Shaposhnikov, A A; Kuznetsova, Rimma T; Kopylova, T N; Maier, G V; Tel'minov, E N; Pavich, T A; Arabei, S M
2004-08-31
The absorption and emission properties of eight organic compounds in silica gel matrices of different chemical compositions and different types (bulk samples and thin films) are studied upon excitation by a XeCl laser and the second harmonic of a Nd:YAG laser. The mechanisms of the laser-induced changes in the spectral parameters of molecules in silica gel matrices are discussed and the photostability of the laser dyes in silica gel films is estimated. (active media)
Maize arabinoxylan gels as protein delivery matrices.
Berlanga-Reyes, Claudia M; Carvajal-Millán, Elizabeth; Lizardi-Mendoza, Jaime; Rascón-Chu, Agustin; Marquez-Escalante, Jorge A; Martínez-López, Ana Luisa
2009-04-08
The laccase induced gelation of maize bran arabinoxylans at 2.5% (w/v) in the presence of insulin or beta-lactoglobulin at 0.1% (w/v) was investigated. Insulin and beta-lacto-globulin did not modify either the gel elasticity (9 Pa) or the cross-links content (0.03 and 0.015 microg di- and triferulic acids/mg arabinoxylan, respectively). The protein release capability of the gel was also investigated. The rate of protein release from gels was dependent on the protein molecular weight. The apparent diffusion coefficient was 0.99 x 10(-7) and 0.79 x 10(-7) cm(2)/s for insulin (5 kDa) and beta-lactoglobulin (18 kDa), respectively. The results suggest that maize bran arabinoxylan gels can be potential candidates for the controlled release of proteins.
Fibroblast migration in fibrin gel matrices.
Brown, L. F.; Lanir, N.; McDonagh, J.; Tognazzi, K.; Dvorak, A. M.; Dvorak, H. F.
1993-01-01
In healing wounds and many solid tumors, locally increased microvascular permeability results in extravasation of fibrinogen and its extravascular coagulation to form a fibrin gel, with concomitant covalent cross-linking of fibrin by factor XIIIa. Subsequently, inflammatory cells, fibroblasts, and endothelial cells migrate into the gel and organize it into granulation tissue and later into mature collagenous connective tissue. To gain insight into some of the cell migration events associated with these processes, we developed a quantitative in vitro assay that permits the study of fibroblast migration in fibrin gels. Early passage human or rat fibroblasts were allowed to attach to tissue culture dishes and then were overlaid with a thin layer of fibrinogen that was clotted with thrombin. Fibroblasts began to migrate upwards into the fibrin within 24 hours and their numbers and the distance migrated were quantified over several days. The extent of fibroblast migration was affected importantly by the nature of the fibrin clot. Fibroblasts migrated optimally into gels prepared from fibrinogen at concentrations of -3 mg/ml; ie, near normal plasma fibrinogen levels. Migration was greatly enhanced by extensive cross-linking of the fibrin alpha-chains by factor XIIIa, as occurs when clotting takes place in vivo. When fibrinogen was clotted in Dulbecco's modified Eagle's medium, gamma-chains were cross-linked, but alpha-chain cross-linking was strikingly inhibited, and fibroblasts migrated poorly. Gels prepared from factor XIII-depleted fibrinogen exhibited neither alpha-nor gamma-chain cross-linking and did not support fibroblast migration. Further purification of fibrinogen by anion exchange high pressure liquid chromatography depleted fibrinogen of fibronectin, plasminogen, and other impurities; this purified fibrinogen clotted to form fibrin gels that supported reproducible fibroblast migration. Images Figure 1 Figure 2 Figure 4 Figure 6 PMID:8424460
Optical detection of parasitic protozoa in sol-gel matrices
NASA Astrophysics Data System (ADS)
Livage, Jacques; Barreau, J. Y.; Da Costa, J. M.; Desportes, I.
1994-10-01
Whole cell parasitic protozoa have been entrapped within sol-gel porous silica matrices. Stationary phase promastigote cells of Leishmania donovani infantum are mixed with a silica sol before gelation occurs. They remain trapped within the growing oxide network and their cellular organization appears to be well preserved. Moreover protozoa retain their antigenic properties in the porous gel. They are still able to detect parasite specific antibodies in serum samples from infected patients via an enzyme linked immunosorbent assay (ELISA). Antigen- antibody associations occurring in the gel are optically detected via the reactions of a peroxidase conjugate with ortho-phenylenediamine leading to the formation of a yellow coloration. A clear-cut difference in optical density is measured between positive and negative sera. Such an entrapment of antigenic species into porous sol-gel matrices avoids the main problems due to non specific binding and could be advantageously used in diagnostic kits.
Examination of the structure of sol-gel derived matrices for optoelectronic sensors
NASA Astrophysics Data System (ADS)
Ulatowska, Agnieszka; Podbielska, Halina; Lechna, Monika; Grzegorzewski, Bronisław
2001-06-01
Sol-gel technology was used to produce glass-like materials doped with different compounds. The sol-gel matrices were prepared on the way of acid hydrolysis. Two types of materials in the form of thin layers were examined: sol-gel bulk type (type I) and thin film type (type II). The structure was visualized by means of a light microscope. The microscopic images were digitized and their luminances were calculated. The thin film type (type II) matrices were investigated also by means of small-angle light scattering. The material properties with dopants such as albumin, ruthenium complex and osmium tetraoxide were examined. The type II matrices showed more homogeneous structure. Lower scattering in doped materials than in the pure matrices was observed.
Slow Release Of Reagent Chemicals From Gel Matrices
NASA Technical Reports Server (NTRS)
Debnam, William J.; Barber, Patrick G.; Coleman, James
1988-01-01
Procedure developed for slow release of reagent chemicals into solutions. Simple and inexpensive and not subject to failure of equipment. Use of toothpaste-type tube or pump dispenser conceivably provides more controlled technique for storage and dispensation of gel matrix. Possible uses include controlled, slow release of reagents in chemical reactions, crystal growth, space-flight experiments, and preformed gel medications from packets.
Sol-gel matrices for direct colorimetric detection of analytes
Charych, Deborah H.; Sasaki, Darryl; Yamanaka, Stacey
2000-01-01
The present invention relates to methods and compositions for the direct detection of analytes using color changes that occur in immobilized biopolymeric material in response to selective binding of analytes to their surface. In particular, the present invention provides methods and compositions related to the encapsulation of biopolymeric material into metal oxide glass using the sol-gel method.
Sol-Gel Matrices For Direct Colorimetric Detection Of Analytes
Charych, Deborah H.; Sasaki, Darryl; Yamanaka, Stacey
2002-11-26
The present invention relates to methods and compositions for the direct detection of analytes using color changes that occur in immobilized biopolymeric material in response to selective binding of analytes to their surface. In particular, the present invention provides methods and compositions related to the encapsulation of biopolymeric material into metal oxide glass using the sol-gel method.
GRIN optics with transition elements in gel-silica matrices
NASA Astrophysics Data System (ADS)
Kunetz, James M.; West, Jon K.; Hench, Larry L.
1992-12-01
Sol-gel technology is providing a viable alternative path towards developing doped optical components via impregnation of Type VI gel silica using a vapor or liquid phase. Past work presented an optical technique for determining quantitative mass transport properties of Cr3+ ions within the water filled porous phase of Type VI silica. Ion influx is measured by integrating the strong absorption bands produced by the chromium in the visible region. Diffusion coefficients are determined for an array of pore properties (radius, volume, surface area) as well as solution concentrations. Diffusion coefficients are calculated to be 2.0 X 10-8 cm2/sec for the most restricted case and approach 1.6 X 10-6 cm2/sec, the bulk liquid diffusion coefficient, as the ratio of diffusing solute diameter to the pore diameter decreases. Final chromium distributions are determined using electron microprobe x-ray. Higher chromium distributions are found on surfaces of the gels from which solvent is restricted from evaporating. Sample geometries affect the percent change of concentration across the cross-section.
Embedding Luminescent Nanocrystals in Silica Sol-Gel Matrices
2006-01-01
ASAP Article. [18] Li, J. J.; Wang, Y. A.; Guo, W .; Keay , J. C.; Mishima, T. D.; Johnson, M. B.; Peng, X., J. Am. Chem. Soc.; 2003; 125(41...Guo, W . Z; Keay , J. C.; Mishima, T. D.; Johnson, M. B.; Peng, X. G.; J. Am. Chem. Soc., 2003, 125, 12567. [31] Brinker, C. J.; Scherer, G. W .; J...weeks, any slight inconsistencies in this timeline can change outcome. Also, when a gel is formed, it appears to go through ‘cycles’ of bright and
Chow, Keat Theng; Chan, Lai Wah; Heng, Paul W S
2008-08-01
This study reports the characterization of spreadability of nonaqueous ethylcellulose (EC) gel matrices intended for topical drug delivery using a newly developed method based on dynamic contact angle. EC solutions were prepared using three grades of EC and propylene glycol dicaprylate/dicaprate. Dynamic contact angles of sessile drops of EC solutions on silicone elastomer were measured using a dynamic contact angle analyzer equipped with axisymmetric drop shape analysis-profile. Roughness of silicone elastomer, viscosity of EC solutions and compressibility of semisolid EC gels were determined by the atomic force microscope, cone-and-plate rheometer and tensile tester, respectively. The silicone elastomer employed as a substrate was demonstrated to have similar hydrophilic/lipophilic properties as the human skin. Spreadability of EC solutions was dependent on EC concentration, polymeric chain length and polydispersity. EC gel spreadability was governed by viscosity and the extent of gel-substrate interaction. From the apparent contact angle values, most EC gel formulations tested were found to be moderately spreadable. Linear correlation observed between spreading parameter and compressibility of EC gel verified the applicability of dynamic contact angle to characterize EC gel spreadability. Thus, the feasibility of employing dynamic contact angle as an alternative technique to measure gel spreadability was demonstrated. The spreadability demonstrated by EC gel would facilitate application on the skin indicating its potential usefulness as a topical dosage form.
Minimally Adhesive, Advanced Non-toxic Coatings of Dendrimeric Catalysts in Sol-Gel Matrices
2015-10-19
Catalysts in Sol-Gel Matrices 5a. CONTRACT NUMBER 5b. GRANT NUMBER N00014-09-1-0217 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Detty, Michael R. 5d...SUPPLEMENTARY NOTES 14. ABSTRACT We have developed new xerogel coatings with organochalcogenide or metal oxide catalysts for the activation of...hydrogen peroxide as anti-fouling, fouling-release surfaces. The catalysts perform more efficiently when covalently attached to the xerogel framework
Titanium (IV) sol-gel chemistry in varied gravity environments
NASA Astrophysics Data System (ADS)
Hales, Matthew; Martens, Wayde; Steinberg, Theodore
Sol-gel synthesis in reduced gravity is a relatively new topic in the literature and further inves-tigation is essential to realise its potential and application to other sol-gel systems. The sol-gel technique has been successfully applied to the synthesis of silica systems of varying porosity for many diverse applications [1-5]. It is proposed that current methods for the synthesis of silica sol-gels in reduced gravity may be applied to titanium sol-gel processing in order to enhance desirable physical and chemical characteristics of the final materials. The physical and chemical formation mechanisms for titanium alkoxide based sol-gels, to date, is not fully understood. However, various authors [6-9] have described potential methods to control the hydrolysis and condensation reactions of titanium alkoxides through the use of chemical inhibitors. A preliminary study of the reaction kinetics of titanium alkoxide sol-gel reaction in normal gravity was undertaken in order to determine reactant mixtures suitable for further testing under varied gravity conditions of limited duration. Through the use of 1H Nuclear Magnetic Resonance spectroscopy (NMR) for structural analysis of precursor materials, Ultra-Violet-Visible spectroscopy (UV-VIS) and viscosity measurements, it was demonstrated that not only could the rate of the chemical reaction could be controlled, but directed linear chain growth within the resulting gel structure was achievable through the use of increased inhibitor concentrations. Two unique test systems have been fabricated to study the effects of varied gravity (reduced, normal, high) on the formation of titanium sol-gels. Whilst the first system is to be used in conjunction with the recently commissioned drop tower facility at Queensland University of Technology in Brisbane, Australia to produce reduced gravity conditions. The second system is a centrifuge capable of providing high gravity environments of up to 70 G's for extended periods of time
Permeability of starch gel matrices and select films to solvent vapors.
Glenn, Gregory M; Klamczynski, Artur P; Ludvik, Charles; Shey, Justin; Imam, Syed H; Chiou, Bor-Sen; McHugh, Tara; DeGrandi-Hoffman, Gloria; Orts, William; Wood, Delilah; Offeman, Rick
2006-05-03
Volatile agrochemicals such as 2-heptanone have potential in safely and effectively controlling important agricultural pests provided that they are properly delivered. The present study reports the permeability of starch gel matrices and various coatings, some of which are agricultural-based, that could be used in controlled release devices. Low-density, microcellular starch foam was made from wheat, Dent corn, and high amylose corn starches. The foam density ranged from 0.14 to 0.34 g/cm3, the pore volume ranged from 74 to 89%, and the loading capacity ranged from 2.3 to 7.2 times the foam weight. The compressive properties of the foam were not markedly affected by saturating the pore volume with silicone oil. The vapor transmission rate (VTR) and vapor permeability (VP) were measured in dry, porous starch foam and silicone-saturated starch gels. VTR values were highest in foam samples containing solvents with high vapor pressures. Silicone oil-saturated gels had lower VTR and VP values as compared to the dry foam. However, the silicone oil gel did not markedly reduce the VP for 2-heptanone and an additional vapor barrier or coating was needed to adequately reduce the evaporation rate. The VP of films of beeswax, paraffin, ethylene vinyl alcohol, a fruit film, and a laminate comprised of beeswax and fruit film was measured. The fruit film had a relatively high VP for polar solvents and a very low VP for nonpolar solvents. The laminate film provided a low VP for polar and nonpolar solvents. Perforating the fruit film portion of the laminate provided a method of attaining the target flux rate of 2-heptanone. The results demonstrate that the vapor flux rate of biologically active solvents can be controlled using agricultural materials.
Tritt-Goc, Jadwiga; Kowalczuk, Joanna; Pislewski, Narcyz
2003-11-01
Magnetic resonance imaging was used to study the diffusion of a water solution of hydrochloric acid into hypromellose (hydroxypropylmethylcellulose) matrices. Spatially resolved information was obtained about the self-diffusion coefficient and spin-spin relaxation time of solvent protons in the gel layer of hypromellose matrices loaded with different amounts of tetracycline hydrochloride. The data showed the influence of the drug concentration on the diffusion and spin-spin relaxation. Higher drug concentrations in the hypromellose matrix led to greater swelling of the matrix and faster diffusion of the water molecules inside the gel layer of the polymer. The observed differences between the radial and axial diffusion were interpreted in terms of the stresses imposed in the axial direction during the compression of the samples. The spin-spin and diffusion profiles indicated that the diffusion of a water solution of hydrochloric acid into hypromellose, pure and loaded with different amounts of tetracycline hydrochloride, was characterized as a Case II mechanism.
Gopishankar, N; Watanabe, Yoichi; Subbiah, Vivekanandhan
2011-01-31
One of treatment planning techniques with Leksell GammaPlan (LGP) for Gamma Knife stereotactic radiosurgery (GKSRS) uses multiple matrices with multiple dose prescriptions. Computational complexity increases when shots are placed in multiple matrices with different grid sizes. Hence, the experimental validation of LGP calculated dose distributions is needed for those cases. For the current study, we used BANG3 polymer gel contained in a head-sized glass bottle to simulate the entire treatment process of GKSRS. A treatment plan with three 18 mm shots and one 8 mm shot in separate matrices was created with LGP. The prescribed maximum dose was 8 Gy to three shots and 16 Gy to one of the 18 mm shots. The 3D dose distribution recorded in the gel dosimeter was read using a Siemens 3T MRI scanner. The scanning parameters of a CPMG pulse sequence with 32 equidistant echoes were as follows: TR = 7 s, echo step = 13.6 ms, field-of-view = 256 mm × 256 mm, and pixel size = 1 mm × 1 mm. Interleaved acquisition mode was used to obtain 15 to 45 2-mm-thick slices. Using a calibration relationship between absorbed dose and the spin-spin relaxation rate (R2), we converted R2 images to dose images. MATLAB-based in-house programs were used for R2 estimation and dose comparison. Gamma-index analysis for the 3D data showed gamma values less than unity for 86% of the voxels. Through this study we accomplished the first application of polymer gel dosimetry for a true comparison between measured 3D dose distributions and LGP calculations for plans using multiple matrices for multiple targets.
Valentín-Vargas, Alexis; Chorover, Jon; Maier, Raina M.
2013-01-01
The Standard-Based Polynomial Interpolation (SBPIn) method is a new simple three-step protocol proposed to address common gel-to-gel variations for the comparison of sample profiles across multiple DGGE gels. The advantages of this method include no requirement for additional software or modification of the standard DGGE protocol. PMID:23234884
NASA Astrophysics Data System (ADS)
Vyagin, O. G.; Bespalova, I. I.; Masalov, A. A.; Zelenskaya, O. V.; Tarasov, V. A.; Malyukin, Yu. V.
2014-11-01
Luminescent composites based on SiO2 matrices synthesized using the sol-gel method and organic scintillators PPO and o-POPOP are produced, and their optical, luminescent, and scintillation characteristics are studied. It is shown that these composites generate an intense photoluminescence signal, possess a nanosecond decay time, and have a transparency in the range of 400-700 nm of no less than 70%. The absolute light output during excitation by α radiation with an energy of 5.46 MeV is 4400-5100 photon/MeV, and the amplitude resolution is 27-32%.
Mechanosensing of cells in 3D gel matrices based on natural and synthetic materials.
Shan, Jieling; Chi, Qingjia; Wang, Hongbing; Huang, Qiping; Yang, Li; Yu, Guanglei; Zou, Xiaobing
2014-11-01
Cells in vivo typically are found in 3D matrices, the mechanical stiffness of which is important to the cell and tissue-scale biological processes. Although it is well characterized that as to how cells sense matrix stiffness in 2D substrates, the scenario in 3D matrices needs to be explored. Thus, materials that can mimic native 3D environments and possess wide, physiologically relevant elasticity are highly desirable. Natural polymer-based materials and synthetic hydrogels could provide an better 3D platforms to investigate the mechano-response of cells with stiffness comparable to their native environments. However, the limited stiffness range together with interdependence of matrix stiffness and adhesive ligand density are inherent in many kinds of materials, and hinder efforts to demonstrate the true effects contributed by matrix stiffness. These problems have been addressed by the recently emerging exquisitely designed materials based on native matrix components, designer matrices, and synthetic polymers. In this review, a variety of materials with a wide stiffness range that mimic the mechanical environment of native 3D matrices and the independent affection of stiffness for cellular behavior and tissue-level processes are discussed.
Strength of interactions between immobilized dye molecules and sol-gel matrices.
Ismail, Fanya; Schoenleber, Monika; Mansour, Rolan; Bastani, Behnam; Fielden, Peter; Goddard, Nicholas J
2011-02-21
In this paper we present a new theory to re-examine the immobilization technique of dye doped sol-gel films, define the strength and types of possible bonds between the immobilized molecule and sol-gel glass, and show that the immobilized molecule is not free inside the pores as was previously thought. Immobilizing three different pH sensitive dyes with different size and functional groups inside the same sol-gel films revealed important information about the nature of the interaction between the doped molecule and the sol-gel matrix. The samples were characterized by means of ultraviolet-visible spectrophotometer (UV-VIS), thermal gravimetric analysis (TGA), mercury porosimetry (MP), nuclear magnetic resonance spectroscopy ((29)Si NMR) and field-emission environmental scanning electron microscopy (ESEM-FEG). It was found that the doped molecule itself has a great effect on the strength and types of the bonds. A number of factors were identified, such as number and types of the functional groups, overall charge, size, pK(a) and number of the silanol groups which surround the immobilized molecule. These results were confirmed by the successful immobilization of bromocresol green (BCG) after a completely polymerized sol-gel was made. The sol-gel consisted of 50% tetraethoxysilane (TEOS) and 50% methyltriethoxysilane (MTEOS) (w/w). Moreover, the effect of the immobilized molecule on the structure of the sol-gel was studied by means of a leaky waveguide (LW) mode for doped films made before and after polymerization of the sol-gel.
Pectin-silica gels as matrices for controlled drug release in gastrointestinal tract.
Vityazev, Fedor V; Fedyuneva, Maiia I; Golovchenko, Victoria V; Patova, Olga A; Ipatova, Elena U; Durnev, Eugene A; Martinson, Ekaterina A; Litvinets, Sergey G
2017-02-10
The synthesis of pectin-silica gels for controlled drug release in gastrointestinal tract (GIT) using low methoxyl (LM) and high methoxy (HM) pectins and tetraethoxysilane (TEOS) as precursor is described. The FTIR spectra of the pectin-silica gels show intense absorption bands at 1246cm(-1) and 802cm(-1) corresponding to the vibrations COSi bonds, which absent in the FTIR spectra of the native pectins that indicate the formation covalent bond between silica and pectin macromolecules in the pectin-silica gels. Pectin-TEOS, pectin-Ca-TEOS and pectin-TEOS-Ca beads with mesalazine are synthesized by different combinations of sol-gel method using TEOS and ionotropic gelation method using calcium chloride. The best resistant of pectin-TEOS and pectin-Ca-TEOS beads during incubation in simulated gastric fluid for 2h and subsequently in simulated intestinal fluids for 18h is indicated. Pectin-TEOS beads are characterized by higher encapsulation efficiency (to 28%) than pectin-Ca-TEOS beads (to 16%). The drug release of pectin-silica beads in simulated GIT occurs gradually up to 80% and is directly dependent on the hardness of the beads. The surface morphology of beads is shown. The use of pectin-silica beads is promising with regard to the development of controlled release of drug formulations.
Mason, Laura Michelle; Campiñez, María Dolores; Pygall, Samuel R; Burley, Jonathan C; Gupta, Pranav; Storey, David E; Caraballo, Isidoro; Melia, Colin D
2015-08-01
Percolation theory has been used for several years in the design of HPMC hydrophilic matrices. This theory predicts that a minimum threshold content of polymer is required to provide extended release of drug, and that matrices with a lower polymer content will exhibit more rapid drug release as a result of percolation pathways facilitating the faster penetration of the aqueous medium. At present, percolation thresholds in HPMC matrices have been estimated solely through the mathematical modelling of dissolution data. This paper examines whether they can be also identified in a novel way: through the use of confocal laser scanning fluorescence microscopy (CLSM) to observe the morphology of the emerging gel layer during the initial period of polymer hydration and early gel formation at the matrix surface. In this study, matrices have been prepared with a polymer content of 5-30% w/w HPMC 2208 (Methocel K4M), with a mix of other excipients (a soluble drug (caffeine), lactose, microcrystalline cellulose and magnesium stearate) to provide a typical industrially realistic formulation. Dissolution studies, undertaken in water using USP apparatus 2 (paddle) at 50rpm, provided data for the calculation of the percolation threshold through relating dissolution kinetic parameters to the excipient volumetric fraction of the dry matrix. The HPMC percolation threshold estimated this way was found to be 12.8% v/v, which was equivalent to a matrix polymer content of 11.5% w/w. The pattern of polymer hydration and gel layer growth during early gel layer formation was examined by confocal laser scanning fluorescence microscopy (CLSM). Clear differences in gel layer formation were observed. At polymer contents above the estimated threshold a continuous gel layer was formed within 15min, whereas matrices with polymer contents below the threshold were characterised by irregular gel layer formation with little evidence of HPMC particle coalescence. According to percolation theory, this
NASA Astrophysics Data System (ADS)
Kwon, Hyeog-Chan
Fiber optic chemical sensors (FOCS) for oxygen, dissolved oxygen (DO), and dissolved CO2 sensing using thin films of fluorophores encapsulated in sol-gel matrices were made and tested. The DO/O2 sensor used ruthenium(II) tris(4,7-diphenyl-1,10-phenanthroline) perchlorate (Ru(Ph 2Phen)Cl2) as the oxygen sensitive fluorophore and methyltrimethoxysilane (MTMS) sol-gel as the encapsulating matrix material. For the DCO2 sensor, 8-hydroxy-1,3,6-pyrenetrisulfonic acid trisodium salt (HPTS) co-doped with sodium bicarbonate was used as the DCO2 sensitive fluorophore-chemical system and diisobutoxy-alumino triethoxysilane (ASE) sol-gel was used as the encapsulating matrix material. It was found that oxygen quenches the excited state Ru(Ph2Phen)Cl 2 by diffusing through the MTMS matrix. Continuous excitation of Ru(Ph 2Phen)Cl2 during MTMS drying resulted in long, single exponential lifetimes of the metal complex and increased sensor sensitivity. When the sensor was field tested, it was found to have an excellent match compared to conventional titration method for determining dissolved oxygen concentrations and had fast response times. It was determined that this sensor measured the vapor pressure of oxygen rather than the absolute concentration of dissolved oxygen. For DCO2 sensing, it was found that the dynamic response of the senor could be tuned by varying the HPTS to NaHCO3 ratios. The sensor had fast response times compared to other fiber optic DCO 2 sensors reported which typically have response times of minutes.
NASA Astrophysics Data System (ADS)
Pokrass, Mariana; Burshtein, Zeev; Bar, Galit; Gvishi, Raz
2014-09-01
Carbon-nanotubes (CNT) are fascinating compounds, exhibiting exceptional electrical, thermal conductivity, mechanical strength, and nonlinear optical (NLO) properties. Their unique structures involve large π-π* electronic clouds. The energy level schemes thus created allow many electronic transitions between the ground and the excited states. The present work involves CNT-doped hybrid organic-inorganic glass composites prepared by a Fast-sol-gel method. Such composite glasses solidify without shrinkage or crack formation, and exhibit promising properties as optical devices. In this work we have studied nonlinear optical and electrical conductivity properties. The CNT composite glasses exhibited enhanced absorption at 532 nm, and saturable absorption at 1064 nm. The enhanced absorption at 532 was attributed to 2-photon absorption; saturable absorption was attributed to depletion of the absorbing ground-state, and was analyzed using the modified Frantz-Nodvik equation. Absorption cross-sections were extracted for the saturable absorption phenomenon. Such CNT composites glasses may be used as "optical limiting" filters in lasers near 532 nm, or as saturable absorbing filters for passive laser Q-switching near 1064 nm. The CNT composites electrical conductivity was studied as a function of the CNT concentration and modeled by a percolation theory. The maximal measured conductivity was σ ≍10-3 (Ωcm)-1 for the CNT composites, representing a conductivity increase of at least 12 orders of magnitude compared to that of pure silica. A quite low percolation threshold was obtained, φc = 0.22 wt.% CNT. Electrostatic Force Microscopy (EFM) and Conductive mode Atomic Force Microscopy (C-AFM) studies revealed that the conductivity occurs at the micro-level among the CNTs dispersed in the matrix.
Liu, Dean-Mo; Chen, I-Wei
2001-01-01
The present invention provides a process for the encapsulation of biologically important proteins into transparent, porous silica matrices by an alcohol-free, aqueous, colloidal sol-gel process, and to the biological materials encapsulated thereby. The process is exemplified by studies involving encapsulated cytochrome c, catalase, myoglobin, and hemoglobin, although non-proteinaceous biomaterials, such as active DNA or RNA fragments, cells or even tissues, may also be encapsulated in accordance with the present methods. Conformation, and hence activity of the biomaterial, is successfully retained after encapsulation as demonstrated by optical characterization of the molecules, even after long-term storage. The retained conformation of the biomaterial is strongly correlated to both the rate of gelation and the subsequent drying speed of the encapsulatng matrix. Moreover, in accordance with this process, gelation is accelerated by the use of a higher colloidal solid concentration and a lower synthesis pH than conventional methods, thereby enhancing structural stability and retained conformation of the biomaterials. Thus, the invention also provides a remarkable improvement in retaining the biological activity of the encapsulated biomaterial, as compared with those involved in conventional alkoxide-based processes. It further provides new methods for the quantitative and qualitative detection of test substances that are reactive to, or catalyzed by, the active, encapsulated biological materials.
NASA Astrophysics Data System (ADS)
Sakr, Mahmoud A. S.; Abdel Gawad, El-Sayed A.; Abou Kana, Maram T. H.; Ebeid, El-Zeiny M.
2015-08-01
The photophysical properties such as singlet absorption, molar absorptivity, fluorescence spectra, dipole moment, fluorescence quantum yields, fluorescence lifetimes and laser activity of 1,4-bis (β-Pyridyl-2-Vinyl) Benzene (P2VB), 2,5-distyryl-pyrazine (DSP) and 1,4-bis(2-methylstyryl)benzene(MSB) diolefineic laser dyes have been measured in different restricted hosts. (P2VB), (DSP) and (MSB) are embedded in transparent sol-gel glass and a copolymer of methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA) media. The absorption and fluorescence properties of these laser dyes in sol-gel glass matrices are compared with their respective properties in copolymer host. The photostability of these laser dyes in sol-gel glass and (MMA/HEMA) copolymer samples are measured in terms of half-life method (using nitrogen laser 337.1 nm in pumping), as the number of pulses necessary to reduce the dye laser intensity to 50% of its original value. The gel laser materials show improved photostability upon pumping by nitrogen laser compared with those in organic polymeric host matrix.
NASA Astrophysics Data System (ADS)
Maraeva, E. V.; Bobkov, A. A.; Maximov, A. I.; Moshnikov, V. A.; Nalimova, S. S.
2015-11-01
In this study silicon dioxide - stannic oxide and silicon dioxide - zinc nanomaterials oxide were obtained through sol-gel technology. The results of nitrogen thermal desorption measurements, atomic force microscopy measurements and particle sizes measurements are discussed.
Marwani, Hadi M.; Alsafrani, Amjad E.; Asiri, Abdullah M.; Rahman, Mohammed M.
2016-01-01
A new ionic liquid loaded silica gel amine (SG-APTMS-N,N-EPANTf2) was developed, as an adsorptive material, for selective adsorption and determination of zirconium, Zr(IV), without the need for a chelating intermediate. Based on a selectivity study, the SG-APTMS-N,N-EPANTf2 phase showed a perfect selectivity towards Zr(IV) at pH 4 as compared to other metallic ions, including gold [Au(III)], copper [Cu(II)], cobalt [Co(II)], chromium [Cr(III)], lead [Pb(II)], selenium [Se(IV)] and mercury [Hg(II)] ions. The influence of pH, Zr(IV) concentration, contact time and interfering ions on SG-APTMS-N,N-EPANTf2 uptake for Zr(IV) was evaluated. The presence of incorporated donor atoms in newly synthesized SG-APTMS-N,N-EPANTf2 phase played a significant role in enhancing its uptake capacity of Zr(IV) by 78.64% in contrast to silica gel (activated). The equilibrium and kinetic information of Zr(IV) adsorption onto SG-APTMS-N,N-EPANTf2 were best expressed by Langmuir and pseudo second-order kinetic models, respectively. General co-existing cations did not interfere with the extraction and detection of Zr(IV). Finally, the analytical efficiency of the newly developed method was also confirmed by implementing it for the determination of Zr(IV) in several water samples. PMID:27367692
David, Frank; Devos, Christophe; Dumont, Emmie; Yang, Zhen; Sandra, Pat; Huertas-Pérez, José Fernando
2017-04-01
Two low-pressure columns (Bio-Beads SX-3) and three high-pressure GPC columns were compared for clean-up of a wide range of pesticides in fatty matrices of vegetable or animal origin. The GPC fractions were analyzed by GC-MS/MS and LC-MS/MS without additional clean-up. The performance of the GPC clean-up on the five column types was compared in terms of solvent consumption, lipid removal, pesticide recovery and repeatability. It was found that for fatty matrices, mainly consisting of high molecular weight triglycerides i.e. most vegetable oils and animal fats, good fractionation is obtained for the majority of the pesticides. On the other hand, for fats and oils containing relatively high amounts of low molecular weight triglycerides, i.e. butter fat and palm kernel oil, none of the columns provided sufficient clean-up and cause interferences and system contamination, especially in the case of GC-MS/MS analysis. For the latter case, best results in terms of lipid removal and pesticide recovery were obtained on a set (2×300mmlength) of narrow bore (7.5mm ID) columns packed with 5µm PL Gel material. Column loadability is, however, much lower on that set of columns compared the other evaluated GPC columns, impairing overall method sensitivity.
Spectroscopy in Sol-Gel Matrices: An Open-Ended Laboratory Experience for Upper-Level Undergraduates
NASA Astrophysics Data System (ADS)
Higginbotham, Catrena; Pike, Charles F.; Rice, Jeanette K.
1998-04-01
Guided-inquiry/cooperative learning laboratory experiences encourage critical thinking, problem- solving and teamwork skills in students, and have been proposed for many undergraduate laboratories, particularly general and organic. Fewer reports have appeared for upper level courses such as instrumental analysis. In this report, we discuss our recent conversion of our Instrumental Analysis:Spectroscopy course to guided-inquiry format, and describe an appropriate novel experiment. Sol-gel technology is incorporated as a means to investigate spectral properties of various organic molecules. Students are exposed to silicate glass synthesis as well as modern spectroscopic techniques. Experimental details are researched, designed and executed by the students, and the results presented in both written format as well as oral presentation/examination.
Bhavsar, Bhavik; Choksi, Bimal; Dogra, Alka; Haq, Rizwan; Mehta, Sudhanshu; Mukherjee, Santanu; Subramanian, V; Sheikh, Shafiq; Mittal, Ravindra
2014-01-01
Background: Acne vulgaris of the face is a common dermatological disease with a significant impact on the quality of life, psychosocial development as well as self-esteem of the patients. Nano emulsion gel formulations are said to have various advantages over the conventional formulations. Aim: The present study was conducted to assess the comparative efficacy and safety of a nano-emulsion gel formulation of clindamycin with its conventional formulation in the treatment of acne vulgaris of the face. Materials and Methods: This prospective, active controlled, multicentric, phase IV clinical trial evaluated the treatment of patients with acne vulgaris of the face by a nano emulsion gel formulation or conventional gel formulation of clindamycin (as phosphate) 1% locally applied twice daily for 12 weeks as per random allocation. Acne lesion counts (inflammatory, non-inflammatory and total) and severity grading were carried out on the monthly scheduled visits along with tolerability assessments. Results: A total of 200 patients (97 males) were included for Intention to Treat analysis in the trial with 100 patients in each group. Reductions in total (69.3 vs. 51.9%; p<0.001), inflammatory (73.4 vs. 60.6%; p<0.005) and non inflammatory (65.1 vs. 43.7%; p<0.001) acne lesions were reported to be significantly greater with the nano-emulsion gel formulation as compared to the conventional gel formulation. Significantly more reduction in the mean acne severity score was noticeable with the nano-emulsion gel formulation (-1.6 ± 0.9 vs. -1.0 ± 0.8; p<0.001) than the comparator. A trend towards better safety profile of the nano emulsion gel formulation was reported. Conclusion: In the treatment of acne vulgaris of the face, clindamycin nano emulsion gel formulation appears to be more effective than the conventional gel formulation and is also well tolerated. PMID:25302253
Analyse de la dynamique temporelle d'une molécule unique en matrice sol-gel
NASA Astrophysics Data System (ADS)
Débarre, A.; Tchénio, P.; Azoulay, J.; Jaf Iol, R.; Nutarelli, D.
2002-06-01
L'un des enjeux des études de molécules uniques est de développer des sondes très locales d'un environnement donné. De telles informations ne sont pas accessibles dans les expériences classiques où de nombreuses molécules sont détectées simultanément. Celles-ci ne permettent de déterminer que la valeur moyenne de la distribution d'un paramètre. Parmi les paramètres temporels, la durée de vie des états excités atteints par la molécule occupe une place particulière. Ce paramètre, qui est lié aux propriétés quantiques de la molécule peut varier considérablement si des transferts d'énergie s'établissent entre la molécule et son environnement immédiat. Un autre exemple est la mesure du nombre total de photons émis par la molécule avant qu'elle n'émette plus ( photoblanchiment ). L'arrêt définitif de l'émission est très directement lié aux interactions lumineuses ou collisionnelles que la molécule subit dans les états excités où elle est portée. Cet article décrit d'une part le dispositif expérimental qui a été développé pour déterminer plusieurs paramètres temporels sur la même molécule, et d'autre part les premiers résultats acquis dans des matériaux sol-gels dopés par des molécules dérivées du pérylène[1].
NASA Astrophysics Data System (ADS)
Shurtleff, Richard
2004-10-01
Translation matrices together with rotation and boost matrices combine to represent spacetime symmetry transformations. A brief introduction to some of the properties of some not-so-well-known translation and momentum matrices is presented.
Chandrashekhar, B S; Anitha, M.; Ruparelia, Mukesh; Vaidya, Pradyumna; Aamir, Riyaz; Shah, Sunil; Thilak, S; Aurangabadkar, Sanjeev; Pal, Sandeep; Saraswat, Abir
2015-01-01
Background: Conventional topical tretinoin formulation is often associated with local adverse events. Nanogel formulation of tretinoin has good physical stability and enables good penetration of tretinoin into the pilo-sebaceous glands. Aim: The present study was conducted to assess the efficacy and safety of a nanogel formulation of tretinoin as compared to its conventional gel formulation in the treatment of acne vulgaris of the face. Materials and Methods: This randomized, active controlled, multicentric, phase IV clinical trial evaluated the treatment of patients with acne vulgaris of the face by the two gel formulations locally applied once daily at night for 12 wk. Acne lesion counts (inflammatory, non-inflammatory & total) and severity grading were carried out on the monthly scheduled visits along with the tolerability assessments. Results: A total of 207 patients were randomized in the study. Reductions in the total (72.9% vs. 65.0%; p = 0.03) and inflammatory (78.1% vs. 66.9%; p = 0.02) acne lesions were reported to be significantly greater with the nanogel formulation as compared to the conventional gel formulation. Local adverse events were significantly less (p = 0.04) in the nanogel group (13.3%) as compared to the conventional gel group (24.7%). Dryness was the most common adverse event reported in both the treatment groups while peeling of skin, burning sensation and photosensitivity were reported in patients using the conventional gel only. Conclusion: In the treatment of acne vulgaris of the face, tretinoin nanogel formulation appears to be more effective and better tolerated than the conventional gel formulation. PMID:25738069
Vasquez, B; Reeves, H C
1979-05-23
Affinity chromatography on Affi-Gel Blue has been used to purify the NADP-specific isocitrate dehydrogenase (EC 1.1.1.42) from Escherichia coli. The protocol permits rapid purification of the enzyme in milligram quantities with a yield of 50% and is carried out almost entirely at room temperature. The preparation was judged to be homogeneous by non-denaturing electrophoresis at pH 7.5 and denaturing electrophoresis in the presence of sodium dodecyl sulfate. The subunit molecular weight of 53 000, determined by sodium dodecyl sulfate gel electrophoresis, is in reasonable agreement with the value of 46 900 estimated from the amino acid composition data.
1980-09-29
FOUNDATIONS OF EIGENVALUE DISTRIBUTION THEORY FOR GENERAL A NON--ETC(U) SEP 80 M MARCUS, M GOLDBERG, M NEWMAN AFOSR-79-0127 UNCLASSIFIED AFOSR-TR-80...September 1980 Title of Research: Foundations of Eigenvalue Distribution Theory for General & Nonnegative Matrices, Stability Criteria for Hyperbolic
NASA Astrophysics Data System (ADS)
Zheng, Chan; Zheng, Yingyuan; Chen, Wenzhe; Wei, Li
2015-05-01
Optically transparent organically modified silica (ORMOSIL) gel glasses doped with graphene oxide (GO)/metal nanoparticle (NP) hybrids were synthesized using a simple sol-gel technique. The two-dimensional GO/metal NP hybrids dramatically changed the surface characteristics of silica-based gel glasses whilst maintaining their structural integrity during the sol-gel procedure. The optical limiting (OL) properties of GO/metal NP-doped ORMOSIL gel glasses were investigated using a nanosecond open-aperture Z-scan technique at 532 nm. The metal NP hybrids exhibited significantly enhanced OL performance compared with their individual counterparts in ORMOSIL gel glasses. The improvement in GO/Au NP-doped gel glasses is attributed to surface plasmon resonance, while interband transition is responsible for the enhancement in GO/Pd NP-doped gel glasses. The OL behavior of GO/metal NP-doped gel glasses were mostly attributed to the combined mechanisms of excited state absorption and nonlinear scattering.
Volford, O; Takács, M; Vámos, J
1996-05-01
The properties of silica gel as stationary phase are determined mainly by siloxane, silanol and metal-silanate functional groups. The metals (Na, Ca etc.) getting into the product as trace elements in the course of manufacture may cause the appearance of artefacts. In our previous studies the ion exchange interactions between salt-type analytes and silanol or metal-silanate groups were investigated. It was found in the TLC test of the salts of organic acids and N-bases that the acids and bases are separated from their counter ions and accept protons from or donate to the silica gel layer. In the present paper several analytes of above type have been investigated in situ by remission spectroscopy. These are: phenobarbital, sulfinpyrazone, sulfucetamide, benzoic acid, salicylic acid, (and their Na-salts) and papaverine hydrochloride. Remission spectra were registered from the start spot directly after application and then from the spot after development with the CHCl3EtOH (9 + 1) mobile phase. Based on the difference between the remission spectra of protonated and deprotonated forms of the analytes, the deviations from the initial state could be established. On the basis of the shift of lambda max values one can conclude to the approximate ratio of the protonated (acid) and deprotonated (anion, base) form present in the examined points (middle or edge) of the chromatographic spot. Significantly different protonation states of the analytes were found in the start spots and in the developed spots. These findings are interpreted by the ion exchange interactions between the pharmacon and silica gel. The results provide a deeper insight into the mechanisms of TLC process.
NASA Astrophysics Data System (ADS)
Lewkowicz, Aneta; Synak, Anna; Grobelna, Beata; Bojarski, Piotr; Bogdanowicz, Robert; Karczewski, Jakub; Szczodrowski, Karol; Behrendt, Mirosław
2014-08-01
Titanium dioxide is a well-known material in nanotechnology, while it provides new opportunities due to its interesting properties, for example, as a semiconductor with a quite significant forbidden band gap energy of 3.2 eV. In this study, thin films of titanium dioxide (TiO2) were synthesized in amorphous and crystallographic systems using the sol-gel process. Atomic Force Microscopy (AFM), Raman spectroscopy and X-ray diffraction (XRD) techniques were applied to obtain structural characteristics of the prepared films. We estimated that TiO2 thin films crystallize in anatase phase between temperatures 380 °C and 700 °C, and into anatase-rutile phase at 650 °C, while rutile phase exists alone above 800 °C. The changes in porosity of materials in relation to temperature were calculated as well. The refractive index of titanium dioxide thin films from ellipsometric measurements is also provided.
Zaporozhets, Olga A; Tsyukalo, Lyudmila Ye
2007-07-30
Solid-phase spectrophotometric and visual test-methods of fluoride and oxalate determination are proposed. The methods are based on the competitive reactions of ZrOCl2 with methylthymol blue immobilized on silica gel and fluoride or oxalate in solution. Absorbance of the solid-phase reagent at 590 nm decreases with the growth of fluoride and oxalate contents in solution. The developed methods demonstrate high selectivity. The interference of Bi(III) and SO4(2-), PO4(3-) is eliminated by the addition of 0.01 mol L(-1) solution of ascorbic acid and 0.01 mol L(-1) of BaCl2, respectively. To eliminate the fluoride interference with oxalate determination 1x10(-3) mol L(-1) solution of Ca(NO3)2 at pH 1.5 was added. The anions of the organic acids were destructed prior to F- determination by ultrasonic exposition (44 kHz, intensity of < or = 10 W cm(-2) for 3 min). The proposed methods were applied to the analysis of mineral water, toothpaste and biological fluids.
Miskam, Mazidatulakmam; Abu Bakar, Nor Kartini; Mohamad, Sharifah
2014-03-01
A solid phase extraction (SPE) method has been developed using a newly synthesized titanium (IV) butoxide-cyanopropyltriethoxysilane (Ti-CNPrTEOS) sorbent for polar selective extraction of aromatic amines in river water sample. The effect of different parameters on the extraction recovery was studied using the SPE method. The applicability of the sorbents for the extraction of polar aromatic amines by the SPE was extensively studied and evaluated as a function of pH, conditioning solvent, sample loading volume, elution solvent and elution solvent volume. The optimum experimental conditions were sample at pH 7, dichloromethane as conditioning solvent, 10 mL sample loading volume and 5 mL of acetonitrile as the eluting solvent. Under the optimum conditions, the limit of detection (LOD) and limit of quantification (LOQ) for solid phase extraction using Ti-CNPrTEOS SPE sorbent (0.01-0.2; 0.03-0.61 µg L(-1)) were lower compared with those achieved using Si-CN SPE sorbent (0.25-1.50; 1.96-3.59 µg L(-1)) and C18 SPE sorbent (0.37-0.98; 1.87-2.87 µg L(-1)) with higher selectivity towards the extraction of polar aromatic amines. The optimized procedure was successfully applied for the solid phase extraction method of selected aromatic amines in river water, waste water and tap water samples prior to the gas chromatography-flame ionization detector separation.
ERIC Educational Resources Information Center
Wallace, Edward C.
1985-01-01
Explains an application of matrix algebra which involves probability matrices and weather predictions. Using probabilities of sunny or cloudy weather students can determine the effect weather on day one will have on subsequent days. (DH)
Decomposition of Balanced Matrices. Part 4. Connected Squares
1991-10-01
AD-A247 308 Management Science Research Report #MSRR-572 Decomposition of Balanced Matrices . Part IV: Connected Squares Michele Conforti 2 Gerard...is unlimited. This work was supported in part by NSF grants DDM-8800281, DDM-8901495 and DDM-9001705. tDipartlmento di Matematica Pura ed Applicata...BALANCED MATRICES .• Technical Report, Oct 1991 PART IV: CONNECTED SQUARES 6. PERFORMING ORG. REPORT NUMBER 7. AUTHORS) CONTRACT OR GRANT NUMBER(S) Michele
Srivastava, Bhavya; Barman, Milan K; Chatterjee, Mousumi; Roy, Dipika; Mandal, Bhabatosh
2016-06-17
The present work reports the systematic studies on extraction, separation and preconcentration of Th(IV), U(VI), Zr(IV), Ce(IV) and Cr(III) amid several other foreign ions using EBT anchored {SiO2}n3-D microarray. The effect of various sorption parameters, such as pH, concentration, temperature, sample volume, flow-rate and co-existing foreign ions were investigated. Quantitative sorption was ensured at solution pH: 6.0-6.5 for Th(IV), Ce(IV), Cr(III) and pH: 2.75-3.0 for Zr(IV), U(VI) couple. Analysis on extracted species and extraction sites reveals that [Th4(μ(2)-OH)8(H2O)4](8+), [Ce6(μ(2)-OH)12(H2O)5](12+), [Cr3(μ(2)-OH)4(H2O)](5+), [(UO2)3(μ(2)-OH)5(H2O)3](+) and [Zr4(μ(2)-OH)8(H2O)0.5](8+) for the respective metal ions gets extracted at HOMO of the extractor. HOMO-{metal ion species} was found to be 1:1 complexation. Sorption was endothermic, entropy-gaining, instantaneous and spontaneous in nature. A density functional theory (DFT) calculation has been performed to analyze the 3-D structure and electronic distribution of the synthesized extractor.
Spectral Theory of Matrices. I. General Matrices.
1980-05-01
criterion for similarity of two matrices 93 1.23 The equation AX - XB = C 98 1.24 A case of two nilpotent matrices 101 1.25 Components of a matrix and...following result is needed later. Theorem 1.24.1. Let A C M n(F) be a nilpotent matrix . Put XX . {xlx C in, A kx = 0), k - 0,1 ...... Assume that o - x 0 x x...establishes the theorem in case that A(x) is a nilpotent matrix . Next consider the case where A(x) is an upper triangular matrix whose diagonal entries
A stirred bath technique for diffusivity measurements in cell matrices.
Chresand, T J; Dale, B E; Hanson, S L; Gillies, R J
1988-10-05
A stirred bath technique was developed for determining effective diffusivities in cell matrices. The technique involves cell immobilization in a dilute gel which has negligible effect on solute diffusion. Agar and collagen were tested as immobilizing gels. Agar gel was shown to have minor interactions with the diffusion of various biological molecules, and was used for immobilization of Ehrlich Ascites Tumor (EAT) cells. Diffusivities of glucose and lactic acid were measured in EAT matrices for cell loadings between 20 and 45 vol %. Treatment with glutaraldehyde was effective in quenching the metabolic activity of the cells while preserving their physical properties and diffusive resistance. The measured data agree favorably with predictions based on Maxwell's equation for effective diffusion in a periodic composite material. The stirred bath technique is useful for diffusivity determinations in immobilized matrices or free slurries, and is applicable to both microbial and mammalian cell systems.
Kapetanakou, Anastasia E; Ampavi, Anna; Yanniotis, Stavrianos; Drosinos, Eleftherios H; Skandamis, Panagiotis N
2011-06-01
The present study aimed: (i) to develop models for the combined effect of water activity (0.99, 0.94 and 0.90), microstructure expressed as 0, 5, 10 and 20% w/v gelatin, and temperature (15, 20 and 25 °C), on growth and OTA production rates by Aspergillus carbonarius; and (ii) to evaluate the performance of the developed models on food matrices (jelly, custard and marmalade) of different viscosity at pH 5.5. The square root of biomass increase rate (fungal growth rate) and OTA production rate were determined by the Baranyi model and were further modeled as a function of temperature, gelatin concentration and a(w) by applying polynomial models. Time for visible growth and the upper asymptote of the OTA production curve were also determined by the Baranyi model. Increase in gelatin concentration resulted in a significant delay in all parameters describing fungal growth and OTA production rates, at all temperatures and a(w). The effect of microstructure on fungal growth and OTA production rates was less evident at stress conditions of a(w) and temperature. Detection time for visible fungal growth was markedly influenced by a(w) and temperature. Coefficients of determination were 0.899 and 0.887 for the models predicting the square root (√μ(max)) of growth and OTA production rate, respectively. Predictions of growth rate agreed well with the recorded data of custard and marmalade, while observations of OTA production rate indicated low agreement with model predictions, in all food matrices except for marmalade. The present findings may provide a basis for reliable assessment of the risk of fungal growth and OTA production in foods of different structural and rheological properties.
McGuire, G; Falk, K G
1922-03-20
The conditions for the formation of gels from banana extracts were studied. Gels were obtained with extracts more alkaline than pH 7.0 with very small quantities of calcium, strontium, and barium salts, the gel formation with these salts decreasing in the indicated order. In solutions more acid than pH 6.0, no gels were obtained with these salts. Magnesium, lithium, and sodium salts did not cause gel formation either in acid or alkaline solutions. Pancreatine gave a gel on incubation with banana extract at pH 5.0. The gel-forming property of banana extracts was destroyed on boiling.
STRUMPACK -- STRUctured Matrices PACKage
2014-12-01
STRUMPACK - STRUctured Matrices PACKage - is a package for computations with sparse and dense structured matrix, i.e., matrices that exhibit some kind of low-rank property, in particular Hierarchically Semi Separable structure (HSS). Such matrices appear in many applications, e.g., FEM, BEM, Integral equations. etc. Exploiting this structure using certain compression algorithms allow for fast solution of linear systems and/or fast computation of matrix-vector products, which are the two main building blocks of matrix computations. STRUMPACK has presently two main components: a distributed-memory dense matrix computations package and a shared-memory sparse direct solver.
Fu, Xiaoling; Xu, Meng; Liu, Jie; Qi, Yanmei; Li, Shaohua; Wang, Hongjun
2014-02-01
Nanofibrous matrices hold great promise in skin wound repair partially due to their capability of recapturing the essential attributes of native extracellular matrix (ECM). With regard to limited studies on the effect of nanofibrous matrices on keratinocytes, the present study was aimed to understand how the topographical feature of nanofibrous matrices regulates keratinocyte motility by culturing keratinocytes on polycaprolactone (PCL)/collagen nanofibrous matrices (rough surface with fiber diameters of 331 ± 112 nm) or the matrices coated with a thin layer of collagen gel to form a secondary ultrafine fibrous network (smooth surface with ultrafine fiber diameters of 55 ± 26 nm). It was found that the PCL/collagen nanofibrous matrices alone did not stimulate cell migration, while collagen gel coating could significantly increase cell motility. Further studies demonstrated that the ultrafine fibrous network of collagen gel coating significantly activated integrin β1, Rac1 and Cdc42, facilitated the deposition of laminin-332 (formerly called laminin-5), and promoted the expression of active matrix metalloproteinases (MMPs) (i.e., MMP-2 and 9). Neutralization of integrin β1 activity abrogated the gel coating-induced keratinocyte migration. These findings provide important evidence on the role of topographical features of nanofibrous matrices in regulating the phenotypic alteration of keratinocytes and suggest the possible utility of collagen-containing nanofibrous matrices for skin regeneration especially in re-epithelialization.
Nardova, A.K.; Filippov, E.A.; Glagolenko, Y.B.
1996-05-01
This report presents the results of investigations of plutonium immobilization from solutions on inorganic matrices with the purpose of producing a solid waste form. High-temperature sorption is described which entails the adsorption of radionuclides from solutions on porous, inorganic matrices, as for example silica gel. The solution is brought to a boil with additional thermal process (calcination) of the saturated granules.
Depolarizing differential Mueller matrices.
Ortega-Quijano, Noé; Arce-Diego, José Luis
2011-07-01
The evolution of a polarized beam can be described by the differential formulation of Mueller calculus. The nondepolarizing differential Mueller matrices are well known. However, they only account for 7 out of the 16 independent parameters that are necessary to model a general anisotropic depolarizing medium. In this work we present the nine differential Mueller matrices for general depolarizing media, highlighting the physical implications of each of them. Group theory is applied to establish the relationship between the differential matrix and the set of transformation generators in the Minkowski space, of which Lorentz generators constitute a particular subgroup.
Electrophoresis of DNA in agarose gels, polyacrylamide gels and in free solution.
Stellwagen, Nancy C
2009-06-01
This review describes the electrophoresis of curved and normal DNA molecules in agarose gels, polyacrylamide gels and in free solution. These studies were undertaken to clarify why curved DNA molecules migrate anomalously slowly in polyacrylamide gels but not in agarose gels. Two milestone papers are cited, in which Ferguson plots were used to estimate the effective pore size of agarose and polyacrylamide gels. Subsequent studies on the effect of the electric field on agarose and polyacrylamide gel matrices, DNA interactions with the two gel matrices, and the effect of curvature on the free solution mobility of DNA are also described. The combined results suggest that the anomalously slow mobilities observed for curved DNA molecules in polyacrylamide gels are primarily due to preferential interactions of curved DNAs with the polyacrylamide gel matrix; the restrictive pore size of the matrix is of lesser importance. In free solution, DNA mobilities increase with increasing molecular mass until leveling off at a plateau value of (3.17 +/- 0.01) x 10(-4) cm2/V s in 40 mM Tris-acetate-EDTA buffer at 20 degrees C. Curved DNA molecules migrate anomalously slowly in free solution as well as in polyacrylamide gels, explaining why the Ferguson plots of curved and normal DNAs containing the same number of base pairs extrapolate to different mobilities at zero gel concentration.
ERIC Educational Resources Information Center
Allegheny County Community Coll., Pittsburgh, PA.
Instructional objectives and performance requirements are outlined in this course guide for Welding IV, a competency-based course in advanced arc welding offered at the Community College of Allegheny County to provide students with proficiency in: (1) single vee groove welding using code specifications established by the American Welding Society…
NASA Technical Reports Server (NTRS)
2004-01-01
International VLBI Service (IVS) is an international collaboration of organizations which operate or support Very Long Baseline Interferometry (VLBI) components. The goals are: To provide a service to support geodetic, geophysical and astrometric research and operational activities. To promote research and development activities in all aspects of the geodetic and astrometric VLBI technique. To interact with the community of users of VLBI products and to integrate VLBI into a global Earth observing system.
Drug delivery matrices based on scleroglucan/alginate/borax gels.
Matricardi, Pietro; Onorati, Ilenia; Coviello, Tommasina; Alhaique, Franco
2006-06-19
The aim of this work is to obtain a new drug delivery matrix, especially designed for protein delivery, based on biodegradable and biocompatible polymers, and to describe its main physico-chemical properties. A polysaccharide based semi-interpenetrating polymer network (semi-IPN) was built up, composed by sodium alginate chains interspersed into a scleroglucan/borax hydrogel network. Tablets were obtained by compression of the resulting freeze-dried hydrogel. The different release and physico-chemical properties possessed by the two starting polymers in various aqueous media were combined in the new matrix. In this work, description is given of the in vitro ability of the matrix to deliver in a controlled manner a protein, Myoglobin, in distilled water, simulated gastric fluid and simulated intestinal fluid; the release, simulating a gastric passage, followed by an enteric delivery, was also carried out. Water uptake data, colorimetric experiments and scanning electron microscopy images are given for the characterization of this new solid dosage form; the importance of the borax presence is also discussed.
Enhancing Understanding of Transformation Matrices
ERIC Educational Resources Information Center
Dick, Jonathan; Childrey, Maria
2012-01-01
With the Common Core State Standards' emphasis on transformations, teachers need a variety of approaches to increase student understanding. Teaching matrix transformations by focusing on row vectors gives students tools to create matrices to perform transformations. This empowerment opens many doors: Students are able to create the matrices for…
Intrinsic character of Stokes matrices
NASA Astrophysics Data System (ADS)
Gagnon, Jean-François; Rousseau, Christiane
2017-02-01
Two germs of linear analytic differential systems x k + 1Y‧ = A (x) Y with a non-resonant irregular singularity are analytically equivalent if and only if they have the same eigenvalues and equivalent collections of Stokes matrices. The Stokes matrices are the transition matrices between sectors on which the system is analytically equivalent to its formal normal form. Each sector contains exactly one separating ray for each pair of eigenvalues. A rotation in S allows supposing that R+ lies in the intersection of two sectors. Reordering of the coordinates of Y allows ordering the real parts of the eigenvalues, thus yielding triangular Stokes matrices. However, the choice of the rotation in x is not canonical. In this paper we establish how the collection of Stokes matrices depends on this rotation, and hence on a chosen order of the projection of the eigenvalues on a line through the origin.
Carbon nanomaterials in silica aerogel matrices
Hamilton, Christopher E; Chavez, Manuel E; Duque, Juan G; Gupta, Gautam; Doorn, Stephen K; Dattelbaum, Andrew M; Obrey, Kimberly A D
2010-01-01
Silica aerogels are ultra low-density, high surface area materials that are extremely good thermal insulators and have numerous technical applications. However, their mechanical properties are not ideal, as they are brittle and prone to shattering. Conversely, single-walled carbon nanotubes (SWCNTs) and graphene-based materials, such as graphene oxide, have extremely high tensile strength and possess novel electronic properties. By introducing SWCNTs or graphene-based materials into aerogel matrices, it is possible to produce composites with the desirable properties of both constituents. We have successfully dispersed SWCNTs and graphene-based materials into silica gels. Subsequent supercritical drying results in monolithic low-density composites having improved mechanical properties. These nanocomposite aerogels have great potential for use in a wide range of applications.
Dynamic Electromechanical Hydrogel Matrices for Stem Cell Culture
Lim, Han L.; Chuang, Jessica C.; Tran, Tuan; Aung, Aereas; Arya, Gaurav; Varghese, Shyni
2013-01-01
Hydrogels have numerous biomedical applications including synthetic matrices for cell culture and tissue engineering. Here we report the development of hydrogel based multifunctional matrices that not only provide three-dimensional structural support to the embedded cells but also can simultaneously provide potentially beneficial dynamic mechanical and electrical cues to the cells. A unique aspect of these matrices is that they undergo reversible, anisotropic bending dynamics in an electric field. The direction and magnitude of this bending can be tuned through the hydrogel crosslink density while maintaining the same electric potential gradient, allowing control over the mechanical strain imparted to the cells in a three-dimensional environment. The conceptual design of these hydrogels was motivated through theoretical modeling of the osmotic pressure changes occurring at the gel-solution interfaces in an electric field. These electro-mechanical matrices support survival, proliferation, and differentiation of stem cells. Thus, these new three-dimensional in vitro synthetic matrices, which mimic multiple aspects of the native cellular environment, take us one step closer to in vivo systems. PMID:24273479
Dynamic Electromechanical Hydrogel Matrices for Stem Cell Culture.
Lim, Han L; Chuang, Jessica C; Tran, Tuan; Aung, Aereas; Arya, Gaurav; Varghese, Shyni
2011-01-07
Hydrogels have numerous biomedical applications including synthetic matrices for cell culture and tissue engineering. Here we report the development of hydrogel based multifunctional matrices that not only provide three-dimensional structural support to the embedded cells but also can simultaneously provide potentially beneficial dynamic mechanical and electrical cues to the cells. A unique aspect of these matrices is that they undergo reversible, anisotropic bending dynamics in an electric field. The direction and magnitude of this bending can be tuned through the hydrogel crosslink density while maintaining the same electric potential gradient, allowing control over the mechanical strain imparted to the cells in a three-dimensional environment. The conceptual design of these hydrogels was motivated through theoretical modeling of the osmotic pressure changes occurring at the gel-solution interfaces in an electric field. These electro-mechanical matrices support survival, proliferation, and differentiation of stem cells. Thus, these new three-dimensional in vitro synthetic matrices, which mimic multiple aspects of the native cellular environment, take us one step closer to in vivo systems.
NASA Astrophysics Data System (ADS)
Michel, Patrick; DeMeo, Francesca E.; Bottke, William F.
. Asteroids, like planets, are driven by a great variety of both dynamical and physical mechanisms. In fact, images sent back by space missions show a collection of small worlds whose characteristics seem designed to overthrow our preconceived notions. Given their wide range of sizes and surface compositions, it is clear that many formed in very different places and at different times within the solar nebula. These characteristics make them an exciting challenge for researchers who crave complex problems. The return of samples from these bodies may ultimately be needed to provide us with solutions. In the book Asteroids IV, the editors and authors have taken major strides in the long journey toward a much deeper understanding of our fascinating planetary ancestors. This book reviews major advances in 43 chapters that have been written and reviewed by a team of more than 200 international authorities in asteroids. It is aimed to be as comprehensive as possible while also remaining accessible to students and researchers who are interested in learning about these small but nonetheless important worlds. We hope this volume will serve as a leading reference on the topic of asteroids for the decade to come. We are deeply indebted to the many authors and referees for their tremendous efforts in helping us create Asteroids IV. We also thank the members of the Asteroids IV scientific organizing committee for helping us shape the structure and content of the book. The conference associated with the book, "Asteroids Comets Meteors 2014" held June 30-July 4, 2014, in Helsinki, Finland, did an outstanding job of demonstrating how much progress we have made in the field over the last decade. We are extremely grateful to our host Karri Muinonnen and his team. The editors are also grateful to the Asteroids IV production staff, namely Renée Dotson and her colleagues at the Lunar and Planetary Institute, for their efforts, their invaluable assistance, and their enthusiasm; they made life as
On Some Properties of Gamma Matrices
ERIC Educational Resources Information Center
Dumais, Jean-Francois
1977-01-01
Discusses the problem of the order, reducibility, and equivalence of systems of Dirac gamma matrices. Gives a simple systematic method for finding the matrices connecting different systems of 4 x 4 gamma matrices. (MLH)
Laminin active peptide/agarose matrices as multifunctional biomaterials for tissue engineering.
Yamada, Yuji; Hozumi, Kentaro; Aso, Akihiro; Hotta, Atsushi; Toma, Kazunori; Katagiri, Fumihiko; Kikkawa, Yamato; Nomizu, Motoyoshi
2012-06-01
Cell adhesive peptides derived from extracellular matrix components are potential candidates to afford bio-adhesiveness to cell culture scaffolds for tissue engineering. Previously, we covalently conjugated bioactive laminin peptides to polysaccharides, such as chitosan and alginate, and demonstrated their advantages as biomaterials. Here, we prepared functional polysaccharide matrices by mixing laminin active peptides and agarose gel. Several laminin peptide/agarose matrices showed cell attachment activity. In particular, peptide AG73 (RKRLQVQLSIRT)/agarose matrices promoted strong cell attachment and the cell behavior depended on the stiffness of agarose matrices. Fibroblasts formed spheroid structures on the soft AG73/agarose matrices while the cells formed a monolayer with elongated morphologies on the stiff matrices. On the stiff AG73/agarose matrices, neuronal cells extended neuritic processes and endothelial cells formed capillary-like networks. In addition, salivary gland cells formed acini-like structures on the soft matrices. These results suggest that the peptide/agarose matrices are useful for both two- and three-dimensional cell culture systems as a multifunctional biomaterial for tissue engineering.
Retinal pigment epithelium cell alignment on nanostructured collagen matrices.
Ulbrich, Stefan; Friedrichs, Jens; Valtink, Monika; Murovski, Simo; Franz, Clemens M; Müller, Daniel J; Funk, Richard H W; Engelmann, Katrin
2011-01-01
We investigated attachment and migration of human retinal pigment epithelial cells (primary, SV40-transfected and ARPE-19) on nanoscopically defined, two-dimensional matrices composed of parallel-aligned collagen type I fibrils. These matrices were used non-cross-linked (native) or after riboflavin/UV-A cross-linking to study cell attachment and migration by time-lapse video microscopy. Expression of collagen type I and IV, MMP-2 and of the collagen-binding integrin subunit α(2) were examined by immunofluorescence and Western blotting. SV40-RPE cells quickly attached to the nanostructured collagen matrices and aligned along the collagen fibrils. However, they disrupted both native and cross-linked collagen matrices within 5 h. Primary RPE cells aligned more slowly without destroying either native or cross-linked substrates. Compared to primary RPE cells, ARPE-19 cells showed reduced alignment but partially disrupted the matrices within 20 h after seeding. Expression of the collagen type I-binding integrin subunit α(2) was highest in SV40-RPE cells, lower in primary RPE cells and almost undetectable in ARPE-19 cells. Thus, integrin α(2) expression levels directly correlated with the degree of cell alignment in all examined RPE cell types. Specific integrin subunit α(2)-mediated matrix binding was verified by preincubation with an α(2)-function-blocking antibody, which impaired cell adhesion and alignment to varying degrees in primary and SV40-RPE cells. Since native matrices supported extended and directed primary RPE cell growth, optimizing the matrix production procedure may in the future yield nanostructured collagen matrices serving as transferable cell sheet carriers.
Estimating sparse precision matrices
NASA Astrophysics Data System (ADS)
Padmanabhan, Nikhil; White, Martin; Zhou, Harrison H.; O'Connell, Ross
2016-08-01
We apply a method recently introduced to the statistical literature to directly estimate the precision matrix from an ensemble of samples drawn from a corresponding Gaussian distribution. Motivated by the observation that cosmological precision matrices are often approximately sparse, the method allows one to exploit this sparsity of the precision matrix to more quickly converge to an asymptotic 1/sqrt{N_sim} rate while simultaneously providing an error model for all of the terms. Such an estimate can be used as the starting point for further regularization efforts which can improve upon the 1/sqrt{N_sim} limit above, and incorporating such additional steps is straightforward within this framework. We demonstrate the technique with toy models and with an example motivated by large-scale structure two-point analysis, showing significant improvements in the rate of convergence. For the large-scale structure example, we find errors on the precision matrix which are factors of 5 smaller than for the sample precision matrix for thousands of simulations or, alternatively, convergence to the same error level with more than an order of magnitude fewer simulations.
Numerical inversion of finite Toeplitz matrices and vector Toeplitz matrices
NASA Technical Reports Server (NTRS)
Bareiss, E. H.
1969-01-01
Numerical technique increases the efficiencies of the numerical methods involving Toeplitz matrices by reducing the number of multiplications required by an N-order Toeplitz matrix from N-cubed to N-squared multiplications. Some efficient algorithms are given.
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.
NASA Technical Reports Server (NTRS)
Collins, Earl R., Jr.
1990-01-01
Authorized users respond to changing challenges with changing passwords. Scheme for controlling access to computers defeats eavesdroppers and "hackers". Based on password system of challenge and password or sign, challenge, and countersign correlated with random alphanumeric codes in matrices of two or more dimensions. Codes stored on floppy disk or plug-in card and changed frequently. For even higher security, matrices of four or more dimensions used, just as cubes compounded into hypercubes in concurrent processing.
Nomikou, Nikolitsa; Feichtinger, Georg A; Redl, Heinz; McHale, Anthony P
2016-01-01
It has been suggested that gene transfer into donor cells is an efficient and practical means of locally supplying requisite growth factors for applications in tissue regeneration. Here we describe, for the first time, an ultrasound-mediated system that can non-invasively facilitate gene transfer into cells entrapped within fibrin-based matrices. Since ultrasound-mediated gene transfer is enhanced using microbubbles, we compared the efficacy of neutral and cationic forms of these reagents on the ultrasound-stimulated gene transfer process in gel matrices. In doing so we demonstrated the beneficial effects associated with the use of cationic microbubble preparations that interact directly with cells and nucleic acid within matrices. In some cases, gene expression was increased two-fold in gel matrices when cationic microbubbles were compared with neutral microbubbles. In addition, incorporating collagen into fibrin gels yielded a 25-fold increase in gene expression after application of ultrasound to microbubble-containing matrices. We suggest that this novel system may facilitate non-invasive temporal and spatial control of gene transfer in gel-based matrices for the purposes of tissue regeneration.
Pasting and extrusion properties of mixed carbohydrates and whey protein isolate matrices
Technology Transfer Automated Retrieval System (TEKTRAN)
Mixed systems of whey protein isolate (WPI) or texturized WPI (tWPI) and different starches may form weak or strong gel pastes or rigid matrices depending on interactions. The paste viscoelasticity of starches from amioca, barley, corn starch, Hylon VII, plantain, and pea starch, mixed with whey pro...
Xu, Bin; Li, Haiyue; Zhang, Yanhang
2013-01-01
This study aims to provide understanding of the macroscopic viscoelastic behavior of collagen matrices through studying the relaxation time distribution spectrum obtained from stress relaxation tests. Hydrated collagen gel and dehydrated collagen thin film was exploited as two different hydration levels of collagen matrices. Genipin solution was used to induce crosslinking in collagen matrices. Biaxial stress relaxation tests were performed to characterize the viscoelastic behavior of collagen matrices. The rate of stress relaxation of both hydrated and dehydrated collagen matrices shows a linear initial stress level dependency. Increased crosslinking reduces viscosity in collagen gel, but the effect is negligible for thin film. Relaxation time distribution spectrum was obtained from the stress relaxation data by inverse Laplace transform. For most of the collagen matrices, three peaks at the short (0.3s ~1 s), medium (3s ~90 s), and long relaxation time (> 200 s) were observed in the continuous spectrum, which likely corresponds to relaxation mechanisms involve fiber, inter-fibril, and fibril sliding. Splitting of the middle peak was observed at higher initial stress levels suggesting increased structural heterogeneity at the fibril level with mechanical loading. The intensity of the long-term peaks increases with higher initial stress levels indicating the engagement of collagen fibrils at higher levels of tissue strain.
Iterative methods for Toeplitz-like matrices
Huckle, T.
1994-12-31
In this paper the author will give a survey on iterative methods for solving linear equations with Toeplitz matrices, Block Toeplitz matrices, Toeplitz plus Hankel matrices, and matrices with low displacement rank. He will treat the following subjects: (1) optimal (w)-circulant preconditioners is a generalization of circulant preconditioners; (2) Optimal implementation of circulant-like preconditioners in the complex and real case; (3) preconditioning of near-singular matrices; what kind of preconditioners can be used in this case; (4) circulant preconditioning for more general classes of Toeplitz matrices; what can be said about matrices with coefficients that are not l{sub 1}-sequences; (5) preconditioners for Toeplitz least squares problems, for block Toeplitz matrices, and for Toeplitz plus Hankel matrices.
Yu, Hye-Sun; Lee, Eun-Jung; Seo, Seog-Jin; Knowles, Jonathan C; Kim, Hae-Won
2015-09-01
Exploiting hydrogels for the cultivation of stem cells, aiming to provide them with physico-chemical cues suitable for osteogenesis, is a critical demand for bone engineering. Here, we developed hybrid compositions of collagen and silica into hydrogels via a simple sol-gel process. The physico-chemical and mechanical properties, degradation behavior, and bone-bioactivity were characterized in-depth; furthermore, the in vitro mesenchymal stem cell growth and osteogenic differentiation behaviors within the 3D hybrid gel matrices were communicated for the first time. The hydrolyzed and condensed silica phase enabled chemical links with the collagen fibrils to form networked hybrid gels. The hybrid gels showed improved chemical stability and greater resistance to enzymatic degradation. The in vitro apatite-forming ability was enhanced by the hybrid composition. The viscoelastic mechanical properties of the hybrid gels were significantly improved in terms of the deformation resistance to an applied load and the modulus values under a dynamic oscillation. Mesenchymal stem cells adhered well to the hybrid networks and proliferated actively with substantial cytoskeletal extensions within the gel matrices. Of note, the hybrid gels substantially reduced the cell-mediated gel contraction behaviors, possibly due to the stiffer networks and higher resistance to cell-mediated degradation. Furthermore, the osteogenic differentiation of cells, including the expression of bone-associated genes and protein, was significantly upregulated within the hybrid gel matrices. Together with the physico-chemical and mechanical properties, the cellular behaviors observed within 3D gel matrices, being different from the previous approaches reported on 2D substrates, provide new information on the feasibility and usefulness of the silica-collagen system for stem cell culture and tissue engineering of hard tissues.
Symmetric Toeplitz-Structured Compressed Sensing Matrices
NASA Astrophysics Data System (ADS)
Huang, Tao; Fan, Yi-Zheng; Zhu, Ming
2015-11-01
How to construct a suitable measurement matrix is an important topic in compressed sensing. A significant part of the recent work is that the measurement matrices are not completely random on the entries but exhibit some considerable structures. In this paper, we proved that a symmetric Toeplitz matrix and its variant can be used as measurement matrices and recovery signal with high probability. Compared with random matrices (e.g. Gaussian and Bernoulli matrices) and some structured matrices (e.g. Toeplitz and circulant matrices), we need to generate fewer independent entries to obtain the measurement matrix while the effectiveness of the recovery keeps good.
Open string fields as matrices
NASA Astrophysics Data System (ADS)
Kishimoto, Isao; Masuda, Toru; Takahashi, Tomohiko; Takemoto, Shoko
2015-03-01
We show that the action expanded around Erler-Maccaferri's N D-brane solution describes the N+1 D-brane system where one D-brane disappears due to tachyon condensation. String fields on multi-branes can be regarded as block matrices of a string field on a single D-brane in the same way as matrix theories.
Making almost commuting matrices commute
Hastings, Matthew B
2008-01-01
Suppose two Hermitian matrices A, B almost commute ({parallel}[A,B]{parallel} {<=} {delta}). Are they close to a commuting pair of Hermitian matrices, A', B', with {parallel}A-A'{parallel},{parallel}B-B'{parallel} {<=} {epsilon}? A theorem of H. Lin shows that this is uniformly true, in that for every {epsilon} > 0 there exists a {delta} > 0, independent of the size N of the matrices, for which almost commuting implies being close to a commuting pair. However, this theorem does not specifiy how {delta} depends on {epsilon}. We give uniform bounds relating {delta} and {epsilon}. The proof is constructive, giving an explicit algorithm to construct A' and B'. We provide tighter bounds in the case of block tridiagonal and tridiagnonal matrices. Within the context of quantum measurement, this implies an algorithm to construct a basis in which we can make a projective measurement that approximately measures two approximately commuting operators simultaneously. Finally, we comment briefly on the case of approximately measuring three or more approximately commuting operators using POVMs (positive operator-valued measures) instead of projective measurements.
Fibonacci Identities, Matrices, and Graphs
ERIC Educational Resources Information Center
Huang, Danrun
2005-01-01
General strategies used to help discover, prove, and generalize identities for Fibonacci numbers are described along with some properties about the determinants of square matrices. A matrix proof for identity (2) that has received immense attention from many branches of mathematics, like linear algebra, dynamical systems, graph theory and others…
Intelligent Virtual Station (IVS)
NASA Technical Reports Server (NTRS)
2002-01-01
The Intelligent Virtual Station (IVS) is enabling the integration of design, training, and operations capabilities into an intelligent virtual station for the International Space Station (ISS). A viewgraph of the IVS Remote Server is presented.
Inorganic Nanoparticle Nucleation on Polymer Matrices
NASA Astrophysics Data System (ADS)
Kosteleski, Adrian John
dressing applications. PAA's ability to nucleate nanoparticles in a solid matrix was displayed. Interestingly enough PAA retains its ability to nucleate nanoparticle even when its reactive functional groups are used in the crosslinking process. Silver nanoparticle composition and size on the solid polymer matrices was controlled by varying the composition of PAA. PAA and silver nanoparticles effect on the mechanical properties of the calcium alginate hydrogels were also studied. Physically crosslinking PAA with calcium alginate gels enables the development of intricate gel structures that are decorated with nucleated silver; yielding a composite biomaterial with improved and enhanced antimicrobial properties.
... hyphen, e.g. -historical Searches are case-insensitive Ovarian Cancer Stage IV Add to My Pictures View /Download : ... 1200x1335 View Download Large: 2400x2670 View Download Title: Ovarian Cancer Stage IV Description: Drawing of stage IV shows ...
Laser Performance of Some Oxazole Laser Dyes in Restricted Matrices.
Sakr, Mahmoud A S; Abdel Gawad, Sayed A; Abou Kana, Maram T H; Ebeid, El-Zeiny M
2017-03-13
This article reports the optical properties such as absorption profile, molar absorptivity, fluorescence profile and photo-physical parameters such as dipole moment, oscillator strength, fluorescence quantum yields, fluorescence lifetimes, laser performance and finally photostability of 2,5-Bis(5-tert-butyl-benzoxazol-2-yl)thiophene (BBOT),1,4-Bis(5-phenyl-2-oxazolyl)benzene (POPOB), 5-diphenyel-oxazole (PPO) laser dyes in different restricted hosts. (BBOT), (POPOB) and (PPO) are embedded in transparent silica-based nanoporous sol-gel glass and copolymer matrix of methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA). The absorption and fluorescence properties of these laser dyes in sol-gel glass matrices are compared with their respective properties in copolymer host. In case of sol-gel matrix, all dyes had higher quantum yields as well as lasing wavelength maxima. The laser performances as well as the photostability of these laser dyes in sol-gel glass displayed senior behavior compared with (MMA/ HEMA) copolymer samples upon using nitrogen laser (337.1 nm) as pumping energy.
NASA Astrophysics Data System (ADS)
Bombardelli, Diego
2016-08-01
In these notes we review the S-matrix theory in (1+1)-dimensional integrable models, focusing mainly on the relativistic case. Once the main definitions and physical properties are introduced, we discuss the factorization of scattering processes due to integrability. We then focus on the analytic properties of the two-particle scattering amplitude and illustrate the derivation of the S-matrices for all the possible bound states using the so-called bootstrap principle. General algebraic structures underlying the S-matrix theory and its relation with the form factors axioms are briefly mentioned. Finally, we discuss the S-matrices of sine-Gordon and SU(2), SU(3) chiral Gross-Neveu models. In loving memory of Lilia Grandi.
Temperature Mapping in Hydrogel Matrices Using Unmodified Digital Camera.
Darwish, Ghinwa H; Fakih, Hassan H; Karam, Pierre
2017-02-09
We report a simple, generally applicable, and noninvasive fluorescent method for mapping thermal fluctuations in hydrogel matrices using an unmodified commercially available digital single-lens reflex camera (DSLR). The nanothermometer is based on the complexation of short conjugated polyelectrolytes, poly(phenylene ethynylene) carboxylate, with an amphiphilic polymer, polyvinylpyrrolidone, which is in turn trapped within the porous network of a gel matrix. Changes in the temperature lead to a fluorescent ratiometric response with a maximum relative sensitivity of 2.0% and 1.9% at 45.0 °C for 0.5% agarose and agar, respectively. The response was reversible with no observed hysteresis when samples were cycled between 20 and 40 °C. As a proof of concept, the change in fluorescent signal/color was captured using a digital camera. The images were then dissected into their red-green-blue (RGB) components using a Matlab routine. A linear correlation was observed between the hydrogel temperature and the green and blue intensity channels. The reported sensor has the potential to provide a wealth of information when thermal fluctuations mapped in soft gels matrices are correlated with chemical or physical processes.
Rotationally invariant ensembles of integrable matrices.
Yuzbashyan, Emil A; Shastry, B Sriram; Scaramazza, Jasen A
2016-05-01
We construct ensembles of random integrable matrices with any prescribed number of nontrivial integrals and formulate integrable matrix theory (IMT)-a counterpart of random matrix theory (RMT) for quantum integrable models. A type-M family of integrable matrices consists of exactly N-M independent commuting N×N matrices linear in a real parameter. We first develop a rotationally invariant parametrization of such matrices, previously only constructed in a preferred basis. For example, an arbitrary choice of a vector and two commuting Hermitian matrices defines a type-1 family and vice versa. Higher types similarly involve a random vector and two matrices. The basis-independent formulation allows us to derive the joint probability density for integrable matrices, similar to the construction of Gaussian ensembles in the RMT.
Genetic code, hamming distance and stochastic matrices.
He, Matthew X; Petoukhov, Sergei V; Ricci, Paolo E
2004-09-01
In this paper we use the Gray code representation of the genetic code C=00, U=10, G=11 and A=01 (C pairs with G, A pairs with U) to generate a sequence of genetic code-based matrices. In connection with these code-based matrices, we use the Hamming distance to generate a sequence of numerical matrices. We then further investigate the properties of the numerical matrices and show that they are doubly stochastic and symmetric. We determine the frequency distributions of the Hamming distances, building blocks of the matrices, decomposition and iterations of matrices. We present an explicit decomposition formula for the genetic code-based matrix in terms of permutation matrices, which provides a hypercube representation of the genetic code. It is also observed that there is a Hamiltonian cycle in a genetic code-based hypercube.
Rotationally invariant ensembles of integrable matrices
NASA Astrophysics Data System (ADS)
Yuzbashyan, Emil A.; Shastry, B. Sriram; Scaramazza, Jasen A.
2016-05-01
We construct ensembles of random integrable matrices with any prescribed number of nontrivial integrals and formulate integrable matrix theory (IMT)—a counterpart of random matrix theory (RMT) for quantum integrable models. A type-M family of integrable matrices consists of exactly N -M independent commuting N ×N matrices linear in a real parameter. We first develop a rotationally invariant parametrization of such matrices, previously only constructed in a preferred basis. For example, an arbitrary choice of a vector and two commuting Hermitian matrices defines a type-1 family and vice versa. Higher types similarly involve a random vector and two matrices. The basis-independent formulation allows us to derive the joint probability density for integrable matrices, similar to the construction of Gaussian ensembles in the RMT.
Sol-gel based optical chemical sensors
NASA Astrophysics Data System (ADS)
Lobnik, Aleksandra; Korent Urek, Špela; Turel, Matejka; Frančič, Nina
2011-05-01
The growing activity in the field of optical chemical sensors has resulted in numerous sensing schemes, new indicator dyes, various polymeric matrix, size and shapes and highly diversified methods of immobilization. The sensor characteristics are dependent upon the choice of indicator, polymer, immobilization technique, and also size. Sol-gel technology provides a low-temperature method for obtaining porous silicate glass matrices. It enables to obtain material in the form of films, powders, monoliths, fibres or nanoparticles. Organic reagents and molecular receptors can be easily immobilized in the matrices. Moreover, one of the unique features of the sol-gel process is that the properties of the final network structure, such as hydrophobicity, thickness, porosity, flexibility, reactivity and stability can be easily tailored by controlling the process conditions, the type and the size of the precursors and catalysis. Here we will report about several sensor designed over the years based on sol-gel materials for monitoring and controlling different parameters, such as heavy metals, amines, phosphates, organophosphates.
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.
Musiał-Kulik, Monika; Kasperczyk, Janusz; Jelonek, Katarzyna; Dobrzyński, Piotr; Gebarowska, Katarzyna; Janeczek, Henryk; Libera, Marcin
2010-01-01
Biodegradable polymers have become common materials used in pharmacy and medicine due to their properties such as mechanical strength, biocompatibility and non-toxic degradation products. Different compositions of copolymers and also their chain microstructure may have an effect on matrices degradation and thus on the drug release profile. In our study, we aimed at the influence of paclitaxel content on hydrolytic degradation process of terpolymeric matrices. Hydrolytic degradation of three kinds of matrices (with 5 or 10% of paclitaxel and drug free matrices) prepared from three types of terpolymers was performed in vitro at 37 degrees C in phosphate buffer solution (PBS, pH 7,4). The 1H and 13C NMR spectra of terpolymers were recorded. Thermal properties were monitored by differential scanning calorimetry (DSC). Molecular weight dispersity (D) and molecular weight were determined using gel permeation chromatography (GPC). The surface morphology was studied by means of the scanning electron microscopy (SEM). The most significant degradation was observed in case of poly(L-lactide-co-glycolide-co-epsilon-caprolactone) 44:32:24. Weight loss and water uptake were similar in the event of the same type of matrices obtained from the two poly(L-lactide-co-glycolide-co-TMC). Decelerated paclitaxel release in case of matrices with 51:26:23 molar ratio was noticed and it can be connected with higher content of carbonate units. Knowledge of paclitaxel influence on hydrolytic degradation process may contribute to receive valuable information about its release mechanisms from biodegradable terpolymers.
Canonical form of Hamiltonian matrices
NASA Astrophysics Data System (ADS)
Zuker, A. P.; Waha Ndeuna, L.; Nowacki, F.; Caurier, E.
2001-08-01
On the basis of shell model simulations, it is conjectured that the Lanczos construction at fixed quantum numbers defines-within fluctuations and behavior very near the origin-smooth canonical matrices whose forms depend on the rank of the Hamiltonian, dimensionality of the vector space, and second and third moments. A framework emerges that amounts to a general Anderson model capable of dealing with ground state properties and strength functions. The smooth forms imply binomial level densities. A simplified approach to canonical thermodynamics is proposed.
Energy levels and lifetimes of Nd IV, Pm IV, Sm IV, and Eu IV
Dzuba, V. A.; Safronova, U. I.; Johnson, W. R.
2003-09-01
To address the shortage of experimental data for electron spectra of triply ionized rare-earth elements we have calculated energy levels and lifetimes of 4f{sup n+1} and 4f{sup n}5d configurations of Nd IV (n=2), Pm IV (n=3), Sm IV (n=4), and Eu IV (n=5) using Hartree-Fock and configuration-interaction methods. To control the accuracy of our calculations we also performed similar calculations for Pr III, Nd III, and Sm III, for which experimental data are available. The results are important, in particular, for physics of magnetic garnets.
Zhang, Qilei; Gladden, Lynn; Avalle, Paolo; Mantle, Michael
2011-12-20
Swellable polymeric matrices are key systems in the controlled drug release area. Currently, the vast majority of research is still focused on polymer swelling dynamics. This study represents the first quantitative multi-nuclear (((1))H and ((19))F) fast magnetic resonance imaging study of the complete dissolution process of a commercial (Lescol® XL) tablet, whose formulation is based on the hydroxypropyl methylcellulose (HPMC) polymer under in vitro conditions in a standard USP-IV (United States Pharmacopeia apparatus IV) flow-through cell that is incorporated into high field superconducting magnetic resonance spectrometer. Quantitative RARE ((1))H magnetic resonance imaging (MRI) and ((19))F nuclear magnetic resonance (NMR) spectroscopy and imaging methods have been used to give information on: (i) dissolution media uptake and hydrodynamics; (ii) active pharmaceutical ingredient (API) mobilisation and dissolution; (iii) matrix swelling and dissolution and (iv) media activity within the swelling matrix. In order to better reflect the in vivo conditions, the bio-relevant media Simulated Gastric Fluid (SGF) and Fasted State Simulated Intestinal Fluid (FaSSIF) were used. A newly developed quantitative ultra-fast MRI technique was applied and the results clearly show the transport dynamics of media penetration and hydrodynamics along with the polymer swelling processes. The drug dissolution and mobility inside the gel matrix was characterised, in parallel to the ((1))H measurements, by ((19))F NMR spectroscopy and MRI, and the drug release profile in the bulk solution was recorded offline by UV spectrometer. We found that NMR spectroscopy and 1D-MRI can be uniquely used to monitor the drug dissolution/mobilisation process within the gel layer, and the results from ((19))F NMR spectra indicate that in the gel layer, the physical mobility of the drug changes from "dissolved immobilised drug" to "dissolved mobilised drug".
A polarized photobleaching study of DNA reorientation in agarose gels
Scalettar, B.A.; Klein, M.P. ); Selvin, P.R.; Hearst, J.E. Univ. of California, Berkeley ); Axelrod, D. )
1990-05-22
Polarized fluorescence recovery after photobleaching (pFRAP) has been used to study the internal dynamics of relatively long DNA molecules embedded in gels that range in concentration from 1% to 5% agarose. The data indicate that, even in very congested gels, rapid internal relaxation of DNA is largely unhindered; however, interactions with gel matrices apparently do perturb the larger amplitude, more slowly (microseconds to milliseconds) relaxing internal motions of large DNAs. The relationship between this work and recent studies which indicate that internal motions of DNA play an important role in the separation achieved with pulsed-field gel electrophoresis techniques is discussed. The polarized photobleaching technique is also analyzed in some detail. In particular, it is shown that reversible photobleaching phenomena are probably related to depletion of the ground state by intersystem crossing to the triplet state.
Behaviour of whey protein emulsion gel during oral and gastric digestion: effect of droplet size.
Guo, Qing; Ye, Aiqian; Lad, Mita; Dalgleish, Douglas; Singh, Harjinder
2014-06-21
A set of whey protein stabilized-emulsion gels with different droplet size distributions (D4,3 = ∼1, 6 and 12 μm) was produced, and the mechanical properties of the gels in the linear viscoelastic region and at large deformation were measured, along with the physicochemical and structural changes of the gels during oral mastication and gastric digestion. The gels containing 1 μm oil droplets had an aggregated particle structure with proteins coating at oil droplets whereas the gels containing 12 μm oil droplets had a particle-filled structure with spatially continuous matrix. During oral processing, the release of oil droplets from the gels increased as the droplet size increased, with coalescence being seen in gels containing oil droplets of 6 and 12 μm diameter. Under gastric digestion, high degrees of coalescence and phase separation of oil droplets occurred in the gels containing 6 and 12 μm oil droplets because of oil droplet release from the gel matrix; this led to slow gastric emptying. The gels were finally broken down into peptide aggregates and oil droplets (or free oil). The gels, containing 1 μm oil droplets disintegrated into various particles of several to several tens of microns with a low degree of oil droplet release and coalescence. Protein breakdown was slower in these gels, suggesting that the protein structures of the gel matrices were affected by the sizes of the incorporated oil droplets.
Solvent-induced lysozyme gels: rheology, fractal analysis, and sol-gel kinetics.
da Silva, Marcelo A; Arêas, Elizabeth P G
2005-09-15
In this work, the gelation kinetics and fractal character of lysozyme gel matrices developed in tetramethylurea (TMU)-water media were investigated. Gelation times were determined from the temporal crossover point between the storage, G', and loss, G'', moduli, as a function of the binary solvent composition and of protein concentration. The inverse dependence of the upper limit of the linear viscoelastic region (gamma0) on protein concentration indicate that the lysozyme gels belong to the "strong link" kind, a gel category where interparticle links are stronger than intraparticle ones. Lysozyme gel fractal dimensions (Df) were determined from the analysis of rheological data according to a scaling theory by Shih et al. [Phys. Rev. A 42 (1990) 4772-4779] and were found to be compatible with a diffusion-limited cluster-aggregation kinetics (DLCA) for lysozyme gels formed at the TMU mass fraction in the binary organic-aqueous solvent, wTMU=0.9, and with a reaction-limited cluster aggregation kinetics (RLCA) for wTMU in the 0.6< or =wTMU< or =0.8 range.
Carbon in the matrices of ordinary chondrites
NASA Astrophysics Data System (ADS)
Makjanic, J.; Vis, R. D.; Hovenier, J. W.; Heymann, D.
1993-03-01
Carbon in the petrologic matrices of a number of ordinary chondrites of groups H, L, and LL, and of types 3 through 6 was studied with a nuclear microprobe and a Raman microprobe. The majority of the matrices had carbon contents in the narrow range between 0.03 and 0.2 wt pct. The carbon content decreased only slightly with increasing petrologic type. Carbon-rich coats around troilite and/or metal phases occurred in five meteorites. Poorly ordered carbon was found in the matrices. The carbon in the meteorites of higher petrologic types was slightly better ordered than in the meteorites of lower types. The narrow range of carbon contents and the similarity of the structural form of carbon in the matrices of the measured ordinary chondrites, which represent all groups and types, imply that their matrices may contain a common component, which might be of interstellar origin.
Sol-gel-derived hybrid materials multi-doped with rare-earth metal ions
NASA Astrophysics Data System (ADS)
Zelazowska, E.; Rysiakiewicz-Pasek, E.; Borczuch-Laczka, M.; Cholewa-Kowalska, K.
2012-06-01
Four different hybrid organic-inorganic materials based on TiO2-SiO2 matrices with organic additives and doped with rare-earth metal ions (III) from the group of europium, cerium, terbium, neodymium, dysprosium and samarium, were synthesized by sol-gel method. Tetraethyl orthosilicate, titanium (IV) isopropoxide and organic compounds, such as butyl acrylate, butyl methacrylate, ethyl acetoacetate, ethylene glycol dimethacrylate, ethyl acetate, propylene carbonate, organic solvents and certain inorganic salts were used in the synthesis. The inorganic part of the sols, which were used in the synthesis of all the hybrid materials, was prepared separately and then the organic parts were added. The materials obtained were aged for three weeks at room temperature and then heated in an electric oven for three hours at temperatures of 80 °C-150 °C. Scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM/EDX); X-ray diffraction (XRD); Fourier transform infrared spectroscopy (KBr technique); 29Si magic-angle spinning nuclear magnetic resonance; and fluorescence spectroscopy were used for the examination of morphology, microstructure and luminescence properties, respectively. Photoluminescence properties with relatively intense narrow emission lines of Tb, Eu, Dy, Nd, Sm respectively to the RE-ions doping, were observed for all the hybrid materials.
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.
... venous catheter - home; Port - home; PICC line - home; Infusion therapy - home; Home health care - IV treatment ... is given quickly, all at once. A slow infusion, which means the medicine is given slowly over ...
Apparatus for the production of gel beads containing a biocatalyst
Scott, C.D.; Scott, T.C.; Davison, B.H.
1998-03-19
An apparatus is described for the large-scale and continuous production of gel beads containing a biocatalyst. The apparatus is a columnar system based on the chemical cross-linking of hydrocolloidal gels that contain and immobilize a biocatalyst, the biocatalyst being a microorganism or an enzyme. Hydrocolloidal gels, such as alginate, carrageenan, and a mixture of bone gelatin and modified alginate, provide immobilization matrices that can be used to entrap and retain the biocatalyst while allowing effective contact with substrates and release of products. Such immobilized biocatalysts are generally formulated into small spheres or beads that have high concentrations of the biocatalyst within the gel matrix. The columnar system includes a gel dispersion nozzle submerged in a heated non-interacting liquid, typically an organic liquid, that is immiscible with water to allow efficient formation of spherical gel droplets, the non-interacting liquid having a specific gravity that is less than water so that the gel droplets will fall through the liquid by the force of gravity. The heated non-interacting liquid is in direct contact with a chilled upflowing non-interacting liquid that will provide sufficient residence time for the gel droplets as they fall through the liquid so that they will be cooled below the gelling temperature and form solid spheres. The upflowing non-interacting liquid is in direct contact with an upflowing temperature-controlled aqueous solution containing the necessary chemicals for cross-linking or fixing of the gel beads to add the necessary stability. The flow rates of the two liquid streams can be varied to control the proper residence time in each liquid section to accommodate the production of gel beads of differing settling velocities. A valve is provided for continuous removal of the stabilized gel beads from the bottom of the column. 1 fig.
Apparatus for the production of gel beads containing a biocatalyst
Scott, Charles D.; Scott, Timothy C.; Davison, Brian H.
1998-01-01
An apparatus for the large-scale and continuous production of gel beads containing a biocatalyst. The apparatus is a columnar system based on the chemical cross-linking of hydrocolloidal gels that contain and immobilize a biocatalyst, the biocatalyst being a microorganism or an enzyme. Hydrocolloidal gels, such as alginate, carrageenan, and a mixture of bone gelatin and modified alginate, provide immobilization matrices that can be used to entrap and retain the biocatalyst while allowing effective contact with substrates and release of products. Such immobilized biocatalysts are generally formulated into small spheres or beads that have high concentrations of the biocatalyst within the gel matrix. The columnar system includes a gel dispersion nozzle submerged in a heated non-interacting liquid, typically an organic liquid, that is immiscible with water to allow efficient formation of spherical gel droplets, the non-interacting liquid having a specific gravity that is less than water so that the gel droplets will fall through the liquid by the force of gravity. The heated non-interacting liquid is in direct contact with a chilled upflowing non-interacting liquid that will provide sufficient residence time for the gel droplets as they fall through the liquid so that they will be cooled below the gelling temperature and form solid spheres. The upflowing non-interacting liquid is in direct contact with an upflowing temperature-controlled aqueous solution containing the necessary chemicals for cross-linking or fixing of the gel beads to add the necessary stability. The flow rates of the two liquid streams can be varied to control the proper residence time in each liquid section to accommodate the production of gel beads of differing settling velocities. A valve is provided for continuous removal of the stabilized gel beads from the bottom of the column.
NASA Technical Reports Server (NTRS)
Mortensen, L. O.
1982-01-01
The Mark IV ground communication facility (GCF) as it is implemented to support the network consolidation program is reviewed. Changes in the GCF are made in the area of increased capacity. Common carrier circuits are the medium for data transfer. The message multiplexing in the Mark IV era differs from the Mark III era, in that all multiplexing is done in a GCF computer under GCF software control, which is similar to the multiplexing currently done in the high speed data subsystem.
Sun, Han-Wen; Wang, Feng-Chi; Ai, Lian-Feng
2007-09-14
An accurate method based on the use of gel permeation chromatography (GPC)-liquid chromatography-tandem mass spectrometry interfaced with electrospray ionization (GPC-LC-ESI-MS/MS) was devised for the simultaneous determination of Sudan (I-IV), Sudan Orange G, Sudan Red B, Sudan Red G, Sudan Red 7B, Butter Yellow and Para Red in hot chili products. A GPC clean-up procedure was developed for simultaneous quantification of 10 dyes in hot chili and hot chili products avoiding some interference and permitting multiple injections without damaging the column. A HPLC was performed on an Inertsil C18 column using a multistep gradient elution with 0.1% formic acid and methanol as the mobile phase. Mass spectral acquisition was done in positive ion mode. Linearity of around three orders in the magnitude of concentration was generally obtained with the correlation coefficients (r2) of 0.9984-0.9997. Limit of detection (LOD) and limit of quantification (LOQ) for the investigated dyes were in the ranges of 0.1-1.8 and 0.4-5.0 microg/kg depending on matrices, respectively. The recoveries of the 10 synthetic dyes in five matrices ranged from 81.7 to 92.9%. The intra- and inter-day precision (RSDs) was between 2.9-7.8 and 3.9-8.1%, respectively. This method has been applied successfully for the determination of the studied 10 banned dyes in hot chili products.
Effect of additives on physicochemical properties in amorphous starch matrices.
Liang, Jun; Wang, Simon; Ludescher, Richard D
2015-03-15
The effect of the addition of non-reducing sugars or methylcellulose on the matrix physical properties and rate of non-enzymatic browning (NBR) between exogenous glucose+lysine in a starch-based glassy matrix were studied, using the methods of luminescence and FTIR. Amorphous starch-based matrices were formulated by rapidly dehydrating potato starch gel mixed with additives at weight ratios of 7:93 (additive:starch). Data on the phosphorescence emission energy and lifetime from erythrosin B dispersed in the matrices indicated that sugars decreased starch matrix mobility in a Tg-dependent manner, except for trehalose that interacted with starch in a unique mode, while methylcellulose, the additive with the highest Tg, increased the molecular mobility. Using FTIR, we found that methylcellulose decreased the strength of hydrogen bond network and sugars enhanced the hydrogen bond strength in the order: trehalose>maltitol>sucrose. Comparing those changes with the rate of NBR between exogenous glucose+lysine, we suggest that NBR rates are primarily influenced by matrix mobility, which is modulated by the hydrogen bond network, and interactions among components.
Cracks and Topological Defects in Lyotropic Nematic Gels
NASA Astrophysics Data System (ADS)
Islam, M. F.; Nobili, M.; Ye, Fangfu; Lubensky, T. C.; Yodh, A. G.
2005-09-01
We report on the effects of the coupling of nematic order and elasticity in anisotropic lyotropic gels consisting of large nematic domains of surfactant coated single wall carbon nanotubes embedded in a cross-linked N-isopropyl acrylamide polymer matrix. We observe the following striking features: (i) undulations and then cusping of the gel sidewalls, (ii) a nematic director field that evolves as the gel sidewalls deform, (iii) networks of surface cracks that are orthogonal to the nematic director field, and (iv) fissures at the sidewall cusps and associated topological defects that would not form in liquid nematics.
Characterizing the inverses of block tridiagonal, block Toeplitz matrices
NASA Astrophysics Data System (ADS)
Boffi, Nicholas M.; Hill, Judith C.; Reuter, Matthew G.
2015-01-01
We consider the inversion of block tridiagonal, block Toeplitz matrices and comment on the behaviour of these inverses as one moves away from the diagonal. Using matrix Möbius transformations, we first present an O(1) representation (with respect to the number of block rows and block columns) for the inverse matrix and subsequently use this representation to characterize the inverse matrix. There are four symmetry-distinct cases where the blocks of the inverse matrix (i) decay to zero on both sides of the diagonal, (ii) oscillate on both sides, (iii) decay on one side and oscillate on the other and (iv) decay on one side and grow on the other. This characterization exposes the necessary conditions for the inverse matrix to be numerically banded and may also aid in the design of preconditioners and fast algorithms. Finally, we present numerical examples of these matrix types.
Sethi, Amit; Karl, Zachary J; Scharf, Michael E
2016-04-01
Termites are highly effective digesters of wood lignocellulose, which is a central factor contributing to their global status as pests of wooden structures. For the same reason, termite baits that combine cellulosic matrices with slow-acting insecticides are both effective and popular as a reduced-risk approach for termite control. This study took a novel approach for assessing digestibility of termite bait matrices and matrix components to gain potentially new insights into bait attractiveness and efficacy. The rationale behind this study is that termite baits that are more digestible should have more nutritional value to termites and thus encourage maximal feeding and trophallactic transfer of active ingredients through termite colonies. Studies were done using in vitro digestion assays with termite gut protein extracts followed by colorimetric detection of released glucose and pentose monosaccharides from test substrates. The substrates tested included two commercial bait matrices (Recruit IV and Recruit II HD), two matrix components (compressed and toasted compressed cellulose), and two natural pine woods as positive controls (southern yellow and northern pine). Overall results show equal or greater monosaccharide availability for some commercial matrices than standard pine lignocelluloses, suggesting sufficient nutritional value for the proprietary matrices. Another more prominent trend was significant intercolony variation in digestibility across substrates, possibly resulting from differences in microbiota composition, long-term diet adaptation, or both. These findings thus illuminate new nutrition-based factors that can potentially impact bait feeding, trophallactic exchange, and efficacy.
Optical pH sensor based on sol-gel-doped new luminescent dye
NASA Astrophysics Data System (ADS)
Lobnik, Aleksandra; Niederreiter, Karlheinz; Uray, Georg
1999-11-01
The sol-gel process is an exciting new technology that enables the production of gel glasses and ceramic materials at room temperature. Sol-gel technology offers simple methods for manipulation of the structure, configuration, composition and chemical characteristics of organic matrices. A novel longwave luminescent dye based on the europium luminescence initiated by a covalently bonded antenna fluorophore was designed, synthesized and characterized. The dye was successfully entrapped into various sol-gel and ormosil matrices and consequent optical- , leaching- and light fastness-properties were tested. Finally, sensor layer based on TMOS doped with Eu3+- complex and bromothymol blue was found to be most appropriate for purposes of sensing pH over the range 5-10.
Rotationally invariant ensembles of integrable matrices
NASA Astrophysics Data System (ADS)
Scaramazza, Jasen; Yuzbashyan, Emil; Shastry, Sriram
We construct ensembles of random integrable matrices with any prescribed number of nontrivial integrals and formulate integrable matrix theory (IMT) - a counterpart of random matrix theory (RMT) for quantum integrable models. A type- M family of integrable matrices consists of exactly N - M independent commuting N × N matrices linear in a real parameter. We first develop a rotationally invariant parameterization of such matrices, previously only constructed in a preferred basis. For example, an arbitrary choice of a vector and two commuting Hermitian matrices defines a type-1 family and vice-versa. Higher types similarly involve a random vector and two matrices. The basis-independent formulation allows us to derive the joint probability density for integrable matrices, in a manner similar to the construction of Gaussian ensembles in the RMT. This work was supported in part by the David and Lucille Packard Foundation. The work at UCSC was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES) under Award # FG02-06ER46319.
Pulse Field Gel Electrophoresis
Sharma-Kuinkel, Batu K.; Rude, Thomas H.; Fowler, Vance G.
2015-01-01
Pulse Field Gel Electrophoresis (PFGE) is a powerful genotyping technique used for the separation of large DNA molecules (entire genomic DNA) after digesting it with unique restriction enzymes and applying to a gel matrix under the electric field that periodically changes direction. PFGE is a variation of agarose gel electrophoresis that permits analysis of bacterial DNA fragments over an order of magnitude larger than that with conventional restriction enzyme analysis. It provides a good representation of the entire bacterial chromosome in a single gel with a highly reproducible restriction profile, providing clearly distinct and well-resolved DNA fragments. PMID:25682374
Pulse Field Gel Electrophoresis.
Sharma-Kuinkel, Batu K; Rude, Thomas H; Fowler, Vance G
2016-01-01
Pulse Field Gel Electrophoresis (PFGE) is a powerful genotyping technique used for the separation of large DNA molecules (entire genomic DNA) after digesting it with unique restriction enzymes and applying to a gel matrix under the electric field that periodically changes direction. PFGE is a variation of agarose gel electrophoresis that permits analysis of bacterial DNA fragments over an order of magnitude larger than that with conventional restriction enzyme analysis. It provides a good representation of the entire bacterial chromosome in a single gel with a highly reproducible restriction profile, providing clearly distinct and well-resolved DNA fragments.
CONFORMANCE IMPROVEMENT USING GELS
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
Special symmetric quark mass matrices
NASA Astrophysics Data System (ADS)
Silva-Marcos, J. I.
1998-12-01
We give a procedure to construct a special class of symmetric quark mass matrices near the democratic limit of equal Yukawa couplings for each sector. It is shown that within appropriate weak-bases, the requirements of symmetry and arg[det(M)]=0 are very strong conditions, that necessarily lead to a Cabibbo angle given by Vus=sqrt(md/ms), and to Vcb~ms/mb, in first order. In addition, we prove that the recently classified ansätze, which also reproduce these mixing matrix relations, and which were based on the hypothesis of the Universal Strength for Yukawa couplings, where all Yukawa couplings have equal moduli while the flavour dependence is only in their phases, are, in fact, particular cases of the generalized symmetric quark mass matrix ansätze we construct here. In an excellent numerical example, the experimental values on all quark mixings and masses are accommodated, and the CP violation phase parameter is shown to be crucially dependent on the values of mu and Vus.
Community Detection for Correlation Matrices
NASA Astrophysics Data System (ADS)
MacMahon, Mel; Garlaschelli, Diego
2015-04-01
A challenging problem in the study of complex systems is that of resolving, without prior information, the emergent, mesoscopic organization determined by groups of units whose dynamical activity is more strongly correlated internally than with the rest of the system. The existing techniques to filter correlations are not explicitly oriented towards identifying such modules and can suffer from an unavoidable information loss. A promising alternative is that of employing community detection techniques developed in network theory. Unfortunately, this approach has focused predominantly on replacing network data with correlation matrices, a procedure that we show to be intrinsically biased because of its inconsistency with the null hypotheses underlying the existing algorithms. Here, we introduce, via a consistent redefinition of null models based on random matrix theory, the appropriate correlation-based counterparts of the most popular community detection techniques. Our methods can filter out both unit-specific noise and system-wide dependencies, and the resulting communities are internally correlated and mutually anticorrelated. We also implement multiresolution and multifrequency approaches revealing hierarchically nested subcommunities with "hard" cores and "soft" peripheries. We apply our techniques to several financial time series and identify mesoscopic groups of stocks which are irreducible to a standard, sectorial taxonomy; detect "soft stocks" that alternate between communities; and discuss implications for portfolio optimization and risk management.
Kerov's interlacing sequences and random matrices
NASA Astrophysics Data System (ADS)
Bufetov, Alexey
2013-11-01
To a N × N real symmetric matrix Kerov assigns a piecewise linear function whose local minima are the eigenvalues of this matrix and whose local maxima are the eigenvalues of its (N - 1) × (N - 1) submatrix. We study the scaling limit of Kerov's piecewise linear functions for Wigner and Wishart matrices. For Wigner matrices the scaling limit is given by the Verhik-Kerov-Logan-Shepp curve which is known from asymptotic representation theory. For Wishart matrices the scaling limit is also explicitly found, and we explain its relation to the Marchenko-Pastur limit spectral law.
Revisiting the texture zero neutrino mass matrices
NASA Astrophysics Data System (ADS)
Singh, Madan; Ahuja, Gulsheen; Gupta, Manmohan
2016-12-01
In the light of refined and large measurements of the reactor mixing angle θ, we have revisited the texture three- and two-zero neutrino mass matrices in the flavor basis. For Majorana neutrinos, it has been explicitly shown that all the texture three-zero mass matrices remain ruled out. Further, for both normal and inverted mass ordering, for the texture two-zero neutrino mass matrices one finds interesting constraints on the Dirac-like CP-violating phase δ and Majorana phases ρ and σ.
Random Matrices and Lyapunov Coefficients Regularity
NASA Astrophysics Data System (ADS)
Gallavotti, Giovanni
2017-02-01
Analyticity and other properties of the largest or smallest Lyapunov exponent of a product of real matrices with a "cone property" are studied as functions of the matrices entries, as long as they vary without destroying the cone property. The result is applied to stability directions, Lyapunov coefficients and Lyapunov exponents of a class of products of random matrices and to dynamical systems. The results are not new and the method is the main point of this work: it is is based on the classical theory of the Mayer series in Statistical Mechanics of rarefied gases.
[Basal cell carcinoma with matrical differentiation].
Goldman-Lévy, Gabrielle; Frouin, Eric; Soubeyran, Isabelle; Maury, Géraldine; Guillot, Bernard; Costes, Valérie
2015-04-01
Basal cell carcinoma with matrical differentiation is a very rare variant of basal cell carcinoma. To our knowledge, less than 30 cases have been reported. This tumor is composed of basaloid lobules showing a differentiation toward the pilar matrix cells. Recently, it has been demonstrated that beta-catenin would interfer with physiopathogenesis of matrical tumors, in particular pilomatricomas, but also basal cell carcinomas with matrical differentiation. This is a new case, with immunohistochemical and molecular analysis of beta-catenin, in order to explain its histogenesis.
Direct dialling of Haar random unitary matrices
NASA Astrophysics Data System (ADS)
Russell, Nicholas J.; Chakhmakhchyan, Levon; O’Brien, Jeremy L.; Laing, Anthony
2017-03-01
Random unitary matrices find a number of applications in quantum information science, and are central to the recently defined boson sampling algorithm for photons in linear optics. We describe an operationally simple method to directly implement Haar random unitary matrices in optical circuits, with no requirement for prior or explicit matrix calculations. Our physically motivated and compact representation directly maps independent probability density functions for parameters in Haar random unitary matrices, to optical circuit components. We go on to extend the results to the case of random unitaries for qubits.
The detection of hexavalent chromium by organically doped sol-gels
Wong, P.W.; Mackenzie, J.D.
1994-12-31
The sol-gel process can be used to produce porous inorganic matrices that are doped with organic molecules. These doped gels can be used as a quantitative method for the spectrophotometric determination of trace concentrations of metallic ions. For the detection of hexavalent chromium, malachite green was used as the dopant. Preliminary results indicate concentrations on the order of 5 ppb are detectable using this method.
NASA Astrophysics Data System (ADS)
Hillaris, A.; Bouratzis, C.; Nindos, A.
2016-08-01
We study the characteristics of moving type IV radio bursts that extend to hectometric wavelengths (interplanetary type IV or type {IV}_{{IP}} bursts) and their relationship with energetic phenomena on the Sun. Our dataset comprises 48 interplanetary type IV bursts observed with the Radio and Plasma Wave Investigation (WAVES) instrument onboard Wind in the 13.825 MHz - 20 kHz frequency range. The dynamic spectra of the Radio Solar Telescope Network (RSTN), the Nançay Decametric Array (DAM), the Appareil de Routine pour le Traitement et l' Enregistrement Magnetique de l' Information Spectral (ARTEMIS-IV), the Culgoora, Hiraso, and the Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN) Radio Spectrographs were used to track the evolution of the events in the low corona. These were supplemented with soft X-ray (SXR) flux-measurements from the Geostationary Operational Environmental Satellite (GOES) and coronal mass ejections (CME) data from the Large Angle and Spectroscopic Coronagraph (LASCO) onboard the Solar and Heliospheric Observatory (SOHO). Positional information of the coronal bursts was obtained by the Nançay Radioheliograph (NRH). We examined the relationship of the type IV events with coronal radio bursts, CMEs, and SXR flares. The majority of the events (45) were characterized as compact, their duration was on average 106 minutes. This type of events was, mostly, associated with M- and X-class flares (40 out of 45) and fast CMEs, 32 of these events had CMEs faster than 1000 km s^{-1}. Furthermore, in 43 compact events the CME was possibly subjected to reduced aerodynamic drag as it was propagating in the wake of a previous CME. A minority (three) of long-lived type {IV}_{{IP}} bursts was detected, with durations from 960 minutes to 115 hours. These events are referred to as extended or long duration and appear to replenish their energetic electron content, possibly from electrons escaping from the corresponding coronal
CONFORMANCE IMPROVEMENT USING GELS
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
Jha, Amit K.; Malik, Manisha S.; Farach-Carson, Mary C.; Duncan, Randall L.; Jia, Xinqiao
2010-01-01
We aimed to develop biomimetic hydrogel matrices that not only exhibit structural hierarchy and mechanical integrity, but also present biological cues in a controlled fashion. To this end, photocrosslinkable, hyaluronic acid (HA)-based hydrogel particles (HGPs) were synthesized via an inverse emulsion crosslinking process followed by chemical modification with glycidyl methacrylate (GMA). HA modified with GMA (HA-GMA) was employed as the soluble macromer. Macroscopic hydrogels containing covalently integrated hydrogel particles (HA-c-HGP) were prepared by radical polymerization of HA-GMA in the presence of crosslinkable HGPs. The covalent linkages between the hydrogel particles and the secondary HA matrix resulted in the formation of a diffuse, fibrilar interface around the particles. Compared to the traditional bulk gels synthesized by photocrosslinking of HA-GMA, these hydrogels exhibited a reduced sol fraction and a lower equilibrium swelling ratio. When tested under uniaxial compression, the HA-c-HGP gels were more pliable than the HA-p-HGP gels and fractured at higher strain than the HA-GMA gels. Primary bovine chondrocytes were photoencapsulated in the HA matrices with minimal cell damage. The 3D microenvironment created by HA-GMA and HA HGPs not only maintained the chondrocyte phenotype but also fostered the production of cartilage specific extracellular matrix. To further improve the biological activities of the HA-c-HGP gels, bone morphogenetic protein 2 (BMP-2) was loaded into the immobilized HGPs. BMP-2 was released from the HA-c-HGP gels in a controlled manner with reduced initial burst over prolonged periods of time. The HA-c-HGP gels are promising candidates for use as bioactive matrices for cartilage tissue engineering. PMID:20936090
Matsuura-Hachiya, Yuko; Arai, Koji Y; Muraguchi, Taichi; Sasaki, Tasuku; Nishiyama, Toshio
2017-03-07
Type IV collagen isolated from lens capsule without enzymatic treatment is known to form a gel under physiological condition and influences cellular activities. In case of human keratinocytes, the suppression of proliferation on reconstituted type IV collagen gels was reported in monolayer culture. In this study, we examined effects of type IV collagen isolated from porcine lens capsule on epidermal formation in human skin equivalents. Type IV collagen aggregates were prepared under the culture condition and the aggregates suppressed keratinocyte proliferation in monolayer culture as well as the culture on the gels. In human skin equivalents type IV collagen aggregates were reconstituted on the surface of contracted collagen gels containing human dermal fibroblasts and the keratinocytes were then cultured on the aggregates for 14 days. Interestingly, in human skin equivalents with type IV collagen aggregates, the BrdU-positive keratinocytes were increased and the thickness of the epidermal layer was around twice than that of control culture. Epidermal differentiation markers were expressed in the upper layer of the epidermis and the defined deposition of human basement membrane components were increased at the dermal-epidermal junction. These results indicate that the type IV collagen aggregates stimulate the proliferation of basal keratinocytes and improve the stratification of epidermal layers in human skin equivalents. This article is protected by copyright. All rights reserved.
ESTIMATION OF FUNCTIONALS OF SPARSE COVARIANCE MATRICES.
Fan, Jianqing; Rigollet, Philippe; Wang, Weichen
High-dimensional statistical tests often ignore correlations to gain simplicity and stability leading to null distributions that depend on functionals of correlation matrices such as their Frobenius norm and other ℓ r norms. Motivated by the computation of critical values of such tests, we investigate the difficulty of estimation the functionals of sparse correlation matrices. Specifically, we show that simple plug-in procedures based on thresholded estimators of correlation matrices are sparsity-adaptive and minimax optimal over a large class of correlation matrices. Akin to previous results on functional estimation, the minimax rates exhibit an elbow phenomenon. Our results are further illustrated in simulated data as well as an empirical study of data arising in financial econometrics.
ESTIMATION OF FUNCTIONALS OF SPARSE COVARIANCE MATRICES
Fan, Jianqing; Rigollet, Philippe; Wang, Weichen
2016-01-01
High-dimensional statistical tests often ignore correlations to gain simplicity and stability leading to null distributions that depend on functionals of correlation matrices such as their Frobenius norm and other ℓr norms. Motivated by the computation of critical values of such tests, we investigate the difficulty of estimation the functionals of sparse correlation matrices. Specifically, we show that simple plug-in procedures based on thresholded estimators of correlation matrices are sparsity-adaptive and minimax optimal over a large class of correlation matrices. Akin to previous results on functional estimation, the minimax rates exhibit an elbow phenomenon. Our results are further illustrated in simulated data as well as an empirical study of data arising in financial econometrics. PMID:26806986
Synchronous correlation matrices and Connes’ embedding conjecture
Dykema, Kenneth J.; Paulsen, Vern
2016-01-15
In the work of Paulsen et al. [J. Funct. Anal. (in press); preprint arXiv:1407.6918], the concept of synchronous quantum correlation matrices was introduced and these were shown to correspond to traces on certain C*-algebras. In particular, synchronous correlation matrices arose in their study of various versions of quantum chromatic numbers of graphs and other quantum versions of graph theoretic parameters. In this paper, we develop these ideas further, focusing on the relations between synchronous correlation matrices and microstates. We prove that Connes’ embedding conjecture is equivalent to the equality of two families of synchronous quantum correlation matrices. We prove that if Connes’ embedding conjecture has a positive answer, then the tracial rank and projective rank are equal for every graph. We then apply these results to more general non-local games.
CONFORMANCE IMPROVEMENT USING GELS
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
Decomposition of Balanced Matrices. Part 5: Goggles
1991-10-01
A D-A 247 462 Management Science Research Report #MSRR-573 1~ ~~112 Eil 11 I Decomposition of Balanced Matrices . Part V: Goggles Michele Conforti 12...9001705. I Dipartimento di Matematica Pura ed Applicata, UniversitA di Padova, Via Belzoni 7, 35131 Padova, Italy.f 2 Carnegie Mellon University...NUMBER 4. TITLE (and Subtitle) 5. TYPE OF REPORT & PERIOD COVERED DECOMPOSITION OF BALANCED MATRICES . Technical Report, Oct 1991 PART V: GOGGLES 6
Flux Jacobian Matrices For Equilibrium Real Gases
NASA Technical Reports Server (NTRS)
Vinokur, Marcel
1990-01-01
Improved formulation includes generalized Roe average and extension to three dimensions. Flux Jacobian matrices derived for use in numerical solutions of conservation-law differential equations of inviscid flows of ideal gases extended to real gases. Real-gas formulation of these matrices retains simplifying assumptions of thermodynamic and chemical equilibrium, but adds effects of vibrational excitation, dissociation, and ionization of gas molecules via general equation of state.
Computation of transform domain covariance matrices
NASA Technical Reports Server (NTRS)
Fino, B. J.; Algazi, V. R.
1975-01-01
It is often of interest in applications to compute the covariance matrix of a random process transformed by a fast unitary transform. Here, the recursive definition of fast unitary transforms is used to derive recursive relations for the covariance matrices of the transformed process. These relations lead to fast methods of computation of covariance matrices and to substantial reductions of the number of arithmetic operations required.
Fast Array Algorithms for Structured Matrices
1989-06-01
matrices and operators, Akademie-Verlag, Berlin, 1984. [111. T. Kailath , Linear Systems , Prentice-Hall, Englewood Cliffs, New Jersey, 1980. [121. T... Linear Systems Prentice-Hall, Englewood Cliffs, New Jersey, 1980. [131. T. Kailath, Signal processing in the VLSI era, VLSI and Modem Signal Processing...vol 5, No. 1., (1984), pp. 237-254. [11]. F. Gantmacher The theory of matrices, vol. 2, Chelsea Publishing Comp., New York, 1960. [121. T. Kailath
Block Lanczos tridiagonalization of complex symmetric matrices
NASA Astrophysics Data System (ADS)
Qiao, Sanzheng; Liu, Guohong; Xu, Wei
2005-08-01
The classic Lanczos method is an effective method for tridiagonalizing real symmetric matrices. Its block algorithm can significantly improve performance by exploiting memory hierarchies. In this paper, we present a block Lanczos method for tridiagonalizing complex symmetric matrices. Also, we propose a novel componentwise technique for detecting the loss of orthogonality to stablize the block Lanczos algorithm. Our experiments have shown our componentwise technique can reduce the number of orthogonalizations.
Infinite Products of Random Isotropically Distributed Matrices
NASA Astrophysics Data System (ADS)
Il'yn, A. S.; Sirota, V. A.; Zybin, K. P.
2017-01-01
Statistical properties of infinite products of random isotropically distributed matrices are investigated. Both for continuous processes with finite correlation time and discrete sequences of independent matrices, a formalism that allows to calculate easily the Lyapunov spectrum and generalized Lyapunov exponents is developed. This problem is of interest to probability theory, statistical characteristics of matrix T-exponentials are also needed for turbulent transport problems, dynamical chaos and other parts of statistical physics.
Lin, Canrong; Wang, Hongqing; Wang, Yuyuan; Cheng, Zhiqiang
2010-04-15
A new pyrazole derivative 1-phenyl-3-methylthio-4-cyano-5-acrylicacidcarbamoyl-pyrazole (PMTCAACP) was synthesized and chosen as a complexing monomer for the preparation of surface-grafted ion-imprinted polymers for selective solid-phase extraction of thorium(IV). The silica gel, modified with maleic anhydride, was prepared as a carrier material. In the ion-imprinting process, Th(IV) was complexed with PMTCAACP, and then imprinted in the polymers grafted to the surface of modified silica gel. Subsequently, the template Th(IV) ions were removed with 6 mol/L HCl solution. The obtained ion-imprinted particles for Th(IV) showed specific recognition, and rapid adsorption and desorption kinetics process. The maximum static and total dynamic adsorption capacity of the ion-imprinted polymers (IIPs) for Th(IV) was 64.8 and 37.4 mg/g, respectively. The relative selectivity coefficient values of the imprinted adsorbent for Th(IV)/U(VI), Th(IV)/Ce(III), Th(IV)/La(III), and Th(IV)/Zr(IV) were 72.9, 89.6, 93.8, and 137.2 times greater than non-imprinted matrix, respectively. The interference effect of common cations tested did not interfere with the recovery of Th(IV). The enhancement factor of 20.2, the detection limit of 0.43 microg/L, and the precision of 2.47% (n=7) of the method under the optimized conditions were obtained. Additionally, the calibration curve (r=0.9993) was linear in the range of 1.43-103 microg/L of thorium(IV). The prepared IIPs were shown to be promising for solid-phase extraction coupled with UV-vis spectrophotometry for determination of trace Th(IV) in real samples.
Drying SDS-Polyacrylamide Gels.
Sambrook, Joseph; Russell, David W
2006-09-01
INTRODUCTIONThis protocol describes a method for drying SDS-polyacrylamide gels. Gels containing proteins radiolabeled with (35)S-labeled amino acids must be dried before autoradiographic images can be obtained. Nonradioactive gels can also be preserved by drying.
ERIC Educational Resources Information Center
Pondy, Dorothy, Comp.
The catalog was compiled to assist instructors in planning community college and university curricula using the 48 computer-assisted accountancy lessons available on PLATO IV (Programmed Logic for Automatic Teaching Operation) for first semester accounting courses. It contains information on lesson access, lists of acceptable abbreviations for…
IVS Technology Coordinator Report
NASA Technical Reports Server (NTRS)
Whitney, Alan
2013-01-01
This report of the Technology Coordinator includes the following: 1) continued work to implement the new VLBI2010 system, 2) the 1st International VLBI Technology Workshop, 3) a VLBI Digital- Backend Intercomparison Workshop, 4) DiFX software correlator development for geodetic VLBI, 5) a review of progress towards global VLBI standards, and 6) a welcome to new IVS Technology Coordinator Bill Petrachenko.
ERIC Educational Resources Information Center
Stifle, Jack
The PLATO IV computer-based instructional system consists of a large scale centrally located CDC 6400 computer and a large number of remote student terminals. This is a brief and general description of the proposed input/output hardware necessary to interface the student terminals with the computer's central processing unit (CPU) using available…
ERIC Educational Resources Information Center
Kaiser, Henry F.; Rice, John
1974-01-01
In this paper three changes and one new development for the method of exploratory factor analysis (a second generation Little Jiffy) developed by Kaiser are described. Following this short description a step-by-step computer algorithm of the revised method, dubbed Little Jiffy, Mark IV is presented. (MP)
BMP-silk composite matrices heal critically sized femoral defects.
Kirker-Head, C; Karageorgiou, V; Hofmann, S; Fajardo, R; Betz, O; Merkle, H P; Hilbe, M; von Rechenberg, B; McCool, J; Abrahamsen, L; Nazarian, A; Cory, E; Curtis, M; Kaplan, D; Meinel, L
2007-08-01
Clinical drawbacks of bone grafting prompt the search for alternative bone augmentation technologies such as use of growth and differentiation factors, gene therapy, and cell therapy. Osteopromotive matrices are frequently employed for the local delivery and controlled release of these augmentation agents. Some matrices also provide an osteoconductive scaffold to support new bone growth. In this study, silkworm-derived silk fibroin was evaluated as an osteoconductive matrix for healing critical sized mid-femoral segmental defects in nude rats. Four treatment groups were assessed over eight weeks: silk scaffolds (SS) with recombinant human BMP-2 (rhBMP-2) and human mesenchymal stem cells (HMSC) that had been pre-differentiated along an osteoblastic lineage ex vivo (Group I; pdHMSC/rhBMP-2/SS); SS with rhBMP-2 and undifferentiated HMSCs (Group II; udHMSC/rhBMP-2/SS); SS and rhBMP-2 alone (Group III; rhBMP-2/SS); and empty defects (Group IV). Bi-weekly radiographs revealed a progressive and similar increase in Group I-III mean defect mineralization through post-operative week (POW) 8. Radiographs, dual energy x-ray absorptiometry, and micro-computed tomography confirmed that Groups I-III exhibited similar substantial and significantly (p<0.05) greater defect mineralization at POW 8 than the unfilled Group IV defects which remained void of bone. No significant differences in Groups I-III defect healing at POW 8 were apparent using these same assays or mechanical testing. Histology at POW 8 revealed moderately good bridging of the parent diaphyseal cortices with woven and lamellar bone bridging islands of silk matrix in Groups I and III. Group II defects possessed comparatively less new bone which was most abundant adjacent to the parent bone margins. Elsewhere the silk matrix was more often enveloped by poorly differentiated loose fibrous connective tissue. Group IV defects showed minimal new bone formation. None of the treatment groups attained the mean mineralization
Asare-Addo, Kofi; Levina, Marina; Rajabi-Siahboomi, Ali R; Nokhodchi, Ali
2010-12-01
In this article, the influence of agitation in descending and ascending sequences as a systematic method development process for potentially discriminating fed and fasted states and evaluation of its effects on the drug release from swelling gel-forming hydrophilic matrix tablets were investigated. Theophylline extended release (ER) matrices containing hypromellose (hydroxypropyl methylcellulose (HPMC)) were evaluated in media with a pH range of 1.2-7.5, using an automated USP type III, Bio-Dis dissolution apparatus at 5, 10, 15, 20, 25 and 30 dips per minute (dpm). Agitation had a profound effect on the drug release from the HPMC K100LV matrices. Drug release in pH 1.2 changed from about 40% at 5 dpm to about 80% at 30 dpm over a 60 min period alone. The matrices containing HPMC K4M, K15M and K100M however were not significantly affected by the agitation rate. The similarity factor f2 was calculated using drug release at 10 dpm as a reference. The ascending agitations of 5-30 dpm and the descending order of agitation 30-5 dpm were also evaluated. Anomalous transport was the only kinetic of release for the K4M, K15M and K100M tablet matrices. The lower viscous polymer of K100LV had some matrices exhibiting Fickian diffusion as its kinetics of release. The use of systematic change of agitation method may indicate potential fed and fasted effects on drug release from hydrophilic matrices.
A Brief Historical Introduction to Matrices and Their Applications
ERIC Educational Resources Information Center
Debnath, L.
2014-01-01
This paper deals with the ancient origin of matrices, and the system of linear equations. Included are algebraic properties of matrices, determinants, linear transformations, and Cramer's Rule for solving the system of algebraic equations. Special attention is given to some special matrices, including matrices in graph theory and electrical…
Smith, D R
1993-01-01
After digestion of DNA with a restriction enzyme (Chapter 50), it is usually necessary, for both preparative and analytical purposes, to separate and visualize the products. In most cases, where the products are between 200 and 20,000 bp long, this is achieved by agarose gel electrophoresis. Agarose is a linear polymer that is extracted from seaweed and sold as a white powder. The powder is melted in buffer and allowed to cool, whereby the agarose forms a gel by hydrogen bonding. The hardened matrix contains pores, the size of which depends on the concentration of agarose. The concentration of agarose is referred to as a percentage of agarose to volume of buffer (w/v), and agarose gels are normally in the range of 0.3 to 3%. Many different apparatus arrangements have been devised to run agarose gels; for example, they can be run horizontally or vertically, and the current can be conducted by wicks or the buffer solution. However, today, the "submarine" gel system is almost universally used. In this method, the agarose gel is formed on a supporting plate, and then the plate is submerged into a tank containing a suitable electrophoresis buffer. Wells are preformed in the agarose gel with the aid of a "comb" that is inserted into the cooling agarose before the agarose has gelled. Into these wells are loaded the sample to be analyzed, which has been mixed with a dense solution (a loading buffer) to ensure that the sample sinks into the wells.
Condition number estimation of preconditioned matrices.
Kushida, Noriyuki
2015-01-01
The present paper introduces a condition number estimation method for preconditioned matrices. The newly developed method provides reasonable results, while the conventional method which is based on the Lanczos connection gives meaningless results. The Lanczos connection based method provides the condition numbers of coefficient matrices of systems of linear equations with information obtained through the preconditioned conjugate gradient method. Estimating the condition number of preconditioned matrices is sometimes important when describing the effectiveness of new preconditionerers or selecting adequate preconditioners. Operating a preconditioner on a coefficient matrix is the simplest method of estimation. However, this is not possible for large-scale computing, especially if computation is performed on distributed memory parallel computers. This is because, the preconditioned matrices become dense, even if the original matrices are sparse. Although the Lanczos connection method can be used to calculate the condition number of preconditioned matrices, it is not considered to be applicable to large-scale problems because of its weakness with respect to numerical errors. Therefore, we have developed a robust and parallelizable method based on Hager's method. The feasibility studies are curried out for the diagonal scaling preconditioner and the SSOR preconditioner with a diagonal matrix, a tri-daigonal matrix and Pei's matrix. As a result, the Lanczos connection method contains around 10% error in the results even with a simple problem. On the other hand, the new method contains negligible errors. In addition, the newly developed method returns reasonable solutions when the Lanczos connection method fails with Pei's matrix, and matrices generated with the finite element method.
Condition Number Estimation of Preconditioned Matrices
Kushida, Noriyuki
2015-01-01
The present paper introduces a condition number estimation method for preconditioned matrices. The newly developed method provides reasonable results, while the conventional method which is based on the Lanczos connection gives meaningless results. The Lanczos connection based method provides the condition numbers of coefficient matrices of systems of linear equations with information obtained through the preconditioned conjugate gradient method. Estimating the condition number of preconditioned matrices is sometimes important when describing the effectiveness of new preconditionerers or selecting adequate preconditioners. Operating a preconditioner on a coefficient matrix is the simplest method of estimation. However, this is not possible for large-scale computing, especially if computation is performed on distributed memory parallel computers. This is because, the preconditioned matrices become dense, even if the original matrices are sparse. Although the Lanczos connection method can be used to calculate the condition number of preconditioned matrices, it is not considered to be applicable to large-scale problems because of its weakness with respect to numerical errors. Therefore, we have developed a robust and parallelizable method based on Hager’s method. The feasibility studies are curried out for the diagonal scaling preconditioner and the SSOR preconditioner with a diagonal matrix, a tri-daigonal matrix and Pei’s matrix. As a result, the Lanczos connection method contains around 10% error in the results even with a simple problem. On the other hand, the new method contains negligible errors. In addition, the newly developed method returns reasonable solutions when the Lanczos connection method fails with Pei’s matrix, and matrices generated with the finite element method. PMID:25816331
Cationized pullulan 3D matrices as new materials for gene transfer.
San Juan, Aurélie; Hlawaty, Hanna; Chaubet, Frédéric; Letourneur, Didier; Feldman, Laurent J
2007-08-01
This study deals with the development of a novel biocompatible cationized pullulan three-dimensional matrix for gene delivery. A water-soluble cationic polysaccharide, diethylaminoethyl-pullulan (DEAE-pullulan), was first synthesized and characterized. Fluorescence quenching and gel retardation assays evidenced the complexation in solution of DNA with DEAE-pullulan, but not with neutral pullulan. On cultured smooth muscle cells (SMCs) incubated with DEAE-pullulan and a plasmid vector expressing a secreted form of alkaline phosphatase (pSEAP), SEAP activity was 150-fold higher than with pSEAP alone or pSEAP with neutral pullulan. DEAE-pullulan was then chemically crosslinked using phosphorus oxychloride. The resulting matrices were obtained in less than a minute and molded as discs of 12 mm diameter and 2 mm thickness. Such DEAE-pullulan 3D matrices were loaded with up to 50 microg of plasmid DNA, with a homogeneous plasmid loading observed with YOYO-1 fluorescence staining. Moreover, the DEAE-pullulan matrix was shown to protect pSEAP from DNase I degradation. Incubation of cultured SMCs with pSEAP-loaded DEAE-pullulan matrices resulted in significant gene transfer without cell toxicity. This study suggests that these cationized pullulan 3D matrices could be useful biomaterials for local gene transfer.
Examination of light distribution from sol-gel based applicators for interstitial laser therapy
NASA Astrophysics Data System (ADS)
Hołowacz, I.; Ulatowska-Jarża, A.; Podbielska, H.; Garbaczewska, I.
2006-02-01
We describe here the construction of sol-gel based applicators for interstitial thermotheraphy. The silica sol-gel coatings were prepared from silicate precursor TEOS (tetraethylorthosilicate) mixed with ethyl alcohol in acid catalyzed hydrolysis. The matrices were produced with various ratios R=5, 10, 20, 32, 50, whereas R denotes the number of solvent molds (here ethanol) to the number of TEOS moles. The spatial light intensity distribution was examined in order to find out the influence of R factor on the light distribution shape. It was shows that the most homogeneous patterns are observed for sol-gel coatings with R factors equal 10 and 20.
Bayesian Nonparametric Clustering for Positive Definite Matrices.
Cherian, Anoop; Morellas, Vassilios; Papanikolopoulos, Nikolaos
2016-05-01
Symmetric Positive Definite (SPD) matrices emerge as data descriptors in several applications of computer vision such as object tracking, texture recognition, and diffusion tensor imaging. Clustering these data matrices forms an integral part of these applications, for which soft-clustering algorithms (K-Means, expectation maximization, etc.) are generally used. As is well-known, these algorithms need the number of clusters to be specified, which is difficult when the dataset scales. To address this issue, we resort to the classical nonparametric Bayesian framework by modeling the data as a mixture model using the Dirichlet process (DP) prior. Since these matrices do not conform to the Euclidean geometry, rather belongs to a curved Riemannian manifold,existing DP models cannot be directly applied. Thus, in this paper, we propose a novel DP mixture model framework for SPD matrices. Using the log-determinant divergence as the underlying dissimilarity measure to compare these matrices, and further using the connection between this measure and the Wishart distribution, we derive a novel DPM model based on the Wishart-Inverse-Wishart conjugate pair. We apply this model to several applications in computer vision. Our experiments demonstrate that our model is scalable to the dataset size and at the same time achieves superior accuracy compared to several state-of-the-art parametric and nonparametric clustering algorithms.
Conformance Improvement Using Gels
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.
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
Enhanced Design Alternative IV
N. E. Kramer
1999-05-18
This report evaluates Enhanced Design Alternative (EDA) IV as part of the second phase of the License Application Design Selection (LADS) effort. The EDA IV concept was compared to the VA reference design using criteria from the ''Design Input Request for LADS Phase II EDA Evaluations'' (CRWMS M&O 1999b) and (CRWMS M&O 1999f). Briefly, the EDA IV concept arranges the waste packages close together in an emplacement configuration known as ''line load''. Continuous pre-closure ventilation keeps the waste packages from exceeding the 350 C cladding and 200 C (4.3.13) drift wall temperature limits. This EDA concept keeps relatively high, uniform emplacement drift temperatures (post-closure) to drive water away from the repository and thus dry out the pillars between emplacement drifts. The waste package is shielded to permit human access to emplacement drifts and includes an integral filler inside the package to reduce the amount of water that can contact the waste form. Closure of the repository is desired 50 years after first waste is emplaced. Both backfill and a drip shields will be emplaced at closure to improve post-closure performance.
A general code to predict the drug release kinetics from different shaped matrices.
Barba, Anna Angela; d'Amore, Matteo; Chirico, Serafina; Lamberti, Gaetano; Titomanlio, Giuseppe
2009-02-15
This work deals with the modeling of drug release from solid pharmaceutical systems (matrices) for oral delivery. The attention was paid to the behavior of matrices made of hydrogels and drug, and the modeling was devoted to reproduce all the relevant phenomena (water up-take, gel swelling, diffusivity increase, drug diffusion and polymer erosion). Thus, the transient mass balances (for both drug and water), with the proper initial and boundary conditions were written, and a generalized numerical code was formulated; it is able to describe several geometries (slab, sphere, infinite and finite cylinders; this latter was done by an approximation which reduces the 2D problem to an 1D scheme). The main phenomena observed in drug delivery from hydrogel-based matrix, i.e. polymer swelling and erosion, were taken into account. The code was validated by comparison with analytical solutions, available for some simplified situation, and then it was tested with some experimental data taken from literature.
Sieving DNA molecules by length dependence in artificial nano-channel matrices
NASA Astrophysics Data System (ADS)
Wang, Chung-Hsuan; Hua Ho, Chia; Chou, Y. C.
2013-01-01
Nano-channel matrices are designed and fabricated for sieving DNA molecules by length. The length dependence is found to change with the size of the channels. Three regimes can be distinguished: (a) for the matrices with the size of the channels comparable to the persistence length (lp) of DNA molecules (45 nm), the mobility of DNA is found to decrease with the length of the molecules, similar to that found for the gel electrophoresis; (b) as the size of the nano-channel increases, the successful attacking frequency increases for the long molecules. The length-dependence of the mobility reverses; and (c) the Ogston mechanism holds for even larger channels. The short DNA molecules drift faster for the channels with diameter larger than 10 lp. Such a variety of the length dependence is observed for the first time in the electrophoresis in the artificial structures.
Maity, Siddhartha; Sa, Biswanath
2014-07-01
The effect of Ca(2+) ion concentration on swelling, erosion, and drug release mechanism of Ca(2+) ion cross-linked carboxymethyl xanthan gum (Ca-CMXG) matrices was investigated. By adding CaCl2 solution, carboxymethyl xanthan gum (CMXG) was converted into Ca-CMXG matrix, which was evaluated for swelling, erosion and drug release in different dissolution media. The amount of Ca(2+) ion alters the viscosity of gel layer formed around the matrices resulting in decreased water penetration into swollen layer. The changes in amount of Ca(2+) ion considerably influenced the swelling and erosion of the matrix leading to different drug release profiles. The simultaneous swelling and erosion of matrices that were controlled by the degree of cross-linking prejudiced the drug release mechanism. The release data fitted well into the Korsmeyer-Peppas equation and the combined effect of diffusion and erosion described the overall drug transport mechanism.
Does WISC-IV Underestimate the Intelligence of Autistic Children?
Nader, Anne-Marie; Courchesne, Valérie; Dawson, Michelle; Soulières, Isabelle
2016-05-01
Wechsler Intelligence Scale for Children (WISC) is widely used to estimate autistic intelligence (Joseph in The neuropsychology of autism. Oxford University Press, Oxford, 2011; Goldstein et al. in Assessment of autism spectrum disorders. Guilford Press, New York, 2008; Mottron in J Autism Dev Disord 34(1):19-27, 2004). However, previous studies suggest that while WISC-III and Raven's Progressive Matrices (RPM) provide similar estimates of non-autistic intelligence, autistic children perform significantly better on RPM (Dawson et al. in Psychol Sci 18(8):657-662, doi: 10.1111/j.1467-9280.2007.01954.x , 2007). The latest WISC version introduces substantial changes in subtests and index scores; thus, we asked whether WISC-IV still underestimates autistic intelligence. Twenty-five autistic and 22 typical children completed WISC-IV and RPM. Autistic children's RPM scores were significantly higher than their WISC-IV FSIQ, but there was no significant difference in typical children. Further, autistic children showed a distinctively uneven WISC-IV index profile, with a "peak" in the new Perceptual Reasoning Index. In spite of major changes, WISC-IV FSIQ continues to underestimate autistic intelligence.
Advanced incomplete factorization algorithms for Stiltijes matrices
Il`in, V.P.
1996-12-31
The modern numerical methods for solving the linear algebraic systems Au = f with high order sparse matrices A, which arise in grid approximations of multidimensional boundary value problems, are based mainly on accelerated iterative processes with easily invertible preconditioning matrices presented in the form of approximate (incomplete) factorization of the original matrix A. We consider some recent algorithmic approaches, theoretical foundations, experimental data and open questions for incomplete factorization of Stiltijes matrices which are {open_quotes}the best{close_quotes} ones in the sense that they have the most advanced results. Special attention is given to solving the elliptic differential equations with strongly variable coefficients, singular perturbated diffusion-convection and parabolic equations.
PRM: A database of planetary reflection matrices
NASA Astrophysics Data System (ADS)
Stam, D. M.; Batista, S. F. A.
2014-04-01
We present the PRM database with reflection matrices of various types of planets. With the matrices, users can calculate the total, and the linearly and circularly polarized fluxes of incident unpolarized light that is reflected by a planet for arbitrary illumination and viewing geometries. To allow for flexibility in these geometries, the database does not contain the elements of reflection matrices, but the coefficients of their Fourier series expansion. We describe how to sum these coefficients for given illumination and viewing geometries to obtain the local reflection matrix. The coefficients in the database can also be used to calculate flux and polarization signals of exoplanets, by integrating, for a given planetary phase angle, locally reflected fluxes across the visible part of the planetary disk. Algorithms for evaluating the summation for locally reflected fluxes, as applicable to spatially resolved observations of planets, and the subsequent integration for the disk-integrated fluxes, as applicable to spatially unresolved exoplanets are also in the database
NASA Astrophysics Data System (ADS)
Lundquist, Charles A.
2009-12-01
The Sputnik IV launch occurred on May 15, 1960. On May 19, an attempt to deorbit a 'space cabin' failed and the cabin went into a higher orbit. The orbit of the cabin was monitored and Moonwatch volunteer satellite tracking teams were alerted to watch for the vehicle demise. On September 5, 1962, several team members from Milwaukee, Wisconsin made observations starting at 4:49 a.m. of a fireball following the predicted orbit of Sputnik IV. Requests went out to report any objects found under the fireball path. An early morning police patrol in Manitowoc had noticed a metal object on a street and had moved it to the curb. Later the officers recovered the object and had it dropped off at the Milwaukee Journal. The Moonwarch team got the object and reported the situation to Moonwatch Headquarters at the Smithsonian Astrophysical Observatory. A team member flew to Cambridge with the object. It was a solid, 9.49 kg piece of steel with a slag-like layer attached to it. Subsequent analyses showed that it contained radioactive nuclei produced by cosmic ray exposure in space. The scientists at the Observatory quickly recognized that measurements of its induced radioactivity could serve as a calibration for similar measurements of recently fallen nickel-iron meteorites. Concurrently, the Observatory directorate informed government agencies that a fragment from Sputnik IV had been recovered. Coincidently, a debate in the UN Committee on Peaceful Uses of Outer Space involved the issue of liability for damage caused by falling satellite fragments. On September 12, the Observatory delivered the bulk of the fragment to the US Delegation to the UN. Two days later, the fragment was used by US Ambassador Francis Plimpton as an exhibit that the time had come to agree on liability for damage from satellite debris. He offered the Sputnik IV fragment to USSR Ambassador P.D. Morozov, who refused the offer. On October 23, Drs. Alla Massevitch and E.K. Federov of the USSR visited the
NASA Astrophysics Data System (ADS)
Kulikov, S. G.; Veret-Lemarinier, A. V.; Galaup, J. P.; Chaput, F.; Boilot, J. P.
1997-03-01
Pure inorganic sol-gel matrices as well as hybrid organic/inorganic xerogels have been doped with porphyrins derivatives and studied using line narrowing techniques. The role of residual hydroxyl groups is investigated. Free-base porphyrins are protonated in pure inorganic hosts, but the matrix acidity is reduced in hybrid matrices or when fluorinated porphyrins derivatives are used. The linear electron-phonon coupling can be controlled with the choice of the organic group in organic/inorganic matrices. Persistent spectral hole widths increase with temperature according a glass-like Tn dependence and evidence of spectral diffusion is shown in one of these systems.
Sparse Matrices in MATLAB: Design and Implementation
NASA Technical Reports Server (NTRS)
Gilbert, John R.; Moler, Cleve; Schreiber, Robert
1992-01-01
The matrix computation language and environment MATLAB is extended to include sparse matrix storage and operations. The only change to the outward appearance of the MATLAB language is a pair of commands to create full or sparse matrices. Nearly all the operations of MATLAB now apply equally to full or sparse matrices, without any explicit action by the user. The sparse data structure represents a matrix in space proportional to the number of nonzero entries, and most of the operations compute sparse results in time proportional to the number of arithmetic operations on nonzeros.
Balanced 0, + or - Matrices. Part 1. Decomposition,
1994-01-22
AD-A278 170 Management Science Research Report Number *600 Balanced 0, ± Matrices Part 1: DecompositionDTIC~ SD’.I.CT 1 Michele Conforti:. F I, ECTE...G6rard CornuJ6jgsQE R15� Ajai Kapuur 00 P 1 4 Kristina Vuskovic U F January 22, 1994 Dipartimento di Matematica Pura ed Applicata Universiti di...two nonzero entries per row and column, the sum of the entries is a multiple of four. This paper extends the decomposition of balanced 0, 1 matrices
Partitioning sparse rectangular matrices for parallel processing
Kolda, T.G.
1998-05-01
The authors are interested in partitioning sparse rectangular matrices for parallel processing. The partitioning problem has been well-studied in the square symmetric case, but the rectangular problem has received very little attention. They will formalize the rectangular matrix partitioning problem and discuss several methods for solving it. They will extend the spectral partitioning method for symmetric matrices to the rectangular case and compare this method to three new methods -- the alternating partitioning method and two hybrid methods. The hybrid methods will be shown to be best.
Oligonucleotide formation catalyzed by mononucleotide matrices
NASA Technical Reports Server (NTRS)
Lohrmann, R.
1982-01-01
Pb(2+)-containing precipitates of mononucleotides form matrices which catalyze the self-condensation of nucleotide 5-prime-phosphorimidazolides and their condensation with nucleosides. The reactions exhibit base-pairing specificity between matrix nucleotide and substrate, and usually follow the Watson-Crick pairing rules. Although purine polynucleotides do not facilitate the oligomerization of pyrimidine nucleotide monomers in solution, it is interesting that purine-containing matrices do catalyze such a reaction. The significance of the results in the context of the prebiotic evolution of polynucleotides is discussed.
CONFORMANCE IMPROVEMENT USING GELS
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.
Cell patterning on biological gels via cell spraying through a mask.
Nahmias, Yaakov; Arneja, Abhinav; Tower, Theodore T; Renn, Michael J; Odde, David J
2005-01-01
We present an easily applicable and inexpensive method for patterning cells on arbitrary surfaces including biological gels with little loss of viability or function. Single-cell suspensions of human umbilical vein endothelial cells and NIH 3T3 fibroblasts were sprayed with an off-the-shelf airbrush through a mask to create 100-microm scale patterns on collagen gels. Three-dimensional patterns were created by layering a collagen gel on top of the first pattern and patterning the top gel. Coculture of rat hepatocytes with NIH 3T3 patterns on collagen gels resulted in localized increased activity of cytochrome P-450 along the pattern. These results suggest that cell spraying is a useful tool for the study of heterotypic cellular interactions and tissue-engineering applications on biologically relevant matrices, and for the creation of three-dimensional cell patterns in vitro.
Solute partitioning and filtration by extracellular matrices
Hofmann, Christina L.; Ferrell, Nicholas; Schnell, Lisa; Dubnisheva, Anna; Zydney, Andrew L.; Yurchenco, Peter D.; Roy, Shuvo
2009-01-01
The physiology of glomerular filtration remains mechanistically obscure despite its importance in disease. The correspondence between proteinuria and foot process effacement suggests podocytes as the locus of the filtration barrier. If so, retained macromolecules ought to accumulate at the filtration barrier, an effect called concentration polarization. Literature data indicate macromolecule concentrations decrease from subendothelial to subepithelial glomerular basement membrane (GBM), as would be expected if the GBM were itself the filter. The objective of this study was to obtain insights into the possible role of the GBM in protein retention by performing fundamental experimental and theoretical studies on the properties of three model gels. Solute partitioning and filtration through thin gels of a commercially available laminin-rich extracellular matrix, Matrigel, were measured using a polydisperse polysaccharide tracer molecule, Ficoll 70. Solute partitioning into laminin gels and lens basement membrane (LBM) were measured using Ficoll 70. A novel model of a laminin gel was numerically simulated, as well as a mixed structure-random-fiber model for LBM. Experimental partitioning was predicted by numerical simulations. Sieving coefficients through thin gels of Matrigel were size dependent and strongly flux dependent. The observed flux dependence arose from compression of the gel in response to the applied pressure. Gel compression may alter solute partitioning into extracellular matrix at physiologic pressures present in the glomerular capillary. This suggests a physical mechanism coupling podocyte structure to permeability characteristics of the GBM. PMID:19587146
NASA Technical Reports Server (NTRS)
Tornatore, Vincenza
2013-01-01
The main activities carried out at the PMD (Politecnico di Milano DIIAR) IVS Analysis Center during 2012 are briefly higlighted, and future plans for 2013 are sketched out. We principally continued to process European VLBI sessions using different approaches to evaluate possible differences due to various processing choices. Then VLBI solutions were also compared to the GPS ones as well as the ones calculated at co-located sites. Concerning the observational aspect, several tests were performed to identify the most suitable method to achieve the highest possible accuracy in the determination of GNSS (GLOBAL NAVIGATION SATELLITE SYSTEM) satellite positions using the VLBI technique.
Circulant Matrices and Time-Series Analysis
ERIC Educational Resources Information Center
Pollock, D. S. G.
2002-01-01
This paper sets forth some salient results in the algebra of circulant matrices which can be used in time-series analysis. It provides easy derivations of some results that are central to the analysis of statistical periodograms and empirical spectral density functions. A statistical test for the stationarity or homogeneity of empirical processes…
SPECIATION OF ARSENIC IN EXPOSURE ASSESSMENT MATRICES
The speciaton of arsenic in water, food and urine are analytical capabilities which are an essential part in arsenic risk assessment. The cancer risk associated with arsenic has been the driving force in generating the analytical research in each of these matrices. This presentat...
Constructing random matrices to represent real ecosystems.
James, Alex; Plank, Michael J; Rossberg, Axel G; Beecham, Jonathan; Emmerson, Mark; Pitchford, Jonathan W
2015-05-01
Models of complex systems with n components typically have order n(2) parameters because each component can potentially interact with every other. When it is impractical to measure these parameters, one may choose random parameter values and study the emergent statistical properties at the system level. Many influential results in theoretical ecology have been derived from two key assumptions: that species interact with random partners at random intensities and that intraspecific competition is comparable between species. Under these assumptions, community dynamics can be described by a community matrix that is often amenable to mathematical analysis. We combine empirical data with mathematical theory to show that both of these assumptions lead to results that must be interpreted with caution. We examine 21 empirically derived community matrices constructed using three established, independent methods. The empirically derived systems are more stable by orders of magnitude than results from random matrices. This consistent disparity is not explained by existing results on predator-prey interactions. We investigate the key properties of empirical community matrices that distinguish them from random matrices. We show that network topology is less important than the relationship between a species' trophic position within the food web and its interaction strengths. We identify key features of empirical networks that must be preserved if random matrix models are to capture the features of real ecosystems.
Noisy covariance matrices and portfolio optimization
NASA Astrophysics Data System (ADS)
Pafka, S.; Kondor, I.
2002-05-01
According to recent findings [#!bouchaud!#,#!stanley!#], empirical covariance matrices deduced from financial return series contain such a high amount of noise that, apart from a few large eigenvalues and the corresponding eigenvectors, their structure can essentially be regarded as random. In [#!bouchaud!#], e.g., it is reported that about 94% of the spectrum of these matrices can be fitted by that of a random matrix drawn from an appropriately chosen ensemble. In view of the fundamental role of covariance matrices in the theory of portfolio optimization as well as in industry-wide risk management practices, we analyze the possible implications of this effect. Simulation experiments with matrices having a structure such as described in [#!bouchaud!#,#!stanley!#] lead us to the conclusion that in the context of the classical portfolio problem (minimizing the portfolio variance under linear constraints) noise has relatively little effect. To leading order the solutions are determined by the stable, large eigenvalues, and the displacement of the solution (measured in variance) due to noise is rather small: depending on the size of the portfolio and on the length of the time series, it is of the order of 5 to 15%. The picture is completely different, however, if we attempt to minimize the variance under non-linear constraints, like those that arise e.g. in the problem of margin accounts or in international capital adequacy regulation. In these problems the presence of noise leads to a serious instability and a high degree of degeneracy of the solutions.
Universal portfolios generated by Toeplitz matrices
NASA Astrophysics Data System (ADS)
Tan, Choon Peng; Chu, Sin Yen; Pan, Wei Yeing
2014-06-01
Performance of universal portfolios generated by Toeplitz matrices is studied in this paper. The general structure of the companion matrix of the generating Toeplitz matrix is determined. Empirical performance of the threeband and nine-band Toeplitz universal portfolios on real stock data is presented. Pseudo Toeplitz universal portfolios are studied with promising empirical achievement of wealth demonstrated.
Study of the critical points of HPMC hydrophilic matrices for controlled drug delivery.
Miranda, Antonia; Millán, Mónica; Caraballo, Isidoro
2006-03-27
The knowledge of the percolation thresholds of a system results in a clear improvement of the design of controlled release dosage forms such as inert matrices. Despite hydrophilic matrices are one of the most used controlled delivery systems in the world, but actuality, the mechanisms of drug release from these systems continue to be a matter of debate nowadays. The objective of the present paper is to apply the percolation theory to study the release and hydration rate of hydrophilic matrices. Matrix tablets have been prepared using KCl as a drug model and HPMC K4M as matrix-forming material, employing five different excipient/drug particle size ratios (ranging from 0.42 to 2.33). The formulations studied containing a drug loading in the range of 20-90% (w/w). Dissolution studies were carried out using the paddle method and the water uptake measurements were performed using a modified Enslin apparatus. In order to estimate the percolation threshold, the behaviour of the kinetic parameters with respect to the volumetric fraction of each component at time zero, was studied. The percolation theory has been applied for the first time to the study of matrix type controlled delivery systems. The application of this theory allowed to explain changes in the release and hydration kinetics of these matrices. The critical points observed in dissolution and water uptake studies can be attributed to the excipient percolation threshold, being this threshold one of the main factors governing the gel layer formation and consequently, the drug release control from hydrophilic matrices.
Spatially resolved multicomponent gels
NASA Astrophysics Data System (ADS)
Draper, Emily R.; Eden, Edward G. B.; McDonald, Tom O.; Adams, Dave J.
2015-10-01
Multicomponent supramolecular systems could be used to prepare exciting new functional materials, but it is often challenging to control the assembly across multiple length scales. Here we report a simple approach to forming patterned, spatially resolved multicomponent supramolecular hydrogels. A multicomponent gel is first formed from two low-molecular-weight gelators and consists of two types of fibre, each formed by only one gelator. One type of fibre in this ‘self-sorted network’ is then removed selectively by a light-triggered gel-to-sol transition. We show that the remaining network has the same mechanical properties as it would have done if it initially formed alone. The selective irradiation of sections of the gel through a mask leads to the formation of patterned multicomponent networks, in which either one or two networks can be present at a particular position with a high degree of spatial control.
NASA Astrophysics Data System (ADS)
Matsuo, Eriko Sato; Tanaka, Toyoichi
1992-08-01
POLYMER gels can undergo a volume phase transition (either continuous or discontinuous) when an external condition, such as temperature or solvent composition, is altered1-3. During this transition, the volume may change by a factor of several thousand, and various patterns develop in the gel. The patterns arising from swelling and shrinking differ in both their appearance and their physical mechanisms. The mechanism for the formation and evolution of patterns on swelling gels has been established as being due to a single kind of mechanical instability4-7 in contrast, the shrinking patterns seem to be sensitive to both the initial and final states of the transition. Here we classify the various shrinking patterns in the form of a phase diagram, and explain the poly-morphism in terms of macroscopic phase separation.
Kefiran-alginate gel microspheres for oral delivery of ciprofloxacin.
Blandón, Lina M; Islan, German A; Castro, Guillermo R; Noseda, Miguel D; Thomaz-Soccol, Vanete; Soccol, Carlos R
2016-09-01
Ciprofloxacin is a broad-spectrum antibiotic associated with gastric and intestinal side effects after extended oral administration. Alginate is a biopolymer commonly employed in gel synthesis by ionotropic gelation, but unstable in the presence of biological metal-chelating compounds and/or under dried conditions. Kefiran is a microbial biopolymer able to form gels with the advantage of displaying antimicrobial activity. In the present study, kefiran-alginate gel microspheres were developed to encapsulate ciprofloxacin for antimicrobial controlled release and enhanced bactericidal effect against common pathogens. Scanning electron microscopy (SEM) analysis of the hybrid gel microspheres showed a spherical structure with a smoother surface compared to alginate gel matrices. In vitro release of ciprofloxacin from kefiran-alginate microspheres was less than 3.0% and 5.0% at pH 1.2 (stomach), and 5.0% and 25.0% at pH 7.4 (intestine) in 3 and 21h, respectively. Fourier transform infrared spectroscopy (FTIR) of ciprofloxacin-kefiran showed the displacement of typical bands of ciprofloxacin and kefiran, suggesting a cooperative interaction by hydrogen bridges between both molecules. Additionally, the thermal analysis of ciprofloxacin-kefiran showed a protective effect of the biopolymer against ciprofloxacin degradation at high temperatures. Finally, antimicrobial assays of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhymurium, and Staphylococcus aureus demonstrated the synergic effect between ciprofloxacin and kefiran against the tested microorganisms.
Ethanol production using immobilized Saccharomyces cerevisiae in lyophilized cellulose gel.
Winkelhausen, Eleonora; Velickova, Elena; Amartey, Samuel A; Kuzmanova, Slobodanka
2010-12-01
A new lyophilization technique was used for immobilization of Saccharomyces cerevisiae cells in hydroxyethylcellulose (HEC) gels. The suitability of the lyophilized HEC gels to serve as immobilization matrices for the yeast cells was assessed by calculating the immobilization efficiency and the cell retention in three consecutive batches, each in duration of 72 h. Throughout the repeated batch fermentation, the immobilization efficiency was almost constant with an average value of 0.92 (12-216 h). The maximum value of cell retention was 0.24 g immobilized cells/g gel. Both parameters indicated that lyophilized gels are stable and capable of retaining the immobilized yeast cells. Showing the yeast cells propagation within the polymeric matrix, the scanning electron microscope images also confirmed that the lyophilization technique for immobilization of S. cerevisiae cells in the HEC gels was successful. The activity of the immobilized yeast cells was demonstrated by their capacity to convert glucose to ethanol. Ethanol yield of 0.40, 0.43 and 0.30 g ethanol/g glucose corresponding to 79%, 84% and 60% of the theoretical yield was attained in the first, second and third batches, respectively. The cell leakage was less than 10% of the average concentration of the immobilized cells.
The effects of autologous platelet gel on wound healing.
Henderson, Jenifer L; Cupp, Craig L; Ross, E Victor; Shick, Paul C; Keefe, Michael A; Wester, Derin C; Hannon, Timothy; McConnell, Devin
2003-08-01
Laser resurfacing techniques have become a popular means of achieving rejuvenation of damaged skin. Interest is great in attempting to speed re-epithelialization and healing so that patients can return to their normal activities as quickly as possible. Previous studies have demonstrated that wounds heal more quickly when they are covered and kept moist than when they are left open to the air. Until now, no study has been conducted to investigate whether the healing process of a superficial skin burn might be accelerated by the use of an autologous platelet gel as a biologic dressing. Our study of five pigs showed that autologous platelet gel can influence wound healing by stimulating an intense inflammatory process that leads to highly significant increases in the production of extracellular matrices and granulation tissue. The platelet gel accelerated vascular ingrowth, increased fibroblastic proliferation, and accelerated collagen production. However, the gel did not appear to accelerate re-epithelialization. The aggressive production of granulation tissue and the acceleration of collagen production might mean that autologous platelet gel will have a future role in the treatment of burns because the highly vascularized bed it helps create should promote the success of skin grafting in patients with deep partial-thickness and full-thickness burns.
NASA Astrophysics Data System (ADS)
Corbally, Christopher; D'Antona, Francesca; Spite, Monique; Asplund, Martin; Charbonnel, Corinne; Docobo, Jose Angel; Gray, Richard O.; Piskunov, Nikolai E.
2012-04-01
This Division IV was started on a trial basis at the General Assembly in The Hague 1994 and was formally accepted at the Kyoto General Assembly in 1997. Its broad coverage of ``Stars'' is reflected in its relatively large number of Commissions and so of members (1266 in late 2011). Its kindred Division V, ``Variable Stars'', has the same history of its beginning. The thinking at the time was to achieve some kind of balance between the number of members in each of the 12 Divisions. Amid the current discussion of reorganizing the number of Divisions into a more compact form it seems advisable to make this numerical balance less of an issue than the rationalization of the scientific coverage of each Division, so providing more effective interaction within a particular field of astronomy. After all, every star is variable to a certain degree and such variability is becoming an ever more powerful tool to understand the characteristics of every kind of normal and peculiar star. So we may expect, after hearing the reactions of members, that in the restructuring a single Division will result from the current Divisions IV and V.
Electroblotting from Polyacrylamide Gels.
Goldman, Aaron; Ursitti, Jeanine A; Mozdzanowski, Jacek; Speicher, David W
2015-11-02
Transferring proteins from polyacrylamide gels onto retentive membranes is now primarily used for immunoblotting. A second application that was quite common up to about a decade ago was electroblotting of proteins for N-terminal and internal sequencing using Edman chemistry. This unit contains procedures for electroblotting proteins from polyacrylamide gels onto a variety of membranes, including polyvinylidene difluoride (PVDF) and nitrocellulose. In addition to the commonly used tank or wet transfer system, protocols are provided for electroblotting using semidry and dry systems. This unit also describes procedures for eluting proteins from membranes using detergents or acidic extraction with organic solvents for specialized applications.
Chlorate analyses in matrices of animal origin.
Smith, David J; Taylor, Joshua B
2011-03-09
Sodium chlorate is being developed as a potential food-safety tool for use in the livestock industry because of its effectiveness in decreasing concentrations of certain Gram-negative pathogens in the gastrointestinal tracts of food animals. A number of studies with sodium chlorate in animals have demonstrated that concentrations of chlorate in meat, milk, wastes, and gastrointestinal contents range from parts per billion to parts per thousand, depending upon chlorate dose, matrix, and time lapse after dosing. Although a number of analytical methods exist for chlorate salts, very few were developed for use in animal-derived matrices, and none have anticipated the range of chlorate concentrations that have been observed in animal wastes and products. To meet the analytical needs of this development work, LC-MS, ion chromatographic, and colorimetric methods were developed to measure chlorate residues in a variety of matrices. The LC-MS method utilizes a Cl(18)O(3)(-) internal standard, is applicable to a variety of matrices, and provides quantitative assessment of samples from 0.050 to 2.5 ppm. Due to ion suppression, matrix-matched standard curves are appropriate when using LC-MS to measure chlorate in animal-derived matrices. A colorimetric assay based on the acid-catalyzed oxidation of o-tolidine proved valuable for measuring ≥20 ppm quantities of chlorate in blood serum and milk, but not urine, samples. Ion chromatography was useful for measuring chlorate residues in urine and in feces when chlorate concentrations exceeded 100 ppm, but no effort was made to maximize ion chromatographic sensitivity. Collectively, these methods offer the utility of measuring chlorate in a variety of animal-derived matrices over a wide range of chlorate concentrations.
2009-01-01
2009 Recommended by Enrico Capobianco This paper considers the lower and upper bounds of eigenvalues of arrow-head matrices. We propose a parameterized...arrowhead matrices have been used to describe radiationless transitions in isolated molecules [1] and oscillators vibrationally coupled with a Fermi ...Journal of Chemical Physics, vol. 48, no. 2, pp. 715– 726, 1968. [2] J. W. Gadzuk, “Localized vibrational modes in Fermi liquids. General theory
Federal Register 2010, 2011, 2012, 2013, 2014
2013-01-11
... Energy Regulatory Commission CSOLAR IV South, LLC, Wistaria Ranch Solar, LLC, CSOLAR IV West, LLC, CSOLAR IV North, LLC v. California Independent System Operator Corporation; Notice of Complaint Take notice... IV South, LLC, Wistaria Ranch Solar, LLC, CSOLAR IV West, LLC and CSOLAR IV North, LLC...
Gravitational compression of colloidal gels
NASA Astrophysics Data System (ADS)
Liétor-Santos, J. J.; Kim, C.; Lu, P. J.; Fernández-Nieves, A.; Weitz, D. A.
2009-02-01
We study the compression of depletion gels under the influence of a gravitational stress by monitoring the time evolution of the gel interface and the local volume fraction, φ , inside the gel. We find φ is not constant throughout the gel. Instead, there is a volume fraction gradient that develops and grows along the gel height as the compression process proceeds. Our results are correctly described by a non-linear poroelastic model that explicitly incorporates the φ -dependence of the gravitational, elastic and viscous stresses acting on the gel.
A test of the conjecture that G-matrices are more stable than B-matrices.
Barker, Brittany S; Phillips, Patrick C; Arnold, Stevan J
2010-09-01
The G-matrix occupies an important position in evolutionary biology both as a summary of the inheritance of quantitative traits and as an ingredient in predicting how those traits will respond to selection and drift. Consequently, the stability of G has an important bearing on the accuracy of predicted evolutionary trajectories. Furthermore, G should evolve in response to stable features of the adaptive landscape and their trajectories through time. Although the stability and evolution of G might be predicted from knowledge of selection in natural populations, most empirical comparisons of G-matrices have been made in the absence of such a priori predictions. We present a theoretical argument that within-sex G-matrices should be more stable than between-sex B-matrices because they are more powerfully exposed to multivariate stabilizing selection. We tested this conjecture by comparing estimates of B- and within-sex G-matrices among three populations of the garter snake Thamnophis elegans. Matrix comparisons using Flury's hierarchical approach revealed that within-sex G-matrices had four principal components in common (full CPC), whereas B-matrices had only a single principal component in common and eigenvalues that were more variable among populations. These results suggest that within-sex G is more stable than B, as predicted by our theoretical argument.
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.
Decision Matrices: Tools to Enhance Middle School Engineering Instruction
ERIC Educational Resources Information Center
Gonczi, Amanda L.; Bergman, Brenda G.; Huntoon, Jackie; Allen, Robin; McIntyre, Barb; Turner, Sheri; Davis, Jen; Handler, Rob
2017-01-01
Decision matrices are valuable engineering tools. They allow engineers to objectively examine solution options. Decision matrices can be incorporated in K-12 classrooms to support authentic engineering instruction. In this article we provide examples of how decision matrices have been incorporated into 6th and 7th grade classrooms as part of an…
Improved Separability Criteria Based on Bloch Representation of Density Matrices
Shen, Shu-Qian; Yu, Juan; Li, Ming; Fei, Shao-Ming
2016-01-01
The correlation matrices or tensors in the Bloch representation of density matrices are encoded with entanglement properties. In this paper, based on the Bloch representation of density matrices, we give some new separability criteria for bipartite and multipartite quantum states. Theoretical analysis and some examples show that the proposed criteria can be more efficient than the previous related criteria. PMID:27350031
19 CFR 10.90 - Master records and metal matrices.
Code of Federal Regulations, 2012 CFR
2012-04-01
... 19 Customs Duties 1 2012-04-01 2012-04-01 false Master records and metal matrices. 10.90 Section... Master Records, and Metal Matrices § 10.90 Master records and metal matrices. (a) Consumption entries... made, of each master record or metal matrix covered thereby. (c) A bond on Customs Form 301,...
19 CFR 10.90 - Master records and metal matrices.
Code of Federal Regulations, 2010 CFR
2010-04-01
... 19 Customs Duties 1 2010-04-01 2010-04-01 false Master records and metal matrices. 10.90 Section... Master Records, and Metal Matrices § 10.90 Master records and metal matrices. (a) Consumption entries... made, of each master record or metal matrix covered thereby. (c) A bond on Customs Form 301,...
19 CFR 10.90 - Master records and metal matrices.
Code of Federal Regulations, 2013 CFR
2013-04-01
... 19 Customs Duties 1 2013-04-01 2013-04-01 false Master records and metal matrices. 10.90 Section... Master Records, and Metal Matrices § 10.90 Master records and metal matrices. (a) Consumption entries... made, of each master record or metal matrix covered thereby. (c) A bond on Customs Form 301,...
19 CFR 10.90 - Master records and metal matrices.
Code of Federal Regulations, 2011 CFR
2011-04-01
... 19 Customs Duties 1 2011-04-01 2011-04-01 false Master records and metal matrices. 10.90 Section... Master Records, and Metal Matrices § 10.90 Master records and metal matrices. (a) Consumption entries... made, of each master record or metal matrix covered thereby. (c) A bond on Customs Form 301,...
19 CFR 10.90 - Master records and metal matrices.
Code of Federal Regulations, 2014 CFR
2014-04-01
... 19 Customs Duties 1 2014-04-01 2014-04-01 false Master records and metal matrices. 10.90 Section... Master Records, and Metal Matrices § 10.90 Master records and metal matrices. (a) Consumption entries... made, of each master record or metal matrix covered thereby. (c) A bond on Customs Form 301,...
Nayak, Sunita; Dey, Sancharika; Kundu, Subhas C
2013-01-01
The development of effective and alternative tissue-engineered skin replacements to autografts, allografts and xenografts has became a clinical requirement due to the problems related to source of donor tissue and the perceived risk of disease transmission. In the present study 3D tissue engineered construct of sericin is developed using co-culture of keratinocytes on the upper surface of the fabricated matrices and with fibroblasts on lower surface. Sericin is obtained from "Sericin Hope" silkworm of Bombyx mori mutant and is extracted from cocoons by autoclave. Porous sericin matrices are prepared by freeze dried method using genipin as crosslinker. The matrices are characterized biochemically and biophysically. The cell proliferation and viability of co-cultured fibroblasts and keratinocytes on matrices for at least 28 days are observed by live/dead assay, Alamar blue assay, and by dual fluorescent staining. The growth of the fibroblasts and keratinocytes in co-culture is correlated with the expression level of TGF-β, b-FGF and IL-8 in the cultured supernatants by enzyme-linked immunosorbent assay. The histological analysis further demonstrates a multi-layered stratified epidermal layer of uninhibited keratinocytes in co-cultured constructs. Presence of involucrin, collagen IV and the fibroblast surface protein in immuno-histochemical stained sections of co-cultured matrices indicates the significance of paracrine signaling between keratinocytes and fibroblasts in the expression of extracellular matrix protein for dermal repair. No significant amount of pro inflammatory cytokines (TNF-α, IL-1β and nitric oxide) production are evidenced when macrophages grown on the sericin matrices. The results all together depict the potentiality of sericin 3D matrices as skin equivalent tissue engineered construct in wound repair.
Waller, Niels G
2016-01-01
For a fixed set of standardized regression coefficients and a fixed coefficient of determination (R-squared), an infinite number of predictor correlation matrices will satisfy the implied quadratic form. I call such matrices fungible correlation matrices. In this article, I describe an algorithm for generating positive definite (PD), positive semidefinite (PSD), or indefinite (ID) fungible correlation matrices that have a random or fixed smallest eigenvalue. The underlying equations of this algorithm are reviewed from both algebraic and geometric perspectives. Two simulation studies illustrate that fungible correlation matrices can be profitably used in Monte Carlo research. The first study uses PD fungible correlation matrices to compare penalized regression algorithms. The second study uses ID fungible correlation matrices to compare matrix-smoothing algorithms. R code for generating fungible correlation matrices is presented in the supplemental materials.
O`Connor, P.
1994-09-01
This is a user`s manual for dBASE IV. dBASE IV is a popular software application that can be used on your personal computer to help organize and maintain your database files. It is actually a set of tools with which you can create, organize, select and manipulate data in a simple yet effective manner. dBASE IV offers three methods of working with the product: (1) control center: (2) command line; and (3) programming.
Dumais, M.M.; White, H.W.; Rashid, M.R.
1994-09-01
Detection of mutation, by SSCP or heteroduplex analysis, is important in medical genetics and oncology. Analysis of DNA binding proteins is a powerful tool in molecular biology research. Traditionally, these methods are performed using nondenaturing gel electrophoresis on poly-acrylamide or polyacrylamide-type matrices. Here we report the development of a new agarose gel matrix that can be used for all three methods. SSCP analyses were performed using the prototype agarose gel matrix for wild-type, polymorphic, and mutant samples from c-Kras exon 12, p53 exons 8 and 9, and HOX2B. We performed SSCP analyses using both isotopic and nonisotopic methods. We also analyzed the samples by deliberate HTX formation and subsequent gel analysis. Using the prototype agarose matrix, we detected single and multiple DNA sequence variants in 150-350 bp fragments with an efficiency comparable to polyacrylamide gels run under similar conditions. For SSCP and HTX assays, we achieved optimal resolution in gels run in vertical formats. However, some HTX samples could be resolved in horizontal gel systems. In addition, based on our studies, we have developed a useful battery of controls and standards for quality control of SSCP and HTX assays. We analyzed several different DNA/protein complexes (SP1, AP2, and octamer binding protein) using the prototype agarose matrix. We obtained good resolution in both vertical and horizontal gel formats. The horizontal gel system is generally superior for this application, due to its ease of use and slightly better resolution. This new prototype gel matrix offers an alternative for researchers performing analyses that previously could only be done on polyacrylamide-type gel matrices. For some applications, this new matrix offers the ease of horizontal gel casting. For all applications, this matrix offers the safety of a nontoxic system and the reproducibility of a thermally gelling system.
Approximate inverse preconditioners for general sparse matrices
Chow, E.; Saad, Y.
1994-12-31
Preconditioned Krylov subspace methods are often very efficient in solving sparse linear matrices that arise from the discretization of elliptic partial differential equations. However, for general sparse indifinite matrices, the usual ILU preconditioners fail, often because of the fact that the resulting factors L and U give rise to unstable forward and backward sweeps. In such cases, alternative preconditioners based on approximate inverses may be attractive. We are currently developing a number of such preconditioners based on iterating on each column to get the approximate inverse. For this approach to be efficient, the iteration must be done in sparse mode, i.e., we must use sparse-matrix by sparse-vector type operatoins. We will discuss a few options and compare their performance on standard problems from the Harwell-Boeing collection.
Edge universality for deformed Wigner matrices
NASA Astrophysics Data System (ADS)
Lee, Ji Oon; Schnelli, Kevin
2015-09-01
We consider N × N random matrices of the form H = W + V where W is a real symmetric Wigner matrix and V a random or deterministic, real, diagonal matrix whose entries are independent of W. We assume subexponential decay for the matrix entries of W and we choose V so that the eigenvalues of W and V are typically of the same order. For a large class of diagonal matrices V, we show that the rescaled distribution of the extremal eigenvalues is given by the Tracy-Widom distribution F1 in the limit of large N. Our proofs also apply to the complex Hermitian setting, i.e. when W is a complex Hermitian Wigner matrix.
Characteristic Matrices for Spherical Shell Photonic Systems
NASA Technical Reports Server (NTRS)
Fuller, Kirk A.; Smith, David D.
2004-01-01
We establish a parallel between the transfer matrix used in the study of plane-parallel photonic structures and the matrix characterizing transfer of partial waves in concentric spheres. We derive explicit expressions for the elements of the transfer matrix for concentric spherical layers, and from those expressions derive the scattering coefficients of a multilayered sphere. The transfer matrices are 4x4 block diagonal with only four independent elements. Matrix elements for the case of TM waves are related to those for the case of TE waves through simple interchange and multiplicative constants. In analogy with plane parallel layers, the transfer matrix for concentric multilayers is simply the product of the transfer matrices of the individual layers.
Evolutionary Games with Randomly Changing Payoff Matrices
NASA Astrophysics Data System (ADS)
Yakushkina, Tatiana; Saakian, David B.; Bratus, Alexander; Hu, Chin-Kun
2015-06-01
Evolutionary games are used in various fields stretching from economics to biology. In most of these games a constant payoff matrix is assumed, although some works also consider dynamic payoff matrices. In this article we assume a possibility of switching the system between two regimes with different sets of payoff matrices. Potentially such a model can qualitatively describe the development of bacterial or cancer cells with a mutator gene present. A finite population evolutionary game is studied. The model describes the simplest version of annealed disorder in the payoff matrix and is exactly solvable at the large population limit. We analyze the dynamics of the model, and derive the equations for both the maximum and the variance of the distribution using the Hamilton-Jacobi equation formalism.
Confirmatory Factor Analysis of the WAIS-IV/WMS-IV
ERIC Educational Resources Information Center
Holdnack, James A.; Zhou, Xiaobin; Larrabee, Glenn J.; Millis, Scott R.; Salthouse, Timothy A.
2011-01-01
The Wechsler Adult Intelligence Scale-fourth edition (WAIS-IV) and the Wechsler Memory Scale-fourth edition (WMS-IV) were co-developed to be used individually or as a combined battery of tests. The independent factor structure of each of the tests has been identified; however, the combined factor structure has yet to be determined. Confirmatory…
Improving IV-A/IV-D Interface. Trainer Guide.
ERIC Educational Resources Information Center
National Inst. for Child Support Enforcement, Chevy Chase, MD.
Effective interface between the Aid to Families with Dependent Children (IV-A) and the Child Support Enforcement (IV-D) programs is a key factor in assisting families in becoming self-sufficient, reducing welfare expenditures, and enforcing parental responsibility to support their children. Consequently, overcoming the procedural, technological,…
Improving IV-A/IV-D Interface. Handbook.
ERIC Educational Resources Information Center
National Inst. for Child Support Enforcement, Chevy Chase, MD.
Effective interface between the Aid to Families with Dependent Children (IV-A) and the Child Support Enforcement (IV-D) programs is a key factor in assisting families in becoming self-sufficient, reducing welfare expenditures, and enforcing parental responsibility to support their children. Consequently, overcoming the procedural, technological,…
Analysis of thematic map classification error matrices.
Rosenfield, G.H.
1986-01-01
The classification error matrix expresses the counts of agreement and disagreement between the classified categories and their verification. Thematic mapping experiments compare variables such as multiple photointerpretation or scales of mapping, and produce one or more classification error matrices. This paper presents a tutorial to implement a typical problem of a remotely sensed data experiment for solution by the linear model method.-from Author
Some physical applications of random hierarchical matrices
Avetisov, V. A.; Bikulov, A. Kh.; Vasilyev, O. A.; Nechaev, S. K.; Chertovich, A. V.
2009-09-15
The investigation of spectral properties of random block-hierarchical matrices as applied to dynamic and structural characteristics of complex hierarchical systems with disorder is proposed for the first time. Peculiarities of dynamics on random ultrametric energy landscapes are discussed and the statistical properties of scale-free and polyscale (depending on the topological characteristics under investigation) random hierarchical networks (graphs) obtained by multiple mapping are considered.
Computing partial traces and reduced density matrices
NASA Astrophysics Data System (ADS)
Maziero, Jonas
Taking partial traces (PTrs) for computing reduced density matrices, or related functions, is a ubiquitous procedure in the quantum mechanics of composite systems. In this paper, we present a thorough description of this function and analyze the number of elementary operations (ops) needed, under some possible alternative implementations, to compute it on a classical computer. As we note, it is worthwhile doing some analytical developments in order to avoid making null multiplications and sums, what can considerably reduce the ops. For instance, for a bipartite system ℋa⊗ℋb with dimensions da=dimℋa and db=dimℋb and for da,db≫1, while a direct use of PTr definition applied to ℋb requires 𝒪(da6db6) ops, its optimized implementation entails 𝒪(da2db) ops. In the sequence, we regard the computation of PTrs for general multipartite systems and describe Fortran code provided to implement it numerically. We also consider the calculation of reduced density matrices via Bloch’s parametrization with generalized Gell Mann’s matrices.
Scattering Matrices and Conductances of Leaky Tori
NASA Astrophysics Data System (ADS)
Pnueli, A.
1994-04-01
Leaky tori are two-dimensional surfaces that extend to infinity but which have finite area. It is a tempting idea to regard them as models of mesoscopic systems connected to very long leads. Because of this analogy-scattering matrices on leaky tori are potentially interesting, and indeed-the scattering matrix on one such object-"the" leaky torus-was studied by M. Gutzwiller, who showed that it has chaotic behavior. M. Antoine, A. Comtet and S. Ouvry generalized Gutzwiller‧s result by calculating the scattering matrix in the presence of a constant magnetic field B perpendicular to the surface. Motivated by these results-we generalize them further. We define scattering matrices for spinless electrons on a general leaky torus in the presence of a constant magnetic field "perpendicular" to the surface. From the properties of these matrices we show the following: (a) For integer values of B, Tij (the transition probability from cusp i to cusp j), and hence also the Büttiker conductances of the surfaces, are B-independent (this cannot be interpreted as a kind of Aharonov-Bohm effect since a magnetic force is acting on the electrons). (b) The Wigner time-delay is a monotonically increasing function of B.
Preconditioning matrices for Chebyshev derivative operators
NASA Technical Reports Server (NTRS)
Rothman, Ernest E.
1986-01-01
The problem of preconditioning the matrices arising from pseudo-spectral Chebyshev approximations of first order operators is considered in both one and two dimensions. In one dimension a preconditioner represented by a full matrix which leads to preconditioned eigenvalues that are real, positive, and lie between 1 and pi/2, is already available. Since there are cases in which it is not computationally convenient to work with such a preconditioner, a large number of preconditioners were studied which were more sparse (in particular three and four diagonal matrices). The eigenvalues of such preconditioned matrices are compared. The results were applied to the problem of finding the steady state solution to an equation of the type u sub t = u sub x + f, where the Chebyshev collocation is used for the spatial variable and time discretization is performed by the Richardson method. In two dimensions different preconditioners are proposed for the matrix which arises from the pseudo-spectral discretization of the steady state problem. Results are given for the CPU time and the number of iterations using a Richardson iteration method for the unpreconditioned and preconditioned cases.
[A study on the formation of apatite crystallized with gel method].
Endo, T; Amano, N; Yoshida, M; Murakami, H; Kosuge, N; Ohmi, Y; Kameda, A
1989-10-01
About apatite produced with a silicahydro gel method using calcium nitrate (group I) or calcium chloride (group II) and a gelatin gel method by use of calcium nitrate (group III) or calcium chloride (group IV), the formative volume as well as the formative condition of a periodic-layered precipitate (Liesegang ring), the pH measurement, calculation of Ca/P ratio, an estimation of the chlorine ion, morphological observation with a scanning electron microscope, qualitative analyses by X-ray diffraction (identification, crystallite size, lattice imperfections, lattice constants) and the composition analysis by infrared absorption spectroscopy were carried out to elucidate the formation of apatite using the gel method. The result showed that there were no distinct differences between group I-II and group III-IV, and it is suggested that it is possible to form satisfact fluorapatite with a gel method using calcium chloride as well as calcium nitrate.
Deterministic sensing matrices in compressive sensing: a survey.
Nguyen, Thu L N; Shin, Yoan
2013-01-01
Compressive sensing is a sampling method which provides a new approach to efficient signal compression and recovery by exploiting the fact that a sparse signal can be suitably reconstructed from very few measurements. One of the most concerns in compressive sensing is the construction of the sensing matrices. While random sensing matrices have been widely studied, only a few deterministic sensing matrices have been considered. These matrices are highly desirable on structure which allows fast implementation with reduced storage requirements. In this paper, a survey of deterministic sensing matrices for compressive sensing is presented. We introduce a basic problem in compressive sensing and some disadvantage of the random sensing matrices. Some recent results on construction of the deterministic sensing matrices are discussed.
NATIONAL COASTAL CONDITION REPORT IV
The National Coastal Condition Report IV (NCCR IV) is the fourth in a series of environmental assessments of U.S. coastal waters and the Great Lakes. The report includes assessments of all the nation’s estuaries in the contiguous 48 states and Puerto Rico, south-eastern Alaska, ...
Nanoscale Motion of Soft Nanoparticles in Unentangled and Entangled Polymer Matrices
NASA Astrophysics Data System (ADS)
Lungova, M.; Krutyeva, M.; Pyckhout-Hintzen, W.; Wischnewski, A.; Monkenbusch, M.; Allgaier, J.; Ohl, M.; Sharp, M.; Richter, D.
2016-09-01
We have studied the motion of polyhedral oligomeric silsesquioxane (POSS) nanoparticles modified with poly(ethylene glycol) (PEG) arms immersed in PEG matrices of different molecular weight. Employing neutron spin echo spectroscopy in combination with pulsed field gradient (PFG) NMR we found the following. (i) For entangled matrices the center of mass mean square displacement (MSD) of the PEG-POSS particles is subdiffusive following a t0.56 power law. (ii) The diffusion coefficient as well as the crossover to Fickian diffusion is independent of the matrix molecular weight and takes place as soon as the center of mass has moved a distance corresponding to the particle radius—this holds also for unentangled hosts. (iii) For the entangled matrices Rubinstein's scaling theory is validated; however, the numbers indicate that beyond Rouse friction the entanglement constraints appear to strongly increase the effective friction even on the nanoparticle length scale imposing a caveat on the interpretation of microrheological experiments. (iv) The oligomer decorated PEG-POSS particles exhibit the dynamics of a Gaussian star with an internal viscosity that rises with an increase of the host molecular weight.
Flavonoids as matrices for MALDI-TOF mass spectrometric analysis of transition metal complexes
NASA Astrophysics Data System (ADS)
Petkovic, Marijana; Petrovic, Biljana; Savic, Jasmina; Bugarcic, Zivadin D.; Dimitric-Markovic, Jasmina; Momic, Tatjana; Vasic, Vesna
2010-02-01
Matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a suitable method for the analysis of inorganic and organic compounds and biomolecules. This makes MALDI-TOF MS convenient for monitoring the interaction of metallo-drugs with biomolecules. Results presented in this manuscript demonstrate that flavonoids such as apigenin, kaempferol and luteolin are suitable for MALDI-TOF MS analysis of Pt(II), Pd(II), Pt(IV) and Ru(III) complexes, giving different signal-to-noise ratios of the analyte peak. The MALDI-TOF mass spectra of inorganic complexes acquired with these flavonoid matrices are easy to interpret and have some advantages over the application of other commonly used matrices: a low number of matrix peaks are detectable and the coordinative metal-ligand bond is, in most cases, preserved. On the other hand, flavonoids do not act as typical matrices, as their excess is not required for the acquisition of MALDI-TOF mass spectra of inorganic complexes.
NASA Astrophysics Data System (ADS)
Abdikalykov, A. K.
2015-05-01
The following problem is discussed: what are unitary n × n matrices U that map the linear space of ( T + H)-matrices into itself by similarity transformations? Analogous problems for the spaces of Toeplitz and Hankel matrices were solved recently. For ( T + H)-matrices, the problem of describing appropriate matrices U appears to be considerably more complex and is still open. The result proved in this paper may contribute to the complete solution of this problem. Namely, every such matrix U is either centrosymmetric or skew-centrosymmetric; moreover, only the first variant is possible for odd n.
Intestinal apolipoprotein A-IV gene expression in the piglet.
Black, D D; Rohwer-Nutter, P L; Davidson, N O
1990-03-01
Fetal, newborn, and suckling piglets were used to study the intestinal expression of the apoA-IV gene in the immature mammal. Swine apoA-IV (42 kD) was isolated from fat-fed piglet lipoprotein-deficient plasma by adsorption to Intralipid followed by preparative sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and electroelution. Rabbit anti-swine apoA-IV antibodies were raised, and apoA-IV was immunoprecipitated from small intestinal homogenates after in vivo radiolabeling with [3H]leucine. ApoA-IV synthesis was expressed as a percentage of total protein synthesis from trichloroacetic acid-precipitable counts. Fetal (40 day gestation) whole small intestine synthesis was 2.1%. Postnatally, 2-day-old newborn piglets given high triglyceride and low triglyceride duodenal infusions, as well as bile diversion, were studied. Synthesis rates in jejunal mucosa in all groups were comparable to the fetal whole intestinal value except in the jejunum of the high-triglyceride group, where synthesis was increased sevenfold. In 1- to 2-week-old fasting, cream-fed, and bile-diverted piglets synthesis was again unchanged except in the fat-fed jejunum, where synthesis doubled. Ileal synthesis rates in newborn and suckling animals were lower than jejunal rates and did not increase with lipid absorption or decrease with bile diversion. Northern blot hybridization of intestinal RNA samples from the newborn groups with an authentic cross-hybridizing human apoA-IV cDNA probe revealed a 1.8 kb signal which was strongest in the high-triglyceride jejunal samples. Slot blot hybridization showed eightfold increased apoA-IV mRNA levels in high-triglyceride jejunal samples as compared to low-triglyceride and bile-diverted jejunum with no differences in beta actin mRNA abundance.(ABSTRACT TRUNCATED AT 250 WORDS)
DeVolder, Ross J.; Kim, Il Won; Kim, Eun-Suk
2012-01-01
Extensive efforts have been made to prepare osteoconductive collagen gels for the regeneration of normal bone and the pathological examination of diseased bone; however, collagen gels are often plagued by limited controllability of their rigidity and mineral deposition. This study reports a simple but efficient strategy that tunes the mechanical properties of, and apatite formation in, collagen gels by incorporating hydrolyzable poly(lactic-co-glycolic acid) (PLGA) microparticles within the gels. The PLGA microparticles are associated with the collagen fibrils and increased both the gel's elasticity and rigidity while minimally influencing its permeability. As compared with pure collagen gels, the PLGA microparticle-filled collagen gels, termed PLGA-Col hydrogels, significantly enhanced the deposition of apatite-like minerals within the gels when incubated in simulated body fluid or encapsulated with mesenchymal stem cells (MSCs) undergoing osteogenic differentiation. Finally, PLGA-Col hydrogels mineralized by differentiated MSCs led to an enhanced formation of bone-like tissues within the hydrogels. Overall, the PLGA-Col hydrogel system developed in this study will serve to improve the quality of osteoconductive matrices for both fundamental and clinical studies that are relevant to bone repair, regeneration, and pathogenesis. PMID:22480235
Taru Sharma, G.; Dubey, Pawan K.; Verma, Om Prakash; Pratheesh, M.D.; Nath, Amar; Sai Kumar, G.
2012-08-03
Graphical abstract: EBs formation, characterization and expression of germinal layers marker genes of in vivo developed teratoma using four different types of extracellular matrices. Highlights: Black-Right-Pointing-Pointer Collagen-IV matrix is found cytocompatible for EBs formation and differentiation. Black-Right-Pointing-Pointer Established 3D microenvironment for ES cells development and differentiation into three germ layers. Black-Right-Pointing-Pointer Collagen-IV may be useful as promising candidate for ES cells based therapeutic applications. -- Abstract: Embryoid bodies (EBs) are used as in vitro model to study early extraembryonic tissue formation and differentiation. In this study, a novel method using three dimensional extracellular matrices for in vitro generation of EBs from buffalo embryonic stem (ES) cells and its differentiation potential by teratoma formation was successfully established. In vitro derived inner cell masses (ICMs) of hatched buffalo blastocyst were cultured on buffalo fetal fibroblast feeder layer for primary cell colony formation. For generation of EBs, pluripotent ES cells were seeded onto four different types of extracellular matrices viz; collagen-IV, laminin, fibronectin and matrigel using undifferentiating ES cell culture medium. After 5 days of culture, ESCs gradually grew into aggregates and formed simple EBs having circular structures. Twenty-six days later, they formed cystic EBs over collagen matrix with higher EBs formation and greater proliferation rate as compared to other extracellular matrices. Studies involving histological observations, fluorescence microscopy and RT-PCR analysis of the in vivo developed teratoma revealed that presence of all the three germ layer derivatives viz. ectoderm (NCAM), mesoderm (Flk-1) and endoderm (AFP). In conclusion, the method described here demonstrates a simple and cost-effective way of generating EBs from buffalo ES cells. Collagen-IV matrix was found cytocompatible as it
NASA Astrophysics Data System (ADS)
Hou, Lisong; Mennig, Martin; Schmidt, Helmut K.
1994-09-01
The sol-gel method which features a low-temperature wet-chemical process opens vast possibilities to incorporating organic dyes into solid matrices for various optical applications. In this paper we present our experimental results on the sol-gel derived photochromic organic- inorganic composite (Ormocer) materials following an introductory description of the sol-gel process and a brief review on the state of the art of the photochromic solids prepared using this method. Our photochromic spirooxazine-Ormocer gels and coatings possess better photochromic response and color-change speed than the corresponding photochromic polymer coatings and similar photochemical stability to the latter. Further developments are proposed as to tackle the temperature dependence problem and further tap the potentialities of the photochromic dye-Ormocer material for practical applications.
NASA Astrophysics Data System (ADS)
Cargo, Patricia; Gallice, Gérard
1997-09-01
In this paper, the construction of a Roe's scheme for the conservative system of ideal magnetohydrodynamics (MHD) is presented. As this method relies on the computation of a Roe matrix, the problem is to find a matrixA(Ul,Ur) which satisfies the following properties. It is required to be consistent with the jacobian of the fluxF, to have real eigenvalues, a complete set of eigenvectors and to satisfy the relation: ΔF=A(Ul,Ur) ΔU, whereUlandUrare two admissible states and ΔUtheir difference. For the ideal MHD system, using eulerian coordinates, a Roe matrix is obtained without any hypothesis on the specific heat ratio. Especially, its construction relies on an original expression of the magnetic pressure jump. Moreover, a Roe matrix is computed for lagrangian ideal MHD, by extending the results of Munz who obtained such a matrix for the system of lagrangian gas dynamics. So this second matrix involves arithmetic averages unlike the eulerian one, which contains classical Roe averages like in eulerian gas dynamics. In this paper, a systematic construction of lagrangian Roe matrices in terms of eulerian Roe matrices for a general system of conservation laws is also presented. This result, applied to the above eulerian and lagrangian matrices for ideal MHD, gives two new matrices for this system. In the same way, by applying this construction to the gas dynamics equations new Roe matrices are also obtained. All these matrices allow the construction of Roe type schemes. Some numerical examples on the shock tube problem show the applicability of this method.
Novel hybrid sol-gel materials for smart sensor windows
NASA Astrophysics Data System (ADS)
Wencel, Dorota; Higgins, Clare; Guckian, Adrian; McDonagh, Colette; MacCraith, Brian D.
2005-06-01
Current sensor trends, such as multianalyte capability, miniaturisation and patternability are important drivers for materials requirements in optical chemical sensors. In particular, issues such as enhanced sensitivity and printablity are key in developing optimised sensor materials for smart windows for bioprocessing applications. This study focuses on combining novel sol-gel-based hybrid matrices with engineered luminescent complexes to produce stable luminescence-based optical sensors with enhanced sensitivity for a range of analytes including oxygen, pH and carbon dioxide. As well as optimising sensor performance, issues such as surface modification of the plastic substrate and compatibility with different deposition techniques were addressed. Hybrid sol-gel matrices were developed using a range of precursors including tetraethoxysilane (TEOS), methyltriethoxysilane (MTEOS), ethyltriethoxysilane (ETEOS), n-propyltriethoxysilane (PTEOS), phenyltriethoxysilane (PhTEOS), and n-octyltriethoxysilane (C8TEOS). Oxygen sensing, based on luminescence quenching of ruthenium phenanthroline complexes, has been realised with each of these hybrid materials. Furthermore, the possibility of immobilising pH-indicators for pH and carbon dioxide sensing has been investigated with some success. In the context of in-situ monitoring of bioprocesses, issues such as humidity interference as well as the chemical robustness of the multianalyte platform, were addressed.
Brown, M Alex; Paulenova, Alena; Gelis, Artem V
2012-07-16
Aqueous complexation of Th(IV), U(IV), Np(IV), Pu(III/IV), and Ce(III/IV) with DTPA was studied by potentiometry, absorption spectrophotometry, and cyclic voltammetry at 1 M ionic strength and 25 °C. The stability constants for the 1:1 complex of each trivalent and tetravalent metal were calculated. From the potentiometric data, we report stability constant values for Ce(III)DTPA, Ce(III)HDTPA, and Th(IV)DTPA of log β(101) = 20.01 ± 0.02, log β(111) = 22.0 ± 0.2, and log β(101) = 29.6 ± 1, respectively. From the absorption spectrophotometry data, we report stability constant values for U(IV)DTPA, Np(IV)DTPA, and Pu(IV)DTPA of log β(101) = 31.8 ± 0.1, 32.3 ± 0.1, and 33.67 ± 0.02, respectively. From the cyclic voltammetry data, we report stability constant values for Ce(IV) and Pu(III) of log β(101) = 34.04 ± 0.04 and 20.58 ± 0.04, respectively. The values obtained in this work are compared and discussed with respect to the ionic radius of each cationic metal.
Identifying complexity by means of matrices
NASA Astrophysics Data System (ADS)
Drożdż, S.; Kwapień, J.; Speth, J.; Wójcik, M.
2002-11-01
Complexity is an interdisciplinary concept which, first of all, addresses the question of how order emerges out of randomness. For many reasons matrices provide a very practical and powerful tool in approaching and quantifying the related characteristics. Based on several natural complex dynamical systems, like the strongly interacting quantum many-body systems, the human brain and the financial markets, by relating empirical observations to the random matrix theory and quantifying deviations in terms of a reduced dimensionality, we present arguments in favour of the statement that complexity is a phenomenon at the edge between collectivity and chaos.
Parallel mergs sort using comparison matrices. I
Romm, Y.E.
1995-05-01
The topics discussed in this paper are connected with internal merge sorting by a key (in short, M-sorting or M-sort). Originally developed by von Neumann, this is one of the first sorting methods. It still remains one of the fastest, involving Nlog{sub 2}N comparisons. The purpose of our article is to demonstrate the use of comparison matrices (CMs) for merging in M-sort. While preserving the known advantages of the sequential implementation of M-sort. CMs ensure more efficient use of main memory (one of the known weaknesses of M-sort is its large memory requirements) and effective parallelizability.
Asymptotic properties of infinite Leslie matrices.
Gosselin, Frédéric; Lebreton, Jean-Dominique
2009-01-21
The stable population theory is classically applicable to populations in which there is a maximum age after which individuals die. Demetrius [1972. On an infinite population matrix. Math. Biosci. 13, 133-137] extended this theory to infinite Leslie matrices, in which the longevity of individuals is potentially infinite. However, Demetrius had to assume that the survival probability per time step tends to 0 with age. We generalise here the conditions of application of the stable population theory to infinite Leslie matrix models and apply these results to two examples, including or not senescence.
Apparatus and method for the production of gel beads containing a biocatalyst
Scott, Charles D.; Scott, Timothy C.; Davison, Brian H.
1998-01-01
An apparatus and method for the large-scale and continuous production of gel beads containing a biocatalyst. The apparatus is a columnar system based on the chemical cross-linking of hydrocolloidal gels that contain and immobilize a biocatalyst, the biocatalyst being a microorganism or an enzyme. Hydrocolloidal gels, such as alginate, carrageenan, and a mixture of bone gelatin and modified alginate, provide immobilization matrices that can be used to entrap and retain the biocatalyst while allowing effective contact with substrates and release of products. Such immobilized biocatalysts are generally formulated into small spheres or beads that have high concentrations of the biocatalyst within the gel matrix. The columnar system includes a gel dispersion nozzle submerged in a heated non-interacting liquid, typically an organic liquid, that is immiscible with water to allow efficient formation of spherical gel droplets, the non-interacting liquid having a specific gravity that is less than water so that the gel droplets will fall through the liquid by the force of gravity. The heated non-interacting liquid is in direct contact with a chilled upflowing non-interacting liquid that will provide sufficient residence time for the gel droplets as they fall through the liquid so that they will be cooled below the gelling temperature and form solid spheres. The upflowing non-interacting liquid is in direct contact with an upflowing temperature-controlled aqueous solution containing the necessary chemicals for cross-linking or fixing of the gel beads to add the necessary stability. The flow rates of the two liquid streams can be varied to control the proper residence time in each liquid section to accommodate the production of gel beads of differing settling velocities. A valve is provided for continuous removal of the stabilized gel beads from the bottom of the column.
Apparatus and method for the production of gel beads containing a biocatalyst
Scott, C.D.; Scott, T.C.; Davison, B.H.
1998-01-27
An apparatus and method are disclosed for the large-scale and continuous production of gel beads containing a biocatalyst. The apparatus is a columnar system based on the chemical cross-linking of hydrocolloidal gels that contain and immobilize a biocatalyst, the biocatalyst being a microorganism or an enzyme. Hydrocolloidal gels, such as alginate, carrageenan, and a mixture of bone gelatin and modified alginate, provide immobilization matrices that can be used to entrap and retain the biocatalyst while allowing effective contact with substrates and release of products. Such immobilized biocatalysts are generally formulated into small spheres or beads that have high concentrations of the biocatalyst within the gel matrix. The columnar system includes a gel dispersion nozzle submerged in a heated non-interacting liquid, typically an organic liquid, that is immiscible with water to allow efficient formation of spherical gel droplets, the non-interacting liquid having a specific gravity that is less than water so that the gel droplets will fall through the liquid by the force of gravity. The heated non-interacting liquid is in direct contact with a chilled upflowing non-interacting liquid that will provide sufficient residence time for the gel droplets as they fall through the liquid so that they will be cooled below the gelling temperature and form solid spheres. The upflowing non-interacting liquid is in direct contact with an upflowing temperature-controlled aqueous solution containing the necessary chemicals for cross-linking or fixing of the gel beads to add the necessary stability. The flow rates of the two liquid streams can be varied to control the proper residence time in each liquid section to accommodate the production of gel beads of differing settling velocities. A valve is provided for continuous removal of the stabilized gel beads from the bottom of the column. 1 fig.
Tielmann, Patrick; Kierkels, Hans; Zonta, Albin; Ilie, Adriana; Reetz, Manfred T
2014-06-21
The entrapment of lipases in hydrophobic silicate matrices formed by sol-gel mediated hydrolysis of RSi(OCH3)3/Si(OCH3)4 as originally reported in 1996 has been improved over the years by a number of modifications. In the production of second-generation sol-gel lipase immobilizates, a variety of additives during the sol-gel process leads to increased activity and enhanced stereoselectivity in esterifying kinetic resolution. Recent advances in this type of lipase immobilization are reviewed here, in addition to new results regarding the sol-gel entrapment of the lipase from Burkholderia cepacia. It constitutes an excellent heterogeneous biocatalyst in the acylating kinetic resolution of two synthetically and industrially important chiral alcohols, rac-sulcatol and rac-trans-2-methoxycyclohexanol. The observation that the catalyst can be used 10 times in recycling experiments without losing its significant activity or enantioselectivity demonstrates the practical viability of the sol-gel approach.
Wagner, C.
1996-12-31
In 1992, Wittum introduced the frequency filtering decompositions (FFD), which yield a fast method for the iterative solution of large systems of linear equations. Based on this method, the tangential frequency filtering decompositions (TFFD) have been developed. The TFFD allow the robust and efficient treatment of matrices with strongly varying coefficients. The existence and the convergence of the TFFD can be shown for symmetric and positive definite matrices. For a large class of matrices, it is possible to prove that the convergence rate of the TFFD and of the FFD is independent of the number of unknowns. For both methods, schemes for the construction of frequency filtering decompositions for unsymmetric matrices have been developed. Since, in contrast to Wittums`s FFD, the TFFD needs only one test vector, an adaptive test vector can be used. The TFFD with respect to the adaptive test vector can be combined with other iterative methods, e.g. multi-grid methods, in order to improve the robustness of these methods. The frequency filtering decompositions have been successfully applied to the problem of the decontamination of a heterogeneous porous medium by flushing.
Bromination of selected pharmaceuticals in water matrices.
Benitez, F Javier; Acero, Juan L; Real, Francisco J; Roldan, Gloria; Casas, Francisco
2011-11-01
The bromination of five selected pharmaceuticals (metoprolol, naproxen, amoxicillin, phenacetin, and hydrochlorothiazide) was studied with these compounds individually dissolved in ultra-pure water. The apparent rate constants for the bromination reaction were determined as a function of the pH, obtaining the sequence amoxicillin>naproxen>hydrochlorothiazide≈phenacetin≈metoprolol. A kinetic mechanism specifying the dissociation reactions and the species formed for each compound according to its pK(a) value and the pH allowed the intrinsic rate constants to be determined for each elementary reaction. There was fairly good agreement between the experimental and calculated values of the apparent rate constants, confirming the goodness of the proposed reaction mechanism. In a second stage, the bromination of the selected pharmaceuticals simultaneously dissolved in three water matrices (a groundwater, a surface water from a public reservoir, and a secondary effluent from a WWTP) was investigated. The pharmaceutical elimination trend agreed with the previously determined rate constants. The influence of the main operating conditions (pH, initial bromine dose, and characteristics of the water matrix) on the degradation of the pharmaceuticals was established. An elimination concentration profile for each pharmaceutical in the water matrices was proposed based on the use of the previously evaluated apparent rate constants, and the theoretical results agreed satisfactorily with experiment. Finally, chlorination experiments performed in the presence of bromide showed that low bromide concentrations slightly accelerate the oxidation of the selected pharmaceuticals during chlorine disinfection.
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.
Solid-state active media on the base of silica matrices doped with UV and visible laser dyes
NASA Astrophysics Data System (ADS)
Kuznetsova, R. T.; Manekina, Ju. A.; Telminov, E. N.; Mayer, G. V.; Arabei, S. M.; Pavich, T. A.; Solovyov, K. N.
2007-06-01
New results on the influence of the composition of a silica gel-matrix and the process of its production on the spectral, lasing and photochemical properties of embedded luminophores: rhodamine, phenalemine, oxazole, coumarine and other dyes series, which have lasing in the UV, blue-green and red spectral regions under excitation by poweful laser radiation of various wavelength (308 and 532 nm) and intensity (from 0,1 to 100 MW/cm2) have been obtained. The shortest-wavelength lasing is achieved for silica solid matrices with para-terphenyl (342 nm). Optimal conditions have been selected and the lasing of thin silica solid films doped with aminocoumarine (457 nm) with resource exceeding that in solutions has been obtained. It is established, that organic luminophores are fixed in nanodimensional pores of silica and hybrid matrices by specific interactions, that compete with the association of dyes.
Electrically controlled polymeric gel actuators
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.
Electrically controlled polymeric gel actuators
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.
Gel polymer electrolytes for batteries
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.
Generating correlation matrices based on the boundaries of their coefficients.
Numpacharoen, Kawee; Atsawarungruangkit, Amporn
2012-01-01
Correlation coefficients among multiple variables are commonly described in the form of matrices. Applications of such correlation matrices can be found in many fields, such as finance, engineering, statistics, and medicine. This article proposes an efficient way to sequentially obtain the theoretical bounds of correlation coefficients together with an algorithm to generate n × n correlation matrices using any bounded random variables. Interestingly, the correlation matrices generated by this method using uniform random variables as an example produce more extreme relationships among the variables than other methods, which might be useful for modeling complex biological systems where rare cases are very important.
A multiple shift QR-step for structured rank matrices
NASA Astrophysics Data System (ADS)
Vandebril, Raf; van Barel, Marc; Mastronardi, Nicola
2010-01-01
Eigenvalue computations for structured rank matrices are the subject of many investigations nowadays. There exist methods for transforming matrices into structured rank form, QR-algorithms for semiseparable and semiseparable plus diagonal form, methods for reducing structured rank matrices efficiently to Hessenberg form and so forth. Eigenvalue computations for the symmetric case, involving semiseparable and semiseparable plus diagonal matrices have been thoroughly explored. A first attempt for computing the eigenvalues of nonsymmetric matrices via intermediate Hessenberg-like matrices (i.e. a matrix having all subblocks in the lower triangular part of rank at most one) was restricted to the single shift strategy. Unfortunately this leads in general to the use of complex shifts switching thereby from real to complex operations. This paper will explain a general multishift implementation for Hessenberg-like matrices (semiseparable matrices are a special case and hence also admit this approach). Besides a general multishift QR-step, this will also admit restriction to real computations when computing the eigenvalues of arbitrary real matrices. Details on the implementation are provided as well as numerical experiments proving the viability of the presented approach.
Wang, Jian; Ugaz, Victor M
2006-09-01
Photopolymerized cross-linked polyacrylamide hydrogels are attractive sieving matrix formulations for DNA electrophoresis owing to their rapid polymerization times and the potential to locally tailor the gel pore structure through spatial variation of illumination intensity. This capability is especially important in microfluidic systems, where photopolymerization allows gel matrices to be precisely positioned within complex microchannel networks. Separation performance is also directly related to the nanoscale gel pore structure, which is in turn strongly influenced by polymerization kinetics. Unfortunately, detailed studies of the interplay among polymerization kinetics, mechanical properties, and structural morphology are lacking in photopolymerized hydrogel systems. In this paper, we address this issue by performing a series of in situ dynamic small-amplitude oscillatory shear measurements during photopolymerization of cross-linked polyacrylamide electrophoresis gels to investigate the relationship between rheology and parameters associated with the gelation environment including UV intensity, monomer and cross-linker composition, and reaction temperature. In general, we find that the storage modulus G' increases with increasing initial monomer concentration, cross-linker concentration, and polymerization temperature. The steady-state value of G', however, exhibits a more complex dependence on UV intensity that varies with gel concentration. A simple model based on rubber elasticity theory is used to obtain estimates of the average gel pore size that are in surprisingly good agreement with corresponding data obtained from analysis of DNA electrophoretic mobility in gels cast under identical polymerization conditions.
Louie, Andrew J.; Dixon, Gordon H.
1972-01-01
During spermatogenesis in trout testis, histone IV is extensively modified by acetylation and phosphorylation. To examine the relationship of synthesis of histone IV to its modification, histone IV labeled with [3H]aminoacids and inorganic [32P]phosphate was prepared from testis cells by acid extraction and column chromatography. Purified histone IV was resolved by starch gel electrophoresis into 10 bands, of which nine are modified by acetylation and/or phosphorylation. In the first 4 hr of labeling, the diacetyl-histone IV band showed the highest proportion of [3H]aminoacid label. After 12 hr of incorporation, more label was found in the triacetyl and tetraacetyl bands. A significant amount of amino-acid label in the two major bands (the unsubstituted and monoacetyl bands) of histone IV was not seen until 16 hr of incubation. From 1 to 12 days, the proportion of label in the unsubstituted and monoacetylated bands increased, while that in the tetra-, tri-, and monoacetyl bands decreased. Very little [3H]aminoacid was found in the phosphorylated bands of histone IV in the first 12 hr. However, after 16 hr about 20% of the total 3H was found in the phosphorylated bands. The proportion increased to 33% and remained at this level between 1 and 8 days, but, by 16 days, had decreased to 12% of the total. These data suggest that an “obligatory” acetylation of recently synthesized histone IV is involved in the correct binding of newly synthesized histone IV to DNA. We propose that ε-amino acetylation of lysyl residues 5, 8, 12, and 16 neutralizes their positive charges and allows the NH2-terminal region of histone IV to assume the correct conformation (in this case, an α-helix), and fit into the major groove of DNA. Deacetylation then “locks” histone IV to DNA by ionic linkages. The biological significance of phosphorylation of histone IV is not known. Images PMID:4505675
Thermogelling polymer-platinum(IV) conjugates for long-term delivery of cisplatin.
Shen, Wenjia; Luan, Jiabin; Cao, Luping; Sun, Jian; Yu, Lin; Ding, Jiandong
2015-01-12
In this study, we suggest a novel strategy of constituting an in situ-formed hydrogel composed of polymer-platinum(IV) conjugate to realize a long-term delivery of cisplatin. A unique conjugate was designed and synthesized by covalent linking of Pt(IV) complex to the hydrophobic end of two methoxyl poly(ethylene glycol)-b-poly(d,l-lactide) (mPEG-PLA) copolymer chains, resulting in the formation of Bi(mPEG-PLA)-Pt(IV). The conjugate could self-assemble into micelles in water, and its concentrated solution exhibited a thermoreversible sol-gel transition and formed a semisolid thermogel at body temperature. The incorporation of the cisplatin analogue Pt(IV) prodrug into the conjugate had a significant influence on its thermogelling properties and the conjugate thermogelation was attributed to the micellar aggregation. In vitro release experiments of Pt(IV)-conjugated thermogel showed that the platinum release lasted as long as two months. Furthermore, we demonstrated that the Pt(IV) prodrug was released mainly in the form of micelles and micellar aggregates from the gel depot. Compared with free cisplatin, the formation of conjugate micelles led to the enhanced in vitro cytotoxicity against cancer cells due to the effective accumulation into cells via endocytosis.
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.
Noisy covariance matrices and portfolio optimization II
NASA Astrophysics Data System (ADS)
Pafka, Szilárd; Kondor, Imre
2003-03-01
Recent studies inspired by results from random matrix theory (Galluccio et al.: Physica A 259 (1998) 449; Laloux et al.: Phys. Rev. Lett. 83 (1999) 1467; Risk 12 (3) (1999) 69; Plerou et al.: Phys. Rev. Lett. 83 (1999) 1471) found that covariance matrices determined from empirical financial time series appear to contain such a high amount of noise that their structure can essentially be regarded as random. This seems, however, to be in contradiction with the fundamental role played by covariance matrices in finance, which constitute the pillars of modern investment theory and have also gained industry-wide applications in risk management. Our paper is an attempt to resolve this embarrassing paradox. The key observation is that the effect of noise strongly depends on the ratio r= n/ T, where n is the size of the portfolio and T the length of the available time series. On the basis of numerical experiments and analytic results for some toy portfolio models we show that for relatively large values of r (e.g. 0.6) noise does, indeed, have the pronounced effect suggested by Galluccio et al. (1998), Laloux et al. (1999) and Plerou et al. (1999) and illustrated later by Laloux et al. (Int. J. Theor. Appl. Finance 3 (2000) 391), Plerou et al. (Phys. Rev. E, e-print cond-mat/0108023) and Rosenow et al. (Europhys. Lett., e-print cond-mat/0111537) in a portfolio optimization context, while for smaller r (around 0.2 or below), the error due to noise drops to acceptable levels. Since the length of available time series is for obvious reasons limited in any practical application, any bound imposed on the noise-induced error translates into a bound on the size of the portfolio. In a related set of experiments we find that the effect of noise depends also on whether the problem arises in asset allocation or in a risk measurement context: if covariance matrices are used simply for measuring the risk of portfolios with a fixed composition rather than as inputs to optimization, the
Applications of Random Matrices in Physics
NASA Astrophysics Data System (ADS)
Brezin, Edouard; Kazakov, Vladimir; Serban, Didina; Wiegmann, Paul; Zabrodin, Anton
Random matrices are widely and successfully used in physics for almost 60-70 years, beginning with the works of Dyson and Wigner. Although it is an old subject, it is constantly developing into new areas of physics and mathematics. It constitutes now a part of the generalculture of a theoretical physicist. Mathematical methods inspired by random matrix theory become more powerful, sophisticated and enjoy rapidly growing applications in physics. Recent examples include the calculation of universal correlations in the mesoscopic system, new applications in disordered and quantum chaotic systems, in combinatorial and growth models, as well as the recent breakthrough, due to the matrix models, in two dimensional gravity and string theory and the non-abelian gauge theories.
Association of scattering matrices in quantum networks
Almeida, F.A.G.; Macêdo, A.M.S.
2013-06-15
Algorithms based on operations that associate scattering matrices in series or in parallel (analogous to impedance association in a classical circuit) are developed here. We exemplify their application by calculating the total scattering matrix of several types of quantum networks, such as star graphs and a chain of chaotic quantum dots, obtaining results with good agreement with the literature. Through a computational-time analysis we compare the efficiency of two algorithms for the simulation of a chain of chaotic quantum dots based on series association operations of (i) two-by-two centers and (ii) three-by-three ones. Empirical results point out that the algorithm (ii) is more efficient than (i) for small number of open scattering channels. A direct counting of floating point operations justifies quantitatively the superiority of the algorithm (i) for large number of open scattering channels.
Investigation of degradation mechanisms in composite matrices
NASA Technical Reports Server (NTRS)
Giori, C.; Yamauchi, T.
1982-01-01
Degradation mechanisms were investigated for graphite/polysulfone and graphite/epoxy laminates exposed to ultraviolet and high-energy electron radiations in vacuum up to 960 equivalent sun hours and 10 to the ninth power rads respectively. Based on GC and combined GC/MS analysis of volatile by-products evolved during irradiation, several free radical mechanisms of composite degradation were identified. The radiation resistance of different matrices was compared in terms of G values and quantum yields for gas formation. All the composite materials evaluated show high electron radiation stability and relatively low ultraviolet stability as indicated by low G values and high quantum for gas formation. Mechanical property measurements of irradiated samples did not reveal significant changes, with the possible exception of UV exposed polysulfone laminates. Hydrogen and methane were identified as the main by-products of irradiation, along with unexpectedly high levels of CO and CO2.
Quantum State Tomography via Reduced Density Matrices
NASA Astrophysics Data System (ADS)
Xin, Tao; Lu, Dawei; Klassen, Joel; Yu, Nengkun; Ji, Zhengfeng; Chen, Jianxin; Ma, Xian; Long, Guilu; Zeng, Bei; Laflamme, Raymond
2017-01-01
Quantum state tomography via local measurements is an efficient tool for characterizing quantum states. However, it requires that the original global state be uniquely determined (UD) by its local reduced density matrices (RDMs). In this work, we demonstrate for the first time a class of states that are UD by their RDMs under the assumption that the global state is pure, but fail to be UD in the absence of that assumption. This discovery allows us to classify quantum states according to their UD properties, with the requirement that each class be treated distinctly in the practice of simplifying quantum state tomography. Additionally, we experimentally test the feasibility and stability of performing quantum state tomography via the measurement of local RDMs for each class. These theoretical and experimental results demonstrate the advantages and possible pitfalls of quantum state tomography with local measurements.
Nanocrystal/sol-gel nanocomposites
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.
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.
Nanocrystal/sol-gel nanocomposites
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
Hasenfeld, A.; Pepke, E.; Lim, H.A.; Cantor, C.R.
1993-12-31
A new agarose gel model is introduced, which corresponds to what the authors believe agarose gels look like microscopically. While the scientific literature is filled with studies of the microscopic structure of agarose, the fact remains that there is no unambiguous and exact model of its underlying structure. Given this, the authors are left to construct their own model numerically.
Novel Factor-loaded Polyphosphazene Matrices
Oredein-McCoy, Olugbemisola; Krogman, Nicholas R.; Weikel, Arlin L.; Hindenlang, Mark D.; Allcock, Harry R.; Laurencin, Cato T.
2009-01-01
Currently employed bone tissue engineered scaffolds often lack the potential for vascularization, which may be enhanced through the incorporation of and regulated release of angiogenic factors. For this reason, our objective was to fabricate and characterize protein-loaded amino acid ester polyphosphazene (Pphos)-based scaffolds and evaluate the novel sintering method used for protein incorporation, a method which will ultimately allow for the incorporation of proangiogenic agents. To test the hypothesis, Pphos and their composite microspheres with nanocrystalline hydroxyapatite (Pphos-HAp) were fabricated via the emulsion solvent evaporation method. Next, bovine serum albumin (BSA)-containing microsphere matrices were created using a novel solvent-non solvent approach for protein loading. The resulting protein (BSA) loaded-circular porous microsphere based scaffolds were characterized for morphology, porosity, protein structure, protein distribution, and subsequent protein release pattern. Scanning electron microscopy revealed porous microsphere scaffolds with a smooth surface and sufficient level of sintering, illustrated by fusion of adjacent microspheres. The porosity measured for the PNPhGly and PNPhGly-HAp scaffolds were 23 +/- 0.11% and 18+/- 4.02%, respectively, and within the range of trabecular bone. Circular dichroism confirmed an intact secondary protein structure for BSA following the solvent sintering method used for loading, and confocal microscopy verified that FITC-BSA was successfully entrapped both between adjacent microspheres and within the surface of the microspheres while sintering. For both Pphos and their composite microsphere scaffolds, BSA was released at a steady rate over a 21day time period, following a zero order release profile. HAp particles in the composite scaffolds served to improve the release profile pattern, underscoring the potential of HAp for growth factor delivery. Moreover, the results of this work suggests that the
Dirac matrices for Chern-Simons gravity
NASA Astrophysics Data System (ADS)
Izaurieta, Fernando; Ramírez, Ricardo; Rodríguez, Eduardo
2012-10-01
A genuine gauge theory for the Poincaré, de Sitter or anti-de Sitter algebras can be constructed in (2n - 1)-dimensional spacetime by means of the Chern-Simons form, yielding a gravitational theory that differs from General Relativity but shares many of its properties, such as second order field equations for the metric. The particular form of the Lagrangian is determined by a rank n, symmetric tensor invariant under the relevant algebra. In practice, the calculation of this invariant tensor can be reduced to the computation of the trace of the symmetrized product of n Dirac Gamma matrices Γab in 2n-dimensional spacetime. While straightforward in principle, this calculation can become extremely cumbersome in practice. For large enough n, existing computer algebra packages take an inordinate long time to produce the answer or plainly fail having used up all available memory. In this talk we show that the general formula for the trace of the symmetrized product of 2n Gamma matrices Γab can be written as a certain sum over the integer partitions s of n, with every term being multiplied by a numerical cofficient αs. We then give a general algorithm that computes the α-coefficients as the solution of a linear system of equations generated by evaluating the general formula for different sets of tensors Bab with random numerical entries. A recurrence relation between different coefficients is shown to hold and is used in a second, "minimal" algorithm to greatly speed up the computations. Runtime of the minimal algorithm stays below 1 min on a typical desktop computer for up to n = 25, which easily covers all foreseeable applications of the trace formula.
Robust Generalized Low Rank Approximations of Matrices.
Shi, Jiarong; Yang, Wei; Zheng, Xiuyun
2015-01-01
In recent years, the intrinsic low rank structure of some datasets has been extensively exploited to reduce dimensionality, remove noise and complete the missing entries. As a well-known technique for dimensionality reduction and data compression, Generalized Low Rank Approximations of Matrices (GLRAM) claims its superiority on computation time and compression ratio over the SVD. However, GLRAM is very sensitive to sparse large noise or outliers and its robust version does not have been explored or solved yet. To address this problem, this paper proposes a robust method for GLRAM, named Robust GLRAM (RGLRAM). We first formulate RGLRAM as an l1-norm optimization problem which minimizes the l1-norm of the approximation errors. Secondly, we apply the technique of Augmented Lagrange Multipliers (ALM) to solve this l1-norm minimization problem and derive a corresponding iterative scheme. Then the weak convergence of the proposed algorithm is discussed under mild conditions. Next, we investigate a special case of RGLRAM and extend RGLRAM to a general tensor case. Finally, the extensive experiments on synthetic data show that it is possible for RGLRAM to exactly recover both the low rank and the sparse components while it may be difficult for previous state-of-the-art algorithms. We also discuss three issues on RGLRAM: the sensitivity to initialization, the generalization ability and the relationship between the running time and the size/number of matrices. Moreover, the experimental results on images of faces with large corruptions illustrate that RGLRAM obtains the best denoising and compression performance than other methods.
Robust Generalized Low Rank Approximations of Matrices
Shi, Jiarong; Yang, Wei; Zheng, Xiuyun
2015-01-01
In recent years, the intrinsic low rank structure of some datasets has been extensively exploited to reduce dimensionality, remove noise and complete the missing entries. As a well-known technique for dimensionality reduction and data compression, Generalized Low Rank Approximations of Matrices (GLRAM) claims its superiority on computation time and compression ratio over the SVD. However, GLRAM is very sensitive to sparse large noise or outliers and its robust version does not have been explored or solved yet. To address this problem, this paper proposes a robust method for GLRAM, named Robust GLRAM (RGLRAM). We first formulate RGLRAM as an l1-norm optimization problem which minimizes the l1-norm of the approximation errors. Secondly, we apply the technique of Augmented Lagrange Multipliers (ALM) to solve this l1-norm minimization problem and derive a corresponding iterative scheme. Then the weak convergence of the proposed algorithm is discussed under mild conditions. Next, we investigate a special case of RGLRAM and extend RGLRAM to a general tensor case. Finally, the extensive experiments on synthetic data show that it is possible for RGLRAM to exactly recover both the low rank and the sparse components while it may be difficult for previous state-of-the-art algorithms. We also discuss three issues on RGLRAM: the sensitivity to initialization, the generalization ability and the relationship between the running time and the size/number of matrices. Moreover, the experimental results on images of faces with large corruptions illustrate that RGLRAM obtains the best denoising and compression performance than other methods. PMID:26367116
Mono- and biphotonic photochemistry in glass matrices
NASA Astrophysics Data System (ADS)
Kaupp, Gerd
2006-04-01
Photochemistry in hard glassy solvent matrices gives different results than in gas matrices. It is performed at 83, 77, and ≥10 K by continuous irradiation and by pulsed multi MW cm -2 peak intensity excitation for those systems that do not react monophotonically. The highly structured matrix spectra should be taken as a basis for the interpretation of transient spectra to avoid ambiguities. Numerous [2.2]paracyclophanes are photolyzed. Most of them give stable diradical and quinodimethane spectra in addition to fluorescence and phosphorescence. Some benzylic diradicals undergo chemiluminescence after their photochemical generation. Matrix isolation spectroscopy is at variance with common interpretations in the lepidopterene case. A [2+4]-photocycloreversion of a substituted cyclohexene at 83 K leads to diene stereoisomers/rotamers that isomerize upon further irradiation. E/Z-photoequilibria are obtained in MTHF matrix from both sides with ω-nitrostyrene and α-benzylidene-γ-butyrolactone at 83 K, the latter stereoisomerization was also successfully studied at 10 K. Pulsed irradiation of technical photostabilizers at 10 K leads to stable zwitterion formation by proton migration that cannot be seen by continuous excitation. Inter- and intramolecular donor acceptor systems provide stable charge separation at 15 or 77 K upon pulsed laser irradiation and radicalanion spectra are recorded. Biphotonic photochemistry at ≥10 K allows for the formation of new ring systems such as dioxathiirane ( cyclo-SO 2), several aryldioxaziridines, and an electron rich triaziridine, compounds that revert upon thawing and could not be obtained by continuous irradiation, except cyclo-SO 2 that can also be formed after absorption of the long lived SO 2 triplet by another two-photon process.
Shin, S C; Bum, J P; Choi, J S
2000-11-19
The pharmacokinetics and bioavailability of triamcinolone acetonide were determined to investigate buccal absorption from the mucoadhesive gels in rabbits. The enhancing effect of sodium deoxycholate as an enhancer on the buccal absorption of triamcinolone acetonide from the mucoadhesive gels was evaluated in rabbits. Thus, 2 mg/kg of triamcinolone acetonide was administered from the mucoadhesive gels containing an enhancer (enhancer group) or not (control group) via the buccal routes and compared with intravenous routes (1 mg/kg, i.v. group). AUC of the control, enhancer and i.v group were 2374+/-915, 3778+/-1721 and 3945+/-2085 h ng/ml, respectively, and the absolutive bioavailability of enhancer or i.v to control group were 159.14 or 332.35%, respectively. The average C(max) of control and enhancer group were 263+/-159 and 362+/-201 ng/ml, and the mean T(max) of the control group and enhancer group were 5.00+/-1.67 and 4.33+/-0.82 h, respectively, but there was no significant difference. As the triamcinolone acetonide gels containing sodium deoxycholate as an enhancer was administered to rabbits via the buccal routes, the relative bioavailability showed about 1.59-fold compared with the control group. Buccal administration of triamcinolone acetonide gels containing sodium deoxycholate as an enhancer to rabbits showed a relatively constant, sustained blood concentration with minimal fluctuation.
Plutonium(IV) precipitates formed in alkaline media in the presence of various anions
Krot, N.N.; Shilov, V.P.; Yusov, A.B.; Tananaev, I.G.; Grigoriev, M.S.; Garnov, A.Yu.; Perminov, V.P.; Astafurova, L.N.
1998-09-01
The tendency of Pu(IV) to hydrolyze and form true solutions, colloid solutions, or insoluble precipitates has been known since the Manhattan Project. Since then, specific studies have been performed to examine in detail the equilibria of Pu(IV) hydrolytic reactions in various media. Great attention also has been paid to the preparation, structure, and properties of Pu(IV) polymers or colloids. These compounds found an important application in sol-gel technology for the preparation of nuclear fuel materials. A most important result of these works was the conclusion that Pu(IV) hydroxide, after some aging, consists of very small PuO{sub 2} crystallites and should therefore be considered to be Pu(IV) hydrous oxide. However, studies of the properties and behavior of solid Pu(IV) hydroxide in complex heterogeneous systems are rare. The primary goal of this investigation was to obtain data on the composition and properties of Pu(IV) hydrous oxide or other compounds formed in alkaline media under different conditions. Such information is important to understand Pu(IV) behavior and the forms of its existence in the Hanford Site alkaline tank waste sludge. This knowledge then may be applied in assessing plutonium criticality hazards in the storage, retrieval, and treatment of Hanford Site tank wastes as well as in understanding its contribution to the transuranic waste inventory (threshold at 100 nCi/g or about 5 {times} 10{sup {minus}6} M) of the separate solution and solid phases.
FY 2002 Report on Software Visualization Techniques for IV and V
NASA Technical Reports Server (NTRS)
Fotta, Michael E.
2002-01-01
One of the major challenges software engineers often face in performing IV&V is developing an understanding of a system created by a development team they have not been part of. As budgets shrink and software increases in complexity, this challenge will become even greater as these software engineers face increased time and resource constraints. This research will determine which current aspects of providing this understanding (e.g., code inspections, use of control graphs, use of adjacency matrices, requirements traceability) are critical to the performing IV&V and amenable to visualization techniques. We will then develop state-of-the-art software visualization techniques to facilitate the use of these aspects to understand software and perform IV&V.
Living bacteria in silica gels
NASA Astrophysics Data System (ADS)
Nassif, Nadine; Bouvet, Odile; Noelle Rager, Marie; Roux, Cécile; Coradin, Thibaud; Livage, Jacques
2002-09-01
The encapsulation of enzymes within silica gels has been extensively studied during the past decade for the design of biosensors and bioreactors. Yeast spores and bacteria have also been recently immobilized within silica gels where they retain their enzymatic activity, but the problem of the long-term viability of whole cells in an inorganic matrix has never been fully addressed. It is a real challenge for the development of sol-gel processes. Generic tests have been performed to check the viability of Escherichia coli bacteria in silica gels. Surprisingly, more bacteria remain culturable in the gel than in an aqueous suspension. The metabolic activity of the bacteria towards glycolysis decreases slowly, but half of the bacteria are still viable after one month. When confined within a mineral environment, bacteria do not form colonies. The exchange of chemical signals between isolated bacteria rather than aggregates can then be studied, a point that could be very important for 'quorum sensing'.
Efficient quantum circuits for Toeplitz and Hankel matrices
NASA Astrophysics Data System (ADS)
Mahasinghe, A.; Wang, J. B.
2016-07-01
Toeplitz and Hankel matrices have been a subject of intense interest in a wide range of science and engineering related applications. In this paper, we show that quantum circuits can efficiently implement sparse or Fourier-sparse Toeplitz and Hankel matrices. This provides an essential ingredient for solving many physical problems with Toeplitz or Hankel symmetry in the quantum setting with deterministic queries.
Asymptotic Spectra Of Banded Quasi-Toeplitz Matrices
NASA Technical Reports Server (NTRS)
Beam, Richard; Warming, Robert
1995-01-01
Paper presents theoretical and numerical study of asymptotic spectra of eigenvalues of banded Toeplitz and quasi-Toeplitz matrices. Emphasis in study on non-normal banded Toeplitz and quasi-Toeplitz matrices of arbitrarily large order and relatively small bandwidth.
Infinite Töplitz Lipschitz matrices and operators
NASA Astrophysics Data System (ADS)
Eliasson, H. L.; Kuksin, S. B.
2008-01-01
We introduce a class of infinite matrices {(A_{ss', s, s' in mathbb{Z}^d)} , which are asymptotically ( as | s| + | s'| → ∞) close to Hankel Töplitz matrices. We prove that this class forms an algebra, and that flow-maps of nonautonomous linear equations with coefficients from the class also belong to it.
The Modern Origin of Matrices and Their Applications
ERIC Educational Resources Information Center
Debnath, L.
2014-01-01
This paper deals with the modern development of matrices, linear transformations, quadratic forms and their applications to geometry and mechanics, eigenvalues, eigenvectors and characteristic equations with applications. Included are the representations of real and complex numbers, and quaternions by matrices, and isomorphism in order to show…
Component Identification and Item Difficulty of Raven's Matrices Items.
ERIC Educational Resources Information Center
Green, Kathy E.; Kluever, Raymond C.
Item components that might contribute to the difficulty of items on the Raven Colored Progressive Matrices (CPM) and the Standard Progressive Matrices (SPM) were studied. Subjects providing responses to CPM items were 269 children aged 2 years 9 months to 11 years 8 months, most of whom were referred for testing as potentially gifted. A second…
Computing Vibration-Mode Matrices From Finite-Element Output
NASA Technical Reports Server (NTRS)
Levy, Roy
1993-01-01
Postprocessing algorithms devised to facilitate vibrational-mode analyses of dynamics of complicated structures. Yields inertia matrices and elastic/rigid-coupling matrices. Such analyses important in simulation and control in active suppression of vibrations in large building or in precise aiming of large antenna.
User-Friendly Tools for Random Matrices: An Introduction
2012-12-03
zeros of the Riemann zeta function [Mon73]). 1.2 The Modern Random Matrix By now, random matrices are ubiquitous. They arise throughout modern ... mathematics and statistics, as well as in many branches of science and engineering. Random matrices have sev- eral different purposes that we may wish to
Random Matrices, Combinatorics, Numerical Linear Algebra and Complex Networks
2012-02-16
Rudelson and R. Vershynin, The Littlewood -Offord Problem and invertibility of random matrices, Advances in Mathematics 218 (2008), 600–633. [25] L... Littlewood -Offord theorems and the condition number of random discrete matrices, Annals of Mathematics, to appear. [29] T. Tao and V. Vu, The condition
Time series, correlation matrices and random matrix models
Vinayak; Seligman, Thomas H.
2014-01-08
In this set of five lectures the authors have presented techniques to analyze open classical and quantum systems using correlation matrices. For diverse reasons we shall see that random matrices play an important role to describe a null hypothesis or a minimum information hypothesis for the description of a quantum system or subsystem. In the former case various forms of correlation matrices of time series associated with the classical observables of some system. The fact that such series are necessarily finite, inevitably introduces noise and this finite time influence lead to a random or stochastic component in these time series. By consequence random correlation matrices have a random component, and corresponding ensembles are used. In the latter we use random matrices to describe high temperature environment or uncontrolled perturbations, ensembles of differing chaotic systems etc. The common theme of the lectures is thus the importance of random matrix theory in a wide range of fields in and around physics.
Microencapsulation of bioactives in cross-linked alginate matrices by spray drying.
Santa-Maria, Monica; Scher, Herbert; Jeoh, Tina
2012-01-01
Microencapsulation of biomolecules, cells and chemicals is widely used in the food and pharmaceutical industries to improve stability, delivery and to control the release of encapsulated moieties. Among encapsulation matrices, alginate is preferred due to its low cost, biodegradability and biocompatibility. Current methods for producing stable alginate gels involve dropping alginate suspensions into divalent cation solutions. This procedure is difficult to scale-up and produces undesirably large alginate beads. In our novel encapsulation method, alginate gelation occurs during spray drying upon volatilisation of a base and rapid release of otherwise unavailable calcium ions. The resulting particles, with median particle sizes in the range 15-120 µm, are insoluble in solution. Cellulase and hemicellulase activities encapsulated by this method were not compromised during spray drying and remained stable over prolonged storage. The procedure described here offers a one-step alternative to other encapsulation methods that are costly and difficult to scale-up.
Confirmatory factor analysis of the WAIS-IV/WMS-IV.
Holdnack, James A; Xiaobin Zhou; Larrabee, Glenn J; Millis, Scott R; Salthouse, Timothy A
2011-06-01
The Wechsler Adult Intelligence Scale-fourth edition (WAIS-IV) and the Wechsler Memory Scale-fourth edition (WMS-IV) were co-developed to be used individually or as a combined battery of tests. The independent factor structure of each of the tests has been identified; however, the combined factor structure has yet to be determined. Confirmatory factor analysis was applied to the WAIS-IV/WMS-IV Adult battery (i.e., age 16-69 years) co-norming sample (n = 900) to test 13 measurement models. The results indicated that two models fit the data equally well. One model is a seven-factor solution without a hierarchical general ability factor: Verbal Comprehension, Perceptual Reasoning, Processing Speed, Auditory Working Memory, Visual Working Memory, Auditory Memory, and Visual Memory. The second model is a five-factor model composed of Verbal Comprehension, Perceptual Reasoning, Processing Speed, Working Memory, and Memory with a hierarchical general ability factor. Interpretative implications for each model are discussed.
NASA Astrophysics Data System (ADS)
Gyoneva, Lazarina
The glomerular basement membrane (GBM) is a vital part of the blood-urine filtration barrier in the kidneys. In healthy GBMs, the main tension-resisting component is alpha3(IV)alpha4(IV)alpha5(IV) type IV collagen, but in some diseases it is replaced by other collagen IV isoforms. As a result, the GBM becomes leaky and disorganized, ultimately resulting in kidney failure. Our goal is to understanding the biomechanical aspects of the alpha3(IV)alpha4(IV)alpha5(IV) chains and how their absence could be responsible for (1) the initial injury to the GBM and (2) progression to kidney failure. A combination of experiments and computational models were designed for that purpose. A model basement membrane was used to compare experimentally the distensibility of tissues with the alpha3(IV)alpha4(IV)alpha5(IV) chains present and missing. The experiments showed basement membranes containing alpha3(IV)alpha4(IV)alpha5(IV) chains were less distensible. It has been postulated that the higher level of lateral cross-linking (supercoiling) in the alpha3(IV)alpha4(IV)alpha5(IV) networks contributes additional strength/stability to basement membranes. In a computational model of supercoiled networks, we found that supercoiling greatly increased the stiffness of collagen IV networks but only minimally decreased the permeability, which is well suited for the needs of the GBM. It is also known that the alpha3(IV)alpha4(IV)alpha5(IV) networks are more protected from enzymatic degradation, and we explored their significance in GBM remodeling. Our simulations showed that the more protected network was needed to prevent the system from entering a dangerous feedback cycle due to autoregulation mechanisms in the kidneys. Overall, the work adds to the evidence of biomechanical differences between the alpha3(IV)alpha4(IV)alpha5(IV) networks and other collagen IV networks, points to supercoiling as the main source of biomechanical differences, discusses the suitability of alpha3(IV)alpha4(IV
Matěj, Zdeněk; Mokso, Rajmund; Larsson, Krister; Hardion, Vincent; Spruce, Darren
2017-01-01
The MAX IV Laboratory is currently the synchrotron X-ray source with the beam of highest brilliance. Four imaging beamlines are in construction or in the project phase. Their common characteristic will be the high acquisition rates of phase-enhanced images. This high data flow will be managed at the local computing cluster jointly with the Swedish National Computing Infrastructure. A common image reconstruction and analysis platform is being designed to offer reliable quantification of the multidimensional images acquired at all the imaging beamlines at MAX IV.
Tissue engineered cartilage on collagen and PHBV matrices.
Köse, Gamze Torun; Korkusuz, Feza; Ozkul, Aykut; Soysal, Yasemin; Ozdemir, Taner; Yildiz, Cemil; Hasirci, Vasif
2005-09-01
Cartilage engineering is a very novel approach to tissue repair through use of implants. Matrices of collagen containing calcium phosphate (CaP-Gelfix), and matrices of poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) (PHBV) were produced to create a cartilage via tissue engineering. The matrices were characterized by scanning electron microscopy (SEM) and electron diffraction spectroscopy (EDS). Porosity and void volume analysis were carried out to characterize the matrices. Chondrocytes were isolated from the proximal humerus of 22 week-old male, adult, local albino rabbits. For cell type characterization, Type II collagen was measured by Western Blot analysis. The foams were seeded with 1x10(6) chondrocytes and histological examinations were carried out to assess cell-matrix interaction. Macroscopic examination showed that PHBV (with or without chondrocytes) maintained its integrity for 21 days, while CaP-Gelfix was deformed and degraded within 15 days. Cell-containing and cell-free matrices were implanted into full thickness cartilage defects (4.5 mm in diameter and 4 mm in depth) at the patellar groove on the right and left knees of eight rabbits, respectively. In vivo results at 8 and 20 weeks with chondrocyte seeded PHBV matrices presented early cartilage formation resembling normal articular cartilage and revealed minimal foreign body reaction. In CaP-Gelfix matrices, fibrocartilage formation and bone invasion was noted in 20 weeks. Cells maintained their phenotype in both matrices. PHBV had better healing response than CaP-Gelfix. Both matrices were effective in cartilage regeneration. These matrices have great potential for use in the repair of joint cartilage defects.
Ediage, E Njumbe; Di Mavungu, J Diana; Goryacheva, I Y; Van Peteghem, C; De Saeger, S
2012-04-01
Two multi-analyte flow-through immunoassay formats for rapid detection of mycotoxins in a variety of food matrices (peanut cake, maize, and cassava flour) were developed and evaluated. The selected food matrices are typical staple foods and export products for most low-income communities around the world. The assay formats included gel-based and membrane-based flow-through assays and were based on the principle of indirect enzyme-linked immunosorbent assay. Using the same immunoreagents, the performance characteristics of both assays were compared. To the best of our knowledge, this is the first report on such a comparison. The gel-based format was developed to screen for ochratoxin A, fumonisin B(1), deoxynivalenol, and zearalenone detection at cut-off values of 3, 1,250, 1,000, and 200 μg kg(-1), respectively, while the membrane-based format can be used to screen ochratoxin A, aflatoxin B(1,) deoxynivalenol, and zearalenone at the following cut-offs: 3, 5, 700, and 175 μg kg(-1), respectively. The applicability of these assay formats was demonstrated by evaluating the performance characteristics of both tests through performing multiple experiments on different days. Both assays were further evaluated by analyzing naturally contaminated samples in the laboratory and also in the field under tropical conditions (Cameroon, West Africa). The false-negative rate with both formats was less than 5%, which is in good agreement with Commission Decision 2002/657/EC regarding the performance of analytical methods intended for screening purposes.
Validation of analytical methods for ethyl carbamate in nine food matrices.
Ryu, Dayeon; Choi, Bogyoung; Kim, Nayoung; Koh, Eunmi
2016-11-15
Ethyl carbamate (EC) is formed through a reaction between ethanol and either cyanate or N-carbamyl compounds. This study aimed to develop and validate analytical methods for EC determination in nine food matrices: apple juice, soju, milk, corn oil, rice porridge, peanut butter, beef, flat fish, and sea mustard. Differences from AOAC procedure were use of d5-EC as internal standard, dilution of alcohol content, removal of lipophilic compounds by hexane, and removal of hydrophilic polysaccharides by gel-forming. Standard curves had a good linearity (R(2)>0.997) in all matrices tested. LOD and LOQ were in the range of 0.69-6.08μg/kg and 2.10-18.43μg/kg, respectively. Recovery rates ranged from 80.75 to 121.82% for intra-day and ranged from 78.84 to 116.98% for inter-day. The relative standard deviations (RSDs) were below 14%. These results indicate that the established methods can be applied to determine EC in a variety of foods.
Recent Advances with the AMPX Covariance Processing Capabilities in PUFF-IV
Wiarda, D. Arbanas, G.; Leal, L.; Dunn, M.E.
2008-12-15
The program PUFF-IV is used to process resonance parameter covariance information given in ENDF/B File 32 and point wise covariance matrices given in ENDF/B File 33 into group-averaged covariances matrices on a user-supplied group structure. For large resonance covariance matrices, found for example in {sup 235}U, the execution time of PUFF-IV can be quite long. Recently the code was modified to take advantage of Basic Linear Algebra Subprograms (BLAS) routines for the most time-consuming matrix multiplications. This led to a substantial decrease in execution time. This faster processing capability allowed us to investigate the conversion of File 32 data into File 33 data using a larger number of user-defined groups. While conversion substantially reduces the ENDF/B file size requirements for evaluations with a large number of resonances, a trade-off is made between the number of groups used to represent the resonance parameter covariance as a point wise covariance matrix and the file size. We are also investigating a hybrid version of the conversion, in which the low-energy part of the File 32 resonance parameter covariances matrix is retained and the correlations with higher energies as well as the high energy part are given in File 33.
Recent Advances with the AMPX Covariance Processing Capabilities in PUFF-IV
Wiarda, Dorothea; Arbanas, Goran; Leal, Luiz C; Dunn, Michael E
2008-01-01
The program PUFF-IV is used to process resonance parameter covariance information given in ENDF/B File 32 and point-wise covariance matrices given in ENDF/B File 33 into group-averaged covariances matrices on a user-supplied group structure. For large resonance covariance matrices, found for example in 235U, the execution time of PUFF-IV can be quite long. Recently the code was modified to take advandage of Basic Linear Algebra Subprograms (BLAS) routines for the most time-consuming matrix multiplications. This led to a substantial decrease in execution time. This faster processing capability allowed us to investigate the conversion of File 32 data into File 33 data using a larger number of user-defined groups. While conversion substantially reduces the ENDF/B file size requirements for evaluations with a large number of resonances, a trade-off is made between the number of groups used to represent the resonance parameter covariance as a point-wise covariance matrix and the file size. We are also investigating a hybrid version of the conversion, in which the low-energy part of the File 32 resonance parameter covariances matrix is retained and the correlations with higher energies as well as the high energy part are given in File 33.
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
Adhesive, elastomeric gel impregnating composition
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.
Polyoxometalate-based Supramolecular Gel
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
Wójcik, A; Lobarzewski, J; Błaszczyńska, T
1990-01-01
Three types of organic polymers and bead-shape silica gels were activated by graft polymerization of 2,3-epoxypropyl methacrylate; in some cases, epoxide groups on the support surface were modified to NH2 groups. Eight active matrices so obtained were assessed as supports for immobilized enzymes using peroxidase, glucoamylase and urease. The immobilization yield of protein and specific activities of enzymes were better with supports containing NH2 groups than with those containing epoxide spacer arms. Maximum enzyme immobilization and storage stabilities were obtained with silica-gel beads activated by graft polymerization of 2,3-epoxypropyl methacrylate. With all eight matrices tested, the immobilized enzymes showed good stability with not less than 82% of the original activity persisting after 28 days. The developed matrices have potential for use in process-scale biotechnological operations.
Jararhagin disruption of endothelial cell anchorage is enhanced in collagen enriched matrices.
Baldo, C; Lopes, D S; Faquim-Mauro, E L; Jacysyn, J F; Niland, S; Eble, J A; Clissa, P B; Moura-da-Silva, A M
2015-12-15
Hemorrhage is one of the most striking effects of bites by viper snakes resulting in fast bleeding and ischemia in affected tissues. Snake venom metalloproteinases (SVMPs) are responsible for hemorrhagic activity, but the mechanisms involved in SVMP-induced hemorrhage are not entirely understood and the study of such mechanisms greatly depends on in vivo experiments. In vivo, hemorrhagic SVMPs accumulate on basement membrane (BM) of venules and capillary vessels allowing the hydrolysis of collagen IV with consequent weakness and rupture of capillary walls. These effects are not reproducible in vitro with conventional endothelial cell cultures. In this study we used two-dimension (2D) or three-dimension (3D) cultures of HUVECs on matrigel and observed the same characteristics as in ex vivo experiments: only the hemorrhagic toxin was able to localize on surfaces or internalize endothelial cells in 2D cultures or in the surface of tubules formed on 3D cultures. The contribution of matrigel, fibronectin and collagen matrices in jararhagin-induced endothelial cell damage was then analyzed. Collagen and matrigel substrates enhanced the endothelial cell damage induced by jararhagin allowing toxin binding to focal adhesions, disruption of stress fibers, detachment and apoptosis. The higher affinity of jararhagin to collagen than to fibronectin explains the localization of the toxin within BM. Moreover, once located in BM, interactions of jararhagin with α2β1 integrin would favor its localization on focal adhesions, as observed in our study. The accumulation of toxin in focal adhesions, observed only in cells grown in collagen matrices, would explain the enhancement of cell damage in these matrices and reflects the actual interaction among toxin, endothelial cells and BM components that occurs in vivo and results in the hemorrhagic lesions induced by viper venoms.
Goñi, I; Ferrero, M C; Jiménez-Castellanos, R M; Gurruchaga, M
2002-10-01
Hydrophilic matrices are an interesting option when developing drug delivery systems. With this aim, hydroxypropyl methacrylate was grafted onto hydroxypropyl starch and hydroxypropyl cellulose substrates by following the Ce(IV) redox initiation method. Different amounts of ethyleneglycol' dimethacrylate, 7 and 34 mol%, as the crosslinking monomer, were also added. The drying of grafted products was carried out by lyophilization, obtaining white powders. Reaction yields (percent grafting, grafting efficiency, etc.) and some physical characteristics of the powders (particle size, moisture uptake, density, morphology, etc.) were determined. These parameters indicate how useful these products may be as potential matrices for direct compressed tablets. In this light, the powder flowability and the binding properties of each copolymer were determined. The graft copolymers can be considered of great interest as direct compression excipients. Due to their different chemical structure and composition, they showed differences in viscoelastic properties that revealed an interesting range of possibilities for use in drug delivery formulations. Tablets formulated with conventional excipients were also tested. Dissolution tests of various tablets were carried out. In 12 hr, 60-80% of the model drugs was released.
Mechanically implementable accommodation matrices for passive force control
Goswami, A.; Peshkin, M.
1999-08-01
Robot force control implemented by means of passive mechanical devices has inherent advantages over active implementations with regard to stability, response rapidity, and physical robustness. The class of devices considered in this paper consists of a Stewart platform-type mechanism interconnected with a network of adjustable mechanical elements such as springs and dampers. The control law repertoire of such a device, imagined as a robot wrist, is given by the range of admittance matrices that it may be programmed to possess. This paper focuses on wrists incorporating damper networks for which the admittance matrices reduce to accommodation or inverse-damping matrices. The authors show that a hydraulic network of fully adjustable damper elements may attain any diagonally dominant accommodation matrix. They describe the technique of selecting the individual damping coefficients to design a desired matrix. They identify the set of dominant matrices as a polyhedral convex cone in the space of matrix entries, and show that each dominant matrix can be composed of a positive linear combination of a fixed set of basis matrices. The overall wrist-accommodation matrix is obtained by projecting the accommodation matrix of the damper network through the wrist kinematics. The linear combination of the dominant basis matrices projected through the wrist kinematics generates the entire space of mechanically implementable force-control laws. The authors quantify the versatility of mechanically implementable force-control laws by comparing this space to the space of all matrices.
Dynamic Condensation of Mass and Stiffness Matrices
NASA Astrophysics Data System (ADS)
Zhang, N.
1995-12-01
Details are given of a procedure for condensing the mass and stiffness matrices of a structure for dynamic analysis. The condensed model is based on choosing ncnatural frequencies and the corresponding modes of original model. The model is constructed so that (1) it has ncnatural frequencies equal to those of the original model, (2) the modes φ ifcless than i,j = 1, 2, . . . , ncare the same as those for the master co-ordinates in the corresponding modes of the original and (3) the responses of the condensed system at the co-ordinates Xcdue to forces at these co-ordinates, at one particular chosen frequency, are the same as those of the original system. The natural frequencies, the corresponding modes and the dynamic responses used for the condensation can be obtained from finite element analysis of the original structure. The method has been applied to the modelling of two common structures to examine its applicability. Comparisons between the performance of the condensed models obtained by means of the dynamic condensation method and that of the models obtained by the Guyan method have been conducted. The results of the example show that the condensed models determined by the dynamic condensation method retain the natural frequencies and modal shapes and perform better in describing the dynamic responses of the structures than do the corresponding models obtained by the Guyan method.
Nanostructured mesoporous silica matrices in nanomedicine.
Vallet-Regí, M
2010-01-01
In the last few years the biomedical research field has shown a growing interest towards nanostructured mesoporous silica materials, whose chemical composition is silica and present nanometric pores. These bioceramics exhibit two important features: they can regenerate osseous tissues--the bond bioactivity of these materials has been confirmed by the formation of biological-like nanoapatites on their surface when in contact with physiological fluids--and they are able to act as controlled release systems. Drugs in the nanometre scale can be loaded on those matrices and then locally released in a controlled fashion. It is possible to chemically modify the silica walls to favour the adsorption of certain biomolecules such as peptides, proteins or growth factors. It is even possible to design smart biomaterials where the drug is released under an external stimulus. Thus, looking at all those properties, a question arises: Have these bioceramics good expectations to be used in clinical medical practice? Their biocompatibility, bioactivity, capacity to regenerate bone and ability to act as controlled release systems of biologically active species have been confirmed. In fact, their preliminary in vitro and in vivo essays have been positive. Now it is the time to adequate all these properties to the actual clinical problems, and to evaluate their efficiency in comparison with materials already known and currently employed such as bioglasses.
Photochemistry of glycolaldehyde in cryogenic matrices
Chin, W. Chevalier, M.; Thon, R.; Crépin, C.; Pollet, R.
2014-06-14
The photochemistry of glycolaldehyde (GA) upon irradiation at 266 nm is investigated in argon, nitrogen, neon, and para-hydrogen matrices by IR spectroscopy. Isomerization and fragmentation processes are found to compete. The hydrogen-bonded Cis-Cis form of GA is transformed mainly to the open Trans-Trans conformer and to CO and CH{sub 3}OH fragments and their mixed complexes. Different photo-induced behaviours appear depending on the matrix. In nitrogen, small amounts of Trans-Gauche and Trans-Trans conformers are detected after deposition and grow together upon irradiation. The Trans-Gauche conformer is characterized for the first time. In para-hydrogen due to a weaker cage effect additional H{sub 2}CO and HCO fragments are seen. Calculations of the potential energy surfaces of S{sub 0}, S{sub 1}, and T{sub 1} states – to analyse the torsional deformations which are involved in the isomerization process – and a kinetic analysis are presented to investigate the different relaxation pathways of GA. Fragmentation of GA under UV irradiation through the CO+CH{sub 3}OH molecular channel is a minor process, as in the gas phase.
Generalized graph states based on Hadamard matrices
Cui, Shawn X.; Yu, Nengkun; Zeng, Bei
2015-07-15
Graph states are widely used in quantum information theory, including entanglement theory, quantum error correction, and one-way quantum computing. Graph states have a nice structure related to a certain graph, which is given by either a stabilizer group or an encoding circuit, both can be directly given by the graph. To generalize graph states, whose stabilizer groups are abelian subgroups of the Pauli group, one approach taken is to study non-abelian stabilizers. In this work, we propose to generalize graph states based on the encoding circuit, which is completely determined by the graph and a Hadamard matrix. We study the entanglement structures of these generalized graph states and show that they are all maximally mixed locally. We also explore the relationship between the equivalence of Hadamard matrices and local equivalence of the corresponding generalized graph states. This leads to a natural generalization of the Pauli (X, Z) pairs, which characterizes the local symmetries of these generalized graph states. Our approach is also naturally generalized to construct graph quantum codes which are beyond stabilizer codes.
Partitioning sparse matrices with eigenvectors of graphs
NASA Technical Reports Server (NTRS)
Pothen, Alex; Simon, Horst D.; Liou, Kang-Pu
1990-01-01
The problem of computing a small vertex separator in a graph arises in the context of computing a good ordering for the parallel factorization of sparse, symmetric matrices. An algebraic approach for computing vertex separators is considered in this paper. It is shown that lower bounds on separator sizes can be obtained in terms of the eigenvalues of the Laplacian matrix associated with a graph. The Laplacian eigenvectors of grid graphs can be computed from Kronecker products involving the eigenvectors of path graphs, and these eigenvectors can be used to compute good separators in grid graphs. A heuristic algorithm is designed to compute a vertex separator in a general graph by first computing an edge separator in the graph from an eigenvector of the Laplacian matrix, and then using a maximum matching in a subgraph to compute the vertex separator. Results on the quality of the separators computed by the spectral algorithm are presented, and these are compared with separators obtained from other algorithms for computing separators. Finally, the time required to compute the Laplacian eigenvector is reported, and the accuracy with which the eigenvector must be computed to obtain good separators is considered. The spectral algorithm has the advantage that it can be implemented on a medium-size multiprocessor in a straightforward manner.
Decellularized matrices for cardiovascular tissue engineering
Moroni, Francesco; Mirabella, Teodelinda
2014-01-01
Cardiovascular disease (CVD) is one of the leading causes of death in the Western world. The replacement of damaged vessels and valves has been practiced since the 1950’s. Synthetic grafts, usually made of bio-inert materials, are long-lasting and mechanically relevant, but fail when it comes to “biointegration”. Decellularized matrices, instead, can be considered biological grafts capable of stimulating in vivo migration and proliferation of endothelial cells (ECs), recruitment and differentiation of mural cells, finally, culminating in the formation of a biointegrated tissue. Decellularization protocols employ osmotic shock, ionic and non-ionic detergents, proteolitic digestions and DNase/RNase treatments; most of them effectively eliminate the cellular component, but show limitations in preserving the native structure of the extracellular matrix (ECM). In this review, we examine the current state of the art relative to decellularization techniques and biological performance of decellularized heart, valves and big vessels. Furthermore, we focus on the relevance of ECM components, native and resulting from decellularization, in mediating in vivo host response and determining repair and regeneration, as opposed to graft corruption. PMID:24660110
Substituted amylose matrices for oral drug delivery
NASA Astrophysics Data System (ADS)
Moghadam, S. H.; Wang, H. W.; Saddar El-Leithy, E.; Chebli, C.; Cartilier, L.
2007-03-01
High amylose corn starch was used to obtain substituted amylose (SA) polymers by chemically modifying hydroxyl groups by an etherification process using 1,2-epoxypropanol. Tablets for drug-controlled release were prepared by direct compression and their release properties assessed by an in vitro dissolution test (USP XXIII no 2). The polymer swelling was characterized by measuring gravimetrically the water uptake ability of polymer tablets. SA hydrophilic matrix tablets present sequentially a burst effect, typical of hydrophilic matrices, and a near constant release, typical of reservoir systems. After the burst effect, surface pores disappear progressively by molecular association of amylose chains; this allows the creation of a polymer layer acting as a diffusion barrier and explains the peculiar behaviour of SA polymers. Several formulation parameters such as compression force, drug loading, tablet weight and insoluble diluent concentration were investigated. On the other hand, tablet thickness, scanning electron microscope analysis and mercury intrusion porosimetry showed that the high crushing strength values observed for SA tablets were due to an unusual melting process occurring during tabletting although the tablet external layer went only through densification, deformation and partial melting. In contrast, HPMC tablets did not show any traces of a melting process.
Modeling Covariance Matrices via Partial Autocorrelations
Daniels, M.J.; Pourahmadi, M.
2009-01-01
Summary We study the role of partial autocorrelations in the reparameterization and parsimonious modeling of a covariance matrix. The work is motivated by and tries to mimic the phenomenal success of the partial autocorrelations function (PACF) in model formulation, removing the positive-definiteness constraint on the autocorrelation function of a stationary time series and in reparameterizing the stationarity-invertibility domain of ARMA models. It turns out that once an order is fixed among the variables of a general random vector, then the above properties continue to hold and follows from establishing a one-to-one correspondence between a correlation matrix and its associated matrix of partial autocorrelations. Connections between the latter and the parameters of the modified Cholesky decomposition of a covariance matrix are discussed. Graphical tools similar to partial correlograms for model formulation and various priors based on the partial autocorrelations are proposed. We develop frequentist/Bayesian procedures for modelling correlation matrices, illustrate them using a real dataset, and explore their properties via simulations. PMID:20161018
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.
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
Diffusion of polymer gel implants.
Davis, B K
1974-08-01
Crosslinked polyacrylamide and polyvinylpyrrolidone gels have been used to subcutaneously implant (125)I-labeled immunoglobulin, (125)I-labeled luteinizing hormone, (125)I-labeled bovine serum albumin, (125)I-labeled insulin, [(3)H]prostaglandin F(2alpha), and Na(125)I into hamsters. From the rates of absorption of the solutes, their diffusion coefficients were determined. The diffusion coefficients showed a logarithmic dependence on implant polymer concentration and solute molecular weight. Release of the solutes from gel preparations incubated 10 mM phosphate buffer (pH 7.2) at 37 degrees revealed a similar relationship between solute diffusion coefficient, molecular weight, and the concentration of polymer. A general equation was derived that gives the expected diffusion coefficient of a substance in a polymer gel from its molecular weight, diffusion coefficient in solvent, and polymer concentration of the 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.
Asare-Addo, Kofi; Conway, Barbara R; Larhrib, Hassan; Levina, Marina; Rajabi-Siahboomi, Ali R; Tetteh, John; Boateng, Joshua; Nokhodchi, Ali
2013-11-01
The evaluation of the effects of different media ionic strengths and pH on the release of hydrochlorothiazide, a poorly soluble drug, and diltiazem hydrochloride, a cationic and soluble drug, from a gel forming hydrophilic polymeric matrix was the objective of this study. The drug to polymer ratio of formulated tablets was 4:1. Hydrochlorothiazide or diltiazem HCl extended release (ER) matrices containing hypromellose (hydroxypropyl methylcellulose (HPMC)) were evaluated in media with a pH range of 1.2-7.5, using an automated USP type III, Bio-Dis dissolution apparatus. The ionic strength of the media was varied over a range of 0-0.4M to simulate the gastrointestinal fed and fasted states and various physiological pH conditions. Sodium chloride was used for ionic regulation due to its ability to salt out polymers in the midrange of the lyotropic series. The results showed that the ionic strength had a profound effect on the drug release from the diltiazem HCl K100LV matrices. The K4M, K15M and K100M tablets however withstood the effects of media ionic strength and showed a decrease in drug release to occur with an increase in ionic strength. For example, drug release after the 1h mark for the K100M matrices in water was 36%. Drug release in pH 1.2 after 1h was 30%. An increase of the pH 1.2 ionic strength to 0.4M saw a reduction of drug release to 26%. This was the general trend for the K4M and K15M matrices as well. The similarity factor f2 was calculated using drug release in water as a reference. Despite similarity occurring for all the diltiazem HCl matrices in the pH 1.2 media (f2=64-72), increases of ionic strength at 0.2M and 0.4M brought about dissimilarity. The hydrochlorothiazide tablet matrices showed similarity at all the ionic strength tested for all polymers (f2=56-81). The values of f2 however reduced with increasing ionic strengths. DSC hydration results explained the hydrochlorothiazide release from their HPMC matrices. There was an increase in
Specific cleavage of human type III and IV collagens by Pseudomonas aeruginosa elastase.
Heck, L W; Morihara, K; McRae, W B; Miller, E J
1986-01-01
Purified Pseudomonas aeruginosa elastase cleaved human type III and IV collagens with the formation of specific cleavage products. Furthermore, type I collagen appeared to be slowly cleaved by both P. aeruginosa elastase and alkaline protease. These cleavage fragments from type III and IV collagens were separated from the intact collagen chains by SDS polyacrylamide gradient gel electrophoresis run under reducing conditions, and they were detected by their characteristic Coomassie blue staining pattern. The results of these studies suggest that the pathogenesis of tissue invasion and hemorrhagic tissue necrosis observed in P. aeruginosa infections may be related to the degradation of these collagen types by bacterial extracellular proteases. Images PMID:3079727
Actuation performances of anisotropic gels
NASA Astrophysics Data System (ADS)
Nardinocchi, P.; Teresi, L.
2016-12-01
We investigated the actuation performances of anisotropic gels driven by mechanical and chemical stimuli, in terms of both deformation processes and stroke-curves, and distinguished between the fast response of gels before diffusion starts and the asymptotic response attained at the steady state. We also showed as the range of forces that an anisotropic hydrogel can exert when constrained is especially wide; indeed, changing fiber orientation allows us to induce shear as well as transversely isotropic extensions.
Multiple phases of protien gels
NASA Astrophysics Data System (ADS)
Annaka, Masahiko; Tanaka, Toyoichi
1994-03-01
A multiple phase transition was observed in gels made by covalently cross-linking proteins in either native or denatured state. The enzymatic activity of the gels prepared from native α-chymotrypsin was determined for each of the multiple phases. The reversibility of the swelling degrees and the enzymatic reaction rates upon phase transition suggests that the protein is at a free energy minimum and thus in a phase.
Malloy, Jaret L; Veldhuizen, Ruud A W; Thibodeaux, Brett A; O'Callaghan, Richard J; Wright, Jo Rae
2005-02-01
Pulmonary surfactant has two distinct functions within the lung: reduction of surface tension at the air-liquid interface and participation in innate host defense. Both functions are dependent on surfactant-associated proteins. Pseudomonas aeruginosa is primarily responsible for respiratory dysfunction and death in cystic fibrosis patients and is also a leading pathogen in nosocomial pneumonia. P. aeruginosa secretes a number of proteases that contribute to its virulence. We hypothesized that P. aeruginosa protease IV degrades surfactant proteins and results in a reduction in pulmonary surfactant host defense and biophysical functions. Protease IV was isolated from cultured supernatant of P. aeruginosa by gel chromatography. Incubation of cell-free bronchoalveolar lavage fluid with protease IV resulted in degradation of surfactant proteins (SP)-A, -D, and -B. SPs were degraded in a time- and dose-dependent fashion by protease IV, and degradation was inhibited by the trypsin-like serine protease inhibitor Nalpha-p-tosyl-L-lysine-chloromethyl ketone (TLCK). Degradation by protease IV inhibited SP-A- and SP-D-mediated bacterial aggregation and uptake by macrophages. Surfactant treated with protease IV was unable to reduce surface tension as effectively as untreated surfactant, and this effect was inhibited by TLCK. We speculate that protease IV may be an important contributing factor to the development and propagation of acute lung injury associated with P. aeruginosa via loss of surfactant function within the lung.
Random matrices as models for the statistics of quantum mechanics
NASA Astrophysics Data System (ADS)
Casati, Giulio; Guarneri, Italo; Mantica, Giorgio
1986-05-01
Random matrices from the Gaussian unitary ensemble generate in a natural way unitary groups of evolution in finite-dimensional spaces. The statistical properties of this time evolution can be investigated by studying the time autocorrelation functions of dynamical variables. We prove general results on the decay properties of such autocorrelation functions in the limit of infinite-dimensional matrices. We discuss the relevance of random matrices as models for the dynamics of quantum systems that are chaotic in the classical limit. Permanent address: Dipartimento di Fisica, Via Celoria 16, 20133 Milano, Italy.
Bunch-Kaufman factorization for real symmetric indefinite banded matrices
NASA Technical Reports Server (NTRS)
Jones, Mark T.; Patrick, Merrell L.
1989-01-01
The Bunch-Kaufman algorithm for factoring symmetric indefinite matrices was rejected for banded matrices because it destroys the banded structure of the matrix. Herein, it is shown that for a subclass of real symmetric matrices which arise in solving the generalized eigenvalue problem using Lanczos's method, the Bunch-Kaufman algorithm does not result in major destruction of the bandwidth. Space time complexities of the algorithm are given and used to show that the Bunch-Kaufman algorithm is a significant improvement over LU factorization.
On the asymptotic distribution of block-modified random matrices
Arizmendi, Octavio; Nechita, Ion; Vargas, Carlos
2016-01-15
We study random matrices acting on tensor product spaces which have been transformed by a linear block operation. Using operator-valued free probability theory, under some mild assumptions on the linear map acting on the blocks, we compute the asymptotic eigenvalue distribution of the modified matrices in terms of the initial asymptotic distribution. Moreover, using recent results on operator-valued subordination, we present an algorithm that computes, numerically but in full generality, the limiting eigenvalue distribution of the modified matrices. Our analytical results cover many cases of interest in quantum information theory: we unify some known results and we obtain new distributions and various generalizations.
The explosive divergence in iterative maps of matrices
NASA Astrophysics Data System (ADS)
Navickas, Zenonas; Ragulskis, Minvydas; Vainoras, Alfonsas; Smidtaite, Rasa
2012-11-01
The effect of explosive divergence in generalized iterative maps of matrices is defined and described using formal algebraic techniques. It is shown that the effect of explosive divergence can be observed in an iterative map of square matrices of order 2 if and only if the matrix of initial conditions is a nilpotent matrix and the Lyapunov exponent of the corresponding scalar iterative map is greater than zero. Computational experiments with the logistic map and the circle map are used to illustrate the effect of explosive divergence occurring in iterative maps of matrices.
ANOVA like analysis for structured families of stochastic matrices
NASA Astrophysics Data System (ADS)
Dias, Cristina; Santos, Carla; Varadinov, Maria; Mexia, João T.
2016-12-01
Symmetric stochastic matrices width a width a dominant eigenvalue λ and the corresponding eigenvector α appears in many applications. Such matrices can be written as M =λ α αt+E¯. Thus β = λ α will be the structure vector. When the matrices in such families correspond to the treatments of a base design we can carry out a ANOVA like analysis of the action of the treatments in the model on the structured vectors. This analysis can be transversal-when we worked width homologous components and - longitudinal when we consider contrast on the components of each structure vector. The analysis will be briefly considered at the end of our presentation.
Synthetic polyion-counterion transport systems in polymersomes and gels.
Montenegro, Javier; Braun, Jörg; Fischer-Onaca, Ozana; Meier, Wolfgang; Matile, Stefan
2011-10-07
Transport across the membranes of polymersomes remains difficult in part due to the great thickness of the polymer bilayers. Here, we report that dynamic polyion-counterion transport systems are active in fluorogenic polymersomes composed of poly(dimethylsiloxane)-b-poly(2-methyloxazoline) (PDMS-PMOXA). These results suggest that counterion-activated calf-thymus DNA can act as cation carrier that moves not only across lipid bilayer and bulk chloroform membranes but also across the "plastic" membranes of polymersomes. Compared to egg yolk phosophatidylcholine (EYPC) lipsosomes, activities and activator scope in PDMS-PMOXA polymersomes are clearly reduced. Embedded in agar gel matrices, fluorogenic PDMS-PMOXA polymersomes respond reliably to polyion-counterion transporters, with high contrast, high stability and preserved selectivity. Compared to standard EYPC liposomes, it cannot be said that PDMS-PMOXA polymersomes are better. However, they are different, and this difference could be interesting for the development of sensing devices.
Facile Routes to Th(IV), U(IV), and Np(IV) Phosphites and Phosphates
Villa, Eric M.; Wang, Shuao; Alekseev, Evgeny V.; Depmeier, Wulf; Albrecht-Schmitt, Thomas E.
2011-08-05
Three actinide(IV) phosphites and a Np^{IV} phosphate, An^{IV}(HPO₃)₂(H₂O)₂ (An = Th, U, Np) and Cs[Np(H_{1.5}PO₄)(PO₄)]₂, respectively, were synthesized using mild hydrothermal conditions. The first three phases are isotypic and were obtained using similar reaction conditions. Cs[Np(H_{1.5}PO₄)(PO₄)]₂ was synthesized using an analogous method to that of Np(HPO₃)₂(H₂O)₂. However, this fourth phase is quite different in comparison to the other phases in both composition and structure. The structure of Cs[Np(H_{1.5}PO₄)(PO₄)]₂ is constructed from double layers of neptunium(IV) phosphate with caesium cations in the interlayer region. In contrast, An(HPO₃)₂(H₂O)₂ (An = Th, U, Np) form dense 3D networks. The actinide contraction is detected in variety of metrics obtained from single-crystal X-ray diffraction data. Changes in the oxidation state of the neptunium starting materials yield different products.
Topical Review: Polymer gel dosimetry
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
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.
Rheological characterization of hydroxypropylcellulose gels.
Ramachandran, S; Chen, S; Etzler, F
1999-02-01
The present paper describes the rheological properties of hydroxypropylcellulose (HPC) gels formulated in propylene glycol (PG), water, ethanol, and mixtures of these components. The effects of molecular weight, polymer concentration, and solvent composition on the apparent viscosity and flow characteristics have been studied by continuous shear rheometry. The HPC gels are shear thinning and do not exhibit significant yield or hysteresis in their rheograms. The apparent viscosity increases with increasing molecular weight and concentration of the polymer, as expected. Although not so pronounced at lower concentrations (< or = 1.5%), HPC gels tend to become increasingly non-Newtonian with increasing molecular weight at higher polymer concentrations (3%). A mathematical model has been proposed for the prediction of viscosities of HPC gels. There exists a high degree of dependence on molecular interactions between various solvent molecules in the prediction of mixture viscosities in ternary systems. The effects of solvent composition on the viscoelastic behavior of these gels have also been examined by dynamic mechanical analysis. The HPC gels are highly viscoelastic and exhibit greater degrees of elasticity with increased PG content in ternary solvent mixtures with water and ethanol. The study also suggests that dynamic mechanical analysis could prove to be a useful tool in the determination of zero-shear viscosities, viscosities that are representative of most realistic situations.
Leclercq, Amélie; Nonell, Anthony; Todolí Torró, José Luis; Bresson, Carole; Vio, Laurent; Vercouter, Thomas; Chartier, Frédéric
2015-07-23
Due to their outstanding analytical performances, inductively coupled plasma optical emission spectrometry (ICP-OES) and mass spectrometry (ICP-MS) are widely used for multi-elemental measurements and also for isotopic characterization in the case of ICP-MS. While most studies are carried out in aqueous matrices, applications involving organic/hydro-organic matrices become increasingly widespread. This kind of matrices is introduced in ICP based instruments when classical "matrix removal" approaches such as acid digestion or extraction procedures cannot be implemented. Due to the physico-chemical properties of organic/hydro-organic matrices and their associated effects on instrumentation and analytical performances, their introduction into ICP sources is particularly challenging and has become a full topic. In this framework, numerous theoretical and phenomenological studies of these effects have been performed in the past, mainly by ICP-OES, while recent literature is more focused on applications and associated instrumental developments. This tutorial review, divided in two parts, explores the rich literature related to the introduction of organic/hydro-organic matrices in ICP-OES and ICP-MS. The present Part I, provides theoretical considerations in connection with the physico-chemical properties of organic/hydro-organic matrices, in order to better understand the induced phenomena. This focal point is divided in four chapters highlighting: (i) the impact of organic/hydro-organic matrices from aerosol generation to atomization/excitation/ionization processes; (ii) the production of carbon molecular constituents and their spatial distribution in the plasma with respect to analytes repartition; (iii) the subsequent modifications of plasma fundamental properties; and (iv) the resulting spectroscopic and non spectroscopic interferences. This first part of this tutorial review is addressed either to beginners or to more experienced scientists who are interested in the
Contreras, L.; Melgoza, L. M.; Aguilar-de-Leyva, A.; Caraballo, I.
2012-01-01
Percolation theory has been applied in order to study the existence of critical points as well as the possibility to find a “combined percolation threshold” for ternary hydrophilic matrices prepared with HPMC, NaCMC, and theophylline. For this purpose, different batches of ternary as well as binary hydrophilic matrices have been prepared. Critical points have been found for binary hydrophilic matrices between 21.5 and 31.3% (v/v) of HPMC and between 39 and 54% (v/v) of NaCMC, respectively. In a previous work carried out with the same polymers but a much more soluble drug (KCl), it was demonstrated the existence of a partial collaboration between the polymers in order to establish the gel layer. In this work, it has been observed for the first time the need of a minimum concentration of one of the matrix-forming polymer (between 10 and 20% v/v, approximately) for establishing an effective collaboration. PMID:22919292
NASA Astrophysics Data System (ADS)
Nästren, C.; Fernandez, A.; Haas, D.; Somers, J.; Walter, M.
2007-05-01
The impact of Pu and Am, two elements that potentially pose a long term hazard for the disposal of spent nuclear fuel, can be abated by their reintroduction into the fuel cycle for transmutation. Such transmutation targets can be fabricated by a sol gel method for the production of porous inactive beads, which are then infiltrated by Am solutions. Following calcination, compaction into pellets and sintering, the product is obtained. At its heart, the sol gel process relies on an ammonia precipitation, so that it is not universally applicable. Therefore, an alternative is sought not just to overcome this chemical limitation, but also to simplify the process and reduce waste streams. The new concept utilises powder metallurgy routes (compaction, crushing and sieving) to produce porous, almost, dust free granules, which are infiltrated with the actinide nitrate. The method has been developed using yttria stabilised zirconia and alumina, and has been demonstrated for the production of Al2O3-AmO2 targets for neutron capture investigations. The results are very promising and meet light water reactor fuel specifications. In addition, the process is ideally suited for the production of ceramic matrices for conditioning actinides for geological disposal.
Gel-based versus gel-free proteomics: a review.
Baggerman, Geert; Vierstraete, Evy; De Loof, Arnold; Schoofs, Liliane
2005-12-01
With the sequencing of the genome of over 150 organisms, the field of biology has been revolutionised. Instead of studying one gene or protein at the time, it is now possible to study the effect of physiological or pathological changes on the expression of all genes or proteins in the organism. Proteomics aims at the simultaneous analysis of all proteins expressed by a cell, tissue or organism in a specific physiological condition. Because proteins are the effector molecules in all organisms, it is evident that changes in the physiological condition of an organism will be reflected by changes in protein expression and/or processing. Since the formulation of the concept of proteomics in the mid 90's proteomics has relied heavily on 2 dimensional gel electrophoresis (2DGE) for the separation and visualization of proteins. 2DGE, however, has a number of inherent drawbacks. 2DGE is costly, fairly insensitive to low copy proteins and cannot be used for the entire proteome. Therefore, over the years, several gel-free proteomics techniques have been developed to either fill the gaps left by 2DGE or to entirely abolish the gel based techniques. This review summarizes the most important gel-free and gel-based proteomics techniques and compares their advantages and drawbacks.
Bone Regeneration Using Gene-Activated Matrices.
D'Mello, Sheetal; Atluri, Keerthi; Geary, Sean M; Hong, Liu; Elangovan, Satheesh; Salem, Aliasger K
2017-01-01
Gene delivery to bone is a potential therapeutic strategy for directed, sustained, and regulated protein expression. Tissue engineering strategies for bone regeneration include delivery of proteins, genes (viral and non-viral-mediated delivery), and/or cells to the bone defect site. In addition, biomimetic scaffolds and scaffolds incorporating bone anabolic agents greatly enhance the bone repair process. Regional gene therapy has the potential of enhancing bone defect healing and bone regeneration by delivering osteogenic genes locally to the osseous lesions, thereby reducing systemic toxicity and the need for using supraphysiological dosages of therapeutic proteins. By implanting gene-activated matrices (GAMs), sustained gene expression and continuous osteogenic protein production in situ can be achieved in a way that stimulates osteogenesis and bone repair within osseous defects. Critical parameters substantially affecting the therapeutic efficacy of gene therapy include the choice of osteogenic transgene(s), selection of non-viral or viral vectors, the wound environment, and the selection of ex vivo and in vivo gene delivery strategies, such as GAMs. It is critical for gene therapy applications that clinically beneficial amounts of proteins are synthesized endogenously within and around the lesion in a sustained manner. It is therefore necessary that reliable and reproducible methods of gene delivery be developed and tested for their efficacy and safety before translating into clinical practice. Practical considerations such as the age, gender, and systemic health of patients and the nature of the disease process also need to be taken into account in order to personalize the treatments and progress towards developing a clinically applicable gene therapy for healing bone defects. This review discusses tissue engineering strategies to regenerate bone with specific focus on non-viral gene delivery systems.
ON THE STIFFNESS OF DEMINERALIZED DENTIN MATRICES
Ryou, Heonjune; Turco, Gianluca; Breschi, Lorenzo; Tay, Franklin R.; Pashley, David H.; Arola, Dwayne
2015-01-01
Resin bonding to dentin requires the use of self-etching primers or acid etching to decalcify the surface and expose a layer of collagen fibrils of the dentin matrix. Acid-etching reduces the stiffness of demineralized dentin from approximately 19 GPa to 1 MPa, requiring that it floats in water to prevent it from collapsing during bonding procedures. Several publications show that crosslinking agents like gluteraladehyde, carbodiimide or grape seed extract can stiffen collagen and improve resin-dentin bond strength. Objective The objective was to assess a new approach for evaluating the changes in stiffness of decalcified dentin by polar solvents and a collagen cross-linker. Methods Fully demineralized dentin beams and sections of etched coronal dentin were subjected to indentation loading using a cylindrical flat indenter in water, and after treatment with ethanol or ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC). The stiffness was measured as a function of strain and as a function of loading rate from 1 to 50 µm/sec. Results At a strain of 0.25% the elastic modulus of the fully demineralized dentin was approximately 0.20 MPa. It increased to over 0.90 MPa at strains of 1%. Exposure to ethanol caused an increase in elastic modulus of up to four times. Increasing the loading rate from 1 to 50 µm/sec caused an increase in the apparent modulus of up to three times in both water and ethanol. EDC treatment caused increases in the stiffness in fully demineralized samples and in acid-etched demineralized dentin surfaces in situ. Significance Changes in the mechanical behavior of demineralized collagen matrices can be measured effectively under hydration via indentation with cylindrical flat indenters. This approach can be used for quantifying the effects of bonding treatments on the properties of decalcified dentin after acid etching, as well as to follow the loss of stiffness over time due to enzymatic degradation. PMID:26747822
Systems of Differential Equations with Skew-Symmetric, Orthogonal Matrices
ERIC Educational Resources Information Center
Glaister, P.
2008-01-01
The solution of a system of linear, inhomogeneous differential equations is discussed. The particular class considered is where the coefficient matrix is skew-symmetric and orthogonal, and where the forcing terms are sinusoidal. More general matrices are also considered.
Separation of traces of metal ions from sodium matrices
NASA Technical Reports Server (NTRS)
Korkisch, J.; Orlandini, K. A.
1969-01-01
Method for isolating metal ion traces from sodium matrices consists of two extractions and an ion exchange step. Extraction is accomplished by using 2-thenoyltrifluoracetone and dithizone followed by cation exchange.
Spectral density of a Wishart model for nonsymmetric correlation matrices.
Vinayak
2013-10-01
The Wishart model for real symmetric correlation matrices is defined as W=AA^{t}, where matrix A is usually a rectangular Gaussian random matrix and A^{t} is the transpose of A. Analogously, for nonsymmetric correlation matrices, a model may be defined for two statistically equivalent but different matrices A and B as AB^{t}. The corresponding Wishart model, thus, is defined as C=AB^{t}BA^{t}. We study the spectral density of C for the case when A and B are not statistically independent. The ensemble average of such nonsymmetric matrices, therefore, does not simply vanishes to a null matrix. In this paper we derive a Pastur self-consistent equation which describes spectral density of C at large matrix dimension. We complement our analytic results with numerics.
Eigenvalue statistics for the sum of two complex Wishart matrices
NASA Astrophysics Data System (ADS)
Kumar, Santosh
2014-09-01
The sum of independent Wishart matrices, taken from distributions with unequal covariance matrices, plays a crucial role in multivariate statistics, and has applications in the fields of quantitative finance and telecommunication. However, analytical results concerning the corresponding eigenvalue statistics have remained unavailable, even for the sum of two Wishart matrices. This can be attributed to the complicated and rotationally noninvariant nature of the matrix distribution that makes extracting the information about eigenvalues a nontrivial task. Using a generalization of the Harish-Chandra-Itzykson-Zuber integral, we find exact solution to this problem for the complex Wishart case when one of the covariance matrices is proportional to the identity matrix, while the other is arbitrary. We derive exact and compact expressions for the joint probability density and marginal density of eigenvalues. The analytical results are compared with numerical simulations and we find perfect agreement.
Synbiotic matrices derived from plant oligosaccharides and polysaccharides
Technology Transfer Automated Retrieval System (TEKTRAN)
A porous synbiotic matrix was prepared by lyophilization of alginate and pectin or fructan oligosaccharides and polysaccharides cross-linked with calcium. These synbiotic matrices were excellent physical structures to support the growth of Lactobacillus acidophilus (1426) and Lactobacillus reuteri (...
Morphic images of binary words and Parikh matrices
NASA Astrophysics Data System (ADS)
Isawasan, Pradeep; Venkat, Ibrahim; Subramanian, K. G.; Sarmin, Nor Haniza
2014-07-01
A word is a finite sequence of symbols. Parikh matrix of a word, introduced by Mateescu et al (2000), has become an effective tool in the study of certain numerical properties of words based on subwords. There have been several investigations on various properties of Parikh matrices such as M-ambiguity, M-equivalence, subword equalities and inequalities, commutativity and so on. Recently, Parikh matrices of words that are images under certain morphisms have been studied for their properties. On the other hand, Parikh matrices of words involving a certain ratio property called weak-ratio property have been investigated by Subramanian et al (2009). Here we consider two special morphisms called Fibonacci and Tribonacci morphisms and obtain properties of Parikh matrices of images of binary words under these morphisms, utilizing the notion of weak-ratio property.
Joint Estimation of Multiple Precision Matrices with Common Structures
Lee, Wonyul; Liu, Yufeng
2015-01-01
Estimation of inverse covariance matrices, known as precision matrices, is important in various areas of statistical analysis. In this article, we consider estimation of multiple precision matrices sharing some common structures. In this setting, estimating each precision matrix separately can be suboptimal as it ignores potential common structures. This article proposes a new approach to parameterize each precision matrix as a sum of common and unique components and estimate multiple precision matrices in a constrained l1 minimization framework. We establish both estimation and selection consistency of the proposed estimator in the high dimensional setting. The proposed estimator achieves a faster convergence rate for the common structure in certain cases. Our numerical examples demonstrate that our new estimator can perform better than several existing methods in terms of the entropy loss and Frobenius loss. An application to a glioblastoma cancer data set reveals some interesting gene networks across multiple cancer subtypes. PMID:26568704
Performance Properties of Graphite Reinforced Composites with Advanced Resin Matrices
NASA Technical Reports Server (NTRS)
Kourtides, Demetrius A.
1980-01-01
This article looks at the effect of different resin matrices on thermal and mechanical properties of graphite composites, and relates the thermal and flammability properties to the anaerobic char yield of the resins. The processing parameters of graphite composites utilizing graphite fabric and epoxy or other advanced resins as matrices are presented. Thermoset resin matrices studied were: aminecured polyfunctional glycidyl aminetype epoxy (baseline), phenolicnovolac resin based on condensation of dihydroxymethyl-xylene and phenol cured with hexamine, two types of polydismaleimide resins, phenolic resin, and benzyl resin. The thermoplastic matrices studied were polyethersulfone and polyphenylenesulfone. Properties evaluated in the study included anaerobic char yield, limiting oxygen index, smoke evolution, moisture absorption, and mechanical properties at elevated temperatures including tensile, compressive, and short-beam shear strengths. Generally, it was determined that graphite composites with the highest char yield exhibited optimum fire-resistant properties.
Estimating soil matric potential in Owens Valley, California
Sorenson, Stephen K.; Miller, R.F.; Welch, M.R.; Groeneveld, D.P.; Branson, F.A.
1988-01-01
Much of the floor of the Owens Valley, California, is covered with alkaline scrub and alkaline meadow plant communities, whose existence is dependent partly on precipitation and partly on water infiltrated into the rooting zone from the shallow water table. The extent to which these plant communities are capable of adapting to and surviving fluctuations in the water table depends on physiological adaptations of the plants and on the water content, matric potential characteristics of the soils. Two methods were used to estimate soil matric potential in test sites in Owens Valley. The first was the filter-paper method, which uses water content of filter papers equilibrated to water content of soil samples taken with a hand auger. The other method of estimating soil matric potential was a modeling approach based on data from this and previous investigations. These data indicate that the base 10 logarithm of soil matric potential is a linear function of gravimetric soil water content for a particular soil. Estimates of soil water characteristic curves were made at two sites by averaging the gravimetric soil water content and soil matric potential values from multiple samples at 0.1 m depths derived by using the hand auger and filter paper method and entering these values in the soil water model. The characteristic curves then were used to estimate soil matric potential from estimates of volumetric soil water content derived from neutron-probe readings. Evaluation of the modeling technique at two study sites indicated that estimates of soil matric potential within 0.5 pF units of the soil matric potential value derived by using the filter paper method could be obtained 90 to 95% of the time in soils where water content was less than field capacity. The greatest errors occurred at depths where there was a distinct transition between soils of different textures. (Lantz-PTT)
Boundary transfer matrices and boundary quantum KZ equations
Vlaar, Bart
2015-07-15
A simple relation between inhomogeneous transfer matrices and boundary quantum Knizhnik-Zamolodchikov (KZ) equations is exhibited for quantum integrable systems with reflecting boundary conditions, analogous to an observation by Gaudin for periodic systems. Thus, the boundary quantum KZ equations receive a new motivation. We also derive the commutativity of Sklyanin’s boundary transfer matrices by merely imposing appropriate reflection equations, in particular without using the conditions of crossing symmetry and unitarity of the R-matrix.
In vitro characterization of polycaprolactone matrices generated in aqueous media.
Pok, Seok Won; Wallace, Kristin N; Madihally, Sundararajan V
2010-03-01
In this study, a novel process of dissolving polycaprolactone (PCL) matrices in glacial acetic acid was explored in which matrices spontaneously formed upon contact with water. Scanning electron microscopy analysis showed rough architecture and holes on the self-assembled matrix relative to matrices formed after dissolving in chloroform. Immersion in the gelatin solution reduced its roughness and number of micropores. Atomic force microscopy (AFM) analysis confirmed the increased roughness of the self-assembled matrices. The roughness of the matrices decreased after incubation in 1N NaOH for 10 min. AFM analysis also revealed that the self-assembled matrix had a net positive surface charge, whereas chloroform-cast matrix had a negative surface charge. The surface charge of self-assembled matrix after immersion in gelatin changed to negative. However, incubation in NaOH did not affect the surface charge. The tensile properties were tested in both the dry state (25 degrees Celsius) and the wet state (37 degrees Celsius) by immersion in phosphate-buffered saline. Self-assembled matrix had lower elastic modulus, break stress and break strain than chloroform-cast matrix in both states. The elastic modulus in the wet condition was reduced by half in self-assembled matrix but tensile strain increased. Samples were further analyzed by ramp-hold test for assessing stress relaxation behavior. Both self-assembled and chloroform-cast matrices had similar trends in stress relaxation behavior. However, stress accumulation in self-assembled matrix was half that of chloroform-cast matrix. In vitro cell cultures were conducted using human foreskin fibroblast (HFF-1) in serum-free medium. Cytoskeletal actin staining showed cell adhesion and spreading on all matrices. Cell retention was significantly increased in self-assembled matrix compared to chloroform-cast matrix. Addition of gelatin improved the retention of seeded cells on the surface. In summary, PCL matrices generated using
Preliminary Analysis on Matric Suction for Barren Soil
NASA Astrophysics Data System (ADS)
Azhar, A. T. S.; Fazlina, M. I. S.; Aziman, M.; Fairus, Y. M.; Azman, K.; Hazreek, Z. A. M.
2016-11-01
Most research conducted on slope failures can broadly be attributed to the convergence of three factors, i.e. rainfall, steepness of slope, and soil geological profile. The mechanism of the failures is mainly due to the loss of matric suction of soils by rainwater. When rainwater infiltrates into the slopes, it will start to saturate the soil, i.e., reduce the matric suction. A good understanding of landslide mechanisms and the characteristics of unsaturated soil and rock in tropical areas is crucial in landslide hazard formulation. Most of the slope failures in unsaturated tropical residual soil in Malaysia are mainly due to infiltration, especially during intense and prolonged rainfall, which reduces the soil matric suction and hence decreases the stability of the slope. Therefore, the aim of this research is to determine the matric suction for barren soil and to model an unsaturated slope with natural rainfall to evaluate the effects of matric suction on rainfall intensity. A field test was carried out using the Watermark Soil Moisture Sensor to determine the matric suction. The sensor was connected to a program called SpecWare 9 Basic which also used Data Logging Rain gauge Watermark 1120 to measure the intensity and duration of rainfall. This study was conducted at the Research Centre for Soft Soil which is a new Research and Development (R & D) initiative by Universiti Tun Hussein Onn Malaysia, Parit Raja. Field observation showed that the highest daily suction was recorded during noon while the lowest suction was obtained at night and early morning. The highest matric suction for loose condition was 31.0 kPa while the highest matric suction for compacted condition was 32.4 kPa. The results implied that the field suction variation was not only governed by the rainfall, but also the cyclic evaporation process. The findings clearly indicated that the changes in soil suction distribution patterns occurred due to different weather conditions.
Sethi, Sneha
2014-01-01
Background: Autocrine motility factor receptor (AMFR) is a tumour motility stimulating protein secreted by tumour cells. The protein encoded by this gene is a glycosylated transmembrane protein and a receptor for autocrine motility factor. It has been known to play a role in progression of neoplastic lesions. Basement membranes are specialized extracellular matrices that serve as structural barriers as well as substrates for cellular interactions. The network of type IV collagen is thought to define the scaffold integrating other components such as laminins and perlecan into highly organized supramolecular architecture. The aim of this study was to determine and evaluate the immunohistochemical expression of Type IV Collagen and Autocrine motility factor receptor in odontogenic lesions. Materials and Methods: Immunohistochemical expression of Type IV Collagen and Autocrine motility factor receptor was evaluated in 31 odontogenic lesions, including unicystic ameloblastoma, multicystic ameloblastoma, keratocystic odontogenic tumour and ameloblastic carcinoma. Normal follicular tissue formed the control. Results: Maximum expression for Type IV Collagen was seen in multicystic ameloblastoma and minimum expression in keratocystic odontogenic tumour. The maximum expression of AMFR was seen in ameloblastic carcinoma and minimum expression in multicystic ameloblastoma. Conclusion: The results of this study suggested an association of loss of expression of type IV Collagen with progression of lesion. AMFR expression was found to be associated with the aggressive potential of tumours. PMID:25478440
Bleach gel: a simple agarose gel for analyzing RNA quality.
Aranda, Patrick S; LaJoie, Dollie M; Jorcyk, Cheryl L
2012-01-01
RNA-based applications requiring high-quality, non-degraded RNA are a foundational element of many research studies. As such, it is paramount that the integrity of experimental RNA is validated prior to cDNA synthesis or other downstream applications. In the absence of expensive equipment such as microfluidic electrophoretic devices, and as an alternative to the costly and time-consuming standard formaldehyde gel, RNA quality can be quickly analyzed by adding small amounts of commercial bleach to TAE buffer-based agarose gels prior to electrophoresis. In the presence of low concentrations of bleach, the secondary structure of RNA is denatured and potential contaminating RNases are destroyed. Because of this, the 'bleach gel' is a functional approach that addresses the need for an inexpensive and safe way to evaluate RNA integrity and will improve the ability of researchers to rapidly analyze RNA quality.
Inference for High-dimensional Differential Correlation Matrices *
Cai, T. Tony; Zhang, Anru
2015-01-01
Motivated by differential co-expression analysis in genomics, we consider in this paper estimation and testing of high-dimensional differential correlation matrices. An adaptive thresholding procedure is introduced and theoretical guarantees are given. Minimax rate of convergence is established and the proposed estimator is shown to be adaptively rate-optimal over collections of paired correlation matrices with approximately sparse differences. Simulation results show that the procedure significantly outperforms two other natural methods that are based on separate estimation of the individual correlation matrices. The procedure is also illustrated through an analysis of a breast cancer dataset, which provides evidence at the gene co-expression level that several genes, of which a subset has been previously verified, are associated with the breast cancer. Hypothesis testing on the differential correlation matrices is also considered. A test, which is particularly well suited for testing against sparse alternatives, is introduced. In addition, other related problems, including estimation of a single sparse correlation matrix, estimation of the differential covariance matrices, and estimation of the differential cross-correlation matrices, are also discussed. PMID:26500380
Inference for High-dimensional Differential Correlation Matrices.
Cai, T Tony; Zhang, Anru
2016-01-01
Motivated by differential co-expression analysis in genomics, we consider in this paper estimation and testing of high-dimensional differential correlation matrices. An adaptive thresholding procedure is introduced and theoretical guarantees are given. Minimax rate of convergence is established and the proposed estimator is shown to be adaptively rate-optimal over collections of paired correlation matrices with approximately sparse differences. Simulation results show that the procedure significantly outperforms two other natural methods that are based on separate estimation of the individual correlation matrices. The procedure is also illustrated through an analysis of a breast cancer dataset, which provides evidence at the gene co-expression level that several genes, of which a subset has been previously verified, are associated with the breast cancer. Hypothesis testing on the differential correlation matrices is also considered. A test, which is particularly well suited for testing against sparse alternatives, is introduced. In addition, other related problems, including estimation of a single sparse correlation matrix, estimation of the differential covariance matrices, and estimation of the differential cross-correlation matrices, are also discussed.
Action recognition from video using feature covariance matrices.
Guo, Kai; Ishwar, Prakash; Konrad, Janusz
2013-06-01
We propose a general framework for fast and accurate recognition of actions in video using empirical covariance matrices of features. A dense set of spatio-temporal feature vectors are computed from video to provide a localized description of the action, and subsequently aggregated in an empirical covariance matrix to compactly represent the action. Two supervised learning methods for action recognition are developed using feature covariance matrices. Common to both methods is the transformation of the classification problem in the closed convex cone of covariance matrices into an equivalent problem in the vector space of symmetric matrices via the matrix logarithm. The first method applies nearest-neighbor classification using a suitable Riemannian metric for covariance matrices. The second method approximates the logarithm of a query covariance matrix by a sparse linear combination of the logarithms of training covariance matrices. The action label is then determined from the sparse coefficients. Both methods achieve state-of-the-art classification performance on several datasets, and are robust to action variability, viewpoint changes, and low object resolution. The proposed framework is conceptually simple and has low storage and computational requirements making it attractive for real-time implementation.
Thixotropic gel for vadose zone remediation
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.
Thixotropic gel for vadose zone remediation
Rhia, Brian D [Augusta, GA
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.
Thixotropic gel for vadose zone remediation
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.
User`s guide and documentation manual for ``PC-Gel`` simulator
Chang, Ming-Ming; Gao, Hong W.
1993-10-01
PC-GEL is a three-dimensional, three-phase (oil, water, and gas) permeability modification simulator developed by incorporating an in-situ gelation model into a black oil simulator (BOAST) for personal computer application. The features included in the simulator are: transport of each chemical species of the polymer/crosslinker system in porous media, gelation reaction kinetics of the polymer with crosslinking agents, rheology of the polymer and gel, inaccessible pore volume to macromolecules, adsorption of chemical species on rock surfaces, retention of gel on the rock matrix, and permeability reduction caused by the adsorption of polymer and gel. The in-situ gelation model and simulator were validated against data reported in the literature. The simulator PC-GEL is useful for simulating and optimizing any combination of primary production, waterflooding, polymer flooding, and permeability modification treatments. A general background of permeability modification using crosslinked polymer gels is given in Section I and the governing equations, mechanisms, and numerical solutions of PC-GEL are given in Section II. Steps for preparing an input data file with reservoir and gel-chemical transport data, and recurrent data are described in Sections III and IV, respectively. Example data inputs are enclosed after explanations of each input line to help the user prepare data files. Major items of the output files are reviewed in Section V. Finally, three sample problems for running PC-GEL are described in Section VI, and input files and part of the output files of these problems are listed in the appendices. For the user`s reference a copy of the source code of PC-GEL computer program is attached in Appendix A.
Code of Federal Regulations, 2010 CFR
2010-04-01
... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Schedule IV. 1308.14 Section 1308.14 Food and Drugs DRUG ENFORCEMENT ADMINISTRATION, DEPARTMENT OF JUSTICE SCHEDULES OF CONTROLLED SUBSTANCES Schedules § 1308.14 Schedule IV. (a) Schedule IV shall consist of the drugs and other substances,...
2009-01-01
September 2009 Recommended by Enrico Capobianco This paper considers the lower and upper bounds of eigenvalues of arrow-head matrices. We propose a... Fermi liquid [2]. Numerically efficient algorithms for computing eigenvalues and eigenvectors of arrowhead matrices were discussed in [3]. The...tions,” The Journal of Chemical Physics, vol. 48, no. 2, pp. 715– 726, 1968. [2] J. W. Gadzuk, “Localized vibrational modes in Fermi liquids. General
Crystalline Colloidal Arrays in Polymer Matrices
NASA Technical Reports Server (NTRS)
Sunkara, Hari B.; Penn, B. G.; Frazier, D. O.; Ramachandran, N.
1997-01-01
matrices, the factors which affect the optical diffraction qualities of resulting polymer films, and methods to improve the efficiencies of solid optical filters. Before this, we also present the experimental demonstration, of controlling the optical diffraction intensities from aqueous CCA dispersions by varying the temperature, which establishes the feasibility of fabricating all-optical switching devices with nonlinear periodic array structures.
Estimated correlation matrices and portfolio optimization
NASA Astrophysics Data System (ADS)
Pafka, Szilárd; Kondor, Imre
2004-11-01
Correlations of returns on various assets play a central role in financial theory and also in many practical applications. From a theoretical point of view, the main interest lies in the proper description of the structure and dynamics of correlations, whereas for the practitioner the emphasis is on the ability of the models to provide adequate inputs for the numerous portfolio and risk management procedures used in the financial industry. The theory of portfolios, initiated by Markowitz, has suffered from the “curse of dimensions” from the very outset. Over the past decades a large number of different techniques have been developed to tackle this problem and reduce the effective dimension of large bank portfolios, but the efficiency and reliability of these procedures are extremely hard to assess or compare. In this paper, we propose a model (simulation)-based approach which can be used for the systematical testing of all these dimensional reduction techniques. To illustrate the usefulness of our framework, we develop several toy models that display some of the main characteristic features of empirical correlations and generate artificial time series from them. Then, we regard these time series as empirical data and reconstruct the corresponding correlation matrices which will inevitably contain a certain amount of noise, due to the finiteness of the time series. Next, we apply several correlation matrix estimators and dimension reduction techniques introduced in the literature and/or applied in practice. As in our artificial world the only source of error is the finite length of the time series and, in addition, the “true” model, hence also the “true” correlation matrix, are precisely known, therefore in sharp contrast with empirical studies, we can precisely compare the performance of the various noise reduction techniques. One of our recurrent observations is that the recently introduced filtering technique based on random matrix theory performs
Michailova, V; Titeva, S; Kotsilkova, R; Krusteva, E; Minkov, E
2001-07-03
The kinetics of water penetration and molsidomine release from both hydroxypropylmethyl cellulose (HPMC) and mixed HPMC/thermally pregelatinized waxy maize starch (SDWMT) hydrophilic matrices has been examined in 0.1 mol x dm(-3) HCl (pH 1.0) and 0.06 mol x dm(-3) Na3PO4/HCl buffer (pH 6.8). The rheological oscillatory test parameters of their gel layers obtained by swelling of the matrices in the two aqueous media have been observed. The kinetic swelling properties of mixed HPMC/SDWMT hydrogels (i.e. degree and velocity of both water penetration and swelling, transport mechanism which controls solvent sorption) directly influence the drug release behaviour and the structural features of the formed gel layer. Both diffusion processes are diffusion-controlled ones, their mechanisms being influenced insignificantly by the relaxation properties of the hydrated macromolecules. It has been established by means of comparative viscoelastic analysis, that mixed HPMC/SDWMT hydrogels demonstrate the typical behaviour of 'filled' composite systems having poor adhesion between the surface of the elastic SDWMT 'filler' and the continuous HPMC phase. Due to the inter-phase relations between the swollen starch granules and the linear cellulose derivative as well as to the specific structure of amylopectin molecule, the pregelatinized waxy maize starch shows a stronger influence on the velocities of both water penetration and drug release from mixed HPMC/SDWMT matrices.
Deformation of Unentangled Swollen Gels
NASA Astrophysics Data System (ADS)
Sariyer, Ozan; Panyukov, Sergey; Rubinstein, Michael
2014-03-01
We study the deformation characteristics (Poisson's ratios and stress-strain relations) of unentangled gels swollen and uniaxially or biaxially deformed in excess solvent by considering the balance of osmotic pressure and elastic stress in unconstrained dimensions. Our scaling theory predicts a crossover from theta solvent behavior to marginal solvent behavior upon stretching gels that are in concentrated regime at swelling equilibrium - a phenomenon that was experimentally observed long ago, but not understood theoretically. For gels that are in the semidilute good solvent regime at swelling equilibrium, we predict a crossover to theta solvent behavior upon compression and a crossover to marginal solvent behavior upon stretching. Our theory reproduces the previously known results for equilibrium swelling degree as well as known deformation characteristics in theta and athermal solvents.
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.
Copolymers For Capillary Gel Electrophoresis
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.
An inexpensive microslab gel DNA electrophoresis system with real-time fluorescence detection.
Chen, Xiaojia; Ugaz, Victor M
2006-02-01
In this paper, we describe the construction of a simple yet powerful gel electrophoresis apparatus that can be used to perform size-selective separations of DNA fragments in virtually any laboratory. This system employs a microslab gel format with a novel gel casting technique that eliminates the need for delicate combs to define sample loading wells. The compact size of the microslab gel format allows rapid separations to be performed at low voltages using submicroliter sample volumes. Real time fluorescence detection of the migrating DNA fragments is accomplished using an inexpensive digital microscope that directly connects to any PC with a USB interface. The microscope is readily adaptable for this application by replacing its white light source with a blue light-emitting diode (LED) and adding an appropriate emission filter. Both polyacrylamide and agarose gels can be used as separation matrices. Separation performance was characterized using standard dsDNA ladders, and correct sizing of a 191 bp PCR product was achieved in 15 min. The low cost and simplicity of this system makes it ideally suited for use in a variety of laboratory and educational settings.
Soft fibrin gels promote selection and growth of tumorigenic cells
NASA Astrophysics Data System (ADS)
Liu, Jing; Tan, Youhua; Zhang, Huafeng; Zhang, Yi; Xu, Pingwei; Chen, Junwei; Poh, Yeh-Chuin; Tang, Ke; Wang, Ning; Huang, Bo
2012-08-01
The identification of stem-cell-like cancer cells through conventional methods that depend on stem cell markers is often unreliable. We developed a mechanical method for selecting tumorigenic cells by culturing single cancer cells in fibrin matrices of ~100 Pa in stiffness. When cultured within these gels, primary human cancer cells or single cancer cells from mouse or human cancer cell lines grew within a few days into individual round colonies that resembled embryonic stem cell colonies. Subcutaneous or intravenous injection of 10 or 100 fibrin-cultured cells in syngeneic or severe combined immunodeficiency mice led to the formation of solid tumours at the site of injection or at the distant lung organ much more efficiently than control cancer cells selected using conventional surface marker methods or cultured on conventional rigid dishes or on soft gels. Remarkably, as few as ten such cells were able to survive and form tumours in the lungs of wild-type non-syngeneic mice.
Test Review: Advanced Clinical Solutions for WAIS-IV and WMS-IV
ERIC Educational Resources Information Center
Chu, Yiting; Lai, Mark H. C.; Xu, Yining; Zhou, Yuanyuan
2012-01-01
The authors review the "Advanced Clinical Solutions for WAIS-IV and WMS-IV". The "Advanced Clinical Solutions (ACS) for the Wechsler Adult Intelligence Scale-Fourth Edition" (WAIS-IV; Wechsler, 2008) and the "Wechsler Memory Scale-Fourth Edition" (WMS-IV; Wechsler, 2009) was published by Pearson in 2009. It is a…
Oxovanadium(IV) silsesquioxane complexes.
Ohde, Christian; Limberg, Christian; Stösser, Reinhard; Demeshko, Serhiy
2010-03-01
In the context of a potential modeling of reduced oxovanadium species occurring on the surfaces of silica-supported vanadia catalysts in the course of its turnover, the incompletely condensed silsesquioxane H(3)(c-pentyl)T(7) was reacted with Cl(4)V(THF)(2) (where THF = tetrahydrofuran) in the presence of triethylamine. Precipitation of 3 equiv of HNEt(3)Cl seemed to point to the clean formation of [((c-pentyl)T(7))(V(IV)Cl)] (1), which was supported by electron paramagnetic resonance studies performed for the resulting solutions, but further analytical and spectroscopic investigations showed that the processes occurring at that stage are more complex than that and even include the formation of [((c-pentyl)T(7))(V(V)O)](2) as a side product. Storage of a red-brown hexane solution of this product mixture reproducibly led to the precipitation of blue crystals belonging to the chloride-free compound [((c-pentyl)T(7))(2)(V(IV)=O)(3)(THF)(2)] (2), as revealed by single-crystal X-ray diffraction. Performing the same reaction in the presence of 2 equiv of pyridine leads to an analogous product, where the THF ligands are replaced by pyridine. Subsequent investigations showed that the terminal oxo ligands at the vanadium centers are, on the one hand, due to the presence of adventitious water; on the other hand, the [(c-pentyl)T(7)](3-) ligand also acted as a source of O(2-). The results of SQUID measurements performed for 2 can be interpreted in terms of a ferromagnetic coupling between the vanadyl units. Exposing 2 to a dioxygen atmosphere resulted in its immediate oxidation to yield the V(V) complex [((c-pentyl)T(7))(V(V)O)](2), which may model a fast reoxidation reaction of oxovanadium(IV) trimers on silica surfaces.
Ji, Xiaofan; Shi, Bingbing; Wang, Hu; Xia, Danyu; Jie, Kecheng; Wu, Zi Liang; Huang, Feihe
2015-12-22
Multifluorescent supramolecular gels with complex structures are constructed from discrete fluorescent gels, which serve as the building blocks, through hydrogen bonding interactions at interfaces. The multifluorescent gel can realize rapid healing within only ≈100 s.
Microbubble tunneling in gel phantoms
Caskey, Charles F.; Qin, Shengping; Dayton, Paul A.; Ferrara, Katherine W.
2009-01-01
Insonified microbubbles were observed in vessels within a gel with a Young’s modulus similar to that of tissue, demonstrating shape instabilities, liquid jets, and the formation of small tunnels. In this study, tunnel formulation occurred in the direction of the propagating ultrasound wave, where radiation pressure directed the contact of the bubble and gel, facilitating the activity of the liquid jets. Combinations of ultrasonic parameters and microbubble concentrations that are relevant for diagnostic imaging and drug delivery and that lead to tunnel formation were applied and the resulting tunnel formation was quantified. PMID:19425620
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
Exploratory and hierarchical factor analysis of the WJ-IV Cognitive at school age.
Dombrowski, Stefan C; McGill, Ryan J; Canivez, Gary L
2017-04-01
Exploratory and confirmatory factor analytic studies were not reported in the Technical Manual for the Woodcock-Johnson, 4th ed. Cognitive (WJ IV Cognitive; Schrank, McGrew, & Mather, 2014b) Instead, the internal structure of the WJ IV Cognitive was extrapolated from analyses based on the full WJ IV test battery (Schrank, McGrew, & Mather, 2014b). Even if the veracity of extrapolating from the WJ IV full battery were accepted, there were shortcomings in the choices of analyses used and only limited information regarding those analyses was presented in the WJ IV Technical Manual (McGrew, Laforte, & Shrank, 2014). The present study examined the structure of the WJ IV Cognitive using exploratory factor analysis procedures (principal axis factoring with oblique [promax] rotation followed by application of the Schmid-Leiman, 1957, procedure) applied to standardization sample correlation matrices for 2 school age groups (ages 9-13; 14-19). Four factors emerged for both the 9-13 and 14-19 age groups in contrast to the publisher's proposed 7 factors. Results of these analyses indicated a robust manifestation of general intelligence (g) that exceeded the variance attributed to the lower-order factors. Model-based reliability estimates supported interpretation of the higher-order factor (i.e., g). Additional analyses were conducted by forcing extraction of the 7 theoretically posited factors; however, the resulting solution was only partially aligned (i.e., Gs, Gwm) with the theoretical structure promoted in the Technical Manual and suggested the preeminence of the higher-order factor. Results challenge the hypothesized structure of the WJ IV Cognitive and raise concerns about its alignment with Cattell-Horn-Carroll theory. (PsycINFO Database Record
PREPARATION OF OXOPORPHINATOMANGANESE (IV) COMPLEX
Willner, I.; Otvos, J.; Calvin, M.
1980-07-01
Oxo-manganese-tetraphenylporphyrin (O=Mn{sup IV}-TPP) has been prepared by an oxygen-transfer reaction from iodosylbenzene to MnIITPP and characterized by its i.r. and field desorption mass spectra, which are identical to those of the product obtained by direct oxidation of Mn{sup III}(TPP) in an aqueous medium; it transfers oxygen to triphenylphosphine to produce triphenylphosphine oxide, and it is suggested that similar intermediates are important in oxygen activation by cytochrome P-450 as well as in the photosynthetic evolution of oxygen.
Immobilization of chromium in cement matrices
Kindness, A.; Macias, A.; Glasser, F.P. . Dept. of Chemistry)
1994-01-01
Portland cement and blended cements containing blast furnace slag afford both physical and chemical immobilization of chromium. To separate physical and chemical effects, the pore fluid contained in set, hydrated cements has been expressed and analyzed. In Portland cement spiked with 5,000 ppm Cr(III), pore fluid levels are 0.1--1 ppm, whereas in well-cured slag blends, they decrease to <0.01 ppm. Both cement types give chemical immobilization, but slag cements give the better performance. Slag-containing cements are the most effective at removing Cr(VI) from the pore fluid, probably by reducing Cr(VI) to Cr(III). Electron microscopy coupled with energy dispersive X-ray analysis shows that Cr(III) can be substituted for Al in most of the calcium aluminated hydrate phases. In synthetic preparations, substitution is complete resulting in Ca-Cr phases that are isostructural to calcium aluminate phases. Three Cr analogues of calcium aluminates were synthesized: Ca[sub 2]Cr(OH)[sub 7] [center dot] 3H[sub 2]O, Ca[sub 2]Cr[sub 2]O[sub 5] [center dot] 6H[sub 2]O and Ca[sub 2]Cr[sub 2]O[sub 5] [center dot] 8H[sub 2]O, as well as solid solutions, e.g., Cr substituted hydrogarnet 3CaO [center dot] (Al[sub 2]O[sub 3]/Cr[sub 2]O[sub 3]) [center dot] 6H[sub 2]O. There is no real evidence that Cr is taken up by C-S-H gel.
Clinical presentations of Ehlers Danlos syndrome type IV.
Pope, F M; Narcisi, P; Nicholls, A C; Liberman, M; Oorthuys, J W
1988-01-01
Ehlers Danlos syndrome type IV is an often lethal disease caused by various mutations of type III collagen genes. It presents in infancy and childhood in several ways, and the symptoms and signs include low birth weight, prematurity, congenital dislocation of the hips, easy inappropriate bruising (sometimes suspected as child battering), and a diagnostic facial phenotype. These features predict a lethal adult disease often complicated by fatal arterial rupture in early or middle adult life. Most affected patients can be diagnosed from radiolabelled collagen protein profiles by polyacrylamide gel electrophoresis. Prenatal diagnosis by specific type III collagen restriction fragment length polymorphisms is possible in some families, and will become increasingly important. Prenatal diagnosis and prevention of the disease in selected families is already possible and will be widely available in the future. Images Fig 1 Fig 2 Fig 3 Fig 4 Fig 5 Fig 6 Fig 7 Fig 8 Fig 9 Fig 10 Fig 11 PMID:3178263
Randomized Algorithms for Matrices and Data
NASA Astrophysics Data System (ADS)
Mahoney, Michael W.
2012-03-01
This chapter reviews recent work on randomized matrix algorithms. By “randomized matrix algorithms,” we refer to a class of recently developed random sampling and random projection algorithms for ubiquitous linear algebra problems such as least-squares (LS) regression and low-rank matrix approximation. These developments have been driven by applications in large-scale data analysis—applications which place very different demands on matrices than traditional scientific computing applications. Thus, in this review, we will focus on highlighting the simplicity and generality of several core ideas that underlie the usefulness of these randomized algorithms in scientific applications such as genetics (where these algorithms have already been applied) and astronomy (where, hopefully, in part due to this review they will soon be applied). The work we will review here had its origins within theoretical computer science (TCS). An important feature in the use of randomized algorithms in TCS more generally is that one must identify and then algorithmically deal with relevant “nonuniformity structure” in the data. For the randomized matrix algorithms to be reviewed here and that have proven useful recently in numerical linear algebra (NLA) and large-scale data analysis applications, the relevant nonuniformity structure is defined by the so-called statistical leverage scores. Defined more precisely below, these leverage scores are basically the diagonal elements of the projection matrix onto the dominant part of the spectrum of the input matrix. As such, they have a long history in statistical data analysis, where they have been used for outlier detection in regression diagnostics. More generally, these scores often have a very natural interpretation in terms of the data and processes generating the data. For example, they can be interpreted in terms of the leverage or influence that a given data point has on, say, the best low-rank matrix approximation; and this
Estimating soil matric potential in Owens Valley, California
Sorenson, Stephen K.; Miller, Reuben F.; Welch, Michael R.; Groeneveld, David P.; Branson, Farrel A.
1989-01-01
Much of the floor of Owens Valley, California, is covered with alkaline scrub and alkaline meadow plant communities, whose existence is dependent partly on precipitation and partly on water infiltrated into the rooting zone from the shallow water table. The extent to which these plant communities are capable of adapting to and surviving fluctuations in the water table depends on physiological adaptations of the plants and on the water content, matric potential characteristics of the soils. Two methods were used to estimate soil matric potential in test sites in Owens Valley. The first, the filter-paper method, uses water content of filter papers equilibrated to water content of soil samples taken with a hand auger. The previously published calibration relations used to estimate soil matric potential from the water content of the filter papers were modified on the basis of current laboratory data. The other method of estimating soil matric potential was a modeling approach based on data from this and previous investigations. These data indicate that the base-10 logarithm of soil matric potential is a linear function of gravimetric soil water content for a particular soil. The slope and intercepts of this function vary with the texture and saturation capacity of the soil. Estimates of soil water characteristic curves were made at two sites by averaging the gravimetric soil water content and soil matric potential values from multiple samples at 0.1-m depth intervals derived by using the hand auger and filter-paper method and entering these values in the soil water model. The characteristic curves then were used to estimate soil matric potential from estimates of volumetric soil water content derived from neutron-probe readings. Evaluation of the modeling technique at two study sites indicated that estimates of soil matric potential within 0.5 pF units of the soil matric potential value derived by using the filter-paper method could be obtained 90 to 95 percent of the
Hoshiba, Takashi; Kawazoe, Naoki; Tateishi, Tetsuya; Chen, Guoping
2009-01-01
An extracellular microenvironment, including an extracellular matrix (ECM), is an important factor in regulating stem cell differentiation. During tissue development, the ECM is dynamically remodeled to regulate stem cell functions. Here, we developed matrices mimicking ECM remodeling during the osteogenesis of mesenchymal stem cells (MSCs). The matrices were prepared from cultured MSCs controlled at different stages of osteogenesis and referred to as “stepwise osteogenesis-mimicking matrices.” The matrices supported the adhesion and proliferation of MSCs and showed different effects on the osteogenesis of MSCs. On the matrices mimicking the early stage of osteogenesis (early stage matrices), the osteogenesis occurred more rapidly than did that on the matrices mimicking undifferentiated stem cells (stem cell matrices) and the late stage of osteogenesis (late stage matrices). RUNX2 was similarly expressed when MSCs were cultured on both the early stage and late stage matrices but decreased on the stem cell matrices. PPARG expression in the MSCs cultured on the late stage matrices was higher than for those cultured on the stem cell and early stage matrices. This increase of PPARG expression was caused by the suppression of the amount of β-catenin and downstream signal transduction. These results demonstrate that the osteogenesis-mimicking matrices had different effects on the osteogenesis of MSCs, and the early stage matrices provided a favorable microenvironment for the osteogenesis. PMID:19762920
Null matrices and the analysis of species co-occurrences.
Sanderson, James G; Moulton, Michael P; Selfridge, Ralph G
1998-08-01
Patterns in species occurrences on islands have been analyzed by several authors. At issue is the number of non-occurring pairs of species (also known as checkerboards). Previous authors have suggested that if the number of checkerboards differs from what is expected by chance, then island communities might have been structured by competition. Investigators have pursued this problem by first generating random (or null) matrices and then testing a metric derived from the collection of null matrices against the metric calculated from the actual species co-occurrence matrix. The random matrices were constrained by requiring the number of species on each island, and the number of islands on which each species occurred to be equal to their observed values. We show that results from previous studies are generally flawed. We present a fast, efficient algorithm to generate null matrices for any set of fixed row and column sums, and propose a modification of a previously proposed metric as a test statistic. We evaluated the efficacy of our construction method for null creation and our metric using incidence matrices from the avifauna of Vanuatu (formerly New Hebrides).
Calibration and temperature correction of heat dissipation matric potential sensors
Flint, A.L.; Campbell, G.S.; Ellett, K.M.; Calissendorff, C.
2002-01-01
This paper describes how heat dissipation sensors, used to measure soil water matric potential, were analyzed to develop a normalized calibration equation and a temperature correction method. Inference of soil matric potential depends on a correlation between the variable thermal conductance of the sensor's porous ceramic and matric poten-tial. Although this correlation varies among sensors, we demonstrate a normalizing procedure that produces a single calibration relationship. Using sensors from three sources and different calibration methods, the normalized calibration resulted in a mean absolute error of 23% over a matric potential range of -0.01 to -35 MPa. Because the thermal conductivity of variably saturated porous media is temperature dependent, a temperature correction is required for application of heat dissipation sensors in field soils. A temperature correction procedure is outlined that reduces temperature dependent errors by 10 times, which reduces the matric potential measurement errors by more than 30%. The temperature dependence is well described by a thermal conductivity model that allows for the correction of measurements at any temperature to measurements at the calibration temperature.
Learning Discriminative Stein Kernel for SPD Matrices and Its Applications.
Zhang, Jianjia; Wang, Lei; Zhou, Luping; Li, Wanqing
2016-05-01
Stein kernel (SK) has recently shown promising performance on classifying images represented by symmetric positive definite (SPD) matrices. It evaluates the similarity between two SPD matrices through their eigenvalues. In this paper, we argue that directly using the original eigenvalues may be problematic because: 1) eigenvalue estimation becomes biased when the number of samples is inadequate, which may lead to unreliable kernel evaluation, and 2) more importantly, eigenvalues reflect only the property of an individual SPD matrix. They are not necessarily optimal for computing SK when the goal is to discriminate different classes of SPD matrices. To address the two issues, we propose a discriminative SK (DSK), in which an extra parameter vector is defined to adjust the eigenvalues of input SPD matrices. The optimal parameter values are sought by optimizing a proxy of classification performance. To show the generality of the proposed method, three kernel learning criteria that are commonly used in the literature are employed as a proxy. A comprehensive experimental study is conducted on a variety of image classification tasks to compare the proposed DSK with the original SK and other methods for evaluating the similarity between SPD matrices. The results demonstrate that the DSK can attain greater discrimination and better align with classification tasks by altering the eigenvalues. This makes it produce higher classification performance than the original SK and other commonly used methods.
Osteocalcin/fibronectin-functionalized collagen matrices for bone tissue engineering.
Kim, S G; Lee, D S; Lee, S; Jang, J-H
2015-06-01
Collagen is the most abundant protein found in the extracellular matrix and is widely used to build scaffolds for biomedical applications which are the result of its biocompatibility and biodegradability. In the present study, we constructed a rhOCN/FNIII9-10 fusion protein and rhOCN/FNIII9-10-functionalized collagen matrices and investigated the potential value for bone tissue engineering. In vitro studies carried out with preosteoblastic MC3T3-E1 cells showed that rhOCN/FNIII9-10 fusion protein promoted cell adhesion and the mRNA levels of osteogenic markers including osteocalcin, runt-related transcription factor 2, alkaline phosphatase (ALP), and collagen type I. In addition, rhOCN/FNIII9-10-functionalized collagen matrices showed significant induction of the ALP activity more than rhFNIII9-10-functionalized collagen matrices or collagen matrices alone. These results suggested that rhOCN/FNIII9-10-functionalized collagen matrices have potential for bone tissue engineering.
Laplacian matrices of weighted digraphs represented as quantum states
NASA Astrophysics Data System (ADS)
Adhikari, Bibhas; Banerjee, Subhashish; Adhikari, Satyabrata; Kumar, Atul
2017-03-01
Representing graphs as quantum states is becoming an increasingly important approach to study entanglement of mixed states, alternate to the standard linear algebraic density matrix-based approach of study. In this paper, we propose a general weighted directed graph framework for investigating properties of a large class of quantum states which are defined by three types of Laplacian matrices associated with such graphs. We generalize the standard framework of defining density matrices from simple connected graphs to density matrices using both combinatorial and signless Laplacian matrices associated with weighted directed graphs with complex edge weights and with/without self-loops. We also introduce a new notion of Laplacian matrix, which we call signed Laplacian matrix associated with such graphs. We produce necessary and/or sufficient conditions for such graphs to correspond to pure and mixed quantum states. Using these criteria, we finally determine the graphs whose corresponding density matrices represent entangled pure states which are well known and important for quantum computation applications. We observe that all these entangled pure states share a common combinatorial structure.
Efficient computer algebra algorithms for polynomial matrices in control design
NASA Technical Reports Server (NTRS)
Baras, J. S.; Macenany, D. C.; Munach, R.
1989-01-01
The theory of polynomial matrices plays a key role in the design and analysis of multi-input multi-output control and communications systems using frequency domain methods. Examples include coprime factorizations of transfer functions, cannonical realizations from matrix fraction descriptions, and the transfer function design of feedback compensators. Typically, such problems abstract in a natural way to the need to solve systems of Diophantine equations or systems of linear equations over polynomials. These and other problems involving polynomial matrices can in turn be reduced to polynomial matrix triangularization procedures, a result which is not surprising given the importance of matrix triangularization techniques in numerical linear algebra. Matrices with entries from a field and Gaussian elimination play a fundamental role in understanding the triangularization process. In the case of polynomial matrices, matrices with entries from a ring for which Gaussian elimination is not defined and triangularization is accomplished by what is quite properly called Euclidean elimination. Unfortunately, the numerical stability and sensitivity issues which accompany floating point approaches to Euclidean elimination are not very well understood. New algorithms are presented which circumvent entirely such numerical issues through the use of exact, symbolic methods in computer algebra. The use of such error-free algorithms guarantees that the results are accurate to within the precision of the model data--the best that can be hoped for. Care must be taken in the design of such algorithms due to the phenomenon of intermediate expressions swell.
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.
Liquid-crystalline physical gels.
Kato, Takashi; Hirai, Yuki; Nakaso, Suguru; Moriyama, Masaya
2007-12-01
Liquid-crystalline (LC) physical gels are a new class of dynamically functional materials consisting of liquid crystals and fibrous aggregates of molecules that are called "gelators". Liquid-crystalline physical gels, which are macroscopically soft solids, exhibit induced or enhanced electro-optical, photochemical, electronic properties due to the combination of two components that form phase-separated structures. In this tutorial review, we describe the materials design and structure-property relationships of the LC physical gels. The introduction of self-assembled fibers into nematic liquid crystals leads to faster responses in twisted nematic (TN) mode and high contrast switching in light scattering mode. Furthermore, the LC physical gels can be exploited as a new type of materials for electro-optical memory. This function is achieved by the control of reversible aggregation processes of gelators under electric fields in nematic liquid crystals. Electronic properties such as hole mobilities are improved by the introduction of fibrous aggregates into triphenylene-based columnar liquid crystals. The incorporation of photochromic azobenzenes or electroactive tetrathiafulvalenes into the chemical structures of gelators leads to the preparation of ordered functional materials.
NASA Astrophysics Data System (ADS)
Tielmann, Patrick; Kierkels, Hans; Zonta, Albin; Ilie, Adriana; Reetz, Manfred T.
2014-05-01
The entrapment of lipases in hydrophobic silicate matrices formed by sol-gel mediated hydrolysis of RSi(OCH3)3/Si(OCH3)4 as originally reported in 1996 has been improved over the years by a number of modifications. In the production of second-generation sol-gel lipase immobilizates, a variety of additives during the sol-gel process leads to increased activity and enhanced stereoselectivity in esterifying kinetic resolution. Recent advances in this type of lipase immobilization are reviewed here, in addition to new results regarding the sol-gel entrapment of the lipase from Burkholderia cepacia. It constitutes an excellent heterogeneous biocatalyst in the acylating kinetic resolution of two synthetically and industrially important chiral alcohols, rac-sulcatol and rac-trans-2-methoxycyclohexanol. The observation that the catalyst can be used 10 times in recycling experiments without losing its significant activity or enantioselectivity demonstrates the practical viability of the sol-gel approach.The entrapment of lipases in hydrophobic silicate matrices formed by sol-gel mediated hydrolysis of RSi(OCH3)3/Si(OCH3)4 as originally reported in 1996 has been improved over the years by a number of modifications. In the production of second-generation sol-gel lipase immobilizates, a variety of additives during the sol-gel process leads to increased activity and enhanced stereoselectivity in esterifying kinetic resolution. Recent advances in this type of lipase immobilization are reviewed here, in addition to new results regarding the sol-gel entrapment of the lipase from Burkholderia cepacia. It constitutes an excellent heterogeneous biocatalyst in the acylating kinetic resolution of two synthetically and industrially important chiral alcohols, rac-sulcatol and rac-trans-2-methoxycyclohexanol. The observation that the catalyst can be used 10 times in recycling experiments without losing its significant activity or enantioselectivity demonstrates the practical viability of
An alternative clean-up column for the determination of polychlorinated biphenyls in solid matrices.
Ndunda, Elizabeth N; Madadi, Vincent O; Mizaikoff, Boris
2015-12-01
The need for continuous monitoring of polychlorinated biphenyls (PCBs) has necessitated the development of analytical techniques that are sensitive and selective with minimal reagent requirement. In light of this, we developed a column for clean-up of soil and sediment extracts, which is less demanding in terms of the amount of solvent and sorbent. The dual-layer column consists of acidified silica gel and molecularly imprinted polymers (MIPs). MIPs were synthesized via aqueous suspension polymerization using PCB 15 as the dummy template, 4-vinylpyridine as the functional monomer and ethylene glycol dimethacrylate as the cross-linker and the obtained particles characterized via SEM, BET, and batch rebinding assays. Pre-concentration of the spiked real-world water sample using MISPE gave recoveries between 85.2 and 104.4% (RSD < 8.69). On the other hand, the specific dual-layer column designed for clean-up of extracts from complex matrices provided recoveries of 91.6-102.5% (RSD < 4%) for spiked soil, which was comparable to clean-up using acidified silica (70.4-90.5%; RSD < 3.72%) and sulfoxide modified silica (89.7-103.0%; RSD < 13.0%). However, the polymers were reusable maintaining recoveries of 79.8-111.8% after 30 cycles of regeneration and re-use, thereby availing a cost-effective clean-up procedure for continuous monitoring of PCBs. Method detection limits were 0.01-0.08 ng g(-1) and 0.002-0.01 ng mL(-1) for solid matrices and water, respectively.
NASA Astrophysics Data System (ADS)
Bachmann, Sabine; Thaller, Daniela; Roggenbuck, Ole; Lösler, Michael; Messerschmitt, Linda
2016-07-01
Every few years the International Terrestrial Reference System (ITRS) Center of the International Earth Rotation and Reference Systems Service (IERS) decides to generate a new version of the International Terrestrial Reference Frame (ITRF). For the upcoming ITRF2014 the official contribution of the International VLBI Service for Geodesy and Astrometry (IVS) comprises 5796 combined sessions in SINEX file format from 1979.6 to 2015.0 containing 158 stations, overall. Nine AC contributions were included in the combination process, using five different software packages. Station coordinate time series of the combined solution show an overall repeatability of 3.3 mm for the north, 4.3 mm for the east and 7.5 mm for the height component over all stations. The minimum repeatabilities are 1.5 mm for north, 2.1 mm for east and 2.9 mm for height. One of the important differences between the IVS contribution to the ITRF2014 and the routine IVS combination is the omission of the correction for non-tidal atmospheric pressure loading (NTAL). Comparisons between the amplitudes of the annual signals derived by the VLBI observations and the annual signals from an NTAL model show that for some stations, NTAL has a high impact on station height variation. For other stations, the effect of NTAL is low. Occasionally other loading effects have a higher influence (e.g. continental water storage loading). External comparisons of the scale parameter between the VTRF2014 (a TRF based on combined VLBI solutions), DTRF2008 (DGFI-TUM realization of ITRS) and ITRF2008 revealed a significant difference in the scale. A scale difference of 0.11 ppb (i.e. 0.7 mm on the Earth's surface) has been detected between the VTRF2014 and the DTRF2008, and a scale difference of 0.44 ppb (i.e. 2.8 mm on the Earth's surface) between the VTRF2014 and ITRF2008. Internal comparisons between the EOP of the combined solution and the individual solutions from the AC contributions show a WRMS in X- and Y-Pole between
Sweeping the space of admissible quark mass matrices
NASA Astrophysics Data System (ADS)
Falk, Silke; Häußling, Rainer; Scheck, Florian
2002-05-01
We propose a new and efficient method of reconstructing quark mass matrices from their eigenvalues and a complete set of mixing observables. By a combination of the principle of NNI bases which are known to cover the general case, and of the polar decomposition theorem that allows us to convert arbitrary nonsingular matrices to triangular form, we achieve a parametrization where the remaining freedom is reduced to one complex parameter. While this parameter runs through the domain bounded by the circle with radius R=((m2t-m2u)/(m2t-m2c)) around the origin in the complex plane one sweeps the space of all mass matrices compatible with the given set of data.
Scattering matrices in non-uniformly lined ducts
NASA Astrophysics Data System (ADS)
Demir, Ahmet
2017-02-01
Sudden area expansion and sudden area contraction in an infinitely long duct with discontinuous locally reacting lining are defined by respective mixed boundary value problems. In the absence of a sudden area change, a separate problem with an infinite duct having bifid lining on its wall is described. Introducing Fourier transform along the duct axis boundary value problems is solved by the well-known Wiener-Hopf technique, and then, corresponding scattering matrices are constructed. To show the proper use of scattering matrices in the case of several discontinuities and also validation and comparison purposes, transmitted field in a duct with an inserted expansion chamber whose walls are treated by acoustically absorbent material is derived by the help of the relevant scattering matrices. A perfect agreement is observed when the transmitted fields are compared numerically with a similar work exists in the literature.
Asymmetric correlation matrices: an analysis of financial data
NASA Astrophysics Data System (ADS)
Livan, G.; Rebecchi, L.
2012-06-01
We analyse the spectral properties of correlation matrices between distinct statistical systems. Such matrices are intrinsically non-symmetric, and lend themselves to extend the spectral analyses usually performed on standard Pearson correlation matrices to the realm of complex eigenvalues. We employ some recent random matrix theory results on the average eigenvalue density of this type of matrix to distinguish between noise and non-trivial correlation structures, and we focus on financial data as a case study. Namely, we employ daily prices of stocks belonging to the American and British stock exchanges, and look for the emergence of correlations between two such markets in the eigenvalue spectrum of their non-symmetric correlation matrix. We find several non trivial results when considering time-lagged correlations over short lags, and we corroborate our findings by additionally studying the asymmetric correlation matrix of the principal components of our datasets.
Large N matrices from a nonlocal spin system
NASA Astrophysics Data System (ADS)
Anninos, Dionysios; Hartnoll, Sean A.; Huijse, Liza; Martin, Victoria L.
2015-10-01
Large N matrices underpin the best understood models of emergent spacetime. We suggest that large N matrices can themselves be emergent from simple quantum mechanical spin models with finite dimensional Hilbert spaces. We exhibit the emergence of large N matrices in a nonlocal statistical physics model of order N2 Ising spins. The spin partition function is shown to admit a large N saddle described by a matrix integral, which we solve. The matrix saddle is dominant at high temperatures, metastable at intermediate temperatures and ceases to exist below a critical order one temperature. The matrix saddle is disordered in a sense we make precise and competes with ordered low energy states. We verify our analytic results by Monte Carlo simulation of the spin system.
Nano-Fiber Reinforced Enhancements in Composite Polymer Matrices
NASA Technical Reports Server (NTRS)
Chamis, Christos C.
2009-01-01
Nano-fibers are used to reinforce polymer matrices to enhance the matrix dependent properties that are subsequently used in conventional structural composites. A quasi isotropic configuration is used in arranging like nano-fibers through the thickness to ascertain equiaxial enhanced matrix behavior. The nano-fiber volume ratios are used to obtain the enhanced matrix strength properties for 0.01,0.03, and 0.05 nano-fiber volume rates. These enhanced nano-fiber matrices are used with conventional fiber volume ratios of 0.3 and 0.5 to obtain the composite properties. Results show that nano-fiber enhanced matrices of higher than 0.3 nano-fiber volume ratio are degrading the composite properties.
Complications of acellular dermal matrices in breast surgery.
Israeli, Ron
2012-11-01
Acellular dermal matrices have been used in breast surgery for a decade. They are widely used in implant-based breast reconstruction to provide coverage of the inferolateral aspects of the prosthesis. Numerous benefits have been reported with this approach including improved fold control, better support and control of the implant pocket with concomitant reduced risk of malposition, and improved lower pole expansion. Seroma, infection, mastectomy skin necrosis, and expander/implant loss are the most commonly reported complications with this approach, and the incidences vary widely among studies. Patient selection and adherence to established intraoperative technique principles related to acellular dermal matrix use are both critical to minimizing the risk of complications. Acellular dermal matrices are also being used in aesthetic breast surgery, revision breast surgery, and nipple reconstruction, but clinical experience is limited. This article reviews the complications associated with the use of matrices in breast surgery from the published literature.
Modeling quantization matrices for perceptual image / video encoding
NASA Astrophysics Data System (ADS)
Zhang, Huipin; Cote, Guy
2008-01-01
Quantization matrix is an important encoding tool for discrete cosine transform (DCT) based perceptual image / video encoding in that DCT coefficients can be quantized according to the sensitivity of the human visual system to the coefficients' corresponding spatial frequencies. A quadratic model is introduced to parameterize the quantization matrices. This model is then used to optimize quantization matrices for a specific bitrate or bitrate range by maximizing the expected encoding quality via a trial based multidimensional numerical search method. The model is simple yet it characterizes the slope and the convexity of the quantization matrices along the horizontal, the vertical and the diagonal directions. The advantage of the model for improving perceptual video encoding quality is demonstrated with simulations using H.264 / AVC video encoding.
Bleach Gel: A Simple Agarose Gel for Analyzing RNA Quality
Aranda, Patrick S.; LaJoie, Dollie M.; Jorcyk, Cheryl L.
2013-01-01
RNA-based applications requiring high quality, non-degraded RNA are a foundational element of many research studies. As such, it is paramount that the integrity of experimental RNA is validated prior to cDNA synthesis or other downstream applications. In the absence of expensive equipment such as microfluidic electrophoretic devices, and as an alternative to the costly and time-consuming standard formaldehyde gel, RNA quality can be quickly analyzed by adding small amounts of commercial bleach to TAE buffer-based agarose gels prior to electrophoresis. In the presence of low concentrations of bleach, the secondary structure of RNA is denatured and potential contaminating RNases are destroyed. Because of this, the ‘bleach gel’ is a functional approach that addresses the need for an inexpensive and safe way to evaluate RNA integrity and will improve the ability of researchers to rapidly analyze RNA quality. PMID:22222980
Effect of a gel containing pilocarpine on vaginal atrophy in castrated rats
de Sousa-Lages, Cristina A.; de Deus-Lages, Lívio P.; de Sousa, Gabriela V.; de Moura-Leal, Adinaide C.; Conde, Airton Mendes; Costa-Silva, Danylo Rafhael; da Conceição Barros-Oliveira, Maria; Borges, Carine Soares; Escórcio-Dourado, Carla Solange; Sampaio, Fabiane A.; Cunha-Nunes, Lívio C.; da-Silva, Benedito B.
2016-01-01
OBJECTIVES: To evaluate the effect of Carbopol gel formulations containing pilocarpine on the morphology and morphometry of the vaginal epithelium of castrated rats. METHODS: Thirty-one female Wistar-Hannover rats were randomly divided into four groups: the control Groups I (n=7, rats in persistent estrus; positive controls) and II (n=7, castrated rats, negative controls) and the experimental Groups, III (n=8) and IV (n=9). Persistent estrus (Group I) was achieved with a subcutaneous injection of testosterone propionate on the second postnatal day. At 90 days postnatal, rats in Groups II, III and IV were castrated and treated vaginally for 14 days with Carbopol gel (vehicle alone) or Carbopol gel containing 5% and 15% pilocarpine, respectively. Next, all of the animals were euthanized and their vaginas were removed for histological evaluation. A non-parametric test with a weighted linear regression model was used for data analysis (p<0.05). RESULTS: The morphological evaluation showed maturation of the vaginal epithelium with keratinization in Group I, whereas signs of vaginal atrophy were present in the rats of the other groups. Morphometric examinations showed mean thickness values of the vaginal epithelium of 195.10±12.23 μm, 30.90±1.14 μm, 28.16±2.98 μm and 29.84±2.30 μm in Groups I, II, III and IV, respectively, with statistically significant differences between Group I and the other three groups (p<0.0001) and no differences between Groups II, III and IV (p=0.0809). CONCLUSION: Topical gel formulations containing pilocarpine had no effect on atrophy of the vaginal epithelium in the castrated female rats. PMID:27276400
Optical and Infrared Interferometry IV
NASA Astrophysics Data System (ADS)
Rajagopal, Jayadev K.; Creech-Eakman, Michelle J.; Malbet, Fabien
2014-08-01
Optical and IR Interferometry IV at the SPIE 2014 symposium in Montreal had a strong and vibrant program. After initial fears about budget cuts and travel-funding constraints, the Program Committee had to work hard to accommodate as many quality submissions as possible. Innovative, creative and visionary work ensured that the field has progressed well, despite the bleak funding climate felt in the US, Europe and elsewhere. Montreal proved an excellent venue for this, the largest of Interferometry conferences and the only one that brings together practitioners from the world over. Let us summarize a few highlights to convey a glimpse of the excitement that is detailed in the rest of these Proceedings.
Suzawa, Yoshika; Funaki, Takafumi; Watanabe, Junji; Iwai, Soichi; Yura, Yoshiaki; Nakano, Takayoshi; Umakoshi, Yukichi; Akashi, Mitsuru
2010-06-01
The main objective of this study was to evaluate the biological behavior of Hydroxyapatite (HAp)/agarose and calcium carbonate (CaCO3)/agarose composite gels by an alternate soaking process used for the treatment of surgically produced bone defects in rat cranium. We designed the following four groups: (i) HAp (HAp/agarose composite gel), (ii) CaCO3 (CaCO3/agarose composite gel), (iii) Agarose (bare agarose gel), and (iv) Defect (no filling materials). We subdivided (i) (ii) (iii) into two application types as a (I) Homogenized Group (homogenized materials) and a (II) Disk Group (disk shaped materials). We assessed samples by radiological and histological analyses 0, 4, and 8 weeks after implantation. The results indicated that the composite gels showed higher radiopacity in microfocus-computed tomography (muCT) images and showed higher volume in quantitative analyses using Dual Energy X-ray Absorptiometry (DEXA) and Peripheral Quantitative Computed Tomography (pQCT) than the Agarose and Defect groups. The histological examination showed characteristic images due to each application form. Consequently, HAp and CaCO3/agarose composite gels can be expected to accelerate the speed of producing more new bone associated with osteogenesis. These novel biomaterials play an important role as an alternative biocompatible and biodegradable bone grafting filler material for autogenous bone.
Clindamycin phosphate 1% gel in acne vulgaris.
Rizer, R L; Sklar, J L; Whiting, D; Bucko, A; Shavin, J; Jarratt, M
2001-01-01
A 12-week study compared Clindagel, a unique water-based gel formulation of clindamycin phosphate 1%, administered once daily, and Cleocin T, a slightly different gel formulation indicated for twice-daily use, in the treatment of acne vulgaris. Clindagel was safe and effective and equivalent to Cleocin T gel, albeit with a better tolerability profile. Clindagel is a viable alternative to Cleocin T gel.
β-Diketones and their derivatives in sol-gel processes
NASA Astrophysics Data System (ADS)
Zolotareva, N. V.; Semenov, V. V.
2013-10-01
Published data on the use of β-diketones, metal β-diketonates and some structurally related compounds in sol-gel synthesis of new organic-inorganic hybrid materials are analyzed. Functionalization methods of β-diketones with carbofunctional organosilicon compounds are considered. Ways of insertion of a metal cation into the organic-inorganic hybrid matrix using non-functionalized β-diketonates are demonstrated. Particular attention is devoted to luminescent lanthanide derivatives, which is due to the prospects of practical application of materials obtained from them in photonics, integrated optics and medical diagnosis. The types and properties of most widely used sol-gel monomers and oligomers and the luminescence behaviour of lanthanide β-diketonates and metal-free silica matrices are considered. The bibliography includes 220 references.
Balanced 0, + or - Matrices. Part 2. Recognition Algorithm
1994-01-22
Matrices MAY 101994 Part II: Recognition Algorithm D Michele ConfortlI G6rard Cornu6j~ls2 Ajai Kapoor Krisina Vuskovi 2 January 22, 1994 Dipartimento...di Matematica Pura ed Applicata Universiti di Padova, Via Belzoni 7, 94-13892 35131 Padova, Italy I IIII In II ii I l1i III Graduate School of...for balanced 0, ± matrices . This algorithm is based on a decomposition theorem proved in a companion paper. Acce166 ýr7 NTIS CRA& D’BC TAB L 1 U
Random reverse-cyclic matrices and screened harmonic oscillator
NASA Astrophysics Data System (ADS)
Srivastava, Shashi C. L.; Jain, Sudhir R.
2012-04-01
We have calculated the joint probability distribution function for random reverse-cyclic matrices and shown that it is related to an N-body exactly solvable model. We refer to this well-known model potential as a screened harmonic oscillator. The connection enables us to obtain all the correlations among the particle positions moving in a screened harmonic potential. The density of nontrivial eigenvalues of this ensemble is found to be of the Wigner form and admits a hole at the origin, in contrast to the semicircle law of the Gaussian orthogonal ensemble of random matrices. The spacing distributions assume different forms ranging from Gaussian-like to Wigner.
The algebraic theory of latent projectors in lambda matrices
NASA Technical Reports Server (NTRS)
Denman, E. D.; Leyva-Ramos, J.; Jeon, G. J.
1981-01-01
Multivariable systems such as a finite-element model of vibrating structures, control systems, and large-scale systems are often formulated in terms of differential equations which give rise to lambda matrices. The present investigation is concerned with the formulation of the algebraic theory of lambda matrices and the relationship of latent roots, latent vectors, and latent projectors to the eigenvalues, eigenvectors, and eigenprojectors of the companion form. The chain rule for latent projectors and eigenprojectors for the repeated latent root or eigenvalues is given.
Quantum hidden Markov models based on transition operation matrices
NASA Astrophysics Data System (ADS)
Cholewa, Michał; Gawron, Piotr; Głomb, Przemysław; Kurzyk, Dariusz
2017-04-01
In this work, we extend the idea of quantum Markov chains (Gudder in J Math Phys 49(7):072105 [3]) in order to propose quantum hidden Markov models (QHMMs). For that, we use the notions of transition operation matrices and vector states, which are an extension of classical stochastic matrices and probability distributions. Our main result is the Mealy QHMM formulation and proofs of algorithms needed for application of this model: Forward for general case and Vitterbi for a restricted class of QHMMs. We show the relations of the proposed model to other quantum HMM propositions and present an example of application.
Bifactor Modeling and the Estimation of Model-Based Reliability in the WAIS-IV.
Gignac, Gilles E; Watkins, Marley W
2013-09-01
Previous confirmatory factor analytic research that has examined the factor structure of the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) has endorsed either higher order models or oblique factor models that tend to amalgamate both general factor and index factor sources of systematic variance. An alternative model that has not yet been examined for the WAIS-IV is the bifactor model. Bifactor models allow all subtests to load onto both the general factor and their respective index factor directly. Bifactor models are also particularly amenable to the estimation of model-based reliabilities for both global composite scores (ω h ) and subscale/index scores (ω s ). Based on the WAIS-IV normative sample correlation matrices, a bifactor model that did not include any index factor cross loadings or correlated residuals was found to be better fitting than the conventional higher order and oblique factor models. Although the ω h estimate associated with the full scale intelligence quotient (FSIQ) scores was respectably high (.86), the ω s estimates associated with the WAIS-IV index scores were very low (.13 to .47). The results are interpreted in the context of the benefits of a bifactor modeling approach. Additionally, in light of the very low levels of unique internal consistency reliabilities associated with the index scores, it is contended that clinical index score interpretations are probably not justifiable.
Study of Fricke gel dosimeter response for different gel quality
NASA Astrophysics Data System (ADS)
Cavinato, C. C.; Campos, L. L.
2010-11-01
The Fricke xylenol gel (FXG) dosimeter has been studied for application in radiotherapy because it is capable of to measure the spatial distribution of radiation doses. The dosimetry is based on the oxidation of ferrous (Fe2+) to ferric (Fe3+) ions radiation induced, related to the radiation dose. The gel material usually employed is the 300 Bloom gelatin, which is imported and very expensive in Brazil. Aiming to analyze the viability of to use a locally produced and low cost gel material, in this work the spectrophotometric responses of FXG solutions prepared using 270 Bloom gelatin commercially available and 300 Bloom gelatin imported were compared. The absorption spectra of solutions prepared with 5% by weight 270 and 300 Bloom gelatins non-irradiated and irradiated with 60Co gamma radiation in the dose range between 0.5 and 100 Gy were analysed, the dose-response curves were evaluated and the useful dose range was established. The obtained results indicate that the FXG solution prepared with 270 Bloom gelatin presents good performance, similar to that presented by the FXG solution prepared with 300 Bloom gelatin and its use can be recommended owing to the low cost and the availability in local market.
UV-Induced unimolecular photochemistry of diketene isolated in cryogenic inert matrices.
Breda, S; Reva, I; Fausto, R
2012-03-08
Diketene (C(4)H(4)O(2)) monomers were isolated in cryogenic Ar (15 K) and Xe (30 K) matrices. The infrared (IR) spectra of the freshly deposited matrices show that diketene monomers exclusively adopt the 4-methylene-oxetan-2-one form. In situ photochemical transformations of diketene were induced by tunable UV laser light. Diketene was found to be photostable when exposed to near-UV irradiations (λ> 300 nm). Irradiations in the middle-UV domain showed different types of photochemical reactivity occurring upon irradiations with 280 > λ > 240 nm and λ = 225 nm. The photoproducts were characterized by IR spectroscopy supported by B3LYP/6-311++G(d,p) calculations. Upon irradiation in the 280 > λ > 225 nm range, diketene was found to decompose in two ways: (i) with production of two parent ketene molecules (O═C═CH(2)), and (ii) with production of cyclopropanone (CP) plus carbon monoxide. For irradiations in the 280 > λ > 240 nm range, diketene exhibited two additional reactions: (iii) decomposition to allene (H(2)C═C═CH(2)) and carbon dioxide, and (iv) isomerization into cyclobutane-1,3-dione (CB). Of the above photoproducts, CP and CB were consumed by the same UV irradiations that resulted in their generation. Positive spectroscopic identification of CP and CB turned out to be possible with near-UV irradiations: CP decomposes to ethylene and carbon monoxide upon irradiation with λ = 345 nm; CB decomposes exclusively to two parent ketene molecules, without isomerization back to diketene or decarbonylation, upon irradiation with λ = 330 nm. Natural bond orbital (NBO) analysis showed that the two lowest excited singlet states of diketene are almost degenerate in energy and correspond to π* orbitals of C═C and C═O moieties. The NBO calculations helped to establish that the third excited singlet state, in terms of energy, has σ*(3s) Rydberg character, in accord with the literature.
Spring-loaded polymeric gel actuators
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.
Spring-loaded polymeric gel actuators
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.
Nanocrystal/sol-gel nanocomposites
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.
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
He, Xun; Fan, Jingwei; Wooley, Karen L
2016-02-18
The past decade has witnessed significantly increased interest in the development of smart polypeptide-based organo- and hydrogel systems with stimuli responsiveness, especially those that exhibit sol-gel phase-transition properties, with an anticipation of their utility in the construction of adaptive materials, sensor designs, and controlled release systems, among other applications. Such developments have been facilitated by dramatic progress in controlled polymerizations of α-amino acid N-carboxyanhydrides (NCAs), together with advanced orthogonal functionalization techniques, which have enabled economical and practical syntheses of well-defined polypeptides and peptide hybrid polymeric materials. One-dimensional stacking of polypeptides or peptide aggregations in the forms of certain ordered conformations, such as α helices and β sheets, in combination with further physical or chemical cross-linking, result in the construction of three-dimensional matrices of polypeptide gel systems. The macroscopic sol-gel transitions, resulting from the construction or deconstruction of gel networks and the conformational changes between secondary structures, can be triggered by external stimuli, including environmental factors, electromagnetic fields, and (bio)chemical species. Herein, the most recent advances in polypeptide gel systems are described, covering synthetic strategies, gelation mechanisms, and stimuli-triggered sol-gel transitions, with the aim of demonstrating the relationships between chemical compositions, supramolecular structures, and responsive properties of polypeptide-based organo- and hydrogels.
The gel electrophoresis markup language (GelML) from the Proteomics Standards Initiative.
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
2010-09-01
The Human Proteome Organisation's Proteomics Standards Initiative has developed the GelML (gel electrophoresis markup language) 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 MS 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.
Quantitative mass spectrometry of unconventional human biological matrices
NASA Astrophysics Data System (ADS)
Dutkiewicz, Ewelina P.; Urban, Pawel L.
2016-10-01
The development of sensitive and versatile mass spectrometric methodology has fuelled interest in the analysis of metabolites and drugs in unconventional biological specimens. Here, we discuss the analysis of eight human matrices-hair, nail, breath, saliva, tears, meibum, nasal mucus and skin excretions (including sweat)-by mass spectrometry (MS). The use of such specimens brings a number of advantages, the most important being non-invasive sampling, the limited risk of adulteration and the ability to obtain information that complements blood and urine tests. The most often studied matrices are hair, breath and saliva. This review primarily focuses on endogenous (e.g. potential biomarkers, hormones) and exogenous (e.g. drugs, environmental contaminants) small molecules. The majority of analytical methods used chromatographic separation prior to MS; however, such a hyphenated methodology greatly limits analytical throughput. On the other hand, the mass spectrometric methods that exclude chromatographic separation are fast but suffer from matrix interferences. To enable development of quantitative assays for unconventional matrices, it is desirable to standardize the protocols for the analysis of each specimen and create appropriate certified reference materials. Overcoming these challenges will make analysis of unconventional human biological matrices more common in a clinical setting. This article is part of the themed issue 'Quantitative mass spectrometry'.
Technologies for detecting botulinum neurotoxins in biological and environmental matrices
Technology Transfer Automated Retrieval System (TEKTRAN)
Biomonitoring of food and environmental matrices is critical for the rapid and sensitive diagnosis, treatment, and prevention of diseases caused by toxins. The United States Centers for Disease Control and Prevention (CDC) has noted that toxins from bacteria, fungi, algae, and plants present an ongo...
Controlled growth factor release from synthetic extracellular matrices
NASA Astrophysics Data System (ADS)
Lee, Kuen Yong; Peters, Martin C.; Anderson, Kenneth W.; Mooney, David J.
2000-12-01
Polymeric matrices can be used to grow new tissues and organs, and the delivery of growth factors from these matrices is one method to regenerate tissues. A problem with engineering tissues that exist in a mechanically dynamic environment, such as bone, muscle and blood vessels, is that most drug delivery systems have been designed to operate under static conditions. We thought that polymeric matrices, which release growth factors in response to mechanical signals, might provide a new approach to guide tissue formation in mechanically stressed environments. Critical design features for this type of system include the ability to undergo repeated deformation, and a reversible binding of the protein growth factors to polymeric matrices to allow for responses to repeated stimuli. Here we report a model delivery system that can respond to mechanical signalling and upregulate the release of a growth factor to promote blood vessel formation. This approach may find a number of applications, including regeneration and engineering of new tissues and more general drug-delivery applications.
Advances in detection of antipsychotics in biological matrices.
Patteet, Lisbeth; Cappelle, Delphine; Maudens, Kristof E; Crunelle, Cleo L; Sabbe, Bernard; Neels, Hugo
2015-02-20
Measuring antipsychotic concentrations in human matrices is important for both therapeutic drug monitoring and forensic toxicology. This review provides a critical overview of the analytical methods for detection and quantification of antipsychotics published in the last four years. Focus lies on advances in sample preparation, analytical techniques and alternative matrices. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is used most often for quantification of antipsychotics. This sensitive technique makes it possible to determine low concentrations not only in serum, plasma or whole blood, but also in alternative matrices like oral fluid, dried blood spots, hair, nails and other body tissues. Current literature on analytical techniques for alternative matrices is still limited and often requires a more thorough validation including a comparison between conventional and alternative results to determine their actual value. Ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) makes it possible to quantify a high amount of compounds within a shorter run time. This technique is widely used for multi-analyte methods. Only recently, high-resolution mass spectrometry has gained importance when a combination of screening of (un)known metabolites, and quantification is required.
A Role for M-Matrices in Modelling Population Growth
ERIC Educational Resources Information Center
James, Glyn; Rumchev, Ventsi
2006-01-01
Adopting a discrete-time cohort-type model to represent the dynamics of a population, the problem of achieving a desired total size of the population under a balanced growth (contraction) and the problem of maintaining the desired size, once achieved, are studied. Properties of positive-time systems and M-matrices are used to develop the results,…
Development of epoxy matrices for filament-wound graphite structures
Morgan, R.J.; Walkup, C.M.; Kong, F.M.; Mones, E.T.
1984-11-27
This paper reviews our program to develop epoxy matrix systems for filament-wound graphite structures. The criteria for this matrix development program requires that the epoxide and amine components are processible and non-toxic; and the corresponding matrix itself is tough, possesses a Tg > 120/sup 0/C and does not lose its mechanical-thermal properties upon exposure to service environment conditions. We report our data on processible, hindered amine cured-epoxide matrices such as menthane or 2,5 dimethyl 2,5 hexane diamine cured bis-phenol-A-diglycidyl ether (DGEBA) epoxide systems in the presence of viscosity-lowering diluents. To produce tough, processible matrices that do not deteriorate upon exposure to service environment conditions requires a knowledge of the network structure formed and how such structure may deteriorate under molecular flow associated with the shear-band toughening mechanisms. For amine-cured DGEBA matrices we report deterioration in the mechanical response and Tg after plastic flow has occurred in such glasses. Permanent chemical changes that occur during this flow induced degradation process were monitored by stress-Fourier transform infrared spectroscopy. The ability to eliminate the aging of tough, cross-linked composite matrices upon molecular flow is discussed in terms of networks with segments of equal extensibility. 15 references, 4 figures, 2 tables.
A Note on the Drazin Indices of Square Matrices
Yu, Lijun; Bu, Tianyi; Zhou, Jiang
2014-01-01
For a square matrix A, the smallest nonnegative integer k such that rank (Ak) = rank (Ak+1) is called the Drazin index of A. In this paper, we give some results on the Drazin indices of sum and product of square matrices. PMID:24683337
Automorphisms of semigroups of invertible matrices with nonnegative integer elements
Semenov, Pavel P
2012-09-30
Let G{sub n}(Z) be the subsemigroup of GL{sub n}(Z) consisting of the matrices with nonnegative integer coefficients. In the paper, the automorphisms of this semigroup are described for n{>=}2. Bibliography: 5 titles.
Current technologies for detection of ricin in different matrices
Technology Transfer Automated Retrieval System (TEKTRAN)
Ricin is a convenient, potent, and available toxin for terrorist acts. The importance of detecting it in various matrices is obvious. This chapter reviews methods for ricin detection based on the mechanisms used for assay development. Five detection approaches are reviewed: 1. Antibody-based metho...
Validating Alternative Modes of Scoring for Coloured Progressive Matrices.
ERIC Educational Resources Information Center
Razel, Micha; Eylon, Bat-Sheva
Conventional scoring of the Coloured Progressive Matrices (CPM) was compared with three methods of multiple weight scoring. The methods include: (1) theoretical weighting in which the weights were based on a theory of cognitive processing; (2) judged weighting in which the weights were given by a group of nine adult expert judges; and (3)…
Inverse of polynomial matrices in the irreducible form
NASA Technical Reports Server (NTRS)
Chang, Fan R.; Shieh, Leang S.; Mcinnis, Bayliss C.
1987-01-01
An algorithm is developed for finding the inverse of polynomial matrices in the irreducible form. The computational method involves the use of the left (right) matrix division method and the determination of linearly dependent vectors of the remainders. The obtained transfer function matrix has no nontrivial common factor between the elements of the numerator polynomial matrix and the denominator polynomial.
Cluster Matrices for Health Occupations. Education for Employment Task Lists.
ERIC Educational Resources Information Center
Lathrop, Janice
These cluster matrices provide duties and tasks that form the basis of instructional content for secondary, postsecondary, and adult training programs for health occupations. The eight clusters (and the job titles included in each cluster) are as follows: (1) dental assisting (dental assistant); (2) dental laboratory technology (dental laboratory…
Dimensionality of Data Matrices with Applications to Gene Expression Profiles
ERIC Educational Resources Information Center
Feng, Xingdong
2009-01-01
Probe-level microarray data are usually stored in matrices. Take a given probe set (gene), for example, each row of the matrix corresponds to an array, and each column corresponds to a probe. Often, people summarize each array by the gene expression level. Is one number sufficient to summarize a whole probe set for a specific gene in an array?…
Evaluation of Commercially Available Cyanide Test Kits against Various Matrices
2016-08-01
EVALUATION OF COMMERCIALLY AVAILABLE CYANIDE TEST KITS AGAINST VARIOUS MATRICES ECBC-TR-1382 Darren W. Hicklin...3. DATES COVERED (From - To) Mar 2015 – Sep 2015 4. TITLE AND SUBTITLE Evaluation of Commercially Available Cyanide Test Kits against Various...available cyanide -detection test kits or strips were selected for evaluation based upon a premarket survey: Quantofix test strips, Cyantesmo test paper
Products of rectangular random matrices: singular values and progressive scattering.
Akemann, Gernot; Ipsen, Jesper R; Kieburg, Mario
2013-11-01
We discuss the product of M rectangular random matrices with independent Gaussian entries, which have several applications, including wireless telecommunication and econophysics. For complex matrices an explicit expression for the joint probability density function is obtained using the Harish-Chandra-Itzykson-Zuber integration formula. Explicit expressions for all correlation functions and moments for finite matrix sizes are obtained using a two-matrix model and the method of biorthogonal polynomials. This generalizes the classical result for the so-called Wishart-Laguerre Gaussian unitary ensemble (or chiral unitary ensemble) at M=1, and previous results for the product of square matrices. The correlation functions are given by a determinantal point process, where the kernel can be expressed in terms of Meijer G-functions. We compare the results with numerical simulations and known results for the macroscopic level density in the limit of large matrices. The location of the end points of support for the latter are analyzed in detail for general M. Finally, we consider the so-called ergodic mutual information, which gives an upper bound for the spectral efficiency of a MIMO communication channel with multifold scattering.
Generalized Pure Density Matrices and the Standard Model
NASA Astrophysics Data System (ADS)
Brannen, Carl
2015-04-01
We consider generalizations of pure density matrices that have ρρ = ρ , but give up the trace=1 requirement. Given a representation of a quantum algebra in N × N complex matrices, the elements that satisfy ρρ = ρ can be taken to be pure density matrix states. In the Standard Model, particles from different ``superselection sectors'' cannot form linear superpositions. For example, it is impossible to form a linear superposition between an electron and a neutrino. We report that some quantum algebras give symmetry, particle and generation content, gauge freedom, and superselection sectors that are similar to those of the Standard Model. Our lecture will consider as an example the 4 × 4 complex matrices. There are 16 that are diagonal with ρρ = ρ . The 4 with trace=1 give the usual pure density matrices. We will show that the 6 with trace=2 form an SU(3) triplet of three superselection sectors, with each sector consisting of an SU(2) doublet. Considering one of these sectors, the mapping to SU(2) is not unique; there is an SU(2) gauge freedom. This gauge freedom is an analogy to the U(1) gauge freedom that arises when converting a pure density matrix to a state vector.
More about unphysical zeroes in quark mass matrices
NASA Astrophysics Data System (ADS)
Emmanuel-Costa, David; González Felipe, Ricardo
2017-01-01
We look for all weak bases that lead to texture zeroes in the quark mass matrices and contain a minimal number of parameters in the framework of the standard model. Since there are ten physical observables, namely, six nonvanishing quark masses, three mixing angles and one CP phase, the maximum number of texture zeroes in both quark sectors is altogether nine. The nine zero entries can only be distributed between the up- and down-quark sectors in matrix pairs with six and three texture zeroes or five and four texture zeroes. In the weak basis where a quark mass matrix is nonsingular and has six zeroes in one sector, we find that there are 54 matrices with three zeroes in the other sector, obtainable through right-handed weak basis transformations. It is also found that all pairs composed of a nonsingular matrix with five zeroes and a nonsingular and nondecoupled matrix with four zeroes simply correspond to a weak basis choice. Without any further assumptions, none of these pairs of up- and down-quark mass matrices has physical content. It is shown that all non-weak-basis pairs of quark mass matrices that contain nine zeroes are not compatible with current experimental data. The particular case of the so-called nearest-neighbour-interaction pattern is also discussed.
Cleaning large correlation matrices: Tools from Random Matrix Theory
NASA Astrophysics Data System (ADS)
Bun, Joël; Bouchaud, Jean-Philippe; Potters, Marc
2017-01-01
This review covers recent results concerning the estimation of large covariance matrices using tools from Random Matrix Theory (RMT). We introduce several RMT methods and analytical techniques, such as the Replica formalism and Free Probability, with an emphasis on the Marčenko-Pastur equation that provides information on the resolvent of multiplicatively corrupted noisy matrices. Special care is devoted to the statistics of the eigenvectors of the empirical correlation matrix, which turn out to be crucial for many applications. We show in particular how these results can be used to build consistent "Rotationally Invariant" estimators (RIE) for large correlation matrices when there is no prior on the structure of the underlying process. The last part of this review is dedicated to some real-world applications within financial markets as a case in point. We establish empirically the efficacy of the RIE framework, which is found to be superior in this case to all previously proposed methods. The case of additively (rather than multiplicatively) corrupted noisy matrices is also dealt with in a special Appendix. Several open problems and interesting technical developments are discussed throughout the paper.
Satir, Funda; Toptas, Tayfun; Inel, Murat; Erman-Akar, Munire; Taskin, Omur
2013-06-01
The main objective of this study was to compare the pregnancy rates of intramuscular (IM) 17-α-hydroxyprogesterone caproate (17-HPC) and intravaginal (IV) progesterone gel administration in in vitro fertilization-embryo transfer (IVF-ET) cycles. The IM 17-HPC and IV progesterone groups included 632 (66.4%) and 320 (33.6%) women undergoing the first cycles of IVF-ET treatment, respectively. Multivariate analyses annotated for all potential confounders showed that the use of IV progesterone retained a predictive value for the total β-human chorionic gonadotropin (hCG) positivity and clinical pregnancy rates [adjusted odds ratio (OR), 1.97; 95% confidence interval (CI), 1.28-3.03; P=0.002; and OR, 1.66; 95% CI, 1.07-2.60; P=0.03, respectively]. However, biochemical and on-going pregnancy rates did not differ significantly between the groups (OR, 1.85; 95% CI, 1.00-3.41; P=0.05; and OR, 1.43, 95% CI, 0.89-2.30; P=0.14, respectively). Luteal phase support (LPS) with IV progesterone gel in comparison with IM 17-HPC appears to be associated with higher clinical pregnancy rates in IVF-ET cycles. However, this benefit is clinically irrelevant in terms of on-going pregnancy outcomes.
SATIR, FUNDA; TOPTAS, TAYFUN; INEL, MURAT; ERMAN-AKAR, MUNIRE; TASKIN, OMUR
2013-01-01
The main objective of this study was to compare the pregnancy rates of intramuscular (IM) 17-α-hydroxyprogesterone caproate (17-HPC) and intravaginal (IV) progesterone gel administration in in vitro fertilization-embryo transfer (IVF-ET) cycles. The IM 17-HPC and IV progesterone groups included 632 (66.4%) and 320 (33.6%) women undergoing the first cycles of IVF-ET treatment, respectively. Multivariate analyses annotated for all potential confounders showed that the use of IV progesterone retained a predictive value for the total β-human chorionic gonadotropin (hCG) positivity and clinical pregnancy rates [adjusted odds ratio (OR), 1.97; 95% confidence interval (CI), 1.28–3.03; P=0.002; and OR, 1.66; 95% CI, 1.07–2.60; P=0.03, respectively]. However, biochemical and on-going pregnancy rates did not differ significantly between the groups (OR, 1.85; 95% CI, 1.00–3.41; P=0.05; and OR, 1.43, 95% CI, 0.89–2.30; P=0.14, respectively). Luteal phase support (LPS) with IV progesterone gel in comparison with IM 17-HPC appears to be associated with higher clinical pregnancy rates in IVF-ET cycles. However, this benefit is clinically irrelevant in terms of on-going pregnancy outcomes. PMID:23837065
Effect of propolis gel on the in vitro reduction of dentin permeability
SALES-PERES, Silvia Helena de Carvalho; de CARVALHO, Flávia Negreiros; MARSICANO, Juliane Avansini; MATTOS, Maria Cecília; PEREIRA, José Carlos; FORIM, Moacir Rossi; da SILVA, Maria Fatima das Graças Fernandes
2011-01-01
Objective The aim of this study was to evaluate the capacity of potassium oxalate, fluoride gel and two kinds of propolis gel to reduce the hydraulic conductance of dentin, in vitro. Material and Methods The methodology used for the measurement of hydraulic conductance of dentin in the present study was based on a model proposed in literature. Thirty-six 1-mm-thick dentin discs, obtained from extracted human third molars were divided into 4 groups (n=9). The groups corresponded to the following experimental materials: GI-10% propolis gel, pH 4.1; GII-30% propolis gel; GIII-3% potassium oxalate gel, pH 4,1; and GIV-1.23% fluoride gel, pH 4.1, applied to the dentin under the following surface conditions: after 37% phosphoric acid and before 6% citric acid application. The occluding capacity of the dentin tubules was evaluated using scanning electron microscopy (SEM) at ×500, ×1,000 and ×2,000 magnifications. Data were analyzed statistically by two-way ANOVA and Tukey's test at 5% significance level. Results Groups I, II, III, IV did not differ significantly from the others in any conditions by reducing in hydraulic conductance. The active agents reduced dentin permeability; however they produced the smallest reduction in hydraulic conductance when compared to the presence of smear layer (P<0.05). The effectiveness in reducing dentin permeability did not differ significantly from 10% or 30% propolis gels. SEM micrographs revealed that dentin tubules were partially occluded after treatment with propolis. Conclusions Under the conditions of this study, the application of 10% and 30% propolis gels did not seem to reduce the hydraulic conductance of dentin in vitro, but it showed capacity of partially obliterating the dentin tubules. Propolis is used in the treatment of different oral problems without causing significant great collateral effects, and can be a good option in the treatment of patients with dentin sensitivity. PMID:21956588
Rotation-based technique for the rapid densification of tubular collagen gel scaffolds.
Loy, Caroline; Lainé, Audrey; Mantovani, Diego
2016-12-01
Type I collagen gel is often used as a tubular scaffold because of its easy molding properties as well as its biocompatibility, low immunogenicity and ability to be remodelled by cells. However, its highly hydrated structure contributes to its weak mechanical properties and reduces its ability to be handled, which is important in tubular tissue engineering. Although cell-driven remodelling of collagen matrices is known to reinforce their mechanical properties, this process can take weeks. This study introduces a novel, simple, and rapid technique using a rotational bioreactor to expel water and densify collagen under sterile conditions to generate denser and stronger collagen gel scaffolds. This process produces a dense tubular-shaped collagen gel which, compared to standard collagen gel scaffolds, shows a decreased wall thickness and a four-fold increase in collagen concentration. A denser collagen fiber network observed by immunofluorescence staining and mechanical characterisation shows a twenty-fold increase in the elastic modulus of the dense constructs which maintain cell viability inside the scaffold. Moreover, by simply modifying the scaffold mold, customised shapes and sizes can be obtained to provide a wide range of applications, including complex tubular geometries and multi-layered scaffolds for the culture of various cell types and tissues.
Antibacterial Peptide-Based Gel for Prevention of Medical Implanted-Device Infection
Mateescu, Mihaela; Baixe, Sébastien; Garnier, Tony; Jierry, Loic; Ball, Vincent; Haikel, Youssef; Metz-Boutigue, Marie Hélène; Nardin, Michel; Schaaf, Pierre; Etienne, Olivier; Lavalle, Philippe
2015-01-01
Implanted medical devices are prone to infection. Designing new strategies to reduce infection and implant rejection are an important challenge for modern medicine. To this end, in the last few years many hydrogels have been designed as matrices for antimicrobial molecules destined to fight frequent infection found in moist environments like the oral cavity. In this study, two types of original hydrogels containing the antimicrobial peptide Cateslytin have been designed. The first hydrogel is based on alginate modified with catechol moieties (AC gel). The choice of these catechol functional groups which derive from mussel’s catechol originates from their strong adhesion properties on various surfaces. The second type of gel we tested is a mixture of alginate catechol and thiol-terminated Pluronic (AC/PlubisSH), a polymer derived from Pluronic, a well-known biocompatible polymer. This PlubisSH polymer has been chosen for its capacity to enhance the cohesion of the composition. These two gels offer new clinical uses, as they can be injected and jellify in a few minutes. Moreover, we show these gels strongly adhere to implant surfaces and gingiva. Once gelled, they demonstrate a high level of rheological properties and stability. In particular, the dissipative energy of the (AC/PlubisSH) gel detachment reaches a high value on gingiva (10 J.m-2) and on titanium alloys (4 J.m-2), conferring a strong mechanical barrier. Moreover, the Cateslytin peptide in hydrogels exhibited potent antimicrobial activities against P. gingivalis, where a strong inhibition of bacterial metabolic activity and viability was observed, indicating reduced virulence. Gel biocompatibility tests indicate no signs of toxicity. In conclusion, these new hydrogels could be ideal candidates in the prevention and/or management of periimplant diseases. PMID:26659616
24 CFR Appendixes I-Iv to Subpart B - Appendixes I-IV to Subpart B
Code of Federal Regulations, 2012 CFR
2012-04-01
... 24 Housing and Urban Development 4 2012-04-01 2012-04-01 false Appendixes I-IV to Subpart B I Appendixes I-IV to Subpart B Housing and Urban Development REGULATIONS RELATING TO HOUSING AND URBAN... Appendixes I-IV to Subpart B Appendix I—Annual Contributions Contract “Special Provisions for Turnkey...
24 CFR Appendixes I-Iv to Subpart B - Appendixes I-IV to Subpart B
Code of Federal Regulations, 2014 CFR
2014-04-01
... 24 Housing and Urban Development 4 2014-04-01 2014-04-01 false Appendixes I-IV to Subpart B I Appendixes I-IV to Subpart B Housing and Urban Development REGULATIONS RELATING TO HOUSING AND URBAN... Appendixes I-IV to Subpart B Appendix I—Annual Contributions Contract “Special Provisions for Turnkey...
Metsahovi Radio Observatory - IVS Network Station
NASA Technical Reports Server (NTRS)
Uunila, Minttu; Zubko, Nataliya; Poutanen, Markku; Kallunki, Juha; Kallio, Ulla
2013-01-01
In 2012, Metsahovi Radio Observatory together with Finnish Geodetic Institute officially became an IVS Network Station. Eight IVS sessions were observed during the year. Two spacecraft tracking and one EVN X-band experiment were also performed. In 2012, the Metsahovi VLBI equipment was upgraded with a Digital Base Band Converter, a Mark 5B+, a FILA10G, and a FlexBuff.
Improving Detection of IV Infiltrates in Neonates
Driscoll, MD, Colleen; Langer, Melissa; Burke, Susan; El Metwally, MD, Dina
2015-01-01
Neonates and infants in the neonatal intensive care unit suffer significant morbidity when intravenous (IV) catheters infiltrate. The underreporting of adverse events through hospital voluntary reporting systems, such as ours, can complicate the monitoring of low incidence events, like IV infiltrates. Based on severe cases of IV infiltrates observed in our neonatal intensive care unit, we attempted to improve the detection of all infiltrates and reduce the incidence of Stage 4 infiltrates. We developed, and initiated the use of, an evidence-based guideline for the improved surveillance, prevention, and management of IV infiltrates, with corresponding educational interventions for faculty and staff. We instituted the use of a checklist for compliance with guidelines, and as a mechanism of surveillance. The baseline incidence rate of IV infiltrates, determined by the voluntary reporting system, was 5 per 1000 line days. Following initiation of the guidelines and checklist, the IV infiltrate rate increased to 9 per 1000 line days. In most months, the detection of IV infiltrates was improved by use of the checklist. During the post-intervention period the rate of Stage 4 infiltrates, as measured by usage of nitroglycerin ointment, was significantly reduced. In conclusion, the detection of IV infiltrates was improved following our quality improvement interventions. Further, use of an evidence-based guideline for managing infiltrates may reduce the most severe infiltrate injuries. PMID:26734388
CHLORINE ABSORPTION IN S(IV) SOLUTIONS
The report gives results of measurements of the rate of Chlorine (Cl2) absorption into aqueous sulfite/bisulfite -- S(IV) -- solutions at ambient temperature using a highly characterized stirred-cell reactor. The reactor media were 0 to 10 mM S(IV) with pHs of 3.5-8.5. Experiment...
IVS Working Group 4: VLBI Data Structures
NASA Technical Reports Server (NTRS)
Gipson, John
2010-01-01
In 2007 the IVS Directing Board established IVS Working Group 4 on VLBI Data Structures. This note discusses the current VLBI data format, goals for a new format, the history and formation of the Working Group, and a timeline for the development of a new VLBI data format.
Structural, Optical and AC Electrical Properties of Ce3+-Doped TiO2-SiO2 Matrices
NASA Astrophysics Data System (ADS)
Vidyadharan, Viji; Vasudevan, Prathibha; Karthika, S.; Joseph, Cyriac; Unnikrishnan, N. V.; Biju, P. R.
2015-08-01
We report the structural, photoluminescence and alternating current (AC) electrical properties of Ce3+-doped titanosilicate matrices prepared by nonhydrolytic sol-gel method, with different annealing temperatures. The structural characterization of the prepared samples was done by x-ray diffraction, energy dispersive spectrum and Fourier transform infrared spectroscopy measurements. The thermal stability of the prepared matrices was studied by the differential scanning calorimetric analysis. The photoluminescence spectrum shows two luminescence bands centered at 360 nm and 464 nm corresponding to the transitions 2D3/2 to 2F7/2 and 2F5/2, respectively. The dielectric responses of the samples were investigated for the frequency range 1 kHz-3 MHz at room temperature. The variation of AC conductivity, real part of dielectric constant ɛ' and imaginary part of dielectric constant ɛ″ with frequency were also studied. The Cole-Cole parameters were calculated and the semicircles observed in the plots indicate a single relaxation process which can be modelled by an equivalent parallel resistor-capacitor circuit.
ERIC Educational Resources Information Center
Hubert, Lawrence; Arabie, Phipps; Meulman, Jacqueline
1998-01-01
Introduces a method for fitting order-constrained matrices that satisfy the strongly anti-Robinson restrictions (SAR). The method permits a representation of the fitted values in a (least-squares) SAR approximating matrix as lengths of paths in a graph. The approach is illustrated with a published proximity matrix. (SLD)
Wang, Zhi-Gang; Cheng, Gong; Liu, Yan-Lin; Zhang, Ji-Lin; Sun, De-Hui; Ni, Jia-Zuan
2014-03-01
In this work, novel magnetic polymeric core-shell structured microspheres with immobilized Ce(IV), Fe3O4@SiO2@PVPA-Ce(IV), were designed rationally and synthesized successfully via a facile route for the first time. Magnetic Fe3O4@SiO2 microspheres were first prepared by directly coating a thin layer of silica onto Fe3O4 magnetic particles using a sol-gel method, a poly(vinylphosphonic acid) (PVPA) shell was then coated on the Fe3O4@SiO2 microspheres to form Fe3O4@SiO2@PVPA microspheres through a radical polymerization reaction, and finally Ce(IV) ions were robustly immobilized onto the Fe3O4@SiO2@PVPA microspheres through strong chelation between Ce(IV) ions and phosphate moieties in the PVPA. The applicability of the Fe3O4@SiO2@PVPA-Ce(IV) microspheres for selective enrichment and rapid separation of phosphopeptides from proteolytic digests of standard and real protein samples was investigated. The results demonstrated that the core-shell structured Fe3O4@SiO2@PVPA-Ce(IV) microspheres with abundant Ce(IV) affinity sites and excellent magnetic responsiveness can effectively purify phosphopeptides from complex biosamples for MS detection taking advantage of the rapid magnetic separation and the selective affinity between Ce(IV) ions and phosphate moieties of the phosphopeptides. Furthermore, they can be effectively recycled and show good reusability, and have better performance than commercial TiO2 beads and homemade Fe3O4@PMAA-Ce(IV) microspheres. Thus the Fe3O4@SiO2@PVPA-Ce(IV) microspheres can benefit greatly the mass spectrometric qualitative analysis of phosphopeptides in phosphoproteome research.
Evstatieva, Yana; Yordanova, Mariya; Chernev, Georgi; Ruseva, Yanislava; Nikolova, Dilyana
2014-07-04
Bioencapsulation of microbial cells in silica-based matrices has proved to be a good strategy to enhance the biosynthetic capabilities and viability of bioproducers. In the present study, mycelium and pellet cultures of strain Aspergillus oryzae PP were successfully immobilized in sol-gel hybrid matrices composed of tetraethylorthosilicate as an inorganic precursor, 5% (w/v) starch and 10 or 15% (w/v) polyethylene oxide, or 10% (w/v) calcium alginate as organic compounds. Biosynthetic activity of immobilized cultures was investigated by batch and fed-batch cultivation and the obtained results of 3042.04 IU cm(-3) were comparable with the enzyme activity of the free cell culture. Immobilized cultures retained their viability and biosynthetic capabilities up to the 744th h during fed-batch fermentation processes. Consequently, sol-gel encapsulation in hybrid matrices could be considered as a promising technique for immobilization of Aspergillus oryzae PP in order to increase the α-amylase production.
Evstatieva, Yana; Yordanova, Mariya; Chernev, Georgi; Ruseva, Yanislava; Nikolova, Dilyana
2014-01-01
Bioencapsulation of microbial cells in silica-based matrices has proved to be a good strategy to enhance the biosynthetic capabilities and viability of bioproducers. In the present study, mycelium and pellet cultures of strain Aspergillus oryzae PP were successfully immobilized in sol–gel hybrid matrices composed of tetraethylorthosilicate as an inorganic precursor, 5% (w/v) starch and 10 or 15% (w/v) polyethylene oxide, or 10% (w/v) calcium alginate as organic compounds. Biosynthetic activity of immobilized cultures was investigated by batch and fed-batch cultivation and the obtained results of 3042.04 IU cm−3 were comparable with the enzyme activity of the free cell culture. Immobilized cultures retained their viability and biosynthetic capabilities up to the 744th h during fed-batch fermentation processes. Consequently, sol–gel encapsulation in hybrid matrices could be considered as a promising technique for immobilization of Aspergillus oryzae PP in order to increase the α-amylase production. PMID:26740773
Rheological characterization of polysaccharide-surfactant matrices for cosmetic O/W emulsions.
Bais, D; Trevisan, A; Lapasin, R; Partal, P; Gallegos, C
2005-10-15
Rheometrical techniques can be profitably used for polysaccharide matrices in order to evaluate their suitability for the preparation of stable cosmetic O/W emulsions. In particular, the rheological properties of aqueous scleroglucan systems were investigated under continuous and oscillatory shear conditions in a polymer concentration range (0.2-1.2% w/w) embracing the sol/gel transition. The effects due to the addition of two different surfactants (up to 10% w/w) were examined at constant polymer concentration (0.4% w/w). The selected additives are a nonionic polymeric siliconic surfactant (dimethicone copolyol) and a cationic surfactant (tetradecyltrimethylammonium bromide), respectively. Polysaccharide-surfactant interactions leading to complex formation were detected also through rheology. The combined action of both nonionic and cationic surfactants in the polymer solution was examined at two different surfactant concentration levels (5 and 10% w/w), demonstrating the beneficial effects produced on the mechanical properties of the polymer matrix by the coexistence of both surfactants. Such beneficial effects are confirmed by the stability and rheology shown by the emulsions prepared. In this way, the results point out the good agreement between the rheology of the continuous phase and the final characteristics of the emulsion obtained.
Reaction diffusion model of the enzymatic erosion of insoluble fibrillar matrices.
Tzafriri, Abraham R; Bercovier, Michel; Parnas, Hanna
2002-01-01
Predicting the time course of in vivo biodegradation is a key issue in the design of an increasing number of biomedical applications such as sutures, tissue analogs and drug-delivery devices. The design of such biodegradable devices is hampered by the absence of quantitative models for the enzymatic erosion of solid protein matrices. In this work, we derive and simulate a reaction diffusion model for the enzymatic erosion of fibrillar gels that successfully reproduces the main qualitative features of this process. A key aspect of the proposed model is the incorporation of steric hindrance into the standard Michaelis-Menten scheme for enzyme kinetics. In the limit of instantaneous diffusion, the model equations are analogous to the standard equations for enzymatic degradation in solution. Invoking this analogy, the total quasi-steady-state approximation is used to derive approximate analytical solutions that are valid for a wide range of in vitro conditions. Using these analytical approximations, an experimental-theoretical method is derived to unambiguously estimate all the kinetic model parameters. Moreover, the analytical approximations correctly describe the characteristic hyperbolic dependence of the erosion rate on enzyme concentration and the zero-order erosion of thin fibers. For definiteness, the analysis of published experimental results of enzymatic degradation of fibrillar collagen is demonstrated, and the role of diffusion in these experiments is elucidated. PMID:12124264
Arthur, M J; Friedman, S L; Roll, F J; Bissell, D M
1989-01-01
We report a proteinase that degrades basement-membrane (type IV) collagen and is produced by the liver. Its cellular source is lipocytes (fat-storing or Ito cells). Lipocytes were isolated from normal rat liver and established in primary culture. The cells synthesize and secrete a neutral proteinase, which by gelatin-substrate gel electrophoresis and gel filtration chromatography, has a molecular mass of 65,000 D. The enzyme is secreted in latent form and is activated by p-aminophenylmercuric acetate but not by trypsin. Enzyme activity in the presence of EDTA is restored selectively by zinc and is unaffected by serine-protease inhibitors. In assays with radiolabeled soluble substrates, it degrades native type IV (basement membrane) collagen but not interstitial collagen types I or V and exhibits no activity against laminin or casein. At temperatures causing partial denaturation of soluble collagen in vitro, it rapidly degrades types I and V. Thus, it is both a type IV collagenase and gelatinase. The enzyme may play a role in initiating breakdown of the subendothelial matrix in the Disse space as well as augmenting the effects of collagenases that attack native interstitial collagen. Images PMID:2551922
Optical sol-gel materials based on binding and catalysis by biomolecules
Zink, J.I.; Dunn, B.; Yamanaka, S.; Lan, E.; Valentine, J.S.; Chung, K.E.
1994-12-31
The proteins copper-zinc superoxide dismutase (CuZnSOD), cytochrome c, myoglobin, hemoglobin, and bacterio-rhodopsin are encapsulated in stable, optically transparent porous, silica glass matrices prepared by the sol-gel method such that the biomolecules retain their characteristic reactivities and spectroscopic properties. The resulting glasses allow transport of small molecules into and out of the glasses at reasonable rates but retain the protein molecules within their pores. The transparency of the glasses enables the chemical reactions of the immobilized proteins to be monitored by means of changes in their visible absorption spectra. Silica glasses containing the immobilized proteins have similar reactivities and spectroscopic properties to those found for the proteins in solution. The enzymes glucose oxidase and peroxidase were also encapsulated in transparent silica glass matrices. Upon exposure to glucose solutions, a colored glass is formed that can be used as the active element in a solid state optically based glucose sensor. Likewise, gels containing oxalate oxidase and peroxidase exhibit spectroscopic changes upon exposure to aqueous solutions containing oxalic acid.
Efficient linear algebra routines for symmetric matrices stored in packed form.
Ahlrichs, Reinhart; Tsereteli, Kakha
2002-01-30
Quantum chemistry methods require various linear algebra routines for symmetric matrices, for example, diagonalization or Cholesky decomposition for positive matrices. We present a small set of these basic routines that are efficient and minimize memory requirements.
Mean Atomic Weight of Chondrules and Matrices in Semarkona, Allende and Sharps Meteorites
NASA Astrophysics Data System (ADS)
Szurgot, M.
2017-02-01
Mean atomic weight Amean of chondrules and matrices of Semarkona, Allende and Sharps meteorites was determined using chemical composition and Amean(Fe/Si) dependence. Amean values of matrices are higher than chondrules and meteorites.
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.
Nondenaturing agarose gel electrophoresis of RNA.
Rio, Donald C; Ares, Manuel; Hannon, Gregory J; Nilsen, Timothy W
2010-06-01
INTRODUCTION Perhaps the most important and certainly the most often used technique in RNA analysis is gel electrophoresis. Because RNAs are negatively charged, they migrate toward the anode in the presence of electric current. The gel acts as a sieve to selectively impede the migration of the RNA in proportion to its mass, given that its mass is generally proportional to its charge. Because mass is approximately related to chain length, the length of an RNA is more generally determined by its migration. In addition, topology (i.e., circularity) can affect migration, making RNAs appear longer on the gel than they actually are. There are two common types of gel: polyacrylamide and agarose. For most applications involving RNAs of < or =600 nucleotides, denaturing acrylamide gels are most appropriate. In contrast, agarose gels are generally used to analyze RNAs of > or =600 nucleotides, and are especially useful for analysis of mRNAs (e.g., by Northern blotting). RNA analysis on agarose gels is essentially identical to DNA analysis (except that the gel boxes used must be dedicated to RNA work or to other ribonuclease-free work). Here we describe the use of straightforward Tris borate, EDTA (TBE) gels for routine analysis. These gels are appropriate for determining the quantity and integrity of RNA before using it for other applications. This procedure should not be used to determine size with accuracy, because the RNA will not remain in its extended state throughout the run.
Molecular imprinting in sol-gel matrix.
Gupta, Radha; Kumar, Ashok
2008-01-01
Molecular imprinting is a newly developed methodology which provides molecular assemblies of desired structures and properties and is being increasingly used for several applications such as in separation processes, microreactors, immunoassays and antibody mimics, catalysis, artificial enzymes, biosensor recognition elements and bio- and chemo-sensors. The ambient processing conditions and versatility of the sol-gel process makes sol-gel glassy matrix suitable for molecular imprinting. The progress of sol-gel based molecular imprinted polymers (MIPs) for various applications can be seen from the growing number of publications. The main focus of the review is molecular imprinting in sol-gel matrix and applications of molecular imprinted sol-gel derived materials for the development of sensors. Combining sol-gel process with molecular imprinting enables to procure the sensors with greater sensitivity and selectivity necessary for sensing applications. The merits, problems, challenges and factors affecting molecular imprinting in sol-gel matrix have been discussed. Considerable attention has been drawn on recent developments like use of organically modified silane precursors (ORMOSILS) for the synthesis of hybrid molecular imprinted polymers (HMIPs) and applying surface sol-gel process for molecular imprinting. The development of molecular imprinted sol-gel nanotubes for biochemical separation and bio-imprinting is a new advancement and is under progress. Templated xerogels and molecularly imprinted sol-gel films provide a good platform for various sensor applications.
Photorefractive sol-gel materials
Chaput, F.; Boilot, J.P.; Gacoin, T.; Darracq, B.; Riehl, D.; Canva, M.; Levy, Y.; Brun, A.
1996-12-31
The authors report the synthesis and characterization of photorefractive sol-gel materials that possess covalently attached push-pull azobenzene and carbazole moieties. Molecular structural characterization of the modified silane monomers was achieved by {sup 1}H NMR and infra red spectroscopy. The second-order nonlinear optical properties of the organic-inorganic hybrid films prepared from modified silane monomers were evaluated by second-harmonic generation. The stabilized value of the second harmonic coefficient, d{sub 33}, of films poled by corona discharge, at 1,064 nm fundamental wavelength was found to be 107 pm/V. Photorefractivity was clearly displayed from a two beam coupling experiment.
Surprising Coordination Geometry Differences in Ce(IV)- and Pu(IV)-Maltol Complexes
Lawrence Berkeley National Laboratory; Raymond, Kenneth; Szigethy, Geza; Xu, Jide; Gorden, Anne E.V.; Teat, Simon J.; Shuh, David K.; Raymond, Kenneth N.
2008-02-12
As part of a study to characterize the detailed coordination behavior of Pu(IV), single crystal X-ray diffraction structures have been determined for Pu(IV) and Ce(IV) complexes with the naturally-occurring ligand maltol (3-hydroxy-2-methyl-pyran-4-one) and its derivative bromomaltol (5-bromo-3-hydroxy-2-methyl-pyran-4-one). Although Ce(IV) is generally accepted as a structural analog for Pu(IV), and the maltol complexes of these two metals are isostructural, the corresponding bromomaltol complexes are strikingly different with respect to ligand orientation about the metal ion: All complexes exhibit trigonal dodecahedral coordination geometry but the Ce(IV)-bromomaltol complex displays an uncommon ligand arrangement not mirrored in the Pu(IV) complex, although the two metal species are generally accepted to be structural analogs.
What Do Raven's Matrices Measure? An Analysis in Terms of Sex Differences
ERIC Educational Resources Information Center
Mackintosh, N. J.; Bennett, E. S.
2005-01-01
Although it is sometimes claimed that Raven's Matrices provide an almost pure measure of g, there is evidence that the easier items in the Standard Progressive Matrices and in Set I of the Advanced Matrices measure a perceptual or Gestalt factor distinct from the more analytic items in the rest of the tests. There is also, however, both factor…
Tapia, Liliana U; Lizana, Pablo A; Orellana, Yasna Z; Villagrán, Francisca S; Arias, Vanessa F; Almagià, Atilio F; Burrows, Raquel A; Ivanovic, Daniza M
2013-01-01
Objetivos: El objetivo de este estudio fue determinar la relación entre el somatotipo y la habilidad intelectual (HA) en estudiantes de 11-12 y 15-16 años de edad de la Región Metropolitana, Chile. Métodos: Se registró una muestra representativa de 1.015 escolares de acuerdo a los resultados del sistema de medición de la calidad de la educación (SIMCE) 2009. Se evaluó el somatotipo de Heath-Carter y la HA de acuerdo al Test de Matrices Progresivas de Raven. Resultados: Un 59% presentó un somatotipo endomórfico, 28% mesomórfico y 13% ectomorfo. La HA se distribuyó en: 11,2% Grado I, 26,8% Grado II, 41% Grado III, 17,6% Grado IV y 3,2% Grado V. Se presenta una correlación significativa positiva con el componente endomórfico (r = 0,074 p = 0,02), y sólo en mujeres (r = 0,109 p = 0,02), a la vez se observa una relación significativa positiva con el componente ectomorfo (r = 0,067 p < 0,05). Conclusiones: Esto sugiere que otras variables estarían influyendo más fuertemente en la HA, además de apoyar la no discriminación por biotipo en los establecimientos educacionales.
Stage IV work hardening in cubic metals
Rollett, A.D.; Kocks, U.F.; Doherty, R.D.
1986-01-01
The work hardening of fcc metals at large strains is discussed with reference to the linear stress-strain behavior often observed at large strains and known as Stage IV. The experimental evidence shows that Stage IV is a work hardening phenomenon that is found quite generally, even in pure fcc metals subjected to homogeneous deformation. A simple model for Stage IV in pure metals is presented, based on the accumulation of dislocation debris. Experiments are described for large strain torsion tests on four aluminum alloys. The level and extent of Stage IV scaled with the saturation stress that would represent the end of Stage III in the absence of a Stage IV. Reversing the torsion after large prestrains produced transient reductions in the work hardening. The strain rate sensitivity was also measured before and during the transient and found not to vary significantly. The microstructure observed at large strains in an Mg alloy suggest that Stage IV can occur in the absence of microband formation. Previous proposals for the cause of Stage IV are reviewed and found to be not supported by recent experimental data.
Tamain, Christelle; Dumas, Thomas; Hennig, Christoph; Guilbaud, Philippe
2017-03-10
Three tetravalent actinide (An(IV)) hexanuclear clusters with the octahedral core [An6(OH)4O4]12+ (An(IV) = U(IV), Np(IV), Pu(IV)) were structurally characterized in solid state and in aqueous solution using single crystal X-ray diffraction, X-ray absorption, IR, Raman and UV-Visible spectroscopy. The observed structure, [An6(OH)4O4(H2O)8(HDOTA)4].HCl/HNO3.nH2O (An = U (I), Np (II), Pu (III)), consists of a An(IV) hexanuclear pseudo-octahedral cluster stabilized by DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) ligands. The six actinide atoms are connected through alternative µ3-O2- and µ3-OH- groups. EXAFS investigations combined with UV-vis spectroscopy evidence the same local structure in moderate acidic and neutral aqueous solutions. The synthesis mechanism was partially elucidated and the main physicochemical properties (pH range stability, solubility and protonation constant) of the cluster were determined. The results underline the importance (i) to consider such polynuclear species in thermodynamic models and (ii) of competing reactions between hydrolysis and complexation. It is interesting to note that the same synthesis route with thorium(IV) leads to the formation of a dimer, Th2(H2O)10(H2DOTA)2.4NO3.xH2O (IV), which contrasts to the structure of the other An(IV) hexamers.
NASA Astrophysics Data System (ADS)
Marchesan, Melissa Andréia; Barros, Felipe; Porto, Saulo; Zaitter, Suellen; Brugnera, Aldo, Jr.; Sousa-Neto, Manoel D.
2007-02-01
This study evaluated ex vivo the influence of the number of gel/LED-laser applications/activations on cervical microleakage of two different barrier materials used for protection during whitening of endodontically treated teeth. Eighty-four canines were instrumented and obturated with epoxy resin sealer. The seal was removed 2 mm beyond the cemento-enamel junction for barrier placement and the teeth were divided into two groups of 40 teeth each: G1, zinc phosphate cement; G2, glass ionomer cement. The two groups were subdivided into 4 subgroups (n=10 each): I) no gel or LED-laser application; II) one gel application and two LED-laser activations; III) two gel applications and four LED-laser activations; IV) three gel applications and six LED-laser activations. The teeth were immersed in India ink for 7 days, decalcified and cleared. Cervical microleakage was quantified with a measurement microscope. Statistical analysis showed that zinc phosphate caused significantly lower microleakage than glass ionomer cement (presented microleakage in all subgroups). However, after two (p<0.01) and three (p<0.001) applications of gel, there was statistially significant microleakage in zinc phosphate barriers. Based on the present results, it can be concluded that cervical barriers with zinc phosphate cement show less cervical microleakage and that two or more applications/activations of gel/LED-laser significantly increase microleakage.
Active gel model of amoeboid cell motility
NASA Astrophysics Data System (ADS)
Callan-Jones, A. C.; Voituriez, R.
2013-02-01
We develop a model of amoeboid cell motility based on active gel theory. Modeling the motile apparatus of a eukaryotic cell as a confined layer of finite length of poroelastic active gel permeated by a solvent, we first show that, due to active stress and gel turnover, an initially static and homogeneous layer can undergo a contractile-type instability to a polarized moving state in which the rear is enriched in gel polymer. This agrees qualitatively with motile cells containing an actomyosin-rich uropod at their rear. We find that the gel layer settles into a steadily moving, inhomogeneous state at long times, sustained by a balance between contractility and filament turnover. In addition, our model predicts an optimal value of the gel-substrate adhesion leading to maximum layer speed, in agreement with cell motility assays. The model may be relevant to motility of cells translocating in complex, confining environments that can be mimicked experimentally by cell migration through microchannels.
Automated apparatus for producing gradient gels
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.
Automated apparatus for producing gradient gels
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.
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.
Gel trapping of dense colloids.
Laxton, Peter B; Berg, John C
2005-05-01
Phase density differences in sols, foams, or emulsions often lead to sedimentation or creaming, causing problems for materials where spatial uniformity over extended periods of time is essential. The problem may be addressed through the use of rheology modifiers in the continuous phase. Weak polymer gels have found use for this purpose in the food industry where they appear to be capable of trapping dispersoid particles in a three-dimensional matrix while displaying water-like viscosities at low shear. Attempts to predict sedimentation stability in terms of particle properties (size, shape, density difference) and gel yield stress have led to qualitative success for suspensions of large particles. The effect of particle size, however, in particular the case in which colloidal dimensions are approached, has not been investigated. The present work seeks to determine useful stability criteria for colloidal dispersions in terms of readily accessible viscoelastic descriptors. Results are reported for systems consisting of 12 microm poly(methyl methacrylate) (PMMA) spheres dispersed in aqueous gellan gum. Monovalent salt concentration is varied to control rheological properties, and sedimentation/centrifugation experiments are performed to determine dispersion stability. Necessary conditions for stability consist of a minimum yield stress together with a value of tan delta less than unity.
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.
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.
Transformation matrices between non-linear and linear differential equations
NASA Technical Reports Server (NTRS)
Sartain, R. L.
1983-01-01
In the linearization of systems of non-linear differential equations, those systems which can be exactly transformed into the second order linear differential equation Y"-AY'-BY=0 where Y, Y', and Y" are n x 1 vectors and A and B are constant n x n matrices of real numbers were considered. The 2n x 2n matrix was used to transform the above matrix equation into the first order matrix equation X' = MX. Specially the matrix M and the conditions which will diagonalize or triangularize M were studied. Transformation matrices P and P sub -1 were used to accomplish this diagonalization or triangularization to return to the solution of the second order matrix differential equation system from the first order system.
Properties of Zero-Free Transfer Function Matrices
NASA Astrophysics Data System (ADS)
D. O. Anderson, Brian; Deistler, Manfred
Transfer functions of linear, time-invariant finite-dimensional systems with more outputs than inputs, as arise in factor analysis (for example in econometrics), have, for state-variable descriptions with generic entries in the relevant matrices, no finite zeros. This paper gives a number of characterizations of such systems (and indeed square discrete-time systems with no zeros), using state-variable, impulse response, and matrix-fraction descriptions. Key properties include the ability to recover the input values at any time from a bounded interval of output values, without any knowledge of an initial state, and an ability to verify the no-zero property in terms of a property of the impulse response coefficient matrices. Results are particularized to cases where the transfer function matrix in question may or may not have a zero at infinity or a zero at zero.
Spectral density of generalized Wishart matrices and free multiplicative convolution.
Młotkowski, Wojciech; Nowak, Maciej A; Penson, Karol A; Życzkowski, Karol
2015-07-01
We investigate the level density for several ensembles of positive random matrices of a Wishart-like structure, W=XX(†), where X stands for a non-Hermitian random matrix. In particular, making use of the Cauchy transform, we study the free multiplicative powers of the Marchenko-Pastur (MP) distribution, MP(⊠s), which for an integer s yield Fuss-Catalan distributions corresponding to a product of s-independent square random matrices, X=X(1)⋯X(s). New formulas for the level densities are derived for s=3 and s=1/3. Moreover, the level density corresponding to the generalized Bures distribution, given by the free convolution of arcsine and MP distributions, is obtained. We also explain the reason of such a curious convolution. The technique proposed here allows for the derivation of the level densities for several other cases.
Spectral density of generalized Wishart matrices and free multiplicative convolution
NASA Astrophysics Data System (ADS)
Młotkowski, Wojciech; Nowak, Maciej A.; Penson, Karol A.; Życzkowski, Karol
2015-07-01
We investigate the level density for several ensembles of positive random matrices of a Wishart-like structure, W =X X† , where X stands for a non-Hermitian random matrix. In particular, making use of the Cauchy transform, we study the free multiplicative powers of the Marchenko-Pastur (MP) distribution, MP⊠s, which for an integer s yield Fuss-Catalan distributions corresponding to a product of s -independent square random matrices, X =X1⋯Xs . New formulas for the level densities are derived for s =3 and s =1 /3 . Moreover, the level density corresponding to the generalized Bures distribution, given by the free convolution of arcsine and MP distributions, is obtained. We also explain the reason of such a curious convolution. The technique proposed here allows for the derivation of the level densities for several other cases.
Chemical stability of titanium diboride reinforcement in nickel aluminide matrices
NASA Technical Reports Server (NTRS)
Rigney, J. D.; Lewandowski, J. J.
1993-01-01
Chemical stability of TiB2 reinforcement in NiAl (45 at percent Al) and Ni3Al (24 at percent Al) matrices has been theoretically and experimentally investigated. Calculations were made using thermodynamic properties of the systems to predict behavior at temperatures between 1173 and 1573 K. Experimental investigation of hot-press consolidated TiB2 particulate/prealloyed matrix powder blends were conducted using energy dispersive X-ray analysis, XRD, AES, and TEM. The theoretical and experimental analyses suggest that TiB2 is chemically stable in both matrices up to 1573 K; however, TiB2 was found to be less active in NiAl than in Ni3Al due to lower nickel activity in NiAl.
Joint Estimation of Multiple High-dimensional Precision Matrices
Cai, T. Tony; Li, Hongzhe; Liu, Weidong; Xie, Jichun
2017-01-01
Motivated by analysis of gene expression data measured in different tissues or disease states, we consider joint estimation of multiple precision matrices to effectively utilize the partially shared graphical structures of the corresponding graphs. The procedure is based on a weighted constrained ℓ∞/ℓ1 minimization, which can be effectively implemented by a second-order cone programming. Compared to separate estimation methods, the proposed joint estimation method leads to estimators converging to the true precision matrices faster. Under certain regularity conditions, the proposed procedure leads to an exact graph structure recovery with a probability tending to 1. Simulation studies show that the proposed joint estimation methods outperform other methods in graph structure recovery. The method is illustrated through an analysis of an ovarian cancer gene expression data. The results indicate that the patients with poor prognostic subtype lack some important links among the genes in the apoptosis pathway.
Optimal Estimation and Rank Detection for Sparse Spiked Covariance Matrices.
Cai, Tony; Ma, Zongming; Wu, Yihong
2015-04-01
This paper considers a sparse spiked covariancematrix model in the high-dimensional setting and studies the minimax estimation of the covariance matrix and the principal subspace as well as the minimax rank detection. The optimal rate of convergence for estimating the spiked covariance matrix under the spectral norm is established, which requires significantly different techniques from those for estimating other structured covariance matrices such as bandable or sparse covariance matrices. We also establish the minimax rate under the spectral norm for estimating the principal subspace, the primary object of interest in principal component analysis. In addition, the optimal rate for the rank detection boundary is obtained. This result also resolves the gap in a recent paper by Berthet and Rigollet [2] where the special case of rank one is considered.
Immobilization of tyrosinase in polysiloxane/polypyrrole copolymer matrices.
Arslan, Ahu; Kiralp, Senem; Toppare, Levent; Yagci, Yusuf
2005-04-01
Immobilization of tyrosinase in conducting copolymer matrices of pyrrole functionalized polydimethylsiloxane/polypyrrole (PDMS/PPy) was achieved by electrochemical polymerization. The polysiloxane/polypyrrole/tyrosinase electrode was constructed by the entrapment of enzyme in conducting matrices during electrochemical copolymerization. Maximum reaction rate (V(max)) and Michaelis-Menten constant (K(m)) were investigated for immobilized enzyme. Enzyme electrodes were prepared in two different electrolyte/solvent systems. The effect of supporting electrolytes, p-toluene sulfonic acid and sodium dodecyl sulfate on the enzyme activity and film morphology were determined. Temperature and pH optimization, operational stability and shelf-life of enzyme electrodes were also examined. Phenolic contents of green and black tea were determined by using enzyme electrodes.
NDMA formation kinetics from three pharmaceuticals in four water matrices.
Shen, Ruqiao; Andrews, Susan A
2011-11-01
N, N-nitrosodimethylamine (NDMA) is an emerging disinfection by-product (DBP) that has been widely detected in many drinking water systems and commonly associated with the chloramine disinfection process. Some amine-based pharmaceuticals have been demonstrated to form NDMA during chloramination, but studies regarding the reaction kinetics are largely lacking. This study investigates the NDMA formation kinetics from ranitidine, chlorphenamine, and doxylamine under practical chloramine disinfection conditions. The formation profile was monitored in both lab-grade water and real water matrices, and a statistical model is proposed to describe and predict the NDMA formation from selected pharmaceuticals in various water matrices. The results indicate the significant impact of water matrix components and reaction time on the NDMA formation from selected pharmaceuticals, and provide fresh insights on the estimation of ultimate NDMA formation potential from pharmaceutical precursors.
Vashaghian, Mahshid; Zandieh-Doulabi, Behrouz; Roovers, Jan-Paul; Smit, Theodoor Henri
2016-12-01
Electrospun matrices are proposed as an alternative for polypropylene meshes in reconstructive pelvic surgery. Here, we investigated the effect of fiber diameter on (1) the mechanical properties of electrospun poly (lactic-co-glycolic acid)-blended-poly(caprolactone) (PLGA/PCL) matrices; (2) cellular infiltration; and (3) the newly formed extracellular matrix (ECM) in vitro. We compared electrospun matrices with 1- and 8 μm fiber diameter and used nonporous PLGA/PCL films as controls. The 8-μm matrices were almost twice as stiff as the 1-μm matrices with 1.38 and 0.66 MPa, respectively. Matrices had the same ultimate tensile strength, but with 80% the 1-μm matrices were much more ductile than the 8-μm ones (18%). Cells infiltrated deeper into the matrices with larger pores, but cellular activity was comparable on both substrates. New ECM was deposited faster on the electrospun samples, but after 2 and 4 weeks the amount of collagen was comparable with that on nonporous films. The ECM deposited on the 1-μm matrices, and the nonporous film was about three times stiffer than the ECM found on the 8-μm matrices. Cell behavior in terms of myofibroblastic differentiation and remodeling was similar on the 1-μm matrices and nonporous films, in comparison to that on the 8-μm matrices. We conclude that electrospinning enhances the integration of host cells as compared with a nonporous film of the same material. The 1-μm matrices result in better mechanical behavior and qualitatively better matrix production than the 8-μm matrices, but with limited cellular infiltration. These data are useful for designing electrospun matrices for the pelvic floor.
Higher order matrix differential equations with singular coefficient matrices
Fragkoulis, V. C.; Kougioumtzoglou, I. A.; Pantelous, A. A.; Pirrotta, A.
2015-03-10
In this article, the class of higher order linear matrix differential equations with constant coefficient matrices and stochastic process terms is studied. The coefficient of the highest order is considered to be singular; thus, rendering the response determination of such systems in a straightforward manner a difficult task. In this regard, the notion of the generalized inverse of a singular matrix is used for determining response statistics. Further, an application relevant to engineering dynamics problems is included.
Development of biodegradable aluminium carboxymethylcellulose matrices for mosquito larvicides.
Mathew, Nisha; Kalyanasundaram, Muthuswami
2004-07-01
The use of ecofriendly biodegradable controlled-release formulations of mosquito larvicides could reduce the frequency of application and losses due to degradation of the insecticide compared with conventional formulations. Among the 20 matrices developed by entrapping the organophosphorus mosquito larvicide, fenthion, in carboxymethylcellulose ionotropically cross-linked with aluminium ions which were studied for release profiles, two matrices, CRF3b and CRF5b, were found to be stable for 16 and 14 weeks under simulated field conditions. The average concentration of fenthion released per week ranged from 0.06 to 3.5 mg litre(-1) for CRF3b and 0.09 to 2.72 mg litre(-1) for CRF5b. Of these two formulations, CRF3b was the more stable, maintaining the concentration of the active ingredient at the level required to effect mosquito control. The cumulative release of fenthion per pellet was 80% from CRF3b and 72% from CRF5b. Based on the study with fenthion, two similar matrices for triflumuron, a benzoylphenylurea insect growth regulator, STAR3b and STAR5b were developed. These matrices were stable up to 16 weeks with the average concentration of triflumuron released per week ranging from 0.05 to 3.44 mg litre(-1) for STAR3b and 0.07 to 2.71 mg litre(-1) for STARSb. The cumulative release of triflumuron per pellet was 75% from STAR3b and 76% from STAR5b. From the results of this study under simulated conditions, it is estimated that the application of four pellets of either fenthion or triflumuron per square metre of the breeding surface may play a useful role in controlling Culex quinquefasciatus Say in larval habitats for about 4 months.
Implications of 4 texture zeros mass matrices for neutrino anomalies
NASA Astrophysics Data System (ADS)
Gill, P. S.; Gupta, Manmohan
1998-04-01
Phenomenological 4 texture zeros mass matrices, successful in accommodating the CKM phenomenology, are used to simultaneously explain the three neutrino anomalies: the solar neutrino problem (SNP), the atmospheric neutrino problem (ANP), and the LSND anomaly. When the SNP is resolved through vacuum oscillations, we obtain a solution implying large mixing. In case the SNP is resolved through the MSW mechanism, the neutrino masses follow a ``natural'' hierarchy.
Solution of the determinantal assignment problem using the Grassmann matrices
NASA Astrophysics Data System (ADS)
Karcanias, Nicos; Leventides, John
2016-02-01
The paper provides a direct solution to the determinantal assignment problem (DAP) which unifies all frequency assignment problems of the linear control theory. The current approach is based on the solvability of the exterior equation ? where ? is an n -dimensional vector space over ? which is an integral part of the solution of DAP. New criteria for existence of solution and their computation based on the properties of structured matrices are referred to as Grassmann matrices. The solvability of this exterior equation is referred to as decomposability of ?, and it is in turn characterised by the set of quadratic Plücker relations (QPRs) describing the Grassmann variety of the corresponding projective space. Alternative new tests for decomposability of the multi-vector ? are given in terms of the rank properties of the Grassmann matrix, ? of the vector ?, which is constructed by the coordinates of ?. It is shown that the exterior equation is solvable (? is decomposable), if and only if ? where ?; the solution space for a decomposable ?, is the space ?. This provides an alternative linear algebra characterisation of the decomposability problem and of the Grassmann variety to that defined by the QPRs. Further properties of the Grassmann matrices are explored by defining the Hodge-Grassmann matrix as the dual of the Grassmann matrix. The connections of the Hodge-Grassmann matrix to the solution of exterior equations are examined, and an alternative new characterisation of decomposability is given in terms of the dimension of its image space. The framework based on the Grassmann matrices provides the means for the development of a new computational method for the solutions of the exact DAP (when such solutions exist), as well as computing approximate solutions, when exact solutions do not exist.
Supercritical Fluid Infusion of Iron Additives in Polymeric Matrices
NASA Technical Reports Server (NTRS)
Nazem, Negin; Taylor, Larry T.
1999-01-01
The objective of this project was the experimentation to measure preparation of iron nanophases within polymeric matrices via supercritical fluid infusion of iron precursors followed by thermal reduction. Another objective was to determine if supercritical CO2 could infuse into the polymer. The experiment is described along with the materials, and the supercritical fluid infusion and cure procedures. X-ray photoelectron spectra and transmission electron micrographs were obtained. The results are summarized in charts, and tables.
Spectrum of Lebesgue Measure Zero for Jacobi Matrices of Quasicrystals
NASA Astrophysics Data System (ADS)
Beckus, Siegfried; Pogorzelski, Felix
2013-09-01
We study one-dimensional random Jacobi operators corresponding to strictly ergodic dynamical systems. We characterize the spectrum of these operators via non-uniformity of the transfer matrices and vanishing of the Lyapunov exponent. For aperiodic, minimal subshifts satisfying the so-called Boshernitzan condition this gives that the spectrum is supported on a Cantor set with Lebesgue measure zero. This generalizes earlier results for Schrödinger operators.
Generating Matrices of C-nomial Coefficients and Their Spectra
2010-04-20
International Conf. Fibonacci Numbers & Applic . 2010. 14. ABSTRACT In this paper, we consider a generalization of binomial coe cients, called C{ nomial coe...combinatorial matrices, Congressus Numerantium Vol. 201 (2010), Proc. Internat. Conf. Fibonacci Numbers & Applic . – ’08, 223–236. [18] E. Kilic and P...coefficients via generating func- tion, Discrete Appl. Math. 155 (2007), 2017–2024. [24] S. Vajda, Fibonacci & Lucas numbers , and the golden section, John
Factoring symmetric indefinite matrices on high-performance architectures
NASA Technical Reports Server (NTRS)
Jones, Mark T.; Patrick, Merrell L.
1990-01-01
The Bunch-Kaufman algorithm is the method of choice for factoring symmetric indefinite matrices in many applications. However, the Bunch-Kaufman algorithm does not take advantage of high-performance architectures such as the Cray Y-MP. Three new algorithms, based on Bunch-Kaufman factorization, that take advantage of such architectures are described. Results from an implementation of the third algorithm are presented.
Power series evaluation of transition and covariance matrices.
NASA Technical Reports Server (NTRS)
Bierman, G. J.
1972-01-01
Reexamination power series solutions to the matrix covariance differential equation and the transition differential equation. Truncation error bounds are derived which are computationally attractive and which extend previous results. Polynomial approximations are obtained by exploiting the functional equations satisfied by the transition and covariance matrices. The series-functional equation propagation technique represents a fast and accurate alternative to the numerical integration of the time-invariant transition and covariance equations.
Spectral properties of sums of Hermitian matrices and algebraic geometry
NASA Astrophysics Data System (ADS)
Chau Huu-Tai, P.; Van Isacker, P.
2016-04-01
It is shown that all the eigenvectors of a sum of Hermitian matrices belong to the same algebraic variety. A polynomial system characterizing this variety is given and a set of nonlinear equations is derived which allows the construction of the variety. Moreover, in some specific cases, explicit expressions for the eigenvectors and eigenvalues can be obtained. Explicit solutions of selected models are also derived.
Dissolution Rate of Propellant Energetics from Nitrocellulose Matrices
2012-09-01
Engineer Research and Development Center 72 Lyme Road Hanover, NH 03755 Katerina Dontsova Biosphere 2 Earthscience, University of Arizona 845 N...ER D C/ CR R EL T R -1 2 -9 ER-1691 Dissolution Rate of Propellant Energetics from Nitrocellulose Matrices C ol d R eg io n s R es ea...transformation rates measured. As a result, no 2 ,-4-DNT was detected in column outflow. NG experienced both adsorption and transformation in the soils
Partitioning Rectangular and Structurally Nonsymmetric Sparse Matrices for Parallel Processing
B. Hendrickson; T.G. Kolda
1998-09-01
A common operation in scientific computing is the multiplication of a sparse, rectangular or structurally nonsymmetric matrix and a vector. In many applications the matrix- transpose-vector product is also required. This paper addresses the efficient parallelization of these operations. We show that the problem can be expressed in terms of partitioning bipartite graphs. We then introduce several algorithms for this partitioning problem and compare their performance on a set of test matrices.
On the Assessment of Psychometric Adequacy in Correlation Matrices.
ERIC Educational Resources Information Center
Dziuban, Charles D.; Shirkey, Edwin C.
Three techniques for assessing the adequacy of correlation matrices for factor analysis were applied to four examples from the literature. The methods compared were: (1) inspection of the off diagonal elements of the anti-image covariance matrix S(to the 2nd) R(to the -1) and S(to the 2nd); (2) the Measure of Sampling Adequacy (M.S.A.), and (3)…
Ideal amino acid exchange forms for approximating substitution matrices.
Pokarowski, Piotr; Kloczkowski, Andrzej; Nowakowski, Szymon; Pokarowska, Maria; Jernigan, Robert L; Kolinski, Andrzej
2007-11-01
We have analyzed 29 published substitution matrices (SMs) and five statistical protein contact potentials (CPs) for comparison. We find that popular, 'classical' SMs obtained mainly from sequence alignments of globular proteins are mostly correlated by at least a value of 0.9. The BLOSUM62 is the central element of this group. A second group includes SMs derived from alignments of remote homologs or transmembrane proteins. These matrices correlate better with classical SMs (0.8) than among themselves (0.7). A third group consists of intermediate links between SMs and CPs - matrices and potentials that exhibit mutual correlations of at least 0.8. Next, we show that SMs can be approximated with a correlation of 0.9 by expressions c(0) + x(i)x(j) + y(i)y(j) + z(i)z(j), 1
Shuttle Program. Euler angles, quaternions, and transformation matrices working relationships
NASA Technical Reports Server (NTRS)
Henderson, D. M.
1977-01-01
A brief mathematical development of the relationship between the Euler angles and the transformation matrix, the quaternion and the transformation matrix, and the Euler angles and the quaternion is presented. The analysis and equations presented apply directly to current space shuttle problems. The twelve three-axis Euler transformation matrices are given as functions of the Euler angles, the equations for the quaternion as a funtion of the Euler angles, and the Euler angles as a function of the transformation matrix elements.
Liu, Wei; Zhang, Lan; Chen, Shengping; Duan, Hongbin; Chen, Xi; Wei, Zhenyi; Chen, Guonan
2009-01-05
A kind of homemade solid-phase microextraction fibre coupled with gas chromatography-mass spectrometry (GC-MS) was developed for trace analysis of antiestrogens (tamoxifen, cis- and trans-clomiphene) in biological matrices. In this method, derivatization was unnecessary and sample solution could be injected directly after very simple deproteinization operation. The conditions of influencing adsorption of the solid-phase microextraction (SPME) fibre and desorption of the analytes were investigated in details. Matrix effects were studied in different background. Under optimum conditions, the proposed method was further validated by spiking analytes into rabbit liver solutions. Linear ranges of tamoxifen, cis- and trans-clomiphene were 0.02-2.56, 0.08-2.56 and 0.16-2.56 ng mL(-1), respectively. The limits of quantitation were in the range of 0.02-0.16 ng mL(-1). The intra-day accuracy was ranged 96.2-106.2% and precision were in the range of 5.1-8.7%. The extraction recoveries of the antiestrogens in rabbit liver solution were between 73.8% and 113.1%, and R.S.D.s were from 3.6% to 14.1%. The results show that the homemade sol-gel coating is suitable for determination of trace antiestrogens in complex matrices. The proposed approach was proved to be rapid, simple, easy, sensitive and reproducible for trace analysis of antiestrogens in biological matrices.
Food gels: gelling process and new applications.
Banerjee, Soumya; Bhattacharya, Suvendu
2012-01-01
Food gels are viscoelastic substances and several gelled products are manufactured throughout the world. The gelling agents in foods are usually polysaccharides and proteins. In food gels, the polymer molecules are not cross-linked by covalent bonds with the exception of disulphide bonds in some protein gels. Instead, the molecules are held together by a combination of weak inter-molecular forces like hydrogen bonds, electrostatic forces, Van der Waals forces, and hydrophobic interactions. Polysaccharides including hydrocolloids are strongly hydrated in aqueous medium but they tend to have less ordered structures. The mechanism of gelation depends on the nature of the gelling agent(s) and on the conditions of gel formation like the temperature, the presence of ions, the pH, and the concentration of gelling agents, etc. Characterization of gels can be performed in several ways of which rheological measurements are frequently practiced. Multi-component or mixed gel system is an important area of interest in which two or more gelling components are simultaneously used to achieve certain specific structural and functional characteristics. We here discuss about the different gels and gelling agents, the characterization of gels, and the mechanism of gelation with an emphasis on mixed or multi-component gels that would have significant commercial applications.
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.
Conducting polymer electrodes for gel electrophoresis.
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.
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.
Dispersion of Mixed Brush Gold Nanorods in Polymer Matrices
NASA Astrophysics Data System (ADS)
Ferrier, Robert; Koski, Jason; Riggleman, Robert; Composto, Russell
In this work we investigate, both experimentally and through hybrid particle/self-consistent field theoretic (hSCFT) calculations, the dispersion state of gold nanorods (AuNRs) grafted with homopolymer, bidispersed, or mixed polymer brushes. AuNRs are grafted with 11.5 kg/mol PS (HNRs), 11.5 kg/mol PS and 5.3 kg/mol PS (BNRs), or 11.5 kg/mol PS and 5 kg/mol poly(methyl methacrylate) (PMMA) (MBNRs) and cast in PS or PMMA films consisting of short to very long chains compared to the grafted brush. We further investigated the MBNR systems by varying the length of the PS brush. Overall, we find that the MBNRs dispersed markedly better than the other brush types (HNRs or BNRs) in PS matrices. We utilize hSCFT calculations, in particular potential of mean force (PMF) and brush profile calculations, to elucidate the thermodynamics of these systems. The PMFs and brush profiles exhibit similar trends for the BNRs and MBNRs where the short grafted chain forces the longer grafted chain away from the AuNR surface and promotes wetting by the matrix chains. The hSCFT calculations demonstrated qualitative trends consistent with the aggregation observed for AuNRs in PMMA matrices. Therefore, we have demonstrated that MBNR dispersion in polymer matrices is enhanced compared to the HNR and BNR cases, which extends the dispersion window for new combinations of nanorods and polymers.
Asymmetric Matrices in an Analysis of Financial Correlations
NASA Astrophysics Data System (ADS)
Kwapien, J.; Drozdz, S.; Gorski, A. Z.; Oswiecimka, P.
2006-11-01
Financial markets are highly correlated systems that reveal both the inter-market dependencies and the correlations among their different components. Standard analyzing techniques include correlation coefficients for pairs of signals and correlation matrices for rich multivariate data. In the latter case one constructs a real symmetric matrix with real non-negative eigenvalues describing the correlation structure of the data. However, if one performs a correlation-function-like analysis of multivariate data, when a stress is put on investigation of delayed dependencies among different types of signals, one can calculate an asymmetric correlation matrix with complex eigenspectrum. From the Random Matrix Theory point of view this kind of matrices is closely related to Ginibre Orthogonal Ensemble (GinOE). We present an example of practical application of such matrices in correlation analyses of empirical data. By introducing the time lag, we are able to identify temporal structure of the inter-market correlations. Our results show that the American and German stock markets evolve almost simultaneously without a significant time lag so that it is hard to find imprints of information transfer between these markets. There is only an extremely subtle indication that the German market advances the American one by a few seconds.
VX fate on common matrices: evaporation versus degradation.
Columbus, Ishay; Waysbort, Daniel; Marcovitch, Itzhak; Yehezkel, Lea; Mizrahi, Dana M
2012-04-03
A study of the volatilization rate of the nerve agent VX (O-ethyl S-2-(N,N-diisopropylamino)ethyl methylphosphonothiolate) from various urban matrices in a specially designed climatic chamber (model system) is described. The performance of the model system combined with the analytical procedure produced profiles of vapor concentration obtained from samples of VX dispersed as small droplets on the surfaces of the matrices. The results indicated that the bitumen-containing surfaces such as asphalt blocks and bitumen sheets conserve VX and slow-release part of it over a long period of time. No complete mass balance could be obtained for these surfaces. Influence of environmental and experimental parameters as well as the efficacy of decontamination procedure were also measured. From smooth surface tiles a fast release of VX was measured and almost a complete mass balance was obtained, which characterizes the behavior of inert surfaces. Experiments carried out on concrete blocks showed fast decay of the concentration profile along with a very poor reconstruction of the initial quantity of VX, implying that this matrix degraded VX actively due to its multiple basic catalytic sites. To complement this study, solid-state NMR measurements were compared to add data concerning agent-fate within the matrices.
Bone generation on PHBV matrices: an in vitro study.
Köse, G Torun; Korkusuz, F; Korkusuz, P; Purali, N; Ozkul, A; Hasirci, V
2003-12-01
Bone formation was investigated in vitro by culturing rat marrow stromal osteoblasts in biodegradable, macroporous poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) (PHBV) matrices over a period of 60 days. Foams were prepared after solvent evaporation and solute leaching. PHBV solutions with different concentrations were prepared in chloroform: dichloromethane (1:2, v/v). In order to create a matrix with high porosity and uniform pore sizes, sieved sucrose crystals (300-500 microm) were used. PHBV foams were treated with rf-oxygen plasma (100 W 10 min) to modify their surface chemistry and hydrophilicity with the aim of increasing the reattachment of osteoblasts. Osteoblasts were isolated from rat bone marrow and seeded onto PHBV foams. The cell density on and in the foams was determined with MTS assay. MTS results showed that osteoblasts proliferated on PHBV. Twenty-one days after seeding of incubation, growth of osteoblasts on matrices and initiation of mineralization were observed by confocal laser scanning microscopy. Increasing ALP and osteocalcin secretion during 60 days confirmed the osteoblastic phenotype of the derived stromal cells. SEM, histological evaluations and confocal laser scanning microscopy showed that osteoblasts could grow inside the matrices and lead to mineralization. Cells exhibited spindle-like morphology and had a diameter of 10-30 microm. Based on these, it could confidently be stated that PHBV seems to be a promising polymeric matrix material for bone tissue engineering.
Reproducible quantitative proteotype data matrices for systems biology
Röst, Hannes L.; Malmström, Lars; Aebersold, Ruedi
2015-01-01
Historically, many mass spectrometry–based proteomic studies have aimed at compiling an inventory of protein compounds present in a biological sample, with the long-term objective of creating a proteome map of a species. However, to answer fundamental questions about the behavior of biological systems at the protein level, accurate and unbiased quantitative data are required in addition to a list of all protein components. Fueled by advances in mass spectrometry, the proteomics field has thus recently shifted focus toward the reproducible quantification of proteins across a large number of biological samples. This provides the foundation to move away from pure enumeration of identified proteins toward quantitative matrices of many proteins measured across multiple samples. It is argued here that data matrices consisting of highly reproducible, quantitative, and unbiased proteomic measurements across a high number of conditions, referred to here as quantitative proteotype maps, will become the fundamental currency in the field and provide the starting point for downstream biological analysis. Such proteotype data matrices, for example, are generated by the measurement of large patient cohorts, time series, or multiple experimental perturbations. They are expected to have a large effect on systems biology and personalized medicine approaches that investigate the dynamic behavior of biological systems across multiple perturbations, time points, and individuals. PMID:26543201
Visualization of newt aragonitic otoconial matrices using transmission electron microscopy
NASA Technical Reports Server (NTRS)
Steyger, P. S.; Wiederhold, M. L.
1995-01-01
Otoconia are calcified protein matrices within the gravity-sensing organs of the vertebrate vestibular system. These protein matrices are thought to originate from the supporting or hair cells in the macula during development. Previous studies of mammalian calcitic, barrel-shaped otoconia revealed an organized protein matrix consisting of a thin peripheral layer, a well-defined organic core and a flocculent matrix inbetween. No studies have reported the microscopic organization of the aragonitic otoconial matrix, despite its protein characterization. Pote et al. (1993b) used densitometric methods and inferred that prismatic (aragonitic) otoconia have a peripheral protein distribution, compared to that described for the barrel-shaped, calcitic otoconia of birds, mammals, and the amphibian utricle. By using tannic acid as a negative stain, we observed three kinds of organic matrices in preparations of fixed, decalcified saccular otoconia from the adult newt: (1) fusiform shapes with a homogenous electron-dense matrix; (2) singular and multiple strands of matrix; and (3) more significantly, prismatic shapes outlined by a peripheral organic matrix. These prismatic shapes remain following removal of the gelatinous matrix, revealing an internal array of organic matter. We conclude that prismatic otoconia have a largely peripheral otoconial matrix, as inferred by densitometry.
Spectral domain of large nonsymmetric correlated Wishart matrices.
Vinayak; Benet, Luis
2014-10-01
We study complex eigenvalues of the Wishart model for nonsymmetric correlation matrices. The model is defined for two statistically equivalent but different Gaussian real matrices, as C=AB(t)/T, where B(t) is the transpose of B and both matrices A and B are of dimensions N×T. If A and B are uncorrelated, or equivalently if C vanishes on average, it is known that at large matrix dimension the domain of the eigenvalues of C is a circle centered-at-origin and the eigenvalue density depends only on the radial distances. We consider actual correlation in A and B and derive a result for the contour describing the domain of the bulk of the eigenvalues of C in the limit of large N and T where the ratio N/T is finite. In particular, we show that the eigenvalue domain is sensitive to the correlations. For example, when C is diagonal on average with the same element c≠0, the contour is no longer a circle centered at origin but a shifted ellipse. In this case we explicitly derive a result for the spectral density which again depends only on the radial distances. For more general cases, we show that the contour depends on the symmetric and antisymmetric parts of the correlation matrix resulting from the ensemble-averaged C. If the correlation matrix is normal, then the contour depends only on its spectrum. We also provide numerics to justify our analytics.
Investigation of Polycaprolactone Matrices for Intravaginal Delivery of Doxycycline.
Pathak, Meenakshi; Coombes, Allan G A; Turner, Mark S; Palmer, Cheryn; Wang, Dongjie; Steadman, Kathryn J
2015-12-01
Polycaprolactone (PCL) matrices loaded with doxycycline were produced by rapidly cooling suspensions of the drug powder in PCL solution in acetone. Drug loadings of 5%, 10%, and 15% (w/w) of the PCL content were achieved. Exposure of doxycycline powder to matrix processing conditions in the absence of PCL revealed an endothermic peak at 65°C with the main peak at 167°C, suggesting solvatomorph formation. Rapid "burst release" of 24%-32% was measured within 24 h when matrices were immersed in simulated vaginal fluid (SVF) at 37°C, because of the presence of drug at or close to the matrix surface, which is further confirmed by scanning electron microscopy. Gradual release of 66%-76% of the drug content occurred over the following 14 days. SVF containing doxycycline released from drug-loaded PCL matrices retained 81%-90% antimicrobial activity compared with the nonformulated drug. The concentrations of doxycycline predicted to be released into vaginal fluid from a PCL matrix in the form of an intravaginal ring would be sufficient to kill Neisseria gonorrhoea and many other pathogens. These results indicate that PCL may be a suitable polymer for controlled intravaginal delivery of doxycycline for the treatment of sexually transmitted infections.
Threshold partitioning of sparse matrices and applications to Markov chains
Choi, Hwajeong; Szyld, D.B.
1996-12-31
It is well known that the order of the variables and equations of a large, sparse linear system influences the performance of classical iterative methods. In particular if, after a symmetric permutation, the blocks in the diagonal have more nonzeros, classical block methods have a faster asymptotic rate of convergence. In this paper, different ordering and partitioning algorithms for sparse matrices are presented. They are modifications of PABLO. In the new algorithms, in addition to the location of the nonzeros, the values of the entries are taken into account. The matrix resulting after the symmetric permutation has dense blocks along the diagonal, and small entries in the off-diagonal blocks. Parameters can be easily adjusted to obtain, for example, denser blocks, or blocks with elements of larger magnitude. In particular, when the matrices represent Markov chains, the permuted matrices are well suited for block iterative methods that find the corresponding probability distribution. Applications to three types of methods are explored: (1) Classical block methods, such as Block Gauss Seidel. (2) Preconditioned GMRES, where a block diagonal preconditioner is used. (3) Iterative aggregation method (also called aggregation/disaggregation) where the partition obtained from the ordering algorithm with certain parameters is used as an aggregation scheme. In all three cases, experiments are presented which illustrate the performance of the methods with the new orderings. The complexity of the new algorithms is linear in the number of nonzeros and the order of the matrix, and thus adding little computational effort to the overall solution.
Spectral domain of large nonsymmetric correlated Wishart matrices
NASA Astrophysics Data System (ADS)
Vinayak, Benet, Luis
2014-10-01
We study complex eigenvalues of the Wishart model for nonsymmetric correlation matrices. The model is defined for two statistically equivalent but different Gaussian real matrices, as C =ABt/T, where Bt is the transpose of B and both matrices A and B are of dimensions N ×T. If A and B are uncorrelated, or equivalently if C vanishes on average, it is known that at large matrix dimension the domain of the eigenvalues of C is a circle centered-at-origin and the eigenvalue density depends only on the radial distances. We consider actual correlation in A and B and derive a result for the contour describing the domain of the bulk of the eigenvalues of C in the limit of large N and T where the ratio N /T is finite. In particular, we show that the eigenvalue domain is sensitive to the correlations. For example, when C is diagonal on average with the same element c ≠0, the contour is no longer a circle centered at origin but a shifted ellipse. In this case we explicitly derive a result for the spectral density which again depends only on the radial distances. For more general cases, we show that the contour depends on the symmetric and antisymmetric parts of the correlation matrix resulting from the ensemble-averaged C. If the correlation matrix is normal, then the contour depends only on its spectrum. We also provide numerics to justify our analytics.
Some thoughts on positive definiteness in the consideration of nuclear data covariance matrices
Geraldo, L.P.; Smith, D.L.
1988-01-01
Some basic mathematical features of covariance matrices are reviewed, particularly as they relate to the property of positive difiniteness. Physical implications of positive definiteness are also discussed. Consideration is given to an examination of the origins of non-positive definite matrices, to procedures which encourage the generation of positive definite matrices and to the testing of covariance matrices for positive definiteness. Attention is also given to certain problems associated with the construction of covariance matrices using information which is obtained from evaluated data files recorded in the ENDF format. Examples are provided to illustrate key points pertaining to each of the topic areas covered.
Characterization of Nanostructured n-ZnO/p-Si Heterojunction Prepared by a Simple Sol-Gel Method
NASA Astrophysics Data System (ADS)
He, Bo; Xu, Jing; Ning, Huanpo; Xiong, Hao; Xing, Huaizhong; Qin, Yuming
2016-03-01
The nanostructured ZnO film was prepared on a texturized Si wafer by a simple sol-gel method to fabricate n-ZnO/p-Si heterojunction photoelectric device. The novel sol-gel method is cheap and convenient. The structural, optical and electrical properties of the nanostructured ZnO film were studied by XRD, SEM, XPS, PL, UV-Vis spectrophotometer and Hall effect measurement. The current-voltage (I-V) curve of nanostructured ZnO/p-Si heterojunction device shows good rectifying behavior. Good photoelectric behavior is obtained.
Coreño, Juan; Martínez, Antonia; Coreño, Oscar; Bolarín, Ana; Sánchez, Félix
2003-01-01
Titania powders have been prepared by the sol-gel route from Ti (IV) ethoxide under acidic conditions. Adsorption experiments of calcium and phosphate ions on gel-derived titania suspensions were performed to suggest a likely initial step of apatite growth on its surface. Experiments were performed as a function of time and pH at 37 degrees C with and without NaCl present in the suspensions. Also, zeta (zeta) potential experiments were performed to determine the kind of calcium adsorption. Results suggest that, apparently, calcium and phosphate adsorption can act as two different initial steps for apatite growth.
Teeranachaideekul, Veerawat; Souto, Eliana B; Müller, Rainer H; Junyaprasert, Varaporn B
2008-03-01
The aim of this study was to characterize the physicochemical properties and to study in vitro release of ascorbyl palmitate from semi-solid lipid nanoparticles based on nanostructured lipid carriers (NLC gels) systems with the desired viscosity for dermal delivery. NLC gels were obtained by a one-step production procedure employing a high pressure homogenization technique using different solid lipid matrices. Ascorbyl palmitate (AP) was selected as a lipophilic active ingredient due to its range of cosmetic applications. After the production, particles within the size range 170-250 nm having polydispersity index lower than 0.3 were obtained from all formulations. After the AP incorporation into the NLC gels, the zeta potential increased to values higher than |30 mV|. Almost 100% encapsulation efficiency was observed. The obtained SEM and AFM data revealed non-spherical shaped nanoparticles. From DSC and X-ray diffraction studies, it was shown that the lipid recrystallized in the solid state possessing a less ordered structure as compared to the bulk material. The release study of active-loaded NLC gel formulations using Franz diffusion cells revealed that the type of lipid matrix affects both the rate and the release pattern. The viscoelastic measurements revealed a more elastic than viscous behaviour of NLC formulations indicating a typical gel-like structure.