHNICAL REVIEW BOARD PRIVACY ACT OF 1974 § 1304.111 Maintaining records of disclosures. (a) The Board shall maintain a log containing the date, nature, and purpose of each disclosure...

  17. 10 CFR 1304.111 - Maintaining records of disclosures.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Maintaining records of disclosures. 1304.111 Section 1304.111 Energy NUCLEAR WASTE TECHNICAL REVIEW BOARD PRIVACY ACT OF 1974 § 1304.111 Maintaining records of disclosures. (a) The Board shall maintain a log containing the date, nature, and purpose of each disclosure...

  18. 10 CFR 1304.114 - Responsibility for maintaining adequate safeguards.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 4 2011-01-01 2011-01-01 false Responsibility for maintaining adequate safeguards. 1304.114 Section 1304.114 Energy NUCLEAR WASTE TECHNICAL REVIEW BOARD PRIVACY ACT OF 1974 § 1304.114 Responsibility for maintaining adequate safeguards. The Board has the responsibility for maintaining...

  19. 4 CFR 200.14 - Responsibility for maintaining adequate safeguards.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 4 Accounts 1 2010-01-01 2010-01-01 false Responsibility for maintaining adequate safeguards. 200.14 Section 200.14 Accounts RECOVERY ACCOUNTABILITY AND TRANSPARENCY BOARD PRIVACY ACT OF 1974 § 200.14 Responsibility for maintaining adequate safeguards. The Board has the responsibility for maintaining adequate technical, physical, and...

  20. 19 CFR 163.2 - Persons required to maintain records.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Persons required to maintain records. 163.2...; DEPARTMENT OF THE TREASURY (CONTINUED) RECORDKEEPING § 163.2 Persons required to maintain records. (a... maintain records and shall render such records for examination and inspection by Customs: (1) An...

  1. 10 CFR 1304.114 - Responsibility for maintaining adequate safeguards.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Responsibility for maintaining adequate safeguards. 1304.114 Section 1304.114 Energy NUCLEAR WASTE TECHNICAL REVIEW BOARD PRIVACY ACT OF 1974 § 1304.114 Responsibility for maintaining adequate safeguards. The Board has the responsibility for maintaining adequate technical, physical, and security...

  2. 40 CFR 62.14460 - What records must I maintain?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 8 2010-07-01 2010-07-01 false What records must I maintain? 62.14460 Section 62.14460 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS... Reporting and Recordkeeping Requirements § 62.14460 What records must I maintain? You must maintain...

  3. 10 CFR 1304.114 - Responsibility for maintaining adequate safeguards.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 4 2014-01-01 2014-01-01 false Responsibility for maintaining adequate safeguards. 1304.114 Section 1304.114 Energy NUCLEAR WASTE TECHNICAL REVIEW BOARD PRIVACY ACT OF 1974 § 1304.114 Responsibility for maintaining adequate safeguards. The Board has the responsibility for maintaining...

  4. 10 CFR 1304.114 - Responsibility for maintaining adequate safeguards.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 4 2012-01-01 2012-01-01 false Responsibility for maintaining adequate safeguards. 1304.114 Section 1304.114 Energy NUCLEAR WASTE TECHNICAL REVIEW BOARD PRIVACY ACT OF 1974 § 1304.114 Responsibility for maintaining adequate safeguards. The Board has the responsibility for maintaining adequate technical, physical, and security...

  5. 10 CFR 1304.111 - Maintaining records of disclosures.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 4 2013-01-01 2013-01-01 false Maintaining records of disclosures. 1304.111 Section 1304.111 Energy NUCLEAR WASTE TECHNICAL REVIEW BOARD PRIVACY ACT OF 1974 § 1304.111 Maintaining records of disclosures. (a) The Board shall maintain a log containing the date, nature, and purpose of each disclosure...

  6. 10 CFR 1304.114 - Responsibility for maintaining adequate safeguards.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 4 2013-01-01 2013-01-01 false Responsibility for maintaining adequate safeguards. 1304.114 Section 1304.114 Energy NUCLEAR WASTE TECHNICAL REVIEW BOARD PRIVACY ACT OF 1974 § 1304.114 Responsibility for maintaining adequate safeguards. The Board has the responsibility for maintaining...

  7. 10 CFR 1304.111 - Maintaining records of disclosures.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 4 2014-01-01 2014-01-01 false Maintaining records of disclosures. 1304.111 Section 1304.111 Energy NUCLEAR WASTE TECHNICAL REVIEW BOARD PRIVACY ACT OF 1974 § 1304.111 Maintaining records of disclosures. (a) The Board shall maintain a log containing the date, nature, and purpose of each disclosure...

  8. 10 CFR 1304.111 - Maintaining records of disclosures.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 4 2012-01-01 2012-01-01 false Maintaining records of disclosures. 1304.111 Section 1304.111 Energy NUCLEAR WASTE TECHNICAL REVIEW BOARD PRIVACY ACT OF 1974 § 1304.111 Maintaining records of disclosures. (a) The Board shall maintain a log containing the date, nature, and purpose of each disclosure of a record to any person or...

  9. 22 CFR 171.2 - Types of records maintained.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 22 Foreign Relations 1 2014-04-01 2014-04-01 false Types of records maintained. 171.2 Section 171.2 Foreign Relations DEPARTMENT OF STATE ACCESS TO INFORMATION AVAILABILITY OF INFORMATION AND RECORDS TO THE PUBLIC General Policy and Procedures § 171.2 Types of records maintained. Most of the records maintained by the Department pertain to...

  10. 4 CFR 200.14 - Responsibility for maintaining adequate safeguards.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 4 Accounts 1 2011-01-01 2011-01-01 false Responsibility for maintaining adequate safeguards. 200....14 Responsibility for maintaining adequate safeguards. The Board has the responsibility for maintaining adequate technical, physical, and security safeguards to prevent unauthorized disclosure...

  11. Metronidazole-containing gel for the treatment of periodontitis: an in vivo evaluation.

    PubMed

    Sato, Sandra; Fonseca, Maria José Vieira; Ciampo, José Orestes Del; Jabor, José Roberto; Pedrazzi, Vinícius

    2008-01-01

    The aim of this investigation was to monitor metronidazole concentrations in the gingival crevicular fluid (GCF) collected from periodontal pockets of dogs after treatment with an experimental 15% metronidazole gel. Five dogs had periodontitis induced by cotton ligatures placed subgingivally and maintained for a 30-day period. After the induction period, only pockets with 4 mm or deeper received the gel. Each pocket was filled up to the gingival margin by means of a syringe with a blunt-end needle. GCF was collected in paper strips and quantified in an electronic device before and after 15 minutes, 1 h, 6 h, 24 h and 48 h of gel administration. The GCF samples were assayed for metronidazole content by means of a high performance liquid chromatography method. Concentrations of metronidazole in the GCF of the 5 dogs (mean +/- SD, in microg/mL) were 0 +/- 0 before gel application and 47,185.75 +/- 24,874.35 after 15 minutes, 26,457.34 +/- 25,516.91 after 1 h, 24.18 +/- 23.11 after 6 h, 3.78 +/- 3.45 after 24 h and 3.34 +/- 5.54 after 48 h. A single administration of the 15% metronidazole gel released the drug in the GCF of dogs in levels several-fold higher than the minimum inhibitory concentration for some periodontopathogens grown in subgingival biofilms for up to one hour, but metronidazole could be detected in the GCF at least 48 hours after the gel application. PMID:18622484

  12. Hardening and yielding in colloidal gels

    NASA Astrophysics Data System (ADS)

    Del Gado, Emanuela; Colombo, Jader; Bouzid, Mehdi

    Attractive colloidal gel networks are disordered elastic solids that can form even in extremely dilute particle suspensions. With interaction strengths comparable to the thermal energy, their stress-bearing network can locally restructure via breaking and reforming inter-particle bonds. We use molecular dynamics simulations of a model system to investigate the strain hardening and the yielding process. During shear start up protocol, the system exhibits strong localization of tensile stresses that may be released through the breaking and formation of new bonds. In this regime, the small amplitude oscillatory shear analysis shows that the storage and the loss modulus follow a power law behavior that are closely reminiscent of experimental observations. At large accumulated strains, the strain-induced reorganization of the gel may trigger flow heterogeneities and eventually lead to the yielding of the gel via a quasi brittle damage of its structure.

  13. Modeling polymer gel that strengthen under tension

    NASA Astrophysics Data System (ADS)

    Biswas, Santidan; Yashin, Victor V.; Balazs, Anna C.

    We develop a constitutive model of a responsive polymer gel, which can reversibly form additional crosslinks when under tension. We assume that the polymer chains incorporate the folded domains encompassing the reactive functional groups (cryptic sites). Under extension of the network, the domains unfold and expose the cryptic sites, which can then form labile bonds with the linker chains grafted to the network. Once the deformation is removed, the linkers detach from the cryptic sites, and unfolded domains go back to the folded configuration thus hiding the cryptic sites. The gel behavior under applied force is described by the equations of elasticity of the polymer network coupled to the kinetic equations for the folding and binding transitions. The developed model could be used for designing new polymer gel-based materials that exhibit self-strengthening in response to a mechanical action.

  14. Gel-Filled Holders For Ultrasonic Transducers

    NASA Technical Reports Server (NTRS)

    Companion, John A.

    1992-01-01

    In new technique, ultrasonic transducer embedded in rubbery, castable, low-loss gel to enable transducer to "look" into surface of test object or human body at any desired angle. Composed of solution of water and ethylene glycol in collagen matrix. Provides total contact of water bath, also used on bodies or objects too large for water baths, even if moving. Also provides look angles of poly(methyl methacrylate) angle block with potential of reduced acoustic impedance and refraction. Custom-tailored to task at hand, and gel sufficiently inexpensive to be discarded upon completion. Easy to couple ultrasound in and out of gel, minimizing losses and artifacts of other types of standoffs employed in ultrasonic testing.

  15. On the scattering properties of polyelectrolyte gels

    NASA Astrophysics Data System (ADS)

    Barrat, Jean-Louis; Joanny, Jean-François; Pincus, Phil

    1992-08-01

    We present a simple model for scattering properties of polyelectrolyte gels at swelling equilibrium. In the weak screening limit where the Debye-Hückel screening length is larger than the mesh size of the gel, the direct electrostatic interactions are negligible and the swelling is driven by the osmotic pressure of the counterions. The tension created by this pressure is transmitted through the crosslinks to the elastic chains which behave as isolated chains with an applied force at their end points. The structure factor of the gel can be split into a frozen component due to the average concentration heterogeneities and a thermodynamic component due to concentration fluctuations. The frozen component has a peak at a wavevector of the order of the mesh size of the gel, the thermodynamic component has a peak at a higher wavevector of the order of the inverse transverse radius of the chains. At infinite times the dynamic structure factor relaxes towards the frozen component of the static structure factor. In the limit of small wavevectors the relaxation is diffusive with a diffusion constant equal to the Stokes diffusion constant of the Pincus blobs of the stretched chains. The diffusion constant shows a minimum at a wavevector of the order of the inverse transverse radius of the chains. Nous présentons un modèle simple pour étudier la diffusion de rayonnement par des gels polylectrolytes à l'équilibre de gonflement. Dans la limite d'écrantage faible où la longueur d'écran de Debye-Hückel est plus grande que la maille du gel, les interactions électrostatiques directes sont négligeables et le gonflement est dû à la pression osmotique des contreions. La tension créée par cette pression est transmise par les noeuds du gel aux chaines élastiques qui se comportent comme des chaines isolées avec une force extérieure appliquée aux extrémités. Le facteur de structure du gel est la somme d'une composante gelée due aux hétérogénéités de concentration

  16. Writing in the granular gel medium

    PubMed Central

    Bhattacharjee, Tapomoy; Zehnder, Steven M.; Rowe, Kyle G.; Jain, Suhani; Nixon, Ryan M.; Sawyer, W. Gregory; Angelini, Thomas E.

    2015-01-01

    Gels made from soft microscale particles smoothly transition between the fluid and solid states, making them an ideal medium in which to create macroscopic structures with microscopic precision. While tracing out spatial paths with an injection tip, the granular gel fluidizes at the point of injection and then rapidly solidifies, trapping injected material in place. This physical approach to creating three-dimensional (3D) structures negates the effects of surface tension, gravity, and particle diffusion, allowing a limitless breadth of materials to be written. With this method, we used silicones, hydrogels, colloids, and living cells to create complex large aspect ratio 3D objects, thin closed shells, and hierarchically branched tubular networks. We crosslinked polymeric materials and removed them from the granular gel, whereas uncrosslinked particulate systems were left supported within the medium for long times. This approach can be immediately used in diverse areas, contributing to tissue engineering, flexible electronics, particle engineering, smart materials, and encapsulation technologies. PMID:26601274

  17. Preparation and characterization of hydrophobic superparamagnetic gel.

    SciTech Connect

    Liu, X.; Kaminski, M. D.; Guan, Y.; Chen, H.; Liu, H.; Rosengart, A. J.; Chemical Engineering; Univ. of Chicago; Pritzker School of Medicine; Chinese Academy of Sciences

    2006-01-01

    The present study describes the preparation and analysis of a highly concentrated hydrophobic oleic acid-coated magnetite gel. By contrast to conventional techniques to prepare magnetic fluids, herein the oleic acid was introduced as a reactant during the initial crystallization phase of magnetite that was obtained by the co-precipitation of Fe(II) and Fe(III) salts by addition of ammonium hydroxide. The resulting gelatinous hydrophobic magnetite was characterized in terms of morphology, particle size, magnetic properties, crystal structure, and hydrophobicity/hydrophilicity. This magnetic gel exhibited superparamagnetism with a saturation magnetization of 46.0 emu/g at room temperature and could be well dispersed both in polar and nonpolar carrier liquids. This protocol produced highly concentrated hydrophobic magnetic gel for biopolymer encapsulations.

  18. Characterizing tunable dynamics in an active gel

    NASA Astrophysics Data System (ADS)

    Henkin, Gil; Decamp, Stephen; Chen, Daniel; Dogic, Zvonimir

    2014-03-01

    We experimentally investigate dynamics of an active gel of bundled microtubules that is driven to far-from-equilibrium steady states by clusters of kinesin molecular motors. Upon the addition of ATP, the coordinated action of thousands of molecular motors drives this gel to an active, percolating state that persists for hours and is only limited by the stability of constituent proteins and the availability of the chemical fuel ATP. We extensively characterize how enhanced transport in emergent macroscopic flows depends on relevant molecular parameters, including ATP, motor, and depletant concentrations, microtubule concentration and length, as well as structure of the motor clusters. Our results show that the properties and dynamics of this active isotropic gel are highly tunable, suggesting that this is an ideal system for studying the behavior of active materials.

  19. Writing in the granular gel medium.

    PubMed

    Bhattacharjee, Tapomoy; Zehnder, Steven M; Rowe, Kyle G; Jain, Suhani; Nixon, Ryan M; Sawyer, W Gregory; Angelini, Thomas E

    2015-09-01

    Gels made from soft microscale particles smoothly transition between the fluid and solid states, making them an ideal medium in which to create macroscopic structures with microscopic precision. While tracing out spatial paths with an injection tip, the granular gel fluidizes at the point of injection and then rapidly solidifies, trapping injected material in place. This physical approach to creating three-dimensional (3D) structures negates the effects of surface tension, gravity, and particle diffusion, allowing a limitless breadth of materials to be written. With this method, we used silicones, hydrogels, colloids, and living cells to create complex large aspect ratio 3D objects, thin closed shells, and hierarchically branched tubular networks. We crosslinked polymeric materials and removed them from the granular gel, whereas uncrosslinked particulate systems were left supported within the medium for long times. This approach can be immediately used in diverse areas, contributing to tissue engineering, flexible electronics, particle engineering, smart materials, and encapsulation technologies. PMID:26601274

  20. Reduction of gas and water permeabilities using gels

    SciTech Connect

    Seright, R.S.

    1995-05-01

    The authors investigated how different types of gels reduce permeability to water and gases in porous rock. Five types of gels were studied, including (1) a ``weak`` resorcinol-formaldehyde gel, (2) a ``strong`` resorcinol-formaldehyde gel, (3) a Cr(III)-xanthan gel, (4) a Cr(III)-acetate-HPAM gel, and (5) a colloidal-silica gel. For all gels, extensive coreflood experiments were performed to assess the permeability-reduction characteristics and the stability to repeated water-alternating-gas (WAG) cycles. Studies were performed at pressures up to 1,500 psi using either nitrogen or carbon dioxide as the compressed gas. They developed a coreflood apparatus with an inline high-pressure spectrophotometer that allowed tracer studies to be performed without depressurizing the core. They noted several analogies between the results reported here and those observed during a parallel study of the effects of gel on oil and water permeabilities.

  1. Pouring and running a protein gel by reusing commercial cassettes.

    PubMed

    Hwang, Alexander C; Grey, Paris H; Cuddy, Katrina; Oppenheimer, David G

    2012-01-01

    The evaluation of proteins using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis is a common technique used by biochemistry and molecular biology researchers. For laboratories that perform daily analyses of proteins, the cost of commercially available polyacrylamide gels (~$10/gel) can be considerable over time. To mitigate this cost, some researchers prepare their own polyacrylamide gels. Traditional methods of pouring these gels typically utilize specialized equipment and glass gel plates that can be expensive and preclude pouring many gels and storing them for future use. Furthermore, handling of glass plates during cleaning or gel pouring can result in accidental breakage creating a safety hazard, which may preclude their use in undergraduate laboratory classes. Our protocol demonstrates how to pour multiple protein gels simultaneously by recycling Invitrogen Nupage Novex minigel cassettes, and inexpensive materials purchased at a home improvement store. This economical and streamlined method includes a way to store the gels at 4°C for a few weeks. By re-using the plastic gel cassettes from commercially available gels, labs that run frequent protein gels can save significant costs and help the environment. In addition, plastic gel cassettes are extremely resistant to breakage, which makes them ideal for undergraduate laboratory classrooms. PMID:22349047

  2. Dynamic Light Scattering From Colloidal Gels

    NASA Technical Reports Server (NTRS)

    Krall, A. H.; Weitz, David A.

    1996-01-01

    We present a brief, preliminary account of the interpretation of dynamic light scattering from fractal colloidal gels. For small scattering angles, and for high initial colloid particle volume fractions, the correlation functions exhibit arrested decay, reflecting the non-ergodic nature of these systems and allowing us to directly determine the elastic modulus of the gels. For smaller initial volume fractions, the correlation functions decay completely. In all cases, the initial decay is not exponential, but is instead described by a stretched exponential. We summarize the principles of a model that accounts for these data and discuss the scaling behavior of the measured parameters.

  3. Neutron detector using sol-gel absorber

    SciTech Connect

    Hiller, J.M.; Wallace, S.A.; Dai, S.

    1999-10-26

    An neutron detector composed of fissionable material having ions of lithium, uranium, thorium, plutonium, or neptunium, contained within a glass film fabricated using a sol-gel method combined with a particle detector is disclosed. When the glass film is bombarded with neutrons, the fissionable material emits fission particles and electrons. Prompt emitting activated elements yielding a high energy electron contained within a sol-gel glass film in combination with a particle detector is also disclosed. The emissions resulting from neutron bombardment can then be detected using standard UV and particle detection methods well known in the art, such as microchannel plates, channeltrons, and silicon avalanche photodiodes.

  4. Neutron detector using sol-gel absorber

    DOEpatents

    Hiller, John M.; Wallace, Steven A.; Dai, Sheng

    1999-01-01

    An neutron detector composed of fissionable material having ions of lithium, uranium, thorium, plutonium, or neptunium, contained within a glass film fabricated using a sol-gel method combined with a particle detector is disclosed. When the glass film is bombarded with neutrons, the fissionable material emits fission particles and electrons. Prompt emitting activated elements yielding a high energy electron contained within a sol-gel glass film in combination with a particle detector is also disclosed. The emissions resulting from neutron bombardment can then be detected using standard UV and particle detection methods well known in the art, such as microchannel plates, channeltrons, and silicon avalanche photodiodes.

  5. Hybrid sol-gel optical materials

    DOEpatents

    Zeigler, J.M.

    1993-04-20

    Hybrid sol-gel materials comprise silicate sols cross-linked with linear polysilane, polygermane, or poly(silane-germane). The sol-gel materials are useful as optical identifiers in tagging and verification applications and, in a different aspect, as stable, visible light transparent non-linear optical materials. Methyl or phenyl silicones, polyaryl sulfides, polyaryl ethers, and rubbery polysilanes may be used in addition to the linear polysilane. The linear polymers cross-link with the sol to form a matrix having high optical transparency, resistance to thermooxidative aging, adherence to a variety of substrates, brittleness, and a resistance to cracking during thermal cycling.

  6. Hybrid sol-gel optical materials

    DOEpatents

    Zeigler, John M.

    1993-01-01

    Hybrid sol-gel materials comprise silicate sols cross-linked with linear polysilane, polygermane, or poly(silane-germane). The sol-gel materials are useful as optical identifiers in tagging and verification applications and, in a different aspect, as stable, visible light transparent non-linear optical materials. Methyl or phenyl silicones, polyaryl sulfides, polyaryl ethers, and rubbery polysilanes may be used in addition to the linear polysilane. The linear polymers cross-link with the sol to form a matrix having high optical transparency, resistance to thermooxidative aging, adherence to a variety of substrates, brittleness, and a resistance to cracking during thermal cycling.

  7. Hybrid sol-gel optical materials

    DOEpatents

    Zeigler, John M.

    1992-01-01

    Hybrid sol-gel materials comprise silicate sols cross-linked with linear polysilane, polygermane, or poly(silane-germane). The sol-gel materials are useful as optical identifiers in tagging and verification applications and, in a different aspect, as stable, visible light transparent non-linear optical materials. Methyl or phenyl silicones, polyaryl sulfides, polyaryl ethers, and rubbery polysilanes may be used in addition to the linear polysilane. The linear polymers cross-link with the sol to form a matrix having high optical transparency, resistance to thermooxidative aging, adherence to a variety of substrates, brittleness, and a resistance to cracking during thermal cycling.

  8. Alignment and nonlinear elasticity in biopolymer gels

    NASA Astrophysics Data System (ADS)

    Feng, Jingchen; Levine, Herbert; Mao, Xiaoming; Sander, Leonard M.

    2015-04-01

    We present a Landau-type theory for the nonlinear elasticity of biopolymer gels with a part of the order parameter describing induced nematic order of fibers in the gel. We attribute the nonlinear elastic behavior of these materials to fiber alignment induced by strain. We suggest an application to contact guidance of cell motility in tissue. We compare our theory to simulation of a disordered lattice model for biopolymers. We treat homogeneous deformations such as simple shear, hydrostatic expansion, and simple extension, and obtain good agreement between theory and simulation. We also consider a localized perturbation which is a simple model for a contracting cell in a medium.

  9. Electroactive polymer gels based on epoxy resin

    NASA Astrophysics Data System (ADS)

    Samui, A. B.; Jayakumar, S.; Jayalakshmi, C. G.; Pandey, K.; Sivaraman, P.

    2007-04-01

    Five types of epoxy gels have been synthesized from common epoxy resins and hardeners. Fumed silica and nanoclay, respectively, were used as fillers and butyl methacrylate/acrylamide were used as monomer(s) for making interpenetrating polymer networks (IPNs) in three compositions. Swelling study, tensile property evaluation, dynamic mechanical thermal analysis, thermo-gravimetric analysis, scanning electron microscopy and electroactive property evaluation were done. The gels have sufficient mechanical strength and the time taken for bending to 20° was found to be 22 min for forward bias whereas it was just 12 min for reverse bias.

  10. Simple cloud chambers using gel ice packs

    NASA Astrophysics Data System (ADS)

    Kamata, Masahiro; Kubota, Miki

    2012-07-01

    Although cloud chambers are highly regarded as teaching aids for radiation education, school teachers have difficulty in using cloud chambers because they have to prepare dry ice or liquid nitrogen before the experiment. We developed a very simple and inexpensive cloud chamber that uses the contents of gel ice packs which can substitute for dry ice or liquid nitrogen. The gel can be frozen in normal domestic freezers, and can be used repeatedly by re-freezing. The tracks of alpha-ray particles can be observed continuously for about 20 min, and the operation is simple and easy.

  11. Aggregation-structure-elasticity relationship of gels

    NASA Astrophysics Data System (ADS)

    Ma, Hang-Shing

    Aerogel is a mesoporous, low-density material which is desirable for applications like thermal insulation and low-k interlayer dielectric. However, its lack of mechanical integrity hinders its development. Experiments have shown that aerogels exhibit a scaling relationship E ∝ rho m between modulus E and density rho, with the exponent m usually between 3 and 4. The objective of the dissertation is to use computer modeling to understand how the random aggregation process accounts for the fractal structure and the compliant nature of aerogels. Model gels were created by the diffusion-limited cluster-cluster aggregation (DLCA), which simulates random aggregation leading to the sol-gel transition. Then each resulting structure was modeled as an elastic beam network and numerically compressed using the finite element method (FEM). Analyses showed that the DLCA gels reproduced the scaling relationship after trimming the non-contributive dangling branches from the mechanically efficient looped networks. The dangling bond deflection (DEF) model was therefore developed to model the random rotational movement of the dangling branches and the subsequent loop structure formation. Model gels with extensive loops and negligible dangling branches were simulated by combining the DLCA and DEF models. Representation of the aerogel networks by the DLCADEF models was validated for the resemblance of the fractal geometry and elastic behavior. The lack of mechanical integrity in aerogels is a natural consequence of the random aggregation and the resulting fractal structure. Fractal clusters are created in the early stage of aggregation, each of which is characterized by a dense core and sparse perimeter. These clusters grow in size until they percolate at the gel point by knitting together at the perimeters. The gel structure possesses a "blob-and-link" architecture, with the blobs representing the rigid cores of the fractal clusters, and the links corresponding to the tenuous chains

  12. 2% Lidocaine gel or plain lubricating gel: Which one should be used in male flexible cystoscopy?

    PubMed Central

    Akkoç, Ali; Kartalmış, Mahir; Aydın, Cemil; Topaktaş, Ramazan; Altın, Selçuk; Aykaç, Aykut

    2016-01-01

    Objective To investigate and compare the effects on pain of intraurethral 2% lidocaine gel and plain lubricating gel in male patients underwent flexible cystoscopy. Material and methods The data of 220 male patients who underwent flexible cystoscopy between March 2012 and August 2014 were retrospectively analized. The patients were divided into 2 groups according to using intraurethral gel types. Group I included 120 patients who were underwent flexible cystoscopy with 2% lidocaine gel and Group II was consisted from 100 patients who underwent flexible cystoscopy with plain lubricating gel. The groups were compared according to postprocedure data including pain score, procedure time and age of patients. Results The mean age of the patients in Group I was 50.02±11.87 years while that in Group II was 52.03±13.37 years (p=0.492). The mean procedure times were 6.02±0.787 and 6.28±0.689 minutes in Group I and Group II respectively (p=0.061). Pain perception scores were not statistically different between the groups (Group I: 3.10±0.980, Group II: 3.34±0.789, p=0.132). Conclusion Use of intraurethral 2% lidocaine gel has no advantage over plain lubricating gel in regard to pain control during flexible cystoscopy in men. PMID:27274894

  13. Gel-expanded to gel-condensed transition in neurofilament networks revealed by direct force measurements

    NASA Astrophysics Data System (ADS)

    Beck, Roy; Deek, Joanna; Jones, Jayna B.; Safinya, Cyrus R.

    2010-01-01

    Neurofilaments (NF)-the principal cytoskeletal constituent of myelinated axons in vertebrates-consist of three molecular-weight subunit proteins NF-L (low), NF-M (medium) and NF-H (high), assembled to form mature filaments with protruding unstructured C-terminus side arms. Liquid-crystal gel networks of side-arm-mediated neurofilament assemblies have a key role in the mechanical stability of neuronal processes. Disruptions of the neurofilament network, owing to neurofilament over-accumulation or incorrect side-arm interactions, are a hallmark of motor-neuron diseases including amyotrophic lateral sclerosis. Using synchrotron X-ray scattering, we report on a direct measurement of forces in reconstituted neurofilament gels under osmotic pressure (P). With increasing pressure near physiological salt and average phosphorylation conditions, NF-LMH, comprising the three subunits near in vivo composition, or NF-LH gels, undergo for P>Pc~10kPa, an abrupt non-reversible gel-expanded to gel-condensed transition. The transition indicates side-arm-mediated attractions between neurofilaments consistent with an electrostatic model of interpenetrating chains. In contrast, NF-LM gels remain in a collapsed state for Pgel-condensed state at P>Pc. These findings, which delineate the distinct roles of NF-M and NF-H in regulating neurofilament interactions, shed light on possible mechanisms for disruptions of optimal mechanical network properties.

  14. Effect of gel matrix confinement on the solvent dynamics in supramolecular gels.

    PubMed

    Kowalczuk, Joanna; Rachocki, Adam; Bielejewski, Michał; Tritt-Goc, Jadwiga

    2016-06-15

    Supramolecular gels formed by the sugar gelator of methyl-4,6-O-(p-nitrobenzylidene)-α-d-glucopyranoside (1) with 1,3-propanediol (PG) and 1-butanol (BU) were prepared with different gelator concentrations. The solvent dynamics within gels, characterized by the diffusion coefficient (D) and the spin-lattice relaxation time (T1), was the subject of NMR diffusometry and relaxometry studies. The diffusion was studied as a function of diffusion time and gelator concentrations. The relaxation time was measured as a function of Larmor frequency. The decrease of the diffusion coefficient was observed as a function of diffusion time for both gels and for all studied gelator concentrations. It is indicative of the confinement effect due to the geometrical restrictions of the gel matrix. The relaxation data for PG solvent confined in 1/PG gel revealed the low frequency dispersion (in kHz region) which is a fingerprint of a specific interaction experienced by PG solvents in the presence of the rigid structure of gelator 1 aggregates. The relaxation model, well known from the interpretation of liquid confined in nanopores as reorientations mediated by translational displacements (RMTD), was successfully applied to analyze the data of studied solvents confined in matrices of supramolecular gels. The microstructures of gel matrices were imaged by Polarized Microscopy. PMID:27003500

  15. Free forming of the gel by 3D gel printer SWIM-ER

    NASA Astrophysics Data System (ADS)

    Okada, Koji; Tase, Taishi; Saito, Azusa; Makino, Masato; Gong, Jin; Kawakami, Masaru; Furukawa, Hidemitsu

    2015-04-01

    Gels, soft and wet materials, have unique properties such as material permeability, biocompatibility and low friction, which are hardly found in hard and dry materials. These superior characteristics of hydrogels promise to expand the medical applications. In recent years, the optical 3D gel printer named SWIM-ER (Soft and Wet Industrial - Easy Realizer) was developed by our team in order to fabricate tough gels with free form. We are aiming to create artificial blood vessel of the gel material by 3D gel printer. Artificial blood vessel is expected to be used for vascular surgery practice. The artificial blood vessel made by 3D gel printer can be create to free form on the basis of the biological data of the patient. Therefore, we believe it is possible to contribute to increasing the success rate and safety of vascular surgery by creating artificial blood vessel with 3D gel printer. The modeling method of SWIM-ER is as follow. Pregel solution is polymerized by one-point UV irradiation with optical fiber. The irradiation area is controlled by computer program, so that exact 3D free forming is realized. In this study, synthesis conditions are re-examined in order to improve the degree of freedom of fabrication. The dimensional accuracy in height direction is improved by increasing the cross linker concentration. We examined the relationship of resolution to the pitch and UV irradiation time in order to improve the modeling accuracy.

  16. Protein electrophoretic migration data from custom and commercial gradient gels.

    PubMed

    Miller, Andrew J; Roman, Brandon; Norstrom, Eric M

    2016-12-01

    This paper presents data related to the article "A method for easily customizable gradient gel electrophoresis" (A.J. Miller, B. Roman, E.M. Norstrom, 2016) [1]. Data is presented on the rate of electrophoretic migration of proteins in both hand-poured and commercially acquired acrylamide gradient gels. For each gel, migration of 9 polypeptides of various masses was measured upon completion of gel electrophoresis. Data are presented on the migration of proteins within separate lanes of the same gel as well as migration rates from multiple gels. PMID:27622203

  17. Multicolored, Low-Power, Flexible Electrochromic Devices Based on Ion Gels.

    PubMed

    Moon, Hong Chul; Kim, Chang-Hyun; Lodge, Timothy P; Frisbie, C Daniel

    2016-03-01

    Ion gels composed of a copolymer and a room temperature ionic liquid are versatile solid-state electrolytes with excellent features including high ionic conductivity, nonvolatility, easily tunable mechanical properties, good flexibility and solution processability. Ion gels can be functionalized by incorporating redox-active species such as electrochemiluminescent (ECL) luminophores or electrochromic (EC) dyes. Here, we enhance the functionality of EC gels for realizing multicolored EC devices (ECDs), either by controlling the chemical equilibrium between a monomer and dimer of a colored EC species, or by modifying the molecular structures of the EC species. All devices in this work are conveniently fabricated by a "cut-and-stick" strategy, and require very low power for maintaining the colored state [i.e., 90 μW/cm(2) (113 μA/cm(2) at -0.8 V) for blue, 4 μW/cm(2) (10 μA/cm(2) at -0.4 V) for green, and 32 μW/cm(2) (79 μA/cm(2) at -0.4 V) for red ECD]. We also successfully demonstrate a patterned, multicolored, flexible ECD on plastic. Overall, these results suggest that gel-based ECDs have significant potential as low power displays in printed electronics powered by thin-film batteries. PMID:26867428

  18. A heparin-mimicking reverse thermal gel for controlled delivery of positively charged proteins.

    PubMed

    Peña, Brisa; Shandas, Robin; Park, Daewon

    2015-06-01

    Positively charged therapeutic proteins have been used extensively for biomedical applications. However, the safety and efficacy of proteins are mostly limited by their physical and chemical instability and short half-lives in physiological conditions. To this end, we created a heparin-mimicking sulfonated reverse thermal gel as a novel protein delivery system by sulfonation of a graft copolymer, poly(serinol hexamethylene urea)-co-poly(N-isopropylacylamide), or PSHU-NIPAAm. The net charge of the sulfonated PSHU-NIPAAm was negative due to the presence of sulfonate groups. The sulfonated PSHU-NIPAAm showed a typical temperature-dependent sol-gel phase transition, where polymer solutions turned to a physical gel at around 32°C and maintained gel status at body temperature. Both in vitro cytotoxicity tests using C2C12 myoblast cells and in vivo cytotoxicity tests by subcutaneous injections demonstrated excellent biocompatibility. In vitro release tests using bovine serum albumin revealed that the release from the sulfonated PSHU-NIPAAm was more sustained than that from the plain PSHU-NIPAAm. Furthermore, this sulfonated PSHU-NIPAAm system did not affect protein structure after 70-day observation periods. PMID:25294242

  19. A heparin-mimicking reverse thermal gel for controlled delivery of positively charged proteins

    PubMed Central

    Peña, Brisa; Shandas, Robin; Park, Daewon

    2014-01-01

    Positively charged therapeutic proteins have been used extensively for biomedical applications. However, the safety and efficacy of proteins are mostly limited by their physical and chemical instability and short half-lives in physiological conditions. To this end, we created a heparin-mimicking sulfonated reverse thermal gel as a novel protein delivery system by sulfonation of a graft copolymer, poly(serinol hexamethylene urea)-co-poly(N-isopropylacylamide), or PSHU-NIPAAm. The net charge of the sulfonated PSHU-NIPAAm was negative due to the presence of sulfonate groups. The sulfonated PSHU-NIPAAm showed a typical temperature-dependent sol-gel phase transition, where polymer solutions turned to a physical gel at around 32°C and maintained gel status at body temperature. Both in vitro cytotoxicity tests using C2C12 myoblast cells and in vivo cytotoxicity tests by subcutaneous injections demonstrated excellent biocompatibility. In vitro release tests using bovine serum albumin (BSA) revealed that the release from the sulfonated PSHU-NIPAAm was more sustained than that from the plain PSHU-NIPAAm. Furthermore, this sulfonated PSHU-NIPAAm system did not affect protein structure after 70-day observation periods. PMID:25294242

  20. Characterizing the Effects of Heparin Gel Stiffness on Function of Primary Hepatocytes

    PubMed Central

    You, Jungmok; Park, Su-A; Shin, Dong-Sik; Patel, Dipali; Raghunathan, Vijay Krishna; Kim, Mihye; Murphy, Christopher J; Tae, Giyoong

    2013-01-01

    In the liver, hepatocytes are exposed to a large array of stimuli that shape hepatic phenotype. This in vivo microenvironment is lost when hepatocytes are cultured in standard cell cultureware, making it challenging to maintain hepatocyte function in vitro. Our article focused on one of the least studied inducers of the hepatic phenotype—the mechanical properties of the underlying substrate. Gel layers comprised of thiolated heparin (Hep-SH) and diacrylated poly(ethylene glycol) (PEG-DA) were formed on glass substrates via a radical mediated thiol–ene coupling reaction. The substrate stiffness varied from 10 to 110 kPa by changing the concentration of the precursor solution. ELISA analysis revealed that after 5 days, hepatocytes cultured on a softer heparin gel were synthesizing five times higher levels of albumin compared to those on a stiffer heparin gel. Immunofluorescent staining for hepatic markers, albumin and E-cadherin, confirmed that softer gels promoted better maintenance of the hepatic phenotype. Our findings point to the importance of substrate mechanical properties on hepatocyte function. PMID:23815179

  1. Effects of a Novel Dental Gel on Plaque and Gingivitis: A Comparative Study

    PubMed Central

    Dadkhah, M; Chung, NE; Ajdaharian, J; Wink, C; Klokkevold, P; Wilder-Smith, P

    2015-01-01

    Objectives The goal of this prospective, randomized, controlled, double-blinded study was to evaluate the effects of a novel dental gel on plaque and gingival health. The dental gel was designed to (1) break up and prevent re-accumulation of microbial biofilm, and (2) inhibit metal mediated inflammation. Materials and Methods Twenty-five subjects with moderate gingival inflammation (Löe and Silness Gingival Index ≥2) and pocket depths <4 were randomly assigned to brush twice daily for 21 days with the test or the control dental gel. On Days 0, 7, 14 and 21, plaque levels (Quigley-Hein, Turesky Modification Plaque Index), gingival inflammation (Löe and Silness Gingival Index) and gingival bleeding (modified Sulcus Bleeding Index) were determined by one blinded, investigator using a pressure sensitive probe. Results After 3 weeks, all 3 clinical indices were significantly improved in both groups (P<0.05) and significantly lower in the test group (P<0.05). Conclusion The novel dental gel formulation was provided effective plaque control and reduced gingival inflammation. Clinical Relevance A novel dentifrice formulation may be an effective tool for plaque removal and maintaining gingival health. PMID:26052472

  2. Mechanical properties and morphology of polymer gels

    NASA Astrophysics Data System (ADS)

    Sliozberg, Yelena; Sirk, Timothy; Brennan, John; Andzelm, Jan; Mrozek, Randy; Lenhart, Joseph

    2012-02-01

    Understanding morphology and mechanical response of polymeric gels is of particular importance to design materials with required energy dissipation characteristics. We will present our latest results for polymer gels based on 1) self-assembled block copolymers and 2) chemically cross-linked polymers. The dissipative particle dynamics (DPD) was used to predict morphology in good agreement with atomic force microscopy. We have performed DPD non-equilibrium oscillatory shear calculations predicting elastic modulus of unentangled gels that correlates well with experimental rheology data. However, this methodology fails to predict mechanics of entangled polymer networks due to unphysical chain crossing brought by the soft potentials used in DPD simulations. Recently, we have introduced an improved segmental repulsion potential that removes the bond crossing allowing for reptation dynamics. The improved DPD method was used in simulations for entangled gels to explore impact of branched architecture of solvent on the mechanical response to the tensile deformation. Novel architectures of solvent resulting in a dramatic increase of the elastic modulus were identified. The topological analysis was applied to understand contributions of chemical cross-links and entanglements to the stress.

  3. Ionic Conduction Mechanism of Polymer Gel Electrolytes

    NASA Astrophysics Data System (ADS)

    Saito, Yuria; Kataoka, Hiroshi

    2002-12-01

    Carrier migration mechanism of polymer gel electrolyte for lithium secondary batteries was investigated through the dynamic behavior of diffusion coefficient and conductivity. The gel prepared with PEO showed a homogeneous structure with any fraction of the electrolyte solution. The diffusion coefficient of the ionic species decreased with the increase in the polymer fraction in the gel. Cation migration is closely associated with the polymer, showing the reduced activation energy for diffusion with polymer in contrast to the increasing feature of the activation energy of the anion diffusion. The PVDF-gel electrolytes have a solid solubility limit due to the swelling saturation. The excess solution was then trapped in the cavities of the swollen polymer network. As a result, the diffusion showed two components. One is the fast migration of the carriers similar to that in the solution and the other is the relatively slow migration in the swollen region. The latter was influenced by the polymer due to the physical blocking and chemical interactive effects.

  4. Gel injection successfully shuts off excess water

    SciTech Connect

    1995-11-01

    Unocal applied a high-temperature organic polymer gel in Feather field Well H-43 in the UK North Sea to reduce water production in them more-permeable upper perforated section of the Brent Sand. The operation and technical details of the polymer system developed by Unocal, and how it was applied, are described in paper SPE 30426, ``Water shut off in the North Sea; Testing a new polymer system in the Heather field, UKCS Block 2/5.`` The authors concluded that the new gel system successfully isolated the Upper Brent water production, increasing oil production and decreasing water production. Lower perforations were successfully isolated using sized calcium carbonate suspended in an HEC polymer--a technique difficult to monitor in the deviated well. Batch mixing provided ``excellent`` quality gel, closely matching lab measured performance. And the gel required no pre-cooling in the near-wellbore area. Some 1,100 bbl were injected without excessive wellhead pressure, at 1 bpm. A summary of the paper`s highlights is presented here.

  5. Gel Permeation Chromatography of Fluoroether Polymers

    NASA Technical Reports Server (NTRS)

    Korus, Roger A.; Rosser, Robert W.

    1978-01-01

    A Method is described for determining the molecular weight distribution of fluorinated polymers by gel permeation chromatography. Porous silica-packed columns are used with Freon 113 as the chromatographic solvent. Fluoroether oligomers are used for column calibration in the molecular weight range of 1400 to 12000.

  6. Gel Filtration Chromatography: A Laboratory Experiment.

    ERIC Educational Resources Information Center

    Hurlbut, Jeffrey A.; Schonbeck, Niels D.

    1984-01-01

    Describes a rapid, visual demonstration of protein separation by gel filtration chromatography. The procedure separates two highly colored proteins of different molecular weights on a Sephadex G-75 in 45 minutes. This time includes packing the column as well. Background information, reagents needed, procedures used, and results obtained are…

  7. Aloe vera leaf gel: a review update.

    PubMed

    Reynolds, T; Dweck, A C

    1999-12-15

    Research since the 1986 review has largely upheld the therapeutic claims made in the earlier papers and indeed extended them into other areas. Treatment of inflammation is still the key effect for most types of healing but it is now realized that this is a complex process and that many of its constituent processes may be addressed in different ways by different gel components. A common theme running though much recent research is the immunomodulatory properties of the gel polysaccharides, especially the acetylated mannans from Aloe vera, which are now a proprietary substance covered by many patents. There have also been, however, persistent reports of active glycoprotein fractions from both Aloe vera and Aloe arborescens. There are also cautionary investigations warning of possible allergic effects on some patients. Reports also describe antidiabetic, anticancer and antibiotic activities, so we may expect to see a widening use of aloe gel. Several reputable suppliers produce a stabilized aloe gel for use as itself or in formulations and there may be moves towards isolating and eventually providing verified active ingredients in dosable quantities PMID:10624859

  8. Gel bead composition for metal adsorption

    SciTech Connect

    Scott, Charles D.; Woodward, Charlene A.; Byers, Charles H.

    1991-01-01

    The invention is a gel bead comprising propylene glycol alginate and bone gelatin and is capable of removing metals such as Sr and Cs from solution without adding other adsorbents. The invention could have application to the nuclear industry's waste removal activities.

  9. Gel bead composition for metal adsorption

    DOEpatents

    Scott, Charles D.; Woodward, Charlene A.; Byers, Charles H.

    1990-01-01

    The invention is a gel bead comprising propylene glycol alginate and bone gelatin and is capable of removing metals such as Sr and Cs from solution without adding other adsorbents. The invention could have application to the nuclear industry's waste removal activities.

  10. Simple Cloud Chambers Using Gel Ice Packs

    ERIC Educational Resources Information Center

    Kamata, Masahiro; Kubota, Miki

    2012-01-01

    Although cloud chambers are highly regarded as teaching aids for radiation education, school teachers have difficulty in using cloud chambers because they have to prepare dry ice or liquid nitrogen before the experiment. We developed a very simple and inexpensive cloud chamber that uses the contents of gel ice packs which can substitute for dry…

  11. Sol-Gel Derived Hafnia Coatings

    NASA Technical Reports Server (NTRS)

    Feldman, Jay D.; Stackpoole, Mairead; Blum, Yigal; Sacks, Michael; Ellerby, Don; Johnson, Sylvia M.; Venkatapathy, Ethiras (Technical Monitor)

    2002-01-01

    Sol-gel derived hafnia coatings are being developed to provide an oxidation protection layer on ultra-high temperature ceramics for potential use in turbine engines (ultra-efficient engine technology being developed by NASA). Coatings using hafnia sol hafnia filler particles will be discussed along with sol synthesis and characterization.

  12. Sol-Gel Synthesis Of Aluminoborosilicate Powders

    NASA Technical Reports Server (NTRS)

    Bull, Jeffrey; Leiser, Daniel; Selvaduray, Guna

    1992-01-01

    Application of sol-gel process to synthesis of aluminoborosilicate powders shows potential for control of microstructures of materials. Development of materials having enhanced processing characteristics prove advantageous in extending high-temperature endurance of fibrous refractory composite insulation made from ceramic fibers.

  13. Xanthan gel system effective for profile modification

    SciTech Connect

    Burkholder, L.

    1985-04-15

    To cope with the problem of optimizing reservoir sweep efficiency, many companies today are utilizing a technique known as profile modification. This technique is based on the premise that a gelled polymer formulation can be injected into the reservoir some distance beyond the well bore where it creates a flow diversion. The successful application of profile modification techniques has resulted in significant increases in incremental oil recovery. The injectant is a xanthan-gum solution precross-linked with a chromium complex to form a gel. The polymer/chromium combination reduces permeability in the thief zones and diverts a higher percentage of the displacing fluids into previously unswept, oil-saturated portions of the reservoir. Although reservoir characteristics and brine composition are key considerations, xanthan/chrome gels can be tailored to meet almost any conditions. Fractures will require strong gels while tight formations, or formations with low parting pressures, will require thinner gels. Slug volume is designed to treat the ''thief'' interval and must be carefully sized to improve sweep efficiency within economical limits.

  14. Growth of hydroxyapatite nanoparticles on silica gels.

    PubMed

    Rivera-Muñoz, E M; Huirache-Acuña, R; Velázquez, R; Alonso-Núñez, G; Eguía-Eguía, S

    2011-06-01

    Synthetic, hydroxyapatite nanoparticles were grown on the surface of silica gels. The synthesis of those nanoparticles was obtained by immersing silica gels in a simulated body fluid (SBF) at 37 degrees C. The SBF was replaced every week to keep constant the Ca and P ion concentration and subsequent growth of hydroxyapatite was evaluated after 1-6 weeks of total soaking time in SBF. Hydroxyapatite nanoparticles were observed by scanning electron microscopy (SEM) on the surface of silica gel samples and confirmed by energy dispersive X-ray spectroscopy (EDS), Fourier Transform Infra Red Spectroscopy (FTIR) and powder X-ray Diffractometry (XRD) analysis. These particles show a regular shape and uniform size every week, keeping within the nanoscale always. Both the size and morphology of hydroxyapatite nanoparticles obtained are the result of the use of different chemical additives in the synthesis of silica gels, since they affect the liquid-to-solid interface, and the growth could correspond to a diffusion limited aggregation (DLA) process. A more detailed analysis, with higher magnifications, showed that hydroxyapatite nanoparticles are not solid spheres, showing a branched texture and their size depends on the scale and resolution of the measure instrument. PMID:21770224

  15. Electrophoretic Porosimetry of Sol-Gels

    NASA Technical Reports Server (NTRS)

    Snow, L. A.; Smith, D. D.; Sibille, L.; Hunt, A. J.; Ng, J.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    It has been hypothesized that gravity has an effect on the formation and resulting microstructure of sol-gels. In order to more clearly resolve the effect of gravity, pores may be non-destructively analyzed in the wet gel, circumventing the shrinkage and coarsening associated with the drying procedure. We discuss the development of an electrophoretic technique, analogous to affinity chromatography, for the determination of pore size distribution and its application to silica gels. Specifically a monodisperse charged dye is monitored by an optical densitometer as it moves through the wet gel under the influence of an electric field. The transmittance data (output) represents the convolution of the dye concentration profile at the beginning of the run (input) with the pore size distribution (transfer function), i.e. linear systems theory applies. Because of the practical difficulty in producing a delta function input dye profile we prefer instead to use a step function. Average pore size is then related to the velocity of this dye front, while the pore size distribution is related to the spreading of the front. Preliminary results of this electrophoretic porosimetry and its application to ground and space-grown samples will be discussed.

  16. Driven Polymer Translocation into a Crosslinked Gel

    NASA Astrophysics Data System (ADS)

    Sean, David; Slater, Gary

    2015-03-01

    In a typical polymer translocation setup, a thin membrane is used to separate two chambers and a polyelectrolyte is driven by an electric field to translocate from one side of the membrane to the other via a small nanopore. However, the high translocation rate that results from the forces required to drive this process makes optical and/or electrical analysis of the translocating polymer challenging. Using coarse-grained Langevin Dynamics simulations we investigate how the translocation process can be slowed down by placing a crosslinked gel on the trans-side of the membrane. Since the driving electric field is localized in the neighborhood of the nanopore, electrophoretic migration is only achieved by a ``pushing'' action from the polymer segment residing in the nanopore. For the case of a flexible polymer we find that the polymer fills the gel pores via multiple ``herniation'' processes, whereas for a semi-flexible chain in a tight gel there are no hernias and the polymer follows a smooth curvilinear path. Moreover, for the case of a semi-flexible polymer the gel makes the translocation process more uniform by reducing the acceleration at the end of the process.

  17. 3D gel printing for soft-matter systems innovation

    NASA Astrophysics Data System (ADS)

    Furukawa, Hidemitsu; Kawakami, Masaru; Gong, Jin; Makino, Masato; Kabir, M. Hasnat; Saito, Azusa

    2015-04-01

    In the past decade, several high-strength gels have been developed, especially from Japan. These gels are expected to use as a kind of new engineering materials in the fields of industry and medical as substitutes to polyester fibers, which are materials of artificial blood vessels. We consider if various gel materials including such high-strength gels are 3D-printable, many new soft and wet systems will be developed since the most intricate shape gels can be printed regardless of the quite softness and brittleness of gels. Recently we have tried to develop an optical 3D gel printer to realize the free-form formation of gel materials. We named this apparatus Easy Realizer of Soft and Wet Industrial Materials (SWIM-ER). The SWIM-ER will be applied to print bespoke artificial organs, including artificial blood vessels, which will be possibly used for both surgery trainings and actual surgery. The SWIM-ER can print one of the world strongest gels, called Double-Network (DN) gels, by using UV irradiation through an optical fiber. Now we also are developing another type of 3D gel printer for foods, named E-Chef. We believe these new 3D gel printers will broaden the applications of soft-matter gels.

  18. Disulfide-Functionalized Diblock Copolymer Worm Gels.

    PubMed

    Warren, Nicholas J; Rosselgong, Julien; Madsen, Jeppe; Armes, Steven P

    2015-08-10

    Two strategies for introducing disulfide groups at the outer surface of RAFT-synthesized poly(glycerol monomethacrylate)-poly(2-hydroxypropyl methacrylate) (PGMA-PHPMA, or Gx-Hy for brevity) diblock copolymer worms are investigated. The first approach involved statistical copolymerization of GMA with a small amount of disulfide dimethacrylate (DSDMA, or D) comonomer to afford a G54-D0.50 macromolecular chain transfer agent (macro-CTA); this synthesis was conducted in relatively dilute solution in order to ensure mainly intramolecular cyclization and hence the formation of linear chains. Alternatively, a new disulfide-based bifunctional RAFT agent (DSDB) was used to prepare a G45-S-S-G45 (or (G45-S)2) macro-CTA. A binary mixture of a non-functionalized G55 macro-CTA was utilized with each of these two disulfide-based macro-CTAs in turn for the RAFT aqueous dispersion polymerization of 2-hydroxypropyl methacrylate (HPMA). By targeting a PHPMA DP of 130 and systematically varying the molar ratio of the two macro-CTAs, a series of disulfide-functionalized diblock copolymer worm gels were obtained. For both formulations, oscillatory rheology studies confirmed that higher disulfide contents led to stronger gels, presumably as a result of inter-worm covalent bond formation via disulfide/thiol exchange. Using the DSDB-based macro-CTA led to the strongest worm gels, and this formulation also proved to be more effective in suppressing the thermosensitive behavior that is observed for the nondisulfide-functionalized control worm gel. However, macroscopic precipitation occurred when the proportion of DSDB-based macro-CTA was increased to 50 mol %, whereas the DSDMA-based macro-CTA could be utilized at up to 80 mol %. Finally, the worm gel modulus could be reduced to that of a nondisulfide-containing worm gel by reductive cleavage of the inter-worm disulfide bonds using excess tris(2-carboxyethyl)phosphine (TCEP) to yield thiol groups. These new biomimetic worm gels are

  19. (3-Mercaptopropyl)trimethoxysilane-derived Porous Gel Monolith via Thioacetal Reaction-Assisted Sol-Gel Route

    NASA Astrophysics Data System (ADS)

    Ito, S.; Nishi, M.; Kanamori, K.; Nakanishi, K.; Kurahashi, T.; Matsubara, S.; Shimotsuma, Y.; Miura, K.; Hirao, K.

    2011-10-01

    Porous gel monolith was synthesized by reacting (3-mercaptopropyl)trimethoxysilane (MPTMS) with acetone on acidic conditions. It is known that MPTMS itself is difficult to turn into gel on acidic conditions and instead oligomers are obtained owing to the large mercaptopropyl group. In our system, the gels were obtained since acetone worked as a cross-linker via thioacetal reaction. Additionally, Au ions were selectively adsorbed on the obtained gel. When an obtained white gel was soaked in a chloroauric acid solution, the gel turned brown and was getting dark depending on the soaked time; on the other hand, the color of the solution turned from yellow to colorless.

  20. Effectiveness of Gel Repellents on Feral Pigeons

    PubMed Central

    Stock, Birte; Haag-Wackernagel, Daniel

    2013-01-01

    Simple Summary Feral pigeons live in close association in urban areas. They constitute serious health risks to humans and also lead to high economic loss due to costly damage to buildings, historic monuments, statues and even vegetation. While numerous avian repellent systems are regularly introduced onto the market, scientific proof of efficacy and their use from the point of view of animal welfare is lacking. Therefore, two avian gel repellents were studied on free-living feral pigeons in this study. The focus was set on repellent efficacy and animal welfare concerns. This study’s aim is to contribute to a better understanding of feral pigeon management in our cities. Abstract Millions of feral pigeons (Columba livia) live in close association with the human population in our cities. They pose serious health risks to humans and lead to high economic loss due to damage caused to buildings. Consequently, house owners and city authorities are not willing to allow pigeons on their buildings. While various avian repellents are regularly introduced onto the market, scientific proof of efficacy is lacking. This study aimed at testing the effectiveness of two avian gel repellents and additionally examined their application from animal welfare standpoint. The gels used an alleged tactile or visual aversion of the birds, reinforced by additional sensory cues. We mounted experimental shelves with the installed repellents in a pigeon loft and observed the behavior of free-living feral pigeons towards the systems. Both gels showed a restricted, transient repellent effect, but failed to prove the claimed complete effectiveness. Additionally, the gels’ adhesive effect remains doubtful in view of animal welfare because gluing of plumage presents a risk to feral pigeons and also to other non-target birds. This study infers that both gels lack the promised complete efficacy, conflict with animal welfare concerns and are therefore not suitable for feral pigeon management in

  1. Contrasting roles of layered structures in the molecular assembly of liquid crystal matrices on the viscoelastic properties of microparticle/liquid crystal composite gels leading to rigidification and destabilization.

    PubMed

    Yamamoto, Takahiro; Kawata, Yuki; Yoshida, Masaru

    2013-05-01

    We investigated the effects of the nematic and smectic A (SmA) phase structures of liquid crystalline matrices on the viscoelastic properties of microparticle/liquid-crystal composite gels. The storage (G') and loss (G″) moduli of the gels were largely increased in gels containing SmA matrices with a layered molecular assembly. However, the critical strain at which the gel state transformed into the sol state by the application of mechanical strain showed no significant changes with variation in the liquid crystal phase of the matrix. These results indicate that the introduction of a layered molecular assembly could be effective for rigidification of composite gels, while maintaining their critical strains. However, the composite gels tended to show a metastable state when SmA matrices were used because G' and G″ of the gels were close to each other in the entire frequency region. This behavior was in contrast to the gels with nematic matrices, which showed a larger value in G' than that in G″. The metastable state of gels with SmA matrices was also reflected in the frequency dependence of G' and in the deterioration of the recovery of the gel state after mechanical breakdown. PMID:23465188

  2. Encapsulation of nanoclusters in dried gel materials via an inverse micelle/sol gel synthesis

    DOEpatents

    Martino, Anthony; Yamanaka, Stacey A.; Kawola, Jeffrey S.; Showalter, Steven K.; Loy, Douglas A.

    1998-01-01

    A dried gel material sterically entrapping nanoclusters of a catalytically active material and a process to make the material via an inverse micelle/sol-gel synthesis. A surfactant is mixed with an apolar solvent to form an inverse micelle solution. A salt of a catalytically active material, such as gold chloride, is added along with a silica gel precursor to the solution to form a mixture. To the mixture are then added a reducing agent for the purpose of reducing the gold in the gold chloride to atomic gold to form the nanoclusters and a condensing agent to form the gel which sterically entraps the nanoclusters. The nanoclusters are normally in the average size range of from 5-10 nm in diameter with a monodisperse size distribution.

  3. Encapsulation of nanoclusters in dried gel materials via an inverse micelle/sol gel synthesis

    DOEpatents

    Martino, A.; Yamanaka, S.A.; Kawola, J.S.; Showalter, S.K.; Loy, D.A.

    1998-09-29

    A dried gel material sterically entrapping nanoclusters of a catalytically active material and a process to make the material via an inverse micelle/sol-gel synthesis are disclosed. A surfactant is mixed with an apolar solvent to form an inverse micelle solution. A salt of a catalytically active material, such as gold chloride, is added along with a silica gel precursor to the solution to form a mixture. To the mixture are then added a reducing agent for the purpose of reducing the gold in the gold chloride to atomic gold to form the nanoclusters and a condensing agent to form the gel which sterically entraps the nanoclusters. The nanoclusters are normally in the average size range of from 5--10 nm in diameter with a monodisperse size distribution. 1 fig.

  4. Characterization of porous polymethylmethacrylate space maintainers for craniofacial reconstruction.

    PubMed

    Wang, Limin; Yoon, Diana M; Spicer, Patrick P; Henslee, Allan M; Scott, David W; Wong, Mark E; Kasper, F Kurtis; Mikos, Antonios G

    2013-07-01

    Porous polymethylmethacrylate (PMMA) has been used as an alloplastic bone substitute in the craniofacial complex, showing integration with the surrounding soft and hard tissue. This study investigated the physicochemical properties of curing and cured mixtures of a PMMA-based bone cement and a carboxymethylcellulose (CMC) gel porogen. Four formulations yielding porous PMMA of varied porosity were examined; specifically, two groups containing 30% (w/w) CMC gel in the mixture using a 7% (w/v) or 9% (w/v) stock CMC gel (30-7 and 30-9, respectively) and two groups containing 40% (w/w) CMC gel (40-7 and 40-9). An additional group comprising solid PMMA without CMC was investigated. The incorporation of the CMC gel into the PMMA bone cement during polymerization decreased the setting time from 608 ± 12 s for the solid PMMA to 427 ± 10 s for the 40-9 group, and decreased the maximum temperature from 81 ± 4°C for the solid PMMA to 38 ± 2°C for the 40-9 group. The porous PMMA groups exhibited reduced compressive strength and bending modulus and strength relative to the solid PMMA. All the porous PMMA formulations released more unconverted methylmethacrylate (MMA) monomer and N,N-dimethyl-p-toluidine (DMT) from cured specimens and less MMA and DMT from curing specimens than the solid PMMA. The data suggest that the physicochemical properties of the porous PMMA formulations are appropriate for their application in craniofacial space maintenance. PMID:23359449

  5. Electrophoresis for genotyping: microtiter array diagonal gel electrophoresis on horizontal polyacrylamide gels, hydrolink, or agarose.

    PubMed

    Day, I N; Humphries, S E

    1994-11-01

    Electrophoresis of DNA has been performed traditionally in either an agarose or acrylamide gel matrix. Considerable effort has been directed to improved quality agaroses capable of high resolution, but for small fragments, such as those from polymerase chain reaction (PCR) and post-PCR digests, acrylamide still offers the highest resolution. Although agarose gels can easily be prepared in an open-faced format to gain the conveniences of horizontal electrophoresis, acrylamide does not polymerize in the presence of air and the usual configurations for gel preparation lead to electrophoresis in the vertical dimension. We describe here a very simple device and method to prepare and manipulate horizontal polyacrylamide gels (H-PAGE). In addition, the open-faced horizontal arrangement enables loading of arrays of wells. Since many procedures are undertaken in standard 96-well microtiter plates, we have also designed a device which preserves the exact configuration of the 8 x 12 array and enables electrophoresis in tracks following a 71.6 degrees diagonal between wells (MADGE, microtiter array diagonal gel electrophoresis), using either acrylamide or agarose. This eliminates almost all of the staff time taken in setup, loading, and recordkeeping and offers high resolution for genotyping pattern recognition. The nature and size of the gels allow direct stacking of gels in one tank, so that a tank used typically to analyze 30-60 samples can readily be used to analyze 1000-2000 samples. The gels would also enable robotic loading. Electrophoresis allows analysis of size and charge, parameters inaccessible to liquid-phase methods: thus, genotyping size patterns, variable length repeats, and haplotypes is possible, as well as adaptability to typing of point variations using protocols which create a difference detectable by electrophoresis. PMID:7864363

  6. Transverse agarose pore gradient gel electrophoresis of DNA.

    PubMed

    Fawcett, J S; Wheeler, D; Chrambach, A

    1992-06-01

    Transverse agarose pore gradient gels were prepared on GelBond in the concentration range of nominally 0.2-1.5% SeaKem GTG agarose, using density stabilization by glycerol and incorporation of a dye to define the gel concentration at each point on the pore gradient gel. The distribution of the dye was evaluated by photography, video-acquisition and digitization of the gradient mixture and by densitometry of the gel. The gel was applied to the electrophoresis of a 1-kb standard ladder of DNA fragments, using standard submarine apparatus. The method extends to agarose gel electrophoresis the benefits of semi-automated analysis of 'Ferguson curves' described in application to polyacrylamide gel by Wheeler et al. (J. Biochem. Biophys. Methods 24, 171-180). PMID:1640052

  7. Covalent Fusion of layered Incompatible Gels in Immiscible Solvents

    NASA Astrophysics Data System (ADS)

    Biswas, Santidan; Singh, Awaneesh; Matyjaszewski, Krzysztof; Balazs, Anna C.

    We carry out dissipative particle dynamics (DPD) simulations to model a two layered stackable gel where the gels are incompatible and are present in immiscible solvent. The bottom layer of the gel is created first and then a solution of new initiators, monomers and cross-linkers is introduced on top of it. These components then undergo polymerization and form the second gel layer. We study all possible combinations of free radical polymerization (FRP) and atom transfer radical polymerization (ATRP) mechanisms with the two layers of the gel. For example, the bottom layer gel is created via ATRP, whereas the top layer gel follows FRP. Our focus is to do a systematic study of all these combinations and find out the factors responsible for combining two incompatible gels in immiscible solvents.

  8. 48 CFR 1406.202 - Establishing or maintaining alternative sources.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... OF THE INTERIOR COMPETITION AND ACQUISITION PLANNING COMPETITION REQUIREMENTS Full and Open... authorized to approve the determinations and findings (D&Fs) to establish or maintain an alternative...

  9. 48 CFR 1406.202 - Establishing or maintaining alternative sources.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... OF THE INTERIOR COMPETITION AND ACQUISITION PLANNING COMPETITION REQUIREMENTS Full and Open... authorized to approve the determinations and findings (D&Fs) to establish or maintain an alternative...

  10. 48 CFR 1406.202 - Establishing or maintaining alternative sources.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... OF THE INTERIOR COMPETITION AND ACQUISITION PLANNING COMPETITION REQUIREMENTS Full and Open... authorized to approve the determinations and findings (D&Fs) to establish or maintain an alternative...

  11. 48 CFR 1406.202 - Establishing or maintaining alternative sources.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... OF THE INTERIOR COMPETITION AND ACQUISITION PLANNING COMPETITION REQUIREMENTS Full and Open... authorized to approve the determinations and findings (D&Fs) to establish or maintain an alternative...

  12. 48 CFR 1406.202 - Establishing or maintaining alternative sources.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... OF THE INTERIOR COMPETITION AND ACQUISITION PLANNING COMPETITION REQUIREMENTS Full and Open... authorized to approve the determinations and findings (D&Fs) to establish or maintain an alternative...

  13. 15 CFR 286.9 - Maintaining recognized status.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... INSTITUTE OF STANDARDS AND TECHNOLOGY, DEPARTMENT OF COMMERCE ACCREDITATION AND ASSESSMENT PROGRAMS NATIONAL VOLUNTARY CONFORMITY ASSESSMENT SYSTEM EVALUATION (NVCASE) PROGRAM § 286.9 Maintaining recognized...

  14. 15 CFR 286.9 - Maintaining recognized status.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... INSTITUTE OF STANDARDS AND TECHNOLOGY, DEPARTMENT OF COMMERCE ACCREDITATION AND ASSESSMENT PROGRAMS NATIONAL VOLUNTARY CONFORMITY ASSESSMENT SYSTEM EVALUATION (NVCASE) PROGRAM § 286.9 Maintaining recognized...

  15. 15 CFR 286.9 - Maintaining recognized status.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... INSTITUTE OF STANDARDS AND TECHNOLOGY, DEPARTMENT OF COMMERCE ACCREDITATION AND ASSESSMENT PROGRAMS NATIONAL VOLUNTARY CONFORMITY ASSESSMENT SYSTEM EVALUATION (NVCASE) PROGRAM § 286.9 Maintaining recognized...

  16. 15 CFR 286.9 - Maintaining recognized status.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... INSTITUTE OF STANDARDS AND TECHNOLOGY, DEPARTMENT OF COMMERCE ACCREDITATION AND ASSESSMENT PROGRAMS NATIONAL VOLUNTARY CONFORMITY ASSESSMENT SYSTEM EVALUATION (NVCASE) PROGRAM § 286.9 Maintaining recognized...

  17. 15 CFR 286.9 - Maintaining recognized status.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... INSTITUTE OF STANDARDS AND TECHNOLOGY, DEPARTMENT OF COMMERCE ACCREDITATION AND ASSESSMENT PROGRAMS NATIONAL VOLUNTARY CONFORMITY ASSESSMENT SYSTEM EVALUATION (NVCASE) PROGRAM § 286.9 Maintaining recognized...

  18. Sorption Behavior of Eu(III) into CSH Gel in Imitated Saline Groundwater - 12145

    SciTech Connect

    Funabashi, Taihei; Niibori, Yuichi; Mimura, Hitoshi

    2012-07-01

    of solid phase (in Ca/Si<0.8) in the co-presence of Na ions. On the other hand, the concentrations of Na, Ca and Si after 60 days in the solution filtrated through 0.2 μm membrane filter showed the ion exchange of Ca and Eu apparently in the samples of low Ca/Si ratio. Besides, in the samples with high Ca/Si ratio, Ca and Si concentrations in the solution were raised with increment of initial Na concentration. While Na ions may slightly increase the solubility of CSH gel, the CSH samples were stable, mostly maintaining the initial Ca/Si ratio synthesized. Moreover, the Raman spectra showed that the degree of polymerization of silicate chain in CSH samples increased with increasing Na concentration. Such an immobilized Na into the structure of CSH gel did not obstruct the incorporation of Eu{sup 3+} into CSH gel. The results mentioned above suggested that CSH gel (formed as a secondary mineral around the repository) also can retard the migration of radionuclides even if the repository and its surrounding are saturated by saline groundwater. (authors)

  19. Monolithic diphasic gels of mullite by sol-gel process under ultrasound stimulation.

    PubMed

    Vollet, D R; Donatti, D A; Domingos, R N; de Oliveira, I

    1998-06-01

    Diphasic gel in the mullite composition was prepared from a colloidal sol of boehmite mixed with a hydrolyzed tetraethoxisilane (TEOS) solution. The boehmite sol was obtained by peptization of a poorly crystallized or very small mean crystallite size (approximately 34 A) precipitate, resulting from the reaction between solutions of aluminum sulfate and sodium hydroxide. Ultrasound was utilized in the processes of the TEOS hydrolysis and the boehmite peptization, and also for complete homogenization of the mixture to gel. The wet gel is almost clear and monolithic. The gel transparency is lost on drying, when syneresis has ended, so that the interlinked pore structure starts to empty and is recovered upon water re-absorption. Cracking closely accompanies this critical drying process. Differential thermal analysis (DTA) and X-ray diffraction (XRD) show that the solid structure of the gel is composed of an amorphous silica phase, as a matrix, and a colloidal sized crystalline phase of boehmite. Upon heat treatment, the boehmite phase within the gel closely follows the same transition sequence as in pure alumina shifted towards higher temperatures. Orthorhombic mullite formation was detected at 1300 degrees C. PMID:11270341

  20. Metal-doped organic gels and method thereof

    DOEpatents

    Satcher, Jr., Joe H.; Baumann, Theodore F.

    2007-10-23

    Disclosed herein is a sol-gel polymerization process for synthesizing metal-doped organic gels. The process polymerizes metal salts of hydroxylated benzenes or hydroxylated benzene derivatives with alkyl or aryl aldehydes to form metal-doped, wet, organic gels. The gels can then be dried by supercritical solvent extraction to form metal-doped aerogels or by evaporation to form metal-doped xerogels. The aerogels and xerogels can then be pyrolyzed.

  1. Metal-doped organic gels and method thereof

    DOEpatents

    Satcher, Jr., Joe H.; Baumann, Theodore F.

    2003-09-02

    Disclosed herein is a sol-gel polymerization process for synthesizing metal-doped organic gels. The process polymerizes metal salts of hydroxylated benzenes or hydroxylated benzene derivatives with alkyl or aryl aldehydes to form metal-doped, wet, organic gels. The gels can then be dried by supercritical solvent extraction to form metal-doped aerogels or by evaporation to form metal-doped xerogels. The aerogels and xerogels can then be pyrolyzed.

  2. Electric field-induced deformation of polyelectrolyte gels

    SciTech Connect

    Adolf, D.; Hance, B.G.

    1995-08-01

    Water-swollen polyelectrolyte gels deform in an electric field. We observed that the sign and magnitude of the deformation is dependent on the nature of the salt bath in which the gel is immersed and electrocuted. These results are compatible with a deformation mechanism based upon creation of ion density gradients by the field which, in turn, creates osmotic pressure gradients within the gel. A consistent interpretation results only if gel mobility is allowed as well as free ion diffusion and migration.

  3. Methods of Manufacturing Bioactive Gels from Extracellular Matrix Material

    NASA Technical Reports Server (NTRS)

    Kentner, Kimberly A. (Inventor); Stuart, Katherine A. (Inventor); Janis, Abram D. (Inventor)

    2014-01-01

    The present invention is directed to methods of manufacturing bioactive gels from ECM material, i.e., gels which retain bioactivity, and can serve as scaffolds for preclinical and clinical tissue engineering and regenerative medicine approaches to tissue reconstruction. The manufacturing methods take advantage of a new recognition that bioactive gels from ECM material can be created by digesting particularized ECM material in an alkaline environment and neutralizing to provide bioactive gels.

  4. Methods of Manufacturing Bioactive Gels from Extracellular Matrix Material

    NASA Technical Reports Server (NTRS)

    Kentner, Kimberly A. (Inventor); Stuart, Katherine A. (Inventor); Janis, Abram D. (Inventor)

    2015-01-01

    The present invention is directed to methods of manufacturing bioactive gels from ECM material, i.e., gels which retain bioactivity, and can serve as scaffolds for preclinical and clinical tissue engineering and regenerative medicine approaches to tissue reconstruction. The manufacturing methods take advantage of a new recognition that bioactive gels from ECM material can be created by digesting particularized ECM material in an alkaline environment and neutralizing to provide bioactive gels.

  5. Methods of Manufacturing Bioactive Gels from Extracellular Matrix Material

    NASA Technical Reports Server (NTRS)

    Kentner, Kimberly A. (Inventor); Stuart, Katherine A. (Inventor); Janis, Abram D. (Inventor)

    2016-01-01

    The present invention is directed to methods of manufacturing bioactive gels from ECM material, i.e., gels which retain bioactivity, and can serve as scaffolds for preclinical and clinical tissue engineering and regenerative medicine approaches to tissue reconstruction. The manufacturing methods take advantage of a new recognition that bioactive gels from ECM material can be created by digesting particularized ECM material in an alkaline environment and neutralizing to provide bioactive gels.

  6. Superparamagnetic gel as a novel material for electromagnetically induced hyperthermia

    NASA Astrophysics Data System (ADS)

    Babincová, Melánia; Leszczynska, Danuta; Sourivong, Paul; Čičmanec, Pavol; Babinec, Peter

    2001-01-01

    Heating properties of a magnetically responsive gel in an alternating magnetic field at 217 kHz were evaluated. Superparamagnetic ferrite nanocrystals of approximately 10 nm were formed within the gel network by bridging anionic bis(ethylhexyl) sodium sulfosuccinate reverse micelles. Specific absorption rates up to 150 W/g for ferrite concentrations up to 50 mg/ml were observed. Temperature measurements of the gel without ferrite particles showed no heating effect. Magnetic gels therefore represent a novel promising hyperthermic material.

  7. Gel-forming reagents and uses thereof for preparing microarrays

    DOEpatents

    Golova, Julia; Chernov, Boris; Perov, Alexander

    2010-11-09

    New gel-forming reagents including monomers and cross-linkers, which can be applied to gel-drop microarray manufacturing by using co-polymerization approaches are disclosed. Compositions for the preparation of co-polymerization mixtures with new gel-forming monomers and cross-linker reagents are described herein. New co-polymerization compositions and cross-linkers with variable length linker groups between unsaturated C.dbd.C bonds that participate in the formation of gel networks are disclosed.

  8. Physicochemical properties of magnesium aluminum silicate (smectone) gels prepared using electrolytic-reduction ion water (2): Effects of various salts on the phase diagram.

    PubMed

    Okajima, Masahiro; Shimokawa, Ken-ichi; Ishii, Fumiyoshi

    2009-09-01

    We produced gels using electrolytic-reduction ion water and magnesium aluminum silicates (smectone), and evaluated in detail gel properties in the presence of various types of salt (NaCl, KCl, CaCl(2), MgCl(2), and AlCl(3)). Each salt was added to deionized-distilled water or electrolytic-reduction ion water, and phase diagrams for the smectone concentration (2.0-4.0%) were produced. The areas of the three phases of smectone (gel, sol, and separation) at each salt concentration were expressed as percentages of the total area. As a result, uni- and polyvalent cations (excluding Ca(2+) ions) affected the stability of gels produced using electrolytic-reduction ion water, and, particularly, univalent cations (Na(+), K(+)) markedly improved gel stability. Using electrolytic-reduction ion water as a dispersal medium, drug delivery systems (DDS) that can maintain the gelling state can be prepared. Thus, gel preparations with maintained functions or controlled-release transdermal drugs can be obtained. PMID:19477104

  9. Anaerobic ammonium oxidation in polyvinyl alcohol and sodium alginate immobilized biomass system: a potential tool to maintain anammox biomass in application.

    PubMed

    Zhu, Gang-Li; Yan, Jia; Hu, Yong-You

    2014-01-01

    Anaerobic ammonium oxidation (anammox) has been proved to be a promising nitrogen removal method for treating ammonium-rich wastewater. However, because of the low-growth rate of anammox bacteria, maintenance of a sufficient amount of anammox biomass in reactor became a key factor in application. Gel immobilization is an efficient method to prevent biomass from being washed out and to promote hyper-concentrated cultures. This study focused on a nitrogen removal process by anammox enrichment culture immobilized in polyvinyl alcohol and sodium alginate (PVA-SA) gel beads. The rapid startup of reactor demonstrated that gel entrapment was supposed to be a highly effective technique for immobilizing anammox bacteria. The anammox bacteria present in the enrichment were identified to be Jettenia-like species (>98%). Moreover, the effect of hydraulic retention time (HRT), pH, and temperature on immobilized anammox processes were investigated. The effect of pH and temperature on the anammox process was evidently weakened in PVA-SA immobilized gel beads, however, the effect of HRT on the anammox reaction was enhanced. Therefore, a stable operated reactor could be obtained in an anaerobic sequencing batch reactor, which proved gel immobilization was an excellent method to maintain the biomass in anammox reactor for application. PMID:24569269

  10. Differential Proteomic Analysis of Anthers between Cytoplasmic Male Sterile and Maintainer Lines in Capsicum annuum L

    PubMed Central

    Wu, Zhiming; Cheng, Jiaowen; Qin, Cheng; Hu, Zhiqun; Yin, Caixia; Hu, Kailin

    2013-01-01

    Cytoplasmic male sterility (CMS), widely used in the production of hybrid seeds, is a maternally inherited trait resulting in a failure to produce functional pollen. In order to identify some specific proteins associated with CMS in pepper, two-dimensional gel electrophoresis (2-DE) was applied to proteomic analysis of anthers/buds between a CMS line (designated NA3) and its maintainer (designated NB3) in Capsicum annuum L. Thirty-three spots showed more than 1.5-fold in either CMS or its maintainer. Based on mass spectrometry, 27 spots representing 23 distinct proteins in these 33 spots were identified. Proteins down-regulated in CMS anthers/buds includes ATP synthase D chain, formate dehydrogenase, alpha-mannosidas, RuBisCO large subunit-binding protein subunit beta, chloroplast manganese stabilizing protein-II, glutathione S-transferase, adenosine kinase isoform 1T-like protein, putative DNA repair protein RAD23-4, putative caffeoyl-CoA 3-O-methyltransferase, glutamine synthetase (GS), annexin Cap32, glutelin, allene oxide cyclase, etc. In CMS anthers/buds, polyphenol oxidase, ATP synthase subunit beta, and actin are up-regulated. It was predicted that male sterility in NA3 might be related to energy metabolism turbulence, excessive ethylene synthesis, and suffocation of starch synthesis. The present study lays a foundation for future investigations of gene functions associated with pollen development and cytoplasmic male sterility, and explores the molecular mechanism of CMS in pepper. PMID:24264042

  11. Manganese superoxide dismutase is required to maintain osteoclast differentiation and function under static force

    PubMed Central

    Guo, Tao; Zhang, Liqiang; Konermann, Anna; Zhou, Hong; Jin, Fang; Liu, Wenjia

    2015-01-01

    Bone homeostasis is maintained by the balance of osteoblasts (OBs) and osteoclasts (OCs). Increased activity of OCs not only contributes to pathological bone resorption, such as osteoporosis and periodontitis, but also is responsible for physiological conditions like orthodontic tooth movement (OTM). However, the detailed mechanism by which orthodontic force promotes the formation of OCs is still poorly understood. In this study, we confirmed that static force promoted the differentiation of human cord monocytes (HMNCs) into OCs depending on loading time and magnitude. Protein expression profiles among HMNCs, HMNCs subjected to static force and mature OCs were established via 2-DE and MALDI-TOF-MS analyses. Total respective protein spot numbers of 549 ± 13, 612 ± 19 and 634 ± 16 were detected in each of the gels by image analysis. The five proteins identified were plasminogen activator inhibitor 2 (PAI-2, Spot 1), peroxiredoxin-6 (PRD-6, Spot 3), manganese superoxide dismutase (SOD2, Spot 6), Rho GDP-dissociation inhibitor 2 (Rho-GDI2, Spot 11) and L-lactate dehydrogenase B chain (L-LDH, Spot 15). More importantly, we revealed that SOD2 was required to maintain monocyte differentiation into functional OCs and may become a potential target for regulating the efficiency of OTM in the future. PMID:25619900

  12. 21 CFR 872.1730 - Electrode gel for pulp testers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Diagnostic Devices § 872.1730 Electrode gel for pulp testers. (a) Identification. An electrode gel for pulp testers is a device intended to be applied to the surface of a tooth... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Electrode gel for pulp testers. 872.1730...

  13. 21 CFR 872.1730 - Electrode gel for pulp testers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Diagnostic Devices § 872.1730 Electrode gel for pulp testers. (a) Identification. An electrode gel for pulp testers is a device intended to be applied to the surface of a tooth... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Electrode gel for pulp testers. 872.1730...

  14. Electrochemical stimulation and control of electroactive polymer gels

    NASA Astrophysics Data System (ADS)

    Guelch, Rainer W.; Holdenried, Jens; Weible, Andrea; Wallmersperger, Thomas; Kroeplin, Bernd

    2001-07-01

    Direct effects of electrical currents on polyelectrolyte gels are always associated with changes in their Donnan potential. Thus electrical stimulation of gels can be only completely understood if the direct effect of electric fields on the potential profile within the gels are known. The purpose of this study is to present recordings of Donnan potentials in electroactive gels of various compositions, especially under the influence of electric fields. An important finding is that opposite alterations in the Donnan potential simultaneously occur at the current inflow and outflow region of the gel. In anionic gels hyperpolarization, i.e. higher negativity, is induced on the anode-side of the gel, whereas depolarization is found on the cathode-side. As these shifts in the potential are supposed to affect swelling or deswelling of polyelectrolyte gels, they will primarily promote bending motions of the gel. To demonstrate the opposite bending behavior of anionic and cationic polymer gels under the influence of an electric field a short video sequence of an EAP gripper in action is presented. It is made exclusively of polyelectrolyte gel strips taking advantage of the fact that anionic and cationic polyacrylamide gels can be attached firmly to each other without any adhesive.

  15. Retention and release behavior of insulin in chitosan gel beads.

    PubMed

    Kofuji, Kyoko; Akamine, Hiroyuki; Oshirabe, Hitomi; Maeda, Yasuyo; Murata, Yoshifumi; Kawashima, Susumu

    2003-01-01

    Chitosan (CS) gel beads were prepared in a 10% (w/v) aqueous amino acid solution (pH 9.0) as a vehicle for delivering peptide and protein drugs. CS gel beads with a weight-average molecular weight of (16-280) x 10(4) were employed in this study. Preparation of the CS gel beads was affected by properties such as molecular weight and degree of deacetylation. Insulin, which is commonly used to assess protein drug delivery, was retained in the CS gel beads. Drug release from the CS gel beads was governed by diffusion of drug from the gel matrix. Sustained release of insulin from the CS gel beads was observed, despite the fact that insulin is a comparatively water-soluble drug. because insulin formed a complex with CS. Modification of the CS gel matrix by chondroitin sulfate inhibited release of insulin from the gel beads. CS gel beads were implanted into air pouches prepared subcutaneously on the dorsal surface of diabetic mice in order to investigate the efficacy of insulin retained in the CS beads. Blood glucose levels were found to be reduced after implantation of CS gel beads retaining insulin. CS gel beads may possibly improve the stability and control of insulin release. These observations indicate that CS beads are a promising biocompatible and biodegradable vehicle for peptide and protein delivery. PMID:14768911

  16. Formulation and method for preparing gels comprising hydrous aluminum oxide

    SciTech Connect

    Collins, Jack L.

    2014-06-17

    Formulations useful for preparing hydrous aluminum oxide gels contain a metal salt including aluminum, an organic base, and a complexing agent. Methods for preparing gels containing hydrous aluminum oxide include heating a formulation to a temperature sufficient to induce gel formation, where the formulation contains a metal salt including aluminum, an organic base, and a complexing agent.

  17. Formulation and method for preparing gels comprising hydrous cerium oxide

    DOEpatents

    Collins, Jack L; Chi, Anthony

    2013-05-07

    Formulations useful for preparing hydrous cerium oxide gels contain a metal salt including cerium, an organic base, and a complexing agent. Methods for preparing gels containing hydrous cerium oxide include heating a formulation to a temperature sufficient to induce gel formation, where the formulation contains a metal salt including cerium, an organic base, and a complexing agent.

  18. Formulation and method for preparing gels comprising hydrous hafnium oxide

    DOEpatents

    Collins, Jack L; Hunt, Rodney D; Montgomery, Frederick C

    2013-08-06

    Formulations useful for preparing hydrous hafnium oxide gels contain a metal salt including hafnium, an acid, an organic base, and a complexing agent. Methods for preparing gels containing hydrous hafnium oxide include heating a formulation to a temperature sufficient to induce gel formation, where the formulation contains a metal salt including hafnium, an acid, an organic base, and a complexing agent.

  19. Laser based on dye-activated silica gel

    SciTech Connect

    Altshuler, G.B.; Bakhanov, V.A.; Dulneva, E.G.; Erofeev, A.V.; Mazurin, O.V.; Roskova, G.P.; Tsekhomskaya, T.S.

    1987-06-01

    Silica gel activated by a dye is used as a new laser medium. The lasin characteristics of rhodamine 6G in silica gel are reported. An important characteristic of the dye laser is its long service life, which is determined by the photostability of the dye in silic gel.(AIP)

  20. 21 CFR 520.1453 - Moxidectin and praziquantel gel.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Moxidectin and praziquantel gel. 520.1453 Section 520.1453 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... and praziquantel gel. (a) Specifications. Each milliliter of gel contains 20 milligrams (mg)...

  1. Evaluation of a Thermoprotective Gel for Hydrodissection During Percutaneous Microwave Ablation: In Vivo Results

    SciTech Connect

    Moreland, Anna J. Lubner, Meghan G. Ziemlewicz, Timothy J. Kitchin, Douglas R. Hinshaw, J. Louis Johnson, Alexander D. Lee, Fred T. Brace, Christopher L.

    2015-06-15

    PurposeTo evaluate whether thermoreversible poloxamer 407 15.4 % in water (P407) can protect non-target tissues adjacent to microwave (MW) ablation zones in a porcine model.Materials and MethodsMW ablation antennas were placed percutaneously into peripheral liver, spleen, or kidney (target tissues) under US and CT guidance in five swine such that the expected ablation zones would extend into adjacent diaphragm, body wall, or bowel (non-target tissues). For experimental ablations, P407 (a hydrogel that transitions from liquid at room temperature to semi-solid at body temperature) was injected into the potential space between target and non-target tissues, and the presence of a gel barrier was verified on CT. No barrier was used for controls. MW ablation was performed at 65 W for 5 min. Thermal damage to target and non-target tissues was evaluated at dissection.ResultsAntennas were placed 7 ± 3 mm from the organ surface for both control and gel-protected ablations (p = 0.95). The volume of gel deployed was 49 ± 27 mL, resulting in a barrier thickness of 0.8 ± 0.5 cm. Ablations extended into non-target tissues in 12/14 control ablations (mean surface area = 3.8 cm{sup 2}) but only 4/14 gel-protected ablations (mean surface area = 0.2 cm{sup 2}; p = 0.0005). The gel barrier remained stable at the injection site throughout power delivery.ConclusionWhen used as a hydrodissection material, P407 protected non-targeted tissues and was successfully maintained at the injection site for the duration of power application. Continued investigations to aid clinical translation appear warranted.

  2. Study of a non-diffusing radiochromic gel dosimeter for 3D radiation dose imaging

    NASA Astrophysics Data System (ADS)

    Marsden, Craig Michael

    2000-12-01

    This thesis investigates the potential of a new radiation gel dosimeter, based on nitro-blue tetrazolium (NBTZ) suspended in a gelatin mold. Unlike all Fricke based gel dosimeters this dosimeter does not suffer from diffusive loss of image stability. Images are obtained by an optical tomography method. Nitro blue tetrazolium is a common biological indicator that when irradiated in an aqueous medium undergoes reduction to a highly colored formazan, which has an absorbance maximum at 525nm. Tetrazolium is water soluble while the formazan product is insoluble. The formazan product sticks to the gelatin matrix and the dose image is maintained for three months. Methods to maximize the sensitivity of the system were evaluated. It was found that a chemical detergent, Triton X-100, in combination with sodium formate, increased the dosimeter sensitivity significantly. An initial G-value of formazan production for a dosimeter composed of 1mM NBTZ, gelatin, and water was on the order of 0.2. The addition of Triton and formate produced a G-value in excess of 5.0. The effects of NBTZ, triton, formate, and gel concentration were all investigated. All the gels provided linear dose vs. absorbance plots for doses from 0 to >100 Gy. It was determined that gel concentration had minimal if any effect on sensitivity. Sensitivity increased slightly with increasing NBTZ concentration. Triton and formate individually and together provided moderate to large increases in dosimeter sensitivity. The dosimeter described in this work can provide stable 3D radiation dose images for all modalities of radiation therapy equipment. Methods to increase sensitivity are developed and discussed.

  3. Maintaining News Files. Student's Manual and Instructor's Manual.

    ERIC Educational Resources Information Center

    McLeod, Sadie

    Supporting performance objective 19 of the V-TECS (Vocational-Technical Education Consortium of States) Secretarial Catalog, both a set of student materials and an instructor's manual on maintaining news files are included in this packet. (The packet is the ninth in a set of nine on maintaining files and a library--CE 016 939 947.) the student…

  4. 49 CFR 1310.2 - Requirement to maintain tariffs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 9 2010-10-01 2010-10-01 false Requirement to maintain tariffs. 1310.2 Section... HOUSEHOLD GOODS CARRIERS § 1310.2 Requirement to maintain tariffs. (a) Except when providing transportation... of a facility that affects the value of that transportation or service, or through another...

  5. 48 CFR 6.202 - Establishing or maintaining alternative sources.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... particular source from a contract action in order to establish or maintain an alternative source or sources...) Increase or maintain competition and likely result in reduced overall costs for the acquisition, or for any anticipated acquisition; (2) Be in the interest of national defense in having a facility (or a...

  6. 7 CFR 3560.103 - Maintaining housing projects.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 15 2011-01-01 2011-01-01 false Maintaining housing projects. 3560.103 Section 3560.103 Agriculture Regulations of the Department of Agriculture (Continued) RURAL HOUSING SERVICE, DEPARTMENT OF AGRICULTURE DIRECT MULTI-FAMILY HOUSING LOANS AND GRANTS Borrower Management and Operations Responsibilities § 3560.103 Maintaining...

  7. 7 CFR 3560.103 - Maintaining housing projects.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 15 2012-01-01 2012-01-01 false Maintaining housing projects. 3560.103 Section 3560.103 Agriculture Regulations of the Department of Agriculture (Continued) RURAL HOUSING SERVICE, DEPARTMENT OF AGRICULTURE DIRECT MULTI-FAMILY HOUSING LOANS AND GRANTS Borrower Management and Operations Responsibilities § 3560.103 Maintaining...

  8. 19 CFR 143.6 - Failure to maintain performance standards.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 19 Customs Duties 2 2011-04-01 2011-04-01 false Failure to maintain performance standards. 143.6 Section 143.6 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY (CONTINUED) SPECIAL ENTRY PROCEDURES Automated Broker Interface § 143.6 Failure to maintain performance standards....

  9. 48 CFR 906.202 - Establishing or maintaining alternative sources.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... maintaining alternative sources. 906.202 Section 906.202 Federal Acquisition Regulations System DEPARTMENT OF ENERGY COMPETITION ACQUISITION PLANNING COMPETITION REQUIREMENTS Full and Open Competition After Exclusion of Sources 906.202 Establishing or maintaining alternative sources. (b)(1) Every proposed...

  10. Cantilever springs maintain tension in thermally expanded wires

    NASA Technical Reports Server (NTRS)

    Terselic, R. A.

    1965-01-01

    Two deflected cantilever springs strung with wire provide force displacement compensation to maintain tension in the wires as they undergo thermal expansion. This method of maintaining tension in thermally expanded wires is used in electric space heaters and residential heat exchangers.

  11. Species interaction mechanisms maintain grassland plant species diversity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Theory has outpaced empirical research in pursuit of identifying mechanisms maintaining species diversity. Here we demonstrate how data from diversity-ecosystem functioning experiments can be used to test maintenance of diversity theory. We predict that grassland plant diversity can be maintained by...

  12. Continuous microbial cultures maintained by electronically-controlled device

    NASA Technical Reports Server (NTRS)

    Eisler, W. J., Jr.; Webb, R. B.

    1967-01-01

    Photocell-controlled instrument maintains microbial culture. It uses commercially available chemostat glassware, provides adequate aeration through bubbling of the culture, maintains the population size and density, continuously records growth rates over small increments of time, and contains a simple, sterilizable nutrient control mechanism.

  13. Object Representations Maintain Attentional Control Settings across Space and Time

    ERIC Educational Resources Information Center

    Schreij, Daniel; Olivers, Christian N. L.

    2009-01-01

    Previous research has revealed that we create and maintain mental representations for perceived objects on the basis of their spatiotemporal continuity. An important question is what type of information can be maintained within these so-called object files. We provide evidence that object files retain specific attentional control settings for…

  14. 49 CFR 1104.14 - Protective orders to maintain confidentiality.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...-SERVICE-PLEADINGS, GENERALLY § 1104.14 Protective orders to maintain confidentiality. (a) Segregation of... 49 Transportation 8 2010-10-01 2010-10-01 false Protective orders to maintain confidentiality... on the outside “Confidential materials subject to a request for a protective order.” (b) Requests...

  15. 49 CFR 1104.14 - Protective orders to maintain confidentiality.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...-SERVICE-PLEADINGS, GENERALLY § 1104.14 Protective orders to maintain confidentiality. (a) Segregation of... 49 Transportation 8 2011-10-01 2011-10-01 false Protective orders to maintain confidentiality... on the outside “Confidential materials subject to a request for a protective order.” (b) Requests...

  16. 22 CFR 171.2 - Types of records maintained.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 22 Foreign Relations 1 2013-04-01 2013-04-01 false Types of records maintained. 171.2 Section 171.2 Foreign Relations DEPARTMENT OF STATE ACCESS TO INFORMATION AVAILABILITY OF INFORMATION AND RECORDS TO THE PUBLIC General Policy and Procedures § 171.2 Types of records maintained. Most of...

  17. 31 CFR 205.24 - How are accurate estimates maintained?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false How are accurate estimates maintained... Treasury-State Agreement § 205.24 How are accurate estimates maintained? (a) If a State has knowledge that an estimate does not reasonably correspond to the State's cash needs for a Federal assistance...

  18. 30 CFR 870.22 - Maintaining required production records.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Maintaining required production records. 870.22... INTERIOR ABANDONED MINE LAND RECLAMATION ABANDONED MINE RECLAMATION FUND-FEE COLLECTION AND COAL PRODUCTION REPORTING § 870.22 Maintaining required production records. (a) If you engage in or conduct a surface...

  19. 33 CFR 150.555 - How must cranes be maintained?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Operations § 150.555 How must cranes be maintained? Cranes must be operated, maintained, and tested in accordance with 46 CFR part 109, subpart F. ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false How must cranes be...

  20. 33 CFR 150.555 - How must cranes be maintained?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Operations § 150.555 How must cranes be maintained? Cranes must be operated, maintained, and tested in accordance with 46 CFR part 109, subpart F. ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false How must cranes be...

  1. 33 CFR 150.555 - How must cranes be maintained?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Operations § 150.555 How must cranes be maintained? Cranes must be operated, maintained, and tested in accordance with 46 CFR part 109, subpart F. ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false How must cranes be...

  2. 33 CFR 150.555 - How must cranes be maintained?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Operations § 150.555 How must cranes be maintained? Cranes must be operated, maintained, and tested in accordance with 46 CFR part 109, subpart F. ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false How must cranes be...

  3. 33 CFR 150.555 - How must cranes be maintained?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Operations § 150.555 How must cranes be maintained? Cranes must be operated, maintained, and tested in accordance with 46 CFR part 109, subpart F. ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false How must cranes be...

  4. 19 CFR 163.2 - Persons required to maintain records.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 19 Customs Duties 2 2011-04-01 2011-04-01 false Persons required to maintain records. 163.2 Section 163.2 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY (CONTINUED) RECORDKEEPING § 163.2 Persons required to maintain records....

  5. 27 CFR 555.123 - Records maintained by licensed manufacturers.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 3 2014-04-01 2014-04-01 false Records maintained by licensed manufacturers. 555.123 Section 555.123 Alcohol, Tobacco Products, and Firearms BUREAU OF ALCOHOL... Reports § 555.123 Records maintained by licensed manufacturers. (a) Each licensed manufacturer shall...

  6. 27 CFR 478.123 - Records maintained by manufacturers.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 3 2014-04-01 2014-04-01 false Records maintained by manufacturers. 478.123 Section 478.123 Alcohol, Tobacco Products, and Firearms BUREAU OF ALCOHOL, TOBACCO... Records § 478.123 Records maintained by manufacturers. (a) Each licensed manufacturer shall record...

  7. 27 CFR 555.123 - Records maintained by licensed manufacturers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 3 2012-04-01 2010-04-01 true Records maintained by licensed manufacturers. 555.123 Section 555.123 Alcohol, Tobacco Products, and Firearms BUREAU OF ALCOHOL... Reports § 555.123 Records maintained by licensed manufacturers. (a) Each licensed manufacturer shall...

  8. 27 CFR 478.123 - Records maintained by manufacturers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 3 2012-04-01 2010-04-01 true Records maintained by manufacturers. 478.123 Section 478.123 Alcohol, Tobacco Products, and Firearms BUREAU OF ALCOHOL, TOBACCO... Records § 478.123 Records maintained by manufacturers. (a) Each licensed manufacturer shall record...

  9. 41 CFR 51-4.3 - Maintaining qualification.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 41 Public Contracts and Property Management 1 2010-07-01 2010-07-01 true Maintaining qualification. 51-4.3 Section 51-4.3 Public Contracts and Property Management Other Provisions Relating to Public Contracts COMMITTEE FOR PURCHASE FROM PEOPLE WHO ARE BLIND OR SEVERELY DISABLED 4-NONPROFIT AGENCIES § 51-4.3 Maintaining qualification. (a)...

  10. 2 CFR 182.40 - How is the guidance maintained?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 2 Grants and Agreements 1 2010-01-01 2010-01-01 false How is the guidance maintained? 182.40 Section 182.40 Grants and Agreements OFFICE OF MANAGEMENT AND BUDGET GOVERNMENTWIDE GUIDANCE FOR GRANTS AND AGREEMENTS Reserved GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) § 182.40 How is the guidance maintained? The...

  11. Evolving Reliability and Maintainability Allocations for NASA Ground Systems

    NASA Technical Reports Server (NTRS)

    Munoz, Gisela; Toon, T.; Toon, J.; Conner, A.; Adams, T.; Miranda, D.

    2016-01-01

    This paper describes the methodology and value of modifying allocations to reliability and maintainability requirements for the NASA Ground Systems Development and Operations (GSDO) programs subsystems. As systems progressed through their design life cycle and hardware data became available, it became necessary to reexamine the previously derived allocations. This iterative process provided an opportunity for the reliability engineering team to reevaluate allocations as systems moved beyond their conceptual and preliminary design phases. These new allocations are based on updated designs and maintainability characteristics of the components. It was found that trade-offs in reliability and maintainability were essential to ensuring the integrity of the reliability and maintainability analysis. This paper discusses the results of reliability and maintainability reallocations made for the GSDO subsystems as the program nears the end of its design phase.

  12. Evolving Reliability and Maintainability Allocations for NASA Ground Systems

    NASA Technical Reports Server (NTRS)

    Munoz, Gisela; Toon, Troy; Toon, Jamie; Conner, Angelo C.; Adams, Timothy C.; Miranda, David J.

    2016-01-01

    This paper describes the methodology and value of modifying allocations to reliability and maintainability requirements for the NASA Ground Systems Development and Operations (GSDO) program’s subsystems. As systems progressed through their design life cycle and hardware data became available, it became necessary to reexamine the previously derived allocations. This iterative process provided an opportunity for the reliability engineering team to reevaluate allocations as systems moved beyond their conceptual and preliminary design phases. These new allocations are based on updated designs and maintainability characteristics of the components. It was found that trade-offs in reliability and maintainability were essential to ensuring the integrity of the reliability and maintainability analysis. This paper discusses the results of reliability and maintainability reallocations made for the GSDO subsystems as the program nears the end of its design phase.

  13. Evolving Reliability and Maintainability Allocations for NASA Ground Systems

    NASA Technical Reports Server (NTRS)

    Munoz, Gisela; Toon, Jamie; Toon, Troy; Adams, Timothy C.; Miranda, David J.

    2016-01-01

    This paper describes the methodology that was developed to allocate reliability and maintainability requirements for the NASA Ground Systems Development and Operations (GSDO) program's subsystems. As systems progressed through their design life cycle and hardware data became available, it became necessary to reexamine the previously derived allocations. Allocating is an iterative process; as systems moved beyond their conceptual and preliminary design phases this provided an opportunity for the reliability engineering team to reevaluate allocations based on updated designs and maintainability characteristics of the components. Trade-offs in reliability and maintainability were essential to ensuring the integrity of the reliability and maintainability analysis. This paper will discuss the value of modifying reliability and maintainability allocations made for the GSDO subsystems as the program nears the end of its design phase.

  14. Droplet Spreading with Sol-Gel Transition

    NASA Astrophysics Data System (ADS)

    Jalaal, Maziyar; Stoeber, Boris; Balmforth, Neil J.

    2014-11-01

    The impact and spreading of liquid droplets on a smooth solid substrate is a classical subject with several industrial applications such as ink-jet printing, spray cooling, coating, and many others. For many of these deposition processes, controlling the final shape of the drop is critical. In the current research, a new technique for controlling the spreading of droplets impacting a substrate is presented. This technique exploits the rheology of a thermo-responsive polymer solution that undergoes a reversible sol/gel transition above a critical temperature. Experiments are conducted using a combination of shadowgraphy and micro-PIV to observe spreading drops. It is shown that the final diameter of a droplet can be controlled through the temperature of the substrate and the tunable sol/gel transition temperature of the fluid.A mathematical model is provided to further elucidate the flow dynamics.

  15. Novel carboxy functionalized sol-gel precursors

    SciTech Connect

    Wolter, H.; Storch, W.; Gellermann, C.

    1996-12-31

    A novel family of inorganic-organic copolymers (ORMOCER`s) derived from urethane- and thioether(meth)acrylate alkoxysilanes has been successfully exploited for a variety of diverse applications. In order to widen the range of applications an additional functionality (carboxy group) has been incorporated int his silane type. Conventional sol-gel processing facilitates the formation of an inorganic Si-O-Si-network via hydrolysis and polycondensation reactions of alkoxysilyl moieties and in addition, the (meth)acrylate groups are available for radically induced polymerization to obtain a complementary organic polymer structure. The presence of a carboxy group would appear to have great potential for a range of diverse areas of application, such as an internal catalyst for the sol-gel process, complexation of elements such as Zr and Ti, increasing the adhesion to various substrates and modification of solubility. A number of novel silanes and their syntheses will be described in this paper.

  16. Carbon Redox-Polymer-Gel Hybrid Supercapacitors

    NASA Astrophysics Data System (ADS)

    Vlad, A.; Singh, N.; Melinte, S.; Gohy, J.-F.; Ajayan, P. M.

    2016-02-01

    Energy storage devices that provide high specific power without compromising on specific energy are highly desirable for many electric-powered applications. Here, we demonstrate that polymer organic radical gel materials support fast bulk-redox charge storage, commensurate to surface double layer ion exchange at carbon electrodes. When integrated with a carbon-based electrical double layer capacitor, nearly ideal electrode properties such as high electrical and ionic conductivity, fast bulk redox and surface charge storage as well as excellent cycling stability are attained. Such hybrid carbon redox-polymer-gel electrodes support unprecedented discharge rate of 1,000C with 50% of the nominal capacity delivered in less than 2 seconds. Devices made with such electrodes hold the potential for battery-scale energy storage while attaining supercapacitor-like power performances.

  17. Freezing D2O clay gels.

    PubMed

    Letellier, M

    1998-01-01

    To obtain the T1 surface value in smectites/D2O diluted suspensions or gels, as was obtained on a monolayer deuterated clay, we freeze them. The broad Pake's doublets similar to ice doublets and with the same T1 show that we can separate frozen from unfrozen D2O. The latter exhibits a narrower line and a single T1 and is attributed to the liquid surface water layer in rapid exchange with the nearby supercooled water, the quantity of which diminishes with the lowering of the temperature depending on the gel porosity. It is possible to measure the supercooled water quantity and to correct the T1 measured values to extract the T1 surface. The value extrapolated at room temperature allows the complete clay surface area measurement. The example of a montmorillonite is given and a comparison with laponite is made. PMID:9803898

  18. Carbon Redox-Polymer-Gel Hybrid Supercapacitors.

    PubMed

    Vlad, A; Singh, N; Melinte, S; Gohy, J-F; Ajayan, P M

    2016-01-01

    Energy storage devices that provide high specific power without compromising on specific energy are highly desirable for many electric-powered applications. Here, we demonstrate that polymer organic radical gel materials support fast bulk-redox charge storage, commensurate to surface double layer ion exchange at carbon electrodes. When integrated with a carbon-based electrical double layer capacitor, nearly ideal electrode properties such as high electrical and ionic conductivity, fast bulk redox and surface charge storage as well as excellent cycling stability are attained. Such hybrid carbon redox-polymer-gel electrodes support unprecedented discharge rate of 1,000C with 50% of the nominal capacity delivered in less than 2 seconds. Devices made with such electrodes hold the potential for battery-scale energy storage while attaining supercapacitor-like power performances. PMID:26917470

  19. Optical-CT scanning of polymer gels

    PubMed Central

    Oldham, M

    2006-01-01

    The application of optical-CT scanning to achieve accurate high-resolution 3D dosimetry is a subject of current interest. The purpose of this paper is to provide a brief overview of past research and achievements in optical-CT polymer gel dosimetry, and to review current issues and challenges. The origins of optical-CT imaging of light-scattering polymer gels are reviewed. Techniques to characterize and optimize optical-CT performance are presented. Particular attention is given to studies of artifacts in optical-CT imaging, an important area that has not been well studied to date. The technique of optical-CT simulation by Monte-Carlo modeling is introduced as a tool to explore such artifacts. New simulation studies are presented and compared with experimental data. PMID:17082823

  20. Molecular recognition in gels, monolayers, and solids

    NASA Astrophysics Data System (ADS)

    Prime, Kevin L.; Chu, Yen-Ho; Schmid, Walther; Seto, Christopher T.; Chen, James K.

    1991-12-01

    This paper describes work in four areas: affinity electrophoresis of carbonic anhydrase in cross-linked polyacrylamide derived gels containing immobilized derivatives of aryl sulfonamides; inhibition of the hemagglutination of erythrocytes induced by influenza virus using water-soluble polyacrylamides bearing sialic acid groups; the application of self-assembled monolayers (SAMs) of alkyl thiolates on gold to the study of protein adsorption on organic surfaces; and the use of networks of hydrogen bonds to generate new classes of non-covalently assembled organic materials, both in solution and in crystals. This paper summarizes research in two areas of molecular recognition: affinity polymers and molecular self assembly. We illustrate these areas by examples drawn from affinity gel electrophoresis, soluble synthetic macromolecular inhibitors of binding of influenza virus to erythrocytes protein adsorption on self assembled monolayers and self assembling hydrogen bonded molecular aggregates.

  1. Comparative proteomics and difference gel electrophoresis.

    PubMed

    Minden, Jonathan

    2007-12-01

    The goal of comparative proteomics is to analyze proteome changes in response to development, disease, or environment. This is a two-step process in which proteins within cellular extracts are first fractionated to reduce sample complexity, and then the proteins are identified by mass spectrometry. Two-dimensional electrophoresis (2DE) is the long-time standard for protein separation, but it has suffered from poor reproducibility and limited sensitivity. Difference gel electrophoresis (DIGE), in which two protein samples are separately labeled with different fluorescent dyes and then co-electrophoresed on the same 2DE gel, was developed to overcome the reproducibility and sensitivity limitations. In this essay, I discuss the principles of comparative proteomics and the development of DIGE. PMID:18251249

  2. Carbon Redox-Polymer-Gel Hybrid Supercapacitors

    PubMed Central

    Vlad, A.; Singh, N.; Melinte, S.; Gohy, J.-F.; Ajayan, P.M.

    2016-01-01

    Energy storage devices that provide high specific power without compromising on specific energy are highly desirable for many electric-powered applications. Here, we demonstrate that polymer organic radical gel materials support fast bulk-redox charge storage, commensurate to surface double layer ion exchange at carbon electrodes. When integrated with a carbon-based electrical double layer capacitor, nearly ideal electrode properties such as high electrical and ionic conductivity, fast bulk redox and surface charge storage as well as excellent cycling stability are attained. Such hybrid carbon redox-polymer-gel electrodes support unprecedented discharge rate of 1,000C with 50% of the nominal capacity delivered in less than 2 seconds. Devices made with such electrodes hold the potential for battery-scale energy storage while attaining supercapacitor-like power performances. PMID:26917470

  3. Innovative materials based on sol gel technology

    NASA Astrophysics Data System (ADS)

    Reisfeld, Renata; Saraidarov, Tsiala

    2006-01-01

    We review the sol-gel based new materials which were prepared in our laboratory including: tunable lasers, active waveguides, luminescent solar concentrators, electrochromic, photochromic and gasochromic plates for smart windows, chemical and biological sensors, semiconductor quantum dots and complexes of rare earth ions. In this paper we present the firstly obtained results of the Eu sulfide nanocrystalline (NCs) powder material and doped in the sol-gel based zirconia films. The powder and films were studied by high resolution transmittance electron microscopy (HRTEM), energy dispersive X-ray spectroscopy analysis (EDS) and luminescence spectroscopy. Eu sulfide nanocrystals (NCs) ranging between 8 and 10 nm were obtained as powder and 3-4 nm incorporated in zirconia film.

  4. Electrodeposited gels prepared from protein alloys

    PubMed Central

    Lin, Yinan; Wang, Siran; Chen, Ying; Wang, Qianrui; Burke, Kelly A; Spedden, Elise M; Staii, Cristian; Weiss, Anthony S; Kaplan, David L

    2015-01-01

    Aim Silk-tropoelastin alloys, composed of recombinant human tropoelastin and regenerated Bombyx mori silk fibroin, are an emerging, versatile class of biomaterials endowed with tunable combinations of physical and biological properties. Electrodeposition of these alloys provides a programmable means to assemble functional gels with both spatial and temporal controllability. Materials & methods Tropoelastin-modified silk was prepared by enzymatic coupling between tyrosine residues. Hydrogel coatings were electrodeposited using two wire electrodes. Results & discussion Mechanical characterization and in vitro cell culture revealed enhanced adhesive capability and cellular response of these alloy gels as compared with electrogelled silk alone. Conclusion These electro-depositable silk-tropoelastin alloys constitute a suitable coating material for nanoparticle-based drug carriers and offer a novel opportunity for on-demand encapsulation/release of nanomedicine. PMID:25816881

  5. Deterioration of white croaker (Pennahia argentata) meat thermally-induced gel products caused by proteolytic enzymes in the contaminated intestine and kidney.

    PubMed

    Ueki, Nobuhiko; Wan, Jianrong; Watabe, Shugo

    2016-05-15

    Thermally-induced gels were made from white croaker (Pennahia argentata) meat in the presence of its organ extracts by pre-heating at 40 and 65°C for 20 min and subsequent heating at 85°C for 20 min. The breaking strength of the gels decreased with increasing concentrations of the intestinal extracts accompanying decomposition of myosin heavy chains. However, no significant changes in the gel strength occurred when the kidney extract was added. The proteolytic activity in the intestinal extracts examined in the meat homogenate had a maximum at 60°C and pH 8.90. These results suggest that the intestinal rather than kidney proteolytic activities are responsible for gel softening known as a modori phenomenon. Thus, the removal of intestinal tracts is essential to maintain a high quality of surimi-based products. PMID:26775990

  6. Diffusion of polyelectrolytes in polyelectrolyte gels

    NASA Astrophysics Data System (ADS)

    Rahalkar, Anand; Muthukumar, Murugappan

    2015-03-01

    Using dynamic light scattering, we have investigated the diffusion coefficient of sodium poly(styrene sulfonate) in a matrix of poly(acrylamide-co-acrylate) gels. The diffusion coefficient of the probe polyelectrolyte exhibits a crossover behavior from a particle-diffusion to entropic-barrier dominated diffusion, as the molecular weight is increased. The effect of electrostatics, by varying the charge density of the matrix, on probe diffusion constant will be presented.

  7. Ring-Resonator/Sol-Gel Interferometric Immunosensor

    NASA Technical Reports Server (NTRS)

    Bearman, Gregory; Cohen, David

    2007-01-01

    A proposed biosensing system would be based on a combination of (1) a sensing volume containing antibodies immobilized in a sol-gel matrix and (2) an optical interferometer having a ring resonator configuration. The antibodies would be specific to an antigen species that one seeks to detect. In the ring resonator of the proposed system, light would make multiple passes through the sensing volume, affording greater interaction length and, hence, greater antibody- detection sensitivity.

  8. 3D dosimetry fundamentals: gels and plastics

    NASA Astrophysics Data System (ADS)

    Lepage, M.; Jordan, K.

    2010-11-01

    Many different materials have been developed for 3D radiation dosimetry since the Fricke gel dosimeter was first proposed in 1984. This paper is intended as an entry point into these materials where we provide an overview of the basic principles for the most explored materials. References to appropriate sources are provided such that the reader interested in more details can quickly find relevant information.

  9. Exploratory data analysis groupware for qualitative and quantitative electrophoretic gel analysis over the Internet-WebGel.

    PubMed

    Lemkin, P F; Myrick, J M; Lakshmanan, Y; Shue, M J; Patrick, J L; Hornbeck, P V; Thornwal, G C; Partin, A W

    1999-12-01

    Many scientists use quantitative measurements to compare the presence and amount, of various proteins and nucleotides among series of one- and two-dimensional (1-D and 2-D) electrophoretic gels. These gels are often scanned into digital image files. Gel spots are then quantified using stand-alone analysis software. However, as more research collaborations take place over the Internet, it has become useful to share intermediate quantitative data between researchers. This allows research group members to investigate their data and share their work in progress. We developed a World Wide Web group-accessible software system, WebGel, for interactively exploring qualitative and quantitative differences between electrophoretic gels. Such Internet databases are useful for publishing quantitative data and allow other researchers to explore the data with respect to their own research. Because intermediate results of one user may be shared with their collaborators using WebGel, this form of active data-sharing constitutes a groupware method for enhancing collaborative research. Quantitative and image gel data from a stand-alone gel image processing system are copied to a database accessible on the WebGel Web server. These data are then available for analysis by the WebGel database program residing on that server. Visualization is critical for better understanding of the data. WebGel helps organize labeled gel images into montages of corresponding spots as seen in these different gels. Various views of multiple gel images, including sets of spots, normalization spots, labeled spots, segmented gels, etc. may also be displayed. These displays are active and may be used for performing database operations directly on individual protein spots by simply clicking on them. Corresponding regions between sets of gels may be visually analyzed using Flicker-comparison (Electrophoresis 1997, 18, 122-140) as one of the WebGel methods for qualitative analysis. Quantitative exploratory data

  10. Dielectric properties of gel collected from shark electrosensors

    NASA Astrophysics Data System (ADS)

    Hughes, Mary E.; Brown, Brandon R.; Hutchison, John C.; Murray, Royce W.

    2003-03-01

    To investigate the physical mechanism of the electric sense, we present an initial characterization of the dielectric properties of the glycoprotein gel that fills the electrosensitive organs of marine elasmobranches (sharks, skates, and rays). To ascertain the properties of the gel, low-frequency impedance spectroscopy is used. The impedance data collected from a dialyzed sample show large values of static permittivity and a loss peak corresponding to a long relaxation time (about 1 ms). Impedance measurements of the native (nondialyzed) gel reliable to 0.1 Hz will be presented and compared to the dialyzed gel. Ramifications of the gel's dielectric properties for the electric sense will be explored.

  11. The formation and structure of Olympic gels

    NASA Astrophysics Data System (ADS)

    Fischer, J.; Lang, M.; Sommer, J.-U.

    2015-12-01

    Different methods for creating Olympic gels are analyzed using computer simulations. First ideal reference samples are obtained from freely interpenetrating semi-dilute solutions and melts of cyclic polymers. The distribution of pairwise concatenations per cyclic molecule is given by a Poisson-distribution and can be used to describe the elastic structure of the gels. Several batches of linear chains decorated with different selectively binding groups at their ends are mixed in the "DNA Origami" technique and network formation is realized. While the formation of cyclic molecules follows mean field predictions below overlap of the precursor molecules, an enhanced ring formation above overlap is found that is not explained by mean field arguments. The "progressive construction" method allows to create Olympic gels with a single reaction step from a concentrated mixture of large compressed rings with a low weight fraction of short chains that are below overlap concentration. This method, however, is limited by the difficulty to obtain a sufficiently high degree of polymerization of the large rings.

  12. Micro-size polyacrylamide gel electrophoresis system

    NASA Astrophysics Data System (ADS)

    Hinson, W. G.; Pipkin, J. L.; Anson, J. F.; Casciano, D. A.; Burns, E. R.

    1987-09-01

    The development and characterization of a micro-size two-dimensional polyacrylamide gel electrophoresis system is described. Some of the techniques which have evolved with use of the system are also discussed. This apparatus has unique features which provide advantages over other small scale units. Up to ten first- and second-dimension gels can be processed simultaneously with excellent resolution of protein regions. Consistent reproducibility is possible from protein samples as small as 400 ng and individual protein regions as small as 1 pg can be visualized by silver staining of the two-dimensional gels. Similar sensitivities are achieved in autoradiographs of 3H-labeled proteins extracted from the nuclei of cultured cells. The application of this system in conjunction with flow cytometric examination of nuclear DNA and electrostatic cell sorting of specific cell nuclei to provide homogeneous sample populations, allows subtle variations in isotope incorporation in proteins to be detected; whereas many times in generalized tissue samples these changes are masked. Also, these techniques elucidate the effects of external stimuli (chemicals, drugs, or environment) on protein synthesis and phosphorylation for analyses and comparison. Fabrication drawings are available upon request.

  13. Bucky gel actuators optimization towards haptic applications

    NASA Astrophysics Data System (ADS)

    Bubak, Grzegorz; Ansaldo, Alberto; Ceseracciu, Luca; Hata, Kenji; Ricci, Davide

    2014-03-01

    An ideal plastic actuator for haptic applications should generate a relatively large displacement (minimum 0.2-0.6 mm, force (~50 mN/cm2) and a fast actuation response to the applied voltage. Although many different types of flexible, plastic actuators based on electroactive polymers (EAP) are currently under investigation, the ionic EAPs are the only ones that can be operated at low voltage. This property makes them suitable for applications that require inherently safe actuators. Among the ionic EAPs, bucky gel based actuators are very promising. Bucky gel is a physical gel made by grounding imidazolium ionic liquids with carbon nanotubes, which can then be incorporated in a polymeric composite matrix to prepare the active electrode layers of linear and bending actuators. Anyhow, many conflicting factors have to be balanced to obtain required performance. In order to produce high force a large stiffness is preferable but this limits the displacement. Moreover, the bigger the active electrode the larger the force. However the thicker an actuator is, the slower the charging process becomes (it is diffusion limited). In order to increase the charging speed a thin electrolyte would be desirable, but this increases the probability of pinholes and device failure. In this paper we will present how different approaches in electrolyte and electrode preparation influence actuator performance and properties taking particularly into account the device ionic conductivity (which influences the charging speed) and the electrode surface resistance (which influences both the recruitment of the whole actuator length and its speed).

  14. Gel Electrophoresis of Gold-DNA Nanoconjugates

    DOE PAGESBeta

    Pellegrino, T.; Sperling, R. A.; Alivisatos, A. P.; Parak, W. J.

    2007-01-01

    Gold-DNA conjugates were investigated in detail by a comprehensive gel electrophoresis study based on 1200 gels. A controlled number of single-stranded DNA of different length was attached specifically via thiol-Au bonds to phosphine-stabilized colloidal gold nanoparticles. Alternatively, the surface of the gold particles was saturated with single stranded DNA of different length either specifically via thiol-Au bonds or by nonspecific adsorption. From the experimentally determined electrophoretic mobilities, estimates for the effective diameters of the gold-DNA conjugates were derived by applying two different data treatment approaches. The first method is based on making a calibration curve for the relation between effectivemore » diameters and mobilities with gold nanoparticles of known diameter. The second method is based on Ferguson analysis which uses gold nanoparticles of known diameter as reference database. Our study shows that effective diameters derived from gel electrophoresis measurements are affected with a high error bar as the determined values strongly depend on the method of evaluation, though relative changes in size upon binding of molecules can be detected with high precision. Furthermore, in this study, the specific attachment of DNA via gold-thiol bonds to Au nanoparticles is compared to nonspecific adsorption of DNA. Also, the maximum number of DNA molecules that can be bound per particle was determined.« less

  15. Sol-gel method for encapsulating molecules

    DOEpatents

    Brinker, C. Jeffrey; Ashley, Carol S.; Bhatia, Rimple; Singh, Anup K.

    2002-01-01

    A method for encapsulating organic molecules, and in particular, biomolecules using sol-gel chemistry. A silica sol is prepared from an aqueous alkali metal silicate solution, such as a mixture of silicon dioxide and sodium or potassium oxide in water. The pH is adjusted to a suitably low value to stabilize the sol by minimizing the rate of siloxane condensation, thereby allowing storage stability of the sol prior to gelation. The organic molecules, generally in solution, is then added with the organic molecules being encapsulated in the sol matrix. After aging, either a thin film can be prepared or a gel can be formed with the encapsulated molecules. Depending upon the acid used, pH, and other processing conditions, the gelation time can be from one minute up to several days. In the method of the present invention, no alcohols are generated as by-products during the sol-gel and encapsulation steps. The organic molecules can be added at any desired pH value, where the pH value is generally chosen to achieve the desired reactivity of the organic molecules. The method of the present invention thereby presents a sufficiently mild encapsulation method to retain a significant portion of the activity of the biomolecules, compared with the activity of the biomolecules in free solution.

  16. Fibrillar peptide gels in biotechnology and biomedicine

    PubMed Central

    Jung, Jangwook P.; Gasiorowski, Joshua Z.; Collier, Joel H.

    2012-01-01

    Peptides, peptidomimetics, and peptide derivatives that self-assemble into fibrillar gels have received increasing interest as synthetic extracellular matrices for applications in 3D cell culture and regenerative medicine. Recently, several of these fibrillizing molecules have been functionalized with bioactive components such as cell-binding ligands, degradable sequences, drug-eluting compounds, and chemical modifications for cross-linking, producing gels that can reliably display multiple factors simultaneously. This capacity for incorporating precise levels of many different biological and chemical factors is advantageous given the natural complexity of cell-matrix interactions that many current biomaterial strategies seek to mimic. In this review, recent efforts in the area of fibril-forming peptide materials are described, and advantages of biomaterials containing multiple modular elements are outlined. In addition, a few hurdles and open questions surrounding fibrillar peptide gels are discussed, including issues of the materials’ structural heterogeneity, challenges in fully characterizing the diversity of their self-assembled structures, and incomplete knowledge of how the materials are processed in vivo. PMID:20091870

  17. Novel sol-gel bioactive fibers.

    PubMed

    Oréfice, R L; Hench, L L; Clark, A E; Brennan, A B

    2001-06-15

    Bioactive fibers were produced using a sol-gel method. The rheological properties of two different sol compositions prepared from a mixture of TEOS, phosphorous alkoxide and calcium nitrate, or calcium chloride in a water-ethanol solution, are reported. The sols were extruded through a spinneret to produce continuous 10 microm-diameter fibers. Discontinuous fibers and fibrous mats were prepared by air-spraying the multicomponent sols. The sol-gel fibers were converted to the bioactive fibers by three different thermal treatments at either 600 degrees, 700 degrees, or 900 degrees C for 3 h. SEM, BET, EDX, and FTIR were used to characterize the morphology and structure of the fibers. The BET measured surface area of the fibers sintered at 900 degrees C was 0 m(2)/gm compared to a value of 200 m(2)/gm for a typical sol-gel-derived particle of similar composition. Both the continuous and discontinuous fibers exhibited in vitro bioactivity in a simulated body fluid. PMID:11288073

  18. State of water in gelatin Gels

    SciTech Connect

    Naryshkina, E.P.; Izmailova, V.N.; Polinnyi, A.I.

    1986-03-01

    It has been shown on the basis of the variation of the linewidth of water with time in high-resolution NMR spectra of gelatin gels in D/sub 2/O that there is a decrease in the mobility of the water molecules during the formation of the collagen-like helix in the initial stages of gelation. As the concentration of the protein is increased, the linewidth of the water signal ..delta.. increases, and the spin-spin (T/sub 2/) and spin-lattice (T/sub 1/) relaxation times and the self-diffusion coefficient of the water molecules D /SUB S/ in the fully formed gels of gelatin in H/sub 2/O decreases as a result of the immobilization of water by the gelatin macromolecules and the presence of a three-dimensional gel network. The aforementioned parameters vary as a function of the gelatin concentration in parallel with the value of the Flory-Huggins parameter /CHI/.

  19. Semihumid gels as matrices for laser media

    NASA Astrophysics Data System (ADS)

    Larrue, Denis; Zarzycki, J.; Canva, Michael; Georges, Patrick M.; Brun, Alain

    1992-12-01

    Laser dyes were trapped in SiO2 xerogel host matrices to obtain a solid state dye laser. The evolution of the mechanical properties of two kinds of matrices, 'classic' and 'sono' gels, was followed during drying. A new impregnation process was performed on these xerogels: impregnation with a 'sono' sol. The influence of this treatment on certain physical and mechanical properties of the resulting impregnated gels was studied. The results indicate that impregnation substantially improves hardness, elastic modulus and fracture stress. The samples can then be easily polished to obtain optical quality surfaces and be used in a laser cavity. Moreover, optical properties related to laser emission of these materials such as efficiency, lifetime and longevity are better when the laser dye doped xerogels are impregnated. The organic dye molecule used was sulforhodamine 640, and results were obtained six months after their synthesis, with a pump beam working at a 5 Hz repetition rate with 450 (mu) J/pulse energy level. With the first pump shot on a fixed point of the samples, tunability from 600 to 650 nm, 60 (mu) J threshold, 2600 pump shots lifetime and a 10.5% slope efficiency were achieved using an impregnated 'sono' gel matrix.

  20. Novel configuration of poly(vinylidenedifluoride)-based gel polymer electrolyte for application in lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Fasciani, Chiara; Panero, Stefania; Hassoun, Jusef; Scrosati, Bruno

    2015-10-01

    Herein we propose a novel poly(vinylidene difluoride) (PVdF)-based gel polymer electrolyte (GPE) for application in lithium-ion batteries, LIBs. The GPE is prepared under air as a dry, flexible film and directly gelled during LIB assembly with a conventional liquid organic electrolyte. The dry-gel here originally reported maintains its structural integrity due to the presence of crystallized EC-solvent within its matrix that avoids structural collapse, as demonstrated by TGA analysis. By avoiding the use of controlled atmosphere, the GPE is easy to handle and suitable for roll-to-roll scaling-up, i.e. characteristics missed by the common gel membranes. Scanning Electron Microscopy (SEM) evidences a micrometric polymer network of the dry membrane precursor acting as the support matrix for the gelation. Electrochemical impedance spectroscopy (EIS) measurements and galvanostatic tests suggest a good stability of the lithium electrode/gel electrolyte interface and a satisfactory lithium transference number. Cycling tests of gel-electrolyte-based lithium half-cells using lithium iron phosphate (LiFePO4, LFP) and graphite (C), respectively, as counter electrodes, as well as of a full C/LFP lithium-ion battery confirm the suitability of the GPE developed in this work for application in stable, low cost and environmentally friendly energy storage systems.

  1. Mechano-switchable, luminescent gels derived from salts of a long-chained, fatty-acid gelator.

    PubMed

    Zhang, Mohan; Weiss, Richard G

    2016-07-27

    Stimulus-responsive molecular gel systems, based on metal salts of a luminescent gelator, 9,10-dioxooctadecanoic acid (DODA), are reported. These salts are structurally the simplest metallo-gelators of which we are aware that exhibit controllable mechano-responsive and luminescent properties. Aggregation is more favored by the metal salts than for DODA itself. However, gelation ability differs dramatically depending on the metal ion: whereas the salts with zinc(ii) and calcium(ii) are inefficient gelators, those with nickel(ii) and copper(ii) can gelate various aromatic liquids, alkanes, and long-chained alcohols. Unlike the DODA gels, no aggregation-induced shift in the positions of the emission spectra of the metal salts could be observed as the sols were transformed to their gel phases. Gels of both nickel(ii) and copper(ii) salts in benzonitrile are among the few known examples with crystalline networks and exhibiting thixotropic behavior. However, there are significant differences in their abilities to recover the initial viscoelastic properties. Structural data for the solid and gel states lead us to conclude that differences among the gelating abilities can be attributed principally to the specific nature of interactions of the salts at their head groups. They appear to control the mechanical and emissive properties of the gels as well as whether the initial aggregation of the salts in the sol phases will support the growth of 1D objects that are capable of maintaining strong contacts, leading to 3D networks and gel formation. Overall, the results provide a facile strategy for the design of luminescent materials with controllable mechano-responsiveness by modifying the metal ions within fibrillar assemblies. PMID:27400800

  2. Long-term maintenance antiretroviral therapy with saquinavir hard gel, after voluntary abandonment of successful induction HAART.

    PubMed

    Manfredi, R

    2002-04-01

    HIV-infected patients who voluntarily resorted to an apparently suboptimal drug association including saquinavir hard gel after attaining viral suppression thanks to an antiretroviral regimen based on potent protease inhibitors, had a satisfactory 12-18-month clinical and laboratory outcome. The effects of a potent and sufficiently prolonged induction antiretroviral therapy may be maintained for 12 months or more, especially when the maintenance regimen includes novel nucleoside analogues, and specific genotypical mutations are absent. PMID:12017375

  3. Antimicrobial activity and the mechanism of silver nanoparticle thermosensitive gel

    PubMed Central

    Chen, Meiwan; Yang, Zhiwen; Wu, Hongmei; Pan, Xin; Xie, Xiaobao; Wu, Chuanbin

    2011-01-01

    Purpose The purpose of the present study was to elucidate the antimicrobial activity and mechanism of silver nanoparticles incorporated into thermosensitive gel (S-T-Gel) on Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. Patients and methods This study investigated the growth, permeability, and morphology of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa cells in order to observe the action of S-T-Gel on the membrane structure of these three bacteria. The cell morphology of normal and treated bacteria cells was assessed by transmission electron microscopy (TEM), and the effects of S-T-Gel on genome DNA of bacterial cells were evaluated by agarose gel electrophoresis. Results S-T-Gel showed promising activity against Staphylococcus aureus and moderate activity against Escherichia coli and Pseudomonas aeruginosa. The observation with TEM suggested that S-T-Gel may destroy the structure of bacterial cell membranes in order to enter the bacterial cell. S-T-Gel then condensed DNA and combined and coagulated with the cytoplasm of the damaged bacteria, resulting in the leakage of the cytoplasmic component and the eventual death of these three bacteria. In addition, the analysis of agarose gel electrophoresis demonstrated that S-T-Gel could increase the decomposability of genome DNA. Conclusion These results about promising antimicrobial activity and mechanism of S-T-Gel may be useful for further research and development in in-vivo studies. PMID:22131833

  4. Formulation and evaluation of curcumin gel for topical application.

    PubMed

    Patel, Nikunjana A; Patel, Natvar J; Patel, Rakesh P

    2009-01-01

    The aim of the present investigation was to develop and study topical gel delivery of curcumin for its anti-inflammatory effects. Carbopol 934P (CRB) and hydroxypropylcellulose (HPC) were used for the preparation of gels. The penetration enhancing effect of menthol (0-12.5% w/w) on the percutaneous flux of curcumin through the excised rat epidermis from 2% w/w CRB and HPC gel system was investigated. All the prepared gel formulations were evaluated for various properties such as compatibility, drug content, viscosity, in vitro skin permeation, and anti-inflammatory effect. The drug and polymers compatibility was confirmed by Differential scanning calorimetry and infrared spectroscopy. The percutaneous flux and enhancement ratio of curcumin across rat epidermis was enhanced markedly by the addition of menthol to both types of gel formulations. Both types of developed topical gel formulations were free of skin irritation. In anti-inflammatory studies done by carrageenan induced rat paw oedema method in wistar albino rats, anti-inflammatory effect of CRB, HPC and standard gel formulations were significantly different from control group (P < 0.05) whereas this effect was not significantly different for CRB and HPC gels formulations to that of standard (diclofenac gel) formulation (P > 0.05). CRB gel showed better % inhibition of inflammation as compared to HPC gel. PMID:18821270

  5. Fabrication, modeling and optimization of an ionic polymer gel actuator

    NASA Astrophysics Data System (ADS)

    Jo, Choonghee; Naguib, Hani E.; Kwon, Roy H.

    2011-04-01

    The modeling of the electro-active behavior of ionic polymer gel is studied and the optimum conditions that maximize the deflection of the gel are investigated. The bending deformation of polymer gel under an electric field is formulated by using chemo-electro-mechanical parameters. In the modeling, swelling and shrinking phenomena due to the differences in ion concentration at the boundary between the gel and solution are considered prior to the application of an electric field, and then bending actuation is applied. As the driving force of swelling, shrinking and bending deformation, differential osmotic pressure at the boundary of the gel and solution is considered. From this behavior, the strain or deflection of the gel is calculated. To find the optimum design parameter settings (electric voltage, thickness of gel, concentration of polyion in the gel, ion concentration in the solution, and degree of cross-linking in the gel) for bending deformation, a nonlinear constrained optimization model is formulated. In the optimization model, a bending deflection equation of the gel is used as an objective function, and a range of decision variables and their relationships are used as constraint equations. Also, actuation experiments are conducted using poly(2-acrylamido-2-methylpropane sulfonic acid) (PAMPS) gel and the optimum conditions predicted by the proposed model have been verified by the experiments.

  6. Dynamic light-scattering monitoring of a transient biopolymer gel

    NASA Astrophysics Data System (ADS)

    Kostko, A. F.; Chen, T.; Payne, G. F.; Anisimov, M. A.

    2003-05-01

    We performed dynamic light-scattering (DLS) monitoring and a rheological study to characterize the formation and destruction of a transient (limited lifetime) gel formed from the biopolymers chitosan and gelatin. Gel formation, initiated by the enzyme tyrosinase, is followed by spontaneous gel breakage. Our DLS results demonstrate that this material passes through five stages in which the gel forms, consolidates, “lives”, softens, and eventually breaks. We speculate that the existence of the transient gel is caused by a competition between two processes: a fast-rate chemical reaction leading to formation of a branched-copolymer network and a slow-rate diffusion-like rearrangement of the gelatin branches resulting in eventual gel breakage. Despite a dramatic difference in the characteristic times of the gel formation ( tg) and gel breakage ( tb)-the ratio tb/ tg is of the order 10 3-DLS has revealed an intrinsic monitoring-time symmetry in the formation and destruction of the gel provided that a proper physical choice of the reduced temporal scale is used. In this scale the slow-mode relaxation time for both sides of the process, gel formation and gel destruction, exhibits a power law in the spirit of percolation theory.

  7. Accommodating brightness and exposure levels in densitometry of stained polyacrylamide electrophoresis gels

    SciTech Connect

    Tan, Han Yen; Ng, Tuck Wah; Liew, Oi Wah

    2010-03-20

    Flatbed scanner densitometers can be operated under various illumination and recording exposure levels. In this work, we show that optical density measurement accuracy, sensitivity, and stability of stained polyacrylamide electrophoresis gel densitometry are crucially dependent on these two factors (brightness and exposure level), notwithstanding that the source is monochromatic, spatially uniform, and the measurements are made using an accurately calibrated step wedge in tandem. We further outline a method to accommodate the intensity deviations over a range of illumination and exposure levels in order to maintain sensitivity and repeatability in the computed optical densities. Comparisons were also made with results from a commercial densitometer.

  8. Anion-switchable supramolecular gels for controlling pharmaceutical crystal growth

    NASA Astrophysics Data System (ADS)

    Foster, Jonathan A.; Piepenbrock, Marc-Oliver M.; Lloyd, Gareth O.; Clarke, Nigel; Howard, Judith A. K.; Steed, Jonathan W.

    2010-12-01

    We describe the use of low-molecular-weight supramolecular gels as media for the growth of molecular crystals. Growth of a range of crystals of organic compounds, including pharmaceuticals, was achieved in bis(urea) gels. Low-molecular-weight supramolecular gelators allow access to an unlimited range of solvent systems, in contrast to conventional aqueous gels such as gelatin and agarose. A detailed study of carbamazepine crystal growth in four different bis(urea) gelators, including a metallogelator, is reported. The crystallization of a range of other drug substances, namely sparfloxacin, piroxicam, theophylline, caffeine, ibuprofen, acetaminophen (paracetamol), sulindac and indomethacin, was also achieved in supramolecular gel media without co-crystal formation. In many cases, crystals can be conveniently recovered from the gels by using supramolecular anion-triggered gel dissolution; however, crystals of substances that themselves bind to anions are dissolved by them. Overall, supramolecular gel-phase crystallization offers an extremely versatile new tool in pharmaceutical polymorph screening.

  9. Self-oscillating gels beating like a heart muscle

    PubMed Central

    Yoshida, Ryo

    2012-01-01

    So far stimuli-responsive polymer gels and their application to smart materials have been widely studied. On the other hand, as a novel biomimetic gel, we developed gels with an autonomous self-oscillating function like a heart muscle, which was firstly reported in 1996. We designed the self-oscillating polymers and gels by utilizing the oscillating reaction, called the Belousov-Zhabotinsky (BZ) reaction. The self-oscillating polymer is composed of a poly(N-isopropylacrylamide) network in which the catalyst for the BZ reaction is covalently immobilized. In the presence of the reactants, the polymer gel undergoes spontaneous cyclic swelling–deswelling changes without any on–off switching of external stimuli. Potential applications of the self-oscillating polymers and gels include several kinds of functional material systems, such as bio-mimetic actuators and mass transport surface. In this review, recent progress on the polymer gels is introduced.

  10. Antioxidant effect of green tea on polymer gel dosimeter

    NASA Astrophysics Data System (ADS)

    Samuel, E. J. J.; Sathiyaraj, P.; Deena, T.; Kumar, D. S.

    2015-01-01

    Extract from Green Tea (GTE) acts as an antioxidant in acrylamide based polymer gel dosimeter. In this work, PAGAT gel was used for investigation of antioxidant effect of GTE.PAGAT was called PAGTEG (Polyacrylamide green tea extract gel dosimeter) after adding GTE. Free radicals in water cause pre polymerization of polymer gel before irradiation. Polyphenols from GTE are highly effective to absorb the free radicals in water. THPC is used as an antioxidant in polymer gel dosimeter but here we were replaced it by GTE and investigated its effect by spectrophotometer. GTE added PAGAT samples response was lower compared to THPC added sample. To increase the sensitivity of the PAGTEG, sugar was added. This study confirmed that THPC was a good antioxidant for polymer gel dosimeter. However, GTE also can be used as an antioxidant in polymer gel if use less quantity (GTE) and add sugar as sensitivity enhancer.

  11. Responsive Gel-Gel Phase Transitions in Artificially Engineered Protein Hydrogels

    NASA Astrophysics Data System (ADS)

    Olsen, B. D.

    2012-02-01

    Artificially engineered protein hydrogels provide an attractive platform for biomedical materials due to their similarity to components of the native extracellular matrix. Engineering responsive transitions between shear-thinning and tough gel phases in these materials could potentially enable gels that are both shear-thinning and tough to be produced as novel injectable biomaterials. To engineer a gel with such transitions, a triblock copolymer with thermoresponsive polymer endblocks and an artificially engineered protein gel midblock is designed. Temperature is used to trigger a transition from a single network protein hydrogel phase to a double network phase with both protein and block copolymer networks present at different length scales. The thermodynamics of network formation and resulting structural changes are established using small-angle scattering, birefringence, and dynamic scanning calorimetry. The formation of the second network is shown to produce a large, nonlinear increase in the elastic modulus as well as enhancements in creep compliance and toughness. Although the gels show yielding behavior in both the single and double network regimes, a qualitative change in the deformation mechanism is observed due to the structural changes.

  12. Characterization of silica gel prepared by using sol-gel process

    NASA Astrophysics Data System (ADS)

    Besbes, M.; Fakhfakh, N.; Benzina, M.

    2009-11-01

    We studied the preparation of silica gels from sodium silicate solution mixed with hydrochloric acid by sol-gel process. The obtained gel is washed with water to obtain a 'hydrogel'. The immersion of the last one in alcohol, gives an 'alcogel'. A Hoke D6 experimental design was followed in order to limit the number of tests. pH and the silica concentration represent the most significant factors which control the obtaining of a significant specific surface and thus a great capacity of adsorption. A second order polynomial model was adopted in order to represent the results in the form of three-dimensional surfaces. These results are also topographically illustrated as isoresponses lines. The results showed that the pH effect is more significant than the silica concentration one. We obtained gels with great microporosity and presenting specific surfaces of 657 m2.g-1 when pH is equal to 2. The prepared gel without alcohol presents interesting characteristics for a potential industrial use since its production cost is lowest and has a high specific surface.

  13. Time-dependent gel to gel transformation of a peptide based supramolecular gelator.

    PubMed

    Baral, Abhishek; Basak, Shibaji; Basu, Kingshuk; Dehsorkhi, Ashkan; Hamley, Ian W; Banerjee, Arindam

    2015-06-28

    A dipeptide with a long fatty acid chain at its N-terminus gives hydrogels in phosphate buffer in the pH range 7.0-8.5. The hydrogel with a gelator concentration of 0.45% (w/v) at pH 7.46 (physiological pH) provides a very good platform to study dynamic changes within a supramolecular framework as it exhibits remarkable change in its appearance with time. Interestingly, the first formed transparent hydrogel gradually transforms into a turbid gel within 2 days. These two forms of the hydrogel have been thoroughly investigated by using small angle X-ray scattering (SAXS), powder X-ray diffraction (PXRD), field emission scanning electron microscopic (FE-SEM) and high-resolution transmission electron microscopic (HR-TEM) imaging, FT-IR and rheometric analyses. The SAXS and low angle PXRD studies substantiate different packing arrangements for the gelator molecules for these two different gel states (the freshly prepared and the aged hydrogel). Moreover, rheological studies of these two gels reveal that the aged gel is stiffer than the freshly prepared gel. PMID:26016677

  14. Ionogel Electrolytes through Sol-Gel Processing

    NASA Astrophysics Data System (ADS)

    Horowitz, Ariel I.

    Electrical energy needs have intensified due to the ubiquity of personal electronics, the decarbonization of energy services through electrification, and the use of intermittent renewable energy sources. Despite developments in mechanical and thermal methods, electrochemical technologies are the most convenient and effective means of storing electrical energy. These technologies include both electrochemical cells, commonly called batteries, and electrochemical double-layer capacitors, or "supercapacitors", which store energy electrostatically. Both device types require an ion-conducting electrolyte. Current devices use solutions of complex salts in organic solvents, leading to both toxicity and flammability concerns. These drawbacks can be avoided by replacing conventional electrolytes with room-temperature molten salts, known as ionic liquids (ILs). ILs are non-volatile, non-flammable, and offer high conductivity and good electrochemical stability. Device mass can be reduced by combining ILs with a solid scaffold material to form an "ionogel," further improving performance metrics. In this work, sol-gel chemistry is explored as a means of forming ionogel electrolytes. Sol-gel chemistry is a solution-based, industrially-relevant, well-studied technique by which solids such as silica can be formed in situ. Previous works used a simple acid-catalyzed sol-gel reaction to create brittle, glassy ionogels. Here, both the range of products that can be accomplished through sol-gel processing and the understanding of interactions between ILs and the sol-gel reaction network are greatly expanded. This work introduces novel ionogel materials, including soft and compliant silica-supported ionogels and PDMS-supported ionogels. The impacts of the reactive formulation, IL identity, and casting time are detailed. It is demonstrated that variations in formulation can lead to rapid gelation and open pore structures in the silica scaffold or slow gelation and more dense silica

  15. The biophysical properties of Basal lamina gels depend on the biochemical composition of the gel.

    PubMed

    Arends, Fabienna; Nowald, Constantin; Pflieger, Kerstin; Boettcher, Kathrin; Zahler, Stefan; Lieleg, Oliver

    2015-01-01

    The migration of cells within a three-dimensional extracellular matrix (ECM) depends sensitively on the biochemical and biophysical properties of the matrix. An example for a biological ECM is given by reconstituted basal lamina gels purified from the Engelbreth-Holm-Swarm sarcoma of mice. Here, we compare four different commercial variants of this ECM, which have all been purified according to the same protocol. Nevertheless, in those gels, we detect strong differences in the migration behavior of leukocyte cells as well as in the Brownian motion of nanoparticles. We show that these differences correlate with the mechanical properties and the microarchitecture of the gels which in turn arise from small variations in their biochemical composition. PMID:25689062

  16. The Biophysical Properties of Basal Lamina Gels Depend on the Biochemical Composition of the Gel

    PubMed Central

    Pflieger, Kerstin; Boettcher, Kathrin; Zahler, Stefan; Lieleg, Oliver

    2015-01-01

    The migration of cells within a three-dimensional extracellular matrix (ECM) depends sensitively on the biochemical and biophysical properties of the matrix. An example for a biological ECM is given by reconstituted basal lamina gels purified from the Engelbreth-Holm-Swarm sarcoma of mice. Here, we compare four different commercial variants of this ECM, which have all been purified according to the same protocol. Nevertheless, in those gels, we detect strong differences in the migration behavior of leukocyte cells as well as in the Brownian motion of nanoparticles. We show that these differences correlate with the mechanical properties and the microarchitecture of the gels which in turn arise from small variations in their biochemical composition. PMID:25689062

  17. Investigation of the Peroxovanadate Sol-Gel Process and Characterization of the Gels

    SciTech Connect

    Craig Joseph Fontenot

    2001-12-31

    In general, the peroxovanadate solution sol-gel process can be thought of as consisting of two parts: (1) the decomposition of the peroxo species and (2) cation hydrolysis leading to gelation. By controlling the synthesis conditions, both layered and amorphous compounds can be created. However, the type of water coordination observed in these gels was found to be identical no matter what the long-range order. The current work clarified many of the discrepancies found in the literature and offered much new valuable information. Highlights include the types of vanadium environments present at various stages of hydration, the role of adsorbed water, oxygen exchange from adsorbed water into the gel sites, and the ability to create metastable VMoO solid solution phases. These results could have a variety of impacts on future catalysis research.

  18. System availability management technique for reliability and maintainability analysis

    NASA Technical Reports Server (NTRS)

    Davenport, G. K.

    1970-01-01

    Method for total system availability analysis is based on numerical prediction of the reliability, maintainability, and availability of each function system. It incorporates these functional-system estimates into an overall mathematical model.

  19. 48 CFR 1306.202 - Establishing or maintaining alternative sources.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... OF COMMERCE COMPETITION AND ACQUISITION PLANNING COMPETITION REQUIREMENTS Full and Open Competition... exclude a source from a contract action in order to establish or maintain an alternate source is set...

  20. 48 CFR 1306.202 - Establishing or maintaining alternative sources.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... OF COMMERCE COMPETITION AND ACQUISITION PLANNING COMPETITION REQUIREMENTS Full and Open Competition... exclude a source from a contract action in order to establish or maintain an alternate source is set...